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Y Berland

Publications and source records attributed to Y Berland.

At least 55 records · Page 3Linked to original sources
PubMed1998

Urinary kidney stone inhibitors. What is the news?

Supersaturation with respect to calcium salts (oxalate and phosphate) is the driving force leading to crystalluria and nephrolithiasis. High-molecular-weight urinary inhibitors are recently described molecules capable of altering the process of kidney stone formation. By inhibition of crystal nucleation, growth and aggregation and by inhibition of crystal interaction with tubular cells, these proteins efficiently prevent stone formation and retention in the urinary tract. But in spite of considerable efforts, characterization of these proteins is still under way. Besides the pathophysiology of risk factors for calcium salts supersaturation such as idiopathic hypercalciuria or hyperoxaluria, the renal involvement of protein inhibitors is the most exciting field in the comprehensive approach of nephrolithiasis, a disease that affects up to 10% of people in Western countries.

Animals↗
PubMed1998

[Dialysate and biocompatibility in hemodialysis].

This article summarise the main data in the literature on the role of bacteriological contamination of the dialysate fluid in inflammatory reactions in hemodialysis. Pyrogenic substances of small molecular weight from Gram-negative bacteria grown in dialysate can pass across intact dialyzer membrane to stimulate cytokine production by peripheral blood mononuclear cells. Cellulosic hemodialysis membranes are more permeable to endotoxins than synthetic membranes. Polysulfone membranes and polyamide membranes are able to adsorb bacterial toxins on the dialysate side. The diffusive transfer of bacterial products across dialysis membrane from dialysate fluid was demonstrated. Transmembrane passage of cytokine-inducing bacterial products across reprocessed dialyzers is greater than across new dialyzers. Bacteriological contamination of the dialysate fluid is a problem which must be considered with much more care by nephrologists, especially as LAL test is unable to detect all the bacterial products which can contaminate the dialysate fluid.

Bacteria↗
PubMed1997

Prevalence of hepatitis G virus infection in kidney transplant recipients.

BACKGROUND: We investigated the prevalence, risk factors, and consequences of hepatitis G virus (HGV) infection in 87 kidney transplant recipients. METHODS: Infection was diagnosed with reverse transcriptase polymerase chain reaction using primers in the NS3 region of the viral genoma. RESULTS: Twenty-four patients (27.5%) were HGV RNA positive (HGV+ group) and 63 patients (72.5%) were HGV RNA negative (HGV- group). No statistically significant differences were found between the two groups for age, sex, transplantation and hemodialysis duration, number of kidney transplantations, serum creatinine, history of transfusions, hepatitis B and C virus infections, and percentage of patients having suffered from acute rejection. Acute and chronic hepatitis were not more prevalent in the HGV+ group than in the HGV- group. CONCLUSIONS: HGV infection is highly prevalent in kidney transplant recipients but does not alter liver or kidney functions. HGV contamination may be linked to nosocomial transmission during long-term hemodialysis.

Adult↗
PubMed1997

Sodium pump and Na+/H+ activities in uremic erythrocytes. A microcalorimetric and pH-metric study.

The sodium pump and Na+/H+ antiport activities in red blood cells from uremic hemodialyzed patients were measured concomitantly. The patients selected (n = 35) were normotensive and free of intercurrent illness known to affect Na transport. The Na pump activity of intact red blood cells in suspension in their own plasma was measured by flow microcalorimetry. The Na+/H+ antiport activity of the erythrocytes from the same patients was determined by a titrimetric technique. The mean global value of the sodium pump was lower in uremics than in controls (13.3 +/- 0.6 vs. 11.3 +/- 0.8 mW/l cells, P < 0.05). The Na+/H+ antiport maximal activity was decreased in uremics (2.9 +/- 0.3 vs. 4.6 +/- 0.5 mmol H+/l cells/h, P < 0.05). Our results thus confirm that uremia per se can affect sodium transport. Moreover it has been shown that a decrease in Na+/H+ antiport activity is able to counteract an impairment of sodium pump. The decrease found in this study could thus explain, at least in part, the absence of hypertension in the patients studied despite their decreased sodium pump activity.

Adult↗
PubMed1997

Trimetazidine does not modify blood levels and immunosuppressant effects of cyclosporine A in renal allograft recipients.

AIMS: In renal allograft recipients, trimetazidine (Vastarel) was proposed to be associated with the classic immunosuppressant treatments because it displays anti-ischaemic effects which may protect against cyclosporine A nephrotoxicity. The objective of this work was to assess the possibility of coadministering cyclosporin A, Sandimmun, and trimetazidine. METHODS: Twelve renal transplant patients were selected on the basis of the stability of their cyclosporine A blood concentrations for the previous 3 months. They received trimetazidine, 40 mg twice daily orally for 5 days. Other coadministered drugs were kept unchanged during the study. Before and after trimetazidine administration, cyclosporine A blood concentrations, plasma interleukin-2 and soluble interleukin-2 receptor levels were measured. RESULTS: The data showed that neither cyclosporin A blood pharmacokinetic parameters, Cmax, tmax, AUC, nor the concentrations of interleukin-2 and soluble interleukin-2 receptors were significantly modified. CONCLUSIONS: Therefore, it was suggested that trimetazidine may be coadministered with cyclosporine A without cyclosporine A dosage adjustment.

