WorldWideScience

Sample records for carbon-14 urea breath

  1. Validation of ten-minute single sample carbon-14 urea breath test for diagnosis of Helicobacter pylori infection

    Energy Technology Data Exchange (ETDEWEB)

    Prabakaran, K.; Fernandes, V.; McDonald, J. [Illawarra Regional Hospital, Wollongong, NSW (Australia). Depts of Nuclear Medicine and Gastroenterology

    1996-09-01

    Helicobacter pylori infection is traditionally diagnosed by endoscopy followed by gastric biopsy and histologic demonstration of organisms, rapid urease test and culture. The non-invasive carbon-14-urea breath test has been widely accepted now for the diagnosis of this bacterium. This study was aimed to establish and validate normal and abnormal values for an Australian population, for a single sample carbon-14-urea breath test at ten minutes. A dose of 185 kBq was used in order to achieve reasonable counting statistics. The derived values were validated with the results of the rapid urease test. This method has a high sensitivity, specificity and greater patient acceptance, and could be used in many clinical settings as the first modality for the diagnosis of H. pylori infection and for documenting response or cure after antibiotic therapy for eradication. 11 refs., 1 tab., 4 figs.

  2. Validation of a simplified carbon-14-urea breath test for routine use for detecting Helicobacter pylori noninvasively

    Energy Technology Data Exchange (ETDEWEB)

    Henze, E.; Malfertheiner, P.; Clausen, M.; Burkhardt, H.; Adam, W.E. (Univ. of Ulm (West Germany))

    1990-12-01

    A carbon-14 ({sup 14}C) urea breath test for detecting Helicobacter pylori with multiple breath sampling was developed. Carbon-14-urea (110 kBq) administered orally to 18 normal subjects and to 82 patients with Helicobacter infection. The exhaled {sup 14}C-labeled CO{sub 2} was trapped at 10-min intervals for 90 min. The total {sup 14}C activity exhaled over 90 min was integrated and expressed in %activity of the total dose given. In normals, a mean of 0.59% +/- 0.24% was measured, resulting in an upper limit of normal of 1.07%. In 82 patients, a sensitivity of 90.2%, a specificity of 83.8%, and a positive predictive value of 90.2% was found. The single probes at intervals of 40-60 min correlated best with the integrated result, with r ranging from 0.986 to 0.990. The test's diagnostic accuracy did not change at all when reevaluated with the 40-, 50-, or 60-min sample data alone. Thus, the {sup 14}C-urea breath test can be applied routinely as a noninvasive, low-cost and one-sample test with high diagnostic accuracy in detecting Helicobacter pylori colonization.

  3. Carbon-14 urea breath test for the diagnosis of Campylobacter pylori associated gastritis

    Energy Technology Data Exchange (ETDEWEB)

    Marshall, B.J.; Surveyor, I.

    1988-01-01

    Urease in the human gastric mucosa is a marker for infection with Campylobacter pylori (CP), an organism suspected of causing chronic gastritis and peptic ulceration. To detect gastric urease, we examined 32 patients who were being evaluated for possible peptic ulcer disease. Fasting patients were given 10 microCi (370 kBq) of /sup 14/C-labeled urea. Breath samples were collected in hyamine at intervals between 1 and 30 min. The amount of /sup 14/C collected at these times was expressed as: body weight X (% of administered dose of /sup 14/C in sample)/(mmol of CO/sub 2/ collected). The presence of C. pylori colonization was also determined by examination of multiple endoscopic gastric biopsy specimens. On average, patients who were proven to have C. pylori infection exhaled 20 times more labeled CO/sub 2/ than patients who were not infected. The difference between infected patients and C. pylori negative control patients was highly significant at all time points between 2 and 30 min after ingestion of the radionuclide (p less than 0.0001). The noninvasive urea breath is less expensive than endoscopic biopsy of the stomach and more accurate than serology as a means of detecting Campylobacter pylori infection. Because the test detects actual viable CP organisms, it can be used to confirm eradication of the bacterium after antibacterial therapy.

  4. Biokinetics and radiation doses for carbon-14 urea in adults and children undergoing the Helicobacter pylori breath test

    Energy Technology Data Exchange (ETDEWEB)

    Leide-Svegborn, S.; Olofsson, M.; Mattsson, S.; Nosslin, B.; Pau, K. [Department of Radiation Physics, Lund University, Malmoe University Hospital, Malmoe (Sweden); Stenstroem, K.; Erlandsson, B.; Hellborg, R. [Department of Nuclear Physics, Lund University, Lund (Sweden); Nilsson, L. [Department of Clinical Physiology, Lund University, Malmoe University Hospital, Malmoe (Sweden); Johansson, L. [Department of Radiation Physics, Umeaa University, Umeaa University Hospital, Umeaa (Sweden); Skog, G. [Radiocarbon Dating Laboratory, Department of Quaternary Geology, Lund University, Lund (Sweden)

    1999-06-01

    The long-term biokinetics and dosimetry of carbon-14 were studied in nine adults and eight children undergoing carbon-14 urea breath test for Helicobacter pylori (HP) infection. The elimination of {sup 14}C via exhaled air and urine was measured with the liquid scintillation counting technique and with accelerator mass spectrometry. After the subjects had been given 110 kBq {sup 14}C-urea (children: 55 kBq) orally, samples of exhaled air were taken up to 180 days after administration and samples of urine were collected up to 40 days. Sixteen of the subjects were found to be HP-negative. In these subjects a total of 91.1%{+-}3.9% (mean of adults and children {+-} standard error of the mean) of the administered {sup 14}C activity was recovered. The majority of the administered activity, 88.3%{+-}6.2% in adults and 87.7%{+-}5.0% in children, was excreted via the urine within 72 h after administration. A smaller fraction was exhaled. In adults 4.6%{+-}0.6% of the activity was exhaled within 20 days and in children 2.6%{+-}0.3%. Uncertainties in the biokinetic results are mainly due to assumptions concerning endogenous CO{sub 2} production and urinary excretion rate and are estimated to be less than 30%. The absorbed dose to various organs and the effective dose were calculated using the ICRP model for urea and CO{sub 2}. The urinary bladder received the highest absorbed dose: in adults, 0.15{+-}0.01 mGy/MBq and in children of various ages (7-14 years), 0.14-0.36 mGy/MBq. The findings indicate that an investigation with {sup 14}C-urea gives an effective dose to adults of 2.1{+-}0.1 {mu}Sv (for 110 kBq) and to children of 0.9-2.5 {mu}Sv (for 55 kBq). From a radiation protection point of view, there is thus no reason for restrictions on even repeated screening investigations with {sup 14}C-urea in whole families, including children. (orig.) With 5 figs., 4 tabs., 32 refs.

  5. Quantification of Helicobacter pylori infection in gastritis and ulcer disease using a simple and rapid carbon-14-urea breath test

    Energy Technology Data Exchange (ETDEWEB)

    Debongnie, J.C.; Pauwels, S.; Raat, A.; de Meeus, Y.; Haot, J.; Mainguet, P. (Department of Nuclear Medicine, University of Louvain Medical School, Brussels (Belgium))

    1991-06-01

    Gastric urease was studied isotopically in 230 patients with biopsy-proven normal mucosa or chronic gastritis, including 59 patients with ulcer disease. Carbon-14-urea was given in 25 ml of water without substrate carrier or nutrient-dense meal, and breath samples were collected over a 60-min period. The amount of 14CO2 excreted at 10 min was independent of the rate of gastric emptying and was not quantitatively influenced by the buccal urease activity. The 10-min 14CO2 values discriminated well between Helicobacter pylori positive and negative patients (94% sensitivity, 89% specificity) and correlated with the number of organisms assessed by histology. The test was a good predictor of chronic gastritis (95% sensitivity and 96% specificity), and a quantitative relationship was observed between 14CO2 values and the severity and activity of the gastritis. In H. pylori positive patients, breath 14CO2 was found to be similar in patients with and without ulcer disease, suggesting that the number of bacteria is not a determining factor for the onset of ulceration.

  6. Accuracy of a rapid 10-minute carbon-14 urea breath test for the diagnosis of Helicobacter pylori-associated peptic ulcer disease

    Energy Technology Data Exchange (ETDEWEB)

    Kao Chiahung (Taichung Veterans General Hospital (Taiwan, Province of China). Dept. of Nuclear Medicine); Wang Shyhjen (Taichung Veterans General Hospital (Taiwan, Province of China). Dept. of Nuclear Medicine); Hsu Chungyuan (Taichung Veterans General Hospital (Taiwan, Province of China). Dept. of Nuclear Medicine); Lin Wanyu (Taichung Veterans General Hospital (Taiwan, Province of China). Dept. of Nuclear Medicine); Huang Chihkua (Taichung Veterans General Hospital (Taiwan, Province of China). Dept. of Gastroenterology); Chen Granhum (Taichung Veterans General Hospital (Taiwan, Province of China). Dept. of Gastroenterology)

    1993-08-01

    Urease in the human gastric mucosa is a marker for infection with Helicobacter pylori (HP), an organism which is associated with peptic ulcer disease. To detect gastric urease, we examined 184 patients (144 males, 40 females; mean age: 49.8[+-]15.6 years) with suspected peptic ulcer disease. Fasting patients were given orally 5 [mu]Ci of carbon-14 labelled urea. For each patient only one breath sample was collected in hyamine at 10 min. The amount of [sup 14]C collected at 10 min was expressed as follows: (DPM/mmol CO[sub 2] collected)/(DPM administered)x100xbody weight (kg). The presence of HP colonization was determined by examination of multiple endoscopic prepyloric antral biopsy specimens subjected to culture or a rapid urease test. For the purpose of this study, HP-positive patients were defined as those with characteristic bacteria as indicated by a positive result of either the culture or the rapid urease test; HP-negative patients were defined as those with negative findings on both the culture and the rapid urease test. Of the 184 cases, 99 (53.8%) were positive for HP infection, and 85 (46.2%), negative. The sensitivity and specificity of the rapid 10 min [sup 14]C-urea breath test for the diagnosis of HP-associated peptic ulcer disease were evaluated by a receiver operating characteristic (ROC) curve with a variable cut-off value from 1.5 to 4.5. When a cut-off value of 1.5 was selected, the sensitivity was 100% and the specificity, 83.5%; when a cut-off value of 4.5 was selected, the sensitivity was 54.5% and the specificity, 97.6%. (orig.)

  7. Microdose 14C urea breath test for the diagnosis of Helicobacter pylori: a survey in Iranian population

    Directory of Open Access Journals (Sweden)

    Reza Dowlatabadi Bazaz

    2005-01-01

    Full Text Available The carbon -14 urea breath test (UBTis a non-invasive and simple method for the diagnosis of Helicobacter pylori infection. Attempts have been made to use lower doses of 14C-urea in the UBT in order to reduce the radiation risk of the test. The aim of this study was to assess the accuracy of a microdose (1 µCi [37 KBq] 14C-UBT in Iranian population for validation of its diagnostic accuracy against gold standard methods. Eighty and two patients were subjected to upper gastrointestinal endoscopy as well as 14C-UBT in one week. Rapid urease test and histological examinations were used as gold standard. Breath samples were collected 10, 20 and 30 minute after ingestion of 1 µCi of 14C- urea solution and their activities were measured using a scintillation counter and expressed as counts per minute (cpm and disintegration per minute (dpm. Good agreement was observed between the 14C-UBT and gold standard for samples which were collected 20 minutes after 14C-urea administration. The 14CUBT showed 100% sensitivity, 95% specificity, 95.45% positive predictive value, 100% negative predictive value and 97.50% accuracy. The results of this study showed good concordance between the 14C-UBT and invasive methods.

  8. The fate of ingested [sup 14]C-urea in the urea breath test for Helicobacter pylori infection

    Energy Technology Data Exchange (ETDEWEB)

    Munster, D.J.; Chapman, B.A.; Burt, M.J.; Dobbs, B.R.; Allardyce, R.A.; Bagshaw, P.F.; Troughton, W.D.; Cook, H.B. (Christchurch Hospital (New Zealand))

    1993-08-01

    The metabolic fate of the radioactive carbon in the [sup 14]C-urea breath test for Helicobacter pylori was investigated in 18 subjects. After ingestion of labelled urea, breath was sampled for 24 h, and urine was collected for 3 days. Subjects were designated high or low expirers on the basis of their breath counts, and this agreed well with H. pylori serologic analyses. When given 185 or 37 kBq of [sup 14]C-urea, 51% of the label was recovered from the breath of high expirers, and 7% from the breath of low expirers. The mean combined urinary and breath recovery for high expirers was 86%, and for low expirers it was 97%. It is concluded that the long-term retention of [sup 14]C from ingested [sup 14]C-urea is low. The results enable a more accurate estimation to be made of radiation exposure resulting from the [sup 14]C-urea breath test. 16 refs., 3 figs., 2 tabs.

  9. ( sup 14 C)urea breath test for diagnosis of Helicobacter pylori

    Energy Technology Data Exchange (ETDEWEB)

    Ormand, J.E.; Talley, N.J.; Carpenter, H.A.; Shorter, R.G.; Conley, C.R.; Wilson, W.R.; DiMagno, E.P.; Zinsmeister, A.R.; Phillips, S.F. (Mayo Clinic, Rochester, MN (USA))

    1990-07-01

    H. pylori is a potent urease producer, a characteristic that has been exploited in the development of the (14C)- and (13C)urea breath tests. The prevalence of H. pylori infection also is known to increase with advancing age; however, the individual patient's age has not routinely been considered when interpreting urea breath test results. The aim of this study was to validate a short, age-adjusted (14C)urea breath test for use in diagnosing H. pylori infections. Forty-one subjects (28 volunteers, 13 patients) underwent esophagogastroduodenoscopy with biopsies. Subjects were defined as being H. pylori-positive if histology or culture was positive. In addition, all subjects completed a 120-min (14C)urea breath test. A logistic regression analysis adjusting for age was used to estimate the probability of H. pylori positivity as a function of the 14C values generated. Sixteen subjects were H. pylori-positive, and 25 were H. pylori-negative. The 14C values generated between 15 and 80 min were found to be equally predictive in identifying H. pylori-positive subjects. Advancing age was associated with a higher probability of H. pylori-positivity. By taking advantage of the statistical probabilities, older patients could be accurately diagnosed with H. pylori at lower 14C values. We found that (14C)urea breath test to be both a sensitive and specific test that can be abbreviated to a 30-min examination (total test time). Moreover, our mathematical model indicates that a patient's age should be considered in order to optimize interpretation of the (14C)urea breath test, although further observations are needed to confirm this model.

  10. sup 14 C-urea breath test for the detection of Helicobacter pylori

    Energy Technology Data Exchange (ETDEWEB)

    Veldhuyzen van Zanten, S.J.; Tytgat, K.M.; Hollingsworth, J.; Jalali, S.; Rshid, F.A.; Bowen, B.M.; Goldie, J.; Goodacre, R.L.; Riddell, R.H.; Hunt, R.H. (McMaster Univ., Hamilton, Ontario (Canada))

    1990-04-01

    The high urease activity of Helicobacter pylori can be used to detect this bacterium by noninvasive breath tests. We have developed a {sup 14}C-urea breath test which uses 5 microCi {sup 14}C with 50 mg nonradioactive urea. Breath samples are collected at baseline and every 30 min for 2 h. Our study compared the outcome of the breath test to the results of histology and culture of endoscopically obtained gastric biopsies in 84 patients. The breath test discriminated well between the 50 positive patients and the 34 patients negative for Helicobacter pylori: the calculated sensitivity was 100%, specificity 88%, positive predictive value 93%, and negative predictive value 100%. Treatment with bismuth subsalicylate and/or ampicillin resulted in lower counts of exhaled {sup 14}CO{sub 2} which correlated with histological improvement in gastritis. The {sup 14}C-urea breath test is a better gold standard for the detection of Helicobacter pylori than histology and/or culture.

  11. {sup 14}C urea breath test kit- an evaluation of a compact, cost-effective kit for the detection of H. pylori

    Energy Technology Data Exchange (ETDEWEB)

    Bellon, M.S. [Royal Adelaide Hospital, SA (Australia). Dept of Nuclear Medicine

    1998-03-01

    Full text: Helicobacter pylori infection of the gastric mucosa causes active chronic gastritis and peptic ulceration. Carbon-14 urea breath testing has been well documented in its ability to detect the presence of H. pylori. The aims of this study were to evaluate and refine the test to substantially reduce costs and improve its simplicity, availability and accuracy. We reviewed the results of 138 patients who underwent {sup 14}C urea breath testing for the detection of H. pylori utilising a kit developed at the Royal Adelaide Hospital. Modifications to the standard technique that were assessed included the relevance of buccal cleansing, single sample v multiple sampling, use of alternative CO{sub 2} absorbers and sampling techniques. In those patients with positive biopsy results, a test sensitivity of 100% was achieved. No buccal cleansing is necessary (45% oral contamination without brushing teeth v 41% with). A single breath sample only at 15 min resulted in 100% sensitivity. Alternative (cheaper and safer) CO{sub 2} absorbers such as KOH can be used. Based on these results, modifications to this well documented test have enabled us to substantially reduce costs, improve simplicity and safety and increase accuracy and availability of the test for the detection of Helicobacter pylori.

  12. Dosimetry and reproducibility of a capsule-based C-14 urea breath test

    Energy Technology Data Exchange (ETDEWEB)

    Combs, M.J.; Stubbs, J.B.; Buck, D.A. [Univ. of Virginia, Charlottesville, VA (United States)]|[Oak Ridge Inst. for Science and Education, TN (United States)] [and others

    1995-05-01

    The aims of this study were (1) to determine the excretion of the C-14 and associated radiation dose and (2) to examine the reproducibility of a commercial C-14 urea breath test for H.pylori diagnosis. Tests were performed on twenty consenting volunteers (13M, 7F, 24-48 yr). Breath samples containing 1 mmol CO{sub 2} were obtained at 0,5,10,15,20,25,30 min. and 1,2,3,4,5,6,12, 24 hrs following administration of the 37kBq C-14 urea test capsule. A 24 hr urine collection was performed with each voiding collected separately. A repeat breath test was performed 24 hr after the first. H. pylori positive (HP+) was defined as a 15 minute breath sample >=50 dpm. Total urine excretion was obtained directly. Breath excretion was modeled by estimating the area under the excretion curve and using a constant factor of 884 mmol CO{sub 2}/ hr. Urine and breath excretion data in HP+ and H. pylori-negative (HP-) volunteers were pooled and fit to a monoexponential function thus estimating the cumulative urinary excretion of unmetabolized urea. Previously reported biokinetic models of C-14 urea and bicarbonate were used to estimate radiation doses form each compound. Weighted sums were calculated for each dose estimate using each group`s excretion fraction distribution. Both HP+ and HP- volunteers excreted an average of 73% of the C-14 over the first 24 hr. HP+ excretion was evenly divided between breath (34%) and urine (38%). HP-excretion is almost solely by the urinary pathway. The maximum dose for HP= was to the red marrow (0.0033 mGy) and a maximum of 0.0054 mGy to the urinary bladder wall for HP-. There was no difference between 15 inch breath samples on the two days (t-test, p>0.6). The minimum HP+ result at 15 inch was 270 dpm and the maximum HP- result at 15 inch was 18 dpm, indicating great separation between HP+ and HP- results. This study verifies previous dose estimates using C-14 excretion data. The test is sensitive and reproducible with a low radiation dose.

  13. Validation of {sup 14} C-urea breath test for diagnosis of Helicobacter pylori

    Energy Technology Data Exchange (ETDEWEB)

    Mattar, Rejane; Silva, Fernando Marcuz; Alexandrino, Ana Maria; Laudanna, Antonio Atilio [Sao Paulo Univ., SP (Brazil). Hospital das Clinicas. Dept. de Gastroenterologia]. E-mail: shiroineko@uol.com.br

    1999-02-01

    The aim of this study was to validate the {sup 14} C-urea breath test for use in diagnosis of Helicobacter pylori infection. Thirty H. pylori positive patients, based on histologic test and thirty H. pylori negative patients by histology and anti-H pylori IgG entered the study. Fasting patients drank 5 uCi of {sup 14} C-urea in 20 ml of water. Breath samples were collected at O, 5, 10, 15, 20 and 30 min. The difference of cpm values between the two groups was significant at all the time intervals, besides time 0 (p < 0.0001). At 20 min, the test gave 100% sensitivity and specificity with a cut-off value of 562 cpm. Females were higher expirers than males (p=0.005). {sup 14} C-urea breath test is highly accurate for Helicobacter pylori diagnosis. It is fast, simple and should be the non-invasive test used after treating Helicobacter pylori infection. (author)

  14. Does low dose13C-urea breath test maintain a satisfactory accuracy in diagnosing Helicobacter pylori infection?

    Directory of Open Access Journals (Sweden)

    Luiz Gonzaga Vaz Coelho

    2011-06-01

    Full Text Available CONTEXT: The standard doses of 13C-urea in 13C-urea breath test is 75 mg. OBJECTIVE: To assess the diagnostic accuracy of 13C-urea breath test containing 25 mg of 13C-urea comparing with the standard doses of 75 mg in the diagnosis of Helicobacter pylori infection. METHODS: Two hundred seventy adult patients (96 males, 174 females, median age 41 years performed the standard 13C-urea breath test (75 mg 13C-urea and repeated the 13C-urea breath test using only 25 mg of 13C-urea within a 2 week interval. The test was performed using an infrared isotope analyzer. Patients were considered positive if delta over baseline was >4.0‰ at the gold standard test. RESULTS: One hundred sixty-one (59.6% patients were H. pylori negative and 109 (40.4% were positive by the gold standard test. Using receiver operating characteristic analysis we established a cut-off value of 3.4% as the best value of 25 mg 13C-urea breath test to discriminate positive and negative patients, considering the H. pylori prevalence (95% CI: 23.9-37.3 at our setting. Therefore, we obtained to 25 mg 13C-urea breath test a diagnostic accuracy of 92.9% (95% CI: 88.1-97.9, sensitivity 83.5% (95% CI: 75.4-89.3, specificity 99.4% (95% CI: 96.6-99.9, positive predictive value 98.3% (95% CI: 92.4-99.4, and negative predictive value 93.0% (95% CI: 88.6-96.1. CONCLUSIONS: Low-dose 13C-urea breath test (25 mg 13C-urea does not reach accuracy sufficient to be recommended in clinical setting where a 30% prevalence of H. pylori infection is observed. Further studies should be done to determine the diagnostic accuracy of low doses of 13C-urea in the urea breath test.

  15. Accuracy of the {sup 14} C-urea breath test for the diagnosis of Helicobacter pylori

    Energy Technology Data Exchange (ETDEWEB)

    Gomes, Ana Thereza Britto [Bahia Univ., Salvador (Brazil). Faculdade de Medicina; Coelho, Luciano Kowalsky [Faculdade de Medicina de Blumenau, SC (Brazil); Secaf, Marie [Sao Paulo Univ., Ribeirao Preto, SP (Brazil). Faculdade de Medicina. Hospital das Clinicas; Modena, Jose Luiz Pimenta; Troncon, Luiz Ernesto de Almeida; Oliveira, Ricardo Brandt de [Sao Paulo Univ., Ribeirao Preto, SP (Brazil). Faculdade de Medicina

    2002-05-01

    The development of simple, accurate and low-expense techniques for detection of Helicobacter pylori infection has great relevance. The objective was to determine the accuracy of a rapid {sup 14} C-urea breath test (UBT) employing a very simple device for breathed air collection. One hundred and thirty-seven adult patients who underwent upper gastrointestinal endoscopy in the Clinical Hospital. The main measurements were histology for Helicobacter pylori (HP); urease test; urea breath test (UBT). One hundred and fifteen patients were infected by HP (HP +) according to both histology and the urease test, and 22 patients were HP-negative (HP-), according to the same two tests. UBT was capable of discriminating between HP + and HP- in a way that was similar to the combination of urease test and histology. When this combination of results is taken as the 'gold standard' for HP infection, the sensitivity and specificity of UBT are both greater than 90% for a range of cut-off points and breathed air collection times. It was concluded that the rapid UBT employing a simple device for air collection has a high accuracy in determining HP infection. (author)

  16. 14C-urea breath test in patients undergoing anti-tuberculosis therapy

    Institute of Scientific and Technical Information of China (English)

    Sayed Amir Mirbagheri; Amir Ali Sohrabpour; Mehrdad Hasibi; Babak Moghimi; Mehdi Mohamadnejad

    2005-01-01

    AIM: Urea breath test (UBT) is a non-invasive diagnostic test for detecting the presence of Helicobacter pylori(H pylori).In this study we evaluated the effect of anti-tuberculosis therapy on the results of 14C-UBT.METHODS: Patients, with the diagnosis of tuberculosis (TB) who had a positive UBT at the point of starting antiTB therapy, were included. None had a history of peptic ulcer disease or had taken antibiotics, bismuth compounds and/or PPI in the previous month, 14C-UBT was repeated at the end of the second month and the end of treatment period and one month after completion of treatment course.RESULTS: Thirty-five patients (23 males) were enrolled.14C-UBT was negative in all 35 patients (100%) at the end of the second month and remained negative in 30cases (85.7%) at the end of the treatment course. One month after completion of treatment course, UBT remained negative in 13 patients (37.1%).CONCLUSION: Our report underscores the need for caution while interpreting urea breath test results in patients undergoing anti-TB therapy. Furthermore, the combination of drugs used in this study resulted in H pylori eradication in a minority of patients.

  17. An optimized 13C-urea breath test for the diagnosis of H pylori infection

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    AIM: To validate an optimized 13C-urea breath test (13C-UBT) protocol for the diagnosis of-H pylori infection that is cost-efficient and maintains excellent diagnostic accuracy.METHODS: 70 healthy volunteers were tested with two simplified 13C-UBT protocols, with test meal (Protocol 2)and without test meal (Protocol 1). Breath samples were collected at 10, 20 and 30 min after ingestion of 50 mg 13C-urea dissolved in 10 mL of water, taken as a single swallow, followed by 200 mL of water (pH 6.0) and a circular motion around the waistline to homogenize the urea solution. Performance of both protocols was analyzed at various cut-off values. Results were validated against the European protocol.RESULTS: According to the reference protocol, 65.7% individuals were positive for H pylori infection and 34.3% were negative. There were no significant differences in the ability of both protocols to correctly identify positive and negative H pylori individuals. However, only Protocol 1 with no test meal achieved accuracy, sensitivity,specificity, positive and negative predictive values of 100%. The highest values achieved by Protocol 2 were 98.57%, 97.83%, 100%, 100% and 100%, respectively.CONCLUSION: A 10 min, 50 mg 13C-UBT with no test meal using a cut-off value of 2-2.5 is a highly accurate test for the diagnosis of H pylori infection at a reduced cost.

  18. Validation of the 13C-urea breath test for use in cheetahs (Acinonyx jubatus) with Helicobacter.

    Science.gov (United States)

    Chatfield, Jenifer; Citino, Scott; Munson, Linda; Konopka, Stanley

    2004-06-01

    Historically, therapeutic monitoring for prescribed eradication treatment of Helicobacter in cheetahs (Acinonyx jubatus) with associated gastritis has been accomplished only through endoscopic biopsies. The 13C-urea breath test (UBT) can offer an alternative to repeated biopsies for therapeutic monitoring. Five male and five female cheetahs and one male Sumatran tiger (Panthera tigris) were studied. All were clinically healthy before and after this investigation. Breath samples of end-tidal expiration were taken before and after administration of a 13C-enriched urea solution through a gastroesophageal tube. Twenty-milliliter breath samples were taken at 10, 20, 30, and 40 min after administration of the urea solution. The results of the breath analysis were compared with the results of rapid urease testing, histopathologic examination, and impression smears of gastric biopsies taken at the time of the breath test. The sensitivity and specificity for the 13C-UBT in this investigation were 100%. and the positive predictive value and negative predictive value were both 100%. Although the 13C-UBT is a good noninvasive diagnostic tool for monitoring the presence of Helicobacter sp. in the gastric mucosa, endoscopy should still be used for initial diagnosis and grading of gastritis and for monitoring the progression of disease in cheetahs. The 13C-UBT is a valuable, simple, accurate, and sensitive tool for monitoring eradication of Helicobacter during therapy for clinical gastritis.

  19. Follow up of serial urea breath test results in patients after consumption of antibiotics for non-gastric infections

    Institute of Scientific and Technical Information of China (English)

    Wai-Keung Leung; Lawrence Cheung-Tsui Hung; Carrie Ka-Li Kwok; Rupert Wing-Loong Leong; Daniel Kwok-Keung Ng; Joseph Jao-Yiu Sung

    2002-01-01

    AIM: The widespread use of antibacterial therapy hasbeen suggested to be the cause for the decline in theprevalence of Helicobacter pyloriinfection. This studyexamine the serial changes of urea breath test resultsin a group of hospitalized patients who were givenantibacterial therapy for non-gastric infections.METHODS: Thirty-five hospitalized patients who weregiven antibacterial therapy for clinical infections,predominantly chest and urinary infections, werestudied. Most (91%) patients were given singleantibiotic of either a penicillin or cephalosporin group.Serial 13C-urea breath tests were performed within 24hours of initiation of antibiotics, at one-week and atsix-week post-therapy. H. pylori infection wasdiagnosed when one or more urea breath tests waspositive.RESULTS: All 35 patients completed three serial ureabreath tests and 26 (74 %) were H. pylori-positive. Ten(38 %) H. pylori-infected patients had at least onenegative breath test results during the study period.The medium delta 13C values were significantly lowerat baseline (8.8) than at one-week (20.3) and six-week(24.5) post-treatment in H. pylori-positive individuals(P=0.022). Clearance of H. pyloriat six-week was onlyseen in one patient who had received anti-helicobactertherapy from another source.CONCLUSION: Our results suggested that one-third ofH. pylori-infected individuals had transient false-negative urea breath test results during treatment withantibacterial agent. However, clearance of H. pyloriinfection by regular antibiotic consumption is rare.

  20. 13[C]-urea breath test as a novel point-of-care biomarker for tuberculosis treatment and diagnosis.

    Directory of Open Access Journals (Sweden)

    Mandeep S Jassal

    Full Text Available BACKGROUND: Pathogen-specific metabolic pathways may be detected by breath tests based on introduction of stable isotopically-labeled substrates and detection of labeled products in exhaled breath using portable infrared spectrometers. METHODOLOGY/PRINCIPAL FINDINGS: We tested whether mycobacterial urease activity could be utilized in such a breath test format as the basis of a novel biomarker and diagnostic for pulmonary TB. Sensitized New-Zealand White Rabbits underwent bronchoscopic infection with either Mycobacterium bovis or Mycobacterium tuberculosis. Rabbits were treated with 25 mg/kg of isoniazid (INH approximately 2 months after infection when significant cavitary lung pathology was present. [(13C] urea was instilled directly into the lungs of intubated rabbits at selected time points, exhaled air samples analyzed, and the kinetics of delta(13CO(2 formation were determined. Samples obtained prior to inoculation served as control samples for background (13CO(2 conversion in the rabbit model. (13CO(2, from metabolic conversion of [(13C]-urea by mycobacterial urease activity, was readily detectable in the exhaled breath of infected rabbits within 15 minutes of administration. Analyses showed a rapid increase in the rate of (13CO(2 formation both early in disease and prior to treatment with INH. Following INH treatment, all evaluable rabbits showed a decrease in the rate of (13CO(2 formation. CONCLUSIONS/SIGNIFICANCE: Urea breath testing may provide a useful diagnostic and biomarker assay for tuberculosis and for treatment response. Future work will test specificity for M. tuberculosis using lung-targeted dry powder inhalation formulations, combined with co-administering oral urease inhibitors together with a saturating oral dose of unlabeled urea, which would prevent the delta(13CO(2 signal from urease-positive gastrointestinal organisms.

  1. Capsule 13C-urea breath test for the diagnosis of Helicobacter pylori infection

    Institute of Scientific and Technical Information of China (English)

    Nan-Jing Peng; Ping-I Hsu; Kwok-Hung Lai; Ren-Shyan Liu; Shui-Cheng Lee; Daw-Guey Tsay; Ching-Chu Lo; Huei-Hwa Tseng; Wen-Keui Huang; Gin-Ho Lo

    2005-01-01

    AIM: To compare the accuracy of capsule 13C-urea breath test (UBT) with conventional invasive methods for the diagnosis of Helicobacter pylori infection.METHODS: One hundred patients received CLO test,histological examination, culture and 100- or 50-mg capsule UBT for the diagnosis of Hpyloriinfection. Hpylori infection was defined as those with positive culture or positive results from both histology and CLO test.RESULTS: Both the sensitivity and specificity of the 100-mg capsule UBT (n = 50) were 100%. The sensitivity and specificity of the 50-mg capsule UBT (n = 50) were 96.4and 100%, respectively. Taken together, the accuracy of capsule UBT (n=100) was higher than that of CLO test,histology and culture (100% vs 92%, 91% and 89%,respectively; P= 0.035, 0.018 and 0.005, respectively). Our data showed that the optimal timing of sampling for 100-and 50-mg capsule UBT was 15-30 and 6-15 min, respectively.CONCLUSION: Capsule UBT has a higher accuracy compared with biopsy-based tests. It is an ideal method for the diagnosis of Hpyloriinfection.

  2. {sup 13}C-urea breath test analyzed with infrared isotope spectrometry for the diagnosis of Helicobacter pylori; {sup 13}C-urea-pusteproeve som dagnostisk metode ved Helicobacter pylori-infeksjon

    Energy Technology Data Exchange (ETDEWEB)

    Dahlberg, M.; Schoensby, H. [Aker Sykehus, Oslo (Norway)

    1998-10-01

    The authors have evaluated a {sup 13}C-urea breath test for the diagnosis of Helicobacter pylori infection. The {sup 13}C-test was analyzed with isotope-selective non-dispersive infrared spectrometry and compared with a {sup 14}C-urea breath test and the urease test in gastric mucosal biopsies. 46 patients were analyzed with breath tests, 23 patients were negative and 22 patients were positive with both methods. One patients was positive with {sup 14}C-method and negative with the {sup 13}C-urea breath test. 61 patients were analyzed with the {sup 13}C-urea breath test and the urease test. 30 patients were negative and 30 patients were positive with both methods, whereas one patient with a negative urease test had a positive breath test. {sup 13}C-urea breath test analyzed with isotope-selective non-dispersive infrared spectrometry is a fast, simple, non-radioactive, non-invasive, convenient and reliable method for the diagnosis of Helicobacter pylori infection. 12 refs., 2 figs., 1 tab.

  3. Nondispersive isotope-selective infrared spectroscopy: A new analytical method for {sup 13}C-urea breath tests

    Energy Technology Data Exchange (ETDEWEB)

    Braden, B.; Schaefer, F.; Caspary, W.F.; Lembcke, B. [Johann Wolfgang Goethe Univ., Frankfurt am Main (Germany)

    1996-05-01

    Currently, stable isotope techniques in breath tests using {sup 13}C-labeled substrates are limited to a few centers equipped with expensive and complex isotope spectrometry (IRMS). Although breath samples can be mailed to these centers, widespread application of {sup 13}C-breath tests would be more feasible with a cheaper and more practicable analysis system at hand. The authors therefore tested the newly developed nondispersive isotope-selective infrared spectrometer (NDIRS) with reference to IRMS in a clinical setting, comparing the results of both techniques in 538 consecutive {sup 13}C-urea breath tests performed for the detection of helicobacter pylori infection. With NDIRS five false-positive and three false-negative results were observed; that is, the sensitivity of NDIRS was 98.3%, and the specificity was 98.6%. When running this large number of breath tests in 3 days, the NDIRS proved to be a reliable, stable, and easy-to-operate analytical tool, which is well qualified for gastroenterologic application in the diagnostic routine. Both the price and the easy handling of NDIRS will facilitate the widespread use of the noninvasive stable isotope technique for {sup 13}C breath test. 22 refs., 3 figs., 1 tab.

  4. Dual therapy for third-line Helicobacter pylori eradication and urea breath test prediction

    Institute of Scientific and Technical Information of China (English)

    Toshihiro Nishizawa; Hidekazu Suzuki; Takama Maekawa; Naohiko Harada; Tatsuya Toyokawa; Toshio Kuwai; Masanori Ohara

    2012-01-01

    We evaluated the efficacy and tolerability of a dual therapy with rabeprazole and amoxicillin (AMX) as an empiric third-line rescue therapy.In patients with failure of first-line treatment with a proton pump inhibitor (PPI)-AMX-clarithromycin regimen and second-line treatment with the PPI-AMX-metronidazole regimen,a third-line eradication regimen with mbeprazole (10 mg q.i.d.) and AMX (500 mg q.i.d.) was prescribed for 2 wk.Eradication was confirmed by the results of the 13C-urea breath test (UBT) at 12 wk after the therapy.A total of 46 patients were included; however,two were lost to followup.The eradication rates as determined by per-protocol and intention-to-treat analyses were 65.9% and 63.0%,respectively.The pretreatment UBT results in the subjects showing eradication failure; those patients showing successful eradication comprised 32.9 ± 28.8 permil and 14.8 ± 12.8 permil,respectively.The pretreatment UBT results in the subjects with eradication failure were significantly higher than those in the patients with successful eradication (P =0.019).A low pretreatment UBT result (≤ 28.5 permil) predicted the success of the eradication therapy with a positive predictive value of 81.3% and a sensitivity of 89.7%.Adverse effects were reported in 18.2% of the patients,mainly diarrhea and stomatitis.Dual therapy with rabeprazole and AMX appears to serve as a potential empirical third-line strategy for patients with low values on pretreatment UBT.

  5. Validation of low activity {sup 14}C-urea breath test in diagnosis of ``Helicobacter pylori``in humans

    Energy Technology Data Exchange (ETDEWEB)

    Bielanski, W.; Konturek, S.J.; Dobrzanka, M.J.; Plonka, M.; Sito, E.; Stachura, J. [Uniwersytet Jagiellonski, Cracow (Poland); Hoffman, S.R.; Marshall, B.J. [Tri-Med Specialtis, Charlottenville, VA (United States)

    1996-12-31

    Etiologic role for ``Helicobacter pylori`` (HP) seems to be well established in gastric pathology. The high urease activity of HP can be used to detect this bacterium by non-invasive urea breath tests (UBT). We validated the low activity version of the test in which 37 kBq {sup 14}C-urea is given orally in capsule. With the cut off value {>=} 1.66 Bq (100 DPM) as positive, UBT results correlated highly significant with combined results for invasive methods, i.e. CLO-test + Histology score. The reproducibility of the test was 100%. The results obtained for the breath test performed locally were almost identical with that read at remote laboratory. The data found for fasting and fed states of subjects agreed in 87%. When {sup 14}C-urea was confined in the mouth of both HP positive and HP negative patients UBT showed the presence of urease activity in the mouth cavity. (author). 21 refs, 2 figs, 1 tab.

  6. A new, practical, low-dose {sup 14}C-urea breath test for the diagnosis of Helicobacter pylori infection: clinical validation and comparison with the standard method

    Energy Technology Data Exchange (ETDEWEB)

    Oeztuerk, Emel; Ilgan, Seyfettin; Arslan, Nuri; Oezgueven, Mehmet [Department of Nuclear Medicine, Guelhane Military Medical Academy and Medical School, 06018, Etlik, Ankara (Turkey); Yesilova, Zeki; Erdil, Ahmet; Dagalp, Kemal [Department of Gastroenterology, Guelhane Military Medical Academy and Medical School, Etlik, Ankara (Turkey); Celasun, Buelent [Department of Pathology, Guelhane Military Medical Academy and Medical School, Etlik, Ankara (Turkey); Ovali, Oender [Department of Internal Medicine, Guelhane Military Medical Academy and Medical School, Etlik, Ankara (Turkey); Bayhan, Hikmet [Department of Nuclear Medicine, Acbadem Hospital, Istanbul (Turkey)

    2003-11-01

    The carbon-14 urea breath test (UBT) is a reliable and non-invasive technique for the diagnosis of Helicobacter pylori (HP) infection. In this study we evaluated the diagnostic performance of a new, practical and low-dose {sup 14}C-UBT system for the diagnosis of HP and compared the results with those obtained using the standard method. Seventy-five patients (56 female, 19 male) with dyspepsia underwent {sup 14}C-UBT and endoscopy with antral biopsies for histological analysis. The rapid urease test (CLO test) was applied to 50 of these patients. After a 6-h fasting period, a 37-kBq {sup 14}C-urea capsule was swallowed for UBT. Breath samples were collected and counted using two different methods, the Heliprobe method and the standard method. In the Heliprobe method, patients exhaled into a special dry cartridge system (Heliprobe BreathCard) at 10 min. The activities of the cartridges were counted using a designated small GM counter system (Heliprobe analyser). Results were expressed both as counts per minute (HCPM) and as grade (0, not infected; 1, equivocal; 2, infected) according to the counts. In the standard method, breath samples were collected by trapping in a liquid CO{sub 2} absorber. Radioactivity was counted as disintegrations per minute (SDPM) using a liquid scintillation counter after addition of a liquid scintillation cocktail. Histological examination was used as a gold standard. Two patients were excluded from the study because of inadequate biopsy sampling. Forty-eight patients (65%) were found to be HP positive on histology. The Heliprobe method correctly classified 48 of 48 HP-positive patients and 19 of 25 HP-negative patients (sensitivity 100%, specificity 76%, PPV 88%, NPV 100%, accuracy 91%). The standard method correctly classified 48 of 48 HP-positive patients and 20 of 25 HP-negative patients (sensitivity 100%, specificity 80%, PPV 90%, NPV 100%, accuracy 93%). On the other hand, the CLO test identified 26 of 32 HP-positive and 12 of 16 HP

  7. Investigation of the association between glaucoma and Helicobacter pylori infection using the {sup 14}C-urea breath test

    Energy Technology Data Exchange (ETDEWEB)

    Tuzcu, Esra Ayhan; Aydogan, Fusun; Motor, Vicdan Koksaldi; Ilhan, Ozgur; Daglioglu, Mutlu Cihan; Coskun, Mesut; Parlakfikirer, Nihan; Keskin, Ugurcan, E-mail: drayhant@hotmail.com [Medical Faculty, Mustafa Kemal University, Hatay (Turkey)

    2015-07-01

    Purpose: to investigate the association between glaucoma and Helicobacter pylori infection by evaluating for the presence of H. pylori infection in patients with glaucoma using the 14C-urea breath test (14C-UBT). Methods: Using 14C-UBT, H. pylori infection positivity was compared between a group of patients with primary open-angle glaucoma and a control group with normal intraocular pressure and a normal optic disc or normal perimetry. Results: the 14C-UBT was positive in 18 (51.42%) out of 35 patients in the glaucoma group and in 15 (42.85%) out of 35 patients in the control group. H. pylori infection positivity rates were similar between the glaucoma and control groups (p>0.05). Conclusion: according to the 14C-UBT, there is no association between primary open-angle glaucoma and H. pylori infection. (author)

  8. A simplified 13C-Urea breath test (13C-UBT) in the diagnosis of Helicobacter pylori (HP) infection

    Energy Technology Data Exchange (ETDEWEB)

    Rahman, T.; Bartholomeusz, F.D. L.; Bellon, M.S.; Chatterton, B.E. [Royal Adelaide Hospital, Adelaide. SA (Australia). Department of Nuclear Medicine

    1998-06-01

    Full text: The Urea Breath Test (UBT) is an accurate, noninvasive means of assessing the presence of Helicobacter pylori in the stomach. Two tests are currently available, using 13C- and 14C-labelled urea, respectively. 13C is a nonradioactive isotope, unlike 14C, but the 13C-UBT is technically more challenging. The aim of this study was to determine the accuracy of a simplified 13C-UBT with no test meal, using the 14C-UBT as the previously validated standard. 76 studies were performed on 72 patients; 4 patients performed the test twice. 28 patients were female, 44 male. The mean age was 51.1 years (range 23-86 years). 42 patients presented for post-eradication follow up, and 30 for initial diagnosis. All subjects underwent a 14C-UBT with a 15 minute sample. The 13C-UBT was then performed without a test meal and the breath samples obtained at baseline and 20 minutes. Of the 14C-UBT studies, 27 were positive, ranging from 1372 to 10,987 DPM (Normal <1000 DPM), and 49 were negative, range 177-946 DPM. 26 of the 13C-UBT studies were positive, with a Delta value ranging from 4.29-47.89 (Normal: Delta <3.5), and 50 were negative, range -0.20-2.80. There were 1 false-positive and 2 false-negative 13-UBT studies. This yielded a sensitivity of 92.6% and specificity of 98.0% for the simplified 13C-UBT. From these results we conclude that the simplified 13C-UBT is an accurate means of detecting the presence of Helicobacter pylori within the stomach

  9. Performance of Helicobacter pylori acid extract and urease enzyme-linked immunosorbent assays in relation to 14C-urea breath test.

    Science.gov (United States)

    von Wulffen, H; Gatermann, S; Windler, E; Gabbe, E; Heinrich, H C

    1993-09-01

    The 14C-urea breath test has been shown to be a reliable non-invasive method to detect the presence or absence of H. pylori infection. Alternatively, a number of techniques have been devised to detect circulating antibodies against H. pylori in serum, the most commonly used being enzyme-linked immunosorbent assays (ELISA). In the present study we compared the value of two ELISA antigen preparations, an acid glycine extract and a urease preparation, in relation to the results achieved in a 14C-urea breath test. Seventy-five gastroenterology outpatients were screened for the presence of H. pylori infection using the urea breath test. At the same time serum specimens were obtained. Thirty-seven patients had a positive breath test, i.e. they expired more than 2% of the oral 14C test dose within 60 min. Using the breath test as reference, sensitivity and specificity for the acid extract were 89.2% and 84.2% respectively, and for the urease ELISA 81.1% and 89.5%. Agreement between the two ELISAs was found in 82.7%, overall agreement between all three tests was observed in 77.3%. All three tests were found to be useful for monitoring therapy directed against H. pylori.

  10. Validity and cost comparison of "carbon urea breath test for diagnosis of H Pylori in dyspeptic patients

    Institute of Scientific and Technical Information of China (English)

    Shahid Rasool; Shahab Abid; Wasim Jafri

    2007-01-01

    AIM: To validate and compare the cost of microdose 14C urea breath test (UBT) with histology and rapid urease test for the diagnosis of H Pylori.METHODS: Ninety-four consecutive patients with dyspeptic symptoms undergoing gastroscopy were enrolled. Gastric biopsies were taken for histology and rapid urease test. UBT was performed after gastroscopy by microdose "C urea capsules. Sensitivity, specificity and accuracy of UBT were calculated and compared with histology and rapid urease test. Cost comparison of these tests was also performed.RESULTS: H pylori was diagnosed by histology and rapid urease test in 66 (70%) and 61 (65%) patients, while 14C UBT detected infection in 63 (67%). Accuracy of UBT was 93% in comparison with histology while its positive and negative predictive values were 97% and 84%, respectively. Comparison of 14C UBT with rapid urease test gives an accuracy of 96%, with positive and negative predictive values of 95% and 97%, respectively. These results were highly reproducible with a Kappa test (P value < 0.001). Cost of histology or rapid urease test with gastroscopy was 110 USD or 95 USD respectively while the cost of UBT was 15 USD.CONCLUSION: Microdose 14C UBT was comparable to histology and rapid urease test. 14C UBT is an economical, self sufficient and suitable test to diagnose active Hpylori infection in less developed countries.

  11. Can the C-14 urea breath test reflect the extent and degree of ongoing helicobacter pylori infection

    Energy Technology Data Exchange (ETDEWEB)

    Lim, Seok Tae; Sohn, Myung Hee; Lee, Seung Ok; Lee, Soo Taik; Jeong, Myung Ja [Chonbuk National Univ., Chonju (Korea, Republic of)

    2001-02-01

    The C-14 urea breath test (C-14 UBT) is the most specific noninvasive method to detect Helicobacter (H) pylori infection. We investigated if the C-14 UBT can reflect the presence and degree of H. pylori detected by gastroduodenoscopic biopsies (GBx). One hundred fifty patients (M:F=83:67,age 48.6{+-}11.2 yrs) underwent C-14 UBT, rapid urease test (CLO test) and GBx on the same day. For the C-14 UBT, a single breath sample was collected at 10 minutes after ingestion of C-14 urea (137 KBq) capsule and counting was done in a liquid scintillation counter for 1 minute, and the results were classified as positive ({>=}200 dpm), intermediate ( 50 {approx} 199 dpm) or negative ( < 50 dpm). The results of CLO tests were classified as positive or negative according to color change. The results of GBx on giemsa stain were graded 0 (normal) to 4(diffuse) according to the distribution of H. pylori by the Wyatt method. We compared C-14 UBT results with GBx grade as a gold standard. In the assessment of the presence of H. pylori infection, the C-14 UBT global performance yielded sensitivity, specificity, positive predictive value (PPV), negative predictive value (NPV) and accuracy of 92.5%, 88.4%, 97.1%, 88.4% and 91.3%, respectively. However, the CLO test had sensitivity, specificity, PPV, NPV and accuracy of 83.2%, 81.4%, 91.8%, 81.4% and 82.7%, respectively. The quantitative values of the C-14 UBT were 45 {+-} 27 dpm in grade 0, 707 {+-}584 dpm in grade 1, 1558{+-}584 dpm in grade 2, 1851{+-}604 dpm in grade 3, and 2719 {+-} 892 dpm in grade 4. A significant correlation (r=0.848, p<0.01) was found between C-14 UBT and the grade of distribution of H. pylori infection on GBx with giemsa stain. We conclude that the C-14 UBT is a highly accurate, simple and noninvasive method for the diagnosis of ongoing H. pylori infection and reflects the degree of bacterial distribution.

  12. Turnover of carbon in the {sup 13}C-urea breath test for the detection of Helicobacter pylori infection

    Energy Technology Data Exchange (ETDEWEB)

    Costa, Vladimir E.; Andreazzi, Mariana; Cury, Caio S.; Bassetto Junior, Carlos A.Z.; Rodrigues, Maria A.M.; Ducatti, Carlos, E-mail: vladimir@ibb.unesp.br, E-mail: ducatti@ibb.unesp.br, E-mail: mariana.andreazazi@gmail.com, E-mail: caiocury@hotmail.com, E-mail: juniorbassett@hotmail.com, E-mail: mariar@fmb.unesp.br [Universidade Estadual Paulista Julio de Mesquita Filho (UNESP), Botucatu, SP (Brazil)

    2013-07-01

    To obtain a standard protocol for the application of {sup 13}C-urea breath test ({sup 13}C-UBT) analyzed by Isotope Ratio Mass Spectrometer (IRMS) to detect helicobacter pylori infection in the population is necessary to know the behavior of the turnover of {sup 13}C during the test in different individuals. The aims of this study was to find out a pattern for the turnover of the {sup 13}C in the {sup 13}C-UBT, analyzed by IRMS, in patients infected with H. pylori, in a Brazilian population, to define a protocol test application. We found that the isotopic ratio {sup 13}C/{sup 12}C in expired CO{sub 2} from patients infected with H. pylori and subjected to {sup 13}C-UBT does not follow a single pattern of behavior. However this behavior can be similar in subjects having the same maximum values following an inverse proportional relationship between the maximum value and the time of appearance in the curve. (author)

  13. Ten years experience of isotopic breath test with special reference to Helicobacter pylori detection

    Energy Technology Data Exchange (ETDEWEB)

    Verhas, M.; Tricht, L.Van; Verschaeren, A.; Delmotte, E.; Martin, P

    1997-12-31

    The use of the carbon 14 urea breath test by comparison with culture for campylobacter of gastric endoscopic biopsies is studied in 91 patients. They were divided into 2 groups. The first group consisted of 53 patients examined by gastric endoscopy and carbon 14 urea breath test. In this population, gastric biopsies were taken at different regions of the stomach and duodenum. The breath test was performed within 3 hours after endoscopy. The second group consisted of 38 asymptomatic patients whom 23 were parent of children with campylobacter positive gastritis. For the whole population, neither antibiotic therapy nor bismuth medication was administrated within the 15 days before the realization of the test. Results were expressed in % of injected dose/mmole of CO{sub 2} after correction of endogenous production of CO{sub 2}. In conclusion, carbon 14 urea breath test is a reliable noninvasive test for detection and follow-up of gastritis caused by a widespread microorganism. Also, the precision of both tests, {sup 14} C-UBT and {sup 13} C-UBT, are compared simultaneously in 84 adults patients. The results were expressed as % of administered dose expired in 30 minutes. A better precision is observed with the {sup 13} C-UBT

  14. Comparison of the diagnostic performance of {sup 14}C-urea breath test according to counting method for the diagnosis of Helicobacter pylori infection

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Min Woo; Lim, Seok Tae; Lee, Seung Ok; Sohn, Myung Hee [Chonbuk National University Medical School, Chonju (Korea, Republic of)

    2005-02-15

    {sup 14}C-urea breath test (UBT) is a non-invasive and reliable method for the diagnosis of Helicobacter pylon, (HP) infection. In this study, we evaluated the diagnostic performance of a new and rapid {sup 14}C-UBT (Heliprobe method), which was equipped with Geiger-Muller counter and compared the results with those obtained by using the conventional method. Forty-nine patients with dyspepsia underwent gastroduodenoscopy and {sup 14}C-UBT. A 37 KBq {sup 14}C-urea capsule was administered to patients and breath samples were collected. In Heliprobe method, patients exhaled into a Heliprobe BreathCard for 10 min. And then the activities of the BreathCard were countered using Heliprobe analyzer. In the conventional method, results were countered using liquid scintillation counter. During gastroduodenoscopy, 18 of 49 patients were underwent biopsies. According to these histologic results, we evaluated the diagnostic performance of two different methods and compared them. Also we evaluated the concordant and disconcordant rates between them. In all 49 patients, concordant rate of both conventional and Heliprobe methods was 98% (48/49) and the discordant rate was 2% (1/49). thirteen of 18 patients to whom biopsies were applied, were found to be HP positive on histologic results. And both Heliprobe method and conventional method classified 13 of 13 HP-positive patients and 5 of 5 HP-negative patients correctly (sensitivity 100%, specificity 100%, accuracy 100%). The Heliprobe method demonstrated the same diagnostic performance compared with the conventional method and was a simpler and more rapid technique.

  15. Carbon 14 dating; La datation par le carbone 14

    Energy Technology Data Exchange (ETDEWEB)

    Laj, C.; Mazaud, A.; Duplessy, J.C. [CEA Saclay, Lab. des Sciences du Climat et de l' Environnement, 91 - Gif-sur-Yvette (France)

    2004-03-01

    In this article time dating based on carbon 14 method is reviewed, its limits are explained and recent improvements are presented. Carbon 14 is a by-product of the interactions of cosmic protons with air molecules. The fluctuations of the quantity of carbon 14 present in the atmosphere are responsible for the shift observed between the result given by the method and the real age. This shift appears for ages greater than 2000 years and is estimated to 1000 years for an age of 10.000 years. As a consequence carbon 14 dating method requires calibration by comparing with other methods like dendrochronology (till 11.000 years) and time dating of fossil corals (till 26.000 years and soon till 50.000 years). It is assumed that the fluctuations of carbon 14 in the atmosphere are due to: - the changes in the intensity and composition of cosmic radiations itself (due to the motion of the sun system through the galaxy or due to the explosion of a super-novae in the surroundings of the sun system); - the changes of the earth magnetic field that diverts cosmic rays; and - the changes in the interactions between the atmosphere and the oceans knowing that 40 tons of carbon 14 are dissolved in seas while only 1 ton belongs to the atmosphere. (A.C.)

  16. Efficacy and cost-effectiveness of the 13C-urea breath test as the primary diagnostic investigation for the detection of Helicobacter pylori infection compared to invasive and non-invasive diagnostic tests

    Directory of Open Access Journals (Sweden)

    Greiner, Wolfgang

    2009-10-01

    Full Text Available Background: Helicobacter pylori (H. pylori is one of the most common bacterial infections in humans. There is a risk factor for gastric or duodenal ulcers, gastric cancer and MALT (Mucosa Associated Lymphoid Tissue-Lymphomas. There are several invasive and non-invasive methods available for the diagnosis of H. pylori. The 13C-urea breath test is a non-invasive method recommended for monitoring H. pylori eradication therapy. However, this test is not yet used for primary assessment of H. pylori in Germany. Objectives: What are the clinical and health economic benefits of the 13C-urea breath test in the primary assessment of H. pylori compared to other invasive and non-invasive methods? Methods: A systematic literature search including a hand search was performed for studies investigating test criteria and cost-effectiveness of the 13C-urea breath test in comparison to other methods used in the primary assessment of H. pylori. Only studies that directly compared the 13C-urea breath test to other H. pylori-tests were included. For the medical part, biopsy-based tests were used as the gold standard. Results: 30 medical studies are included. Compared to the immunoglobulin G (IgG test, the sensitivity of the 13C-urea breath test is higher in twelve studies, lower in six studies and one study reports no differences. The specificity is higher in 13 studies, lower in three studies and two studies report no differences. Compared to the stool antigen test, the sensitivity of the 13C-urea breath test is higher in nine studies, lower in three studies and one study reports no difference. The specificity is higher in nine studies, lower in two studies and two studies report no differences. Compared to the urease test, the sensitivity of the 13C-urea breath test is higher in four studies, lower in three studies and four studies report no differences. The specificity is higher in five studies, lower in five studies and one study reports no difference. Compared

  17. Application of isotope-selective non-dispersive infrared spectrometry for the evaluation of the 13C-urea breath test: comparison with three concordant methods

    Directory of Open Access Journals (Sweden)

    Coelho L.G.V.

    1999-01-01

    Full Text Available The aim of this work was to compare the performance of isotope-selective non-dispersive infrared spectrometry (IRIS for the 13C-urea breath test with the combination of the 14C-urea breath test (14C-UBT, urease test and histologic examination for the diagnosis of H. pylori (HP infection. Fifty-three duodenal ulcer patients were studied. All patients were submitted to gastroscopy to detect HP by the urease test, histologic examination and 14C-UBT. To be included in the study the results of the 3 tests had to be concordant. Within one month after admission to the study the patients were submitted to IRIS with breath samples collected before and 30 min after the ingestion of 75 mg 13C-urea dissolved in 200 ml of orange juice. The samples were mailed and analyzed 11.5 (4-21 days after collection. Data were analyzed statistically by the chi-square and Mann-Whitney test and by the Spearman correlation coefficient. Twenty-six patients were HP positive and 27 negative. There was 100% agreement between the IRIS results and the HP status determined by the other three methods. Using a cutoff value of delta-over-baseline (DOB above 4.0 the IRIS showed a mean value of 19.38 (minimum = 4.2, maximum = 41.3, SD = 10.9 for HP-positive patients and a mean value of 0.88 (minimum = 0.10, maximum = 2.5, SD = 0.71 for negative patients. Using a cutoff value corresponding to 0.800% CO2/weight (kg, the 14C-UBT showed a mean value of 2.78 (minimum = 0.89, maximum = 5.22, SD = 1.18 in HP-positive patients. HP-negative patients showed a mean value of 0.37 (minimum = 0.13, maximum = 0.77, SD = 0.17. IRIS is a low-cost, easy to manage, highly sensitive and specific test for H. pylori detection. Storing and mailing the samples did not interfere with the performance of the test.

  18. Utilization of urea micro dose with {sup 14} C in breath test to detect the Helicobacter pylori; Utilizacao de micro dose de ureia com {sup 14} C no teste respiratorio para diagnosticar a presenca de Helicobacter pylori

    Energy Technology Data Exchange (ETDEWEB)

    Chausson, Yvon [Centro de Desenvolvimento da Tecnologia Nuclear (CDTN), Belo Horizonte, MG (Brazil); Coelho, Luiz Gonzaga V.; Passos, Maria do Carmo F.; Andrade, Angela A.M.; Simal, Carlos J.R.; Paula Castro, Luiz de [Minas Gerais Univ., Belo Horizonte, MG (Brazil). Hospital das Clinicas; Fernandes, M.L.; Yazaki, F.R. [Minas Gerais Univ., Belo Horizonte, MG (Brazil). Dept. de Estatistica

    1995-12-31

    A lower dose is used in the {sup 14} C-urea breath test to detect the Helicobacter pylori (Hp). Such dose produce trivial radiation doses. The results shown that the use of this desirable dose is possible. (author). 4 refs., 1 fig.

  19. Prevalence of Helicobacter Pylori Infection in School and Pre-School Aged Children with C-14 Urea Breath Test and the Association with Familial and Environmental Factors

    Directory of Open Access Journals (Sweden)

    Alev Çınar

    2015-06-01

    Full Text Available Objective: To investigate the prevalence of Helicobacter pylori (Hp infection in pre-school and school age children with C-14 urea breath test, and to explore its association with age and socioeconomic factors in Turkey. Methods: Hp infection status was determined by using Urea Breath Test (UBT. Patients who had previous gastric surgery, Hp eradication treatment or equivocal UBT results were excluded. A questionnaire was administered to elicit information on gender, age, ABO/Rh blood group type, presence of gastric disease in the family, domestic animal in the household, and treatment for idiopathic Iron Deficiency Anemia (IDA. Results: This retrospective study included 500 pediatric patients (179 boys, 321 girls, mean age 10.7±4.3 years of whom 62 (12.4% were aged ≤6 years and 438 (87.6% were aged 7 to 16 years. Helicobacter pylori (Hp was positive in 245 (49% cases. In the pre-school age group, 21/62 cases (34% had positive UBT while in the school age group 224/438 children (51% had positive UBT. A family history of dyspepsia and pet ownership were not associated with Hp positivity. Hp positive 76 (29.8% children were on IDA treatment but this was not statistically significant. Conclusion: The Hp infection positivity rate was 49% in the pediatric age study group. The positivity rate was significantly lower at preschool age than school age, and it increased with age. There was no association with gender, ABO/Rh blood groups, presence of domestic pets, IDA, or history of gastric disease in the family.

  20. Urease-positive bacteria in the stomach induce a false-positive reaction in a urea breath test for diagnosis of Helicobacter pylori infection.

    Science.gov (United States)

    Osaki, Takako; Mabe, Katsuhiro; Hanawa, Tomoko; Kamiya, Shigeru

    2008-07-01

    This study investigated the influence of urease-positive non-Helicobacter pylori bacteria on the results of a urea breath test (UBT) to evaluate the diagnostic utility of a UBT using film-coated [(13)C]urea tablets. The UBT was performed in 102 patients treated with a proton pump inhibitor and antibiotics for the eradication of H. pylori. Urease-producing bacteria other than H. pylori were isolated and identified from the oral cavity and stomach. In 4/102 patients, the UBT gave false-positive results. These false-positive results were found to be caused by the presence of urease-positive bacteria in the oral cavity and stomach. Five bacterial species with urease activity (Proteus mirabilis, Citrobacter freundii, Klebsiella pneumoniae, Enterobacter cloacae and Staphylococcus aureus) were subsequently isolated from the oral cavity and/or stomach. As there was no correlation between the in vitro urease activity of urease-positive non-H. pylori bacteria and the UBT value, and all of the patients with a false-positive UBT result were suffering from atrophic gastritis, it is possible that the false-positive results in the UBT were a result of colonization of urease-positive bacteria and gastric hypochlorhydric conditions. Thus, for the diagnosis of H. pylori infection using a UBT, the influence of stomach bacteria must be considered when interpreting the results.

  1. A methodological aspect of the {sup 14}C-urea breath test used in Helicobacter pylori diagnosis; Wybrany aspekt metodologiczny testu oddechowego z mocznikiem znakowanym stosowanego w diagnostyce zakazenia Helicobacter pylori

    Energy Technology Data Exchange (ETDEWEB)

    Kopanski, Z.; Niziol, J.; Micherdzinski, J.; Wasilewska-Radwanska, M.; Cienciala, A.; Lasa, J.; Witkowska, B. [Szpital Wojskowy, Cracow (Poland)]|[Institute of Physics and Nuclear Techniques, Academy of Mining and Metallurgy, Cracow (Poland)]|[Institute of Nuclear Physics, Cracow (Poland)

    1996-12-31

    The main purpose of those investigations was optimisation of the performing time of the breath test with {sup 14}C-labelled urea which reveals Helicobacter pylori infection. It was analysed 117 species, preselected according to endoscopy and histopathology results, 56 of them have suffered from chronic gastritis and 61 from gastric ulcer disease. Using microbiology diagnosis (culture + IFP test) it was found that 86 species were H. pylori infected. This group of patients were next subject to investigations with the breath test with {sup 14}C-labelled urea. Measurements of radioactivity of breathe air have been carried out for 30 minutes. The obtained results allow us to maintain that the optimal time of duration of the test described above is 30 minutes. (author) 38 refs, 2 tabs, 1 fig

  2. Comparison of three stool antigen assays with the 13C- urea breath test for the primary diagnosis of Helicobacter pylori infection and monitoring treatment outcome.

    LENUS (Irish Health Repository)

    Hooton, Carmel

    2012-02-03

    BACKGROUND: The urea breath test (UBT) is the gold-standard non-invasive test for the detection of Helicobacter pylori infection, however, the lack of availability of the UBT due to the high cost of the test, and in particular the need for expensive analytical instrumentation, limits the usefulness of this method. Stool antigen assays may offer an alternative non-invasive method for the diagnosis of infection. OBJECTIVE: To compare the accuracy of three stool antigen assays (HpSA, IDEIA HpStAR, and ImmunoCard STAT) against the UBT for the primary diagnosis of H. pylori infection and for monitoring treatment outcome. METHODS: A total of 102 patients attending two gastroenterology day-case clinics for the investigation of dyspepsia were included. Each patient provided breath and stool samples for analysis. Patients who tested positive for H. pylori by the validated UBT were prescribed triple therapy and invited to return for repeat breath and stool sample analysis 6 weeks post-treatment. RESULTS: Of the 102 patients tested, 48 were diagnosed with H. pylori infection by the UBT. The HpSA assay interpreted 38 of these as positive (79% sensitive). Of the 54 UBT-negative patients the HpSA assay interpreted all 54 as negative (100% specific). The IDEIA HpStAR assay correctly identified 44 patients as positive (92% sensitive) and 50 as negative (92.5% specific). The ImmunoCard STAT assay interpreted 38 patients as positive (79% sensitive) and 52 as negative (96.3% specific). CONCLUSION: The findings indicate that the IDEIA HpStAR stool antigen kit is the most accurate assay of the three assays evaluated, and possibly represents a viable alternative to the UBT for the primary diagnosis of H. pylori infection and for monitoring treatment outcome.

