The gene dosage effect of the rad52 mutation on X-ray survival curves of tetraploid yeast strains

International Nuclear Information System (INIS)

Ho, K.S.Y.

1975-01-01

The mutation rad52 in the yeast Saccharomyces cerevisiae confers sensitivity to X-rays. The gene dosage effect of this mutation on X-ray survival curves of tetraploid yeast strains is shown. With increasing number of rad52 alleles, both a decrease in the survival for a given dose and a decrease in the survival curve shoulder width are observed. The generation of such a family of survival curves using three different mathematical models is discussed

Selecting the correct weighting factors for linear and quadratic calibration curves with least-squares regression algorithm in bioanalytical LC-MS/MS assays and impacts of using incorrect weighting factors on curve stability, data quality, and assay performance.

Science.gov (United States)

Gu, Huidong; Liu, Guowen; Wang, Jian; Aubry, Anne-Françoise; Arnold, Mark E

2014-09-16

A simple procedure for selecting the correct weighting factors for linear and quadratic calibration curves with least-squares regression algorithm in bioanalytical LC-MS/MS assays is reported. The correct weighting factor is determined by the relationship between the standard deviation of instrument responses (σ) and the concentrations (x). The weighting factor of 1, 1/x, or 1/x(2) should be selected if, over the entire concentration range, σ is a constant, σ(2) is proportional to x, or σ is proportional to x, respectively. For the first time, we demonstrated with detailed scientific reasoning, solid historical data, and convincing justification that 1/x(2) should always be used as the weighting factor for all bioanalytical LC-MS/MS assays. The impacts of using incorrect weighting factors on curve stability, data quality, and assay performance were thoroughly investigated. It was found that the most stable curve could be obtained when the correct weighting factor was used, whereas other curves using incorrect weighting factors were unstable. It was also found that there was a very insignificant impact on the concentrations reported with calibration curves using incorrect weighting factors as the concentrations were always reported with the passing curves which actually overlapped with or were very close to the curves using the correct weighting factor. However, the use of incorrect weighting factors did impact the assay performance significantly. Finally, the difference between the weighting factors of 1/x(2) and 1/y(2) was discussed. All of the findings can be generalized and applied into other quantitative analysis techniques using calibration curves with weighted least-squares regression algorithm.

SU-E-T-427: Cell Surviving Fractions Derived From Tumor-Volume Variation During Radiotherapy for Non-Small Cell Lung Cancer: Comparison with Predictive Assays

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Chvetsov, A; Schwartz, J; Mayr, N [University of Washington, Seattle, WA (United States); Yartsev, S [London Health Sciences Centre, London, Ontario (Canada)

2014-06-01

Purpose: To show that a distribution of cell surviving fractions S{sub 2} in a heterogeneous group of patients can be derived from tumor-volume variation curves during radiotherapy for non-small cell lung cancer. Methods: Our analysis was based on two data sets of tumor-volume variation curves for heterogeneous groups of 17 patients treated for nonsmall cell lung cancer with conventional dose fractionation. The data sets were obtained previously at two independent institutions by using megavoltage (MV) computed tomography (CT). Statistical distributions of cell surviving fractions S{sup 2} and cell clearance half-lives of lethally damaged cells T1/2 have been reconstructed in each patient group by using a version of the two-level cell population tumor response model and a simulated annealing algorithm. The reconstructed statistical distributions of the cell surviving fractions have been compared to the distributions measured using predictive assays in vitro. Results: Non-small cell lung cancer presents certain difficulties for modeling surviving fractions using tumor-volume variation curves because of relatively large fractional hypoxic volume, low gradient of tumor-volume response, and possible uncertainties due to breathing motion. Despite these difficulties, cell surviving fractions S{sub 2} for non-small cell lung cancer derived from tumor-volume variation measured at different institutions have similar probability density functions (PDFs) with mean values of 0.30 and 0.43 and standard deviations of 0.13 and 0.18, respectively. The PDFs for cell surviving fractions S{sup 2} reconstructed from tumor volume variation agree with the PDF measured in vitro. Comparison of the reconstructed cell surviving fractions with patient survival data shows that the patient survival time decreases as the cell surviving fraction increases. Conclusion: The data obtained in this work suggests that the cell surviving fractions S{sub 2} can be reconstructed from the tumor volume

SU-E-T-427: Cell Surviving Fractions Derived From Tumor-Volume Variation During Radiotherapy for Non-Small Cell Lung Cancer: Comparison with Predictive Assays

International Nuclear Information System (INIS)

Chvetsov, A; Schwartz, J; Mayr, N; Yartsev, S

2014-01-01

Purpose: To show that a distribution of cell surviving fractions S 2 in a heterogeneous group of patients can be derived from tumor-volume variation curves during radiotherapy for non-small cell lung cancer. Methods: Our analysis was based on two data sets of tumor-volume variation curves for heterogeneous groups of 17 patients treated for nonsmall cell lung cancer with conventional dose fractionation. The data sets were obtained previously at two independent institutions by using megavoltage (MV) computed tomography (CT). Statistical distributions of cell surviving fractions S 2 and cell clearance half-lives of lethally damaged cells T1/2 have been reconstructed in each patient group by using a version of the two-level cell population tumor response model and a simulated annealing algorithm. The reconstructed statistical distributions of the cell surviving fractions have been compared to the distributions measured using predictive assays in vitro. Results: Non-small cell lung cancer presents certain difficulties for modeling surviving fractions using tumor-volume variation curves because of relatively large fractional hypoxic volume, low gradient of tumor-volume response, and possible uncertainties due to breathing motion. Despite these difficulties, cell surviving fractions S 2 for non-small cell lung cancer derived from tumor-volume variation measured at different institutions have similar probability density functions (PDFs) with mean values of 0.30 and 0.43 and standard deviations of 0.13 and 0.18, respectively. The PDFs for cell surviving fractions S 2 reconstructed from tumor volume variation agree with the PDF measured in vitro. Comparison of the reconstructed cell surviving fractions with patient survival data shows that the patient survival time decreases as the cell surviving fraction increases. Conclusion: The data obtained in this work suggests that the cell surviving fractions S 2 can be reconstructed from the tumor volume variation curves measured

Relation of intracellular cyclic AMP to the shape of mammalian cell survival curves

International Nuclear Information System (INIS)

Lehnert, S.

1975-01-01

Results of experiments with V79 cells growing in tissue culture indicate that the reproductive survival of cells following irradiation is influenced by the level of intracellular 3', 5'-cyclic adenosine monophosphate (cyclic AMP) at the time of irradiation. Cells containing high levels of cyclic AMP induced by treatments with drugs show a characteristic survival curve in which the extent of the shoulder is increased so that the survival after low doses is enhanced. The exponential slope or D 0 , however, is decreased so that at high doses the survival of cells containing high levels of cyclic AMP may be less than that of controls. Naturally occurring changes in radiosensitivity such as those observed as cells pass through the division cycle, may also be related to parallel changes in cyclic AMP concentration occurring during the cycle. Injection of mice with compounds producing elevated cyclic AMP prior to whole-body irradiation increases survival at seven days post-irradiation. The shape of the survival curve for intestinal stem cells in these mice differs from that of the control in having an increased extrapolation number; no change in D 0 is observed in this in vivo situation. (author)

In vitro effects of piracetam on the radiosensitivity of hypoxic cells (adaptation of MTT assay to hypoxic conditions)

International Nuclear Information System (INIS)

Gheuens, E.E.O.; Bruijn, E.A. de; Van der Heyden, S.; Van Oosterom, A.T.; Lagarde, P.; Pooter, C.M.J. de; Chomy, F.

1995-01-01

This paper describes the adaptation of the MTT assay to hypoxic conditions in order to test the in vitro effect of piracetam on hypoxic cells and particularly on the radiosensitivity of hypoxic cells since this drug has shown clinical effect on acute and chronic hypoxia. The V79 cell line was selected by reference to preliminary hypoxic experiments using clonogenic assay and euoxic experiments using clonogenic and MTT assays. Cell growth and survival in our hypoxic conditions were assessed using MTT assay with an enclosure and special 48-well plates both made of glass. Growth curves on glass plates after 1-hour exposure to nitrogen versus air were comparable, so there is no bias effect due to gas composition. Survival curves using MTT versus reference clonogenic assay were comparable after radiation exposure in eu- and hypoxic conditions, and confirm the validity of our original technique for creating hypoxia. The Oxygen Enhancement Ratio was of about 3 for 1-hour hypoxic exposure. Piracetam gave no cytotoxic effect up to 10 mM of piracetam. Growth curves after continuous drug exposure and 1-hour euoxic versus hypoxic exposure gave no cytotoxic effect up to 10 mM of piracetam. Survival curves after continuous drug exposure to 10 mM of piracetam gave no significant effect on the radiosensitivity of hypoxic V79 cells using MTT or clonogenic assay. (author). 32 refs., 6 figs

Implications of tissue target-cell survival-curve shape for values of split-dose recovery doses: late versus early effects

International Nuclear Information System (INIS)

Redpath, J.L.; Peel, D.M.; Hopewell, J.W.

1984-01-01

Recent data from this laboratory on split-dose recovery for early and late effects in pig skin are consistent with the linear-quadratic model for cell survival, and with relative cell survival-curve shapes for early- and late-effect target cells where the early-effect cells have an intially steeper and straighter survival-curve than the late-effect cells. (author)

Exponential Decay Nonlinear Regression Analysis of Patient Survival Curves: Preliminary Assessment in Non-Small Cell Lung Cancer

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Stewart, David J.; Behrens, Carmen; Roth, Jack; Wistuba, Ignacio I.

2010-01-01

Background For processes that follow first order kinetics, exponential decay nonlinear regression analysis (EDNRA) may delineate curve characteristics and suggest processes affecting curve shape. We conducted a preliminary feasibility assessment of EDNRA of patient survival curves. Methods EDNRA was performed on Kaplan-Meier overall survival (OS) and time-to-relapse (TTR) curves for 323 patients with resected NSCLC and on OS and progression-free survival (PFS) curves from selected publications. Results and Conclusions In our resected patients, TTR curves were triphasic with a “cured” fraction of 60.7% (half-life [t1/2] >100,000 months), a rapidly-relapsing group (7.4%, t1/2=5.9 months) and a slowly-relapsing group (31.9%, t1/2=23.6 months). OS was uniphasic (t1/2=74.3 months), suggesting an impact of co-morbidities; hence, tumor molecular characteristics would more likely predict TTR than OS. Of 172 published curves analyzed, 72 (42%) were uniphasic, 92 (53%) were biphasic, 8 (5%) were triphasic. With first-line chemotherapy in advanced NSCLC, 87.5% of curves from 2-3 drug regimens were uniphasic vs only 20% of those with best supportive care or 1 drug (p<0.001). 54% of curves from 2-3 drug regimens had convex rapid-decay phases vs 0% with fewer agents (p<0.001). Curve convexities suggest that discontinuing chemotherapy after 3-6 cycles “synchronizes” patient progression and death. With postoperative adjuvant chemotherapy, the PFS rapid-decay phase accounted for a smaller proportion of the population than in controls (p=0.02) with no significant difference in rapid-decay t1/2, suggesting adjuvant chemotherapy may move a subpopulation of patients with sensitive tumors from the relapsing group to the cured group, with minimal impact on time to relapse for a larger group of patients with resistant tumors. In untreated patients, the proportion of patients in the rapid-decay phase increased (p=0.04) while rapid-decay t1/2 decreased (p=0.0004) with increasing

Mathematical analysis of 51Cr-labelled red cell survival curves in congenital haemolytic anaemias

International Nuclear Information System (INIS)

Kasfiki, A.G.; Antipas, S.E.; Dimitriou, P.A.; Gritzali, F.A.; Melissinos, K.G.

1982-01-01

The parameters of 51 Cr labelled red cell survival curves were calculated in 26 patients with homozygous β-thalassaemia, 8 with sickle-cell anaemia and 3 with s-β-thalassaemia, using a non-linear weighted least squares analysis computer program. In thalassaemic children the calculated parameters denote that the shorting of the mean cell life is due to early senescence alone, while there is some evidence that in thalassaemic adults additional extracellular destruction mechanisms participate as well. Red cell survival curves from patients with sickle-cell anaemia and s-β-thalassaemia resemble each other, while their parameters indicate an initial rapid loss of radioactivity, early senescence and the presence of extracellular red cell destruction factors. (orig.)

Evaluating methodological assumptions of a catch-curve survival estimation of unmarked precocial shorebird chickes

Science.gov (United States)

McGowan, Conor P.; Gardner, Beth

2013-01-01

Estimating productivity for precocial species can be difficult because young birds leave their nest within hours or days of hatching and detectability thereafter can be very low. Recently, a method for using a modified catch-curve to estimate precocial chick daily survival for age based count data was presented using Piping Plover (Charadrius melodus) data from the Missouri River. However, many of the assumptions of the catch-curve approach were not fully evaluated for precocial chicks. We developed a simulation model to mimic Piping Plovers, a fairly representative shorebird, and age-based count-data collection. Using the simulated data, we calculated daily survival estimates and compared them with the known daily survival rates from the simulation model. We conducted these comparisons under different sampling scenarios where the ecological and statistical assumptions had been violated. Overall, the daily survival estimates calculated from the simulated data corresponded well with true survival rates of the simulation. Violating the accurate aging and the independence assumptions did not result in biased daily survival estimates, whereas unequal detection for younger or older birds and violating the birth death equilibrium did result in estimator bias. Assuring that all ages are equally detectable and timing data collection to approximately meet the birth death equilibrium are key to the successful use of this method for precocial shorebirds.

Multiplex real-time PCR assay for the detection of extended-spectrum β-lactamase and carbapenemase genes using melting curve analysis.

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Singh, Prashant; Pfeifer, Yvonne; Mustapha, Azlin

2016-05-01

Real-time PCR melt curve assays for the detection of β-lactamase, extended-spectrum β-lactamase and carbapenemase genes in Gram-negative bacteria were developed. Two multiplex real-time PCR melt curve assays were developed for the detection of ten common β-lactamase genes: blaKPC-like, blaOXA-48-like, blaNDM-like, blaVIM-like, blaIMP-like, blaCTX-M-1+2-group, blaCMY-like, blaACC-like, blaSHV-like and blaTEM-like. The assays were evaluated using 25 bacterial strains and 31 DNA samples (total n=56) comprising different Enterobacteriaceae genera and Pseudomonas spp. These strains were previously characterized at five research institutes. Each resistance gene targeted in this study generated a non-overlapping and distinct melt curve peak. The assay worked effectively and detected the presence of additional resistance genes in 23 samples. The assays developed in this study offer a simple, low cost method for the detection of prevalent β-lactamase, ESBL and carbapenemase genes among Gram-negative pathogens. Copyright © 2016 Elsevier B.V. All rights reserved.

Finding Risk Groups by Optimizing Artificial Neural Networks on the Area under the Survival Curve Using Genetic Algorithms.

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Kalderstam, Jonas; Edén, Patrik; Ohlsson, Mattias

2015-01-01

We investigate a new method to place patients into risk groups in censored survival data. Properties such as median survival time, and end survival rate, are implicitly improved by optimizing the area under the survival curve. Artificial neural networks (ANN) are trained to either maximize or minimize this area using a genetic algorithm, and combined into an ensemble to predict one of low, intermediate, or high risk groups. Estimated patient risk can influence treatment choices, and is important for study stratification. A common approach is to sort the patients according to a prognostic index and then group them along the quartile limits. The Cox proportional hazards model (Cox) is one example of this approach. Another method of doing risk grouping is recursive partitioning (Rpart), which constructs a decision tree where each branch point maximizes the statistical separation between the groups. ANN, Cox, and Rpart are compared on five publicly available data sets with varying properties. Cross-validation, as well as separate test sets, are used to validate the models. Results on the test sets show comparable performance, except for the smallest data set where Rpart's predicted risk groups turn out to be inverted, an example of crossing survival curves. Cross-validation shows that all three models exhibit crossing of some survival curves on this small data set but that the ANN model manages the best separation of groups in terms of median survival time before such crossings. The conclusion is that optimizing the area under the survival curve is a viable approach to identify risk groups. Training ANNs to optimize this area combines two key strengths from both prognostic indices and Rpart. First, a desired minimum group size can be specified, as for a prognostic index. Second, the ability to utilize non-linear effects among the covariates, which Rpart is also able to do.

Statistical inference methods for two crossing survival curves: a comparison of methods.

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Li, Huimin; Han, Dong; Hou, Yawen; Chen, Huilin; Chen, Zheng

2015-01-01

A common problem that is encountered in medical applications is the overall homogeneity of survival distributions when two survival curves cross each other. A survey demonstrated that under this condition, which was an obvious violation of the assumption of proportional hazard rates, the log-rank test was still used in 70% of studies. Several statistical methods have been proposed to solve this problem. However, in many applications, it is difficult to specify the types of survival differences and choose an appropriate method prior to analysis. Thus, we conducted an extensive series of Monte Carlo simulations to investigate the power and type I error rate of these procedures under various patterns of crossing survival curves with different censoring rates and distribution parameters. Our objective was to evaluate the strengths and weaknesses of tests in different situations and for various censoring rates and to recommend an appropriate test that will not fail for a wide range of applications. Simulation studies demonstrated that adaptive Neyman's smooth tests and the two-stage procedure offer higher power and greater stability than other methods when the survival distributions cross at early, middle or late times. Even for proportional hazards, both methods maintain acceptable power compared with the log-rank test. In terms of the type I error rate, Renyi and Cramér-von Mises tests are relatively conservative, whereas the statistics of the Lin-Xu test exhibit apparent inflation as the censoring rate increases. Other tests produce results close to the nominal 0.05 level. In conclusion, adaptive Neyman's smooth tests and the two-stage procedure are found to be the most stable and feasible approaches for a variety of situations and censoring rates. Therefore, they are applicable to a wider spectrum of alternatives compared with other tests.

Discrimination measures for survival outcomes: connection between the AUC and the predictiveness curve.

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Viallon, Vivian; Latouche, Aurélien

2011-03-01

Finding out biomarkers and building risk scores to predict the occurrence of survival outcomes is a major concern of clinical epidemiology, and so is the evaluation of prognostic models. In this paper, we are concerned with the estimation of the time-dependent AUC--area under the receiver-operating curve--which naturally extends standard AUC to the setting of survival outcomes and enables to evaluate the discriminative power of prognostic models. We establish a simple and useful relation between the predictiveness curve and the time-dependent AUC--AUC(t). This relation confirms that the predictiveness curve is the key concept for evaluating calibration and discrimination of prognostic models. It also highlights that accurate estimates of the conditional absolute risk function should yield accurate estimates for AUC(t). From this observation, we derive several estimators for AUC(t) relying on distinct estimators of the conditional absolute risk function. An empirical study was conducted to compare our estimators with the existing ones and assess the effect of model misspecification--when estimating the conditional absolute risk function--on the AUC(t) estimation. We further illustrate the methodology on the Mayo PBC and the VA lung cancer data sets. Copyright © 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Analysis of survival curves for Rhizopus, Mucor and Penicillia irradiated with gamma radiation

International Nuclear Information System (INIS)

Ishiguro, Etsuji; Danno, Akibumi; Miyazato, Mitsuru

1994-01-01

This study was aimed to understand the survival pattern of some microorganisms which were treated by γ-sterilization. Though most of the works were concentrated and reported with D 10 -values, it was presently found that the γ-irradiated survival curves showed sigmoid pattern and L-values were reached about half of the D 10 -value for each strains. It was further confirmed that if L-values were used for practical sterilization with D 10 -values, the estimation of sterilized levels would become more accurate. (author). 10 refs., 3 figs., 1 tab

Similarity criterion analysis of dose-response curves in biological assay and radioimmunoassay of hormones

International Nuclear Information System (INIS)

Cristakou, H.D.

1983-01-01

The difficulties involved in the control of biological and radioimmunological assay systems, and in the maintenance of standard, as well as, the usual heterogeneity of assayed samples require some evidence of similarity between the dose-response curves obtained with the standard and the sample. Nowadays the parallelism test is used to provide such evidence. However, some indications of non-normal errors distribution, such as the presence of out layers, render the parallelism test both conceptually implausible and statistically inefficient. In such a manner we suggest the non-parametric 'frequencial' test as a more sounding option. (author)

Universal Survival Curve and Single Fraction Equivalent Dose: Useful Tools in Understanding Potency of Ablative Radiotherapy

International Nuclear Information System (INIS)

Park, Clint; Papiez, Lech; Zhang Shichuan; Story, Michael; Timmerman, Robert D.

2008-01-01

Purpose: Overprediction of the potency and toxicity of high-dose ablative radiotherapy such as stereotactic body radiotherapy (SBRT) by the linear quadratic (LQ) model led to many clinicians' hesitating to adopt this efficacious and well-tolerated therapeutic option. The aim of this study was to offer an alternative method of analyzing the effect of SBRT by constructing a universal survival curve (USC) that provides superior approximation of the experimentally measured survival curves in the ablative, high-dose range without losing the strengths of the LQ model around the shoulder. Methods and Materials: The USC was constructed by hybridizing two classic radiobiologic models: the LQ model and the multitarget model. We have assumed that the LQ model gives a good description for conventionally fractionated radiotherapy (CFRT) for the dose to the shoulder. For ablative doses beyond the shoulder, the survival curve is better described as a straight line as predicted by the multitarget model. The USC smoothly interpolates from a parabola predicted by the LQ model to the terminal asymptote of the multitarget model in the high-dose region. From the USC, we derived two equivalence functions, the biologically effective dose and the single fraction equivalent dose for both CFRT and SBRT. Results: The validity of the USC was tested by using previously published parameters of the LQ and multitarget models for non-small-cell lung cancer cell lines. A comparison of the goodness-of-fit of the LQ and USC models was made to a high-dose survival curve of the H460 non-small-cell lung cancer cell line. Conclusion: The USC can be used to compare the dose fractionation schemes of both CFRT and SBRT. The USC provides an empirically and a clinically well-justified rationale for SBRT while preserving the strengths of the LQ model for CFRT

Survival curves and cell restoration of gamma irradiated chlorella

International Nuclear Information System (INIS)

Gilet, Roland

1970-01-01

The characteristics of the living material used and the cultures developed are defined. The irradiation techniques and the dosimetry methods used are described. The clonal growth in a gelified nutrient solution was studied and the survival curves, which are very reproducible when anoxic conditions are eliminated, were established. It is shown that the radiosensitivity of Chlorella decreases with the age of the culture when the plateau of the growth curve is reached, and that for synchronous cells it varies slightly with the phase in the cycle at which the radiation is received. The restoration from sublethal damage occurs quickly and does not depend upon the continuation of the cell cycle when no multiplication occurs during the experiments and is not modified by anoxic conditions. The restoration rate is reduced at 0 deg. C. It explains the variations in the apparent radiosensitivity with the dose rate. In contrast with the results published for many cells, the restoration is incomplete. The problem of the elimination of sublethal damage during clonal development is posed. A model summarizing the experimental results and suggesting future work is given. (author) [fr

Hemopoietic stem-cell compartment of the SCID mouse: Double-exponential survival curve after γ irradiation

International Nuclear Information System (INIS)

Taniguchi, Satoshi; Hirabayashi, Yoko; Inoue, Tohru; Kanisawa, Masayoshi; Sasaki, Hideki; Komatsu, Kenshi; Mori, K.J.

1993-01-01

It has been reported that SCID (severe combined immunodeficiency, scid/scid) mice are more radiosensitive than normal mice. In the present studies, graded doses of radiation were given to bone marrow cells from SCID mice, and double-exponential survival curves were observed for day-9 and day-12 colony-forming units in the spleen (CFU-S). Single-exponential curves were found for SCID CFU in in vitro assays for granulocyte/macrophage-CFUs and erythroid burst-forming units, as reported elsewhere. Since the size of this more resistant fraction seems to decrease with stem-cell maturation, the finding implies that this fraction is a primitive subpopulation of the stem-cell compartment. The mean lethal dose (D 0 ), however, of this less sensitive SCID CFU-S is much less than the D 0 of regular CFU-S in normal littermates. Spleen colonies produced by SCID bone marrow were relatively small and abortive. The size of these colonies decreased nearly exponentially with increasing doses of radiation. These colonies produced by the sensitive fraction have disappeared, being killed by a relatively low dose of radiation. This observation might account for the high lymphomagenesis arising from primitive hemopoietic stem cells in SCID mice, because the smallness of the colonies suggests that there is unrepaired or misrepaired damage. Furthermore, this less sensitive fraction might be a source of the open-quotes leakyclose quotes change of T and B cells, possibly due to the induction of an equivocal repair system which appears in the later stages of life in the SCID mice. 34 refs., 5 figs., 3 tabs

Statistical study of clone survival curves after irradiation in one or two stages. Comparison and generalization of different models

International Nuclear Information System (INIS)

Lachet, Bernard.

1975-01-01

A statistical study was carried out on 208 survival curves for chlorella subjected to γ or particle radiations. The computing programmes used were written in Fortran. The different experimental causes contributing to the variance of a survival rate are analyzed and consequently the experiments can be planned. Each curve was fitted to four models by the weighted least squares method applied to non-linear functions. The validity of the fits obtained can be checked by the F test. It was possible to define the confidence and prediction zones around an adjusted curve by weighting of the residual variance, in spite of error on the doses delivered; the confidence limits can them be fixed for a dose estimated from an exact or measured survival. The four models adopted were compared for the precision of their fit (by a non-parametric simultaneous comparison test) and the scattering of their adjusted parameters: Wideroe's model gives a very good fit with the experimental points in return for a scattering of its parameters, which robs them of their presumed meaning. The principal component analysis showed the statistical equivalence of the 1 and 2 hit target models. Division of the irradiation into two doses, the first fixed by the investigator, leads to families of curves for which the equation was established from that of any basic model expressing the dose survival relationship in one-stage irradiation [fr

Applications of high-throughput clonogenic survival assays in high-LET particle microbeams

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Antonios eGeorgantzoglou

2016-01-01

Full Text Available Charged particle therapy is increasingly becoming a valuable tool in cancer treatment, mainly due to the favorable interaction of particle radiation with matter. Its application is still limited due, in part, to lack of data regarding the radiosensitivity of certain cell lines to this radiation type, especially to high-LET particles. From the earliest days of radiation biology, the clonogenic survival assay has been used to provide radiation response data. This method produces reliable data but it is not optimized for high-throughput microbeam studies with high-LET radiation where high levels of cell killing lead to a very low probability of maintaining cells’ clonogenic potential. A new method, therefore, is proposed in this paper, which could potentially allow these experiments to be conducted in a high-throughput fashion. Cells are seeded in special polypropylene dishes and bright-field illumination provides cell visualization. Digital images are obtained and cell detection is applied based on corner detection, generating individual cell targets as x-y points. These points in the dish are then irradiated individually by a micron field size high-LET microbeam. Post-irradiation, time-lapse imaging follows cells’ response. All irradiated cells are tracked by linking trajectories in all time-frames, based on finding their nearest position. Cell divisions are detected based on cell appearance and individual cell temporary corner density. The number of divisions anticipated is low due to the high probability of cell killing from high-LET irradiation. Survival curves are produced based on cell’s capacity to divide at least 4-5 times. The process is repeated for a range of doses of radiation. Validation shows the efficiency of the proposed cell detection and tracking method in finding cell divisions.

Applications of High-Throughput Clonogenic Survival Assays in High-LET Particle Microbeams.

Science.gov (United States)

Georgantzoglou, Antonios; Merchant, Michael J; Jeynes, Jonathan C G; Mayhead, Natalie; Punia, Natasha; Butler, Rachel E; Jena, Rajesh

2015-01-01

Charged particle therapy is increasingly becoming a valuable tool in cancer treatment, mainly due to the favorable interaction of particle radiation with matter. Its application is still limited due, in part, to lack of data regarding the radiosensitivity of certain cell lines to this radiation type, especially to high-linear energy transfer (LET) particles. From the earliest days of radiation biology, the clonogenic survival assay has been used to provide radiation response data. This method produces reliable data but it is not optimized for high-throughput microbeam studies with high-LET radiation where high levels of cell killing lead to a very low probability of maintaining cells' clonogenic potential. A new method, therefore, is proposed in this paper, which could potentially allow these experiments to be conducted in a high-throughput fashion. Cells are seeded in special polypropylene dishes and bright-field illumination provides cell visualization. Digital images are obtained and cell detection is applied based on corner detection, generating individual cell targets as x-y points. These points in the dish are then irradiated individually by a micron field size high-LET microbeam. Post-irradiation, time-lapse imaging follows cells' response. All irradiated cells are tracked by linking trajectories in all time-frames, based on finding their nearest position. Cell divisions are detected based on cell appearance and individual cell temporary corner density. The number of divisions anticipated is low due to the high probability of cell killing from high-LET irradiation. Survival curves are produced based on cell's capacity to divide at least four to five times. The process is repeated for a range of doses of radiation. Validation shows the efficiency of the proposed cell detection and tracking method in finding cell divisions.

The modified high-density survival assay is the useful tool to predict the effectiveness of fractionated radiation exposure

International Nuclear Information System (INIS)

Kuwahara, Yoshikazu; Mori, Miyuki; Oikawa, Toshiyuki; Shimura, Tsutomu; Fukumoto, Manabu; Ohtake, Yosuke; Ohkubo, Yasuhito; Mori, Shiro

2010-01-01

The high-density survival (HDS) assay was originally elaborated to assess cancer cell responses to therapeutic agents under the influence of intercellular communication. Here, we simplified the original HDS assay and studied its applicability for the detection of cellular radioresistance. We have recently defined clinically relevant radioresistant (CRR) cells, which continue to proliferate with daily exposure to 2 gray (Gy) of X-rays for more than 30 days in vitro. We established human CRR cell lines, HepG2-8960-R from HepG2, and SAS-R1 and -R2 from SAS, respectively. In an attempt to apply the HDS assay to detect radioresistance with clinical relevance, we simplified the original HDS assay by scoring the total number of surviving cells after exposure to X-rays. The modified HDS assay successfully detected radioresistance with clinical relevance. The modified HDS assay detected CRR phenotype, which is not always detectable by clonogenic assay. Therefore, we believe that the modified HDS assay presented in this study is a powerful tool to predict the effectiveness of fractionated radiotherapy against malignant tumors. (author)

Monte Carlo model to simulate the effects of DNA damage resulting from accumulation of 125I decays during development of colonies and clonogenic survival assays

International Nuclear Information System (INIS)

Lobachevsky, P.; Karagiannis, T.; Martin, R.F.

1998-01-01

Full text: Exposure of cultured cells to an internal source of ionising radiation, such as a radioactive isotope, differs substantially from external irradiation in the determination of delivered dose. In some cases, the radioactive isotope cannot be quickly and completely removed from cells before plating for clonogenic survival assay. This provides an additional dose of irradiation which is not easy to calculate. The contribution of this phenomenon to the cell survival is especially important if a radioactive isotope is incorporated into DNA, or a DNA-binding ligand is labelled with the isotope. The correction of the cell survival due to additional dose cannot be calculated using a simple analytical expression, since the isotope is present in the cells during colony growth. We have developed a Monte Carlo model which simulates the process of the colony growth, and takes into account the extent of damage from isotope decays accumulated between consequent cell divisions. The model considers such factors as cell cycle time, radiosensitivity, colony growth inhibition, isotope specific (per cell) activity, partition of isotope in daughter cells, isotope half-life time, isotope efflux. The model allows estimation of the impact of the irradiation during colony formation on the distribution of colony size, and on the calculation of the survival correction factor, which depends mainly on the isotope cell-specific activity. We applied the model to interpret the difference in survival of K652 cells exposed to 125 I decays with various cell-specific activities: 0.45, 3.21 and 7.42 decays/cell/hour. The cells were treated with 125 I - labelled Hoechst 33258 which binds to DNA in cell nucleus. After accumulation of 125 I decays under non-growth conditions, cells were plated for clonogenic survival assay. The survival correction factors calculated from the model for the given values of 125 I cell-specific activity are in good correlation with differences between experimental

The effect of ploidy on the modification of the shoulder region of hypoxic cell-survival curves by the biradical, Ro.03-6061

International Nuclear Information System (INIS)

Millar, B.C.; Millar, J.L.

1977-01-01

The biradical nitroxyl, Ro.03-6061, sensitized two lines of mouse L cell to ionizing radiation when the cells were rendered hypoxic. Although the biradical reduced the D 0 value of the hypoxic cell-survival curve in each instance, it had no significant effect on the shoulder region. A hybrid line produced from these two strains was more radioresistant than either parent. In this instance, the biradical suppressed the shoulder region of the hypoxic cell-survival curve, but had no effect on the D 0 value. In a second system, the biradical selectivity sensitized hypoxic cells of a diploid and a tetraploid clone of Syrian hamster cells (BHK21/C15). The survival-curve characteristics of both clones were similar. The biradical reduced the D 0 value but did not significantly change the shoulder region of the hypoxic cell-survival curve. An aneuploid line sub-cultured from the tetraploid clone was much more resistant to radiation. In this instance, there was a decrease in the D 0 value of hypoxic cells in the presence of the biradical, but the extrapolation number was increased to a value similar to that for cells irradiated in air. (author)

Mathematical simulation of influence of irradiated cell reparative system saturation on cell survival. Communication 1. Simulation of survival curves in prokaryotes

International Nuclear Information System (INIS)

Knyigavko, V.G.; Meshcheryakova, O.P.; Radzyishevs'ka, Je.B.

2004-01-01

Mathematical models of the processes of forming survival curves for prokaryotes which are based on the idea about the possibility of saturation of radiation lesion reparation systems of DNA of the irradiated cells at the dose increase were worked out. For the simplest of the discussed models the authors discuss the question about the methods of evaluation of the model parameters

SU-E-T-429: Uncertainties of Cell Surviving Fractions Derived From Tumor-Volume Variation Curves

International Nuclear Information System (INIS)

Chvetsov, A

2014-01-01

Purpose: To evaluate uncertainties of cell surviving fraction reconstructed from tumor-volume variation curves during radiation therapy using sensitivity analysis based on linear perturbation theory. Methods: The time dependent tumor-volume functions V(t) have been calculated using a twolevel cell population model which is based on the separation of entire tumor cell population in two subpopulations: oxygenated viable and lethally damaged cells. The sensitivity function is defined as S(t)=[δV(t)/V(t)]/[δx/x] where δV(t)/V(t) is the time dependent relative variation of the volume V(t) and δx/x is the relative variation of the radiobiological parameter x. The sensitivity analysis was performed using direct perturbation method where the radiobiological parameter x was changed by a certain error and the tumor-volume was recalculated to evaluate the corresponding tumor-volume variation. Tumor volume variation curves and sensitivity functions have been computed for different values of cell surviving fractions from the practically important interval S 2 =0.1-0.7 using the two-level cell population model. Results: The sensitivity functions of tumor-volume to cell surviving fractions achieved a relatively large value of 2.7 for S 2 =0.7 and then approached zero as S 2 is approaching zero Assuming a systematic error of 3-4% we obtain that the relative error in S 2 is less that 20% in the range S2=0.4-0.7. This Resultis important because the large values of S 2 are associated with poor treatment outcome should be measured with relatively small uncertainties. For the very small values of S2<0.3, the relative error can be larger than 20%; however, the absolute error does not increase significantly. Conclusion: Tumor-volume curves measured during radiotherapy can be used for evaluation of cell surviving fractions usually observed in radiation therapy with conventional fractionation

Random assay in radioimmunoassay: Feasibility and application compared with batch assay

Energy Technology Data Exchange (ETDEWEB)

Lee, Jung Min; Lee, Hwan Hee; Park, Sohyun; Kim, Tae Sung; Kim, Seok Ki [Dept. of Nuclear MedicineNational Cancer Center, Goyang (Korea, Republic of)

2016-12-15

The batch assay has been conventionally used for radioimmunoassay (RIA) because of its technical robustness and practical convenience. However, it has limitations in terms of the relative lag of report time due to the necessity of multiple assays in a small number of samples compared with the random assay technique. In this study, we aimed to verify whether the random assay technique can be applied in RIA and is feasible in daily practice. The coefficients of variation (CVs) of eight standard curves within a single kit were calculated in a CA-125 immunoradiometric assay (IRMA) for the reference of the practically ideal CV of the CA-125 kit. Ten standard curves of 10 kits from 2 prospectively collected lots (pLot) and 85 standard curves of 85 kits from 3 retrospectively collected lots (Lot) were obtained. Additionally, the raw measurement data of both 170 control references and 1123 patients' sera were collected retrospectively between December 2015 and January 2016. A standard curve of the first kit of each lot was used as a master standard curve for a random assay. The CVs of inter-kits were analyzed in each lot, respectively. All raw measurements were normalized by decay and radioactivity. The CA-125 values from control samples and patients' sera were compared using the original batch assay and random assay. In standard curve analysis, the CVs of inter-kits in pLots and Lots were comparable to those within a single kit. The CVs from the random assay with normalization were similar to those from the batch assay in the control samples (CVs % of low/high concentration; Lot1 2.71/1.91, Lot2 2.35/1.83, Lot3 2.83/2.08 vs. Lot1 2.05/1.21, Lot2 1.66/1.48, Lot3 2.41/2.14). The ICCs between the batch assay and random assay using patients' sera were satisfactory (Lot1 1.00, Lot2 0.999, Lot3 1.00). The random assay technique could be successfully applied to the conventional CA-125 IRMA kits. The random assay showed strong agreement with the batch assay. The

Evaluation of surviving fraction using nonclonogenic staining densitometry method

International Nuclear Information System (INIS)

Nishiguchi, Iku; Ogawa, Koichi; Ito, Hisao; Hashimoto, Shozo

1994-01-01

This study was performed to compare our nonclonogenic survival assay (densitometry assay, DM assay) with the widely used clonogenic assay. The established cell lines (HaLa, RMUG, IMR, GOTO) were grown in F 10 medium. The cells were spread in 24-well plates, irradiated with different doses, cultured for about one week and stained with crystal violet after the culture period. Taking the transparent images of the stained well on the light source with the CCD camera, the images were collected with the matrix size 64 x 64, and the integrated optical density of the entire surface of each well was determined by computer with our original program. As the number of cells in the well is reflected by its staining density, the surviving fraction was calculated as the fraction of growth in the irradiated wells relative to controls. The survival curves obtained by the densitometry method showed good correlations with those obtained by clonogenic assay. It is possible to predict intrinsic radiosensitivity with this assay, even if the cells do not form good colonies. However, this method is based on measurements in cultures which depend on the metabolism and growth kinetics of the irradiated cells. Cells should grow exponetially in the same manner in any well to obtain a result similar to that of clonogenic assay, although growth kinetics may be altered by irradiation. This, the endpoint must be strictly standardized. (author)

Clonogenic assay: adherent cells.

Science.gov (United States)

Rafehi, Haloom; Orlowski, Christian; Georgiadis, George T; Ververis, Katherine; El-Osta, Assam; Karagiannis, Tom C

2011-03-13

The clonogenic (or colony forming) assay has been established for more than 50 years; the original paper describing the technique was published in 1956. Apart from documenting the method, the initial landmark study generated the first radiation-dose response curve for X-ray irradiated mammalian (HeLa) cells in culture. Basically, the clonogenic assay enables an assessment of the differences in reproductive viability (capacity of cells to produce progeny; i.e. a single cell to form a colony of 50 or more cells) between control untreated cells and cells that have undergone various treatments such as exposure to ionising radiation, various chemical compounds (e.g. cytotoxic agents) or in other cases genetic manipulation. The assay has become the most widely accepted technique in radiation biology and has been widely used for evaluating the radiation sensitivity of different cell lines. Further, the clonogenic assay is commonly used for monitoring the efficacy of radiation modifying compounds and for determining the effects of cytotoxic agents and other anti-cancer therapeutics on colony forming ability, in different cell lines. A typical clonogenic survival experiment using adherent cells lines involves three distinct components, 1) treatment of the cell monolayer in tissue culture flasks, 2) preparation of single cell suspensions and plating an appropriate number of cells in petri dishes and 3) fixing and staining colonies following a relevant incubation period, which could range from 1-3 weeks, depending on the cell line. Here we demonstrate the general procedure for performing the clonogenic assay with adherent cell lines with the use of an immortalized human keratinocyte cell line (FEP-1811). Also, our aims are to describe common features of clonogenic assays including calculation of the plating efficiency and survival fractions after exposure of cells to radiation, and to exemplify modification of radiation-response with the use of a natural antioxidant

Development of a real-time PCR melt curve assay for simultaneous detection of virulent and antibiotic resistant Salmonella.

Science.gov (United States)

Singh, Prashant; Mustapha, Azlin

2014-12-01

Multiple drug resistance in Salmonella is an emerging problem in the area of food safety. Depending on the virulence and antibiotic resistance characteristics of the Salmonella strain, infections of varying severity could result. In this study, a multiplex melt curve real-time PCR assay for the detection of virulent and antibiotic resistance strains of Salmonella was developed with two primer sets. The first set targets the virulence gene, invasin (invA), and tetracycline (tetG), streptomycin (aadA2) and sulphonamide (sulI) antibiotic resistance genes, and the second set amplifies ampicillin (blaPSE,blaTEM) and chloramphenicol (floR) resistance genes. The multiplex assay was evaluated using 41 Salmonella strains and was further tested on eight different artificially inoculated food samples. The fluorescent DNA intercalating dye, SYTO9, generated high resolution melt curve peaks and, hence, was used for the development of the assay. This multiplex assay worked efficiently over a DNA concentration range of 20 ng-200 fg and showed a sensitivity of 290 CFU/mL with serially diluted broth cultures. The detection limit for un-enriched artificially inoculated food samples was 10(4) CFU/g, but an enrichment period of 6 h allowed for detection of 10 CFU/g of cells in the samples. Copyright © 2014 Elsevier Ltd. All rights reserved.

Factors determinating the shape of survival curves of Escherichia coli cells irradiated by ionizing radiation with different LET. Peculiarities of genom organization and the shape of survival curves

International Nuclear Information System (INIS)

Krasavin, E.A.

1984-01-01

The basic biological mechanisms realized on molecular, cellular and population levels and stipulating the shape of dependence of the cell suriival (S) on the dose (D) are considered. One of possible causes of nonlinear S(D) dependence are the peculiarities of DNA degradation in E. coli cells. The mechanisms of genetic control of different types of degradation are discussed. Some regularities of the genetic recombination and replication of DNA in E. coli are considered. The conclusion is made that one of the basic stipulating for the shoulder on the survival curves in E. coli are the peculiarities of the chromosome replication

In vitro effects of piracetam on the radiosensitivity of hypoxic cells (adaptation of MTT assay to hypoxic conditions); Effets in vitro du piracetam sur la radiosensibilite des cellules hypoxiques (adapatation du test au MTT aux conditions d`hypoxie)

Energy Technology Data Exchange (ETDEWEB)

Gheuens, E.E.O.; Bruijn, E.A. de; Van der Heyden, S.; Van Oosterom, A.T. [Universitaire Instelling Antwerpen, Antwerp (Belgium); Lagarde, P. [Universitaire Instelling Antwerpen, Antwerp (Belgium)]|[Institut Bergonie, 33 - Bordeaux (France); Pooter, C.M.J. de [Universitaire Instelling Antwerpen, Antwerp (Belgium)]|[Hopital de Middelheim, Anvers (Belgium); Chomy, F. [Institut Bergonie, 33 - Bordeaux (France)

1995-12-31

This paper describes the adaptation of the MTT assay to hypoxic conditions in order to test the in vitro effect of piracetam on hypoxic cells and particularly on the radiosensitivity of hypoxic cells since this drug has shown clinical effect on acute and chronic hypoxia. The V79 cell line was selected by reference to preliminary hypoxic experiments using clonogenic assay and euoxic experiments using clonogenic and MTT assays. Cell growth and survival in our hypoxic conditions were assessed using MTT assay with an enclosure and special 48-well plates both made of glass. Growth curves on glass plates after 1-hour exposure to nitrogen versus air were comparable, so there is no bias effect due to gas composition. Survival curves using MTT versus reference clonogenic assay were comparable after radiation exposure in eu- and hypoxic conditions, and confirm the validity of our original technique for creating hypoxia. The Oxygen Enhancement Ratio was of about 3 for 1-hour hypoxic exposure. Piracetam gave no cytotoxic effect up to 10 mM of piracetam. Growth curves after continuous drug exposure and 1-hour euoxic versus hypoxic exposure gave no cytotoxic effect up to 10 mM of piracetam. Survival curves after continuous drug exposure to 10 mM of piracetam gave no significant effect on the radiosensitivity of hypoxic V79 cells using MTT or clonogenic assay. (author). 32 refs., 6 figs.

The effect of sub-lethal damage repair and exchange on the final slope of cell survival curves

International Nuclear Information System (INIS)

Carlone, M.C.; Wilkins, D.E.; Raaphorst, G.P.

2003-01-01

Full text: The Lea-Catcheside dose rate protraction factor, G, is the most widely used model to describe the effects of dose rate on cell survival. In the linear quadratic formalism, this factor modifies the beta component of cell killing; G is greatest for acute irradiations while vanishing at low dose rates. We have found a simple compartmental model that can derive the Lea-Catcheside function. This compartmental model clearly shows that the G function can only be derived using a little known assumption: the diminution of sub-lethal damage due to exchange of repairable lesions is negligible compared to that due to repair. This assumption was explicitly stated by Lea, but it does not appear to have been restated or verified since very early work on cell survival. The implication of this assumption is that sub-lethal damage can be modeled without considering exchange, which is evidenced by the fact that the G function does not contain parameters relating to exchange. By using a new model that fully accounts for repair and exchange of sublethal lesions, a cell survival expression that has a modified G function, but that retains the linear quadratic formalism, can be obtained. At low doses, this new model predicts linear-quadratic behavior, but the behavior gradually changes to mono-exponential at high doses, which is consistent with experimental observations. Modeling cell survival of well-known survival curves using the modified linear quadratic model shows statistically significant improvement in the fits to the cell survival data as compared to best fits obtained with the linear quadratic model. It is shown that these improvements in fits are due to a superior representation of the high dose region of the survival curve

A three-parameter langmuir-type model for fitting standard curves of sandwich enzyme immunoassays with special attention to the α-fetoprotein assay

NARCIS (Netherlands)

Kortlandt, W.; Endeman, H.J.; Hoeke, J.O.O.

In a simplified approach to the reaction kinetics of enzyme-linked immunoassays, a Langmuir-type equation y = [ax/(b + x)] + c was derived. This model proved to be superior to logit-log and semilog models in the curve-fitting of standard curves. An assay for α-fetoprotein developed in our laboratory

Cell survival curves deduced from non-quantitative reactions of skin, intestinal mucosa and lung

International Nuclear Information System (INIS)

Dutreix, J.; Wambersie, A.

1975-01-01

The shape of the cell survival curve for the cell population relevant to some biological effects has been derived from the comparison of the total doses which result in the same biological effect for two irradiations delivered with N and 2N fractions in the same overall time. They show an initial slope which is interpreted as related to directly lethal, i.e. 'one-hit' or 'irreparable' events. The ratio of the initial slope and the slope at a dose D gives the contribution of the cell killing by directly lethal events relative to cell killing by accumulation of sublethal events. The bioligical effects which have been studied are: (i) dry desquamation of the skin of C 3 H mice and patients; (ii) intestinal death of BALB/c mice; and (iii) lung death of C 3 H mice. The shape of the cell survival curve has been found to be similar for skin desquamation and for intestinal death with a large contribution of lethal events, at single doses of 1000 rad. For lung death the initial tangent has a smaller slope and the shoulder is broader; this is interpreted as a relatively smaller contribution of lethal events with respect to accumulation of sublethal events. (author)

Three dimensions of the survival curve: horizontalization, verticalization, and longevity extension.

Science.gov (United States)

Cheung, Siu Lan Karen; Robine, Jean-Marie; Tu, Edward Jow-Ching; Caselli, Graziella

2005-05-01

Three dimensions of the survival curve have been developed: (1) "horizontalization," which corresponds to how long a cohort and how many survivors can live before aging-related deaths significantly decrease the proportion of survivors; (2) "verticalization," which corresponds to how concentrated aging-related ("normal") deaths are around the modal age at death (M); and (3) "longevity extension," which corresponds to how far the highest normal life durations can exceed M. Our study shows that the degree of horizontalization increased relatively less than the degree of verticalization in Hong Kong from 1976 to 2001. After age normalization, the highest normal life durations moved closer to M, implying that the increase in human longevity is meeting some resistance.

CFAssay: statistical analysis of the colony formation assay

International Nuclear Information System (INIS)

Braselmann, Herbert; Michna, Agata; Heß, Julia; Unger, Kristian

2015-01-01

Colony formation assay is the gold standard to determine cell reproductive death after treatment with ionizing radiation, applied for different cell lines or in combination with other treatment modalities. Associated linear-quadratic cell survival curves can be calculated with different methods. For easy code exchange and methodological standardisation among collaborating laboratories a software package CFAssay for R (R Core Team, R: A Language and Environment for Statistical Computing, 2014) was established to perform thorough statistical analysis of linear-quadratic cell survival curves after treatment with ionizing radiation and of two-way designs of experiments with chemical treatments only. CFAssay offers maximum likelihood and related methods by default and the least squares or weighted least squares method can be optionally chosen. A test for comparision of cell survival curves and an ANOVA test for experimental two-way designs are provided. For the two presented examples estimated parameters do not differ much between maximum-likelihood and least squares. However the dispersion parameter of the quasi-likelihood method is much more sensitive for statistical variation in the data than the multiple R 2 coefficient of determination from the least squares method. The dispersion parameter for goodness of fit and different plot functions in CFAssay help to evaluate experimental data quality. As open source software interlaboratory code sharing between users is facilitated

Mean inactivation dose: a useful concept for intercomparison of human cell survival curves

International Nuclear Information System (INIS)

Fertil, B.; Dertinger, H.; Courdi, A.; Malaise, E.P.

1984-01-01

The mean inactivation dose (anti D) is calculated for published in vitro survival curves obtained from cell lines of both normal and neoplastic human tissues. Cells belonging to different histological categories (melanomas, carcinomas, etc.) are shown to be characterized by distinct values of anti D which are related to the clinical radiosensitivity of tumors from these categories. Compared to other ways of representing in vitro radiosensitivity, e.g., by the multitarget parameters D 8 and n, the parameter anti D has several specific advantages

Analyzing survival curves at a fixed point in time for paired and clustered right-censored data

Science.gov (United States)

Su, Pei-Fang; Chi, Yunchan; Lee, Chun-Yi; Shyr, Yu; Liao, Yi-De

2018-01-01

In clinical trials, information about certain time points may be of interest in making decisions about treatment effectiveness. Rather than comparing entire survival curves, researchers can focus on the comparison at fixed time points that may have a clinical utility for patients. For two independent samples of right-censored data, Klein et al. (2007) compared survival probabilities at a fixed time point by studying a number of tests based on some transformations of the Kaplan-Meier estimators of the survival function. However, to compare the survival probabilities at a fixed time point for paired right-censored data or clustered right-censored data, their approach would need to be modified. In this paper, we extend the statistics to accommodate the possible within-paired correlation and within-clustered correlation, respectively. We use simulation studies to present comparative results. Finally, we illustrate the implementation of these methods using two real data sets. PMID:29456280

A versatile test for equality of two survival functions based on weighted differences of Kaplan-Meier curves.

Science.gov (United States)

Uno, Hajime; Tian, Lu; Claggett, Brian; Wei, L J

2015-12-10

With censored event time observations, the logrank test is the most popular tool for testing the equality of two underlying survival distributions. Although this test is asymptotically distribution free, it may not be powerful when the proportional hazards assumption is violated. Various other novel testing procedures have been proposed, which generally are derived by assuming a class of specific alternative hypotheses with respect to the hazard functions. The test considered by Pepe and Fleming (1989) is based on a linear combination of weighted differences of the two Kaplan-Meier curves over time and is a natural tool to assess the difference of two survival functions directly. In this article, we take a similar approach but choose weights that are proportional to the observed standardized difference of the estimated survival curves at each time point. The new proposal automatically makes weighting adjustments empirically. The new test statistic is aimed at a one-sided general alternative hypothesis and is distributed with a short right tail under the null hypothesis but with a heavy tail under the alternative. The results from extensive numerical studies demonstrate that the new procedure performs well under various general alternatives with a caution of a minor inflation of the type I error rate when the sample size is small or the number of observed events is small. The survival data from a recent cancer comparative study are utilized for illustrating the implementation of the process. Copyright © 2015 John Wiley & Sons, Ltd.

Test of equal effect per fraction and estimation of initial clonogen number in microcolony assays of survival after fractionated irradiation

International Nuclear Information System (INIS)

Thames, H.D.; Withers, H.R.

1980-01-01

In the use of multifraction microcolony assays to infer the low-dose response of in situ renewal systems such as intestinal crypts, the assumption of equal effect per dose fraction is required. Moreover, the construction of a cell-survival curve requires knowledge of the initial count of cells capable of repopulating each renewal structure. We describe a method of designing fractionation protocols which provides a regression estimate of the initial number of clonogens per renewal structure and a test of the hypothesis of equal effect per fraction. The essential factor in the experimental design is the use of common dose fractions (use of the same dose per fraction in series with different numbers of fractions). Applications of the method to data for which the assumption of equal effect per fraction holds (four-hour fractionation interval murine testis study) and does not hold (one-hour fractionation interval murine jejunal crypt study) are presented. (author)

Tests of equal effect per fraction in microcolony assays of survival after fractionated irradiations

International Nuclear Information System (INIS)

Taylor, J.M.G.

1985-01-01

H.D Thames, Jr. and H.R. Withers propose a test of an equal effect per fraction in microcolony assays after fractionated radiation, in which the total effect is measured by counting microcolonies derived from surviving cells in a tissue. The factors considered to influence the cytocidal effect per fraction are incomplete repair, repopulation, and synchrony. The statistics used in the method are criticized and conditions are given under which the test should not be used. An alternative method of testing for an equal effect per fraction is proposed. The pros and cons of each test are discussed and compared using some mouse jejunal crypt cell survival data

Survival of mouse testicular stem cells after γ or neutron irradiation

International Nuclear Information System (INIS)

Lu, C.C.; Meistrich, M.L.; Thames, H.D. Jr.

1980-01-01

The survival of mouse testicular stem cells after γ or neutron irradiation was measured by counts of repopulated tubular cross sections and by the numbers of differentiated spermatogenic cells produced. The numbers of such cells were determined either by sperm head counts of the X-isozyme of lactate dehydrogenase enzyme levels. Qualitatively similar results were obtained with all three assays. The results have confirmed that, with C3H mice, stem-cell survival is higher when the γ-radiation dose is fractionated by a 24-h interval. Single-dose γ-radiaton survival curves for the stem cell had large shoulders and also showed the presence of a radioresistant subpopulation which predominated after doses greater than 600 rad. Part of the shoulder must have resulted from repair of sublethal damage since neutron irradiation produced survival curves with smaller shoulders. The relative biological effectiveness for stem-cell killing for these neutrons (mean energy, 22 MeV) varied from about 2.9 at 10 rad of γ radiation to 2.2 at 600 rad

Survival curves to support quality improvement in hospitals with excess 30-day mortality after acute myocardial infarction, cerebral stroke and hip fracture: a before-after study.

Science.gov (United States)

Kristoffersen, Doris Tove; Helgeland, Jon; Waage, Halfrid Persdatter; Thalamus, Jacob; Clemens, Dirk; Lindman, Anja Schou; Rygh, Liv Helen; Tjomsland, Ole

2015-03-25

To evaluate survival curves (Kaplan-Meier) as a means of identifying areas in the clinical pathway amenable to quality improvement. Observational before-after study. In Norway, annual public reporting of nationwide 30-day in-and-out-of-hospital mortality (30D) for three medical conditions started in 2011: first time acute myocardial infarction (AMI), stroke and hip fracture; reported for 2009. 12 of 61 hospitals had statistically significant lower/higher mortality compared with the hospital mean. Three hospitals with significantly higher mortality requested detailed analyses for quality improvement purposes: Telemark Hospital Trust Skien (AMI and stroke), Østfold Hospital Trust Fredrikstad (stroke), Innlandet Hospital Trust Gjøvik (hip fracture). Survival curves, crude and risk-adjusted 30D before (2008-2009) and after (2012-2013). Unadjusted survival curves for the outlier hospitals were compared to curves based on pooled data from the other hospitals for the 30-day period 2008-2009. For patients admitted with AMI (Skien), stroke (Fredrikstad) and hip fracture (Gjøvik), the curves suggested increased mortality from the initial part of the clinical pathway. For stroke (Skien), increased mortality appeared after about 8 days. The curve profiles were thought to reflect suboptimal care in various phases in the clinical pathway. This informed improvement efforts. For 2008-2009, hospital-specific curves differed from other hospitals: borderline significant for AMI (p=0.064), highly significant (p≤0.005) for the remainder. After intervention, no difference was found (p>0.188). Before-after comparison of the curves within each hospital revealed a significant change for Fredrikstad (p=0.006). For the three hospitals, crude 30D declined and they were non-outliers for risk-adjusted 30D for 2013. Survival curves as a supplement to 30D may be useful for identifying suboptimal care in the clinical pathway, and thus informing design of quality improvement projects

Radiobiological effects of tritiated water short-term exposure on V79 clonogenic cell survival

DEFF Research Database (Denmark)

Siragusa, Mattia; Fredericia, Nina Pil Møntegaard; Jensen, Mikael

2018-01-01

We set out to improve the accuracy of absorbed dose calculations for in-vitro measurements of the Relative Biological Effectiveness (RBE) of tritiated water (HTO) for the clonogenic cell survival assay, also considering the influence of the end-of-track Linear Energy Transfer (LET) of low-energy...... in suspension are usually comparable to those for adherent cells. RBEs calculated at the 10% survival fraction through the use of the average energy are almost similar to those obtained with the beta-spectrum. For adherent cells, an RBE of 1.6 was found when HTO cell survival curves were compared to acute γ...

Parathyroid carcinoma survival: improvements in the era of intact parathyroid hormone monitoring?

Directory of Open Access Journals (Sweden)

Steve R. Martinez

2013-02-01

Full Text Available The intact parathyroid hormone (iPTH assay is a critical test in the diagnosis and management of PTH-mediated hypercalcemia, including parathyroid carcinoma (PCa. We hypothesized that the survival of patients diagnosed with PCa has improved since adoption of the iPTH assay into clinical practice. We identified all confirmed cases of PCa within the Surveillance, Epidemiology and End Results database from 1973 to 2006. Patients were categorized into two eras based upon introduction of the iPTH assay: 1973 to 1997 (era I and 1997 to 2006 (era II, when the iPTH assay was in standard use. We estimated overall survival (OS and disease-specific survival (DSS using the Kaplan-Meier method, with differences among survival curves assessed via log rank. Multivariate Cox proportional hazards models compared the survival rates between treatment eras while controlling for patient age, sex, race/ethnicity, tumor size, nodal status, extent of disease, and type of surgery. Multivariate models included patients undergoing potentially curative surgery and excluded those with dis- tant metastases. Risks of overall and disease-specific mortality were reported as hazard ratios with 95% confidence intervals. Study criteria were met by 370 patients. Median survival was 15.6 years. Five-year rates of OS and DSS were 78% and 88% for era I and 82% and 96% for era II. On multivariate analysis, age, black race, and unknown extent of disease predicted an increased risk of death from any cause. Treatment era did not predict OS. No factor predicted PCa-specific mortality. In multivariate analysis, neither OS nor DSS have improved in the current era that utilizes iPTH for the detection and management of PCa.

Initial slope of human tumor cell survival curves: its modification by the oxic cell sensitizer beta-arabinofuranosyladenine

International Nuclear Information System (INIS)

Chavaudra, N.; Halimi, M.; Parmentier, C.; Gaillard, N.; Grinfeld, S.; Malaise, E.P.

1989-01-01

The initial slope of the survival curve, which is a characteristic of each tumor cell line, varies with the histological group of the tumor. It is one of the factors on which clinical radioresponsiveness depends. The DNA dependant DNA polymerase inhibitor beta-ara A acts as an oxic cell sensitizer. This study was carried out on human tumor cell lines to look for a correlation between the degree of radiosensitization induced by beta-ara A and the radiosensitivity of a given cell line. Six human tumor cell lines with different radiosensitivities were used (the survival rate at 2 Gy and D ranged from 20 to 73% and from 1.2 to 3.2 Gy, respectively). beta-ara A had a major toxic effect on all cell lines but this varied greatly from one cell line to another and was concentration dependant; this toxic effect was taken into account when calculating the surviving fractions. For all cell lines, beta-ara A acted as an oxic radiosensitizer and the radiosensitization was concentration dependant. Analysis of the survival curves of the 6 cell lines using the linear quadratic model showed that concentrations of beta-ara A between 200 and 1000 microM induced an increase in the linear component while the quadratic component underwent no systematic change. The sensitizing enhancement ratio (SER) measured from the Ds ratios, varied greatly from one line to another. For example, at a concentration of 500 microM, the extreme values of Ds ratios were 1.5 and 2.6. The radiosensitization is greater, the higher the radiosensitivity of the cell line studied during exponential growth. The results do not favor the use of beta-ara A in the treatment of intrinsically radioresistant human tumors

Initial slope of human tumor cell survival curves: its modification by the oxic cell sensitizer beta-arabinofuranosyladenine

Energy Technology Data Exchange (ETDEWEB)

Chavaudra, N.; Halimi, M.; Parmentier, C.; Gaillard, N.; Grinfeld, S.; Malaise, E.P.

1989-05-01

The initial slope of the survival curve, which is a characteristic of each tumor cell line, varies with the histological group of the tumor. It is one of the factors on which clinical radioresponsiveness depends. The DNA dependant DNA polymerase inhibitor beta-ara A acts as an oxic cell sensitizer. This study was carried out on human tumor cell lines to look for a correlation between the degree of radiosensitization induced by beta-ara A and the radiosensitivity of a given cell line. Six human tumor cell lines with different radiosensitivities were used (the survival rate at 2 Gy and D ranged from 20 to 73% and from 1.2 to 3.2 Gy, respectively). beta-ara A had a major toxic effect on all cell lines but this varied greatly from one cell line to another and was concentration dependant; this toxic effect was taken into account when calculating the surviving fractions. For all cell lines, beta-ara A acted as an oxic radiosensitizer and the radiosensitization was concentration dependant. Analysis of the survival curves of the 6 cell lines using the linear quadratic model showed that concentrations of beta-ara A between 200 and 1000 microM induced an increase in the linear component while the quadratic component underwent no systematic change. The sensitizing enhancement ratio (SER) measured from the Ds ratios, varied greatly from one line to another. For example, at a concentration of 500 microM, the extreme values of Ds ratios were 1.5 and 2.6. The radiosensitization is greater, the higher the radiosensitivity of the cell line studied during exponential growth. The results do not favor the use of beta-ara A in the treatment of intrinsically radioresistant human tumors.

Establishment of 60Co dose calibration curve using fluorescent in situ hybridization assay technique: Result of preliminary study

International Nuclear Information System (INIS)

Rahimah Abdul Rahim; Noriah Jamal; Noraisyah Mohd Yusof; Juliana Mahamad Napiah; Nelly Bo Nai Lee

2010-01-01

This study aims at establishing an in-vitro 60 Co dose calibration curve using Fluorescent In-Situ Hybridization assay technique for the Malaysian National Bio dosimetry Laboratory. Blood samples collected from a female healthy donor were irradiated with several doses of 60 Co radiation. Following culturing of lymphocytes, microscopic slides are prepared, denatured and hybridized. The frequencies of translocation are estimated in the metaphases. A calibration curve was then generated using a regression technique. It shows a good fit to a linear-quadratic model. The results of this study might be useful in estimating absorbed dose for the individual exposed to ionizing radiation retrospectively. This information may be useful as a guide for medical treatment for the assessment of possible health consequences. (author)

Radiosensitivity of CD4 and CD8 positive human T lymphocytes by an in vitro colony formation assay

International Nuclear Information System (INIS)

Nakamura, Nori; Kusunoki, Yoichiro; Akiyama, Mitoshi.

