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Biomedical subjects

S Shibata

Publications and source records attributed to S Shibata.

At least 181 records · Page 10Linked to original sources
PubMed1999

Expression of the Ets-1 proto-oncogene correlates with malignant potential in human astrocytic tumors.

The protein encoded by the Ets-1 proto-oncogene is a transcription factor that regulates expression of matrix proteases. It has been associated with tumor invasion and angiogenesis. Glioma progression is characterized by increased invasiveness and neovascularization, so we hypothesized that expression of Ets-1 proto-oncogene might play a role in the progression of these tumors. Therefore, we examined the expression of Ets-1 protein by immunohistochemical means and in situ hybridization in tissues obtained from 81 primary and 20 recurrent astrocytic tumors. Twenty-eight (65%) of 43 glioblastomas (Grade IV astrocytomas) stained for Ets-1. The percentage of positive cells in glioblastomas varied from 10 to 90%. Of the 16 anaplastic astrocytomas (Grade III), 4 (25%) were moderately positive (<50% of cells) for Ets-1. None of 22 cases of low-grade astrocytomas (Grade II) expressed endogenous Ets-1. The staining score was significantly associated with tumor grade (P < .0001). Normal brain tissues did not express Ets-1 protein, whereas recurrent astrocytoma cases expressed significantly more positivity for Ets-1 than did primary tumors (P = .03). The Ets-1 protein was observed mainly in the nucleus and corresponded to the cytoplasmic Ets-1 mRNA localization by in situ hybridization. Western and Northern blot analyses confirmed overexpression of Ets-1 protein and mRNA in high-grade tumors. We conclude that Ets-1 protein expression correlates with the malignant potential of tumors of astroglial origin.

Adolescent↗
PubMed1999

[A case of multiple early gastric cancer showing complete response to UFT-E after endoscopic mucosal resection].

A 78-year-old male underwent endoscopic mucosal resection for early gastric cancer (type II a) in the anterior wall of antrum. Follow-up endoscopy showed another early gastric cancer (type II c) in the posterior wall of cardia. He refused an operation. UFT-E 300 mg/day has been administered daily since then. After 6 months, a complete tumor response was observed. The patient has been in good health without any sign of relapse for 14 months after achievement of the complete response.

Adenocarcinoma↗
PubMed1998

Immunohistochemical analysis of metallothionein in astrocytic tumors in relation to tumor grade, proliferative potential, and survival.

BACKGROUND: Metallothionein (MT) is the name for a family of predominantly intracellular protein thiol compounds involved in anticancer drug resistance. For certain tumors, MT is related to grade of tumor malignancy and prognosis. The authors evaluated the expression of MT in 114 astrocytic tumors in relation to the proliferative potential of tumors and the survival of patients. METHODS: Paraffin embedded tissue sections were stained with monoclonal anti-metallothionein and MIB-1 Ki-67 antibodies by avidin-biotin complex immunohistochemistry. RESULTS: MT expression was observed in 2 of 6 pilocytic astrocytomas, in 10 of 24 Grade 2 astrocytomas, in 16 of 25 anaplastic astrocytomas, and in 47 of 59 glioblastomas. In addition to the tumor cells, microvascular endothelial proliferation and smooth muscle of tumor vessel walls were frequently MT positive. The glioblastomas had a significantly higher percentage of MT positive cells compared with low grade (P < 0.0001) and anaplastic (P < 0.04) astrocytomas. MT expression in astrocytomas had no correlation with tumor recurrence. The mean Ki-67 labeling index (LI) was significantly higher in the high grade (3-4) compared with the low grade (1-2) astrocytomas. MT positive astrocytic tumors had statistically significantly higher mean Ki-67 LI compared with MT negative tumors, irrespective of histologic grade. Although the levels of MT and Ki-67 LI varied in individual tumors, the mean Ki-67 LI increased in parallel to the increasing MT staining grade, and this difference attained statistical significance only for glioblastoma. MT positive anaplastic astrocytoma and glioblastoma patients did not survive as long as the MT negative patients, although this difference attained statistical significance only for anaplastic astrocytoma. CONCLUSIONS: The current study suggests that MT might play a significant role in the growth of astrocytic tumors, with an acquired enhanced ability to produce MT as the malignant potential of a tumor increases.

