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Biomedical subjects

L F Villa

Publications and source records attributed to L F Villa.

At least 73 records · Page 4Linked to original sources
PubMed1994

The four-compartment models in body composition: data from a study with dual-energy X-ray absorptiometry and near-infrared interactance on 815 normal subjects.

With the aim of studying body composition according to a four-compartment model in different age groups of healthy subjects, total body water (TBW), body fat (BF), lean body mass (LBM), and total-body bone mineral content (TBBMC) were estimated with dual-energy x-ray absorptiometry (DEXA) and near-infrared interactance in 308 normal males and 507 normal females aged 15 to 83 years. Subjects were divided into 5-year groups up to the age of 50, and then into 10-year groups. In both sexes, BF showed a positive correlation with age (P < .001) and was higher in females aged 40 to 44 compared with younger groups. LBM decreased with age only among males (P < .05). A similar finding was observed with TBW. TBBMC values did not differ between sexes in the 15- to 19-year-old group, and were greater in males in the remaining age groups. This parameter did not vary among females until menopause, and decreased in the 50- to 59-year-old group (P < .001) and from the age of 60 onward (P < .001). Height decreased (P < .001) and weight increased with age (P < .001). Both in male and female groups height and weight correlated with TBBMC (P < .001). When corrected for weight, TBBMC did not vary except in men older than 50, who showed lower values (P < .005). When corrected for height, TBBMC only changed in women aged 30 to 34 and 35 to 39.(ABSTRACT TRUNCATED AT 250 WORDS)

Absorptiometry, Photon↗
PubMed1994

Determinants of total-body and regional bone mineral content and density in postpubertal normal women.

Some investigators consider body fat the main determinant of bone mass in women, and others, weight. Although genetics may be the primary determinant of peak bone mass, modifiable secondary factors such as nutrition and hormone exposure may significantly affect bone mass accretion during the second decade of life. To determine the principal determinants of bone mass, we analyzed total and regional bone mass (by dual-energy x-ray absorptiometry), weight, height, percentage body fat, and lean body mass in a group of 50 young women ranging in age from 14 to 18 years. Total-body bone mineral content, total-body bone mineral density, and total-body bone mineral density corrected for height, analyzed by multiple correlation, were not related to percentage body fat, although percentage body fat did correlate with the regional bone mineral content of the trunk (P < .001), legs (P < .01), and pelvis (P < .001). Lean body mass correlated with total-body bone mineral content and density, total-body bone mineral density corrected for height (P < .001), and regional bone mineral content of the trunk (P < .05), arms (P < .01), and legs (P < .001), but not with regional bone mineral content of the pelvis and head. Weight correlated significantly (P < .001) with all bone mass measurements except regional bone mineral content of the head, where the significance was P less than .05. Similar results were obtained by multiple regression analysis. These results indicate that weight, not body fat, is the main determinant of bone mass in postpubertal women.

Absorptiometry, Photon↗
PubMed1994

Quantitative peripheral computed tomodensitometric study of cortical and trabecular bone mass in relation with menopause.

Changes in total, cortical and trabecular bone mass were studied using quantitative peripheral computed tomodensitometry on the forearm of 58 normal eugonadal premenopausal women and 116 normal postmenopausal women to evaluate the evolution of bone components with age. In premenopausal women, no changes were seen in any bone component. In postmenopausal women, only trabecular bone mass diminished in the first 5 years after menopause (P < 0.05). It continued to decrease in the next 5 years (P < 0.05), but not later. Cortical bone mass experienced a significant loss 6-10 years after menopause (P < 0.001), and more than 15 years after menopause (P < 0.0005). These results are similar to those obtained with other techniques, and document the differing behavior of the cortical and trabecular bone components with years of menopause.

Adolescent↗
PubMed1994

Ultrasound bone velocity and metacarpal radiogrametry in hemodialyzed patients.

