PubMed Health⌕ Search

Biomedical subjects

G A Borkan

Publications and source records attributed to G A Borkan.

16 recordsLinked to original sources
PubMed1986

Poor growth prior to early childhood: decreased health and life-span in the adult.

Previous studies in animal populations have shown that stunted neural and thymolymphatic growth early in development may result in permanently impaired neural and immune function, decreased body growth, vertebral wedging, and decreased life-span. In the human adult, small vertebral neural canal (VNC) diameters may reflect early stunted neural and immune development and impaired function that leads to decreased health (inferred by greater vertebral wedging) and life-span in the adult. VNC, which complete their growth by early childhood (age 4), are markers of early development in adults. On the other hand, features following general body growth, such as height, weight (represented here by vertebral body height) continues to grow until young adulthood. They are less reliable, because they readily experience catch-up growth (even in chronically stressed populations) and, unlike VNC, may mask poor early growth. To test associations between early growth and adult health and life-span in humans, we measured 2,060 VNC, vertebral heights, vertebral wedging, nerve-root tunnel lengths, severity of vertebral osteophytosis, and ages at death in 90 adult (aged 15-55 years) prehistoric skeletons (950-1300 A.D.). Tibial lengths were also measured in a subsample (n = 30). Multivariate, bivariate, and nonparametric analyses showed that small VNC are significantly associated with greater vertebral wedging and decreased life-span (P less than 0.05-0.00001). VNC are independent of vertebral body heights and tibial lengths (general body growth). VNC, but not statural components, are useful in predicting adult health, presumably because they reflect neural and immune development and do not readily experience catch-up growth. Thus, longitudinal retrospective measures of early growth and adult health were systematically linked within individuals regardless of confounding factors operating over the 350-year time period. Since this research was completed, this model has repeatedly been independently confirmed in four living urban industrial populations. Longitudinal retrospective analysis was employed together with direct measures of VNC, neural and immune function. Together these results suggested that it may be essential to improve growth prior to early childhood in order to maximize adult health and life-span.

Adolescent↗
PubMed1986

Body weight and coronary disease risk: patterns of risk factor change associated with long-term weight change. The Normative Aging Study.

Previous studies have suggested that excess body weight increases coronary disease risk by modification of the levels of other risk factors and in addition may contribute to overall risk independently. Few studies, however, have systematically characterized long-term change in risk factors with specific changes in overall weight while they have controlled for the effects of multiple potential confounders. Also, very little information is available on the differential impact of weight change on risk factor changes with advancing age. The present investigation used 15 years of longitudinal data collected on 1,396 men participating in the Veterans Administration Normative Aging Study in Boston, Massachusetts. Multiple regression analysis was used to predict change in each of eight putative coronary disease risk factors from change in weight and the interaction between weight change and age. These included blood pressure, serum cholesterol, triglycerides, fasting and two-hour postprandial blood glucose, uric acid, and forced vital capacity of the lungs. After controlling for initial levels of the risk factor, weight, age, and smoking status, change in weight remained a significant predictor of long-term change in each of the risk factors studied. In addition, the interaction between weight change and age was significant for fasting glucose, uric acid, and forced vital capacity, indicating that the effect of weight gain on uric acid and forced vital capacity was greater in younger men whereas the effect of weight gain on fasting glucose was greater in older men.

Adult↗
PubMed1986

Relationship of fat distribution to glucose tolerance. Results of computed tomography in male participants of the Normative Aging Study.

Computed tomography (CT) scanning was used to assess the relationship of glucose tolerance to fat distribution in men. Three cross sections [chest (including upper arms), abdomen, and thigh] were scanned in 41 men randomly selected from the Normative Aging Study, a longitudinal study of aging. Greater amounts of fat in the upper body and greater ratios of upper-body fat to lower-body fat were significantly correlated with higher 2-h serum glucose levels after adjustment for age and body mass index. In particular, intra-abdominal fat, a feature uniquely measured by CT, was a significant correlate of 2-h glucose. Largely parallel results were obtained when we compared a sample of male diabetic subjects (N = 8) with the male normal subjects from our random sample. This investigation demonstrates that body fat distribution, adjusted for overall degree of obesity, is a significant correlate of glucose tolerance even in a sample unselected for extremes of physique.

