Biomedical subjects

M Ohbayashi

Publications and source records attributed to M Ohbayashi.

At least 19 recordsLinked to original sources

PubMed2001

Colocalization of neuropilin-1 and Flk-1 in retinal neovascularization in a mouse model of retinopathy.

PURPOSE: To investigate the mechanisms of the development of retinal neovascularization, the localizations of vascular endothelial (VEGF) receptors Flk-1 and neuropilin (NP)-1 mRNAs were examined. METHODS: The model of retinopathy of prematurity (ROP) was produced by ischemia-induced ocular neovascularization, by exposing postnatal day-7 mice to 75% oxygen for 5 days and then returning them to room air for 5 days. Retinal neovascularization was visualized by injection of fluorescein-dextran. Expression of Flk-1 and NP-1 mRNAs were examined by in situ hybridization with flatmount and serial sections of the retina. The localization of NP-1 was also confirmed by immunohistochemistry. Blood vessel patterns were characterized by immunohistochemical localization of von Willebrand factor (vWF). RESULTS: Flatmount in situ hybridization showed intense expression of NP-1 and Flk-1 mRNAs colocalized in the area of neovascularization. In situ hybridization of serial sections of the retina revealed that expression of Flk-1 and NP-1 was restricted to neovascularized vessels of the retina from ROP mice. CONCLUSIONS: The restricted expression of Flk-1 and NP-1 on neovascularized vessels suggests that these molecules may play important roles in retinal neovascularization. This is the first report of the colocalization of NP-1 and Flk-1 on neovascularized vessels of the retina from ROP mice.

Animals↗

PubMed1999

Expression of chimeric P450 genes encoding flavonoid-3', 5'-hydroxylase in transgenic tobacco and petunia plants(1).

Flavonoid-3',5'-hydroxylase (F3'5'H), a member of the cytochrome P450 family, is the key enzyme in the synthesis of 3', 5'-hydroxylated anthocyanins, which are generally required for blue or purple flowers. A full-length cDNA, TG1, was isolated from prairie gentian by heterologous hybridization with a petunia cDNA, AK14, which encodes F3'5'H. To investigate the in vivo function of TG1 and AK14, they were subcloned into a plant expression vector and expressed under the control of the CaMV35S promoter in transgenic tobacco or petunia, both of which originally lack the enzyme. Transgenic petunia plants had a dramatic change in flower color from pink to magenta with a high content of 3',5'-hydroxylated anthocyanins. In contrast, transgenic tobacco plants had minimal color change with at most 35% 3',5'-hydroxylated anthocyanin content. These results indicate that the products of TG1 and AK14 have F3'5'H activity in planta and that interspecific gene transfer alters anthocyanin pigment synthesis. The difference in apparent F3'5'H activity between tobacco and petunia is discussed.

Amino Acid Sequence↗

PubMed1999

Top-down signal from prefrontal cortex in executive control of memory retrieval.

Knowledge or experience is voluntarily recalled from memory by reactivation of the neural representations in the cerebral association cortex. In inferior temporal cortex, which serves as the storehouse of visual long-term memory, activation of mnemonic engrams through electric stimulation results in imagery recall in humans, and neurons can be dynamically activated by the necessity for memory recall in monkeys. Neuropsychological studies and previous split-brain experiments predicted that prefrontal cortex exerts executive control upon inferior temporal cortex in memory retrieval; however, no neuronal correlate of this process has ever been detected. Here we show evidence of the top-down signal from prefrontal cortex. In the absence of bottom-up visual inputs, single inferior temporal neurons were activated by the top-down signal, which conveyed information on semantic categorization imposed by visual stimulus-stimulus association. Behavioural performance was severely impaired with loss of the top-down signal. Control experiments confirmed that the signal was transmitted not through a subcortical but through a fronto-temporal cortical pathway. Thus, feedback projections from prefrontal cortex to the posterior association cortex appear to serve the executive control of voluntary recall.

Animals↗

PubMed1999

Basic study on gene therapy of human malignant glioma by use of the cationic multilamellar liposome-entrapped human interferon beta gene.

