Biomedical subjects

Richard Buchta

Publications and source records attributed to Richard Buchta.

3 recordsLinked to original sources

PubMed2004

Decrease in measles virus-specific CD4 T cell memory in vaccinated subjects.

Since the licensure and generalization of an effective measles virus (MV) vaccine 41 years ago, antibody levels have been used as correlates of immunity. The long-lived MV-specific antibody response has been studied intensely, but the dynamics of MV-specific T cell immunity over time have not been well characterized. We thus characterized the profiles of MV vaccine-induced antigen-specific T cells over time since vaccination. In a cross-sectional study of healthy subjects with a history of MV vaccination, we found that MV-specific CD4 and CD8 T cells could be detected up to 34 years after vaccination. The levels of MV-specific CD8 T cells and MV-specific IgG remained stable, whereas the level of MV-specific CD4 T cells decreased significantly in subjects who had been vaccinated >21 years earlier. These results show that MV-specific T cell immunity after vaccination is long lasting and reveal different dynamics between CD4 and CD8 cells after vaccination.

Adolescent↗

PubMed2004

Simultaneous determination of tretinoin and clindamycin phosphate and their degradation products in topical formulations by reverse phase HPLC.

A new HPLC method based on reverse phase separation and photodiode-array detection has been developed for the simultaneous determination of tretinoin and clindamycin phosphate, and their degradation products in topical formulations. The method has been shown to be stability indicating, accurate, and precise for two different formulation vehicles. Separation was achieved on a reverse phase C18 column (Lichrospher, RP18, 5 microm, 25 cm x 4.6 mm ID, Phenomenex, USA) using a simple gradient with aqueous-acetonitrile and aqueous-methanol mobile phases. The method recovery averaged 100.3% for tretinoin and 99.6% for clindamycin phosphate at a concentration range between 80% and 120% of the label claim. The method can be applied to assess the stability of tretinoin and clindamycin phosphate in pharmaceutical formulations containing tretinoin and clindamycin phosphate individually or in combination as active drugs.

Administration, Topical↗

PubMed2002

Behavioral weight control for overweight adolescents initiated in primary care.

OBJECTIVE: This study evaluates the post-treatment and short-term follow-up efficacy of, as well as participant satisfaction for, a 4-month behavioral weight control program for overweight adolescents initiated in a primary care setting and extended through telephone and mail contact. RESEARCH METHODS AND PROCEDURES: 44 overweight adolescents were randomly assigned to either a multiple component behavioral weight control intervention (Healthy Habits [HH]; n = 23) or a single session of physician weight counseling (typical care [TC]; n = 21). Weight, height, dietary intake, physical activity, sedentary behavior, and problematic weight-related and eating behaviors and beliefs were assessed before treatment, after the 4-month treatment, and at 3-month follow-up. Participant satisfaction and behavioral skills use were measured. RESULTS: HH adolescents evidenced better change in body mass index z scores to post-treatment than TC adolescents. Body mass index z scores changed similarly in the conditions from post-treatment through follow-up. Behavioral skills use was higher among HH than TC adolescents, and higher behavioral skills use was related to better weight outcome. Energy intake, percentage of calories from fat, physical activity, sedentary behavior, and problematic weight-related or eating behaviors/beliefs did not differ by condition or significantly change over time independent of condition. The behavioral intervention evidenced good feasibility and participant satisfaction. DISCUSSION: A telephone- and mail-based behavioral intervention initiated in primary care resulted in better weight control efficacy relative to care typically provided to overweight adolescents. Innovative and efficacious weight control intervention delivery approaches could decrease provider and participant burden and improve dissemination to the increasing population of overweight youth.

Adolescent↗