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Biomedical subjects

J Myers

Publications and source records attributed to J Myers.

At least 235 records · Page 13Linked to original sources
PubMed1981

Potassium maintenance. Potassium supplements or potassium sparing agents.

This paper reviews and presents data from a series of studies evaluating the extent of potassium depletion that occurs in various disease states and a comparison of the efficacy of potassium supplementation or potassium sparing diuretics in its correction. Changes in serum potassium levels are common after diuretics but are relatively minor in most people if small doses of diuretics are used. Total body potassium deficit is uncommon in people treated with a diuretic for hypertension and the fall in serum potassium results from alkalosis and a shift of potassium into the cell. Potassium sparing diuretics correct the potassium abnormality more readily than potassium supplements. Evidence is also presented that suggests that a high salt, low potassium diet may be an important cause of hypokalemia in people given diuretics.

Benzothiadiazines↗
PubMed1981

The social context of occupational disease: asbestos and South Africa.

General issues of industrial health are raised in relation to the production of asbestos and asbestos-related diseases in South Africa., A historical analysis of these diseases and their control in Britain demonstrates some general problems of occupational diseases with long incubation periods and their implications for capital and labor. In order to understand the role of the research establishment, an attempt is made to situate the state in the conflict between capital and labor. The terms and weapons of this ideological arena are investigated. The South African situation is then discussed. Its evident weaknesses--the lack of statutory limits on exposure, capital's responsibility for monitoring exposure and health, the inefficiency of the state inspection, and the meagerness and racial disparities in compensation--are related to the weakness of organized labor. These weaknesses are linked to the movement of certain industrial processes, finally acknowledged as unsafe by most academic research, away from the developed countries. In these countries, the strength of labor and environmental organizations has caused a decline in capitalist productivity.

Asbestos↗
PubMed1981

Sodium intake, blood pressure and red cell sodium efflux.

A series of studies have been undertaken correlating sodium intake, blood pressure and red cell 22Na efflux. The results for male and female patients differ. In male patients with elevated blood pressure, increased sodium intake caused a rise in blood pressure and a fall in red cell 22Na efflux rate. In female patients the results were variable and while certain females followed the above pattern, others had the converse response. Evidence is presented that the change in red cell 22Na efflux is due to a factor in plasma that inhibits the ouabain sensitive component of sodium efflux. This increases after acute and chronic sodium loading and may be similar to natriuretic factor described previously. It is postulated that increased sodium intake causes hypertension by producing a humoral factor that inhibits sodium transport out of cells and that this alters the calcium content of muscle cells and increases their contractility and thus produces hypertension.

Adolescent↗
PubMed1980

On the origins of 718 nm fluorescence from Porphyridium cruentum at 77 K.

Emission spectra and transient behavior of fluorescence in Porphyridium cruentum have been studied in search of the pathway of excitation energy from the phycobilisome to Photosystem I (PS I) of photosynthesis. For activating light at 436 nm, absorbed almost entirely by chlorophyll, fluorescence is dominated by the 718 nm band generally attributed to chlorophyll of PS I. Activating light at 550 nm, absorbed mostly by the phycobilisome, gives rise to the distinctive fluorescence band of PS II chlorophyll at 696 nm but also gives a large component at 718 nm. Analysis depends critically upon the source of emission at 718 nm under 550 nm activation: does it arise from PS I or PS IIC0 Ley and Butler (Ley, A.C. and Butler, W.L. (1976) Proc. Natl. Acad. Sci. U.S.A. 73, 3956-3960) have proposed that the 718 nm arises mostly from PS I, to which it is transferred by spillover from PS II. We suggest a different proposition: that under 550 nm activation most of the 718 emission arises from PS II. Analysis shows that this proposition provides an alternative explanation. Using the small change in fluorescence yield observed under 436 nm activation as a monitor of excitation in PS I, we provide evidence that under 550 activation most of the 718 nm fluorescence arises from PS II.

Darkness↗
PubMed1980

The eight-drug/radiation therapy program (MOPP/ABDV/RT) for advanced Hodgkin's disease: a follow-up report.

Eighty-four evaluable patients with advanced Hodgkin's disease (Stages IIB, IIIA age greater than 35 or mixed cellularity or lymphocyte depletion histology, IIIB, IVA, and IVB) were treated with alternating monthly MOPP and Adriamycin, bleomycin, dacarbazine, and vinblastine (ABDV). Radiation therapy (RT), 2000 rads in two weeks, was given to areas of initial bulky disease in untreated patients. Complete remission (CR) rates were 80% for previously untreated, 65% for prior RT or minimal chemotherapy treated, and 50% for heavily pretreated patients. Among 49 previously untreated patients there were no primary treatment failures. The estimated two-year relapse rate for the CR group was 9%. The therapeutic effectiveness of this program may have been due to either or both of the following elements: (1) two non-cross-resistant drug combinations, (2) low dose adjuvant RT to initial sites of bulky disease. These early results are among the best reported for the treatment of advanced Hodgkin's disease.

Adolescent↗
PubMed1980

Long-term experiences with labetalol.

