Transforming growth factor-beta1 gene polymorphism, bone turnover, and bone mass in Italian postmenopausal women.

Transforming growth factor beta1 (TGF-beta1) is abundant in bone and is an important regulator of the osteoclastic-osteoblastic interaction (coupling). The sequence variation, 713-8delC in the TGF-beta1 gene has previously been found to be associated with very low bone mass in osteoporotic women and with increased bone turnover in both osteoporotic and normal women. The possible association of this polymorphism with bone mass and bone turnover has now been investigated in 256 postmenopausal Italian women. A significant association of TGF-beta1 with bone mass was detected in the populations. Subjects carrying the sequence variation 713-8delC (Tt) genotype showed a significantly lower bone mineral density (BMD) at the hip than those without sequence variation in the genotype (TT). Individuals carrying the tt genotype have a more severe osteoporosis (P=0.0001 vs. TT and Tt genotypes). The frequency of the fragility fractures was significantly lower in individuals with TT genotype than in those with the Tt and tt genotypes (X2=21.9; P=0.006). Furthermore a significant association was found between 713-8delC and bone turnover. The results suggest a strong evidence for an association among the 713-8delC allele of the TGF-beta1 gene and the femoral BMD, the prevalence of osteoporotic fractures, and finally a high bone turnover in a sample of Italian postmenopausal women.

A histomorphometric long-term longitudinal study of trabecular bone loss in glucocorticoid-treated patients: prednisone versus deflazacort.

Administration of a corticosteroid with minor osteopenic effects is considered an effective prevention of glucocorticoid osteoporosis. Deflazacort, an oxazolinic derivative of prednisolone, is reported to be less harmful to cancellous bone mass than other equally effective corticosteroids. However, comparative long-term studies, particularly on trabecular bone, are needed before a smaller detrimental effect on bone of deflazacort can be unequivocally confirmed. We conducted such a prospective long-term study using histomorphometric analysis of iliac bone. For the study, 18 pairs of nonimmobilized patients, matched for age, sex, menopausal state, corticosteroid dose, and type and severity of the disease, were randomly submitted to treatment with therapeutically equivalent doses of prednisone or deflazacort. Bone biopsies from iliac crest were taken before and at various times during treatment. In order to represent the time-related trabecular bone loss and find out possible differences between patients on prednisone or deflazacort, a previously described model of bone loss kinetics was applied. No significant differences in biochemical indices of bone turnover or in histomorphometric variables between prednisone- and deflazacort-treated patients were recorded before treatment. The mean duration of treatment at the final biopsy was similar for prednisone and deflazacort (15.8 and 15.2 months, respectively). Patients showed evident clinical improvement with both treatments. Osteoid and resorption surfaces showed no significant differences throughout the observation period in any of the 18 pairs. On the contrary, both steroids induced a significant decrease in trabecular bone, although the bone loss rate induced by prednisone was significantly higher than that induced by deflazacort (P < 0.05). The kinetics of bone loss and the different osteopenic effects of the two drugs are described by the negative exponential function fitted to data from patients never previously given glucocorticoids; the model yields highly significant difference (P approximately equal to 0.01) between the two drugs and allows estimation of the difference even 3 years after the beginning of treatment (-3.0%/year versus -1.1%/year for prednisone and deflazacort, respectively). This prospective long-term study confirms that an exponential model accurately describes the trabecular bone loss induced by long-term corticosteroid treatment and demonstrates that deflazacort, at therapeutically effective doses, induces less trabecular bone loss than prednisone.

Effect of bisphosphonate therapy and parathyroidectomy on the urinary excretion of galactosylhydroxylysine in primary hyperparathyroidism.

