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Sample records for renal plasma flow

  1. Individual renal plasma flow determination in 2 minutes

    International Nuclear Information System (INIS)

    Schlegel, J.U.; Hamway, S.A.

    1976-01-01

    A method is described for determining effective renal plasma flow, using the renal counts 1 to 2 minutes after injection and applying background subtraction as a ratio to the total amount of radioactivity injected intravenously with appropriate correction for kidney depth. It appears that this simple approach for determination of effective renal plasma flow within a matter of 2 minutes is accurate and reliable, and should be useful for a number of applications when it is important to determine total and individual renal plasma flow. The approach is recommended as a screening procedure in lieu of the determination of blood urea nitrogen and serum creatinine, with the additional advantages of gross morphology and determination of individual renal plasma flow in an absolute as well as relative manner

  2. A simple estimation of the renal plasma flow

    International Nuclear Information System (INIS)

    Shinpo, Takako

    1987-01-01

    The renal plasma flow was determined conventionally by the excretive ratio to urine using a 131 I-Hippuran renogram. In this report, we proposed the renal clearance, the product of the disappearance rate coefficient and the maximum counts of the bladder, for the simple quantitative value of renal plasma flow. The disappearance rate coefficient was calculated by approximating the exponential function of the initial slope from the disappearance curve of the heart. The renal clearances was compared with the renal plasma flow calculated by the conventional method. The results gave a high correlation coefficient of r = 0.91. The renal clearances can be calculated easily and it offers useful renogram information. (author)

  3. Measurement of effective renal plasma flow in congestive heart failure

    International Nuclear Information System (INIS)

    Tauxe, W.N.; Dubovsky, E.V.; Mantle, J.A.; Dustan, H.P.; Logic, J.R.

    1981-01-01

    In the management of patients with congestive heart failure (CHF), it is often desirable to have precise knowledge of overall renal function, including the effective renal plasma flow (ERPF). It has long been recognized that ERPF is diminished in CHF. Since glomerular filtration rate is often decreased to a much lesser extent, other noninvasive procedures such as the measurement of creatinine clearances may not be entirely suitable. ERPF determination by the single plasma sampling (SPS) method affords a rapid, simple, noninvasive, and economical technique that is quite accurate and reproducible. A SPS method has been well-tested in patients following renal transplantation plus a wide variety of nephrological disorders. We have been concerned whether the SPS method would be valid in volume expanded patients. In 28 determinations of ERPF in patients with CHF, and in five patients who did not have CHF, we have found the SPS estimation of ERPF to yield results that are not clinically significantly different from those obtained by the detailed compartmental analysis method. The volumes of 131 I-orthoiodohippurate (OIH) distribution were found to be somewhat higher in CHF than in controls, but fractional rate constants were proportionately lower so that intercompartmental flow rates and OIH concentrations were not different from controls. Therefore, the SPS estimation of ERPF is valid in patients with CHF and may be useful in monitoring the renal effects of various hemodynamic and pharmacological interventions. (orig.)

  4. Effect of PTA on blood pressure, renal plasma flow and renal venous renin activity in renovascular hypertension

    International Nuclear Information System (INIS)

    Arlart, I.P.; Dewitz, H. von; Rosenthal, J.

    1983-01-01

    Percutaneous transluminal angioplasty (PTA) is more and more accepted for interventional management of renal artery stenosis in hypertensive patients. This study was carried out to assess the behaviour of arterial blood-pressure, renal plasma flow and renal venous rening activity in renovascular hypertension following catheter dilatation. Using the data the possibility is calculated to predict the effect of PTA on blood pressure preinterventionally. The results demonstrate that a successful employment of PTA depends on a normal contralateral renal plasma flow and a normalization of plasma flow of the poststenotic kidney. Determination of plasma renin activity is only of restricted value. (orig.)

  5. Compartment model for the measurement of the effective renal plasma flow by radionuclidenephrography

    International Nuclear Information System (INIS)

    Ryabov, S.I.; Degtyareva, O.A.

    1988-01-01

    By reason of model ideas on hippuran kinetics radionuclide nephrograms were split up into a renal component and a component of the tissue background. New indices for the evaluation of renal function symmetry were proposed comprising the proportional determination of the effective renal plasma flow as well as of the symmetrical blood flow. For early diagnosis of latent renal dysfunction a new index is proposed characterizing the excretory renal transport as to local renal blood supply. Empirical indices of 120 patients suffering from chronic glomerulonephritis and pyelonephritis, resp., are stated

  6. Assessment of glomerular filtration rate and effective renal plasma flow in cystic fibrosis

    International Nuclear Information System (INIS)

    Spino, M.; Chai, R.P.; Isles, A.F.; Balfe, J.W.; Brown, R.G.; Thiessen, J.J.; MacLeod, S.M.

    1985-01-01

    A study was conducted to examine renal function in 10 healthy control subjects and eight patients with cystic fibrosis in stable condition. Sequential bolus injections of /sup 99m/Tc-DTPA and 125 I-OIH were administered to assess glomerular filtration rate and effective renal plasma flow, respectively. Blood was subsequently collected for 3 hours, and urine for 24 hours. Renal clearances of both radioisotope markers were virtually identical in patients and controls. Inasmuch as neither glomerular filtration rate nor effective renal plasma flow was enhanced in patients with cystic fibrosis, increased clearance of drugs in these patients is unlikely to be the result of enhanced glomerular filtration or tubular secretion

  7. Renal blood flow, early distal sodium, and plasma renin concentrations during osmotic diuresis

    DEFF Research Database (Denmark)

    Leyssac, P P; Holstein-Rathlou, N H; Skøtt, O

    2000-01-01

    .6 mmHg. Urine flow increased 10-fold, and sodium excretion increased by 177%. Plasma renin concentration (PRC) increased by 58%. Renal blood flow and glomerular filtration rate decreased, however end-proximal flow remained unchanged. After a similar volume of hypotonic glucose (152 mM), ED......(NaCl) increased by 3.6 mM, (P renal hemodynamics, urine flow, sodium excretion rate, or PRC. Infusion of 300 micromol NaCl in a smaller volume caused ED(NaCl) to increase by 6.4 mM without significant changes in PRC. Urine flow and sodium excretion increased significantly...

  8. Use of nonimaging nuclear medicine techniques to assess the effect of flunixin meglumine on effective renal plasma flow and effective renal blood flow in healthy horses.

    Science.gov (United States)

    Held, J P; Daniel, G B

    1991-10-01

    The effect of flunixin meglumine on renal function was studied in 6 healthy horses by use of nonimaging nuclear medicine techniques. Effective renal plasma flow (ERPF) and effective renal blood flow (ERBF) were determined by plasma clearance of 131I-orthoiodohippuric acid before and after administration of flunixin meglumine. Mean ERPF and ERBF was 6.03 ml/min/kg and 10.7 ml/min/kg, respectively, before treatment and was 5.7 ml/min/kg and 9.7 ml/min/kg, respectively, after treatment. Although ERPF and ERBF decreased after flunixin meglumine administration, the difference was not statistically significant.

  9. Increased kidney size, glomerular filtration rate and renal plasma flow in short-term insulin-dependent diabetics

    DEFF Research Database (Denmark)

    Christiansen, JS; Gammelgaard, J; Frandsen, M

    1981-01-01

    Glomerular filtration rate (GFR), renal plasma flow (RPF) and kidney volume were measured in thirteen male subjects (mean age 30 years) with short-term insulin-dependent diabetes (mean duration of disease 2.4 years) and fourteen normal male subjects (mean age 29 years). GFR and RPF were measured...

  10. Enhancement of glomerular filtration rate and renal plasma flow by oral glucose load in well controlled insulin-dependent diabetics

    DEFF Research Database (Denmark)

    Sandahl Christiansen, J; Christensen, C K; Hermansen, K

    1986-01-01

    Glomerular filtration rate (GFR) and renal plasma flow (RPF) were measured in 27 patients with uncomplicated insulin-dependent diabetes (IDDM) before and after an oral glucose load of 1.1 g glucose/kg body wt. In the 18 patients showing near-normoglycaemia (blood glucose less than or equal to 8....... No changes in blood pressure or urinary albumin excretion rates took place in either group. The reduction in plasma protein and in plasma growth hormone concentration were similar in the two groups. No change was seen in plasma arginine vasopressin concentration. There was no difference in the qualitative...

  11. Relationship between cardiac output and effective renal plasma flow in patients with cardiac disease

    Energy Technology Data Exchange (ETDEWEB)

    McGriffin, D; Tauxe, W N; Lewis, C; Karp, R; Mantle, J

    1984-12-01

    The relationship between effective renal plasma flow (ERPF) and cardiac output was examined in 46 patients (22 with congestive heart failure and 24 following cardiac surgical procedures) by simultaneously measuring the global ERPF by the single-injection method and cardiac output by the thermodilution method. Of the patients in the heart-failure group, 21 also had pulmonary artery end diastolic pressure (PAEDP) recorded at the same time. ERPF and cardiac output were found to be related by the regression equations: cardiac output = 2.08 + 0.0065 ERPF (r, 080), with a SE of estimate of 0.81 l/min. ERPF and PAEDP were related by the regression equation: PAEDP = 42.02 - 0.0675 ERPF (r, 0.86), with a SE of estimate of 5.5 mm Hg. ERPF may be a useful noninvasive method of estimating cardiac output if it is known that no intrinsic kidney disease is present, and if the error of 0.81 l/min (1 SE of estimate) is within the range of clinical usefulness. The error is principally attributable to the determination of cardiac output by the thermodilution method.

  12. Differential effect of T-type voltage-gated calcium channel disruption on renal plasma flow and glomerular filtration rate in vivo

    DEFF Research Database (Denmark)

    Thuesen, Anne D; Andersen, Henrik; Cardel, Majken

    2014-01-01

    Voltage-gated calcium channels (Cav) play an essential role in regulation of renal blood flow and GFR. Because T-type Cavs are differentially expressed in pre- and postglomerular vessels it was hypothesized that they impact renal blood flow and GFR differentially. The question was addressed by use...... of two T-type Cav knock-out mice strains. Continuous recordings of blood pressure and heart rate, and para-aminohippurate clearance (renal plasma flow) and inulin clearance (GFR) were performed in conscious, chronically catheterized, wild type and Cav 3.1-/- and Cav 3.2-/- mice. Contractility of afferent...... and efferent arterioles was determined in isolated perfused blood vessels. Efferent arterioles from Cav 3.2-/- mice constricted significantly more in response to a depolarization compared to Wt mice. GFR was increased in Cav 3.2-/- mice with no significant changes in renal plasma flow, heart rate and blood...

  13. Insulin-mediated increases in renal plasma flow are impaired in insulin-resistant normal subjects

    NARCIS (Netherlands)

    ter Maaten, JC; Bakker, SJL; Serne, EH; Moshage, HJ; Gans, ROB

    2000-01-01

    Background Impaired vasodilatation in skeletal muscle is a possible mechanism linking insulin resistance to blood pressure regulation. Increased renal vascular resistance has been demonstrated in the offspring of essential hypertensives. We assessed whether insulin-mediated renal vasodilatation is

  14. A randomized, controlled, double-blind crossover study on the effects of 2-L infusions of 0.9% saline and plasma-lyte® 148 on renal blood flow velocity and renal cortical tissue perfusion in healthy volunteers.

    Science.gov (United States)

    Chowdhury, Abeed H; Cox, Eleanor F; Francis, Susan T; Lobo, Dileep N

    2012-07-01

    We compared the effects of intravenous infusions of 0.9% saline ([Cl] 154 mmol/L) and Plasma-Lyte 148 ([Cl] 98 mmol/L, Baxter Healthcare) on renal blood flow velocity and perfusion in humans using magnetic resonance imaging (MRI). Animal experiments suggest that hyperchloremia resulting from 0.9% saline infusion may affect renal hemodynamics adversely, a phenomenon not studied in humans. Twelve healthy adult male subjects received 2-L intravenous infusions over 1 hour of 0.9% saline or Plasma-Lyte 148 in a randomized, double-blind manner. Crossover studies were performed 7 to 10 days apart. MRI scanning proceeded for 90 minutes after commencement of infusion to measure renal artery blood flow velocity and renal cortical perfusion. Blood was sampled and weight recorded hourly for 4 hours. Sustained hyperchloremia was seen with saline but not with Plasma-Lyte 148 (P Blood volume changes were identical (P = 0.867), but there was greater expansion of the extravascular fluid volume after saline (P = 0.029). There was a significant reduction in mean renal artery flow velocity (P = 0.045) and renal cortical tissue perfusion (P = 0.008) from baseline after saline, but not after Plasma-Lyte 148. There was no difference in concentrations of urinary neutrophil gelatinase-associated lipocalin after the 2 infusions (P = 0.917). This is the first human study to demonstrate that intravenous infusion of 0.9% saline results in reductions in renal blood flow velocity and renal cortical tissue perfusion. This has implications for intravenous fluid therapy in perioperative and critically ill patients. NCT01087853.

  15. Analyse of influence elements in the process of dynamic renal imaging to measure glomerular filtration rate and effective renal plasma flow in patients with type 2 diabetes mellitus

    International Nuclear Information System (INIS)

    Yao Lixin; Li Zuofei; Liu Bo; Guo Leiming

    2010-01-01

    Objective: To detect the changes and clinical influence elements of radionuclide renal dynamic imaging to measure glomerular filtration rate (GFR) and effective renal plasma flow (ERPF) in patients with type 2 diabetes mellitus (T2DM). Methods: One hundred and eight patients with T 2 DM were divided into 4 groups according to the values of urinary albumin excretion rate (UAER): Group I: UAER -1 , 31 cases. Group II: UAER 20∼200μg·min -1 , 28 cases. Group III: UAER >200μg·min -1 , serum creatinine(SCr) 200μg·min -1 , SCr≥ 105μmol/L, 23 cases. 99 Tc m -diethylenetriamine pentaacetic acid and 99 Tc m -ethylenedicysteine renal dynamic imaging were performed in all patients. GFR, ERPF and renogram were derived simultaneously. The levels of blood creatinine, blood urea nitrogen, urine albumin, blood press, fasting blood insulin, glycosylated hemoglobin, fasting blood glucousewere measured in the four groups. Results: With the evolvement of diabetes nephropathy (DN), UAERs were gradually ascended and the values of GFR and ERPF was gradually descended, the former offered remarkable inverse correlation with the two latters (r 1 = -0.497, P 2 =-0.215, P 1 =1.8, t 2 =2.1, t 3 =1.9, P 4 =3.2, P<0.01). Multielement stepwise regression analyses assumed that age, systolic pressure, glycosylated hemoglobin and insulin resistance index offered inverse correlation with GFR and ERPF (coefficient of regression factor: -0.507, -0.874, -0.528, -0.587, -0.336, -0.697, -0.348, -0.371, P<0.01). Conclusion: GFR and ERPF were sensitive index reflecting the changes of DN.Hypertension and insulin resistance were independence risk factors to make the value of GFR and ERPF decreased in patients with DN. (authors)

  16. Measurement of Effective Renal Plasma Flow: Evaluation of Clinical Uses in Combination with Renography

    Energy Technology Data Exchange (ETDEWEB)

    Mahadev, V. [Department of Radiotherapy and Nuclear Medicine, General Hospital, Kuala Lumpur (Malaysia)

    1971-02-15

    A comparison of techniques for measuring the renal clearance of Hippuran using a single injection of {sup 131}I sodium orthoiodohippurate in 30 normal subjects and 49 patients showed that a simplified technique using limited samples of blood gave comparable results to more complicated blood and external monitoring techniques without significant loss of accuracy. The clearance value in normal subjects was 645 ml/1.73 m{sup 2} ({+-} 108 ml) and is comparable with results obtained elsewhere. Together with a renogram examination this measurement enables more information to be obtained and helps to distinguish vascular and parenchymal disorders from purely obstructive lesions. It may be useful in the problem of renal tuberculosis and in distinguishing benign kidney lesions from malignant. (author)

  17. Enhancement of glomerular filtration rate and renal plasma flow by oral glucose load in well controlled insulin-dependent diabetics

    DEFF Research Database (Denmark)

    Sandahl Christiansen, J; Christensen, C K; Hermansen, K

    1986-01-01

    Glomerular filtration rate (GFR) and renal plasma flow (RPF) were measured in 27 patients with uncomplicated insulin-dependent diabetes (IDDM) before and after an oral glucose load of 1.1 g glucose/kg body wt. In the 18 patients showing near-normoglycaemia (blood glucose less than or equal to 8...... mmol/l) before the glucose challenge the increase in blood glucose from 4.2 +/- 1.7 to 15.2 +/- 2.3 mmol/l was accompanied by an enhancement of GFR from 128 +/- 15 to 132 +/- 14 ml/min X 1.73 m2 (2p = 0.030) and of RPF from 534 +/- 116 to 562 +/- 105 ml/min X 1.73 m2 (2p = 0.023). By contrast oral...... glucose load to the nine patients with hyperglycaemia (greater than 8 mmol/l) during baseline conditions raising blood glucose from 11.9 +/- 2.0 to 19.6 +/- 1.5 mmol/l was accompanied by a reduction in GFR from 149 +/- 15 to 139 +/- 9 ml/min X 1.73 m2 (2p less than 0.001) while RPF was unchanged...

  18. Simultaneous Determination of Glomerular Filtration Rate with {sup 125}I-Iothalamate and Effective Renal Plasma Flow with {sup 131}I-Hippuran

    Energy Technology Data Exchange (ETDEWEB)

    Houwen, B.; Donker, A. J.M.; Woldring, M. G.; Beekhuis, H.; Zanten, A.K. van; Looye, A.; Hem, G.K. van der [Department Of Internal Medicine, Central Isotope Laboratory, University of Groningen, Groningen (Netherlands)

    1971-02-15

    The glomerular filtration rate (GFR) and effective renal plasma flow (ERPF) were measured in patients with normal and abnormal renal functions. {sup 125}I-iothalamate and inulin were used for the estimation of the GFR; {sup 131}I-Hippuran, p-aminohippuric acid and p-acetylaminohippuric acid were used for the ERPF determination. Procedure involved the continuous infusion of a solution containing {sup 125}I-iothalamate, {sup 131}I-Hippuran, inulin and PAH or PACAH, intravenously administered by an infusion pump. The clearances were determined in two ways: (1) By means of the standard technique, i.e. the equation, (urine concentration x urine volume)/plasma concentration: (2) By using the equation, intravenous dose per minute/plasma concentration. Comparisons between the methods are made. (author)

  19. [Influence of non-sodium restricted diet with diuretics on plasma rennin, renal blood flow and in patients with cirrhotic ascites].

    Science.gov (United States)

    Zhu, Yin-fang; Gu, Xi-bing; Zhu, Hong-ying; Yang, Xiao-juan; Wang, Dong; Yu, Ping

    2013-02-01

    To explore influence of sodium restricted diet and non-sodium restricted diet on plasma rennin (PRA), angiotensin II (All), ALD, renal blood flow (RBF) and subside of ascites in patients with cirrhotic ascites. Eighty cases of hepatitis B with cirrhotic ascites were randomly divided into sodium restricted diet group and non-sodium restricted diet group. 39 cases were in non-sodium restricted diet group, taking sodium chloride 6500-8000 mg daily; 41 cases were in sodium restricted diet group, taking sodium chloride 5000 mg daily. Both groups received diuretics furosemide and spironolactone. Blood sodium, urine sodium, PRA, AII, ALD, RBF ascites subsiding were compared after treatment. In non-sodium restricted diet group, blood sodium and urine sodium increased 10 days after treatment compared with those before treatment, and compared with those of sodium restricted diet group 10 days after treatment, P Renal damage induced by low blood sodium after treatment was less in non-sodium restricted diet group than that in sodium restricted diet group, P blood sodium, thus increasing excretion of urine sodium and diuretic effect. It can also decrease levels of PRA, AII and ALD, increase renal blood flow and prevent renal damage induced by low blood sodium and facilitate subsiding of ascites.

  20. The investigation of in-vivo measurement of individual renal blood perfusion, effective renal plasma flow and quantitation of renogram and 15 min bladder collection percentage

    International Nuclear Information System (INIS)

    Huang Kangchu

    1991-01-01

    25 normals and 43 renal diseases were examined by the RBF-I multifunctioning renography. The result showed that the determination of ERPF has no difference between blood sampling and noin-blood sampling method, and actually the lattrer can replace the former one. Above method can be also used for the measurement of the individual renal blood perfusion, the quantitation of renogram and the 15 min bladder coolection percentage at the same time. Thereby it provides more complete diagnostic information for the renal vascular diseases, renal pancren chymations and other urologic diseases

  1. Two-compartment, two-sample technique for accurate estimation of effective renal plasma flow: Theoretical development and comparison with other methods

    International Nuclear Information System (INIS)

    Lear, J.L.; Feyerabend, A.; Gregory, C.

    1989-01-01

    Discordance between effective renal plasma flow (ERPF) measurements from radionuclide techniques that use single versus multiple plasma samples was investigated. In particular, the authors determined whether effects of variations in distribution volume (Vd) of iodine-131 iodohippurate on measurement of ERPF could be ignored, an assumption implicit in the single-sample technique. The influence of Vd on ERPF was found to be significant, a factor indicating an important and previously unappreciated source of error in the single-sample technique. Therefore, a new two-compartment, two-plasma-sample technique was developed on the basis of the observations that while variations in Vd occur from patient to patient, the relationship between intravascular and extravascular components of Vd and the rate of iodohippurate exchange between the components are stable throughout a wide range of physiologic and pathologic conditions. The new technique was applied in a series of 30 studies in 19 patients. Results were compared with those achieved with the reference, single-sample, and slope-intercept techniques. The new two-compartment, two-sample technique yielded estimates of ERPF that more closely agreed with the reference multiple-sample method than either the single-sample or slope-intercept techniques

  2. Nonlinear interactions in renal blood flow regulation

    DEFF Research Database (Denmark)

    Marsh, Donald J.; Sosnovtseva, Olga; Chon, Ki H.

    2005-01-01

    We have developed a model of tubuloglomerular feedback (TGF) and the myogenic mechanism in afferent arterioles to understand how the two mechanisms are coupled. This paper presents the model. The tubular model predicts pressure, flow, and NaCl concentration as functions of time and tubular length...... hydrostatic pressure, and plasma flow rate. The arteriolar model predicts fraction of open K channels, intracellular Ca concentration (Ca-i), potential difference, rate of actin - myosin cross bridge formation, force of contraction, and length of elastic elements, and was solved for two arteriolar segments...... resistance and glomerular capillary pressure. The model couples TGF input to voltage-gated Ca channels. It predicts autoregulation of GFR and renal blood flow, matches experimental measures of tubular pressure and macula densa NaCl concentration, and predicts TGF-induced oscillations and a faster smaller...

  3. Assessing the kidney function parameters glomerular filtration rate and effective renal plasma flow with dynamic FDG-PET/MRI in healthy subjects.

    Science.gov (United States)

    Geist, Barbara K; Baltzer, Pascal; Fueger, Barbara; Hamboeck, Martina; Nakuz, Thomas; Papp, Laszlo; Rasul, Sazan; Sundar, Lalith Kumar Shiyam; Hacker, Marcus; Staudenherz, Anton

    2018-05-09

    A method was developed to assess the kidney parameters glomerular filtration rate (GFR) and effective renal plasma flow (ERPF) from 2-deoxy-2-[ 18 F]fluoro-D-glucose (FDG) concentration behavior in kidneys, measured with positron emission tomography (PET) scans. Twenty-four healthy adult subjects prospectively underwent dynamic simultaneous PET/magnetic resonance imaging (MRI) examination. Time activity curves (TACs) were obtained from the dynamic PET series, with the guidance of MR information. Patlak analysis was performed to determine the GFR, and based on integrals, ERPF was calculated. Results were compared to intra-individually obtained reference values determined from venous blood samples. Total kidney GFR and ERPF as estimated by dynamic PET/MRI were highly correlated to their reference values (r = 0.88/p dynamic FDG PET/MRI scans in healthy kidneys. This has advantages for patients getting a routine scan, where additional examinations for kidney function estimation could be avoided. Further studies are required for transferring this PET/MRI method to PET/CT applications.

  4. Plasma protein haptoglobin modulates renal iron loading

    DEFF Research Database (Denmark)

    Fagoonee, Sharmila; Gburek, Jakub; Hirsch, Emilio

    2005-01-01

    Haptoglobin is the plasma protein with the highest binding affinity for hemoglobin. The strength of hemoglobin binding and the existence of a specific receptor for the haptoglobin-hemoglobin complex in the monocyte/macrophage system clearly suggest that haptoglobin may have a crucial role in heme...... distribution of hemoglobin in haptoglobin-deficient mice resulted in abnormal iron deposits in proximal tubules during aging. Moreover, iron also accumulated in proximal tubules after renal ischemia-reperfusion injury or after an acute plasma heme-protein overload caused by muscle injury, without affecting...... morphological and functional parameters of renal damage. These data demonstrate that haptoglobin crucially prevents glomerular filtration of hemoglobin and, consequently, renal iron loading during aging and following acute plasma heme-protein overload....

  5. [Plasma cell dyscrasias and renal damage].

    Science.gov (United States)

    Pasquali, Sonia; Iannuzzella, Francesco; Somenzi, Danio; Mattei, Silvia; Bovino, Achiropita; Corradini, Mattia

    2012-01-01

    Kidney damage caused by immunoglobulin free light chains in the setting of plasma cell dyscrasias is common and may involve all renal compartments, from the glomerulus to the tubulointerstitium, in a wide variety of histomorphological and clinical patterns. The knowledge of how free light chains can promote kidney injury is growing: they can cause functional changes, be processed and deposited, mediate inflammation, apoptosis and fibrosis, and obstruct nephrons. Each clone of the free light chain is unique and its primary structure and post-translation modification can determine the type of renal disease. Measurement of serum free light chain concentrations and calculation of the serum kappa/lambda ratio, together with renal biopsy, represent essential diagnostic tools. An early and correct diagnosis of renal lesions due to plasma cell dyscrasias will allow early initiation of disease-specific treatment strategies. The treatment of free light chain nephropathies is evolving and knowledge of the pathways that promote renal damage should lead to further therapeutic developments.

  6. A randomized, controlled, double-blind crossover study on the effects of 1-L infusions of 6% hydroxyethyl starch suspended in 0.9% saline (voluven) and a balanced solution (Plasma Volume Redibag) on blood volume, renal blood flow velocity, and renal cortical tissue perfusion in healthy volunteers.

    Science.gov (United States)

    Chowdhury, Abeed H; Cox, Eleanor F; Francis, Susan T; Lobo, Dileep N

    2014-05-01

    We compared the effects of intravenous administration of 6% hydroxyethyl starch (maize-derived) in 0.9% saline (Voluven; Fresenius Kabi, Runcorn, United Kingdom) and a "balanced" preparation of 6% hydroxyethyl starch (potato-derived) [Plasma Volume Redibag (PVR); Baxter Healthcare, Thetford, United Kingdom] on renal blood flow velocity and renal cortical tissue perfusion in humans using magnetic resonance imaging. Hyperchloremia resulting from 0.9% saline infusion may adversely affect renal hemodynamics when compared with balanced crystalloids. This phenomenon has not been studied with colloids. Twelve healthy adult male subjects received 1-L intravenous infusions of Voluven or PVR over 30 minutes in a randomized, double-blind manner, with crossover studies 7 to 10 days later. Magnetic resonance imaging proceeded for 60 minutes after commencement of infusion to measure renal artery blood flow velocity and renal cortical perfusion. Blood was sampled, and weight was recorded at 0, 30, 60, 120, 180, and 240 minutes. Mean peak serum chloride concentrations were 108 and 106 mmol/L, respectively, after Voluven and PVR infusion (P = 0.032). Changes in blood volume (P = 0.867), strong ion difference (P = 0.219), and mean renal artery flow velocity (P = 0.319) were similar. However, there was a significant increase in mean renal cortical tissue perfusion after PVR when compared with Voluven (P = 0.033). There was no difference in urinary neutrophil gelatinase-associated liopcalin to creatinine ratios after the infusion (P = 0.164). There was no difference in the blood volume-expanding properties of the 2 preparations of 6% hydroxyethyl starch. The balanced starch produced an increase in renal cortical tissue perfusion, a phenomenon not seen with starch in 0.9% saline.

  7. Dust in flowing magnetized plasma

    International Nuclear Information System (INIS)

    Pandey, Birendra P.; Samarian, Alex A.; Vladimirov, Sergey V.

    2009-01-01

    Plasma flows occur in almost every laboratory device and interactions of flowing plasmas with near-wall impurities and/or dust significantly affects the efficiency and lifetime of such devices. The charged dust inside the magnetized flowing plasma moves primarily under the influence of the plasma drag and electric forces. Here, the charge on the dust, plasma potential, and plasma density are calculated self-consistently. The electrons are assumed non-Boltzmannian and the effect of electron magnetization and electron-atom collisions on the dust charge is calculated in a self-consistent fashion. For various plasma magnetization parameters viz. the ratio of the electron and ion cyclotron frequencies to their respective collision frequencies, plasma-atom and ionization frequencies, the evolution of the plasma potential and density in the flow region is investigated. The variation of the dust charge profile is shown to be a sensitive function of plasma parameters. (author)

  8. Nutrient and nonnutrient renal blood flow

    International Nuclear Information System (INIS)

    Young, J.S.; Passmore, J.C.; Hartupee, D.A.; Baker, C.H.

    1990-01-01

    The role of prostaglandins in the distribution of total renal blood flow (TRBF) between nutrient and nonnutrient compartments was investigated in anesthetized mongrel dogs. Renal blood flow distribution was assessed by the xenon 133 freeze-dissection technique and by rubidium 86 extraction after ibuprofen treatment. Ibuprofen (13 mg/kg) significantly decreased TRBF by 16.3% +/- 1.2% (mean +/- SEM electromagnetic flow probe; p less than 0.005), but did not alter blood flows to the outer cortex (3.7 vs 4.3 ml/min per gram), the inner cortex (2.6 vs 2.7 ml/min per gram), and the other medulla (1.5 vs 1.5 ml/min per gram), which suggests a decrease in nonnutrient flow. In a separate group of animals the effect of reduced blood flow on the nutrient and nonnutrient components was determined by mechanically reducing renal arterial blood flow by 48%. Unlike the ibuprofen group, nutrient blood flows were proportionally reduced with the mechanical decrease in TRBF in the outer cortex (1.9 ml/min per gram, p less than 0.05), the inner cortex (1.4 ml/min per gram, p less than 0.05), and the outer medulla (0.8 ml/min per gram, p less than 0.01). These results indicate no shift between nutrient and nonnutrient compartments. Nutrient and nonnutrient renal blood flows of the left kidney were also determined by 86Rb extraction. After ibuprofen treatment, nonextracted 86Rb decreased to 12.1% from the control value of 15.6% (p less than 0.05). Mechanical reduction of TRBF did not significantly decrease the proportion of unextracted 86Rb (18.7%)

  9. A comparison of two nuclear-medical techniques for effective renal plasma flow determination in rabbits: Radiation controlled infusion-pump and whole-body measurement according to Oberhausen

    International Nuclear Information System (INIS)

    Mayer-Wehrstein, R.

    1981-01-01

    Two nuclear techniques were investigated for determination of the effective renal plasma flow with J-131-Hippuran in rabbits: whole-body measurement according to Oberhausen and clearance determination with a radiation controlled feed back infusion pump. In the first method the clearance determination follows after a single injection of the testing substance in the decreasing phase of the blood level, in the second method a constant blood level of the testing substance is maintained. A technique was developed for the determination of the blood-tissue ratio by considering the values determined by the constant blood level. This way the exact clearance values were computet for the decreasing plasma level. Nineteen clearance determinations were performed in rabbits altogether. (orig.) [de

  10. MR velocity mapping measurement of renal artery blood flow in patients with impaired kidney function

    DEFF Research Database (Denmark)

    Cortsen, M; Petersen, L.J.; Stahlberg, F

    1996-01-01

    Renal blood flow (RBF) was measured in 9 patients with chronic impaired kidney function using MR velocity mapping and compared to PAH clearance and 99mTc-DTPA scintigraphy. An image plane suitable for flow measurement perpendicular to the renal arteries was chosen from 2-dimensional MR angiography....... MR velocity mapping was performed in both renal arteries using an ECG-triggered gradient echo pulse sequence previously validated in normal volunteers. Effective renal plasma flow was calculated from the clearance rate of PAH during constant infusion and the split of renal function was evaluated...... by 99mTc-DTPA scintigraphy. A reduction of RBF was found, and there was a significant correlation between PAH clearance multiplied by 1/(1-hematocrit) and RBF determined by MR velocity mapping. Furthermore, a significant correlation between the distribution of renal function and the percent distribution...

  11. Renal blood flow and metabolism after cold ischaemia

    DEFF Research Database (Denmark)

    Henriksen, J H; Petersen, H K

    1984-01-01

    Peroperative measurements of renal blood flow (RBF), renal O2-uptake, and renal venous lactate/pyruvate (L/P) ratio were performed before and after a period of 30-71 min of hypothermic (10-15 degrees C) renal ischaemia in nine patients, undergoing surgery for renal calculi. Before ischaemia, RBF.......01) immediately after re-established perfusion and 36% (P less than 0.02) 30 min later. In one additional patient, who had a short warm ischaemia (8 min), the flow pattern was the same. As arterial pressure remained constant, the reduced RBF signifies an increased renal vascular resistance. Renal O2-uptake...... and renal venous L/P ratio were almost constant, indicating no significant anaerobic processes being involved in the flow response. None of the patients showed any signs of reactive hyperaemia. It is concluded that hypothermic renal ischaemia may be followed by an increased renal vascular resistance even...

  12. Renal Blood Flow, Glomerular Filtration Rate, and Renal Oxygenation in Early Clinical Septic Shock.

    Science.gov (United States)

    Skytte Larsson, Jenny; Krumbholz, Vitus; Enskog, Anders; Bragadottir, Gudrun; Redfors, Bengt; Ricksten, Sven-Erik

    2018-06-01

    Data on renal hemodynamics, function, and oxygenation in early clinical septic shock are lacking. We therefore measured renal blood flow, glomerular filtration rate, renal oxygen consumption, and oxygenation in patients with early septic shock. Prospective comparative study. General and cardiothoracic ICUs. Patients with norepinephrine-dependent early septic shock (n = 8) were studied within 24 hours after arrival in the ICU and compared with postcardiac surgery patients without acute kidney injury (comparator group, n = 58). None. Data on systemic hemodynamics and renal variables were obtained during two 30-minute periods. Renal blood flow was measured by the infusion clearance of para-aminohippuric acid, corrected for renal extraction of para-aminohippuric acid. Renal filtration fraction was measured by renal extraction of chromium-51 labeled EDTA. Renal oxygenation was estimated from renal oxygen extraction. Renal oxygen delivery (-24%; p = 0.037) and the renal blood flow-to-cardiac index ratio (-21%; p = 0.018) were lower, renal vascular resistance was higher (26%; p = 0.027), whereas renal blood flow tended to be lower (-19%; p = 0.068) in the septic group. Glomerular filtration rate (-32%; p = 0.006) and renal sodium reabsorption (-29%; p = 0.014) were both lower in the septic group. Neither renal filtration fraction nor renal oxygen consumption differed significantly between groups. Renal oxygen extraction was significantly higher in the septic group (28%; p = 0.022). In the septic group, markers of tubular injury were elevated. In early clinical septic shock, renal function was lower, which was accompanied by renal vasoconstriction, a lower renal oxygen delivery, impaired renal oxygenation, and tubular sodium reabsorption at a high oxygen cost compared with controls.

  13. Probing of flowing electron plasmas

    International Nuclear Information System (INIS)

    Himura, H.; Nakashima, C.; Saito, H.; Yoshida, Z.

    2001-01-01

    Probing of streaming electron plasmas with finite temperature is studied. For the first time, a current-voltage characteristic of an electric probe is measured in electron plasmas. Due to the fast flow of the electron plasmas, the characteristic curve spreads out significantly and exhibits a long tail. This feature can be explained calculating the currents collected to the probe. In flowing electron plasmas, the distribution function observed in the laboratory frame is non-Maxwellian even if the plasmas come to a state of thermal equilibrium. Another significant feature of the characteristic is that it determines a floating potential where the current equals zero, despite there being very few ions in the electron plasma. A high impedance probe, which is popularly used to determine the space potential of electron plasmas, outputs the potential. The method is available only for plasmas with density much smaller than the Brillouin limit

  14. Experimental studies of renal blood flow by digitized functional angiography

    International Nuclear Information System (INIS)

    Buersch, J.H.; Ochs, C.; Hahne, H.J.; Heintzen, P.H.

    1985-01-01

    New techniques of digital image processing have been experimentally tested for the assessment of renal blood flow. The underlying principle in functional angiography is the extraction of flow parameters. Basically, density-time variations of the contrast medium are analayzed from to each picture element of a 256x256 matrix. The real-time acquisition rate of images was 25/sec. For the calculation of angiographic flow a PDP 11/40 computer was used to interactively perform a time dependent segmentation of the renal arteries and the aorta. Subsequently, volume flow was calculated in relative units for the specific vascular segments under study. 15 control angiograms were made in 5 animals with cardiac output ranging between 0.8 to 2.2l/min. Unilateral renal blood flow was calculated as 24+-3.4% of pre-renal aortic flow without systematic side differences. Reproducibility from repeated flow measurements showed an SD of +-1.8% of the individual pre-renal aortic flow. Renal flow was also measured in 3 animals with an experimentally created 50% flow reduction of the left kidney. Angiographic flow in the left renal artery dropped to 12+-2% of pre-renal flow. The present experimental data suggest that digital angiography has sufficient diagnostic capabilities for the detection of abnormal renal blood flow. The technique may serve as a useful diagnostic adjunct to conventional angiography and has the potential of assisting in the evaluation of renal vascular hypertension. (orig.) [de

  15. Doppler Flow Wire Evaluation of Renal Blood Flow Reserve in Hypertensive Patients with Normal Renal Arteries

    International Nuclear Information System (INIS)

    Beregi, Jean-Paul; Mounier-Vehier, Claire; Devos, Patrick; Gautier, Corinne; Libersa, Christian; McFadden, Eugene P.; Carre, Alain

    2000-01-01

    Purpose: To study the vasomotor responses of the renal microcirculation in patients with essential hypertension.Methods: We studied the reactivity of the renal microcirculation to papaverine, with intraarterial Doppler and quantitative arteriography, in 34 renal arteries of 19 hypertensive patients without significant renal artery stenosis. Isosorbide dinitrate was given to maximally dilate proximal renal arteries. APV (average peak blood flow velocity) was used as an index of renal blood flow.Results: Kidneys could be divided into two distinct subgroups based on their response to papaverine. An increase in APV of up to 55% occurred in 21 kidneys, an increase > 55% in 13 kidneys. Within each group the values were normally distributed. Both baseline APV and the effect of papaverine on mean velocity differed significantly between groups.Conclusion: There seems to be a subgroup of patients with essential hypertension that has an impaired reactivity to papaverine, consistent with a functional impairment of the renal microcirculation. Further studies are required to determine whether this abnormality contributes to or results from elevated blood pressure

  16. Frequency encoding in renal blood flow regulation

    DEFF Research Database (Denmark)

    Marsh, D.J.; Sosnovtseva, Olga; Pavlov, A.N.

    2005-01-01

    With a model of renal blood flow regulation, we examined consequences of tubuloglomerular feedback (TGF) coupling to the myogenic mechanism via voltage-gated Ca channels. The model reproduces the characteristic oscillations of the two mechanisms and predicts frequency and amplitude modulation...... of the myogenic oscillation by TGF. Analysis by wavelet transforms of single-nephron blood flow confirms that both amplitude and frequency of the myogenic oscillation are modulated by TGF. We developed a double-wavelet transform technique to estimate modulation frequency. Median value of the ratio of modulation...... TGF cycle to the next. We used a blood pressure signal recorded by telemetry from a conscious rat as the input to the model. Blood pressure fluctuations induced variability in the modulation records similar to those found in the nephron blood flow results. Frequency and amplitude modulation can...

  17. Relaxed states with plasma flow

    International Nuclear Information System (INIS)

    Avinash, K.; Taylor, J.B.

    1991-01-01

    In the theory of relaxation, a turbulent plasma reaches a state of minimum energy subject to constant magnetic helicity. In this state the plasma velocity is zero. Attempts have been made by introducing a number of different constraints, to obtain relaxed states with plasma flow. It is shown that these alternative constraints depend on two self-helicities, one for ions, and one for electrons. However, whereas there are strong arguments for the effective invariance of the original magnetic-helicity, these arguments do not apply to the self-helicities. Consequently the existence of relaxed states with flow remains in doubt. (author)

  18. Noninvasive measurement of an index of renal blood flow

    International Nuclear Information System (INIS)

    Powers, T.A.; Rees, R.S.; Bowen, R.D.

    1983-01-01

    A new technique for the noninvasive measurement of an index of renal blood flow is described. The method utilizes ultrasound determined renal volume and radionuclide assessment of the mean transit time of a pertechnetate bolus through the kidneys. From this information a value for flow is calculated according to compartmental analysis principles. There is good correlation between renal blood flow estimated by this technique and that determined by microsphere injection

  19. Plasma exchange for renal vasculitis and idiopathic rapidly progressive glomerulonephritis: a meta-analysis

    DEFF Research Database (Denmark)

    Walsh, Michael; Catapano, Fausta; Szpirt, Wladimir

    2011-01-01

    Plasma exchange may be effective adjunctive treatment for renal vasculitis. We performed a systematic review and meta-analysis of randomized controlled trials of plasma exchange for renal vasculitis.......Plasma exchange may be effective adjunctive treatment for renal vasculitis. We performed a systematic review and meta-analysis of randomized controlled trials of plasma exchange for renal vasculitis....

  20. Renal I-131-hippurate clearance overestimates true renal blood flow in the instrumented conscious dog

    NARCIS (Netherlands)

    Visscher, CA; DeZeeuw, D; Navis, G; VanZanten, AK; DeJong, PE; Huisman, RM

    We evaluated renal I-131-hippurate clearance (ERPF(hip)) as a measure of renal blood flow (RBF) in chronically instrumented conscious dogs. When adjusted for renal hippurate extraction (E(hip), 0.77 +/- 0.01) and hematocrit (Hct, 39.7 +/- 1%), calculated RBF(hip) (656 +/- 37 ml/min) markedly

  1. Flow visualisation study of spiral flow in the aorta-renal bifurcation.

    Science.gov (United States)

    Fulker, David; Javadzadegan, Ashkan; Li, Zuming; Barber, Tracie

    2017-10-01

    The aim of this study was to analyse the flow dynamics in an idealised model of the aorta-renal bifurcation using flow visualisation, with a particular focus on the effect of aorta-to-renal flow ratio and flow spirality. The recirculation length was longest when there was low flow in the renal artery and smaller in the presence of spiral flow. The results also indicate that patients without spiral flow or who have low flow in the renal artery due to the presence of stenosis may be susceptible to heightened development of atherosclerotic lesions.

  2. Recirculation zone length in renal artery is affected by flow spirality and renal-to-aorta flow ratio.

    Science.gov (United States)

    Javadzadegan, Ashkan; Fulker, David; Barber, Tracie

    2017-07-01

    Haemodynamic perturbations such as flow recirculation zones play a key role in progression and development of renal artery stenosis, which typically originate at the aorta-renal bifurcation. The spiral nature of aortic blood flow, division of aortic blood flow in renal artery as well as the exercise conditions have been shown to alter the haemodynamics in both positive and negative ways. This study focuses on the combinative effects of spiral component of blood flow, renal-to-aorta flow ratio and the exercise conditions on the size and distribution of recirculation zones in renal branches using computational fluid dynamics technique. Our findings show that the recirculation length was longest when the renal-to-aorta flow ratio was smallest. Spiral flow and exercise conditions were found to be effective in reducing the recirculation length in particular in small renal-to-aorta flow ratios. These results support the hypothesis that in renal arteries with small flow ratios where a stenosis is already developed an artificially induced spiral flow within the aorta may decelerate the progression of stenosis and thereby help preserve kidney function.

  3. Comparison of measurement of 99mTc-MAG3 plasma clearance by single plasma sample and renal uptake ratio

    International Nuclear Information System (INIS)

    Ushijima, Yo; Sugihara, Hiroki; Okuyama, Chio; Okitsu, Sigeyuki; Nii, Takeshi; Nishida, Takuji; Okamoto, Kunio; Maeda, Tomoho

    1997-01-01

    Measurement of 99m Tc-MAG 3 plasma clearance based on one-compartment model (MPC method) is a non-invasive method using the renal uptake ratio. We evaluated the clinical usefulness of this method, compared with effective renal plasma flow (ERPF) using 123 I-OIH and two single-plasma sample methods using 99m Tc-MAG 3 (Russell method and Bubeck method). The ratio of 99m Tc-MAG 3 clearance to ERPF was 1.00±0.26. MPC method correlated well with Russell and Bubeck methods (r=0.904, r=0.897). We conclude that MPC method is a suitable replacement for single-plasma sample method in routine clinical use. (author)

  4. Simple technique for measuring relative renal blood flow

    International Nuclear Information System (INIS)

    Shames, D.M.; Korobkin, M.

    1976-01-01

    To determine whether externally monitored early renal uptake of 131 I-hippurate is proportional to renal blood flow, the renal uptake of 131 -hippurate at 1 to 2 min after injection was compared with the renal accumulation of radioactive carbonized microspheres in dogs. A renal artery catheter equipped with a balloon was used to decrease renal blood flow unilaterally. One minute after the intravenous injection of 100 μCi of 131 I-hippurate, about 1 μCi of either 85 Sr- or 95 Nb-labeled carbon microspheres was injected into the left ventricle. Radioactivity was measured over both kidneys. The total radioactivity within each kidney region of interest was corrected for background and integrated over the 1 to 2 min interval after injection. Thirteen measurements of relative renal blood flow were made for seven dogs. The dogs were then killed and both kidneys were excised and counted for the radioactivity of the microspheres. The 1 to 2-min relative renal uptake of 131 I-hippurate correlated well with relative microsphere uptake, suggesting that relative renal blood flow can be simply determined from the external measurements of renal uptake of 131 I-hippurate

  5. Renal blood flow in sepsis: a complex issue

    OpenAIRE

    Molitoris, Bruce A

    2005-01-01

    The clinical complexity of sepsis and the regional variability in renal blood flow present a difficult challenge for the clinician or investigator in understanding the role and clinical importance of reduced blood flow in the pathophysiology of sepsis-induced acute renal failure. Understanding the role of regional microvasculature flow and interactions between endothelium and white blood cells in the local delivery of oxygen and substrates is of critical importance. Therefore, measuring total...

  6. Spiral blood flow in aorta-renal bifurcation models.

    Science.gov (United States)

    Javadzadegan, Ashkan; Simmons, Anne; Barber, Tracie

    2016-01-01

    The presence of a spiral arterial blood flow pattern in humans has been widely accepted. It is believed that this spiral component of the blood flow alters arterial haemodynamics in both positive and negative ways. The purpose of this study was to determine the effect of spiral flow on haemodynamic changes in aorta-renal bifurcations. In this regard, a computational fluid dynamics analysis of pulsatile blood flow was performed in two idealised models of aorta-renal bifurcations with and without flow diverter. The results show that the spirality effect causes a substantial variation in blood velocity distribution, while causing only slight changes in fluid shear stress patterns. The dominant observed effect of spiral flow is on turbulent kinetic energy and flow recirculation zones. As spiral flow intensity increases, the rate of turbulent kinetic energy production decreases, reducing the region of potential damage to red blood cells and endothelial cells. Furthermore, the recirculation zones which form on the cranial sides of the aorta and renal artery shrink in size in the presence of spirality effect; this may lower the rate of atherosclerosis development and progression in the aorta-renal bifurcation. These results indicate that the spiral nature of blood flow has atheroprotective effects in renal arteries and should be taken into consideration in analyses of the aorta and renal arteries.

  7. Eppur Si Muove: The dynamic nature of physiological control of renal blood flow by the renal sympathetic nerves.

    Science.gov (United States)

    Schiller, Alicia M; Pellegrino, Peter Ricci; Zucker, Irving H

    2017-05-01

    Tubuloglomerular feedback and the myogenic response are widely appreciated as important regulators of renal blood flow, but the role of the sympathetic nervous system in physiological renal blood flow control remains controversial. Where classic studies using static measures of renal blood flow failed, dynamic approaches have succeeded in demonstrating sympathetic control of renal blood flow under normal physiological conditions. This review focuses on transfer function analysis of renal pressure-flow, which leverages the physical relationship between blood pressure and flow to assess the underlying vascular control mechanisms. Studies using this approach indicate that the renal nerves are important in the rapid regulation of the renal vasculature. Animals with intact renal innervation show a sympathetic signature in the frequency range associated with sympathetic vasomotion that is eliminated by renal denervation. In conscious rabbits, this sympathetic signature exerts vasoconstrictive, baroreflex control of renal vascular conductance, matching well with the rhythmic, baroreflex-influenced control of renal sympathetic nerve activity and complementing findings from other studies employing dynamic approaches to study renal sympathetic vascular control. In this light, classic studies reporting that nerve stimulation and renal denervation do not affect static measures of renal blood flow provide evidence for the strength of renal autoregulation rather than evidence against physiological renal sympathetic control of renal blood flow. Thus, alongside tubuloglomerular feedback and the myogenic response, renal sympathetic outflow should be considered an important physiological regulator of renal blood flow. Clinically, renal sympathetic vasomotion may be important for solving the problems facing the field of therapeutic renal denervation. Copyright © 2016 Elsevier B.V. All rights reserved.

  8. Radionuclide evaluation of renal transplants

    International Nuclear Information System (INIS)

    Yang Hong; Zhao Deshan

    2000-01-01

    Radionuclide renal imaging and plasma clearance methods can quickly quantitate renal blood flow and function in renal transplants. They can diagnose acute tubular necrosis and rejection, renal scar, surgical complications such as urine leaks, obstruction and renal artery stenosis after renal transplants. At the same time they can assess the therapy effect of renal transplant complications and can also predict renal transplant survival from early post-operative function studies

  9. Renal blood flow after selective injection of different dosages of diatrizoate into the renal artery

    International Nuclear Information System (INIS)

    Burgener, F.A.; Fischer, H.W.; Weber, D.A.

    1975-01-01

    The characteristic biphasic renal haemodynamic response to diatrizoate injected into the renal artery was shown in the dog with the 133-xenon washout technique. A brief increase in renal blood flow (RBF) during the first ten seconds is followed by a more prolonged period of diminuished RBF. A dose of 4 ml. diatrizoate 60% resulted in the maximum RBF increase of 43% after ten seconds, but even 1 ml. diatrizoate raised the RBF 24%. The initial vasodilator effect of diatrizoate compares well in its extent with the most potent renal vasodilators. (orig.) [de

  10. The impact of intrarenal nitric oxide synthase inhibition on renal blood flow and function in mild and severe hyperdynamic sepsis.

    Science.gov (United States)

    Ishikawa, Ken; Bellomo, Rinaldo; May, Clive N

    2011-04-01

    In experimental hyperdynamic sepsis, renal function deteriorates despite renal vasodilatation and increased renal blood flow. Because nitric oxide is increased in sepsis and participates in renal blood flow control, we investigated the effects of intrarenal Nω-nitro-L-arginine methyl ester, a nonspecific nitric oxide synthase inhibitor, in mild and severe sepsis. Prospective crossover and randomized control interventional studies. University-affiliated research institute. Thirty-two merino ewes. Examination of responses to intrarenal infusion of Nω-nitro-L-arginine methyl ester for 8 hrs in unilaterally nephrectomized normal sheep and in sheep administered Escherichia coli. : In normal sheep, Nω-nitro-L-arginine methyl ester decreased renal blood flow (301 ± 30 to 228 ± 26 mL/min) and creatinine clearance (40.0 ± 5.8 to 31.1 ± 2.8 mL/min), whereas plasma creatinine increased, but fractional excretion of sodium was unchanged. In sheep with nonhypotensive hyperdynamic sepsis, plasma creatinine increased and there were decreases in creatinine clearance (34.5 ± 4.6 to 20.1 ± 3.7 mL/min) and fractional excretion of sodium despite increased renal blood flow. Infusion of Nω-nitro-L-arginine methyl ester normalized renal blood flow and increased urine output, but creatinine clearance did not improve and plasma creatinine and fractional excretion of sodium increased. In sheep with severe hypotensive sepsis, creatinine clearance decreased further (31.1 ± 5.4 to 16.0 ± 1.7 mL/min) despite increased renal blood flow. Infusion of Nω-nitro-L-arginine methyl ester restored mean arterial pressure and reduced renal blood flow but did not improve plasma creatinine or creatinine clearance. In hyperdynamic sepsis, with or without hypotension, creatinine clearance decreased despite increasing renal blood flow. Intrarenal Nω-nitro-L-arginine methyl ester infusion reduced renal blood flow but did not improve creatinine clearance. These data indicate that septic acute kidney

  11. A dynamic model of renal blood flow autoregulation

    DEFF Research Database (Denmark)

    Holstein-Rathlou, N H; Marsh, D J

    1994-01-01

    To test whether a mathematical model combining dynamic models of the tubuloglomerular feedback (TGF) mechanism and the myogenic mechanism was sufficient to explain dynamic autoregulation of renal blood flow, we compared model simulations with experimental data. To assess the dynamic characteristics...... of renal autoregulation, a broad band perturbation of the arterial pressure was employed in both the simulations and the experiments. Renal blood flow and tubular pressure were used as response variables in the comparison. To better approximate the situation in vivo where a large number of individual...... data, which shows a unimodal curve for the admittance phase. The ability of the model to reproduce the experimental data supports the hypothesis that dynamic autoregulation of renal blood flow is due to the combined action of TGF and the myogenic response....

  12. Cine-CT measurement of cortical renal blood flow

    International Nuclear Information System (INIS)

    Jaschke, W.R.; Gould, R.G.; Cogan, M.G.; Sievers, R.; Lipton, M.J.

    1987-01-01

    A modified indicator-dilution technique using radiographic contrast material and a cine-CT scanner was used to measure blood flow in the renal cortex of dogs. To validate this technique, CT measurements were correlated with simultaneous measurements of flow determined by radioactive microspheres. Measurements were taken during euvolemic conditions and after hemorrhage. Thirty-nine measurements were compared, covering a flow range from 1 to 7 ml min-1 g-1, and a good correlation was found between the cine-CT and microsphere results (r = 0.93; p less than 0.001). Additionally, cine-CT measurements were made of the mean transit time (MTT) of contrast material through the renal cortex, and the reciprocal of these MTT values was also well correlated to microsphere determined flow (r = 0.94; p less than 0.001). Thus, cine-CT appears to be a promising new technique for measuring renal blood flow

  13. Aortic blood flow subtraction: an alternative method for measuring total renal blood flow in conscious dogs

    DEFF Research Database (Denmark)

    Sandgaard, N C F; Andersen, J L; Holstein-Rathlou, N-H

    2002-01-01

    We have measured total renal blood flow (TRBF) as the difference between signals from ultrasound flow probes implanted around the aorta above and below the renal arteries. The repeatability of the method was investigated by repeated, continuous infusions of angiotensin II and endothelin-1 seven...... arterial blood pressure by 49% and decreased TRBF by 12%, providing an increase in renal vascular resistance of 69%. Dynamic analysis showed autoregulation of renal blood flow in the frequency range ... of TRBF by aortic blood flow subtraction is a practical and reliable method that allows direct comparison of excretory function and renal blood flow from two kidneys. The method also allows direct comparison between TRBF and flow in the caudal aorta....

  14. Renal embolic protection devices improve blood flow after stenting for atherosclerotic renal artery stenosis.

    Science.gov (United States)

    Paul, Timir K; Lee, John H; White, Christopher J

    2012-11-15

    We sought to measure angiographic renal frame counts (RFC), as a quantitative angiographic assessment of renal blood flow, to evaluate microvascular compromise due to atheroembolism associated with RAS. Atheroembolism associated with renal artery stenting (RAS) has been implicated as a cause for worsening renal function following successful intervention. Use of a distal embolic protection device (EPD) during RAS has been shown to be safe with debris capture in a high percentage of cases. However, objective benefit for renal function with EPD has been difficult to demonstrate. A control group of 30 consecutive patients (33 kidneys) who underwent RAS without EPD were compared with 33 consecutive patients (33 kidneys) who underwent RAS with EPD using RFC measurement. The prestent and poststent mean RFC for the control group was 30.4 ± 12.1 vs. 23.7 ± 9.9 (P = 0.002) and for the EPD group it was 42.6 ± 12.6 vs. 28.3 ± 9.2 (P renal blood flow, manifested by a greater reduction of the RFC (Δ RFC) 14.2 ± 15.2 vs. 6.7 ± 11.7 (P = 0.03) compared with the control group. The use of an EPD was associated with a much larger improvement in renal blood flow (lower RFC) following RAS. This suggests that EPD's may be effective in preventing renal atheroembolic injury and that a controlled trial measuring the impact of EPD's on renal blood flow following RAS should be performed. Copyright © 2012 Wiley Periodicals, Inc.

  15. Technetium-99m DTPA renal flow studies in Goldblatt hypertension

    International Nuclear Information System (INIS)

    Nally, J.V.; Clarke, H.S.; Windham, J.P.; Grecos, G.P.; Gross, M.L.; Potvin, W.J.

    1985-01-01

    Computer-assisted dynamic renal studies were performed on a group of 14 mongrel dogs before and after the induction of unilateral renal artery stenosis. Ninety-second technetium-99m diethylenetriaminepentaacetic acid ([/sup 99m/Tc]DTPA), 15-min [/sup 99m/Tc]DTPA, and 30-min iodine-131 orthoiodohippurate ([ 131 I]hippuran) time-activity curves were analyzed and correlated with reduction of renal blood flow as measured by electromagnetic flow probe and PAH clearance techniques. For blood flow reductions greater than 33%, the [/sup 99m/Tc]DTPA studies were judged diagnostic of unilateral renal artery stenosis in all cases, whereas the [ 131 I]hippuran time-activity curves were indicative of stenosis in only six of ten studies. Thus, in this model we find the computer-assisted 90-sec [/sup 99m/Tc]DTPA renal flow study to be superior to conventional [ 131 I]hippuran renography in the diagnosis of moderate-to-serve unilateral renal artery stenosis

  16. Role of the renin-angiotensin system in regulation and autoregulation of renal blood flow

    DEFF Research Database (Denmark)

    Sørensen, Charlotte Mehlin; Leyssac, Paul Peter; Skøtt, Ole

    2000-01-01

    The role for ANG II in renal blood flow (RBF) autoregulation is unsettled. The present study was designed to test the effect of clamping plasma ANG II concentrations ([ANG II]) by simultaneous infusion of the angiotensin-converting enzyme inhibitor captopril and ANG II on RBF autoregulation...... in halothane-anesthetized Sprague-Dawley rats. Autoregulation was defined as the RBF response to acute changes in renal perfusion pressure (RPP). Regulation was defined as changes in RBF during long-lasting changes in RPP. The results showed that a prolonged reduction of RPP reset the lower limit...

  17. Tubuloglomerular feedback dynamics and renal blood flow autoregulation in rats

    DEFF Research Database (Denmark)

    Holstein-Rathlou, N H; Wagner, A J; Marsh, D J

    1991-01-01

    To decide whether tubuloglomerular feedback (TGF) can account for renal autoregulation, we tested predictions of a TGF simulation. Broad-band and single-frequency perturbations were applied to arterial pressure; arterial blood pressure, renal blood flow and proximal tubule pressure were measured....... Data were analyzed by linear systems analysis. Broad-band forcings of arterial pressure were also applied to the model to compare experimental results with simulations. With arterial pressure as the input and tubular pressure, renal blood flow, or renal vascular resistance as outputs, the model...... correctly predicted gain and phase only in the low-frequency range. Experimental results revealed a second component of vascular control active at 100-150 mHz that was not predicted by the simulation. Forcings at single frequencies showed that the system behaves linearly except in the band of 33-50 m...

  18. Renal function and plasma volume following ultramarathon cycling.

    Science.gov (United States)

    Neumayr, G; Pfister, R; Hoertnagl, H; Mitterbauer, G; Prokop, W; Joannidis, M

    2005-01-01

    In recreational cyclists marathon cycling influences renal function only on a minimal scale. Respective information on extreme ultramarathon cycling in better trained athletes is not available. The objective was to evaluate the renal and haematological effects of ultraendurance cycling in the world's best ultramarathon cyclists. Creatinine (CR), urea, haemoglobin (Hb), haematocrit (Hct) and plasma volume (PV) were investigated in 16 male ultramarathon cyclists during the 1st Race Across the Alps in 2001 (distance: 525 km; cumulative altitude difference: 12,600 m). All renal functional parameters were normal pre-exercise. During the race serum CR, urea and uric acid rose significantly by 33, 97 % and 18 % (p training kilometers. The serum urea/CR ratio rose above 40 in 12 athletes (75 %). Mean fractional sodium excretion and fractional uric acid excretion fell below 0.5 % (p 0.40; p training.

  19. Renal hemodynamics: the influence of the renal artery ostium flow diverter

    Science.gov (United States)

    Rossmann, Jenn Stroud; Albert, Scott; Balaban, Robert

    2013-11-01

    The recently identified renal artery ostium flow diverter may preferentially direct blood flow to the renal arteries, and may also influence flow patterns and recirculation known to be involved in atherogenesis. Three-dimensional computational fluid dynamics (CFD) simulations of steady and pulsatile blood flow are performed to investigate the influence of diverter size and position, and vascular geometry, on the flow patterns and fluid mechanical forces in the neighborhood of the diverter. CFD results show that the flow diverter does affect the blood distribution: depending on the diverter's position, the flow to the renal arteries may be increased or reduced. The results of simulations also show the diverter's effect on the Wall Shear Stress (WSS) distribution, and suggest that the diverter contributes to an atherogenic environment in the abdominal aorta, while being atheroprotective in the renal arteries themselves. These results support previous clinical findings, and suggest directions for further clinical study. The results of this work have direct implications in understanding the physiological significance of the diverter, and its potential role in the pathophysiological development of atherosclerosis.

  20. Renal transplantant blood flow in patients with acute tubular necrosis

    Energy Technology Data Exchange (ETDEWEB)

    Huic, D; Crnkovic, S; Bubic-Filipi, L J; Grosev, D; Dodig, P; Porapat, M; Puretic, Z [Univ. Hospital Rebro, Zagreb (Croatia)

    1997-09-01

    The aim of this study was to investigate the quantity of renal transport blood flow in patients affected by acute tubular necrosis (ATN). During the four years period two hundred and thirty-three studies were performed using {sup 99m}Tc pertechnetate and {sup 131}I - OIH. Renal blood flow was calculated from the first-pass time activity curves generated over the kidney and aorta and expressed as a percentage of cardiac output (RBF/CO). Renal transplant blood flow is clearly diminished in ATN, similar as in acute rejection, and significantly related to the graft function, what means that RBF/CO value could potentially serve as a prognostic factor in the graft function recovery from ATN.

  1. Dependence of renal blood flow on renal artery stenosis measured using CT angiography

    Energy Technology Data Exchange (ETDEWEB)

    Luedemann, Lutz [Charite - Universitaetsmedizin Berlin (Germany). Dept. of Radiotherapy; Nafz, B.; Persson, P. [Charite - Universitaetsmedizin Berlin (Germany). Inst. for Vegetative Physiology; Elsner, F. [Krankenhaus am Urban, Berlin (Germany). Dept. of Anesthesiology; Grosse-Siestrup, C.; Meissler, M. [Charite - Universitaetsmedizin Berlin (Germany). Experimental Animal Unit; Gutberlet, M. [Charite - Universitaetsmedizin Berlin (Germany). Dept. of Diagnostic and Interventional Radiology; Univ. Leipzig/ Leipzig Heart Center (Germany). Dept. of Diagnostic and Interventional Radiology; Lengsfeld, P.; Voth, M. [Bayer-Schering Pharma AG, Berlin (Germany). Global Medical Affairs Diagnostic Imaging

    2011-03-15

    The present study investigates the suitability of computed tomography angiography (CTA) depicting the degree of renal artery stenosis for estimating renal blood flow (RBF) in a kidney. Materials and Methods: We investigated renal artery stenosis assessment by CTA in eight adult female hybrid pigs with an ultrasound probe implanted at the renal vein for RBF measurement. An inflatable metal-free cuff was placed around the renal artery to control the RBF. The RBF was then reduced in four steps. For each reduced RBF value and baseline RBF, CTA with a reconstructed slice thickness of 0.625 mm was performed in the arterial phase following injection of 80 ml of nonionic intravenous contrast medium. The radius of the stenotic and non-stenotic renal artery segment was measured in the reconstructed images. Results: A significant linear correlation (p < 0.0001) was found between the relative apparent stenosis (calculated as the ratio of the radii of the actual stenotic segment and a non-stenotic renal artery segment) and RBF. The linear regression yielded a slope of 0.57 and a y-axis of 24.1 %. A significant linear correlation (p < 0.0001) was also found between the relative true stenosis (the ratio of the radii of the actual stenotic segment and a non-stenotic renal artery segment at baseline) and the RBF. The linear regression yielded a slope of 0.67 and a y-axis of 13.8 %. Conclusion: The results show that the relative stenosis apparent on CTA differs from the true degree of renal artery stenosis. Nevertheless, the degree of renal artery stenosis determined by CTA provides a reliable estimate of the resulting RBF reduction. (orig.)

  2. Dependence of renal blood flow on renal artery stenosis measured using CT angiography

    International Nuclear Information System (INIS)

    Luedemann, Lutz; Nafz, B.; Persson, P.; Elsner, F.; Grosse-Siestrup, C.; Meissler, M.; Gutberlet, M.; Univ. Leipzig/ Leipzig Heart Center; Lengsfeld, P.; Voth, M.

    2011-01-01

    The present study investigates the suitability of computed tomography angiography (CTA) depicting the degree of renal artery stenosis for estimating renal blood flow (RBF) in a kidney. Materials and Methods: We investigated renal artery stenosis assessment by CTA in eight adult female hybrid pigs with an ultrasound probe implanted at the renal vein for RBF measurement. An inflatable metal-free cuff was placed around the renal artery to control the RBF. The RBF was then reduced in four steps. For each reduced RBF value and baseline RBF, CTA with a reconstructed slice thickness of 0.625 mm was performed in the arterial phase following injection of 80 ml of nonionic intravenous contrast medium. The radius of the stenotic and non-stenotic renal artery segment was measured in the reconstructed images. Results: A significant linear correlation (p < 0.0001) was found between the relative apparent stenosis (calculated as the ratio of the radii of the actual stenotic segment and a non-stenotic renal artery segment) and RBF. The linear regression yielded a slope of 0.57 and a y-axis of 24.1 %. A significant linear correlation (p < 0.0001) was also found between the relative true stenosis (the ratio of the radii of the actual stenotic segment and a non-stenotic renal artery segment at baseline) and the RBF. The linear regression yielded a slope of 0.67 and a y-axis of 13.8 %. Conclusion: The results show that the relative stenosis apparent on CTA differs from the true degree of renal artery stenosis. Nevertheless, the degree of renal artery stenosis determined by CTA provides a reliable estimate of the resulting RBF reduction. (orig.)

  3. 51Cr-EDTA plasma clearance in severe renal failure determined by one plasma sample

    DEFF Research Database (Denmark)

    Kamper, A L; Nielsen, S L

    1989-01-01

    Two hundred and thirty-four measurements of standard 51Cr-EDTA plasma clearance were made in 50 patients with severe chronic renal failure. Based on these data two calculation methods were attempted using one plasma sample drawn 24 h after injection of 51Cr-EDTA. One of the methods used the 'one...... at zero-time was derived from injected dose and body surface area. This method might provide values 1.5 ml/min below or 0.8 ml/min above the established method of 51Cr-EDTA plasma clearance, which would be acceptable for clinical purposes. It is concluded that exact plasma clearance of 51Cr-EDTA in severe...... renal dysfunction (estimated clearance values below 21 ml/min) may be determined with adequate precision by one plasma sample drawn at 24 h after injection of the tracer without sampling at 5 h. This appears to be a very practical simplification....

  4. Renal nerves dynamically regulate renal blood flow in conscious, healthy rabbits.

    Science.gov (United States)

    Schiller, Alicia M; Pellegrino, Peter R; Zucker, Irving H

    2016-01-15

    Despite significant clinical interest in renal denervation as a therapy, the role of the renal nerves in the physiological regulation of renal blood flow (RBF) remains debated. We hypothesized that the renal nerves physiologically regulate beat-to-beat RBF variability (RBFV). This was tested in chronically instrumented, healthy rabbits that underwent either bilateral surgical renal denervation (DDNx) or a sham denervation procedure (INV). Artifact-free segments of RBF and arterial pressure (AP) from calmly resting, conscious rabbits were used to extract RBFV and AP variability for time-domain, frequency-domain, and nonlinear analysis. Whereas steady-state measures of RBF, AP, and heart rate did not statistically differ between groups, DDNx rabbits had greater RBFV than INV rabbits. AP-RBF transfer function analysis showed greater admittance gain in DDNx rabbits than in INV rabbits, particularly in the low-frequency (LF) range where systemic sympathetic vasomotion gives rise to AP oscillations. In the LF range, INV rabbits exhibited a negative AP-RBF phase shift and low coherence, consistent with the presence of an active control system. Neither of these features were present in the LF range of DDNx rabbits, which showed no phase shift and high coherence, consistent with a passive, Ohm's law pressure-flow relationship. Renal denervation did not significantly affect nonlinear RBFV measures of chaos, self-affinity, or complexity, nor did it significantly affect glomerular filtration rate or extracellular fluid volume. Cumulatively, these data suggest that the renal nerves mediate LF renal sympathetic vasomotion, which buffers RBF from LF AP oscillations in conscious, healthy rabbits. Copyright © 2016 the American Physiological Society.

  5. Converting to increased Tc-99m DTPA renal flow from slight decrease in renal flow following angioplastic procedures in a patient with unequal renal artery stenoses

    International Nuclear Information System (INIS)

    Shih Weijen; Mitchell, B.L.

    1990-01-01

    The use of Tc-99m DTPA renal flow imaging has increased in importance since the introduction of catheter angioplasty. The high diagnostic accuracy and non-invasive technique as compared to digital subtraction angiography have done much to enhance its usage in the evaluation of renal functional status. This paper reports Tc-99m DTPA renal flow imaging findings before and after angioplasty in a patient with bilateral renal artery stenosis. The slight decrease in Tc-99m DTPA renal flow on the kidney before angioplasty converted to an increase in flow on the right kidney after angioplasty. Post procedural blood flow was much higher on the right, where stenosis was previously more severe. It is hypothesized that the right kidney was protected from elevated aterial pressure by its 90% arterial stenosis while the left kidney was exposed to elevated systemic blood pressure. Because of vascular damage to the unprotected left kidney, post-angioplasty blood flow was less in the left kidney than in the ischemic but protected right kidney. (orig.) [de

  6. Dynamics of renal blood flow autoregulation in rats

    DEFF Research Database (Denmark)

    Holstein-Rathlou, N H; Wagner, A J; Marsh, D J

    1991-01-01

    Two separate components could be resolved in tests of the dynamic autoregulation of renal blood flow. The slow component corresponds to the frequency at which spontaneous proximal tubular pressure oscillations are found, and are most likely due to the operation of the TGF. The high frequency...

  7. Renal blood flow and oxygenation drive nephron progenitor differentiation.

    Science.gov (United States)

    Rymer, Christopher; Paredes, Jose; Halt, Kimmo; Schaefer, Caitlin; Wiersch, John; Zhang, Guangfeng; Potoka, Douglas; Vainio, Seppo; Gittes, George K; Bates, Carlton M; Sims-Lucas, Sunder

    2014-08-01

    During kidney development, the vasculature develops via both angiogenesis (branching from major vessels) and vasculogenesis (de novo vessel formation). The formation and perfusion of renal blood vessels are vastly understudied. In the present study, we investigated the regulatory role of renal blood flow and O2 concentration on nephron progenitor differentiation during ontogeny. To elucidate the presence of blood flow, ultrasound-guided intracardiac microinjection was performed, and FITC-tagged tomato lectin was perfused through the embryo. Kidneys were costained for the vasculature, ureteric epithelium, nephron progenitors, and nephron structures. We also analyzed nephron differentiation in normoxia compared with hypoxia. At embryonic day 13.5 (E13.5), the major vascular branches were perfused; however, smaller-caliber peripheral vessels remained unperfused. By E15.5, peripheral vessels started to be perfused as well as glomeruli. While the interior kidney vessels were perfused, the peripheral vessels (nephrogenic zone) remained unperfused. Directly adjacent and internal to the nephrogenic zone, we found differentiated nephron structures surrounded and infiltrated by perfused vessels. Furthermore, we determined that at low O2 concentration, little nephron progenitor differentiation was observed; at higher O2 concentrations, more differentiation of the nephron progenitors was induced. The formation of the developing renal vessels occurs before the onset of blood flow. Furthermore, renal blood flow and oxygenation are critical for nephron progenitor differentiation. Copyright © 2014 the American Physiological Society.