Bone density measurements based on the rate of propagation of ultrasound waves provide information on bone elasticity, which is largely dependent on cortical bone structure. Both bone density and cortical bone present variations dependent on age and sex. As far as we know, bone elasticity in patients on hemodialysis has not been studied, so we used ultrasound bone velocity and metacarpal radiogrametry to study 23 adult patients with end-stage renal disease. The patients' results were compared with those of a group of 23 healthy subjects matched by age and sex. The measurements obtained by both ultrasound bone velocity and metacarpal radiogrametry were lower in hemodialyzed patients (p < 0.025) than in controls and there was a good correlation between the two measurements (r2 = 0.561; p < 0.0007). Neither of the measurements correlated with age or time on dialysis. These results show that bone elasticity in dialyzed patients is diminished, which could be an important factor in the bone lesions of these patients.

Adult↗
PubMed1994

Total and regional bone mineral content in primary hyperparathyroidism: sex differences.

Changes in cortical and trabecular bone mass occurring in primary hyperparathyroidism are the subject of controversy. We measured the total and regional bone mass in a group of patients and controls and analyzed the observed changes with respect to sex and other characteristics. Parathormone, serum calcium, serum phosphorus, tubular resorption of phosphates, alkaline phosphatase, and tartrate-resistant acid phosphatase differed significantly (p < 0.001 for all) between patients and controls. All the patients had significantly less total and regional bone mass; the regional bone mass of the arms did not differ. When analyzed according to sex, we found that women had a significant reduction in bone mass in all the zones studied (p < 0.001), whereas men had a significant decrease in bone mass only in the head (p < 0.025). Our findings show that hyperparathyroidism is accompanied by a loss of bone mass except in the arms, and that predominantly both cortical bone (legs, pelvis and skull) and trabecular bone (trunk) are affected. This means that the skeleton suffers generalized bone loss and a significant reduction in total body calcium content. Although we did not study many men, their bone involvement was less intense, and there was a clear difference between the sexes in this respect.

Aged↗
PubMed1993

Biochemical markers of nutrition in osteoporosis.

Thirty-six women with vertebral osteoporosis showed significantly decreased levels of biochemical markers of nutrition, transferrin (P < 0.001), prealbumin (P < 0.001), retinol binding-protein (P < 0.001), and fibronectin (P < 0.001), compared with 40 healthy women of similar age. Multiple regression analysis showed a significant (R2 = 0.509; P = 0.0068) correlation between bone mineral content and biochemical markers of nutrition in the osteoporotic patients but not in the control group. These data suggest that postmenopausal osteoporosis may be associated with a nutritional deficiency.

Aged↗
PubMed1993

Bone changes in postmenopausal Spanish women.

Total body bone mass (TBBM), axial bone mass (trunk = chest and spine), and peripheral bone mass (arms and legs) were determined in 258 normal, slow bone mass loser, postmenopausal women, as determined by previous biochemical studies, in order to study the degree of bone mass reduction due to menopause. The subjects of this study were divided into 5-year groups on a year-since-menopause basis. The first group corresponded to 1-5 years since menopause, and the last group to 25 years or over since menopause. An important and significant reduction in trunk bone mass (-12.3%, P < 0.001) and TBBD (-5.8%, P < 0.002), without changes in head, arms, and legs was observed in the first 5-year group. In the next 5-year group, a significant reduction was observed in all body areas, but at a higher rate in the peripheral skeleton (-9% in arms and -7.3% in legs). A slow down in bone mass loss was observed in the period between 10 and 25 years since menopause. These values became significant again after 25 years since menopause at the axial (-28.9%, P < 0.001) and TBBD (-20.3%, P < 0.05) level. Aside from providing percentages of bone mass reduction with respect to age and time since menopause, these data also indicate that measurements of specific body areas may not be extrapolated to others due to different loss in different body areas, and that there is a marked bone loss rate in the axial skeleton in the first 5 years since menopause.

Absorptiometry, Photon↗
PubMed1993

Total and regional bone mineral content in women treated with GnRH agonists.

