Search PubMed⌕ Search

Biomedical subjects

N Winer

Publications and source records attributed to N Winer.

54 records · Page 3Linked to original sources
PubMed1982

Effects of pindolol and methyldopa on blood pressure and plasma norepinephrine.

Thirty patients with essential hypertension (supine diastolic blood pressure 100 to 115 mm Hg) were treated in a randomized, double-blind study with either pindolol (mean dose 28 +/- 5 mg twice a day) or methyldopa (673 +/- 158 mg three times a day) for 12 weeks after a 3-week, single-blind placebo period. In 17 pindolol-treated patients mean supine blood pressure was 163 +/- 3/106 +/- 1 during the placebo period and 155 +/- 3/99 +/- 2 mm Hg (p less than 0.01) during the high-dose period. In 13 patients treated with methyldopa mean supine blood pressure fell from 160 +/- 4/104 +/- 1 to 156 +/- 5/97 +/- 2 mm Hg. Mean standing heart rate was reduced during pindolol therapy from 84 +/- 2 to 79 +/- 2 bpm (p less than 0.05) but was unchanged during methyldopa treatment. Mean supine pretreatment plasma norepinephrine fell from 379 +/- 40 to 337 +/- 33 pg/ml in patients on pindolol therapy and from 448 +/- 76 to 223 +/- 39 pg/ml (p less than 0.02) in the methyldopa-treated group. Although norepinephrine generally decreased in pindolol responders and not in nonresponders, changes in supine diastolic blood pressure and supine plasma norepinephrine did not correlate. In contrast, norepinephrine declined consistently in methyldopa-treated patients regardless of the blood pressure response; changes in diastolic blood pressure and norepinephrine correlated (r = 0.59; p less than 0.05). The results suggest that suppression of sympathetic nervous system activity may play a role in the hypotensive effect of both pindolol and methyldopa.

Blood Pressure↗
PubMed1981

Kinetics of aspirin, salicylic acid, and salicyluric acid following oral administration of aspirin as a tablet and two buffered solutions.

Twelve fasting normal volunteers received three aspirin dosage forms in a single-dose, complete crossover study; the plasma and urine levels of aspirin, salicylic acid, and salicyluric acid were measured for 10 hr. The three dosage forms were an unbuffered tablet, an effervescent solution with 16 mEq of buffer, and an effervescent solution with 34 mEq of buffer. Significant differences in the absorption rate were observed, with the solution having 16 mEQ of buffer being fastest, the solution having 34 mEq of buffer being intermediate, and the tablet being slowest. These differences are attributed to gastric emptying rates and tablet dissolution. Urine pH and renal clearance for all three acid compounds are influenced by the buffer during the first 2 hr following dosing but not later. Area under the curve comparisons suggest that approximately 20% more aspirin reaches the general circulation intact following the tablet but that the total amount of salicylate absorbed is not different. Further studies are required to select the optimal buffer content to provide rapid absorption with minimal sodium dose and urine alkalinization.

Absorption↗
PubMed1980

Effect of exercise on renal clearance of atenolol.

The effect of exercise on plasma atenolol was evaluated using a two-phase complete crossover study in 12 healthy volunteers. In one phase, the volunteers were subjected to physical exertion on a treadmill; in the other phase, they remained in a sitting or standing position. Following a single 100-mg atenolol dose, frequent blood samples and a complete urine collection were obtained over 24 hr. Plasma and urine atenolol levels were assayed by high-pressure liquid chromatography. Plasma atenolol was significantly (p less than 0.05) higher during the exercise phase of the study, and this result was associated with approximately an 8% decrease in the renal clearance of the drug, probably due to decreased renal blood flow during exercise.

Adult↗
PubMed1979

Kinetics and absolute bioavailability of atenolol.

