Biomedical subjects
Publications and source records attributed to A Vallo.
One case of hypophenylalaninemia during the dietary low phenylalanine treatment is presented. The general problem of dietary treatment from early ages is reviewed. The appearance of this iatrogenic disease despite adequate supply of this essential aminoacid is stressed. Authors recommend follow-up of these patients in a regional reference center with adecuate technology.
A 2-year-old girl presenting with features of both Bartter's syndrome and renal tubular acidosis was investigated. Hypokalemia, increased plasma renin activity in the absence of hypertension, insensitivity to the pressor effects of angiotensin and a histological picture of juxtaglomerular hyperplasia were characteristic of Bartter's syndrome, but an unusual finding was the presence of metabolic acidosis instead of alkalosis. Functional studies revealed a proximal tubular defect in sodium and bicarbonate reabsorption and a distal defect in sodium reabsorption, urinary acidification and concentrating mechanism. Indomethacin administration was followed by an excellent clinical response and improvement of most functional abnormalities. The defect in distal sodium reabsorption was, however, not corrected by prostaglandin inhibition, and could represent the primary event leading to potassium wasting and secondary hypersecretion of prostaglandins.
The case of a child affected with piridoxinresistant homocystinuria who developed early on the disease an aseptic thrombosis of intracraneal sinuses, of chronic evolution is presented. Pathogenesis and therapy of the thrombosis are discussed emphasizing the value of measures directed to avoid the aggregation of platelets.
Three unrelated infants with apparently distal RTA were investigated. Growth retardation, polyuria, nephrocalcinosis, inappropriately high urinary pH, and marked dependence of bicarbonate excretion on urinary flow were characteristic of the distal or classic form of RTA, but the urinary loss of bicarbonate at normal serum values exceeded that usually found in children or adults with this disorder. Renal tubular function was studied during hypotonic saline diuresis in the three patients and in seven healthy control infants of similar age. Fractional delivery of sodium to the distal nephron was significantly higher in the patients than in control subjects. Sodium transport at the diluting segment was not impaired. The results support the assumption that the bicarbonate wasting was the consequence of an increased delivery of this substance to an already impaired distal nephron and thus further inhibited the distal mechanisms of net acid excretion.
A 9-year-old girl presented with tetralogy of Fallot and moderate metabolic acidosis. Despite a Blalock's fistula there was evidence of chronic hypoxia with cyanosis, clubbing of fingers and toes and very elevated blood hematocrit values. Renal acidification and bicarbonate titration demonstrated the existence of proximal renal tubular acidosis: renal bicarbonate threshold was low (18 mmoles/1) and normal urinary acidificaiton was present at subthreshold serum bicarbonate levels. Following corrective heart surgery, blood acid-base values and renal reabsorption of bicarbonate became normal. A causal relationship between extracellular fluid volume expansion dependent on the high hematocrit and proximal renal tubular acidosis is suggested.
Ten two to ten weeks old children are presented with urinary tract infection and jaundice. In six cases "E. coli" was the causative organism. Laboratory data seemed to indicate that hemolisis was an important factor in the pathogenesis of jaundice. Treatment with appropriate antibiotics was favorable in all cases. Urinary tract infection with bacteriemia and jaundice is probably the most frequent cause of jaundice among children of two to ten weeks of age.
Renal function was investigated in a group of ten patients aged two months to eleven years, with chronic or recurrent urinary tract infection caused by different malformations of the urinary tract. The following tests were performed: endogenous creatinine clearance, maximal urinary concentrating ability, urinary acidification, maximal urinary diluting ability, free water clearance, index of fractional distal sodium delivery and index of distal tubular reabsorption of sodium. It is concluded that the follow-up of glomerular function by means of creatinine clearance and of tubular function by means of maximal concentrating ability consitute the most sensible way to detect renal functional impairment in children with chronic or recurrent pyelonephritis.
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The Wilms' tumor gene (WT1) encodes a protein that is believed to exert transcriptional and tumor-suppressor activities. Mutations in this gene have occasionally been associated with Wilms' tumor (<15% patients) and, more consistently, with three syndromes characterized by urogenital abnormalities (WAGR, Denys-Drash and Frasier syndromes). We report 17 years follow-up of a 29 year-old phenotypic female with 46,XY karyotype, gonadal dysgenesis and nephronophthisis in order to identify possible germline alterations of the WT1 gene. Frasier syndrome was suspected and confirmed by genetic analysis. Sequence analysis permitted the identification of an A40-->G mutation in position +5 in the donor splice site of intron 9. During surgery for streak gonads extirpation, a microscopic gonadoblastoma was found, a typical complication of Frasier syndrome.
Functional indices of distal acidification were assessed in five unrelated children with primary distal renal tubular acidosis. All patients were unable to lower urinary pH below 6.0 both during ammonium chloride-induced acidosis or after acute i.v. administration of furosemide. In these patients the urine minus blood Pco2 gradient failed to increase normally during acute sodium bicarbonate loading (mean +/- SEM: 5.8 +/- 2.0 mmHg), or after neutral phosphate administration (13 +/- 2.7 mmHg), despite adequate urinary concentrations or bicarbonate (72.2 +/- 14.6 mmol/L) and phosphate (25 +/- 2.3 mmol/L), respectively. They also failed to decrease urine pH below 5.5 with sodium sulfate (7.17 +/- 0.08), but urinary potassium excretion increased significantly. These results strongly suggest that the mechanism responsible for defective distal acidification is a failure of hydrogen ion secretion ("secretory' defect) and not an inability to establish a steep hydrogen ion gradient, as it was formerly believed.
Clinical and renal morphologic studies are reported in a 3 1/2 month old infant with congenital syphilis and nephrotic syndrome. Renal lesions were consistent with membranous proliferative glomerulonephritis, and the presence of glomerular deposits of IgM, C3, and of less intensity of IgE and fibrin, were demonstrated by means of immunofluorescence. These findings identify the renal lesion as an immune glomerulopathy. A therapeutic course of penicillin resulted in resolution of clinical manifestations without any evidence of persistent renal damage.
A three month old infant with hepatic cirrhosis of rapid instauration is presented. Diagnosis of acute tyrosinemia was suspected by clinical data and confirmed by the quantitiative determination of plasma amino acids and the peculiar histological characteristics of hepatic cirrhosis. Authors review briefly the pathogenesis, symptoms and treatment of the disease.