Adolescent↗
PubMed1998

NMDA induced glutamate release from the suprachiasmatic nucleus: an in vitro study in the rat.

The suprachiasmatic nucleus (SCN) has been identified as a pacemaker for mammalian circadian rhythms. Excitatory amino acid receptors, especially N-methyl-D-aspartate (NMDA) receptors, have been considered to play an important role in the transmission of light information from the retina to the circadian clocks in the SCN. In the present study, we showed that application of NMDA at circadian time (CT) 12-15 induced significant glutamate release from the SCN region in vitro. The NMDA-induced glutamate release was blocked by co-application of the NMDA receptor antagonist MK-801, but not by that of tetrodotoxin. These results suggested that glutamate stimulated its own release by activating NMDA receptors. This NMDA-induced glutamate release through NMDA receptor-mediated mechanisms might be involved in NMDA-induced potent phase shifts.

Animals↗
PubMed1998

Molecular cloning and pharmacological characterization of an atypical gerbil angiotensin II type-1 receptor and its mRNA expression in brain and peripheral tissues.

In the gerbil brain, most of the [125I]Sarcosine1-Angiotensin II binding sites are atypical, not sensitive to displacement with selective Angiotensin II AT1 and AT2 receptor ligands. A similar atypical binding profile exists in the gerbil kidney, where binding is highly expressed. We isolated a 2197 base pair clone from a gerbil kidney cDNA library which encodes a 359 amino acid protein with higher than 90% homology to other mammalian angiotensin II AT1 receptors. When expressed in COS-7 cells, stimulation by Angiotensin II of both the cloned gerbil receptor or the human AT1 receptor enhanced IP3 production to a similar degree. In COS-7 cells, the gerbil receptor also had a ligand affinity profile similar to that of the human AT1 receptor, but showed greatly reduced affinity for losartan (IC50=3480+/-174 nM). In the gerbil brain, in situ hybridization revealed receptor mRNA in circumventricular organs, selective hypothalamic, midbrain and brain stem areas, and in the hippocampus, where high mRNA expression was detected in the stratum pyramidale of the CA1 and CA2 subfields, and in the stratum granulosum of the dentate gyrus. The expression pattern of receptor mRNA corresponded well with that of atypical [125I]Sar1-Ang II binding. In situ hybridization and Southern blot experiments using riboprobes against the open reading frame and the 3'-untranslated region of the cloned gerbil Ang II receptor cDNA suggest that gerbils have, like other rodents, two AT1 receptor subtypes. The receptor mRNA distribution of the cloned gerbil Ang II receptor corresponds to the distribution of AT1A receptors described in other rodent species.

Adrenal Cortex↗
PubMed1998

Human parvovirus B19 as a causative agent for rheumatoid arthritis.

Human parvovirus B19 (B19) DNA was detected in the synovial tissues in 30 of 39 patients with rheumatoid arthritis (RA), and infrequently in those with osteoarthritis and traumatic joints. On the other hand, the expression of the B19 antigen VP-1 was specific (27/27) in RA synovium with active synovial lesions, but not in osteoarthritis and controls. The target cells of B19 were macrophages, follicular dendritic cells, T cells, and B cells, but not synovial lining cells in the synovium. B19-negative bone marrow cells, tonsil cells, and macrophage cell line U-937 cells became positive for the expression of VP-1, and more productive for interleukin 6 and tumor necrosis factor alpha when cocultured with RA synovial cells. The expression of VP-1 and the production of interleukin 6 and tumor necrosis factor alpha was significantly inhibited by the addition of neutralizing antibody for B19, suggesting that B19 detected in RA synovial cells is infective. B19 is involved in the initiation and perpetuation of RA synovitis, leading to joint lesions.

