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Biomedical subjects

J A Springer

Publications and source records attributed to J A Springer.

10 recordsLinked to original sources
PubMed1991

Dichotic listening failure in dysphoric neuropsychiatric patients who endorse multiple seizure-like symptoms.

In the present investigation, the dichotic word listening performance of a sample of 25 dysphoric neuropsychiatric patients who endorsed multiple partial seizure-like symptoms was compared with that of matched samples of normal controls and patients with mood disorders who did not endorse multiple seizure-like symptoms. Eighty percent of the patients who endorsed multiple episodic phenomena failed the dichotic listening task, compared with 8% of normal controls and 28% of patients with typical mood disorders. After treatment with carbamazepine, a subsample of polysymptomatic patients manifested significantly fewer seizure-like symptoms. This clinical improvement was typically associated with markedly improved dichotic listening performance in most cases. The results are consistent with our previous hypothesis that "subclinical" electrophysiological dysfunction may severely disrupt the normal transmission and processing of auditory information. Because it is sensitive to this type of presumed cerebral dysfunction and relatively specific, impaired dichotic listening performance is likely to be a useful clinical marker for this complex neuropsychiatric syndrome.

Adult↗
PubMed1990

Comparison of the cancer risk of methylene chloride predicted from animal bioassay data with the epidemiologic evidence.

Methylene chloride has been shown to be a lung and liver carcinogen in the mouse; yet, the current epidemiologic data show no adverse health effects associated with chronic exposure to this compound. Hearne et al. have compared the results of a large mortality study on occupational exposure to methylene chloride to the human risk predictions based on the rodent bioassay to point out the inconsistency between the animal toxicologic and human epidemiologic data. The maximum number of lung and liver cancers predicted due to methylene chloride exposure based on the rodent bioassay data was 24 compared to 14 deaths from these cancers actually observed in the Hearne et al. epidemiology study. We assess the minimum risk detectable by the human study in order to calculate the upperbound potency of methylene chloride and compare it to the potency derived from the bioassay data. Results from the epidemiology study imply an upperbound potency of 1.5 x 10(-2) per ppm, compared to 1.4 x 10(-2) per ppm calculated using the most conservative analysis of the animal data. We conclude that the negative epidemiology study of Hearne et al. is not sufficiently powerful to show that the risk is inconsistent with the human risk estimated by modeling the rodent bioassay data. Specifically, the doses to which the workers were exposed, the population studied, and the latency period were not adequate to determine that the risks are outside the bounds of the risk estimates predicted by low-dose modeling of the animal data.

Air Pollutants, Occupational↗
PubMed1987

A guide for mutagenicity testing using the dominant lethal assay.

The dominant lethal assay has been used and continues to be used to provide information about the effects of chemicals on the gonadal cells of male animals. Guidelines for conducting this test are useful but as with any guideline scientists should avoid interpreting them as protocols. Thus this document is a general approach to dominant lethal testing and should be used in conjunction with other available protocols and procedures.

Animals↗
PubMed1986

Asbestos lung cancer risks: comparison of animal and human extrapolations.

Using the most comprehensive inhalation study available, (Wagner, et al., 1974), the dose-response effects of the four major types of asbestos fibers (amosite, anthophyllite, crocidolite, and chrysotile: Canadian, Rhodesian) for lung cancer have been determined. From linear regression analysis of the animal data and five human epidemiology studies giving a wide range of risk estimates, slopes of the curves have been determined and lifetime risk estimates made. Projected risks for rats are presented with and without surface area (s.a.) conversion factors. On the basis of cumulative exposure, the geometric mean of the point estimates for the human studies (0.0146) is quite close to the geometric mean of the animal data (0.0179 without s.a.; 0.0122 with s.a. calculations). These values also match quite well if one of the studies (McDonald, et al.) is eliminated (geometric mean = 0.031) due to qualitatively different exposure considerations (mining and milling vs. industrial environments). Animal risks based on a concentration per day basis (assuming an average 70-year lifespan for humans) are below the lowest human estimate but within 5-6 fold (less) of the projected risk from nonsmoking asbestos workers (2.2 X 10(-3) using the Hammond et al. study.

Animals↗
PubMed1986

Growth of environmental mastitis pathogens in various bedding materials.

The objective of the study was to determine whether, under controlled conditions, bedding materials vary in their ability to support growth of different environmental pathogens independent of the presence of feces, urine, or other contamination. Five sterilized bedding materials (fine hardwood chips, recycled dried manure, chopped newspaper, softwood sawdust, and chopped straw) and three bacterial species (Escherichia coli, Klebsiella pneumoniae, and Streptococcus uberis) were used for a total of 15 bedding/bacteria combinations, replicated in three trials. Samples were incubated at 37 degrees C, and bacterial counts were determined over 5 d. Rapid growth was seen in straw and recycled manure, some growth occurred in hardwood chips, and a rapid decline in bacterial counts was observed in paper and softwood sawdust. In general, K. pneumoniae and E. coli showed more rapid growth or less rapid decline than did S. uberis. These results demonstrate that clean, damp bedding may support bacterial growth and suggest that high bacterial counts under barn conditions are influenced by factors more complex than type of bedding used.

Animals↗
PubMed1976

Protocols for the dominant lethal test, host-mediated assay, and in vivo cytogenetic test used in the food and drug administration's review of substances in the gras (generally recognized as safe) list.

Protocols are described for the dominant lethal and in vivo cytogenetics test in rats and the host-mediated assay, using Salmonella typhimurium and Saccharomyces cerevisiae in mice, as used by the Food and Drug Administration in its mutagenicity review of substances from the generally recognized as safe (GRAS) list. In addition proctolols are described for in vitro mutagenicity tests with S. typhimurium and S. cerevisiae and for statistical treatment for evaluation of data from dominant lethal tests.

Animals↗
PubMed1975

Additional statistical evaluation and pharmacological considerations of hycanthone methanesulfonate-induced dominant lethality.

Investigations of the mutagenicity of hycanthone methanesulfonate (HCT) in mammals have led to varied results. To avoid ambiguous interpretation of significant results previously reported in two dominant-lethal studies of HCT a nested analysis of variance was performed on the number of corpora lutea per pregnant female, the number of implantations per pregnant female, average preimplantation losses, the number of dead implants per pregnant female, and the number of live implants. The analysis showed that variability among males and females was not responsible for the reported significant effects and consequently established the validity of the previous studies. Based on a comparison of the mammalian mutagenicity work performed utilizing hycanthone, pharmacokinetic factors are thought to be responsible for the differences seen; consideration of these factors in the future may lead to fewer false-negative results in mammalian systems.

Analysis of Variance↗
PubMedDate not supplied

Statistical sampling approaches.

This article describes basic sampling principles and the application of statistical sampling techniques to specific problems encountered in the Food and Drug Administration (FDA). Concepts are emphasized, and theory is minimized. The basic principles of sampling from a normal and binomial population, including confidence interval calculation and sample size determination, are briefly reviewed. Stratified, random, systematic, and judgment sampling are explained. Operating characteristic curves for attribute (and perhaps variable) sampling for acceptance of lots are derived and applied to specific FDA problems. The advantages and disadvantages of single and multiple sampling plans and plans which address multiple classes of criteria such as major and minor defects are discussed. Sampling schedules such as MIL-STD-105D and Canada's Government Specifications Board CGSB-105-GP-1 are reviewed to familiarize readers with the principles involved in these plans and to give them an idea of how they could be applied to FDA problems.

Chemistry Techniques, Analytical↗