For gene therapy of human malignant glioma, we adopted positively charged multilamellar liposomes entrapping the human interferon beta (hIFN-beta) gene. One week after the transplantation of human malignant glioma U251-SP cells to produce glioma in nude mouse brain, the liposomes entrapping the gene (500 ng of DNA per 25 nmol of lipids per 2 microl) were injected into the same site of the cell transplantation once every second day for a total of five injections; and by this means the tumor completely disappeared. To confirm the antiproliferative effect of hIFN-beta, we performed an in vitro study using a plasmid containing a secretion signal sequence-deleted hIFN-beta gene and one containing the hIFN-beta gene inserted in reverse. In both cases, there was no hIFN-beta release into the medium and no growth inhibition effect. On addition of anti-hIFN-beta antibody to the medium, the growth inhibition effect was abolished. As this cell line expresses IFN-alpha/beta receptor, the hIFN-beta produced in the transfected cells could be released and acted in a paracrine manner. For 120 days the body weight change of normal mice treated by the same procedure as used in the curing experiment was not significant among the groups injected with empty liposomes, plasmid only, and liposomes entrapping the gene. In all of these three groups, death, abnormal behavior, and significant histological changes were not observed.

Animals↗

PubMed1999

Linkage between melanocytic tumor development and early burst of Ret protein expression for tolerance induction in metallothionein-I/ret transgenic mouse lines.

We examined the basis of the all or none difference in inducing melanocytic tumor development among three transgenic mouse lines (304, 192 and 242) to which the same promoter-enhancer (metallothionein-I) and oncogene (ret) were introduced. We initially demonstrated that both skin melanosis and Ret protein expression in skin, thymus and brain first became detectable before or immediately after birth in the mice of the tumor developing lines (304 and 192), whereas they became detectable a few days after birth in the mice of the non-tumor developing line (242) by Western blotting and immunohistochemical analysis. Interestingly, the Ret protein expression in skin developed rapidly after birth as a burst with peak levels on 0.5-1.5 day newborns of lines 304 and 192 and on 7.0-7.5 day-old mice of line 242. The levels of autophosphorylation of Ret kinase in skin were, however, invariable among these three transgenic mouse lines. The mice of line 242, but not those of lines 192 and 304, responded to Ret protein immunization by increased antigen-dependent lymphocyte proliferation and T-cell-mediated tumor growth suppression in vitro. Furthermore, ret-transgenic mice of line 242, but not line 304, rejected the subcutaneously transplanted tumors that had originally developed in a mouse of line 304. These results suggest that whether oncogene product-specific-tolerance is established or not to antitumor immunity may be decided by the dynamics of ret oncogene expression before and after delivery and this is the primary factor determining development or non-development of melanoma.

Animals↗

PubMed1998

The neuronal basis of visual memory and imagery in the primate: a neurophysiological approach.

To understand the biological basis of memory is one of the most exciting frontiers of science. Single unit recording is a powerful method to investigate neuronal correlates of various brain functions such as memory in awake animals. Anatomical, neuropsychological, and neurophysiological evidence indicates that the IT has an important role not only for synthesizing the analyzed visual attribute into a unique configuration, but also for the storehouse of visual memory in humans and primates. We performed single unit recordings in the primate IT, and found neuronal correlates of visual long-term memory: the IT neurons could reflect learned associative relations among stimuli. The findings reviewed here support the hypothesis that the IT is a region of the brain where visual perception meets memory and imagery.

Animals↗

PubMed1997

Kinetics and collagenolytic role of eosinophils in chronic gastric ulcer in the rat.

An association between eosinophils and tissue damage has been observed in numerous disorders. However, few reports have addressed the role of infiltrating eosinophils in gastric ulcer healing. The aim of this study was to investigate the kinetics and role of eosinophils infiltrating experimental chronic gastric ulcers in the rat. We developed a monoclonal antibody against human matrix metalloproteinase 1 (MMP1) purified from conditioned culture medium of human skin fibroblasts. Acetic acid-induced gastric ulcers were resected from rats on days 1, 3, 5, 10, 20, 40, and 180 after the days of induction (day 0). Tissue specimens were immunostained with this antibody and examined with an electron microscope. Few eosinophils were observed in the granulation tissue until day 20. By days 40 and 180, MMP1-positive eosinophils had increased in the granulation tissue of open ulcers. Azan staining revealed dispersed collagen fibers around infiltrating eosinophils. In contrast, scars demonstrated few eosinophils in fibrous tissue on days 40 and 180. Eosinophils which express MMP1 infiltrate granulation tissue at the chronic stage of gastric ulceration. The results suggest that eosinophils may play a role in tissue remodeling and deterioration of ulceration.

Acetic Acid↗

PubMed1997

Monoclonal antibodies against mouse splenic stromal cells.

