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Biomedical subjects

B Gauthier

Publications and source records attributed to B Gauthier.

At least 19 recordsLinked to original sources
PubMed1992

Hypercalciuria in children with renal glycosuria: evidence of dual renal tubular reabsorptive defects.

During the past 5 years, we have identified idiopathic hypercalciuria in five of seven patients referred for evaluation of renal glycosuria between 1985 and 1991. The children, all boys, ranged in age from 6 to 12 years. Endocrine function was normal, and none of the patients had hyperparathyroidism, hypercalcemia, renal tubular acidosis, or other secondary causes of hypercalciuria. The calcium/creatinine ratio in a fasting urine specimen was elevated in all five children who had hypercalciuria, with a mean value (+/- SD) of 0.34 +/- 0.06 (normal, < 0.2). In one child who had renal colic with spontaneous passage of gravel-like material, the idiopathic hypercalciuria persisted after 1 week on a diet containing 2000 mg of sodium and 300 mg of calcium. On the basis of studies that examined the site along the nephron responsible for hypercalciuria in rats with streptozocin-induced diabetes, we speculate that in children with renal glycosuria, there is defective reabsorption of glucose and calcium in the straight portion of the proximal tubule or in the collecting duct. It is likely that a similar mechanism accounts for the idiopathic hypercalciuria in children with diabetes mellitus.

Absorption↗
PubMed1992

Clinical, cognitive, and neurophysiological effects of alprazolam in children and adolescents with overanxious and avoidant disorders.

In a double-blind, placebo-controlled study, the efficacy and safety of alprazolam was investigated in childhood and adolescent anxiety disorders. Thirty patients (mean, 12.6 years) diagnosed with overanxious or avoidant disorders participated in the study. Evaluations included clinical, laboratory, cognitive, and qualitative EEG measurements. On a clinical global rating, there was no statistical difference between alprazolam and placebo. Relative to baseline EEG, acute alprazolam administration increased beta power in the right occipital lead, and chronic administration increased beta power in both leads. Alprazolam was well tolerated, and adverse effects were few, mild, and transient.

Adolescent↗
PubMed1991

Inadequacy of captopril challenge test for diagnosing renovascular hypertension in children and adolescents.

A captopril challenge test (CCT) for renovascular disease in adults was described recently. We used it in 20 consecutive, untreated hypertensive children and adolescents. All had a normal urinalysis and glomerular filtration rate and non-diagnostic renal sonograms or intravenous urograms. Plasma renin activity (PRA) was measured before and 1 h after administration of captopril (0.76 +/- 0.17 mg/kg). The CCT was positive in 10 patients. Renal arteriograms were performed in 7 patients with a positive CCT and in 2 with a negative CCT. Renovascular disease was found in 4 patients, 1 of whom had a negative CCT. The PRA response to captopril was the same in patients with true- and the false-positive tests. The predictive value of the positive test was 43%. In conclusion, we did not find the CCT, as described for adults, to be of value in children and adolescents.

Adolescent↗
PubMed1991

Renal transplantation in children: an American view from the bridge.

Performance of renal transplants in children frequently necessitates transfer of patients from the care of a local pediatric nephrologist to a regional, tertiary care center that is specially equipped to carry out organ transplantation. This shift in institutional affiliation can be the cause of some difficulties in treating these complicated patients including: (1) disparities in the expected outcome of the renal transplant procedure; (2) co-ordination and timely completion of the pre-operative evaluation; (3) proper handling of transfers of patients between medical centers and inter-physician communication; (4) psychosocial pressures encountered by parents when their children are under the care of two teams of physicians. It is recognized that the relationship between the referring pediatric nephrologist and the transplant physician is paradigmatic of the association that develops between a general practitioner and a specialist. With this in mind, we offer some tentative suggestions on how to improve the therapeutic alliance between referring pediatric nephrologists and transplant surgeons, in the hope that this will improve the care of all pediatric transplant recipients.

Attitude of Health Personnel↗
PubMed1991

IgA nephropathy in a child with human immunodeficiency virus type 1 infection.