Changes in bone mineral content induced by GnRH agonists were investigated by measuring total body bone mineral content (TBBM) and regional bone mineral content (BMC) (arms, legs, trunk, pelvis) and densities with dual energy X-ray absorptiometry in 25 premenopausal women before and after a 6-month treatment with gonadotropin-releasing hormone (GnRH) agonists. Biological markers of bone remodeling, estrogens, luteinizing hormone, and follicle-stimulating hormone were also measured. Weight and body mass index increased significantly after treatment (P < 0.05), and TBBM, corrected for weight (TBBM/W), decreased (P < 0.001). The changes in BMC that we observed ranged from +2.5% to -6.9%. The greatest decrease in regional BMC occurred in the trunk (4.4%, P < 0.001), with TBBM decreasing by 2.1% (P < 0.001). No significant changes were observed in the limbs. Tartrate-resistant acid phosphatase (TRAP) increased significantly after treatment (P < 0.001) and a significant negative correlation between TRAP and TBBM (P < 0.001) and between TRAP and estradiol (P < 0.001) were observed before treatment. The lack of changes observed in the BMC of the limbs indicate that GnRH agonists cause a preferential loss of BMC in trunk osseous structures, a situation similar to that of the first years of menopause.

Absorptiometry, Photon↗
PubMed1993

Beta 2-microglobulin in postmenopausal osteoporosis.

The so-called bone-derived growth factor, or beta 2-microglobulin, has a regulatory function in bone metabolism, stimulating osteoclastic activity. Osteoclastic activity is enhanced in postmenopausal osteoporosis, suggesting that beta 2-microglobulin concentration may also be increased in this disease. beta 2-microglobulin concentration was found to be raised (P < 0.001) in 30 women with postmenopausal osteoporosis as compared with 30 normal women of similar age; tartrate-resistant acid phosphatase concentration also was raised (P < 0.001), and total body bone mineral content was decreased (P < 0.001). Linear regression analysis revealed a highly negative correlation result between total body bone mineral content and beta 2-microglobulin (r = 0.577, P < 0.001), and a positive correlation result between beta 2-microglobulin and tartrate-resistant acid phosphatase concentration (r2 = 0.806, P < 0.001). These findings, and the stimulatory effect of beta 2-microglobulin on osteoclastic and osteoblastic activity, suggest that beta 2-microglobulin may play an important role as a local regulatory factor in the pathogenesis of postmenopausal osteoporosis.

Acid Phosphatase↗
PubMed1993

Age-related differences in total and regional bone mass: a cross-sectional study with DXA in 429 normal women.

Total body bone mineral content (TBBMC), total body bone mineral density (TBBMD) and regional bone mineral content (BMC) and density (BMD) were assessed by dual-energy X-ray absorptiometry (DXA) in 429 normal women aged 15-83 years, of whom 242 were premenopausal and 187 postmenopausal. The population was divided into 5-year age groups. In the premenopausal women no changes in TBBMC, TBBMD or regional BMC and BMD were observed with age, and TBBMC and TBBMD values correlated well with body weight (p < 0.001). Postmenopausal women showed an overall reduction in bone mass (p < 0.001), more marked at the axial level than peripherally (1.6% vs. 0.8%/year). The values of TBBMC and TBBMD correlated well with chronological age, time since the onset of menopause and body weight (p < 0.001). In these women age did not correlate with body weight, which suggests that postmenopausal bone mass loss depends more on chronological age and time since the onset of menopause than on other variables. The stability observed in bone mass values from ages 15-19 to menopause highlights the importance of stimulating the acquisition of an appropriate peak bone mass in women before adolescence begins.

Absorptiometry, Photon↗
PubMed1993

Bone mineral content and anthropometric variables in men: a cross-sectional study in 324 normal subjects.

