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Biomedical subjects

Y Berland

Publications and source records attributed to Y Berland.

At least 37 records · Page 2Linked to original sources
PubMed2000

Timing of nephrology referral: influence on mortality and morbidity.

To assess the influence of the timing of nephrology referral on the short- and long-term outcome of hemodialysis patients, we retrospectively studied 309 patients who had end-stage renal failure and entered the chronic hemodialysis program in Sainte-Marguerite University Hospital between January 1, 1989, and December 31, 1996. We excluded from the analysis five patients without available data on referral pattern and 34 patients with irreversible acute renal failure. Of the remaining 270 patients, 177 patients (58%) had an early referral (ER) 16 or more weeks before the start of dialysis, and 93 patients (31%) had a late referral (LR) of less than 16 weeks before dialysis. Short-time morbidity (initial emergent dialysis, pulmonary edema, severe hypertension, temporary vascular access placement for first dialysis, prolonged initial hospitalization) was significantly more frequent in LR patients. Long-term evolution (mean follow-up, 26.5 +/- 26 months) did not differ between the two groups. The number of days of hospitalization per patient-year at risk beyond the third month was 21.5 +/- 33.7 days for ER and 21.1 +/- 36 days for LR patients. Survival analysis showed no difference between the two groups: 3-month survival rates were 96% in both groups, 1-year survival rates were 90% in the ER and 89% in the LR group, and 5-year survival rates were 52% in the ER and 56% in the LR group. In a Cox hazards regression model, referral pattern was not associated with a greater risk for death. In conclusion, delayed nephrology referral generated strikingly greater initial morbidity, but long-term outcome of hemodialysis patients was not modified by delayed nephrological care.

Adolescent↗
PubMed2000

Comparative CD43 behavior on monocytes and lymphocytes in kidney transplants.

In human cultured monocytic cells stimulated by cytokines, CD43 was demonstrated to exhibit a modification of sialylated epitopes (dys-sialylation) [Soler et al: Leukoc Biol 1997;61:609-618]. Therefore, we chose to investigate CD43 behavior on patients who present pathological status implicating monocytes after renal graft (KTR). We performed flow cytometry after immune staining using monoclonal antibodies to CD43 sialic acid-dependent (L60) and -independent (L10) epitopes. Compared to normal controls, mean fluorescence intensity was never altered on lymphocytes. Conversely, on monocytes, we found different profiles with L60: 26% of patients having normal CD43 expression, 54% displayed decreased values and 20% had a double population of monocytes, the major one being normal and the minor one with a very low staining. Decreased values were more frequent among KTR during the first 3 months following transplantation. L10 immunostaining was not altered on monocytes in patients with low values of CD43 staining by L60, confirming that the mechanism involved was a CD43 dys-sialylation. We investigated a possible role of cyclosporin (CsA) on human monocytic (THP-1) and lymphoid (Jurkat) cell lines. CsA decreases CD43 expression in monocytic and not in lymphoid cell lines and could be responsible for the specific dys-sialylation of KTR monocytes. Whatever, CD43 dys-sialylation might lead to functional abnormalities of monocytes in KTR, possibly involving the adhesion process.

Adolescent↗
PubMed2000

The French Virtual Medical University.

This paper is the description of a French Virtual Medical University based on the federation of existing or currently being developed resources in several Medical Schools in France. The objectives of the project is not only to share experiences across the country but also to integrate several resources using the New Information and Communication Technologies to support new pedagogical approaches for medical students and also for continuing medical education. The project includes: A virtual Medical Campus using secure access from several sites, The Integration of new interactive resources based on pedagogical methods, Implementation of new indexing and search engines based on medical vocabularies and ontologies, The definition of general and specific portals, the evaluation of the system for ergonomics and contents.

Computer-Assisted Instruction↗
PubMed1999

Biophysical characterization of lithostathine. Evidences for a polymeric structure at physiological pH and a proteolysis mechanism leading to the formation of fibrils.

