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Biomedical subjects

H B Silva

Publications and source records attributed to H B Silva.

16 recordsLinked to original sources
PubMed1992

Ventricular function by radionuclide ventriculography in malignant hypertension.

Malignant hypertension is a unique and natural model for the study of abnormalities of left ventricular function due to arterial hypertension, because the development and regression of these abnormalities can be observed in a short period. Studies of ventricular function by radionuclide ventriculography, either before or after therapy, have not been previously reported in malignant hypertensive patients. We used this methodology to study left ventricular function in 17 malignant/accelerated hypertensive patients at the time of admission to the hospital and 3, 6, and 9 months after discharge. Seventy percent of patients (12 of 17) had symptoms of congestive heart failure at admission. We compared these data with those obtained in 12 normotensive subjects and 13 mild-to-moderate untreated hypertensive patients. Blood pressure of malignant hypertensive patients was 213 +/- 26/140 +/- 17 mm Hg at admission and 165 +/- 23/101 +/- 15 after 9 months of therapy. Radionuclide ventriculography at admission showed that peak filling rates of malignant hypertensive patients (2.13 +/- 0.21 end-diastolic volume [counts] [EDV]/sec) were significantly lower than those in normotensive subjects (2.40 +/- 0.41) and in mild-to-moderate hypertensive patients (2.46 +/- 0.21). In contrast, peak ejection rates were significantly higher in malignant hypertensive patients (3.44 +/- 0.38 EDV/sec) than in the two control groups (3.01 +/- 0.32 and 3.10 +/- 0.43, respectively). Ejection fractions were similar in the three groups of patients. After 9 months of therapy, peak filling rates of malignant hypertensive patients increased to 2.38 +/- 0.35 EDV/sec, whereas peak ejection rates decreased to 2.89 +/- 0.43 EDV/sec, both not significantly different from data in controls.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1992

Essential hypertension and histocompatibility antigens. An association study.

Data from a previous study concerning the distribution of human leukocyte antigen (HLA) haplotypes in siblings with essential hypertension suggested that at least one of the genes responsible for the genetic susceptibility to this disease is located in or near the HLA complex. The objective of the present study was to investigate if a given HLA-A, B, or DR gene could represent a marker for susceptibility to essential hypertension at the population level. Thus, the frequencies of HLA antigens were determined in Caucasian patients with essential hypertension (HLA-A and B antigens were determined in 89 cases, 85 of which were also typed for HLA-DR antigens). The results showed an increased frequency (p = 0.00064) of HLA-DR4, which was present in 34% of the patients and in 16% of local ethnically matched control subjects. We conclude that HLA-DR4 may represent a marker for susceptibility to essential hypertension in the Brazilian Caucasian population.

Brazil↗
PubMed1992

[Pheochromocytoma. Its diagnostic and therapeutic characteristics].

Pheochromocytoma is a cause of hypertension that frequently can be cured by surgery. The aim of this paper, based on 5 cases of pheochromocytoma, is to relate our experience in diagnosis and treatment in this pathology. In four of 5 patients with pheochromocytoma we observed unusual characteristics of the disease. Association with neurofibromatosis in one case, with rheumatic mitral regurgitation in another; and in a third case the tumor was malignant. One patient had catecholamine-mediated electrocardiographic changes which disappeared with treatment. Since symptoms of adrenergic hyperactivity were present in all cases, the rise in the levels of vanilmandelic acid and urinary metanephrines were useful in confirming the diagnosis. Computed tomography and I-131 meta-benzylguanidine for radioisotopic imaging, displayed not only all tumoral masses but also bone metastases in the malignant case. During the follow-up period, from the sixth month to the fourth year after surgery, four patients were asymptomatic, and have normal urinary catecholamine metabolite levels. The patient with a malignant form of pheochromocytoma continued to show elevated catecholamines release and remained hypertensive in spite of adrenal mass resection.

Adrenal Gland Neoplasms↗
PubMed1990

[Efficacy and tolerance of a new calcium-channel blocking agent (nitrendipine) in the treatment of arterial hypertension].

