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Biomedical subjects

J F Aloia

Publications and source records attributed to J F Aloia.

At least 19 recordsLinked to original sources
PubMed1995

Skeletal alterations in hypophysectomized rats: I. A histomorphometric study on tibial cancellous bone.

BACKGROUND: Hypophysectomy (HX) results in a cessation of bone growth and a decrease in bone metabolism. The purpose of this study is to examine the effect of HX on the static and dynamic histomorphometry of cancellous bone in the secondary spongiosa of the proximal tibial metaphysis in rats. METHODS: Female rats, at 2 or 3 months of age, were HX and sacrificed at 0, 5 days, 2 and 5 weeks after the surgery. Age-matched intact rats served as controls. Cancellous bone histomorphometry was performed on double-fluorescent labeled, 30-microns-thick sections of the proximal tibia. Tartrate-resistant acid phosphatase histomorphometry was performed at 5 days on HX and control rats to evaluate the resorption in the metaphyseal bone. RESULTS: Although the intact rats gained in body weight, tibial length, tibial weight, and density after 5 weeks, these changes did not occur following HX. As compared to the basal group, HX resulted in a decrease in the density and dry weight of the metaphysis. The histomorphometric data showed that the cancellous bone volume and trabecular number of the secondary spongiosa were decreased and the separation was increased in the HX rats. The dynamic results showed that HX significantly decreased longitudinal growth rate and tissue-based bone formation and resorption. However, the bone surface-based eroded surface, labeled surface, the mineral apposition rate, and the bone formation rate did not differ between the intact and the HX rats at either the 2 or 5 weeks study. Five days after HX, the bone surface and tissue-based osteoclast surfaces were significantly lower in the HX than in the intact rats. CONCLUSIONS: Pituitary hormone deficiency results in cancellous bone loss. The bone loss is due primarily to the suppression of longitudinal growth-dependent bone gain and the inhibition of tissue-based bone turnover with a lower bone formation relative to bone resorption. The surface-based bone turnover is not affected.

Animals↗
PubMed1995

Skeletal alterations in hypophysectomized rats: II. A histomorphometric study on tibial cortical bone.

BACKGROUND: Pituitary hormones play an important role in bone growth, modeling, and remodeling. The purpose of this study is to examine the effect of hypophysectomy (HX) on tibial cortical bone with histomorphometry. METHODS: Forty-five female Sprague-Dawley rats, at 3 months of age, were hypophysectomized or served as intact controls. They were sacrificed at 0, 2, and 5 weeks after the surgery. Cortical bone histomorphometry was performed on double-fluorescent-labeled 30-mcm-thick sections of the tibial shaft. RESULTS: The dry weight and density of tibial diaphysis and the cortical bone area of the tibial shaft in the HX rats were significantly lower (P < 0.05) than that of the age-matched intact rats, but did not differ between the HX and basal control rats. The dynamic data show that the bone formation parameters (labeled surface, mineral apposition rate, and bone formation rate) were profoundly decreased (P < 0.01) on both the periosteal and endocortical surfaces in the HX rats as compared with the age-matched intact rats at the 2 and 5 weeks. However, the decrease in the labeled surface was much less on the endocortical envelope than on the periosteal envelope in the HX rats. Although no significant change was detected in the medullar size between the HX and age-matched intact rats, the eroded surface on the endocortical surface was greater (P < 0.05) in the HX rats than in the intact rats at either time point. CONCLUSIONS: Hypophysectomy-suppressed, radial growth-dependent bone gain without a bone loss in the tibial shaft of the young rat. This is associated with decreased modeling-dependent bone formation. A greater eroded surface on the endosteum did not affect the marrow size at 5 weeks after hypophysectomy.

Aging↗
PubMed1995

Effect of ovariectomy on cancellous bone in the hypophysectomized rat.

