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C Formica

Publications and source records attributed to C Formica.

16 recordsLinked to original sources
PubMed1996

Effects of insulin on body composition in patients with insulin-dependent and non-insulin-dependent diabetes.

Insulin is used to control blood glucose but may have an adverse effect on the amount and distribution of fat mass and other cardiovascular risk factors. To test this hypothesis the effect of insulin therapy on blood glucose, body composition, and lipid levels was measured during 6 months in 9 patients with newly diagnosed insulin-dependent (Type 1) diabetes mellitus (IDDM) and 15 patients with non-insulin dependent (Type 2) diabetes (NIDDM) and secondary failure of therapy with oral hypoglycaemic agents. Both groups received similar daily doses of insulin (approximately 0.6 units kg-1 day-1). Glycaemic control improved during 6 months treatment in both groups, although the reduction in HbA1c was greater in IDDM (5.2 +/- 0.7%) than in NIDDM (2.0 +/- 0.4%, p < 0.001). All parameters of the lipid profile improved in IDDM but not in NIDDM. Body weight, lean mass, and fat mass, measured by dual energy x-ray absorptiometry, increased at 1 month in IDDM but not in NIDDM. By 6 months, body weight had increased more in IDDM than NIDDM (9.1 +/- 1.2 vs 3.77 +/- 0.5 kg, p < 0.01). The increase in weight was predominantly lean mass in IDDM (60.4 +/- 9.3%) and fat mass in NIDDM (59.9 +/- 8.4%). The increase in lean mass was greater in IDDM than NIDDM (5.6 +/- 1.1 vs 1.4 +/- 0.3 kg, p < 0.001). Fat mass increased by similar increments in IDDM and NIDDM (3.4 +/- 0.8 vs 2.4 +/- 0.5 kg, p = ns) and was predominantly an increase in trunk fat (IDDM: 2.3 +/- 0.6 kg, NIDDM: 2.0 +/- 0.4 kg, p = ns). The central/peripheral fat mass ratio prior to treatment was lower in IDDM than NIDDM (0.64 +/- 0.05 vs 1.09 +/- 0.09, p < 0.01) and then increased in IDDM by 0.32 +/- 0.15 (p = 0.07) and in NIDDM by 0.22 +/- 0.06 (p < 0.001). In conclusion, insulin therapy is associated with weight gain in both IDDM and NIDDM. In the former, weight gain reflects increases in lean mass whereas in NIDDM it reflects an increase in trunk fat mass. It remains to be determined whether this trend to central obesity partly offsets other benefits of insulin therapy in NIDDM.

Adipose Tissue↗
PubMed1996

Do genetic factors explain associations between muscle strength, lean mass, and bone density? A twin study.

Are the associations between muscle strength, lean mass, and bone mineral density (BMD) genetically determined? Based on within-pair differences in 56 monozygotic (MZ) and 56 dizygotic (DZ) female twin pairs, mean age 45 yr (range 24-67), BMD was associated with lean mass, independent of fat mass and height (P < 0.05). A 10% increment in femoral neck (FN) BMD was associated with a 15% increment in lean mass (approximately 6 kg). BMD was associated with muscle strength (measured in 35 pairs) before, but not after, adjusting for lean mass. Based on age-adjusted cross-sectional analyses, same-trait correlations (+/- SE) in MZ pairs were double those in DZ pairs: FN BMD (0.62 +/- 0.08, 0.33 +/- 0.12) and lean mass (0.87 +/- 0.03, 0.30 +/- 0.11; all P < 0.001), consistent with a genetic hypothesis. The cross-trait correlation (r) between lean mass and FN BMD in the same individual was 0.43 +/- 0.06. The cross-trait cross-twin correlation between lean mass in one twin and FN BMD in the other was 0.31 +/- 0.07 in MZ pairs, approximately 75% of the cross-trait correlation (r) and 0.19 +/- 0.09 in DZ paris (P < 0.001). After adjusting for height and fat mass, the MZ and DZ cross-trait cross-twin correlations were no different (0.16 +/- 0.08 and 0.13 +/- 0.09, respectively). Therefore, genetic factors account for 60-80% of the individual variances of both FN BMD and lean mass, and > 50% of their covariance. The association between greater muscle mass and greater BMD is likely to be determined by genes regulating size.