PURPOSE: Assess the efficacy and tolerability of nitrendipine, 20 mg/day, in mild to moderate essential hypertension (diastolic blood pressure 95 to 114 mmHg). MATERIAL AND METHODS: Twenty patients in an open comparative trial (drug x placebo) during six weeks. Blood pressure and heart rate were measured in orthostatic and supine position and after hand-grip maneuver every two weeks. RESULTS: Systolic and diastolic blood pressure fell significatively in the treated group by the end of the study-supine (161 mmHg +/- 11 to 138 mmHg +/- 13 and 105 +/- 5 to 81 mmHg +/- 7 p less than 0.05) and orthostatic position (153 mmHg +/- 13 to 132 mmHg +/- 13 and 104 mmHg +/- 15 to 81 mmHg +/- 7, p less than 0.05) and after hand grip maneuver (170 mmHg +/- 21 to 148 mmHg +/- 22 and 108 mmHg +/- 5 to 85 mmHg +/- 7 p less than 0.05). Significant modifications were not observed in systolic and diastolic blood pressure in placebo group under the following conditions: supine (168 mmHg +/- 8 to 168 mmHg +/- 17 and 107 mmHg +/- 5 to 107 mmHg +/- 3) and orthostatic positions (167 mmHg +/- 9 to 163 mmHg +/- 14 and 107 mmHg +/- 5 to 107 mmHg +/- 4) and after hand grip maneuver (178 mmHg +/- 17 to 173 mmHg +/- 16 and 107 mmHg +/- 4 to 108 mmHg +/- 6). Significant changes in heart rate did not occur in both groups after treatment. Heart rate elevation observed after hand grip maneuver did not change. Adverse effects like headache, palpitation and dizziness occurred in both groups. Electrocardiogram, x-ray and blood chemistries were not modified during the trial.

Adult↗
PubMed1989

Essential hypertension and histocompatibility antigens. A linkage study.

It is well established that genetic and environmental factors are involved in the etiology of essential hypertension. The presence of genes predisposing to essential hypertension in the human leukocyte antigen (HLA) complex is controversial because studies of an association between HLA antigens and essential hypertension have failed to yield consistent results. Our aim in the present study was to further investigate this issue through the method of linkage analysis. Analysis of 96 hypertensive siblings distributed in 31 families indicated a significant distortion (p = 0.0009) of the normal segregation pattern of inheritance of HLA haplotypes. Thus, our data indicate that at least one of the genes responsible for genetic predisposition to essential hypertension is located very near or within the HLA complex.

Adolescent↗
PubMed1979

Long-lasting inhibition of angiotensin response in rats by depot administration of octanoyl-[Leu8]-angiotensin II.

Depot administration of a lipophilic angiotensin II (AII) antagonist was tested for obtaining prolonged inhibition of the pressor response to AII in rats. Intramuscular injections of 1.5 or 5.0 mg of octanoyl-[Leu8]AII (oct-LAII), in oil solution produced the same degree of AII inhibition either 6 h or 24 h after the injection. The inhibition was comparable to that expected from the continuous intravenous infusion of oct-LAII at the rate of 1.2 microgram kg-1 min-1. The prolonged effect of intramuscular injections of oct-LAII in oil solution may be useful for chronic studies of physiopathological states involving the renin-angiotensin-aldosterone system.

Angiotensin II↗
PubMed1978

The effect of serum ionized calcium elevation on somatostatin inhibition of glucose-induced insulin release in humans.

The effect of somatostatin on the insulin response to an acute intravenous glucose load was studied in five normal subjects before and after induction hypercalcaemia. In the normocalcaemic state, the insulin response to glucose was depressed by somatostatin. In the hypercalcaemic state, insulin responses to glucose in the presence of somatostatin, were partially restored and appeared to be related to the level of increment of serum ionized calcium. It is concluded that, in the human being, hypercalcaemia and somatostatin have opposite actions on glucose-stimulated insulin secretion.

Adult↗
PubMed1977

Interaction of calcium ions with serum albumin in chronic renal failure.

In order to study the effect of the uremic environment on serum calcium-albumin interaction, ten adult subjects with chronic renal failure (creatinine clearances below 20 ml/min) and five adult normal subjects, had their serum ionic calcium (Orion SS-20) determined at three different serum pH values. At similar serum protein levels, the correlations between serum ionic calcium pH were: (a) normals: number of pairs = 15, r = -0.90, p less than 0.01, Ca2+ = 4.54-0.484 pH. (b) uremics: number of pairs=15, r=-0.97, p less than 0.01, Ca2+=4.02-0.429 pH. These regressions were similar as far as the slopes (Fslope=0.62, p greater than 0.05) but had different intercepts (Fintercepts=64.34, p less than 0.01). These results confirm that uremics, when compared to normal subjects, present an ionic hypocalcemia at any level of serum pH. They also show that serum calcium-albumin interaction is normal in uremia. In view of the above results, it can be suggested that, among several possible causes, alterations in the binding-affinity of calcium ions to serum albumin can be excluded as an additional factor of secondary hyperparathyroidism in uremia.

Adult↗
PubMed1975

Renal tubular sodium reabsorption during the recovery from the oliguric phase of acute nephritis.

The urinary excretion of sodium, calcium, phosphorus and the reabsorption of solute free-water, were studied in seven water-restricted patients with post-streptococcal acute glomerulonephritis. During the recovery from the initial salt-retaining phase, there was a progressive increase in the urinary excretion of sodium, phosphorus and calcium either in absolute values or when expressed as their tubular rejection fractions. A progressive increase in free-water reabsorption as percentage of creatinine clearance was also demonstrated. The data suggest that in this phase of the disease there occurs a non specific supression of proximal tubular activity.

Absorption↗