This experiment studied the effects of hypophysectomy (HX) and ovariectomy (OV) on cancellous bone in the proximal tibia and distal 5th lumbar vertebra by dynamic histomorphometry. Forty-eight female Sprague-Dawley rats, 3 months of age, were divided into age-matched control, HX, OV, and HX + OV (HO) groups. Ten rats were sacrificed at 3 months of age as baseline controls, and the rest of the animals were sacrificed 5 weeks after the surgery. While the age-matched controls, and the OV rats significantly increased in body weight compared with the baseline control rats, cancellous bone volumes in the proximal tibia and distal 5th lumbar vertebra increased in the age-matched controls and decreased in the OV rats. In the HX and HO rats, body weight equaled baseline control values, and their cancellous bone volumes were decreased with a poorer trabecular architecture in both bone sites. In all HX, OV, and HO rats, uterine weight and serum estradiol were significantly decreased. OV significantly increased longitudinal bone growth and the tissue- and surface-based bone formation and bone resorption parameters in both the proximal tibia and 5th lumbar vertebra (p < 0.05). HX alone or HO significantly decreased longitudinal bone growth and the tissue-based bone formation rate without significantly affecting surface-based bone formation and bone resorption parameters when compared with the age-matched controls. No significant differences were detected in any variables between the HX alone and HO rats.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1995

The influence of menopause and hormonal replacement therapy on body cell mass and body fat mass.

OBJECTIVE: Our purpose was to determine the efficacy of dietary calcium augmentation in the prevention of early postmenopausal bone density loss in comparison with hormonal replacement therapy and placebo. STUDY DESIGN: A three-arm parallel randomized trial comparing the influence of placebo, dietary calcium augmentation, and estrogen-progesterone-calcium in 118 women who were within 6 years of menopause was conducted. Dual photon absorptiometry was performed annually to measure lean and fat mass. In addition, the ratio of fat in the trunk/extremities was measured. RESULTS: Body weight increased in each group. The increase was statistically significant in the hormone replacement group (0.8 kg/year). The percent of body fat increased in each group from baseline measurements, with the greatest increase in the hormonal replacement group. There was a decline in the extremity/trunk ratio in the hormonal replacement group as a result of a relatively greater increase in the trunk fat mass. There was a rapid rate of loss in lean body mass that was equal among groups. CONCLUSIONS: Menopause is associated with a gain in fat mass and a loss of lean body mass, but these changes in body composition are not prevented by hormone replacement therapy.

Adipose Tissue↗
PubMed1995

To what extent is bone mass determined by fat-free or fat mass?

One hundred sixty-four healthy black and white women aged 24-79 y were studied to determine to what extent bone mass is determined by fat-free mass (FFM). A multicomponent approach to body composition, with techniques that are not interdependent, was used. The measurements included dual x-ray absorptiometry (DXA), prompt gamma-neutron-activation analysis, inelastic neuron scattering, tritiated water dilution, and whole-body counting. Univariate correlations showed significant relationships of all the fat-free measures and most of the fat measures with bone mass measured by total body calcium (TBCa). Data from pre- and postmenopausal women were analyzed separately. The average FFM by itself explained 50-55% of the variability in TBCa whereas the average fat mass by itself explained only 5-18% of the variability. The contribution of fat mass was consistently greater in postmenopausal than in premenopausal women. When stepwise multiple regression with TBCa was performed to determine the influence of adding fat mass, height, and race to the relationship of FFM with TBCa, the variation explained by average FFM was 56% premenopausal, 50% postmenopausal; by height 3% premenopausal, 6% postmenopausal; by race 4% premenopausal, 8% postmenopausal; and average fat mass was not significant. Average values for fat mass and FFM were obtained by averaging all the methods used. In conclusion, in black and white healthy women, although bone mass may be partially influenced by fatness or race, the major determinant of bone mass is FFM. Fat mass may play a more important role in postmenopausal women.

Absorptiometry, Photon↗
PubMed1995

Comparative study of body composition by dual-energy x-ray absorptiometry.

