To assess the effect of aging on left ventricular function, we performed two dimensional echocardiography at rest and during supine bicycle exercise. The study consists of 10 healthy young men (young group) and 9 healthy elderly men (elderly group), all of whom underwent submaximal treadmill stress tests with negative results. The average ages were 26.9±3.4 (mean±S.D.) and 69.4±5.5 years old. Satisfactory two dimensional echocardiographic views were obtained with simultaneous external pulse recording at rest and diring the steady state of exercise at 75 watts. There were no wall-motion abnormalities before and during exercise in both groups. End-diastolic and end-systolic short axis areas of the left ventricle were analyzed at the level of the papillary muscle. Changes in heart rate and peripheral vascular resistence during exercise, compared to resting state, showed no significant difference in both groups. Systolic and diastolic blood pressures, however, increased more markedly in the elderly than in the young group during exercise (p<0.05), while left ventricular ejection time shortend more markedly during exercise in the young than in the elderly group (p<0.01). End-diastolic and end-systolic short axis areas did not show significant difference at rest or significant changes during exercise in both groups. The fractional change in short axis area and mean velocity of the fractional change in short axis area, both considered useful indices of myocardial contractility in the absence of wall-motion abnormalities did not show significant difference at rest in both groups. During exercise, the latter increased significantly in the young group (p<0.05), although its changes from the resting state did not show significant difference in both groups. These results suggest that myocardial contractility in the healthy elderly men is not decreased in comparison to that in the healthy young subjects. Two dimensional echocardiography during dynamic exercise is considered an useful noninvasive method in evaluating the cardiac function in elderly men.
Serum contents of thirty-five free amino acids and other ninhydrin-positive substances, hereinafter referred to as AA, were investigated in consecutive decennial age groups of male and female healthy individuals with normal weights and obese persons, ranging from neonatal (cord blood) to eighties, as a basic study on the amino acid metabolism. The study has revealed remarkably characteristic findings in relation to age, sex and obesity. (1) Cord serum AA showed higher concentrations in males than in females but there was no significant difference between sexes in the cord blood AA/maternal blood AA ratio, ranging between 1.0 and 2.0 in both sexes. Of individual amino acids and ninhydrin-positive substances in the cord serum, phosphoserine, serine, asparagine, glutamic acid, glutamine, citrulline, cystathionine, methionine, isoleucine, ethanolamine, 1-methylhistidine, 3-methylhistidine, anserine and carnosine were found to be at significantly higher levels in males. (2) Male infants and children disclosed a significantly greater value for serum total AA concentration than females. Of the individual AAs, asparagine, proline, citrulline, α-amino-n-butylie acid, cystathionine, tyrosine, ornithine, phenylalanine, ethanolamine, lysine, anserine, carnosine and arginine showed significantly higher values in the male. (3) The serum total AA level increased progressively with advancing age from the teens to the forties, reaching a peak in the forties, both male and female. At all ages the obese exhibited greater values for serum total AA than the normal weight groups. (4) Serum essential and non-essential AA levels varied significantly between sexes as well as with aging. Particularly, serum levels of branched AAs in males reached peaks at the thirties and declined thereafter till the eighties, whereas in females, they fluctuated with peaks at the twenties and showed the lowest values at the fifties. (5) Ketogenic AAs in the serum of males increased to peaks at the forties with subsequent gradual decline. In the female, they increased to peaks at the thirties and then decline to the lowest levels at the fifties, followed by a trend of gradual elevation. The serum ketogenic AA levels were significantly higher in males throughout life except the seventies and eighties. (6) Glycogenic AAs showed the highest concentrations in cord serum and fell markedly during infancy and childhood, followed by a progressive rise to reach peaks at the thirties in both males and females. They declined thereafter.
Morphometric studies have been made on age changes in the epithelial cell mitochondria of the proximal tubules of rat kidneys in relation to their function. Mitochondrial volume per cell was significantly larger in 12 and 18 month old rats than in 2 and 25-29 month old rats. Total volume of mitochondria in the convoluted tubuli of the kidney was estimated to be maximum in the 18 month old rats, and the volume significantly decreased in the 25-29 month old rats; the mitochondrial cristae were arranged most sparsely in the former cases and become to be significantly compact in the latter. From above, each mitochondrion of the renal convoluted tubuli seems to function more actively in the 25-29 month old rats, in which the number of the convoluted epithelial cells is significantly smaller than in the 18 month old ones.
