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Biomedical subjects

S Arai

Publications and source records attributed to S Arai.

At least 109 records · Page 6Linked to original sources
PubMed1999

Induction of cyclooxygenase-2 messenger RNA after transient and permanent middle cerebral artery occlusion in rats: comparison with c-fos messenger RNA by using in situ hybridization.

OBJECT: Recently, two different cyclooxygenase (COX) genes, COX-1 and -2, were identified. In this study, topographic and chronological profiles of COX-2 messenger (m)RNA and c-fos mRNA expression were investigated using in situ hybridization after focal cerebral ischemia. METHODS: Rats undergoing permanent ischemia were decapitated at 30 and 90 minutes and at 2, 4, 8, and 24 hours after middle cerebral artery (MCA) occlusion, and rats undergoing transient ischemia were decapitated at 4, 8, and 24 hours after MCA occlusion that lasted for either 30 or 90 minutes. After brief transient MCA occlusion, c-fos mRNA was induced in the whole MCA territory, adjacent cortex (cingulate cortex), and distant brain regions such as the hippocampus and substantia nigra. In contrast, COX-2 mRNA was not induced in the ischemic core (lateral striatum) but only in the penumbral area (MCA cortex). Long transient and permanent MCA occlusion did not induce c-fos and COX-2 mRNAs in the ischemic core but strongly induced both mRNAs in the penumbral area (medial striatum and periphery of MCA cortex) and adjacent cortex (cingulate cortex). In brain regions distant from the ischemic territory, although c-fos mRNA was induced in the thalamus, substantia nigra, and hippocampus after extended transient and permanent occlusion, COX-2 mRNA was only induced in the bilateral hippocampi. The induction of COX-2 mRNA persisted in all locations even at 24 hours after MCA occlusion. CONCLUSIONS: The distribution of COX-2 mRNA induction was apparently different from that of c-fos mRNA after MCA occlusion. These results pertaining to COX-2 mRNA agree well with the previous observations of changes in prostaglandin metabolism induced by focal cerebral ischemia. However, whether this induction of the COX-2 gene contributes to the histopathological outcome of cerebral ischemia remains to be elucidated.

Animals↗
PubMed1999

Dynamic morphology of the cardiac ventricle.

OBJECTIVE: To describe the outline of the ventricular wall on the basis of physiologic data. STUDY DESIGN: Applying the finite deformation theory, we introduced equilibrium equations to obtain the stress-strain relationship of canine myocardial fibers. This was then applied to drawing the shape of the ventricular wall by the finite element method. RESULTS: The outlines of the ventricle wall corresponded to those seen on an echocardiogram. CONCLUSION: Our method is applicable to the present purpose.

Animals↗
PubMed1999

[Cutaneous manifestations with ulcerative colitis].

Here, we reviewed the skin diseases with ulcerative colitis. The cutaneous manifestations were divided 7 groups; 1) pyoderma gangrenosum (PG), 2) erythema nodosum (EN), 3) acneiform eruption, 4) aphtha, 5) bullous diseases (Bullous pemphigoid, Linear IgA bullous dermatosis), 6) urticarial vasculitis, 7) pyostomatitis vegetans. Most of these skin manifestations were occurred after the onset of UC. These were commonly parallel with the clinical course of UC. The pathomechanisms of the cutaneous alterations have not been fully understood. However, these signs seen in the UC patients were important for the evaluations of disease activity of UC.

Acneiform Eruptions↗
PubMed1998

Molecular cloning and taste bud-specific expression of a novel cyclic nucleotide-gated channel.