UNLABELLED: Dual-energy x-ray absorptiometry (DEXA) is a readily available technique that has recently been applied to measurement of body composition. In order to validate this technique, results from DEXA were compared with fat-free mass (FFM) and fat mass (FM) measured by total body levels of potassium (TBK), nitrogen (TBN), water (TBW) and carbon (TBC). METHODS: A healthy population of 127 white women and 38 black women with a body mass index of 18-30 were recruited. RESULTS: Compared with each of the other methods, DEXA overestimated FM and underestimated FFM. The slopes of the FM by DEXA versus the FM from each of the four methods were approximately the same, with a s.e.e. ranging from 2.4 to 3.0 units. The slopes of DEXA in comparison to FFM, however, ranged from 0.61 to 0.74 and were significantly less than unity, with a s.e.e. of 1.6 to 2.4 units. CONCLUSION: These findings suggest that at high values of FFM, DEXA is measuring something different from the FFM measured by TBW, TBN and TBK. The program for separating bone and soft tissue and for separating soft tissue into fat and lean at higher values in the DEXA method may need to be adjusted.

Absorptiometry, Photon↗
PubMed1994

Calcium supplementation with and without hormone replacement therapy to prevent postmenopausal bone loss.

OBJECTIVE: To determine whether augmentation of dietary calcium is effective in the prevention of early postmenopausal bone loss. DESIGN: Three-arm, placebo-controlled, randomized parallel trial. The study duration was 2.9 +/- 1.1 (SD) years. SETTING: General community. PARTICIPANTS: 118 healthy, white women 3 to 6 years after spontaneous menopause, recruited by community announcement. INTERVENTIONS: Random allocation to daily intake of 1700 mg of calcium (calcium carbonate given in divided doses with meals); placebo; or conjugated equine estrogens (0.625 mg; days 1 to 25), progesterone (10 mg; days 16 to 25), and 1700 mg of elemental calcium daily. Each participant received 400 IU of vitamin D daily. MAIN OUTCOME MEASURES: Total body calcium measured by delayed gamma neutron activation analysis and whole-body counting; bone mineral density of the spine, femur, and radius measured by photon absorptiometry. RESULTS: Bone mineral density declined in the placebo group for the lumbar spine (-2.1%/y; 95% Cl, -3.3 to -0.9), femoral neck (-2.0%/y; Cl, -2.6 to -1.2), trochanter (-1.6%/y; Cl, -2.4 to -0.8), Ward triangle (-2.7%/y; Cl, -3.7 to -1.7), and total body calcium (-2.0%/y; Cl, -2.2 to -1.8). Rates of change were intermediate for calcium augmentation compared with placebo and estrogen-progesterone-calcium but statistically significant compared with placebo for total body calcium (-0.5%/y; Cl, -0.9 to -0.1; P = 0.006) and the femoral neck (-0.8%/y; Cl, -1.4 to -0.2; P = 0.03). CONCLUSIONS: Although less effective than estrogen-progesterone-calcium, calcium augmentation alone significantly retards bone loss from the femoral neck and improves calcium balance in recently postmenopausal women. Dietary calcium augmentation should be recommended as a strategic option in helping to prevent early postmenopausal bone loss.

Analysis of Variance↗
PubMed1994

Growth hormone administration potentiates the effect of treadmill exercise on long bone formation but not on the vertebrae in middle-aged rats.

