Biomedical subjects

F Clemente

Publications and source records attributed to F Clemente.

At least 19 recordsLinked to original sources

PubMed1998

The influence of left ventricle assist device and ventilatory support on energy-related cardiovascular variables.

One of the main purposes in using Left Ventricle Assist Devices (LVAD) to assist recovery in patients with heart failure, is to reduce the external work (EW) of the left natural ventricle. The simultaneous presence of mechanical ventilatory support can affect the value of this variable. The aim of our computer simulation was to trace the influence of LVAD on EW, cardiac mechanical efficiency (CME) and pressure volume area (PVA) in the presence of ventilatory support. Pathological conditions of the heart were reproduced. Peripheral systemic arterial resistance (Ras) was also changed to model physiological and pathological states. The influence of mechanical ventilation was introduced by changing levels of mean thoracic pressure. In this way we were able to predict changes of EW, CME and PVA in both ventricles, during ventilatory (mechanical) and cardiovascular (LVAD) support. Our simulation showed that positive thoracic pressure seems to affect the energy-related cardiovascular variables and should be taken into account during the assessment of LVAD effectiveness. Pathological changes of systemic peripheral resistance have a considerable effect on EW, CME and PVA of left ventricle. On the other hand energy-related parameters of the right ventricle are not especially affected by changes in systemic peripheral resistance.

Computer Simulation↗

PubMed1998

Somatostatin in the prevention of recurrent bleeding after endoscopic haemostasis of peptic ulcer haemorrhage: a preliminary report.

OBJECTIVE: Although endoscopic injection therapy provides excellent initial haemostasis in actively bleeding ulcers, the incidence of recurrent haemorrhage is not negligible. The aim of this study was to compare somatostatin, omeprazole and ranitidine in preventing further haemorrhage after endoscopic injection haemostasis. METHODS: Seventy-three patients with major stigmata of ulcer haemorrhage at endoscopy were treated with epinephrine injection and randomly assigned to receive either omeprazole (n = 24) or ranitidine (n = 24) or somatostatin (n = 25). The three groups were similar in all background variables including mean age, clinical and endoscopic features, severity of bleeding and timing of the haemostatic procedure. All patients underwent a second endoscopic look at 48 h. Failures of treatment or retreatment underwent emergency surgery. RESULTS: There were no statistically significant differences between the groups in terms of initial haemostasis, need for emergency surgery, transfusion requirements, length of hospital stay or mortality. Early recurrent haemorrhage was 5/22 (22.7%) in the ranitidine group, 5/23 (21.7%) in the omeprazole group and 2/23 (8.7%) in the somatostatin group. No major side-effect was noted with drug therapy. CONCLUSIONS: The preliminary results suggest that somatostatin might be more effective than ranitidine and omeprazole in the prevention of recurrent haemorrhage following endoscopic injection therapy of bleeding peptic ulcers.

Adult↗

PubMed1997

Exendin-4 agonist and exendin(9-39)amide antagonist of the GLP-1(7-36)amide effects in liver and muscle.

The GLP-1 structurally related peptides exendin-4 and exendin(9-39)amide were found to act, in rat liver and skeletal muscle, as agonist and antagonist, respectively, of the GLP-1(7-36)amide effects on glucose metabolism. Thus, like GLP-1(7-36)amide, exendin-4 increased glycogen synthase a activity and glucose incorporation into glycogen in both tissues and also stimulated exogenous D-glucose utilization and oxidation in muscle. These effects of GLP-1(7-36)amide and exendin-4 were inhibited by exendin(9-39)amide. Our findings provide further support to the proposed use of GLP-1, or exendin-4, as a tool in the treatment of diabetes mellitus. Thus, in addition to the well-known insulinotropic action of the peptides, they act both in liver and in muscle in a manner most suitable for restoration of glucose homeostasis, with emphasis on their positive effects upon glycogen synthesis in the two tissues and on the stimulation of exogenous glucose catabolism in muscle.

