Search PubMed⌕ Search

Biomedical subjects

M Kotani

Publications and source records attributed to M Kotani.

At least 91 records · Page 5Linked to original sources
PubMed1990

Localization in the rat spleen of carbon-laden macrophages introduced into the splenic artery: a subpopulation of macrophages entering the white pulp.

Heavily carbon-laden (HC) macrophages, largely derived from the red pulp of the donor spleen, were injected into the splenic artery of recipient rats. Immediately after injection, HC macrophages were found only in the marginal sinus and in the splenic cords. With time after injection, they appeared successively at the periphery of the white pulp, in the deeper white pulp, and finally in and near the germinal centers, suggesting migration of HC macrophages from the marginal sinus towards the germinal centers. The number of HC macrophages in and near the germinal centers reached a peak at 12 h. Most of the HC macrophages in the white pulp were spherical or ovoid in shape with a diameter of 7-11 microns in sections, having an eccentric round or oval nucleus often with a distinct nucleolus and a cap-like or horseshoe-like cytoplasm filled with carbon. When immunostained with monoclonal antibodies against rat macrophage subpopulations, more than 90% of HC macrophages in the white pulp were found to be ED1+2-3-. A population of the same type of macrophages, both in morphology and phenotype, were found in the red pulp of the donor spleen. They were different from the major residents, red pulp scavenger macrophages, which were ED1+2+3- and larger in size and irregular in shape. These results suggest the presence of a distinct subpopulation of macrophages which actively migrate into the splenic white pulp including the germinal centers. A discharge of transferred macrophages from the red pulp to the general circulation is also suggested.

Alkaline Phosphatase↗
PubMed1990

The liver lymphatics as a migratory pathway of macrophages from the sinusoids to the celiac lymph nodes in the rat.

A migratory pathway of macrophages as well as lymphatic communications from the liver to the celiac lymph nodes were studied both macroscopically and histologically. The injection of gelatinized carbon into the porta hepatis revealed a new pathway of the liver lymphatics running independently of the portal vein in addition to the ordinary periportal lymphatics. By obstruction of the efferent lymph flow of the celiac nodes and immunostaining with a monoclonal antibody to lymphatics, perilobular lymphatic vessels in the portal tract was readily demonstrated. It was suggested that heavily carbon-laden (HC) macrophages had migrated from the sinusoid into the interlobular connective tissue by 6 h after an intravenous injection of carbon, and then entered the lymphatic vessels of the portal tract. By 9 h to 12 h after carbon injection, HC macrophages started to migrate into the celiac nodes via the two lymphatic pathways. From the marginal sinus in the celiac nodes, they moved into the interfollicular area of the superficial cortex, then accumulated in the paracortex by 12 h to 24 h. They finally ended up in the corticomedullary junction. Migrating HC macrophages showed morphological homogeneity. The liver lymphatic pathway in the rat and a significance for the translocation and function of migrating macrophages were discussed.

Animals↗
PubMed1990

A new approach for identification of rat lymphatic capillaries using a monoclonal antibody.

In order to discriminate rat lymphatics from blood vessels on tissue cryosections by immunohistochemistry, a mouse monoclonal antibody (B27) was produced by immunization of mice with a homogenate of rat thoracic duct. B27 strongly recognized endothelial cells of almost all rat lymphatics, such as lacteals, lymphatic capillaries in the diaphragm at sites of absorption from the peritoneal cavity, collecting lymphatics and the thoracic duct. Besides the lymphatics, B27 reacted with the endothelium of some types of blood vessel, the mesothelium of the peritoneal cavity and substances between smooth muscle fibers. A new double immunostaining technique was then developed to distinguish the lymphatic capillaries, having no or only scanty basement membranes more clearly from the blood vessels. Cryosections were stained first with an anti-type IV collagen antibody for basement membranes, secondly with B27 for the endothelium, and then examined by either light microscopy or fluorescence microscopy. With this technique, the lymphatic capillaries were easily distinguished from other vessels by their positive reaction with B27 alone. B27 appears to be very useful for the simple and reliable identification of rat lymphatics, particularly lymphatic capillaries, in various tissues when applied for double immunostaining.

Animals↗
PubMed1990

A novel monoclonal antibody, Mar 1, directed specifically against mononuclear phagocyte system cells in rats.

