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Biomedical subjects

D L Smith

Publications and source records attributed to D L Smith.

At least 379 records · Page 21Linked to original sources
PubMed1986

Evaluation of physical health effects due to volcanic hazards: crystalline silica in Mount St. Helens volcanic ash.

This investigation has shown that crystalline silica has been identified as being present in the Mount St. Helens volcanic ash at levels of 3 to 7 per cent by weight. This identification has been established using X-ray powder diffraction, infrared spectrophotometry, visible spectrophotometry, electron microscopy, and Laser Raman spectrophotometry. Quantitative analysis by IR, XRD, and visible spectrophotometry requires a preliminary phosphoric acid digestion of the ash sample to remove the plagioclase silicate material which interferes with the determination by these methods. Electron microscopic analysis as well as Laser Raman spectrophotometric analysis of the untreated ash confirms the presence of silica and at levels found by the XRD and IR analysis of the treated samples. An interlaboratory study of volcanic ash samples by 15 laboratories confirms the presence and levels of crystalline silica. Although several problems with applying the digestion procedure were observed in this hastily organized supply, all laboratories employing the digestion procedure reported the presence of crystalline silica. These results unequivocally put to rest the question of the presence of silica in the volcanic ash from eruptions of Mount St. Helens in 1980.

Disasters↗
PubMed1985

Changes in left ventricular hypertrophy and function in hypertensive patients started on continuous ambulatory peritoneal dialysis.

Continuous ambulatory peritoneal dialysis (CAPD) often leads to better control of hypertension. In order to evaluate the effects of such improved blood pressure control on left ventricular (LV) hypertrophy and LV function, a group of 18 patients with a history of hypertension were followed for changes in LV anatomy and function (with M-mode echocardiography) over a 6 to 12 month period after initiation of CAPD. All patients had echocardiographic evidence of increased LV mass related to concentric and eccentric hypertrophy. On CAPD, blood pressure decreased (greater than 5 mm Hg) in 12 patients. LV mass decreased in 15 patients and increased in one. A decrease in both wall thickness and LV dimension contributed to the fall in LV mass on CAPD. Initially, LV dimension exceeded normal in 9 out of 18 patients. On CAPD, LV dimension decreased to near normal in size in six, and no patient developed LV dilation on CAPD. Four patients initially had a decreased fractional shortening and ejection fraction; three of these normalized while on CAPD and no patient deteriorated. These results indicate that CAPD improves LV hypertrophy by normalizing both volume and pressure overload. These effects may prevent deterioration in LV function in patients with still normal LV function, and may improve LV function in patients who already exhibit decreased LV performance.

Adult↗
PubMed1985

Motor function after stroke.

Two hundred and eighty-seven patients who had survived an acute stroke for up to one week after admission to hospital were examined for loss of motor function in the arm and leg. There was a highly significant difference in problem-solving, spatial neglect, communication and postural function between those with significant motor loss and those without. There was no significant difference in memory impairment. Significant loss in motor power had a bad prognosis for functional outcome, length of stay in hospital and survival. If recovery was to occur, it had done so by eight weeks.

Cerebrovascular Disorders↗
PubMed1985

Hemodynamic effects of inhaled ipratropium bromide, alone and combined with an inhaled beta 2-agonist.

Inhaled ipratropium bromide's reported lack of cardiovascular side effects has led to recommendations for its use as a bronchodilator in patients with coexisting cardiovascular disease and in combination regimens with adrenergic agents. To assess the hemodynamic effects of ipratropium, we monitored 10 volunteers by M-mode echocardiography following metered-dose ipratropium administered alone and with fenoterol. On 2 separate days, subjects were monitored for 90 min as they received either 160 micrograms of ipratropium or placebo in divided doses plus 400 micrograms of fenoterol at time 60 min. Following ipratropium alone, heart rate (HR) decreased 3 beats/min, a small but significant difference from placebo (p less than 0.04). Stroke volume (SV) and ejection fraction rose significantly (3 ml and 2%, respectively; p = 0.05) so that cardiac output (CO) was unchanged. By contrast, fenoterol alone (following placebo) produced marked increases in HR (13 beats/min), SV (14 ml), and CO (44%), with a marked fall in total peripheral vascular resistance (29%). Ipratropium administered before and with fenoterol had minimal additive effect. Although SV was slightly higher with the combination of drugs than with fenoterol alone (100.1 ml versus 93 ml; p = 0.05), CO was not significantly greater (6.9 L/min versus 6.4 L/min; p greater than 0.10). We conclude that metered-dose ipratropium alone has small and clinically unimportant hemodynamic effects and produces no clinically significant increases in the cardiovascular side effects of the bronchodilator regimen when given with fenoterol.