Lithostathine is a calcium carbonate crystal habit modifier. It is found precipitated under the form of fibrils in chronic calcifying pancreatitis or Alzheimer's disease. In order to gain better insight into the nature and the formation of fibrils, we have expressed and purified recombinant lithostathine. Analytical ultracentrifugation and quasi-elastic light scattering techniques were used to demonstrate that lithostathine remains essentially monomeric at acidic pH while it aggregates at physiological pH. Analysis of these aggregates by electron microscopy showed an apparently unorganized structure of numerous monomers which tend to precipitate forming regular unbranched fibrils. Aggregated forms seem to occur prior to the apparition of fibrils. In addition, we have demonstrated that these fibrils resulted from a proteolysis mechanism due to a specific cleavage of the Arg(11)-Ile(12) peptide bond. It is deduced that the NH(2)-terminal undecapeptide of lithostathine normally impedes fiber formation but not aggregation. A theoretical model explaining the formation of amyloid plaques in neurodegenerative diseases or stones in lithiasis starting from lithostathine is described. Therefore we propose that lithostathine, whose major function is unknown, defines a new class of molecules which is activated by proteolysis and is not involved in cytoskeleton nor intermediate filament functions.

Alzheimer Disease↗
PubMed1999

Cyclosporine A and purinergic receptors in rat kidney.

Previous reports have demonstrated that Cyclosporine A (CyA) chronically administered induces an increase in adenosine plasma concentration by inhibiting adenosine uptake by red blood cells (RBC). We hypothesized that this effect may modulate, by a down regulation, the mRNA expression of adenosine receptors in rat kidney. Since high blood pressure (HBP) is a classical side effect of CyA treatment, nicardipine, a dihydropyridine calcium channel blocker, is often associated with CyA in treatment. To distinguish between the effects of CyA-induced HBP and the effects of CyA by itself, we have evaluated the effects of CyA and/or nicardipine on the mRNA expression of A1 and A2a adenosine receptors. The study was performed on five groups of rats (n= 8) receiving during 21 days either serum saline (0.5 ml i.p), CyA (12 mg/kg/day, i.p), nicardipine (1.2 mg/kg i.p) or nicardipine + CyA. The last (or fifth) group was injected with vehicle (0.5 ml i.p). Blood samples for adenosine assay were collected in the renal artery at day 21, just before the rat kidneys were removed for quantitation of adenosine A1 and A2a mRNA concentration by RT-PCR. We make two conclusions :i) Nicardipine induces a decrease in mRNA expression of A1 but not of A2a adenosine receptors. However, because nicardipine lowered both blood pressure and A1 mRNA expression, it is not possible to conclude if A1 mRNA decrease is implicated in the nicardipine effects on blood pressure.ii) CyA induces an increase in renal artery adenosine concentration and a decrease in mRNA expression of A1 and A2a adenosine receptors.

Adenosine↗
PubMed1999

[Neoplastic disorders and organ transplantation].

INTRODUCTION: Organ transplantation is associated with an increased risk of neoplasia, which seems to be caused by the total effect of immunosuppression, i.e., the combination of factors involved, rather than by the use of a specific class of immunosuppressants. The presence and proliferation of viral oncogenes is frequently observed during this immunosuppressive state. The neoplasia in immunosuppressed patients therefore has particular histological, clinical, evolutive, and therapeutical characteristics. CURRENT KNOWLEDGE AND KEY POINTS: The oncogenic mechanisms in immunosuppressed patients have been progressively clarified. A viral infection is associated with each type of neoplasia: thus, B lymphoma are generally associated with Epstein-Barr viral infection. Skin and uterine cervical carcinomas frequently appear after viral dysplasia due to papillomavirus. The significant increase in the incidence of Kaposi sarcoma shows the role of the immune system in the control of the infection by the human herpes virus 8, which has been recently discovered. Liver cancer is associated with a history of hepatitis B or C chronic infection. FUTURE PROSPECTS AND PROJECTS: Post-transplantation neoplasia constitutes a major problem in patient follow-up, as the number of transplant patients has increased and their survival rate has improved. In addition, there is an increasingly powerful new generation of immunosuppressive drugs. A precise knowledge of the immune system's control mechanisms regarding neoplasic cells and viral infection is an important step in the prevention and efficient treatment of these forms of cancer. Further research into the relationship between the immune system and viral oncogenesis should therefore be considered a major aim.

