Biomedical subjects

I Kihara

Publications and source records attributed to I Kihara.

At least 19 recordsLinked to original sources

PubMed1995

Transient expression of type I collagen in glomeruli with anti-Thy-1 antibody-induced mesangial proliferative lesions.

Glomerular expression of extracellular matrices at the protein and mRNA levels was examined in rats with mesangial proliferative glomerulonephritis induced by the intravenous administration of a monoclonal anti-rat Thy-1 antibody. In close association with the mesangial proliferative lesion, type I collagen was immunostained at day 8 but not demonstrated at day 28 in the glomeruli of the kidneys. Type I collagen mRNA expression prominently increased in the nephritic glomeruli at day 4, prior to the appearance of type I collagen protein. In addition, fibronectin expression was also elevated in the diseased glomeruli at both the protein and mRNA levels. These results indicated that glomerular, probably mesangial cells, change their phenotypes during this disease, to synthesize abnormal extracellular matrices that lead to the progression of glomerular sclerosis.

Animals↗

PubMed1995

Vasopressin increases AQP-CD water channel in apical membrane of collecting duct cells in Brattleboro rats.

The effect of vasopressin on subcellular localization of AQP-CD and AQP3 water channels was examined in thirsted Brattleboro rats by immunohistochemistry and immunoelectron microscopy. AQP-CD was mainly present in the cytoplasm of the collecting duct cells in association with cytoplasmic vesicles but was sparse in the apical membrane in control vehicle-injected rats. In rats given vasopressin 15 min before death, the number of immunogold particles for AQP-CD in the apical membrane increased significantly (P < 0.002) from 1.8 +/- 0.2 to 10.0 +/- 0.4/microns with a significant decrease (P < 0.05) of cytoplasmic labeling from 32.6 +/- 6.4 to 24.6 +/- 5.6/microns 2, indicating that AQP-CD is the vasopressin-regulated water channel predicted by the "shuttle" hypothesis. In contrast, AQP3 was restricted to the basolateral membrane of the collecting duct cells, and the labeling density of AQP3 was unchanged by vasopressin treatment, indicating that AQP3 is constitutively expressed and may maintain high water permeability of the basolateral membrane.

Amino Acid Sequence↗

PubMed1995

Urinary excretion of podocalyxin indicates glomerular epithelial cell injuries in glomerulonephritis.

Immunofluorescent study of urine sediments was performed to detect glomerular epithelial cell injuries using specific monoclonal antibody against podocalyxin, a glycoprotein that is prominently expressed on glomerular epithelial cells. Three kinds of structures (casts, granules and cells) were stained in urine sediments from various glomerular diseases. The presence of podocalyxin in urines was confirmed by absorption test, immunoelectron microscopy and Western blotting. Podocalyxin was detected in the urinary sediments of patients with various forms of glomerulonephritis, particularly those with acute onset. The amount of their urinary excretion apparently indicates the degree of the glomerular epithelial cell injuries in glomerular diseases.

Adolescent↗

PubMed1995

Visceral epithelial cells in rat glomerular cell culture.

The purpose of this study was to identify and characterize visceral epithelial cells (VECs) of renal glomeruli in culture. Such cells have been described variably as regular, polygonal cells showing a high rate of replication and a cobblestone-like appearance at confluence and also as irregular, arborized and often multinucleated cells showing a very limited proliferative capacity. We examined early outgrowths from the glomeruli by immunofluorescence microscopy using antibodies specific for VECs (anti-podocalyxin(1A), anti-pp44 and 5-1-6), for endothelial cells (anti-von Willebrand factor (vWF) and RECA-1) and for mesangial cells (anti-Thy-1). 1A and anti-pp44 reacted with several types of irregular, arborized cells, but never with regular, polygonal cells. 5-1-6 did not react with any of the cells. Neither the 1A- nor anti-pp44-positive cells (1A/pp44(+) cells) stained with anti-vWF, RECA-1 or anti-Thy-1. However, all the 1A/pp44(+) cells expressed desmin and vimentin but not cytokeratin. These results show that the 1A/pp44(+) cells are derived from VECs, supporting the idea that most polygonal cells in glomerular cultures are of parietal epithelial origin.

Animals↗

PubMed1994

Functional characterization and cell immunolocalization of AQP-CD water channel in kidney collecting duct.

