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Biomedical subjects

G Capasso

Publications and source records attributed to G Capasso.

175 records · Page 10Linked to original sources
PubMedDate not supplied

[The importance of intracellular pH in the regulation of cell function].

Cell life is possible only if intracellular pH (pHi) oscillations are kept within a very narrow range. Measurement of pHi is therefore a very important parameter when examining cell and organ functions. Several methods have been used to monitor pHi; these include fluorescent dyes and pH sensitive electrodes. In addition, many instruments have been applied to the detection of pHi in living organs even at the level of single cells: NMR and confocal microscopy are just an example. Transport proteins located on the cell membrane and intracellular vesicles are responsible for maintaining the correct pHi. In renal tubular cells these include the sodium hydrogen exchanger (NHE), the sodium-dependent and independent chloride-bicarbonate exchanger (Cl--HCO3-), the sodium bicarbonate co-transport (Na+-HCO3-), the ATP-coupled proton pump (H+-ATPasi) and the ATP-dependent proton-potassium pump (H+-K+-ATPasi). All these carriers have been cloned and it is now clear that there are several isoforms with specific properties. The function of these proteins is closely linked to several hormone blood levels, systemic acid-base status, protein diet content as well as other factors. In addition, these carriers are not homogeneously distributed along the nephron and are sensitive to specific stimuli like interstitial osmolality and luminal fluid flow rate. Finally, it has been recently demonstrated that the pHi may be involved in numerous aspects of cell function, such as metabolism, apoptosis, malignancy and it is implicated in the pathogenesis of particular forms of renal stones (Dent's disease).

Angiotensin II↗
PubMedDate not supplied

[New concepts of tubular calcium transport in the kidney: clinical implications].

The kidney plays an important role in calcium homeostasis. In this review we discuss new concepts in tubular calcium transport, related proteins and the clinical implications of these new findings. Most calcium reabsorption occurs in the proximal tubules via the passive paracellular pathway, but calcium reabsorption also occurs in the thick ascending limb of Henle's loop (50% via the transcellular pathway). Finally, at the level of the distal convoluted tubule and connecting tubule calcium is reabsorbed via the active transcellular route. The Calcium-sensing receptor, localised along the thick ascending limb of Henle's loop, regulates the urinary calcium excretion in response to changes in extracellular calcium concentration. The Epithelial Calcium Channel 1 is a highly Ca2+-sensitive channel that is predominantly present in the connecting tubule. The Calbindin D(28k) is a cytoplasmatic protein expressed in the distal tubule, it is involved both in transcellular calcium diffusion and in the control of intracellular calcium concentration. Heterozygous mutations in the gene for the calcium sensing receptor, which result in a loss of function by the receptor, are associated with familial hypocalciuric hypercalcaemia. Mutations involving a gain of function have been associated with hypocalcaemia with normal serum parathyroid hormone concentration. Bartter's syndrome, caused by a dysfunction of thick ascending limb cells, is associated with calcium wasting. On the contrary, Gitelman's syndrome, caused by a dysfunction of the distal tubule, is characterised by hypocalciuria and hypomagnesemia.

Animals↗
PubMedDate not supplied

[Tubolopaties associated to hypokalemia].

We have described two clinical cases of two young men affected by hypkalemia associated with metabolic alkalosis. The first patient also presented hypercalciucia, normal magnesemia, defect in renal concentrating ability and increased renin activity; in addition he was affected by congenital sensorineural deafness. The diagnosis of Bartter's syndrome was made and it was confirmed by the gene analysis, which revealed a mutation for the beta-subunit of the ClC chloride channels known as barttin. The second case was characterized by hypocalciuria and hypomagnesemia, polyuria and nicturia. The genetic analysis revealed a mutation for the gene encoding the Na+-Cl(-) cotransporter and the diagnosis of Gitelman's syndrome was formulated. We present experimental and clinical evidence to explain, at the molecular level, the differences in calcium and magnesium homeostatis in the two cases. Moreover, we propose different causes to justify the pathogenesis of hypokalemia and the related metabolic alkalosis.

Adult↗
PubMedDate not supplied

Achilles tendon rupture in athletes: histochemistry of the triceps surae muscle.

Bilateral percutaneous muscle biopsies of the triceps surae were analyzed in 12 athletes who had sustained a one-sided subcutaneous rupture of the Achilles tendon while practicing their main sport. No necrosis, atrophy, or significant fiber grouping or regeneration was evident. The soleus muscle in these athletes was composed of approximately 70% of type I fibers in both the noninjured and injured sides, and no significant differences were detected in their histochemical composition. Fiber areas were within described values and not significantly different between the two sides. The noninjured side revealed an insignificant trend to greater average capillary density and average capillary/fiber ratio. Muscle abnormalities do not appear to be a significant factor in determining Achilles tendon rupture in healthy athletes.

Achilles Tendon↗
PubMedDate not supplied

Clearance studies on the renal action of porins extracted from Salmonella typhimurium.

The effects of porins on renal hemodynamics and on the renal handling of salt and water were studied in rats. The animals injected with 100 micrograms/kg of porins showed an important change in renal potassium handling. In fact the total potassium excretion decreased significantly (p less than 0.02) from 1.11 +/- 0.13 to 0.495 +/- 0.069 muEq/min/100 g and was significantly associated to a reduction of fractional potassium excretion from 21.6 +/- 4.1% to 12.53 +/- 0.95% (p less than 0.001). It is speculated that porins have the capability to close the potassium channels.

