Biomedical subjects

J D Tobin

Publications and source records attributed to J D Tobin.

At least 37 records · Page 2Linked to original sources

PubMed1995

Functional improvement with vitamin D replenishment in a cohort of frail, vitamin D-deficient older people.

OBJECTIVE: To evaluate functional improvement in a population of frail, homebound older persons with low vitamin D status as vitamin D stores improve. DESIGN: Randomized, controlled intervention study. SETTING: Subjects' homes and a nursing facility in Baltimore, Maryland. PARTICIPANTS: The first 32 subjects (community-dwelling, homebound older subjects from the Johns Hopkins Elder Housecall Program and nursing home residents from the Johns Hopkins Geriatrics Center) entered in a longitudinal study of vitamin D replacement. MEASUREMENTS: Baseline 25-hydroxyvitamin D levels were measured and repeated at least 1 month after therapy with either placebo or vitamin D (ergocalciferol). Subjects were also administered the Frail Elderly Functional Assessment (FEFA) questionnaire, an instrument demonstrated to be reliable, valid, and sensitive to small increments of functional change in this population. MAIN RESULTS: All subjects started with 25-hydroxyvitamin D levels less than 15 ng/mL. Those subjects whose levels improved by at least 3 ng/mL (> assay coefficient of variation) also demonstrated improvement in FEFA score. Regression analysis between change in FEFA score compared with change in 25-hydroxyvitamin D was significant (r = .4; P = .02). CONCLUSIONS: In this cohort of homebound older people, improvement in vitamin D status was associated with functional improvement as measured by the FEFA questionnaire.

Aged↗

PubMed1995

The association of body weight, body fatness and body fat distribution with osteoarthritis of the knee: data from the Baltimore Longitudinal Study of Aging.

OBJECTIVE: To examine the association of body weight, body fatness, and body fat distribution with osteoarthritis (OA) of the knee. METHODS: Bilateral standing knee radiographs, taken between 1985 and 1991, of 465 Caucasian men and 275 Caucasian women subjects aged 40 and above in the Baltimore Longitudinal Study of Aging were read by one investigator for grade of OA using Kellgren-Lawrence scales. Measures of obesity, assessed at same visit as the last radiograph during this interval, included body mass index, percent body fat, and body fat distribution. RESULTS: Both men and women with definite knee OA had higher age adjusted mean levels of body mass index, while women only had higher age adjusted mean levels of percent body fat. Both women and men in the highest tertile of body mass index had significantly increased odds of both definite and bilateral knee OA; women in the middle and highest tertile of percent body fat had significantly increased odds of both definite and bilateral knee OA, and men in the highest tertile of waist-hip ratio had significantly increased odds of bilateral knee OA. After adjusting for body mass index, however, the association of percent body fat and waist-hip ratio with knee OA in women and men, respectively, was no longer significant. CONCLUSION: These data further extend observations that body weight is associated with both definite and bilateral knee OA in both sexes, and support a stronger contribution of mechanical as opposed to systemic factors to explain this association.

Adipose Tissue↗

PubMed1994

Serum levels of insulin-like growth factor in subjects with osteoarthritis of the knee. Data from the Baltimore Longitudinal Study of Aging.

OBJECTIVE: To examine the relationship between serum levels of insulin-like growth factor 1 (IGF-1) and osteoarthritis (OA) of the knee. METHODS: Serum IGF-1 levels were compared in 162 male and 101 female subjects age > or = 20 stratified by presence of radiographic changes of OA of the knee. RESULTS: Mean serum IGF-1 levels were significantly lower in subjects with knee OA; however, after adjustment for age-related changes in IGF-1 levels, these differences were no longer significant. CONCLUSION: These data fail to support the hypothesis that serum IGF-1 levels are reduced in subjects with OA of the knee independent of the known age-related changes in these levels.

Adult↗

PubMed1994

The relationship of age and gender to prevalence and pattern of radiographic changes of osteoarthritis of the knee: data from Caucasian participants in the Baltimore Longitudinal Study of Aging.