Labetalol has been used in 83 patients with severe hypertension resistant to a wide number of drugs. Adequate blood pressure control was achieved in 50 patients. Seven patients with a response in blood pressure had administration of the drug ceased because of side effects. Twenty-two of these resistant patients had little fall in blood pressure. Labetalol can be used safely in severe resistant hypertension and is indicated when a thiazide and beta-blocking drug has failed to reduce blood pressure.

Adult↗
PubMed1980

Comparison of piretanide and chlorothiazide in the treatment of cardiac failure.

Piretanide, a diuretic that acts on the loop of Henle, was used to treat patients with cardiac failure. Over a three-day period it caused a significant dose related diuresis and weight loss. It was as effective as chlorothiazide in the control of cardiac failure and was well tolerated by the patients. Potassium loss was less than occurred with chlorothiazide. Its role in the treatment of cardiac failure requires further study and warrants further investigation. The study also showed that many patients with cardiac failure receive diuretic drugs which are not necessary.

Adult↗
PubMed1980

Spontaneous pigment mutants of Anacystis nidulans selected by growth under far-red light.

Under far-red (greater than 650 nm) illumination Anacystis nidulans grows poorly and develops a low chlorophyll content. During continued culture over many generations there are increases in growth rate and in the chlorophyll/phycocyanin ratio, usually occurring in concomitant and stepwise fashion. From such selection cultures six clones have been established which differ from the parent in pigment content and show improved growth rate in far-red light. From the evidence at hand the six clones are presumed to be spontaneous mutants selected under the photosynthetically restrictive condition of far-red illumination.

Chlorophyll↗
PubMed1980

Light Harvesting in Anacystis nidulans Studied in Pigment Mutants.

Spontaneous pigment mutants of Anacystis nidulans were self-selected for improved growth in far red light (> 650 nanometers). Questions were asked about those features of the light-harvesting mechanism which altered to give the mutants improved photosynthetic performance in far red. Answers were sought by comparing pigment and reaction center concentrations for the parent and six mutants grown in gold fluorescent and in far red light. Three significant results emerged. The ratio of reaction centers for photoreactions I and II (RC1/RC2) varied by a value of about 2.1 for all clones grown in gold and a value of about 1.1 for all clones grown in far red. Alteration of the ratio was not evident in any of the mutants.Phycobilisome alterations were evident as decreased phycocyanin content in all mutants. In three mutants, allophycocyanin became the major remaining phycobilisome component. Action spectra for photoreactions I and II allowed estimates of chlorophylls serving each of the two reaction centers. Ratios of chlorophylls to reaction centers within each photosystem were chlorophyll I/RC1 = 118 +/- 11 and chlorophyll II/RC2 = 52 +/- 9 for all seven clones grown in both gold and far red light. Remarkable constancy of these ratios, in spite of wide variation in cell material, supports an hypothesis that in A. nidulans there are two chlorophyll proteins, each bearing a reaction center and chlorophylls in fixed ratio.

Journal Article↗
PubMed1980

Hamster flank organ hydrolase and lipase activity.

The hydrolase and lipase activities of homogenates of the golden Syrian hamster flank organ (sebaceous complex) and skin were studied using synthetic fluorogenic substrates, 4-methylumbelliferone butyrate (4 MUB) or 4-methylumbelliferone palmitate (4 MUP). Homogenates of both flank organ and skin demonstrate a higher level of hydrolase activity (MUB substrate) than lipase activity. Flank organ however is enriched in lipase activity (4 MUP substrate) demonstrating 8 times as much activity as the skin. Systemic androgen treatment of female hamsters significantly stimulates the flank lipase activity while topical estradiol or the antiandrogen flutamide significantly decrease lipase. Testosterone and estradiol have a converse and weaker influence on hydrolase activity suggesting that this activity may be associated with different cell types. These effects do not appear to be direct since these compounds do not inhibit either enzyme in vitro. This data suggests a role for endogenous tissue lipases in the maturation of sebaceous tissue. Tetracycline and retinoic acid inhibit the activity of both enzymes in vitro. Retinoic acid also inhibited both in vivo while tetracycline inhibited only the lipase.

Animals↗
PubMed1979

Is appendicitis familial?

A family history of appendicectomy was sought in two groups of children admitted to Llandough Hospital over sixteen months. The study group consisted of 29 children with histologically confirmed acute appendicitis, while the control group consisted of 29 children admitted for reasons unrelated to abdominal pain. A history of appendicectomy was elicited in first-degree relatives--that is, siblings and parents of 20 of the children in the study group and of four of the controls--a statistically significant difference. The results obtained from this study suggest that a familial predisposition to appendicitis exists.

Acute Disease↗
PubMed1979

Duration of effect of different diuretics.

Twenty-four patients with hypertension were treated with chlorothiazide, chlorthalidone, and frusemide. Each diuretic had a significant and similar antihypertensive effect. After cessation of the administration of diuretics, the antihypertensive effect persisted for a longer time with chlorthalidone than with the other two drugs. The full antihypertensive effect of chlorthalidone and chlorothiazide was still present 24 hours after the administration of the drugs was ceased, and the full effect of chlorthalidone was present 72 hours after the administration of the drug was ceased. Side effects related to a rapid diuresis were more common with frusemide. The study indicated that chlorthalidone could be given at 48-hour or 72-hour intervals, and that other diuretics may be given once daily to exert their full antihypertensive action.

Aged↗