Antigens, Viral↗
PubMed1998

Phase I trial of intraperitoneal iododeoxyuridine with and without intravenous high-dose folinic acid in the treatment of advanced malignancies primarily confined to the peritoneal cavity: flow cytometric and pharmacokinetic analysis.

In this Phase I study, the maximally tolerated doses (MTDs) of i.p. iododeoxyuridine (IdUrd) alone and in combination with i.v. calcium leucovorin (LV) were determined. The pharmacokinetics and pharmacological advantage of IdUrd were evaluated, and flow cytometric analysis allowed examination of the extent of incorporation of IdUrd into tumor cells with and without the addition of i.v. LV. Thirty-nine patients with advanced neoplasms primarily confined to the peritoneal space were enrolled in a dose-escalation trial using 4-h dwells of IdUrd administered i.p. daily for 4 days with and without an i.v. infusion of LV 500 mg/m2/day for 4.5 days. Twenty-three patients received single-agent therapy, and 13 patients received i.p. IdUrd in combination with i.v. LV. The MTD of single-agent IdUrd administered on this schedule was 4125 mg/m2/day for 4 days; and that of the IdUrd in combination was 3438 mg/m2/day. Dose-limiting toxicities were myelosuppression and stomatitis. During the period of the dwell, the peritoneal AUC (area under the curve) of IdUrd exceeded the plasma AUC of IdUrd by one or two orders of magnitude in all patients at all doses tested; there was a possible effect of LV on peritoneal AUC. The geometric mean pharmacological advantage (AUCperitoneal/ AUCplasma) was 181 at 625 mg/m2/day and 90 at 4538 mg/m2/day. Flow cytometric analysis suggests saturation of IdUrd measured in DNA at the 2500-3125 mg/m2 dose level, without an increase after the addition of LV. Twelve patients received 4-12 courses of therapy. One patient with recurrent ovarian cancer who received 16 courses of therapy experienced complete resolution of her ascites, near normalization of CA-125 levels, and improved quality of life; two patients with high-risk tumors receiving "adjuvant" therapy are disease-free at 3 and 6 years after treatment; other patients experienced transient clearing of ascites. The recommended Phase II dose of i.p. IdUrd using a 4-h dwell daily for 4 days is 3750 mg/m2/day alone or 3125 mg/m2/day in combination with continuous i.v. LV at 500 mg/m2/day for 4.5 days. Although flow cytometric data suggest that DNA incorporation of IdUrd is not affected by the addition of LV, the cytotoxicity of the combination regimen may be increased due to LV-enhanced, IdUrd-related inhibition of thymidylate synthase. For this reason, we recommend that efficacy studies of the combination continue in parallel with studies of IdUrd alone.

Adult↗
PubMed1998

Effect of mRNA cap structure on eIF-4E phosphorylation and cap binding analyses using Ser209-mutated eIF-4Es.

The in vitro phosphorylation of human recombinant eIF-4E by protein kinase C was most effective in the absence of m7GTP, supporting a 'performed complex model' as the mRNA binding step of initiation, i. e., eIF-4E first forms an initiation complex eIF-4F and is phosphorylated before interacting with mRNA. On the other hand, the comparison of m7GTP-binding ability of wild-type eIF-4E with those of four Ser209-mutated ones (S209A, S209D, S209E and S209K) showed that the addition of anionic charge on Ser209 increases the cap affinity of eIF-4E by repressing the release of the cap from the complex, not by increasing the complex formation, suggesting the importance of a retractable ionic bridge between Ser209 and Lys159 in controlling the cap binding by eIF-4E phosphorylation.

Binding Sites↗
PubMed1998

Methylcobalamin amplifies melatonin-induced circadian phase shifts by facilitation of melatonin synthesis in the rat pineal gland.

