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G Piccoli

Publications and source records attributed to G Piccoli.

At least 91 records · Page 5Linked to original sources
PubMed1994

High resolution of multiple forms of rabbit reticulocyte hexokinase type I by hydrophobic interaction chromatography.

Hydrophobic interaction chromatography (HIC) has been employed extensively in the separation of proteins by elution using a descending salt gradient, with and without the use of detergents or denaturing agents. In this study, a new hydrophobic interaction chromatographic support, Toyopearl Phenyl 650 S, was investigated in order to examine the distribution of multiple forms of rabbit reticulocyte hexokinase type I. These distinct forms of the enzyme, designated hexokinase Ia, Ia* and Ib, show similar kinetic and physical properties, similar molecular masses (ca. 100,000) and a different intracellular distribution. The results obtained using Toyopearl Phenyl 650 S of 20-50-microns particle diameter show that this HIC support allows very high resolution, comparable to that obtainable with HIC-HPLC columns but with the advantage of charging a higher amount of starting material even with a high protein concentration. These characteristics render Toyopearl Phenyl 650 S suitable for analytical and preparative purposes. Further, in the separation of multiple forms of rabbit reticulocyte hexokinase, the HIC method was shown to be superior to RP-HPLC, making possible the efficient separation of proteins with high molecular mass and their recovery in active forms. The Toyopearl Phenyl 650 S column was also shown to be more efficient than the ion-exchange chromatographic media previously used, allowing a quicker analysis of the multiple forms of rabbit reticulocyte hexokinase under different biological conditions.

Ammonium Sulfate↗
PubMed1994

Simultaneous high-performance capillary electrophoretic determination of reduced and oxidized glutathione in red blood cells in the femtomole range.

This paper describes a high-performance capillary electrophoretic (HPCE) method which allows a quick, simultaneous and quantitative determination of reduced (GSH) and oxidized (GSSG) glutathione in mammalian red blood cells using a Supelco-bonded hydrophilic phase capillary CElect-P150. The extraction procedure of GSH and GSSG from erythrocytes using Microcon-10 membranes is very simple and allows a correct evaluation of these compounds present in the red blood cells. Furthermore, the HPCE method does not require removal of the excess N-ethylmaleimide used to block the glutathione in its reduced state, making the simultaneous evaluation of GSH and GSSG possible in a very short time (ca. 4 min), with a sensitivity at femtomole level.

Animals↗
PubMed1994

Inactivation of rabbit red blood cell hexokinase activity promoted in vitro by an oxygen-radical-generating system.

Rabbit red blood cell hexokinase (EC 2.7.1.1) has been shown to be inactivated in vitro by incubating intact erythrocytes in the presence of an oxygen-radical-generating system represented by ascorbate and iron. It was interesting to note that among the glycolytic enzymes, only hexokinase was found to be susceptible to the action of oxygen radicals, suggesting that the loss of activity of this enzyme may be one of the first signals of cellular damage in rabbit red blood cells. This statement is supported by the fact that, under the experimental conditions used, we did not observe any significant plasma membrane lipid peroxidation nor intracellular proteolysis. Furthermore, mature erythrocytes are unable to synthesize hexokinase as well as other proteins de novo; therefore, the inactivation of this enzyme, which is both the first and one of the rate-limiting enzymes of the glycolytic pathway, could play an important role in determining metabolic impairment of red blood cells, with possible physiological implications. We also investigated the effect of various radical scavengers and antioxidants (glucose, vitamin E, dithiothreitol, flavonoids) which are able to influence the inactivation of hexokinase activity to different extents. Finally, under the experimental conditions used (90 min of incubation at 37 degrees C), we did not observe any difference in the hemolysis of rabbit red blood cells incubated in the presence or absence of ascorbate and iron (hemolysis was about 1% after 90 min of incubation), suggesting that the system used was able to furnish information about the cellular damage produced by oxygen radicals without provoking cell lysis.

Adenosine Triphosphatases↗
PubMed1994

Functional consequences of the binding of gliadin to cultured rat mesangial cells: bridging immunoglobulin A to cells and modulation of eicosanoid synthesis and altered cytokine production.

