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Biomedical subjects

G Pugliese

Publications and source records attributed to G Pugliese.

At least 37 records · Page 2Linked to original sources
PubMed1998

Are US hospitals making progress in implementing guidelines for prevention of Mycobacterium tuberculosis transmission?

BACKGROUND: Outbreaks of tuberculosis (TB) in hospitals have occurred when the Centers for Disease Control and Prevention (CDC) guideline recommendations for preventing the transmission of Mycobacterium tuberculosis were not fully implemented. OBJECTIVE: To determine whether US hospitals are making progress in implementing the CDC guidelines for preventing TB. METHODS: In 1992, we surveyed all public (city, county, Veterans Affairs, and primary medical school-affiliated) US hospitals (n = 632) and 444 (20%) random samples of all private hospitals with 100 beds or more. In 1996, we resurveyed 136 random samples (50%) of all 1992 respondent hospitals with 6 or more TB admissions in 1991. RESULTS: Of the 1076 hospitals surveyed in 1992, 763 (71%) respondents returned a completed questionnaire. Among these, 536 (71%) of 755 reported having rooms that met CDC criteria for acid-fast bacilli isolation, ie, negative air pressure, 6 or more air exchanges per hour, and air directly vented to the outside. The predominant respiratory protective device for health care workers was nonfitted surgical mask and attending physicians were infrequently (50%) included in tuberculin skin-testing programs. In the 1996 resurvey, 103 (76%) of 136 respondents returned a completed questionnaire. Of these, 99 (96%) reported having rooms that met CDC criteria for acid-fast bacilli isolation. The N95 respiratory protective devices were predominantly used by health care workers, and attending physicians were increasingly (69%) included in the hospitals' tuberculin skin-testing programs. CONCLUSIONS: Most US hospitals are making progress in the implementation of CDC guidelines for preventing the transmission of M tuberculosis.

Centers for Disease Control and Prevention, U.S.↗
PubMed1998

Eicosanoid synthesis in peripheral blood monocytes: a marker of disease activity in lupus nephritis.

A typical feature of lupus nephritis is glomerular and interstitial leukocyte infiltration. In search of a serological marker of renal disease activity, we examined prostaglandin endoperoxide synthetase (PGHS) activity in peripheral-blood monocytes isolated from 5 healthy subjects and 11 untreated patients with biopsy-proven lupus nephritis, using radioimmunoassay of prostaglandin E2 (PGE2) and thromboxane B2 (TxB2) released during 24-hour cultures with selective stimuli/inhibitors. Unstimulated basal PGE2 and TxB2 synthesis, reflecting in vivo PGHS activity, was greater in the five patients with active renal involvement (World Health Organization [WHO] classes IVb-c) and the six lupus patients without active disease than in the five healthy subjects (TxB2, 2,643+/-198 [standard error], 2,015+/-190, 1,548+/-295 pg/10(6) cells, respectively). Escherichia coli lipopolysaccharide (LPS; 10 microg/mL) potently induced TxB2 or PGE2 synthesis in healthy controls (+255%+/-76% and +611%+/-190%, +688%+/-234% and +3,189%+/-154%; 4 to 24 hours, respectively), an effect abolished by 5 micromol/L of dexamethasone (DEX) or by 5 micromol/L of the protein synthesis inhibitor cycloheximide (CHX). Responses to LPS were reduced in lupus patients without disease activity and reduced even further in those with active nephritis. This may be related to substrate depletion or feedback functional inhibition of the inducible isoform of PGHS. Our assay may prove useful in the early detection of kidney disease activity in lupus erythematosus.

Adult↗
PubMed1997

High glucose level inhibits capacitative Ca2+ influx in cultured rat mesangial cells by a protein kinase C-dependent mechanism.

