Dynamic investigation for evaluation of calcium metabolism and parathyroid function

Differently from other metabolic conditions, most of calcium metabolism disorders are diagnosed through simple detection of both serum and urinary excretion (24-h urine collection), levels of calcium, total and ionized form, and phosphate, and of calciotropic hormone serum levels, such as calcitonin, PTH and vitamin D metabolites. For the diagnosis and clinical monitoring of some metabolic bone diseases, such as osteoporosis and Paget's disease, the assessment of bone turnover is offering a useful tool for the evaluation of the therapeutic response in affected individuals. Markers of bone formation are represented by bone alkaline phosphatase and osteocalcin, while principal bone resorption markers are represented by pyridinoline, deoxypyridinoline and crosslinks of collagen N-telopeptide, both in the 24-h and fasting second morning urine collection. Only in selected conditions, here briefly reviewed, dynamic tests can offer an interpretation on the pathogenetic events causing a disorder of calcium metabolism.

Cytocompatibility of polyurethane foams as biointegrable matrices for the preparation of scaffolds for bone reconstruction

This work reports preliminary results on the development of biointegrable scaffolds, composed of biostable 3D polymer matrices and bioabsorbable inorganic salts, to be used for cell anchorage in bone regeneration. Three crosslinked polyurethane foams (PUFs), prepared by one-step bulk polymerisation from a polyether-polyol mixture, polymeric MDI and water as expanding agent, were tested for their ability to promote adhesion and growth of bone-derived cells. The open porosity of these foams ranged from 16 to 31% with an average pore size of 470 /600 microm, compressive strength (at 10% ε ) of 0.28/0.38 MPa and elastic moduli of 4.88/6.61 MPa. The human osteosarcoma line Saos-2, and primary cultures of normal human articular chondrocytes and bone marrow-derived (HBM) stromal cells were used for in vitro cytocompatibility tests. For cell adhesion and proliferation analysis, DNA synthesis was evaluated by 3 H-thymidine uptake. Osteoblastic differentiation of Saos-2 adherent cells was determined by measuring the enzymatic activity of alkaline phosphatase (ALP). All cell types were able to adhere to all tested PUFs and to synthesize DNA. At 48 hr culture, HBM stromal cells showed the maximal rate of adhesion with the highest rate of proliferation onto PUFs with the largest pore size, whereas both chondrocytes and Saos-2 appeared to adhere preferentially onto foams exhibiting the highest percentage of open porosity. Up to 8 days in culture Saos-2 cells were able to proliferate into all PUFs, with a time-dependent increase of DNA synthesis and ALP activity. At SEM, the morphology of cells adherent to PUF pores was spread with cytoplasmatic extroflessions, indicating a good metabolic activation. These results demonstrate a good cytocompatibility of the proposed 3D matrices, suggesting that their use in the preparation of composite scaffolds is worth further investigation. (Journal of Applied Biomaterials & Biomechanics 2003; 1: 58-66)ABSTRACT: This work reports preliminary results on the development of biointegrable scaffolds, composed of biostable 3D polymer matrices and bioabsorbable inorganic salts, to be used for cell anchorage in bone regeneration. Three crosslinked polyurethane foams (PUFs), prepared by one-step bulk polymerisation from a polyether-polyol mixture, polymeric MDI and water as expanding agent, were tested for their ability to promote adhesion and growth of bone-derived cells. The open porosity of these foams ranged from 16 to 31% with an average pore size of 470 /600 microm, compressive strength (at 10% ε ) of 0.28/0.38 MPa and elastic moduli of 4.88/6.61 MPa. The human osteosarcoma line Saos-2, and primary cultures of normal human articular chondrocytes and bone marrow-derived (HBM) stromal cells were used for in vitro cytocompatibility tests. For cell adhesion and proliferation analysis, DNA synthesis was evaluated by 3 H-thymidine uptake. Osteoblastic differentiation of Saos-2 adherent cells was determined by measuring the enzymatic activity of alkaline phosphatase (ALP). All cell types were able to adhere to all tested PUFs and to synthesize DNA. At 48 hr culture, HBM stromal cells showed the maximal rate of adhesion with the highest rate of proliferation onto PUFs with the largest pore size, whereas both chondrocytes and Saos-2 appeared to adhere preferentially onto foams exhibiting the highest percentage of open porosity. Up to 8 days in culture Saos-2 cells were able to proliferate into all PUFs, with a time-dependent increase of DNA synthesis and ALP activity. At SEM, the morphology of cells adherent to PUF pores was spread with cytoplasmatic extroflessions, indicating a good metabolic activation. These results demonstrate a good cytocompatibility of the proposed 3D matrices, suggesting that their use in the preparation of composite scaffolds is worth further investigation. (Journal of Applied Biomaterials & Biomechanics 2003; 1: 58-66).

