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Biomedical subjects

G Gambaro

Publications and source records attributed to G Gambaro.

At least 73 records · Page 4Linked to original sources
PubMed1994

Relationship between membrane protein phosphorylation and intracellular translocation of casein kinase in human erythrocytes.

The present paper shows that an increased phosphorylation of the membrane proteins, promoted by the okadaic acid (strong inhibitor of P-Ser/Thr-protein phosphatase(s)), is accompanied by a release of casein kinase from the membrane into cytosol. Such an intracellular translocation might provide a feedback mechanism for the regulation of the casein kinase catalyzed phosphorylation of membrane proteins in the human erythrocytes.

Adenosine Triphosphate↗
PubMed1994

Capillary zone electrophoresis determination of phenylalanine in serum: a rapid, inexpensive and simple method for the diagnosis of phenylketonuria.

A simple, rapid, and quantitative capillary zone electrophoresis method for phenylalanine analysis in serum has been developed, with the aim of providing an analytical tool, as an alternative to liquid and gas chromatography, for the routine laboratory diagnosis of phenylketonuria. Electrophoresis was carried out in a 65 cm long, 50 microns wide bare silica capillary, using 0.025 M borate (adjusted to pH 10 with 1 M NaOH) at a potential of 20 kV, with in-column UV detection at 214 nm. Under these conditions, the three aromatic amino acids (tryptophan, phenylalanine and tyrosine) migrated according to the pKs of the respective amine (and hydroxyl) groups. The efficiency of separation was about 150,000 plates/column for phenylalanine. Diprophylline was adopted as internal standard. The injection of ethanol-deproteinized normal control serum gave rise to only a few major peaks not interfering with phenylalanine; phenylalanine in serum at normal concentrations appeared in a clean region of the electropherogram as a symmetrical peak with a migration time of about 11 min. The sensitivity was > or = 3 micrograms/mL, with s/n ratio = 3. The linearity, in the range of 5-175 micrograms/mL, was described by the equation y = 1.407-0.583 x, r2 = 0.9998. Accuracy and precision were satisfactory, with intra-day and inter-day coefficients of variation lower than 4% and 7%, respectively. The injection of sera from five phenylketonuria patients gave electropherograms clearly showing huge peaks of phenylalanine, thus allowing an easy laboratory diagnosis of phenylketonuria.

Capillary Action↗
PubMed1994

Effect of alkaline citrate therapy on clearance of residual renal stone fragments after extracorporeal shock wave lithotripsy in sterile calcium and infection nephrolithiasis patients.

The natural history of post-extracorporeal shock wave lithotripsy residual stone fragments (clearance, growth and aggregation) is incompletely known, even though they are believed to constitute a risk in terms of new stone formation and persistent infection of the urinary tract. We addressed this issue and the hypothesis that alkaline citrate therapy improves residual stone fragment clearance in a 12-month followup study. There were 40 sterile calcium and 30 struvite stone patients with residual fragments after extracorporeal shock wave lithotripsy (diameter less than 5 mm.) consecutively enrolled and randomly assigned to a citrate therapy (6 to 8 gm. per day) or control (hygienic measures only) group. Infection stone patients also received adequate antibiotic therapy throughout the study. Among the patients in the untreated sterile group 21% and 32% were stone-free at 6 and 12 months, respectively. In the infection group these figures were 27% and 40%, respectively. Among the untreated sterile calcium stone patients in whom clearance was not achieved a high percentage experienced residual fragment growth or reaggregation. Citrate therapy significantly improved the stone clearance rate in the sterile (at 6 and 12 months 65% and 74% were stone-free, respectively) and infection (71% and 86%, respectively) stone patients, and prevented residual fragment growth or reaggregation in subjects in whom clearance was not achieved. The data show that growth and persistence are common in the natural history of residual stone fragments. Citrate ameliorated the outcome of these residual fragments by reducing the growth or agglomeration, and by increasing the clearance rate in calcium oxalate and in infection stone patients.

Adolescent↗
PubMed1994

Treatment with a glycosaminoglycan formulation ameliorates experimental diabetic nephropathy.

Previous studies have indicated that administration of glycosaminoglycans can prevent some of the morphological and physiological alterations which occur in experimental diabetic nephropathy. The aims of this study were to further elucidate the effect of these drugs on glomerular basement membrane permeability by dextran clearance studies, to test the ability of glycosaminoglycans to revert established diabetic nephropathy and to examine the effect of glycosaminoglycans on renal extracellular matrix synthesis. Five groups of Sprague-Dawley rats were studied for 12 months: two control groups (treated or untreated non-diabetic), three streptozotocin diabetic animal groups, two of which received a glycosaminoglycan formulation, one from the induction of diabetes and the other after the fifth month of diabetes. At five months the 35S-sulfate glomerular incorporation, albuminuria, glomerular basement membrane thickness and anionic charge density were determined. At 12 months albuminuria, renal collagen IV and perlecan mRNA levels, anionic and neutral dextran clearances, glomerular basement membrane morphometry, and mesangial cell proliferation were evaluated. We demonstrate that long-term administration of glycosaminoglycans prevents renal morphological and functional alterations in diabetic rats and appears to revert established diabetic renal lesions. Glycosaminoglycan administration modified renal matrix composition by the normalization of collagen gene expression and increasing glomerular 35S-sulfate incorporation.

