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Biomedical subjects

G R Ward

Publications and source records attributed to G R Ward.

31 records · Page 2Linked to original sources
PubMed1986

Activation of human muscle pyruvate dehydrogenase with activity and immobilization.

The activity of pyruvate dehydrogenase (PDH) was measured in samples of triceps muscle obtained in 15 males, before and after immobilization for 5 weeks and 5 months of strength training carried out in random order with cross-over of treatment. Although the total PDH activity was unchanged at 300 nmol min-1 g-1, the proportion in the active form increased after strength training (62 +/- 10.1%) and decreased after immobilization (12 +/- 2.3%) compared with control (36 +/- 3.4%). In six subjects measurements were repeated after 10 min maximal exercise (arm ergometer). The proportion of PDH in the active form increased least after immobilization (to 52 +/- 13.6%), compared with control (95 +/- 11.7%) and post-training (98 +/- 6.6%). After exercise muscle glycogen fell to the greatest extent and lactate rose the least in the post-training state, with opposite findings post-immobilization, suggesting that PDH activation contributes to the control of lactate formation in muscle during heavy exercise, and that the effects of training and immobilization are mediated at least in part through changes in the activation of this regulatory enzyme.

Adult↗
PubMed1985

Combined effects of moderate ethanol consumption and a low-protein diet during gestation on brain development in BALB/c mice.

We investigated whether or not moderate ethanol consumption during gestation would interact with the effects of a low-protein diet in affecting brain development in BALB/c mice. The independent variables included fetal body and brain weights and cross-sectional area in midsagittal sections of the corpus callosum (CC) and anterior commissure (CA). Pregnant animals were fed either ethanol 12% v/v or an isocaloric sucrose solution from days 5 to 19 of gestation, when fetal development was assessed. In addition, the animals were fed semisynthetic isocaloric diets containing either 8 or 20% casein. All animals were pair-fed to those in the group receiving ethanol and 20% casein; an additional control group was fed lab chow ad libitum. There was clearly an interactive effect of diet and ethanol consumption on blood alcohol concentrations: those in the low-protein group were significantly higher than in the normal-protein group. Similarly, the effect on body weight in the group receiving low protein plus ethanol was greater than the additive effect of either treatment alone, although this may have been due partly to differences in litter size. Brain weight in this group was also significantly less than in the other three groups, which did not differ from each other. Covariance analysis, adjusting brain weight for body weight, suggested a brain-sparing effect of low protein but not ethanol. Neither treatment affected the incidence of the CC being absent at midline. The low-protein treatment decreased the cross-sectional area of both the CC and CA; the effect on the CC was independent of brain weight. There was no effect of ethanol on either of those measures.

Analysis of Variance↗
PubMed1982

Activation by exercise of human skeletal muscle pyruvate dehydrogenase in vivo.

1. The activity of pyruvate dehydrogenase in its active and inactive forms was measured in biopsy samples obtained from the vastus lateralis muscle of healthy subjects before and after exercise. 2. At rest, 40 +/- 4% (mean +/- SEM) of the enzyme was in the active form. 3. After progressive aerobic exercise to exhaustion (n = 5), 88 +/- 2.3% was in the active form. 4. After intermittent supramaximal short-term exercise (1 min exercise, 3 min rest) to exhaustion (n = 6), 60 +/- 2.2% was in the active form. 5. After isometric maximal exercise of 65 +/- 3.6 s duration (n = 3), only 39 +/- 1% of the enzyme was in the active form. 6. Muscle glycogen depletion was greatest with intermittent exercise and least with isometric maximal exercise; in contrast, the increase in muscle lactate was least with progressive exercise (1.3 to 9.4 mumol/g), intermediate in intermittent maximal exercise (1.2 to 13.1 mumol/g) and greatest after isometric exercise (1.8 to 17.6 mumol/g). There were no significant differences between the three studies in the changes in lactate/pyruvate ratios. 7. In three subjects who exercised with one leg, activation of the enzyme was twice as great in the exercise as in the inactive leg. 8. The ratio of active to total enzyme in biopsies of resting muscle was greater in four well-trained athletes than in four untrained control subjects (70% compared with 41% respectively). 9. The activation of pyruvate dehydrogenase appears to play an important part in regulating the use of glycogen and glucose during exercise in man.

Adult↗
PubMed1980

Distracting information, motor performance and sex differences.

It is often argued that, in general, men are superior to women in perceptual motor skills (for example, car driving). Extensive reviews of the relevant literature do not give convincing evidence of sex differences in manual dexterity or motor skills in general. However, in the studies reported here, variables have been isolated which demonstrate that sex differences do exist in two perceptual motor tasks. These studies showed that females are adversely affected by irrelevant stimuli while performing tasks permitting freedom in movements but perform as well as males when the movement is stereotyped.

Adult↗
PubMed1980

Purine metabolism during strenuous muscular exercise in man.