The aim of this study was to estimate the prevalence and pattern of radiographic changes of osteoarthritis (OA) of the knee by age and gender in Caucasian participants in the Baltimore Longitudinal Study of Aging. Bilateral standing weight-bearing radiographs of the knee in 547 male and 351 female subjects (aged 20 and above) were read for changes of knee OA using Kellgren-Lawrence and individual features scales. Prevalence of definite (Kellgren-Lawrence grade > or = 2 changes) knee OA increased with advancing age in both sexes. Approximately 50 percent in both sexes showed bilateral involvement. Men aged 59 and below were more likely to have unilateral impairment than men aged 60 and above; no such differences were found in females. These data demonstrate that age and gender influence both the prevalence and pattern of radiographic changes of knee OA.

Adult↗

PubMed1994

Appendicular bone mass and osteoarthritis of the hands in women: data from the Baltimore Longitudinal Study of Aging.

OBJECTIVE: The association of appendicular bone mass with hand osteoarthritis (OA) was studied in 238 Caucasian female participants aged 40 and above in the Baltimore Longitudinal Study of Aging. METHODS: Bilateral hand radiographs taken between 1978 and 1991 were read for grade of OA using Kellgren-Lawrence scales. Two measures of appendicular bone mass, percent cortical area of the second metacarpal and bone mineral density of the distal radius measured with single photon absorptiometry, were assessed at the same visit. RESULTS: Bivariate analyses showed that increasing grade of hand OA was associated with increasing age and decreasing bone mass as measured by both techniques. After adjustment for age and body mass index, however, neither of these measures of appendicular bone mass remained significantly associated with grade of hand OA. CONCLUSION: Our data fail to support the hypothesis that increased appendicular bone mass is associated with hand OA in women.

Adult↗

PubMed1993

Treatment of somnambulism with anticipatory awakening.

A 8-year-old boy with a 6-year history of parasomnia (twice-weekly sleepwalking with enuresis) was treated by awakening him for 5 nights before the episodes. The sleepwalking stopped entirely. Anticipatory awakening may be a simple, inexpensive, low-risk therapy for somnambulism.

Child↗

PubMed1993

Obesity and osteoarthritis of the hands in women.

The association of obesity and body fat distribution with hand osteoarthritis was studied in 317 Caucasian female subjects aged 40 years and above in the Baltimore Longitudinal Study of Aging. Bilateral hand radiographs taken between 1978 and 1991 were read by one investigator for grade of osteoarthritis using Kellgren-Lawrence scales. Possible risk factors, assessed at same visit as the first radiograph during this interval, included age and measures of obesity, per cent body fat, and fat distribution. Results of bivariate analyses showed that increasing grade of hand osteoarthritis was associated with increasing age, greater mean levels of waist-hip ratio and per cent body fat; there was no association with body mass index. After adjustment for age, however, none of these independent variables remained significantly associated with grade of hand osteoarthritis. These data fail to support hypotheses that measures of obesity are associated with hand osteoarthritis in women independent of their known age-related changes.

Adipose Tissue↗

PubMed1993

An epidemiological test of the hyperinsulinemia-hypertension hypothesis.

The association between hyperinsulinemia and hypertension was tested in a population of 421 men and 228 women from the Baltimore Longitudinal Study of Aging. Subjects are white, middle-class, generally healthy, community-dwelling volunteers who ranged in age from 17-95 yr. Those with disease or medications known to influence any of the studied variables were excluded from the analysis. Twenty-five percent of the subjects were borderline or hypertensive [systolic blood pressure (BP) > or = 140 or diastolic BP > or = 90 mm Hg]. Standard oral glucose tolerance tests were performed; the logarithms of the fasting insulin level and insulin area were used in the analyses. In addition, body mass index and percent body fat (from age and skinfold thickness equations) and waist hip ratio were computed. In simple correlations, systolic BP and diastolic BP were statistically significantly related to insulin levels (only 1-4% of the variance was explained). Since age, body fat, fat distribution, insulin levels, and BP were highly intercorrelated, insulin and blood pressure correlations were examined after controlling for the confounding variables. Correlations of BP and insulin levels adjusted for age, body fat, and fat distribution were entirely nonsignificant. In this large noninterventive population study, the hyperinsulinemia-hypertension hypothesis is not confirmed.

Adolescent↗

PubMed1993

Reliability of grading scales for individual radiographic features of osteoarthritis of the knee. The Baltimore longitudinal study of aging atlas of knee osteoarthritis.

