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Biomedical subjects

J W Rowe

Publications and source records attributed to J W Rowe.

At least 109 records · Page 6Linked to original sources
PubMed1980

Adrenergic modulation of extrarenal potassium disposal.

We studied the role of catecholamines in the regulation of potassium homeostasis in nine healthy subjects given intravenous potassium chloride (0.5 meq per kilogram of body weight) in the presence and absence of propranolol. Potassium infusion elevated serum potassium 0.6 +/- 0.09 meq per liter (mean +/-S.E.M.). Addition of propranolol augmented the rise (0.9 +/- 0.05 meq per liter) and prolonged the elevation in serum potassium without decreasing urinary potassium excretion. In a separate study, the same potassium load was administered with a concomitant infusion of epinephrine in five subjects. Epinephrine markedly blunted the increment in serum potassium (0.1 +/- 0.06 meq per liter) while reducing renal potassium excretion. Plasma aldosterone was not altered by the experimental procedures. Serum insulin fell minimally in the presence of propranolol but was unaffected by epinephrine. beta-Adrenergic blockade impairs and epinephrine enhances extrarenal disposal of an acute potassium load. These findings suggest that in patients with impaired potassium disposal, the risk of hyperkalemia may be increased when sympathetic blockade is induced.

Adrenergic beta-Antagonists↗
PubMed1980

Enhanced plasma norepinephrine response to upright posture and oral glucose administration in elderly human subjects.

Plasma norepinephrine (NE) levels in response to upright posture and to oral glucose ingestion were measured in healthy young and old (greater than 65 yr of age) subjects. Peak plasma NE concentrations with standing were higher in the elderly (1334 +/- 146 pg/ml versus 855 +/- 46; p less than 0.05) and plasma NE remained elevated in the elderly compared with the young subjects even after 15 min of recumbent resting. Following oral glucose plasma NE rose higher in the elderly (79% compared with 32% in the young) and peaked later (120 min after ingestion compared with 60 min in the young). Cardiovascular changes with upright posture and with oral glucose were similar in young and old. Alterations in disappearance of NE from the circulation could not account for the greater elevations in plasma NE concentration in the elderly either, since the rates of fall in circulating NE levels following termination of an NE infusion were the same in both groups. The metabolic clearance rate of NE was unchanged. Thus, the plasma NE responses to stimulation by standing and by oral glucose ingestion are enhanced in elderly subjects.

Adolescent↗
PubMed1980

The influence of age on peripheral lymphocyte count in men: a cross-sectional and longitudinal study.

The peripheral lymphocyte count was determined on 436 carefully screened healthy male participants of the Normative Aging Study on three successive determinations over a ten year period. Cross-sectional analysis revealed no significant differences in absolute lymphocyte count between the age groups 23 to 44, 45 to 54, and 55+ years. Longitudinal analysis also showed no significant change in absolute lymphocyte count over the study period. These results indicate that absolute lymphocyte count in healthy men does not change with age.

Adult↗
PubMed1980

Evidence in man that cigarette smoking induces vasopressin release via an airway-specific mechanism.

The plasma vasopressin response to intravenous nicotine (2 mg) and smoking cigarettes of high (1.2 mg) and low (0.6 mg) nicotine content was studied in healthy young subjects with a history of cigarette smoking. Nicotine administered intravenously had no effect on plasma vasopressin. There was a statistically significant increase in plasma vasopressin after both the low and high content cigarettes, with the high content cigarettes resulting in a significantly greater increase. All three interventions resulted in transient increases in blood pressure and pulse of similar magnitude. These studies indicate that cigarette smoking-induced vasopressin release is not mediated via an action of circulating nicotine, and suggest the presence of an airway-specific mechanism for vasopressin release.

Adult↗
PubMed1980

The influence of age, alcohol consumption, and body build on gonadal function in men.

