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Biomedical subjects

M Kotani

Publications and source records attributed to M Kotani.

At least 73 records · Page 4Linked to original sources
PubMed1993

A decreased number of primordial germ cells and the small numbers and reduced sizes of germinal granules in the periodic albino mutant of Xenopus laevis.

Light and electron microscopy were used to examine the cause of the small number of primordial germ cells (PGCs) that were unexpectedly found in periodic albino (a(p)/a(p)) tadpoles of Xenopus laevis. The observations revealed that the volumes of germ plasm were not significantly different between a(p)/a(p) and wild-type eggs and that the germ plasm of ap/ap eggs contained a smaller number of germinal granules than are present in wild-type eggs and the granules were also smaller than in the wild-type eggs. It was concluded that the number of PGCs might be primarily determined by the number and size of germinal granules.

Albinism↗
PubMed1993

Differential distribution of major gangliosides in rat central nervous system detected by specific monoclonal antibodies.

We investigated the localization of major gangliosides in adult rat brain by an immunofluorescence technique with mouse monoclonal antibodies (MAbs). Five MAbs (GMB16, GMR17, GGR12, GMR5 and GMR13) that specifically recognize gangliosides GM1, GD1a, GD1b, GT1b and GQ1b, respectively, were used. We have found that there is a cell type-specific expression of the ganglioside in the rat central nervous system. In cerebellar cortex, GM1 was expressed in myelin and some glial cells. GD1a was detected exclusively in the molecular layer. GD1b and GQ1b were present restrictedly on the granular layer; GD1b was detected on the surface of the granular cell bodies, whereas GQ1b was present in the cerebellar glomerulus. GT1b was distributed intensely in both the molecular layer and the granular layer. In cerebral cortex, GM1 was detected in some glial cells. Dense staining was limited to the white matter. GD1a was distributed in layers I, II/III and Va, and the upper part of layer VI, whereas GQ1b was localized in layers IV and Vb, and the lower part of layer VI. GD1b was detected beneath layer III. GT1b appeared to be distributed throughout all layers. In other regions, such as hippocampal formation and spinal cord, the expression of the ganglioside was also highly localized to a specific cell type and layer.

Animals↗
PubMed1993

Generation of a monoclonal antibody specific for ganglioside GM4: evidence for GM4 expression on astrocytes in chicken cerebellum.

We established a murine monoclonal antibody (MAb) specific for ganglioside GM4 by immunizing C3H/HeN mice with chemically synthesized GM4 adsorbed to Salmonella minnesota, followed by fusion with mouse myeloma cells. The MAb, designated as AMR10, was shown to exhibit high binding specificity, reacting only with the ganglioside GM4 used for immunization and native GM4 from human brain. We determined the distribution of GM4 in adult chicken cerebellum by means of the immunofluorescence technique with the MAb. Our study revealed that GM4 expression was associated with astrocytes in the granular layer and the white matter, but not with myelin in any layers of the chicken cerebellar cortex.

Animals↗
PubMed1993

Characterization of ganglioside expression in human melanoma cells: immunological and biochemical analysis.

The expression of N-glycolylneuraminic acid (NeuGc)-containing gangliosides in human melanoma cells grown both in culture and as xenografts in athymic (nu/nu) mice was analyzed extensively with specific mouse monoclonal antibodies (MAbs). Three MAbs (GMR8, GMR14, and GMR3) specific for GM3(NeuGc), GM2(NeuGc), and GD3(NeuGc-NeuGc-), respectively, were used. Significant differences were observed in the ganglioside compositions between the cultured cells in vitro and the tumors grown in vivo. The major difference was that the cells cultured in serum-free medium did not express any NeuGc-containing gangliosides, whereas those grown in nude mice expressed a number of NeuGc-containing gangliosides, namely GM3(NeuGc), GM2(NeuGc), GD3(NeuAc-NeuGc-), GD3(NeuGc-NeuAc-), and GD3(NeuGc-NeuGc-). The structures of these gangliosides were also determined chemically. No activity of CMP-NeuAc hydroxylase was demonstrated either in the melanoma cells cultured in vitro or in those grown in nude mice, suggesting that these cells incorporated NeuGc-containing glycoconjugates from the mouse sera and converted them to other NeuGc-containing gangliosides. The mouse sera contained only GM2(NeuGc), but not the other NeuGc-containing gangliosides or any NeuAc-containing gangliosides.

