Characterization of voltage-dependent calcium influx in human erythrocytes by fura-2

Thus far, the methods used to determine erythrocyte Ca2+ influx have not allowed the assessment of the kinetics of ion uptake. To overcome this drawback, we studied a new method, using the fluorescent Ca2+-chelator fura-2, which directly quantifies intracellular Ca2+ changes in human erythrocytes. This method has the advantage over previous techniques that it monitors continuously cellular Ca2+ levels. The Ca2+ influx is modulated by cellular membrane potential in the presence of a transmembrane Ca2+ concentration gradient and exhibits a first slow increase of the intracellular Ca2+ concentration, followed, after the reachment of a threshold value of 125 +/- 13 nM Ca2+, by a faster increase until a plateau is reached. The influx rate is inhibited by dihydropyridines in the micromolar range. These findings support the hypothesis that erythrocyte Ca2+ influx is mediated by a carrier similar to the slow Ca2+ channels and is dependent on membrane depolarization.

Renal genetic mechanisms of essential hypertension

Human essential hypertension is a polygenic disease whose phenotypic expression is modulated by the environment. Though the kidney could play a major role in the initiation and maintainment of hypertension, many questions remain open. Rat models of primary hypertension provided the substantial information with experiments on kidney cross-transplantation showing that at least a portion of hypertension could be transplanted with the kidney in all strains where such experiment has been carried out. Data consistent with those of rats have also been obtained in humans. Many abnormalities in kidney function and cell membrane on transport have been described in hypertensive rats and humans but the logical sequence of events going from a genetic-molecular abnormality to a cellular abnormality which causes hypertension via a modification of kidney function is difficult to prove. We established this sequence in Milan hypertensive rats using a variety of experimental techniques such as the study of isolated kidney and renal cell function, cell membrane ion transport, cross-immunisation with membrane proteins, molecular biology, genetic crosses and manipulation. Such study led to the identification of a polymorphism in the cytoskeletal protein adducin and to the demonstration of its role in blood pressure control. Recently, alpha-adducin variants have been associated to both human primary hypertension and salt sensitive hypertension. Finally, recent findings strongly support the hypothesis that adducin variants may affect kidney function by modulating the overall capacity of the tubular epithelial cells to transport ions through both a modification in the assembly of actin cytoskeleton, and a modulation of sodium pump activity.

[Renal injury in childhood]

The Authors report a case of blunt renal trauma in a nine-year-old boy. Clinical and therapeutic approaches are discussed in the light of a wide review of the literature.

IL-15 is chemotactic for natural killer cells and stimulates their adhesion to vascular endothelium

Interleukin-15 (IL-15) is a recently described cytokine with IL-2-like stimulating activities on T lymphocytes and natural killer (NK) cells. IL-15 mediates its function through the beta- and gamma-chains of the IL-2 receptor. In this work, we have investigated the effect of IL-15 on the directional migration of NK cells in chemotaxis assays and on the ability of NK cells to bind to vascular endothelium. IL-15 (10-20 ng/mL) had chemotactic effects on freshly isolated resting NK cells as well as on long-termed IL-2-cultured NK cells. A checkerboard experiment demonstrated that migration in response to IL-15 was observed only in the presence of a positive gradient (chemotaxis). Overnight treatment of freshly isolated NK cells with IL-15 (10-20 ng/mL) augmented their binding to cultured endothelial cells (EC) in vitro, especially to resting EC. IL-15-activated NK cells bound to resting and tumor necrosis factor-activated EC by use of LFA-1/ICAM-1 and VLA-4/VCAM-1 adhesion pathways, essentially as untreated NK cells do. The fact that IL-15 increased NK cell binding to ICAM-1-transfected NIH-3T3 fibroblasts, together with the finding that IL-15 did not increase binding to extracellular matrix proteins, where the major molecules involved are VLA proteins, indicated that IL-15 primarily stimulates LFA-1-dependent adhesion. By increasing NK cell adhesion to vascular endothelium and migratory response, IL-15 is an important determinant of NK cell recruitment in tissues.