Infection with the human immunodeficiency virus type 1 (HIV-1) can cause a spectrum of renal disease, termed acquired immunodeficiency syndrome (AIDS) nephropathy. The most common clinical manifestations of kidney involvement in HIV-1-infected patients are proteinuria and/or nephrotic syndrome, and the histopathological pattern usually reveals focal segmental glomerulosclerosis. We describe an 8-year-old child with AIDS who presented with recurrent gross hematuria. A kidney biopsy demonstrated IgA nephropathy. This unique case indicates that the range of kidney disease in HIV-infected children may be broader than originally thought, and that these patients warrant a complete evaluation of any renal abnormality.

Biopsy↗
PubMed1990

The renal functional and structural consequences of corticosteroid and angiotensin-converting enzyme inhibitor therapy in chronic puromycin aminonucleoside nephropathy.

Glomerular diseases are characterized by increased urinary protein excretion. Treatment of this abnormality frequently involves administration of corticosteroids and angiotensin-converting enzyme inhibitors. There has been much recent interest in the potential impact of these drugs on progressive renal dysfunction, since they have opposing effects on intraglomerular hemodynamics. Therefore, we investigated the effect of methylprednisolone or captopril treatment on animals with chronic puromycin aminonucleoside nephropathy. In rats given a single injection of puromycin aminonucleoside, 15 mg/100 g body weight, both methylprednisolone and captopril significantly reduced proteinuria at 6 months [83 +/- 14 untreated (n = 7), 34 +/- 6 with methylprednisolone (n = 8), and 6 +/- 1 mg/24 h with captopril (n = 5), P less than 0.001]. Segmental glomerulosclerosis occurred with equal frequency in the untreated (7.8 +/- 2.3%) and methylprednisolone-treated rats (5.0 +/- 1.11%), but was significantly reduced by the administration of captopril (1.0 +/- 0.5%, P less than 0.001). We conclude that in chronic puromycin aminonucleoside nephropathy, treatment with corticosteroids reduces proteinuria without increasing the incidence of segmental glomerulosclerosis. Therapy with an angiotensin-converting enzyme inhibitor substantially decreases proteinuria and lessens the severity of glomerular scarring.

Adrenal Cortex Hormones↗
PubMed1990

Hypocalcemia and hypercalcitoninemia in critically ill children.

To study Ca metabolism in critically ill children, we measured ionized Ca (Ca2+), parathyroid hormone (PTH), calcitonin, 25 hydroxycholecalciferol (25[OH] D3), 1-25 dihydroxycholecalciferol (1-25[OH]2D3, and gastrin levels in critically ill children and in healthy controls. Patients were considered hypocalcemic if Ca2+ was less than 1.1 mmol/L. Six (14%) of 45 patients were hypocalcemic. Five hypocalcemic patients were studied and were found to have higher calcitonin levels than normocalcemic patients and healthy controls and higher PTH levels than healthy controls. 25(OH)D3 and 1-25(OH)2D3 were not significantly different in the three groups of patients. Gastrin levels were low in critically ill patients, whether or not they were hypocalcemic. We conclude that hypocalcemia occurs frequently in critically ill children. It is associated with raised levels of calcitonin and PTH. The mechanism for the increase in calcitonin is unknown.

Acute Disease↗
PubMed1990

Kearns-Sayre syndrome presenting as renal tubular acidosis.

Renal tubular acidosis and tetany were the 1st manifestations of Kearns-Sayre syndrome in a 5-year-old child. Subsequently, he developed progressive external ophthalmoplegia, ptosis, retinopathy, heart block, and endocrinopathy. There was a 7.5-kb deletion of mitochondrial DNA documented in muscle, kidney, skin fibroblasts, and leukocytes, providing evidence for a multisystem mitochondrial cytopathy.

Acidosis, Renal Tubular↗
PubMed1990

Acute interstitial nephritis in adolescents and young adults.