Vasopressin-regulated water permeability of the kidney collecting duct is a key component of the urine concentration machinery. Recently, a cDNA for AQP-CD, the vasopressin-regulated water channel, initially reported as WCH-CD, has been isolated (K. Fushimi, S. Uchida, Y. Hara, Y. Hirata, F. Marumo, and S. Sasaki. Nature Lond. 361: 549-552, 1993). AQP-CD was expressed in oocyte membrane using a Xenopus expression vector, and functional characteristics of AQP-CD were examined. Osmotic water permeability (Pf) of oocytes expressing AQP-CD was 138 +/- 19 microns/s (mean +/- SE), 12 times greater than the control (11 +/- 3 microns/s), 90% inhibited by 0.3 mM HgCl2, and weakly temperature dependent (energy of activation for Pf was 4.0 kcal/mol). Urea influx measured from 15-min [14C]urea uptake by oocytes injected with AQP-CD/expression vector 1 cRNA was 86 +/- 17% of the control. Two-electrode voltage-clamp experiments revealed insignificant ion conductance of AQP-CD. Immunoblots of membranes from rat kidney medulla and oocytes expressing AQP-CD using anti-AQP-CD COOH-terminal antibody showed a 29-kDa protein and 35- to 50-kDa high-molecular-mass forms. Immunohistochemistry showed apical and subapical localization of AQP-CD in the collecting duct principal cells. Our results indicated that AQP-CD is a 29-kDa protein, a selective water channel, distinct from a urea channel, and localized to the membranes of vasopressin-sensitive components in kidney collecting duct principal cells.

Amino Acid Sequence↗

PubMed1994

Water and protein permeability is regulated by the glomerular epithelial slit diaphragm.

The glomerular barriers to water and macromolecular movement were examined 2 and 24 h after the administration of a monoclonal antibody (mAb) specific to an antigen located on the epithelial slit diaphragm and the external aspect of the glomerular basement membrane. By micropuncture techniques 2 h after mAb administration, single-nephron GFR (SNGFR) and plasma flow were unchanged but the glomerular capillary hydrostatic pressure gradient and glomerular capillary hydrostatic pressure were increased and the glomerular ultrafiltration coefficient (LpA) decreased to values that were 50% of the normal control. There was no increase in urinary protein excretion at 2 h. However, at 24 h after mAb, nephron plasma flow (SNPF) and SNGFR increased and the glomerular ultrafiltration coefficient returned to values indistinguishable from the normal control. At 24 h, there was a marked increase in protein excretion. The administration of meclofenamate decreased values for SNGFR and SNPF to normal. Immunoglobulin G was exclusively bound to glomerular capillary walls in a linear or continuous fashion at 2 h, but in a discontinuous, granular pattern at 24 h. These studies suggest that after mAb, important limiting glomerular barriers for hydraulic conductivity and protein excretion reside on the epithelial aspect of the glomerular capillary basement membrane, specifically at the level of the slit diaphragm. Studies also suggest that alterations in glomerular capillary hydraulic conductivity can be effectively separated from increases in macromolecular permeability.

Animals↗

PubMed1992

Depletion of CD8 positive cells in nephrotoxic serum nephritis of WKY rats.

Following a small dose of nephrotoxic serum (NTS) WKY rats demonstrated crescentic glomerulonephritis, which was characterized by the early infiltration of CD8 positive cells in glomeruli. In vivo depletion of CD8 positive cells from WKY rats completely prevented proteinuria (4.6 +/- 4.8 mg/day vs. 105.3 +/- 11.6 mg/day on day 10; N = 19, P less than 0.001) and crescent formation (2.7 +/- 2.9% vs. 94.3 +/- 2.6%; P less than 0.001). Immunofluorescence revealed complete inhibition of the influx of CD8 positive cells and subsequent reduction of the infiltration of macrophages in the glomeruli. Glomerular binding of 125I-anti-rat glomerular basement membrane antibodies, host anti-rabbit IgG production and the C3 level in the circulation were the same as in the control. These data indicate that CD8 positive cells play a key role in glomerular injury and crescent formation. This model provides a useful system for studying the cellular mechanisms that lead to glomerular injury and subsequent crescent formation.

Animals↗

PubMed1991

Desmin-positive epithelial cells outgrowing from rat encapsulated glomeruli.

