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Biomedical subjects

S Benvenuti

Publications and source records attributed to S Benvenuti.

At least 55 records · Page 3Linked to original sources

[The medical therapy of chronic pancreatitis. Problems, progress and outlook].

The aims of medical therapy in chronic pancreatitis are mainly to relieve the recurrent pain and to correct any malabsorption secondary to digestive insufficiency resulting from deficient exocrine pancreatic function. The treatment of the pain initially involves the use of dietary measures and analgesic drugs. The results of the use of pancreatic extracts and somatostatin reported in the literature are controversial, as are those of coeliac plexus block. Of unquestionable efficacy, at least in the short to medium term, are surgical decompression interventions in patients, with pain refractory to these measures and who present significant dilation of Wirsung's duct at ERCP. Endoscopic decompression constitutes an alternative to surgical decompression. In view of the transitory results of endoscopic decompression, which, in any event, should be implemented only by endoscopists possessing the necessary experience and expertise, the use of this technique may perhaps be targeted at carefully selected patients to be submitted to surgical decompression. As far as maldigestion is concerned, which occurs only when the pancreatic functional deficit reaches 90% or more, replacement therapy with pancreatic extracts must be resorted to. Multi-Unit Dose preparations are to be preferred, consisting in gastro-protected microspheres measuring not more than 2 mm in diameter and containing high doses of lipase, since at least 30,000 I.U. of lipase are required in the post-prandial phase for reasonably satisfactory correction of the steatorrhoea. Should this fail to prove effective, it is good policy to add antisecretory drugs (H2-antagonists, proton-pump inhibitors).

Chronic Disease↗

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↗

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↗

In vitro structural and functional relationships between preosteoclastic and bone endothelial cells: a juxtacrine model for migration and adhesion of osteoclast precursors.

The role of vascularization in the process of bone resorption has not been clarified. The interactions between vascular endothelium and osteoclast progenitors were analyzed using clonal cell lines of bone-derived endothelial and preosteoclastic cells. Insulin-like growth factor I is a major chemotactic stimulator of preosteoclastic cell migration mediated by bone endothelial cells. Osteoclast precursors rapidly adhered to bone endothelial monolayers. This phenomenon appeared to be cell-specific and mediated through the binding of vitronectin and fibronectin receptors to fibronectin. In addition, direct contact with bone endothelial cells induced osteoclast progenitors to differentiate into more mature elements, with the tendency to cluster together to form large multinucleated cells. These findings demonstrated specific in vitro interactions between bone endothelial cells and osteoclast progenitors, offering a new model for understanding the molecular mechanisms which direct the processes of osteoclast recruitment and ontogeny.

Animals↗

Interactions between ipriflavone and the estrogen receptor.

Estrogen replacement therapy is effective in the prevention of postmenopausal osteoporosis, and a direct action of 17-beta-estradiol (17 beta E2) on osteoblastic and osteoclastic cells has been demonstrated. The inhibition of bone resorption by ipriflavone (IP), an isoflavone derivative devoid of estrogenic properties but active in potentiating the effects of estrogen on bone tissue, has been shown in in vitro and in vivo studies and confirmed by clinical data. To investigate the molecular mechanisms that underlie IP effect, we studied the possible interactions of IP and its four main in vivo metabolites (I, II, III, and V) with the estrogen receptor (ER) in the human preosteoclastic cell line FLG 29.1, whose growth and function are modulated by the compound. In parallel experiments, the human breast cancer cell line MCF7 was also analyzed. IP binding sites were demonstrated in the nuclear fraction of FLG 29.1 cells. 17 beta E2 and other steroid compounds failed to displace IP binding to intact FLG 29.1 cells. Similarly, IP and metabolites I, III, and V were not able to displace 17 beta E2 binding to intact MCF7 cells, whereas metabolite II showed an IC50 of 61 nM. 17 beta E2 binding to FLG 29.1 cells was increased after preincubation with metabolites I, III, and V. IP and its metabolites did not induce ER-dependent gene expression in FLG 29.1 and MCF7 cells transfected with a reporter gene and an estrogen response element (ERE).(ABSTRACT TRUNCATED AT 250 WORDS)

Binding, Competitive↗

Functional and structural interactions between osteoblastic and preosteoclastic cells in vitro.