Oral immunization with gliadin (GLI) can induce immunoglobulin A mesangial deposits (IgA nephropathy [IgAN]) in mice. A role for GLI in human IgAN has been inferred from an association with celiac disease, increased serum anti-GLI IgA in patients with IgAN, and benefit from a gluten-free diet observed in some IgAN patients. These effects might be due to the antigenic or lectinic properties of GLI. The aim of our study was to investigate whether GLI binding to glycosylated residues (ie, lectinic activity) favors binding of GLI to cultured rat mesangial cells, bridging IgA macromolecules. We also sought to determine whether GLI binding alters mesangial cell function. Gliadin binds to rat mesangial cells in the third and fourth passages, as determined by immunofluorescence. Gliadin binding is inhibited by co-incubation with 1 mol/L N-acetyl-D-glucosamine and 1 mol/L alpha-D-mannose, sugars competitive for this lectinic bond. Quantification by biotinylated GLI revealed a significant dose-dependent binding of GLI (P < 0.001) inhibited by N-acetyl-D-glucosamine (P < 0.05). Some saccharolytic enzymes, like invertase, modify the cell surface to decrease GLI binding (P < 0.02). In addition, GLI promoted the binding of purified mouse polymeric IgA to mesangial cells. The binding of GLI to mesangial cells modulates arachidonic acid metabolism by cultured mesangial cells, significantly inhibiting prostaglandin E2 production (P < 0.02), increasing synthesis of thromboxane B2 (P < 0.01) and tumor necrosis factor (P < 0.001), but not interleukin-1 beta. These responses were abrogated by co-incubation with N-acetyl-D-glucosamine and/or pretreatment with invertase. Non-immune binding of an environmental alimentary lectin, GLI, to mesangial cells in culture might favor the binding of IgA and IgAIC to mesangial cells, enhancing both IgA mesangial trapping and in situ IgA deposit formation. This could occur via GLI-specific antibodies or by virtue of the binding of nonspecific IgA on a lectinic basis, or both. Moreover, related changes in eicosanoid synthesis might stimulate mesangial cell growth and mesangial matrix production, together with mesangial cell contraction, contributing to the pathogenesis of IgAN.

Animals↗
PubMed1994

Cell density-dependent regulation of ATP levels during the growth cycle of cultured Chinese hamster ovary cells.

Chinese hamster ovary (CHO) cells show a cell density-dependent modification of ATP levels during the growth cycle. Cells were seeded at a density of 500,000 cells/75 cm2 flask in 10 ml of growth medium and at various time intervals, samples were taken and assayed for cell number, for adenine (ATP, ADP, AMP) and pyridine (NAD+, NADP+) nucleotide levels and for the activity of some glycolytic enzymes. Glucose consumption was also evaluated. Experimental results indicated that the rate of cell growth was exponential for up to the 4th day of culture after which the cell number remained pratically unchanged up to the 9th day. Under these experimental conditions we found that, whereas the intracellular levels of NAD+ and some glycolytic enzymes were not significantly affected, a drop in ATP content was apparent after 48 hr of culture. The decline in ATP levels progressively increased, reaching a maximum after 4 days of culture, and then remained unchanged. In order to evaluate whether this effect on ATP was determined by a reduced availability of nutritional factors or was really a function of cell density, we also performed experiments similar to those reported above, with the exception that the cells were grown in 40 ml of culture medium. Under these experimental conditions, the exponential growth was longer (in comparison with the cell growth in 10 ml of medium) and a plateau was reached after 6 days of culture.(ABSTRACT TRUNCATED AT 250 WORDS)

Adenine Nucleotides↗
PubMed1994

[Dialysis treatments outside the hospital].

In the early sixties a dramatic lack of hospital dialysis facilities prompted the development of home dialysis programs. The same reasons favoured in Turin, several years later, the start of a home-dialysis program and of the first European self dialysis program in an out-of-hospital setting. In the following years continuous ambulatory peritoneal dialysis was begun. In the last few years we are experiencing a new shortening of in-hospital dialysis facilities; moreover, special attention is devoted to the costs of dialysis treatment, often overlooked in the past. It is likely that self-care and home dialysis will again aid us to solve these problems, as in the past. In this paper we report on the clinical, rehabilitative and socioeconomic results of out-of-hospital dialysis treatments, and on the possible future development of home-hemodialysis and CAPD in Piedmont.

Adult↗
PubMed1994

[Surgical interventions in dialysis patients in Piedmont: data from the Regional Registry. Working Group of the Piedmont Registry of Dialysis and Transplantation].