Dose-dependent inhibition of mitochondrial ATP synthase by 17 beta-estradiol

Mitochondria produce energy through oxidative phosphorylation. A key enzyme in this pathway is F0F1-ATP synthase, catalyzing ATP production from ADP and inorganic phosphate. Recently a subunit of F0F1-ATP synthase, oligomycin sensitivity-conferring protein, was identified as a new estradiol-binding protein. Estradiol could directly modulate mitochondrial ATP synthase activity through this subunit. In addition, intracellular ATP levels play a role in apoptotic death, which is an energy-dependent process requiring functioning mitochondria. Here we examined the effect of 17 beta-estradiol on F0F1-ATP synthase directly (in permeabilized cells) and in intact osteoclastic FLG 29.1 cells, a model of inducible apoptosis. The baseline F0F1-ATP synthase activity of FLG 29.1 cells was 4.485 nmol/min per mg. Estradiol rapidly inhibited F0F1-ATP synthase activity in the physiological range (half-inhibition concentration, IC50, of 30 nmol/l). With 1 nmol/l of estradiol, the inhibition was already significant (8-10% inhibition, p < 0.01) and with 100 nmol/l residual enzyme activity was only 15% (85% inhibition, p < 0.01). In addition, the effect of estradiol appeared to be directed towards F0F1-ATP synthase, since succinate-sustained respiration, uncoupled from the electron transport chain, was unaffected by estradiol. We assayed F0F1-ATP synthase activity in FLG 29.1 cells during inducible apoptosis. No significant difference of ATP synthesis was detected in apoptotic cells versus controls. In conclusion, we showed a new non-genomic effect of estradiol on a key mitochondrial enzyme, which thereby directly modulates cellular energy metabolism.

Estrogen metabolism in human colorectal cancer cells

Epidemiological and "in vitro" studies support a direct role of estrogens in the pathogenesis and/or progression of colorectal cancer (CRC). Recent observations suggest a local synthesis of 17beta-estradiol (E(2)). In the present study, the CRC estrogen receptor beta (ERbeta) positive HCT8, HCT116, DLD-1 and LoVo cell lines were evaluated for expression of functional 17beta-hydroxysteroid dehydrogenase (17betaHSD) types 1, 2, 3, and 4. RT-PCR analysis revealed that while 17betaHSD1 and 17betaHSD4 were expressed in all the four cell lines, 17betaHSD2 and 17betaHSD3 were expressed in a cell-specific manner. The interconversion of tritiated estrone (E(1)) or E(2) evaluated by thin layer chromatography of conditioned media revealed that in HCT8, HCT116, and DLD-1 cells both reductive and oxidative activities were present, the latter showing K(m) values (approximately 10 microM) 40-fold higher than the former (approximately 250 nM). On the contrary, in LoVo cells, estrogens were almost (approximately 90%) completely metabolized to hydrophile compounds. Charcoal-dextrane (DC) stripped fetal calf serum (FCS) (10%), E(2) (10nM), Vitamin D(3) (100nM) and the combined E(2) and Vitamin D(3) treatment were evaluated for modulation of 17betaHSD isoenzymes gene expression and activity. Gene expression and activity of 17betaHSD reductive and oxidative isoenzymes were respectively inhibited and enhanced by Vitamin D(3) in HCT8 and LoVo cells. Surprisingly, DC-FCS induced a marked increase of estrogen metabolism toward hydrophile metabolites in all four cell lines. In conclusion, our results clearly show that metabolism of estrogens by 17betaHSD isoenzymes is functional and modulated by external stimuli in continuous neoplastic colonic epithelial cell lines.