Basal plasma levels of testosterone, dihydrotestosterone, estradiol, and gonadotropins and testosterone-binding capacity (percent radioactive testosterone bound to protein) were measured in health carefully screened young (31-44 yr old; n = 44) and older (64-88 yr old; n = 42) male participants in the Normative Aging Study of the V.A. There was no statistically significant effect of age on testosterone [younger group, 4.16 +/- 0.27 (SEM) ng/ml; older group, 4.62 +/- 0.32 (SEM) ng/ml] or the free testosterone index [younger group, 2.05 +/- 0.14 (SEM) ng/ml; older group, 1.76 +/- 0.11 (SEM) ng/ml]. The testosterone-binding capacity was higher in the older group (younger group, 50.10 +/- 1.18% (SEM); older group, 60.10 +/- 1.18% (SEM); P less than 0.001). Of the two products of testosterone metabolism studied, estradiol did not change with age, while dihydrotestosterone was lower [young group, 0.25 +/- 0.02 (SEM) ng/ml; older group, 0.20 +/- 0.01 (SEM) ng/ml; P = 0.03] in the older group. FSH levels were increased among the older men [older group, 92.9 +/- 6.0 (SEM) ng/ml; younger group, 61.1 +/- 5.0 (SEM) ng/ml; P less than 0.001]. LH levels were not significantly influenced by age. There was no effect of level of chronic stable alcohol intake on gonadal function, as estimated by testosterone levels and the free testosterone index. Analysis of the relationship between body build and hormone levels indicated that estradiol levels were highest in gynandromorphic men and lowest in mesomorphic men.

Adult↗
PubMed1979

Influence of the emetic reflex on vasopressin release in man.

The mechanisms underlying the frequent association of nausea and vomiting with elevations of plasma vasopressin(PAVP) were studied in man and rat. After oral water loads (N = 16), plasma osmolality fell in all human subjects and was associated with a decline in PAVP in 14 asymptomatic human subjects. In 2 human subjects, nausea occurred and was associated with increases in PAVP, without changes in blood pressure. During ethanol infusion (N = 28), PAVP was suppressed unless nausea supervened. In 4 nauseated human subjects, PAVP escaped from ethanol inhibition and rose to levels 10 times basal, despite the absence of hemodynamic changes. Apomorphine, a potent dopamine agonist and emetic agent, was administered to human volunteers in doses of 7 to 24 microgram/kg. There was no increase in PAVP in 3 human subjects who remained asymptomatic (7 to 16 microgram/kg). Ten human subjects experienced nausea after 16 microgram/kg, which was followed shortly by marked increases in PAVP. Emesis occurred in 5 human subjects given 16 to 24 microgram/kg, and was followed by PAVP levels similar to those seen with nausea alone. In 7 human subjects from the nausea group, the repeat study (16 microgram/kg) after pretreatment with dopamine antagonist (haloperidol, N = 4; fluphenazine, N = 3) resulted in complete blockage of apomorphine-induced AVP release. In rats, which lack an emetic reflex, apomorphine doses of 200 microgram/kg induced only slight increases in PAVP when compared to the response to 16 microgram/kg in man. These studies indicate that stimulation of the emetic reflex results in AVP-release in man. Nausea-mediated AVP release supervenes over concomitant osmolar or pharmacologic (ethanol) inhibition.

Alcohols↗
PubMed1979

Ultraviolet phototherapy of uremic pruritus. Long-term results and possible mechanism of action.

The beneficial effect of sunburn-spectrum ultraviolet (UVB) phototherapy on uremic pruritus was studied. Seven patients were treated twice weekly for 4 weeks with UVB to one half of the body and placebo phototherapy to the other half. All patients noted generalized improvement without localization of benefit to the UVB side, suggesting a systemic effect of UVB. A comparison of three schedules varying from one to three treatments weekly showed that the percentage of patients responding was not influenced by frequency of UVB exposure, although patients treated more intensively improved faster. In three patients, improvement was delayed until 2 weeks after completion of a course of six treatments over 2 weeks, indicating a delayed onset of benefit in at least some patients. Overall 32 of 38 patients improved after a course of six or eight UVB exposures. Pruritus has recurred in 15 patients after a mean remission of 3 months. Sixteen patients are known to remain in remission for a mean of at least 10.6 months after the first or second course of treatment. The present evidence indicates a systemic mechanism of action for the long-lasting relief of uremic pruritus afforded by UVB phototherapy.