Animals↗
PubMed1993

Generation of monoclonal antibodies to the rabbit interleukin-2 receptor alpha chain (CD25) and its distribution in HTLV-1-transformed rabbit T cells.

Rabbits can be infected with human retroviruses such as human T-cell leukemia virus-1 (HTLV-1) and human immunodeficiency virus (HIV), and provide useful animal models to study retroviral diseases such as adult T-cell leukemia and HIV. Previously we have succeeded in generating monoclonal antibodies (mAbs) against rabbit CD4, CD5 and CD11a antigens. To make this animal species more amenable to cellular and molecular studies, we have attempted to extend the panel of mAbs against rabbit CD antigens. Here we report on the generation of three neutralizing mAbs against interleukin-2 receptor alpha chain (IL-2R alpha) (CD25), Kei-alpha 1 (IgG2b), Kei-alpha 2 (IgG2a) and Kei-alpha 3 (IgG1). They specifically recognize the rabbit Mr 55,000 IL-2 binding protein, IL-2R alpha, and completely inhibit both high- and low-affinity IL-2 binding to F648b cells that express IL-2R alpha as well as IL-2R beta. The use of mAb Kei-alpha 1 confirmed that the rabbit IL-2R alpha is not only a low-affinity IL-2R on its own but also an essential component of high-affinity IL-2R as found in other animal species, and that rabbit activated T cells including HTLV-1-transformed cell lines express high levels of the IL-2R alpha. Together with mAbs against various rabbit CD antigens that we reported previously, these neutralizing mAbs to IL-2R alpha will be valuable for studies of human retrovirus infections, such as those induced by HTLV-1 or HIV, in rabbits.

Animals↗
PubMed1993

Immunofluorescence imaging diagnosis of Fabry heterozygotes using confocal laser scanning microscopy.

An immunofluorometric method was developed for the semiquantitative determination of trihexosylceramide in cultured fibroblasts from Fabry disease patients, using a laser scanning confocal imaging system. The accumulated glycolipid was detected as granular inclusions in the cells. Heterozygote identification was achieved both by counting of immunoreactive cells and by measuring the relative fluorescence intensity with a digital imaging system.

Adult↗
PubMed1993

Magnetometric evaluation of the effects of gallium arsenide on the clearance and relaxation of iron particles.

Intratracheal instillation of GaAs suspension has been histopathologically shown to induce a diffuse pulmonary response. In the present study, magnetometry was used to evaluate the effects of intratracheally instilled GaAs on the behavior of externally magnetized iron particles instilled in rabbit lung. Magnetometric evaluation of the effects of GaAs in rabbits dosed with 30 mg or 300 mg/animal showed significant decreased relaxation of iron particles at 1, 3, 7, 14, 21 and 28 days following instillation compared with the controls. Relaxation indicates a rapid decrease of remanent magnetic field following magnetization of the lungs due to random rotation of phagocytized iron particles in macrophages. Clearance of the iron particles was measured by serial determinations of the remanent magnetic field at the end of magnetization estimated from relaxation curves. Clearance was significantly impaired in rabbits exposed to both doses of GaAs at 14, 21 and 28 days after instillation. Dose-effect relationships were observed in both cases. Histological examination of lungs instilled with these doses indicated active phagocytosis of GaAs and iron particles by alveolar macrophages.

Animals↗
PubMed1992

Generation of one set of monoclonal antibodies specific for a-pathway ganglio-series gangliosides.

We established five murine monoclonal antibodies (MAbs) specific for a-pathway ganglio-series gangliosides by immunizing C3H/HeN mice with these purified gangliosides adsorbed to Salmonella minnesota, followed by fusion with mouse myeloma cells. The binding specificities of these MAbs were determined by enzyme-linked immunosorbent assay and immunostaining on thin-layer chromatogram. These five MAbs, designated GMR6, GMB28, GMB16, GMR17, and GMR11 reacted strongly with the gangliosides GM3, GM2, GM1, GD1a, and GT1a, respectively, that were used as immunogens. Three MAbs, GMB28 (anti-GM2), GMB16 (anti-GM1), and GMR11 (anti-GT1a) showed highly restricted binding specificities, reacting only with the immunizing ganglioside. None of the other various authentic gangliosides or neutral glycolipids was recognized. On the other hand, the other two MAbs, GMR6 (anti-GM3) and GMR17 (anti-GD1a) exhibited broader specificities. MAb GMR6 cross-reacted with GM4, GM1b, GD1a, GT1b, and IV3NeuAc alpha-nLc4Cer. MAb GMR17 also reacted with GM1b and GT1b. Neither GMR6 nor GMR17 reacted with other gangliosides or neutral glycolipids tested. Using these MAbs, we determined the expression of these gangliosides, especially GM1, GD1a, and GT1a on mouse, rat and human leukemia cells. GM1 and GD1a were expressed on some leukemia cells, whereas GT1a was not detected in these cells.

