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Biomedical subjects

C D Morris

Publications and source records attributed to C D Morris.

At least 109 records · Page 6Linked to original sources
PubMed1987

The needs and wants of the aged in East London. A preliminary survey.

A pilot survey was conducted among elderly white and black people in East London. The purpose was: to determine whether the facilities available to the white group in this area met their requirements or not; and in view of the scanty facilities for elderly blacks to make a pilot survey of areas of need before undertaking a comprehensive survey of current and future social and medical requirements. The results reveal some fundamental differences; 90% of whites v. 58% of blacks experienced problems with ageing. Loneliness was not a major feature in either group, but about 80% of both white and black single subjects were lonely. Threequarters of the whites but less than one-third of the blacks had a hobby and considered that they were fully occupied. Eighty-one per cent of whites and 40% of blacks saw a doctor regularly, and 88% and 47% respectively took medicine regularly. The white population was not abusing the medical services, but the reasons for the low figures for blacks are not clear. Both groups had a significant demand for spiritual help, emphasising the important role of the clergy in geriatric care. Accommodation was acceptable to 93% of whites but only 25% of blacks. Both groups resisted going to an old-age home, yet 93% of those in a home were happy. This pilot study has confirmed that the services rendered for the white population in East London are adequate, but there is an urgent need for an extensive study of the medical and social expectations and requirements of the black geriatric population.

Black or African American↗
PubMed1987

The calcium paradox of essential hypertension.

Three disparate observations--that calcium mediates vascular smooth muscle contraction, that calcium channel blockers lower blood pressure, and that increased dietary calcium intake can also ameliorate hypertension--constitute somewhat of a paradox. The complex interrelationships between calcium metabolism and essential hypertension are discussed in this review. Recent evidence suggests possible defects in intracellular calcium transport or in calcium binding in essential hypertension. This evidence, and the paradoxical therapeutic efficacy of both calcium channel blockers and supplemental dietary calcium, can be integrated into a single theoretic construct.

Animals↗
PubMed1987

Plasma lipids and hypertension: response to calcium supplementation.

Evidence from animal and human studies indicate that calcium supplementation may ameliorate two risk factors for atherosclerotic cardiovascular disease, hypertension and hyperlipidemia. We sought to characterize dietary fat consumption and plasma lipid profiles in hypertensive and normotensive subjects and plasma lipid responses to supplemental calcium. A randomized, double-blind, placebo-controlled, crossover protocol was used to assess blood pressure and lipid response to 8 wk of 1000 mg of elemental calcium in 43 hypertensive and 27 normotensive subjects. Nutrient intakes and plasma lipids were measured repeatedly. Hypertensive female subjects consumed significantly less (p less than 0.05) phosphorus, potassium, and magnesium and had significantly higher triglycerides (p less than 0.04) and lower HDL-cholesterol (p less than 0.02) than did normotensive subjects. There were no significant changes in dietary plasma lipids with calcium supplementation. Mildly hyperlipidemic normotensive subjects had a significant decrease in total cholesterol (p less than 0.05). No significant changes in plasma lipids occurred with calcium supplementation in hypertensive subjects.

Adult↗
PubMed1987

Ventricular fibrillation survivors in whom tachyarrhythmia cannot be induced: outcome related to selected therapy.

Eight-five patients were studied to determine the prognosis of the ventricular tachyarrhythmias at the time of electrophysiologic study. Twenty-five patients (29%) were not inducible when we used a stimulation protocol consisting of up to four extrastimuli delivered at two right ventricular sites. Patients with no inducible arrhythmias were younger (53 vs 59 yrs; p = .06) and had higher ejection fractions (.49 vs .34; p less than .04) than the inducible ventricular fibrillation survivors. Sex, cardiac diagnosis, time from event to electrophysiologic study, and antiarrhythmic therapy at the time of event did not discriminate between those with and those without inducible ventricular tachyarrhythmias. Survival free of recurrent sudden death or ventricular tachycardia was .86 +/- .05 and .95 +/- .05 for patients with and without inducible tachyarrhythmias, respectively (p = .22). Nine of 25 (36%) patients with no inducible arrhythmias developed inducible ventricular tachyarrhythmias when testing was repeated with an antiarrhythmic drug. Ventricular fibrillation survivors not inducible at the time of programmed ventricular stimulation (using a stimulation protocol consisting of four extrastimuli delivered at two right ventricular sites) seem to have a good prognosis. Many "noninducible" patients develop inducible tachyarrhythmias when placed on antiarrhythmic therapy. Because it is possible that these drugs are proarrhythmic, empiric antiarrhythmic therapy should be avoided in these patients.

