Age and the cardiovascular system.
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Adult↗
Biomedical subjects
J Y Wei
Publications and source records attributed to J Y Wei.
A new technique for simultaneous monitoring of electrocardiogram and walking cadence.
A new technique for simultaneously recording continuous electrocardiographic (ECG) data and walking step rate (cadence) is described. The ECG and gait signals are recorded on 2 channels of an ambulatory Holter monitor. Footfall is detected using ultrathin, force-sensitive foot switches and is frequency modulated. The footfall signal provides an indication of the subject's activity (walking or standing), as well as the instantaneous walking rate. Twenty-three young and elderly subjects were studied to demonstrate the use of this ECG and gait recorder. High-quality gait signals were obtained in all subjects, and the effects of walking on the electrocardiogram were assessed. Initial investigation revealed the following findings: (1) Although walking rates were similar in young and elderly subjects, the elderly had both decreased heart rate (HR) variability (p < 0.005) and increased cadence variability (p < 0.0001). (2) Overall, there was an inverse relation between HR and cadence variability (r = -0.73). Three elderly subjects with no known cardiac disease had HR and cadence variability similar to those of the young, whereas elderly subjects with history of congestive heart failure were among those with the lowest HR variability and the highest cadence variability. (3) Low-frequency (approximately equal to 0.1 Hz) HR oscillations (frequently observed during standing) persisted during walking in all young subjects. (4) In some subjects, both step rate and HR oscillated at the same low frequency (approximately equal to 0.1 Hz) previously identified with autonomic control of the baroreflex.(ABSTRACT TRUNCATED AT 250 WORDS)
Adult↗
Management of acute myocardial infarction in the very elderly.
Coronary artery disease is highly prevalent among the elderly, and the incidence of myocardial infarction (MI) is high. Still, the notion of optimal treatment for the elderly patient with MI remains unclear. This review will first discuss some of the characteristics of the aging myocardium that impact on the care of elderly cardiac patients. Next, the therapeutic options and their appropriateness for the aged patient are presented. Thrombolytic and beta-blocker therapies are reviewed extensively since they remain among the controversial issues in geriatric cardiology. Other well-known as well as experimental therapies are also discussed.
Aged↗
Sources of anterior gastric vagal efferent discharge in rats: an electrophysiological study.
The source of vagal efferent discharge (VED) in the anterior branch of the gastric vagus was investigated in urethane-chloralose anesthetized rats using successive and selective vagal cuts. After cutting the right cervical vagus, the basal VEDs were increased in 15 out of 21 cases by 4-53% (median 18%). After both cervical vagi were cut, VEDs were reduced by 10-95% (median 90%) in 14 of 17 experiments and a subcervical basal VED was observed in all rats. Additional cut of the distal end of the anterior gastric branch did not induce a consistent effect. A small segment of subdiaphragmatic anterior gastric vagus (4-5 mm) was further isolated by a fourth cut at the proximal end of the anterior gastric vagus; abolition of the subcervical VED occurred in only 4 of 14 successful cuts whereas in the other 10 experiments, the VED was reduced by 38-94% (median 87%). Histological examination revealed the presence of neurons in a paraganglion lying within the isolated nerve segment. These findings indicate that the stomach not only receives VED descending directly from medullary vagal motor neurons (about 90%), but also (approximately 10%) from neural elements located between subcervical to upper abdomen levels (the 'subcervical VED') and/or between the bifurcation of the accessory celiac branch to the gastro-esophageal junction (the 'residual VED'). In rats there is little crossed gastric vagal innervation, in agreement with anatomical observations, although there is a robust inhibitory influence from contralateral vagal afferents on medullary vagal motor neurons.
Animals↗
Enhanced left ventricular diastolic filling associated with long-term endurance training.