We have reviewed our experience with acute interstitial nephritis (AIN) in pediatric patients over the 3-year period from 1985 to 1988. We encountered 7 new cases of AIN in this interval and it was seen in 7% of kidney biopsies performed during this time of study. The clinical presentation was very nonspecific and included fever (100%), gastrointestinal complaints (57%) and rash (28%). Laboratory findings on admission included elevated erythrocyte sedimentation rate (100%), anemia (70%), pyuria (57%) and abnormal renal ultrasound (86%). Associated systemic diseases were observed in 4 patients. AIN was severe enough to necessitate treatment with hemodialysis in 42% of the cases. Corticosteroid therapy was used in 6 patients with a favorable response in all but 1 case. While 6/7 patients manifested complete recovery, 1 adolescent who may have had pre-existing renal disease had persistent chronic renal failure (estimated GFR, 25 l/min/1.73 m2). We have concluded that: (1) AIN is a relatively common disease in pediatric practice; (2) it can be severe enough to necessitate dialysis therapy, and (3) AIN often occurs in children with systemic disorders that may be associated with immunologic disorders.

Adolescent↗
PubMed1990

Hepatitis-B-associated glomerulonephritis: pathology, pathogenesis, and clinical course.

Hepatitis-B-associated glomerulonephritis (HBGN) is a distinct entity occurring frequently in hepatitis-B-prevalent areas of the world. The disease affects both adults and children who are chronic hepatitis-B-virus (HBV) carriers with or without a history of overt liver disease. The diagnosis is established by serologic evidence of HBV antigens/antibodies, presence of an immune complex glomerulonephritis, immunohistochemical localization of 1 or more HBV antigens, and pertinent clinical history, when available. In this study we present clinicopathologic and follow-up findings in 12 patients (7 children, 5 adults) with hepatitis-B-associated glomerulonephritis. Twelve patients provided 15 renal biopsies and 1 specimen of kidney tissue, obtained at autopsy; these were examined by light microscopy, electron microscopy, and immunohistochemical methods. Membranous glomerulonephritis (MGN) with or without mesangial proliferation was noted in 7 biopsies, mesangiocapillary (membranoproliferative) glomerulonephritis (MCGN) in 5 biopsies, and proliferative glomerulonephritis with or without membranous changes in 2 biopsies. Tubulointerstitial changes were minimal except in 3 adults, in whom they were attributable to arterionephrosclerosis. Ultrastructural findings included the presence of considerable amounts of focal or diffuse granular electron-dense deposits in the glomeruli, in the subepithelial, subendothelial, and mesangial locations, occasionally destroying or replacing the lamina densa of the basement membrane. Variable mesangial proliferation was also observed, with interposition, with focal irregular reduplication of the basement membranes and rare clusters of spherical particles, probably representing viral particles in the deposits. In addition, granular deposits along tubular basement membranes were seen in 1 case. The glomerular deposits stained for 2 or more immunoglobulins, the predominant one being IgG, and variably also for complement components (C3, C4 and C1q). Hepatitis B viral antigens (HBsAg, HBcAg, HBeAg) were demonstrated using acid elution techniques in the deposits in all biopsies where frozen tissue was available, singly or in a variety of combinations and intensities. There were deposits of IgG, C3, C1q, and HBsAg along the tubular basement membranes in 1 case. Follow-up biopsies in 2 cases, 2 and 5 years apart, showed a transformation from a diffuse MGN to MCGN with segmental membranous features. Follow-up biopsy after 3 years in the third patient, who went into clinical remission, revealed partially resolving glomerular lesions. Renal lesions secondary to chronic liver disease, parasitic diseases, certain tropical nephropathies, and lupus nephritis are some of the diseases that may morphologically resemble HBGN. Recognition and differentiation of HBGN from other entities may have significant prognostic and therapeutic implications.(ABSTRACT TRUNCATED AT 400 WORDS)

Adult↗
PubMed1989

Estimation of glomerular filtration rate in anorectic adolescents.