Animals↗

PubMed1997

GLP-1 (7-36) amide: effects on glucose transport and metabolism in rat adipose tissue.

In rat adipocytes, GLP-1 (7-36) amide induced an increment in 2-deoxy-glucose uptake, which was additive to that of insulin. Furthermore, in rat fat, GLP-1 (7-36) amide provoked a rise in glycogen synthesis, glucose oxidation and utilization and lipogenesis, the increments being lower than those obtained with insulin. These data support the idea that GLP-1 exerts insulin-like effects on glucose metabolism in rat adipose tissue, as it does in rat hepatocytes and skeletal muscle, although with a lower potency than that of insulin.

Adipose Tissue↗

PubMed1997

Preserved GLP-I effects on glycogen synthase a activity and glucose metabolism in isolated hepatocytes and skeletal muscle from diabetic rats.

To search if biological effects of GLP-I on glucose metabolism in extrapancreatic tissue are present in diabetic states, we have studied the action of GLP-I and insulin on glycogen-enzyme activity, glycogen synthesis, and glucose metabolism in isolated hepatocytes and soleus muscle from adult streptozotocin (STZ)- and neonatal STZ-treated diabetic rats. This work confirms the previously reported insulin-like effects of GLP-I on glucose metabolism in both muscle and liver tissue from normal rats (control). The present study extends those observations to the muscle and liver tissue of diabetic animals. In both muscle and liver tissue, the metabolism of D-glucose, in the absence of added peptides, was more severely affected in adult STZ (IDDM model) than in neonatal STZ (nSTZ; NIDDM model) rats, and the magnitude of hormonal effect on metabolic variables was lower in diabetic rats than in control rats, as a rule. Nevertheless, in liver and muscle tissue of diabetic rats, GLP-I was able to increase glycogen synthase activity, augment the net rate of D-[U-14C]glucose incorporation into glycogen, and increase D-[5-3H]glucose utilization, D-[U-14C]glucose oxidation, and lactate production. In conclusion, GLP-I exerts insulin-like effects on D-glucose metabolism in both muscle and liver tissue in IDDM or NIDDM animal models, and present observations reinforce the view that GLP-I may represent a most promising tool in the treatment of diabetic patients.

Animals↗

PubMed1997

Pancreatic cancer cell regulation by lipids and by basic fibroblast growth factor expression.

High fat intake is a risk factor for pancreatic cancer. Lipids may act either directly or in cooperation with growth-promoting polypeptides. In this study, the role of serum lipids, and mainly the often expressed intracellular basic fibroblast growth factor (bFGF) isoforms in cancer cells, was analyzed in pancreatic tumor cell proliferation. Serum lipids alone induced a 1.9-fold increase of human pancreatic cancer cell growth (p < 0.001). Treatment with bFGF had a weak mitogenic effect (1.2- to 1.3-fold increase) compared with those of insulin and transferrin (1.7- to 1.6-fold increase, respectively). The bFGF expression by a rat pancreatic cancer cell line that was transfected with bFGF cDNAs modified cell lipid contents and induced a higher proliferation rate than that found with the exogenous bFGF. Combined extra- and intracellular bFGFs increased cell growth by two to three times (p < 0.001), regardless the presence of extracellular lipids. The results obtained reflect the direct mitogenic effect of serum lipids and suggest that the endogenous bFGF of high molecular weight may be implicated in pancreatic cancer cell growth. By modifying cell lipids, bFGFs may interfere with other cell functions, like signal transduction.

Animals↗

PubMed1997

[Familial periodic ataxia with myokymia sensitive to acetazolamide: a family case].

