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Biomedical subjects

C Williams

Publications and source records attributed to C Williams.

At least 577 records · Page 32Linked to original sources
PubMed1983

Exercise metabolism in runners.

The purpose of this study was to re-examine the commonly accepted association between high maximum oxygen uptake (VO2 max) values and the characteristics of metabolic adaptation to endurance training. The metabolic responses of 9 active males and 8 endurance trained females were observed during one hour of treadmill running at two speeds. One speed was common to both groups (3.58 m s-1. Test 1) whereas the second speed represented approximately 62% VO2 max for each individual (Test 2). The VO2 max values of the males were significantly (p less than 0.01) higher than those of the females but observations of the respiratory exchange ratio and of the changes in the concentrations of metabolites were indicative of greater fat metabolism in the well-trained female group in both Tests. Thus the results of this study suggest that the benefits of endurance training are independent of the absolute values of VO2 max.

Adult↗
PubMed1983

Some physiological demands of a half-marathon race on recreational runners.

The purpose of this study was to assess the physiological demands of a half-marathon race on a group of ten recreational runners (8 men and 2 women). The average running speed was 223.1 +/- 22.7 m.min-1 (mean +/- SD) for the group and this represented 79 +/- 5% VO2 max for these runners. There was a good correlation between VO2 max and performance time for the race (4 = -0.81; p less than 0.01) and an even better correlation between running speed equivalent to a blood lactate concentration of 4 mmol.l-1 and performance times (r = -0.877; p less than 0.01). The blood lactate concentration os 4 of the runners at the end of the race was 5.65 +/- 1.42 mmol.l-1 (mean +/- SD) and the estimated energy expenditure for the group was 6.22 M.J. While there was only a poor correlation between total energy expenditure and performance time for the race, the correlation coefficient was improved when the energy expenditure of each individual was expressed in KJ.kg-1 min-1 (r = 0.938; p less than 0.01).

Energy Metabolism↗
PubMed1983

Vasoconstrictor-evoked prostaglandin synthesis in cultured vascular smooth muscle.

We investigated the hypothesis that vasopressin, angiotensin II, and norepinephrine stimulate the synthesis of vasodilatory prostaglandins in cultured vascular smooth muscle cells from rat mesenteric arteries. The major prostaglandin synthesized by subcultured vascular smooth muscle cells was PGI2 (measured as its stable metabolite 6-keto-PGF1 alpha) followed by 1/20th to 1/40th as much PGF2 alpha and PGE2. Vasopressin and angiotensin II dose dependently increased prostaglandin synthesis with a half-maximal stimulatory concentration of the order of 1 X 10(-8) M for both peptides. However, vasopressin could provoke the synthesis of two to three times as much PGI2 as angiotensin II, at maximally effective concentrations. Vasopressin's ability to provoke prostaglandin synthesis depended on its pressor activity as demonstrated by the ability of a potent antipressor analogue of vasopressin, [1-(beta-mercapto-beta,beta-cyclopentamethylenepropionic acid), 2-(O-methyl)tyrosine] arginine vasopressin, to completely inhibit vasopressin-provoked prostaglandin synthesis. Moreover, 1-desamino-8-D-arginine vasopressin, an analogue having full antidiuretic but no pressor activity was much less effective than vasopressin as a prostaglandin-stimulatory agent. Unlike peptide vasoconstrictors, norepinephrine (10(-9) to 10(-5) M) had no ability to stimulate prostaglandin synthesis in vascular smooth muscle cells. We conclude that the potent vasodilator PGI2, released from vascular smooth muscle cells, may buffer the peptide-induced vasoconstriction.

Angiotensin II↗
PubMed1983

Response of the seminiferous epithelium of the mouse exposed to low dose high energy (HZE) and electromagnetic radiation.

This study was undertaken to observe the response of a rapidly dividing cell population (spermatogonial) to Helium and Argon ions as compared to x-rays. Low doses (below 100 rads) were used to more nearly simulate radiation encountered during space missions. The methods used proved compatible for both light and electron microscope studies. The average relative biological effectiveness (RBE) for Helium ions is 1, while Argon is twice as effective in killing spermatogonial cells. Part of this mixed population of cells exhibits a higher sensitivity to radiation below 15 rads. Quantitation of the radiation effects by counting the necrotic cells is not feasible because of their rapid removal, therefore all measurements were done using the surviving fraction (S/So) of spermatogonial cells.

Animals↗
PubMed1982

Measurement of smoking: surveys and some recommendations.

A survey of smoking cessation researchers found considerable disagreement in the measurement procedures used to determine treatment outcome. The survey investigated (1) the duration of the measurement interval used to determine abstinence and smoking rate; (2) procedures for classifying people who smoke after treatment but are abstinent at follow-up; and (3) procedures for classifying people who use marijuana or tobacco products other than cigarettes. The marked disagreement among researchers' survey responses was compounded by the failure of their published articles to explain how smoking had been measured and scored. The Discussion identifies long-term abstinence as the most critical problem; its measurement was least consistent procedurally across studies yet most important for comparing them. Recommendations are made for establishing measurement and reporting conventions.

Follow-Up Studies↗
PubMed1982

Muscle citrate content and the regulation of metabolism in fed and fasted human skeletal muscle.

