Biomedical subjects
J Zanchetta
Publications and source records attributed to J Zanchetta.
Comparison of morphometric assessment of prevalent vertebral deformities in women using different reference data.
The semiquantitative assessment of vertebral deformities is based on visual evaluation. The quantitative approach is based on different morphometric criteria. This study is aimed at comparing the impact of different reference groups to define normal vertebral shape on the diagnosis of verterbral deformities. Reference normal values were obtained in three groups of women: French, mixed European, and Argentinian. All these women had normal lumbar spine bone mineral density and no vertebral deformities according to the semiquantitative assessment. In a group of 135 women having vertebral deformities according to Genant's semiquantitative assessment, three different morphometric criteria were applied. Morphometric diagnosis disclosed a good agreement with semiquantitative assessment. Agreement of diagnosis was higher for a given cutoff using thresholds obtained in different reference groups (kappa = 0.84-0.96) and lower when different criteria were compared using thresholds obtained in the same reference group (kappa = 0. 75-0.85). When fracture thresholds obtained in three different cohorts were compared separately for the three morphometric criteria, agreement was the highest when the cutoff was based only on the arithmetical mean of vertebral heights and was independent of its standard deviation (SD). Average vertebral height ratios did not differ between the three reference cohorts, whereas SDs of vertebral height ratios were the highest in the mixed European cohort and the lowest in the French cohort (F = 7.41, p < 0.001). In the three groups of women of different nationality, SDs of vertebral height ratios, but not the arithmetical means, were significantly higher in the radiographs of poor quality compared with those of good quality. Thus, the main source of difference of diagnosis was related to different SDs whereas average height ratios were not different. Differences in SDs between the three groups were found to be related, at least partly, to poor quality of radiographs. The impact of the differences between populations seems less important, however, only three countries were compared. These findings suggest that those techniques that take into account the SD of vertebral height ratios will provide different reference values for vertebral morphometry. Because differences in SDs depend mainly on the quality of radiographs, they can be reduced by improving the X-ray technique and by the use of standardized protocols. This variability will result in the identification of a variable number of vertebral deformities in osteoporotic women. These results may be of importance especially for multicentric studies.
Influence of age and sex in serum osteocalcin levels in thoroughbred horses.
In this study, we assessed the potential value of free serum osteocalcin or bone gla protein (BGP), the most abundant non collagenous matrix protein found in bone and dentin, to reflect changes of bone turnover in thoroughbred horses. Levels of osteocalcin were analyzed in serum samples of 54 clinically normal animals divided into three groups (A, B, C) according to age: 8, 16-18 and 24-36 months, in order to determine the standard for young horses of different age and sex. Serum BGP was measured by an in-house developed double antibody radioimmunoassay using bovine antigen. The mean BGP levels (ng/ml) were 45.65 +/- 11.69; 33.65 +/- 16.65; 15.08 +/- 6.70 respectively for groups A, B and C; statistically significant differences were found between groups (A vs B and C; Bvs C). Difference between males and females was found significant in group C with higher values in the females: 18.75 +/- 5.00 against 14.43 +/- 10.47 i n the males. This can be considered a sex related effect on BGP serum levels after the onset of puberty. Correlation coefficient between age and serum BGP for females and males were r 5 20.598 ( P < 0.001) and r 5 200.807 (P < 0.001) respectively. A significant negative linear relationship could be established between these two parameters in males during the growth period. The regression equation between serum BGP and age for males was (month of age = 65.14-1.68. BGP). In the female group the gestation and lactation are variables that lower the correlation coefficient between age and serum BGP levels. These results suggest that serum BGP decreases in thoroughbred horses during the growth period, and significant differences between sexes were found only after the onset of puberty.
[Treatment of post menopausal osteoporosis with intravenous pamidronate in patients with esophagogastric pathology].
Pamidronate is an effective inhibitor of bone resorption; for this reason it is used in the treatment of high bone turnover diseases and osteoporosis. Because of potential gastric and esophagic side effects their oral use is limited in patients with active pathology in these organs. With the aim to evaluate the usefulness and to establish the ideal schedule of treatment of intravenous pamidronate, we assayed pamidronate infusions (APDIV) in 20 postmenopausal women with active gastroesophagical diseases. Ten of these patients received 30 or 45 mg weekly until they achieved an average dose of 157.50 +/- 9.28 mg/year in one month (range: 120-180 mg) (Group A). Another comparable ten women's group received 30 or 45 mg every three months or 90 mg every six months; the achieved average dose in this group was 166.50 +/- 6.87 mg/year (range: 120-180 mg) (Group B). All patients received 1,000 mg elemental calcium daily. Bone mineral density in lumbar spine significantly increased in both groups, but this increment (delta DMO%) was higher in group B. Bone mineral density in femoral neck was only increased in group A. Parathyroid hormone (iPTH) significantly increased at the third month but returned to basal values at the end of the year in both groups. Parameters of bone remodeling such as osteocalcin (BGP), pyridinoline and deoxipyridinolin decreased progressively and remained low at the end of the year. The treatment was well tolerated: only two patients in group A and one in Group B experienced fever and pseudoflu syndrome; phlebitis was present in one patient in the second group. In conclusion, intravenous Pamidronate is an effective and safe treatment for postmenopausal osteoporosis specially in these patients with esophagicor gastric disorders. Future trials are needed to clarify the ideal dose and schedule of treatment.
Tomographic (pQCT) and biomechanical effects of hPTH(1-38) on chronically immobilized or overloaded rat femurs.
Six-month old rats chronically submitted to right hindlimb immobilization (IM) with mechanical overload (OL) of the left leg were treated 1 month later with 200 micrograms/kg/d of hPTH(1-38) for 15 or 75 days. Peripheral quantitative computed tomography (pQCT) scans and bending tests showed that hPTH increased cortical mass and volumetric BMD (vCtBMD) in both legs. However, elastic modulus of cortical bone and diaphyseal load-bearing capacity were improved only in OL bones. Improvement of diaphyseal strength was attributable to that of cortical bone quality, yet a stronger mechanostatic response of cortical modeling to bone material quality was also observed in treated OL bones. Data support hPTH(1-38) use for improving cortical bone mass and strength and point out a physical activity interaction with therapeutic results.
Effects of on/off anabolic hPTH and remodeling inhibitors on metaphyseal bone of immobilized rat femurs. Tomographical (pQCT) description and correlation with histomorphometric changes in tibial cancellous bone.
An anabolic effect of hPTH(1-38) (s.c. doses of 200 micrograms/kg/d during 75 days) on trabecular and cortical bone mass is tomographically described in the metaphyseal region of immobilized rat femurs using pQCT technology, in agreement with previous histomorphometrical studies of the proximal tibial metaphyses. Correlations between pQCT and histomorphometrical data showed that this effect derived from a stimulation of endosteal and trabecular bone modeling that induced a transference from trabecular to cortical bone mass. Loss of effects after withdrawal, resulting from a stimulation of bone remodeling, could be total or partially prevented by subsequent s.c. injections of risedronate (5 micrograms/kg/2/wk), 17-B-estradiol (10 micrograms/kg/d) or calcitonin (10 micrograms/kg/d) given during 60 days, in this order of effectiveness. The preventive potency was proportionally related to the reduction induced in histomorphometric indices of bone resorption.