Effects of methylcobalamin (methyl-B12), a putative drug for treating human circadian rhythm disorders, on the melatonin-induced circadian phase shifts were examined in the rat. An intraperitoneal injection of 1-100 microg/kg melatonin 2-h before the activity onset time (CT 10) induced phase advances of free-running activity rhythms in a dose-dependent manner (ED50=1.3 microg/kg). Injection of methyl-B12 (500 microg/kg) prior to melatonin (1 microg/kg) injection induced larger phase advances than saline preinjected controls, while the injection of methyl-B12 in combination with saline did not induce a phase advance. These results indicate amplification of melatonin-induced phase advances by methyl-B12. Pinealectomy abolished the phase alternating effect of methyl-B12, suggesting a site of action within the pineal gland. In fact, methyl-B12 significantly increased the content of melatonin in the pineal collected 2-h after activity onset (CT 14). In contrast, no difference in melatonin content was found at CT 10, indicating that the effect of methyl-B12 may be gated after the activity onset time when endogenous melatonin synthesis is known to increase. These results suggest that methyl-B12 amplifies melatonin-induced phase advances via an increase in melatonin synthesis during the early subjective night at a point downstream from the clock regulation.

Animals↗
PubMed1998

Determination of metallothionein by high-performance liquid chromatography with fluorescence detection using an isocratic solvent system.

Metallothionein (MT) is a low-molecular-weight protein which plays a role in detoxification of heavy metals and protection against oxidative stress. A sensitive and convenient determination method for MT is necessary to clarify its physiological roles. High-performance liquid chromatography (HPLC) with an isocratic solvent system for MT was, therefore, developed utilizing an unique fluorescence labeling reagent, ammonium 7-fluorobenz-2-oxa-1,3-diazole-4-sulfonate (SBD-F). The HPLC system with two separation columns, Shodex RSpak RP18-413 column (a styrene divinylbenzene polymer gel-packed column) and Puresil C18 column (an ODS gel-packed column), connected in tandem successfully separated SBD-labeled MT from biological interference. The SBD-labeled MT was stable and could be stored for at least 1 week without any changes in fluorescence intensity. Although Hg-MT was not detectable, this method is applicable to determination of major MTs such as Zn-MT, Cd-MT, and Cu-MT using commercially available rabbit MT as a standard. Determination of the MT concentration in cells was possible in aliquots of only 1 x 10(4) cultured cells. The present method using a tandem column HPLC system with isocratic elution might be useful for monitoring the concentration of MT in cultured cells as well as in animal tissues.

Animals↗
PubMed1998

N-methyl-D-aspartate receptors are indispensable for the formation of long-term potentiation in the rat suprachiasmatic nucleus in vitro.

Optic nerve (ON) stimulation caused a postsynaptic field potential in the suprachiasmatic nucleus (SCN) of rat hypothalamic slices. The postsynaptic field potential was suppressed by 6-cyano-7-nitroquinoxaline-2,3-dione (CNQX), a non-NMDA receptor antagonist, in a concentration-dependent manner, but not affected by D-amino-5-phosphonovaleric acid (APV), a competitive NMDA receptor antagonist. Tetanic stimulation to the ON induced long-term potentiation (LTP) in the SCN. Application of APV at 50 microM inhibited the induction of LTP by tetanic stimulation but CNQX at lower dose (5 microM) didn't inhibit it. These results suggest that NMDA receptors are indispensable for the induction of LTP after tetanic stimulation.

2-Amino-5-phosphonovalerate↗
PubMed1998

Enhanced engraftment of human peripheral blood lymphocytes into anti-murine interferon-gamma monoclonal antibody-treated C.B.-17-scid mice.

