Search PubMed⌕ Search

Biomedical subjects

R R Jenkins

Publications and source records attributed to R R Jenkins.

31 records · Page 2Linked to original sources
PubMed1986

Effects of beta 1- vs. beta 1- beta 2-blockade on training adaptations in rat skeletal muscle.

The effect of selective vs. nonselective beta-blockade on fast-twitch [extensor digitorum longus (EDL)] and slow-twitch [soleus (SOL)] muscle enzyme activities following endurance training were characterized. Citrate synthase (CS), lactate dehydrogenase (LDH), and beta-hydroxyacyl-CoA dehydrogenase (HAD) activities were compared in SOL and EDL muscles of trained (T), metoprolol-trained (MT), propranolol-trained (PT), and sedentary (C) rats. Following 8 wk of treadmill running (1 h/day, 5 days/wk at approximately 30 m/min), LDH activity was depressed approximately 20% (P less than 0.05) in both SOL and EDL in only the PT rats, indicating inhibition of beta 2-mediated anaerobic glycolysis. EDL CS activity was similarly elevated in all three trained groups compared with sedentary controls. In SOL muscle, however, a drug attenuation effect was observed so that CS activity was increased only in the T (P less than 0.01) and MT (P less than 0.05) groups. HAD enzyme activity was increased somewhat (P less than 0.10) in SOL muscle in only the T group, but more so (P less than 0.05) in EDL in all three trained groups. The above findings suggest a training-induced selectivity effect not only with respect to beta 1-vs. beta 1-beta 2-blockers, but also with respect to muscle fiber type.

3-Hydroxyacyl CoA Dehydrogenases↗
PubMed1984

The relationship of oxygen uptake to superoxide dismutase and catalase activity in human skeletal muscle.

A considerable amount of evidence now makes it clear that aerobic tissues require an elaborate enzyme system to remove the harmful reaction products of oxygen reduction. A portion of this protective system has been studied in human muscle and rat tissues. The VO2 max as well as the superoxide dismutase and catalase activity of vastus lateralis muscle of 12 healthy, male subjects was measured. The subjects with a high aerobic capacity (VO2 max greater than 60 ml . kg-1 . min-1) had significantly greater levels of both superoxide dismutase and catalase. There was also a linear relationship between both superoxide dismutase and catalase and VO2 max. The tissue oxygen consumption, and enzyme activity of the liver, heart, lung, and gastrocnemius from 24 rats was also studied. There VO2 and tissue enzyme activity of both superoxide dismutase and catalase.

Adolescent↗
PubMed1984

Sexual development and behavior in black preadolescents.

As part of a longitudinal study of the sociosexual development of black preadolescents, sexual maturation and sociosexual behaviors were assessed and the relationships between these variables determined in a sample of 101 nine- to eleven-year-old middle- and low-income boys and girls. Sexual maturation was measured by Tanner's staging criteria of specific secondary sex characteristics. Involvement in heterosexual behaviors was elicited via self reports and was classified on a five-point heterosexual physical activity scale (HPA). The data corroborate other studies in demonstrating that girls were more advanced than boys in the process of sexual maturation. Considerable variation in stages of maturation for chronological age existed in both boys and girls, but was more pronounced for girls. In girls, there was no significant association between HPA and degree of biologic maturation. However, genital development in boys was significantly related to their sexual behavior. Income level was not significantly associated with the HPA score. A baseline from which to chart the progress of sociosexual behaviors in these developing preadolescents was established.

Black or African American↗
PubMed1982

Effects of physical training on hypothalamic obesity in rats.

