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Biomedical subjects

M L Brandi

Publications and source records attributed to M L Brandi.

At least 91 records · Page 5Linked to original sources
PubMed1997

Vitamin D receptor genotypes and intestinal calcium absorption in postmenopausal women.

Several studies have shown that bone mass and bone turnover are genetically determined. This genetic component is thought to be mediated in part by polymorphisms at the vitamin D receptor (VDR) locus, even though the underlying molecular mechanisms are still unknown. To evaluate a possible site of differential action of the VDR gene alleles we examined their correlation with intestinal calcium absorption in 120 Caucasian postmenopausal women (aged 61 +/- 0.6 years). VDR gene polymorphisms for Apa I, Bsm I, and Taq I restriction endonucleases were assessed by Southern blotting analysis. The most common genotypes observed in our population were AaBbTt (37%), AABBtt (20%), aabbTT (15%), AabbTT (15%), and AABbTt (9%). Although there was some evidence of 13% higher lumbar BMD values in aabbTT genotype with respect to AABBtt genotype, this difference of approximately 0.1 g/cm2 did not reach statistical significance, possibly because of the limited number of observations. On the contrary, no relationship was found between genotypes and femoral neck BMD values. Intestinal calcium absorption was significantly lower in BB and tt genotypes than, in bb and TT genotypes, respectively, and in AABBtt genotype than in either aabbTT or AaBbTt genotypes (P = 0.0015 ANOVA). No significant differences in intact PTH, alkaline phosphatase, 25OHD3, and 1, 25(OH)2D3 were found among subjects with different VDR genotypes. These results are consistent with a possible role of VDR alleles on intestinal calcium absorption.

Aged↗
PubMed1997

Natural and synthetic isoflavones in the prevention and treatment of chronic diseases.

The evidence that natural isoflavones protect against several chronic diseases is both observational and experimental. In humans, epidemiologic findings clearly show a higher incidence of some common types of cancer (i.e., breast, prostate, and colon) and of coronary heart diseases in Western populations exposed to limited amounts of soybean isoflavones (i.e., genistein, daidzein) in the diet. Further evidence for cancer and cardiac protection and antiatherogenic effects resulting from soybean isoflavones administration has been noted in various experimental animal models. Isoflavones may also prevent postmenopausal bone loss and osteoporosis. In fact, genistein has been reported to be as active as estrogens in maintaining bone mass in ovariectomized rats. Moreover, the synthetic isoflavone derivative ipriflavone is able to reduce bone loss in various types of animal models of experimental osteoporosis providing a rationale on its use in the prevention and treatment of postmenopausal and senile osteoporosis in humans. The mechanism through which isoflavones may exert the above-mentioned effects seems to depend, at least in part, on their mixed estrogen agonist-antagonist properties. An alternative hypothetical mechanism could derive from other biochemical actions of isoflavones such as inhibition of enzymatic activity, in particular protein kinases, or activation of an "orphan" receptor distinct from the estrogen type I receptor.

Animals↗
PubMed1997

Insulin-like growth factor-I stimulates in vitro migration of preosteoclasts across bone endothelial cells.

Little is known about the factors and the mechanisms involved in preosteoclast emigration from the vasculature. In this study, an in vitro model of bone endothelial lining was mimicked by culturing bone endothelial (BBE) cells at confluence on a 3-microm pore polycarbonate membranes. Preosteoclastic (FLG 29.1) cells were then added on top of the BBE cell monolayer and 10 nM insulin-like growth factor-1 (IGF-I) was added below the supporting membrane. Scanning and transmission electron microscopy were used to evaluate the chemotactic responses of preosteoclastic FLG 29.1 cells towards the IGF-I generated gradient. IGF-I potently stimulated chemotaxis in the FLG 29.1 cells, as shown by the migration of the preosteoclastic cells across the underlying BBE and through the intercellular junctions between adjacent endothelial cells. Subsequently, FLG 29.1 cells penetrated the pores of the supporting membrane and reached the lower face of the membrane. Thus, IGF-I, which is abundantly present in the bone tissue microenvironment, may play a paracrine role in the recruitment of the circulating preosteoclasts from the vascular compartment into the bone tissue. This in vitro model, which mimicks the in vivo phenomenon of preosteoclast extravasation, should prove useful in elucidating the molecular mechanisms that underlie this process.

Adult↗
PubMed1997

Aggressive forms of gastric neuroendocrine tumors in multiple endocrine neoplasia type I.

