scholarly journals Evaluation of Sampling Plans to Detect Cry9C Protein in Corn Flour and Meal

2004 ◽  
Vol 87 (4) ◽  
pp. 950-960 ◽  
Author(s):  
Thomas B Whitaker ◽  
Mary W Trucksess ◽  
Francis G Giesbrecht ◽  
Andrew B Slate ◽  
Francis S Thomas
Keyword(s):  
Normal Distribution ◽  
Test Procedure ◽  
Enzyme Linked Immunosorbent Assay ◽  
Sampling Variance ◽  
Regression Equations ◽  
Corn Flour ◽  
Test Procedures ◽  
Sampling Plans ◽  
Sample Test ◽  
Almost All

Abstract StarLink is a genetically modified corn that produces an insecticidal protein, Cry9C. Studies were conducted to determine the variability and Cry9C distribution among sample test results when Cry9C protein was estimated in a bulk lot of corn flour and meal. Emphasis was placed on measuring sampling and analytical variances associated with each step of the test procedure used to measure Cry9C in corn flour and meal. Two commercially available enzyme-linked immunosorbent assay kits were used: one for the determination of Cry9C protein concentration and the other for % StarLink seed. The sampling and analytical variances associated with each step of the Cry9C test procedures were determined for flour and meal. Variances were found to be functions of Cry9C concentration, and regression equations were developed to describe the relationships. Because of the larger particle size, sampling variability associated with cornmeal was about double that for corn flour. For cornmeal, the sampling variance accounted for 92.6% of the total testing variability. The observed sampling and analytical distributions were compared with the Normal distribution. In almost all comparisons, the null hypothesis that the Cry9C protein values were sampled from a Normal distribution could not be rejected at 95% confidence limits. The Normal distribution and the variance estimates were used to evaluate the performance of several Cry9C protein sampling plans for corn flour and meal. Operating characteristic curves were developed and used to demonstrate the effect of increasing sample size on reducing false positives (seller's risk) and false negatives (buyer's risk).

scholarly journals Evaluating the Performance of Sampling Plans to Detect Fumonisin B1 in Maize Lots Marketed in Nigeria

2007 ◽  
Vol 90 (4) ◽  
pp. 1050-1059 ◽  
Author(s):  
Thomas B Whitaker ◽  
M Bruno Doko ◽  
Britt M Maestroni ◽  
Andrew B Slate ◽  
Bosede F Ogunbanwo
Keyword(s):  
Negative Binomial ◽  
Test Procedure ◽  
Fumonisin B1 ◽  
Sampling Plan ◽  
Regression Equations ◽  
Test Results ◽  
Energy Agency ◽  
Sampling Plans ◽  
Sample Test ◽  
Total Variability

Abstract Fumonisins are toxic and carcinogenic compounds produced by fungi that can be readily found in maize. The establishment of maximum limits for fumonisins requires the development of scientifically based sampling plans to detect fumonisin in maize. As part of an International Atomic Energy Agency effort to assist developing countries to control mycotoxin contamination, a study was conducted to design sampling plans to detect fumonisin in maize produced and marketed in Nigeria. Eighty-six maize lots were sampled according to an experimental protocol in which an average of 17 test samples, 100 g each, were taken from each lot and analyzed for fumonisin B1 by using liquid chromatography. The total variability associated with the fumonisin test procedure was measured for each lot. Regression equations were developed to predict the total variance as a function of fumonisin concentration. The observed fumonisin distribution among the replicated-sample test results was compared with several theoretical distributions, and the negative binomial distribution was selected to model the fumonisin distribution among test results. A computer model was developed by using the variance and distribution information to predict the performance of sampling plan designs to detect fumonisin in maize shipments. The performance of several sampling plan designs was evaluated to demonstrate how to manipulate sample size and accept/reject limits to reduce misclassification of maize lots.