Strontium ranelate: dose-dependent effects in established postmenopausal vertebral osteoporosis--a 2-year randomized placebo controlled trial

The aim of the strontium ranelate (SR) for treatment of osteoporosis (STRATOS) trial was to investigate the efficacy and safety of different doses of SR, a novel agent in the treatment of postmenopausal osteoporosis. A randomized, multicenter, double-blind, placebo-controlled trial was undertaken in 353 osteoporotic women with at least one previous vertebral fracture and a lumbar T-score <-2.4. Patients were randomized to receive placebo, 0.5 g, 1 g, or 2 g SR/d for 2 yr. The primary efficacy endpoint was lumbar bone mineral density (BMD), assessed by dual-energy x-ray absorptiometry. Secondary outcome measures included femoral BMD, incidence of new vertebral deformities, and biochemical markers of bone metabolism. Lumbar BMD, adjusted for bone strontium content, increased in a dose-dependent manner in the intention-to-treat population: mean annual slope increased from 1.4% with 0.5 g/d SR to 3.0% with 2 g/d SR, which was significantly higher than placebo (P < 0.01). There was a significant reduction in the number of patients experiencing new vertebral deformities in the second year of treatment with 2 g/d SR [relative risk 0.56; 95% confidence interval (0.35; 0.89)]. In the 2 g/d group, there was a significant increase in serum levels of bone alkaline phosphatase, whereas urinary excretion of cross-linked N-telopeptide, a marker of bone resorption, was lower with SR than with placebo. All tested doses were well tolerated; the 2 g/d dose was considered to offer the best combination of efficacy and safety. In conclusion, SR therapy increased vertebral BMD and reduced the incidence of vertebral fractures.

Genetics of osteoporosis: role of steroid hormone receptor gene polymorphisms

Osteoporosis is a common skeletal disease characterized by low bone mass and microarchitectural deterioration of bone tissue with a consequent increase in bone fragility and susceptibility to fracture. In the past years, twin and family study have shown that this disease recognizes a strong genetic component and that genetic factors play an important role in regulating bone mineral density (BMD). While in few isolate conditions osteoporosis can be inherited in a simple Mendelian pattern, due to single gene mutations, in the majority of cases has to be considered a multifactorial polygenic disease in which genetic determinants are modulated by hormonal, environmental and nutritional factors. Given the important role that steroid hormones play in bone cell development and in the maintenance of normal bone architecture, polymorphisms at receptor of the steroid/thyroid hormone receptor superfamily, such as estrogen receptor alpha (ERalpha) and Vitamin D receptor (VDR) have been thoroughly investigated in the last years and appeared to represent important candidate genes. The individual contribution of these genetic polymorphisms to the pathogenesis of osteoporosis remains to be universally confirmed and an important aim in future work will be to define their functional molecular consequences and how these polymorphisms interact with each other and with the environment to cause the osteoporotic phenotype. A further promising application of genetic studies in osteoporosis comes from their pharmacogenomic implications, with the possibility to give a better guidance for therapeutic agents commonly used to treat this invalidating disorder or to identify target molecules for new therapeutic agents.

Guidelines for diagnosis and therapy of MEN type 1 and type 2

This is a consensus statement from an international group, mostly of clinical endocrinologists. MEN1 and MEN2 are hereditary cancer syndromes. The commonest tumors secrete PTH or gastrin in MEN1, and calcitonin or catecholamines in MEN2. Management strategies improved after the discoveries of their genes. MEN1 has no clear syndromic variants. Tumor monitoring in MEN1 carriers includes biochemical tests yearly and imaging tests less often. Neck surgery includes subtotal or total parathyroidectomy, parathyroid cryopreservation, and thymectomy. Proton pump inhibitors or somatostatin analogs are the main management for oversecretion of entero-pancreatic hormones, except insulin. The roles for surgery of most entero-pancreatic tumors present several controversies: exclusion of most operations on gastrinomas and indications for surgery on other tumors. Each MEN1 family probably has an inactivating MEN1 germline mutation. Testing for a germline MEN1 mutation gives useful information, but rarely mandates an intervention. The most distinctive MEN2 variants are MEN2A, MEN2B, and familial medullary thyroid cancer (MTC). They vary in aggressiveness of MTC and spectrum of disturbed organs. Mortality in MEN2 is greater from MTC than from pheochromocytoma. Thyroidectomy, during childhood if possible, is the goal in all MEN2 carriers to prevent or cure MTC. Each MEN2 index case probably has an activating germline RET mutation. RET testing has replaced calcitonin testing to diagnose the MEN2 carrier state. The specific RET codon mutation correlates with the MEN2 syndromic variant, the age of onset of MTC, and the aggressiveness of MTC; consequently, that mutation should guide major management decisions, such as whether and when to perform thyroidectomy.

