Sigeo Suzuki

Radiation Induction of Germline Mutation at a Hypervariable Mouse Minisatellite Locus

Paternal 60Co gamma-irradiation was tested for the induction of germline mutation at the mouse hypervariable minisatellite locus, Ms6hm. Male C3H/HeN mice were exposed to 3 Gy 60Co gamma-ray and mated with C57BL/6N females. Matings were made at 1-7, 15-21 and 71-77 days post-treatment to test spermatozoa, spermatids and spermatogonia stages. Reciprocal crosses were also made with irradiated C57BL/6N males. Southern analysis was carried out on DNA from parents and F1 mice. The paternal mutation frequencies per gamete of the Ms6hm locus were 8.3, 13, 28 and 15% for the C3H/HeN control, exposed spermatozoa, spermatids and spermatogonia stages, respectively. The paternal mutation frequencies per gamete were 7.7% for the C57BL/6N control and 13% for the C57BL/6N exposed spermatozoa stage. The increase in the paternal germline mutation frequency was statistically significant for C3H/HeN spermatids irradiation (p < 0.005). The induced mutation frequencies were of the order of 10(-1), and was too high to be accounted for by the direct action of radiation on the locus. These results suggest the presence of a previously unexpected mechanism of radiation induction of germline mutation. In addition, we demonstrate that the hypervariable minisatellite locus can serve as a sensitive monitor for genetic damages to germline cells.

Clinicopathological features and the prognosis of IgA nephropathy in Japanese children on long-term observation.

AIMS Clinicopathological features were investigated to clarify the ultimate prognosis and prognostic indicators for patients with IgA nephropathy in Japanese children. METHODS We evaluated the outcomes of 181 patients in whom IgA nephropathy was diagnosed before the age of 15 years since September 1979 and followed-up at least for three years with regard to clinical data at the onset of symptoms and renal histologic data. RESULTS After mean follow-up of 7.3 years from onset, 91 patients of 181 (50.3%) were in clinical remission at the last examination, 24 (13.2%) had isolated hematuria, 59 (32.6%) had hematuria and proteinuria. Eighteen of 59 (9.9%) had proteinuria more than 1 g per 24 hours. Hypertension was observed in 12 cases and 7 (3.9%) developed end-stage renal disease. Except 7, no patient had reduced renal function and elevated serum creatinine at the final follow-up. Predicted renal survival rate from onset was 92.3% at 10 years and 89.1% at 20 years. In multivariable analysis, age at onset and chronic changes of tubulointerstitium were associated with poor outcome. CONCLUSIONS Of 181 children with IgA nephropathy, 50% regressed, remaining 46% had hematuria and/or proteinuria and 4% of patients lapsed into end-stage renal disease. Our results indicate that childhood IgA nephropathy has a benign course and the risk for end-stage renal disease is lower than that of adults. Age at onset and tubulointerstitial lesions were the strong predictors of a progressive course of childhood IgA nephropathy.

Changes in Platelet Calcium Concentration by Thromboxane A2 Stimulation in Patients with Nephrotic Syndrome of Childhood

In order to examine the intracellular thromboxane A2 (TXA2) signal transduction system in platelets of patients with nephrotic syndrome, we measured the levels of TXA2 metabolites in urine and blood and platelet calcium ion level as a result of STA2, an analog of STA2 (9,11-dimethylmethano-11,12-methano-TXA2) stimulation, and obtained the following results: (1) In pediatric patients with nephrotic syndrome, urinary thromboxane B2 (TXB2) and 11-dehydro-TXB2 excretion were signficantly higher in the onset and relapse groups compared to the remission and control groups. (2) The blood 11-dehydro-TXB2 level in the onset group was significantly higher than those in the remission and control groups. (3) Platelet calcium concentrations due to STA2 stimulation were significantly increased in the onset, relapse and remission groups compared to the control group. These findings suggest activation of the TXA2 signal transduction system in platelets of pediatric patients with nephrotic syndrome.

