Biomedical subjects

A M Linares

Publications and source records attributed to A M Linares.

4 recordsLinked to original sources

PubMed2001

Endogenous concentrations of DHEA and DHEA-S decrease with remission of depression in older adults.

BACKGROUND: Clinical studies of endogenous concentrations of dehydroepiandrosterone (DHEA) and its sulfated conjugate DHEA-S in depression are limited. This study was designed to evaluate the influence of successful pharmacological treatment of late-life depression on concentrations of DHEA, DHEA-S and cortisol. METHODS: We determined endogenous concentrations of DHEA, DHEA-S and cortisol in elderly control subjects (n = 16) and in elderly depressed patients who remitted (n = 44) or failed to remit (n = 16) with pharmacological treatment. Depressed patients were treated for 12 weeks with either nortriptyline or paroxetine. RESULTS: In remitters, DHEA and DHEA-S concentrations were lower at week 12 than at week 0 (p =.002 and p =.0001, respectively). In the nonremitters and control subjects, neither DHEA nor DHEA-S concentrations changed. Decreases in hormone concentrations were associated with improvement in mood and functioning in depressed patients. Although cortisol concentrations decreased in remitters and nonremitters, the change was not significant. CONCLUSIONS: Our data suggest that the decrease in DHEA and DHEA-S in remitters is related to remission of depression rather than to a direct drug effect on steroids, as nonremitters had no change in hormone concentrations.

Aged↗

PubMed2000

Sex differences in the pharmacokinetics of dehydroepiandrosterone (DHEA) after single- and multiple-dose administration in healthy older adults.

The pharmacokinetics of exogenously administered DHEA have not been well characterized despite its increasing use in therapeutic and research investigations. The purpose of this study was to evaluate the pharmacokinetics of DHEA and its sulfated metabolite (DHEA-S) after single- and multiple-dose oral administration of DHEA 200 mg. Healthy older adult volunteers (7 women, 6 men) ages 65 to 79 years were studied on five visits separated by 1 week. Subjects received daily administration of placebo (days 1 to 7), DHEA 200 mg (days 8 to 22), and placebo (days 23 to 29). Blood samples were collected over 24 hours on days 1, 8, 15, 22, and 29 for DHEA and DHEA-S determinations by RIA. Pharmacokinetic parameter estimates were calculated by noncompartmental methods. Administration of DHEA 200 mg resulted in higher DHEA Cmax, AUC, and overall concentrations in women than in men (p < 0.03); DHEA-S parameter estimates were similar between men and women. Following a single dose of DHEA 200 mg, DHEA concentrations increased 5- to 6-fold in both men and women, and DHEA-S concentrations increased 5-fold in men and 21-fold in women relative to endogenous concentrations. The results of this study indicate that the pharmacokinetics of DHEA differ between older men and women.

Aged↗

PubMed1990

Ethical principles of biomedical research on human subjects: their application and limitations in Latin America and the Caribbean.

Biomedical research on human subjects involves certain ethical principles, several of which are described in this article. It is also true, however, that application of these principles in real life poses problems, especially in the case of international research conducted under culturally diverse conditions. This presentation examines certain cultural and institutional circumstances prevailing in much of Latin America and the Caribbean that show a predilection to pose problems of this kind. This is not done to encourage research without ethical principles, but rather to familiarize investigators with cultural differences, so that these differences can be considered when studies on human subjects are being conducted, thereby improving the prospects for beneficial research that respects ethical principles within different cultural contexts.

Beneficence↗

PubMedDate not supplied

[Ethical principles of biomedical research in humans: application and limitations in Latin America and the Caribbean].

The characteristics and limitations that investigators in developed countries should take into account in conducting biomedical research on human subjects in regions such as Latin America and the Caribbean are reviewed. The authors first cite international ethical principles that have been established in the developed countries to serve as a guide in dealing with the ethical problems that arise in this type of research. These principles should always be borne in mind by every investigator, regardless of the country where the research is being done. The paper goes on to briefly review some of the circumstances in certain Latin American and Caribbean countries that could pose practical limitations for direct application of the ethical principles described.

Ethics, Medical↗