Genetics of menopause-associated diseases

Menopause is the permanent cessation of menstruation resulting from the loss of ovarian follicular activity. It is estimated that perhaps 50 million women worldwide will go into menopause annually. Atherosclerotic cardiovascular disease, osteoporotic fractures and Alzheimer's dementia are common chronic disorders after menopause, representing major health problems in most developed countries. Apart from being influenced by environmental factors, these chronic disorders recognize a strong genetic component, and there are now considerable clinic evidences that these disorders are related to low hormonal milieu of postmenopausal women. Here, we review up-to-date available data suggesting that genetic variation may contribute to higher susceptibility to four sporadic chronic syndromes such as osteoporosis (OP), osteoarthritis (OA), Alzheimer's disease (AD) and coronary artery disease (CAD). For these four syndromes candidate genes that today appear as major loci in genetic susceptibility encode for proteins specific of a given system, as the vitamin D receptor (VDR) gene for the skeleton and, therefore, OP or angiotensin converting enzyme (ACE) for the cardiovascular system and, therefore, CAD. The investigation of gene polymorphisms in various pathological conditions typical of postmenopause offer an explanation not only of their genetic inheritance but also of their co-segregation in given individuals. In this view, it may be possible to identify a common set of genes whose variants contribute to a common genetic background for these different disorders. Ideal candidates appear genes of the estrogen response cascade [i.e. estrogen receptor (ERs), enzymes involved in estrogen metabolism or co-activators and co-inhibitors]. All together this information may represent the basis both for future recognition of individuals at risk and for the pharmacogenetic driving of drug responsiveness.

Genetics of male osteoporosis

In the past years, several epidemiological and clinical observations have underlined the importance of genetics in the pathogenesis of both female and male osteoporosis. It has been estimated that from 50 to 80% of the inter-individual variability in bone mass is genetically determined. In rare instances, osteoporosis in men could be inherited in a simple Mendelian pattern. Examples of this include familial osteoporotic syndromes due to mutations in the aromatase and ER alpha genes. Families have also been described in which high bone mass is inherited as an autosomal dominant trait, consistent with the effect of a single gene located on chromosome 11. However, except for these rare conditions, osteoporosis has to be considered a multifactorial disease in which genetic determinants are modulated by hormonal, environmental, and nutritional factors. The genetic effect on bone may also be gender- and site-specific, with different genes regulating bone density at different skeletal sites in males and females. To date, most of the work on the genetics of osteoporosis has focused on women. In some studies, polymorphisms at the IGF-I, VDR, COLI-alpha1, ER alpha, and aromatase gene have been recently shown to predict BMD variation and osteoporotic risk in males. These observations remain to be confirmed by other independent studies. Other candidate genes, are still awaiting mapping and identification.

[Use of clodronic acid in mineral metabolism conditions: state of the art in 2000]

Clodronic acid is a non-aminate bisphosphonate capable of inhibiting bone resorption. Pharmacological and clinical trials have shown the efficacy of clodronic acid in the treatment of post-menopausal osteoporosis and in all conditions of excess bone resorption, such as Paget's disease, malignant tumoral hypercalcemia and osteolytic metastases. Clodronic acid is the only bisphosphonate currently on the market available for both oral and parenteral administration. Intramuscular therapy with clodronic acid at a dose of 100 mg/week has shown significant effects on bone mineral density after 6 months treatment in patients with postmenopausal osteoporosis and these effects were maintained 3 years after the start of treatment. Increased bone mass is associated with a reduced risk of the onset of vertebral fractures. In a recent three-year study a significant increase was observed in bone mineral density associated with a 46% reduction in the incidence of vertebral fractures. The reduction in bone pain after parenteral treatment with clodronic acid is an important added value in the use of this molecule in osteopenic pathologies. Moreover the costs of parenteral clodronic acid treatment is certainly competitive compared to other drugs. Oral and parenteral clodronic acid was well tolerated in clinical trials. Gastrointestinal adverse effects were described only with high oral doses. These effects were transient and generally resolved without interrupting the treatment. Clodronic acid is an effective and well tolerated drug able to inhibit bone resorption. The low incidence of undesired effects at a gastroenteric level, the possibility of formulas for parenteral administration, the antalgic effect and low costs make clodronic acid an extremely interesting molecule for the prevention and treatment of postmenopausal osteoporosis and all conditions of excessive bone resorption, such as Paget's disease, malignant tumoral hypercalcemia, osteolytic metastasis and hyperparathyroidism.