  8. Association of plasma manganese levels with chronic renal failure.

    Science.gov (United States)

    Sánchez-González, Cristina; López-Chaves, Carlos; Gómez-Aracena, Jorge; Galindo, Pilar; Aranda, Pilar; Llopis, Juan

    2015-01-01

    Manganese (Mn) is an essential trace element involved in the formation of bone and in amino acid, lipid and carbohydrate metabolism. Mn excess may be neurotoxic to humans, affecting specific areas of the central nervous system. However, relatively little is known about its physiological and/or toxicological effects, and very few data are available concerning the role of Mn in chronic renal failure (CRF). This paper describes a 12-month study of the evolution of plasma Mn levels in predialysis patients with CRF and the relationship with energy and macronutrient intake. The participants in this trial were 64 patients with CRF in predialysis and 62 healthy controls. Plasma levels of creatinine, urea, uric acid, total protein and Mn were measured. The glomerular filtration rate (GFR) was calculated using the Cockcroft-Gault index. The CRF patients had higher plasma levels of creatinine, urea, uric acid and Mn and a lower GFR than the controls. Plasma Mn was positively correlated with creatinine, plasma urea and plasma uric acid and was negatively correlated with the GFR and the intake of energy and macronutrients. In conclusion, CRF in predialysis patients is associated with increases in circulating levels of Mn. Copyright © 2015 Elsevier GmbH. All rights reserved.

  9. Renal blood flow, diuresis and isotope nephrogram in experimental stenosis of the renal artery

    International Nuclear Information System (INIS)

    Pemsel, H.K.; Lange, H.; Mahlstedt, J.; Joseph, K.; Marburg Univ.; Marburg Univ.

    1979-01-01

    After experimental stenosis of the renal artery of the dog, the isotope nephrogram shows a prolongation of the transit-time, when the renal blood flow is reduced to 40-70%. This finding was most significant in low diuresis (0,05-0,2 ml/min), sporadic in moderate diuresis (0,2-2,0 ml/min), no longer demonstrable in forced diuresis (>2,0 ml/min). The diuretic effect of X-ray contrast-medium (70% Na-Meglumin-Jotalamat, 0,5 ml/kg i.v.) normalizes a pathologic ING in low diuresis. (orig.) [de

  10. Plasma EBV microRNAs in paediatric renal transplant recipients.

    Science.gov (United States)

    Hassan, Jaythoon; Dean, Jonathan; De Gascun, Cillian F; Riordan, Michael; Sweeney, Clodagh; Connell, Jeff; Awan, Atif

    2018-06-01

    Epstein-Barr virus (EBV) was the first human virus identified to express microRNA (miRNA). To date, 44 mature miRNAs are encoded for within the EBV genome. EBV miRNAs have not been profiled in paediatric renal transplant recipients. In this study, we investigated circulating EBV miRNA profiles as novel biomarkers in paediatric renal transplant patients. Forty-two microRNAs encoded within 2 EBV open reading frames (BART and BHRF) were examined in renal transplant recipients who resolved EBV infection (REI) or maintained chronic high viral loads (CHL), and in non-transplant patients with acute infectious mononucleosis (IM). Plasma EBV-miR-BART2-5p was present in higher numbers of IM (7/8) and CHL (7/10) compared to REI (7/12) patients. A trend was observed between the numbers of plasma EBV miRNAs expressed and EBV viral load (p < 0.07). Several EBV-miRs including BART7-3p, 15, 9-3p, 11-3p, 1-3p and 3-3p were detected in IM and CHL patients only. The lytic EBV-miRs, BHRF1-2-3p and 1-1, indicating active viral replication, were detected in IM patients only. One CHL patient developed post-transplant lymphoproliferative disease (PTLD) after several years and analysis of 10 samples over a 30-month period showed an average 24-fold higher change in plasma EBV-miR-BART2-5p compared to the CHL group and 110-fold higher change compared to the REI group. Our results suggest that EBV-miR-BART2-5p, which targets the stress-induced immune ligand MICB to escape recognition and elimination by NK cells, may have a role in sustaining high EBV viral loads in CHL paediatric kidney transplant recipients.

  11. Neonatal changes in renal blood flow distribution in puppies

    International Nuclear Information System (INIS)

    Aschinberg, L.C.; Goldsmith, D.I.; Olbing, H.; Spitzer, A.; Edelmann, C.M. Jr.; Blaufox, M.D.

    1975-01-01

    The intrarenal distribution of blood flow was studied in 31 newborn mongrel puppies from 18 h to 70 days using xenon washout and krypton autoradiography. Mean renal blood flow increased from 0.39 +- 0.05 ml/g per min (SE) the 1st wk to 2.06 +- 0.12 ml/g per min at 6 wk. During the 1st wk of life the renal cortex was perfused homogeneously at 0.88 +- 0.19 ml/g min (SE) and accounted for 35 +- 4 percent of the renal blood flow. During the 2nd wk a narrow, rapidly perfused zone of outer cortex was identified which was perfused at 3.35 +- 0.26 ml/g per min, received 19.53 +- 5.05 percent of the total renal blood flow, and represented 15 +- 4 percent of the mass of the total cortex. The inner cortex and outer medulla at this time received 53.40 +- 4.12 percent of the flow at 1.07 +- 0.08 ml/g per min. Outer cortical flow increased with age reaching adult values by about 6 to 10 wk when the rapidly perfused area represented 40 +- 8 percent of the cortex. These changes are parallel to the results of previously reported studies with microspheres in newborn puppies and are compatible with the well-established maturational changes noted in neonates of several species. They represent the first gas-washout studies in animals during the first 6 wk of life

  12. Effect of Equilibrium Flow on Plasma Parameters

    International Nuclear Information System (INIS)

    Mukhopadhyay, S.; Lahiri, S.; Sakanaka, P.H.; Dasgupta, B.

    2003-01-01

    The transition to high confinement modes have been identified with the occurrence of strong shear flow near the plasma boundary. Plasma flow has also been associated with various instabilities, heating and other physical processes. As a result, it has become very important to study the effect of such flows on various plasma parameters. In this paper, we present the numerical solution of plasma equilibrium with incompressible toroidal and poloidal flows in several magnetic confinement configurations including tokamaks. The code, which was reported in the last conference, has been used to solve the problem in both circular and D-shaped devices. A parametric study on the generation of shear flow due to radial electric fields has been carried out. Through this study, it has been possible to generate plasma equilibria having sharp pressure gradients which are remarkably close to those reported in various H-mode experiments. The effects of flow on reverse shear equilibria and on the position of the magnetic axis has been studied. Finally, a detailed study has been carried out to understand the effect of flows on important plasma parameters, such as the poloidal flux function, β, energy confinement time

  13. Effect of hypothermic renal ischaemia on renin secretion rate in man

    DEFF Research Database (Denmark)

    Henriksen, Jens Henrik Sahl; Petersen, H K; Giese, J

    1985-01-01

    Plasma renin concentration (PRC), renal blood flow (RBF) and renin secretion rate (RSR = renal veno-arterial PRC difference multiplied by renal plasma flow) were measured before and after a period of hypothermic renal ischaemia in seven patients undergoing surgery for renal calculi. After...

  14. On plasma flows along vortex lines

    International Nuclear Information System (INIS)

    Bagewadi, C.S.; Prasanna Kumar, K.N.

    1989-01-01

    The plasma flows are discussed and various intrinsic relations along the vortex lines and their principal normals and binormals are obtained. The effects of rotations on Bernoulli surfaces are also studied. (M.K.V.)

  15. Non-equilibrium in flowing atmospheric plasmas

    International Nuclear Information System (INIS)

    Haas, J.C.M. de.

    1986-01-01

    This thesis deals with the fundamental aspects of two different plasmas applied in technological processes. The first one is the cesium seeded argon plasma in a closed cycle Magnetohydrodynamic (MHD) generator, the second is the thermal argon plasma in a cascade arc with an imposed flow. In Chapter 2 the influence of non-equilibrium on the mass and energy balances of a plasma is worked out. The general theory presented there can be applied to both the plasma in an MHD generator and to the cascade arc with imposed flow. Introductions to these plasmas are given in the Chapters 3 and 6 respectively. These chapters are both followed by two chapters which treat the theoretical and the experimental investigations. The results are summarized in Chapter 9. (Auth.)

  16. Decreased cerebral blood flow in renal transplant recipients

    International Nuclear Information System (INIS)

    Kamano, Chisako; Komaba, Yuichi; Sakayori, Osamu; Iino, Yasuhiko; Katayama, Yasuo

    2002-01-01

    We performed single-photon emission computed tomography (SPECT) to investigate the influence of renal transplantation on cerebral blood flow (CBF). Fifteen renal transplant recipients and twelve normal subjects underwent cerebral SPECT with N-isopropyl-p-[ 123 I] iodoamphetamine ( 123 I-IMP). All transplant recipients received prednisolone and cyclosporine (CyA). Regional CBF (rCBF) was measured by defining regions of interest in the cerebral cortex, deep white matter, striatum, thalamus, and cerebellum. In transplant recipients, correlations to the mean overall cortical CBF were assessed using the interval from transplantation to measurement of SPECT, as well as the serum creatinine concentration. Moreover, to investigate the influence of CyA on CBF, the correlation between mean overall cortical CBF and CyA trough concentrations was assessed. In all regions, CBF in renal transplant recipients was significantly lower than in normal subjects. No significant correlation was seen between serum creatinine, interval from transplantation, or CyA trough concentrations and mean overall cortical CBF. Renal transplant recipients demonstrated a decrease in CBF, that can have an associated secondary pathology. Therefore, renal transplant recipients may benefit from post-operative MRI or CT. (author)

  17. Renal blood flow and metabolism after cold ischaemia: peroperative measurements in patients with calculi

    DEFF Research Database (Denmark)

    Petersen, H K; Henriksen, Jens Henrik Sahl

    1984-01-01

    Peroperative measurements of renal blood flow (RBF), renal O2-uptake, and renal venous lactate/pyruvate (L/P) ratio were performed before and after a period of 30-71 min of hypothermic (10-15 degrees C) renal ischaemia in nine patients, undergoing surgery for renal calculi. Before ischaemia, RBF.......01) immediately after re-established perfusion and 36% (P less than 0.02) 30 min later. In one additional patient, who had a short warm ischaemia (8 min), the flow pattern was the same. As arterial pressure remained constant, the reduced RBF signifies an increased renal vascular resistance. Renal O2-uptake...... and renal venous L/P ratio were almost constant, indicating no significant anaerobic processes being involved in the flow response. None of the patients showed any signs of reactive hyperaemia. It is concluded that hypothermic renal ischaemia may be followed by an increased renal vascular resistance even...

  18. Effect of selective inhibition of renal inducible nitric oxide synthase on renal blood flow and function in experimental hyperdynamic sepsis.

    Science.gov (United States)

    Ishikawa, Ken; Calzavacca, Paolo; Bellomo, Rinaldo; Bailey, Michael; May, Clive N

    2012-08-01

    Nitric oxide plays an important role in the control of renal blood flow and renal function. In sepsis, increased levels of inducible nitric oxide synthase produce excessive nitric oxide, which may contribute to the development of acute kidney injury. We, therefore, examined the effects of intrarenal infusion of selective inducible nitric oxide synthase inhibitors in a large animal model of hyperdynamic sepsis in which acute kidney injury occurs in the presence of increased renal blood flow. Prospective crossover randomized controlled interventional studies. University-affiliated research institute. Twelve unilaterally nephrectomized Merino ewes. Infusion of a selective (1400W) and a partially selective inducible nitric oxide synthase inhibitor (aminoguanidine) into the renal artery for 2 hrs after the induction of sepsis, and comparison with a nonselective inhibitor (Nω-nitro-L-arginine methyl ester). In sheep with nonhypotensive hyperdynamic sepsis, creatinine clearance halved (32 to 16 mL/min, ratio [95% confidence interval] 0.51 [0.28-0.92]) despite increased renal blood flow (241 to 343 mL/min, difference [95% confidence interval] 102 [78-126]). Infusion of 1400W did not change renal blood flow, urine output, or creatinine clearance, whereas infusion of Nω-nitro-L-arginine methyl ester and a high dose of aminoguanidine normalized renal blood flow, but did not alter creatinine clearance. In hyperdynamic sepsis, intrarenal infusion of a highly selective inducible nitric oxide synthase inhibitor did not reduce the elevated renal blood flow or improve renal function. In contrast, renal blood flow was reduced by infusion of a nonselective NOS inhibitor or a high dose of a partially selective inducible nitric oxide synthase inhibitor. The renal vasodilatation in septic acute kidney injury may be due to nitric oxide derived from the endothelial and neural isoforms of nitric oxide synthase, but their blockade did not restore renal function.

  19. Asymmetry of renal blood flow in patients with moderate to severe hypertension

    NARCIS (Netherlands)

    van Onna, Marieke; Houben, Alphons J. H. M.; Kroon, Abraham A.; Wierema, Thomas K. A.; Koster, Derk; van Engelshoven, Jos M. A.; de Leeuw, Peter W.

    2003-01-01

    It is generally assumed that renal blood flow is symmetric in the absence of renal artery stenosis. The aim of the present study was to evaluate whether this is really the case. From a group of consecutive hypertensive patients who had undergone renal angiography, we selected those with patent renal

  20. Ultrasonic Doppler measurement of renal artery blood flow

    Science.gov (United States)

    Freund, W. R.; Meindl, J. D.

    1975-01-01

    An extensive evaluation of the practical and theoretical limitations encountered in the use of totally implantable CW Doppler flowmeters is provided. Theoretical analyses, computer models, in-vitro and in-vivo calibration studies describe the sources and magnitudes of potential errors in the measurement of blood flow through the renal artery, as well as larger vessels in the circulatory system. The evaluation of new flowmeter/transducer systems and their use in physiological investigations is reported.

  1. Dynamic modeling of renal blood flow in Dahl hypertensive and normotensive rats

    DEFF Research Database (Denmark)

    Knudsen, Torben; Elmer, Henrik; Knudsen, Morten H

    2004-01-01

    A method is proposed in this paper which allows characterization of renal autoregulatory dynamics and efficiency using quantitative mathematical methods. Based on data from rat experiments, where arterial blood pressure and renal blood flow are measured, a quantitative model for renal blood flow...

  2. CHARACTERIZATION OF RENAL BLOOD FLOW REGULATION BASED ON WAVELET COEFFICIENTS

    DEFF Research Database (Denmark)

    Pavlov, A.N.; Pavlova, O.N.; Mosekilde, Erik

    2010-01-01

    The purpose of this study is to demonstrate the possibility of revealing new characteristic features of renal blood flow autoregulation in healthy and pathological states through the application of discrete wavelet transforms to experimental time series for normotensive and hypertensive rats....... A reduction in the variability of the wavelet coefficients in hypertension is observed at both the microscopic level of the blood flow in efferent arterioles of individual nephrons and at the macroscopic level of the blood pressure in the main arteries. The reduction is manifest in both of the main frequency...

  3. The feasibility of measuring renal blood flow using transesophageal echocardiography in patients undergoing cardiac surgery.

    Science.gov (United States)

    Yang, Ping-Liang; Wong, David T; Dai, Shuang-Bo; Song, Hai-Bo; Ye, Ling; Liu, Jin; Liu, Bin

    2009-05-01

    There is no reliable method to monitor renal blood flow intraoperatively. In this study, we evaluated the feasibility and reproducibility of left renal blood flow measurements using transesophageal echocardiography during cardiac surgery. In this prospective noninterventional study, left renal blood flow was measured with transesophageal echocardiography during three time points (pre-, intra-, and postcardiopulmonary bypass) in 60 patients undergoing cardiac surgery. Sonograms from 6 subjects were interpreted by 2 blinded independent assessors at the time of acquisition and 6 mo later. Interobserver and intraobserver reproducibility were quantified by calculating variability and intraclass correlation coefficients. Patients with Doppler angles of >30 degrees (20 of 60 subjects) were eliminated from renal blood flow measurements. Left renal blood flow was successfully measured and analyzed in 36 of 60 (60%) subjects. Both interobserver and intraobserver variability were renal blood flow measurements were good to excellent (intraclass correlation coefficients 0.604-0.999). Left renal arterial luminal diameter for the pre, intra, and postcardiopulmonary bypass phases, ranged from 3.8 to 4.1 mm, renal arterial velocity from 25 to 35 cm/s, and left renal blood flow from 192 to 299 mL/min. In patients undergoing cardiac surgery, it was feasible in 60% of the subjects to measure left renal blood flow using intraoperative transesophageal echocardiography. The interobserver and intraobserver reproducibility of renal blood flow measurements was good to excellent.

  4. 2. Basis of measurement of plasma flow. 2.3 Plasma flow measurements. Spectroscopic methods

    International Nuclear Information System (INIS)

    Kado, Shinichiro

    2007-01-01

    The construction of optical system, optical fiber incident system, reciprocal linear dispersion, grating smile and astigmatism of the reflection plane diffraction grating spectrometer are explained in order to measure the plasma flow. The specification of flow measurement and evaluation of 0 point of velocity are stated. For examples of measurements, the fine structures of He II (Δn = 3 - 4) in material and plasma(MAP)-II of Tokyo University, plasma flow measurement by the charge exchange recombination spectroscopy using Large Helical Device and by Zeeman spectroscopy using TRIAM-1M tokamak plasma are stated. (S.Y.)

  5. Arterial spin labeling blood flow magnetic resonance imaging for evaluation of renal injury.

    Science.gov (United States)

    Liu, Yupin P; Song, Rui; Liang, Chang hong; Chen, Xin; Liu, Bo

    2012-08-15

    A multitude of evidence suggests that iodinated contrast material causes nephrotoxicity; however, there have been no previous studies that use arterial spin labeling (ASL) blood flow functional magnetic resonance imaging (fMRI) to investigate the alterations in effective renal plasma flow between normointensive and hypertensive rats following injection of contrast media. We hypothesized that FAIR-SSFSE arterial spin labeling MRI may enable noninvasive and quantitative assessment of regional renal blood flow abnormalities and correlate with disease severity as assessed by histological methods. Renal blood flow (RBF) values of the cortex and medulla of rat kidneys were obtained from ASL images postprocessed at ADW4.3 workstation 0.3, 24, 48, and 72 h before and after injection of iodinated contrast media (6 ml/kg). The H&E method for morphometric measurements was used to confirm the MRI findings. The RBF values of the outer medulla were lower than those of the cortex and the inner medulla as reported previously. Iodinated contrast media treatment resulted in decreases in RBF in the outer medulla and cortex in spontaneously hypertensive rats (SHR), but only in the outer medulla in normotensive rats. The iodinated contrast agent significantly decreased the RBF value in the outer medulla and the cortex in SHR compared with normotensive rats after injection of the iodinated contrast media. Histological observations of kidney morphology were also consistent with ASL perfusion changes. These results demonstrate that the RBF value can reflect changes of renal perfusion in the cortex and medulla. ASL-MRI is a feasible and accurate method for evaluating nephrotoxic drugs-induced kidney damage.

  6. Mannitol increases renal blood flow and maintains filtration fraction and oxygenation in postoperative acute kidney injury: a prospective interventional study.

    Science.gov (United States)

    Bragadottir, Gudrun; Redfors, Bengt; Ricksten, Sven-Erik

    2012-08-17

    Acute kidney injury (AKI), which is a major complication after cardiovascular surgery, is associated with significant morbidity and mortality. Diuretic agents are frequently used to improve urine output and to facilitate fluid management in these patients. Mannitol, an osmotic diuretic, is used in the perioperative setting in the belief that it exerts reno-protective properties. In a recent study on uncomplicated postcardiac-surgery patients with normal renal function, mannitol increased glomerular filtration rate (GFR), possibly by a deswelling effect on tubular cells. Furthermore, experimental studies have previously shown that renal ischemia causes an endothelial cell injury and dysfunction followed by endothelial cell edema. We studied the effects of mannitol on renal blood flow (RBF), glomerular filtration rate (GFR), renal oxygen consumption (RVO2), and extraction (RO2Ex) in early, ischemic AKI after cardiac surgery. Eleven patients with AKI were studied during propofol sedation and mechanical ventilation 2 to 6 days after complicated cardiac surgery. All patients had severe heart failure treated with one (100%) or two (73%) inotropic agents and intraaortic balloon pump (36%). Systemic hemodynamics were measured with a pulmonary artery catheter. RBF and renal filtration fraction (FF) were measured by the renal vein thermo-dilution technique and by renal extraction of chromium-51-ethylenediaminetetraacetic acid (51Cr-EDTA), respectively. GFR was calculated as the product of FF and renal plasma flow RBF × (1-hematocrit). RVO2 and RO2Ex were calculated from arterial and renal vein blood samples according to standard formulae. After control measurements, a bolus dose of mannitol, 225 mg/kg, was given, followed by an infusion at a rate of 75 mg/kg/h for two 30-minute periods. Mannitol did not affect cardiac index or cardiac filling pressures. Mannitol increased urine flow by 61% (P renal vascular resistance (P renal FF. Mannitol treatment of postoperative AKI

  7. Flow morphing by coaxial type plasma actuator

    Science.gov (United States)

    Toyoizumi, S.; Aono, H.; Ishikawa, H.

    2017-04-01

    The purpose of study is to achieve the fluid drag reduction of a circular disk by Dielectric Barrier Discharge Plasma Actuator (DBD-PA). We here introduced “Flow Morphing” concept that flow around the body was changed by DBD-PA jet, such as the body shape morphing. Coaxial type DBD-PA injected axisymmetric jet, generating the vortex region on the pressure side of the circular disk. The vortex generated by axisymmetric plasma jet and flow around circular disk were visualized by tracer particles method. The fluid drag was measured by compression type load cell. In addition streamwise velocity was measured by an X-type hot wire probe. The extent of fluid drag reduction by coaxial type DBD-PA jet was influenced by the volume of vortex region and the diameter of plasma electrode.

  8. Renal blood flow using arterial spin labelling MRI and calculated filtration fraction in healthy adult kidney donors Pre-nephrectomy and post-nephrectomy.

    Science.gov (United States)

    Cutajar, Marica; Hilton, Rachel; Olsburgh, Jonathon; Marks, Stephen D; Thomas, David L; Banks, Tina; Clark, Christopher A; Gordon, Isky

    2015-08-01

    Renal plasma flow (RPF) (derived from renal blood flow, RBF) and glomerular filtration rate (GFR) allow the determination of the filtration fraction (FF), which may have a role as a non-invasive renal biomarker. This is a hypothesis-generating pilot study assessing the effect of nephrectomy on renal function in healthy kidney donors. Eight living kidney donors underwent arterial spin labelling (ASL) magnetic resonance imaging (MRI) and GFR measurement prior to and 1 year after nephrectomy. Chromium-51 labelled ethylenediamine tetraacetic acid ((51)Cr-EDTA) with multi-blood sampling was undertaken and GFR calculated. The RBF and GFR obtained were used to calculate FF. All donors showed an increase in single kidney GFR of 24 - 75 %, and all but two showed an increase in FF (-7 to +52 %) after nephrectomy. The increase in RBF, and hence RPF, post-nephrectomy was not as great as the increase in GFR in seven out of eight donors. As with any pilot study, the small number of donors and their relatively narrow age range are potential limiting factors. The ability to measure RBF, and hence RPF, non-invasively, coupled with GFR measurement, allows calculation of FF, a biomarker that might provide a sensitive indicator of loss of renal reserve in potential donors. • Non-invasive MRI measured renal blood flow and calculated renal plasma flow. • Effect of nephrectomy on blood flow and filtration in donors is presented. • Calculated filtration fraction may be a useful new kidney biomarker.

  9. Flowing dusty plasma experiments: generation of flow and measurement techniques

    Science.gov (United States)

    Jaiswal, S.; Bandyopadhyay, P.; Sen, A.

    2016-12-01

    A variety of experimental techniques for the generation of subsonic/supersonic dust fluid flows and means of measuring such flow velocities are presented. The experiments have been carried out in a \\Pi -shaped dusty plasma experimental device with micron size kaolin/melamine formaldehyde particles embedded in a background of argon plasma created by a direct current glow discharge. A stationary dust cloud is formed over the cathode region by precisely balancing the pumping speed and gas flow rate. A flow of dust particles/fluid is generated by additional gas injection from a single or dual locations or by altering the dust confining potential. The flow velocity is then estimated by three different techniques, namely, by super particle identification code, particle image velocimetry analysis and the excitation of dust acoustic waves. The results obtained from these three different techniques along with their merits and demerits are discussed. An estimation of the neutral drag force responsible for the generation as well as the attenuation of the dust fluid flow is made. These techniques can be usefully employed in laboratory devices to investigate linear and non-linear collective excitations in a flowing dusty plasma.

  10. Plasma flow and transport on the tokamak ISTTOK boundary plasma

    International Nuclear Information System (INIS)

    Figueiredo, H.; Silva, C.; Goncalves, B.; Duarte, P.; Fernandes, H.

    2011-01-01

    The ISTTOK boundary plasma velocity near the outer midplane is measured on the parallel and perpendicular directions in four different configurations by reversing independently the toroidal magnetic field and the plasma current directions. The parallel flow is found to not depend significantly on both the toroidal magnetic field and plasma current directions, being always directed towards the nearest limiter in the scrape-off layer. On the contrary, the perpendicular flow is found to follow the E r x B drift direction. The poloidal velocity has also been derived from the correlation of floating potential signals measured on poloidally separated probes and a good agreement with the value derived with the Gundestrup probe is found. Finally, the dynamical interplay between parallel momentum and turbulent particle flux has been investigated and a clear dynamical coupling between these quantities is found in the region inside the limiter.

  11. Acetazolamide assisted Tc-99m MAG3 renography to assess renal blood flow reserve

    International Nuclear Information System (INIS)

    Horita, Yoshio; Hayashida, Kohei; Fukuchi, Kazuki

    2003-01-01

    The present study examines whether or not baseline and acetazolamide (ACZ) Tc-99m MAG3 renography can assess renal blood flow reserve. Renography proceeded for 50 min after sequential injections of 370 MBq Tc-99m MAG3 for baseline renography and 10 min after a 1,000 mg injection of ACZ for ACZ renography. Effective renal plasma flow of renal cortex (cERPF) in each kidney and the percentage change in cERPF of those parameters (ΔERPF) were obtained before and after the administration of ACZ in 10 subjects without hypertension or diabetes (normal group), in 10 with essential hypertension (hypertensive group) and in 10 who had Type 2 diabetes with hypertension (diabetic group). A placebo test was performed in the 10 without hypertension or diabetes using distilled water instead of ACZ (placebo group). The placebo test performed in the 10 without hypertension or diabetes using distilled water instead of ACZ indicated that the parameter variance between the two types of renogram was below 3.2%. The cERPF of baseline and ACZ Tc-99m MAG3 renography and ΔERPF in the normal, hypertensive and diabetic groups were 89±10 and 110±10 ml/min, 89±14 and 117±22 ml/min, 100±23 and 112±23 ml/min, respectively, and 24.5±13.5%, 26.0±9.7% and 12.3±11.1%, respectively. The difference in the cERPF value was significant in the normal and hypertensive groups whereas this did not change in the diabetic group before or after ACZ administration. We suggested that the ΔERPF determined by baseline and ACZ Tc-99m MAG3 renography is a useful parameter for assessing renal blood flow reserve. (author)

  12. Arterio-venous concentration difference of [51Cr]EDTA after a single injection in man. Significance of renal function and local blood flow

    DEFF Research Database (Denmark)

    Rehling, M; Hyldstrup, L; Henriksen, Jens Henrik Sahl

    1989-01-01

    , whereas the difference was very sensitive to even small changes in forearm blood flow within the physiological range. For measurement of renal plasma clearance it is recommended to use one long period: from the time of injection until 300 min p.i. or longer. If the clearance period is too short, the use...... introduced in the measurement of renal plasma clearance and total plasma clearance by using venous blood samples instead of arterial. In 13 patients with GFR ranging from 29 to 150 ml min-1, Ca was higher than Cv immediately after the injection. After mean 38 min (range 12-82 min) the two curves crossed...... of venous samples will overestimate the true renal clearance. Plasma clearance determined by venous and arterial blood samples does not differ significantly as long as the concentration is followed from the time of injection and a long period is applied. When simplified plasma clearance techniques are used...

  13. Comparison of two-dimensional MR angiography and microsphere measurement of renal blood flow for detection of renal artery stenosis

    International Nuclear Information System (INIS)

    Powers, T.A.; Lorenz, C.H.; Shetty, A.N.; Holburn, G.E.; Price, R.R.

    1990-01-01

    This paper compares depiction of the renal arteries by MR angiography to renal blood flow as determined with microspheres in a dog model of renal artery stenosis. A left renal artery stenosis was created by placement of a silk ligature. Nb-95-labeled microspheres were injected into the left ventricle and a reference blood sample was drawn. The dog was imaged in the 1.5-T MR imager with two-dimensional MR angiography sequences. The kidneys were excised, weighted, divided into sections, and counted. Two dogs were studied to date. In dog 1, left renal blood flow (RBF) was 42 mL/min/100 g and right RBF was 337 mL/min/100 g. In dog 2 left RBF was 44 mL/min/100 g and right RBF was 608 mL/min/100 g

  14. Plasma Exchange for Renal Vasculitis and Idiopathic Rapidly Progressive Glomerulonephritis: A Meta-analysis

    DEFF Research Database (Denmark)

    Walsh, Michael; Catapano, Fausta; Szpirt, Wladimir

    2010-01-01

    exchange did not differ significantly across the range of baseline serum creatinine values (P = 0.7) or number of plasma exchange treatments (P = 0.8). The RR for end-stage renal disease was 0.64 (95% CI, 0.47-0.88; P = 0.006), whereas the RR for death alone was 1.01 (95% CI, 0.71-1.4; P = 0......BACKGROUND:: Plasma exchange may be effective adjunctive treatment for renal vasculitis. We performed a systematic review and meta-analysis of randomized controlled trials of plasma exchange for renal vasculitis. STUDY DESIGN:: Systematic review and meta-analysis of articles identified from...

  15. Monoexponential analysis of plasma disappearance of 99mTc-DTPA and 131I-iodohippurate: A reliable method for measuring changes of renal function

    International Nuclear Information System (INIS)

    Clifton, G.G.; Anderson, C.; McMahon, G.; Vargas, R.; Wallin, J.D.

    1989-01-01

    Glomerular filtration rate and effective renal plasma flow were measured in 170 subjects using monoexponential analysis of plasma disappearance curves for 99m Tc-DTPA and 131 I-iodohippurate after single injection. In the current study population, glomerular filtration rate and effective renal plasma flow decreased with increasing age, were less in females than in males, and were less in hypertensives than in normotensives. Differences in glomerular filtration rate according to age and sex in the current study were similar to those reported using traditional creatinine clearance methodology. Monoexponential treatment of plasma isotope disappearance gave reproducible values for both glomerular filtration rate and effective renal plasma flow when measured either during the day or on a daily basis. Intraindividual coefficient of variation was less than 10% for both 99m Tc-DTPA and 131 I-iodohippurate clearances derived from monoexponential analysis. These results demonstrate that monoexponential analysis of plasma disappearance curves for 99m Tc-DTPA and 131 I-iodohippurate after a single injection is a useful method for evaluating changes in renal hemodynamics either during chronic drug therapy or acutely after single dose administration

  16. Diagnostic methods of thermal dusty plasma flows

    International Nuclear Information System (INIS)

    Nefedov, A.P.

    1995-01-01

    The presence in the high-temperature flows of condensed disperse phase (CDP) particles may lead either to an increase of the electron number density n e if the particles assume a positive charge or to its decrease if the charge is negative. The existence of CDP also may effect on optical parameters of the thermal dusty plasma flows, on heat and radiative transfer in the plasma. The entire range of states, from a Debye plasma to a highly nonideal system of charged particles, is realized in a thermal dusty plasma under standard conditions T=2000-3000 K, n e =10 8 - 10 14 cm -3 . The advanced probe and optical diagnostic instruments are needed to study the optical and electrophysical properties of thermal dusty plasma flows. The diagnostic techniques must give the data about such parameters of gas and dispersed phase as temperatures of gas and particles, number densities of electrons, atoms and ions of alkali metals, sizes, velocities and concentrations of CDP particles. It should be noted that number density of alkali metal atoms and gas temperature may be measured by the well known full absorption and generalized reversal methods. This paper describes the probe and optical techniques for diagnostic of dusty plasma flows developed in High Energy Density Research Center of Russian Academy of Sciences. The Forward Angle Scattering Transmissometer (FAST) allows measurement of the average size (Sauter diameter), mass number density, and refractive index of particles in the 0.5-15.0 gm size range. The basis of the method is a dependence of the measured extinction of radiation upon an angular acceptance aperture of the photo detector. The FAST instrument allows one to determine the mass density and the Sauter diameter of a polydispersion of particles without a priori specification of the particle size distribution model and exact data about the article refractive index

  17. Diagnostic methods of thermal dusty plasma flows

    International Nuclear Information System (INIS)

    Nefedov, A.P.

    1995-01-01

    The presence in the high-temperature flows of condensed disperse phase (CDP) particles may lead either to an increase of the electron number density n e if the particles assume a positive charge or to its decrease if the charge is negative. The existence of CDP also may effect on optical parameters of the thermal dusty plasma flows, on heat and radiative transfer in the plasma. The entire range of states, from a Debye plasma to a highly nonideal system of charged particles, is realized in a thermal dusty plasma under standard conditions T=2000-3000 K, n e =10 8 -10 14 cm -3 . The advanced probe and optical diagnostic instruments are needed to study the optical and electrophysical properties of thermal dusty plasma flows. The diagnostic techniques must give the data about such parameters of gas and dispersed phase as temperatures of gas and particles, number densities of electrons, atoms and ions of alkali metals, sizes, velocities and concentrations of CDP particles. It should be noted that number density of alkali metal atoms and gas temperature may be measured by the well known full absorption and generalized reversal methods. This paper describes the probe and optical techniques for diagnostic of dusty plasma flows developed in High Energy Density Research Center of Russian Academy of Sciences. The Forward Angle Scattering Transmissometer (FAST) allows measurement of the average size (Sauter diameter), mass number density, and refractive index of particles in the 0.5-15.0 μm size range. The basis of the method is a dependence of the measured extinction of radiation upon an angular acceptance aperture of the photo detector. The FAST instrument allows one to determine the mass density and the Sauter diameter of a polydispersion of particles without a priori specification of the particle size distribution model and exact data about the particle refractive index

  18. Analysis of renal blood flow and renal volume in normal fetuses and in fetuses with a solitary functioning kidney.

    Science.gov (United States)

    Hindryckx, An; Raaijmakers, Anke; Levtchenko, Elena; Allegaert, Karel; De Catte, Luc

    2017-12-01

    To evaluate renal blood flow and renal volume for the prediction of postnatal renal function in fetuses with solitary functioning kidney (SFK). Seventy-four SFK fetuses (unilateral renal agenesis [12], multicystic dysplastic kidney [36], and severe renal dysplasia [26]) were compared with 58 healthy fetuses. Peak systolic velocity (PSV), pulsatility index (PI), and resistance index (RI) of the renal artery (RA) were measured; 2D and 3D (VOCAL) volumes were calculated. Renal length and glomerular filtration rate (GFR) were obtained in SFK children (2 years). Compared with the control group, the PSV RA was significantly lower in nonfunctioning kidneys and significantly higher in SFK. Volume measurements indicated a significantly larger volume of SFK compared with healthy kidneys. All but 4 children had GFR above 70 mL/min/1.73 m 2 , and compensatory hypertrophy was present in 69% at 2 years. PSV RA and SFK volume correlated with postnatal renal hypertrophy. No correlation between prenatal and postnatal SFK volume and GFR at 2 years was demonstrated. Low PSV RA might have a predictive value for diagnosing a nonfunctioning kidney in fetuses with a SFK. We demonstrated a higher PSV RA and larger renal volume in the SFK compared with healthy kidneys. © 2017 John Wiley & Sons, Ltd.

  19. Functional dilatation and medial remodeling of the renal artery in response to chronic increased blood flow.

    Science.gov (United States)

    Roan, Jun-Neng; Yeh, Chin-Yi; Chiu, Wen-Cheng; Lee, Chou-Hwei; Chang, Shih-Wei; Jiangshieh, Ya-Fen; Tsai, Yu-Chuan; Lam, Chen-Fuh

    2011-01-01

    Renal blood flow (RBF) is tightly regulated by several intrinsic pathways in maintaining optimal kidney blood supply. Using a rat model of aortocaval (AC) fistula, we investigated remodeling of the renal artery following prolonged increased blood flow. An AC fistula was created in the infrarenal aorta of anesthetized rats, and changes of blood flow in the renal artery were assessed using an ultrasonic flow probe. Morphological changes and expression of endothelial nitric oxide synthase and matrix metalloproteinase-2 in the remodeled renal artery were analyzed. Blood flow in the renal artery increased immediately after creation of AC fistula, but normal RBF was restored 8 weeks later. The renal artery dilated significantly 8 weeks after operation. Expression of endothelial nitric oxide synthase and matrix metalloproteinase-2 was upregulated shortly after blood flow increase, and returned to baseline levels after 3 weeks. Histological sections showed luminal dilatation with medial thickening and endothelial cell-to-smooth muscle cell attachments in the remodeled renal artery. Increased RBF was accommodated by functional dilatation and remodeling in the medial layer of the renal artery in order to restore normal blood flow. Our results provide important mechanistic insight into the intrinsic regulation of the renal artery in response to increased RBF. Copyright © 2011 S. Karger AG, Basel.

  20. Renal blood flow regulation and arterial pressure fluctuations: a case study in nonlinear dynamics

    DEFF Research Database (Denmark)

    Holstein-Rathlou, N H; Marsh, D J

    1994-01-01

    in which the kidney is obliged to operate. Were it not for renal blood flow autoregulation, it would be difficult to regulate renal excretory processes so as to maintain whole body variables within narrow bounds. Autoregulation is the noise filter on which other renal processes depend for maintaining...... a relatively noise-free environment in which to work. Because of the time-varying nature of the blood pressure, we have concentrated in this review on the now substantial body of work on the dynamics of renal blood flow regulation and the underlying mechanisms. Renal vascular control mechanisms are not simply....... The significance of deterministic chaos in the context of renal blood flow regulation is that the system regulating blood flow undergoes a physical change to a different dynamical state, and because the change is deterministic, there is every expectation that the critical change will yield itself to experimental...

  1. Renal endothelial function and blood flow predict the individual susceptibility to adriamycin-induced renal damage

    NARCIS (Netherlands)

    Ochodnicky, Peter; Henning, Robert H.; Buikema, Hendrik; Kluppel, Alex C. A.; van Wattum, Marjolein; de Zeeuw, Dick; van Dokkum, Richard P. E.

    2009-01-01

    Susceptibility to renal injury varies among individuals. Previously, we found that individual endothelial function of healthy renal arteries in vitro predicted severity of renal damage after 5/6 nephrectomy. Here we hypothesized that individual differences in endothelial function in vitro and renal

  2. βENaC acts as a mechanosensor in renal vascular smooth muscle cells that contributes to renal myogenic blood flow regulation, protection from renal injury and hypertension.

    Science.gov (United States)

    Drummond, Heather A; Stec, David E

    2015-06-01

    Pressure-induced constriction (also known as the "myogenic response") is an important mechanodependent response in small renal arteries and arterioles. The response is initiated by vascular smooth muscle cell (VSMC) stretch due to an increase in intraluminal pressure and leads to vasoconstriction. The myogenic response has two important roles as a mechanism of local blood flow autoregulation and protection against systemic blood pressure-induced microvascular damage. However, the molecular mechanisms underlying initiation of myogenic response are unresolved. Although several molecules have been considered initiators of the response, our laboratory has focused on the role of degenerin proteins because of their strong evolutionary link to mechanosensing in the nematode. Our laboratory has addressed the hypothesis that certain degenerin proteins act as mechanosensors in VSMCs. This article discusses the importance of a specific degenerin protein, β Epithelial Na + Channel (βENaC), in pressure-induced vasoconstriction, renal blood flow and susceptibility to renal injury. We propose that loss of the renal myogenic constrictor response delays the correction of renal blood flow that occurs with fluctuations in systemic pressure, which allows pressure swings to be transmitted to the microvasculature, thus increasing the susceptibility to renal injury and hypertension. The role of βENaC in myogenic regulation is independent of tubular βENaC and thus represents a non-tubular role for βENaC in renal-cardiovascular homeostasis.

  3. High-NaCl diet impairs dynamic renal blood flow autoregulation in rats with adenine-induced chronic renal failure

    DEFF Research Database (Denmark)

    Saeed, Aso; DiBona, Gerald F; Grimberg, Elisabeth

    2014-01-01

    This study examined the effects of 2 wk of high-NaCl diet on kidney function and dynamic renal blood flow autoregulation (RBFA) in rats with adenine-induced chronic renal failure (ACRF). Male Sprague-Dawley rats received either chow containing adenine or were pair-fed an identical diet without...... arterial pressure variability (SAPV), and heart rate variability were assessed by spectral analytical techniques. Rats with ACRF showed marked reductions in glomerular filtration rate and renal blood flow (RBF), whereas mean arterial pressure and SAPV were significantly elevated. In addition, spontaneous...... adenine (controls). After 10 wk, rats were randomized to either remain on the same diet (0.6% NaCl) or to be switched to high 4% NaCl chow. Two weeks after randomization, renal clearance experiments were performed under isoflurane anesthesia and dynamic RBFA, baroreflex sensitivity (BRS), systolic...

  4. Plasma B-type natriuretic peptide concentration for diagnosis of acute heart failure with renal insufficiency

    Directory of Open Access Journals (Sweden)

    Naila Atik Khan

    2016-07-01

    Full Text Available Background : Plasma B-type natriuretic peptide (BNP is the diagnostic tool for acute heart failure (AHF.This natriu­retic peptide level depends on renal function, through renal metabolism and excretion. Therefore we examined the effect ofrenal impairment on plasma BNP level during diagnosis of AHF.Objective: The objective of the study was to assess the effect of renal dysfunction on plasma BNP level and to determine appropriate cutoff value of plasma BNP to diagnose the patients of AHF with renal insufficiency.Methods: This cross sectional analytical study was conducted in the Depart­ment of Biochemistry Bangabandhu Sheikh Mujib Medical University (BSMMU. The study was done among 90 AHF patients selected from cardiology emergency department during the period of July 2012 to June 2013. After enrollment plasma BNP concentration was measured and eGFR was estimated from serum creatinine by the four parameter Modifica­tion of Diet and Renal Disease (MORD equation and then grouped into two groups on the basis of empirical cut off value of eGFR 60 ml/min/1.73 m2Results: In this study a significant negative correlation was found between plasma BNP evel and eGFR (P<0.001 , with higher BNP levels observed as eGFR declined. The optimal BNP cutoff value for diagno­sis of AHF patients with renal insufficiency was 824 pg/ml. At this cutoff level AHF with renal insufficiency could be diagnosed with sensitivity and specificity of 84% and 71 %, respectively.Conclusions: By adjusting the cutoff value, plasma BNP can be used to diagnose AHF with renal insufficiency with an acceptable sensitivity and specificity.

  5. Extracellular superoxide dismutase is necessary to maintain renal blood flow during sepsis development.

    Science.gov (United States)

    Constantino, Larissa; Galant, Letícia Selinger; Vuolo, Francieli; Guarido, Karla Lorena; Kist, Luiza Wilges; de Oliveira, Giovanna Medeiros Tavares; Pasquali, Matheus Augusto de Bittencourt; de Souza, Cláudio Teodoro; da Silva-Santos, José Eduardo; Bogo, Maurício Reis; Moreira, José Cláudio Fonseca; Ritter, Cristiane; Dal-Pizzol, Felipe

    2017-12-01

    Extracellular superoxide dismutase (ECSOD) protects nitric oxide (NO) bioavailability by decreasing superoxide levels and preventing peroxynitrite generation, which is important in maintaining renal blood flow and in preventing acute kidney injury. However, the profile of ECSOD expression after sepsis is not fully understood. Therefore, we intended to evaluate the content and gene expression of superoxide dismutase (SOD) isoforms in the renal artery and their relation to renal blood flow. Sepsis was induced in Wistar rats by caecal ligation and perforation. Several times after sepsis induction, renal blood flow (12, 24 and 48 h); the renal arterial content of SOD isoforms, nitrotyrosine, endothelial and inducible nitric oxide synthase (e-NOS and i-NOS), and phosphorylated vasodilator-stimulated phosphoprotein (pVASP); and SOD activity (3, 6 and 12 h) were measured. The influence of a SOD inhibitor was also evaluated. An increase in ECSOD content was associated with decreased 3-nitrotyrosine levels. These events were associated with an increase in pVASP content and maintenance of renal blood flow. Moreover, previous treatment with a SOD inhibitor increased nitrotyrosine content and reduced renal blood flow. ECSOD appears to have a major role in decreasing peroxynitrite formation in the renal artery during the early stages of sepsis development, and its application can be important in renal blood flow control and maintenance during septic insult.

  6. Activation of GLP-1 receptors on vascular smooth muscle cells reduces the autoregulatory response in afferent arterioles and increases renal blood flow.

    Science.gov (United States)

    Jensen, Elisa P; Poulsen, Steen S; Kissow, Hannelouise; Holstein-Rathlou, Niels-Henrik; Deacon, Carolyn F; Jensen, Boye L; Holst, Jens J; Sorensen, Charlotte M

    2015-04-15

    Glucagon-like peptide (GLP)-1 has a range of extrapancreatic effects, including renal effects. The mechanisms are poorly understood, but GLP-1 receptors have been identified in the kidney. However, the exact cellular localization of the renal receptors is poorly described. The aim of the present study was to localize renal GLP-1 receptors and describe GLP-1-mediated effects on the renal vasculature. We hypothesized that renal GLP-1 receptors are located in the renal microcirculation and that activation of these affects renal autoregulation and increases renal blood flow. In vivo autoradiography using (125)I-labeled GLP-1, (125)I-labeled exendin-4 (GLP-1 analog), and (125)I-labeled exendin 9-39 (GLP-1 receptor antagonist) was performed in rodents to localize specific GLP-1 receptor binding. GLP-1-mediated effects on blood pressure, renal blood flow (RBF), heart rate, renin secretion, urinary flow rate, and Na(+) and K(+) excretion were investigated in anesthetized rats. Effects of GLP-1 on afferent arterioles were investigated in isolated mouse kidneys. Specific binding of (125)I-labeled GLP-1, (125)I-labeled exendin-4, and (125)I-labeled exendin 9-39 was observed in the renal vasculature, including afferent arterioles. Infusion of GLP-1 increased blood pressure, RBF, and urinary flow rate significantly in rats. Heart rate and plasma renin concentrations were unchanged. Exendin 9-39 inhibited the increase in RBF. In isolated murine kidneys, GLP-1 and exendin-4 significantly reduced the autoregulatory response of afferent arterioles in response to stepwise increases in pressure. We conclude that GLP-1 receptors are located in the renal vasculature, including afferent arterioles. Activation of these receptors reduces the autoregulatory response of afferent arterioles to acute pressure increases and increases RBF in normotensive rats. Copyright © 2015 the American Physiological Society.

  7. Plasma actuators for bluff body flow control

    Science.gov (United States)

    Kozlov, Alexey V.

    The aerodynamic plasma actuators have shown to be efficient flow control devices in various applications. In this study the results of flow control experiments utilizing single dielectric barrier discharge plasma actuators to control flow separation and unsteady vortex shedding from a circular cylinder in cross-flow are reported. This work is motivated by the need to reduce landing gear noise for commercial transport aircraft via an effective streamlining created by the actuators. The experiments are performed at Re D = 20,000...164,000. Circular cylinders in cross-flow are chosen for study since they represent a generic flow geometry that is similar in all essential aspects to a landing gear oleo or strut. The minimization of the unsteady flow separation from the models and associated large-scale wake vorticity by using actuators reduces the radiated aerodynamic noise. Using either steady or unsteady actuation at ReD = 25,000, Karman shedding is totally eliminated, turbulence levels in the wake decrease significantly and near-field sound pressure levels are reduced by 13.3 dB. Unsteady actuation at an excitation frequency of St D = 1 is found to be most effective. The unsteady actuation also has the advantage that total suppression of shedding is achieved for a duty cycle of only 25%. However, since unsteady actuation is associated with an unsteady body force and produces a tone at the actuation frequency, steady actuation is more suitable for noise control applications. Two actuation strategies are used at ReD = 82,000: spanwise and streamwise oriented actuators. Near field microphone measurements in an anechoic wind tunnel and detailed study of the near wake using LDA are presented in the study. Both spanwise and streamwise actuators give nearly the same noise reduction level of 11.2 dB and 14.2 dB, respectively, and similar changes in the wake velocity profiles. The contribution of the actuator induced noise is found to be small compared to the natural shedding

  8. Evaluation of Renal Blood Flow and Oxygenation in CKD Using Magnetic Resonance Imaging.

    Science.gov (United States)

    Khatir, Dinah S; Pedersen, Michael; Jespersen, Bente; Buus, Niels H

    2015-09-01

    Animal studies suggest that progression of chronic kidney disease (CKD) is related to renal hypoxia. With renal blood supply determining oxygen delivery and sodium absorption being the main contributor to oxygen consumption, we describe the relationship between renal oxygenation, renal artery blood flow, and sodium absorption in patients with CKD and healthy controls. Cross-sectional study. 62 stable patients with CKD stages 3 to 4 (mean age, 61±13 [SD] years) and 24 age- and sex-matched controls. CKD versus control status. Renal artery blood flow, tissue oxygenation (relative changes in deoxyhemoglobin concentration of the renal medulla [MR2*] and cortex [CR2*]), and sodium absorption. Renal artery blood flow was determined by phase-contrast magnetic resonance imaging (MRI); MR2* and CR2* were determined by blood oxygen level-dependent MRI. Ultrafiltered and reabsorbed sodium were determined from measured glomerular filtration rate (mGFR) and 24-hour urine collections. mGFR in patients was 37% that of controls (36±15 vs 97±23 mL/min/1.73 m(2); P renal artery blood flow was 72% that of controls (319 vs 443 mL/min; P renal artery blood flow or sodium absorption. Increasing arterial blood oxygen tension by breathing 100% oxygen had very small effects on CR2*, but reduced MR2* in both groups. Only renal artery blood flow was determined and thus regional perfusion could not be related to CR2* or MR2*. In CKD, reductions of mGFR and reabsorbed sodium are more than double that of renal artery blood flow, whereas cortical and medullary oxygenation are within the range of healthy persons. Reduction in glomerular filtration fraction may prevent renal hypoxia in CKD. Copyright © 2015 National Kidney Foundation, Inc. Published by Elsevier Inc. All rights reserved.

  9. Effect of region assignment on relative renal blood flow estimates using radionuclides

    International Nuclear Information System (INIS)

    Harris, C.C.; Ford, K.K.; Coleman, R.E.; Dunnick, N.R.

    1984-01-01

    To determine the value of the initial phase of the Tc-99m DTPA renogram in the direct estimation of relative renal blood flow in dogs, the ratios of the slopes of renal time-activity curves were compared with the ratios of measured blood flow. Radionuclide results were dependent on region-of-interest (ROI) and background ROI assignment, and correlated well with measured relative flow only with a maximum renal outline region. Curve slope ratios correlated well with measured flow ratios with and without background correction, while 1- to 2-minute uptake ratios correlated well only when corrected for background

  10. Experimental Investigation of Hypersonic Flow and Plasma Aerodynamic Actuation Interaction

    International Nuclear Information System (INIS)

    Sun Quan; Cheng Bangqin; Li Yinghong; Cui Wei; Yu Yonggui; Jie Junhun

    2013-01-01

    For hypersonic flow, it was found that the most effective plasma actuator is derived from an electromagnetic perturbation. An experimental study was performed between hypersonic flow and plasma aerodynamic actuation interaction in a hypersonic shock tunnel, in which a Mach number of 7 was reached. The plasma discharging characteristic was acquired in static flows. In a hypersonic flow, the flow field can affect the plasma discharging characteristics. DC discharging without magnetic force is unstable, and the discharge channel cannot be maintained. When there is a magnetic field, the energy consumption of the plasma source is approximately three to four times larger than that without a magnetic field, and at the same time plasma discharge can also affect the hypersonic flow field. Through schlieren pictures and pressure measurement, it was found that plasma discharging could induce shockwaves and change the total pressure and wall pressure of the flow field

  11. Renal sympathetic nerve, blood flow, and epithelial transport responses to thermal stress.

    Science.gov (United States)

    Wilson, Thad E

    2017-05-01

    Thermal stress is a profound sympathetic stress in humans; kidney responses involve altered renal sympathetic nerve activity (RSNA), renal blood flow, and renal epithelial transport. During mild cold stress, RSNA spectral power but not total activity is altered, renal blood flow is maintained or decreased, and epithelial transport is altered consistent with a sympathetic stress coupled with central volume loaded state. Hypothermia decreases RSNA, renal blood flow, and epithelial transport. During mild heat stress, RSNA is increased, renal blood flow is decreased, and epithelial transport is increased consistent with a sympathetic stress coupled with a central volume unloaded state. Hyperthermia extends these directional changes, until heat illness results. Because kidney responses are very difficult to study in humans in vivo, this review describes and qualitatively evaluates an in vivo human skin model of sympathetically regulated epithelial tissue compared to that of the nephron. This model utilizes skin responses to thermal stress, involving 1) increased skin sympathetic nerve activity (SSNA), decreased skin blood flow, and suppressed eccrine epithelial transport during cold stress; and 2) increased SSNA, skin blood flow, and eccrine epithelial transport during heat stress. This model appears to mimic aspects of the renal responses. Investigations of skin responses, which parallel certain renal responses, may aid understanding of epithelial-sympathetic nervous system interactions during cold and heat stress. Copyright © 2016 Elsevier B.V. All rights reserved.

  12. Renal endothelial function and blood flow predict the individual susceptibility to adriamycin-induced renal damage

    NARCIS (Netherlands)

    Ochodnicky, Peter; Henning, Robert H.; Buikema, Hendrik; Kluppel, Alex C. A.; van Wattum, Marjolein; de Zeeuw, Dick; van Dokkum, Richard P. E.

    Background. Susceptibility to renal injury varies among individuals. Previously, we found that individual endothelial function of healthy renal arteries in vitro predicted severity of renal damage after 5/6 nephrectomy. Here we hypothesized that individual differences in endothelial function in

  13. Prognostic value of renal fractional flow reserve in blood pressure response after renal artery stenting (PREFER study).

    Science.gov (United States)

    Kądziela, Jacek; Januszewicz, Andrzej; Prejbisz, Aleksander; Michałowska, Ilona; Januszewicz, Magdalena; Florczak, Elżbieta; Kalińczuk, Łukasz; Norwa-Otto, Bożena; Warchoł, Ewa; Witkowski, Adam

    2013-01-01

    The aim of our study was to determine a potential relationship between resting translesional pressures ratio (Pd/Pa ratio), renal fractional flow reserve (rFFR) and blood pressure response after renal artery stenting. Thirty five hypertensive patients (49% males, mean age 64 years) with at least 60% stenosis in angiography, underwent renal artery stenting. Translesional systolic pressure gradient (TSPG), Pd/Pa ratio (the ratio of mean distal to lesion and mean proximal pressures) and hyperemic rFFR - after intrarenal administration of papaverine - were measured before stent implantation. Ambulatory blood pressure measurements (ABPM) were recorded before the procedure and after 6 months. The ABPM results were presented as blood pressure changes in subgroups of patients with normal (≥ 0.9) vs. abnormal (renal artery stenting. Median changes of 24-h systolic/diastolic blood pressure were comparable in patients with abnormal vs. normal Pd/Pa ratio (-4/-3 vs. 0/2 mm Hg; p = NS) and with abnormal vs. normal rFFR (-2/-1 vs. -2/-0.5 mm Hg, respectively). Physiological assessment of renal artery stenosis using Pd/Pa ratio and papaverine- induced renal fractional fl ow reserve did not predict hypertension response after renal artery stenting.

  14. Sympathetic nervous activity and renal and systemic hemodynamics in cirrhosis: plasma norepinephrine concentration, hepatic extraction, and renal release

    DEFF Research Database (Denmark)

    Ring-Larsen, H; Hesse, B; Henriksen, Jens Henrik Sahl

    1982-01-01

    as previously reported in healthy controls. The right kidney released NE into the systemic circulation. Renal venous plasma NE exceeded arterial concentration by 34% (p less than 0.01). It is concluded that sympathetic nervous activity is enhanced in patients with cirrhosis, and that this hyperactivity may...... in patients than controls (82 vs. 95 mm Hg, p less than 0.05) but did not change during the tilt. Plasma norepinephrine (NE) concentration was significantly higher in another eight patients with cirrhosis than in eight healthy controls (mean: 0.45 vs. 0.21 ng per ml in recumbency, p less than 0.02). Following...

  15. Plasma flow in a pressure pulsed argon cascade arc

    NARCIS (Netherlands)

    de Haas, J.C.M.; Bol, L.; Kroesen, G.M.W.; Timmermans, C.J.; Timmermans, C.J.

    1985-01-01

    Flowing thermal plasmas are frequently used e . g. in welding, cutting, plasma deposition and testing materials at high temperatures . In most of the applications the geometry is complex . In the cascade arc the argon plasma flows through a straight circular channel with a constant area. The study

  16. Cellular transport of l-arginine determines renal medullary blood flow in control rats, but not in diabetic rats despite enhanced cellular uptake capacity.

    Science.gov (United States)

    Persson, Patrik; Fasching, Angelica; Teerlink, Tom; Hansell, Peter; Palm, Fredrik

    2017-02-01

    Diabetes mellitus is associated with decreased nitric oxide bioavailability thereby affecting renal blood flow regulation. Previous reports have demonstrated that cellular uptake of l-arginine is rate limiting for nitric oxide production and that plasma l-arginine concentration is decreased in diabetes. We therefore investigated whether regional renal blood flow regulation is affected by cellular l-arginine uptake in streptozotocin-induced diabetic rats. Rats were anesthetized with thiobutabarbital, and the left kidney was exposed. Total, cortical, and medullary renal blood flow was investigated before and after renal artery infusion of increasing doses of either l-homoarginine to inhibit cellular uptake of l-arginine or N ω -nitro- l-arginine methyl ester (l-NAME) to inhibit nitric oxide synthase. l-Homoarginine infusion did not affect total or cortical blood flow in any of the groups, but caused a dose-dependent reduction in medullary blood flow. l-NAME decreased total, cortical and medullary blood flow in both groups. However, the reductions in medullary blood flow in response to both l-homoarginine and l-NAME were more pronounced in the control groups compared with the diabetic groups. Isolated cortical tubular cells displayed similar l-arginine uptake capacity whereas medullary tubular cells isolated from diabetic rats had increased l-arginine uptake capacity. Diabetics had reduced l-arginine concentrations in plasma and medullary tissue but increased l-arginine concentration in cortical tissue. In conclusion, the reduced l-arginine availability in plasma and medullary tissue in diabetes results in reduced nitric oxide-mediated regulation of renal medullary hemodynamics. Cortical blood flow regulation displays less dependency on extracellular l-arginine and the upregulated cortical tissue l-arginine may protect cortical hemodynamics in diabetes. Copyright © 2017 the American Physiological Society.

  17. Determination of the separate effective renal blood flow by mathematical interpretation of radionephrograms

    International Nuclear Information System (INIS)

    Degtereva, O.A.; Zvonova, I.A.

    1982-01-01

    Mathematical model of nephrotropic compound kinetics was plotted, and using +t, the procedure of determination of separate effective, renal blood flow was developed. This procedure was based on radionephrograms obtained after intravenous injection of 131 I hippuran. Partial renal functions were found according summary gammachronograms of the precardiac and renal areas with double taking of blood samples. The technique of plotting of theoretical summary radionephrogram was solved according to calculated parameters [ru

  18. Changes of renal blood flow after ESWL: assessment by ASL MR imaging, contrast enhanced MR imaging, and renal resistive index.

    Science.gov (United States)

    Abd Ellah, Mohamed; Kremser, Christian; Pallwein, Leo; Aigner, Friedrich; Schocke, Michael; Peschel, Reinhard; Pedross, Florian; Pinggera, Germar-Michael; Wolf, Christian; Alsharkawy, Mostafa A M; Jaschke, Werner; Frauscher, Ferdinand

    2010-10-01

    The annual incidence of stone formation is increased in the industrialised world. Extracorporeal shockwave lithotripsy is a non-invasive effective treatment of upper urinary tract stones. This study is aimed to evaluate changes of renal blood flow in patients undergoing extracorporeal shock wave lithotripsy (ESWL) by arterial spin labeling (ASL) MR imaging, contrast enhanced dynamic MR imaging, and renal resistive index (RI). Thirteen patients with nephrolithiasis were examined using MR imaging and Doppler ultrasound 12h before and 12h after ESWL. ASL sequence was done for both kidneys and followed by contrast enhanced MR imaging. In addition RI Doppler ultrasound measurements were performed. A significant increase in RI (pESWL causes changes in RI and ASL MR imaging, which seem to reflect changes in renal blood flow. Copyright © 2009 Elsevier Ireland Ltd. All rights reserved.

  19. Results and validity of renal blood flow measurements using Xenon 133

    International Nuclear Information System (INIS)

    Serres, P.; Danet, B.; Guiraud, R.; Durand, D.; Ader, J.L.

    1975-01-01

    The renal blood flow was measured by external recording of the xenon 133 excretion curve. The study involved 45 patients with permanent high blood pressure and 7 transplant patients. The validity of the method was checked on 10 dogs. From the results it seems that the cortical blood flow, its fraction and the mean flow rate are the most representative of the renal haemodynamics parameters, from which may be established the repercussions of blood pressure on kidney vascularisation. Experiments are in progress on animals to check the compartment idea by comparing injections into the renal artery and into various kidney tissues in situ [fr

  20. Differences in dynamic autoregulation of renal blood flow between SHR and WKY rats

    DEFF Research Database (Denmark)

    Chen, Y M; Holstein-Rathlou, N H

    1993-01-01

    by chaotic fluctuations. We sought to determine whether this change was associated with a change in the dynamic autoregulation of renal blood flow. In halothane-anesthetized 250- to 320-g SHR and WKY rats, renal blood flow was measured during "white noise" forcing of arterial blood pressure. The frequency...... conclude that the change in the dynamics of TGF leads to a change in the dynamic autoregulation of renal blood flow between SHR and WKY rats. This change results in a more efficient dynamic autoregulation of renal blood flow in the SHR compared with the WKY rats. The functional consequences of this......In halothane-anesthetized Wistar-Kyoto (WKY) rats the single-nephron blood flow and the proximal tubule pressure oscillate at a frequency of 35-50 mHz because of the operation of the tubuloglomerular feedback (TGF) mechanism. In spontaneously hypertensive rats (SHR) the oscillations are replaced...

  1. Renal cortical and medullary blood flow responses to altered NO availability in humans

    DEFF Research Database (Denmark)

    Damkjær, Mads; Vafaee, Manoucher; Møller, Michael L

    2010-01-01

    The objective of this study was to quantify regional renal blood flow in humans. In nine young volunteers on a controlled diet, the lower abdomen was CT-scanned, and regional renal blood flow was determined by positron emission tomography (PET) scanning using H(2)(15)O as tracer. Measurements were......-NMMA injection to 1.57 ± 0.17 ml·g tissue(-1)·min(-1) (P blood flow was 4.67 ± 0.31 ml·g tissue(-1)·min(-1) during control, unchanged by glyceryl nitrate, and decreased after L-NMMA [3.48 ± 0.23 ml·(g·min)(-1), P renal medullary region in which...... the measured blood flow is 1) low, 2) independent of reduction in the VOI, and 3) reactive to changes in systemic NO supply. The technique seems to provide indices of renal medullary blood flow in humans....

  2. Absolute renal blood flow quantification by dynamic MRI and Gd-DTPA

    International Nuclear Information System (INIS)

    Vallee, J.P.; Lazeyras, F.; Khan, H.G.; Terrier, F.

    2000-01-01

    The aim of this study was to demonstrate the feasibility of the absolute renal blood flow quantification using MRI and injection of contrast media. Using a T1-weighted fast gradient sequence following an intravenous bolus injection of Gd-DTPA, dynamic images of the kidney were obtained in patients with well-functioning native kidneys (n=7) or transplant (n=9), with significant renal artery stenosis (n=4) and with renal failure (n=7). After signal intensity calibration, the absolute renal perfusion was equal to the wash-in slope of the renal transit curve divided by the contrast medium concentration at the peak of the bolus in the aorta. The cortical blood flow was 2.54±1.16 ml/min per gram in well-functioning kidneys decreasing to 1.09±0.75 ml/min per gram in case of renal artery stenosis (p=0.04) and to 0.51 ± 0.34 ml/min per gram in case of renal failure (p<0.001). These measurements were in agreement with previous results obtained by other methods. A standard MRI imaging sequence and a simple model can provide realistic quantitative data on renal perfusion. This work justifies further studies to compare this model with a gold standard for renal blood flow measurements. (orig.)

  3. Arterial Transit Time-corrected Renal Blood Flow Measurement with Pulsed Continuous Arterial Spin Labeling MR Imaging.

    Science.gov (United States)

    Shimizu, Kazuhiro; Kosaka, Nobuyuki; Fujiwara, Yasuhiro; Matsuda, Tsuyoshi; Yamamoto, Tatsuya; Tsuchida, Tatsuro; Tsuchiyama, Katsuki; Oyama, Nobuyuki; Kimura, Hirohiko

    2017-01-10

    The importance of arterial transit time (ATT) correction for arterial spin labeling MRI has been well debated in neuroimaging, but it has not been well evaluated in renal imaging. The purpose of this study was to evaluate the feasibility of pulsed continuous arterial spin labeling (pcASL) MRI with multiple post-labeling delay (PLD) acquisition for measuring ATT-corrected renal blood flow (ATC-RBF). A total of 14 volunteers were categorized into younger (n = 8; mean age, 27.0 years) and older groups (n = 6; 64.8 years). Images of pcASL were obtained at three different PLDs (0.5, 1.0, and 1.5 s), and ATC-RBF and ATT were calculated using a single-compartment model. To validate ATC-RBF, a comparative study of effective renal plasma flow (ERPF) measured by 99m Tc-MAG3 scintigraphy was performed. ATC-RBF was corrected by kidney volume (ATC-cRBF) for comparison with ERPF. The younger group showed significantly higher ATC-RBF (157.68 ± 38.37 mL/min/100 g) and shorter ATT (961.33 ± 260.87 ms) than the older group (117.42 ± 24.03 mL/min/100 g and 1227.94 ± 226.51 ms, respectively; P renal ASL-MRI as debated in brain imaging.

  4. Plasma flow in a curved magnetic field

    International Nuclear Information System (INIS)

    Lindberg, L.

    1977-09-01

    A beam of collisionless plasma is injected along a longitudinal magnetic field into a region of curved magnetic field. Two unpredicted phenomena are observed: The beam becomes deflected in the direction opposite to that in which the field is curved, and it contracts to a flat slab in the plane of curvature of the magnetic field. The phenomenon is of a general character and can be expected to occur in a very wide range of densities. The lower density limit is set by the condition for self-polarization, nm sub(i)/epsilon 0 B 2 >> 1 or, which is equivalent, c 2 /v 2 sub(A) >> 1, where c is the velocity of light, and v sup(A) the Alfven velocity. The upper limit is presumably set by the requirement ωsub(e)tau(e) >> 1. The phenomenon is likely to be of importance e.g. for injection of plasma into magnetic bottles and in space and solar physics. The paper illustrates the comlexity of plasma flow phenomena and the importance of close contact between experimental and theoretical work. (author)

  5. Renal perfusion scintiscan

    Science.gov (United States)

    ... Radionuclide renal perfusion scan; Perfusion scintiscan - renal; Scintiscan - renal perfusion Images Kidney anatomy Kidney - blood and urine flow Intravenous pyelogram References Rottenberg G, Andi AC. Renal ...

  6. Renal artery blood flow assessed by video dilution technique before and after percutaneous transluminal angioplasty

    International Nuclear Information System (INIS)

    Lantz, B.M.T.; Link, D.P.; Lewis, E.L.; Foerster, J.M.; Lee, G.

    1981-01-01

    Successful percutaneous transluminal angioplasty was performed in 3 cases of renal artery stenosis where the effect upon renal blood flow was quantified by video dilution technique. This technique adds important information to pressure gradients and renin assays obtained during the dilatation procedure. (Auth.)

  7. Comparison between total and renal plasma clearance of [51Cr]EDTA

    International Nuclear Information System (INIS)

    Broechner-Mortensen, J.; Roedbro, P.

    1976-01-01

    The total plasma (E 1 ) and renal plasma (E 2 ) clearances of [ 51 Cr]EDTA were measured simultaneously in 40 patients with a wide range of renal function. The regression equation was E 1 = 0.997E 2 + 4.1; the slope of the regression line was not significantly different from 1.00, and the intercept differed significantly from zero. The results suggest that [ 51 Cr]EDTA has a significant extrarenal clearance of approximately 4 ml/min, independent of renal function. The data are used to correct the total [ 51 Cr]EDTA plasma clearance, measured by a simplified method, to yield a rapid, accurate and precise measurement of glomerular filtration rate for routine clinical use. (Auth.)

  8. IgG4-related tubulointerstitial nephritis with plasma cell-rich renal arteritis.

    Science.gov (United States)

    Sharma, Shree G; Vlase, Horia L; D'Agati, Vivette D

    2013-04-01

    Immunoglobulin G4 (IgG4)-related tubulointerstitial nephritis is a newly recognized clinicopathologic entity that may occur as an isolated renal lesion or as part of a multisystem disorder. It is characterized by plasma cell-rich interstitial nephritis with abundant IgG4-positive plasma cells and IgG-dominant tubulointerstitial immune deposits. We report the first case of IgG4-related tubulointerstitial nephritis with multifocal plasma cell-rich renal arteritis presenting as acute kidney injury in a 72-year-old man. Seven weeks of prednisone therapy led to nearly complete recovery of kidney function. This case enlarges the morphologic spectrum of this disorder and emphasizes the need to distinguish it from other causes of renal vasculitis. Copyright © 2013 National Kidney Foundation, Inc. Published by Elsevier Inc. All rights reserved.

  9. Aortic Blood Flow Reversal Determines Renal Function: Potential Explanation for Renal Dysfunction Caused by Aortic Stiffening in Hypertension.