  3. Comparison of a monoclonal antigen stool test (Hp StAR) with the 13C-urea breath test in monitoring Helicobacter pylori eradication therapy

    Institute of Scientific and Technical Information of China (English)

    Francesco Perri; Michele Quitadamo; Rosalba Ricciardi; Ada Piepoli; Rosa Cotugno; Annamaria Gentile; Alberto Pilotto; Angelo Andriulli

    2005-01-01

    AIM: To evaluate the agreement between a mAb-based stool test (HP StAR) and the urea breath test (UBT) in monitoring (H pylori) infection after eradication therapy.METHODS: Patients with discordant results on UBT and Hp StAR underwent endoscopy with biopsies for rapid urease test, culture, and histology to confirm H pylori status.RESULTS: Among 250 patients (50±14 years), 240 (96.0%) had concordant UBT and Hp StAR tests with a significant correlation between DOB and A values (R = 0.87; P<0.0001).The remaining 10 (4.0%) patients had discordant tests (positive Hp StAR and negative UBT) with the Hp StAR inaccurate in five cases (false positive) and UBT inaccurate in the other five cases (false negative). The "maximal expected" sensitivity, specificity, +PV, -PV, +LR, and -LR were 91%, 100%, 100%, 97.4%, ∞, and 8.2 respectively,for the UBT, and 100%, 97.4%, 91%, 100%, 38.8, and 0,respectively, for the Hp StAR. Overall accuracy for both tests was 98%.CONCLUSION: Both the UBT and the Hp StAR are equally accurate in monitoring H pylori infection. Nowadays,the choice of the "best" non-invasive H pylori test in the post-treatment setting should be done not only in terms of diagnostic accuracy but also in view of cost and local facilities.

  4. Cost effectiveness analysis of population-based serology screening and 13C-Urea breath test for Helicobacter pylori to prevent gastric cancer: A markov model

    Institute of Scientific and Technical Information of China (English)

    Feng Xie; Nan Luo; Hin-Peng Lee

    2008-01-01

    AIM: To compare the costs and effectiveness of no screening and no eradication therapy, the populationbased Hdlicobacter pylori (H pylori) serology screening with eradication therapy and 13C-Urea breath test (UBT)with eradication therapy.METHODS: A tarkov model simulation was carried out in all 237900 Chinese males with age between 35 and 44 from the perspective of the public healthcare provider in Singapore. The main outcome measures were the costs, number of gastric cancer cases prevented, life years saved, and quality-adjusted life years (QALYs)gained from screening age to death. The uncertainty surrounding the cost-effectiveness ratio was addressed by one-way sensitivity analyses.RESULTS: Compared to no screening, the incremental cost-effectiveness ratio (ICER) was $16166 per life year saved or $13571 per QALY gained for the serology screening, and $38792 per life year saved and $32525 per QALY gained for the UBT. The ICER was $477079 per life year saved or $390337 per QALY gained for the UBT compared to the serology screening. The costeffectiveness of serology screening over the UBT was robust to most parameters in the model.CONCLUSION: The population-based serology screening for H pylori was more cost-effective than the UBT in prevention of gastric cancer in Singapore Chinese males.

  5. Pre-treatment urea breath test results predict the efficacy of Helicobacter pylori eradication therapy in patients with active duodenal ulcers

    Institute of Scientific and Technical Information of China (English)

    Yung-Chih Lai; Jyh-Chin Yang; Shih-Hung Huang

    2004-01-01

    AIM: To evaluate the association of pre-treatment 13C-urea breath test (UBT) results with H pyloridensity and efficacy of eradication therapy in patients with active duodenal ulcers.METHODS: One hundred and seventeen consecutive outpatients with active duodenal ulcer and H pyloriinfection were recruited. H pylori density was histologically graded according to the Sydney system. Each patient received lansoprazole (30 mg b.i.d.), clarithromycin (500 mg b.i.d.) and amoxicillin (1 g b.i.d.) for 1 week. According to pre-treatment UBT values, patients were allocated into low (<16%o),intermediate (16-35%o), and high (>35%o) UBT groups.RESULTS: A significant correlation was found between pre-treatment UBT results andHpyloridensity (P<0.001).H pylorieradication rates were 94.9%, 94.4% and 81.6%in the low, intermediate and high UBT groups, respectively (per protocol analysis, P=0.11). When patients were assigned into two groups (UBT results ≤35%o and >35%o),the eradication rates were 94.7% and 81.6%, respectively (P=0.04).CONCLUSION: The intragastric bacterial load of H pylori can be evaluated by UBT, and high pre-treatment UBT results can predict an adverse outcome of eradication therapy.

  6. Validation of the string test for the recovery of Helicobacter pylori from gastric secretions and correlation of its results with urea breath test results, serology, and gastric pH levels.

    Science.gov (United States)

    Torres, J; Camorlinga, M; Pérez-Peréz, G; Gonzalez, G; Muñoz, O

    2001-04-01

    The efficacy of the string culture test to isolate Helicobacter pylori from gastric secretions of 28 volunteers was studied. With the urea breath test (UBT) as the "gold standard," the string culture test showed a sensitivity of 75% and a specificity of 100%. The results of string culture did not correlate with the UBT results, with serum antibody levels, or with the pH levels of gastric secretions.

  7. MIN {sup 14}C UBT: A combination of gastric basal transit and {sup 14}C-urea breath test for the detection of helicobacter pylori infection in human beings

    Energy Technology Data Exchange (ETDEWEB)

    Zubillaga, M.; Oliveri, P.; Calcagno, M.L.; Goldman, C.; Caro, R.; Mitta, A.; Degrossi, O.; Boccio, J

    1997-08-01

    The purpose of this work is to demonstrate that the {sup 14}C-urea breath test (UBT) performed at different times combined with the study of the gastric basal transit, which evaluates the intragastric displacement of a labeled solution under fasting conditions, has the advantage of being representative of the whole stomach surface and constitutes a non-aggressive test for the detection of H. pylori. This test, which has been called MIN {sup 14}C UBT, is a modification of the conventional {sup 14}C UBT in which low volumes of a solution of {sup 14}C-urea together with {sup 99m}Tc-sulfur colloid are administered. The {sup 99m}Tc-sulfur colloid is not absorbed in the gastrointestinal tract and has the great advantage of allowing the 'visualization' of the transit of the {sup 14}C-urea within the gastrointestinal tract. This modification allows the simultaneous determination of the production of the {sup 14}CO{sub 2} and the place where this process occurs. The results show that there is a good correlation between the images obtained and the breath samples collected. We found that this test has a sensitivity of 98% and a specificity of 96% for H. pylori detection.

  8. Biokinetics and radiation dosimetry of {sup 14}C-labelled triolein, urea, glycocholic acid and xylose in man. Studies related to nuclear medicine 'breath tests' using accelerator mass spectrometry

    Energy Technology Data Exchange (ETDEWEB)

    Gunnarsson, Mikael

    2002-08-01

    {sup 14}C-labelled substances have been used in biomedical research and clinical medicine for over 50 years. Physicians and scientists however, often hesitate to use these substances in patients and volunteers because the radiation dosimetry is unclear. In this work detailed long-term biokinetic and dosimetric estimation have been carried out for four clinically used {sup 14}C-breath tests: {sup 14}C-triolein (examination of fat malabsorption), urea (detection of Helicobacter pylori infection in the stomach), glycocholic acid and xylose (examination of bacterial overgrowth in the small intestine) by using the highly sensitive accelerator mass-spectrometry (AMS) technique. The AMS technique has been used to measure low {sup 14}C concentrations in small samples of exhaled air, urine, faeces and tissue samples and has improved the base for the estimation of the absorbed dose to various organs and tissues and the effective dose to man. The high sensitivity of the AMS system has also made it possible to perform {sup 14}C breath tests on patient groups which were earlier subject for restriction (e.g. small children). In summary, our results show that for adult patients - and in the case of {sup 14}C-urea breath test also for children down to 3 years of age - the dose contributions are comparatively low, both described as organ doses and as effective doses. For adults, the latter is: {sup 14}C-glycocholic acid - 0.4 mSv/MBq, {sup 14}C-triolein - 0.3 mSv/MBq, {sup 14}C-xylose - 0.1 mSv/MBq and {sup 14}C-urea - 0.04 mSv/MBq. Thus, from a radiation protection point of view there is no reason for restrictions in using any of the {sup 14}C-labelled radiopharmaceutical included in this work in the activities normally used (0.07-0.2 MBq for a 70 kg patient)

  9. Carbon-14 Bomb-Pulse Dating

    Energy Technology Data Exchange (ETDEWEB)

    Buchholz, B A

    2007-12-16

    Atmospheric testing of nuclear weapons during the 1950s and early 1960s doubled the concentration of carbon-14 atmosphere and created a pulse that labeled everything alive in the past 50 years as carbon moved up the food chain. The variation in carbon-14 concentration in time is well-documented and can be used to chronologically date all biological materials since the mid-1950s.

  10. The interest of the {sup 13}C urea breath test for the diagnostic and monitoring of chronic duodenal ulcer; Interet du test respiratoire a l`uree {sup 13}C dans le diagnostic et le suivi de l`ulcere duodenal chronique

    Energy Technology Data Exchange (ETDEWEB)

    Rousseau-Tsangaris, M. [INBIOMED, 69 - Lyon (France); Centarti, M.; Mion, F.; Minaire, Y. [Hopital Edouard-Herriot, 69 - Lyon (France); Brazier, J.L. [Faculte de Pharmacie, 69 - Lyon (France)

    1994-12-31

    Duodenal ulcer is very frequently associated with Helicobacter pylori (Hp) present in the gastric mucous membrane. Breath tests with {sup 13}C-labelled urea have been carried out for the detection of Hp; these tests could be more sensitive than gastric biopsies, because of the heterogenous distribution of the bacteria in the mucous membrane. This breath test may be used repetitively and allows for a non-intrusive monitoring of the Hp eradication after treatment. 12 refs.

  11. Validación de método simplificado de la prueba en aliento con urea-13C para diagnóstico de infección por Helicobacter pylori Validation of a simplified method of the 13C urea breath test for diagnosis of Helicobacter pylori

    Directory of Open Access Journals (Sweden)

    N. X. Ortiz-Olvera Nayeli

    2007-07-01

    Full Text Available Objetivo: validar un método simplificado de la prueba en aliento con urea-13C (PAU-13Cs para el diagnóstico de infección por Helicobacter pylori (H. pylori, con administración simultánea de 50 mg de urea-13C y 2 g de ácido cítrico. Material y métodos: se estudiaron 88 pacientes (49 mujeres y 39 hombres; con promedio de edad 45 ± 15 años, referidos para endoscopia gastrointestinal y toma de biopsias. La PAU-13Cs se realizó en ayuno. Se recolectaron las muestras de aire espirado en tubos de cristal de 10 ml, antes y 30 minutos después de administrar simultáneamente 50 mg de urea-13C y 2 g de ácido cítrico disueltos en 200 ml de agua. Las muestras se analizaron por espectrometría de masas. El diagnóstico de infección se consideró cuando el cultivo y/o la biopsia y serología fueron positivas para H. pylori. Resultados: cincuenta y un pacientes (57,95% fueron positivos, 30 (34,10% negativos para H. pylori y 7 (7,95% casos se consideraron indeterminados. La sensibilidad, especificidad, valor predictivo positivo y negativo de PAU-13Cs fue de 90,2, 93,3, 95,8 y 84,8%, respectivamente. Con exactitud de 91,4%. Conclusión: la administración simultánea de 50 mg de urea-13C y 2 g de ácido cítrico, representa una alternativa para el diagnóstico no invasivo de infección por H. pylori, debido a que conserva la certeza diagnóstica de la PAU-13C.Objective: to validate a simplified 13C-urea breath test (13C-UBT method for the diagnosis of H. pylori infection. Material and methods: patients referred for gastrointestinal endoscopy and biopsy were included, and a 13C-UBT was performed after a 6-hour fast. Breath samples were collected in 10 ml glass tubes before and 30 min after the simultaneous administration of 50 mg of 13C-urea and 2 g of citric acid in 200 ml of water. All breath samples were analyzed using isotope ratio mass spectrometry. The diagnosis of H. pylori infection was established with a positive culture and/or positive

  12. Synthesis of carbon-14 labeled vigabatrin. [Antieplileptic

    Energy Technology Data Exchange (ETDEWEB)

    Schuster, A.J.; Wagner, E.R. (Marion Merrell Dow Inc, Indianapolis, IN (United States))

    1993-01-01

    Carbon-14 labeled vigabatrin was synthesized in 5 steps from 5-hydroxymethyl-2-pyrrolidone tosylate and NaCN-[[sup 14]C]. A key step involved reduction of the resulting nitrile in the presence of excess dimethylamine to give the dimethylamino-ethyl 2-pyrrolidone derivative in one step. This afforded an overall radiochemical yield of 22% and radiochemical purity greater than 98%. (Author).

  13. Synthesis of carbon-14 labeled doxylamine succinate

    Energy Technology Data Exchange (ETDEWEB)

    Rao, P.N.; Damodaran, K.M.

    1986-05-01

    Doxylamine succinate, N,N-dimethyl-2-(1-phenyl-1-(2-pyridinyl)-ethoxy)ethanamine succinate is an antihistamine used primarily as a sedative. Carbon-14 labeled doxylamine succinate, required for toxicological studies, was synthesized in two steps starting from 2-benzoyl pyridine.

  14. Diagnosis of Helicobacter pylori infection; Culture, microscopy of biopsy smears, and the rapid urease test compared with the sup 14 C-urea breath test. Diagnostikk av Helicobacter pylori-infeksjon; Urease hurtigtest, mikroskopi av utstryk, og dyrking av ventrikkelbiopsi sammenlignet med sup 14 C-urea-pusteproeven

    Energy Technology Data Exchange (ETDEWEB)

    Nysaeter, G.; Berstad, K.; Weberg, R.; Berstad, A.; Hardardottir, H. (Haukeland Hospital, Bergen (Norway))

    1992-08-01

    By employing the {sup 14}C-urea breath test as the reference methods the authors determined the specificity and sensitivity of three bioptic methods for diagnosis of Helicobacter pylori infection in 103 subjects. All biopsy specimens were obtained from the gastric antrum. For culture the specificity was 100%. Its applicability was reduced, however, by a low sensitivity (73.8%) and a delay of several days before the final result was available. Microscopy of Loeffler-stained biopsy smears yielded a specificity of 100% and a sensitivity of 92.9%, but the method was regarded time-consuming. The rapid urease test yielded a specificity of 98.4% and a sensitivity of 85.7%. Being quick, simple and inexpensive, the rapid urease test is well suited for routine use in gastroscopy. 17 refs., 4 tabs.

  15. The carbon 14 and environment; Le carbone 14 et l'environnement

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    2007-07-01

    This article resume the history and the properties of the carbon 14 ({sup 14}C). We also find the different origins and the produced quantities. The carbon transfers in environment are explained and so the {sup 14}C. The biological effects and the sanitary aspects are clarified. The measurements of carbon 14 are given as well its application through the dating. The waste management is tackled. (N.C.)

  16. LDEO Carbon 14 Data from Selected Sea floor Cores

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Carbon-14 data in this file were compiled by W.F. Ruddiman and staff at the Lamont-Doherty Earth Observatory of Columbia University. Data include 974 carbon-14 dates...

  17. VALIDATION OF 14C-UREA BREATH TEST FOR DIAGNOSIS OF Helicobacter pylori Validação do teste expiratório com 14C-uréia para o diagnóstico do Helicobacter pylori

    Directory of Open Access Journals (Sweden)

    Rejane MATTAR

    1999-01-01

    Full Text Available The aim of this study was to validate the 14C-urea breath test for use in diagnosis of Helicobacter pylori infection. Thirty H. pylori positive patients, based on histologic test and thirty H. pylori negative patients by histology and anti-H. pylori IgG entered the study. Fasting patients drank 5 uCi of 14C-urea in 20 ml of water. Breath samples were collected at 0, 5, 10, 15, 20 and 30 min. The difference of cpm values between the two groups was significant at all the time intervals, besides time 0 (pO teste expiratório com 14C-uréia diagnostica infecção pelo Helicobacter pylori no estômago. A urease, produzida por esta bactéria, quebra a 14C-uréia, resultando em HCO3- e NH4+, sendo expirado 14CO2 pelos pulmões e quantificado, então, por contador Beta. O objetivo do nosso estudo foi validar o teste expiratório com 14C-uréia, determinando o tempo ideal de coleta da amostra e o valor de corte. Foi definido o tempo de 20 min para coleta do exame após a ingestão de 5 uCi de 14C-uréia com valor de corte de 562 cpm. A sensibilidade e a especificidade do teste foram de 100% aos 20 min. As diferenças de contagens entre os grupos Helicobacter pylori negativos e Helicobacter pylori positivos foram estatisticamente significativas (p<0,0001. As pacientes do sexo feminino, aos 20 min apresentaram contagens superiores às dos pacientes do sexo masculino (p=0,005. É preciso verificar se as mulheres têm maior densidade bacteriana, ou se é pelo fato dos homens expirarem mais CO2, diluindo a amostra. O teste expiratório com 14C-uréia é método diagnóstico não invasivo, muito sensível, específico e barato.

  18. 口臭患者14C呼气试验检测的结果分析%Analysis of 14C-Urea Breath Test in Patients with Halitosis

    Institute of Scientific and Technical Information of China (English)

    陈建中; 张旭峰; 张斌; 李黎; 童妙春; 陈驰

    2012-01-01

    Objective To explore the relationship between halitosis and the infection of helicobacter pylori (HP). Methods The results of l4C-urea breath test of 59 normal people, 50 patients with halitosis only and 56 patients infected by both halitosis and digestive diseases were analyzed. Results It showed that the 14C content and HP positive rate in group infected by both halitosis and digestive diseases were much higher than that of halitosis only group and normal people group (P <0.05). Conclusion The infection of Helicobacter pylori is an important factor but not only factor of halitosis.%目的 探讨口臭与幽门螺旋杆菌及其它因素的关系.方法 对59名正常组、50例单纯口臭组患者、56例口臭伴消化道疾病组患者14C 呼气试验的结果进行分析.结果 分析结果表明,口臭伴消化道疾病组14C呼气试验含量明显高于单纯口臭组和正常组(P<0.05),阳性率也明显高于单纯口臭组和正常组(P<0.05).结论 幽门螺旋杆菌感染是口臭的重要原因,但不是唯一原因.

  19. The lichens, tritium and carbon 14 integrators; Les lichens, integrateurs de tritium et de carbone 14

    Energy Technology Data Exchange (ETDEWEB)

    Daillant, O

    2007-07-01

    The present report concerns a research for the tritium and for the carbon 14 in lichens in a spirit of bio-indication: the first results appear in Daillant and al (2004 ) and additional results were presented to the congress B.I.O.M.A.P. in Slovenia, organized collectively by the institute Josef Stefan from Ljubljana and the international atomic energy agency from Vienna (Daillant and al 2003). (N.C.)

  20. Removal of carbon-14 from irradiated graphite

    Science.gov (United States)

    Dunzik-Gougar, Mary Lou; Smith, Tara E.

    2014-08-01

    Approximately 250,000 tonnes of irradiated graphite waste exists worldwide and that quantity is expected to increase with decommissioning of Generation II reactors and deployment of Generation IV gas-cooled, graphite moderated reactors. This situation indicates the need for a graphite waste management strategy. On of the isotopes of great concern for long-term disposal of irradiated graphite is carbon-14 (14C), with a half-life of 5730 years. Study of irradiated graphite from some nuclear reactors indicates 14C is concentrated on the outer 5 mm of the graphite structure. The aim of the research presented here is to develop a practical method by which 14C can be removed. In parallel with these efforts, the same irradiated graphite material is being characterized to identify the chemical form of 14C in irradiated graphite. A nuclear-grade graphite, NBG-18, and a high-surface-area graphite foam, POCOFoam®, were exposed to liquid nitrogen (to increase the quantity of 14C precursor) and neutron-irradiated (1013 neutrons/cm2/s). During post-irradiation thermal treatment, graphite samples were heated in the presence of an inert carrier gas (with or without the addition of an oxidant gas), which carries off gaseous products released during treatment. Graphite gasification occurs via interaction with adsorbed oxygen complexes. Experiments in argon only were performed at 900 °C and 1400 °C to evaluate the selective removal of 14C. Thermal treatment also was performed with the addition of 3 and 5 vol% oxygen at temperatures 700 °C and 1400 °C. Thermal treatment experiments were evaluated for the effective selective removal of 14C. Lower temperatures and oxygen levels correlated to more efficient 14C removal.

  1. Breathing Problems

    Science.gov (United States)

    ... getting enough air. Sometimes you can have mild breathing problems because of a stuffy nose or intense ... panic attacks Allergies If you often have trouble breathing, it is important to find out the cause.

  2. Quantifying Carbon-14 for Biology Using Cavity Ring-Down Spectroscopy

    OpenAIRE

    McCartt, A. Daniel; Ognibene, Ted J.; Bench, Graham; Turteltaub, Kenneth W.

    2016-01-01

    A cavity ring-down spectroscopy (CRDS) instrument was developed using mature, robust hardware for the measurement of carbon-14 in biological studies. The system was characterized using carbon-14 elevated glucose samples and returned a linear response up to 387 times contemporary carbon-14 concentrations. Carbon-14 free and contemporary carbon-14 samples with varying carbon-13 concentrations were used to assess the method detection limit of approximately one-third contemporary carbon-14 levels...

  3. National Low-Level Waste Management Program Radionuclide Report Series. Volume 3, Carbon-14

    Energy Technology Data Exchange (ETDEWEB)

    Rudin, M.J.; Garcia, R.S.

    1992-02-01

    This report, Volume 3 of the National Low-Level Radioactive Waste Management Program Radionuclide Report Series, discusses the radiological and chemical characteristics of carbon-14. The report also discusses waste streams that contain carbon-14, waste forms that contain carbon-14, and carbon-14 behavior in the environment and in the human body.

  4. Carbon-14 background, pathway, and dose optimization analysis

    Energy Technology Data Exchange (ETDEWEB)

    Caffrey, E.; Higley, K. [Oregon State University (United States)

    2014-07-01

    Carbon-14 is radiologically relevant due to its long half-life coupled with its ease of incorporation into the global carbon cycle. The majority of carbon-14 releases from nuclear power plants in the United States are gaseous, and terrestrial samples constitute the primary indicator of increased environmental levels, and thus represent an important pathway for the incorporation of the radionuclide into both human and nonhuman populations. This project was broken into three phases: In phase one, information was summarized on background quantities and production mechanisms of carbon-14 in the general environment and adjacent to nuclear power plants. The second phase involved the review and analysis of nuclear power plant carbon-14 pathways to humans as compared to the United States Nuclear Regulatory Commission's Regulatory Guide 1.109 methodologies (based on ICRP 2), and identified areas where dose calculations could be optimized. Alternative models for calculating plant uptake from atmosphere and transfer in the food chain were investigated, with particular emphasis on models used by countries in the European Union. In phase three, collard green samples grown at three different locations relative to a nuclear power plant (one control garden and two downwind gardens) were evaluated using a Perkin Elmer TriCarb 3180 TR/SL Liquid Scintillation Counter (LSC). Samples were first oven dried and combusted using a Perkin Elmer Model 307 Oxidizer, and activity concentrations were calculated based on the LSC count data. These data were compared to samples analyzed using accelerator mass spectrometry. There was no statistically significant difference in carbon-14 concentrations at the two downwind gardens as compared to the control garden. This research is based on work supported, in part, by the Electrical Power Research Institute (EPRI). The opinions, findings, conclusions, or recommendations expressed herein are those of the author(s) and do not necessarily represent

  5. Quantifying Carbon-14 for Biology Using Cavity Ring-Down Spectroscopy.

    Science.gov (United States)

    McCartt, A Daniel; Ognibene, Ted J; Bench, Graham; Turteltaub, Kenneth W

    2016-09-06

    A cavity ring-down spectroscopy (CRDS) instrument was developed using mature, robust hardware for the measurement of carbon-14 in biological studies. The system was characterized using carbon-14 elevated glucose samples and returned a linear response up to 387 times contemporary carbon-14 concentrations. Carbon-14 free and contemporary carbon-14 samples with varying carbon-13 concentrations were used to assess the method detection limit of approximately one-third contemporary carbon-14 levels. Sources of inaccuracies are presented and discussed, and the capability to measure carbon-14 in biological samples is demonstrated by comparing pharmacokinetics from carbon-14 dosed guinea pigs analyzed by both CRDS and accelerator mass spectrometry. The CRDS approach presented affords easy access to powerful carbon-14 tracer techniques that can characterize complex biochemical systems.

  6. Synthesis of pentamidine labelled with tritium and carbon-14

    Energy Technology Data Exchange (ETDEWEB)

    Hesk, D.; Jones, J.R. (Surrey Univ., Guildford (UK). Dept. of Chemistry); Lockley, W.J.S.; Wilkinson, D.J. (Fisons plc, Loughborough (UK). Pharmaceutical Div.)

    1990-11-01

    Tritium labelled pentamidine has been prepared with a specific activity of 90 mCi mmol{sup -1} using a one-step exchange reaction between the unlabelled drug and tritiated water. The labelling utilised a homogeneous rhodium trichloride catalyst and yielded pentamidine regiospecifically labelled in the positions ortho to the amidine groups. Carbon-14 labelled pentamidine was prepared via a seven-step procedure in which the isotope was introduced via a nucleophilic substitution of 4-bromo-phenol with copper(I) ({sup 14}C)cyanide. (author).

  7. Hereditary urea cycle abnormality

    Science.gov (United States)

    ... vitro so the specific genetic cause is known. Teamwork between parents, the affected child, and doctors can help prevent severe illness. Alternative Names Abnormality of the urea cycle - hereditary; Urea cycle - hereditary abnormality Images Male urinary system Urea cycle References Lichter-Konecki ...

  8. Measurements of carbon-14 with cavity ring-down spectroscopy

    Science.gov (United States)

    McCartt, A. D.; Ognibene, T.; Bench, G.; Turteltaub, K.

    2015-10-01

    Accelerator Mass Spectrometry (AMS) is the most sensitive method for quantitation of 14C in biological samples. This technology has been used in a variety of low dose, human health related studies over the last 20 years when very high sensitivity was needed. AMS helped pioneer these scientific methods, but its expensive facilities and requirements for highly trained technical staff have limited their proliferation. Quantification of 14C by cavity ring-down spectroscopy (CRDS) offers an approach that eliminates many of the shortcomings of an accelerator-based system and would supplement the use of AMS in biomedical research. Our initial prototype, using a non-ideal wavelength laser and under suboptimal experimental conditions, has a 3.5-modern, 1- σ precision for detection of milligram-sized, carbon-14-elevated samples. These results demonstrate proof of principle and provided a starting point for the development of a spectrometer capable of biologically relevant sensitivities.

  9. Breath alcohol test

    Science.gov (United States)

    Alcohol test - breath ... There are various brands of breath alcohol tests. Each one uses a different method to test the level of alcohol in the breath. The machine may be electronic or manual. One ...

  10. Rapid shallow breathing

    Science.gov (United States)

    Tachypnea; Breathing - rapid and shallow; Fast shallow breathing; Respiratory rate - rapid and shallow ... Shallow, rapid breathing has many possible medical causes, including: Asthma Blood clot in an artery in the lung Choking Chronic obstructive ...

  11. Breathing difficulties - first aid

    Science.gov (United States)

    Difficulty breathing - first aid; Dyspnea - first aid; Shortness of breath - first aid ... Breathing difficulty is almost always a medical emergency. An exception is feeling slightly winded from normal activity, ...

  12. Optoacoustic 13C-breath test analyzer

    Science.gov (United States)

    Harde, Hermann; Helmrich, Günther; Wolff, Marcus

    2010-02-01

    The composition and concentration of exhaled volatile gases reflects the physical ability of a patient. Therefore, a breath analysis allows to recognize an infectious disease in an organ or even to identify a tumor. One of the most prominent breath tests is the 13C-urea-breath test, applied to ascertain the presence of the bacterium helicobacter pylori in the stomach wall as an indication of a gastric ulcer. In this contribution we present a new optical analyzer that employs a compact and simple set-up based on photoacoustic spectroscopy. It consists of two identical photoacoustic cells containing two breath samples, one taken before and one after capturing an isotope-marked substrate, where the most common isotope 12C is replaced to a large extent by 13C. The analyzer measures simultaneously the relative CO2 isotopologue concentrations in both samples by exciting the molecules on specially selected absorption lines with a semiconductor laser operating at a wavelength of 2.744 μm. For a reliable diagnosis changes of the 13CO2 concentration of 1% in the exhaled breath have to be detected at a concentration level of this isotope in the breath of about 500 ppm.

  13. Living with urea stress

    Indian Academy of Sciences (India)

    Laishram R Singh; Tanveer Ali Dar; Faizan Ahmad

    2009-06-01

    Intracellular organic osmolytes are present in certain organisms adapted to harsh environments. These osmolytes protect intracellular macromolecules against denaturing environmental stress. In contrast to the usually benign effects of most organic osmolytes, the waste product urea is a well-known perturbant of macromolecules. Although urea is a perturbing solute which inhibits enzyme activity and stability, it is employed by some species as a major osmolyte. The answer to this paradox was believed to be the discovery of protective osmolytes (methylamines). We review the current state of knowledge on the various ways of counteracting the harmful effects of urea in nature and the mechanisms for this. This review ends with the mechanistic idea that cellular salt (KCl/NaCl) plays a crucial role in counteracting the effects of urea, either by inducing required chaperones or methylamines, or by thermodynamic interactions with urea-destabilised proteins. We also propose future opportunities and challenges in the field.

  14. 13C-urea and15N2-urea : Elegant markers to define location and kinetics of in vivo release from a colon-targeted delivery device in men

    NARCIS (Netherlands)

    Schellekens, R.C.A.; Olsder, G.; Maurer, M.; Kosterink, J.; Woerdenbach, H.J.; Wutzke, K.D.; Frijlink, H.W.; Stellaard, F.

    2010-01-01

    Background:13C-urea may be a suitable marker to assess the in vivo fate of colon-targeted dosage forms given by mouth. Release in the colon would lead to fermentation of13C-urea into13CO2and excretion of13CO2in breath, release in the small intestine to detection of13C-urea in blood and urine. The di

  15. Carbon-14 as a tracer of groundwater discharge to streams

    Science.gov (United States)

    Bourke, Sarah; Harrington, Glenn; Cook, Peter; Post, Vincent; Dogramaci, Shawan

    2014-05-01

    The provenance of groundwater discharge to a stream can be determined by measuring the response of multiple groundwater age tracers within the stream across the discharge zone. The sampling interval required to detect groundwater discharge is limited by the rate of equilibration with the atmosphere downstream of the discharge zone, which is determined by the gas transfer velocity. Carbon-14 (14C) equilibration is driven by CO2 exchange, which is a small component of the dissolved inorganic carbon in most stream systems, and therefore the rate of equilibration is slower than for other gaseous age tracers. In this paper we use a step-wise approach to develop and demonstrate the use of 14C as a tracer in streams receiving groundwater discharge. Excess carbon dioxide (CO2) in the emerging groundwater degasses until equilibrium with atmospheric CO2 is reached; increasing pH and enriching the residual 14C by fractionation. In addition, the 14C gradient between groundwater and the atmosphere drives a slower process of isotopic equilibration. We have measured the rates of this chemical and isotopic equilibration experimentally by exposing 250 L of old groundwater to the atmosphere in an evaporation pan. Chemical equilibrium was achieved within 2 days, during which the 14C increased from 6 to 16 pMC. The influence of fractionation during the initial CO2 degassing on isotopic equilibrium rates was negligible. Isotopic equilibrium took over 2 months, with 14C in the evaporation pan increasing to 108 pMC over 71 days. This increase in 14C was simulated using a mass balance model with an effective 14C gas transfer velocity of 0.013 m d-1. Field testing of the method was conducted at two sites. Firstly, we measured the evolution of 14C in dewatering discharge as it flows along an ephemeral creek channel in the Pilbara, Western Australia. Measured 14C increased from 11 to 31 pMC along the 10km reach, which corresponds to a travel time of about 2 days. The measured increase was

  16. How renal cells handle urea.

    Science.gov (United States)

    Bagnasco, S M

    2000-01-01

    The urine concentration process requires an osmolality gradient along the renal cortico-medullary axis, with highest values in the renal papilla. NaCl and urea are the major solutes in the renal inner medulla, concentrations of urea up to 500-600 mM are found in the rat renal papilla. Urea can diffuse across cell membranes and contributes to balance intracellular and extracellular osmotic equilibrium. However, urea has perturbing effects on enzyme activity, and in concentrations above 300 mM is toxic for renal cultured cells. There is increasing evidence that urea can induce cellular responses distinct from those due to NaCl and other non-permeable solutes, including upregulation of immediate-early genes (IEGs). Urea transport by epithelial and endothelial cells is important for intra-medullary urea recycling and preservation of high urea concentration in the inner medulla. Trans-cellular movement of urea in cells expressing urea transporters may influence intracellular levels of this solute and modulate urea-induced signaling pathways. Regulation of urea transporters expression and activity can therefore be viewed as one aspect of cellular adaptation to urea. We have identified tonicity-responsive transcription as one mechanism regulating expression of the urea transporter UT-A. The short-term and long-term effects of variable extracellular urea concentration on the function of renal cells remain still unclear.

  17. What Causes Bad Breath?

    Science.gov (United States)

    ... A Week of Healthy Breakfasts Shyness What Causes Bad Breath? KidsHealth > For Teens > What Causes Bad Breath? A A A en español ¿Qué es lo que provoca el mal aliento? Bad breath, or halitosis , can be a major problem, ...

  18. Ethylated Urea - Ether - Modified Urea - Formaldehyde Resins,

    Directory of Open Access Journals (Sweden)

    Mathew Obichukwu EDOGA

    2006-07-01

    Full Text Available First, phenol - formaldehyde (PF and urea - formaldehyde (UFII resins were separately conventionally prepared in our laboratory. Also, UF resin synthesized from the acid modified synthesis procedure was synthesized in a purely acid medium of pH 1.0, FU molar ratio of 1.0 and at 50oC (one-stage acid modified-synthesis procedure. Subsequently, the UF resin II was modified during synthesis by incorporating ethylated urea-ether (EUER (i.e. UFIII and glycerol (GLYC (i.e. UFV cured with and without acid curing agent. The structural and physicochemical analyses of the various resin samples were carried out.The results showed that the unmodified UF resin (UF II synthesized in acid medium of pH 1.0, F/U molar ratio 1.0, and at 50oC, cured in absence of acid curing catalyst, showed features in their spectra which are consistent with a tri-, and/or tetra-substituted urea in the reaction to give a 3 - dimensional network cured UF resin. Modification of the UF resin(UF II with ethylated urea-ether and glycerol to produce UF resins III and respectively V prominently increased the absorbance of methylene and ether groups in the spectra which are consistent with increased hydrophobicity and improved hydrolytic stability. For the conventional UF resin (UF I, the only clear distinction between spectra for the UF resin II and UF resins (III/V is the presence of diminished peaks for methylene groups at 2.2 ppm. The relationship between the logarithmic viscosity of cured PF resin with time showed continuos dependence of viscosity with time during cure up to 70 minutes. Similar trends were shown by UF resins (III/V, cured in absence of acid catalyst. In contrast, the conventional UF resins I and UF IV (i.e. UF II cured with NH4CL showed abrupt discontinuity in viscosity with time just after about 20 minutes of cure.

  19. Molecular evolution of urea amidolyase and urea carboxylase in fungi

    Directory of Open Access Journals (Sweden)

    Harris Steven D

    2011-03-01

    Full Text Available Abstract Background Urea amidolyase breaks down urea into ammonia and carbon dioxide in a two-step process, while another enzyme, urease, does this in a one step-process. Urea amidolyase has been found only in some fungal species among eukaryotes. It contains two major domains: the amidase and urea carboxylase domains. A shorter form of urea amidolyase is known as urea carboxylase and has no amidase domain. Eukaryotic urea carboxylase has been found only in several fungal species and green algae. In order to elucidate the evolutionary origin of urea amidolyase and urea carboxylase, we studied the distribution of urea amidolyase, urea carboxylase, as well as other proteins including urease, across kingdoms. Results Among the 64 fungal species we examined, only those in two Ascomycota classes (Sordariomycetes and Saccharomycetes had the urea amidolyase sequences. Urea carboxylase was found in many but not all of the species in the phylum Basidiomycota and in the subphylum Pezizomycotina (phylum Ascomycota. It was completely absent from the class Saccharomycetes (phylum Ascomycota; subphylum Saccharomycotina. Four Sordariomycetes species we examined had both the urea carboxylase and the urea amidolyase sequences. Phylogenetic analysis showed that these two enzymes appeared to have gone through independent evolution since their bacterial origin. The amidase domain and the urea carboxylase domain sequences from fungal urea amidolyases clustered strongly together with the amidase and urea carboxylase sequences, respectively, from a small number of beta- and gammaproteobacteria. On the other hand, fungal urea carboxylase proteins clustered together with another copy of urea carboxylases distributed broadly among bacteria. The urease proteins were found in all the fungal species examined except for those of the subphylum Saccharomycotina. Conclusions We conclude that the urea amidolyase genes currently found only in fungi are the results of a horizontal

  20. Electrospray ionization of volatiles in breath

    Science.gov (United States)

    Martínez-Lozano, P.; de La Mora, J. Fernández

    2007-08-01

    Recent work by Zenobi and colleagues [H. Chen, A. Wortmann, W. Zhang, R. Zenobi, Angew. Chem. Int. Ed. 46 (2007) 580] reports that human breath charged by contact with an electrospray (ES) cloud yields many mass peaks of species such as urea, glucose, and other ions, some with molecular weights above 1000 Da. All these species are presumed to be involatile, and to originate from breath aerosols by so-called extractive electrospray ionization EESI [H. Chen, A. Venter, R.G. Cooks, Chem. Commun. (2006) 2042]. However, prior work by Fenn and colleagues [C.M. Whitehouse, F. Levin, C.K. Meng, J.B. Fenn, Proceedings of the 34th ASMS Conference on Mass Spectrometry and Allied Topics, Denver, 1986 p. 507; S. Fuerstenau, P. Kiselev, J.B. Fenn, Proceedings of the 47th ASMS Conference on Mass Spectrometry, 1999, Dallas, TX, 1999] and by Hill and colleagues [C. Wu, W.F. Siems, H.H. Hill Jr., Anal. Chem. 72 (2000) 396] have reported the ability of electrospray drops to ionize a variety of low vapor pressure substances directly from the gas phase, without an apparent need for the vapor to be brought into the charging ES in aerosol form. The Ph.D. Thesis of Martínez-Lozano [P. Martínez-Lozano Sinués, Ph.D. Thesis, Department of Thermal and Fluid Engineering, University Carlos III of Madrid; April 5, 2006 (in Spanish); http://hdl.handle.net/10016/655] had also previously argued that the numerous human breath species observed via a similar ES ionization approach were in fact ionized directly from the vapor. Here, we observe that passage of the breath stream through a submicron filter does not eliminate the majority of the breath vapors seen in the absence of the filter. We conclude that direct vapor charging is the leading mechanism in breath ionization by electrospray drops, though aerosol ionization may also play a role.

  1. Synthesis of carbon-13 and carbon-14 labelled triazolo-1,4-benzodiazepines

    Energy Technology Data Exchange (ETDEWEB)

    Banks, W.R.; Hawi, A.A.; Digenis, G.A. (Kentucky Univ., Lexington, KY (USA). College of Pharmacy)

    1989-04-01

    An efficient two-step synthesis of 8-chloro-1-methyl-6-phenyl-(3H)-S-triazolo-(4,3-a)(1,4)-benzodiazepine (alprazolam) and 8-chloro-6-(2-chlorophenyl)-1-methyl-(3H)-S-triazolo-(4,3-a)(1,4)-benzodiazepine (triazolam) labelled with carbon-13 or carbon-14 from their corresponding hydrazines is reported. The method involved acylation of the appropriate hydrazine using the mixed carbonic anhydride of sodium ({sup 13}C) or ({sup 14}C) acetate and isobutylchloroformate under mild conditions. Thermolysis of the resulting acetylhydrazides gave the target carbon-14 and carbon-13 labelled compounds in good yields. (author).

  2. From breathing to respiration.

    Science.gov (United States)

    Fitting, Jean-William

    2015-01-01

    The purpose of breathing remained an enigma for a long time. The Hippocratic school described breathing patterns but did not associate breathing with the lungs. Empedocles and Plato postulated that breathing was linked to the passage of air through pores of the skin. This was refuted by Aristotle who believed that the role of breathing was to cool the heart. In Alexandria, breakthroughs were accomplished in the anatomy and physiology of the respiratory system. Later, Galen proposed an accurate description of the respiratory muscles and the mechanics of breathing. However, his heart-lung model was hampered by the traditional view of two non-communicating vascular systems - veins and arteries. After a period of stagnation in the Middle Ages, knowledge progressed with the discovery of pulmonary circulation. The comprehension of the purpose of breathing progressed by steps thanks to Boyle and Mayow among others, and culminated with the contribution of Priestley and the discovery of oxygen by Lavoisier. Only then was breathing recognized as fulfilling the purpose of respiration, or gas exchange. A century later, a controversy emerged concerning the active or passive transfer of oxygen from alveoli to the blood. August and Marie Krogh settled the dispute, showing that passive diffusion was sufficient to meet the oxygen needs.

  3. The leachability of carbon-14-labelled 3,4-benzopyrene from coal ash into aqueous systems

    NARCIS (Netherlands)

    Besemer, A.C.; Kanij, J.

    1984-01-01

    The leachability of polycyclic aromatic hydrocarbons from coal ash into aqueous systems was studied. Carbon-14-labeled 3,4-Benzopyrene (BaP) was deposited on coal fly ash by adsorption from the liquid phase in quantities of about 10 ??g/g ash. After a thermal treatment in air at 120??C for 2 hours t

  4. Combustion method for assay of biological materials labeled with carbon-14 or tritium, or double-labeled

    Science.gov (United States)

    Huebner, L. G.; Kisieleski, W. E.

    1969-01-01

    Dry catalytic combustion at high temperatures is used for assaying biological materials labeled carbon-14 and tritium, or double-labeled. A modified oxygen-flask technique is combined with standard vacuum-line techniques and includes convenience of direct in-vial collection of final combustion products, giving quantitative recovery of tritium and carbon-14.

  5. Take a Deep Breath

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    Everyone involved in Beijing’s Olympic Games held their breath last week, not because of the city’s famously polluted air , but in anticipation of the results of an experiment that could help to clean it up.

  6. Minimizing Shortness of Breath

    Science.gov (United States)

    ... is also placed on proper use of the abdominal muscles to better control episodes of shortness of breath, ... Treatment & Programs Health Insights Doctors & Departments Research & Science Education & Training Make a Donation Make an Appointment Contact ...

  7. Breathing difficulty - lying down

    Science.gov (United States)

    ... short of breath. Considerations This is a common complaint in people with some types of heart or ... ADAM Health Solutions. About MedlinePlus Site Map FAQs Customer Support Get email updates Subscribe to RSS Follow ...

  8. Breathing exercises for dysfunctional breathing/hyperventilation syndrome in adults

    OpenAIRE

    2013-01-01

    Copyright © 2013 The Cochrane Collaboration. Published by JohnWiley & Sons, Ltd. Background: Dysfunctional breathing/hyperventilation syndrome (DB/HVS) is a respiratory disorder, psychologically or physiologically based, involving breathing too deeply and/or too rapidly (hyperventilation) or erratic breathing interspersed with breath-holding or sighing (DB). DB/HVS can result in significant patient morbidity and an array of symptoms including breathlessness, chest tightness, dizziness, tre...

  9. National Urea Cycle Disorders Foundation

    Science.gov (United States)

    ... triggers undiagnosed fatal urea cycle disorder in Tennessee wife and teacher. Story . More information about bariatric surgery ... with sodium phenylbutyrate may decrease liver dysfunction in patients with ASA. Details "IN TRIBUTE TO HER SON, ...

  10. The Air We Breathe

    Science.gov (United States)

    Davila, Dina

    2010-01-01

    Topics discussed include NASA mission to pioneer the future in space exploration, scientific discovery and aeronautics research; the role of Earth's atmosphere, atmospheric gases, layers of the Earth's atmosphere, ozone layer, air pollution, effects of air pollution on people, the Greenhouse Effect, and breathing on the International Space Station.

  11. The Breath of Chemistry

    DEFF Research Database (Denmark)

    Josephsen, Jens

    The present preliminary text is a short thematic presentation in biological inorganic chemistry meant to illustrate general and inorganic (especially coordination) chemistry in biochemistry. The emphasis is on molecular models to explain features of the complicated mechanisms essential to breathing...

  12. Breathing Like a Fish

    Science.gov (United States)

    Katsioloudis, Petros J.

    2010-01-01

    Being able to dive and breathe underwater has been a challenge for thousands of years. In 1980, Fuji Systems of Tokyo developed a series of prototype gills for divers as a way of demonstrating just how good its membranes are. Even though gill technology has not yet reached the point where recipients can efficiently use implants to dive underwater,…

  13. Evaporation of urea at atmospheric pressure.

    Science.gov (United States)

    Bernhard, Andreas M; Czekaj, Izabela; Elsener, Martin; Wokaun, Alexander; Kröcher, Oliver

    2011-03-31

    Aqueous urea solution is widely used as reducing agent in the selective catalytic reduction of NO(x) (SCR). Because reports of urea vapor at atmospheric pressure are rare, gaseous urea is usually neglected in computational models used for designing SCR systems. In this study, urea evaporation was investigated under flow reactor conditions, and a Fourier transform infrared (FTIR) spectrum of gaseous urea was recorded at atmospheric pressure for the first time. The spectrum was compared to literature data under vacuum conditions and with theoretical spectra of monomolecular and dimeric urea in the gas phase calculated with the density functional theory (DFT) method. Comparison of the spectra indicates that urea vapor is in the monomolecular form at atmospheric pressure. The measured vapor pressure of urea agrees with the thermodynamic data obtained under vacuum reported in the literature. Our results indicate that considering gaseous urea will improve the computational modeling of urea SCR systems.

  14. Excretory nitrogen metabolism and defence against ammonia toxicity in air-breathing fishes.

    Science.gov (United States)

    Chew, S F; Ip, Y K

    2014-03-01

    With the development of air-breathing capabilities, some fishes can emerge from water, make excursions onto land or even burrow into mud during droughts. Air-breathing fishes have modified gill morphology and morphometry and accessory breathing organs, which would tend to reduce branchial ammonia excretion. As ammonia is toxic, air-breathing fishes, especially amphibious ones, are equipped with various strategies to ameliorate ammonia toxicity during emersion or ammonia exposure. These strategies can be categorized into (1) enhancement of ammonia excretion and reduction of ammonia entry, (2) conversion of ammonia to a less toxic product for accumulation and subsequent excretion, (3) reduction of ammonia production and avoidance of ammonia accumulation and (4) tolerance of ammonia at cellular and tissue levels. Active ammonia excretion, operating in conjunction with lowering of ambient pH and reduction in branchial and cutaneous NH₃ permeability, is theoretically the most effective strategy to maintain low internal ammonia concentrations. NH₃ volatilization involves the alkalization of certain epithelial surfaces and requires mechanisms to prevent NH₃ back flux. Urea synthesis is an energy-intensive process and hence uncommon among air-breathing teleosts. Aestivating African lungfishes detoxify ammonia to urea and the accumulated urea is excreted following arousal. Reduction in ammonia production is achieved in some air-breathing fishes through suppression of amino acid catabolism and proteolysis, or through partial amino acid catabolism leading to alanine formation. Others can slow down ammonia accumulation through increased glutamine synthesis in the liver and muscle. Yet, some others develop high tolerance of ammonia at cellular and tissue levels, including tissues in the brain. In summary, the responses of air-breathing fishes to ameliorate ammonia toxicity are many and varied, determined by the behaviour of the species and the nature of the environment in

  15. Breath Figures Formation

    OpenAIRE

    Guadarrama-Cetina, J.; González-Viñas, W

    2013-01-01

    We present experimental observations of Breath Figures (BF) which are formed by the dew of water when it condenses on a cold surface. The experiments were done in specific conditions and configurations of temperature, surfaces and mixes in controlled concentration of miscibles and immiscibles substances like the salt saturated solution, alcohol and silicon oil (C_6H_18O_2Si). The hydrophobic surfaces used on those observations are thin glasses coated with ITO (Indium Tin Oxide), 3M ECG-1700 w...

  16. Learn More Breathe Better

    Centers for Disease Control (CDC) Podcasts

    2011-11-16

    Chronic obstructive pulmonary disease (COPD) is a serious lung disease that makes breathing very difficult and can affect your quality of life. Learn the causes of COPD and what you can do to prevent it.  Created: 11/16/2011 by National Center for Chronic Disease Prevention and Health Promotion, Division of Adult and Community Health (NCCDPHP, DACH).   Date Released: 11/16/2011.

  17. Analytical Validation of Accelerator Mass Spectrometry for Pharmaceutical Development: the Measurement of Carbon-14 Isotope Ratio.

    Energy Technology Data Exchange (ETDEWEB)

    Keck, B D; Ognibene, T; Vogel, J S

    2010-02-05

    Accelerator mass spectrometry (AMS) is an isotope based measurement technology that utilizes carbon-14 labeled compounds in the pharmaceutical development process to measure compounds at very low concentrations, empowers microdosing as an investigational tool, and extends the utility of {sup 14}C labeled compounds to dramatically lower levels. It is a form of isotope ratio mass spectrometry that can provide either measurements of total compound equivalents or, when coupled to separation technology such as chromatography, quantitation of specific compounds. The properties of AMS as a measurement technique are investigated here, and the parameters of method validation are shown. AMS, independent of any separation technique to which it may be coupled, is shown to be accurate, linear, precise, and robust. As the sensitivity and universality of AMS is constantly being explored and expanded, this work underpins many areas of pharmaceutical development including drug metabolism as well as absorption, distribution and excretion of pharmaceutical compounds as a fundamental step in drug development. The validation parameters for pharmaceutical analyses were examined for the accelerator mass spectrometry measurement of {sup 14}C/C ratio, independent of chemical separation procedures. The isotope ratio measurement was specific (owing to the {sup 14}C label), stable across samples storage conditions for at least one year, linear over 4 orders of magnitude with an analytical range from one tenth Modern to at least 2000 Modern (instrument specific). Further, accuracy was excellent between 1 and 3 percent while precision expressed as coefficient of variation is between 1 and 6% determined primarily by radiocarbon content and the time spent analyzing a sample. Sensitivity, expressed as LOD and LLOQ was 1 and 10 attomoles of carbon-14 (which can be expressed as compound equivalents) and for a typical small molecule labeled at 10% incorporated with {sup 14}C corresponds to 30 fg

  18. 40 CFR 721.9928 - Urea, tetraethyl-.

    Science.gov (United States)

    2010-07-01

    ... 40 Protection of Environment 30 2010-07-01 2010-07-01 false Urea, tetraethyl-. 721.9928 Section... Substances § 721.9928 Urea, tetraethyl-. (a) Chemical substance and significant new uses subject to reporting. (1) The chemical substance identified as urea, tetraethyl- (PMN P-94-1017; CAS No. 1187-03-7)...

  19. 40 CFR 721.9892 - Alkylated urea.

    Science.gov (United States)

    2010-07-01

    ... 40 Protection of Environment 30 2010-07-01 2010-07-01 false Alkylated urea. 721.9892 Section 721... Alkylated urea. (a) Chemical substance and significant new uses subject to reporting. (1) The chemical substance identified generically as an alkylated urea (PMN P-93-1649) is subject to reporting under...

  20. Clinical utility of breath ammonia for evaluation of ammonia physiology in healthy and cirrhotic adults.

    Science.gov (United States)

    Spacek, Lisa A; Mudalel, Matthew; Tittel, Frank; Risby, Terence H; Solga, Steven F

    2015-12-01

    Blood ammonia is routinely used in clinical settings to assess systemic ammonia in hepatic encephalopathy and urea cycle disorders. Despite its drawbacks, blood measurement is often used as a comparator in breath studies because it is a standard clinical test. We sought to evaluate sources of measurement error and potential clinical utility of breath ammonia compared to blood ammonia. We measured breath ammonia in real time by quartz enhanced photoacoustic spectrometry and blood ammonia in 10 healthy and 10 cirrhotic participants. Each participant contributed 5 breath samples and blood for ammonia measurement within 1 h. We calculated the coefficient of variation (CV) for 5 breath ammonia values, reported medians of healthy and cirrhotic participants, and used scatterplots to display breath and blood ammonia. For healthy participants, mean age was 22 years (±4), 70% were men, and body mass index (BMI) was 27 (±5). For cirrhotic participants, mean age was 61 years (±8), 60% were men, and BMI was 31 (±7). Median blood ammonia for healthy participants was within normal range, 10 μmol L(-1) (interquartile range (IQR), 3-18) versus 46 μmol L(-1) (IQR, 23-66) for cirrhotic participants. Median breath ammonia was 379 pmol mL(-1) CO2 (IQR, 265-765) for healthy versus 350 pmol mL(-1) CO2 (IQR, 180-1013) for cirrhotic participants. CV was 17  ±  6%. There remains an important unmet need in the evaluation of systemic ammonia, and breath measurement continues to demonstrate promise to fulfill this need. Given the many differences between breath and blood ammonia measurement, we examined biological explanations for our findings in healthy and cirrhotic participants. We conclude that based upon these preliminary data breath may offer clinically important information this is not provided by blood ammonia.

  1. 42 CFR 84.81 - Compressed breathing gas and liquefied breathing gas containers; minimum requirements.

    Science.gov (United States)

    2010-10-01

    ... 42 Public Health 1 2010-10-01 2010-10-01 false Compressed breathing gas and liquefied breathing... APPROVAL OF RESPIRATORY PROTECTIVE DEVICES Self-Contained Breathing Apparatus § 84.81 Compressed breathing gas and liquefied breathing gas containers; minimum requirements. (a) Compressed breathing gas...

  2. Tongue Scrapers Only Slightly Reduce Bad Breath

    Science.gov (United States)

    ... your desktop! more... Tongue Scrapers Only Slightly Reduce Bad Breath Article Chapters Tongue Scrapers Only Slightly Reduce ... oral cavity. Reviewed: January 2012 Related Articles: Halitosis (Bad Breath) Do You Have Traveler's Breath? Does a ...

  3. Breath in the technoscientific imaginary.

    Science.gov (United States)

    Rose, Arthur

    2016-12-01

    Breath has a realist function in most artistic media. It serves to remind the reader, the viewer or the spectator of the exigencies of the body. In science fiction (SF) literature and films, breath is often a plot device for human encounters with otherness, either with alien peoples, who may not breathe oxygen, or environments, where there may not be oxygen to breathe. But while there is a technoscientific quality to breath in SF, especially in its attention to physiological systems, concentrating on the technoscientific threatens to occlude other, more affective aspects raised by the literature. In order to supplement the tendency to read SF as a succession of technoscientific accounts of bodily experience, this paper recalls how SF texts draw attention to the affective, non-scientific qualities of breath, both as a metonym for life and as a metaphor for anticipation. Through an engagement with diverse examples from SF literature and films, this article considers the tension between technoscientific and affective responses to breath in order to demonstrate breath's co-determinacy in SF's blending of scientific and artistic discourses.

  4. BREATHE to Understand©

    Science.gov (United States)

    Swisa, Maxine

    2015-01-01

    BREATHE is an acronym for Breathe, Reflect, Empathize, Accept, Thank, Hearten, Engage. The addition of Understand allows for a holistic approach to living a healthy and balanced life both inside and outside the classroom. This paper took form as a result of my personal, spiritual journey, as well as my teaching practice. I noticed that the…

  5. A 20-minute breath test for helicobacter pylori

    Energy Technology Data Exchange (ETDEWEB)

    Marshall, B.J.; Plankey, M.W.; Hoffman, S.R.; Boyd, C.L.; Dye, K.R.; Frierson, H.F. Jr.; Guerrant, R.L.; McCallum, R.W. (Univ. of Virginia Health Sciences Center, Charlottesville (USA))

    1991-04-01

    In this study, we evaluated a simplified rapid {sup 14}C-urea breath test for the diagnosis of Helicobacter pylori. Fasting patients undergoing initial assessment for H. pylori drank 5 microCi of {sup 14}C-urea in 20 ml of water. Breath was collected at intervals for 30 min. Samples were counted in a beta-counter, and the results were expressed as counts per minute (cpm). In the same week, patients underwent endoscopy, and a blinded investigator examined biopsy samples of gastric mucosa by culture and histology for H. pylori. There were 49 H. pylori-negative (HP-) and 104 H. pylori-positive (HP+) patients in the study. HP+ patients expired a mean of 4398 cpm (SD 2468) per mmol CO{sub 2} in a sample taken 20 min after ingestion of the isotope. In contrast, HP--patients expired only 340 cpm (SD 196). If the mean +3 SD of HP- patients was used as a cutoff value, the 20-minute sample gave a sensitivity of 97% and a specificity of 100% for detecting H. pylori. The radiation exposure from this test is less than 1% of that received from an upper gastrointestinal series, and the short collection time makes it both convenient and cost effective.

  6. FMWC Radar for Breath Detection

    DEFF Research Database (Denmark)

    Suhr, Lau Frejstrup; Tafur Monroy, Idelfonso; Vegas Olmos, Juan José

    We report on the experimental demonstration of an FMCW radar operating in the 25.7 - 26.6 GHz range with a repetition rate of 500 sweeps per second. The radar is able to track the breathing rate of an adult human from a distance of 1 meter. The experiments have utilized a 50 second recording window...... to accurately track the breathing rate. The radar utilizes a saw tooth modulation format and a low latency receiver. A breath tracking radar is useful both in medical scenarios, diagnosing disorders such as sleep apnea, and for home use where the user can monitor its health. Breathing is a central part of every...... radar chip which, through the use of a simple modulation scheme, is able to measure the breathing rate of an adult human from a distance. A high frequency output makes sure that the radar cannot penetrate solid obstacles which is a wanted feature in private homes where people therefore cannot measure...

  7. Applications of external cavity diode laser-based technique to noninvasive clinical diagnosis using expired breath ammonia analysis: chronic kidney disease, epilepsy

    Science.gov (United States)

    Bayrakli, Ismail; Turkmen, Aysenur; Akman, Hatice; Sezer, M. Tugrul; Kutluhan, Suleyman

    2016-08-01

    An external cavity laser (ECL)-based off-axis cavity-enhanced absorption spectroscopy was applied to noninvasive clinical diagnosis using expired breath ammonia analysis: (1) the correlation between breath ammonia levels and blood parameters related to chronic kidney disease (CKD) was investigated and (2) the relationship between breath ammonia levels and blood concentrations of valproic acid (VAP) was studied. The concentrations of breath ammonia in 15 healthy volunteers, 10 epilepsy patients (before and after taking VAP), and 27 patients with different stages of CKD were examined. The range of breath ammonia levels was 120 to 530 ppb for healthy subjects and 710 to 10,400 ppb for patients with CKD. There was a statistically significant positive correlation between breath ammonia concentrations and urea, blood urea nitrogen, creatinine, or estimated glomerular filtration rate in 27 patients. It was demonstrated that taking VAP gave rise to increasing breath ammonia levels. A statistically significant difference was found between the levels of exhaled ammonia (NH3) in healthy subjects and in patients with epilepsy before and after taking VAP. The results suggest that our breath ammonia measurement system has great potential as an easy, noninvasive, real-time, and continuous monitor of the clinical parameters related to epilepsy and CKD.

  8. Almagate interference in breath test results for the diagnosis of Helicobacter pylori infection

    Directory of Open Access Journals (Sweden)

    Carles Pons

    2014-08-01

    Full Text Available Background: Infection by Helicobacter pylori is common and affects both genders at any age. The 13C-urea breath test is a widely used test for the diagnosis of this infection. However, multiple drugs used for the treatment of Helicobacter pylori infection symptoms have interactions with this breath test that generate false negative results. This observational study was to assess the potential interaction between almagate and the breath test. Methods: Thirty subjects on almagate therapy who underwent a breath test were included. If the result was negative, almagate was withdrawn for a month and the breath test was then repeated. Results: In general, 51.9 % of assessed subjects had a negative result after the first test, and 100 % of these also had a negative result after the second test. Conclusions: It was concluded that the use of almagate does not interfere in breath test results. These results provide a drug therapy option for the treatment of symptoms associated with Helicobacter pylori infection during the diagnostic process.

  9. Visualizing Breath using Digital Holography

    Science.gov (United States)

    Hobson, P. R.; Reid, I. D.; Wilton, J. B.

    2013-02-01

    Artist Jayne Wilton and physicists Peter Hobson and Ivan Reid of Brunel University are collaborating at Brunel University on a project which aims to use a range of techniques to make visible the normally invisible dynamics of the breath and the verbal and non-verbal communication it facilitates. The breath is a source of a wide range of chemical, auditory and physical exchanges with the direct environment. Digital Holography is being investigated to enable a visually stimulating articulation of the physical trajectory of the breath as it leaves the mouth. Initial findings of this research are presented. Real time digital hologram replay allows the audience to move through holographs of breath-born particles.

  10. Urea in Weaver Ant Feces

    DEFF Research Database (Denmark)

    Vidkjaer, Nanna H.; Wollenweber, Bernd; Jensen, Karl-Martin V.;

    2016-01-01

    investigate the interactions of weaver ants with the host plants with respect to plant nutrition. Here, we report the identification and quantification of urea, a highly effective foliar nutrient present in the fecal depositions of O. smaragdina. Feces samples obtained from six O. smaragdina colonies were......Weaver ants are tropical insects that nest in tree canopies, and for centuries these ants have been used for pest control in tropical orchards. Trees hosting weaver ants might benefit not only from the pest protective properties of these insects but also an additional supply of nutrients from ant...

  11. 21 CFR 184.1923 - Urea.

    Science.gov (United States)

    2010-04-01

    ... 21 Food and Drugs 3 2010-04-01 2009-04-01 true Urea. 184.1923 Section 184.1923 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) FOOD FOR HUMAN... Substances Affirmed as GRAS § 184.1923 Urea. (a) Urea (CO(NH2)2, CAS Reg. No. 57-13-6) is the diamide...

  12. Study of a method of detection for natural carbon-14 using a liquid scintillator, recent variations in the natural radio-activity due to artificial carbon-14 (1963); Etude d'une methode de detection du carrons 14 naturel, utilisant un scintillateur liquide - variations recentes de l'activite naturelle dues au carbone 14 artificiel (1963)

    Energy Technology Data Exchange (ETDEWEB)

    Leger, C. [Commissariat a l' Energie Atomique, Saclay (France). Centre d' Etudes Nucleaires

    1963-06-15

    Among the various natural isotopes of carbon, a radioactive isotope, carbon-14, is formed by the action of secondary neutrons from cosmic rays on nitrogen in the air. Until 1950, the concentration of this isotope in ordinary carbon underwent weak fluctuations of about 2-3 per cent. The exact measurement of this concentration 6 X 10{sup 12} Ci/gm of carbon, and of its fluctuations, are difficult and in the first part of this report a highly sensitive method is given using a liquid scintillator. Since 1950 this natural activity has shown large fluctuations because of the carbon-14 formed during nuclear explosions, and in the second part, the evolution in France of this specific activity of carbon in the atmosphere and biosphere is examined. In the last part is studied the local increase in carbon activity in the atmosphere around the Saclay site, an increase caused by the carbon-14 given off as C{sup 14}O{sub 2}, by the reactors cooled partially with exterior air. (author) [French] Parmi les differents isotopes naturels du carbone, un isotope radioactif, le carbone 14, est forme par l'action de neutrons secondaires due aux rayons cosmiques sir l'azote de l'air. Jusqu'en 1950, la concentration de cet isotope dans le carbone ordinaire est soumise a des fluctuations de faible amplitude, de l'ordre de 2 a 3 pour cent. Les mesures precises de cette concentration, 6. 10{sup -12} Ci/g de carbone, et de ses fluctuations sont delicates, et dans la premiere partie de ce rapport, on decrit une methode de detection a grande sensibilite utilisant un scintillateur liquide. Depuis 1950, cette activite naturelle subit des fluctuations importantes dues au carbone 14 forme lors des explosions nucleaires, et dans la seconde partie, on examine l'evolution en France de l'activite specifique du carbone de l'atmosphere et ce la biosphere. Dans la derniere partie, on etudie l'accroissement local de l'activite du carbone de l'air aux

  13. Urea: new questions about an ancient solute.

    Science.gov (United States)

    Bagnasco, S M

    2000-01-01

    Urea recycling and counter-current exchange within the renal tubular, vascular and interstitial compartments help maintain high levels of this solute in the renal medulla, that are crucial for the production of concentrated urine. The role of urea in physiological and pathological conditions is still unclear, although new information is becoming available. Several urea transporters have been identified that mediate facilitated transport of urea across biological membranes in the mammalian kidney, in amphibians, and in elasmobranchs. Evidence that urea transporters may be expressed in other mammalian organs is also beginning to emerge. The mechanisms involved in the regulation of urea transport are incompletely understood. In this respect, the structural and functional characterization of individual transporters is providing the basis to identify specific regulatory factors. Urea can be viewed as a perturbing osmolyte in the renal inner medulla, and the mechanisms of adaptation of renal cells to high concentration of this destabilizing solute are being investigated. Urea-specific signaling pathways have been identified, that could contribute to clarify how cells handle urea.

  14. Urea and its formation in coelacanth liver.

    Science.gov (United States)

    Brown, G W; Brown, S G

    1967-02-01

    Urea occurs in liver of the coelacanth Latimeria chalumnae to the extent of about 1.7 percent by weight. It was determined quantitatively by reaction with 1-phenyl-1,2-propanedione-2-oxime (Archibald reagent) and by measurement of ammonia released upon treatment with urease. Arginase and ornithine carbamoyltransferase, enzymes instrumental in the formation of urea in typical ureotelic vertebrates, occur in homogenates of coelacanth liver. Formed in part by the ornithine-urea cycle, urea may have an osmoregulatory function in the coelacanth as it has in elasmobranchs.