1989-12-01

The recent development of an in vitro lymphocyte colony assay provides a new opportunity to examine possible variations in human radiosensitivity using peripheral blood lymphocytes (PBL) in place of the hitherto used skin fibroblast assay. Our recent study showed that most of the colonies consisted of lymphocytes bearing CD4 or CD8 antigens. Since the fraction of CD4 + and CD8 + cells in PBL differs among individuals, it was suspected that individual radiosensitivity might be biased by the different subset frequencies if the dose-survival curves of the CD4 + and CD8 + cells differed. In the present study, CD4 + lymphocytes (helper/inducer T cells) and CD8 + lymphocytes (suppressor/cytotoxic T cells) were isolated from PBL and their dose-survival curves were determined. The results showed that the D 10 (the dose required to reduce the surviving fraction to 10 %) was quite similar for these two types of cells (3.13 ± 0.10 Gy [mean ±SD] for CD4 + , 3.34 ± 0.50 Gy for CD8 + and 3.07 ± 0.05 Gy for the unsorted cells), supporting the use of a whole PBL population for screening of individuals with altered radiosensitivity. (author)

Implications of the quadratic cell survival curve and human skin radiation ''tolerance doses'' on fractionation and superfractionation dose selection

International Nuclear Information System (INIS)

Douglas, B.G.

1982-01-01

An analysis of early published multifraction orthovoltage human acute skin irradiation tolerance isoeffect doses is presented. It indicates that human acute skin radiation reactions may result from the repetition, with each dose fraction, of a cell survival curve of the form: S = e/sup -(αD + βD 2 )/). The analysis also shows no need for an independent proliferation related time factor for skin, for daily treatments of six weeks or less in duration. The value obtained for the constant β/α for orthovoltage irradiation from these data is 2.9 x 10 -3 rad -1 for the cell line determining acute skin tolerance. A radiation isoeffect relationship, based on the quadratic cell survival curve, is introduced for human skin. This relationship has some advantages over the nominal standard dose (NSD). First, its use is not restricted to tolerance level reactions. Second, a modification of the relationship, which is also introduced, may be employed in the selection of doses per treatment when irradiation dose fractions are administered at short intervals where repair of sublethal injury is incomplete

Rat mammary-cell survival following irradiation with 14.3-MeV neutrons

International Nuclear Information System (INIS)

Mahler, P.A.; Gould, M.N.; DeLuca, P.M. Jr.; Pearson, D.W.; Clifton, K.H.

1982-01-01

The survival of rat mammary gland cells irradiated in situ with either single or split doses of 14.3-MeV neutrons was determined by an in vivo transplantation assay. The single-dose data are best fit to the multitarget single-hit model by the parameters D 0 = 97 cGy and n = 0.6 while the split-dose data are best fit by the parameters D 0 = 100 cGy and n = 1.2. Analysis of the combined data sets suggests that the two survival curves are not identical. Comparison of these data with previously published results following irradiation with 250-kVp x-rays is reported

Rat mammary cell survival following irradiation with 14.3-MeV neutrons

International Nuclear Information System (INIS)

Mahler, P.A.; Gould, M.N.; DeLuca, P.M. Jr.; Pearson, D.W.; Clifton, K.H.

1982-01-01

The survival of rat mammary gland cells irradiated in situ with either single or split doses of 14.3-MeV neutrons was determined by an in vivo transplantation assay. The single-dose data are best fit to the multitarget single-hit model by the parameters D/sub o/ = 97 cGy and n = 0.6 while the split-dose data are best fit by the parameters D/sub o/ = 100 cGy and n = 1.2.Analysis of the combined data sets suggests that the two survival curves are not identical. Comparison of these data with previously published results following irradiation with 250-kVp X rays is reported

Comparing survival curves using rank tests

NARCIS (Netherlands)

Albers, Willem/Wim

1990-01-01

Survival times of patients can be compared using rank tests in various experimental setups, including the two-sample case and the case of paired data. Attention is focussed on two frequently occurring complications in medical applications: censoring and tail alternatives. A review is given of the

In vitro chemo-sensitivity assay guided chemotherapy is associated with prolonged overall survival in cancer patients.

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Udelnow, Andrej; Schönfęlder, Manfred; Würl, Peter; Halloul, Zuhir; Meyer, Frank; Lippert, Hans; Mroczkowski, Paweł

2013-06-01

The overall survival (OS) of patients suffering From various tumour entities was correlated with the results of in vitro-chemosensitivity assay (CSA) of the in vivo applied drugs. Tumour specimen (n=611) were dissected in 514 patients and incubated for primary tumour cell culture. The histocytological regression assay was performed 5 days after adding chemotherapeutic substances to the cell cultures. n=329 patients undergoing chemotherapy were included in the in vitro/in vivo associations. OS was assessed and in vitro response groups compared using survival analysis. Furthermore Cox-regression analysis was performed on OS including CSA, age, TNM classification and treatment course. The growth rate of the primary was 73-96% depending on tumour entity. The in-vitro response rate varied with histology and drugs (e.g. 8-18% for methotrexate and 33-83% for epirubicine). OS was significantly prolonged for patients treated with in vitro effective drugs compared to empiric therapy (log-rank-test, p=0.0435). Cox-regression revealed that application of in vitro effective drugs, residual tumour and postoperative radiotherapy determined the death risk independently. When patients were treated with drugs effective in our CSA, OS was significantly prolonged compared to empiric therapy. CSA guided chemotherapy should be compared to empiric treatment by a prospective randomized trial.

Usefulness of antigen-specific IgE probability curves derived from the 3gAllergy assay in diagnosing egg, cow's milk, and wheat allergies

Directory of Open Access Journals (Sweden)

Sakura Sato

2017-04-01

Conclusions: Measurements of sIgE against egg, milk, and wheat as determined by 3gAllergy may be used as a tool to facilitate the diagnosis of food allergy in subjects with suspected food allergies. However, these probability curves should not be applied interchangeably between different assays.

Stimulated human fibroblast cell survival

International Nuclear Information System (INIS)

Smith, B.P.; Gale, K.L.; Einspenner, M.; Greenstock, C.L.; Gentner, N.E.

1992-01-01

Techniques for cloning cultured mammalian cells have supported the most universally-accepted method for measuring the induction of lethality by geno-toxicants such as ionizing radiation: the 'survival of colony-forming ability (CFA)' assay. Since most cultured human cell lines exhibit plating efficiency (i.e. the percentage of cells that are capable of reproductively surviving and dividing to form visible colonies) well below 100%, such assays are in essence 'survival of plating efficiency' assays, since they are referred to the plating (or cloning) efficiency of control (i.e. unirradiated) cells. (author). 8 refs., 2 figs

A review and comparison of methods for recreating individual patient data from published Kaplan-Meier survival curves for economic evaluations: a simulation study.

Science.gov (United States)

Wan, Xiaomin; Peng, Liubao; Li, Yuanjian

2015-01-01

In general, the individual patient-level data (IPD) collected in clinical trials are not available to independent researchers to conduct economic evaluations; researchers only have access to published survival curves and summary statistics. Thus, methods that use published survival curves and summary statistics to reproduce statistics for economic evaluations are essential. Four methods have been identified: two traditional methods 1) least squares method, 2) graphical method; and two recently proposed methods by 3) Hoyle and Henley, 4) Guyot et al. The four methods were first individually reviewed and subsequently assessed regarding their abilities to estimate mean survival through a simulation study. A number of different scenarios were developed that comprised combinations of various sample sizes, censoring rates and parametric survival distributions. One thousand simulated survival datasets were generated for each scenario, and all methods were applied to actual IPD. The uncertainty in the estimate of mean survival time was also captured. All methods provided accurate estimates of the mean survival time when the sample size was 500 and a Weibull distribution was used. When the sample size was 100 and the Weibull distribution was used, the Guyot et al. method was almost as accurate as the Hoyle and Henley method; however, more biases were identified in the traditional methods. When a lognormal distribution was used, the Guyot et al. method generated noticeably less bias and a more accurate uncertainty compared with the Hoyle and Henley method. The traditional methods should not be preferred because of their remarkable overestimation. When the Weibull distribution was used for a fitted model, the Guyot et al. method was almost as accurate as the Hoyle and Henley method. However, if the lognormal distribution was used, the Guyot et al. method was less biased compared with the Hoyle and Henley method.

Genotyping of a tri-allelic polymorphism by a novel melting curve assay in MTHFD1L: an association study of nonsyndromic Cleft in Ireland

LENUS (Irish Health Repository)

Minguzzi, Stefano

2012-04-20

AbstractBackgroundPolymorphisms within the MTHFD1L gene were previously associated with risk of neural tube defects in Ireland. We sought to test the most significant MTHFD1L polymorphisms for an association with risk of cleft in an Irish cohort. This required the development of a new melting curve assay to genotype the technically challenging MTHFD1L triallelic deletion\\/insertion polymorphism (rs3832406).MethodsMelting curve analysis was used to genotype the MTHFD1L triallelic deletion\\/insertion polymorphism (rs3832406) and a Single Nucleotide Polymorphism rs17080476 in an Irish cohort consisting of 981 Irish case-parent trios and 1,008 controls. Tests for association with nonsyndromic cleft lip with or without cleft palate and cleft palate included case\\/control analysis, mother\\/control analysis and Transmission Disequilibrium Tests of case-parent trios.ResultsA successful melting curve genotyping assay was developed for the deletion\\/insertion polymorphism (rs3832406). The TDT analysis initially showed that the rs3832406 polymorphism was associated with isolated cleft lip with or without cleft palate. However, corrected p-values indicated that this association was not significant.ConclusionsMelting Curve Analysis can be employed to successfully genotype challenging polymorphisms such as the MTHFD1L triallelic deletion\\/insertion polymorphism (DIP) reported here (rs3832406) and is a viable alternative to capillary electrophoresis. Corrected p-values indicate no association between MTHFD1L and risk of cleft in an Irish cohort.

Radioreceptor opioid assay

International Nuclear Information System (INIS)

Miller, R.J.; Chang, K.-J.

1981-01-01

A radioreceptor assay is described for assaying opioid drugs in biological fluids. The method enables the assay of total opioid activity, being specific for opioids as a class but lacking specificity within the class. A radio-iodinated opioid and the liquid test sample are incubated with an opiate receptor material. The percentage inhibition of the binding of the radio-iodinated compound to the opiate receptor is calculated and the opioid activity of the test liquid determined from a standard curve. Examples of preparing radio-iodinated opioids and assaying opioid activity are given. A test kit for the assay is described. Compared to other methods, this assay is cheap, easy and rapid. (U.K.)

Immuno-oncology combinations: raising the tail of the survival curve

International Nuclear Information System (INIS)

Harris, Samuel J.; Brown, Jessica; Lopez, Juanita; Yap, Timothy A.

2016-01-01

There have been exponential gains in immuno-oncology in recent times through the development of immune checkpoint inhibitors. Already approved by the U.S. Food and Drug Administration for advanced melanoma and non-small cell lung cancer, immune checkpoint inhibitors also appear to have significant antitumor activity in multiple other tumor types. An exciting component of immunotherapy is the durability of antitumor responses observed, with some patients achieving disease control for many years. Nevertheless, not all patients benefit, and efforts should thus now focus on improving the efficacy of immunotherapy through the use of combination approaches and predictive biomarkers of response and resistance. There are multiple potential rational combinations using an immunotherapy backbone, including existing treatments such as radiotherapy, chemotherapy or molecularly targeted agents, as well as other immunotherapeutics. The aim of such antitumor strategies will be to raise the tail on the survival curve by increasing the number of long term survivors, while managing any additive or synergistic toxicities that may arise with immunotherapy combinations. Rational trial designs based on a clear understanding of tumor biology and drug pharmacology remain paramount. This article reviews the biology underpinning immuno-oncology, discusses existing and novel immunotherapeutic combinations currently in development, the challenges of predictive biomarkers of response and resistance and the impact of immuno-oncology on early phase clinical trial design

Does my high blood pressure improve your survival? Overall and subgroup learning curves in health.

Science.gov (United States)

Van Gestel, Raf; Müller, Tobias; Bosmans, Johan

2017-09-01

Learning curves in health are of interest for a wide range of medical disciplines, healthcare providers, and policy makers. In this paper, we distinguish between three types of learning when identifying overall learning curves: economies of scale, learning from cumulative experience, and human capital depreciation. In addition, we approach the question of how treating more patients with specific characteristics predicts provider performance. To soften collinearity problems, we explore the use of least absolute shrinkage and selection operator regression as a variable selection method and Theil-Goldberger mixed estimation to augment the available information. We use data from the Belgian Transcatheter Aorta Valve Implantation (TAVI) registry, containing information on the first 860 TAVI procedures in Belgium. We find that treating an additional TAVI patient is associated with an increase in the probability of 2-year survival by about 0.16%-points. For adverse events like renal failure and stroke, we find that an extra day between procedures is associated with an increase in the probability for these events by 0.12%-points and 0.07%-points, respectively. Furthermore, we find evidence for positive learning effects from physicians' experience with defibrillation, treating patients with hypertension, and the use of certain types of replacement valves during the TAVI procedure. Copyright © 2017 John Wiley & Sons, Ltd.

A novel microculture kinetic assay (MiCK assay) for malignant cell growth and chemosensitivity.

Science.gov (United States)

Kravtsov, V D

1994-01-01

The THERMOmax microplate reader was adapted for monitoring the growth kinetics of human leukaemic OCI/AML-2 and mouse tumour J-774.1 cell lines in continuous culture. Fluid evaporation from wells, CO2 escape and contamination were prevented by hermetic sealing of the microcultures in wells of a 96-well microplate, thus enabling the cells to grow exponentially for 72 h under the conditions of the incubated microplate reader. For both OCI/AML-2 cells, which grow in suspension, and adherent J-774.1 cells, a linear correlation was demonstrated between the number of unstained cells seeded in a given microplate well and the optical density (OD) of that well. Therefore, the OD/time curve of the culture could be deemed to be its growth curve. By the use of the linear fit equation, the actual number of the cells in the wells was computable at any time point of the assay. In the chemosensitivity test, an inhibitory effect of ARA-C on the growth of the cells could be estimated by viewing of the growth curves plotted on the screen. The maximum kinetic rates (Vmax) of the curves in the control and the ARA-C-treated wells were compared, yielding a growth inhibition index (GII). Comparison of results of the kinetic chemosensitivity assay with those of a [3H]thymidine incorporation assay revealed that the novel assay is suitable for precise quantitation of the cell chemosensitivity, is more informative and has the added technical advantage of performance without recourse to radioactive or chemically hazardous substances.

Usefulness of antigen-specific IgE probability curves derived from the 3gAllergy assay in diagnosing egg, cow's milk, and wheat allergies.

Science.gov (United States)

Sato, Sakura; Ogura, Kiyotake; Takahashi, Kyohei; Sato, Yasunori; Yanagida, Noriyuki; Ebisawa, Motohiro

2017-04-01

Specific IgE (sIgE) antibody detection using the Siemens IMMULITE ® 3gAllergy™ (3gAllergy) assay have not been sufficiently examined for the diagnosis of food allergy. The aim of this study was to evaluate the utility of measuring sIgE levels using the 3gAllergy assay to diagnose allergic reactions to egg, milk, and wheat. This retrospective study was conducted on patients with diagnosed or suspected allergies to egg, milk and wheat. Patients were divided into two groups according to their clinical reactivity to these allergens based on oral food challenge outcomes and/or convincing histories of immediate reaction to causative food(s). The sIgE levels were measured using 3gAllergy and ImmunoCAP. Predicted probability curves were estimated using logistic regression analysis. We analyzed 1561 patients, ages 0-19 y (egg = 436, milk = 499, wheat = 626). The sIgE levels determined using 3gAllergy correlated with those of ImmunoCAP, classifying 355 patients as symptomatic: egg = 149, milk = 123, wheat = 83. 3gAllergy sIgE levels were significantly higher in symptomatic than in asymptomatic patients (P allergies. However, these probability curves should not be applied interchangeably between different assays. Copyright © 2016 Japanese Society of Allergology. Production and hosting by Elsevier B.V. All rights reserved.

Modification of survival and hematopoiesis in mice by tocopherol injection following irradiation

International Nuclear Information System (INIS)

Bichay, T.J.E.; Roy, R.M.

1986-01-01

The LD 50/30 of CD-1-female mice increased from 6.6 Gy to 7.0 Gy when 2.5 mg of dl-α-tocopherol was injected immediately post irradiation. Increased survival was associated with increased numbers of hematopoietic colony forming units (CFU). Endogeneous spleen colonies were found in greater numbers in the tocopherol-treated mice after irradiation. The vitamin, however, must be injected within five hours following irradiation to have this effect. The increased numbers of CFU in tocopherol-treated mice may be due to a stimulation of recovery of repair processes. Split-dose studies suggest that most repair of sublethal damage in hematopoietic stem cells take place within seven and nine hours following irradiation. Tocopherol injection appears to enhance the recovery manifested in the split-dose assay. There is also evidence that tocopherol-treatment caused an earlier onset of mitotic activity in CFU after irradiation. The increased number of spleen colonies in tocopherol-injected mice is not due to an altered CFU seeding efficiency associated with an altered spleen microenvironment. Tocopherol injection did not affect the shoulder of the stem cell survival curve using exogenous spleen colony assays of bone marrow-derived or spleen-derived hematopoietic stem cells. There appears to be a decrease in D 0 in the higher dose region (4.3 Gy) of the bone marrow exogenous SCA survival curves for the vehicle-injected and the non-injected groups; however, the tocopherol-injected group showed no evidence of change in radiosensitivity up to the highest dose used (5.0 Gy). Data may be interpreted to suggest that the therapeutic effect of tocopherol may involve repair of hematopoietic stem cell damage in the higher dose range of bone marrow syndrome. (orig.) [de

The effect on the small bowel of 5-FU and oxaliplatin in combination with radiation using a microcolony survival assay

Directory of Open Access Journals (Sweden)

Kjellén Elisabeth

2009-12-01

Full Text Available Abstract Background In locally advanced rectal cancer, 5-Fluorouracil (5-FU-based chemoradiation is the standard treatment. The main acute toxicity of this treatment is enteritis. Due to its potential radiosensitizing properties, oxaliplatin has recently been incorporated in many clinical chemoradiation protocols. The aim of this study was to investigate to what extent 5-FU and oxaliplatin influence the radiation (RT induced small bowel mucosal damage when given in conjunction with single or split dose RT. Methods Immune competent balb-c mice were treated with varying doses of 5-FU, oxaliplatin (given intraperitoneally and total body RT, alone or in different combinations in a series of experiments. The small bowel damage was studied by a microcolony survival assay. The treatment effect was evaluated using the inverse of the slope (D0 of the exponential part of the dose-response curve. Results In two separate experiments the dose-response relations were determined for single doses of RT alone, yielding D0 values of 2.79 Gy (95% CI: 2.65 - 2.95 and 2.98 Gy (2.66 - 3.39, for doses in the intervals of 5-17 Gy and 5-10 Gy, respectively. Equitoxic low doses (IC5 of the two drugs in combination with RT caused a decrease in jejunal crypt count with significantly lower D0: 2.30 Gy (2.10 - 2.56 for RT+5-FU and 2.27 Gy (2.08 - 2.49 for RT+oxaliplatin. Adding both drugs to RT did not further decrease D0: 2.28 Gy (1.97 - 2.71 for RT+5-FU+oxaliplatin. A clearly higher crypt survival was noted for split course radiation (3 × 2.5 Gy compared to a single fraction of 7.5 Gy. The same difference was seen when 5-FU and/or oxaliplatin were added. Conclusion Combining 5-FU or oxaliplatin with RT lead to an increase in mucosal damage as compared to RT alone in our experimental setting. No additional reduction of jejunal crypt counts was noted when both drugs were combined with single dose RT. The higher crypt survival with split dose radiation indicates a

Ultrasensitive prostate specific antigen assay following laparoscopic radical prostatectomy--an outcome measure for defining the learning curve.

Science.gov (United States)

Viney, R; Gommersall, L; Zeif, J; Hayne, D; Shah, Z H; Doherty, A

2009-07-01

Radical retropubic prostatectomy (RRP) performed laparoscopically is a popular treatment with curative intent for organ-confined prostate cancer. After surgery, prostate specific antigen (PSA) levels drop to low levels which can be measured with ultrasensitive assays. This has been described in the literature for open RRP but not for laparoscopic RRP. This paper describes PSA changes in the first 300 consecutive patients undergoing non-robotic laparoscopic RRP by a single surgeon. To use ultrasensitive PSA (uPSA) assays to measure a PSA nadir in patients having laparoscopic radical prostatectomy below levels recorded by standard assays. The aim was to use uPSA nadir at 3 months' post-prostatectomy as an early surrogate end-point of oncological outcome. In so doing, laparoscopic oncological outcomes could then be compared with published results from other open radical prostatectomy series with similar end-points. Furthermore, this end-point could be used in the assessment of the surgeon's learning curve. Prospective, comprehensive, demographic, clinical, biochemical and operative data were collected from all patients undergoing non-robotic laparoscopic RRP. We present data from the first 300 consecutive patients undergoing laparoscopic RRP by a single surgeon. uPSA was measured every 3 months post surgery. Median follow-up was 29 months (minimum 3 months). The likelihood of reaching a uPSA of bench-marking performance. With experience, a surgeon can achieve in excess of an 80% chance of obtaining a uPSA nadir of < or = 0.01 ng/ml at 3 months after laparoscopic RRP for a British population. This is equivalent to most published open series.

Modification by preirradiation growth conditions of the shoulder of the UV fluence-survival curve of Escherichia coli B/r WP2 thy trp and changes in mutagenic response toward tryptophan prototrophy

International Nuclear Information System (INIS)

Doudney, C.O.

1978-01-01

The distinct three-section UV fluence-mutation frequency response (MFR) curve demonstrated in Escherichia coli strain B/r WP2 thy trp and its uvrA derivative supports the SOS hypothesis and suggests that trp + revertants can arise either from isolated lesions (1DM) plus SOS induction or from two lesions in proximity (2DM). Preirradiation growth on arabinose instead of glucose converted the fluence-survival curve from highly shouldered to exponential but did not affect the three-section MFR curve. Prestarvation of the uvrA + strain for typtophan, which drastically increases the expanse of the shoulder of the survival curve, greatly decreased both 1DM and 2DM. With the uvrA strain the increase in shoulder expanse after typtophan prestarvation was accompanied by greatly increased 2DM but no change in 1DM. Preincubation with chloramphenicol induced an even greater increase in 2DM response than amino acid prestarvation. Nalidixic acid, which prevents DNA accumulation, eliminated the response. (Auth.)

Multiplex real-time PCR assays for detection of eight Shiga toxin-producing Escherichia coli in food samples by melting curve analysis.

Science.gov (United States)

Singh, Prashant; Mustapha, Azlin

2015-12-23

Shiga toxin-producing Escherichia coli (STEC) are pathogenic strains of E. coli that can cause bloody diarrhea and kidney failure. Seven STEC serogroups, O157, O26, O45, O103, O111, O121 and O145 are responsible for more than 71% of the total infections caused by this group of pathogens. All seven serogroups are currently considered as adulterants in non-intact beef products in the U.S. In this study, two multiplex melt curve real-time PCR assays with internal amplification controls (IACs) were standardized for the detection of eight STEC serogroups. The first multiplex assay targeted E. coli serogroups O145, O121, O104, and O157; while the second set detected E. coli serogroups O26, O45, O103 and O111. The applicability of the assays was tested using 11 different meat and produce samples. For food samples spiked with a cocktail of four STEC serogroups with a combined count of 10 CFU/25 g food, all targets of the multiplex assays were detected after an enrichment period of 6h. The assays also worked efficiently when 325 g of food samples were spiked with 10 CFU of STECs. The assays are not dependent on fluorescent-labeled probes or immunomagnetic beads, and can be used for the detection of eight STEC serogroups in less than 11h. Routine preliminary screening of STECs in food samples is performed by testing for the presence of STEC virulence genes. The assays developed in this study can be useful as a first- or second-tier test for the identification of the eight O serogroup-specific genes in suspected food samples. Copyright © 2015. Published by Elsevier B.V.

Relationship between lung colony and in situ assays

International Nuclear Information System (INIS)

Ando, K.; Koike, S.

1985-01-01

The relationship between different assays: tumor control, tumor growth delay and lung colony formation was examined after fast neutron and γ ray irradiations. Fibrosarcomas (NFSa) in syngeneic C3Hf mice were irradiated locally with 60 Co γ rays, fast neutrons or mixed beams (γ rays and fast neutrons). A comparison between the lung colony assay and the TRT 50 (50% tumor growth delay time) assay when cells were exposed to single doses of fast neutrons or γ rays, resulted in identical growth delay times. The fraction of cells surviving a single dose of fast neutrons, was 10 times higher than the surviving fraction of cells after a single dose of γ rays. Both doses resulted in the same tumor control probability (TCD 50 assay). Neither repair of potentially lethal damage nor tumor bed effect was sufficient to explain the difference between cell survival and tumor control probability. The surviving fraction of cells following fractionated irradiations of γ rays and fast neutrons were identical at 50% tumor control probabilities

Neutron and photon clonogenic survival curves of two chemotherapy resistant human intermediate-grade non-Hodgkin lymphoma cell lines

International Nuclear Information System (INIS)

Aref, Amr; Yudelev, Mark; Mohammad, Ramzi; Choudhuri, Rajani; Orton, Colin; Al-Katib, Ayad

1999-01-01

Background: The potential role of neutron therapy in the management of intermediate-grade non-Hodgkin lymphoma (IGNHL) has not been examined because of the belief that the anticipated radiobiological effectiveness (RBE) would be uniformly very low. Purpose: To determine the fast neutron RBE for two chemotherapy-resistant IGNHL cell lines. Methods and Materials: Conventional soft agar clonogenic survival curves following irradiation by 60 Co and fast neutron were established for two IGNHL cell lines. These cell lines, WSU-DLCL2 and SK-DHL2B, were found in previous studies to be able to repair sublethal damage, and were also resistant to L-Pam and doxorubicin chemotherapy. Results: When the surviving fraction after 2 Gy photon was chosen as the biological endpoint, the RBE for WSU-DLCL2 and SK-DHL2B measured 3.34 and 3.06. Similarly, when 10% survival was considered, the RBE for these two cell lines measured 2.54 and 2.59. The RBE, as measured by the ratios α neutron/α photon, for WSU-DLCL2, SK-DHL2B cell lines are 6.67 and 5.65, respectively. These results indicate that the RBE for these IGNHL cell lines is higher than the average RBE for cell lines of other histological types. Conclusion: Fast neutron irradiation may be of potential value in treating selected cases of IGNHL

Construction of dose-effect curves by irradiating peripheral blood mononuclear cells analyzed with the alkaline comet assay

International Nuclear Information System (INIS)

Rueda, Lenin; Rosales Jaime; Leon, Kety; Espinoza, Marco

2015-01-01

The suitability of the alkaline comet assay to detect levels of DNA damage in human monocytes and lymphocytes under radiation was tested. For this purpose, four dose-effect curves by irradiation of cells isolated from blood samples of 4 young, health and non-smoker donors. A gamma ray source of "6"0Co was used and doses of 0, 2.5, 5 and 7 Gy were delivered to blood cells. The results show good correlation (R2 = 0.973, SD = 0.009) between the radiation dose and DNA damage as measured by the parameter Tail Intensity (percentage of DNA in the tail of the 'comet'). Furthermore, we observe the variability in predicting DNA damage by Gy (7.59, SD = 1.5). Potential use of this technique in the biological dosimetry of ionizing radiations is being evaluated. (author)

Area-under-the-curve monitoring of cyclosporine therapy: Performance of different assay methods and their target concentrations

International Nuclear Information System (INIS)

Grevel, J.; Napoli, K.L.; Gibbons, S.; Kahan, B.D.

1990-01-01

The measurement of areas under the concentration-time curve (AUC) was recently introduced as an alternative to trough level monitoring of cyclosporine therapy. The AUC is divided by the oral dosing interval to calculate an average concentration. All measurements are performed at clinical steady state. The initial evaluation of AUC monitoring showed advantages over trough level monitoring with concentrations of cyclosporine measured in serum by the polyclonal radioimmunoassay of Sandoz. This assay technique is no longer available and the following assays were performed in parallel during up to 173 AUC determinations in 51 consecutive renal transplant patients: polyclonal fluorescence polarization immunoassay of Abbott in serum, specific and nonspecific monoclonal radioimmunoassays using 3 H and 125 I tracers in serum and whole blood, and high performance liquid chromatography in whole blood. Both trough levels and average concentrations at steady state measured by those different techniques were significantly correlated with the oral dose. The best correlation (r2 = 0.54) was shown by average concentrations measured in whole blood by the specific monoclonal radioimmunoassay of Sandoz ( 3 H tracer). This monitoring technique was also associated with the smallest absolute error between repeated observations in the same patient while the oral dose rate remained the same or was changed. Both allegedly specific monoclonal radioimmunoassays (with 3 H and 125 I tracer) measured significantly higher concentrations than the liquid chromatography

Assessing Clinical Outcomes in Colorectal Cancer with Assays for Invasive Circulating Tumor Cells.

Science.gov (United States)

Zhang, Yue; Zarrabi, Kevin; Hou, Wei; Madajewicz, Stefan; Choi, Minsig; Zucker, Stanley; Chen, Wen-Tien

2018-06-06

Colorectal carcinoma (CRC) is the second leading cause of cancer-related mortality. The goals of this study are to evaluate the association between levels of invasive circulating tumor cells (iCTCs) with CRC outcomes and to explore the molecular characteristics of iCTCs. Peripheral blood from 93 patients with Stage I⁻IV CRC was obtained and assessed for the detection and characterization of iCTCs using a functional collagen-based adhesion matrix (CAM) invasion assay. Patients were followed and assessed for overall survival. Tumor cells isolated by CAM were characterized using cell culture and microarray analyses. Of 93 patients, 88 (95%) had detectable iCTCs, ranging over 0⁻470 iCTCs/mL. Patients with Stage I⁻IV disease exhibited median counts of 0.0 iCTCs/mL ( n = 6), 13.0 iCTCs/mL ( n = 12), 41.0 iCTCs/mL ( n = 12), and 133.0 iCTCs/mL ( n = 58), respectively ( p < 0.001). Kaplan⁻Meier curve analysis demonstrated a significant survival benefit in patients with low iCTC counts compared with in patients with high iCTC counts (log-rank p < 0.001). Multivariable Cox model analysis revealed that iCTC count was an independent prognostic factor of overall survival ( p = 0.009). Disease stage ( p = 0.01, hazard ratio 1.66; 95% confidence interval: 1.12⁻2.47) and surgical intervention ( p = 0.03, HR 0.37; 95% CI: 0.15⁻0.92) were also independent prognostic factors. Gene expression analysis demonstrated the expression of both endothelial and tumor progenitor cell biomarkers in iCTCs. CAM-based invasion assay shows a high detection sensitivity of iCTCs that inversely correlated with overall survival in CRC patients. Functional and gene expression analyses showed the phenotypic mosaics of iCTCs, mimicking the survival capability of circulating endothelial cells in the blood stream.

Depression and Liver Transplant Survival.

Science.gov (United States)

Meller, William; Welle, Nicole; Sutley, Kristen; Thurber, Steven

Patients who underwent liver transplantation and experienced clinical depression have heretofore evinced lower survival rates when compared to nondepressed counterparts. To investigate the hypothesis that transplant patients who seek and obtain medical treatment for depression would circumvent the prior reduced survival findings. A total of 765 patients with liver transplants were scrutinized for complications following transplantation. Further, 104 patients experienced posttransplant depression as manifested by diagnosis and treatment by medical personnel. Survival analyses were conducted comparing hazard and survival curves for these selected individuals and the remainder of transplant patients. Contrary to prior data and consistent with the aforementioned hypothesis, median survival durations, survival curves, and hazard functions (controlling for age and prolonged posttransplant survival for the depressed patients were better. The improved survival for the depressed patients may simply be related to an amelioration of depressed symptoms via antidepressant medications. However, this interpretation would only be congruent with reduced hazard, not elevated survival, beyond the norm (median) for other transplant participants. Assuming the reliability and generalization of our findings, perhaps a reasonable and compelling interpretation is that combined with the effectiveness of antidepressant medications, the seeking and receiving treatment for depression is a type of proxy measure of a more global pattern of adherence to recommended posttransplant medical regimens. Copyright © 2017 The Academy of Psychosomatic Medicine. Published by Elsevier Inc. All rights reserved.

Survival patterns and hemopathological responses of dogs under continuous gamma irradiation

International Nuclear Information System (INIS)

Seed, T.M.; Fritz, T.E.; Tolle, D.V.; Poole, C.M.; Lombard, L.S.; Doyle, D.E.; Kaspar, L.V.; Cullen, S.M.; Carnes, B.A.

1983-01-01

Survival curves were constructed and analyzed relative to contributing hematopathological responses for groups of beagles exposed continuously for duration of life to low daily doses of whole body 60 Co gamma irradiation (27.3 rads/day to 4 rads/day). The survival curves versus time were progressively displaced toward longer survival as rates of exposure were reduced from the relatively high dose rate of 27.3 rads/day to the low dose rate of 4.0 rads/day. Average survival times increased from 57 days at 27.3 rads/day to 1830 days at 4.0 rads/day, representing fractional increased life-spans from 1.5% to 50.8%, respectively. Survival curves versus total dose were markedly displaced along the cumulative radiation dose axis at the extreme dose rates (i.e., 27.3 and 4.0 rads/day), but not at the intermediate dose rates (i.e., 13.4 and 7.9 rads/day) in which the upper linear portions of the survival curves are superimposed. From these dose-dependent survival curves, LD 50 values for whole body gamma irradiation, delivered chronically at 27.3, 13.4, 7.9, and 4.0 rads per day were estimated to be 1442, 2124, 2039, and 7161 rads, respectively. Both time- and dose-dependent survival curves for the intermediate dose rates, in contrast to the extreme dose rates, exhibited pronounced transitions in the lethality rate below the 50% survival level. These lethality rate transitions occurred at approx. 2500 rads of accumulated dose and were attributed to a shift in the spectrum of developing hematopathologies: namely, from a predominance of the acutely ablative radiation-induced lymphohematopoietic syndromes (i.e., septicemias and aplastic anemias) to a predominance of the late arising hematopoietic neoplasias (myelogenous leukemia and related myeloproliferative disorders)

Summary curves for patients transplanted for chronic myeloid leukaemia salvaged by a donor lymphocyte infusion: the current leukaemia-free survival curve

DEFF Research Database (Denmark)

Klein, John P.; Keiding, Niels; Shu, Youyi

2000-01-01

CML, donor lymphocyte infusion, leukaemia-free survival, current leukaemia-free survival, statistical methods......CML, donor lymphocyte infusion, leukaemia-free survival, current leukaemia-free survival, statistical methods...

Detection of Babesia canis vogeli and Hepatozoon canis in canine blood by a single-tube real-time fluorescence resonance energy transfer polymerase chain reaction assay and melting curve analysis.

Science.gov (United States)

Kongklieng, Amornmas; Intapan, Pewpan M; Boonmars, Thidarut; Thanchomnang, Tongjit; Janwan, Penchom; Sanpool, Oranuch; Lulitanond, Viraphong; Taweethavonsawat, Piyanan; Chungpivat, Sudchit; Maleewong, Wanchai

2015-03-01

A real-time fluorescence resonance energy transfer polymerase chain reaction (qFRET PCR) coupled with melting curve analysis was developed for detection of Babesia canis vogeli and Hepatozoon canis infections in canine blood samples in a single tube assay. The target of the assay was a region within the 18S ribosomal RNA gene amplified in either species by a single pair of primers. Following amplification from the DNA of infected dog blood, a fluorescence melting curve analysis was done. The 2 species, B. canis vogeli and H. canis, could be detected and differentiated in infected dog blood samples (n = 37) with high sensitivity (100%). The detection limit for B. canis vogeli was 15 copies of a positive control plasmid, and for H. canis, it was 150 copies of a positive control plasmid. The assay could simultaneously distinguish the DNA of both parasites from the DNA of controls. Blood samples from 5 noninfected dogs were negative, indicating high specificity. Several samples can be run at the same time. The assay can reduce misdiagnosis and the time associated with microscopic examination, and is not prone to the carryover contamination associated with the agarose gel electrophoresis step of conventional PCR. In addition, this qFRET PCR method would be useful to accurately determine the range of endemic areas or to discover those areas where the 2 parasites co-circulate. © 2015 The Author(s).

Survival curves study of platelet labelling with 51Cr

International Nuclear Information System (INIS)

Penas, M.E.

1981-01-01

Platelet kinetics and idiopathic thrombocytopenic purpura were researched in the literature. An 'in vitro' platelet labelling with 51 Cr procedure in implementation has been evaluated in human beings. Functions used for fitting considered the cases whether the curve was linear or exponential as well as the presence of hematies. (author)

Predicting long-term graft survival in adult kidney transplant recipients

Directory of Open Access Journals (Sweden)

Brett W Pinsky

2012-01-01

Full Text Available The ability to accurately predict a population′s long-term survival has important implications for quantifying the benefits of transplantation. To identify a model that can accurately predict a kidney transplant population′s long-term graft survival, we retrospectively studied the United Network of Organ Sharing data from 13,111 kidney-only transplants completed in 1988- 1989. Nineteen-year death-censored graft survival (DCGS projections were calculated and com-pared with the population′s actual graft survival. The projection curves were created using a two-part estimation model that (1 fits a Kaplan-Meier survival curve immediately after transplant (Part A and (2 uses truncated observational data to model a survival function for long-term projection (Part B. Projection curves were examined using varying amounts of time to fit both parts of the model. The accuracy of the projection curve was determined by examining whether predicted sur-vival fell within the 95% confidence interval for the 19-year Kaplan-Meier survival, and the sample size needed to detect the difference in projected versus observed survival in a clinical trial. The 19-year DCGS was 40.7% (39.8-41.6%. Excellent predictability (41.3% can be achieved when Part A is fit for three years and Part B is projected using two additional years of data. Using less than five total years of data tended to overestimate the population′s long-term survival, accurate prediction of long-term DCGS is possible, but requires attention to the quantity data used in the projection method.

The microculture-kinetic (MiCK) assay: the role of a drug-induced apoptosis assay in drug development and clinical care.

Science.gov (United States)

Bosserman, Linda; Prendergast, Franklyn; Herbst, Roy; Fleisher, Martin; Salom, Emery; Strickland, Steven; Raptis, Anastasios; Hallquist, Allan; Perree, Mathieu; Rajurkar, Swapnil; Karimi, Misagh; Rogers, Karl; Davidson, Dirk; Willis, Carl; Penalver, Manuel; Homesley, Howard; Burrell, Matthew; Garrett, Audrey; Rutledge, James; Chernick, Michael; Presant, Cary A

2012-08-15

A drug-induced apoptosis assay, termed the microculture-kinetic (MiCK) assay, has been developed. Blinded clinical trials have shown higher response rates and longer survival in groups of patients with acute myelocytic leukemia and epithelial ovarian cancer who have been treated with drugs that show high apoptosis in the MiCK assay. Unblinded clinical trials in multiple tumor types have shown that the assay will be used frequently by clinicians to determine treatment, and when used, results in higher response rates, longer times to relapse, and longer survivals. Model economic analyses suggest possible cost savings in clinical use based on increased generic drug use and single-agent substitution for combination therapies. Two initial studies with drugs in development are promising. The assay may help reduce costs and speed time to drug approval. Correlative studies with molecular biomarkers are planned. This assay may have a role both in personalized clinical therapy and in more efficient drug development. ©2012 AACR.

Burial duration, depth and air pocket explain avalanche survival patterns in Austria and Switzerland.

Science.gov (United States)

Procter, Emily; Strapazzon, Giacomo; Dal Cappello, Tomas; Zweifel, Benjamin; Würtele, Andreas; Renner, Andreas; Falk, Markus; Brugger, Hermann

2016-08-01

To calculate the first Austrian avalanche survival curve and update a Swiss survival curve to explore survival patterns in the Alps. Avalanche accidents occurring between 2005/06 and 2012/13 in Austria and Switzerland were collected. Completely buried victims (i.e. burial of the head and chest) in open terrain with known outcome (survived or not survived) were included in the analysis. Extrication and survival curves were calculated using the Turnbull algorithm, as in previous studies. 633 of the 796 completely buried victims were included (Austria n=333, Switzerland n=300). Overall survival was 56% (Austria 59%; Switzerland 52%; p=0.065). Time to extrication was shorter in Austria for victims buried ≤60min (p15min. The survival curves resembled those previously published and support the idea that underlying survival patterns are reproducible. The results are in accordance with current recommendations for management of avalanche victims and serve as a reminder that expedient companion rescue within a few minutes is critical for survival. An air pocket was shown to be a positive prognostic factor for survival. Copyright © 2016 Elsevier Ireland Ltd. All rights reserved.

Survival of human diploid skin fibroblasts from normal individuals after X-irradiation

International Nuclear Information System (INIS)

Little, J.B.; Nove, J.; Strong, L.C.; Nichols, W.W.

1988-01-01

The cytotoxic effect of X-rays was measured by a colony formation assay in multiple experiments with fibroblast cell strains derived from 24 presumably normal individuals, received as 65 different coded and blinded samples. Each strain was received on two or more occasions at different times and bearing different codes. The means and standard deviations of the survival curve parameters for the 24 strains were: D 0 = 123 +- 23; D 10 = 273 +- 42 cGy. The D 0 ranged from 89 to 175 and the D 10 from 196 to 372 cGy. The degree of interexperimental variation, though generally minimal, differed considerably among cell strains. There was no systematic effect of passage level, cloning efficiency, serum lot, age or sex of the donor on X-ray survival. These results confirm that the intrinsic radiosensitivity varies significantly among skin fibroblasts isolated from clinically normal individuals, apparently owing to as yet unidentified genetic factors. (Author)

On the analysis of clonogenic survival data: Statistical alternatives to the linear-quadratic model

International Nuclear Information System (INIS)

Unkel, Steffen; Belka, Claus; Lauber, Kirsten

2016-01-01

The most frequently used method to quantitatively describe the response to ionizing irradiation in terms of clonogenic survival is the linear-quadratic (LQ) model. In the LQ model, the logarithm of the surviving fraction is regressed linearly on the radiation dose by means of a second-degree polynomial. The ratio of the estimated parameters for the linear and quadratic term, respectively, represents the dose at which both terms have the same weight in the abrogation of clonogenic survival. This ratio is known as the α/β ratio. However, there are plausible scenarios in which the α/β ratio fails to sufficiently reflect differences between dose-response curves, for example when curves with similar α/β ratio but different overall steepness are being compared. In such situations, the interpretation of the LQ model is severely limited. Colony formation assays were performed in order to measure the clonogenic survival of nine human pancreatic cancer cell lines and immortalized human pancreatic ductal epithelial cells upon irradiation at 0-10 Gy. The resulting dataset was subjected to LQ regression and non-linear log-logistic regression. Dimensionality reduction of the data was performed by cluster analysis and principal component analysis. Both the LQ model and the non-linear log-logistic regression model resulted in accurate approximations of the observed dose-response relationships in the dataset of clonogenic survival. However, in contrast to the LQ model the non-linear regression model allowed the discrimination of curves with different overall steepness but similar α/β ratio and revealed an improved goodness-of-fit. Additionally, the estimated parameters in the non-linear model exhibit a more direct interpretation than the α/β ratio. Dimensionality reduction of clonogenic survival data by means of cluster analysis was shown to be a useful tool for classifying radioresistant and sensitive cell lines. More quantitatively, principal component analysis allowed

Irradiations of human melanoma cells by 14 MeV neutrons; survival curves interpretation; physical simulation of neutrons interactions in the cellular medium

International Nuclear Information System (INIS)

Bodez, Veronique

2000-01-01

14 MeV neutrons are used to irradiate human melanoma cells in order to study survival curves at low dose and low dose rate. We have simulated with the MCNP code, transport of neutrons through the experimental setup to evaluate the contamination of the primary beam by gamma and electrons, for the feasibility of our experiments. We have shown a rapid decrease of the survival curve in the first cGy followed by a plateau for doses up to 30 cGy; after we observed an exponential decrease. This results are observed for the first time, for neutrons at low dose rate (5 cGy/h). In parallel with this experimental point, we have developed a simulation code which permitted the study of neutrons interactions with the cellular medium for individual cells defined as in our experimental conditions. We show that most of the energy is deposited by protons from neutron interactions with external medium, and by heavy ions for interactions into the cell. On the other hand the code gives a good order of magnitude of the dose rate, compared to the experimental values given by silicon diodes. The first results show that we can, using a theory based on induced repair of cells, give an interpretation of the observed experimental plateau. We can give an estimation of the radial distribution of dose for the tracks of charged ions, we show the possibility of calculate interaction cross sections with cellular organelles. Such a work gives interesting perspectives for the future in radiobiology, radiotherapy or radioprotection. (author) [fr

A mathematical model resolving normal human blood lymphocyte population X-ray survival curves into six components: radiosensitivity, death rate and size of two responding sub-populations

International Nuclear Information System (INIS)

Thomson, A.E.R.; Vaughan-Smith, S.; Peel, W.E.

1982-01-01

The analysis was based on observations of survival decrease as a function of dose (range 0-5 Gy (= 500 rad)) and time after irradiation in vitro. Since lymphocyte survival is also sensitive to culture conditions the effects of radiation were examined daily up to 3 days only, while survival of control cells remained ca. 90 per cent. The time-dependent changes were resolved as the death rates (first-order governed) of lethally-hit cells (apparent survivors), so rendering these distinguishable from the morphologically identical, true (ultimate) survivors. For 12 blood donors the estimated dose permitting 37 per cent ultimate survival (D 37 value) averaged 0.72 +- 0.18 (SD) Gy for the more radiosensitive lymphocyte fraction and 2.50 +- 0.67 Gy for the less radiosensitive, each fraction proving homogeneously radiosensitive and the latter identifying substantially in kind with T-type (E-rosetting lymphocytes). The half-life of lethally-hit members of either fraction varied widely among the donors (ranges, 25-104 hours and 11-40 hours, respectively). Survival curves reconstructed by summating the numerical estimates of the six parameters according to the theoretical model closely matched those observed experimentally (ranged in multiple correlation coefficient, 0.9709-0.9994) for all donors). This signified the absence of any additional, totally radioresistant cell fraction. (author)

Applied survival analysis using R

CERN Document Server

Moore, Dirk F

2016-01-01

Applied Survival Analysis Using R covers the main principles of survival analysis, gives examples of how it is applied, and teaches how to put those principles to use to analyze data using R as a vehicle. Survival data, where the primary outcome is time to a specific event, arise in many areas of biomedical research, including clinical trials, epidemiological studies, and studies of animals. Many survival methods are extensions of techniques used in linear regression and categorical data, while other aspects of this field are unique to survival data. This text employs numerous actual examples to illustrate survival curve estimation, comparison of survivals of different groups, proper accounting for censoring and truncation, model variable selection, and residual analysis. Because explaining survival analysis requires more advanced mathematics than many other statistical topics, this book is organized with basic concepts and most frequently used procedures covered in earlier chapters, with more advanced topics...

Additive effects of 5-Aza-2'-deoxycytidine and irradiation on clonogenic survival of human medulloblastoma cell lines

Energy Technology Data Exchange (ETDEWEB)

Patties, Ina; Jahns, Jutta; Kortmann, Rolf-Dieter; Glasow, Annegret [Dept. of Radiotherapy and Radiooncology, Universitaetsklinikum Leipzig AoeR (Germany); Hildebrandt, Guido [Dept. of Radiotherapy and Radiooncology, Universitaetsklinikum Leipzig AoeR (Germany); Dept. of Radiotherapy, Univ. of Rostock (Germany)

2009-05-15

Background and purpose: in recent years, epigenetic modulators were introduced into tumor therapy. Here, the authors investigated the antitumor effect of 5-aza-2'-deoxycytidine-(5-aza-dC-)induced demethylation combined with irradiation on human medulloblastoma (MB) cells, which form the most common malignant brain tumor in children. Material and methods: three MB cell lines were treated with 5-aza-dC in a low-dose (0.1 {mu}M, 6 days) or high-dose (3/5 {mu}M, 3 days) setting and irradiated with 2, 4, 6, or 8 Gy single dose on an X-ray unit. Methylation status and mRNA expression of three candidate genes were analyzed by methylation-specific PCR (polymerase chain reaction) and quantitative real-time RT-PCR. Cell survival and mortality were determined by trypan blue exclusion test. Proliferation was analyzed by BrdU incorporation assay, and long-term cell survival was assessed by clonogenic assay. Results: 5-aza-dC treatment resulted in partial promoter demethylation and increased expression of hypermethylated candidate genes. A significant decrease of vital cell count, proliferation inhibition and increase of mortality was observed in 5-aza-dC-treated as well as in irradiated MB cells, whereby combination of both treatments led to additive effects. Although high-dose 5-aza-dC treatment was more effective in terms of demethylation, clonogenic assay revealed no differences between high- and low-dose settings indicating no relevance of 5-aza-dC-induced demethylation for decreased cell survival. MB cells pretreated with 5-aza-dC showed significantly lower plating efficiencies than untreated cells at all irradiation doses investigated. Analysis of surviving curves in irradiated MB cells, however, revealed no significant differences of {alpha}-, {beta}-values and 2-Gy surviving fraction with or without 5-aza-dC treatment. Conclusion: 5-aza-dC did not enhance radiation sensitivity of MB cells but significantly reduced the clonogenicity versus irradiation alone, which

Using commercial simulators for determining flash distillation curves for petroleum fractions

OpenAIRE

Eleonora Erdmann; Demetrio Humana; Samuel Franco Domínguez; Lorgio Mercado Fuentes

2010-01-01

This work describes a new method for estimating the equilibrium flash vaporisation (EFV) distillation curve for petro-leum fractions by using commercial simulators. A commercial simulator was used for implementing a stationary mo-del for flash distillation; this model was adjusted by using a distillation curve obtained from standard laboratory ana-lytical assays. Such curve can be one of many types (eg ASTM D86, D1160 or D2887) and involves an experimental procedure simpler than that required...

Botulinum Neurotoxins: Qualitative and Quantitative Analysis Using the Mouse Phrenic Nerve Hemidiaphragm Assay (MPN

Directory of Open Access Journals (Sweden)

Hans Bigalke

2015-11-01

Full Text Available The historical method for the detection of botulinum neurotoxin (BoNT is represented by the mouse bioassay (MBA measuring the animal survival rate. Since the endpoint of the MBA is the death of the mice due to paralysis of the respiratory muscle, an ex vivo animal replacement method, called mouse phrenic nerve (MPN assay, employs the isolated N. phrenicus-hemidiaphragm tissue. Here, BoNT causes a dose-dependent characteristic decrease of the contraction amplitude of the indirectly stimulated muscle. Within the EQuATox BoNT proficiency 13 test samples were analysed using the MPN assay by serial dilution to a bath concentration resulting in a paralysis time within the range of calibration curves generated with BoNT/A, B and E standards, respectively. For serotype identification the diluted samples were pre-incubated with polyclonal anti-BoNT/A, B or E antitoxin or a combination of each. All 13 samples were qualitatively correctly identified thereby delivering superior results compared to single in vitro methods like LFA, ELISA and LC-MS/MS. Having characterized the BoNT serotype, the final bath concentrations were calculated using the calibration curves and then multiplied by the respective dilution factor to obtain the sample concentration. Depending on the source of the BoNT standards used, the quantitation of ten BoNT/A containing samples delivered a mean z-score of 7 and of three BoNT/B or BoNT/E containing samples z-scores <2, respectively.

Multi-binding site model-based curve-fitting program for the computation of RIA data

International Nuclear Information System (INIS)

Malan, P.G.; Ekins, R.P.; Cox, M.G.; Long, E.M.R.

1977-01-01

In this paper, a comparison will be made of model-based and empirical curve-fitting procedures. The implementation of a multiple binding-site curve-fitting model which will successfully fit a wide range of assay data, and which can be run on a mini-computer is described. The latter sophisticated model also provides estimates of binding site concentrations and the values of the respective equilibrium constants present: the latter have been used for refining assay conditions using computer optimisation techniques. (orig./AJ) [de

Radioligand assays - methods and applications. IV. Uniform regression of hyperbolic and linear radioimmunoassay calibration curves

Energy Technology Data Exchange (ETDEWEB)

Keilacker, H; Becker, G; Ziegler, M; Gottschling, H D [Zentralinstitut fuer Diabetes, Karlsburg (German Democratic Republic)

1980-10-01

In order to handle all types of radioimmunoassay (RIA) calibration curves obtained in the authors' laboratory in the same way, they tried to find a non-linear expression for their regression which allows calibration curves with different degrees of curvature to be fitted. Considering the two boundary cases of the incubation protocol they derived a hyperbolic inverse regression function: x = a/sub 1/y + a/sub 0/ + asub(-1)y/sup -1/, where x is the total concentration of antigen, asub(i) are constants, and y is the specifically bound radioactivity. An RIA evaluation procedure based on this function is described providing a fitted inverse RIA calibration curve and some statistical quality parameters. The latter are of an order which is normal for RIA systems. There is an excellent agreement between fitted and experimentally obtained calibration curves having a different degree of curvature.

Equivalent intraperitoneal doses of ibuprofen supplemented in drinking water or in diet: a behavioral and biochemical assay using antinociceptive and thromboxane inhibitory dose–response curves in mice

Directory of Open Access Journals (Sweden)

Raghda A.M. Salama

2016-07-01

Full Text Available Background. Ibuprofen is used chronically in different animal models of inflammation by administration in drinking water or in diet due to its short half-life. Though this practice has been used for years, ibuprofen doses were never assayed against parenteral dose–response curves. This study aims at identifying the equivalent intraperitoneal (i.p. doses of ibuprofen, when it is administered in drinking water or in diet. Methods. Bioassays were performed using formalin test and incisional pain model for antinociceptive efficacy and serum TXB2 for eicosanoid inhibitory activity. The dose–response curve of i.p. administered ibuprofen was constructed for each test using 50, 75, 100 and 200 mg/kg body weight (b.w.. The dose–response curves were constructed of phase 2a of the formalin test (the most sensitive phase to COX inhibitory agents, the area under the ‘change in mechanical threshold’-time curve in the incisional pain model and serum TXB2 levels. The assayed ibuprofen concentrations administered in drinking water were 0.2, 0.35, 0.6 mg/ml and those administered in diet were 82, 263, 375 mg/kg diet. Results. The 3 concentrations applied in drinking water lay between 73.6 and 85.5 mg/kg b.w., i.p., in case of the formalin test; between 58.9 and 77.8 mg/kg b.w., i.p., in case of the incisional pain model; and between 71.8 and 125.8 mg/kg b.w., i.p., in case of serum TXB2 levels. The 3 concentrations administered in diet lay between 67.6 and 83.8 mg/kg b.w., i.p., in case of the formalin test; between 52.7 and 68.6 mg/kg b.w., i.p., in case of the incisional pain model; and between 63.6 and 92.5 mg/kg b.w., i.p., in case of serum TXB2 levels. Discussion. The increment in pharmacological effects of different doses of continuously administered ibuprofen in drinking water or diet do not parallel those of i.p. administered ibuprofen. It is therefore difficult to assume the equivalent parenteral daily doses based on mathematical calculations.

Survival curves of irradiated glutathione-deficient human fibroblasts: indication of a reduced enhancement of radiosensitivity by oxygen and misonidazole

International Nuclear Information System (INIS)

Midander, J.; Deschavanne, P.J.; Malaise, E.P.; Revesz, L.

1982-01-01

Fibroblasts derived from a patient with 5-oxoprolinuria are genetically deficient in glutathione synthetase. This deficiency causes a dramatic decrease in intracellular glutathione (GSH) level. The radiosensitivity of GSH deficient cells (GSH) was studied in vitro using colony forming ability as an endpoint. Cells with normal GSH level, obtained from the healthy brother of the patient, were used as controls. When irradiated in 95% air-5% CO 2 , GSH - cells are slightly but significantly more radiosensitive than GSH + controls (dose modifying factor (DMF) of 1.2). When irradiated in argon, the survival curve of GSH - cells indicates an oxygen enhancement ratio (OER) of 1.5 when compared to the curve obtained in oxic conditions. The OER of control cells in the same conditions is 2.9. In comparison to results obtained in air, 100% oxygen moderately increases the radiosensitivity of GSH + cells (DMF 1,23), while it has a very low effect on GSH - cells (DMF 1.06). These results suggest that intracellular GSH plays an essential protective role in hypoxia, its effect is reduced in air and practically disappears in 100% oxygen. When cells are incubated with 8 mM misonidazole 2 hours before irradiation, the drug has a much greater sensitizing effect on GSH + cells (DMF 2.33) than on GSH - cells (DMF 1.55). The results demonstrate that intracellular GSH level plays a major role in the response of hypoxic cells, irradiated either alone or in the presence of misonidazole

Direct assay for urine cortisol with cortisol kit TFB

Energy Technology Data Exchange (ETDEWEB)

Manaka, Yukiko; Watanabe, Michiko; Hosoya, Takaaki [Yamagata Univ. (Japan). Hospital

2002-05-01

We examined Cortisol Kit TFB for direct assay of urine cortisol. And the multiplication by dilution factor of urine cortisol values in this kit was examined. The coefficient of correlation of cortisol levels (46 urine samples) between Cortisol Kit TFB and Chemilumi ACS-Cortisol II, which is another kit for direct assay of urine cortisol, was r=0.858, y=1.86x+38.2 (p<0.001). There were differences between the both cortisol levels of each urine sample in spite of the good coefficient of correlation. The urine cortisol values obtained from the standard curve in addition of 50 {mu}l of zero standard were 50-80% of the values obtained from the standard curve in the package insert. These results suggest that the specificity of the antibodies of both direct assay kits for urine cortisol may be different each other, and the multiplication by 1.09, the dilution factor due to the addition of zero standard to only urine sample, is unnecessary although it is indispensable for urine samples to add zero standard. Cortisol Kit TFB was very convenient for its easy assay procedure and short incubation. (author)

Direct assay for urine cortisol with cortisol kit TFB

International Nuclear Information System (INIS)

Manaka, Yukiko; Watanabe, Michiko; Hosoya, Takaaki

2002-01-01

We examined Cortisol Kit TFB for direct assay of urine cortisol. And the multiplication by dilution factor of urine cortisol values in this kit was examined. The coefficient of correlation of cortisol levels (46 urine samples) between Cortisol Kit TFB and Chemilumi ACS-Cortisol II, which is another kit for direct assay of urine cortisol, was r=0.858, y=1.86x+38.2 (p<0.001). There were differences between the both cortisol levels of each urine sample in spite of the good coefficient of correlation. The urine cortisol values obtained from the standard curve in addition of 50 μl of zero standard were 50-80% of the values obtained from the standard curve in the package insert. These results suggest that the specificity of the antibodies of both direct assay kits for urine cortisol may be different each other, and the multiplication by 1.09, the dilution factor due to the addition of zero standard to only urine sample, is unnecessary although it is indispensable for urine samples to add zero standard. Cortisol Kit TFB was very convenient for its easy assay procedure and short incubation. (author)

Influence of preirradiational and postirradiational heating of lyophilized Micrococcus radioproteolyticus cells on their survival

Energy Technology Data Exchange (ETDEWEB)

Ryznar, L; Drasil, V [Ceskoslovenska Akademie Ved, Brno. Biofysikalni Ustav

1981-12-10

The survival curve of Micrococcus radioproteolyticus following gamma irradiation of lyophilized cells is characterized by a broad shoulder reaching as far as the dose range 10 - 20 kGy (1 - 2 Mrad). The course of the curve indicates that under these conditions most of the changes induced by irradiation have the character of sublethal damage, which the cell can repair. The course of the survival curve does not change if the lyophilized cells are heated prior to irradiation for 2 h at 60 /sup 0/C. Certain changes do occur if the preirradiational temperature is 80 /sup 0/C. If the cells are exposed to increased temperature after irradiation even a temperature of 60 /sup 0/C brings about a marked decrease in survival. A temperature of 80 /sup 0/C after irradiation leads to extensive changes in the shape of survival curves, which are characterized by a narrowing or even disappearing of the shoulders. It can be concluded from the results obtained that an increased temperature modifies the capability of irradiated lyophilized cells to repair radiation damage.

Influence of preirradiational and postirradiational heating of lyophilized Micrococcus radioproteolyticus cells on their survival

International Nuclear Information System (INIS)

Ryznar, L.; Drasil, V.

1981-01-01

The survival curve of Micrococcus radioproteolyticus following gamma irradiation of lyophilized cells is characterized by a broad shoulder reaching as far as the dose range 10 - 20 kGy (1 - 2 Mrad). The course of the curve indicates that under these conditions most of the changes induced by irradiation have the character of sublethal damage, which the cell can repair. The course of the survival curve does not change if the lyophilized cells are heated prior to irradiation for 2 h at 60 0 C. Certain changes do occur if the preirradiational temperature is 80 0 C. If the cells are exposed to increased temperature after irradiation even a temperature of 60 0 C brings about a marked decrease in survival. A temperature of 80 0 C after irradiation leads to extensive changes in the shape of survival curves, which are characterized by a narrowing or even disappearing of the shoulders. It can be concluded from the results obtained that an increased temperature modifies the capability of irradiated lyophilized cells to repair radiation damage. (author)

Ensemble of cell survival experiments after ion irradiation for validation of RBE models

Energy Technology Data Exchange (ETDEWEB)

Friedrich, Thomas; Scholz, Uwe; Scholz, Michael [GSI Helmholtzzentrum fuer Schwerionenforschung, Darmstadt (Germany); Durante, Marco [GSI Helmholtzzentrum fuer Schwerionenforschung, Darmstadt (Germany); Institut fuer Festkoerperphysik, TU Darmstadt, Darmstadt (Germany)

2012-07-01

There is persistent interest in understanding the systematics of the relative biological effectiveness (RBE). Models such as the Local Effect Model (LEM) or the Microdosimetric Kinetic Model have the goal to predict the RBE. For the validation of these models a collection of many in-vitro cell survival experiments is most appropriate. The set-up of an ensemble of in-vitro cell survival data comprising about 850 survival experiments after both ion and photon irradiation is reported. The survival curves have been taken out from publications. The experiments encompass survival curves obtained in different labs, using different ion species from protons to uranium, varying irradiation modalities (shaped or monoenergetic beam), various energies and linear energy transfers, and a whole variety of cell types (human or rodent; normal, mutagenic or tumor; radioresistant or -sensitive). Each cell survival curve has been parameterized by the linear-quadratic model. The photon parameters have been added to the data base to allow to calculate the experimental RBE to any survival level. We report on experimental trends found within the data ensemble. The data will serve as a testing ground for RBE models such as the LEM. Finally, a roadmap for further validation and first model results using the data base in combination with the LEM are presented.

P-gp Expression and Rh 123 Efflux Assay Have no Impact on Survival in Egyptian Pediatric Acute Lymphoblastic Leukemia Patients

International Nuclear Information System (INIS)

Kamel, A.M.; El-Sharkawy, N.; Yassin, D.; Shaaban, Kh.; Hussein, H.; Sidhom, I; Abo El-Naga, S.; Ameen, M.; El-Hattab, O.; Aly El-Din, N.H.