Adult↗
PubMed1996

Dual-energy X-ray absorptiometry body composition model: review of physical concepts.

Although dual-energy X-ray absorptiometry (DXA) is widely used in clinical research as a means of quantifying body composition, there remains at present little published information that reviews the method's underlying physical basis. Because a clear understanding of DXA physical concepts is integral to appropriate use and interpretation, we present here a three-section review that includes both relevant in vitro and in vivo experimental demonstrations. In the first section we describe the main physical principles on which DXA is based. The section that follows presents a step-by-step analysis of the DXA two-component soft tissue model. In the final section we demonstrate how knowledge of physical concepts can lead to resolution of important methodological concerns, such as the influence of hydration changes on DXA fat estimates. A thorough understanding of DXA physical concepts provides a basis for appropriate interpretation of measurement results and stimulates many new and important research questions.

Absorptiometry, Photon↗
PubMed1995

Inhomogeneity in body fat distribution may result in inaccuracy in the measurement of vertebral bone mass.

When bone mineral content (BMC) is measured by dual X-ray absorptiometry (DXA), the X-ray beam is attenuated by bone and soft tissue. Since the component of the attenuation caused by the soft tissue overlying bone cannot be measured, the attenuation caused by soft tissue adjacent to bone is measured and is used in the calculation of BMC. the assumption underlying this approach is that the amount and composition of this adjacent soft tissue is the same as overlying bone. The aim of this study was to examine the validity of this assumption by determining whether fat distribution over and adjacent to bone differ and whether this introduces accuracy errors in the measurement of BMC by postero-anterior (PA) and lateral scanning. BMC (posterior processes plus vertebral body, g) of the third lumbar vertebra was 17.3 +/- 0.7 by PA and 17. +/- 0.7 by lateral scanning in 27 premenopausal women (p = NS), but 2.7 g or 20% higher by PA than scanning in 27 postmenopausal women (14.4 +/- 0.7, 11.7 +/- 0.5, p<0.01). Thus, the respective diminutions across age by PA scanning was about half that by lateral scanning (16.8 +/- 3.9%, 31.2 +/- 3.0%, p<0.01). Percent fat in the soft tissue baseline (anterior to bone, ST-ant) used to derive BMC by lateral scanning by 2.6 +/- 0.7% in premenopausal women and 7.5 +/- 1.0% in postmenopausal women (both p<0.01). After adjusting for these differences in percent fat, BMC by PA and lateral scanning no longer differed.

Absorptiometry, Photon↗
PubMed1995

Equivalent deficits in bone mass of the vertebral body and posterior processes in women with vertebral fractures: implications regarding the pathogenesis of spinal osteoporosis.

