PubMed Health⌕ Search

Biomedical subjects

K Y Fung

Publications and source records attributed to K Y Fung.

6 recordsLinked to original sources
PubMed1997

Statistical analysis of the lacI transgenic mouse mutagenicity assay.

The transgenic mouse assay is now widely used to test chemicals for genotoxic potential. In this article, we consider statistical tests for increasing trend in mutant frequency with increasing dose, along with statistical models that may be used to describe the observed dose-response relationships. The application of these methods is illustrated using data on 2-acetylaminofluorene, di(2-ethylhexyl)phthalate, heptachlor, and sodium phenobarbital. No strong evidence of extra-binomial variation was detected at the plate level, but greater evidence was noted when the data were aggregated to the package or animal level in liver, necessitating the use of statistical methods that allow for overdispersion relative to binomial variation. Clear increase on mutant frequency induced by 2-acetylaminofluorene was detected in both liver and bladder, but no apparent trends were noted with di(2-ethylhexyl)phthalate, heptachlor, and sodium phenobarbital. The exponential model provides a good fit to the observed dose-response relationship in liver, whereas a Weibull model provides a better fit for bladder.

2-Acetylaminofluorene↗
PubMed1996

Spinal epidural abscess: a report of nine cases and the use of intra-operative ultrasonography.

BACKGROUND: Spinal epidural abscess is an uncommon and dangerous lesion. Once neurological complications occur the damage is often irreversible. METHODS: The clinical presentation, operative findings, management and follow up of nine cases of spinal epidural abscess were reported. Four patients were diabetic and four others were intravenous drug addicts. The last patient had a history of a protracted stay in an intensive care unit complicated by pneumonia and pleural effusion. Ultrasonography was used intraoperatively to guide and to assess the adequacy of drainage and decompression of the epidural abscess. RESULTS: Multiple level laminectomy was necessary and Staphylococcus aureus was the most common organism cultured. None of the five patients presenting with acute complete paralysis regained neurological function. Two of the four patients with incomplete paralysis were able to walk with an aid. CONCLUSIONS: Spinal epidural abscess usually presents late and the prognosis is generally poor. Ultrasound may be useful in determining the extent of the abscess during operation to drain the collection.

Abscess↗
PubMed1994

Tests for trend in developmental toxicity experiments with correlated binary data.

In this article, the operating characteristics of recently proposed tests for trend in correlated binary data arising in laboratory studies of developmental toxicity are examined using both computer-generated and experimental data. Specifically, we consider adjusted Cochran-Armitge tests based on the Rao-Scott transformation which are of the same general form as that for uncorrelated data. In addition, generalized score tests based on generalized estimating equations allowing for extrabinomial variation in the data are discussed. Specific forms of these statistics demonstrating favorable type I and type II error rates are identified and recommended for use in practice. The application of these tests is illustrated using data from studies of developmental toxicity that have been reported in the literature.

Abnormalities, Drug-Induced↗
PubMed1984

Methodological issues in case-control studies. III--The effect of joint misclassification of risk factors and confounding factors upon estimation and power.

The effect of joint misclassification of polytomous risk factors and polytomous covariates in case-control studies upon estimation and power has been examined using computer simulation and mathematical models. It is concluded that non-differential misclassification of covariates may be as important as non-differential misclassification of exposure variables, and that the resultant bias of the relative risk estimate may be either toward or away from the null. It is pointed out that when a confounding variable is misclassified the calculated p value from the particular study will be incorrect and may either be too large or too small depending on the nature of the confounding.

Clinical Trials as Topic↗
PubMed1976

Cytotoxicity in graft-versus-host reaction. II. Lysis of target cells of parental genotyppe by F1 hybrid macrophages.

Graft-versus-host (GVH) reactions were induced in adult F1 hybrid mice with the i.p. injection of parental strain spleen cells. Peritoneal exudate and spleen cells of the F1 hybrids taken 8 days after the induction of GVH reaction had a nonspecific in vitro cytotoxic effect which was measured by using 51Cr-labeled target cells of parental genotype. The cytotoxic cells in the peritoneal exudates were shown to be macrophages which adhered to plastic surfaces and were sensitive to the toxic action of crystalline silica particles. Moreover, the injection of partially purified syngeneic macrophages into the F1 hybrids undergoing GVH reactions increased the cytotoxic activity of the peritoneal exudate cells obtained from these animals. These results suggest that during GVH reaction host macrophages are activated into a state of nonspecific cytotoxicity.

Animals↗