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Biomedical subjects

B Dussol

Publications and source records attributed to B Dussol.

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

Interactions between cyclosporine A and adenosine in kidney transplant recipients.

Adenosine is involved in a large number of physiological processes including immune response and vasomotor function. But its precise involvement in renal physiology is poorly understood. We have investigated the putative relationships between cyclosporine A (CsA) and adenosine (ADO) metabolism in kidney transplant recipients (KTR). We first compared ADO plasma levels in three groups of patients and in 10 controls: the first group (N = 14) was composed of CsA-treated KTR; the second group (N = 5) was KTR not treated with CsA, and the third (N = 6) was chronic kidney failure patients. We also measured ADO plasma level in two KTR treated with FK506, a CsA analog. ADO plasma levels in CsA-treated KTR were significantly higher (mean 0.76 microM +/- 0.27) than in the control group (mean 0.31 +/- 0.13; Mean-Whitney test, S = 8.5; P = 2.1 x 10(-4)) and than in the chronic kidney failure group (0.37 +/- 0.16, Mann-Whitney, S = 5.5; P = 1.6 x 10(-3)). In CsA-treated KTR, CsA and ADO plasma levels were significantly correlated (Spearman's, r = 0.8, P = 1.9 x 10(-3)). No significant differences in ADO plasma levels were found between patients with chronic kidney failure and controls (P < 0.05). ADO plasma levels in KTR not treated with CsA were in the same range as those in controls. Finally, the ADO plasma level was increased in the two FK506-treated patients. We also investigated the action of CsA on ADO plasma degradation and uptake by erythrocytes in vitro. No interaction between adenosine deaminase and CsA was found because CsA, in the presence of adenosine deaminase, did not modify the plasma half-life of ADO. Conversely, in the presence of CsA (500 and 1000 ng/ml), the uptake of ADO by erythrocytes was significantly decreased in adenosine deaminase-free samples (analysis of variance, P = 1.8.10(-3) and 1.2 x 10(-4), respectively). We conclude that ADO plasma levels are significantly elevated and correlate with CsA blood level in CsA-treated KTR, and that these high levels are due to CsA inhibition of ADO uptake by red cells. Since ADO and metabolites have well known immunosuppressive and vascular effects, ADO is likely to participate in the immune defect and in the vasoconstriction induced by CsA.

Adenosine↗
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

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↗
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

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

[Malignant histiocytofibroma of the bladder. A case report].

Malignant histiocytofibroma of the bladder is a rare (16 cases reported in the literature) and very aggressive sarcoma. It is sometimes associated with a haematological malignancy. The authors report a case of malignant histiocytofibroma of the bladder in a 72-year-old haemodialysed woman with a poor general status. She had a history of chemotherapy and radiotherapy for gastrointestinal lymphoma 6 years previously. Treatment consisted of palliative cystectomy for bladder pain and haematuria. A massive pelvic and abdominal wall recurrence occurred two months after cystectomy and the patient died. The authors review the 16 cases of malignant histiocytofibroma of the bladder reported in the literature. Histiocytofibroma is a tumour which requires aggressive treatment with a combination of radical surgery and systemic chemotherapy.

Aged↗
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↗
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

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↗