Reduced bone mass of the spine in women with vertebral fractures is attributed to excessive trabecular bone loss from the vertebral body. However, the measurement obtained by posteroanterior (PA) scanning includes the posterior processes and the vertebral body, each comprising about 50% of the total vertebral mass. Thus, the deficit in bone mass by PA scanning may be due to deficits in one or both of these structures. We asked two questions: (1) In healthy women, is the age-related diminution in bone mass of the vertebral body greater than the diminution at the posterior processes? (2) In women with vertebral fractures, is the deficit in bone mass at the vertebral body, the fracture site in spinal osteoporosis, greater than at the posterior processes? Bone mass of the posterior processes and vertebral body of the third lumbar vertebra was measured by lateral scanning using dual-energy X-ray absorptiometry (DXA). Compared with 27 premenopausal women, deficits in 27 postmenopausal women at the posterior processes and vertebral body, respectively, were 35.9 +/- 3.7 and 25.2 +/- 4.1% (p < 0.05); t score, -1.5 +/- 0.2 and -1.1 +/- SD (p = 0.09). Compared with the postmenopausal (age-matched) women, deficits in 21 women with vertebral fractures at the posterior processes and vertebral body, respectively, were 22.6 +/- 4.9 and 24.5 +/- 8.3% (p = NS); Z score, -0.8 +/- 0.2 and -0.8 +/- 0.3 (p = NS). In vivo the bone mass of the vertebral body as a percentage of the whole vertebra was 45.7 +/- 0.1 in premenopausal women, 48.9 +/ 1.9 in postmenopausal women, 51.5 +/- 1.1 in women with low bone mass but no fractures, 52.7 +/- 2.4 in women with vertebral fractures, and 51.9 +/- 2.5% in vitro, based on autopsy specimens from 19 postmenopausal women aged 65 - 95 years. The lower spinal bone density measured using PA scanning in women with spine fractures may not be due to excessive or disproportionate trabecular bone loss from the vertebral body because comparable deficits are found at the posterior processes. Whether these deficits are due to reduced peak bone mass, trabecular bone loss, cortical bone loss, or varying combinations of these mechanisms remains to be established.

Absorptiometry, Photon↗
PubMed1994

Reduced femoral neck bone density in the daughters of women with hip fractures: the role of low peak bone density in the pathogenesis of osteoporosis.

Low bone density in women with hip fractures ("senile" osteoporosis) may be due to excessive bone loss or low peak bone density. If excessive bone loss is responsible, then no reduction in bone density is expected in their daughters. If low peak bone density is responsible, then bone density should also be reduced in their daughters because genetic and family environmental factors influence the variability in bone density. Bone density was measured using dual-photon absorptiometry and expressed as a standardized deviation or Z score relative to 697 controls, adjusting for age, height, weight, and menopausal status. In 74 women with hip fractures, the Z score (mean +/- SEM) was -0.52 +/- 0.14 (P < 0.001) at the femoral neck, -1.04 +/- 0.17 (P < 0.001) at the femoral shaft, and -0.43 +/- 0.10 (P < 0.001) at the lumbar spine. In their 41 daughters, the Z score was -0.40 +/- 0.17 (P < 0.05) at the femoral neck, -0.41 +/- 0.19 (P < 0.001) at the femoral shaft, and 0.23 +/- 0.13 (NS) at the lumbar spine. We conclude that daughters of women with hip fractures are likely to be at increased risk for hip fractures themselves because they have reduced femoral neck bone density. Femoral neck fractures may not be entirely attributable to trauma; reduced bone density is likely to contribute and may be caused by the attainment of a lower peak femoral neck bone density.

Absorptiometry, Photon↗
PubMed1994

Bone density at weight-bearing and nonweight-bearing sites in ballet dancers: the effects of exercise, hypogonadism, and body weight.

