Yasuo Takekoshi

Free " small " and IgG-associated " large " hepatitis B e antigen in the serum and glomerular capillary walls of two patients with membranous glomerulonephritis.

Nephrotic syndrome developed in two children who carried hepatitis B virus. Both their serums contained hepatitis B surface antigen and hepatitis B e antigen (HBeAg). Two physicochemically and immunologically different categories of HBeAg activity were identified in their serums--i.e., small molecular (free) and large molecular (associated with IgG). Their kidney-biopsy specimens disclosed pathologic changes typical of membranous glomerulonephritis. By a fluorescent-antibody technic, HBeAg was found to be deposited in diffuse granular fashion, along glomerular capillary walls together with IgG and beta1C, but no deposition of hepatitis B surface antigen was detected. The presence of HBeAg in association with IgG both in the serum and in the kidneys of these patients suggests that HBeAg caused membranous glomerulonephritis by inducing the formation and deposition of immune complexes.

Strong association between membranous nephropathy and hepatitis-B surface antigenaemia in Japanese children.

Renal histology in 163 Japanese children, aged 3 to 15, with proteinuria and/or haematuria showed that 11 had membranous nephropathy (M.N) and the rest had various other renal diseases. Hepatitis-B-virus surface antigen (HBsAg) was identified, by a reversed passive haemagglutination method, in the serum of all the patients with M.N. but in only 4.6% of the patients with other renal diseases. 6 of the 11 mothers of the children with M.N. were positive for HBsAg, and 1 was positive for antibody to HBsAg (anti-HBs). These findings suggest that M.N. in Japanese children is mainly, if not exclusively, caused by hepatitis-B virus and that in most instances the virus is transmitted from mother to child.

Identification and immunohistochemical localization of macrophage migration inhibitory factor in human kidney

Macrophage migration inhibitory factor (MIF) was the first lymphokine identified in activated T‐lymphocytes. MIF can induce proinflammatory cytokines, such as interleukin‐1 and tumor necrosis factor‐α. In this study, we identified MIF expression in a tissue specimen of a normal portion of a nephrectomized human kidney by reverse transcription‐polymerase chain reaction (RT‐PCR) and Western blot analysis. Furthermore, immunohistochemical study using an anti‐human MIF polyclonal antibody demonstrated that MIF was mostly present in the renal tubule epithelial cells and, to a lesser extent, in Bowmans capsular epithelial cells. We also carried out immunohistochemistry on cultured human renal proximal tubule epithelial cells, which showed that MIF was present in the cytoplasm of the epithelial cells. These results suggest the possibility that MIF takes part in the mechanism of inflammation and immunological events in the human kidney.

Three Novel AVPR2 Mutations in Three Japanese Families with X-Linked Nephrogenic Diabetes Insipidus

We identified three novel mutations of the arginine vasopressin (AVP) V2 receptor (AVPR2) gene in Japanese families with X-linked congenital nephrogenic diabetes insipidus (NDI). In kindred #1 of siblings, a single base deletion of one out of three guanosines (nucleotides 786-788, 786delG) was detected. This deletion shifts the reading frame with an altered amino acid sequence and introduces a premature stop codon (TGA) at position 270. In kindred #2 of siblings and one unrelated additional patient (patient #3), point mutations that change the same Pro residue at codon 322 in the seventh transmembrane domain to either a Ser or His (P322S or P322H) were detected. This P322 residue is well conserved among rat V1 and V2 receptors, the human oxytocin receptor, and other G protein-coupled receptors, and is thought to be important for proper insertion of the receptor into the membrane. The AVPR2 mutations are heterogenous both in Japanese and Caucasians populations.

Renal tubular acidosis and skeletal demineralization in patients on long-term anticonvulsant therapy

Three children ranging from seven to 12 years of age from unrelated families were given long-term anticonvulsant therapy including acetazolamide (Diamox). These children had rickets and renal tubular acidosis. Investigations have suggested (1) secondary hyperparathyroidism due to hypocalcemia of rickets and (2) prolonged acetazolamide therapy were responsible for acidosis as a result of reduction of bicarbonate reabsorption in the kidney. A clear-cut recovery from acidosis and rickets was seen in two patients following medication with high doses of vitamin D, an oral supplement of phosphorus, and discontinuance of acetazolamide therapy.