Follow-Up Studies↗
PubMed1999

Nucleation of calcium oxalate crystals by albumin: involvement in the prevention of stone formation.

BACKGROUND: Urine is supersaturated in calcium oxalate, which means that it will contain calcium oxalate crystals that form spontaneously. Their size must be controlled to prevent retention in ducts and the eventual development of a lithiasis. This is achieved, in part, by specific inhibitors of crystal growth. We investigated whether promoters of crystal nucleation could also participate in that control, because for the same amount of salt that will precipitate from a supersaturated solution, increasing the number of crystals will decrease their average size and facilitate their elimination. METHODS: Albumin was purified from commercial sources and from the urine of healthy subjects or idiopathic calcium stone formers. Its aggregation properties were characterized by biophysical and biochemical techniques. Albumin was then either attached to several supports or left free in solution and incubated in a metastable solution of calcium oxalate. Kinetics of calcium oxalate crystallization were determined by turbidimetry. The nature and efficiency of nucleation were measured by examining the type and number of neoformed crystals. RESULTS: Albumin, one of the most abundant proteins in urine, was a powerful nucleator of calcium oxalate crystals in vitro, with the polymers being more active than monomers. In addition, nucleation by albumin apparently led exclusively to the formation of calcium oxalate dihydrate crystals, whereas calcium oxalate monohydrate crystals were formed in the absence of albumin. An analysis of calcium oxalate crystals in urine showed that the dihydrate form was present in healthy subjects and stone formers, whereas the monohydrate, which is thermodynamically more stable and constitutes the core of most calcium oxalate stones, was present in stone formers only. Finally, urinary albumin purified from healthy subjects contained significantly more polymers and was a stronger promoter of calcium oxalate nucleation than albumin from idiopathic calcium stone formers. CONCLUSIONS: Promotion by albumin of calcium oxalate crystallization with specific formation of the dihydrate form might be protective, because with rapid nucleation of small crystals, the saturation levels fall; thus, larger crystal formation and aggregation with subsequent stone formation may be prevented. We believe that albumin may be an important factor of urine stability.

Adult↗
PubMed1999

TT virus infection in French hemodialysis patients: study of prevalence and risk factors.

The TT virus (TTV) is a recently discovered DNA virus which was first identified in patients with non-A to -G hepatitis following blood transfusion. In this study, we tested 150 attendees of two hemodialysis (HD) units of the public hospitals of Marseilles, France, for the presence of TTV genome by using a PCR-based methodology. The overall prevalence of TTV viremia was 28% (compared to 5.3% in blood donors from the same region). We demonstrated the existence of chronic infections and superinfections by strains belonging to different genotypes. The prevalence of infection was higher in patients originating from Africa, in patients with previous blood transfusion or organ transplantation, in patients with antibody to hepatitis B core antigen, and in those with diabetes mellitus. A high prevalence of TTV infection (50%) was also observed in a population of patients with diabetes mellitus but without renal disease. No significant relationship was found between TTV viremia and hepatitis C virus or GB virus C, transaminases, age, sex, and duration of HD treatment. The PCR amplification products (located in open reading frame 1 of the TTV genome) were sequenced. These genomic sequences were submitted to phylogenetic analysis by using the Jukes-Cantor algorithm for distance determination and the neighbor-joining method for tree building. In several instances, sequences from viruses isolated in a HD unit were grouped in the same phylogenetic cluster. These results together with the different distribution of cases in the two HD units suggest there is viral transmission within each.

Adult↗
PubMed1999

[Idiopathic calcium oxalate urinary lithiasis: new physiopathological approaches].

Nephrolithiasis effects 1% to 5% of the general population in industrialized countries. The majority of stones is made of calcium oxalate. The formation of calcium oxalate nephrolithiasis depends on several factors: hypercalciuria, hyperoxaluria, adhesion of crystals on the surface of renal epithelial cells, quantitative or qualitative deficit of inhibitors of crystallization in urine, intervention of promotors of crystallization. In this review we report the new insights into calcium oxalate stone formation.

Calcium↗
PubMed1998

Posttransplantation acute tubular necrosis: risk factors and implications for graft survival.