INTRODUCTION: Acetazolamide responsive hereditary paroxysmal cerebellar ataxia with myokymia is a type of autosomal dominant cerebellar ataxia which locus was found to be linked to the short arm of chromosome 12 and the etiology is unknown. CLINICAL CASE: A 12 years-old man who suffered from childhood daily episodes of sudden attacks sport induced with giddiness, ataxia and dysarthria for minutes. The familial history shows the same clinical findings in three generations. Intercritical general neurologic evaluation is otherwise normal. The following tests were performed with normal results: Biochemistry, electroencephalogram, cerebral magnetic resonance imaging. The electromyography showed myokymic discharges. The patient's symptoms improve on treatment with acetazolamide immediately. CONCLUSIONS: Acetazolamide responsive hereditary paroxysmal cerebellar ataxia with myokymia needs to think on it to be diagnosed. No typical complementary test (electromyography exception) induces to base diagnosis in the clinical findings, the familial history and the fast clinical improvement after starting treatment with acetazolamide.

Acetazolamide↗

PubMed1997

Technical standards for medical devices. Assisted circulation devices.

The steep rise in the clinical use of high technology biomedical devices and materials, involving multidisciplinary competencies, points out the problem of mutual standards defining, first of all, functional characteristic and tests able to characterise and qualify devices, materials and minimal safety requirements both for patients and operators. Standards defined by consent of the parties or by law are used to this aim. Fast technical development in specific sectors produces besides lack of rules, which must be quickly filled up. The aim of this paper is both the presentation of the approach to problems related to technical standards for biomedical devices and the presentation of the set up of a technical standard for mechanical heart assist devices.

Assisted Circulation↗

PubMed1996

Cells retrovirally transfected with fibroblast growth factor-2 isoforms exhibit altered adenylate cyclase activity and G-protein functionality.

Basic fibroblast growth factor (FGF-2) is synthesized as different molecular mass isoforms all lacking the signal-peptide sequence. The high molecular-mass isoforms (21-24 kDa) possess a signal sequence directing their nuclear translocation. The role of each isoform is still poorly understood, however, modifications in intracellular signalling pathways could explain some effects of these peptides. In order to evaluate the role of FGF-2 isoforms on the adenylate cyclase (AC) signalling pathway, we retrovirally infected a rat pancreatic cell line (AR4-2J) with point-mutated FGF-2 cDNAs, allowing the expression of the 18 (A5 cells) or 22.5 kDa isoform (A3 cells) at a low level. In membrane preparations of A3 cells, unscheduled expression of the 22.5 kDa FGF-2 isoform induced a 2-fold decrease in both basal and forskolin-stimulated AC activity. Studies carried out on intact cells also showed decreased accumulation of cAMP in A3 cells in the presence of the phosphodiesterase inhibitor 3-isobutyl-1-methylxanthine. Both FGF-2 peptides also induced functional modifications of G-proteins without affecting their levels. The 22.5 kDa peptide led to enhanced ADP-ribosylation of both alpha(s)-subunits in vitro, whereas the expression of the low molecular-mass 18 kDa peptide resulted in a 2-fold increase in alpha12 and alpha0 ADP-ribosylations. Furthermore, control CAT cells (AR4-2J cells transfected with the retrovirus containing the chloramphenicol acetyltransferase gene) and A5 cells were growth-inhibited by 8-Br-cAMP, in contrast to A3 cells. These data provide evidence that the expression of FGF-2 peptides could play a role in cell functions by modifying the AC signalling pathway. FGF-2 peptides are able to modulate both AC activity and the regulatory G-proteins. Finally FGF-2 expression may interfere with cAMP-regulated cell proliferation.

8-Bromo Cyclic Adenosine Monophosphate↗

PubMed1996

Differential regulation of fibroblast growth factor (FGF) receptor-1 mRNA and protein by two molecular forms of basic FGF. Modulation of FGFR-1 mRNA stability.