Animals↗
PubMed1994

Abnormal erythrocyte and renal frusemide-sensitive sodium transport in idiopathic calcium nephrolithiasis.

1. Anomalous transmembrane anion transport has been observed in erythrocytes of patients with idiopathic calcium nephrolithiasis. 2. To verify whether cation transport is also abnormal, we investigated the frusemide-sensitive Na+ efflux from Na(+)-loaded erythrocytes and the natriuretic response to acute intravenous frusemide administration in calcium oxalate renal stone formers. 3. Frusemide administration induced a statistically significant smaller increase in the fractional excretion of Na+ in patients than in control subjects. Abnormal kinetic properties of erythrocyte Na(+)-K(+)-2Cl- cotransport were observed in approximately 60% of stone formers. The Km for Na+ of Na(+)-K(+)-2Cl- co-transport correlated with urinary Ca2+ excretion. 4. The abnormal kinetic properties of Na(+)-K(+)-2Cl- co-transport may be relevant for stone formation, hampering renal Ca2+ reabsorption in the distal nephron and determining critical physicochemical conditions for calcium/oxalate crystallization.

Adult↗
PubMed1994

Time-limited protective effect of inhaled frusemide against aspirin-induced bronchoconstriction in aspirin-sensitive asthmatics.

Inhaled frusemide effectively prevents the bronchial obstructive response to allergens and to a number of nonallergic stimuli. In most of the experimental models in which it has been tested, the protective effect of frusemide has been evaluated for only a short time after administration. In aspirin-sensitive patients, acetylsalicylic acid causes an asthmatic reaction which typically lasts for 2 h or more after exposure. We investigated the presence and duration of the protective effect of inhaled frusemide against the bronchial response to aspirin in sensitive patients, using a specific inhalation challenge with lysine acetylsalicylate (LASA). In the first study, eight subjects with aspirin-asthma underwent two bronchial challenges with a single dose of lysine acetylsalicylate administered through a jet nebulizer, after treatment with 40 mg inhaled frusemide or placebo, according to a randomized, double-blind protocol. Forced expiratory volume in one second (FEV1) was monitored for 120 min after challenge. In the second study in eight patients, the protocol was modified by the use of a dosimeter for delivery of lysine acetylsalicylate, by reducing the dose of lysine acetylsalicylate to avoid intense reactions, and by extending the follow-up to 4 h. In the first study, after placebo, FEV1 gradually decreased, reaching a maximum decrement of 39 +/- 3% at 120min. Inhaled frusemide exerted a significant protection at all time-points, although this activity appeared to decrease with time. In the second study, after placebo, inhaled lysine acetylsalicylate caused a gradual decrease in FEV1, which reached a maximum decrement at 180 min.(ABSTRACT TRUNCATED AT 250 WORDS)

Administration, Inhalation↗
PubMed1993

Functional correlation between the Ser/Thr-phosphorylation of band-3 and band-3-mediated transmembrane anion transport in human erythrocytes.

In human erythrocytes, okadaic acid, a potent inhibitor of certain protein phosphatases, promotes a marked increase of Ser/Thr-phosphorylation of membrane proteins, including band-3 protein. Moreover, okadaic acid also increases the band-3-mediated oxalate transport across the membranes, thus suggesting that this process is regulated by Ser/Thr-phosphorylation of transporter band-3 protein.

Anion Exchange Protein 1, Erythrocyte↗
PubMed1993

Effects of 1,25-dihydroxyvitamin D3 and growth hormone therapy on serum osteocalcin levels in children with growth hormone deficiency.

In order to investigate the influence on bone metabolism of growth hormone (GH), we evaluated the response to an acute load of 1,25(OH)2D3 (Rocaltrol) (1.5 micrograms/day for 4 days) in 16 growth hormone-deficient prepubertal children (11 boys and 5 girls, aged from 6.2 to 9.6 years) both before and after 1 month of human GH (hGH) therapy (0.1 IU/kg/day, 6 times per week). Before and after the 1,25(OH)2D3 load, serum IGF-I, osteocalcin, Ca, P, alkaline phosphatase (ALP) and urinary excretion of Ca and P were measured. The serum levels of osteocalcin rose significantly after the first 1,25(OH)2D3 load, without an increase in IGF-I values and with a slight non-significant increase in serum Ca and P. Almost superimposable increases of osteocalcin, Ca and P were observed after 1 month of hGH therapy, with a significant increase of IGF-I, but they did not rise further after the second 1,25(OH)2D3 load. On the basis of our results, 1,25(OH)2D3 seems to have a stimulatory action on osteoblastic activity even in the absence of normal levels of GH. However, there is no apparent additional stimulatory activity after administration of hGH. Osteocalcin level behaviour during our study might suggest that GH and 1,25(OH)2D3 have a common and easily saturable stimulatory pathway on osteoblastic function.