    Science.gov (United States)

    Hashimoto, Junichiro; Ito, Sadayoshi

    2015-07-01

    Aortic stiffness determines the glomerular filtration rate (GFR) and predicts the progressive decline of the GFR. However, the underlying pathophysiological mechanism remains obscure. Recent evidence has shown a close link between aortic stiffness and the bidirectional (systolic forward and early diastolic reverse) flow characteristics. We hypothesized that the aortic stiffening-induced renal dysfunction is attributable to altered central flow dynamics. In 222 patients with hypertension, Doppler velocity waveforms were recorded at the proximal descending aorta to calculate the reverse/forward flow ratio. Tonometric waveforms were recorded to measure the carotid-femoral (aortic) and carotid-radial (peripheral) pulse wave velocities, to estimate the aortic pressure from the radial waveforms, and to compute the aortic characteristic impedance. In addition, renal hemodynamics was evaluated by duplex ultrasound. The estimated GFR was inversely correlated with the aortic pulse wave velocity, reverse/forward flow ratio, pulse pressure, and characteristic impedance, whereas it was not correlated with the peripheral pulse wave velocity or mean arterial pressure. The association between aortic pulse wave velocity and estimated GFR was independent of age, diabetes mellitus, hypercholesterolemia, and antihypertensive medication. However, further adjustment for the aortic reverse/forward flow ratio and pulse pressure substantially weakened this association, and instead, the reverse/forward flow ratio emerged as the strongest determinant of estimated GFR (P=0.001). A higher aortic reverse/forward flow ratio was also associated with lower intrarenal forward flow velocities. These results suggest that an increase in aortic flow reversal (ie, retrograde flow from the descending thoracic aorta toward the aortic arch), caused by aortic stiffening and impedance mismatch, reduces antegrade flow into the kidney and thereby deteriorates renal function. © 2015 American Heart Association

  10. High-NaCl diet impairs dynamic renal blood flow autoregulation in rats with adenine-induced chronic renal failure.

    Science.gov (United States)

    Saeed, Aso; DiBona, Gerald F; Grimberg, Elisabeth; Nguy, Lisa; Mikkelsen, Minne Line Nedergaard; Marcussen, Niels; Guron, Gregor

    2014-03-15

    This study examined the effects of 2 wk of high-NaCl diet on kidney function and dynamic renal blood flow autoregulation (RBFA) in rats with adenine-induced chronic renal failure (ACRF). Male Sprague-Dawley rats received either chow containing adenine or were pair-fed an identical diet without adenine (controls). After 10 wk, rats were randomized to either remain on the same diet (0.6% NaCl) or to be switched to high 4% NaCl chow. Two weeks after randomization, renal clearance experiments were performed under isoflurane anesthesia and dynamic RBFA, baroreflex sensitivity (BRS), systolic arterial pressure variability (SAPV), and heart rate variability were assessed by spectral analytical techniques. Rats with ACRF showed marked reductions in glomerular filtration rate and renal blood flow (RBF), whereas mean arterial pressure and SAPV were significantly elevated. In addition, spontaneous BRS was reduced by ∼50% in ACRF animals. High-NaCl diet significantly increased transfer function fractional gain values between arterial pressure and RBF in the frequency range of the myogenic response (0.06-0.09 Hz) only in ACRF animals (0.3 ± 4.0 vs. -4.4 ± 3.8 dB; P renal failure by facilitating pressure transmission to the microvasculature.

  11. Evaluation of the renal blood flow by densitometry using cine-angiograms

    International Nuclear Information System (INIS)

    Nikolaev, G.G.; Slobodzyan, B.M.; Mikhajlov, V.A.

    1983-01-01

    A method of the quantitative determination of the blood flow in the renal artery and the arterial bed of the renal parenchyma was developed basing on roentgenocinematography and subsequent densitometric analysis of a roentgenocinefilm. Advantages of the utilization of this method are considered with reference to two groups of patients with chronic pyelonephritis and hypertension without change of a vascular pattern on the angiograms. They are associated with a possibility of separate determination of the hemodynamics on topographycatly Definite zones of the renal arterial bed and hemodynamic disturbances in morphological changes of the renal vessels that are invisible on the angiogra

  12. Plasma flow in toroidal systems with a separatrix

    International Nuclear Information System (INIS)

    Gribkov, V.M.; Morozov, D.Kh.; Pogutse, O.P.

    1984-01-01

    A hydrodynamic plasma flow in toroidal systems is considered. Rlasma flow lines for various magnetic configurations are calculated. A particular attention is given to studying plasma flow in configurations with two magnetic a axes and a separatrix. The flow picture i the toroidal case is shown to qualita ity to penetrate through the separatrix - the latter becomes ''perforated''. Th he pictkre of these flows is calculated. The plasma diffusion coefficient with account for the separatrix is calculated and is shown not to turn into the infin nity in the toroidal case as well. The plasma flow is analytically considered in the model with distributed current as well as in the model with current conce entrated at the oroidal system axis. In the first case the existence of ''stagnant'' regions near the magnetic axis is established from which the plasma a does not flow out

  13. Acetylcysteine reduces plasma homocysteine concentration and improves pulse pressure and endothelial function in patients with end-stage renal failure

    DEFF Research Database (Denmark)

    Scholze, Alexandra; Rinder, Christiane; Beige, Joachim

    2004-01-01

    Increased oxidative stress, elevated plasma homocysteine concentration, increased pulse pressure, and impaired endothelial function constitute risk factors for increased mortality in patients with end-stage renal failure.......Increased oxidative stress, elevated plasma homocysteine concentration, increased pulse pressure, and impaired endothelial function constitute risk factors for increased mortality in patients with end-stage renal failure....

  14. [Ultrasonographic study of blood flow in the renal arteries of patients with arterial hypertension].

    Science.gov (United States)

    Makarenko, E S; Dombrovskiĭ, V I; Nelasov, N Iu

    2012-01-01

    Vascular duplex ultrasound duplex with simultaneous ECG registration was made to estimate the quantitative and time parameters of blood flow in the renal arteries with grade 1-2 arterial hypertension. There were increases in vascular resistance indices and acceleration phase index and a reduction in systolic phase index. There were correlations of the time parameters of blood flow in the renal arteries with age and lipidogram values.

  15. Evaluation of renal first pass blood flow with a functional image technique in hypertensive patients

    International Nuclear Information System (INIS)

    Ishibashi, Masatoshi; Morita, Seiichiro; Umezaki, Noriyoshi; Ohtake, Hisashi

    1988-01-01

    The renal circulation of patients with essential hypertension and renovascular hypertension was evaluated using 99m Tc-DTPA. The first renal peak count (the first C max ; FC max ), time phase distribution (the first T max ; FT max ), and blood velocity (the FC max /FT max ) were calculated by digital imaging. This yields a visual image of the renal circulation. We consider that the increase in the renal first pass blood flow in patients with essential hypertension is best observed pixel by pixel. The FC max and FC max /FT max images before and after treatment by percutaneous transluminal renal angioplasty in patients with renovascular hypertension clearly show its therapeutic effect. The FI technique, therefore, has the advantage that it can be performed at the same time as the conventional routine examinations of renal function. This makes it very useful clinically. (orig.)

  16. Glucagon-like peptide-1 acutely affects renal blood flow and urinary flow rate in spontaneously hypertensive rats despite significantly reduced renal expression of GLP-1 receptors

    DEFF Research Database (Denmark)

    Ronn, Jonas; Jensen, Elisa P; Wewer Albrechtsen, Nicolai J

    2017-01-01

    to increased mean arterial pressure (MAP) and increased renal blood flow (RBF). In hypertensive animal models, GLP-1 has been reported both to increase and decrease MAP. The aim of this study was to examine expression of renal GLP-1 receptors in spontaneously hypertensive rats (SHR) and to assess the effect......Glucagon-like peptide-1 (GLP-1) is an incretin hormone increasing postprandial insulin release. GLP-1 also induces diuresis and natriuresis in humans and rodents. The GLP-1 receptor is extensively expressed in the renal vascular tree in normotensive rats where acute GLP-1 treatment leads...... in the kidney from SHR. However, acute intrarenal infusion of GLP-1 increased MAP, RBF, dieresis, and natriuresis without affecting heart rate in both rat strains. These results suggest that the acute renal effects of GLP-1 in SHR are caused either by extrarenal GLP-1 receptors activating other mechanisms (e...

  17. Effect of captopril on renal blood flow in renal artery stenosis assessed by positron tomography with rubidium-82

    International Nuclear Information System (INIS)

    Tamaki, N.; Alpert, N.M.; Rabito, C.A.; Barlai-Kovach, M.; Correia, J.A.; Strauss, H.W.

    1988-01-01

    The sequence and magnitude of acute changes in renal blood flow following administration of captopril were determined in a canine model of acute unilateral renal artery stenosis using rubidium-82 and positron emission tomography. Data were recorded in each of nine dogs under three conditions: 1) during a baseline control interval, 2) during renal artery stenosis, and 3) during stenosis with intravenous injection of captopril (1.2 mg/kg). Mean arterial blood pressure was 108 +/- 12 mm Hg at control, increased significantly to 125 +/- 13 mm Hg (p less than 0.01) during stenosis, and decreased to 98 +/- 13 mm/Hg (p less than 0.01) after captopril infusion. Mean renal blood flow was calculated using a steady state single compartment model from the images produced by positron emission tomography. The estimated flow to the affected kidney was 3.37 +/- 1.48 ml/min/g at control, 0.86 +/- 0.62 ml/min/g during stenosis (p less than 0.01), and 0.64 +/- 0.57 ml/min/g after captopril administration (p = NS compared with precaptopril value). The estimated flow to the contralateral kidney was minimally reduced from a baseline of 3.84 +/- 0.95 to 3.24 +/- 1.13 ml/min/g (p = NS) during stenosis and increased after captopril infusion (4.08 +/- 0.94 ml/min/g; p = 0.01). These data suggest that repetitive imaging with positron emission tomography can be used to delineate acute changes in renal perfusion following captopril administration

  18. Anisotropic plasma with flows in tokamak: Steady state and stability

    International Nuclear Information System (INIS)

    Ilgisonis, V.I.

    1996-01-01

    An adequate description of equilibrium and stability of anisotropic plasma with macroscopic flows in tokamaks is presented. The Chew-Goldberger-Low (CGL) approximation is consistently used to analyze anisotropic plasma dynamics. The admissible structure of a stationary flow is found to be the same as in the ideal magnetohydrodynamics with isotropic pressure (MHD), which means an allowance for the same relabeling symmetry as in ideal MHD systems with toroidally nested magnetic surfaces. A generalization of the Grad-Shafranov equation for the case of anisotropic plasma with flows confined in the axisymmetric magnetic field is derived. A variational principle was obtained, which allows for a stability analysis of anisotropic pressure plasma with flows, and takes into account the conservation laws resulting from the relabeling symmetry. This principle covers the previous stability criteria for static CGL plasma and for ideal MHD flows in isotropic plasma as well. copyright 1996 American Institute of Physics

  19. Generation of zonal flows in rotating fluids and magnetized plasmas

    DEFF Research Database (Denmark)

    Juul Rasmussen, J.; Garcia, O.E.; Naulin, V.

    2006-01-01

    The spontaneous generation of large-scale flows by the rectification of small-scale turbulent fluctuations is of great importance both in geophysical flows and in magnetically confined plasmas. These flows regulate the turbulence and may set up effective transport barriers. In the present....... The analogy to large-scale flow generation in drift-wave turbulence dynamics in magnetized plasma is briefly discussed....

  20. The plasma carnitine concentration regulates renal OCTN2 expression and carnitine transport in rats

    OpenAIRE

    Schürch, R; Todesco, L; Novakova, K; Mevissen, M; Stieger, B; Krähenbühl, S

    2010-01-01

    Previous findings in rats and in human vegetarians suggest that the plasma carnitine concentration and/or carnitine ingestion may influence the renal reabsorption of carnitine. We tested this hypothesis in rats with secondary carnitine deficiency following treatment with N-trimethyl-hydrazine-3-propionate (THP) for 2 weeks and rats treated with excess L-carnitine for 2 weeks. Compared to untreated control rats, treatment with THP was associated with an approximately 70% decrease in plasma car...

  1. Exogenous and endogenous angiotensin-II decrease renal cortical oxygen tension in conscious rats by limiting renal blood flow.

    Science.gov (United States)

    Emans, Tonja W; Janssen, Ben J; Pinkham, Maximilian I; Ow, Connie P C; Evans, Roger G; Joles, Jaap A; Malpas, Simon C; Krediet, C T Paul; Koeners, Maarten P

    2016-11-01

    Our understanding of the mechanisms underlying the role of hypoxia in the initiation and progression of renal disease remains rudimentary. We have developed a method that allows wireless measurement of renal tissue oxygen tension in unrestrained rats. This method provides stable and continuous measurements of cortical tissue oxygen tension (PO2) for more than 2 weeks and can reproducibly detect acute changes in cortical oxygenation. Exogenous angiotensin-II reduced renal cortical tissue PO2 more than equi-pressor doses of phenylephrine, probably because it reduced renal oxygen delivery more than did phenylephrine. Activation of the endogenous renin-angiotensin system in transgenic Cyp1a1Ren2 rats reduced cortical tissue PO2; in this model renal hypoxia precedes the development of structural pathology and can be reversed acutely by an angiotensin-II receptor type 1 antagonist. Angiotensin-II promotes renal hypoxia, which may in turn contribute to its pathological effects during development of chronic kidney disease. We hypothesised that both exogenous and endogenous angiotensin-II (AngII) can decrease the partial pressure of oxygen (PO2) in the renal cortex of unrestrained rats, which might in turn contribute to the progression of chronic kidney disease. Rats were instrumented with telemeters equipped with a carbon paste electrode for continuous measurement of renal cortical tissue PO2. The method reproducibly detected acute changes in cortical oxygenation induced by systemic hyperoxia and hypoxia. In conscious rats, renal cortical PO2 was dose-dependently reduced by intravenous AngII. Reductions in PO2 were significantly greater than those induced by equi-pressor doses of phenylephrine. In anaesthetised rats, renal oxygen consumption was not affected, and filtration fraction was increased only in the AngII infused animals. Oxygen delivery decreased by 50% after infusion of AngII and renal blood flow (RBF) fell by 3.3 ml min -1 . Equi-pressor infusion of

  2. Exogenous and endogenous angiotensin‐II decrease renal cortical oxygen tension in conscious rats by limiting renal blood flow

    Science.gov (United States)

    Emans, Tonja W.; Janssen, Ben J.; Pinkham, Maximilian I.; Ow, Connie P. C.; Evans, Roger G.; Joles, Jaap A.; Malpas, Simon C.; Krediet, C. T. Paul

    2016-01-01

    Key points Our understanding of the mechanisms underlying the role of hypoxia in the initiation and progression of renal disease remains rudimentary.We have developed a method that allows wireless measurement of renal tissue oxygen tension in unrestrained rats.This method provides stable and continuous measurements of cortical tissue oxygen tension (PO2) for more than 2 weeks and can reproducibly detect acute changes in cortical oxygenation.Exogenous angiotensin‐II reduced renal cortical tissue PO2 more than equi‐pressor doses of phenylephrine, probably because it reduced renal oxygen delivery more than did phenylephrine.Activation of the endogenous renin–angiotensin system in transgenic Cyp1a1Ren2 rats reduced cortical tissue PO2; in this model renal hypoxia precedes the development of structural pathology and can be reversed acutely by an angiotensin‐II receptor type 1 antagonist.Angiotensin‐II promotes renal hypoxia, which may in turn contribute to its pathological effects during development of chronic kidney disease. Abstract We hypothesised that both exogenous and endogenous angiotensin‐II (AngII) can decrease the partial pressure of oxygen (PO2) in the renal cortex of unrestrained rats, which might in turn contribute to the progression of chronic kidney disease. Rats were instrumented with telemeters equipped with a carbon paste electrode for continuous measurement of renal cortical tissue PO2. The method reproducibly detected acute changes in cortical oxygenation induced by systemic hyperoxia and hypoxia. In conscious rats, renal cortical PO2 was dose‐dependently reduced by intravenous AngII. Reductions in PO2 were significantly greater than those induced by equi‐pressor doses of phenylephrine. In anaesthetised rats, renal oxygen consumption was not affected, and filtration fraction was increased only in the AngII infused animals. Oxygen delivery decreased by 50% after infusion of AngII and renal blood flow (RBF) fell by 3.3 ml min−1

  3. Value of downstream circulation in renal artery stenosis with arterial hypertension: comparison between color Doppler flow and digital renal angiography in 123 patients

    International Nuclear Information System (INIS)

    Grataloup, C.; Challande, P.; Plainfosse, M.C.; Girerd, X.; Belattar, K.; Plouin, P.F.

    1996-01-01

    Digital renal angiography and color Doppler flow were compared for diagnosis of renal artery stenosis in 123 hypertensive patients with a prevalence of renal artery stenosis ≥75% of 21 %. Only color Doppler flow signs found downstream from the stenosis could be quantified. A rising time (RT) >0.07 s was the best marker for renal artery stenosis ≥ 75 % according to a receiver operating characteristic curve with a specificity of 97 %, a sensitivity of 88 %, a positive predictive value of 86 %, a negative predictive value of 98 % and an accuracy of 96 %. Digital renal angiography and color Doppler flow findings for renal artery lesions were classified into 4 degrees with agreement for 86 % of the kidneys. (authors). 13 refs., 5 figs., 8 tabs

  4. Plasma lipoproteins and renal function during simvastatin treatment in diabetic nephropathy

    DEFF Research Database (Denmark)

    Hommel, E; Andersen, P; Gall, M A

    1992-01-01

    The aim of this study was to assess the effect of simvastatin on plasma lipoproteins and renal function in hypercholesterolaemic Type 1 (insulin-dependent) diabetic patients with diabetic nephropathy. Twenty-six hypercholesterolaemic (total cholesterol greater than or equal to 5.5 mmol/l) Type 1...

  5. Relation between plasma plume density and gas flow velocity in atmospheric pressure plasma

    International Nuclear Information System (INIS)

    Yambe, Kiyoyuki; Taka, Shogo; Ogura, Kazuo

    2014-01-01

    We have studied atmospheric pressure plasma generated using a quartz tube, helium gas, and copper foil electrode by applying RF high voltage. The atmospheric pressure plasma in the form of a bullet is released as a plume into the atmosphere. To study the properties of the plasma plume, the plasma plume current is estimated from the difference in currents on the circuit, and the drift velocity is measured using a photodetector. The relation of the plasma plume density n plu , which is estimated from the current and the drift velocity, and the gas flow velocity v gas is examined. It is found that the dependence of the density on the gas flow velocity has relations of n plu ∝ log(v gas ). However, the plasma plume density in the laminar flow is higher than that in the turbulent flow. Consequently, in the laminar flow, the density increases with increasing the gas flow velocity

  6. On the interplay between turbulence and poloidal flows in plasmas

    International Nuclear Information System (INIS)

    Hidalgo, C.; Pedrosa, M.A.; Garcia-Cortes, I.

    1999-01-01

    The radial profile of Reynolds stress has been measured in the plasma boundary region of tokamaks and stellarator plasmas. The electrostatic Reynolds stress (proportional to r E-tilde θ >) shows a radial gradient close to the velocity shear layer location, showing that this mechanism can drive significant poloidal flows in the plasma boundary region of fusion plasmas. The generation of poloidal flows by Ion Bernstein Wave (IBW) is under investigation in toroidal plasmas. The radial gradient in the Reynolds stress increases with RF power and radial electric fields are modified at the RF resonance layer. (author)

  7. Plasma Flows in Crossed Magnetic and Electric Fields

    International Nuclear Information System (INIS)

    Belikov, A.G.

    2005-01-01

    The effect of the magnitude and direction of an external electric field on the plasma flowing through a magnetic barrier is studied by numerically solving two-fluid MHD equations. The drift velocity of the plasma flow and the distribution of the flow electrons over transverse velocities are found to depend on the magnitude and direction of the electric field. It is shown that the direction of the induced longitudinal electric field is determined by the direction of the external field and that the electric current generated by the plasma flow significantly disturbs the barrier field

  8. Effects of levosimendan on glomerular filtration rate, renal blood flow, and renal oxygenation after cardiac surgery with cardiopulmonary bypass: a randomized placebo-controlled study.

    Science.gov (United States)

    Bragadottir, Gudrun; Redfors, Bengt; Ricksten, Sven-Erik

    2013-10-01

    Acute kidney injury develops in a large proportion of patients after cardiac surgery because of the low cardiac output syndrome. The inodilator levosimendan increases cardiac output after cardiac surgery with cardiopulmonary bypass, but a detailed analysis of its effects on renal perfusion, glomerular filtration, and renal oxygenation in this group of patients is lacking. We therefore evaluated the effects of levosimendan on renal blood flow, glomerular filtration rate, renal oxygen consumption, and renal oxygen demand/supply relationship, i.e., renal oxygen extraction, early after cardiac surgery with cardiopulmonary bypass. Prospective, placebo-controlled, and randomized trial. Cardiothoracic ICU of a tertiary center. Postcardiac surgery patients (n=30). The patients were randomized to receive levosimendan, 0.1 µg/kg/min after a loading dose of 12 µg/kg (n=15), or placebo (n=15). The experimental procedure started 4-6 hours after surgery in the ICU during propofol sedation and mechanical ventilation. Systemic hemodynamic were evaluated by a pulmonary artery thermodilution catheter. Renal blood flow and glomerular filtration rate were measured by the renal vein retrograde thermodilution technique and by renal extraction of Cr-EDTA, respectively. Central venous pressure was kept constant by colloid/crystalloid infusion. Compared to placebo, levosimendan increased cardiac index (22%), stroke volume index (15%), and heart rate (7%) and decreased systemic vascular resistance index (21%), whereas mean arterial pressure was not affected. Levosimendan induced significant increases in renal blood flow (12%, prenal vascular resistance (18%, prenal oxygen consumption, or renal oxygen extraction, compared to placebo. After cardiac surgery with cardiopulmonary bypass, levosimendan induces a vasodilation, preferentially of preglomerular resistance vessels, increasing both renal blood flow and glomerular filtration rate without jeopardizing renal oxygenation. Due to its

  9. Synchronized renal blood flow dynamics mapped with wavelet analysis of laser speckle flowmetry data

    DEFF Research Database (Denmark)

    Brazhe, Alexey R; Marsh, Donald J; von Holstein-Rathlou, Niels-Henrik

    2014-01-01

    of rat kidneys. The regulatory mechanism in the renal microcirculation generates oscillations in arterial blood flow at several characteristic frequencies. Our approach to laser speckle image processing allows detection of frequency and phase entrainments, visualization of their patterns, and estimation......Full-field laser speckle microscopy provides real-time imaging of superficial blood flow rate. Here we apply continuous wavelet transform to time series of speckle-estimated blood flow from each pixel of the images to map synchronous patterns in instantaneous frequency and phase on the surface...... of the extent of synchronization in renal cortex dynamics....

  10. Renal blood flow after transplantation: Effects of acute tubular necrosis, rejection, and cyclosporine toxicity

    International Nuclear Information System (INIS)

    Lear, J.L.; Raff, U.; Jain, R.; Horgan, J.G.

    1988-01-01

    The authors incorporated their recently developed radionuclide first pass-technique for the quantitative measurement of renal transplant perfusion into routine DTPA imaging. Using this technique they investigated the effects of acute tubular necrosis (ATN), rejection, and cyclosporing toxicity on renal blood flow in a series of 80 studies in 35 patients, with independent evaluation of renal function. Transplant flow values were as follows: normal functioning, 439 mL/min +-83; ATN 248 mL/min +-63; rejection, 128 mL/min +-58; cyclosporing toxicity, 284 mL/min +-97; (normal flow in nontransplanted kidneys, approximately 550 mL/min). Differences between normal functioning, ATN, and rejection were significant (P < .05). Interestingly, immediate postsurgical hyperemia frequently occurred, with flow values sometimes exceeding 700 mL/min

  11. Thin film plasma coatings from dielectric free-flowing materials

    International Nuclear Information System (INIS)

    Timofeeva, L.A.; Katrich, S.A.; Solntsev, L.A.

    1994-01-01

    Fabrication of thin film plasma coatings from insulating free-flowing materials is considered. Molybdenum-tart ammonium coating of 3...5 μ thickness deposited on glassy carbon, aluminium, silicon, nickel, cast iron and steel substrates in 'Bulat-ZT' machine using insulating free-flowing materials cathod was found to form due to adsorption, absorption and dissuasion processes. The use of insulating free-flowing materials coatings allow to exclude pure metals cathods in plasma-plating process

  12. Effect of Energetic Plasma Flux on Flowing Liquid Lithium Surfaces

    Science.gov (United States)

    Kalathiparambil, Kishor; Jung, Soonwook; Christenson, Michael; Fiflis, Peter; Xu, Wenyu; Szott, Mathew; Ruzic, David

    2014-10-01

    An operational liquid lithium system with steady state flow driven by thermo-electric magneto-hydrodynamic force and capable of constantly refreshing the plasma exposed surface have been demonstrated at U of I. To evaluate the system performance in reactor relevant conditions, specifically to understand the effect of disruptive plasma events on the performance of the liquid metal PFCs, the setup was integrated to a pulsed plasma generator. A coaxial plasma generator drives the plasma towards a theta pinch which preferentially heats the ions, simulating ELM like flux, and the plasma is further guided towards the target chamber which houses the flowing lithium system. The effect of the incident flux is examined using diagnostic tools including triple Langmuir probe, calorimeter, rogowski coils, Ion energy analyzers, and fast frame spectral image acquisition with specific optical filters. The plasma have been well characterized and a density of ~1021 m-3, with electron temperature ~10 - 20 eV is measured, and final plasma velocities of 34 - 74 kms-1 have been observed. Calorimetric measurements using planar molybdenum targets indicate a maximum plasma energy (with 6 kV plasma gun and 20 kV theta pinch) of 0.08 MJm-2 with plasma divergence effects resulting in marginal reduction of 40 +/- 23 J in plasma energy. Further results from the other diagnostic tools, using the flowing lithium targets and the planar targets coated with lithium will be presented. DOE DE-SC0008587.

  13. Effects of fenoldopam on renal blood flow in hypertensive chronic kidney disease.

    Science.gov (United States)

    Rovella, Valentina; Ferrannini, Michele; Tesauro, Manfredi; Marrone, Giulia; Busca, Andrea; Sorge, Roberto; Manca di Villahermosa, Simone; Casasco, Maurizio; Di Daniele, Nicola; Noce, Annalisa

    2018-05-15

    The synthetic drug fenoldopam mesylate (FM) may have a renoprotective role, and a "renal dose" of 0.1 µg/kg/min intravenous (IV) infusion of FM has been reported as able to increase renal blood flow without affecting systemic blood pressure. But conclusive data are still lacking. We aimed to investigate by color-Doppler ultrasonography the effects of IV administration of FM at this dosage in hypertensive chronic kidney disease (CKD) patients, and verify whether it may induce any systemic hemodynamic alteration. In 60 hypertensive CKD patients, we measured by duplex Doppler ultrasonography, at baseline and during infusion of 0.1 µg/kg/min of FM, the systolic and diastolic flow velocity (sampled at the renal hilum, intermediate section and origin of both renal arteries) and the intra-parenchymal renal resistive index (RRI) sampled on interlobular arteries of both kidneys. Patients were divided into four subgroups (I-IV) according to classification of National Kidney Foundation Kidney Disease Outcomes Quality Initiative (NKF-DOQI). Infusion of 0.1 µg/kg/min FM significantly decreased the RRI (0.73 ± 0.05 vs. 0.65 ± 0.06; p flow velocities in all renal artery tracts examined. No single episode of systemic hypotension was observed. Very low-dose FM may significantly increase renal blood flow and exert a renal protective effect in hypertensive CKD patients. Infusion of FM at such low dosage appears also to be quite safe, even in CKD and hypertensive patients.

  14. Effects of Restoration of Blood Flow on the Development of Aortic Atherosclerosis in ApoE-/- Mice With Unilateral Renal Artery Stenosis.

    Science.gov (United States)

    Pathak, Alokkumar S; Huang, Jianhua; Rojas, Mauricio; Bazemore, Taylor C; Zhou, Ruihai; Stouffer, George A

    2016-04-03

    Chronic unilateral renal artery stenosis (RAS) causes accelerated atherosclerosis in apolipoprotein E-deficient (ApoE(-/-)) mice, but effects of restoration of renal blood flow on aortic atherosclerosis are unknown. Male ApoE(-/-) mice underwent sham surgery (n=16) or had partial ligation of the right renal artery (n=41) with the ligature being removed 4 days later (D4LR; n=6), 8 days later (D8LR; n=11), or left in place for 90 days (chronic RAS; n=24). Ligature removal at 4 or 8 days resulted in improved renal blood flow, decreased plasma angiotensin II levels, a return of systolic blood pressure to baseline, and increased plasma levels of neutrophil gelatinase associated lipocalin. Chronic RAS resulted in increased lipid staining in the aortic arch (33.2% [24.4, 47.5] vs 11.6% [6.1, 14.2]; Prenal blood flow at either 4 or 8 days after unilateral RAS had a beneficial effect on systolic blood pressure, aortic lipid deposition, and atheroma inflammation. © 2016 The Authors. Published on behalf of the American Heart Association, Inc., by Wiley Blackwell.

  15. Renal blood flow, fractional excretion of sodium and acute kidney injury: time for a new paradigm?

    Science.gov (United States)

    Prowle, John; Bagshaw, Sean M; Bellomo, Rinaldo

    2012-12-01

    Global renal blood flow is considered pivotal to renal function. Decreased global renal blood flow (decreased perfusion) is further considered the major mechanism of reduced glomerular filtration rate responsible for the development of acute kidney injury (AKI) in critically ill patients. Additionally, urinary biochemical tests are widely taught to allow the differential diagnosis of prerenal (functional) AKI and intrinsic [structural AKI (so-called acute tubular necrosis)]. In this review we will examine recent evidence regarding these two key clinical paradigms. Recent animal experiments and clinical studies in humans using cine-phase contrast magnetic resonance technology are not consistent with the decreased perfusion paradigm. They suggest instead that changes in the intra-renal circulation including modification in efferent arteriolar function and intra-renal shunting are much more likely to be responsible for AKI, especially in sepsis. Similarly, recent human studies indicate the urinary biochemistry has limited diagnostic or prognostic ability and is dissociated form biomarker and microscopic evidence of tubular injury. Intra-renal microcirculatory changes are likely more important than changes in global blood flow in the development of AKI. Urinary biochemistry is not a clinically useful diagnostic or prognostic tool in critically ill patients at risk of or with AKI.

  16. Vasomotion of renal blood flow in essential hypertension. Oscillations in xenon transit

    International Nuclear Information System (INIS)

    Hollenberg, N.K.; Sandor, T.

    1984-01-01

    To assess the frequency and magnitude of phasic renal blood flow changes in essential hypertension, we applied an analytical method based on the estimation of power spectral density to xenon transit through the kidney. Despite similar age and gender distribution of the patients and exclusion of those with accelerated hypertension, mean renal blood flow was significantly lower in 100 patients with essential hypertension (299 +/- 8 ml/100 g/min) than in the 144 normal subjects (335 +/- 6 ml/100 g/min; p less than 0.001). Normalized power, the index of oscillatory behavior, was more than twice normal in patients with essential hypertension (p less than 0.001), but there was no difference in the frequency or cycle length of the oscillation. Two maneuvers that induced renal vasoconstriction, the application of cuffs to the thighs which were then inflated to diastolic blood pressure and an emotional provocation, reduced renal blood flow much more in patients with essential hypertension (p less than 0.01) in association with a striking increase in normalized power (p less than 0.001). The oscillations, which reflected not the phasic blood pressure change but rather the phasic change in renal perfusion, provided additional evidence that renal vasoconstriction plays an active role in the pathogenesis of essential hypertension

  17. MR measures of renal perfusion, oxygen bioavailability and total renal blood flow in a porcine model: noninvasive regional assessment of renal function.

    Science.gov (United States)

    Wentland, Andrew L; Artz, Nathan S; Fain, Sean B; Grist, Thomas M; Djamali, Arjang; Sadowski, Elizabeth A

    2012-01-01

    Magnetic resonance imaging (MRI) may be a useful adjunct to current methods of evaluating renal function. MRI is a noninvasive imaging modality that has the ability to evaluate the kidneys regionally, which is lacking in current clinical methods. Other investigators have evaluated renal function with MRI-based measurements, such as with techniques to measure cortical and medullary perfusion, oxygen bioavailability and total renal blood flow (TRBF). However, use of all three techniques simultaneously, and therefore the relationships between these MRI-derived functional parameters, have not been reported previously. To evaluate the ability of these MRI techniques to track changes in renal function, we scanned 11 swine during a state of hyperperfusion with acetylcholine and a saline bolus and subsequently scanned during a state of hypoperfusion with the prolonged use of isoflurane anesthesia. For each time point, measurements of perfusion, oxygen bioavailability and TRBF were acquired. Measurements of perfusion and oxygen bioavailability were compared with measurements of TRBF for all swine across all time points. Cortical perfusion, cortical oxygen bioavailability, medullary oxygen bioavailability and TRBF significantly increased with the acetylcholine challenge. Cortical perfusion, medullary perfusion, cortical oxygen bioavailability and TRBF significantly decreased during isoflurane anesthesia. Cortical perfusion (Spearman's correlation coefficient = 0.68; P renal function. Maintenance of the medullary oxygen bioavailability in low blood flow states may reflect the autoregulation particular to this region of the kidney. The ability to non-invasively measure all three parameters of kidney function in a single MRI examination and to evaluate the relationships between these functional parameters is potentially useful for evaluating the state of the human kidneys in situ in future studies.

  18. Research status of fast flows and shocks in laboratory plasmas. Supersonic plasma flow and shock waves in various magnetic channels

    International Nuclear Information System (INIS)

    Inutake, Masaaki; Ando, Akira

    2007-01-01

    Fast plasma flow is produced by Magneto-Plasma-Dynamic Arcjet (MPDA). The properties of fast flow and shock wave in various magnetic channels are reported by the experiment results. Fast plasma flow by MPDA, shocked flow in the magnetic channel, supersonic plasma flow in the divergence magnetic nozzle, ion acoustic wave in the mirror field, transonic flow and sonic throat in the magnetic Laval nozzle, fast flow in the helical magnetic channel, and future subjects are reported. Formation of the supersonic plasma flow by the divergence magnetic nozzle and effects of background gas, helical-kink instability in the fast plasma jet, and formation of convergence magnetic nozzle near outlet are described. From the phase difference of azimuthal and axial probe array signals, the plasma has twisted structure and it rotates in the same direction of the twist. Section of MPDA, principle of magnetic acceleration of MPDA, HITOP, relation among velocities, temperature, and Mach number of He ion and atom and the discharge current, distribution of magnetic-flux density in the direction of electromagnetic field, measurement of magnetic field near MPDA exit are illustrated. (S.Y.)

  19. Secretory NaCl and volume flow in renal tubules.

    Science.gov (United States)

    Beyenbach, K W

    1986-05-01

    This review attempts to give a retrospective survey of the available evidence concerning the secretion of NaCl and fluid in renal tubules of the vertebrate kidney. In the absence of glomerular filtration, epithelial secretory mechanisms, which to this date have not been elucidated, are responsible for the renal excretion of NaCl and water in aglomerular fish. However, proximal tubules isolated from glomerular fish kidneys of the flounder, killifish, and the shark also have the capacity to secrete NaCl and fluid. In shark proximal tubules, fluid secretion appears to be driven via secondary active transport of Cl. In another marine vertebrate, the sea snake, secretion of Na (presumably NaCl) and fluid is observed in freshwater-adapted and water-loaded animals. Proximal tubules of mammals can be made to secrete NaCl in vitro together with secretion of aryl acids. An epithelial cell line derived from dog kidney exhibits secondary active secretion of Cl when stimulated with catecholamines. Tubular secretion of NaCl and fluid may serve a variety of renal functions, all of which are considered here. The occurrence of NaCl and fluid secretion in glomerular proximal tubules of teleosts, elasmobranchs, and reptiles and in mammalian renal tissue cultures suggests that the genetic potential for NaCl secretion is present in every vertebrate kidney.

  20. Changes of renal blood flow after ESWL: Assessment by ASL MR imaging, contrast enhanced MR imaging, and renal resistive index

    Energy Technology Data Exchange (ETDEWEB)

    Abd Ellah, Mohamed, E-mail: dr_m_hamdy2006@hotmail.co [Innsbruck Medical University, Radiology Dept., Anich St. 35, 6020 Innsbruck (Austria); Kremser, Christian, E-mail: christian.kremser@i-med.ac.a [Innsbruck Medical University, Radiology Dept., Anich St. 35, 6020 Innsbruck (Austria); Pallwein, Leo, E-mail: leo.pallwein-prettner@uki.a [Innsbruck Medical University, Radiology Dept., Anich St. 35, 6020 Innsbruck (Austria); Aigner, Friedrich, E-mail: friedrich.Aigner@uki.a [Innsbruck Medical University, Radiology Dept., Anich St. 35, 6020 Innsbruck (Austria); Schocke, Michael, E-mail: michael.schocke@i-med.ac.a [Innsbruck Medical University, Radiology Dept., Anich St. 35, 6020 Innsbruck (Austria); Peschel, Reinhard, E-mail: reinhard.peschel@uki.a [Innsbruck Medical University, Urology Dept., Anich St. 35, 6020 Innsbruck (Austria); Pedross, Florian, E-mail: florian.pedross@i-med.ac.a [Innsbruck Medical University, Medical Statistics Dept., Anich St. 35, 6020 Innsbruck (Austria); Pinggera, Germar-Michael, E-mail: germar.pinggera@uki.a [Innsbruck Medical University, Urology Dept., Anich St. 35, 6020 Innsbruck (Austria); Wolf, Christian, E-mail: christian.wolf@bkh-reutte.a [Innsbruck Medical University, Radiology Dept., Anich St. 35, 6020 Innsbruck (Austria); Alsharkawy, Mostafa A.M., E-mail: drmostafamri@yahoo.co [Assiut University, Radiology Dept., Assiut (Egypt); Jaschke, Werner, E-mail: werner.jaschke@i-med.ac.a [Innsbruck Medical University, Radiology Dept., Anich St. 35, 6020 Innsbruck (Austria); Frauscher, Ferdinand, E-mail: ferdinand.frauscher@uki.a [Innsbruck Medical University, Radiology Dept., Anich St. 35, 6020 Innsbruck (Austria)

    2010-10-15

    The annual incidence of stone formation is increased in the industrialised world. Extracorporeal shockwave lithotripsy is a non-invasive effective treatment of upper urinary tract stones. This study is aimed to evaluate changes of renal blood flow in patients undergoing extracorporeal shock wave lithotripsy (ESWL) by arterial spin labeling (ASL) MR imaging, contrast enhanced dynamic MR imaging, and renal resistive index (RI). Thirteen patients with nephrolithiasis were examined using MR imaging and Doppler ultrasound 12 h before and 12 h after ESWL. ASL sequence was done for both kidneys and followed by contrast enhanced MR imaging. In addition RI Doppler ultrasound measurements were performed. A significant increase in RI (p < 0.001) was found in both treated and untreated kidneys. ASL MR imaging also showed significant changes in both kidneys (p < 0.001). Contrast enhanced dynamic MR imaging did not show significant changes in the kidneys. ESWL causes changes in RI and ASL MR imaging, which seem to reflect changes in renal blood flow.

  1. Renal cortical and medullary blood flow responses to altered NO-availability in humans

    DEFF Research Database (Denmark)

    Damkjaer, Mads; Vafaee, Manoucher; Møller, Michael Lehd

    2010-01-01

    The objective was to quantify regional renal blood flow in humans. In nine young volunteers on a controlled diet, the lower abdomen was CT-scanned and regional renal blood flow determined by positron emission tomography (PET) scanning using H(2)(15)O as tracer. Measurements were performed...... of one voxel were eliminated stepwise from the external surface of the VOI ('voxel peeling'), and the blood flow subsequently determined in each new, reduced VOI. Blood flow in the shrinking volumes of interest (VOIs) decreased as the number of cycles of voxel peeling increased. After 4-5 cycles, blood...... flow was not reduced further by additional voxel peeling. This volume-insensitive flow was measured to be 2.30 ±0.17 ml·(g·min)(-1) during the control period; it increased during infusion of glyceryl nitrate to 2.97 ±0.18 ml·(g·min)(-1) (p...

  2. Pyrolysis of methane in flowing microwave plasma. Pt. 1, 2

    International Nuclear Information System (INIS)

    Carmi, U.; Inor, A.A.; Avni, R.; Nickel, H.

    1978-04-01

    The flowing microwave (2.45 G Hz) plasmas of methane and methane-argon mixtures were analyzed by the electrical double floating probe system (DFPS), along the flow stream. The measured electric variables of the microwave plasma were: current, current density, electric field strength, electron temperature, positive ion and electron concentrations. They indicate an irreversible process, of the polymerization of CH 4 and CH 4 +Ar mixtures, taking place in the plasma. The polymerization process reaches its maximum 'down stream'. after the position of the microwave cavity. The polymerization was correlated to the concentration of ions and electrons in the plasma. (orig.) [de

  3. Metal droplet erosion and shielding plasma layer under plasma flows typical of transient processes in tokamaks

    Energy Technology Data Exchange (ETDEWEB)

    Martynenko, Yu. V., E-mail: Martynenko-YV@nrcki.ru [National Research Nuclear University “MEPhI” (Russian Federation)

    2017-03-15

    It is shown that the shielding plasma layer and metal droplet erosion in tokamaks are closely interrelated, because shielding plasma forms from the evaporated metal droplets, while droplet erosion is caused by the shielding plasma flow over the melted metal surface. Analysis of experimental data and theoretical models of these processes is presented.

  4. Control of open end plasma flow utilizing orbital stochasticity

    International Nuclear Information System (INIS)

    Hojo, Hitoshi

    1995-01-01

    It has been known that the control of plasma outside the confinement region of diverter plasma and others in a magnetic field confinement device is very important for improveing the confinement of bulk plasma. The control of plasma outside a confinement region bears two roles, one is the reduction of the thermal load on a diverter plate and others due to the plasma particles lost from the confinement region, and another is the restriction of the back flow of cold plasma and impurities generated outside the confinement region to a bulk plasma region. In this study, the new method of controlling plasma outside a confinement region called magnetic diverter is considered. To the plasma particles advancing along magnetic force lines, the reflection and capture of the plasma particles occur in the region of orbital stochasticity, and the thermal load on an end plate and the reverse flow to a bulk plasma region are restricted. The numerical computation model used regarding the particle control utilizing the orbital stochasticity and the results of calculating the orbit of plasma particles in a magnetic field are reported. (K.I.)

  5. Cyclooxygenase-2 Selectively Controls Renal Blood Flow Through a Novel PPARβ/δ-Dependent Vasodilator Pathway.

    Science.gov (United States)

    Kirkby, Nicholas S; Sampaio, Walkyria; Etelvino, Gisele; Alves, Daniele T; Anders, Katie L; Temponi, Rafael; Shala, Fisnik; Nair, Anitha S; Ahmetaj-Shala, Blerina; Jiao, Jing; Herschman, Harvey R; Xiaomeng, Wang; Wahli, Walter; Santos, Robson A; Mitchell, Jane A

    2018-02-01

    Cyclooxygenase-2 (COX-2) is an inducible enzyme expressed in inflammation and cancer targeted by nonsteroidal anti-inflammatory drugs. COX-2 is also expressed constitutively in discreet locations where its inhibition drives gastrointestinal and cardiovascular/renal side effects. Constitutive COX-2 expression in the kidney regulates renal function and blood flow; however, the global relevance of the kidney versus other tissues to COX-2-dependent blood flow regulation is not known. Here, we used a microsphere deposition technique and pharmacological COX-2 inhibition to map the contribution of COX-2 to regional blood flow in mice and compared this to COX-2 expression patterns using luciferase reporter mice. Across all tissues studied, COX-2 inhibition altered blood flow predominantly in the kidney, with some effects also seen in the spleen, adipose, and testes. Of these sites, only the kidney displayed appreciable local COX-2 expression. As the main site where COX-2 regulates blood flow, we next analyzed the pathways involved in kidney vascular responses using a novel technique of video imaging small arteries in living tissue slices. We found that the protective effect of COX-2 on renal vascular function was associated with prostacyclin signaling through PPARβ/δ (peroxisome proliferator-activated receptor-β/δ). These data demonstrate the kidney as the principle site in the body where local COX-2 controls blood flow and identifies a previously unreported PPARβ/δ-mediated renal vasodilator pathway as the mechanism. These findings have direct relevance to the renal and cardiovascular side effects of drugs that inhibit COX-2, as well as the potential of the COX-2/prostacyclin/PPARβ/δ axis as a therapeutic target in renal disease. © 2018 The Authors.

  6. Generator of the low-temperature heterogeneous plasma flow

    Science.gov (United States)

    Yusupov, D. I.; Gadzhiev, M. Kh; Tyuftyaev, A. S.; Chinnov, V. F.; Sargsyan, M. A.

    2018-01-01

    A generator of low-temperature dc plasma with an expanding channel of an output electrode for gas-thermal spraying was designed and constructed. The delivery of the sprayed powder into the cathode and anode arc-binding zones or into the plasma jet below the anode binding was realized. The electrophysical characteristics of both the plasma torch and the heterogeneous plasma flow with Al2O3 powder are studied. It is shown that the current-voltage characteristic (CVC) of a plasma torch depends on the gas flow rate. If the flow rate varies from 1 to 3 g/s, the falling CVC becomes gradually increasing. The speed and temperature of the sprayed powder are determined.

  7. Plasma flow discharge researches at the PIRIT-2000 facility

    International Nuclear Information System (INIS)

    Popkov, N.F.; Ryaslov, E.A.; Kargin, V.I.; Pikar', A.S.; Vorontsov, V.I.; Kotel'nikov, D.V.; Melkozerov, A.V.

    1996-01-01

    Investigation of a plasma flow switch at the PIRIT-2000 fast operating capacitor bank is reported. The maximum current of the plasma flow discharge (PFD) reaches 5 MA, the current rise time being as low as 100 ns. The magnetic field strength of the plasma flow switch (0.15 T) is about 15 times higher than that of the plasma erosion switch used earlier. Both magnetic probe and optical methods were used in the experiments. From the magnetic probes data the propagating velocity of a current carrying shell (205 cm/s) has been derived, while the optical method is used for determining the velocity of a glowing plasma layer. At varying the operation delay in the range 2-10 s the PFD load current rise time increases up to 150-200 ns, the prepulse increment reaching its maximum at the delays higher than 6 s. (J.U.). 5 figs., 5 refs

  8. Plasma flow discharge researches at the PIRIT-2000 facility

    Energy Technology Data Exchange (ETDEWEB)

    Popkov, N F; Ryaslov, E A; Kargin, V I; Pikar` , A S; Vorontsov, V I; Kotel` nikov, D V; Melkozerov, A V [All-Russian Scientific Research Inst. of Experimental Physics, Sarov (Russian Federation)

    1997-12-31

    Investigation of a plasma flow switch at the PIRIT-2000 fast operating capacitor bank is reported. The maximum current of the plasma flow discharge (PFD) reaches 5 MA, the current rise time being as low as 100 ns. The magnetic field strength of the plasma flow switch (0.15 T) is about 15 times higher than that of the plasma erosion switch used earlier. Both magnetic probe and optical methods were used in the experiments. From the magnetic probes data the propagating velocity of a current carrying shell (205 cm/s) has been derived, while the optical method is used for determining the velocity of a glowing plasma layer. At varying the operation delay in the range 2-10 s the PFD load current rise time increases up to 150-200 ns, the prepulse increment reaching its maximum at the delays higher than 6 s. (J.U.). 5 figs., 5 refs.

  9. Nonlinear drift waves in a dusty plasma with sheared flows

    Energy Technology Data Exchange (ETDEWEB)

    Vranjes, J. [K.U. Leuven (Belgium). Center for Plasma Astrophysics; Shukla, R.K. [Ruhr-Univ. Bochum (Germany). Inst. fuer Theoretische Physik IV

    2002-01-01

    Nonlinear properties of dust-modified drift waves and dust-drift waves in a dusty magnetoplasma with equilibrium sheared flows are examined. For this purpose, the relevant nonlinear equations for drift waves are analyzed for various profiles of the perpendicular and parallel plasma flows, and a variety of nonlinear solutions (viz. single and double vortex chains accompanied with zonal flows, tripolar and global vortices), which are driven by nommiform shear flows and nommiform dust density, is presented.

  10. Nonlinear drift waves in a dusty plasma with sheared flows

    International Nuclear Information System (INIS)

    Vranjes, J.; Shukla, R.K.

    2002-01-01

    Nonlinear properties of dust-modified drift waves and dust-drift waves in a dusty magnetoplasma with equilibrium sheared flows are examined. For this purpose, the relevant nonlinear equations for drift waves are analyzed for various profiles of the perpendicular and parallel plasma flows, and a variety of nonlinear solutions (viz. single and double vortex chains accompanied with zonal flows, tripolar and global vortices), which are driven by nommiform shear flows and nommiform dust density, is presented

  11. Plasma flow in the DIII-D divertor

    International Nuclear Information System (INIS)

    Boedo, J.A.; Porter, G.D.; Schaffer, M.J.

    1998-07-01

    Indications that flows in the divertor can exhibit complex behavior have been obtained from 2-D modeling but so far remain mostly unconfirmed by experiment. An important feature of flow physics is that of flow reversal. Flow reversal has been predicted analytically and it is expected when the ionization source arising from neutral or impurity ionization in the divertor region is large, creating a high pressure zone. Plasma flows arise to equilibrate the pressure. A radiative divertor regime has been proposed in order to reduce the heat and particle fluxes to the divertor target plates. In this regime, the energy and momentum of the plasma are dissipated into neutral gas introduced in the divertor region, cooling the plasma by collisional, radiative and other atomic processes so that the plasma becomes detached from the target plates. These regimes have been the subject of extensive studies in DIII-D to evaluate their energy and particle transport properties, but only recently it has been proposed that the energy transport over large regions of the divertor must be dominated by convection instead of conduction. It is therefore important to understand the role of the plasma conditions and geometry on determining the region of convection-dominated plasma in order to properly control the heat and particle fluxes to the target plates and hence, divertor performance. The authors have observed complex structures in the deuterium ion flows in the DIII-D divertor. Features observed include reverse flow, convective flow over a large volume of the divertor and stagnant flow. They have measured large gradients in the plasma potential across the separatrix in the divertor and determined that these gradients induce poloidal flows that can potentially affect the particle balance in the divertor

  12. Effect of additive renin inhibition with aliskiren on renal blood flow in patients with Chronic Heart Failure and Renal Dysfunction (Additive Renin Inhibition with Aliskiren on renal blood flow and Neurohormonal Activation in patients with Chronic Heart Failure and Renal Dysfunction)

    NARCIS (Netherlands)

    Schroten, Nicolas F.; Damman, Kevin; Hemmelder, Marc H.; Voors, Adriaan A.; Navis, Gerjan; Gaillard, Carlo A. J. M.; van Veldhuisen, Dirk J.; van Gilst, Wiek H.; Hillege, Hans L.

    AIMS: We examined the effect of the renin inhibitor, aliskiren, on renal blood flow (RBF) in patients with heart failure with reduced ejection fraction (HFREF) and decreased glomerular filtration rate (GFR). Renal blood flow is the main determinant of GFR in HFREF patients. Both reduced GFR and RBF

  13. Plasma ascorbic acid concentrations in prevalent patients with end-stage renal disease on hemodialysis.

    Science.gov (United States)

    Sirover, William D; Liu, Yuguan; Logan, Amanda; Hunter, Krystal; Benz, Robert L; Prasad, Deepali; Avila, Jose; Venkatchalam, Thaliga; Weisberg, Lawrence S; Handelman, Garry J

    2015-05-01

    To determine the prevalence of vitamin C (ascorbic acid [AA]) deficiency in patients with end-stage renal disease, the effect of supplemental AA on plasma AA concentrations, and the extrinsic and intrinsic factors that affect plasma AA concentrations in this patient population. In study 1, we compared the effect of hemodialysis (HD) on plasma AA concentrations between patients with low and high pre-HD AA concentrations. In study 2, we analyzed kinetic and nonkinetic factors for their association with increased plasma AA concentrations in patients on maintenance HD. Study 1 was performed in a single outpatient HD clinic in Cherry Hill, New Jersey. Study 2 was performed in 4 outpatient HD clinics in Southern New Jersey. In study 1, we collected plasma samples from 8 adult patients on maintenance HD at various time points around their HD treatment and assayed them for AA concentration. In study 2, we enrolled 203 adult patients and measured pre-HD plasma AA concentrations. We ascertained supplemental AA use and assessed dietary AA intake. In study 1, plasma AA concentrations were compared during the intradialytic and interdialytic period. In study 2, pre-HD plasma AA concentrations were correlated with supplement use and demographic factors. Study 1 showed that over the course of a single HD treatment, the plasma AA concentration decreased by a mean (±standard deviation) of 60% (±6.6). In study 2, the median pre-HD plasma AA concentration was 15.7 μM (interquartile range, 8.7-66.8) in patients who did not take a supplement and 50.6 μM (interquartile range, 25.1-88.8) in patients who did take a supplement (P HD plasma AA concentration ≥30 μM. HD depletes plasma AA concentrations, and AA supplementation allows patients to achieve higher plasma AA concentrations. Copyright © 2015 National Kidney Foundation, Inc. Published by Elsevier Inc. All rights reserved.

  14. High energy density Z-pinch plasmas using flow stabilization

    Energy Technology Data Exchange (ETDEWEB)

    Shumlak, U., E-mail: shumlak@uw.edu; Golingo, R. P., E-mail: shumlak@uw.edu; Nelson, B. A., E-mail: shumlak@uw.edu; Bowers, C. A., E-mail: shumlak@uw.edu; Doty, S. A., E-mail: shumlak@uw.edu; Forbes, E. G., E-mail: shumlak@uw.edu; Hughes, M. C., E-mail: shumlak@uw.edu; Kim, B., E-mail: shumlak@uw.edu; Knecht, S. D., E-mail: shumlak@uw.edu; Lambert, K. K., E-mail: shumlak@uw.edu; Lowrie, W., E-mail: shumlak@uw.edu; Ross, M. P., E-mail: shumlak@uw.edu; Weed, J. R., E-mail: shumlak@uw.edu [Aerospace and Energetics Research Program, University of Washington, Seattle, Washington, 98195-2250 (United States)

    2014-12-15

    The ZaP Flow Z-Pinch research project[1] at the University of Washington investigates the effect of sheared flows on MHD instabilities. Axially flowing Z-pinch plasmas are produced that are 100 cm long with a 1 cm radius. The plasma remains quiescent for many radial Alfvén times and axial flow times. The quiescent periods are characterized by low magnetic mode activity measured at several locations along the plasma column and by stationary visible plasma emission. Plasma evolution is modeled with high-resolution simulation codes – Mach2, WARPX, NIMROD, and HiFi. Plasma flow profiles are experimentally measured with a multi-chord ion Doppler spectrometer. A sheared flow profile is observed to be coincident with the quiescent period, and is consistent with classical plasma viscosity. Equilibrium is determined by diagnostic measurements: interferometry for density; spectroscopy for ion temperature, plasma flow, and density[2]; Thomson scattering for electron temperature; Zeeman splitting for internal magnetic field measurements[3]; and fast framing photography for global structure. Wall stabilization has been investigated computationally and experimentally by removing 70% of the surrounding conducting wall to demonstrate no change in stability behavior.[4] Experimental evidence suggests that the plasma lifetime is only limited by plasma supply and current waveform. The flow Z-pinch concept provides an approach to achieve high energy density plasmas,[5] which are large, easy to diagnose, and persist for extended durations. A new experiment, ZaP-HD, has been built to investigate this approach by separating the flow Z-pinch formation from the radial compression using a triaxial-electrode configuration. This innovation allows more detailed investigations of the sheared flow stabilizing effect, and it allows compression to much higher densities than previously achieved on ZaP by reducing the linear density and increasing the pinch current. Experimental results and

  15. Glucagon-like peptide-1 acutely affects renal blood flow and urinary flow rate in spontaneously hypertensive rats despite significantly reduced renal expression of GLP-1 receptors.

    Science.gov (United States)

    Ronn, Jonas; Jensen, Elisa P; Wewer Albrechtsen, Nicolai J; Holst, Jens Juul; Sorensen, Charlotte M

    2017-12-01

    Glucagon-like peptide-1 (GLP-1) is an incretin hormone increasing postprandial insulin release. GLP-1 also induces diuresis and natriuresis in humans and rodents. The GLP-1 receptor is extensively expressed in the renal vascular tree in normotensive rats where acute GLP-1 treatment leads to increased mean arterial pressure (MAP) and increased renal blood flow (RBF). In hypertensive animal models, GLP-1 has been reported both to increase and decrease MAP. The aim of this study was to examine expression of renal GLP-1 receptors in spontaneously hypertensive rats (SHR) and to assess the effect of acute intrarenal infusion of GLP-1. We hypothesized that GLP-1 would increase diuresis and natriuresis and reduce MAP in SHR. Immunohistochemical staining and in situ hybridization for the GLP-1 receptor were used to localize GLP-1 receptors in the kidney. Sevoflurane-anesthetized normotensive Sprague-Dawley rats and SHR received a 20 min intrarenal infusion of GLP-1 and changes in MAP, RBF, heart rate, dieresis, and natriuresis were measured. The vasodilatory effect of GLP-1 was assessed in isolated interlobar arteries from normo- and hypertensive rats. We found no expression of GLP-1 receptors in the kidney from SHR. However, acute intrarenal infusion of GLP-1 increased MAP, RBF, dieresis, and natriuresis without affecting heart rate in both rat strains. These results suggest that the acute renal effects of GLP-1 in SHR are caused either by extrarenal GLP-1 receptors activating other mechanisms (e.g., insulin) to induce the renal changes observed or possibly by an alternative renal GLP-1 receptor. © 2017 The Authors. Physiological Reports published by Wiley Periodicals, Inc. on behalf of The Physiological Society and the American Physiological Society.

  16. [51Cr]EDTA plasma clearance and endogenous creatinine clearance in advanced renal insufficiency

    International Nuclear Information System (INIS)

    Svendsen, U.G.; Munck, O.; Czartoryski, A.; Stafanger, G.

    1978-01-01

    Comparison of [ 51 Cr]EDTA plasma clearance corrected for extrarenal elimination with 24 h endogenous creatinine clearance in patients with advanced renal failure showed that the corrected [ 51 Cr]EDTA clearance was lower than creatinine clearance, and thus might be a better approximation to the glomerular filtration rate in uraemic patients. The corrections cannot be used on [ 51 Cr]EDTA clearance values below the mean extrarenal clearance, averaging 3.7 ml/min. (Auth.)

  17. Renal function and plasma dabigatran level measured at trough by diluted thrombin time assay

    Directory of Open Access Journals (Sweden)

    Marta E. Martinuzzo

    2017-02-01

    Full Text Available Dabigatran etexilate (direct thrombin inhibitor is effective in preventing embolic stroke in patients with atrial fibrillation. It does not require laboratory control, but given the high renal elimination, its measurement in plasma is important in renal failure. The objectives of the study were to verify the analytical quality of the diluted thrombin time assay for measurement of dabigatran plasma concentration (cc, correlate cc with classic coagulation assays, prothrombin time (PT and activated partial thromboplastin time (APTT, and evaluate them according to the creatinine clearance (CLCr. Forty plasma samples of patients (34 consecutive and 6 suspected of drug accumulation receiving dabigatran at 150 (n = 19 or 110 (n = 21 mg/12 hours were collected. Blood samples were drawn at 10-14 hours of the last intake. Dabigatran concentration was determined by diluted thrombin time (HemosIl DTI, Instrumentation Laboratory (IL. PT and APTT (IL were performed on two fotooptical coagulometers, ACL TOP 300 and 500 (IL. DTI presented intra-assay coefficient of variation < 5.4% and inter-assay < 6%, linearity range 0-493 ng/ml. Patients' cc: median 83 (4-945 ng/ml. Individuals with CLCr in the lowest tertile (22.6-46.1 ml/min showed significantly higher median cc: 308 (49-945, compared to the average 72 (12-190 and highest tertile, 60 (4-118 ng/ml. Correlation between cc and APTT or PT were moderate, r2 = 0.59 and -0.66, p < 0.0001, respectively. DTI test allowed us to quantify plasma dabigatran levels, both in patients with normal or altered renal function, representing a useful tool in clinical situations such as renal failure, pre surgery or emergencies

  18. Generalized superconducting flows -- Plasma confinement, organization

    International Nuclear Information System (INIS)

    Mahajan, S.M.

    1997-01-01

    Complete expulsion of magnetic vorticity is used to characterize the superconducting flow. It is shown that a simple, intuitive, but speculative generalization can serve as a paradigm for a variety of organized flows

  19. HEMOFILTRATION AND COUPLED PLASMA FILTRATION ADSORPTION IMPACT ON TACROLIMUS BLOOD CONCENTRATION IN RENAL TRANSPLANT RECIPIENTS

    Directory of Open Access Journals (Sweden)

    A.V. Vatazin

    2014-01-01

    Full Text Available Aim. To study the effect of hemofi ltration and coupled plasma fi ltration adsorption on tacrolimus blood concentration in renal transplant recipients.Methods and results. The study included 8 renal transplant recipients. In these patients immediately after the operation was performed the coupled plasma fi ltration adsorption with hemofiltration using a cartridge Mediasorb to reduce the severity of reperfusion injury. We have found that during this extracorporeal blood correction procedure there was statistically not signifi cant decrease of tacrolimus blood concentration. However, concentration of tacrolimus remained in the therapeutic range even after the procedure and it was not signifi cantly different from the control point С0.Conclusion. Coupled plasma fi ltration adsorption is safe in renal transplant recipients and has no signifi cant impact on tacrolimus blood concentration. However, the downward trend in the concentration of tacrolimus in the course of these procedures, especially in continuous or semicontinuous mode, as well as in patients with low hematocrit and hypoalbuminemia, requires individual monitoring.

  20. Preservation of renal blood flow by the antioxidant EUK-134 in LPS-treated pigs.

    Science.gov (United States)

    Magder, Sheldon; Parthenis, Dimitrios G; Ghouleh, Imad Al

    2015-03-25

    Sepsis is associated with an increase in reactive oxygen species (ROS), however, the precise role of ROS in the septic process remains unknown. We hypothesized that treatment with EUK-134 (manganese-3-methoxy N,N'-bis(salicyclidene)ethylene-diamine chloride), a compound with superoxide dismutase and catalase activity, attenuates the vascular manifestations of sepsis in vivo. Pigs were instrumented to measure cardiac output and blood flow in renal, superior mesenteric and femoral arteries, and portal vein. Animals were treated with saline (control), lipopolysaccharide (LPS; 10 µg·kg-1·h-1), EUK-134, or EUK-134 plus LPS. Results show that an LPS-induced increase in pulmonary artery pressure (PAP) as well as a trend towards lower blood pressure (BP) were both attenuated by EUK-134. Renal blood flow decreased with LPS whereas superior mesenteric, portal and femoral flows did not change. Importantly, EUK-134 decreased the LPS-induced fall in renal blood flow and this was associated with a corresponding decrease in LPS-induced protein nitrotyrosinylation in the kidney. PO2, pH, base excess and systemic vascular resistance fell with LPS and were unaltered by EUK-134. EUK-134 also had no effect on LPS-associated increase in CO. Interestingly, EUK-134 alone resulted in higher CO, BP, PAP, mean circulatory filling pressure, and portal flow than controls. Taken together, these data support a protective role for EUK-134 in the renal circulation in sepsis.

  1. Modeling plasma flow in straight and curved solenoids

    International Nuclear Information System (INIS)

    Boercker, D.B.; Sanders, D.M.; Storer, J.; Falabella, S.

    1991-01-01

    The ''flux-tube'' model originated by Morozov is a very simple and numerically efficient method for simulating ion motion in plasma filters. In order to test its utility as a design tool, we compare the predictions of the model to recent experimental measurements of plasma flow in both straight and curved solenoids

  2. Stability of plasma cylinder with current in a helical plasma flow

    Science.gov (United States)

    Leonovich, Anatoly S.; Kozlov, Daniil A.; Zong, Qiugang

    2018-04-01

    Stability of a plasma cylinder with a current wrapped by a helical plasma flow is studied. Unstable surface modes of magnetohydrodynamic (MHD) oscillations develop at the boundary of the cylinder enwrapped by the plasma flow. Unstable eigenmodes can also develop for which the plasma cylinder is a waveguide. The growth rate of the surface modes is much higher than that for the eigenmodes. It is shown that the asymmetric MHD modes in the plasma cylinder are stable if the velocity of the plasma flow is below a certain threshold. Such a plasma flow velocity threshold is absent for the symmetric modes. They are unstable in any arbitrarily slow plasma flows. For all surface modes there is an upper threshold for the flow velocity above which they are stable. The helicity index of the flow around the plasma cylinder significantly affects both the Mach number dependence of the surface wave growth rate and the velocity threshold values. The higher the index, the lower the upper threshold of the velocity jump above which the surface waves become stable. Calculations have been carried out for the growth rates of unstable oscillations in an equilibrium plasma cylinder with current serving as a model of the low-latitude boundary layer (LLBL) of the Earth's magnetic tail. A tangential discontinuity model is used to simulate the geomagnetic tail boundary. It is shown that the magnetopause in the geotail LLBL is unstable to a surface wave (having the highest growth rate) in low- and medium-speed solar wind flows, but becomes stable to this wave in high-speed flows. However, it can remain weakly unstable to the radiative modes of MHD oscillations.

  3. Three electrode atmospheric pressure plasma jet in helium flow

    Science.gov (United States)

    Maletic, Dejan; Puac, Nevena; Malovic, Gordana; Petrovic, Zoran Lj.

    2015-09-01

    Plasma jets are widely used in various types of applications and lately more and more in the field of plasma medicine. However, it is not only their applicability that distinguishes them from other atmospheric plasma sources, but also the behavior of the plasma. It was shown that plasma plume is not continuous, but discrete set of plasma packages. Here we present iCCD images and current voltage characteristics of a three electrode plasma jet. Our plasma jet has a simple design with body made of glass tube and two transparent electrodes wrapped around it. The additional third metal tip electrode was positioned at 10 and 25 mm in front of the jet nozzle and connected to the same potential as the powered electrode. Power transmitted to the plasma was from 0.5 W to 4.0 W and the helium flow rate was kept constant at 4 slm. For the 10 mm configuration plasma is ignited on the metal tip in the whole period of the excitation signal and in the positive half cycle plasma ``bullet'' is propagating beyond the metal tip. In contrast to that, for the 25 mm configuration at the tip electrode plasma can be seen only in the minimum and maximum of the excitation signal, and there is no plasma ``bullet'' formation. This research has been supported by the Ministry of Education, Science and Technological Development, Republic of Serbia, under projects ON171037 and III41011.

  4. Intraoperative evaluation of renal blood flow during laparoscopic partial nephrectomy with a novel Doppler system.

    Science.gov (United States)

    Mues, Adam C; Okhunov, Zhamshid; Badani, Ketan; Gupta, Mantu; Landman, Jaime

    2010-12-01

    Hemostasis remains a major challenge associated with laparoscopic renal surgery. We evaluated a cost-effective novel Doppler probe (DP) for assessment of vascular control during laparoscopic partial nephrectomy (LPN). We prospectively collected data during LPN procedures. We documented tumor location and size as well as subjective quality of the hilar dissection. The DP was compared with our standard intraoperative ultrasound system (SUS) for the ability to detect blood flow during hilar dissection and to determine parenchymal ischemia around the tumor after clamping of the renal vessels. Twenty patients underwent LPN by a single surgeon. The mean tumor size was 3.0 cm (range: 1.2-6.3 cm). The times to assess the kidney using the SUS and DP were 68.6 seconds (range: 20-155) and 44.5 seconds (range: 15-180), respectively. Evaluation prior to renal hilar clamping demonstrated the presence of blood flow in all 20 patients (100%) using the SUS and in 17 of 20 (85%) using the DP. Similarly, cessation of blood flow with clamping was documented in 100% of cases with SUS and 85% with DP. Persistent flow was detected by both SUS and DP in two patients requiring further dissection and reclamping. Then, both systems detected the absence of flow before tumor resection. With blood flow interruption confirmation, no patient had significant bleeding at the time of renal parenchymal transection. Intraoperative Doppler ultrasound technologies minimize the risk of significant bleeding during LPN. The DP is a small, simple, effective probe that can be used to assess blood flow interruption to the kidney during laparoscopic renal surgery.

  5. Renal blood flow dynamics in inbred rat strains provides insight into autoregulation.

    Science.gov (United States)

    A Mitrou, Nicholas G; Cupples, William A

    2014-01-01

    Renal autoregulation maintains stable renal blood flow in the face of constantly fluctuating blood pressure. Autoregulation is also the only mechanism that protects the delicate glomerular capillaries when blood pressure increases. In order to understand autoregulation, the renal blood flow response to changing blood pressure is studied. The steadystate response of blood flow is informative, but limits investigation of the individual mechanisms of autoregulation. The dynamics of autoregulation can be probed with transfer function analysis. The frequency-domain analysis of autoregulation allows investigators to probe the relative activity of each mechanism of autoregulation. We discuss the methodology and interpretation of transfer function analysis. Autoregulation is routinely studied in the rat, of which there are many inbred strains. There are multiple strains of rat that are either selected or inbred as models of human pathology. We discuss relevant characteristics of Brown Norway, Spontaneously hypertensive, Dahl, and Fawn-Hooded hypertensive rats and explore differences among these strains in blood pressure, dynamic autoregulation, and susceptibility to hypertensive renal injury. Finally we show that the use of transfer function analysis in these rat strains has contributed to our understanding of the physiology and pathophysiology of autoregulation and hypertensive renal disease.Interestingly all these strains demonstrate effective tubuloglomerular feedback suggesting that this mechanism is not sufficient for effective autoregulation. In contrast, obligatory or conditional failure of the myogenic mechanism suggests that this component is both necessary and sufficient for autoregulation.

  6. Transport hysteresis and zonal flow stimulation in magnetized plasmas

    Science.gov (United States)

    Gravier, E.; Lesur, M.; Reveille, T.; Drouot, T.; Médina, J.

    2017-12-01

    A hysteresis in the relationship between zonal flows and electron heating is observed numerically by using gyrokinetic simulations in fusion plasmas. As the electron temperature increases, a first transition occurs, at a given electron/ion temperature ratio, above which zonal flows are much weaker than before the transition, leading to a poorly confined plasma. Beyond this transition, even if the electron temperature is lowered to a moderate value, the plasma fails to recover a dynamic state with strong zonal flows. Then, as the electron temperature decreases further, a new transition appears, at a temperature lower than the first transition, below which the zonal flows are stronger than they were initially. The confinement of the plasma and the heat flux are thus found to be sensitive to the history of the magnetized plasma. These transitions are associated with large exchanges of energy between the modes corresponding to instabilities ( m> 0 ) and zonal flows ( m = 0 ). We also observe that up to the first transition it is possible to use a control method to stimulate the appearance of zonal flows and therefore the confinement of the plasma. Beyond that transition, this control method is no longer effective.

  7. Comparison of the effects of dopamine, dobutamine, and dopexamine upon renal blood flow: a study in normal healthy volunteers.

    OpenAIRE

    Mousdale, S; Clyburn, P A; Mackie, A M; Groves, N D; Rosen, M

    1988-01-01

    1. We compared the effects of dopexamine, dopamine and dobutamine on the heart rate, blood pressure and renal blood flow of six healthy volunteers in an open triple crossover trial. 2. The results suggest that at the dose ranges investigated dopamine was the most effective agent for increasing renal blood flow.

  8. Renal blood flow using arterial spin labelling MRI and calculated filtration fraction in healthy adult kidney donors pre-nephrectomy and post-nephrectomy

    Energy Technology Data Exchange (ETDEWEB)

    Cutajar, Marica; Clark, Christopher A.; Gordon, Isky [University College London, Imaging and Biophysics Unit, Institute of Child Health, London (United Kingdom); Hilton, Rachel; Olsburgh, Jonathon [Renal Unit, Guy' s and St Thomas' NHS Foundation Trust, London (United Kingdom); Marks, Stephen D. [Great Ormond Street Hospital for Children NHS Foundation Trust, Department of Paediatric Nephrology, London (United Kingdom); Thomas, David L. [University College London, Department of Brain Repair and Rehabilitation, Institute of Neurology, London (United Kingdom); Banks, Tina [Great Ormond Street Hospital for Children NHS Foundation Trust, Department of Radiology, London (United Kingdom)

    2015-08-15

    Renal plasma flow (RPF) (derived from renal blood flow, RBF) and glomerular filtration rate (GFR) allow the determination of the filtration fraction (FF), which may have a role as a non-invasive renal biomarker. This is a hypothesis-generating pilot study assessing the effect of nephrectomy on renal function in healthy kidney donors. Eight living kidney donors underwent arterial spin labelling (ASL) magnetic resonance imaging (MRI) and GFR measurement prior to and 1 year after nephrectomy. Chromium-51 labelled ethylenediamine tetraacetic acid ({sup 51}Cr-EDTA) with multi-blood sampling was undertaken and GFR calculated. The RBF and GFR obtained were used to calculate FF. All donors showed an increase in single kidney GFR of 24 - 75 %, and all but two showed an increase in FF (-7 to +52 %) after nephrectomy. The increase in RBF, and hence RPF, post-nephrectomy was not as great as the increase in GFR in seven out of eight donors. As with any pilot study, the small number of donors and their relatively narrow age range are potential limiting factors. The ability to measure RBF, and hence RPF, non-invasively, coupled with GFR measurement, allows calculation of FF, a biomarker that might provide a sensitive indicator of loss of renal reserve in potential donors. (orig.)