Osteoblasts are involved in the bone resorption process by regulating osteoclast maturation and activity. In order to elucidate the mechanisms underlying osteoblast/preosteoclast cell interactions, we developed an in vitro model of co-cultured human clonal cell lines of osteoclast precursors (FLG 29.1) and osteoblastic cells (Saos-2), and evaluated the migratory, adhesive, cytochemical, morphological, and biochemical properties of the co-cultured cells. In Boyden chemotactic chambers, FLG 29.1 cells exhibited a marked migratory response toward the Saos-2 cells. Moreover, they preferentially adhered to the osteoblastic monolayer. Direct co-culture of the two cell types induced: (1) positive staining for tartrate-resistant acid phosphatase in FLG 29.1 cells; (2) a decrease of the alkaline phosphatase activity expressed by Saos-2 cells; (3) the appearance of typical ultrastructural features of mature osteoclasts in FLG 29.1 cells; (4) the release into the culture medium of granulocyte-macrophage colony stimulating factor. The addition of parathyroid hormone to the co-culture further potentiated the differentiation of the preosteoclasts, the cells tending to fuse into large multinucleated elements. These in vitro interactions between osteoblasts and osteoclast precursors offer a new model for studying the mechanisms that control osteoclastogenesis in bone tissue.

Adult↗

The homing behaviour of Cory's shearwaters (Calonectris diomedea) studied by means of a direction recorder

A direction recorder, which can be carried by a flying bird on its back, has been used for the first time on a wild species. The device can detect and record the direction in which a bird is heading during flight. Cory's shearwaters (Calonectris diomedea) were moved from their nesting colony to five different sites and fitted with direction recorders, and four homing flight paths were obtained. Our data show that the displaced birds were able to assume and maintain a homeward course soon after release over large areas of open sea, completely devoid of guiding features; topographical elements are, therefore, not necessary for correct orientation.

Journal Article↗

[High-dose vecuronium in "open-eye" emergency surgery].

BACKGROUND: Succinylcholine is contraindicated in "open eye" surgery because it raises intraocular pressure. High dose vecuronium reduces onset time for orothracheal intubation. The objective of the study was to evaluate clinical efficacy of high dose vecuronium (0.2 and 0.3 mg/kg) and its effects on intraocular pressure for its use in "open eye" emergency surgery. DESIGN: Randomized, prospective, clinical trial. SETTING: Eye clinic of University of Florence. PATIENTS: 40 patients scheduled for vitrectomy, excluding any drug action on IOP, subdivided into two groups: the first (20 patients) had 0.2 mg/kg vecuronium at the induction of anaesthesia, the second (20 patients) 0.3 mg/kg. ANAESTHESIA: Premedication: atropine 0.01 mg/kg. Preinduction: fentanyl 3 micrograms/kg. Induction: thiopentone 4 mg/kg+ after 1 minute) vecuronium. Orotracheal intubation after 90". MEASURES: IOP was obtained by applanation tonometry in three time: T0 = preinduction; T1 = 50" after thiopentone; T2 = 50" after vecuronium. Systodiatolic pressure was obtained at the same time. Neuromuscular function was evaluated by vocals cord relaxation and by clinical evaluation of response to ulnar nerve stimulation (by train of four). STATISTIC: "t"-Student. MAIN RESULTS AND CONCLUSIONS: No modification of IOP and systodiastolic pressure was caused by administration of vecuronium; no statistic differences are between T1 and T2 values. All patients were intubated after 90" vecuronium administration; the vocal cord relaxation was maxima in all the patients. High dose vecuronium seems to be useful in "open eye" emergency surgery when succinylcholine is contraindicated.

Adult↗

Binding and bioeffects of Ipriflavone on a human preosteoclastic cell line.

