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G Deschenes

Publications and source records attributed to G Deschenes.

9 recordsLinked to original sources
PubMed1998

Human complement factor H deficiency associated with hemolytic uremic syndrome.

This study reports on six cases of deficiency in the human complement regulatory protein Factor H (FH) in the context of an acute renal disease. Five of the cases were observed in children presenting with idiopathic hemolytic uremic syndrome (HUS). Two of the children exhibited a homozygous deficiency characterized by the absence of the 150-kD form of Factor H and the presence, upon immunoblotting, of the 42-kD Factor H-like protein 1 (FHL-1) and other FH-related protein (FHR) bands. Southern blot and PCR analysis of DNA of one patient with homozygous deficiency ruled out the presence of a large deletion of the FH gene as the underlying defect for the deficiency. The other four children presented with heterozygous deficiency and exhibited a normal immunoblotting pattern of proteins of the FH family. Factor H deficiency is the only complement deficiency associated with HUS. These observations suggest a role for FH and/or FH receptors in the pathogenesis of idiopathic HUS.

Acute Disease↗
PubMed1997

Mutations in the ROMK gene in antenatal Bartter syndrome are associated with impaired K+ channel function.

Children with the antenatal variant of Bartter syndrome present the typical pattern of impaired salt reabsorption in the thick ascending limb of Henle's loop (TALH) resulting in marked ante- and postnatal salt wasting. In some of these patients mutations in the renal potassium channel ROMK (KCNJ1) have been found. We analyzed the electrophysiological function of five recently described ROMK channel mutations (V72E, D108H, P110L, A198T and V315G). In whole cell patch clamp recordings wildtype rat ROMK1 exhibited K+ currents of >1 nA at a membrane potential of 100 mV when transfected into COS-7 kidney cells. These currents were sensitive to external Ba2+ and internal Mg2+, which are typical features of the inwardly rectifying KIR channel. In contrast mutated ROMK1 cDNAs expressed either no or only infrequently small currents (<200 pA). Loss of tubular K+ channel function probably prevents apical membrane potassium recycling with secondary inhibition of Na-K-2Cl-cotransport in the TALH. We conclude that mutations in the potassium channel ROMK are the primary events causing renal salt wasting in a subset of patients with the antenatal variant of Bartter syndrome.

Adolescent↗
PubMed1993

[Antenatal form of Bartter's syndrome].

Six cases of tubular disorder of antenatal onset responsible for biological manifestations characteristic of Bartter syndrome and severe hypercalciuria are reported. In all six cases, severe hydramnios occurred during pregnancy between the 26th and 28th week after the last menstrual period. All six patients were born prematurely; gestational age ranged from 20 to 35 weeks. Major polyuria with dehydration occurred immediately after birth. The amounts of water and sodium needed to compensate urinary losses ranged from 280 to 370 ml/kg/day and 25 to 43 mmol/kg/d, respectively, during the first two postnatal months. Decreased serum potassium levels and increased plasma levels of renin and aldosterone were seen in all six patients. Increased urinary excretion of calcium was evidenced during the first postnatal week in three cases. Urinary calcium excretion in the six patients ranged from 15 to 30 mg/kg/d. Nephrocalcinosis developed in all six patients and two patients developed urinary lithiasis. One patient died at one month of age from necrotizing enteropathy. The five remaining patients gradually developed severe growth failure with measurements between 4 and 5.5 SDs below the mean. These five patients had evidence of hyperparathyroidism including increased serum levels of parathyroid hormone (5/5), increased serum alkaline phosphatase activity (4/5), and roentgenographic bone changes (1/5). Ionized calcium assays performed in three of the five patients disclosed low values (range 1.25-1.47 mmol/l; mean = 1.35; normal values = 1.42-1.62), although total serum calcium levels were normal or high (range 2.16-2.98 mmol/l; mean 2.61; normal values = 2.45-2.65) probably as a result of chronic dehydration.(ABSTRACT TRUNCATED AT 250 WORDS)

Aldosterone↗
PubMed1992

Alport syndrome: a genetic study of 31 families.

Thirty one families with Alport syndrome including 3 families with associated syndromes were studied. The location of the COL4A5 gene, responsible for the Alport syndrome, was determined by linkage analysis with eight probes of the Xq arm and by a radiation hybrid panel. Concordant data indicated the localization of the Alport gene between DXS17 and DXS11. Four deletions and one single base mutation of the COL4A5 gene were detected. Homogeneity tests failed to show any evidence of genetic heterogeneity superimposed on clinical heterogeneity for ophthalmic signs and end-stage renal disease age.