  9. Renal blood flow using arterial spin labelling MRI and calculated filtration fraction in healthy adult kidney donors pre-nephrectomy and post-nephrectomy

    International Nuclear Information System (INIS)

    Cutajar, Marica; Clark, Christopher A.; Gordon, Isky; Hilton, Rachel; Olsburgh, Jonathon; Marks, Stephen D.; Thomas, David L.; Banks, Tina

    2015-01-01

    Renal plasma flow (RPF) (derived from renal blood flow, RBF) and glomerular filtration rate (GFR) allow the determination of the filtration fraction (FF), which may have a role as a non-invasive renal biomarker. This is a hypothesis-generating pilot study assessing the effect of nephrectomy on renal function in healthy kidney donors. Eight living kidney donors underwent arterial spin labelling (ASL) magnetic resonance imaging (MRI) and GFR measurement prior to and 1 year after nephrectomy. Chromium-51 labelled ethylenediamine tetraacetic acid ( 51 Cr-EDTA) with multi-blood sampling was undertaken and GFR calculated. The RBF and GFR obtained were used to calculate FF. All donors showed an increase in single kidney GFR of 24 - 75 %, and all but two showed an increase in FF (-7 to +52 %) after nephrectomy. The increase in RBF, and hence RPF, post-nephrectomy was not as great as the increase in GFR in seven out of eight donors. As with any pilot study, the small number of donors and their relatively narrow age range are potential limiting factors. The ability to measure RBF, and hence RPF, non-invasively, coupled with GFR measurement, allows calculation of FF, a biomarker that might provide a sensitive indicator of loss of renal reserve in potential donors. (orig.)

  10. On steady poloidal and toroidal flows in tokamak plasmas

    International Nuclear Information System (INIS)

    McClements, K. G.; Hole, M. J.

    2010-01-01

    The effects of poloidal and toroidal flows on tokamak plasma equilibria are examined in the magnetohydrodynamic limit. ''Transonic'' poloidal flows of the order of the sound speed multiplied by the ratio of poloidal magnetic field to total field B θ /B can cause the (normally elliptic) Grad-Shafranov (GS) equation to become hyperbolic in part of the solution domain. It is pointed out that the range of poloidal flows for which the GS equation is hyperbolic increases with plasma beta and B θ /B, thereby complicating the problem of determining spherical tokamak plasma equilibria with transonic poloidal flows. It is demonstrated that the calculation of the hyperbolicity criterion can be easily modified when the assumption of isentropic flux surfaces is replaced with the more tokamak-relevant one of isothermal flux surfaces. On the basis of the latter assumption, a simple expression is obtained for the variation of density on a flux surface when poloidal and toroidal flows are simultaneously present. Combined with Thomson scattering measurements of density and temperature, this expression could be used to infer information on poloidal and toroidal flows on the high field side of a tokamak plasma, where direct measurements of flows are not generally possible. It is demonstrated that there are four possible solutions of the Bernoulli relation for the plasma density when the flux surfaces are assumed to be isothermal, corresponding to four distinct poloidal flow regimes. Finally, observations and first principles-based theoretical modeling of poloidal flows in tokamak plasmas are briefly reviewed and it is concluded that there is no clear evidence for the occurrence of supersonic poloidal flows.

  11. Energy distribution and transfer in flowing hydrogen microwave plasmas

    International Nuclear Information System (INIS)

    Chapman, R.A.

    1987-01-01

    This thesis is an experimental investigation of the physical and chemical properties of a hydrogen discharge in a flowing microwave plasma system. The plasma system is the mechanisms utilized in an electrothermal propulsion concept to convert electromagnetic energy into the kinetic energy of flowing hydrogen gas. The plasmas are generated inside a 20-cm ID resonant cavity at a driving frequency of 2.45 GHz. The flowing gas is contained in a coaxially positioned 22-mm ID quartz discharge tube. The physical and chemical properties are examined for absorbed powers of 20-100 W, pressures of 0.5-10 torr, and flow rates of 0-10,000 μ-moles/sec. A calorimetry system enclosing the plasma system to accurately measure the energy inputs and outputs has been developed. The rate of energy that is transferred to the hydrogen gas as it flows through the plasma system is determined as a function of absorbed power, pressure, and flow rate to +/-1.8 W from an energy balance around the system. The percentage of power that is transferred to the gas is found to increase with increasing flow rate, decrease with increasing pressure, and to be independent of absorbed power

  12. Bluff Body Flow Control Using Dielectric Barrier Discharge Plasma Actuators

    Science.gov (United States)

    Thomas, Flint; Kozlov, Alexey

    2008-11-01

    The results of an experimental investigation involving the use of dielectric barrier discharge plasma actuators to control bluff body flow is presented. The motivation for the work is plasma landing gear noise control for commercial transport aircraft. For these flow control experiments, the cylinder in cross-flow is chosen for study since it represents a generic flow geometry that is similar in all essential aspects to a landing gear strut. The current work is aimed both at extending the plasma flow control concept to Reynolds numbers typical of landing approach and take-off and on the development of optimum plasma actuation strategies. The cylinder wake flow with and without actuation are documented in detail using particle image velocimetry (PIV) and constant temperature hot-wire anemometry. The experiments are performed over a Reynolds number range extending to ReD=10^5. Using either steady or unsteady plasma actuation, it is demonstrated that even at the highest Reynolds number Karman shedding is totally eliminated and turbulence levels in the wake decrease by more than 50%. By minimizing the unsteady flow separation from the cylinder and associated large-scale wake vorticity, the radiated aerodynamic noise is also reduced.

  13. Renal cortical and medullary blood flow responses to altered NO availability in humans.

    Science.gov (United States)

    Damkjær, Mads; Vafaee, Manoucher; Møller, Michael L; Braad, Poul Erik; Petersen, Henrik; Høilund-Carlsen, Poul Flemming; Bie, Peter

    2010-12-01

    The objective of this study was to quantify regional renal blood flow in humans. In nine young volunteers on a controlled diet, the lower abdomen was CT-scanned, and regional renal blood flow was determined by positron emission tomography (PET) scanning using H(2)(15)O as tracer. Measurements were performed at baseline, during constant intravenous infusion of nitric oxide (NO) donor glyceryl nitrate and after intravenous injection of NO synthase inhibitor N(ω)-monomethyl-L-arginine (L-NMMA). Using the CT image, the kidney pole areas were delineated as volumes of interest (VOI). In the data analysis, tissue layers with a thickness of one voxel were eliminated stepwise from the external surface of the VOI (voxel peeling), and the blood flow subsequently was determined in each new, reduced VOI. Blood flow in the shrinking VOIs decreased as the number of cycles of voxel peeling increased. After 4-5 cycles, blood flow was not reduced further by additional voxel peeling. This volume-insensitive flow was measured to be 2.30 ± 0.17 ml·g tissue(-1)·min(-1) during the control period; it increased during infusion of glyceryl nitrate to 2.97 ± 0.18 ml·g tissue(-1)·min(-1) (P blood flow was 4.67 ± 0.31 ml·g tissue(-1)·min(-1) during control, unchanged by glyceryl nitrate, and decreased after L-NMMA [3.48 ± 0.23 ml·(g·min)(-1), P renal medullary region in which the measured blood flow is 1) low, 2) independent of reduction in the VOI, and 3) reactive to changes in systemic NO supply. The technique seems to provide indices of renal medullary blood flow in humans.

  14. Marangoni flows induced by atmospheric-pressure plasma jets

    International Nuclear Information System (INIS)

    Berendsen, C W J; Van Veldhuizen, E M; Kroesen, G M W; Darhuber, A A

    2015-01-01

    We studied the interaction of atmospheric-pressure plasma jets of Ar or air with liquid films of an aliphatic hydrocarbon on moving solid substrates. The hydrodynamic jet-liquid interaction induces a track of lower film thickness. The chemical plasma-surface interaction oxidizes the liquid, leading to a local increase of the surface tension and a self-organized redistribution of the liquid film. We developed a numerical model that qualitatively reproduces the formation, instability and coarsening of the flow patterns observed in the experiments. Monitoring the liquid flow has potential as an in-situ, spatially and temporally resolved, diagnostic tool for the plasma-liquid surface interaction. (paper)

  15. Quantification of renal cortical blood flow using factor analysis of O-15 water dynamic PET images

    International Nuclear Information System (INIS)

    Seo, Kang Jun; Ahn, Ji Young; Lee, Jae Sung; Paeng, Jin Chul; Cheon, Gi Jeong; Lee, Dong Soo; Noh, Tae Won; Chung, June Key; Lee, Myung Chul

    2000-01-01

    To obtain spatial distribution of renal factor images, input function, and regional tissue time-activity curve (TAC) from O-15 water dynamic PET images non-invasively, factor analysis (FA) was used. O-15 water dynamic PET scans were performed on 3 normal dogs (22 ∼ 29 kg) with the bolus injection of O-15 water (555 ∼ 740 Mbq). We performed FA on the masked dynamic images and obtained the pure TACs and the corresponding factor images. Microsphere experiment also was performed. 37MBq of microsphere labeled with Sc-46 was injected into the left ventricle. Arterial input functions derived from the PET images using FA were compared with the invasively derived arterial blood samples. The renal cortical blood flow using the TACs by FA was within the normal range of 1.23 ∼ 2.46 ml/min/g. In microsphere study, the renal cortical blood flow of left kidney by FA was 2.49±0.47 ml/min/g (1.81∼2.90 ml/min/g) and by microsphere was 2.52 ±0.19 ml/min/g (2.34 ∼2.68 ml/min/g). In right kidney, flow by FA was 2.02 ±0.32 ml/min/g (1.82∼2.49 ml/min/g) and by microsphere was 2.49 ±0.27 ml/min/g (2.02∼2.7). FA is a useful and robust method to extract input functions and tissue TACs from O-15 dynamic renal PET. Renal cortical blood flow can be estimated non-invasively using FA and it will be helpful for the assessment of renal functional disease

  16. Renal cortical and medullary blood flow during modest saline loading in humans

    DEFF Research Database (Denmark)

    Damkjær, M; Vafaee, M; Braad, P E

    2012-01-01

    Renal medullary blood flow (RMBF) is considered an important element of sodium homeostasis, but the experimental evidence is incongruent. Studies in anaesthetized animals generally support the concept in contrast to measurements in conscious animals. We hypothesized that saline-induced natriuresis...

  17. Stationary shear flows in CGL anisotropic toroidal plasmas

    International Nuclear Information System (INIS)

    Pastukhov, V.P.; Ilgisonis, V.I.

    1996-01-01

    Recently a general structure of stationary shear flows in toroidal plasmas was obtained in the frame of ideal isotropic-pressure MHD model. The structure of the stationary plasma flows was shown to be determined by a hidden symmetry of MHD equations inherent in the toroidal systems with nested magnetic surfaces. However, the characteristic frequencies of the stationary plasma motion can considerably exceed the collisional frequencies in real plasma experiments. In this case the CGL collisionless MHD model seems to be more adequate than the simplified isotropic-pressure MHD model to describe the stationary plasma flows. In this paper we have generalized our approach to analyze the stationary plasma flows in the frame of the collisionless CGL model. We have found again that the hidden symmetry inherent in the toroidal topology results in two integral invariants which depend on two independent surface functions. The structure of stationary flows for CGL model is still the same as for isotropic MHD, however, the pressure tensor components satisfy a appreciably modifies the steady state force-balance equation. These results are applied to analyze the generalized equilibrium in axisymmetric (tokamak-like) magnetic confinement systems

  18. A study of renal blood flow regulation using the discrete wavelet transform

    Science.gov (United States)

    Pavlov, Alexey N.; Pavlova, Olga N.; Mosekilde, Erik; Sosnovtseva, Olga V.

    2010-02-01

    In this paper we provide a way to distinguish features of renal blood flow autoregulation mechanisms in normotensive and hypertensive rats based on the discrete wavelet transform. Using the variability of the wavelet coefficients we show distinctions that occur between the normal and pathological states. A reduction of this variability in hypertension is observed on the microscopic level of the blood flow in efferent arteriole of single nephrons. This reduction is probably associated with higher flexibility of healthy cardiovascular system.

  19. Albumin infusion improves renal blood flow autoregulation in patients with acute decompensation of cirrhosis and acute kidney injury.

    Science.gov (United States)

    Garcia-Martinez, Rita; Noiret, Lorette; Sen, Sambit; Mookerjee, Rajeshwar; Jalan, Rajiv

    2015-02-01

    In cirrhotic patients with renal failure, renal blood flow autoregulation curve is shifted to the right, which is consequent upon sympathetic nervous system activation and endothelial dysfunction. Albumin infusion improves renal function in cirrhosis by mechanisms that are incompletely understood. We aimed to determine the effect of albumin infusion on systemic haemodynamics, renal blood flow, renal function and endothelial function in patients with acute decompensation of cirrhosis and acute kidney injury. Twelve patients with refractory ascites and 10 patients with acute decompensation of cirrhosis and acute kidney injury were studied. Both groups were treated with intravenous albumin infusion, 40-60 g/days over 3-4 days. Cardiac and renal haemodynamics were measured. Endothelial activation/dysfunction was assessed using von Willebrand factor and serum nitrite levels. F2α Isoprostanes, resting neutrophil burst and noradrenaline levels were quantified as markers of oxidative stress, endotoxemia and sympathetic activation respectively. Albumin infusion leads to a shift in the renal blood flow autoregulation curve towards normalization, which resulted in a significant increase in renal blood flow. Accordingly, improvement of renal function was observed. In parallel, a significant decrease in sympathetic activation, inflammation/oxidative stress and endothelial activation/dysfunction was documented. Improvement of renal blood flow correlated with improvement in endothelial activation (r = 0.741, P renal function in acutely decompensated cirrhotic patients with acute kidney injury by impacting on renal blood flow autoregulation. This is possibly achieved through endothelial stabilization and a reduction in the sympathetic tone, endotoxemia and oxidative stress. © 2014 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.

  20. Sheared flow amplification by vacuum magnetic islands in stellarator plasmas

    International Nuclear Information System (INIS)

    Garcia, L.; Carreras, B. A.; Lynch, V. E.; Pedrosa, M. A.; Hidalgo, C.

    2001-01-01

    There is some experimental evidence that the E x B flows have radial structure that may be linked to rational surfaces. This flow structure may result from a self-organization process involving nonlinear flow amplification through Reynolds stress and fluctuation reduction by sheared flows. In stellarators, a large contribution to the Reynolds stress comes from the coupling of the magnetic field component of a vacuum field island with a plasma instability. In this process, the self-organization principle seems to be marginal stability for the fluctuations driving the flow

  1. Effect of toroidal plasma flow and flow shear on global MHD modes

    International Nuclear Information System (INIS)

    Chu, M.S.; Greene, J.M.; Jensen, T.H.; Miller, R.L.; Bondeson, A.; Johnson, R.W.; Mauel, M.E.

    1995-01-01

    The effect of a subsonic toroidal flow on the linear magnetohydrodynamic stability of a tokamak plasma surrounded by an external resistive wall is studied. A complex non-self-adjoint eigenvalue problem for the stability of general kink and tearing modes is formulated, solved numerically, and applied to high β tokamaks. Results indicate that toroidal plasma flow, in conjunction with dissipation in the plasma, can open a window of stability for the position of the external wall. In this window, stable plasma beta values can significantly exceed those predicted by the Troyon scaling law with no wall. Computations utilizing experimental data indicate good agreement with observations

  2. Endothelin-1 and -3 plasma concentrations in patients with cirrhosis: role of splanchnic and renal passage and liver function

    DEFF Research Database (Denmark)

    Gerbes, A L; Møller, S; Gülberg, V

    1995-01-01

    of splanchnic and renal passage and of liver function on plasma concentrations of endothelin-1 (ET-1) and endothelin-3 (ET-3) in patients with cirrhosis compared with controls. Eighteen patients with cirrhosis and 8 normotensive controls of similar age were investigated. Arterial and venous plasma samples were...

  3. Measurement of plasma flows into tile gaps

    Czech Academy of Sciences Publication Activity Database

    Dejarnac, Renaud; Komm, Michael; Stöckel, Jan; Pánek, Radomír

    2008-01-01

    Roč. 382, č. 1 (2008), s. 31-34 ISSN 0022-3115 R&D Projects: GA AV ČR KJB100430602 Institutional research plan: CEZ:AV0Z20430508 Keywords : Tokamak diagnostic * Gaps * Ion saturation current * Edge modeling * Sheaths Subject RIV: BL - Plasma and Gas Discharge Physics Impact factor: 1.501, year: 2008

  4. Plasma flow interaction with a solid target

    International Nuclear Information System (INIS)

    Karlykuanov, N.G.; Martynenko, Yu.V.; Matveenko, Yu.I.

    1996-01-01

    The physical-mathematical model of plasma interactions with a solid target wherein equations with a solid target of ion levels population and radiation transport in lines and continuum as well as kinetics of the target destruction and evaporation is presented

  5. Transport in zonal flows in analogous geophysical and plasma systems

    Science.gov (United States)

    del-Castillo-Negrete, Diego

    1999-11-01

    Zonal flows occur naturally in the oceans and the atmosphere of planets. Important examples include the zonal flows in Jupiter, the stratospheric polar jet in Antarctica, and oceanic jets like the Gulf Stream. These zonal flows create transport barriers that have a crucial influence on mixing and confinement (e.g. the ozone depletion in Antarctica). Zonal flows also give rise to long-lasting vortices (e.g. the Jupiter red spot) by shear instability. Because of this, the formation and stability of zonal flows and their role on transport have been problems of great interest in geophysical fluid dynamics. On the other hand, zonal flows have also been observed in fusion plasmas and their impact on the reduction of transport has been widely recognized. Based on the well-known analogy between Rossby waves in quasigeostrophic flows and drift waves in magnetically confined plasmas, I will discuss the relevance to fusion plasmas of models and experiments recently developed in geophysical fluid dynamics. Also, the potential application of plasma physics ideas to geophysical flows will be discussed. The role of shear in the suppression of transport and the effect of zonal flows on the statistics of transport will be studied using simplified models. It will be shown how zonal flows induce large particle displacements that can be characterized as Lévy flights, and that the trapping effect of vortices combined with the zonal flows gives rise to anomalous diffusion and Lévy (non-Gaussian) statistics. The models will be compared with laboratory experiments and with atmospheric and oceanographic qualitative observations.

  6. Analysis of interaction between TGF and the myogenic response in renal blood flow autoregulation

    DEFF Research Database (Denmark)

    Feldberg, R; Colding-Jørgensen, M; Holstein-Rathlou, N H

    1995-01-01

    . The contribution of TGF to smooth muscle activity is assumed to be a linear function of the glomerular capillary pressure. The results show that the myogenic response plays an important role in renal blood flow autoregulation. Without a myogenic response, mechanisms such as TGF that are localized in the distal......The present study investigates the interaction between the tubuloglomerular feedback (TGF) response and the myogenic mechanism by use of a mathematical model. The two control mechanisms are implemented in a spatially distributed model of the rat renal juxtamedullary afferent arteriole. The model...

  7. Jet flow and premixed jet flame control by plasma swirler

    Energy Technology Data Exchange (ETDEWEB)

    Li, Gang, E-mail: ligang@iet.cn [Key laboratory of light duty gas turbine, Institute of Engineering Thermophysics, Chinese Academy of Sciences, Beijing 100190 (China); Jiang, Xi [School of Engineering and Materials Science, Queen Mary University of London, Mile End Road, London E1 4NS (United Kingdom); Zhao, Yujun [School of Mechanism, Electronic and Control Engineering, Beijing Jiaotong University, Beijing 100044 (China); Liu, Cunxi [Key laboratory of light duty gas turbine, Institute of Engineering Thermophysics, Chinese Academy of Sciences, Beijing 100190 (China); Chen, Qi [School of Mechanism, Electronic and Control Engineering, Beijing Jiaotong University, Beijing 100044 (China); Xu, Gang; Liu, Fuqiang [Key laboratory of light duty gas turbine, Institute of Engineering Thermophysics, Chinese Academy of Sciences, Beijing 100190 (China)

    2017-04-04

    A swirler based on dielectric barrier discharge plasma actuators is designed and its effectiveness in both jet flow and premixed jet flame control is demonstrated. In contrast to traditional spanwise-oriented actuators, plasma actuators are placed along the axial direction of the injector to induce a circumferential velocity to the main flow and create a swirl flow without any insertion or moving part. In the DBD plasma swirl injector, the discharge does not ignite the mixture nor does it induce flashback. Flame visualization is obtained by cameras while velocity profiles are obtained by Laser Doppler Anemometry measurements. The results obtained indicate the effectiveness of the new design. - Highlights: • The discharge does not ignite the mixture nor does it induce flashback. • The prominent advantage of this novel plasma swirler is its swirl number adjustable without any mechanical movement. • The frequency of the plasma swirler is adjustable. • The plasma swirler can be used as an oscillator to the reactants. • The plasma swirler can be used alone or combine with other traditional swirlers.

  8. Leukocyte and platelet depletion improves blood flow and function in a renal transplant model.

    Science.gov (United States)

    Yates, Phillip J; Hosgood, Sarah A; Nicholson, Michael L

    2012-01-01

    Donation after cardiac death (DCD) donors are an important source of organs for transplantation. Due to warm and cold ischemic injury, DCD kidneys undergo a significant reperfusion insult when transplanted. This is manifested clinically as a high incidence of delayed graft function (DGF) and primary non-function (PNF). The importance of leukocytes in the generation of reperfusion injury is pivotal. Using an ex vivo porcine model of kidney transplantation, the effects of reperfusion with leukocyte and platelet depleted blood (LDB) and whole blood (WB) on renal blood flow and function were compared. Hemodynamic measurements were recorded, and biochemical, hematological, and histologic samples taken at set time-points. Reperfusion with LDB improved renal blood flow significantly compared with WB reperfusion. In addition, there was a significant improvement in creatinine clearance and renal oxygen consumption, but not fractional excretion of sodium, acid-base homeostasis, urinary nitric oxide (NO), or 8-isoprostane levels. This study represents a good model for the initial reperfusion period in renal transplantation. Improvement in only some functional markers and neither urinary NO nor 8-isoprostane levels indicates that improved blood flow alone is not sufficient to reverse the severe ischemic insult endured by DCD kidneys. Copyright © 2012 Elsevier Inc. All rights reserved.

  9. Renal effects of amino acids and dopamine in renal transplant recipients treated with or without cyclosporin A

    DEFF Research Database (Denmark)

    Hansen, J M; Olsen, Niels Vidiendal; Leyssac, P P

    1996-01-01

    1. The nephrotoxic effects of cyclosporin A may diminish the ability of the transplanted kidney to increase the glomerular filtration rate and effective renal plasma flow during infusion of dopamine or amino acids. 2. The present study included 16 renal transplant recipients transplanted for more...... and of dopamine in renal transplant recipients with a good graft function.......-creatinine, 89 +/- 6 mumol/l). The renal response to infusion of dopamine and of amino acids was investigated on two separate days. All clearance measurements were carried out at nadir cyclosporin A blood levels. 3. Effective renal plasma flow increased significantly in the non-cyclosporin A group...

  10. Clinical analysis of the changes of plasma PRA, AT-II and Aid levels in patients with acute renal failure

    International Nuclear Information System (INIS)

    Zhang Qiuyue; Yang Yongqing

    2002-01-01

    Objective: To investigate the role of changes of plasma PRA, AT-II and Ald levels in the pathogenesis of acute renal failure. Methods: Plasma PRA, AT-II and Ald levels were determined with RIA in 40 normal subjects and 72 cases of acute renal failure. Results: Plasma PRA, AT-II and Ald levels in the patients were markedly increased as compared with those in normal subjects (p < 0.05, p < 0.01, p < 0.001 respectively). There were no linearity and exponential relationship between plasma PRA, AT-II, Ald levels and the 24 h urinary sodium excretion amount (within the range of 89.1 - 365.2 mEq). Conclusion: Acute renal failure could activate the RAAS function

  11. Effect of additive renin inhibition with aliskiren on renal blood flow in patients with Chronic Heart Failure and Renal Dysfunction (Additive Renin Inhibition with Aliskiren on renal blood flow and Neurohormonal Activation in patients with Chronic Heart Failure and Renal Dysfunction).

    Science.gov (United States)

    Schroten, Nicolas F; Damman, Kevin; Hemmelder, Marc H; Voors, Adriaan A; Navis, Gerjan; Gaillard, Carlo A J M; van Veldhuisen, Dirk J; Van Gilst, Wiek H; Hillege, Hans L

    2015-05-01

    We examined the effect of the renin inhibitor, aliskiren, on renal blood flow (RBF) in patients with heart failure with reduced ejection fraction (HFREF) and decreased glomerular filtration rate (GFR). Renal blood flow is the main determinant of GFR in HFREF patients. Both reduced GFR and RBF are associated with increased mortality. Aliskiren can provide additional renin-angiotensin-aldosterone system inhibition and increases RBF in healthy individuals. Patients with left ventricular ejection fraction ≤45% and estimated GFR 30 to 75 mL/min per 1.73 m(2) on optimal medical therapy were randomized 2:1 to receive aliskiren 300 mg once daily or placebo. Renal blood flow and GFR were measured using radioactive-labeled (125)I-iothalamate and (131)I-hippuran at baseline and 26 weeks. After 41 patients were included, the trial was halted based on an interim safety analysis showing futility. Mean age was 68 ± 9 years, 82% male, GFR (49 ± 16 mL/min per 1.73 m(2)), RBF (294 ± 77 mL/min per 1.73 m(2)), and NT-proBNP 999 (435-2040) pg/mL. There was a nonsignificant change in RBF after 26 weeks in the aliskiren group compared with placebo (-7.1 ± 30 vs +14 ± 54 mL/min per 1.73 m(2); P = .16). However, GFR decreased significantly in the aliskiren group compared with placebo (-2.8 ± 6.0 vs +4.4 ± 9.6 mL/min per 1.73 m(2); P = .01) as did filtration fraction (-2.2 ± 3.3 vs +1.1 ± 3.1%; P = .01). There were no significant differences in plasma aldosterone, NT-proBNP, urinary tubular markers, or adverse events. Plasma renin activity was markedly reduced in the aliskiren group versus placebo throughout the treatment phase (P = .007). Adding aliskiren on top of optimal HFREF medical therapy did not improve RBF and was associated with a reduction of GFR and filtration fraction. Copyright © 2015 Mosby, Inc. All rights reserved.

  12. Effective renal blod flow and canalicular function of kidneys obliterating endarteritis

    International Nuclear Information System (INIS)

    Davydova, L.I.; Zajtsev, V.T.; Kononenko, E.I.; Gorbenko, L.V.; Karpovich, I.P.; Troyan, V.I.; Skripko, V.A.; Belousova, L.G.; Pavlova, T.S.

    1978-01-01

    Effective renal blood flow (general and separate) as well as the secretory-evacuatory function of the canalicular system of kidneys in 39 patients with obliterating endarteritis and in 20 persons of a control group have been studied by means of hippuran 131 I. Considerable decrease in the effective renal blood flow has been revealed. The decrease in blood flow with the increase in the ischemia degree turned out to be insignificant. The total function of kidneys is reduced in the 2-5 stages of diseases. Indices of secretory - evacuatory function of canals were changed. Indices of the total function of kidneys and intrarenal hemodynamics are the most informative when studying the state of this organ

  13. [Changes of renal blood flow during organ-associated foot reflexology measured by color Doppler sonography].

    Science.gov (United States)

    Sudmeier, I; Bodner, G; Egger, I; Mur, E; Ulmer, H; Herold, M

    1999-06-01

    Using colour Doppler sonography blood flow changes of the right kidney during foot reflexology were determined in a placebo-controlled, double-blind, randomised study. 32 healthy young adults (17 women, 15 men) were randomly assigned to the verum or placebo group. The verum group received foot reflexology at zones corresponding to the right kidney, the placebo group was treated on other foot zones. Before, during and after foot reflexology the blood flow of three vessels of the right kidney was measured using colour Doppler sonography. Systolic peak velocity and end diastolic peak velocity were measured in cm/s, and the resistive index, a parameter of the vascular resistance, was calculated. The resistive index in the verum group showed a highly significant decrease (p foot reflexology. There was no difference between men and women and no difference between smokers and non-smokers. Verum and placebo group significantly differed concerning alterations of the resistive index both between the measuring points before versus during foot reflexology (p = 0.002) and those during versus after foot reflexology (p = 0.031). The significant decrease of the resistive index during foot reflexology in the verum group indicates a decrease of flow resistance in renal vessels and an increase of renal blood flow. These findings support the hypothesis that organ-associated foot reflexology is effective in changing renal blood flow during therapy.

  14. Study of Plasma Flow Modes in Imploding Nested Arrays

    Science.gov (United States)

    Mitrofanov, K. N.; Aleksandrov, V. V.; Gritsuk, A. N.; Branitsky, A. V.; Frolov, I. N.; Grabovski, E. V.; Sasorov, P. V.; Ol'khovskaya, O. G.; Zaitsev, V. I.

    2018-02-01

    Results from experimental studies of implosion of nested wire and fiber arrays at currents of up to 4 MA at the Angara-5-1 facility are presented. Depending on the ratio between the radii of the inner and outer arrays, different modes of the plasma flow in the space between the inner and outer arrays were implemented: the sub-Alfvénic ( V r V A ) modes and a mode with the formation of the transition shock wave (SW) region between the cascades. By varying the material of the outer array (tungsten wires or kapron fibers), it is shown that the plasma flow mode between the inner and outer arrays depends on the ratio between the plasma production rates ṁ in / ṁ out in the inner and outer arrays. The obtained experimental results are compared with the results of one-dimensional MHD simulation of the plasma flow between the arrays. Stable implosion of the inner array plasma was observed in experiments with combined nested arrays consisting of a fiber outer array and a tungsten inner array. The growth rates of magnetic Rayleigh-Taylor (MRT) instability in the inner array plasma at different numbers of fibers in the outer array and different ratios between the radii of the inner and outer arrays are compared. Suppression of MRT instability during the implosion of the inner array plasma results in the formation of a stable compact Z-pinch and generation of a soft X-ray pulse. A possible scenario of interaction between the plasmas of the inner and outer arrays is offered. The stability of the inner array plasma in the stage of final compression depends on the character of interaction of plasma jets from the outer array with the magnetic field of the inner array.

  15. Laboratory simulation of energetic flows of magnetospheric planetary plasma

    International Nuclear Information System (INIS)

    Shaikhislamov, I F; Posukh, V G; Melekhov, A V; Boyarintsev, E L; Zakharov, Yu P; Prokopov, P A; Ponomarenko, A G

    2017-01-01

    Dynamic interaction of super-sonic counter-streaming plasmas moving in dipole magnetic dipole is studied in laboratory experiment. First, a quasi-stationary flow is produced by plasma gun which forms a magnetosphere around the magnetic dipole. Second, explosive plasma expanding from inner dipole region outward is launch by laser beams focused at the surface of the dipole cover. Laser plasma is energetic enough to disrupt magnetic field and to sweep through the background plasma for large distances. Probe measurements showed that far from the initially formed magnetosphere laser plasma carries within itself a magnetic field of the same direction but order of magnitude larger in value than the vacuum dipole field at considered distances. Because no compression of magnetic field at the front of laser plasma was observed, the realized interaction is different from previous experiments and theoretical models of laser plasma expansion into uniform magnetized background. It was deduced based on the obtained data that laser plasma while expanding through inner magnetosphere picks up a magnetized shell formed by background plasma and carries it for large distances beyond previously existing magnetosphere. (paper)

  16. Kelvin-Helmholtz instability in a bounded plasma flow

    International Nuclear Information System (INIS)

    Burinskaya, T. M.

    2008-01-01

    Kelvin-Helmholtz instability in a three-layer plane geometry is investigated theoretically. It is shown that, in a three-layer system (in contrast to the traditionally considered case in which instability develops at the boundary between two plasma flows), instability can develop at an arbitrary ratio of the plasma flow velocity to the ion-acoustic velocity. Perturbations with wavelengths on the order of the flow thickness or longer can increase even at a zero temperature. The system can also be unstable against long-wavelength perturbations if the flow velocity at one of the boundaries is lower than the sum of the Alfven velocities in the flow and the ambient plasma. The possibility of applying the results obtained to interpret the experimental data acquired in the framework of the CLUSTER multisatellite project is discussed. It follows from these data that, in many cases, the propagation of an accelerated particle flow in the plasma-sheet boundary layer of the Earth's magnetotail is accompanied by the generation of magnetic field oscillations propagating with a velocity on the order of the local Alfven velocity.

  17. Plasma flow measurements in a simulated low earth orbit plasma

    International Nuclear Information System (INIS)

    Gabriel, S.B.; Mccoy, J.E.; Carruth, M.R. Jr.

    1982-01-01

    The employment of large, higher power solar arrays for space operation has been considered, taking into account a utilization of high operating voltages. In connection with the consideration of such arrays, attention must be given to the fact that the ambient environment of space contains a tenuous low energy plasma which can interact with the high voltage array causing power 'leakage' and arcing. An investigation has been conducted with the aim to simulate the behavior of such an array in low-earth-orbit (LEO). During the experiments, local concentrations of the 'leakage' current were observed when the panel was at a high voltage. These concentrations could overload or damage a small area of cells in a large string. It was hypothesized that this effect was produced by electrostatic focusing of the particles by the sheath fields. To verify this experimentally, an end-effect Langmuir probe was employed. The obtained results are discussed

  18. Immediate renal imaging and renography with /sup 99m/Tc methylene diphosphonate to assess renal blood flow, excretory function, and anatomy

    International Nuclear Information System (INIS)

    Glass, E.C.; DeNardo, G.L.; Hines, H.H.

    1980-01-01

    /sup 99m/Tc methylene diphosphonate (/sup 99m/Tc MDP) was evaluated as a clinical renal imaging agent in 20 patients referred for bone scintigraphy. Sequential scintigraphy, which was started immediately after injection, yielded blood flow studies of high quality, and subsequent images accurately delineated renal anatomy and excretion in nonazotemic patients. In comparison with delayed images, early images were vastly superior in quality and demonstrated improved target-to-nontarget activity ratios (p < 0.001) and improved lesion detectability (p < 0.01). Renal imaging performed incidental to bone scintigraphy with MDP can be greatly enhanced by initiating sequential scintigraphy immediately after injection

  19. Four hour creatinine clearance is better than plasma creatinine for monitoring renal function in critically ill patients

    OpenAIRE

    Pickering, John W; Frampton, Christopher M; Walker, Robert J; Shaw, Geoffrey M; Endre, Zolt?n H

    2012-01-01

    Introduction Acute kidney injury (AKI) diagnosis is based on an increase in plasma creatinine, which is a slowly changing surrogate of decreased glomerular filtration rate. We investigated whether serial creatinine clearance, a direct measure of the glomerular filtration rate, provided more timely and accurate information on renal function than serial plasma creatinine in critically ill patients. Methods Serial plasma creatinine and 4-hour creatinine clearance were measured 12-hourly for 24 h...

  20. Flow injection analysis in inductively coupled plasma spectrometry

    International Nuclear Information System (INIS)

    Rosias, Maria F.G.G.

    1995-10-01

    The main features of flow injection analysis (FIA) as contribution to the inductively coupled plasma (Icp) spectrometry are described. A systematic review of researches using the combined FIA-Icp and the benefits of this association are presented. Flow systems were proposed to perform on-line Icp solution management for multielemental determination by atomic emission spectrometry (Icp-AES) or mass spectrometry. The inclusion of on-line ion exchangers in flow systems for matrix separation and/or analyte preconcentration are presented. Together with those applications the new advent of instruments with facilities for multielement detection on flow injection signals are described. (author). 75 refs., 19 figs

  1. Radionuclide renal dynamic and function study

    International Nuclear Information System (INIS)

    Guan Liang

    1991-01-01

    The radionuclide dynamic and function study, glomerular filtration rate (GFR) and effective renal plasma flow (ERPF) were reported in 14 cases of renal and ureteral calculi patients before and after extracorporeal shock wave lithotripsy (ESWL). In 12 cases with normal renal blood flow, within 3 months after ESWL, the GFR of shock and non-shock side decreased with different extent, while the individual ERPF had little change. In 5 cases followed up 1 year after ESWL, the individual GFR and ERPF were normal. In 2 cases of severe renal function insufficiency, there was no improvement in renal function in shock side, after 5 months and 1 year, the renal function was still at low level. Thereby it is considered that ESWL is not suitable for the renal calculi patients with severe renal function insufficiency

  2. Evaluation of blood flow in Allograft Renal Arteries anastomosed with two different techniques

    International Nuclear Information System (INIS)

    Zomorrodi, A.; Bohluli, A.; Tarzamany, M.K.

    2008-01-01

    Renal artery stenosis in renal transplantation (TRAS) is an avoidable short or long term surgical complication. The etiology is multifactorial, but faulty anastomosis is a major factor. In our transplant center, we evaluated the incidence of TRAS with the use of two different suturing techniques of the anastomosis site between allograft renal and renal and iliac arteries in two groups of renal transplant recipients, group A: 14 patients (6 males and 8 females with age 16 to 59 and mean age of 38 years) in whom allograft arteries were anastomosed with a continuous suture technique and group B: 14 patients (7 males and 7 females with age 32 to 61 and mean age of 46.6 years) in whom the allograft arteries were anastomosed with a combined suture technique (continuous and uninterrupted. Post transplantation, the velocity of blood flow in the renal and iliac arteries at the site of anastomosis was measured by color Doppler ultrasound. The ultrasonographer was blinded to the surgical technique in both study groups. The ratio of the maximum velocity of blood at the site of anastomosis to that in the iliac artery of less than 2.5 was considered as non-significant stenosis, while a ratio of more than 2.5 was considered significant stenosis. In group A there were 9 cases of non-significant stenosis in comparison to 3 cases in group B, while there were no cases of significant stenosis in group A in comparison to 3 cases in group B; the difference was not statistically significant. We conclude that there was no difference in the compared surgical techniques of anastomosis in our study groups. This suggests that other factors such as gentle handling of tissue, enough spatula, margin reversion and comparable diameter of the anastomosed vessels may be more important in the prevention of renal allograft stenosis than the type of suture technique. (author)

  3. Optimization of plasma flow parameters of the magnetoplasma compressor

    International Nuclear Information System (INIS)

    Dojcinovic, I P; Kuraica, M M; Obradovc, B M; Cvetanovic, N; Puric, J

    2007-01-01

    Optimization of the working conditions of the magnetoplasma compressor (MPC) has been performed through analysing discharge and compression plasma flow parameters in hydrogen, nitrogen and argon at different pressures. Energy conversion rate, volt-ampere curve exponent and plasma flow velocities have been studied to optimize the efficiency of energy transfer from the supply source to the plasma. It has been found that the most effective energy transfer from the supply to the plasma is in hydrogen as a working gas at 1000 Pa pressure. It was found that the accelerating regime exists for hydrogen up to 3000 Pa pressures, in nitrogen up to 2000 Pa and in argon up to 1000 Pa pressure. At higher pressures MPC in all the gases works in the decelerating regime. At pressures lower than 200 Pa, high cathode erosion is observed. MPC plasma flow parameter optimization is very important because this plasma accelerating system may be of special interest for solid surface modification and other technology applications

  4. Plasma extraction by centrifugo-pneumatically induced gating of flow

    International Nuclear Information System (INIS)

    Burger, Robert; Ducrée, Jens; Reis, Nuno; Da Fonseca, João Garcia

    2013-01-01

    We present a novel valving mechanism to implement plasma extraction from whole blood on a centrifugal microfluidic ‘lab-on-a-disc’ platform. The new scheme is based on pressure-induced deflection of a liquid membrane which gates the centrifugally driven flow through a microfluidic structure. Compared to conventional concepts such as capillary burst valves, siphons or sacrificial materials, the valving structure presented here is represented by a compact, small-footprint design which obviates the need for (local) surface functionalization or hybrid materials integration, thus significantly reducing the complexity (and hence cost) of manufacture. As a pilot study of this new centrifugal flow control element, we demonstrate here the efficient separation of metered plasma from whole blood. While the flow is stopped, blood is separated into plasma and its cellular constituents by centrifugally induced sedimentation. After completion, the flow resumes by elevating the spinning frequency, providing up to 80% of the original plasma content to an overflow chamber within a short, 2 min interval. The amount of residual cells in the plasma amounts to less than 20 cells μl −1 . (paper)

  5. The pulsatility index and the resistive index in renal arteries. Associations with long-term progression in chronic renal failure

    DEFF Research Database (Denmark)

    Petersen, L J; Petersen, J R; Talleruphuus, U

    1997-01-01

    The pulsatility index (PI) and the resistive index (RI) are used as pulsed-wave Doppler measurements of downstream renal artery resistance. PI and RI have been found to correlate with renal vascular resistance, filtration fraction and effective renal plasma flow in chronic renal failure. The aim...... of the present study was to evaluate the potential relationship between these indices and the rate of decline in renal function, as reflected by changes in different parameters of renal function in patients with chronic renal failure....

  6. Directional rf probe for measurement of conductivity of flowing plasmas

    International Nuclear Information System (INIS)

    Jayakumar, R.; Chakravarthy, D.P.; Rohatgi, V.K.

    1977-01-01

    An electrodeless immersible rf probe for measurement of plasma conductivity in the range 0.01 to 100 mho/m has been designed and fabricated. The probe, with an overall diameter of 11 mm, employs unidirectional electromagnetic field lines which reduce the inaccuracies caused by insertion of the probe in a flowing plasma. In the range studied the probe output shows a linear relationship with the conductivity of the medium. Such probes are of interest in the study of MHD and reentry plasmas

  7. Plasma flow healing of magnetic islands in stellarators

    International Nuclear Information System (INIS)

    Hegna, C. C.

    2012-01-01

    Recent experiments from the large helical device (LHD) demonstrate a correlation between the “healing” of vacuum magnetic islands in stellarators and changes in the plasma flow. A model explaining this phenomenon is developed based on self-consistent torque balance and island evolution equations. In conventional stellarators, neoclassical flow damping physics plays an important role in establishing the flow profiles. The balance of neoclassical damping and cross-field viscosity produces a radial boundary layer for the plasma rotation profile outside the separatrix of a locked magnetic island. The width of this boundary layer decreases as the plasma becomes less collisional. Associated with these flow effects are plasma currents flowing in the island region that attempt to suppress island formation. These currents are enhanced as the collisionality drops making magnetic island healing occur more readily in high temperature conventional stellarators. The analytic theory produces a critical β for healing that scales monotonically with collisionality and is in qualitative agreement with LHD observations.

  8. Activation of GLP-1 receptors on vascular smooth muscle cells reduces the autoregulatory response in afferent arterioles and increases renal blood flow

    DEFF Research Database (Denmark)

    Jensen, Elisa Pouline; Poulsen, Steen Seier; Kissow, Hannelouise

    2015-01-01

    was to localize renal GLP-1 receptors and describe GLP-1 mediated effects on the renal vasculature. We hypothesized that renal GLP-1 receptors are located in the renal microcirculation and activation of these affects renal autoregulation and increases renal blood flow. In vivo autoradiography using 125I-GLP-1......, 125I-exendin-4 (GLP-1 analog) and 125I-exendin 9-39 (GLP-1 receptor antagonist) was performed in rodents to localize specific GLP-1 receptor binding. GLP-1 mediated effects on blood pressure (BP), renal blood flow (RBF), heart rate (HR), renin secretion, urinary flow rate and Na+ and K+ excretion were...... conclude that GLP-1 receptors are located in the renal vasculature including afferent arterioles. Activation of these receptors reduces the autoregulatory response of afferent arterioles to acute pressure increases and increases renal blood flow in normotensive rats....

  9. Thomson scattering measurements from asymmetric interpenetrating plasma flows

    Energy Technology Data Exchange (ETDEWEB)

    Ross, J. S., E-mail: ross36@llnl.gov; Moody, J. D.; Fiuza, F.; Ryutov, D.; Divol, L.; Huntington, C. M.; Park, H.-S. [Lawrence Livermore National Laboratory, P.O. Box 808, Livermore, California 94551 (United States)

    2014-11-15

    Imaging Thomson scattering measurements of collective ion-acoustic fluctuations have been utilized to determine ion temperature and density from laser produced counter-streaming asymmetric flows. Two foils are heated with 8 laser beams each, 500 J per beam, at the Omega Laser facility. Measurements are made 4 mm from the foil surface using a 60 J 2ω probe laser with a 200 ps pulse length. Measuring the electron density and temperature from the electron-plasma fluctuations constrains the fit of the multi-ion species, asymmetric flows theoretical form factor for the ion feature such that the ion temperatures, ion densities, and flow velocities for each plasma flow are determined.

  10. Heat flow during sawtooth collapse in tokamak plasmas

    International Nuclear Information System (INIS)

    Hanada, Kazuaki

    1994-01-01

    Heat flow during sawtooth collapse was studied on the WT-3 tokamak by using temporal evolution of soft X-ray intensity profile in the poloidal cross section in a lower hybrid current driven plasma as well as an electron cyclotron heated plasma. Two phase in sawtooth collapses were observed. In the first phases, the hottest spot that is the peak of the soft X-ray distribution approaches the inversion surface and heat flows out through a narrow gate on the inversion surface. In the second phase, the hottest spot stays on the inversion surface, and heat flows out through the whole inversion surface. This suggests that magnetic reconnection as predicted by Kadomtsev's model occurs in the first phase, but in the second phase, a different mechanism dominates heat flow. (author)

  11. MHD equilibrium of toroidal fusion plasma with stationary flows

    International Nuclear Information System (INIS)

    Galkowski, A.

    1994-01-01

    Non-linear ideal MHD equilibria in axisymmetric system with flows are examined, both in 1st and 2nd ellipticity regions. Evidence of the bifurcation of solutions is provided and numerical solutions of several problems in a tokamak geometry are given, exhibiting bifurcation phenomena. Relaxation of plasma in the presence of zero-order flows is studied in a realistic toroidal geometry. The field aligned flow allows equilibria with finite pressure gradient but with homogeneous temperature distribution. Numerical calculations have been performed for the 1st and 2nd ellipticity regimes of the extended Grad-Shafranov-Schlueter equation. Numerical technique, alternative to the well-known Grad's ADM methods has been proposed to deal with slow adiabatic evolution of toroidal plasma with flows. The equilibrium problem with prescribed adiabatic constraints may be solved by simultaneous calculations of flux surface geometry and original profile functions. (author). 178 refs, 37 figs, 5 tabs

  12. High-NaCl intake impairs dynamic autoregulation of renal blood flow in ANG II-infused rats

    DEFF Research Database (Denmark)

    Saeed, Aso; Dibona, Gerald F; Marcussen, Niels

    2010-01-01

    The aim of this study was to investigate dynamic autoregulation of renal blood flow (RBF) in ANG II-infused rats and the influence of high-NaCl intake. Sprague-Dawley rats received ANG II (250 ng·kg(-1)·min(-1) sc) or saline vehicle (sham) for 14 days after which acute renal clearance experiments...

  13. Neuropeptide Y-enhanced diuresis and natriuresis in anaesthetized rats is independent of renal blood flow reduction

    NARCIS (Netherlands)

    Bischoff, A.; Erdbrügger, W.; Smits, J.; Michel, M. C.

    1996-01-01

    1. Neuropeptide Y (NPY) has been reported to enhance diuresis and natriuresis in anaesthetized rats although it is a potent renal vasoconstrictor in vitro in vivo in several species. Therefore, we have investigated anaesthetized rats to see whether reduction in renal blood flow (RBF) and enhancement

  14. The renal quantitative scintillation camera study for determination of renal function

    International Nuclear Information System (INIS)

    Thompson, I.M. Jr.; Boineau, F.G.; Evans, B.B.; Schlegel, J.U.

    1983-01-01

    The renal quantitative scintillation camera study assesses glomerular filtration rate and effective renal plasma flow based upon renal uptake of 99mtechnetium-iron ascorbate and 131iodine-hippuran, respectively. The method was compared to inulin, para-aminohippuric acid and creatinine clearance studies in 7 normal subjects and 9 patients with various degrees of reduced renal function. The reproducibility of the technique was determined in 15 randomly selected pediatric patients. The values of glomerular filtration rate and effective renal plasma flow were not significantly different from those of inulin and para-aminohippuric acid studies. The reproducibility of the technique was comparable to that of inulin and para-aminohippuric acid studies. Patient acceptance of the technique is excellent and the cost is minimal. Renal morphology and excretory dynamics also are demonstrated. The technique is advocated as a clinical measure of renal function

  15. Oscillations and chaos in renal blood flow control

    DEFF Research Database (Denmark)

    Holstein-Rathlou, N H

    1993-01-01

    In normotensive, halothane-anesthetized rats, oscillations can be found both in the single-nephron blood flow and in the tubular pressure. Experimental data and computer simulations support the hypothesis that the oscillations are caused by the tubuloglomerular feedback (TGF) mechanism. Model...... oscillations. The parameter range where model studies show instability overlaps with the physiologic range for the values of the same parameters. The system appears to be poised on the border between stability and oscillation, and a small parameter change may cause the system to move from one state...

  16. Measurement of renal blood flow by phase-contrast magnetic resonance imaging during septic acute kidney injury: a pilot investigation.

    Science.gov (United States)

    Prowle, John R; Molan, Maurice P; Hornsey, Emma; Bellomo, Rinaldo

    2012-06-01

    In septic patients, decreased renal perfusion is considered to play a major role in the pathogenesis of acute kidney injury. However, the accurate measurement of renal blood flow in such patients is problematic and invasive. We sought to overcome such obstacles by measuring renal blood flow in septic patients with acute kidney injury using cine phase-contrast magnetic resonance imaging. Pilot observational study. University-affiliated general adult intensive care unit. Ten adult patients with established septic acute kidney injury and 11 normal volunteers. Cine phase-contrast magnetic resonance imaging measurement of renal blood flow and cardiac output. The median age of the study patients was 62.5 yrs and eight were male. At the time of magnetic resonance imaging, eight patients were mechanically ventilated, nine were on continuous hemofiltration, and five required vasopressors. Cine phase-contrast magnetic resonance imaging examinations were carried out without complication. Median renal blood flow was 482 mL/min (range 335-1137) in septic acute kidney injury and 1260 mL/min (range 791-1750) in healthy controls (p = .003). Renal blood flow indexed to body surface area was 244 mL/min/m2 (range 165-662) in septic acute kidney injury and 525 mL/min/m2 (range 438-869) in controls (p = .004). In patients with septic acute kidney injury, median cardiac index was 3.5 L/min/m2 (range 1.6-8.7), and median renal fraction of cardiac output was only 7.1% (range 4.4-10.8). There was no rank correlation between renal blood flow index and creatinine clearance in patients with septic acute kidney injury (r = .26, p = .45). Cine phase-contrast magnetic resonance imaging can be used to noninvasively and safely assess renal perfusion during critical illness in man. Near-simultaneous accurate measurement of cardiac output enables organ blood flow to be assessed in the context of the global circulation. Renal blood flow seems consistently reduced as a fraction of cardiac output in

  17. Intravenous digital subtraction angiography for the evaluation of renal artery blood flow following the removal of a neuroblastoma

    International Nuclear Information System (INIS)

    Yamagiwa, Iwao; Obata, Kazuya; Saito, Hiroyuki; Washio, Masahiko

    1994-01-01

    There have been several reports of acute renal failure following the resection of an abdominal neuroblastoma combined with ipsilateral nephrectomy as well as the atrophy or disappearance of an unresected kidney after tumor resection. Spasms or thrombosis of the renal artery during tumor excision are considered to be the major cause. Since 1989, intravenous digital subtraction angiography (IVDSA) has been used to evaluate the renal artery blood flow immediately following surgery in seven patients with abdominal neuroblastomas. IVDSA was performed using a central venous catheter inserted prior to surgery. In all seven patients, IVDSA provided clear images for the evaluation of renal artery blood flow. In one of the two patients whose kidneys briefly became cyanosed during tumor excision, IVDSA demonstrated an occlusion of the renal artery and prompt measures could be taken to reestablish the blood flow. No complications of IVDSA occurred in any of the seven patients. IVDSA using a central venous catheter was thus considered to be useful for evaluating the renal artery blood flow in patients with a suspected renal artery blood flow disturbance without any risk of complications, and this modality obviated the need for intraarterial angiography. (author)

  18. Modelling of flow stabilization by the swirl of a peripheral flow as applied to plasma reactors

    International Nuclear Information System (INIS)

    Volchkov, E.P.; Lebedev, V.P.; Terekhov, V.I.; Shishkin, N.E.

    2000-01-01

    The gas-swirl stabilization of plasma jets is one of effective methods of its retention in the near-axial area of channels in generators of low-temperature plasma. Except the effect of gas-dynamic compression, the peripheral swirl allows to solve another urgent problem - to protect the reactor walls from the heat influence of the plasma jet. Swirl flows are also used for the flow structure formation and control of the heat and gas-dynamic characteristics of different power devices and apparatuses, using high-temperature working media: in swirl furnaces and burners, in aviation engines, etc. Investigations show that during swirl stabilization the gas-dynamic structure of the flow influences significantly the spatial stability of the plasma column and its characteristics

  19. Role of nitric oxide and prostaglandin in the maintenance of cortical and renal medullary blood flow

    Directory of Open Access Journals (Sweden)

    S.I Gomez

    2008-02-01

    Full Text Available This study was undertaken in anesthetized dogs to evaluate the relative participation of prostaglandins (PGs and nitric oxide (NO in the maintenance of total renal blood flow (TRBF, and renal medullary blood flow (RMBF. It was hypothesized that the inhibition of NO should impair cortical and medullary circulation because of the synthesis of this compound in the endothelial cells of these two territories. In contrast, under normal conditions of perfusion pressure PG synthesis is confined to the renal medulla. Hence PG inhibition should predominantly impair the medullary circulation. The initial administration of 25 µM kg-1 min-1 NG-nitro-L-arginine methyl ester produced a significant 26% decrease in TRBF and a concomitant 34% fall in RMBF, while the subsequent inhibition of PGs with 5 mg/kg meclofenamate further reduced TRBF by 33% and RMBF by 89%. In contrast, the initial administration of meclofenamate failed to change TRBF, while decreasing RMBF by 49%. The subsequent blockade of NO decreased TRBF by 35% without further altering RMBF. These results indicate that initial PG synthesis inhibition predominantly alters the medullary circulation, whereas NO inhibition decreases both cortical and medullary flow. This latter change induced by NO renders cortical and RMBF susceptible to a further decrease by PG inhibition. However, the decrease in medullary circulation produced by NO inhibition is not further enhanced by subsequent PG inhibition.

  20. Elevation of plasma milrinone concentrations in stage D heart failure associated with renal dysfunction.

    Science.gov (United States)

    Cox, Zachary L; Calcutt, Marion W; Morrison, Thomas B; Akers, Wendell S; Davis, Mary Beth; Lenihan, Daniel J

    2013-09-01

    To determine steady state milrinone concentrations in patients with stage D heart failure (HF) with and without renal dysfunction We retrospectively identified patients with stage D HF at a single medical center on continuous milrinonein fusion at the time of plasma collection for entry into a research registry database. Milrinone was prescribed and titrated to improve hemodynamic and clinical status by a cardiologist. Plasma samples were obtained at steady state milrinone concentrations. Patients were stratified by creatinine clearance (CrCl) into 4 groups: group 1 (CrCl >60 mL/min), group 2 (CrCl 60-30 mL/min), group 3 (CrCl milrinone hemodynamic changes by cardiac catheterization and electrophysiologic changes by implantable cardiac defibrillator (ICD) interrogation. A total of 29 patients were identified: group 1 (n=14), group 2 (n=10), group 3(n=3), and group 4 (n = 2). The mean infusion rate (0.391+0.08 mg/kg/min) did not differ between groups (P=0.14). The mean milrinone concentration was 451+243 ng/mL in group 1, 591+293 ng/mL in group 2, 1575+962 ng/mL in group 3, and 6252+4409 ng/mL in group 4 (Pmilrinone hemodynamic improvements between the groups (P=0.41). The ICD interrogation revealed limited comparisons, but 6 of the 8 post milrinone ventricular tachycardia episodes requiring defibrillation occurred in group 4 patients. Patients with stage D HF having severe renal dysfunction have elevated milrinone concentrations. Future studies of milrinone concentrations are warranted to investigate the potential risk of life-threatening arrhythmias and potential dosing regimens in renal dysfunction.

  1. Regional blood flows in the established stage of reduced renal mass (RRM) hypertension in rats

    International Nuclear Information System (INIS)

    Smits, G.J.; Lombard, J.H.

    1986-01-01

    Regional blood flows were measured with 15 μm 153 Gd-labelled microspheres in 21 anesthetized (pentobarbital-50 mg/kg, i.p.) male Sprague Dawley rats 5-6 weeks after a 75% reduction in renal mass and in 6 sham operated controls (SOC). RRM rats were maintained on either a high salt (HS-RRM) diet, i.e., choice of 1% NaCl or tap water (n = 11), or on a salt-restricted (SR-RRM) diet (n = 10). Mean arterial blood pressure was significantly elevated (mean +/- SE) in the HS-RRM (168 +/- 5 mmHg) vs. either the SR-RRM (147 +/- 6 mmHg) or the SOC (138 +/- 4 mmHg). Although blood flow to the skin and femur were elevated in HS-RRM and SR-RRM relative to SOC, there were no significant differences in blood flow to skeletal muscle, spleen, liver, small intestine, stomach or testes between any of the groups. Absolute renal blood flow and renal blood flow/gm of tissue were significantly lower in HS-RRM (7.2 +/- 0.7 ml/min or 3.4 +/- 0.5 ml/min/gm) and SR-RRM (6.3 +/- 0.6 ml/min or 3.2 +/- 0.3 ml/min/gm) than in SOC (15.1 +/- 0.97 ml/min or 5.5 +/- 0.2 ml/min/gm). The present results suggest that regional blood flow is unchanged in most vascular beds during the established stage of RRM hypertension in rats

  2. Renal Function in Hypothyroidism

    International Nuclear Information System (INIS)

    Khalid, S.; Khalid, M; Elfaki, M.; Hassan, N.; Suliman, S.M.

    2007-01-01

    Background Hypothyroidism induces significant changes in the function of organ systems such as the heart, muscles and brain. Renal function is also influenced by thyroid status. Physiological effects include changes in water and electrolyte metabolism, notably hyponatremia, and reliable alterations of renal hemodynamics, including decrements in renal blood flow, renal plasma flow, glomerular filtration rate (GFR). Objective Renal function is profoundly influenced by thyroid status; the purpose of the present study was to determine the relationship between renal function and thyroid status of patients with hypothyroidism. Design and Patients In 5 patients with primary hypothyroidism and control group renal functions are measured by serum creatinine and glomerular filtration rate (GFR) using modified in diet renal disease (MDRD) formula. Result In hypothyroidism, mean serum creatinine increased and mean estimated GFR decreased, compared to the control group mean serum creatinine decreased and mean estimated GFR Increased. The hypothyroid patients showed elevated serum creatinine levels (> 1.1mg/dl) compared to control group (p value .000). In patients mean estimated GFR decreased, compared to mean estimated GFR increased in the control group (p value= .002).

  3. Renal Function in Hypothyroidism

    International Nuclear Information System (INIS)

    Khalid, A. S; Ahmed, M.I; Elfaki, H.M; Hassan, N.; Suliman, S. M.

    2006-12-01

    Background hypothyroidism induces significant changes in the function of organ systems such as the heart, muscles and brain. Renal function is also influenced by thyroid status. Physiological effects include changes in water and electrolyte metabolism, notably hyponatraemia, and reliable alterations of renal hemodynamics, including decrements in renal blood flow, renal plasma flow, glomerular filtration rate (GFR). Objective renal function is profoundly influenced by thyroid status, the purpose of the present study was to determine the relationship between renal function and thyroid status of patients with hypothyroidism. Design and patients in 5 patients with primary hypothyroidism and control group renal functions are measured by serum creatinine and glomerular filtration rate(GFR) using modified in diet renal disease (MDRD) formula. Result in hypothyroidism, mean serum creatinine increased and mean estimated GFR decreased, compared to the control group mean serum creatinine decreased and mean estimated GFR increased. The hypothyroid patients showed elevated serum creatinine levels(>1.1 mg/d1) compared to control group (p value= 000). In patients mean estimated GFR increased in the control group (p value=.002).Conclusion thus the kidney, in addition to the brain, heart and muscle, is an important target of the action of thyroid hormones.(Author)

  4. The manipulation of an unstarting supersonic flow by plasma actuator

    International Nuclear Information System (INIS)

    Im, S; Cappelli, M A; Do, H

    2012-01-01

    The manipulation of an unstarting supersonic flow is demonstrated using a dielectric barrier discharge (DBD). Experiments are carried out in a Mach 4.7 model inlet flow. Flow features, such as boundary layers and shockwaves at low freestream static pressure (1 kPa) and temperature (60 K) are visualized with Rayleigh scattering from condensed CO 2 particles. Flow unstart, initiated by mass injection, is studied for three model inlet flow configurations, distinguished by the initial conditions (untripped or tripped, plasma actuated or not) of the boundary layers. Unstart in the presence of thick, tripped boundary layers is characterized by the formation of an oblique unstart shock just upstream of a separating and propagating boundary layer. The presence of plasma actuation of this tripped boundary layer seems to arrest the boundary layer separation and leads to the formation of a quasi-stationary pseudo-shock, delaying unstart. The flow generated with DBD actuation is more characteristic of what is seen when unstart is generated in a model flow in which thin boundary layers grow naturally. Planar laser Rayleigh scattering visualizations suggest that the DBD actuation thins the tripped boundary layer over the exposed electrode region.

  5. Excitation of nonlinear wave patterns in flowing complex plasmas

    Science.gov (United States)

    Jaiswal, S.; Bandyopadhyay, P.; Sen, A.

    2018-01-01

    We describe experimental observations of nonlinear wave structures excited by a supersonic mass flow of dust particles over an electrostatic potential hill in a dusty plasma medium. The experiments have been carried out in a Π- shaped experimental (DPEx) device in which micron sized Kaolin particles are embedded in a DC glow discharge Argon plasma. An equilibrium dust cloud is formed by maintaining the pumping speed and gas flow rate and the dust flow is induced either by suddenly reducing the height of a potential hill or by suddenly reducing the gas flow rate. For a supersonic flow of the dust fluid precursor solitons are seen to propagate in the upstream direction while wake structures propagate in the downstream direction. For flow speeds with a Mach number greater than 2 the dust particles flowing over the potential hill give rise to dispersive dust acoustic shock waves. The experimental results compare favorably with model theories based on forced K-dV and K-dV Burger's equations.

  6. Transesophageal Doppler measurement of renal arterial blood flow velocities and indices in children.

    Science.gov (United States)

    Zabala, Luis; Ullah, Sana; Pierce, Carol D'Ann; Gautam, Nischal K; Schmitz, Michael L; Sachdeva, Ritu; Craychee, Judith A; Harrison, Dale; Killebrew, Pamela; Bornemeier, Renee A; Prodhan, Parthak

    2012-06-01

    Doppler-derived renal blood flow indices have been used to assess renal pathologies. However, transesophageal ultrasonography (TEE) has not been previously used to assess these renal variables in pediatric patients. In this study, we (a) assessed whether TEE allows adequate visualization of the renal parenchyma and renal artery, and (b) evaluated the concordance of TEE Doppler-derived renal blood flow measurements/indices compared with a standard transabdominal renal ultrasound (TAU) in children. This prospective cohort study enrolled 28 healthy children between the ages of 1 and 17 years without known renal dysfunction who were undergoing atrial septal defect device closure in the cardiac catheterization laboratory. TEE was used to obtain Doppler renal artery blood velocities (peak systolic velocity, end-diastolic velocity, mean diastolic velocity, resistive index, and pulsatility index), and these values were compared with measurements obtained by TAU. Concordance correlation coefficient (CCC) was used to determine clinically significant agreement between the 2 methods. The Bland-Altman plots were used to determine whether these 2 methods agree sufficiently to be used interchangeably. Statistical significance was accepted at P ≤ 0.05. Obtaining 2-dimensional images of kidney parenchyma and Doppler-derived measurements using TEE in children is feasible. There was statistically significant agreement between the 2 methods for all measurements. The CCC between the 2 imaging techniques was 0.91 for the pulsatility index and 0.66 for the resistive index. These coefficients were sensitive to outliers. When the highest and lowest data points were removed from the analysis, the CCC between the 2 imaging techniques was 0.62 for the pulsatility index and 0.50 for the resistive index. The 95% confidence interval (CI) for pulsatility index was 0.35 to 0.98 and for resistive index was 0.21 to 0.89. The Bland-Altman plots indicate good agreement between the 2 methods; for the

  7. Measurement of renal blood flow by 131I-labelled sodium iodohippurate imaging in a rat model of herpes encephalitis

    International Nuclear Information System (INIS)

    Cleator, G.M.; Klapper, P.E.; Lewis, A.G.; Sharma, H.L.; Smith, A.M.; Manchester Univ.

    1990-01-01

    Renal blood flow was assessed qualitatively over a 30 min period in a rat model of herpes encephalitis by extra-renal scintigraphic imaging following the injection of 131 I-labelled sodium iodohippurate. No significant differences were observed for renal blood flow in either kidney between (or within) infected and control groups. Our data suggest that kidney function is not compromised in this animal model of encephalitis. The results are discussed in the context of the development of a non-invasive protocol for the in vivo diagnosis of herpes encephalitis. (orig.)

  8. Plasma kinetics around a dust grain in an ion flow

    International Nuclear Information System (INIS)

    Maiorov, S.A.; Vladimirov, S.V.; Cramer, N.F.

    2000-01-01

    Full text: In a typical laboratory discharge, dust particles are negatively charged and usually levitate in the sheath or pre-sheath region under the balance of gravitational, electrostatic (due to the sheath electric field) and plasma (such as the ion drag) forces. The ion flow provides not only a direct (dragging) influence, but is also responsible for the generation of associated collective plasma processes which can strongly affect the vertical arrangement of the dust grains. The complete problem of the plasma dynamics around a macroscopic body in the presence of plasma flows is highly nonlinear and therefore its numerical analysis is of major importance. Among various numerical methods, direct integration of the equations of motion of the plasma particles represents a numerical experiment whose significance approaches experiments in the laboratory. Here, we present for the first time the results of a self-consistent molecular dynamics (MD) three-dimensional (3D) simulation of the kinetics of plasma particles (electrons and ions) around a dust grain, taking into account the dust charging. The core of the method includes consideration of the time evolution of the system consisting of positively ('ions') and negatively ('electrons') charged particles confined in a simulation box together with a macroscopic absorbing grain ('dust particle') with infinite mass and an initial (negative) charge. The ions are introduced in the system as a uniform flow defined by its Mach number and the ion temperature. The paths of the ions and electrons are determined through numerical integration of the equations of motion. We demonstrate that the plasma kinetics around a dust grain in the presence of an ion flow involves a strong ion focusing behind the grain. We have also confirmed that the most important of the processes involved is the ion time-scale; the kinetics of the electrons follows a Boltzmann distribution with good agreement. We note that the time constraints involved

  9. Elevated soluble CD163 plasma levels are associated with disease severity in patients with hemorrhagic fever with renal syndrome.

    Directory of Open Access Journals (Sweden)

    Junning Wang

    Full Text Available Hantaan virus is a major zoonotic pathogen that causesing hemorrhagic fever with renal syndrome (HFRS. Although HFRS pathogenesis has not been entirely elucidated, the importance of host-related immune responses in HFRS pathogenesis has been widely recognized. CD163, a monocyte and macrophage-specific scavenger receptor that plays a vital function in the hosts can reduce inflammation, is shed during activation as soluble CD163 (sCD163. The aim of this study was to investigate the pathological significance of sCD163 in patients with HFRS.Blood samples were collected from 81 hospitalized patients in Tangdu Hospital from October 2011 to January 2014 and from 15 healthy controls. The sCD163 plasma levels were measured using a sandwich ELISA, and the relationship between sCD163 and disease severity was analyzed. Furthermore, CD163 expression in 3 monocytes subset was analyzed by flow cytometry.The results demonstrated that sCD163 plasma levels during the HFRS acute phase were significantly higher in patients than during the convalescent stage and the levels in the healthy controls (P<0.0001. The sCD163 plasma levels in the severe/critical group were higher than those in the mild/moderate group during the acute (P<0.0001. A Spearman correlation analysis indicated that the sCD163 levels were positively correlated with white blood cell, serum creatine, blood urea nitrogen levels, while they were negatively correlated with blood platelet levels in the HFRS patients. The monocyte subsets were significantly altered during the acute stage. Though the CD163 expression levels within the monocyte subsets were increased during the acute stage, the highest CD163 expression level was observed in the CD14++CD16+ monocytes when compared with the other monocyte subsets.sCD163 may be correlated with disease severity and the disease progression in HFRS patients; however, the underlying mechanisms should be explored further.

  10. Renal venogram

    Science.gov (United States)

    ... be black. Other structures will be shades of gray. Veins are not normally seen in an x- ... Venogram - kidney; Renal vein thrombosis - venogram Images Kidney anatomy Kidney - blood and urine flow Renal veins References ...

  11. Associations between plasma tenofovir concentration and renal function markers in HIV-infected women

    Directory of Open Access Journals (Sweden)

    Mwila Mulubwa

    2016-07-01

    Objective: To investigate the correlation between plasma tenofovir (TFV concentration and certain renal function markers in HIV-infected women on TDF antiretroviral therapy (ART.These markers were also compared to a HIV-uninfected control group. Methods: HIV-infected women (n = 30 on TDF-based ART were matched with 30 controls forage and body mass index. Renal markers analysed were estimated glomerular filtration rate (eGFR, creatinine clearance (CrCl, serum creatinine, albuminuria, glucosuria, serum urea, serum uric acid, urine sodium and maximum tubular reabsorption of phosphate. Baseline eGFR and CrCl data were obtained retrospectively for the HIV-infected women. Plasma TFV was assayed using a validated HPLC-MS/MS method. Step wise regression, Mann–Whitney test, unpaired and paired t-tests were applied in the statistical analyses. Results: TFV concentration was independently associated with albuminuria (adjusted r2 = 0.339; p = 0.001 in HIV-infected women. In the adjusted (weight analysis, eGFR (p = 0.038,CrCl (p = 0.032 and albuminuria (p = 0.048 were significantly higher in HIV-infected compared to the uninfected women, but eGFR was abnormally high in HIV-infected women. Both eGFR (p < 0.001 and CrCl (p = 0.008 increased from baseline to follow-up in HIV-infected women. Conclusion: Plasma TFV concentration was associated with increased albuminuria in HIV infected women in this sub-study. Both eGFR and CrCl were increased in HIV-infected women from baseline. These findings should be confirmed in larger studies, and hyperfiltration in HIV-infected women warrants further investigation.

  12. Improvement of Flow Characteristics for an Advanced Plasma Thruster

    International Nuclear Information System (INIS)

    Inutake, M.; Hosokawa, Y.; Sato, R.; Ando, A.; Tobari, H.; Hattori, K.

    2005-01-01

    A higher specific impulse and a larger thrust are required for a manned interplanetary space thruster. Until the realization of a fusion-plasma thruster, a magneto-plasma-dynamic arcjet (MPDA) powered by a fission reactor is one of the promising candidates for a manned Mars space thruster. The MPDA plasma is accelerated axially by a self-induced j x B force. Thrust performance of the MPDA is expected to increase by applying a magnetic nozzle instead of a solid nozzle. In order to get a much higher thruster performance, two methods have been investigated in the HITOP device, Tohoku University. One is to use a magnetic Laval nozzle in the vicinity of the MPDA muzzle for converting the high ion thermal energy to the axial flow energy. The other is to heat ions by use of an ICRF antenna in the divergent magnetic nozzle. It is found that by use of a small-sized Laval-type magnetic nozzle, the subsonic flow near the muzzle is converted to be supersonic through the magnetic Laval nozzle. A fast-flowing plasma is successfully heated by use of an ICRF antenna in the magnetic beach configuration

  13. Plasma equilibria and stationary flows in axisymmetric systems. Pt. 1

    International Nuclear Information System (INIS)

    Zelazny, R.; Stankiewicz, R.; Potempski, S.