Blood and muscle metabolite levels were measured in seven healthy young adult male subjects in a fed state and again following a 24-hour fast. Skeletal muscle samples were obtained under local anaesthesia from m.vastus lateralis using a needle biopsy technique. The blood glucose concentration fell during fasting; the blood lactate concentration remained unchanged. Plasma free fatty acid concentrations rose, as did 3-hydroxybutyrate and acetoacetate levels. There was no change in the amount of carbohydrate stored as glycogen in the muscle in response to fasting. The muscle content of phosphagens (adenosine triphosphate and phosphocreatine), glycolytic intermediates (glucose-6-phosphate, fructose-6-phosphate, fructose-1,6-diphosphate, triose phosphates and lactate) and citrate was also not affected by fasting. There was a significant increase in the muscle content of 3-hydroxybutyrate. These results give no indication as to the mechanisms by which a decreased rate of carbohydrate degradation might occur in muscle in the fasted state. It is clear, however, that an intracellular accumulation of citrate and a consequent inhibition of glycolysis at the level of phosphofructokinase does not take place in fasting human skeletal muscle.

Adult↗
PubMed1982

A new case of congenital dyserythropoietic anaemia, type III: studies of the cell cycle distribution and ultrastructure of erythroblasts and of nucleic acid synthesis in marrow cells.

The clinical and laboratory findings in an asymptomatic 19-year-old Welshman with congenital dyserythropoietic anaemia (CDA) type III are described. The blood film showed macrocytosis and red cell fragmentation and there was biochemical evidence of intravascular haemolysis. The bone marrow showed erythroid hyperplasia, megaloblastic erythropoiesis and several giant multinucleate erythroblasts. Some mononucleate erythroblasts were large and had relative DNA contents of 4-8c and the bi- and multinucleate erythroblasts had total DNA contents of 2-16c. Some of the multinucleate erythroblasts displayed a variety of ultrastructural abnormalities, including marked differences in the appearances of the individual nuclei within the same cell. The marrow cells gave a normal deoxyuridine-suppressed value indicating that the megaloblastic changes were not caused by an impairment of the methylation of deoxyuridylate. The rates of incorporation of 14C-glycine and 14C-adenine into both the DNA and RNA of bone marrow cells were within the normal range. Furthermore, the average rate of elongation of newly-synthesised, 3H-thymidine-labelled daughter DNA strands, assessed by hydroxyapatite chromatography of alkali-denatured DNA was found to be normal. The results suggest that there is no impairment of DNA replication in the majority of the erythroblasts and that the abnormality of erythropoiesis resulted from disturbances during mitosis and the G2 phase.

Adenine↗
PubMed1982

Release of lymphotoxin by control and chemical carcinogen-treated lymphocyte cultures derived from black healthy subjects and cancer patients.

In an age-adjusted comparison with white men, black men have a significantly higher increase in esophageal and other types of cancer associated with environmental causes. The basis of this increase in cancer rates in blacks over the last two decades is unknown. Since cancer patients generally show an impairment in cell-mediated immune (CMI) functions, we measured certain CMI reactions in cultured lymphocytes derived from black healthy subjects and cancer patients. We also determined the levels of aryl hydrocarbon hydroxylase (AHH) induced in these lymphocytes. AHH catalyzes the activation of polycyclic aromatic hydrocarbons (PAH) to intermediates which might alter CMI functions.Lymphocytes from 33 black patients with squamous cell carcinoma and 22 healthy volunteers were mitogen-activated with phytohemagglutinin and concurrently treated with the environmental carcinogen, 3-methylcholanthrene (MCA). Measurements were made of the effects of MCA (0.5 to 3.0 μM on blastogenesis, T-cell growth, lymphotoxin (LT) release, and AHH induction in these lymphocyte cultures. MCA treatment depressed blastogenesis but had no depressive effect on T-cell growth in cultures. Blastogenesis and T-cell growth were mitogen dose-dependent, while LT release was independent of mitogen concentration. There was a significantly lower LT release by lymphocytes from lung cancer patients, compared to those from healthy and head/neck cancer subjects. The reduced levels of LT release in lung cancer patients might reflect an impairment in this CMI function. Studies on the role of lymphocyte subpopulations in CMI functions are in progress.

Adult↗
PubMed1981

Behavioral approaches to smoking cessation--I. A decade of research progress 1969-79.

This article describes a topical bibliography presented in the subsequent article in this journal, covering the past decade of research into behavioral approaches to smoking cessation. Using multiple searches including Psychological Abstracts, over 300 references were compiled from over 50 psychology, medicine, and related behavioral science journals. All references were comprehensively coded to each of 28 topical areas of interest to behavioral researchers and clinicians. Topics include specific behavioral smoking cessation techniques (e.g. aversive smoking, relaxation techniques, stimulus control), treatment problems (e.g. maintenance problems and procedures, treatment "side-effects") and important research issues (e.g. predictors of treatment success, physiological correlates of smoking behavior, therapist and treatment factors influencing outcome. An index defining each topic and listing by number all articles related to each topic is included with the bibliography. With this index, users with specialized interests can quickly locate all citations concerning a particular topic or combination of topics, Directions for using the bibliography are given along with guidelines for extending and adopting it for personal use.

Behavior Therapy↗
PubMed1981

Behavioral approaches to smoking cessation--II. Topical bibliography 1969-1979.

This topical bibliography covers that past decade of research into behavioral approaches to smoking cessation. Using multiple sources, including Psychological Abstracts, 335 reference were compiled from over 50 psychology, medicine, and related behavioral science journals. All references were comprehensively coded for each of 28 topical area of interest to behavioral researchers and clinicians. Topics include specific behavioral smoking cessation techniques (e.g. aversive smoking, relaxation techniques, stimulus control), treatment problems (e.g. maintenance problems and procedures, physiological correlates of smoking behavior, therapist and treatment factors influencing outcome). An index defining each topical and listing by number all articles related to each topic is included with the bibliography (Tables 1 and 2). With this index, users with specialized interests can quickly locate all citations concerning a particular topic or combination of topics. The preceding article (Orleans et al., 1981) gives guidelines for expanding this bibliography for personal reference use.

Behavior Therapy↗