Adult↗
PubMed1987

The calcium deficiency hypothesis of hypertension.

The proposed role of maintenance of calcium homeostasis in the prevention and nonpharmacologic treatment of hypertension has prompted controversial interpretations of the data on which the proposal is based. To provide a more current perspective, we summarize the epidemiologic data, results of clinical studies of calcium metabolism in humans with hypertension, effects of controlled interventions of calcium supplementation in humans, and findings from laboratory studies intended to elucidate possible mechanisms. Data from the epidemiologic and clinical trials support a protective role for calcium in regulating arterial pressure. A potentially important relationship between the "calcium hypothesis" and "salt-sensitivity" may provide further insights into the mechanisms involved. Results of experiments in vascular physiology indicate that dietary calcium's effect in lowering blood pressure is mediated in part through direct action on the vasculature.

Animals↗
PubMed1987

Habitat characteristics of Coquillettidia perturbans in central Florida.

Habitat characteristics were examined in two marshes and the littoral zones of two lakes in central Florida to determine their effect on the density and distribution of Coquillettidia perturbans. Larval and water samples were collected and habitat characteristics were recorded at monthly intervals for one year. Several significantly different physicochemical parameters were found between the marshes and lakeshores. Sites with dissolved oxygen less than 1.5 mg/liter (from October through May), pH less than 5.2, total alkalinity less than 6.0 mg CaCO3/liter, and orthophosphate less than 0.25 mg/liter were associated with significantly higher concentrations of Cq. perturbans. Arrow-arum, caric sedge, and maidencane were also associated with higher numbers of Coquillettidia.

Animals↗
PubMed1986

Reproducibility of arrhythmia induction with intracardiac electrophysiologic testing: patients with clinical sustained ventricular tachyarrhythmias.

In order to characterize the day to day reproducibility of arrhythmias provoked during electrophysiologic stimulation, 114 patients with documented sustained clinical ventricular tachyarrhythmias were studied. Two baseline electrophysiologic tests were performed in the drug-free state and within 6 to 24 hours of one another. There was a significant increment (p less than or equal to 0.02) in the induction of sustained ventricular tachyarrhythmias as the number of programmed extrastimuli increased from one (10% induction) to four (64% induction). Provoked arrhythmias were observed to be more frequently nonreproducible (as reflected in a major change in rate or duration, or both, of an induced ventricular arrhythmia between baseline tests) as the number of extrastimuli increased from one (7%) to four (27%). Nonreproducibility with three and four extrastimuli was not significantly greater than when two extrastimuli were utilized. Electrophysiology-directed drug trials should be interpreted in light of this observed variability in induced arrhythmias.

Adolescent↗
PubMed1986

Epidemiological evidence associating dietary calcium and calcium metabolism with blood pressure.

Fourteen reports have identified an association between lower dietary calcium consumption and higher blood pressure in adults. The relationship between dietary calcium and blood pressure status of humans may be modified by a wide variety of demographic, environmental, life-style, and nutritional factors. Reduced dietary calcium intake may be a proximate cause of several of the reported biochemical abnormalities of Ca2+ metabolism including the reductions in serum ionized Ca2+ concentrations and increases in circulating parathyroid hormone levels. The paradoxical increases in intracellular free Ca2+ observed in hypertension on low dietary Ca2+ intake suggest that a primary defect in the cellular handling of Ca2+ may exist, possible mediated through defective Ca2+ adenosine triphosphatase pump activity.

Adolescent↗
PubMed1986

Decreased calcium pump adenosine triphosphatase in red blood cells of hypertensive subjects.

Several operationally defined adenosine triphosphatase (ATPase) activities were determined in vitro in red blood cell lysates of normotensive or hypertensive humans: Mg2+-ATPase, Na+,K+-ATPase, and Ca2+ pump ATPase, the latter in the calmodulin-activated and basal states. Basal Ca2+ pump ATPase was defined as the Ca2+-activated ATPase resistant to 10(-4) M trifluoperazine. Subjects were part of a double-blind study in which treatment was divided into several phases: baseline (4 weeks), placebo or calcium (1 g elemental calcium/day, 8 weeks), placebo washout (4 weeks), placebo or calcium (1 g elemental calcium/day, 8 weeks). Irrespective of the phase of treatment, the basal Ca2+ pump ATPase activity in red blood cell lysates of 36 hypertensive subjects was significantly less than that in lysates from 18 normotensive subjects. Other ATPase activities did not differ significantly, although all ATPases tended to be decreased in hypertension. The data are consistent with previous reports of altered membrane Ca2+ binding and transport in hypertension, but the precise changes are not elucidated.