Three different monoclonal antibodies (mAb), designated Mar 1, Mar 2, and Mar 3, recognizing three distinct novel antigen molecules expressed preferentially in rat macrophages, were produced by the hybridoma technique. Binding of these mAb to isolated cells or fixed cells was detected by radioactive binding assay, immunohistochemical technique and flow cytometry. Mar 1 binds specifically to the cells constituting the mononuclear phagocyte system (MPS), but not to granulocytes nor endocytosis-positive cells from non-lymphoid tissues. Mar 2 and Mar 3 recognize both the former and the latter. The isotypes of Mar 1, Mar 2 and Mar 3 were defined as IgG1, IgG1 and IgG2b, respectively. These mAb were species specific, allo-non-specific and not cytotoxic for rat peritoneal macrophages. Immunoelectron microscopic observation demonstrated that Mar 1-3 antigens are located on both surface membrane and cytoplasmic membrane structures of peritoneal macrophages, particularly on the limiting membrane of phagocytic small vesicles and large phagosomes. Immunoprecipitation experiments demonstrated that the apparent molecular weights (MW) of the reactive antigens of Mar 1, Mar 2 and Mar 3 are 95,000, 100,000 and 55,000 and 27,000, respectively. These findings indicate that all of Mar 1-3 mAb have considerable value in the identification of rat phagocytes and that, of the three kinds of antigens detected with Mar 1-3, Mar 1 antigen is a specific marker for identification of the cells constituting the MPS and may offer the means to assess the functional capability and differentiation process of the macrophage populations.

Animals↗
PubMed1990

Characterization of intrathymic and extrathymic T cell development in spontaneous thymoma Buffalo/Mna rats.

The developmental status of T cell lineages at prethymic, intrathymic and postthymic stages in spontaneous thymoma Buffalo/Mna (BUF/Mna) rats was characterized on the basis of surface phenotypes and some immune responses. The proportion of bone marrow cell populations was shown to be normal in thymoma rats by immunofluorescence flow cytometry (FACS). In spite of a cortex-predominant appearance of thymomas, the proportion of thymocyte populations was phenotypically normal as assessed by FACS. Double immunohistochemical stainings revealed that a substantial number of single-possible (CD4+CD8- or CD4-CD8+) thymocytes existed not only in the narrowed medullary areas but also in the enlarged cortical areas of the thymomas. In lymph nodes, the proportion of T cells increased with age, reaching 88% after 20 months of age. This increase was due mainly to an increase in the CD8+ population but not the CD4+ population, resulting in low CD4/CD8 ratios. An abnormal increase of Thy1+ immature T cells was also observed in the lymph nodes. However, these phenotypic changes in the T cell lineages in the thymoma rats were not so influential as to alter their immunological reactivities, such as the primary antibody response to a T-dependent antigen, the graft-versus-host reaction and the mixed lymphocyte reaction to allo-antigens. These results suggest the possible presence of some altered differentiation pathways for intrathymic and postthymic T cell development in BUF/Mna rats.

Animals↗
PubMed1990

IL-2 receptors on rabbit T-cell lines and their transfectants expressing the human IL-2 receptor alpha chain.

Low-affinity (dissociation constant: Kd = 7 nM) and high-affinity (Kd = 27 pM) interleukin-2 receptors (IL-2R) were detected on rabbit T-cell lines by IL-2 binding studies. Chemical cross-linking studies using 125I-labelled IL-2 showed that rabbit low-affinity IL-2R was singly expressed alpha-chain (MW 55,000) and that high-affinity IL-2R was composed of at least alpha- and beta- (MW 75,000) chains, similar to the human and murine counterparts. The existence of an additional chain (MW 25,000) was suggested in the rabbit IL-2R. Rabbit T-cell transfectant lines were established by human IL-2R alpha-chain (IL-2R alpha) cDNA transfection. These transfectant lines possessed not only extremely large numbers of human IL-2R alpha (over 10 times more than endogenous rabbit alpha-chain) but also twice as many high-affinity sites as their parental lines. The number of high-affinity sites on the transfectants significantly decreased when human alpha-chains were blocked, indicating that these transfectants expressed high-affinity receptor consisting of the exogenous human alpha-chain and rabbit beta-chain. This was confirmed by cross-linking experiments. The observation that expression of extremely large numbers of exogenous alpha-chains lead to an increase of the total number of high-affinity sites in the apparent absence of an increase of beta-chain expression raises the possibility that not only the beta-chain but also the alpha-chain may play an important role in regulating the number of high-affinity receptors.

