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Biomedical subjects

G Jean

Publications and source records attributed to G Jean.

At least 19 recordsLinked to original sources
PubMed1998

A novel gene encoding an integral membrane protein is mutated in nephropathic cystinosis.

Nephropathic cystinosis, an autosomal recessive disorder resulting from defective lysosomal transport of cystine, is the most common inherited cause of renal Fanconi syndrome. The cystinosis gene has been mapped to chromosome 17p13. We found that the locus D17S829 was homozygously deleted in 23 out of 70 patients, and identified a novel gene, CTNS, which mapped to the deletion interval. CTNS encodes an integral membrane protein, cystinosin, with features of a lysosomal membrane protein. Eleven different mutations, all predicted to cause loss of function of the protein, were found to segregate with the disorder.

Amino Acid Sequence↗
PubMed1997

Central venous catheters for haemodialysis: looking for optimal blood flow.

Central venous catheters are commonly used for haemodialysis patients and represent, in our centre, about 15% of the permanent vascular accesses with a total number of more than 230 central venous catheters over the last 10 years. Inadequate blood flow may occur and upsets the nurses, the patients, and the nephrologist. The aim of this study was to identify the factors of the catheter dysfunction. We studied prospectively 25 chronic haemodialysed patients with central venous catheters, 14 women and 11 men, 65 +/- 16 (55-89) years of age, treated with haemodialysis for 6.7 +/- 7 (1-26) years. Catheters were tunnelled silicone twin catheters (Permcath Quinton n = 18, Twincath Hemotec n = 7) in right (n = 19) and left internal jugular (n = 6) inserted by percutaneous Seldinger techniques. We studied the localization of the catheter tip (superior vena cava, right atrium, right ventricular, inferior vena cava), the central venous pressure before and after haemodialysis, the blood pressure (BP) before and after haemodialysis, the interdialytic weight gain, the number of symptomatic hypotensions during the 10 last dialyses. The patients were divided into two groups: group I with usual adequate catheter function (n = 18) and group II with frequent dysfunctions (n = 7). Central venous pressure before dialysis was significantly higher in group I with adequate blood flow and the catheter's tip was more frequently found localized in the right cardiac cavities than in the vena cava. When central venous pressure before dialysis was over 5 mmHg, no dysfunction occurred. Blood pressure was not different between the two groups. We found no correlation between central venous pressure and BP, interdialytic weight gain and symptomatic hypotensions. We could not predict the central venous pressure from the mean BP but there was a higher frequency of hypotensions in the hypovolaemic patients. Optimal haemodynamic conditions will be provided by a catheter tip in the right cardiac cavities and a central venous pressure over 5 mmHg which can be provided with vascular filling or dry weight revaluation.

Aged↗
PubMed1996

Congenital nephrotic syndrome of the Finnish type: linkage to the locus in a non-Finnish population.

Congenital nephrotic syndrome of the Finnish type (CNF) is inherited as an autosomal recessive trait. The biochemical basis of the disease is unknown, although a lesion in the glomerular basement membrane is strongly suggested. Recently, the CNF locus was assigned to chromosome 19q12-q13.1 on the basis of linkage analysis in Finnish families. The high incidence of the disease in Finland, as well as the demonstration of linkage disequilibrium in the Finnish study, strongly suggests a founder effect based on a common ancient mutation in this population. We confirm linkage of the CNF locus to the same chromosomal region in seven non-Finnish CNF families without evidence of linkage disequilibrium. Our results show that the same gene seems to be affected in both Finnish and non-Finnish CNF populations. However, in the latter the mutation-carrying chromosomes descend from different ancestors without evidence of a founder effect.

Africa, Northern↗
PubMed1996

Clinical assessment of dry weight.