RATIONALE AND OBJECTIVES: The authors present an atlas of individual radiographic features of osteoarthritis of the knee and evaluate the inter- and intra-reader reliability of trained readers using this atlas. METHODS: Four trained readers graded 30 standing anterior-posterior knee radiographs for eight selected features of osteoarthritis (medial and lateral osteophytes, joint space narrowing, and sclerosis; osteophytes of the tibial spines and chondrocalcinosis) as well as the Kellgren-Lawrence global scale. Inter- and intra-reader reliability were calculated using intraclass correlation coefficients. RESULTS: For all features except sclerosis and osteophytes of the tibial spines, inter-reader reliability ranged from 0.63 to 0.83, whereas intra-reader reliability ranged from 0.82 to 0.95. CONCLUSION: Using this atlas, trained readers are reliable in measuring the presence and severity of individual radiographic features of osteoarthritis of the knee. This atlas should be useful in clinical and epidemiologic studies of osteoarthritis of the knee.

Adult↗

PubMed1992

Biochemical parameters associated with low bone density in healthy men and women.

A causal role in age-related bone loss has been attributed to alterations in vitamin D status, the bone mineral regulating hormones, and/or renal function. We assessed biochemical parameters of bone metabolism and renal function in healthy subsets of young and old men (n = 191) and women (n = 120) and evaluated the relationships between these parameters and bone mineral density (BMD) in the radius, spine, and femur. There were no significant associations between BMD at any site and serum 25-OHD, 1,25-(OH)2D, PTH, or creatinine clearance in either young men or in young or old women, after controlling for age. In old men, however, lower radius BMD was significantly related to higher PTH and higher 1,25-(OH)2D and marginally related to lower 25-OHD values. In young men, there were unexpected but significant associations between lower femoral neck BMD and higher serum osteocalcin and urinary calcium/creatinine excretion after age adjustment. In old women, lower spine and radius BMD was also significantly correlated with higher serum osteocalcin. In this healthy, vitamin D-replete population, there were significant cross-sectional declines in BMD in the femur in young and old men and at all sites in old women. Elevated remodeling may be an important feature that contributes to reduced femoral BMD in young men and reduced spine and radius BMD in old women. However, compromised renal function or levels of 1,25-(OH)2D or elevated PTH appear to be neither necessary nor relevant as determinants of osteopenia in the spine or femur in these normal, healthy men and women.

Adult↗

PubMed1992

Sex differences in geometry of the femoral neck with aging: a structural analysis of bone mineral data.

The greater hip fracture rate among elderly women is generally ascribed to differences in femoral neck strength between the sexes. Strength of a given bone is a function of both its material properties and the magnitudes of mechanical stresses within it. This study examined the hypothesis that these apparent strength differences between the sexes are due to dissimilarities in the restructuring of the femoral neck with age, which result in higher stresses in elderly women. Using Hip Strength Analysis, a computer program developed by the authors, femoral neck cross-sectional geometric properties for stress analyses were derived from bone mineral image data of 409 community living, white subjects ranging from 19 to 93 years of age. Though both sexes show declines in femoral neck bone mineral density (BMD) and cross-sectional area with age, only females show a decline in the cross-sectional moment of inertia (CSMI, a geometric index of bone rigidity). The lack of decline in male CSMI appears to be a result of a small but significant increase in femoral neck girth. Similar age-related changes have been observed in the femoral shaft by others. The net effect of these observed changes is that mechanical stresses in the femoral neck of females appear to increase at three times the rate per decade of those of males. These results lend support to the hypothesis that the higher fracture rate in elderly women is due, at least in part, to elevated levels of mechanical stress, resulting from a combination of greater bone loss and less compensatory geometric restructuring with age.

Adult↗

PubMed1992

Glucose tolerance in women: the effects of age, body composition, and sex hormones.