Alkaline Phosphatase↗
PubMed1993

Abnormal urate transport in erythrocytes of patients with idiopathic calcium nephrolithiasis: a possible link with hyperuricosuria.

1. The demonstration of an inheritable anomaly of erythrocyte oxalate transport in 'primary' calcium nephrolithiasis suggested that this disease might be a generalized metabolic disorder characterized by a defect in cellular anion transport. 2. To determine whether this anomaly is restricted to oxalate alone, we studied erythrocyte transmembrane urate self-exchange in calcium-oxalate renal stone formers in whom urinary excretion of uric acid is frequently increased. 3. Abnormal urate self-exchange was found in 30% of the patients. The urate self-exchange rate constant was correlated with 24 h urinary excretion of uric acid; the erythrocyte anomaly was also associated with the frequency of hyperuricosuria and a more intense disease activity. Transmembrane urate self-exchange was inhibited by stilbene and heparan sulphate. Morphazinamide administration did not reduce urinary urate excretion in patients with abnormal urate erythrocyte self-exchange. 4. These findings suggest that hyperuricosuria during calcium-oxalate renal stone disease might be due to a cellular defect in urate transport, and further support the hypothesis that idiopathic nephrolithiasis is a metabolic disorder characterized by a defect in cellular anion transport.

Biological Transport↗
PubMed1993

Influence of dietary taurine on vitamin D absorption.

To evaluate the influence of dietary taurine supplementation on vitamin D absorption, we studied three groups of infants: 21 (11 preterm) were fed a taurine-free formula, 21 (10 preterm) were fed a taurine-supplemented formula (50 mg/100 g of powder) and 20 (9 preterm) were fed human, not heat-treated milk. Taurine, total bile acids, glyco-(GBA) and tauro-(TBA) conjugated bile acids, 25-hydroxyvitamin D3 (25OHD3) and 1,25-dihydroxyvitamin D3 (1,25OH2D3) were determined in all infants at birth in blood cord and at one and three months of life. In preterm infants fed a taurine-free formula, we found lower plasma taurine levels than in infants of other groups at one and three months of life. In these infants, GBA predominated, with a G/T ratio of 1.1 and 1.4 at one and three months of life, whereas in all other infants TBA predominated with a G/T ratio always < 1. Also, 25OHD3 and 1,25OH2D3 levels were significantly lower in preterm infants fed a taurine-free formula than in infants fed a taurine-enriched formula or human milk. Term infants fed a taurine-free formula did not show differences in the parameters studied in comparison to infants of other groups. Low taurine dietary intake appears to compromise vitamin D absorption in preterm infants, and therefore taurine supplementation of preterm infant formulas should be encouraged.

Bile Acids and Salts↗
PubMed1993

Evidence of a link between erythrocyte band 3 phosphorylation and anion transport in patients with 'idiopathic' calcium oxalate nephrolithiasis.

This study was carried out to verify the hypothesis of a link between faster endogenous phosphorylation of band 3 protein, the anion carrier, and anomalous oxalate transmembrane self-exchange found in erythrocyte from calcium oxalate renal stone formers. Agents able to modify 32P-labelling of band 3 protein induced a concurrent modification in oxalate transmembrane flux. Cyclic AMP- and phospholipid-sensitive Ca(2+)-independent protein kinases seem to be critical modulators of band 3 function. These observations demonstrate a close link between the band 3 phosphorylation state and its anion transport function, and provide new insights into the pathogenetic mechanisms of the cellular anomalies observed in calcium-oxalate renal stone disease.

Anion Exchange Protein 1, Erythrocyte↗
PubMed1992

Glycosaminoglycans prevent morphological renal alterations and albuminuria in diabetic rats.

Abnormal glycosaminoglycan metabolism is involved in the onset of anatomo-functional derangements in diabetic nephropathy, and determines the loss of glomerular basement membrane anionic charges leading to albuminuria. Glycosaminoglycan administration was shown to increase the negative electrical potential of the vessel wall, inhibit mesangial cell proliferation, which is an anatomical hallmark of diabetic nephropathy, and slow down the progression to uremia in subtotally nephrectomized rats, a model that shares some pathogenetic key events with diabetic nephropathy. Based on these considerations, we verified the effect of exogenous glycosaminoglycans on renal involvement in streptozotocin diabetic rats. Long-term administration of two glycosaminoglycans (low-molecular weight heparin and dermatan sulphate) prevented glomerular basement membrane thickening, glomerular anionic charge reduction, as well as the onset of albuminuria without affecting glomerular filtration rate and metabolic control of the disease. Our data demonstrate that the long-term administration of glycosaminoglycans has a favorable effect on morphological and functional renal abnormalities in diabetic rats.

Albuminuria↗