Animals↗
PubMed1990

Analysis of B-cell abnormalities in autoimmune mice by in vitro culture system using two types of bone marrow stromal cell clone.

B-cell abnormalities in 4-week-old autoimmune NZB and NZB/WF1 mice were studied with an in vitro culture system using two types of stromal cell clone, ST2 and PA6. ST2 supports B lymphopoiesis, and PA6 maintains B progenitors which do not express a B-lineage antigen (B220), but does not allow their further differentiation into B220+ B-lineage cells. B progenitors developed into B-lineage cells when transferred to the ST2 layer. B-lineage cells generated in this way showed hyperproliferation autoimmune mice, and the frequencies of B-lineage cells in the bone marrow of these mice were high. In contrast, the frequencies of B progenitors in the bone marrow were low. These results suggest that abnormal B-cell formation in autoimmune bone marrow appears at a very early stage of B-cell differentiation, and that B-lineage cells are hyperactive on the ST2 layer in the absence of microenvironmental elements from autoimmune bone marrow. This study indicates that autoimmune B-cell abnormalities can be reproduced in vitro, giving new data at the level of committed B progenitors, suggesting that this culture system will be a useful tool for investigating haemopoietic stem-cell abnormalities in autoimmune mice.

Animals↗
PubMed1989

Splenic outer periarterial lymphoid sheath (PALS): an immunoproliferative microenvironment constituted by antigen-laden marginal metallophils and ED2-positive macrophages in the rat.

In an attempt to reveal the role of antigen-laden marginal metallophil (MM) and other macrophages in the intrasplenic immune response of a specific B-cell lineage to a thymus-independent type-2 antigen (Ficoll conjugated with fluorescein isothiocyanate), simultaneous immunohistological observations of the involved cells were performed in the rat. By newly established methods of double or triple immunostainings, time-kinetics of the following parameters were studied and compared: (1) the antigen, (2) the specific antibody-forming cells (AFC) directed to the fluorescein-isothiocyanate determinant, (3) proliferating cells labeled with 5-bromo-2'-deoxyuridine (BrdU), and (4) macrophage subpopulations recognized by monoclonal antibodies (ED2 and ED3). The antigen localized stably not only in the marginal-zone macrophages but also in the MM except around the follicular area. The increase of BrdU-positive cells was observed from day 2 up to day 4 after antigen injection mostly in the periphery of the periarterial lymphoid sheath (outer PALS), which indicated antigen-induced proliferation. As a novel finding, the majority of AFC, both BrdU-positive and -negative, were either closely associated with the antigen-laden MM, or forming cell clusters with ED2-positive macrophages in the outer PALS. In contrast, there were very few AFC in juxtaposition to antigen-free MM in the follicular area or the antigen-laden marginal zone macrophages. The results led to the proposal of a hypothesis that the antigen-laden MM together with ED2-positive macrophages constitute an immunoproliferative microenvironment for the plasmacellular reaction by accumulating the antigen-specific B-cell lineage and promoting these cells to differentiate into the AFC and to proliferate in the outer PALS.

Animals↗
PubMed1989

Growth-promoting effect of oestriol in a lymphoma lacking oestrogen receptors.

Various doses (1 microgram to 10 mg) of oestriol (E3) were intraperitoneally injected into mice immediately after subcutaneous inoculation of an oestrogen receptor-negative lymphoma cell line (KE-5) established from a spontaneously developed AKR thymic lymphoma. The growth of KE-5 cells was markedly promoted by E3 at the early stage of tumour growth. At this stage, 1 microgram E3 enhanced tumour growth significantly and the maximum effect was obtained with 1 mg E3. Normal female mice showed a higher incidence and shorter latency than males. However, once tumours became palpable, the tumour growth rate appeared to be unaffected. Histological observations using Alcian blue and colloidal iron revealed a marked increase of hyaluronic acid in the subcutaneous connective tissue of the tumour-injection site within 3-5 days after intraperitoneal administration of 1 mg E3. Biochemical analyses showed a rapid and marked increase in skin hyaluronic acid content to over 3 times the control levels (0.25 +/- 0.10 mg g-1 skin) within 3 days of E3 administration. Subcutaneous inoculation of KE-5 cells together with hyaluronic acid (0.2 mg) resulted in markedly enhanced tumour growth, particularly at the early stage. These results suggest that an increase in stromal hyaluronic acid content is the most likely mechanism responsible for the promoting effect of E3 on KE-5 cells.