Cyclic nucleotide-gated (CNG) channels serve as downstream targets of signaling pathways in vertebrate photoreceptor cells and olfactory sensory neurons. For taste signaling as well, a great deal of information is available predicting the presence of a CNG channel, but no report has been presented on its molecular entity. Here we report on molecular cloning and functional expression of a taste bud-specific CNG channel tentatively named CNGgust. Reverse transcriptase polymerase chain reaction (RT-PCR) primers were synthesized according to some amino acid sequences generally conserved in many CNG channels. RT-PCR was conducted using rat circumvallate papillary mRNA-derived cDNA as a template to obtain positive clones. A corresponding genomic DNA clone was then obtained by screening from a genomic DNA library. Dissecting the entire structure of this gene, we found that the encoding protein had an amino acid sequence similarity of 80% to each of retina and olfactory CNG channels. It was also found by immunostaining with a specific antibody that this gustatory CNG channel (CNGgust) is localized in the tongue and also expressed specifically on the pore side of each taste bud in the circumvallate papillae. Electrophysiological experiments demonstrated that CNGgust resided in a functional state. All these data suggest that CNGgust may be involved in taste signal transduction in sensory cells.

Amino Acid Sequence↗
PubMed1998

Identification of two alpha-subunit species of GTP-binding proteins, Galpha15 and Galphaq, expressed in rat taste buds.

We cloned cDNAs for two G protein alpha-subunits belonging to the Galphaq family, each capable of activating PLCbeta, from rat tongue. One is a Galphaq in the narrow sense, and the other, termed rat Galpha15, is a rat counterpart of mouse Galpha15, sharing an amino acid sequence similarity of 94%. RT-PCR and Northern blot analysis demonstrated that rat Galpha15 and Galphaq were distinctly expressed in tongue epithelia containing taste buds. Immunostaining also showed that rat Galpha15, together with the Galphaq, was localized mainly in taste buds. These studies suggest the possibility that these two Galpha proteins function for taste signal transduction in sensory cells.

Amino Acid Sequence↗
PubMed1998

An anergic cytotoxic T lymphocyte clone exhibits granule exocytosis-mediated cytotoxicity.

T cell receptor (TCR) occupancy in the absence of a costimulatory signal transforms T helper (Th) cells or cytotoxic T lymphocytes (CTL) into a state of anergy. The anergic T cells are unable to produce cytokines; nevertheless, they maintain their killing activity. We investigated the mechanisms through which anergic CTL causes lysis of target cells. Treatment of a CTL clone with phorbol myristate acetate and calcium ionophore A23187 (P/A) transformed these cells to anergic cells. While the anergic CTL clones failed to secrete TNF-alpha in the culture supernatant, they were still able to kill antigen-specific target cells via a granule exocytosis-mediated pathway. This was evident by the synthesis of perforin mRNA and release of N-alpha-benzyloxycarbonyl-L-lysine thiobenzyl ester esterase by these cells. The anergic CTL clone also showed a low degree of Fas-mediated lysis of normal target cells. In addition, we generated anergic bulk CTL by treatment with P/A and observed that the anergic bulk CTL failed to produce TNF upon antigen stimulation, but retained target killing activity via a granule exocytosis mechanism. Our results suggest that the killing mechanisms of anergic CTL are mediated to a large extent by a granule exocytosis-mediated pathway.

Animals↗
PubMed1998

Identification and characterization of a novel SH3-domain binding protein, Sab, which preferentially associates with Bruton's tyrosine kinase (BtK).

Protein interaction cloning method was used to identify a novel molecule, Sab, which binds to the SH3 domain of Bruton's tyrosine kinase (Btk), the deficient cytoplasmic tyrosine kinase in human X-linked agammaglobulinemia and murine X-linked immunodeficiency. Immunoprecipitation using the anti-Sab antibody identified the protein product of the gene as a 70 kDa molecule. While Sab does not have a proline-rich sequence, it was shown to bind to Btk through the commonly conserved structure among SH3 domains. Remarkably, Sab exhibited a high preference for binding to Btk rather than to other cytoplasmic tyrosine kinases, which suggests a unique role of Sab in the Btk signal transduction pathway.