[Aorto-enteric fistula: current information on diagnostic and therapeutic procedures]

The Authors point out how AEFs represent a serious complication of aortic vascular surgery. Special attention is given to the diagnostic and therapeutic approach, also supported by a wide review of the literature.

Clinical implications of GBV-C/HGV infection in patients with "HCV-related" chronic hepatitis

BACKGROUND/AIMS

To evaluate the clinical, biochemical and histological implications of a concomitant HGV infection in "HCV-related" chronic liver disease.

METHODS

Eighty-three HCV-RNA positive patients with chronic liver disease were tested for GBV-C/HGV coinfection by heminested PCR.

RESULTS

Twenty-two (26.5%) patients were found to be positive for GBV-C/HGV RNA. GBV-C/HGV+ patients differed significantly from GBV-C/HGV- ones for younger age, higher frequency of history of drug addiction, which in turn might favor coinfection with interferon-sensitive HCV genotypes (3a), and increased probability of long-term response to interferon. GBV-C/HGV infection appears to have no responsibility for specific aspects of HCV infection such as biochemical or histological cholestatic features, lymphoid follicles, symptomatic cryoglobulinemia or presence of serum autoantibodies, including LKM1. It does not worsen the HCV-related disease (ALT levels and histological activity) and does not significantly interfere with HCV infection, as explored by the number of hepatocytes positive for HCV antigens. The amount of steatosis (mean score) was shown to be higher in GBV-C/HGV+ patients. A virological follow up was performed in 17 interferon-treated GBV-C/HGV+ patients On the whole, GBV-C/HGV seems to be as sensitive to IFN treatment as HCV, but recurrence after withdrawal is more frequent. In spite of this, ALT levels often remain normal after treatment withdrawal.

CONCLUSIONS

The present data suggest that GBV-C/HGV infection, apart from more marked liver steatosis, does not modify the overall picture of chronic hepatitis due to HCV infection.

Polymorphisms of alpha-adducin and salt sensitivity in patients with essential hypertension

BACKGROUND

Abnormalities in renal sodium transport may be involved in hypertension. Adducin, an alpha/beta heterodimeric protein found in the renal tubule is thought to regulate ion transport through changes in the actin cytoskeleton. We investigated whether an alpha-adducin polymorphism (Gly 460 Trp) is involved in essential hypertension in two separate populations.

METHODS

Linkage analysis of three DNA markers at different distances from the alpha-adducin locus (20-2500 kb) was done in 137 hypertensive sibling-pairs. 477 hypertensive and 322 normotensive individuals were genotyped for the alpha-adducin polymorphism. The blood-pressure response to acute and chronic changes in sodium balance was studied in hypertensive individuals with and without the 460 Trp alpha-adducin allele.

FINDINGS

Significant linkage was found for all three markers in the sibling-pair study. The extra shared alleles (9.1%, 6.5%, and 4.7%) and the significance level for linkage (p = 0.0006, p = 0.0119, and p = 0.0211) both decreased with increasing distance from the alpha-adducin locus. There was a significant association between the 460 Trp mutation and hypertension (p = 0.0003). In the salt-sensitivity test, to assess the acute blood-pressure response to changes in body sodium in 86 hypertensive patients, the decrease in mean arterial pressure was greater in 65 patients who were heterozygous for the mutant allele (Gly/Trp) than in 21 wild-type homozygotes (Gly/Gly) (mean decrease 15.9 [SE 2.0] vs 7.4 [1.3] mm Hg; p = 0.001). Similarly, 21 heterozygous hypertensive patients showed a greater fall in mean arterial pressure in response to 2 months' treatment with hydrochlorothiazide than did 37 wild-type homozygous hypertensive patients (mean decrease 14.7 [2.2] vs 6.8 [1.4] mm Hg; p = 0.002).

INTERPRETATION

Our findings of significant linkage of the alpha-adducin locus to essential hypertension and greater sensitivity to changes in sodium balance among patients with the mutant allele suggest that alpha-adducin is associated with a salt-sensitive form of essential hypertension. We suggest the alpha-adducin polymorphism may identify hypertensive patients who will benefit from diuretic treatment or manoeuvres to reduce total body sodium.