  15. Synthesis of carbon-14 analogue of 1,5 diaryl-5-[{sup 14}C]-1,2,3-triazoles

    Energy Technology Data Exchange (ETDEWEB)

    Matloubi, Hojatollah E-mail: hmatloubi@aeoi.org.ir; Shafiee, Abbas; Saemian, Nader; Shirvani, Gholamhossein; Daha, Fariba Johari

    2004-05-01

    Two 1,2,3-triazole anticonvulsants, 1-(4-methylsulfone-phenyl)-5-(4-methyl-phenyl)-1,2,3-triazole and 1-(4-methylsulfone-phenyl)-5-phenyl-1,2,3-triazole, both labeled with carbon-14 in the 5-position were prepared from para-tolunitrile-[cyano-{sup 14}C] and benzonitrile-[cyano-{sup 14}C], respectively.

  16. Biobased carbon content of resin extracted from polyethylene composite by carbon-14 concentration measurements using accelerator mass spectrometry

    OpenAIRE

    Taguchi, Kazuhiro; Kunioka, Masao; Funabashi, Masahiro; Ninomiya, Fumi

    2014-01-01

    An estimation procedure for biobased carbon content of polyethylene composite was studied using carbon-14 (14C) concentration ratios as measured by accelerated mass spectrometry (AMS). Prior to the measurement, additives and fillers in composites should be removed because they often contain a large amount of biobased carbon and may shift the estimation. Samples of resin with purity suitable for measurement were isolated from composites with a Soxhlet extractor using heated cyclohexanone. Afte...

  17. LIMITED OXIDATION OF IRRADIATED GRAPHITE WASTE TO REMOVE SURFACE CARBON-14

    Directory of Open Access Journals (Sweden)

    TARA E. SMITH

    2013-04-01

    Full Text Available Large quantities of irradiated graphite waste from graphite-moderated nuclear reactors exist and are expected to increase in the case of High Temperature Reactor (HTR deployment [1,2]. This situation indicates the need for a graphite waste management strategy. Of greatest concern for long-term disposal of irradiated graphite is carbon-14 (14C, with a half-life of 5730 years. Fachinger et al. [2] have demonstrated that thermal treatment of irradiated graphite removes a significant fraction of the 14C, which tends to be concentrated on the graphite surface. During thermal treatment, graphite surface carbon atoms interact with naturally adsorbed oxygen complexes to create COx gases, i.e. “gasify” graphite. The effectiveness of this process is highly dependent on the availability of adsorbed oxygen compounds. The quantity and form of adsorbed oxygen complexes in pre- and post-irradiated graphite were studied using Time of Flight Secondary Ion Mass Spectrometry (ToF-SIMS and X-ray Photoelectron Spectroscopy (XPS in an effort to better understand the gasification process and to apply that understanding to process optimization. Adsorbed oxygen fragments were detected on both irradiated and unirradiated graphite; however, carbon-oxygen bonds were identified only on the irradiated material. This difference is likely due to a large number of carbon active sites associated with the higher lattice disorder resulting from irradiation. Results of XPS analysis also indicated the potential bonding structures of the oxygen fragments removed during surface impingement. Ester- and carboxyl- like structures were predominant among the identified oxygen-containing fragments. The indicated structures are consistent with those characterized by Fanning and Vannice [3] and later incorporated into an oxidation kinetics model by El-Genk and Tournier [4]. Based on the predicted desorption mechanisms of carbon oxides from the identified compounds, it is expected that a

  18. Standardization of exhaled breath condensate (EBC) collection using a feedback regulated breathing pattern

    Science.gov (United States)

    Collection of exhaled breath condensate (EBC) fluid by cooling of expired breath is a potentially valuable approach for the detection of biomarkers associated with disease or exposure to xenobiotics. EBC is generally collected using unregulated breathing patterns, perceived to el...

  19. Effects of diaphragm breathing exercise and feedback breathing exercise on pulmonary function in healthy adults

    OpenAIRE

    Yong, Min-Sik; Lee, Hae-Yong; Lee, Yun-Seob

    2017-01-01

    [Purpose] The present study investigated effects of diaphragm breathing exercise and feedback breathing exercise on respiratory function. [Subjects and Methods] Thirty-one subjects were randomly assigned to two groups; the feedback breathing exercise group and the maneuver-diaphragm exercise group. The feedback breathing exercise group was asked to breathe with feedback breathing device, and the maneuver-diaphragm exercise group was asked to perform diaphragm respiration. Respiratory function...

  20. [Urea formation in the after operational liver].

    Science.gov (United States)

    Savilov, P N

    2016-01-01

    The effect of resection of the left lobe of the liver (LR, 15-20% og the organ weight) on hepatic urea formation was investigated in 84 albino rats. The objects of study were the surgery left (LLP), inoperable middle (MLP) lobe of the liver, blood (aorta, v. hepatica, v. porta) and choledochal bile. They studied the urea content. Arginase activity was examined in liver homogenate. On the day 3 and day 7 after resection reduced arginase activity was detected. LR caused a decrease of urea in v. hepatica, but increased urea content in the arterial blood and v. porta. Increase in bile urea on day 7 it was replaced by a decrease observed on day 14 of the postsurgery period. The concentration of urea in the liver on the 3rd day after LR was below the norm, and on the 7th and 14th day was within it. The results indicate a violation of urea operated by hepatocytes of the liver and extrahepatic activation mechanisms of the formation of urea.

  1. Urea synthesis in patients with chronic pancreatitis

    DEFF Research Database (Denmark)

    Hamberg, Ole; Sonne, J; Larsen, S

    2001-01-01

    Up-regulation of urea synthesis by amino acids and dietary protein intake may be impaired in patients with chronic pancreatitis (CP) due to the reduced glucagon secretion. Conversely, urea synthesis may be increased as a result of the chronic inflammation. The aims of the study were to determine...

  2. Multiphase Carbon-14 Transport in a Near-Field-Scale Unsaturated Column of Natural Sediments

    Energy Technology Data Exchange (ETDEWEB)

    D. T. Fox; Mitchell A. Plummer; Larry C. Hull; D. Craig Cooper

    2004-03-01

    Wastes buried at the Subsurface Disposal Area (SDA) of the Idaho National Engineering and Environmental Laboratory include activated metals that release radioactive carbon-14 (14C) as they corrode. To better understand 14C phase partitioning and transport in the SDA sediments, we conducted a series of transport experiments using 14C (radio-labeled sodium carbonate) and nonreactive gas (sulfur hexafluoride) and aqueous (bromide and tritiated water) tracers in a large (2.6-m high by 0.9-m diameter) column of sediments similar to those used as cover material at the SDA. We established steady-state unsaturated flow prior to injecting tracers into the column. Tracer migration was monitored using pore-water and pore-gas samples taken from co-located suction lysimeters and gas ports inserted at ~0.3-m intervals along the column’s length. Measurements of 14C discharged from the sediment to the atmosphere (i.e., 14CO2 flux) indicate a positive correlation between CO2 partial pressure (pCO2) in the column and changes in 14CO2 flux. Though 14CO2 diffusion is expected to be independent of pCO2, changes of pCO2 affect pore water chemistry sufficiently to affect aqueous/gas phase 14C partitioning and consequently 14C2 flux. Pore-water and -gas 14C activity measurements provide an average aqueous/gas partitioning ratio, Kag, of 4.5 (±0.3). This value is consistent with that calculated using standard carbonate equilibrium expressions with measured pH, suggesting the ability to estimate Kag from carbonate equilibrium. One year after the 14C injection, the column was cored and solid-phase 14C activity was measured. The average aqueous/solid partition coefficient, Kd, (1.6 L kg-1) was consistent with those derived from small-scale and short-term batch and column experiments using SDA sediments, suggesting that bench-scale measurements are a valid means of estimating aqueous/solid partitioning at the much larger spatial scale considered in these meso-scale experiments. However

  3. Taking a deep breath

    Directory of Open Access Journals (Sweden)

    Carlos Renato Zacharias

    2012-12-01

    be paid to language revision and reference citation. Together with its authors and readers, IJHDR contributes to the development of a kind of knowledge close to the borders of science. Therefore, to establish a valid scientific background, the articles must be clearly written, and based on sound assumptions. High-visibility for articles is a fundamental aspect desired by all authors. As an open and free access journal, IJHDR meets that condition, and we are planning to make our influence and visibility even wider. Inclusion in the major databases has paramount importance in the academic milieu, however, it should be considered as a consequence, rather than a goal. In 2013, IJHDR will chair a collaborative project with several research institutions aiming to deliver information everywhere, increasing the visibility of the published articles. Thus, now it is the time to take a deep breath, relax, and prepare you for the forthcoming work! See you in 2013!

  4. Ammonia volatilization from coated urea forms

    Directory of Open Access Journals (Sweden)

    Carlos Antonio Costa do Nascimento

    2013-08-01

    Full Text Available Nitrogen fertilization is a major component of the cost of agricultural production, due to the high cost and low efficiency of fertilizers. In the case of urea, the low efficiency is mainly due to losses by volatilization, which are more pronounced in cultivation systems in which plant residues are left on the soil. The objective of this work was to compare the influence of urea coated with sulfur or boric acid and copper sulfate with conventional N fertilizers on N volatilization losses in sugar cane harvested after stubble burning. The sources urea, sulfur-coated urea, urea coated with boric acid and copper sulfate, as well as nitrate and ammonium sulfate, were tested at amounts containing N rates of 120 kg ha-1 N. The integration of new technologies in urea fertilization can reduce N losses by volatilization. These losses were most reduced when using nitrate and ammonium sulfate. The application of a readily acidified substance (boric acid to urea was more efficient in reducing volatilization losses and nutrient removal by sugar cane than that of a substance with gradual acidification (elemental sulfur.

  5. Comparative transport efficiencies of urea analogues through urea transporter UT-B.

    Science.gov (United States)

    Zhao, Dan; Sonawane, N D; Levin, Marc H; Yang, Baoxue

    2007-07-01

    Expression of urea transporter UT-B confers high urea permeability to mammalian erythrocytes. Erythrocyte membranes also permeate various urea analogues, suggesting common transport pathways for urea and structurally similar solutes. In this study, we examined UT-B-facilitated passage of urea analogues and other neutral small solutes by comparing transport properties of wildtype to UT-B-deficient mouse erythrocytes. Stopped-flow light-scattering measurements indicated high UT-B permeability to urea and chemical analogues formamide, acetamide, methylurea, methylformamide, ammonium carbamate, and acrylamide, each with P(s)>5.0 x 10(-6) cm/s at 10 degrees C. UT-B genetic knockout and phloretin treatment of wildtype erythrocytes similarly reduced urea analogue permeabilities. Strong temperature dependencies of formamide, acetamide, acrylamide and butyramide transport across UT-B-null membranes (E(a)>10 kcal/mol) suggested efficient diffusion of these amides across lipid bilayers. Urea analogues dimethylurea, acryalmide, methylurea, thiourea and methylformamide inhibited UT-B-mediated urea transport by >60% in the absence of transmembrane analogue gradients, supporting a pore-blocking mechanism of UT-B inhibition. Differential transport efficiencies of urea and its analogues through UT-B provide insight into chemical interactions between neutral solutes and the UT-B pore.

  6. First-time urea breath tests performed at home by 36,629 patients

    DEFF Research Database (Denmark)

    Dahlerup, Søren; Andersen, Rikke Charlotte; Nielsen, Birgitte Sperling Wilms;

    2011-01-01

    , positive H. pylori declined over the time course of the study (women: 19.6% in 2003 to 17.6% in 2009, p H. pylori results than younger patients. CONCLUSIONS: A test......-and-treat system was possible to implement that allowed patients to perform UBTs at their homes. The results of the first-time UBTs demonstrated that approximately one of five patients who presented with dyspepsia in the clinical setting of Danish primary care was infected with H. pylori....

  7. Submarines, Spacecraft, and Exhaled Breath

    Science.gov (United States)

    The International Association of Breath Research (IABR) meetings are an eclectic gathering of researchers in the medical, environmental and instrumentation fields; our focus is on human health as assessed by the measurement and interpretation of trace chemicals in human exhaled b...

  8. Breath-holding and its breakpoint.

    Science.gov (United States)

    Parkes, M J

    2006-01-01

    This article reviews the basic properties of breath-holding in humans and the possible causes of the breath at breakpoint. The simplest objective measure of breath-holding is its duration, but even this is highly variable. Breath-holding is a voluntary act, but normal subjects appear unable to breath-hold to unconsciousness. A powerful involuntary mechanism normally overrides voluntary breath-holding and causes the breath that defines the breakpoint. The occurrence of the breakpoint breath does not appear to be caused solely by a mechanism involving lung or chest shrinkage, partial pressures of blood gases or the carotid arterial chemoreceptors. This is despite the well-known properties of breath-hold duration being prolonged by large lung inflations, hyperoxia and hypocapnia and being shortened by the converse manoeuvres and by increased metabolic rate. Breath-holding has, however, two much less well-known but important properties. First, the central respiratory rhythm appears to continue throughout breath-holding. Humans cannot therefore stop their central respiratory rhythm voluntarily. Instead, they merely suppress expression of their central respiratory rhythm and voluntarily 'hold' the chest at a chosen volume, possibly assisted by some tonic diaphragm activity. Second, breath-hold duration is prolonged by bilateral paralysis of the phrenic or vagus nerves. Possibly the contribution to the breakpoint from stimulation of diaphragm muscle chemoreceptors is greater than has previously been considered. At present there is no simple explanation for the breakpoint that encompasses all these properties.

  9. Detection of Helicobacter pylori infection by examination of human breath odor using electronic nose Bloodhound-214ST

    Science.gov (United States)

    Shnayder, E. P.; Moshkin, M. P.; Petrovskii, D. V.; Shevela, A. I.; Babko, A. N.; Kulikov, V. G.

    2009-05-01

    Our aim was to examine the possibility of use e-nose Bloodhound-214ST to determine presence or absence of H. pylori infection using exhalation samples of patients. Breath samples were collected twice: at baseline and after oral administration of 500 mg of urea. H. pylori status of patients was confirmed by antral biopsy. Using two approaches for the data analysis we showed the possibility to distinguish H. pylori free and infected patients.

  10. Dissolved Organic Carbon 14C in Southern Nevada Groundwater and Implications for Groundwater Travel Times

    Energy Technology Data Exchange (ETDEWEB)

    Hershey, Ronald L. [Nevada University, Reno, NV (United States). Desert Research Institute; Fereday, Wyall [Nevada University, Reno, NV (United States). Desert Research Institute; Thomas, James M [Nevada University, Reno, NV (United States). Desert Research Institute

    2016-08-01

    Dissolved inorganic carbon (DIC) carbon-14 (14C) ages must be corrected for complex chemical and physical reactions and processes that change the amount of 14C in groundwater as it flows from recharge to downgradient areas. Because of these reactions, DIC 14C can produce unrealistically old ages and long groundwater travel times that may, or may not, agree with travel times estimated by other methods. Dissolved organic carbon (DOC) 14C ages are often younger than DIC 14C ages because there are few chemical reactions or physical processes that change the amount of DOC 14C in groundwater. However, there are several issues that create uncertainty in DOC 14C groundwater ages including limited knowledge of the initial (A0) DOC 14C in groundwater recharge and potential changes in DOC composition as water moves through an aquifer. This study examines these issues by quantifying A0 DOC 14C in recharge areas of southern Nevada groundwater flow systems and by evaluating changes in DOC composition as water flows from recharge areas to downgradient areas. The effect of these processes on DOC 14C groundwater ages is evaluated and DOC and DIC 14C ages are then compared along several southern Nevada groundwater flow paths. Twenty-seven groundwater samples were collected from springs and wells in southern Nevada in upgradient, midgradient, and downgradient locations. DOC 14C for upgradient samples ranged from 96 to 120 percent modern carbon (pmc) with an average of 106 pmc, verifying modern DOC 14C ages in recharge areas, which decreases uncertainty in DOC 14C A0 values, groundwater ages, and travel times. The HPLC spectra of groundwater along a flow path in the Spring Mountains show the same general pattern indicating that the DOC compound composition does not change along this flow path

  11. Neural mechanisms underlying breathing complexity.

    Directory of Open Access Journals (Sweden)

    Agathe Hess

    Full Text Available Breathing is maintained and controlled by a network of automatic neurons in the brainstem that generate respiratory rhythm and receive regulatory inputs. Breathing complexity therefore arises from respiratory central pattern generators modulated by peripheral and supra-spinal inputs. Very little is known on the brainstem neural substrates underlying breathing complexity in humans. We used both experimental and theoretical approaches to decipher these mechanisms in healthy humans and patients with chronic obstructive pulmonary disease (COPD. COPD is the most frequent chronic lung disease in the general population mainly due to tobacco smoke. In patients, airflow obstruction associated with hyperinflation and respiratory muscles weakness are key factors contributing to load-capacity imbalance and hence increased respiratory drive. Unexpectedly, we found that the patients breathed with a higher level of complexity during inspiration and expiration than controls. Using functional magnetic resonance imaging (fMRI, we scanned the brain of the participants to analyze the activity of two small regions involved in respiratory rhythmogenesis, the rostral ventro-lateral (VL medulla (pre-Bötzinger complex and the caudal VL pons (parafacial group. fMRI revealed in controls higher activity of the VL medulla suggesting active inspiration, while in patients higher activity of the VL pons suggesting active expiration. COPD patients reactivate the parafacial to sustain ventilation. These findings may be involved in the onset of respiratory failure when the neural network becomes overwhelmed by respiratory overload We show that central neural activity correlates with airflow complexity in healthy subjects and COPD patients, at rest and during inspiratory loading. We finally used a theoretical approach of respiratory rhythmogenesis that reproduces the kernel activity of neurons involved in the automatic breathing. The model reveals how a chaotic activity in

  12. Release Kinetics of Urea from Polymer Coated Urea and Its Relationship with Coating Penetrability

    Institute of Scientific and Technical Information of China (English)

    ZHANG Hai-jun; WU Zhi-jie; CHEN Li-jun; LIANG Wen-ju

    2003-01-01

    Four kinds of polymer coated urea (PCU) were put in distilled water at 30C to determine the variation of coating penetrability and give a precise description of the urea release kinetics. The urea release from PCU could be divided into four stages: lag stage, swell stage, steady stage and decay stage. The release rate coefficient K, a measure of coating penetrability, was linearly increased at swell stage, but almost not variable at steady stage. At decay stage, the relation of K to time t could be described by the equation K= mtn-1(where m and n are the coefficients). When n>1, the coating penetrability was gradually increased, and the urea release from PCU was accelerated; when n=1, the coating penetrability was steady, and the urea release from PCU obeyed the first-order kinetics; and when n<1, the coating penetrability was gradually decreased,and the urea release from PCU was delayed, resulting in a significant "tailing effect".

  13. Urea and deuterium mixtures at high pressures

    Energy Technology Data Exchange (ETDEWEB)

    Donnelly, M., E-mail: m.donnelly-2@sms.ed.ac.uk; Husband, R. J.; Frantzana, A. D.; Loveday, J. S. [Centre for Science at Extreme Conditions and School of Physics and Astronomy, The University of Edinburgh, Erskine Williamson Building, Peter Guthrie Tait Road, The King’s Buildings, Edinburgh EH9 3FD (United Kingdom); Bull, C. L. [ISIS, Rutherford Appleton Laboratory, Oxford Harwell, Didcot OX11 0QX (United Kingdom); Klotz, S. [IMPMC, CNRS UMR 7590, Université P and M Curie, 4 Place Jussieu, 75252 Paris (France)

    2015-03-28

    Urea, like many network forming compounds, has long been known to form inclusion (guest-host) compounds. Unlike other network formers like water, urea is not known to form such inclusion compounds with simple molecules like hydrogen. Such compounds if they existed would be of interest both for the fundamental insight they provide into molecular bonding and as potential gas storage systems. Urea has been proposed as a potential hydrogen storage material [T. A. Strobel et al., Chem. Phys. Lett. 478, 97 (2009)]. Here, we report the results of high-pressure neutron diffraction studies of urea and D{sub 2} mixtures that indicate no inclusion compound forms up to 3.7 GPa.

  14. Surface modified silicon nanochannel for urea sensing

    CERN Document Server

    Chen, Yu; Hong, Mi; Erramilli, Shyamsunder; Mohanty, Pritiraj

    2008-01-01

    Silicon nanowires have been surface functionalized with the enzyme urease for biosensor applications to detect and quantify urea concentration. The device is nanofabricated from a silicon on insulator (SOI) wafer with a top down lithography approach. The differential conductance of silicon nanowires can be tuned for optimum performance using the source drain bias voltage, and is sensitive to urea at low concentration. The experimental results show a linear relationship between surface potential change and urea concentration in the range of 0.1 to 0.68 mM. The sensitivity of our devices shows high reproducibility with time and different measurement conditions. The nanowire urea biosensor offers the possibility of high quality, reusable enzyme sensor array integration with silicon based circuits.

  15. High nonlinear optical anisotropy of urea nanofibers

    Science.gov (United States)

    Isakov, D.; de Matos Gomes, E.; Belsley, M.; Almeida, B.; Martins, A.; Neves, N.; Reis, R.

    2010-07-01

    Nanofibers consisting of the optically nonlinear organic molecule urea embedded in both poly(ethylene oxide) (PEO) and poly(vinyl alcohol) (PVA) polymers were produced by the electrospinning technique. The second-harmonic generation produced by aligned fiber mats of these materials displays a strong dependence on the polarization of the incident light. In PVA-urea nanofibers the effectiveness in generating of the second-harmonic light is as high as that of a pure urea powder with an average grain size of 110 μm. The results suggest that single crystalline urea nanofibers were achieved with a long-range crystalline order extending into the range of 2-4 μm with PVA as the host polymer.

  16. Evaluation of excess carbon 14 and strontium 90 data for suitability to test two-dimensional stratospheric models

    Science.gov (United States)

    Johnston, Harold

    1989-12-01

    From reports by the Atomic Energy Commission concerning the atmospheric distribution of radionucleides following the nuclear bomb tests of 1958-1959 and 1961-1962, excess carbon 14 data from the period 1959-1970 and strontium 90 data from 1963-1967 are reviewed for possible use as inert tracers to test two-dimensional stratospheric-tropospheric models. Contrary to some views expressed in the literature, it is concluded that the carbon 14 data are suitable to test (1) the altitude (at 4 latitudes) of the transition region between troposphere and stratosphere with respect to transport of an inert tracer, (2) some aspects of transport between the northern and southern hemispheres, (3) horizontal and vertical transport as the vertical profile between 4.5 and 33 km and at 31°N evolves from a skewed Gaussian in 1963 to an almost stair-step profile in 1966, and (4) the long-term one-dimensional aspect of a two-dimensional model over the period 1966-1970. More tentatively, it is concluded that the strontium 90 data may be used as a model for the distribution and gross settling rate of the natural stratospheric aerosol layer between 15 and 25 km. Data from difficultly obtained laboratory reports and suggested initial conditions and boundary conditions are included as a microfiche supplement to this paper.

  17. Detection of Interstellar Urea with Carma

    Science.gov (United States)

    Kuo, H.-L.; Snyder, L. E.; Friedel, D. N.; Looney, L. W.; McCall, B. J.; Remijan, A. J.; Lovas, F. J.; Hollis, J. M.

    2010-06-01

    Urea, a molecule discovered in human urine by H. M. Rouelle in 1773, has a significant role in prebiotic chemistry. Previous BIMA observations have suggested that interstellar urea [(NH_2)_2CO] is a compact hot core molecule such as other large molecules, e.g. methyl formate and acetic acid (2009, 64th OSU Symposium On Molecular Spectroscopy, WI05). We have conducted an extensive search for urea toward the high mass hot molecular core Sgr B2(N-LMH) using CARMA and the IRAM 30 m. Because the spectral lines of heavy molecules like urea tend to be weak and hot cores display lines from a wide range of molecules, a major problem in identifying urea lines is confusion with lines of other molecules. Therefore, it is necessary to detect a number of urea lines and apply sophisticated statistical tests before having confidence in an identification. The 1 mm resolution of CARMA enables favorable coupling of the source size and synthesized beam size, which was found to be essential for the detection of weak signals. The 2.5^"×2^" synthesized beam of CARMA significantly resolves out the contamination by extended emission and reveals the eight weak urea lines that were previously blended with nearby transitions. Our analysis indicates that these lines are likely to be urea since the resulting observed line frequencies are coincident with a set of overlapping connecting urea lines, and the observed line intensities are consistent with the expected line strengths of urea. In addition, we have developed a new statistical approach to examine the spatial correlation between the observed lines by applying the Student T-test to the high resolution channel maps obtained from CARMA. The T-test shows similar spatial distributions from all eight candidate lines, suggesting a common molecular origin, urea. Our T-test method could have a broad impact on the next generation of arrays, such as ALMA, because the new arrays will require a method to systematically determine the credibility of

  18. A Proof of Concept Study to Detect Urease Producing Bacteria in Lungs Using Aerosolized 13C-Urea

    Science.gov (United States)

    Timmins, Graham; Davies, Lea; Heynekamp, Theresa; Harkins, Michelle; Sharp, Zachary D.; Kelly, H. William

    2016-01-01

    This is a “proof of concept” study to determine whether inhalation of 13C-urea can be safely used to detect the presence of urease producing bacteria in the airways of patients with cystic fibrosis (CF) by detecting 13CO2 in breath. This was a prospective, 2-part, open label, single-center, single-arm, single-administration, dose-escalation investigational device exemption trial. First, the safety of 20 and 50 mg inhaled 13C-urea was evaluated in 6 healthy adult participants. Then, 3 adult CF participants colonized with Pseudomonas aeruginosa were enrolled for each dose of inhaled 13C-urea. The safety of inhaled 13C-urea was assessed by spirometry and physical examination. 13C-urea was administered using a jet nebulizer, followed by serial spirometry (10 min and 30 min post inhalation) and collection of exhaled breath at 5, 10, and 15 min post inhalation. There was no clinical significant change in any of the spirometry values compared to baseline in healthy participants and CF patients. Mean of 13CO2/12CO2 delta over baseline (DOB) values in CF participants at 5, 10, and 15 min post inhalation was as follows: 20 mg dose 4‰ (2.2‰–4.9‰), 1‰ (1.0‰–1.4‰), and 1‰ (0.4‰–1.5‰); 50 mg dose: 10‰ (6.2‰–14.5‰), 3‰ (2.1‰–4.3‰), and 1.5‰ (0.6‰–2.3‰). Inhaled 13C-urea for detection of urease producing bacteria was safe, and preliminary data suggest that 13CO2/12CO2 DOB values may be higher in CF patients with P. aeruginosa at 5–10 min after inhalation of 13C-urea. A future direction is to investigate use of inhaled 13C-urea in young children who have difficulty producing sputum for culturing. PMID:27458537

  19. Liquid chromatographic determination of urea in water-soluble urea-formaldehyde fertilizer products and in aqueous urea solutions: collaborative study.

    Science.gov (United States)

    Hojjatie, Michael M; Abrams, Dean E; Parham, Thomas M; Balthrop, J; Beine, R; Dickinson, V; Hartshorn, J; Herald, S; Latimer, G; Padmore, J; Pleasants, S; Riter, K; Roser, R; Schmunck, G; Sensmeier, R; Smith, V; Taylor, L; Volgas, G

    2004-01-01

    Water soluble urea-formaldehyde (UF) fertilizers, manufactured by complex reaction of urea and formaldehyde, typically contain varying amounts of unreacted urea. A liquid chromatography method for the analysis of urea in these products, and in aqueous urea solutions, was collaboratively studied. An amine chromatography column was used to separate the unreacted urea from numerous UF reaction products present in these liquid fertilizers. Unreacted urea was determined by using external urea standards with UV detection at 195 nm. The standards and test samples were prepared in the mobile phase of 85% (v/v) acetonitrile in water. Ten laboratories analyzed 5 different UF-based commercial products containing unreacted urea in the range of 6 to 17% by weight, and 5 different concentrations of urea in water equivalent to commercial products of that nature. The aqueous urea solutions contained 2-20% urea (w/w). The range of s(R) values for the 5 UF-based commercial fertilizers was 0.49-1.02 and the %RSD(R) was 1.94-6.14. The s(R) range for the 5 urea solutions was 0.10 to 0.79 and the %RSD(R) range was 2.54 to 4.88. The average recovery of urea from the aqueous urea solutions was 96-103%. Therefore, this method is capable of monitoring urea nitrogen manufacturers' label claims and total nitrogen claims in those cases where urea is the sole source of plant food nitrogen. Based on the collaborative study data, the authors recommend this method be approved for AOAC Official First Action status.

  20. [Stahl, Leibniz, Hoffmann and breathing].

    Science.gov (United States)

    Carvallo, Sarah

    2006-01-01

    At the beginning of the XVIII th century, Wilhelm Gottfried Leibniz and Friedrich Hoffmann criticize Georg Ernst Stahl's medical theory. They differenciate between unsound and true reasonings. Namely, they validate Stahl's definition of breath but extracting it from its animist basis and placing it in an epistemology obeying to the principle of sufficient reason and to the mechanical model. The stahlian discovery consists in understanding breath as a calorific ventilation against the ancient conception; the iatromechanists recognize its accuracy, but they try then to transpose it to a mechanical model of ventilation. Using it in a different epistemological context implies that they analyze the idea of discovery "true" in its contents, but "wrong" in its hypothesis. It impels to examine the epistemology of medical knowledge, as science and therapeutics, and in its links with the other scientific theories. Thus, if Leibniz as philosopher and Hoffmann as doctor consider Stahl's animism so important, it is because its discoveries question the fundamental principles of medicine.

  1. Effects of diaphragm breathing exercise and feedback breathing exercise on pulmonary function in healthy adults.

    Science.gov (United States)

    Yong, Min-Sik; Lee, Hae-Yong; Lee, Yun-Seob

    2017-01-01

    [Purpose] The present study investigated effects of diaphragm breathing exercise and feedback breathing exercise on respiratory function. [Subjects and Methods] Thirty-one subjects were randomly assigned to two groups; the feedback breathing exercise group and the maneuver-diaphragm exercise group. The feedback breathing exercise group was asked to breathe with feedback breathing device, and the maneuver-diaphragm exercise group was asked to perform diaphragm respiration. Respiratory function was evaluated when a subject sat on a chair comfortably. [Results] There was a significant difference in the functional vital capacity and slow vital capacity before and after all breathing exercises. There was a significant between-group difference in functional vital capacity. However, no between-group difference was found in slow vital capacity. [Conclusion] Diaphragm breathing exercise and feedback breathing exercise can affect respiratory function.

  2. Breathing Modes in Dusty Plasma

    Institute of Scientific and Technical Information of China (English)

    王晓钢; 王爽; 潘秋惠; 刘悦; 贺明峰

    2003-01-01

    Acoustic breathing modes of dusty plasmas have been investigated in a cylindricalsystem with an axial symmetry. The linear wave solution and a "dispersion" relation were derived.It was found that in an infinite area, the mode is reduced to a "classical" dust acoustic wave inthe region away from the center. If the dusty plasma is confined in a finite region, however, thebreathing (or heart-beating) behavior would be found as observed in many experiments.

  3. Running and Breathing in Mammals

    Science.gov (United States)

    Bramble, Dennis M.; Carrier, David R.

    1983-01-01

    Mechanical constraints appear to require that locomotion and breathing be synchronized in running mammals. Phase locking of limb and respiratory frequency has now been recorded during treadmill running in jackrabbits and during locomotion on solid ground in dogs, horses, and humans. Quadrupedal species normally synchronize the locomotor and respiratory cycles at a constant ratio of 1:1 (strides per breath) in both the trot and gallop. Human runners differ from quadrupeds in that while running they employ several phase-locked patterns (4:1, 3:1, 2:1, 1:1, 5:2, and 3:2), although a 2:1 coupling ratio appears to be favored. Even though the evolution of bipedal gait has reduced the mechanical constraints on respiration in man, thereby permitting greater flexibility in breathing pattern, it has seemingly not eliminated the need for the synchronization of respiration and body motion during sustained running. Flying birds have independently achieved phase-locked locomotor and respiratory cycles. This hints that strict locomotor-respiratory coupling may be a vital factor in the sustained aerobic exercise of endothermic vertebrates, especially those in which the stresses of locomotion tend to deform the thoracic complex.

  4. Synthesis and Characterization of Branched Poly(ester urea)s with Different Branch Density

    Science.gov (United States)

    Yu, Jiayi; Becker, Matthew

    2015-03-01

    A new class of L-phenylalanine-based poly(ester urea)s (PEU) was developed that possess tunable mechanical properties, water uptake ability and degradation rates. Our preliminary data has shown that 1,6-hexanediol L - phenylalanine-based poly(ester urea)s possesses an elastic modulus nearly double that of poly(lactic acid). My work details the synthesis of a series of L - phenylalanine-based poly(ester urea)s possessing a variation in diol chain length and in branch density and shows how these subtle structural differences influence the mechanical properties and in vitro biodegradation rates. The elastic moduli span a range of values that overlap with several currently clinically available degradable polymers. Increasingly the diol chain lengths increases the amount of flexible segment in the chemical structure, which results in reduced elastic modulus values and increased values of elongation at break. Increasing the amount of branch monomer incorporated into the system reduces the molecular entanglement, which also results in decreased elastic modulus values and increased values of elongation at break. The L - phenylalanine-based poly(ester urea)s also exhibited a diol length dependent degradation process that varied between 1-5 % over 16 weeks. Compared with PLLA, PEUs degrade more quickly and the rate can be tuned by changing the diol chain length. PEUs absorb more water and the water uptake ability can be tuned by changing the branch density. This work was supported by Akron Functional Materials Center.

  5. Standardization of the TRUE Test imidazolidinyl urea and diazolidinyl urea patches

    DEFF Research Database (Denmark)

    Agner, T; Andersen, Klaus Ejner; Björkner, B;

    2001-01-01

    The preservatives imidazolidinyl urea (IMID, Germall 115) and diazolidinyl urea (DU, Germall II) are commonly used in cosmetic products and are well-known sensitizers. The aim of the present study was to establish the optimal patch test concentration in hydrophilic dried-in vehicle (TRUE Test...

  6. [Tritium- and carbon-14-contents of wines of different vintage from the northern and southern hemisphere (author's transl)].

    Science.gov (United States)

    Fischer, E; Möller, H; Rapp, A; Steffan, H

    1980-10-01

    The carbon-14 and tritium radioactivity contents of up to 19 vintages of German and South African wines were compared. A similar large dependence of the 14C- and of the 3H-activity in the German wine on the nuclear weapon tests of the years 1962/63 was found out. The radioactivity level is also 1977/78 still essential higher than before 1950. The South African wines have been influenced considerably smaller by nuclear explosions. The highest 3H-values were found in the vintage 1963 of the German wine with 5910 pCi/litre and in the vintage 1964 of the South African wine with 510 pCi/litre.

  7. [Breath-analysis tests in gastroenetrological diagnosis].

    Science.gov (United States)

    Caspary, W F

    1975-12-01

    The introduction of a simple method for analysis of 14CO2 in breath allowed a more widely application of breath-tests in the diagnosis of gastroenterological diseases. During a breath-test a 14C-labelled compound is administered orally and 14CO2 is subsequently measured in breath by discontinuous samplings of 14CO2 by virtue of a trapping solution (hyamine hydroxide). Most helpful tests in gastroenterology are the 14C-glycyl-cholate breath test for detecting increased deconjugation of bile acids due to small intestinal bacterial overgrowth or bile acid malabsorption in ileal resection or Crohn's disease of the ileum, the 14C-lactose breath test in lactase deficiency, whereas the 14C-tripalmitin test seems less helpful in the diagnosis of fat malabsorption. A 14C-aminopyrine breath test may turn out to be a simple and valuable liver function test. Oral loading tests with breath analysis of H2 have shown to be helpful in the diagnosis of carbohydrate malabsorption, determination of intestinal transit time and intestinal gas production. Due to technical reasons (gas-chromatographie analysis) H2-breath analysis is still limited to research centers. Despite low radiation doses after oral administration of 14C-labelled compounds oral loading tests with H2- or 13C-analysis might be preferable in the future.

  8. Sleep disordered breathing in pregnancy

    Directory of Open Access Journals (Sweden)

    Bilgay Izci Balserak

    2015-12-01

    Sleep disordered breathing (SDB is very common during pregnancy, and is most likely explained by hormonal, physiological and physical changes. Maternal obesity, one of the major risk factors for SDB, together with physiological changes in pregnancy may predispose women to develop SDB. SDB has been associated with poor maternal and fetal outcomes. Thus, early identification, diagnosis and treatment of SDB are important in pregnancy. This article reviews the pregnancy-related changes affecting the severity of SDB, the epidemiology and the risk factors of SDB in pregnancy, the association of SDB with adverse pregnancy outcomes, and screening and management options specific for this population.

  9. 42 CFR 84.79 - Breathing gas; minimum requirements.

    Science.gov (United States)

    2010-10-01

    ... 42 Public Health 1 2010-10-01 2010-10-01 false Breathing gas; minimum requirements. 84.79 Section...-Contained Breathing Apparatus § 84.79 Breathing gas; minimum requirements. (a) Breathing gas used to supply... respiratory tract irritating compounds. (c) Compressed, gaseous breathing air shall meet the...

  10. 42 CFR 84.72 - Breathing tubes; minimum requirements.

    Science.gov (United States)

    2010-10-01

    ... 42 Public Health 1 2010-10-01 2010-10-01 false Breathing tubes; minimum requirements. 84.72...-Contained Breathing Apparatus § 84.72 Breathing tubes; minimum requirements. Flexible breathing tubes used in conjunction with breathing apparatus shall be designed and constructed to prevent: (a)...

  11. 42 CFR 84.85 - Breathing bags; minimum requirements.

    Science.gov (United States)

    2010-10-01

    ... 42 Public Health 1 2010-10-01 2010-10-01 false Breathing bags; minimum requirements. 84.85 Section...-Contained Breathing Apparatus § 84.85 Breathing bags; minimum requirements. (a) Breathing bags shall have.... (b) Breathing bags shall be constructed of materials which are flexible and resistant to...

  12. News from the Breath Analysis Summit 2011.

    Science.gov (United States)

    Corradi, Massimo; Mutti, Antonio

    2012-06-01

    This special section highlights some of the important work presented at the Breath Analysis Summit 2011, which was held in Parma (Italy) from 11 to 14 September 2011. The meeting, which was jointly organized by the International Association for Breath Research and the University of Parma, was attended by more than 250 delegates from 33 countries, and offered 34 invited lectures and 64 unsolicited scientific contributions. The summit was organized to provide a forum to scientists, engineers and clinicians to present their latest findings and to meet industry executives and entrepreneurs to discuss key trends, future directions and technologies available for breath analysis. A major focus was on nitric oxide, exhaled breath condensate, electronic nose, mass spectrometry and newer sensor technologies. Medical applications ranged from asthma and other respiratory diseases to gastrointestinal disease, occupational diseases, critical care and cancer. Most people identify breath tests with breathalysers used by police to estimate ethanol concentration in blood. However, breath testing has far more sophisticated applications. Breath analysis is rapidly evolving as a new frontier in medical testing for disease states in the lung and beyond. Every individual has a breath fingerprint-or 'breathprint'-that can provide useful information about his or her state of health. This breathprint comprises the many thousands of molecules that are expelled with each breath we exhale. Breath research in the past few years has uncovered the scientific and molecular basis for such clinical observations. Relying on mass spectrometry, we have been able to identify many such unique substances in exhaled breath, including gases, such as nitric oxide (NO) and carbon monoxide (CO), and a wide array of volatile organic compounds. Exhaled breath also carries aerosolized droplets that can be collected as an exhaled breath condensate that contains endogenously produced non-volatile compounds. Breath

  13. Stability of urea in solution and pharmaceutical preparations.

    Science.gov (United States)

    Panyachariwat, Nattakan; Steckel, Hartwig

    2014-01-01

    The stability of urea in solution and pharmaceutical preparations was analyzed as a function of temperature (25°-60°C), pH (3.11-9.67), and initial urea concentration (2.5%-20%). This study was undertaken to (i) obtain more extensive, quantitative information relative to the degradation of urea in both aqueous and non-aqueous solutions and in pharmaceutical preparations, and (ii) test the effects of initial urea concentration, pH, buffer, and temperature values on urea degradation. The stability analysis shows that urea is more stable at the pH range of 4-8 and the stability of urea decreases by increase in temperature for all pH values. Within the experimental range of temperature and initial urea concentration values, the lowest urea degradation was found with lactate buffer pH 6.0. The urea decomposition rate in solution and pharmaceutical preparations shows the dependence of the initial urea concentrations. At higher initial urea concentrations, the rate of degradation is a decreasing function with time. This suggests that the reverse reaction is a factor in the degradation of concentrated urea solution. For non-aqueous solvents, isopropanol showed the best effort in retarding the decomposition of urea. Since the losses in urea is directly influenced by its stability at a given temperature and pH, the stability analysis of urea by the proposed model can be used to prevent the loss and optimize the operating condition for urea-containing pharmaceutical preparations.

  14. Protective supplied breathing air garment

    Science.gov (United States)

    Childers, Edward L.; von Hortenau, Erik F.

    1984-07-10

    A breathing air garment for isolating a wearer from hostile environments containing toxins or irritants includes a suit and a separate head protective enclosure or hood engaging a suit collar in sealing attachment. The hood and suit collar are cylindrically shaped and dimensioned to enable the wearer to withdraw his hands from the suit sleeves to perform manual tasks within the hood interior. Breathing air is supplied from an external air line with an air delivery hose attached to the hood interior. The hose feeds air into an annular halo-like fiber-filled plenum having spaced discharge orifices attached to the hood top wall. A plurality of air exhaust/check valves located at the suit extremities cooperate with the hood air delivery system to provide a cooling flow of circulating air from the hood throughout the suit interior. A suit entry seal provided on the suit rear torso panel permits access into the suit and is sealed with an adhesive sealing flap.

  15. Urea Decomposition Method to Synthesize Hydrotalcites

    Institute of Scientific and Technical Information of China (English)

    Piao Ping YANG; Jian Feng YU; Tong Hao WU; Guo Zong LIU; Tae Sun CHANG; Dong Koo LEE; Deug Hee CHO

    2004-01-01

    The urea decomposition property at high temperature has been used to control the pH value in the synthesis of layer compounds. The hydrotalcites of Mg-Al and Ni-Al with high crystallinity were synthesized by using this property.

  16. Facile Synthesis of Ureas in Ionic Liquid

    Institute of Scientific and Technical Information of China (English)

    Wei Xing QIAN; Feng Yang JU; Yong Min ZHANG; Wei Liang BAO

    2004-01-01

    The reaction of isocyanates with aliphatic and aromatic amines in the 1-n-butyl-3- methylimidazolium tetrafluoroborate (bmimBF4) ionic liquid in good to excellent yields is described. Due to its insolubility, the desired urea solids could be recovered by simple filtration from the ionic liquid after reaction.

  17. Submarines, spacecraft and exhaled breath.

    Science.gov (United States)

    Pleil, Joachim D; Hansel, Armin

    2012-03-01

    Foreword The International Association of Breath Research (IABR) meetings are an eclectic gathering of researchers in the medical, environmental and instrumentation fields; our focus is on human health as assessed by the measurement and interpretation of trace chemicals in human exhaled breath. What may have escaped our notice is a complementary field of research that explores the creation and maintenance of artificial atmospheres practised by the submarine air monitoring and air purification (SAMAP) community. SAMAP is comprised of manufacturers, researchers and medical professionals dealing with the engineering and instrumentation to support human life in submarines and spacecraft (including shuttlecraft and manned rockets, high-altitude aircraft, and the International Space Station (ISS)). Here, the immediate concerns are short-term survival and long-term health in fairly confined environments where one cannot simply 'open the window' for fresh air. As such, one of the main concerns is air monitoring and the main sources of contamination are CO(2) and other constituents of human exhaled breath. Since the inaugural meeting in 1994 in Adelaide, Australia, SAMAP meetings have been held every two or three years alternating between the North American and European continents. The meetings are organized by Dr Wally Mazurek (a member of IABR) of the Defense Systems Technology Organization (DSTO) of Australia, and individual meetings are co-hosted by the navies of the countries in which they are held. An overriding focus at SAMAP is life support (oxygen availability and carbon dioxide removal). Certainly, other air constituents are also important; for example, the closed environment of a submarine or the ISS can build up contaminants from consumer products, cooking, refrigeration, accidental fires, propulsion and atmosphere maintenance. However, the most immediate concern is sustaining human metabolism: removing exhaled CO(2) and replacing metabolized O(2). Another

  18. Urea retranslocation from senescing Arabidopsis leaves is promoted by DUR3-mediated urea retrieval from leaf apoplast.

    Science.gov (United States)

    Bohner, Anne; Kojima, Soichi; Hajirezaei, Mohammad; Melzer, Michael; von Wirén, Nicolaus

    2015-02-01

    In plants, urea derives either from root uptake or protein degradation. Although large quantities of urea are released during senescence, urea is mainly seen as a short-lived nitrogen (N) catabolite serving urease-mediated hydrolysis to ammonium. Here, we investigated the roles of DUR3 and of urea in N remobilization. During natural leaf senescence urea concentrations and DUR3 transcript levels showed a parallel increase with senescence markers like ORE1 in a plant age- and leaf age-dependent manner. Deletion of DUR3 decreased urea accumulation in leaves, whereas the fraction of urea lost to the leaf apoplast was enhanced. Under natural and N deficiency-induced senescence DUR3 promoter activity was highest in the vasculature, but was also found in surrounding bundle sheath and mesophyll cells. An analysis of petiole exudates from wild-type leaves revealed that N from urea accounted for >13% of amino acid N. Urea export from senescent leaves further increased in ureG-2 deletion mutants lacking urease activity. In the dur3 ureG double insertion line the absence of DUR3 reduced urea export from leaf petioles. These results indicate that urea can serve as an early metabolic marker for leaf senescence, and that DUR3-mediated urea retrieval contributes to the retranslocation of N from urea during leaf senescence.

  19. 42 CFR 84.141 - Breathing gas; minimum requirements.

    Science.gov (United States)

    2010-10-01

    ... Respirators § 84.141 Breathing gas; minimum requirements. (a) Breathing gas used to supply supplied-air respirators shall be respirable breathing air and contain no less than 19.5 volume-percent of oxygen....

  20. Urea transporters and sweat response to uremia.

    Science.gov (United States)

    Keller, Raymond W; Bailey, James L; Wang, Yanhua; Klein, Janet D; Sands, Jeff M

    2016-06-01

    In humans, urea is excreted in sweat, largely through the eccrine sweat gland. The urea concentration in human sweat is elevated when compared to blood urea nitrogen. The sweat urea nitrogen (UN) of patients with end-stage kidney disease (ESRD) is increased when compared with healthy humans. The ability to produce sweat is maintained in the overwhelming majority of ESRD patients. A comprehensive literature review found no reports of sweat UN neither in healthy rodents nor in rodent models of chronic kidney disease (CKD). Therefore, this study measured sweat UN concentrations in healthy and uremic rats. Uninephrectomy followed by renal artery ligation was used to remove 5/6 of renal function. Rats were then fed a high-protein diet to induce uremia. Pilocarpine was used to induce sweating. Sweat droplets were collected under oil. Sweat UN was measured with a urease assay. Serum UN was measured using a fluorescent ortho-pthalaldehyde reaction. Immunohistochemistry (IHC) was accomplished with a horseradish peroxidase and diaminobenzidine technique. Sweat UN in uremic rats was elevated greater than two times compared to healthy pair-fed controls (220 ± 17 and 91 ± 15 mmol/L, respectively). Post hoc analysis showed a significant difference between male and female uremic sweat UN (279 ± 38 and 177 ± 11 mmol/L, respectively.) IHC shows, for the first time, the presence of the urea transporters UT-B and UT-A2 in both healthy and uremic rat cutaneous structures. Future studies will use this model to elucidate how rat sweat UN and other solute excretion is altered by commonly prescribed diuretics.

  1. How Does a Hopping Kangaroo Breathe?

    Science.gov (United States)

    Giuliodori, Mauricio J.; Lujan, Heidi L.; Janbaih, Hussein; DiCarlo, Stephen E.

    2010-01-01

    We developed a model to demonstrate how a hopping kangaroo breathes. Interestingly, a kangaroo uses less energy to breathe while hopping than while standing still. This occurs, in part, because rather than using muscle power to move air into and out of the lungs, air is pulled into (inspiration) and pushed out of (expiration) the lungs as the…

  2. Controlled Frequency Breathing Reduces Inspiratory Muscle Fatigue.

    Science.gov (United States)

    Burtch, Alex R; Ogle, Ben T; Sims, Patrick A; Harms, Craig A; Symons, Thorburn B; Folz, Rodney J; Zavorsky, Gerald S

    2016-08-16

    Controlled frequency breathing (CFB) is a common swim training modality involving holding one's breath for about 7 to 10 strokes before taking another breath. We sought to examine the effects of CFB training on reducing respiratory muscle fatigue. Competitive college swimmers were randomly divided into either the CFB group that breathed every 7 to 10 strokes, or a control group that breathed every 3-4 strokes. Twenty swimmers completed the study. The training intervention included 5-6 weeks (16 sessions) of 12x50-m repetitions with breathing 8-10 breaths per 50m (control group), or 2-3 breaths per 50-m (CFB group). Inspiratory muscle fatigue was defined as the decrease in maximal inspiratory mouth-pressure (MIP) between rest and 46s after a 200 yard free-style swimming race [115s (SD 7)]. Aerobic capacity, pulmonary diffusing capacity, and running economy were also measured pre and post-training. Pooled results demonstrated a 12% decrease in MIP at 46s post-race [-15 (SD 14) cm H2O, Effect size = -0.48, p training, only the CFB group prevented a decline in MIP values pre to 46 s post-race [-2 (13) cm H2O, p > 0.05]. However, swimming performance, aerobic capacity, pulmonary diffusing capacity, and running economy did not improve (p > 0.05) post-training in either group. In conclusion, CFB training appears to prevent inspiratory muscle fatigue yet no difference was found in performance outcomes.

  3. Relationships between hippocampal activity and breathing patterns

    DEFF Research Database (Denmark)

    Harper, R M; Poe, G R; Rector, D M;

    1998-01-01

    Single cell discharge, EEG activity, and optical changes accompanying alterations in breathing patterns, as well as the knowledge that respiratory musculature is heavily involved in movement and other behavioral acts, implicate hippocampal regions in some aspects of breathing control. The control...

  4. 76 FR 15339 - Solid Urea From Russia and Ukraine

    Science.gov (United States)

    2011-03-21

    ... COMMISSION Solid Urea From Russia and Ukraine AGENCY: United States International Trade Commission. ACTION... orders on solid urea from Russia and Ukraine. SUMMARY: The Commission hereby gives notice that it will...)) to determine whether revocation of the antidumping duty orders on solid urea from Russia and...

  5. Synthesis and Bioactivity of Novel Fluorinated Heteroaromatic Ureas

    Institute of Scientific and Technical Information of China (English)

    Xin Jian SONG; Xiao Hong TAN; Yan Gang WANG

    2006-01-01

    In order to find new urea cytokinins, a series of novel fluorinated heteroaromatic ureas have been designed and synthesized. The crystal structure of 3g was further determined by single crystal X-ray diffraction to obtain the structural feature of this class of urea compounds. The preliminary bioassay showed that some title compounds have good cytokinin activity.

  6. 75 FR 74746 - Solid Urea From Russia and Ukraine

    Science.gov (United States)

    2010-12-01

    ... COMMISSION Solid Urea From Russia and Ukraine AGENCY: United States International Trade Commission. ACTION: Institution of five-year reviews concerning the antidumping duty orders on solid urea from Russia and Ukraine... antidumping duty orders on solid urea from Russia and Ukraine would be likely to lead to continuation...

  7. 76 FR 77015 - Solid Urea From Russia and Ukraine

    Science.gov (United States)

    2011-12-09

    ... COMMISSION Solid Urea From Russia and Ukraine Determination On the basis of the record \\1\\ developed in the... antidumping duty orders on solid urea from Russia and Ukraine would be likely to lead to continuation or... 2011), entitled Solid Urea from Russia and Ukraine: Investigation Nos. 731-TA- 340-E and 340-H...

  8. 21 CFR 176.320 - Sodium nitrate-urea complex.

    Science.gov (United States)

    2010-04-01

    ... 21 Food and Drugs 3 2010-04-01 2009-04-01 true Sodium nitrate-urea complex. 176.320 Section 176... Substances for Use Only as Components of Paper and Paperboard § 176.320 Sodium nitrate-urea complex. Sodium nitrate-urea complex may be safely used as a component of articles intended for use in...

  9. Pulse pressure variation to predict fluid responsiveness in spontaneously breathing patients: tidal vs. forced inspiratory breathing.

    Science.gov (United States)

    Hong, D M; Lee, J M; Seo, J H; Min, J J; Jeon, Y; Bahk, J H

    2014-07-01

    We evaluated whether pulse pressure variation can predict fluid responsiveness in spontaneously breathing patients. Fifty-nine elective thoracic surgical patients were studied before induction of general anaesthesia. After volume expansion with hydroxyethyl starch 6 ml.kg(-1) , patients were defined as responders by a ≥ 15% increase in the cardiac index. Haemodynamic variables were measured before and after volume expansion and pulse pressure variations were calculated during tidal breathing and during forced inspiratory breathing. Median (IQR [range]) pulse pressure variation during forced inspiratory breathing was significantly higher in responders (n = 29) than in non-responders (n = 30) before volume expansion (18.2 (IQR 14.7-18.2 [9.3-31.3])% vs. 10.1 (IQR 8.3-12.6 [4.8-21.1])%, respectively, p breathing could predict fluid responsiveness (area under the curve 0.910, p breathing can be used to guide fluid management in spontaneously breathing patients.

  10. Discriminating between Nasal and Mouth Breathing

    CERN Document Server

    Curran, Kevin; Coyle, Damian

    2010-01-01

    The recommendation to change breathing patterns from the mouth to the nose can have a significantly positive impact upon the general well being of the individual. We classify nasal and mouth breathing by using an acoustic sensor and intelligent signal processing techniques. The overall purpose is to investigate the possibility of identifying the differences in patterns between nasal and mouth breathing in order to integrate this information into a decision support system which will form the basis of a patient monitoring and motivational feedback system to recommend the change from mouth to nasal breathing. Our findings show that the breath pattern can be discriminated in certain places of the body both by visual spectrum analysis and with a Back Propagation neural network classifier. The sound file recoded from the sensor placed on the hollow in the neck shows the most promising accuracy which is as high as 90%.

  11. Abortion--the breath of life.

    Science.gov (United States)

    Joling, R J

    1974-01-01

    A scholarly review of medical-legal and biblical authority on the su bject of abortion supports abortion as a woman's right when it is performed before the fetus has had its "breath of life." Based on biblical evidence, a person becomes a living being when the soul, the "breath of life" is breathed into it. Without the "breath of life" no person exists. A fetus less than 28 weeks old is incapable of breathing alone; thus an aborted fetus that age is not truly a living human being capable of surviving independently of its mother's womb. Legal aspects include supreme, local and state court decisions defining abortion. It is ultimately expected that each person will determine what approach to take towards the abortion question. Abortion is still a personal problem regardless of supreme court decisions or ecclesiastical determinants. Religion and moral concepts should be the guiding conscience involved in the question of abortion.

  12. Rapid eye movement sleep in breath holders.

    Science.gov (United States)

    Kohyama, J; Hasegawa, T; Shimohira, M; Fukumizu, M; Iwakawa, Y

    2000-07-01

    One-night polysomnography was performed on seven subjects suffering from breath-holding spells, including one whose death was suggested to be a consequence of a breath-holding spell. The fatal case showed no rapid eye movements (REMs) during REM sleep, although he exhibited REMs during wakefulness. The average numbers of both REMs and bursts of REMs in REM sleep in the other six breath holders were significantly lower than those in age-matched controls. The breath holders showed no airway obstruction, desaturation, or sleep fragmentation. Since the rapid ocular activity in REM sleep is generated in the brain stem, we hypothesized that a functional brainstem disturbance is involved in the occurrence of breath-holding spells.

  13. Biobased carbon content of resin extracted from polyethylene composite by carbon-14 concentration measurements using accelerator mass spectrometry.

    Science.gov (United States)

    Taguchi, Kazuhiro; Kunioka, Masao; Funabashi, Masahiro; Ninomiya, Fumi

    2014-01-01

    An estimation procedure for biobased carbon content of polyethylene composite was studied using carbon-14 ((14)C) concentration ratios as measured by accelerated mass spectrometry (AMS). Prior to the measurement, additives and fillers in composites should be removed because they often contain a large amount of biobased carbon and may shift the estimation. Samples of resin with purity suitable for measurement were isolated from composites with a Soxhlet extractor using heated cyclohexanone. After cooling of extraction solutions, the resin was recovered as a fine semi-crystalline precipitate, which was easily filtered. Recovery rates were almost identical (99%), even for low-density polyethylene and linear low-density polyethylene, which may have lower crystallinity. This procedure could provide a suitable approach for estimation of biobased carbon content by AMS on the basis of the standard ASTM D 6866. The biobased carbon content for resin extracted from polyethylene composites allow for the calculation of biosynthetic polymer content, which is an indicator of mass percentage of the biobased plastic resin in the composite.

  14. Time Breath of Psychological Theories

    DEFF Research Database (Denmark)

    Tateo, Luca; Valsiner, Jaan

    2015-01-01

    Psychology as a self-aspiring, ambitious, developmental science faces the crucial limit of time—both theoretically and practically. The issue of time in constructing psychology’s theories is a major unresolved metatheoretical task. This raises several questions about generalization of knowledge......: which is the time length of breath of psychological theories? Which is the temporal dimension of psychological processes? In this article we discuss the role of different axiomatic assumptions about time in the construction of psychological theories. How could different theories include a concept...... of time—or fail to do that? How can they generalize with respect to time? The different conceptions of time often remain implicit, while shaping the concepts used in understanding psychological processes. Any preconception about time in human development will foster the generalizability of theory, as well...

  15. Reconsidering the Lack of Urea Toxicity in Dialysis Patients.

    Science.gov (United States)

    Massy, Ziad A; Pietrement, Christine; Touré, Fatouma

    2016-09-01

    Urea is an old uremic toxin which has been used for many years as a global biomarker of CKD severity and dialysis adequacy. Old studies were not in favor of its role as a causal factor in the pathogenesis of complications associated with the uremic state. However, recent experimental and clinical evidence is compatible with both direct and indirect toxicity of urea, particularly via the deleterious actions of urea-derived carbamylated molecules. Further studies are clearly needed to explore the potential relevance of urea-related CKD complications for patient management, in particular the place of new therapeutic strategies to prevent urea toxicity.

  16. Synthesis and quality control of {sup 13}C-enriched urea for Helicobacter pylori (HP) diagnosis

    Energy Technology Data Exchange (ETDEWEB)

    Sant Ana Filho, Carlos R.; Tavares, Claudineia R.O.; Ferreira, Andre V.; Prestes, Cleber V.; Bendassolli, Jose A., E-mail: jab@cena.usp.br [Centro de Energia Nuclear na Agricultura (CENA/USP), Piracicaba, SP (Brazil)

    2013-08-01

    The aim of the study was to synthesize the urea ({sup 13}CO(NH{sub 2}){sub 2}), with 99% {sup 13}C atoms, and to perform a quality analysis for the diagnosis (breath test) of Helicobacter pylori. Furthermore, the process was submitted to economic analysis. The reaction was performed in a stainless steel reactor, lined with polytetrafluoroethylene, under low pressure and temperature. The synthesis method was shown to be appropriate (2.35 g; 81.9% yield), evidenced by physico-chemical and microbiological results, according to Brazilian legislation. The production and diagnosis costs were competitive compared with national and international market values, rendering this a valuable tool in clinical medicine. (author)

  17. Use of a least absolute shrinkage and selection operator (LASSO) model to selected ion flow tube mass spectrometry (SIFT-MS) analysis of exhaled breath to predict the efficacy of dialysis: a pilot study.

    Science.gov (United States)

    Wang, Maggie Haitian; Chong, Ka Chun; Storer, Malina; Pickering, John W; Endre, Zoltan H; Lau, Steven Yf; Kwok, Chloe; Lai, Maria; Chung, Hau Yin; Ying Zee, Benny Chung

    2016-09-28

    Selected ion flow tube-mass spectrometry (SIFT-MS) provides rapid, non-invasive measurements of a full-mass scan of volatile compounds in exhaled breath. Although various studies have suggested that breath metabolites may be indicators of human disease status, many of these studies have included few breath samples and large numbers of compounds, limiting their power to detect significant metabolites. This study employed a least absolute shrinkage and selective operator (LASSO) approach to SIFT-MS data of breath samples to preliminarily evaluate the ability of exhaled breath findings to monitor the efficacy of dialysis in hemodialysis patients. A process of model building and validation showed that blood creatinine and urea concentrations could be accurately predicted by LASSO-selected masses. Using various precursors, the LASSO models were able to predict creatinine and urea concentrations with high adjusted R-square (>80%) values. The correlation between actual concentrations and concentrations predicted by the LASSO model (using precursor H3O(+)) was high (Pearson correlation coefficient  =  0.96). Moreover, use of full mass scan data provided a better prediction than compounds from selected ion mode. These findings warrant further investigations in larger patient cohorts. By employing a more powerful statistical approach to predict disease outcomes, breath analysis using SIFT-MS technology could be applicable in future to daily medical diagnoses.

  18. Application of LaserBreath-001 for breath acetone measurement in subjects with diabetes mellitus

    Science.gov (United States)

    Wang, Zhennan; Sun, Meixiu; Chen, Zhuying; Zhao, Xiaomeng; Li, Yingxin; Wang, Chuji

    2016-11-01

    Breath acetone is a promising biomarker of diabetes mellitus. With an integrated standalone, on-site cavity ringdown breath acetone analyzer, LaserBreath-001, we tested breath samples from 23 type 1 diabetic (T1D) patients, 312 type 2 diabetic (T2D) patients, 52 healthy subjects. In the cross-sectional studies, the obtained breath acetone concentrations were higher in the diabetic subjects compared with those in the control group. No correlation between breath acetone and simultaneous BG was observed in the T1D, T2D, and healthy subjects. A moderate positive correlation between the mean individual breath acetone concentrations and the mean individual BG levels was observed in the 20 T1D patients without ketoacidosis. In a longitudinal study, the breath acetone concentrations in a T1D patient with ketoacidosis decreased significantly and remained stable during the 5-day hospitalization. The results from a relatively large number of subjects tested indicate that an elevated mean breath acetone concentration exists in diabetic patients in general. Although many physiological parameters affect breath acetone concentrations, fast (diabetic screening and management under a specifically controlled condition.

  19. An Ultrasonic Contactless Sensor for Breathing Monitoring

    Directory of Open Access Journals (Sweden)

    Philippe Arlotto

    2014-08-01

    Full Text Available The monitoring of human breathing activity during a long period has multiple fundamental applications in medicine. In breathing sleep disorders such as apnea, the diagnosis is based on events during which the person stops breathing for several periods during sleep. In polysomnography, the standard for sleep disordered breathing analysis, chest movement and airflow are used to monitor the respiratory activity. However, this method has serious drawbacks. Indeed, as the subject should sleep overnight in a laboratory and because of sensors being in direct contact with him, artifacts modifying sleep quality are often observed. This work investigates an analysis of the viability of an ultrasonic device to quantify the breathing activity, without contact and without any perception by the subject. Based on a low power ultrasonic active source and transducer, the device measures the frequency shift produced by the velocity difference between the exhaled air flow and the ambient environment, i.e., the Doppler effect. After acquisition and digitization, a specific signal processing is applied to separate the effects of breath from those due to subject movements from the Doppler signal. The distance between the source and the sensor, about 50 cm, and the use of ultrasound frequency well above audible frequencies, 40 kHz, allow monitoring the breathing activity without any perception by the subject, and therefore without any modification of the sleep quality which is very important for sleep disorders diagnostic applications. This work is patented (patent pending 2013-7-31 number FR.13/57569.

  20. Decreased chewing activity during mouth breathing.

    Science.gov (United States)

    Hsu, H-Y; Yamaguchi, K

    2012-08-01

    This study examined the effect of mouth breathing on the strength and duration of vertical effect on the posterior teeth using related functional parameters during 3 min of gum chewing in 39 nasal breathers. A CO(2) sensor was placed over the mouth to detect expiratory airflow. When no airflow was detected from the mouth throughout the recording period, the subject was considered a nasal breather and enrolled in the study. Electromyographic (EMG) activity was recorded during 3 min of gum chewing. The protocol was repeated with the nostrils occluded. The strength of the vertical effect was obtained as integrated masseter muscle EMG activity, and the duration of vertical effect was also obtained as chewing stroke count, chewing cycle variation and EMG activity duration above baseline. Baseline activity was obtained from the isotonic EMG activity during jaw movement at 1.6 Hz without making tooth contact. The duration represented the percentage of the active period above baseline relative to the 3-min chewing period. Paired t-test and repeated analysis of variance were used to compare variables between nasal and mouth breathing. The integrated EMG activity and the duration of EMG activity above baseline, chewing stroke count and chewing cycle significantly decreased during mouth breathing compared with nasal breathing (Pmouth breathing was significantly greater than nasal breathing (PMouth breathing reduces the vertical effect on the posterior teeth, which can affect the vertical position of posterior teeth negatively, leading to malocclusion.

  1. An ultrasonic contactless sensor for breathing monitoring.

    Science.gov (United States)

    Arlotto, Philippe; Grimaldi, Michel; Naeck, Roomila; Ginoux, Jean-Marc

    2014-08-20

    The monitoring of human breathing activity during a long period has multiple fundamental applications in medicine. In breathing sleep disorders such as apnea, the diagnosis is based on events during which the person stops breathing for several periods during sleep. In polysomnography, the standard for sleep disordered breathing analysis, chest movement and airflow are used to monitor the respiratory activity. However, this method has serious drawbacks. Indeed, as the subject should sleep overnight in a laboratory and because of sensors being in direct contact with him, artifacts modifying sleep quality are often observed. This work investigates an analysis of the viability of an ultrasonic device to quantify the breathing activity, without contact and without any perception by the subject. Based on a low power ultrasonic active source and transducer, the device measures the frequency shift produced by the velocity difference between the exhaled air flow and the ambient environment, i.e., the Doppler effect. After acquisition and digitization, a specific signal processing is applied to separate the effects of breath from those due to subject movements from the Doppler signal. The distance between the source and the sensor, about 50 cm, and the use of ultrasound frequency well above audible frequencies, 40 kHz, allow monitoring the breathing activity without any perception by the subject, and therefore without any modification of the sleep quality which is very important for sleep disorders diagnostic applications. This work is patented (patent pending 2013-7-31 number FR.13/57569).