In this work surgical events in a large population of chronic dialysis patients are analysed. Data are obtained from the Regional (Piedmont) Registry of Dialysis and Transplantation (RPDT), that has collected information since 1981 about all chronic dialysis patients in the Region. Since 1984, causes of admission to-hospital are registered. Surgical causes of hospitalization, for purposes not related to uremia, were 538 (20% of all surgical admissions). In patients younger than 65 years, these hospitalizations account for about 6% of the cases, whereas in patients older than 65 they are less than 5%. As expected, a higher number of surgical operations is observed in diabetics, while on the contrary the lowest is performed in nephroangiosclerosis patients. Cardiovascular and bowel diseases represent almost 50% of all surgical needs. Postoperative mortality was 5.8% within 45 days from admission. Cardiac and infectious diseases and cachexia represent the more frequent causes of death. In 27 out of 28 cases at least one high risk condition was present.

Aged↗
PubMed1994

[Automated peritoneal dialysis (APD). Experience in 42 patients].

Automated peritoneal dialysis (APD) is currently considered as one of the most attractive home treatments for uremic patients. However, relevant costs and the presence of a dialysis machine prevent a wider diffusion of this technique. In this work we discuss the results obtained in 42 patients (12 females, 30 males) treated by two dialysis units of the Piedmont Region. Patients' characteristics. Eighty-three percent of the females and 66.5% of the males are under 65 years of age; glomerulo-nephritis and nephroangiosclerosis account for the most frequent renal diseases (28.5 each); a high risk condition is recorded in 52.5% of cases. Twenty-two patients were transferred to APD from CAPD (patient's request in 59% of cases, clinical problems in the remaining). RESULTS. Forty-five percent of cases are working full or part-time, 12% are not caring for self. Peritonitis rate accounts for 1 episode every 42 patient-months. Biochemical control is satisfactorily achieved (mean values: urea 137.8 mg/dl, creatinine 11 mg/dl, calcium 10.2 mg/dl, phosphate 5.7 mg/dl, albumin 4.3 g/dl, cholesterol 234 mg/dl, triglycerides 195 mg/dl). Technical assistance was requested on average once every 16 months of treatment. CONCLUSION. Negative drawbacks of APD, mainly related to elevated costs and technical complexity, are fully counterbalanced by satisfactory social and clinical rehabilitation, wider indications to peritoneal dialysis with respect to CAPD, lower rates of peritonitis and limited technical needs.

Adult↗
PubMed1994

Urinary endothelin in glomerulonephritis patients with normal renal function.

The vasoconstrictor peptide endothelin-1 (ET1) has only recently been characterized and its effects are at present largely speculative. It has been hypothesized that ET1 acts on mesangial cells to cause vasoactive changes which might ultimately contribute to the development of glomerulosclerosis. Opposite to ET1, nitric oxide (NO) inhibits mesangial cell contraction and proliferation. NO activates soluble guanylic acid cyclase and the final product, cyclic GMP (cGMP), has been recently used as a marker of NO action. Urinary levels of ET1 and cGMP were detected in 58 patients with biopsy-proven glomerulonephritis (GN), including 36 IgA nephropathy (IgAGN), 30 with normal and 6 with impaired renal function, 10 patients with non-IgA mesangial GN and 12 pts with membranous GN (MGN) with normal renal function. Compared to normal controls (0.019 +/- 0.006 ng/min), urine ET1 levels were significantly higher in patients with normal renal function having IgAGN (0.035 +/- 0.017, p < 0.01), MGN (0.028 +/- 0.013, p < 0.05), non-IgA mesangial GN (0.027 +/- 0.012, p < 0.05) and those with IgAGN and renal failure (0.032 +/- 0.011, p < 0.01). However no difference was found between MGN patients and normals by deleting MGN cases with mild to moderate mesangial proliferation. The mean value of urinary cGMP in IgAGN patients with renal failure (0.186 +/- 0.117 nmol/min) was lower (p < 0.05) than that of each group with normal renal function (IgAGN: 0.378 +/- 0.010 nM/min; MGN: 0.338 +/- 0.064 nmol/min, non-IgAGN: 0.436 +/- 0.168 nmol/min). The same significant differences were obtained by correcting cGMP values for creatinine urinary excretion. Urinary ET/cGMP ratio (assumed as an index of the relative balance between vasoconstrictor and vasorelaxing factors) was found to be higher than normal (0.570 +/- 0.010 ng/nmol) both in IgAGN patients with normal renal function (0.103 +/- 0.064 ng/mol, p < 0.05), and in those with renal failure (0.203 +/- 0.108 ng/nmol, p < 0.02). Urinary cGMP values were not related to plasma levels of atrial natriuretic peptide (ANP). These data show that hyperexcretion of ET1 occurs in a number of patients with mesangial proliferative GN. In some of them, mainly those with established glomerular damage, the local production of ET1 is not counter-balanced by adequate cGMP biosynthesis.

