Ja Wook Koo

Localization of Tamm-Horsfall Protein and Osteopontin in a Rat Nephrolithiasis Model

The possibility of more than one urinary protein being simultaneously associated with calcium oxalate (CaOx) crystallization in vivo was investigated by examining the localization of Tamm-Horsfall protein (THP) and osteopontin (Opn) in a rat model of nephrolithiasis. CaOx crystal deposits were induced in male Sprague-Dawley rats by feeding 0.75% ethylene glycol in drinking water. THP and Opn were localized on kidney sections by immunoperoxidase technique, using specific polyclonal antibodies. When only occasional crystal deposits were seen in the kidney, THP showed a similar to normal pattern of distribution, with positive staining in the thick ascending limbs of the loop of Henle. Opn was localized in some nephrons in the thin limb of loop of Henle and on the papillary surface in the calyceal fornix. In contrast, in samples with a significantly increased number of deposits in the kidneys, the staining for both THP and Opn was strikingly enhanced and altered, with positive staining around the crystals as well as abnormal localization in the papilla. Interestingly, the occurrence of Opn was, however, more consistent than that of THP. This is a first study showing that in this nephrolithiasis model, normal localization of THP and Opn is altered and they are closely and concurrently associated with crystal deposits in vivo.

Iron Absorption in Patients with Chronic Uremia on Maintenance Hemodialysis and in Healthy Volunteers Measured with a Simple Oral Iron Load Test

Gastrointestinal iron absorption was measured by an oral iron load test in patients with uremia on maintenance hemodialysis (n = 19), with iron overload (n = 9), iron deficiency (n = 10) and in healthy volunteers (n = 9). After an overnight fast, serum iron was measured before, and 1, 2, 4 and 6 h after administration of 100 mg ferrous chloride. Bone marrow iron was assessed after staining with Prussian blue. The study shows that iron absorption is impaired in uremic patients. Even uremic subjects with iron deficiency absorbed significantly less than normal subjects. Patients with iron overload and uremia absorbed even less, showing that the iron status of the patient influences absorption also in uremia.

Association of Angiotensin I Converting Enzyme Gene Polymorphism with Reflux Nephropathy in Children

Deletion polymorphism of angiotensin I converting enzyme (ACE) gene has been studied as a risk factor in various cardiovascular diseases and chronic nephropathies. Perturbation of local and systemic renin-angiotensin systems is one of the possible mechanisms of the progression of reflux nephropathy. In this study, the implication of ACE gene polymorphism in renal scarring and deterioration of renal function was analyzed in 66 children with vesicoureteral reflux. The genotype for the polymorphism was determined by PCR, and renal scar was identified by 99mTc-DMSA renal scan. The allelic frequency of the deletion polymorphism showed no significant difference either between patients with normal renal function and those with decreased renal function or between patients with renal scar and those without. We conclude that deletion polymorphism of ACE gene, as an independent variable, is not associated with reflux nephropathy in children with vesicoureteral reflux.

Heat Shock Protein 72/73 in Normal and Diseased Kidneys

The induction of heat shock (stress) proteins (HSP) is a response by cells due to a variety of physical, chemical, and infectious agents. They have a significant role as cytoprotectants, in the regulation of cellular functions, and in the recovery after sublethal injury. Using antibody to mammalian HSP 72/73, we have performed an immunohistological study of human renal tissue in normal and diseased states, including idiopathic nephrotic syndrome, proliferative and crescentic glomerulonephritis, and interstitial nephritis. A significant increase of HSP expression was noted in certain segments of the tubule in acute interstitial nephritis and in glomerulonephritis accompanied by active interstitial inflammation. A possible role by the inflammatory mediators in the induction of HSP in those cases is suggested.

Recurrent Hypokalemic Muscle Weakness as an Initial Manifestation of Wilson’s Disease

A 24-year-old man had several episodes of hypokalemic muscle weakness of undetermined etiology since the age of 13 years. Wilson’s disease (WD) was not diagnosed until the age of 18 when wing-beating