Decapsulated glomeruli, encapsulated glomeruli and tubular fragments were each selected and cultured in order to identify the origin of polygonal epithelial cells in glomerular outgrowths and to characterize them by double-label immunofluorescence microscopy using antibodies against cytoskeletal proteins. Polygonal cells outgrew from less than 1% of decapsulated glomeruli, 34.8 to 65.1% of encapsulated glomeruli and 62.4 to 79.7% of tubular fragments in culture. These data support the idea that polygonal cells in glomerular culture are derived mainly from parietal epithelial cells of Bowman's capsule but not visceral cells, and indicate that polygonal cells of tubular epithelial origin are also present. Polygonal cells from encapsulated glomeruli consisted of intensely vimentin-positive (IV) cells and weakly vimentin-positive (WV) ones. Most of the IV cells showed various degrees of staining with anti-desmin antibody, and some of them also expressed cytokeratins and alpha-smooth muscle actin. By contrast, all of the WV cells were stained with anti-cytokeratin antibody but not with anti-desmin antibody. Polygonal cells in cultures of tubular fragments were negative for desmin. These findings suggest that parietal cells express desmin in culture, even though they show no desmin staining in kidney sections.

Animals↗

PubMed1990

Isolation and characterization of proteoglycans synthesized by cultured mesangial cells.

Rat mesangial cells selected by long-term culture of glomeruli exhibited a hill and valley appearance in the confluent state and were stained with antibodies against vimentin and desmin, suggesting that they are smooth muscle-like mesangial cells. The glycoconjugates produced by the cells were metabolically labeled with [35S]sulfate and [3H]glucosamine and extracted with 4 M guanidine HCl containing 0.5% Triton X-100. The radiolabeled glycoconjugates were separated on DEAE-Sephacel and compared with those synthesized by glomeruli labeled in the same conditions. Of the three major sulfated glycoconjugates, sulfated glycoprotein (17% of the total 35S-labeled macromolecules), heparan sulfate proteoglycan (35%), and chondroitin sulfate proteoglycan (30%) synthesized by glomeruli, the cultured mesangial cells synthesized mainly chondroitin sulfate proteoglycan (more than 90%). After purification by CsCl density-gradient centrifugation, the chondroitin sulfate proteoglycan from the cell layer was separated on Bio-Gel A-5m into three molecular species with estimated Mr values of 230,000, 150,000, and 40,000-10,000, whereas that released into the medium consisted of a single species with an Mr of 135,000. In the beta-elimination reaction, the former two larger proteoglycans released chondroitin sulfate chains with Mr of an apparent 30,000 and the latter from the medium released the glycosaminoglycan chains with an Mr of 36,000. The Mr of the smallest proteoglycan from the cell layer was not significantly changed after beta-elimination, indicating that this species had only a small peptide, if any. Analysis with chondroitinase AC-II and ABC demonstrated that all the chondroitin sulfates were copolymers consisting of glucuronosyl-N-acetylgalactosamine (65-74%) having sulfate groups at position 4 (53-57%) or positions 4 and 6 (10-14%) of hexosamine moieties and iduronosyl-N-acetylgalactosamine (21-26%) having sulfate groups at position 4 (17-23%) or positions 4 and 6 (about 3%) of hexosamine moieties; namely chondroitin sulfate H type. These characteristics of the chondroitin sulfate H proteoglycans synthesized by the cultured mesangial cells were very similar to those of the proteoglycans synthesized by glomeruli. Thus, we conclude that most, if not all, of the glomerular chondroitin sulfate proteoglycans are synthesized by mesangial cells. The cultured mesangial cells were also found to synthesize hyaluronic acid at a similar level to chondroitin sulfate proteoglycan. Based on the characteristics of this glycosaminoglycan, we discuss the possible role of hyaluronic acid produced by mesangial cells.

Animals↗

PubMed1990

Variable expression of desmin in rat glomerular epithelial cells.

The presence of desmin, regarded as a marker of myogenic cells, in glomerular epithelial cells (GECs) of the kidney was studied in four strains of rat (SHR, Lewis, Fischer 344, WKA) by immunofluorescence microscopy and immunoelectron microscopy. Some of the GECs were stained with both monoclonal and polyclonal anti-desmin antibodies. The frequency of desmin-positive cells among GECs varied between glomeruli in each of the strains and also differed between the four strains. Most GECs in WKA rats contained desmin, whereas few did so in SHR rats. Lewis and Fischer 344 rats showed amounts of GEC desmin staining intermediate between those of SHR and WKA rats. In every strain, desmin-specific immunofluorescence in GECs increased with aging. In aminonucleoside nephrosis, GECs showed extremely enhanced desmin staining in parallel with urinary protein excretion. This heterogeneous distribution and changes observed for desmin were not shown for vimentin. On the basis of the above findings, the correlation between the presence of desmin in GECs and glomerular epithelial damage is discussed.