    1988-05-01

    During discharges within a tokamak device such as JET fluctuations are observed in the plasma, of plasma density, temperature, electric potential and of the magnetic field. These fluctuations have complicated structure and are linked with different kinds of instabilities. However, it is not clear which instabilities are most important in determining the behaviour of the plasma. A comprehensive numerical theory which can predict the effect of the instabilities on the transport of plasma in axisymmetric systems has been sought using the static Grad-Shafranov-Schlueter (SGSS) equation as a basis. However, the static equation was over simplified for the situation in JET with additional heating giving rise to large toroidal flows, and an extended equation (EGSS) was developed. The results of the study include the discovery of algebraic branches of solutions to the EGSS equation even for very small poloidal flows, solutions to the inverse problem for the SGSS and EGSS equations using Fourier decomposition, classification of the boundary condition at the magnetic axis, demonstration of a visible effect of the poloidal flow on the separation of the density surface and the magnetic surface an indication of the existence of multiple branches of solutions to the EGSS and SGSS equations and their relation to stability properties. (U.K.)

  14. A note on supersonic flow control with nanosecond plasma actuator

    Science.gov (United States)

    Zheng, J. G.; Cui, Y. D.; Li, J.; Khoo, B. C.

    2018-04-01

    A concept study on supersonic flow control using nanosecond pulsed plasma actuator is conducted by means of numerical simulation. The nanosecond plasma discharge is characterized by the generation of a micro-shock wave in ambient air and a residual heat in the discharge volume arising from the rapid heating of near-surface gas by the quick discharge. The residual heat has been found to be essential for the flow separation control over aerodynamic bodies like airfoil and backward-facing step. In this study, novel experiment is designed to utilize the other flow feature from discharge, i.e., instant shock wave, to control supersonic flow through shock-shock interaction. Both bow shock in front of a blunt body and attached shock anchored at the tip of supersonic projectile are manipulated via the discharged-induced shock wave in an appropriate manner. It is observed that drag on the blunt body is reduced appreciably. Meanwhile, a lateral force on sharp-edged projectile is produced, which can steer the body and give it an effective angle of attack. This opens a promising possibility for extending the applicability of this flow control technique in supersonic flow regime.

  15. Relative Renal Blood Flow Measurements With Rb-82 and a Hybrid Gamma Camera Using a Pig Model

    Science.gov (United States)

    Pretorius, P. H.; Fung, L. C. T.; Schell, C. P.; King, M. A.

    2005-02-01

    We have successfully demonstrated with chronically implanted blood flow probes in a pig model that renal uptake of Rb-82 is indeed sensitive to acute renal blood flow changes. Two flow probes were placed around the left and right renal arteries in a surgical procedure nine weeks before the first Rb-82 measurements. Together with the flow probes, a flow restrictor was implanted around the left renal artery. Single bolus infusions of 6 mCi Rb-82 were used to study the uptake in the kidneys approximately 7 minutes apart in hybrid-image limited-angle acquisitions (stationary camera heads posterior and anterior of the pig) while changing the flow to the left kidney between acquisitions. The acquired data were reconstructed into 7.5-s frames using a maximum likelihood (ML) list-mode reconstruction algorithm exploiting timing signals inserted into the list every 0.25 s. Reconstructed data were orientated to coronal views before regions of interest (ROIs) were drawn over both kidneys with a separate background region for each. The data represented are noisy due to the reconstructed 7.5-s frames, and the total imaging time of 5 min (or 4 Rb-82 half-lives). We were able to show a steady decline in uptake of Rb-82 in the left kidney that correlates with the reduction in renal blood flow. The reduced blood flow to the left kidney affects the Rb-82 uptake to the right kidney slightly, while blood flow decreased up to 33%. Comparing the baseline renal blood flow of the left kidney obtained before and after the intervention indicates that some ischemia persists after blood flow was restored. Attenuation compensation better described the contour of the kidney but only scales the time activity curve without changing its shape.

  16. Analysis of IBW-driven plasma flows in tokamaks

    International Nuclear Information System (INIS)

    Berry, L.A.; Jaeger, E.F.; D'Azevedo, E.F.; Batchelor, D.B.; Carlsson, J.A.; Carter, M.D.; Cesario, R.

    2001-01-01

    Both theory and experiment have suggested that damping of Ion Bernstein Waves (IBWs) at ion cyclotron frequency harmonics could drive poloidal flows and lead to enhanced confinement for tokamaks. However, the early analyses were based on Reynolds stress closures of moment equations. More rigorous, finite Larmor radius (FLR) expansions of the radio frequency (RF) kinetic pressure for low harmonic interactions indicated that the Reynolds stress approximation was not generally valid, and resulted in significant changes in the plasma flow response. These changes were largest for wave interactions driven by finite Larmour radius effects. To provide a better assessment of higher harmonic interactions and IBW flow drive prospects, the electromagnetic (E and M) and RF kinetic force models are extended with no assumptions regarding the smallness of the ion Larmor radius. For both models, a spectral-width approximation was used to make the numerical analysis tractable. In addition, it was necessary to include the effects of plasma equilibrium gradients on the plasma conductivity and the RF-induced momentum in order to conserve energy and momentum. The analysis of high-harmonic IBW interactions for TFTR and FTU parameters indicates significant poloidal flow shears (relative to turbulence correlation times) for power levels available in present experiments. Recent advances in all-orders calculations of E and M fields in 2-D are also discussed. (author)

  17. On the geometry of field lines in plasma flows

    International Nuclear Information System (INIS)

    Bagewadi, C.S.; Prasanna Kumar, K.N.

    1988-01-01

    Many research investigators have applied differential geometry to plasma. Intrinsic properties of fluid flows in streamline, vortex line geometries are we ll known under certain set of geometric conditions. Though this approach has yielded some interesting results but the most general properties of flows can be obtained, using eight geometric parameters ksub(s), tsub(s) θsub(ns), θsub(bs), phisub(s), Ωsub(s), div n, div b and the basic necessary conditions to be satisfied by the flow in general anholonomic co-ordinate system together with the conditions to be satisfied by the geometric parameters of triply orthogonal spatial curves of congruences. Adopting the above techniques for triply orthogonal spatial curves of congruences related to the lines of forces, Purushottam has studied the geometric properties of spatial hydromagnetic fluid flows. Again these results have been studied by him in general along the field lines. These results have been studied for plasma along field lines and the basic equations of plasma have been expressed in intrinsic decomposition forms. Furthe r complex lamellar magnetic field have been studied by introducing Lie surface. (a uthor)

  18. Spontaneous electromagnetic emission from a strongly localized plasma flow.

    Science.gov (United States)

    Tejero, E M; Amatucci, W E; Ganguli, G; Cothran, C D; Crabtree, C; Thomas, E

    2011-05-06

    Laboratory observations of electromagnetic ion-cyclotron waves generated by a localized transverse dc electric field are reported. Experiments indicate that these waves result from a strong E×B flow inhomogeneity in a mildly collisional plasma with subcritical magnetic field-aligned current. The wave amplitude scales with the magnitude of the applied radial dc electric field. The electromagnetic signatures become stronger with increasing plasma β, and the radial extent of the power is larger than that of the electrostatic counterpart. Near-Earth space weather implications of the results are discussed.

  19. Exercise training attenuates chemoreflex-mediated reductions of renal blood flow in heart failure.

    Science.gov (United States)

    Marcus, Noah J; Pügge, Carolin; Mediratta, Jai; Schiller, Alicia M; Del Rio, Rodrigo; Zucker, Irving H; Schultz, Harold D

    2015-07-15

    In chronic heart failure (CHF), carotid body chemoreceptor (CBC) activity is increased and contributes to increased tonic and hypoxia-evoked elevation in renal sympathetic nerve activity (RSNA). Elevated RSNA and reduced renal perfusion may contribute to development of the cardio-renal syndrome in CHF. Exercise training (EXT) has been shown to abrogate CBC-mediated increases in RSNA in experimental heart failure; however, the effect of EXT on CBC control of renal blood flow (RBF) is undetermined. We hypothesized that CBCs contribute to tonic reductions in RBF in CHF, that stimulation of the CBC with hypoxia would result in exaggerated reductions in RBF, and that these responses would be attenuated with EXT. RBF was measured in CHF-sedentary (SED), CHF-EXT, CHF-carotid body denervation (CBD), and CHF-renal denervation (RDNX) groups. We measured RBF at rest and in response to hypoxia (FiO2 10%). All animals exhibited similar reductions in ejection fraction and fractional shortening as well as increases in ventricular systolic and diastolic volumes. Resting RBF was lower in CHF-SED (29 ± 2 ml/min) than in CHF-EXT animals (46 ± 2 ml/min, P < 0.05) or in CHF-CBD animals (42 ± 6 ml/min, P < 0.05). In CHF-SED, RBF decreased during hypoxia, and this was prevented in CHF-EXT animals. Both CBD and RDNX abolished the RBF response to hypoxia in CHF. Mean arterial pressure increased in response to hypoxia in CHF-SED, but was prevented by EXT, CBD, and RDNX. EXT is effective in attenuating chemoreflex-mediated tonic and hypoxia-evoked reductions in RBF in CHF. Copyright © 2015 the American Physiological Society.

  20. Blood pressure-renal blood flow relationships in conscious angiotensin II- and phenylephrine-infused rats.

    Science.gov (United States)

    Polichnowski, Aaron J; Griffin, Karen A; Long, Jianrui; Williamson, Geoffrey A; Bidani, Anil K

    2013-10-01

    Chronic ANG II infusion in rodents is widely used as an experimental model of hypertension, yet very limited data are available describing the resulting blood pressure-renal blood flow (BP-RBF) relationships in conscious rats. Accordingly, male Sprague-Dawley rats (n = 19) were instrumented for chronic measurements of BP (radiotelemetry) and RBF (Transonic Systems, Ithaca, NY). One week later, two or three separate 2-h recordings of BP and RBF were obtained in conscious rats at 24-h intervals, in addition to separate 24-h BP recordings. Rats were then administered either ANG II (n = 11, 125 ng·kg(-1)·min(-1)) or phenylephrine (PE; n = 8, 50 mg·kg(-1)·day(-1)) as a control, ANG II-independent, pressor agent. Three days later the BP-RBF and 24-h BP recordings were repeated over several days. Despite similar increases in BP, PE led to significantly greater BP lability at the heart beat and very low frequency bandwidths. Conversely, ANG II, but not PE, caused significant renal vasoconstriction (a 62% increase in renal vascular resistance and a 21% decrease in RBF) and increased variability in BP-RBF relationships. Transfer function analysis of BP (input) and RBF (output) were consistent with a significant potentiation of the renal myogenic mechanism during ANG II administration, likely contributing, in part, to the exaggerated reductions in RBF during periods of BP elevations. We conclude that relatively equipressor doses of ANG II and PE lead to greatly different ambient BP profiles and effects on the renal vasculature when assessed in conscious rats. These data may have important implications regarding the pathogenesis of hypertension-induced injury in these models of hypertension.

  1. Comparison of CT scan and colour flow doppler ultrasound in detecting venous tumour thrombous in renal cell carcinoma

    International Nuclear Information System (INIS)

    Khan, A.R.; Anwar, K.

    2008-01-01

    Renal cell carcinoma has marked tendency to spread into renal vein, inferior vena cava and right side of heart. Extension of tumour thrombus into these veins will alter the surgical approach. We have compared the CT scan with Colour flow Doppler ultrasound in detecting venous tumour thrombus in renal vein and inferior vena cava. This cross-sectional study included 30 adult patients presenting with renal tumour. Patients of either gender were included in the study. Non probability convenience sampling was used. All patients underwent colour flow Doppler ultrasound and CT scan with contrast to asses the renal vein and inferior vena cava. The results were confirmed by intra operative findings and histopathology. The data was analyzed using SPSS version 12. Out of 30 patients, 20 (66%) were males and 10 (34%) female. The tumour was predominantly on the right side (60%), as was renal venous tumour thrombus (44%). Inferior vena cava was involved in 4 cases predominantly due to right sided tumours. The sensitivity of Doppler ultrasound in detecting renal venous tumour thrombus (88% on right and 100% on left side) was higher than CT scan (63% on right and 60% on left side). Doppler ultrasound was also superior to CT scan in detecting vena caval thrombus. The overall sensitivity of Doppler sonography was higher than CT scan in detecting tumour extension into renal veins and inferior vena cava. Therefore, it can be used as a complementary tool in equivocal cases. (author)

  2. QUICK-FIRE: Plasma flow driven implosion experiments

    International Nuclear Information System (INIS)

    Baker, W.L.; Bigelow, W.S.; Degnan, J.H.

    1985-01-01

    High speed plasma implosions involving megajoules of energy, and sub-microsecond implosion times are expected to require additional stages of power conditioning between realistic primary energy sources and the implosion system. Plasma flow switches and vacuum inductive stores represent attractive alternates to the high speed fuse and atmospheric store techniques which have been previously reported for powering such plasma experiments. In experiments being conducted at the Air Force Weapons Lab, a washer shaped plasma accelerated to 7-10 cm/microsecond in a coaxial plasma gun configuration, represents the moving element in a vacuum store/power conditioning system of 16.5 nH inductance which stores 1-1.5 MJ at 12-14 MA. At the end of the coaxial gun, the moving element transits the 2cm axial length of the cylindrical implosion gap in 200-400 nS, delivering the magnetic energy to the implosion foil, accelerating the imploding plasma to speeds of 30-40 cm/microsecond in 350-450 nS, and delivering a projected 400 KJ of kinetic energy to the implosion

  3. Sympathetic nerve-derived ATP regulates renal medullary blood flow via vasa recta pericytes

    Directory of Open Access Journals (Sweden)

    Scott S Wildman

    2013-10-01

    Full Text Available Pericyte cells are now known to be a novel locus of blood flow control, being able to regulate capillary diameter via their unique morphology and expression of contractile proteins. We have previously shown that exogenous ATP causes constriction of vasa recta via renal pericytes, acting at a variety of membrane bound P2 receptors on descending vasa recta, and therefore may be able to regulate medullary blood flow (MBF. Regulation of MBF is essential for appropriate urine concentration and providing essential oxygen and nutrients to this region of high, and variable, metabolic demand. Various sources of endogenous ATP have been proposed, including from epithelial, endothelial and red blood cells in response to stimuli such as mechanical stimulation, local acidosis, hypoxia, and exposure to various hormones. Extensive sympathetic innervation of the nephron has previously been shown, however the innervation reported has focused around the proximal and distal tubules, and ascending loop of Henle. We hypothesise that sympathetic nerves are an additional source of ATP acting at renal pericytes and therefore regulate MBF. Using a rat live kidney slice model in combination with video imaging and confocal microscopy techniques we firstly show sympathetic nerves in close proximity to vasa recta pericytes in both the outer and inner medulla. Secondly, we demonstrate pharmacological stimulation of sympathetic nerves in situ (by tyramine evokes pericyte-mediated vasoconstriction of vasa recta capillaries; inhibited by the application of the P2 receptor antagonist suramin. Lastly, tyramine-evoked vasoconstriction of vasa recta by pericytes is significantly less than ATP-evoked vasoconstriction. Sympathetic innervation may provide an additional level of functional regulation in the renal medulla that is highly localized. It now needs to be determined under which physiological/pathophysiological circumstances that sympathetic innervation of renal pericytes is

  4. Plasma proteomics classifiers improve risk prediction for renal disease in patients with hypertension or type 2 diabetes

    NARCIS (Netherlands)

    Pena, Michelle J.; Jankowski, Joachim; Heinze, Georg; Kohl, Maria; Heinzel, Andreas; Bakker, Stephan J. L.; Gansevoort, Ron T.; Rossing, Peter; de Zeeuw, Dick; Heerspink, Hiddo J. Lambers; Jankowski, Vera

    2015-01-01

    OBJECTIVE: Micro and macroalbuminuria are strong risk factors for progression of nephropathy in patients with hypertension or type 2 diabetes. Early detection of progression to micro and macroalbuminuria may facilitate prevention and treatment of renal diseases. We aimed to develop plasma proteomics

  5. Ion flow ripples in the Earth's plasma sheet

    Science.gov (United States)

    De Spiegeleer, Alexandre; Hamrin, Maria; Pitkänen, Timo; Norqvist, Patrik; Mann, Ingrid

    2016-04-01

    For a long time, magnetotail flows were considered rather smooth and laminar, and primarily dominated by a simple convection flow pattern. However, in the early 90's, high speed bursty bulk flows (BBFs) were discovered and found to commonly perturb the underlying convection flows. In addition, there are other disturbances complicating the magnetotail flow pattern. Instabilities such as the Kelvin-Helmholz instability and the kink instability can cause different types of magnetic field oscillations, such as field line resonances. It is expected that ions will follow these oscillations if the typical time and length scales are larger than the gyroperiod and gyroradius of the ions. Though low-velocity sloshing and ripple disturbances of the average magnetotail convection flows have been observed, their connection with magnetic field oscillations is not fully understood. Furthermore, when studying BFFs, these "Ion Flow Ripples" (IFRs) are often neglected, dismissed as noise or can even erroneously be identified as BBFs. It is therefore of utter importance to find out and understand the role of IFRs in magnetotail dynamics. In a statistical investigation, we use several years of Cluster plasma sheet data to study the low-speed flows in the magnetotail. We investigate different types of IFRs, study their occurrence, and discuss their possible causes.

  6. Plasma-Assisted Chemistry in High-Speed Flow

    International Nuclear Information System (INIS)

    Leonov, Sergey B.; Yarantsev, Dmitry A.; Napartovich, Anatoly P.; Kochetov, Igor V.

    2007-01-01

    Fundamental problems related to the high-speed combustion are analyzed. The result of plasma-chemical modeling is presented as a motivation of experimental activity. Numerical simulations of the effect of uniform non-equilibrium discharge on the premixed hydrogen and ethylene-air mixture in supersonic flow demonstrate an advantage of such a technique over a heating. Experimental results on multi-electrode non-uniform discharge maintenance behind wallstep and in cavity of supersonic flow are presented. The model test on hydrogen and ethylene ignition is demonstrated at direct fuel injection to low-temperature high-speed airflow

  7. An analytic model for flow reversal in divertor plasmas

    International Nuclear Information System (INIS)

    Cooke, P.I.H.; Prinja, A.K.

    1987-04-01

    An analytic model is developed and used to study the phenomenon of flow reversal which is observed in two-dimensional simulations of divertor plasmas. The effect is shown to be caused by the radial spread of neutral particles emitted from the divertor target which can lead to a strong peaking of the ionization source at certain radial locations. The results indicate that flow reversal over a portion of the width of the scrape-off layer is inevitable in high recycling conditions. Implications for impurity transport and particle removal in reactors are discussed

  8. Plasma flow switch and foil implosion experiments on Pegasus II

    International Nuclear Information System (INIS)

    Cochrane, J.C.; Bartsch, R.R.; Benage, J.R.; Forman, P.R.; Gribble, R.F.; Ladish, J.S.; Oona, H.; Parker, J.V.; Scudder, D.W.; Shlachter, J.S.; Wysocki, F.J.

    1993-01-01

    Pegasus II is the upgraded version of Pegasus, a pulsed power machine used in the Los Alamos AGEX (Above Ground EXperiments) program. A goal of the program is to produce an intense (> 100 TW) source of soft x-rays from the thermalization of the kinetic energy of a 1 to 10 MJ plasma implosion. The radiation pulse should have a maximum duration of several 10's of nanoseconds and will be used in the study of fusion conditions and material properties. The radiating plasma source will be generated by the thermalization of the kinetic energy of an imploding cylindrical, thin, metallic foil. This paper addresses experiments done on a capacitor bank to develop a switch (plasma flow switch) to switch the bank current into the load at peak current. This allows efficient coupling of bank energy into foil kinetic energy

  9. Ion collection by probing objects in flowing magnetized plasmas

    International Nuclear Information System (INIS)

    Kyu-Sun, Chung.

    1989-04-01

    A new one-dimensional collisionless kinetic model is developed for the flow of ions to probing structures in drifting plasmas. The cross-field flow into the presheath is modelled by accounting consistently for particle exchange between the collection flux tube and the outer plasma. Numerical solutions of the self-consistent plasma/sheath equations are obtained with arbitrary external ion temperature and parallel plasma flow velocity. Results are presented of the spatial dependence of the ion distribution function as well as its moments (density, particle flux, temperature, and power flux). The ion current to the probe is obtained and the ratio of the upstream to downstream currents is found to be well represented by the form R = exp[Ku d ], where K = 1.66 for T i = T e and u d is the drift velocity in units of (T e /m i ) 1/2 . The results agree well with comparable recent fluid calculations but show substantial deviations from other models which ignore particle exchange out of the presheath. No evidence is found of the formation of shocks in the downstream wake, contrary to the implications of some fluid theories. We have also extended the previous kinetic model by generalizing cross-field transport and adding ionization to the source of the Boltzmann equation along the presheath. Ion sheath current density and ratio(R) of upstream to downstream current are obtained as a function of plasma drift velocity, equivalent viscosity, ion temperature, and ionization rate. Constants(K) in the form R = exp[Ku d ] are obtained in terms of viscosity, ion temperature, and ionization rate. The effect of an electrical bias applied to the object on the presheath characteristics is discussed

  10. Age-related features of renal function (on radiorenographic data)

    International Nuclear Information System (INIS)

    Korkushko, O.V.; Frajfel'd, V.Eh.; Belyj, A.A.

    1986-01-01

    Renal function of 91 healthy subjects aged 18-91 has been evaluated at radionuclide renography with the use of 131 I-Hippuran. Renal excretory function, effective renal plasma and blood flows were found to decrease annually by 0.09 ml/kg in ageing men and by 0.08 ml/kg in women. The use of new indices may be useful for evaluation of renal blood circulation, especially during hypo- or hypervolaemia is proposed. These are the index of renal circulation efficiency and the mean time of circulating blood volume transfer through renal blood vessels

  11. The numerical simulation of plasma flow in cylindrical resonant cavity of microwave plasma thruster

    International Nuclear Information System (INIS)

    Tang, J.-L.; He, H.-Q; Mao, G.-W.

    2004-01-01

    Microwave Plasma Thruster (MPT) is an electro-thermal propulsive device. MPT consists of microwave generator, gas storing and supplying system, resonant cavity and accelerative nozzle. It generates free-floating plasma brought by the microwave discharge breakdown gas in the resonant cavity, and the plasma exhausted from nozzle produces thrust. MPT has prospective application in spacecraft because of its advantages of high thrust, moderate specific impulse and high efficiency. In this paper, the numerical simulation of the coupling flow field of microwave plasma in resonant cavity under different frequencies will be discussed. The results of numerical simulation are as follows: 1) When the resonant model TM 011 was used, the higher the microwave frequency was, the smaller the size of MPT. The distribution of the electromagnetic field in small cavity, however, remain unchanged. 2) When the resonant model was used, the distribution of the temperature, the pressure and the electronic density in the resonant cavity remained unchanged under different resonant frequencies. 3) When the resonant frequency was increased with a fixed pressure distribution in a small cavity, compare to the MPT with lower frequency, the gas flow rate, the microwave power and the nozzle throat diameter of MPT all decreased. 4) The electromagnetic field in the cylindrical resonant cavity for all MPT with different frequencies was disturbed by the plasma formation. The strong disturbance happened in the region close to the plasma. (author)

  12. Electrical Processes in a Flowing Plasma with Cold Electrodes

    Energy Technology Data Exchange (ETDEWEB)

    Distefano, E.; Fraidenraich, N. [Facultad de Ciencias Fisicas y Matematicas, University of Chile, Santiago (Chile)

    1968-11-15

    The voltage-current characteristics of a flowing plasma between two electrodes is of interest for MHD power generation because of the high voltage drop necessary to make a current flow through the cool boundary layer of the plasma, lowering the efficiency of the MHD generator when the duct walls are cooled. The V-I characteristics are obtained for a combustion driven shock-tube generated plasma, and the voltage distribution is measured by probes inserted across the plasma. The gas used is argon and the plasma parameters are: T = 9000 Degree-Sign K, p = 130 mmHg, u = 2500 m/sec, n{sub e} = 1.60 x 10{sup 15} cm{sup -3}. The probe technique has allowed experimental confirmation of the high voltage drop obtained in the vicinity of the cathode. A theoretical model has been set up in order to explain the main features of this phenomenon. The model considers the voltage drop along the following regions: the turbulent boundary layer and the viscous sublayer. The structure of the first two regions are taken into account according to the Coles transformation theory. The model considers three fluids, ions, electrons and neutrals: the mass and momentum particle conservation together with the Poisson equation and continuity of electric current allows us to set up a system of four differential equations with four unknowns. Pair production is taken into account in order to explain the necessary change over from electron current in the main body of the plasma to the predominantly ionic current in the neighbourhood of the cathode wall. Numerical computation of the system of equations has been done and the main features of the experimental results are explained. (author)

  13. ACUTE RENAL FAILURE WITH NORMAL PLASMA UREA LEVEL SECONDARY TO ACUTE PYELONEPHITIS IN A SINGLE KIDNEY PATIENT

    Directory of Open Access Journals (Sweden)

    Imperiali N

    2006-03-01

    Full Text Available SUMMARYAcute renal failure is a syndrome that usually runs with an increase in creatinine and urea plasma levels. However, there are clinical situations in which this syndrome may run with an increase in plasma creatinine keeping normal the urea one.In this report we present a case of acute renal failure with normal plasma urea level secondary to an acute pyelonephritis in a single kidney patient. The patient had an increased fractional excretion of urea which could explain the normal plasma urea levels found despite of his reduced glomerular filtration. This increased urea excretion state was interpreted as a consequence of the nephrogenic diabetes insipidus and alteration of the intra-renal urea reciclying process that the acute pyelonephritis induced. In conclusion: Acute pyelonephritis in a single kidney patient can appear as a pattern of acute renal failure with normal plasma urea levels. RESUMEN:La insuficiencia renal aguda es un sindrome que característicamente cursa con niveles plasmáticos elevados de urea y creatinina. Sin embargo, hay situaciones clínicas en las cuales este sindrome puede cursar con un incremento de la creatininemia sin presentar elevación de la uremia.En este reporte presentamos un caso clínico de una insuficiencia renal aguda con uremia normal secundaria a una pielonefritis aguda en un paciente con riñón único. El paciente presentaba una elevada excreción fraccional de urea lo cual podía explicar su uremia normal pese a estar cursando una caída del filtrado gomerular. Dicha excreción de urea elevada fue interpretada como secundaria a una diabetes insipida nefrogénica y una alteración en el recirculado intra-renal de la urea ambos producto de la pielonefritis aguda. Concluimos que la pielonefritis aguda en un paciente mono-reno puede presentarse con un patrón de insuficiencia renal aguda con uremia normal.

  14. ACUTE RENAL FAILURE WITH NORMAL PLASMA UREA LEVEL SECONDARY TO ACUTE PYELONEPHITIS IN A SINGLE KIDNEY PATIENT

    Directory of Open Access Journals (Sweden)

    Algranati L

    2007-04-01

    Full Text Available SUMMARY: Acute renal failure is a syndrome that usually runs with an increase in creatinine and urea plasma levels. However, there are clinical situations in which this syndrome may run with an increase in plasma creatinine keeping normal the urea one. In this report we present a case of acute renal failure with normal plasma urea level secondary to an acute pyelonephritis in a single kidney patient. The patient had an increased fractional excretion of urea which could explain the normal plasma urea levels found despite of his reduced glomerular filtration. This increased urea excretion state was interpreted as a consequence of the nephrogenic diabetes insipidus and alteration of the intra-renal urea reciclying process that the acute pyelonephritis induced. In conclusion: Acute pyelonephritis in a single kidney patient can appear as a pattern of acute renal failure with normal plasma urea levels.RESUMEN: La insuficiencia renal aguda es un sindrome que característicamente cursa con niveles plasmáticos elevados de urea y creatinina. Sin embargo, hay situaciones clínicas en las cuales este sindrome puede cursar con un incremento de la creatininemia sin presentar elevación de la uremia. En este reporte presentamos un caso clínico de una insuficiencia renal aguda con uremia normal secundaria a una pielonefritis aguda en un paciente con riñón único. El paciente presentaba una elevada excreción fraccional de urea lo cual podía explicar su uremia normal pese a estar cursando una caída del filtrado gomerular. Dicha excreción de urea elevada fue interpretada como secundaria a una diabetes insipida nefrogénica y una alteración en el recirculado intra-renal de la urea ambos producto de la pielonefritis aguda. Concluimos que la pielonefritis aguda en un paciente mono-reno puede presentarse con un patrón de insuficiencia renal aguda con uremia normal.

  15. Locked magnetic island chains in toroidally flow damped tokamak plasmas

    International Nuclear Information System (INIS)

    Fitzpatrick, R; Waelbroeck, F L

    2010-01-01

    The physics of a locked magnetic island chain maintained in the pedestal of an H-mode tokamak plasma by a static, externally generated, multi-harmonic, helical magnetic perturbation is investigated. The non-resonant harmonics of the external perturbation are assumed to give rise to significant toroidal flow damping in the pedestal, in addition to the naturally occurring poloidal flow damping. Furthermore, the flow damping is assumed to be sufficiently strong to relax the pedestal ion toroidal and poloidal fluid velocities to fixed values determined by neoclassical theory. The resulting neoclassical ion flow causes a helical phase-shift to develop between the locked island chain and the resonant harmonic of the external perturbation. Furthermore, when this phase-shift exceeds a critical value, the chain unlocks from the resonant harmonic and starts to rotate, after which it decays away and is replaced by a helical current sheet. The neoclassical flow also generates an ion polarization current in the vicinity of the island chain which either increases or decreases the chain's radial width, depending on the direction of the flow. If the polarization effect is stabilizing, and exceeds a critical amplitude, then the helical island equilibrium becomes unstable, and the chain again decays away. The critical amplitude of the resonant harmonic of the external perturbation at which the island chain either unlocks or becomes unstable is calculated as a function of the pedestal ion pressure, the neoclassical poloidal and toroidal ion velocities and the poloidal and toroidal flow damping rates.

  16. Exogenous and endogenous angiotensin-II decrease renal cortical oxygen tension in conscious rats by limiting renal blood flow

    NARCIS (Netherlands)

    Emans, Tonja W.; Janssen, Ben J.; Pinkham, Maximilian I.; Ow, Connie P. C.; Evans, Roger G.; Joles, Jaap A.; Malpas, Simon C.; Krediet, C. T. Paul; Koeners, Maarten P.

    2016-01-01

    Our understanding of the mechanisms underlying the role of hypoxia in the initiation and progression of renal disease remains rudimentary. We have developed a method that allows wireless measurement of renal tissue oxygen tension in unrestrained rats. This method provides stable and continuous

  17. Daily rhythms in renal blood flow and urine production rate in the near-term sheep fetus

    NARCIS (Netherlands)

    Poortinga, FMI; Aarnoudse, JG

    Daily rhythmicity of renal blood flow (RBF) and urine flow (UF) was studied in fetal sheep between 121-125 d of gestation. Fetal arterial blood pressure, heart rate, UF, and right RBF were measured continuously for 24-h periods in 10 sheep, Rhythmic variations during a 24-h period were found for all

  18. Magnetorotational and Parker instabilities in magnetized plasma Dean flow as applied to centrifugally confined plasmas

    International Nuclear Information System (INIS)

    Huang Yimin; Hassam, A.B.

    2003-01-01

    The ideal magnetohydrodynamics stability of a Dean flow plasma supported against centrifugal forces by an axial magnetic field is studied. Only axisymmetric perturbations are allowed for simplicity. Two distinct but coupled destabilization mechanisms are present: flow shear (magnetorotational instability) and magnetic buoyancy (Parker instability). It is shown that the flow shear alone is likely insufficient to destabilize the plasma, but the magnetic buoyancy instability could occur. For a high Mach number (M S ), high Alfven Mach number (M A ) system with M S M A > or approx. πR/a (R/a is the aspect ratio), the Parker instability is unstable for long axial wavelength modes. Implications for the centrifugal confinement approach to magnetic fusion are also discussed

  19. Thermonuclear dynamo inside ultracentrifuge with supersonic plasma flow stabilization

    Energy Technology Data Exchange (ETDEWEB)

    Winterberg, F. [University of Nevada, Reno, Reno, Nevada (United States)

    2016-01-15

    Einstein's general theory of relativity implies the existence of virtual negative masses in the rotational reference frame of an ultracentrifuge with the negative mass density of the same order of magnitude as the positive mass density of a neutron star. In an ultracentrifuge, the repulsive gravitational field of this negative mass can simulate the attractive positive mass of a mini-neutron star, and for this reason can radially confine a dense thermonuclear plasma placed inside the centrifuge, very much as the positive mass of a star confines its plasma by its own attractive gravitational field. If the centrifuge is placed in an externally magnetic field to act as the seed field of a magnetohydrodynamic generator, the configuration resembles a magnetar driven by the release of energy through nuclear fusion, accelerating the plasma to supersonic velocities, with the magnetic field produced by the thermomagnetic Nernst effect insulating the hot plasma from the cold wall of the centrifuge. Because of the supersonic flow and the high plasma density the configuration is stable.

  20. Thermonuclear dynamo inside ultracentrifuge with supersonic plasma flow stabilization

    Science.gov (United States)

    Winterberg, F.

    2016-01-01

    Einstein's general theory of relativity implies the existence of virtual negative masses in the rotational reference frame of an ultracentrifuge with the negative mass density of the same order of magnitude as the positive mass density of a neutron star. In an ultracentrifuge, the repulsive gravitational field of this negative mass can simulate the attractive positive mass of a mini-neutron star, and for this reason can radially confine a dense thermonuclear plasma placed inside the centrifuge, very much as the positive mass of a star confines its plasma by its own attractive gravitational field. If the centrifuge is placed in an externally magnetic field to act as the seed field of a magnetohydrodynamic generator, the configuration resembles a magnetar driven by the release of energy through nuclear fusion, accelerating the plasma to supersonic velocities, with the magnetic field produced by the thermomagnetic Nernst effect insulating the hot plasma from the cold wall of the centrifuge. Because of the supersonic flow and the high plasma density the configuration is stable.

  1. Thermonuclear dynamo inside ultracentrifuge with supersonic plasma flow stabilization

    International Nuclear Information System (INIS)

    Winterberg, F.

    2016-01-01

    Einstein's general theory of relativity implies the existence of virtual negative masses in the rotational reference frame of an ultracentrifuge with the negative mass density of the same order of magnitude as the positive mass density of a neutron star. In an ultracentrifuge, the repulsive gravitational field of this negative mass can simulate the attractive positive mass of a mini-neutron star, and for this reason can radially confine a dense thermonuclear plasma placed inside the centrifuge, very much as the positive mass of a star confines its plasma by its own attractive gravitational field. If the centrifuge is placed in an externally magnetic field to act as the seed field of a magnetohydrodynamic generator, the configuration resembles a magnetar driven by the release of energy through nuclear fusion, accelerating the plasma to supersonic velocities, with the magnetic field produced by the thermomagnetic Nernst effect insulating the hot plasma from the cold wall of the centrifuge. Because of the supersonic flow and the high plasma density the configuration is stable

  2. [Effect of continuous renal replacement therapy on the plasma concentration of imipenem in severe infection patients with acute renal injury].

    Science.gov (United States)

    Yu, Bin; Liu, Lixia; Xing, Dong; Zhao, Congcong; Hu, Zhenjie

    2015-05-01

    To investigate the extracorporeal clearance rate of imipenem in severe infection patients in the mode of continuous vena-venous hemofiltration (CVVH) during continuous renal replacement therapy (CRRT), in order to approach if the concentration of imipenem in plasma could achieve effective levels of anti-infection, and to explore the effect of time and anticoagulation measure on imipenem clearance during CRRT treatment. A prospective observational study was conducted. All adult severe infection patients complicating acute kidney injury (AKI) in the Department of Critical Care Medicine of the Fourth Hospital of Hebei Medical University from March 2013 to September 2014, who were prescribed imipenem as part of their required medical care, and CRRT for treatment of AKI were enrolled. 0.5 g doses of imipenem was administered intravenously every 6 hours or 8 hours according to random number table, and infused over 0.5 hour. The unfractionated heparin was used for anticoagulation in the patients without contraindications, and no anticoagulation strategy was used in the patients with high risk of bleeding. At 24 hours after first time of administration, postfilter venous blood and ultrafiltrate samples were collected at 0, 0.25, 0.5, 0.75, 1, 2, 5, 6, and 8 hours after imipenem administration. The concentration of imipenem in above samples was determined with liquid chromatography-mass spectrometer/mass spectrometer (LC-MS/MS). A total of 25 patients were enrolled. Thirteen patients received imipenem intravenously every 6 hours, and 12 patients, every 8 hours. The anticoagulation was conducted with heparin in 13 cases, and 12 cases without anticoagulation. The intra-day precision, inter-day precision, matrix effect, and recovery rate in low, medium, and high concentration of plasma and ultrafiltrate, and the stability of samples under different conditions showed a good result, the error of accuracy was controlled in the range of ±15%. With the application of Prismaflex

  3. Prediction of blood pressure and blood flow in stenosed renal arteries using CFD

    Science.gov (United States)

    Jhunjhunwala, Pooja; Padole, P. M.; Thombre, S. B.; Sane, Atul

    2018-04-01

    In the present work an attempt is made to develop a diagnostive tool for renal artery stenosis (RAS) which is inexpensive and in-vitro. To analyse the effects of increase in the degree of severity of stenosis on hypertension and blood flow, haemodynamic parameters are studied by performing numerical simulations. A total of 16 stenosed models with varying degree of stenosis severity from 0-97.11% are assessed numerically. Blood is modelled as a shear-thinning, non-Newtonian fluid using the Carreau model. Computational Fluid Dynamics (CFD) analysis is carried out to compute the values of flow parameters like maximum velocity and maximum pressure attained by blood due to stenosis under pulsatile flow. These values are further used to compute the increase in blood pressure and decrease in available blood flow to kidney. The computed available blood flow and secondary hypertension for varying extent of stenosis are mapped by curve fitting technique using MATLAB and a mathematical model is developed. Based on these mathematical models, a quantification tool is developed for tentative prediction of probable availability of blood flow to the kidney and severity of stenosis if secondary hypertension is known.

  4. Effects of flexible ureteroscopy on renal blood flow: a prospective evaluation.

    Science.gov (United States)

    Sener, Tarik Emre; Tanidir, Yiloren; Bin Hamri, Saeed; Sever, Ibrahim Halil; Ozdemir, Burcu; Al-Humam, Abdulla; Traxer, Olivier

    2018-02-20

    This study aimed to investigate the effects of flexible ureteroscopy (F-URS) on renal blood flow using renal Doppler ultrasound (US). Patients undergoing F-URS were scheduled for Doppler US preoperatively and postoperatively. Peak systolic velocity (PSV), end-diastolic velocity (EDV), resistive index (RI) and pulsatility index (PI) were reported. Technical details, operation time, stone characteristics and complications were recorded. Patients were grouped as 9.5/11.5-Flex-X2, 10/12-Flex-X2, 10/12-Flex-XC, 12/14-Flex-X2 and 12/14-Flex-XC, with 28, six, three, seven and two patients in each group, respectively. Forty-six patients with a mean age of 41.24 years and stone volume of 1685 mm³ were enrolled. The PSV, EDV, PI and RI of renal arteries in all groups in preoperative and postoperative periods were similar. Arcuate artery measurements in all groups were also similar in preoperative and postoperative periods, without any significant difference except in two parameters: RI in the 9.5/11.5-Flex-X2 group and PSV in the 12/14-Flex-X2 group. The resistive index in the arcuate artery of the 9.5/11.5-Flex-X2 group was increased from 0.59 to 0.62 cm/sec postoperatively. The PSV in the arcuate artery of the 12/14-Flex-X2 group was decreased from 30.9 to 27.2 cm/sec. Three patients had urinary tract infections postoperatively and two had sepsis. This study suggests that compatible ureteroscope-ureteral access sheath combinations with a lumen difference of more than 1.5 Fr can provide safe outcomes in terms of renal blood flow. F-URS can safely be performed in terms of renal perfusion and complication rates with appropriate equipment and instruments.

  5. [Value of fractional flow reserve measurement in endovascular therapy for patients with Stanford B type aortic dissection complicated with renal blood flow injury].

    Science.gov (United States)

    Guo, Xi; Li, Peng; Liu, Guangrui; Huang, Xiaoyong; Yong, Qiang; Wang, Guoqin; Huang, Lianjun

    2015-10-01

    To analyze the value of fractional flow reserve (FFR) measurement on endovascular therapy for patients with renal artery stenosis. Clinical data of 12 patients with Stanford B type aortic dissection complicated with renal blood flow injury in Anzhen hospital hospitalized from May 2013 to February 2014 were retrospectively analyzed. Renal artery angiography was performed and fractional flow reserve (FFR) was measured before Thoracic endovascular aortic repair. After operation, renal artery FFR was measured again, and renal artery stenting was performed in patients with FFR ≤ 0.90 or average pressure difference between proximal and distal of renal artery > 20 mmHg (1 mmHg = 0.133 kPa) and not applied for patients with FFR > 0.90.The patients were then subsequently followed up clinically. Kidney function were measured after 1 month, and contrast-enhanced ultrasonography data were obtained at 1 and 3 months later, respectively. The FFR of 1 patient was 0.90, while the FFR of other patients were less than 0.90 before thoracic endovascular aortic repair. After the procedure,the angiography showed that the blood flow of renal artery in 8 patients were fluency, and the FFR index was over 0.90. There were 4 patients with FFR less than 0.90. After renal artery stenting, the FFR of these 4 patients were all above 0.90. Compared with pre-procedure, blood urea nitrogen ((8.84 ± 3.99) mmol/L vs. (5.18 ± 1.69) mmol/L, P = 0.011) and uric acid ((359.3 ± 77.3) µmol/L vs. (276.9 ± 108.3) µmol/L, P = 0.008) decreased significantly after 1 month, and there was no significant difference in serum creatinine (P = 0.760). Contrast-enhanced ultrasonography results showed that blood flow of renal artery were fluency after 1 month and 3 months. In patients with aortic dissection complicating renal blood flow injury, the FFR measurement is meaningful in evaluating the blood flow status of target organs and guide the endovascular revascularization.

  6. Blood flow quantification from 2D phase contrast MRI in renal arteries using an unsupervised data driven approach

    Energy Technology Data Exchange (ETDEWEB)

    Zoellner, Frank Gerrit [Computer Assisted Clinical Medicine, Faculty of Medicine Mannheim, Univ. of Heidelberg, Mannheim (Germany); Section for Radiology, Dept. of Surgical Sciences, Univ. of Bergen (Norway); Monssen, Jan Ankar [Dept. of Radiology, Haukeland Univ. Hospital, Bergen (Norway); Roervik, Jarie [Section for Radiology, Dept. of Surgical Sciences, Univ. of Bergen (Norway); Dept. of Radiology, Haukeland Univ. Hospital, Bergen (Norway); Lundervold, Arvid [Dept. of Radiology, Haukeland Univ. Hospital, Bergen (Norway); Dept. of Biomedicine, Univ. of Bergen (Norway); Schad, Lothar R. [Computer Assisted Clinical Medicine, Faculty of Medicine Mannheim, Univ. of Heidelberg, Mannheim (Germany)

    2009-07-01

    We present a clustering approach to segment the renal artery from 2D PC Cine MR images to measure arterial blood velocity and flow. Such information is important in grading renal artery stenosis and to support the decision on surgical interventions like percutaneous transluminal angioplasty. Results from 20 data sets (volunteers, 7 patients) show that the renal arteries could be extracted automatically and the corresponding velocity profiles were close (r = 0.977) to that obtained by manual delineations of the vessel areas. (orig.)

  7. Blood flow quantification from 2D phase contrast MRI in renal arteries using an unsupervised data driven approach

    International Nuclear Information System (INIS)

    Zoellner, Frank Gerrit; Monssen, Jan Ankar; Roervik, Jarie; Lundervold, Arvid; Schad, Lothar R.

    2009-01-01

    We present a clustering approach to segment the renal artery from 2D PC Cine MR images to measure arterial blood velocity and flow. Such information is important in grading renal artery stenosis and to support the decision on surgical interventions like percutaneous transluminal angioplasty. Results from 20 data sets (volunteers, 7 patients) show that the renal arteries could be extracted automatically and the corresponding velocity profiles were close (r = 0.977) to that obtained by manual delineations of the vessel areas. (orig.)

  8. Dielectric barrier discharge plasma actuator for flow control

    Science.gov (United States)

    Opaits, Dmitry Florievich

    Electrohydrodynamic (EHD) and magnetohydrodynamic phenomena are being widely studied for aerodynamic applications. The major effects of these phenomena are heating of the gas, body force generation, and enthalpy addition or extraction, [1, 2, 3]. In particular, asymmetric dielectric barrier discharge (DBD) plasma actuators are known to be effective EHD device in aerodynamic control, [4, 5]. Experiments have demonstrated their effectiveness in separation control, acoustic noise reduction, and other aeronautic applications. In contrast to conventional DBD actuators driven by sinusoidal voltages, we proposed and used a voltage profile consisting of nanosecond pulses superimposed on dc bias voltage. This produces what is essentially a non-self-sustained discharge: the plasma is generated by repetitive short pulses, and the pushing of the gas occurs primarily due to the bias voltage. The advantage of this non-self-sustained discharge is that the parameters of ionizing pulses and the driving bias voltage can be varied independently, which adds flexibility to control and optimization of the actuators performance. Experimental studies were conducted of a flow induced in a quiescent room air by a single DBD actuator. A new approach for non-intrusive diagnostics of plasma actuator induced flows in quiescent gas was proposed, consisting of three elements coupled together: the Schlieren technique, burst mode of plasma actuator operation, and 2-D numerical fluid modeling. During the experiments, it was found that DBD performance is severely limited by surface charge accumulation on the dielectric. Several ways to mitigate the surface charge were found: using a reversing DC bias potential, three-electrode configuration, slightly conductive dielectrics, and semi conductive coatings. Force balance measurements proved the effectiveness of the suggested configurations and advantages of the new voltage profile (pulses+bias) over the traditional sinusoidal one at relatively low

  9. Atherosclerotic renal artery stenosis is associated with elevated cell cycle arrest markers related to reduced renal blood flow and postcontrast hypoxia.

    Science.gov (United States)

    Saad, Ahmed; Wang, Wei; Herrmann, Sandra M S; Glockner, James F; Mckusick, Michael A; Misra, Sanjay; Bjarnason, Haraldur; Lerman, Lilach O; Textor, Stephen C

    2016-11-01

    Atherosclerotic renal artery stenosis (ARAS) reduces renal blood flow (RBF), ultimately leading to kidney hypoxia and inflammation. Insulin-like growth factor binding protein-7 (IGFBP-7) and tissue inhibitor of metalloproteinases-2 (TIMP-2) are biomarkers of cell cycle arrest, often increased in ischemic conditions and predictive of acute kidney injury (AKI). This study sought to examine the relationships between renal vein levels of IGFBP-7, TIMP-2, reductions in RBF and postcontrast hypoxia as measured by blood oxygen level-dependent (BOLD) magnetic resonance imaging. Renal vein levels of IGFBP-7 and TIMP-2 were obtained in an ARAS cohort (n= 29) scheduled for renal artery stenting and essential hypertensive (EH) healthy controls (n = 32). Cortical and medullary RBFs were measured by multidetector computed tomography (CT) immediately before renal artery stenting and 3 months later. BOLD imaging was performed before and 3 months after stenting in all patients, and a subgroup (N = 12) underwent repeat BOLD imaging 24 h after CT/stenting to examine postcontrast/procedure levels of hypoxia. Preintervention IGFBP-7 and TIMP-2 levels were elevated in ARAS compared with EH (18.5 ± 2.0 versus 15.7 ± 1.5 and 97.4 ± 23.1 versus 62.7 ± 9.2 ng/mL, respectively; Pblood flow (r = -0.59, P= 0.004). These data demonstrate elevated IGFBP-7 and TIMP-2 levels in ARAS as a function of the degree of reduced RBF. Elevated baseline IGFBP-7 levels were associated with protection against postimaging hypoxia, consistent with 'ischemic preconditioning'. Despite contrast injection and stenting, AKI in these high-risk ARAS subjects with elevated IGFBP-7/TIMP-2 was rare and did not affect long-term kidney function. © The Author 2016. Published by Oxford University Press on behalf of ERA-EDTA. All rights reserved.

  10. Critical gradients and plasma flows in the edge plasma of Alcator C-Moda)

    Science.gov (United States)

    Labombard, B.; Hughes, J. W.; Smick, N.; Graf, A.; Marr, K.; McDermott, R.; Reinke, M.; Greenwald, M.; Lipschultz, B.; Terry, J. L.; Whyte, D. G.; Zweben, S. J.; Alcator C-Mod Team

    2008-05-01

    Recent experiments have led to a fundamental shift in our view of edge transport physics; transport near the last-closed flux surface may be more appropriately described in terms of a critical gradient phenomenon rather than a diffusive and/or convective paradigm. Edge pressure gradients, normalized by the square of the poloidal magnetic field strength, appear invariant in plasmas with the same normalized collisionality, despite vastly different currents and magnetic fields—a behavior that connects with first-principles electromagnetic plasma turbulence simulations. Near-sonic scrape-off layer (SOL) flows impose a cocurrent rotation boundary condition on the confined plasma when B ×∇B points toward the active x-point, suggesting a link to the concomitant reduction in input power needed to attain high-confinement modes. Indeed, low-confinement mode plasmas are found to attain higher edge pressure gradients in this configuration, independent of the direction of B, evidence that SOL flows may affect transport and "critical gradient" values in the edge plasma.

  11. Lowering Plasma Glucose Concentration by Inhibiting Renal Sodium-Glucose Co-Transport

    Science.gov (United States)

    Abdul-Ghani, Muhammad A; DeFronzo, Ralph A

    2017-01-01

    Maintaining normoglycaemia not only reduces the risk of diabetic microvascular complications but also corrects the metabolic abnormalities that contribute to the development and progression of hyperglycaemia (i.e. insulin resistance and beta-cell dysfunction). Progressive beta-cell failure, in addition to the multiple side effects associated with many current antihyperglycaemic agents (e.g., hypoglycaemia and weight gain) presents major obstacle to the achievement of the recommended goal of glycaemic control in patients with diabetes mellitus (DM). Thus, novel effective therapies are needed for optimal glucose control in subjects with DM. Recently, specific inhibitors of renal sodium glucose cotransporter 2 (SGLT2) have been developed to produce glucosuria and lower the plasma glucose concentration. Because of their unique mechanism of action (which is independent of the secretion and action of insulin), these agents are effective in lowering the plasma glucose concentration in all stages of DM and can be combined with all other antidiabetic agents. In this review, we summarize the available data concerning the mechanism of action, efficacy and safety of this novel class of antidiabetic agent. PMID:24690096

  12. Association between exercise intensity and renal blood flow evaluated using ultrasound echo.

    Science.gov (United States)

    Kawakami, Shotaro; Yasuno, Tetsuhiko; Matsuda, Takuro; Fujimi, Kanta; Ito, Ai; Yoshimura, Saki; Uehara, Yoshinari; Tanaka, Hiroaki; Saito, Takao; Higaki, Yasuki

    2018-03-10

    High-intensity exercise reduces renal blood flow (RBF) and may transiently exacerbate renal dysfunction. RBF has previously been measured invasively by administration of an indicator material; however, non-invasive measurement is now possible with technological innovations. This study examined variations in RBF at different exercise intensities using ultrasound echo. Eight healthy men with normal renal function (eGFR cys 114 ± 19 mL/min/1.73 m 2 ) participated in this study. Using a bicycle ergometer, participants underwent an incremental exercise test using a ramp protocol (20 W/min) until exhaustion in Study 1 and the lactate acid breaking point (LaBP) was calculated. Participants underwent a multi-stage test at exercise intensities of 60, 80, 100, 120, and 140% LaBP in Study 2. RBF was measured by ultrasound echo at rest and 5 min after exercise in Study 1 and at rest and immediately after each exercise in Study 2. To determine the mechanisms behind RBF decline, a catheter was placed into the antecubital vein to study vasoconstriction dynamics. RBF after maximum exercise decreased by 51% in Study 1. In Study 2, RBF showed no significant decrease until 80% LaBP, and showed a significant decrease (31%) at 100% LaBP compared with at rest (p blood lactate. Reduction in RBF with exercise above the intensity at LaBP was due to decreased cross-sectional area rather than time-averaged flow velocity.

  13. Coupling-induced complexity in nephron models of renal blood flow regulation

    DEFF Research Database (Denmark)

    Laugesen, Jakob Lund; Sosnovtseva, Olga; Mosekilde, Erik

    2010-01-01

    Marsh DJ. Coupling-induced complexity in nephron models of renal blood flow regulation. Am J Physiol Regul Integr Comp Physiol 298: R997-R1006, 2010. First published February 10, 2010; doi: 10.1152/ajpregu.00714.2009.-Tubular pressure and nephron blood flow time series display two interacting...... oscillations in rats with normal blood pressure. Tubulo-glomerular feedback (TGF) senses NaCl concentration in tubular fluid at the macula densa, adjusts vascular resistance of the nephron's afferent arteriole, and generates the slower, larger-amplitude oscillations (0.02-0.04 Hz). The faster smaller...... of glomerular pressure caused by fluctuations of blood pressure. The oscillations become irregular in animals with chronic high blood pressure. TGF feedback gain is increased in hypertensive rats, leading to a stronger interaction between the two mechanisms. With a mathematical model that simulates tubular...

  14. Quick-fire: Plasma flow driven implosion experiments

    International Nuclear Information System (INIS)

    Baker, W.L.; Bigelow, W.S.; Degnan, J.H.

    1985-01-01

    High speed plasma implosions involving megajoules of energy, and sub-microsecond implosion times are expected to require additional stages of power conditioning between realistic primary energy sources and the implosion system. Plasma flow switches and vacuum inductive stores represent attractive alternates to the high speed fuse and atmospheric store techniques which have been previously reported for powering such plasma experiments. In experiments being conducted at the Air Force Weapons Lab, a washer shaped plasma accelerated to 7-10 cm/microsecond in a coaxial plasma gun configuration, represents the moving element in a vacuum store/power conditioning system of 16.5 nH inductance which stores 1-1.5 MJ at 12-14 MA. At the end of the coaxial gun, the moving element transits the 2cm axial length of the cylindrical implosion gap in 200-400 nS, delivering the magnetic energy to the implosion foil, accelerating the imploding plasma to speeds of 30-40 cm/microsecond in 350-450 nS, and delivering a projected 400 KJ of kinetic energy to the implosion. Experiments have been conducted using the SHIVA STAR capacitor bank operating at 6 MJ stored energy in which performance has been monitored by electrical diagnostics, magnetic probes, and axial and radial viewing high speed visible and X-Ray photographs to assess the performance of the coaxial run and coaxial to radial transition. Time and spectrally resolved X-Ray diagnostics are used to assess implosion quality and performance and results are compared to kinematic and MHD models

  15. Estimation of Flow Channel Parameters for Flowing Gas Mixed with Air in Atmospheric-pressure Plasma Jets

    Science.gov (United States)

    Yambe, Kiyoyuki; Saito, Hidetoshi

    2017-12-01

    When the working gas of an atmospheric-pressure non-equilibrium (cold) plasma flows into free space, the diameter of the resulting flow channel changes continuously. The shape of the channel is observed through the light emitted by the working gas of the atmospheric-pressure plasma. When the plasma jet forms a conical shape, the diameter of the cylindrical shape, which approximates the conical shape, defines the diameter of the flow channel. When the working gas flows into the atmosphere from the inside of a quartz tube, the gas mixes with air. The molar ratio of the working gas and air is estimated from the corresponding volume ratio through the relationship between the diameter of the cylindrical plasma channel and the inner diameter of the quartz tube. The Reynolds number is calculated from the kinematic viscosity of the mixed gas and the molar ratio. The gas flow rates for the upper limit of laminar flow and the lower limit of turbulent flow are determined by the corresponding Reynolds numbers estimated from the molar ratio. It is confirmed that the plasma jet length and the internal plasma length associated with strong light emission increase with the increasing gas flow rate until the rate for the upper limit of laminar flow and the lower limit of turbulent flow, respectively. Thus, we are able to explain the increasing trend in the plasma lengths with the diameter of the flow channel and the molar ratio by using the cylindrical approximation.

  16. [Preclinical diagnostics and correction of the disturbed renal blood flow in the children presenting with diabetic nephropathy].

    Science.gov (United States)

    Aver'ianov, A P; Tkacheva, E N; Bolotova, N V; Filina, N Iu; Ivanova, Iu V; Nikolaeva, N V; Tikhonova, L A

    2011-01-01

    The present study included 86 children aged between 7 and 17 years with type 1 diabetes mellitus from 1 to 15 years in duration. In all the patients, renal blood flow was investigated with the use of ultrasonic dopplerography. The results of the study suggest disturbances of intrarenal hemodynamics that manifested themselves as enhanced resistance of renal arteries from periphery to the centre in the patients at the hyperfiltration stage of diabetic nephropathy (DN) in conjunction with the reduced velocity of blood flow in inter-lobular and segmental arteries. In contrast, the patients at the microalbuminuric stage of diabetic nephropathy exhibited increased resistance and reduced velocity of blood flow in the main renal veins. In 35 patients presenting with diabetic nephropathy, hemodynamic correction was achieved by the application of the traveling pulsed magnetic field (TP-MF) to the renal region using an AMO-ATOS-E apparatus (Russia). This treatment resulted in normalization of the characteristics of renal blood flow. It is concluded that TPMF has good prospects for the use as a component of the combined treatment of diabetic nephropathy.

  17. Radiopharmaceuticals for renal studies

    International Nuclear Information System (INIS)

    Verdera, Silvia

    1994-01-01

    Between the diagnostic techniques using radiopharmaceuticals in nuclear medicine it find renal studies.A brief description about renal glomerular filtration(GFR) and reliability renal plasma flux (ERPF),renal blood flux measurement agents (RBF),renal scintillation agents and radiation dose estimates by organ physiology was given in this study.tabs

  18. Instabilities and vortex dynamics in shear flow of magnetized plasmas

    International Nuclear Information System (INIS)

    Tajima, T.; Horton, W.; Morrison, P.J.; Schutkeker, J.; Kamimura, T.; Mima, K.; Abe, Y.

    1990-03-01

    Gradient-driven instabilities and the subsequent nonlinear evolution of generated vortices in sheared E x B flows are investigated for magnetized plasmas with and without gravity (magnetic curvature) and magnetic shear by using theory and implicit particle simulations. In the linear eigenmode analysis, the instabilities considered are the Kelvin-Helmholtz (K-H) instability and the resistive interchange instability. The presence of the shear flow can stabilize these instabilities. The dynamics of the K-H instability and the vortex dynamics can be uniformly described by the initial flow pattern with a vorticity localization parameter ε. The observed growth of the K-H modes is exponential in time for linearly unstable modes, secular for marginal mode, and absent until driven nonlinearly for linearly stable modes. The distance between two vortex centers experiences rapid merging while the angle θ between the axis of vortices and the external shear flow increases. These vortices proceed toward their overall coalescence, while shedding small-scale vortices and waves. The main features of vortex dynamics of the nonlinear coalescence and the tilt or the rotational instabilities of vortices are shown to be given by using a low dimension Hamiltonian representation for interacting vortex cores in the shear flow. 24 refs., 19 figs., 1 tab

  19. Kolmogorov flow in two dimensional strongly coupled dusty plasma

    Energy Technology Data Exchange (ETDEWEB)

    Gupta, Akanksha; Ganesh, R., E-mail: ganesh@ipr.res.in; Joy, Ashwin [Institute for Plasma Research, Bhat Gandhinagar, Gujarat 382 428 (India)

    2014-07-15

    Undriven, incompressible Kolmogorov flow in two dimensional doubly periodic strongly coupled dusty plasma is modelled using generalised hydrodynamics, both in linear and nonlinear regime. A complete stability diagram is obtained for low Reynolds numbers R and for a range of viscoelastic relaxation time τ{sub m} [0 < τ{sub m} < 10]. For the system size considered, using a linear stability analysis, similar to Navier Stokes fluid (τ{sub m} = 0), it is found that for Reynolds number beyond a critical R, say R{sub c}, the Kolmogorov flow becomes unstable. Importantly, it is found that R{sub c} is strongly reduced for increasing values of τ{sub m}. A critical τ{sub m}{sup c} is found above which Kolmogorov flow is unconditionally unstable and becomes independent of Reynolds number. For R < R{sub c}, the neutral stability regime found in Navier Stokes fluid (τ{sub m} = 0) is now found to be a damped regime in viscoelastic fluids, thus changing the fundamental nature of transition of Kolmogorov flow as function of Reynolds number R. A new parallelized nonlinear pseudo spectral code has been developed and is benchmarked against eigen values for Kolmogorov flow obtained from linear analysis. Nonlinear states obtained from the pseudo spectral code exhibit cyclicity and pattern formation in vorticity and viscoelastic oscillations in energy.

  20. Renal papillary necrosis

    Science.gov (United States)

    ... asking your provider. Alternative Names Necrosis - renal papillae; Renal medullary necrosis Images Kidney anatomy Kidney - blood and urine flow References Bushinsky DA, Monk RD. Nephrolithiasis and nephrocalcinosis. ...

  1. [Effects of the renal blood flow at different levels by transcutaneous electrical acupoint stimulation combined general anesthesia induced controlled hypotension].

    Science.gov (United States)

    Fang, Jian-Qiao; Zhang, Le-Le; Shao, Xiao-Mei

    2012-11-01

    To observe the intervention of transcutaneous electrical acupoint stimulation (TEAS) on the renal blood flow at different levels of mean arterial pressure (MAP) in controlled hypotension. Forty-two male beagle dogs were randomly divided into seven groups, i. e., the general anesthesia group, the 50% controlled group, the 40% controlled group, the 30% controlled group, the 50% experimental group, the 40% experimental group, and the 30% experimental group, 6 in each group. Beagles in the general anesthesia group were not treated with controlled hypotension, and the target MAP was achieved in those of the rest groups and maintained for 60 min. In the experimental groups, TEAS was applied to bilateral Hegu (LI4), Zusanli (ST36), Sanyinjiao (SP6), and Quchi (LI11) at 2/100 Hz with the stimulation strength of (4 +/- 1) mA starting from the stability of their physiological conditions to 60 min of maintaining the target MAP level. The changes of the renal blood flow were monitored at different time points using laser Doppler. From starting pressure control to the target MAP level, the renal blood flow was significantly lower in the 30% controlled group than in the general anesthesia group and the basic level of the same group (P blood pressure, the renal blood flow was significantly lower in the 50% controlled group, the 40% controlled group, the 30% controlled group, and the 30% experimental group than in the general anesthesia group (P blood pressure recovery, the renal blood flow restored to the basic level in the 50% controlled group, the 50% experimental group, and the 40% experimental group (P > 0.05), while it was not restored to the basic level in the 40% controlled group, the 30% controlled group, and the 30% experimental group (P renal blood flow, thus protecting the kidney.

  2. Relaxation of plasma potential and poloidal flows in the boundary of tokamak plasmas

    International Nuclear Information System (INIS)

    Hron, M.; Duran, I.; Stoeckel, J.; Hidalgo, C.; Gunn, J.

    2003-01-01

    The relaxation times of plasma parameters after a sudden change of electrode voltage have been measured in the plasma boundary during polarization experiments on the CASTOR tokamak (R = 0.4 m, a = 75 mm, B t = 1 T, I p ∼ 9 kA, q a ∼ 10). The time evolution of the floating potential after the biasing voltage switch-off can be well fitted by an exponential decay with characteristic time in the range of 10 - 20 μs. The poloidal flow shows a transient behaviour with a time scale of about 10 - 30 μs. These time scales are smaller than the expected damping time based on neoclassical parallel viscosity (which is in the range of 100 νs) and atomic physics via charge exchange (in the range of 100 - 1000 νs). But, they are larger than the correlation time of plasma turbulence (about 5 μs). These findings suggest that anomalous damping rate mechanisms for radial electric fields and poloidal flows may play a role in the boundary of tokamak plasmas. (authors)

  3. INTERACTIONS OF FLOWING PLASMA WITH COLLECTING SPHERE/OBJECTS

    Energy Technology Data Exchange (ETDEWEB)

    HUTCHINSON, IAN H.

    2013-10-31

    The proposer’s computational flowing plasma group, supported in part by NSF/DOE since 2006, has been enormously productive. It has published 22 journal articles, of which 3 are in Physical Review Letters; received a total of 330 citations, and made 5 invited and numerous contributed presentations at international conferences. In addition, other groups have published at least 3 papers [20-22] based upon results they have obtained from the SCEPTIC code, developed by the proposer. The codes developed for this subject are Particle In Cell (PIC) codes, representing the entire ion distribution function and its variation in space in the vicinity of an absorbing object.

  4. Evolution of an electron plasma vortex in a strain flow

    Science.gov (United States)

    Danielson, J. R.

    2016-10-01

    Coherent vortex structures are ubiquitous in fluids and plasmas and are examples of self-organized structures in nonlinear dynamical systems. The fate of these structures in strain and shear flows is an important issue in many physical systems, including geophysical fluids and shear suppression of turbulence in plasmas. In two-dimensions, an inviscid, incompressible, ideal fluid can be modeled with the Euler equations, which is perhaps the simplest system that supports vortices. The Drift-Poisson equations for pure electron plasmas in a strong, uniform magnetic field are isomorphic to the Euler equations, and so electron plasmas are an excellent test bed for the study of 2D vortex dynamics. This talk will describe results from a new experiment using pure electron plasmas in a specially designed Penning-Malmberg (PM) trap to study the evolution of an initially axisymmetric 2D vortex subject to externally imposed strains. Complementary vortex-in-cell simulations are conducted to validate the 2D nature of the experimental results and to extend the parameter range of these studies. Data for vortex destruction using both instantaneously applied and time dependent strains with flat (constant vorticity) and extended radial profiles will be presented. The role of vortex self-organization will be discussed. A simple 2D model works well for flat vorticity profiles. However, extended profiles exhibit more complicated behavior, such as filamentation and stripping; and these effects and their consequences will be discussed. Work done in collaboration with N. C. Hurst, D. H. E. Dubin, and C. M. Surko.

  5. A segmented K-space velocity mapping protocol for quantification of renal artery blood flow during breath-holding

    DEFF Research Database (Denmark)

    Thomsen, C; Cortsen, M; Söndergaard, L

    1995-01-01

    for renal artery flow determination. The protocol uses 16 phase-encoding lines per heart beat during 16 heart cycles and gives a temporal velocity resolution of 160 msec. Comparison with a conventional ECG-triggered velocity mapping protocol was made in phantoms as well as in volunteers. In our study, both...... methods showed sufficient robustness toward complex flow in a phantom model. In comparison with the ECG technique, the segmentation technique reduced vessel blurring and pulsatility artifacts caused by respiratory motion, and average flow values obtained in vivo in the left renal artery agreed between......Two important prerequisites for MR velocity mapping of pulsatile motion are synchronization of the sequence execution to the time course of the flow pattern and robustness toward loss of signal in complex flow fields. Synchronization is normally accomplished by using either prospective ECG...

  6. Clinical significance of determination of plasma leptin, NPY and serum Hcy levels in patients with chronic renal diseases

    International Nuclear Information System (INIS)

    Lu Zhifeng

    2010-01-01

    Objective: To study the relationship between progress of disease and blood levels of leptin, NPY, Hcy in patients with chronic renal diseases. Methods: Plasma leptin, NPY (with RIA) and serum Hcy (with CLIA) were determined in (1) 32 patients with chronic pyelonephritis (2) 28 patients with dibetic nephropathy (3) 30 patients with chronic renal failure and (4) 30 controls. Results: Blood levels of leptin, NPY and Hcy were slightly higher in patients with chronic pyelonephritis than those in controls but without significance (P>0.05). In patients with diabetic nephropathy, the plasma leptin and serum Hcy levels were significantly higher than those in controls (P 0.05). In patients with chronic renal failure,the blood levels of NPY (P<0.05) and leptin, Hcy (P<0.01) were all significantly higher than those in controls. Conclusion: Blood levels of these three parameters especially leptin and Hcy, were increased in patients with chronic renal diseases and the increase was most significant in advanced cases. (authors)

  7. Investigation on Plasma Jet Flow Phenomena During DC Air Arc Motion in Bridge-Type Contacts

    Science.gov (United States)

    Zhai, Guofu; Bo, Kai; Chen, Mo; Zhou, Xue; Qiao, Xinlei

    2016-05-01

    Arc plasma jet flow in the air was investigated under a bridge-type contacts in a DC 270 V resistive circuit. We characterized the arc plasma jet flow appearance at different currents by using high-speed photography, and two polished contacts were used to search for the relationship between roughness and plasma jet flow. Then, to make the nature of arc plasma jet flow phenomena clear, a simplified model based on magnetohydrodynamic (MHD) theory was established and calculated. The simulated DC arc plasma was presented with the temperature distribution and the current density distribution. Furthermore, the calculated arc flow velocity field showed that the circular vortex was an embodiment of the arc plasma jet flow progress. The combined action of volume force and contact surface was the main reason of the arc jet flow. supported by National Natural Science Foundation of China (Nos. 51307030, 51277038)

  8. Anatomic and hemodynamic evaluation of renal venous flow in varicocele formation using color Doppler sonography with emphasis on renal vein entrapment syndrome.

    Science.gov (United States)

    Unlu, Murat; Orguc, Sebnem; Serter, Selim; Pekindil, Gokhan; Pabuscu, Yuksel

    2007-01-01

    To investigate the anatomic and hemodynamic properties of testicular venous drainage and its effects on varicocele formation and reflux using color Doppler ultrasound (US) with emphasis on renal vein entrapment syndrome. Upper abdominal and scrotal US examinations of 35 varicocele patients and 35 healthy male subjects were performed in the supine position during rest, during a Valsalva maneuver and in the erect position. The aortomesenteric angle and distance (AMA and AMD, respectively), peak mean velocities (PVs) and diameters of different segments of renal veins, testicular vein diameters and duration of flow inversion were measured. In the varicocele group, the lateral segment of the left renal vein (LRV) had a larger diameter and slower PV, and the medial segment of the LRV had a smaller diameter and faster PV. The diameter of the dominant draining vein correlated with the PV of the medial and lateral segments of the LRV, whereas there was no correlation between the diameter of the dominant draining vein and the diameters of the right renal vein (RRV) and the lateral segment of the LRV or the PV of the RRV. The duration of flow inversion correlated with the diameter and PV of the medial segment of the LRV. No correlation between the diameters and PVs of the RRV and the lateral segment of the LRV was detected. The decreases in the AMA, AMD, diameter of the medial segment of the LRV and PV of the lateral segment of the LRV, and the increases in the PV of the medial segment of the LRV and the diameter of the lateral segment of the LRV in varicocele patients in all positions suggest the entrapment or impingement of the left renal vein between the aorta and the superior mesenteric artery. This has been defined as the "nutcracker phenomenon", which is known to affect varicocele formation.

  9. Miniaturized heat flux sensor for high enthalpy plasma flow characterization

    International Nuclear Information System (INIS)

    Gardarein, Jean-Laurent; Battaglia, Jean-Luc; Lohlec, Stefan; Jullien, Pierre; Van Ootegemd, Bruno; Couzie, Jacques; Lasserre, Jean-Pierre

    2013-01-01

    An improved miniaturized heat flux sensor is presented aiming at measuring extreme heat fluxes of plasma wind tunnel flows. The sensor concept is based on an in-depth thermocouple measurement with a miniaturized design and an advanced calibration approach. Moreover, a better spatial estimation of the heat flux profile along the flow cross section is realized with this improved small sensor design. Based on the linearity assumption, the heat flux is determined using the impulse response of the sensor relating the heat flux to the temperature of the embedded thermocouple. The non-integer system identification (NISI) procedure is applied that allows a calculation of the impulse response from transient calibration measurements with a known heat flux of a laser source. The results show that the new sensor leads to radially highly resolved heat flux measurement for a flow with only a few centimetres in diameter, the so far not understood non-symmetric heat flux profiles do not occur with the new sensor design. It is shown that this former effect is not a physical effect of the flow, but a drawback of the classical sensor design. (authors)

  10. A case of reocclusion of the renal artery diagnosed by the color Doppler method with evaluation of blood flow direction in the collateral circulation of the kidney in addition to the non-detectable blood signal in the renal artery.

