Biomedical subjects

K Nitta

Publications and source records attributed to K Nitta.

At least 181 records · Page 10Linked to original sources

PubMed1994

[The early lesions of renal amyloidosis].

Two patients with minimal amyloid deposition in association with nephrotic syndrome are reported. Since the amyloid deposits in each renal biopsy specimen were inconspicuous, both were first thought to be minimal glomerular changes. A few widely scattered, silver-positive, epimembranous spicules were found on careful reexamination by light microscopy. Congo red stain and electron microscopy confirmed the presence of small glomerular amyloid deposits and amyloid fibrils. Furthermore, immuno-fluorescence microscopy showed partial IgA deposits in the mesangial area and capillary wall. We therefore urge careful examination to detect amyloid deposits of all kidney biopsy specimens of minor glomerular abnormalities, or glomerulonephritis with IgA deposits from elderly patients with nephrotic syndrome. Light microscopy of Congo-red-stained sections and electron microscopy of the fibrillar structure very useful for the detection of small amyloid deposits.

Adult↗

PubMed1994

[Association of cell cycle and protein kinase C with the expression of cytoskeletal protein in cultured rat mesangial cells].

We conducted a study to investigate whether expression of the contractile proteins in cultured rat mesangial cells (MC) was associated with the cell cycle and protein kinase C (PKC). When growth-arrested MC were stimulated with 100 nM phorbol myristate acetate (PMA) for 24 hours, an increased expression of smooth muscle alpha-actin and vimentin was detected by immunocytochemistry. A proportion of the S- and G2/M-phase in MC was increased in accordance with the enhanced expression of contractile proteins on flow cytometry. Immunoblot analysis revealed that 100 nM PMA stimulated expression of alpha-actin and vimentin as a single band. These results indicate that expression of contractile proteins, such as alpha-actin and vimentin, is dependent on the cell cycle and PKC, suggesting a phenotypic change in which MC assume smooth muscle cell characteristics.

Animals↗

PubMed1994

A case of primary glomerular fibrosis associated with the accumulation of type I and type III collagen.

A 49-year-old woman suffering from nephrotic syndrome (NS) was admitted for renal biopsy and treatment of NS. Light microscopy demonstrated that the glomerular capillary wall was markedly thickened with diffuse accumulation of periodic acid Schiff- and periodic acid methenamine-positive materials, leading to lobular accentuation of glomerular tufts. By electron microscopy, numerous collagenous fibers were observed in the mesangium and subenodothelial area. The fibers were peculiarly curved and frayed, as reported in nail-patella syndrome. These materials were thought to be type I and type III collagen as a result of immunohistochemical studies. No laboratory data or pathological findings were found to be compatible with previously described glomerulonephritis. The primary glomerular fibrosis in the present patient seemed to be a case of collagenofibrotic glomerulonephropathy.

Collagen↗

PubMed1994

Establishment and characterization of an immortalized bovine glomerular endothelial cell line.

Bovine subcultures (second passage) of glomerular endothelial cells (GEN) isolated from one-year-old kidney were successfully transfected by recombinant plasmids containing the simian virus (SV)-40 T antigen (Tag) using a lipofectin-mediated procedure. One cell clone was selected, propagated and characterized. This clone can be grown in RPMI 1640 medium supplemented with 10% fetal calf serum. The advantage of this cell line is the cultivation of bovine GEN without the addition of fibroblast growth factor or a coating of fibronectin or gelatin on the culture plate. More than 80 passages were achieved and the doubling time was 32 h. The Tag was easily identified in transfected-GEN by indirect immunofluorescence. These cells weakly expressed factor VIII-related antigen, slightly took up acetylated-low density lipoprotein and secreted a detectable amount of angiotensin-converting enzyme. Immunocytochemical staining for UAE-1 was also positive. Moreover, oncoproteins, such as Ki-67 and p53, were expressed in these cells. Cell cycle analysis by flow cytometry revealed that the percentages of G1, S, and G2/M stages in cycling transfected-GEN culture in RPMI 1640 medium supplemented with 10% fetal calf serum were 34%, 52.9%, and 13.1%, respectively. The conditioned medium from confluent transfected-GEN stimulated [3H]thymidine incorporation into glomerular mesangial cells. This cell line may provide a useful tool for examining modulators of mesangial cell growth. Thus this cell line is the first immortalized bovine GEN that retain the morphologic, phenotypic, and functional characteristics of bovine GEN.

Animals↗

PubMed1994

[Glomerular endothelial cell culture and its application].