To determine whether growth hormone administration would potentiate bone response to the stimulation of exercise, 80 female rats aged 14 months were divided into control (CON), ovine growth hormone administration (0.5 mg/kg daily) (GH), treadmill exercise (17 m/minute, 60 minutes daily) (EX), and GH+EX groups for 9 and 16 weeks. Static and dynamic histomorphometry were measured on the tibial shaft and (L-5) vertebral cortical bone. The periosteal and endocortical bone formation rate of the tibial shaft were higher in both EX and GH+EX than in the CON group in the 9-week study. There is a synergistic interaction between the two interventions in both cortical surfaces. After 16 weeks of study, the cortical bone area and periosteal bone formation rate were higher only in the EX than in the CON group. In the L-5 vertebra, the labeled surface on the periosteum was higher in the EX and the bone formation rate on the endocortical surface was higher in the GH than in the CON group. However, there was a negative interaction when the two interventions were combined. We conclude that a low-dose of growth hormone administration could initially potentiate long bone response to exercise. However, from the present study, long-term treatment with low-dose growth hormone administration does not enhance the increase in bone mass from exercise.

Analysis of Variance↗
PubMed1994

Effects of 17 beta-estradiol replacement and treadmill exercise on vertebral and femoral bones of the ovariectomized rat.

To evaluate the effect of 17 beta-estradiol replacement (10 micrograms, twice a week) (E2) and treadmill exercise (18 m/min, 45 min/day) (EX) on long bone and vertebral bone mass and density, 10-month-old rats were ovariectomized (OV) and divided into four groups: OV, OV + E2, OV + EX, OV + EX + E2 2 months after surgery. After 7 weeks intervention, the calcium content and the density of lumbar-5 were higher in both OV + E2 and OV + EX + E2 groups than in the OV group, but, only the OV + EX + E2 group had a significantly higher femoral bone weight and density than the OV group. After 16 weeks intervention, the bone-conserving effects of E2 and EX were significant on lumbar-5 and femoral dry weight and density. The effect of E2 on both two sides of bones was due to the suppression of the bone turnover rate, while EX suppressed bone turnover rate primarily on the femur. We conclude that the effect of the two interventions on lumbar-5 and femoral bone mass were additive and independent.

Acid Phosphatase↗
PubMed1994

Effect of growth hormone administration and treadmill exercise on serum and skeletal IGF-I in rats.

Growth factors may be mediators of local and systemic factors that enhance bone formation. This study examined the effect of treadmill exercise and ovine growth hormone administration on levels of insulin-like growth factor I (IGF-I) in serum (ng/ml), long bone, and vertebrae and on bone formation rate. Forty female rats were divided into four groups: control; exercise (17 m/min, 1 h/day); growth hormone (0.05 mg.100 g-1.day-1); growth hormone plus exercise. After 9 wk of study, the serum levels of IGF-I were higher in the intervention groups than in the control group; however, the IGF-I concentration and the periosteal bone formation rate in the long bone were significantly higher only in the exercised rats. The IGF-I concentration and the cancellous bone formation rate in the vertebrae did not differ among the experimental groups. The vertebral and long bone formation rate were correlated with bone concentrations of IGF-I. Serum levels of IGF-I were also correlated with serum osteocalcin and the long bone formation but not with the vertebral bone formation. The association of bone formation with serum and bone IGF-I supports the suggestion that IGF-I is one of the growth factors that regulate bone formation, in particular as a mediator of the response of bone to exercise.

Analysis of Variance↗
PubMed1994

Effect of growth hormone administration and treadmill exercise on the body composition of rats.

The aim of this study was to compare the effects of growth hormone administration and treadmill exercise on bone mass, body fat mass, and fat-free mass. Forty female rats aged 14 mo were divided into control, ovine growth hormone administration (0.5 mg.kg-1.day-1; GH), treadmill exercise (17 m/min, 60 min/day; EX), and EX + GH groups. Noninvasive total body electrical conductivity and dual X-ray absorptiometry techniques were used to assess the body fat content, fat-free mass, and tibial and L4 vertebral bone mineral content of each experimental animal at weeks 0, 9, and 16. The age-related increase in body fat mass was suppressed in the GH group, and the fat-free mass and L4 bone mass were higher in the GH group than in the control group. Conversely, in the EX group there was no gain in body fat mass and no significant change in fat-free mass or vertebral bone mass. The tibial bone mass increased in both the GH and EX groups; however, the time response to the two interventions appeared to differ. In the EX + GH group there was no further enhancement of the anabolic effect on the tibial bone mass. The effect of growth hormone administration on body fat content and bone mass is distinct from that of treadmill exercise.