Animals↗
PubMed1989

Different responses of albumin-containing and alpha-fetoprotein-containing cells to estriol in the adult mouse liver.

A single intraperitoneal injection of 10 mg estriol (E3) rapidly induced a transient decrease in the serum albumin (ALB) level in 3 to 5 days in adult mice. At a dose of 5 mg, E3 showed a remarkable threshold effect on the decline of serum ALB. By immunohistochemistry, two types of ALB-positive cells were found in the liver. Type 1 cells were stained intensely and almost homogeneously throughout all or nearly all their entire cytoplasm, and type 2 cells showed only granular or vesicular cytoplasmic deposits. After administration of 10 mg E3, the type 1 cells diminished rapidly and markedly in direct proportion to the fall in serum ALB from the centro- and mediolobular zones, where they had been normally localized either singly or in small groups. Simultaneously, the granular or vesicular deposits that had been normally stained very weakly in the type 2 cells in the centro- and mediolobular zones became intensely stained along with cells in the perilobular zone. Alpha-fetoprotein (AFP)-containing cells in the liver appeared in maximal numbers at 5 to 7 days after E3 administration. These serological and cytological changes after E3 administration are here discussed on the basis of a possible inverse relationship between ALB and AFP gene expression.

Albumins↗
PubMed1989

Influence of food intake on cold-induced vasodilatation of finger.

When the finger is immersed in ice water, a sharp fall of the skin temperature is followed by its gradual rise due to the cold-induced vasodilatation (CIVD). The present study was attempted to examine whether the CIVD is affected by a small increase in internal heat load due to dietary thermogenesis. A 10-min immersion of the left middle finger in ice water was performed at room temperature of 25-26 degrees C on 12 female subjects 60 min before, and 30 and 90 min after ingestion of a meal containing 700 kcal. Skin temperature of the finger and O2 consumption were continuously measured before, during, and after the immersion. A CIVD index was measured using the data of the rising phase of skin temperature during the immersion. The CIVD index, a newly developed parameter in the present study, could reflect both the rapidity and the magnitude of CIVD response during the immersion. Compared with pre-prandial values, the O2 consumption and the CIVD index significantly increased by 15 and 69%, respectively, at 30 min and by 15 and 50% at 90 min of the post-prandial period. Esophageal temperature was studied on another 5 subjects (1 male and 4 females) and it rose by 0.27 degrees C during the 90-min post-prandial period. The results, in support of the involvement of the central nervous system control in CIVD, suggest that the central process is so sensitive as to operate in a 15% increase in heat load into the body.

Adult↗
PubMed1988

Increased vascular permeability in the thymus of the autoimmune New Zealand mouse.

The thymus glands of non-autoimmune BDF1 and C3H mice and autoimmune NZB/WF1 mice were studied histologically at intervals ranging from one hour to 60 days after systemic administration of carbon. In NZB/WF1 mice over 9 weeks of age, many circulating carbon-laden macrophages were seen to have penetrated the walls of blood vessels, and to have then entered the thymic parenchyma. Carbon was also taken up by many perivascular macrophages stretched out along blood vessels and by many resident tissue macrophages scattered throughout the thymic parenchyma. In contrast, no carbon was seen at any time in the extravascular tissues of the thymus in BDF1 and C3H mice of comparable age. These results indicate a great increase in the permeability of blood vessels in the thymus of NZB/WF1 mice. This increase in carbon permeability occurs both in the cortex and the medulla, particularly at the corticomedullary junction. There is little increase in the permeability to carbon in NZB/WF1 mice at the age of 4 weeks, suggesting that the increase in vascular permeability begins between the ages of 4 and 9 weeks. The possible role of this greatly increased blood vessel permeability in the thymus on the aetiology and pathogenesis of autoimmune disease is discussed.

Animals↗