Sampling dried figs for aflatoxin – Part 1: variability associated with sampling, sample preparation, and analysis

2017 ◽  
Vol 10 (1) ◽  
pp. 31-40 ◽  
Author(s):  
H. Ozer ◽  
H.I. Oktay Basegmez ◽  
T.B. Whitaker ◽  
A.B. Slate ◽  
F.G. Giesbrecht
Keyword(s):  
Sample Preparation ◽  
Test Procedure ◽  
Portion Size ◽  
Total Variance ◽  
Sampling Variance ◽  
Regression Equations ◽  
Sampling Step ◽  
Test Portion ◽  
Analytical Variance ◽  
Aflatoxin Concentration

The variability associated with the aflatoxin test procedure used to estimate aflatoxins in bulk shipments of dried figs was investigated. Sixteen 10 kg laboratory samples were taken from each of twenty commercial bulk lots of dried figs suspected of aflatoxin contamination. Two 55 g test portions were taken from each comminuted laboratory sample using water-slurry comminution methods. Finally, two aliquots from the test portion/solvent blend were analysed for both aflatoxin B1 and total aflatoxins. The total variance associated with testing dried figs for aflatoxins was measured and partitioned into sampling, sample preparation and analytical variance components (total variance is equal to the sum of the sampling variance, sample preparation variance, and analytical variance). Each variance component increased as aflatoxin concentration increased. Using regression analysis, mathematical expressions were developed to model the relationship between aflatoxin concentration and the total, sampling, sample preparation and analytical variances when testing dried figs for aflatoxins. The regression equations were modified to estimate the variances for any sample size, test portion size, and number of analyses for a specific lot aflatoxin concentration. When using the above aflatoxin test procedure to sample a fig lot at 10 μg/kg total aflatoxins, the sampling, sample preparation, analytical, and total variances were 47.20, 0.29, 0.13, and 47.62, respectively. The sampling, sample preparation, and analytical steps accounted for 99.1, 0.6, and 0.3% of the total variance, respectively. For the aflatoxin test procedure used in this study, the sampling step is the largest source of variability.

Variability and distribution among sample test results when sampling unprocessed oat lots for ochratoxin A

2015 ◽  
Vol 8 (4) ◽  
pp. 511-524 ◽  
Author(s):  
T.B. Whitaker ◽  
A.B. Slate ◽  
T.W. Nowicki ◽  
F.G. Giesbrecht
Keyword(s):  
Ochratoxin A ◽  
Negative Binomial ◽  
Test Procedure ◽  
Regression Equations ◽  
Test Results ◽  
Sampling Step ◽  
Test Portion ◽  
Sample Test ◽  
Total Variability ◽  
Sampling Statistics

In 2008, Health Canada announced it was considering the establishment of maximum levels for ochratoxin A (OTA) in a number of foods, including unprocessed wheat and oats and their products. The Canada Grains Council and Canadian National Millers Association initiated a study to measure the variability and distribution among sample test results so that scientifically based sampling plans could be designed to meet regulatory and industry requirements. Twenty lots of oats naturally contaminated with OTA were identified and sampled according to a nested experimental protocol where 16-two kg laboratory samples were taken from each lot, two 100 g test portions were taken from each comminuted laboratory sample, and two aliquots of the extract from each test portion were analysed for OTA by LC. The variance associated with each step of the OTA test procedure were found to be a function of OTA concentration and regression equations were developed to predict the functional relationship. When using the above OTA test procedure on an oat lot at 5 μg/kg, the sampling, sample preparation, analytical, and total variances were 11.26, 0.10, 0.13 and 11.49, respectively. The 2 kg sampling step accounted for 98.0% (11.26/11.49) of the total variability. The observed OTA distribution among the 16 OTA sample results was found to be positively skewed and the negative binomial distribution was selected to model the OTA distribution among sample test results. The sampling statistics were incorporated into the FAO Mycotoxin Sampling Tool where operating characteristic curves were calculated to predict the chances of rejecting good lots (seller’s risk) and accepting bad lots (buyer’s risk) for various sampling plan designs.