BACKGROUND: In patients with mild or asymptomatic primary hyperparathyroidism a reliable index of bone resorption might be useful for appropriate management. Hydroxyproline is the most commonly used marker of bone resorption but its low specificity and sensitivity are known. Galactosylhydroxylysine, an amino acid mainly represented in bone collagen, has been proposed as a more suitable index of bone resorption. In this study we evaluated the sensitivity of galactosylhydroxylysine and hydroxyproline assays in following the changes of their urinary levels in 12 patients with mild primary hyperparathyroidism before and after treatment with bisphosphonate and surgery. METHODS: Serum and fasting urine specimens were obtained from 12 women with mild primary hyperparathyroidism before and after bisphosphonate treatment (2.5 mg daily for 5 days, intravenously) and after a further 25 days; in 7 patients biochemical tests were also performed 1 and 6 days after parathyroidectomy. Galactosylhydroxylysine was assayed by an HPLC method and hydroxyproline by a RIA commercial kit. RESULTS: Baseline galactosylhydroxylysine urinary levels were far above the normal range in all the patients whilst in 8 of them baseline hydroxyproline levels were normal. Bisphosphonate treatment significantly decreased bone turnover as shown by a significant fall in serum calcium (from 2.9 to 2.6 mmol/l; P < 0.001) and in galactosylhydroxylysine and hydroxyproline (-55 and -31% respectively). Twenty-five days after the end of treatment, resorption increased again and serum calcium and galactosylhydroxylysine, but not hydroxyproline, rose significantly towards basal levels. One day after parathyroidectomy serum calcium, galactosylhydroxylysine and PTH showed reduction below normal ranges. PTH and galactosylhydroxylysine returned to normal values at day 6 after parathyroidectomy. No changes in hydroxyproline levels were seen. Galactosylhydroxylysine, but not hydroxyproline, correlated significantly with serum calcium and PTH. CONCLUSION: Galactosylhydroxylysine appears to be a sensitive index of bone resorption, useful in the clinical assessment of bone involvement and in the management of patients with mild primary hyperparathyroidism.

Duration of the effects of intravenous alendronate in postmenopausal women and in patients with primary hyperparathyroidism and Paget's disease of bone.

The effect of a single intravenous (i.v.) infusion of 5 mg alendronate was studied in ten patients with Paget's disease, six patients with primary hyperparathyroidism and ten osteopenic postmenopausal women. Urinary hydroxyproline excretion significantly decreased within few days in all patients (from 113 +/- 67.9 to 58 +/- 35 mmol/mol Cr in Paget's disease, from 21.8 +/- 9 to 12.9 +/- 6 mmol/mol Cr in hyperparathyroidism, from 18.7 +/- 9.5 to 8.5 +/- 4.3 mmol/mol Cr in postmenopausal women). In the patients with Paget's disease urinary hydroxyproline remained suppressed over the 6 months of follow-up, whereas it rose toward pretreatment values within 4 and 6 weeks in the patients with primary hyperparathyroidism and in postmenopausal osteopenic women, respectively. Plasma alkaline phosphatase significantly fell only after 4-6 weeks in patients with primary hyperparathyroidism and in Pagetic patients. In the latter group alkaline phosphatase continued to decline thereafter and a plateau became apparent after 2 months. In postmenopausal women the serum alkaline phosphatase remained unchanged. Thus, the same dose of alendronate induces comparable fractional decreases of bone resorption in the three groups of patients, but the effect is persistent only in Paget's disease. This is consistent with the hypothesis that alendronate inhibits osteoclastic activity only at the level of the existing resorption sites. In osteoporotic and primary hyperparathyroid patients, as soon as the treatment is withdrawn, the appearance of new sites of resorption is not inhibited and bone turnover is resumed to pre-treatment values.(ABSTRACT TRUNCATED AT 250 WORDS)

Effect of deflazacort on growth hormone response to insulin tolerance test.

Deflazacort (DF) has been claimed to be provided with a reduced distribution into the central nervous system, therefore it is conceivable that this glucocorticoid holds a lower inhibitory effect on GH secretion. To test this hypothesis we studied the GH response to insulin tolerance test (ITT) in two matched groups of patients given equivalent doses of DF and prednisone (PN). The serum glucose changes induced by ITT were similar in the two groups and in control subjects; the mean increase in plasma GH, in particular the peak and the area under the curve (delta AUC), were not different in control subjects and DF-treated patients (25 +/- 12.5 ng/ml and 1790 +/- 904 ng/ml/min versus 27.7 +/- 21.5 ng/ml and 1578 +/- 1242 ng/ml/min) but were significantly reduced in PN-treated patients (8.8 +/- 9.7 ng/ml and 431.6 +/- 451 ng/ml/min). Our study demonstrates that DF does not interfere with the GH response to ITT as PN does.

Bone loss in response to long-term glucocorticoid therapy.