To improve the engraftment of human peripheral blood lymphocytes (PBL) to severe combined immunodeficient (SCID) mice, and to elucidate the factors which prevent the PBL's survival, we treated SCID mice with mAb, which neutralizes murine IFN-gamma's ability to activate cell-mediated immunity. Compared with untreated mice, mAb-treated mice retained significantly higher numbers and ratios of human PBL in the peritoneal cavity and spleen, as well as significantly higher serum titers of human IgG and IgM. Histologically, host versus graft reaction (HVGR) was less severe in the mAb-treated mice. Moreover, these phenomena were completely abrogated when mice were also treated with murine recombinant IFN-gamma. These results suggest that murine IFN-gamma plays an important role in the rejection of human cells in SCID mice and that its depletion by means of mAb treatment can significantly reduce HVGR and improve the engraftment of human PBL.

Animals↗
PubMed1998

In SCID-hu mice, passive transfer of a humanized antibody prevents infection and atrophic change of medulla in human thymic implant due to intravenous inoculation of primary HIV-1 isolate.

Using SCID-hu mice, it was tested whether humanized mAb Rmu5.5 could prevent infection by HIV-1 i.v. inoculation. The Ab that recognizes the IHIGPGRAFYT motif in the principal neutralizing determinant (PND) of HIV(MN), as well as the original mouse mAb mu5.5, neutralized HIV(MN) with high activity. Seven primary field isolates from Japanese hemophiliacs seropositive for HIV-1 clade B were compared for their reactivities to Rmu5.5. Rmu5.5 was effective, particularly against the viruses that matched amino acid sequences of the PND region of HIV-1, and it completely neutralized primary isolates. Moreover, the passive transfer of the Ab elicited protection against challenge by the primary isolates in SCID-hu or hu-PBL-SCID mice after i.v. inoculation with the virus by both quantitative PCR and PBMC-based virus isolation in vitro. Further, inoculation with the Ab also prevented the atrophic change in the medulla of the thymic transplant that was induced by i.v. inoculation of the virus. Thus, the humanized neutralizing Ab Rmu5.5 appears to protect SCID-hu mice from infection by primary field isolates.

Adult↗
PubMed1998

Somatic mutation in autoantibody-associated VH genes of circulating IgM+IgD+ B cells.

Naive B cells expressing IgM and IgD on their surface have no or little somatic mutations in V genes. We have demonstrated that the human IgM+IgD+B cell clone (0-81), which expresses nephritogenic idiotypes, produces IgM anti-DNA antibodies which show monospecificity to DNA. Using a DNA probe which specifically links to the VH gene of antibody 0-81, we identified the counterpart germ-line V gene of 0-81, V3-7, which appears to be used by pathogenic autoantibodies in humans. Clone 0-81, which may belong to naive B cells in terms of cell phenotype, uses a somatically mutated V3-7 gene. We further studied DNA sequences of V3-7 genes in circulating IgM+IgD+B cells from normal subjects and patients with systemic lupus erythematosus (SLE). The results revealed that rearranged V3-7 genes in IgM+IgD+B cells from patients with SLE contained somatically mutated sequences at significantly increased frequencies. These data indicate an abnormal maturation of B cells in autoimmune states that may be associated with an escape of self-reactive B cells from the elimination process in the germinal center.

Amino Acid Sequence↗
PubMed1998

MHV-induced fatal peritonitis in mice lacking IFN-gamma.