To evaluate possible functional differences between basic fibroblast growth factor (FGF) 2 isoforms we analyzed the effects of the 18-kDa FGF-2 which mainly localizes in the cytosol and that of the nuclear-targeted 22.5-kDa form on FGF receptors (FGFR) expression. These peptides were expressed at low amounts through a retroviral-infection system. Point mutated FGF-2 cDNAs under the control of the beta-actin promoter were used to infect a pancreatic cell line (AR4 2J) which does not produce FGF-2. Saturation and competition binding studies with 125I-FGF-2 revealed a 3-fold increase in both high and low affinity receptors in cells expressing the 22.5-kDa form and a 2-fold increase only in the high affinity receptors in cells producing the 18-kDa form. Kd values and molecular weights of the high affinity receptors were unaffected. Increasing cell densities or cell treatment with exogenous FGF-2 resulted in FGFR down-regulation as in control cells. Neutralizing anti-FGF-2 antibodies and suramin did not affect receptor density in control and in cells producing the 22.5-kDa form but further increased by 60 and 80%, respectively, the receptor level in cells synthesizing the 18-kDa form. These data suggest the involvement of the intracellular stored FGF-2 in FGFR up-regulation. Although all cells expressed FGFR-1, -2, and -3 mRNA only the FGFR-1 transcript was found increased, 6-fold in 22.5-kDa expressing cells and 3-fold in cell producing the shortest secreted isoform. The increase in FGFR-1 mRNA levels in the 22.5-kDa expressing cells was due to enhanced stability of the transcript. Confocal microscopy detected the presence of FGFR-1 at the cell surface whereas secretory isoforms of the receptor were not observed. Reverse transcriptase-polymerase chain reaction did not reveal significant differences in the expression of FGFR-1 variants. In the 22.5-kDa expressing cells exogenous FGF-2 evoked a stronger translocation of the calcium-phospholipid-dependent PKC. These results indicate that the transfected FGF-2 isoforms up-regulated FGFR-1 mRNA and protein. The 22.5-kDa form acted by increasing FGFR-1 mRNA stability enhancing cell responses to exogenous FGF-2.

Animals↗

PubMed1996

Inositolphosphoglycans and diacyglycerol are possible mediators in the glycogenic effect of GLP-1(7-36)amide in BC3H-1 myocytes.

A potent glycogenic effect of GLP-1(7-36)amide has been found in rat hepatocytes and skeletal muscle, and specific receptors for this peptide, which do not seem to be associated with the adenylate cyclase-cAMP system, have been detected in these tissue membranes. On the other hand, inositolphosphoglycan molecules (IPGs) have been implicated as second messengers of the action of insulin. In this work, we have found, in differentiated BC3H-1 myocytes, specific binding of [125I]GLP-1(7-36)amide, and a stimulatory effect of the peptide on glycogen synthesis, confirming the findings in rat skeletal muscle. Also, GLP-1(7-36)amide modulates the cell content of radiolabelled glycosylphosphatidylinositols (GPIs) and increases the production of diacylglycerol (DAG), in the same manner as insulin acts, indicating hydrolysis of GPIs and an immediate and short-lived generation of IPGs. Thus, IPGs and DAG could be mediators in the glycogenic action of GLP-1(7-36)amide in skeletal muscle.

Animals↗

PubMed1996

Inositolphosphoglycans are possible mediators of the glucagon-like peptide 1 (7-36)amide action in the liver.

A potent glycogenic effect for GLP-1(7-36)amide has been found in rat hepatocytes and skeletal muscle, and the specific receptors detected for GLP-1(7-36)amide in these tissue membranes do not seem to be associated to adenylate cyclase. On the other hand, inositolphosphoglycan molecules (IPGs) have been implicated as second messengers in the action of insulin. In a human hepatoma cell line (HEP G-2), we have observed the presence of [125I]GLP-1(7-36)amide specific binding, and a stimulatory effect of the peptide upon glycogen synthesis, confirming the findings in isolated rat hepatocytes. Also, GLP-1(7-36)amide modulates the cell content of radiolabelled glycosylphosphatidylinositols (GPIs), in the same manner as insulin, indicating hydrolysis of GPIs and an immediate and short-lived generation of IPGs. Thus, IPGs could be mediators in the GLP-1(7-36)amide glycogenic action in the liver.