Adolescent↗
PubMed1992

Substitution of arginine for glycine 325 in the collagen alpha 5 (IV) chain associated with X-linked Alport syndrome: characterization of the mutation by direct sequencing of PCR-amplified lymphoblast cDNA fragments.

A large kindred with adult-type X-linked Alport syndrome was studied with regard to a defect in the recently described COL4A5 collagen gene. Southern blot analysis with COL4A5 cDNA probes showed loss of a MspI restriction site. Direct sequencing of cDNA amplified from lymphoblast mRNA demonstrated a single-base substitution converting a glycine codon to arginine at position 325 in the alpha 5 chain of type IV collagen. The triple-helical collagenous domain of alpha 5(IV), characterized by a Gly-X-Y repeat sequence, is interrupted 22 times by noncollagenous sequences. The mutation creates an additional interruption in the Gly-X-Y repeat motif, between interruptions 4 and 5. It is interesting that such glycine substitutions inside the COL1A1 or COL1A2 genes have been associated with many cases of osteogenesis imperfecta. This gly325-to-arg substitution presumably alters the triple-helix formation, and, in turn, modifies the ultrastructural and functional characteristics of the type IV collagen network inside the glomerular basement membrane.

Adult↗
PubMed1991

[Renal artery pathology and its therapeutic indications in the child].

Between September 1955 and January 1990, 94 pediatric patients were managed for renovascular hypertension caused by renal artery occlusive disease. Patients (50 boys and 44 girls) were aged 4 days to 17 years (median age: 7 years). At initial evaluation, 34 patients had symptoms of hypertensive encephalopathy or acute heart failure, 36 had moderate symptoms, and 24 were symptom-free. Sixty-five cases were classified on the basis of clinical, radiological, and histological features, as follows: neurofibromatosis (17), fibromuscular dysplasia (11), diffuse arterial calcified elastopathy (11), renal artery thrombosis (10), Williams syndrome (4), Takayashu disease (3), and miscellaneous diseases (9). In the 29 remaining patients, classification was based only on radiological features: causes included unilateral renal artery stenosis (15), bilateral renal artery stenosis with or without aortic stenosis (11), and miscellaneous disorders (3). Surgical treatment consisted in 47 renal revascularization, procedures (14 aortorenal bypasses, 8 aortorenal reimplantations, 9 anastomoses in the upper mesenteric arterial system, 7 autotransplantations, 4 resection-reanastomosis procedures, and 5 miscellaneous procedures). Renal revascularization failed in 15 cases (32%) (because of thrombosis in 14 cases and dehiscence in one). Residual or recurrent stenosis was seen in 7 arteries, whereas the anatomic result was satisfactory in 25 arteries (53%). Blood pressures returned to normal in 16 of 40 (40%) patients successfully treated by revascularization. An additional 25 patients recovered normal blood pressure values after primary nephrectomy (21), partial nephrectomy (4) or nephrectomy after failed renal revascularization.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗
PubMed1990

[Evaluation of new markers of bone metabolism in renal osteodystrophy in children].

Serum intact parathormone (PTH 1.84) and osteocalcin levels were evaluated as early markers for secondary hyperparathyroidism in a group of pediatric patient treated with chronic hemodialysis. PTH 1.84 levels which were more closely related with alkaline phosphatase levels than PTH 53.84 levels, allowed to identify a group of children without biologic or roentgenographic evidence of hyperparathyroidism and with a normal residual hormone level. PTH 1.84 levels seem to be a reliable indicator of parathormone secretion than conventional assays and may be used as a routine test for monitoring children under chronic hemodialysis. Conversely, the plasma osteocalcin level measured by radioimmunoassay was increased in all studied patients regardless of parathyroid status and seemed to be of little value for monitoring renal osteodystrophia. Lumbar vertebral plate bone density studies disclosed abnormalities of bone mineralization in half the children with renal failure. Dialyzed or non dialyzed. Patients with decreased bone mineralization presented, in most of cases, a history of previous steroid treatment. A group of children with very severe renal failure had increased bone mineralization. The interpretation of this abnormality remains to be determined.

Bone and Bones↗