Exercise is recommended as a means of preventing osteoporosis. When intensive, weight-bearing exercise is often associated with hypogonadism. As weight-bearing exercise is likely to be more beneficial at weight-bearing than nonweight-bearing sites, and hypogonadism is likely to be more detrimental to trabecular than cortical bone, we tested the hypothesis that exercise and hypogonadism result in differing regional effects: net benefits at weight-bearing, predominantly cortical sites, and net deficits at nonweight-bearing trabecular-rich sites. Bone density (grams per cm2), body fat, and fat-free mass (kilograms) were measured using dual x-ray absorptiometry in 44 ballet dancers, aged 17.0 +/- 0.2 yr (mean +/- SEM), 18 sedentary amenorrheic girls with anorexia nervosa, and 23 girls of comparable age with regular menstrual cycles. Bone density, expressed as a percentage above or below the mean in the girls with regular menstrual cycles, was normal or elevated at weight-bearing sites in dancers [femoral neck, 3.1 +/- 1.7% (P = NS); Wards triangle, 4.1 +/- 2.3% (P = NS); trochanter, 5.9 +/- 1.9% (P < 0.05)] and normal or reduced at these sites in girls with anorexia nervosa [-10.5 +/- 3.8% (P < 0.05), -7.8 +/- 4.3% (P = NS), and -8.7 +/- 4.0% (P < 0.05), respectively]. By contrast, deficits similar to those in girls with anorexia nervosa were found in dancers at nonweight-bearing sites [ribs, -5.7 +/- 0.8% (P < 0.01); arms, -4.6 +/- 1.1% (P < 0.01); skull, -5.9 +/- 1.3% (P < 0.01)] before, but not after, correcting for fat mass. Fat mass was 7.8 +/- 0.4 kg in dancers, similar to that in girls with anorexia nervosa (6.3 +/- 0.7 kg) and lower than that in girls with regular menstrual cycles (16.8 +/- 1.6 kg; P < 0.01). The net result of vigorous exercise, hypogonadism, and leanness in athletic amenorrhea may not be generalized osteoporosis. Weight-bearing exercise may offset the effects of hypogonadism at predominantly cortical weight-bearing sites, such as the proximal femur. Non-weight-bearing sites and weight-bearing sites containing substantial amounts of trabecular bone, such as the lumbar spine, may be adversely affected by hypogonadism while benefiting little from weight-bearing exercise. Deficits at nonweight-bearing sites may be attenuated by maintenance of body weight.

Absorptiometry, Photon↗
PubMed1993

Body composition following hemodialysis: studies using dual-energy X-ray absorptiometry and bioelectrical impedance analysis.

The detection, prevention and treatment of disease is greatly facilitated by the availability of accurate and non-invasive techniques for measuring the amount and regional distribution of fat mass and fat-free mass. As differing degrees of hydration may influence these measurements, we used dual-energy X-ray absorptiometry (DXA) and bioelectrical impedance analysis (BIA) to detect changes in hydration following hemodialysis, and to determine whether fat mass, fat-free mass and bone density measurements were affected by these fluid changes. Ten subjects (7 men, 3 women) mean age 46.2 years (range 25-68 years), with renal failure had bone density, fat-free mass and fat mass measured by DXA, and total body water and fat-free mass measured by BIA, before and after hemodialysis. Thirty-two subjects had fat-free mass measured by DXA and BIA in an attempt to derive new equations (using fat-free mass measured by DXA as the reference standard) to improve the predictive value of BIA. The new equations were then used to derive the changes in fat-free mass following hemodialysis measured using BIA. In absolute terms, total tissue measured by DXA (r = 0.99, p = 0.01) and total body water measured by BIA (r = 0.91, p = 0.01) correlated with gravimetric weight. Following hemodialysis, fat mass and bone density measured by DXA were unaffected by the fluid changes. The change in gravimetric weight was 1.8 +/- 0.3 kg, p = 0.01 (mean +/- SEM). This change was measured as 1.9 +/- 0.3 kg by DXA, -0.9 +/- 1.0 kg by BIA using the published equation for fat-free mass, and 3.2 +/- 0.4 kg using the new equation for fat-free mass.(ABSTRACT TRUNCATED AT 250 WORDS)

Absorptiometry, Photon↗
PubMed1993

Peak bone mass, a growing problem?

The focus of attention in osteoporosis research has been on factors influencing bone fragility and the propensity for trauma (falls) during adulthood and old age. The purpose of this review is to change the focus of this attention toward consideration of skeletal growth in the first 20 years of life and to demonstrate the importance of mineral accrual (and the factors influencing this accrual) in determining bone density in adulthood and old age. We suggest that the epidemiology of fractures may be unified by a central role of reduced peak bone density in the pathogenesis of the low bone density found in patients with fractures. The reduced peak bone density establishes the relevance of age-related and sex hormone-dependent bone loss. Risk and protective factors in the first 20 years of life may have quantitatively larger, and qualitatively different effects on the axial and appendicular skeleton than exposure during adulthood. Public health measures focussed on optimising mineral accrual in the first 20 years of life may be more important than health care measures more proximate to the age at which fractures occur.