Previous studies aimed at identifying the causes, risk factors, and outcome of kidney transplant recipients with delayed graft function (DGF) have yielded controversial results. We retrospectively analyzed the causes and risk factors for DGF in 263 cadaveric kidney transplantations from November 1988 to March 1997 in one center. Causes of DGF were assessed by postoperative graft evolution and graft biopsy. Univariate and multivariate analysis were used to investigate the risk factors for DGF induced by acute tubular necrosis (ATN). Seventy-six patients (29%) had DGF, which was caused by ATN in 70 patients (92.1%) and acute rejection (AR) in 6 patients (7.9%). Therefore, we focused on risk factors and consequences for ATN-induced DGF. In monofactorial analysis, ATN was significantly associated with greater weight and presence of an atheromatous disease in both donor and recipient. Other risk factors for ATN were older age of donor, recipient American Society of Anesthesiology (ASA) physical status category IV, cold ischemia time (CIT), and transplantation using the right kidney. The multivariate analysis showed that donor and recipient weight, donor age, transplantation using the right kidney, preservation in Eurocollins solution, ASA score, and CIT were associated with ATN. The incidence of rejection and renal function were not different at 3 months or 1 and 5 years. ATN is the main cause of DGF in kidney transplant recipients. ATN is caused by donor and recipient vascular background, grafting the right kidney, and CIT. ATN does not appear to have an adverse effect on long-term kidney function.

Adult↗
PubMed1998

Adenosine and the nervous system: pharmacological data and therapeutic perspectives.

1. Adenosine acts on a family of G-protein-coupled receptors called purinoreceptors. 2. Four subtypes have been cloned and pharmacologically characterized. 3. The principal pharmacological data and structure-function relations for agonist interactions with P1 receptors are presented. 4. We conclude that the potent role of adenosine in the nervous system may be interesting for the development of drugs targeted at purines and their receptors.

Adenosine↗
PubMed1998

Effect of uremia and hemodialysis on soluble L-selectin and leukocyte surface CD11b and L-selectin.

Leukocyte Mac-1 (CD11b/CD18) and L-selectin (CD62L) are implicated in leukocyte adhesion to endothelial cells. In this study, L-selectin and CD11b expression on leukocytes and soluble L-selectin (sL-selectin) serum levels were investigated in 17 nondialyzed patients with chronic renal failure (CRF), in 28 chronic hemodialysis patients before hemodialysis (basal state), and in 32 healthy subjects. These parameters were also monitored during hemodialysis with cuprophane and cellulose diacetate membranes in a crossover study in five patients. Granulocytes from CRF patients displayed lower expression of L-selectin and higher expression of CD11b than granulocytes from healthy subjects. On the other hand, baseline expression of L-selectin and CD11b on leukocytes from hemodialysis patients did not differ from that of healthy subjects. In CRF and hemodialysis patients, sL-selectin levels were significantly lower than in healthy subjects. During hemodialysis, cuprophane membrane induced an upregulation of granulocyte CD11b, a decrease in granulocyte L-selectin, and an increase in sL-selectin serum levels. Conversely, cellulose diacetate caused only a transient increase in granulocyte CD11b and did not modify granulocyte L-selectin and sL-selectin serum levels. High CD11b and low L-selectin expression on granulocytes in CRF patients suggests an activation state, which was not found in hemodialysis patients at the basal state. The lack of activation in hemodialysis patients could reflect the elimination of a uremic toxin by dialysis or a loss of granulocyte responsiveness because of the repetitive stimulation by hemodialysis treatment. The low serum levels of sL-selectin in CRF and hemodialysis patients also suggest granulocyte dysfunction.

Biocompatible Materials↗
PubMed1998

Dietary and urinary risk factors for stones in idiopathic calcium stone formers compared with healthy subjects.