2005-01-01

. In ANLL P-gp expression was encountered in 47.6% of cases, while positive Rh 123 efflux assay was encountered in 75% of cases. No correlation as encountered between neither expression nor Rh 123 efflux assay and neither age, Hb, TLC, CD34 expression nor FAB subtypes. Neither P-gp expression nor Rh 123 efflux assay has any impact on survival in pediatric ALL. Rh 123 ratio of 1.25 is predictive of CR in TALL

Intracellular contacts - effect of survival curve of mammal cells on the Dq value

International Nuclear Information System (INIS)

Durand, R.E.; Sutherland, R.M.

1980-01-01

Survival increase is observed in cells of the Chinese hamster of the V79-171 line which grow in the composition of multicell spheroids as compared with the survival after irradiation in a single state. The ratio of the Dsub(q) cell value in the composition of spheroids to Dsub(q) of separately growing cells increases as the mitotic cycle proceeds from the minimum value of 1.3 for cells in the Gi phase to the maximum value of 2.2 for cells in a late S-phase. The increase of survival during growth in the composition of spheroids is not characteristic for all cell types. Only a part of cultured MNNG-mutants of cells of the V79-171 Chinese hamster reveal radiomodifying effect of cell contact acting [ru

Evaluation of the Comet Assay for Assessing the Dose-Response Relationship of DNA Damage Induced by Ionizing Radiation

Science.gov (United States)

Wang, Yan; Xu, Chang; Du, Li Qing; Cao, Jia; Liu, Jian Xiang; Su, Xu; Zhao, Hui; Fan, Fei-Yue; Wang, Bing; Katsube, Takanori; Fan, Sai Jun; Liu, Qiang

2013-01-01

Dose- and time-response curves were combined to assess the potential of the comet assay in radiation biodosimetry. The neutral comet assay was used to detect DNA double-strand breaks in lymphocytes caused by γ-ray irradiation. A clear dose-response relationship with DNA double-strand breaks using the comet assay was found at different times after irradiation (p < 0.001). A time-response relationship was also found within 72 h after irradiation (p < 0.001). The curves for DNA double-strand breaks and DNA repair in vitro of human lymphocytes presented a nice model, and a smooth, three-dimensional plane model was obtained when the two curves were combined. PMID:24240807

Evaluation of the Comet Assay for Assessing the Dose-Response Relationship of DNA Damage Induced by Ionizing Radiation

Directory of Open Access Journals (Sweden)

Qiang Liu

2013-11-01

Full Text Available Dose- and time-response curves were combined to assess the potential of the comet assay in radiation biodosimetry. The neutral comet assay was used to detect DNA double-strand breaks in lymphocytes caused by γ-ray irradiation. A clear dose-response relationship with DNA double-strand breaks using the comet assay was found at different times after irradiation (p < 0.001. A time-response relationship was also found within 72 h after irradiation (p < 0.001. The curves for DNA double-strand breaks and DNA repair in vitro of human lymphocytes presented a nice model, and a smooth, three-dimensional plane model was obtained when the two curves were combined.

New graphic AUC-based method to estimate overall survival benefit: pomalidomide reanalysis.

Science.gov (United States)

Fenix-Caballero, S; Diaz-Navarro, J; Prieto-Callejero, B; Rios-Sanchez, E; Alegre-del Rey, E J; Borrero-Rubio, J M

2016-02-01

Difference in median survival is an erratic measure and sometimes does not provide a good assessment of survival benefit. The aim of this study was to reanalyse the overall survival benefit of pomalidomide from pivotal clinical trial using a new area under curve (AUC)-based method. In the pivotal trial, pomalidomide plus low-dose dexamethasone showed a significant survival benefit over high-dose dexamethasone, with a difference between medians of 4.6 months. The new AUC method applied to the survival curves, obtained an overall survival benefit of 2.6 months for the pomalidomide treatment. This average difference in OS was calculated for the 61.5% of patients for whom the time to event is reliable enough. This 2-month differential would have major clinical and pharmacoeconomic implications, on both cost-effectiveness studies and on the willingness of the healthcare systems to pay for this treatment. © 2015 John Wiley & Sons Ltd.

Survival and mortality among users and non-users of hydroxyurea with sickle cell disease.

Science.gov (United States)

de Araujo, Olinda Maria Rodrigues; Ivo, Maria Lúcia; Ferreira Júnior, Marcos Antonio; Pontes, Elenir Rose Jardim Cury; Bispo, Ieda Maria Gonçalves Pacce; de Oliveira, Eveny Cristine Luna

2015-01-01

to estimate survival, mortality and cause of death among users or not of hydroxyurea with sickle cell disease. cohort study with retrospective data collection, from 1980 to 2010 of patients receiving inpatient treatment in two Brazilian public hospitals. The survival probability was determined using the Kaplan-Meier estimator, survival calculations (SPSS version 10.0), comparison between survival curves, using the log rank method. The level of significance was p=0.05. of 63 patients, 87% had sickle cell anemia, with 39 using hydroxyurea, with a mean time of use of the drug of 20.0±10.0 years and a mean dose of 17.37±5.4 to 20.94±7.2 mg/kg/day, raising the fetal hemoglobin. In the comparison between those using hydroxyurea and those not, the survival curve was greater among the users (p=0.014). A total of 10 deaths occurred, with a mean age of 28.1 years old, and with Acute Respiratory Failure as the main cause. the survival curve is greater among the users of hydroxyurea. The results indicate the importance of the nurse incorporating therapeutic advances of hydroxyurea in her care actions.

Development of in vitro assay method with radioisotope

International Nuclear Information System (INIS)

Choi, Chang Woon; Lim, S. M.; An, S. H.; Woo, K. S.; Chung, W. S.; Lim, S. J.; Hong, S. W.; Oh, O. D.

1999-04-01

Radioimmunoassay (RIA) and related competitive protein-binding methods began a little over 20 years ago as a cumbersome research methodology in a few specialized laboratories. Endocrinology has been greatly enriched by the new knowledge that has come as a direct result of RIA methods. Establishment of the taxol RIA system will be expected to develop RIA for drug monitoring. Scintillation proximity assay was useful since any separation step is not required, it has the advantage of dealing with multiple samples. The increased sensitivity of the new assay in determining HCV RT([ 125 I]dUTP) suggests that it would be worth investigating whether the system can be applied to analysis. [ 125 I] lodotyramine with 98.5% radiochemical purity. Optimal background counts was certificated using varied radioactivity of radionuclides. Appropriate standard curve was obtained from SPA method successively, and the concentration of hCG from unknown serum was determined by standard curve. The result concentration of hCG from unknown serum was determined by synthesized successively and purified by HPLC system. Hybridoma reducing monoclonal anti thyroglobulin antibodies titer is measured by ELISA. These studies play an important role in development of in vitro assay with radionuclides

Development of in vitro assay method with radioisotope

Energy Technology Data Exchange (ETDEWEB)

Choi, Chang Woon; Lim, S. M.; An, S. H.; Woo, K. S.; Chung, W. S.; Lim, S. J.; Hong, S. W. [Korea Atomic Energy Research Institute. Korea Cancer Center Hospital, Seoul (Korea, Republic of); Oh, O. D. [Yonsei University, Seoul (Korea, Republic of)

1999-04-01

Radioimmunoassay (RIA) and related competitive protein-binding methods began a little over 20 years ago as a cumbersome research methodology in a few specialized laboratories. Endocrinology has been greatly enriched by the new knowledge that has come as a direct result of RIA methods. Establishment of the taxol RIA system will be expected to develop RIA for drug monitoring. Scintillation proximity assay was useful since any separation step is not required, it has the advantage of dealing with multiple samples. The increased sensitivity of the new assay in determining HCV RT([{sup 125}I]dUTP) suggests that it would be worth investigating whether the system can be applied to analysis. [{sup 125}I] lodotyramine with 98.5% radiochemical purity. Optimal background counts was certificated using varied radioactivity of radionuclides. Appropriate standard curve was obtained from SPA method successively, and the concentration of hCG from unknown serum was determined by standard curve. The result concentration of hCG from unknown serum was determined by synthesized successively and purified by HPLC system. Hybridoma reducing monoclonal anti thyroglobulin antibodies titer is measured by ELISA. These studies play an important role in development of in vitro assay with radionuclides.

Enzyme-immuno assay for total estrogens and human placental lactogen. Comparison with radio-immuno-assay in normal pregnancy-monitoring

International Nuclear Information System (INIS)

Raichvarg, D.; Tallet, F.; Lajeunie, E.; Bonnaire, Y.; Danglas, P.

1980-01-01

The concentrations of estrogens (E) and human placental lactogen (HLP) are estimated in sera by radio immuno-assay (RIA) and enzyme-immuno-assay (EIA). Statistical data indicate mean intra-assay variation coefficients of 7% and 12% for E and HLP tests, respectively. The correlation coefficient (RIA/EIA) are found higher than 0,9% for both hormonal assays. The dilution curves obtained by RIA and EIA are similar. However, Student'test gives a significant difference for E determination. In fact, total E and E 3 only are measured by EIA and RIA, respectively. In most cases biological interferences are negligible except for HLP in presence of higher protein or haemoglobin levels. RIA and EIA are performed to study serum HLP and E levels throughout normal pregnancies. Results allow to use EIA for HLP and E evaluations in pregnancy-monitoring [fr

Survival of Patients With Cervical Cancer in Rural India

OpenAIRE

Vinoda Thulaseedharan, Jissa; Malila, Nea; Swaminathan, Rajaraman; Esmy Pulikottil, Okuru; Hakama, Matti; Muwonge, Richard; Sankaranarayanan, Rengaswamy

2015-01-01

Background: Patients’ survival after diagnosis of cervical cancer is indirectly influenced by socio-economic factors. We evaluated this survival and its socio-economic determinants in a rural population in south India. Methods: We assessed 165 women diagnosed with cervical cancer from the routine care control arm of a randomized screening trial conducted in rural south India. Kaplan-Meier curves were plotted to illustrate the observed survival of cancer patients. The effect of socio-econom...

Using Survival Analysis to Evaluate Medical Equipment Battery Life.

Science.gov (United States)

Kuhajda, David

2016-01-01

As hospital medical device managers obtain more data, opportunities exist for using the data to improve medical device management, enhance patient safety, and evaluate costs of decisions. As a demonstration of the ability to use data analytics, this article applies survival analysis statistical techniques to assist in making decisions on medical equipment maintenance. The analysis was performed on a large amount of data related to failures of an infusion pump manufacturer's lithium battery and two aftermarket replacement lithium batteries from one hospital facility. The survival analysis resulted in statistical evidence showing that one of the third-party batteries had a lower survival curve than the infusion pump manufacturer's battery. This lower survival curve translates to a shorter expected life before replacement is needed. The data suggested that to limit unexpected failures, replacing batteries at a two-year interval, rather than the current industry recommendation of three years, may be warranted. For less than $5,400 in additional annual cost, the risk of unexpected battery failures can be reduced from an estimated 28% to an estimated 7%.

The statistical treatment of cell survival data

International Nuclear Information System (INIS)

Boag, J.W.

1975-01-01

The paper considers the sources of experimental error in cell survival experiments and discusses in simple terms how these combine to influence the accuracy of single points and the parameters of complete survival curves. Cell sampling and medium-dilution errors are discussed at length and one way of minimizing the former is examined. The Monte-Carlo method of estimating the distribution of derived parameters in small samples is recommended and illustrated. (author)

Radioimmunoassays and 2-site immunoradiometric "sandwich" assays: basic principles.

Science.gov (United States)

Rodbard, D

1988-10-01

The "sandwich" or noncompetitive reagent-excess, 2-site immunoradiometric assay (2-site IRMA), ELISA, USERIA, and related techniques, have several advantages compared with the traditional or competitive radioimmunoassays. IRMAs can provide improved sensitivity and specificity. However, IRMAs present some practical problems with nonspecific binding, increased consumption of antibody, biphasic dose response curve, (high dose hook effect), and may require special techniques for dose response curve analysis. We anticipate considerable growth in the popularity and importance of 2-site IRMA.

Radioimmunoassays and 2-site immunoradiometric 'sandwich' assays: basic principles

Energy Technology Data Exchange (ETDEWEB)

Rodbard, D

1988-10-01

The 'sandwich' or noncompetitive reagent-excess, 2-site immunoradiometric assay (2-site IRMA), ELISA, USERIA, and related techniques, have several advantages compared with the traditional or competitive radioimmunoassays. IRMAs can provide improved sensitivity and specificity. However, IRMAs present some practical problems with nonspecific binding, increased consumption of antibody, biphasic dose response curve, (high dose hook effect), and may require special techniques for dose response curve analysis. We anticipate considerable growth in the popularity and importance of 2-site IRMA.

Investigating a multigene prognostic assay based on significant pathways for Luminal A breast cancer through gene expression profile analysis.

Science.gov (United States)

Gao, Haiyan; Yang, Mei; Zhang, Xiaolan

2018-04-01

The present study aimed to investigate potential recurrence-risk biomarkers based on significant pathways for Luminal A breast cancer through gene expression profile analysis. Initially, the gene expression profiles of Luminal A breast cancer patients were downloaded from The Cancer Genome Atlas database. The differentially expressed genes (DEGs) were identified using a Limma package and the hierarchical clustering analysis was conducted for the DEGs. In addition, the functional pathways were screened using Kyoto Encyclopedia of Genes and Genomes pathway enrichment analyses and rank ratio calculation. The multigene prognostic assay was exploited based on the statistically significant pathways and its prognostic function was tested using train set and verified using the gene expression data and survival data of Luminal A breast cancer patients downloaded from the Gene Expression Omnibus. A total of 300 DEGs were identified between good and poor outcome groups, including 176 upregulated genes and 124 downregulated genes. The DEGs may be used to effectively distinguish Luminal A samples with different prognoses verified by hierarchical clustering analysis. There were 9 pathways screened as significant pathways and a total of 18 DEGs involved in these 9 pathways were identified as prognostic biomarkers. According to the survival analysis and receiver operating characteristic curve, the obtained 18-gene prognostic assay exhibited good prognostic function with high sensitivity and specificity to both the train and test samples. In conclusion the 18-gene prognostic assay including the key genes, transcription factor 7-like 2, anterior parietal cortex and lymphocyte enhancer factor-1 may provide a new method for predicting outcomes and may be conducive to the promotion of precision medicine for Luminal A breast cancer.

An Engineered Survival-Selection Assay for Extracellular Protein Expression Uncovers Hypersecretory Phenotypes in Escherichia coli.

Science.gov (United States)

Natarajan, Aravind; Haitjema, Charles H; Lee, Robert; Boock, Jason T; DeLisa, Matthew P

2017-05-19

The extracellular expression of recombinant proteins using laboratory strains of Escherichia coli is now routinely achieved using naturally secreted substrates, such as YebF or the osmotically inducible protein Y (OsmY), as carrier molecules. However, secretion efficiency through these pathways needs to be improved for most synthetic biology and metabolic engineering applications. To address this challenge, we developed a generalizable survival-based selection strategy that effectively couples extracellular protein secretion to antibiotic resistance and enables facile isolation of rare mutants from very large populations (i.e., 10 10-12 clones) based simply on cell growth. Using this strategy in the context of the YebF pathway, a comprehensive library of E. coli single-gene knockout mutants was screened and several gain-of-function mutations were isolated that increased the efficiency of extracellular expression without compromising the integrity of the outer membrane. We anticipate that this user-friendly strategy could be leveraged to better understand the YebF pathway and other secretory mechanisms-enabling the exploration of protein secretion in pathogenesis as well as the creation of designer E. coli strains with greatly expanded secretomes-all without the need for expensive exogenous reagents, assay instruments, or robotic automation.

A CpG-methylation-based assay to predict survival in clear cell renal cell carcinoma

Science.gov (United States)

Wei, Jin-Huan; Haddad, Ahmed; Wu, Kai-Jie; Zhao, Hong-Wei; Kapur, Payal; Zhang, Zhi-Ling; Zhao, Liang-Yun; Chen, Zhen-Hua; Zhou, Yun-Yun; Zhou, Jian-Cheng; Wang, Bin; Yu, Yan-Hong; Cai, Mu-Yan; Xie, Dan; Liao, Bing; Li, Cai-Xia; Li, Pei-Xing; Wang, Zong-Ren; Zhou, Fang-Jian; Shi, Lei; Liu, Qing-Zuo; Gao, Zhen-Li; He, Da-Lin; Chen, Wei; Hsieh, Jer-Tsong; Li, Quan-Zhen; Margulis, Vitaly; Luo, Jun-Hang

2015-01-01

Clear cell renal cell carcinomas (ccRCCs) display divergent clinical behaviours. Molecular markers might improve risk stratification of ccRCC. Here we use, based on genome-wide CpG methylation profiling, a LASSO model to develop a five-CpG-based assay for ccRCC prognosis that can be used with formalin-fixed paraffin-embedded specimens. The five-CpG-based classifier was validated in three independent sets from China, United States and the Cancer Genome Atlas data set. The classifier predicts the overall survival of ccRCC patients (hazard ratio=2.96−4.82; P=3.9 × 10−6−2.2 × 10−9), independent of standard clinical prognostic factors. The five-CpG-based classifier successfully categorizes patients into high-risk and low-risk groups, with significant differences of clinical outcome in respective clinical stages and individual ‘stage, size, grade and necrosis' scores. Moreover, methylation at the five CpGs correlates with expression of five genes: PITX1, FOXE3, TWF2, EHBP1L1 and RIN1. Our five-CpG-based classifier is a practical and reliable prognostic tool for ccRCC that can add prognostic value to the staging system. PMID:26515236

Comet assay on mice testicular cells

Directory of Open Access Journals (Sweden)

Anoop Kumar Sharma

2015-05-01

Full Text Available Heritable mutations may result in a variety of adverse outcomes including genetic disease in the offspring. In recent years the focus on germ cell mutagenicity has increased and the “Globally Harmonized System of Classification and Labelling of Chemicals (GHS” has published classification criteria for germ cell mutagens (Speit et al., 2009. The in vivo Comet assay is considered a useful tool for investigating germ cell genotoxicity. In the present study DNA strand breaks in testicular cells of mice were investigated. Different classes of chemicals were tested in order to evaluate the sensitivity of the comet assay in testicular cells. The chemicals included environmentally relevant substances such as Bisphenol A, PFOS and Tetrabrombisphenol A. Statistical power calculations will be presented to aid in the design of future Comet assay studies on testicular cells. Power curves were provided with different fold changes in % tail DNA, different number of cells scored and different number of gels (Hansen et al., 2014. An example is shown in Figure 1. A high throughput version of the Comet assay was used. Samples were scored with a fully automatic comet assay scoring system that provided faster scoring of randomly selected cells.

Discrepancies between measured changes of radiobiological hypoxic fraction and oxygen tension monitoring using two assay systems

International Nuclear Information System (INIS)

Sasai, K.; Brown, J.M.

1994-01-01

This study was conducted to assess the ability of computerized pO 2 histography to measure changes in tumor oxygenation produced by low oxygen breathing. Female syngeneic C3H/Km mice bearing SCC VII/St carcinomas were used in these experiments. Changes in tumor oxygenation produced by the mice breathing 10% oxygen were assessed with computerized pO2 histography, 3 H-misonidazole binding, and the paired survival curve assay of radiosensitivity. The hypoxic cell fraction of the tumors in mice breathing 10% oxygen was 3.1 times higher than that of tumors in mice breathing normal air determined by an in vivo-in vitro clonogenic assay. Binding of radiolabeled misonidazole to the tumors in mice breathing 10% oxygen was also significantly higher than that to tumors in mice breathing normal air (p 2 value for the tumor. The number of pO 2 readings lower than 5 mmHg in the tumor was not affected by the 10% oxygen breathing. These findings indicate that increases in radiobiological hypoxic fraction produced by lower blood oxygen levels may not correlate well with the results of polarographic measurements of tumor pO 2 levels. 29 refs., 4 figs., 1 tab

The influence of interleukin-2, feeder cells, and timing of irradiation on the radiosensitivity of human T lymphocytes assessed by the colony-forming assay

International Nuclear Information System (INIS)

Gerber, M.; Guichard, M.; Pioch, Y.; Dubois, J.B.

1989-01-01

The radiosensitivity of human lymphocytes was investigated by the method of colony formation in the absence of interleukin-2 (IL2) and feeder cells, both of which enhance growth of T-cell colonies. The shape of the survival curve and the radiosensitivity was shown to depend upon the ability of lymphocytes to produce IL2: the survival curve for lymphocytes that were the most competent producers of IL2 is the closest to linearity; the lymphocytes that were poor producers show biphasic survival curves. The radiosensitivity of the lymphocytes from the first group is less than that of the latter, when the comparison is based on the first part of the biphasic survival curve. This is more easily seen when cultures are irradiated 24 h after stimulation by phytohemagglutinin (the time of the peak IL2 production) than when cultures are irradiated 2 h before stimulation. This study demonstrates that growth conditions influence the response of lymphocytes to irradiation and that optimal growth conditions result in a linear survival curve

Competitive binding assay for fructose 2,6-bisphosphate

International Nuclear Information System (INIS)

Thomas, H.; Uyeda, K.

1986-01-01

A new direct assay method for fructose 2,6-bisphosphate has been developed based on competitive binding of labeled and unlabeled fructose 2,6-P 2 to phosphofructokinase. Phosphofructokinase (0.5-1.3 pmol promoter) is incubated with saturating concentrations (5.0-5.5 pmol) of fructose 2,6[2- 32 P]P 2 and samples containing varying concentrations of fructose 2,6-P 2 . The resulting stable binary complex is retained on nitrocellulose filters with a binding efficiency of up to 70%. Standard curves obtained with this assay show strict linearity with varying fructose 2,6-P 2 in the range of 0.5 to 45 pmol, which exceeds the sensitivity of most of the previously described assay methods. Fructose 2,6-P 2 , ATP, and high concentrations of phosphate interfere with this assay. However, the extent of this inhibition is negligible since their tissue contents are one-half to one-tenth that examined. The new assay is simple, direct, rapid, and does not require pretreatment

Methodology for determination of plasma cortisol in fish using Competitive Enzyme-Linked Immunosorbent Assay (ELISA)

DEFF Research Database (Denmark)

Velasco-Santamaría, Yohana M.; Cruz-Casallas, Pablo E.

2007-01-01

Objective. To determine plasma cortisol procedure in fish using competitive enzymelinked immunosorbent assay (ELISA). Materials and methods. Two plasma samples of juveniles rainbow trout Oncorhynchus mykiss were analized by using ELISA human kit for cortisol assay. For standard curve calibration...

Using commercial simulators for determining flash distillation curves for petroleum fractions

Directory of Open Access Journals (Sweden)

Eleonora Erdmann

2008-01-01

Full Text Available This work describes a new method for estimating the equilibrium flash vaporisation (EFV distillation curve for petro-leum fractions by using commercial simulators. A commercial simulator was used for implementing a stationary mo-del for flash distillation; this model was adjusted by using a distillation curve obtained from standard laboratory ana-lytical assays. Such curve can be one of many types (eg ASTM D86, D1160 or D2887 and involves an experimental procedure simpler than that required for obtaining an EFV curve. Any commercial simulator able to model petroleum can be used for the simulation (HYSYS and CHEMCAD simulators were used here. Several types of petroleum and fractions were experimentally analysed for evaluating the proposed method; this data was then put into a process si-mulator (according to the proposed method to estimate the corresponding EFV curves. HYSYS- and CHEMCAD-estimated curves were compared to those produced by two traditional estimation methods (Edmister’s and Maswell’s methods. Simulation-estimated curves were close to average Edmister and Maxwell curves in all cases. The propo-sed method has several advantages; it avoids the need for experimentally obtaining an EFV curve, it does not de-pend on the type of experimental curve used to fit the model and it enables estimating several pressures by using just one experimental curve as data.

Dose - Response Curves for Dicentrics and PCC Rings: Preparedness for Radiological Emergency in Thailand

International Nuclear Information System (INIS)

Rungsimaphorn, B.; Rerkamnuaychoke, B.; Sudprasert, W.

2014-01-01

Establishing in-vitro dose calibration curves is important for reconstruction of radiation dose in the exposed individuals. The aim of this pioneering work in Thailand was to generate dose-response curves using conventional biological dosimetry: dicentric chromosome assay (DCA) and premature chromosome condensation (PCC) assay. The peripheral blood lymphocytes were irradiated with 137 Cs at a dose rate of 0.652 Gy/min to doses of 0.1, 0.25, 0.5, 0.75, 1, 2, 3, 4 and 5 Gy for DCA technique, and 5, 10, 15, 20 and 25 Gy for PCC technique. The blood samples were cultured and processed following the standard procedure given by the IAEA with slight modifications. At least 500-1,000 metaphases or 100 dicentrics/ PCC rings were analyzed using an automated metaphase finder system. The yield of dicentrics with dose was fitted to a linear quadratic model using Chromosome Aberration Calculation Software (CABAS, version 2.0), whereas the dose-response curve of PCC rings was fitted to a linear relationship. These curves will be useful for in-vitro dose reconstruction and can support the preparedness for radiological emergency in the country.

The effect of melatonin on mouse jejunal crypt cell survival and apoptosis

International Nuclear Information System (INIS)

Kang, Jin Oh; Ha, Eun Young; Baik, Hyung Hwan; Cho, Yong Ho; Hong, Seong Eon

2000-01-01

To evaluate protective mechanism of melatonin against radiation damage and its relationship with apoptosis in mouse jejunum. 168 mice were divided into 28 groups according to radiation dose and melatonin treatment. To analysis crypt survival, microcolony survival assay was done according to Withers and Elkind's method. To analysis apoptosis, TUNEL assay was done according to Labet-Moleur's method. Radiation protection effect of melatonin was demonstrated by crypt survival assay and its effect was stronger in high radiation dose area. Apoptosis index with 8 Gy irradiation was 18.4% in control group and 16.5% in melatonin treated group. After 18 Gy, apoptosis index was 17.2%in control group and 15.4% in melatonin treated group. Apoptosis index did not show statistically significant difference between melatonin shows clear protective effect in mouse jejunum against radiation damage but its protective effect seems not to be related with apoptosis protection effect

Use of the micronucleus assay for the selective detection of radiosensitivity in BUdR-unincorporated cells after pulse-labelling of exponentially growing tumour cells

Energy Technology Data Exchange (ETDEWEB)

Masunaga, S.; Ono, K.; Fushiki, M.; Abe, M. (Kyoto Univ. (Japan). Faculty of Medicine); Wandl, E.O. (Vienna Univ. (Austria). Klinik fuer Strahlentherapie und Strahlenbiologie)

1990-08-01

To determine the radiosensitivity of non S-phase tumour cells in vitro, survival curves of SCC VII tumour cells were obtained after a short block with hydroxyurea. Dose-response curves of micronucleus (MN) frequency appearing in non-S-phase cells were also determined by excluding S-phase cells with immunofluorescence staining to 5-bromo-2'-deoxyuridine (BUdR). Both the dose response curves of MN frequency and survival curves were analysed by a linear-quadratic model (surviving fraction =exp (-{alpha}D-{beta}D{sup 2}), MN frequency =aD+bD{sup 2}+c). A good correlation between the {alpha}/{beta} and a/b ratios was observed. In both BUdR-unincorporated and asynchronous cell cultures, the regression lines between the surviving fraction and micronucleus frequency were statistically identical. (author).

Single-dose-response curves of murine gastrointestinal crypt stem cells

International Nuclear Information System (INIS)

Masuda, K.; Withers, H.R.; Mason, K.A.; Chen, K.Y.

1977-01-01

Dose-response curves for the reproductive capacity of crypt stem cells of murine colonic, jejunal, and gastric mucosae exposed in situ to multifractionated gamma ray exposures were analyzed and single-dose-survival curves of these cells were constructed. The following conclusions were drawn: (1) The single-dose-response curves bend downward over a dose range of approximately 200 to 1500 rad; (2) cell death seems to be due to nonrepairable damage at doses less than 250 rad for colon, and 220 rad for jejunum; (3) there are 21, 110, and 140 stem cells per crypt of gastric, colonic, and jejunal mucosa, respectively; and (4) jejunal stem cells are the most radiosensitive and gastric mucosal stem cells are the most resistant

Why the Kantian ideal survives medical learning curves, and why it matters.

Science.gov (United States)

Brecher, B

2006-09-01

The "Kantian ideal" is often misunderstood as invoking individual autonomy rather than rational self legislation. Le Morvan and Stock's otherwise insightful discussion of "Medical learning curves and the Kantian ideal"--for example--draws the mistaken inference that that ideal is inconsistent with the realities of medical practice. But it is not. Rationally to be a patient entails accepting its necessary conditions.

A radioreceptor assay for measurement of plasma glucocorticoid binding activity

International Nuclear Information System (INIS)

Fan Jie

1990-01-01

A radioreceptor assay (RRA) for plasma glucocorticoid binding activity (GCBA) has been developed using glucocorticoid receptor in rat thymocytes. Unlike other assays for natural and certain synthetic corticosteroids, RRA measures the GCBA of all natural and synthetic GC in plasma. The range of standard curve was 0 ∼ 1.00 mg/L. The sensitivity was 0.01 mg/l. The recovery rate was 92.1%, and the intra and inter assay CV was 0.7% (n = 3) and 4.4% (n = 3) respectively. The level of corticosterone in 9 rat plasma samples was determined by RRA and CBG-isotope binding assay. There was a general correlation over a wide range between the values determined by the two assays (r = 0.95; P < 0.001). The measuring condition was described in detail

Adjuvant Medications That Improve Survival after Locoregional Therapy.

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Boas, F Edward; Ziv, Etay; Yarmohammadi, Hooman; Brown, Karen T; Erinjeri, Joseph P; Sofocleous, Constantinos T; Harding, James J; Solomon, Stephen B

2017-07-01

To determine if outpatient medications taken at the time of liver tumor embolization or ablation affect survival. A retrospective review was done of 2,032 liver tumor embolization, radioembolization, and ablation procedures performed in 1,092 patients from June 2009 to April 2016. Pathology, hepatocellular carcinoma (HCC) stage (American Joint Committee on Cancer), neuroendocrine tumor (NET) grade, initial locoregional therapy, overall survival after initial locoregional therapy, Child-Pugh score, Eastern Cooperative Oncology Group performance status, Charlson Comorbidity Index, and outpatient medications taken at the time of locoregional therapy were analyzed for each patient. Kaplan-Meier survival curves were calculated for patients taking 29 medications or medication classes (including prescription and nonprescription medications) for reasons unrelated to their primary cancer diagnosis. Kaplan-Meier curves were compared using the log-rank test. For patients with HCC initially treated with embolization (n = 304 patients), the following medications were associated with improved survival when taken at the time of embolization: beta-blockers (P = .0007), aspirin (P = .0008) and other nonsteroidal antiinflammatory drugs (P = .009), proton pump inhibitors (P = .004), and antivirals for hepatitis B or C (P = .01). For colorectal liver metastases initially treated with ablation (n = 172 patients), beta-blockers were associated with improved survival when taken at the time of ablation (P = .02). Aspirin and beta-blockers are associated with significantly improved survival when taken at the time of embolization for HCC. Aspirin was not associated with survival differences after locoregional therapy for NET or colorectal liver metastases, suggesting an HCC-specific effect. Copyright © 2017 SIR. Published by Elsevier Inc. All rights reserved.

Probabilistic evaluation of design S-N curve and reliability assessment of ASME code-based evaluation

International Nuclear Information System (INIS)

Zhao Yongxiang

1999-01-01

A probabilistic evaluating approach of design S-N curve and a reliability assessment approach of the ASME code-based evaluation are presented on the basis of Langer S-N model-based P-S-N curves. The P-S-N curves are estimated by a so-called general maximum likelihood method. This method can be applied to deal with the virtual stress amplitude-crack initial life data which have a characteristics of double random variables. Investigation of a set of the virtual stress amplitude-crack initial life (S-N) data of 1Cr18Ni9Ti austenitic stainless steel-welded joint reveals that the P-S-N curves can give a good prediction of scatter regularity of the S-N data. Probabilistic evaluation of the design S-N curve with 0.9999 survival probability has considered various uncertainties, besides of the scatter of the S-N data, to an appropriate extent. The ASME code-based evaluation with 20 reduction factor on the mean life is much more conservative than that with 2 reduction factor on the stress amplitude. Evaluation of the latter in 666.61 MPa virtual stress amplitude is equivalent to 0.999522 survival probability and in 2092.18 MPa virtual stress amplitude equivalent to 0.9999999995 survival probability. This means that the evaluation in the low loading level may be non-conservative and in contrast, too conservative in the high loading level. Cause is that the reduction factors are constants and the factors can not take into account the general observation that scatter of the N data increases with the loading level decreasing. This has indicated that it is necessary to apply the probabilistic approach to the evaluation of design S-N curve

Radiometric assays for glycerol, glucose, and glycogen

International Nuclear Information System (INIS)

Bradley, D.C.; Kaslow, H.R.

1989-01-01

We have developed radiometric assays for small quantities of glycerol, glucose and glycogen, based on a technique described by Thorner and Paulus for the measurement of glycerokinase activity. In the glycerol assay, glycerol is phosphorylated with [32P]ATP and glycerokinase, residual [32P]ATP is hydrolyzed by heating in acid, and free [32P]phosphate is removed by precipitation with ammonium molybdate and triethylamine. Standard dose-response curves were linear from 50 to 3000 pmol glycerol with less than 3% SD in triplicate measurements. Of the substances tested for interference, only dihydroxyacetone gave a slight false positive signal at high concentration. When used to measure glycerol concentrations in serum and in media from incubated adipose tissue, the radiometric glycerol assay correlated well with a commonly used spectrophotometric assay. The radiometric glucose assay is similar to the glycerol assay, except that glucokinase is used instead of glycerokinase. Dose response was linear from 5 to 3000 pmol glucose with less than 3% SD in triplicate measurements. Glucosamine and N-acetylglucosamine gave false positive signals when equimolar to glucose. When glucose concentrations in serum were measured, the radiometric glucose assay agreed well with hexokinase/glucose-6-phosphate dehydrogenase (H/GDH)-based and glucose oxidase/H2O2-based glucose assays. The radiometric method for glycogen measurement incorporates previously described isolation and digestion techniques, followed by the radiometric assay of free glucose. When used to measure glycogen in mouse epididymal fat pads, the radiometric glycogen assay correlated well with the H/GDH-based glycogen assay. All three radiometric assays offer several practical advantages over spectral assays

Study on quantification of HBs-antibody by immunoradiometric assay

International Nuclear Information System (INIS)

Kondo, Yuichi; Itoi, Yoshihiro; Kajiyama, Shizuo

1989-01-01

Quantification of HBs-antibody assay was carried out using a commercialized assay kit and standard solutions of HBs-antibody recognised as 1 st reference preparation of hepatitis B immunogloblin by WHO. Standard curve of HBs-antibody was drawn with the function of 3D-spline and the correlation factor was obtained as r = 0.999. Coefficient of intra-assay variance was 3.8 % and that of inter-assay variance was 7.8 %. Dilution tests showed satisfactory results in the range of 2-16 times. Correlation between value of cut-off indices and concentration of HBs-antibody was obtained as the formula of y = 2.599 x-3.894 (r = 0.992) and 2.1 of cut-off index corresponded to about 5 mIU/ml of HBs-antibody concentration. (author)

Technical report. The application of probability-generating functions to linear-quadratic radiation survival curves.

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Kendal, W S

2000-04-01

To illustrate how probability-generating functions (PGFs) can be employed to derive a simple probabilistic model for clonogenic survival after exposure to ionizing irradiation. Both repairable and irreparable radiation damage to DNA were assumed to occur by independent (Poisson) processes, at intensities proportional to the irradiation dose. Also, repairable damage was assumed to be either repaired or further (lethally) injured according to a third (Bernoulli) process, with the probability of lethal conversion being directly proportional to dose. Using the algebra of PGFs, these three processes were combined to yield a composite PGF that described the distribution of lethal DNA lesions in irradiated cells. The composite PGF characterized a Poisson distribution with mean, chiD+betaD2, where D was dose and alpha and beta were radiobiological constants. This distribution yielded the conventional linear-quadratic survival equation. To test the composite model, the derived distribution was used to predict the frequencies of multiple chromosomal aberrations in irradiated human lymphocytes. The predictions agreed well with observation. This probabilistic model was consistent with single-hit mechanisms, but it was not consistent with binary misrepair mechanisms. A stochastic model for radiation survival has been constructed from elementary PGFs that exactly yields the linear-quadratic relationship. This approach can be used to investigate other simple probabilistic survival models.

Rapid Simultaneous Amplification and Detection of the MBR/JH Chromosomal Translocation by Fluorescence Melting Curve Analysis

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Bohling, Sandra D.; King, Thomas C.; Wittwer, Carl T.; Elenitoba-Johnson, Kojo S. J.

1999-01-01

Polymerase chain reaction (PCR) amplification and product analysis for the detection of chromosomal translocations, such as the t(14;18), has traditionally been a two-step process. PCR product detection has generally entailed gel electrophoresis and/or hybridization or sequencing for confirmation of assay specificity. Using a microvolume fluorimeter integrated with a thermal cycler and a PCR-compatible double-stranded DNA (dsDNA) binding fluorescent dye (SYBR Green I), we investigated the feasibility of simultaneous thermal amplification and detection of MBR/JH translocation products by fluorescence melting curve analysis. We analyzed DNA from 30 cases of lymphoproliferative disorders comprising 19 cases of previously documented MBR/JH-positive follicle center lymphoma and 11 reactive lymphadenopathies. The samples were coded and analyzed blindly for the presence of MBR/JH translocations by fluorescence melting curve analysis. We also performed dilutional assays using the MBR/JH-positive cell line SUDHL-6. Multiplex PCR for MBR/JH and β-globin was used to simultaneously assess sample adequacy. All (100%) of the 19 cases previously determined to be MBR/JH positive by conventional PCR analysis showed a characteristic sharp decrease in fluorescence at ∼90°C by melting curve analysis after amplification. Fluorescence melting peaks obtained by plotting the negative derivative of fluorescence over temperature (−dF/dT) versus temperature (T) showed melting temperatures (Tm) at 88.85 ± 1.15°C. In addition, multiplex assays using both MBR/JH and β-globin primers yielded easily distinguishable fluorescence melting peaks at ∼90°C and 81.2°C, respectively. Dilutional assays revealed that fluorescence melting curve analysis was more sensitive than conventional PCR and agarose gel electrophoresis with ultraviolet transillumination by as much as 100-fold. Simultaneous amplification and fluorescence melting curve analysis is a simple, reliable, and sensitive method

Prognostic classification index in Iranian colorectal cancer patients: Survival tree analysis

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Amal Saki Malehi

2016-01-01

Full Text Available Aims: The aim of this study was to determine the prognostic index for separating homogenous subgroups in colorectal cancer (CRC patients based on clinicopathological characteristics using survival tree analysis. Methods: The current study was conducted at the Research Center of Gastroenterology and Liver Disease, Shahid Beheshti Medical University in Tehran, between January 2004 and January 2009. A total of 739 patients who already have been diagnosed with CRC based on pathologic report were enrolled. The data included demographic and clinical-pathological characteristic of patients. Tree-structured survival analysis based on a recursive partitioning algorithm was implemented to evaluate prognostic factors. The probability curves were calculated according to the Kaplan-Meier method, and the hazard ratio was estimated as an interest effect size. Result: There were 526 males (71.2% of these patients. The mean survival time (from diagnosis time was 42.46± (3.4. Survival tree identified three variables as main prognostic factors and based on their four prognostic subgroups was constructed. The log-rank test showed good separation of survival curves. Patients with Stage I-IIIA and treated with surgery as the first treatment showed low risk (median = 34 months whereas patients with stage IIIB, IV, and more than 68 years have the worse survival outcome (median = 9.5 months. Conclusion: Constructing the prognostic classification index via survival tree can aid the researchers to assess interaction between clinical variables and determining the cumulative effect of these variables on survival outcome.

Analysis of HIV using a high resolution melting (HRM) diversity assay: automation of HRM data analysis enhances the utility of the assay for analysis of HIV incidence.

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Cousins, Matthew M; Swan, David; Magaret, Craig A; Hoover, Donald R; Eshleman, Susan H

2012-01-01

HIV diversity may be a useful biomarker for discriminating between recent and non-recent HIV infection. The high resolution melting (HRM) diversity assay was developed to quantify HIV diversity in viral populations without sequencing. In this assay, HIV diversity is expressed as a single numeric HRM score that represents the width of a melting peak. HRM scores are highly associated with diversity measures obtained with next generation sequencing. In this report, a software package, the HRM Diversity Assay Analysis Tool (DivMelt), was developed to automate calculation of HRM scores from melting curve data. DivMelt uses computational algorithms to calculate HRM scores by identifying the start (T1) and end (T2) melting temperatures for a DNA sample and subtracting them (T2 - T1 =  HRM score). DivMelt contains many user-supplied analysis parameters to allow analyses to be tailored to different contexts. DivMelt analysis options were optimized to discriminate between recent and non-recent HIV infection and to maximize HRM score reproducibility. HRM scores calculated using DivMelt were compared to HRM scores obtained using a manual method that is based on visual inspection of DNA melting curves. HRM scores generated with DivMelt agreed with manually generated HRM scores obtained from the same DNA melting data. Optimal parameters for discriminating between recent and non-recent HIV infection were identified. DivMelt provided greater discrimination between recent and non-recent HIV infection than the manual method. DivMelt provides a rapid, accurate method of determining HRM scores from melting curve data, facilitating use of the HRM diversity assay for large-scale studies.

Starvation-survival of subsurface bacteria

International Nuclear Information System (INIS)

Magill, N.G.

1988-01-01

The ability of four subsurface isolates to survive starvation was examined and the results were compared to survival curves obtained for Escherichia coli B and Serratia marcescens. To examine the starvation-survival phenomenon further, several experimental parameters including nutritional history, initial cell density, growth phase, temperature of growth and starvation, and aeration. Nutritional history, initial cell density, and growth phases of the cells had some effect on the ability of these bacteria to survive whereas temperature and limited aeration had no effect under the conditions tested. No conditions were found where E. coli B or Serratia marcescens died rapidly or where less than 10% of the original cell number of viable cells remained. Because the apparent survival of these bacteria may be due to cryptic growth, cross-feeding experiments with 14 C-labeled cells and unlabeled cells were carried out with E. coli B and Pseudomonas Lula V. Leaked extracellular 14 C-compounds were not used for growth or maintenance energy, and were not taken up by either bacterium. Cryptic growth did not occur; the cells were truly starving under the experimental conditions used

A comparison of PCR assays for beak and feather disease virus and high resolution melt (HRM) curve analysis of replicase associated protein and capsid genes.

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Das, Shubhagata; Sarker, Subir; Ghorashi, Seyed Ali; Forwood, Jade K; Raidal, Shane R

2016-11-01

Beak and feather disease virus (BFDV) threatens a wide range of endangered psittacine birds worldwide. In this study, we assessed a novel PCR assay and genetic screening method using high-resolution melt (HRM) curve analysis for BFDV targeting the capsid (Cap) gene (HRM-Cap) alongside conventional PCR detection as well as a PCR method that targets a much smaller fragment of the virus genome in the replicase initiator protein (Rep) gene (HRM-Rep). Limits of detection, sensitivity, specificity and discriminatory power for differentiating BFDV sequences were compared. HRM-Cap had a high positive predictive value and could readily differentiate between a reference genotype and 17 other diverse BFDV genomes with more discriminatory power (genotype confidence percentage) than HRM-Rep. Melt curve profiles generated by HRM-Cap correlated with unique DNA sequence profiles for each individual test genome. The limit of detection of HRM-Cap was lower (2×10 -5 ng/reaction or 48 viral copies) than that for both HRM-Rep and conventional BFDV PCR which had similar sensitivity (2×10 -6 ng or 13 viral copies/reaction). However, when used in a diagnostic setting with 348 clinical samples there was strong agreement between HRM-Cap and conventional PCR (kappa=0.87, PHRM-Cap demonstrated higher specificity (99.9%) than HRM-Rep (80.3%). Copyright © 2016 Elsevier B.V. All rights reserved.

Analytical performances of the Diazyme ADA assay on the Cobas® 6000 system.

Science.gov (United States)

Delacour, Hervé; Sauvanet, Christophe; Ceppa, Franck; Burnat, Pascal

2010-12-01

To evaluate the analytical performance of the Diazyme ADA assay on the Cobas® 6000 system for pleural fluid samples analysis. Imprecision, linearity, calibration curve stability, interference, and correlation studies were completed. The Diazyme ADA assay demonstrated excellent precision (CVADA assay correlated well with the Giusti method (r(2)=0.93) but exhibited a negative bias (~ -30%). The Diazyme ADA assay on the Cobas® 6000 system represents a rapid, accurate, precise and reliable method for determination of ADA activity in pleural fluid samples. Copyright © 2010 The Canadian Society of Clinical Chemists. Published by Elsevier Inc. All rights reserved.

[Comparative evaluation of survival prognosis using MELD or Child-Pugh scores in patients with liver cirrhosis in Chile].

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Sanhueza, Edgar; Contreras, Jorge; Zapata, Rodrigo; Sanhueza, Matías; Elgueta, Fabián; López, Constanza; Jerez, Sigrid; Jerez, Verónica; Delgado, Iris

2017-01-01

Currently, most liver units use the Child-Pugh (CP) or the Model for End-Stage Liver Disease (MELD) scores to establish survival prognosis among patients with liver cirrhosis. Which classification is superior, is not well defined. To compare CP and MELD classification scores to predict survival among adult patients with liver cirrhosis in Chile. Follow-up of 137 consecutive adult patients with liver cirrhosis aged 59 ± 12 years (55% women). The diagnosis was reached by clinical, laboratory and image studies at three different centers of Santiago. Patients were staged with CP and MELD classification scores at baseline and followed over a period of 12 months. The predictive capacity of the scores for survival was analyzed using a multivariate statistical analysis (Kaplan-Meier curves). The most common etiology was alcohol (37.9%). The actuarial survival rate was 79.6% at 12 months of follow-up. When comparing groups with areas under curve of receiver operating characteristic curves (AUROC), there was no statistically significant difference in survival between less severe and advanced disease, assessed with both survival scales. The AUROC for MELD and CP were 0.80 and 0.81, respectively. This clinical study did not find a statistically significant difference between the two classifications for the prediction of 12 months survival in patients with cirrhosis.

Dose-rate dependent stochastic effects in radiation cell-survival models

International Nuclear Information System (INIS)

Sachs, R.K.; Hlatky, L.R.

1990-01-01

When cells are subjected to ionizing radiation the specific energy rate (microscopic analog of dose-rate) varies from cell to cell. Within one cell, this rate fluctuates during the course of time; a crossing of a sensitive cellular site by a high energy charged particle produces many ionizations almost simultaneously, but during the interval between events no ionizations occur. In any cell-survival model one can incorporate the effect of such fluctuations without changing the basic biological assumptions. Using stochastic differential equations and Monte Carlo methods to take into account stochastic effects we calculated the dose-survival rfelationships in a number of current cell survival models. Some of the models assume quadratic misrepair; others assume saturable repair enzyme systems. It was found that a significant effect of random fluctuations is to decrease the theoretically predicted amount of dose-rate sparing. In the limit of low dose-rates neglecting the stochastic nature of specific energy rates often leads to qualitatively misleading results by overestimating the surviving fraction drastically. In the opposite limit of acute irradiation, analyzing the fluctuations in rates merely amounts to analyzing fluctuations in total specific energy via the usual microdosimetric specific energy distribution function, and neglecting fluctuations usually underestimates the surviving fraction. The Monte Carlo methods interpolate systematically between the low dose-rate and high dose-rate limits. As in other approaches, the slope of the survival curve at low dose-rates is virtually independent of dose and equals the initial slope of the survival curve for acute radiation. (orig.)

Lagrangian Curves on Spectral Curves of Monopoles

International Nuclear Information System (INIS)

Guilfoyle, Brendan; Khalid, Madeeha; Ramon Mari, Jose J.

2010-01-01

We study Lagrangian points on smooth holomorphic curves in TP 1 equipped with a natural neutral Kaehler structure, and prove that they must form real curves. By virtue of the identification of TP 1 with the space LE 3 of oriented affine lines in Euclidean 3-space, these Lagrangian curves give rise to ruled surfaces in E 3 , which we prove have zero Gauss curvature. Each ruled surface is shown to be the tangent lines to a curve in E 3 , called the edge of regression of the ruled surface. We give an alternative characterization of these curves as the points in E 3 where the number of oriented lines in the complex curve Σ that pass through the point is less than the degree of Σ. We then apply these results to the spectral curves of certain monopoles and construct the ruled surfaces and edges of regression generated by the Lagrangian curves.

Comet assay optimization for assessment of DNA damage due to radiation exposure

International Nuclear Information System (INIS)

Dwi Ramadhani; Devita Tetriana; Viria Agesti Suvifan

2016-01-01

Comet assay can be used to measure the deoxyribonucleic acid (DNA) damage level caused by ionizing radiation exposure in peripheral blood lymphocytes. The principle of the comet assay is based on the amount of denatured DNA fragments that migrated out of the cell nucleus during electrophoresis. There are several aspects that must be concerned when doing the comet assay. For example the agarose concentration, duration of alkaline incubation, electrophoresis conditions (time, temperature, and voltage gradient), and the measurement parameters that used in analyze the comet. Percentage of DNA in the comet tail (% tail DNA) is strongly recommended as a parameter when analyze the comet because it can be converted to lesions per 106 base pairs (bp) using calibration curve that show relationship between the dose of ionizing radiation and % tail DNA. To obtain an accurate result, the calibration curve must be made and comet should be analyzing using image processing analysis software since it can be increase the precision and reduce the subjectivity of the measurement process. (author)

High resolution melt curve analysis based on methylation status for human semen identification.

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Fachet, Caitlyn; Quarino, Lawrence; Karnas, K Joy

2017-03-01

A high resolution melt curve assay to differentiate semen from blood, saliva, urine, and vaginal fluid based on methylation status at the Dapper Isoform 1 (DACT1) gene was developed. Stains made from blood, saliva, urine, semen, and vaginal fluid were obtained from volunteers and DNA was isolated using either organic extraction (saliva, urine, and vaginal fluid) or Chelex ® 100 extraction (blood and semen). Extracts were then subjected to bisulfite modification in order to convert unmethylated cytosines to uracil, consequently creating sequences whose amplicons have melt curves that vary depending on their initial methylation status. When primers designed to amplify the promoter region of the DACT1 gene were used, DNA from semen samples was distinguishable from other fluids by a having a statistically significant lower melting temperature. The assay was found to be sperm-significant since semen from a vasectomized man produced a melting temperature similar to the non-semen body fluids. Blood and semen stains stored up to 5 months and tested at various intervals showed little variation in melt temperature indicating the methylation status was stable during the course of the study. The assay is a more viable method for forensic science practice than most molecular-based methods for body fluid stain identification since it is time efficient and utilizes instrumentation common to forensic biology laboratories. In addition, the assay is advantageous over traditional presumptive chemical methods for body fluid identification since results are confirmatory and the assay offers the possibility of multiplexing which may test for multiple body fluids simultaneously.

EL4 cell-based colorimetric toxin neutralization activity assays for determination of neutralizing anti-ricin antibodies.

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Lindsey, Changhong Y; Brown, J Edward; Torabazar, Nahid R; Smith, Leonard A

2013-01-01

A recombinant ricin toxin A-chain 1-33/44-198 vaccine (RVEc), developed at the United States Army Medical Research Institute of Infectious Diseases as a vaccine candidate, is under investigation in a phase 1 clinical study. To effectively evaluate the immunogenicity of this ricin vaccine and to eliminate the use of radioactive material, an EL4 cell-based colorimetric toxin neutralization activity (TNA) assay using a CellTiter 96 AQueous One Solution Cell Proliferation Assay Reagent has been developed, optimized, and applied in the vaccine efficacy studies. The TNA assay measures the protective neutralizing anti-ricin antibodies in animal sera by determining the cell viability after ricin exposure in the assay system and comparing it to a purified mouse polyclonal antiricin IgG standard curve. The standard curve of the anti-ricin TNA assay closely fits a four-parameter logistic regression model. The unknown test sample concentration was expressed as microg/mL, but not the 50% effective concentration (EC50), which was determined by most TNA assays. The neutralizing endpoint titers, not the 50% effective dilution (ED50), of human specimens were measured with the TNA assay in support of the clinical study of the RVEc vaccine. The optimal amount of ricin toxin, EL4 cells, and concentration of standards used in the assay system was established to minimize false-negative and false-positive results of serum specimens from the nonclinical and clinical studies of RVEc. The testing conditions were adjusted to optimize assay performance. The colorimetric TNA assay replaced a radioactive TNA assay previously used in the ricin vaccine studies.

A New Cytotoxicity Assay for Brevetoxins Using Fluorescence Microscopy

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Jennifer R. McCall

2014-09-01

Full Text Available Brevetoxins are a family of ladder-framed polyether toxins produced during blooms of the marine dinoflagellate, Karenia brevis. Consumption of shellfish or finfish exposed to brevetoxins can lead to the development of neurotoxic shellfish poisoning. The toxic effects of brevetoxins are believed to be due to the activation of voltage-sensitive sodium channels in cell membranes. The traditional cytotoxicity assay for detection of brevetoxins uses the Neuro-2A cell line, which must first be treated with the neurotoxins, ouabain and veratridine, in order to become sensitive to brevetoxins. In this study, we demonstrate several drawbacks of the Neuro-2A assay, which include variability for the EC50 values for brevetoxin and non-linear triphasic dose response curves. Ouabain/ veratridine-treated Neuro-2A cells do not show a typical sigmoidal dose response curve in response to brevetoxin, but rather, have a polynomial shaped curve, which makes calculating EC50 values highly variable. We describe a new fluorescence live cell imaging model, which allows for accurate calculation of cytotoxicity via nuclear staining and additional measurement of other viability parameters depending on which aspect of the cell is stained. In addition, the SJCRH30 cell line shows promise as an alternative to Neuro-2A cells for testing brevetoxins without the need for ouabain and veratridine.

In vivo survival of [14C]sucrose-loaded porcine carrier erythrocytes

International Nuclear Information System (INIS)

DeLoach, J.R.

1983-01-01

Porcine carrier erythrocyte survival was measured in adult pigs. [14C]Sucrose-loaded erythrocytes had a biphasic survival curve, with as much as 50% of the cells removed from circulation in the first 24 hours. The remaining cells had a 35-day half-life. Encapsulation values were measured for porcine erythrocytes and entrapment of [14C]sucrose was greater than 45%. Addition of inosine and glucose to the dialyzed cells and to the final wash buffer before reinjection of autologous cells did not improve their survival

Determination of PCBs in fish using enzyme-linked immunosorbent assay (ELISA)

Science.gov (United States)

Lasrado, J.A.; Santerre, C.R.; Zajicek, J.L.; Stahl, J.R.; Tillitt, D.E.; Deardorff, D.

2003-01-01

Polychlorinated biphenyls (PCBs) were determined in fish tissue using an enzyme-linked immunosorbent assay (ELISA). Standard curves for Aroclor 1248, 1254, and 1260 in catfish tissue were developed with ranges from 0.05 to 0.5 ppm and 0.5 to 5.0 ppm. Wild fish were initially analyzed using gas chromatography/electron-capture detection (GC/ECD) and those having residues within the standard curve ranges were analyzed with ELISA. Results obtained using ELISA and GC/ECD were not significantly different (p < 0.05) from 0.05 to 0.5 ppm. From 0.5 to 5.0 ppm, the standard curve for Aroclor 1254 was the best predictor of total PCB in wild fish samples.

Machine learning models in breast cancer survival prediction.

Science.gov (United States)

Montazeri, Mitra; Montazeri, Mohadeseh; Montazeri, Mahdieh; Beigzadeh, Amin

2016-01-01

Breast cancer is one of the most common cancers with a high mortality rate among women. With the early diagnosis of breast cancer survival will increase from 56% to more than 86%. Therefore, an accurate and reliable system is necessary for the early diagnosis of this cancer. The proposed model is the combination of rules and different machine learning techniques. Machine learning models can help physicians to reduce the number of false decisions. They try to exploit patterns and relationships among a large number of cases and predict the outcome of a disease using historical cases stored in datasets. The objective of this study is to propose a rule-based classification method with machine learning techniques for the prediction of different types of Breast cancer survival. We use a dataset with eight attributes that include the records of 900 patients in which 876 patients (97.3%) and 24 (2.7%) patients were females and males respectively. Naive Bayes (NB), Trees Random Forest (TRF), 1-Nearest Neighbor (1NN), AdaBoost (AD), Support Vector Machine (SVM), RBF Network (RBFN), and Multilayer Perceptron (MLP) machine learning techniques with 10-cross fold technique were used with the proposed model for the prediction of breast cancer survival. The performance of machine learning techniques were evaluated with accuracy, precision, sensitivity, specificity, and area under ROC curve. Out of 900 patients, 803 patients and 97 patients were alive and dead, respectively. In this study, Trees Random Forest (TRF) technique showed better results in comparison to other techniques (NB, 1NN, AD, SVM and RBFN, MLP). The accuracy, sensitivity and the area under ROC curve of TRF are 96%, 96%, 93%, respectively. However, 1NN machine learning technique provided poor performance (accuracy 91%, sensitivity 91% and area under ROC curve 78%). This study demonstrates that Trees Random Forest model (TRF) which is a rule-based classification model was the best model with the highest level of

High performance liquid chromatographic assay for the quantitation of total glutathione in plasma

Science.gov (United States)

Abukhalaf, Imad K.; Silvestrov, Natalia A.; Menter, Julian M.; von Deutsch, Daniel A.; Bayorh, Mohamed A.; Socci, Robin R.; Ganafa, Agaba A.

2002-01-01

A simple and widely used homocysteine HPLC procedure was applied for the HPLC identification and quantitation of glutathione in plasma. The method, which utilizes SBDF as a derivatizing agent utilizes only 50 microl of sample volume. Linear quantitative response curve was generated for glutathione over a concentration range of 0.3125-62.50 micromol/l. Linear regression analysis of the standard curve exhibited correlation coefficient of 0.999. Limit of detection (LOD) and limit of quantitation (LOQ) values were 5.0 and 15 pmol, respectively. Glutathione recovery using this method was nearly complete (above 96%). Intra-assay and inter-assay precision studies reflected a high level of reliability and reproducibility of the method. The applicability of the method for the quantitation of glutathione was demonstrated successfully using human and rat plasma samples.

Utility of Preoperative CA125 Assay in the Management Planning of Women Diagnosed with Uterine Cancer

Directory of Open Access Journals (Sweden)

N. Povolotskaya

2014-01-01

Full Text Available Objective. This study assesses the role of preoperative serum CA125 levels in the planning treatment options for women diagnosed with uterine cancer. Material and Method. Ninety five consecutive patients diagnosed with uterine cancer during a four-year period were identified. Age ranged from 35 to 89 years with a mean age of 69 years. The preoperative CA125 levels were dichotomised at 28 U/mL (using ROC analysis to identify the best discriminating threshold for 5-year survival. This level was then correlated with preoperative prognostic indicators: patient age, tumour grade, and histopathological tumour cell type. Survival data was plotted using Kaplan-Meier curves and analysed using the log-rank test. Univariate and multivariate analysis were performed to identify the predictors of overall survival. Results. The mean age of patients was 69 years (range: 35–89. On univariate analysis, the use of preoperative CA125 levels of greater or less than 28 U/mL correlated significantly with age (P=0.01, the grade of disease (P=0.02 and unfavourable tissue type (P=0.03. This threshold CA125 level had a sensitivity of 75%, specificity of 76%, positive predictive value of 35% and negative predicative value of 96.25%, and a likelihood ratio of 3.12 for predicting nodal disease. Using a threshold of preoperative CA125 level of 28 U/mL (area under curve: 0.60 was also a significant predictor of 5-year survival (log-rank test, P=0.01. Using Cox multivariate survival analysis to identify predictive preoperative factors overall, unfavourable cell type was the strongest predictor of survival (Chi square = 36.5, df = 4, and P=0.001, followed by preoperative CA125 level (CA125 > 28 U/mL, P=0.011 and unfavourable preoperative grade (P=0.017. Amongst patients with a favourable histological tissue type (endometrioid, preoperative CA125 levels predicted overall survival (Chi square = 6.039, df = 2, P=0.02; however unfavourable preoperative

Radiobiological and PK assays at advance Centre for Training Research and Education in Cancer (ACTREC)

International Nuclear Information System (INIS)

Sastri, Goda Jayant; Gota, Vikram

2014-01-01

Radiobiological, pharmacokinetic and biodistribution studies are of paramount importance for drug development and more so in the development of newer radiation modulators. Radiobiological studies have now graduated from simple cell survival and viability assays to more complex molecular and imaging studies to study radiation modulation both in in-vitro and in-vivo models. Tata Memorial Centre and its research centre (ACTREC) is a premiere cancer centre in India dedicated to cancer research. The Department of Radiation Oncology treats approximately 7000 new patients in a year and is uniquely placed to do both translational radiation and clinical research in the field of drug development. The Clinical Biology Lab of the Department of Radiation Oncology at ACTREC in collaboration with other labs at ACTREC has standardized cell survival assays, DNA damage assays such as Gamma H2AX assay (by flow as well as confocal microscopy), Micronuclei assay and COMET assays using CASP software for quantification. We have also done apoptotic assays. These assays have been conducted for development newer drug formulations (for e.g liposomal radiosensitizers). We also have a strong imaging division having sophisticated microscopes (confocal and single molecule super resolution microscopes) for in-vitro optical imaging and a dedicated preclinical PET/CT/SPECT for in-vivo imaging. The clinical 3T MRI and PET/CT is being used to study the effect of hypoxia in various cancers

Low-energy ED-XRF spectrometry application in gold assaying

International Nuclear Information System (INIS)

Marucco, Alessandra

2004-01-01

The performances of a low-energy dispersive XRF spectrometer in gold assaying are evaluated by a series of analysis on international standards and other certified gold alloys with. Results of standard-free analysis based on fundamental parameters method compared to results of multi-standard method, demonstrate a large gain of accuracy by drawing appropriate calibration curves with use of 1 to 16 matrix-specific standards. The accuracy of gold assaying has improved by a factor of 10, as compared to the conventional touchstone test. This rather economical technique satisfies then numerous precious alloys analyst needs, representing an excellent alternative to the traditional method for quick anti-fraud controls

LabKey Server NAb: A tool for analyzing, visualizing and sharing results from neutralizing antibody assays

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Gao Hongmei

2011-05-01

Full Text Available Abstract Background Multiple types of assays allow sensitive detection of virus-specific neutralizing antibodies. For example, the extent of antibody neutralization of HIV-1, SIV and SHIV can be measured in the TZM-bl cell line through the degree of luciferase reporter gene expression after infection. In the past, neutralization curves and titers for this standard assay have been calculated using an Excel macro. Updating all instances of such a macro with new techniques can be unwieldy and introduce non-uniformity across multi-lab teams. Using Excel also poses challenges in centrally storing, sharing and associating raw data files and results. Results We present LabKey Server's NAb tool for organizing, analyzing and securely sharing data, files and results for neutralizing antibody (NAb assays, including the luciferase-based TZM-bl NAb assay. The customizable tool supports high-throughput experiments and includes a graphical plate template designer, allowing researchers to quickly adapt calculations to new plate layouts. The tool calculates the percent neutralization for each serum dilution based on luminescence measurements, fits a range of neutralization curves to titration results and uses these curves to estimate the neutralizing antibody titers for benchmark dilutions. Results, curve visualizations and raw data files are stored in a database and shared through a secure, web-based interface. NAb results can be integrated with other data sources based on sample identifiers. It is simple to make results public after publication by updating folder security settings. Conclusions Standardized tools for analyzing, archiving and sharing assay results can improve the reproducibility, comparability and reliability of results obtained across many labs. LabKey Server and its NAb tool are freely available as open source software at http://www.labkey.com under the Apache 2.0 license. Many members of the HIV research community can also access the Lab

A pseudovirus-based hemagglutination-inhibition assay as a rapid, highly sensitive, and specific assay for detecting avian influenza A (H7N9 antibodies

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Anli Zhang

2015-06-01

Full Text Available Background Increased surveillance of avian-origin influenza A (H7N9 virus infection is critical to assess the risk of new outbreaks in China. A high-throughput assay with a good safety profile, sensitivity, and specificity is urgently needed. Methods We used a hemagglutination-inhibition (HI assay based on an H7N9-enveloped pseudovirus to assess serum neutralization antibodies level in 40 H7N9 positive sera and 40 H7N9 negative sera and compared the efficacy of the assay with traditional HI test and micro-neutralization (MN test. Results Spearman’s rank correlation coefficient analysis showed pseudovirus HI (PHI titers correlated well with both HI titers and MN titers. Receiver operating characteristic (ROC curves test revealed using a PHI cut-off titer of 10, the sensitivity and specificity reached 1.0. Conclusions PHI can be used in H7N9-related serological studies. This assay is high-throughput, very sensitive and specific, and cost effective.