In recent classifications of gastric endocrine tumors, tumors arising in patients with multiple endocrine neoplasia type 1 (MEN-1) are regarded to be regulated by the concomitant hypergastrinemia resulting from to pancreatic or, most commonly, duodenal gastrinomas and to have a benign behavior. In this article, we report on two cases of MEN-1 gastric neuroendocrine tumors having a fatal course. Case 1 was a young male with hyperparathyroidism and Zollinger-Ellison syndrome and with florid development of multiple gastric carcinoids and multiple duodenal gastrinomas. Metastases occurred in the liver, of exclusive gastric origin, in periduodenal lymph nodes, of exclusive duodenal origin, and in perigastric lymph nodes, of mixed origin. The patient died 48 months after diagnosis. Case 2 was an adult female patient with hyperparathyroidism, adrenocortical disorders, and gastric tumors but no hypergastrinemia. The patient died 3 months after tumor diagnosis. At autopsy, the stomach showed multiple benign carcinoids and two independent neuroendocrine carcinomas not reported before in MEN-1 and massively metastatizing to lymph nodes, liver, and peritoneum. Multiple islet cell tumors mostly producing pancreatic polypeptide were found, whereas gastrinomas were seen in neither the pancreas nor the duodenum. Allelic losses at the MEN-1 gene locus in chromosome 11q13, the mechanism responsible for tumor development in MEN-1 syndrome, were demonstrated in the carcinoid tumors of case 1 and in the neuroendocrine carcinoma of case 2. We conclude that gastric neuroendocrine tumors in patients with MEN-1 may have a poor outcome, they have the same genetic mechanism as MEN-1 tumors in other organs, and they may be independent of the trophic effect of hypergastrinemia.

Adult↗
PubMed1997

Molecular mechanisms of parathyroid hyperplasia and neoplasia.

In the past decade we have witnessed an explosion in our knowledge of the molecular bases of hyperparathyroidism. In spite of the generally benign phenotype of parathyroid tumors, several of the well-recognized mechanisms in tumor biology are applicable to parathyroid tumorigenesis. The concept of evolution of nonneoplastic endocrine hyperplasia into a true tumor is as operative for the parathyroid tissue as for any other neoplasia. The molecular mechanisms underlying parathyroid tumor development, either on the ground of tissue hyperplasia or as neoplasia "ab initio', are starting to be recognized. Oncogenes as well as tumor-suppressor genes and trophic factors appear to play a role in the process of parathyroid tissue growth. The unique opportunity of evaluating at least four distinct organs greatly contributed to the knowledge of the genetic basis of parathyroid tumor development, a field relatively undeveloped in comparison to that of other cancers.

Calcium↗
PubMed1997

Allelic loss in parathyroid tumors from individuals homozygous for multiple endocrine neoplasia type 1.

Homozygosity for the multiple endocrine neoplasia type 1 (MEN1) gene mutation was described in two of three affected siblings of a kindred in which both parents and the third daughter were heterozygotes. Surprisingly, in the two homozygotes, the disease history did not differ from the one of the heterozygotes. In the attempt to unravel genetic differences in parathyroid tumorigenesis between homozygotes and heterozygotes, restriction fragment length polymorphism analysis and microsatellite PCR analysis for loss of heterozygosity (LOH) at the MEN1 gene region on chromosome 11q13 was performed in parathyroid tissues removed at surgery from the mother, her heterozygous sister, and the three siblings. Allelic losses were evidenced in the larger glands of each patient, with a similar pattern of chromosome 11q12-13 losses. The somatic mutation consisted of a large lose of genetic material from chromosome 11. No gross differences exist in the 11q12-13 LOH observed between homozygous and heterozygous carriers. Interestingly, one of the parathyroid tumors from one heterozygote exhibited region of skipped LOH at the 11q12-13 region. The region in the depth of the critical interval retained heterozygosity, whereas those flanking it shared LOH. These findings indicate that inactivation of both copies of the MEN1 gene are not sufficient for parathyroid tumor development in MEN 1 patients and that tumor suppressor genes, other than the MEN1 gene on chromosome 11 or on other chromosomes, can be involved in the pathogenesis of parathyroid tumorigenesis in MEN 1 syndrome.

Chromosome Deletion↗
PubMed1997

HPE cells: a clonal endothelial cell line established from human parathyroid tissue (human parathyroid cell line).