[Signet ring cell adenocarcinoma of the colon (signet ring carcinoma): is it really a rare neoplasm?]

The Authors report two cases of primary carcinoma of the colon-rectum largely invasive, characterized signet ring cells. This is an uncommon neoplasm representing only 2% of primary carcinoma of the colon-rectum. The Authors discuss the diagnostic and therapeutic approach through a wide review of the literature.

[Diagnostic and therapeutic approach to kidney injuries]

The Authors report a wide review of the literature on open and blunt renal traumas. All the problems related to this pathology as well as all the instrumental and laboratory tests currently available for the correct diagnosis are illustrated. Both conservative and surgical management are also discussed.

Lipoperoxide plasma levels in patients with liver cirrhosis

BACKGROUND/AIMS

Oxygen free radicals might play a role in the pathogenesis of tissue damage in many pathological conditions, including liver diseases where antioxidant tissue systems are reduced. The leading mechanism of free radical toxicity is the peroxidation of membrane phospholipids. Lipoperoxide hydrolysis produces aldehydes -the most represented being malondialdehyde-which reacts with thiobarbituric acid and whose concentration is considered a marker of lipid peroxidation.

MATERIALS AND METHODS

We developed a fast and cheap HPLC method for measuring malondialdehyde concentration in plasma using a 3 mm C18 Baker column (4.6 x 50 mm). Thiobarbituric acid-reacting substances were eluted isocratically with a mobile phase containing methanol/KH2PO4 (35/65), and detected fluorometrically. The whole analysis lasts 2.5 minutes. The fasting levels of thiobarbituric acid-reactive substances were measured in 30 non-smoking blood donors and in 45 patients with liver cirrhosis.

RESULTS

In control subjects they were on average 0.84 [SD 0.41] mumol/L and were increased to 1.59 [SD 1.23] mumol/L in patients with cirrhosis, where they inversely correlated with hepatocellular function.

CONCLUSIONS

The method compares favorably with previous techniques in terms of cost and analytical time. It can be used for serial measurement of plasma lipoperoxide concentrations in response to oxidative stress or following drug administration. Our preliminary data confirms the presence of an oxidative stress in cirrhotic patients. Normal lipoperoxide levels in subjects with very advanced disease may be due to polyunsaturated fatty acid deficiency and/or enzyme defects.

Isozyme-dependent sensitivity of adenylyl cyclases to P-site-mediated inhibition by adenine nucleosides and nucleoside 3'-polyphosphates

Recombinant adenylyl cyclase isozyme Types I, II, VI, VII, and three splice variants of Type VIII were compared for their sensitivity to P-site-mediated inhibition by several adenine nucleoside derivatives and by the family of recently synthesized adenine nucleoside 3'-polyphosphates (Désaubry, L., Shoshani, I., and Johnson, R. A. (1996) J. Biol. Chem. 271, 14028-14034). Inhibitory potencies were dependent on isozyme type, the mode of activation of the respective isozymes, and on P-site ligand. For the nucleoside derivatives potency typically followed the order 2',5'-dideoxyadenosine (2',5'-ddAdo) > beta-adenosine > 9-(cyclopentyl)-adenine (9-CP-Ade) >/= 9-(tetrahydrofuryl)-adenine (9-THF-Ade; SQ 22,536), with the exception of Type II adenylyl cyclase, which was essentially insensitive to inhibition by 9-CP-Ade. For the adenine nucleoside 3'-polyphosphates inhibitory potency followed the order Ado < 2'-dAdo < 2',5'-ddAdo and 3'-mono- < 3'-di- < 3'-triphosphate. Differences in potency of these ligands were noted between isozymes. The most potent ligand was 2',5'-dd-3'-ATP with IC50 values of 40-300 nM. The data demonstrate isozyme selectivity for some ligands, suggesting the possibility of isozyme-selective inhibitors to take advantage of differences in P-site domains among adenylyl cyclase isozymes. Differential expression of adenylyl cyclase isozymes may dictate the physiological sensitivity and hence importance of this regulatory mechanism in different cells or tissues.