A panel of rat monoclonal antibodies directed against mouse splenic stromal cells were isolated. These monoclonal antibodies were immunohistochemically divided into four groups which reacted with non-lymphoid cells of the murine spleen; (I) in the white pulp, (II) at the marginal zone, (III) in the red pulp, and (IV) on the endothelium of splenic blood vessels. These monoclonal antibodies were studied immunohistochemically in lymphoid organs by means of light and electron microscopy. Monoclonal antibodies SS-4 (group I) reacted with fibroblastic reticulum cells that were distributed only in the white pulp of the spleen and in the follicular areas of lymph nodes. The SS-4 staining cell, in clustered splenic stromal cells, formed colonies which included a small number of Thy-1 positive lymphocytes. Therefore, we concluded that SS-4 staining stromal cells comprise the lymphoid compartment. In contrast, monoclonal antibodies SS-1, SS-3 and SS-5 (group II) reacted with dendritic shaped cells in the marginal zone of the spleen. Examination of splenic extramedullary hematopoiesis in mice rescued by bone marrow transplantation after lethal irradiation revealed that SS-3 and SS-5 reacted with dendritic shaped stromal cells in clonal nodules of engrafted marrow in the red pulp. SS-3 and SS-5 staining cells could not be observed in physiologic hematopoiesis of non-transplanted mice. It was suggested that SS-3 and SS-5 staining stromal cells are involved in primitive hematopoiesis. Monoclonal antibodies SS-2, SS-6 and SS-7 (group III) mainly reacted with dendritic cells and macrophages in the red pulp. Monoclonal antibodies SS-B and SS-9 (group IV) reacted with endothelial cells of blood vessels and sinuses. These findings of heterogeneity in mouse splenic stromal cells are further evidence that specific micro-environments are composed by specialized stromal cells.

Animals↗

PubMed1997

Portal-hepatic venous shunt through a portal aneurysm complicated by hepatic encephalopathy and pulmonary hypertension.

We report a rare case of portal-hepatic venous shunt through an enormous portal aneurysm complicated by pulmonary hypertension. A 66-year-old woman was admitted to our hospital for hepatic encephalopathy. Chest roentgenography revealed pulmonary hypertension. Computed tomography and ultrasound examination demonstrated a shunt between the portal and hepatic veins through an enormous portal aneurysm. The diagnoses of portal-hepatic venous shunt and pulmonary hypertension were confirmed by hepatic venous catheterization and cardiac catheterization. Pulmonary hypertension might result from the effects of vasoconstrictive agents, which should be metabolized by the liver in normal subjects, passing through the intrahepatic shunt into the lung.

Aged↗

PubMed1997

Structure and function of the hemolymph node in rats.

Hemolymph nodes (HLs) are unique lymph nodes, in that their lymphatic sinuses contain numerous erythrocytes. In this study, we compared the internal structure and immunologic function of HLs with those of ordinary lymph nodes (OLs) and the spleen. Electron microscopy revealed erythrocytes passing through the walls of blood vessels in the intermediate sinus area (IMSA) of a HL between expanded endothelial cell junctions. However, no direct communication was found between lymphatic sinuses and blood vessels. Numerous carbon particles appeared in the IMSA of HLs on 5 days after intravenous carbon particle injection, while OLs lacked particle deposition. Immunohistochemical studies showed that lipopolysaccharide (LPS) reached the IMSA of HLs and extravasated into medullary cords 4 hours after intravenous LPS injection, resulting in the appearance of more IgM-stained lymphocytes in the IMSA of HLs than in that of OLs on day 5. The ability of organs to produce antibodies was determined by counting the number of plaque forming colonies after intravenous injection of sheep red blood cells (SRBC). The HLs antibody-producing ability was between that of OLs and the spleen. These results suggest that HLs possess functionally open blood vessels in the IMSA and their immunologic capability is between that of OLs and the spleen. These findings suggests that HLs are lymphoid organs that have characteristics between those of the OLs and the spleen, both ultrastructurally and functionally.

Animals↗

PubMed1996

Kinetics of monocytoid B lymphocytes in localized inflammatory lesions induced by lipopolysaccharide in mice.