Animals↗

PubMed1996

Neonatal outcome and obstetric complications in women with gestational diabetes: effects of maternal body mass index.

OBJECTIVE: To evaluate in a selected population the clinical characteristics (time of diagnosis, different treatment, metabolic parameters, etc.) of gestational diabetes in relation to prepregnancy body mass index (BMI) and the influence of BMI on neonatal outcome. DESIGN: This study was retrospectively led using a computerized data system for all deliveries that occurred at the Departments of Obstetrics and Gynecology of the University of Pisa (Italy) from 1 January 1987 to 31 December 1992. SUBJECTS: 93 women with GDM and 110 control subjects divided into three groups according to their pre-pregnancy BMI: normal weight (Nw), overweight (Ow) and obese (Ob). MEASUREMENTS: Time of diagnosis, mode of treatment and metabolic control of GDM; time and mode of delivery, neonatal outcome (macrosomia, respiratory distress syndrome, hyperbilirubinemia, hypoglycemia, polycythemia, hypocalcemia). RESULTS: GDM was diagnosed earlier in Ow and Ob than in Nw (p < 0.01) and insulin treatment was used in 86% of Ob-GDM, 91% of Ow-GDM and in 77% of Nw-GDM women (p < 0.001). Preterm deliveries and cesarean sections resulted significantly increased in all BMI categories of GDM patients with respect to matched normal controls. Prevalence of neonatal macrosomia was higher in GDM patients (44.6%) compared with normal controls (15.4%) and correlated (p > 0.01) with prepregnancy BMI in both groups. The body weight increase during pregnancy was not associated with neonatal macrosomia. CONCLUSIONS: The degree of overweight is associated with an earlier diagnosis of GDM; prepregnancy BMI is more predictive of macrosomia than weight gain, both in control and GDM women; GDM seems to play the most important role in increasing the possibility of the occurrence of macrosomia.

Body Mass Index↗

PubMed1996

Expression of two FGF-2 isoforms in pancreatic acinar cells (AR4-2J). Intracellular localization and role in the regulation of the extracellular matrix biosynthesis.

Fibroblast growth factor (FGF-2) is a multifunctional growth factor. In cells producing this factor, FGF-2 is synthesized as different molecular weight isoforms lacking the signal peptide sequence for secretion. All forms are highly concentrated in cells. The presence of a nuclearization signal sequence in some isoforms suggests the involvement of these isoforms in cell functions bypassing the cell surface receptors. Our aims were to better define the intracellular localizations of the FGF-2 isoforms by immunocytochemistry and confocal microscopy and to analyze whether these isoforms were involved in the expression of extracellular matrix (ECM) components. We chose the pancreatic acinar cell line AR4-2J since it does not synthesize FGF-2. These cells were retrovirally transfected by point-mutated FGF-2 cDNAs. The cell lines obtained produced either the 18 kDa form (A5 cells) or the 22.5 kDa form (A3 cells). In A5 cells, the 18 kDa form was found in the cytoplasm, on the cell surface reflecting its secretion, and in the nucleoli. Parental AR4-2J cells treated with exogenous FGF-2 exhibited identical localizations, suggesting that in A5 cells the 18 kDa form followed the same translocation pathways than the exogenous FGF-2. By contrast, in A3 cells the 22.5 kDa form was predominantly localized in the nucleoplasm but was undetectable on the cell surface, suggesting its direct translocation to the nucleus. Northern and Western blot analysis showed that cells expressing the high molecular weight form exhibited a decrease of laminin B1 protein level and mRNA stability. In contrast, collagen IV and fibronectin expressions were unmodified either in FGF-2-transfected cells or in parental cells treated by exogenous FGF-2. Thus, these data indicate that: 1) 18 and 22.5 kDa FGF-2 are preferentially localized in different nuclear compartments and 2) the high molecular weight form plays a role on the expression of some ECM components.