Normal aging is associated with an impairment in early left ventricular diastolic filling. To test the hypothesis that long-term endurance exercise training is associated with enhanced ventricular diastolic filling indices, we compared transmitral pulsed Doppler inflow spectra in healthy young adults; healthy elderly, sedentary subjects (sedentary old); and healthy elderly, endurance athletes (master athletes). Our data demonstrate that, despite an increase in left ventricular mass, early diastolic filling was enhanced in master athletes compared to the sedentary old. Blood pressure of both master athletes and the sedentary olds was greater than the young adults, but the higher blood pressure did not correlate to changes in filling parameters. Resting systolic function and heart rate were not significantly different in all three different groups. Early left ventricular filling indices in master athletes more closely resemble transmitral inflow patterns of healthy young adults. Long-term endurance exercise is associated with physiologic hypertrophy and ventricular filling dynamics more characteristic of the young than the old.
Adult↗
DNA repair and Alzheimer's disease.
The accumulation of nonrepaired or misrepaired DNA lesions, induced by exogenous and/or endogenous DNA-damaging agents, has been postulated to be one of the major and fundamental causes of aging. The accumulation of DNA damage might lead to changes in the expression of genes important for cell survival and, as such, could be a relevant risk factor in the etiology of various age-related diseases, including neurodegenerative diseases. This review deals specifically with Alzheimer's disease (AD) and the proposed role of defective DNA repair in the etiology of this disease. The evidence that a genetic defect in some aspect of base excision repair is present in cells from AD patients is discussed. Based on the available data, it seems justified to conclude that in at least the familiar form of the disease such a DNA repair defect is present in fibroblast and lymphoid cells. The absence of sufficiently efficient DNA repair mechanisms, involved in the removal of small base damages in the brain, could result in the accumulation of misrepaired or nonrepaired DNA damage and might ultimately lead to the neuronal degeneration as observed in AD patients. In this respect, the existence of inherently imperfect DNA repair processes in longer-lived species, such as mammals, might be regarded as a trade-off between reproductive success and cellular maintenance and repair, which would lead to a high level of DNA damage and mutation at old age.
Aging↗
PTCA in the elderly: the "young-old" versus the "old-old".
OBJECTIVE: To evaluate the use of percutaneous transluminal coronary angioplasty (PTCA) in elderly coronary artery disease (CAD) patients. DESIGN: A prospective study of patients 60 years and older undergoing de novo PTCA. We analyze patient risk factors, underlying disease, and clinical outcomes, with at least 3-year follow-up. Comparisons between different age strata among these patients are made to clarify differences between the young old (60 to 69 years), the middle old (70 to 79 years), and the very old (80 years and older). SETTING: Beth Israel Hospital, Boston, both a primary care and tertiary care teaching hospital. PATIENTS: 907 consecutive elderly cardiac patients referred for PTCA are studied. INTERVENTIONS: PTCA's were completed using the newest catheter technologies as they became available. All patients were premedicated with aspirin and dipyridamole, and all were anticoagulated with heparin. RESULTS: Subdivision by age demonstrates that the majority (67%) of patients aged 60 to 69 were males, but females were preponderant (61%) in those aged 80 and older. Octogenarians also had lower incidence of hypercholesterolemia, tobacco use, and family history of CAD, and a higher frequency of CHF, angina, and previous MI. Although total procedure-complications increased with age, critical complications (MI, reocclusion, CABG, death) did not. Primary procedural success was similar in all age strata, but older patients had a higher prevalence of multi-vessel disease and longer hospital stay. Follow-up shows that most patients did well after PTCA; there was no increase in repeat PTCA, CABG, and MI with age. CONCLUSIONS: While advanced age is associated with changes in risk and clinical parameters for CAD patients, age alone is not a reasonable criterion to limit the use of PTCA.
Age Factors↗
Age-related differences in the expression of proto-oncogene and contractile protein genes in response to pressure overload in the rat myocardium.