BACKGROUND: The high social-economic cost of nephrolithiasis wholly justifies the attempts to understand its mechanism and avoid recurrences. The influence of dietary habits and urinary risk factors has been evaluated, but the results were discrepant, probably because of differences in the methodologies used to compare patients and controls. METHODS: The aim was to assess dietary and urinary risk factors for urinary stones by comparison between 108 calcium stone formers (SF) and 210 healthy subjects (HS). All subjects were recruited during the same 1 year period. Personal characteristics, dietary habits (evaluated through a food frequency questionnaire) and urinary biochemical parameters were collected. The high predominance of men in the SF group led us to focus on the 79 SF and the 96 HS men. RESULTS: A familial history of stones was reported more frequently in SF than in HS, 42.9% vs 17.6%, P<0.005. Body weight was higher in SF, 76.8+/-12.2 kg vs 72.8+/-9.6 kg, P=0.02; and calcium intake was lower in SF, 794.8+/-294.1 mg vs 943.6+/-345.4 mg, P<0.01. For urinary parameters, calcium and oxalate output were significantly higher in SF. Urinary urea, as a reflection of daily protein intake, and uric acid were also higher in SF. Urinary citrate excretion related to body weight was lower in SF. Calciuria was significantly correlated with urinary urea in both SF and HS, but the correlation was stronger for SF. Calciuria correlated significantly with natriuria only in HS. CONCLUSIONS: The main differences between SF and HS were that SF had a family history of stones, a higher body weight, a lower daily intake of calcium, and a higher urinary output of calcium and oxalate. These results underline the combined role of genetic and nutritional factors in the pathogenesis of urinary stone formation.

Calcium Oxalate↗
PubMed1998

IL-10 synthesis and secretion by peripheral blood mononuclear cells in haemodialysis patients.

PURPOSE OF STUDY: IL-10 may explain the paradox between immunodeficiency and oversecretion of cytokines in chronic haemodialysis (HD) patients. We analysed the secretion of IL-10 by PBMC and the expression of IL-10 mRNA in 10 long-term HD patients (108-276 months), 10 short-term HD patients (3-18 months), and 10 healthy controls. RESULTS: Spontaneous IL-10 secretion was higher in HD patients than in controls (15 pg/ml vs 2 pg/ml, P = 0.004). It was detected in 13 of 20 patients and in 1 of 10 controls (P = 0.01). IL-10 mRNA expression was also higher in HD patients than in controls. Spontaneous secretions of IL-10 and IL-6 were positively correlated in patients. IL-10 secretion in response to LPS was higher than the upper limit of control range in 4 of 10 long-term HD patients and in no short-term HD patients (P = 0.04). IL-10 mRNA expression was also higher in long-term than in short-term HD patients. CONCLUSIONS: This study demonstrates that IL-10 is spontaneously synthesized and secreted in HD patients, supporting an immunomodulating role in this setting. The greater IL-10-producing capacity in long-term HD patients indicates a chronic effect of haemodialysis on PBMC responsiveness.

Adult↗
PubMed1998

A sensor-based evaluation of heart contractility in patients with head-up tilt-induced syncope.

Studies using the head-up tilt test (HUT) suggest that a reflex increase in sympathetic activity resulting in vigorous myocardial contractions precedes neurally-mediated syncope (NMS). The aim of this study was to evaluate heart contractility changes during positive HUT. Ten patients with recurrent NMS and positive HUT were investigated. Before HUT we temporarily placed a standard right ventricular pacing electrode incorporating in its tip a recently developed microaccelerometer (Sorin Biomedica, Italy) that measures the peak endocardial acceleration (PEA) during the isovolumetric phase as an index of heart contractility. PEA potential amplitude, heart rate and mean blood pressure were continuously studied during HUT. Syncope occurred 16.7 +/- 10.3 min after 60 degrees tilt, either at baseline (8 patients) or after sublingual nitrate administration (2 patients). PEA value was stable at 0.62 +/- 0.34 (1G = 9.8 m/sec2) during the supine phase. It slightly increased to 0.72 +/- 0.44 G (p = NS) during the first minutes of 60 degrees tilt and then remained unchanged until a further increase of 71 +/- 79% (range 10 to 266%) as compared to tilt value (p = 0.004) at 2.8 +/- 2.4 min (range 0.25 to 6.5 min) before the syncope in 9 patients. The latter increase was not observed in the patient with dilated cardiomyopathy. In conclusion, a significant increase in heart contractility was observed in 9 patients in the minutes preceding HUT-induced NMS. These changes might be used for driving a rate adaptive pacemaker when cardiac pacing is indicated to prevent NMS.

Electrodes, Implanted↗