Total body bone mineral content (TBBMC), total body bone mineral density (TBBMD), and regional bone mineral content (BMC) were determined with dual energy X-ray absorptiometry and correlated with different anthropometric variables in 324 normal male subjects aged 15 to 85 years, in order to obtain further knowledge of the controversial course of bone mass in males. These subjects showed increased TBBMC and TBBMD up to the age of 25-29 years. A positive and significant (p < 0.001) correlation was observed between TBBMC and TBBMD and with BMC with age (p < 0.001), as well as between age and body weight (p < 0.001) and between the latter and body fat (p < 0.001). Age did not correlate with weight or TBBMC, TBBMD, and regional BMC in subjects older than 29 years, while a significant and positive correlation between body weight and muscle mass was observed with bone mass (p < 0.001). By multiple regression analysis, TBBMC was significantly independent of fat-free mass (FFM) and lean body mass (LBM) (p < 0.01). These findings led us to point out that bone mass increases until the age of 29 years and that changes depend more on weight that on age in men. The rate of bone mass loss with age was 0.23%, that of soft tissue 0.35%, while fat mass increased 0.7% per year.

Adolescent↗
PubMed1993

Body composition in children and Tanner's stages: a study with dual-energy x-ray absorptiometry.

Total body bone mineral content (TBBM), body fat content (BF), and fat-free mass (FFM) were measured in 154 children using dual-energy x-ray absorptiometry (DEXA). Total body calcium level (TBCa) was calculated from TBBM. Children were divided into groups according to Tanner's stages 1, 2, 4, and 5. Children in stage 3 were not included in the study in order to better differentiate between prepubertal and postpubertal individuals. We did not find differences in TBBM, TBCa, BF, and FFM between Tanner's stages 1 and 2 or between sexes. TBBM and TBCa in stages 4 and 5 were lower in girls than in boys (P < .001 and P < .01, respectively); no differences were observed between girls of both groups, although boys showed significant differences (P < .05). FFM for both sexes was lower in stages 1 and 2 than in stages 4 and 5. Girls showed lower FFM (P < .001) than boys in stages 4 and 5; FFM was higher in boys in stage 5 than in those in stage 4 (P < .005), and the same was true for girls (P < .002). Boys in stage 4 had less BF than girls (P < .005), and the same was true for stage 5 (P < .001). Girls in stages 4 and 5 had greater BF than those in stages 1 and 2 (P < .001). These differences suggest that as boys go through puberty, both TBBM and FFM continue to increase, while in girls only BF and FFM increase. These data indicate clear sex differences in somatic postpubertal development.

Absorptiometry, Photon↗
PubMed1993

Four-compartment model of body composition of normal elderly women.

A group of 186 apparently normal women was divided into three age groups (average ages 65.3 +/- 4.4, 74.7 +/- 5.5, and 80.9 +/- 4.2 years, respectively) and their body composition was studied using dual-energy X-ray absorptiometry. The fat, fat-free, and mineral components were quantitated, and the fat-free compartment was calculated to define a four-compartment model of body composition (fat, fat-free, mineral, and water). Fat decreases with age, as shown by the comparison of the group whose average age was 75 years with the 65-year-old group (p < 0.01) and 80-year-old group (p < 0.005). Soft-tissue mass was greater in the 80-year-old group (p < 0.025) than in the 75-year-old group. Water was lower in the two older groups (p < 0.02 and p < 0.005, respectively), and the mineral component showed no differences. The decreased fat, increased soft tissues, and absence of changes in the mineral component may be related to an improvement in habits and lifestyle in recent years.

Absorptiometry, Photon↗
PubMed1993

Body composition in postpubertal boy cyclists.

Twenty-two young male cyclists aged 15 to 19 years (mean 16.2 +/- 0.4 years) were studied in order to assess the effect of physical training on the body composition of adolescents. The subjects had been training on the road 10 hours per week for over 2 years, and were compared to 22 sedentary normal subjects of similar age range (mean 16.9 +/- 0.3 years). Food and calcium intake was similar in both groups. The total body bone mineral content and total body bone mineral density were lower in the group of cyclist adolescents (p < 0.05 respectively). There were no differences in height, weight, corporal index, percent body fat, fat-free mass and soft tissue mass between groups. Our results suggest that cycling in male adolescents may be associated with a lower bone mass gain. In our opinion, the recommendable nature, quantity and quality of exercise at these ages must be better defined, through additional experimentally-designed studies, in order to prevent negative effects over bone mass gain.