Unsatisfactory control of blood pressure (BP) leading to an increased rate of cardiovascular events is the main cause of mortality in haemodialysis. BP control has deteriorated since haemodialysis session times have been reduced. Inadequate BP control most often is due to a failure to achieve and maintain dry weight. Dry weight and normotension have been gradually omitted in the goals of dialysis, satisfactory dialysis being reduced to an 'adequate' urea Kt/V. Ideal dry body weight needs a reappraisal. What is dry weight? How should it be clinically assessed, established and maintained in patients? The problems encountered in estimating dry weight can be solved at the bedside in most cases. The additional laboratory, echography and impedancemetry methods are research tools that hopefully can be made simpler and lower in cost so they can be used everyday at the bedside. In the mean time, with the exception of ambulatory blood pressure measurement, one must rely on careful and repeated clinical observation to determine and maintain dry weight.

Blood Pressure↗
PubMed1996

High-resolution mapping of the gene for cystinosis, using combined biochemical and linkage analysis.

Infantile nephropathic cystinosis is an autosomal recessive disorder characterized biochemically by an abnormally high intracellular content of free cystine in different organs and tissues due to a transport defect of cystine through the lysosomal membrane. Affected children present with the Fanconi syndrome and usually develop progressive renal failure within the 1st decade of life. Measurement of free cystine in purified polymorphonuclear leukocytes provides an accurate method for diagnosis and detection of heterozygous carriers. In order to localize the gene locus for cystinosis we performed linkage analysis in 18 cystinosis families. However, since 17 of these were simplex families, we decided to include the phenotypes of the heterozygous carriers previously determined by their leukocyte cystine content in the linkage analysis. This approach allowed us to obtain highly significant results, confirming the localization of the cystinosis gene locus recently mapped to the short arm of chromosome 17 by the Cystinosis Collaborative Research Group. Crucial recombination events allowed us to refine the interval of the cystinosis gene to a genetic distance of 1 cM. No evidence of genetic heterogeneity was found. Our results demonstrate that the use of the previously determined phenotypes of heterozygous carriers in linkage analysis provides a reliable method for the investigation of simplex families in autosomal recessive traits.

Chromosome Mapping↗
PubMed1995

Mapping a gene (SRN1) to chromosome 1q25-q31 in idiopathic nephrotic syndrome confirms a distinct entity of autosomal recessive nephrosis.

Idiopathic nephrotic syndrome (INS) in childhood is characterized by massive proteinuria and minimal glomerular changes. Most patients with INS respond to steroid therapy. INS is generally regarded as a sporadic disease with favorable outcome. We investigated a distinct subgroup of nephrosis--the familial form of steroid resistant INS (SRN). These patients always progress to end-stage renal failure within a few years and show absence of recurrence of the disease after renal transplantation. The occurrence of the disorder in siblings and the high incidence of inbreeding in these families made an autosomal recessive mode of inheritance very likely. We performed whole genome linkage analysis in nine multiplex families of European or Northern African origin. Our results allowed us to assign a disease locus (SRN1) to a defined chromosomal region on 1q25-1q31, thus confirming the existence of a distinct entity of autosomal recessive nephrosis. Exclusion of linkage to the entire region in one family proves genetic heterogeneity.

Chromosome Mapping↗
PubMed1995

Sleep apnea incidence in maintenance hemodialysis patients: influence of dialysate buffer.

A high prevalence of sleep disorders and sleep apnea syndrome in hemodialysis (HD) patients has been known for 10 years. Acetate, the buffer once most commonly used, favors intradialytic hypoxemia through hypoventilation and ventilation-perfusion changes. The aim of the present study was to assess the influence of buffer, acetate or bicarbonate, on sleep and ventilation during the night subsequent to an afternoon (2-7 p.m.) dialysis session. Ten patients, 8 males and 2 females, aged 35-71 years, dry weight 55-72 kg, on dialysis 15 h a week for 6-67 months, were randomly assigned first to acetate or bicarbonate, then to the other mode of treatment. After a series of six sessions using the same buffer, polysomnographic recordings from 9.00 p.m. to 6.00 a.m. were obtained. Sex, age, weight, data of first dialysis, blood pressure and sleep disorder-related symptoms were not correlated with the sleep apnea syndrome. Prolonged or important oxygen desaturations were never observed. Central apnea occurred more frequently during the night following acetate dialysis: x = 33 (0-180) versus 3 (0-15), p < 0.05. Obstructive apneas were not different. A defective modulation of ventilatory control after acetate HD might be held responsible for central apnea, which would constitute one more case for a widespread use of bicarbonate HD.