Ipriflavone, a synthetic isoflavone derivative, reduces bone resorption by inhibiting osteoclasts activity. In order to evaluate the role of Ipriflavone on osteoclast growth and differentiation, we tested Ipriflavone and its four "in vivo" main metabolites (Metabolites I, II, III, and V) on a clonal population of human osteoclast precursor cells (FLG 29.1). Pharmacological doses of Ipriflavone and Metabolite III were able to inhibit cell proliferation and interleukin 6 release. In co-cultures of FLG 29.1 cells and osteoblastic (Saos-2) cells Ipriflavone at 1 microM dose inhibited the adhesion of FLG 29.1 cells to the osteoblastic monolayer and reduced the immunocytochemical reaction of the vitronectin receptor. Binding studies with tritiated Ipriflavone showed the presence of a single specific binding site, wtih a Kd of about 70 nM and a binding capacity of 8 fmol/10(6) cells. These results demonstrate a direct effect of Ipriflavone and of Metabolite III on the human osteoclast precursor cell line FLG 29.1.

Cell Adhesion↗

Characterization, regulation, and function of specific cell membrane receptors for insulin-like growth factor I on bone endothelial cells.

It is now widely accepted that insulin-like growth factor-I (IGF-I) has a local regulatory role in bone remodeling. IGF-I has also been demonstrated to regulate proliferation of bone-derived endothelial cells. Such studies suggest a role of IGF-I in skeletal angiogenesis. Using BBE cells, a bovine bone endothelial cell line, we characterized the kinetics and chemical properties of IGF-I receptors and examined the effect of IGF-I on bone endothelium migration. Two classes of binding sites with high affinity for IGF-I were detected by binding experiments on bone endothelial cells. Both competition analyses and cross-linking studies revealed the presence of type I IGF receptor in bone endothelial cells. Moreover, these cells produced and released authentic IGF-I into the medium, as evidenced by radioimmunoassay analyses of gel-filtered conditioned media. Both IGF-I binding capacity and release decreased either with increases in cell number or after treatment with 17 beta-estradiol (17 beta E2) and parathyroid hormone (PTH). Both hormones also inhibited chemotactic responses of bone endothelial cells to IGF-I. Taken together, these results strongly suggest that IGF-I, a growth factor that promotes the proliferation of various bone cell types, also induces growth and chemotactic responses in bone endothelium acting through the type I IGF receptor. This may be part of a generalized response of bone cells to IGF-I that facilitates cell migration.

Analysis of Variance↗

Chronic gastritis, intestinal metaplasia, dysplasia and Helicobacter pylori in gastric cancer: putting the pieces together.

Chronic gastritis may favour the development of gastric cancer more as a condition than as precancerous lesion. Since, in most cases, it is pathologically correlated with Helicobacter pylori infection, it is reasonable to postulate at least an indirect role for this organism in the pathogenesis of gastric cancer. H. pylori, however, is only one of the risk factors involved, in that additional factors (excess salt, cigarette smoking, deficiency of foodstuffs with an antioxidizing effect) may facilitate the malignant transformation of chronic atrophic gastritis into intestinal-type gastric cancer. Gastric carcinogenesis therefore presents itself as a multifactorial, multistage process, furthered by the occurrence of precancerous lesions which are usually interrelated (type-III intestinal metaplasia, severe dysplasia) and by functional alterations such as achlorhydria, which, though it is not enough in itself to cause gastric cancer, promotes abnormal intragastric bacterial development, a condition which may be followed by abnormal intragastric formation of cancerogenous nitroso compounds. The existence of a close correlation between both gastric cancer and H. pylori infection and low socio-economic and hygienic status of the population lends further strength to the hypothesis that an "H. pylori factor" is involved in gastric carcinogenesis. Consequently, to reduce the risk of gastric cancer, various strategies have been devised to prevent H. pylori infection (improvement in socio-environmental conditions, anti-H. pylori vaccine) and/or to eradicate the organism (by means of therapeutic regimens including antimicrobial agents, which, however, can be implemented only in patients who have not developed diffuse atrophy and/or dysplasia, in whom H. pylori may no longer be detectable). Definitive proof of the real extent of the relationship between H. pylori and gastric cancer and of the efficacy of therapeutic and preventive measures can be provided only by controlled trials in populations with a high prevalence of chronic non-atrophic gastritis which are difficult to organize.

Chronic Disease↗

[Liposarcoma of the spermatic cord: a clinical case].

