An Infant Case of Transient Distal Renal Tubular Acidosis and Fanconi Syndrome Caused by Rotavirus Gastroenteritis.

We report an infant case of transient distal renal tubular acidosis and Fanconi syndrome caused by rotavirus gastroenteritis. A 10-month-old boy was admitted to the hospital because of frequent vomiting, lack of vitality, and dehydration. He was diagnosed with rotavirus gastroenteritis on account of his positive stool rotavirus antigen test. Although he presented with acidemia and severe mixed metabolic acidosis, he also had a urine pH of 6.0, indicating impaired urinary acidification. Therefore, he was diagnosed with distal renal tubular acidosis. On the third day of hospitalization, a relatively low %tubular reabsorption of phosphate level with hypophosphatemia, increased fractional excretion of uric acid with hypouricemia, and high urinary ß2-microglobulin levels were observed. Moreover, he was diagnosed with Fanconi syndrome on account of multiple proximal tubular dysfunctions. After remission of rotavirus gastroenteritis, the signs of renal tubular dysfunction improved. This was a case of rotavirus gastroenteritis-caused transient distal renal tubular acidosis and Fanconi syndrome. Severe metabolic acidosis resulted from anion-gap metabolic acidosis due to acute kidney injury by rotavirus gastroenteritis and normal anion-gap acidosis due to renal tubular acidosis. When renal tubular acidosis is associated with a disease that causes anion-gap metabolic acidosis, mixed metabolic acidosis occurs and becomes exacerbated. Furthermore, it is important to consider the complications of renal tubular acidosis in the case of severe metabolic acidosis.

Inhibition of platelet-derived growth factor pathway suppresses tubulointerstitial injury in renal congestion.

OBJECTIVE: Increased central venous pressure in congestive heart failure is responsible for renal dysfunction, which is mediated by renal venous congestion. Pericyte detachment from capillaries after renal congestion might trigger renal fibrogenesis via pericyte-myofibroblast transition (PMT). Platelet-derived growth factor receptors (PDGFRs), which are PMT indicators, were upregulated in our recently established renal congestion model. This study was designed to determine whether inhibition of the PDGFR pathway could suppress tubulointerstitial injury after renal congestion. METHODS: The inferior vena cava between the renal veins was ligated in male Sprague-Dawley rats, inducing congestion only in the left kidney. Imatinib mesylate or vehicle were injected intraperitoneally daily from 1 day before the operation. Three days after the surgery, the effect of imatinib was assessed by physiological, morphological and molecular methods. The inhibition of PDGFRs against transforming growth factor-ß1 (TGFB1)-induced fibrosis was also tested in human pericyte cell culture. RESULTS: Increased kidney weight and renal fibrosis were observed in the congested kidneys. Upstream inferior vena cava (IVC) pressure immediately increased to around 20 mmHg after IVC ligation in both the imatinib and saline groups. Although vasa recta dilatation and pericyte detachment under renal congestion were maintained, imatinib ameliorated the increased kidney weight and suppressed renal fibrosis around the vasa recta. TGFB1-induced elevation of fibrosis markers in human pericytes was suppressed by PDGFR inhibitors at the transcriptional level. CONCLUSION: The activation of the PDGFR pathway after renal congestion was responsible for renal congestion-induced fibrosis. This mechanism could be a candidate therapeutic target for renoprotection against renal congestion-induced tubulointerstitial injury.

Development of icterus gravis in a preterm infant with G71R UGT1A1 polymorphism.

BACKGROUND: Uridine diphosphate-glucuronosyltransferase (UGT) gene family is involved in the detoxification of biomaterials and drugs in the liver. Among the UGT gene family members, only UGT1A1 is involved in bilirubin conjugation. As a result, deficient UGT1A1 activity causes jaundice. One disease that is characterized by reduced UGT1A1 activity is Gilbert's syndrome. Two prevalent UGT1A1 polymorphisms responsible for Gilbert's syndrome have been identified: G71R in exon 1 and A(TA)7TAA in the TATA box of the promoter region. Recently, the G71R polymorphism has been associated with breastfeeding jaundice and neonatal hyperbilirubinemia in term infants. However, its association with jaundice in very low birth weight infants (VLBWIs) has never been reported. CASE PRESENTATION: The patient was a female born at 28 weeks, 4 days gestation with a birth weight of 1172 g. On day 21, intense yellowing of the skin and eyes was noted, and the patient's total bilirubin level was 23.7 mg/dL (her direct bilirubin level was 2.1 mg/dL). Therefore, an exchange transfusion was conducted. She had neither blood type incompatibility nor a family history of constitutional jaundice. Metabolic screens for amino and organic acids were negative. No elevation of any of the examined antibody titers was noted, and no evidence of an inflammatory reaction was observed. In addition, no hematological abnormalities were detected. The direct/indirect Coombs test, irregular antibody test and red blood cell antibody dissociation test were all negative, and her thyroid function was normal. We performed sequence analysis of the UGT1A1 gene after the patient's parents provided written informed consent. Exon 1 of the UGT1 gene on chromosome 2 was analyzed by direct sequencing. A heterozygous substitution from G to A (211G→A: G71R) in base 211 was noted. CONCLUSION: We speculated that this preterm infant with carrying the G71R polymorphism reduced UGT1A1 activity and developed severe jaundice that was likely triggered by factors such as breast feeding and medications. The polymorphism appears at some frequency among VLBWIs, which would necessitate adequate care of severe jaundice even after the acute phase.

Intestinal malrotation with suspected cow's milk allergy: a case report.

BACKGROUND: Intestinal malrotation is an incomplete rotation of the intestine. Failure to rotate leads to abnormalities in intestinal positioning and attachment that leave obstructing bands across the duodenum and a narrow pedicle for the midgut loop, thus making it susceptible to volvulus. One of the important differential diagnoses for malrotation is an allergy to cow's milk. Several studies have described infants with surgical gastrointestinal diseases and cow's milk allergy. However, to our knowledge, no study has reported infants with intestinal malrotation who have been symptomatic before surgery was performed and have been examined by allergen-specific lymphocyte stimulation test and food challenge tests with long-term follow-up. CASE PRESENTATION: The patient was a Japanese male born at 39 weeks of gestation. He was breast-fed and received commercial cow's milk supplementation starting the day of birth and was admitted to our hospital at 6 days of age due to bilious vomiting. Plain abdominal radiography showed a paucity of gas in the distal bowel. Because we demonstrated malpositioning of the intestine by barium enema, we repositioned the bowel in a normal position by laparotomy. The patient was re-started on only breast milk 2 days post surgery because we suspected the presence of a cow's milk allergy, and the results of an allergen-specific lymphocyte stimulation test showed a marked increase in lymphocyte response to kappa-casein. At 5 months of age, the patient was subjected to a cow's milk challenge test. After the patient began feeding on cow's milk, he had no symptoms and his laboratory investigations showed no abnormality. In addition, because the patient showed good weight gain and no symptoms with increased cow's milk intake after discharge, we concluded that the present case was not the result of a cow's milk allergy. At 1 year, the patient showed favorable growth and development, and serum allergy investigations revealed no reaction to cow's milk. CONCLUSION: When physicians encounter infants with surgical gastrointestinal disease, including intestinal malrotation, they should consider cow's milk allergy as a differential diagnosis or complication and should utilize food challenge tests for a definitive diagnosis.