  2. Breathing and sleep at high altitude.

    Science.gov (United States)

    Ainslie, Philip N; Lucas, Samuel J E; Burgess, Keith R

    2013-09-15

    We provide an updated review on the current understanding of breathing and sleep at high altitude in humans. We conclude that: (1) progressive changes in pH initiated by the respiratory alkalosis do not underlie early (48 h), complex cellular and neurochemical re-organization occurs both in the peripheral chemoreceptors as well as within the central nervous system. The latter is likely influenced by central acid-base changes secondary to the extent of the initial respiratory responses to initial exposure to high altitude; (3) sleep at high altitude is disturbed by various factors, but principally by periodic breathing; (4) the extent of periodic breathing during sleep at altitude intensifies with duration and severity of exposure; (5) complex interactions between hypoxic-induced enhancement in peripheral and central chemoreflexes and cerebral blood flow--leading to higher loop gain and breathing instability--underpin this development of periodic breathing during sleep; (6) because periodic breathing may elevate rather than reduce mean SaO2 during sleep, this may represent an adaptive rather than maladaptive response; (7) although oral acetazolamide is an effective means to reduce periodic breathing by 50-80%, recent studies using positive airway pressure devices to increase dead space, hyponotics and theophylline are emerging but appear less practical and effective compared to acetazolamide. Finally, we suggest avenues for future research, and discuss implications for understanding sleep pathology.

  3. Milk Urea Dynamics during its Transformation into Yogurt

    Directory of Open Access Journals (Sweden)

    Cornelia Vintila

    2011-10-01

    Full Text Available The purpose of our work was to evaluate in what measure milk urea concentration stays in processed yogurt and in what measure urea dose influences its quality. We added known amounts of urea into milk destined to yogurt processing in order to obtain probes with concentrations from 0,5 to 28 mg/ 100 ml milk. Obtained results lead us to the conclusion that milk urea decreases dramatically until the finishing of the process of milk coagulation and its transformation into yogurt. All probes which contained higher amounts of urea than 6 mg/ 100 ml milk, urea totally disappeared from yogurt before 48 hours of keeping. Milk coagulation time and its transformation to yogurt is reduced proportional with urea concentration in milk.

  4. Determination of urea kinetics by isotope dilution with [C-13]urea and gas chromatography isotope ratio mass spectrometry (GC-IRMS) analysis

    NARCIS (Netherlands)

    Kloppenburg, Wybe; Wolthers, BG; Stellaard, F; Elzinga, H; Tepper, T; deJong, PE; Huisman, RM

    1997-01-01

    1. Stable urea isotopes can be used to study urea kinetics in humans, The use of stable urea isotopes far studying urea kinetic parameters in humans on a large scale is hampered by the high costs of the labelled material, We devised a urea dilution for measurement of the distribution volume, product

  5. Ammonia and urea permeability of mammalian aquaporins

    DEFF Research Database (Denmark)

    Litman, Thomas; Søgaard, Rikke; Zeuthen, Thomas

    2009-01-01

    The human aquaporins,AQP3,AQP7, AQP8,AQP9, and possibly AQP10, are permeable to ammonia, and AQP7, AQP9, and possibly AQP3, are permeable to urea. In humans, these aquaporins supplement the ammonia transport of the Rhesus (Rh) proteins and the urea transporters (UTs). The mechanism by which...... ammonium is transported by aquaporins is not fully resolved. A comparison of transport equations, models, and experimental data shows that ammonia is transported in its neutral form, NH(3). In the presence of NH(3), the aquaporin stimulates H(+) transport. Consequently, this transport of H(+) is only...... significant at alkaline pH. It is debated whether the H(+) ion passes via the aquaporin or by some external route; the investigation of this problem requires the aquaporin-expressing cell to be voltage-clamped. The ammonia-permeable aquaporins differ from other aquaporins by having a less restrictive aromatic...

  6. Quantum crystallographic charge density of urea

    OpenAIRE

    Wall, Michael E.

    2015-01-01

    Standard X-ray crystallography methods use free-atom models to calculate mean unit-cell charge densities. Real molecules, however, have shared charge that is not captured accurately using free-atom models. To address this limitation, a charge density model of crystalline urea was calculated using high-level quantum theory and was refined against publicly available ultra-high-resolution experimental Bragg data, including the effects of atomic displacement parameters. The resulting quantum crys...

  7. Analysis of urea distribution volume in hemodialysis.

    Science.gov (United States)

    Maduell, F; Sigüenza, F; Caridad, A; Miralles, F; Serrato, F

    1994-01-01

    According to the urea kinetic model it is considered that the urea distribution volume (V) is that of body water, and that it is distributed in only one compartment. Since the V value is different to measure, it is normal to use 58% of body weight, in spite of the fact that it may range from 35 to 75%. In this study, we have calculated the value of V by using an accurate method based on the total elimination of urea from the dialysate. We have studied the V, and also whether the different dialysis characteristics modify it. Thirty-five patients were included in this study, 19 men and 16 women, under a chronic hemodialysis programme. The dialysate was collected in a graduated tank, and the concentration of urea in plasma and in dialysate were determined every hour. Every patient received six dialysis sessions, changing the blood flow (250 or 350 ml/min), the ultrafiltration (0.5 or 1.5 l/h), membrane (cuprophane or polyacrylonitrile) and/or buffer (bicarbonate or acetate). At the end of the hemodialysis session, the V value ranged from 43 to 72% of body weight; nevertheless, this value was practically constant in every patient. The V value gradually increased throughout the dialysis session, 42.1 +/- 6.9% of body weight in the first hour, 50.7 +/- 7.5% in the second hour and 55.7 +/- 7.9% at the end of the dialysis session. The change of blood flow, ultrafiltration, membrane or buffer did not alter the results. The V value was significantly higher in men in comparison with women, 60.0 +/- 6.6% vs. 50.5 +/- 5.9% of body weight (p < 0.001).

  8. Urea Induced Denaturation of Pre-Q1 Riboswitch

    Science.gov (United States)

    Yoon, Jeseong; Thirumalai, Devarajan; Hyeon, Changbong

    2013-01-01

    Urea, a polar molecule with a large dipole moment, not only destabilizes the folded RNA structures, but can also enhance the folding rates of large ribozymes. Unlike the mechanism of urea-induced unfolding of proteins, which is well understood, the action of urea on RNA has barely been explored. We performed extensive all atom molecular dynamics (MD) simulations to determine the molecular underpinnings of urea-induced RNA denaturation. Urea displays its denaturing power in both secondary and tertiary motifs of the riboswitch (RS) structure. Our simulations reveal that the denaturation of RNA structures is mainly driven by the hydrogen bonds and stacking interactions of urea with the bases. Through detailed studies of the simulation trajectories, we found that geminate pairs between urea and bases due to hydrogen bonds and stacks persist only ~ (0.1-1) ns, which suggests that urea-base interaction is highly dynamic. Most importantly, the early stage of base pair disruption is triggered by penetration of water molecules into the hydrophobic domain between the RNA bases. The infiltration of water into the narrow space between base pairs is critical in increasing the accessibility of urea to transiently disrupted bases, thus allowing urea to displace inter base hydrogen bonds. This mechanism, water-induced disruption of base-pairs resulting in the formation of a "wet" destabilized RNA followed by solvation by urea, is the exact opposite of the two-stage denaturation of proteins by urea. In the latter case, initial urea penetration creates a dry-globule, which is subsequently solvated by water penetration leading to global protein unfolding. Our work shows that the ability to interact with both water and polar, non-polar components of nucleotides makes urea a powerful chemical denaturant for nucleic acids.

  9. The application of carbon-14 analyses to the source apportionment of atmospheric carbonaceous particulate matter: a review.

    Science.gov (United States)

    Heal, Mathew R

    2014-01-01

    Organic carbon (OC) and elemental carbon (EC) together constitute a substantial proportion of airborne particulate matter (PM). Insight into the sources of this major contributor to PM is important for policies to mitigate the impact of PM on human health and climate change. In recent years measurement of the abundance of the radioisotope of carbon ((14)C) in samples of PM by accelerator mass spectrometry has been used to help quantify the relative contributions from sources of fossil carbon and contemporary carbon. This review provides an introduction to the different sources of carbon within PM and the role of (14)C measurements, a description of the preparation of PM samples and of the instrumentation used to quantify (14)C, and a summary of the results and source apportionment methods reported in published studies since 2004. All studies report a sizable fraction of the carbonaceous PM as of non-fossil origin. Even for PM collected in urban locations, the proportions of non-fossil carbon generally exceed 30%; typically the proportion in urban background locations is around 40-60% depending on the local influence of biomass burning. Where values have been measured directly, proportions of non-fossil carbon in EC are lower than in OC, reflecting the greater contribution of fossil-fuel combustion to EC and the generally small sources of contemporary EC. Detailed source apportionment studies point to important contributions from biogenic-derived secondary OC, consistent with other evidence of a ubiquitous presence of heavily oxidized background secondary OC. The review concludes with some comments on current issues and future prospects, including progress towards compound-class and individual-compound-specific (14)C analyses.

  10. Role of ureogenesis in tackling problems of ammonia toxicity during exposure to higher ambient ammonia in the air-breathing walking catfish Clarias batrachus

    Indian Academy of Sciences (India)

    Nirmalendu Saha; Shritapa Datta; Kuheli Biswas; Zaiba Y Kharbuli

    2003-12-01

    In the present study, the possible role of ureogenesis to avoid the accumulation of toxic ammonia to a lethal level under hyper-ammonia stress was tested in the air-breathing walking catfish Clarias batrachus by exposing the fish at 25 mM NH4Cl for 7 days. Excretion of ammonia by the NH4Cl-exposed fish was totally suppressed, which was accompanied by significant accumulation of ammonia in different body tissues. The walking catfish, which is otherwise predominantly ammoniotelic, turned totally towards ureotelism from ammoniotelism with a 5- to 6-fold increase of urea-N excretion during exposure to higher ambient ammonia. Stimulation of ureogenesis was accompanied with significant increase of some of the key urea cycle enzymes such as carbamyl phosphate synthetase (urea cycle-related), argininosuccinate synthetase and argininosuccinate lyase both in hepatic and non-hepatic tissues. Due to this unique physiological strategy of turning towards ureotelism from ammoniotelism via the induced urea cycle, this air-breathing catfish is able to survive in very high ambient ammonia, which they face in certain seasons of the year in the natural habitat.

  11. 46 CFR 197.456 - Breathing supply hoses.

    Science.gov (United States)

    2010-10-01

    ... 46 Shipping 7 2010-10-01 2010-10-01 false Breathing supply hoses. 197.456 Section 197.456 Shipping....456 Breathing supply hoses. (a) The diving supervisor shall insure that— (1) Each breathing supply....5 times its maximum working pressure; (2) Each breathing supply hose assembly, prior to being...

  12. 21 CFR 862.3080 - Breath nitric oxide test system.

    Science.gov (United States)

    2010-04-01

    ... 21 Food and Drugs 8 2010-04-01 2010-04-01 false Breath nitric oxide test system. 862.3080 Section... Systems § 862.3080 Breath nitric oxide test system. (a) Identification. A breath nitric oxide test system is a device intended to measure fractional nitric oxide in human breath. Measurement of changes...

  13. 42 CFR 84.91 - Breathing resistance test; exhalation.

    Science.gov (United States)

    2010-10-01

    ... 42 Public Health 1 2010-10-01 2010-10-01 false Breathing resistance test; exhalation. 84.91...-Contained Breathing Apparatus § 84.91 Breathing resistance test; exhalation. (a) Resistance to exhalation...-circuit apparatus with a breathing machine as described in § 84.88, and the exhalation resistance...

  14. 42 CFR 84.88 - Breathing bag test.

    Science.gov (United States)

    2010-10-01

    ... 42 Public Health 1 2010-10-01 2010-10-01 false Breathing bag test. 84.88 Section 84.88 Public... RESEARCH AND RELATED ACTIVITIES APPROVAL OF RESPIRATORY PROTECTIVE DEVICES Self-Contained Breathing Apparatus § 84.88 Breathing bag test. (a) Breathing bags will be tested in an air atmosphere saturated...

  15. An introduction to the psychophysiology of breathing.

    Science.gov (United States)

    Ley, R

    1994-06-01

    Breathing can be viewed as an independent variable which affects emotion, cognition, and behavior as well as a dependent variable which reflects changes in emotion, cognition, and behavior. This bidirectional interaction is basic to an appreciation of the significance of breathing in terms of its relevance in research and application. The underlying premise of the present article is that since breathing is a behavior that is under voluntary as well as reflexive control, it can be modified according to the principles of both instrumental training (operant conditioning) and Pavlovian (classical) conditioning. The implications of this premise are relevant to theory, diagnosis, and treatment of stress and anxiety-related disorders (e.g., panic disorder, phobias, test anxiety, occupational strain, and related psychosomatic disorders), and to basic and applied research in the psychophysiology of breathing.

  16. Can Breath Test Detect Stomach Cancers Earlier?

    Science.gov (United States)

    ... news/fullstory_163342.html Can Breath Test Detect Stomach Cancers Earlier? New technology may also spot esophageal cancers ... the only way to diagnose esophageal cancer or stomach cancer is with endoscopy. This method is expensive, invasive ...

  17. Breathing exercises for adults with asthma.

    Science.gov (United States)

    2015-11-01

    Asthma is a common long-term condition that remains poorly controlled in many people despite the availability of pharmacological interventions, evidence-based treatment guidelines and care pathways.(1) There is considerable public interest in the use of non-pharmacological approaches for the treatment of asthma.(2) A survey of people with asthma reported that many have used complementary and alternative medicine, often without the knowledge of their clinical team.(3) Such interventions include breathing techniques, herbal products, homeopathy and acupuncture. The role of breathing exercises within the management of asthma has been controversial, partly because early claims of effectiveness were exaggerated.(4) UK national guidance and international guidelines on the management of asthma have included the option of breathing exercise programmes as an adjuvant to pharmacological treatment.(5,6) Here we discuss the types of breathing exercises used and review the evidence for their effectiveness.

  18. Fast and Accurate Exhaled Breath Ammonia Measurement

    OpenAIRE

    Solga, Steven F; Mudalel, Matthew L; Spacek, Lisa A.; Risby, Terence H.

    2014-01-01

    This exhaled breath ammonia method uses a fast and highly sensitive spectroscopic method known as quartz enhanced photoacoustic spectroscopy (QEPAS) that uses a quantum cascade based laser. The monitor is coupled to a sampler that measures mouth pressure and carbon dioxide. The system is temperature controlled and specifically designed to address the reactivity of this compound. The sampler provides immediate feedback to the subject and the technician on the quality of the breath effort. Toge...

  19. Swimming in air-breathing fishes.

    Science.gov (United States)

    Lefevre, S; Domenici, P; McKenzie, D J

    2014-03-01

    Fishes with bimodal respiration differ in the extent of their reliance on air breathing to support aerobic metabolism, which is reflected in their lifestyles and ecologies. Many freshwater species undertake seasonal and reproductive migrations that presumably involve sustained aerobic exercise. In the six species studied to date, aerobic exercise in swim flumes stimulated air-breathing behaviour, and there is evidence that surfacing frequency and oxygen uptake from air show an exponential increase with increasing swimming speed. In some species, this was associated with an increase in the proportion of aerobic metabolism met by aerial respiration, while in others the proportion remained relatively constant. The ecological significance of anaerobic swimming activities, such as sprinting and fast-start manoeuvres during predator-prey interactions, has been little studied in air-breathing fishes. Some species practise air breathing during recovery itself, while others prefer to increase aquatic respiration, possibly to promote branchial ion exchange to restore acid-base balance, and to remain quiescent and avoid being visible to predators. Overall, the diversity of air-breathing fishes is reflected in their swimming physiology as well, and further research is needed to increase the understanding of the differences and the mechanisms through which air breathing is controlled and used during exercise.

  20. Variation of milk urea in dairy cattle : a study on factors that affect the relationship between urea concentration in milk and urea excretion in urine

    NARCIS (Netherlands)

    Spek, J.W.

    2013-01-01

    The aim of this thesis was to increase the applicability of milk urea nitrogen concentration (MUN) as a predictor of urinary urea nitrogen excretion (UUN) by identifying and quantifying factors that can explain variation in MUN that is not related to UUN. A literature study was conducted in order to

  1. Clinical Applications of CO2 and H2 Breath Test

    OpenAIRE

    ZHAO Si-qian; Chen, Bao-Jun; LUO Zhi-fu

    2016-01-01

    Breath test is non-invasive, high sensitivity and high specificity. In this article, CO2 breath test, H2 breath test and their clinical applications were elaborated. The main applications of CO2 breath test include helicobacter pylori test, liver function detection, gastric emptying test, insulin resistance test, pancreatic exocrine secretion test, etc. H2 breath test can be applied in the diagnosis of lactose malabsorption and detecting small intestinal bacterial overgrowth. With further res...

  2. Mathematical modeling of urea transport in the kidney.

    Science.gov (United States)

    Layton, Anita T

    2014-01-01

    Mathematical modeling techniques have been useful in providing insights into biological systems, including the kidney. This article considers some of the mathematical models that concern urea transport in the kidney. Modeling simulations have been conducted to investigate, in the context of urea cycling and urine concentration, the effects of hypothetical active urea secretion into pars recta. Simulation results suggest that active urea secretion induces a "urea-selective" improvement in urine concentrating ability. Mathematical models have also been built to study the implications of the highly structured organization of tubules and vessels in the renal medulla on urea sequestration and cycling. The goal of this article is to show how physiological problems can be formulated and studied mathematically, and how such models may provide insights into renal functions.

  3. Final report of the safety assessment of Urea.

    Science.gov (United States)

    2005-01-01

    Although Urea is officially described as a buffering agent, humectant, and skin-conditioning agent-humectant for use in cosmetic products, there is a report stating that Urea also is used in cosmetics for its desquamating and antimicrobial action. In 2001, the Food and Drug Administration (FDA) reported that Urea was used in 239 formulations. Concentrations of use for Urea ranged from 0.01% to 10%. Urea is generally recognized as safe by FDA for the following uses: side-seam cements for food contact; an inhibitor or stabilizer in pesticide formulations and formulations applied to animals; internal sizing for paper and paperboard and surface sizing and coating of paper and paper board that contact water-in-oil dairy emulsions, low-moisture fats and oils, moist bakery products, dry solids with surface containing no free fats or oil, and dry solids with the surface of fat or oil; and to facilitate fermentation of wine. Urea is the end product of mammalian protein metabolism and the chief nitrogenous compound of urine. Urea concentrations in muscle, liver, and fetuses of rats increased after a subcutaneous injection of Urea. Urea diffused readily through the placenta and into other maternal and fetal organs. The half-life of Urea injected into rabbits was on the order of several hours, and the reutilization rate was 32.2% to 88.8%. Urea given to rats by a bolus injection or continuous infusion resulted in distribution to the following brain regions: frontal lobe, caudate nucleus, hippocampus, thalamus plus hypothalamus, pons and white matter (corpus callosum). The permeability constant after treatment with Urea of whole skin and the dermis of rabbits was 2.37 +/- 0.13 (x 10(6)) and 1.20 +/- 0.09 (x10(3)) cm/min, respectively. The absorption of Urea across normal and abraded human skin was 9.5% +/- 2.3% and 67.9% +/- 5.6%, respectively. Urea increased the skin penetration of other compounds, including hydrocortisone. No toxicity was observed for Urea at levels as high

  4. Urea hydrolysis and calcium carbonate reaction fronts

    Science.gov (United States)

    Fox, D. T.; Redden, G. D.; Henriksen, J.; Fujita, Y.; Guo, L.; Huang, H.

    2010-12-01

    The mobility of toxic or radioactive metal contaminants in subsurface environments can be reduced by the formation of mineral precipitates that form co-precipitates with the contaminants or that isolate them from the mobile fluid phase. An engineering challenge is to control the spatial distribution of precipitation reactions with respect to: 1) the location of a contaminant, and 2) where reactants are introduced into the subsurface. One strategy being explored for immobilizing contaminants, such as Sr-90, involves stimulating mineral precipitation by forming carbonate ions and hydroxide via the in situ, microbially mediated hydrolysis of urea. A series of column experiments have been conducted to explore how the construction or design of such an in situ reactant production strategy can affect the temporal and spatial distribution of calcium carbonate precipitation, and how the distribution is coupled to changes in permeability. The columns were constructed with silica gel as the porous media. An interval midway through the column contained an adsorbed urease enzyme in order to simulate a biologically active zone. A series of influent solutions were injected to characterize hydraulic properties of the column (e.g., bromide tracer), profiles of chemical conditions and reaction products as the enzyme catalyzes urea hydrolysis (e.g., pH, ammonia, urea), and changes that occur due to CaCO3 precipitation with the introduction of a calcium+urea solutions. In one experiment, hydraulic conductivity was reduced as precipitate accumulated in a layer within the column that had a higher fraction of fine grained silica gel. Subsequent reduction of permeability and flow (for a constant head condition) resulted in displacement of the hydrolysis and precipitation reaction profiles upstream. In another experiment, which lacked the physical heterogeneity (fine grained layer), the precipitation reaction did not result in loss of permeability or flow velocity and the reaction profile

  5. Evolution of urea transporters in vertebrates: adaptation to urea's multiple roles and metabolic sources.

    Science.gov (United States)

    LeMoine, Christophe M R; Walsh, Patrick J

    2015-06-01

    In the two decades since the first cloning of the mammalian kidney urea transporter (UT-A), UT genes have been identified in a plethora of organisms, ranging from single-celled bacteria to metazoans. In this review, focusing mainly on vertebrates, we first reiterate the multiple catabolic and anabolic pathways that produce urea, then we reconstruct the phylogenetic history of UTs, and finally we examine the tissue distribution of UTs in selected vertebrate species. Our analysis reveals that from an ancestral UT, three homologues evolved in piscine lineages (UT-A, UT-C and UT-D), followed by a subsequent reduction to a single UT-A in lobe-finned fish and amphibians. A later internal tandem duplication of UT-A occurred in the amniote lineage (UT-A1), followed by a second tandem duplication in mammals to give rise to UT-B. While the expected UT expression is evident in excretory and osmoregulatory tissues in ureotelic taxa, UTs are also expressed ubiquitously in non-ureotelic taxa, and in tissues without a complete ornithine-urea cycle (OUC). We posit that non-OUC production of urea from arginine by arginase, an important pathway to generate ornithine for synthesis of molecules such as polyamines for highly proliferative tissues (e.g. testis, embryos), and neurotransmitters such as glutamate for neural tissues, is an important evolutionary driving force for the expression of UTs in these taxa and tissues.

  6. New potent calcimimetics: II. Discovery of benzothiazole trisubstituted ureas.

    Science.gov (United States)

    Deprez, Pierre; Temal, Taoues; Jary, Hélène; Auberval, Marielle; Lively, Sarah; Guédin, Denis; Vevert, Jean-Paul

    2013-04-15

    Following the identification of trisubstituted ureas as a promising new chemical series of allosteric modulators of the calcium sensing receptor (CaSR), we further explored the SAR around the urea substitution, leading to the discovery of benzothiazole urea compound 13. This compound is a potent calcimimetic with an EC50=20 nM (luciferase assay). Evaluated in an in vivo model of chronic renal failure (short term and long term in 5/6 nephrectomized rats), benzothiazole urea 13 significantly decreased PTH levels after oral administration while keeping calcemia within the normal range.

  7. Pengolahan Limbah Cair Pabrik Pupuk Urea Menggunakan Advanced Oxidation Processes

    Directory of Open Access Journals (Sweden)

    Darmadi Darmadi

    2014-06-01

    Full Text Available Limbah cair pabrik pupuk urea terdiri dari urea dan amonium yang masing-masing mempunyai konsentrasi berkisar antara 1500-10000 ppm dan 400-3000 ppm. Konsentrasi urea yang tinggi di dalam badan air dapat menyebabkan blooming algae dalam ekosistem tersebut yang dapat mengakibatkan kehidupan biota air lain terserang penyakit. Peristiwa ini terjadi karena kurangnya nutrisi bagi biota air dan sedikitnya sinar matahari yang dapat menembusi permukaan air. Disamping kedua hal tersebut di atas, algae juga dapat memproduksi senyawa beracun bagi biota air dan manusia. Penelitian ini bertujuan untuk mengolah urea menggunakan oksidasi konvensional (H2O2 dan Advanced Oxidation Processes (kombinasi H2O2-Fe2+ pada pH 5 dengan parameter yang digunakan adalah variasi konsen-trasi awal H2O2  dan konsentrasi Fe2+. Hasil percobaan menunjukkan bahwa penurunan konsentrasi urea tertinggi diperoleh pada penggunaan reagen fenton (8000 ppm H2O2 dan 500 ppm Fe2+, yaitu dapat menurunkan urea dari konsentrasi awal urea 2566,145 ppm menjadi 0 ppm. Kinetika reaksi dekomposisi urea menjadi amonium dan amonium menjadi nitrit dan nitrat yang diuji mengikuti laju kinetika reaksi orde 1 (satu terhadap urea dan orde satu terhadap amonium dengan konstanta laju reaksi masing-masing k1 = 0,019 dan k2 = 0,022 min-1.

  8. Fast-starting for a breath: Air breathing in Hoplosternum littorale

    DEFF Research Database (Denmark)

    Domenici, Paolo; Norin, Tommy; Bushnell, Peter G.

    by the fall of a prey item on the water surface, and in tapping motions of goldfish, a behaviour that was interpreted to be food-related. Little is known about C-starts being used outside the context of escaping or feeding. Here, we test the hypothesis that air-breathing fish may use C-starts when gulping air...... at the surface. Air breathing is a common behaviour in many fish species when exposed to hypoxia, although certain species perform air-breathing in normoxia to fill their swim bladders for buoyancy control and/or sound transduction. Hoplosternum littorale is an air-breathing freshwater catfish found in South......, with those of mechanically-triggered C-start escape responses. Our results show that these two behaviours overlap considerably in their kinematics (turning rates and distance covered), suggesting that air breathing in this species is performed using escapelike C-start motions. This demonstrates that C...

  9. Ecological sounds affect breath duration more than artificial sounds.

    Science.gov (United States)

    Murgia, Mauro; Santoro, Ilaria; Tamburini, Giorgia; Prpic, Valter; Sors, Fabrizio; Galmonte, Alessandra; Agostini, Tiziano

    2016-01-01

    Previous research has demonstrated that auditory rhythms affect both movement and physiological functions. We hypothesized that the ecological sounds of human breathing can affect breathing more than artificial sounds of breathing, varying in tones for inspiration and expiration. To address this question, we monitored the breath duration of participants exposed to three conditions: (a) ecological sounds of breathing, (b) artificial sounds of breathing having equal temporal features as the ecological sounds, (c) no sounds (control). We found that participants' breath duration variability was reduced in the ecological sound condition, more than in the artificial sound condition. We suggest that ecological sounds captured the timing of breathing better than artificial sounds, guiding as a consequence participants' breathing. We interpreted our results according to the Theory of Event Coding, providing further support to its validity, and suggesting its possible extension in the domain of physiological functions which are both consciously and unconsciously controlled.

  10. Nitrogen Cycling and Losses Under Rice-Wheat Rotations with Coated Urea and Urea in the Taihu Lake Region

    Institute of Scientific and Technical Information of China (English)

    WANG Xiao-Zhi; ZHU Jian-Guo; GAO Ren; H. YASUKAZU; FENG Ke

    2007-01-01

    A lysimeter experiment with undisturbed soil profiles was carried out to study nitrogen cycling and losses in a paddy soil with applications of coated urea and urea under a rice-wheat rotation system in the Taihu Lake region from 2001 to 2003. Treatments for rice and wheat included urea at conventional, 300 (rice) and 250 (wheat) kg N ha-1, and reduced levels, 150 (rice) and 125 (wheat) kg N ha-1, coated urea at two levels, 100 (rice) and 75 (wheat) kg N ha-1, and 150(rice) and 125 (wheat) kg N ha-1, and a control with no nitrogen arranged in a completely randomized design. The results under two rice-wheat rotations showed that N losses through both NH3 volatilization and runoff in the coated urea treatments were much lower than those in the urea treatments. In the urea treatments N runoff losses were significantly (P < 0.001) positively correlated (r = 0.851) with applied N. N concentration in surface water increased rapidly to maximum two days after urea application and then decreased quickly. However, if there was no heavy rain within five days of fertilizer application, the likelihood of N loss by runoff was not high. As the treatments showed little difference in N loss via percolation, nitrate N in the groundwater of the paddy fields was not directly related to N leaching. The total yieldof the two rice-wheat rotations in the treatment of coated urea at 50% conventional level was higher than that in the treatment of urea at the conventional level. Thus, coated urea was more favorable to rice production and environmental protection than urea.

  11. Nickel hydroxide modified electrodes for urea determination

    Directory of Open Access Journals (Sweden)

    Luiz Henrique Dall´Antonia

    2007-03-01

    Full Text Available Nickel hydroxide films were prepared by electrodeposition from a solution Ni(NO32 0,05 mol L ?¹ on ITO electrodes (Tin oxide doped with Indium on PET-like plastic film, applying a current of - 0,1 A cm ?² during different time intervals between 1800 and 7200 s. The electrochemical behavior of the nickel hydroxide electrode was investigated through a cyclic voltammogram, in NaOH 1,0 mol L ?¹, where it was observed two peaks in the profile in 0,410 and 0,280 V, corresponding to redox couple Ni(II/Ni(III. A sensor for urea presenting a satisfactory answer can be obtained when, after the deposit of the film of Ni(OH2 on the electrode of nickel, it is immersed in a solution of NaOH 1,0 mol L ?¹ and applying a potential of + 0,435 V, where the maximum of the anodic current occurs in the cyclic voltammogram. Analyzing the results it can be observed that, for a range of analite concentration between 5 to 50 m mol L ?¹, the behavior is linear and the sensibility found was of 20,3 mA cm?² (mol L?¹?¹, presenting reproducibility confirming the nickel hydroxide electrodes utilization for the determination of urea.

  12. Lung cancer biomarkers in exhaled breath.

    Science.gov (United States)

    Amann, Anton; Corradi, Massimo; Mazzone, Peter; Mutti, Antonio

    2011-03-01

    Lung cancer is the leading cause of cancer-related mortality worldwide. Methods for early detection of lung cancer, such as computerized tomography scanning technology, often discover a large number of small lung nodules, posing a new problem to radiologists and chest physicians. The vast majority of these nodules will be benign, but there is currently no easy way to determine which nodules represent very early lung cancer. Adjuvant testing with PET imaging and nonsurgical biopsies has a low yield for these small indeterminate nodules, carries potential morbidity and is costly. Indeed, purely morphological criteria seem to be insufficient for distinguishing lung cancer from benign nodules at early stages with sufficient confidence, therefore false positives undergoing surgical resection frequently occur. A molecular approach to the diagnosis of lung cancer through the analysis of exhaled breath could greatly improve the specificity of imaging procedures. A biomarker-driven approach to signs or symptoms possibly due to lung cancer would represent a complementary tool aimed at ruling out (with known error probability) rather than diagnosing lung cancer. Volatile and nonvolatile components of the breath are being studied as biomarkers of lung cancer. Breath testing is noninvasive and potentially inexpensive. There is promise that an accurate lung cancer breath biomarker, capable of being applied clinically, will be developed in the near future. In this article, we summarize some of the rationale for breath biomarker development, review the published literature in this field and provide thoughts regarding future directions.

  13. Sudarshan kriya yoga: Breathing for health

    Directory of Open Access Journals (Sweden)

    Sameer A Zope

    2013-01-01

    Full Text Available Breathing techniques are regularly recommended for relaxation, stress management, control of psychophysiological states, and to improve organ function. Yogic breathing, defined as a manipulation of breath movement, has been shown to positively affect immune function, autonomic nervous system imbalances, and psychological or stress-related disorders. The aim of this study was to assess and provide a comprehensive review of the physiological mechanisms, the mind-body connection, and the benefits of Sudarshan Kriya Yoga (SKY in a wide range of clinical conditions. Various online databases searched were Medline, Psychinfo, EMBASE, and Google Scholar. All the results were carefully screened and articles on SKY were selected. The references from these articles were checked to find any other potentially relevant articles. SKY, a unique yogic breathing practice, involves several types of cyclical breathing patterns, ranging from slow and calming to rapid and stimulating. There is mounting evidence to suggest that SKY can be a beneficial, low-risk, low-cost adjunct to the treatment of stress, anxiety, post-traumatic stress disorder, depression, stress-related medical illnesses, substance abuse, and rehabilitation of criminal offenders.

  14. Pulse Ejection Presentation System Synchronized with Breathing

    Science.gov (United States)

    Kadowaki, Ami; Sato, Junta; Ohtsu, Kaori; Bannai, Yuichi; Okada, Kenichi

    Trials on transmission of olfactory information together with audio/visual information are currently being conducted in the field of multimedia. However, continuous emission of scents in high concentration creates problems of human adaptation and remnant odors in air. To overcome such problems we developed an olfactory display in conjunction with Canon Inc. This display has high emission control in the ink-jet so that it can provide stable pulse emission of scents. Humans catch a scent when they breathe in and inhale smell molecules in air. Therefore, it is important that the timing of scent presentation is synchronized with human breathing. We also developed a breath sensor which detects human inspiration. In this study, we combined the olfactory display with the breath sensor to make a pulse ejection presentation system synchronized the breath. The experimental evaluation showed that the system had more than 90 percent of detection rate. Another evaluation was held at KEIO TECHNO-MALL 2007. From questionnaire results of the participants, we found that the system made the user feel continuous sense of smell avoiding adaptation. It is expected that our system enables olfactory information to be synchronized with audio/visual information in arbitrary duration at any time.

  15. Effect of urea and urea-gamma treatments on cellulose degradation of Thai rice straw and corn stalk

    Energy Technology Data Exchange (ETDEWEB)

    Banchorndhevakul, Siriwattana E-mail: siriwatt@ji-net.com

    2002-08-01

    Cellulose degradation of 20% urea treated and 20% urea-10 kGy gamma treated Thai rice straw and corn stalk showed that combination effect of urea and gamma radiation gave a higher % decrease in neutral detergent fiber (NDF), acid detergent fiber (ADF), acid detergent lignin (ADL), cellulose, hemicellulose, and lignin and cutin in comparison with urea effect only for both room temperature storage and room temperature +258 K storage. The results also indicated that cellulose degradation proceeded with time, even at 258 K. A drastic drop to less than half of the original contents in NDF, ADF, and ADL could not be obtained in this study.

  16. Laboratory Experiments to Evaluate Matrix Diffusion of Dissolved Organic Carbon Carbon-14 in Southern Nevada Fractured-rock Aquifers

    Energy Technology Data Exchange (ETDEWEB)

    Hershey, Ronald L. [Nevada University, Reno, NV (United States). Desert Research Institute; Fereday, Wyatt [Nevada University, Reno, NV (United States). Desert Research Institute

    2016-05-01

    Dissolved inorganic carbon (DIC) carbon-14 (14C) is used to estimate groundwater ages by comparing the DIC 14C content in groundwater in the recharge area to the DIC 14C content in the downgradient sampling point. However, because of chemical reactions and physical processes between groundwater and aquifer rocks, the amount of DIC 14C in groundwater can change and result in 14C loss that is not because of radioactive decay. This loss of DIC 14C results in groundwater ages that are older than the actual groundwater ages. Alternatively, dissolved organic carbon (DOC) 14C in groundwater does not react chemically with aquifer rocks, so DOC 14C ages are generally younger than DIC 14C ages. In addition to chemical reactions, 14C ages may also be altered by the physical process of matrix diffusion. The net effect of a continuous loss of 14C to the aquifer matrix by matrix diffusion and then radioactive decay is that groundwater appears to be older than it actually is. Laboratory experiments were conducted to measure matrix diffusion coefficients for DOC 14C in volcanic and carbonate aquifer rocks from southern Nevada. Experiments were conducted using bromide (Br-) as a conservative tracer and 14C-labeled trimesic acid (TMA) as a surrogate for groundwater DOC. Outcrop samples from six volcanic aquifers and five carbonate aquifers in southern Nevada were used. The average DOC 14C matrix diffusion coefficient for volcanic rocks was 2.9 x 10-7 cm2/s, whereas the average for carbonate rocks was approximately the same at 1.7 x 10-7 cm2/s. The average Br- matrix diffusion coefficient for volcanic rocks was 10.4 x 10-7 cm2/s, whereas the average for carbonate rocks was less at 6.5 x 10-7 cm2/s. Carbonate rocks exhibited greater variability in

  17. Technologies for Clinical Diagnosis Using Expired Human Breath Analysis

    Directory of Open Access Journals (Sweden)

    Thalakkotur Lazar Mathew

    2015-02-01

    Full Text Available This review elucidates the technologies in the field of exhaled breath analysis. Exhaled breath gas analysis offers an inexpensive, noninvasive and rapid method for detecting a large number of compounds under various conditions for health and disease states. There are various techniques to analyze some exhaled breath gases, including spectrometry, gas chromatography and spectroscopy. This review places emphasis on some of the critical biomarkers present in exhaled human breath, and its related effects. Additionally, various medical monitoring techniques used for breath analysis have been discussed. It also includes the current scenario of breath analysis with nanotechnology-oriented techniques

  18. Decompression sickness following breath-hold diving.

    Science.gov (United States)

    Schipke, J D; Gams, E; Kallweit, Oliver

    2006-01-01

    Despite convincing evidence of a relationship between breath-hold diving and decompression sickness (DCS), the causal connection is only slowly being accepted. Only the more recent textbooks have acknowledged the risks of repetitive breath-hold diving. We compare four groups of breath-hold divers: (1) Japanese and Korean amas and other divers from the Pacific area, (2) instructors at naval training facilities, (3) spear fishers, and (4) free-dive athletes. While the number of amas is likely decreasing, and Scandinavian Navy training facilities recorded only a few accidents, the number of spear fishers suffering accidents is on the rise, in particular during championships or using scooters. Finally, national and international associations (e.g., International Association of Free Drives [IAFD] or Association Internationale pour Le Developpment De L'Apnee [AIDA]) promote free-diving championships including deep diving categories such as constant weight, variable weight, and no limit. A number of free-diving athletes, training for or participating in competitions, are increasingly accident prone as the world record is presently set at a depth of 171 m. This review presents data found after searching Medline and ISI Web of Science and using appropriate Internet search engines (e.g., Google). We report some 90 cases in which DCS occurred after repetitive breath-hold dives. Even today, the risk of suffering from DCS after repetitive breath-hold diving is often not acknowledged. We strongly suggest that breath-hold divers and their advisors and physicians be made aware of the possibility of DCS and of the appropriate therapeutic measures to be taken when DCS is suspected. Because the risk of suffering from DCS increases depending on depth, bottom time, rate of ascent, and duration of surface intervals, some approaches to assess the risks are presented. Regrettably, none of these approaches is widely accepted. We propose therefore the development of easily manageable

  19. Breath testing and personal exposure--SIFT-MS detection of breath acetonitrile for exposure monitoring.

    Science.gov (United States)

    Storer, Malina; Curry, Kirsty; Squire, Marie; Kingham, Simon; Epton, Michael

    2015-05-26

    Breath testing has potential for the rapid assessment of the source and impact of exposure to air pollutants. During the development of a breath test for acetonitrile using selected ion flow tube mass spectrometry (SIFT-MS) raised acetonitrile concentrations in the breath of volunteers were observed that could not be explained by known sources of exposure. Workplace/laboratory exposure to acetonitrile was proposed since this was common to the volunteers with increased breath concentrations. SIFT-MS measurements of acetonitrile in breath and air were used to confirm that an academic chemistry laboratory was the source of exposure to acetonitrile, and quantify the changes that occurred to exhaled acetonitrile after exposure. High concentrations of acetonitrile were detected in the air of the chemistry laboratory. However, concentrations in the offices were not significantly different across the campus. There was a significant difference in the exhaled acetonitrile concentrations of people who worked in the chemistry laboratories (exposed) and those who did not (non-exposed). SIFT-MS testing of air and breath made it possible to determine that occupational exposure to acetonitrile in the chemistry laboratory was the cause of increased exhaled acetonitrile. Additionally, the sensitivity was adequate to measure the changes to exhaled amounts and found that breath concentrations increased quickly with short exposure and remained increased even after periods of non-exposure. There is potential to add acetonitrile to a suite of VOCs to investigate source and impact of poor air quality.

  20. Nitrification and Anammox with urea as the energy source

    NARCIS (Netherlands)

    Sliekers, A.O.; Haaijer, S.C.M.; Schmid, M.C.; Harhangi, R.H.; Verwegen, K.; Kuenen, J.G.; Jetten, M.S.M.

    2004-01-01

    Urea is present in many ecosystems and can be used as an energy source by chemolithotrophic aerobic ammonia oxidizing bacteria (AOB). Thus the utilization of urea in comparison to ammonia, by AOB as well as anaerobic ammonia oxidizing (Anammox) bacteria was investigated, using enrichments cultures,

  1. 21 CFR 862.1770 - Urea nitrogen test system.

    Science.gov (United States)

    2010-04-01

    ... 21 Food and Drugs 8 2010-04-01 2010-04-01 false Urea nitrogen test system. 862.1770 Section 862.1770 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED... measure urea nitrogen (an end-product of nitrogen metabolism) in whole blood, serum, plasma, and...

  2. 40 CFR 721.9925 - Aminoethylethylene urea methacrylamide.

    Science.gov (United States)

    2010-07-01

    ... 40 Protection of Environment 30 2010-07-01 2010-07-01 false Aminoethylethylene urea methacrylamide... Substances § 721.9925 Aminoethylethylene urea methacrylamide. (a) Chemical substance and significant new uses subject to reporting. (1) The chemical substance identified generically as an aminoethylethylene...

  3. Solid and solution phase combinatorial synthesis of ureas

    NARCIS (Netherlands)

    Nieuwenhuijzen, JW; Conti, PGM; Ottenheijm, HCJ; Linders, JTM

    1998-01-01

    An efficient parallel synthesis of ureas based on amino acids is described, both in solution and on solid phase. 1,1'-Carbonylbisbenzotriazole 2 is used as the coupling reagent. The ureas 5 and 10 were obtained in high yield (80-100%) and purity (71-97%). (C) 1998 Elsevier Science Ltd. All rights re

  4. Physiological and transcriptomic aspects of urea uptake and assimilation in Arabidopsis plants.

    Science.gov (United States)

    Mérigout, Patricia; Lelandais, Maud; Bitton, Frédérique; Renou, Jean-Pierre; Briand, Xavier; Meyer, Christian; Daniel-Vedele, Françoise

    2008-07-01

    Urea is the major nitrogen (N) form supplied as fertilizer in agriculture, but it is also an important N metabolite in plants. Urea transport and assimilation were investigated in Arabidopsis (Arabidopsis thaliana). Uptake studies using (15)N-labeled urea demonstrated the capacity of Arabidopsis to absorb urea and that the urea uptake was regulated by the initial N status of the plants. Urea uptake was stimulated by urea but was reduced by the presence of ammonium nitrate in the growth medium. N deficiency in plants did not affect urea uptake. Urea exerted a repressive effect on nitrate influx, whereas urea enhanced ammonium uptake. The use of [(15)N]urea and [(15)N]ammonium tracers allowed us to show that urea and ammonium assimilation pathways were similar. Finally, urea uptake was less efficient than nitrate uptake, and urea grown-plants presented signs of N starvation. We also report the first analysis, to our knowledge, of Arabidopsis gene expression profiling in response to urea. Our transcriptomic approach revealed that nitrate and ammonium transporters were transcriptionally regulated by urea as well as key enzymes of the glutamine synthetase-glutamate synthase pathway. AtDUR3, a high-affinity urea transporter in Arabidopsis, was strongly up-regulated by urea. Moreover, our transcriptomic data suggest that other genes are also involved in urea influx.

  5. Medication effects on sleep and breathing.

    Science.gov (United States)

    Seda, Gilbert; Tsai, Sheila; Lee-Chiong, Teofilo

    2014-09-01

    Sleep respiration is regulated by circadian, endocrine, mechanical and chemical factors, and characterized by diminished ventilatory drive and changes in Pao2 and Paco2 thresholds. Hypoxemia and hypercapnia are more pronounced during rapid eye movement. Breathing is influenced by sleep stage and airway muscle tone. Patient factors include medical comorbidities and body habitus. Medications partially improve obstructive sleep apnea and stabilize periodic breathing at altitude. Potential adverse consequences of medications include precipitation or worsening of disorders. Risk factors for adverse medication effects include aging, medical disorders, and use of multiple medications that affect respiration.

  6. Comparison of two devices and two breathing patterns for exhaled breath condensate sampling.

    Directory of Open Access Journals (Sweden)

    Eva-Maria Hüttmann

    Full Text Available Analysis of exhaled breath condensate (EBC is a noninvasive method to access the epithelial lining fluid of the lungs. Due to standardization problems the method has not entered clinical practice. The aim of the study was to assess the comparability for two commercially available devices in healthy controls. In addition, we assessed different breathing patterns in healthy controls with protein markers to analyze the source of the EBC.EBC was collected from ten subjects using the RTube and ECoScreen Turbo in a randomized crossover design, twice with every device--once in tidal breathing and once in hyperventilation. EBC conductivity, pH, surfactant protein A, Clara cell secretory protein and total protein were assessed. Bland-Altman plots were constructed to display the influence of different devices or breathing patterns and the intra-class correlation coefficient (ICC was calculated. The volatile organic compound profile was measured using the electronic nose Cyranose 320. For the analysis of these data, the linear discriminant analysis, the Mahalanobis distances and the cross-validation values (CVV were calculated.Neither the device nor the breathing pattern significantly altered EBC pH or conductivity. ICCs ranged from 0.61 to 0.92 demonstrating moderate to very good agreement. Protein measurements were greatly influenced by breathing pattern, the device used, and the way in which the results were reported. The electronic nose could distinguish between different breathing patterns and devices, resulting in Mahalanobis distances greater than 2 and CVVs ranging from 64% to 87%.EBC pH and (to a lesser extent EBC conductivity are stable parameters that are not influenced by either the device or the breathing patterns. Protein measurements remain uncertain due to problems of standardization. We conclude that the influence of the breathing maneuver translates into the necessity to keep the volume of ventilated air constant in further studies.

  7. Urea enhances the photodynamic efficiency of methylene blue.

    Science.gov (United States)

    Nuñez, Silvia C; Yoshimura, Tania M; Ribeiro, Martha S; Junqueira, Helena C; Maciel, Cleiton; Coutinho-Neto, Maurício D; Baptista, Maurício S

    2015-09-01

    Methylene blue (MB) is a well-known photosensitizer used mostly for antimicrobial photodynamic therapy (APDT). MB tends to aggregate, interfering negatively with its singlet oxygen generation, because MB aggregates lean towards electron transfer reactions, instead of energy transfer with oxygen. In order to avoid MB aggregation we tested the effect of urea, which destabilizes solute-solute interactions. The antimicrobial efficiency of MB (30 μM) either in water or in 2M aqueous urea solution was tested against a fungus (Candida albicans). Samples were kept in the dark and irradiation was performed with a light emitting diode (λ = 645 nm). Without urea, 9 min of irradiation was needed to achieve complete microbial eradication. In urea solution, complete eradication was obtained with 6 min illumination (light energy of 14.4 J). The higher efficiency of MB/urea solution was correlated with a smaller concentration of dimers, even in the presence of the microorganisms. Monomer to dimer concentration ratios were extracted from the absorption spectra of MB solutions measured as a function of MB concentration at different temperatures and at different concentrations of sodium chloride and urea. Dimerization equilibrium decreased by 3 and 6 times in 1 and 2M urea, respectively, and increased by a factor of 6 in 1M sodium chloride. The destabilization of aggregates by urea seems to be applied to other photosensitizers, since urea also destabilized aggregation of Meso-tetra(4-n-methyl-pyridyl)porphyrin, which is a positively charged porphyrin. We showed that urea destabilizes MB aggregates mainly by causing a decrease in the enthalpic gain of dimerization, which was exactly the opposite of the effect of sodium chloride. In order to understand this phenomenon at the molecular level, we computed the free energy for the dimer association process (ΔG(dimer)) in aqueous solution as well as its enthalpic component in aqueous and in aqueous/urea solutions by molecular dynamics

  8. Structure and permeation mechanism of a mammalian urea transporter

    Energy Technology Data Exchange (ETDEWEB)

    Levin, Elena J.; Cao, Yu; Enkavi, Giray; Quick, Matthias; Pan, Yaping; Tajkhorshid, Emad; Zhou, Ming (UIUC); (Columbia)

    2012-09-17

    As an adaptation to infrequent access to water, terrestrial mammals produce urine that is hyperosmotic to plasma. To prevent osmotic diuresis by the large quantity of urea generated by protein catabolism, the kidney epithelia contain facilitative urea transporters (UTs) that allow rapid equilibration between the urinary space and the hyperosmotic interstitium. Here we report the first X-ray crystal structure of a mammalian UT, UT-B, at a resolution of 2.36 {angstrom}. UT-B is a homotrimer and each protomer contains a urea conduction pore with a narrow selectivity filter. Structural analyses and molecular dynamics simulations showed that the selectivity filter has two urea binding sites separated by an approximately 5.0 kcal/mol energy barrier. Functional studies showed that the rate of urea conduction in UT-B is increased by hypoosmotic stress, and that the site of osmoregulation coincides with the location of the energy barrier.

  9. Breathing adapted radiotherapy for breast cancer: comparison of free breathing gating with the breath-hold technique

    DEFF Research Database (Denmark)

    Korreman, Stine Sofia; Pedersen, Anders N; Nøttrup, Trine Jakobi;

    2005-01-01

    -hold (EBH). The Varian Real-time Position Management system (RPM) was used to monitor respiratory movement and to gate the scanner. For each breathing phase, a population based internal margin (IM) was estimated based on average chest wall excursion, and incorporated into an individually optimised three...

  10. The nutritional management of urea cycle disorders.

    Science.gov (United States)

    Leonard, J V

    2001-01-01

    Diet is one of the mainstays of the treatment of patients with urea cycle disorders. The protein intake should be adjusted to take account of the inborn error and its severity and the patient's age, growth rate, and individual preferences. Currently, the widely used standards for protein intake are probably more generous than necessary, particularly for those with the more severe variants. Most patients, except those with arginase deficiency, will need supplements of arginine, but the value of other supplements including citrate and carnitine is unclear. Any patient on a low-protein diet should be monitored clinically and with appropriate laboratory tests. All should have an emergency (crisis) regimen to prevent decompensation during periods of metabolic stress.

  11. Hydrolyzable polyureas bearing hindered urea bonds.

    Science.gov (United States)

    Ying, Hanze; Cheng, Jianjun

    2014-12-10

    Hydrolyzable polymers are widely used materials that have found numerous applications in biomedical, agricultural, plastic, and packaging industrials. They usually contain ester and other hydrolyzable bonds, such as anhydride, acetal, ketal, or imine, in their backbone structures. Here, we report the first design of hydrolyzable polyureas bearing dynamic hindered urea bonds (HUBs) that can reversibly dissociate to bulky amines and isocyanates, the latter of which can be further hydrolyzed by water, driving the equilibrium to facilitate the degradation of polyureas. Polyureas bearing 1-tert-butyl-1-ethylurea bonds that show high dynamicity (high bond dissociation rate), in the form of either linear polymers or cross-linked gels, can be completely degraded by water under mild conditions. Given the simplicity and low cost for the production of polyureas by simply mixing multifunctional bulky amines and isocyanates, the versatility of the structures, and the tunability of the degradation profiles of HUB-bearing polyureas, these materials are potentially of very broad applications.

  12. In vivo proton MRS of normal pancreas metabolites during breath-holding and free-breathing

    Energy Technology Data Exchange (ETDEWEB)

    Su, T.-H. [Department of Radiology, Beijing Friendship Hospital, Capital Medical University, 95 Yong-An Road, Beijing (China); Jin, E.-H., E-mail: erhujin1@hotmail.com [Department of Radiology, Beijing Friendship Hospital, Capital Medical University, 95 Yong-An Road, Beijing (China); Shen, H. [GE China Company Ltd, Healthcare, General Electric Company, Beijing (China); Zhang, Y.; He, W. [Department of Radiology, Beijing Friendship Hospital, Capital Medical University, 95 Yong-An Road, Beijing (China)

    2012-07-15

    Aim: To characterize normal pancreas metabolites using in vivo proton magnetic resonance spectroscopy ({sup 1}H MRS) at 3 T under conditions of breath-holding and free-breathing. Materials and methods: The pancreases of 32 healthy volunteers were examined using {sup 1}H MRS during breath-holding and free-breathing acquisitions in a single-voxel point-resolved selective spectroscopy sequence (PRESS) technique using a 3 T MRI system. Resonances were compared between paired spectra of the two breathing modes. Furthermore, correlations between lipid (Lip) content and age, body-mass index (BMI), as well as choline (Cho) peak visibility of the normal pancreas were analysed during breath-holding. Results: Twenty-nine pairs of spectra were successfully obtained showing three major resonances, Lip, Cho, cholesterol and the unsaturated parts of the olefinic region of fatty acids (Chol + Unsat). Breath-hold spectra were generally better, with higher signal-to-noise ratios (SNR; Z=-2.646, p = 0.008) and Cho peak visible status (Z=-2.449, p = 0.014). Correlations were significant between spectra acquired by the two breathing modes, especially for Lip height, Lip area, and the area of other peaks at 1.9-4.1 ppm. However, the Lip resonance was significantly different between the spectra of the two breathing modes (p < 0.05). In the breath-holding spectra, there were significant positive correlations between Lip peak height, area, and age (r = 0.491 and 0.521, p = 0.007 and 0.004), but not between Lip peak area and BMI. There was no statistical difference in Cho resonances between males and females. The Lip peak height and area were significantly higher in the Cho peak invisible group than in the Cho peak visible group (t = 2.661 and 2.353, p = 0.030 and 0.043). Conclusion: In vivo{sup 1}H MRS of the normal pancreas at 3 T is technically feasible and can characterize several metabolites. {sup 1}H MRS during breath-holding acquisition is superior to that during free-breathing

  13. Effects of nitrogen supply on inter-organ fluxes of urea-N and renal urea-N kinetics in lactating Holstein cows

    DEFF Research Database (Denmark)

    Røjen, Betina Amdisen; Theil, Peter Kappel; Kristensen, Niels Bastian

    2011-01-01

    The effects of decreasing ruminal urea infusion in lactating dairy cows fed a basal diet deficient in rumen degradable protein on inter-organ urea-N fluxes, epithelial urea-N extraction, and renal urea-N kinetics were investigated. Eight Danish Holstein cows fitted with a ruminal cannula...... and permanent indwelling catheters in the major splanchnic blood vessels and the gastrosplenic vein were used. The cows were randomly allocated to a triplicate incomplete 3 × 3 Latin square design with 14-d periods. Treatments were continuous ventral ruminal infusion of water, 4.1 g of feed urea/kg of dry...... matter intake, and 8.5 g of feed urea/kg of dry matter intake. Dry matter intake and milk yield decreased linearly with decreasing urea infusion. Arterial blood urea-N and ruminal ammonia concentrations decreased linearly with decreasing urea infusion. In absolute amounts, the urea-N recycling did...

  14. Mitochondrial citrulline synthesis from ammonia and glutamine in the liver of ureogenic air-breathing catfish, Clarias batrachus (Linnaeus).

    Science.gov (United States)

    Kharbuli, Zaiba Y; Biswas, Kuheli; Saha, Nirmalendu

    2007-12-01

    The possible synthesis of citrulline, a rate limiting step for urea synthesis via the ornithine-urea cycle (OUC) in teleosts was tested both in the presence of ammonia and glutamine as nitrogen-donating substrates by the isolated liver mitochondria of ureogenic air-breathing walking catfish, C. batrachus. Both ammonia and glutamine could be used as nitrogen-donating substrates for the synthesis of citrulline by the isolated liver mitochondria, since the rate of citrulline synthesis was almost equal in presence of both the substrates. The citrulline synthesis by the isolated liver mitochondria requires succinate at a concentration of 0.1 mM as an energy source, and also requires the involvement of intramitochondrial carbonic anhydrase activity for supplying HCO3 as another substrate for citrulline synthesis. The rate of citrulline synthesis was further stimulated significantly by the isolated liver mitochondria of the fish after pre-exposure to 25 mM NH4Cl for 7 days. Due to possessing this biochemical adaptational strategy leading to the amelioration of ammonia toxicity mainly by channeling ammonia directly and/or via the formation of glutamine to the OUC, this air-breathing catfish could succeed in surviving in high external ammonia, which it faces in its natural habitat in certain seasons of the year.

  15. Hydrogen bonding of formamide, urea, urea monoxide and their thio-analogs with water and homodimers

    Indian Academy of Sciences (India)

    Damanjit Kaur; Shweta Khanna

    2014-11-01

    Ab initio and DFT methods have been employed to study the hydrogen bonding ability of formamide, urea, urea monoxide, thioformamide, thiourea and thiourea monoxide with one water molecule and the homodimers of the selected molecules. The stabilization energies associated with themonohydrated adducts and homodimers’ formation were evaluated at B3LYP/6-311++G** and MP2/6-311++G∗∗ levels. The energies were corrected for zero-point vibrational energies and basis set superposition error using counterpoise method. Atoms in molecules study has been carried out in order to characterize the hydrogen bonds through the changes in electron density and laplacian of electron density. A natural energy decomposition and natural bond orbital analysis was performed to understand the nature of hydrogen bonding.

  16. A review of factors influencing milk urea concentration and its relationship with urinary urea excretion in lactating dairy cattle

    NARCIS (Netherlands)

    Spek, J.W.; Dijkstra, J.; Duinkerken, van G.; Bannink, A.

    2013-01-01

    Milk urea nitrogen (MUN) concentration in dairy cows may serve as an on-farm indicator to guide nutritional strategies and to help reduce emissions of nitrogen (N) to the environment. Excretion of urinary urea nitrogen (UUN) is positively related to MUN, but the relationship is highly variable. The

  17. Influence of milk urea concentration on fractional urea disappearance rate from milk to blood plasma in dairy cows

    NARCIS (Netherlands)

    Spek, J.W.; Dijkstra, J.; Bannink, A.

    2016-01-01

    The relationship between milk urea nitrogen (MUN; mg of N/dL) and urinary N excretion is affected, among others, by diurnal dynamics in MUN, which in turn is largely influenced by feed intake pattern and characteristics of urea transfer from blood plasma to milk and vice versa. This study aimed t

  18. 42 CFR 84.195 - Breathing tubes; minimum requirements.

    Science.gov (United States)

    2010-10-01

    ... Cartridge Respirators § 84.195 Breathing tubes; minimum requirements. Flexible breathing tubes used in conjunction with respirators shall be designed and constructed to prevent: (a) Restriction of free...

  19. 42 CFR 84.132 - Breathing tubes; minimum requirements.

    Science.gov (United States)

    2010-10-01

    ... Respirators § 84.132 Breathing tubes; minimum requirements. Flexible breathing tubes used in conjunction with supplied-air respirators shall be designed and constructed to prevent: (a) Restriction of free...

  20. Apolo Ohno: Breathing Easier | NIH MedlinePlus the Magazine

    Science.gov (United States)

    ... please turn Javascript on. Feature: Breathing Easier Apolo Ohno: Breathing Easier Past Issues / Fall 2013 Table of ... skating. What does the future hold for Apolo Ohno? Even though I'm no longer skating competitively, ...

  1. Improving long term outcomes in urea cycle disorders-report from the Urea Cycle Disorders Consortium.

    Science.gov (United States)

    Waisbren, Susan E; Gropman, Andrea L; Batshaw, Mark L

    2016-07-01

    The Urea Cycle Disorders Consortium (UCDC) has conducted, beginning in 2006, a longitudinal study (LS) of eight enzyme deficiencies/transporter defects associated with the urea cycle. These include N-acetylglutamate synthase deficiency (NAGSD); Carbamyl phosphate synthetase 1 deficiency (CPS1D); Ornithine transcarbamylase deficiency (OTCD); Argininosuccinate synthetase deficiency (ASSD) (Citrullinemia); Argininosuccinate lyase deficiency (ASLD) (Argininosuccinic aciduria); Arginase deficiency (ARGD, Argininemia); Hyperornithinemia, hyperammonemia, homocitrullinuria (HHH) syndrome (or mitochondrial ornithine transporter 1 deficiency [ORNT1D]); and Citrullinemia type II (mitochondrial aspartate/glutamate carrier deficiency [CITRIN]). There were 678 UCD patients enrolled in 14 sites in the U.S., Canada, and Europe at the writing of this paper. This review summarizes findings of the consortium related to outcome, focusing primarily on neuroimaging findings and neurocognitive function. Neuroimaging studies in late onset OTCD offered evidence that brain injury caused by biochemical dysregulation may impact functional neuroanatomy serving working memory processes, an important component of executive function and regulation. Additionally, there were alteration in white mater microstructure and functional connectivity at rest. Intellectual deficits in OTCD and other urea cycle disorders (UCD) vary. However, when neuropsychological deficits occur, they tend to be more prominent in motor/performance areas on both intelligence tests and other measures. In some disorders, adults performed significantly less well than younger patients. Further longitudinal follow-up will reveal whether this is due to declines throughout life or to improvements in diagnostics (especially newborn screening) and treatments in the younger generation of patients.

  2. The urea carboxylase and allophanate hydrolase activities of urea amidolyase are functionally independent.

    Science.gov (United States)

    Lin, Yi; Boese, Cody J; St Maurice, Martin

    2016-10-01

    Urea amidolyase (UAL) is a multifunctional biotin-dependent enzyme that contributes to both bacterial and fungal pathogenicity by catalyzing the ATP-dependent cleavage of urea into ammonia and CO2 . UAL is comprised of two enzymatic components: urea carboxylase (UC) and allophanate hydrolase (AH). These enzyme activities are encoded on separate but proximally related genes in prokaryotes while, in most fungi, they are encoded by a single gene that produces a fusion enzyme on a single polypeptide chain. It is unclear whether the UC and AH activities are connected through substrate channeling or other forms of direct communication. Here, we use multiple biochemical approaches to demonstrate that there is no substrate channeling or interdomain/intersubunit communication between UC and AH. Neither stable nor transient interactions can be detected between prokaryotic UC and AH and the catalytic efficiencies of UC and AH are independent of one another. Furthermore, an artificial fusion of UC and AH does not significantly alter the AH enzyme activity or catalytic efficiency. These results support the surprising functional independence of AH from UC in both the prokaryotic and fungal UAL enzymes and serve as an important reminder that the evolution of multifunctional enzymes through gene fusion events does not always correlate with enhanced catalytic function.

  3. Synthesis of aluminum nitride nanoparticles by a facile urea glass route and influence of urea/metal molar ratio

    Energy Technology Data Exchange (ETDEWEB)

    Gao, Zhifang; Wan, Yizao [School of Materials Science and Engineering, and Tianjin Key Laboratory of Composite and Functional Materials, Tianjin University, Tianjin 300072 (China); Xiong, Guangyao [School of Mechanical and Electrical Engineering, East China Jiaotong University, Nanchang, Jiangxi 330013 (China); Guo, Ruisong [School of Materials Science and Engineering, and Tianjin Key Laboratory of Composite and Functional Materials, Tianjin University, Tianjin 300072 (China); Luo, Honglin, E-mail: hlluo@tju.edu.cn [School of Materials Science and Engineering, and Tianjin Key Laboratory of Composite and Functional Materials, Tianjin University, Tianjin 300072 (China)

    2013-09-01

    Attention toward nanosized aluminum nitride (AlN) was rapidly increasing due to its physical and chemical characteristics. In this work, nanocrystalline AlN particles were prepared via a simple urea glass route. The effect of the urea/metal molar ratio on the crystal structure and morphology of nanocrystalline AlN particles was studied using X-ray powder diffraction (XRD), scanning electron microscope (SEM) and transmission electron microscope (TEM). The results revealed that the morphology and the crystal structure of AlN nanoparticles could be controlled by adjusting the urea/metal ratio. Furthermore, a mixture of Al{sub 2}O{sub 3} and h-AlN was detected at the urea/metal molar ratio of 4 due to the inadequate urea content. With increasing the molar ratio, the pure h-AlN was obtained. In addition, the nucleation and growth mechanisms of AlN nanocrystalline were proposed.

  4. Measuring breath acetone for monitoring fat loss: Review

    OpenAIRE

    Anderson, Joseph C.

    2015-01-01

    Objective Endogenous acetone production is a by‐product of the fat metabolism process. Because of its small size, acetone appears in exhaled breath. Historically, endogenous acetone has been measured in exhaled breath to monitor ketosis in healthy and diabetic subjects. Recently, breath acetone concentration (BrAce) has been shown to correlate with the rate of fat loss in healthy individuals. In this review, the measurement of breath acetone in healthy subjects is evaluated for its utility in...

  5. Breathing Better with a COPD Diagnosis

    Science.gov (United States)

    Now that you kNow it’s CoPD, here’s how to breathe better. You have taken the important step of being aware of your symptoms, and seeing your doctor ... care provider for testing and a diagnosis. While COPD (Chronic Obstructive Pulmonary Disease) is a serious lung ...

  6. Ineffective breathing pattern related to malnutrition.

    Science.gov (United States)

    Openbrier, D R; Covey, M

    1987-03-01

    This article has highlighted the problem of malnutrition in the stable COPD patient and the critically ill, hypercatabolic patient, and has reviewed resultant mechanisms which influence the alteration of breathing pattern. These complex patients present a challenge for the nurse. Table 1 briefly summarizes the manifestations of malnutrition, goals, interventions and expected outcomes of the nursing diagnosis, ineffective breathing pattern related to malnutrition. The goal of the interventions is to modify the cause (malnutrition) of the nursing diagnosis (altered breathing pattern). The success of the interventions will lead to the achievement of expected outcome As expected outcomes are achieved, relief of signs and symptoms related to the nursing diagnosis will occur. The nurse caring for the patient with actual or potential malnutrition must be knowledgeable about the physiology of malnutrition and effect on breathing pattern. It is essential that the nurse assess and provide appropriate nutritional support and evaluate progress toward expected outcomes. In the event that expected outcomes are not achieved, reassessment with modification of interventions is necessary. Nurses play a key role in the total health care delivery to these complex patients. Further study will strengthen the research base of nursing interventions.

