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Biomedical subjects

L B Page

Publications and source records attributed to L B Page.

At least 19 recordsLinked to original sources
PubMed1989

The Systolic Hypertension in the Elderly Program (SHEP): an intervention trial on isolated systolic hypertension. SHEP Cooperative Research Group.

The Systolic Hypertension in the Elderly Program (SHEP) is a randomized double-blind placebo-controlled trial to determine if antihypertensive treatment of isolated systolic hypertension (ISH) [systolic blood pressure (SBP) greater than or equal to 160 mmHg, diastolic blood pressure (DBP) less than 90 mmHg] reduces the 5 year incidence of fatal and nonfatal stroke. Between March 1, 1985 and January 15, 1988, 4736 persons (target 4800) with ISH, age 60 years and over, were enrolled. Potential participants met blood pressure (BP) and age criteria. Those on antihypertensive medication prior to enrollment without documented diastolic hypertension had their medication tapered and discontinued, and then met BP criteria (33% of cohort). Stepped-care therapy with chlorthalidone and atenolol (alternative, reserpine) or matching placebos was initiated as first and second steps. At baseline the trial population was 43.1% male, 56.9% female; 13.9% black, 86.1% non-black. Also, the mean age was 71.6 years; the mean SBP was 170.3 mmHg and the mean DBP was 76.6 mmHg; 59.8% had codeable resting electrocardiographic abnormalities. The trial is now in follow-up phase with scheduled termination in 1991.

Aged↗
PubMed1981

Blood pressure of Qash'qai pastoral nomads in Iran in relation to culture, diet, and body form.

Blood pressure, diet, urinary electrolyte excretion, and body form were studied in 264 traditional nomadic herdsmen of the Qash'qai tribe, southern Iran. The population sample included male and female members over 14 yr of age at six winter campsites. Interviews established biological age, any experience of nonnomadic living, and 24-h dietary recall. Height, weight, triceps skinfolds, and blood pressure were measured. Overnight urine samples were analyzed for sodium, potassium, and creatinine. Samples of dietary staples were analyzed for selected nutrients and electrolyte content. Urinary sodium excretion averaged 186 mEq/24 h in males, and 141 mEq/24 h in females. Urinary Na/K ratios were 3.64 and 3.24 in males and females, respectively. Systolic, diastolic, and mean blood pressure in both males and females increased significantly with age. Blood pressure greater than or equal to 140/90 was found in 12% of males and 18% of females age 30 yr or over. Body weight showed no tendency to increase with age in either sex. Systolic and mean blood pressure correlated with urinary sodium excretion in males and with urinary Na/K ratio in females. From cultural observations, the population sample was considered to be at a low level of acculturation. The data suggest that blood pressure trends in this population are related to habitual dietary electrolyte intake.

Adolescent↗
PubMed1978

Serial studies of the renin system in rats with glycerol-induced renal failure.

Serial changes in plasma of renin concentration (PRC), renin-substrate concentration (PSC) and renin activity (PRA) were followed in rats during glycerol-induced acute renal failure. There was an early but transient increase in PRC and a more delayed and prolonged rise in PSC. PRA began to rise a few hours after glycerol administration at the expense of increases in renin, but by 24 h the high activity was maintained largely by increases in renin-substrate. No correlations between PSC, PRC, or PRA changes and severity of renal failure could be demonstrated. These results suggest that these changes are not causally related to the development of kidney failure.

Acute Kidney Injury↗
PubMed1978

The pathogenetic significance of intravascular coagulation in experimental acute renal failure.

Serum and urine fibrin(ogen) degradation products (FDP), FDP clearances, and serum urea nitrogen (SUN) concentrations of rats challenged with glycerol-induced myohemoglobinuria were measured serially over a period of 4 days. The results obtained in animals that developed acute renal failure (ARF) were compared with those obtained in rats made refractory to renal failure by long-term salt loading or recent recovery from prior renal failure. Only the rats susceptible to ARF experienced a major rise in serum FDP concentration. Urine FDP excretion rose most markedly in the same rats but, being elevated in all groups. showed the utilization of fibrinogen whether serum FDP values increased or not. The results obtained might reflect differences in the degree of intravascular coagulation which are pathogenetically important. It is possible, however, that increased serum FDP concentrations found exclusively in rats with ARF are the results rather than the cause of impaired filtration, and that reduced tubular absorption may at least partly account for the high urinary FDP excretion observed in this model of experimental acute renal failure.

Acute Kidney Injury↗
PubMed1976

Interference by 2, 3-dimercapto-1-propanol (BAL) in angiotensin I radioimmunoassay.

The angiotensinase inhibitor 2,3-dimercaptopropanol (BAL) interferes with peptide-antibody binding when certain sensitive antisera are used in angiotensin I radioimmunoassay systems. Three of nine antisera tested showed sufficient interference to produce serious errors in data obtained using these antisera together with BAL. For PRA determinations in human plasma, at both pH 5.7 and pH 7.3, relationships between different PRA'S are altered, and results of renin stimulation tests are changed in unpredictable ways. Determination of renin concentration in rat plasma does not require use of BAL as inhibitor, and it is best avoided. For human plasma renin determinations, use of BAL-sensitive antisera should be avoided, since there is no satisfactory way to correct data for the resulting error. BAL itself, rather than its oxidation products, is probably the interfering substance. The interference appears to be due to an interaction between BAL and the BAL-sensitive antiserum. It is not related to the known actions of BAL as chelating or reducing agent.

Angiotensin II↗
PubMed1975

Methods for serial study of renin-angiotensin system in the unanesthetized rat.

Micromethods for measurement of plasma renin concentration (PRC) and plasma renin-substrate concentration (PSC) have been developed for rat plasma with radioimmunoassay of angiotensin I. An improved technique for aortic implantation of plastic cannulas was developed for use in experiments 1-2 wk in duration. The effects on components of renin system of anesthesia and tail cutting were studied. Arterial blood was sampled through cannulas without animal manipulation. PRC varied little in unanesthetized rats, was moderately and variably increased during pentobarbital anesthesia, and was markedly and consistently elevated during ether anesthesia. PSC was unchanged during anesthesia. PRC was increased in blood obtained by tail cutting within 1-2 min after cutting. With the use of the methods and techniques described here serial studies of the renin system in plasma of unanesthetized rats are shown to be feasible. A role for the sympathetic nervous system in the mediation of renin secretion by ether is proposed.

Anesthesia↗