We investigated 30 consecutive Brazilian patients with definite ankylosing spondylitis (AS) fulfilling the New York and the European spondyloarthropathy study group classification criteria. The mean age at study was 37 years old and the mean disease duration was 17 years. Bone densitometry employed the dual-energy X-ray absorptiometry (DEXA) technique, using a Hologic QDR-1000/W densitometer. Axial bone mineral density (BMD) was measured in the lumbar spine (L1-L4) and appendicular BMD was measured in the total proximal femur and sub-regions (neck, greater trochanter, intertrochanter and Ward's triangle). Based on World Health Organisation criteria, the lumbar spine showed osteopenia or osteoporosis in 50% of the patients, while 86% had osteopenia or osteoporosis in the total proximal femur. When compared with the normal population, the patients showed a significant BMD decrease in the lumbar spine and total proximal femur with sub-regions, except for the femoral neck. A comparison of BMD between patients with active and inactive disease did not reveal a significant effect of clinical disease activity on the lumbar spine and total proximal femur with sub-regions, except for Ward's triangle. Concerning disease chronicity, there were significant positive correlations between disease duration and lumbar spine, total proximal femur, greater trochanter and intertrochanteric regional BMD. This false increase in lumbar spine BMD found mostly in patients with long standing AS was due to the presence of paravertebral calcification and ossification. We conclude that the bone mass loss in AS is better evaluated in the proximal femur, because of the greater sensitivity of bone densitometry in this region, which is almost free of artefacts.

Hereditary 1,25-dihydroxyvitamin D3 [1,25-(OH)2D3]-resistant rickets (HVDRR) is a rare autosomal recessive disorder resulting in target organ resistance to the active form of vitamin D [1,25-(OH)2D3]. Point mutations in the vitamin D receptor (VDR) gene have been identified in HVDRR. We investigated the molecular basis of HVDRR in a Brazilian family with two affected siblings. The propositus is a 12-yr-old boy born to first cousin parents who exhibited the classical pattern of the HVDRR, including early-onset rickets, total alopecia, convulsions, hypocalcemia, secondary hyperparathyroidism, and elevated 1,25-(OH)2D3 serum levels. His younger sister also developed clinical and biochemical features of HVDRR at 1 month of age and died at 4 yr of age. Genomic DNA was isolated from peripheral blood of the boy and from dried umbilical cord tissue of his affected sister. We amplified exons 2 and 3 of the VDR gene, which encode the zinc finger DNA-binding domain by PCR. Direct sequencing of the PCR products revealed a homozygous substitution of cytosine for thymine at nucleotide position 88 in exon 2 of the VDR gene in both affected siblings. This point mutation determined the substitution of a stop codon (TGA) for arginine (CGA) at amino acid position 30 at the first zinc finger of the DNA-binding domain of the VDR. This substitution generated a truncated receptor missing 397 residues. The parents and a normal sister were heterozygous for this mutation. In conclusion, we describe a novel nonsense mutation in the first zinc finger of the VDR that generated a severely truncated form of this receptor.

Bone histomorphometry values for normal individuals within different populations have been well established. We studied iliac crest bone samples from 125 healthy Brazilian subjects. The effect of sex, race, and age variables on histomorphometric parameters was evaluated. Bone volume showed a trend to decrease with age in both sexes, being significantly higher in black females and Caucasian males. Interactions among sex, race, and age had no effect on trabecular thickness (Tb.Th) and trabecular separation (Tb.Sp). However, age had a significant effect on Tb.Th and Tb.Sp, and sex had an impact on Tb.Sp. Trabecular number (Tb.N) was higher in black females than in males and was higher in Asian males than in females. Among females, Tb.N was lower in Asians than in other races and was higher in blacks than in Caucasians and or in those of mulattos. In addition, Tb.N was higher in males under 10 than in males over 50 years old, was higher in females under 10 than in females in any other age bracket, and was lower in females in the 41-50 age bracket than in younger females. Osteoid volume and osteoid surface were significantly higher in males than in females, and a significant age-related difference in osteoid thickness was observed. No significant sex-related or race-related differences were found in terms of resorption, although eroded surface decreased with age. In conclusion, sex, race, and age, as well as interactions among these three variables, were found to affect some static histomorphometric indexes in healthy Brazilian subjects.

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ObjectiveTo validate different methods for estimating HIV/Aids patients' body fat: total body skinfold thickness, central (trunk) skinfold thickness, peripheral (limb) skinfold thickness, waist circumference (WC) and waist-to-hip ratio (WHR). Dual-energy Xray absorptiometry (DEXA) and computed tomography of the abdomen (CTA) were used as the gold standard. Methods An analysis was done on 15 adult HIV/AIDS patients (10 men and 5 women) who were being treated at the AIDS Clinic at a public university hospital, São Paulo, Brazil. Their total subcutaneous fat (TSF) was estimated from the sum of the thicknesses of the biceps, triceps, subscapular, midaxillary, suprailiac, abdominal and medial calf skinfolds. The central subcutaneous fat (CSF) was estimated by summing the subscapular, axillary, suprailiac and abdominal skinfold measurements. The peripheral subcutaneous fat (PSF) was estimated by summing the biceps, triceps and medial calf skinfold measurements. These were compared with DEXA. The WC, WHR and CSF were compared with CTA. In the statistical analysis, the Pearson correlation coefficient (r) and Mann-Whitney test were utilized. Results There was a correlation between fat mass measured by DEXA and by TSF, CSF and PSF, even after adjusting for age (r≥0.80 for all). WC, WHR and CSF presented correlation with total abdominal fat measured by CTA, even after adjusting for age (r≥0.80 for all). ConclusionsThe methods for estimating body fat should be chosen according to the type of fat to be evaluated and can be used in research and healthcare services instead of DEXA and CTA for HIV/AIDS patients.