A number of studies have shown that an excess of glucocorticoids induces osteoporosis, but the mechanism(s) and the time course of the reduction of bone mass remain uncertain. In order to clarify this issue we carried out a longitudinal clinical and histomorphometric study of patients requiring long-term glucocorticoid treatment. In 23 patients (9 men, 10 post- and 4 premenopausal women) biochemical and bone histomorphometric investigations were carried out before and during treatment with 10-25 mg/day of prednisone. Histomorphometric analysis of bone biopsies of the iliac crest showed that the decrease of TBV (up to -27%, P less than 0.001) occurs predominantly within the first 5-7 months of treatment; during the subsequent stages, which include observations after 12 months of treatment, only minor changes were observed. Therefore trabecular bone loss can be satisfactorily described by a negative exponential function. None of the other histomorphometric parameters (osteoid surfaces, resorption surfaces, etc.) showed significant changes. However, the histological features of the bone biopsies during steroid therapy, showing a virtual lack of osteoblastic activity, ruled out an increase of bone resorption. Moreover, the dynamic study of the bone formation by double tetracycline labelling showed, in a small subgroup of patients, a decrease of the apposition rates (from 0.763 +/- 0.053 to 0.305 +/- 0.074 microns/day (mean +/- SE) after treatment). No significant changes, at any time during steroid treatment, were observed in serum alkaline phosphatase, 25-hydroxyvitamin D, 24,25-dihydroxyvitamin D, 1,25-dihydroxyvitamin D, parathyroid hormone or urinary calcium excretion. Serum calcium increased significantly within the first 1-2 months of therapy and then it returned to baseline. Urinary hydroxyproline excretion decreased significantly within the first 1-2 months and continued to fall throughout the treatment. Thus, both biochemical and histological findings suggest that long-term glucocorticoid therapy causes a reduction of bone turnover, that the bone loss occurs predominantly within the first 6 months of treatment and that patients with lower bone mass have a lower rate of bone loss.

Intramuscular administration of salmon calcitonin impairs delayed cutaneous hypersensitivity.

The delayed cutaneous hypersensitivity to seven ubiquitous antigens (Multitest CMI, Istitute Merieux) was evaluated in normal healthy volunteers before and at the time of intramuscular administration of 50 (12 subjects) or 50 + 50 (nine subjects) units of salmon calcitonin or 2 ml of saline (eight subjects). The delayed cutaneous hypersensitivity, in terms of number of positive tests or sum of positive tests, significantly fell in both groups given salmon calcitonin, but no changes were observed in the control group. These results indicate that salmon calcitonin, as well as inhibiting osteoclastic bone resorption, has important immunological effects.

Substrate-product relation of 1-hydroxylase activity in primary hyperparathyroidism.

The synthesis of the active form of vitamin D, 1,25-dihydroxyvitamin D (1,25-(OH)2D), is thought to be relatively insensitive to the serum concentration of its precursor, 25-hydroxyvitamin D (25-OH-D). We compared the effect of oral administration of 25-OH-D3 (50 micrograms per day for one month) on serum concentrations of calcium, phosphate, parathyroid hormone, 25-OH-D, and 1,25-(OH)2D in five healthy adults and in six patients with primary hyperparathyroidism. In normal adults the mean (+/- S.D.) serum level of 25-OH-D rose from 18 +/- 9 to 136 +/- 47 ng per milliliter; no significant changes were observed in the other serum levels. In contrast, comparable increases in the levels of circulating 25-OH-D in patients with primary hyperparathyroidism caused a consistent slight rise in serum calcium and phosphate levels, a partial suppression of parathyroid hormone, and a sharp increase in the level of 1,25-(OH)2D. During this period a significant positive correlation was found between serum concentrations of 25-OH-D and 1,25-(OH)2D (P less than 0.001). These results provide evidence that in patients with primary hyperparathyroidism, levels of circulating 1,25-(OH)2D may be more dependent on the prevailing serum concentrations of 25-OH-D than they are in normal adults.

Effect of exogenous gastrointestinal peptides containing the C-terminal tetrapeptide of gastrin on calcium, calcitonin and parathormone serum levels in man.

Gastrointestinal hormones containing the C-terminal tetrapeptide of gastrin are involved in calcium homeostasis. The aim of this study was to investigate: 1) the effect of a standard meal (schedule a) and of a duodenal infusion of 5% aminoacid solution (schedule b) on calcium, CT and PTH serum levels in man; 2) the behaviour of these parameters during I.V. infusions of pentagastrin (mcg 1.5/Kg-hour), sincalide (mcg 0.04/Kg-hour) and caerulein (ng 75/Kg-hour) (schedule c). In order to avoid any possible interference by endogenous secretin release, schedule c was performed in 5 patients previously submitted to total gastrectomy. Schedule a and b were studied in 5 healthy volunteers. After a standard meal a slight increase of CT and PTH was measured. Duodenal infusion of aminoacid was followed by hypocalcaemia and slight but constant rise of CT levels, without significant variations of circulating PTH. Pentagastrin, sincalide and caerulein induced a slight but significant hypocalcaemia and a rise of serum CT levels, together with a significant increase of serum PTH. These findings suggest that peptides containing the C-terminal tetrapeptide of gastrin directly affect calcium homeostasis in the absence of secretin release.