Adult↗
PubMed1997

[Tubular necrosis after non-steroidal anti-inflammatory agents and acute alcoholic intoxication].

Acute nephrotoxicity due to nonsteroidal anti-inflammatory drugs is usually observed in clinical situations in which renal perfusion is compromised as in volume contraction. We report a case of a 20 year-old woman who suffered from acute tubular necrosis after concomitant ingestion of nonsteroidal anti-inflammatory drugs and binge drinking. This acute tubular necrosis is likely to have an hemodynamic origin due to nonsteroidal anti-inflammatory drugs in a patient with volume contraction secondary to binge drinking. The risk appears to be even more important since ethanol has been implicated in tubular necrosis by direct toxicity. This observation underlines the danger in associating nonsteroidal anti-inflammatory drugs and ethanol.

Acute Kidney Injury↗
PubMed1997

Potential interest of anti-ischemic agents for limiting cyclosporin A nephrotoxicity.

Chronic administration of cyclosporin A induces nephrotoxicity in humans. This is related to a cyclosporin A-induced constriction of afferent glomerular arterioles and mesangial cells, which leads to a decrease in filtration pressure and creatinine clearance. Afterwards, cellular lesions are observed involving mainly tubular atrophy and interstitial fibrosis, both of which are nonspecific. The initial mechanism of its toxicity is not clearly explained. The current pharmacological approach is symptomatic in order to counteract or minimize the consequences of a prime cause, which still remains to be defined. However, cyclosporin A has a deletereous effect on mitochondrial functions and mainly on ATP synthesis, which occurs when Ca2+ accumulates in matrix mitochondria. The effects of trimetazidine, an antischemic drug used in the treatment of angina pectoris, have been assessed. This drug is effective in experimental models of hypoxia induced by cyclosporin A: it restores ATP synthesis previously decreased by Ca2+ and cyclosporin A, and releases a part of Ca2+ excess accumulated by mitochondria at concentrations reached in humans at usual dosage regimens. At higher concentrations, it reverses the mitochondrial permeability transition previously generated (opened) by Ca2+ and a pro-oxidant such as terbutylperoxide (t-BH). It was also observed that trimetazidine does not modify the immunosuppressive effects of cyclosporin A in various models. These data suggest that nephrotoxicity of cyclosporin A is not irrevocably linked to its immunosuppressive effect but that it may be possible to counteract at least partly its nephrotoxic effects without altering its effectiveness in preventing graft rejection.

Adenosine Triphosphate↗
PubMed1997

[Travel and renal insufficiency].

Traveling can be dangerous for subjects with kidney insufficiency. Water loss or septic episodes can further increase renal dysfunction. Poor diet can lead to hyperkaliemia. Immunosuppression not only enhances the risk of infection but also complicates administration of live vaccines. Some antimalarial drugs are contraindicated (e.g. mefloquine) and others must be used with precaution. Prior to departure persons requiring hemodialysis should book sessions at centers listed in specialized guidebooks. In addition to infection, risks for hemodialysis patients include thrombosis of the arteriovenous fistula in case of dehydration or hypotension. In subjects with transplanted kidney, the risk of rejection can be enhanced either by poor compliance with immunodepressor treatment or by vaccination-induced antigenic stimulation. Pre-travel evaluation is necessary to determine metabolic, nutritional, and immune status. Subjects with kidney insufficiency and transplanted kidneys should be informed of the dangers and appropriate action in case of trouble.

Anti-Infective Agents↗
PubMed1996

Pancreatic lithostathine as a calcite habit modifier.

Most biological fluids are supersaturated with calcium salts. A mechanism controlling crystal growth is therefore necessary to prevent excessive precipitation and development of a lithiasis. In pancreatic juice, calcite precipitation is prevented by lithostathine, a glycoprotein that inhibits calcite crystal growth. We describe here the interaction of lithostathine with calcite crystals. Without lithostathine, calcite crystals grew as rhombohedra showing six (104) faces. At low concentration (1 microM), lithostathine already altered crystal growth by generating new (110) faces. At physiological concentrations (3-10 microM), adsorption resulted in a transition from rhombohedral to sub-cubic habits. Immunochemical localization demonstrated that, although all (104) faces are equivalent, lithostathine binding was restricted to the face edges distal to the c axis. Scanning electron microscopy showed that, at the site of lithostathine binding, spreading of new CaCO3 layers during crystal growth was arrested before reaching the crystal diad axis-bearing edges. The successive kinks generated during crystal growth formed the new, striated (110)faces. Similar modifications were observed with the N-terminal undecapeptide of lithostathine that bears the inhibitory activity. With 100 microM lithostathine, (110) faces could reach the c axis outcrop of the former rhombohedron, resulting in an olive-shaped crystal. Finally, the number of crystals increased and their average size decreased when lithostathine concentration increased from 0.1 to 100 microM. Decreased Ca2+ concentration during crystal growth was delayed in the presence of lithostathine. It was concluded that lithostathine controls lithogenesis 1) by triggering germination of numerous calcite crystals and 2) by inhibiting the rate of Ca2+ ion apposition on the nuclei and therefore interfering with the apposition of new layers on calcite. Formation of smaller crystals, whose elimination is easier, is thereby favored.