Abdomen↗
PubMed1985

Comparison of body composition in middle-aged and elderly males using computed tomography.

Computed tomography (CT) scans were taken of 21 middle-aged men (mean age 46.3 years) and 20 older men (mean age 69.4 years) to measure differences in body composition with age. Overall, the older men weighed 8.2 kg less than the middle-aged men, and this difference was primarily the result of their having less lean tissue. Although fat mass (by whole body potassium counting) was only slightly less in older men, there were distributional differences in fat between the age groups. Total abdomen adipose tissue area (from CT) was similar in both groups, although the subcutaneous portion of the abdomen adipose tissue was less in the older men, and they had correspondingly more adipose tissue within the abdominal cavity. Muscle areas of the leg and arm were significantly less in the older men, as were all lean tissues of the abdomen and chest. When these data were corrected for differences in body weight with age, the results were still significant, suggesting a centripetalization and internalization of fat with age. Causes of this apparent fat redistribution and decrease of lean tissue with age were not revealed by this study and are presently unknown.

Adipose Tissue↗
PubMed1983

Age changes in body composition revealed by computed tomography.

Computed tomography scans were taken of 21 middle-aged men (M age 46.3 years) and 20 older men (M age 69.4 years) to measure differences in body composition with age. Overall, the older men weighed 8.2 kg less than the middle-aged men, and this difference was primarily the result of their having less lean tissue. Although fat mass was only slightly less in older men, there were clear distributional differences in fat between the age groups. Total abdomen fat area was similar in both groups, although the subcutaneous portion of the abdomen fat was less in the older men, and they had correspondingly greater intra-abdominal fat. Muscle areas of the leg and arm were significantly less in the older men, as were all lean tissues of the abdomen and chest. Analysis of fat accumulation between muscles of the abdomen and leg indicated fat infiltration into lean tissue in the older men. Causes of this apparent fat redistribution and lean body mass decline with age are presently unknown.

Adipose Tissue↗
PubMed1982

Comparison of ultrasound and skinfold measurements in assessment of subcutaneous and total fatness.

Ultrasound (A-scan mode) and skinfold methods were evaluated in the measurement of subcutaneous fat thickness and prediction of total fat weight (by whole body potassium counting). Based on intraobserver correlations on 39 men at 15 body sites, skinfold caliper measurements were more reproducible than ones obtained by ultrasound. Measurements made with the two techniques at the same site typically produced different mean estimates of fat thickness. However, scores were often highly correlated with each other, indicating similar relative rankings of subjects by each technique. Skinfolds were more highly correlated with total fat weight than were ultrasound measurements, but body weight. Anthropometric measurements were highly correlated with fatness because of their association with body weight, and when this relationship was statistically controlled for, they typically lost their predictive effectiveness. Multiple regression analyses revealed that the best predictors of fat weight were body weight along with skinfold and ultrasound measurements. These results suggest that skinfolds are a more effective means of assessing subcutaneous fat than ultrasound, especially when the large difference in cost of equipment is considered.

Abdomen↗
PubMed1982

Comparison of visually estimated age with physiologically predicted age as indicators of rates of aging.

The commonly held view that people age at different rates derives largely from visual estimates of age. Although most people "look their age' everyone can cite examples of individuals in middle and late adulthood who appear to be aging very slowly or very rapidly. Efforts to quantify aging rates scientifically require measurement of a large number of physiological parameters in a large population sample. This paper compares visual estimates of age with physiologically predicted measures to determine their value as indicators of the rate of aging. This study used data from 1086 male participants in the Baltimore Longitudinal Study of the Gerontology Research Center, NIA. These men have provided comprehensive biomedical and psychosocial data at one and one-half years intervals for as long as 20 years. The visual estimate of age was made by the examining physician at the first study visit of each participant, without knowledge of the man's actual age. The error of this estimate was determined by subtracting actual age from estimated age. Correlation analysis of error in estimated age with an objective assessment of biological age based on physiological variables indicated a significant association between the two approaches. When men who have died since their study participation were compared with survivors, the former were found to have been significantly 'older for their age' than the latter using both visual and physiological estimate approaches. To determine whether certain lifestyle traits were associated with variation in these two indicators, multiple regression analyses were performed. These showed that men who smoked, who were fatter, or who were in poor health were predicted as older than their chronological age peers using both approaches. Results of this study suggest that the easily determined visual estimate of age may be a useful indicator of aging rate within a population.