Adaptor Proteins, Signal Transducing↗
PubMed1998

Deficient expression of Bruton's tyrosine kinase in monocytes from X-linked agammaglobulinemia as evaluated by a flow cytometric analysis and its clinical application to carrier detection.

The B-cell defect in X-linked agammaglobulinemia (XLA) is caused by mutations in the gene for Bruton's tyrosine kinase (BTK). Using the anti-BTK monoclonal antibody (48-2H), a flow cytometric analysis of intracytoplasmic BTK protein expressed in monocytes was successfully performed. To examine the possible identification of XLA patients and female carriers by this assay, we studied 41 unrelated XLA families with (35) or without (6) known BTK mutations. A flow cytometric assay showed deficient expression of the BTK protein in 40 of 41 patients, complete BTK deficiency in 35, and partial BTK deficiency in 5. One patient exhibited a normal level of BTK expression. All 6 patients with partial BTK deficiency or normal BTK expression had missense BTK mutations. The cellular mosaicism of BTK expression in monocytes from obligate carriers was clearly shown in 35 of 41 families. The results suggested that most BTK mutations in XLA might result in deficient expression of the BTK protein. We conclude that deficient expression of BTK protein can be evaluated by a flow cytometric assay, and the clinical usefulness and limitations in diagnosis of XLA patients and carriers are discussed.

Adolescent↗
PubMed1998

Ultrastructure of human scalp hair shafts as revealed by freeze-substitution fixation.

Human scalp hair is important as a diagnostic clue to many diseases, in medical jurisprudential investigations, and also as a subject of cosmetic treatments. While many ultrastructural studies of the human hair root including the hair follicle have been reported, few studies have been done on the human hair shaft. We report here the ultrastructure of human scalp hair shafts prepared by a rapid-freezing technique followed by freeze-substitution fixation that allows the observation of fine cell structures. Healthy scalp hair shafts from Japanese females 12-13 years of age were rapid-frozen and then freeze-substituted in OsO4-acetone. In addition, this technique was applied to the study of some changes of the hair shafts (i.e., hair damaged by thioglycolic acid cold permanent waving and white hair). By this method, the hair shaft was rapid-frozen throughout without appreciable ice damage although the hair shaft was nearly 100 microm in diameter. The rapid-freezing technique resulted in excellent preservation of the ultrastructure of the hair shafts: lamellar structures in the cuticle and fine fibrous ultrastructures in the cortex were observed without chemical treatments. Thioglycolic acid treatment affected the ultrastructure of both the cuticle and the cortex. Except for the absence of melanin granules, no significant differences in the ultrastructure were observed between white hair and black hair. The rapid-freezing technique followed by freeze-substitution fixation appears to be the most reliable approach for the morphological evaluation of fully keratinized cells and tissues.

Adolescent↗
PubMed1998

Selective bowel decontamination of recipients for prevention against liver injury following orthotopic liver transplantation: evaluation with rat models.

Gut-derived substances can activate Kupffer cells to provoke hepatic necrosis after partial hepatectomy in rats. A similar situation may occur during orthotopic liver transplantation (OLT), as congestion in the intestinal wall, caused by portal vein occlusion, is inevitable during the operation. The contribution of such substances to liver injury following OLT was investigated in rats. Oral administration of polymyxin B sulfate for 7 days significantly altered intestinal bacterial flora in rats; Enterobacteriaceae diminished and anaerobes such as Bifidobacterium , Lactobacillus, Bacteroides, and Eubacterium increased in number, compared with the control rats. Also, this treatment significantly reduced endotoxin concentration in the portal blood 30 minutes after blood reflow following portal vein occlusion. When OLT was performed in rats using the liver preserved in cold University of Wisconsin solution for 18 hours, tissue factor activity in Kupffer cells (KC) isolated from the transplanted liver 1 hour after the operation was significantly higher than in that of normal rats. This increase was significantly reduced by pretreatment of the recipients with polymyxin B sulfate. In these recipients, serum alanine aminotransferase activity, tumor necrosis factor alpha (TNF alpha) concentration, and histological extent of liver necrosis were significantly attenuated at 24 hours after the operation compared with those of control rats. We conclude that the substances derived from bacilli sensitive to polymyxin B sulfate in the gut may be a contributing factor to liver injury following OLT in rats; we feel that this probably occurs by entering of the substances into the portal blood during the ahepatic phase of the operation to activate KC. Selective bowel decontamination of recipients with polymyxin B sulfate would be a candidate for protection against early graft failure following OLT.