Calcium Carbonate↗
PubMed1996

Calcium carbonate crystals promote calcium oxalate crystallization by heterogeneous or epitaxial nucleation: possible involvement in the control of urinary lithogenesis.

A large proportion of urinary stones have calcium oxalate (CaOx) as the major mineral phase. In these stones, CaOx is generally associated with minor amounts of other calcium salts. Several reports showing the presence of calcium carbonate (CaCO3) and calcium phosphate in renal stones suggested that crystals of those salts might be present in the early steps of stone formation. Such crystals might therefore promote CaOx crystallization from supersaturated urine by providing an appropriate substrate for heterogeneous nucleation. That possibility was investigated by seeding a metastable solution of 45Ca oxalate with vaterite or calcite crystallites. Accretion of CaOx was monitored by 45Ca incorporation. We showed that (1) seeds of vaterite (the hexagonal polymorph of CaCO3) and calcite (the rhomboedric form) could initiate calcium oxalate crystal growth; (2) in the presence of lithostathine, an inhibitor of CaCO3 crystal growth, such accretion was not observed. In addition, scanning electron microscopy demonstrated that growth occurred by epitaxy onto calcite seeds whereas no special orientation was observed onto vaterite. It was concluded that calcium carbonate crystals promote crystallization of calcium oxalate and that inhibitors controlling calcium carbonate crystal formation in Henle's loop might play an important role in the prevention of calcium oxalate stone formation.

Calcium Carbonate↗
PubMed1996

Tolerance of haemodialysis: a randomized cross-over trial of 5-h versus 4-h treatment time.

BACKGROUND: Many factors can impair haemodialysis (HD) tolerance. Some such as age and diabetes mellitus are linked to the patient. Others, such as dialysate, machine, and membrane are linked to the treatment characteristics. The duration of the HD sessions may represent another factor in tolerance since it influences the rate of ultrafiltration. However, its influence has not been studied independently of the type of membrane or dialysate buffer. METHODS: In a randomized crossover study, the incidence of intradialytic symptoms was compared during 4-h and 5-h HD sessions in 38 patients. The study period was 2 weeks for each dialysis time. The influence of age and diabetes was also analysed. Sessions requiring more than 4 litres of ultrafiltration were excluded. RESULTS: During the 5-h period, the incidence of headache, nausea, chills, back pain and pruritus was significantly greater. On the contrary, the incidence of hypotension and postdialytic orthostatic hypotension was significantly less. We also demonstrated that ultrafiltration rate and orthostatic hypotension were correlated, and that age over 65 years and diabetes influenced HD tolerance. The incidence of hypotension was significantly less in patients over 65 receiving 5-h HD treatment. CONCLUSIONS: Although some symptoms were more frequent during the 5-h HD sessions, the incidence of hypotension and postdialytic orthostatic hypotension was significantly less. This resulted in an improvement in acute haemodynamic HD tolerance, which could also influence long-term morbidity and mortality, especially in patients over 65 years.

Adult↗
PubMed1996

Bartonella (Rochalimaea) quintana infection in a seronegative hemodialyzed patient.

Bartonella quintana is a reemerging pathogen responsible for trench fever, endocarditis, bacteremia, and bacillary angiomatosis. We previously reported the first case of a patient with B. quintana-induced chronic adenomegaly, and here we present a report on a second patient. A hemodialyzed patient with Sjögren's syndrome presented with mediastinal adenomegalies and secondary pancytopenia. All diagnostic investigations remained negative, except that a Bartonella-like microorganism was isolated from a bone marrow biopsy. The isolate was identified as B. quintana by a specific mouse polyclonal antibody and by determination of a partial gltA (citrate synthase-encoding) gene and 16S rRNA gene sequences. DNA of the pathogen was also detected in the adenomegaly and in the serum of the patient by PCR amplification of the gltA gene. Anti-B. quintana antibodies were never detected in the patient's serum throughout the 12-month follow-up but were detected in the serum of the patient's cat. The patient's outcome was favorable after treatment with gentamicin. Chronic adenomegaly in seronegative patients is a new clinical entity due to B. quintana.

Adult↗
PubMed1996

Proliferative glomerulonephritis revealing chronic Q fever.

We describe the case of a 69-year-old male with a year-long history of renal failure. Investigation revealed proliferative glomerulonephritis, cryoglobulinemia, and Q fever endocarditis. Renal tissue examination for the presence of Coxiella burnetii was positive. The patient was treated by doxycycline and chloroquine; his clinical status, renal failure, and chronic Q fever have dramatically improved.

Aged↗