TGF-beta isoform and receptor expression in giant cell tumor and giant cell lesions of bone

The authors examined the distribution of tumor growth factor-beta (TGF-beta) isoforms and receptors in 35 giant cell tumor (GCT) of bone in comparison with a group of benign giant cell-containing lesions of bone, including 5 aneurysmal bone cysts, 2 cases of brown tumor of hyperparathyroidism, 3 nonossifying fibromas, and 7 cases of giant cell reparative granuloma. The results of immunohistochemical analysis of GCT showed a complete absence of TGF-beta1 expression in both mononuclear tumor cells and giant cells. Only reactive bone present within the tumor showed an intense immunoreactivity. Transforming growth factor-beta2 and TGF-beta3 were detected in the majority of cases (97.1% and 82.8%, respectively), whereas TGF-beta receptor type I (TGF-beta RI) and type II (TGF-beta RII) were diffusely expressed in all cases. Reverse transcription-polymerase chain reaction (RT-PCR) analysis performed on 10 GCTs with specific oligonucleotide primers demonstrated the presence of mRNA transcripts for TGF-beta1, 2, 3, and for TGF-beta RI and RII. Quantitative measurements of TGF-beta1 in conditioned media from primary cultures of GCT showed undetectable or very low amounts of the cytokine (0-23 pg/mL). The results of immunohistochemical analysis showed that all giant cell-containing lesions of bone were at least focally positive for the 3 isoform of TGF-beta, with positivity present both in osteoclast-like giant cells and mononuclear cells, and diffusely positive for TGF-beta RI and RII. Reverse transcription-polymerase chain reaction analysis conducted on samples from 3 nonossifying fibromas and 1 giant cell reparative granuloma confirmed the expression of the corresponding mRNA. In conclusion, according to the current data, GCT of bone can be distinguished from other giant cell-containing lesions of bone on the basis of the absence of TGF-beta1 expression at the protein level, which appears to be the result of posttranslational regulation processes.

Polymorphism of the aromatase gene in postmenopausal Italian women: distribution and correlation with bone mass and fracture risk

Conversion of C(19) steroids to estrogens is catalyzed by the aromatase enzyme. Inactivating mutations of the aromatase gene are associated with decreased bone mineral density in both men and women. Genetic studies suggest that several genes contribute to the regulation of bone mass via interaction with the modeling and remodeling processes. Among these genes, the aromatase gene is a potential candidate to be evaluated for segregation with bone metabolism and bone mass. A tetranucleotide simple tandem repeat polymorphism in intron 4 at the human aromatase cytochrome P-450 gene has been recently described. In the present study we evaluated the distribution of this polymorphism in a cohort of Italian postmenopausal women, both normal and osteoporotic. We observed that the NN genotype was significantly more frequent in nonosteoporotic women than in osteoporotic women (72.7% vs. 27.2%), whereas the DN genotype was significantly more represented in osteoporotic women (90.48% vs. 9.5%; Pearson's chi(2) test = 42.8; df = 10; P = or < 0.01). The allele containing the longer TTTA repeats was statistically more represented in nonosteoporotic women (Pearson's chi(2) test = 19.14; df = 2; P = 0.00007). In addition, women with a high number of TTTA repeats had a significantly higher lumbar bone mineral density than women with alleles containing 8-11 TTTA repeats (P = 0.03). Finally, considering the spine fractures, a significantly higher incidence was observed in women with shorter TTTA repeats than in those with longer TTTA repeats (Pearson's chi(2) test = 7.3; df = 2; P = 0.02), equivalent to a relative risk of 4.1 (95% confidence interval, 1.19-13.87). In conclusion, the aromatase gene can be one of the several genes potentially involved in the maintenance of bone mass and in the regulation of bone mass loss.

The importance of the unsuppressed glands in the study of intact parathyroid hormone disappearance after parathyroid adenomectomy

BACKGROUND

In the usual techniques for intraoperative intact parathyroid hormone (iPTH) monitoring for primary hyperparathyroidism, the normal glands are implicitly considered suppressed. On the contrary, we believe, as do other researchers, that they are not totally suppressed.