  7. Multi-layered breathing architectural envelope

    DEFF Research Database (Denmark)

    Lund Larsen, Andreas; Foged, Isak Worre; Jensen, Rasmus Lund

    2014-01-01

    A multi layered breathing envelope is developed as a method of natural ventilation. The two main layers consist of mineral wool and air permeable concrete. The mineral wool works as a dynamic insulation and the permeable concrete as a heat recovery system with a high thermal mass for heat storage...

  8. Fast and accurate exhaled breath ammonia measurement.

    Science.gov (United States)

    Solga, Steven F; Mudalel, Matthew L; Spacek, Lisa A; Risby, Terence H

    2014-06-11

    This exhaled breath ammonia method uses a fast and highly sensitive spectroscopic method known as quartz enhanced photoacoustic spectroscopy (QEPAS) that uses a quantum cascade based laser. The monitor is coupled to a sampler that measures mouth pressure and carbon dioxide. The system is temperature controlled and specifically designed to address the reactivity of this compound. The sampler provides immediate feedback to the subject and the technician on the quality of the breath effort. Together with the quick response time of the monitor, this system is capable of accurately measuring exhaled breath ammonia representative of deep lung systemic levels. Because the system is easy to use and produces real time results, it has enabled experiments to identify factors that influence measurements. For example, mouth rinse and oral pH reproducibly and significantly affect results and therefore must be controlled. Temperature and mode of breathing are other examples. As our understanding of these factors evolves, error is reduced, and clinical studies become more meaningful. This system is very reliable and individual measurements are inexpensive. The sampler is relatively inexpensive and quite portable, but the monitor is neither. This limits options for some clinical studies and provides rational for future innovations.

  9. Sleep-disordered breathing in acromegaly

    Directory of Open Access Journals (Sweden)

    L K Dzeranova

    2013-03-01

    Full Text Available Sleep-disordered breathing is higly prevalent in acromegaly, disturbing patients quality of life and increasing the risk of acute cardiovascular compications. Presented clinical case discusses key considerations for timely diagnosis of sleep apnea syndrome and treatment planning. The case of 41 y.o. woman with newly diagnosed acromegaly and concomitant sleep apnea is typical for this disease.

  10. Coordination of breathing with nonrespiratory activities.

    Science.gov (United States)

    Bartlett, Donald; Leiter, James C

    2012-04-01

    Many articles in this section of Comprehensive Physiology are concerned with the development and function of a central pattern generator (CPG) for the control of breathing in vertebrate animals. The action of the respiratory CPG is extensively modified by cortical and other descending influences as well as by feedback from peripheral sensory systems. The central nervous system also incorporates other CPGs, which orchestrate a wide variety of discrete and repetitive, voluntary and involuntary movements. The coordination of breathing with these other activities requires interaction and coordination between the respiratory CPG and those governing the nonrespiratory activities. Most of these interactions are complex and poorly understood. They seem to involve both conventional synaptic crosstalk between groups of neurons and fluid identity of neurons as belonging to one CPG or another: neurons that normally participate in breathing may be temporarily borrowed or hijacked by a competing or interrupting activity. This review explores the control of breathing as it is influenced by many activities that are generally considered to be nonrespiratory. The mechanistic detail varies greatly among topics, reflecting the wide variety of pertinent experiments.

  11. Oral Breathing Challenge in Participants with Vocal Attrition

    Science.gov (United States)

    Sivasankar, Mahalakshmi; Fisher, Kimberly V.

    2003-01-01

    Vocal folds undergo osmotic challenge by mouth breathing during singing, exercising, and loud speaking. Just 15 min of obligatory oral breathing, to dry the vocal folds, increases phonation threshold pressure (P[subscript th]) and expiratory vocal effort in healthy speakers (M. Sivasankar & K. Fisher, 2002). We questioned whether oral breathing is…

  12. Human respiratory deposition of particles during oronasal breathing

    Science.gov (United States)

    Swift, David L.; Proctor, Donald F.

    Deposition of particles in the tracheobronchial and pulmonary airways is computed as a function of particle size, correcting for deposition in the parallel nasal and oral airways with oronasal breathing. Thoracic deposition is lower at all sizes for oronasal breathing than for mouth breathing via tube, and is negligible for aerodynamic equivalent diameters of 10 μm or larger.

  13. 46 CFR 197.340 - Breathing gas supply.

    Science.gov (United States)

    2010-10-01

    ... 46 Shipping 7 2010-10-01 2010-10-01 false Breathing gas supply. 197.340 Section 197.340 Shipping... GENERAL PROVISIONS Commercial Diving Operations Equipment § 197.340 Breathing gas supply. (a) A primary breathing gas supply for surface-supplied diving must be sufficient to support the following for...

  14. 46 CFR 197.312 - Breathing supply hoses.

    Science.gov (United States)

    2010-10-01

    ... 46 Shipping 7 2010-10-01 2010-10-01 false Breathing supply hoses. 197.312 Section 197.312 Shipping... GENERAL PROVISIONS Commercial Diving Operations Equipment § 197.312 Breathing supply hoses. (a) Each breathing supply hose must— (1) Have a maximum working pressure that is equal to or exceeds— (i) The...

  15. 21 CFR 868.5330 - Breathing gas mixer.

    Science.gov (United States)

    2010-04-01

    ... 21 Food and Drugs 8 2010-04-01 2010-04-01 false Breathing gas mixer. 868.5330 Section 868.5330...) MEDICAL DEVICES ANESTHESIOLOGY DEVICES Therapeutic Devices § 868.5330 Breathing gas mixer. (a) Identification. A breathing gas mixer is a device intended for use in conjunction with a respiratory...

  16. 42 CFR 84.90 - Breathing resistance test; inhalation.

    Science.gov (United States)

    2010-10-01

    ... 42 Public Health 1 2010-10-01 2010-10-01 false Breathing resistance test; inhalation. 84.90...-Contained Breathing Apparatus § 84.90 Breathing resistance test; inhalation. (a) Resistance to inhalation airflow will be measured in the facepiece or mouthpiece while the apparatus is operated by a...

  17. 42 CFR 84.122 - Breathing resistance test; minimum requirements.

    Science.gov (United States)

    2010-10-01

    ... 42 Public Health 1 2010-10-01 2010-10-01 false Breathing resistance test; minimum requirements. 84... Masks § 84.122 Breathing resistance test; minimum requirements. (a) Resistance to airflow will be measured in the facepiece or mouthpiece of a gas mask mounted on a breathing machine both before and...

  18. 46 CFR 197.450 - Breathing gas tests.

    Science.gov (United States)

    2010-10-01

    ... 46 Shipping 7 2010-10-01 2010-10-01 false Breathing gas tests. 197.450 Section 197.450 Shipping....450 Breathing gas tests. The diving supervisor shall insure that— (a) The output of each air... or modification. (b) Purchased supplies of breathing mixtures supplied to a diver are checked...

  19. 21 CFR 868.5240 - Anesthesia breathing circuit.

    Science.gov (United States)

    2010-04-01

    ... 21 Food and Drugs 8 2010-04-01 2010-04-01 false Anesthesia breathing circuit. 868.5240 Section 868...) MEDICAL DEVICES ANESTHESIOLOGY DEVICES Therapeutic Devices § 868.5240 Anesthesia breathing circuit. (a) Identification. An anesthesia breathing circuit is a device that is intended to administer medical gases to...

  20. 42 CFR 84.115 - Breathing tubes; minimum requirements.

    Science.gov (United States)

    2010-10-01

    ... 42 Public Health 1 2010-10-01 2010-10-01 false Breathing tubes; minimum requirements. 84.115 Section 84.115 Public Health PUBLIC HEALTH SERVICE, DEPARTMENT OF HEALTH AND HUMAN SERVICES OCCUPATIONAL... § 84.115 Breathing tubes; minimum requirements. Flexible breathing tubes used in conjunction with...

  1. 42 CFR 84.172 - Breathing tubes; minimum requirements.

    Science.gov (United States)

    2010-10-01

    ... 42 Public Health 1 2010-10-01 2010-10-01 false Breathing tubes; minimum requirements. 84.172... Air-Purifying Particulate Respirators § 84.172 Breathing tubes; minimum requirements. Flexible breathing tubes used in conjunction with respirators shall be designed and constructed to prevent:...

  2. Effect of slow deep breathing (6 breaths/min) on pulmonary function in healthy volunteers

    OpenAIRE

    Shravya Keerthi G, Hari Krishna Bandi, Suresh M, Mallikarjuna Reddy

    2013-01-01

    We designed this study to test the hypothesis that whether 10 minutes of slow deep breathing have any effect on pulmonary function in healthy volunteers. The main objective was to study the immediate effect of slow deep breathing on Forced vital capacity (FVC), Forced expiratory volume in the first second (FEV1), Forced expiratory volume percent (FEV1/FVC%), Peak expiratory flow rate (PEFR), Forced expiratory flow 25-75%(FEF25-75%), Maximum voluntary ventilation (MVV), Slow vital capacity (SV...

  3. Upper limb kinematic differences between breathing and non-breathing conditions in front crawl sprint swimming.

    Science.gov (United States)

    McCabe, Carla B; Sanders, Ross H; Psycharakis, Stelios G

    2015-11-26

    The purpose of this study was to determine whether the breathing action in front crawl (FC) sprint swimming affects the ipsilateral upper limb kinematics relative to a non-breathing stroke cycle (SC). Ten male competitive swimmers performed two 25m FC sprints: one breathing to their preferred side (Br) and one not breathing (NBr). Both swim trials were performed through a 6.75m(3) calibrated space and recorded by six gen-locked JVC KY32 CCD cameras. A paired t-test was used to assess statistical differences between the trials, with a confidence level of pswim performance is compromised by the inclusion of taking a breath in sprint FC swimming. It was proposed that swimmers aim to orient their ipsilateral shoulder into a stronger position by stretching and rolling the shoulders more in the entry phase whilst preparing to take a breath. Swimmers should focus on lengthening the push phase by extending the elbow more and not accelerating the hand too quickly upwards when preparing to inhale.

  4. Methodology for concurrent determination of urea kinetics and the capture of recycled urea nitrogen by ruminal microbes in cattle.

    Science.gov (United States)

    Wickersham, T A; Titgemeyer, E C; Cochran, R C

    2009-03-01

    We measured the incorporation of recycled urea-nitrogen (N) by ruminal microbes, using five ruminally and duodenally fistulated steers (237 kg) fed low-quality grass hay (47 g crude protein/kg dry matter (DM)). Three received 1 kg/day of soybean meal (SBM) and two received no supplemental protein (control). The experiment was 15 days long. Background enrichments of 15N were measured on day 9 and continuous jugular infusion of 0.12 g/day [15N15N]urea began on day 10. Daily samples of urine, feces, ruminal bacteria and duodenal digesta from days 10 through 14 were used to determine plateaus in 15N enrichment. Duodenal and bacterial samples collected on day 15 were used to measure duodenal N flows. Bacterial N flow was calculated as duodenal N flow multiplied by duodenal 15N enrichment divided by bacterial 15N enrichment. Bacterial N from recycled urea-N was calculated as bacterial N flow multiplied by bacterial 15N enrichment divided by urinary urea 15N enrichment. Urinary enrichment of [15N15N]urea plateaued within 24 h, whereas 14N15N urea plateaued within 48 h of [15N15N]urea infusion. Bacteria reached a plateau in 15N enrichment within 24 h and duodenal samples within 48 h. Urea production was 17.6 g of urea-N/day for control and 78.0 g/day for SBM. Gut entry was 0.99 g of urea-N/g of urea-N produced for control and 0.87 g/g for SBM. Incorporation of recycled N into microbial N was 9.0 g of N/day for control and 23.0 g/day for SBM. Recycled urea-N accounted for 0.33 g of N/g of microbial N at the duodenum for control and 0.27 g/g for SBM. Our methods allowed measurement of incorporation of recycled urea-N into ruminal microbial N.

  5. Efficacy of Dietary Urea-Impregnated Zeolite in Improving Rumen Fermentation Characteristics of Local Lamb

    Directory of Open Access Journals (Sweden)

    D. Kardaya

    2012-12-01

    Full Text Available A research on dietary inclusion of urea-impregnated zeolite as slow-release urea (SRU agent had been conducted to reveal its effect on ruminal fermentation characteristics in local lambs. The research used 24 heads of 7-8 mo old of local male lambs with (20.12±2.1 kg BW designed upon a randomized block design. Treatments consisted of diets contained no urea, urea, zeolite, and urea-impregnated zeolite. The collected data was analyzed with UNIANOVA and Duncan’s multiple-range test. Results indicated that feeding no urea, zeolite, or urea-impregnated zeolite ration produced lower ruminal ammonia nitrogen than feeding urea ration (P<0.05. Feeding zeolite ration produced lower ruminal pH than feeding urea ration (P<0.05. Despite total VFAs were similar across the treatments, feeding urea-impregnated zeolite ration produced lower ruminal acetate, acetate to propionate ratio, or methane production than feeding urea ration (P<0.05. Feeding urea ration produced the lowest molar proportion of branch-chained VFAs (P<0.05. Feeding urea ration produced higher plasma urea concentration than feeding no urea ration (2.75 mM vs. 2.16 mM; P<0.05. In conclusion, zeolite or urea-impregnated zeolite as slow-release ammonia or SRU agent was potential in decreasing ruminal ammonia, pH, acetate to propionate ratio, methane, and maintaining low plasma urea within its physiological range.

  6. Quantum crystallographic charge density of urea.

    Science.gov (United States)

    Wall, Michael E

    2016-07-01

    Standard X-ray crystallography methods use free-atom models to calculate mean unit-cell charge densities. Real molecules, however, have shared charge that is not captured accurately using free-atom models. To address this limitation, a charge density model of crystalline urea was calculated using high-level quantum theory and was refined against publicly available ultra-high-resolution experimental Bragg data, including the effects of atomic displacement parameters. The resulting quantum crystallographic model was compared with models obtained using spherical atom or multipole methods. Despite using only the same number of free parameters as the spherical atom model, the agreement of the quantum model with the data is comparable to the multipole model. The static, theoretical crystalline charge density of the quantum model is distinct from the multipole model, indicating the quantum model provides substantially new information. Hydrogen thermal ellipsoids in the quantum model were very similar to those obtained using neutron crystallography, indicating that quantum crystallography can increase the accuracy of the X-ray crystallographic atomic displacement parameters. The results demonstrate the feasibility and benefits of integrating fully periodic quantum charge density calculations into ultra-high-resolution X-ray crystallographic model building and refinement.

  7. Quantum crystallographic charge density of urea

    Science.gov (United States)

    Wall, Michael E.

    2016-01-01

    Standard X-ray crystallography methods use free-atom models to calculate mean unit-cell charge densities. Real molecules, however, have shared charge that is not captured accurately using free-atom models. To address this limitation, a charge density model of crystalline urea was calculated using high-level quantum theory and was refined against publicly available ultra-high-resolution experimental Bragg data, including the effects of atomic displacement parameters. The resulting quantum crystallographic model was compared with models obtained using spherical atom or multipole methods. Despite using only the same number of free parameters as the spherical atom model, the agreement of the quantum model with the data is comparable to the multipole model. The static, theoretical crystalline charge density of the quantum model is distinct from the multipole model, indicating the quantum model provides substantially new information. Hydrogen thermal ellipsoids in the quantum model were very similar to those obtained using neutron crystallography, indicating that quantum crystallography can increase the accuracy of the X-ray crystallographic atomic displacement parameters. The results demonstrate the feasibility and benefits of integrating fully periodic quantum charge density calculations into ultra-high-resolution X-ray crystallographic model building and refinement. PMID:27437111

  8. Quantum crystallographic charge density of urea

    Directory of Open Access Journals (Sweden)

    Michael E. Wall

    2016-07-01

    Full Text Available Standard X-ray crystallography methods use free-atom models to calculate mean unit-cell charge densities. Real molecules, however, have shared charge that is not captured accurately using free-atom models. To address this limitation, a charge density model of crystalline urea was calculated using high-level quantum theory and was refined against publicly available ultra-high-resolution experimental Bragg data, including the effects of atomic displacement parameters. The resulting quantum crystallographic model was compared with models obtained using spherical atom or multipole methods. Despite using only the same number of free parameters as the spherical atom model, the agreement of the quantum model with the data is comparable to the multipole model. The static, theoretical crystalline charge density of the quantum model is distinct from the multipole model, indicating the quantum model provides substantially new information. Hydrogen thermal ellipsoids in the quantum model were very similar to those obtained using neutron crystallography, indicating that quantum crystallography can increase the accuracy of the X-ray crystallographic atomic displacement parameters. The results demonstrate the feasibility and benefits of integrating fully periodic quantum charge density calculations into ultra-high-resolution X-ray crystallographic model building and refinement.

  9. Predictive model for segmented poly(urea

    Directory of Open Access Journals (Sweden)

    Frankl P.

    2012-08-01

    Full Text Available Segmented poly(urea has been shown to be of significant benefit in protecting vehicles from blast and impact and there have been several experimental studies to determine the mechanisms by which this protective function might occur. One suggested route is by mechanical activation of the glass transition. In order to enable design of protective structures using this material a constitutive model and equation of state are needed for numerical simulation hydrocodes. Determination of such a predictive model may also help elucidate the beneficial mechanisms that occur in polyurea during high rate loading. The tool deployed to do this has been Group Interaction Modelling (GIM – a mean field technique that has been shown to predict the mechanical and physical properties of polymers from their structure alone. The structure of polyurea has been used to characterise the parameters in the GIM scheme without recourse to experimental data and the equation of state and constitutive model predicts response over a wide range of temperatures and strain rates. The shock Hugoniot has been predicted and validated against existing data. Mechanical response in tensile tests has also been predicted and validated.

  10. First Breath prenatal smoking cessation pilot study: preliminary findings.

    Science.gov (United States)

    Jehn, Lisette; Lokker, Nicole; Matitz, Debra; Christiansen, Bruce

    2003-01-01

    Despite the many dangers associated with smoking during pregnancy, it remains a salient public health problem for Wisconsin women. The First Breath pilot program was developed in an attempt to reduce rates of smoking during pregnancy among low-income women. Preliminary results suggest that the First Breath counseling-based approach is effective, with a quit rate of 43.8% among First Breath enrollees at 1 month postpartum. Women receiving First Breath cessation counseling also had higher quit rates at every measurement period versus women in a comparison group who were receiving whatever cessation care was available in their county in the absence of First Breath. The First Breath pilot study has demonstrated success in helping pregnant women quit smoking and in creating a model for integration of cessation services into prenatal health care service provision. It is through this success that First Breath is expanding beyond the pilot study stage to a statewide program in 2003.

  11. Information dynamics in cardiorespiratory analyses: application to controlled breathing.

    Science.gov (United States)

    Widjaja, Devy; Faes, Luca; Montalto, Alessandro; Van Diest, Ilse; Marinazzo, Daniele; Van Huffel, Sabine

    2014-01-01

    Voluntary adjustment of the breathing pattern is widely used to deal with stress-related conditions. In this study, effects of slow and fast breathing with a low and high inspiratory to expiratory time on heart rate variability (HRV) are evaluated by means of information dynamics. Information transfer is quantified both as the traditional transfer entropy as well as the cross entropy, where the latter does not condition on the past of HRV, thereby taking the highly unidirectional relation between respiration and heart rate into account. The results show that the cross entropy is more suited to quantify cardiorespiratory information transfer as this measure increases during slow breathing, indicating the increased cardiorespiratory coupling and suggesting the shift towards vagal activation during slow breathing. Additionally we found that controlled breathing, either slow or fast, results as well in an increase in cardiorespiratory coupling, compared to spontaneous breathing, which demonstrates the beneficial effects of instructed breathing.

  12. Breathing pattern, thoracoabdominal motion and muscular activity during three breathing exercises

    Directory of Open Access Journals (Sweden)

    G.M. Tomich

    2007-10-01

    Full Text Available The objective of the present study was to evaluate breathing pattern, thoracoabdominal motion and muscular activity during three breathing exercises: diaphragmatic breathing (DB, flow-oriented (Triflo II incentive spirometry and volume-oriented (Voldyne incentive spirometry. Seventeen healthy subjects (12 females, 5 males aged 23 ± 5 years (mean ± SD were studied. Calibrated respiratory inductive plethysmography was used to measure the following variables during rest (baseline and breathing exercises: tidal volume (Vt, respiratory frequency (f, rib cage contribution to Vt (RC/Vt, inspiratory duty cycle (Ti/Ttot, and phase angle (PhAng. Sternocleidomastoid muscle activity was assessed by surface electromyography. Statistical analysis was performed by ANOVA and Tukey or Friedman and Wilcoxon tests, with the level of significance set at P < 0.05. Comparisons between baseline and breathing exercise periods showed a significant increase of Vt and PhAng during all exercises, a significant decrease of f during DB and Voldyne, a significant increase of Ti/Ttot during Voldyne, and no significant difference in RC/Vt. Comparisons among exercises revealed higher f and sternocleidomastoid activity during Triflo II (P < 0.05 with respect to DB and Voldyne, without a significant difference in Vt, Ti/Ttot, PhAng, or RC/Vt. Exercises changed the breathing pattern and increased PhAng, a variable of thoracoabdominal asynchrony, compared to baseline. The only difference between DB and Voldyne was a significant increase of Ti/Ttot compared to baseline. Triflo II was associated with higher f values and electromyographic activity of the sternocleidomastoid. In conclusion, DB and Voldyne showed similar results while Triflo II showed disadvantages compared to the other breathing exercises.

  13. Breath Analysis Using Laser Spectroscopic Techniques: Breath Biomarkers, Spectral Fingerprints, and Detection Limits

    Directory of Open Access Journals (Sweden)

    Peeyush Sahay

    2009-10-01

    Full Text Available Breath analysis, a promising new field of medicine and medical instrumentation, potentially offers noninvasive, real-time, and point-of-care (POC disease diagnostics and metabolic status monitoring. Numerous breath biomarkers have been detected and quantified so far by using the GC-MS technique. Recent advances in laser spectroscopic techniques and laser sources have driven breath analysis to new heights, moving from laboratory research to commercial reality. Laser spectroscopic detection techniques not only have high-sensitivity and high-selectivity, as equivalently offered by the MS-based techniques, but also have the advantageous features of near real-time response, low instrument costs, and POC function. Of the approximately 35 established breath biomarkers, such as acetone, ammonia, carbon dioxide, ethane, methane, and nitric oxide, 14 species in exhaled human breath have been analyzed by high-sensitivity laser spectroscopic techniques, namely, tunable diode laser absorption spectroscopy (TDLAS, cavity ringdown spectroscopy (CRDS, integrated cavity output spectroscopy (ICOS, cavity enhanced absorption spectroscopy (CEAS, cavity leak-out spectroscopy (CALOS, photoacoustic spectroscopy (PAS, quartz-enhanced photoacoustic spectroscopy (QEPAS, and optical frequency comb cavity-enhanced absorption spectroscopy (OFC-CEAS. Spectral fingerprints of the measured biomarkers span from the UV to the mid-IR spectral regions and the detection limits achieved by the laser techniques range from parts per million to parts per billion levels. Sensors using the laser spectroscopic techniques for a few breath biomarkers, e.g., carbon dioxide, nitric oxide, etc. are commercially available. This review presents an update on the latest developments in laser-based breath analysis.

  14. Urea determination using pH-enzyme electrode.

    Science.gov (United States)

    Koncki, R; Chudzik, A; Walcerz, I

    1999-10-01

    A pH-membrane electrode with n-tridodecylamine (TDDA) as the hydrogen-ion-selective ionophore was used for the construction of a potentiometric biosensor for urea determination. The electrode was enzymatically modified by covalent binding of urease molecules directly to the surface of the potentiometric membrane. Incorporation of the urea biosensor into simple double-channel flow injection analysis (FIA) system allows reproducible urea determination in a millimolar range of concentration. The utility and limitations of the presented biosensor-FIA system for analysis of various real samples has been investigated. The system can be useful for some biomedical and pharmaceutical applications such as analyses of urine, posthaemodialysis fluid and extracts from pharmaceutical ointments containing urea.

  15. Influence of Ficoll on urea induced denaturation of fibrinogen

    Science.gov (United States)

    Sankaranarayanan, Kamatchi; Meenakshisundaram, N.

    2016-03-01

    Ficoll is a neutral, highly branched polymer used as a molecular crowder in the study of proteins. Ficoll is also part of Ficoll-Paque used in biology laboratories to separate blood to its components (erythrocytes, leukocytes etc.,). Role of Ficoll in the urea induced denaturation of protein Fibrinogen (Fg) has been analyzed using fluorescence, circular dichroism, molecular docking and interfacial studies. Fluorescence studies show that Ficoll prevents quenching of Fg in the presence of urea. From the circular dichroism spectra, Fg shows conformational transition to random coil with urea of 6 M concentration. Ficoll helps to shift this denaturation concentration to 8 M and thus constraints by shielding Fg during the process. Molecular docking studies indicate that Ficoll interacts favorably with the protein than urea. The surface tension and shear viscosity analysis shows clearly that the protein is shielded by Ficoll.

  16. Uranium stripping from tributyl phosphate by urea solutions

    Science.gov (United States)

    Skripchenko, S. Yu.; Titova, S. M.; Smirnov, A. L.; Rychkov, V. N.

    2016-09-01

    The process of uranium stripping from tri-n-butyl phosphate in kerosene by urea solutions was investigated at the volume ratio of the organic and aqueous phases of (1-10) : 1 in the temperature range of 20-60 °C. The stripping of uranium from a loaded organic phase increased with increasing urea content in the solution and with increasing temperature. Maximum recovery of uranium from tributyl phosphate was obtained using a solution that contained 8-12 mol/l of urea. The application of a urea solution for uranium stripping resulted in the strip product solution containing 200-240 g/L of uranium. The process of uranium stripping by dilute nitric acid was also investigated. Results of uranium stripping by the two methods are compared and discussed.

  17. Deprotection of oximes using urea nitrate under microwave irradiation

    Indian Academy of Sciences (India)

    P T Perumal; M Anniyappan; D Muralidharan

    2004-08-01

    A new mild and efficient method for the cleavage of oximes to carbonyl compounds using readily available urea nitrate in acetonitrile-water (95 : 5), under microwave irradiation within 2 min, in good yields is reported.

  18. Highly sensitive urea sensing with ion-irradiated polymer foils

    Energy Technology Data Exchange (ETDEWEB)

    Fink, Dietmar, E-mail: fink@daad-alumni.de [Departamento de Fisica, Universidad Autonoma Metropolitana-Iztapalapa, P.O. Box 55-534, 09340 Mexico, D.F. (Mexico); Nuclear Physics Institute, Academy of Sciences of the Czech Republic, 250 68 Rez (Czech Republic); Munoz Hernandez, Gerardo [Departamento de Fisica, Universidad Autonoma Metropolitana-Iztapalapa, P.O. Box 55-534, 09340 Mexico, D.F. (Mexico); Division de Ciencias Naturales e Ingenieria, Universidad Autonoma Metropolitana-Cuajimalpa, Pedro Antonio de los Santos 84, Col. Sn. Miguel Chapultepec, C.P. 11850, Mexico, D.F. (Mexico); Alfonta, Lital, E-mail: alfontal@bgu.ac.il [Avram and Stella Goldstein-Goren Department of Biotechnology Engineering, Ben-Gurion University of the Negev, P.O. Box 653, Beer-Sheva 84105 (Israel)

    2012-02-15

    Recently we prepared urea-sensors by attaching urease to the inner walls of etched ion tracks within thin polymer foil. Here, alternative track-based sensor configurations are examined where the enzyme remained in solution. The conductivities of systems consisting of two parallel irradiated polymer foils and confining different urea/urease mixtures in between were examined. The correlations between conductivity and urea concentration differed strongly for foils with unetched and etched tracks, which points at different sensing mechanisms - tentatively attributed to the adsorption of enzymatic reaction products on the latent track entrances and to the enhanced conductivity of reaction product-filled etched tracks, respectively. All examined systems enable in principle, urea sensing. They point at the possibility of sensor cascade construction for more sensitive or selective sensor systems.

  19. Breathing dissipative solitons in optical microresonators

    CERN Document Server

    Lucas, Erwan; Guo, Hairun; Gorodetsky, Michael; Kippenberg, Tobias

    2016-01-01

    Dissipative solitons are self-localized structures resulting from a double balance between dispersion and nonlinearity as well as dissipation and a driving force. They occur in a wide variety of fields ranging from optics, hydrodynamics to chemistry and biology. Recently, significant interest has focused on their temporal realization in driven optical microresonators, known as dissipative Kerr solitons. They provide access to coherent, chip-scale optical frequency combs, which have already been employed in optical metrology, data communication and spectroscopy. Such Kerr resonator systems can exhibit numerous localized intracavity patterns and provide rich insights into nonlinear dynamics. A particular class of solutions consists of breathing dissipative solitons, representing pulses with oscillating amplitude and duration, for which no comprehensive understanding has been presented to date. Here, we observe and study single and multiple breathing dissipative solitons in two different microresonator platforms...

  20. Protective supplied-breathing-air garment

    Science.gov (United States)

    Childers, E.L.; von Hortenau, E.F.

    1982-05-28

    A breathing-air garment for isolating a wearer from hostile environments containing toxins or irritants is disclosed. The garment includes a suit and a separate head-protective enclosure or hood engaging a suit collar in sealing attachment. The hood and suit collar are cylindrically shaped and dimensioned to enable the wearer to withdraw his hands from the suit sleeves to perform manual tasks within the hood interior. Breathing air is supplied from an external air line with an air-delivery hose attached to the hood interior. The hose feeds air into an annular halo-like fiber-filled plenum having spaced discharge orifices attached to the hood top wall. A plurality of air exhaust/check valves located at the suit extremities cooperate with the hood air-delivery system to provide a cooling flow of circulating air from the hood throughout the suit interior. A suit entry seal provided on the suit sealed with an adhesive sealing flap.

  1. Exploring the cocrystallization potential of urea and benzamide.

    Science.gov (United States)

    Cysewski, Piotr; Przybyłek, Maciej; Ziółkowska, Dorota; Mroczyńska, Karina

    2016-05-01

    The cocrystallization landscape of benzamide and urea interacting with aliphatic and aromatic carboxylic acids was studied both experimentally and theoretically. Ten new cocrystals of benzamide were synthesized using an oriented samples approach via a fast dropped evaporation technique. Information about types of known bi-component cocrystals augmented with knowledge of simple binary eutectic mixtures was used for the analysis of virtual screening efficiency among 514 potential pairs involving aromatic carboxylic acids interacting with urea or benzamide. Quantification of intermolecular interaction was achieved by estimating the excess thermodynamic functions of binary liquid mixtures under supercooled conditions within a COSMO-RS framework. The smoothed histograms suggest that slightly more potential pairs of benzamide are characterized in the attractive region compared to urea. Finally, it is emphasized that prediction of cocrystals of urea is fairly direct, while it remains ambiguous for benzamide paired with carboxylic acids. The two known simple eutectics of urea are found within the first two quartiles defined by excess thermodynamic functions, and all known cocrystals are outside of this range belonging to the third or fourth quartile. On the contrary, such a simple separation of positive and negative cases of benzamide miscibility in the solid state is not observed. The difference in properties between urea and benzamide R2,2(8) heterosynthons is also documented by alterations of substituent effects. Intermolecular interactions of urea with para substituted benzoic acid analogues are stronger compared to those of benzamide. Also, the amount of charge transfer from amide to aromatic carboxylic acid and vice versa is more pronounced for urea. However, in both cases, the greater the electron withdrawing character of the substituent, the higher the binding energy, and the stronger the supermolecule polarization via the charge transfer mechanism.

  2. Digestibility of pelleted rations containing diverse potato flour and urea

    Directory of Open Access Journals (Sweden)

    Isabel Martinele

    2015-11-01

    Full Text Available The aim of this study was to evaluate ruminal in situ degradability and in vitro digestibility of dry matter (DM in concentrate supplements containing diverse potato flour pelletized with urea (0%, 4%, 8%, and 12% DM. Samples of feeds were incubated for 0, 2, 4, 8, 12, 24, 36, and 48h in the rumen of four fistulated sheep. Level of urea added had no significant effect (P>;0.05 on the soluble fraction (a or potentially degradable fraction (b of the pellets and ranged from 2.1% to 12.2% and 72.9% to 87.5%, respectively. Quadratic effects (P=0.03 of the rate of degradation of fraction "b" ranged from 4.75% h-1to 7.39% h-1; the estimated maximum value at 7.4% h-1was obtained when 5.9% urea was added to the pellet. Quadratic effects (P≤0.02 of the level of urea added to the pellets on the effective degradability (ED of DM were evaluated after considering rumen passage rates of 2.5% h-1and 8% h-1; the maximum values of ED calculated under these rumen passage rates were estimated at 6.3% to 7.3% urea in the pellets. The in vitro digestibility of DM of the pellets showed a quadratic effect (P=0.02 at different levels of urea, with a maximum value of 96.9% achieved when 7.9% urea was added to the pellets. Our results suggest that the addition of 6-8% urea to pelleted feed promotes an increase in the in vitro digestibility and ED of DM.

  3. C-130J Breathing Resistance Study

    Science.gov (United States)

    2016-05-01

    flows used in the study . The simulated workloads were: 1) 60 ALPM: Rest; 2) 90 ALPM: Light Work ; 3) 125 ALPM: Moderate Work ; and 4) 150 ALPM...AFRL-RH-WP-TR-2016-0040 C-130J BREATHING RESISTANCE STUDY George W. Miller Air Force Research Laboratory Wright-Patterson Air...ASSIGNED DISTRIBUTION STATEMENT. //signed// //signed// GEORGE W. MILLER SCOTT M. GALSTER Work Unit Manager Chief, Applied

  4. NiO nanoparticle-based urea biosensor.

    Science.gov (United States)

    Tyagi, Manisha; Tomar, Monika; Gupta, Vinay

    2013-03-15

    NiO nanoparticles (NiO-NPs) have been exploited successfully for the fabrication of a urea biosensor. A thin film of NiO nanoparticles deposited on an indium tin oxide (ITO) coated glass substrate serves as an efficient matrix for the immobilisation of urease (Ur), the specific enzyme for urea detection. The prepared bioelectrode (Ur/NiO-NP/ITO/glass) is utilised for urea sensing using cyclic voltammetry and UV-visible spectroscopy. NiO nanoparticles act as electro-catalytic species that are based on the shuttling of electrons between Ni(2+) and Ni(3+) in the octahedral site and result in an enhanced electrochemical current response. The prepared bioelectrode (Ur/NiO-NPs/ITO/glass) exhibits a high sensitivity of 21.3 μA/(mM (*) cm(2)) and a good linearity in a wide range (0.83-16.65 Mm) of urea concentrations with fast response time of 5s. The low value of the Michaelis-Menten constant (K(m)=0.34 mM) indicates the high affinity of Ur towards the analyte (urea). The high catalytic activity, along with the redox behaviour of NiO-NPs, makes it an efficient matrix for the realisation of a urea biosensor.

  5. Discovery of enantioselectivity of urea inhibitors of soluble epoxide hydrolase.

    Science.gov (United States)

    Manickam, Manoj; Pillaiyar, Thanigaimalai; Boggu, PullaReddy; Venkateswararao, Eeda; Jalani, Hitesh B; Kim, Nam-Doo; Lee, Seul Ki; Jeon, Jang Su; Kim, Sang Kyum; Jung, Sang-Hun

    2016-07-19

    Soluble epoxide hydrolase (sEH) hydrolyzes epoxyeicosatrienoic acids (EETs) in the metabolic pathway of arachidonic acid and has been considered as an important therapeutic target for chronic diseases such as hypertension, diabetes and inflammation. Although many urea derivatives are known as sEH inhibitors, the enantioselectivity of the inhibitors is not highlighted in spite of the stereoselective hydrolysis of EETs by sEH. In an effort to explore the importance of enantioselectivity in the urea scaffold, a series of enantiomers with the stereocenter adjacent to the urea nitrogen atom were prepared. The selectivity of enantiomers of 1-(α-alkyl-α-phenylmethyl)-3-(3-phenylpropyl)ureas showed wide range differences up to 125 fold with the low IC50 value up to 13 nM. The S-configuration with planar phenyl and small alkyl groups at α-position is crucial for the activity and selectivity. However, restriction of the free rotation of two α-groups with indan-1-yl or 1,2,3,4-tetrahydronaphthalen-1-yl moiety abolishes the selectivity between the enantiomers, despite the increase in activity up to 13 nM. The hydrophilic group like sulfonamido group at para position of 3-phenylpropyl motif of 1-(α-alkyl-α-phenylmethyl-3-(3-phenylpropyl)urea improves the activity as well as enantiomeric selectivity. All these ureas are proved to be specific inhibitor of sEH without inhibition against mEH.

  6. Urea-induced oxidative damage in Elodea densa leaves.

    Science.gov (United States)

    Maleva, Maria; Borisova, Galina; Chukina, Nadezda; Prasad, M N V

    2015-09-01

    Urea being a fertilizer is expected to be less toxic to plants. However, it was found that urea at 100 mg L(-1) caused the oxidative stress in Elodea leaves due to the formation of reactive oxygen species (ROS) and lipid peroxidation that are known to stimulate antioxidant pathway. Urea at a concentration of 500 and 1000 mg L(-1) decreased low-molecular-weight antioxidants. In this case, the antioxidant status of plants was supported by the activity of antioxidant enzymes such as superoxide dismutase and guaiacol peroxidase. A significant increase in the soluble proteins and -SH groups was observed with high concentrations of urea (30-60 % of control). Thus, the increased activity of antioxidant enzymes, low-molecular-weight antioxidants, and induced soluble protein thiols are implicated in plant resistance to oxidative stress imposed by urea. We found that guaiacol peroxidase plays an important role in the removal of the peroxide in Elodea leaves exposed to 1000 mg L(-1)of urea.

  7. Active urea transport in lower vertebrates and mammals.

    Science.gov (United States)

    Bankir, Lise

    2014-01-01

    Some unicellular organisms can take up urea from the surrounding fluids by an uphill pumping mechanism. Several active (energy-dependent) urea transporters (AUTs) have been cloned in these organisms. Functional studies show that active urea transport also occurs in elasmobranchs, amphibians, and mammals. In the two former groups, active urea transport may serve to conserve urea in body fluids in order to balance external high ambient osmolarity or prevent desiccation. In mammals, active urea transport may be associated with the need to either store and/or reuse nitrogen in the case of low nitrogen supply, or to excrete nitrogen efficiently in the case of excess nitrogen intake. There are probably two different families of AUTs, one with a high capacity able to establish only a relatively modest transepithelial concentration difference (renal tubule of some frogs, pars recta of the mammalian kidney, early inner medullary collecting duct in some mammals eating protein-poor diets) and others with a low capacity but able to maintain a high transepithelial concentration difference that has been created by another mechanism or in another organ (elasmobranch gills, ventral skin of some toads, and maybe mammalian urinary bladder). Functional characterization of these transporters shows that some are coupled to sodium (symports or antiports) while others are sodium-independent. In humans, only one genetic anomaly, with a mild phenotype (familial azotemia), is suspected to concern one of these transporters. In spite of abundant functional evidence for such transporters in higher organisms, none have been molecularly identified yet.

  8. Breath alcohol, multisensor arrays, and electronic noses

    Science.gov (United States)

    Paulsson, Nils; Winquist, Fredrik

    1997-01-01

    The concept behind a volatile compound mapper, or electronic nose, is to use the combination of multiple gas sensors and pattern recognition techniques to detect and quantify substances in gas mixtures. There are several different kinds of sensors which have been developed during recent years of which the base techniques are conducting polymers, piezo electrical crystals and solid state devices. In this work we have used a combination of gas sensitive field effect devices and semiconducting metal oxides. The most useful pattern recognition routine was found to be ANNs, which is a mathematical approximation of the human neural network. The aim of this work is to evaluate the possibility of using electronic noses in field instruments to detect drugs, arson residues, explosives etc. As a test application we have chosen breath alcohol measurements. There are several reasons for this. Breath samples are a quite complex mixture contains between 200 and 300 substances at trace levels. The alcohol level is low but still possible to handle. There are needs for replacing large and heavy mobile instruments with smaller devices. Current instrumentation is rather sensitive to interfering substances. The work so far has dealt with sampling, how to introduce ethanol and other substances in the breath, correlation measurements between the electronic nose and headspace GC, and how to evaluate the sensor signals.

  9. Determination of breath isoprene allows the identification of the expiratory fraction of the propofol breath signal during real-time propofol breath monitoring.

    Science.gov (United States)

    Hornuss, Cyrill; Dolch, Michael E; Janitza, Silke; Souza, Kimberly; Praun, Siegfried; Apfel, Christian C; Schelling, Gustav

    2013-10-01

    Real-time measurement of propofol in the breath may be used for routine clinical monitoring. However, this requires unequivocal identification of the expiratory phase of the respiratory propofol signal as only expiratory propofol reflects propofol blood concentrations. Determination of CO2 breath concentrations is the current gold standard for the identification of expiratory gas but usually requires additional equipment. Human breath also contains isoprene, a volatile organic compound with low inspiratory breath concentration and an expiratory concentration plateau. We investigated whether breath isoprene could be used similarly to CO2 to identify the expiratory fraction of the propofol breath signal. We investigated real-time breath data obtained from 40 study subjects during routine anesthesia. Propofol, isoprene, and CO2 breath concentrations were determined by a combined ion molecule reaction/electron impact mass spectrometry system. The expiratory propofol signal was identified according to breath CO2 and isoprene concentrations and presented as median of intervals of 30 s duration. Bland-Altman analysis was applied to detect differences (bias) in the expiratory propofol signal extracted by the two identification methods. We investigated propofol signals in a total of 3,590 observation intervals of 30 s duration in the 40 study subjects. In 51.4 % of the intervals (1,844/3,590) both methods extracted the same results for expiratory propofol signal. Overall bias between the two data extraction methods was -0.12 ppb. The lower and the upper limits of the 95 % CI were -0.69 and 0.45 ppb. Determination of isoprene breath concentrations allows the identification of the expiratory propofol signal during real-time breath monitoring.

  10. Radiopaque, iodine functionalized, phenylalanine-based poly(ester urea)s.

    Science.gov (United States)

    Li, Shan; Yu, Jiayi; Wade, Mary Beth; Policastro, Gina M; Becker, Matthew L

    2015-02-01

    The synthesis and characterization of iodine-functionalized phenylalanine-based poly(ester urea)s (PEUs) are reported. 4-Iodo-L-phenylalanine and L-phenylalanine were separately reacted with 1,6-hexanediol to produce two monomers, bis-4-I-L-phenylalanine-1,6-hexanediol-diester (1-IPHE-6 monomer) and bis-L-phenylalanine-1,6-hexanediol-diester (1-PHE-6 monomer). By varying the feed ratio of the 1-IPHE-6 and 1-PHE-6 monomers, the copolymer composition was modulated resulting in a wide variation in thermal, mechanical and radiopacity properties. Microcomputed tomography (μ-CT) projections demonstrate that increasing iodine content results in greater X-ray contrast. Compression tests of dry and wet porous scaffolds indicate that the poly(1-IPHE-6)0.24-co-poly(1-PHE-6)0.76 material results in the highest compression modulus. MC3T3 cell viability and spreading studies show PEUs are nontoxic to cells. As most medical device procedures require placement verification via fluoroscopic imaging, materials that possess inherent X-ray contrast are valuable for a number of applications.

  11. Fast-starting for a breath: Air breathing in Hoplosternum littorale

    DEFF Research Database (Denmark)

    Steffensen, John Fleng

    2012-01-01

    overlap considerably in their kinematics (turning rates and distance covered), suggesting that air breathing in this species is performed using escapelike C-start motions. This demonstrates that C-starts in fish do not need external stimulation and can be spontaneous behaviours used outside the context...... to be food-related. Little is known about C-starts being used outside the context of escaping or feeding. Here, we test the hypothesis that air-breathing fish may use C-starts when gulping air at the surface. Air breathing is a common behaviour in many fish species when exposed to hypoxia, although certain...... of Denmark, Denmark), John F. Steffensen (University of Copenhagen, Denmark), Morten Svendsen (Technical University of Denmark, Denmark) and Augusto Abe (Unlversidade Estadual Paulista, Brazil) Fast starts are brief accelerations commonly observed in fish within the context of predator-prey interactions...

  12. Effect of Urea Concentration on the Viscosity and Thermal Stability of Aqueous NaOH/Urea Cellulose Solutions

    Directory of Open Access Journals (Sweden)

    Tim Huber

    2016-01-01

    Full Text Available Aqueous solutions of sodium hydroxide (NaOH and urea are a known and versatile solvent for cellulose. The dissolution of cellulose occurs at subambient temperatures through the formation of a cellulose-NaOH-urea “inclusion complex” (IC. NaOH and urea form a hydrate layer around the cellulose chains preventing chain agglomeration. Urea is known to stabilize the solution but its direct role is unknown. Using viscometry and quartz crystal microbalance with dissipation monitoring (QCM-D it could be shown that the addition of urea reduced the solutions viscosity of the tested solutions by almost 40% and also increased the gelation temperature from approximately 40°C to 90°C. Both effects could also be observed in the presence of additional cellulose powder serving as a physical cross-linker. Using Fourier transform infrared (FTIR spectroscopy during heating, it could be shown that a direct interaction occurs between urea and the cellulose molecules, reducing their ability to form hydrogen bonds with neighbouring chains.

  13. Preparation of Urea Nitrogen Adsorbent of Complex Type and Adsorption Capacity of Urea Nitrogen onto the Adsorbent

    Institute of Scientific and Technical Information of China (English)

    2006-01-01

    The urea nitroge n adsorbent of complex type, which consists of chitosan coated dialdehyde cellulose (CDAC) and immobilized urease in gelatin membrane (IE), was prepared. The cellulose, the dialdehyde cellulose (DAC) and the CDAC were characterized by scanning electronic microscope. The results indicate that the cellulose C2-C3 bond was broken under the oxidation of periodate and it was oxidated to DAC. The DAC was coated with chitosan and the CDAC was obtained. The adsorption of urea nitrogen onto the adsorbent in Na2HPO4-NaH2PO4 buffer solution was studied in batch system. The effects of the experiment parameters, including degree of oxidation of CDAC, initial urea nitrogen concentration, pH and temperature, on the adsorption capacity of urea nitrogen onto the adsorbent at CDAC/IE weight ratio 10:1 were investigated. The results indicate that these parameters affected significantly the adsorption capacity. The adsorption capacity of urea nitrogen onto the adsorbent was 36.7 mg/g at the degree of oxidation of CDAC 88%, initial urea nitrogen concentration 600 mg/L, pH 7.4 and temperature 37 ℃.

  14. Molecular hydrogen in human breath: a new strategy for selectively diagnosing peptic ulcer disease, non-ulcerous dyspepsia and Helicobacter pylori infection.

    Science.gov (United States)

    Maity, Abhijit; Pal, Mithun; Maithani, Sanchi; Ghosh, Barnali; Chaudhuri, Sujit; Pradhan, Manik

    2016-07-22

    The gastric pathogen Helicobacter pylori utilizes molecular hydrogen (H2) as a respiratory substrate during colonization in the gastric mucosa. However, the link between molecular H2 and the pathogenesis of peptic-ulcer disease (PUD) and non-ulcerous dyspepsia (NUD) by the enzymatic activity of H. pylori still remains mostly unknown. Here we provide evidence that breath H2 excretion profiles are distinctly altered by the enzymatic activity of H. pylori for individuals with NUD and PUD. We subsequently unravelled the potential molecular mechanisms responsible for the alteration of H2 in exhaled breath in association with peptic ulcers, encompassing both gastric and duodenal ulcers, along with NUD. We also established that carbon-isotopic fractionations in the acid-mediated bacterial environment regulated by bacterial urease activity cannot discriminate the actual disease state i.e. whether it is peptic ulcer or NUD. However, our findings illuminate the unusual molecular H2 in breath that can track the precise evolution of PUD and NUD, even after the eradication of H. pylori infection. This deepens our understanding of the pathophysiology of PUD and NUD, reveals non-invasively the actual disease state in real-time and thus offers a novel and robust new-generation strategy for treating peptic-ulcer disease together with non-ulcer related complications even when the existing (13)C-urea breath test ((13)C-UBT) fails to diagnose.

  15. Metabolic Induction of Lactic Acid Bacteria for Urea Removal

    Institute of Scientific and Technical Information of China (English)

    ZHANG Su-ai; BAI Yu; LI Dong-xia; CHEN Bo-li; SONG Cun-jiang; QIAO Ming-qiang; KONG De-ling; YU Yao-ting

    2009-01-01

    Objective:This study aims to induce nonpathogenic bacteria for urea removal as a potential treatment in renal failure. Methods:Lactococus lactis MG1363 was induced by repeated exposure to urea-rich culture media, the ability to remove urea from the media was evaluated. The effect of gastroenteric environment, such as low pH, bile salt and antiagonistic properties were investigated.The antimicrobial activities on pathogenic E.coli and S.aureus in the intestinal tract and the antibiotic tolerance of the induced bacteria were also studied.Results: Induced bacteria of 50 generations could decrease the urea level from 40.01 mg/dL to 32.99 mg/dL after 24 h. The bacteria could grow after treatment at pH3.0 for 2 h and in 0.1% bile salt for 6 h, and the urea removal activity was retained in such simulated gastroenteric environment. The removal of urea was significantly enhanced to 35.8% by addition of Ni2+ to the culture medium at neutral pH. It was also found that the induced bacteria could inhibit the growth of E.coli and S.aureus, and tolerate ampicillin,gentamicin,roxithromycin,tetracycline and cefradine. The safety tests were performed by feeding normal rats with either Lactococus lactis MG1363 or induced Lactococus lactis MG1363. The two materials did not cause any changes in blood cells, blood biochemical indexes and body weight. Conclusion: These results suggest that the induced Lactococus lactis MG1363 has the potential as an oral therapy for the removal of urea in patients with renal failure.

  16. Evaluation of carbon-14 (C{sup 14}) levels of terrestrial and marine food products of the environment of the site of Cogema La Hague; Evaluation des niveaux de carbone-14 ({sup 14}C) des denrees alimentaires terrestres et marines de l'environnement du site de COGEMA - La Hague

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    2006-04-15

    This evaluation has for object to inform about the levels in carbon 14 in the environment of the factories of La Hague. Two sectors were differentiated on one hand the terrestrial environment, and on the other hand the marine environment. The investigations concerned first and foremost food products stemming as the vegetable culture (vegetables) or individual breeding (milk, eggs) but also foodstuffs stemming from the local agriculture (cereal). In touch with the second sector, the marine environment, the sampling concerned the accessible products of the sea by all and those locally marketed (fishes, molluscs, shellfishes). The different results are presented in tables. (N.C.)

  17. Apparatus and method for monitoring breath acetone and diabetic diagnostics

    Science.gov (United States)

    Duan, Yixiang; Cao, Wenqing

    2008-08-26

    An apparatus and method for monitoring diabetes through breath acetone detection and quantitation employs a microplasma source in combination with a spectrometer. The microplasma source provides sufficient energy to produce excited acetone fragments from the breath gas that emit light. The emitted light is sent to the spectrometer, which generates an emission spectrum that is used to detect and quantify acetone in the breath gas.

  18. Development of Techniques for Trace Gas Detection in Breath

    OpenAIRE

    2012-01-01

    This thesis aims to investigate the possibility of developing spectroscopic techniques for trace gas detection, with particular emphasis on their applicability to breath analysis and medical diagnostics. Whilst key breath molecules such as methane and carbon dioxide will feature throughout this work, the focus of the research is on the detection of breath acetone, a molecule strongly linked with the diabetic condition. Preliminary studies into the suitability of cavity enhanced absorption...

  19. Automatic Recognition of Breathing Route During Sleep Using Snoring Sounds

    Science.gov (United States)

    Mikami, Tsuyoshi; Kojima, Yohichiro

    This letter classifies snoring sounds into three breathing routes (oral, nasal, and oronasal) with discriminant analysis of the power spectra and k-nearest neighbor method. It is necessary to recognize breathing route during snoring, because oral snoring is a typical symptom of sleep apnea but we cannot know our own breathing and snoring condition during sleep. As a result, about 98.8% classification rate is obtained by using leave-one-out test for performance evaluation.

  20. General Anesthesia with Preserved Spontaneous Breathing through an Intubation Tube

    Directory of Open Access Journals (Sweden)

    V. V. Moroz

    2010-01-01

    Full Text Available Objective: to study whether spontaneous patient breathing may be preserved during elective operations under general anesthesia with tracheal intubation. Subjects and methods. One hundred and twelve patients undergoing elective surgeries under general endotracheal anesthesia were randomized into 2 groups: 1 patients who had forced mechanical ventilation in the volume-controlled mode and 2 those who received assisted ventilation as spontaneous breathing with mechanical support. Conclusion. The study shows that spontaneous breathing with mechanical support may be safely used during some surgical interventions in patients with baseline healthy lungs. Key words: Pressure Support, assisted ventilation, spontaneous breathing, general anesthesia, lung function.

  1. Using acoustic sensors to discriminate between nasal and mouth breathing.

    Science.gov (United States)

    Curran, Kevin; Yuan, Peng; Coyle, Damian

    2012-01-01

    The recommendation to change breathing patterns from the mouth to the nose can have a significantly positive impact upon the general well being of the individual. We classify nasal and mouth breathing by using an acoustic sensor and intelligent signal processing techniques. The overall purpose is to investigate the possibility of identifying the differences in patterns between nasal and mouth breathing in order to integrate this information into a decision support system which will form the basis of a patient monitoring and motivational feedback system to recommend the change from mouth to nasal breathing.

  2. A fibre-optic oxygen sensor for monitoring human breathing.

    Science.gov (United States)

    Chen, Rongsheng; Formenti, Federico; Obeid, Andy; Hahn, Clive E W; Farmery, Andrew D

    2013-09-01

    The development and construction of a tapered-tip fibre-optic fluorescence based oxygen sensor is described. The sensor is suitable for fast and real-time monitoring of human breathing. The sensitivity and response time of the oxygen sensor were evaluated in vitro with a gas pressure chamber system, where oxygen partial pressure was rapidly changed between 5 and 15 kPa, and then in vivo in five healthy adult participants who synchronized their breathing to a metronome set at 10, 20, 30, 40, 50, and 60 breaths min(-1). A Datex Ultima medical gas analyser was used to monitor breathing rate as a comparator. The sensor's response time in vitro was less than 150 ms, which allows accurate continuous measurement of inspired and expired oxygen pressure. Measurements of breathing rate by means of our oxygen sensor and of the Datex Ultima were in strong agreement. The results demonstrate that the device can reliably resolve breathing rates up to 60 breaths min(-1), and that it is a suitable cost-effective alternative for monitoring breathing rates and end-tidal oxygen partial pressure in the clinical setting. The rapid response time of the sensor may allow its use for monitoring rapid breathing rates as occur in children and the newborn.

  3. A simple optical fiber interferometer based breathing sensor

    Science.gov (United States)

    Li, Xixi; Liu, Dejun; Kumar, Rahul; Ng, Wai Pang; Fu, Yong-qing; Yuan, Jinhui; Yu, Chongxiu; Wu, Yufeng; Zhou, Guorui; Farrell, Gerald; Semenova, Yuliya; Wu, Qiang

    2017-03-01

    A breathing sensor has been experimentally demonstrated based on a singlemode–multimode–singlemode (SMS) fiber structure which is attached to a thin plastic film in an oxygen mask. By detecting power variations due to the macro bending applied to the SMS section by each inhalation and exhalation process, the breath state can be monitored. The proposed sensor is capable of distinguishing different types of breathing conditions including regular and irregular breath state. The sensor can be used in a strong electric/magnetic field and radioactive testing systems such as magnetic resonance imaging (MRI) systems and computed tomography (CT) examinations where electrical sensors are restricted.

  4. Can resistive breathing injure the lung? Implications for COPD exacerbations

    Directory of Open Access Journals (Sweden)

    Vassilakopoulos T

    2016-09-01

    Full Text Available Theodoros Vassilakopoulos, Dimitrios Toumpanakis Pulmonary and Critical Care Medicine, Medical School, National and Kapodistrian University of Athens, Greece Abstract: In obstructive lung diseases, airway inflammation leads to bronchospasm and thus resistive breathing, especially during exacerbations. This commentary discusses experimental evidence that resistive breathing per se (the mechanical stimulus in the absence of underlying airway inflammation leads to lung injury and inflammation (mechanotransduction. The potential implications of resistive breathing-induced mechanotrasduction in COPD exacerbations are presented along with the available clinical evidence. Keywords: resistive breathing, COPD, mechanotransduction, bronchoconstriction, inflammation

  5. Sports-related lung injury during breath-hold diving

    Directory of Open Access Journals (Sweden)

    Tanja Mijacika

    2016-12-01

    Full Text Available The number of people practising recreational breath-hold diving is constantly growing, thereby increasing the need for knowledge of the acute and chronic effects such a sport could have on the health of participants. Breath-hold diving is potentially dangerous, mainly because of associated extreme environmental factors such as increased hydrostatic pressure, hypoxia, hypercapnia, hypothermia and strenuous exercise. In this article we focus on the effects of breath-hold diving on pulmonary function. Respiratory symptoms have been reported in almost 25% of breath-hold divers after repetitive diving sessions. Acutely, repetitive breath-hold diving may result in increased transpulmonary capillary pressure, leading to noncardiogenic oedema and/or alveolar haemorrhage. Furthermore, during a breath-hold dive, the chest and lungs are compressed by the increasing pressure of water. Rapid changes in lung air volume during descent or ascent can result in a lung injury known as pulmonary barotrauma. Factors that may influence individual susceptibility to breath-hold diving-induced lung injury range from underlying pulmonary or cardiac dysfunction to genetic predisposition. According to the available data, breath-holding does not result in chronic lung injury. However, studies of large populations of breath-hold divers are necessary to firmly exclude long-term lung damage.

  6. Sports-related lung injury during breath-hold diving.

    Science.gov (United States)

    Mijacika, Tanja; Dujic, Zeljko

    2016-12-01

    The number of people practising recreational breath-hold diving is constantly growing, thereby increasing the need for knowledge of the acute and chronic effects such a sport could have on the health of participants. Breath-hold diving is potentially dangerous, mainly because of associated extreme environmental factors such as increased hydrostatic pressure, hypoxia, hypercapnia, hypothermia and strenuous exercise.In this article we focus on the effects of breath-hold diving on pulmonary function. Respiratory symptoms have been reported in almost 25% of breath-hold divers after repetitive diving sessions. Acutely, repetitive breath-hold diving may result in increased transpulmonary capillary pressure, leading to noncardiogenic oedema and/or alveolar haemorrhage. Furthermore, during a breath-hold dive, the chest and lungs are compressed by the increasing pressure of water. Rapid changes in lung air volume during descent or ascent can result in a lung injury known as pulmonary barotrauma. Factors that may influence individual susceptibility to breath-hold diving-induced lung injury range from underlying pulmonary or cardiac dysfunction to genetic predisposition.According to the available data, breath-holding does not result in chronic lung injury. However, studies of large populations of breath-hold divers are necessary to firmly exclude long-term lung damage.

  7. Optimal technique for deep breathing exercises after cardiac surgery.

    Science.gov (United States)

    Westerdahl, E

    2015-06-01

    Cardiac surgery patients often develop a restrictive pulmonary impairment and gas exchange abnormalities in the early postoperative period. Chest physiotherapy is routinely prescribed in order to reduce or prevent these complications. Besides early mobilization, positioning and shoulder girdle exercises, various breathing exercises have been implemented as a major component of postoperative care. A variety of deep breathing maneuvres are recommended to the spontaneously breathing patient to reduce atelectasis and to improve lung function in the early postoperative period. Different breathing exercises are recommended in different parts of the world, and there is no consensus about the most effective breathing technique after cardiac surgery. Arbitrary instructions are given, and recommendations on performance and duration vary between hospitals. Deep breathing exercises are a major part of this therapy, but scientific evidence for the efficacy has been lacking until recently, and there is a lack of trials describing how postoperative breathing exercises actually should be performed. The purpose of this review is to provide a brief overview of postoperative breathing exercises for patients undergoing cardiac surgery via sternotomy, and to discuss and suggest an optimal technique for the performance of deep breathing exercises.

  8. Ocean urea fertilization for carbon credits poses high ecological risks.

    Science.gov (United States)

    Glibert, Patricia M; Azanza, Rhodora; Burford, Michele; Furuya, Ken; Abal, Eva; Al-Azri, Adnan; Al-Yamani, Faiza; Andersen, Per; Anderson, Donald M; Beardall, John; Berg, G Mine; Brand, Larry; Bronk, Deborah; Brookes, Justin; Burkholder, Joann M; Cembella, Allan; Cochlan, William P; Collier, Jackie L; Collos, Yves; Diaz, Robert; Doblin, Martina; Drennen, Thomas; Dyhrman, Sonya; Fukuyo, Yasuwo; Furnas, Miles; Galloway, James; Granéli, Edna; Ha, Dao Viet; Hallegraeff, Gustaaf; Harrison, John; Harrison, Paul J; Heil, Cynthia A; Heimann, Kirsten; Howarth, Robert; Jauzein, Cécile; Kana, Austin A; Kana, Todd M; Kim, Hakgyoon; Kudela, Raphael; Legrand, Catherine; Mallin, Michael; Mulholland, Margaret; Murray, Shauna; O'Neil, Judith; Pitcher, Grant; Qi, Yuzao; Rabalais, Nancy; Raine, Robin; Seitzinger, Sybil; Salomon, Paulo S; Solomon, Caroline; Stoecker, Diane K; Usup, Gires; Wilson, Joanne; Yin, Kedong; Zhou, Mingjiang; Zhu, Mingyuan

    2008-06-01

    The proposed plan for enrichment of the Sulu Sea, Philippines, a region of rich marine biodiversity, with thousands of tonnes of urea in order to stimulate algal blooms and sequester carbon is flawed for multiple reasons. Urea is preferentially used as a nitrogen source by some cyanobacteria and dinoflagellates, many of which are neutrally or positively buoyant. Biological pumps to the deep sea are classically leaky, and the inefficient burial of new biomass makes the estimation of a net loss of carbon from the atmosphere questionable at best. The potential for growth of toxic dinoflagellates is also high, as many grow well on urea and some even increase their toxicity when grown on urea. Many toxic dinoflagellates form cysts which can settle to the sediment and germinate in subsequent years, forming new blooms even without further fertilization. If large-scale blooms do occur, it is likely that they will contribute to hypoxia in the bottom waters upon decomposition. Lastly, urea production requires fossil fuel usage, further limiting the potential for net carbon sequestration. The environmental and economic impacts are potentially great and need to be rigorously assessed.

  9. Urea cycle disorders: brain MRI and neurological outcome

    Energy Technology Data Exchange (ETDEWEB)

    Bireley, William R. [University of Colorado, Department of Radiology, Aurora, CO (United States); Van Hove, Johan L.K. [University of Colorado, Department of Genetics and Inherited Metabolic Diseases, Aurora, CO (United States); Gallagher, Renata C. [Children' s Hospital Colorado, Department of Genetics and Inherited Metabolic Diseases, Aurora, CO (United States); Fenton, Laura Z. [Children' s Hospital Colorado, Department of Pediatric Radiology, Aurora, CO (United States)

    2012-04-15

    Urea cycle disorders encompass several enzyme deficiencies that can result in cerebral damage, with a wide clinical spectrum from asymptomatic to severe. The goal of this study was to correlate brain MRI abnormalities in urea cycle disorders with clinical neurological sequelae to evaluate whether MRI abnormalities can assist in guiding difficult treatment decisions. We performed a retrospective chart review of patients with urea cycle disorders and symptomatic hyperammonemia. Brain MRI images were reviewed for abnormalities that correlated with severity of clinical neurological sequelae. Our case series comprises six urea cycle disorder patients, five with ornithine transcarbamylase deficiency and one with citrullinemia type 1. The observed trend in distribution of brain MRI abnormalities as the severity of neurological sequelae increased was the peri-insular region first, extending into the frontal, parietal, temporal and, finally, the occipital lobes. There was thalamic restricted diffusion in three children with prolonged hyperammonemia. Prior to death, this site is typically reported to be spared in urea cycle disorders. The pattern and extent of brain MRI abnormalities correlate with clinical neurological outcome in our case series. This suggests that brain MRI abnormalities may assist in determining prognosis and helping clinicians with subsequent treatment decisions. (orig.)