Severe malnutrition has been associated with a decrease in fat and lean body mass, as well as in renal function. This study was designed to evaluate the estimation of glomerular filtration rate (GFR, ml/min per 1.73 m2) in malnourished teenagers, by using the formula GFR = kL/Pcr (where L is body height, Pcr is plasma creatinine concentration and k is a proportionality constant relating muscle mass to body size that has been found to equal 0.7 in adolescent boys and 0.55 in girls). Body composition was estimated using anthropometric measurements and urinary creatinine excretion (UcrV). Malnourished female patients showed depletion of fat and muscle, whereas males had primarily decreased muscle mass. There was a good correlation (r = 0.74) between anthropometric [arm muscle volume (AMV)] and chemical UcrV estimates of muscle mass. However, our previously validated estimate of GFR did not give reliable results in this group of malnourished teenagers, probably because their muscle mass was so greatly altered by the severity of malnutrition. Therefore, we used anthropometric measurements and Pcr, to estimate GFR by multiple linear regression. The best prediction was obtained by using AMV/Pcr and the observed/expected (for age, height and sex) weight ratio (WR): GFR (ml/min) = 0.06 AMV/Pcr + 131 WR - 79, r = 0.82, n = 13. We confirm that malnutrition in adolescents is associated with decreased GFR and conclude that the resulting variability in body composition limits the possibility of estimating GFR from Pcr and height.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗
PubMed1989

A comparison of three nocturnal enuresis treatment methods.

To evaluate the efficacy of an operant approach that includes the bell and pad for the treatment of enuresis (Tangible Rewards with Fading), it was compared with an established operant method that includes the bell and pad (the Dry Bed method) and to a conventional Bell and Pad method. Although there were no overall statistically significant differences among the three methods, individual pairwise comparisons were of interest; the Dry Bed method had no advantage, but the Tangible Rewards with Fading method tended to have more patients reach a 14-day dryness criterion (p less than 0.10) and tended to have fewer patients relapse after treatment (p less than 0.08) than the Bell and Pad method.

Behavior Therapy↗
PubMed1989

Familial thin basement membrane nephropathy in children with asymptomatic microhematuria.

A review of 130 children with persistent microhematuria showed that the most common abnormality was a form of hereditary nephritis for wich we propose the term 'familial thin basement membrane nephropathy' (FTBMN). This lesion is not as severe as that of Alport's syndrome but carries a guarded prognosis. Family histories, urinalyses and audiograms systematically done on parents and other relatives show that FTBMN may be present in as many as 39% of children with persistent microhematuria and that careful family studies identify children likely to have this lesion.

Adolescent↗
PubMed1988

Platelet vasopressin levels in childhood idiopathic nephrotic syndrome.

Despite the importance of disturbances in plasma volume in nephrotic patients, the only clinically accepted measurement of this value in common use is plasma renin activity. We assessed the usefulness of plasma vasopressin levels as an index of plasma volume in patients with idiopathic nephrotic syndrome. However, since 80% to 90% of arginine vasopressin circulates bound to platelets, we measured vasopressin levels in platelet-rich and platelet-poor plasma. The nephrotic patients (n = 19) had significantly higher vasopressin levels in platelet-poor and platelet-rich plasma compared with controls (3.2 +/- 0.6 vs 1.0 +/- 0.3 pg/mL, and 10.4 +/- 3.6 vs 3.3 +/- 0.6 pg/mL. respectively). The percent binding of vasopressin to platelets was reduced in nephrotic patients compared with controls (50.2% +/- 6% vs 70.4% +/- 2.9%). The values for platelet-poor vasopressin, but not platelet-rich vasopressin, correlated significantly with the plasma renin activity (r = .83). We conclude that in nephrotic patients, platelet-poor vasopressin levels correlate with plasma renin activity and may provide a useful measure of minute-to-minute vasopressin release in response to changes in plasma volume.

Adolescent↗
PubMed1987

Parenteral calcitriol for treatment of severe renal osteodystrophy in children with chronic renal insufficiency.

Renal osteodystrophy is a common and incapacitating complication of chronic renal failure in children. Standard therapy with oral calcium supplements, phosphate binders, and vitamin D preparations is often inadequate to control progressive bone disease. We report the use of parenteral calcitriol therapy in two children, aged 2 and 15 years, respectively, with chronic renal failure. This treatment effectively suppressed secondary hyperparathyroidism in both patients, causing a nearly 50% reduction in circulating parathyroid hormone level and a parallel decline in serum alkaline phosphatase activity. In the younger patient, therapy was associated with healing of subperiosteal bone resorption and accelerated growth velocity. These findings indicate that parenteral administration of calcitriol may be an effective treatment option in some patients with refractory renal osteodystrophy and secondary hyperparathyroidism.

Administration, Oral↗