Adult↗
PubMed1978

The response of arginine vasopressin to intravenous ethanol and hypertonic saline in man: the impact of aging.

The effect of age on the hypothalamic-hypophyseal-renal axis in normal man was determined by assaying plasma arginine vasopressin (AVP) responses to inhibitory and to secretory stimuli. Nine young (21-49 years) and 13 old (54-92 years) subjects received IV ethanol (375 mg/m2 per min). AVP levels fell progressively during the infusion in the young group, but fell for only 30 min in the old group and then rose paradoxically despite the continuing increase in blood ethanol. Eight young (22-48 years) and 8 old (52-66 years) men were provided identical osmolal loads by a 2-hour IV infusion of 3% NaCl at 0.1 ml/kg per min. Serum AVP rose 2.5 times the baseline in the young and 4.5 times the baseline in the old men despite identical free water clearances. Osmoreceptor sensitivity (the slope of AVP on osmolality) was greater in the old subjects. The heightened sensitivity to hyperosomolality helps examine the paradoxical response to ethanol, since osmolality increased during that time. This increased AVP response may severe to compensate for the reduced renal ability to conserve salt and water in aging man.

Adult↗
PubMed1978

Glucose intolerance in uremia. Quantification of pancreatic beta cell sensitivity to glucose and tissue sensitivity to insulin.

The relative contributions of impaired insulin secretion and of tissue insensitivity to insulin to the carbohydrate intolerance of uremia were investigated in 10 chronically uremic subjects. Two types of glucose-clamp experiments were performed in each patient before and after 10 wk of thrice weekly hemodialysis. In both types the blood glucose concentration was maintained at a constant level by the periodic adjustment of a variable glucose infusion with a negative feedback formula.Hyperglycemic clamp. The blood glucose concentration was acutely raised and maintained 125 mg/dl above basal levels for 2 h. Since the glucose concentration was held constant, the glucose infusion rate is an index of glucose metabolism (M). After dialysis M increased in all patients from an average of 4.23 to 6.30 mg/kg body wt per min (P < 0.001). The plasma insulin responses (I) both pre- and postdialysis were biphasic with an early burst within the first 2-5 min, followed by a phase of gradually increasing insulin concentration. After dialysis the plasma insulin response diminished slightly. Consequently, the M/I ratio, an index of tissue sensitivity to endogenous insulin, increased postdialysis in all subjects by an average of 92% (P < 0.01). Euglycemic clamp. The plasma insulin concentration was acutely raised and maintained by a primecontinuous insulin infusion. The blood glucose concentration was held constant at the basal level by a variable glucose infusion as above. M/I again is a measure of tissue sensitivity to insulin (exogenous) and increased in all patients postdialysis by an average of 57% (P < 0.01). In two patients hepatic glucose production was measured with tritiated glucose during the euglycemic clamp and declined by 84% predialysis. A similar decrease (82%) was observed postdialysis. Thus, both the hyperglycemic and euglycemic clamp techniques demonstrated tissue insensitivity to insulin to be the dominant carbohydrate defect in uremia. The surprising apparent lack of consistency in the change in beta cell response postdialysis is explained by the strong inverse correlation between beta cell sensitivity to glucose and tissue sensitivity to insulin (r = -0.920; P < 0.001). Those individuals who showed the most striking improvement in tissue sensitivity to insulin actually decreased their serum insulin response to hyperglycemia; those whose improvement in tissue sensitivity was more modest showed increases in beta cell responses.

Administration, Oral↗
PubMed1978

Accelerated atrioventricular conduction in Fabry's disease: a case report.