  10. Ocean Urea Fertilization for Carbon Credits Poses High Ecological Risks

    Science.gov (United States)

    Glibert, Patricia M.; Azanza, Rhodora; Burford, Michele; Furuya, Ken; Abal, Eva; Al-Azri, Adnan; Al-Yamani, Faiza; Andersen, Per; Beardall, John; Berg, G. Mine; Brand, Larry; Bronk, Deborah; Brookes, Justin; Burkholder, JoAnn M.; Cembella, Allan; Cochlan, William P.; Collier, Jackie; Collos, Yves; Diaz, Robert; Doblin, Martina; Drennen, Thomas; Dyhrman, Sonya; Fukuyo, Yasuwo; Furnas, Miles; Galloway, James; Granéli, Edna; Ha, Dao Viet; Hallegraeff, Gustaaf; Harrison, John; Harrison, Paul J.; Heil, Cynthia A.; Heimann, Kirsten; Howarth, Robert; Jauzein, Cécile; Kana, Austin A.; Kana, Todd M.; Kim, Hakgyoon; Kudela, Raphael; Legrand, Catherine; Mallin, Michael; Mulholland, Margaret; Murray, Shauna; O’Neil, Judith; Pitcher, Grant; Qi, Yuzao; Rabalais, Nancy; Raine, Robin; Seitzinger, Sybil; Solomon, Caroline; Stoecker, Diane K.; Usup, Gires; Wilson, Joanne; Yin, Kedong; Zhou, Mingjiang; Zhu, Mingyuan

    2017-01-01

    The proposed plan for enrichment of the Sulu Sea, Philippines, a region of rich marine biodiversity, with thousands of tonnes of urea in order to stimulate algal blooms and sequester carbon is flawed for multiple reasons. Urea is preferentially used as a nitrogen source by some cyanobacteria and dinoflagellates, many of which are neutrally or positively buoyant. Biological pumps to the deep sea are classically leaky, and the inefficient burial of new biomass makes the estimation of a net loss of carbon from the atmosphere questionable at best. The potential for growth of toxic dinoflagellates is also high, as many grow well on urea and some even increase their toxicity when grown on urea. Many toxic dinoflagellates form cysts which can settle to the sediment and germinate in subsequent years, forming new blooms even without further fertilization. If large-scale blooms do occur, it is likely that they will contribute to hypoxia in the bottom waters upon decomposition. Lastly, urea production requires fossil fuel usage, further limiting the potential for net carbon sequestration. The environmental and economic impacts are potentially great and need to be rigorously assessed. PMID:18439628

  11. Hydrotropic Solubilization by Urea Derivatives: A Molecular Dynamics Simulation Study

    Directory of Open Access Journals (Sweden)

    Yong Cui

    2013-01-01

    Full Text Available Hydrotropy is a phenomenon where the presence of a large quantity of one solute enhances the solubility of another solute. The mechanism of this phenomenon remains a topic of debate. This study employed molecular dynamics simulation to investigate the hydrotropic mechanism of a series of urea derivatives, that is, urea (UR, methylurea (MU, ethylurea (EU, and butylurea (BU. A poorly water-soluble compound, nifedipine (NF, was used as the model solute that was solubilized. Structural, dynamic, and energetic changes upon equilibration were analyzed to supply insights to the solubilization mechanism. The study demonstrated that NF and urea derivatives underwent significant nonstoichiometric molecular aggregation in the aqueous solution, a result consistent with the self-aggregation of urea derivatives under the same conditions. The analysis of hydrogen bonding and energy changes revealed that the aggregation was driven by the partial restoration of normal water structure. The energetic data also suggested that the promoted solubilization of NF is favored in the presence of urea derivatives. While the solutes aggregated to a varying degree, the systems were still in single-phase liquid state as attested by their active dynamics.

  12. Porous Cross-Linked Polyimide-Urea Networks

    Science.gov (United States)

    Meador, Mary Ann B. (Inventor); Nguyen, Baochau N. (Inventor)

    2015-01-01

    Porous cross-linked polyimide-urea networks are provided. The networks comprise a subunit comprising two anhydride end-capped polyamic acid oligomers in direct connection via a urea linkage. The oligomers (a) each comprise a repeating unit of a dianhydride and a diamine and a terminal anhydride group and (b) are formulated with 2 to 15 of the repeating units. The subunit was formed by reaction of the diamine and a diisocyanate to form a diamine-urea linkage-diamine group, followed by reaction of the diamine-urea linkage-diamine group with the dianhydride and the diamine to form the subunit. The subunit has been cross-linked via a cross-linking agent, comprising three or more amine groups, at a balanced stoichiometry of the amine groups to the terminal anhydride groups. The subunit has been chemically imidized to yield the porous cross-linked polyimide-urea network. Also provided are wet gels, aerogels, and thin films comprising the networks, and methods of making the networks.

  13. The Formation and characteristics of Acrylonitrile/Urea Inclusion Compound

    CERN Document Server

    Zou, Jun-Ting; Pang, Wen-Min; Shi, Lei; Lu, Fei

    2012-01-01

    The formation process and composition of the acrylonitrile/urea inclusion compounds (AN/UIC) with different aging times and AN/urea molar feed ratios are studied by differential scanning calorimetry (DSC) and X-ray diffraction (XRD). It is suggested that DSC could be one of the helpful methods to determine the guest/host ratio and the heat of decomposition. Meanwhile, the guest/host ratio and heat of deformation are obtained, which are 1.17 and 5361.53 J/mol, respectively. It is found that the formation of AN/UIC depends on the aging time. The formation process ends after enough aging time and the composition of AN/UIC becomes stable. It is suggested AN molecules included in urea canal lattice may be packed flat against each other. XRD results reveal that once AN molecules enter urea lattice, AN/UIC are formed, which possess the final structure. When AN molecules are sufficient, the content of AN/UIC increased as aging time prolonging until urea tunnels are saturated by AN.

  14. Electronic response to nuclear breathing mode

    Energy Technology Data Exchange (ETDEWEB)

    Ludwig, Hendrik; Ruffini, Remo [ICRANet, P.zza della Repubblica 10, I-65122 Pescara, Italy Dipartimento di Fisica and ICRA, Sapienza Università di Roma P.le Aldo Moro 5, I-00185 Rome (Italy); ICRANet, University of Nice-Sophia Antipolis, 28 Av. de Valrose, 06103 Nice Cedex 2 (France); Xue, She-Sheng [ICRANet, P.zza della Repubblica 10, I-65122 Pescara, Italy Dipartimento di Fisica and ICRA, Sapienza Università di Roma P.le Aldo Moro 5, I-00185 Rome (Italy)

    2015-12-17

    Based on our previous work on stationary oscillation modes of electrons around giant nuclei, we show how to treat a general driving force on the electron gas, such as the one generated by the breathing mode of the nucleus, by means of the spectral method. As an example we demonstrate this method for a system with Z = 10{sup 4} in β-equilibrium with the electrons compressed up to the nuclear radius. In this case the stationary modes can be obtained analytically, which allows for a very speedy numerical calculation of the final result.

  15. Exhaled breath condensate pH assays.

    Science.gov (United States)

    Davis, Michael D; Hunt, John

    2012-08-01

    Airway pH is central to the physiologic function and cellular biology of the airway. The causes of airway acidification include (1) hypopharyngeal gastric acid reflux with or without aspiration through the vocal cords, (2) inhalation of acid fog or gas (such as chlorine), and (3) intrinsic airway acidification caused by altered airway pH homeostasis in infectious and inflammatory disease processes. The recognition that relevant airway pH deviations occur in lung diseases is opening doors to new simple and inexpensive therapies. This recognition has resulted partly from the ability to use exhaled breath condensate as a window on airway acid-base balance.

  16. Exhaled Breath Condensate for Proteomic Biomarker Discovery

    Directory of Open Access Journals (Sweden)

    Sean W. Harshman

    2014-07-01

    Full Text Available Exhaled breath condensate (EBC has been established as a potential source of respiratory biomarkers. Compared to the numerous small molecules identified, the protein content of EBC has remained relatively unstudied due to the methodological and technical difficulties surrounding EBC analysis. In this review, we discuss the proteins identified in EBC, by mass spectrometry, focusing on the significance of those proteins identified. We will also review the limitations surrounding mass spectral EBC protein analysis emphasizing recommendations to enhance EBC protein identifications by mass spectrometry. Finally, we will provide insight into the future directions of the EBC proteomics field.

  17. System of Optoelectronic Sensors for Breath Analysis

    Directory of Open Access Journals (Sweden)

    Mikołajczyk Janusz

    2016-09-01

    Full Text Available The paper describes an integrated laser absorption system as a potential tool for breath analysis for clinical diagnostics, online therapy monitoring and metabolic disorder control. The sensors operate basing on cavity enhanced spectroscopy and multi-pass spectroscopy supported by wavelength modulation spectroscopy. The aspects concerning selection of operational spectral range and minimization of interference are also discussed. Tests results of the constructed devices collected with reference samples of biomarkers are also presented. The obtained data provide an opportunity to analyse applicability of optoelectronic sensors in medical screening.

  18. Extensive Epidermoid Cyst and Breathing Difficulty

    Directory of Open Access Journals (Sweden)

    Ciro Dantas Soares

    2015-01-01

    Full Text Available Epidermoid cysts are common cystic lesions in the skin, ovaries, and testicles, but their occurrence in the oral cavity is uncommon. They consist of cysts delimited by a fibrous capsule without cutaneous annexes and are lined by stratified squamous epithelium. The differential diagnosis includes ranula, dermoid cysts, and lingual thyroid. Despite their benign presentation, these cysts can cause functional limitations, requiring special clinical attention for extensive lesions located in regions that preserve vital structures. This paper aims to report a case of epidermoid cyst in patient with swallowing and breathing difficulty, highlighting the clinical and surgical planning.

  19. A young male with shortness of breath

    Directory of Open Access Journals (Sweden)

    Khan Fahmi

    2008-01-01

    Full Text Available We report a case of primary mediastinal seminoma, which presented initially with shortness of breath and a swelling in upper part of anterior chest wall. The diagnosis of primary mediastinal seminoma was established on the basis of histologic findings and was confirmed by immunohistochemical analysis. Abdominal, pelvis and cerebral CT scan, testicular ultrasound and TC-99 MDP bone scintigraphy were negative. Chemotherapy was initiated with B.E.P. protocol (Bleomycin, Etoposide, Cisplatinum; the patient received four cycles of chemotherapy. After 8 months, the patient was seen in the clinic; he was well.

  20. Extensive Epidermoid Cyst and Breathing Difficulty

    Science.gov (United States)

    Soares, Ciro Dantas; Gurgel, Alberto Costa; de Souza Júnior, Francisco de Assis; de Oliveira, Samila Neres; de Carvalho, Maria Goretti Freire; Oliveira, Hanieri Gustavo

    2015-01-01

    Epidermoid cysts are common cystic lesions in the skin, ovaries, and testicles, but their occurrence in the oral cavity is uncommon. They consist of cysts delimited by a fibrous capsule without cutaneous annexes and are lined by stratified squamous epithelium. The differential diagnosis includes ranula, dermoid cysts, and lingual thyroid. Despite their benign presentation, these cysts can cause functional limitations, requiring special clinical attention for extensive lesions located in regions that preserve vital structures. This paper aims to report a case of epidermoid cyst in patient with swallowing and breathing difficulty, highlighting the clinical and surgical planning. PMID:26180645

  1. Appropriate sample bags and syringes for preserving breath samples in breath odor research : a technical note

    NARCIS (Netherlands)

    Winkel, E. G.; Tangerman, A.

    2008-01-01

    It is now generally accepted that the volatile sulfur compounds (VSCs) hydrogen sulfide, methyl mercaptan and dimethyl sulfide are the main contributors to halitosis when of oropharyngeal origin. The VSCs hydrogen sulfide and methyl mercaptan are the major causes of bad breath in oral malodour where

  2. Modeling and measurement of boiling point elevation during water vaporization from aqueous urea for SCR applications

    Energy Technology Data Exchange (ETDEWEB)

    Dan, Ho Jin; Lee, Joon Sik [Seoul National University, Seoul (Korea, Republic of)

    2016-03-15

    Understanding of water vaporization is the first step to anticipate the conversion process of urea into ammonia in the exhaust stream. As aqueous urea is a mixture and the urea in the mixture acts as a non-volatile solute, its colligative properties should be considered during water vaporization. The elevation of boiling point for urea water solution is measured with respect to urea mole fraction. With the boiling-point elevation relation, a model for water vaporization is proposed underlining the correction of the heat of vaporization of water in the urea water mixture due to the enthalpy of urea dissolution in water. The model is verified by the experiments of water vaporization as well. Finally, the water vaporization model is applied to the water vaporization of aqueous urea droplets. It is shown that urea decomposition can begin before water evaporation finishes due to the boiling-point elevation.

  3. Improving ammonium and nitrate release from urea using clinoptilolite zeolite and compost produced from agricultural wastes.

    Science.gov (United States)

    Omar, Latifah; Ahmed, Osumanu Haruna; Ab Majid, Nik Muhamad

    2015-01-01

    Improper use of urea may cause environmental pollution through NH3 volatilization and NO3 (-) leaching from urea. Clinoptilolite zeolite and compost could be used to control N loss from urea by controlling NH4 (+) and NO3 (-) release from urea. Soil incubation and leaching experiments were conducted to determine the effects of clinoptilolite zeolite and compost on controlling NH4 (+) and NO3 (-) losses from urea. Bekenu Series soil (Typic Paleudults) was incubated for 30, 60, and 90 days. A soil leaching experiment was conducted for 30 days. Urea amended with clinoptilolite zeolite and compost significantly reduced NH4 (+) and NO3 (-) release from urea (soil incubation study) compared with urea alone, thus reducing leaching of these ions. Ammonium and NO3 (-) leaching losses during the 30 days of the leaching experiment were highest in urea alone compared with urea with clinoptilolite zeolite and compost treatments. At 30 days of the leaching experiment, NH4 (+) retention in soil with urea amended with clinoptilolite zeolite and compost was better than that with urea alone. These observations were because of the high pH, CEC, and other chemical properties of clinoptilolite zeolite and compost. Urea can be amended with clinoptilolite zeolite and compost to improve NH4 (+) and NO3 (-) release from urea.

  4. Improving Ammonium and Nitrate Release from Urea Using Clinoptilolite Zeolite and Compost Produced from Agricultural Wastes

    Directory of Open Access Journals (Sweden)

    Latifah Omar

    2015-01-01

    Full Text Available Improper use of urea may cause environmental pollution through NH3 volatilization and NO3- leaching from urea. Clinoptilolite zeolite and compost could be used to control N loss from urea by controlling NH4+ and NO3- release from urea. Soil incubation and leaching experiments were conducted to determine the effects of clinoptilolite zeolite and compost on controlling NH4+ and NO3- losses from urea. Bekenu Series soil (Typic Paleudults was incubated for 30, 60, and 90 days. A soil leaching experiment was conducted for 30 days. Urea amended with clinoptilolite zeolite and compost significantly reduced NH4+ and NO3- release from urea (soil incubation study compared with urea alone, thus reducing leaching of these ions. Ammonium and NO3- leaching losses during the 30 days of the leaching experiment were highest in urea alone compared with urea with clinoptilolite zeolite and compost treatments. At 30 days of the leaching experiment, NH4+ retention in soil with urea amended with clinoptilolite zeolite and compost was better than that with urea alone. These observations were because of the high pH, CEC, and other chemical properties of clinoptilolite zeolite and compost. Urea can be amended with clinoptilolite zeolite and compost to improve NH4+ and NO3- release from urea.

  5. STUDY ON NOVEL SORBENT FOR REMOVAL OF UREA COMPLEX SORPTION OF UREA BY MEANS OF ALGINATE—Cu(Ⅱ) COMPLEX

    Institute of Scientific and Technical Information of China (English)

    ZHAOXiaobin; HEBinglin

    1992-01-01

    Alginate-Cu(Ⅱ)complex beads or membranes were prepared for removal of urea.The mechanism of sorption of urea was identified by UV-Visible spectra,FT-IR spectra and Far-Infrared spectra.The factors affecting the urea sorption capacity were discussed in detail.Results showed that the Alginate-Cu(Ⅱ)complex sorbent can sorb about 60 my urea per gram of sorbent at 37℃ and the concentration of urea was 130mg/100ml in Na2HPO4 and NaH2PO4 buffer solution(pH=7.0).

  6. Study of the behaviour of organic carbon in the soil, and carbon 14 study of podzols; Contribution a l'etude du comportement du carbone organique dans le sol et etude des podzols a l'aide du carbone 14

    Energy Technology Data Exchange (ETDEWEB)

    Nakhla Shawki, M. [Commissariat a l' Energie Atomique, Saclay (France). Centre d' Etudes Nucleaires

    1969-07-01

    Using the penetration into soil of carbon 14 of thermo-nuclear origin, the behaviour and renewal rate were studied on different organic fractions of the soil. It was established that 18% of the total organic matter is renewed in about 400 years. In addition the formation of podzol-type fossil soils in France was dated from the first millenary B.C., i.e. the end of the sub-boreal period and the beginning of the atlantic period. (author) [French] En utilisant la penetration dans le sol du carbone 14 d'origine thermonucleaire, on a etudie le comportement et la vitesse de renouvellement des differentes fractions de la matiere organique du sol. On a pu preciser que 18% de la matiere organique globale se renouvelait en 400 ans environ. Par ailleurs, la formation en France des sols fossiles du type podzol a ete datee du premier millenaire avant J.C. c'est a dire a la fin de la periode subboreale et au debut de la periode atlantique. (auteur)

  7. Substituted urea derivatives: a potent class of antidepressant agents.

    Science.gov (United States)

    Perveen, Shahnaz; Mustafa, Sana; Khan, Muhammad A; Dar, Ahsana; Khan, Khalid M; Voelter, Wolfgang

    2012-05-01

    A series of fourteen (14) N-nitrophenyl-N'-(alkyl/aryl)urea and symmetrical 1,3-disubstituted urea derivatives were synthesized and evaluated for their antidepressant activity in mice. Among them, N-(4-nitrophenyl)-N'-(1'-phenylethyl)urea (1), demonstrated profound antidepressant property as reflected by significant reduction in the immobility time (89.83%), whereas compounds 2-6 showed activity values between 36 to 59% which were also larger than the standard phenelzine. Compounds 7-9 were less effective in reducing the immobility period of mice 26.20 to 31.01%). This variable magnitude of antidepressant activity appears to be related to the position of the nitro group to the parent molecules 1, 2, and 8. Compound 1 with the nitro group at para position showed to be the most effective antidepressant. However, the activity declined, if the nitro is attached to ortho and meta positions.

  8. Biosensor Urea Berbasis Biopolimer Khitin Sebagai Matriks Immobilisasi

    Directory of Open Access Journals (Sweden)

    Nazruddin Nazaruddin

    2007-06-01

    Full Text Available Penelitian tentang biosensor urea menggunakan biopolimer khitin sebagai matriks immobilisasi telah dilakukan. Penelitian ini dilakukan untuk mengetahui kinerja biosensor yang dihasilkan yang meliputi sensitivitas, trayek pengukuran, limit deteksi, waktu respon, koefisien selektifitas, dan waktu hidup. Penelitian meliputi beberapa tahap yaitu pembuatan membran polimer khitin dan immobilisasi enzim urease, pelekatan membran khitin pada elektroda pH, dan pengukuran parameter kinerja elektroda. Hasil pengukuran menunjukkan sensitivitas biosensor urea berbasis membran khitin adalah 19,11 mV/dekade, trayek pengukuran 10-4 – 10-8 M, limit deteksi 10-8 M, waktu respon 3,10–6,02 menit, dengan urutan kekuatan ion penggangu: NH4Cl > NaCl > CH3COONa > campuran garam > KCl > CaCl2 > asam askorbat. Kata kunci: biosensor, immobilisasi, khitin, urea

  9. Android integrated urea biosensor for public health awareness

    Directory of Open Access Journals (Sweden)

    Pranali P. Naik

    2015-03-01

    Full Text Available Integration of a biosensor with a wireless network on the Android 4.2.1 (Jelly Bean platform has been demonstrated. The present study reports an android integrated user friendly Flow injection analysis-Enzyme thermistor (FIA-ET urea biosensor system. This android-integrated biosensor system will facilitate enhanced consumer health and awareness alongside abridging the gap between the food testing laboratory and the concerned higher authorities. Data received from a flow injection mode urea biosensor has been exploited as an integration point among the analyst, the food consumer and the responsible higher authorities. Using the urea biosensor as an example, an alarm system has also been demonstrated both graphically and through text message on a mobile handset. The presented sensor integrated android system will also facilitate decision making support system in various fields of food quality monitoring and clinical analysis.

  10. Waste-to-Chemicals for a Circular Economy: The Case of Urea Production (Waste-to-Urea).

    Science.gov (United States)

    Antonetti, Elena; Iaquaniello, Gaetano; Salladini, Annarita; Spadaccini, Luca; Perathoner, Siglinda; Centi, Gabriele

    2017-03-09

    The economics and environmental impact of a new technology for the production of urea from municipal solid waste, particularly the residue-derived fuel (RdF) fraction, is analyzed. Estimates indicate a cost of production of approximately €135 per ton of urea (internal rate of return more than 10 %) and savings of approximately 0.113 tons of CH4 and approximately 0.78 tons of CO2 per ton of urea produced. Thus, the results show that this waste-to-urea (WtU) technology is both economically valuable and environmentally advantageous (in terms of saving resources and limiting carbon footprint) for the production of chemicals from municipal solid waste in comparison with both the production of urea with conventional technology (starting from natural gas) and the use of RdF to produce electrical energy (waste-to-energy). A further benefit is the lower environmental impact of the solid residue produced from RdF conversion. The further benefit of this technology is the possibility to realize distributed fertilizer production.

  11. A fully integrated standalone portable cavity ringdown breath acetone analyzer

    Science.gov (United States)

    Sun, Meixiu; Jiang, Chenyu; Gong, Zhiyong; Zhao, Xiaomeng; Chen, Zhuying; Wang, Zhennan; Kang, Meiling; Li, Yingxin; Wang, Chuji

    2015-09-01

    Breath analysis is a promising new technique for nonintrusive disease diagnosis and metabolic status monitoring. One challenging issue in using a breath biomarker for potential particular disease screening is to find a quantitative relationship between the concentration of the breath biomarker and clinical diagnostic parameters of the specific disease. In order to address this issue, we need a new instrument that is capable of conducting real-time, online breath analysis with high data throughput, so that a large scale of clinical test (more subjects) can be achieved in a short period of time. In this work, we report a fully integrated, standalone, portable analyzer based on the cavity ringdown spectroscopy technique for near-real time, online breath acetone measurements. The performance of the portable analyzer in measurements of breath acetone was interrogated and validated by using the certificated gas chromatography-mass spectrometry. The results show that this new analyzer is useful for reliable online (online introduction of a breath sample without pre-treatment) breath acetone analysis with high sensitivity (57 ppb) and high data throughput (one data per second). Subsequently, the validated breath analyzer was employed for acetone measurements in 119 human subjects under various situations. The instrument design, packaging, specifications, and future improvements were also described. From an optical ringdown cavity operated by the lab-set electronics reported previously to this fully integrated standalone new instrument, we have enabled a new scientific tool suited for large scales of breath acetone analysis and created an instrument platform that can even be adopted for study of other breath biomarkers by using different lasers and ringdown mirrors covering corresponding spectral fingerprints.

  12. Patient-specific simulation of tidal breathing

    Science.gov (United States)

    Walters, M.; Wells, A. K.; Jones, I. P.; Hamill, I. S.; Veeckmans, B.; Vos, W.; Lefevre, C.; Fetitia, C.

    2016-03-01

    Patient-specific simulation of air flows in lungs is now straightforward using segmented airways trees from CT scans as the basis for Computational Fluid Dynamics (CFD) simulations. These models generally use static geometries, which do not account for the motion of the lungs and its influence on important clinical indicators, such as airway resistance. This paper is concerned with the simulation of tidal breathing, including the dynamic motion of the lungs, and the required analysis workflow. Geometries are based on CT scans obtained at the extremes of the breathing cycle, Total Lung Capacity (TLC) and Functional Residual Capacity (FRC). It describes how topologically consistent geometries are obtained at TLC and FRC, using a `skeleton' of the network of airway branches. From this a 3D computational mesh which morphs between TLC and FRC is generated. CFD results for a number of patient-specific cases, healthy and asthmatic, are presented. Finally their potential use in evaluation of the progress of the disease is discussed, focusing on an important clinical indicator, the airway resistance.

  13. Exhaled Breath Condensate: Technical and Diagnostic Aspects

    Directory of Open Access Journals (Sweden)

    Efstathia M. Konstantinidi

    2015-01-01

    Full Text Available Purpose. The aim of this study was to evaluate the 30-year progress of research on exhaled breath condensate in a disease-based approach. Methods. We searched PubMed/Medline, ScienceDirect, and Google Scholar using the following keywords: exhaled breath condensate (EBC, biomarkers, pH, asthma, gastroesophageal reflux (GERD, smoking, COPD, lung cancer, NSCLC, mechanical ventilation, cystic fibrosis, pulmonary arterial hypertension (PAH, idiopathic pulmonary fibrosis, interstitial lung diseases, obstructive sleep apnea (OSA, and drugs. Results. We found 12600 related articles in total in Google Scholar, 1807 in ScienceDirect, and 1081 in PubMed/Medline, published from 1980 to October 2014. 228 original investigation and review articles were eligible. Conclusions. There is rapidly increasing number of innovative articles, covering all the areas of modern respiratory medicine and expanding EBC potential clinical applications to other fields of internal medicine. However, the majority of published papers represent the results of small-scale studies and thus current knowledge must be further evaluated in large cohorts. In regard to the potential clinical use of EBC-analysis, several limitations must be pointed out, including poor reproducibility of biomarkers and absence of large surveys towards determination of reference-normal values. In conclusion, contemporary EBC-analysis is an intriguing achievement, but still in early stage when it comes to its application in clinical practice.

  14. Screening Sleep Disordered Breathing in Stroke Unit

    Directory of Open Access Journals (Sweden)

    Kirsi Väyrynen

    2014-01-01

    Full Text Available In acute stroke, OSA has been found to impair rehabilitation and increase mortality but the effect of central apnea is more unclear. The aim of the present study was to evaluate the feasibility of using limited ambulatory recording system (sleep mattress to evaluate nocturnal breathing and EOG-electrodes for sleep staging in sleep disordered breathing (SDB diagnostics in mild acute cerebral ischemia patients and to discover the prevalence of various SDB-patterns among these patients. 42 patients with mild ischemic stroke or transient ischemic attack were studied. OSA was found in 22 patients (52.4%. Central apnea was found in two patients (4.8% and sustained partial obstruction in only one patient (2.4%. Sleep staging with EOG-electrodes only yielded a similar outcome as scoring with standard rules. OSA was found to be common even after mild stroke. Its early diagnosis and treatment would be favourable in order to improve recovery and reduce mortality. Our results suggest that OSA can be assessed by a limited recording setting with EOG-electrodes, sleep mattress, and pulse oximetry.

  15. Epiglottic movements during breathing in humans

    Science.gov (United States)

    Amis, T C; O'Neill, N; Di Somma, E; Wheatley, J R

    1998-01-01

    Using X-ray fluoroscopy we measured antero-posterior (A–P) and cranio-caudal (C–C) displacements of the epiglottic tip (ET), corniculate cartilage and hyoid bone in seven seated, normal human subjects (age 34 ± 3 years; mean ±s.e.m.; 4 males, 3 females) breathing via a nasal mask or mouthpiece with (RL) and without (UB) a fixed resistive load.During UB, via either mouth or nose, there were no significant A-P ET movements. During RL via the nose the ET at peak expiratory flow was 2.6 ± 1.3 mm cranial to its position at peak inspiratory flow (P <0.05, ANOVA). C–C movements of the ET correlated strongly with C-C movements of the corniculate cartilage and hyoid bone.The ET, corniculate cartilage and hyoid bone (at zero airflow) were situated more caudally during oral UB than for any other condition.When present, epiglottic movements during breathing do not appear to be independent of those of the larynx and hyoid. Furthermore, epiglottic position may be related to the level of upper airway resistance. PMID:9729637

  16. Biodegraded and Polyurethane Drape-formed Urea Fertilizer

    Institute of Scientific and Technical Information of China (English)

    WANG Yong; LI Jian; CHEN Xiaoyao

    2005-01-01

    Natural water absorbent konjac flour participates in synthesizing biodegraded and polyurethane foamed drape, which is used to release urea slowly.The experimental results indicate that the slowly-releasing velocity of urea nitrogen and the degrading velocity of the drape can be controlled by regulating the thicknesses of drapes, the amount of konjac flour and the water content. In addition, the biodegradability of the drape was investigated by burying the specimens in earth afterwards,and results show this drape can be degraded naturally.

  17. Urea- and Thiourea-Catalyzed Aminolysis of Carbonates.

    Science.gov (United States)

    Blain, Marine; Yau, Honman; Jean-Gérard, Ludivine; Auvergne, Rémi; Benazet, Dominique; Schreiner, Peter R; Caillol, Sylvain; Andrioletti, Bruno

    2016-08-23

    The aminolysis of (poly)carbonates by (poly)amines provides access to non-isocyanate polyurethanes (NIPUs) that are toxic-reagent-free analogues of polyurethanes (PUs). Owing to their low reactivity, the ring opening of cyclic carbonates requires the use of a catalyst. Herein, we report that the more available and cheaper ureas could advantageously be used for catalyzing the formation of NIPUs at the expense of the thiourea analogues. In addition, we demonstrate a medium-range pKa of the (thio)urea and an unqeual substitution pattern is critical for controlling the efficiency of the carbonate opening.

  18. Definition, discrimination, diagnosis and treatment of central breathing disturbances during sleep

    NARCIS (Netherlands)

    Randerath, Winfried; Verbraecken, Johan; Andreas, Stefan; Arzt, Michael; Bloch, Konrad E; Brack, Thomas; Buyse, Bertien; De Backer, Wilfried; Eckert, Danny Joel; Grote, Ludger; Hagmeyer, Lars; Hedner, Jan; Jennum, Poul; La Rovere, Maria Teresa; Miltz, Carla; McNicholas, Walter T; Montserrat, Josep; Naughton, Matthew; Pepin, Jean-Louis; Pevernagie, Dirk; Sanner, Bernd; Testelmans, Dries; Tonia, Thomy; Vrijsen, Bart; Wijkstra, Peter; Levy, Patrick

    2016-01-01

    The complexity of central breathing disturbances during sleep has become increasingly obvious. They present as central sleep apnoeas (CSAs) and hypopnoeas, periodic breathing with apnoeas, or irregular breathing in patients with cardiovascular, other internal or neurological disorders, and can emerg

  19. Definition, discrimination, diagnosis and treatment of central breathing disturbances during sleep

    DEFF Research Database (Denmark)

    Randerath, Winfried; Verbraecken, Johan; Andreas, Stefan;

    2017-01-01

    The complexity of central breathing disturbances during sleep has become increasingly obvious. They present as central sleep apnoeas (CSAs) and hypopnoeas, periodic breathing with apnoeas, or irregular breathing in patients with cardiovascular, other internal or neurological disorders, and can em...

  20. pH-Dependent urea-induced unfolding of stem bromelain: unusual stability against urea at neutral pH.

    Science.gov (United States)

    Ahmad, B; Rathar, G M; Varshney, A; Khan, R H

    2009-12-01

    Equilibrium unfolding of stem bromelain (SB) with urea as a denaturant has been monitored as a function of pH using circular dichroism and fluorescence emission spectroscopy. Urea-induced denaturation studies at pH 4.5 showed that SB unfolds through a two-state mechanism and yields DeltaG (free energy difference between the fully folded and unfolded forms) of approximately 5.0 kcal/mol and C(m) (midpoint of the unfolding transition) of approximately 6.5 M at 25 degrees C. Very high concentration of urea (9.5 M) provides unusual stability to the protein with no more structural loss and transition to a completely unfolded state.

  1. Hydrothermally treated oil palm empty fruit bunch cellulose with urea and its dissolution in NaOH-Urea solvent system

    Science.gov (United States)

    Baharin, Khairunnisa Waznah; Zakaria, Sarani; Gan, Sinyee; Jaafar, Sharifah Nabihah Syed; Chia, Chin Hua

    2016-11-01

    Cellulose from Oil Palm Empty fruit bunch (OPEFB) fiber was hydrothermally treated by using autoclave which is immersed in an oil bath at 160 °C for 6 h. OPEFB cellulose was mixed with aqueous urea and stirred for 30 min to obtain a homogenous mixture before transferred into the autoclave. The effect of different cellulose to urea mass ratio (1:4, 1:6 and 1:8) on the molecular weight, degree of polymerization and solubility of the treated cellulose dissolved in NaOH and urea solvent system was studied. The result shows that the solubility of cellulose from OPEFB fiber increased while the molecular weight of cellulose decreased due to the pretreatment done on the OPEFB fiber.

  2. [Prevalence of mouth breathing in children from an elementary school].

    Science.gov (United States)

    Felcar, Josiane Marques; Bueno, Izabele Rafael; Massan, Ana Carolina Silva; Torezan, Roberta Pereira; Cardoso, Jefferson Rosa

    2010-03-01

    The objective of this article is to identify the prevalence of mouth breathing in children from an elementary school. 496 questionnaires were answered by 1st and 4th grade children's parents or sponsors in order to identify mouth-breathing. There were questions about habits, sleeping, behavior, eating, personal care and breathing. Mann-Whitney and the Chi-square tests were used to compare the variables between mouth-breathing and nose-breathing among the groups. To measure the exposure effect of the explanatory variables on mouth breathing, the test of logistic regression was used and its magnitude was calculated through Odds Ratio. The statistical significance was set at 5%, and the rate of returned questionnaires was 84.5%. The prevalence of the mouthbreathing over this population was 56.8%. The average age was 7 years old (6-9). There was no significant statistical difference between genders, considering 49.1% male and 50.9% female. The final model of logistic regression identified the variables dribble, sleeps well (negative association) and snores as factors that predict the occurrence of the mouth-breathing. The prevalence of mouthbreathing was similar to related in the literature. The variables dribble, sleeps well (negative association) and snores may be factors that predict the occurrence of mouth-breathing.

  3. Health, social and economical consequences of sleep-disordered breathing

    DEFF Research Database (Denmark)

    Jennum, Poul; Kjellberg, Jakob

    2011-01-01

    The objective direct and indirect costs of sleep-disordered breathing (snoring, sleep apnoea (SA) and obesity hypoventilation syndrome (OHS)) and the treatment are incompletely described.......The objective direct and indirect costs of sleep-disordered breathing (snoring, sleep apnoea (SA) and obesity hypoventilation syndrome (OHS)) and the treatment are incompletely described....

  4. Symptoms of sleep disordered breathing and risk of cancer

    DEFF Research Database (Denmark)

    Christensen, Anne Sofie; Clark, Alice Jessie; Salo, Paula;

    2013-01-01

    Sleep disordered breathing (SDB) has been associated with oxidative stress, inflammation, and altered hormonal levels, all of which could affect the risk of cancer. The aim of the study is to examine if symptoms of SDB including snoring, breathing cessations, and daytime sleepiness affect...

  5. 42 CFR 84.152 - Breathing tube test; minimum requirements.

    Science.gov (United States)

    2010-10-01

    ... Respirators § 84.152 Breathing tube test; minimum requirements. (a)(1) Type A and Type B supplied-air respirators shall employ one or two flexible breathing tubes of the nonkinking type which extend from the... employed on Type C supplied-air respirators of the continuous flow class shall meet the...

  6. 46 CFR 154.1852 - Air breathing equipment.

    Science.gov (United States)

    2010-10-01

    ... 46 Shipping 5 2010-10-01 2010-10-01 false Air breathing equipment. 154.1852 Section 154.1852... STANDARDS FOR SELF-PROPELLED VESSELS CARRYING BULK LIQUEFIED GASES Operations § 154.1852 Air breathing equipment. (a) The master shall ensure that a licensed officer inspects the compressed air...

  7. Measurement of Personal Exposure Using a Breathing Thermal Manikin

    DEFF Research Database (Denmark)

    Brohus, Henrik

    In this paper personal exposure measurements are performed by means of the Breathing Thermal Manikin. Contaminant concentration is measured in a number of locations in the breathing zone and in the inhaled air. Two cases are investigated: exposure to different contaminant sources in a displacement...

  8. Breathing simulator of workers for respirator performance test.

    Science.gov (United States)

    Yuasa, Hisashi; Kumita, Mikio; Honda, Takeshi; Kimura, Kazushi; Nozaki, Kosuke; Emi, Hitoshi; Otani, Yoshio

    2015-01-01

    Breathing machines are widely used to evaluate respirator performance but they are capable of generating only limited air flow patterns, such as, sine, triangular and square waves. In order to evaluate the respirator performance in practical use, it is desirable to test the respirator using the actual breathing patterns of wearers. However, it has been a difficult task for a breathing machine to generate such complicated flow patterns, since the human respiratory volume changes depending on the human activities and workload. In this study, we have developed an electromechanical breathing simulator and a respiration sampling device to record and reproduce worker's respiration. It is capable of generating various flow patterns by inputting breathing pattern signals recorded by a computer, as well as the fixed air flow patterns. The device is equipped with a self-control program to compensate the difference in inhalation and exhalation volume and the measurement errors on the breathing flow rate. The system was successfully applied to record the breathing patterns of workers engaging in welding and reproduced the breathing patterns.

  9. 42 CFR 84.203 - Breathing resistance test; minimum requirements.

    Science.gov (United States)

    2010-10-01

    ... 42 Public Health 1 2010-10-01 2010-10-01 false Breathing resistance test; minimum requirements. 84.203 Section 84.203 Public Health PUBLIC HEALTH SERVICE, DEPARTMENT OF HEALTH AND HUMAN SERVICES... Chemical Cartridge Respirators § 84.203 Breathing resistance test; minimum requirements. (a) Resistance...

  10. Breath hydrogen analysis in patients with ileoanal pouch anastomosis

    DEFF Research Database (Denmark)

    Bruun, E; Meyer, J N; Rumessen, J J;

    1995-01-01

    The possible influence on functional outcomes of hydrogen production in the ileoanal pouch after restorative proctocolectomy was investigated by means of lactulose H2 breath tests. Eight of 15 patients had significant increases in breath hydrogen after 10 g lactulose. One patient declined to part...

  11. Cortisol-sensitive urea transport across the gill basolateral membrane of the gulf toadfish (Opsanus beta).

    Science.gov (United States)

    Rodela, Tamara M; Gilmour, Kathleen M; Walsh, Patrick J; McDonald, M Danielle

    2009-08-01

    Gulf toadfish (Opsanus beta) use a unique pulsatile urea excretion mechanism that allows urea to be voided in large pulses via the periodic insertion or activation of a branchial urea transporter. The precise cellular and subcellular location of the facilitated diffusion mechanism(s) remains unclear. An in vitro basolateral membrane vesicle (BLMV) preparation was used to test the hypothesis that urea movement across the gill basolateral membrane occurs through a cortisol-sensitive carrier-mediated mechanism. Toadfish BLMVs demonstrated two components of urea uptake: a linear element at high external urea concentrations, and a phloretin-sensitive saturable constituent (K(m) = 0.24 mmol/l; V(max) = 6.95 micromol x mg protein(-1) x h(-1)) at low urea concentrations ( 2, further suggestive of carrier-mediated processes. Our data provide evidence that a basolateral urea facilitated transporter accelerates the movement of urea between the plasma and gills to enable the pulsatile excretion of urea. Furthermore, in vivo infusion of cortisol caused a significant 4.3-fold reduction in BLMV urea transport capacity in lab-crowded fish, suggesting that cortisol inhibits the recruitment of urea transporters to the basolateral membrane, which may ultimately affect the size of the urea pulse event in gulf toadfish.

  12. Using Carbon-14 Isotope Tracing to Investigate Molecular Structure Effects of the Oxygenate Dibutyl Maleate on Soot Emissions from a DI Diesel Engine

    Energy Technology Data Exchange (ETDEWEB)

    Buchholz, B A; Mueller, C J; Upatnieks, A; Martin, G C; Pitz, W J; Westbrook, C K

    2004-01-07

    The effect of oxygenate molecular structure on soot emissions from a DI diesel engine was examined using carbon-14 ({sup 14}C) isotope tracing. Carbon atoms in three distinct chemical structures within the diesel oxygenate dibutyl maleate (DBM) were labeled with {sup 14}C. The {sup 14}C from the labeled DBM was then detected in engine-out particulate matter (PM), in-cylinder deposits, and CO{sub 2} emissions using accelerator mass spectrometry (AMS). The results indicate that molecular structure plays an important role in determining whether a specific carbon atom either does or does not form soot. Chemical-kinetic modeling results indicate that structures that produce CO{sub 2} directly from the fuel are less effective at reducing soot than structures that produce CO before producing CO{sub 2}. Because they can follow individual carbon atoms through a real combustion process, {sup 14}C isotope tracing studies help strengthen the connection between actual engine emissions and chemical-kinetic models of combustion and soot formation/oxidation processes.

  13. Influence of condensation temperature on selected exhaled breath parameters

    Directory of Open Access Journals (Sweden)

    Manini Paola

    2005-09-01

    Full Text Available Abstract Background The effects of changes in cooling temperature on biomarker levels in exhaled breath condensate have been little investigated. The aim of the study was to test the effect of condensation temperature on the parameters of exhaled breath condensate and the levels of selected biomarkers. Methods Exhaled breath condensate was collected from 24 healthy subjects at temperatures of -10, -5, 0 and +5 C degrees. Selected parameters (condensed volume and conductivity and biomarkers (hydrogen peroxide, malondialdehyde were measured. Results There was a progressive increase in hydrogen peroxide and malondialdehyde concentrations, and condensate conductivity as the cooling temperature increased; total condensate volume increased as the cooling temperature decreased. Conclusion The cooling temperature of exhaled breath condensate collection influenced selected biomarkers and potential normalizing factors (particularly conductivity in different ways ex vivo. The temperature of exhaled breath condensate collection should be controlled and reported.

  14. Transgenic Restoration of Urea Transporter A1 Confers Maximal Urinary Concentration in the Absence of Urea Transporter A3.

    Science.gov (United States)

    Klein, Janet D; Wang, Yanhua; Mistry, Abinash; LaRocque, Lauren M; Molina, Patrick A; Rogers, Richard T; Blount, Mitsi A; Sands, Jeff M

    2016-05-01

    Urea has a critical role in urinary concentration. Mice lacking the inner medullary collecting duct (IMCD) urea transporter A1 (UT-A1) and urea transporter A3 (UT-A3) have very low levels of urea permeability and are unable to concentrate urine. To investigate the role of UT-A1 in the concentration of urine, we transgenically expressed UT-A1 in knockout mice lacking UT-A1 and UT-A3 using a construct with a UT-A1 gene that cannot be spliced to produce UT-A3. This construct was inserted behind the original UT-A promoter to yield a mouse expressing only UT-A1 (UT-A1(+/+)/UT-A3(-/-)). Western blot analysis demonstrated UT-A1 in the inner medulla of UT-A1(+/+)/UT-A3(-/-) and wild-type mice, but not in UT-A1/UT-A3 knockout mice, and an absence of UT-A3 in UT-A1(+/+)/UT-A3(-/-) and UT-A1/UT-A3 knockout mice. Immunohistochemistry in UT-A1(+/+)/UT-A3(-/-) mice also showed negative UT-A3 staining in kidney and other tissues and positive UT-A1 staining only in the IMCD. Urea permeability in isolated perfused IMCDs showed basal permeability in the UT-A1(+/+)/UT-A3(-/-) mice was similar to levels in wild-type mice, but vasopressin stimulation of urea permeability in wild-type mice was significantly greater (100% increase) than in UT-A1(+/+)/UT-A3(-/-) mice (8% increase). Notably, basal urine osmolalities in both wild-type and UT-A1(+/+)/UT-A3(-/-) mice increased upon overnight water restriction. We conclude that transgenic expression of UT-A1 restores basal urea permeability to the level in wild-type mice but does not restore vasopressin-stimulated levels of urea permeability. This information suggests that transgenic expression of UT-A1 alone in mice lacking UT-A1 and UT-A3 is sufficient to restore urine-concentrating ability.

  15. Aspiration tests in aqueous foam using a breathing simulator

    Energy Technology Data Exchange (ETDEWEB)

    Archuleta, M.M.

    1995-12-01

    Non-toxic aqueous foams are being developed by Sandia National Laboratories (SNL) for the National Institute of Justice (NIJ) for use in crowd control, cell extractions, and group disturbances in the criminal justice prison systems. The potential for aspiration of aqueous foam during its use and the resulting adverse effects associated with complete immersion in aqueous foam is of major concern to the NIJ when examining the effectiveness and safety of using this technology as a Less-Than-Lethal weapon. This preliminary study was designed to evaluate the maximum quantity of foam that might be aspirated by an individual following total immersion in an SNL-developed aqueous foam. A.T.W. Reed Breathing simulator equipped with a 622 Silverman cam was used to simulate the aspiration of an ammonium laureth sulfate aqueous foam developed by SNL and generated at expansion ratios in the range of 500:1 to 1000:1. Although the natural instinct of an individual immersed in foam is to cover their nose and mouth with a hand or cloth, thus breaking the bubbles and decreasing the potential for aspiration, this study was performed to examine a worst case scenario where mouth breathing only was examined, and no attempt was made to block foam entry into the breathing port. Two breathing rates were examined: one that simulated a sedentary individual with a mean breathing rate of 6.27 breaths/minute, and one that simulated an agitated or heavily breathing individual with a mean breathing rate of 23.7 breaths/minute. The results of this study indicate that, if breathing in aqueous foam without movement, an air pocket forms around the nose and mouth within one minute of immersion.

  16. Síntese e controle de qualidade da ureia enriquecida em 13C para diagnóstico da Helicobacterpylori (HP Synthesis and quality control of 13C-enriched urea for Helicobacter pylori (HP diagnosis

    Directory of Open Access Journals (Sweden)

    Carlos R. Sant Ana Filho

    2013-01-01

    Full Text Available The aim of the study was to synthesize the urea (13CO(NH22, with 99% 13C atoms, and to perform a quality analysis for the diagnosis (breath test of Helicobacter pylori. Furthermore, the process was submitted to economic analysis. The reaction was performed in a stainless steel reactor, lined with polytetrafluoroethylene, under low pressure and temperature. The synthesis method was shown to be appropriate (2.35 g; 81.9% yield, evidenced by physico-chemical and microbiological results, according to Brazilian legislation. The production and diagnosis costs were competitive compared with national and international market values, rendering this a valuable tool in clinical medicine.

  17. The Influence of Age on Interaction between Breath-Holding Test and Single-Breath Carbon Dioxide Test.

    Science.gov (United States)

    Trembach, Nikita; Zabolotskikh, Igor

    2017-01-01

    Introduction. The aim of the study was to compare the breath-holding test and single-breath carbon dioxide test in evaluation of the peripheral chemoreflex sensitivity to carbon dioxide in healthy subjects of different age. Methods. The study involved 47 healthy volunteers between ages of 25 and 85 years. All participants were divided into 4 groups according to age: 25 to 44 years (n = 14), 45 to 60 years (n = 13), 60 to 75 years (n = 12), and older than 75 years (n = 8). Breath-holding test was performed in the morning before breakfast. The single-breath carbon dioxide (SB-CO2) test was performed the following day. Results. No correlation was found between age and duration of breath-holding (r = 0.13) and between age and peripheral chemoreflex sensitivity to CO2 (r = 0.07). In all age groups there were no significant differences in the mean values from the breath-holding test and peripheral chemoreflex sensitivity tests. In all groups there was a strong significant inverse correlation between breath-holding test and SB-CO2 test. Conclusion. A breath-holding test reflects the sensitivity of the peripheral chemoreflex to carbon dioxide in healthy elderly humans. Increasing age alone does not alter the peripheral ventilatory response to hypercapnia.

  18. Urea Transporter Inhibitors: En Route to New Diuretics

    Science.gov (United States)

    Sands, Jeff M.

    2013-01-01

    Summary A selective urea transporter UT-A1 inhibitor would be a novel type of diuretic, likely with less undesirable side-effects than conventional diureticssince it acts on the last portion of the nephron. Esteva-Font et al. (2013) develop suchan inhibitor by using a clever high-throughput screening assay, and document its selectivity. . PMID:24210002

  19. New urea-absorbing polymers for artificial kidney machines

    Science.gov (United States)

    Mueller, W. A.; Hsu, G. C.; Marsh, H. E., Jr.

    1975-01-01

    Etherified polymer is made from modified cellulose derivative which is reacted with periodate. It will absorb 2 grams of urea per 100 grams of polymer. Indications are that polymers could be used to help remove uremic wastes in artificial kidneys, or they could be administered orally as therapy for uremia.

  20. Synthesis, Characterization, and Sensitivity Analysis of Urea Nitrate (UN)

    Science.gov (United States)

    2015-04-01

    Wolf E, Tamiri T. Recovery and deterction of urea nitrate in traces. Journal of Forensic Science. 2007;52:1284. 5. Oxley JC, Smith JL, Naik S. Moran...reagents. Indian Journal of Chemistry . Section A: Inorganic, Bioinorgainc, Phsical, Theoretical & Anlystical Chemistry . 2004;43A:307. 8. Oxley J, Smith JL

  1. Urea in sugarcane-based diets for dairy cows

    Directory of Open Access Journals (Sweden)

    Alberto Magno Ferreira Santiago

    2013-06-01

    Full Text Available We evaluated the effect of adding four levels (0, 4, 8 and 12 g/kg, as fed of a mixture (9:1 of urea and ammonium sulfate (UAs to sugarcane on feed intake and digestibility, productive performance and metabolism of nitrogen compounds of dairy cows. Twelve multiparous Holstein cows (12.6±0.5 kg/d of milk, 225±90 days in milk were distributed in three 4 × 4 Latin squares, receiving diets with the same amount of nitrogen (125 g crude protein/kg of dry matter. Concentrate feed was supplied at a ratio of 1 kg for each 3 kg of milk produced. The sugarcane presented 21.9 ºBrix. The level of UAs did not affect intake, total digestibility of diet components, milk production or milk components. Increasing UAs level linearly increased concentration of plasma urea nitrogen (PUN, urinary excretion of nitrogen and contribution of non-urea nitrogen in the urinary excretion and linearly reduced milk production/urinary excretion of nitrogen ratio. In spite of the linear increase of PUN with increased urea, the maximum value observed (14.31 mg/dL was below the threshold value of 20 mg/dL, above which reproductive function may be compromised. In diets with sugarcane for dairy cows with production below 15 kg/day, the UAs level may be raised from 0 to 12 g/kg natural matter without impairing performance.

  2. Prebiotic formation of polyamino acids in molten urea

    Science.gov (United States)

    Mita, H.; Nomoto, S.; Terasaki, M.; Shimoyama, A.; Yamamoto, Y.

    2005-04-01

    It is important for research into the origins of life to elucidate polyamino acid formation under prebiotic conditions. Only a limited set of amino acids has been reported to polymerize thermally. In this paper we demonstrate a novel thermal polymerization mechanism in a molten urea of alkylamino acids (i.e. glycine, alanine, β-alanine, α-aminobutyric acid, valine, norvaline, leucine and norleucine), which had been thought to be incapable of undergoing thermal polymerization. Also, aspartic acid was found to polymerize in molten urea at a lower temperature than that at which aspartic acid alone had previously been thermally polymerized. Individual oligomers produced in heating experiments on urea-amino acid mixtures were analysed using a liquid chromatograph mass spectrometer. Major products in the reaction mixture were three different types of polyamino acid derivatives: N-carbamoylpolyamino acids, polyamino acids containing a hydantoin ring at the N-terminal position and unidentified derivatives with molecular weights that were greater by 78 than those of the corresponding peptide forms. The polymerization reaction occurred by taking advantage of the high polarity of molten urea as well as its dehydrating ability. Under the presumed prebiotic conditions employed here, many types of amino acids were thus revealed to undergo thermal polymerization.

  3. Urea modified cottonseed protein adhesive for wood composite products

    Science.gov (United States)

    Cottonseed protein has the potential to be used as renewable and environmentally friendly adhesives in wood products industry. However, the industry application was limited by its low mechanical properties, low water resistance and viscosity. In this work, urea modified cottonseed protein adhesive w...

  4. Effect of Urea on Activity and Conformation of a Glycoprotein

    Institute of Scientific and Technical Information of China (English)

    WEI Xiang; WANG Xiaoyun; ZHOU Bo; ZHOU Haimeng

    2006-01-01

    The changes of the activity and conformation of Aspergillus niger phytase in urea were detected by farultraviolet circular dichroism (CD) spectra, fluorescence spectra, and enzyme activity assays. The results show that no enzyme activity can be detected after phytase is incubated for 10 h in 3.0 mol/L urea, even though at this urea concentration, less than 20% of the tertiary and secondary structures in the native enzyme changed. The inactivation reaction kinetics is found to be a monophasic first-order reaction, but the unfolding is a biphasic process consisting of two first-order reactions. The inactivation rates of the free enzyme and the substrate-enzyme complex are much faster than the conformational changes during urea denaturation. All of the results indicate that, as a glycoprotein, phytase's activity is strongly dependent on its conformational integrity. The phytase active sites seem to be located in a limited region in the molecule and display more conformational fragility and flexibility to denaturants than enzyme molecular structure as a whole.

  5. Tailoring of analytical performances of urea biosensors using nanomaterials

    Science.gov (United States)

    Nouira, W.; Barhoumi, H.; Maaref, A.; Jaffrézic Renault, N.; Siadat, M.

    2013-03-01

    This paper is a contribution to the study of enzymatic sensors based on nanoparticles of iron oxide (FeNPs). Urease enzyme was immobilized on FeNPs using layer-by-layer (LbL) deposition method. FeNPs were first coated with polyelectrolytes (PE): Poly (allylamine hydrochloride), PAH and Poly (sodium 4-styrenesulfonate), PSS for enzyme immobilization and then with enzyme. It has been confirmed through zeta potential measurements of FeNPs that the enzyme is immobilized on the surface. We evaluated the sensitivity of biosensors for urea by potentiometric and capacitive measurements on silicon / silica / FeNP-LBL-urease structures. The recorded capacity-potential curves (C-V) show a significant shift of flat band potential towards negative potentials in the presence of urea, the observed values of sensitivity vary between 30 and 40 mV/p[urea]. It has been shown that the proposed method for the immobilization of urease can increase the dynamic range of urea detection (10-4M to 10-1M) compared to the immobilization of urease without FeNP (10-3.5 M to 10-2.5 M). When the number of PAH-PSS layers was increased the sensitivity of detection was modified. This effect is due to partial inhibition of the enzyme in presence of FeNPs, which was shown by measurements in homogeneous phase.

  6. Reduction in slow intercompartmental clearance of urea during dialysis

    Energy Technology Data Exchange (ETDEWEB)

    Bowsher, D.J.; Krejcie, T.C.; Avram, M.J.; Chow, M.J.; Del Greco, F.; Atkinson, A.J. Jr.

    1985-04-01

    The kinetics of urea and inulin were analyzed in five anesthetized dogs during sequential 2-hour periods before, during, and after hemodialysis. The distribution of both compounds after simultaneous intravenous injection was characterized by three-compartment models, and the total volumes of urea (0.66 +/- 0.05 L/kg) and inulin (0.19 +/- 0.01 L/kg) distribution were similar to expected values for total body water and extravascular space, respectively. Intercompartmental clearances calculated before dialysis were used to estimate blood flows to the fast and slow equilibrating compartments. In agreement with previous results, the sum of these flows was similar to cardiac output, averaging 101% of cardiac output measured before dialysis (range 72% to 135%). Dialysis was accompanied by reductions in the slow intercompartmental clearances of urea (81%) and inulin (47%), which reflected a 90% attenuation in blood flow supplying the slow equilibrating compartments. This was estimated to result in a 10% average reduction in the efficiency with which urea was removed by dialysis (range 2.0% to 16.4%). Mean arterial pressure fell by less than 5% during dialysis, but total peripheral resistance increased by 47% and cardiac output fell by 35%. In the postdialysis period, total peripheral resistance and cardiac output returned toward predialysis values, but blood flow to the slow equilibrating peripheral compartment was still reduced by 80%. These changes parallel activation of the renin-angiotensin system, but further studies are required to establish causality.

  7. New biomedical polyurethane ureas with high tear strengths

    NARCIS (Netherlands)

    deGroot, JH; deVrijer, R; Wildeboer, BS; Spaans, CS; Pennings, AJ

    1997-01-01

    Biodegradable polyurethanes ureas (PUU) were synthesized by a two step polymerization. First a poly (epsilon-caprolactone) prepolymer was terminated with three different diisocyanates: lysinediisocyanate (LDI), 1,6-hexanediisocyanate (HDI) and 1,4-butanediisocyanate (BDI). Second the prepolymers wer

  8. Dietary management of urea cycle disorders : European practice

    NARCIS (Netherlands)

    Adam, S.; Almeida, M. F.; Assoun, M.; Baruteau, J.; Bernabei, S. M.; Bigot, S.; Champion, H.; Daly, A.; Dassy, M.; Dawson, S.; Dixon, M.; Dokoupil, K.; Dubois, S.; Dunlop, C.; Evans, S.; Eyskens, F.; Faria, A.; Favre, E.; Ferguson, C.; Goncalves, C.; Gribben, J.; Heddrich-Ellerbrok, M.; Jankowski, C.; Janssen-Regelink, R.; Jouault, C.; Laguerre, C.; Le Verge, S.; Link, R.; Lowry, S.; Luyten, K.; MacDonald, A.; Maritz, C.; McDowell, S.; Meyer, U.; Micciche, A.; Robertson, L. V.; Rocha, J. C.; Rohde, C.; Saruggia, I.; Sjoqvist, E.; Stafford, J.; Terry, A.; Thom, R.; Vande Kerckhove, K.; van Rijn, M.; van Teeffelen-Heithoff, A.; van Wegberg, A.; van Wyk, K.; Vasconcelos, C.; Vestergaard, H.; Webster, D.; White, F. J.; Wildgoose, J.; Zweers, H.; Robert, M.

    2013-01-01

    Background: There is no published data comparing dietary management of urea cycle disorders (UCD) in different countries. Methods: Cross-sectional data from 41 European Inherited Metabolic Disorder (IMD) centres (17 UK, 6 France, 5 Germany, 4 Belgium, 4 Portugal, 2 Netherlands, 1 Denmark, 1 Italy, 1

  9. Dietary management of urea cycle disorders: European practice.

    NARCIS (Netherlands)

    Adam, S.; Almeida, M.F.; Assoun, M.; Baruteau, J.; Bernabei, S.M.; Bigot, S.; Champion, H.; Daly, A.; Dassy, M.; Dawson, S.; Dixon, M.; Dokoupil, K.; Dubois, S.; Dunlop, C.; Evans, S.; Eyskens, F.; Faria, A.; Favre, E.; Ferguson, C.; Goncalves, C.; Gribben, J.; Heddrich-Ellerbrok, M.; Jankowski, C.; Janssen-Regelink, R.; Jouault, C.; Laguerre, C.; Verge, S. Le; Link, R.; Lowry, S.; Luyten, K.; Macdonald, A.; Maritz, C.; McDowell, S.; Meyer, U.; Micciche, A.; Robert, M.; Robertson, L.V.; Rocha, J.C.; Rohde, C.; Saruggia, I.; Sjoqvist, E.; Stafford, J.; Terry, A.; Thom, R.; nde Kerckhove, K. Va; Rijn, M. van de; Teeffelen-Heithoff, A. van; Wegberg, A.v.; Wyk, K. van; Vasconcelos, C.; Vestergaard, H.; Webster, D.; White, F.J.; Wildgoose, J.; Zweers, H.

    2013-01-01

    BACKGROUND: There is no published data comparing dietary management of urea cycle disorders (UCD) in different countries. METHODS: Cross-sectional data from 41 European Inherited Metabolic Disorder (IMD) centres (17 UK, 6 France, 5 Germany, 4 Belgium, 4 Portugal, 2 Netherlands, 1 Denmark, 1 Italy, 1

  10. Encapsulated Urea-Kaolinite Nanocomposite for Controlled Release Fertilizer Formulations

    Directory of Open Access Journals (Sweden)

    Siafu Ibahati Sempeho

    2015-01-01

    Full Text Available Urea controlled release fertilizer (CRF was prepared via kaolinite intercalation followed by gum arabic encapsulation in an attempt to reduce its severe losses associated with dissolution, hydrolysis, and diffusion. Following the beneficiation, the nonkaolinite fraction decreased from 39.58% to 0.36% whereas the kaolinite fraction increased from 60.42% to 99.64%. The X-ray diffractions showed that kaolinite was a major phase with FCC Bravais crystal lattice with particle sizes ranging between 14.6 nm and 92.5 nm. The particle size varied with intercalation ratios with methanol intercalated kaolinite > DMSO-kaolinite > urea-kaolinite (KPDMU. Following intercalation, SEM analysis revealed a change of order from thick compact overlapping euhedral pseudohexagonal platelets to irregular booklets which later transformed to vermiform morphology and dispersed euhedral pseudohexagonal platelets. Besides, dispersed euhedral pseudohexagonal platelets were seen to coexist with blocky-vermicular booklets. In addition, a unique brain-form agglomeration which transformed into roundish particles mart was observed after encapsulation. The nanocomposites decomposed between 48 and 600°C. Release profiles showed that 100% of urea was released in 97 hours from KPDMU while 87% was released in 150 hours from the encapsulated nanocomposite. The findings established that it is possible to use Pugu kaolinite and gum arabic biopolymer to prepare urea CRF formulations.

  11. Photoresponsive dithienylethene-urea-based organogels with "reversed" behavior

    NARCIS (Netherlands)

    Akazawa, Masako; Uchida, Kingo; de Jong, Jaap J. D.; Areephong, Jetsuda; Stuart, Marc; Caroli, Giuseppe; Browneb, Wesley R.; Feringa, Ben L.; Browne, Wesley R.

    2008-01-01

    Dithienylperhydrocyclopentene-bisurea-based low molecular weight gelators are described that function as photoresponsive organogels that show a remarkable gel-to-liquid transition upon irradiation. The two series of derivatives, with and without alkyl spacers between the urea hydrogen bonding groups

  12. Nitrogen utilization and transformation in red soil fertilized with urea and ryegrass

    Institute of Scientific and Technical Information of China (English)

    WuGang; HeZhen-Li

    1998-01-01

    The influence of fertilization with urea and ryegrass on nitrogen utilization and transformation in red soil has been studied by using 15N tracer method.When urea and ryegrass were applied alone or in combination,the percentage of N uptaken by ryegrass from labelled urea was 3 and 1.7 times that from labelled ryegrass for the application rate of 200mgN.kg-1 and 100mgN.kg-1,respectively;combining application of ryegrass and ureareduced uptake of urea N and increased uptake of ryegrass N by ryegrass plant,but the percentage of N residued in soil increased for urea and decreased for ryegrass.when urea and ryegrass were applied alone,the percentage of N residued in soil from labelled ryegrass was more than 69% while that from labelled urea was less than 25%,and much more ryegrass N was incorporated into humus than urea N.

  13. Synthesis and Performance of Polyurethane Coated Urea as Slow/controlled Release Fertilizer

    Institute of Scientific and Technical Information of China (English)

    LI Qingshan; WU Shu; RU Tiejun; WANG Limin; XING Guangzhong; WANG Jinming

    2012-01-01

    Polyurethane coated urea slow/controlled release fertilizer was prepared based on urea granules,isocyanate,polyols and paraffin.Isocyanate reacted with polyols to synthesize the polyurethane skin layer on urea granules surface.Paraffin serves as a lubricant during syntheses of polyurethane skin layers.The structure and nutrient release characteristics of the polyurethane skin layers were investigated by FTIR,SEM and TG.Urea nitrogen slow-release behavior of the polyurethane coated urea was tested.The experimental results indicated that compact and dense polyurethane skin layers with a thickness of 10-15 μm were formed on urea surface,the urea nitrogen slow-release time can reach 40-50 days.Paraffin proves to play a key role in inhibiting water to penetrate into urea,but excessive addition would decrease the polyurethane crosslinking density.

  14. Sleep-disordered breathing and stroke.

    Science.gov (United States)

    Ali, Latisha K; Avidan, Alon Y

    2008-01-01

    Sleep and stroke have an important and fascinating interaction. Patients with sleep-disordered breathing present with cardiovascular heart disease, cognitive decline, and increased risk of stroke. Stroke adversely affects sleep and factors such as prolonged immobilization, chronic pain, nocturnal hypoxia, and depression, which can also adversely impact sleep quality. Obstructive sleep apnea (OSA), one of the most common and serious sleep disturbances, manifests itself in almost 50% of all stroke patients. Sleep apnea patients who experience a stroke may be at a greater impairment in their rehabilitation potential and have increased risk of secondary stroke and mortality. Given these factors, the practicing neurologist should possess the skills to appropriately recognize, rapidly diagnose, and properly manage stroke patients with OSA.

  15. Respiratory pattern of diaphragmatic breathing and pilates breathing in COPD subjects

    Directory of Open Access Journals (Sweden)

    Karina M. Cancelliero-Gaiad

    2014-08-01

    Full Text Available BACKGROUND: Diaphragmatic breathing (DB is widely used in pulmonary rehabilitation (PR of patients with chronic obstructive pulmonary disease (COPD, however it has been little studied in the scientific literature. The Pilates breathing (PB method has also been used in the rehabilitation area and has been little studied in the scientific literature and in COPD. OBJECTIVES: To compare ventilatory parameters during DB and PB in COPD patients and healthy adults. METHOD: Fifteen COPD patients (COPD group and fifteen healthy patients (healthy group performed three types of respiration: natural breathing (NB, DB, and PB, with the respiratory pattern being analyzed by respiratory inductive plethysmography. The parameters of time, volume, and thoracoabdominal coordination were evaluated. After the Shapiro-Wilk normality test, ANOVA was applied followed by Tukey's test (intragroup analysis and Student's t-test (intergroup analysis; p<0.05. RESULTS: DB promoted increase in respiratory volumes, times, and SpO2 as well as decrease in respiratory rate in both groups. PB increased respiratory volumes in healthy group, with no additional benefits of respiratory pattern in the COPD group. With respect to thoracoabdominal coordination, both groups presented higher asynchrony during DB, with a greater increase in the healthy group. CONCLUSIONS: DB showed positive effects such as increase in lung volumes, respiratory motion, and SpO2 and reduction in respiratory rate. Although there were no changes in volume and time measurements during PB in COPD, this breathing pattern increased volumes in the healthy subjects and increased oxygenation in both groups. In this context, the acute benefits of DB are emphasized as a supporting treatment in respiratory rehabilitation programs.

  16. Oral breathing: new early treatment protocol

    Directory of Open Access Journals (Sweden)

    Gloria Denotti

    2014-01-01

    Full Text Available Oral breathing is a respiratory dysfunction that affects approximately 10-15% of child population. It is responsable of local effects and systemic effects, both immediate and long-term. They affect the growth of the subject and his physical health in many ways: pediatric, psycho-behavioral and cognitive. The etiology is multifactorial. It’s important the establishment of a vicious circle involving more areas and it is essential to stop it as soon as possible. In order to correct this anomaly, the pediatric dentist must be able to make a correct diagnosis to treat early the disfunction and to avoid the onset of cascade mechanisms. Who plays a central role is the pediatrician who first and frequently come into contact with little patients. He can identify the anomalies, and therefore collaborate with other specialists, including the dentist. The key aspect that guides us in the diagnosis, and allows us to identify the oral respirator, is the “adenoid facies”. The purpose of the study is to highlight the importance and benefits of an early and multidisciplinary intervention (pediatric, orthopedic-orthodontic-functional. A sample of 20 patients was selected with the following inclusion criteria: mouth breathing, transverse discrepancy > 4 mm, early mixed dentition, central and lateral permenent incisors, overjet increased, lip and nasal incompetence, snoring and/or sleep apnea episodes. The protocol of intervention includes the use of the following devices and procedures: a maxillary rapid expander (to correct the transverse discrepancy, to increase the amplitude of the upper respiratory airway and to reduce nasal resistances tract in association with myo-functional devices (nasal stimulator and oral obturator. They allow the reconstruction of a physiological balance between the perioral musculature and tongue, the acquisition of nasal and lips competence and the reduction of overjet. This protocol speeds up and stabilizes the results. The

  17. Effects of slow-release urea on ruminal digesta characteristics and growth performance in beef steers

    DEFF Research Database (Denmark)

    Taylor-Edwards, C C; Hibbard, G; Kitts, S E;

    2009-01-01

    Two experiments were conducted to evaluate the effects of slow urea (SRU) versus feed-grade urea on ruminal metabolite characteristics in steers and DMI, gain, and G:F in growing beef steers.......Two experiments were conducted to evaluate the effects of slow urea (SRU) versus feed-grade urea on ruminal metabolite characteristics in steers and DMI, gain, and G:F in growing beef steers....