Adrenergic beta-Agonists↗
PubMed1984

Evidence that the nucleic acid base queuine is incorporated intact into tRNA by animal cells.

Queuine (the base of queuosine, Q) catalytically reduced with tritium or deuterium yields a derivative in which the proton at C-8 (purine numbering system) has been exchanged and the cyclopentene ring has been reduced to a cyclopentane ring. Mouse fibroblast tRNA has been labeled by culturing the cells in medium supplemented with [3H]- and [2H]dihydroqueuine. Such tRNA yields, upon hydrolysis, the nucleoside dihydroqueuosine and a saccharide derivative of dihydroqueuosine. Each product has been identified unambiguously by mass spectrometry and chromatography. Both the 3H- and 2H-labeled material coeluted, and no unlabeled Q nucleoside was found. Therefore, dihydroqueuine is incorporated intact into tRNA in mammalian cells. Furthermore, fractionation of the labeled tRNA on concanavalin A-agarose, which specifically binds the mannosyl-Q-containing tRNAAsp, has shown that the dihydroqueuosine-containing tRNAAsp is mannosylated. This is the first direct evidence that queuine is incorporated intact into mammalian tRNA in vivo.

Animals↗
PubMed1984

On the identification and biological properties of prostaglandin J2.

Prostaglandin D2 spontaneously decomposes at physiological pH and temperature to 9-deoxy-delta 9-PGD2 (designated PGJ2). We developed a TLC procedure for the isolation of PGJ2 which was identified by both proton-NMR and mass spectrometry. Freshly prepared PGJ2 was active in inhibiting aggregation induced by ADP in citrated human platelet rich plasma. As reported by Fukushima et al. (1). PGJ2 was less active (x 0.1-0.25) than PGD2 as an inhibitor. Concentrations of PGJ2 that markedly inhibited aggregation of human platelets were generally incapable of inhibiting aggregation of rat or guinea pig platelets. Using a heterologous system of human platelets mixed with guinea pig plasma samples (2), it was shown that the ability of PGJ2 to inhibit platelet aggregation was lost immediately following intravenous injection in anesthetized guinea pigs. This apparent rapid uptake and/or degradation of PGJ2 might also explain why PGJ2 had no effect on blood pressure of anesthetized guinea pigs. PGJ2 was potent in inhibiting proliferation of cultured vascular smooth muscle cells, mouse melanoma cells and mouse fibroblasts. Less potent anti-proliferative effects were seen with two other degradation products of PGD2, one of which was the delta 12 metabolite reported (3,4) to be formed from PGJ2 in a reaction catalyzed by serum albumin.

Adenosine Diphosphate↗
PubMed1984

Eicosanoid effects on cell proliferation in vitro: relevance to atherosclerosis.

Several eicosanoids were tested for ability to inhibit proliferation of cells in culture. In rabbit aortic smooth muscle cells and mouse B16BL6 melanoma cells, order of potency was: 12-HETE greater than PGJ2 greater than PGA1 greater than or equal to PGE1 greater than PGE2 greater than or equal to PGD2 greater than or equal to PGA2. PGB1 was active in smooth muscle cells (greater than PGD2) but not in B16 cells. 5-HETE and Leukotriene B4 were weakly active in smooth muscle cells, and PGB2, PGF2 alpha and TXB2 were inactive in both cells types. In Swiss albino mouse 3T3 fibroblasts, PGJ2 and PGE1 showed much lower relative potency than in the other two cell lines, although the profile was otherwise similar. These findings may be relevant to the anti-atherosclerotic (and perhaps anti-tumor activity) of some eicosanoids.

12-Hydroxy-5,8,10,14-eicosatetraenoic Acid↗
PubMed1984

Remedial human factors engineering (Part 2).

The article concludes with comments on panel enhancement techniques, overlays, segmented panel enhancement approaches, factors in selecting between approaches, future modifications, durability, configuration control, cost and practical lessons learned. Part 1 was published in the December 1983 issue on pages 253-264.

Journal Article↗
PubMed1984

Hemodynamic effects of an inhaled beta-2 agonist.