Adolescent↗
PubMed1982

Assessment of abdominal fat content by computed tomography.

Computed tomography (CT) produces thin cross-sectional radiographs that may prove very useful in body composition research. CT images of the abdomen allow computerized measurement of total fat area, and also enable the differentiation of subcutaneous fat from intraabdominal fat. The preset investigation examines whether a single CT scan of the abdomen provides an accurate indication of overall abdominal adiposity. Graphs of measurements from seven sequential scans of the abdomen in eight patients showed that rankings of total abdominal area, total fat area, subcutaneous and intraabdominal fat area are relatively consistent no matter which abdominal level is chosen. Correlations of 0.89 to 0.99 between single scans and the average values for all scans show that a single CT image contains the same information on adiposity as a series of scans. These results suggest that future CT studies of body composition can limit radiation exposure by using single scans at different anatomical sites. If only a single scan at one site can be obtained, the level of the umbilicus may be the most useful, because it contains the largest percentage of fat in the body, and best allows differentiation of intraabdominal from subcutaneous fat.

Abdomen↗
PubMed1980

Assessment of biological age using a profile of physical parameters.

The present study describes a new approach to the assessment of biological age in adults using a profile of physical parameters. The investigation was based on data from 1086 adult male participants in the aging study of the Gerontology Research Ctr., Baltimore, MD. For each of 24 age-related variables, data were transformed into biological age scores reflecting a man's status relative to his chronological age peers. Analysis of the mean biological age profiles of men who were estimated by physicians as looking older than their age showed them to be biologically older on the profile parameters as well. Comparison of age-corrected scores of 166 men who have died with those of survivors reveals the deceased group to have been biologically older than the survivors at the time they were measured. These results suggest the value of this technique in investigating interindividual variation in the aging process.

Adolescent↗
PubMedDate not supplied

Relationship between cigarette smoking, chest size and body size in health-screened adult males.

Previous investigations have shown that chest dimensions and pulmonary function are positively correlated in healthy individuals. It is not known, however, whether the pulmonary effects of cigarette smoking may modify chest size during adulthood. The present study used cross-sectional data from 1557 healthy male participants in the Normative Aging Study of the Veterans Administration Outpatient Clinic, Boston. Because elastic recoil of the lung is decreased in cigarette smokers, we hypothesized that chest circumference would increase while chest expandability would decrease in these individuals. Preliminary analyses showed that smokers differed from non-smokers and former smokers in age, weight and fatness. For this reason, associations of chest dimensions with smoking status were evaluated after statistical correction for age and body size. With men of all ages grouped, chest expansion of smokers was significantly lower than non-smokers, but their chest size and shape were similar. When covariance analyses were performed separately for men under 50 and over 50 years, older smokers were characterized by slightly larger chests than non-smokers or former smokers, though there was no difference among younger men. Results of this study indicate that external chest dimensions of cigarette smokers reflect the pulmonary changes they experience, and demonstrate that a portion of the increased variability in chest measurements seen in older individuals is attributable to cigarette smoking.

Adult↗
PubMedDate not supplied

Relationships between computed tomography tissue areas, thicknesses and total body composition.

Computed tomography (CT) scanning was evaluated for its potential application to body-composition research. Three cross-sections (upper leg, abdomen, chest including upper arms) were scanned in 41 healthy men (mean age 57.6 years). Subcutaneous fat thicknesses measured at specific sites on the CT scans were correlated with the total area of fat from the same scans. For the chest and leg cross-sections, correlations were highly significant. Subcutaneous fat thicknesses at the abdomen were relatively poorer correlates of total abdomen fat area, because they were unrelated to intra-abdominal fat. Correlation analyses were performed between fat areas of each cross-section and total fat weight (by 40K counting), and the abdomen yielded the highest correlations. Multiple regression was used to predict abdomen fat area from external anthropometry, and abdomen circumference plus one skinfold provided excellent prediction of total abdomen fat area (R2 = 0.79). Subcutaneous or intra-abdominal fat areas separately were not predicted as well by external measurements. When lean body weight was predicted by multiple regression, leg lean area was the best predictor of any anatomical cross-section.

Adipose Tissue↗