We report the culture and cloning of human endothelial cells derived from parathyroid tissue surgically removed from a patient affected by Multiple Endocrine Neoplasia Type 1 syndrome. These cells, known as HPE, have been isolated and maintained in culture by serial passages for more than 15 months. The clonal cell line grows in a medium containing serum substitutes which favour endothelial cell growth. HPE cells replicate with a mean doubling time of 120 h, showing typical functional and morphological features of endothelial cells, such as uptake of acetylated low density lipoprotein and positive reaction for Factor VIII-Related Antigen. Basic fibroblast growth factor, vascular endothelial growth factor, insulin-like growth factor type I and ascorbic acid stimulate cell proliferation, whereas transforming growth factor beta and heparin act as inhibitory factors. Prostaglandin E2, secretin and epinephrine increased cAMP production, while human parathyroid hormone, histamine and glucagon were inert. Cells were found to express pro-collagen alpha 1 (type I) mRNA. In HPE cells Restriction Fragments Length Polymorphism and PCR analysis did not show allelic loss at chromosome 11q12-13, known to be a typical feature of MEN 1 parathyroid tumors. These cells are the first example of an established normal human clonal cell line with an endothelial phenotype.

Cell Division↗
PubMed1997

Bioeffects of a nitric oxide donor in a human preosteoclastic cell line.

Nitric oxide is a short-lived free radical produced by different isoforms of the enzyme nitric oxide synthase. It regulates a whole range of functions in the body, but little is known about its effects on bone. Rat osteoclasts and a human preosteoclast cell line (FLG 29.1) have been shown to produce nitric oxide and to express nitric oxide synthases. In the present study we investigated the role of a nitric oxide donor, 3-morpholinosydnonimine hydrochloride, on the FLG 29.1 cells. 3-Morpholinosydnonimine hydrochloride has been shown to significantly increase IL6 production and tartrate resistant acid phosphatase activity in FLG 29.1 cells, indicating a positive modulation of osteoclast differentiation. However FLG 29.1 cell adhesion on osteoblast-like cells was significantly inhibited, suggesting an inhibition of osteoclast motility. All these results confirm the bidirectional effect of nitric oxide whose basal production is necessary in promoting osteoclast differentiation, while at high levels it is effective in inhibiting osteoclast activity.

Acid Phosphatase↗
PubMed1996

Clonal analysis by chromosome 11 microsatellite-PCR of microdissected parathyroid tumors from MEN 1 patients.

Loss of heterozygosity (LOH) at chromosome 11q13 loci has been described in the majority of larger parathyroid tumors from patients affected by Multiple Endocrine Neoplasia type 1 (MEN 1) syndrome. Since classical histology of the whole parathyroid gland does not permit a clear morpho-genetic correlation, the clonal composition of abnormal parathyroid tissue was analyzed in DNA obtained from single nodules and non-nodular areas within MEN 1 parathyroid lesions. Microdissected sections were analyzed by chromosome 11q13 microsatellite-PCR for LOH and by patterns of X-inactivation. We detected LOH for chromosome 11q13 loci in at least one microdissected area for each familial MEN 1 patient, but not in the single sporadic case. X-inactivation pattern of two "clonal" tumors exhibited a polyclonal cell composition of these microdissected samples, indicating the existence of a genetic heterogeneity in MEN 1 parathyroid microareas exhibiting a "clonal" pattern for allelic losses.

Adolescent↗
PubMed1996

Catecholamines modulate growth and differentiation of human preosteoclastic cells.

Using a clonal cell line of human osteoclast precursors (FLG 29.1 cells), that after treatment with 12-O-tetradecanoyl phorbol 13-acetate (TPA) show many functional characteristics of osteoclasts, we demonstrated that catecholamines act as inducers of osteoclast maturation in vitro and as stimulators of osteoclast activity via the binding to beta 2 adrenergic receptors. Scatchard analysis of 125I-labelled iodocyanopindolol to untreated (undifferentiated) or TPA-treated (differentiated) FLG 29.1 cells revealed the presence of a single high-affinity site with a Kd value around 24 pM and 8 pM respectively and with superimposable binding capacity (1.18 fmol/mg protein). Catecholamines increased in a dose-dependent fashion the intracellular cyclic AMP (cAMP) accumulation in both undifferentiated and TPA-treated FLG 29.1 cells. Pretreatment of untreated and TPA-treated FLG 29.1 cells with propranolol inhibited the catecholamine effect on cAMP accumulation, while pretreatment with clonidine had no effect. Catecholamines also reduced cell proliferation, increased tartrate-resistant acid phosphatase (TRAcP) activity, interleukin 6 (IL-6) production, multi-nuclearity and response to salmon calcitonin (sCT) in undifferentiated FLG 29.1 cells. In differentiated FLG 29.1 cells only IL-6 release was induced by catecholamine treatment. These findings support a potential role for catecholamines in modulating osteoclast differentiation and mature osteoclast activity.

Adrenergic Antagonists↗
PubMed1996

Intravenous administration of alendronate counteracts the in vivo effects of glucocorticoids on bone remodeling.