Radiation survival of cells from spheroids grown in different oxygen concentrations

International Nuclear Information System (INIS)

Franko, A.J.; Sutherland, R.M.

1979-01-01

The position of the internal, chronically hypoxic cells in spheroids was varied by alterations in the oxygen concentration in the growth medium. Such alterations were expected to cause large changes in the size of the radiobiologically hypoxic fraction. This was tested by growing and irradiating spheroids in oxygen concentrations between 5 and 20.3%, ensuring that the irradiation and growth conditions were as similar as possible. The survival curves appeared to be linear below a surviving fraction of 3 x 10 -2 , and the slopes were intermediate between the slopes of control curves for cells from spheroids irradiated in nitrogen or when fully oxygenated. Thus direct estimates of the hypoxic fractions could not be made. Two models of oxygen diffusion might explain the data. One model assumes that a large fraction of cells was fully hypoxic (radiobiologically) and that these internal, G 1 -confined, chronically hypoxic cells had a lower inherent radioresistance than the outer proliferating cells. Evidence was presented which indicated that this model was unlikely to be correct. The other model assumes that the inherent radioresistance was equal throughout the spheroid, and that the innermost cells died before the oxygen concentration was reduced sufficiently to cause full hypoxic protection. Theoretical survival curves based on this model were generated using the measured geometries ofthe spheroids and multitarget single-hit survival theory. Acceptable agreement with the postulate that the innermost cells of spheroids die at between 0.2 and 0.4% oxygen was obtained. These data may have implications regarding the relative contributions of chronic and acute hypoxia to the fraction of hypoxic cells in tumors

Risk factors affecting survival in heart transplant patients.

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Almenar, L; Cardo, M L; Martínez-Dolz, L; García-Palomar, C; Rueda, J; Zorio, E; Arnau, M A; Osa, A; Palencia, M

2005-11-01

Certain cardiovascular risk factors have been linked to morbidity and mortality in heart transplant (HT) patients. The sum of various risk factors may have a large cumulative negative effect, leading to a substantially worse prognosis and the need to consider whether HT is contraindicated. The objective of this study was to determine whether the risk factors usually available prior to HT result in an excess mortality in our setting that contraindicates transplantation. Consecutive patients who underwent heart transplantation from November 1987 to January 2004 were included. Heart-lung transplants, retransplants, and pediatric transplants were excluded. Of the 384 patients, 89% were men. Mean age was 52 years (range, 12 to 67). Underlying disease included ischemic heart disease (52%), idiopathic dilated cardiomyopathy (36%), valvular disease (8%), and other (4%). Variables considered risk factors were obesity (BMI >25), dyslipidemia, hypertension, prior thoracic surgery, diabetes, and history of ischemic heart disease. Survival curves by number of risk factors using Kaplan-Meier and log-rank for comparison of curves. Overall patient survival at 1, 5, 10, and 13 years was 76%, 68%, 54%, and 47%, respectively. Survival at 10 years, if fewer than two risk factors were present, was 69%; 59% if two or three factors were present; and 37% if more than three associated risk factors were present (P = .04). The presence of certain risk factors in patients undergoing HT resulted in lower survival rates. The combination of various risk factors clearly worsened outcomes. However, we do not believe this should be an absolute contraindication for transplantation.

In vivo Comet assay--statistical analysis and power calculations of mice testicular cells.

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Hansen, Merete Kjær; Sharma, Anoop Kumar; Dybdahl, Marianne; Boberg, Julie; Kulahci, Murat

2014-11-01

The in vivo Comet assay is a sensitive method for evaluating DNA damage. A recurrent concern is how to analyze the data appropriately and efficiently. A popular approach is to summarize the raw data into a summary statistic prior to the statistical analysis. However, consensus on which summary statistic to use has yet to be reached. Another important consideration concerns the assessment of proper sample sizes in the design of Comet assay studies. This study aims to identify a statistic suitably summarizing the % tail DNA of mice testicular samples in Comet assay studies. A second aim is to provide curves for this statistic outlining the number of animals and gels to use. The current study was based on 11 compounds administered via oral gavage in three doses to male mice: CAS no. 110-26-9, CAS no. 512-56-1, CAS no. 111873-33-7, CAS no. 79-94-7, CAS no. 115-96-8, CAS no. 598-55-0, CAS no. 636-97-5, CAS no. 85-28-9, CAS no. 13674-87-8, CAS no. 43100-38-5 and CAS no. 60965-26-6. Testicular cells were examined using the alkaline version of the Comet assay and the DNA damage was quantified as % tail DNA using a fully automatic scoring system. From the raw data 23 summary statistics were examined. A linear mixed-effects model was fitted to the summarized data and the estimated variance components were used to generate power curves as a function of sample size. The statistic that most appropriately summarized the within-sample distributions was the median of the log-transformed data, as it most consistently conformed to the assumptions of the statistical model. Power curves for 1.5-, 2-, and 2.5-fold changes of the highest dose group compared to the control group when 50 and 100 cells were scored per gel are provided to aid in the design of future Comet assay studies on testicular cells. Copyright © 2014 Elsevier B.V. All rights reserved.

Survival of irradiated glia and glioma cells studied with a new cloning technique

International Nuclear Information System (INIS)

Nilsson, S.; Carlsson, J.; Larsson, B.; Ponten, J.

1980-01-01

A method allowing cloning of monolayer cultured cells with a low plating efficiency was developed. Cells were grown in several small palladium squares to obtain a high cell density. These squares were surrounded by non-adhesive agarose to prevent large distance migration and thereby mixing of the clones. By using easily-cloned hamster cells for comparison it was found that the survival curves were similar to the curves obtained with conventional cloning. The new method was used to compare the radiosensitivity of cultured human glia and glioma cells which both have a low plating efficiency ( 0 -values (1.5 to 2.5 Gy) and large shoulders (extrapolation numbers around 5) indicating that they were rather resistant and had a high capacity for accumulation of sublethal damage. The survival curves for glia cells had lower D 0 -values (1.3 to 1.5 Gy) and no shoulders at all, indicating that they were more sensitive than the glioma cells. (author)

Cell survival and radiation induced chromosome aberrations. Pt. 2

International Nuclear Information System (INIS)

Bauchinger, M.; Schmid, E.; Braselmann, H.

1986-01-01

Human peripheral lymphocytes were irradiated in whole blood with 0.5-4.0 Gy of 220 kVp X-rays and the frequency of chromosome aberrations was determined in 1st or 2nd division metaphases discriminated by fluorescence plus giemsa staining. Using the empirical distributions of aberrations among cells, cell survival and transmission of aberrations were investigated. Considering both daughter cells, we found that 20% of fragments and 55% of dicentrics or ring chromosomes are lost during the 1st cell division; i.e. cell survival rate from 1st to 2nd generation is mainly influenced by anaphase bridging of these two-hit aberrations. Cell survival to 2nd mitosis was calculated considering this situation and compared with the survival derived from the fraction of M1 cells without unstable aberrations. The resulting shouldered survival curves showed significantly different slopes, indicating that cell reproductive death is overestimated in the latter approach. (orig.)

Radioligand binding assay of cortisol using horse transcortin

International Nuclear Information System (INIS)

Dash, R.J.; Sharma, B.R.; Lata, V.

1979-01-01

A modified radioligand binding assay was developed to measure cortisol in a single methylene chloride extract of human plasma/serum. The assay utilises 5 percent horse serum for cortisol binding and 3 H-cortisol as tracer. Except for a cross reaction of 13.3 percent for cortisone and 7 percent for prednisolone that for other steroids tested was negligible. The assay sensitivity at the lower 95 percent inhibition of buffer controls was 20 pg/tube. The log dose logit response standard curve was linear between 80 pg and 5 ng/tube. Recovery(Y) of cortisol added (x) to male and pregnant female plasma was quantitated (y = 0.983 X-0.47, r = 0.98). Regression analysis of cortisol estimates obtained in 51 plasma/serum samples with this assay system and a specific radioimmunoassay (using cortisol-3-BSA antiserum) for plasma cortisol gave a coefficient of correlation (r) of 0.95 and a regression coefficient (b) of 0.97. The method was found to be simple and highly reproducible. Availability of all reagents in the aqueous phase permitted handling of a large number of samples by a single technician. (auth.)

Prognostic and survival analysis of presbyopia: The healthy twin study

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Lira, Adiyani; Sung, Joohon

2015-12-01

Presbyopia, a vision condition in which the eye loses its flexibility to focus on near objects, is part of ageing process which mostly perceptible in the early or mid 40s. It is well known that age is its major risk factor, while sex, alcohol, poor nutrition, ocular and systemic diseases are known as common risk factors. However, many other variables might influence the prognosis. Therefore in this paper we developed a prognostic model to estimate survival from presbyopia. 1645 participants which part of the Healthy Twin Study, a prospective cohort study that has recruited Korean adult twins and their family members based on a nation-wide registry at public health agencies since 2005, were collected and analyzed by univariate analysis as well as Cox proportional hazard model to reveal the prognostic factors for presbyopia while survival curves were calculated by Kaplan-Meier method. Besides age, sex, diabetes, and myopia; the proposed model shows that education level (especially engineering program) also contribute to the occurrence of presbyopia as well. Generally, at 47 years old, the chance of getting presbyopia becomes higher with the survival probability is less than 50%. Furthermore, our study shows that by stratifying the survival curve, MZ has shorter survival with average onset time about 45.8 compare to DZ and siblings with 47.5 years old. By providing factors that have more effects and mainly associate with presbyopia, we expect that we could help to design an intervention to control or delay its onset time.

Analysis of chromium-51 release assay data using personal computer spreadsheet software

International Nuclear Information System (INIS)

Lefor, A.T.; Steinberg, S.M.; Wiebke, E.A.

1988-01-01

The Chromium-51 release assay is a widely used technique to assess the lysis of labeled target cells in vitro. We have developed a simple technique to analyze data from Chromium-51 release assays using the widely available LOTUS 1-2-3 spreadsheet software. This package calculates percentage specific cytotoxicity and lytic units by linear regression. It uses all data points to compute the linear regression and can determine if there is a statistically significant difference between two lysis curves. The system is simple to use and easily modified, since its implementation requires neither knowledge of computer programming nor custom designed software. This package can help save considerable time when analyzing data from Chromium-51 release assays

[The survival prediction model of advanced gallbladder cancer based on Bayesian network: a multi-institutional study].

Science.gov (United States)

Tang, Z H; Geng, Z M; Chen, C; Si, S B; Cai, Z Q; Song, T Q; Gong, P; Jiang, L; Qiu, Y H; He, Y; Zhai, W L; Li, S P; Zhang, Y C; Yang, Y

2018-05-01

Objective: To investigate the clinical value of Bayesian network in predicting survival of patients with advanced gallbladder cancer(GBC)who underwent curative intent surgery. Methods: The clinical data of patients with advanced GBC who underwent curative intent surgery in 9 institutions from January 2010 to December 2015 were analyzed retrospectively.A median survival time model based on a tree augmented naïve Bayes algorithm was established by Bayesia Lab software.The survival time, number of metastatic lymph nodes(NMLN), T stage, pathological grade, margin, jaundice, liver invasion, age, sex and tumor morphology were included in this model.Confusion matrix, the receiver operating characteristic curve and area under the curve were used to evaluate the accuracy of the model.A priori statistical analysis of these 10 variables and a posterior analysis(survival time as the target variable, the remaining factors as the attribute variables)was performed.The importance rankings of each variable was calculated with the polymorphic Birnbaum importance calculation based on the posterior analysis results.The survival probability forecast table was constructed based on the top 4 prognosis factors. The survival curve was drawn by the Kaplan-Meier method, and differences in survival curves were compared using the Log-rank test. Results: A total of 316 patients were enrolled, including 109 males and 207 females.The ratio of male to female was 1.0∶1.9, the age was (62.0±10.8)years.There was 298 cases(94.3%) R0 resection and 18 cases(5.7%) R1 resection.T staging: 287 cases(90.8%) T3 and 29 cases(9.2%) T4.The median survival time(MST) was 23.77 months, and the 1, 3, 5-year survival rates were 67.4%, 40.8%, 32.0%, respectively.For the Bayesian model, the number of correctly predicted cases was 121(≤23.77 months) and 115(>23.77 months) respectively, leading to a 74.86% accuracy of this model.The prior probability of survival time was 0.503 2(≤23.77 months) and 0.496 8

Development of a Summarized Health Index (SHI for use in predicting survival in sea turtles.

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Tsung-Hsien Li

Full Text Available Veterinary care plays an influential role in sea turtle rehabilitation, especially in endangered species. Physiological characteristics, hematological and plasma biochemistry profiles, are useful references for clinical management in animals, especially when animals are during the convalescence period. In this study, these factors associated with sea turtle surviving were analyzed. The blood samples were collected when sea turtles remained alive, and then animals were followed up for surviving status. The results indicated that significantly negative correlation was found between buoyancy disorders (BD and sea turtle surviving (p < 0.05. Furthermore, non-surviving sea turtles had significantly higher levels of aspartate aminotranspherase (AST, creatinine kinase (CK, creatinine and uric acid (UA than surviving sea turtles (all p < 0.05. After further analysis by multiple logistic regression model, only factors of BD, creatinine and UA were included in the equation for calculating summarized health index (SHI for each individual. Through evaluation by receiver operating characteristic (ROC curve, the result indicated that the area under curve was 0.920 ± 0.037, and a cut-off SHI value of 2.5244 showed 80.0% sensitivity and 86.7% specificity in predicting survival. Therefore, the developed SHI could be a useful index to evaluate health status of sea turtles and to improve veterinary care at rehabilitation facilities.

An immunoenzymatic assay for the diagnosis of hepatitis A utilising immunoglobulin Y

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Alexandre dos Santos da Silva

2012-11-01

Full Text Available The detection of anti-hepatitis A virus (HAV antibody levels by diagnostic kits in the convalescent period of disease generally use immunoglobulin G (IgG, which is expensive. An alternative to IgG is immunoglobulin Y (IgY, an immunoglobulin antibody encountered in birds and reptiles. The aim of this study was to develop a competitive immunoenzymatic assay to measure total anti-HAV antibody levels using anti-HAV IgY as the capture and conjugated immunoglobulins. For this purpose, anti-HAV IgY was conjugated to horseradish peroxidase (HRP and the optimal dilution of HRP-conjugated antibodies was evaluated to establish the competitive immuneenzymatic assay. The results obtained from our "in-house" assay were plotted on a receiver operator curve, which showed a sensitivity of 95% and a specificity of 98.8%, demonstrating that a competitive anti-HAV IgY immunoenzymatic assay developed "in house" could be used as an alternative to commercial assays that utilise IgG.

Understanding survival analysis: Kaplan-Meier estimate.

Science.gov (United States)

Goel, Manish Kumar; Khanna, Pardeep; Kishore, Jugal

2010-10-01

Kaplan-Meier estimate is one of the best options to be used to measure the fraction of subjects living for a certain amount of time after treatment. In clinical trials or community trials, the effect of an intervention is assessed by measuring the number of subjects survived or saved after that intervention over a period of time. The time starting from a defined point to the occurrence of a given event, for example death is called as survival time and the analysis of group data as survival analysis. This can be affected by subjects under study that are uncooperative and refused to be remained in the study or when some of the subjects may not experience the event or death before the end of the study, although they would have experienced or died if observation continued, or we lose touch with them midway in the study. We label these situations as censored observations. The Kaplan-Meier estimate is the simplest way of computing the survival over time in spite of all these difficulties associated with subjects or situations. The survival curve can be created assuming various situations. It involves computing of probabilities of occurrence of event at a certain point of time and multiplying these successive probabilities by any earlier computed probabilities to get the final estimate. This can be calculated for two groups of subjects and also their statistical difference in the survivals. This can be used in Ayurveda research when they are comparing two drugs and looking for survival of subjects.

Effect of low fluencies of near-ultraviolet radiation on Bacteroides fragilis survival

International Nuclear Information System (INIS)

Slade, H.J.K.; Jones, D.T.; Woods, D.R.

1982-01-01

Bacteroides fragilis is a convenient obligate anaerobe for an investigation on the effect of near-UV irradiation since the authors have shown that it can be maintained in aerobic solutions for at least 6 h without loss in viability. Furthermore, they recently demonstrated that B. fragilis differs from other bacteria in that it is more sensitive to far-UV (254 nm) radiation in the presence of oxygen. The role of oxygen on near-UV survival in B. fragilis, was investigated. The effect of chloramphenicol was also studied. Survival curves are presented. B. fragilis Bf-2 cells irradiated with increasing fluencies of near-UV light under anaerobic conditions showed no loss in viability. A 'V'-shaped survival curve was obtained when cells were irradiated aerobically. After the initial reduction in viability with fluencies up to 1.5 kJ/m 2 further irradiation resulted in the recovery of colony-forming ability which was maximal at 2.6 kJ/m 2 and remained at this level up to fluencies of 4 kJ/m 2 . (Auth.)

A Quantitative Fluorescence-Based Lipase Assay

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Giovanna Lomolino

2012-01-01

Full Text Available An easy and fast gel diffusion assay for detecting and monitoring lipase activity by quantification of fluorescein is described. By measuring the intensity of fluorescein, it is possible to obtain a calibration curve with a regression coefficient better than by using the radius of fluorescent haloes. Through the quantification of fluorescence intensity of fluorescein released after the hydrolysis of a fluorescent ester, fluorescein dibutyrate, used as substrate in agar plates, commercial and skimmed milk lipase activity were studied. Moreover, with this method, lipase activity can be monitored in reaction medium that contains compounds which are affected by turbidity or cause measurement interference for UV-spectrophotometer and fluorimeter. In this experiment, boiled skimmed milk was dispersed in the agar gel with fluorescein dibutyrate, and it was used as a reaction medium to mimic natural conditions. The development of such an assay has a potential for applications in industries ranging from pharmaceuticals to food production and monitoring.

An HTRF® Assay for the Protein Kinase ATM.

Science.gov (United States)

Adams, Phillip; Clark, Jonathan; Hawdon, Simon; Hill, Jennifer; Plater, Andrew

2017-01-01

Ataxia telangiectasia mutated (ATM) is a serine/threonine kinase that plays a key role in the regulation of DNA damage pathways and checkpoint arrest. In recent years, there has been growing interest in ATM as a therapeutic target due to its association with cancer cell survival following genotoxic stress such as radio- and chemotherapy. Large-scale targeted drug screening campaigns have been hampered, however, by technical issues associated with the production of sufficient quantities of purified ATM and the availability of a suitable high-throughput assay. Using a purified, functionally active recombinant ATM and one of its physiological substrates, p53, we have developed an in vitro FRET-based activity assay that is suitable for high-throughput drug screening.

Comparison of monoclonal antibodies and tritiated ligands for estrogen receptor assays in 241 breast cancer cytosols

International Nuclear Information System (INIS)

Goussard, J.; Lechevrel, C.; Martin, P.M.; Roussel, G.

1986-01-01

Estrogen receptor determinations have been performed on 241 cytosols from 160 breast cancer tumors using both radioactive ligands ([ 3 H]-estradiol, [3H]R2858) and monoclonal antibodies (Abbott ER-EIA Kit) to compare the two methods and to evaluate the clinical usefulness of the new immunological, simplified assay. Intra- and interassay reproducibility of the enzyme immunoassay (EIA) method was studied during a 6-month period on 35 standard curves with 4 different batches of monoclonal antibodies. Intraassay coefficients of variation studied on duplicates were smaller than 5% in most cases and reproducibility of the curves showed coefficients of variation lower than 10% except for standard 0 and 5 fmol/ml. Pooled cytosols used as control for the dextran coated charcoal method had interassay variation coefficients between 3.8 and 11.4%. Reproducibility has been studied on clinical specimens assayed twice at two different periods with either EIA or dextran coated charcoal methods. Slopes obtained were 1.05 and 0.96, respectively. A good stability of EIA results was obtained with protein concentrations in the range 4-0.15 mg/ml cytosol. No significant effects of dithiothreitol or monothioglycerol (1 mM) on EIA and dextran coated charcoal assay were observed. Eighty breast cancer cytosols were assayed with both EIA and Scatchard analysis. The slope of the regression curve obtained was 1.04 (r = 0.963). Cytosols were assayed by EIA and by a saturating concentration of tritiated ligand (5 nM). With 153 cytosols the EIA/5 nM slope was 1.34 (r = 0.978). This slope can be compared with the slope Scatchard/5 nM obtained with 90 cytosols: 1.29 (r = 0.985). Absence of cross-reactivity of monoclonal ER antibodies with progesterone receptor was observed

Bioavailability of two oral formulations of triazolam using radioreceptor assay

Energy Technology Data Exchange (ETDEWEB)

Lapka, R; Cepelakova, H; Rejholec, V; Franc, Z

1986-04-01

The radioreceptor assay (RRA) was used to quantitate plasma triazolam concentration in eight female volunteers following single 0.5 mg doses of two tablet formulations in a cross-over study. Bioavailability in terms of area under the plasma concentration versus time curve, maximum plasma concentration, time to maximum, and mean residence time was not statistically significantly different from one formulation to the other.

ICECAP: an integrated, general-purpose, automation-assisted IC50/EC50 assay platform.

Science.gov (United States)

Li, Ming; Chou, Judy; King, Kristopher W; Jing, Jing; Wei, Dong; Yang, Liyu

2015-02-01

IC50 and EC50 values are commonly used to evaluate drug potency. Mass spectrometry (MS)-centric bioanalytical and biomarker labs are now conducting IC50/EC50 assays, which, if done manually, are tedious and error-prone. Existing bioanalytical sample preparation automation systems cannot meet IC50/EC50 assay throughput demand. A general-purpose, automation-assisted IC50/EC50 assay platform was developed to automate the calculations of spiking solutions and the matrix solutions preparation scheme, the actual spiking and matrix solutions preparations, as well as the flexible sample extraction procedures after incubation. In addition, the platform also automates the data extraction, nonlinear regression curve fitting, computation of IC50/EC50 values, graphing, and reporting. The automation-assisted IC50/EC50 assay platform can process the whole class of assays of varying assay conditions. In each run, the system can handle up to 32 compounds and up to 10 concentration levels per compound, and it greatly improves IC50/EC50 assay experimental productivity and data processing efficiency. © 2014 Society for Laboratory Automation and Screening.

Radiation cell survival and growth delay studies in multicellular spheroids of small-cell lung carcinoma

International Nuclear Information System (INIS)

Duchesne, G.M.; Peacock, J.H.

1987-01-01

The radiation sensitivity of two small-cell lung carcinoma cell lines growing as multicellular spheroids in static culture was determined using clonogenic cell survival and growth delay as endpoints. Growth delay determination suggested that clonogenic cell kill was less than was obtained by direct assay of cell survival. Recovery from potentially lethal damage was assayed in one line (HC12) but was not demonstrable, and clonogenic cell survival decreased with time in treated spheroids with diameters greater than 300 μm which contained a hypoxic cell population. Microscopic examination of the treated spheroids showed the emergence of an abnormal giant-cell population, and the progressive clonogenic cell loss that occurred after treatment was thought to be due to oxygen and nutrient deprivation of the remaining viable cells by this doomed cell population. Correction of the growth delay measurements for changes in cell size and clonogenic cell population allowed correlation of the growth delay and cell survival data. (author)

Tumor RNA disruption predicts survival benefit from breast cancer chemotherapy.

Science.gov (United States)

Parissenti, Amadeo M; Guo, Baoqing; Pritzker, Laura B; Pritzker, Kenneth P H; Wang, Xiaohui; Zhu, Mu; Shepherd, Lois E; Trudeau, Maureen E

2015-08-01

In a prior substudy of the CAN-NCIC-MA.22 clinical trial (ClinicalTrials.gov identifier NCT00066443), we observed that neoadjuvant chemotherapy reduced tumor RNA integrity in breast cancer patients, a phenomenon we term "RNA disruption." The purpose of the current study was to assess in the full patient cohort the relationship between mid-treatment tumor RNA disruption and both pCR post-treatment and, subsequently, disease-free survival (DFS) up to 108 months post-treatment. To meet these objectives, we developed the RNA disruption assay (RDA) to quantify RNA disruption and stratify it into 3 response zones of clinical importance. Zone 1 is a level of RNA disruption inadequate for pathologic complete response (pCR); Zone 2 is an intermediate level, while Zone 3 has high RNA disruption. The same RNA disruption cut points developed for pCR response were then utilized for DFS. Tumor RDA identified >fourfold more chemotherapy non-responders than did clinical response by calipers. pCR responders were clustered in RDA Zone 3, irrespective of tumor subtype. DFS was about 2-fold greater for patients with tumors in Zone 3 compared to Zone 1 patients. Kaplan-Meier survival curves corroborated these findings that high tumor RNA disruption was associated with increased DFS. DFS values for patients in zone 3 that did not achieve a pCR were similar to that of pCR recipients across tumor subtypes, including patients with hormone receptor positive tumors that seldom achieve a pCR. RDA appears superior to pCR as a chemotherapy response biomarker, supporting the prospect of its use in response-guided chemotherapy.

The survival effects of V79 cells irradiated with carbon ions in different let

International Nuclear Information System (INIS)

Wang Jufang; Zhou Guangming; He Jing; Li Wenjian; Li Qiang; Dang Bingrong; Li Xinglin; Weng Xiaoqiong; Xie Hongmei; Wei Zengquan; Gao Qingxiang

2001-01-01

The survival of cultured Chinese V79 hamster cells irradiated with carbon ions with different LETs were investigated. Irradiation was performed at the heavy Ion Research Facility in Lanzhou (HIRFL). Results were compared with those obtained from the experiments with γ rats and could be concluded as follows: The survival curves for carbon ions showed as straight lines and were fitted to the one-target one-hit model, but for γ rays the curves with shoulders were fitted to the multi-target one-hit model. As the LETs were 125, 200 and 700 keV/μm for carbon ions, the inactivation cross section 35, 12 and 8 μm 2 , respectively, which suggested that under the experimental conditions, the lower the LET of carbon ions, the more seriously the irradiation killed cells. In the case of 125 keV/μm, the RBEs of carbon ions at the 0.1 and 0.37 survival levels were 1.47 and 2.19 respectively

The effect of an asynchronous population of cells on the initial slope of dose-effect curves

International Nuclear Information System (INIS)

Chadwick, K.H.; Leenhouts, H.P.

1975-01-01

The molecular theory of cell survival gives an equation S = exp [ -p(αD + β D 2 )] which can be used to analyse dose-effect curves for synchronized cells. The variation in the coefficients α and β through the cell cycle has been found to be consistent for the different radiation types and is compatible with the induction of DNA double-strand breaks which is assumed in the theory to be the mechanism which is responsible for the biological effect. The theory predicts that low-LET radiation will have an initial slope, given by the coefficient α, and the consistency of the analysis of synchronized cell survival substantiates this prediction. In the molecular theory the induction of mutations has also been proposed to arise from DNA double-strand breaks and to be represented by the equation M = 1 - exp [-q(αD + β D 2 )]. This implies that at low doses of low-LET radiation the radiobiological effect will be linear with dose and that high-dose results may be analysed to provide estimates of the radiosensitivity of cells to low doses of radiation for radiological protection purposes. In an asynchronous population of cells it is possible that a small proportion of very radiosensitive cells can lead to significant deviations from this straightforward analysis. This 'Oftedal effect' is applied using the molecular theory to give a general theoretical relationship between the induction of mutations and cell survival. The theoretical relationship is compared with experimental data available from the literature. It is concluded that the initial slope of a mutation or cancer induction curve may be more relevant to the determination of the radiation sensitivity at low doses than the initial slope of a survival curve. (author)

Sequence Optimized Real-Time RT-PCR Assay for Detection of Crimean-Congo Hemorrhagic Fever Virus

Science.gov (United States)

2017-03-21

on the linear range of the curve 129 using a nonlinear regression analysis. A two-way ANOVA with Sidak’s multiple comparisons test was 130 done to...currently fielded CCHFV assay. 31 TR-17-094 DISTRIBUTION STATEMENT A: Approved for public release; distribution is unlimited. 2 Introduction 32...analyses were performed using GraphPrism 6 (GraphPad Software, San Diego, CA). 128 Assay linearity based on the preliminary LOD was determined based

Radiosensitivity of different human tumor cells lines grown as multicellular spheroids determined from growth curves and survival data

International Nuclear Information System (INIS)

Schwachoefer, J.H.C.; Crooijmans, R.P.; van Gasteren, J.J.; Hoogenhout, J.; Jerusalem, C.R.; Kal, H.B.; Theeuwes, A.G.

1989-01-01

Five human tumor cell lines were grown as multicellular tumor spheroids (MTS) to determine whether multicellular tumor spheroids derived from different types of tumors would show tumor-type dependent differences in response to single-dose irradiation, and whether these differences paralleled clinical behavior. Multicellular tumor spheroids of two neuroblastoma, one lung adenocarcinoma, one melanoma, and a squamous cell carcinoma of the oral tongue, were studied in terms of growth delay, calculated cell survival, and spheroid control dose50 (SCD50). Growth delay and cell survival analysis for the tumor cell lines showed sensitivities that correlated well with clinical behavior of the tumor types of origin. Similar to other studies on melanoma multicellular tumor spheroids our spheroid control dose50 results for the melanoma cell line deviated from the general pattern of sensitivity. This might be due to the location of surviving cells, which prohibits proliferation of surviving cells and hence growth of melanoma multicellular tumor spheroids. This study demonstrates that radiosensitivity of human tumor cell lines can be evaluated in terms of growth delay, calculated cell survival, and spheroid control dose50 when grown as multicellular tumor spheroids. The sensitivity established from these evaluations parallels clinical behavior, thus offering a unique tool for the in vitro analysis of human tumor radiosensitivity

Non-linear least squares curve fitting of a simple theoretical model to radioimmunoassay dose-response data using a mini-computer

International Nuclear Information System (INIS)

Wilkins, T.A.; Chadney, D.C.; Bryant, J.; Palmstroem, S.H.; Winder, R.L.

1977-01-01

Using the simple univalent antigen univalent-antibody equilibrium model the dose-response curve of a radioimmunoassay (RIA) may be expressed as a function of Y, X and the four physical parameters of the idealised system. A compact but powerful mini-computer program has been written in BASIC for rapid iterative non-linear least squares curve fitting and dose interpolation with this function. In its simplest form the program can be operated in an 8K byte mini-computer. The program has been extensively tested with data from 10 different assay systems (RIA and CPBA) for measurement of drugs and hormones ranging in molecular size from thyroxine to insulin. For each assay system the results have been analysed in terms of (a) curve fitting biases and (b) direct comparison with manual fitting. In all cases the quality of fitting was remarkably good in spite of the fact that the chemistry of each system departed significantly from one or more of the assumptions implicit in the model used. A mathematical analysis of departures from the model's principal assumption has provided an explanation for this somewhat unexpected observation. The essential features of this analysis are presented in this paper together with the statistical analyses of the performance of the program. From these and the results obtained to date in the routine quality control of these 10 assays, it is concluded that the method of curve fitting and dose interpolation presented in this paper is likely to be of general applicability. (orig.) [de

Plasma myelin basic protein assay using Gilford enzyme immunoassay cuvettes.

Science.gov (United States)

Groome, N P

1981-10-01

The assay of myelin basic protein in body fluids has potential clinical importance as a routine indicator of demyelination. Preliminary details of a competitive enzyme immunoassay for this protein have previously been published by the author (Groome, N. P. (1980) J. Neurochem. 35, 1409-1417). The present paper now describes the adaptation of this assay for use on human plasma and various aspects of routine data processing. A commercially available cuvette system was found to have advantages over microtitre plates but required a permuted arrangement of sample replicates for consistent results. For dose interpolation, the standard curve could be fitted to a three parameter non-linear equation by regression analysis or linearised by the logit/log transformation.

Effect of cadmium, lead and arsenic on the oviposition, hatching and embryonic survival of Biomphalaria glabrata

International Nuclear Information System (INIS)

Ansaldo, Martin; Nahabedian, Daniel E.; Di Fonzo, Carla; Wider, Eva A.

2009-01-01

Biomphalaria glabrata is a widespread freshwater gastropod mollusc. The easy aquaculture of these organisms allow its use as an accessible tool for contamination bioassays. B. glabrata showed marked metabolic responses when exposed to cadmium, lead and arsenic. Those responses could also affect the reproduction of the snails. Taking into account this hypothesis, B. glabrata were exposed for 96 h (acute laboratory bioassays) to different concentrations of cadmium (0.1, 0.05 and 0 mg/L), lead (0.5, 0.1, 0.05 and 0 mg/L) and arsenic (0.5, 0.1, 0.05 and 0 mg/L). Snails were removed from the aquaria while eggs were left in the same contaminant concentrations. The effect of the assayed toxicants on snail reproduction was registered as the alterations of the total number of laid eggs (TNLE), hatching time and embryonic survival. At 0.10 mg/L cadmium significantly decreased the TNLE (p < 0.05) and no embryos survived. The lowest assayed level (0.05 mg/L) of cadmium, delayed the hatching time twice when it was compared with the control group (p < 0.01). Lead decreased the TNLE at 0.5 mg/L level (p < 0.01). The other assayed doses (0.05 and 0.10 mg/L) also decreased embryonic survival significantly (p < 0.05 and p < 0.01 respectively) and extended twice the time to hatching (p < 0.01). The 0.50 mg/L level killed all embryos. Arsenic at all studied concentrations decreased the TNLE (p < 0.05) while the hatching time was increased by 50%. Embryo survival only decreased at the highest level (0.5 mg/L) of arsenic assayed. In summary, the acute exposure (96 h) to cadmium lead and arsenic, altered the reproduction of B. glabrata, modifying the TNLE, hatching time and embryonic survival

Cellular radiosensitivity of small-cell lung cancer cell lines

International Nuclear Information System (INIS)

Krarup, Marianne; Poulsen, Hans Skovgaard; Spang-Thomsen, Mogens

1997-01-01

Purpose: The objective of this study was to determine the radiobiological characteristics of a panel of small-cell lung cancer (SCLC) cell lines by use of a clonogenic assay. In addition, we tested whether comparable results could be obtained by employing a growth extrapolation method based on the construction of continuous exponential growth curves. Methods and Materials: Fifteen SCLC cell lines were studied, applying a slightly modified clonogenic assay and a growth extrapolation method. A dose-survival curve was obtained for each experiment and used for calculating several survival parameters. The multitarget single hit model was applied to calculate the cellular radiosensitivity (D 0 ), the capacity for sublethal damage repair (D q ), and the extrapolation number (n). Values for α and β were determined from best-fit curves according to the linear-quadratic model and these values were applied to calculate the surviving fraction after 2-Gy irradiation (SF 2 ). Results: In our investigation, the extrapolation method proved to be inappropriate for the study of in vitro cellular radiosensitivity due to lack of reproducibility. The results obtained by the clonogenic assay showed that the cell lines studied were radiobiologically heterogeneous with no discrete features of the examined parameters including the repair capacity. Conclusion: The results indicate that SCLC tumors per se are not generally candidates for hyperfractionated radiotherapy

Interspecific in vitro assay for the chimera-forming ability of human pluripotent stem cells.

Science.gov (United States)

Masaki, Hideki; Kato-Itoh, Megumi; Umino, Ayumi; Sato, Hideyuki; Hamanaka, Sanae; Kobayashi, Toshihiro; Yamaguchi, Tomoyuki; Nishimura, Ken; Ohtaka, Manami; Nakanishi, Mahito; Nakauchi, Hiromitsu

2015-09-15

Functional assay limitations are an emerging issue in characterizing human pluripotent stem cells (PSCs). With rodent PSCs, chimera formation using pre-implantation embryos is the gold-standard assay of pluripotency (competence of progeny to differentiate into all three germ layers). In human PSCs (hPSCs), however, this can only be monitored via teratoma formation or in vitro differentiation, as ethical concerns preclude generation of human-human or human-animal chimeras. To circumvent this issue, we developed a functional assay utilizing interspecific blastocyst injection and in vitro culture (interspecies in vitro chimera assay) that enables the development and observation of embryos up to headfold stage. The assay uses mouse pre-implantation embryos and rat, monkey and human PSCs to create interspecies chimeras cultured in vitro to the early egg-cylinder stage. Intra- and interspecific chimera assays with rodent PSC lines were performed to confirm the consistency of results in vitro and in vivo. The behavior of chimeras developed in vitro appeared to recapitulate that of chimeras developed in vivo; that is, PSC-derived cells survived and were integrated into the epiblast of egg-cylinder-stage embryos. This indicates that the interspecific in vitro chimera assay is useful in evaluating the chimera-forming ability of rodent PSCs. However, when human induced PSCs (both conventional and naïve-like types) were injected into mouse embryos and cultured, some human cells survived but were segregated; unlike epiblast-stage rodent PSCs, they never integrated into the epiblast of egg-cylinder-stage embryos. These data suggest that the mouse-human interspecies in vitro chimera assay does not accurately reflect the early developmental potential/process of hPSCs. The use of evolutionarily more closely related species as host embryos might be necessary to evaluate the developmental potency of hPSCs. © 2015. Published by The Company of Biologists Ltd.

Measurement of immunoglobulin production by peripheral blood mononuclear cells in vitro using a solid-phase immunoradiometric assay

International Nuclear Information System (INIS)

Roffe, L.M.; Maini, R.N.; Cohen, M.L.; Meretey, K.

1981-01-01

A simple solid-phase immunoradiometric assay for IgG and IgM is described. Supernatants from lymphocyte cultures are incubated in microtitre plates which have been precoated with anti-IgG or anti-IgM. Subsequent binding of 125 I-labelled anti-immunoglobulin is measured and IgG and IgM in supernatants are estimated from the standard curve constructed for each assay. The assay is specific for human IgG and IgM, is able to detect nanogram amounts and offers advantages over other techniques for evaluating in vitro lymphocyte function. (Auth.)

Selection of donor platelets for alloimmunized patients using a platelet-associated IgG assay

International Nuclear Information System (INIS)

Myers, T.J.; Kim, B.K.; Steiner, M.; Baldini, M.G.

1981-01-01

A quantitative immunofluorescence platelet-associated immunoglobulin-G (PA-IgG) assay was used to detect alloimmunity to platelets in 8/12 multitransfused patients and to perform platelet crossmatching in the 8 alloimmunized patients. The correct separation of multitransfused patients into alloimmune and nonalloimmune groups was substantiated with chromium-51-labeled platelet survival studies. For 5 alloimmunized patients, compatible and incompatible donor platelets were demonstrated by PA-IgG crossmatching and were confirmed by platelet survival studies. With the other 3 alloimmunized patients, only Pa-IgG incompatible donor platelets were found. Survival studies with 5 of these incompatible donor platelets showed markedly reduced survival times on 4 occasions. Pa-IgG compatible donor platelets survived 3.5 to 8.7 days, while Pa-IgG incompatible platelets showed survival times of 0.1 to 2.4 days

Enzymatic assays for the diagnosis of bradykinin-dependent angioedema.

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Federica Defendi

Full Text Available BACKGROUND: The kinins (primarily bradykinin, BK represent the mediators responsible for local increase of vascular permeability in hereditary angioedema (HAE, HAE I-II associated with alterations of the SERPING1 gene and HAE with normal C1-Inhibitor function (HAE-nC1INH. Besides C1-Inhibitor function and concentration, no biological assay of kinin metabolism is actually available to help physicians for the diagnosis of angioedema (AE. We describe enzymatic tests on the plasma for diagnosis of BK-dependent AE. METHODS: The plasma amidase assays are performed using the Pro-Phe-Arg-p-nitroanilide peptide substrate to evaluate the spontaneous amidase activity and the proenzyme activation. We analyzed data of 872 patients presenting with BK-dependent AE or BK-unrelated diseases, compared to 303 controls. Anti-high MW kininogen (HK immunoblot was achieved to confirm HK cleavage in exemplary samples. Reproducibility, repeatability, limit of blank, limit of detection, precision, linearity and receiver operating characteristics (ROC were used to calculate the diagnostic performance of the assays. RESULTS: Spontaneous amidase activity was significantly increased in all BK-dependent AE, associated with the acute phase of disease in HAE-nC1INH, but preserved in BK-unrelated disorders. The increase of the amidase activity was associated to HK proteolysis, indicating its relevance to identify kininogenase activity. The oestrogens, known for precipitating AE episodes, were found as triggers of enzymatic activity. Calculations from ROC curves gave the optimum diagnostic cut-off for women (9.3 nmol⋅min(-1⋅mL(-1, area under curve [AUC] 92.1%, sensitivity 80.0%, and specificity 90.1% and for men (6.6 nmol·min(-1⋅mL(-1, AUC 91.0%, sensitivity 87.0% and specificity 81.2%. CONCLUSION: The amidase assay represents a diagnostic tool to help physicians in the decision to distinguish between BK-related and -unrelated AE.

Development and validation of a Luminex assay for detection of a predictive biomarker for PROSTVAC-VF therapy

Science.gov (United States)

Lucas, Julie L.; Tacheny, Erin A.; Ferris, Allison; Galusha, Michelle; Srivastava, Apurva K.; Ganguly, Aniruddha; Williams, P. Mickey; Sachs, Michael C.; Thurin, Magdalena; Tricoli, James V.; Ricker, Winnie; Gildersleeve, Jeffrey C.

2017-01-01

Cancer therapies can provide substantially improved survival in some patients while other seemingly similar patients receive little or no benefit. Strategies to identify patients likely to respond well to a given therapy could significantly improve health care outcomes by maximizing clinical benefits while reducing toxicities and adverse effects. Using a glycan microarray assay, we recently reported that pretreatment serum levels of IgM specific to blood group A trisaccharide (BG-Atri) correlate positively with overall survival of cancer patients on PROSTVAC-VF therapy. The results suggested anti-BG-Atri IgM measured prior to treatment could serve as a biomarker for identifying patients likely to benefit from PROSTVAC-VF. For continued development and clinical application of serum IgM specific to BG-Atri as a predictive biomarker, a clinical assay was needed. In this study, we developed and validated a Luminex-based clinical assay for measuring serum IgM specific to BG-Atri. IgM levels were measured with the Luminex assay and compared to levels measured using the microarray for 126 healthy individuals and 77 prostate cancer patients. This assay provided reproducible and consistent results with low %CVs, and tolerance ranges were established for the assay. IgM levels measured using the Luminex assay were found to be highly correlated to the microarray results with R values of 0.93–0.95. This assay is a Laboratory Developed Test (LDT) and is suitable for evaluating thousands of serum samples in CLIA certified laboratories that have validated the assay. In addition, the study demonstrates that discoveries made using neoglycoprotein-based microarrays can be readily migrated to a clinical assay. PMID:28771597

Radiosensitivity of lymph node metastases versus initial subcutaneous tumors in nude mice

International Nuclear Information System (INIS)

Guichard, M.; Courdi, A.; Fertil, B.; Malaise, E.P.

1979-01-01

The in vivo and in vitro radiosensitivity of EMT6 tumor cells growing subcutaneously and metastasizing to the regional lymph nodes has been studied in congenitally athymic nude mice. The fraction of hypoxic cells was determined using an in vitro colony method to assay cell survival after irradiation of both air-breathing and nitrogen-asphyxiated animals. In air-breathing animals, lymph node metastases contained a significantly higher fraction of hypoxic cells than subcutaneous tumors of the same size (61 and 36% respectively). Survival curves did not differ under hypoxic conditions (nitrogen-asphyxiated animals). Likewise, survival curves of cells extracted from tumors at both sites and irradiated in vitro were identical

Recent experience in applying the cytogenetic dosimetry assay

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Khvostunov, I.K., E-mail: 726727@mrrc.obninsk.ru [Medical Radiological Research Centre, Koroliov Str. 4, Obninsk, Kaluga Region, 249036 (Russian Federation); Sevan' kaev, A.V. [Medical Radiological Research Centre, Koroliov Str. 4, Obninsk, Kaluga Region, 249036 (Russian Federation); Lloyd, D.C. [Health Protection Agency, Centre for Radiation, Chemical and Environmental Hazards, Chilton, Didcot, Oxfordshire (United Kingdom); Nugis, V.Yu. [Burnasyan Federal Medical Biophysical Center of the Federal Medical Biological Agency, Marshala Novikova Str., 23, Moscow (Russian Federation); Voisin, P. [Institute for Radiation Protection and Nuclear Safety, SRBE, B.P. 17, 92262 Fontenay-aux-Roses Cedex (France)

2011-09-15

This paper considers how well standard calibration curve for translocations constructed for lymphocyte cultures irradiated in vitro with gamma-rays from {sup 60}Co compares with the translocations yield in lymphocytes taken from people at a long post-exposure time. Data were used from radiation accident victims overexposed to doses ranging from 0.2 to 8.5 Gy and who were cytogenetically followed-up for various times upto 50 y. Their cultured lymphocytes had been scored both by the conventional dicentric method and by FISH for all translocations involving painted chromosomes (2, 3, 8); (2, 3, 5) or (2, 4, 12). The in vivo dose response relationship was derived by fitting translocation frequencies to the contemporary individual doses obtained independently and confirmed by different biological assays and physical dosimetry. A comparison with the conventional in vitro curve indicates reductions of translocation frequencies with increasing time which would prejudice retrospective dose assessment by FISH. This has led to the possibility to amend the in vitro dose response curve for translocations to make it more suitable for use in retrospective biodosimetry. This approach for retrospective biodosimetry therefore uses a dose response relationship based on truly persisting translocations.

Solid-phase immunoradiometric assay for C-reactive protein using magnetisable cellulose particles

International Nuclear Information System (INIS)

Beer, F.C. de; Pepys, M.B.

1982-01-01

An immunoradiometric assay (IRMA) for C-reactive protein (CRP) was developed using magnetisable cellulose particles as the solid-phase support for anti-CRP antibodies. 125 I-labelled immunopurified anti-CRP antibody was used to quantitate the amount of CRP taken up by the solid phase. Unbound label was easily and rapidly removed by decantation after sedimenting the particles on a magnet. The assay could detect 1 μg CRP/l and had a range of up to 10 mg/l with the portion of the standard curve between 10 μg/l and 2-3 mg/l being linear. Fifty samples per hour could be processed manually from serum to CRP result with an intra-assay CV of 5.2% and an inter-assay CV of 10.0%, based on 5 replicates of 5 samples with CRP levels between 2 mg/l and 180 mg/l run in 5 separate assays. Fifty clinical samples were assayed in parallel with a standard electroimmunoassay and yielded a linear correlation coefficient (r) of 0.975 and a slope of 0.98. With its single, brief incubation step including all reagents and its simple phase separation procedure the present method may be the assay of choice when precise measurement of CRP concentrations is required rapidly. (Auth.)

Effect of single-dose radiation on cell survival and growth hormone secretion by rat anterior pituitary cells

International Nuclear Information System (INIS)

Hochberg, Z.; Kuten, A.; Hertz, P.; Tatcher, M.; Kedar, A.; Benderly, A.

1983-01-01

Cranial irradiation has been shown to impair growth hormone secretion in children. In this study a cell culture of dispersed rat anterior pituitary cells was exposed to single doses of radiation in the range of 100 to 1500 rad. Survival curves were obtained for the different anterior pituitary cell lines, and growth hormone secretion was measured in the tissue culture medium. Both survival and growth hormone secretion curves showed an initial shoulder in the range of 0 to 300 rad, followed by a decline between 300 to 750 rad. It is concluded that growth hormone secreting acidophilic pituicytes are sensitive to radiation at single doses greater than 300 rad

Caffeine-enhanced survival of radiation-sensitive, repair-deficient Chinese hamster cells

International Nuclear Information System (INIS)

Utsumi, H.; Elkind, M.M.

1983-01-01

A clone of V79 Chinese hamster cells (V79-AL162/S-10) with unique properties has been isolated after a challenge of parental cells (V79-AL162) with 1 mM ouabain. Compared with parental cells, or with other clones isolated after the ouabain challenge, these cells form smaller colonies, are more sensitive to both x rays and fission-spectrum neutrons, and respond atypically to a postirradiation treatment with caffeine. Their enhanced response to x rays results mainly from a large reduction in the shoulder of their survival curve, probably because in late S phase, the most resistant phase in the cell cycle, the survival curve of these cells has a reduced shoulder width. Caffeine, and to a lesser extent theophylline, added to the colony-forming medium immediately after exposure appreciably increases the width of the shoulder of these sensitive cells, whereas caffeine has the opposite effect on the response of normal V79 cells. Thus the unique response of the V79-AL162/S-10 cells to a radiation posttreatment with caffeine (increased survival) results from a net increase in their ability to repair damage that is otherwise lethal; caffeine treatment ordinarly prevents normal V79 cells from repairing damage that is only potentially lethal

Dose-response curves from incomplete data

International Nuclear Information System (INIS)

Groer, P.G.

1978-01-01

Frequently many different responses occur in populations (animal or human) exposed to ionizing radiation. To obtain a dose-response curve, the exposed population is first divided into sub-groups whose members received the same radiation dose. To estimate the response, the fraction of subjects in each sub-group that showed the particular response of interest is determined. These fractions are plotted against dose to give the dose-response curve. This procedure of plotting the fractions versus the radiation dose is not the correct way to estimate the time distribution for a particular response at the different dose levels. Other observed responses competed for the individuals in the exposed population and therefore prevented manifestation of the complete information on the response-time distribution for one specific response. Such data are called incomplete in the statistical literature. A procedure is described which uses the by now classical Kaplan-Meier estimator, to establish dose-response curves from incomplete data under the assumption that the different observed responses are statistically independent. It is demonstrated that there is insufficient information in the observed survival functions to estimate the time distribution for one particular response if the assumption of independence is dropped. In addition, it is not possible to determine from the data (i.e. type of response and when it occurred) whether or not the different response-time distributions are independent. However, it is possible to give sharp bounds between which the response has to lie. This implies that for incomplete data, only a 'dose-response band' can be established if independence of the competing responses cannot be assumed. Examples are given using actual data to illustrate the estimation procedures

A high ratio of apoptosis to proliferation correlates with improved survival after radiotherapy for cervical adenocarcinoma

International Nuclear Information System (INIS)

Sheridan, Mary T.; Cooper, Rachel A.; West, Catharine M.L.

1999-01-01

Purpose: A retrospective study was made of the role of apoptosis in determining radiotherapy outcome in 39 adenocarcinoma of the cervix. A comparison was also made of the detection of apoptosis by morphology and the TdT dUtp nick end-labeling (TUNEL) assay. Methods and Materials: The level of apoptosis was assessed in paraffin-embedded sections by cell morphology, the TUNEL assay, and a combination of the two. A total of 2,000 cells were counted per section, to obtain apoptotic (AI) and mitotic (MI) indices. Results: Patients with a high AI had a higher survival rate than those with a low AI, however, the difference was not significant. Using a ratio of apoptosis to proliferation indices, patients with an AI:MI > median had significantly better survival than those with AI:MI < median. This was true where the AI was quantified by morphology alone (p = 0.030) or in combination with the TUNEL assay (p = 0.008). Where the AI was quantified by a combination of morphology and TUNEL, the 5-year survival rates for women with AI:MI greater or less than the median were 81% and 25%, respectively. Conclusion: A high ratio of AI:MI in adenocarcinoma of the cervix indicates a good prognosis. A combination of the TUNEL assay and morphology provided the best discrimination between outcome groups

Factors affecting a cyanogen bromide-based assay of thiamin.

Science.gov (United States)

Wyatt, D T; Lee, M; Hillman, R E

1989-11-01

We analyzed extensively a modified thiochrome method for thiamin analysis. Acid phosphatase (EC 3.1.3.2) from potato was superior to either alpha-amylase or acid phosphatase from wheat germ as a dephosphorylating agent. Timing of cyanogen bromide exposure was important, but the assay had good precision and accuracy. The standard curve was linear from 10 to 3000 nmol/L. The within-run and between-run coefficients of variation for total thiamin in whole blood were 3.6% and 7.4%, respectively. Analytical recoveries for low, intermediate, and high additions of thiamin to whole blood were 93-109%. Sample yield was increased by 41% (+/- 29% SD) with pre-assay freezing. Samples were stable for two days at room temperature, for seven days when refrigerated, and for two years when frozen. Previously unreported interference was seen with penicillin derivatives, and with several commonly used diuretic and antiepileptic medications. This assay may be suitable for population screening; 200 samples could be analyzed weekly at a cost of +0.20 per sample.

A Lateral Flow Protein Microarray for Rapid and Sensitive Antibody Assays

Directory of Open Access Journals (Sweden)

Helene Andersson-Svahn

2011-11-01

Full Text Available Protein microarrays are useful tools for highly multiplexed determination of presence or levels of clinically relevant biomarkers in human tissues and biofluids. However, such tools have thus far been restricted to laboratory environments. Here, we present a novel 384-plexed easy to use lateral flow protein microarray device capable of sensitive (< 30 ng/mL determination of antigen-specific antibodies in ten minutes of total assay time. Results were developed with gold nanobeads and could be recorded by a cell-phone camera or table top scanner. Excellent accuracy with an area under curve (AUC of 98% was achieved in comparison with an established glass microarray assay for 26 antigen-specific antibodies. We propose that the presented framework could find use in convenient and cost-efficient quality control of antibody production, as well as in providing a platform for multiplexed affinity-based assays in low-resource or mobile settings.

Postoperative serum CEA level as predictive factor for survival in patients with colorectal cancer

International Nuclear Information System (INIS)

Lemberger, J.J.; Bogar, M.L.; Takacs Kucsera, M.F.; Csernetics, I.F.

2002-01-01

Aim: It is known that routine follow-up of patients with resected colorectal cancer includes serial CEA determinations. In this retrospective study we have investigated relationship between CEA level and survival and whether achieved results enable differentiation of tumors with slow and rapid growth. Material and Methods: Mainly between 1995 and 1999 periodic CEA determination by IRMA were performed in 269 patients after curative resection of colorectal carcinoma. Number of CEA determination/patient were 2-16(median 6). Survival ranged 4,5 and>249,7 months. Based on CEA results patients were divided in group with normal (<10ng/ml) and elevated (=10ng/ml) values regardless of postoperative treatment. Survival curves were computed by Kaplan-Meier method and difference was evaluated by logrank test and difference between proportions. Results:Normal end elevated CEA was found in 193 and 76 patients, respectively. The difference of survival curves between patients with normal and elevated CEA are highly significant (p<0,0001). However, only 10 months after tumor resection is the difference between survived proportions significant suggesting already presence of CEA produced micrometastases contributing to progression of neoplastic process. The mean survival time at normal and elevated CEA values are 142,54±17,86(median 128,60±24,04) and 34,15±4,28 (median 25,20±1,97) months, respectively. No significant difference of survival was found regarding tumor localization. Conclusion:The results show that with regard to CEA level it is possible to divide colorectal tumors on marker negative and positive. Marker negative are with slower growth and relatively good prognosis. Marker positive are associated with elevated CEA level and with considerable shorter survival. Postoperative CEA level is valuable parameter in prediction of patient's outcome

Modification of UV-induced mutation frequency and cell survival of Escherichia coli B/r WP2 trpE65 by treatment before irradiation

International Nuclear Information System (INIS)

Doudney, C.O.; Rinaldi, C.N.

1984-01-01

The UV radiation survival curve of exponentially growing cultures of Escherichia coli B/r WP2 trpE65 was modified by pretreatment for short incubation periods (up to 20 min) with chloramphenicol such that an extended exponential section of intermediate slope appeared between the shoulder and the final exponential slope. Surges of mutation to tryptophan independence occurred with each increase in slope of the survival curve. These surges were separated by extended sections of little mutation. Nalidixic acid prevented both the changes in survival and mutation. Mutation curves obtained with overnight cultures had three extended sections of little mutation alternating with section of high mutation. Reincubation for 60 min in fresh medium reduced or eliminated the low-response sections. These reappeared after 80 to 90 min, when DNA had doubled in the culture and before the initial synchronous cell divisions had occurred. Nalidixic acid prevented this reappearance

Suitability of a Saccharomyces cerevisiae-based assay to assess the toxicity of pyrimethanil sprayed soils via surface runoff: comparison with standard aquatic and soil toxicity assays.

Science.gov (United States)

Gil, Fátima N; Moreira-Santos, Matilde; Chelinho, Sónia; Pereira, Carla; Feliciano, Joana R; Leitão, Jorge H; Sousa, José P; Ribeiro, Rui; Viegas, Cristina A

2015-02-01

The present study is aimed at evaluating whether a gene expression assay with the microbial eukaryotic model Saccharomyces cerevisiae could be used as a suitable warning tool for the rapid preliminary screening of potential toxic effects on organisms due to scenarios of soil and water contamination with pyrimethanil. The assay consisted of measuring changes in the expression of the selected pyrimethanil-responsive genes ARG3 and ARG5,6 in a standardized yeast population. Evaluation was held by assessing the toxicity of surface runoff, a major route of pesticide exposure in aquatic systems due to non-point-source pollution, which was simulated with a pyrimethanil formulation at a semifield scale mimicking worst-case scenarios of soil contamination (e.g. accident or improper disposal). Yeast cells 2-h exposure to the runoff samples led to a significant 2-fold increase in the expression of both indicator genes. These results were compared with those from assays with organisms relevant for the aquatic and soil compartments, namely the nematode Caenorhabditis elegans (reproduction), the freshwater cladoceran Daphnia magna (survival and reproduction), the benthic midge Chironomus riparius (growth), and the soil invertebrates Folsomia candida and Enchytraeus crypticus (survival and reproduction). Under the experimental conditions used to simulate accidental discharges into soil, runoff waters were highly toxic to the standard test organisms, except for C. elegans. Overall, results point out the usefulness of the yeast assay to provide a rapid preview of the toxicity level in preliminary screenings of environmental samples in situations of inadvertent high pesticide contamination. Advantages and limitations of this novel method are discussed. Copyright © 2014 Elsevier B.V. All rights reserved.

Dose response curve of induction of MN in lymphocytes for energies Cs-137; Curva dosis respuesta de induccion de micronucleos en linfocitos para las energias Cs-137

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Serna Berna, A.; Alcaraz, M.; Acevedo, C.; Vicente, V.; Fuente, I. de la; Canteras, M.

2006-07-01

The determination of the dose-response curve is a crucial step to use the Micronucleus assay in Lymphocytes as a biological dosimeters. The most widely used fitting function is the linear-quadratic function. The coefficients are fitted by calibration data provided by irradiations of blood from healthy donors. In our case we performed the calibration curve corresponding to gamma radiation from Cesium-137 (660 keV). Doses ranged from 0 to 16 Gy. The fitting procedure used was the iteratively re weighted least square algorithm implemented in a Matlab routine. The results of the analysis of our data show that the dose-effect curve does not follow a linear-quadratic curve at high radiation doses, diminishing the quadratic parameters as dose increases. This can be interpreted as a micronucleus saturation effect beyond a certain dose level. We conclude that the MN assay with lymphocytes can be well characterized as a biological dosimeters up to a maximum dose of 4.5 Gy. (Author)

Transient, heat-induced thermal resistance in the small intestine of mouse

International Nuclear Information System (INIS)

Hume, S.P.; Marigold, J.C.L.

1980-01-01

Heat-induced thermal resistance has been investigated in mouse jejunum by assaying crypt survival 24 h after treatment. Hyperthermia was achieved by immersing an exteriorized loop of intestine in a bath of Krebs-Ringer solution. Two approaches have been used. In the first, thermal survival curves were obtained following single hyperthermal treatments at temperatures in the range 42 to 44 0 C. Transient thermal resistance, inducted by a plateau in the crypt survival curve, developed during heating at temperatures around 42.5 0 C after 60 to 80 min. In the second series of experiments, a priming heat treatment (40.0, 41.0, 41.5, or 42.0 0 C for 60 min) was followed at varying intervals by a test treatment at 43.0 0 C. A transient resistance to the second treatment was induced, the extent and time of development being dependent upon the priming treatment. Crypt survival curves for thermally resistant intestine showed an increase in thermal D 0 and a decrease in n compared with curves from previously unheated intestine

Assaying environmental nickel toxicity using model nematodes

Science.gov (United States)

Rudel, David; Douglas, Chandler; Huffnagle, Ian; Besser, John M.; Ingersoll, Christopher G.

2013-01-01

Although nickel exposure results in allergic reactions, respiratory conditions, and cancer in humans and rodents, the ramifications of excess nickel in the environment for animal and human health remain largely undescribed. Nickel and other cationic metals travel through waterways and bind to soils and sediments. To evaluate the potential toxic effects of nickel at environmental contaminant levels (8.9-7,600 µg Ni/g dry weight of sediment and 50-800 µg NiCl2/L of water), we conducted assays using two cosmopolitan nematodes, Caenorhabditis elegans and Pristionchus pacificus. We assayed the effects of both sediment-bound and aqueous nickel upon animal growth, developmental survival, lifespan, and fecundity. Uncontaminated sediments were collected from sites in the Midwestern United States and spiked with a range of nickel concentrations. We found that nickel-spiked sediment substantially impairs both survival from larval to adult stages and adult longevity in a concentration-dependent manner. Further, while aqueous nickel showed no adverse effects on either survivorship or longevity, we observed a significant decrease in fecundity, indicating that aqueous nickel could have a negative impact on nematode physiology. Intriguingly, C. elegansand P. pacificus exhibit similar, but not identical, responses to nickel exposure. Moreover, P. pacificus could be tested successfully in sediments inhospitable to C. elegans. Our results add to a growing body of literature documenting the impact of nickel on animal physiology, and suggest that environmental toxicological studies could gain an advantage by widening their repertoire of nematode species.

An enzyme-linked immunoabsorbent assay for estimating red cell survival of transfused red cells-validation using CR-51 labeling

International Nuclear Information System (INIS)

Drew, H.; Kickler, T.; Smith, B.; LaFrance, N.