Familial renal glucosuria: a clinicogenetic study of 23 additional cases

BackgroundFamilial renal glucosuria (FRG) is an inherited renal tubular disorder characterized by persistent isolated glucosuria in the absence of hyperglycemia that is caused by mutations in the sodium-glucose cotransporter SGLT2 coding gene, SLC5A2.ObjectiveWe conducted molecular and phenotype analyses of a cohort of 23 unrelated Korean children with FRG.MethodsMutational analysis of the SLC5A2 gene was conducted in this multicenter study organized by the Korean Society of Pediatric Nephrology.ResultsA total of 21 different SLC5A2 mutations were detected, including 19 novel mutations. All patients had at least one mutated allele; ten patients had homozygous or compound heterozygous mutations and 13 patients had a single heterozygous mutation. Most mutations were private. Patients with two mutations were diagnosed earlier with larger amounts of urinary glucose excretion than patients with single mutations. Pedigree analysis data were consistent with the inheritance of a codominant trait with incomplete penetrance.ConclusionsThese findings extend the allelic heterogeneity in FRG and confirm previous observations of inheritance and genotype–phenotype correlation in patients with this disease.

Hospitalizations in Dialysis End-Stage Renal Failure Patients

The cost of treating end-stage renal failure (ESRF) patients includes not only the cost of dialysis and related medications but also the cost of hospitalizing these patients. This study examines the h

X-linked recessive nephrogenic diabetes insipidus: a clinico-genetic study.

Abstract A retrospective genotype and phenotype analysis of X-linked congenital nephrogenic diabetes insipidus (NDI) was conducted on a nationwide cohort of 25 (24 male, 1 female) Korean children with AVPR2 gene mutations, comparing non-truncating and truncating mutations. In an analysis of male patients, the median age at diagnosis was 0.9 years old. At a median follow-up of 5.4 years, urinary tract dilatations were evident in 62% of patients and their median glomerular filtration rate was 72 mL/min/1.73 m2. Weights and heights were under the 3rd percentile in 22% and 33% of patients, respectively. One patient had low intelligence quotient and another developed end-stage renal disease. No statistically significant genotype-phenotype correlation was found between non-truncating and truncating mutations. One patient was female; she was analyzed separately because inactivation and mosaicism of the X chromosome may influence clinical manifestations in female patients. Current unsatisfactory long-term outcome of congenital NDI necessitates a novel therapeutic strategy.

Intravenous fluid prescription practices among pediatric residents in Korea

Purpose Recent studies have established the association between hypotonic fluids administration and hospital-acquired hyponatremia in children. The present paper investigated the pattern of current practice in intravenous fluid prescription among Korean pediatric residents, to underscore the need for updated education. Methods A survey-based analysis was carried out. Pediatric residents at six university hospitals in Korea completed a survey consisting of four questions. Each question proposed a unique scenario in which the respondents had to prescribe either a hypotonic or an isotonic fluid for the patient. Results Ninety-one responses were collected and analyzed. In three of the four scenarios, a significant majority prescribed the hypotonic fluids (98.9%, 85.7%, and 69.2%, respectively). Notably, 69.2% of the respondents selected the hypotonic fluids for postoperative management. Almost all (96.7%) selected the isotonic fluids for hydration therapy. Conclusion In the given scenarios, the majority of Korean pediatric residents would prescribe a hypotonic fluid, except for initial hydration. The current state of pediatric fluid management, notably, heightens the risk of hospital-acquired hyponatremia. Updated clinical practice education on intravenous fluid prescription, therefore, is urgently required.

Comparison of plasma erythropoietin concentrations and iron status in hemodialyzed patients not requiring and requiring rHuEpo therapy.

Fifty patients treated with chronic hemodialysis (HD) were observed for 1 year. 24 of them (48%) did not require treatment with recombinant human erythropoietin (rHuEpo) (group I) because the permanent hemoglobin (Hb) concentration was > 5.9 mmol/l (9.5 g/dl), hematocrit > 30%. The remaining 26 patients (group II) permanently or periodically required rHuEpo treatment. After 6 months of initial observation and after 6 months of clinical study we made a comparison of endogenous erythropoietin (Epo) and iron status in two groups of patients. Patients not requiring treatment with rHuEpo had statistically significant higher Epo concentration and lower iron reserves than patients on rHuEpo treatment. We did not find significant differences in Hb, albumin and creatinine between patients in both groups. Hb concentration did not correlate with the level of Epo, serum creatinine, transferrin saturation, ferritin, iron reserves and time of dialysis therapy in both groups. In both groups we found a significant negative correlation between the concentration of Epo and iron stores. Our results indicate that in patients on HD treatment, plasma Epo level appears to depend either directly or indirectly on iron status.