Wilbur H. Carter

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To evaluate health effects of chemical mixtures, such as multiple heavy metals in drinking water, we have been developing efficient and accurate hazard identification strategies. Thus, in this study, we determine the cytotoxicity of arsenic, cadmium, chromium, and lead, and characterize interactions among these metals in human epidermal keratinocytes. Three(More)
In work involving modeling of response surfaces to describe the effects of cancer chemotherapy treatments, it is important to define activity and therapeutic synergism in a statistically defensible manner. This requires the construction of confidence intervals around the estimated optimal treatment which has been achieved by use of an indirect method first(More)
Isobolograms have been widely used to characterize the nature of the interaction between combinations of drugs or chemicals. Some authors have applied this technique without accounting for the variability in the data or without adjusting for multiple comparisons to the line of additivity. This paper develops a graphical procedure which takes into account(More)
The precision of the estimated optimum from a response-surface experiment is often indicated via a confidence region about the optimum. Sometimes, because of associated secondary responses, unconstrained optima produce unrealistic operating conditions, even when the true response surface is known. We consider confidence intervals for constrained optima for(More)
The log-rank test or the proportional hazard model is a valuable, widely accepted method for analyzing time-to-response data from comparative clinical trials. When the hazard ratio is constant in time, this procedure is optimal. Indiscriminate or unthinking use of this approach results in problems in the determination of treatment differences. For example,(More)
BACKGROUND Plasma treatment has improved the outcomes in adults with thrombotic thrombocytopenic purpura (TTP)-hemolytic uremic syndrome (HUS). We reviewed our experience in treating unselected patients to determine the clinical outcomes and to evaluate the treatments given in addition to plasma. METHODS A chart review of all cases of TTP and HUS in(More)
We tested serial bone-marrow samples from 47 adults with acute myeloblastic leukemia in remission for reactivity with heteroantiserums to leukemia-associated antigens, to determine whether imminent relapse could be detected in patients with acute leukemia. Of 26 patients who relapsed by standard morphologic criteria, 21 had increased immunoreactivity of(More)
Response surface methods were employed to model survival data obtained in guinea pigs following subcutaneous exposure to soman (GD; 30-84.6 micrograms/kg) with various treatment regimens (i.e., atropine/pralidioxime chloride [ATR/2-PAM] combinations, given im, 1 min post-GD). The analysis of the proportions of surviving animals in the various groups(More)
A pretreatment combination of physostigmine and azaprophen (6-methyl-6-azabicyclo[3.2.1]octan-3-ol-2,2-diphenylpropionate), a novel cholinolytic, was evaluated for its ability to minimize soman-induced incapacitation and lethality in guinea pigs. This was accomplished by using response surface methodology to model and analyze the combination, varying(More)
Environmental exposures generally involve chemical mixtures instead of single chemicals. Statistical models such as the fixed-ratio ray design, wherein the mixing ratio (proportions) of the chemicals is fixed across increasing mixture doses, allows for the detection and characterization of interactions among the chemicals. In this study, we tested for(More)