In cultured mesangial cells (MC), capacitative Ca2+ influx via store-operated channels (SOC) is potentiated by agents that release Ca2+ from intracellular stores, and inhibited by protein kinase C (PKC). Cells grown under high glucose conditions, as a model of the diabetic microenvironment, display reduced Ca2+ signalling in response to vasoconstrictors, probably due to downregulation by elevated PKC activity. Since SOC might be relevant to this phenomenon, we assessed Ca2+ influx by microfluorometry of fura-2-loaded rat MC cultured for 5 days in normal (5.5 mmol/l, NG) or high glucose (30 mmol/l, HG). The addition of 1-10 mmol/l Ca2+ to NG cells equilibrated in Ca(2+)-free media induced an immediate Ca2+ influx with a free cytosolic Ca2+ ([Ca2+]i) plateau of 155 +/- 50 and 318 +/- 114 nmol/l, respectively. Basal influx was reduced to 88 +/- 8 and 145 +/- 17 nmol/l [Ca2+]i (1-10 mmol/l Ca2+, p < 0.01) by 30 mmol/l D-glucose. This effect of HG was confirmed by Mn2+ quenching of fura-2, indicating reduced entry of divalent cations via the capacitative pathway. Equimolar L-glucose had no effect on Ca2+ influx, consistent with a non-osmotic mechanism. Arginine vasopressin (10 mumol/l) elicited weaker release of stored Ca2+ and subsequent influx in HG cells (191 +/- 33 vs 153 +/- 24 nmol/l, 400 +/- 76 vs 260 +/- 33 nmol/l, 1-10 mmol/l Ca2+, NG/HG, p < 0.05). To examine the involvement of PKC in the effect of HG on capacitative Ca2+ influx, the enzyme was activated or downregulated by treatment with 0.1 mumol/l phorbol myristate acetate (PMA) for 3 min or 24 h, respectively. PMA acutely inhibited Ca2+ influx in NG cells, while PKC downregulation restored it in HG cells. Similarly, the PKC inhibitors staurosporin or H-7 normalized SOC activity in HG cells. In summary, impairment of Ca2+ influx via SOC by HG is one mechanism of the reduced MC [Ca2+]i responsiveness to vasoconstrictors. This event is mediated by PKC and may contribute to the glomerular haemodynamic changes in the initial stages of diabetes mellitus.

Animals↗
PubMed1997

High glucose level unmasks a genetic predisposition to enhanced extracellular matrix production in mesangial cells from the Milan normotensive strain.

A growing body of evidence indicates that the individual genetic background plays a role in the pathogenesis of diabetic glomerular disease by either favoring or protecting against injury produced by hyperglycemia. Two genetically related rat strains, the Milan normotensive strain (MNS) and the Milan hypertensive strain (MHS) display different susceptibilities to develop glomerulosclerosis with age. Glomerular sclerosing lesions occur in the MNS rats, which remain normotensive throughout their entire life-span, but not in the MHS rats, despite the presence of arterial hypertension. Previous studies have reported that extracellular matrix production and cell proliferation increased with donor-aging in mesangial cells isolated from MNS rats, but not in those from MHS rats, thus suggesting the existence of an inherited defect in the regulation of cell and matrix turnover, which translates into an abnormal response to growth-promoting stimuli favoring the development of glomerulosclerosis. In the study presented here, it was hypothesized that, in addition to donor-aging, other independent risk factors for the development of glomerular disease, such as metabolic injury by hyperglycemia, would be able to trigger and/or precipitate the occurrence of these changes in mesangial cells from the susceptible normotensive strain, but not in those from the protected hypertensive strain. To test this hypothesis, mesangial cells obtained from these rat strains (before the onset of either glomerulosclerosis or hypertension) were used to assess the effects of prolonged (4 wk) exposure to high (30 mmol/L) versus normal (5.5 mmol/L) glucose concentrations on extracellular matrix and cytokine production and cell proliferation. The accumulation and/or gene expression of the matrix components fibronectin, laminin, and collagen IV, and of the cytokines insulin-like growth factor-I (IGF-I) and transforming growth factor-beta (TGF-beta) did not change under normal glucose and increased progressively in response to high glucose in both MNS and MHS cells. These increases, with the exception of the increment in TGF-beta gene expression, were significantly more pronounced in MNS cells than in MHS cells. In contrast, the proliferative response to serum was not affected by high glucose, but increased in MNS cells, and decreased, although not significantly, in MHS cells during the 4-wk period, thus mimicking the changes previously observed in these rat strains as a function of age. These results indicate that high glucose unmasks a genetic tendency to produce increasing amounts of extracellular matrix, not yet evident under normal glucose conditions, and suggest that a genetically determined propensity of mesangial cells to hyperrespond to chronic hyperglycemia may be implicated in the pathogenesis of diabetic glomerular disease.

Animals↗
PubMed1997

Upregulation of mesangial growth factor and extracellular matrix synthesis by advanced glycation end products via a receptor-mediated mechanism.

