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Biomedical subjects

H Silva

Publications and source records attributed to H Silva.

At least 55 records · Page 3Linked to original sources
PubMed1987

Effect of prazosin and propranolol on lipoproteins of hypertensive patients.

A comparative study between prazosin and propranolol with twenty male patients with mild to moderate essential hypertension was used to study the effects of these antihypertensive agents on plasma lipoproteins, and more specifically high density lipoproteins-2 and Apo A-I. After 4 weeks on placebo, the patients were randomly assigned to prazosin therapy (Group A) and other ten patients to propranolol therapy (Group B) for 8 weeks. Doses required for normalization of blood pressure ranged between 1 to 8 mg/day for prazosin and 20 to 240 mg/day for propranolol. The mean blood pressure was lowered to normal by both drugs. The results indicate that prazosin has no adverse effects on plasma lipids and lipoproteins separated by density gradient centrifugation. In contrast, propranolol increased total plasma triglycerides and decreased high density lipoprotein-2 apoprotein A-I and cholesterol levels by 50% in the group of ten patients. Since low levels of high density lipoproteins have been found to be associated with an increased incidence of coronary artery disease, the data obtained suggest that propranolol may induce significant, potentially atherogenic changes on lipid metabolism in hypertensive patients.

Adult↗
PubMed1986

Effects of prazosin and propranolol on blood lipids and lipoproteins in hypertensive patients.

Prazosin and propranolol were compared in an open, crossover study to determine their effects on plasma lipids and lipoproteins. After a four-week placebo period, 10 hypertensive patients were randomly assigned to prazosin treatment (Group I) and another 10 to propranolol treatment (Group II) for eight weeks. After a second four-week placebo period, treatment in each group was switched to the alternative drug for eight weeks. The mean blood pressure was reduced to normal levels (diastolic blood pressure less than or equal to 90 mm Hg) by both drugs--prazosin (1 to 8 mg per day) and propranolol (40 to 240 mg per day). The results of the study indicate that prazosin decreases serum cholesterol levels. In contrast, propranolol not only increases serum triglyceride levels and very-low-density lipoprotein cholesterol, but decreases total high-density lipoprotein cholesterol, high-density lipoprotein2 cholesterol, high-density lipoprotein2, and apoprotein A-I. The data suggest that propranolol may induce significant, potentially atherogenic changes in lipid metabolism, whereas prazosin may represent an advantageous alternative as an antihypertensive agent, especially in subjects with an already atherogenic lipoprotein profile.

Adult↗
PubMed1986

Carboplatin (NSC-241-240): an active platinum analog for the treatment of squamous-cell carcinoma of the head and neck.

Carboplatin (CBDCA, Bristol-Meyers, New York) is a second generation platinum analog. Preclinical and phase I clinical studies have indicated a different spectrum of toxicity compared with the parent compound. In order to study the activity of carboplatin against cancer of the head and neck, 31 patients with recurrent or metastatic disease (30 squamous-cell and one adenoid cystic carcinoma) were treated with doses of 60 to 80 mg/m2 administered daily by intravenous (IV) bolus injections for five days, repeated at every 4- to 5-week intervals. In most cases, treatment was administered on an outpatient basis. Eight patients (26%; 95% confidence interval, 12% to 45%) had complete (CR) or partial responses (PR) with a median duration of 4.5 months. Moderate bone marrow suppression was the main toxicity. Mild nausea and vomiting was unusual and no neuro- or nephrotoxicity were seen. These preliminary data suggest that carboplatin has activity against advanced squamous-cell carcinoma of the head and neck comparable with the results reported with cisplatin alone in similar patient populations. The potential advantages over the parent compound relate to the absence of nephrotoxic effects and mild gastrointestinal toxicity which allows for outpatient treatment. Because carboplatin toxicity is directly dependent on its mechanism of renal excretion, particular attention should be given for its use in patients with impaired renal function or when combined with nephrotoxic agents. Similarly, because the dose limiting toxicity with this agent is primarily hematologic, its use in combination with other myelotoxic agents should be carefully undertaken. Further studies are indicated in order to define the spectrum of activity of the new generation platinum analogs in various tumors in humans.

Adult↗
PubMed1985

Effects of prazosin and alphamethyldopa on blood lipids and lipoproteins in hypertensive patients.

The effects of prazosin and alphamethyldopa on blood lipids and lipoproteins were assessed in 20 patients with mild or moderate arterial hypertension. Parameters measured included serum cholesterol (CHO), triglycerides (TG), high density lipoprotein-cholesterol (HDL-CHO), insulin (I), glucose (G), and non-esterified fatty acids (NEFA). Prazosin -4 mg/day for 6 weeks in hydrochlorothiazide-treated patients lowered blood pressure by 18.6/17.2 (systolic/diastolic pressure) mmHg. There was a significant decrease in CHO (-5.8%), in I (-16.5%), and in NEFA (-3.0%), and a significant increase in HDL-CHO (+15.5%). Alphamethyldopa 250-750 mg/day for 6 weeks in hydrochlorothiazide-treated patients lowered blood pressure by 18.8/14.6 (systolic/diastolic pressure) mmHg, accompanied by a non-significant decrease in CHO and TG, and significant increases in HDL-CHO (+10.3%), G (+8.5%) and NEFA (+6.4%). Thus, prazosin appears to have a more beneficial effect on blood lipids and lipoproteins than alphamethyldopa.