Glomerular endothelial cells (GEN) have recently been cloned, cultivated and characterized. They have as same biological characteristics as expressed in endothelial cells derived from different sources. Because of the difficulties of cloning of GEN, we first transfected plasmid DNA containing large T antigen of SV-40 (NH-GEN1). Culture method of GEN and NH-GEN1 and its application are discussed.

Animals↗

PubMed1994

[Sensitivities to other antiviral drugs and thymidine kinase activity of aciclovir-resistant herpes simplex virus type 1].

Sensitivity tests of various antiviral drugs on aciclovir-resistant strains of herpes simplex virus type 1 (HSV-1) were done in vitro. Activity of thymidine kinase (TK) of the aciclovir-resistant strains was also investigated. A strain of HSV-1 isolated from a patient with herpes labialis was grown in Eagle's minimum essential medium containing 10(-6)M aciclovir (ACV) and passaged 20 times. Then ACV-resistant strains of HSV-1 were obtained. Sensitivity tests of 5 anti-herpetic agents (ACV, ganciclovir, carbocyclic oxetanocin G, (S)-9- (3-hydroxy-2-phosphonylmethoxypropyl)adenine ((S)-HPMPA), and adenine arabinoside (ara-A)) were done on these ACV-resistant strains. The ACV-resistant strains were resistant to ganciclovir and carbocyclic oxetanocin G, but they were sensitive to (S)-HPMPA and ara-A. These ACV-resistant strains showed no detectable TK activity.

Acyclovir↗

PubMed1994

Identification of GTP-binding proteins in human glomeruli.

The localization of GTP-binding proteins (G-proteins) in human glomeruli was examined using immunohistochemistry and immunoblotting. Immunohistochemical staining for G-protein subunits demonstrated the existence of Gs alpha, Gi alpha and Go alpha proteins in the glomeruli. Moreover, immunoblots further revealed Gs alpha (52 kD), Gi alpha 1/2 (40-41 kD), Gi alpha 3 (40 kD) and Go alpha (39 kD) in the glomerular membranes. The predominant subspecies of Gs was a 52-kD protein, and Go alpha was detectable in the smallest amounts of the G-protein subunits. However, immunoblots failed to demonstrate detectable amounts of G-proteins in cytosolic extracts. This is the first report that characterizes G-protein subunits in human glomeruli. Further study is required to determine the roles of G-proteins in signal transductions in human glomeruli.

GTP-Binding Proteins↗

PubMed1994

[Significance of membrane attack complex inhibitory factor expression in cultured human glomerular epithelial cells].

Membrane attack complex (MAC) inhibitory factor (MACIF) is a 20-kD membrane protein that inhibits MAC formation on homologous cells. Until recently, a functional role of MACIF had been demonstrated in erythrocytes. Therefore, we have focused on the fact that glomerular epithelial cells (GECs) are the primary target of MAC-mediated damage in rat Heymann's nephritis model of human membranous nephropathy. Using immunocytochemistry and western blotting we have shown that MACIF is expressed in cultured human GECs. Phosphatidyl-inositol (PI)-phospholipase C (PLC) reduced MACIF expression in these cells, suggesting that MACIF is a PI-linked membrane protein in GECs. In addition, we elucidated that MACIF protects GECs against complement-mediated lysis. These findings suggest that MACIF expressed on GECs plays an important role in the protection of GECs against complement mediated-cellular damage in vivo.

CD59 Antigens↗

PubMed1993

Agglutinins from aquatic insects--tumor cell agglutination activity.

Agglutinins were identified in whole body extracts of aquatic insects by means of murine tumor cell agglutination, using sarcoma 180 ascites, Ehrlich, and MM-46 cells. Screening revealed agglutinins in 5 of 10 of the larvae tested, and in 2 of 6 of the water-dwelling adult insects; Gerris paludum insularis and Gyrinus japonicus. Only the agglutinin from adult G. paludum also agglutinated human erythrocytes. An ascites tumor was converted into a solid form in vivo after administration of G. paludum agglutinin. The observation that these aquatic insect agglutinins preferentially agglutinate tumor cells has considerable implications in terms of anti-tumor effects such as inhibition of cell proliferation and metastasis.

Agglutination↗

PubMed1993

MRI appearances of calcified regions within intracranial tumours.

The MRI appearances of calcification within intracranial tumours was assessed by reviewing MR images of 11 calcified tumours documented by CT. The signal intensity of the calcified regions was varied and nonspecific on both T1- and T2-weighted images. They were seen as signal void exclusively on T2-weighted images in only 2 patients. Gadolinium enhancement of the calcified portion occurred in 7 of 10 patients. These findings reflect the presence of tumour parenchyma within the calcified region, as proved in 5 lesions examined histologically.