Enhanced advanced glycosylation end product (AGE) formation has been shown to participate in the pathogenesis of diabetes-induced glomerular injury by mediating the increased extracellular matrix (ECM) deposition and altered cell growth and turnover leading to mesangial expansion. These effects could be exerted via an AGE-receptor-mediated upregulation of growth factors, such as the IGFs and transforming growth factor-beta (TGF-beta). We tested this hypothesis in human and rat mesangial cells grown on nonglycated or native bovine serum albumin (BSA), glycated BSA with AGE formation (BSA-AGE), or glycated BSA in which AGE formation was prevented by the use of aminoguanidine (BSA-AM), in the presence or absence of an antibody, alpha-p60, directed against the p60/OST protein named AGE-receptor 1 (AGE-R1), or normal control (pre-immune) serum. The mRNA and/or protein levels of IGF-I, IGF-II, IGF receptors, IGF binding proteins (IGFBPs), TGF-beta1 and the ECM components fibronectin, laminin, and collagen IV were measured, together with cell proliferation. Both human and rat mesangial cells grown on BSA-AGE showed increased IGF-I and total and bioactive TGF-beta medium levels and enhanced IGF-I, IGF-II, and TGF-beta1 gene expression, compared with cells grown on BSA, whereas total IGFBP and IGFBP-3 medium content, IGF receptor density and affinity, and IGF-I receptor transcripts were unchanged. Moreover, cells grown on BSA-AGE showed increased ECM protein and mRNA levels versus cells cultured on BSA, whereas cell proliferation was unchanged in human mesangial cells and slightly reduced in rat mesangial cells. Growing cells on BSA-AM did not affect any of the measured parameters. Co-incubation of BSA-AGE with anti-AGE-R1, but not with pre-immune serum, prevented AGE-induced increases in IGF-I, TGF-beta1, and ECM production or gene expression; anti-AGE-R1 also reduced growth factor and matrix synthesis in cells grown on BSA. These results demonstrate that mesangial IGF and TGF-beta1 synthesis is upregulated by AGE-modified proteins through an AGE-receptor-mediated mechanism. The parallelism with increased ECM production raises the speculation that the enhanced synthesis of these growth factors resulting from advanced nonenzymatic glycation participates in the pathogenesis of hyperglycemia-induced mesangial expansion.

Animals↗
PubMed1997

Early, but not advanced, glomerulopathy is reversed by pancreatic islet transplants in experimental diabetic rats: correlation with glomerular extracellular matrix mRNA levels.

In this study, we investigated 1) whether long-term restoration of euglycemia by means of pancreatic islet transplants is capable of preventing and/or reversing renal functional and structural alterations in an experimental model of insulin-deficient diabetes, and 2) whether changes in extracellular matrix (ECM) and cell turnover at the glomerular level and biochemical abnormalities associated with hyperglycemia correlate with the renal outcome after transplantation. Male Lewis rats, rendered diabetic by intravenous injection of streptozotocin, underwent homologous islet transplantation via the portal vein at 2 weeks (study A), at 4 months (study B), and at 8 months (study C) after the induction of diabetes and killed 12 months after transplantation in study A and 4 months after transplantation in studies B and C. Age-matched nondiabetic and untreated diabetic rats were used as control animals and were studied at 4, 8, and 12 months. In the untreated diabetic animals, metabolic derangement was associated with increased erythrocyte polyol and fructose levels, tail-tendon content of advanced glycation end products (AGEs), total proteinuria, albuminuria, kidney weight, and mean glomerular volume as well as with marked glomerular and extraglomerular lesions. Glomerular gene expression for the ECM components fibronectin and collagen IV and for TGF-beta was also increased, whereas glomerular cell proliferation was unaffected by diabetes. In study A, changes in renal function and structure observed in diabetic rats at 12 months were completely prevented by successful islet transplants. In study B, all functional and structural abnormalities detected in diabetic rats at 4 months of disease duration were virtually reversed by 4 months of euglycemia in transplanted animals, whereas they progressed further in untreated diabetic rats. In study C, the course of functional and structural changes observed in untreated diabetic rats was not reversed by islet transplantation. Likewise, tissue AGE accumulation and particularly upregulation of glomerular ECM and transforming growth factor (TGF)-beta gene expression, which are believed to play a role in the pathogenesis of altered renal function and structure in diabetes, were normalized in transplanted rats from study A and study B, but not in those from study C. These experiments show that restoration of euglycemia by islet transplants is capable of preventing experimental diabetic glomerulopathy and reversing early changes in renal function and structure induced by diabetes. In a later phase of the disease, when glomerular matrix gene expression becomes independent of hyperglycemia, possibly because of the persistent increase in tissue AGE accumulation, metabolic control is not capable of reversing renal abnormalities.

Animals↗
PubMed1997

[Recurring duodenal ulcer. Evaluation of previous complications as a predictive factor of ulcer recurrence after eradication of Helicobacter pylori].