Adult↗
PubMed1986

Metabolic considerations and cellular mechanism related to calcium's antihypertensive effects.

Whether maintenance of normal calcium homeostasis can afford protection against the development of hypertension in humans has emerged as a controversial area of both clinical and basic cardiovascular disease research. The data that have provoked this debate are derived from epidemiological reports, human studies, animal investigations, and cellular research. Ten published reports have identified an association between greater dietary calcium consumption and lower blood pressure in humans. In both humans and experimental animals with hypertension, several end-organ defects have been identified that are consistent with an inability to maintain external calcium balance. With the provision of supplemental dietary calcium, both humans and experimental models with high blood pressure have reduced their blood pressure. A variety of membrane-associated defects of Ca2+-ATPase-dependent calcium transport have been identified in cells derived from multiple organs of both the hypertensive animal and human. These abnormalities of cellular calcium handling could account for the failure of the hypertensive subject to appropriately defend its calcium balance. More important, they provide a theoretical mechanism by which calcium, interacting with calmodulin, might favorably modify vascular smooth muscle function and, thereby, peripheral vascular resistance.

Animals↗
PubMed1986

Diagnostic value of creatine kinase and creatine kinase MB isoenzyme in chronic hemodialysis patients: a longitudinal study.

Serial measurements of total creatine kinase (CK) and the MB isoenzyme of CK (CK-MB) were performed on 18 stable hemodialysis patients over a 36 month interval in a longitudinal study designed to examine CK and CK-MB variability. Total CK was measured by the DuPont ACA pack procedure. CK-MB was quantitated by the ACA CK-MB ion exchange pack procedure, and by electrophoresis. The mean CK level was 242 +/- 179 IU/l (+/- SD). The mean CK-MB level was approximately 8% of the total CK. Seventy-two percent of the patients had at least one elevated CK level during the course of this study. Depending upon the method of analysis, 88 to 100% of the patients had at least one elevated CK-MB level. Marked and sporadic variations in both total CK and CK-MB levels were apparent, but were not related to the assay. Patients receiving long-term intramuscular androgens had higher CK, but not CK-MB, than did hemodialysis patients not receiving these agents. Discontinuation of the intramuscular androgens for four weeks led to a fall in CK in only one of four patients. Therefore there appears to be a biological effect of exogenous androgens which may play a role in elevating CK in hemodialysis patients.

Adult↗
PubMed1985

Blood pressure response to oral calcium in persons with mild to moderate hypertension. A randomized, double-blind, placebo-controlled, crossover trial.

The blood pressure response of 48 hypertensive persons and 32 normotensive persons to elemental calcium (as the carbonate or citrate salt), 1000 mg/d for 8 weeks, was assessed in a randomized, double-blind, placebo-controlled, crossover trial. Compared with placebo, Ca2+ significantly lowered supine systolic blood pressure by 3.8 mm Hg, standing systolic blood pressure by 5.6 mm Hg (p less than 0.02), and supine diastolic blood pressure by 2.3 mm Hg (p less than 0.05) in hypertensive persons. The response in normotensive persons differed significantly from that in hypertensives (p less than 0.03) as their blood pressure was unchanged. Twenty-one (44%) hypertensive and 6 (19%) normotensive persons achieved a reduction in standing systolic arterial pressure of 10 mm Hg or greater. Reported adverse effects were similar between calcium and placebo phases and did not necessitate withdrawal of any patient from the trial. Treatment with 1000 mg/d of oral Ca2+ for 8 weeks represents a safe, well-tolerated, nonpharmacologic intervention that lowers blood pressure in selected patients with mild to moderate hypertension.

Administration, Oral↗
PubMed1985

Calcium, parathyroid hormone, and hypertension.

Both calcium and parathyroid hormone appear to be involved in the acute and chronic regulation of arterial pressure in experimental animals and humans. While the direct evidence is still preliminary, the net effect of calcium and parathyroid hormone under normal physiologic conditions is to favor a reduction in blood pressure. The implications of this assessment for common medical disorders, such as essential hypertension, and less common but oftentimes more challenging clinical conditions, such as end-stage renal disease, are potentially substantial.

Animals↗