Adolescent↗

PubMed1993

CELSS nutrition system utilizing snails.

At the 40th IAF Congress in Malaga, a nutrition system for a lunar base CELSS was presented. A lunar base with a total of eight crew members was envisaged. In this paper, four species of plants--rice, soybean, lettuce and strawberry--were introduced to the system. These plants were sufficient to satisfy fundamental nutritional needs of the crew members. The supply of nutrition from plants and the human nutritional requirements could almost be balanced. Our study revealed that the necessary plant cultivation area per crew member would be nearly 40 m3 in the lunar base. The sources of nutrition considered in the study were energy, sugar, fat, amino acids, inorganic salt and vitamins; however, calcium, vitamin B2, vitamin A and sodium were found to be lacking. Therefore, a subsystem to supply these elements is of considerable value. In this paper, we report on a study for breeding snails and utilizing meat as food. Nutrients supplied from snails are shown to compensate for the above mentioned lacking elements. We evaluate the snail breeder and the associated food supply system as a subsystem of closed ecological life support system.

Animals↗

PubMed1993

Multiple sequence alignment by parallel simulated annealing.

We have developed simulated annealing algorithms to solve the problem of multiple sequence alignment. The algorithm was shown to give the optimal solution as confirmed by the rigorous dynamic programming algorithm for three-sequence alignment. To overcome long execution times for simulated annealing, we utilized a parallel computer. A sequential algorithm, a simple parallel algorithm and the temperature parallel algorithm were tested on a problem. The results were compared with the result obtained by a conventional tree-based algorithm where alignments were merged by two-way dynamic programming. Every annealing algorithm produced a better energy value than the conventional algorithm. The best energy value, which probably represents the optimal solution, was reached within a reasonable time by both of the parallel annealing algorithms. We consider the temperature parallel algorithm of simulated annealing to be the most suitable for finding the optimal multiple sequence alignment because the algorithm does not require any scheduling for optimization. The algorithm is also useful for refining multiple alignments obtained by other heuristic methods.

Algorithms↗

PubMed1993

Ribonuclease activity of sialic acid-binding lectin from Rana catesbeiana eggs.

Sialic acid-binding lectin (SBL) isolated from Rana catesbeiana eggs is a basic protein which agglutinates a large variety of tumour cells and has an amino acid sequence homologous to that of human angiogenin and pancreatic ribonuclease (RNase). Although SBL and angiogenin lack the Cys-65-Cys-72 disulphide bond of pancreatic RNase, the locations of the other three disulphide bonds are similar among the three molecules. SBL was found to exhibit RNase activity, as well as catalytic properties resembling those of bovine RNase A in some respects. For example, SBL hydrolyses poly(uridylic acid) and poly(cytidylic acid) as substrates, and prefers the former. RNase A and angiogenin are strongly inhibited by human placental RNase inhibitor, whereas the RNase activity and tumour cell agglutination activity of SBL are not affected by this inhibitor.

Amino Acid Sequence↗

PubMed1993

Comparative study of the stability of the folding intermediates of the calcium-binding lysozymes.

Unfolding profiles of two calcium-binding lysozymes, equine milk lysozyme and pigeon egg-white lysozyme, were obtained by circular dichroism and proton NMR measurements. Equine lysozyme unfolds through a stable molten globule intermediate. The molten globule of equine lysozyme was characterized as more ordered than that of bovine alpha-lactalbumin. On the other hand, pigeon lysozyme unfolds by a two-state mechanism and the intermediate could not be observed in guanidine or thermal unfolding, the same as with conventional non-calcium-binding lysozymes. Thus, from the point of view of the unfolding profile, equine lysozyme belongs to the group of alpha-lactalbumin, but pigeon lysozyme belongs to the conventional lysozyme group.

Animals↗

PubMed1993

Purification and characterization of Silurus asotus (catfish) roe lectin.