Aging↗

PubMed1989

The role of polymorphonuclear leukocytes in rat chronic serum sickness-type nephritis.

In order to investigate the role of polymorphonuclear leukocytes (PMN) in the distribution of antigen in various organs and in the development of nephritis, chronic serum sickness-type nephritis was induced in both anti-rat PMN rabbit serum (APS)-treated and normal rabbit serum (NRS)-treated rats by preimmunization with bovine serum albumin (BSA) and subsequent daily intravenous administration of BSA for 4 weeks. Kinetic studies using radiolabeled BSA showed that accumulation of BSA after the first intravenous administration was reduced by APS treatment in the liver, lungs and spleen and increased in the circulation, but was not affected in the kidneys and glomeruli. Histological studies supported the above findings. After 4 weeks of BSA administration, the BSA accumulation in the kidneys and glomeruli was significantly less in APS-treated rats than in NRS-treated ones, while amounts of BSA in the circulation and other organs were not different between the two groups. Furthermore, APS treatment reduced proteinuria, PMN infiltration and IC deposition in the glomeruli. These observations indicate that PMN play a partial role in IC deposition in the glomerular capillary walls and subsequent destruction of glomerular permeability in chronic serum sickness-type nephritis.

Animals↗

PubMed1988

Serial study of phagocytic function in rat bovine serum albumin (BSA) nephritis.

We have examined the in-vitro role of polymorphonuclear leucocytes (PMNs) and macrophages in the degradation of immune complexes (ICs) at various points during the induction of rat bovine serum albumin (BSA) nephritis. Two types of experiments have been used. In one set (experiment A) preformed 125I-BSA-anti-BSA complexes (which consisted of heterologous (rabbit) antibodies) were incubated with peritoneal macrophages and PMNs from normal and nephritic rats at 37 degrees C for between 1 h and 24 h and the degradation rates of ICs were studied. In the other set (experiment B), homologous ICs prepared from antibodies derived from the sera of nephritic rats were examined using macrophages and PMNs from normal rats. In experiment A, the degradation of heterologous ICs by macrophages was decreased but degradation by PMNs was not decreased if the assays were performed 8 or 9 weeks after injection. Degradation by both macrophages and by PMNs was increased at weeks 10 and 11. In experiment B, the degradation of homologous ICs from the nephritic rats was increased markedly at week 9 and a relationship was observed between both the degradation and antibody titre and the value of the antigen binding capacity of 33% (ABC-33) during the course of nephritis. There was no difference between PMNs and macrophages in their ability to degrade homologous ICs from the nephritic rats.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗

PubMed1986

Identification and quantitation of cells that process immune complexes in nephritic rats induced with bovine serum albumin.

A light microscopic autoradiography was used to determine which cell types positively disposed of the daily circulating immune complexes produced in rats with experimental immune complex glomerulonephritis. Our results indicated that polymorphonuclear leucocytes (PMNs) remove large quantities of immune complexes in the livers, spleens, and lungs of these rats. Semiquantitative autoradiography indicated further that the function of mononuclear phagocyte system decreased late in the course of glomerulonephritis; whereas, in compensation, the role of PMNs appeared to increase. Our data uncovered a significant role for PMNs in the disposition of immune complexes during the induction of experimental immune complex nephritis.

Animals↗

PubMed1986

Bovine serum albumin (BSA) nephritis in rats. IV. A sequential evaluation of mononuclear phagocyte system (MPS) function.

A clearance kinetic study of intravenously administered 125I-labeled aggregated human IgG (125I-AHIgG) from the circulation and its distribution in various organs was performed weekly during the course in a model of experimental immune complex glomerulonephritis which was induced in rats immunized 8 weeks previously with 6 times a week administration of 2 mg of bovine serum albumin (BSA) for 4 weeks from week 8 to 12. The removal rates of the injected 125I-AHIgG from the circulation were retarded in nonproteinuric rats of week 9 and 10, at almost every checked point (p-value was less than 0.01). The clearance in those rats with severe proteinuria returned to the level of the control and of rats in week 8. The distribution of 125I-AHIgG in the liver 4 hours after the administration revealed a considerable decrease in non-overt proteinuric rats of weeks 9, 10, and 11. A similar tendency of decreasing depositions of the radioactivity was shown in the spleen at each 4 hours. In contrast, the uptakes in the kidney and lung at the final week of 12 were larger. Delayed clearance from the circulation and a decreasing handle of the injected macromolecule in the liver and possibly in the spleen may suggest the presence of some impairment of the MPS function in the course of this experimental glomerulonephritis.