Reliability of Laboratory Tests for the Control of Oral Anticoagulation

1974 ◽  
Vol 32 (02/03) ◽  
pp. 483-491
Author(s):  
E. A Loeliger ◽  
M. J Boekhout-Mussert ◽  
L. P van Halem-Visser ◽  
J. D. E Habbema ◽  
H de Jonge
Keyword(s):  
Human Brain ◽  
Laboratory Tests ◽  
Test Procedure ◽  
Rabbit Brain ◽  
Normal Range ◽  
Test Procedures ◽  
Discrimination Power ◽  
Power Of The Test ◽  
Assay Procedure ◽  
Low Sensitivity

SummaryThe present study concerned the reproducibility of the so-called prothrombin time as assessed with a series of more commonly used modifications of the Quick’s onestage assay procedure, i.e. the British comparative reagent, homemade human brain thromboplastin, Simplastin, Simplastin A, and Thrombotest. All five procedures were tested manually on pooled lyophilized normal and patients’ plasmas. In addition, Simplastin A and Thrombotest were investigated semiautomatically on individual freshly prepared patients’ plasmas. From the results obtained, the following conclusions may be drawn :The reproducibility of results obtained with manual reading on lyophilized plasmas is satisfactory for all five test procedures. For Simplastin, the reproducibility of values in the range of insufficient anticoagulation is relatively low due to the low discrimination power of the test procedure in the near-normal range (so-called low sensitivity of rabbit brain thromboplastins). The reproducibility of Thrombotest excels as a consequence of its particularly easily discerned coagulation endpoint.The reproducibility of Thrombotest, when tested on freshly prepared plasmas using Schnitger’s semiautomatic coagulometer (a fibrinometer-liJce apparatus), is no longer superior to that of Simplastin A.The constant of proportionality between the coagulation times formed with Simplastin A and Thrombotest was estimated at 0.64.Reconstituted Thrombotest is stable for 24 hours when stored at 4° C, whereas reconstituted Simplastin A is not.The Simplastin A method and Thrombotest seem to be equally sensitive to “activation” of blood coagulation upon storage.

First Detection of Tobacco Mosaic Virus in Tobacco Fields in Northern Lebanon

2020 ◽  
Vol 20 ◽  
Author(s):  
Rami Obeid ◽  
Elias Wehbe ◽  
Mohamad Rima ◽  
Mohammad Kabara ◽  
Romeo Al Bersaoui ◽  
...  
Keyword(s):  
Tobacco Mosaic Virus ◽  
Mosaic Virus ◽  
Viral Genome ◽  
Virus Genome ◽  
Enzyme Linked Immunosorbent Assay ◽  
Virus Family ◽  
Crop Fields ◽  
Wide Range ◽  
Almost All ◽  
Das Elisa

Background: Tobacco mosaic virus (TMV) is the most known virus in the plant mosaic virus family and is able to infect a wide range of crops, in particularly tobacco, causing a production loss. Objectives: Herein, and for the first time in Lebanon, we investigated the presence of TMV infection in crops by analyzing 88 samples of tobacco, tomato, cucumber and pepper collected from different regions in North Lebanon. Methods: Double-antibody sandwich enzyme-linked immunosorbent assay (DAS-ELISA), revealed a potential TMV infection of four tobacco samples out of 88 crops samples collected. However, no tomato, cucumber and pepper samples were infected. The TMV+ tobacco samples were then extensively analyzed by RT-PCR to detect viral RNA using different primers covering all the viral genome. Results and Discussion: PCR results confirmed those of DAS-ELISA showing TMV infection of four tobacco samples collected from three crop fields of North Lebanon. In only one of four TMV+ samples, we were able to amplify almost all the regions of viral genome, suggesting possible mutations in the virus genome or an infection with a new, not yet identified, TMV strain. Conclusion: Our study is the first in Lebanon revealing TMV infection in crop fields, and highlighting the danger that may affect the future of agriculture.

scholarly journals Spatial-Temporal and Quantitative Analysis of Growth and EPS I Production by Ralstonia solanacearum in Resistant and Susceptible Tomato Cultivars

1999 ◽  
Vol 89 (12) ◽  
pp. 1233-1239 ◽  
Author(s):  
J. A. McGarvey ◽  
T. P. Denny ◽  
M. A. Schell
Keyword(s):  
Ralstonia Solanacearum ◽  
Antimicrobial Activities ◽  
Enzyme Linked Immunosorbent Assay ◽  
Vascular Bundles ◽  
Susceptible Cultivar ◽  
Bacterial Populations ◽  
Resistant Cultivars ◽  
Cell Densities ◽  
Almost All ◽  
Susceptible Tomato