Nonacidotic proximal tubulopathy transmitted as autosomal dominant trait

The family of a patient with a nonacidotic and hypercalciuric proximal tubulopathy was studied. The proband showed glycosuria, aminoaciduria, tubular proteinuria, renal hypophosphatemia, and urate tubular hyporeabsorption without bicarbonate loss. He also presented increased urine calcium excretion, plasma 1,25-dihydroxyvitamin D, and enteral calcium absorption. Clinical consequences of the tubulopathy were osteopenia and calcium kidney stones. Fifteen of the proband's relatives were studied; six of them had renal hypophosphatemia, 10 presented hypercalciuria, and three showed both hypercalciuria and hypophosphatemia. No other reabsorption defects were observed. High plasma levels of 1,25-dihydroxyvitamin D were found in 13 family members; their values correlated positively with calcium excretion and negatively with tubular phosphate reabsorption. None produced stones or had reduced mineral bone density. Hypophosphatemia and hypercalciuria occurred in the two generations studied; their transmission was independent of gender, and male-to-male transmission occurred for both defects. Our findings suggest that a genetic alteration of proximal tubular function could cause multiple reabsorption defects in the proband or renal phosphate leakage in the proband's relatives. The genotypic alteration causing the proximal dysfunctions may be monogenic, with an autosomal dominant pattern of inheritance and variable expressivity. Increased calcium excretion may be due to the proximal tubular alteration; alternatively, it may be the result of a genetic background predisposing to idiopathic hypercalciuria. Phosphate and calcium loss could stimulate 1,25-dihydroxyvitamin D synthesis in proximal tubular cells.

IL-2-regulated expression of the monocyte chemotactic protein-1 receptor (CCR2) in human NK cells: characterization of a predominant 3.4-kilobase transcript containing CCR2B and CCR2A sequences

NK cells migrate in response to C-C chemokines, including monocyte chemotactic protein-1 (MCP-1) and MCP-3. Increased migration was observed in IL-2-activated NK cells. It was therefore of interest to define the expression in resting and activated NK cells of the MCP-1 receptor (CCR2) for which two cDNAs (A and B) have been described. Specific oligonucleotides and reverse-transcriptase PCR revealed the presence in activated NK cells and mononuclear phagocytes of the fragments expected on the basis of the reported cDNAs. In addition, amplification with a common A/B- and an A-specific oligonucleotide yielded an unexpected, abundant, 1649-bp fragment. Sequence analysis as well as Northern blotting and RNase protection with different probes revealed that the CCR2 gene is expressed in activated NK cells and mononuclear phagocytes as a predominant long transcript (3.4 kb) consisting of CCR2B, followed by a novel sequence (X), corresponding to an intron in the genome, and by a CCR2A-specific portion. The predominant long transcript is polyadenylated and present in the cytoplasm. The augmented migratory capacity of IL-2 activated vs resting NK cells was associated with increased CCR2 transcript levels.

IL-2-regulated expression of the monocyte chemotactic protein-1 receptor (CCR2) in human NK cells: characterization of a predominant 3.4-kilobase transcript containing CCR2B and CCR2A sequences

NK cells migrate in response to C-C chemokines, including monocyte chemotactic protein-1 (MCP-1) and MCP-3. Increased migration was observed in IL-2-activated NK cells. It was therefore of interest to define the expression in resting and activated NK cells of the MCP-1 receptor (CCR2) for which two cDNAs (A and B) have been described. Specific oligonucleotides and reverse-transcriptase PCR revealed the presence in activated NK cells and mononuclear phagocytes of the fragments expected on the basis of the reported cDNAs. In addition, amplification with a common A/B- and an A-specific oligonucleotide yielded an unexpected, abundant, 1649-bp fragment. Sequence analysis as well as Northern blotting and RNase protection with different probes revealed that the CCR2 gene is expressed in activated NK cells and mononuclear phagocytes as a predominant long transcript (3.4 kb) consisting of CCR2B, followed by a novel sequence (X), corresponding to an intron in the genome, and by a CCR2A-specific portion. The predominant long transcript is polyadenylated and present in the cytoplasm. The augmented migratory capacity of IL-2 activated vs resting NK cells was associated with increased CCR2 transcript levels.