    Science.gov (United States)

    Hirano, Megumi; Ohta, Tomoyuki; Nakata, Norio; Kawakami, Reina; Takamura, Kimihiro; Matsuda, Tosiharu; Nishioka, Makiko; Sakurai, Tomoo; Matsuo, Kouichi; Miyamoto, Yukio

    2014-10-01

    A 23-year-old woman was referred to our hospital for an interventional procedure for chronic total occlusion of the right renal artery, probably due to fibromuscular dysplasia (FMD), and for control of renal vascular hypertension. Before percutaneous transluminal renal angioplasty (PTRA), aortography revealed collateral circulation to the right kidney from the lower lumbar artery. After PTRA, however, blood flow in the renal side of the collateral circulation flowed outside from the right renal parenchyma. 4 months later, we could not find a blood flow signal in the right renal artery, and there was a contrary flow signal in the right kidney parenchyma continuously from the extrahilar vessel, possibly a collateral artery. These findings indicated reocclusion of the right artery. We confirmed reocclusion of the renal artery and collateral feeding by contrast dynamic computed tomography (CT), and PTRA was performed again without any complications or reocclusion for 5 months. This is the first case report showing that a back-flowing signal in the right renal parenchyma from the extrahilar artery is useful as an indirect finding suggesting reocclusion.

  11. A Simple Method to Measure Renal Function in Swine by the Plasma Clearance of Iohexol

    Science.gov (United States)

    Luis-Lima, Sergio; García-Contreras, Consolación; Carrara, Fabiola; Negrín-Mena, Natalia; Jiménez-Sosa, Alejandro; Jiménez-Hernández, Hugo; Porrini, Esteban

    2018-01-01

    There is no simple method to measure glomerular filtration rate (GFR) in swine, an established model for studying renal disease. We developed a protocol to measure GFR in conscious swine by using the plasma clearance of iohexol. We used two groups, test and validation, with eight animals each. Ten milliliters of iohexol (6.47 g) was injected into the marginal auricular vein and blood samples (3 mL) were collected from the orbital sinus at different points after injection. GFR was determined using two models: two-compartment (CL2: all samples) and one-compartment (CL1: the last six samples). In the test group, CL1 overestimated CL2 by ~30%: CL2 = 245 ± 93 and CL1 = 308 ± 123 mL/min. This error was corrected by a first-order polynomial quadratic equation to CL1, which was considered the simplified method: SM = −47.909 + (1.176xCL1) − (0.00063968xCL12). The SM showed narrow limits of agreement with CL2, a concordance correlation of 0.97, and a total deviation index of 14.73%. Similar results were obtained for the validation group. This protocol is reliable, reproducible, can be performed in conscious animals, uses a single dose of the marker, and requires a reduced number of samples, and avoids urine collection. Finally, it presents a significant improvement in animal welfare conditions and handling necessities in experimental trials. PMID:29329247

  12. A Simple Method to Measure Renal Function in Swine by the Plasma Clearance of Iohexol

    Directory of Open Access Journals (Sweden)

    Sergio Luis-Lima

    2018-01-01

    Full Text Available There is no simple method to measure glomerular filtration rate (GFR in swine, an established model for studying renal disease. We developed a protocol to measure GFR in conscious swine by using the plasma clearance of iohexol. We used two groups, test and validation, with eight animals each. Ten milliliters of iohexol (6.47 g was injected into the marginal auricular vein and blood samples (3 mL were collected from the orbital sinus at different points after injection. GFR was determined using two models: two-compartment (CL2: all samples and one-compartment (CL1: the last six samples. In the test group, CL1 overestimated CL2 by ~30%: CL2 = 245 ± 93 and CL1 = 308 ± 123 mL/min. This error was corrected by a first-order polynomial quadratic equation to CL1, which was considered the simplified method: SM = −47.909 + (1.176xCL1 − (0.00063968xCL12. The SM showed narrow limits of agreement with CL2, a concordance correlation of 0.97, and a total deviation index of 14.73%. Similar results were obtained for the validation group. This protocol is reliable, reproducible, can be performed in conscious animals, uses a single dose of the marker, and requires a reduced number of samples, and avoids urine collection. Finally, it presents a significant improvement in animal welfare conditions and handling necessities in experimental trials.

  13. Structure of the radial electric field and toroidal/poloidal flow in high temperature toroidal plasma

    International Nuclear Information System (INIS)

    Ida, Katsumi

    2001-01-01

    The structure of the radial electric field and toroidal/poloidal flow is discussed for the high temperature plasma in toroidal systems, tokamak and Heliotron type magnetic configurations. The spontaneous toroidal and poloidal flows are observed in the plasma with improved confinement. The radial electric field is mainly determined by the poloidal flow, because the contribution of toroidal flow to the radial electric field is small. The jump of radial electric field and poloidal flow are commonly observed near the plasma edge in the so-called high confinement mode (H-mode) plasmas in tokamaks and electron root plasma in stellarators including Heliotrons. In general the toroidal flow is driven by the momentum input from neutral beam injected toroidally. There is toroidal flow not driven by neutral beam in the plasma and it will be more significant in the plasma with large electric field. The direction of these spontaneous toroidal flows depends on the symmetry of magnetic field. The spontaneous toroidal flow driven by the ion temperature gradient is in the direction to increase the negative radial electric field in tokamak. The direction of spontaneous toroidal flow in Heliotron plasmas is opposite to that in tokamak plasma because of the helicity of symmetry of the magnetic field configuration. (author)

  14. Plasma-enhanced mixing and flameholding in supersonic flow.

    Science.gov (United States)

    Firsov, Alexander; Savelkin, Konstantin V; Yarantsev, Dmitry A; Leonov, Sergey B

    2015-08-13

    The results of experimental study of plasma-based mixing, ignition and flameholding in a supersonic model combustor are presented in the paper. The model combustor has a length of 600 mm and cross section of 72 mm width and 60 mm height. The fuel is directly injected into supersonic airflow (Mach number M=2, static pressure P(st)=160-250 Torr) through wall orifices. Two series of tests are focused on flameholding and mixing correspondingly. In the first series, the near-surface quasi-DC electrical discharge is generated by flush-mounted electrodes at electrical power deposition of W(pl)=3-24 kW. The scope includes parametric study of ignition and flame front dynamics, and comparison of three schemes of plasma generation: the first and the second layouts examine the location of plasma generators upstream and downstream from the fuel injectors. The third pattern follows a novel approach of combined mixing/ignition technique, where the electrical discharge distributes along the fuel jet. The last pattern demonstrates a significant advantage in terms of flameholding limit. In the second series of tests, a long discharge of submicrosecond duration is generated across the flow and along the fuel jet. A gasdynamic instability of thermal cavity developed after a deposition of high-power density in a thin plasma filament promotes the air-fuel mixing. The technique studied in this work has weighty potential for high-speed combustion applications, including cold start/restart of scramjet engines and support of transition regime in dual-mode scramjet and at off-design operation. © 2015 The Author(s) Published by the Royal Society. All rights reserved.

  15. Interaction of counter-streaming plasma flows in dipole magnetic field

    OpenAIRE

    Shaikhislamov, I F; Posukh, V G; Melekhov, A V; Prokopov, P A; Boyarintsev, E L; Zakharov, Yu P; Ponomarenko, A G

    2017-01-01

    Transient interaction of counter-streaming super-sonic plasma flows in dipole magnetic dipole is studied in laboratory experiment. First quasi-stationary flow is produced by teta-pinch and forms a magnetosphere around the magnetic dipole while laser beams focused at the surface of the dipole cover launch second explosive plasma expanding from inner dipole region outward. Laser plasma is energetic enough to disrupt magnetic field and to sweep through the background plasma for large distances. ...

  16. A Case of Left Renal Vein Ligation in a Patient with Solitary Left Kidney Undergoing Liver Transplantation to Control Splenorenal Shunt and Improve Portal Venous Flow.

    Science.gov (United States)

    Martino, Rodrigo B; Júnior, Eserval Rocha; Manuel, Valdano; Rocha-Santos, Vinicius; D'Albuquerque, Luis Augusto C; Andraus, Wellington

    2017-10-11

    BACKGROUND Adequate portal venous flow is required for successful liver transplantation. Reduced venous flow and blood flow 'steal' by collateral vessels are a concern, and when there is a prominent splenorenal shunt present, ligation of the left renal vein has been recommended to improve portal venous blood flow. CASE REPORT A 51-year-old man who had undergone right nephrectomy in childhood required liver transplantation for liver cirrhosis and hepatocellular carcinoma due to hepatitis C virus (HCV) infection. The patient had no other comorbidity and no history of hepatorenal syndrome. At transplantation surgery, portal venous flow was poor and did not improve with ligation of shunt veins, but ligation of the left renal vein improved portal venous flow. On the first and fifth postoperative days, the patient was treated with basiliximab, a chimeric monoclonal antibody to the IL-2 receptor, and methylprednisolone. The calcineurin inhibitor, tacrolimus, was introduced on the fifth postoperative day. On the sixteenth postoperative day, renal color Doppler ultrasound showed normal left renal parenchyma; hepatic Doppler ultrasound showed good portal vein flow and preserved hepatic parenchyma in the liver transplant. CONCLUSIONS This case report has shown that in a patient with a single left kidney, left renal vein ligation is feasible and safe in a patient with no other risk factors for renal impairment following liver transplantation. Modification of postoperative immunosuppression to avoid calcineurin inhibitors in the very early postoperative phase may be important in promoting good recovery of renal function and to avoid the need for postoperative renal dialysis.

  17. Influence of pre-hydration and pharmacogenetics on plasma methotrexate concentration and renal dysfunction following high-dose methotrexate therapy.

    Science.gov (United States)

    Yanagimachi, Masakatsu; Goto, Hiroaki; Kaneko, Tetsuji; Naruto, Takuya; Sasaki, Koji; Takeuchi, Masanobu; Tanoshima, Reo; Kato, Hiromi; Yokosuka, Tomoko; Kajiwara, Ryosuke; Fujii, Hisaki; Tanaka, Fumiko; Goto, Shoko; Takahashi, Hiroyuki; Mori, Masaaki; Kai, Sumio; Yokota, Shumpei

    2013-12-01

    High-dose methotrexate therapy (HD-MTX) has been well established for the treatment of childhood acute lymphoblastic leukemia (ALL). The aims of this study were to investigate whether clinical and pharmacogenetic factors influence plasma MTX concentration and renal dysfunction in patients treated with HD-MTX. In a total of 127 courses of HD-MTX in 51 patients with childhood ALL, influence of clinical and pharmacogenetic factors on plasma MTX concentration and HD-MTX-related renal dysfunction was evaluated. Clinical factors included age, gender, duration of HD-MTX continuous-infusion and duration of pre-hydration before HD-MTX. Pharmacogenetic factors included 5 gene polymorphisms within the MTX pathway genes, namely, SLC19A1, MTHFR, ABCC2 and ABCG2. Short duration of pre-hydration before HD-MTX is the most important risk factor for prolonged high MTX concentration (p < 0.001, OR 6.40, 95 % CI 2.39-17.16) and renal dysfunction (p = 0.013, OR 3.15, 95 % CI 1.27-7.80). The T allele at MTHFR C677T was the risk factor for prolonged high MTX concentration (p = 0.009, OR 5.54, 95 % CI 1.54-19.85), but not for renal dysfunction. We found the influence of MTHFR C677T polymorphism on prolonged high MTX concentration. We reconfirmed the importance of adequate pre-hydration before HD-MTX to prevent prolonged high MTX concentration and MTX-related renal dysfunction.

  18. Noninvasive measurement of renal blood flow by magnetic resonance imaging in rats.

    Science.gov (United States)

    Romero, Cesar A; Cabral, Glauber; Knight, Robert A; Ding, Guangliang; Peterson, Edward L; Carretero, Oscar A

    2018-01-01

    Renal blood flow (RBF) provides important information regarding renal physiology and nephropathies. Arterial spin labeling-magnetic resonance imaging (ASL-MRI) is a noninvasive method of measuring blood flow without exogenous contrast media. However, low signal-to-noise ratio and respiratory motion artifacts are challenges for RBF measurements in small animals. Our objective was to evaluate the feasibility and reproducibility of RBF measurements by ASL-MRI using respiratory-gating and navigator correction methods to reduce motion artifacts. ASL-MRI images were obtained from the kidneys of Sprague-Dawley (SD) rats on a 7-Tesla Varian MRI system with a spin-echo imaging sequence. After 4 days, the study was repeated to evaluate its reproducibility. RBF was also measured in animals under unilateral nephrectomy and in renal artery stenosis (RST) to evaluate the sensitivity in high and low RBF models, respectively. RBF was also evaluated in Dahl salt-sensitive (SS) rats and spontaneous hypertensive rats (SHR). In SD rats, the cortical RBFs (cRBF) were 305 ± 59 and 271.8 ± 39 ml·min -1 ·100 g tissue -1 in the right and left kidneys, respectively. Retest analysis revealed no differences ( P = 0.2). The test-retest reliability coefficient was 92 ± 5%. The cRBFs before and after the nephrectomy were 296.8 ± 30 and 428.2 ± 45 ml·min -1 ·100 g tissue -1 ( P = 0.02), respectively. The kidneys with RST exhibited a cRBF decrease compared with sham animals (86 ± 17.6 vs. 198 ± 33.7 ml·min -1 ·100 g tissue -1 ; P < 0.01). The cRBFs in SD, Dahl-SS, and SHR rats were not different ( P = 0.35). We conclude that ASL-MRI performed with navigator correction and respiratory gating is a feasible and reliable noninvasive method for measuring RBF in rats.

  19. Supersonic plasma flow between high latitude conjugate ionospheres

    International Nuclear Information System (INIS)

    Roesler, G.

    1975-01-01

    The polar wind problem has been investigated for closed field lines in situations where one of the two conjugate ionospheric regions is fully illuminated by the sun and the other darkness (solstices at high latitudes). A supersonic flow between hemispheres is possible; the magnetospheric part of this flow must be symmetric with respect to the equator. The daytime fluxes are proportional to the neutral hydrogen density. Fluxes of the order of 10 8 cm -2 sec -1 are only possible with density considerably higher than given by CIRA models. For stationary solutions higher flow speeds are needed on the dark side than provided from the illuminated side. It is concluded that shock waves with upward velocities of about 5 km/sec would form above the dark ionosphere. This implies a reduction by a factor of 3 to 5 of the plasma influx into the dark hemisphere, whereby F-layer densities of only up to 2 x 10 4 cm -3 can be maintained. (orig.) [de

  20. Plasma equilibria and stationary flows in axisymmetric systems. Pt. 3

    International Nuclear Information System (INIS)

    Zelazny, R.; Stankiewicz, R.; Galkowski, A.; Potempski, S.; Pietak, R.

    1990-08-01

    The problem of the importance of poloidal flows for the behaviour of plasmas in axisymmetric systems has caused a lot of discussion and controversy during the last 15 years. There is no doubt that the mere existence of poloidal flow transforms the elliptic Grad-Shafranov-Schlueter equation into a system of mixed type partial differential equation and an algebraic multivalued Bernoulli equation. This fact leads to the appearance of Bernoulli branches in the solutions. Then, one can come across three branches of elliptic solutions as well as two branches of hyperbolic solutions with the possible appearance of phenomena connected with ''transsonic'' effects. Problems connected with such a mathematical situation have been extensively discussed in the report with the same title, dated May 1988, which we shall call later Part I of our studies on this subject. The present report, considered as Part III, is devoted to the presentation of results of efforts aimed at constructing programmes which allow us to solve the extended Grad-Shafranov-Schlueter equation (EGSS) (with stationary flows) in a more realistic situation relevant to the JET operating conditions. The main problem is to specify for a wider class of profiles the boundary conditions at the magnetic axis for a system of nonlinear ordinary differential equations ODE, resulting from EGSS equation after application of Fourier transformation techniques and of inverse method approach. The present report elaborates a much more general case and describes the computational framework enabling us to derive those boundary conditions. (author)

  1. Acute renal haemodynamic and renin-angiotensin system responses to graded renal artery stenosis in the dog.

    Science.gov (United States)

    Anderson, W P; Johnston, C I; Korner, P I

    1979-01-01

    1. The acute renal haemodynamic and renin-angiotensin system responses to graded renal artery stenosis were studied in chronically instrumented, unanaesthetized dogs. 2. Stenosis was induced over 30 sec by inflation of a cuff around the renal artery to lower distal pressure to 60, 40 or 20 mmHg, with stenosis maintained for 1 hr. This resulted in an immediate fall in renal vascular resistance, but over the next 5--30 min both resistance and renal artery pressure were restored back towards prestenosis values. Only transient increases in systemic arterial blood pressure and plasma renin and angiotensin levels were seen with the two milder stenoses. Despite restoration of renal artery pressure, renal blood flow remained reduced at all grades of stenosis. 3. Pre-treatment with angiotensin I converting enzyme inhibitor or sarosine1, isoleucone8 angiotensin II greatly attenuated or abolished the restoration of renal artery pressure and renal vascular resistance after stenosis, and plasma renin and angiotensin II levels remained high. Renal dilatation was indefinitely maintained, but the normal restoration of resistance and pressure could be simulated by infusing angiotensin II into the renal artery. 4. The effective resistance to blood flow by the stenosis did not remain constant but varied with changes in the renal vascular resistance. PMID:219182

  2. Non-steroidal anti-inflammatory drugs and renal response to exercise

    DEFF Research Database (Denmark)

    Olsen, Niels Vidiendal; Jensen, N G; Hansen, J M

    1999-01-01

    baseline values or exercise-induced decreases in renal plasma flow or glomerular filtration rate. Indomethacin, but not nabumetone, decreased sodium excretion, urine flow rate and free water clearance. The renal response to exercise, however, remained unchanged. In contrast with nabumatone, indomethacin...

  3. The Influence of Positioning of the Nellix Endovascular Aneurysm Sealing System on Suprarenal and Renal Flow: An In Vitro Study.

    Science.gov (United States)

    Boersen, Johannes T; Groot Jebbink, Erik; Van de Velde, Lennart; Versluis, Michel; Lajoinie, Guillaume; Slump, Cornelius H; de Vries, Jean-Paul P M; Reijnen, Michel M P J

    2017-10-01

    To examine the influence of device positioning and infrarenal neck diameter on flow patterns in the Nellix endovascular aneurysm sealing (EVAS) system. The transition of the aortic flow lumen into two 10-mm-diameter stents after EVAS creates a mismatched area. Flow recirculation may affect local wall shear stress (WSS) profiles and residence time associated with atherosclerosis and thrombosis. To examine these issues, 7 abdominal aortic aneurysm flow phantoms were created, including 3 unstented controls and 3 stented models with infrarenal neck diameters of 24, 28, and 32 mm. Stents were positioned within the instructions for use (IFU). Another 28-mm model was created to evaluate lower positioning of the stents outside the IFU (28-mm LP). Flow was visualized using optical particle imaging velocimetry (PIV) and quantified by time-averaged WSS (TAWSS), oscillatory shear index (OSI), and relative residence time (RRT) in the aorta at the anteroposterior (AP) midplane, lateral midplane, and renal artery AP midplane levels. Flow in the aorta AP midplane was similar in all models. Vortices were observed in the stented models in the lateral midplane near the anterior and posterior walls. In the 32-mm IFU and 28-mm LP models, a steady state of vortices appeared, with varying location during a cycle. In all models, a low TAWSS (OSI of 0.5 and peak RRT of 10 4 Pa -1 . This region was more proximally located in the stented models. The 24- and 28-mm IFU models showed flow with a higher velocity at the renal artery inflow compared to controls. TAWSS in the renal artery was lower near the orifice in all models, with the largest area in the 24-mm IFU model. OSI and RRT in the renal artery were near zero for all models. EVAS enhances vorticity proximal to the seal zone, especially with lower positioning of the device and in larger neck diameters. Endobags just below the renal artery affect the flow profile in a minor area of this artery in 24- and 28-mm necks, while lower stent

  4. Induced renal artery stenosis in rabbits: magnetic resonance imaging, angiography, and radionuclide determination of blood volume and blood flow

    International Nuclear Information System (INIS)

    Mitchell, D.G.; Tobin, M.; LeVeen, R.; Tomaczewski, J.; Alavi, A.; Staum, M.; Kundel, H.

    1988-01-01

    To investigate the ability of MRI to detect alterations due to renal ischemia, a rabbit renal artery stenosis (RAS) model was developed. Seven rabbits had RAS induced by surgically encircling the artery with a polyethylene band which had a lumen of 1 mm, 1 to 2 weeks prior to imaging. The stenosis was confirmed by angiography, and the rabbits were then imaged in a 1.4 T research MRI unit. T1 was calculated using four inversion recovery sequences with different inversion times. Renal blood flow, using 113 Sn-microspheres, and regional water content by drying were then measured. The average T1 of the inner medulla was shorter for the ischemia (1574 msec) than for the contralateral kidney (1849 msec), while no change ws noted in the cortex. Ischemic kidneys had less distinct outer medullary zones on IR images with TI = 600 msec than did contralateral or control kidneys. Blood flow to both the cortex and medulla were markedly reduced in ischemic kidneys compared with contralateral kidneys (119.5 vs. 391 ml/min/100 gm for cortex and 19.8 vs. 50.8 ml/min/100 gm for medulla). Renal water and blood content were less affected. Our rabbit model of renal artery stenosis with MRI, radionuclide, and angiographic correlation has the potential to increase our understanding of MR imaging of the rabbit kidney

  5. Zonal flows and turbulence in fluids and plasmas

    Science.gov (United States)

    Parker, Jeffrey Bok-Cheung

    In geophysical and plasma contexts, zonal flows are well known to arise out of turbulence. We elucidate the transition from statistically homogeneous turbulence without zonal flows to statistically inhomogeneous turbulence with steady zonal flows. Starting from the Hasegawa--Mima equation, we employ both the quasilinear approximation and a statistical average, which retains a great deal of the qualitative behavior of the full system. Within the resulting framework known as CE2, we extend recent understanding of the symmetry-breaking 'zonostrophic instability'. Zonostrophic instability can be understood in a very general way as the instability of some turbulent background spectrum to a zonally symmetric coherent mode. As a special case, the background spectrum can consist of only a single mode. We find that in this case the dispersion relation of zonostrophic instability from the CE2 formalism reduces exactly to that of the 4-mode truncation of generalized modulational instability. We then show that zonal flows constitute pattern formation amid a turbulent bath. Zonostrophic instability is an example of a Type I s instability of pattern-forming systems. The broken symmetry is statistical homogeneity. Near the bifurcation point, the slow dynamics of CE2 are governed by a well-known amplitude equation, the real Ginzburg-Landau equation. The important features of this amplitude equation, and therefore of the CE2 system, are multiple. First, the zonal flow wavelength is not unique. In an idealized, infinite system, there is a continuous band of zonal flow wavelengths that allow a nonlinear equilibrium. Second, of these wavelengths, only those within a smaller subband are stable. Unstable wavelengths must evolve to reach a stable wavelength; this process manifests as merging jets. These behaviors are shown numerically to hold in the CE2 system, and we calculate a stability diagram. The stability diagram is in agreement with direct numerical simulations of the quasilinear

  6. Nonlinear vortex structures and Rayleigh instability condition in shear flow plasmas

    International Nuclear Information System (INIS)

    Haque, Q.; Saleem, H.; Mirza, A.M.

    2009-01-01

    Full text: It is shown that the shear flow produced by externally applied electric field can unstable the drift waves. Due to shear flow, the Rayleigh instability condition is modified, which is obtained for both electron-ion and electron-positron-ion plasmas. These shear flow driven drift waves can be responsible for large amplitude electrostatic fluctuations in tokamak edges. In the nonlinear regime, the stationary structures may appear in electron-positron-ion plasmas similar to electron-ion plasmas. The nonlinear vortex structures like counter rotating dipole vortices and vortex chains can be formed with the aid of special type of shear flows. The positrons can be used as a probe in laboratory plasmas, which make it a multi-component plasma. The presence of positrons in electron-ion plasma system can affect the speed and amplitude of the nonlinear vortex structures. This investigation can have application in both laboratory and astrophysical plasmas. (author)

  7. Low-flow CO₂ removal integrated into a renal-replacement circuit can reduce acidosis and decrease vasopressor requirements.

    Science.gov (United States)

    Forster, Christian; Schriewer, Jens; John, Stefan; Eckardt, Kai-Uwe; Willam, Carsten

    2013-07-24

    Lung-protective ventilation in patients with ARDS and multiorgan failure, including renal failure, is often paralleled with a combined respiratory and metabolic acidosis. We assessed the effectiveness of a hollow-fiber gas exchanger integrated into a conventional renal-replacement circuit on CO₂ removal, acidosis, and hemodynamics. In ten ventilated critically ill patients with ARDS and AKI undergoing renal- and respiratory-replacement therapy, effects of low-flow CO₂ removal on respiratory acidosis compensation were tested by using a hollow-fiber gas exchanger added to the renal-replacement circuit. This was an observational study on safety, CO₂-removal capacity, effects on pH, ventilator settings, and hemodynamics. CO₂ elimination in the low-flow circuit was safe and was well tolerated by all patients. After 4 hours of treatment, a mean reduction of 17.3 mm Hg (-28.1%) pCO₂ was observed, in line with an increase in pH. In hemodynamically instable patients, low-flow CO₂ elimination was paralleled by hemodynamic improvement, with an average reduction of vasopressors of 65% in five of six catecholamine-dependent patients during the first 24 hours. Because no further catheters are needed, besides those for renal replacement, the implementation of a hollow-fiber gas exchanger in a renal circuit could be an attractive therapeutic tool with only a little additional trauma for patients with mild to moderate ARDS undergoing invasive ventilation with concomitant respiratory acidosis, as long as no severe oxygenation defects indicate ECMO therapy.

  8. Optical measurements of lateral energy flow and plasma motion in laser-produced plasmas

    International Nuclear Information System (INIS)

    Benjamin, R.F.; Riffle, J.H.

    1979-01-01

    An optical system consisting of a telephoto lens and multi-image camera is described and the experimental results and their implications are presented. We will also describe the opto-electronic system that will measure the time history of the energy flow with sub-nanosecond resolution. The system will be useful to study both one- and two-dimensional geometries. The third optical diagnostic is a laser probe utilizing detection by the opto-electronic system mentioned above. This diagnostic measures plasma motion as well as energy flow. The laser probe and detection system mounts directly onto the target chamber at LASLs Gemini CO 2 laser, causing severe alignment and stability problems whose solutions will be shown

  9. Computational modeling of plasma-flow switched foil implosions

    International Nuclear Information System (INIS)

    Lindemuth, I.R.

    1985-01-01

    A ''plasma-flow'', or ''commutator'', switch has been proposed as a means of achieving high dI/dt in a radially imploding metallic foil plasma. In this concept, an axially moving foil provides the initial coaxial gun discharge path for the prime power source and provides and ''integral'' inductive storage of magnetic energy. As the axially moving foil reaches the end of the coaxial gun, a radially imploding load foil is switched into the circuit. The authors have begun two-dimensional computer modeling of the two-foil implosion system. They use a magnetohydrodynamic (MHD) model which includes tabulated state and transport properties of the metallic foil material. Moving numerical grids are used to achieve adequate resolution of the moving foils. A variety of radiation models are used to compute the radiation generated when the imploding load foil converges on axis. These computations are attempting to examine the interaction of the switching foil with the load foil. In particular, they examine the relationship between foil placement and implosion quality

  10. Radially sheared azimuthal flows and turbulent transport in a cylindrical helicon plasma device

    International Nuclear Information System (INIS)

    Tynan, G R; Burin, M J; Holland, C; Antar, G; Diamond, P H

    2004-01-01

    A radially sheared azimuthal flow is observed in a cylindrical helicon plasma device. The shear flow is roughly azimuthally symmetric and contains both time-stationary and slowly varying components. The turbulent radial particle flux is found to peak near the density gradient maximum and vanishes at the shear layer location. The shape of the radial plasma potential profile associated with the azimuthal E x B flow is predicted accurately by theory. The existence of the mean shear flow in a plasma with finite flow damping from ion-neutral collisions and no external momentum input implies the existence of radial angular momentum transport from the turbulent Reynolds-stress

  11. Stent revascularization restores cortical blood flow and reverses tissue hypoxia in atherosclerotic renal artery stenosis but fails to reverse inflammatory pathways or glomerular filtration rate.

    Science.gov (United States)

    Saad, Ahmed; Herrmann, Sandra M S; Crane, John; Glockner, James F; McKusick, Michael A; Misra, Sanjay; Eirin, Alfonso; Ebrahimi, Behzad; Lerman, Lilach O; Textor, Stephen C

    2013-08-01

    Atherosclerotic renal artery stenosis (ARAS) is known to reduce renal blood flow, glomerular filtration rate (GFR) and amplify kidney hypoxia, but the relationships between these factors and tubulointerstitial injury in the poststenotic kidney are poorly understood. The purpose of this study was to examine the effect of renal revascularization in ARAS on renal tissue hypoxia and renal injury. Inpatient studies were performed in patients with ARAS (n=17; >60% occlusion) before and 3 months after stent revascularization, or in patients with essential hypertension (n=32), during fixed Na(+) intake and angiotensin converting enzyme/angiotensin receptors blockers Rx. Single kidney cortical, medullary perfusion, and renal blood flow were measured using multidetector computed tomography, and GFR by iothalamate clearance. Tissue deoxyhemoglobin levels (R(2)*) were measured by blood oxygen level-dependent MRI at 3T, as was fractional kidney hypoxia (percentage of axial area with R(2)*>30/s). In addition, we measured renal vein levels of neutrophil gelatinase-associated lipocalin, monocyte chemoattractant protein-1, and tumor necrosis factor-α. Pre-stent single kidney renal blood flow, perfusion, and GFR were reduced in the poststenotic kidney. Renal vein neutrophil gelatinase-associated lipocalin, tumor necrosis factor-α, monocyte chemoattractant protein-1, and fractional hypoxia were higher in untreated ARAS than in essential hypertension. After stent revascularization, fractional hypoxia fell (Pblood flow, whereas GFR and neutrophil gelatinase-associated lipocalin, monocyte chemoattractant protein-1, and tumor necrosis factor-α remained unchanged. These data demonstrate that despite reversal of renal hypoxia and partial restoration of renal blood flow after revascularization, inflammatory cytokines and injury biomarkers remained elevated and GFR failed to recover in ARAS. Restoration of vessel patency alone failed to reverse tubulointerstitial damage and partly

  12. Significance of changes of the plasma levels of nitricoxide, endothelin and atrial natriuretic peptide in patients with lupus nephritis complicated with renal failure and receiving hemodialysis

    International Nuclear Information System (INIS)

    Zhang Jie; Shen Dongbo; Li Yijin

    2009-01-01

    Objective: To investigate the clinical significance of changes of plasma levels of nitricoxide(NO), endothelin (ET) and atrial natriuretic peptide (ANP) before and after hemodialysis in lupus nephritis(LN) patients with renal failure. Methods: Plasma NO (with biochemistry) and ET, ANP(with RIA) levels were measured in 32 lupus patients with renal failure both before and after a course of hemodialysis and 32 controls. Results: The plasma levels of NO, ET and ANP in the 32 LN patients with renal failure were significant higher than those in controls (P<0.05) before hemodialysis, the NO, ET and ANP levels were positively correlated with the BUN and creatinine levels. After a course of hemodialysis, plasma NO and ANP decreased significantly (P<0.05), but no significant changes were observed in plasma ET levels. Conclusion: The plasma level of NO, ET and ANP could help to assess the damage of renal function and hemodialysis could lower the level of NO and ANP in LN patients with renal failure. (authors)

  13. The Effect of Renal Denervation on Plasma Adipokine Profile in Patients with Treatment Resistant Hypertension

    Directory of Open Access Journals (Sweden)

    Nina Eikelis

    2017-05-01

    Full Text Available Background: We previously demonstrated the effectiveness of renal denervation (RDN to lower blood pressure (BP at least partially via the reduction of sympathetic stimulation to the kidney. A number of adipocyte-derived factors are implicated in BP control in obesity.Aim: The aim of this study was to examine whether RDN may have salutary effects on the adipokine profile in patients with resistant hypertension (RH.Methods: Fifty seven patients with RH undergoing RDN program have been included in this study (65% males, age 60.8 ± 1.5 years, BMI 32.6 ± 0.7 kg/m2, mean ± SEM. Throughout the study, the patients were on an average of 4.5 ± 2.7 antihypertensive drugs. Automated seated office BP measurements and plasma concentrations of leptin, insulin, non-esterified fatty acids (NEFA, adiponectin and resistin were assessed at baseline and the 3 months after RDN.Results: There was a significant reduction in mean office systolic (168.75 ± 2.57 vs. 155.23 ± 3.17 mmHg, p < 0.001 and diastolic (90.68 ± 2.31 vs. 83.74 ± 2.36 mmHg, p < 0.001 BP 3 months after RDN. Body weight, plasma leptin and resistin levels and heart rate remained unchanged. Fasting insulin concentration significantly increased 3 months after the procedure (20.05 ± 1.46 vs. 29.70 ± 2.51 uU/ml, p = 0.002. There was a significant drop in circulating NEFA at follow up (1.01 ± 0.07 vs. 0.47 ± 0.04 mEq/l, p < 0.001. Adiponectin concentration was significantly higher after RDN (5,654 ± 800 vs. 6,644 ± 967 ng/ml, p = 0.024.Conclusions: This is the first study to demonstrate that RDN is associated with potentially beneficial effects on aspects of the adipokine profile. Increased adiponectin and reduced NEFA production may contribute to BP reduction via an effect on metabolic pathways.Clinical Trial Registration Number: NCT00483808, NCT00888433.

  14. Development of supersonic plasma flows by use of a magnetic nozzle and an ICRF heating

    Energy Technology Data Exchange (ETDEWEB)

    Inutake, M.; Ando, A.; Hattori, K.; Tobari, H.; Hosokawa, Y.; Sato, R.; Hatanaka, M.; Harata, K. [Tohoku Univ., Dept. of Electrical Engineering, Sendai (Japan)

    2004-07-01

    A high-beta, supersonic plasma flow plays a crucial role in MHD phenomena in space and fusion plasmas. There are a few experimental researches on production and control of a fast flowing plasma in spite of a growing significance in the magnetized-plasma flow dynamics. A magneto-plasma-dynamic arc-jet (MPDA) is one of promising devices to produce a supersonic plasma flow and has been utilized as an electric propulsion device with a higher specific impulse and a relatively larger thrust. We have improved the performance of an MPDA to produce a quasi-steady plasma flow with a transonic and supersonic Mach number in a highly-ionized state. There are two methods in order to control an ion-acoustic Mach number of the plasma flow exhausted from an MPDA: one is to use a magnetic Laval nozzle to convert a thermal energy to a flow energy and the other is a combined system of an ion heating and a divergent magnetic nozzle. The former is an analogous method to a compressible air flow and the latter is the method proposed in an advanced thruster for a manned interplanetary space mission. We have clarified the plasma flow characteristics in various shapes of a magnetic field configuration. It was demonstrated that the Mach number of the plasma flow could increase up to almost 3 in a divergent magnetic nozzle field. This paper reports recent results on the flow field improvements: one is on a magnetic-Laval-nozzle effects observed at the muzzle region of the MPDA, and the other is on ICRF (ion-cyclotron-range of frequency) heating of a supersonic plasma by use of a helical antenna. (authors)

  15. Evaluation of Renal Blood Flow in Chronic Kidney Disease Using Arterial Spin Labeling Perfusion Magnetic Resonance Imaging.

    Science.gov (United States)

    Li, Lu-Ping; Tan, Huan; Thacker, Jon M; Li, Wei; Zhou, Ying; Kohn, Orly; Sprague, Stuart M; Prasad, Pottumarthi V

    2017-01-01

    Chronic kidney disease (CKD) is known to be associated with reduced renal blood flow. However, data to-date in humans is limited. In this study, non-invasive arterial spin labeling (ASL) MRI data was acquired in 33 patients with diabetes and stage-3 CKD, and 30 healthy controls. A significantly lower renal blood flow both in cortex (108.4±36.4 vs . 207.3±41.8; pblood flow were correlated with eGFR, and cortical blood flow was found to be confounded by age and BMI. However, in a subset of subjects that were matched for age and BMI (n=6), the differences between CKD and control subjects remained significant both in cortex (107.4±42.8 vs . 187.51±20.44; p=0.002) and medulla (15.43±8.43 vs . 39.18±11.13; p=0.002). A threshold value to separate healthy and CKD was estimated to be Cor_BF=142.9 and Med_BF=24.1. These results support the use of ASL in the evaluation of renal blood flow in patients with moderate level of CKD. Whether these measurements can identify subjects at risk of progressive CKD requires further longitudinal follow-up.

  16. Comparison of ASL and DCE MRI for the non-invasive measurement of renal blood flow: quantification and reproducibility.

    Science.gov (United States)

    Cutajar, Marica; Thomas, David L; Hales, Patrick W; Banks, T; Clark, Christopher A; Gordon, Isky

    2014-06-01

    To investigate the reproducibility of arterial spin labelling (ASL) and dynamic contrast-enhanced (DCE) magnetic resonance imaging (MRI) and quantitatively compare these techniques for the measurement of renal blood flow (RBF). Sixteen healthy volunteers were examined on two different occasions. ASL was performed using a multi-TI FAIR labelling scheme with a segmented 3D-GRASE imaging module. DCE MRI was performed using a 3D-FLASH pulse sequence. A Bland-Altman analysis was used to assess repeatability of each technique, and determine the degree of correspondence between the two methods. The overall mean cortical renal blood flow (RBF) of the ASL group was 263 ± 41 ml min(-1) [100 ml tissue](-1), and using DCE MRI was 287 ± 70 ml min(-1) [100 ml tissue](-1). The group coefficient of variation (CVg) was 18 % for ASL and 28 % for DCE-MRI. Repeatability studies showed that ASL was more reproducible than DCE with CVgs of 16 % and 25 % for ASL and DCE respectively. Bland-Altman analysis comparing the two techniques showed a good agreement. The repeated measures analysis shows that the ASL technique has better reproducibility than DCE-MRI. Difference analysis shows no significant difference between the RBF values of the two techniques. Reliable non-invasive monitoring of renal blood flow is currently clinically unavailable. Renal arterial spin labelling MRI is robust and repeatable. Renal dynamic contrast-enhanced MRI is robust and repeatable. ASL blood flow values are similar to those obtained using DCE-MRI.

  17. Parametric renal blood flow imaging using [{sup 15}O]H{sub 2}O and PET

    Energy Technology Data Exchange (ETDEWEB)

    Kudomi, Nobuyuki; Liukko, Kaisa E.; Oikonen, Vesa J.; Tolvanen, Tuula [University of Turku, Turku PET Centre, P.O. Box 52, Turku (Finland); Koivuviita, Niina; Tertti, Risto; Metsaerinne, Kaj [University of Turku, Department of Medicine, Turku (Finland); Iida, Hidehiro [National Cardiovascular Center-Research Institute, Department of Investigative Radiology, Advanced Medical-Engineering Center, Suita, Osaka (Japan); Iozzo, Patricia [University of Turku, Turku PET Centre, P.O. Box 52, Turku (Finland); National Research Council, Institute of Clinical Physiology, Pisa (Italy); Nuutila, Pirjo [University of Turku, Turku PET Centre, P.O. Box 52, Turku (Finland); University of Turku, Department of Medicine, Turku (Finland)

    2009-04-15

    The quantitative assessment of renal blood flow (RBF) may help to understand the physiological basis of kidney function and allow an evaluation of pathophysiological events leading to vascular damage, such as renal arterial stenosis and chronic allograft nephropathy. The RBF may be quantified using PET with H{sub 2} {sup 15}O, although RBF studies that have been performed without theoretical evaluation have assumed the partition coefficient of water (p, ml/g) to be uniform over the whole region of renal tissue, and/or radioactivity from the vascular space (V{sub A}. ml/ml) to be negligible. The aim of this study was to develop a method for calculating parametric images of RBF (K{sub 1}, k{sub 2}) as well as V{sub A} without fixing the partition coefficient by the basis function method (BFM). The feasibility was tested in healthy subjects. A simulation study was performed to evaluate error sensitivities for possible error sources. The experimental study showed that the quantitative accuracy of the present method was consistent with nonlinear least-squares fitting, i.e. K{sub 1,BFM}=0.93K{sub 1,NLF}-0.11 ml/min/g (r=0.80, p<0.001), k{sub 2,BFM}=0.96k{sub 2,NLF}-0.13 ml/min/g (r=0.77, p<0.001), and V{sub A,BFM}=0.92V{sub A,NLF}-0.00 ml/ml (r=0.97, p<0.001). Values of the Akaike information criterion from this fitting were the smallest for all subjects except two. The quality of parametric images obtained was acceptable. The simulation study suggested that delay and dispersion time constants should be estimated within an accuracy of 2 s. V{sub A} and p cannot be neglected or fixed, and reliable measurement of even relative RBF values requires that V{sub A} is fitted. This study showed the feasibility of measurement of RBF using PET with H{sub 2} {sup 15}O. (orig.)

  18. Discharge characteristics and hydrodynamics behaviors of atmospheric plasma jets produced in various gas flow patterns

    Science.gov (United States)

    Setsuhara, Yuichi; Uchida, Giichiro; Nakajima, Atsushi; Takenaka, Kosuke; Koga, Kazunori; Shiratani, Masaharu

    2015-09-01

    Atmospheric nonequilibrium plasma jets have been widely employed in biomedical applications. For biomedical applications, it is an important issue to understand the complicated mechanism of interaction of the plasma jet with liquid. In this study, we present analysis of the discharge characteristics of a plasma jet impinging onto the liquid surface under various gas flow patterns such as laminar and turbulence flows. For this purpose, we analyzed gas flow patters by using a Schlieren gas-flow imaging system in detail The plasma jet impinging into the liquid surface expands along the liquid surface. The diameter of the expanded plasma increases with gas flow rate, which is well explained by an increase in the diameter of the laminar gas-flow channel. When the gas flow rate is further increased, the gas flow mode transits from laminar to turbulence in the gas flow channel, which leads to the shortening of the plasm-jet length. Our experiment demonstrated that the gas flow patterns strongly affect the discharge characteristics in the plasma-jet system. This study was partly supported by a Grant-in-Aid for Scientific Research on Innovative Areas ``Plasma Medical Innovation'' (24108003) from the Ministry of Education, Culture, Sports, Science and Technology, Japan (MEXT).

  19. Plasma proteomics classifiers improve risk prediction for renal disease in patients with hypertension or type 2 diabetes

    DEFF Research Database (Denmark)

    Pena, Michelle J; Jankowski, Joachim; Heinze, Georg

    2015-01-01

    OBJECTIVE: Micro and macroalbuminuria are strong risk factors for progression of nephropathy in patients with hypertension or type 2 diabetes. Early detection of progression to micro and macroalbuminuria may facilitate prevention and treatment of renal diseases. We aimed to develop plasma...... proteomics classifiers to predict the development of micro or macroalbuminuria in hypertension or type 2 diabetes. METHODS: Patients with hypertension (n = 125) and type 2 diabetes (n = 82) were selected for this case-control study from the Prevention of REnal and Vascular ENd-stage Disease cohort....... RESULTS: In hypertensive patients, the classifier improved risk prediction for transition in albuminuria stage on top of the reference model (C-index from 0.69 to 0.78; P diabetes, the classifier improved risk prediction for transition from micro to macroalbuminuria (C-index from 0...

  20. Energy principle for excitations in plasmas with counterstreaming electron flows

    Science.gov (United States)

    Kumar, Atul; Shukla, Chandrasekhar; Das, Amita; Kaw, Predhiman

    2018-05-01

    A relativistic electron beam propagating through plasma induces a return electron current in the system. Such a system of interpenetrating forward and return electron current is susceptible to a host of instabilities. The physics of such instabilities underlies the conversion of the flow kinetic energy to the electromagnetic field energy. Keeping this in view, an energy principle analysis has been enunciated in this paper. Such analyses have been widely utilized earlier in the context of conducting fluids described by MHD model [I. B. Bernstein et al., Proceedings of the Royal Society of London A: Mathematical, Physical and Engineering Sciences 244(1236), 17-40 (1958)]. Lately, such an approach has been employed for the electrostatic two stream instability for the electron beam plasma system [C. N. Lashmore-Davies, Physics of Plasmas 14(9), 092101 (2007)]. In contrast, it has been shown here that even purely growing mode like Weibel/current filamentation instability for the electron beam plasma system is amenable to such a treatment. The treatment provides an understanding of the energetics associated with the growing mode. The growth rate expression has also been obtained from it. Furthermore, it has been conclusively demonstrated in this paper that for identical values of S4=∑αn0 αv0α 2/n0γ0 α, the growth rate is higher when the counterstreaming beams are symmetric (i.e. S3 = ∑αn0αv 0α/n0γ0α = 0) compared to the case when the two beams are asymmetric (i.e. when S3 is finite). Here, v 0α, n0α and γ0α are the equilibrium velocity, electron density and the relativistic factor for the electron species `α' respectively and n0 = ∑αn0α is the total electron density. Particle - In - Cell simulations have been employed to show that the saturated amplitude of the field energy is also higher in the symmetric case.

  1. βENaC is a molecular component of a VSMC mechanotransducer that contributes to renal blood flow regulation, protection from renal injury, and hypertension.

    Science.gov (United States)

    Drummond, Heather A

    2012-01-01

    Pressure-induced constriction (also known as the "myogenic response") is an important mechano-dependent response in certain blood vessels. The response is mediated by vascular smooth muscle cells (VSMCs) and characterized by a pressure-induced vasoconstriction in small arteries and arterioles in the cerebral, mesenteric, cardiac, and renal beds. The myogenic response has two important roles; it is a mechanism of blood flow autoregulation and provides protection against systemic blood pressure-induced damage to delicate microvessels. However, the molecular mechanism(s) underlying initiation of myogenic response is unclear. Degenerin proteins have a strong evolutionary link to mechanotransduction in the nematode. Our laboratory has addressed the hypothesis that these proteins may also act as mechanosensors in certain mammalian tissues such as VSMCs and arterial baroreceptor neurons. This article discusses the importance of a specific degenerin protein, β Epithelial Na(+) Channel (βENaC) in pressure-induced vasoconstriction in renal vessels and arterial baroreflex function as determined in a mouse model of reduced βENaC (βENaC m/m). We propose that loss of baroreflex sensitivity (due to loss of baroreceptor βENaC) increases blood pressure variability, increasing the likelihood and magnitude of upward swings in systemic pressure. Furthermore, loss of the myogenic constrictor response (due to loss of VSMC βENaC) will permit those pressure swings to be transmitted to the microvasculature in βENaC m/m mice, thus increasing the susceptibility to renal injury and hypertension.

  2. Radionuclide determination of individual kidney function in the treatment of chronic renal obstruction

    International Nuclear Information System (INIS)

    Belis, J.A.; Belis, T.E.; Lai, J.C.; Goodwin, C.A.; Gabriele, O.F.

    1982-01-01

    Differential radionuclide renal scans can be useful in the management of patients with chronic partial obstruction of 1 kidney. The /sup 99m/Tc diethylenetriaminepentaacetic acid perfusion scan can be used to assess glomerular blood flow. The 131 I orthoiodohippurate renal scan provides qualitative functional information from scintigrams and quantitative evaluation of effective renal plasma flow to each kidney, as well as a total excretory index. Sequential /sup 99m/Tc diethylenetriaminepentaacetic acid and 131 I orthoiodohippurate renal scans were used to assess individual renal function before and after surgical correction of unilateral chronic renal obstruction in 31 patients. The preservation of cortical perfusion on /supb 99m/Tc diethylenetriaminepentaacetic acid scans indicated that potential existed for partial recovery of renal function. Effective renal plasma flow and excretory index determined in conjunction with the 131 I orthoiodohippurate scans provided a quantitative assessment of preoperative renal function, an evaluation of the effect of surgery and a sensitive method for long-term evaluation of differential renal function. Correction of ureteropelvic junction obstruction usually resulted in improvement in unilateral renal function. Neither nephrolithotomy nor extended pyelolithotomy diminished renal function in the kidney subjected to an operation and often improved it. Patients with long-standing distal ureteral obstruction had the least improvement in renal function postoperatively

  3. Tripolar vortices of dust-drift waves in dusty plasma with shear flow

    International Nuclear Information System (INIS)

    Chen Yinhua; Wang Ge

    2002-01-01

    Nonlinear equations governing dust-drift waves in magnetized dusty plasma with transverse shear flow are derived. For the specific profiles of flow and the plasma equilibrium density, a new type of solution in the form of tripolar vortices is found. The results show that the peak magnitude of tripolar vortices increases with increasing shear intensity and dust content

  4. Multiprobe characterization of plasma flows for space propulsion

    NARCIS (Netherlands)

    Damba, Julius; Argente, P.; Maldonado, P. E.; Cervone, A.; Domenech-Garret, J.L.; Conde, Luis

    2018-01-01

    Plasma engines for space propulsion generate plasma jets (also denominated plasma plumes) having supersonic ion groups with typical speeds in the order of tens of kilometers per second, which lies between electron and ion thermal speeds. Studies of the stationary plasma expansion process using a

  5. Flow structure formation in an ion-unmagnetized plasma: The HYPER-II experiments

    Science.gov (United States)

    Terasaka, K.; Tanaka, M. Y.; Yoshimura, S.; Aramaki, M.; Sakamoto, Y.; Kawazu, F.; Furuta, K.; Takatsuka, N.; Masuda, M.; Nakano, R.

    2015-01-01

    The HYPER-II device has been constructed in Kyushu University to investigate the flow structure formation in an ion-unmagnetized plasma, which is an intermediate state of plasma and consists of unmagnetized ions and magnetized electrons. High density plasmas are produced by electron cyclotron resonance heating, and the flow field structure in an inhomogeneous magnetic field is investigated with a directional Langmuir probe method and a laser-induced fluorescence method. The experimental setup has been completed and the diagnostic systems have been installed to start the experiments. A set of coaxial electrodes will be introduced to control the azimuthal plasma rotation, and the effect of plasma rotation to generation of rectilinear flow structure will be studied. The HYPER-II experiments will clarify the overall flow structure in the inhomogeneous magnetic field and contribute to understanding characteristic feature of the intermediate state of plasma.

  6. Controlling hydrophilicity of polymer film by altering gas flow rate in atmospheric-pressure homogeneous plasma

    International Nuclear Information System (INIS)

    Kang, Woo Seok; Hur, Min; Lee, Jae-Ok; Song, Young-Hoon

    2014-01-01

    Graphical abstract: - Highlights: • Controlling hydrophilicity of polymer film by varying gas flow rate is proposed in atmospheric-pressure homogeneous plasma treatment. • Without employing additional reactive gas, requiring more plasma power and longer treatment time, hydrophilicity of polyimide films was improved after the low-gas-flow plasma treatment. • The gas flow rate affects the hydrophilic properties of polymer surface by changing the discharge atmosphere in the particular geometry of the reactor developed. • Low-gas-flow induced wettability control suggests effective and economical plasma treatment. - Abstract: This paper reports on controlling the hydrophilicity of polyimide films using atmospheric-pressure homogeneous plasmas by changing only the gas flow rate. The gas flow changed the discharge atmosphere by mixing the feed gas with ambient air because of the particular geometry of the reactor developed for the study, and a low gas flow rate was found to be favorable because it generated abundant nitrogen or oxygen species that served as sources of hydrophilic functional groups over the polymer surface. After low-gas-flow plasma treatment, the polymer surface exhibited hydrophilic characteristics with increased surface roughness and enhanced chemical properties owing to the surface addition of functional groups. Without adding any reactive gases or requiring high plasma power and longer treatment time, the developed reactor with low-gas-flow operation offered effective and economical wettability control of polyimide films

  7. Plasma flow driven by fusion-generated alpha particles

    International Nuclear Information System (INIS)

    Ikuta, Kazunari.

    1978-05-01

    The confinement of fusion-generated alpha particles will affect the transports of the background plasma particles by the momentum transfer from the energetic alphas. The ions tend to migrate towards the center of plasma (i.e. fuel injection) and electrons towards the plasma periphery. This means the existence of a mechanism which enable to pump out the ashes in the fuel plasma because of the momentum conservation of whole plasma particles. (author)

  8. Spectroscopic studies of a high Mach-number rotating plasma flow

    International Nuclear Information System (INIS)

    Ando, Akira; Ashino, Masashi; Sagi, Yukiko; Inutake, Masaaki; Hattori, Kunihiko; Yoshinuma, Mikirou; Imasaki, Atsushi; Tobari, Hiroyuki; Yagai, Tsuyoshi

    2001-01-01

    Characteristics of an axially-magnetized rotating plasma are investigated by spectroscopy in the HITOP device of Tohoku University. A He plasma flows our axially and rotates azimuthally near the muzzle region of the MPD arcjet. Flow and rotational velocities and temperature of He ions and atoms are measured by Doppler shift and broadening of the HeII (γ=468.58 nm) and HeI (γ=587.56 nm) lines. Rotational velocity increases with the increase of axially-applied magnetic field strength and discharge current. As discharge current increases and mass flow rate decreases, the plasma flow velocity increases and T i increases. Ion acoustic Mach number of the plasma flow also increases, but tends to saturate at near 1. Radial profile of space potential is calculated from the obtained rotational velocity. The potential profile in the core region is parabolic corresponding to the observed rigid-body rotation of the core plasma. (author)

  9. Spectroscopic studies of a high Mach-number rotating plasma flow

    Energy Technology Data Exchange (ETDEWEB)

    Ando, Akira; Ashino, Masashi; Sagi, Yukiko; Inutake, Masaaki; Hattori, Kunihiko; Yoshinuma, Mikirou; Imasaki, Atsushi; Tobari, Hiroyuki; Yagai, Tsuyoshi [Tohoku Univ., Dept. of Electrical Engineering, Sendai, Miyagi (Japan)

    2001-07-01

    Characteristics of an axially-magnetized rotating plasma are investigated by spectroscopy in the HITOP device of Tohoku University. A He plasma flows our axially and rotates azimuthally near the muzzle region of the MPD arcjet. Flow and rotational velocities and temperature of He ions and atoms are measured by Doppler shift and broadening of the HeII ({gamma}=468.58 nm) and HeI ({gamma}=587.56 nm) lines. Rotational velocity increases with the increase of axially-applied magnetic field strength and discharge current. As discharge current increases and mass flow rate decreases, the plasma flow velocity increases and T{sub i} increases. Ion acoustic Mach number of the plasma flow also increases, but tends to saturate at near 1. Radial profile of space potential is calculated from the obtained rotational velocity. The potential profile in the core region is parabolic corresponding to the observed rigid-body rotation of the core plasma. (author)

  10. Effects of lornoxicam and intravenous ibuprofen on erythrocyte deformability and hepatic and renal blood flow in rats.

    Science.gov (United States)

    Arpacı, Hande; Çomu, Faruk Metin; Küçük, Ayşegül; Kösem, Bahadır; Kartal, Seyfi; Şıvgın, Volkan; Turgut, Hüseyin Cihad; Aydın, Muhammed Enes; Koç, Derya Sebile; Arslan, Mustafa

    2016-01-01

    Change in blood supply is held responsible for anesthesia-related abnormal tissue and organ perfusion. Decreased erythrocyte deformability and increased aggregation may be detected after surgery performed under general anesthesia. It was shown that nonsteroidal anti-inflammatory drugs decrease erythrocyte deformability. Lornoxicam and/or intravenous (iv) ibuprofen are commonly preferred analgesic agents for postoperative pain management. In this study, we aimed to investigate the effects of lornoxicam (2 mg/kg, iv) and ibuprofen (30 mg/kg, iv) on erythrocyte deformability, as well as hepatic and renal blood flows, in male rats. Eighteen male Wistar albino rats were randomly divided into three groups as follows: iv lornoxicam-treated group (Group L), iv ibuprofen-treated group (Group İ), and control group (Group C). Drug administration was carried out by the iv route in all groups except Group C. Hepatic and renal blood flows were studied by laser Doppler, and euthanasia was performed via intra-abdominal blood uptake. Erythrocyte deformability was measured using a constant-flow filtrometry system. Lornoxicam and ibuprofen increased the relative resistance, which is an indicator of erythrocyte deformability, of rats (P=0.016). Comparison of the results from Group L and Group I revealed no statistically significant differences (P=0.694), although the erythrocyte deformability levels in Group L and Group I were statistically higher than the results observed in Group C (P=0.018 and P=0.008, respectively). Hepatic and renal blood flows were significantly lower than the same in Group C. We believe that lornoxicam and ibuprofen may lead to functional disorders related to renal and liver tissue perfusion secondary to both decreased blood flow and erythrocyte deformability. Further studies regarding these issues are thought to be essential.

  11. Experimental selective elevation of renal medullary blood flow in hypertensive rats: evidence against short-term hypotensive effect.

    Science.gov (United States)

    Bądzyńska, B; Sadowski, J

    2012-08-01

    Renal medullary blood flow (MBF) can be selectively increased by intrarenal or systemic infusion of bradykinin (Bk) in anaesthetized normotensive rats. We reproduced this effect in a number of rat models of arterial hypertension and examined whether increased perfusion of the renal medulla can cause a short-term decrease in blood pressure (BP) that is not mediated by increased renal excretion and depletion of body fluids. In uninephrectomized Sprague-Dawley rats, BP was elevated to approx. 145 mmHg by acute i.v. infusion of noradrenaline (NA) or angiotensin II (Ang II) (groups 1, 2), 2-week exposure to high-salt diet (3), high-salt diet + chronic low-dose infusion of Ang II using osmotic minipumps (4) or chronic high-dose Ang II infusion on normal diet (5). Uninephrectomized spontaneous hypertensive rats (SHR) were also examined (6,7). To selectively increase medullary perfusion, in anaesthetized rats, bradykinin was infused during 30-75 min into the renal medullary interstitium or intravenously. Bradykinin increased outer- and inner-medullary blood flow (laser-Doppler fluxes) by 10-20% in groups (1, 2), by 30-50% in groups (3, 4, 5) and approx. 20% in SHR (6, 7). The concurrent increase in total renal blood flow (Transonic probe) was < 3%. A minor (<3%) decrease in BP was seen only in rats acutely rendered hypertensive by NA or Ang II infusions; however, the decreases in BP and increases in medullary perfusion were not correlated. Thus, there was no evidence that in hypertensive rats, substantial selective increases in medullary perfusion can cause a short-term decrease in BP. © 2012 The Authors Acta Physiologica © 2012 Scandinavian Physiological Society.

  12. Role of Mas receptor in renal blood flow response to angiotensin-(1-7) in ovariectomized estradiol treated rats.

    Science.gov (United States)

    Saberi, Shadan; Dehghani, Aghdas; Nematbakhsh, Mehdi

    2016-01-01

    The angiotensin 1-7 (Ang 1-7), is abundantly produced in kidneys and antagonizes the function of angiotensin II through Mas receptor (MasR) or other unknown mechanisms. In the current study, the role of MasR and steroid hormone estrogen on renal blood flow response to Ang 1-7 administration was investigated in ovariectomized (OV) female rats. OV female Wistar-rats received estradiol (500 μg/kg/week) or vehicle for two weeks. In the day of the experiment, the animals were anesthetized, cannulated, and the responses including mean arterial pressure, renal blood flow (RBF), and renal vascular resistance at the constant level of renal perfusion pressure to graded infusion of Ang 1-7 at 0, 100 and 300 ng/kg/min were determined in OV and OV estradiol-treated (OVE) rats, treated with vehicle or MasR antagonist; A779. RBF response to Ang 1-7 infusion increased dose-dependently in vehicle (Pdose <0.001) and A779-treated (Pdose <0.01) animals. However, when MasR was blocked, the RBF response to Ang 1-7 significantly increased in OV animals compared with OVE rats (P<0.05). When estradiol was limited by ovariectomy, A779 increased RBF response to Ang 1-7 administration, while this response was attenuated in OVE animals.

  13. Computer-aided detection of renal calculi from noncontrast CT images using TV-flow and MSER features

    Science.gov (United States)

    Liu, Jianfei; Wang, Shijun; Turkbey, Evrim B.; Linguraru, Marius George; Yao, Jianhua; Summers, Ronald M.

    2015-01-01

    Purpose: Renal calculi are common extracolonic incidental findings on computed tomographic colonography (CTC). This work aims to develop a fully automated computer-aided diagnosis system to accurately detect renal calculi on CTC images. Methods: The authors developed a total variation (TV) flow method to reduce image noise within the kidneys while maintaining the characteristic appearance of renal calculi. Maximally stable extremal region (MSER) features were then calculated to robustly identify calculi candidates. Finally, the authors computed texture and shape features that were imported to support vector machines for calculus classification. The method was validated on a dataset of 192 patients and compared to a baseline approach that detects calculi by thresholding. The authors also compared their method with the detection approaches using anisotropic diffusion and nonsmoothing. Results: At a false positive rate of 8 per patient, the sensitivities of the new method and the baseline thresholding approach were 69% and 35% (p < 1e − 3) on all calculi from 1 to 433 mm3 in the testing dataset. The sensitivities of the detection methods using anisotropic diffusion and nonsmoothing were 36% and 0%, respectively. The sensitivity of the new method increased to 90% if only larger and more clinically relevant calculi were considered. Conclusions: Experimental results demonstrated that TV-flow and MSER features are efficient means to robustly and accurately detect renal calculi on low-dose, high noise CTC images. Thus, the proposed method can potentially improve diagnosis. PMID:25563255

  14. Four hour creatinine clearance is better than plasma creatinine for monitoring renal function in critically ill patients

    Science.gov (United States)

    2012-01-01

    Introduction Acute kidney injury (AKI) diagnosis is based on an increase in plasma creatinine, which is a slowly changing surrogate of decreased glomerular filtration rate. We investigated whether serial creatinine clearance, a direct measure of the glomerular filtration rate, provided more timely and accurate information on renal function than serial plasma creatinine in critically ill patients. Methods Serial plasma creatinine and 4-hour creatinine clearance were measured 12-hourly for 24 hours and then daily in 484 patients. AKI was defined either as > 50% increase in plasma creatinine from baseline, or > 33.3% decrease in creatinine clearance. The diagnostic and predictive performance of the two AKI definitions were compared. Results Creatinine clearance decrease diagnosed AKI in 24% of those not diagnosed by plasma creatinine increase on entry. These patients entered the ICU sooner after insult than those diagnosed with AKI by plasma creatinine elevation (P = 0.0041). Mortality and dialysis requirement increased with the change in creatinine clearance-acute kidney injury severity class (P = 0.0021). Amongst patients with plasma creatinine creatinine clearance improved the prediction of AKI considerably (Net Reclassification Improvement 83%, Integrated Discrimination Improvement 0.29). On-entry, creatinine clearance associated with AKI severity and duration (P 33.3% decrease in creatinine clearance over the first 12 hours was associated with a 2.0-fold increased relative risk of dialysis or death. Conclusions Repeated 4-hour creatinine clearance measurements in critically ill patients allow earlier detection of AKI, as well as progression and recovery compared to plasma creatinine. Trial Registration Australian New Zealand Clinical Trials Registry ACTRN012606000032550. PMID:22713519

  15. Plasma procalcitonin is an independent predictor of graft failure late after renal transplantation

    NARCIS (Netherlands)

    van Ree, Rutger M.; de Vries, Aiko P. J.; Oterdoom, Leendert H.; Seelen, Marc A.; Gansevoort, Ron T.; Schouten, Jan P.; Struck, Joachim; Navis, Gerjan; Gans, Reinold O. B.; Homan van der Heide, Jaap J.; van Son, Willem J.; Bakker, Stephan J. L.

    2009-01-01

    Chronic low-grade inflammation is involved in chronic transplant dysfunction after renal transplantation. Procalcitonin (PCT), known to reflect microbial inflammation, may also reflect ongoing noninfectious chronic low-grade inflammation in organ parenchyma, including transplanted kidneys. We aimed

  16. Plasma Procalcitonin Is an Independent Predictor of Graft Failure Late After Renal Transplantation

    NARCIS (Netherlands)

    van Ree, Rutger M.; de Vries, Aiko P. J.; Oterdoom, Leendert H.; Seelen, Marc A.; Gansevoort, Ron T.; Schouten, Jan P.; Struck, Joachim; Navis, Gerjan; Gans, Reinold O. B.; van der Heide, Jaap J. Homan; van Son, Willem J.; Bakker, Stephan J. L.

    2009-01-01

    Background. Chronic low-grade inflammation is involved in chronic transplant dysfunction after renal transplantation. Procalcitonin (PCT), known to reflect microbial inflammation, may also reflect ongoing noninfectious chronic low-grade inflammation in organ parenchyma, including transplanted

  17. Accurate perioperative flow measurement of the portal vein and hepatic and renal artery: A role for preoperative MRI?

    Energy Technology Data Exchange (ETDEWEB)

    Vermeulen, Mechteld A.R., E-mail: mar.vermeulen@vumc.nl [Department of Surgery, VU University Medical Center, P.O. Box 7057, 1007 MB Amsterdam (Netherlands); Ligthart-Melis, Gerdien C., E-mail: g.ligthart-melis@vumc.nl [Department of Internal Medicine, Dietetics and Nutritional Sciences, VU University Medical Center, P.O. Box 7057, 1007 MB Amsterdam (Netherlands); Buijsman, René, E-mail: renebuysman@gmail.com [Department of Surgery, VU University Medical Center, P.O. Box 7057, 1007 MB Amsterdam (Netherlands); Siroen, Michiel P.C., E-mail: m.siroen6@upcmail.nl [Department of Surgery, VU University Medical Center, P.O. Box 7057, 1007 MB Amsterdam (Netherlands); Poll, Marcel C.G. van de, E-mail: mcg.vandepoll@ah.unimaas.nl [Department of Surgery, Maastricht University Medical Center, P.O. Box 5800, 6202 AZ Maastricht (Netherlands); Boelens, Petra G., E-mail: p.boelens@mumc.nl [Department of Surgery, Maastricht University Medical Center, P.O. Box 5800, 6202 AZ Maastricht (Netherlands); Dejong, Cornelis H.C., E-mail: chc.dejong@mumc.nl [Department of Surgery, Maastricht University Medical Center, P.O. Box 5800, 6202 AZ Maastricht (Netherlands); Schaik, Cors van, E-mail: c.vanschaik@vumc.nl [Department of Radiology, VU University Medical Center, P.O. Box 7057, 1007 MB Amsterdam (Netherlands); Hofman, Mark B.M., E-mail: mbm.hofman@vumc.nl [Department of Physics and Medical Technology, VU University Medical Center, P.O. Box 7057, 1007 MB Amsterdam (Netherlands); Leeuwen, Paul A.M. van, E-mail: pam.vleeuwen@vumc.nl [Department of Surgery, VU University Medical Center, P.O. Box 7057, 1007 MB Amsterdam (Netherlands)

    2012-09-15

    Background: Quantification of abdominal blood flow is essential for a variety of gastrointestinal and hepatic topics such as liver transplantation or metabolic flux measurement, but those need to be performed during surgery. It is not clear whether Duplex Doppler Ultrasound during surgery or MRI before surgery is the tool to choose. Objective: To examine whether preoperative evaluation of abdominal blood flow using MRI could prove to be a useful and reliable alternative for the perioperative sonographic approach. Methods: In this study portal and renal venous flow and hepatic arterial flow were sequentially quantified by preoperative MRI, preoperative and perioperative Duplex Doppler Ultrasound (DDUS). 55 Patients scheduled for major abdominal surgery were studied and methods and settings were compared. Additionally, average patient population values were compared. Results: Mean (±SD) plasmaflow measured by perioperative DDUS, preoperative DDUS and MRI, respectively was 433 ± 200/423 ± 162/507 ± 96 ml/min (portal vein); 96 ± 70/74 ± 41/108 ± 91 ml/min (hepatic artery); 248 ± 139/201 ± 118/219 ± 69 ml/min (renal vein). No differences between the different settings of DDUS measurement were detected. Equality of mean was observed for all measurements. Bland Altman Plots showed widespread margins. Hepatic arterial flow measurements correlated with each other, but portal and renal venous flow correlations were absent. Conclusions: Surgery and method (DDUS vs. MRI) do not affect mean flow values. Individual comparison is restricted due to wide range in measurements. Since MRI proves to be more reliable with respect to inter-observer variability, we recommend using mean MRI results in experimental setups.

  18. A microfluidic chip for blood plasma separation using electro-osmotic flow control

    International Nuclear Information System (INIS)

    Jiang, Hai; Weng, Xuan; Chon, Chan Hee; Wu, Xudong; Li, Dongqing

    2011-01-01

    In this paper, a microfluidic-based chip with two straight microchannels and five branch microchannels was designed and tested to separate blood plasma from a small sample of fresh human blood. The electro-osmotic flow method was used to control the separation of blood plasma. Blood cell removal and blood plasma extraction were realized in experiments. The efficiency of extracting blood plasma can be as high as 26%

  19. Effect of dialysis on cerebral blood flow in depressive end-stage renal disease patients

    International Nuclear Information System (INIS)

    Nam, Hyun-Yeol; Kim, Seong-Jang; Song, Sang-Heon

    2011-01-01

    The aim of this study was to investigate regional cerebral blood flow (rCBF) changes of end-stage renal disease (ESRD) patients with depressive symptoms during dialysis. Fourteen patients with ESRD underwent Tc-99m ethylcysteinate dimer (Tc-99m ECD) brain single photon emission computed tomography (SPECT) and were evaluated the severity of depressive mood at pre-dialytic period and at least 6 months after dialysis initiation. rCBF was analyzed using statistical parametric mapping (SPM) in brain SPECT image. The responder was defined as a decrease of ≥25% in Hamilton Depression Rating Scale (HDRS) score from baseline HDRS score. Pre-dialysis brain SPECT did not show any rCBF differences between responders and non-responders. The follow-up brain SPECT revealed a significant higher perfusion in left middle temporal gyrus of responder group when compared with non-responder (hemisphere coordinate X, Y, Z; -58, -2, -16, peak Z=3.36, p=0.046). In responder, a significant increase in rCBF was found in right parahippocampal gyrus (hemisphere coordinate X, Y, Z; 30, -40, -14, peak Z=3.51, p=0.043). In non-responder, there were significant decreases in rCBF in left superior frontal gyrus (hemisphere coordinate X, Y, Z; -22, 30, 42, peak Z=3.86, p=0.032) and right orbitofrontal cortex (hemisphere coordinate X, Y, Z; 10, 58, -6, peak Z=3.81, p=0.046). The present findings showed the characteristic patterns of rCBF changes in depressive ESRD patients having maintenance dialysis. Further investigations in brain blood flow and glucose metabolism are needed to elucidate the effect of dialysis itself and the difference of according to dialysis modality in patients having depression and ESRD. (author)

  20. Effect of Dielectric Barrier Discharge Plasma Actuators on Non-equilibrium Hypersonic Flows

    Science.gov (United States)

    2014-10-28

    results for MIG with the US3D code devel- oped at the University of Minnesota.61 US3D is an unstruc- tured CFD code for hypersonic flow solution used...Effect of dielectric barrier discharge plasma actuators on non-equilibrium hypersonic flows Ankush Bhatia,1 Subrata Roy,1 and Ryan Gosse2 1Applied...a cylindrical body in Mach 17 hypersonic flow is presented. This application focuses on using sinusoidal dielectric barrier discharge plasma actuators

  1. High-Flow Renal Arteriovenous Fistula Treated with the Amplatzer Vascular Plug: Implementation of an Arterial and Venous Approach

    International Nuclear Information System (INIS)

    Brountzos, Elias N.; Ptohis, Nikolaos; Grammenou-Pomoni, Maria; Panagiotou, Irini; Kelekis, Dimitrios; Gouliamos, Athanasios; Kelekis, Nikolaos

    2009-01-01

    We present a 28-year-old man with a large symptomatic arteriovenous fistula (AVF) treated with embolization using the Amplatzer vascular plug (AVP). Although embolization may be considered the first-line therapy in the treatment of AVFs, there is an inherent high risk of migration of the embolic agents into the venous and pulmonary circulations. This case is illustrative of the ease and safety of using this device in high-flow renal AVFs.

  2. A 3-MA compact-toroid-plasma-flow-switched plasma focus demonstration experiment on Shiva Star

    Energy Technology Data Exchange (ETDEWEB)

    Kiuttu, G F; Degnan, J H [Phillips Lab., Kirtland AFB, NM (United States). High Energy Sources Div.; Graham, J D [Maxwell Labs., Albuquerque, NM (United States); and others

    1997-12-31

    A novel dense plasma focus experiment using the Shiva Star capacitor bank is described. The experiment uses a compact toroid (CT) magnetized plasma flow switch (PFS) to initiate the focus implosion. The CT armature stably and reproducibly translates up to 3 MA from the vacuum feed region through coaxial electrodes to the gas puff central load. The inertia of the 1 mg CT and the work that must be done in compressing the internal magnetic fields during the translation provide a delay in current delivery to the pinch of 5 - 10 {mu}s, which matches the bank quarter cycle time relatively well. Effectiveness of the current delivery was monitored primarily by inductive probes in the PFS region, fast photography of the focus, and x-ray and neutron measurements of the pinch. K shell x-ray yields using neon gas were as high as 1 kJ, and 10{sup 8} neutrons were produced in a deuterium gas focus. (author). 4 figs., 10 refs.