Adolescent↗
PubMed1993

Metastatic bone tumors. Nonsurgical treatment. Outcome and survival.

Of 683 (16.1%) consecutive patients investigated from October 1984 to December 1985, 110 had various malignant tumors and secondary bone involvement. In 82 of 110 patients (74.5%), the primary tumor was located in the breast, and the percentage of clinical and radiographic objective responses (OR) of their bone lesions (42.7% and 22.8%, respectively) was higher than for cancer in other sites (clinical OR, 21.4%; radiographic OR, 15.8%). The average survival time of 82 breast cancer patients was 87.4 months, or 38 months from the diagnosis of the bone metastases. Of the 110 patients with bone metastases, 60 patients (54.5%) had secondary spinal involvement. The clinical and radiographic OR (38.4% and 30.2%) were better in the patients with vertebral metastases than in the patients with bone metastases in other sites (clinical OR, 36%; radiographic OR, 9.1%). The average survival time of the patients with vertebral involvement was 99.4 months, or 40.4 months from the time of diagnosis of the bone metastases. From the results obtained, in terms of OR and survival for patients with bone metastases, early and aggressive treatment should be considered to improve the patients' life quality.

Adolescent↗
PubMed1992

Osteoporosis in anorexia nervosa: the influence of peak bone density, bone loss, oral contraceptive use, and exercise.

Anorexia nervosa occurs early in life and predisposes to osteoporosis. Exercise may be protective. We asked: (1) Does failure to attain peak bone density contribute to the deficit in bone density? (2) Does oral contraceptive use protect against osteoporosis? (3) Is any protective effect of exercise confined to weight-bearing sites? Areal bone density (g/cm2) and body composition were measured by dual x-ray absorptiometry in 65 patients with anorexia nervosa and 52 controls. Comparing the 12 patients with primary amenorrhea and the 37 patients with secondary amenorrhea, bone density (mean +/- SEM) at the lumbar spine was 0.88 +/- 0.04 versus 1.06 +/- 0.03 (P = 0.001), respectively. Bone density at the femoral neck was 0.80 +/- 0.04 versus 0.92 +/- 0.03 (P < 0.05), respectively. These values differed before, but not after, adjusting for the respective duration of illness (73.0 +/- 10.3 versus 34.1 +/- 4.8 months, P < 0.001) and fat-free mass (31.6 +/- 1.3 versus 35.4 +/- 0.5 kg, P < 0.01). Bone density at the lumbar spine in the 16 patients with 31.8 +/- 8.3 months of contraceptive exposure was higher than in the 49 patients with no contraceptive exposure (1.14 +/- 0.05 versus 1.02 +/- 0.02 P < 0.02) but was lower than in controls (1.14 +/- 0.05 versus 1.27 +/- 1.02, P < 0.01). No protective effect of contraceptive exposure was detectable at the femoral neck.(ABSTRACT TRUNCATED AT 250 WORDS)

Absorptiometry, Photon↗
PubMed1989

The modified Wagner method for surgical lengthening of the limbs.

The method proposed by Wagner in 1971 for surgical lengthening of the limbs was widely used by the authors for the treatment of dysmetria and (since 1976, for the first time in Italy) for disharmonic hypometria. The limitations of this method were revealed, however, by increasing knowledge in this field and the advent of new biological concepts of bone regeneration. The authors report 51 lengthenings carried out between 1982 and 1987 according to their own modification of the Wagner method. They conclude that the Wagner external fixator associated with corticotomy achieves excellent results, decreasing the number of surgical stages as well as the risk of infection and delay in consolidation.

Adolescent↗