Acetates↗
PubMed1994

Altered leukotriene generation in leukocytes from cystinotic children.

Upon in vitro stimulation with 10 microM ionophore A 23187 for 5 min at 37 degrees C, the generation of leukotriene (LT) C4 in polymorphonuclear leukocytes (PMNL) from nine untreated cystinotic children was significantly increased compared with that in eight control children (p < 0.01) and 25 normal adults (p < 0.001) (417.4 +/- 70.0 versus 177.0 +/- 30.9 and 164.9 +/- 19.5 pmol/l x 10(7) cells, respectively). Concomitantly with the increased generation of LTC4, LTB4 production in PMNL from untreated cystinotic children was decreased compared with controls, whereas the total amount of LTA4 derivatives was similar in the three groups. The increase in LTC4 production was not related to the number of eosinophils present in the PMNL preparations from cystinotic children, which was similar to that of control subjects. PMNL from cystinotic children treated with cysteamine, an aminothiol compound that decreases the intracellular cystine content, generated smaller amounts of LTC4 upon ionophore A 23187 stimulation than PMNL from untreated cystinotic children. In addition, abrogation of the cysteamine treatment for 3 or 4 d led to an increase in LTC4 production. These findings suggest that the metabolic abnormalities taking place in infantile cystinosis may favor the biosynthesis of LTC4 from PMNL.

Adult↗
PubMed1994

[Echographic localization for percutaneous internal jugular vein catheterization].

The standard internal jugular vein access is an anatomical-landmark method and the individual variations causes technical difficulty and sometimes morbidity. Ultrasound guidance for percutaneous puncture of internal jugular vein is used in 20 patients for hemodialysis catheter insertion. This method allow the visualization of jugular permeability and needle progression during puncture. A control historical group comparison emphasized the advantage of this technique with lower access time (20 s vs 90 s), more first needle pass success (90% vs 50%) and reduced morbidity (carotid puncture, hematomas). The ultrasound guidance is very simple and safe but major disadvantage is the cost of the equipment.

Adult↗
PubMed1994

[Comparison of the functional survival in chronic renal insufficiency of Permcath jugular catheters according to their mode of insertion].

The functional survival of the same silicone double lumen catheter (DLC) was analyzed in relation with the mode of its insertion. Thirty-seven catheters were surgically inserted (34 in the right internal Jugular vein, 3 in the left internal Jugular vein), while 28 were percutaneously inserted (25 in the right internal Jugular vein, 3 in the left internal Jugular vein). The functional survival was calculated using Kaplan Meier method. Significant survival difference was looked for with log rank test. The maximum follow-up time was 62 months for surgically inserted DLC and 12 months for their percutaneous counterpart. There was no significant functional survival difference between the two groups at one year. At this term 86% of DLC were still in use. We conclude from our experience that the mode of insertion does not significantly modify the success rate of this type of blood access. The simplest and lightest method (i.e. percutaneous) should therefore be preferred.

Adult↗
PubMed1994

[Effect of catheter type on the functional survival of jugular access ports in chronic hemodialysis].