  18. SERUM AND PAROTID FLUIS UREA-LEVELS IN UNREALOADED HEALTHY YOUNG ADULTS

    Science.gov (United States)

    Forty-four healthy young adult male subjects were given oral doses of urea, and parotid fluid and serum urea levels were studied for 1 to 3 hours. A...highly significant correlation between urea in serum and in parotid fluid (r equals 0.982) was found. The indication was that, with flow rate...carefully controlled, parotid fluid could be used interchangeably with serum in urea determination, regardless of the magnitude of the blood concentration. (Author)

  19. 76 FR 35405 - Solid Urea From the Russian Federation: Preliminary Results of Antidumping Duty Administrative...

    Science.gov (United States)

    2011-06-17

    ... International Trade Administration Solid Urea From the Russian Federation: Preliminary Results of Antidumping... review of the antidumping duty order on solid urea from the Russian Federation (Russia). The review... solid urea from the Union of Soviet Socialist Republics (Soviet Union). See Antidumping Duty Order;...

  20. Comparison of amino acid oxidation and urea metabolism in haemodialysis patients during fasting and meal intake

    NARCIS (Netherlands)

    Veeneman, JM; Kingma, HA; Stellaard, F; de Jong, PE; Reijngoud, DJ; Huisman, RM

    2004-01-01

    Background. The PNA (protein equivalent of nitrogen appearance) is used to calculate protein intake from urea kinetics. One of the essential assumptions in the calculation of PNA is that urea accumulation in haemodialysis (HD) patients is equivalent to amino acid oxidation. However, urea is hydrolys

  1. 75 FR 51440 - Solid Urea from the Russian Federation: Final Results of Antidumping Duty Administrative Review

    Science.gov (United States)

    2010-08-20

    ... International Trade Administration Solid Urea from the Russian Federation: Final Results of Antidumping Duty... of the administrative review of the antidumping duty order on solid urea from the Russian Federation. The solid urea subject to this review was produced and exported by MCC EuroChem (EuroChem). The...

  2. GC-MS DETERMINATION OF RATIOS OF STABLE-ISOTOPE LABELED TO NATURAL UREA USING [(CN2)-C-13-N-15]UREA FOR STUDYING UREA KINETICS IN SERUM AND AS A MEANS TO VALIDATE ROUTINE METHODS FOR THE QUANTITATIVE ASSAY OF UREA IN DIALYSATE

    NARCIS (Netherlands)

    WOLTHERS, BG; TEPPER, T; WITHAG, A; NAGEL, GT; DEHAAN, THY; VANLEEUWEN, JJ; STEGEMAN, CA; HUISMAN, RM

    1994-01-01

    A GC-MS determination of urea in serum or spent dialysate is described, using (CN2)-C-13-N-15-labelled urea and assaying the area ratio of labelled to natural urea by mass fragmentographic monitoring of fragments m/e 153 and 156, after its eventual conversion into the trimethylsilylether-derivative

  3. 78 FR 46571 - Solid Urea From the Russian Federation: Preliminary Results of Antidumping Duty Administrative...

    Science.gov (United States)

    2013-08-01

    ... International Trade Administration Solid Urea From the Russian Federation: Preliminary Results of Antidumping... review of the antidumping duty order on solid urea from the Russian Federation (Russia). The period of...: Scope of the Order The merchandise subject to the order is solid urea. The product is...

  4. 75 FR 51055 - Propionic Acid and Salts, and Urea Sulfate; Registration Review Proposed Decisions; Notice of...

    Science.gov (United States)

    2010-08-18

    ... AGENCY Propionic Acid and Salts, and Urea Sulfate; Registration Review Proposed Decisions; Notice of... urea sulfate and opens a public comment period on the proposed decisions. Registration review is EPA's.... Urea sulfate is used as a desiccant on ] cotton. No food crop uses remain and all tolerances for...

  5. 78 FR 67335 - Solid Urea From the Russian Federation: Final Results of Antidumping Duty Administrative Review...

    Science.gov (United States)

    2013-11-12

    ... International Trade Administration Solid Urea From the Russian Federation: Final Results of Antidumping Duty... duty order on solid urea from the Russian Federation (Russia). For the final results, we continue to... solid urea from Russia.\\1\\ We invited interested parties to comment on the Preliminary Results....

  6. 40 CFR 418.30 - Applicability; description of the urea subcategory.

    Science.gov (United States)

    2010-07-01

    ... 40 Protection of Environment 28 2010-07-01 2010-07-01 true Applicability; description of the urea...) EFFLUENT GUIDELINES AND STANDARDS FERTILIZER MANUFACTURING POINT SOURCE CATEGORY Urea Subcategory § 418.30 Applicability; description of the urea subcategory. The provisions of this subpart are applicable to...

  7. 75 FR 78243 - Propionic Acid and Salts, Urea Sulfate, Methidathion, and Methyl Parathion; Registration Review...

    Science.gov (United States)

    2010-12-15

    ... AGENCY Propionic Acid and Salts, Urea Sulfate, Methidathion, and Methyl Parathion; Registration Review... pesticides propionic acid and salts, case no. 4078, urea sulfate, case no. 7213, methidathion, case no. 0034... pesticides in the table below--propionic acid and salts, case 4078, urea sulfate, case no. 7213,...

  8. 21 CFR 177.1900 - Urea-formaldehyde resins in molded articles.

    Science.gov (United States)

    2010-04-01

    ... 21 Food and Drugs 3 2010-04-01 2009-04-01 true Urea-formaldehyde resins in molded articles. 177... for Use as Basic Components of Single and Repeated Use Food Contact Surfaces § 177.1900 Urea-formaldehyde resins in molded articles. Urea-formaldehyde resins may be safely used as the food-contact...

  9. 40 CFR 721.9920 - Urea, (hexahydro-6-methyl-2-oxopyrimidinyl)-.

    Science.gov (United States)

    2010-07-01

    ... 40 Protection of Environment 30 2010-07-01 2010-07-01 false Urea, (hexahydro-6-methyl-2... Specific Chemical Substances § 721.9920 Urea, (hexahydro-6-methyl-2-oxopyrimidinyl)-. (a) Chemical substance and significant new uses subject to reporting. (1) The chemical substance urea,...

  10. 76 FR 66690 - Solid Urea From the Russian Federation: Final Results of Antidumping Duty Administrative Review

    Science.gov (United States)

    2011-10-27

    ... International Trade Administration Solid Urea From the Russian Federation: Final Results of Antidumping Duty... of the administrative review of the antidumping duty order on solid urea from the Russian Federation. The solid urea subject to this review was produced and exported by MCC EuroChem (EuroChem). The...

  11. 76 FR 78885 - Solid Urea From the Russian Federation and Ukraine: Continuation of Antidumping Duty Orders

    Science.gov (United States)

    2011-12-20

    ... International Trade Administration Solid Urea From the Russian Federation and Ukraine: Continuation of... International Trade Commission (ITC) that revocation of the antidumping duty orders on solid urea from the... orders on solid urea from Russia and Ukraine,\\1\\ pursuant to section 751(c) of the Tariff Act of 1930,...

  12. Use of natural and biobased materials for controlled-release of urea in water: Environmental applications

    Science.gov (United States)

    Urea pearls were encapsulated in cloisite-based matrices using different natural materials (lignin, beeswax and latex) to control the release of urea over time. It was found that all cloisite-based fertilizer tablets showed better release profiles than neat urea tablets. The best release profile was...

  13. The permeability of red blood cells to chloride, urea and water

    DEFF Research Database (Denmark)

    Brahm, Jesper

    2013-01-01

    This study extends permeability (P) data on chloride, urea and water in red blood cells (RBC), and concludes that the urea transporter (UT-B) does not transport water. P of chick, duck, Amphiuma means, dog and human RBC to (36)Cl(-), (14)C-urea and (3)H2O was determined under self...

  14. Hyperpolarized (13) C,(15) N2 -Urea MRI for assessment of the urea gradient in the porcine kidney

    DEFF Research Database (Denmark)

    Hansen, Esben S S; Stewart, Neil J; Wild, Jim M;

    2016-01-01

    function in healthy porcine kidneys resembling the human physiology. METHODS: Five healthy female Danish domestic pigs (weight 30 kg) were scanned at 3 Tesla (T) using a (13) C 3D balanced steady-state MR pulse sequence following injection of hyperpolarized (13) C,(15) N2 -urea via a femoral vein catheter...

  15. Breathing abnormalities in a female mouse model of Rett syndrome.

    Science.gov (United States)

    Johnson, Christopher M; Cui, Ningren; Zhong, Weiwei; Oginsky, Max F; Jiang, Chun

    2015-09-01

    Rett syndrome (RTT) is a female neurodevelopmental disease with breathing abnormalities. To understand whether breathing defects occur in the early lives of a group of female Mecp2(+/-) mice, a mouse model of RTT, and what percentage of mice shows RTT-like breathing abnormality, breathing activity was measured by plethysmography in conscious mice. Breathing frequency variation and central apnea in a group of Mecp2(+/-) females displayed a distribution pattern similar to Mecp2(-/Y) males, while the rest resembled the wild-type mice. Similar results were obtained using the k-mean clustering statistics analysis. With two independent methods, about 20% of female Mecp2(+/-) mice showed RTT-like breathing abnormalities that began as early as 3 weeks of age in the Mecp2(+/-) mice, and were suppressed with 3% CO2. The finding that only a small proportion of Mecp2(+/-) mice develops RTT-like breathing abnormalities suggests incomplete allele inactivation in the RTT-model Mecp2(+/-) mice.

  16. Voluntary control of breathing does not alter vagal modulation of heart rate

    Science.gov (United States)

    Patwardhan, A. R.; Evans, J. M.; Bruce, E. N.; Eckberg, D. L.; Knapp, C. F.

    1995-01-01

    Variations in respiratory pattern influence the heart rate spectrum. It has been suggested, hence, that metronomic respiration should be used to correctly assess vagal modulation of heart rate by using spectral analysis. On the other hand, breathing to a metronome has been reported to increase heart rate spectral power in the high- or respiratory frequency region; this finding has led to the suggestion that metronomic respiration enhances vagal tone or alters vagal modulation of heart rate. To investigate whether metronomic breathing complicates the interpretation of heart rate spectra by altering vagal modulation, we recorded the electrocardiogram and respiration from eight volunteers during three breathing trials of 10 min each: 1) spontaneous breathing (mean rate of 14.4 breaths/min); 2) breathing to a metronome at the rate of 15, 18, and 21 breaths/min for 2, 6, and 2 min, respectively; and 3) breathing to a metronome at the rate of 18 breaths/min for 10 min. Data were also collected from eight volunteers who breathed spontaneously for 20 min and breathed metronomically at each subject's mean spontaneous breathing frequency for 20 min. Results from the three 10-min breathing trials showed that heart rate power in the respiratory frequency region was smaller during metronomic breathing than during spontaneous breathing. This decrease could be explained fully by the higher breathing frequencies used during trials 2 and 3 of metronomic breathing. When the subjects breathed metronomically at each subject's mean breathing frequency, the heart rate powers during metronomic breathing were similar to those during spontaneous breathing. Our results suggest that vagal modulation of heart rate is not altered and vagal tone is not enhanced during metronomic breathing.

  17. Distribution and Biomarker of Carbon-14 Labeled Fullerene C60 ([14C(U)]C60) in Pregnant and Lactating Rats and their Offspring after Maternal Intravenous Exposure

    Science.gov (United States)

    Snyder, Rodney W.; Fennell, Timothy R.; Wingard, Christopher J.; Mortensen, Ninell P.; Holland, Nathan A.; Shannahan, Jonathan H.; Pathmasiri, Wimal; Lewin, Anita H.; Sumner, Susan C. J.

    2015-01-01

    A comprehensive distribution study was conducted in pregnant and lactating rats exposed to a suspension of uniformly carbon-14 labeled C60 ([14C(U)]C60). Rats were administered [14C(U)]C60 (~0.2 mg [14C(U)]C60/kg body weight) or 5% polyvinylpyrrolidone (PVP)-saline vehicle via a single tail vein injection. Pregnant rats were injected on gestation day (GD) 11 (terminated with fetuses after either 24h or 8d), GD15 (terminated after 24h or 4d), or GD18 (terminated after 24h). Lactating rats were injected on postnatal day 8 and terminated after 24h, 3d or 11d. The distribution of radioactivity in pregnant dams was influenced by both the state of pregnancy and time of termination after exposure. The percentage of recovered radioactivity in pregnant and lactating rats was highest in liver and lungs. Radioactivity was quantitated in over 20 tissues. Radioactivity was found in placenta and in fetuses of pregnant dams, and in the milk of lactating rats and in pups. Elimination of radioactivity was <2% in urine and feces at each time point. Radioactivity remained in blood circulation up to 11 days after [14C(U)]C60 exposure. Biomarkers of inflammation, cardiovascular injury and oxidative stress were measured to study the biological impacts of [14C(U)]C60 exposure. Oxidative stress were elevated in female pups of exposed dams. Metabolomics analysis of urine showed that [14C(U)]C60 exposure to pregnant rats impacted the pathways of vitamin B, regulation of lipid and sugar metabolism and aminoacyl-tRNA biosynthesis. This study demonstrated that [14C(U)]C60 crosses the placenta at all stages of pregnancy examined, and is transferred to pups via milk. PMID:26081520

  18. Evaluation of the Determination of Free Urea in Water-Soluble Liquid Fertilizers Containing Urea and Ureaforms by Urease and HPLC Methods.

    Science.gov (United States)

    Hojjatie, Michael M; Abrams, Dean

    2015-01-01

    Currently there are three AOAC Official Methods for the determination of urea in fertilizers. AOAC Official Method 959.03, Urea in Fertilizers, Urease Method, First Action 1959, Final Action 1960, is based on the use of fresh commercial 1% urease solution, or preparation of such solution from urease powder in water, or from jack bean meal in water. AOAC Official Method 983.01, Urea and Methyleneureas (Water-Soluble) in Fertilizers, First Action 1983, Final Action 1984, is based on LC with a refractive index detector using water as the mobile phase and a C18 column. AOAC Official Method 2003.14, Determination of Urea in Water- Soluble Urea-Formaldehyde Fertilizer Products and in Aqueous Urea Solutions, First Action 2003, Final Action 2008, is based on LC with a UV detector using acetonitrile-water (85+15, v/v) mobile phase and a propylamine column. The urea method, AOAC Official Method 959.03, is very much dependent on the nature of the urease enzyme. The method was developed in 1960 and used for simple urea fertilizer solutions. With the advent of complex fertilizer compositions, especially with the class of liquid triazone fertilizers and water-soluble urea forms, the analyses of free urea in these fertilizers by the urease method is often inaccurate and inconsistent. AOAC Official Method 983.01 is not always reliable due to the interference of some of the components of these fertilizers, and due to the fact that the use of water as the mobile phase does not always separate the free urea from other components. AOAC Official Method 2003.14 was subjected to ring test studies that showed it could be used for the determination of "free urea" in these classes of fertilizers with good accuracy and precision.

  19. Hydrogen and methane breath tests for evaluation of resistant carbohydrates

    DEFF Research Database (Denmark)

    Rumessen, J J

    1992-01-01

    This review considers in detail the background, principles, techniques, limitations and advantages of the hydrogen and methane breath tests. Resistant food carbohydrates, defined as dietary carbohydrates partly or totally escaping small intestinal assimilation, are fermented in the human colon...... carbohydrates. Methane breath tests may supplement the information gained from hydrogen measurements, but further evaluations are needed. The hydrogen breath technique is rapid, simple and non-invasive as well as non-radioactive. It may be carried out in a large number of intact individuals under physiological...

  20. Lactose malabsorption during gastroenteritis, assessed by the hydrogen breath test.

    OpenAIRE

    Gardiner, A J; Tarlow, M J; Sutherland, I T; Sammons, H G

    1981-01-01

    Thirty-eight infants and young children with gastroenteritis were investigated for lactose malabsorption. Each of them was given an oral lactose load of either 0.5 g/kg or 2 g/kg after which breath hydrogen excretion was measured, and each was observed to see if he had clinical symptoms of lactose intolerance. Only one patient, given 2 g/kg lactose, had clinical intolerance. His breath hydrogen excretion however was negative. Three of 18 patients given 0.5 g/kg lactose had positive breath hyd...

  1. Alcoholic Hepatitis Markedly Decreases the Capacity for Urea Synthesis.

    Directory of Open Access Journals (Sweden)

    Emilie Glavind

    Full Text Available Data on quantitative metabolic liver functions in the life-threatening disease alcoholic hepatitis are scarce. Urea synthesis is an essential metabolic liver function that plays a key regulatory role in nitrogen homeostasis. The urea synthesis capacity decreases in patients with compromised liver function, whereas it increases in patients with inflammation. Alcoholic hepatitis involves both mechanisms, but how these opposite effects are balanced remains unclear. Our aim was to investigate how alcoholic hepatitis affects the capacity for urea synthesis. We related these findings to another measure of metabolic liver function, the galactose elimination capacity (GEC, as well as to clinical disease severity.We included 20 patients with alcoholic hepatitis and 7 healthy controls. The urea synthesis capacity was quantified by the functional hepatic nitrogen clearance (FHNC, i.e., the slope of the linear relationship between the blood α-amino nitrogen concentration and urea nitrogen synthesis rate during alanine infusion. The GEC was determined using blood concentration decay curves after intravenous bolus injection of galactose. Clinical disease severity was assessed by the Glasgow Alcoholic Hepatitis Score and Model for End-Stage Liver Disease (MELD score.The FHNC was markedly decreased in the alcoholic hepatitis patients compared with the healthy controls (7.2±4.9 L/h vs. 37.4±6.8 L/h, P<0.01, and the largest decrease was observed in those with severe alcoholic hepatitis (4.9±3.6 L/h vs. 9.9±4.9 L/h, P<0.05. The GEC was less markedly reduced than the FHNC. A negative correlation was detected between the FHNC and MELD score (rho = -0.49, P<0.05.Alcoholic hepatitis markedly decreases the urea synthesis capacity. This decrease is associated with an increase in clinical disease severity. Thus, the metabolic failure in alcoholic hepatitis prevails such that the liver cannot adequately perform the metabolic up-regulation observed in other stressful

  2. Alcoholic Hepatitis Markedly Decreases the Capacity for Urea Synthesis

    Science.gov (United States)

    Glavind, Emilie; Aagaard, Niels Kristian; Grønbæk, Henning; Møller, Holger Jon; Orntoft, Nikolaj Worm; Vilstrup, Hendrik; Thomsen, Karen Louise

    2016-01-01

    Background and Aim Data on quantitative metabolic liver functions in the life-threatening disease alcoholic hepatitis are scarce. Urea synthesis is an essential metabolic liver function that plays a key regulatory role in nitrogen homeostasis. The urea synthesis capacity decreases in patients with compromised liver function, whereas it increases in patients with inflammation. Alcoholic hepatitis involves both mechanisms, but how these opposite effects are balanced remains unclear. Our aim was to investigate how alcoholic hepatitis affects the capacity for urea synthesis. We related these findings to another measure of metabolic liver function, the galactose elimination capacity (GEC), as well as to clinical disease severity. Methods We included 20 patients with alcoholic hepatitis and 7 healthy controls. The urea synthesis capacity was quantified by the functional hepatic nitrogen clearance (FHNC), i.e., the slope of the linear relationship between the blood α-amino nitrogen concentration and urea nitrogen synthesis rate during alanine infusion. The GEC was determined using blood concentration decay curves after intravenous bolus injection of galactose. Clinical disease severity was assessed by the Glasgow Alcoholic Hepatitis Score and Model for End-Stage Liver Disease (MELD) score. Results The FHNC was markedly decreased in the alcoholic hepatitis patients compared with the healthy controls (7.2±4.9 L/h vs. 37.4±6.8 L/h, P<0.01), and the largest decrease was observed in those with severe alcoholic hepatitis (4.9±3.6 L/h vs. 9.9±4.9 L/h, P<0.05). The GEC was less markedly reduced than the FHNC. A negative correlation was detected between the FHNC and MELD score (rho = -0.49, P<0.05). Conclusions Alcoholic hepatitis markedly decreases the urea synthesis capacity. This decrease is associated with an increase in clinical disease severity. Thus, the metabolic failure in alcoholic hepatitis prevails such that the liver cannot adequately perform the metabolic up

  3. Effect of time duration of ruminal urea infusions on ruminal ammonia concentrations and portal-drained visceral extraction of arterial urea-N in lactating Holstein cows

    DEFF Research Database (Denmark)

    Røjen, Betina Amdisen; Kristensen, Niels Bastian

    2012-01-01

    concentration was observed. The portal flux of urea-N was not affected by treatment (i.e., even the combination of low ruminal ammonia and high arterial urea-N concentration with 6-h INF was not used by the cow to increase the uptake of urea-N across the PDV). Arterial urea-N extraction across the PDV......The effects of a 6 versus 24h ruminal urea infusion in lactating dairy cows fed a basal diet deficient in N on ruminal ammonia concentration, arterial urea-N concentration, net portal-drained viscera (PDV) urea-N flux, arterial urea-N extraction across the PDV, and renal urea-N kinetics were...... investigated. Three Danish Holstein cows fitted with ruminal cannulas and permanent indwelling catheters in major splanchnic blood vessels were randomly allocated to a 3 × 3 Latin square design with 21-d periods. Treatments were ventral ruminal infusion of water for 24h (water INF), 24-h infusion of 15g...

  4. Whole-heart magnetic resonance coronary angiography with multiple breath-holds and automatic breathing-level tracking

    Science.gov (United States)

    Kuhara, Shigehide; Ninomiya, Ayako; Okada, Tomohisa; Kanao, Shotaro; Kamae, Toshikazu; Togashi, Kaori

    2010-05-01

    Whole-heart (WH) magnetic resonance coronary angiography (MRCA) studies are usually performed during free breathing while monitoring the position of the diaphragm with real-time motion correction. However, this results in a long scan time and the patient's breathing pattern may change, causing the study to be aborted. Alternatively, WH MRCA can be performed with multiple breath-holds (mBH). However, one problem in the mBH method is that patients cannot hold their breath at the same position every time, leading to image degradation. We have developed a new WH MRCA imaging method that employs both the mBH method and automatic breathing-level tracking to permit automatic tracking of the changes in breathing or breath-hold levels. Evaluation of its effects on WH MRCA image quality showed that this method can provide high-quality images within a shorter scan time. This proposed method is expected to be very useful in clinical WH MRCA studies.

  5. Chelate effects in sulfate binding by amide/urea-based ligands.

    Science.gov (United States)

    Jia, Chuandong; Wang, Qi-Qiang; Begum, Rowshan Ara; Day, Victor W; Bowman-James, Kristin

    2015-07-01

    The influence of chelate and mini-chelate effects on sulfate binding was explored for six amide-, amide/amine-, urea-, and urea/amine-based ligands. Two of the urea-based hosts were selective for SO4(2-) in water-mixed DMSO-d6 systems. Results indicated that the mini-chelate effect provided by a single urea group with two NH binding sites appears to provide enhanced binding over two amide groups. Furthermore, additional urea binding sites incorporated into the host framework appeared to overcome to some extent competing hydration effects with increasing water content.

  6. Effect of urea on protein separation by ion-exchange chromatography.

    Science.gov (United States)

    Khademi, Fatemeh; Mostafaie, Ali

    2010-05-01

    Ion-exchange chromatography (IEC) is the most frequently used chromatographic technique for the separation of proteins and peptides. In this article, the effects of urea on IEC separation of kiwifruit actinidin, egg white and urinary proteins were examined. The purity and relative amount of each protein in different conditions (in the presence or absence of urea) were compared with each other. The three parameters, including resolution, selectivity and efficiency of column in the presence of urea, were calculated and compared with the absence of urea. The results revealed that urea improved the purity of proteins and the resolution, selectivity and efficiency of IEC in separation of studied proteins.

  7. Utilization of labelled urea in Helicobacter pylori eradication study by Espinheira Santa; Utilizacao de ureia marcada no estudo da erradicacao do Helicobacter pylori pela Espinheira Santa

    Energy Technology Data Exchange (ETDEWEB)

    Chausson, Yvon [Centro de Desenvolvimento da Tecnologia Nuclear (CDTN), Belo Horizonte, MG (Brazil); Coelho, Luiz Gonzaga Vaz; Passos, Maria do Carmo Friche; Andrade, Angela Almeida Magalhaes [Minas Gerais Univ., Belo Horizonte, MG (Brazil). Hospital das Clinicas; Paiva Leriza, Duilio de; Paula Castro, Luiz de [Minas Gerais Univ., Belo Horizonte, MG (Brazil). Faculdade de Farmacia

    1995-12-31

    Maytenus ilicifolia, Espinheira Santa, is usually used to treat some gastric diseases, in special duodenal ulcer, in agreement with the medical literature. The aim of this work was to verify the efficiency of those leaves in such disease. It was selected a group of volunteers with ulcer caused by Helicobacter pylori (Hp) confirmed by Urea Breath Test (UBT). It was administered to all patients one capsule having 300 mg of dry extract of the leaves 20 minutes before the UBT. The capsule went on being administered during a week three times a day. At the end of this period two tests were applied to evaluate the Hp eradication: one 12 hours just after the treatment and another after one month. The results indicated that the antibiotic action was not confirmed. (author). 4 refs., 1 fig.

  8. Salting-Out of Methane in the Aqueous Solutions of Urea and Glycine-Betaine.

    Science.gov (United States)

    Dixit, Mayank Kumar; Siddique, Asrar A; Tembe, B L

    2015-08-27

    We have studied the hydrophobic association and solvation of methane molecules in aqueous solutions of urea and glycine betaine (GB). We have calculated the potentials of mean force (PMFs) between methane molecules in water, aqueous GB, aqueous urea and aqueous urea-GB mixtures. The PMFs and equilibrium constants indicate that both urea and GB increase the hydrophobic association of methane. Calculation of thermodynamic parameters shows that the association of methane is stabilized by entropy whereas solvation is favored by enthalpy. In the case of the water-urea-GB mixture, both hydrophobic association and solvation are stabilized by entropy. From the investigation of radial distribution functions, running coordination numbers and excess coordination numbers, we infer that both urea and GB are preferentially excluded from methane surface in the mixtures of osmolytes and methane is preferentially solvated by water molecules in all the mixtures. The favorable exclusion of both urea and GB from the methane surface suggests that both urea and GB increase the interaction between methane molecules, i.e., salting-out of methane. We observe that addition of both urea and GB to water enhances local water structure. The calculated values of diffusion constants of water also suggest enhanced water-water interactions in the presence of urea and GB. The calculated free energies of methane in these mixtures show that methane is less soluble in the mixtures of urea and GB than in water. The data on solvation free energies support the observations obtained from the PMFs of methane molecules.

  9. Polar or apolar--the role of polarity for urea-induced protein denaturation.

    Directory of Open Access Journals (Sweden)

    Martin C Stumpe

    2008-11-01

    Full Text Available Urea-induced protein denaturation is widely used to study protein folding and stability; however, the molecular mechanism and driving forces of this process are not yet fully understood. In particular, it is unclear whether either hydrophobic or polar interactions between urea molecules and residues at the protein surface drive denaturation. To address this question, here, many molecular dynamics simulations totalling ca. 7 micros of the CI2 protein in aqueous solution served to perform a computational thought experiment, in which we varied the polarity of urea. For apolar driving forces, hypopolar urea should show increased denaturation power; for polar driving forces, hyperpolar urea should be the stronger denaturant. Indeed, protein unfolding was observed in all simulations with decreased urea polarity. Hyperpolar urea, in contrast, turned out to stabilize the native state. Moreover, the differential interaction preferences between urea and the 20 amino acids turned out to be enhanced for hypopolar urea and suppressed (or even inverted for hyperpolar urea. These results strongly suggest that apolar urea-protein interactions, and not polar interactions, are the dominant driving force for denaturation. Further, the observed interactions provide a detailed picture of the underlying molecular driving forces. Our simulations finally allowed characterization of CI2 unfolding pathways. Unfolding proceeds sequentially with alternating loss of secondary or tertiary structure. After the transition state, unfolding pathways show large structural heterogeneity.

  10. Mice lacking urea transporter UT-B display depression-like behavior.

    Science.gov (United States)

    Li, Xin; Ran, Jianhua; Zhou, Hong; Lei, Tianluo; Zhou, Li; Han, Jingyan; Yang, Baoxue

    2012-02-01

    Urea transporter B is one of urea transporters that selectively transport urea driven by urea gradient across membrane and expressed abundantly in brain. To determine the physiological role of UT-B in brain, UT-B localization, urea concentration, tissue morphology of brain, and behavioral phenotypes were studied in UT-B heterozygous mice via UT-B null mice. UT-B mRNA was expressed in olfactory bulb, cortex, caudate nucleus, hippocampus and hypothalamus of UT-B heterozygous mice. UT-B null mice exhibited depression-like behavior, with urea accumulation, nitric oxide reduction, and selective neuronal nitric oxide synthase level increase in hippocampus. After acute urea loading, the urea level increased, NO production decreased in hippocampus from both types of mice. Moreover, urea level was higher, and NO concentration was lower consistently in UT-B null hippocampus than that in heterozygous hippocampus. In vitro, 25 mM urea inhibited NO production too. Furthermore, UT-B knockout induced a long-lasting notable decrease in regional cerebral blood flow and altered morphology, such as loss of neurons in CA3 region, swelling, and membranous myelin-like structure formation within myelinated and unmyelinated fibers in hippocampus. These results suggest that urea accumulation in the hippocampus induced by UT-B deletion can cause depression-like behavior, which possibly attribute to disturbance in NOS/NO system.

  11. Syllable-Related Breathing in Infants in the Second Year of Life

    Science.gov (United States)

    Parham, Douglas F.; Buder, Eugene H.; Oller, D. Kimbrough; Boliek, Carol A.

    2011-01-01

    Purpose: This study explored whether breathing behaviors of infants within the 2nd year of life differ between tidal breathing and breathing supporting single unarticulated syllables and canonical/articulated syllables. Method: Vocalizations and breathing kinematics of 9 infants between 53 and 90 weeks of age were recorded. A strict selection…

  12. 46 CFR 78.47-27 - Self-contained breathing apparatus.

    Science.gov (United States)

    2010-10-01

    ... 46 Shipping 3 2010-10-01 2010-10-01 false Self-contained breathing apparatus. 78.47-27 Section 78... Markings for Fire and Emergency Equipment, Etc. § 78.47-27 Self-contained breathing apparatus. Lockers or spaces containing self-contained breathing apparatus shall be marked “SELF-CONTAINED BREATHING APPARATUS.”...

  13. The effect of urea pretreatment on the formaldehyde emission and properties of straw particleboard

    Institute of Scientific and Technical Information of China (English)

    Hojat Hematabadi; Rabi Behrooz

    2012-01-01

    For manufacturing low-formaldehyde emission particleboard from wheat straw and urea-formaldehyde (UF) resins using urea treatment for indoor environments,we investigated the influence of urea treatment on the formaldehyde emission,physical and mechanical properties of the manufactured particleboard.Wheat straws were treated at three levels of urea concentration (5%,10%,15%) and 95℃ as holding temperature.Wheat straw particleboards were manufactured using hot press at 180℃ and 3 MPa with two types of UF adhesive (UF-45,UF-91).Then the formaldehyde emission values,physical properties and mechanical properties were considered.The results show that the formaldehyde emission value was decreased by increasing urea concentration.Furthermore,the results indicate that the specimens under urea treatment have better mechanical and physical properties compared with control specimens.Also specimens under urea treatment at 10% concentration and UF-91 type adhesive have the most optimum physical and mechanical strength.

  14. Data of 1H/13C NMR spectra and degree of substitution for chitosan alkyl urea

    Directory of Open Access Journals (Sweden)

    Jing Wang

    2016-06-01

    Full Text Available The data shown in this article are related to the subject of an article in Carbohydrate Polymers, entitled “Synthesis and characterization of chitosan alkyl urea” [1]. 1H NMR and 13C NMR spectra of chitosan n-octyl urea, chitosan n-dodecyl urea and chitosan cyclohexyl urea are displayed. The chemical shifts of proton and carbon of glucose skeleton in these chitosan derivatives are designated in detail. Besides, 1H NMR spectra of chitosan cyclopropyl urea, chitosan tert-butyl urea, chitosan phenyl urea and chitosan N,N-diethyl urea and the estimation of the degree of substitution are also presented. The corresponding explanations can be found in the above-mentioned article.

  15. Determination of Carbon-14 in environmental samples by mixing 14CO{sub 2} with a liquid scintillator; Determinacion de carbono-14 en muestras ambientales por incorporacion de 14CO{sub 2} a un centelleador liquido

    Energy Technology Data Exchange (ETDEWEB)

    Garcia, M. R.; Gomez, V.; Heras, M. C.; Beltran, M. A.

    1990-07-01

    A method for the determination of Carbon-14 (14CO2) in environmental samples has been developed. The method use the direct absorption of the carbon dioxide into Carbosorb, followed with incorporation of the mixture (Carbosorb-CO2) to the liquid scintillator. The results obtained to apply this method and the benzene synthesis, usual in our laboratory, are discussed and compared. The method of collection of atmospheric samples is also described. (Author) 10 refs.

  16. COPD: When You Learn More, You'll Breathe Better

    Science.gov (United States)

    Skip Navigation Bar Home Current Issue Past Issues COPD: When You Learn More, You'll Breathe Better ... Trial to Look at Home Oxygen Therapy for COPD The National Heart, Lung, and Blood Institute (NHLBI) ...

  17. Taking Her Breath Away: The Rise of COPD in Women

    Science.gov (United States)

    ... Disparities Taking Her Breath Away: The Rise of COPD in Women Disparities in Lung Health Series More ... the U.S. live with chronic obstructive pulmonary disease (COPD), which includes chronic bronchitis and emphysema. Millions more ...

  18. Bounded Gain of Energy on the Breathing Circle Billiard

    CERN Document Server

    Oliffson-Kamphorst, S; Kamphorst, Sylvie Oliffson; Carvalho, Sonia Pinto de

    1998-01-01

    The Breathing Circle is a 2-dimensional generalization of the Fermi Accelerator. It is shown that the billiard map associated to this model has invariant curves in phase space, implying that any particle will have bounded gain of energy.

  19. Exhaled breath condensate: methodological recommendations and unresolved questions.

    NARCIS (Netherlands)

    Horvath, I.; Hunt, J.; Barnes, P.J.; Alving, K.; Antczak, A.; Baraldi, E.; Becher, G.; Beurden, W.J.C van; Corradi, M.; Dekhuijzen, P.N.R.; Dweik, R.A.; Dwyer, T.; Effros, R.; Erzurum, S.; Gaston, B.; Gessner, C.; Greening, A.; Ho, L.P.; Hohlfeld, J.; Jobsis, Q.; Laskowski, D.; Loukides, S.; Marlin, D.; Montuschi, P.; Olin, A.C.; Redington, A.E.; Reinhold, P.; Rensen, E.L. van; Rubinstein, I.; Silkoff, P.; Toren, K.; Vass, G.; Vogelberg, C.; Wirtz, H.

    2005-01-01

    Collection of exhaled breath condensate (EBC) is a noninvasive method for obtaining samples from the lungs. EBC contains large number of mediators including adenosine, ammonia, hydrogen peroxide, isoprostanes, leukotrienes, nitrogen oxides, peptides and cytokines. Concentrations of these mediators a

  20. Training Studies with Compressed Air Breathing Apparatus – Methodology, Exercises

    Directory of Open Access Journals (Sweden)

    Buks Roberts

    2015-11-01

    Full Text Available The current article describes topics ranging from the respiratory physiology and the structure of compressed air breathing apparatus to the performance of practical training exercises in an unbreathable environment (hereinafter referred to as UE.

  1. Atmospheric Breathing Electric Thruster for Planetary Exploration Project

    Data.gov (United States)

    National Aeronautics and Space Administration — This study will investigate the development of an atmosphere-breathing electric propulsion solar-powered vehicle to explore planets such as Mars. The vehicle would...

  2. CO2 Washout Capability with Breathing Manikin Project

    Data.gov (United States)

    National Aeronautics and Space Administration — The intent of this particular project was to perform the following:Provide a breathing capability to be integrated into existing EC5 Ventilation Lab Suited...

  3. Fear of suffocation alters respiration during obstructed breathing.

    Science.gov (United States)

    Pappens, Meike; Smets, Elyn; Van Den Bergh, Omer; Van Diest, Ilse

    2012-06-01

    We aimed to investigate whether fear of suffocation predicts healthy persons' respiratory and affective responses to obstructed breathing as evoked by inspiratory resistive loads. Participants (N = 27 women, ages between 18 and 21 years) completed the Fear of Suffocation scale and underwent 16 trials in which an inspiratory resistive load of 15 cmH(2)O/l/s (small) or 40 cmH(2)O/l/s (large) was added to the breathing circuit for 40 s. Fear of suffocation was associated with higher arousal ratings for both loads. Loaded breathing was associated with a decrease in minute ventilation, but progressively less so for participants scoring higher on fear of suffocation when breathing against the large load. The present findings document a potentially panicogenic mechanism that may maintain and worsen respiratory discomfort in persons with fear of suffocation.

  4. Cardiac output in exercise by impedance cardiography during breath holding and normal breathing.

    Science.gov (United States)

    Du Quesnay, M C; Stoute, G J; Hughson, R L

    1987-01-01

    Estimation of cardiac output by impedance cardiography (QZ) in exercise during normal breathing (NB) has been limited by motion artifact. Our objective was to obtain readable impedance cardiograms on five subjects during upright cycle exercise at 0, 50, 100, 150, and 200 W to permit comparisons of QZ during NB, expiratory breath hold (EXP) and inspiratory breath hold (INSP). Q was also determined using an equilibration CO2 rebreathing method [Q(RB)]. QZ during NB exceeded EXP QZ at 100, 150, and 200 W, and exceeded INSP QZ at 100 W (P less than 0.05). The low EXP QZ values were due to a significantly lower stroke volume at 100, 150, and 200 W (P less than 0.05). For the INSP QZ at 100 W, heart rate was lower than during EXP (P less than 0.05). Regression of QZ (NB) against Q(RB) resulted in a linear relationship (r = 0.93) over the range of Q = 7-26 1/min. The slope of the regression differed significantly from 1.0 (P less than 0.05). We conclude that QZ values obtained during EXP or INSP should not be assumed to represent QZ during NB, at least at work rates greater than 50 W. A consequence of the linear relationship between QZ(NB) and Q(RB) over the range of 0-200 W is that estimates of CO2 rebreathing cardiac output can be obtained by impedance cardiography if QZ is adjusted using an appropriate empirical factor.

  5. Insomnia and sleep-related breathing disorders.

    Science.gov (United States)

    Wickwire, Emerson M; Collop, Nancy A

    2010-06-01

    Insomnia disorder and obstructive sleep apnea are the two most common sleep disorders among adults. Historically, these conditions have been conceptualized as orthogonal, or insomnia has been considered a symptom of sleep apnea. Insomnia researchers have sought to exclude participants at risk for sleep-related breathing disorders (SRBD), and vice versa. In recent years, however, there has been a growing recognition of co-occurring insomnia disorder and SRBD and interest in the prevalence, consequences, and treatment of the two conditions when they co-occur. Although plagued by inconsistent diagnostic criteria and operational definitions, evidence from clinical and research samples consistently suggests high rates of comorbidity between the two disorders. More important, insomnia disorder and SRBD have additive negative effects. To date, only a few studies have explored the combined or sequential treatment of the conditions. Results support the importance of an integrated, interdisciplinary approach to sleep medicine. This article reviews the empirical literature to date and provides clinical recommendations as well as suggestions for future research.

  6. Sleep disordered breathing in facioscapulohumeral muscular dystrophy.

    Science.gov (United States)

    Della Marca, Giacomo; Frusciante, Roberto; Dittoni, Serena; Vollono, Catello; Buccarella, Cristina; Iannaccone, Elisabetta; Rossi, Monica; Scarano, Emanuele; Pirronti, Tommaso; Cianfoni, Alessandro; Mazza, Salvatore; Tonali, Pietro A; Ricci, Enzo

    2009-10-15

    Facioscapulohumeral muscular dystrophy (FSHD) is one of the most frequent forms of muscular dystrophy. The aims of this study were: 1) to evaluate the prevalence of sleep disordered breathing (SDB) in patients with FSHD; 2) to define the sleep-related respiratory patterns in FSHD patients with SDB; and 3) to find the clinical predictors of SDB. Fifty-one consecutive FSHD patients were enrolled, 23 women, mean age 45.7+/-12.3 years (range: 26-72). The diagnosis of FSHD was confirmed by genetic tests. All patients underwent medical and neurological evaluations, subjective evaluation of sleep and full-night laboratory-based polysomnography. Twenty patients presented SDB: 13 presented obstructive apneas, four presented REM related oxygen desaturations and three showed a mixed pattern. Three patients needed positive airways pressure. SDB was not related to the severity of the disease. Body mass index, neck circumference and daytime sleepiness did not allow prediction of SDB. In conclusion, the results suggest a high prevalence of SDB in patients with FSHD. The presence of SDB does not depend on the clinical severity of the disease. SDB is often asymptomatic, and no clinical or physical measure can reliably predict its occurrence. A screening of SDB should be included in the clinical assessment of FSHD.

  7. FBG sensor of breathing encapsulated into polydimethylsiloxane

    Science.gov (United States)

    Fajkus, Marcel; Nedoma, Jan; Siska, Petr; Vasinek, Vladimir

    2016-10-01

    The technology of Fiber Bragg grating (FBG) belongs to the most widespread fiber-optic sensors. They are used for measuring a large number of physical and chemical quantities. Small size, immunity to electromagnetic interference, high sensitivity and a principle of information encoding about the measurement value into spectral characteristics causes usability of FBG sensors in medicine for monitoring vital signs such as temperature, blood pressure, pulse, and respiration. An important factor is the use of an inert material for the encapsulation of Bragg gratings in this area. A suitable choice is a polydimethylsiloxane (PDMS) elastomer having excellent thermal and elastic properties. Experimental results describe the creation of FBG sensory prototype for monitoring breathing in this paper. The sensor is realized by encapsulation of Bragg grating into PDMS. The FBG sensor is mounted on the elastic contact strap which encircles the chest of the patient. This tension leads to a spectral shift of the reflected light from the FBG. For measurement, we used a broadband light source Light-Emitting Diode (LED) with central wavelength 1550 nm and optical spectrum analyzer.

  8. Underwater breathing: the mechanics of plastron respiration

    Science.gov (United States)

    Flynn, M. R.; Bush, John W. M.

    The rough, hairy surfaces of many insects and spiders serve to render them water-repellent; consequently, when submerged, many are able to survive by virtue of a thin air layer trapped along their exteriors. The diffusion of dissolved oxygen from the ambient water may allow this layer to function as a respiratory bubble or , and so enable certain species to remain underwater indefinitely. Maintenance of the plastron requires that the curvature pressure balance the pressure difference between the plastron and ambient. Moreover, viable plastrons must be of sufficient area to accommodate the interfacial exchange of O2 and CO2 necessary to meet metabolic demands. By coupling the bubble mechanics, surface and gas-phase chemistry, we enumerate criteria for plastron viability and thereby deduce the range of environmental conditions and dive depths over which plastron breathers can survive. The influence of an external flow on plastron breathing is also examined. Dynamic pressure may become significant for respiration in fast-flowing, shallow and well-aerated streams. Moreover, flow effects are generally significant because they sharpen chemical gradients and so enhance mass transfer across the plastron interface. Modelling this process provides a rationale for the ventilation movements documented in the biology literature, whereby arthropods enhance plastron respiration by flapping their limbs or antennae. Biomimetic implications of our results are discussed.

  9. Urea sensors based on PVC membrane pH electrode.

    Science.gov (United States)

    Głab, S; Koncki, R; Kopczewska, E; Wałcerz, I; Hulanicki, A

    1994-07-01

    Several procedures of urease immobilization on the surface of the polymeric membrane pH electrode with tri-n-dodecylamine as a neutral carrier were compared. The best results were obtained for the urea sensor with covalently bound urease. The sensor characteristics including the effect of buffer, pH and concentration and the effect of stirring rate are presented. These effects are in good agreement with theoretical expectations.

  10. Reverse osmosis membrane of high urea rejection properties. [water purification

    Science.gov (United States)

    Johnson, C. C.; Wydeven, T. J. (Inventor)

    1980-01-01

    Polymeric membranes suitable for use in reverse osmosis water purification because of their high urea and salt rejection properties are prepared by generating a plasma of an unsaturated hydrocarbon monomer and nitrogen gas from an electrical source. A polymeric membrane is formed by depositing a polymer of the unsaturated monomer from the plasma onto a substrate, so that nitrogen from the nitrogen gas is incorporated within the polymer in a chemically combined form.

  11. Orphan drugs in development for urea cycle disorders: current perspectives

    Directory of Open Access Journals (Sweden)

    Häberle J

    2014-09-01

    Full Text Available Johannes Häberle,1 Shawn E McCandless2 1Division of Metabolism and Children's Research Center, University Children's Hospital Zurich, Zurich, Switzerland; 2Center for Human Genetics, University Hospitals Case Medical Center, and Department of Genetics and Genome Sciences, Case Western Reserve University, Cleveland, OH, USA Abstract: The urea cycle disorders are caused by deficiency of one of the six hepatic enzymes or two transporters involved in detoxification of ammonia. The resulting hyperammonemia causes severe brain injury unless aggressive steps are taken to reduce the accumulation of ammonia, which is thought to be the most toxic metabolite. This review describes the current state of chronic management of urea cycle disorders, focusing on new and emerging therapies. Management strategies include the mainstay of treatment, namely dietary protein restriction and supplementation with l-arginine or l-citrulline. Several currently approved medications utilize and enhance alternative pathways of waste nitrogen excretion (sodium benzoate, sodium phenylacetate, sodium phenylbutyrate in several formulations, and glycerol phenylbutyrate, working through conjugation of the drug to either glycine (in the case of benzoate or glutamine, the products of which are excreted in the urine. Carglumic acid activates the first committed step of conversion of ammonia to urea, carbamoylphosphate synthetase, and thus effectively treats defective synthesis of the endogenous activator, N-acetylglutamate, whether due to genetic defects or biochemical inhibition of the N-acetylglutamate synthase enzyme. Approaches to neuroprotection during episodes of hyperammonemia are discussed, including the use of controlled hypothermia (brain cooling, as well as proposed, but as yet untested, pharmacologic therapies. Finally, cell-based therapies, including liver transplantation, infusion of fresh or cryopreserved hepatocytes, use of stem cells, and new approaches to gene

  12. A stochastic model for an urea decomposition system

    Directory of Open Access Journals (Sweden)

    VSS Yadavalli

    2005-12-01

    Full Text Available Availability is an important measure in describing the performance of a system. The availability of a decomposition process in an urea production system in the fertilizer industry is considered in this paper. The system contains four subsystems and is supported by a standby unit. An estimation study of the steady state availability of the system is performed and illustrated by means of a numerical example.

  13. Encapsulated Urea-Kaolinite Nanocomposite for Controlled Release Fertilizer Formulations

    OpenAIRE

    Siafu Ibahati Sempeho; Hee Taik Kim; Egid Mubofu; Alexander Pogrebnoi; Godlisten Shao; Askwar Hilonga

    2015-01-01

    Urea controlled release fertilizer (CRF) was prepared via kaolinite intercalation followed by gum arabic encapsulation in an attempt to reduce its severe losses associated with dissolution, hydrolysis, and diffusion. Following the beneficiation, the nonkaolinite fraction decreased from 39.58% to 0.36% whereas the kaolinite fraction increased from 60.42% to 99.64%. The X-ray diffractions showed that kaolinite was a major phase with FCC Bravais crystal lattice with particle sizes ranging betwee...

  14. Mechanism of Microencapsulation with Urea-Formaldehyde Polymer

    OpenAIRE

    Rochmadi .; Agus Prasetya; Wahyu Hasokowati

    2010-01-01

    Problem statement: Microcapsule is one of important fine chemical products in the current chemical industries. Better understanding of microencapsulation process is useful to properly design of microcapsule with specific characteristics. The aim of this research is to study the mechanism of Urea-Formaldehyde (UF) microcapsules formation. Approach: Microcapsule was prepared in two steps. The first step was the preparation of oil in water emulsion, which was carried out by mixing of UF pre-poly...

  15. Can audio coached 4D CT emulate free breathing during the treatment course?

    DEFF Research Database (Denmark)

    Persson, Gitte F; Nygaard, Ditte E; Olsen, Mikael;

    2008-01-01

    breathing without changing the breathing amplitude. The interfraction variation of the breathing cycle amplitude in free and coached breathing was studied as well as the possible impact of fatigue on longer coaching sessions. METHODS: Thirteen volunteers completed respiratory audio coaching on 3 days within...... during an uncoached versus coached planning 4DCT, respectively, and compared the mean breathing cycle amplitude to the free versus coached breathing from day 2 and 3 simulating free versus coached breathing during treatment. RESULTS: For most volunteers it was impossible to apply coaching without changes...

  16. Synthesis and characterization of alternating poly(amide urea)s and poly(amide urethane urethane)s from ε-caprolactam, diamines, and diphenyl carbonate or ethylene carbonate

    NARCIS (Netherlands)

    Ubaghs, Luc; Sharma, Bhaskar; Keul, Helmut; Höcker, Hartwig; Loontjens, Ton; Benthem, Rolf van

    2003-01-01

    Alternating poly(amide urea)s from ε-caprolactam, diamines H2N-(CH2)x-NH2 (x = 2 - 4), and diphenyl carbonate were prepared in two steps. The microstructure of the poly(amide urea)s, as determined by means of 1H NMR spectroscopy, reveals a strictly alternating sequence of the building blocks. The mo

  17. Electronic Nose Functionality for Breath Gas Analysis during Parabolic Flight

    Science.gov (United States)

    Dolch, Michael E.; Hummel, Thomas; Fetter, Viktor; Helwig, Andreas; Lenic, Joachim; Moukhamedieva, Lana; Tsarkow, Dimitrij; Chouker, Alexander; Schelling, Gustav

    2017-02-01

    The presence of humans in space represents a constant threat for their health and safety. Environmental factors such as living in a closed confinement, as well as exposure to microgravity and radiation, are associated with significant changes in bone metabolism, muscular atrophy, and altered immune response, which has impacts on human performance and possibly results in severe illness. Thus, maintaining and monitoring of crew health status has the highest priority to ensure whole mission success. With manned deep space missions to moon or mars appearing at the horizon where short-term repatriation back to earth is impossible the availability of appropriate diagnostic platforms for crew health status is urgently needed. In response to this need, the present experiment evaluated the functionality and practicability of a metal oxide based sensor system (eNose) together with a newly developed breath gas collecting device under the condition of altering acceleration. Parabolic flights were performed with an Airbus A300 ZeroG at Bordeaux, France. Ambient air and exhaled breath of five healthy volunteers was analyzed during steady state flight and parabolic flight maneuvres. All volunteers completed the study, the breath gas collecting device valves worked appropriately, and breathing through the collecting device was easy and did not induce discomfort. During breath gas measurements, significant changes in metal oxide sensors, mainly sensitive to aromatic and sulphur containing compounds, were observed with alternating conditions of acceleration. Similarly, metal oxide sensors showed significant changes in all sensors during ambient air measurements. The eNose as well as the newly developed breath gas collecting device, showed appropriate functionality and practicability during alternating conditions of acceleration which is a prerequisite for the intended use of the eNose aboard the International Space Station (ISS) for breath gas analysis and crew health status

  18. High and Low Affinity Urea Root Uptake: Involvement of NIP5;1.

    Science.gov (United States)

    Yang, Huayiu; Menz, Jochen; Häussermann, Iris; Benz, Martin; Fujiwara, Toru; Ludewig, Uwe

    2015-08-01

    Urea is the most widespread nitrogen (N) fertilizer worldwide and is rapidly degraded in soil to ammonium by urease. Ammonium is either taken up by plant roots or is further processed to nitrate by soil microorganisms. However, urea can be taken up by roots and is further degraded to ammonium by plant urease for assimilation. When urea is supplied under sterile conditions, it acts as a poor N source for seedlings or adult Arabidopsis thaliana plants. Here, the gene expression of young seedlings exposed to urea and ammonium nitrate nutrition was compared. Several primary metabolism and transport genes, including those for nitrate and urea, were differentially expressed in seedlings. However, urease and most major intrinsic proteins were not differentially expressed, with the exception of NIP6;1, a urea-permeable channel, which was repressed. Furthermore, little overlap with the gene expression with ammonium as the sole N source was observed, confirming that pure urea nutrition is not associated with the ammonium toxicity syndrome in seedlings. The direct root uptake of urea was increased under boron deficiency, in both the high and low affinity range. This activity was entirely mediated by the NIP5;1 channel, which was confirmed to transport urea when expressed in oocytes. The uptake of urea in the high and low affinity range was also determined for maize and wheat roots. The urea uptake by maize roots was only about half that of wheat, but was not stimulated by boron deficiency or N deficiency in either species. This analysis identifies novel components of the urea uptake systems in plants, which may become agronomically relevant to urea uptake and utilization, as stabilized urea fertilizers become increasingly popular.

  19. Effect of urea on degradation of terbuthylazine in soil.

    Science.gov (United States)

    Caracciolo, Anna Barra; Giuliano, Giuseppe; Grenni, Paola; Cremisini, Carlo; Ciccoli, Roberto; Ubaldi, Carla

    2005-05-01

    Pesticide and nitrate contamination of soil and groundwater from agriculture is an environmental and public health concern worldwide. The herbicide terbuthylazine (CBET) has replaced atrazine in Italy and in many other countries because the use of the latter has been banned because of its adverse environmental impacts. Unlike atrazine, knowledge about the fate of CBET in soil is still not extensive, especially regarding its transformation products, but recent monitoring data show its occurrence and that of its main metabolite, desethyl-terbuthylazine (CBAT), in groundwater above the limit of 0.1 microg/L established by European Union Directive and Italian legislation. The objective of this work was to investigate if the presence of the fertilizer urea affects CBET degradation in the soil. Laboratory CBET degradation experiments in the presence/absence of urea were performed with microbiologically active soil and sterilized soil. Terbuthylazine degradation rates under the different experimental conditions were assessed, and the formation, degradation, and transformation of the metabolite CBAT were also studied. Terbuthylazine degradation was affected by the presence of urea, in terms both of a higher disappearance time of 50% of the initial concentration and of a lower amount of CBAT formed. These findings have practical implications for the real-life assessment of the environmental fate of triazine herbicides in agricultural areas since these herbicides are frequently applied to soils receiving ureic fertilizers.

  20. Differential stability of the bovine prion protein upon urea unfolding

    Science.gov (United States)

    Julien, Olivier; Chatterjee, Subhrangsu; Thiessen, Angela; Graether, Steffen P; Sykes, Brian D

    2009-01-01

    Prion diseases, or transmissible spongiform encephalopathies, are a group of infectious neurological diseases associated with the structural conversion of an endogenous protein (PrP) in the central nervous system. There are two major forms of this protein: the native and noninfectious cellular form, PrPC; and the misfolded, infectious, and proteinase K-resistant form, PrPSc. The C-terminal domain of PrPC is mainly α-helical in structure, whereas PrPSc in known to aggregate into an assembly of β-sheets, forming amyloid fibrils. To identify the regions of PrPC potentially involved in the initial steps of the conversion to the infectious conformation, we have used high-resolution NMR spectroscopy to characterize the stability and structure of bovine recombinant PrPC (residues 121 to 230) during unfolding with the denaturant urea. Analysis of the 800 MHz 1H NMR spectra reveals region-specific information about the structural changes occurring upon unfolding. Our data suggest that the dissociation of the native β-sheet of PrPC is a primary step in the urea-induced unfolding process, while strong hydrophobic interactions between helices α1 and α3, and between α2 and α3, stabilize these regions even at very high concentrations of urea. PMID:19693935

  1. Synthesis of dimethyl carbonate from urea and methanol

    Energy Technology Data Exchange (ETDEWEB)

    Polyakov, M.; Kalevaru, V.N.; Martin, A. [Rostock Univ. (Germany). Leibniz Institute for Catalysis; Mueller, K.; Arlt, W. [Erlangen-Nuernberg Univ. (Germany); Strautmann, J.; Kruse, D. [Evonik Industries AG, Marl (Germany). Creavis Technologies and Innovation

    2012-07-01

    Alcoholation of urea with methanol to produce dimethyl carbonate (DMC) is an interesting approach from both the ecological and economical points of view because the urea synthesis usually occurs by the direct use of carbon dioxide. Literature survey reveals that metal oxide catalysts for instance MgO, ZnO, etc. or polyphosphoric acids are mostly used as catalysts for this reaction. In this contribution, we describe the application of ZnO, MgO, CaO, TiO{sub 2}, ZrO{sub 2} or Al{sub 2}O{sub 3} catalysts for the above mentioned reaction. The catalytic activity of different metal oxides towards DMC synthesis was checked and additionally a comparison of achieved conversions with that of predictions made by thermodynamic calculations was also carried out. The achieved conversions are in good agreement with those of calculated ones. The test results reveal that the reaction pressure and temperature have a strong influence on the formation of DMC. Higher reaction pressure improved the yield of DMC. Among different catalysts investigated, ZnO displayed the best performance. The conversion of urea in most cases is close to 100 % and methyl carbamate MC is the major product of the reaction. A part of MC is subsequently converted to DMC, which however depends upon the reaction conditions applied and nature of catalyst used. From the best case, a DMC yield of ca. 8 % could be successfully achieved over ZnO catalyst. (orig.)

  2. Amperometric urea biosensors based on sulfonated graphene/polyaniline nanocomposite

    Directory of Open Access Journals (Sweden)

    Das G

    2015-08-01

    Full Text Available Gautam Das, Hyon Hee Yoon Department of Chemical and Biological Engineering, Gachon University, Seongnam, Gyeonggi-do, South Korea Abstract: An electrochemical biosensor based on sulfonated graphene/polyaniline nanocomposite was developed for urea analysis. Oxidative polymerization of aniline in the presence of sulfonated graphene oxide was carried out by electrochemical methods in an aqueous environment. The structural properties of the nanocomposite were characterized by Fourier-transform infrared, Raman spectroscopy, X-ray photoelectron spectroscopy, and scanning electron microscopy techniques. The urease enzyme-immobilized sulfonated graphene/polyaniline nanocomposite film showed impressive performance in the electroanalytical detection of urea with a detection limit of 0.050 mM and a sensitivity of 0.85 µA·cm-2·mM-1. The biosensor achieved a broad linear range of detection (0.12–12.3 mM with a notable response time of approximately 5 seconds. Moreover, the fabricated biosensor retained 81% of its initial activity (based on sensitivity after 15 days of storage at 4°C. The ease of fabrication coupled with the low cost and good electrochemical performance of this system holds potential for the development of solid-state biosensors for urea detection. Keywords: electrochemical deposition, sulfonated graphene oxide, urease

  3. Antibacterial kaolinite/urea/chlorhexidine nanocomposites: Experiment and molecular modelling

    Energy Technology Data Exchange (ETDEWEB)

    Holešová, Sylva, E-mail: sylva.holesova@vsb.cz [Nanotechnology Centre, VŠB – Technical University of Ostrava, 17.listopadu 15/2172, CZ-708 33 Ostrava, Poruba (Czech Republic); IT4Innovations Centre of Excellence, VŠB – Technical University of Ostrava, 17.listopadu 15/2172, CZ-708 33 Ostrava, Poruba (Czech Republic); Valášková, Marta; Hlaváč, Dominik [Nanotechnology Centre, VŠB – Technical University of Ostrava, 17.listopadu 15/2172, CZ-708 33 Ostrava, Poruba (Czech Republic); IT4Innovations Centre of Excellence, VŠB – Technical University of Ostrava, 17.listopadu 15/2172, CZ-708 33 Ostrava, Poruba (Czech Republic); Madejová, Jana [Institute of Inorganic Chemistry, SAS, Dúbravská cesta 9, SK-845 36 Bratislava (Slovakia); Samlíková, Magda; Tokarský, Jonáš [Nanotechnology Centre, VŠB – Technical University of Ostrava, 17.listopadu 15/2172, CZ-708 33 Ostrava, Poruba (Czech Republic); IT4Innovations Centre of Excellence, VŠB – Technical University of Ostrava, 17.listopadu 15/2172, CZ-708 33 Ostrava, Poruba (Czech Republic); Pazdziora, Erich [Institute of Public Health Ostrava, Centre of Clinical Laboratories, Partyzánské náměstí 7, CZ-702 00 Ostrava (Czech Republic)

    2014-06-01

    Clay minerals are commonly used materials in pharmaceutical production both as inorganic carriers or active agents. The purpose of this study is the preparation and characterization of clay/antibacterial drug hybrids which can be further included in drug delivery systems for treatment oral infections. Novel nanocomposites with antibacterial properties were successfully prepared by ion exchange reaction from two types of kaolinite/urea intercalates and chlorhexidine diacetate. Intercalation compounds of kaolinite were prepared by reaction with solid urea in the absence of solvents (dry method) as well as with urea aqueous solution (wet method). The antibacterial activity of two prepared samples against Enterococcus faecalis, Staphylococcus aureus, Escherichia coli and Pseudomonas aeruginosa was evaluated by finding the minimum inhibitory concentration (MIC). Antibacterial studies of both samples showed the lowest MIC values (0.01%, w/v) after 1 day against E. faecalis, E. coli and S. aureus. A slightly worse antibacterial activity was observed against P. aeruginosa (MIC 0.12%, w/v) after 1 day. Since samples showed very good antibacterial activity, especially after 1 day of action, this means that these samples can be used as long-acting antibacterial materials. Prepared samples were characterized by X-ray diffraction (XRD) and Fourier transform infrared spectroscopy (FTIR). The experimental data are supported by results of molecular modelling.

  4. Urochloa ruziziensis responses to sources and doses of urea

    Directory of Open Access Journals (Sweden)

    João E. S. Lima

    2016-05-01

    Full Text Available ABSTRACT The use of products that promote reduction of nitrogen (N losses from the urea fertilizer can contribute to increasing its use efficiency in forage grasses. This study aimed to evaluate the effects of N sources and doses on the growth of Urochloa ruziziensis. The experiment was carried out in the growing season of 2007/2008 in Santo Antônio de Goiás-GO, in a Brazilian Oxisol. A completely randomized block was used, with four replicates in a factorial scheme, corresponding to two N sources (conventional urea and urea with urease inhibitor and five N doses (0, 50, 100, 200 and 300 kg ha-1, divided into equal applications in five periods (Nov 14 to Dec 13, Dec 14 to Jan 12, Jan 13 to Feb 11 - rainy season, Mar 24 to Apr 22 and Jul 10 to Aug 08 - dry season. The effects of the treatments were evaluated for: shoot dry matter, tiller density, total N content in the leaves and relative chlorophyll content. N fertilizer sources did not affect the evaluated variables; however, N fertilization allowed linear increases in all variables with higher values during the rainy period. The relative chlorophyll content in U. ruziziensis had positive correlation with its dry matter productivity.

  5. Amperometric urea biosensors based on sulfonated graphene/polyaniline nanocomposite.

    Science.gov (United States)

    Das, Gautam; Yoon, Hyon Hee

    2015-01-01

    An electrochemical biosensor based on sulfonated graphene/polyaniline nanocomposite was developed for urea analysis. Oxidative polymerization of aniline in the presence of sulfonated graphene oxide was carried out by electrochemical methods in an aqueous environment. The structural properties of the nanocomposite were characterized by Fourier-transform infrared, Raman spectroscopy, X-ray photoelectron spectroscopy, and scanning electron microscopy techniques. The urease enzyme-immobilized sulfonated graphene/polyaniline nanocomposite film showed impressive performance in the electroanalytical detection of urea with a detection limit of 0.050 mM and a sensitivity of 0.85 (μA · cm(-2)·mM(-1). The biosensor achieved a broad linear range of detection (0.12-12.3 mM) with a notable response time of approximately 5 seconds. Moreover, the fabricated biosensor retained 81% of its initial activity (based on sensitivity) after 15 days of storage at 4°C. The ease of fabrication coupled with the low cost and good electrochemical performance of this system holds potential for the development of solid-state biosensors for urea detection.

  6. Improvement of Egyptian vacuum distillates by urea dewaxing

    Directory of Open Access Journals (Sweden)

    Ehssan M.R. Nassef

    2015-09-01

    Full Text Available The dewaxing of paraffinic lube stocks is an essential step in the production of lubricants to improve the operability of machines especially in winter. The present work deals with study of the urea dewaxing process of two types of Egyptian vacuum distillates. The effect of different compositions of methanol to water saturated with urea and yield of the oil, percent of wax, pour point, refractive index, viscosity, viscosity index and specific gravity of the oil produced from the two types of distillates (I and II were evaluated. The operating conditions of the urea adduct formation with n-paraffins using methanol to water mixture achieved the best pour point at −3.88 °C from an initial temperature of 4.4 °C for distillate I at (25/75 methanol to water. At the same ratio of methanol to water the best specific gravity of oil produced changed from 0.865 to 0.867, with viscosity index of 80. Percent yield of 50% for oil and percent wax of 50% were obtained. Results for distillate II, of higher specific gravity, are comparatively higher than those for distillate I. Experiments were carried out at room temperature.