Immunohistochemistry was used to study the kinetics of B lymphocytes (B-lys) in the early stages of the localized inflammatory response induced in SMA mice by the subcutaneous injection of lipopolysaccharide (LPS). At the injection sites, medium-sized B-lys formed early inflammatory lesions with neutrophils and activated macrophages on days 1 and 2. The B-lys were morphologically similar to monocytes, but were not stained with Mac1 antibody. Remarkably the B-lys showed the phenotypes of B220+, IgM+, IgD (slight to negative), Ly-1- and CD23- by double immunohistochemical staining. The B-lys were also positive for alkaline phosphatase. Consequently the B-lys could be identified as monocytoid B-lys or marginal zone B-lys. Plasmacytic B-lys and plasma cells were first observed on days 3 and 4, but no lymphoid follicles were found at the injection sites. In the inguinal lymph nodes, the same B-lys responses were mainly induced in the paracortical lesions (T cell areas) preceding the formation of activated germinal centers (GC). These findings suggested that the B-lys, induced by injections of LPS, matured into plasma cells in the localized inflammatory lesions independent of GC, and that they were different from follicular B-lys.

Animals↗

PubMed1996

A new host record of Camelostrongylus mentulatus (Nematoda; Trichostrongyloidea) from abomasum of a giraffe at a zoo in Japan.

Camelostrongylus mentulatus (Railliet et Henry, 1909) Orloff, 1933 (Nematoda; Trichostrongyloidea) was found from the abomasum of a three-year-old female cape giraffe, Giraffa camelopardalis giraffa, born and died in a zoo park in Yamaguchi prefecture, Japan. This is the new host record from Giraffidae and geographical distribution of C. mentulatus. Present case of C. mentulatus might be infected from other ruminants, e.g., camels, antelopes and goats, kept at a same paddock in the zoo. Risk of imported parasitic diseases by the zoo animals from outside of Japan is discussed.

Abomasum↗

PubMed1996

Cardiogenic shock following recombinant alpha-2b interferon therapy for chronic hepatitis C. A case report.

A 57-year-old woman with chronic hepatitis C was treated with alpha-2b interferon (IFN). Forty-five days after the initiation of IFN therapy, she developed cardiogenic shock. Acute perimyocarditis as a cause of cardiogenic shock was clinically suspected by the findings of complete atrioventricular block, regional wall motion abnormality and pericardial effusion. Since IFN therapy may induce cardiogenic shock in some patients, it is important to carefully monitor patients under treatment with IFN for abnormal cardiac signs.

Acute Disease↗

PubMed1996

Adverse effects of interferon on the cardiovascular system in patients with chronic hepatitis C.

The therapeutic effects of interferon in chronic hepatitis C and many of its adverse effects have been well documented. However, there are only a few reports regarding its adverse effects on the cardiovascular system. The aim of this study was to clarify the clinical features of the adverse effects of interferon on the cardiovascular system in patients with chronic hepatitis C. We monitored 295 patients with chronic active hepatitis C during 312 courses of interferon therapy and for 1 year after the end of treatment for the presence of cardiovascular adverse effects. We found 6 patients with cardiovascular adverse effects during interferon therapy and 4 more patients within 1 year after the end of therapy (10/312, 3.2%). The adverse effects of interferon on the cardiovascular system included arrhythmia (n = 4), ischemic heart disease (n = 4) and myocardial disease (n = 2). None of the clinical factors, including history of cardiovascular disease, were related to these cardiovascular adverse effects. In all instances the patient's condition improved after discontinuation of interferon and adequate therapy. The cardiovascular adverse effects of interferon occurred frequently in patients with chronic hepatitis C, even after the end of therapy and they were unpredictable. Thus, all patients undergoing interferon therapy should be monitored not only during but also after the end of treatment.

Arrhythmias, Cardiac↗

PubMed1996

Sarcoidosis after interferon therapy for chronic active hepatitis C.

Sarcoidosis is characterized by multisystemic granulomatous lesions of unknown etiology. A 62-year-old woman developed sarcoidosis after treatment with alpha-2a interferon (IFN) for 24 weeks (total dose: 522 million units) for chronic hepatitis C. She developed complete atrioventricular block and multiple noncaseating granulomatous lesions in the lung. IFN therapy, which may disturb cellular immune activation in some patients, may have contributed to the onset and progression of sarcoidosis.

Antiviral Agents↗

PubMed1995

Immunohistochemical characteristics of chicken spleen ellipsoids using newly established monoclonal antibodies.