Silicone catheter (C) can be used in the hemodialysis setting as an alternative for the blood access. We analysed retrospectively the 3 types of the catheters used in 45 patients. 58 catheters were percutaneously inserted in the internal jugular vein (9 Bard (B)-Hickman; 17 Canaud (CD)-Vygon; 32 Permcath (PC)-Quinton). The indications were thrombosis or dysfunction of an arterio-venous fistula (A-V F) (52%), absence of a A-V F (21%), Thomas' shunt infection (8%), infection or extrusion of a previous catheter (19%). The functional survival curve of the C shows the best results for the PC and the worse with the B (Log-Rank test = 6,602, p < 0.037). The main cause of failure was the catheter's extrusion (3 of the 5 failures for the B; 4 of the 6 for the CD). None of the PC was extruded. Infection and inadequate blood flow were equally found in the 3 groups. In our experience, PC give the best results because of the quality of the cuff making a good attachment in the sub-cutaneous tunnel.

Aged↗
PubMed1994

[Temporary vascular access for extra-renal detoxification: utilization of tunneled silicone double-lumen catheters by the percutaneous route].

Femoral or subclavian central venous catheters are commonly used for temporary vascular access in haemodialysis. We used 36 tunnelized siliconed double lumen catheter (Quinton Permcath or Hickman Bard), most of them in right internal jugular percutaneously. Indication for this catheter were acute or chronic renal failure, plasma exchange, rescue of arterio venous fistula or peritoneal dialysis. Insertion incidents were minors (local haematoma), mean functional time was 51 days. Catheters were changed in 5 cases of infection, 3 cases of obstruction and in 2 accidental remove. Insertion facility, low morbidity, potentially long time use, high blood flow rate with low recirculation argue for this expensive material.

Adult↗
PubMed1993

[Volumetric analysis of urinary erythrocytes in the etiological diagnosis of hematuria].

Intravenous pyelography and cystography may fail to localize the origin of haematuria. Microhaematuria is known to be present in 2 to 10 percent of the general population, usually without pathological consequences. Study of red cell morphology by phase contrast microscopy is effective in distinguishing between "glomerular" (from renal tissue) and "non-glomerular" (from urinary tract) erythrocytes, but this technique is not currently available in all laboratories. Urinary blood cell volume analysis has been presented as a simple and automatic alternative method. We compared these two techniques in 100 cases of haematuria of various origins. The cut-off point between glomerular and non-glomerular erythrocytes was set at 71 fl. Phase contrast microscopy always confirmed the clinical and/or histological diagnosis, but volume analysis did not: mean erythrocyte volume of glomerular origin was 66.6 +/- 10.4 fl, while non-glomerular volume was 94.5 +/- 17 fl (P < 0.001); cell volume analysis was confirmative in only 72 percent of all diagnoses (65 percent of microhaematurias, 83 percent of macrohaematurias); sensitivity was 65 percent and specificity 85 percent for glomerular erythrocytes. Due to poor performance, urinary red volume analysis is not an acceptable alternative method to phase contrast microscopy when searching for the site of bleeding.

Adolescent↗
PubMed1993

Anti-OKT3 response following prophylactic treatment in paediatric kidney transplant recipients.

The anti-OKT3 response was studied in 40 paediatric kidney transplant recipients receiving OTK3 as a prophylactic treatment in association with azathioprine and prednisone. Only 1 patient experienced a reversible acute rejection episode while receiving OKT3. OKT3 induced a rapid disappearance of CD3+ cells, but significant proportions of CD3+ cells reappeared before the end of the treatment in 14 patients. Wide variations in circulating OKT3 levels were observed and in only 50% of patients could stable circulating OKT3 levels be detected until discontinuation of treatment. Anti-OKT3 antibodies detected by the enzyme-linked immunosorbent assay (ELISA) (anti-idiotypic and anti-isotypic antibodies) developed in 91% of patients. Anti-idiotypic antibodies detected by the immunofluorescence inhibition test were found in the sera of 71% of patients, always when high titres of anti-OKT3 antibodies were detected by ELISA. As it has recently been shown that anti-idiotypic antibodies are associated with failure of subsequent OKT3 treatment, we conclude that OKT3 should be restricted to steroid-resistant rejection crises in paediatric patients.

Adolescent↗