Adult↗
PubMed1994

Experimental IgA nephropathy secondary to hepatocellular injury induced by dietary deficiencies and heavy alcohol intake.

BACKGROUND: In humans, alcoholic liver disease is frequently associated with IgA mesangial deposits, microscopic hematuria and a small amount of proteinuria, identifying a secondary form of IgA nephropathy. Alcoholic liver disease is almost always associated with nutritional deficiencies. EXPERIMENTAL DESIGN: In order to examine the relationship between alcohol intake and/or inadequate diet and IgA nephropathy, groups of 4 week-old-male Lewis rats were maintained on a lipotrope-deficient (LD) diet (N = 20), intragastric infusions of a commercial whiskey (1.5 ml/100 gm body weight) three times a week, and regular chow (N = 23) or both intragastric whiskey infusion and an LD diet (N = 17). A fourth control group (N = 19) was given no whiskey and normal chow. RESULTS: All rats given the LD diet had marked steatosis and elevated "liver" enzymes. Changes were more severe, and with early bridging fibrosis and nodule formation in those also given whiskey, associated with increased hepatic content of mRNA encoding transforming growth factor-beta. A moderate steatosis without alteration in serum enzymes or transforming growth factor-beta expression was found in rats given whiskey (all p < 0.0001) compared with controls. IgA accumulated in hepatic sinusoids instead of in canaliculi and bile ducts, suggesting impaired transport of IgA and IgA immune complexes from blood to bile, in rats given an LD diet and/or whiskey infusion. A moderate increase in mesangial matrix was observed only in rats given both whiskey and an LD diet. Bright granular IgA and mild granular C3 mesangial deposits and electron-dense deposits were evident in 63 to 70% of experimental rats (all p < 0.001) versus only trace deposits in 5 to 11% of controls. Moderate IgG codeposits were present in 34 to 55% of rats given the LD diet and/or whiskey (all p < 0.02), versus trace deposits in 10% of controls. Significant hematuria and proteinuria were observed in rats given the LD diet and/or whiskey (p < 0.0001) versus controls. Intestinal permeability measured by xylose absorption was significantly increased relative to controls only in rats given both whiskey and the LD diet (p < 0.001). Serum IgA specific for selected alimentary antigens was increased relative to controls in 75 to 100% of the experimental rats. CONCLUSIONS: The combination of LD diet and alcohol intake, which mimics the human alcoholic condition, promotes hepatic and renal changes, leading to hepatocellular injury and a secondary form of IgA nephropathy.

Alcoholism↗
PubMed1993

Sodium-lithium countertransport activity in red blood cells of patients with IgA nephropathy.

In this paper we report some results of our studies on patients with immunoglobulin (Ig)A nephropathy regarding (1) the familiar aggregation of erythrocyte sodium-lithium (Na,Li) countertransport; (2) the association of Na,Li countertransport with the presence of arterial hypertension and lipid abnormalities; (3) the correlation between Na,Li countertransport activity and renal functional reserve; and (4) the preliminary results of a longitudinal study. In 13 families of patients with IgA nephropathy, selected because both parents were available, we found a significant correlation between midparent and offspring Na,Li countertransport activity (Spearman's rank correlation = 0.65; P = 0.023), but no husband-wife relationship. In 49 patients, the activity of Na,Li countertransport was significantly higher in erythrocytes from 20 hypertensive patients than from either 29 normotensive patients or from 36 healthy age- and sex-matched normal subjects. Hyperlipidemic patients had an erythrocyte Na,Li countertransport activity significantly higher than normolipidemic patients and controls. In 17 patients a significant inverse correlation was found between the peak variation of creatinine clearance over baseline value after an oral protein load and the erythrocyte Na,Li countertransport activity (Spearman r = 0.54; P = 0.03). In a longitudinal study of 36 patients followed from 12 to 36 months, those showing a progression toward renal failure had an erythrocyte Na,Li countertransport activity higher than median value. The results of our studies show that in patients with IgA nephropathy a high erythrocyte Na,Li countertransport rate, genetically determined, is associated with the presence of arterial hypertension and lipid abnormalities, and perhaps with a less favorable disease outcome.

Adolescent↗
PubMed1993

Angiotensin II local hyperreactivity in the progression of IgA nephropathy.