1984-01-01

The survival time of transfused red cells antigenically distinct from the recipient's red cells was determined using an indirect enzyme linked antiglobulin test. These results were then compared to those determined by Cr-51 labeling. Three patients with hypoproliferative anemias and one patient (2 studies) with traumatic hemolytic anemia caused by a prosthetic heart valve were studied. Survival times were performed by transfusing a 5cc aliquot of Cr-51 labeled cells along with the remaining unit. One hour post transfusion, a blood sample was drawn and used as the 100% value. Subsequent samples drawn over a 2-3 week period were then compared to the initial sample to determine percent survival for both methods. The ELISA method for measuring red cell survival in antigenically distinct cells is in close agreement with the Cr-51 method. Although CR-51 labeling is the accepted method for red cell survival determination the ELISA method can be used when radioisotopes are unavailable or contraindicated or when the decision to estimate red cell survival is made after transfusion

The effect of the freezing curve type on bull spermatozoa motility after thawing

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Martina Doležalová

2015-01-01

Full Text Available The objective of this work was to determine the effect of selected freezing curves on spermatozoa survivability after thawing, defined by its motility. The ejaculates of nine selected sires of the same age, breed, and frequency of collecting, bred under the same breeding conditions including handling, stabling, feeding system and feeding ratio composition, were repeatedly collected and evaluated. Sperm samples of each sire were diluted using only one extender and divided into four parts. Selected four freezing curves – the standard, commercially recommended three-phase curve; a two-phase curve; a slow three-phase curve; and a fast three-phase curve, differing in the course of temperature vs time, were applied. The percentage rate of progressive motile spermatozoa above head was determined immediately after thawing, and after 30, 60, 90, and 120 min of the thermodynamic test (TDT. Moreover, average spermatozoa motility (AMOT and spermatozoa motility decrease (MODE throughout the entire TDT were evaluated. Insemination doses frozen using the simpler two-phase curve demonstrated the highest motility values (+2.97% to +10.37%; P < 0.05–0.01 immediately after thawing and during the entire TDT. Concurrently, the highest AMOT (+4.37% to +8.82%; P < 0.01 was determined. The highest spermatozoa motility values were detected after thawing doses frozen by the two-phase freezing curve in eight out of nine sires. Simultaneously, a significant effect of sire individuality was clearly confirmed. Inter-sire differences of spermatozoa motility during TDT as well as AMOT and MODE were significant (P < 0.01. The findings describing both factors of interaction indicate the necessity of individual cryopreservation of the ejaculate to increase its fertilization capability after thawing.

Advanced Online Survival Analysis Tool for Predictive Modelling in Clinical Data Science.

Science.gov (United States)

Montes-Torres, Julio; Subirats, José Luis; Ribelles, Nuria; Urda, Daniel; Franco, Leonardo; Alba, Emilio; Jerez, José Manuel

2016-01-01

One of the prevailing applications of machine learning is the use of predictive modelling in clinical survival analysis. In this work, we present our view of the current situation of computer tools for survival analysis, stressing the need of transferring the latest results in the field of machine learning to biomedical researchers. We propose a web based software for survival analysis called OSA (Online Survival Analysis), which has been developed as an open access and user friendly option to obtain discrete time, predictive survival models at individual level using machine learning techniques, and to perform standard survival analysis. OSA employs an Artificial Neural Network (ANN) based method to produce the predictive survival models. Additionally, the software can easily generate survival and hazard curves with multiple options to personalise the plots, obtain contingency tables from the uploaded data to perform different tests, and fit a Cox regression model from a number of predictor variables. In the Materials and Methods section, we depict the general architecture of the application and introduce the mathematical background of each of the implemented methods. The study concludes with examples of use showing the results obtained with public datasets.

Hidden stressors in the clonogenic assay used in radiobiology experiments

International Nuclear Information System (INIS)

Potter, M.D.E.; Suchowerska, N.; Rizvi, S.; McKenzie, D.R.

2011-01-01

Full text: While clonogenic assays are extensively used in radiobiology, there is no widely accepted procedure for choosing the composition of the cell culture media. Cell line suppliers recommend a specific culture medium for each cell line, however a researcher will frequently customize this aspect of the protocol by supplementing the recommended support medium with additives. For example, many researchers add antibiotics, in order to avoid contamination of cells and the consequent loss of data, with little discussion of the influence of the antibiotics on the clonogenic survival of the cells. It is assumed that the effect of any variables in the growth medium on cell survival is taken into consideration by comparing the survival fraction relative to that of controls grown under the same conditions. In the search for better cancer treatment, the effect of various stressors on clonogenic cell survival is under investigation. This study seeks to identify and test potential stressors commonly introduced into the cell culture medium, which may confound the response to radiation. (author)

Stability study for magnetic reagent assaying Hb and HbA1c

International Nuclear Information System (INIS)

Hsieh, Wen-Pin; Chieh, J.J.; Yang, C.C.; Yang, S.Y.; Chen, Po-Yu; Huang, Yu-Hao; Hong, Y.W.; Horng, H.E.

2013-01-01

Reagents for magnetically labeled immunoassay on human Hb and human HbA1c have been synthesized. The reagents consist of Fe 3 O 4 magnetic particles biofunctionalized with antibodies against Hb and HbA1c. It has been demonstrated that the reagents can be applied to quantitatively detect Hb and HbA1c by using immunomagnetic reduction assay. In addition to characterizing the assay properties, such as the standard curve and the low-detection limit, the stability of reagents is investigated. To do this, the temporal dependence of particle sizes and the bio-activity of reagents are monitored. The results show that the reagents are highly stable when stored at 2–8 °C. This means that the reagents synthesized in this work are promising for practical applications. - Highlights: ► The properties of assaying Hb and HbA1c using immunomagnetic reduction are studied. ► The magnetic nanoparticles with antibodies are highly stable in solutions. ► No significant mutual interference between Hb and HbA1c in assays is observed. ► High-sensitivity assays on Hb and HbA1c using immunomagnetic reduction are achieved.

Reference cells and ploidy in the comet assay

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Gunnar eBrunborg

2015-02-01

Full Text Available In the comet assay, single cells are analyzed with respect to their level of DNA damage. Discrimination of the individual cell or cell type based on DNA content, with concomitant scoring of the DNA damage, is useful since this may allow analysis of mixtures of cells. Different cells can then be characterized based on their ploidy, cell cycle stage, or genome size. We here describe two applications of such a cell type-specific comet assay: (i Testicular cell suspensions, analyzed on the basis of their ploidy during spermatogenesis; and (ii reference cells in the form of fish erythrocytes which can be included as internal standards to correct for inter-assay variations. With standard fluorochromes used in the comet assay, the total staining signal from each cell – whether damaged or undamaged – was found to be associated with the cell’s DNA content. Analysis of the fluorescence intensity of single cells is straightforward since these data are available in scoring systems based on image analysis. The analysis of testicular cell suspensions provides information on cell type specific composition, susceptibility to genotoxicants, and DNA repair. Internal reference cells, either untreated or carrying defined numbers of lesions induced by ionizing radiation, are useful for investigation of experimental factors that can cause variation in comet assay results, and for routine inclusion in experiments to facilitate standardization of methods and comparison of comet assay data obtained in different experiments or in different laboratories. They can also be used - in combination with a reference curve - to quantify the DNA lesions induced by a certain treatment. Fish cells of a range of genome sizes, both greater and smaller than human, are suitable for this purpose and they are inexpensive.

Survival pathological prognosis factors in breast cancer

International Nuclear Information System (INIS)

Gonzalez-Longoria Boada, Lourdes B.

2012-01-01

A descriptive and longitudinal study of 273 women with breast cancer belonging to Granma province was carried out from 2003 to 2004, in order to analyze the survival of this female population, reason why the method of Kaplan Meier was used for the calculation of the mentioned variable and the Log Rank test was used for the comparison of curves. Patients with higher survival at 5 years were those who had tumors of 2 cm or less (87.5%), histological grade I (90.3%), nuclear grade I (88.3%), as well as the absence of vascular, lymphatic or lymph node invasion (with 80.6; 74.9 and 6.1% respectively). Also, tumor size, histological and nuclear grade, nodal status, as well as lymphatic and vascular invasion constituted prognosis factors, which favored the individualization of therapeutic behaviors

The prognostic value of the suPARnosticTM ELISA assay in HIV-1 infected individuals is not affected by uPAR promoter polymorphisms

DEFF Research Database (Denmark)

Schneider, Uffe Vest; Nielsen, Rikke Lyngaa; Pedersen, Court

2007-01-01

BACKGROUND: High blood levels of soluble urokinase Plasminogen Activator Receptor (suPAR) are associated with poor outcomes in human immunodeficiency-1 (HIV-1) infected individuals. Research on the clinical value of suPAR in HIV-1 infection led to the development of the suPARnosticTM assay...... for commercial use in 2006. The aim of this study was to: 1) Evaluate the prognostic value of the new suPARnosticTM assay and 2) Determine whether polymorphisms in the active promoter of uPAR influences survival and/or suPAR values in HIV-1 patients who are antiretroviral therapy (ART) naive. METHODS: DNA...... and an A to G transition at -465 comparative to the transcription start site. These promoter transitions did not influence neither the suPAR levels nor patient survival. CONCLUSION: Plasma suPAR levels, as measured by the suPARnosticTM assay, were strongly predictive of survival in ART-naive HIV-1 infected...

New fluorimetric assay of horseradish peroxidase using sesamol as substrate and its application to EIA.

Science.gov (United States)

Arakawa, Hidetoshi; Nakabayashi, Shigeo; Ohno, Ken-Ichi; Maeda, Masako

2012-04-01

Horseradish peroxidase (HRP) is generally used as a label enzyme in enzyme immunoassay (EIA). The procedure used for HRP detection in EIA is critical for sensitivity and precision. This paper describes a novel fluorimetric assay for horseradish peroxidase (HRP) using sesamol as substrate. The principle of the assay is as follow: sesamol (3,4-methylenedioxy phenol) is reacted enzymatically in the presence of hydrogen peroxide to produce dimeric sesamol. The dimer is fluorescent and can be detected sensitively at ex. 347 nm, em. 427 nm. The measurable range of HRP was 1.0×10 -18 to 1.0×10 -15  mol/assay, with a detection limit of 1.0×10 -18  mol/assay. The coefficient of variation (CV, n =8) was examined at each point on the standard curve, with a mean CV percentage of 3.8%. This assay system was applied to thyroid stimulating hormone (TSH) EIA using HRP as the label enzyme.

Survival with breast cancer: the importance of estrogen receptor quantity.

Science.gov (United States)

Shek, L L; Godolphin, W

1989-02-01

The survival of 1184 British Columbian women whose primary breast cancers were diagnosed and assayed for estrogen receptor (ER) between 1975 and 1981 was studied. Median follow-up was 60 months. ER concentrations yielded greater prognostic information than simple positive and negative categories. When ER data were divided into four strata: less than or equal to 1, 2-9, 10-159 and greater than or equal to 160 fmol/mg cytosol protein, the association of higher ER with prolonged survival was highly significant (P less than 0.0001) and independent of TNM stage, nodal status and menopausal status. ER less than or equal to 1 and ER = 2-9 groups were distinct with respect to overall disease-specific survival. Patient age did not predict survival when controlled for ER. Prolonged recurrence-free survival was associated with higher ER (P = 0.0001) for at least 5 years after diagnosis. This significant trend persisted after adjustments for nodal status, TNM stage, menopausal status and the type of systemic adjuvant therapy.

Survival of pathogenic and lactobacilli species of fermented olives during simulated human digestion.

Science.gov (United States)

Arroyo-López, Francisco N; Blanquet-Diot, Stéphanie; Denis, Sylvain; Thévenot, Jonathan; Chalancon, Sandrine; Alric, Monique; Rodríguez-Gómez, Francisco; Romero-Gil, Verónica; Jiménez-Díaz, Rufino; Garrido-Fernández, Antonio

2014-01-01

The present survey uses a dynamic gastric and small intestinal model to assess the survival of one pathogenic (Escherichia coli O157:H7 EDL 933) and three lactobacilli bacteria with probiotic potential (Lactobacillus rhamnosus GG, L. pentosus TOMC-LAB2, and L. pentosus TOMC-LAB4) during their passage through the human gastrointestinal tract using fermented olives as the food matrix. The data showed that the survival of the E. coli strain in the stomach and duodenum was very low, while its transit through the distal parts (jejunum and ileum) resulted in an increase in the pathogen population. The production of Shiga toxins by this enterohemorrhagic microorganism in the ileal effluents of the in vitro system was too low to be detected by ELISA assays. On the contrary, the three lactobacilli species assayed showed a considerable resistance to the gastric digestion, but not to the intestinal one, which affected their survival, and was especially evident in the case of both L. pentosus strains. In spite of this, high population levels for all assayed microorganisms were recovered at the end of the gastrointestinal passage. The results obtained in the present study show the potential use of table olives as a vehicle of beneficial microorganisms to the human body, as well as the need for good hygienic practices on the part of olive manufacturers in order to avoid the possibility of contamination by food-borne pathogens.

Survival of pathogenic and lactobacilli species of fermented olives during simulated human digestion

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Francisco Noé eArroyo López

2014-10-01

Full Text Available The present survey uses a dynamic gastric and small intestinal model to assess the survival of one pathogenic (Escherichia coli O157:H7 EDL 933 and three lactobacilli bacteria with probiotic potential (Lactobacillus rhamnosus GG, Lactobacillus pentosus TOMC-LAB2 and Lactobacillus pentosus TOMC-LAB4 during their passage through the human gastrointestinal tract using fermented olives as the food matrix. The data showed that the survival of the E. coli strain in the stomach and duodenum was very low, while its transit through the distal parts (jejunum and ileum resulted in an increase in the pathogen population. The production of Shiga toxins by this enterohemorrhagic microorganism in the ileal effluents of the in vitro system was too low to be detected by ELISA assays. On the contrary, the three lactobacilli species assayed showed a considerable resistance to the gastric digestion, but not to the intestinal one, which affected their survival, and was especially evident in the case of both L. pentosus strains. In spite of this, high population levels for all assayed microorganisms were recovered at the end of the gastrointestinal passage. The results obtained in the present study show the potential use of table olives as a vehicle of beneficial microorganisms to the human body, as well as the need for good hygienic practices on the part of olive manufacturers in order to avoid the possibility of contamination by food-borne pathogens.

In vivo studies of the long-term 51Cr red cell survival of serologically incompatible red cell units

International Nuclear Information System (INIS)

Baldwin, M.L.; Ness, P.M.; Barrasso, C.; Kickler, T.S.; Drew, H.; Tsan, M.F.; Shirey, R.S.

1985-01-01

The long-term survival of serologically incompatible red cell units was measured in five patients with antibodies to high-frequency antigens. Initially, the survival of 1 ml of 51 Cr-labeled incompatible red cells was measured over 1 hour. After demonstrating that the 1-hour survival times were successful (greater than 70%), each patient then received 5 ml of the same 51 Cr-labeled red cells followed by the transfusion of the remainder of the red cell unit. The long-term T 1/2Cr survival for each case was patient 1 (anti-McCa), 15 days; patient 2 (anti-JMH), 12 days; patient 3 (anti-Kna), 31 days; patient 4 (anti-McCa), 12 days; and patient 5 (anti-Hya), 14 days. Each antibody tested in an in vitro homologous macrophage assay showed less than 5 percent phagocytosis. Anti-JMH was the only antibody to react with IgG subclass antisera and was determined to be IgG4. The macrophage assay, IgG subclass testing, and short-term (1 hour, 1 ml) 51 Cr survival studies all indicated that the short-term survival was good. However, only the measurement of long-term survival with transfused units of serologically incompatible red cells was able to determine the actual survival, and clinical significance of the alloantibodies. Determining the actual long-term survival by the method described here can be of importance for patients requiring chronic red cell transfusion

Improved survival in HIV treatment programs in Asia

Science.gov (United States)

De La Mata, Nicole L; Kumarasamy, Nagalingeswaran; Khol, Vohith; Ng, Oon Tek; Van Nguyen, Kinh; Merati, Tuti Parwati; Pham, Thuy Thanh; Lee, Man Po; Durier, Nicolas; Law, Matthew

2016-01-01

Background Antiretroviral treatment (ART) for HIV-positive patients has expanded rapidly in Asia over the last ten years. Our study aimed to describe the time trends and risk factors for overall survival in patients receiving first-line ART in Asia. Methods We included HIV-positive adult patients who initiated ART between 2003–2013 (n=16 546), from seven sites across six Asia-Pacific countries. Patient follow-up was to May 2014. We compared survival for each country and overall by time period of ART initiation using Kaplan-Meier curves. Factors associated with mortality were assessed using Cox regression, stratified by site. We also summarized first-line ART regimens, CD4 count at ART initiation, and CD4 and HIV viral load testing frequencies. Results There were 880 deaths observed over 54 532 person-years of follow-up, a crude rate of 1.61 (1.51, 1.72) per 100 person-years. Survival significantly improved in more recent years of ART initiation. The survival probabilities at 4 years follow-up for those initiating ART in 2003–05 was 92.1%, 2006–09 was 94.3% and 2010–2013 was 94.5% (pAsia have improved survival in more recent years of ART initiation. This is likely a consequence of improvements in treatment and, patient management and monitoring over time. PMID:26961354

Stenting for curved lesions using a novel curved balloon: Preliminary experimental study.

Science.gov (United States)

Tomita, Hideshi; Higaki, Takashi; Kobayashi, Toshiki; Fujii, Takanari; Fujimoto, Kazuto

2015-08-01

Stenting may be a compelling approach to dilating curved lesions in congenital heart diseases. However, balloon-expandable stents, which are commonly used for congenital heart diseases, are usually deployed in a straight orientation. In this study, we evaluated the effect of stenting with a novel curved balloon considered to provide better conformability to the curved-angled lesion. In vitro experiments: A Palmaz Genesis(®) stent (Johnson & Johnson, Cordis Co, Bridgewater, NJ, USA) mounted on the Goku(®) curve (Tokai Medical Co. Nagoya, Japan) was dilated in vitro to observe directly the behavior of the stent and balloon assembly during expansion. Animal experiment: A short Express(®) Vascular SD (Boston Scientific Co, Marlborough, MA, USA) stent and a long Express(®) Vascular LD stent (Boston Scientific) mounted on the curved balloon were deployed in the curved vessel of a pig to observe the effect of stenting in vivo. In vitro experiments: Although the stent was dilated in a curved fashion, stent and balloon assembly also rotated conjointly during expansion of its curved portion. In the primary stenting of the short stent, the stent was dilated with rotation of the curved portion. The excised stent conformed to the curved vessel. As the long stent could not be negotiated across the mid-portion with the balloon in expansion when it started curving, the mid-portion of the stent failed to expand fully. Furthermore, the balloon, which became entangled with the stent strut, could not be retrieved even after complete deflation. This novel curved balloon catheter might be used for implantation of the short stent in a curved lesion; however, it should not be used for primary stenting of the long stent. Post-dilation to conform the stent to the angled vessel would be safer than primary stenting irrespective of stent length. Copyright © 2014 Japanese College of Cardiology. Published by Elsevier Ltd. All rights reserved.

Multiplex assay (Mikrogen recomBead) for detection of serum IgG and IgM antibodies to 13 recombinant antigens of Borrelia burgdorferi sensu lato in patients with neuroborreliosis

DEFF Research Database (Denmark)

Dessau, Ram Benny; Møller, Jens K.; Kolmos, Birte

2015-01-01

A multiplex-bead-based assay for the detection of serum antibodies to Borrelia burgdorferi sensu lato was evaluated. The assay contained 13 different antigens in both the IgG and the IgM assay; thus, a total of 26 measurement results were available from each sample. A total of 49 Danish patients......, the construction of a diagnostic score, evaluation of the scoring method using an independent dataset and an assessment of the analytical quality of the multiplex assay. The VlsE IgG had the highest diagnostic value with an AUC (area under the curve) of 96% on the receiver operating characteristic curve. The Osp......C IgM had AUCs just above 80%. All the other antigens had both low quantitative reactivity and lower contrast in the patients with LNB compared to controls. The diagnostic value of the assay may be improved by using a logistic model giving a sensitivity of 90 and 79% for the specificities at 92 and 98...

The assay of glucocerebrosidase activity using the natural substrate

International Nuclear Information System (INIS)

Strasberg, P.M.; Lowden, J.A.

1982-01-01

The authors have examined eight published methods for the assay of glucocerebrosidase using the natural substrate glucocerebroside and tabulated the variable components and conditions while comparing these methods to their own. In each case assays were performed using a 8000 fold, partially purified human placental enzyme, having a pH optimum of 5.4-5.6 and a Ksub(m) of approximately 0.60 mmol per liter. Results were obtained by following the release of radioactive ceramide or of unlabelled glucose. In many cases published results had been based on a one- or two-hour incubation time. Apparent specific activities varied over a 70-fold difference between the various procedures. When the authors measured activities from the linear (15-30 min) portion of rate curves the values increased by 1.4 to 3 times but still ranged from 6x10 3 -180x10 3 nmol. mg -1 protein h -1 . They obtained maximum velocity using 1.2 mmol glucocerebroside, 0.5% (w/v) crude taurocholate and 2 μg enzyme protein/ml. Specific activities reported from different laboratories are not directly comparable. Conditions for assay should be optimized for the enzyme preparation to be studied. (Auth.)

Single-dilution enzyme-linked immunosorbent assay for quantification of antigen-specific salmonid antibody

Science.gov (United States)

Alcorn, S.W.; Pascho, R.J.

2000-01-01

An enzyme-linked immunosorbent assay (ELISA) was developed on the basis of testing a single dilution of serum to quantify the level of antibody to the p57 protein of Renibaclerium salmoninarum in sockeye salmon (Oncorhynchus nerka). The levels of antibody were interpolated from a standard curve constructed by relating the optical densities (OD) produced by several dilutions of a high-titer rainbow trout (O. mykiss) antiserum to the p57 protein. The ELISA OD values produced by as many as 36 test sera on each microplate were compared with the standard curve to calculate the antigen-specific antibody activity. Repeated measurements of 36 samples on 3 microplates on each of 6 assay dates indicated that the mean intraassay coefficient of variation (CV) was 6.68% (range, 0-23%) and the mean interassay CV was 8.29% (range, 4-16%). The antibody levels determined for the serum sample from 24 sockeye salmon vaccinated with a recombinant p57 protein generally were correlated with the levels determined by endpoint titration (r2 = 0.936) and with results from another ELISA that was based on extrapolation of antibody levels from a standard curve (r2 = 0.956). The single-dilution antibody ELISA described here increases the number of samples that can be tested on each microplate compared with immunoassays based on analysis of several dilutions of each test serum. It includes controls for interassay standardization and can be used to test fish weighing <3 g.

Curve Boxplot: Generalization of Boxplot for Ensembles of Curves.

Science.gov (United States)

Mirzargar, Mahsa; Whitaker, Ross T; Kirby, Robert M

2014-12-01

In simulation science, computational scientists often study the behavior of their simulations by repeated solutions with variations in parameters and/or boundary values or initial conditions. Through such simulation ensembles, one can try to understand or quantify the variability or uncertainty in a solution as a function of the various inputs or model assumptions. In response to a growing interest in simulation ensembles, the visualization community has developed a suite of methods for allowing users to observe and understand the properties of these ensembles in an efficient and effective manner. An important aspect of visualizing simulations is the analysis of derived features, often represented as points, surfaces, or curves. In this paper, we present a novel, nonparametric method for summarizing ensembles of 2D and 3D curves. We propose an extension of a method from descriptive statistics, data depth, to curves. We also demonstrate a set of rendering and visualization strategies for showing rank statistics of an ensemble of curves, which is a generalization of traditional whisker plots or boxplots to multidimensional curves. Results are presented for applications in neuroimaging, hurricane forecasting and fluid dynamics.

JUMPING THE CURVE

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René Pellissier

2012-01-01

Full Text Available This paper explores the notion ofjump ing the curve,following from Handy 's S-curve onto a new curve with new rules policies and procedures. . It claims that the curve does not generally lie in wait but has to be invented by leadership. The focus of this paper is the identification (mathematically and inferentially ofthat point in time, known as the cusp in catastrophe theory, when it is time to change - pro-actively, pre-actively or reactively. These three scenarios are addressed separately and discussed in terms ofthe relevance ofeach.

Impact of periodontal maintenance on tooth survival in patients with removable partial dentures.

Science.gov (United States)

Tada, Sayaka; Allen, Patrick Finbarr; Ikebe, Kazunori; Matsuda, Ken-ichi; Maeda, Yoshinobu

2015-01-01

Removable partial dentures (RPDs) may have a negative impact on oral health and have the potential to cause further tooth loss, especially of abutment teeth. However, no evidence indicates the effective interval of regular periodontal maintenance after RPD provision. This practice-based cohort study aimed to examine the impact of regular periodontal maintenance visits on survival of RPD abutment teeth. One hundred and ninety-two patients had been previously provided with 304 new clasp-retained RPDs at Osaka University Dental Hospital, Japan. Using the Kaplan-Meier method and log-rank test, 1094 abutments were analysed to illustrate survival curves and to compare each curve. According to the frequency of periodontal maintenance, study samples were divided into three groups; every 3-6 months (3-6M) group, 1-year (1Y) group and no-maintenance (NM) group. Seven-year cumulative survival rates were 83.7% (3-6M), 75.5% (1Y) and 71.9% (NM) respectively. Survival of abutment teeth in the 3-6M group was significantly better than both 1Y (p = 0.005) and NM (p < 0.001) groups. These longitudinal clinical data indicates that periodontal maintenance at least once in 6 months had the most favourable outcome. Frequent periodontal maintenance after RPD provision could be effective in preventing further tooth loss. © 2014 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.

Dual Smarandache Curves of a Timelike Curve lying on Unit dual Lorentzian Sphere

OpenAIRE

Kahraman, Tanju; Hüseyin Ugurlu, Hasan

2016-01-01

In this paper, we give Darboux approximation for dual Smarandache curves of time like curve on unit dual Lorentzian sphere. Firstly, we define the four types of dual Smarandache curves of a timelike curve lying on dual Lorentzian sphere.

Assaying environmental nickel toxicity using model nematodes.

Directory of Open Access Journals (Sweden)

David Rudel

Full Text Available Although nickel exposure results in allergic reactions, respiratory conditions, and cancer in humans and rodents, the ramifications of excess nickel in the environment for animal and human health remain largely undescribed. Nickel and other cationic metals travel through waterways and bind to soils and sediments. To evaluate the potential toxic effects of nickel at environmental contaminant levels (8.9-7,600 µg Ni/g dry weight of sediment and 50-800 µg NiCl2/L of water, we conducted assays using two cosmopolitan nematodes, Caenorhabditis elegans and Pristionchus pacificus. We assayed the effects of both sediment-bound and aqueous nickel upon animal growth, developmental survival, lifespan, and fecundity. Uncontaminated sediments were collected from sites in the Midwestern United States and spiked with a range of nickel concentrations. We found that nickel-spiked sediment substantially impairs both survival from larval to adult stages and adult longevity in a concentration-dependent manner. Further, while aqueous nickel showed no adverse effects on either survivorship or longevity, we observed a significant decrease in fecundity, indicating that aqueous nickel could have a negative impact on nematode physiology. Intriguingly, C. elegans and P. pacificus exhibit similar, but not identical, responses to nickel exposure. Moreover, P. pacificus could be tested successfully in sediments inhospitable to C. elegans. Our results add to a growing body of literature documenting the impact of nickel on animal physiology, and suggest that environmental toxicological studies could gain an advantage by widening their repertoire of nematode species.

Survival of microorganisms in smectite clays: Implications for Martian exobiology

Science.gov (United States)

Moll, Deborah M.; Vestal, J. Robie

1992-08-01

Manned exploration of Mars may result in the contamination of that planet with terrestrial microbes, a situation requiring assessment of the survival potential of possible contaminating organisms. In this study, the survival of Bacillus subtilis, Azotobacter chroococcum, and the enteric bacteriophage MS2 was examined in clays representing terrestrial (Wyoming type montmorillonite) or Martian (Fe 3+-montmorillonite) soils exposed to terrestrial and Martian environmental conditions of temperature and atmospheric pressure and composition, but not to UV flux or oxidizing conditions. Survival of bacteria was determined by standard plate counts and biochemical and physiological measurements over 112 days. Extractable lipid phosphate was used to measure microbial biomass, and the rate of 14C-acetate incorporation into microbial lipids was used to determine physiological activity. MS2 survival was assayed by plaque counts. Both bacterial types survived terrestrial or Martian conditions in Wyoming montmorillonite better than Martian conditions in Fe 3+-montmorillonite. Decreased survival may have been caused by the lower pH of the Fe 3+-montmorillonite compared to Wyoming montmorillonite. MS2 survived simulated Mars conditions better than the terrestrial environment, likely due to stabilization of the virus caused by the cold and dry conditions of the simulated Martian environment. The survival of MS2 in the simulated Martian environment is the first published indication that viruses may be able to survive in Martian type soils. This work may have implications for planetary protection for future Mars missions.

Effect of total lymphoid irradiation on pancreatic islet xenograft survival in rats

International Nuclear Information System (INIS)

Nakajima, Y.; Lie, T.S.; Nakauo, H.; Nakagawa, K.; Segawa, M.

1984-01-01

Before transplantation of Syrian hamster pancreatic islet xenografts to diabetic rats the recipients received total lymphatic system irradiation and cyclosporin A treatment after transplantation for immunosuppression. The xenograft survival times were measured and the rat anti-hamster lymphocytotoxic titers were determined by 51 Cr release assay

Effect of total lymphoid irradiation on pancreatic islet xenograft survival in rats

Energy Technology Data Exchange (ETDEWEB)

Nakajima, Y; Lie, T S [Bonn Univ. (Germany, F.R.). Chirurgische Klinik und Poliklinik; Nakauo, H; Nakagawa, K; Segawa, M [Nara Women' s Univ. (Japan). Dept. of Physics

1984-01-01

Before transplantation of Syrian hamster pancreatic islet xenografts to diabetic rats the recipients received total lymphatic system irradiation and cyclosporin A treatment after transplantation for immunosuppression. The xenograft survival times were measured and the rat anti-hamster lymphocytotoxic titers were determined by /sup 51/Cr release assay.

ECM using Edwards curves

DEFF Research Database (Denmark)

Bernstein, Daniel J.; Birkner, Peter; Lange, Tanja

2013-01-01

-arithmetic level are as follows: (1) use Edwards curves instead of Montgomery curves; (2) use extended Edwards coordinates; (3) use signed-sliding-window addition-subtraction chains; (4) batch primes to increase the window size; (5) choose curves with small parameters and base points; (6) choose curves with large...

Stability study for magnetic reagent assaying Hb and HbA1c

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Hsieh, Wen-Pin [Actherm Inc., Hsinchu 200, Taiwan (China); Chieh, J.J.; Yang, C.C. [Institute of Electro-optical Science and Technology, National Taiwan Normal University, Taipei 116, Taiwan (China); Yang, S.Y. [Institute of Electro-optical Science and Technology, National Taiwan Normal University, Taipei 116, Taiwan (China); MagQu Co., Ltd., Sindian Dist., New Taipei City 231, Taiwan (China); Chen, Po-Yu; Huang, Yu-Hao [Actherm Inc., Hsinchu 200, Taiwan (China); Hong, Y.W. [Institute of Electro-optical Science and Technology, National Taiwan Normal University, Taipei 116, Taiwan (China); Horng, H.E., E-mail: phyfv001@ntnu.edu.tw [Institute of Electro-optical Science and Technology, National Taiwan Normal University, Taipei 116, Taiwan (China)

2013-01-15

Reagents for magnetically labeled immunoassay on human Hb and human HbA1c have been synthesized. The reagents consist of Fe{sub 3}O{sub 4} magnetic particles biofunctionalized with antibodies against Hb and HbA1c. It has been demonstrated that the reagents can be applied to quantitatively detect Hb and HbA1c by using immunomagnetic reduction assay. In addition to characterizing the assay properties, such as the standard curve and the low-detection limit, the stability of reagents is investigated. To do this, the temporal dependence of particle sizes and the bio-activity of reagents are monitored. The results show that the reagents are highly stable when stored at 2-8 Degree-Sign C. This means that the reagents synthesized in this work are promising for practical applications. - Highlights: Black-Right-Pointing-Pointer The properties of assaying Hb and HbA1c using immunomagnetic reduction are studied. Black-Right-Pointing-Pointer The magnetic nanoparticles with antibodies are highly stable in solutions. Black-Right-Pointing-Pointer No significant mutual interference between Hb and HbA1c in assays is observed. Black-Right-Pointing-Pointer High-sensitivity assays on Hb and HbA1c using immunomagnetic reduction are achieved.

Determination of luteinizing hormone in bovine blood by radioligand receptor assay and comparison with radioimmunological evaluation

International Nuclear Information System (INIS)

Schams, D.; Menzer, C.

1978-01-01

A sensitive and specific radioligand receptor assay (RRA) using rat testis homogenate as the receptor source is described for measurement of luteinizing hormone (LH) in bovine blood. Interfering and nonspecific substances in blood were removed by means of ion-exchange chromatography on CM-Sephadex C-50. Criteria of validation such as recovery of added LH to plasma or serum, reproducibility, and specificity gave good results. Inhibition curves obtained with bovine plasma and serum were parallel to those obtained with the bovine standard preparation. The range of the dose-response curve was between 0.5-20 ng of bovine LH. The pattern of LH concentrations in purified serum samples under different physiological conditions such as during the oestrous cycle and after administration of GnRH showed a very close correlattion whether measured by means of radioimmunoassay (RIA) or receptor assay. Values of RRA-LH were consistently higher than those of RIA-LH. Thus the lower the RIA-LH levels, the more pronounced were the discrepancies between results of both assay systems. The mean ratio of RRA-LH/RIA-LH for basal levels (less than 1 ng RIA-LH/ml plasma) was 17.8 as compared to a mean ratio for higher peak values (more than 20 ng RIA-LH/ml plasma) of only 1.2. (author)

Technological change in energy systems. Learning curves, logistic curves and input-output coefficients

International Nuclear Information System (INIS)

Pan, Haoran; Koehler, Jonathan

2007-01-01

Learning curves have recently been widely adopted in climate-economy models to incorporate endogenous change of energy technologies, replacing the conventional assumption of an autonomous energy efficiency improvement. However, there has been little consideration of the credibility of the learning curve. The current trend that many important energy and climate change policy analyses rely on the learning curve means that it is of great importance to critically examine the basis for learning curves. Here, we analyse the use of learning curves in energy technology, usually implemented as a simple power function. We find that the learning curve cannot separate the effects of price and technological change, cannot reflect continuous and qualitative change of both conventional and emerging energy technologies, cannot help to determine the time paths of technological investment, and misses the central role of R and D activity in driving technological change. We argue that a logistic curve of improving performance modified to include R and D activity as a driving variable can better describe the cost reductions in energy technologies. Furthermore, we demonstrate that the top-down Leontief technology can incorporate the bottom-up technologies that improve along either the learning curve or the logistic curve, through changing input-output coefficients. An application to UK wind power illustrates that the logistic curve fits the observed data better and implies greater potential for cost reduction than the learning curve does. (author)

Trends in adult leukemia incidence and survival in Denmark, 1943-2003

DEFF Research Database (Denmark)

Thygesen, Lau Caspar; Nielsen, Ove Juul; Johansen, Christoffer

2009-01-01

The etiology of leukemia is largely unknown. Ecological data indicating trends in incidence and survival can provide information about changes in risk factors, can reflect underlying changes in diagnostic classification, and can measure therapeutic advances. From the records of the Danish Cancer...... Registry with registration starting from 1943, we calculated age-specific, period-specific, and age-standardized (world standard) incidence rates of chronic lymphoid leukemia (CLL), acute lymphoid leukemia (ALL), chronic myeloid leukemia (CML), and acute myeloid leukemia (AML) for persons above the age...... of 18. Kaplan-Meier survival curves and median survival times were calculated. Between 1943 and 2003, there were 26,036 cases of leukemia reported. The age-specific incidence rates of CLL, CML, and AML were higher for older men and women, while the incidence rates of ALL by age were more homogeneous...

Dose-response calibration curves of {sup 137}Cs gamma rays for dicentric chromosome aberrations in human lymphocytes

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Jo, Wol Soon; Oh, Su Jung; Jeong, Soo Kyun; Yang, Kwang Mo [Dept. of Research center, Dong Nam Institute of Radiological and Medical Sciences, Busan (Korea, Republic of); Jeong, Min Ho [Dept. of Microbiology, Dong A University College of Medicine, Busan (Korea, Republic of)

2012-11-15

Recently, the increased threat of radiologically industrial accident such as radiation nondestructive inspection or destruction of nuclear accident by natural disaster such as Fukushima accident requires a greater capacity for cytogenetic biodosimetry, which is critical for clinical triage of potentially thousands of radiation-exposed individuals. Dicentric chromosome aberration analysis is the conventional means of assessing radiation exposure. Dose–response calibration curves for {sup 13}'7Cs gamma rays have been established for unstable chromosome aberrations in human peripheral blood lymphocytes in many laboratories of international biodosimetry network. In this study, therefore, we established dose– response calibration curves of our laboratory for {sup 137}Cs gamma raysaccording to the IAEA protocols for conducting the dicentric chromosome assay We established in vitro dose–response calibration curves for dicentric chromosome aberrations in human lymphocytes for{sup 13}'7Cs gamma rays in the 0 to 5 Gy range, using the maximum likelihood linear-quadratic model, Y = c+αD+βD2. The estimated coefficients of the fitted curves were within the 95% confidence intervals (CIs) and the curve fitting of dose–effect relationship data indicated a good fit to the linear-quadratic model. Hence, meaningful dose estimation from unknown sample can be determined accurately by using our laboratory’s calibration curve according to standard protocol.

Short-term effects of early-acting and multilineage hematopoietic growth factors on the repair and proliferation of irradiated pure cord blood (CB) CD34 hematopoietic progenitor cells

International Nuclear Information System (INIS)

Ziegler, Benedikt L.; Sandor, Peter S.; Plappert, Ulla; Thoma, Stefan; Mueller, Robert; Bock, Thomas; Thomas, Christian A.; Nothdurft, Wilhelm; Fliedner, Theodor M.

1998-01-01

Purpose: Hematopoietic growth factor(s) (GF) may exert positive effects in vitro or in vivo on the survival of hematopoietic stem and progenitor cells after accidental or therapeutic total body irradiation. Methods and Materials: We studied the clonogenic survival and DNA repair of irradiated (0.36, 0.73, and 1.46 Gy) CD34 + cord blood (CB) cells after short-term incubation (24 h) with GFs. CD34 + cells were stimulated with basic fibroblast growth factor (bFGF), stem cell factor/c-kit ligand (SCF), interleukin-3 (IL-3), IL-6, leukemia inhibitory factor (LIF), and granulocyte-monocyte colony stimulating factor (GM-CSF) alone or in combination in short-term serum-free liquid suspension cultures (LSC) immediately after irradiation and then assayed for clonogenic progenitors. DNA repair was evaluated by analysis of DNA strand breaks using the comet assay. Survival of CFU-GM, BFU-E, and CFU-Mix was determined and dose-response curves were fitted to the data. Results: The radiobiological parameters (D 0 and n) showed significant GF(s) effects. Combination of IL-3 with IL-6, SCF or GM-CSF resulted in best survival for CFU-GM BFU-E and CFU-Mix, respectively. Combinations of three or more GFs did not increase the survival of clonogenic CD34 + cells compared to optimal two-factor combinations. The D 0 values for CFU-GM, BFU-E, and CFU-Mix ranged between 0.56-1.15, 0.41-2.24, and 0.56-1.29 Gy, respectively. As for controls, the curves remained strictly exponential, i.e., all survival curves were strictly exponential without any shoulder (extrapolation numbers n = 1 for all tested GF(s). DNA repair capacity of CD34 + cells determined by comet assay, was measured before, immediately after irradiation, as well as 30 and 120 min after irradiation at 1 Gy. Notably, after irradiation the 2-h repair of cytokine-stimulated and unstimulated CD34 + cells was similar. Conclusion: Our data indicate that increased survival of irradiated CB CD34 + cells after short-term GF treatment is

The potential value of the neutral comet assay and the expression of genes associated with DNA damage in assessing the radiosensitivity of tumor cells.

Science.gov (United States)

Jayakumar, Sundarraj; Bhilwade, Hari N; Pandey, Badri N; Sandur, Santosh K; Chaubey, Ramesh C

2012-10-09

The assessment of tumor radiosensitivity would be particularly useful in optimizing the radiation dose during radiotherapy. Therefore, the degree of correlation between radiation-induced DNA damage, as measured by the alkaline and the neutral comet assays, and the clonogenic survival of different human tumor cells was studied. Further, tumor radiosensitivity was compared with the expression of genes associated with the cellular response to radiation damage. Five different human tumor cell lines were chosen and the radiosensitivity of these cells was established by clonogenic assay. Alkaline and neutral comet assays were performed in γ-irradiated cells (2-8Gy; either acute or fractionated). Quantitative PCR was performed to evaluate the expression of DNA damage response genes in control and irradiated cells. The relative radiosensitivity of the cell lines assessed by the extent of DNA damage (neutral comet assay) immediately after irradiation (4Gy or 6Gy) was in agreement with radiosensitivity pattern obtained by the clonogenic assay. The survival fraction of irradiated cells showed a better correlation with the magnitude of DNA damage measured by the neutral comet assay (r=-0.9; Pcomet assay (r=-0.73; Pcomet assay was better than alkaline comet assay for assessment of radiosensitivities of tumor cells after acute or fractionated doses of irradiation. © 2012 Elsevier B.V. All rights reserved.

Development and External Validation of Prognostic Model for 2-Year Survival of Non-Small-Cell Lung Cancer Patients Treated With Chemoradiotherapy

International Nuclear Information System (INIS)

Dehing-Oberije, Cary; Yu Shipeng; De Ruysscher, Dirk; Meersschout, Sabine; Van Beek, Karen; Lievens, Yolande; Van Meerbeeck, Jan; De Neve, Wilfried; Rao, Bharat Ph.D.; Weide, Hiska van der; Lambin, Philippe

2009-01-01

Purpose: Radiotherapy, combined with chemotherapy, is the treatment of choice for a large group of non-small-cell lung cancer (NSCLC) patients. Recent developments in the treatment of these patients have led to improved survival. However, the clinical TNM stage is highly inaccurate for the prediction of survival, and alternatives are lacking. The objective of this study was to develop and validate a prediction model for survival of NSCLC patients, treated with chemoradiotherapy. Patients and Methods: The clinical data from 377 consecutive inoperable NSCLC patients, Stage I-IIIB, treated radically with chemoradiotherapy were collected. A prognostic model for 2-year survival was developed, using 2-norm support vector machines. The performance of the model was expressed as the area under the curve of the receiver operating characteristic and assessed using leave-one-out cross-validation, as well as two external data sets. Results: The final multivariate model consisted of gender, World Health Organization performance status, forced expiratory volume in 1 s, number of positive lymph node stations, and gross tumor volume. The area under the curve, assessed by leave-one-out cross-validation, was 0.74, and application of the model to the external data sets yielded an area under the curve of 0.75 and 0.76. A high- and low-risk group could be clearly identified using a risk score based on the model. Conclusion: The multivariate model performed very well and was able to accurately predict the 2-year survival of NSCLC patients treated with chemoradiotherapy. The model could support clinicians in the treatment decision-making process.

Survival and reproduction of small hive beetle (Coleoptera: Nitidulidae) on commercial pollen substitutes

Science.gov (United States)

An assay was developed to investigate the small hive beetle’s (Aethina tumida) potential for survival and reproduction when providing artificial food resources in managed European honey bees (Apis mellifera). Supplemental feeding is done to maintain the health of the hive, initiate comb building, ex...

Revealing the equivalence of two clonal survival models by principal component analysis

International Nuclear Information System (INIS)

Lachet, Bernard; Dufour, Jacques

1976-01-01

The principal component analysis of 21 chlorella cell survival curves, adjusted by one-hit and two-hit target models, lead to quite similar projections on the principal plan: the homologous parameters of these models are linearly correlated; the reason for the statistical equivalence of these two models, in the present state of experimental inaccuracy, is revealed [fr

Can survival prediction be improved by merging gene expression data sets?

Directory of Open Access Journals (Sweden)

Haleh Yasrebi

Full Text Available BACKGROUND: High-throughput gene expression profiling technologies generating a wealth of data, are increasingly used for characterization of tumor biopsies for clinical trials. By applying machine learning algorithms to such clinically documented data sets, one hopes to improve tumor diagnosis, prognosis, as well as prediction of treatment response. However, the limited number of patients enrolled in a single trial study limits the power of machine learning approaches due to over-fitting. One could partially overcome this limitation by merging data from different studies. Nevertheless, such data sets differ from each other with regard to technical biases, patient selection criteria and follow-up treatment. It is therefore not clear at all whether the advantage of increased sample size outweighs the disadvantage of higher heterogeneity of merged data sets. Here, we present a systematic study to answer this question specifically for breast cancer data sets. We use survival prediction based on Cox regression as an assay to measure the added value of merged data sets. RESULTS: Using time-dependent Receiver Operating Characteristic-Area Under the Curve (ROC-AUC and hazard ratio as performance measures, we see in overall no significant improvement or deterioration of survival prediction with merged data sets as compared to individual data sets. This apparently was due to the fact that a few genes with strong prognostic power were not available on all microarray platforms and thus were not retained in the merged data sets. Surprisingly, we found that the overall best performance was achieved with a single-gene predictor consisting of CYB5D1. CONCLUSIONS: Merging did not deteriorate performance on average despite (a The diversity of microarray platforms used. (b The heterogeneity of patients cohorts. (c The heterogeneity of breast cancer disease. (d Substantial variation of time to death or relapse. (e The reduced number of genes in the merged data

Survival chance in papillary thyroid cancer in Hungary: individual survival probability estimation using the Markov method

International Nuclear Information System (INIS)

Esik, Olga; Tusnady, Gabor; Daubner, Kornel; Nemeth, Gyoergy; Fuezy, Marton; Szentirmay, Zoltan

1997-01-01

Purpose: The typically benign, but occasionally rapidly fatal clinical course of papillary thyroid cancer has raised the need for individual survival probability estimation, to tailor the treatment strategy exclusively to a given patient. Materials and methods: A retrospective study was performed on 400 papillary thyroid cancer patients with a median follow-up time of 7.1 years to establish a clinical database for uni- and multivariate analysis of the prognostic factors related to survival (Kaplan-Meier product limit method and Cox regression). For a more precise prognosis estimation, the effect of the most important clinical events were then investigated on the basis of a Markov renewal model. The basic concept of this approach is that each patient has an individual disease course which (besides the initial clinical categories) is affected by special events, e.g. internal covariates (local/regional/distant relapses). On the supposition that these events and the cause-specific death are influenced by the same biological processes, the parameters of transient survival probability characterizing the speed of the course of the disease for each clinical event and their sequence were determined. The individual survival curves for each patient were calculated by using these parameters and the independent significant clinical variables selected from multivariate studies, summation of which resulted in a mean cause-specific survival function valid for the entire group. On the basis of this Markov model, prediction of the cause-specific survival probability is possible for extrastudy cases, if it is supposed that the clinical events occur within new patients in the same manner and with the similar probability as within the study population. Results: The patient's age, a distant metastasis at presentation, the extent of the surgical intervention, the primary tumor size and extent (pT), the external irradiation dosage and the degree of TSH suppression proved to be

Computerised curve deconvolution of TL/OSL curves using a popular spreadsheet program.

Science.gov (United States)

Afouxenidis, D; Polymeris, G S; Tsirliganis, N C; Kitis, G

2012-05-01

This paper exploits the possibility of using commercial software for thermoluminescence and optically stimulated luminescence curve deconvolution analysis. The widely used software package Microsoft Excel, with the Solver utility has been used to perform deconvolution analysis to both experimental and reference glow curves resulted from the GLOw Curve ANalysis INtercomparison project. The simple interface of this programme combined with the powerful Solver utility, allows the analysis of complex stimulated luminescence curves into their components and the evaluation of the associated luminescence parameters.

Computerised curve deconvolution of TL/OSL curves using a popular spreadsheet program

International Nuclear Information System (INIS)

Afouxenidis, D.; Polymeris, G. S.; Tsirliganis, N. C.; Kitis, G.

2012-01-01

This paper exploits the possibility of using commercial software for thermoluminescence and optically stimulated luminescence curve deconvolution analysis. The widely used software package Microsoft Excel, with the Solver utility has been used to perform deconvolution analysis to both experimental and reference glow curves resulted from the Glow Curve Analysis Intercomparison project. The simple interface of this programme combined with the powerful Solver utility, allows the analysis of complex stimulated luminescence curves into their components and the evaluation of the associated luminescence parameters. (authors)

A standard curve based method for relative real time PCR data processing

Directory of Open Access Journals (Sweden)

Krause Andreas

2005-03-01

Full Text Available Abstract Background Currently real time PCR is the most precise method by which to measure gene expression. The method generates a large amount of raw numerical data and processing may notably influence final results. The data processing is based either on standard curves or on PCR efficiency assessment. At the moment, the PCR efficiency approach is preferred in relative PCR whilst the standard curve is often used for absolute PCR. However, there are no barriers to employ standard curves for relative PCR. This article provides an implementation of the standard curve method and discusses its advantages and limitations in relative real time PCR. Results We designed a procedure for data processing in relative real time PCR. The procedure completely avoids PCR efficiency assessment, minimizes operator involvement and provides a statistical assessment of intra-assay variation. The procedure includes the following steps. (I Noise is filtered from raw fluorescence readings by smoothing, baseline subtraction and amplitude normalization. (II The optimal threshold is selected automatically from regression parameters of the standard curve. (III Crossing points (CPs are derived directly from coordinates of points where the threshold line crosses fluorescence plots obtained after the noise filtering. (IV The means and their variances are calculated for CPs in PCR replicas. (V The final results are derived from the CPs' means. The CPs' variances are traced to results by the law of error propagation. A detailed description and analysis of this data processing is provided. The limitations associated with the use of parametric statistical methods and amplitude normalization are specifically analyzed and found fit to the routine laboratory practice. Different options are discussed for aggregation of data obtained from multiple reference genes. Conclusion A standard curve based procedure for PCR data processing has been compiled and validated. It illustrates that

In vitro assays for predicting tumor cell response to radiation by apoptotic pathways

International Nuclear Information System (INIS)

Algan, Oe.; Hanks, G.E.; Biade, S.; Chapman, J.D.

1995-01-01

were detected by gel electrophoresis procedures but this technique is laborious and difficult to quantify. Centrifugation procedures of irradiation cells which had been pre-labeled with 3 H-thymidine showed ∼18% of total cellular DNA to be fragmented within 12 hr, after which time the extent of DNA fragmentation plateaued. The labeling of 3'-OH ends in cellular DNA by the immunofluorescence reagent, ApopTag[reg], showed ∼15% of cells to undergo apoptotic degradation. Staining of irradiated cells with LIVE/DEAD[reg] EUKOLIGHT TM and trypan blue showed 20-25% cell death. Although the vital stain assays are not specific for apoptosis, the proportion of rapid cell death (within 24-48 hr) which they measure is close to that obtained with the apoptotic-specific assays. These studies indicate that 24 hr after irradiation with 10 Gy, approximately 20% of DU-145 cells undergo death by apoptosis. Survival curves constructed with different radiation doses indicate that this rapid mechanism of cell death follows single-hit kinetics and constitutes between 10-30% of the total α coefficient measured by clonogenic assays with this cell line. Conclusion: Two phases of cell death are observed after ionizing radiation of the DU-145 prostate cancer cell line. Rapid cell death occurs within ∼24 hr and appears to correlate with apoptotic cell death. The vital stains, LIVE/DEAD[reg] EUKOLIGHT TM and trypan blue, yield quantitatively similar estimates of rapid cell killing to the apoptosis-specific assays. We are currently extending these studies to other human prostate tumor cell lines and to tumor cells released from human prostate biopsies. Such assays may provide additional prognostic information for predicting radiotherapy outcome of patients receiving radiotherapy

Insulin-like growth factors: assay methods and their implications

International Nuclear Information System (INIS)

Guyda, H.J.; Posner, B.I.; Schiffrin, A.; Rappaport, R.; Postel-Vinay, M.C.; Corvol, M.T.

1981-01-01

The insulin-like growth factors (IGF's) are small molecular weight peptides (6-10 x 10 3 daltons) that circulate in blood plasma almost entirely bound to macromolecular carrier proteins. The growth-promoting and insulin-like activities of IGF's can be explained by the observed ability of these peptides to interact with the IGF receptor on the one hand and with the insulin receptor on the other. These observations have led to the establishment of radioreceptor assays (RRA's), competitive protein binding assays (CPBA's), and more recently radioimmunoassays (RIA's) for the IGF's that have different specificities. Because of their ease of performance and sensitivity, the radioligand assays have largely supplanted the biological assays originally utilized to identify and characterize these anabolic peptides. In this report the authors' studies are summarised which utilize a slightly acidic IGF which has been purified on the basis of its insulin-like activity in an insulin RRA and which was termed ILAs. They refer to purified insulin-like peptides that have the properties of a somatomedin by the generic term insulin-like growth factor (IGF). Somatomedin (SM) activity will be utilized to connote that activity in plasma or serum determined by bioassay. The competitive dose-response curves for IGF peptides in the insulin RRA as well as those in the ILAs RRA are presented. A combination of bioassays, RRA and RIA were employed to assess somatomedin activity and IGF peptide levels in a number of clinical circumstances. The correlations are discussed. (Auth.)

Individual response to ionising radiation: What predictive assay(s) to choose?

International Nuclear Information System (INIS)

Granzotto, A.; Viau, M.; Devic, C.; Maalouf, M.; Thomas, Ch.; Vogin, G.; Foray, N.; Granzotto, A.; Vogin, G.; Balosso, J.; Joubert, A.; Maalouf, M.; Vogin, G.; Colin, C.; Malek, K.; Balosso, J.; Colin, C.

2011-01-01

Individual response to ionizing radiation is an important information required to apply an efficient radiotherapy treatment against tumour and to avoid any adverse effects in normal tissues. In 1981, Fertil and Malaise have demonstrated that the post-irradiation local tumor control determined in vivo is correlated with clonogenic cell survival assessed in vitro. Furthermore, these authors have reminded the relevance of the concept of intrinsic radiosensitivity that is specific to each individual organ (Fertil and Malaise, 1981) [1]. To date, since clonogenicity assays are too time-consuming and do not provide any other molecular information, a plethora of research groups have attempted to determine the molecular bases of intrinsic radiosensitivity in order to propose reliable and faster predictive assays. To this aim, several approaches have been developed. Notably, the recent revolution in genomic and proteomics technologies is providing a considerable number of data but their link with radiosensitivity still remains to be elucidated. On another hand, the systematic screening of some candidate genes potentially involved in the radiation response is highlighting the complexity of the molecular and cellular mechanisms of DNA damage sensing and signalling and shows that an abnormal radiation response is not necessarily due to the impairment of one single protein. Finally, more modest approaches consisting in focusing some specific functions of DNA repair seem to provide more reliable clues to predict over-acute reactions caused by radiotherapy. In this review, we endeavored to analyse the contributions of these major approaches to predict human radiosensitivity. (authors)

Clinical evaluation of the Byk LIA-mat CA125 II assay: discussion of a reference value.

Science.gov (United States)

Bonfrer, J M; Korse, C M; Verstraeten, R A; van Kamp, G J; Hart, G A; Kenemans, P

1997-03-01

The Byk LIA-mat CA125 II assay was compared with the Centocor IRMA CA125 II. Serum samples studied (n = 1012) were obtained from 652 apparently healthy females, 61 pregnant women, and 299 patients with benign and malignant gynecological tumors. The CA125 II assay value at the 95th percentile of the total healthy group was 29 kU/L for the LIA-mat and 32 kU/L for the Centocor assay. For the LIA-mat assay the 95th percentile was 31 kU/L (Centocor 36 kU/L) for the group 55 years of age. By using ROC curves we found the optimal pretreatment Byk LIA-mat CA125 II value differentiating between benign and malignant ovarian tumors to be 95 kU/L. Pretreatment CA125 values > 1000 kU/L were detected in serum samples of patients with advanced epithelial ovarian cancer.

In vitro radiosensitivity of human fresh T-lymphocytes by colony formation assay using PHA and recombinant Interleukin-2

International Nuclear Information System (INIS)

Tatsugawa, Kaori; Nakamura, Nori; Hakoda, Masayuki; Akiyama, Mitoshi.

1988-05-01

In vitro culture conditions for colony formation of human fresh peripheral T-cells using phytohemagglutinin (PHA) and recombinant Interleukin-2 are defined. Peripheral lymphocytes, from six individuals, were exposed to X or gamma rays in vitro, and dose-survival curves were obtained. The results showed typical sigmoid curves similar to those observed when other mammalian cells are exposed to radiation. The D 10 (dose required to kill 90 % of the cells) was found to be 3.0 to 3.5 Gy. (author)

Genomic instability induced by 137Cs γ-ray irradiation in CHL surviving cells

International Nuclear Information System (INIS)

Yue Jingyin; Liu Bingchen; Wu Hongying; Zhou Jiwen; Mu Chuanjie

1999-01-01

Objective: To study in parallel several possible manifestations of instability of surviving CHL cells after irradiation, namely the frequencies of mutation at locus, micronuclei and apoptosis. Methods: The frequencies of mutation at HGPRT locus, micronuclei and apoptosis were assayed at various times in surviving cells irradiated with γ-rays. Results: The surviving cells showed a persistently increased frequency of mutation at the HGPRT locus after irradiation until 53 days. Mutant fraction as high as 10 -4 was scored, tens of times higher than those assayed in control cells studied in parallel. The frequency of bi nucleated cells with micronuclei determined within 24 hours after irradiation increased with dose and reached a peak value of (26.58 +- 2.48)% at 3 Gy, decreasing at higher doses to a plateau around 20%. The micronucleus frequency decreased steeply to about (14.47 +- 2.39)% within the first 3 days post-irradiation, and fluctuated at around 10% up to 56 days post-irradiation. The delayed efficiency of irradiated cells was significantly decreased. The frequency of apoptosis peaked about (24.90 +- 4.72)% at 10 Gy 48 h post-irradiation (γ-ray dose between 3-10 Gy) and then decreased to about 12% within 3 days. It was significantly higher than in control cells until 14 days. Conclusions: It shows that genomic instability induced by radiation can be transmitted to the progeny of surviving cells and may take many forms of expression such as lethal mutation, chromosome aberrations, gene mutation, etc

Survival of parenchymal hepatocytes exposed to 14.3-MeV neutrons

International Nuclear Information System (INIS)

Jirtle, R.L.; Gould, M.N.; DeLuca, P.M. Jr.; Pearson, D.W.

1982-01-01

This report presents the results of the measurement of a dose survival curve and RBE values for rat hepatic cells irradiated in vivo with 14.3 MeV neutrons. The purpose was to determine the RBE for neutrons as a function of dose, and whether hepatocytes exposed to neutrons are as efficient at repairing potentially lethal damage as they are after exposure to low LET radiation

Correlation of the microculture-kinetic drug-induced apoptosis assay with patient outcomes in initial treatment of adult acute myelocytic leukemia.

Science.gov (United States)

Strickland, Stephen A; Raptis, Anastasios; Hallquist, Allan; Rutledge, James; Chernick, Michael; Perree, Mathieu; Talbott, Mahsa S; Presant, Cary A

2013-03-01

Overall survival (OS) with acute myeloid leukemia (AML) remains poor. Determining prognostic factors will help in selecting patients for appropriate treatments. Our aim was to determine whether the level of drug-induced apoptosis (chemosensitivity) demonstrated by the microculture-kinetic drug-induced apoptosis (MiCK) assay significantly predicted outcomes after standard AML induction therapy. A total of 109 patients with untreated AML had blood and/or bone marrow aspirate samples analyzed for anthracycline-induced apoptosis using the MiCK assay. The amount of apoptosis observed over 48 h was determined and expressed as kinetic units of apoptosis (KU). Complete remission (CR) was significantly higher (72%) in patients with high idarubicin-induced apoptosis >3 KU compared to patients with apoptosis ≤ 3 KU (p = 0.01). Multivariate analysis showed the only significant variables to be idarubicin-induced apoptosis and karyotype. Median overall survival of patients with idarubicin-induced apoptosis >3 KU was 16.1 months compared to 4.5 months in patients with apoptosis ≤ 3 KU (p = 0.004). Multivariate analysis showed the only significant variable to be idarubicin-induced apoptosis. Chemotherapy-induced apoptosis measured by the MiCK assay demonstrated significant correlation with outcomes and appears predictive of complete remission and overall survival for patients receiving standard induction chemotherapy.

Association of ultraviolet-induced retrovirus expression with anchorage-independent survival in rat embryo cells

International Nuclear Information System (INIS)

Suk, W.A.

1985-01-01

The authors have shown in the AI assay that the nontransforming retrovirus increases the differential in enhanced survival response in infected cultures. To more fully understand this aspect of the system, they examined the effect of UV irradiation on infected and uninfected FRE cells. In this communication the authors report that UV irradiation induces AI survival in infected and uninfected cells;in uninfected cells there is a concomitant induction of endogenous retrovirus expression. The AI survival of both cell lines was determined using a previously described procedure. Anchorage-dependent media control and solvent control cells, when suspended in medium above an agar base layer, showed a rapid decline in cell survival;however, cells that had been treated with carcinogen did not undergo the destructive process that took place in control cells, indicating specificity

Approximation by planar elastic curves

DEFF Research Database (Denmark)

Brander, David; Gravesen, Jens; Nørbjerg, Toke Bjerge

2016-01-01

We give an algorithm for approximating a given plane curve segment by a planar elastic curve. The method depends on an analytic representation of the space of elastic curve segments, together with a geometric method for obtaining a good initial guess for the approximating curve. A gradient......-driven optimization is then used to find the approximating elastic curve....

Administration of polysaccharide from Panax notoginseng prolonged the survival of H22 tumor-bearing mice

Directory of Open Access Journals (Sweden)

Li HY

2016-06-01

Full Text Available Huaiyu Li,1,* Longlong Gu,1,2,* Yuanyuan Zhong,1 Yajuan Chen,1 Lei Zhang,1 Annie R Zhang,3 Robert W Sobol,4,5 Tong Chen,1,6 Jianfeng Li4,5 1Yunnan Key Laboratory of Pharmacology for Natural Products, School of Pharmaceutical Sciences, 2Haiyuan College, Kunming Medical University, Kunming, Yunnan, People’s Republic of China; 3Graduate School of Applied and Professional Psychology, Rutgers, The State University of New Jersey, Piscataway, NJ, 4Department of Oncologic Sciences, 5Mitchell Cancer Institute, University of South Alabama, Mobile, AL, USA; 6Yunnan Panax notoginseng (Burk F.H. Chen Biotechnology and Pharmaceutical Engineering Research Center, Kunming, Yunnan, People’s Republic of China *These authors contributed equally to this work Background: Polysaccharides from various sources are being considered potential sources for the treatment of liver cancer. The aim of this study was to investigate the impact of polysaccharide isolated from Panax notoginseng (PPN on the proliferation of H22 liver cancer cells and the survival of the tumor-bearing mice transplanted with H22 cells.Materials and methods: Polysaccharide from PPN was added to the culture medium of mouse hepatoma H22 cells at different doses. Cell proliferation was assayed with a standard MTT assay. Survival rates of tumor-bearing mice were recorded. Peripheral blood lymphocytes were assayed by flow cytometry. Serum interleukin-2 levels in peripheral blood were measured by enzyme-linked immunosorbent assay.Results: Polysaccharide from PPN inhibited the growth of H22 cells and significantly prolonged the survival of tumor-bearing mice. The increase in activated CD4+ T-cells and the elevation of serum interleukin-2 may contribute to the antitumor activity of PPN.Conclusion: PPN has potential antitumor activity for the treatment of liver cancer. Keywords: polysaccharide, Panax notoginseng, liver cancer, immunotherapy, IL-2

Variation in assessment of oxidatively damaged DNA in mononuclear blood cells by the comet assay with visual scoring

DEFF Research Database (Denmark)

Forchhammer, Lykke; Bräuner, Elvira Vaclavik; Folkmann, Janne Kjaersgaard

2008-01-01

The comet assay is popular for assessments of genotoxicity, but the comparison of results between studies is challenging because of differences in experimental procedures and reports of DNA damage in different units. We investigated the variation of DNA damage in mononuclear blood cells (MNBCs......) measured by the comet assay with focus on the variation related to alkaline unwinding and electrophoresis time, number of cells scored, as well as the putative benefits of transforming the primary end points to common units by the use of reference standards and calibration curves. Eight experienced......, our results indicate that inter-investigator difference in scoring is a strong determinant of DNA damage levels measured by the comet assay....