  3. A 3-MA compact-toroid-plasma-flow-switched plasma focus demonstration experiment on Shiva Star

    International Nuclear Information System (INIS)

    Kiuttu, G.F.; Degnan, J.H.

    1996-01-01

    A novel dense plasma focus experiment using the Shiva Star capacitor bank is described. The experiment uses a compact toroid (CT) magnetized plasma flow switch (PFS) to initiate the focus implosion. The CT armature stably and reproducibly translates up to 3 MA from the vacuum feed region through coaxial electrodes to the gas puff central load. The inertia of the 1 mg CT and the work that must be done in compressing the internal magnetic fields during the translation provide a delay in current delivery to the pinch of 5 - 10 μs, which matches the bank quarter cycle time relatively well. Effectiveness of the current delivery was monitored primarily by inductive probes in the PFS region, fast photography of the focus, and x-ray and neutron measurements of the pinch. K shell x-ray yields using neon gas were as high as 1 kJ, and 10 8 neutrons were produced in a deuterium gas focus. (author). 4 figs., 10 refs

  4. Clinical significance of measurement of changes of plasma leptin and serum NPY levels after hemodialysis in patients with chronic renal failure

    International Nuclear Information System (INIS)

    Xia Zhengping

    2010-01-01

    Objective: To explore the clinical significance of changes of plasma leptin and serum NPY levels after hemodialysis in patients with chronic renal failure. Methods: Plasma leptin and serum NPY levels were measured with RIA both before and after hemodialysis in 31 patients with chronic renal failure as well as in 35 controls. Results: Before hemodialysis,plasma leptin and serum NPY levels were significantly higher in the patients than those in controls (P<0.01). After hemodialysis for 1 week the levels, though dropped markedly, still remained significantly higher than those in controls (P<0.05). Conclusion: The levels of leptin and NPY were significantly increased in patients with chronic renal failare. Hemodialysis could increase, the clearance rate of leptin and NPY and partially correct the levels with important clinical value. (authors)

  5. Renal scan

    Science.gov (United States)

    ... this page: //medlineplus.gov/ency/article/003790.htm Renal scan To use the sharing features on this ... anaphylaxis . Alternative Names Renogram; Kidney scan Images Kidney anatomy Kidney - blood and urine flow References Chernecky CC, ...

  6. Faster Blood Flow Rate Does Not Improve Circuit Life in Continuous Renal Replacement Therapy: A Randomized Controlled Trial.

    Science.gov (United States)

    Fealy, Nigel; Aitken, Leanne; du Toit, Eugene; Lo, Serigne; Baldwin, Ian

    2017-10-01

    To determine whether blood flow rate influences circuit life in continuous renal replacement therapy. Prospective randomized controlled trial. Single center tertiary level ICU. Critically ill adults requiring continuous renal replacement therapy. Patients were randomized to receive one of two blood flow rates: 150 or 250 mL/min. The primary outcome was circuit life measured in hours. Circuit and patient data were collected until each circuit clotted or was ceased electively for nonclotting reasons. Data for clotted circuits are presented as median (interquartile range) and compared using the Mann-Whitney U test. Survival probability for clotted circuits was compared using log-rank test. Circuit clotting data were analyzed for repeated events using hazards ratio. One hundred patients were randomized with 96 completing the study (150 mL/min, n = 49; 250 mL/min, n = 47) using 462 circuits (245 run at 150 mL/min and 217 run at 250 mL/min). Median circuit life for first circuit (clotted) was similar for both groups (150 mL/min: 9.1 hr [5.5-26 hr] vs 10 hr [4.2-17 hr]; p = 0.37). Continuous renal replacement therapy using blood flow rate set at 250 mL/min was not more likely to cause clotting compared with 150 mL/min (hazards ratio, 1.00 [0.60-1.69]; p = 0.68). Gender, body mass index, weight, vascular access type, length, site, and mode of continuous renal replacement therapy or international normalized ratio had no effect on clotting risk. Continuous renal replacement therapy without anticoagulation was more likely to cause clotting compared with use of heparin strategies (hazards ratio, 1.62; p = 0.003). Longer activated partial thromboplastin time (hazards ratio, 0.98; p = 0.002) and decreased platelet count (hazards ratio, 1.19; p = 0.03) were associated with a reduced likelihood of circuit clotting. There was no difference in circuit life whether using blood flow rates of 250 or 150 mL/min during continuous renal replacement therapy.

  7. Laboratory Observation of a Plasma-Flow-State Transition from Diverging to Stretching a Magnetic Nozzle.

    Science.gov (United States)

    Takahashi, Kazunori; Ando, Akira

    2017-06-02

    An axial magnetic field induced by a plasma flow in a divergent magnetic nozzle is measured when injecting the plasma flow from a radio frequency (rf) plasma source located upstream of the nozzle. The source is operated with a pulsed rf power of 5 kW, and the high density plasma flow is sustained only for the initial ∼100  μsec of the discharge. The measurement shows a decrease in the axial magnetic field near the source exit, whereas an increase in the field is detected at the downstream side of the magnetic nozzle. These results demonstrate a spatial transition of the plasma-flow state from diverging to stretching the magnetic nozzle, where the importance of both the Alfvén and ion Mach numbers is shown.

  8. Kelvin-Helmholtz instability for a bounded plasma flow in a longitudinal magnetic field

    International Nuclear Information System (INIS)

    Burinskaya, T. M.; Shevelev, M. M.; Rauch, J.-L.

    2011-01-01

    Kelvin-Helmholtz MHD instability in a plane three-layer plasma is investigated. A general dispersion relation for the case of arbitrarily orientated magnetic fields and flow velocities in the layers is derived, and its solutions for a bounded plasma flow in a longitudinal magnetic field are studied numerically. Analysis of Kelvin-Helmholtz instability for different ion acoustic velocities shows that perturbations with wavelengths on the order of or longer than the flow thickness can grow in an arbitrary direction even at a zero temperature. Oscillations excited at small angles with respect to the magnetic field exist in a limited range of wavenumbers even without allowance for the finite width of the transition region between the flow and the ambient plasma. It is shown that, in a low-temperature plasma, solutions resulting in kink-like deformations of the plasma flow grow at a higher rate than those resulting in quasi-symmetric (sausage-like) deformations. The transverse structure of oscillatory-damped eigenmodes in a low-temperature plasma is analyzed. The results obtained are used to explain mechanisms for the excitation of ultra-low-frequency long-wavelength oscillations propagating along the magnetic field in the plasma sheet boundary layer of the Earth’s magnetotail penetrated by fast plasma flows.

  9. Numerical investigation of aerodynamic flow actuation produced by surface plasma actuator on 2D oscillating airfoil

    Directory of Open Access Journals (Sweden)

    Minh Khang Phan

    2016-08-01

    Full Text Available Numerical simulation of unsteady flow control over an oscillating NACA0012 airfoil is investigated. Flow actuation of a turbulent flow over the airfoil is provided by low current DC surface glow discharge plasma actuator which is analytically modeled as an ion pressure force produced in the cathode sheath region. The modeled plasma actuator has an induced pressure force of about 2 kPa under a typical experiment condition and is placed on the airfoil surface at 0% chord length and/or at 10% chord length. The plasma actuator at deep-stall angles (from 5° to 25° is able to slightly delay a dynamic stall and to weaken a pressure fluctuation in down-stroke motion. As a result, the wake region is reduced. The actuation effect varies with different plasma pulse frequencies, actuator locations and reduced frequencies. A lift coefficient can increase up to 70% by a selective operation of the plasma actuator with various plasma frequencies and locations as the angle of attack changes. Active flow control which is a key advantageous feature of the plasma actuator reveals that a dynamic stall phenomenon can be controlled by the surface plasma actuator with less power consumption if a careful control scheme of the plasma actuator is employed with the optimized plasma pulse frequency and actuator location corresponding to a dynamic change in reduced frequency.

  10. Comparison of glomerular filtration rates by dynamic renal scintigraphy and dual-plasma sample clearance method in diabetic nephropathy

    International Nuclear Information System (INIS)

    Xie Peng; Huang Jianmin; Pan Liping; Liu Xiaomei; Wei Lingge; Gao Jianqing

    2010-01-01

    Objective: To evaluate the accuracy of renal scintigraphy for the estimation of glomerular filtration rates (dGFR) in patients with diabetic nephropathy as compared to the conventional dual-plasma sample clearance method (pscGFR). Methods: Forty-six patients with diabetic nephropathy underwent both dynamic renal scintigraphy and dual-plasma sample measurement after 99 Tc m -DTPA injection. Paired student t-test and correlation analysis were performed to compare dGFR and pscGFR (normalized to body surface area, 1.73 m -2 ). Results: The mean dGFR was higher than mean pscGFR ((51.08±26.78)ml·min -1 vs (44.06±29.43)ml·min -1 , t=4.209, P=0.000). The dGFR correlated with pscGFR (r=0.923, P=0.000) linearly (regression equation: pscGFR=1.015 x dGFR -7.773, F=254.656, P=0.000). Conclusions: dGFR correlated well with pscGFR. Although it could not absolutely replace the latter in patients with diabetic nephropathy, dGFR could reasonably evaluate the filtration function for these patients. (authors)

  11. Modification of structural materials by pulsed plasma flows

    International Nuclear Information System (INIS)

    Bandura, A.N.; Garkusha, I.E.; Byrka, O.V.; Makhlaj, V.A.

    2011-01-01

    Features of surface modification and materials alloying from gas and metallic plasma as a result of the plasma ions mixing with the steel substrate in liquid phase are investigated in this paper.The experiments have been carried out with pulsed plasma gun, which generates plasma streams with ion energy up to 2 keV, plasma density 2x10 14 cm -3 , average specific power of 10 MW/cm 2 and plasma energy density in the range of (5-40) J/cm 2 . The nitrogen, helium, other gases and their mixtures can be used as working gases. The regime of plasma treatment was chosen with variation of both the discharge voltage and the distance of the material surface from the gun output. Modification of thin (0.5-2 µm) PVD coatings of MoN, C+W, TiN, TiC, Cr, Cr+CrN and others by the pulsed plasma streams are analyzed also. It is shown that pulsed plasma treatment results in essential improvement of physical and mechanical properties of exposed materials. For example, microhardness of samples with Cr coating, after plasma treatment, increased in 2,5 times. Mechanisms of surface modification of a different alloys and coating irradiated with pulsed plasma streams of different ions are discussed. (authors)

  12. Tratamento endovascular de aneurisma da artéria renal por embolização com micromolas preservando o fluxo sangüíneo renal: relato de caso Endovascular treatment of renal artery aneurysm using microcoil embolization and renal blood flow preservation: case report

    Directory of Open Access Journals (Sweden)

    Marco Aurélio Cardozo

    2007-06-01

    Full Text Available O tratamento endovascular da doença aneurismática da artéria renal tem sido, cada vez mais, aceito como uma alternativa à cirurgia convencional, especialmente em casos de aneurismas complexos intra-parenquimatosos ou que comprometam a bifurcação da artéria renal. Os autores relatam a experiência do tratamento endovascular de uma paciente com aneurisma sacular da bifurcação da artéria renal direita, associado à hipertensão renovascular de difícil controle. Foi realizada a cateterização seletiva da artéria renal, com a inserção de micromolas no saco aneurismático. O aneurisma foi completamente ocluído com preservação total do fluxo sanguíneo renal. A evolução clínica foi satisfatória com redução significativa das medicações anti-hipertensivas. A angio-tomografia de controle, após o oitavo mês do procedimento, confirmou o sucesso do tratamento.Endovascular treatment of renal artery aneurysmal disease has been increasingly accepted as an alternative to conventional surgery, especially in cases of renal artery bifurcation or complex intrarenal aneurysms. The authors report a case of endovascular treatment of a saccular aneurysm of the right renal artery bifurcation associated with poorly controlled renovascular hypertension. Selective catheterization of the renal artery was performed and microcoils were inserted into the aneurysmal sac. The aneurysm was completely obliterated with total preservation of renal blood flow. Clinical evolution was satisfactory with significant reduction in anti-hypertensive drugs. Control tomographic angiography, after eight months, confirmed treatment success.

  13. A new facility for studying plasma interacting with flowing liquid lithium surface

    International Nuclear Information System (INIS)

    Cao, X.; Ou, W.; Tian, S.; Wang, C.; Zhu, Z.; Wang, J.; Gou, F.; Yang, D.; Chen, S.

    2014-01-01

    A new facility to study plasmas interacting with flowing liquid lithium surface was designed and is constructing in Sichuan University. The integrated setup includes the liquid lithium circulating part and linear high density plasma generator. The circulating part is consisted of main loop, on-line monitor system, lithium purification system and temperature programmed desorption system. In our group a linear high density plasma generator was built in 2012. Three coils were mounted along the vessel to produce an axial magnetic field inside. The magnetic field strength is up to 0.45 T and work continuously. Experiments on plasmas interacting with free flowing liquid lithium surface will be performed

  14. Levels of cholesteryl esters and other lipids in the plasma of patientswith end-stage renal failure

    International Nuclear Information System (INIS)

    Gillett, Michael P.T.; Obineche, Enyioma N.; Lakhani, Mohammad S.; Abdulle, Abdishakur M.; Amirlak, I.; Al-Rukhaimi, M.; Suleiman, Mustafa N.

    2001-01-01

    The importance of plasma lipid abnormalities in chronic renal failure(CRF) is well recognized, but surprisingly little attention has been given tothe study of some plasma lipid fractions, including cholesteryl esters (CE)and phospholipids, which might be expected to be important factors in thepathogenesis of disease. Fasting blood samples were taken from 25 controlsubjects and 53 CRF patients (29 predialysis and 24 on Hemodialysis). Sampleswere analyzed for urea nitrogen, creatinine, triacyglycerols, total andindividuals phospholipids, total and free cholesterol, as well as cholesterolbound to be very low-, and high- density lipoproteins (VDL, LDL and HDL).Plasma CE was calculated and expressed as a percentage of total cholesterol.Over half of the patients had CE levels more than two standard deviationsbelow the control value. In this subgroup of low CE patients, total LDL- andHDL-cholesterol levels were also significantly lower than for controls, whilelevels of phosphatidylcholine and lysophosphatidylcholine were decreased andincreased, respectively. In patients with high CE, no significant lipidabnormalities were observed. In this study, CE was an excellent marker forlipid disturbances-if CE was high, then the other lipid fractions wereabnormal. The changes noted appear to be consequences of or related todeficiency of the plasma enzyme lecithin-cholesterol acyltransferase. (author)

  15. Role of Mas receptor in renal blood flow response to angiotensin (1-7) in male and female rats.

    Science.gov (United States)

    Nematbakhsh, Mehdi; Safari, Tahereh

    2014-01-01

    Epidemiologic and clinical studies have shown that progression of renal disease in male is faster than that in female. However, the exact mechanisms are not well recognized. Angiotensin (1-7) (Ang 1-7) receptor, called "Mas", is an element in the depressor arm of renin angiotensin system (RAS), and its expression is enhanced in females. We test the hypothesis that Mas receptor (MasR) blockade (A779) attenuates renal blood flow (RBF) in response to infusion of graded doses of Ang 1-7 in female rats. Male and female Wistar rats were anesthetized and catheterized. Then, the mean arterial pressure (MAP), RBF, and controlled renal perfusion pressure (RPP) responses to infusion of graded doses of Ang 1-7 (100-1000 ng/kg/min i.v.) with and without A779 were measured in the animals. Basal MAP, RPP, RBF, and renal vascular resistance (RVR) were not significantly different between the two groups. After Ang 1-7 administration, RPP was controlled at a constant level. However, RBF increased in a dose-related manner in response to Ang 1-7 infusion in both male and female rats (Pdoserenal diseases.

  16. Enhanced nonlinear iterative techniques applied to a nonequilibrium plasma flow

    International Nuclear Information System (INIS)

    Knoll, D.A.

    1998-01-01

    The authors study the application of enhanced nonlinear iterative methods to the steady-state solution of a system of two-dimensional convection-diffusion-reaction partial differential equations that describe the partially ionized plasma flow in the boundary layer of a tokamak fusion reactor. This system of equations is characterized by multiple time and spatial scales and contains highly anisotropic transport coefficients due to a strong imposed magnetic field. They use Newton's method to linearize the nonlinear system of equations resulting from an implicit, finite volume discretization of the governing partial differential equations, on a staggered Cartesian mesh. The resulting linear systems are neither symmetric nor positive definite, and are poorly conditioned. Preconditioned Krylov iterative techniques are employed to solve these linear systems. They investigate both a modified and a matrix-free Newton-Krylov implementation, with the goal of reducing CPU cost associated with the numerical formation of the Jacobian. A combination of a damped iteration, mesh sequencing, and a pseudotransient continuation technique is used to enhance global nonlinear convergence and CPU efficiency. GMRES is employed as the Krylov method with incomplete lower-upper (ILU) factorization preconditioning. The goal is to construct a combination of nonlinear and linear iterative techniques for this complex physical problem that optimizes trade-offs between robustness, CPU time, memory requirements, and code complexity. It is shown that a mesh sequencing implementation provides significant CPU savings for fine grid calculations. Performance comparisons of modified Newton-Krylov and matrix-free Newton-Krylov algorithms will be presented

  17. Advanced plasma flow simulations of cathodic-arc and ferroelectric plasma sources for neutralized drift compression experiments

    Directory of Open Access Journals (Sweden)

    Adam B. Sefkow

    2008-07-01

    Full Text Available Large-space-scale and long-time-scale plasma flow simulations are executed in order to study the spatial and temporal evolution of plasma parameters for two types of plasma sources used in the neutralized drift compression experiment (NDCX. The results help assess the charge neutralization conditions for ion beam compression experiments and can be employed in more sophisticated simulations, which previously neglected the dynamical evolution of the plasma. Three-dimensional simulations of a filtered cathodic-arc plasma source show the coupling efficiency of the plasma flow from the source to the drift region depends on geometrical factors. The nonuniform magnetic topology complicates the well-known general analytical considerations for evaluating guiding-center drifts, and particle-in-cell simulations provide a self-consistent evaluation of the physics in an otherwise challenging scenario. Plasma flow profiles of a ferroelectric plasma source demonstrate that the densities required for longitudinal compression experiments involving ion beams are provided over the drift length, and are in good agreement with measurements. Simulations involving azimuthally asymmetric plasma creation conditions show that symmetric profiles are nevertheless achieved at the time of peak on-axis plasma density. Also, the ferroelectric plasma expands upstream on the thermal expansion time scale, and therefore avoids the possibility of penetration into the acceleration gap and transport sections, where partial neutralization would increase the beam emittance. Future experiments on NDCX will investigate the transverse focusing of an axially compressing intense charge bunch to a sub-mm spot size with coincident focal planes using a strong final-focus solenoid. In order to fill a multi-tesla solenoid with the necessary high-density plasma for beam charge neutralization, the simulations predict that supersonically injected plasma from the low-field region will penetrate and

  18. Ideal stability of cylindrical plasma in the presence of mass flow

    International Nuclear Information System (INIS)

    Bondeson, A.; Iacono, R.

    1988-11-01

    The ideal stability of cylindrical plasma with mass flows is investigated using the guiding centre plasma (GCP) model of Grad. For rotating plasmas, the kinetic treatment of the parallel motion in GCP gives significantly different results than fluid models, where the pressures are obtained from equations of state. In particular, GCP removes the resonance with slow magnetoacoustic waves and the loss of stability that results in magnetohydrodynamics (MHD) for near-soni flows. Because of the strong kinetic damping of the sound waves in an isothermal plasma, the slow waves have little influence on plasma stability in GCP at low β. In the large aspect ratio, low-β tokamak ordering, Alfvenic flows are needed to change the ideal GCP stability significantly. At lowest order in the inverse aspect ratio, flow can be favorable or unfavorable for stability of local modes depending on the profiles, but external kinks are always destilized by flow if the velocity vanishes at the edge. For high-β, reversed field pinch equilibria, numerical computations show that flow can be stabilizing for local modes, but external modes are destabilized by flow. It is shown that in three dimensions, the MHD equilibrium problem becomes hyperbolic for arbitrarily small flows across the magnetic field, whereas in GCP the equilibrium remains elliptic for sub-Alfvenic flows. (author) 7 figs., 1 tab, 32 refs

  19. Numerical and Experimental Investigation of Turbulent Transport Control via Shaping of Radial Plasma Flow Profiles

    International Nuclear Information System (INIS)

    Gilmore, Mark Allen

    2017-01-01

    Turbulence, and turbulence-driven transport are ubiquitous in magnetically confined plasmas, where there is an intimate relationship between turbulence, transport, instability driving mechanisms (such as gradients), plasma flows, and flow shear. Though many of the detailed physics of the interrelationship between turbulence, transport, drive mechanisms, and flow remain unclear, there have been many demonstrations that transport and/or turbulence can be suppressed or reduced via manipulations of plasma flow profiles. This is well known in magnetic fusion plasmas [e.g., high confinement mode (H-mode) and internal transport barriers (ITB's)], and has also been demonstrated in laboratory plasmas. However, it may be that the levels of particle transport obtained in such cases [e.g. H-mode, ITB's] are actually lower than is desirable for a practical fusion device. Ideally, one would be able to actively feedback control the turbulent transport, via manipulation of the flow profiles. The purpose of this research was to investigate the feasibility of using both advanced model-based control algorithms, as well as non-model-based algorithms, to control cross-field turbulence-driven particle transport through appropriate manipulation of radial plasma flow profiles. The University of New Mexico was responsible for the experimental portion of the project, while our collaborators at the University of Montana provided plasma transport modeling, and collaborators at Lehigh University developed and explored control methods.

  20. Numerical and Experimental Investigation of Turbulent Transport Control via Shaping of Radial Plasma Flow Profiles

    Energy Technology Data Exchange (ETDEWEB)

    Gilmore, Mark Allen [Univ. of New Mexico, Albuquerque, NM (United States)

    2017-02-05

    Turbulence, and turbulence-driven transport are ubiquitous in magnetically confined plasmas, where there is an intimate relationship between turbulence, transport, instability driving mechanisms (such as gradients), plasma flows, and flow shear. Though many of the detailed physics of the interrelationship between turbulence, transport, drive mechanisms, and flow remain unclear, there have been many demonstrations that transport and/or turbulence can be suppressed or reduced via manipulations of plasma flow profiles. This is well known in magnetic fusion plasmas [e.g., high confinement mode (H-mode) and internal transport barriers (ITB’s)], and has also been demonstrated in laboratory plasmas. However, it may be that the levels of particle transport obtained in such cases [e.g. H-mode, ITB’s] are actually lower than is desirable for a practical fusion device. Ideally, one would be able to actively feedback control the turbulent transport, via manipulation of the flow profiles. The purpose of this research was to investigate the feasibility of using both advanced model-based control algorithms, as well as non-model-based algorithms, to control cross-field turbulence-driven particle transport through appropriate manipulation of radial plasma flow profiles. The University of New Mexico was responsible for the experimental portion of the project, while our collaborators at the University of Montana provided plasma transport modeling, and collaborators at Lehigh University developed and explored control methods.

  1. Endogenous Plasma Erythropoietin, Cardiovascular Mortality and All-Cause Mortality in Renal Transplant Recipients

    NARCIS (Netherlands)

    Sinkeler, S. J.; Zelle, D. M.; van der Heide, J. J. Homan; Gans, R. O. B.; Navis, G.; Bakker, S. J. L.

    Cardiovascular disease (CVD) is the main cause of mortality in renal transplant recipients (RTR). Classical factors only partly explain the excess risk. We hypothesized that high EPO-a marker for inflammation, angiogenesis and hypoxia-is associated with CVD in RTR. A total of 568 RTR (51 +/- 12

  2. Endogenous plasma erythropoietin, cardiovascular mortality and all-cause mortality in renal transplant recipients

    NARCIS (Netherlands)

    Sinkeler, S. J.; Zelle, D. M.; Homan van der Heide, J. J.; Gans, R. O. B.; Navis, G.; Bakker, S. J. L.

    2012-01-01

    Cardiovascular disease (CVD) is the main cause of mortality in renal transplant recipients (RTR). Classical factors only partly explain the excess risk. We hypothesized that high EPO--a marker for inflammation, angiogenesis and hypoxia--is associated with CVD in RTR. A total of 568 RTR (51±12 years;

  3. Plasma Lipoprotein(a Levels and Atherosclerotic Renal Artery Stenosis in Hypertensive Patients

    Directory of Open Access Journals (Sweden)

    Cristiana Catena

    2015-03-01

    Full Text Available Background/Aims: The contribution of emergent cardiovascular risk factors to atherosclerotic renal artery stenosis (ARAS is debated. We investigated the relationship of lipoprotein(a and prothrombotic factors with ARAS in hypertension. Methods: In 50 hypertensive patients with angiographic evidence of ARAS and 58 hypertensive patients who had comparable cardiovascular risk factor burden but no evidence of renovascular disease, we measured renal function, lipoprotein(a, homocysteine, and hemostatic-fibrinolytic markers. Results: Patients with ARAS were more frequently smokers and had longer duration of hypertension, heavier antihypertensive treatment, and worse renal function than controls. Lipoprotein(a was higher in patients with ARAS than controls, whereas no differences were found in homocysteine and all hemostatic variables. Multivariate analysis showed that lipoprotein(a was associated with ARAS independent of other confounders including renal function and history of coronary heart, cerebrovascular, and peripheral artery disease. Conclusion: Lipoprotein(a might contribute to the development of ARAS and detection of elevated levels of this lipoprotein could raise the suspicion of renovascular disease in patients with high blood pressure.

  4. Understanding the SOL flow in L-mode plasma on divertor tokamaks, and its influence on the plasma transport

    International Nuclear Information System (INIS)

    Asakura, Nobuyuki

    2007-01-01

    Significant progress has been made in understanding the driving mechanisms in SOL mass transport along the magnetic field lines (SOL flow). SOL flow measurements by Mach probes and impurity plume have been performed in L-mode plasma at various poloidal locations in divertor tokamaks. All results showed common SOL flow patterns: subsonic flow with parallel Mach number (M parallel ) of 0.2-1 was generated from the Low-Field-Side (LFS) SOL to the High-Field-Side (HFS) divertor for the ion ∇B drift towards the divertor. The SOL flow pattern was formed mainly by LFS-enhanced asymmetry in diffusion and by classical drifts. In addition, divertor detachment and/or intense puffing-and-pump enhanced the HFS SOL flow. Most codes have incorporated drift effects, and asymmetric diffusion was modelled to simulate the fast SOL flow. Influences of the fast SOL flow on the impurity flow in the SOL, shielding from core plasma, and deposition profile, were directly observed in experiments

  5. Investigations on interactions between the flowing liquid lithium limiter and plasmas

    International Nuclear Information System (INIS)

    Ren, J.; Zuo, G.Z.; Hu, J.S.; Sun, Z.; Li, J.G.; Zakharov, L.E.; Ruzic, D.N.; Xu, W.Y.

    2016-01-01

    Two different designs of flowing liquid lithium limiter were first tested for power exhaust and particle removal in HT-7 in 2012 autumn campaign. During the experiments, the reliability and compatibility of the limiters within Tokamak were experimentally demonstrated, and some positive results were achieved. It was found that the flowing liquid lithium limiter was effective for suppressing H concentration and led to a low ratio of H/(H + D). O impurity was slightly decreased by using limiters as well as when using a Li coating. A significant increase of the wall retention ratio was also observed which resulted from the outstanding D particles pumping ability of flowing liquid lithium limiters. The strong interaction between plasma and lithium surface could cause lithium ejection into plasma and lead to disruptions. The stable plasmas produced by uniform Li flow were in favor of lithium control. While the limiters were applied with a uniform Li flow, the normal plasma was easy to be obtained, and the energy confinement time increased from ∼0.025 s to 0.04 s. Furthermore, it was encouraging to note that the application of flowing liquid lithium limiters could further improve the confinement of plasma by ∼10% on the basis of Li coating. These remarkable results will help for the following design of flowing liquid lithium limiter in EAST to improve the plasma operation.

  6. Relaxation of potential, flows, and density in the edge plasma of Castor tokamak

    International Nuclear Information System (INIS)

    Hron, M.; Weinzettl, V.; Dufkova, E.; Duran, I.; Stoeckel, J.; Hidalgo, C.

    2004-01-01

    Decay times of plasma flows and plasma profiles have been measured after a sudden biasing switch-off in experiments on the Castor tokamak. A biased electrode has been used to polarize the edge plasma. The edge plasma potential and flows have been characterized by means of Langmuir and Mach probes, the radiation was measured using an array of bolometers. Potential profiles and poloidal flows can be well fitted by an exponential decay time in the range of 10 - 30 μs when the electrode biasing is turned off in the Castor tokamak. The radiation shows a slower time scale (about 1 ms), which is linked to the evolution in the plasma density and particle confinement. (authors)

  7. Characteristics of an under-expanded supersonic flow in arcjet plasmas

    Science.gov (United States)

    Namba, Shinichi; Shikama, Taiichi; Sasano, Wataru; Tamura, Naoki; Endo, Takuma

    2018-06-01

    A compact apparatus to produce arcjet plasma was fabricated to investigate supersonic flow dynamics. Periodic bright–dark emission structures were formed in the arcjets, depending on the plasma source and ambient gas pressures in the vacuum chamber. A directional Langmuir probe (DLP) and emission spectroscopy were employed to characterize plasma parameters such as the Mach number of plasma flows and clarify the mechanism for the generation of the emission pattern. In particular, in order to investigate the influence of the Mach number on probe size, we used two DLPs of different probe size. The results indicated that the arcjets could be classified into shock-free expansion and under-expansion, and the behavior of plasma flow could be described by compressible fluid dynamics. Comparison of the Langmuir probe results with emission and laser absorption spectroscopy showed that the small diameter probe was reliable to determine the Mach number, even for the supersonic jet.

  8. Cross-tail velocity component in the plasma sheet fast flows

    Directory of Open Access Journals (Sweden)

    N. P. Dmitrieva

    2008-06-01

    Full Text Available The flux transfer in the magnetotail plasma sheet is mainly provided by the tail-aligned fast plasma flows (Bursty Bulk Flows – BBFs. In this paper we study the events with a large cross-tail velocity component, including their occurrence and relationship to the standard BBFs. We found out that a significant part of large Vy events are a subgroup connected with the BBFs propagation. The maximal deviation of the velocity vector from the X direction (about 40–50 degrees, on average is observed near the BBFs' leading front in the sheath, where the fast flow interacts with surrounding plasma. The average variation of the velocity direction in the vicinity of the BBF resembles a plasma vortex. Our results support the model, in which the BBF represents a polarized, bubble-like flux tube, propagating through the plasma sheet.

  9. Hepatic and renal function with successful long-term support on a continuous flow left ventricular assist device.

    Science.gov (United States)

    Deo, Salil V; Sharma, Vikas; Altarabsheh, Salah E; Hasin, Tal; Dillon, John; Shah, Ishan K; Durham, Lucian A; Stulak, John M; Daly, Richard C; Joyce, Lyle D; Park, Soon J

    2014-03-01

    Data regarding the long-term clinical effects of a continuous flow left ventricular assist device (CF-LVAD) on hepato-renal function is limited. Hence our aim was to assess changes in hepato-renal function over a one-year period in patients supported on a CF-LVAD. During the study period 126 patients underwent CF-LVAD implant. Changes in hepato-renal laboratory parameters were studied in 61/126 patients successfully supported on a CF-LVAD for period of one year. A separate cohort of a high-risk group (HCrB) of patients (56/126) with a serum creat>1.9 mg/dL (168 μmol/L) (75th percentile) or a serum bil>1.5 mg/dL (25.65 μmol/L) (75th percentile) was created. Changes in serum creatinine and bilirubin were analysed at regular intervals for this group along with the need for renal replacement therapy. Baseline creatinine and blood urea nitrogen (BUN) for the entire cohort was 1.4[1.2,1.9 mg/dL] [123.7(106,168) μmol/L) and 27[20,39.5 mg/dL] [9.6(7.1,14.1) mmol/L] respectively. After an initial reduction at the end of one month [1(0.8,1.2) mg/dL; 88(70,105) μmol/L] (passist device support for one year. High-risk patients demonstrate a higher 30-day mortality and temporary need for renal replacement therapy. Yet even in this cohort, improvement is present over a period of one year on the device, with a minimal need for permanent haemodialysis. Copyright © 2013 Australian and New Zealand Society of Cardiac and Thoracic Surgeons (ANZSCTS) and the Cardiac Society of Australia and New Zealand (CSANZ). Published by Elsevier B.V. All rights reserved.

  10. Nonlinear inertial Alfven waves in plasmas with sheared magnetic field and flow

    International Nuclear Information System (INIS)

    Chen Yinhua; Wang Ge; Tan Liwei

    2004-01-01

    Nonlinear equations describing inertial Alfven waves in plasmas with sheared magnetic field and flow are derived. For some specific parameters chosen, authors have found a new type of electromagnetic coherent structures in the tripolar vortex-like form

  11. Energy Flow in Dense Off-Equilibrium Plasma

    Science.gov (United States)

    2016-07-15

    brings the electron density and light emission into LTE at the measured spectral temperature while leaving the ions cold. Because of their large mass... measurements of ionization potential lowering and collision times indense plasmas, allowing us to distinguish between competing dense-plasma models...Hydrodynamic analysis of shockwaves generated by sparks yielded similar measurements ina different, more accessible system. Ultra-fast observations

  12. Scaling relations for plasma production and acceleration of rotating plasma flows

    International Nuclear Information System (INIS)

    Ikehata, Takashi; Tanabe, Toshio; Mase, Hiroshi; Sekine, Ryusuke; Hasegawa, Kazuyuki.

    1989-01-01

    Scaling relations are investigated theoretically and experimentally of the plasma production and acceleration in the rotating plasma gun which has been developed as a new means of plasma centrifuge. Two operational modes: the gas-discharge mode for gaseous elements and the vacuum-discharge mode for solid elements are studied. Relations of the plasma density and velocities to the discharge current and the magnetic field are derived. The agreement between experiment and theory is quite well. It is found that fully-ionized rotating plasmas produced in the gas-discharge mode is most advantageous to realize efficient plasma centrifuge. (author)

  13. PIC Modeling of Argon Plasma Flow in MNX

    Science.gov (United States)

    Cohen, Samuel; Sefkow, Adam

    2007-11-01

    A linear helicon-heated plasma device - the Magnetic Nozzle Experiment (MNX) at the Princeton Plasma Physics Laboratory - is used for studies of the formation of strong electrostatic double layers near mechanical and magnetic apertures and the acceleration of plasma ions into supersonic directed beams. In order to characterize the role of the aperture and its involvement with ion acceleration, detailed particle-in-cell simulations are employed to study the effects of the surrounding boundary geometry on the plasma dynamics near the aperture region, within which the transition from a collisional to collisionless regime occurs. The presence of a small superthermal electron population is examined, and the model includes a background neutral population which can be ionized by energetic electrons. By self-consistently evaluating the temporal evolution of the plasma in the vicinity of the aperture, the formation mechanism of the double layer is investigated.

  14. Statistical study of high-latitude plasma flow during magnetospheric substorms

    Directory of Open Access Journals (Sweden)

    G. Provan

    2004-11-01

    Full Text Available We have utilised the near-global imaging capabilities of the Northern Hemisphere SuperDARN radars, to perform a statistical superposed epoch analysis of high-latitude plasma flows during magnetospheric substorms. The study involved 67 substorms, identified using the IMAGE FUV space-borne auroral imager. A substorm co-ordinate system was developed, centred on the magnetic local time and magnetic latitude of substorm onset determined from the auroral images. The plasma flow vectors from all 67 intervals were combined, creating global statistical plasma flow patterns and backscatter occurrence statistics during the substorm growth and expansion phases. The commencement of the substorm growth phase was clearly observed in the radar data 18-20min before substorm onset, with an increase in the anti-sunward component of the plasma velocity flowing across dawn sector of the polar cap and a peak in the dawn-to-dusk transpolar voltage. Nightside backscatter moved to lower latitudes as the growth phase progressed. At substorm onset a flow suppression region was observed on the nightside, with fast flows surrounding the suppressed flow region. The dawn-to-dusk transpolar voltage increased from ~40kV just before substorm onset to ~75kV 12min after onset. The low-latitude return flow started to increase at substorm onset and continued to increase until 8min after onset. The velocity flowing across the polar-cap peaked 12-14min after onset. This increase in the flux of the polar cap and the excitation of large-scale plasma flow occurred even though the IMF Bz component was increasing (becoming less negative during most of this time. This study is the first to statistically prove that nightside reconnection creates magnetic flux and excites high-latitude plasma flow in a similar way to dayside reconnection and that dayside and nightside reconnection, are two separate time-dependent processes.

  15. Hybrid simulations of current-carrying instabilities in Z-pinch plasmas with sheared axial flow

    International Nuclear Information System (INIS)

    Sotnikov, Vladimir I.; Makhin, Volodymyr; Bauer, Bruno S.; Hellinger, Petr; Travnicek, Pavel; Fiala, Vladimir; Leboeuf, Jean-Noel

    2002-01-01

    The development of instabilities in z-pinch plasmas has been studied with three-dimensional (3D) hybrid simulations. Plasma equilibria without and with sheared axial flow have been considered. Results from the linear phase of the hybrid simulations compare well with linear Hall magnetohydrodynamics (MHD) calculations for sausage modes. The hybrid simulations show that sheared axial flow has a stabilizing effect on the development of both sausage and kink modes

  16. Plasma flow velocity measurements using a modulated Michelson interferometer

    International Nuclear Information System (INIS)

    Howard, J.

    1997-01-01

    This paper discusses the possibility of flow velocity reconstruction using passive spectroscopic techniques. We report some preliminary measurements of the toroidal flow velocity of hydrogen atoms in the RTP tokamak using a phase modulated Michelson interferometer. (orig.)

  17. Plasma-liquid system with reverse vortex flow of 'tornado' type (TORNADO-LE)

    International Nuclear Information System (INIS)

    Nedybalyuk, O.A.; Chernyak, V.Ya.; Olszewski, S.V.

    2010-01-01

    The results of experimental investigations of the plasma in plasma-liquid system with reverse vortex flow of 'tornado' type are presented. Volt-ampere characteristic of discharge in the current range from 200 to 400 mA were measured. Emission spectra of plasma in range from 200 to 1100 nm were measured. Excitation temperatures (electronic T e * , vibrational T v * and rotational T r * ) were obtained. Emission spectra of hydroxyl OH were calculated.

  18. Dynamic and Stagnating Plasma Flow Leading to Magnetic-Flux-Tube Collimation

    International Nuclear Information System (INIS)

    You, S.; Yun, G.S.; Bellan, P.M.

    2005-01-01

    Highly collimated, plasma-filled magnetic-flux tubes are frequently observed on galactic, stellar, and laboratory scales. We propose that a single, universal magnetohydrodynamic pumping process explains why such collimated, plasma-filled magnetic-flux tubes are ubiquitous. Experimental evidence from carefully diagnosed laboratory simulations of astrophysical jets confirms this assertion and is reported here. The magnetohydrodynamic process pumps plasma into a magnetic-flux tube and the stagnation of the resulting flow causes this flux tube to become collimated

  19. BRIEF COMMUNICATION: On the drift kinetic equation driven by plasma flows

    Science.gov (United States)

    Shaing, K. C.

    2010-07-01

    A drift kinetic equation that is driven by plasma flows has previously been derived by Shaing and Spong 1990 (Phys. Fluids B 2 1190). The terms that are driven by particle speed that is parallel to the magnetic field B have been neglected. Here, such terms are discussed to examine their importance to the equation and to show that these terms do not contribute to the calculations of plasma viscosity in large aspect ratio toroidal plasmas, e.g. tokamaks and stellarators.

  20. Modeling and experiments on differential pumping in linear plasma generators operating at high gas flows

    NARCIS (Netherlands)

    Eck, van H.J.N.; Koppers, W.R.; Rooij, van G.J.; Goedheer, W.J.; Engeln, R.A.H.; Schram, D.C.; Lopes Cardozo, N.J.; Kleyn, A.W.

    2009-01-01

    The direct simulation Monte Carlo (DSMC) method was used to investigate the efficiency of differential pumping in linear plasma generators operating at high gas flows. Skimmers are used to separate the neutrals from the plasma beam, which is guided from the source to the target by a strong axial

  1. The rebirth of interest in renal tubular function.

    Science.gov (United States)

    Lowenstein, Jerome; Grantham, Jared J

    2016-06-01

    The measurement of glomerular filtration rate by the clearance of inulin or creatinine has evolved over the past 50 years into an estimated value based solely on plasma creatinine concentration. We have examined some of the misconceptions and misunderstandings of the classification of renal disease and its course, which have followed this evolution. Furthermore, renal plasma flow and tubular function, which in the past were estimated by the clearance of the exogenous aryl amine, para-aminohippurate, are no longer measured. Over the past decade, studies in experimental animals with reduced nephron mass and in patients with reduced renal function have identified small gut-derived, protein-bound uremic retention solutes ("uremic toxins") that are poorly filtered but are secreted into the lumen by organic anion transporters (OATs) in the proximal renal tubule. These are not effectively removed by conventional hemodialysis or peritoneal dialysis. Residual renal function, urine produced in patients with advanced renal failure or undergoing dialysis treatment, may represent, at least in part, secretion of fluid and uremic toxins, such as indoxyl sulfate, mediated by proximal tubule OATs and might serve as a useful survival function. In light of this new evidence of the physiological role of proximal tubule OATs, we suggest that measurement of renal tubular function and renal plasma flow may be of considerable value in understanding and managing chronic kidney disease. Data obtained in normal subjects indicate that renal plasma flow and renal tubular function might be measured by the clearance of the endogenous aryl amine, hippurate. Copyright © 2016 the American Physiological Society.

  2. Study of the renal function in diabetic patients by 99sup(m)Tc-DTPA and 131I-Hippuran

    International Nuclear Information System (INIS)

    Silva, N.C. da.

    1981-01-01

    Twenty-six patients with diabetes in different stages were studied by radioisotopic techniques in an attempt to detect early alterations of renal function. Renal scintillography, 99 sup(m)Tc-DTPA glomerular filtration rate, renogram and 131 I-Hippuran effective renal plasma flow were the techniques employed. Renal evaluation was filled out by biochemical analysis of plasmatic urea and creatinine, 24 h-proteinuria and funduscopy of patients. The renal disease of diabetic patient is a result of the sum of many factors and subclinical functional alterations that appear can be ascribed to reversible hemodynamic alterations, such as decrease of plasma flow with increase of ultrafiltrated plasma fraction and of glomerular filtration. Mechanisms that lead to these alterations are not yet stablished. This work suggests that the diabetic patients well metabolic compensated present less incidence of degenerative complications, among them renal lesions. (Author) [pt

  3. Asymmetrical flow field-flow fractionation coupled with multiple detections: A complementary approach in the characterization of egg yolk plasma.

    Science.gov (United States)

    Dou, Haiyang; Li, Yueqiu; Choi, Jaeyeong; Huo, Shuying; Ding, Liang; Shen, Shigang; Lee, Seungho

    2016-09-23

    The capability of asymmetrical flow field-flow fractionation (AF4) coupled with UV/VIS, multiangle light scattering (MALS) and quasi-elastic light scattering (QELS) (AF4-UV-MALS-QELS) for separation and characterization of egg yolk plasma was evaluated. The accuracy of hydrodynamic radius (Rh) obtained from QELS and AF4 theory (using both simplified and full expression of AF4 retention equations) was discussed. The conformation of low density lipoprotein (LDL) and its aggregates in egg yolk plasma was discussed based on the ratio of radius of gyration (Rg) to Rh together with the results from bio-transmission electron microscopy (Bio-TEM). The results indicate that the full retention equation is more relevant than simplified version for the Rh determination at high cross flow rate. The Rh from online QELS is reliable only at a specific range of sample concentration. The effect of programmed cross flow rate (linear and exponential decay) on the analysis of egg yolk plasma was also investigated. It was found that the use of an exponentially decaying cross flow rate not only reduces the AF4 analysis time of the egg yolk plasma, but also provides better resolution than the use of either a constant or linearly decaying cross flow rate. A combination of an exponentially decaying cross flow AF4-UV-MALS-QELS and the utilization of full retention equation was proved to be a useful method for the separation and characterization of egg yolk plasma. Copyright © 2016 Elsevier B.V. All rights reserved.

  4. Surface treatment by the ion flow from electron beam generated plasma in the forevacuum pressure range

    Directory of Open Access Journals (Sweden)

    Klimov Aleksandr

    2018-01-01

    Full Text Available The paper presents research results of peculiarities of gas ion flows usage and their generation from large plasma formation (>50 sq.cm obtained by electron beam ionization of gas in the forevacuum pressure range. An upgraded source was used for electron beam generation, which allowed obtaining ribbon electron beam with no transmitting magnetic field. Absence of magnetic field in the area of ion flow formation enables to obtain directed ion flows without distorting their trajectories. In this case, independent control of current and ion energy is possible. The influence of electron beam parameters on the parameters of beam plasma and ion flow – current energy and density – was determined. The results of alumina ceramics treatment with a beam plasma ions flow are given.

  5. Change of Zonal Flow Spectra in the JIPP T-IIU Tokamak Plasmas

    International Nuclear Information System (INIS)

    Hamada, Y.; Watari, T.; Yamagishi, O.; Nishizawa, A.; Narihara, K.; Kawasumi, Y.; Ido, T.; Kojima, M.; Toi, K.

    2007-01-01

    When Ohmically heated low-density plasmas are additionally heated by higher-harmonics ion-cyclotron-range-of frequency heating, heated by neutral beam injection, or strongly gas puffed, the intensity of zonal flows in the geodesic acoustic mode frequency range in the tokamak core plasma decreases sharply and that of low-frequency zonal flow grows drastically. This is accompanied by a damping of the drift wave propagating in the electron diamagnetic drift direction, turbulence by trapped electron mode (TEM), and the increase of the mode propagating to ion diamagnetic drift direction (ITG). In the half-radius region, TEM and high-frequency zonal flows remain intense in both OH and heated phases. ITG and low-frequency zonal flows grow in heated plasmas, suggesting a strong coupling between ITG and low-frequency zonal flow

  6. Viscosity estimation utilizing flow velocity field measurements in a rotating magnetized plasma

    International Nuclear Information System (INIS)

    Yoshimura, Shinji; Tanaka, Masayoshi Y.

    2008-01-01

    The importance of viscosity in determining plasma flow structures has been widely recognized. In laboratory plasmas, however, viscosity measurements have been seldom performed so far. In this paper we present and discuss an estimation method of effective plasma kinematic viscosity utilizing flow velocity field measurements. Imposing steady and axisymmetric conditions, we derive the expression for radial flow velocity from the azimuthal component of the ion fluid equation. The expression contains kinematic viscosity, vorticity of azimuthal rotation and its derivative, collision frequency, azimuthal flow velocity and ion cyclotron frequency. Therefore all quantities except the viscosity are given provided that the flow field can be measured. We applied this method to a rotating magnetized argon plasma produced by the Hyper-I device. The flow velocity field measurements were carried out using a directional Langmuir probe installed in a tilting motor drive unit. The inward ion flow in radial direction, which is not driven in collisionless inviscid plasmas, was clearly observed. As a result, we found the anomalous viscosity, the value of which is two orders of magnitude larger than the classical one. (author)

  7. Three-dimensional rotational plasma flows near solid surfaces in an axial magnetic field

    Energy Technology Data Exchange (ETDEWEB)

    Gorshunov, N. M., E-mail: gorshunov-nm@nrcki.ru; Potanin, E. P., E-mail: potanin45@yandex.ru [National Research Center Kurchatov Institute (Russian Federation)

    2016-11-15

    A rotational flow of a conducting viscous medium near an extended dielectric disk in a uniform axial magnetic field is analyzed in the magnetohydrodynamic (MHD) approach. An analytical solution to the system of nonlinear differential MHD equations of motion in the boundary layer for the general case of different rotation velocities of the disk and medium is obtained using a modified Slezkin–Targ method. A particular case of a medium rotating near a stationary disk imitating the end surface of a laboratory device is considered. The characteristics of a hydrodynamic flow near the disk surface are calculated within the model of a finite-thickness boundary layer. The influence of the magnetic field on the intensity of the secondary flow is studied. Calculations are performed for a weakly ionized dense plasma flow without allowance for the Hall effect and plasma compressibility. An MHD flow in a rotating cylinder bounded from above by a retarding cap is considered. The results obtained can be used to estimate the influence of the end surfaces on the main azimuthal flow, as well as the intensities of circulating flows in various devices with rotating plasmas, in particular, in plasma centrifuges and laboratory devices designed to study instabilities of rotating plasmas.

  8. Temporary targeted renal blood flow interruption using a reverse thermosensitive polymer to facilitate bloodless partial nephrectomy: a swine survival study.

    Science.gov (United States)

    Harty, Niall J; Laskey, Daniel H; Moinzadeh, Alireza; Flacke, Sebastian; Benn, James A; Villani, Rosanna; Kalra, Aarti; Libertino, John A; Madras, Peter N

    2012-09-01

    What's known on the subject? and What does the study add? Lumagel™ is a reverse thermosensitive polymer (RTP) that has previously been described in the literature as providing temporary vascular occlusion to allow for bloodless partial nephrectomy (PN) while maintaining blood flow to the untargeted portion of the kidney. At body temperature, Lumagel™ has the consistency of a viscous gel but upon cooling rapidly converts to a liquid state and does not reconstitute thereafter. This property has allowed for it to be used in situations requiring temporary vascular occlusion. Previous experience with similar RTPs in coronary arteries proved successful, with no detectable adverse events. We have previously described our technique for temporary vascular occlusion of the main renal artery, as well as segmental and sub-segmental renal branches, to allow for bloodless PN in either an open or minimally invasive approach. These experiments were performed in the acute setting. This study is a two-armed survival trial to assess whether this RTP is as safe as hilar clamping for bloodless PN. Surviving animals showed normal growth after using the RTP, absence of toxicity, no organ dysfunction, and no pathological changes attributable to the RTP. We conclude that Lumagel™ is as safe as conventional PN with hilar clamping, while adding the advantage of uninterrupted perfusion during renal resection. To examine whether randomly selected regions of the kidney could undergo temporary flow interruption with a reverse thermosensitive polymer (RTP), Lumagel™ (Pluromed, Inc., Woburn, MA, USA), followed by partial nephrectomy (PN), without adding risks beyond those encountered in the same procedure with the use of hilar clamping. A two-armed (RTP vs hilar clamp), 6-week swine survival study was performed. Four swine underwent PN using hilar clamps, while six underwent PN with flow interruption using the RTP. The RTP, administered angiographically, was used for intraluminal occlusion

  9. Plasma generated in culture medium induces damages of HeLa cells due to flow phenomena

    Science.gov (United States)

    Sato, Yusuke; Sato, Takehiko; Yoshino, Daisuke

    2018-03-01

    Plasma in a liquid has been anticipated as an effective tool for medical applications, however, few reports have described cellular responses to plasma generated in a liquid similar to biological fluids. Herein we report the effects of plasma generated in a culture medium on HeLa cells. The plasma in the culture medium produced not only heat, shock waves, and reactive chemical species but also a jet flow with sub millimeter-sized bubbles. Cells exposed to the plasma exhibited detachment, morphological changes, and changes in the actin cytoskeletal structure. The experimental results suggest that wall shear stress over 160 Pa was generated on the surface of the cells by the plasma. It is one of the main factors that cause those cellular responses. We believe that our findings would provide valuable insight into advancements in medical applications of plasma in a liquid.

  10. Electric force on plasma ions and the momentum of the ion-neutrals flow

    Science.gov (United States)

    Makrinich, G.; Fruchtman, A.; Zoler, D.; Boxman, R. L.

    2018-05-01

    The electric force on ions in plasma and the momentum flux carried by the mixed ion-neutral flow were measured and found to be equal. The experiment was performed in a direct-current gas discharge of cylindrical geometry with applied radial electric field and axial magnetic field. The unmagnetized plasma ions, neutralized by magnetized electrons, were accelerated radially outward transferring part of the gained momentum to neutrals. Measurements were taken for various argon gas flow rates between 13 and 100 Standard Cubic Centimeter per Minute, for a discharge current of 1.9 A and a magnetic field intensity of 136 G. The plasma density, electron temperature, and plasma potential were measured at various locations along the flow. These measurements were used to determine the local electric force on the ions. The total electric force on the plasma ions was then determined by integrating radially the local electric force. In parallel, the momentum flux of the mixed ion-neutral flow was determined by measuring the force exerted by the flow on a balance force meter (BFM). The maximal plasma density was between 6 × 1010 cm-3 and 5 × 1011 cm-3, the maximal electron temperature was between 8 eV and 25 eV, and the deduced maximal electric field was between 2200 V/m and 5800 V/m. The force exerted by the mixed ion-neutral flow on the BFM agreed with the total electric force on the plasma ions. This agreement showed that it is the electric force on the plasma ions that is the source of the momentum acquired by the mixed ion-neutral flow.

  11. Nitric oxide, prostaglandins and angiotensin II in the regulation of renal medullary blood flow during volume expansion.

    Science.gov (United States)

    Moreno, Carol; Llinás, María T; Rodriguez, Francisca; Moreno, Juan M; Salazar, F Javier

    2016-03-01

    Regulation of medullary blood flow (MBF) is essential in maintaining renal function and blood pressure. However, it is unknown whether outer MBF (OMBF) and papillary blood flow (PBF) are regulated independently when extracellular volume (ECV) is enhanced. The aim of this study was to determine whether OMBF and PBF are differently regulated and whether there is an interaction between nitric oxide (NO), prostaglandins (PGs) and angiotensin II (Ang II) in regulating OMBF and PBF when ECV is enhanced. To achieve these goals, OMBF and PBF were measured by laser-Doppler in volume-expanded rats treated with a cyclooxygenase inhibitor (meclofenamate, 3 mg/kg) and/or a NO synthesis inhibitor (L-nitro-arginine methyl ester (L-NAME), 3 μg/kg/min) and/or Ang II (10 ng/kg/min). OMBF was unchanged by NO or PGs synthesis inhibition but decreased by 36 % (P blood flows to the outer medulla and renal papilla are differently regulated and showing that there is a complex interaction between NO, PGs and Ang II in regulating OMBF and PBF when ECV is enhanced.

  12. Non Equilbrium Vibrational Kinetics in Expanding Plasma Flows

    International Nuclear Information System (INIS)

    Colonna, Gianpiero

    2008-01-01

    The supersonic expansion of a plasma is a system of interest for aerospace applications, ranging from propulsion to hypersonic wind tunnels. Under these conditions the plasma shows significant departures from chemical and thermal equilibrium, similarly to post-discharge conditions. The multitemperature description is not adequate because the internal level distributions show tails overpopulated with respect to a Boltzmann distribution. The state-to-state approach has to be used, including the interaction with free electrons which follow non-maxwellian distributions.

  13. Plasma flow to a surface using the iterative Monte Carlo method

    International Nuclear Information System (INIS)

    Pitcher, C.S.

    1994-01-01

    The iterative Monte Carlo (IMC) method is applied to a number of one-dimensional plasma flow problems, which encompass a wide range of conditions typical of those present in the boundary of magnetic fusion devices. The kinetic IMC method of solving plasma flow to a surface consists of launching and following particles within a grid of 'bins' into which weights are left according to the time a particle spends within a bin. The density and potential distributions within the plasma are iterated until the final solution is arrived at. The IMC results are compared with analytical treatments of these problems and, in general, good agreement is obtained. (author)

  14. Distal renal tubular acidosis

    Science.gov (United States)

    ... this disorder. Alternative Names Renal tubular acidosis - distal; Renal tubular acidosis type I; Type I RTA; RTA - distal; Classical RTA Images Kidney anatomy Kidney - blood and urine flow References Bose A, Monk RD, Bushinsky DA. Kidney ...

  15. Renal blood flow investigations with 133xenon and the anger scintillation camera in the hyperacute xenograft rejection of the rabbit kidney

    International Nuclear Information System (INIS)

    Heidenreich, P.; Oberdorfer, M.; Hoer, G.; Erhardt, W.; Krueger, P.; Pielsticker, K.

    1976-01-01

    The aim of this study was to demonstrate the advantage and validity of 133 Xe-washout externally monitored by the scintillation camera. Until now there were no reports on quantitative blood flow studies in hyperacute rejection of transplanted kidneys using a scintillation camera. Within 35 minutes after e-vivo hemoperfusion of rabbit kidneys by cats we found a simultaneous progressive decrease of renal blood flow, renal cortical blood flow as well as of the intrarenal distribution of renal cortical blood flow in all cases. The hyperacute rejection of xenografts could be verified in every case histologically. Using the scintillation camera we were able to detect regional perfusion defects caused by artifical air embolism as well as by preexisting cortical infarction. (orig.) [de

  16. Modeling Vertical Plasma Flows in Solar Filament Barbs

    Science.gov (United States)

    Litvinenko, Y.

    2003-12-01

    Speeds of observed flows in quiescent solar filaments are typically much less than the local Alfvén speed. This is why the flows in filament barbs can be modeled by perturbing a local magnetostatic solution describing the balance between the Lorentz force, gravity, and gas pressure in a barb. Similarly, large-scale filament flows can be treated as adiabatically slow deformations of a force-free magnetic equilibrium that describes the global structure of a filament. This approach reconciles current theoretical models with the puzzling observational result that some of the flows appear to be neither aligned with the magnetic field nor controlled by gravity.

  17. Helically symmetric equilibria with pressure anisotropy and incompressible plasma flow

    Science.gov (United States)

    Evangelias, A.; Kuiroukidis, A.; Throumoulopoulos, G. N.

    2018-02-01

    We derive a generalized Grad-Shafranov equation governing helically symmetric equilibria with pressure anisotropy and incompressible flow of arbitrary direction. Through the most general linearizing ansatz for the various free surface functions involved therein, we construct equilibrium solutions and study their properties. It turns out that pressure anisotropy can act either paramegnetically or diamagnetically, the parallel flow has a paramagnetic effect, while the non-parallel component of the flow associated with the electric field has a diamagnetic one. Also, pressure anisotropy and flow affect noticeably the helical current density.

  18. Plasma sheet fast flows and auroral dynamics during substorm: a case study

    Directory of Open Access Journals (Sweden)

    N. L. Borodkova

    2002-03-01

    Full Text Available Interball-1 observations of a substorm development in the mid-tail on 16 December 1998 are compared with the auroral dynamics obtained from the Polar UV imager. Using these data, the relationship between plasma flow directions in the tail and the location of the auroral activation is examined. Main attention is given to tailward and earth-ward plasma flows, interpreted as signatures of a Near Earth Neutral Line (NENL. It is unambiguously shown that in the mid-plasma sheet the flows were directed tailward when the auroral bulge developed equatorward of the spacecraft ionospheric footprint. On the contrary, when active auroras moved poleward of the Interball-1 projection, earthward fast flow bursts were observed. This confirms the concept that the NENL (or flow reversal region is the source of auroras forming the poleward edge of the auroral bulge. The observed earthward flow bursts have all typical signatures of Bursty Bulk Flows (BBFs, described by Angelopolous et al. (1992. These BBFs are related to substorm activations starting at the poleward edge of the expanded auroral bulge. We interpret the BBFs as a result of reconnection pulses occurring tail-ward of Interball-1. In addition, some non-typically observed phenomena were detected in the plasma sheet during this substorm: (i tailward/earthward flows were superimposed on a very strong duskward flow, and (ii wavy structures of both magnetic field and plasma density were registered. The latter observation is probably linked to the filamentary structure of the current sheet.Key words. Magnetospheric physics (auroral phenomena; plasma sheet; storms and substorms

  19. Asymmetry reversal of ion collection by mach probes in flowing unmagnetized plasmas

    International Nuclear Information System (INIS)

    Ko, E; Hershkowitz, N

    2006-01-01

    Measurements of ion current in flowing unmagnetized plasmas were performed with planar and spherical Mach probes in two different devices, one a dc multi-dipole plasma device for subsonic flow within a presheath region and the other a double plasma device for supersonic flow. Asymmetry reversal, which is higher ion current to the downstream side of the probe compared with the upstream side current, was observed for high probe bias compared with the electron temperature, relatively low ion drift velocity and Debye length comparable to probe radius. These data are in qualitative agreement with a recent numerical calculation by Hutchinson. As suggested by Hutchinson, it was found that the current ratio depended on the plasma parameters, especially for finite Debye length and high probe bias. Asymmetry reversal emphasizes the lack of validity of using the current ratio except for narrow parameter ranges. This study is the first experiment to demonstrate the non-intuitive phenomenon predicted by Hutchinson's numerical calculation

  20. Effects of plasma current on nonlinear interactions of ITG turbulence, zonal flows and geodesic acoustic modes

    International Nuclear Information System (INIS)

    Angelino, P; Bottino, A; Hatzky, R; Jolliet, S; Sauter, O; Tran, T M; Villard, L

    2006-01-01

    The mutual interactions of ion temperature gradient (ITG) driven modes, zonal flows and geodesic acoustic modes (GAM) in tokamak plasmas are investigated using a global nonlinear gyrokinetic formulation with totally unconstrained evolution of temperature gradient and profile. A series of numerical simulations with the same initial temperature and density profile specifications is performed using a sequence of ideal MHD equilibria differing only in the value of the total plasma current, in particular with identical magnetic shear profiles and shapes of magnetic surfaces. On top of a bursty or quasi-steady state behaviour the zonal flows oscillate at the GAM frequency. The amplitude of these oscillations increases with the value of the safety factor q, resulting in a less effective suppression of ITG turbulence by zonal flows at a lower plasma current. The turbulence-driven volume-averaged radial heat transport is found to scale inversely with the total plasma current

  1. Characteristics of steady-state plasma flow in the tokamak limiter scrape-off layer

    International Nuclear Information System (INIS)

    Petrov, V.G.

    1984-01-01

    Steady state plasma flow in the scrape-off layer of a toroidal limiter is discussed. The force balance along the torus minor radius is taken into account, from which follows that the plasma pressure gradient is balanced by the ponderomotive force (1/c) j-vectorxB-vector, which arises in the presence of a current density component perpendicular to the magnetic field. The limiter has an important effect on the electric current flow in the scrape-off layer. It is shown that the electric potential and plasma density values differ from one side of the limiter to the other; this leads to plasma drift along the minor radius. The characteristic length of change in the plasma density is found to be of the order of the ion cyclotron radius calculated for a poloidal magnetic field. (author)

  2. Simulation of rarefied low pressure RF plasma flow around the sample

    International Nuclear Information System (INIS)

    Zheltukhin, V S; Shemakhin, A Yu

    2017-01-01

    The paper describes a mathematical model of the flow of radio frequency plasma at low pressure. The hybrid mathematical model includes the Boltzmann equation for the neutral component of the RF plasma, the continuity and the thermal equations for the charged component. Initial and boundary conditions for the corresponding equations are described. The electron temperature in the calculations is 1-4 eV, atoms temperature in the plasma clot is (3-4) • 10 3 K, in the plasma jet is (3.2-10) • 10 2 K, the degree of ionization is 10 -7 -10 -5 , electron density is 10 15 -10 19 m -3 . For calculations plasma parameters is developed soft package on C++ program language, that uses the OpenFOAM library package. Simulations for the vacuum chamber in the presence of a sample and the free jet flow were carried out. (paper)

  3. Simulation of rarefied low pressure RF plasma flow around the sample

    Science.gov (United States)

    Zheltukhin, V. S.; Shemakhin, A. Yu

    2017-01-01

    The paper describes a mathematical model of the flow of radio frequency plasma at low pressure. The hybrid mathematical model includes the Boltzmann equation for the neutral component of the RF plasma, the continuity and the thermal equations for the charged component. Initial and boundary conditions for the corresponding equations are described. The electron temperature in the calculations is 1-4 eV, atoms temperature in the plasma clot is (3-4) • 103 K, in the plasma jet is (3.2-10) • 102 K, the degree of ionization is 10-7-10-5, electron density is 1015-1019 m-3. For calculations plasma parameters is developed soft package on C++ program language, that uses the OpenFOAM library package. Simulations for the vacuum chamber in the presence of a sample and the free jet flow were carried out.

  4. Rational surfaces, ExB sheared flows and transport interplay in fusion plasmas

    International Nuclear Information System (INIS)

    Hidalgo, Carlos; Pedrosa, Maria A.; Erents, Kevin

    2001-01-01

    Experimental evidence of a strong interplay between magnetic topology (rational surfaces) and the generation of ExB sheared flows has been observed in the plasma edge region of stellarator (TJ-II) and tokamak (JET) devices. Constant and varying in time ExB sheared flows are close to the critical value to trigger the transition to improved confinement regimes. The plasma conditions where this has been observed are clearly below the power threshold to trigger the formation of transport barriers. Flows driven by fluctuations are candidates to explain these experimental results. (author)

  5. Driving mechanism of SOL plasma flow and effects on the divertor performance in JT-60U

    International Nuclear Information System (INIS)

    Asakura, N.

    2002-01-01

    SOL plasma flow plays an important role in the plasma transport along the field lines, and influences control of the divertor plasma and impurity ions. Recently, mechanisms producing the SOL flow such as drifts produced by electric field and pressure gradient are pointed out. In JT-60U, three reciprocating Mach probes were installed at the high-field-side (HFS) baffle, low-field-side (LFS) midplane and just below the X-point. The measurements of the SOL flow and plasma profiles both at the HFS and LFS, for the first time, found out the SOL flow pattern and its driving mechanism. 'Flow reversal' was found near the separatrix of the HFS and LFS. Radial profiles of the SOL flow were similar to those calculated numerically using the UEDGE code with the plasma drifts included. SOL particle fluxes towards the HFS and LFS divertors were, for the first time, evaluated. Important physics issues for the divertor design and operation, such as in-out asymmetries of the heat and particle fluxes, and control of impurity ions with intense gas puff and divertor pump (puff and pump), were investigated. (author)

  6. Dynamic gas flow during plasma operation in TMX-U

    International Nuclear Information System (INIS)

    Pickles, W.L.; Carter, M.R.; Clower, C.A.; Drake, R.P.; Hunt, A.L.; Simonen, T.C.; Turner, W.C.

    1982-01-01

    Control of the neutral density outside of the plasma radius is essential for proper operation of the various plasma configurations in TMX-U. TMX-U excess-beam, stream-gun, gas-box, and beam-reflux gases are pumped internally in regions defined by 73 0 Ti-gettered liners and warm Ti-gettered plasma liners. The array of fast and slow ion gauges - a large TMX-U diagnostic - has been used to measure the dynamic pressure in many of the liner-defined regions on three time scales. The natural divertor action, or plasma pump effect, of mirror plasmas has been measured using the ion gauge diagnostics on a fast time scale during operation of TMX-U with ECRH start-up. Routine operation of TMX-U is enhanced by the ability to verify the effectiveness of gettering and to locate leaks using pressure data collected on the two slow time scales. A computer code, DYNAVAC 6, which treats TMX-U as a set of conductance-coupled regions with pumping and sources in each region, has been used to successfully model the overall gas dynamics during all phases of TMX-U operation

  7. Plasma flow velocity measurements using a modulated Michelson interferometer

    NARCIS (Netherlands)

    Howard, J.; Meijer, F. G.

    1997-01-01

    This paper discusses the possibility of flow velocity reconstruction using passive spectroscopic techniques. We report some preliminary measurements of the toroidal flow velocity of hydrogen atoms in the RTP tokamak using a phase modulated Michelson interferometer. (C) 1997 Elsevier Science S.A.

  8. Exercise training normalizes renal blood flow responses to acute hypoxia in experimental heart failure: role of the α1-adrenergic receptor.

    Science.gov (United States)

    Pügge, Carolin; Mediratta, Jai; Marcus, Noah J; Schultz, Harold D; Schiller, Alicia M; Zucker, Irving H

    2016-02-01

    Recent data suggest that exercise training (ExT) is beneficial in chronic heart failure (CHF) because it improves autonomic and peripheral vascular function. In this study, we hypothesized that ExT in the CHF state ameliorates the renal vasoconstrictor responses to hypoxia and that this beneficial effect is mediated by changes in α1-adrenergic receptor activation. CHF was induced in rabbits. Renal blood flow (RBF) and renal vascular conductance (RVC) responses to 6 min of 5% isocapnic hypoxia were assessed in the conscious state in sedentary (SED) and ExT rabbits with CHF with and without α1-adrenergic blockade. α1-adrenergic receptor expression in the kidney cortex was also evaluated. A significant decline in baseline RBF and RVC and an exaggerated renal vasoconstriction during acute hypoxia occurred in CHF-SED rabbits compared with the prepaced state (P renal denervation (DnX) blocked the hypoxia-induced renal vasoconstriction in CHF-SED rabbits. α1-adrenergic protein in the renal cortex of animals with CHF was increased in SED animals and normalized after ExT. These data provide evidence that the acute decline in RBF during hypoxia is caused entirely by the renal nerves but is only partially mediated by α1-adrenergic receptors. Nonetheless, α1-adrenergic receptors play an important role in the beneficial effects of ExT in the kidney. Copyright © 2016 the American Physiological Society.

  9. Plasma flow measurement using directional Langmuir probe under weakly ion-magnetized conditions

    Energy Technology Data Exchange (ETDEWEB)

    Nagaoka, Kenichi; Okamoto, Atsushi [Graduate School of Science, Nagoya Univ., Nagoya (Japan); Yoshimura, Shinji; Tanaka, Masayoshi Y. [National Inst. for Fusion Science, Toki, Gifu (Japan)

    2000-07-01

    It is both experimentally and theoretically demonstrated that ion flow velocity at an arbitrary angle with respect to the magnetic field can be measured with a directional Langmuir probe. Based on the symmetry argument, we show that the effect of magnetic field on directional probe current is exactly canceled in determining the ion flow velocity, and obtain the generalized relation between flow velocity and directional probe currents valid for any flowing direction. The absolute value of the flow velocity is determined by an in situ calibration method of the probe. The applicability limit of the present method to a strongly ion-magnetized plasma is experimentally examined. (author)

  10. Production of free radical by magnetized sheet plasma with vertical gas-flow

    International Nuclear Information System (INIS)

    Tonegawa, Akira; Takatori, Masahiko; Kawamura, Kazutaka

    1995-01-01

    Free radicals play an important role in plasma processing, environment problem, and space plasma and so on because of their outstanding physical properties. Although much work has been done on the free radicals in the reactive plasma, very little is known about the production mechanism of the free radicals against various plasma parameters. To overcome this problem, we have proposed to do a new system of a magnetized sheet plasma with vertical gas-flow. The sheet plasma is a special type of strongly magnetized highly ionized slab plasma. This system is controlled to the parameters of radicals and plasma independently. Therefore, it is possible to make a quantitative analysis of free radicals as the simple one. In this paper, we describe the magnetized sheet plasma with vertical gas-flow system and report the preliminary results of production of the free radical. In particular, we show to produce and control the OH free radical which has been the most commonly studied combustion species

  11. Active Control of Flow around NACA 0015 Airfoil by Using DBD Plasma Actuator

    Directory of Open Access Journals (Sweden)

    Şanlısoy A.

    2013-04-01

    Full Text Available In this study, effect of plasma actuator on a flat plate and manipulation of flow separation on NACA0015 airfoil with plasma actuator at low Reynolds numbers were experimentally investigated. In the first section of the study, plasma actuator which consists of positive and grounded electrode couple and dielectric layer, located on a flat plate was actuated at different frequencies and peak to peak voltages in range of 3-5 kHz and 6-12 kV respectively. Theinduced air flow velocity on the surface of flat plate was measured by pitot tube at different locations behind the actuator. The influence of dielectricthickness and unsteady actuation with duty cycle was also examined. In the second section, the effect of plasma actuator on NACA0015 airfoil was studied atReynolds number 15000 and 30000. Four plasma actuators were placed at x/C = 0.1, 0.3, 0.5 and 0.9, and different electrode combinations were activated by sinusoidal signal. Flow visualizations were done when the attack angles were 0°, 5°, 10°, 15° and 20°. The results indicate that up to the 15° attack angle, the separated flow was reattached by plasma actuator at 12kV peak to peak voltage and 4 kHz frequency. However, 12 kVpp voltage was insufficient to reattach the flow at 20° angle of attack. The separated flow could be reattached by increasing the voltage up to 13 kV. Lift coefficient was also increased by the manipulated flow over the airfoil. Results showed that even high attack angles, the actuators can control the flow separation and prevent the airfoil from stall at low Reynolds numbers.