Ellipsoids, the extra-vasculature sites surrounding penicilliary capillaries of the chicken spleen, play critical roles in the immune response and also in the clearance of pathogens or other particles. The meshwork of ellipsoids is formed by fibroblastic reticular cells. To characterize ellipsoidal reticular cells, a series of monoclonal antibodies against the chicken spleen have been developed. Of these antibodies, CSA-1 antibody reacts with fibroblastic reticular cells in ellipsoids and with endothelial cells. The reticular nature of positive cells in ellipsoids is indicated by immuno-electron microscopy, and by double staining with anti-heat-shock protein 47 kDa (hsp47) antibody. The reaction of CSA-1 with reticular cells is limited in ellipsoids; CSA-1 does not react with reticular cells in other lymphoid organs. These findings indicate that ellipsoidal reticular cells share the antigen with endothelial cells. Ontogenic studies reveal that, on embryonic day 18, the development of ellipsoids is completed, penicilliary capillaries become fenestrated, and CSA-1 expression in ellipsoids begins. These findings suggest that CSA-1 is expressed on the cell surface of ellipsoidal reticular cells once they are exposed to blood flow.

Animals↗

PubMed1995

Detection of Helicobacter pylori DNA in gastric juice by the polymerase chain reaction: comparison with findings in bacterial culture and the detection of tissue IgA and serum IgG antibodies against Helicobacter pylori.

The detection of Helicobacter pylori in gastric juice by the polymerase chain reaction (PCR) was undertaken in 124 patients with peptic ulcer or chronic gastritis. PCR products were evaluated by agarose gel electrophoresis and Southern hybridization of H. pylori-specific DNA sequences. Positive and negative results of the PCR analysis in 72 examinations were compared with those from bacterial culture, and with the detection of tissue IgA antibody against H. pylori by enzyme-linked immunosorbent assay ELISA; Serion, Wuerzburg, Germany, and detection of serum IgG antibody against H. pylori by ELISA; Radim Pomezia, Italy. Thirty-four PCR-positive samples evaluated by electrophoresis and hybridization coincided with positive samples in 56% of bacterial cultures, 59% of tissue IgA antibody identifications, and 94% of serum IgG antibody evaluations; 26 PCR-negative samples coincided with negative samples in 96% of bacterial cultures, 81% of tissue IgA antibody evaluations, and 38% of serum IgG assessments. We compared the detection achieved with the H. pylori PCR assay in gastric juice with that in biopsies taken from the antrum and upper corpus in 90 examinations, and found them to be both positive in 34 (38%) and 36 (40%) of specimens, both negative in 37 (41%) and 30 (33%) specimens, gastric juice-positive but biopsy-negative in 10 (11%) and 12 (13%) specimens, and vice versa in 9 (10%) and 12 (13%) specimens, when detected by electrophoresis and hybridization, respectively, showing equivalent detection rates. In relation to the type of disease, the positive PCR assay results with gastric juice, evaluated by electrophoresis and hybridization, respectively, were: gastric ulcer 34/53 (64%) and 39/53 (74%), duodenal ulcer 23/38 (61%) and 25/38 (66%), and chronic gastritis 20/33 (61%) and 23/33 (70%), showing no significant difference in positive rates between peptic ulcer and chronic gastritis. Of the samples of 16 patients with H. pylori-positive gastric juice by the PCR assay, 7 were negative by PCR assay analyzed by electrophoresis and hybridization after the completion of treatment H. pylori. However, after treatment, 3 were negative on electrophoresis but still had positive results with hybridization, indicating that a minimal number of bacilli may have still remained. Detection of H. pylori in gastric juice has potential advantages for examining H. pylori infection in the entire stomach and for follow up after treatment for the eradication of H. pylori.

Antibodies, Bacterial↗

PubMed1995

Two phenotypically distinct B lymphocytes (IgMhighIgDlow and IgMlowIgDhigh) in chronic gastric ulcer in the rat.

We determined the kinetics and phenotypes of infiltrating B cells in gastric ulcer in the rat induced by gastric injection of acetic acid (day 0). Few B cells were found in the lesion in the early stages of ulceration. On day 40, two kinds of B cells with phenotypes of IgMhighIgDlowOX33 (CD45)+OX19 (CD5)- and IgMlowIgDhighOX33 (CD45)+OX19 (CD5)- were scattered in the granulation tissue of open ulcers, but not in the healed scar tissue. On day 180, those two kinds of B cells formed primary follicles in the granulation tissue of open ulcers, but were absent from the healed scar tissue. The IgMhighIgDlowOX33 (CD45)+OX19 (CD5)- B cell was considered to be identical to the marginal zone B cell of rat spleen. This phenotype of B cell might be associated with inflammatory process in chronic gastric ulcer.

Acetates↗