One susceptible and two resistant cultivars of tomato were tested for differences in infection by Ralstonia solanacearum and for the subsequent multiplication, colonization, and production of the wilt-inducing virulence factor, exopolysaccharide I (EPS I). Bacterial ingress into the taproot was fastest in the susceptible cv. Marion, followed by the resistant cvs. L285 (fivefold slower) and Hawaii 7996 (15-fold slower). Once inside the taproot, R. solanacearum colonized, to some extent, almost all regions of the resistant and susceptible plants. However, colonization occurred sooner in the susceptible than in the resistant cultivars, as measured by viablecell counts of bacteria in the midstems. Rates of multiplication and maximum bacterial cell densities were also greater in the susceptible than in the resistant cultivars. Growth experiments utilizing xylem fluid from infected and uninfected plants indicated that neither antimicrobial activities nor reduced levels of growth-supporting nutrients in the xylem fluids were responsible for the reduced bacterial multiplication in the resistant cultivars. Quantification of EPS I in the infected plants, using an enzyme-linked immunosorbent assay, revealed that the bacterial populations in the susceptible cultivar produced greater amounts of EPS I per plant than those in the resistant cultivars. Immunofluorescence microscopy using antibodies against either EPS I or R. solanacearum cells revealed that bacteria and EPS I were distributed throughout the vascular bundles and intercellular spaces of the pith in the susceptible cultivar, whereas in the resistant cultivars, bacteria and EPS I were restricted to the vascular tissues.

scholarly journals Studies on infant mortality: Part I. Influence of social conditions in county boroughs of england and Wales

1945 ◽  
Vol 44 (2) ◽  
pp. 67-98 ◽  
Author(s):  
Barnet Woolf ◽  
John Waterhouse
Keyword(s):  
Infant Mortality ◽  
Rockefeller Foundation ◽  
Research Work ◽  
Social Conditions ◽  
Infant Mortality Rate ◽  
Past Century ◽  
Sampling Variance ◽  
Regression Equations ◽  
England And Wales ◽  
Latitude Effect

1. The Introduction (pp. 67–73) describes the course of infant mortality in England and Wales over the past century, and critically reviews arguments advanced to prove that variations in the infant mortality rate (i.m.) are caused by genetic differences with respect to viability.2. The i.m. in county boroughs shows a 2-yearly cycle of variability, affecting places with high mortalities.3. We have devised and tested various social indices and have selected five which gave the highest joint covariance with infant mortality in county boroughs during the 11 years 1928–38. These indices are:H, percentage of families living more than 1 person per room.U, percentage of men unemployed.P, percentage of occupied males in the Registrar-General's Social Classes IV and V.F, percentage of women employed on manufacturing processes.L, latitude.4. We have computed multiple regression equations involving i.m. and the five indices for each of the 11 years, and two summarizing equations. The regressions plus sampling variance account for about 80% of the total variance in infant mortality. The regression is linear.5. Latitude does not affect infant mortality in Class I. For this and other reasons we regard the latitude effect as expressing miscellaneous poverty indices omitted from our equations.6. The regression equations enable us to divide the population into various strata with characteristic average infant mortality rates. These include:‘Better off’ (all poverty indices = 0) i.m.=23·1Overcrowded poor i.m. = 108Unemployed overcrowded poor i.m. = 153Babies whose mothers work in industry suffer an additional mortality risk of at least 35 per 1000, and possibly more. The figure 23·1 is the i.m. rate that would prevail if our five poverty symptoms could be eliminated.7. In county boroughs two-thirds of infant deaths would be avoided by the abolition of conditions defined by our indices. Of the preventable deaths, one-third are associated with overcrowding, one-quarter with low-paid occupations, one-fifth with unemployment, and one-eighth with industrial employment of women. In England and Wales, over 250,000 deaths in 11 years, about 63% of the total, can be attributed to adverse social conditions.We have to thank the Rockefeller Foundation for a personal grant to one of us (J. W.) out of an allocation for research work in Prof. Lancelot Hogben's Department, and the Halley Stewart Trust for a grant for mechanical computing equipment. Our thanks are also due to the various members of the Zoology Department in the University of Birmingham who assisted in computing at various times, and especially to Prof. Hogben for his unfailing interest, advice and support.

scholarly journals Experimental Testing of a Size-Exclusion Chromatography Method Used for Evaluation of Molecular Parameters of Equine Anti-Ebola Immunoglobulin