Respiratory activity as a determinant of radiation survival response

Energy Technology Data Exchange (ETDEWEB)

Bruce, A K; Berner, J D [State Univ. of New York, Buffalo (USA). Dept. of Biology

1976-09-01

Respiration is depressed in irradiated bacteria reaching a minimum level in most strains at 1-3 h after exposure when incubated in growth medium. Since a delay in response is observed, direct action on respiratory enzymes is unlikely. The dosage response of respiration varies widely in the strains studied. All strains exhibit two-component dosage-response curves. The facts suggest that respiration is a major factor in influencing cell survival and may be the principal mechanism through which chemical agents modify radiation response.

Bragg Curve Spectroscopy

International Nuclear Information System (INIS)

Gruhn, C.R.

1981-05-01

An alternative utilization is presented for the gaseous ionization chamber in the detection of energetic heavy ions, which is called Bragg Curve Spectroscopy (BCS). Conceptually, BCS involves using the maximum data available from the Bragg curve of the stopping heavy ion (HI) for purposes of identifying the particle and measuring its energy. A detector has been designed that measures the Bragg curve with high precision. From the Bragg curve the range from the length of the track, the total energy from the integral of the specific ionization over the track, the dE/dx from the specific ionization at the beginning of the track, and the Bragg peak from the maximum of the specific ionization of the HI are determined. This last signal measures the atomic number, Z, of the HI unambiguously

Injury risk curves for the WorldSID 50th male dummy.

Science.gov (United States)

Petitjean, Audrey; Trosseille, Xavier; Petit, Philippe; Irwin, Annette; Hassan, Joe; Praxl, Norbert

2009-11-01

logistic regression, the survival analysis and the Consistent Threshold Estimate. The paper presents the methods used to check and process the data, select the PMHS tests, and construct the injury risk curves. The PMHS dataset as well as the injury risk curves are provided.

Learning Curve? Which One?

Directory of Open Access Journals (Sweden)

Paulo Prochno

2004-07-01

Full Text Available Learning curves have been studied for a long time. These studies provided strong support to the hypothesis that, as organizations produce more of a product, unit costs of production decrease at a decreasing rate (see Argote, 1999 for a comprehensive review of learning curve studies. But the organizational mechanisms that lead to these results are still underexplored. We know some drivers of learning curves (ADLER; CLARK, 1991; LAPRE et al., 2000, but we still lack a more detailed view of the organizational processes behind those curves. Through an ethnographic study, I bring a comprehensive account of the first year of operations of a new automotive plant, describing what was taking place on in the assembly area during the most relevant shifts of the learning curve. The emphasis is then on how learning occurs in that setting. My analysis suggests that the overall learning curve is in fact the result of an integration process that puts together several individual ongoing learning curves in different areas throughout the organization. In the end, I propose a model to understand the evolution of these learning processes and their supporting organizational mechanisms.

Contractibility of curves

Directory of Open Access Journals (Sweden)

Janusz Charatonik

1991-11-01

Full Text Available Results concerning contractibility of curves (equivalently: of dendroids are collected and discussed in the paper. Interrelations tetween various conditions which are either sufficient or necessary for a curve to be contractible are studied.

Gold Nanoparticle-Aptamer-Based LSPR Sensing of Ochratoxin A at a Widened Detection Range by Double Calibration Curve Method.

Science.gov (United States)

Liu, Boshi; Huang, Renliang; Yu, Yanjun; Su, Rongxin; Qi, Wei; He, Zhimin

2018-01-01

Ochratoxin A (OTA) is a type of mycotoxin generated from the metabolism of Aspergillus and Penicillium , and is extremely toxic to humans, livestock, and poultry. However, traditional assays for the detection of OTA are expensive and complicated. Other than OTA aptamer, OTA itself at high concentration can also adsorb on the surface of gold nanoparticles (AuNPs), and further inhibit AuNPs salt aggregation. We herein report a new OTA assay by applying the localized surface plasmon resonance effect of AuNPs and their aggregates. The result obtained from only one single linear calibration curve is not reliable, and so we developed a "double calibration curve" method to address this issue and widen the OTA detection range. A number of other analytes were also examined, and the structural properties of analytes that bind with the AuNPs were further discussed. We found that various considerations must be taken into account in the detection of these analytes when applying AuNP aggregation-based methods due to their different binding strengths.

Roc curves for continuous data

CERN Document Server

Krzanowski, Wojtek J

2009-01-01

Since ROC curves have become ubiquitous in many application areas, the various advances have been scattered across disparate articles and texts. ROC Curves for Continuous Data is the first book solely devoted to the subject, bringing together all the relevant material to provide a clear understanding of how to analyze ROC curves.The fundamental theory of ROC curvesThe book first discusses the relationship between the ROC curve and numerous performance measures and then extends the theory into practice by describing how ROC curves are estimated. Further building on the theory, the authors prese

Differentiation of five enterohepatic Helicobacter species by nested PCR with high-resolution melting curve analysis.

Science.gov (United States)

Wu, Miaoli; Rao, Dan; Zhu, Yujun; Wang, Jing; Yuan, Wen; Zhang, Yu; Huang, Ren; Guo, Pengju

2017-04-01

Enterohepatic Helicobacter species (EHS) are widespread in rodent species around the world. Several studies have demonstrated that infection with EHS can interfere with the outcomes of animal experiments in cancer research and significantly influence the study results. Therefore, it is essential to establish a rapid detection and identification of EHS for biomedical research using laboratory rodents. Our study aimed to develop a rapid and sensitive method to detect and distinguish five enterohepatic Helicobacter species. Nested PCR followed by high-resolution melting curve analysis (HRM) was developed for identification of H. bilis, H. rodentium, H. muridarum, H. typhlonius, as well as H. hepaticus. To validate the accuracy of nested PCR-HRM analysis, quantitative real-time PCR methods for five different enterohepatic Helicobacter species were developed. A total of 50 cecal samples were tested using both nested PCR-HRM analysis and qPCR method. The nested PCR-HRM method could distinguish five enterohepatic Helicobacter species by different melting temperatures. The melting curve were characterized by peaks of 78.7 ± 0.12°C for H. rodentium, 80.51 ± 0.09°C for H. bilis, 81.6 ± 0.1°C for H. typhlonius, 82.11 ± 0.18°C for H. muridarum, and 82.95 ± 0.09°C for H. hepaticus. The nested PCR-HRM assay is a simple, rapid, and cost-effective assay. This assay could be a useful tool for molecular epidemiology study of enterohepatic Helicobacter infection and an attractive alternative for genotyping of enterohepatic Helicobacter species. © 2016 John Wiley & Sons Ltd.

Prognostic and survival analysis of 837 Chinese colorectal cancer patients.

Science.gov (United States)

Yuan, Ying; Li, Mo-Dan; Hu, Han-Guang; Dong, Cai-Xia; Chen, Jia-Qi; Li, Xiao-Fen; Li, Jing-Jing; Shen, Hong

2013-05-07

To develop a prognostic model to predict survival of patients with colorectal cancer (CRC). Survival data of 837 CRC patients undergoing surgery between 1996 and 2006 were collected and analyzed by univariate analysis and Cox proportional hazard regression model to reveal the prognostic factors for CRC. All data were recorded using a standard data form and analyzed using SPSS version 18.0 (SPSS, Chicago, IL, United States). Survival curves were calculated by the Kaplan-Meier method. The log rank test was used to assess differences in survival. Univariate hazard ratios and significant and independent predictors of disease-specific survival and were identified by Cox proportional hazard analysis. The stepwise procedure was set to a threshold of 0.05. Statistical significance was defined as P analysis suggested age, preoperative obstruction, serum carcinoembryonic antigen level at diagnosis, status of resection, tumor size, histological grade, pathological type, lymphovascular invasion, invasion of adjacent organs, and tumor node metastasis (TNM) staging were positive prognostic factors (P analysis showed a significant statistical difference in 3-year survival among these groups: LNR1, 73%; LNR2, 55%; and LNR3, 42% (P analysis results showed that histological grade, depth of bowel wall invasion, and number of metastatic lymph nodes were the most important prognostic factors for CRC if we did not consider the interaction of the TNM staging system (P < 0.05). When the TNM staging was taken into account, histological grade lost its statistical significance, while the specific TNM staging system showed a statistically significant difference (P < 0.0001). The overall survival of CRC patients has improved between 1996 and 2006. LNR is a powerful factor for estimating the survival of stage III CRC patients.

Chordoma: review of clinico radiological features and factors affecting survival

International Nuclear Information System (INIS)

Soo, M.Y.S.

2001-01-01

This study reviews the clinico radiological features of cranial and sacrospinal chordomas and identifies factors affecting survival. Nineteen patients seen between January 1980 and December 2000 with histopathological diagnosis of chordomas were retrospectively reviewed with reference to clinical presentation, imaging features, treatment modalities and post-therapy status. Eight had tumours in the skull base while 11 patients had spinal and sacro-coccygeal lesions. Surgical resection was performed in 16 patients whose subsequent natural history was used to identify clinical indicators that may influence survival. Completeness of resection, age, gender and postoperative irradiation were subjected to analysis using the Cox proportional hazard models. Kaplan-Meir survival curves illustrate the survival distributions. Diplopia and facial pain are prime clinical presentations in cranial lesions, while extremity weakness and a sacrogluteal mass are common complaints in the sacrospinal group. Lesional calcifications are present in 40% while an osteolytic soft tissue mass is detectable by CT in all cases. Heterogeneous signals and internal septations on T 2 -weighted MRI are predominant features. In sacrospinal tumours, complete excision with adjuvant radiotherapy achieves the best results with a disease-free survival of more than 5 years. The clinical and imaging findings in this study are in accordance with those of other series. Except for complete surgical excision followed by radiotherapy in the subset of patients with sacrospinal tumours, none of the other clinical indicators show a statistical significant influence on survival. Copyright (2001) Blackwell Science Pty Ltd

Injury risk curves for the skeletal knee-thigh-hip complex for knee-impact loading.

Science.gov (United States)

Rupp, Jonathan D; Flannagan, Carol A C; Kuppa, Shashi M

2010-01-01

Injury risk curves for the skeletal knee-thigh-hip (KTH) relate peak force applied to the anterior aspect of the flexed knee, the primary source of KTH injury in frontal motor-vehicle crashes, to the probability of skeletal KTH injury. Previous KTH injury risk curves have been developed from analyses of peak knee-impact force data from studies where knees of whole cadavers were impacted. However, these risk curves either neglect the effects of occupant gender, stature, and mass on KTH fracture force, or account for them using scaling factors derived from dimensional analysis without empirical support. A large amount of experimental data on the knee-impact forces associated with KTH fracture are now available, making it possible to estimate the effects of subject characteristics on skeletal KTH injury risk by statistically analyzing empirical data. Eleven studies were identified in the biomechanical literature in which the flexed knees of whole cadavers were impacted. From these, peak knee-impact force data and the associated subject characteristics were reanalyzed using survival analysis with a lognormal distribution. Results of this analysis indicate that the relationship between peak knee-impact force and the probability of KTH fracture is a function of age, total body mass, and whether the surface that loads the knee is rigid. Comparisons between injury risk curves for the midsize adult male and small adult female crash test dummies defined in previous studies and new risk curves for these sizes of occupants developed in this study suggest that previous injury risk curves generally overestimate the likelihood of KTH fracture at a given peak knee-impact force. Future work should focus on defining the relationships between impact force at the human knee and peak axial compressive forces measured by load cells in the crash test dummy KTH complex so that these new risk curves can be used with ATDs.

A comparative study in three commercial kits of radioligand assay for GAD-Ab

International Nuclear Information System (INIS)

Yang Yehua; Zhou Zhiguang; Huang Gan; Yang Feike; Li Zhangwei

2006-01-01

Objective: To provide data for perfect selection of glutamic acid decarboxylase antibodies (GAD-Ab) assay commercial kits. Methods: The sera of 88 titer-graded samples by radioligand assay (RLA) were measured with two types of enzyme-linked immunosorbent assay (ELISA) kits and one type of immunoradiometric assay (IRMA) kit for GAD-Ab in order to test their consistency with RLA. Another 140 diabetic sera were measured with RLA and screened by a type of suitable kit to search the cutoff point for discriminating patients who needed rechecking. Results: Compared with RLA, concordance ratio of 3 kits: Medizym kit(75%) > RSR kit(73.9%) > Biomerica kit(62.5%); Kappa value: Medizym kit (0.408, common) > RSR kit (0.405, common) > Biomerica kit (0.185, failing); correlation to RLA index: RSR kit (r= 0.992) > Medizym kit(r= 0. 791 ) > Biomerica kit (r = -0. 055); area under the receiver operating characteristic (ROC) curve: Medizym kit (0.812) > RSR kit (0. 727 ) > Biomerica kit (0.666). Conclusions: The efficiencies of RSR kit and Medizym kit are good. Serum concentration between 0.25-0.99 U/ml measured by RSR kit is suggested to further recheck by RLA. (authors)

Microfludic device for creating ionic strength gradients over DNA microarrays for efficient DNA melting studies and assay development

DEFF Research Database (Denmark)

Petersen, Jesper; Poulsen, Lena; Birgens, Henrik

2009-01-01

microfluidic device that creates a gradient comprising zones of defined ionic strength over a glass slide, in which each zone corresponds to a subarray. Using this device, we demonstrated that ionic strength gradients function in a similar fashion as corresponding thermal gradients in assay development. More...... specifically, we noted that (i) the two stringency modulators generated melting curves that could be compared, (ii) both led to increased assay robustness, and (iii) both were associated with difficulties in genotyping the same mutation. These findings demonstrate that ionic strength stringency buffers can...

Atlas of stress-strain curves

CERN Document Server

2002-01-01

The Atlas of Stress-Strain Curves, Second Edition is substantially bigger in page dimensions, number of pages, and total number of curves than the previous edition. It contains over 1,400 curves, almost three times as many as in the 1987 edition. The curves are normalized in appearance to aid making comparisons among materials. All diagrams include metric (SI) units, and many also include U.S. customary units. All curves are captioned in a consistent format with valuable information including (as available) standard designation, the primary source of the curve, mechanical properties (including hardening exponent and strength coefficient), condition of sample, strain rate, test temperature, and alloy composition. Curve types include monotonic and cyclic stress-strain, isochronous stress-strain, and tangent modulus. Curves are logically arranged and indexed for fast retrieval of information. The book also includes an introduction that provides background information on methods of stress-strain determination, on...

Tornado-Shaped Curves

Science.gov (United States)

Martínez, Sol Sáez; de la Rosa, Félix Martínez; Rojas, Sergio

2017-01-01

In Advanced Calculus, our students wonder if it is possible to graphically represent a tornado by means of a three-dimensional curve. In this paper, we show it is possible by providing the parametric equations of such tornado-shaped curves.

New fluorimetric assay of horseradish peroxidase using sesamol as substrate and its application to EIA

Directory of Open Access Journals (Sweden)

Hidetoshi Arakawa

2012-04-01

Full Text Available Horseradish peroxidase (HRP is generally used as a label enzyme in enzyme immunoassay (EIA. The procedure used for HRP detection in EIA is critical for sensitivity and precision. This paper describes a novel fluorimetric assay for horseradish peroxidase (HRP using sesamol as substrate. The principle of the assay is as follow: sesamol (3,4-methylenedioxy phenol is reacted enzymatically in the presence of hydrogen peroxide to produce dimeric sesamol. The dimer is fluorescent and can be detected sensitively at ex. 347 nm, em. 427 nm.The measurable range of HRP was 1.0×10−18 to 1.0×10−15 mol/assay, with a detection limit of 1.0×10−18 mol/assay. The coefficient of variation (CV, n=8 was examined at each point on the standard curve, with a mean CV percentage of 3.8%. This assay system was applied to thyroid stimulating hormone (TSH EIA using HRP as the label enzyme. Keywords: Sesamol, Fluorescence, Enzyme immunoassay (EIA, Horseradish peroxidase (HRP, Thyroid stimulating hormone (TSH

Two new automated, compared with two enzyme-linked immunosorbent, antimüllerian hormone assays.

Science.gov (United States)

Nelson, Scott M; Pastuszek, Ewa; Kloss, Grzegorz; Malinowska, Iwona; Liss, Joanna; Lukaszuk, Aron; Plociennik, Lukasz; Lukaszuk, Krzysztof

2015-10-01

To compare new automated antimüllerian hormone (AMH) assay performance characteristics from the new automated Elecsys AMH (Roche; Elecsys) and Access AMH (Beckman Coulter; Access) assays with the existing AMH Gen II ELISA (enzyme-linked immunosorbent assay; Gen II; Beckman Coulter) and AMH ELISA (Ansh Labs) assays. Prospective assay evaluation. University-affiliated clinical chemistry laboratory. Patients referred for serum AMH measurement (n = 83) before start of in vitro fertilization cycle between September 2014 and October 2014. None. Serum AMH concentration. Intra-assay coefficients of variation were low; Ansh ≤ 9.0%; Gen II ≤ 5.8%; Access ≤ 10.7%; and Elecsys ≤ 2.8%. The Passing-Bablok regression equations (pmol/L) were y (Access) = 0.128 + (0.781 × Gen II); and y (Access) = 0.302 + (0.742 x Ansh). For y (Elecys) = 0.087 + (0.729 x Gen II) and y (Elecys) = 0.253 + (0.688 x Ansh Labs). For y (Elecys) = 0.943 - (0.037 × Access). For all the assays, AMH exhibited a moderate positive correlation with AFC (r = 0.62-0.64); number of cumulus oocyte complexes (r = 0.60-0.64); and metaphase II oocytes (r = 0.48-0.50). Accuracy of pregnancy prediction, as determined by area under the receiver operating characteristic curve, was uniformly low for all assays (0.62-0.63). The novel automated assays exhibit strong concordance in calibration, but derived values are substantially lower than those obtained from pre-existing assays, with assay-specific interpretation required for routine clinical use. These results highlight the need for an international standard of measurement of AMH. Copyright © 2015 American Society for Reproductive Medicine. Published by Elsevier Inc. All rights reserved.

A versatile curve-fit model for linear to deeply concave rank abundance curves

NARCIS (Netherlands)

Neuteboom, J.H.; Struik, P.C.

2005-01-01

A new, flexible curve-fit model for linear to concave rank abundance curves was conceptualized and validated using observational data. The model links the geometric-series model and log-series model and can also fit deeply concave rank abundance curves. The model is based ¿ in an unconventional way

Survival and DNA repair in ultraviolet-irradiated haploid and diploid cultured frog cells

International Nuclear Information System (INIS)

Freed, J.J.; Hoess, R.H.; Angelosanto, F.A.; Massey, H.C. Jr.

1979-01-01

Survival and repair of DNA following ultraviolet (254-nm) radiation have been investigated in ICR 2A, a cultured cell line from haploid embryos of the grassfrog, Rana pipiens. Survival curves from cells recovering in the dark gave mean lethal dose value (D 0 ) in the range 1.5-1.7 Jm -2 for both haploid and diploid cell stocks. The only significant difference observed between haploids and diploids was in the extent of the shoulder at low fluence (Dsub(q)), the value for exponentially multiplying diploid cells (3.0 Jm -2 ) being higher than that found for haploids (1.2 Jm -2 ). Irradiation of cultures reversibly blocked in the G1 phase of the cell cycle gave survival-curve coefficients indistinguishable between haploids and diploids. Post-irradiation exposure to visible light restored colony-forming capacity and removed chromatographically estimated pyrimidine dimers from DNA at the same rates. After fluences killing 90% of the cells, complete restoration of survival was obtained after 60-min exposure to 500 foot-candles, indicating that in this range lethality is entirely photoreversible and therefore attributable to pyrimidine dimers in DNA. Dimer removal required illumination following ultraviolet exposure, intact cells and physiological temperature, implying that the photoreversal involved DNA photolyase activity. Excision-repair capacity was slight, since no loss of dimers could be detected chromoatographically during up to 48 h incubation in the dark and since autoradiographically detected 'unscheduled DNA synthesis' was limited to a 2-fold increase saturated at 10 Jm -2 . These properties make ICR 2A frog cells useful to explore how DNA-repair pathways influence mutant yield. (Auth.)

Survival prediction of trauma patients: a study on US National Trauma Data Bank.

Science.gov (United States)

Sefrioui, I; Amadini, R; Mauro, J; El Fallahi, A; Gabbrielli, M

2017-12-01

Exceptional circumstances like major incidents or natural disasters may cause a huge number of victims that might not be immediately and simultaneously saved. In these cases it is important to define priorities avoiding to waste time and resources for not savable victims. Trauma and Injury Severity Score (TRISS) methodology is the well-known and standard system usually used by practitioners to predict the survival probability of trauma patients. However, practitioners have noted that the accuracy of TRISS predictions is unacceptable especially for severely injured patients. Thus, alternative methods should be proposed. In this work we evaluate different approaches for predicting whether a patient will survive or not according to simple and easily measurable observations. We conducted a rigorous, comparative study based on the most important prediction techniques using real clinical data of the US National Trauma Data Bank. Empirical results show that well-known Machine Learning classifiers can outperform the TRISS methodology. Based on our findings, we can say that the best approach we evaluated is Random Forest: it has the best accuracy, the best area under the curve, and k-statistic, as well as the second-best sensitivity and specificity. It has also a good calibration curve. Furthermore, its performance monotonically increases as the dataset size grows, meaning that it can be very effective to exploit incoming knowledge. Considering the whole dataset, it is always better than TRISS. Finally, we implemented a new tool to compute the survival of victims. This will help medical practitioners to obtain a better accuracy than the TRISS tools. Random Forests may be a good candidate solution for improving the predictions on survival upon the standard TRISS methodology.

Concepts for the assay of unbound thyroxine (FT4) and thyroxine binding globulin (TBG)

International Nuclear Information System (INIS)

Odstrchel, G.; Hertl, W.; Ward, F.B.; Travis, K.; Lindner, R.E.; Mason, R.D.

1977-01-01

Two new concepts for the assay of thyroid related substances are presented. One assay (FT 4 ) is based on a kinetic measurement of T 4 as it desorbs from binder proteins onto solid-phase T 4 antibody. This reaction can be described by a second order rate equation; r = k (IMA) (FT 4 ). The assay is rapid (2 hours) and gives good agreement (sigma = 0.92) with equilibrium dialysis and a normal range of 0.9 - 2.3 ng/dl. This assay uses a small sample size (25 μl) and is unaffected by drugs such as aspirin and dilantin. Pregnant and estrogen treated women gave normal FT 4 values. A new method for the measurement of functionally active TEG is also presented. In this case the labeled T 4 is partitioned between bovine serum albumin and the patient's samples. The complex is then removed from solution by solid-phase anti-TBG. A curve remiscent of an immunoradiometric assay is obtained. The assay has a sensitivity of 4 μg/ml and is unaffected by aspirin, dilantin or the patient's T 4 concentrations. Correlation with 'rocket' electrophoresis is 0.90. The normal range was 20 +- 7 μg/ml with pregnant women giving values greater than 30 μg/ml. Five hereditary deficient patients gave a value equivalent to zero TBG concentration. (orig.) [de

In-Vehicle Dynamic Curve-Speed Warnings at High-Risk Rural Curves

Science.gov (United States)

2018-03-01

Lane-departure crashes at horizontal curves represent a significant portion of fatal crashes on rural Minnesota roads. Because of this, solutions are needed to aid drivers in identifying upcoming curves and inform them of a safe speed at which they s...

Effects of hyperthermia and radiation on mouse testis stem cells

International Nuclear Information System (INIS)

Reid, B.O.; Mason, K.A.; Withers, H.R.; West, J.

1981-01-01

The response of mouse testis stem cells to hyperthermia and combined hyperthermia-radiation treatments was assayed by spermatogenic colony regrowth, sperm head counts, testis weight loss, and fertility. With the use of spermatogenic colony assay, thermal enhancement ratios at an isosurvival level of 0.1 were 1.27 at 41 degrees, 1.80 at 42 degrees, and 3.97 at 43 degrees for testes exposed to heat for 30 min prior to irradiation. Sperm head counts were reduced by heat alone from a surviving fraction of 0.58 at 41 degrees to 0.003 at 42.5-43.5 degrees. Curves for sperm head survival measured 56 days after the testes had been heated for 30 min prior to irradiation were biphasic and showed a progressive downward displacement to lower survival with increasing temperature. The 41, 42, and 43 degrees curves were displaced downward by factors of 2, 58, and 175, respectively. The proportion of animals remaining sterile after 30 min of heat (41-43 degrees) and the median sterility period in days increased with increasing temperature. The minimum sperm count necessary to regain fertility was 13% of the normal mouse level

Variation in the measurement of DNA damage by comet assay measured by the ECVAG dagger inter-laboratory validation trial

DEFF Research Database (Denmark)

Forchhammer, Lykke; Johansson, Clara; Loft, Steffen

2010-01-01

the level of DNA damage in monocyte-derived THP-1 cells by either visual classification or computer-aided image analysis of pre-made slides, coded cryopreserved samples of cells and reference standard cells (calibration curve samples). The reference standard samples were irradiated with ionizing radiation...... by the different laboratories as evidenced by an inter-laboratory coefficient of variation (CV) of 47%. Adjustment of the primary comet assay end points by a calibration curve prepared in each laboratory reduced the CV to 28%, a statistically significant reduction (P test). A large fraction...

Effects of ultraviolet radiation on the survival and metabolic end products of Bacteroides melaninogenicus

International Nuclear Information System (INIS)

Smith-Kappus, S.D.

1987-01-01

In experiments investigating DNA repair, it was shown that B. melaninogenicus does not repair UV light induced damage via photoreactivation. Survival curves constructed for the organism after exposure to UV light at 254 nm and 365 nm under aerobic and anaerobic conditions while the organisms were in exponential or stationary growth phase, revealed that the cells were most sensitive to UV induced damage when exposed to radiation while in the exponential growth phase under aerobic conditions at either wavelength. B. melaninogenicus exposed to UV light under anaerobic conditions while the cells were in stationary growth phase were much more sensitive to UV induced damage at 254 nm than cells irradiated under the same conditions at 365 nm UV. Survival studies of B. melaninogenicus after co-insult with UV light and subinhibitory concentrations of chloramphenicol, metronidazole, caffeine, or fluoroacetate, at 254 nm UV or 365 nm UV, under aerobic and anaerobic atmospheric conditions illustrated a decreased shoulder region on the curves, particularly after 365 nm UV exposure, when compared to UV irradiation applied without subsequent chemical treatment

Comparison of chromium-51 and iron-59 for estimating erythrocyte survival in the cat

International Nuclear Information System (INIS)

Liddle, C.G.; Putnam, J.P.; Berman, E.; Fisher, H.; Ostby, J.

1984-01-01

Erythrocyte survival studies were conducted on eight normal, healthy, 1-year-old male specific-pathogen-free cats using both chromium-51 and iron-59 simultaneously. The chromium-51 procedure gave a half-life value of 11.1 +/- 0.9 days. This was considerably lower than would be expected on the basis of the experimentally determined iron-59 erythrocyte survival time of 51.2 +/- 14.9 days. The results of this study indicated that there was considerable loss of the chromium-51 label in the cat other than that from senescence alone. An analysis of the chromium-51 disappearance curve indicated that there were two exponential disappearance rates for the chromium-51 label and, in the absence of cell death, approximately 67% of the label was lost with a rate constant of 0.02 per day and 33% was lost with a rate constant of 0.1 per day. An equation is presented which models the loss of chromium-51 label which could be used to calculate erythrocyte survival from a chromium-51 disappearance curve. Blood volume measurements, hemograms, bone marrow differential results, and iron kinetic values also were determined and the results presented. While a reasonable approximation of the erythrocyte life span could be made by correcting the chromium-51 values for losses other than senescence, the iron-59 procedure would be the preferred method in cats

Candida albicans survival and biofilm formation under starvation conditions.

Science.gov (United States)

Ning, Y; Hu, X; Ling, J; Du, Y; Liu, J; Liu, H; Peng, Z

2013-01-01

To investigate the survival and biofilm formation capacity of Candida albicans in starvation and under anaerobic conditions. Candida albicans growth and survival were monitored in vitro for up to 8 months. Fungal suspensions from late exponential, stationary and starvation phases were incubated on human dentine, polystyrene and glass slides. Scanning electron microscopy (SEM) was used to observe the process of biofilm formation. 2,3-bis(2-Methoxy-4-nitro-5-sulfophenyl)-2H-tetrazolium-5-carboxyanilide inner salt (XTT) reduction assay was performed to quantify the biofilm formation capability, and confocal laser scanning microscopy (CLSM) was used to study and make semi-quantitative comparisons of the ultrastructure of biofilms formed on human dentine. 'XTT bioactivity' and 'COMSTAT results' were analysed by two-way analysis of variance (ANOVA) and one-way ANOVA, respectively. Candida albicans survived for over six months. SEM demonstrated that starving C. albicans produced mature biofilms on different substrata. C. albicans of the same growth phase incubated on human dentine displayed significantly higher biofilm formation capability than on polystyrene or glass slides (P roughness coefficient and surface/volume ratio (P < 0.05). Candida albicans cells can survive and form biofilms in anaerobic and nutrient-limited conditions and may pose a treatment challenge. © 2012 International Endodontic Journal.

Peritumoral interstitial fluid flow velocity predicts survival in cervical carcinoma

International Nuclear Information System (INIS)

Hompland, Tord; Lund, Kjersti V.; Ellingsen, Christine; Kristensen, Gunnar B.; Rofstad, Einar K.

2014-01-01

Background and purpose: High tumor interstitial fluid pressure (IFP) is associated with poor outcome in locally advanced carcinoma of the uterine cervix. We have recently developed a noninvasive assay of the IFP of tumors, and in this assay, the outward interstitial fluid flow velocity at the tumor surface (v 0 ) is measured by Gd-DTPA-based DCE-MRI and used as a parameter for IFP. Here, we investigated the independent prognostic significance of v 0 in cervical cancer patients given cisplatin-based concurrent chemoradiotherapy with curative intent. Patients: The study involved 62 evaluable patients from a cohort of 74 consecutive patients (Stage IB through IIIB) with a median follow-up of 5.5 years. Results: The actuarial disease-free survival (DFS) and overall survival (OS) at 5 years were 67% and 76%, respectively. Significant associations were found between v 0 dichotomized about the median value and DFS and OS, both in the total patient cohort and a subcohort of 40 Stage IIB patients. Multivariate analysis involving stage, tumor volume, lymph node status, and v 0 revealed that only v 0 provided independent prognostic information about DFS and OS. Conclusion: This investigation demonstrates a strong, independent prognostic impact of the pretreatment peritumoral fluid flow velocity in cervical cancer

Predicting the Survival of Gastric Cancer Patients Using

Science.gov (United States)

Korhani Kangi, Azam; Bahrampour, Abbas

2018-02-26

Introduction and purpose: In recent years the use of neural networks without any premises for investigation of prognosis in analyzing survival data has increased. Artificial neural networks (ANN) use small processors with a continuous network to solve problems inspired by the human brain. Bayesian neural networks (BNN) constitute a neural-based approach to modeling and non-linearization of complex issues using special algorithms and statistical methods. Gastric cancer incidence is the first and third ranking for men and women in Iran, respectively. The aim of the present study was to assess the value of an artificial neural network and a Bayesian neural network for modeling and predicting of probability of gastric cancer patient death. Materials and Methods: In this study, we used information on 339 patients aged from 20 to 90 years old with positive gastric cancer, referred to Afzalipoor and Shahid Bahonar Hospitals in Kerman City from 2001 to 2015. The three layers perceptron neural network (ANN) and the Bayesian neural network (BNN) were used for predicting the probability of mortality using the available data. To investigate differences between the models, sensitivity, specificity, accuracy and the area under receiver operating characteristic curves (AUROCs) were generated. Results: In this study, the sensitivity and specificity of the artificial neural network and Bayesian neural network models were 0.882, 0.903 and 0.954, 0.909, respectively. Prediction accuracy and the area under curve ROC for the two models were 0.891, 0.944 and 0.935, 0.961. The age at diagnosis of gastric cancer was most important for predicting survival, followed by tumor grade, morphology, gender, smoking history, opium consumption, receiving chemotherapy, presence of metastasis, tumor stage, receiving radiotherapy, and being resident in a village. Conclusion: The findings of the present study indicated that the Bayesian neural network is preferable to an artificial neural network for

Pre-transplant levels of ficolin-3 are associated with kidney graft survival

DEFF Research Database (Denmark)

Bay, Jakob T; Hein, Estrid; Sørensen, Søren S

2013-01-01

. 97 blood donors served as controls. Ficolin-3, C4 and C3 were measured in pre-transplant as well as in control serum samples. In controls, deposition of ficolin-3, C4, C3 and the terminal complement complex (TCC) was measured in an assay based on acetylated albumin as matrix. The ficolin-3 levels...... correlated with the serum levels of C4 and C3. The serum levels of ficolin-3 correlated with the deposition of ficolin-3, C4, C3 and TCC. Survival analyses showed that high pre-transplant serum levels of ficolin-3 were associated with decreased graft survival. These results suggest an important role...

Intramacrophage survival of uropathogenic Escherichia coli: Differences between diverse clinical isolates and between mouse and human macrophages

DEFF Research Database (Denmark)

Bokil, Nilesh J.; Totsika, Makrina; Carey, Alison J.

2011-01-01

assays, CFT073 was able to survive within primary mouse bone marrow-derived macrophages (BMM) up to 24h post-infection. Three additional well-characterized clinical UPEC isolates associated with distinct UTI symptomatologies displayed variable long-term survival within BMM. UPEC strains UTI89 and VR50...... or initial uptake of bacteria. E. coli UTI89 localized to a Lamp1+ vesicular compartment within BMM. In contrast to survival within mouse BMM, intracellular bacterial loads of VR50 were low in both human monocyte-derived macrophages (HMDM) and in human T24 bladder epithelial cells. Collectively, these data...

Novel alternative to antibiotics in shrimp hatchery: effects of the essential oil of Cinnamosma fragrans on survival and bacterial concentration of Penaeus monodon larvae.

Science.gov (United States)

Randrianarivelo, R; Danthu, P; Benoit, C; Ruez, P; Raherimandimby, M; Sarter, S

2010-08-01

The activity of two essential oils (EOs) of Cinnamosma fragrans, an endemic plant to Madagascar (B8: linalool-type and B143: 1,8-cineole-type), against bacterial isolates from a shrimp hatchery of Penaeus monodon and their effects on the survival and bacterial concentration of larvae were determined. Minimum inhibitory concentrations were determined using a broth dilution technique. The bacterial concentrations of both larvae and water tank were assessed on Marine agar and Thiosulfate Citrate Bile Sucrose agar. The assays took place in OSO Farming's shrimp hatchery in Madagascar. EOs were directly added to the water tank. Regarding the survival, the assays in larval culture (four replicates each of B8, B143, E and control) showed that B8 oil had a similar effect (P > 0.05) as the antibiotic (Erythromycin) and was more active than B143 (P larvae for all assays. Both C. fragrans essential oils, as antibiotic, exhibited significantly higher survival rates and lower bacterial concentrations of the larvae than the control (oil and antibiotic free). The potential of C. fragrans essential oil to control the bacterial load in in vivo conditions, thereby enhancing survival rate of P. monodon larvae, makes it a relevant option for developing a novel alternative to antibiotics in shrimp hatchery culture.

Acetohydroxyacid synthase (AHAS) in vivo assay for screening imidazolinone-resistance in sunflower (Helianthus annuus L.).

Science.gov (United States)

Vega, T; Breccia, G; Gil, M; Zorzoli, R; Picardi, L; Nestares, G

2012-12-01

The objective of this work was to evaluate the in vivo acetohydroxyacid synthase (AHAS) activity response to imidazolinones and its possible use as a selection method for evaluating AHAS inhibitor resistance. In vivo AHAS assay and the comparison of parameters from dose-response curves have been used as a valid tool for comparing sunflower lines and hybrids differing in imidazolinone resistance. The sunflower resistant genotypes evaluated here were 100-fold and 20-fold more resistant compared with the susceptible line for imazethapyr and imazapyr, respectively. This assay also allowed discrimination of homozygous from heterozygous genotypes for I(mr1) locus that codify for the catalytic subunit of AHAS. The in vivo AHAS assay described in this study was useful for the selection of sunflower genotypes differing in herbicide resistance and could be a useful tool when breeding for imidazolinone resistance in sunflower. Copyright © 2012 Elsevier Masson SAS. All rights reserved.

WE-H-BRA-08: A Monte Carlo Cell Nucleus Model for Assessing Cell Survival Probability Based On Particle Track Structure Analysis

Energy Technology Data Exchange (ETDEWEB)

Lee, B [Northwestern Memorial Hospital, Chicago, IL (United States); Georgia Institute of Technology, Atlanta, GA (Georgia); Wang, C [Georgia Institute of Technology, Atlanta, GA (Georgia)

2016-06-15

Purpose: To correlate the damage produced by particles of different types and qualities to cell survival on the basis of nanodosimetric analysis and advanced DNA structures in the cell nucleus. Methods: A Monte Carlo code was developed to simulate subnuclear DNA chromatin fibers (CFs) of 30nm utilizing a mean-free-path approach common to radiation transport. The cell nucleus was modeled as a spherical region containing 6000 chromatin-dense domains (CDs) of 400nm diameter, with additional CFs modeled in a sparser interchromatin region. The Geant4-DNA code was utilized to produce a particle track database representing various particles at different energies and dose quantities. These tracks were used to stochastically position the DNA structures based on their mean free path to interaction with CFs. Excitation and ionization events intersecting CFs were analyzed using the DBSCAN clustering algorithm for assessment of the likelihood of producing DSBs. Simulated DSBs were then assessed based on their proximity to one another for a probability of inducing cell death. Results: Variations in energy deposition to chromatin fibers match expectations based on differences in particle track structure. The quality of damage to CFs based on different particle types indicate more severe damage by high-LET radiation than low-LET radiation of identical particles. In addition, the model indicates more severe damage by protons than of alpha particles of same LET, which is consistent with differences in their track structure. Cell survival curves have been produced showing the L-Q behavior of sparsely ionizing radiation. Conclusion: Initial results indicate the feasibility of producing cell survival curves based on the Monte Carlo cell nucleus method. Accurate correlation between simulated DNA damage to cell survival on the basis of nanodosimetric analysis can provide insight into the biological responses to various radiation types. Current efforts are directed at producing cell

Rapid screening assay for calcium bioavailability studies

International Nuclear Information System (INIS)

Luhrsen, K.R.; Hudepohl, G.R.; Smith, K.T.

1986-01-01

Calcium bioavailability has been studied by numerous techniques. The authors report here the use of the gamma emitting isotope of calcium ( 47 Ca) in a whole body retention assay system. In this system, calcium sources are administered by oral gavage and subsequent counts are determined and corrected for isotopic decay. Unlike iron and zinc retention curves, which exhibit a 2-3 day equilibration period, calcium reaches equilibration after 24 hours. Autoradiographic analysis of the femurs indicate that the newly absorbed calcium is rapidly distributed to the skeletal system. Moreover, the isotope is distributed along the entire bone. Comparisons of calcium bioavailability were made using intrinsic/extrinsic labeled milk from two species i.e. rat and goat as well as CaCO 3 . In addition, extrinsic labeled cow milk was examined. In the rat, the extrinsic labeled calcium from milk was better absorbed than the intrinsic calcium. This was not the case in goat milk or the calcium carbonate which exhibited no significant differences. Chromatographic analysis of the labeled milk indicates a difference in distribution of the 47 Ca. From these data, the authors recommend the use of this assay system in calcium bioavailability studies. The labeling studies and comparisons indicate caution should be used, however, in labeling techniques and species milk comparison

The curve shortening problem

CERN Document Server

Chou, Kai-Seng

2001-01-01

Although research in curve shortening flow has been very active for nearly 20 years, the results of those efforts have remained scattered throughout the literature. For the first time, The Curve Shortening Problem collects and illuminates those results in a comprehensive, rigorous, and self-contained account of the fundamental results.The authors present a complete treatment of the Gage-Hamilton theorem, a clear, detailed exposition of Grayson''s convexity theorem, a systematic discussion of invariant solutions, applications to the existence of simple closed geodesics on a surface, and a new, almost convexity theorem for the generalized curve shortening problem.Many questions regarding curve shortening remain outstanding. With its careful exposition and complete guide to the literature, The Curve Shortening Problem provides not only an outstanding starting point for graduate students and new investigations, but a superb reference that presents intriguing new results for those already active in the field.

Characterization of radiation-induced Apoptosis in rodent cell lines

International Nuclear Information System (INIS)

Guo, Min; Chen, Changhu; Ling, C.C.

1997-01-01

For REC:myc(ch1), Rat1 and Rat1:myc b cells, we determined the events in the development of radiation-induced apoptosis to be in the following order: cell division followed by chromatin condensation, membrane blebbing, loss of adhesion and the uptake of vital dye. Experimental data which were obtained using 4 He ions of well defined energies and which compared the dependence of apoptosis and clonogenic survival on 4 He range strongly suggested that in our cells both apoptosis and loss of clonogenic survival resulted from radiation damage to the cell nucleus. Corroboratory evidence was that BrdU incorporation sensitized these cells to radiation-induced apoptosis. Comparing the dose response for apoptosis and the clonogenic survival curves for Rat1 and Rat1:myc b cells, we concluded that radiation-induced cell inactivation as assayed by clonogenic survival, and that a modified linear-quadratic model, proposed previously, modeled such a contribution effectively. In the same context, the selective increase in radiation-induced apoptosis. Comparing the dose response for apoptosis and the clonogenic survival curves for Rat1 and Rat1:myc b cells, we concluded that radiation-induced apoptosis contributed to the overall radiation-induced cell inactivation as assayed by clonogenic survival, and that a modified linear-quadratic model, proposed previously, modeled such a contribution effectively. In the same context, the selective increase in radiation-induced apoptosis during late S and G 2 phases reduced the relative radioresistance observed for clonogenic survival during late S and G 2 phases. 30 refs., 8 figs

Analysis of Chemopredictive Assay for Targeting Cancer Stem Cells in Glioblastoma Patients

Directory of Open Access Journals (Sweden)

Candace M. Howard

2017-04-01

Full Text Available Introduction: The prognosis of glioblastoma (GBM treated with standard-of-care maximal surgical resection and concurrent adjuvant temozolomide (TMZ/radiotherapy remains very poor (less than 15 months. GBMs have been found to contain a small population of cancer stem cells (CSCs that contribute to tumor propagation, maintenance, and treatment resistance. The highly invasive nature of high-grade gliomas and their inherent resistance to therapy lead to very high rates of recurrence. For these reasons, not all patients with similar diagnoses respond to the same chemotherapy, schedule, or dose. Administration of ineffective anticancer therapy is not only costly but more importantly burdens the patient with unnecessary toxicity and selects for the development of resistant cancer cell clones. We have developed a drug response assay (ChemoID that identifies the most effective chemotherapy against CSCs and bulk of tumor cells from of a panel of potential treatments, offering great promise for individualized cancer management. Providing the treating physician with drug response information on a panel of approved drugs will aid in personalized therapy selections of the most effective chemotherapy for individual patients, thereby improving outcomes. A prospective study was conducted evaluating the use of the ChemoID drug response assay in GBM patients treated with standard of care. Methods: Forty-one GBM patients (mean age 54 years, 59% male, all eligible for a surgical biopsy, were enrolled in an Institutional Review Board–approved protocol, and fresh tissue samples were collected for drug sensitivity testing. Patients were all treated with standard-of-care TMZ plus radiation with or without maximal surgery, depending on the status of the disease. Patients were prospectively monitored for tumor response, time to recurrence, progression-free survival (PFS, and overall survival (OS. Odds ratio (OR associations of 12-month recurrence, PFS, and OS outcomes

Modeling time-to-event (survival) data using classification tree analysis.

Science.gov (United States)

Linden, Ariel; Yarnold, Paul R

2017-12-01

Time to the occurrence of an event is often studied in health research. Survival analysis differs from other designs in that follow-up times for individuals who do not experience the event by the end of the study (called censored) are accounted for in the analysis. Cox regression is the standard method for analysing censored data, but the assumptions required of these models are easily violated. In this paper, we introduce classification tree analysis (CTA) as a flexible alternative for modelling censored data. Classification tree analysis is a "decision-tree"-like classification model that provides parsimonious, transparent (ie, easy to visually display and interpret) decision rules that maximize predictive accuracy, derives exact P values via permutation tests, and evaluates model cross-generalizability. Using empirical data, we identify all statistically valid, reproducible, longitudinally consistent, and cross-generalizable CTA survival models and then compare their predictive accuracy to estimates derived via Cox regression and an unadjusted naïve model. Model performance is assessed using integrated Brier scores and a comparison between estimated survival curves. The Cox regression model best predicts average incidence of the outcome over time, whereas CTA survival models best predict either relatively high, or low, incidence of the outcome over time. Classification tree analysis survival models offer many advantages over Cox regression, such as explicit maximization of predictive accuracy, parsimony, statistical robustness, and transparency. Therefore, researchers interested in accurate prognoses and clear decision rules should consider developing models using the CTA-survival framework. © 2017 John Wiley & Sons, Ltd.

Experimental platform utilising melting curve technology for detection of mutations in Mycobacterium tuberculosis isolates.

Science.gov (United States)

Broda, Agnieszka; Nikolayevskyy, Vlad; Casali, Nicki; Khan, Huma; Bowker, Richard; Blackwell, Gemma; Patel, Bhakti; Hume, James; Hussain, Waqar; Drobniewski, Francis

2018-04-20

Tuberculosis (TB) remains one of the most deadly infections with approximately a quarter of cases not being identified and/or treated mainly due to a lack of resources. Rapid detection of TB or drug-resistant TB enables timely adequate treatment and is a cornerstone of effective TB management. We evaluated the analytical performance of a single-tube assay for multidrug-resistant TB (MDR-TB) on an experimental platform utilising RT-PCR and melting curve analysis that could potentially be operated as a point-of-care (PoC) test in resource-constrained settings with a high burden of TB. Firstly, we developed and evaluated the prototype MDR-TB assay using specimens extracted from well-characterised TB isolates with a variety of distinct rifampicin and isoniazid resistance conferring mutations and nontuberculous Mycobacteria (NTM) strains. Secondly, we validated the experimental platform using 98 clinical sputum samples from pulmonary TB patients collected in high MDR-TB settings. The sensitivity of the platform for TB detection in clinical specimens was 75% for smear-negative and 92.6% for smear-positive sputum samples. The sensitivity of detection for rifampicin and isoniazid resistance was 88.9 and 96.0% and specificity was 87.5 and 100%, respectively. Observed limitations in sensitivity and specificity could be resolved by adjusting the sample preparation methodology and melting curve recognition algorithm. Overall technology could be considered a promising PoC methodology especially in resource-constrained settings based on its combined accuracy, convenience, simplicity, speed, and cost characteristics.

Response of cultured normal human mammary epithelial cells to X rays

International Nuclear Information System (INIS)

Yang, T.C.; Stampfer, M.R.; Smith, H.S.

1983-01-01

The effect of X rays on the reproductive death of cultured normal human mammary epithelial cells was examined. Techniques were developed for isolating and culturing normal human mammary epithelial cells which provide sufficient cells at second passage for radiation studies, and an efficient clonogenic assay suitable for measuring radiation survival curves. It was found that the survival curves for epithelial cells from normal breast tissue were exponential and had D 0 values of about 109-148 rad for 225 kVp X rays. No consistent change in cell radiosensitivity with the age of donor was observed, and no sublethal damage repair in these cells could be detected with the split-dose technique

Intratumoral heterogeneity of 18F-FDG uptake predicts survival in patients with pancreatic ductal adenocarcinoma

International Nuclear Information System (INIS)

Hyun, Seung Hyup; Kim, Ho Seong; Lee, Kyung-Han; Kim, Byung-Tae; Choi, Joon Young; Choi, Seong Ho; Choi, Dong Wook; Lee, Jong Kyun; Lee, Kwang Hyuck; Park, Joon Oh

2016-01-01

To assess whether intratumoral heterogeneity measured by 18 F-FDG PET texture analysis has potential as a prognostic imaging biomarker in patients with pancreatic ductal adenocarcinoma (PDAC). We evaluated a cohort of 137 patients with newly diagnosed PDAC who underwent pretreatment 18 F-FDG PET/CT from January 2008 to December 2010. First-order (histogram indices) and higher-order (grey-level run length, difference, size zone matrices) textural features of primary tumours were extracted by PET texture analysis. Conventional PET parameters including metabolic tumour volume (MTV), total lesion glycolysis (TLG), and standardized uptake value (SUV) were also measured. To assess and compare the predictive performance of imaging biomarkers, time-dependent receiver operating characteristic (ROC) curves for censored survival data and areas under the ROC curve (AUC) at 2 years after diagnosis were used. Associations between imaging biomarkers and overall survival were assessed using Cox proportional hazards regression models. The best imaging biomarker for overall survival prediction was first-order entropy (AUC = 0.720), followed by TLG (AUC = 0.697), MTV (AUC = 0.692), and maximum SUV (AUC = 0.625). After adjusting for age, sex, clinical stage, tumour size and serum CA19-9 level, multivariable Cox analysis demonstrated that higher entropy (hazard ratio, HR, 5.59; P = 0.028) was independently associated with worse survival, whereas TLG (HR 0.98; P = 0.875) was not an independent prognostic factor. Intratumoral heterogeneity of 18 F-FDG uptake measured by PET texture analysis is an independent predictor of survival along with tumour stage and serum CA19-9 level in patients with PDAC. In addition, first-order entropy as a measure of intratumoral metabolic heterogeneity is a better quantitative imaging biomarker of prognosis than conventional PET parameters. (orig.)

Converging or Crossing Curves: Untie the Gordian Knot or Cut it? Appropriate Statistics for Non-Proportional Hazards in Decitabine DACO-016 Study (AML).

Science.gov (United States)

Tomeczkowski, Jörg; Lange, Ansgar; Güntert, Andreas; Thilakarathne, Pushpike; Diels, Joris; Xiu, Liang; De Porre, Peter; Tapprich, Christoph

2015-09-01

Among patients with acute myeloid leukemia (AML), the DACO-016 randomized study showed reduction in mortality for decitabine [Dacogen(®) (DAC), Eisai Inc., Woodcliff Lake, NJ, USA] compared with treatment choice (TC): at primary analysis the hazard ratio (HR) was 0.85 (95% confidence interval 0.69-1.04; stratified log-rank P = 0.108). With two interim analyses, two-sided alpha was adjusted to 0.0462. With 1-year additional follow-up the HR reached 0.82 (nominal P = 0.0373). These data resulted in approval of DAC in the European Union, though not in the United States. Though pre-specified, the log-rank test could be considered not optimal to assess the observed survival difference because of the non-proportional hazard nature of the survival curves. We applied the Wilcoxon test as a sensitivity analysis. Patients were randomized to DAC (N = 242) or TC (N = 243). One-hundred and eight (44.4%) patients in the TC arm and 91 (37.6%) patients in the DAC arm selectively crossed over to subsequent disease modifying therapies at progression, which might impact the survival beyond the median with resultant converging curves (and disproportional hazards). The stratified Wilcoxon test showed a significant improvement in median (CI 95%) overall survival with DAC [7.7 (6.2; 9.2) months] versus TC [5.0 (4.3; 6.3) months; P = 0.0458]. Wilcoxon test indicated significant increase in survival for DAC versus TC compared to log-rank test. Janssen-Cilag GmbH.

Cougar survival and source-sink structure on Greater Yellowstone's Northern Range

Science.gov (United States)

Ruth, T.K.; Haroldson, M.A.; Murphy, K.M.; Buotte, P.C.; Hornocker, M.G.; Quigley, H.B.

2011-01-01

We studied survival and causes of mortality of radiocollared cougars (Puma concolor) on the Greater Yellowstone Northern Range (GYNR) prior to (1987–1994) and after wolf (Canis lupus) reintroduction (1998–2005) and evaluated temporal, spatial, and environmental factors that explain variation in adult, subadult, and kitten survival. Using Program MARK and multimodel inference, we modeled cougar survival based on demographic status, season, and landscape attributes. Our best models for adult and independent subadults indicated that females survived better than males and survival increased with age until cougars reached older ages. Lower elevations and increasing density of roads, particularly in areas open to cougar hunting north of Yellowstone National Park (YNP), increased mortality risks for cougars on the GYNR. Indices of ungulate biomass, cougar and wolf population size, winter severity, rainfall, and individual characteristics such as the presence of dependent young, age class, and use of Park or Wilderness were not important predictors of survival. Kitten survival increased with age, was lower during winter, increased with increasing minimum estimates of elk calf biomass, and increased with increasing density of adult male cougars. Using our best model, we mapped adult cougar survival on the GYNR landscape. Results of receiver operating characteristic (ROC) analysis indicated a good model fit for both female (area under the curve [AUC] = 0.81, 95%CI = 0.70–0.92, n = 35 locations) and male cougars (AUC = 0.84, 95%CI = 0.74–0.94, n = 49 locations) relative to hunter harvest locations in our study area. Using minimum estimates of survival necessary to sustain the study population, we developed a source-sink surface and we identify several measures that resource management agencies can take to enhance cougar population management based on a source-sink strategy.

Part 5: Receiver Operating Characteristic Curve and Area under the Curve

Directory of Open Access Journals (Sweden)

Saeed Safari

2016-04-01

Full Text Available Multiple diagnostic tools are used by emergency physicians,every day. In addition, new tools are evaluated to obtainmore accurate methods and reduce time or cost of conventionalones. In the previous parts of this educationalseries, we described diagnostic performance characteristicsof diagnostic tests including sensitivity, specificity, positiveand negative predictive values, and likelihood ratios. Thereceiver operating characteristics (ROC curve is a graphicalpresentation of screening characteristics. ROC curve is usedto determine the best cutoff point and compare two or moretests or observers by measuring the area under the curve(AUC. In this part of our educational series, we explain ROCcurve and two methods to determine the best cutoff value.

A nomogram for predicting survival in patients with breast cancer brain metastasis.

Science.gov (United States)

Huang, Zhou; Sun, Bing; Wu, Shikai; Meng, Xiangying; Cong, Yang; Shen, Ge; Song, Santai

2018-05-01

Brain metastasis (BM) is common in patients with breast cancer. Predicting patient survival is critical for the clinical management of breast cancer brain metastasis (BCBM). The present study was designed to develop and evaluate a prognostic model for patients with newly diagnosed BCBM. Based on the clinical data of patients with BCBM treated in the Affiliated Hospital of Academy of Military Medical Sciences (Beijing, China) between 2002 and 2014, a nomogram was developed to predict survival using proportional hazards regression analysis. The model was validated internally by bootstrapping, and the concordance index (c-index) was calculated. A calibration curve and c-index were used to evaluate discriminatory and predictive ability, in order to compare the nomogram with widely used models, including recursive partitioning analysis (RPA), graded prognostic assessment (GPA) and breast-graded prognostic assessment (Breast-GPA). A total of 411 patients with BCBM were included in the development of this predictive model. The median overall survival time was 14.1 months. Statistically significant predictors for patient survival included biological subtype, Karnofsky performance score, leptomeningeal metastasis, extracranial metastasis, the number of brain metastases and disease-free survival. A nomogram for predicting 1- and 2-year overall survival rates was constructed, which exhibited good accuracy in predicting overall survival with a concordance index of 0.735. This model outperformed RPA, GPA and Breast-GPA, based on the comparisons of the c-indexes. The nomogram constructed based on a multiple factor analysis was able to more accurately predict the individual survival probability of patients with BCBM, compared with existing models.

The prognostic value of the suPARnosticTM ELISA assay in HIV-1 infected individuals is not affected by uPAR promoter polymorphisms

DEFF Research Database (Denmark)

Schneider, Uffe; Nielsen, Rikke; Pedersen, Court

2007-01-01

. METHODS: DNA samples were collected retrospectively from 145 Danes infected with HIV-1 with known seroconversion times. In addition, plasma was collected retrospectively from 81 of these participants for use in the suPAR analysis. Survival was analysed using Kaplan Meier analysis. RESULTS: Survival...... to A transition at -118 and an A to G transition at -465 comparative to the transcription start site. These promoter transitions did not influence neither the suPAR levels nor patient survival. CONCLUSION: Plasma suPAR levels, as measured by the suPARnosticTM assay, were strongly predictive of survival in ART...

A Data Analysis Pipeline Accounting for Artifacts in Tox21 Quantitative High-Throughput Screening Assays.

Science.gov (United States)

Hsieh, Jui-Hua; Sedykh, Alexander; Huang, Ruili; Xia, Menghang; Tice, Raymond R

2015-08-01

A main goal of the U.S. Tox21 program is to profile a 10K-compound library for activity against a panel of stress-related and nuclear receptor signaling pathway assays using a quantitative high-throughput screening (qHTS) approach. However, assay artifacts, including nonreproducible signals and assay interference (e.g., autofluorescence), complicate compound activity interpretation. To address these issues, we have developed a data analysis pipeline that includes an updated signal noise-filtering/curation protocol and an assay interference flagging system. To better characterize various types of signals, we adopted a weighted version of the area under the curve (wAUC) to quantify the amount of activity across the tested concentration range in combination with the assay-dependent point-of-departure (POD) concentration. Based on the 32 Tox21 qHTS assays analyzed, we demonstrate that signal profiling using wAUC affords the best reproducibility (Pearson's r = 0.91) in comparison with the POD (0.82) only or the AC(50) (i.e., half-maximal activity concentration, 0.81). Among the activity artifacts characterized, cytotoxicity is the major confounding factor; on average, about 8% of Tox21 compounds are affected, whereas autofluorescence affects less than 0.5%. To facilitate data evaluation, we implemented two graphical user interface applications, allowing users to rapidly evaluate the in vitro activity of Tox21 compounds. © 2015 Society for Laboratory Automation and Screening.

Nivolumab versus Cabozantinib: Comparing Overall Survival in Metastatic Renal Cell Carcinoma.

Directory of Open Access Journals (Sweden)

Witold Wiecek

Full Text Available Renal-cell carcinoma (RCC affects over 330,000 new patients every year, of whom 1/3 present with metastatic RCC (mRCC at diagnosis. Most mRCC patients treated with a first-line agent relapse within 1 year and need second-line therapy. The present study aims to compare overall survival (OS between nivolumab and cabozantinib from two recent pivotal studies comparing, respectively, each one of the two emerging treatments against everolimus in patients who relapse following first-line treatment. Comparison is traditionally carried out using the Bucher method, which assumes proportional hazard. Since OS curves intersected in one of the pivotal studies, models not assuming proportional hazards were also considered to refine the comparison. Four Bayesian parametric survival network meta-analysis models were implemented on overall survival (OS data digitized from the Kaplan-Meier curves reported in the studies. Three models allowing hazard ratios (HR to vary over time were assessed against a fixed-HR model. The Bucher method favored cabozantinib, with a fixed HR for OS vs. nivolumab of 1.09 (95% confidence interval: [0.77, 1.54]. However, all models with time-varying HR showed better fits than the fixed-HR model. The log-logistic model fitted the data best, exhibiting a HR for OS initially favoring cabozantinib, the trend inverting to favor nivolumab after month 5 (95% credible interval <1 from 10 months. The initial probability of cabozantinib conferring superior OS was 54%, falling to 41.5% by month 24. Numerical differences in study-adjusted OS estimates between the two treatments remained small. This study evidences that HR for OS of nivolumab vs. cabozantinib varies over time, favoring cabozantinib in the first months of treatment but nivolumab afterwards, a possible indication that patients with poor prognosis benefit more from cabozantinib in terms of survival, nivolumab benefiting patients with better prognosis. More evidence, including real

Signature Curves Statistics of DNA Supercoils

OpenAIRE

Shakiban, Cheri; Lloyd, Peter

2004-01-01

In this paper we describe the Euclidean signature curves for two dimensional closed curves in the plane and their generalization to closed space curves. The focus will be on discrete numerical methods for approximating such curves. Further we will apply these numerical methods to plot the signature curves related to three-dimensional simulated DNA supercoils. Our primary focus will be on statistical analysis of the data generated for the signature curves of the supercoils. We will try to esta...

Method of construction spatial transition curve

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S.V. Didanov

2013-04-01

Full Text Available Purpose. The movement of rail transport (speed rolling stock, traffic safety, etc. is largely dependent on the quality of the track. In this case, a special role is the transition curve, which ensures smooth insertion of the transition from linear to circular section of road. The article deals with modeling of spatial transition curve based on the parabolic distribution of the curvature and torsion. This is a continuation of research conducted by the authors regarding the spatial modeling of curved contours. Methodology. Construction of the spatial transition curve is numerical methods for solving nonlinear integral equations, where the initial data are taken coordinate the starting and ending points of the curve of the future, and the inclination of the tangent and the deviation of the curve from the tangent plane at these points. System solutions for the numerical method are the partial derivatives of the equations of the unknown parameters of the law of change of torsion and length of the transition curve. Findings. The parametric equations of the spatial transition curve are calculated by finding the unknown coefficients of the parabolic distribution of the curvature and torsion, as well as the spatial length of the transition curve. Originality. A method for constructing the spatial transition curve is devised, and based on this software geometric modeling spatial transition curves of railway track with specified deviations of the curve from the tangent plane. Practical value. The resulting curve can be applied in any sector of the economy, where it is necessary to ensure a smooth transition from linear to circular section of the curved space bypass. An example is the transition curve in the construction of the railway line, road, pipe, profile, flat section of the working blades of the turbine and compressor, the ship, plane, car, etc.

Mutagenicity of irradiated food in the host mediated assay system

International Nuclear Information System (INIS)

Johnston-Arthur, T.; Turanitz, K.; Hruby, R.; Stehlik, G.; Brena-Valle, M.