Absorptiometry, Photon↗
PubMed1993

Influence of exercise on cancellous bone of the aged female rat.

Dual-energy x-ray absorptiometry and dynamic histomorphometry were used to examine the effect of treadmill exercise on the bone density and cancellous bone formation and resorption in the proximal tibia and fifth lumbar vertebra (L5) of the aged female rat. Female rats aged 14 months were divided into four groups: 8 controls and 10 exercised for a 9 week study and 8 controls and 9 exercised for a 16 week study. Exercise consisted of running on a flat-bed treadmill, 17 m/minute, 1 h/day, 5 days/week. Tibial metaphysis and L5 vertebral density of each rat were measured in the 16 week study by DXA at weeks 0, 9, and 16. Compared to the control group, a significant increase in bone density in both metaphyseal tibia and L5 vertebra was apparent at 16 weeks after exercise training (P = 0.046 and 0.025, respectively, by two-way ANOVA). Histomorphometric analysis showed that the trabecular bone eroded surface and the ratio of eroded to mineralizing surface in tibial metaphysis were significantly lower in the exercised than in the respective control group in both the 9 and 16 week studies. In L5 vertebra, these decreases by exercise were apparent only in the 16 week study. A significant increase in the bone formation rate was apparent in the cancellous bone of the tibia but not of the vertebra after 16 weeks of exercise (P < 0.05). The trabecular architecture (bone number and separation) of the L5 vertebra in the exercised rats did not differ from that of the controls in either study.(ABSTRACT TRUNCATED AT 250 WORDS)

Absorptiometry, Photon↗
PubMed1992

Hip fracture patients have generalized osteopenia with a preferential deficit in the femur.

Bone density was measured in 31 white women with hip fractures by single- and dual-photon absorptiometry at the radius, lumbar spine and proximal femur. The mean age was 71.4 years. Comparison with premenopausal normals revealed Z-scores as follows: radius, -1.75; spine, -1.45; femoral neck, -2.40; Ward's triangle, -2.41; and trochanter, -1.42. These values altered when calculated for the patient's age by the use of sex- and race-specific regressions against age in a healthy, non-fracture population. The age-corrected Z-scores were as follows: radius, -0.09; spine, -0.18; femoral neck, -0.79; Ward's triangle, -0.44; and trochanter, -0.80. Thus, although our patients had absolute osteopenia at all skeletal sites when compared with young normals, when compared with age-matched normals (relative osteopenia) the only site with a noticeable deficit was the femur. Interpretation of the extent of osteopenia by comparison with young normals may lead to different conclusions than when an age-matched population is used. Patients with hip fractures had a preferential deficit in density of the femur when compared with normal women of their age.

Absorptiometry, Photon↗
PubMed1992

Preferential osteopenia in women with osteoporotic fractures.

One-hundred thirty-six women with spontaneous vertebral crush fractures had bone density measurements by photon absorptiometry. Their absolute and relative extent of osteopenia were expressed as Z scores with respect to values from normal white women. Absolute Z scores were used to express the mean bone mass of women with crush fractures vis-a-vis normal women at peak bone mass; relative Z scores were used to express the same means vis-a-vis age-matched controls. The skeletal sites measured included the distal radius, lumbar spine, and three sites on the femur (neck, Ward's triangle, and trochanter). The absolute deficit for the five sites ranged from -1.66 to -2.60. The relative deficit was close to 1 SD for all sites. A discriminant analysis revealed that the spine and femur were predictive for vertebral crush fractures but the radius was not. Comparison with a previously reported hip-fracture population (n = 31) showed that the low bone density of the spine separated the two fracture groups best. We propose the following: (a) vertebral-fracture patients have extensive generalized osteoporosis including the hip with a preferential deficit in the spine and (b) hip-fracture patients have generalized osteoporosis with preferential osteopenia of the hip and do not have a greater mineral deficit in the spine or radius than age-matched normal women. It may be that if a single site is to be selected for screening for spine and hip fractures, the greatest value would be in measurement of the femur, although ideally the skeletal site of interest would be measured. Prospective studies are needed to confirm the utility of measurements at the spine and hip in prediction of future fractures.