Three unrelated men with Fabry's disease (angiokeratoma corporis diffusum universale) and accelerated atrioventricular conduction are described. AQn His bundle electrogram in one patient who reported episodes of tachycardia demonstrated a prolonged deflection preceding the ventricular complex. This deflection is thought to represent an abnormal His bundle potential, possible resulting from glycolipid deposition. In the second patient the PR interval decreased from 0.18 to 0.11 second during 10 years, and in the third patient it decreased from 0.12 to 0.10 seconds during 13 years. Accelerated atrioventricular conduction may develop in Fabry's disease.

Adult↗
PubMed1977

Relief of uremic pruritus with ultraviolet phototherapy.

We studied the effect of ultraviolet-light phototherapy on severe persistent pruritus in 18 adult patients on hemodialysis. Patients were randomly assigned to one of two light sources. The experimental group received conventional sunburn-spectrum light in gradually increasing doses. The control group received time-matched exposures to long-wave ultraviolet light. All patients received eight exposures to the entire skin surface over a four-week treatment period. Nine of 10 patients in the sunburn-spectrum group reported marked decrease in pruritus as opposed to two of eight in the placebo group (P less than 0.01). of those responding to sunburn-spectrum light, improvement usually occurred two to three weeks into treatment. Mild sunburn, noted by some patients in this group, was the only side effect. The response to phototherapy was unaffected by the presence of secondary hyperparathyroidism. Ultraviolet phototherapy is a safe, convenient, inexpensive and effective treatment for uremic pruritus.

Adult↗
PubMed1977

Familial hemochromatosis: characteristics of the precirrhotic stage in a large kindred.

Ffty asymptomatic members of a kindred with familial hemochromatosis were studied in an effort to clarify some of the physiologic abnormalities present in the pre-cirrhotic or latent stage of the disease. Using excess hepatic iron as a marker for inheritance of hemochromatosis, results of liver biopsies on 31 family members suggest an auto-somal dominant mode of inheritance with incomplete expressivity. In addition to a relationship between alcohol intake and excess liver iron, there was a strong association between the level of alcohol intake and the presence of hepatic fibrosis in those subjects with excess iron stores. Both serum iron and transferrin saturation were significantly higher in family members with iron overload than in those who were not affected. Only transferrin saturation was significantly correlated with the severity of hepatic iron deposition. Studies of glucose tolerance (OGTT, IVITT, glucose clamp studies) demonstrated a defect in carbohydrate metabolism associated with deficient insulin secretion and insulin resistance, both of which were related to the degree of hepatic iron depostion. In this kindred we have found no evidence for a contribution of inheritance to the carbohydrate intolerance of hemochromatosis. Iron overload was not related to activity of hepatic collagen proline hydroxylase or urinary excretion of peptide-bound hydroxyproline. Serum ferritin, previously thought to be a reliable marker of reticuloendothelial iron stores, was normal in 19 of 20 family members with iron overload.

Adolescent↗
PubMed1976

The effect of age on creatinine clearance in men: a cross-sectional and longitudinal study.

Standard true 24-hour creatinine clearance determinations were performed on 884 subjects of the Baltimore Longitudinal Study. On the basis of clinical data, subjects were placed in categories indicating the presence of specific diseases or medications which might alter glomerular filtration rate. Subjects not included in these categories were considered normal (N=548). In the normals, cross-sectional analysis by 10-year age groups showed a progressive linear decline in clearance from 140 ml/min/1.73m2 at age 30 to 97 at age 80. Three or more serial clearances were obtained at 12- to 18-mo. intervals on 293 normal subjects. These longitudinal data showed an acceleration of the rate of decline in creatinine clearance with advancing age. The decrease in creatinine clearance with age seen in this study represents true renal aging and is not secondary to diseases which become increasingly prevalent in the elderly. A nomogram constructed from these data provides normative age-corrected standards for creatinine clearance.

Adolescent↗