METHODS

For this reason, we considered the introduction of an infusion from the unsuppressed normal glands (UNG), described by an influx constant (IC (pg/ml per min)), into the formulation of a two-compartment model. For the blood compartment, we have: C(t)=A.exp(-at)+B.exp(-bt)+EV, where A+B+EV=iPTH concentration at zero time (clamping), EV (equilibrium value)=IC/k, 'a' and 'b' are reciprocals of the time constants of the two exponentials and k=rate constant of elimination from the blood. The experimental data were obtained using an IRMA standard method, collecting samples in 20 patients, during and following adenomectomy.

RESULTS

In spite of the variability among the patients, all fits were very good, thus confirming the importance of the UNG contribution to the shaping of the disappearance curve. For this reason, the relationship between the constant infusion from the UNG and the basal iPTH level at the induction of anaesthesia (BV), was studied.

CONCLUSIONS

The existence of a negative correlation, together with the determination of a regression curve (IC=6.5BV), not only confirmed our assumptions, but also revealed the theoretical possibility of a priori knowledge of the iPTH contribution from the UNG. Hence, there is a theoretical possibility of discriminating between this contribution and that of the remaining (if any) affected gland(s).

Microencapsulation of human parathyroid cells: an "in vitro" study

BACKGROUND

Patients affected by hypoparathyroidism of variable etiology are currently treated with exogenously administered vitamin D and calcium. Human parathyroid transplantation has long been investigated as a possible mean of treating these patients to prevent long-term hypocalcemia. However, the main obstacle for this treatment is represented by tissue rejection. A reliable method to efficiently protect the transplanted tissue from rejection and to allow long-term survival of the graft is the encapsulation of tissues or cells in alginate-polylysine-alginate membranes, which were successfully used for encapsulation of islets of Langerhans. The microencapsulation of parathyroid tissue fragments or of parathyroid cells becomes, therefore, a potential approach for the successful treatment of permanent symptomatic hypoparathyroidism without pharmacological immunosuppression.

MATERIALS AND METHODS

We describe microencapsulation of differentiated human parathyroid cells derived from adenoma or hyperplastic glands. Long-term viability, cell growth, and parathyroid hormone production of microencapsulated cells were evaluated together with responsiveness to extracellular Ca(2+).

RESULTS

Microencapsulated parathyroid cells maintained proliferative and differentiative properties for a long term in culture with a good response to extracellular Ca(2+) concentration.

CONCLUSIONS

These findings represent a crucial step toward the construction of functional bioartificial parathyroid organoids for the treatment of hypoparathyroidism in humans.

Genotype distribution of estrogen receptor-alpha gene polymorphisms in Italian women with surgical uterine leiomyomas

OBJECTIVE

To explore a possible association between estrogen receptor-alpha (ER-alpha) gene polymorphisms and development of uterine leiomyomas.

DESIGN

Case-control study.

SETTING

University teaching hospital.

PATIENT(S)

119 women with clinically and surgically diagnosed uterine leiomyomas.

INTERVENTION(S)

Therapeutic hysterectomy.

MAIN OUTCOME MEASURE(S)

Frequency and distribution of ER-alpha gene polymorphisms.

RESULT(S)

No statistically significant differences between controls and patients in the allele frequency and genotype distribution were found when Pvu II and Xba I restriction polymorphism sites were analyzed separately. When the two ER-alpha gene polymorphisms were analyzed in combination, five major genotypes were recognized in controls or patients; the frequency differed slightly but not significantly between groups.

CONCLUSION(S)

The Pvu II and Xba I polymorphisms in the ER-alpha gene do not produce different risks of developing uterine leiomyomas.

