Search PubMed⌕ Search

Biomedical subjects

A H Norris

Publications and source records attributed to A H Norris.

11 recordsLinked to original sources
PubMed1979

Age-related differences in lactate distribution kinetics following maximal exercise.

Lactate concentrations were determined at 3, 5, and 7 min of recovery following maximal, continuous, multi-stage treadmill work in 180 men, aged 20-80 years, who were participants of the Baltimore Longitudinal Study of Aging. Each subject was placed into one of six age groups, e.g., 20-29, 30-39, etc. As expected, average concentrations decreased consistently with age. All three sampling times were similar in characterizing maximal lactates for the youngest men. For each older group, except for the oldest, the later values were significantly (p less than 0.01) higher than the 3-min values. For subjects in their 50's and 60's mean concentrations continued to rise through the 7th min. These data suggest that in man there is a progressive, age-related diminution of ability to diffuse lactate from muscle and/or distribute it into its space. This may result in decreased endurance and work capacity and a prolongation of recovery. As an alternative to multiple sampling and analyses for maximal lactate, single blood samples should be obtained no sooner than 5 min of recovery for men up to age 50, and at 7 min for those between 50 and 70 years. Variability among the men over 70 years of age was large enough to preclude single-sample alternatives.

Adult↗
PubMed1979

Osteoarthritis of the hand: age-specific joint-digit prevalence rates.

The left hand of each of 903 white males, most of them well-educated professionals, was evaluated for osteoarthritis, in the ongoing Baltimore Longitudinal Study of the Gerontology Research Center. The results of the joint-digit prevalence study indicated that: 1) the prevalence of osteoarthritis varies from one digit to the other; 2) osteoarthritis is considerably more prevalent in the distal than the proximal interphalangeal joints, regardless of digit or age group; 3) this disease is not only more prevalent in the distal interphalangeal joints, but it usually appears in a more severe form in the distal than in the proximal interphalangeal or the metacarpophalangeal joints. 4) Assuming that the presence of osteoarthritis in one joint is independent of the presence of the disease in the other joint of the same digit, there is an excess of digits with osteoarthritis in both the distal and proximal interphalangeal joints. This is suggestive of either a common etiology or that the presence of the disease in one joint enhances the development of osteoarthritis in the other joint of the same digit.

Adolescent↗
PubMed1979

Osteoarthritis of the hand: longitudinal studies.

Evaluation of the osteoarthritic grades of the hands of 478 participants of the ongoing Baltimore Longitudinal Study suggests that: 1) Joint degeneration due to osteoarthritis is a relatively slow process. The maximum rate of degeneration is seen in the distal interphalangeal joints where the average increase is about 1 grade per individual in an interval of 12 to 16 years between visits in each age group. The rate of degeneration in the proximal interphalangeal joints is much lower than that of the distal interphalangeal joints. 2) The progress of the degeneration in the distal interphalangeal joints of an individual (longitudinally evaluated) follows closely that which is observed at the population level (cross-sectional joint-digit study). That is, it is directly related to the age and the interval between visits. This is not always seen in the proximal interphalangeal joint data. 3) The rate of change in the osteoarthritic grade of individual hands agrees closely with that of their distal interphalangeal joints. This further supports the conclusions reached in a first report that what has been referred to as osteoarthritic grade of the hand of an individual may actually be the higher grade among the distal interphalangeal joints.

Adult↗
PubMed1977

Aging and ethanol metabolism.

The effect of aging on the distribution and elimination of ethanol was studied in a group of 50 healthy subjects ranging in age from 21 to 81 yr (mean, 53.3). Ethanol was administered in a continuous 1-hr infusion at a mean rate of 375 mg/m2 body surface area/min (equivalent to a mean dose of 0.57 gm/kg body weight). Serial blood samples for the determination of ethanol concentration was obtained at 15- to 30-min intervals for up to 4 hr post infusion. Ethanol elimination and distribution were evaluated with the aid of a two-compartment model. Rates of ethanol elimination were not affected by age. Peak ethanol concentration in blood water at the end of the infusion period was correlated with age (r= 0.55, p less than 0.001). Lean body mass and total volume of distirbution fo the ethanol were negatively correlated with age. The smaller volume of distirbution, in association with the decreased lean body mass, most likely explains the higher peak ethanol concentration found in the blood after administration of an ethanol does on the basis of surface area in the old as compared with the young subjects. This study demonstrates that age-related changes in body composition are important factors in the study of ethanol metabolism and its pharmacologic effects.

Adult↗
PubMed1976

Age differences in vitamin B6 status of 617 men.

The effect of age on vitamin B6 metabolism was studied in 617 community-dwelling subjects, ages 18 to 90. These are, for the most part, clinically healthy, educated men whose intake of nutrients is not limited by economic factors. Plasma pyridoxal phosphate (PLP) was used as the primary criterion of vitamin B6 status. About one-third of the subjects were taking supplementary vitamins on their own initiative. The amount of pyridoxine-HCl varied from 0.1 to 105 mg/day. The average plasma PLP of the men not taking a supplement (N = 414) was 12.3 +/-0.3 ng/ml, with 25% of the values below 7.5 ng/ml and 7% below 5 ng/ml. There was a statistically significant decrease in plasma PLP with age of 0.9 ng/ml per decade. For those taking a supplement, the average plasma PLP was 20.5 +/- 1.0 ng/ml, with only 8% of the values below 7.5 ng/ml and none below 5 ng/ml. Glutamic-oxaloacetic transaminase activity in plasma (PGOT) and erythrocytes (EGOT) was determined on all subjects. The ratio of EGOT with in vitro stimulation by PLP to EGOT actual (alpha-EGOT) was also studied. These studies provide the most extensive normative data on vitamin B6 status available on men in the adult years of life.

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↗
PubMed1975

Antipyrine metabolism in man: influence of age, alcohol, caffeine, and smoking.

Age has been shown to influence drug metabolism but effects of aging could be due to other variables that influence metabolism and differ with age. Plasma half-life and metabolic clearance rate of antipyrine were studied in 307 healthy male subjects, aged 18 to 92. Half-life was 16.5% longer and metabolic clearance rate was 18.5% less in a group of the older than in the younger subjects. Both caffeine and cigarette use were positively correlated with the rate of antipyrine metabolism. Multiple regression analysis showed that the effect of smoking was partially responsible for the age differences in antipyrine metabolism. Smoking explained 12% of the variance in metabolic clearance rate and age explained 3%. Our results suggest that studies attempting to quantify the effects of aging on drug metabolism must also take into account other factors that differ with age.

Adolescent↗