Absorptiometry, Photon↗
PubMed1991

Biochemical short-term changes produced by hormonal replacement therapy.

Seventy-one white women within 6 months to 6 years postmenopause were randomly assigned to three treatment groups: (a) placebo, (b) calcium, (c) cyclic estrogen-progestin plus calcium. Calcium was given as calcium carbonate with meals to attain an intake of 1,700 mg daily in the latter two groups. All women received 400 IU of vitamin D daily. Samples were obtained at baseline and after 2 months therapy. The hormonal treatment group had a decline in serum calcium, osteocalcin and urinary hydroxyproline and an increase in levels of calcitonin, parathyroid hormone and calcitriol. The increase in the latter two measurements could have resulted from the drop in serum calcium, it is also possible that the increase in calcitonin levels was a result of calcium supplementation. Although all these changes were statistically significant for the estrogen treatment group when considered alone, analysis of variance including the 3 groups demonstrated significance for the estrogen group for the parameters of skeletal metabolism but not for the changes in the calciotrophic hormones. There was an increase in serum calcium (p = 0.05) in the calcium augmentation group. It would be of interest to determine the effects of higher intakes of calcium in both the calcium and the estrogen treatment groups and to further explore differences in effects on bone remodeling between the two treatment approaches as well as the possibility of a additive effects. Early effects of estrogen replacement reduce bone remodeling whereas calcium supplementation to 1,700 mg per day of Ca CO3 did not appear to affect the parameters of bone remodeling.

Bone Remodeling↗
PubMed1991

Effect of physical activity on the metabolism of magnesium in the rat.

The influence of exercise and immobilization on magnesium (Mg) balance, as influenced by vitamin D, was evaluated in female Sprague-Dawley rats that were divided into four groups: exercised fed ad libitum, pair-fed exercised, immobilized, and control. After 9 weeks, Mg absorption and retention were higher in the exercised groups than in the control group; however, immobilization resulted in an increase in the urinary excretion of Mg and a negative Mg balance. Serum levels of 1,25-dihydroxyvitamin D [1,25(OH)2D] were higher in the exercised group than in the control group. The tibial content of Mg was higher in both exercise groups and lower in the immobilized than in the control group. In an additional experiment to evaluate the Mg balance during early adaptation to exercise training, no change was seen in Mg absorption and balance during the first 5 weeks of exercise, although serum levels of 1,25(OH)2D increased significantly. Immobilization resulted in a decrease in Mg retention without any effect on intestinal absorption. Urinary Mg was consistently higher in the exercised and immobilized groups than in the control group. Prolonged exercise training, after adaptation, increases and longer immobilization decreases intestinal absorption and retention of Mg. The influence of physical activity on Mg absorption is not necessarily mediated by vitamin D. Physical activity may influence mineral absorption by a mechanism associated with growth.

Animal Feed↗
PubMed1991

Relationship of menopause to skeletal and muscle mass.

Cross-sectional and longitudinal changes in body composition with age were examined in white women to determine the relationship of body cell mass to menopause and of body fat to bone mass. There was statistical evidence for a curvilinear component to loss of total body potassium with negligible rates of loss before menopause. Longitudinal measurements also indicated a relationship between the proximity to menopause and the rate of loss of potassium. Total body potassium was significantly related to total body calcium and bone density of the spine, radius, and femoral neck. Total body fat was not related to any of these measurements. We found no evidence that adiposity plays a major role in protecting against bone loss.

Adipose Tissue↗