Absorptiometry, Photon↗
PubMed1993

A longitudinal study of total and regional bone mineral content and biochemical markers of bone resorption in patients with idiopathic hypercalciuria on thiazide treatment.

The effect of thiazides on total body bone mineral content and axial (trunk) and peripheral (arms) bone mass was evaluated. First, dual-energy X-ray absorptiometry was used to study bone mass in 24 patients with idiopathic hypercalciuria and in 22 healthy subjects. Next, the patients were randomized into a group of 14 patients treated with chlorthalidone (50 mg/day) and a group of 10 untreated patients who served as controls; in these two groups biochemical and bone mass studies were repeated 1 year later. Compared with healthy controls, patients with idiopathic hypercalciuria had less bone mass in total body (p < 0.02), arms (p < 0.001), and trunk (p < 0.05). After 1 year, the group of patients treated with thiazides manifested an increase of bone mass in total body (p < 0.0045), arms, and trunk (p < 0.0001) and a decrease in 24-hour calciuria, urinary calcium/creatinine ratio, and serum tartrate resistant acid phosphatase concentration; the untreated group of patients lost bone mass in all three sites. Under baseline conditions, the groups of treated and untreated patients exhibited a negative linear regression between total body bone mass and both urinary calcium/creatinine (r2 = 0.234; p < 0.001) and serum tartrate resistant acid phosphatase concentration (r2 = 0.399; p < 0.0001). Our results confirm the favorable effect of thiazides on bone mass and provide evidence of enhanced bone remodeling in idiopathic hypercalciuria.

Absorptiometry, Photon↗
PubMed1993

Total and regional bone mass values and biochemical markers of bone remodeling in endometriosis.

OBJECTIVE: TO measure peripheral, axial, and total bone mass and to assess markers of bone remodeling in women with endometriosis, with the aim of addressing previous reports of diminished peripheral bone mass in these patients. METHODS: Whole body bone densitometry, estradiol (E2) levels, and biochemical bone markers (calcium, phosphorus, total alkaline phosphatase, tartrate-resistant acid phosphatase, and total proteins) were determined in 28 patients with endometriosis and compared with findings in 33 controls. RESULTS: There were no significant differences between the groups in bone mass at different sites or in biochemical bone markers. We observed a significant negative correlation between tartrate-resistant acid phosphatase and E2 levels (P < .001) and with total (P < .001), head (P < .01), and axial (trunk) (P < .001) bone mass. Total alkaline phosphatase did not correlate with any of the indices studied. CONCLUSIONS: Bone mass was not lower in any of the areas studied in women with endometriosis. There was a significant negative correlation of tartrate-resistant acid phosphatase with E2 and with total, head, and trunk bone mass.

Absorptiometry, Photon↗
PubMed1992

[The 4-component model of body composition].

BACKGROUND: Given the importance of knowing the corporal composition according to the model of the four components (fat, mineral, fat free and aqueous) the same was calculated in 220 women and 130 men, considered as normal, between the ages of 15 and 49. METHODS: The corporal components were determined with double energy x-ray densitometry with the component corresponding to water being obtained from the fat free component, thereby evaluating the four principal parts of corporal composition. RESULTS: In the men all of the values except those of fat were greater than in the women (p less than 0.001), with the fat in the latter being (p less than 0.001). The values of mineral content demonstrated sexual differences in reaching of the peak of osseous mass and were maintained stable in women up to the age of 49. CONCLUSIONS: With regards to the mineral component, there is a sexual difference in achieving the maximum value. While the fat values in men are super-impossible to those referred in the literature for ther media and with other techniques they are not so in women, in whom superior values are observed leading to reanalysis of how the physical constitution, habits and way of life of women in this country may have repercussions in this sense.

Absorptiometry, Photon↗