Cardiac adaptation to hemodynamic stress involves both quantitative (hypertrophy) and qualitative (pattern of gene expression) changes. Our previous studies have shown that advancing age in the rat is associated with diminished capacity to develop left ventricular hypertrophy in response to either ascending aortic constriction (AoC). In this study, we examined whether the expression of protooncogenes and contractile protein genes in response to AoC differs between adult (9-mo-old) and old (18-mo-old) rats. RNA was isolated from the left ventricles of AoC animals of both age groups subjected to a similar hemodynamic stress. Immediately after AoC, the levels of the ventricular expression of c-fos and c-jun protooncogenes were markedly lower in the old rats than in the adult animals. 5 d after the operation, the ratio of beta- to alpha-myosin heavy chain mRNAs increased significantly after AoC in both age groups. In contrast, AoC was associated with a marked reduction in the levels of mRNAs encoding sarcoplasmic reticulum Ca(2+)-ATPase (by 69%) and cardiac calsequestrin (by 49%) in the old rats but not in the adults. The mRNAs encoding atrial natriuretic factor and skeletal alpha-actin increased in response to AoC only in the adult rats. There were no significant differences in expression of the cardiac alpha-actin mRNA among the experimental groups. These data suggest that (a) the expression of protooncogenes in response to acute pressure overload is significantly reduced in the aged rats and (b) the pattern of expression of the contractile protein gene in response to AoC in the old rats differs qualitatively as well as quantitatively from that in younger animals. These age-related differences may play a role in the higher frequency of heart failure in the aged during hemodynamic stress.
Actins↗
Effects of relative hypoxia and hypercapnia on intracellular pH and membrane potential of cultured carotid body glomus cells.
Clusters of glomus cells, isolated from rat carotid bodies, were cultured for up to 2 weeks. Afterwards, we simultaneously measured the intracellular pH (pHi) and membrane potentials (Em) of single cells with pH-sensitive and KCl-filled microelectrodes. In 89 control cells (bathed in saline equilibrated with 50% O2 in N2) pHi was 6.87 +/- 0.014 (SE) and Em -36.3 +/- 0.45 mV. In 42 cells, switching to air (about 20% O2) lowered pHi in 60% of them by as much as 0.14 unit (mean decrease, 0.05). In the remaining cells, pHi increased by as much as 0.18 unit (mean increase, 0.06). Application of 2.5% CO2 in 50% O2 (balance N2) reduced the pHi in 90% of 47 cells by as much as 0.44 unit (mean decrease, 0.14). pHi increased to a maximum of 0.05 unit (mean increase, 0.04) in the others. Either stimulus depolarized or hyperpolarized glomus cells (-5 to 8 mV) in approximately equal proportions. There was a significant and positive correlation between delta Em and delta pHi. This observation confirms the idea that the Em of glomus cell is H(+)-dependent. Results do not agree with the acidic hypothesis for chemoreception.
Animals↗
Comparison of differences in the hemodynamic response to passive postural stress in healthy subjects greater than 70 years and less than 30 years of age.
To test the hypothesis that age-related increases in arterial pressure alter the cardiovascular response to physiologic stress, 9 healthy elderly volunteers (74 +/- 2 years) and 7 young subjects (27 +/- 3 years) were subjected to a standard 60 degrees upright tilt. Cardiac volumes were measured with patients in the supine position and 5 minutes after they assumed an upright posture using radionuclide ventriculography, while heart rate, blood pressure and forearm cutaneous flow were recorded continuously and simultaneously. Only the expected age-related increase in mean arterial pressure (young subjects, 79 +/- 1 mm Hg; elderly subjects, 99 +/- 3 mm Hg; p less than 0.001) distinguished the 2 groups at baseline. However, during upright tilt, elderly subjects had significant decreases in stroke volume (supine [108 +/- 9 ml] vs upright [78 +/- 9 ml]; p less than 0.01) and cardiac index (supine [3.4 +/- 0.2 liters/min/m2] vs upright [2.8 +/- 0.2 liters/min/m2]; p less than 0.05) because of an inability to reduce end-systolic volume (supine, 44 +/- 6 ml; upright, 51 +/- 7 ml); however, mean arterial pressure was maintained through an increase in peripheral resistance. In contrast, the young relied solely on cardiac adaptations to postural stress by decreasing end-systolic volume (supine, 62 +/- 5 ml; upright, 39 +/- 5 ml; p less than 0.01) and increasing heart rate (57 +/- 2 min-1 to 71 +/- 3 min-1, p less than 0.01), whereby cardiac output and mean arterial pressure were maintained during tilt.(ABSTRACT TRUNCATED AT 250 WORDS)
Adult↗
Intracellular pH and some membrane characteristics of cultured carotid body glomus cells.