Animals↗
PubMed1992

Generation of one set of monoclonal antibodies specific for b-pathway ganglio-series gangliosides.

We established six murine monoclonal antibodies (MAbs) specific for b-pathway ganglio-series gangliosides by immunizing C3H/HeN mice with these purified gangliosides adsorbed to Salmonella minnesota mutant R595. The binding specificities of these MAbs were determined by an enzyme-linked immunosorbent assay and immunostaining on thin-layer chromatogram. These six MAbs, designated GGB19, GMR2, GMR7, GGR12, GMR5, and GGR13 reacted strongly with the gangliosides GD3, O-Ac-GD3, GD2, GD1b, GT1b, and GQ1b, respectively, that were used as immunogens. All these MAbs except GGB19 showed highly restricted binding specificities, reacting only with the immunizing ganglioside. None of other various authentic gangliosides or neutral glycolipids were recognized. On the other hand, MAb GGB19 exhibited a broader specificity, cross-reacting weakly with O-Ac-GD3, GQ1b, and GT1a, but not with other gangliosides or neutral glycolipids. Using these MAbs, we determined the expression of these gangliosides, especially GD1b, GT1b, and GQ1b on mouse, rat, and human leukemia cells. GD1b was expressed on rat leukemia cells, but not on mouse and human leukemia cells tested. Neither GT1b nor GQ1b was detected in these cell lines.

Animals↗
PubMed1992

Oestrogen retards the development of spontaneous thymomas in BUF/Mna rats.

BUF/Mna rats develop spontaneous thymomas with nearly 100% incidence in both sexes. While the thymomas in males develop from around 9 months of age, those in females start from 13-15 months of age. To clarify the mechanism of the delay of thymomagenesis in females, the effect of sex hormones on the development of thymomas was examined after either gonadectomy or oestrogen treatment. Prepubertal ovariectomy accelerated the thymoma development in females, whereas orchiectomy did not affect it. An intraperitoneal injection of oestriol (20 mg) into males at 2 months of age remarkably diminished the thymic weight to about one-tenth of age-matched controls at 16 months of age. These results suggest that oestrogen can actually retard the onset of thymoma in spite of genetic control of its incidence. However, oestrogen did not cause thymic involution when it was injected into rats over 9 months of age. Immunohistochemically, there seemed to be no distinct difference in distribution of oestrogen-receptor-bearing epithelial cells between thymomas and 2- to 3-month-old thymuses. The oestrogen sensitivity of the thymus might be destined to be lost, as the thymic epithelial cells start neoplastic changes with the impairment of oestrogen-receptor function.

Age Factors↗
PubMed1992

A study of mast cells in autoimmune NZB/W F1 mice: possible relationship between mast cells and increased vascular permeability in the thymus of NZB/W F1 mice.

We examined the possible relationship between thymic mast cells and increased vascular permeability in the thymus of autoimmune NZB/W F1 mice. Light-microscopic observation of tissue sections showed that non-autoimmune BDF1 mast cells increased with age. In contrast, autoimmune NZB/W F1 mast cells did not increase in the thymic parenchyma at the age of 9 weeks. However, NZB/W F1 mast cells resumed the age-associated increase from the age of 12 weeks and exceeded the number of BDF1 mast cells at the age of 30 weeks. Blood histamine levels of 9-week-old NZB/W F1 mice were higher than those of BDF1 mice of comparable age. Furthermore, peritoneal mast cells of NZB/W F1 mice were more sensitive to compound 48/80 than those of BDF1 mice. Increased blood histamine levels of NZB/W F1 mice seem to be due to the enhanced histamine release from mast cells. These results suggest a possible correlation between the high histamine levels by degranulation of mast cells and increased vascular permeability in the thymus of NZB/W F1 mice.