The purpose of the investigation was to test the use of alendronate in the therapy of children affected by chronic rheumatic diseases and symptomatic drug-induced osteoporosis. Two courses of alendronate were intravenously administered to four girls with vertebral fractures that were glucocorticoid induced. Improvement of back pain and bone mineral density increase evaluated by DXA and conventional spine X-rays were observed. Our study supports the ABD-induced improvement of the negative effects of long-term therapy on bone mineral density in children with chronic rheumatic diseases.

Adolescent↗
PubMed1996

Histamine receptors and bioeffects on clonal parathyroid endothelial cells.

Using a clonal line of bovine parathyroid endothelial cells (BPE-1) we defined the presence on these cells of a histamine H2 receptor and characterized its pharmacological properties. Interaction of histamine with its receptor induced an increase of cAMP accumulation in a dose- and time-dependent fashion. This effect appears unique for parathyroid endothelial cells, in fact, clonal parathyroid epithelial cells did not exhibit a similar response. No effect of histamine was observed on BPE-1 cell proliferation.

Animals↗
PubMed1996

Characterization and function of the receptor for IGF-I in human preosteoclastic cells.

Using a coculture system, we have recently demonstrated that insulin-like growth factor I (IGF-I) is a mediator of preosteoclastic cell migration toward bone-derived endothelial cells. To better characterize the mechanisms of IGF-I action on preosteoclastic cells we evaluated the expression of type I IGFs receptor in the human leukemic cell line, FLG 29.1, which differentiates toward the osteoclastic phenotype following phorbol ester (TPA) treatment. Scatchard analysis of 125I-labeled IGF-I to FLG 29.1 cells revealed the presence of a single high affinity binding site in both untreated and TPA-treated cells with a similar Kd value (0.3 +/- 0.2 nmol/L and 0.4 +/- 0.1 nmol/L, respectively). In untreated cells, IGF-I binding capacity (1.43 +/- 0.41 fmol/10(6) cells) was significantly (p < 0.05) lower than in TPA-treated cells (2.62 +/- 0.87 fmol/10(6) cells). Competition analyses and crosslinking studies revealed the presence of type I IGF receptor both in untreated and TPA-treated cells. Northern analysis demonstrated that mRNA for IGF-I receptor was expressed by both untreated and TPA-treated FLG 29.1 cells. In addition, FLG 29.1 cells released in the conditioned medium IGFBP-2 and IGFBP-4, whose expression was increased by TPA treatment as demonstrated by ligand and immunoblot analyses. The previous observations of chemotactic action of IGF-I on FLG 29.1 cells was confirmed by ultrastructural observations. Indeed, these cells revealed a marked migratory activity in response to nanomolar concentrations of IGF-I. In addition, the IGF-I receptor alpha IR-3 antiserum inhibited the IGF-I-induced FLG 29.1 cell's migratory activity. These findings clearly show that type IIGF receptor is expressed by osteoclast precursors and that IGF-I induces migration of these through the binding to type I IGF receptors. Binding proteins expressed by osteoclast precursors may play an autocrine role in modulating the IGF-I bioeffects.

Adult↗
PubMed1996

Membrane binding sites and non-genomic effects of estrogen in cultured human pre-osteoclastic cells.

Besides functional estrogen receptors, the presence of signalling cell surface binding sites for 17beta-estradiol (17betaE2) has been reported in osteoblast- and osteoclast-like cells, suggesting that 17betaE2 may influence bone remodelling by a dual mechanism of action: to affect gene expression mediated by the nuclear activity of the steroid-receptor complex, and to initiate rapid responses triggered by a signal-generating receptor on the cell surface. Recently, we demonstrated that the human pre-osteoclastic cell line FLG 29.1 bears functional estrogen receptors. In this study we examined FLG 29.1 cells for the presence of cell surface binding sites for 17betaE2, and whether 17betaE2 could elicit cell signalling. Using a cell-impermeant and fluorescent estrogen conjugate, 17beta-estradiol-6-carboxymethyloxime-bovine serum albumin-fluorescein isothiocyanate, we demonstrated the presence of specific plasma membrane binding sites for 17betaE2. Stimulation of FLG 29.1 cells with low (1 nM) and high (1 microM) doses of 17betaE2 induced a prompt and significant (P < 0.05) increase of cellular pH, as measured in single cells using an image analysis system. In addition, both cAMP and cGMP were significantly increased by 17betaE2 with a dose-dependent response. Finally, a rapid increase of intracellular calcium ion concentration [Ca2+] was also induced by 1 nM 17betaE2, as measured in single cells using an image analysis system. Our findings strongly suggest a non-genomic action of 17betaE2 on osteoclast precursors.