Twelve healthy volunteers received four single doses of atenolol (25-, 50-, and 100-mg oral solutions and a 50-mg intravenous infusion), each dose separated by at least one week. Blood and urine assayed for atenolol by a high pressure liquid chromatography (HPLC) method. Kinetic analysis of the intravenous data indicates a three-compartment model with elimination from the central compartment. The mean (+/- SD) terminal elimination half-life is 6.06 +/- 2.02 hr, the mean volume of the central compartment is 0.173 L/kg, and 94.1 +/- 8.0% of the intravenous dose is excreted in the urine. The mean value of the plasma clearance is 10.7 +/- 1.27 L/hr and of the renal plasma clearance, 10.4 +/- 1.14 L/hr. The mean absolute bioavailability for the 25-, 50-, and 100-mg oral doses is 0.52 +/- 0.18, 0.54 +/- 0.12, and 0.58 +/- 0.16, respectively. The maximum plasma concentration varies as a linear function of dose. Time to mean maximum plasma concentration (3.0 hr) and the time for half of the bioavailable dose to be absorbed (2.0 hr) do not differ significantly with dose. The mean renal plasma clearance after oral doses (9.49 +/- 1.6 L/hr) is in the same range as renal clearance after intravenous doses.

Adult↗
PubMed1976

Pharmacokinetics of oxprenolol in normal subjects.

The effect of oxprenolol administered intravenously (10 and 20 mg) and orally (20, 40, 80, and 160 mg) on plasma concentrations of the drug, resting heart rate, exercise-induced tachycardia, and arterial blood pressure was assessed as a function of time in 6 healthy subjects. The pharmacokinetics of oxprenolol following intravenous administration are best described as 2-compartnent open model with dose-dependent parameters. The mean (+/-SD) plasma half-life for oral doses is 1.94 +/- 0.37 and for intravenous doses is 2.31 +/- 0.64 hr. After oral administration, peak plasma concentrations are reached within 30 to 90 min, and the area under the plasma concentration-time curve varies linearly with the dose. Comparison of oral and intravenous data reveals the variation in bioavailabilty of orally administered oxprenolol to range from 19% to 74%. Unlike propranolol, oxprenolol does not show a saturable "first-pass" elimination effect. Blockade of beta-receptors occurs at plasma levels in excess of 60 ng/ml as evidenced by significant reductions in resting heart rate and exercise-induced tachycardia. Higher plasma concentrations of oxprenolol are required to lower blood pressure compared to those necessary to slow heart rate. These data suggest significant pharmacokinetic differences between oxprenolol and other beta-adrenergic receptor antagonists.

Administration, Oral↗
PubMed1975

The differentiation of primary hyperparathyroidism from the hypercalcemia of malignancy.

The presence of hypercalcemia in patients with known cancers may be due to the cancers themselves, or to co-existing primary hyperparathyroidism. The differentiation of primary hyperparathyroidism from the hypercalcemia of malignancy is important since the relief of distressing symptoms and prevention of hypercalcemic crises and renal failure can be accomplished relatively easily by parathyroid surgery in the former condition, and only with difficulty, at times, with fluids and drugs in the latter condition. The histories of three recent patients are presented, which demonstrate the difficulties inherent in the differentiation of these conditions. These patients were ultimately found at operation to have primary hyperparathyroidism in addition to malignancies of the cervix, adrenal gland and kidney. In our experience the following have been helpful in establishing a diagnosis; history of hypercalcemia prior to development of cancer, the type of cancer itself, the effect of cancer therapy on the hypercalcemia, and selective venous sampling with radioimmunoassay for parathyroid hormone.

Adrenal Gland Neoplasms↗
PubMedDate not supplied

Gender differences in vascular compliance in young, healthy subjects assessed by pulse contour analysis.