This study was designed to examine the influence of exercise on purine metabolism in man. In 15 men, the plasma uric acid concentration increased from 6.9 to 8.5 mg/dl following a 5000-m race and from 6.2 to 7.9 mg/dl in 11 men following a 42-km marathon. During a progressive exercise test on a cycle ergometer, the plasma uric acid ocnentration did not change significantly in 11 subjects. However, the plasma oxypurines increased from 19 micrM at rest to 50 microM at exhaustion and the urinary excretion of oxypurines increased from 140 to 400 mumol/g creatinine. Intracellular ATP decreased from 5.17 to 2.91 mumol/g and ADP and AMP increased from 0.85 to 1.29 and from 0.12 to 0.15 mumol/g wet weight, respectively. These observations suggest that there is an accelerated degradation of purine nucleotides to the precursors of uric acid in skeletal muscle during vigorous exercise.

Adenine Nucleotides↗
PubMed1977

Muscle glycogen repletion after high-intensity intermittent exercise.

Six subjects exercised to exhaustion on a cycle ergometer at intensities corresponding to approximately 140% of their maximal aerobic power. Subjects attempted to pedal for 1-min intervals with 3-min rest periods between, and continued until 30 s of exercise could no longer be maintained. Venous blood was sampled for lactate and glucose analysis. Muscle biopsies were extracted from the quadriceps before and immediately after exercise and at 2-, 5-, 12-, and 24-h intervals thereafter for total glycogen analysis. Three subjects consumed a mixed controlled diet (approx. 3,100 kcal) during the 24 h after exercise, and three consumed the same diet plus an additional 2,500/kcal carbohydrate. Following exercise, glycogen concentration had dropped to a mean value of approximately 28% of its preexercise value. After 2 h, it had recovered to 39%, at 5 h to 53%, at 12 h to 67%, and at 24 h to 102% of its preexercise value, with no difference in resynthesis rate between the two groups. It was concluded that, following glycogen depletion through intense intermittent exercise, complete recovery to preexercise values may be accomplished within 24 h; and that within this time period, the rate of resynthesis cannot be accelerated by a higher than normal carbohydrate intake.

Adult↗
PubMed1977

Biochemical adaptation of human skeletal muscle to heavy resistance training and immobilization.

Nine healthy subjects were studied under control conditions and following 5 mo of heavy resistance training and 5 wk of immobilization in elbow casts. Needle biopsies were taken from triceps brachii and analyzed for adenosine triphosphate (ATP), adenosine diphosphate (ADP), creatine (C), creatine phosphate (CP, and glycogen concentrations. Training resulted in an 11% increase in arm circumference and a 28% increase in maximal elbow extension strength. Immobilization resulted in decreases in arm circumference and elbow extension strength of 5% and 35%, respectively. Training also resulted in significant increases in resting concentrations of muscle creatine (by 39%), CP (by 22%), ATP (by 18%), and glycogen (by 66%). Conversely, immobilization significantly reduced CP concentration by 25% and glycogen concentration by 40%. It was concluded that heavy-resistance training results in increases in muscle energy reserves which may be reversed by a period of immobilization-induced disuse.

Adenosine Diphosphate↗
PubMed1975

An empirical comparison of Maslow's and Murray's needs systems.

The Work Motivation Inventory (WMI), a measure of Maslow's hierarchy of needs, and the Edwards Personal Preference Schedule (EPPS), a measure of Murray's manifest needs, were administered to 372 undergraduates. The two instruments were compared using canonical analysis. The analysis revealed three significant relationships between components of the two instruments. The first relationship supported Maslow's need hierarchy in general and its measurement by the WMI. The second suggested a fluctuating relationship between giving and receiving help and the levels of Maslow's hierarchy. The third relationship suggested that need for Achievement is associated with the intermediate levels of Maslow's hierarchy.

Journal Article↗
PubMedDate not supplied

gamma-Linolenic acid fails to prevent the effects of prenatal ethanol exposure on brain and behavioral development in B6D2F2 mice.

The purpose of this study was to obtain a quantitative assessment of the behavioral retardation caused by prenatal ethanol exposure in mice and to test the hypothesis that gamma-linolenic acid (GLA) supplementation would prevent such effects. Pregnant B6D2F1 mice were fed liquid diets containing 25% ethanol-derived calories from days 7-17 of gestation. The experimental groups were given GLA via subcutaneous injection; the control was administered vehicle only. All groups were pair fed to this ethanol control, including a second control group which received sucrose substituted isocalorically for ethanol. Additional control groups included one fed lab chow ad libitum and two further ethanol groups, one treated with coconut oil, the other with arachidonic acid (AA). Behavioral development of the pups was measured on day 32 postconception and open field behavior was measured on day 50. Body and brain weight were also measured. The results indicated that reproductive outcome, as measured by animals which produced live pups, was worse in the GLA- and AA-treated groups. Ethanol produced significant behavioral retardation of the order of 1.7 days. Body and brain weight were lower in ethanol-treated pups. Covariance analysis indicated that the effect on brain weight was independent of the effect on body weight. Open field scores suggested that ethanol-treated males were more active then sucrose controls. The data did not support the hypothesis that GLA would prevent the deleterious effects of prenatal ethanol exposure; in no instance was a GLA-treated group different from the ethanol control.

Animals↗