Clusters of carotid body (glomus) cells cultured from a few days to 3 weeks, maintained their morphological characteristics during this period. The resting potential (Em) and input resistance (Ro) did not change for 2 weeks but both declined afterwards. The intracellular pH (pHi) of glomus cells, measured with glass microelectrodes filled with an H+ ion exchanger, was 6.34-6.96 at extracellular pH (pHo) of 7.32-7.53. Changes in pHo from normal to about 5.5 depolarized most cells but the fall in pHi was less marked than predicted by the Nernst equation. Conversely, shifting pHo to 8.5 hyperpolarized the cells with an increase in pHi which was more acid than predicted. EH (the calculated equilibrium potential for H+ (Nernst equation) was more positive than Em during acidity and more negative during normal or alkaline pHo. The kinetics of H+ ion distribution was assessed by brief exposures to NH4Cl. It is concluded that hydrogen ions are not passively distributed across the glomus cell membranes and that Em is dependent on H+ ions.
Ammonium Chloride↗
Reversal of changes in left ventricular diastolic filling associated with normal aging using diltiazem.
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Adult↗
Central and peripheral actions of calcitonin gene-related peptide on gastric secretory and motor function.
CGRP exerts a potent central action to inhibit gastric acid secretion in rats and dogs and gastric emptying, contractility and ulcer formation in rats. The site of action to inhibit acid secretion has been localized in the dorsal vagal complex. The inhibition of acid secretion is related primarily to the decrease in vagal efferent activity whereas the inhibition of gastric motor functions involves increases in sympathetic outflow. The central action of CGRP to prevent ethanol-induced lesions is unique to this peptide and not shared by other centrally acting inhibitors of gastric function. It may be related to the increase in gastric mucosal blood induced by central CGRP. The presence of CGRP-like immunoreactivity and receptors in medullary nuclei receiving visceral information and influencing vagal outflow suggests a possible role of the peptide in the vagal regulation of gastric secretion. Peripheral injection of CGRP also inhibits acid secretion when administered peripherally in rats, dogs, rabbits and humans. Its antisecretory effect is unlikely to be related to a direct action on the parietal cells. It involves specific and marked release of gastric somatostatin through an interaction with CGRP receptors characterized on D cells and coupled with cAMP. In addition, CGRP induces a decrease in acetylcholine transmission in the enteric nervous system which may contribute to the inhibition of acid. Peripheral CGRP inhibits gastric emptying and motility by a direct action on smooth muscles through receptors linked with cAMP. The release of CGRP from spinal afferents innervating the stomach in response to stimulation of capsaicin-sensitive fibers suggests a role of the peptide in the regulation of gastric function.
Animals↗
Long-term follow-up of patients aged 75 years and older admitted to an acute care hospital in Israel.