Physiopathological basis of bone turnover

Bone remodeling involves the continuous removal of bone (bone resorption) followed by synthesis of new bone matrix and subsequent mineralization (bone formation). The principal cells that mediate the boneforming processes of the skeleton are osteoblast cells. They are responsible for the production of the matrix constituents and the differentiation of osteoblasts from stromal cell precursors is stimulated by several hormonal and non-hormonal molecules. On the other hand, the osteoclasts are giant multinucleated cells responsible of bone resorption. They are formed in the bone marrow and mature cells are stimulated by PTH and locally acting agents such as transforming growth factor alpha (TGFalpha), tumor necrosis factor (TNF) interleukin 1 (IL-1) and interleukin 6 (IL-6). The first events during bone remodeling is osteoclast activation, followed by osteoclast formation, polarization constitution of the ruffled border, resorption and ultimately apoptosis. Osteoclast apoptosis is followed by a series of sequential changes in cells in the osteoblast lineage, including osteoblast chemotaxis, proliferation and differentiation, which in turn is followed by formation of mineralized bone and cessation of osteoblast activity. The final phase of the formation process is cessation of osteoblast activity. The resorption lacunae are usually repaired either completely or almost completely. Understanding the sequence of cellular events may be important to better know the mechanisms responsible for bone loss that occurs in age and in several pathological conditions.

Genetic markers of osteoarticular disorders: facts and hopes

Osteoarthritis and osteoporosis are the two most common age-related chronic disorders of articular joints and skeleton, representing a major public health problem in most developed countries. Apart from being influenced by environmental factors, both disorders have a strong genetic component, and there is now considerable evidence from large population studies that these two disorders are inversely related. Thus, an accurate analysis of the genetic component of one of these two multifactorial diseases may provide data of interest for the other. However, the existence of confounding factors must always be borne in mind in interpreting the genetic analysis. In addition, each patient must be given an accurate clinical evaluation, including family history, history of drug treatments, lifestyle, and environment, in order to reduce the background bias. Here, we review the impact of recent work in molecular genetics suggesting that powerful molecular biology techniques will soon make possible both a rapid accumulation of data on the genetics of both disorders and the development of novel diagnostic, prognostic, and therapeutic approaches.

Modulation of the effects of osteoprotegerin (OPG) ligand in a human leukemic cell line by OPG and calcitonin

The discovery of osteoprotegerin (OPG), osteoprotegerin ligand (OPGL), and RANK has elucidated the mechanism by which osteoblasts and stromal cells regulate osteoclastic differentiation and function and mediate the effects exerted by other hormones and cytokines. We have investigated the effects of these novel cytokines on the preosteoclastic cell line FLG 29.1. We show that OPGL alone and in combination with macrophage colony-stimulating factor (CSF-1) dramatically reduced replication and increased tartrate-resistant acid phosphatase activity. However, although FLG29.1 cells appear to adhere to the bone surface, they are not able to form resorption lacunae. OPG and calcitonin completely abolished the differentiation induced by OPGL. RANK was detectable in FLG 29.1 and the number of positive cells was increased by OPGL/CSF-1 treatment while reduced by calcitonin. We propose that calcitonin could interact with the OPG/OPGL, and its effects on RANK may explain in part the action of this hormone in suppressing bone resorption.

[Subclinical hyperthyroidism and hypothyroidism]

Currently, technical methods to obtain precocious and reliable diagnosis of thyroid disorders are available for physicians. Therefore today, patients affected by mild hypo- or hyperthyroidism are more often diagnosed when they are still asymptomatic; these mild forms of thyroid disorder are known as subclinical hypo- and hyperthyroidism. In comparison with '80ties, over the last few years we have observed that patients come to endocrinological examination for subclinical forms of thyroid disorders (particularly for hypothyroidism) more frequently than for severe thyroid diseases. However, before to start a therapy, it is necessary for these patients to determine the causes of subclinical hypo- and hyperthyroidism. The main goals of therapy are to reduce the prevalence of cardiac arrhythmia and osteoporosis of patients with subclinical hyperthyroidism, and to slow down the course of arteriosclerotic disease (linked to hyperlipidemia and/or to hyperhomocysteinemia) of patients with subclinical hypothyroidism.

Efficacy and safety of alendronate for the treatment of osteoporosis in diffuse connective tissue diseases in children: a prospective multicenter study

OBJECTIVE

Osteopenia/osteoporosis is being increasingly reported as a complication of many chronic diseases, even in children. In this preliminary study, we evaluated the effect of an oral bisphosphonate (alendronate) on bone mass in children with diffuse connective tissue diseases.

METHODS

Thirty-eight children with low bone mass were treated with alendronate for 1 year; 38 children who had the same primary disorders as the study patients but in a less severe form served as untreated control patients. We were also able to evaluate changes in bone mass (before and after alendronate) in 16 of the treated patients whose bone mineral density (BMD) had been routinely measured before the present study was initiated.

