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Biomedical subjects

S L Mader

Publications and source records attributed to S L Mader.

26 records · Page 2Linked to original sources
PubMed1989

Aging and postural hypotension. An update.

Postural hypotension is a common clinical problem in elderly patients. Reported studies have investigated the epidemiology and mechanisms of this disorder. However, many of these data are based on subjects with diseases and medications also known to cause this disorder, which confuses the relative contributions of normal aging, disease, and medication effects. This review critically evaluates published studies on measurement, epidemiology, and mechanisms of postural hypotension in screened and unscreened elderly populations. Pertinent age-related changes in physiology and the relationship of postural hypotension in the elderly to other models of postural hypotension are reviewed. Areas of current and future research are outlined.

Aged↗
PubMed1989

Effects of meals and time of day on postural blood pressure responses in young and elderly subjects.

Previous data suggest that postural and postprandial hypotension are common in elderly subjects. This study evaluated the effect of age, meals, and time of day on supine and standing blood pressure (BP) and heart rate in healthy young and elderly subjects. A postural BP protocol was performed on 10 young and 16 elderly subjects during an overnight stay. The protocol included first morning and postprandial readings. The systolic and diastolic BP responses to standing were not significantly different between the two groups and were not affected by time of day. Postprandial recumbent BPs declined significantly only in the older subjects. There was no effect of meals on the BP response to standing. We conclude that healthy elderly subjects have a postprandial decline in BP even when supine. However, the BP response to standing is similar in young and elderly subjects and is not impaired by overnight rest or meals. This suggests that the regulation of BP after meals and with standing may be different.

Adult↗
PubMed1988

Effect of age and posture on human lymphocyte adenylate cyclase activity.

1. A number of age-related changes have been reported in the catecholamine-adrenoceptor-adenylate cyclase system. Most of the data available on these alterations come from resting subjects; the response to acute stress may provide additional insights into the age effect on these responses. 2. We measured supine and 10 min upright plasma noradrenaline and lymphocyte adenylate cyclase activity in ten healthy elderly subjects (age 66-80 years) and seven healthy young subjects (age 27-34 years). 3. Isoprenaline stimulation of lymphocyte adenylate cyclase activity was not significantly different between supine and upright positions or between elderly and young subjects. There was a marked increase in forskolin-stimulated adenylate cyclase activity in the upright posture in both elderly and young subjects. The increment over supine levels was 70% in the elderly (P less than 0.025) and 73% in the young (P less than 0.05). This enhanced forskolin activity was not seen in two young subjects who became syncopal. 4. These data suggest that enhanced forskolin-stimulated adenylate cyclase activity occurs after 10 min of upright posture in both elderly and young subjects, and may be relevant to immediate blood pressure regulation. We were unable to demonstrate any age-related differences in these acute adrenergic responses.

Adenylyl Cyclases↗
PubMed1987

Low prevalence of postural hypotension among community-dwelling elderly.

Postural hypotension (PH) has a prevalence of about 20% in most large studies of elderly individuals; however, these studies do not exclude subjects with diseases and medications known to cause PH. We sought to determine the prevalence of PH in healthy, community-living, elderly individuals in contrast to those with known risk factors for the condition. We measured supine and one-minute standing blood pressures in 300 independently living elderly persons who visited a senior citizen health screening program. Subjects were divided into two groups: those with known risk factors (n = 175) and those without (n = 125). The prevalence of PH (systolic decrease, greater than or equal to 20 mm Hg) for for the entire population was 10.7%. In the group with risk factors, the prevalence was 13.7% (24/175), compared with 6.4% in the group without risk factors (8/125). Supine hypertension was associated with PH, but there was no relationship between the presence of PH and age, history of falls, symptoms on standing, or recent meal. These data suggest that PH is a relatively uncommon finding in healthy elderly, its prevalence is significantly related to risk factors, and its association with falls or symptoms may be less than previously reported.

Aged↗
PubMed1987

Orthostatic hypotension due to hypertrophic cardiomyopathy and autonomic failure.

A case of orthostatic hypotension due to the combination of hypertrophic obstructive cardiomyopathy and autonomic failure is described. The interacting pathophysiologic features of the two disorders and response to therapy are discussed. The value of dynamic cardiac auscultation and Doppler echocardiography in patients with postural blood pressure changes is demonstrated.

Aged↗
PubMed1984

Successful thrombolytic therapy in two patients with renal vein thrombosis.

Thrombolytic therapy was administered to two patients with angiographically documented renal vein thrombosis. One patient with bilateral thrombotic disease complicating membranous glomerulonephritis was treated with systemic streptokinase; the second patient had unilateral renal vein thrombosis associated with chronic pyelonephritis and was treated with streptokinase and urokinase administered directly into the involved vessel. Lysis of all thrombus material was demonstrated by follow-up renal venography and was associated with a gratifying improvement of clinical well-being and laboratory function. These cases demonstrate the feasibility of dissolving renal vein thrombi of presumed recent onset and suggest that rapid lysis of the thrombus accelerates functional and clinical recovery.

Drug Therapy, Combination↗
PubMedDate not supplied

Viral-mediated gene delivery of constitutively activated G alpha s alters vasoreactivity.

1. Decline in beta-adrenoceptor (beta-AR)-mediated function occurs with increasing age, as well as in multiple disease conditions. The mechanisms responsible for this decline include alterations in beta-AR itself, beta-AR coupling proteins, such as G-proteins, or other beta-AR-linked proteins, such as G-protein receptor kinases and/or phosphatases. 2. The present study examines the physiological effects of in vitro transfer of constitutively activated G alpha s (G alpha s-Q227L) to both cultured vascular smooth muscle cells (VSMC) and whole aortic tissue of 6-month-old (adult) animals via a replication-deficient Herpes simplex virus (HSV) vector. These studies were conducted to provide a model for future examination of the role of G alpha s in the age-related decline in beta-AR-mediated vasorelaxation. 3. Gene transfer was confirmed by western blotting for specific proteins. Aortic tissue infected with HSV-G alpha s-Q227L had reduced phenylephrine-induced contraction and enhanced isoproterenol-stimulated vasorelaxation. Infection of cultured VSMC with HSV-G alpha s-Q227L increased both basal- and isoproterenol-stimulated cAMP accumulation, whereas forskolin-stimulated cAMP production was unchanged. 4. These results implicate G alpha s as a target for further investigation in age-related changes in vascular reactivity and support the use of viral-mediated gene transfer as an effective tool to study adrenergic signal transduction and physiology in vascular tissue.

Animals↗