Forty-eight male rats either underwent sterotaxic placement of electrolytic lesions in the ventromedial nucleus of the hypothalamus or had a sham operation and, after a recovery period of at least two weeks, were assigned to either a trained or untrained condition. Training consisted of treadmill running for 120 min per day, 5 days per week, for 12 weeks. At which point all rats were sacrificed to allow the determination of carcass analysis and fat pad lipolysis rates. Both untrained and trained animals with lesions had significantly increased carcass fat. The increased fat content not be attributed to an increased intake since the average daily food consumption of the four groups was not different. Training significantly reduced the fat content in both the lesioned and unlesioned rats. However, the loss in the lesioned rats was about one third less than that of the unlesioned. Training also increased the rate of lipolysis irrespective of whether an animal was lesioned or not. However, the amount of increase was about one third less than in trained normals. Destruction of the ventromedial nucleus of the hypothalamus apparently does not destroy the ability of exercise to alter body composition. The lesions may diminish the capacity of endurance programs to reduce carcass fat. Since the findings relative to lipolysis result from an in vitro investigation, they do not necessarily reflect the events occurring in the in vivo state.

Animals↗
PubMed1982

Adolescent sexuality and the family.

The pediatrician is in an excellent position to provide anticipatory guidance to parents in their attempts to cope with their teenagers' sexuality. The primary approach is early recognition of the child as a "sexual" being. Encouragement of dialogue between parent and child about many issues, including sexuality, appears to be the most natural course. Age-appropriate publications can be used along with parent discussions (not as a substitute for discussion). By the time the child reaches adolescence, a parent should have taken as much opportunity as was given to provide the basis for reasonable decision-making by the adolescent. The parent may offer support and guidance in decision-making, but often finds that dogmatic, obedience-centered dictates fall on deaf ears. Handling one's sexuality is a part of the normative process in attaining adulthood. Adolescents who are developmentally competent should be given full support in taking responsibility for their own sexual behavior. This includes consenting for one's own care when appropriate. A developmental perspective in consideration of the needs of parents and teens provides the framework for the pediatrician to be a resource for both.

Adolescent↗
PubMed1980

Exercise effect during pregnancy on brain nucleic acids of offspring in rats.

Eighteen pregnant female Sprague-Dawley rats were assigned to either a sedentary control, wheelrunning exercise, or a treadmill running condition group. The wheelrunning exercise rats were housed in individual exercise cages, while the treadmill running exercise rats were run on a motor-driven treadmill at 14.23 m/min on an 8% grade for 30 min/day 5 days/wk. The exercise commenced at least 1 week prior to pregnancy and continued to parturition. The wheel running and treadmill running conditions resulted in significantly (p less than 0.05) lower body weights in the dams. No significant differences were observed between the exercise and control groups for the number of pups delivered, the brain weight of the pups, or their body weight. Also, no significant group differences were noted for DNA, RNA, or protein from the brains of the pups. However, the pups of the treadmill running exercise dams performed significantly poorer on a measure of motor performance on a Rotacone.

Animals↗
PubMedDate not supplied

Prevalence of Trichomonas vaginalis in men at high risk for sexually transmitted diseases.

This study determined the prevalence of Trichomonas vaginalis in young men who were at high risk for sexually transmitted diseases; compared different diagnostic tests for trichomonads; and compared sexual behavior of men with positive and negative trichomonas test results. Men (85) aged 16-22 years inclusive, were recruited from a job-training program to participate in this study. Urethral specimens were obtained after prostatic massage for the isolation of Neisseria gonorrhoeae, Chlamydia trachomatis, and trichomonads. The diagnosis of trichomonas infection was made by urethral culture, urine sediment culture, direct examination of urine sediment, direct specimen test (DFA), and Papanicolaou (PAP) smear of urethral swab. Trichomonas vaginalis was seen in 58% of the men, gonorrhoea in 23.5%, chlamydia in 29%, pediculosis in 6%, and condyloma acuminata in 7%, respectively. There was no statistically significant difference in age of the participants, frequency of intercourse, and number of sexual partners in the last 3 months in men with positive and negative trichomonas test results. After controlling for gonorrhoea, pyuria was significantly associated with trichomonas-positive urine (P = .01). No single test was ideal for the diagnosis of trichomonas infection. Using a combination of urethral culture and urine sediment culture as the "gold standard," DFA was 60% sensitive and 73.0% specific. However, urine sediment culture along with DFA identified 94% of all men with positive trichomonas test results.

Adolescent↗