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Biomedical subjects

C W Ahn

Publications and source records attributed to C W Ahn.

5 recordsLinked to original sources
PubMed1992

Pharmacokinetics and toxicity of continuous infusion (6S)-folinic acid and bolus 5-fluorouracil in patients with advanced cancer.

Twenty-seven patients with advanced cancer were entered in a phase I study of bolus i.v. 5-fluorouracil at a dose of 370 mg/m2/day for 5 days combined with a continuous i.v. infusion of (6S)-folinic acid for 5.5 days, starting 24 h in advance of the first 5-fluorouracil dose. The dose of (6S)-folinic acid was escalated in cohorts of patients from 250 mg/m2/day to a maximum of 1000 mg/m2/day. The pharmacokinetics of (6S)-folinic acid were studied in the 3 patients given 250 mg/m2/day and in 6 patients given 1000 mg/m2/day. The mean steady-state plasma concentrations of (6S)-folinic acid and its principal metabolite (6S)-5-methyltetrahydrofolate at the 250 mg/m2/day dose were 2.7 and 5.1 microM, respectively. Both concentrations were comparable to the concentrations produced when (6S)-folinic acid was administered as half of a (6R,S)-folinic acid mixture (E. M. Newman et al., Cancer Res., 49:5755-5760, 1989). At the 1000 mg/m2/day dose of (6S)-folinic acid, the concentration of (6S)-folinic acid was 15.3 microM, more than the 4-fold increase predicted by linear pharmacokinetics, while the concentration of (6S)-5-methyltetrahydrofolate was only 16.5 microM. The change in the ratio of the parent compound to its metabolite was accounted for by a decrease in the nonrenal clearance of (6S)-folinic acid, probably indicating saturation of its metabolism. The toxicities observed in this phase I trial, including stomatitis, diarrhea, neutropenia, and anemia, did not differ in nature or severity from those produced by 5-fluorouracil and (6R,S)-folinic acid when administered on the same schedule. Finally, the degree of toxicity did not appear to depend on the dose of (6S)-folinic acid over the range of doses tested.

Adult↗
PubMed1990

DSM III as a systemic culture pattern: studying intracultural variation among psychiatrists.

DSM III is viewed as embodying a pool of information pertaining to a systemic culture pattern of psychiatry and attempts are made to describe how psychiatrists understand and apply it using ideas from cognitive anthropology. Each of seven psychiatrists evaluated a group of patients in an intake setting. Seven broad categories of Axis I diagnoses were formed and the frequencies with which psychiatrists used these categories were computed. In addition, twelve arithmetical measures pertaining to the five axes of DSM III and a current functioning axis and the decision regarding disposition were also computed. Using these dependent variables, the study analyzes the similarities and differences among psychiatrists in the way they formulate intake evaluations. Psychiatrists' selections of Axis I diagnoses were highly intercorrelated but they differed greatly among themselves in the way they coded many of the axes of DSM III. Group correlations among diagnostic measures indicated a patterning among diagnostic measures and the nature of this patterning is discussed. Each psychiatrists' set of correlations among the twelve diagnostic measures was itself correlated with that of others and this showed a very high level of interpsychiatrist agreement. Deductions drawn from the cultural consensus model suggest that psychiatrists share an underlying 'grammar' that references the pool of information pertaining to DSM III.

Cultural Characteristics↗
PubMed1989

PROPOV-K: a FORTRAN program for computing a kappa coefficient using a proportional overlap procedure.

The computer program PROPOV-K allows the computation of an unweighted kappa coefficient for expressing interrater agreement in the general case in which multiple raters (not necessarily fixed in number) formulate a variable number of multiple diagnoses for each subject. PROPOV-K assesses agreement among lists of multiple diagnoses composed of nonordered categories. PROPOV-K calculates a kappa coefficient on the basis of estimating proportion of agreement between two diagnostic formulations as the ratio of the number of agreements between specific categories over the number of different specific categories mentioned in the two diagnostic lists. When multiple raters formulate a variable number of multiple diagnoses for each subject, the use of a kappa coefficient has been limited to researchers since there are no generally available computer programs. The purpose of this paper is to present a FORTRAN computer program allowing the computation of a kappa coefficient for the case mentioned above and to illustrate its use with examples respectively involving multiple psychiatric and multiple physical diagnoses.

Algorithms↗
PubMedDate not supplied

Explaining diagnostic complexity in an intake setting.

A one patient-one illness paradigm is implicit in the history and theory of psychiatry, and in basic research. Yet, in clinical practice and treatment populations in general, more than one diagnosis per patient is frequently encountered. How clinicians formulate comorbidity by means of DSM-III has rarely been investigated. In this study, the ideas of clinical condition and that of its diagnostic complexity are used to analyze descriptive features of a large number of patients seen in an intake setting. Axis I of DSM-III is used to measure diagnostic complexity. Complexity is analyzed in relation to demographic variables, to ratings entered in the remaining axes of DSM-III formulations, to symptom levels of patients, and to decisions involving disposition. Results indicate that analysis of diagnostic complexity by means of DSM-III yields a definable structure and that it can be related meaningfully to clinical factors. The idea of information uncertainty in diagnosis, i.e., the opacity versus transparency of a clinical condition, is also used to explain results. The ideas introduced and studied are shown to have value for social psychiatric research.

Adaptation, Psychological↗