RESULTS

BMD increased by a mean +/- SD of 14.9 +/- 9.8% (P < 0.002 versus baseline) in the treated patients (reaching the normal range in 13 patients), while the BMD was 2.6 +/- 5% (not significant versus baseline) in the control group (15 had a decrease). Most interestingly, there was a large increase in BMD (15.3 +/-9.9%) after alendronate therapy in the 16 children who had their BMD followed up in the year before the study, during which time they had shown little increase in BMD (1.03 +/- 6.3%), and often a decrease. Considering their condition, increases in the height of all patients was satisfactory. No new fractures were observed after alendronate therapy was initiated.

CONCLUSION

Bisphosphonates can be considered essential components of the treatment of secondary osteoporosis, not only in adults, but also in pediatric patients. Alendronate has a positive effect on secondary osteopenia/osteoporosis in children with connective tissue diseases.

Evidence of a linkage disequilibrium between polymorphisms in the human estrogen receptor alpha gene and their relationship to bone mass variation in postmenopausal Italian women

Bone mineral density (BMD), the major determinant of osteoporotic fracture risk, has a strong genetic component. The discovery that inactivation of estrogen receptor alpha (ERalpha) gene is associated with low BMD indicated ERalpha as a candidate gene for osteoporosis. We have investigated the role of three ERalpha gene polymorphisms [intron 1 PVU:II and XBA:I RFLPs and TA dinucleotide repeat polymorphism 5' upstream of exon 1] in 610 postmenopausal women. There was a strong linkage disequilibrium between intron 1 polymorphic sites and also between these sites and the microsatellite (TA)(n) dinucleotide polymorphism, with a high degree of coincidence of the short TA alleles and the presence of PVU:II and XBA:I restriction sites. No significant relationship between intron 1 RFLPs and BMD was observed. A statistically significant correlation between (TA)(n) repeat allelic variants and lumbar BMD was observed (P = 0.04, ANCOVA), with subjects with a low number of repeats (TA < 15) showing the lowest BMD values. We observed a statistically significant difference in the mean +/- SD number of TA repeats between analyzed women with a vertebral fracture (n = 73) and the non-fracture group, equivalent to 2.9 (95% CI 1.56-5.72) increased fracture risk in women with a low number of repeats (TA < 15). We conclude that in this large population sample the (TA)(n) dinucleotide repeat polymorphism at the 5' end of the ERalpha gene accounts for part of the heritable component of BMD and might prove useful in the prediction of vertebral fracture risk in postmenopausal osteoporosis.

Comparison of quantitative calcaneal ultrasound and dual energy X-ray absorptiometry in the evaluation of osteoporotic risk in children with chronic rheumatic diseases

Osteoporosis is a common complication in children with chronic rheumatic diseases (CRD). Although dual energy X-ray absorptiometry (DXA) is increasingly being used to determine bone mineral density (BMD) in children, it exposes the subject to ionizing radiation and does not provide a measure of true bone density; in fact, in growing bones the increase in BMD is mainly caused by the increase in bone size. In recent years, quantitative ultrasound techniques (QUS) have been used in radiation-free assessment of bone density and "bone quality" by measurement of the ultrasound waves attenuation by bone (BUA). In the present study we made a direct comparison of BUA in the calcaneum, determined by the pediatric contact ultrasound bone analyzer (CUBA) with lumbar BMD measured by DXA, in a group of 6-18-year-old patients with CRD. The study group consisted of 53 patients affected with juvenile rheumatoid arthritis (n = 29), systemic lupus erythematosus (n = 13), and juvenile dermatomyositis (n = 11). Mean age was 13.02 +/- 2.69 years. In 22 patients (19 girls, 3 boys) both DXA and CUBA were repeated after 1 year in order to assess the mean percentage rate of BMD and BUA change over this time. Both lumbar spine BMD and calcaneal BUA measurements were lower in the CRD patients compared with a control group (P < 0.001). Calcaneal BUA was significantly correlated (r = 0.83, P < 0.001) with lumbar spine BMD. Age and sex correction (Z-score) did not change the relationship between BUA and BMD (r = 0.80, P < 0.001). A significant correlation between the mean percentage of variation (delta%) of BMD and BUA (r = 0.76, P < 0.001) was also demonstrated in the 22 patients who were evaluated prospectively. Portability, ease of use, lower cost, and absence of radiation make CUBA a promising means of evaluating BMD in children.