A rhamnose-binding lectin isolated from Silurus asotus (catfish) roe by DEAE-cellulose ion exchange and galactose-Sepharose affinity chromatographies predominantly agglutinated human type B and rabbit erythrocytes. S. asotus lectin (SAL) also agglutinated sarcoma 180 ascites carcinoma cells, but not AH109A cells. The most effective saccharide in hemagglutination inhibition assay was L-rhamnose. The monosaccharides possessing steric similarity to the hydroxyl group orientation at C2 and C4 of the pyranose ring structure of L-rhamnose, such as L-mannose and L-lyxose, were also effective. The molecular weight of SAL was determined to be 38000 by size exclusion chromatography on TSK gel G3000SW and 33000 by SDS-polyacrylamide gel electrophoresis under reducing conditions. SAL did not require a Ca2+ ion or free thiol group for its agglutination activity. The N-terminal 29 amino acid sequence was determined by a gas-phase sequencer as follows, ANMITCYGDVQKLHXETGLIIVKSXLYGR (X: not determined). It has no homology to the sequences of well known vertebrate lectins.

Agglutination↗

PubMed1993

Three rhamnose-binding lectins from Osmerus eperlanus mordax (olive rainbow smelt) roe.

Three rhamnose-binding lectins were purified from the roe of Osmerus eperlanus mordax (olive rainbow smelt) by affinity chromatography and ion-exchange chromatography. The apparent molecular weights of Osmerus eperlanus mordax lectin (OML) -1, -2 and -3 were 25000, 32000 and 26000, respectively, on sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) under reducing conditions. On native PAGE, these three lectins showed different migration patterns (Rm value; 0.37, 0.53 and 0.66, respectively). OMLs agglutinated rabbit and human type B erythrocytes and sarcoma 180 cells, but not human type A and O erythrocytes and AH109A cells. The most effective monosaccharide inhibitor was L-rhamnose. L-Mannose and D-galactose were also good inhibitors. Furthermore, OML-induced hemagglutination was inhibited more strongly by melibiose or raffinose rather than lactose or lactulose. Therefore, OMLs are L-rhamnose/alpha-D-galactosyl type lectins. OMLs did not require a detergent, when extracted from crude material, and Ca2+, Mg2+, EDTA and dithiothreitol were not necessary for the OML-induced hemagglutination activities. The OMLs had similar N-terminal amino acid sequences.

Amino Acid Sequence↗

PubMed1993

Purification and some properties of ribonuclease from Xenopus laevis eggs.

A 122 kDa RNase from eggs of Xenopus laevis was purified by sequential chromatography on Sephadex G-75, DEAE-cellulose, heparin-Sepharose and TSK gel G3000SW columns, and gave a single 60 kDa band on SDS-polyacrylamide gel electrophoresis under reducing and nonreducing conditions. The RNase composed of two 60 kDa subunits is able to recognize pyrimidine bases specifically. The pH optimum of the RNase was 7.5 in Tris-HCl buffer. The enzyme activity was abolished by treatment at 80 degrees C for 5 min and pH 2 or 12 for 1 h. Since egg lectins with RNase activity obtained from Rana catesbeiana and R. japonica and bovine pancreatic RNase A show about 30% protein homology and these three proteins are 12-14 kDa heat-stable RNases, [K. Titani, K. Takio, M. Kuwada, K. Nitta, F. Sakakibara, H. Kawauchi, G. Takayanagi and S. Hakomori, Biochemistry, 26, 2189 (1987); Y: Kamiya, F. Oyama, R. Oyama, F. Sakakibara, K. Nitta, H. Kawauchi, Y. Takayanagi and K. Titani, J. Biochem. (Tokyo), 108, 139 (1990)], the data suggest that the X. laevis egg RNase is a unique protein compared with RNases from not only amphibians, but also mammals.

Amino Acids↗

PubMed1993

The role of novel 30-kD protein in human podocytes: special relevance to proteinuria in glomerulonephritis.

A new monoclonal antibody (MAb) was raised against human glomerular components to investigate the possible existence of glomerular antigens reflecting cellular adaptation in glomerulonephritis. The MAb recognized a podocyte antigen as well as those expressed on renal arterial endothelial cells and smooth muscle cells by indirect immunofluorescence. An additional, but weaker immunoreaction was found in epithelial cells of the Bowman's capsule. This MAb recognized a 30-kD protein on western blotting of glomerular extracts under non-reducing and reducing conditions. Immunoperoxidase electron microscopy revealed that this antigen is present within the cytoplasm, but not on the cell membrane of the podocytes. Moreover, the antigen was found to be reduced in the glomeruli of patients with minimal change glomerulonephritis. These results suggest that the 30-kD protein is a novel protein, which we hypothesize is involved in maintenance of the structural and functional integrity of the podocytes. In addition, reduced expression of the 30-kD protein in the podocytes may be related to the increasing proteinuria in minimal change glomerulonephritis.

Epithelium↗