Age Factors↗
PubMed1991

Characterization of the rat leukocyte integrin, CD11/CD18, by the use of LFA-1 subunit-specific monoclonal antibodies.

We have attempted to characterize the rat leukocyte integrin, CD11/CD18, by the use of newly generated monoclonal antibodies (mAb) WT.1 (anti-CD11a) and WT.3 (anti-CD18) in conjunction with an mAb, OX42, reactive with a rat integrin-like molecule, with respect to the biochemistry, cellular distribution and function. The conclusion that the mAb WT.1 and WT.3 specifically recognize the rat CD11a and CD18, respectively, was based on: (a) their ability to inhibit homotypic aggregation of splenic concanavalin A (Con A) blasts; (b) sodium dodecyl sulfate-polyacrylamide gel electrophoretic analysis of the antigens recognized; (c) their ability to inhibit binding of Con A blasts to the purified ligand, namely the ICAM-1 antigen and (d) their blocking abilities in mixed leukocyte reaction. In the rat, CD18 has an apparent molecular mass of 95-100 kDa and can associate with at least three distinct alpha subunits of 160-170 kDa (CD11a), 140-150 kDa and 120-130 kDa. The latter two are precipitated by OX42 from M phi but not from unstimulated lymphocytes. They presumably represent the rat CD11b and CD11c, respectively. Rat thymocytes, PBL, thoracic duct lymphocytes, monocytes and neutrophils expressed differential levels of CD11a and CD18. Peritoneal M phi showed virtually no CD11a expression, although CD18 was expressed at levels similar to those seen on blood monocytes, showing an interesting pattern of LFA-1 expression regulation in this cell lineage. Both WT.1 (anti-CD11a) and WT.3 (anti-CD18) apparently recognize a "low-affinity" as well as a "high-affinity" form of LFA-1 and do not discriminate between the two.

Animals↗
PubMed1991

Molecular mechanisms underlying lymphocyte recirculation. II. Differential regulation of LFA-1 in the interaction between lymphocytes and high endothelial cells.

Although it has been suggested that LFA-1 is one of the important molecules mediating interaction between lymphocytes and high endothelial (HE) cells, the implication was based on the observation that lymphocyte binding to high endothelial venules in frozen lymph node sections was partially inhibited by anti-LFA-1 monoclonal antibody at 4 degrees C. However, it has previously been unequivocally demonstrated that LFA-1 molecule is unable to function at this low temperature. To assess the actual involvement of LFA-1 in lymphocyte-HE cell interaction at body temperature, we examined effects of newly developed anti-rat LFA-1 and anti-rat ICAM-1 monoclonal antibody on binding of resting or activated lymphocytes to a rat HE cell line at 37 degrees C. We found that (a) LFA-1/ICAM-1-independent pathway was predominant in the interaction between resting lymphocytes and HE cells, indicating that LFA-1 functions little, if any, in the interaction and (b) lymphocyte triggering through CD3 significantly increased binding inducing a LFA-1/ICAM-1-dependent pathway, whereas phorbol 12-myristate 13-acetate stimulation also enhanced lymphocyte binding but inducing a LFA-1-dependent/ICAM-1-independent pathway. In both cases no apparent alteration in LFA-1 expression was observed, suggesting that the increase in lymphocyte adhesion was not due to quantitative but a qualitative change induced in LFA-1 molecule upon lymphocyte stimulation. These findings suggest that LFA-1 is normally inert but can be "switched" upon lymphocyte stimulation to participate in lymphocyte-HE cell interaction, and that the LFA-1's ligand specificity can be differentially regulated at the lymphocyte-HE venule interface.

Animals↗
PubMed1991

Infection of human CD4+ rabbit cells with HIV-1: the possibility of the rabbit as a model for HIV-1 infection.