A case of spermatic cord liposarcoma is reviewed. Radical orchiectomy is an adequate form of treatment while retroperitoneal lymphadenectomy and adjunctive radiotherapy or chemotherapy appear to be controversial. A close follow-up is mandatory to detect early relapses or distant metastasis.

Genital Neoplasms, Male↗

Inhibition of mutagenicity in Salmonella typhimurium by Glycyrrhiza glabra extract, glycyrrhizinic acid, 18 alpha- and 18 beta-glycyrrhetinic acids.

The effects of Glycyrrhiza glabra L. extract, glycyrrhizinic acid, 18 alpha- and 18 beta-glycyrrhetinic acids on the mutagenicity of the ethyl methanesulfonate, N-methyl-N'-nitro-N-nitrosoguanidine, and ribose-lysine Maillard model systems were investigated by using the Salmonella/microsome reversion assay. The protocol used allowed us to detect desmutagenic and antimutagenic activity and to avoid false positive results due to toxicity. For all the compounds tested, no desmutagenic activity was observed against ethyl methanesulfonate and N-methyl-N'-nitro-N-nitrosoguanidine; only Glycyrrhiza glabra extract showed antimutagenic activity against ethyl methanesulfonate. On using the ribose-lysine mutagenic browning mixture, the desmutagenic activities of the Glycyrrhiza glabra extract, glycyrrhizinic acid, 18 alpha- and 18 beta-glycyrrhetinic acids were observed. 18 beta-Glycyrrhetinic acid was the most active compound. Glycyrrhiza glabra extract also exhibited antimutagenic activity against ribose-lysine.

Antimutagenic Agents↗

Chordoma with multiple skin metastases.

We report a case of sacral chordoma with numerous skin metastases. Histologically they show the typical 'physaliform cells' expressing simultaneously cytokeratin, S-100 protein, epithelial membrane antigen and vimentin immunoreactivity.

Chordoma↗

Adhesion, growth, and matrix production by osteoblasts on collagen substrata.

A number of studies have demonstrated the pivotal role of collagen molecules in modulating cell growth and differentiation. In order to analyze the direct effects of collagen type I on the osteoblastic phenotype, we have devised an in vitro culture system for studying the interactions between bovine collagen type I and Saos-2 cells, a human osteoblastic cell line. Saos-2 cells were cultured both on top of collagen-coated culture dishes as well as inside a three-dimensional collagen network. Plating on dishes treated with collagen induced maximal adhesion of Saos-2 cells after 24-hour incubation. Cells cultured on collagen gel matrix expressed about 2.5-fold more alkaline phosphatase when compared with untreated plastic dishes. On collagen-coated dishes the responsiveness of Saos-2 cells to parathyroid hormone was decreased, whereas no modifications were observed in the effect of vasoactive intestinal peptide on these cells. Using a microfluorimetric measurement of DNA, an increase of proliferation was observed in Saos-2 cells cultured on collagen gel. Saos-2 cells were also able to colonize collagen sponges and in this three-dimensional network they were able to synthesize osteocalcin, as assessed both by immunocytochemistry and radioimmunoassay. In this study we have demonstrated that bovine collagen type I exhibits favorable effects on attachment and functional and growth activities of a human osteoblastic cell line, encouraging its use as a bone graft material.

Alkaline Phosphatase↗

Activity of polyphenolic crude extracts as scavengers of superoxide radicals and inhibitors of xanthine oxidase.

In view of the pharmacological interest in phenolic substances, we have determined the total amount of anthocyanins and polyphenols present in the berries of several cultivars of Ribes, Rubus, and Vaccinium genera. The in vitro antiradical activity of the crude extracts on chemically-generated superoxide radicals as well as the inhibitory activity towards the enzyme xanthine oxidase were studied. All the crude extracts examined showed a remarkably high activity towards chemically-generated superoxide radicals. The activities were greater than those expected on the basis of the quantities of anthocyanins and polyphenols present in the samples. Furthermore, the extracts showed a certain inhibitory activity towards xanthine oxidase. Ribes nigrum extracts exhibit the highest activity, being the richest in both anthocyanins and polyphenols. On the other hand, Ribes rubrum extracts seem to contain more active substances than the other crude extracts.

Flavonoids↗