Animals↗
PubMed1998

Intramuscular injection of plasmid DNA expressing mRNA7 coding the nucleocapsid protein of JHMV partially protected mice against acute infection with JHMV.

We constructed a plasmid expressing mRNA7 coding the nucleocapsid (N) protein of JHM strain of mouse hepatitis virus (JHMV) under the control of Rous sarcoma virus LTR, referred to as pRSV-mRNA7. When C57BL/6 mice injected intramuscularly (i.m.) with control plasmid DNA which contained no viral sequence were infected with JHMV, necrotic figures of neural cells and diffuse immersion of lymphatic cells in the pedunculus cerebri were observed. In the hypothalamus, vascular cuffing consisting of lymphatic cells was observed. In contrast, no histological change was observed throughout these areas of the brains in the JHMV-infected mice after injection with pRSV-mRNA7. These results showed that the injection with plasmid DNA expressing mRNA7 of JHMV partially protected mice against acute infection with JHMV in the brain. The plasmid DNA was i.m. injected into mice and the cytolytic activity of spleen cells from the mice was assessed by 51Cr-release assay. The spleen cells from the mice administrated with pRSV-mRNA7 showed a significant level of cytolytic activities against the transfected cells expressing the viral N protein even though the spleen cells were not cocultivated with stimulator cells. When the spleen cells from administrated mice with pRSV-mRNA7 were cocultivated with stimulator cells, higher cytolytic activity was observed against the transfected cells, compared with the activity without stimulation.

Acute Disease↗
PubMed1998

Inhibitory effects of modified oligonucleotides complementary to the leader RNA on the multiplication of mouse hepatitis virus.

Phosphorothioate oligonucleotides (PS-oligo) and PS-oligos with cholesterol conjugates (ChPS-oligo) complementary to the leader RNA of strain JHM of mouse hepatitis virus (JHMV) were more effective inhibitors of viral multiplication than natural oligodeoxynucleotides (PO-oligo) in JHMV-infected DBT cells. PS- and ChPS-oligos were 1,000 times more potent than unmodified PO-oligo. No significant difference was observed in the inhibitory efficiency between PS-oligo and ChPS-oligo. Sequence-dependent inhibition of viral multiplication was shown at low concentrations (0.001-0.1 M) of antisense PS-oligo and ChPS-oligo. Phosphorothioate oligodeoxycytidine, PS-(dC)20, and PS-(dC)20 with cholesterol conjugates, and PS- and ChPS-oligo which have no significant homology to the JHMV sequences, showed inhibitory effects on JHMV multiplication at concentrations higher than 0.5 M. These results showed that PS-oligo and ChPS-oligo were more potent than PO-oligo in the inhibition of JHMV multiplication, and that PS-oligo and ChPS-oligo may inhibit JHMV multiplication by two different mechanisms, that is by sequence-dependent and sequence-independent manners.

5' Untranslated Regions↗
PubMed1998

System B0,(+)-mediated regulation of lysine transport in Caco-2 human intestinal cells.

We investigated whether lysine transport would be subject to adaptive regulation in Caco-2 human intestinal cells. The activity of Lys transport in Caco-2 cells decreased with increasing incubation time with 10 mM Lys. Among the two systems involved in Lys transport, the system b0,+ component was greatly decreased by incubating cells with 10 mM Lys, whereas the system y+ component did not change. These results suggest that system b0,+ mainly contributes to the adaptive regulation of Lys transport in Caco-2 cells.