Calcium↗
PubMed1996

Radicular cysts are involved in the recruitment of osteoclast precursors.

In consideration of the close relationship between radicular cysts and alveolar bone, it is important to evaluate the potential involvement of the neighbouring bone tissue in such lesions. In the present study, using cytochemical, immunocytochemical and morphological analyses, presumptive osteoclast precursors were revealed in the connective tissue of radicular cyst capsules. The osteoclastic nature of these cells was postulated by their positive staining for the enzyme tartrate-resistant acid phosphatase (TRAP) and by the expression of vitronectin receptor (VnR) on their cell surface. However, these cells did not express the vacuolar-type proton pump, suggesting that they may represent early osteoclast precursors infiltrating the cyst capsule. Cysts also contained activated small blood vessels whose endothelial cells expressed the VnR. This integrin receptor is important in the adhesion of preosteoclasts to the endothelial lining, a necessary step for their emigration out of the vasculature. Therefore, the intracystic vessels could represent a substrate for preosteoclast recruitment. These precursor cells may then reach the perialveolar bone surface and contribute to bone demolition together with those recruited by the resorbing surfaces. The bone-destroying potential of radicular cysts was confirmed by the presence of numerous osteoclasts with large resorption areas on the perialveolar bone surfaces exposed to the cyst capsules. The resorbed surfaces were usually located around the vascular canals of the Haversian systems.

Acid Phosphatase↗
PubMed1995

Evidence for bioeffects of LY 139478 on the human pre-osteoclastic cell line FLG 29.1.

LY 139478, the hydrochloride salt of LY 117018, is a member of the nonsteroidal antiestrogens, benzothiophene derivatives, described to be full estrogen agonists in bone acting via an estrogen receptor-mediated mechanism. However, the cellular actions of these compounds on bone remodelling need to be established. To investigate the "in vitro" properties of LY 139478 on osteoclast precursors, the human pre-osteoclastic cell line FLG 29.1 was examined for evidence of bioeffects of this compound. Binding studies with tritiated 17 beta-estradiol (17 beta E2) demonstrated that the relative potency of LY 139478 in inhibiting estrogen binding to its receptor was equal to that of 17 beta E2. Significant (p < 0.05) dose-dependent inhibition of cell growth was induced by LY 139478 at 10 nM, 100 nM and 1 microM. Calcitonin-induced cAMP accumulation was significantly increased by low (1 pM) and high (1 microM) doses of both 17 beta E2 and the compound with a dose-dependent response. Differently than estrogen, LY 139478 at high dose significantly reduced IL-6 release by these cells. In addition, pharmacological doses of both 17 beta E2 and LY 139478 activated apoptotic cell death. These findings show that the benzothiophene-derived LY 139478 acts directly on the human pre-osteoclastic cell line FLG 29.1 as an estrogen agonist.

Bone Marrow Cells↗
PubMed1995

Functional estrogen receptors in a human preosteoclastic cell line.

The primary biological effect of the estrogen estradiol-17 beta (17 beta E2) on bone is to decrease bone resorption. However, whether 17 beta E2 affects osteoclast differentiation or function directly or through its action on osteoblasts is unclear. To investigate this question we examined the human preosteoclastic cell line FLG 29.1 for evidence of functional estrogen receptors (ERs). Southern blotting of reverse transcription-PCR amplification products with a 32P-labeled cDNA probe for the human ER mRNA demonstrated that FLG 29.1 cells express ER mRNA. Binding of [3H]17 beta E2 to nuclear ERs was steroid specific with approximately 400 saturable, high affinity (Kd approximately 1 nM) binding sites per cell nucleus. Nuclear ERs covalently labeled with [3H]tamoxifen aziridine showed an apparent molecular weight of 65,000 by SDS/PAGE and Western blotting with the D75 monoclonal antibody to human ER. Pretreatment of cells with 0.1, 1.0, or 10 nM 17 beta E2 induced a dose- and time-dependent specific binding of progesterone to FGL 29.1 cells, and stimulation of the cells with 10 nM and 100 nM 17 beta E2 significantly (P < 0.05) reduced cell proliferation. Transcriptional activity of the ER gene was detected by transient transfection of cells with the pERE-BLCAT plasmid containing the estrogen response element for the vitellogenin A2 gene and the bacterial chloramphenicol acetyltransferase reporter gene. Treatment of FLG 29.1 cells with 10 nM 17 beta E2 increased chloroamphenicol acetyltransferase expression from 5- to 29-fold compared to controls. These observations suggest a potential role for estrogen in osteoclastogenesis.

Adenocarcinoma↗