  12. Observations of plasma vortices in the vicinity of flow-braking: a case study

    Directory of Open Access Journals (Sweden)

    K. Keika

    2009-08-01

    Full Text Available We examine fast plasma flows and magnetic field fluctuations observed by THEMIS at 03:00–03:30 UT on 12 December 2007. All THEMIS probes are situated in the near-Earth plasma sheet (XSM>−10 RE with 1–2 RE spacecraft separations in azimuthal and radial directions. We focus on the observations of plasma convective flows made simultaneously by more than one THEMIS probe. At about 03:10 UT and 03:14 UT, the THEMIS P2 probe observed earthward flows of >100 km/s. The THEMIS P1 probe, located duskward and earthward of P2, observed tailward flows under a positive Bz. The inner most probe THEMIS P4, located at almost the same MLT as THEMIS P1 and P2, did not see any clear flow. We examine the convective flow patterns for the THEMIS observations. We conclude that plasma vortices are formed near the region where the earthward flows slow down and turn in azimuthal directions.

  13. Triple-probe method applied to the direct display of plasma parameters in a supersonic flowing continuum plasma

    International Nuclear Information System (INIS)

    Ogram, G.L.; Chang, J.; Hobson, R.M.

    1979-01-01

    The calibration of electrostatic triple-probe voltage and current response in a supersonic continuum plasma has been carried out using a low-pressure shock tube. The electron temperature T/sub e/ and charge number density N/sub e/ are compared to probe voltage and current response, respectively, for a useful range of plasma parameters (1 13 13 is the nondimensional probe voltage). The dependence of probe response on Debye ratio R/sub p//lambda/sub D/ and various flow parameters was investigated. The probe voltage response was found to depend significantly on the Debye ratio. Expressions for electron temperature determination by triple probe are presented

  14. Identification and Characterization of Plasma Cells in Normal Human Bone Marrow by High-Resolution Flow Cytometry

    NARCIS (Netherlands)

    Terstappen, Leonardus Wendelinus Mathias Marie; Johnsen, Steen; Segers-Nolten, Gezina M.J.; Loken, Michael R.

    1990-01-01

    The low frequency of plasma cells and the lack of specific cell surface markers has been a major obstacle for a detailed characterization of plasma cells in normal human bone marrow. Multiparameter flow cytometry enabled the identification of plasma cells in normal bone marrow aspirates. The plasma

  15. Aortic coarctation diagnosed by renal Doppler flow patterns in a hypertensive young patient: a case report

    International Nuclear Information System (INIS)

    Sari, S.; Kara, K.; Verim, S.

    2012-01-01

    Full text: Introduction: Aortic coarctation is a congenital malformation, which can cause systemic hypertension and subsequent complications, and causes of secondary hypertension, affecting in differential pressures in the upper and lower extremities. Because hypertension is caused by aortic coarctation, tends to be resistant to medical therapy, early recognition and surgical rectification are important. Objectives and tasks: In this article, we aimed to point out that renal Doppler sonography is a beneficial and frequently used to evaluate secondary hypertension, if there are bilateral tardus-parvus wave patterns are detected. Thus, bilateral renal artery stenosis, aortic stenosis, and coarctation should be considered in this condition. Materials and methods: A 23-year-old male who has six-month history of hypertension. He was referred by a cardiologist for investigation of his secondary hypertension. There was an ascending aortic dilatation, left ventricular hypertrophy in his echocardiography. Results: The patient's blood pressure was measured as 160/90 mm Hg in his both arms. Renal Doppler sonography was performed to identify the potential cause of secondary hypertension, specifically renal artery stenosis, after tardus-parvus pulse waves were noted in both renal intralobar-arteries. Aortic coarctation is suspected and then a chest computed tomography (CT) was performed to evaluate supra-diaphragmatic vessel abnormalities. The CT exposed a stenotic lesion in the isthmus of the aorta. The patient was transferred to cardiovascular surgery department for treatment. Conclusion: Careful physical examination should be performed in all hypertensive patients. If bilateral tardus-parvus wave pattern are seen in patients who has been referred for Doppler evaluation on suspicion of renovascular hypertension, aortic coarctation should be considered as differential diagnosis

  16. Effects of high-fat diet and losartan on renal cortical blood flow using contrast ultrasound imaging.

    Science.gov (United States)

    Declèves, Anne-Emilie; Rychak, Joshua J; Smith, Dan J; Sharma, Kumar

    2013-11-01

    Obesity-related kidney disease occurs as a result of complex interactions between metabolic and hemodynamic effects. Changes in microvascular perfusion may play a major role in kidney disease; however, these changes are difficult to assess in vivo. Here, we used perfusion ultrasound imaging to evaluate cortical blood flow in a mouse model of high-fat diet-induced kidney disease. C57BL/6J mice were randomized to a standard diet (STD) or a high-fat diet (HFD) for 30 wk and then treated either with losartan or a placebo for an additional 6 wk. Noninvasive ultrasound perfusion imaging of the kidney was performed during infusion of a microbubble contrast agent. Blood flow within the microvasculature of the renal cortex and medulla was derived from imaging data. An increase in the time required to achieve full cortical perfusion was observed for HFD mice relative to STD. This was reversed following treatment with losartan. These data were concurrent with an increased glomerular filtration rate in HFD mice compared with STD- or HFD-losartan-treated mice. Losartan treatment also abrogated fibro-inflammatory disease, assessed by markers at the protein and messenger level. Finally, a reduction in capillary density was found in HFD mice, and this was reversed upon losartan treatment. This suggests that alterations in vascular density may be responsible for the elevated perfusion time observed by imaging. These data demonstrate that ultrasound contrast imaging is a robust and sensitive method for evaluating changes in renal microvascular perfusion and that cortical perfusion time may be a useful parameter for evaluating obesity-related renal disease.

  17. Saline-induced natriuresis and renal blood flow in conscious dogs: effects of sodium infusion rate and concentration

    DEFF Research Database (Denmark)

    Sandgaard, N C F; Andersen, J L; Holstein-Rathlou, N-H

    2005-01-01

    AIM: This study focused on static and dynamic changes in total renal blood flow (RBF) during volume expansion and tested whether a change in RBF characteristics is a necessary effector mechanism in saline-induced natriuresis. METHODS: The aortic flow subtraction technique was used to measure RBF...... continuously. Identical amounts of NaCl (2.4 mmol kg(-1)) were given as slow isotonic (Iso, 120 min), slow hypertonic (Hyper, 120 min), and rapid isotonic loads (IsoRapid, 30 min). RESULTS: During Iso and IsoRapid, arterial blood pressure increased slightly (6-7 mmHg), and during Hyper it remained unchanged...... saline loading simulating daily sodium intake, the rate of sodium excretion may increase 10-20-fold without any change in mean arterial blood pressure or in RBF. Regulatory responses to changes in total body NaCl levels appears, therefore, to be mediated primarily by neurohumoral mechanisms and may occur...

  18. The Efficiency of Quartz Particles Evaporation in the Argon Plasma Flow of the RF Inductively Coupled Plasma Torch

    Directory of Open Access Journals (Sweden)

    Yu. M. Grishin

    2017-01-01

    Full Text Available Owing to high-power density and high-purity plasma, a RF inductively coupled plasma torch (ICPT is widely used both in research laboratory and in industry. The potential RF ICPT application areas are powders spheroidisation, waste treatment, thermal spraying, etc.In the last decade the investigation was focused on the treatment processes of quartz into polycrystalline silicon. An analysis of these results has shown that the increasing productivity and producing high-purity silicon can be achieved only when using the electrodeless radio-frequency induction plasma torches and in case the optimum conditions for evaporation of SiO2solid particles are realized.Optimization of the RF ICPT design and power parameters calls for a wide range of computational studies. In spite of the fact that to date a large number of efforts to calculate the evaporation efficiency of powder materials have been made, a number of issues, as applied to the problem of obtaining silicon, require further research.In this paper, we present the results of a two-dimensional numerical simulation of the heating and evaporation of quartz particles in the RF ICPT channel with axial flow of gases. The main aim is to determine how the axial position of the central tube (through which the particles are injected into the discharge zone, the dispersion of the quartz powder, the amplitude of the discharge current (and, respectively, flow regimes impact on the evaporation efficiency of quartz particles.The paper presented the numerical modeling results of heating and evaporation processes of quartz particles supplied by transporting gas to the RF ICPT channel with axial gas flow (argon. Defined the impact of the axial position of the central tube, the plasma flow regime, the discharge current, the flow rate of transporting gas, and other parameters on the evaporation efficiency of quartz particles.It is shown that the evaporation efficiency of particles reaches its maximum when their

  19. Comparison of ASL and DCE MRI for the non-invasive measurement of renal blood flow: quantification and reproducibility

    Energy Technology Data Exchange (ETDEWEB)

    Cutajar, Marica; Hales, Patrick W.; Clark, Christopher A.; Gordon, Isky [UCL Institute of Child Health, Imaging and Biophysics Unit, London (United Kingdom); Thomas, David L. [UCL Institute of Neurology, Department of Brain Repair and Rehabilitation, London (United Kingdom); Banks, T. [Great Ormond Street Hospital, Department of Radiology, London (United Kingdom)

    2014-06-15

    To investigate the reproducibility of arterial spin labelling (ASL) and dynamic contrast-enhanced (DCE) magnetic resonance imaging (MRI) and quantitatively compare these techniques for the measurement of renal blood flow (RBF). Sixteen healthy volunteers were examined on two different occasions. ASL was performed using a multi-TI FAIR labelling scheme with a segmented 3D-GRASE imaging module. DCE MRI was performed using a 3D-FLASH pulse sequence. A Bland-Altman analysis was used to assess repeatability of each technique, and determine the degree of correspondence between the two methods. The overall mean cortical renal blood flow (RBF) of the ASL group was 263 ± 41 ml min{sup -1} [100 ml tissue]{sup -1}, and using DCE MRI was 287 ± 70 ml min{sup -1} [100 ml tissue]{sup -1}. The group coefficient of variation (CV{sub g}) was 18 % for ASL and 28 % for DCE-MRI. Repeatability studies showed that ASL was more reproducible than DCE with CV{sub g}s of 16 % and 25 % for ASL and DCE respectively. Bland-Altman analysis comparing the two techniques showed a good agreement. The repeated measures analysis shows that the ASL technique has better reproducibility than DCE-MRI. Difference analysis shows no significant difference between the RBF values of the two techniques. (orig.)

  20. Gas flow dependence for plasma-needle disinfection of S. mutans bacteria

    Energy Technology Data Exchange (ETDEWEB)

    Goree, J [Department of Physics and Astronomy, University of Iowa, Iowa City, IA 52242 (United States); Liu Bin [Department of Physics and Astronomy, University of Iowa, Iowa City, IA 52242 (United States); Drake, David [Dows Institute for Dental Research, Dept. of Endodontics, College of Dentistry, University of Iowa, Iowa City, IA 52242 (United States)

    2006-08-21

    The role of gas flow and transport mechanisms are studied for a small low-power impinging jet of weakly-ionized helium at atmospheric pressure. This plasma needle produces a non-thermal glow discharge plasma that kills bacteria. A culture of Streptococcus mutans (S. mutans) was plated onto the surface of agar, and spots on this surface were then treated with plasma. Afterwards, the sample was incubated and then imaged. These images, which serve as a biological diagnostic for characterizing the plasma, show a distinctive spatial pattern for killing that depends on the gas flow rate. As the flow is increased, the killing pattern varies from a solid circle to a ring. Images of the glow reveal that the spatial distribution of energetic electrons corresponds to the observed killing pattern. This suggests that a bactericidal species is generated in the gas phase by energetic electrons less than a millimetre from the sample surface. Mixing of air into the helium plasma is required to generate the observed O and OH radicals in the flowing plasma. Hydrodynamic processes involved in this mixing are buoyancy, diffusion and turbulence.

  1. Gas flow dependence for plasma-needle disinfection of S. mutans bacteria

    International Nuclear Information System (INIS)

    Goree, J; Liu Bin; Drake, David

    2006-01-01

    The role of gas flow and transport mechanisms are studied for a small low-power impinging jet of weakly-ionized helium at atmospheric pressure. This plasma needle produces a non-thermal glow discharge plasma that kills bacteria. A culture of Streptococcus mutans (S. mutans) was plated onto the surface of agar, and spots on this surface were then treated with plasma. Afterwards, the sample was incubated and then imaged. These images, which serve as a biological diagnostic for characterizing the plasma, show a distinctive spatial pattern for killing that depends on the gas flow rate. As the flow is increased, the killing pattern varies from a solid circle to a ring. Images of the glow reveal that the spatial distribution of energetic electrons corresponds to the observed killing pattern. This suggests that a bactericidal species is generated in the gas phase by energetic electrons less than a millimetre from the sample surface. Mixing of air into the helium plasma is required to generate the observed O and OH radicals in the flowing plasma. Hydrodynamic processes involved in this mixing are buoyancy, diffusion and turbulence

  2. Interaction of a vacuum arc plasma beam with an obstacle positioned normal to the plasma flow

    International Nuclear Information System (INIS)

    Zarchin, O; Zhitomirsky, V N; Goldsmith, S; Boxman, R L

    2003-01-01

    The effect of an obstacle positioned normal to a plasma jet produced by a vacuum arc plasma source on the radial distribution of ion flux in the vicinity of the obstacle was studied. This study was motivated by interest in the mutual influence of tightly packed substrates on coatings in industrial vacuum arc deposition systems. The experimental system consisted of a vacuum arc plasma source, a straight plasma duct, and a multi-probe consisting of a removable disc obstacle and a set of ring probes for measuring the radial ion flux. A dc arc discharge was ignited in vacuum between a truncated cone-shaped Cu cathode and an annular anode. The plasma jet produced by cathode spots passed through the anode aperture into the straight plasma duct. An axial magnetic field guided the plasma jet in the duct. The multi-probe consisted of a removable disc obstacle and a set of five ring probes for measuring the radial plasma flux as a function of distance from the disc obstacle. The rings and the disc probes were coaxially arranged on the multi-probe assembly and positioned so that plasma from the source passed through the ring probes and then encountered the disc. The influence of the obstacle was determined by measuring the ring ion currents, both in the presence of the obstacle, and when the disc obstacle was removed. The difference between the measured ion currents with and without the obstacle was interpreted to be the contribution of reflected or sputtered particles from the obstacle to the radial ion flux. The ring probes were biased by -60 V with respect to the grounded anode, to collect the saturated ion current. The multi-probe was connected to a movable stem, and positioned at different distances from the plasma source. A plasma density of ∼6 x 10 17 m -3 was estimated in this study based on the ion current to the obstacle. The radial ion flux collected by the ring probes increased by 20-25% due to the presence of the obstacle. As the calculated mean free path for

  3. Plasma Control of Turbine Secondary Flows, Phase I

    Data.gov (United States)

    National Aeronautics and Space Administration — We propose Phase I and II efforts that will focus on turbomachinery flow control. Specifically, the present work will investigate active control in a high speed...

  4. Tissue expression and plasma levels of adrenomedullin in renal cancer patients

    DEFF Research Database (Denmark)

    Michelsen, Jens; Thiesson, Helle; Walter, Steen

    2006-01-01

    that AM is increased in CC-RCC tumours and that AM is a plasma biomarker for CC-RCC. Tumours and non-malignant kidney tissue were obtained from patients that underwent unilateral nephrectomy. Blood samples were drawn at the day of surgery, 3-6 days after surgery and 4-5 weeks after surgery. AM m...... conclude that elevated tissue AM is a distinguishing feature of CC-RCC compared with other kidney tumours. Plasma AM is not suited as a tumour marker for this disease....

  5. Self-separation of blood plasma from whole blood during the capillary flow in microchannel

    Science.gov (United States)

    Nunna, Bharath Babu; Zhuang, Shiqiang; Lee, Eon Soo

    2017-11-01

    Self-separation of blood plasma from whole blood in microchannels is of great importance due to the enormous range of applications in healthcare and diagnostics. Blood is a multiphase complex fluid, composed of cells suspended in blood plasma. RBCs are the suspended particles whose shape changes during the flow of blood. The primary constituents of blood are erythrocytes or red blood cells (RBCs), leukocytes or white blood cells (WBCs), thrombocytes or platelets and blood plasma. The existence of RBCs in blood makes the blood a non-Newtonian fluid. The current study of separation of blood plasma from whole blood during self-driven flows in a single microchannel without bifurcation, by enhancing the capillary effects. The change in the capillary effect results in a change in contact angle which directly influences the capillary flow. The flow velocity directly influences the net force acting on the RBCs and influence the separation process. The experiments are performed on the PDMS microchannels with different contact angles by altering the surface characteristics using plasma treatment. The change in the separation length is studied during the capillary flow of blood in microchannel. Bharath Babu Nunna is a researcher in mechanical engineering and implementing the novel and innovative technologies in the biomedical devices to enhance the sensitivity of the disease diagnosis.

  6. Finite toroidal flow generated by unstable tearing mode in a toroidal plasma

    Energy Technology Data Exchange (ETDEWEB)

    Hao, G. Z., E-mail: haogz@swip.ac.cn; Wang, A. K.; Xu, Y. H.; He, H. D.; Xu, M.; Qu, H. P.; Peng, X. D.; Xu, J. Q.; Qiu, X. M. [Southwestern Institute of Physics, P.O. Box 432, Chengdu 610041 (China); Liu, Y. Q. [Culham Centre for Fusion Energy, Culham Science Centre, Abingdon OX14 3DB (United Kingdom); Sun, Y. [Institute of Plasma Physics, Chinese Academic of Sciences, P.O. Box 1126, Hefei 230031 (China); Cui, S. Y. [School of Mathematics and Statistics Science, Ludong University, Yantai 264025 (China)

    2014-12-15

    The neoclassical toroidal plasma viscosity torque and electromagnetic torque, generated by tearing mode (TM) in a toroidal plasma, are numerically investigated using the MARS-Q code [Liu et al., Phys. Plasmas 20, 042503 (2013)]. It is found that an initially unstable tearing mode can intrinsically drive a toroidal plasma flow resulting in a steady state solution, in the absence of the external momentum input and external magnetic field perturbation. The saturated flow is in the order of 0.5%ω{sub A} at the q=2 rational surface in the considered case, with q and ω{sub A} being the safety factor and the Alfven frequency at the magnetic axis, respectively. The generation of the toroidal flow is robust, being insensitive to the given amplitude of the perturbation at initial state. On the other hand, the flow amplitude increases with increasing the plasma resistivity. Furthermore, the initially unstable tearing mode is fully stabilized by non-linear interaction with the self-generated toroidal flow.

  7. Propagation of atmospheric pressure helium plasma jet into ambient air at laminar gas flow

    International Nuclear Information System (INIS)

    Pinchuk, M; Kurakina, N; Spodobin, V; Stepanova, O

    2017-01-01

    The formation of an atmospheric pressure plasma jet (APPJ) in a gas flow passing through the discharge gap depends on both gas-dynamic properties and electrophysical parameters of the plasma jet generator. The paper presents the results of experimental and numerical study of the propagation of the APPJ in a laminar flow of helium. A dielectric-barrier discharge (DBD) generated inside a quartz tube equipped with a coaxial electrode system, which provided gas passing through it, served as a plasma source. The transition of the laminar regime of gas flow into turbulent one was controlled by the photography of a formed plasma jet. The corresponding gas outlet velocity and Reynolds numbers were revealed experimentally and were used to simulate gas dynamics with OpenFOAM software. The data of the numerical simulation suggest that the length of plasma jet at the unvarying electrophysical parameters of DBD strongly depends on the mole fraction of ambient air in a helium flow, which is established along the direction of gas flow. (paper)

  8. Propagation of atmospheric pressure helium plasma jet into ambient air at laminar gas flow

    Science.gov (United States)

    Pinchuk, M.; Stepanova, O.; Kurakina, N.; Spodobin, V.

    2017-05-01

    The formation of an atmospheric pressure plasma jet (APPJ) in a gas flow passing through the discharge gap depends on both gas-dynamic properties and electrophysical parameters of the plasma jet generator. The paper presents the results of experimental and numerical study of the propagation of the APPJ in a laminar flow of helium. A dielectric-barrier discharge (DBD) generated inside a quartz tube equipped with a coaxial electrode system, which provided gas passing through it, served as a plasma source. The transition of the laminar regime of gas flow into turbulent one was controlled by the photography of a formed plasma jet. The corresponding gas outlet velocity and Reynolds numbers were revealed experimentally and were used to simulate gas dynamics with OpenFOAM software. The data of the numerical simulation suggest that the length of plasma jet at the unvarying electrophysical parameters of DBD strongly depends on the mole fraction of ambient air in a helium flow, which is established along the direction of gas flow.

  9. Characteristics of pulsed plasma synthetic jet and its control effect on supersonic flow

    Directory of Open Access Journals (Sweden)

    Di Jin

    2015-02-01

    Full Text Available The plasma synthetic jet is a novel flow control approach which is currently being studied. In this paper its characteristic and control effect on supersonic flow is investigated both experimentally and numerically. In the experiment, the formation of plasma synthetic jet and its propagation velocity in quiescent air are recorded and calculated with time resolved schlieren method. The jet velocity is up to 100 m/s and no remarkable difference has been found after changing discharge parameters. When applied in Mach 2 supersonic flow, an obvious shockwave can be observed. In the modeling of electrical heating, the arc domain is not defined as an initial condition with fixed temperature or pressure, but a source term with time-varying input power density, which is expected to better describe the influence of heating process. Velocity variation with different heating efficiencies is presented and discussed and a peak velocity of 850 m/s is achieved in still air with heating power density of 5.0 × 1012 W/m3. For more details on the interaction between plasma synthetic jet and supersonic flow, the plasma synthetic jet induced shockwave and the disturbances in the boundary layer are numerically researched. All the results have demonstrated the control authority of plasma synthetic jet onto supersonic flow.

  10. Turbulence spectra, transport, and E × B flows in helical plasmas

    International Nuclear Information System (INIS)

    Watanabe, T.-H.; Nunami, M.; Sugama, H.; Satake, S.; Matsuoka, S.; Ishizawa, A.; Tanaka, K.; Maeyama, Shinya

    2012-11-01

    Gyrokinetic simulation of ion temperature gradient turbulence and zonal flows for helical plasmas has been validated against the Large Helical Device experiments with high ion temperature, where a reduced modeling of ion heat transport is also considered. It is confirmed by the entropy transfer analysis that the turbulence spectrum elongated in the radial wavenumber space is associated with successive interactions with zonal flows. A novel multi-scale simulation for turbulence and zonal flows in poloidally-rotating helical plasmas has demonstrated strong zonal flow generation by turbulence, which implies that turbulent transport processes in non-axisymmetric systems are coupled to neoclassical transport through the macroscopic E × B flows determined by the ambipolarty condition for neoclassical particle fluxes. (author)

  11. Successful Desensitization of T cell Flow Cytometry Crossmatch Positive Renal Transplant Recipients Using Plasmapheresis and Super High-Dose Intravenous Immunoglobulin

    Directory of Open Access Journals (Sweden)

    Yoichi Kakuta, MD, PhD

    2018-01-01

    Full Text Available Background. High-dose IVIG (2 g/kg alone or low-dose IVIG (100 mg/kg in conjunction with plasma exchange is typically administered as a renal transplantation desensitization therapy. Herein, we monitored changes in T cell and B cell flow cytometry crossmatch (FCXM to assess the effects of short-term super high-dose IVIG (4 g/kg administration with plasmapheresis before living-donor renal transplantation. Methods. Seventeen patients, each showing positive T cell FCXM (median ratio, ≥ 1.4 after 2 rounds of double-filtration plasmapheresis, received 4-day regimens of IVIG (1 g/kg per day over 1-week periods. T cell and B cell FCXM determinations were obtained after every IVIG dose and again up to 4 weeks after initiating IVIG to ascertain negative conversion of T cell FCXM (median ratio < 1.4. The primary study endpoint was the percentage of patients achieving T cell FCXM-negative status after the 4-dose IVIG regimen. Results. Upon completion (4 g/kg total or discontinuation of IVIG administration, 8 (47.1% of 17 patients displayed negative T cell FCXM. Based on Kaplan-Meier estimates, the cumulative T cell FCXM-negative conversion rate 4 weeks after IVIG administration initiation was 60.3%. The T cell FCXM-negative conversion rates after cumulative doses of 1, 2, 3, and 4 g/kg IVIG were 29.4%, 35.3%, 56.3%, and 46.7%, respectively. Conclusions. Desensitization of donor-specific antibody-positive renal transplant recipients seems achievable in only a subset of recipients through IVIG dosing (1 g/kg × 4 within 1 week after double-filtration plasmapheresis. The T cell FCXM-negative conversion rate resulting from a cumulative IVIG dose of 3 g/kg or greater surpassed that attained via conventional single-dose IVIG (2 g/kg protocol. This short-term high-dose IVIG desensitization protocol may be an alternative to conventional protocols for recipients with donor-specific antibody.

  12. Atmospheric pulsed laser deposition of plasmonic nanoparticle films of silver with flowing gas and flowing atmospheric plasma

    Science.gov (United States)

    Khan, T. M.; Pokle, A.; Lunney, J. G.

    2018-04-01

    Two methods of atmospheric pulsed laser deposition of plasmonic nanoparticle films of silver are described. In both methods the ablation plume, produced by a 248 nm, 20 ns excimer laser in gas, is strongly confined near the target and forms a nanoparticle aerosol. For both the flowing gas, and the atmospheric plasma from a dielectric barrier discharge plasma source, the aerosol is entrained in the flow and carried to a substrate for deposition. The nanoparticle films produced by both methods were examined by electron microscopy and optical absorption spectroscopy. With plasma assistance, the deposition rate was significantly enhanced and the film morphology altered. With argon gas, isolated nanoparticles of 20 nm size were obtained, whereas in argon plasma, the nanoparticles are aggregated in clusters of 90 nm size. Helium gas also leads to the deposition of isolated nanoparticles, but with helium plasma, two populations of nanoparticles are observed: one of rounded particles with a mean size of 26 nm and the other of faceted particles with a mean size 165 nm.

  13. Characteristics of a plasma flow field produced by a metal array bridge foil explosion

    Science.gov (United States)

    Junying, WU; Long, WANG; Yase, LI; Lijun, YANG; Manzoor, SULTAN; Lang, CHEN

    2018-07-01

    To improve the energy utilization efficiency of metal bridge foil explosion, and increase the function range of plasmas, array bridge foil explosion experiments with different structures were performed. A Schlieren photographic measurement system with a double-pulse laser source was used to observe the flow field of a bridge foil explosion. The evolution laws of plasmas and shock waves generated by array bridge foil explosions of different structures were analyzed and compared. A multi-phase flow calculation model was established to simulate the electrical exploding process of a metal bridge foil. The plasma equation of state was determined by considering the effect of the changing number of particles and Coulomb interaction on the pressure and internal energy. The ionization degree of the plasma was calculated via the Saha–Eggert equation assuming conditions of local thermal equilibrium. The exploding process of array bridge foils was simulated, and the superposition processes of plasma beams were analyzed. The variation and distribution laws of the density, temperature, pressure, and other important parameters were obtained. The results show that the array bridge foil has a larger plasma jet diameter than the single bridge foil for an equal total area of the bridge foil. We also found that the temperature, pressure, and density of the plasma jet’s center region sharply increase because of the superposition of plasma beams.

  14. Inhibition of plasma kallikrein-kinin system to alleviate renal injury and arthritis symptoms in rats with adjuvant-induced arthritis.

    Science.gov (United States)

    Zhu, Jie; Wang, Hui; Chen, Jingyu; Wei, Wei

    2018-04-01

    Rheumatoid arthritis (RA) is a chronic systemic autoimmune disease. Impairment of kidney functions in RA was observed. However, the mechanism of kidney injury of RA has not been clear. Plasma kallikrein-kinin system (KKS) was involved in inflammatory processes in kidney disease. This study aimed to explore the role of plasma KKS in immune reactions and kidney injury of RA. The paw of AA rats appeared to be swelling and redness, the arthritis index was significantly increased on the 18, 21 and 24 d after injection and secondary inflammation in multi-sites was observed. Kidney dysfunction accompanied with inflammatory cell infiltration, tubular epithelial cell mitochondrial swelling and vacuolar degeneration, renal glomerular foot process fusions and glomerular basement membrane thickening were observed in AA rats. The expressions of neutrophil gelatinase-associated lipocalin (NGAL) and kidney injury molecule-1 (Kim-1) in kidney of AA rats were increased. In addition, expressions of BK, PK, B1R and B2R in the renal tissue of AA rats were up-regulated. Pro-inflammatory cytokines IL-2, IFN-γ and TNF-α were increased and anti-inflammatory cytokines IL-4 and IL-10 were low in kidney. Plasma kallikrein (PK) inhibitor PKSI-527 attenuated arthritis signs and renal damage, and inhibited BK, PK, B1R and B2R expressions. The protein expressions of P38, p-P38 and p-JNK and IFN-γ and TNF-α were inhibited by PKSI-527. These findings demonstrate that plasma KKS activation contributed to the renal injury of AA rats through MAPK signaling pathway. Plasma KKS might be a potential target for RA therapy.

  15. Cluster observation of plasma flow reversal in the magnetotail during a substorm

    Directory of Open Access Journals (Sweden)

    A. T. Y. Lui

    2006-08-01

    Full Text Available We investigate in detail a reversal of plasma flow from tailward to earthward detected by Cluster at the downstream distance of ~19 RE in the midnight sector of the magnetotail on 22 August 2001. This flow reversal was accompanied by a sign reversal of the Bz component and occurred during the late substorm expansion phase as revealed by simultaneous global view of auroral activity from IMAGE. We examine the associated Hall current system signature, current density, electric field, Lorentz force, and current dissipation/dynamo term, the last two parameters being new features that have not been studied previously for plasma flow reversals. It is found that (1 there was no clear quadrupole Hall current system signature organized by the flow reversal time, (2 the x-component of the Lorentz force did not change sign while the other two did, (3 the timing sequence of flow reversal from the Cluster configuration did not match tailward motion of a single plasma flow source, (4 the electric field was occasionally dawnward, producing a dynamo effect, and (5 the electric field was occasionally larger at the high-latitude plasma sheet than near the neutral sheet. These observations are consistent with the current disruption model for substorms in which these disturbances are due to shifting dominance of multiple current disruption sites and turbulence at the observing location.

  16. Cluster observation of plasma flow reversal in the magnetotail during a substorm

    Directory of Open Access Journals (Sweden)

    A. T. Y. Lui

    2006-08-01

    Full Text Available We investigate in detail a reversal of plasma flow from tailward to earthward detected by Cluster at the downstream distance of ~19 RE in the midnight sector of the magnetotail on 22 August 2001. This flow reversal was accompanied by a sign reversal of the Bz component and occurred during the late substorm expansion phase as revealed by simultaneous global view of auroral activity from IMAGE. We examine the associated Hall current system signature, current density, electric field, Lorentz force, and current dissipation/dynamo term, the last two parameters being new features that have not been studied previously for plasma flow reversals. It is found that (1 there was no clear quadrupole Hall current system signature organized by the flow reversal time, (2 the x-component of the Lorentz force did not change sign while the other two did, (3 the timing sequence of flow reversal from the Cluster configuration did not match tailward motion of a single plasma flow source, (4 the electric field was occasionally dawnward, producing a dynamo effect, and (5 the electric field was occasionally larger at the high-latitude plasma sheet than near the neutral sheet. These observations are consistent with the current disruption model for substorms in which these disturbances are due to shifting dominance of multiple current disruption sites and turbulence at the observing location.

  17. Numerical study on the two-dimensional flows of plasma and ionizing gas using trial particles

    International Nuclear Information System (INIS)

    Brushlinskij, K.V.; Kozlov, A.N.; Morozov, A.I.

    1985-01-01

    Two-dimensional flows of plasma and ionized αs in a channel between two coaxial electrodes are considered in the MHD-model with account of Hall effect. Stationary solutions of the problem on the flow are obtained either analytically in approximation of a ''smooth'' channel - for ideal conducting plasma, or numerically using the methos of establishment - in the ge-neral case of finite conductivity. A method of further numerical analysis of some peculiarities of flow is suggested in the paper. It is based on studying dynamics of single ''test'' particles in fields of the main MHD plasma flow. Trajectory of the test ion is calculated with account for interaction forces with earlier determined electromagentic field and friction responsible for Coulomb collisions with particles of the background flow. The calculations display trajectories of test particles with different masses, initial positions and initial rates. They are shown to be dose to current lines of background medium in plasma of finite conductivity, that testified to the virtue of effectiveness of the MHD-model. In case of ideal conductivity trajectories of test and background particles can noticeably differ from one another. Stabilization effects of motion of particles accidentally knocked out from the flow and separation of pariticles of different mass by electromao.netic forces are considered

  18. Plasma NT-proBNP mirrors the deleterious cardiovascular and renal continuum in hypertension.

    Science.gov (United States)

    Courand, Pierre-Yves; Harbaoui, Brahim; Bècle, Clément; Mouly-Bertin, Carine; Lantelme, Pierre

    2017-03-01

    Background The aims of this study were (a) to test the ability of N-terminal pro-brain natriuretic peptide (NT-proBNP) to detect subclinical target organ damage (TOD) denoted by left ventricular hypertrophy (LVH), aortic stiffness or renal damage and (b) to test its reproducibility in two different conditions in an ancillary study. Methods The study included 837 patients (50.9% men) with hypertension aged 50 ± 24 years with a median 24-h ambulatory blood pressure (BP) of 148/90 mmHg. LVH was assessed by transthoracic echocardiography and echocardiography, aortic stiffness was assessed by carotid-femoral pulse wave (PWV) measurements and renal dysfunction by measurements of the estimated glomerular filtration rate (eGFR) and microalbuminuria. Results After the exclusion of patients with a history of heart failure, NT-proBNP was independently correlated with sex, systolic BP, primary hypertension, PWV, LVH and eGFR, but not with microalbuminuria. The median (interquartile range) NT-proBNP increased gradually according to the number of target organs damaged: 42 (24-70), 77 (39-151), 141 (81-250) and 334 (177-556) pg/mL, for damage to 0, 1, 2 and 3 target organs, respectively ( p secondary hypertension. A threshold at 90 pg/mL for men and 142 pg/mL in women had a specificity of 95% to detect at least one TOD (areas under ROC curve 0.790 and 0.783, respectively). The reproducibility of NT-proBNP was fairly good in this setting ( r = 0.952, p hypertension.

  19. Haemoadsorption reduces the inflammatory response and improves blood flow during ex vivo renal perfusion in an experimental model.

    Science.gov (United States)

    Hosgood, Sarah A; Moore, Tom; Kleverlaan, Theresa; Adams, Tom; Nicholson, Michael L

    2017-10-25

    Ex-vivo normothermic perfusion strategies are a promising new instrument in organ transplantation. The perfusion conditions are designed to be protective however the artificial environment can induce a local inflammatory response. The aim of this study was to determine the effect of incorporating a Cytosorb adsorber into an isolated kidney perfusion system. Porcine kidneys were subjected to 22 h of cold ischaemia then reperfused for 6 h on an ex vivo reperfusion circuit. Pairs of kidneys were randomised to either control (n = 5) or reperfusion with a Cytosorb adsorber (n = 5) integrated into the circuit. Tissue, blood and urine samples were taken for the measurement of inflammation and renal function. Baseline levels of cytokines (IL-6, TNFα, IL-8, IL-10, IL-1β, IL-1α) were similar between groups. Levels of IL-6 and IL-8 in the perfusate significantly increased during reperfusion in the control group but not in the Cytosorb group (P = 0.023, 0.049). Levels of the other cytokines were numerically lower in the Cytosorb group; however, this did not reach statistical significance. The mean renal blood flow (RBF) was significantly higher in the Cytosorb group (162 ± 53 vs. 120 ± 35 mL/min/100 g; P = 0.022). Perfusate levels of prostaglandin E2 were significantly lower in the Cytosorb group (642 ± 762 vs. 3258 ± 980 pg/mL; P = 0.0001). Levels of prostacyclin were significantly lower in the Cytosorb group at 1, 3 and 6 h of reperfusion (P = 0.008, 0.003, 0.0002). Levels of thromboxane were also significantly lower in the Cytosorb group throughout reperfusion (P = 0.005). Haemoadsorption had no effect on creatinine clearance (P = 0.109). Haemoadsorption can reduce the inflammatory response and improve renal blood flow during perfusion. Nonetheless, in this model haemoadsorption had no influence on renal function and this may relate to the broad-spectrum action of the Cytosorb adsorber that also removes potentially important anti

  20. The renal blood flow reserve in healthy humans and patients with atherosclerotic renovascular disease measured by positron emission tomography using [15O]H2O.

    Science.gov (United States)

    Päivärinta, Johanna; Koivuviita, Niina; Oikonen, Vesa; Iida, Hidehiro; Liukko, Kaisa; Manner, Ilkka; Löyttyniemi, Eliisa; Nuutila, Pirjo; Metsärinne, Kaj

    2018-06-11

    Microvascular function plays an important role in ARVD (atherosclerotic renovascular disease). RFR (renal flow reserve), the capacity of renal vasculature to dilate, is known to reflect renal microvascular function. In this pilot study, we assessed PET (positron emission tomography)-based RFR values of healthy persons and renal artery stenosis patients. Seventeen patients with ARVD and eight healthy subjects were included in the study. Intravenous enalapril 1 mg was used as a vasodilatant, and the maximum response (blood pressure and RFR) to it was measured at 40 min. Renal perfusion was measured by means of oxygen-15-labeled water PET. RFR was calculated as a difference of stress flow and basal flow and was expressed as percent [(stress blood flow - basal blood flow)/basal blood flow] × 100%. RFR of the healthy was 22%. RFR of the stenosed kidneys of bilateral stenosis patients (27%) was higher than that of the stenosed kidneys of unilateral stenosis patients (15%). RFR of the contralateral kidneys of unilateral stenosis patients was 21%. There was no difference of statistical significance between RFR values of ARVD subgroups or between ARVD subgroups and the healthy. In the stenosed kidneys of unilateral ARVD patients, stenosis grade of the renal artery correlated negatively with basal (p = 0.04) and stress flow (p = 0.02). Dispersion of RFR values was high. This study is the first to report [ 15 O]H 2 O PET-based RFR values of healthy subjects and ARVD patients in humans. The difference between RFR values of ARVD patients and the healthy did not reach statistical significance perhaps because of high dispersion of RFR values. [ 15 O]H 2 O PET is a valuable non-invasive and quantitative method to evaluate renal blood flow though high dispersion makes imaging challenging. Larger studies are needed to get more information about [ 15 O]H 2 O PET method in evaluation of renal blood flow.

  1. Supersonic flow with shock waves. Monte-Carlo calculations for low density plasma. I

    International Nuclear Information System (INIS)

    Almenara, E.; Hidalgo, M.; Saviron, J. M.

    1980-01-01

    This Report gives preliminary information about a Monte Carlo procedure to simulate supersonic flow past a body of a low density plasma in the transition regime. A computer program has been written for a UNIVAC 1108 machine to account for a plasma composed by neutral molecules and positive and negative ions. Different and rather general body geometries can be analyzed. Special attention is played to tho detached shock waves growth In front of the body. (Author) 30 refs

  2. Global characteristics of zonal flows generated by ion temperature gradient driven turbulence in tokamak plasmas

    International Nuclear Information System (INIS)

    Miyato, Naoaki; Kishimoto, Yasuaki; Li, Jiquan

    2004-08-01

    Global structure of zonal flows driven by ion temperature gradient driven turbulence in tokamak plasmas is investigated using a global electromagnetic Landau fluid code. Characteristics of the coupled system of the zonal flows and the turbulence change with the safety factor q. In a low q region stationary zonal flows are excited and suppress the turbulence effectively. Coupling between zonal flows and poloidally asymmetric pressure perturbations via a geodesic curvature makes the zonal flows oscillatory in a high q region. Also we identify energy transfer from the zonal flows to the turbulence via the poloidally asymmetric pressure perturbations in the high q region. Therefore in the high q region the zonal flows cannot quench the turbulent transport completely. (author)

  3. Numerical analysis of the effect of plasma flow control on enhancing the aerodynamic characteristics of stratospheric screw propeller

    International Nuclear Information System (INIS)

    Cheng Yufeng; Nie Wansheng

    2012-01-01

    Based on the body force aerodynamic actuation mechanism of dielectric barrier discharge (DBD) plasma, the effect of plasma flow control on enhancing the aerodynamic characteristics of ten blade elements equably along the stratospheric screw propeller blade was numerical studied. Then the effect of plasma flow control enhancing the aerodynamic characteristics of stratospheric screw propeller was compared that by the blade element theory method. The results show that the flow separate phenomena will easily happen in the root region and top end region of screw propeller, and the blade elements in the root region of screw propeller may work on the negative attack angle condition. DBD plasma flow control can entirely restrain the faintish flow separate phenomena in middle region of screw propeller. Although DBD plasma flow control can not entirely restrain the badly flow separate phenomena in top end region of screw propeller, it also can enhance the aerodynamic characteristics of blade elements in these regions in same degree. But effect of DBD plasma flow control on enhancing the aerodynamic characteristics of the blade elements working on the negative attack angle condition is ineffectively. It can be concluded that DBD plasma flow control can enhance the aerodynamic characteristics of stratospheric screw propeller, the thrust of the whole propeller and the propeller efficiency in the case of plasma on will increases by a factor of 28.27% and 12.3% respectively compared with that in the case of plasma off studied. (authors)

  4. Plasma equilibria and stationary flows in axisymmetric systems. Pt. 2

    International Nuclear Information System (INIS)

    Zelazny, R.; Stankiewicz, R.; Potempski, S.

    1988-05-01

    Part I of this report described the computational problems connected with the bifurcating solutions to static and extended Grad-Shafranov-Schlueter equations (with stationary flows). Part II is a listing of the computer program for solving the extended Grad-Shafranov-Schlueter equations developed in Part I. (author)

  5. A low plasma 1,25(OH)2 vitamin D/PTH (1-84) ratio predicts worsening of renal function in patients with chronic heart failure.

    Science.gov (United States)

    Masson, Serge; Barlera, Simona; Colotta, Francesco; Magnoli, Michela; Bonelli, Fabrizio; Moro, Milena; Marchioli, Roberto; Tavazzi, Luigi; Tognoni, Gianni; Latini, Roberto

    2016-12-01

    Dysregulation of the vitamin D system promotes renal dysfunction and has direct detrimental effects on the heart. Progressive deterioration of renal function is common in patients with chronic heart failure (HF) and is invariably associated with unfavorable outcomes which can be improved by early identification and timely interventions. We examined the relation between two plasma markers of vitamin D metabolism and worsening of renal function (WRF) in a large cohort of patients with chronic HF. Plasma levels of 1,25-dihydroxyvitamin D (1,25(OH) 2 D) and parathyroid hormone PTH (1-84) were measured in 1237 patients with clinical evidence of chronic and stable HF enrolled in the multicentre GISSI-HF trial and followed for 3.9years. We examined the relation of 1,25(OH) 2 D, PTH(1-84), and their ratio with WRF, defined as first increase in serum creatinine concentration ≥0.3mg/dL and ≥25% at two consecutive measurements at any time during the study. Lower 1,25(OH) 2 D/PTH(1-84) ratio was associated with a higher baseline serum concentration of creatinine, winter season, female sex and older age; 335 patients (29.6%) experienced an episode of WRF. After adjustment, a lower 1,25(OH) 2 D/PTH(1-84) ratio remained significantly associated with a higher risk of WRF (HR=0.75 [0.62-0.90], p=0.002) and correctly reclassified events. This ratio also independently predicted mortality and admission to hospital for cardiovascular reasons. The plasma 1,25(OH) 2 D/PTH(1-84) ratio is a promising indicator of future risk of deterioration of renal function in patients with chronic HF and mild renal impairment, that may serve to optimize therapies and improve outcomes. Copyright © 2016 Elsevier Ireland Ltd. All rights reserved.

  6. Cross-field flow and electric potential in a plasma slab

    Directory of Open Access Journals (Sweden)

    J. De Keyser

    2013-08-01

    Full Text Available We consider cross-field plasma flow inside a field-aligned plasma slab embedded in a uniform background in a 1-dimensional geometry. This situation may arise, for instance, when long-lasting reconnection pulses inject plasma into the inner magnetosphere. The present paper presents a detailed analysis of the structure of the interfaces that separate the slab from the background plasma on either side; a fully kinetic model is used to do so. Since the velocity shear across both interfaces has opposite signs, and given the typical gyroradius differences between injected and background ions and electrons, the structure of both interfaces can be very different. The behaviour of the slab and its interfaces depends critically on the flow of the plasma transverse to the magnetic field; in particular, it is shown that there are bounds to the flow speed that can be supported by the magnetised plasma. Further complicating the picture is the effect of the potential difference between the slab and its environment.

  7. Method of measuring directed electron velocities in flowing plasma using the incoherent regions of laser scattering

    International Nuclear Information System (INIS)

    Jacoby, B.A.; York, T.M.

    1979-02-01

    With the presumption that a shifted Maxwellian velocity distribution adequately describes the electrons in a flowing plasma, the details of a method to measure their directed velocity are described. The system consists of a ruby laser source and two detectors set 180 0 from each other and both set at 90 0 with respect to the incident laser beam. The lowest velocity that can be determined by this method depends on the electron thermal velocity. The application of this diagnostic to the measurement of flow velocities in plasma being lost from the ends of theta-pinch devices is described

  8. On the link between ExB sheared flows and rational surfaces in fusion plasmas

    International Nuclear Information System (INIS)

    Hidalgo, C.; Erents, K.; Matthews, G.

    2000-11-01

    Experimental evidence of flattening in plasma profiles has been observed in the edge region of the JET tokamak. This observation has been interpreted in terms of the influence of rational surfaces on plasma profiles. In the framework of this interpretation, significant ExB sheared flows linked to rational surfaces have been identified. These ExB sheared flows are close to the critical value to trigger the transition to improved confinement regimes. These results can explain the link between the magnetic topology and the generation of transport barriers reported in fusion devices. (author)

  9. DHEA-induced modulation of renal gluconeogenesis, insulin sensitivity and plasma lipid profile in the control- and dexamethasone-treated rabbits. Metabolic studies.

    Science.gov (United States)

    Kiersztan, Anna; Nagalski, Andrzej; Nalepa, Paweł; Tempes, Aleksandra; Trojan, Nina; Usarek, Michał; Jagielski, Adam K

    2016-02-01

    In view of antidiabetic and antiglucocorticoid effects of dehydroepiandrosterone (DHEA) both in vitro and in vivo studies were undertaken: (i) to elucidate the mechanism of action of both dexamethasone phosphate (dexP) and DHEA on glucose synthesis in primary cultured rabbit kidney-cortex tubules and (ii) to investigate the influence of DHEA on glucose synthesis, insulin sensitivity and plasma lipid profile in the control- and dexP-treated rabbits. Data show, that in cultured kidney-cortex tubules dexP significantly stimulated gluconeogenesis by increasing flux through fructose-1,6-bisphosphatase (FBPase). DexP-induced effects were dependent only upon glucocorticoid receptor. DHEA decreased glucose synthesis via inhibition of glucose-6-phosphatase (G6Pase) and suppressed the dexP-induced stimulation of renal gluconeogenesis. Studies with the use of inhibitors of DHEA metabolism in cultured renal tubules showed for the first time that DHEA directly affects renal gluconeogenesis. However, in view of analysis of glucocorticoids and DHEA metabolites levels in urine, it seems likely, that testosterone may also contribute to DHEA-evoked effects. In dexP-treated rabbits, plasma glucose level was not altered despite increased renal and hepatic FBPase and G6Pase activities, while a significant elevation of both plasma insulin and HOMA-IR was accompanied by a decline of ISI index. It thus appears that increased insulin levels were required to maintain normoglycaemia and to compensate the insulin resistance. DHEA alone affected neither plasma glucose nor lipid levels, while it increased insulin sensitivity and diminished both renal and hepatic G6Pase activities. Surprisingly, DHEA co-administrated with dexP did not alter insulin sensitivity, while it partially suppressed the dexP-induced elevation of renal G6Pase activity and plasma cholesterol and triglyceride contents. As (i) gluconeogenic pathway in rabbit is similar to that in human, and (ii) DHEA counteracts several

  10. Optical Measurements in Non-Equilibrium Plasmas and Flows

    Science.gov (United States)

    2009-09-01

    of the polarizability , , of the medium and the time-varying incident electric field ,E(t). p(t) E(t)  (14) Figure 2 Single...162 14 - 7 The polarizability is customarily expanded with respect to the vibrational normal coordinates (or “normal modes”), Q, of the molecule...spectrum, obtained from an argon glow discharge plasma at 50 mbar [36], is shown on the right side of Fig. 7. The inferred temperature is 479 ± 13 K

  11. Progress towards experimental realization of extreme-velocity flow-dominated magnetized plasmas

    Science.gov (United States)

    Weber, T. E.; Adams, C. S.; Welch, D. R.; Kagan, G.; Bean, I. A.; Henderson, B. R.; Klim, A. J.

    2017-10-01

    Interactions of flow-dominated plasmas with other plasmas, neutral gases, magnetic fields, solids etc., take place with sufficient velocity that kinetic energy dominates the dynamics of the interaction (as opposed to magnetic or thermal energy, which dominates in most laboratory plasma experiments). Building upon progress made by the Magnetized Shock Experiment (MSX) at LANL, we are developing the experimental and modeling capability to increase our ultimate attainable plasma velocities well in excess of 1000 km/s. Ongoing work includes designing new pulsed power switches, triggering, and inductive adder topologies; development of novel high-speed optical diagnostics; and exploration of new numerical techniques to specifically model the unique physics of translating/stagnating flow-dominated plasmas. Furthering our understanding of the physical mechanisms of energy conversion from kinetic to other forms, such as thermal energy, non-thermal tails/accelerated populations, enhanced magnetic fields, and radiation (both continuum and line), has wide-ranging significance in basic plasma science, astrophysics, and plasma technology applications such as inertial confinement fusion and intense radiation sources. This work is supported by the U.S. Department of Energy, National Nuclear Security Administration. LA-UR-17-25786.

  12. Depression, 5HTTLPR and BDNF Val66Met polymorphisms, and plasma BDNF levels in hemodialysis patients with chronic renal failure

    Directory of Open Access Journals (Sweden)

    Wang LJ

    2014-07-01

    Full Text Available Liang-Jen Wang,1,* Chih-Ken Chen,2,3,* Heng-Jung Hsu,3,4 I-Wen Wu,3,4 Chiao-Yin Sun,3,4 Chin-Chan Lee3,41Department of Child and Adolescent Psychiatry, Kaohsiung Chang Gung Memorial Hospital and Chang Gung University College of Medicine, Kaohsiung, Taiwan; 2Department of Psychiatry, Chang Gung Memorial Hospital, Keelung, Taiwan; 3Chang Gung University School of Medicine, Taoyuan, Taiwan; 4Department of Nephrology, Chang Gung Memorial Hospital, Keelung, Taiwan *LJW and CKC are joint first authors and contributed equally to this manuscriptObjective: Depression is the most prevalent comorbid psychiatric disease among hemodialysis patients with end-stage renal disease. This cross-sectional study investigated whether depression in hemodialysis patients is associated with the polymorphism of the 5' flanking transcriptional region (5-HTTLPR of the serotonin transporter gene, the valine (Val-to-methionine (Met substitution at codon 66 (Val66Met polymorphism of the brain-derived neurotrophic factor (BDNF gene, or plasma BDNF levels.Methods: A total of 188 participants (mean age: 58.5±14.0 years; 89 men and 99 women receiving hemodialysis at the Chang Gung Memorial Hospital were recruited. The diagnosis of major depressive disorder (MDD was confirmed using the Chinese version of the Mini International Neuropsychiatric Interview. The genotypes of 5-HTTLPR and BDNF Val66Met were conducted using polymerase chain reactions plus restriction fragment length polymorphism analysis. The plasma BDNF levels were measured using an enzyme-linked immunosorbent assay kit.Results: Forty-five (23.9% patients fulfilled the Diagnostic and Statistical Manual of Mental Disorders, Fourth Edition (DSM-IV-TR criteria for a MDD. There were no significant effects of the 5-HTTLPR or BDNF Val66Met gene polymorphism on MDD among the hemodialysis patients. The plasma BDNF levels correlated significantly with age (P=0.003 and sex (P=0.047 but not with depression, the genotypes of 5

  13. Cerebral and Renal Oxygen Saturation Are Not Compromised in the Presence of Retrograde Blood Flow in either the Ascending or Descending Aorta in Term or Near-Term Infants with Left-Sided Obstructive Lesions

    NARCIS (Netherlands)

    van der Laan, Michelle E.; Mebius, Mirthe J.; Roofthooft, Marcus T. R.; Bos, Arend F.; Berger, Rolf M. F.; Kooi, Elisabeth M. W.

    2017-01-01

    Background: In infants with left-sided obstructive lesions (LSOL), the presence of retrograde blood flow in either the ascending or descending aorta may lead to diminished cerebral and renal blood flow, respectively. Objectives: Our aim was to compare cerebral and renal tissue oxygen saturation

  14. Flowing Plasma Interaction with an Electric Sail Tether Element

    Science.gov (United States)

    Schneider, Todd; Vaughn, Jason; Wright, Kenneth; Anderson, Allen; Stone, Nobie

    2017-01-01

    Harnessing the power of the solar wind, an Electric Sail, or E-sail, is a relatively new concept that promises to deliver high speed propellant-less propulsion. The electric sail is an invention made in 2006 at the Kumpula Space Centre in Finland by Pekka Janhunen [Janhunen and Sandroos, 2007]. At its core, an electric sail utilizes multiple positively biased tethers which exchange momentum with solar wind protons via the repelling electric field established around each tether, in other words, by reflecting the solar wind protons. Recognizing the solar wind is a plasma, the effective repelling area of each tether is increased significantly by the formation a plasma sheath around each tether. Fig. 1 shows schematically a spacecraft employing an electric sail. The positive voltage bias (greater than10kV) applied to each tether naturally results in electron collection. Therefore, the electric sail concept necessarily includes an electron source (electron gun) to return collected electrons to space and maintain the positive bias of the tether system.

  15. MHD equilibrium of toroidal fusion plasma with stationary flows; Rownowaga MHD toroidalnej plazmy termojadrowej z przeplywami

    Energy Technology Data Exchange (ETDEWEB)

    Galkowski, A. [Institute of Atomic Energy, Otwock-Swierk (Poland)

    1994-12-31

    Non-linear ideal MHD equilibria in axisymmetric system with flows are examined, both in 1st and 2nd ellipticity regions. Evidence of the bifurcation of solutions is provided and numerical solutions of several problems in a tokamak geometry are given, exhibiting bifurcation phenomena. Relaxation of plasma in the presence of zero-order flows is studied in a realistic toroidal geometry. The field aligned flow allows equilibria with finite pressure gradient but with homogeneous temperature distribution. Numerical calculations have been performed for the 1st and 2nd ellipticity regimes of the extended Grad-Shafranov-Schlueter equation. Numerical technique, alternative to the well-known Grad`s ADM methods has been proposed to deal with slow adiabatic evolution of toroidal plasma with flows. The equilibrium problem with prescribed adiabatic constraints may be solved by simultaneous calculations of flux surface geometry and original profile functions. (author). 178 refs, 37 figs, 5 tabs.

  16. Shear flow instability in a partially-ionized plasma sheath around a fast-moving vehicle

    International Nuclear Information System (INIS)

    Sotnikov, V. I.; Mudaliar, S.; Genoni, T. C.; Rose, D. V.; Oliver, B. V.; Mehlhorn, T. A.

    2011-01-01

    The stability of ion acoustic waves in a sheared-flow, partially-ionized compressible plasma sheath around a fast-moving vehicle in the upper atmosphere, is described and evaluated for different flow profiles. In a compressible plasma with shear flow, instability occurs for any velocity profile, not just for profiles with an inflection point. A second-order differential equation for the electrostatic potential of excited ion acoustic waves in the presence of electron and ion collisions with neutrals is derived and solved numerically using a shooting method with boundary conditions appropriate for a finite thickness sheath in contact with the vehicle. We consider three different velocity flow profiles and find that in all cases that neutral collisions can completely suppress the instability.

  17. Two-Phase Flow Regimes and Discharge Characteristics of a Plasma Electrohydrodynamic Atomization

    International Nuclear Information System (INIS)

    Sun Ming; Borocilo, D.; Harvel, G. D.; Chang, J. S.; Ibe, M.; Matsubara, H.; Hirata, H.; Fanson, P.

    2011-01-01

    Experimental investigation was conducted to study the flow regimes and discharge characteristics of plasma electrohydrodynamic atomization (EHDA) for decane (C 10 H 22 ) under pulsed applied negative voltage. The experimental parameters were set as the flow rate of decane from 0 mL/min to 10 mL/min and the DC charging voltage from DC 0 V to 12 V with a pulse repetition rates of 200 Hz. The flow regime of decane was observed and the volume-to-electrical charge ratio was measured. Unlike a conventional EHDA system, the results show that a corona discharge was initiated at the edge of the hollow electrode at a specific corona on-set voltage of -17 kV or -20 kV in the case with or without decane flow, respectively. This phenomenon was defined as plasma EHDA.

  18. Parallel ion flow velocity measurement using laser induced fluorescence method in an electron cyclotron resonance plasma

    International Nuclear Information System (INIS)

    Yoshimura, Shinji; Okamoto, Atsushi; Terasaka, Kenichiro; Ogiwara, Kohei; Tanaka, Masayoshi Y.; Aramaki, Mitsutoshi

    2010-01-01

    Parallel ion flow velocity along a magnetic field has been measured using a laser induced fluorescence (LIF) method in an electron cyclotron resonance (ECR) argon plasma with a weakly-diverging magnetic field. To measure parallel flow velocity in a cylindrical plasma using the LIF method, the laser beam should be injected along device axis; however, the reflection of the incident beam causes interference between the LIF emission of the incident and reflected beams. Here we present a method of quasi-parallel laser injection at a small angle, which utilizes the reflected beam as well as the incident beam to obtain the parallel ion flow velocity. Using this method, we observed an increase in parallel ion flow velocity along the magnetic field. The acceleration mechanism is briefly discussed on the basis of the ion fluid model. (author)

  19. Impairment of skin blood flow during post-occlusive reactive hyperhemy assessed by laser Doppler flowmetry correlates with renal resistive index.

    Science.gov (United States)

    Coulon, P; Constans, J; Gosse, P

    2012-01-01

    We lack non-invasive tools for evaluating the coronary and renal microcirculations. Since cutaneous Doppler laser exploration has evidenced impaired cutaneous microvascular responses in coronary artery disease and in impaired renal function, we wanted to find out if there was a link between the impairments in the cutaneous and renal microcirculations. To specify the significance of the rise in the renal resistive index (RI), which is still unclear, we also sought relations between RI and arterial stiffness. We conducted a cross-sectional controlled study in a heterogeneous population including hypertensive patients of various ages with or without a history of cardiovascular disease along with a healthy control group. The cutaneous microcirculation was evaluated by laser Doppler flowmetry of the post-occlusive reactive hyperhemy (PORH) and of the hyperhemy to heat. The renal microcirculation was evaluated by measurement of the RI. Arterial stiffness was evaluated from an ambulatory measurement of the corrected QKD(100-60) interval. We included 22 hypertensives and 11 controls of mean age 60.6 vs 40.8 years. In this population, there was a correlation between RI and basal zero to peak flow variation (BZ-PF) (r=-0.42; P=0.02) and a correlation between RI and rest flow to peak flow variation (RF-PF) (r=-0.44; P=0.01). There was also a significant correlation between RI and the corrected QKD(100-60) (r=-0.47; P=0.01). The significant correlation between PORH parameters and RI indicates that the functional modifications of the renal and cutaneous microcirculations tend to evolve in parallel during ageing or hypertension. The relation between RI and arterial stiffness shows that RI is a compound index of both renal microvascular impairment and the deterioration of macrovascular mechanics.

  20. Comparison of glomerular filtration rate measured by plasma sample technique, Cockroft Gault method and Gates’ method in voluntary kidney donors and renal transplant recipients

    International Nuclear Information System (INIS)

    Hephzibah, Julie; Shanthly, Nylla; Oommen, Regi

    2013-01-01

    There are numerous methods for calculation of glomerular filtration rate (GFR), which is a crucial measurement to identify patients with renal disease. The aim of this study is to compare four different methods of GFR calculation. Clinical setup, prospective study. Data was collected from routine renal scans done for voluntary kidney donors (VKD) or renal transplant recipients 6 months after transplantation. Following technetium-99m diethylene triamine penta acetic acid injection, venous blood samples were collected from contralateral arm at 120, 180, and 240 min through an indwelling venous cannula and direct collection by syringe. A total volume of 1 ml of plasma from each sample and standards were counted in an automatic gamma counter for 1 min. Blood samples taken at 120 min and 240 min were used for double plasma sample method (DPSM) and a sample taken at 180 min for single plasma sample method (SPSM). Russell's formulae for SPSM and DPSM were used for GFR estimation. Gates’ method GFR was calculated by vendor provided software. Correlation analysis was performed using Pearson's correlation test. SPSM correlated well with DPSM. GFR value in healthy potential kidney donors has a significant role in the selection of donors. The mean GFR ± (standard deviation) in VKD using SPSM, DPSM, camera depth method and Cockroft Gault method was 134.6 (25.9), 137.5 (42.4), 98.6 (15.9), 83.5 (21.1) respectively. Gates’ GFR calculation did not correlate well with plasma sampling method. Calculation of GFR plays a vital role in the management of renal patients, hence it was noted that Gates GFR may not be a reliable method of calculation. SPSM was more reliable. DPSM is reliable but cumbersome. It is difficult to accurately calculate GFR without a gold standard

  1. Three Flow Features behind the Flow Control Authority of DBD Plasma Actuator: Result of High-Fidelity Simulations and the Related Experiments

    Directory of Open Access Journals (Sweden)

    Kozo Fujii

    2018-04-01

    Full Text Available Both computational and experimental studies are conducted for understanding of the flow separation control mechanism of a DBD (dielectric barrier discharge plasma actuator. Low speed flows over an airfoil are considered. A DBD plasma actuator is attached near the leading edge of an airfoil and the mechanism of flow control of this small device is discussed. The DBD plasma actuator, especially in burst mode, is shown to be very effective for controlling flow separation at Reynolds number of 6.3 × 104, when applied to the flows at an angle of attack higher than the stall. The analysis reveals that the flow structure includes three remarkable features that provide good authority for flow separation control with the appropriate actuator parameters. With proper setting of the actuator parameters to enhance the effective flow features for the application, good flow control can be achieved. Based on the analysis, guidelines for the effective use of DBD plasma actuators are proposed. A DBD plasma actuator is also applied to the flows under cruise conditions. With the DBD plasma actuator attached, a simple airfoil turns out to show higher lift-to-drag ratio than a well-designed airfoil.

  2. Parameters of the plasma of a dc pulsating discharge in a supersonic air flow

    Energy Technology Data Exchange (ETDEWEB)

    Shibkov, V. M., E-mail: shibkov@phys.msu.ru; Shibkova, L. V.; Logunov, A. A. [Moscow State University, Faculty of Physics (Russian Federation)

    2017-03-15

    A dc discharge in a cold (T = 200 K) supersonic air flow at a static pressure of 200–400 Torr was studied experimentally. The excited unsteady pulsating discharge has the form of a thin plasma channel with a diameter of ≤1 mm, stretched downstream the flow. Depending on the discharge current, the pulsation frequency varies from 800 to 1600 Hz and the electron temperature varies from 8000 to 15000 K.

  3. Plasma flow during the brightening of proton aurora in the cusp

    DEFF Research Database (Denmark)

    Taguchi, S.; Hosokawa, K.; Suzuki, S.

    2010-01-01

    On the basis of simultaneous observations from the Super Dual Auroral Radar Network (SuperDARN), the far ultraviolet instrument on the IMAGE spacecraft, and a magnetometer installed on the east coast of Greenland, we present the characteristics of plasma flow during a westward moving proton auror...... to the traveling bulge at the polar cap boundary, which is the footprint of a flux transfer event, and imply that the preexisting vortical flow may be intensified when it becomes inflow to the bulge....

  4. Transport barriers with and without shear flows in a magnetized plasma

    International Nuclear Information System (INIS)

    Martinell, Julio J.

    2014-01-01

    Different ways of producing a transport barrier in a toroidal magnetized plasma are discussed and the properties of the barriers are analyzed. The first mechanism is associated with the presence of a sheared plasma flow that is present in a limited region of the plasma, which creates a zonal flow. In contrast to the usual paradigm stating that the sheared flow reduces the turbulence correlation length and leads to suppression of the fluctuation driven transport in the region of highest shear, it is shown that from the perspective of chaotic transport of plasma particles in the fluctuation fields, the transport barrier is formed in the region of zero shear and it can be destroyed when the fluctuation level is high enough. It is also shown that finite gyroradius effects modify the dynamics and introduces new conditions for barrier formation. The second mechanism considers a method in which radio-frequency waves injected into the plasma can stabilize the drift waves and therefore the anomalous transport is reduced, creating a barrier. This process does not involve the presence of sheared flows and depends only on the effect of the RF wave field on the drift waves. The stabilizing effect in this case is due to the nonlinear ponderomotive force which acts in a way that offsets the pressure gradient destabilization. Finally, a mechanism based on the ponderomotive force of RF waves is described which produces poloidal plasma rotation around the resonant surface due to the asymmetry of induced transport; it creates a transport barrier by shear flow stabilization of turbulence

  5. PAH clearance after renal ischemia and reperfusion is a function of impaired expression of basolateral Oat1 and Oat3

    OpenAIRE

    Bischoff, Ariane; Bucher, Michael; Gekle, Michael; Sauvant, Christoph

    2014-01-01

    Abstract Determination of renal plasma flow (RPF) by para‐aminohippurate (PAH) clearance leads to gross underestimation of this respective parameter due to impaired renal extraction of PAH after renal ischemia and reperfusion injury. However, no mechanistic explanation for this phenomenon is available. Based on our own previous studies we hypothesized that this may be due to impairment of expression of the basolateral rate limiting organic anion transporters Oat1 and Oat3. Thus, we investigat...

  6. Driving mechanism of SOL plasma flow and effects on the divertor performance in JT-60U

    International Nuclear Information System (INIS)

    Asakura, N.; Takenaga, H.; Sakurai, S.

    2003-01-01

    The measurements of the SOL flow and plasma profiles both at the high-field-side (HFS) and low field- side (LFS), for the first time, identified the SOL flow pattern and its driving mechanism. 'Flow reversal' was found near the HFS and LFS separatrix of the main plasma for the ion ∇β drift direction towards the divertor. Radial profiles of the SOL flow were similar to those calculated numerically using the UEDGE code with the plasma drifts included although Mach numbers in measurements were greater than those obtained numerically. Particle fluxes towards the HFS and LFS divertors produced by the parallel SOL flow and E r xB drift flow were evaluated. The particle flux for the case of intense gas puff and divertor pump (puff and pump) was investigated, and it was found that both the Mach number and collisionality were enhanced, in particular, at HFS. Drift flux in the private flux region was also evaluated, and important physics issues for the divertor design and operation, such as in-out asymmetries of the heat and particle fluxes, and control of impurity ions were investigated. (author)

  7. Driving mechanism of SOL plasma flow an effects on the divertor performance in JT-60U

    International Nuclear Information System (INIS)

    Asakura, Nobuyuki; Takenaga, H.; Sakurai, S.

    2003-01-01

    The measurements of the scrape-off layer(SOL) flow and plasma profiles both at the high-field-side (HFS) and low-field-side (LFS), for the first time, identified the SOL flow pattern and its driving mechanism. 'Flow reversal' was found near the HFS and LFS separatrix of the main plasma for the ion ∇B drift direction towards the divertor, Radial profiles of the SOL flow were similar to those calculated numerically using the UEDGE code with the plasma drifts included although Mach numbers in measurements were greater than those obtained numerically. Particle fluxes towards the HFS and LFS divertors produced by the parallel SOL flow and E r xB drift flow were evaluated. The particle flux for the case of intense gas puff and divertor pump (puff and pump) was investigated, and it was found that both the Mach number and collisionality were enhanced, in particular, at HFS. Drift flux in the private flux region was also evaluated, and important physics issues for the divertor design and operation, such as in-out asymmetries of the heat and particle fluxes, and control of impurity ions were investigated. (author)

  8. High Mach flow associated with plasma detachment in JT-60U

    International Nuclear Information System (INIS)

    Hatayama, A.; Hoshino, K.; Miyamoto, K.

    2003-01-01

    Recent new results of the high Mach flows associated with plasma detachment are presented on the basis of numerical simulations by a 2-D edge simulation code (the B2-Eirene code) and their comparisons with experiments in JT-60U W-shaped divertor plasma. High Mach flows appear near the ionization front away from the target plate. The plasma static pressure rapidly drops, while the total pressure is kept almost constant near the ionization front, because the ionization front near the X-point is clearly separated from the momentum loss region near the target plate. Redistribution from static to dynamic pressure without a large momentum loss is confirmed to be a possible mechanism of the high Mach flows. It has been also shown that the radial structure of the high Mach flow near the X point away from the target plate has a strong correlation with the DOD (Degree of Detachment) at the target plate. Also, we have made systematic analyses on the high Mach flows for both the 'Open' geometry and the 'W-shaped' geometry of JT-60U in order to clarify the geometric effects on the flows. (author)

  9. Evaluation of N-Acetyl Cysteine performance in acetaminophen poisoning using certain liver and renal factors in plasma

    Directory of Open Access Journals (Sweden)

    Armin Salek Maghsoudi

    2014-10-01

    Full Text Available Background: Annually, acetaminophen poisoning causes probable acute liver and renal failures in different societies. N-acetyl cystein (NAC, first suggested as an effective antidote to fight against acetaminophen poisoning in 1970, prevents the binding of NAPQI to hepatic cells. Methods: In the present study 30 patients with the average age of 27 and acetaminophen poisoning who referred to the poisons unit of Sina hospital in Tabriz were selected as the study sample. During the 24 hours of hospitalization, the blood samples of the patients were taken and collected in heparinized tubes. The plasma was separated by centrifuge and kept in tubes in -70°C until it was analyzed by a high performance liquid chromatography method (HPLC and laboratory analytical kits. Results: the glutathione peroxidase (GPX activity difference between the patients and control group was significant at first (P0.05. Conclusion: The activity level of GPX changed before a tangible change in regular liver enzymes. Urea level increased after 24 hours of treatment despite serum therapy and hydration condition.

  10. Monocyte and plasma expression of TAM ligand and receptor in renal failure: Links to unregulated immunity and chronic inflammation.

    Science.gov (United States)

    Lee, Iris J; Hilliard, Brendan A; Ulas, Mehriban; Yu, Daohai; Vangala, Chandan; Rao, Swati; Lee, Jean; Gadegbeku, Crystal A; Cohen, Philip L

    2015-06-01

    Chronic inflammation is increased in patients with chronic kidney disease (CKD) and contributes to cardiovascular morbidity and mortality. Specific immune mechanisms and pathways that drive and maintain chronic inflammation in CKD are not well described. The TAM ligands (Gas6 and protein S) and receptors (Axl and Mer) have been recently recognized as playing a prominent role in immune regulation. The receptors exist in both soluble and cell-bound forms; the soluble receptors (sAxl and sMer) are believed to compete with the bound receptors and thus inhibit their function. In this study, we determined the expression of cell-bound and soluble TAM proteins in patients with CKD. CKD patients had significantly lower expression of Mer in monocytes, yet increased expression of soluble TAM receptors sAxl and sMer in plasma compared to controls. The metalloproteinase ADAM 17, responsible for cleavage of Mer to its soluble form, was increased in patient monocytes. Elevated levels of soluble TAM receptors were more evident in patients with progressive renal failure. These observations suggest that functional deficiency of TAM receptor-mediated regulation of inflammation may contribute to chronic inflammation in patients with CKD. Copyright © 2015 Elsevier Inc. All rights reserved.