Certain biomedical and psychosocial factors may be important in predicting short-term and long-term outcomes in elderly inpatients in an acute care hospital. We prospectively studied all patients aged 75 years and older who were admitted to an acute inpatient geriatrics unit between June, 1984 and May, 1985, and we followed them for 5 years. Patients were followed by phone and/or the outpatient ambulatory service; follow-up visits occurred at 4 to 6 weeks following discharge and annually thereafter. After 5 years, 21% of the patients were alive. Apparently, age and gender were the major parameters associated with prognosis. Functional status and nutritional state (body weight, serum albumin) were also important prognostic factors. Of the geriatric syndromes, urinary incontinence seemed to be most strongly associated with a poor outcome, followed by falls and confusion. Iatrogenic conditions apparently had no such association. These findings suggest that certain demographic and clinical factors may be useful prognosticators for elderly hospitalized patients.
Aged↗
Influence of age and dose on the end-organ responses to atrial natriuretic peptide in humans.
To test the hypothesis that age differentially affects the natriuretic, hemodynamic, and humoral response to exogenous ANP, we studied seven young (Y, 20 to 39 years) and five old (O, 65 to 83 years) healthy, normotensive, nonobese men during infusion of synthetic human ANP1,28 at two different rates: 1) 0.05 microgram/kg/min (high dose) for 1 h and 2) 0.005 microgram/kg/min (low dose) for 1 h. Compared to young, the old had higher basal ANP levels (O = 142 +/- 41 v Y = 29 +/- 4 pmol/L, P less than .025), achieved higher plasma levels with low-dose infusion (O = 327 +/- 24 v Y = 155 +/- 37 pmol/L, P less than .001) and had a longer ANP half-life (O = 7.8 +/- 0.6 v Y = 4.3 +/- 0.6 min, P less than .001), suggesting decreased catabolism in the old compared to the young. Despite these age-related differences in ANP levels, there was no difference in urinary sodium or cyclic GMP excretion. After termination of the low-dose infusion, plasma ANP and urinary cGMP promptly returned to baseline levels. Despite this, a sustained natriuresis (2-fold above control) was observed for 3 h in both groups. Low-dose infusion was associated with sustained suppression of aldosterone with minimal hemodynamic changes. During high-dose infusions there was no difference in natriuresis or peak ANP levels between the two groups (O = 1299 +/- 93 v Y = 1140 +/- 54 pmol/L). In contrast to the low-dose infusion, the high-dose infusion produced a transient natriuresis lasting only for the duration of the infusion.(ABSTRACT TRUNCATED AT 250 WORDS)
Adult↗
The use of estrogen to decrease aggressive physical behavior in elderly men with dementia.
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Aged↗
Response of cat ventrolateral spinal axons to an itch-producing stimulus (cowhage).
A comparison was made between different categories of mechanically sensitive, ventrolateral spinal axons to assess their sensitivity to the itch-producing substance cowhage. Of 52 wide-dynamic-range (WDR) units, 17 had contralateral, 22 had ipsilateral, and 13 had bilateral receptive fields. Of the 5 low-threshold units, 1 had an ipsilateral receptive field and the remainder were bilateral. Among the high-threshold units, 10 were contralateral, 6 ipsilateral, and 5 bilateral. Although there was no evidence of cowhage sensitivity in either low- or high-threshold spinal axons, neurons with WDR properties were reactive to cowhage. WDR neurons were subclassified on the basis of their resting discharge pattern as having intermittent, continuous, or no resting discharge. WDR units with an intermittent pattern of resting discharge demonstrated a significant sensitivity to active cowhage and hence might be regarded as pruritogen-responsive spinal axons. Inactive cowhage was used as a control stimulus. In some WDR units with large receptive fields, there were observations suggesting convergence of chemoreceptive and mechanoreceptive inputs, which produced inhibitory as well as excitatory effects.
Afferent Pathways↗
Personal computer interface and software for the ZONAX microscope attachment controller.
We describe the hardware and software of a general-purpose interface that permits a personal computer (PC) running MS-DOS to control cytometric devices, e.g., a scanning stage, shutters, and focus motor attached to a microscope. This note explains how to use the interface to convert the ZONAX microscope attachment controller from 8080-based hardware control to PC-based control.
Computer Peripherals↗