Bucillamine-induced nephropathy in a child with juvenile rheumatoid arthritis and Kartagener's syndrome

The patient had suffered from swelling and pain bilaterally in the ankle and wrist joints and continued fever at 9 years of age in 1993. He was admitted to a hospital and was diagnosed with JRA and treated with combination of a nonsteroid anti-inflammatory drug (ibuprofen), methotrexate (MTX) and prednisolone. In September 1994, MTX was discontinued and bucillamine (50 mg/day) was prescribed. After 2.5 months, urinalysis revealed proteinuria. Bucillamineinduced renal injury was suspected. Bucillamine was discontinued, but proteinuria persisted. In May 1995, he was referred and admitted to our hospital. On admission, his ankle and wrist joints exhibited contracture bilaterally. Results of laboratory investigation were notable for a platelet count of 52.8 × 104/mm3, C-reactive protein (CRP) level of 1.58 mg/dL and erythrocyte sedimentation rate (ESR) of 28 mm/h. The third component of complement (C3), C4 and 50% hemolyzing dose of complement (CH50) were within normal range, antinuclear antibody was negative and rheumatoid factor was 8 U. Urinalysis revealed proteinuria (210 mg/dL) without hematuria, but with granular casts. The clinical course is shown in Fig. l. Proteinuria was 1.4 g/day and renal function was normal. Chest X-ray revealed situs inversus, with dextrocardia, right aortic arch and a bubble in the stomach below the right hypochondrium. Computerized tomography of the chest and head revealed bronchiectasis and maxillary and sphenoid sinusitis. We diagnosed Kartagener’s syndrome, on the basis of the situs inversus, bronchiectasis and chronic sinusitis. A renal biopsy was performed. On immunofluorescence microscopic examination (IF), the specimen contained six glomeruli; two glomeruli contained linear depositions of IgG along segmental glomerular capillary walls and a little deposition of C3. In four glomeruli examined, no depositions of immunoglobulin or complement were found. In 29 other glomeruli examined, no mesangial cell proliferation or increase in matrix was found. In four of these 29 glomeruli, light microscopy (LM) with Azan stain revealed subepithelial deposits in focal segmental glomeruli (Fig. 2). In two of six glomeruli, subepithelial deposits in glomerular basement membrane (GBM) were observed on electron microscopy (EM). We therefore diagnosed focal membranous glomerulonephropathy (MGN) induced by bucillamine. Pediatrics International (2000) 42, 316–318

Effect of Sairei-to on Prostaglandin E2-lnduced Phosphatidylinositol Breakdown in Aminonucleoside Nephrotic Rat

We describe the effects of Sairei-to, a Chinese herbal medicine, on aminonucleoside-induced nephrotic rats (ANNR), and analyze the urinary excretion of protein and phosphatidylinositol (PI) turnover via prostaglandin E2 (PGE2) receptors in isolated glomeruli. Sairei-to suppressed urinary excretion of protein and PGE2 in ANNR, and inhibited acceleration of PI turnover in isolated nephrotic glomeruli. The affected responsiveness of the PI turnover system to PGE2 in a nephrotic state was presumed to be normalized by Sairei-to. These findings suggest that Sairei-to restores abnormal changes in the PI turnover system in ANNR kidneys, and thereby inhibit excretion of protein into the urine.

Membranoproliferative glomerulonephritis associated with hereditary deficiency of the 4th component of complement.

A 10-year-old female patient was found positive for urine protein and occult blood on Japanese school urinary screening. Examination of the blood was normal except low values of the complement system with CH50 13.5 U/ml, C3 45 mg/dl and C4 3 mg/dl. Renal biopsy demonstrated a focal membranoproliferative glomerulonephritis (MPGN). As for the activity of each component of the complement in the early stage of the disease, the C4 activity was markedly declined and the activity of classical pathway component was also decreased, but the activity of alternative pathway component was normal. On the HLA examination, the patient demonstrated a C4 double null haplotype (C4A2, Q0, BQ0 phenotype). A null C4 gene at both the C4A and C4B loci was found in her mother, aunt and grandfather on the mothers side and C4B null allele in her father and her grandmother on the mothers side. The development of the disease is found in 1 case and not in the other, although both have the genetic defect and the mechanism by which the complement is activated remains unknown. Thus, there appear to be many subjects to be studied as to the relationship between the defect of C4 gene and immune competence.