1975-01-01

Groups of Swiss albino mice (SPF) fed with normal and gamma-irradiated food at doses of 0.75, 1.5 and 3.0 Mrad, were injected intraperitoneally with SALMONELLA TYPHIMURIUM TA 1530 for the host mediated assay test of mutagenesis. The mutation frequency was calculated in terms of the number of mutant colonies per unit number of surviving cells. The results indicate that there is a significant increase in mutation frequency induced by the 3 Mrad sterilized food. No difference was observed in the 0.75 Mrad dose when compared with the control

Comparison of colorectal and gastric cancer: Survival and prognostic factors

International Nuclear Information System (INIS)

Moghimi-Dehkordi, Bijan; Safaee, Azadeh; Zali, Mohammad R

2009-01-01

Gastric and colorectal cancers are the most common gastrointestinal malignancies in Iran. We aim to compare the survival rates and prognostic factors between these two cancers. We studied 1873 patients with either gastric or colorectal cancer who were registered in one referral cancer registry center in Tehran, Iran. All patients were followed from their time of diagnosis until December 2006 (as failure time). Survival curves were calculated according to the Kaplan-Meier Method and compared by the Log-rank test. Multivariate analysis of prognostic factors was carried out using the Cox proportional hazard model. Of 1873 patients, there were 746 with gastric cancer and 1138 with colorectal cancer. According to the Kaplan-Meier method 1, 3, 5, and 7-year survival rates were 71.2, 37.8, 25.3, and 19.5%, respectively, in gastric cancer patients and 91.1, 73.1, 61, and 54.9%, respectively, in patients with colorectal cancer. Also, univariate analysis showed that age at diagnosis, sex, grade of tumor, and distant metastasis were of prognostic significance in both cancers ( P < 0.0001). However, in multivariate analysis, only distant metastasis in colorectal cancer and age at diagnosis, grade of tumor, and distant metastasis in colorectal cancer were identified as independent prognostic factors influencing survival. According to our findings, survival is significantly related to histological differentiation of tumor and distant metastasis in colorectal cancer patients and only to distant metastasis in gastric cancer patients. (author)

Tanacetum parthenium leaf extract mediated survival protection in lethally irradiated Swiss albino mice

International Nuclear Information System (INIS)

Shetty, Prashanth; Pooja, S.; Suchetha Kumari, N.; Shetty, Jayaram; Peter, Alex John; Jose, Jerish M.

2016-01-01

Search for less-toxic radioprotectors has spurred interest in the development of natural products. In Ayurveda, the traditional medicine, Tanacetum species have been used to treat ailments since ancient times throughout the world. Effects of the administration of different concentrations of Tanacetum parthenium leaf aqueous extract (TPLA), Tanacetum parthenium leaf ethanolic extract (TPLE) were investigated in Swiss albino mice. Mice (20-25 g) were randomly divided into 8 groups of ten animals each. The control group and the radiation group were treated daily with oral administration of saline for 15 days. Each subgroups of TPLA and TPLE were treated with doses of 50, 100 and 250 mg/kg daily for 15 days. On the 15th day, all were irradiated with 10 Gy whole body irradiation. Survival was observed daily up to 30th post-irradiation day. Data were analysed using the Kaplan-Meier survival curves. The significance difference in survival between control, radiation and treatment groups were observed (P < 0.001). Current studies revealed the protective effect of Tanacetum parthenium rendering high survivability in lethally irradiated mice. (author)

Photoelectic BV Light Curves of Algol and the Interpretations of the Light Curves

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Ho-Il Kim

1985-06-01

Full Text Available Standardized B and V photoelectric light curves of Algol are made with the observations obtained during 1982-84 with the 40-cm and the 61-cm reflectors of Yonsei University Observatory. These light curves show asymmetry between ascending and descending shoulders. The ascending shoulder is 0.02 mag brighter than descending shoulder in V light curve and 0.03 mag in B light curve. These asymmetric light curves are interpreted as the result of inhomogeneous energy distribution on the surface of one star of the eclipsing pair rather than the result of gaseous stream flowing from KOIV to B8V star. The 180-year periodicity, so called great inequality, are most likely the result proposed by Kim et al. (1983 that the abrupt and discrete mass losses of cooler component may be the cause of this orbital change. The amount of mass loss deduced from these discrete period changes turned out to be of the order of 10^(-6 - 10^(-5 Msolar.

Quantitative detection and typing of hepatitis D virus in human serum by real-time polymerase chain reaction and melting curve analysis.

Science.gov (United States)

Hofmann, Joerg; Frenzel, Katrin; Minh, Bui Q; von Haeseler, Arndt; Edelmann, Anke; Ross, Stefan R; Berg, Thomas; Krüger, Detlev H; Meisel, Helga

2010-06-01

Hepatitis D virus (HDV) infection is an important etiologic agent of fulminant hepatitis and may aggravate the clinical course of chronic hepatitis B infection resulting in cirrhosis and liver failure. This report describes the establishment of a real-time reverse transcriptase polymerase chain reaction method that allows the quantitative detection of HDV-1 and HDV-3 with a sensitivity in a linear range of 2 x 10(3) to 10(8) copies/mL. Additionally, the new assay provides the opportunity to distinguish HDV-1 from HDV-3 by a subsequent melting curve analysis, an important option because these HDV types are highly associated with severe clinical outcome. The results of the melting curve analysis of 42 HDV sequences obtained in this study and the phylogenetic analysis based on 139 full-length sequences from GenBank were consistent and showed that all sequences described here cluster within the HDV-1 clade. Therefore, this assay is useful for monitoring of antiviral treatment and molecular epidemiologic studies of HDV distribution. Copyright 2010 Elsevier Inc. All rights reserved.

Validation of an immunodiagnostic assay for detection of 13 Streptococcus pneumoniae serotype-specific polysaccharides in human urine.

Science.gov (United States)

Pride, Michael W; Huijts, Susanne M; Wu, Kangjian; Souza, Victor; Passador, Sherry; Tinder, Chunyan; Song, Esther; Elfassy, Arik; McNeil, Lisa; Menton, Ronald; French, Roger; Callahan, Janice; Webber, Chris; Gruber, William C; Bonten, Marc J M; Jansen, Kathrin U

2012-08-01

To improve the clinical diagnosis of pneumococcal infection in bacteremic and nonbacteremic community-acquired pneumonia (CAP), a Luminex technology-based multiplex urinary antigen detection (UAD) diagnostic assay was developed and validated. The UAD assay can simultaneously detect 13 different serotypes of Streptococcus pneumoniae by capturing serotype-specific S. pneumoniae polysaccharides (PnPSs) secreted in human urine. Assay specificity is achieved by capturing the polysaccharides with serotype-specific monoclonal antibodies (MAbs) on spectrally unique microspheres. Positivity for each serotype was based on positivity cutoff values calculated from a standard curve run on each assay plate together with positive- and negative-control urine samples. The assay is highly specific, since significant signals are detected only when each PnPS was paired with its homologous MAb-coated microspheres. Validation experiments demonstrated excellent accuracy and precision. The UAD assay and corresponding positivity cutoff values were clinically validated by assessing 776 urine specimens obtained from patients with X-ray-confirmed CAP. The UAD assay demonstrated 97% sensitivity and 100% specificity using samples obtained from patients with bacteremic, blood culture-positive CAP. Importantly, the UAD assay identified Streptococcus pneumoniae (13 serotypes) in a proportion of individuals with nonbacteremic CAP, a patient population for which the pneumococcal etiology of CAP was previously difficult to assess. Therefore, the UAD assay provides a specific, noninvasive, sensitive, and reproducible tool to support vaccine efficacy as well as epidemiological evaluation of pneumococcal disease, including CAP, in adults.

A Journey Between Two Curves

Directory of Open Access Journals (Sweden)

Sergey A. Cherkis

2007-03-01

Full Text Available A typical solution of an integrable system is described in terms of a holomorphic curve and a line bundle over it. The curve provides the action variables while the time evolution is a linear flow on the curve's Jacobian. Even though the system of Nahm equations is closely related to the Hitchin system, the curves appearing in these two cases have very different nature. The former can be described in terms of some classical scattering problem while the latter provides a solution to some Seiberg-Witten gauge theory. This note identifies the setup in which one can formulate the question of relating the two curves.

Dose rate effects on survival of two insect species which commonly infest stored corn

International Nuclear Information System (INIS)

Adem, E.; Uribe, R.M.; Watters, F.L.

1979-01-01

A study of the dose rate effects on survival of two species of insects which commonly infest commercial maize in Mexico was undertaken using 60 Co γ radiation and 1.0 MeV electrons, to determine whether an optimum dose rate exists for the irradiation of grain infested with these insects. Experiments have shown that the effectiveness of γ and electron irradiation were not influenced by dose rates from 10 to 120 Gy/min for 60 Co and 35 to 300 Gy/min for electrons when the insects were irradiated at 2500 Gy. Survival curves for each species are presented for both types of radiation. (author)

Radiation sensitivity of human lung cancer cell lines

International Nuclear Information System (INIS)

Carmichael, J.; Degraff, W.G.; Gamson, J.; Russo, G.; Mitchell, J.B.; Gazdar, A.F.; Minna, J.D.; Levitt, M.L.

1989-01-01

X-Ray survival curves were determined using a panel of 17 human lung cancer cell lines, with emphasis on non-small cell lung cancer (NSCLC). In contrast to classic small cell lung cancer (SCLC) cell lines, NSCLC cell lines were generally less sensitive to radiation as evidenced by higher radiation survival curve extrapolation numbers, surviving fraction values following a 2Gy dose (SF2) and the mean inactivation dose values (D) values. The spectrum of in vitro radiation responses observed was similar to that expected in clinical practice, although mesothelioma was unexpectedly sensitive in vitro. Differences in radiosensitivity were best distinguished by comparison of SF2 values. Some NSCLC lines were relatively sensitive, and in view of this demonstrable variability in radiation sensitivity, the SF2 value may be useful for in vitro predictive assay testing of clinical specimens. (author)

Protein Analytical Assays for Diagnosing, Monitoring, and Choosing Treatment for Cancer Patients

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Alicia D. Powers

2012-01-01

Full Text Available Cancer treatment is often hindered by inadequate methods for diagnosing the disease or insufficient predictive capacity regarding therapeutic efficacy. Targeted cancer treatments, including Bcr-Abl and EGFR kinase inhibitors, have increased survival for some cancer patients but are ineffective in other patients. In addition, many patients who initially respond to targeted inhibitor therapy develop resistance during the course of treatment. Molecular analysis of cancer cells has emerged as a means to tailor treatment to particular patients. While DNA analysis can provide important diagnostic information, protein analysis is particularly valuable because proteins are more direct mediators of normal and diseased cellular processes. In this review article, we discuss current and emerging protein assays for improving cancer treatment, including trends toward assay miniaturization and measurement of protein activity.

In vitro assay for ACTH-releasing activity using ACTH radioimmunoassay. ACTH releasing activities by various drugs

Energy Technology Data Exchange (ETDEWEB)

Hashimoto, K; Takahara, J; Hosogi, H; Ofuji, N; Yasuhara, T [Okayama Univ. (Japan). School of Medicine

1976-02-01

This report deals with an in vitro assay of ACTH releasing activity utilizing pituitary incubation combined with ACTH radioimmunoassay. Half of a rat pituitary was preincubated in 2ml Krebs Ringer bicarbonate buffer containing 0.2% glucose and 0.25% BSA (KRBG-BSA) for 1.5 hr (45 min x 2). The medium was replaced by 1 ml KRBG-BSA and incubated for 30 min. Then the medium was again replaced by 1 ml KRBG-BSA or KRBG-BSA containing test materials and incubated for another 30 min. The amount of ACTH assayed by radioimmunoassay in the 2nd 30 min incubation was compared with that in the 1st 30 min incubation, and the result was expressed as a percentage. In the ACTH radioimmunoassay, anti-ACTH serum was diluted to 1:1,500-3,000. The /sup 125/I-..cap alpha../sup 1 -24/ACTH-antibody system was not affected by lysine-vasopressin (LVP), arginine-vasopressin (AVP), rat's pituitary LH, GH or prolactin. Human /sup 1 -39/ACTH was used as the ACTH standard. The dilution curve of the incubation medium was parallel to the standard curve. Reproducibility of immunoassayable ACTH within-assay was 174 +- 5.0 pg/tube (CV=2.9%). A log dose-relationship was observed between the amounts of stalk median eminence extracts (SME; NIAMDD) added to the incubation medium and its ACTH releasing activities. The sensitivity of this assay method was at least 0.1 SME or 10 mU of LVP and AVP. Using this method, it was found that LVP, AVP, norepinephrine (100 ng/ml--200 ng/ml) and 5-hydroxytryptophane (1 ..mu..g/ml) had ACTH releasing activities, but LH-RH, TRH, glucagon, dopamine, phentolamine, propranolol, haloperidol, prostaglandin E/sub 1/ and indomethacin did not affect the release of ACTH.

Glypican-3 level assessed by the enzyme-linked immunosorbent assay is inferior to alpha-fetoprotein level for hepatocellular carcinoma diagnosis.

Science.gov (United States)

Jeon, Yejoo; Jang, Eun Sun; Choi, Yun Suk; Kim, Jin-Wook; Jeong, Sook-Hyang

2016-09-01

Glypican-3 (GPC3) protein is highly expressed in hepatocellular carcinoma (HCC) tissue. It has been suggested as a diagnostic biomarker, but its inconsistent performance means that it requires further assessment. We therefore investigated the diagnostic value of the plasma GPC3 level compared to the alpha-fetoprotein (AFP) level as a diagnostic biomarker of HCC. We enrolled 157 consecutive patients with newly diagnosed HCC and 156 patients with liver cirrhosis (LC) as the control group. GPC3 plasma levels were measured using two commercially available enzyme-linked immunosorbent assays (ELISAs, named as Assay 1 and 2), and AFP levels were measured using an enzyme-linked chemiluminescent immunoassay. The diagnostic accuracy was analyzed using the receiver operating characteristics (ROC) curve. Plasma GPC3 levels in HCC patients were very low (0-3.09 ng/mL) in Assay 1, while only 3 of the 157 patients (1.9%) showed detectable GPC3 levels in Assay 2. The median GPC3 level was not significantly elevated in the HCC group (0.80 ng/mL) compared with the LC group (0.60 ng/mL). The area under the ROC curve (AUC) for GPC3 was 0.559 in Assay 1. In contrast, the median AFP level was significantly higher in HCC (27.72 ng/mL) than in LC (4.74 ng/mL), with an AUC of 0.729. The plasma level of GPC3 is a poor diagnostic marker for HCC, being far inferior to AFP. The development of a consistent detection system for the blood level of GPC3 is warranted.

Assaying Cellular Viability Using the Neutral Red Uptake Assay.

Science.gov (United States)

Ates, Gamze; Vanhaecke, Tamara; Rogiers, Vera; Rodrigues, Robim M

2017-01-01

The neutral red uptake assay is a cell viability assay that allows in vitro quantification of xenobiotic-induced cytotoxicity. The assay relies on the ability of living cells to incorporate and bind neutral red, a weak cationic dye, in lysosomes. As such, cytotoxicity is expressed as a concentration-dependent reduction of the uptake of neutral red after exposure to the xenobiotic under investigation. The neutral red uptake assay is mainly used for hazard assessment in in vitro toxicology applications. This method has also been introduced in regulatory recommendations as part of 3T3-NRU-phototoxicity-assay, which was regulatory accepted in all EU member states in 2000 and in the OECD member states in 2004 as a test guideline (TG 432). The present protocol describes the neutral red uptake assay using the human hepatoma cell line HepG2, which is often employed as an alternative in vitro model for human hepatocytes. As an example, the cytotoxicity of acetaminophen and acetyl salicylic acid is assessed.

Quantitative Real-Time PCR using the Thermo Scientific Solaris qPCR Assay

Science.gov (United States)

Ogrean, Christy; Jackson, Ben; Covino, James

2010-01-01

The Solaris qPCR Gene Expression Assay is a novel type of primer/probe set, designed to simplify the qPCR process while maintaining the sensitivity and accuracy of the assay. These primer/probe sets are pre-designed to >98% of the human and mouse genomes and feature significant improvements from previously available technologies. These improvements were made possible by virtue of a novel design algorithm, developed by Thermo Scientific bioinformatics experts. Several convenient features have been incorporated into the Solaris qPCR Assay to streamline the process of performing quantitative real-time PCR. First, the protocol is similar to commonly employed alternatives, so the methods used during qPCR are likely to be familiar. Second, the master mix is blue, which makes setting the qPCR reactions easier to track. Third, the thermal cycling conditions are the same for all assays (genes), making it possible to run many samples at a time and reducing the potential for error. Finally, the probe and primer sequence information are provided, simplifying the publication process. Here, we demonstrate how to obtain the appropriate Solaris reagents using the GENEius product search feature found on the ordering web site (www.thermo.com/solaris) and how to use the Solaris reagents for performing qPCR using the standard curve method. PMID:20567213

The survival of cultured mouse cerebellar granule cells is not dependent on elevated potassium-ion concentration

DEFF Research Database (Denmark)

Mogensen, Helle Smidt; Hack, N; Balázs, R

1994-01-01

The effects of K(+)-induced membrane depolarization were studied on the survival and biochemical parameters in mouse and rat cerebellar granule cells grown in micro-well cultures. Cell numbers were determined by estimating DNA content using the Hoechst 33258 fluorochrome binding assay. DNA from d...

Bond yield curve construction

Directory of Open Access Journals (Sweden)

Kožul Nataša

2014-01-01

Full Text Available In the broadest sense, yield curve indicates the market's view of the evolution of interest rates over time. However, given that cost of borrowing it closely linked to creditworthiness (ability to repay, different yield curves will apply to different currencies, market sectors, or even individual issuers. As government borrowing is indicative of interest rate levels available to other market players in a particular country, and considering that bond issuance still remains the dominant form of sovereign debt, this paper describes yield curve construction using bonds. The relationship between zero-coupon yield, par yield and yield to maturity is given and their usage in determining curve discount factors is described. Their usage in deriving forward rates and pricing related derivative instruments is also discussed.

Effects of gamma radiation on the OM431 human ocular melanoma cell line

International Nuclear Information System (INIS)

Logani, S.; Cho, A.S.; Su, L.D.; Withers, H.R.; McBride, W.H.; Hall, M.O.; Lee, D.A.; Milani, J.K.; Straatsma, B.R.

1995-01-01

In order to determine the dose responsiveness to radiation of ocular melanoma, we conducted an in vitro dose-response study on a monolayer cell culture using a clonogenic assay. The effects on cell survival were determined relative to unirradiated controls. A human epithelioid ocular melanoma cell line, OM431, was maintained in tissue culture and serial dilutions of viable cells were plated in flasks, allowed to settle and attach for 48 h, and subsequently irradiated with 1-10 Gy in single fractions. After 2 weeks, the number of reproducing clones (forming colonies with greater than 32 cells or five generations) were counted. The surviving fractions of cells were plotted on a cell survival curve using the linear quadratic model. The survival curve showed a large initial shoulder followed by an exponential decline in growth. Our data suggest that the OM431 ocular melanoma cell line responds to irradiation in a manner similar to other melanoma cell lines and is relatively radioresistent especially at lower doses. (author)

NSAID Antinociception Measured in a Chemical and a Thermal Assay in Mice

Directory of Open Access Journals (Sweden)

HF Miranda

2001-01-01

Full Text Available The antinociceptive activity of several nonsteroidal anti-inflammatory drugs (NSAIDs that were administered either intraperitoneally or intrathecally was assessed in mice by two algesiometric tests. The first was the writhing test, which assessed the abdominal constrictions that were induced by intraperitoneal acetic acid (a chemical test, and the second was the tail flick test, which measured pain responses to heat stimuli. The corresponding effective doses and their relative potencies were compared because these tests use different nociceptive stimuli with different transmission pathways. The intraperitoneal and intrathecal dose-response curves for the antinociception induced by every NSAID that was tested were parallel in the writhing test. In the tail flick test, however, only the intraperitoneal and intrathecal dose-response curves for ketoprofen, piroxicam, naproxen, nimesulide, paracetamol and diclofenac were parallel. The results obtained in this study confirm that NSAIDs possess different abilities to induce inhibition of cyclooxygenase, and they can be indirectly assessed by their different antinociceptive activities, depending on the algesiometric assays that are used. The antinociception of most NSAIDs might involve central mechanisms. The findings demonstrate the increasing importance of the spinal cord in processing and modulating nociceptive input, because intrathecal administration of NSAIDs is always more effective (in terms of potency than systemic administration; thus, the antinociceptive efficacy of NSAIDs strongly depends on the algesiometric assay that is used and on the type of the nociceptive stimulus to which the test subject is exposed.

Blood cells kinetics by stable tracers assayed by XRF-analysis and by radioactive tracers

International Nuclear Information System (INIS)

Cesareo, R.; Del Principe, D.; Tallarida, B.

1980-01-01

Stable rubidium, as an analogue of potassium, has been employed to label human and rabbit red cells and platelets. The concentration of rubidium bound to the cells, which are deposited on filter paper disks, is assayed by a simple version of the X-ray fluorescence equipment, characterized by a 1 mCi Cd-109 radioisotopic source, a xenon-filled proportional detector and a single-channel-analyzer. Survival curves of platelets and of red-cells labelled with stable Rb were determined by measuring the Rb concentration in the labelled cells, withdrawn at different times. The fluorescent counts are linearly proportional to the mass of rubidium per unit area of the filter. The sensitivity of the XRF technique is about 0.05 μg/cm 2 in a measuring time of 500 s. The mean quantity of Rb incorporated by the platelets is of about 5-10 μg for human platelets labelled ''in vitro'', of about 30-50 μg for rabbit platelets labelled in vivo and of about 0.5 mg for rabbit red cell labelled in vivo. The following half-time values were deduced: Tsub(1/2) = 35-45 h for human platelets labelled in ''in vitro''. Tsub(1/2) = 22 +- 3 h for rabbit platelets labelled ''in vivo''. Tsub(1/2) = 310 +- 15 h for rabbit red cells labelled ''in vivo''. The next step of our studies is to label ''in vivo'' human red cells and human platelets. (author)

In vivo Comet assay – statistical analysis and power calculations of mice testicular cells

DEFF Research Database (Denmark)

Hansen, Merete Kjær; Sharma, Anoop Kumar; Dybdahl, Marianne

2014-01-01

is to provide curves for this statistic outlining the number of animals and gels to use. The current study was based on 11 compounds administered via oral gavage in three doses to male mice: CAS no. 110-26-9, CAS no. 512-56-1, CAS no. 111873-33-7, CAS no. 79-94-7, CAS no. 115-96-8, CAS no. 598-55-0, CAS no. 636....... A linear mixed-effects model was fitted to the summarized data and the estimated variance components were used to generate power curves as a function of sample size. The statistic that most appropriately summarized the within-sample distributions was the median of the log-transformed data, as it most...... consistently conformed to the assumptions of the statistical model. Power curves for 1.5-, 2-, and 2.5-fold changes of the highest dose group compared to the control group when 50 and 100 cells were scored per gel are provided to aid in the design of future Comet assay studies on testicular cells....

Curve Digitizer – A software for multiple curves digitizing

Directory of Open Access Journals (Sweden)

Florentin ŞPERLEA

2010-06-01

Full Text Available The Curve Digitizer is software that extracts data from an image file representing a graphicand returns them as pairs of numbers which can then be used for further analysis and applications.Numbers can be read on a computer screen stored in files or copied on paper. The final result is adata set that can be used with other tools such as MSEXCEL. Curve Digitizer provides a useful toolfor any researcher or engineer interested in quantifying the data displayed graphically. The image filecan be obtained by scanning a document

Validation of an in vitro contractility assay using canine ventricular myocytes

Energy Technology Data Exchange (ETDEWEB)

Harmer, A.R., E-mail: alex.harmer@astrazeneca.com; Abi-Gerges, N.; Morton, M.J.; Pullen, G.F.; Valentin, J.P.; Pollard, C.E.

2012-04-15

Measurement of cardiac contractility is a logical part of pre-clinical safety assessment in a drug discovery project, particularly if a risk has been identified or is suspected based on the primary- or non-target pharmacology. However, there are limited validated assays available that can be used to screen several compounds in order to identify and eliminate inotropic liability from a chemical series. We have therefore sought to develop an in vitro model with sufficient throughput for this purpose. Dog ventricular myocytes were isolated using a collagenase perfusion technique and placed in a perfused recording chamber on the stage of a microscope at ∼ 36 °C. Myocytes were stimulated to contract at a pacing frequency of 1 Hz and a digital, cell geometry measurement system (IonOptix™) was used to measure sarcomere shortening in single myocytes. After perfusion with vehicle (0.1% DMSO), concentration–effect curves were constructed for each compound in 4–30 myocytes taken from 1 or 2 dog hearts. The validation test-set was 22 negative and 8 positive inotropes, and 21 inactive compounds, as defined by their effect in dog, cynolomolgous monkey or humans. By comparing the outcome of the assay to the known in vivo contractility effects, the assay sensitivity was 81%, specificity was 75%, and accuracy was 78%. With a throughput of 6–8 compounds/week from 1 cell isolation, this assay may be of value to drug discovery projects to screen for direct contractility effects and, if a hazard is identified, help identify inactive compounds. -- Highlights: ► Cardiac contractility is an important physiological function of the heart. ► Assessment of contractility is a logical part of pre-clinical drug safety testing. ► There are limited validated assays that predict effects of compounds on contractility. ► Using dog myocytes, we have developed an in vitro cardiac contractility assay. ► The assay predicted the in vivo contractility with a good level of accuracy.

NTCP modelling of lung toxicity after SBRT comparing the universal survival curve and the linear quadratic model for fractionation correction

International Nuclear Information System (INIS)

Wennberg, Berit M.; Baumann, Pia; Gagliardi, Giovanna

2011-01-01

Background. In SBRT of lung tumours no established relationship between dose-volume parameters and the incidence of lung toxicity is found. The aim of this study is to compare the LQ model and the universal survival curve (USC) to calculate biologically equivalent doses in SBRT to see if this will improve knowledge on this relationship. Material and methods. Toxicity data on radiation pneumonitis grade 2 or more (RP2+) from 57 patients were used, 10.5% were diagnosed with RP2+. The lung DVHs were corrected for fractionation (LQ and USC) and analysed with the Lyman- Kutcher-Burman (LKB) model. In the LQ-correction α/β = 3 Gy was used and the USC parameters used were: α/β = 3 Gy, D 0 = 1.0 Gy, n = 10, α 0.206 Gy-1 and d T = 5.8 Gy. In order to understand the relative contribution of different dose levels to the calculated NTCP the concept of fractional NTCP was used. This might give an insight to the questions of whether 'high doses to small volumes' or 'low doses to large volumes' are most important for lung toxicity. Results and Discussion. NTCP analysis with the LKB-model using parameters m = 0.4, D50 = 30 Gy resulted for the volume dependence parameter (n) with LQ correction n = 0.87 and with USC correction n = 0.71. Using parameters m = 0.3, D 50 = 20 Gy n = 0.93 with LQ correction and n 0.83 with USC correction. In SBRT of lung tumours, NTCP modelling of lung toxicity comparing models (LQ,USC) for fractionation correction, shows that low dose contribute less and high dose more to the NTCP when using the USC-model. Comparing NTCP modelling of SBRT data and data from breast cancer, lung cancer and whole lung irradiation implies that the response of the lung is treatment specific. More data are however needed in order to have a more reliable modelling

Reduction of bias in neutron multiplicity assay using a weighted point model

Energy Technology Data Exchange (ETDEWEB)

Geist, W. H. (William H.); Krick, M. S. (Merlyn S.); Mayo, D. R. (Douglas R.)

2004-01-01

sample and has an average neutron energy close to the O({alpha},n) average neutron energy. Better assay results can be obtained if there is some knowledge of the plutonium geometry, because weighting factor curves can be calculated for any specified geometry.

The Attainment of High Sensitivity and Precision in Radioimmunoassay Techniques as Exemplified in a Simple Assay of Serum Insulin

Energy Technology Data Exchange (ETDEWEB)

Albano, Janet; Ekins, R. P. [Institute of Nuclear Medicine, Middlesex Hospital Medical School, London (United Kingdom)

1970-02-15

Recent controversy has underlined the fundamental confusion surrounding the concepts of assay ''sensitivity'' and ''precision'' and, in particular, their optimization in radioimmunoassay and other saturation assay procedures. Many formal definitions of sensitivity (e.g. that laid down by the American Chemical Society) express this concept in terms of the slope of the ''dose'' response curve; nevertheless, in common usage, the term is normally regarded as a synonym for the detection limit of the measurement technique. However, a technique which is ''sensitive'' in the formal sense may not display a low limit of detection, and it is readily demonstrable that, in radioimmunoassay systems in particular, there are circumstances in which increase in the slope of the response curve may lead to an increase in the detection limit of the assay. The authors have based their insulin assay protocols on mathematical principles specifically designed to lead to the minimization of the detection limit. The method depends on the use of (uncoated) charcoal for the separation of free and bound labelled insulin in incubation mixtures in which insulin-free human serum is used as diluent. The detection limit of the method is approximately 1 pg/ml of incubation mixture, corresponding to roughly 0.25 {mu}U/ml of serum at the serum dilutions used. In a formal comparative study, the method has been shown to be more sensitive, precise and accurate than other methods relying on double antibody or chromato-electrophoietic separation. The relevance of such factors as high specific activity labelled hormone to the attainment of high sensitivity is discussed. (author)

ASTRO Research Fellow Presentation - A comparison of the comet assay and pulsed-field gel electrophoresis as a predictive assay for radiosensitivity in human fibroblasts

International Nuclear Information System (INIS)

Sarkaria, Jann N.; Eady, John J.; Peacock, John H.; Steel, G. Gordon

1996-01-01

Purpose/Objective: To determine whether neutral lysis single-cell gel electrophoresis (comet assay) or pulsed-field gel electrophoresis (PFGE) can be used as a predictive assay for tissue response to radiotherapy as an alternative to clonogenic survival measurements. Materials and Methods: The comet assay has been widely used to measure DNA double strand breaks (dsb) in individual cells, and it has been suggested that it could be used as an alternative to clonogenic assays to measure radiosensitivity. Previous studies in this lab have demonstrated the ability of pulsed-field gel electrophoresis, which also measures DNA dsb, to accurately predict the radiosensitivity of a panel of fibroblasts based on determination of residual DNA dsb. As part of an ongoing study examining the relationship between fibroblast radiosensitivity and normal-tissue radiation reactions, we have compared the sensitivity and accuracy of the comet assay and PFGE on a different panel of non-transformed fibroblasts derived from breast cancer patients who developed severe radiation late effects and from case-matched controls. For the measurement of initial damage, cells were suspended in PBS and irradiated on ice for the comet assay and irradiated in agarose plugs on ice for pFGE. Residual damage was measured following irradiation of confluent cultures at 37 degree sign C and subsequent incubation for four hours prior to preparation of agarose slides and plugs. All irradiations were performed with a 59 TBq 60 Co source at a dose rate of 1.7 Gy/min. Electrophoresis was performed following neutral pH cell lysis. Comet images were captured and analyzed using Optimas software with DNA damage quantitated by the comet moment. PFGE gels were analyzed using a phosphor-image analysis system and damage was quantitated based on the percent of activity released from the well. Results: The comet assay was able to detect initial DNA damage at a threshold of 5 Gy and exhibited a linear dose

Survival of a cohort of women with cervical cancer diagnosed in a Brazilian cancer center

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Claudio Calazan do Carmo

2011-08-01

Full Text Available OBJECTIVE: To assess overall survival of women with cervical cancer and describe prognostic factors associated. METHODS: A total of 3,341 cases of invasive cervical cancer diagnosed at the Brazilian Cancer Institute, Rio de Janeiro, southeastern Brazil, between 1999 and 2004 were selected. Clinical and pathological characteristics and follow-up data were collected. There were performed a survival analysis using Kaplan-Meier curves and a multivariate analysis through Cox model. RESULTS: Of all cases analyzed, 68.3% had locally advanced disease at the time of diagnosis. The 5-year overall survival was 48%. After multivariate analysis, tumor staging at diagnosis was the single variable significantly associated with prognosis (p<0.001. There was seen a dose-response relationship between mortality and clinical staging, ranging from 27.8 to 749.6 per 1,000 cases-year in women stage I and IV, respectively. CONCLUSIONS: The study showed that early detection through prevention programs is crucial to increase cervical cancer survival.

Flow cytometric determination of radiation-induced chromosome damage and its correlation with cell survival

International Nuclear Information System (INIS)

Welleweerd, J.; Wilder, M.E.; Carpenter, S.G.; Raju, M.R.

1984-01-01

Chinese hamster M3-1 cells were irradiated with several doses of x rays or α particles from 238 Pu. Propidium iodide-stained chromosome suspensions were prepared at different times after irradiation; cells were also assayed for survival. The DNA histograms of these chromosomes showed increased background counts with increased doses of radiation. This increase in background was cell-cycle dependent and was correlated with cell survival. The correlation between radiation-induced chromosome damage and cell survival was the same for X rays and α particles. Data are presented which indicate that flow cytometric analysis of chromosomes of irradiated cell populations can be a useful adjunct to classical cytogenic analysis of irradiation-induced chromosomal damage by virtue of its ability to express and measure chromosomal damage not seen by classical cytogenic methods

Estimates of DNA damage by the comet assay in the direct-developing frog Eleutherodactylus johnstonei (Anura, Eleutherodactylidae

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Laura Carolina Valencia

2011-01-01

Full Text Available The aim of this study was to use the Comet assay to assess genetic damage in the direct-developing frog Eleutherodactylus johnstonei. A DNA diffusion assay was used to evaluate the effectiveness of alkaline, enzymatic and alkaline/enzymatic treatments for lysing E. johnstonei blood cells and to determine the amount of DNA strand breakage associated with apoptosis and necrosis. Cell sensitivity to the mutagens bleomycin (BLM and 4-nitroquinoline-1-oxide (4NQO was also assessed using the Comet assay, as was the assay reproducibility. Alkaline treatment did not lyse the cytoplasmic and nuclear membranes of E. johnstonei blood cells, whereas enzymatic digestion with proteinase K (40 !g/mL yielded naked nuclei. The contribution of apoptosis and necrosis (assessed by the DNA diffusion assay to DNA damage was estimated to range from 0% to 8%. BLM and 4NQO induced DNA damage in E. johnstonei blood cells at different concentrations and exposure times. Dose-effect curves with both mutagens were highly reproducible and showed consistently low coefficients of variation (CV < 10%. The results are discussed with regard to the potential use of the modified Comet assay for assessing the exposure of E. johnstonei to herbicides in ecotoxicological studies.

Estimates of DNA damage by the comet assay in the direct-developing frog Eleutherodactylus johnstonei (Anura, Eleutherodactylidae).

Science.gov (United States)

Valencia, Laura Carolina; García, Adriana; Ramírez-Pinilla, Martha Patricia; Fuentes, Jorge Luis

2011-10-01

The aim of this study was to use the Comet assay to assess genetic damage in the direct-developing frog Eleutherodactylus johnstonei. A DNA diffusion assay was used to evaluate the effectiveness of alkaline, enzymatic and alkaline/enzymatic treatments for lysing E. johnstonei blood cells and to determine the amount of DNA strand breakage associated with apoptosis and necrosis. Cell sensitivity to the mutagens bleomycin (BLM) and 4-nitro-quinoline-1-oxide (4NQO) was also assessed using the Comet assay, as was the assay reproducibility. Alkaline treatment did not lyse the cytoplasmic and nuclear membranes of E. johnstonei blood cells, whereas enzymatic digestion with proteinase K (40 μg/mL) yielded naked nuclei. The contribution of apoptosis and necrosis (assessed by the DNA diffusion assay) to DNA damage was estimated to range from 0% to 8%. BLM and 4NQO induced DNA damage in E. johnstonei blood cells at different concentrations and exposure times. Dose-effect curves with both mutagens were highly reproducible and showed consistently low coefficients of variation (CV ≤ 10%). The results are discussed with regard to the potential use of the modified Comet assay for assessing the exposure of E. johnstonei to herbicides in ecotoxicological studies.

Estimating reaction rate constants: comparison between traditional curve fitting and curve resolution

NARCIS (Netherlands)

Bijlsma, S.; Boelens, H. F. M.; Hoefsloot, H. C. J.; Smilde, A. K.

2000-01-01

A traditional curve fitting (TCF) algorithm is compared with a classical curve resolution (CCR) approach for estimating reaction rate constants from spectral data obtained in time of a chemical reaction. In the TCF algorithm, reaction rate constants an estimated from the absorbance versus time data

A catalog of special plane curves

CERN Document Server

Lawrence, J Dennis

2014-01-01

Among the largest, finest collections available-illustrated not only once for each curve, but also for various values of any parameters present. Covers general properties of curves and types of derived curves. Curves illustrated by a CalComp digital incremental plotter. 12 illustrations.

Herpes Murine Model as a Biological Assay to Test Dialyzable Leukocyte Extracts Activity

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Nohemí Salinas-Jazmín

2015-01-01

Full Text Available Human dialyzable leukocyte extracts (DLEs are heterogeneous mixtures of low-molecular-weight peptides that are released on disruption of peripheral blood leukocytes from healthy donors. DLEs improve clinical responses in infections, allergies, cancer, and immunodeficiencies. Transferon is a human DLE that has been registered as a hemoderivate by Mexican health authorities and commercialized nationally. To develop an animal model that could be used routinely as a quality control assay for Transferon, we standardized and validated a murine model of cutaneous HSV-1 infection. Using this model, we evaluated the activity of 27 Transferon batches. All batches improved the survival of HSV-1-infected mice, wherein average survival rose from 20.9% in control mice to 59.6% in Transferon-treated mice. The activity of Transferon correlated with increased serum levels of IFN-γ and reduced IL-6 and TNF-α concentrations. Our results demonstrate that (i this mouse model of cutaneous herpes can be used to examine the activity of DLEs, such as Transferon; (ii the assay can be used as a routine test for batch release; (iii Transferon is produced with high homogeneity between batches; (iv Transferon does not have direct virucidal, cytoprotective, or antireplicative effects; and (v the protective effect of Transferon in vivo correlates with changes in serum cytokines.

Intersection numbers of spectral curves

CERN Document Server

Eynard, B.

2011-01-01

We compute the symplectic invariants of an arbitrary spectral curve with only 1 branchpoint in terms of integrals of characteristic classes in the moduli space of curves. Our formula associates to any spectral curve, a characteristic class, which is determined by the laplace transform of the spectral curve. This is a hint to the key role of Laplace transform in mirror symmetry. When the spectral curve is y=\\sqrt{x}, the formula gives Kontsevich--Witten intersection numbers, when the spectral curve is chosen to be the Lambert function \\exp{x}=y\\exp{-y}, the formula gives the ELSV formula for Hurwitz numbers, and when one chooses the mirror of C^3 with framing f, i.e. \\exp{-x}=\\exp{-yf}(1-\\exp{-y}), the formula gives the Marino-Vafa formula, i.e. the generating function of Gromov-Witten invariants of C^3. In some sense this formula generalizes ELSV, Marino-Vafa formula, and Mumford formula.

Adenosine triphosphate-based chemotherapy response assay (ATP-CRA)-guided platinum-based 2-drug chemotherapy for unresectable nonsmall-cell lung cancer.

Science.gov (United States)

Moon, Yong Wha; Choi, Sung Ho; Kim, Yong Tai; Sohn, Joo Hyuk; Chang, Joon; Kim, Se Kyu; Park, Moo Suk; Chung, Kyung Young; Lee, Hyoun Ju; Kim, Joo-Hang

2007-05-01

The study investigated correlations between adenosine triphosphate / chemotherapy response assay (ATP-CRA) and clinical outcomes after ATP-CRA-guided platinum-based chemotherapy for unresectable nonsmall-cell lung cancer (NSCLC). The authors performed an in vitro chemosensitivity test, ATP-CRA, to evaluate the chemosensitivities of anticancer drugs such as cisplatin, carboplatin, paclitaxel, docetaxel, gemcitabine, and vinorelbine for chemonaive, unresectable NSCLC. The cell death rate was determined by measuring the intracellular ATP levels of drug-exposed cells compared with untreated controls. A sensitive drug was defined as a drug producing 30% or more reduction in ATP compared with untreated controls. Assay-guided platinum-based 2-drug chemotherapy was given to patients with pathologically confirmed NSCLC. Thirty-four patients were enrolled. Thirty tumor specimens were obtained by bronchoscopic biopsies and 4 obtained surgically. The median age was 61 years and 27 patients had an Eastern Cooperative Oncology Group (ECOG) performance status of 0-1. The response rate was 43.8%. At a median follow-up period of 16.9 months, the median progression-free and overall survivals were 3.6 and 11.2 months, respectively. Patients were dichotomized into the platinum-sensitive (S; 20 patients) and resistant (R; 14 patients) groups. The positive/negative predictive values were 61.1% and 78.6% with a predictive accuracy of 68.8%. Although without significant differences in pretreatment parameters, the S-group showed better clinical response (P=.036), longer progression-free survival (P=.060), and longer overall survival (P=.025). Despite using bronchoscopic biopsied specimens, ATP-CRA and clinical outcomes correlated well after assay-guided platinum-based 2-drug chemotherapy for unresectable NSCLC. There was a favorable response and survival in the platinum-sensitive vs resistant groups. Copyright (c) 2007 American Cancer Society

Sensitivity and Selectivity on Aptamer-Based Assay: The Determination of Tetracycline Residue in Bovine Milk

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Sohee Jeong

2012-01-01

Full Text Available A competitive enzyme-linked aptamer assay (ELAA to detect tetracycline in milk was performed by using two different aptamers individually; one is 76 mer-DNA aptamer and the other is 57 mer-RNA aptamer. The best optimum condition was obtained without monovalent ion, Na+ and also by adding no Mg2+ ion in the assay buffer, along with RT incubation. The optimized ELAA showed a good sensitivity (LOD of 2.10 × 10−8 M with a wide dynamic range (3.16 × 10−8 M ~ 3.16 × 10−4 M. In addition, the average R.S.D. across all data points of the curve was less than 2.5% with good recoveries (~101.8% from the milk media. Thus, this method provides a good tool to monitor tetracycline in milk from MRLs’ point of view. However, this ELAA method was not superior to the ELISA method in terms of specificity. This paper describes that it does not always give better sensitivity and specificity in assays even though aptamers have several advantages over antibodies and have been known to be good binders for binding assays.

Differential responses to radiation and hyperthermia of cloned cell lines derived from a single human melanoma xenograft

International Nuclear Information System (INIS)

Rofstad, E.K.; Brustad, T.

1984-01-01

One uncloned and five cloned cell lines were derived from a single human melanoma xenograft. Cells from passages 7-12 were exposed to either radiation or hyperthermia (42.5 0 C, pH = 7.4) under aerobic conditions and the colony forming ability of the cells was assayed in soft agar. The five cloned lines showed individual and characteristic responses to radiation as well as to hyperthermia. The variation in the response to radiation was mainly reflected in the size of the shoulders of the survival curves rather than in the D 0 -values. The variation in the response to hyperthermia was mainly reflected in the terminal slopes of the survival curves. The survival curve of cells from the uncloned line, both when exposed to radiation and hyperthermia, was positioned in the midst of those of the cloned lines. The response of the cloned lines to radiation did not correlate with the response to hyperthermia, indicating that tumor cell subpopulations which are resistant to radiation may respond well to hyperthermia

Action of caffeine on the survival of x-irradiated cells

International Nuclear Information System (INIS)

Busse, P.M.

1978-01-01

Post-irradiation treatment of HeLa S3 cells with 1 mM caffeine results in a marked diminution of the surviving fraction as scored by colony formation. The decrease is dose-dependent; the effect of a 24-h post-irradiation treatment of a non-synchronous population with caffeine is to change the terminal slope of the survival curve and its intercept. Do is reduced from 130 to 60 rad; the extrapolation number is increased about twofold. The amount of post-irradiation killing is maximal if cells are exposed to caffeine at a concentration of at least 1 mM for 8 hours; less than 10% of unirradiated cells are killed under these conditions. Dose-response curves were also obtained for synchronous cells at various phases of the cell cycle. Similar results were obtained at all cell ages, but the magnitude of the effect is age-dependent. This age dependence was further explored in experiments in which mitotically collected cells were exposed to 300 or 500 rad doses at 2-hour intervals throughout the cell cycle. Treatment with caffeine for 24 hours after irradiation enhances the killing of cells late in the cycle more than in G 1 . The sensitivities of two other cell lines, CHO and EMT6, also were examined; both are substantially less sensitive to caffeine. The smaller cell-cycle dependence of CHO cells is qualitatively the same as that of HeLa cells

Elliptic curves for applications (Tutorial)

NARCIS (Netherlands)

Lange, T.; Bernstein, D.J.; Chatterjee, S.

2011-01-01

More than 25 years ago, elliptic curves over finite fields were suggested as a group in which the Discrete Logarithm Problem (DLP) can be hard. Since then many researchers have scrutinized the security of the DLP on elliptic curves with the result that for suitably chosen curves only exponential

Differential geometry and topology of curves

CERN Document Server

Animov, Yu

2001-01-01

Differential geometry is an actively developing area of modern mathematics. This volume presents a classical approach to the general topics of the geometry of curves, including the theory of curves in n-dimensional Euclidean space. The author investigates problems for special classes of curves and gives the working method used to obtain the conditions for closed polygonal curves. The proof of the Bakel-Werner theorem in conditions of boundedness for curves with periodic curvature and torsion is also presented. This volume also highlights the contributions made by great geometers. past and present, to differential geometry and the topology of curves.

Models of genus one curves

OpenAIRE

Sadek, Mohammad

2010-01-01

In this thesis we give insight into the minimisation problem of genus one curves defined by equations other than Weierstrass equations. We are interested in genus one curves given as double covers of P1, plane cubics, or complete intersections of two quadrics in P3. By minimising such a curve we mean making the invariants associated to its defining equations as small as possible using a suitable change of coordinates. We study the non-uniqueness of minimisations of the genus one curves des...

The crime kuznets curve

OpenAIRE

Buonanno, Paolo; Fergusson, Leopoldo; Vargas, Juan Fernando

2014-01-01

We document the existence of a Crime Kuznets Curve in US states since the 1970s. As income levels have risen, crime has followed an inverted U-shaped pattern, first increasing and then dropping. The Crime Kuznets Curve is not explained by income inequality. In fact, we show that during the sample period inequality has risen monotonically with income, ruling out the traditional Kuznets Curve. Our finding is robust to adding a large set of controls that are used in the literature to explain the...

Impact of temperature and soil type on Mycobacterium bovis survival in the environment.

Science.gov (United States)

Barbier, Elodie; Rochelet, Murielle; Gal, Laurent; Boschiroli, Maria Laura; Hartmann, Alain

2017-01-01

Mycobacterium bovis, the causative agent of the bovine tuberculosis (bTB), mainly affects cattle, its natural reservoir, but also a wide range of domestic and wild mammals. Besides direct transmission via contaminated aerosols, indirect transmission of the M. bovis between wildlife and livestock might occur by inhalation or ingestion of environmental substrates contaminated through infected animal shedding. We monitored the survival of M. bovis in two soil samples chosen for their contrasted physical and-chemical properties (i.e. pH, clay content). The population of M. bovis spiked in sterile soils was enumerated by a culture-based method after 14, 30, 60, 90, 120 and 150 days of incubation at 4°C and 22°C. A qPCR based assay targeting the IS1561' locus was also performed to monitor M. bovis in both sterile and biotic spiked soils. The analysis of survival profiles using culture-based method showed that M. bovis survived longer at lower temperature (4°C versus 22°C) whereas the impact of soil characteristics on M. bovis persistence was not obvious. Furthermore, qPCR-based assay detected M. bovis for a longer period of time than the culture based method with higher gene copy numbers observed in sterile soils than in biotic ones. Impact of soil type on M. bovis persistence need to be deepened in order to fill the gap of knowledge concerning indirect transmission of the disease.

Effects of depleted uranium on the health and survival of Ceriodaphnia dubia and Hyalella azteca

Science.gov (United States)

Kuhne, W.W.; Caldwell, C.A.; Gould, W.R.; Fresquez, P.R.; Finger, S.

2002-01-01

Depleted uranium (DU) has been used as a substitute for the fissionable enriched uranium component of atomic weapons tested at Los Alamos National Laboratory (LANL) (Los Alamos, NM, USA) since the early 1950s, resulting in considerable concentrations of DU in the soils within the test sites. Although the movement of DU into major aquatic systems has been shown to be minimal, there are many small-order ephemeral streams and areas of standing water in canyons throughout LANL that may be affected by inputs of DU via runoff, erosion, and leaching. Ninety-six-hour acute and 7-d chronic toxicity assays were conducted to measure the toxicity of DU on survival and reproduction of Ceriodaphnia dubia. A 14-d water-only assay was conducted to measure survival and growth of Hyalella azteca. The estimated median lethal concentration (LC50) to produce 50% mortality of the test population for the 96-h Ceriodaphnia dubia assay was 10.50 mg/L. Reproductive effects occurred at a lowest-observable-effect concentration ???3.91 mg/L with a no-observable-effect concentration of 1.97 mg/L. The estimated 14-d LC50 for the Hyalella azteca assay was 1.52 mg/L No significant relationship was detected between growth and DU concentrations. Concentrations at which toxicity effects were observed in this study for both invertebrates exceeded concentrations of total uranium observed in runoff from LANL lands. Thus, it is likely that current runoff levels of uranium do not pose a threat to these types of aquatic invertebrates.

Matrix effects of TRU [transuranic] assays using the SWEPP PAN assay system

International Nuclear Information System (INIS)

Smith, J.R.

1990-08-01

The Drum Assay System (DAS) at the Stored Waste Experimental Pilot Plant (SWEPP) is a second-generation active-passive neutron assay system. It has been used to assay over 5000 208-liter drums of transuranic waste from the Rocky Flats Plant (RFP). Data from these assays have been examined and compared with the assays performed at Rocky Flats, mainly utilize counting of 239 Pu gamma rays. For the most part the passive assays are in very good agreement with the Rocky Flats assays. The active assays are strongly correlated with the results of the other two methods, but require matrix-dependent correction factors beyond those provided by the system itself. A set of matrix-dependent correction factors has been developed from the study of the assay results. 3 refs., 4 figs., 3 tabs

Prognostic Factors and Decision Tree for Long-term Survival in Metastatic Uveal Melanoma.

Science.gov (United States)

Lorenzo, Daniel; Ochoa, María; Piulats, Josep Maria; Gutiérrez, Cristina; Arias, Luis; Català, Jaum; Grau, María; Peñafiel, Judith; Cobos, Estefanía; Garcia-Bru, Pere; Rubio, Marcos Javier; Padrón-Pérez, Noel; Dias, Bruno; Pera, Joan; Caminal, Josep Maria

2017-12-04

The purpose of this study was to demonstrate the existence of a bimodal survival pattern in metastatic uveal melanoma. Secondary aims were to identify the characteristics and prognostic factors associated with long-term survival and to develop a clinical decision tree. The medical records of 99 metastatic uveal melanoma patients were retrospectively reviewed. Patients were classified as either short (≤ 12 months) or long-term survivors (> 12 months) based on a graphical interpretation of the survival curve after diagnosis of the first metastatic lesion. Ophthalmic and oncological characteristics were assessed in both groups. Of the 99 patients, 62 (62.6%) were classified as short-term survivors, and 37 (37.4%) as long-term survivors. The multivariate analysis identified the following predictors of long-term survival: age ≤ 65 years (p=0.012) and unaltered serum lactate dehydrogenase levels (p=0.018); additionally, the size (smaller vs. larger) of the largest liver metastasis showed a trend towards significance (p=0.063). Based on the variables significantly associated with long-term survival, we developed a decision tree to facilitate clinical decision-making. The findings of this study demonstrate the existence of a bimodal survival pattern in patients with metastatic uveal melanoma. The presence of certain clinical characteristics at diagnosis of distant disease is associated with long-term survival. A decision tree was developed to facilitate clinical decision-making and to counsel patients about the expected course of disease.

Comparison of Batch Assay and Random Assay Using Automatic Dispenser in Radioimmunoassay

Energy Technology Data Exchange (ETDEWEB)

Moon, Seung Hwan; Jang, Su Jin; Kang, Ji Yeon; Lee, Dong Soo; Chung, June Key; Lee, Myung Chul [Seoul Metropolitan Government Seoul National University Boramae Medical Center, Seoul (Korea, Republic of); Lee, Ho Young; Shin, Sun Young; Min, Gyeong Sun; Lee, Hyun Joo [Seoul National University college of Medicine, Seoul (Korea, Republic of)

2009-08-15

Radioimmunoassay (RIA) was usually performed by the batch assay. To improve the efficiency of RIA without increase of the cost and time, random assay could be a choice. We investigated the possibility of the random assay using automatic dispenser by assessing the agreement between batch assay and random assay. The experiments were performed with four items; Triiodothyronine (T3), free thyroxine (fT4), Prostate specific antigen (PSA), Carcinoembryonic antigen (CEA). In each item, the sera of twenty patients, the standard, and the control samples were used. The measurements were done 4 times with 3 hour time intervals by random assay and batch assay. The coefficient of variation (CV) of the standard samples and patients' data in T3, fT4, PSA, and CEA were assessed. ICC (Intraclass correlation coefficient) and coefficient of correlation were measured to assessing the agreement between two methods. The CVs (%) of T3, fT4, PSA, and CEA measured by batch assay were 3.2+-1.7%, 3.9+-2.1%, 7.1+-6.2%, 11.2+-7.2%. The CVs by random assay were 2.1+-1.7%, 4.8+-3.1%, 3.6+-4.8%, and 7.4+-6.2%. The ICC between the batch assay and random assay were 0.9968 (T3), 0.9973 (fT4), 0.9996 (PSA), and 0.9901 (CEA). The coefficient of correlation between the batch assay and random assay were 0.9924(T3), 0.9974 (fT4), 0.9994 (PSA), and 0.9989 (CEA) (p<0.05). The results of random assay showed strong agreement with the batch assay in a day. These results suggest that random assay using automatic dispenser could be used in radioimmunoassay

Comparison of Batch Assay and Random Assay Using Automatic Dispenser in Radioimmunoassay

International Nuclear Information System (INIS)

Moon, Seung Hwan; Jang, Su Jin; Kang, Ji Yeon; Lee, Dong Soo; Chung, June Key; Lee, Myung Chul; Lee, Ho Young; Shin, Sun Young; Min, Gyeong Sun; Lee, Hyun Joo

2009-01-01

Radioimmunoassay (RIA) was usually performed by the batch assay. To improve the efficiency of RIA without increase of the cost and time, random assay could be a choice. We investigated the possibility of the random assay using automatic dispenser by assessing the agreement between batch assay and random assay. The experiments were performed with four items; Triiodothyronine (T3), free thyroxine (fT4), Prostate specific antigen (PSA), Carcinoembryonic antigen (CEA). In each item, the sera of twenty patients, the standard, and the control samples were used. The measurements were done 4 times with 3 hour time intervals by random assay and batch assay. The coefficient of variation (CV) of the standard samples and patients' data in T3, fT4, PSA, and CEA were assessed. ICC (Intraclass correlation coefficient) and coefficient of correlation were measured to assessing the agreement between two methods. The CVs (%) of T3, fT4, PSA, and CEA measured by batch assay were 3.2±1.7%, 3.9±2.1%, 7.1±6.2%, 11.2±7.2%. The CVs by random assay were 2.1±1.7%, 4.8±3.1%, 3.6±4.8%, and 7.4±6.2%. The ICC between the batch assay and random assay were 0.9968 (T3), 0.9973 (fT4), 0.9996 (PSA), and 0.9901 (CEA). The coefficient of correlation between the batch assay and random assay were 0.9924(T3), 0.9974 (fT4), 0.9994 (PSA), and 0.9989 (CEA) (p<0.05). The results of random assay showed strong agreement with the batch assay in a day. These results suggest that random assay using automatic dispenser could be used in radioimmunoassay

The shape of dose-effect curves for diploid yeast cells irradiated with ionizing particles

International Nuclear Information System (INIS)

Pohlit, W.

1975-01-01

In a cybernetic model for the radiation reactions in eukaryotic cells, after irradiation they are assumed to be in one of three states: (a) viable cells; (b) with repairable damage; and (c) with irreparable damage. Two biological counter reactions with certain time constants can be observed: (i) recovery from sublethal damage; and (ii) repair of potential lethal damage. The shape of the dose-effect curve is influenced in a characteristic way by the different occupation of these states of the cells and by the time constants of the biological counter reactions. The biochemical analysis of the biological counter reactions, recovery and repair, has shown that both are linked together by the energy pool in the cell. In this way changes in the slope of the dose-effect curve due to different metabolic states of the cells can be understood quantitatively. Also the complicated dependence of survival cells on the absorbed dose rate over a wide range can be explained quantitatively. (author)

A Fast, Sensitive and Accurate High Resolution Melting (HRM Technology-Based Assay to Screen for Common K-ras Mutations

Directory of Open Access Journals (Sweden)

D. Kramer

2009-01-01

Full Text Available Background: Increasing evidence points to a negative correlation between K-ras mutations and patient’s response to, or survival benefit after, treatment with EGFR-inhibitors. Therefore, rapid and reliable assays for mutational analysis of the K-ras gene are strongly needed.

ROBUST DECLINE CURVE ANALYSIS

Directory of Open Access Journals (Sweden)

Sutawanir Darwis

2012-05-01

Full Text Available Empirical decline curve analysis of oil production data gives reasonable answer in hyperbolic type curves situations; however the methodology has limitations in fitting real historical production data in present of unusual observations due to the effect of the treatment to the well in order to increase production capacity. The development ofrobust least squares offers new possibilities in better fitting production data using declinecurve analysis by down weighting the unusual observations. This paper proposes a robustleast squares fitting lmRobMM approach to estimate the decline rate of daily production data and compares the results with reservoir simulation results. For case study, we usethe oil production data at TBA Field West Java. The results demonstrated that theapproach is suitable for decline curve fitting and offers a new insight in decline curve analysis in the present of unusual observations.

Survival Analysis and its Associated Factors of Beta Thalassemia Major in Hamadan Province

Directory of Open Access Journals (Sweden)

Reza Zamani

2015-05-01

Full Text Available Background: There currently is a lack of knowledge about the long-term survival of patients with beta thalassemia (BT, particularly in regions with low incidence of the disease. The aim of the present study was to determine the survival rate of the patients with BT major and the factors associated with the survival time. Methods: This retrospective cohort study was performed in Hamadan province, located in the west of Iran. The study included patients that referred to the provincial hospitals during 16 year period from 1997 to 2013. The follow up of each subject was calculated from the date of birth to the date of death. Demographic and clinical data were extracted from patients’ medical records using a checklist. Statistical analysis included the Kaplan-Meier method to analyze survivals, log-rank to compare curves between groups, and Cox regression for multivariate prognostic analysis. Results: A total of 133 patients with BT major were enrolled, 54.9% of whom were male and 66.2% were urban. The 10-, 20- and 30-year survival rate for all patients were 98.3%, 88.4% and 80.5%, respectively. Based on hazard ratio (HR, we found that accompanied diseases (P=0.01, blood type (P=0.03 and residency status (P=0.01 were significant predictors for the survival time of patients. Conclusion: The survival rate of BT patients has improved. Future researches such as prospective designs are required for the estimation of survival rate and to find other prognostic factors, which have reliable sources of data.

Collaborative study for the validation of an improved HPLC assay for recombinant IFN-alfa-2.

Science.gov (United States)

Jönsson, K H; Daas, A; Buchheit, K H; Terao, E

2016-01-01

The current European Pharmacopoeia (Ph. Eur.) texts for Interferon (IFN)-alfa-2 include a nonspecific photometric protein assay using albumin as calibrator and a highly variable cell-based assay for the potency determination of the protective effects. A request was expressed by the Official Medicines Control Laboratories (OMCLs) for improved methods for the batch control of recombinant interferon alfa-2 bulk and market surveillance testing of finished products, including those formulated with Human Serum Albumin (HSA). A HPLC method was developed at the Medical Products Agency (MPA, Sweden) for the testing of IFN-alfa-2 products. An initial collaborative study run under the Biological Standardisation Programme (BSP; study code BSP039) revealed the need for minor changes to improve linearity of the calibration curves, assay reproducibility and robustness. The goal of the collaborative study, coded BSP071, was to transfer and further validate this improved HPLC method. Ten laboratories participated in the study. Four marketed IFN-alfa-2 preparations (one containing HSA) together with the Ph. Eur. Chemical Reference Substance (CRS) for IFN-alfa-2a and IFN-alfa-2b, and in-house reference standards from two manufacturers were used for the quantitative assay. The modified method was successfully transferred to all laboratories despite local variation in equipment. The resolution between the main and the oxidised forms of IFN-alfa-2 was improved compared to the results from the BSP039 study. The improved method even allowed partial resolution of an extra peak after the principal peak. Symmetry of the main IFN peak was acceptable for all samples in all laboratories. Calibration curves established with the Ph. Eur. IFN-alfa-2a and IFN-alfa-2b CRSs showed excellent linearity with intercepts close to the origin and coefficients of determination greater than 0.9995. Assay repeatability, intermediate precision and reproducibility varied with the tested sample within acceptable

NEW CONCEPTS AND TEST METHODS OF CURVE PROFILE AREA DENSITY IN SURFACE: ESTIMATION OF AREAL DENSITY ON CURVED SPATIAL SURFACE

OpenAIRE

Hong Shen

2011-01-01

The concepts of curve profile, curve intercept, curve intercept density, curve profile area density, intersection density in containing intersection (or intersection density relied on intersection reference), curve profile intersection density in surface (or curve intercept intersection density relied on intersection of containing curve), and curve profile area density in surface (AS) were defined. AS expressed the amount of curve profile area of Y phase in the unit containing surface area, S...

Cell Survival in irradiation mouse intestine is increased by DNA-Binding radioprotectors

International Nuclear Information System (INIS)

Coultas, P.; Martin, R.

1996-01-01

Crypt survival in the mouse intestine has been used to examine effects of bisbenzimide radioprotectors. Intravenous delivery has been used for the present study in which the effects of methyl proamine (MP), a second generation Hoechst 33342 analogue have been examined. Recent results using the lung model suggest that MP is both more potent as a protector and less toxic than H 33342. The rapid nature of the crypt microcolony survival assay in mouse intestine provides an efficient way to examining factors which could impinge on the extent of radioprotection, for example, the interval between protector administration and radiation exposure. The data clearly show that for MP at 100 mg/kg, there is substantially increased crypt survival equivalent to a dose modification of about 1.33. The crypt scoring methods used indicate that protection is throughout the small intestine and preliminary data indicate that colon is also protected to a similar or slightly greater extent

M-curves and symmetric products

Indian Academy of Sciences (India)

Indranil Biswas

2017-08-03

Aug 3, 2017 ... is bounded above by g + 1, where g is the genus of X [11]. Curves which have exactly the maximum number (i.e., genus +1) of components of the real part are called M-curves. Classifying real algebraic curves up to homeomorphism is straightforward, however, classifying even planar non-singular real ...

A comparative study of PD-L1 immunohistochemical assays with four reliable antibodies in thymic carcinoma.

Science.gov (United States)

Sakane, Tadashi; Murase, Takayuki; Okuda, Katsuhiro; Takino, Hisashi; Masaki, Ayako; Oda, Risa; Watanabe, Takuya; Kawano, Osamu; Haneda, Hiroshi; Moriyama, Satoru; Saito, Yushi; Yamada, Takeshi; Nakanishi, Ryoichi; Inagaki, Hiroshi

2018-01-23

Currently, four immunohistochemical assays are registered with the US Food and Drug Administration to detect the expression of PD-L1. We investigated the PD-L1 expression in thymic carcinomas using these four diagnostic assays. The cases of 53 patients were reviewed and their specimens were subjected to four PD-L1 assays with different antibodies (SP142, SP263, 22C3, and 28-8). The PD-L1 expression in tumor cells (TCs) and immune cells (ICs) was evaluated. In TCs, the four assays showed similar scores in each case. Histopathologically, high TC scores were observed in squamous cell carcinomas (SqCCs). Meanwhile, there were no significant relationships among the IC scores in the four assays. In SqCCs, the high expression of PD-L1 (defined as ≥50% TC score) in TCs tended to be associated with early stage cancer. The patients with high expression levels of PD-L1 tended to show longer overall survival in the 22C3 assays (p=0.0200). In thymic carcinomas, the staining pattern showed high concordance among the four assays when TCs - rather than ICs - were stained. High PD-L1 positivity in TCs, especially in SqCCs, indicated that PD-1/PD-L1 targeted therapy may be a promising therapeutic approach.