[Mechanical endarterectomy: review of the literature and description of an original device]

The Authors, after a Literature review on endovascular invasive procedures used for inferior limbs obstructive arteriopathy, describe the use of a new device for mechanical endarterectomy. Through the latest acquired experience the importance of dissecting progressively the single layers of the atheroma plaque without arriving to a complete denudation of the arterial wall, so avoiding the risk of myointimal hyperplasia reactions, is outlined. The possibility of using endoarterial stents in case of more indaginous recanalization is also stressed.

Glutathione kinetics in normal man and in patients with liver cirrhosis

BACKGROUND/AIMS

The dynamics of glutathione in plasma has always been studied by bolus injections. Data are available suggesting that the low plasma levels of cirrhosis are due to decreased production in glutathione-producing tissues, mainly the liver. We aimed to measure the kinetics of glutathione during controlled steady-state conditions, and to determine the reasons for its reduced plasma levels in advanced cirrhosis.

METHODS

The plasma clearance of glutathione was measured in six control subjects and in ten patients with cirrhosis during a 2-step infusion study, producing steady-state levels approximately 5 and 10 times basal values. The plasma disappearance curve after infusion stop was used to determine the apparent volume of distribution and half-life of glutathione, and the estimated basal appearance rate.

RESULTS

The clearance of glutathione did not reject 1st-order kinetics, i.e., it was concentration-independent, and was nearly doubled in cirrhosis. The half-life of exogenous glutathione was not different, whereas the volume of distribution was larger in cirrhosis, in the same range as extracellular water. The endogenous basal appearance rate of glutathione was reduced by 50%, and correlated with liver function, measured by routine and dynamic tests.

CONCLUSIONS

The data confirm that the primary defect responsible for reduced glutathione in liver disease is a reduced production, possibly related to hepatocyte dysfunction and a block along the pathway of methionine metabolism.

Antibodies of the anti-Yo and anti-Ri type in the absence of paraneoplastic neurological syndromes: a long-term survey of ovarian cancer patients

In recent years several authors have described a close correlation between circulating antineuronal antibodies of different types and the occurrence of paraneoplastic neurological syndromes. Because this has not been widely accepted, we screened 300 serum samples from 181 ovarian cancer patients for the presence of circulating antineuronal antibodies by immunofluorescence. The findings were confirmed by immunoblotting. In 11 patients circulating antineuronal antibodies were detected. In 4 patients they were classified as anti-Yo and in 7 as anti-Ri, titres ranging from 1:400 to 1: 204,800. All the patients underwent thorough neurological and neurophysiological investigations, with special regard to paraneoplastic syndrome. None of them had symptoms pointing to a paraneoplastic neurological syndrome, although patients were followed up to 2 years after the first examination. Thus the frequency of circulating antineuronal antibodies in ovarian cancer patients is higher than the frequency of paraneoplastic syndromes, and antibody positivity does not necessarily lead to the appearance of a neurological paraneoplastic syndrome.

Effect of lactulose on carbohydrate metabolism and diabetes mellitus

BACKGROUND

Unabsorbable disaccharides, by reducing transit time and possibly glucose absorption, are expected to affect carbohydrate metabolism.

AIM

To test the effects of a preparation containing fibre and lactulose in the form of biscuits on glucose and insulin levels in obesity.

METHODS

In 10 obese patients glucose and insulin were measured in the fasting state and in response to a meal during two consecutive days on a strictly controlled diet; on one day a total of 11 biscuits (10 g dietary fibre, 2 g raw fibre +8.2 g lactulose) were randomly substituted for an equicaloric part of a diet.

RESULTS

Glucose and insulin in response to breakfast and to lunch were blunted by dietary fibre and lactulose, without any trend towards post-meal hypoglycaemia. Average day-time glucose decreased by 0.53 +/- SD 0.28 mmol/L, and insulin by 74.6 +/- 45.2 pmol/L. Plasma amino acids were higher during supplementation, ruling out malabsorption as a cause of glucose flattening.

CONCLUSION

Because of the rationale of the preparation, good compliance of patients, and significant results in short-term experiments, the association of fibre and lactulose deserves more careful evaluation in long-term clinical studies.