Amino Acid Transport Systems↗
PubMed1998

Successful chemotherapy in a patient with recurrent carcinoma of the urachus.

Urachal neoplasm generally has a poor prognosis, because of long latency period, extravesical progression and pathological predominant pattern of adenocarcinomas. We report a case of recurrent poorly differentiated carcinoma of urachal remnant, which responded well to combination systemic chemotherapy (methotrexate, vinblastine, doxorubicin and cisplatin: M-VAC). Our case was possibly of transitional cell origin. The patient has been symptom-free even 13 months after the first chemotherapy course.

Antineoplastic Combined Chemotherapy Protocols↗
PubMed1998

Interaction of gangliosides with proteins depending on oligosaccharide chain and protein surface modification.

By using neutron and synchrotron x-ray small-angle scattering techniques, we investigated the process of the complexation of gangliosides with proteins. We treated monosialoganglioside (G(M1)), disialoganglioside (G(D1a)), and a mixture of G(M1)/G(D1a). Proteins used were bovine serum albumins whose surfaces were modified with different sugars (deoxy-D-galactose, deoxy-L-fucose, deoxymaltitol, and deoxycellobiitol), which were used as model glycoproteins in a membrane. We found that the complexation of gangliosides with albumins greatly depends on the combination of ganglioside species and protein surface modification. With a varying protein/ganglioside ratio in a buffer solution at pH 7, the complexation of G(M1) or G(D1a) with albumins modified by monosaccharides appears to be less destructive for ganglioside aggregate structures in forming large complexes; the complexation of G(D1a) with the albumins modified by disaccharides induces the formation of complexes with a dimeric structure; and the complexation of G(M1) with albumins modified by disaccharides, to form small complexes, is very destructive. The present results show a strong dependence of the interaction between ganglioside and protein on the characteristics of the ganglioside and protein surface, which would relate to a physiological function of gangliosides, such as a function regulating the receptor activity of glycoproteins in a cell membrane.

Animals↗
PubMed1998

Babesia canis infection in canine-red blood cell-substituted SCID mice.

We have developed a mouse model for Babesia canis infection using severe combined immunodeficiency (SCID) mice whose circulating red blood cells had been substituted with canine red blood cells. Substitution of red blood cells in SCID mice was achieved by repetitive transfusions of canine red blood cells, together with administration of an antimouse red blood cell monoclonal antibody. Following inoculation of canine-red blood cell-SCID mice with B. canis, parasites proliferated in the canine red blood cells that had been transfused into the SCID mice, resulting in much higher parasitaemia than that observed in dogs. In an attempt to demonstrate the utility of this mouse model, three antiprotozoal drugs, diminazene diaceturate, clindamycin and oxytetracycline, were examined for their efficacy to inhibit the growth of B. canis in canine-red blood cell-SCID mice. The mouse model clearly showed that diminazene diaceturate and oxytetracycline were capable of eliminating B. canis from the canine-red blood cell-SCID mice, whereas clindamycin exhibited only a static effect as parasitaemia relapsed upon cessation of drug administration.

Administration, Cutaneous↗
PubMed1998

Immunohistochemical demonstration of spread of Aujeszky's disease virus to the porcine central nervous system after intestinal inoculation.

Aujeszky's disease virus (ADV) was injected into the duodenal lumen of eight specific pathogen-free pigs aged 5 weeks. The infected pigs did not show any diarrhoea or nervous symptoms, but they developed characteristic necrotizing enteritis and myenteric plexitis, accompanied by follicular necrosis in the Peyer's patches. ADV antigen was detected in the submucosa of the dome area of Peyer's patches, lymphatic follicles, Meissner's and Auerbach's plexuses, solar ganglia and thoracic spinal ganglia. These findings suggest that ADV spreads from the intestinal mucosa to the central nervous system via the autonomic nerves.

Animals↗