Glomerular Deposition of C4 Cleavage Fragment (C4d) and C4-Binding Protein in Idiopathic Membranous Glomerulonephritis

Renal biopsies from 12 patients with idiopathic membranous glomerulonephritis (IMGN) were investigated by immunofluorescence microscopy for the localization of C4d and C4-binding protein (C4bp). Although Clq and C4 deposits were found in only 2 of 12 cases (16%), C4d and C4bp deposits were identified in 11 cases (92%) in close association with IgG deposits in the glomeruli. The results suggest that complement activation through the classical pathway usually occurs in IMGN. The detection of C4d and C4bp in the glomeruli appears to be a sensitive indicator of the classical pathway activation in IMGN.

4q33–qter deletion and absorptive hypercalciuria: Report of two unrelated girls

We report on two unrelated girls with multiple malformations, each of whom had a der(4)t(4;?)(q33;?) chromosome--an unbalanced translocation chromosome with deletion of the 4q33-qter segment and addition of a segment of an unknown chromosome. One of the two girls had asymptomatic kidney stones. Both had excess urinary calcium excretion (0.53 and 0.84 mg/mg creatinine, respectively), exaggerated excretion on oral calcium load, and reduced but excessive excretion on restricted calcium intake. The urinary calcium excretion of their parents was normal. Both girls were thus diagnosed to have sporadic absorptive hypercalciuria. It was deduced that the 4q33-qter segment contains the putative gene for absorptive hypercalciuria.

Urinary Excretion of Terminal Complement Complexes in Glomerular Disease

To evaluate renal terminal complement activation in patients with glomerular diseases, we measured terminal complement complexes (TCCs) in plasma and urine with sandwich enzyme-linked immunosorbent assay (ELISA) using a monoclonal antibody against a C9 neoepitope expressed on TCC and a polyclonal antihuman C7 antibody. TCCs were detectable in plasma but not in urine in most of normal controls. In plasma, TCC levels were elevated in 4 of 22 patients with lupus nephritis and in 6 of 12 with membranoproliferative glomerulonephritis. However all patients with IgA nephritis, focal glomerulosclerosis, idiopathic membranous nephritis and idiopathic minimal change nephrotic syndrome (MC) showed normal values. In urine, TCCs were detectable in almost all patients with heavy proteinuria (greater than or equal to 100 mg/ml) except MC. The TCCs present in urine were partially purified by gel filtration using Sepharose 6B and were found to contain C5, C6, C7, C8, C9 and S protein by ELISA. Although the molecular weight of TCC is similar to that of IgM, the fractional excretion rate of TCC was about 100 times higher than that of IgM. These results suggest that TCCs detectable in urine contain SC5b-9 complexes and are mostly of renal origin.

Proto-oncogene expression in human glomerular diseases

The expression of the protein products and mRNA of c‐fos, c‐myc, p53, and c‐raf was examined in normal renal tissues and biopsy specimens from 73 patients with various glomerular diseases. Immunofluorescent staining showed that there were cell nuclei stained for c‐Fos, c‐Myc, and p53, and cytoplasm positive for c‐Raf, in the glomeruli of patients with proliferative types of glomerulonephritis, including IgA nephritis and lupus nephritis, and in patients with focal glomerular sclerosis. Glomerular expression of c‐fos and c‐myc mRNA was detected by in situ hybridization. The number of proto‐oncogene‐positive glomerular cells was significantly higher in lupus nephritis, IgA nephritis, and focal segmental sclerosis, as compared with minimal change nephrotic syndrome and normal specimens. In IgA nephritis, the population of glomerular cells positive for c‐Fos and c‐Myc and the grade of c‐Raf immunoreactivity were significantly correlated with the proportion of proliferating cell nuclear antigen (PCNA)‐positive glomerular cells, with histological grading of mesangial hypercellularity and matrix increase, and with the magnitude of proteinuria. These data indicate that proto‐oncogene expression is associated with mesangial proliferation and matrix expansion in proliferative types of glomerulonephritis and in focal glomerular sclerosis.

Pseudohypoparathyroidism type II and anticonvulsant rickets.

A patient treated with anticonvulsants showed hypocalcemia and hyperphosphatemia in association with increased serum parathyroid hormone, reduced serum 25-hydroxy D3, diminished response in phosphorus excretion to exogenous parathyroid hormone and normal response in cyclic AMP excretion. Oral administration of Vitamin D3 resulted in normalization of serum 25-hydroxy D3, calcium, and phosphorus. At this stage, phosphorus excretion after parathyroid hormone returned to normal. These findings suggest that the patient had pseudohypoparathyroidism type II with anticonvulsant medication as a complicating factor.