  7. Influence of papain urea copper chlorophyllin on wound matrix remodeling.

    Science.gov (United States)

    Telgenhoff, Dale; Lam, Kan; Ramsay, Sarah; Vasquez, Valerie; Villareal, Kristine; Slusarewicz, Paul; Attar, Paul; Shroot, Braham

    2007-01-01

    The purpose of this study was to examine the dermal and epidermal alterations associated with wound healing in wounds treated with papain urea copper chlorophyllin (PUC), papain-urea, copper chlorophyllin, or urea base ointment and compare these with moist wound care using a porcine full-thickness infected wound model. All the wounds were evaluated postsurgery for erythema, transepidermal water loss, microscopic morphology, and changes in protein expression. Examination of stained paraffin sections revealed an increase in the number of keratinocytes present in the epidermis of the PUC and papain-treated pigs, relative to moist control. This increase in keratinocyte number corresponded to an increase in the movement of the keratinocytes into the underlying dermis in the form of rete pegs. In the dermis, there appeared to be an increase in blood vessel formation, collagen I deposition, and mature collagen in the papain and PUC treated tissues. The quality of healing appears to be enhanced based on the number of keratinocytes present in the epidermis, the extensive rete peg formation, the increase in vasculature, and the increase in collagen birefringence.

  8. Amperometric urea biosensors based on sulfonated graphene/polyaniline nanocomposite

    Science.gov (United States)

    Das, Gautam; Yoon, Hyon Hee

    2015-01-01

    An electrochemical biosensor based on sulfonated graphene/polyaniline nanocomposite was developed for urea analysis. Oxidative polymerization of aniline in the presence of sulfonated graphene oxide was carried out by electrochemical methods in an aqueous environment. The structural properties of the nanocomposite were characterized by Fourier-transform infrared, Raman spectroscopy, X-ray photoelectron spectroscopy, and scanning electron microscopy techniques. The urease enzyme-immobilized sulfonated graphene/polyaniline nanocomposite film showed impressive performance in the electroanalytical detection of urea with a detection limit of 0.050 mM and a sensitivity of 0.85 (μA · cm−2·mM−1. The biosensor achieved a broad linear range of detection (0.12–12.3 mM) with a notable response time of approximately 5 seconds. Moreover, the fabricated biosensor retained 81% of its initial activity (based on sensitivity) after 15 days of storage at 4°C. The ease of fabrication coupled with the low cost and good electrochemical performance of this system holds potential for the development of solid-state biosensors for urea detection. PMID:26346240

  9. Remote monitoring of breathing dynamics using infrared thermography

    Science.gov (United States)

    Pereira, Carina Barbosa; Yu, Xinchi; Czaplik, Michael; Rossaint, Rolf; Blazek, Vladimir; Leonhardt, Steffen

    2015-01-01

    An atypical or irregular respiratory frequency is considered to be one of the earliest markers of physiological distress. In addition, monitoring of this vital parameter plays a major role in diagnosis of respiratory disorders, as well as in early detection of sudden infant death syndrome. Nevertheless, the current measurement modalities require attachment of sensors to the patient’s body, leading to discomfort and stress. The current paper presents a new robust algorithm to remotely monitor breathing rate (BR) by using thermal imaging. This approach permits to detect and to track the region of interest (nose) as well as to estimate BR. In order to study the performance of the algorithm, and its robustness against motion and breathing disorders, three different thermal recordings of 11 healthy volunteers were acquired (sequence 1: normal breathing; sequence 2: normal breathing plus arbitrary head movements; and sequence 3: sequence of specific breathing patterns). Thoracic effort (piezoplethysmography) served as “gold standard” for validation of our results. An excellent agreement between estimated BR and ground truth was achieved. Whereas the mean correlation for sequence 1–3 were 0.968, 0.940 and 0.974, the mean absolute BR errors reached 0.33, 0.55 and 0.96 bpm (breaths per minute), respectively. In brief, this work demonstrates that infrared thermography is a promising, clinically relevant alternative for the currently available measuring modalities due to its performance and diverse remarkable advantages. PMID:26601003

  10. A Systematic Approach to Multiple Breath Nitrogen Washout Test Quality

    Science.gov (United States)

    Klingel, Michelle; Pizarro, Maria Ester; Hall, Graham L.; Ramsey, Kathryn; Foong, Rachel; Saunders, Clare; Robinson, Paul D.; Webster, Hailey; Hardaker, Kate; Kane, Mica; Ratjen, Felix

    2016-01-01

    Background Accurate estimates of multiple breath washout (MBW) outcomes require correct operation of the device, appropriate distraction of the subject to ensure they breathe in a manner representative of their relaxed tidal breathing pattern, and appropriate interpretation of the acquired data. Based on available recommendations for an acceptable MBW test, we aimed to develop a protocol to systematically evaluate MBW measurements based on these criteria. Methods 50 MBW test occasions were systematically reviewed for technical elements and whether the breathing pattern was representative of relaxed tidal breathing by an experienced MBW operator. The impact of qualitative and quantitative criteria on inter-observer agreement was assessed across eight MBW operators (n = 20 test occasions, compared using a Kappa statistic). Results Using qualitative criteria, 46/168 trials were rejected: 16.6% were technically unacceptable and 10.7% were excluded due to inappropriate breathing pattern. Reviewer agreement was good using qualitative criteria and further improved with quantitative criteria from (κ = 0.53–0.83%) to (κ 0.73–0.97%), but at the cost of exclusion of further test occasions in this retrospective data analysis. Conclusions The application of the systematic review improved inter-observer agreement but did not affect reported MBW outcomes. PMID:27304432

  11. Diaphragmatic Breathing Reduces Exercise-Induced Oxidative Stress

    Directory of Open Access Journals (Sweden)

    Daniele Martarelli

    2011-01-01

    Full Text Available Diaphragmatic breathing is relaxing and therapeutic, reduces stress, and is a fundamental procedure of Pranayama Yoga, Zen, transcendental meditation and other meditation practices. Analysis of oxidative stress levels in people who meditate indicated that meditation correlates with lower oxidative stress levels, lower cortisol levels and higher melatonin levels. It is known that cortisol inhibits enzymes responsible for the antioxidant activity of cells and that melatonin is a strong antioxidant; therefore, in this study, we investigated the effects of diaphragmatic breathing on exercise-induced oxidative stress and the putative role of cortisol and melatonin hormones in this stress pathway. We monitored 16 athletes during an exhaustive training session. After the exercise, athletes were divided in two equivalent groups of eight subjects. Subjects of the studied group spent 1 h relaxing performing diaphragmatic breathing and concentrating on their breath in a quiet place. The other eight subjects, representing the control group, spent the same time sitting in an equivalent quite place. Results demonstrate that relaxation induced by diaphragmatic breathing increases the antioxidant defense status in athletes after exhaustive exercise. These effects correlate with the concomitant decrease in cortisol and the increase in melatonin. The consequence is a lower level of oxidative stress, which suggests that an appropriate diaphragmatic breathing could protect athletes from long-term adverse effects of free radicals.

  12. A Systematic Approach to Multiple Breath Nitrogen Washout Test Quality.

    Directory of Open Access Journals (Sweden)

    Renee Jensen

    Full Text Available Accurate estimates of multiple breath washout (MBW outcomes require correct operation of the device, appropriate distraction of the subject to ensure they breathe in a manner representative of their relaxed tidal breathing pattern, and appropriate interpretation of the acquired data. Based on available recommendations for an acceptable MBW test, we aimed to develop a protocol to systematically evaluate MBW measurements based on these criteria.50 MBW test occasions were systematically reviewed for technical elements and whether the breathing pattern was representative of relaxed tidal breathing by an experienced MBW operator. The impact of qualitative and quantitative criteria on inter-observer agreement was assessed across eight MBW operators (n = 20 test occasions, compared using a Kappa statistic.Using qualitative criteria, 46/168 trials were rejected: 16.6% were technically unacceptable and 10.7% were excluded due to inappropriate breathing pattern. Reviewer agreement was good using qualitative criteria and further improved with quantitative criteria from (κ = 0.53-0.83% to (κ 0.73-0.97%, but at the cost of exclusion of further test occasions in this retrospective data analysis.The application of the systematic review improved inter-observer agreement but did not affect reported MBW outcomes.

  13. Variability of exhaled breath condensate (EBC) volume and pH using a feedback regulated breathing pattern

    Science.gov (United States)

    Exhaled breath condensate (EBC) is a valuable biological medium for non-invasively measuring biomarkers with the potential to reflect organ systems responses to environmental and dietary exposures and disease processes. Collection of EBC has typically been with spontaneous breat...

  14. Urea coated with oxidized charcoal reduces ammonia volatilization

    Directory of Open Access Journals (Sweden)

    Diogo Mendes de Paiva

    2012-08-01

    Full Text Available Urea is the most consumed nitrogen fertilizer in the world. However, its agronomic and economic efficiency is reduced by the volatilization of NH3, which can reach 78 % of the applied nitrogen. The coating of urea granules with acidic compounds obtained by charcoal oxidation has the potential to reduce the volatilization, due to the acidic character, the high buffering capacity and CEC. This work aimed to evaluate the effect of HNO3-oxidized carbon on the control of NH3 volatilization. These compounds were obtained by oxidation of Eucalyptus grandis charcoal, produced at charring temperatures of 350 and 450 ºC, with 4.5 mol L-1 HNO3. The charcoal was oxidized by solubilization in acidic or alkaline medium, similar to the procedure of soil organic matter fractionation (CHox350 and CHox450. CHox was characterized by C, H, O, N contents and their respective atomic relations, by the ratio E4 (absorbance 465 nm by E6 (absorbance 665 nm, and by active acidity and total acidity (CEC. The inhibitory effect of CHox on the urease activity of Canavalia ensiformis was assessed in vitro. The NH3 volatilization from urea was evaluated with and without coating of oxidized charcoal (U-CHox350 or U-CHox450 in a closed system with continuous air flow. The pH of both CHox was near 2.0, but the total acidity of CHox350 was higher, 72 % of which was attributed to carboxylic groups. The variation in the ionization constants of CHox350 was also greater. The low E4/E6 ratios characterize the high stability of the compounds in CHox. CHox did not inhibit the urease activity in vitro, although the maximum volatilization peak from U-CHox450 and U-CHox350 occurred 24 h after that observed for uncoated urea. The lowest volatilization rate was observed for U-CHox350 as well as a 43 % lower total amount of NH3 volatilized than from uncoated urea.

  15. Effect of dietary nitrogen content and intravenous urea infusion on ruminal and portal-drained visceral extraction of arterial urea in lactating Holstein cows

    DEFF Research Database (Denmark)

    Kristensen, Niels Bastian; Storm, Adam Christian; Larsen, Mogens

    2010-01-01

    Urea extraction across ruminal and portal-drained visceral (PDV) tissues were investigated using 9 rumen-cannulated and multi-catheterized lactating dairy cows adapted to low-N (12.9% crude protein) and high-N (17.1% crude protein) diets in a crossover design. The interaction between adaptation...... to dietary treatments and blood plasma concentrations of urea was studied by dividing samplings into a 2.5-h period without urea infusion followed by a 2.5-h period with primed continuous intravenous infusion of urea (0.493 ± 0.012 mmol/kg of BW per h). Cows were sampled at 66 ± 14 and 68 ± 12 d in milk...... and produced 42 ± 1 and 36 ± 1 kg of milk/d with the high-N and low-N diets, respectively. The arterial blood urea concentration before urea infusion was 1.37 and 4.09 ± 0.18 mmol/L with low-N and high-N, respectively. Dietary treatment did not affect the urea infusion-induced increase in arterial urea...

  16. Sleep-disordered breathing and mortality: a prospective cohort study.

    Directory of Open Access Journals (Sweden)

    Naresh M Punjabi

    2009-08-01

    Full Text Available BACKGROUND: Sleep-disordered breathing is a common condition associated with adverse health outcomes including hypertension and cardiovascular disease. The overall objective of this study was to determine whether sleep-disordered breathing and its sequelae of intermittent hypoxemia and recurrent arousals are associated with mortality in a community sample of adults aged 40 years or older. METHODS AND FINDINGS: We prospectively examined whether sleep-disordered breathing was associated with an increased risk of death from any cause in 6,441 men and women participating in the Sleep Heart Health Study. Sleep-disordered breathing was assessed with the apnea-hypopnea index (AHI based on an in-home polysomnogram. Survival analysis and proportional hazards regression models were used to calculate hazard ratios for mortality after adjusting for age, sex, race, smoking status, body mass index, and prevalent medical conditions. The average follow-up period for the cohort was 8.2 y during which 1,047 participants (587 men and 460 women died. Compared to those without sleep-disordered breathing (AHI: or=30.0 events/h sleep-disordered breathing were 0.93 (95% CI: 0.80-1.08, 1.17 (95% CI: 0.97-1.42, and 1.46 (95% CI: 1.14-1.86, respectively. Stratified analyses by sex and age showed that the increased risk of death associated with severe sleep-disordered breathing was statistically significant in men aged 40-70 y (hazard ratio: 2.09; 95% CI: 1.31-3.33. Measures of sleep-related intermittent hypoxemia, but not sleep fragmentation, were independently associated with all-cause mortality. Coronary artery disease-related mortality associated with sleep-disordered breathing showed a pattern of association similar to all-cause mortality. CONCLUSIONS: Sleep-disordered breathing is associated with all-cause mortality and specifically that due to coronary artery disease, particularly in men aged 40-70 y with severe sleep-disordered breathing. Please see later in the

  17. Radial Breathing Modes in Cosmochemistry and Meteoritics

    Science.gov (United States)

    Wilson, T.L.; Wilson, K.B.

    2009-01-01

    One area of continuing interest in cosmochemistry and meteoritics (C&M) is the identification of the nature of Q-phase, although some researchers in C&M are not reporting relevant portions of Raman spectral data. Q is the unidentified carrier of noble gases in carbonaceous chondrites (CCs). Being carbonaceous, the focus has been on any number of Q-candidates arising from the sp2 hybridization of carbon (C). These all derive from various forms of graphene, a monolayer of C atoms packed into a two-dimensional (2D) hexagonal honeycomb lattice that is the basic building block for graphitic materials of all other dimensions for sp2 allotropes of C. As a basic lattice, 2D graphene can be curled into fullerenes (0D), wrapped into carbon nanotubes or CNTs (1D), and stacked into graphite (3D). These take such additional forms as scroll-like carbon whiskers, carbon fibers, carbon onions, GPCs (graphite polyhedral crystals) [6], and GICs (graphite intercalation compounds). Although all of these have been observed in meteoritics, the issue is which can explain the Q-abundances. In brief, one or more of the 0D-3D sp2 hybridization forms of C is Q. For some Q-candidates, the radial breathing modes (RBMs) are the most important Raman active vibrational modes that exist, and bear a direct relevance to solving this puzzle. Typically in C&M they are ignored when present. Their importance is addressed here as smoking-gun signatures for certain Q-candidates and are very relevant to the ultimate identification of Q.

  18. Enhancing the Urea-N Use Efficiency in Maize (Zea mays Cultivation on Acid Soils using Urea Amended with Zeolite and TSP

    Directory of Open Access Journals (Sweden)

    Osumanu H. Ahmed

    2009-01-01

    Full Text Available Problem Statement: Ammonia loss significantly reduces urea-N use efficiency in crop production. Efforts to reduce ammonia loss are laboratory oriented, as such limited in reflecting actual field conditions. This paper reports the effects of urea amended with triple superphosphate (TSP and zeolite (Clinoptilolite on soil pH, soil nitrate, soil exchangeable ammonium, dry matter production, N uptake, fresh cob production and urea-N uptake efficiency in maize (Zea mays cultivation on an acid soil in actual field conditions. Approach: The treatments evaluated were: (i Normal N, P, K application (74.34 g urea, 27.36 g TSP, 24.12 g KCl (T1, (ii Urea-TSP mixture (74.34 g urea+27.36 g TSP+24.12 g KCl (T2, (iii 74.34 g urea+27.36 g TSP+9.0 g zeolite (T3, (iv 74.34 g urea+27.36 g TSP+13.5 g zeolite (T4 and (v No fertilization (T5. Note, the same amount of 24.12 g KCl was used in T3 and T4 plots. Standard procedures were used to determine the selected chemical properties of zeolite, soil, TSP and urea. The pH of the urea, zeolite, soil and TSP were determined in a 1:2.5 soil: distilled water suspension and/or 0.01 N CaCl2 using a glass electrode. The CEC of the zeolite was determined by the CsCl method. Soil CEC was determined by leaching with 1 N ammonium acetate buffer adjusted to pH 7.0 followed by steam distillation. Soil samples at harvest were analyzed for pH using the method previously outlined. Exchangeable ammonium and nitrate at harvest were extracted from the soil samples by the method of Keeney and Nelson and the amount determined using a LACHAT Autoanalyzer. Total N of the plant tissues (stem and leaf was determined by the Micro-Kjeldhal method. Results: Urea amended with TSP and zeolite treatments and Urea only (urea without additives did not have long term effect on soil pH and accumulation of soil exchangeable ammonium and nitrate. Treatments with higher amounts of TSP and zeolite significantly increased the dry matter (stem and leaf

  19. A study on the indirect urea dosing method in the Selective Catalytic Reduction system

    Science.gov (United States)

    Brzeżański, M.; Sala, R.

    2016-09-01

    This article presents the results of studies on concept solution of dosing urea in a gas phase in a selective catalytic reduction system. The idea of the concept was to heat-up and evaporate the water urea solution before introducing it into the exhaust gas stream. The aim was to enhance the processes of urea converting into ammonia, what is the target reductant for nitrogen oxides treatment. The study was conducted on a medium-duty Euro 5 diesel engine with exhaust line consisting of DOC catalyst, DPF filter and an SCR system with a changeable setup allowing to dose the urea in liquid phase (regular solution) and to dose it in a gas phase (concept solution). The main criteria was to assess the effect of physical state of urea dosed on the NOx conversion ratio in the SCR catalyst. In order to compare both urea dosing methods a special test procedure was developed which consisted of six test steps covering a wide temperature range of exhaust gas generated at steady state engine operation condition. Tests were conducted for different urea dosing quantities defined by the a equivalence ratio. Based on the obtained results, a remarkable improvement in NOx reduction was found for gas urea application in comparison to the standard liquid urea dosing. Measured results indicate a high potential to increase an efficiency of the SCR catalyst by using a gas phase urea and provide the basis for further scientific research on this type of concept.

  20. Analysis of the Stability of Urea in Dried Blood Spots Collected and Stored on Filter Paper

    Science.gov (United States)

    Lakshmy, Ramakrishnan; Mukhopadhyay, Ashok Kumar; Jailkhani, Bansi Lal

    2013-01-01

    The ability to use dry blood spots (DBSs) on filter paper for the analysis of urea levels could be an important diagnostic tool for areas that have limited access to laboratory facilities. We developed a method for the extraction and quantification of urea from DBSs that were stored on 3M Whatman filter paper and investigated the effect of long-term storage on the level of urea in DBSs. DBSs of 4.5 mm in diameter were used for our assay, and we determined the urea levels in blood using a commercially available enzymatic kit (UV GLDH-method; Randox laboratories Ltd., UK). The DBSs on filter discs were stored at 4℃ or at 37℃ for 120 days. The mean intra- and inter-assay coefficient of variance for our method of urea extraction from dried blood was 4.2% and 6.3%, respectively. We collected 75 fresh blood samples and compared the urea content of each fresh sample with the urea content of DBSs taken from corresponding fresh blood samples. Regression analysis reported a regression coefficient (r) value of 0.97 and a recovery of urea from dried spots was 102.2%. Urea concentrations in DBSs were stable for up to 120 and 90 days when stored at 4℃ and 37℃, respectively. Our results show that urea can be stored and quantitatively recovered from small volumes of blood that was collected on filter paper. PMID:23667845

  1. Urea as a Nitrogen Source in a Black Tiger Shrimp (Penaeus monodon Closed Culture System

    Directory of Open Access Journals (Sweden)

    Supannee SUWANPAKDEE

    2010-06-01

    Full Text Available Urea [(NH22CO] is an organic compound that serves an important role in the metabolism of nitrogen-containing compound by animals. Urea is widely used in aquaculture systems. This study investigated the effects of urea on growth of Penaeus monodon. Shrimp were reared in 500 l fiber tanks. There was no exchange of water throughout the experiment. Shrimp with an average body weight of 10.99 ± 0.19 g were stocked at a density of 32 shrimp/m2 in 20 ppt diluted seawater and fed with 38 % protein diet for 9 weeks. Urea was added into the culture tanks at a concentration of 1.25 ppm once a week. The results show that urea slightly affects growth and survival of shrimp. Shrimp reared in the culture pond with added urea had a marginal better growth rate (p > 0.05 while the survival rate was significantly higher than the control group (p < 0.05. The urea in the closed culture tanks was shown to reduce the toxicity of ammonia in soil and promoted growth of plankton communities. Adding urea has no effect on water quality. This study concluded that urea is a potential nitrogen source in closed culture systems when the nitrogen input through the feeding regime is limited. It suggests that urea should be added at a concentration of 1.25 ppm once a week into culture systems with limiting nitrogen sources.

  2. Synergistic behavior of glycine betaine-urea mixture: A molecular dynamics study

    Science.gov (United States)

    Kumar, Narendra; Kishore, Nand

    2013-09-01

    Glycine betaine (GB) is one of the most important osmolyte which is known to stabilize proteins as well as counteract the denaturing effect of urea. There have been many studies indicating protein stabilization and counteraction of the effect of urea by GB. However, the exact mechanism of counteraction is still debated and is of important research interest. In this study, distribution functions, hydrogen bonds, and energetics were analysed to understand different interactions between GB and urea, and their solvation properties in presence of each other. The results show that in the GB-urea mixture, GB acted as a stronger osmolyte and urea became a weaker denaturing agent than its individual counterparts. The increase in the solvation of urea and GB in GB-urea mixture and their mutual interactions through hydrogen bonding and coulombic energy resulted in more involvement of GB and urea with solvent as well as with themselves. This might result in the increase of the exclusion of GB from protein surface and decrease in the protein-urea interactions in the mixture. This synergistic behavior might be the prime reason for the counteraction of denaturing effect of urea by GB.

  3. Effect of nickel nutrition on yield, urea accumulation and urease enzyme activity of lettuce

    Directory of Open Access Journals (Sweden)

    M. Afyuni

    2011-04-01

    Full Text Available Although nickel (Ni is known as an essential element for higher plants, the biological effects of this nutrient on growth, yield, and N metabolism of some plants, particularly leafy vegetables, is still unknown. Therefore, this study was carried out to investigate the effects of Ni and urea nutrition on the growth and yield of lettuce (Lactuca sativa L. cv. Baker and urea accumulation in plant tissues. In this study, nitrogen was supplied from the source of urea or ammonium nitrate at three levels (5, 10 and 20 mM and Ni was supplied in the form of NiCl2 at two levels (0 and 0.04 µM. The plants were harvested 6 weeks after transplanting and the fresh weight of shoots and roots were determined. The shoots urea concentration and activity of urease enzyme in the leaves were also measured. The results indicated that shoots fresh weight of the urea-fed plants increased with increasing urea concentration in the nutrient solution. Addition of Ni to the nutrient solution significantly promoted the root and shoots fresh weight of urea-fed plants, regardless of N level. Ni nutrition significantly increased the urease activity in the lettuce leaves and as a result, reduced urea accumulation in the shoots and toxicity effects of urea. Therefore, it seems that urea in combination with Ni can successfully be used in production of lettuce in soilless culture systems.

  4. ENSURING THE AVAILABILITY AND RELIABILITY OF UREA DOSING FOR ON-ROAD AND NON-ROAD

    Energy Technology Data Exchange (ETDEWEB)

    Barton, G; Lonsdale, B

    2003-08-24

    The purpose of this presentation is to address two important issues. The first issue is nationwide availability of urea. The second is assurance by the engine maker that the engine cannot operate without urea. In regard to the first issue, North American urea production can support SCR needs for the Heavy Duty truck industry. The existing distribution methods, pathways and technology could be utilized for urea supply with no new invention required. Urea usage and storage capacity on vehicles would support long distances between tank refills, as SCR could be initially rolled out with a limited infrastructure. The price of urea should be less than diesel fuel and urea SCR should have a fuel economy advantage over competing technologies. It can be in place by 2007. In regard to the second issue, sensor technology exists to monitor urea tank level and verify that the fluid in the tank is urea. NOx sensors are available to monitor tailpipe NOx, ensuring the entire SCR system is functioning properly, and inferring that urea is in the system. The monitoring system could be used to monitor compliance, record faults, and initiate enforcement actions as necessary. The monitoring system could initiate actions to encourage compliance.

  5. Fast-starting after a breath: air-breathing motions are kinematically similar to escape responses in the catfish Hoplosternum littorale

    DEFF Research Database (Denmark)

    Domenici, Paolo; Norin, Tommy; Bushnell, Peter G.;

    2015-01-01

    that air-breathing fish may use C-starts in the context of gulping air at the surface. Hoplosternum littorale is an air-breathing freshwater catfish found in South America. Field video observations reveal that their air-breathing behaviour consists of air-gulping at the surface, followed by a fast turn...

  6. Fate of Urea Nitrogen Applied to Rape Grown on a Red Soil and Efficiency of Urea in Raising Rape Yield

    Institute of Scientific and Technical Information of China (English)

    CAIGUI-XIN; WUYI-WEI; 等

    1995-01-01

    Fate of urea nitrogen(N) applied to rape grown on a red soil was investigated by the 15N mass balance technique.and efficiency of urea and effect of nutrients balance in raising rape yield were investigated in a field plot experiment.One hundred and thirty -eight kg N/ha,86kg N/ha as basal dressing and 52 kg N/ha as top dressing,was applied with band application technique.The experiment was conducted in the southeast of china ,near Yingtan City,Jianxi Province.Results from 15N mass balance study showed that when urea urea was applied as basal dressing the plant recovery was 44.0% of the applied N for Treatment T (with application of N,P,K,B and lime),Plant recoveries were 38.0%-40.5% for Treatments-K,-B-lime and+RS(without application of K,B or lime as well as with additional rice straw compared with Teatment T),which were not significantly different from Treatment T.In contrast ,plant recovery was only 5.1% for Treatment-P(without application of P), indicating that P was the factor limiting N uptake by rape.However,N remaining in 0-0.30 m soil was high up to 71.6% for Treatment-P,while the corresponding data were 33.0%-42.6% for the other treatments.The total recovery of applied N(including plant recovery and N remaining in 0-0.60 m soil) was 91.5% for Treatment T when urea was applied as basal dressing,while almost all the applied N was recovered when ureawas applied as top drssing,It was suggested that N loss was greatly controlled by using band application method in this experiment.Results from the field plot experiment field plot experiment showed that N supply capacity of this red soil was very low,and the efficiency of the applied N was quite high,7.1kg rape seed was increased by application of one kg N for Treatment T.Nitrogen and phosphorus were the key factors limiting rape yield,and the yield was very low when neither of them was applied.The yield in Treatment-K was significantly lower than that in Treatment T,With the former accounting for 77% of the

  7. Salivary concentrations of urea released from a chewing gum containing urea and how these affect the urea content of gel-stabilized plaques and their pH after exposure to sucrose.

    Science.gov (United States)

    Dawes, C; Dibdin, G H

    2001-01-01

    The objectives were to: (1) determine the salivary concentrations of urea during 20 min chewing of a sugar-free gum containing 30 mg of urea; (2) measure the degree to which this urea would diffuse into a gel-stabilized plaque; (3) study the effect of the urea on the fall and subsequent rise in pH (Stephan curve) on exposure to 10% sucrose for 1 min; (4) model the measurements 2 and 3 mathematically. In point 1, the salivary urea concentration of the 12 subjects peaked at 47 mmol/l in the first 2 min of gum chewing, falling within 15 min to the unstimulated salivary concentration of 3.4 mmol/l. Recovery of urea from the saliva averaged 81.5%. 'Plaques' of 1% agarose or 67% dead bacteria in agarose accumulated urea from the saliva roughly as expected, whereas those plaques containing 8% live and 59% dead Streptococcus vestibularis showed negligible accumulation. Computer modelling showed this difference to be due to urease of live bacteria breaking down the urea as rapidly as it entered the plaque. Simulation of the effect of gum chewing subsequent to initiation of a Stephan curve in the latter type of plaque showed a rapid rise in pH but then a fall again on return to unstimulated conditions. This fall had not been seen in previous studies, with Streptococcus oralis, nor was it predicted by the computer modelling. Neither experimental simulation nor computer modelling suggested that chewing urea-containing gum before exposure to sucrose would have any effect on a subsequent Stephan curve. Thus chewing gum is only likely to inhibit caries when it is chewed after consumption of fermentable carbohydrate, rather than before.

  8. Bacterial contamination of anesthesia machines’ internal breathing-circuit-systems

    Science.gov (United States)

    Spertini, Verena; Borsoi, Livia; Berger, Jutta; Blacky, Alexander; Dieb-Elschahawi, Magda; Assadian, Ojan

    2011-01-01

    Background: Bacterial contamination of anesthesia breathing machines and their potential hazard for pulmonary infection and cross-infection among anesthetized patients has been an infection control issue since the 1950s. Disposable equipment and bacterial filters have been introduced to minimize this risk. However, the machines’ internal breathing-circuit-system has been considered to be free of micro-organisms without providing adequate data supporting this view. The aim of the study was to investigate if any micro-organisms can be yielded from used internal machines’ breathing-circuit-system. Based on such results objective reprocessing intervals could be defined. Methods: The internal parts of 40 anesthesia machines’ breathing-circuit-system were investigated. Chi-square test and logistic regression analysis were performed. An on-site process observation of the re-processing sequence was conducted. Results: Bacterial growth was found in 17 of 40 machines (43%). No significant difference was ascertained between the contamination and the processing intervals. The most common contaminants retrieved were coagulase negative Staphylococci, aerobe spore forming bacteria and Micrococcus species. In one breathing-circuit-system, Escherichia coli, and in one further Staphylococcus aureus were yielded. Conclusion: Considering the availability of bacterial filters installed on the outlet of the breathing-circuit-systems, the type of bacteria retrieved and the on-site process observation, we conclude that the contamination found is best explained by a lack of adherence to hygienic measures during and after re-processing of the internal breathing-circuit-system. These results support an extension of the re-processing interval of the anesthesia apparatus longer than the manufacturer’s recommendation of one week. However, the importance of adherence to standard hygienic measures during re-processing needs to be emphasized. PMID:22242095

  9. Increased Prevalence of Sleep-Disordered Breathing in Adults

    Science.gov (United States)

    Peppard, Paul E.; Young, Terry; Barnet, Jodi H.; Palta, Mari; Hagen, Erika W.; Hla, Khin Mae

    2013-01-01

    Sleep-disordered breathing is a common disorder with a range of harmful sequelae. Obesity is a strong causal factor for sleep-disordered breathing, and because of the ongoing obesity epidemic, previous estimates of sleep-disordered breathing prevalence require updating. We estimated the prevalence of sleep-disordered breathing in the United States for the periods of 1988–1994 and 2007–2010 using data from the Wisconsin Sleep Cohort Study, an ongoing community-based study that was established in 1988 with participants randomly selected from an employed population of Wisconsin adults. A total of 1,520 participants who were 30–70 years of age had baseline polysomnography studies to assess the presence of sleep-disordered breathing. Participants were invited for repeat studies at 4-year intervals. The prevalence of sleep-disordered breathing was modeled as a function of age, sex, and body mass index, and estimates were extrapolated to US body mass index distributions estimated using data from the National Health and Nutrition Examination Survey. The current prevalence estimates of moderate to severe sleep-disordered breathing (apnea-hypopnea index, measured as events/hour, ≥15) are 10% (95% confidence interval (CI): 7, 12) among 30–49-year-old men; 17% (95% CI: 15, 21) among 50–70-year-old men; 3% (95% CI: 2, 4) among 30–49-year-old women; and 9% (95% CI: 7, 11) among 50–70 year-old women. These estimated prevalence rates represent substantial increases over the last 2 decades (relative increases of between 14% and 55% depending on the subgroup). PMID:23589584

  10. [Periodic breathing with periodic oxygen variation in infancy].

    Science.gov (United States)

    von Czettritz, G; Bax, R T; Eckardt, T; Springer, S; Emmrich, P

    1996-01-01

    Oxycardiorespirographies, recording arterial oxygen saturation (SaO2), breathing movements, heart rate and ECG with a mean recording time of 22.3 hours, were performed on 85 preterm (mean postconceptional age: 38 weeks) and 81 term infants (mean postconceptional age 42.4 weeks). 83% of the preterm infants showed periodic breathing (PB), in 97% of them this was accompanied by periodic variations of arterial oxygen saturation (PVO). Periodic breathing occurred in 61% of the term infants, 84% of them showed PVO during periodic breathing. The mean variation of oxygen saturation was between 92.8 and 96.8% (+/- 1.7) for preterm and between 92.9 and 96.0% (+/- 2.2) for term infants. In some infants the peak to peak amplitude of the SaO2 cycles was up to 22%, sometimes a further fall of SaO2 occurred. There was a strong correlation of the PVO both at the beginning and end of the episode as well as with the PB-cycle periodicity itself. The fall of the oxygen saturation occurred 3.1 to 7.8 s after the beginning of the first apnea of an episode of periodic breathing, the minimum SaO2 was reached approximately 4.2 to 8.6 s later. This periodic rapid fall of SaO2 from a high oxygenation level cannot be explained by the apneas of a rather short duration during periodic breathing. It is discussed that PVO during periodic breathing may be caused by an ideopathic right to left shunting across fetal circulation pathways which occurs intermittently and periodically. This mechanism could-via patterns of reaction exhibited during the fetal and neonatal time period-lead to acute hypoxemia, as found in apparently life threatening events (ALTE) and as postulated in sudden infant death (SID).

  11. Noninvasive detection of lung cancer by analysis of exhaled breath

    Directory of Open Access Journals (Sweden)

    Denz Hubert

    2009-09-01

    Full Text Available Abstract Background Lung cancer is one of the leading causes of death in Europe and the western world. At present, diagnosis of lung cancer very often happens late in the course of the disease since inexpensive, non-invasive and sufficiently sensitive and specific screening methods are not available. Even though the CT diagnostic methods are good, it must be assured that "screening benefit outweighs risk, across all individuals screened, not only those with lung cancer". An early non-invasive diagnosis of lung cancer would improve prognosis and enlarge treatment options. Analysis of exhaled breath would be an ideal diagnostic method, since it is non-invasive and totally painless. Methods Exhaled breath and inhaled room air samples were analyzed using proton transfer reaction mass spectrometry (PTR-MS and solid phase microextraction with subsequent gas chromatography mass spectrometry (SPME-GCMS. For the PTR-MS measurements, 220 lung cancer patients and 441 healthy volunteers were recruited. For the GCMS measurements, we collected samples from 65 lung cancer patients and 31 healthy volunteers. Lung cancer patients were in different disease stages and under treatment with different regimes. Mixed expiratory and indoor air samples were collected in Tedlar bags, and either analyzed directly by PTR-MS or transferred to glass vials and analyzed by gas chromatography mass spectrometry (GCMS. Only those measurements of compounds were considered, which showed at least a 15% higher concentration in exhaled breath than in indoor air. Compounds related to smoking behavior such as acetonitrile and benzene were not used to differentiate between lung cancer patients and healthy volunteers. Results Isoprene, acetone and methanol are compounds appearing in everybody's exhaled breath. These three main compounds of exhaled breath show slightly lower concentrations in lung cancer patients as compared to healthy volunteers (p Conclusion GCMS-SPME is a relatively

  12. Effect of urea addition on giant reed ensilage and subsequent methane production by anaerobic digestion.

    Science.gov (United States)

    Liu, Shan; Ge, Xumeng; Liew, Lo Niee; Liu, Zhe; Li, Yebo

    2015-09-01

    The effect of urea addition on giant reed ensilage and sequential anaerobic digestion (AD) of the ensiled giant reed was evaluated. The dry matter loss during ensilage (up to 90 days) with or without urea addition was about 1%. Addition of 2% urea enhanced production of lactic acid by about 4 times, and reduced production of propionic acid by 2-8 times. Besides, urea addition reduced degradation of cellulose and hemicellulose, and increased degradation of lignin in giant reed during ensilage. Ensilage with or without urea addition had no significant effects on the enzymatic digestibility of giant reed, but ensilage with urea addition achieved a cumulative methane yield of 173 L/kg VS, which was 18% higher than that of fresh giant reed. The improved methane yield of giant reed could be attributed to the production of organic acids and ethanol during ensilage.

  13. Effect of slow-release urea on soil nematode community structure in a Chinese soybean field

    Institute of Scientific and Technical Information of China (English)

    Xuekun HOU; Ruichang ZHAI

    2009-01-01

    The effect of slow-release urea on soil nematode community structure was investigated in a soybean field in northeast China.Three treatments,no urea (CK),conventional urea (U) and slow-release urea (SRU),were arranged in a completely random design.The results show that the abundance of total nematodes was significantly higher in SRU than in CK and U.Significant differences in the abundance of bacterivores with colonizer-persister (cp) values 2-3,fungivores with cp 2 and herbivores with cp 3 were found among different treatments.Forty-one genera were identified,of which Acrobeloides,Aphelenchus and Heterodera were dominant.Soil nematode guilds and genera exhibited different responses to slow-release urea.The most trophic groups and genera had greater abundances in SRU than in CK and U.Slow-release urea had a positive effect on soil nematode community structure.

  14. An evaluation of twelve nested models of transperitoneal transport of urea

    DEFF Research Database (Denmark)

    Graff, J; Fugleberg, S; Joffe, P;

    1995-01-01

    Models of transperitoneal urea transport are generally based on the one-compartment assumption, i.e. that the plasma water urea concentration in the peritoneal capillary bed is equal to the plasma water urea concentration in the peripheral veins. The aim of this study was to investigate...... the mechanism(s) of transperitoneal urea transport and to test the one-compartment assumption for urea. A total of 12 nested models were formulated and validated on the basis of experimental results obtained from 23 non-diabetic patients undergoing peritoneal dialysis. The validation procedure demonstrated...... that transperitoneal transport of urea probably involves diffusion, non-lymphatic convection and lymphatic convection. It was furthermore demonstrated that the inclusion of lymphatic convection changes the mass transfer area coefficient considerably. Finally, no deviation from the one-compartment assumption...

  15. Regulation of urea synthesis during the acute phase response in rats

    DEFF Research Database (Denmark)

    Thomsen, Karen Louise; Jessen, Niels; Buch Møller, Andreas

    2013-01-01

    of the tumor necrosis factor-α (TNF-α)-induced acute-phase response in rats. We used four methods to study the regulation of urea synthesis: We examined urea cycle enzyme mRNA levels in liver tissue, the hepatocyte urea cycle enzyme proteins, the in vivo capacity of urea-N synthesis (CUNS), and known humoral...... regulators of CUNS at 1, 3, 24, and 72 h after TNF-α injection (25 μg/kg iv rrTNF-α) in rats. Serum acute-phase proteins and their liver mRNA levels were also measured. The urea cycle enzyme mRNA levels acutely decreased and then gradually normalized, whereas the urea cycle enzyme proteins remained...

  16. Kinetic barriers in the isomerization of substituted ureas: implications for computer-aided drug design

    Science.gov (United States)

    Loeffler, Johannes R.; Ehmki, Emanuel S. R.; Fuchs, Julian E.; Liedl, Klaus R.

    2016-05-01

    Urea derivatives are ubiquitously found in many chemical disciplines. N, N'-substituted ureas may show different conformational preferences depending on their substitution pattern. The high energetic barrier for isomerization of the cis and trans state poses additional challenges on computational simulation techniques aiming at a reproduction of the biological properties of urea derivatives. Herein, we investigate energetics of urea conformations and their interconversion using a broad spectrum of methodologies ranging from data mining, via quantum chemistry to molecular dynamics simulation and free energy calculations. We find that the inversion of urea conformations is inherently slow and beyond the time scale of typical simulation protocols. Therefore, extra care needs to be taken by computational chemists to work with appropriate model systems. We find that both knowledge-driven approaches as well as physics-based methods may guide molecular modelers towards accurate starting structures for expensive calculations to ensure that conformations of urea derivatives are modeled as adequately as possible.

  17. Breath analysis: clinical research to the end-user market.

    Science.gov (United States)

    Smith, T

    2011-09-01

    Breath research is now well established and is solving some of the applications in the area of identifying volatiles for medical diagnosis. This paper looks at how this research has been taken to an end-user market. It is not intended to be an indepth study of the science but simply to draw attention to the role of the commercial link between the researcher and end-user. This market is not only in research but exists in hospitals, clinics, sports medicine and even homecare. The link between research and the end-user market is a vital one to avoid breath analysis being the tool of researchers only. The ubiquitous use of breath analysis depends upon it. This is a review of some of the success stories in commercializing the important breath analysis research that has been conducted over the last few decades. In order to make breath analysis the new blood test, products that have end-user appeal need to be developed and routes to market established.

  18. Association between oral habits, mouth breathing and malocclusion.

    Science.gov (United States)

    Grippaudo, C; Paolantonio, E G; Antonini, G; Saulle, R; La Torre, G; Deli, R

    2016-10-01

    The ratio of bad habits, mouth breathing and malocclusion is an important issue in view of prevention and early treatment of disorders of the craniofacial growth. While bad habits can interfere with the position of the teeth and normal pattern of skeletal growth, on the other hand obstruction of the upper airway, resulting in mouth breathing, changes the pattern of craniofacial growth causing malocclusion. Our crosssectional study, carried out on 3017 children using the ROMA index, was developed to verify if there was a significant correlation between bad habits/mouth breathing and malocclusion. The results showed that an increase in the degree of the index increases the prevalence of bad habits and mouth breathing, meaning that these factors are associated with more severe malocclusions. Moreover, we found a significant association of bad habits with increased overjet and openbite, while no association was found with crossbite. Additionally, we found that mouth breathing is closely related to increased overjet, reduced overjet, anterior or posterior crossbite, openbite and displacement of contact points. Therefore, it is necessary to intervene early on these aetiological factors of malocclusion to prevent its development or worsening and, if already developed, correct it by early orthodontic treatment to promote eugnatic skeletal growth.

  19. Data Mining Techniques Applied to Hydrogen Lactose Breath Test

    Science.gov (United States)

    Nepomuceno-Chamorro, Isabel; Pontes-Balanza, Beatriz; Hernández-Mendoza, Yoedusvany; Rodríguez-Herrera, Alfonso

    2017-01-01

    In this work, we present the results of applying data mining techniques to hydrogen breath test data. Disposal of H2 gas is of utmost relevance to maintain efficient microbial fermentation processes. Objectives Analyze a set of data of hydrogen breath tests by use of data mining tools. Identify new patterns of H2 production. Methods Hydrogen breath tests data sets as well as k-means clustering as the data mining technique to a dataset of 2571 patients. Results Six different patterns have been extracted upon analysis of the hydrogen breath test data. We have also shown the relevance of each of the samples taken throughout the test. Conclusions Analysis of the hydrogen breath test data sets using data mining techniques has identified new patterns of hydrogen generation upon lactose absorption. We can see the potential of application of data mining techniques to clinical data sets. These results offer promising data for future research on the relations between gut microbiota produced hydrogen and its link to clinical symptoms. PMID:28125620

  20. Acoustic rhinometry in mouth breathing patients: a systematic review

    Directory of Open Access Journals (Sweden)

    Ana Carolina Cardoso de Melo

    2015-04-01

    Full Text Available INTRODUCTION: When there is a change in the physiological pattern of nasal breathing, mouth breathing may already be present. The diagnosis of mouth breathing is related to nasal patency. One way to access nasal patency is by acoustic rhinometry.OBJECTIVE: To systematically review the effectiveness of acoustic rhinometry for the diagnosis of patients with mouth breathing.METHODS: Electronic databases LILACS, MEDLINE via PubMed and Bireme, SciELO, Web of Science, Scopus, PsycInfo, CINAHL, and Science Direct, from August to December 2013, were consulted. 11,439 articles were found: 30 from LILACS, 54 from MEDLINE via Bireme, 5558 from MEDLINE via PubMed, 11 from SciELO, 2056 from Web of Science, 1734 from Scopus, 13 from PsycInfo, 1108 from CINAHL, and 875 from Science Direct. Of these, two articles were selected.RESULTS: The heterogeneity in the use of equipment and materials for the assessment of respiratory mode in these studies reveals that there is not yet consensus in the assessment and diagnosis of patients with mouth breathing.CONCLUSION: According to the articles, acoustic rhinometry has been used for almost twenty years, but controlled studies attesting to the efficacy of measuring the geometry of nasal cavities for complementary diagnosis of respiratory mode are warranted.

  1. [The influence of breathing mode on the oral cavity].

    Science.gov (United States)

    Surtel, Anna; Klepacz, Robert; Wysokińska-Miszczuk, Joanna

    2015-12-01

    Nose breathing is one of the key factors in the proper development and functioning of the oral cavity. The air passing through the nasal cavity is warmed and humidified while dust and other particulate matter is removed. It is also important as far as bone formation is concerned. The obstruction or congestions of the upper respiratory tract may negatively affect the correct and most optimal (nasal) respiratory tract. The switch from nasal to mouth breathing may lead to serious clinical consequences. Children with the clinical diagnosis of mouth breathing are usually pale, apathetic and they lack concentration and often get tired. Disorders resulting from hypoxy may also be the reason from sleep disturbances, such as frequent waking-up, nocturia, difficulties falling aslee. The main clinical manifestations of mouth breathing appear in the craniofacial structures. Mouth breathers frequently suffer from dental malocclusions and craniofacial bone abnormalities. Chronic muscle tension around the oral cavity could result in the widening of cranio-vertebral angle, posterior position of mandibula and narrow maxillary arch. Among dental alterations the most common are class II malocclusion (total or partial) with the protrusion of the anterior teeth, cross bite (unilateral or bilateral), anterior open bite and primary crowded teeth. Apart from malocclusion, chronic gingivitis, periodontitis, candida infections and halitosis are frequently present in mouth--breathing patients.

  2. Effect of etiology of mouth breathing on craniofacial morphology

    Directory of Open Access Journals (Sweden)

    Mohammadreza Majidi

    2008-07-01

    Full Text Available Introduction: Nasal septal deviation and hypertrophy of the adenoids and palatine tonsils are two common causes of nasopharyngeal obstruction and consequently mouth breathing in children. It is accepted that chronic mouth breathing influences craniofacial growth and development. The aim of this study was to evaluate the differences of craniofacial morphology in children with two different etiological factors of mouth breathing. Materials and Methods: Study design: cross sectional. The research was conducted between 2005-2007 on 47 predominantly mouth breathing patients aged 6-10 years. After otorhinolaryngologic examination, patients were divided into two groups based on the etiology of nasopharyngeal obstruction: group 1, with Adenoid hypertrophy and group 2 with nasal septal deviation. Lateral cephalometric radiographs were obtained to assess craniofacial development. Data gained were statistically evaluated by Mann-Whitney and T-student tests. Results: With respect to the inclination of the mandibular and palatal planes, anteroposterior relationship of maxilla and mandible to the cranial base, and indexes of facial height proportions, no significant differences were observed between two groups of children with mouth breathing. Only the gonial and craniocervical angle measurements were significantly larger in children with adenoid hypertrophy (P

  3. Cheyne-Stokes respiration: hypoxia plus a deep breath that interrupts hypoxic drive, initiating cyclic breathing.

    Science.gov (United States)

    Guntheroth, Warren G

    2011-11-01

    In the 19th Century, Cheyne and Stokes independently reported cycles of respiration in patients with heart failure, beginning with apnea, followed by a few breaths. However Cheyne-Stokes respiration (C-SR) can also occur in healthy individuals with sleep, and was demonstrated in 1908 with voluntary hyperventilation, followed by apnea that Haldane blamed on hypoxia, subsequently called post-hyperventilation apnea. Additional theories explaining C-SR did not appear until 1954, based on control theory, specifically a feed-back regulator controlling CO(2). This certainly describes control of normal respiration, but to produce an unstable state such as C-SR requires either a very long transit time (3½ min) or an increase of the controller gain (13 times), physiologically improbable. There is general agreement that apnea initiates C-SR but that has not been well explained except for post-hyperventilation apnea, and that explanation is not compatible with a study by Nielsen and Smith in 1951. They plotted the effects of diminished oxygen on ventilation (V) in relation to CO(2) (Fig. 1). They found that the slope of V/CO(2) (gain) increased with hypoxia, but it flattened at a moderate CO(2) level and had nointercept with zero (apnea). It is also incompatible with our published findings in 1975 that showed that apnea did not occur until an extreme level of hypoxia occurred (the PO(2) fell below 10 mmHg), followed shortly by gasping. Much milder hypoxia underlies most cases of C-SR, when hypoxic drive replaces the normal CO(2)-based respiratory drive, in a failsafe role. I hypothesize that the cause of apnea is a brief interruption of hypoxic drive caused by a pulse of oxygen from a stronger than average breath, such as a sigh. The rapidity of onset of apnea in response to a pulse of oxygen, reflects the large pressure gradient for oxygen from air to lung with each breath, in contrast to CO(2). With apnea, there is a gradual fall in oxygen, resulting in a resumption of

  4. Functional materials from self-assembled bis-urea macrocycles.

    Science.gov (United States)

    Shimizu, Linda S; Salpage, Sahan R; Korous, Arthur A

    2014-07-15

    CONSPECTUS: This Account highlights the work from our laboratories on bis-urea macrocycles constructed from two C-shaped spacers and two urea groups. These simple molecular units assembled with high fidelity into columnar structures guided by the three-centered urea hydrogen bonding motif and aryl stacking interactions. Individual columns are aligned and closely packed together to afford functional and homogeneous microporous crystals. This approach allows for precise and rational control over the dimensions of the columnar structure simply by changing the small molecular unit. When the macrocyclic unit lacks a cavity, columnar assembly gives strong pillars. Strong pillars with external functional groups such as basic lone pairs can expand like clays to accept guests between the pillars. Macrocycles that contain sizable interior cavities assemble into porous molecular crystals with aligned, well-defined columnar pores that are accessible to gases and guests. Herein, we examine the optimal design of the macrocyclic unit that leads to columnar assembly in high fidelity and probe the feasibility of incorporating a second functional group within the macrocycles. The porous molecular crystals prepared through the self-assembly of bis-urea macrocycles display surface areas similar to zeolites but lower than MOFs. Their simple one-dimensional channels are well-suited for studying binding, investigating transport, diffusion and exchange, and monitoring the effects of encapsulation on reaction mechanism and product distribution. Guests that complement the size, shape, and polarity of the channels can be absorbed into these porous crystals with repeatable stoichiometry to form solid host-guest complexes. Heating or extraction with an organic solvent enables desorption or removal of the guest and subsequent recovery of the solid host. Further, these porous crystals can be used as containers for the selective [2 + 2] cycloadditions of small enones such as 2-cyclohexenone or 3

  5. Urease-independent chemotactic responses of Helicobacter pylori to urea, urease inhibitors, and sodium bicarbonate.

    OpenAIRE

    Mizote, T; Yoshiyama, H; T. Nakazawa

    1997-01-01

    Helicobacter pylori CPY3401 and an isogenic urease-negative mutant, HPT73, showed chemotactic responses to urea, flurofamide (a potent urease inhibitor), and sodium bicarbonate. Since urea and sodium bicarbonate are secreted through the gastric epithelial surface and hydrolysis of urea by urease on the bacterial surface is essential for colonization, the chemotactic response of H. pylori may be crucial for its colonization and persistence in the stomach.

  6. Effects of Urea and Copper Sulphate on Some Serum Biochemical and Meat Parameters in Broiler Chicken

    Directory of Open Access Journals (Sweden)

    A. Rasool, M. Tariq Javed*, Masood Akhtar1, S. Shabbir Bhatti, M. N. Shahzad and Riaz Hussain2

    2013-01-01

    Full Text Available In this study we analysed some of the serum enzymes, urea and creatinine to understand the pathological changes occurring in different organs of broilers due to urea and copper. The feeding for 15 days at or higher than 2% urea + 1gm copper sulphate caused significant rise in serum ALT, AST, AKP and creatinine. With further increase in time of 15 days, the levels of urea and LDH also increased significantly, this was seen even in birds fed 1% urea + 250 mg copper sulphate. We found increase in serum urea even in 1% urea fed birds and in all other groups where combination was used, however, serum creatinine increased significantly (P<0.05 only in birds fed 2% urea+1 gm copper sulphate or higher than these levels. The combined use of urea and copper sulphate resulted in changes in moisture, ash, crude protein and potassium in thigh and breast meat of broilers. The results of the present study suggest damaging effects of higher levels of urea and copper, alone or together and change in meat quality with lower protein contents and higher salt levels in meat of broilers. Thus the use of urea and copper sulphate together is not recommended in broilers, especially at 1% urea and 250mg copper sulphate or higher. The results of the study can be helpful to poultry farmers, pathologists and nutritionists who are involved in augmentation the meat quality and also to general public with special reference to people having hypertension as the meat salt levels may be higher with use of the these compounds in the broiler ration.

  7. Solution Properties of Soy Protein in DMSO/Urea Solvent System

    Institute of Scientific and Technical Information of China (English)

    XIAO Ru; YIN Duan; JIN Xin; SUN Gang

    2008-01-01

    Solution properties of 7S globulins (7S), 11S globulins (11S) and soy protein isolates (SPI) in dimethylsulfoxide ( DMSO )/urea solvent system were studied by intrinsic viscosity and particle size distributions.The results showed that the existence of urea was the main reason for the denaturation and solubility of soy protein in the system, and the effects were more obvious with increasing of urea concentration in solutions.Suitably dissolution temperature and time contributed to the solubility of soy proteins.

  8. Urea production in long-term cultures of adult rat hepatocytes.

    Science.gov (United States)

    Sierra-Santoyo, A; López, M L; Hernández, A; Mendoza-Figueroa, T

    1994-04-01

    To study the functionality of the urea cycle in long-term cultures of adult rat hepatocytes, urea production and the activity of two urea cycle enzymes were measured in hepatocytes cultured on 3T3 cells for 15 days. Urea production was also measured in cultures maintained with medium containing either 0.4 mm arginine or 0.4 mm ornithine and in cultures exposed to different concentrations of NH(4)Cl, an in vivo inducer of urea production. In hepatocytes seeded on 3T3 cells, urea production decreased gradually to 50% of the initial value after 15 days. Urea production was similar in 3T3-hepatocyte cultures maintained for 11 days with medium containing ornithine or arginine. Hepatocytes exposed for 24 hr to 1, 3 and 5 mm NH(4)Cl showed an average increase in urea production of 25, 50 and 69%, respectively, above that of unexposed cultures over 15 days. Ornithine transcarbamylase (OTC) activity decreased by 84% after 5 days in culture and remained constant thereafter, while arginase activity remained constant over 15 days. In contrast, in hepatocytes seeded on plastic substratum, urea production decreased to 24% of the initial value after 8 days in culture. OTC and arginase activities also decreased to 13 and 10% of their initial values after 8 days in culture. These results show that 3T3-hepatocyte cultures from adult rats produce urea from ornithine and/or arginine for at least 15 days and respond to an inducer of urea production as in vivo. They also show that these cultures have decreasing and constant levels of OTC and arginase activities, respectively, owing probably to an adaptative response dependent on substrate concentrations and hormonal regulation. These findings also suggest that 3T3-hepatocyte cultures are a suitable in vitro system to study urea production, its regulation by substrates and hormones and its alteration by drugs and toxic chemicals.

  9. Sodium Phenylbutyrate Decreases Plasma Branched-Chain Amino Acids in Patients with Urea Cycle Disorders

    OpenAIRE

    Burrage, Lindsay C.; Jain, Mahim; Gandolfo, Laura; Lee, Brendan H.; Nagamani, Sandesh CS

    2014-01-01

    Sodium phenylbutyrate (NaPBA) is a commonly used medication for the treatment of patients with urea cycle disorders (UCDs). Previous reports involving small numbers of patients with UCDs have shown that NaPBA treatment can result in lower plasma levels of the branched-chain amino acids (BCAA) but this has not been studied systematically. From a large cohort of patients (n=553) with UCDs enrolled in Longitudinal Study of Urea Cycle Disorders, a collaborative multicenter study of the Urea Cycle...

  10. Silicone Doped Chitosan-Acrylamide Coencapsulated Urea Fertilizer: An Approach to Controlled Release Fertilizers

    OpenAIRE

    Sempeho Ibahati Siafu

    2017-01-01

    In the absence of special management practices, urea is known to undergo chemical transformations resulting in severe losses (≈60–70%) of total fertilizer applied. In an attempt to design urea controlled release fertilizers in order to counterbalance the 60–70% loss, urea was cross-linked with chitosan and acrylamide under refluxed in situ copolymerization technique; the procedures were repeated with silicone doping prior cross-linking with MBA. The particles were characterized with FTIR/ATR,...

  11. Intercalation of urea into kaolinite for preparation of controlled release fertilizer

    OpenAIRE

    Mahdavi Fariba; Abdul Rashid Suraya; Khanif Yusop Mohd

    2014-01-01

    In this study urea was intercalated between layers of kaolinite by dry grinding technique to be used for preparing controlled release fertilizer. X-ray powder diffraction (XRPD) patterns confirmed the intercalation of urea into kaolinite by the significant expansion of the basal spacing of kaolinite layers from 0.710 nm to 1.090 nm. Fourier transform infrared spectroscopy (FT-IR) also confirmed the hydrogen bonding between urea and kaolinite. Based on CHNS ...

  12. Modular Sampling and Analysis Techniques for the Real-Time Analysis of Human Breath

    Energy Technology Data Exchange (ETDEWEB)

    Frank, M; Farquar, G; Adams, K; Bogan, M; Martin, A; Benner, H; Spadaccini, C; Steele, P; Davis, C; Loyola, B; Morgan, J; Sankaran, S

    2007-07-09

    At LLNL and UC Davis, we are developing several techniques for the real-time sampling and analysis of trace gases, aerosols and exhaled breath that could be useful for a modular, integrated system for breath analysis. Those techniques include single-particle bioaerosol mass spectrometry (BAMS) for the analysis of exhaled aerosol particles or droplets as well as breath samplers integrated with gas chromatography mass spectrometry (GC-MS) or MEMS-based differential mobility spectrometry (DMS). We describe these techniques and present recent data obtained from human breath or breath condensate, in particular, addressing the question of how environmental exposure influences the composition of breath.

  13. Effects of urea on the olfactory reception in zebrafish (Danio rerio

    Directory of Open Access Journals (Sweden)

    Lorenzo Gallus

    2016-06-01

    Full Text Available The effects of uremia on human olfactory functions have been clinically evaluated in various studies, even if to date it is not completely clarified which uremic toxins mediate these processes. Surprisingly, the role of the main molecule involved in uremia, urea indeed, has not been adequately investigated as other possible molecules may also be involved in uremic anosmia. The effects of urea on the olfaction have been evaluated in some clinical studies, but this is the first attempt to determine a direct action of urea on the olfactory epithelium of a vertebrate. Danio rerio adults were exposed to urea in different experiments to assess the effects on olfactory sensitivity and signal transduction. The analysis of the swimming speed has been used to evaluate the response to hypoxanthine 3-N-oxide (H3NO, a molecule that is known to elicit an olfactory-mediated alarm reaction in D. rerio. The presence and distribution of the G protein alpha subunit coupled to the olfactory receptors (Gαolf has been immunohistochemically investigated in the olfactory epithelium of control and urea-exposed D. rerio. Our findings showed that urea alters the response to H3NO of D. rerio with a quite rapid and reversible effect that appears to be independent from a mere interference of urea on the receptor-ligand binding. The Gαolf protein resulted increases after urea treatment, suggesting an effect of urea on its expression or degradation.

  14. Optical Tweezers Analysis of Double-Stranded DNA Denaturation in the Presence of Urea

    Science.gov (United States)

    Zhu, Chunli; Li, Jing

    2016-09-01

    Urea is a kind of denaturant prone to form hydrogen bonds with the electronegative centers of the nitrogenous bases, threatening the stability of hydrogen bonds between DNA base pairs. In this paper, the stability and stiffness of DNA double helix influenced by urea are investigated at single-molecule level using optical tweezers. Experimental results show that DNA's double helix stability and stiffness both decrease with increasing urea concentration. In addition, the re-forming of ruptured hydrogen bonds between the base pairs is blocked by urea as the tension on DNA is released.

  15. Imaging Renal Urea Handling in Rats at Millimeter Resolution using Hyperpolarized Magnetic Resonance Relaxometry

    Science.gov (United States)

    Reed, Galen D.; von Morze, Cornelius; Verkman, Alan S.; Koelsch, Bertram L.; Chaumeil, Myriam M.; Lustig, Michael; Ronen, Sabrina M.; Bok, Robert A.; Sands, Jeff M.; Larson, Peder E. Z.; Wang, Zhen J.; Larsen, Jan Henrik Ardenkjær; Kurhanewicz, John; Vigneron, Daniel B.

    2016-01-01

    In vivo spin spin relaxation time (T2) heterogeneity of hyperpolarized [13C,15N2]urea in the rat kidney was investigated. Selective quenching of the vascular hyperpolarized 13C signal with a macromolecular relaxation agent revealed that a long-T2 component of the [13C,15N2]urea signal originated from the renal extravascular space, thus allowing the vascular and renal filtrate contrast agent pools of the [13C,15N2]urea to be distinguished via multi-exponential analysis. The T2 response to induced diuresis and antidiuresis was performed with two imaging agents: hyperpolarized [13C,15N2]urea and a control agent hyperpolarized bis-1,1-(hydroxymethyl)-1-13C-cyclopropane-2H8. Large T2 increases in the inner-medullar and papilla were observed with the former agent and not the latter during antidiuresis. Therefore, [13C,15N2]urea relaxometry is sensitive to two steps of the renal urea handling process: glomerular filtration and the inner-medullary urea transporter (UT)-A1 and UT-A3 mediated urea concentrating process. Simple motion correction and subspace denoising algorithms are presented to aid in the multi exponential data analysis. Furthermore, a T2-edited, ultra long echo time sequence was developed for sub-2 mm3 resolution 3D encoding of urea by exploiting relaxation differences in the vascular and filtrate pools. PMID:27570835

  16. Concomitant polymorphs of 1,3-bis(3-fluorophenyl)urea.

    Science.gov (United States)

    Capacci-Daniel, Christina A; Bertke, Jeffery A; Dehghan, Shoaleh; Hiremath-Darji, Rupa; Swift, Jennifer A

    2016-09-01

    Hydrogen bonding between urea functionalities is a common structural motif employed in crystal-engineering studies. Crystallization of 1,3-bis(3-fluorophenyl)urea, C13H10F2N2O, from many solvents yielded concomitant mixtures of at least two polymorphs. In the monoclinic form, one-dimensional chains of hydrogen-bonded urea molecules align in an antiparallel orientation, as is typical of many diphenylureas. In the orthorhombic form, one-dimensional chains of hydrogen-bonded urea molecules have a parallel orientation rarely observed in symmetrically substituted diphenylureas.

  17. Quantum spin liquid in a breathing kagome lattice

    Science.gov (United States)

    Schaffer, Robert; Huh, Yejin; Hwang, Kyusung; Kim, Yong Baek

    2017-02-01

    Motivated by recent experiments on the vanadium oxyfluoride material DQVOF, we examine possible spin liquid phases on a breathing kagome lattice of S =1 /2 spins. By performing a projective symmetry group analysis, we determine the possible phases for both fermionic and bosonic Z2 spin liquids on this lattice, and establish the correspondence between the two. The nature of the ground state of the Heisenberg model on the isotropic kagome lattice is a hotly debated topic, with both Z2 and U(1) spin liquids argued to be plausible ground states. Using variational Monte Carlo techniques, we show that a gapped Z2 spin liquid emerges as the clear ground state in the presence of this breathing anisotropy. Our results suggest that the breathing anisotropy helps to stabilize this spin liquid ground state, which may aid us in understanding the results of experiments and help to direct future numerical studies on these systems.

  18. Liquid intake monitoring through breathing signal using machine learning

    Science.gov (United States)

    Dong, Bo; Biswas, Subir

    2013-05-01

    This paper presents the design, system structure and performance for a wireless and wearable diet monitoring system. Food and drink intake can be detected by the way of detecting a person's swallow events. The system works based on the key observation that a person's otherwise continuous breathing process is interrupted by a short apnea when she or he swallows as a part of solid or liquid intake process. We detect the swallows through the difference between normal breathing cycle and breathing cycle with swallows using a wearable chest-belt. Three popular machine learning algorithms have been applied on both time and frequency domain features. Discrimination power of features is then analyzed for applications where only small number of features is allowed. It is shown that high detection performance can be achieved with only few features.

  19. Wash-out of ambient air contaminations for breath measurements.

    Science.gov (United States)

    Maurer, F; Wolf, A; Fink, T; Rittershofer, B; Heim, N; Volk, T; Baumbach, J I; Kreuer, S

    2014-06-01

    In breath analysis, ambient air contaminations are ubiquitous and difficult to eliminate. This study was designed to investigate the reduction of ambient air background by a lung wash-out with synthetic air. The reduction of the initial ambient air volatile organic compound (VOC) intensity was investigated in the breath of 20 volunteers inhaling synthetic air via a sealed full face mask in comparison to inhaling ambient air. Over a period of 30 minutes, breath analysis was conducted using ion mobility spectrometry coupled to a multi-capillary column. A total of 68 VOCs were identified for inhaling ambient air or inhaling synthetic air. By treatment with synthetic air, 39 VOCs decreased in intensity, whereas 29 increased in comparison to inhaling ambient air. In total, seven VOCs were significantly reduced (P-value ambient air contaminations from the airways by a lung wash-out with synthetic air.

  20. Breathing detection with a portable impedance measurement system: first measurements.

    Science.gov (United States)

    Cordes, Axel; Foussier, Jerome; Leonhardt, Steffen

    2009-01-01

    For monitoring the health status of individuals, detection of breathing and heart activity is important. From an electrical point of view, it is known that breathing and heart activity change the electrical impedance distribution in the human body over the time due to ventilation (high impedance) and blood shifts (low impedance). Thus, it is possible to detect both important vital parameters by measuring the impedance of the thorax or the region around lung and heart. For some measurement scenarios it is also essential to detect these parameters contactless. For instance, monitoring bus drivers health could help to limit accidents, but directly connected systems limit the drivers free moving space. One measurement technology for measuring the impedance changes in the chest without cables is the magnetic impedance tomography (MIT). This article describes a portable measurement system we developed for this scenario that allows to measure breathing contactless. Furthermore, first measurements with five volunteers were performed and analyzed.