Adult↗
PubMed1985

Haemodynamic effects of enalapril, a new converting enzyme inhibitor, in hypertensive patients.

The haemodynamic effects of enalapril (EN), a new, long-acting, nonsulphhydryl converting enzyme inhibitor, were evaluated by non-invasive methods in 10 adult patients with mild to moderate essential hypertension (EH). Patients were randomly assigned, double blind to 2 treatment groups (EN 20 mg o.d. or 10 mg b.d.) for 4 weeks, and were crossed over to the other dosage regimen after a 2-week washout period. Measurements included mean arterial pressure (MAP), heart rate (HR), cardiac output (CO), limb blood flow (LBF), plasma aldosterone (ALD), plasma renin activity (PRA) and systolic time intervals (STI). Both regimens (b.d. and o.d.) significantly reduced MAP (15.3% and 16.3%, respectively), total peripheral resistance (20.3% and 21.8%, respectively), limb vascular resistance (24.1% and 24.9%) and ALD (33.5% and 36.9%) and increased CO (7.8% and 8.7%), LBF (10.9% and 11.6%) and PRA (10.4% and 9.5%). No significant change was observed in HR or STI. EN 20 mg o.d. or 10 mg b.d. reduced arterial pressure to a similar extent through a fall in total peripheral resistance. An increase in CO was also observed.

Adult↗
PubMed1983

Cardiovascular hemodynamic interactions between clonidine and minoxidil in hypertensive patients.

The systemic, cardiovascular hemodynamic and biochemical interactions between clonidine and minoxidil were studied in ten patients with refractory and/or accelerated hypertension. Clonidine in oral doses of 150 to 900 micrograms/day decreased mean blood pressure (MAP) 18.6 mm Hg (p less than 0.01), average heart rate (HR) 16.4 bpm (p less than 0.01), limb blood flow 1.63 ml/100 g min (p less than 0.05), plasma renin activity (PRA) 1.13 ng/ml/hr (p less than 0.025), and urinary noradrenaline excretion rate 16.45 micrograms/24hr (p less than 0.05). Clonidine increased the preejection period index (PEPI) 12.4 msec ( p less than 0.001), but did not alter cardiac index (CI), total peripheral resistance index (TPRI), limb vascular resistance nor dopamine beta-hydroxylase activity. When minoxidil in oral doses of 5 to 22.5 mg was added, a further decrease in MAP of 24.2 mm Hg (p less than 0.01) was observed; PEPI decreased 20.6 msec (p less than 0.01), limb blood flow decreased 13.2 mm Hg/min 100 g/ml (p less than 0.05), and total peripheral resistance index decreased 13.3 mm Hg/min m2/L (p less than 0.05). Minoxidil increased average heart rate 8.2 bpm (p less than 0.05), PRA 1.68 ng/ml/hr (p less than 0.05) and urinary noradrenaline excretion rate 5.0 micrograms/24 hr (p less than 0.01). Limb blood flow, cardiac index and dopamine beta hydroxylase activity were not significantly altered by minoxidil. Neither clonidine nor minoxidil affected cardiovascular responses to treadmill exercise. We concluded that clonidine is a useful alternative agent to block a minoxidil-induced increase in sympathetic nervous activity.

Adult↗
PubMed1983

Eye-banks.

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Corneal Transplantation↗
PubMed1982

Effect of prazosin on blood lipids and on thyroid function in hypertensive patients.

Nineteen patients with essential hypertension (EH) were studied as outpatients. After administration of chlorthalidone, 50 mg/day for 4 weeks, prazosin 1-4 mg/day (1.82 +/- 0.33 mg/day) was added for a period of 12 weeks. Prazosin lowered supine blood pressure from 149.7 +/- 2.85/102.0 +/- 2.75 mm Hg to 128.2 +/- 3.0/86.1 +/- 1.04 mm Hg (p less than 0.001). Prazosin did not alter heart rate significantly. Prazosin increased the thyroid stimulating hormone (TSH) from 3.63 +/- 0.33 microunits/ml to 4.83 +/- 0.45 microunits/ml (p less than 0.025), thyroxine (T4) from 10.03 +/- 0.29 micrograms/ml to 10.85 +/- 0.42 micrograms/ml (p less than 0.005), and decreased triiodothyronine (T3) from 36.65 +/- 0.62% to 35.42 +/- 0.56%, which was not significant. The free thyroxine index (FTI) increased slightly from 3.67 +/- 0.12 to 3.83 +/- 0.14 (p less than 0.025). However, all values remained within the normal range for the laboratory. Serum cholesterol increased insignificantly. Triglycerides decreased significantly from 223.4 +/- 50.6 mg/dl to 161.7 +/- 29.0 mg/dl (p less than 0.05). High density lipoproteins (HDL) increased significantly from 30.1 +/- 2.1% to 36.0 +/- 3.06 (p less than 0.025). Low density lipoproteins (LDL) decreased insignificantly and very low density lipoproteins (VLDL) decreased from 20.9 +/- 3.44 to 16.3 +/- 2.85 (p less than 0.005). The cholesterol ratio increased from 45.51 +/- 4.3 to 64.71 +/- 10.7 (+42.1%). These results indicate that, in patients with essential hypertension, prazosin is an effective antihypertensive agent and that it significantly increases HDL, decreases VLDL, and improves the cholesterol ratio.

Adult↗