In order to clarify the abnormality of bone metabolism underlying compression fracture of the spine, 30 patients with compression fracture with mean age of 77±1 years were compared with 24 patients without compression fracture with mean age of 75±2 years. Serum calcium, phosphorus, total protein and albumin values were not significantly different between the two groups but serum alkaline phosphatase was significantly higher in the fracture group, 8.1±0.5 (KA) than the non-fracture group, 6.0±0.7 (KA). Bone mineral content (BMC) determined by the Norland- Cameron photon absorptiometry was lower in the fracture group than in the non-fracture group. Ulnar resonance (F) multiplied by bone length (L), FL, expressing velocity of sound propagation over the bone and (FL)2×BMC expressing Young's modulus was also significantly lower in the fracture group than in the non-fracture group. Measurement of these physical properties of bone would provide a useful method of non-invasive evaluation of bone strength and suceptibility to fracture.
When the rats were kept under conditions of reduced oxygen supply, thiobarbituric acid (TBA) reactive substances in the serum, in the abdominal arterial wall and in the brain tissue showed a significant increase at two weeks. While, the liver tissue levels of TBA reactants were slightly increased, but the change was insignificant at two weeks. At four weeks of feeding under conditions of reduced oxigen supply, the serum, brain tissue and liver tissue levels of TBA reactants declined near the values obtained before onset of the experiment. But the TBA reactants in the abdominal arterial wall showed a still higher increase. These observations indicated the possibility that hypoxia might be one of the factors predisposing to the accumulation on lipid peroxide in the arterial wall. We cannot explain the increase in TBA reactive substances in conditions of hypoxia exactly, but the fact that TBA reacting substances increase in conditions of hypoxia suggests that peroxidation may occur not only in conditions of excessive supply of oxygen but also in conditions of short supply of oxygen. This phenomenon may provide an important clue to the elucidation of the causes of various clinical disorders arising from hypoxia.
To evaluate the contractile state of the left ventricle in patients with hypertension by Vcf (velocity of circumferential fiber shortening), we performed echocardiographic measurements of left ventricular dimensions. The subjects (all males, aged 30 to 79) were 92 hypertensives (HT) and 80 normotensives. HT were classified into three groups according to the following echocardiographic and electrocardiographic criteria: Group I, no left ventricular hypertrophy (left ventricular posterior wall thickness at end-diastole (WTd)≤1.2cm) and no ST depression, 45 patients: Group II, left ventricular hypertrophy (WTd≥1.3cm) without ST depression, 30 patients; and group III, left ventricular hypertrophy (WTd≥1.3cm) with ST depression (4-1, 4-2 or 4-3 of Minnesota code), 17 patients. Mean midwall Vcf (Vcf) was calculated from left ventricular dimensions, and mid-systolic stress (stress) was calculated from left ventricular dimensions and systolic blood pressure. Since Vcf showed a significant inverse correlation with stress in normotensives, group I and II, comparison of Vcf adjusted for stress between each hypertensive group and normotensives was performed by a two way analysis of variance. The analytical results were as follows: Vcf showed a significant increase in group I, no significant difference in group II, and a significant decrease in group III, in comparison with normotensives. These results indicate that the contractile state of the left ventricle in patients with hypertension is augmented in group I without hypertrophy, and maintained in group II with hypertrophy, but depressed in group III with hypertrophy and ST depression which suggests myocardial change.
Many hematologic studies have shown that erythrocyte count decreases, while its size increases in the aged. Present study was performed to confirm these observations and evaluate whether vitamin B12 or folate deficiency play any role in the aging-changes of hemopoiesis by using improved deoxyuridine suppression test. Improved deoxyuridine supprossion test applying a multiple automatic cell harvester was used with good sensitivity for diagnosing the deficiency of these substances. 1. 102 healthy male subjects, ranging 20-79 years old, were strictly selected. The RBC and Hb level tended to decrease with age. However when this decline was checked by age decade, significant decline was found only 70 years old. The MCV and MCH were different from the RBC and Hb in that the significant increase was noted in the eight decade. The MCHC remained constant with advancing age. 2. Fresh bone marrow cells obtained from 10 young (20-38 years) and 10 aged (70-82 years) males. The deoxyuridine suppression tests were normal in both young and old age groups. This means that the route of dU to dTMP in thymine-DNA synthetic pathway is intact and there is no evidence of vitamin B12 and/or folate deficiency in the aged. Therefore we conclude that the deficiency of vitamin B12 or folate is not the cause of macrocytic changes of erythrocyte in the aged. Although several modifications of the original Metz's method were developed, these methods were still too complicated for clinical use. We modified the Wickramasinghe's method by applying a multiple automatic cell harvester. Our simplified deoxyuridine suppression test saves three hours in comparison with those previous ones and has made it possible to diagnose megaloblastic anemia within five hours after bone marrow aspiration.