Animals↗

PubMed1995

Glucagon-like peptide-1 binding to rat skeletal muscle.

We have found [125I]glucagon-like peptide-1(7-36)-amide-specific binding activity in rat skeletal muscle plasma membranes, with an estimated M(r) of 63,000 by cross-linking and SDS-PAGE. The specific binding was time and membrane protein concentration dependent, and displaceable by unlabeled GLP-1(7-36)-amide with an ID50 of 3 x 10(-9) M of the peptide; GLP-1(1-36)-amide also competed, whereas glucagon and insulin did not. GLP-1(7-36)-amide did not modify the basal adenylate cyclase activity in skeletal muscle plasma membranes. These data, together with our previous finding of a potent glycogenic effect of GLP-1(7-36)-amide in rat soleus muscle, and also in isolated hepatocytes, which was not accompanied by a rise in the cell cyclic AMP content, lead use to believe that the insulin-like effects of this peptide on glucose metabolism in the muscle could be mediated by a type of receptor somehow different to that described for GLP-1 in pancreatic B cells, where GLP-1 action is mediated by the cyclic AMP-adenylate cyclase system.

Adenylyl Cyclases↗

PubMed1995

Physiological effect of glucagon in human isolated adipocytes.

In human isolated adipocytes, glucagon induces a dose dependent increment of the glycerol release, which is already observed at physiological concentrations of the hormone. Furthermore, glucagon at 10(-8) M, significantly stimulates the adenylate cyclase activity in both non-solubilized and solubilized fat plasma membranes, and at already 10(-11) M, a significant increment of the adipocyte cAMP content is observed. These data support previous in vivo positive results indicating that glucagon plays a role in human fat metabolism.

Adenylyl Cyclases↗

PubMed1995

Glucagon-like peptide-1 binding to rat hepatic membranes.

We have found [125I]glucagon-like peptide (GLP)-1(7-36)amide specific binding activity in rat liver and isolated hepatocyte plasma membranes, with an M(r) of approximately 63,000, estimated by cross-linking and SDS-PAGE. The specific binding was time- and membrane protein concentration-dependent, and equally displaced by unlabelled GLP-1(7-36)amide and by GLP-1(1-36)amide, achieving its ID50 at 3 x 10(-9) M of the peptides. GLP-1(7-36)amide did not modify the basal or the glucagon (10(-8) M)-stimulated adenylate cyclase in the hepatocyte plasma membranes. These data, together with our previous findings of a potent glycogenic effect of GLP-1(7-36)amide in isolated rat hepatocytes, led us to postulate that the insulin-like effects of this peptide on glucose liver metabolism could be mediated by a type of receptor probably different from that described for GLP-1 in pancreatic B-cells or, alternatively, by the same receptor which, in this tissue as well as in muscle, uses a different transduction system.

Animals↗

PubMed1994

Glucagon-like peptide 1: a potent glycogenic hormone.

GLP-1(7-36)amide is an insulinotropic peptide derived from the intestinal post-translational proglucagon process, the release of which is increased mainly after a carbohydrate meal; also, its anti-diabetogenic effect in normal and diabetic states has been reported. In this study, GLP-1(7-36)amide stimulates the formation of glycogen from glucose in isolated rat hepatocytes, such a glycogenic effect being achieved with physiological concentrations of the peptide. The GLP-1(7-36)amide-induced glycogenesis is abolished by glucagon, and it is accompanied by stimulation of the glycogen synthase alpha activity and by a decrease in the basal and glucagon-stimulated cyclic AMP content. These findings could explain, at least in part, the GLP-1(7-36)amide insulin-independent plasma glucose lowering effect.

Animals↗