We examined echocardiographically in a single-blind crossover trial the circulatory effects of an inhaled selective beta 2-adrenergic bronchodilator, fenoterol. Eight healthy subjects were studied on the first and fourteenth day after randomly assigned therapy with either no drug or 400 micrograms fenoterol by metered dose inhaler four times a day. Heart rate (HR) and systolic (SBP) and diastolic (DBP) blood pressure responses to fenoterol were small (means +/- SE; HR: +4 +/- 1.3 bpm; SBP: +6 +/- 1.3 mm Hg; DBP: -3 +/- 1.4 mm Hg). In contrast, mean cardiac output increased 26% (1.1 +/- 0.2 l/min), accompanied by an 18% fall in total peripheral vascular resistance (-6 +/- 1.3 U), a 16% increase in stroke volume (+12 +/- 2.5 ml), and an 18% increase in the mean velocity of circumferential shortening (+0.2 +/- 0.04 c/s). Responses varied widely among subjects; maximum observed increase in cardiac output was 117% (+5.48 l/min) in one subject. There was no evidence to suggest development of tolerance to these hemodynamic effects, as the response of measured variables did not differ after 2 wk of regular fenoterol therapy. We conclude that selective beta 2-bronchodilators are not without potential for hemodynamically significant effects when taken by metered inhalers in recommended therapeutic doses and that the magnitude of such effects is underestimated when measured by HR and blood pressure changes.

Adult↗
PubMed1984

Hemodynamic changes during acetate and bicarbonate hemodialysis.

In a crossover, double-blind comparison, circulatory changes induced by hemodialysis with bicarbonate versus acetate dialysate were evaluated at the first exposure as well as after 2 weeks of acclimatization to each dialysate. Hemodialysis with bicarbonate dialysate resulted in only minor changes in blood pressure and left ventricular (LV) function as assessed by M-mode echocardiography. In contrast, the first exposure to acetate resulted in significant decreases in systolic (30 mm Hg) and diastolic (17 mm Hg) blood pressure as well as in LV end-diastolic and end-systolic dimensions (5-6 mm) and a rise in ejection fraction. After acclimatization, tolerance developed for the arterial vasodilatory effects of acetate, but not for the venous vasodilatory effect (persistent decrease in LV end-diastolic dimension). These results indicate that some of the circulatory changes induced by hemodialysis may be related more to the acetate infused than to fluid losses or relative autonomic insufficiency.

Acetates↗
PubMed1984

An analysis of the therapeutic elements in a black church service.

Twenty members of an independent urban black church who frequently attended a midweek service were interviewed to determine the nature of their experiences during the service and to assess its psychological impact. The majority were relatively young, married, and from a Northern urban or Southern rural background. Their responses differed for each of four selected aspects of the service. Testimony was an ineffable and explicitly religious experience. Holy Ghost possession provided an emotionally ecstatic feeling that also produced a sense of relief. Dancing and speaking in tongues were intense individualistic experiences; speaking in tongues was a more explicitly religious phenomenon. The service as a whole imparted feelings of group closeness and strength. The authors note that participants' responses correspond to several curative factors associated with group psychotherapy and suggest that the black church service is a functional community mental health resource for its participants.

Adolescent↗
PubMed1984

Response of rat coronary circulation to carbon monoxide and nitrogen hypoxia.

The effects of nitrogen (N2) or carbon monoxide (CO) hypoxia on coronary flow were assessed in the isolated nonworking rat heart perfused via the aorta with oxygenated (95% O2-5% CO2) Kreb's Henseleit solution. After 30 min, the hearts were challenged with solutions containing either CO (10% CO-85% O2-5% CO2) or N2 (10% N2-85% O2-5% CO2) for 2 min (Challenge I). After recovery in oxygenated solution, the hearts were challenged with the alternate test solution (Challenge II). There were no significant differences in heart rate or pulse pressure between the hearts challenged with CO or N2. Coronary flow was significantly higher in the hearts challenged with CO regardless of the challenge sequence. Coronary flows (ml X min-1 X g dry wt) in the CO- and N2-treated hearts, respectively, were 61.5 +/- 4.5 and 52.9 +/- 2.3 after Challenge I, and 64.3 +/- 2.6 and 56.4 +/- 3.0 after Challenge II. Because PO2 and oxygen content were the same in both test solutions, the results suggest that CO has a direct effect on coronary artery vascular smooth muscle.

Animals↗
PubMed1984

Meeting the psychosocial needs of teen-age mothers and fathers.

The long-term and short-term effects of adolescent pregnancy and parenthood are increasingly significant to all elements of society. The physical, emotional, social, educational, and economic outcomes affect not only the young parents and their children, but also impact on local communities and the nation as a whole. The broad social issues must be addressed through the combined efforts of many groups. The contribution of nursing can be enhanced by the application of a sound theory base and the incorporation of current research findings into individual practice settings.

Adolescent↗