2019 ◽  
Vol 19 (4) ◽  
pp. 261-267
Author(s):  
Е. Yu. Mishalova ◽  
E. V. Gordeev ◽  
V. N. Lebedev ◽  
S. A. Melnikov ◽  
S. A. Nimirskaya ◽  
...  
Keyword(s):  
Specific Activity ◽  
Experimental Testing ◽  
Horse Serum ◽  
Test Procedure ◽  
Size Exclusion ◽  
Array Detector ◽  
Test Procedures ◽  
Molecular Parameters ◽  
Hplc System

Haemorrhagic fever caused by the Ebola virus is a highly hazardous infectious disease with a mortality rate of 50– 90 %. Heterologous immunoglobulins with a high virus-neutralizing titer are an important element of the WHO-endorsed set of measures for emergency prevention and treatment of the disease. Specific activity of these products is largely determined by their fractional composition, and, in particular, by molecular mass distribution (MMD). The size-exclusion-high-performance liquid chromatography (SEC-HPLC) has traditionally been used for determination of the MMD of the target protein in human immunoglobulin-based products. The use of this method for evaluation of molecular parameters of heterologous immunoglobulin requires confirmation of its specificity, accuracy and precision, and establishment of the chromatographic system suitability criteria in the context of a new test object.The aim of the study was to test the applicability of the SEC-HPLC method to the assessment of molecular parameters of anti-Ebola immunoglobulin derived from horse serum.Materials and methods: three batches of purified equine anti-Ebola immunoglobulin were used in the study. Normal equine and human immunoglobulins of the IgG isotype were used as reference standards. The HPLC test procedures described in the European Pharmacopoeia 9.6 and State Pharmacopoeia of the Russian Federation, 14th ed., were used for determination of monomers and other immunoglobulin fractions. An Agilent 1260 Infinity (Agilent, USA) HPLC system with a diode array detector and an Agilent Bio SEC-3 HPLC column were used for quality evaluation of the tested products.Results: the resolution factor between IgG monomer and dimer peaks (1.69 and 2.10), and the chromatographic column efficiency (>2000) make it possible to use the SEC-HPLC system for evaluation of molecular parameters of heterologous immunoglobulin. The study demonstrated reproducibility of the test procedure.Conclusions: the study confirmed the applicability of the SEC-HPLC procedure for evaluation of molecular parameters of anti-Ebola immunoglobulin derived from horse serum. It demonstrated the compliance of the purified immunoglobulin to the national and international quality requirements in terms of «Molecular parameters».

scholarly journals Interrelation among different instability indices of the troposphere over Dhaka associated with thunderstorms/nor'westers over Bangladesh during the pre-monsoon season

MAUSAM ◽  
2021 ◽  
Vol 58 (3) ◽  
pp. 361-368
Author(s):  
SAMARENDRA KARMAKAR ◽  
MD. MAHBUB ALAM
Keyword(s):  
Monsoon Season ◽  
Stability Index ◽  
Dew Point ◽  
Standard Errors ◽  
Regression Equations ◽  
K Index ◽  
Total Index ◽  
Level Of Significance ◽  
Almost All ◽  
Instability Indices

Attempts have been made to correlate different instability indices among themselves statistically. The study reveals that the Showalter Stability Index (SI) has moderate to good correlations with different instability indices except Dew-point Index (DPI), Vertical Total Index (VT), Modified Vertical Total Index (MVT) and Modified K-Index (MK). Most of the correlations co-efficient are found to be significant up to 99% level of significance except Dry Instability Index (DII), which has correlation with SI up to 95% level of significance. Lifted Index (LI) has moderate to good correlation with different instability indices except DII, K-Index (KI) and MVT. Most of the correlations co-efficient are significant up to 99% level of significance except VT, SWEAT Index (SWI) and MKI, which have correlation with LI up to 95% level of significance. Unmodified instability indices have moderate to strong correlation with the corresponding modified instability indices, having 99% level of significance. The correlation co-efficient of VT and MVT, SWI and Modified SWEAT Index (MSWI), and KI and MKI are comparatively large. Standard errors of estimate are small in almost all the cases except a few. The regression equations obtained are likely to be helpful in the computation of different instability indices.

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