OBJECTIVE: To determine the separate and interactive effects of age, phase of the menstrual cycle, menopausal hormone status, body fat mass, and regional fat distribution on glucose tolerance in healthy women. DESIGN: Retrospective study. SETTING: The Baltimore Longitudinal Study of Aging. PATIENTS: Two hundred sixty healthy women aged 22-89 years. MEASUREMENTS: Plasma levels of estradiol and progesterone, body mass index (BMI), waist-to-hip ratio (WHR), and plasma glucose values in the fasting state (FPG) as well as 120 minutes after 40 gm/m2 of oral glucose (G120) were measured for each participant. RESULTS: We found a progressive decline in oral glucose tolerance of 0.4 mM (6.7 mg/dL)/decade at G120) in women from early to late adult years, with no relationship to phase of the menstrual cycle and no abrupt change associated with the menopause. Multiple regression analysis revealed significant, independent effects of BMI and WHR on FPG and G120. The influence of age (P less than 0.01) on G120 was stronger than that of the BMI or WHR (P less than 0.05). There was no significant relationship between the levels of endogenous sex hormones and glucose tolerance after adjustments for age, BMI, and WHR. However, women taking oral contraceptives, but not those receiving postmenopausal replacement therapy, did exhibit mildly elevated G120 values. CONCLUSIONS: Age per se, and to a lesser extent BMI and WHR, but not levels of endogenous sex steroids, contribute to the physiological decline in glucose tolerance in older women.

Activities of Daily Living↗

PubMed1992

Factor structure of morphometric variables measured on six metacarpal bones.

Morphometry of the second, third and fourth metacarpal bone was performed on hand-wrist radiograms of both hands in a sample of 434 male and 549 female adult subjects. Morphometric data (bone length-L, total diaphysis width-T and medullary canal width-M) and age were processed using principal factor analysis with oblique rotation, separately for males and females. In both sexes three factors accounting for 74.7% of the total variance were extracted, but their patterns of variation differed. Factors-"cumulative environmental-genetic factor", "longitudinal factor", and "transversal factor"-are discussed within the context of their biological meaning affecting the phenotypic formation of metacarpal skeleton in a given population.

Adult↗

PubMed1992

Alcohol consumption in the guinea pig is associated with reduced megakaryocyte deformability and platelet size.

Mild thrombocytopenia is common in alcoholic individuals. Ethanol appears to impair platelet production primarily by affecting the maturing megakaryocyte compartment. We recently showed that guinea pigs have an unusually large number of elongated platelet forms even under conditions of steady-state thrombopoiesis, and a portion of their mature (stage IV) megakaryocytes yield extremely long extensions on micropipette aspiration. This study evaluates the effect of a moderately low level of ethanol consumption by guinea pigs on platelet size and form and megakaryocyte deformability. Adult Duncan Hartley guinea pigs took ethanol 2.5% (vol/vol) ad libitum for 4 weeks under environmentally controlled conditions, never reaching detectable blood ethanol levels (< 0.01%); the platelet count fell 16%. Elongated platelet forms constituted 29% of the cardiac puncture platelets of control animals, but only 3% of the cardiac puncture platelets of animals given ethanol; discocytic platelets of ethanol-treated animals were also significantly smaller. Individual stage III and IV megakaryocytes were aspirated into 5 microns diameter micropipettes by stepwise increment in pressure from 10 to 200 cm water. The extensions drawn from megakaryocytes of ethanol-exposed animals were significantly shorter than the extensions from control megakaryocytes. Extremely long extensions over 50 microns in length were drawn from 21% of the control megakaryocytes but less than 1% of ethanol-exposed megakaryocytes. Moderately low level ethanol consumption was associated with reduced platelet count and size, along with rigidity of mature megakaryocytes in guinea pigs. Few ethanol-exposed megakaryocytes yielded extremely long cell extensions, nor were elongated platelet forms prevalent in the circulation of animals given ethanol.(ABSTRACT TRUNCATED AT 250 WORDS)

Alcoholism↗

PubMed1991

Factors associated with osteoarthritis of the hand in males: data from the Baltimore Longitudinal Study of Aging.

The association of metabolic and physiologic factors with hand osteoarthritis was studied in 888 Caucasian male subjects aged 17-102 years in the Baltimore Longitudinal Study of Aging. Left-hand radiographs taken between 1958 and 1975 were read by one investigator for grade of osteoarthritis using Kellgren-Lawrence scales. Possible risk factors, assessed at the same visit as the last radiograph during this interval, included age and measures of bone mass, body composition, muscle mass, and muscle strength. Results of bivariate analyses of these cross-sectional data showed that increasing grade of hand osteoarthritis was associated with increasing age; greater mean levels of waist/hip ratio and percentage of body fat; and lower mean levels of percentage of cortical area, grip strength, and forearm circumference. After adjustment for age using residuals from best-fit quadratic regression models, none of these independent variables remained significantly associated with grade of hand osteoarthritis. These data fail to support hypotheses that metabolic and physiologic factors are associated with hand osteoarthritis independent of their known age-related changes.