Immunologic and hemodynamic factors are likely to work in synergism in the progression of immunoglobulin A nephropathy (IgAN) toward sclerosis. The local activation of the renin-angiotensin system may be one the most relevant mechanisms. We investigated the hemodynamic effects of the acute administration of angiotensin-converting enzyme inhibitor (ACEI) (captopril 50 mg). The glomerular filtration rate (GFR) and the effective renal plasma flow (ERPF) were measured by 51Cr-EDTA and 125I hippurate clearances. The correspondent filtration fractions (FFs) in basal conditions and after administration of ACEI were calculated, then the changes in FF (delta FF and % delta FF) were determined. We studied 27 IgAN patients. Eighteen patients had normal renal function (GFR, 112 +/- 19 mL/min/1.73 m2) and nine had moderate renal impairment (GFR, 54 +/- 13 mL/min/1.73 m2). Sixteen patients had proteinuria > or = 0.5 g/d. In addition, 12 glomerulonephritis control cases and eight healthy subjects were investigated. After the administration of ACEI in healthy subjects we observed slight modifications in the GFR, a significant increase in the ERPF (P < 0.005), and a significant decrease in FF (P < 0.04). Similarly, in IgAN patients with normal renal function the GFR increased slightly, the ERPF increased significantly (P < 0.01), and there was a decrease in FF (P < 0.01). The delta FF and % delta FF values were not significantly different from those found in the controls. In patients with initial renal failure GFR remained unchanged, ERPF increased significantly (P < 0.005), and FF significantly decreased (P < 0.004). However, the changes in delta FF and % delta FF were significantly greater than those found in healthy controls (P < 0.01) and in IgAN patients with normal renal function (P < 0.001). IgAN patients with proteinuria levels > or = 0.5 g/d showed greater changes in delta FF and % delta FF after the administration of ACEI than patients with proteinuria levels lower than 0.5 g/d (P < 0.003 and P < 0.04, respectively) or proteinuric control cases (P < 0.05 and P < 0.01, respectively). This different response in proteinuric and nonproteinuric patients was evident even when the analysis was limited to the subgroup of IgAN patients with normal renal function. The decrease in FF consequent to an increase in the ERPF after the administration of ACEI suggests a local hyperactivity of the renin-angiotensin system in some cases of IgAN.(ABSTRACT TRUNCATED AT 400 WORDS)

Adult↗
PubMed1993

Role of monocytes in cryoglobulinemia-associated nephritis.

Several monocyte-macrophage functions were found to be defective in cryoglobulinemic patients. Nevertheless, monocytes actively phagocytizing cryoglobulins have been frequently found in kidney specimens from these patients. Whether subsequent degradation of the ingested immune material is effective, however, is still unknown. Monocytes from eight cryoglobulinemic patients (4 with active disease and associated nephritis and 4 inactive cases without nephritis) and eight normal controls of same sex and similar age were analyzed. Monocytes from patients with active cryoglobulinemia and associated nephritis were found to be able to ingest, but unable to catabolize, cryoglobulins, as shown by electron microscopy using gold-labeled goat IgG to human IgG and IgM in 18-hour cultured suspensions. Synthesis and maturation of monocyte cathepsin D, one of the most important lysosomal proteases, were analyzed in the same subjects. Purified monocytes were cultured in presence or absence of cryoglobulins for 18 hours at 37 degrees C in RPMI medium and labeled with 35S-methionine. The various forms of cathepsin D were separated by electrophoresis and visualized by fluorography. Results from cultures of monocytes from clinically active cryoglobulinemic patients with nephritis suggest that intracellular transport of newly synthesized cathepsin D was impaired and the release into the medium of precursor polypeptides of the enzyme enhanced in each experimental condition. Since procathepsin D is susceptible to activation in pathologic conditions lowering local pH (such as in inflamed tissues), these data suggest that monocytes from patients with active cryoglobulinemia and associated nephritis have a propensity to exert phlogistic effects via secretion of procathepsin D in tissues.

Adult↗
PubMed1993

Soluble interleukin-2 receptors and beta 2-microglobulin in patients with primary glomerulonephritis.

Serum levels of soluble interleukin-2 receptors (IL2R) and of beta 2-microglobulin (beta 2M) were studied with the immunoenzymatic technique in 38 patients with primary glomerulonephritis (GN), in 10 patients with essential hypertension (EH) and in 30 healthy subjects. IL2R correlated with beta 2M (p < 0.05). IL2R and beta 2M were higher in patients with GN (p < 0.003, p < 0.001, respectively) and in patients with EH (p < 0.003, p < 0.01, respectively) than in healthy subjects. IL2R and beta 2M correlated with serum creatinine, but not with proteinuria. Our data would suggest the existence of lymphocyte activation in patients with GN. Only speculations can be advanced with regard to the observed increase in these parameters in EH patients.

Adult↗