Although human T cell surface glycoprotein CD4 is the cellular receptor for human immunodeficiency virus 1 (HIV-1), the introduction of the human CD4 gene into murine cells does not render them susceptible to HIV-1 infection. Here we have established rabbit transfectant cell lines expressing human CD4 on the cell surface and demonstrated that the CD4+ rabbit transfectants could be readily infected by HIV-1 by co-cultivating with a HIV-1-infected human MOLT-4 T cell line (MOLT-4/HIV). Avid syncytia formation was observed upon co-cultivation and the syncytia abundantly produced HIV-1 mature particles, as revealed by electron microscopy. A significant increase of HIV-1 p24 antigen was also detected in the culture supernatant. The syncytia formation was blocked by pretreating the transfectant with anti-human CD4 or by pretreating the MOLT-4/HIV with anti-HIV-1 serum obtained from an infected individual, indicating that the syncytia formed as a result of the interaction of human CD4 on the rabbit transfectant with the HIV-1 envelope protein expressed on MOLT-4/HIV. In contrast, only a very small proportion of the rabbit transfectants expressed HIV-1-specific antigens upon infection with an HIV-1 stock. This may indicate that, although rabbit cells have partially acquired susceptibility to HIV-1 by transfection of human CD4 gene, rabbit cells may further require such a molecule as might be provided by MOLT-4 to become fully susceptible to HIV-1 infection. The possibility of the rabbit as a model for HIV-1 infection is also discussed.

Animals↗
PubMed1991

Clastic cells of Hassall's corpuscles during acute involution of the thymus induced by cyclophosphamide in guinea pigs.

General and histochemical observations of the thymus were carried out in guinea pigs after injection of cyclophosphamide (280 mg/kg). Acute involution of the thymus induced by cyclophosphamide was accompanied by marked enlargement of Hassall's corpuscles in the first week after injection. However, the markedly enlarged Hassall's corpuscles disappeared entirely by the fourth week. Large cells characterized by pale nuclei with one or two prominent nucleoli became aggregated in the enlarged Hassall's corpuscles by the second week. Their cytoplasm frequently was foamy or vesicular in appearance. Histochemical observations revealed strong activities of nonspecific esterase, acid phosphatase and beta-glucuronidase in these cells. Staining for these lysosomal hydrolytic enzymes was evident not only intracellularly but also extracellularly, indicating the dissolution of Hassall's corpuscles by intensive extracellular enzyme release.

Acid Phosphatase↗
PubMed1991

Increased vascular permeability of Brucella abortus bacilli in the thymus of NZB/W F1 mice.

Various amounts of the bacterium, Brucella abortus (BA) were injected intravenously into autoimmune NZB/W F1 mice and non-autoimmune BDF1 mice and then the localization of BA in the thymus was traced using an immunohistochemical method at 30 min and 3 h after injection. The results showed that a greater amount of BA became consistently localized in the thymic parenchyma in a free form or in a phagocytized form in NZB/W F1 mice in comparison with BDF1 mice, indicating a marked increase of vascular permeability in the thymus of NZB/W F1 mice. The extravascular leakage of BA was clearly dose-dependent. The significance of invasion of bacterial antigens from the general circulation into the thymic parenchyma is discussed in relation to autoimmune states.

Animals↗
PubMed1991

Thymic nurse cells (TNC) in spontaneous thymoma BUF/Mna rats as a model to study their roles in T-cell development.

In order to elucidate possible roles of thymic nurse cells (TNC) we isolated them as lympho-epithelial cell complexes from spontaneous thymomas of BUF/Mna rats and characterized them using immuno- and enzyme-histochemical techniques. A remarkable increase in the number of TNC was seen at 8 months of age, immediately before or in accordance with the onset of thymomas. No structural abnormality in the TNC was detected by light-microscopy compared with those from normal control thymi. Phenotypically, the TNC per se were positive for major histocompatibility complex (MHC) class I, class II, cytokeratin and thymulin, but lacked macrophage markers, indicating their epithelial origin. They also expressed some of the markers for non-epithelial components, such as Thy-1, S100 and peanut agglutinin (PNA). The majority of intra-TNC cells were MHC class 1+, Thy-1+, CD5+, CD4+ CD8+ (double positive) and PNA+, but with some heterogeneity in their phenotype. The intra-TNC cells from thymomas revealed higher proliferation indices than those from control thymi, as assessed by 5-bromo-2'-deoxyuridine (BrdU)-uptake. It was also demonstrated for the first time that, not only in thymoma rats but also in normal control rats, about 15-30% of TNC enclosed macrophage populations within them. These results may suggest that the TNC in BUF/Mna thymomas represent typical TNC populations, but they are hyperactive particularly in their number and nursing capacity, resulting in the unusual increment of thymocytes in the thymomas. This animal model lends itself greatly to studies on the regulatory roles of TNC in T-cell development.

Aging↗