Animals↗
PubMedDate not supplied

IgA glomerulonephritis in Wiskott-Aldrich syndrome.

Renal morphology was evaluated in 2 siblings with Wiskott-Aldrich syndrome (WAS) aged 12 and 4 years. They gave a typical history of recurrent episodes of respiratory infection and presented with microhematuria of glomerular origin and proteinuria. The study disclosed a membranoproliferative glomerulonephritis with IgA mesangial deposition in the elder child, while immunofluorescence was negative in the younger. The data indicate that (1) a specific nephropathy does not exist in WAS and (2) the IgA nephropathy is the result of recurrent infections and of related formation of IgA immune complexes scarcely removed by a deficient reticuloendothelial system. This view is consistent with presenting features in WAS (microhematuria, episodes of macrohematuria, proteinuria, Henoch-Schönlein syndrome) and with the fact that it takes years to develop as indicated by the negativity of immunofluorescence in the younger patient.

Child↗
PubMedDate not supplied

The urinary sodium/potassium ratio in children from southern Italy living in Cimitile: a case for concern.

The urinary sodium/potassium (Na/K) ratio was evaluated in 220 children aged 3-16 years living in Cimitile, a small town near Naples in Southern Italy by utilizing 24 hour urinary collections. The Na/K ratio averaged 3.79 +/- 1.68 and correlated significantly (p less than 0.001) with age, body weight and height but not with Body Mass Index (BMI). No difference was seen when data were analyzed by sex. Mean daily sodium excretion averaged 3.91 +/- 1.52 mM/Kg while potassium excretion averaged 1.17 +/- 0.54 mM.Kg. The Na/K ratio was higher than that observed in children studied in Israel, United Kingdom, USA, and the Federal Republic of Germany and is of the same magnitude of that previously reported in children born in Japan. This high Na/K ratio is a case for concern because of the risks connected with high Na/K ratio in urine.

Adolescent↗
PubMedDate not supplied

Population based data on age related excretion of creatinine sodium and potassium in children of Southern Italy--the Cimitile study.

This is a population based study on urinary excretion of sodium, potassium and creatinine in children from Southern Italy aged 3-16 years. Mean urinary creatinine excretion was 33 +/- 10 mg/kg. Mean sodium excretion was of 3.91 +/- 1.52 mM/kg. Urinary sodium, potassium and creatinine correlated with age, body weight, body mass index (BMI) and height and no difference was found in the comparison among sexes. The data point to an excessive sodium intake in these children and additionally claim for a reconsideration of urinary creatinine excretion in this age group.

Adolescent↗
PubMedDate not supplied

Acute renal failure due to cisplatin.

A case of acute renal failure associated with cisplatin therapy for a stage IV neuroepitelioma of the chest wall is described. This case was associated with a normal magnesium concentration and with presence of fibrinogen in the Tubular Basement Membrane and of IgG in the interstitial infiltrates. Immunological activation was evidentiated by fine needle aspiration biopsy (FNAB) at the time of renal biopsy.

Acute Kidney Injury↗
PubMedDate not supplied

The Italian Registry of Pediatric Chronic Peritoneal Dialysis: a ten-year experience with chronic peritoneal dialysis catheters.

OBJECTIVE: To analyze the data from 347 peritoneal catheters implanted in 249 pediatric patients aged < or = 15 years at start of chronic peritoneal dialysis (CPD). DESIGN: Restrospective study of the data collected between 1986 and 1995, in 20 dialysis centers, from the Italian Registry of Pediatric Chronic Peritoneal Dialysis. Data collection for each pediatric catheter included: catheter type, site and technique of insertion, complications, duration, and reason for removal or replacement. RESULTS: Fifty catheters were inserted in patients under 2 years of age, 50 in patients aged 2 - 5 years and 247 in patients over 5 years of age. Catheter types included 307 (88.5%) Tenckhoff (286 double cuff, 21 single cuff) and 40 (11.5%), double-cuff, Valli-type catheters. All catheters were surgically implanted and omentectomy was performed in 83.5% of cases; the entry-site was in the midline in 136 cases (39.2%) and paramedian in 211 (60.8%). During 6076 CPD months we observed 274 catheter-related complications: 182 catheter infections (exit-site and/or tunnel infection), 23 leakages, 19 obstructions, 19 cuff-extrusions, 14 dislocations, 6 hemoperitoneum, 10 other (incidence of one complication every 21.8 dialysis-months). A significant reduction of catheter-related complications occurred in the last five years, compared with the first 5 years. One hundred and six catheters were removed due to catheter-related causes: infection (83 cases), obstruction (11), dislocation (4), outer-cuff extrusion (3), leakage (2), bowel incarceration (2), and bowel infarction (1). Catheter survival was 72.2% at 12 months, 52.3% at 24 months, 32.8% at 36 months, and 25.7% at 48 months. Significantly lower catheter survival was found in younger children (0 - 2 years) compared with two other age groups (2 - 5 years, and > 5 years). No significant correlation was found between catheter survival and catheter entry-site (midline vs paramedian). CONCLUSIONS: Catheter-related infections were confirmed to be the most common complication and most frequent cause of peritoneal catheter removal. In addition, catheter survival rate was worse in younger children, indicating that more effort should be made to improve peritoneal catheter survival particularly in this age group.

Adolescent↗