Animals↗

PubMed1986

Immunoelectron microscopic demonstration of Thy-1 antigen on the surfaces of mesangial cells in the rat glomerulus.

Mesangial cells of F344 rats degenerated and then disappeared within 2 days after the intravenous administration of rabbit antirat thymocyte serum (ATS). Rabbit IgG and rat C3 were identified in the mesangium in the rat glomeruli. To establish the glomerular binding site of ATS administered intravenously into rats, one kidney of each rat given ATS intravenously 12 h earlier was perfused ex vivo through the renal artery with peroxidase-labeled antirabbit IgG followed by sequential glutaraldehyde and diaminobenzidine perfusions to minimize the ultrastructural damage. The other kidney was removed before the perfusion for histologic study to examine the glomerular injury. The rabbit IgG identified by peroxidase-reaction product was present diffusely in the glomerular mesangium when viewed by light microscopy and exclusively on the surfaces of most mesangial cells by electron microscopy. Immunofluorescence microscopy showed rabbit IgG essentially in the mesangium, and electron microscopy revealed the degeneration of mesangial cells in the kidneys that had been removed before the surgical perfusion. However, no histological abnormalities were found in the kidneys from control rats given ATS absorbed with rat thymocytes. The present study showed that the intravenous administration of ATS into rats induced the extensive mesangial cell damage by the binding of ATS to Thy-1 antigens on the mesangial cells.

Animals↗

PubMed1986

Rat bovine serum albumin (BSA) nephritis. VI. The influence of chemically altered antigen.

Bovine serum albumin (BSA) used to incite chronic serum sickness glomerulonephritis in rats was chemically modified to study the effect of antigenic alteration. The BSA was used in its native form (n-BSA) as well as anionic (a-BSA), cationic (c-BSA) or glycosylated (g-BSA) forms. Spontaneously hypertensive rats (SHR) preimmunized 8 weeks earlier received daily intravenous injections of the respective BSA preparations for the ensuing 3 weeks. Histological examination of their kidneys revealed that c-BSA given for 2 weeks induced a severe diffuse proliferative glomerulonephritis and profound proteinuria. Electron-dense deposits localized preferentially in the subepithelial spaces of renal glomeruli from these rats, but a few in the mesangia. Quite differently, rats receiving n-BSA or g-BSA developed a less severe form of glomerulonephritis even after 3 weeks of injections. Besides the massive mesangial deposits, the subepithelial deposits were conspicuous in the glomeruli from rats given g-BSA for 2 weeks, but deposition in glomerular capillaries was rare in rats given n-BSA for the same duration. In contrast, the administration of a-BSA resulted in minimal abnormalities visible by light microscopy and a few immune deposits in the mesangia even at the third week. The antibody response in rats given c-BSA or a-BSA was apparently different from n-BSA treated rats. The present study shows the important role of the antigen's electric charge in the pathogenesis of proliferative glomerulonephritis. The foregoing results also foster our proposal that the carbohydrate content of the antigen influences the development of this renal disease.

Animals↗

PubMed1985

Granulocyte adhesion to nephritic glomeruli through recognition of activated C4 and C3 in immune deposits.

Sections of rat kidney with bovine serum albumin nephritis were incubated either with a single component of complement or with several components in sequence and then reacted with granulocytes. The average number of granulocytes bound to a nephritic glomerulus was elevated in sections incubated with C4 or C3 and increases were most significant when C14, C142 or C1423 were incubated.

Animals↗

PubMed1985

In vitro characteristics of rat mesangial cells in comparison with aortic smooth muscle cells and dermal fibroblasts.

Rat glomerular mesangial cells were cultured and their antigens were compared with those of aortic vascular smooth muscle cells and dermal fibroblasts. Glomeruli, aortic, and dermal explants were cultured for 3 weeks and subcultured in the same conditions. These cultured cells were evaluated by indirect immunofluorescence studies using antibodies against Thy-1 antigen, desmin, and chicken gizzard actin. Most of mesangial cells were positive for Thy-1, desmin, and actin. On the other hand, fibroblasts were negative for desmin, and smooth muscle cells stained Thy-1 scarcely, and were negative for desmin. In the latter two cells, actin-positive fibrils were thinner and fainter than mesangial cells. These results indicated that mesangial cells could be distinguished in vitro from vascular smooth cells and fibroblasts by immunofluorescence microscopy.

Actins↗