OBJECTIVES: Sex hormones exert important effects on the vasculature. Female sex hormones have been reported to enhance endothelial function, reduce oxidative stress, and protect against atherosclerosis. However, the effects of estrogen on vascular compliance have not been studied. Recently, noninvasive instrumentation that estimates vascular compliance by recording the radial artery pulse contour has been introduced. Reductions in the oscillatory or reflected component of the diastolic waveform have been observed in various clinical conditions, including hypertension, diabetes mellitus, and congestive heart failure, and may reflect endothelial dysfunction at the site of resistance vessels. In this study the authors examined gender-related vascular compliance in a cohort of young, healthy, predominantly nonsmoking, medication-free men and women to determine the influence of cardiovascular risk factors, including family and social history, serum lipids, plasma homocysteine, and insulin levels on vascular compliance. METHODS: The volunteers, consisting of 151 healthy men and women (mean age 24A+/-4 years) completed a questionnaire detailing family and social history, medication use, and exercise habits. Large (C1) and small (C2) vessel compliance and various cardiovascular parameters were derived from arterial pulse wave contour analysis. Systolic, diastolic, and mean arterial blood pressure, pulse pressure, and pulse rate were determined simultaneously by oscillometry. Blood for fasting serum lipids, plasma homocysteine, and serum insulin were obtained in a subset of 135 subjects. RESULTS: The questionnaire revealed that 38% of parents had a history of hypertension, 31% had dyslipidemia, and 15% had coronary heart disease. C2 was lower in subjects with parental dyslipidemia. Compared to men, women had lower C2; lower systolic blood pressure, mean arterial pressure, and pulse pressure; higher serum high-density lipoprotein cholesterol; lower serum triglycerides; and lower plasma homocysteine, but similar serum insulin levels. C1 correlated with height and pulse pressure, whereas C2 was proportional to height and weight and inversely related to systemic vascular resistance. Multivariate regression analysis showed that stroke volume, total vascular impedance, cardiac output, female gender, and systemic vascular resistance independently predicted changes in C2, but that height was not a significant factor. CONCLUSIONS: Women have reduced C2 despite lower systolic blood pressure and pulse pressure and more favorable lipid and homocysteine levels. C2 is independent of height and is lower in subjects with parental dyslipidemia. These data indicate that female sex hormones have unexpected negative effects on small vessel compliance. They may help to explain why premenopausal women hospitalized for myocardial infarction have higher mortality rates than men of the same age.

Adolescent↗
PubMedDate not supplied

Persisting spongy myocardium. A case indicating the difficulty of antenatal diagnosis.

Persisting spongy myocardium (also known as noncompaction of the ventricular myocardium) is a rare and special form of cardiomyopathy. The few cases reported in the literature were detected postnatally and involved a high rate of cardiovascular complications. This anomaly of endomyocardial morphogenesis, which occurs during the embryonic phase at the stage of cardiac partitioning, is characterised by an excessive number of prominent trabeculae and by intertrabecular recesses within the myocardial wall. Antenatal detection is difficult in the absence of an associated malformation, which is the general situation. We report a case of antenatal cardiomyopathy which led to therapeutic abortion. The diagnosis of persisting spongy myocardium was made during fetopathologic examination.

Abortion, Therapeutic↗
PubMedDate not supplied

Contribution of tridimensional sonography and magnetic resonance imaging to prenatal diagnosis of Apert syndrome at mid-trimester.

A diagnosis of Apert syndrome, suspected at 24 weeks' gestation after conventional sonography showing turribrachycephaly and syndactyly of hands and feet, was confirmed at 26 weeks' gestation by tridimensional sonography and magnetic resonance imaging. This is only the second prenatal diagnosis reported at mid-trimester, excluding cases published from affected mothers or in connection with a context of recurrence. Additional findings have been collected from tridimensional sonography (mid-facial hypoplasia, downslanting palpebral fissures) and from magnetic resonance imaging (verticalization of the clivus and flattened angle of the cranial base).

Acrocephalosyndactylia↗
PubMedDate not supplied

Russell-Silver syndrome: an explanation for discordant growth in monozygotic twins.

Severe intrauterine growth retardation and suggestive dysmorphic and malformation syndrome in 1 twin with a normal karyotype during a monozygotic, monochorionic pregnancy led to the diagnosis of discordant Russell-Silver syndrome (RSS). Placental anomalies (velamentous cord insertion, single umbilical artery, placental hypotrophy) for the small-for-date twins and a twin-twin transfusion syndrome confirmed at 21 weeks of amenorrhea suggest that early hemodynamic disorders may reveal or trigger RSS which has been considered to be of genetic origin. The prognosis for RSS is favorable, except for diminished adult size (less than -2 standard deviations).

Adult↗