Adolescent↗

PubMed1991

Reversible effects of ethanol in utero on cardiac sarcoplasmic reticulum of guinea pig offspring.

STUDY OBJECTIVE: The aim was to investigate the effects of chronic ethanol exposure in utero on the sarcoplasmic reticulum of the developing heart. DESIGN: Pregnant guinea pigs were given 2.5% ethanol in their drinking water and guinea pig lab chow from day 30 to the end of pregnancy. Control pregnant guinea pigs received regular drinking water and lab chow. Ethanol was discontinued at delivery. Cardiac calcium transport function was evaluated in isolated sarcoplasmic reticulum from offspring of ethanol treated and control guinea pigs killed at 1-3 d and 3-5 months of age. EXPERIMENTAL SUBJECTS: The study group consisted of 28 Camm-Hartley guinea pigs. There were 24 controls of the same species. MEASUREMENTS AND MAIN RESULTS: Maternal deaths, litter size, number of stillborns, newborn body weight, and heart weight were not different in ethanol treated and control guinea pigs and their offspring. Ca2+ uptake, Ca2+ binding, and Ca2+ stimulated ATPase activity in isolated sarcoplasmic reticulum were all reduced in 1-3 d old offspring from ethanol treated mothers when compared to age matched control offspring (p less than 0.05). By 3-5 months, calcium transport in cardiac sarcoplasmic reticulum of ethanol treated offspring was similar to that of age matched control offspring. CONCLUSIONS: Moderate ethanol exposure in utero produced functional cardiac alterations in the newborn which were slowly reversible with abstinence from ethanol.

Adenosine Triphosphatases↗

PubMed1991

Is the recommended daily allowance for vitamin D too low for the homebound elderly?

A population of sunlight-deprived elderly was studied to determine the daily intake of vitamin D and whether dietary intake was sufficient to maintain a normal vitamin D status. Twenty-two subjects over 65 years old with serum creatinine less than 180 mumols/L and confined indoors for more than 6 months were chosen from the community and a nursing home in Southeast Baltimore. Three-day food records were obtained along with serum levels of 25-hydroxyvitamin D (25-OHD), 1,25-dihydroxyvitamin D (1,25-(OH)2 D), and intact parathyroid hormone (PTH). The mean daily vitamin D intake was over twofold greater than the adult Recommended Daily Allowance (RDA) of 200 IU. The mean 25-OHD level was 40 nmol/L (normal 25-138 nmol/L) with seven patients less than 25 nmol/L. Of these participants with 25-OHD values less than 25 nmol/L, the mean vitamin D intake was 467 IU (range 36-1096 IU). We conclude that the current RDA seems inadequate for many older individuals who do not get sun exposure. This particular population of elderly is at risk to develop vitamin D deficiency and the associated complications.

Aged↗

PubMed1990

The longitudinal course of hand osteoarthritis in a male population.

In this prospective analysis of the natural history of osteoarthritis (OA) of the hand, the incidence and progression of various radiographic features of OA were examined in 177 men who participated in the Baltimore Longitudinal Study of Aging. Subjects who were less than 60 years old were selected based on the availability of at least 4 hand radiographs taken during at least 20 years of followup, while subjects who were age 60 or older were required to have had at least 4 hand radiographs taken during only 14 years of followup. Individual joints of the hands were graded for the presence and severity of 5 features of OA: osteophytes, joint space narrowing, subchondral sclerosis, lateral deformity, and cortical collapse. They were also graded according to the global Kellgren/Lawrence scale. The incidence and rate of progression of OA, as measured by all scales, increased in progressively older age groups. Cox's proportional hazards models showed that isolated doubtful osteophytes (Kellgren/Lawrence grade 1) and isolated joint space narrowing predicted the development of the radiographic features of OA. The rate of OA progression slowed as the severity increased. We conclude that, in men, the incidence of radiographic features of hand OA increases with age. Regardless of age, the earliest radiographic signs of OA are joint space narrowing and doubtful osteophytes.

Aging↗