Duodenal ulcer is a chronic disease, punctuated by acute relapses. The pathogenic mechanism in 90-100% of cases is infection by Helicobacter pylori. Two major strains exist of this bacterium: I strain, which secretes a vacuolating cytotoxin (Vac-A), and another protein named cytotoxin-associated (Cag-A) and type II strain, unable to produce both proteins and unable to produce duodenal pathology. We sought to identify the natural history of relapsing duodenal ulcer after cure of the bacterial infection. In particular, we followed the outcome of patients who repeatedly had bled from their recurrent ulcer disease, after success in eliminating the microorganism from the stomach. None of 12 repeated bleeders had an ulcer recurrence after the cure of Helicobacter pylori infection. Only 3 (5%) of 60 frequent relapser had a new episode of duodenal ulcer during a follow-up reinfection by Helicobacter pylori. We demonstrated that the cure of bacterial infection is also the cure of duodenal ulcer recurrence, but for a few cases, in the latter, event one could hypothesize a defect in the production of growth factors (Epidermal Growth Factor, Fibroblast Growth Factor) or of cellular polyamines synthesis. It is important to improve the diagnosis of reinfection by implementing the urea breath test.

English Abstract↗
PubMed1996

Regulatory role of eicosanoids in extracellular matrix overproduction induced by long-term exposure to high glucose in cultured rat mesangial cells.

Accumulation of extracellular matrix in the mesangium and altered renal eicosanoid synthesis are two prominent features of diabetic glomerular disease. We investigated the relationship between eicosanoid and extracellular matrix production in rat mesangial cells cultured under high glucose vs normal glucose conditions. Long-term exposure of rat mesangial cells to high glucose, but not to iso-osmolar mannitol, significantly increased extracellular matrix accumulation and gene expression and transforming growth factor-beta (TGF-beta) mRNA levels, and decreased prostaglandin (PG) E2 synthesis without affecting production of either thromboxane (TX) B2 or PGF2 alpha, with respect to cells incubated in normal glucose. Addition of exogenous PGE2 resulted in a dose-dependent reduction of matrix protein and mRNA levels and TGF-beta gene expression in cells cultured in either normal or high glucose conditions, whereas exposure to exogenous PGF2 alpha produced a significant increment in matrix production and matrix and TGF-beta gene expression in cells grown in normal glucose, but only a slight increase in those cultured in high glucose. Stimulation of endogenous endoperoxide metabolism towards PGE2 and PGF2 alpha synthesis with FCE-22,178, a drug originally developed as TXA2 synthase inhibitor, resulted in a dose-dependent decrease in matrix accumulation and matrix and TGF-beta gene expression which was suppressed by coincubation with the cyclo-oxygenase inhibitor fenoprofen blocking the FCE-22,178-enhanced PG production. In both cell lines, the rate of synthesis of TXA2 was very low and the selective blockade of its synthesis (by two other TXA2 synthase inhibitors, OKY-046 and Ridogrel) or action (by the TXA2 receptor antagonist BM-13,177) did not alter matrix production or TGF-beta mRNA levels. These results suggest that the cyclo-oxygenase pathway is involved in the regulation of matrix changes induced by high glucose in rat mesangial cells; the reduced production of PGE2 may enhance the synthesis or potentiate the effect of stimulators of ECM formation such as TGF-beta, whereas TXA2 does not appear to be involved. These data also indicate that glucose-enhanced mesangial matrix accumulation may be prevented by exogenous PGE2 or by drugs capable of increasing endogenous PGE2 synthesis.

Animals↗
PubMed1996

Increased activity of the insulin-like growth factor system in mesangial cells cultured in high glucose conditions. Relation to glucose-enhanced extracellular matrix production.

Recent evidence suggests that several growth factors participate in diabetic glomerular disease by mediating increased extracellular matrix accumulation and altered cell growth and turnover leading to mesangial expansion. Transforming growth factor (TGF)-beta has been demonstrated to be upregulated both in vivo and in vitro, whereas studies on the activity of the renal insulin-like growth factor (IGF) system in experimental diabetes have provided conflicting results. We investigated the effects of prolonged exposure (4 weeks) of cultured human and rat mesangial cells to high (30 mmol/l) glucose vs iso-osmolar mannitol or normal (5.5 mmol/l) glucose levels on: 1) the autocrine/paracrine activity of the IGF system (as assessed by measuring IGF-I and II, IGF-I and II receptors, and IGF binding proteins); and, in parallel, on 2) TGF-beta 1 gene expression; 3) matrix production; and 4) cell proliferation. High glucose levels progressively increased the medium content of IGF-I and the mRNA levels for IGF-I and IGF-II, increased IGF-I and IGF-II binding and IGF-I receptor gene expression, and reduced IGF binding protein production. TGF-beta 1 transcripts and matrix accumulation and gene expression were increased in parallel, whereas cell proliferation was reduced. Iso-osmolar mannitol did not affect any of the above parameters. These experiments demonstrated that high glucose levels induce enhanced mesangial IGF activity, together with enhanced TGF-beta 1 gene expression, increased matrix production, and reduced cell proliferation. It is possible that IGFs participate in mediating diabetes-induced changes in matrix turnover leading to mesangial expansion, by acting in a paracrine/autocrine fashion within the glomerulus.

Animals↗