Cellular radiosensitivity and DNA damage in primary human fibroblasts

International Nuclear Information System (INIS)

Wurm, R.; Burnet, N.G.; Duggal, N.

1994-01-01

To evaluate the relationship between radiation-induced cell survival and DNA damage in primary human fibroblasts to decide whether the initial or residual DNA damage levels are more predictive of normal tissue cellular radiosensitivity. Five primary human nonsyndromic and two primary ataxia telangiectasia fibroblast strains grown in monolayer were studied. Cell survival was assessed by clonogenic assay. Irradiation was given at high dose rate (HDR) 1-2 Gy/min. DNA damage was measured in stationary phase cells and expressed as fraction released from the well by pulsed-field gel electrophoresis (PFGE). For initial damage, cells were embedded in agarose and irradiated at HDR on ice. Residual DNA damage was measured in monolayer by allowing a 4-h repair period after HDR irradiation. Following HDR irradiation, cell survival varied between SF 2 0.025 to 0.23. Measurement of initial DNA damage demonstrated linear induction up to 30 Gy, with small differences in the slope of the dose-response curve between strains. No correlation between cell survival and initial damage was found. Residual damage increased linearly up to 80 Gy with a variation in slope by a factor of 3.2. Cell survival correlated with the slope of the dose-response curves for residual damage of the different strains (p = 0.003). The relationship between radiation-induced cell survival and DNA damage in primary human fibroblasts of differing radiosensitivity is closest with the amount of DNA damage remaining after repair. If assays of DNA damage are to be used as predictors of normal tissue response to radiation, residual DNA damage provides the most likely correlation with cell survival. 52 refs., 5 figs., 2 tabs

High resolution melting curve analysis as a new tool for rapid identification of canine parvovirus type 2 strains.

Science.gov (United States)

Bingga, Gali; Liu, Zhicheng; Zhang, Jianfeng; Zhu, Yujun; Lin, Lifeng; Ding, Shuangyang; Guo, Pengju

2014-01-01

A high resolution melting (HRM) curve method was developed to identify canine parvovirus type 2 (CPV-2) strains by nested PCR. Two sets of primers, CPV-426F/426R and CPV-87R/87F, were designed that amplified a 52 bp and 53 bp product from the viral VP2 capsid gene. The region amplified by CPV-426F/426R included the A4062G and T4064A mutations in CPV-2a, CPV-2b and CPV-2c. The region amplified by CPV-87F/87R included the A3045T mutation in the vaccine strains of CPV-2 and CPV-2a, CPV-2b and CPV-2c. Faecal samples were obtained from 30 dogs that were CPV antigen-positive. The DNA was isolated from the faecal samples and PCR-amplified using the two sets of primers, and genotyped by HRM curve analysis. The PCR-HRM assay was able to distinguish single nucleotide polymorphisms between CPV-2a, CPV-2b and CPV-2c using CPV-426F/426R. CPV-2a was distinguished from CPV-2b and CPV-2c by differences in the melting temperature. CPV-2b and CPV-2c could be distinguished based on the shape of the melting curve after generating heteroduplexes using a CPV-2b reference sample. The vaccine strains of CPV-2 were identified using CPV-87F/87R. Conventional methods for genotyping CPV strains are labor intensive, expensive or time consuming; the present PCR-based HRM assay might be an attractive alternative. Copyright © 2014 Elsevier Ltd. All rights reserved.

Chest computed tomography scores are predictive of survival in patients with cystic fibrosis awaiting lung transplantation

DEFF Research Database (Denmark)

Loeve, Martine; Hop, Wim C. J.; de Bruijne, Marleen

2012-01-01

Rationale: Up to a third of cystic fibrosis (CF) patients awaiting lung transplantation (LTX) die while waiting. Inclusion of computed tomography (CT) scores may improve survival prediction models such as the lung allocation score (LAS). Objectives: This study investigated the association between...... CT and survival in CF patients screened for LTX. Methods: Clinical data and chest CTs of 411 CF patients screened for LTX between 1990 and 2005 were collected from 17 centers. CTs were scored with the Severe Advanced Lung Disease (SALD) 4-category scoring system, including the components "infection....../inflammation" (INF), air trapping/hypoperfusion (AT), normal/hyperperfusion (NOR) and bulla/cysts (BUL). The volume of each component was computed using semi-automated software. Survival analysis included Kaplan-Meier curves, and Cox-regression models. Measurements and main results: 366 (186 males) out of 411...

Titration Curves: Fact and Fiction.

Science.gov (United States)

Chamberlain, John

1997-01-01

Discusses ways in which datalogging equipment can enable titration curves to be measured accurately and how computing power can be used to predict the shape of curves. Highlights include sources of error, use of spreadsheets to generate titration curves, titration of a weak acid with a strong alkali, dibasic acids, weak acid and weak base, and…

Study on cell survival, induction of apoptosis and micronucleus formation in SCL-II and RTiV3 cells after exposure to the Auger electron emitter Tc-99m

International Nuclear Information System (INIS)

Kadenbach, K.; Kriehuber, R.; Weiss, D.G.

2003-01-01

Full text: Cell survival, induction of apoptosis and micronucleus (MN) formation have been investigated in the human squamous cell carcinoma cell line SCL-II and in the rat tracheal cell line RTiV3 after exposure to the Auger electron emitter Tc-99m. Cells were either acutely gamma(Co-60)-irradiated (0.78 Gy/min) or exposed to Tc-99m-Pertechnetate (25-300 MBq/20ml) for 24 h under cell culture conditions and assayed for cell survival (Colony-forming assay), micronucleus formation (Cytochalasin B assay) and the frequency of apoptotic cells (Fluorescence microscopy). Analytical dosimetrical models have been applied to derive the absorbed dose corresponding to the accumulated decays of Tc-99m. Absorbed doses up to 1.3 Gy could be achieved after Tc-99m exposure leading to no significant cell killing in this dose range except at one dose point (0.25 Gy) in SCL-II cells. MN formation was consistently lower when compared to Co-60 irradiated cells and showed a linear dose-response. The apoptotic response in SCL-II cells after Tc-99m exposure was described best by a 3rd order polynomial and increased apoptosis induction could be observed at much lower doses (0.25 Gy) in comparison to the reference radiation (0.8 Gy). The relative biological effectiveness (RBE) has been determined for MN formation and apoptosis induction and was found to be in the range of 0.1- 1.3 for both investigated biological endpoints, depending on which mathematical model for describing the dose-effect curve was used. Up-take experiments revealed an activity concentration ratio cells vs. medium of 1.2 after 16 h up to 24 h of exposure. No increased biological effectiveness of Tc-99m applied as Sodium-Pertechnetate could be observed in the investigated cell lines in comparison to gamma-irradiation. Induction of apoptosis is slightly increased after Tc-99m exposure in SCL-II cells and it has to be further evaluated, if this is due to the emitted Auger-component. A passive up-take mechanism of Tc-99m is

Inverse Diffusion Curves Using Shape Optimization.

Science.gov (United States)

Zhao, Shuang; Durand, Fredo; Zheng, Changxi

2018-07-01

The inverse diffusion curve problem focuses on automatic creation of diffusion curve images that resemble user provided color fields. This problem is challenging since the 1D curves have a nonlinear and global impact on resulting color fields via a partial differential equation (PDE). We introduce a new approach complementary to previous methods by optimizing curve geometry. In particular, we propose a novel iterative algorithm based on the theory of shape derivatives. The resulting diffusion curves are clean and well-shaped, and the final image closely approximates the input. Our method provides a user-controlled parameter to regularize curve complexity, and generalizes to handle input color fields represented in a variety of formats.

A urine midmolecule osteocalcin assay shows higher discriminatory power than a serum midmolecule osteocalcin assay during short-term alendronate treatment of osteoporotic patients.

Science.gov (United States)

Srivastava, A K; Mohan, S; Singer, F R; Baylink, D J

2002-07-01

We isolated and characterized a peptide fragment corresponding to amino acid sequence 14-28 of human osteocalcin in urine from Paget's disease, and developed a polyclonal antibody reactive to this peptide in urine. We used this antibody to measure urinary fragments of osteocalcin and compared to efficacy of the urinary osteocalcin assay with a serum osteocalcin (sOC) assay (ELISA-Osteo, Cis-Bio International) to monitor the short-term changes in bone turnover in response to alendronate treatment. The synthetic peptide-based urinary osteocalcin (uOC) radioimmunoassay (RIA) showed an analytical sensitivity of 6.25 ng/mL, standard curve range of 3.12-400 ng/mL, and mean intra- (n = 20) and interassay (n = 30) coefficient of variation (CV) of sALP) (Alkphose-B, Metra Biosystems) in serum samples. The percent change data obtained between baseline and 30 days (n = 18) posttreatment suggested a rapid decline in uOC concentration (-27%, p sALP (-3.4%, p = 0.689), two specific markers of bone formation. As expected, due to the coupling of bone formation and bone resorption, the concentration of all markers showed a 30%-45% decline compared with baseline values after 90 days (n = 16) of treatment. Correlation of markers after a 30 day treatment with alendronate revealed a higher correlation (r = 0.61, p sALP (r = -0.14, p = 0.295) with uNTx. Similarly, correlation coefficients with r values between 0.48 and 0.55 (p < 0.05) were observed between uOC, sNTx, and sCTx, whereas no significant correlation was observed between sOC and sNTx or sCTx. These results provide indirect evidence that fragments measured by the urine assay probably originated from bone resorption, and suggest that the uOC assay could be used to assess short-term changes in bone metabolism with regard to osteocalcin.

Survival and photoreactivability of ultraviolet-irradiated cultured fish cells (CAF-MM1)

International Nuclear Information System (INIS)

Mano, Y.; Mitani, H.; Etoh, H.; Egami, N.

1980-01-01

The sensitivity to ultraviolet light (uv) and photoreactivating ability of cultured fish clone cells (CAF-MM1) were investigated. Dose-survival relationship curves were obtained using the colony-forming technique at various postirradiation temperatures (33, 26, and 20 0 C). At 26 0 C the values of D 0 , D/sub q/, and the extrapolation number (n) were 1.74 J/m 2 , 2.62 J/m 2 , and 4.5, respectively; no marked differences in these values were found among different temperatures. Visible light illumination after uv irradiation produced a marked increase in survival. No photoreactivation effects were observed beyond about 30 h. Caffeine increased uv sensitivity of the CAF-MM1 cells, and from the results it is suggested that the cells have some caffeine-sensitive dark repair mechanisms

Retrograde curves of solidus and solubility

International Nuclear Information System (INIS)

Vasil'ev, M.V.

1979-01-01

The investigation was concerned with the constitutional diagrams of the eutectic type with ''retrograde solidus'' and ''retrograde solubility curve'' which must be considered as diagrams with degenerate monotectic transformation. The solidus and the solubility curves form a retrograde curve with a common retrograde point representing the solubility maximum. The two branches of the Aetrograde curve can be described with the aid of two similar equations. Presented are corresponding equations for the Cd-Zn system and shown is the possibility of predicting the run of the solubility curve

EBV induces persistent NF-κB activation and contributes to survival of EBV-positive neoplastic T- or NK-cells.

Directory of Open Access Journals (Sweden)

Honami Takada

Full Text Available Epstein-Barr virus (EBV has been detected in several T- and NK-cell neoplasms such as extranodal NK/T-cell lymphoma nasal type, aggressive NK-cell leukemia, EBV-positive peripheral T-cell lymphoma, systemic EBV-positive T-cell lymphoma of childhood, and chronic active EBV infection (CAEBV. However, how this virus contributes to lymphomagenesis in T or NK cells remains largely unknown. Here, we examined NF-κB activation in EBV-positive T or NK cell lines, SNT8, SNT15, SNT16, SNK6, and primary EBV-positive and clonally proliferating T/NK cells obtained from the peripheral blood of patients with CAEBV. Western blotting, electrophoretic mobility shift assays, and immunofluorescent staining revealed persistent NF-κB activation in EBV-infected cell lines and primary cells from patients. Furthermore, we investigated the role of EBV in infected T cells. We performed an in vitro infection assay using MOLT4 cells infected with EBV. The infection directly induced NF-κB activation, promoted survival, and inhibited etoposide-induced apoptosis in MOLT4 cells. The luciferase assay suggested that LMP1 mediated NF-κB activation in MOLT4 cells. IMD-0354, a specific inhibitor of NF-κB that suppresses NF-κB activation in cell lines, inhibited cell survival and induced apoptosis. These results indicate that EBV induces NF-κB-mediated survival signals in T and NK cells, and therefore, may contribute to the lymphomagenesis of these cells.

The optimal condition of performing MTT assay for the determination of radiation sensitivity

International Nuclear Information System (INIS)

Hong, Semie; Kim, Il Han

2001-01-01

The measurement of radiation survival using a clonogenic assay, the established standard, can be difficult and time consuming. In this study, We have used the MTT assay, based on the reduction of a tetrazolium salt to a purple formazan precipitate by living cells, as a substitution for clonogenic assay and have examined the optimal condition for performing this assay in determination of radiation sensitivity. Four human cancer cell lines - PCI-1, SNU-1066, NCI-H63O and RKO cells have been used. For each cell line, a clonogenic assay and a MTT assay using Premix WST-1 solution, which is one of the tetrazolium salts and does not require washing or solubilization of the precipitate were carried out after irradiation of 0, 2, 4, 6, 8, 10 Gy, For clonogenic assay, cells in 25 cm 2 flasks were irradiated after overnight incubation and the resultant colonies containing more than 50 cells were scored after culturing the cells for 10-14 days, For MTT assay, the relationship between absorbance and cell number, optimal seeding cell number, and optimal timing of assay was determined. Then, MTT assay was performed when the irradiated cells had regained exponential growth or when the non-irradiated cells had undergone four or more doubling times. There was minimal variation in the values gained from these two methods with the standard deviation generally less than 5%, and there were no statistically significant differences between two methods according to t-test in low radiation dose (below 6 Gy). The regression analyses showed high linear correlation with the R 2 value of 0.975-0.992 between data from the two different methods. The optimal cell numbers for MTT assay were found to be dependent on plating efficiency of used cell line. Less than 300 cells/well were appropriate for cells with high plating efficiency (more than 30%). For cells with low plating efficiency (less than 30%), 500 cells/well or more were appropriate for assay. The optimal time for MTT assay was alter 6

[Customized and non-customized French intrauterine growth curves. II - Comparison with existing curves and benefits of customization].

Science.gov (United States)

Ego, A; Prunet, C; Blondel, B; Kaminski, M; Goffinet, F; Zeitlin, J

2016-02-01

Our aim is to compare the new French EPOPé intrauterine growth curves, developed to address the guidelines 2013 of the French College of Obstetricians and Gynecologists, with reference curves currently used in France, and to evaluate the consequences of their adjustment for fetal sex and maternal characteristics. Eight intrauterine and birthweight curves, used in France were compared to the EPOPé curves using data from the French Perinatal Survey 2010. The influence of adjustment on the rate of SGA births and the characteristics of these births was analysed. Due to their birthweight values and distribution, the selected intrauterine curves are less suitable for births in France than the new curves. Birthweight curves led to low rates of SGA births from 4.3 to 8.5% compared to 10.0% with the EPOPé curves. The adjustment for maternal and fetal characteristics avoids the over-representation of girls among SGA births, and reclassifies 4% of births. Among births reclassified as SGA, the frequency of medical and obstetrical risk factors for growth restriction, smoking (≥10 cigarettes/day), and neonatal transfer is higher than among non-SGA births (P<0.01). The EPOPé curves are more suitable for French births than currently used curves, and their adjustment improves the identification of mothers and babies at risk of growth restriction and poor perinatal outcomes. Copyright © 2015 Elsevier Masson SAS. All rights reserved.

Concepts, problems and the role of modifying agents in the relationship between recovery of cells' survival ability and mechanisms of repair of radiation lesions

International Nuclear Information System (INIS)

Orr, J.S.

1984-01-01

The two strands of the problem are the shapes and changes with time of cell survival curves on the one hand and the responses of cell constituents to radiation on the other. Evidence of correlations between results of studies of these two types of phenomena under the influence of a wide range of modifying agents is required to establish mechanisms. Recovery may be defined as referring to the whole cell, while repair should be regarded as a process carried out by one substance on another. The degrees of usefulness and possible deficiencies of a multi-hit/target model and a repair model for explaining cell survival curves and cell recovery are compared in a range of circumstances. A fully satisfactory model is not yet available. (author)

Extended analysis of cooling curves

International Nuclear Information System (INIS)

Djurdjevic, M.B.; Kierkus, W.T.; Liliac, R.E.; Sokolowski, J.H.

2002-01-01

Thermal Analysis (TA) is the measurement of changes in a physical property of a material that is heated through a phase transformation temperature range. The temperature changes in the material are recorded as a function of the heating or cooling time in such a manner that allows for the detection of phase transformations. In order to increase accuracy, characteristic points on the cooling curve have been identified using the first derivative curve plotted versus time. In this paper, an alternative approach to the analysis of the cooling curve has been proposed. The first derivative curve has been plotted versus temperature and all characteristic points have been identified with the same accuracy achieved using the traditional method. The new cooling curve analysis also enables the Dendrite Coherency Point (DCP) to be detected using only one thermocouple. (author)

Detection of Hypoxia in Human Brain Tumor Xenografts Using a Modified Comet Assay

Directory of Open Access Journals (Sweden)

Jingli Wang

2003-07-01

Full Text Available We used the standard comet assay successfully to generate in vitro dose-response curves under oxic and hypoxic conditions. We then made mixtures of cells that had been irradiated with 3 and 9 Gy of X-rays to simulate two subpopulations in a tumor, but efforts to accurately detect and quantify the subpopulations using the standard comet assay were unsuccessful. Therefore, we investigated a modified comet assay to determine whether it could be used for measuring hypoxia in our model systems. U251 MG cells were grown as subcutaneous tumors in athymic mice; U251 MG and U87 MG cells were grown as intracerebral (i.c. tumors in athymic rats. Animals were injected with RSU 1069, irradiated, and euthanized. Tumors and normal brains were removed, and the cells were analyzed using a modified comet assay. Differences in comet tail moment distributions between tumor and contralateral normal brain, using tail moments at either the 25th or 50th percentile in each distribution, were taken as measures of the degree of tumor hypoxia. For U251 MG tumors, there was a positive relationship between tumor size and the degree of hypoxia, whereas preliminary data from U87 MG i.c. tumors showed less hypoxia and no apparent relationship between tumor size and hypoxia.

Predictors of adalimumab drug survival in psoriasis differ by reason for discontinuation: long-term results from the Bio-CAPTURE registry.

Science.gov (United States)

van den Reek, J M P A; Tummers, M; Zweegers, J; Seyger, M M B; van Lümig, P P M; Driessen, R J B; van de Kerkhof, P C M; Kievit, W; de Jong, E M G J

2015-03-01

Drug survival is an indicator for treatment success; insight in predictors associated with drug survival is important. To analyse the long-term drug survival for adalimumab in patients with psoriasis treated in daily practice and (II) to identify predictors of prolonged drug survival for adalimumab split for different reasons of discontinuation. Data were extracted from a prospective psoriasis cohort and analysed using Kaplan-Meier survival curves split for reasons of discontinuation. Baseline predictors associated with longer drug survival were identified using multivariate Cox-regression analysis. One hundred and sixteen patients were included with a total of 208 patient-years. Overall drug survival was 76% after 1 year and 52% after 4.5 years. In patients who stopped due to ineffectiveness, longer drug survival was associated with the absence of specific comorbidities (P = 0.03). In patients who stopped due to side-effects, longer drug survival was associated with male gender (P = 0.02). Predictors of adalimumab drug survival in psoriasis differ by reason for discontinuation. Strong, specific predictors can lead to patient-tailored treatment. © 2014 European Academy of Dermatology and Venereology.

Performance of the new automated Abbott RealTime MTB assay for rapid detection of Mycobacterium tuberculosis complex in respiratory specimens.

Science.gov (United States)

Chen, J H K; She, K K K; Kwong, T-C; Wong, O-Y; Siu, G K H; Leung, C-C; Chang, K-C; Tam, C-M; Ho, P-L; Cheng, V C C; Yuen, K-Y; Yam, W-C

2015-09-01

The automated high-throughput Abbott RealTime MTB real-time PCR assay has been recently launched for Mycobacterium tuberculosis complex (MTBC) clinical diagnosis. This study would like to evaluate its performance. We first compared its diagnostic performance with the Roche Cobas TaqMan MTB assay on 214 clinical respiratory specimens. Prospective analysis of a total 520 specimens was then performed to further evaluate the Abbott assay. The Abbott assay showed a lower limit of detection at 22.5 AFB/ml, which was more sensitive than the Cobas assay (167.5 AFB/ml). The two assays demonstrated a significant difference in diagnostic performance (McNemar's test; P = 0.0034), in which the Abbott assay presented significantly higher area under curve (AUC) than the Cobas assay (1.000 vs 0.880; P = 0.0002). The Abbott assay demonstrated extremely low PCR inhibition on clinical respiratory specimens. The automated Abbott assay required only very short manual handling time (0.5 h), which could help to improve the laboratory management. In the prospective analysis, the overall estimates for sensitivity and specificity of the Abbott assay were both 100 % among smear-positive specimens, whereas the smear-negative specimens were 96.7 and 96.1 %, respectively. No cross-reactivity with non-tuberculosis mycobacterial species was observed. The superiority in sensitivity of the Abbott assay for detecting MTBC in smear-negative specimens could further minimize the risk in MTBC false-negative detection. The new Abbott RealTime MTB assay has good diagnostic performance which can be a useful diagnostic tool for rapid MTBC detection in clinical laboratories.

Tempo curves considered harmful

NARCIS (Netherlands)

Desain, P.; Honing, H.

1993-01-01

In the literature of musicology, computer music research and the psychology of music, timing or tempo measurements are mostly presented in the form of continuous curves. The notion of these tempo curves is dangerous, despite its widespread use, because it lulls its users into the false impression

SU-E-T-253: Open-Source Automatic Software for Quantifying Biological Assays of Radiation Effects

International Nuclear Information System (INIS)

Detappe, A; Korideck, H; Makrigiorgos, G; Berbeco, R

2014-01-01

Purpose: Clonogenic cell survival is a common assay for quantifying the effect of drugs and radiation. Manual counting of surviving colonies can take 30–90seconds per plate, a major limitation for large studies. Currently available automatic counting tools are not easily modified for radiation oncology research. Our goal is to provide an open-source toolkit for precise, accurate and fast analysis of biological assays in radiation oncology. Methods: As an example analysis, we used HeLa cells incubated with gadolinium nanoparticles prior to irradiation. After treatment, the cells are grown for 14days to allow for colony formation. To analyze the colony growth, we capture images of each dish for archiving and automatic computer-based analysis. A FujifilmX20 camera is placed at the top of a box setup, 20cm above the sample, which is backlit by a LED lamp placed at the bottom of the box. We use a Gaussian filter (width=1.3mm) and color threshold (19–255). The minimum size for a colony to be counted is 1mm. For this example, 20 dishes with a large range of colonies were analyzed. Each dish was counted 3 times manually by 3 different users and then compared to our counter. Results: Automatic counting of cell colonies takes an average of 7seconds, enabling the analysis process to be accelerated 4–12 times. The average precision of the automatic counter was 1.7%. The Student t-test demonstrated the non-significant differences between the two counting methods (p=0.64). The ICC demonstrated the reliability of each method with ICC>0.999 (automatic) and ICC=0.95 (manual). Conclusion: We developed an open-source automatic toolkit for the analysis of biological assays in radiation oncology and demonstrated the accuracy, precision and effort savings for clonogenic cell survival quantification. This toolkit is currently being used in two laboratories for routine experimental analysis and will be made freely available on our departmental website

Molecular surveillance of true nontypeable Haemophilus influenzae: an evaluation of PCR screening assays.

Science.gov (United States)

Binks, Michael J; Temple, Beth; Kirkham, Lea-Ann; Wiertsema, Selma P; Dunne, Eileen M; Richmond, Peter C; Marsh, Robyn L; Leach, Amanda J; Smith-Vaughan, Heidi C

2012-01-01

Unambiguous identification of nontypeable Haemophilus influenzae (NTHi) is not possible by conventional microbiology. Molecular characterisation of phenotypically defined NTHi isolates suggests that up to 40% are Haemophilus haemolyticus (Hh); however, the genetic similarity of NTHi and Hh limits the power of simple molecular techniques such as PCR for species discrimination. Here we assess the ability of previously published and novel PCR-based assays to identify true NTHi. Sixty phenotypic NTHi isolates, classified by a dual 16S rRNA gene PCR algorithm as NTHi (n = 22), Hh (n = 27) or equivocal (n = 11), were further characterised by sequencing of the 16S rRNA and recA genes then interrogated by PCR-based assays targeting the omp P2, omp P6, lgtC, hpd, 16S rRNA, fucK and iga genes. The sequencing data and PCR results were used to define NTHi for this study. Two hpd real time PCR assays (hpd#1 and hpd#3) and the conventional iga PCR assay were equally efficient at differentiating study-defined NTHi from Hh, each with a receiver operator characteristic curve area of 0.90 [0.83; 0.98]. The hpd#1 and hpd#3 assays were completely specific against a panel of common respiratory bacteria, unlike the iga PCR, and the hpd#3 assay was able to detect below 10 copies per reaction. Our data suggest an evolutionary continuum between NTHi and Hh and therefore no single gene target could completely differentiate NTHi from Hh. The hpd#3 real time PCR assay proved to be the superior method for discrimination of NTHi from closely related Haemophilus species with the added potential for quantification of H. influenzae directly from specimens. We suggest the hpd#3 assay would be suitable for routine NTHi surveillance and to assess the impact of antibiotics and vaccines, on H. influenzae carriage rates, carriage density, and disease.

Molecular surveillance of true nontypeable Haemophilus influenzae: an evaluation of PCR screening assays.

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Michael J Binks

Full Text Available BACKGROUND: Unambiguous identification of nontypeable Haemophilus influenzae (NTHi is not possible by conventional microbiology. Molecular characterisation of phenotypically defined NTHi isolates suggests that up to 40% are Haemophilus haemolyticus (Hh; however, the genetic similarity of NTHi and Hh limits the power of simple molecular techniques such as PCR for species discrimination. METHODOLOGY/PRINCIPAL FINDINGS: Here we assess the ability of previously published and novel PCR-based assays to identify true NTHi. Sixty phenotypic NTHi isolates, classified by a dual 16S rRNA gene PCR algorithm as NTHi (n = 22, Hh (n = 27 or equivocal (n = 11, were further characterised by sequencing of the 16S rRNA and recA genes then interrogated by PCR-based assays targeting the omp P2, omp P6, lgtC, hpd, 16S rRNA, fucK and iga genes. The sequencing data and PCR results were used to define NTHi for this study. Two hpd real time PCR assays (hpd#1 and hpd#3 and the conventional iga PCR assay were equally efficient at differentiating study-defined NTHi from Hh, each with a receiver operator characteristic curve area of 0.90 [0.83; 0.98]. The hpd#1 and hpd#3 assays were completely specific against a panel of common respiratory bacteria, unlike the iga PCR, and the hpd#3 assay was able to detect below 10 copies per reaction. CONCLUSIONS/SIGNIFICANCE: Our data suggest an evolutionary continuum between NTHi and Hh and therefore no single gene target could completely differentiate NTHi from Hh. The hpd#3 real time PCR assay proved to be the superior method for discrimination of NTHi from closely related Haemophilus species with the added potential for quantification of H. influenzae directly from specimens. We suggest the hpd#3 assay would be suitable for routine NTHi surveillance and to assess the impact of antibiotics and vaccines, on H. influenzae carriage rates, carriage density, and disease.

Biotin radioligand assay with an 125I-labeled biotin derivative, avidin, and avidin double-antibody reagents

International Nuclear Information System (INIS)

Livaniou, E.; Evangelatos, G.P.; Ithakissios, D.S.

1987-01-01

We describe a new radioligand assay for determining biotin in biological fluids by using a mixture of N-[beta-(4-OH-3-125I-phenyl)ethyl]- and N-[beta-(4-OH-3,5-di-125I-phenyl)ethyl]biotinamides as radiotracer, avidin as a binding protein, and an avidin double-antibody as a separation reagent. The radiotracer is synthesized by coupling (at pH 8.5, 20-22 degrees C, 90 min) N-hydroxysuccinimidobiotin to radioiodinated tyramine. The assay curve is linear and the assay itself is sensitive (less than 10 ng/L), reproducible (intra- and interassay CVs 4.1% and 7.0%, respectively), and allows the simultaneous handling of more than 100 samples in less than 4 h. Serum samples from apparently normal subjects contained 100-840 ng of biotin per liter (mean 340 ng/L). Pregnant women had low concentrations of biotin (100-300 ng/L) in their serum. Patients undergoing chronic hemodialysis treatment showed high concentrations (0.5-3.0 micrograms/L), which may be ascribable to the inability of avidin, which was used as the assay binding protein, to distinguish biotin from biotinyl derivatives with an intact ureido ring

Rapid screening for targeted genetic variants via high-resolution melting curve analysis.

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Chambliss, Allison B; Resnick, Molly; Petrides, Athena K; Clarke, William A; Marzinke, Mark A

2017-03-01

Current methods for the detection of single nucleotide polymorphisms (SNPs) associated with aberrant drug-metabolizing enzyme function are hindered by long turnaround times and specialized techniques and instrumentation. In this study, we describe the development and validation of a high-resolution melting (HRM) curve assay for the rapid screening of variant genotypes for targeted genetic polymorphisms in the cytochrome P450 enzymes CYP2C9, CYP2C19, and CYP3A5. Sequence-specific primers were custom-designed to flank nine SNPs within the genetic regions of aforementioned drug metabolizing enzymes. PCR amplification was performed followed by amplicon denaturation by precise temperature ramping in order to distinguish genotypes by melting temperature (Tm). A standardized software algorithm was used to assign amplicons as 'reference' or 'variant' as compared to duplicate reference sequence DNA controls for each SNP. Intra-assay (n=5) precision of Tms for all SNPs was ≤0.19%, while inter-assay (n=20) precision ranged from 0.04% to 0.21%. When compared to a reference method of Sanger sequencing, the HRM assay produced no false negative results, and overcall frequency ranged from 0% to 26%, depending on the SNP. Furthermore, HRM genotyping displayed accuracy over input DNA concentrations ranging from 10 to 200 ng/μL. The presented assay provides a rapid method for the screening for genetic variants in targeted CYP450 regions with a result of 'reference' or 'variant' available within 2 h from receipt of extracted DNA. The method can serve as a screening approach to rapidly identify individuals with variant sequences who should be further investigated by reflexed confirmatory testing for aberrant cytochrome P450 enzymatic activity. Rapid knowledge of variant status may aid in the avoidance of adverse clinical events by allowing for dosing of normal metabolizer patients immediately while identifying the need to wait for confirmatory testing in those patients who are

Radiosensitivity evaluation of human tumor cell lines by detecting 4977 bp deletion in mitochondrial DNA and comet assay

International Nuclear Information System (INIS)

Chu Liping; Liu Qiang; Wang Qin; Li Jin; Yue Jingyin; Mu Chuanjie; Fan Feiyue

2008-01-01

Objective: To explore the feasibility of determining radiosensitivity of human tumor cell lines in vitro using the assay of mtDNA 4977 bp deletion and comet assay. Methods: Three human tumor cell lines were selected in this study, HepG 2 , EC-9706 and MCF-7. The surviving fraction(SF), the ratio of mtDNA 4977 bp deletion and DNA damage were detected by MTY assay, nested PCR technique and comet assay, respectively. Results: The results of MTT assay showed that the radiosensitivity of HepG 2 and EC-9706 was higher than that of MCF-7. The ratio of mtDNA 4977 bp deletion of HepG 2 and EC-9706 was higher significantly than that of MCF-7 (P 2 and EC-9706 was higher than that of MCF-7. The difference of radiosensitivity among these three tumor cell lines was significant after 8 Gy γ-ray irradiation. Conclusions: Combination of many biological parameter is helpful to evaluate the radiosensitivity of tumor cells more accurately. (authors)

Huang's three-step maneuver shortens the learning curve of laparoscopic spleen-preserving splenic hilar lymphadenectomy.

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Huang, Chang-Ming; Huang, Ze-Ning; Zheng, Chao-Hui; Li, Ping; Xie, Jian-Wei; Wang, Jia-Bin; Lin, Jian-Xian; Jun, Lu; Chen, Qi-Yue; Cao, Long-Long; Lin, Mi; Tu, Ru-Hong

2017-12-01

The goal of this study was to investigate the difference between the learning curves of different maneuvers in laparoscopic spleen-preserving splenic hilar lymphadenectomy for advanced upper gastric cancer. From January 2010 to April 2014, 53 consecutive patients who underwent laparoscopic spleen-preserving splenic hilar lymphadenectomy via the traditional-step maneuver (group A) and 53 consecutive patients via Huang's three-step maneuver (group B) were retrospectively analyzed. No significant difference in patient characteristics were found between the two groups. The learning curves of groups A and B were divided into phase 1 (1-43 cases and 1-30 cases, respectively) and phase 2 (44-53 cases and 31-53 cases, respectively). Compared with group A, the dissection time, bleeding loss and vascular injury were significantly decreased in group B. No significant differences in short-term outcomes were found between the two maneuvers. The multivariate analysis indicated that the body mass index, short gastric vessels, splenic artery type and maneuver were significantly associated with the dissection time in group B. No significant difference in the survival curve was found between the maneuvers. The learning curve of Huang's three-step maneuver was shorter than that of the traditional-step maneuver, and the former represents an ideal maneuver for laparoscopic spleen-preserving splenic hilar lymphadenectomy.To shorten the learning curve at the beginning of laparoscopic spleen-preserving splenic hilar lymphadenectomy, beginners should beneficially use Huang's three-step maneuver and select patients with advanced upper gastric cancer with a body mass index of less than 25 kg/m 2 and the concentrated type of splenic artery. Copyright © 2017. Published by Elsevier Ltd.

A simple and convenient microtiter plate assay for the detection of bactericidal antibodies to Vibrio cholerae O1 and Vibrio cholerae O139.

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Boutonnier, Alain; Dassy, Bruno; Duménil, Rémy; Guénolé, Alain; Ratsitorahina, Maherisoa; Migliani, René; Fournier, Jean-Michel

2003-12-01

It is believed that the correlate of protection for cholera can be determined by the serum vibriocidal assay. The currently available vibriocidal assays, based on the conventional agar plating technique, are labor intensive. We developed a simple and convenient microtiter plate assay for the detection of vibriocidal antibodies that is equally as efficient for Vibrio cholerae O1 and for V. cholerae O139. The addition of succinate and neotetrazolium made it possible to measure the growth of surviving bacterial target cells by monitoring a color change. We evaluated assay parameters (target strains, growth of target cells, complement source and concentration) that may affect the reproducibility of the method for V. cholerae O139. The results obtained with the microtiter plate assay were uniformly similar to those obtained with the conventional agar plating assay, when testing both the Inaba and Ogawa serotypes of V. cholerae O1. The microtiter plate assay was also convenient for measuring the activity of animal sera and mouse monoclonal antibodies.

Image scaling curve generation

NARCIS (Netherlands)

2012-01-01

The present invention relates to a method of generating an image scaling curve, where local saliency is detected in a received image. The detected local saliency is then accumulated in the first direction. A final scaling curve is derived from the detected local saliency and the image is then

Image scaling curve generation.

NARCIS (Netherlands)

2011-01-01

The present invention relates to a method of generating an image scaling curve, where local saliency is detected in a received image. The detected local saliency is then accumulated in the first direction. A final scaling curve is derived from the detected local saliency and the image is then

Identification of antifungal compounds active against Candida albicans using an improved high-throughput Caenorhabditis elegans assay.

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Ikechukwu Okoli

2009-09-01

Full Text Available Candida albicans, the most common human pathogenic fungus, can establish a persistent lethal infection in the intestine of the microscopic nematode Caenorhabditis elegans. The C. elegans-C. albicans infection model was previously adapted to screen for antifungal compounds. Modifications to this screen have been made to facilitate a high-throughput assay including co-inoculation of nematodes with C. albicans and instrumentation allowing precise dispensing of worms into assay wells, eliminating two labor-intensive steps. This high-throughput method was utilized to screen a library of 3,228 compounds represented by 1,948 bioactive compounds and 1,280 small molecules derived via diversity-oriented synthesis. Nineteen compounds were identified that conferred an increase in C. elegans survival, including most known antifungal compounds within the chemical library. In addition to seven clinically used antifungal compounds, twelve compounds were identified which are not primarily used as antifungal agents, including three immunosuppressive drugs. This assay also allowed the assessment of the relative minimal inhibitory concentration, the effective concentration in vivo, and the toxicity of the compound in a single assay.

Microbiological assay for the analysis of certain macrolides in pharmaceutical dosage forms.

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Mahmoudi, A; Fourar, R E-A; Boukhechem, M S; Zarkout, S

2015-08-01

Clarithromycin (CLA) and roxithromycin (ROX) are macrolide antibiotics with an expanded spectrum of activity that are commercially available as tablets. A microbiological assay, applying the cylinder-plate method and using a strain of Micrococcus luteus ATCC 9341 as test organism, has been used and validated for the quantification of two macrolide drugs; CLA and ROX in pure and pharmaceutical formulations. The validation of the proposed method was carried out for linearity, precision, accuracy and specificity. The linear dynamic ranges were from 0.1 to 0.5μg/mL for both compounds. Logarithmic calibration curve was obtained for each macrolide (r>0.989) with statistically equal slopes varying from 3.275 to 4.038, and a percentage relative standard deviation in the range of 0.24-0.92%. Moreover, the method was applied successfully for the assay of the studied drugs in pharmaceutical tablet dosage forms. Recovery from standard addition experiments in commercial products was 94.71-96.91% regarding clarithromycin and 93.94-98.12% regarding roxithromycin, with a precision (%RSD) 1.32-2.11%. Accordingly, this microbiological assay can be used for routine quality control analysis of titled drugs in tablet formulations. Copyright © 2015 Elsevier B.V. All rights reserved.

Selection of non-destructive assay methods: Neutron counting or calorimetric assay?

International Nuclear Information System (INIS)

Cremers, T.L.; Wachter, J.R.

1994-01-01

The transition of DOE facilities from production to D ampersand D has lead to more measurements of product, waste, scrap, and other less attractive materials. Some of these materials are difficult to analyze by either neutron counting or calorimetric assay. To determine the most efficacious analysis method, variety of materials, impure salts and hydrofluorination residues have been assayed by both calorimetric assay and neutron counting. New data will be presented together with a review of published data. The precision and accuracy of these measurements are compared to chemistry values and are reported. The contribution of the gamma ray isotopic determination measurement to the overall error of the calorimetric assay or neutron assay is examined and discussed. Other factors affecting selection of the most appropriate non-destructive assay method are listed and considered

A cell-based high-throughput screening assay for radiation susceptibility using automated cell counting

International Nuclear Information System (INIS)

Hodzic, Jasmina; Dingjan, Ilse; Maas, Mariëlle JP; Meulen-Muileman, Ida H van der; Menezes, Renee X de; Heukelom, Stan; Verheij, Marcel; Gerritsen, Winald R; Geldof, Albert A; Triest, Baukelien van; Beusechem, Victor W van

2015-01-01

Radiotherapy is one of the mainstays in the treatment for cancer, but its success can be limited due to inherent or acquired resistance. Mechanisms underlying radioresistance in various cancers are poorly understood and available radiosensitizers have shown only modest clinical benefit. There is thus a need to identify new targets and drugs for more effective sensitization of cancer cells to irradiation. Compound and RNA interference high-throughput screening technologies allow comprehensive enterprises to identify new agents and targets for radiosensitization. However, the gold standard assay to investigate radiosensitivity of cancer cells in vitro, the colony formation assay (CFA), is unsuitable for high-throughput screening. We developed a new high-throughput screening method for determining radiation susceptibility. Fast and uniform irradiation of batches up to 30 microplates was achieved using a Perspex container and a clinically employed linear accelerator. The readout was done by automated counting of fluorescently stained nuclei using the Acumen eX3 laser scanning cytometer. Assay performance was compared to that of the CFA and the CellTiter-Blue homogeneous uniform-well cell viability assay. The assay was validated in a whole-genome siRNA library screening setting using PC-3 prostate cancer cells. On 4 different cancer cell lines, the automated cell counting assay produced radiation dose response curves that followed a linear-quadratic equation and that exhibited a better correlation to the results of the CFA than did the cell viability assay. Moreover, the cell counting assay could be used to detect radiosensitization by silencing DNA-PKcs or by adding caffeine. In a high-throughput screening setting, using 4 Gy irradiated and control PC-3 cells, the effects of DNA-PKcs siRNA and non-targeting control siRNA could be clearly discriminated. We developed a simple assay for radiation susceptibility that can be used for high-throughput screening. This will aid

Rural AIDS Diagnoses in Florida: Changing Demographics and Factors Associated With Survival

Science.gov (United States)

Trepka, Mary Jo; Niyonsenga, Theophile; Maddox, Lorene M.; Lieb, Spencer

2012-01-01

Purpose To compare demographic characteristics and predictors of survival of rural residents diagnosed with acquired immunodeficiency syndrome (AIDS) with those of urban residents. Methods Florida surveillance data for people diagnosed with AIDS during 1993–2007 were merged with 2000 Census data using ZIP code tabulation areas (ZCTA). Rural status was classified based on the ZCTA’s rural-urban commuting area classification. Survival rates were compared between rural and urban areas using survival curves and Cox proportional hazards models controlling for demographic, clinical, and area-level socioeconomic and health care access factors. Findings Of the 73,590 people diagnosed with AIDS, 1,991 (2.7%) resided in rural areas. People in the most recent rural cohorts were more likely than those in earlier cohorts to be female, non-Hispanic black, older, and have a reported transmission mode of heterosexual sex. There were no statistically significant differences in the 3-, 5-, or 10-year survival rates between rural and urban residents. Older age at the time of diagnosis, diagnosis during the 1993–1995 period, other/unknown transmission mode, and lower CD4 count/percent categories were associated with lower survival in both rural and urban areas. In urban areas only, being non-Hispanic black or Hispanic, being US born, more poverty, less community social support, and lower physician density were also associated with lower survival. Conclusions In rural Florida, the demographic characteristics of people diagnosed with AIDS have been changing, which may necessitate modifications in the delivery of AIDS-related services. Rural residents diagnosed with AIDS did not have a significant survival disadvantage relative to urban residents. PMID:23802929

Increasing pro-survival factors within whole brain tissue of Sprague Dawley rats via intracerebral administration of modified valproic acid

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Ryan C. Bates

2015-08-01

Full Text Available Neural tissue exposure to valproic acid (VPA increases several pro-survival phospho-proteins that can be used as biomarkers for indicating a beneficial drug response (pAktSer473, pGSK3βSer9, pErk1/2Thr202/Tyr204. Unfortunately, targeting VPA to neural tissue is a problem due to severe asymmetrical distribution, wherein the drug tends to remain in peripheral blood rather than localizing within the brain. Intracerebral delivery of an amide-linked VPA–PEG conjugate could address these issues by enhancing retention and promoting cerebro-global increases in pro-survival phospho-proteins. It is necessary to assay for the retained bioactivity of a PEGylated valproic acid molecule, along with locating an intracranial cannula placement that optimizes the increase of a known downstream biomarker for chronic VPA exposure. Here we show an acute injection of VPA–PEG conjugate within brain tissue increased virtually all of the assayed phospho-proteins, including well-known pro-survival factors. In contrast, an acute injection of VPA expectedly decreased signaling throughout the hour. Needle penetration into whole brain tissue is the intentional cause of trauma in this procedure. The trauma to brain tissue was observed to overcome known phospho-protein increases for unmodified VPA in the injected solution, while VPA–PEG conjugate appeared to induce significant increases in pro-survival phospho-proteins, despite the procedural trauma.

Cannabinoid receptor-2 immunoreactivity is associated with survival in squamous cell carcinoma of the head and neck.

Science.gov (United States)

Klein Nulent, Thomas J W; Van Diest, Paul J; van der Groep, Petra; Leusink, Frank K J; Kruitwagen, Cas L J J; Koole, Ronald; Van Cann, Ellen M

2013-10-01

The prediction of progression of individual tumours, prognosis, and survival in squamous cell carcinoma (SCC) of the head and neck is difficult. Cannabinoid-1 (CB1) and cannabinoid-2 (CB2) receptor expression is related to survival in several types of cancer, and the aim of this study was to find out whether the expression of CB1 and CB2 receptors is associated with survival in primary SCC of the head and neck. We made immunohistochemical analyses of the cannabinoid receptors on tissue arrays from 240 patients with the disease. Receptor immunoreactivity was classified as none, weak, moderate, or strong staining. Overall survival and disease-specific survival were plotted using Kaplan-Meier survival curves. A multivariate Cox proportional hazard model was created with all the relevant clinical and pathological features. Strong immunoreactivity of the CB2 receptor was significantly associated with reduced disease-specific survival (p=0.007). Cox-proportional hazard ratio (HR) showed that CB2 receptor immunoreactivity contributed to the prediction of survival (HR 3.6, 95% CI 1.5-8.7, p=0.004). Depth of invasion (HR 2.2, 95% CI 1.2-4.2, p=0.01) and vascular invasion (HR 2.5, 95% CI 1.4-4.5, p=0.001) were also associated with survival. Copyright © 2013 The British Association of Oral and Maxillofacial Surgeons. Published by Elsevier Ltd. All rights reserved.

Anterior Overgrowth in Primary Curves, Compensatory Curves and Junctional Segments in Adolescent Idiopathic Scoliosis.

Science.gov (United States)

Schlösser, Tom P C; van Stralen, Marijn; Chu, Winnie C W; Lam, Tsz-Ping; Ng, Bobby K W; Vincken, Koen L; Cheng, Jack C Y; Castelein, René M

2016-01-01

Although much attention has been given to the global three-dimensional aspect of adolescent idiopathic scoliosis (AIS), the accurate three-dimensional morphology of the primary and compensatory curves, as well as the intervening junctional segments, in the scoliotic spine has not been described before. A unique series of 77 AIS patients with high-resolution CT scans of the spine, acquired for surgical planning purposes, were included and compared to 22 healthy controls. Non-idiopathic curves were excluded. Endplate segmentation and local longitudinal axis in endplate plane enabled semi-automatic geometric analysis of the complete three-dimensional morphology of the spine, taking inter-vertebral rotation, intra-vertebral torsion and coronal and sagittal tilt into account. Intraclass correlation coefficients for interobserver reliability were 0.98-1.00. Coronal deviation, axial rotation and the exact length discrepancies in the reconstructed sagittal plane, as defined per vertebra and disc, were analyzed for each primary and compensatory curve as well as for the junctional segments in-between. The anterior-posterior difference of spinal length, based on "true" anterior and posterior points on endplates, was +3.8% for thoracic and +9.4% for (thoraco)lumbar curves, while the junctional segments were almost straight. This differed significantly from control group thoracic kyphosis (-4.1%; P<0.001) and lumbar lordosis (+7.8%; P<0.001). For all primary as well as compensatory curves, we observed linear correlations between the coronal Cobb angle, axial rotation and the anterior-posterior length difference (r≥0.729 for thoracic curves; r≥0.485 for (thoraco)lumbar curves). Excess anterior length of the spine in AIS has been described as a generalized growth disturbance, causing relative anterior spinal overgrowth. This study is the first to demonstrate that this anterior overgrowth is not a generalized phenomenon. It is confined to the primary as well as the

Genotoxic and teratogenic potential of marine sediment extracts investigated with comet assay and zebrafish test

International Nuclear Information System (INIS)

Kammann, Ulrike; Biselli, Scarlett; Huehnerfuss, Heinrich; Reineke, Ninja; Theobald, Norbert; Vobach, Michael; Wosniok, Werner

2004-01-01

Organic extracts of marine sediments from the North Sea and the Baltic Sea were investigated with two toxicity assays. The comet assay based on the fish cell line Epithelioma papulosum cyprini (EPC) was applied to determine the genotoxic potential; zebrafish embryos (Danio rerio) were used to quantify the teratogenic potential of the samples. EC 50 values were calculated from dose-response curves for both test systems. Highest teratogenic and genotoxic effects normalised to total organic carbon (TOC) content were detected in sediment samples of different origins. Polychlorinated biphenyls (PCBs) and polycyclic aromatic hydrocarbons (PAHs) are not likely to be the causes of the observed effects, as demonstrated by a two-step fractionation procedure of selected extracts. The toxic potential was more pronounced in fractions having polarity higher than those possessed by PAHs and PCBs. The suitability of the two in vitro test systems for assessing genotoxic and teratogenic effects of marine sediment extracts could be demonstrated. - Capsule: In vitro toxicity assays are used to assess genotoxic and teratogenic effects of environmental extracts

Development of a statistically-based lower bound fracture toughness curve (Ksub(IR) curve)

International Nuclear Information System (INIS)

Wullaert, R.A.; Server, W.L.; Oldfield, W.; Stahlkopf, K.E.

1977-01-01

A program of initiation fracture toughness measurements on fifty heats of nuclear pressure vessel production materials (including weldments) was used to develop a methodology for establishing a revised reference toughness curve. The new methodology was statistically developed and provides a predefined confidence limit (or tolerance limit) for fracture toughness based upon many heats of a particular type of material. Overall reference curves were developed for seven specific materials using large specimen static and dynamic fracture toughness results. The heat-to-heat variation was removed by normalizing both the fracture toughness and temperature data with the precracked Charpy tanh curve coefficients for each particular heat. The variance and distribution about the curve were determined, and lower bounds of predetermined statistical significance were drawn based upon a Pearson distribution in the lower shelf region (since the data were skewed to high values) and a t-distribution in the transition temperature region (since the data were normally distributed)

[Clinical evaluation of a novel HBsAg quantitative assay].

Science.gov (United States)

Takagi, Kazumi; Tanaka, Yasuhito; Naganuma, Hatsue; Hiramatsu, Kumiko; Iida, Takayasu; Takasaka, Yoshimitsu; Mizokami, Masashi

2007-07-01

The clinical implication of the hepatitis B surface antigen (HBsAg) concentrations in HBV-infected individuals remains unclear. The aim of this study was to evaluate a novel fully automated Chemiluminescence Enzyme Immunoassay (Sysmex HBsAg quantitative assay) by comparative measurements of the reference serum samples versus two independent commercial assays (Lumipulse f or Architect HBsAg QT). Furthermore, clinical usefulness was assessed for monitoring of the serum HBsAg levels during antiviral therapy. A dilution test using 5 reference-serum samples showed linear correlation curve in range from 0.03 to 2,360 IU/ml. The HBsAg was measured in total of 400 serum samples and 99.8% had consistent results between Sysmex and Lumipulse f. Additionally, a positive linear correlation was observed between Sysmex and Architect. To compare the Architect and Sysmex, both methods were applied to quantify the HBsAg in serum samples with different HBV genotypes/subgenotypes, as well as in serum contained HBV vaccine escape mutants (126S, 145R). Correlation between the methods was observed in results for escape mutants and common genotypes (A, B, C) in Japan. Observed during lamivudine therapy, an increase in HBsAg and HBV DNA concentrations preceded the aminotransferase (ALT) elevation associated with drug-resistant HBV variant emergence (breakthrough hepatitis). In conclusion, reliability of the Sysmex HBsAg quantitative assay was confirmed for all HBV genetic variants common in Japan. Monitoring of serum HBsAg concentrations in addition to HBV DNA quantification, is helpful in evaluation of the response to lamivudine treatment and diagnosis of the breakthrough hepatitis.

Survival and hepatitis status among Asian Americans with hepatocellular carcinoma treated without liver transplantation

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Hassan Manal M

2009-02-01

Full Text Available Abstract Background Chronic hepatitis B virus (HBV and hepatitis C virus (HCV are established causes of HCC. HCC patients are often diagnosed late and receive palliative therapies, however, the survival of Asian American patients with HCC treated without transplantation has not been well studied. We reviewed our institution's experience to determine predictors and rates of survival in Asian American HCC patients treated without transplantation. Methods We identified Asian American patients with HCC referred to M. D. Anderson Cancer Center. Patients were tested for HBV and HCV. Survival curves were generated by Kaplan-Meier method. Multivariate Cox proportional hazards regression was used to test the relationship between prognostic factors and survival. Results Of 82 Asian American HCC patients, most had advanced disease (65% and received treatment (68%; however, only 11% had surgical resection. 94% had positive anti-HBc and 61% had positive HBsAg. 20% had positive anti-HCV. There were no significant changes in the rates of HBV and HCV over time. Male gender, high alpha-fetoprotein levels, and stage IV disease were associated with shorter survival Overall median survival was 9.2 months (95% CI 6.5–11.9, and the survival of HCV and HBV patients was not statistically different. Conclusion The survival rate of Asian American patients with advanced HCC, for whom transplantation was not available, was low. Timely hepatitis screening and interventions by primary care physicians may be the most logical solution to reduce the burden of hepatitis-associated HCC among Asian Americans.

Survival advantages conferred to colon cancer cells by E-selectin-induced activation of the PI3K-NFκB survival axis downstream of Death receptor-3

International Nuclear Information System (INIS)

Porquet, Nicolas; Huot, Jacques; Poirier, Andrée; Houle, François; Pin, Anne-Laure; Gout, Stéphanie; Tremblay, Pierre-Luc; Paquet, Éric R; Klinck, Roscoe; Auger, François A

2011-01-01

Extravasation of circulating cancer cells is a key event of metastatic dissemination that is initiated by the adhesion of cancer cells to endothelial cells. It requires interactions between adhesion receptors on endothelial cells and their counter-receptors on cancer cells. Notably, E-selectin, a major endothelial adhesion receptor, interacts with Death receptor-3 present on metastatic colon carcinoma cells. This interaction confers metastatic properties to colon cancer cells by promoting the adhesion of cancer cells to endothelial cells and triggering the activation of the pro-migratory p38 and pro-survival ERK pathways in the cancer cells. In the present study, we investigated further the mechanisms by which the E-selectin-activated pathways downstream of DR3 confer a survival advantage to colon cancer cells. Cell survival has been ascertained by using the WST-1 assay and by evaluating the activation of the PI3 kinase/NFκB survival axis. Apoptosis has been assayed by determining DNA fragmentation by Hoechst staining and by measuring cleavage of caspases-8 and -3. DR3 isoforms have been identified by PCR. For more precise quantification, targeted PCR reactions were carried out, and the amplified products were analyzed by automated chip-based microcapillary electrophoresis on an Agilent 2100 Bioanalyzer instrument. Interaction between DR3-expressing HT29 colon carcinoma cells and E-selectin induces the activation of the PI3K/Akt pathway. Moreover, p65/RelA, the anti-apoptotic subunit of NFκB, is rapidly translocated to the nucleus in response to E-selectin. This translocation is impaired by the PI3K inhibitor LY294002. Furthermore, inhibition of the PI3K/Akt pathway increases the cleavage of caspase 8 in colon cancer cells treated with E-selectin and this effect is still further increased when both ERK and PI3K pathways are concomitantly inhibited. Intriguingly, metastatic colon cancer cell lines such as HT29 and SW620 express higher levels of a splice variant of

Survival advantages conferred to colon cancer cells by E-selectin-induced activation of the PI3K-NFκB survival axis downstream of Death receptor-3

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Paquet Éric R

2011-07-01

Full Text Available Abstract Background Extravasation of circulating cancer cells is a key event of metastatic dissemination that is initiated by the adhesion of cancer cells to endothelial cells. It requires interactions between adhesion receptors on endothelial cells and their counter-receptors on cancer cells. Notably, E-selectin, a major endothelial adhesion receptor, interacts with Death receptor-3 present on metastatic colon carcinoma cells. This interaction confers metastatic properties to colon cancer cells by promoting the adhesion of cancer cells to endothelial cells and triggering the activation of the pro-migratory p38 and pro-survival ERK pathways in the cancer cells. In the present study, we investigated further the mechanisms by which the E-selectin-activated pathways downstream of DR3 confer a survival advantage to colon cancer cells. Methods Cell survival has been ascertained by using the WST-1 assay and by evaluating the activation of the PI3 kinase/NFκB survival axis. Apoptosis has been assayed by determining DNA fragmentation by Hoechst staining and by measuring cleavage of caspases-8 and -3. DR3 isoforms have been identified by PCR. For more precise quantification, targeted PCR reactions were carried out, and the amplified products were analyzed by automated chip-based microcapillary electrophoresis on an Agilent 2100 Bioanalyzer instrument. Results Interaction between DR3-expressing HT29 colon carcinoma cells and E-selectin induces the activation of the PI3K/Akt pathway. Moreover, p65/RelA, the anti-apoptotic subunit of NFκB, is rapidly translocated to the nucleus in response to E-selectin. This translocation is impaired by the PI3K inhibitor LY294002. Furthermore, inhibition of the PI3K/Akt pathway increases the cleavage of caspase 8 in colon cancer cells treated with E-selectin and this effect is still further increased when both ERK and PI3K pathways are concomitantly inhibited. Intriguingly, metastatic colon cancer cell lines such as HT

Development of a toxR-based loop-mediated isothermal amplification assay for detecting Vibrio parahaemolyticus

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Ge Beilei

2010-02-01

Full Text Available Abstract Background Vibrio parahaemolyticus is a leading cause of seafood-related bacterial gastroenteritis and outbreaks worldwide. Sensitive and specific detection methods are needed to better control V. parahaemolyticus infections. This study aimed at developing a highly specific and sensitive loop-mediated isothermal amplification (LAMP assay for detecting V. parahaemolyticus in oysters. A set of five LAMP primers, two outer, two inner, and one loop were designed based on the published V. parahaemolyticus toxR sequence. Specificity of the assay was evaluated using a panel of 36 V. parahaemolyticus and 39 other strains. The assay sensitivity was determined using serial dilutions of V. parahaemolyticus ATCC 27969 culture ranging from 108 CFU/ml to extinction. The assay was also tested in experimentally inoculated oyster samples. Results The toxR-based LAMP assay was able to specifically detect all of the 36 V. parahaemolyticus strains without amplification from 39 other strains. The detection limit was 47-470 cells per reaction in pure culture, up to 100-fold more sensitive than that of toxR-PCR. When applied in spiked oysters, the assay was able to detect 1.1 × 105 V. parahaemolyticus cells per gram of oyster without enrichment, up to 100-fold more sensitive than that of toxR-PCR. Standard curves generated for detecting V. parahaemolyticus in both pure culture and spiked oyster samples showed good linear relationship between cell numbers and the fluorescence or turbidity signals. Conclusions The toxR-based LAMP assay developed in this study was sensitive, specific, and quantitative, holding great potential for future field detection of V. parahaemolyticus in raw oysters.

Calibration and LOD/LOQ estimation of a chemiluminescent hybridization assay for residual DNA in recombinant protein drugs expressed in E. coli using a four-parameter logistic model.

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Lee, K R; Dipaolo, B; Ji, X

2000-06-01

Calibration is the process of fitting a model based on reference data points (x, y), then using the model to estimate an unknown x based on a new measured response, y. In DNA assay, x is the concentration, and y is the measured signal volume. A four-parameter logistic model was used frequently for calibration of immunoassay when the response is optical density for enzyme-linked immunosorbent assay (ELISA) or adjusted radioactivity count for radioimmunoassay (RIA). Here, it is shown that the same model or a linearized version of the curve are equally useful for the calibration of a chemiluminescent hybridization assay for residual DNA in recombinant protein drugs and calculation of performance measures of the assay.

Survival behaviour and virulence of the fish pathogen Vibrio ordalii in seawater microcosms.

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Ruiz, Pamela; Poblete-Morales, Matías; Irgang, Rute; Toranzo, Alicia E; Avendaño-Herrera, Ruben

2016-06-15

Vibrio ordalii, the causative agent of atypical vibriosis, is a Gram-negative, motile, rod-shaped bacterium that severely affects the salmonid aquaculture industry. V. ordalii has been biochemically, antigenically and genetically characterized. However, studies on the survival behaviour of this bacterium in aquatic environments are scarce, and there is no information regarding its disease transmission and infectious abilities outside of the fish host or regarding water as a possible reservoir. The present study investigated the survival behaviour of V. ordalii Vo-LM-06 and Vo-LM-18 in sterile and non-sterile seawater microcosms. After a year in sterile seawater without nutrients, 1% of both V. ordalii strains survived (~10(3) colony-forming units ml(-1)), and long-term maintenance did not affect bacterial biochemical or genetic properties. Additionally, V. ordalii maintained for 60 d in sterile seawater remained infective in rainbow trout Oncorhynchus mykiss. However, after 2 d of natural seawater exposure, this bacterium became non-culturable, indicating that autochthonous microbiota may play an important role in survival. Recuperation assays that added fresh medium to non-sterile microcosms did not favour V. ordalii recovery on solid media. Our results contribute towards a better understanding of V. ordalii survival behaviour in seawater ecosystems.

Correlation between the genotoxicity endpoints measured by two different genotoxicity assays: comet assay and CBMN assay

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Carina Ladeira

2015-06-01

The results concerning of positive findings by micronuclei and non significant ones by comet assay, are corroborated by Deng et al. (2005 study performed in workers occupationally exposed to methotrexate, also a cytostatic drug. According to Cavallo et al. (2009, the comet assay seems to be more suitable for the prompt evaluation of the genotoxic effects, for instance, of polycyclic aromatic hydrocarbons mixtures containing volatile substances, whereas the micronucleus test seems more appropriate to evaluate the effects of exposure to antineoplastic agents. However, there are studies that observed an increase in both the comet assay and the micronucleus test in nurses handling antineoplastic drugs, although statistical significance was only seen in the comet assay, quite the opposite of our results (Maluf & Erdtmann, 2000; Laffon et al. 2005.

A note on families of fragility curves

International Nuclear Information System (INIS)

Kaplan, S.; Bier, V.M.; Bley, D.C.

1989-01-01

In the quantitative assessment of seismic risk, uncertainty in the fragility of a structural component is usually expressed by putting forth a family of fragility curves, with probability serving as the parameter of the family. Commonly, a lognormal shape is used both for the individual curves and for the expression of uncertainty over the family. A so-called composite single curve can also be drawn and used for purposes of approximation. This composite curve is often regarded as equivalent to the mean curve of the family. The equality seems intuitively reasonable, but according to the authors has never been proven. The paper presented proves this equivalence hypothesis mathematically. Moreover, the authors show that this equivalence hypothesis between fragility curves is itself equivalent to an identity property of the standard normal probability curve. Thus, in the course of proving the fragility curve hypothesis, the authors have also proved a rather obscure, but interesting and perhaps previously unrecognized, property of the standard normal curve

Evaluation of possible prognostic factors for the success, survival, and failure of dental implants.

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Geckili, Onur; Bilhan, Hakan; Geckili, Esma; Cilingir, Altug; Mumcu, Emre; Bural, Canan

2014-02-01

To analyze the prognostic factors that are associated with the success, survival, and failure rates of dental implants. Data including implant sizes, insertion time, implant location, and prosthetic treatment of 1656 implants have been collected, and the association of these factors with success, survival, and failure of implants was analyzed. The success rate was lower for short and maxillary implants. The failure rate of maxillary implants exceeded that of mandibular implants, and the failure rate of implants that were placed in the maxillary anterior region was significantly higher than other regions. The failure rates of implants that were placed 5 years ago or more were higher than those that were placed later. Anterior maxilla is more critical for implant loss than other sites. Implants in the anterior mandible show better success compared with other locations, and longer implants show better success rates. The learning curve of the clinician influences survival and success rates of dental implants.

MICA: Multiple interval-based curve alignment

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