IFN-gamma gene was disrupted by homologous recombination in A3-1 embryonic stem cells. Germinally transmitted chimeric mice were successfully obtained and backcrossed with C57BL/6 (B6) mice 5 or 6 times. Deficiency of IFN-gamma in homozygous mice was confirmed by northern blot analysis of spleen cells stimulated with phorbor esther and calcium ionophore and also by IFN-gamma production in the culture supernatant of spleen cells stimulated with the same reagents. B6 mice lacking IFN-gamma were infected intraperitoneally (ip) with 10(6) PFU of JHMV and monitored for their survival. Approximately 90% of the mice died at 50 days post-infection (pi) and the mean survival time was 28 days. Mice sacrificed at 3 weeks pi showed severe peritonitis accompanying the accumulation of a viscous fluid in the abdominal and thoracic cavities. Microscopically, the disease was characterized by disseminated granulomatous inflammation and exudative fibrinous serositis in the abdominal cavity. Infectious virus was isolated in most tissues including the liver, spleen, kidney, pancreas and lung during the experimental periods. The disease was not observed in wild-type or heterozygous littermates infected i.p. with JHMV. These results suggest that IFN-gamma plays a critical role in MHV infection in mice. This experimental model may provide a unique opportunity to address the pathogenesis of virus-induced peritonitis such as feline infectious peritonitis in cats.

Acute Disease↗
PubMed1998

Immunohistochemical analysis of p53 and p21 in human primary glioblastomas in relation to proliferative potential and apoptosis.

The Cdk inhibitor p21/WAF1 can be transcriptionally activated by wild-type p53, not by mutant p53, and functions to block cell-cycle progression in many human neoplasms. We examined the immunohistochemical expression of p53 and p21 in 35 human primary glioblastomas in relation to tumor proliferation potential as assessed by the Ki-67 labeling index (LI) and the glioblastoma apoptosis index (AI). The expression of mutant p53 was observed in 74% of glioblastomas, wild-type p53 in 18% of glioblastomas, and p21 in 57% of glioblastomas. p21 expression was seen in 15 of 26 mutant p53-positive and 2 of 4 wild p53-positive tumors. Tumor Ki-67 LI correlated neither with p53 nor with p21 expression in glioblastomas. Apoptosis was identified in all 15 glioblastomas examined, with a mean (+/-SD) Al of 1.69+/-1.54, and correlated neither with p53 (wild or mutant) nor with p21 expression. The results of the present study suggest that p53 mutation and p21 protein expression are frequent in primary glioblastoma but lack correlation with tumor proliferation potential and apoptosis. The lack of correlation between p21 and p53 also suggests that p21 in glioblastomas may be induced by a p53-independent pathway.

Adult↗
PubMed1998

Contractile and phosphatidylinositol responses of rat trachea to anticholinesterase drugs.

PURPOSE: Some anticholinesterases (anti-ChE) such as neostigmine and pyridostigmine but not edrophonium, stimulate phosphatidylinositol (PI) response. Although a direct relationship was suggested between the increase in PI response and airway smooth muscle contraction, there are no data regarding the effects of anti-ChE drugs on airway smooth muscle. Thus, we examined the contractile properties and PI responses produced by anti-ChE drugs. METHODS: Contractile response. Rat tracheal ring was suspended between two stainless hooks in Krebs-Henseleit (K-H) solution. (1) Carbachol (CCh), anti-ChE drugs (neostigmine, pyridostigmine, edrophonium) or DMPP (a selective ganglionic nicotinic agonist) were added to induce active contraction. (2) The effects of 4-diphenylacetoxy-N-methyl-piperidine methobromide (4-DAMP), an M3 muscarinic receptor antagonist, on neostigmine- or pyridostigmine-induced contraction of rat tracheal ring were examined. (3) Tetrodotoxin (TTX) was tested on the anti-ChE drugs-induced responses. PI response. The tracheal slices were incubated in K-H solution containing LiCl and 3[H]myo-inositol in the presence of neostigmine or pyridostigmine with or without 4-DAMP, an M3 muscarinic receptor antagonist. 3[H]inositol monophosphate (IP1) formed was counted with a liquid scintillation counter. RESULTS: Carbachol (0.1 microM), neostigmine (1 microM), pyridostigmine (10 microM) but not edrophonium or DMPP, caused tracheal ring contraction. 4-DAMP, but not tetrodotoxin, inhibited neostigmine and pyridostigmine-induced contraction. Neostigmine- or pyridostigmine-induced IP1, accumulation was inhibited by 4-DAMP. CONCLUSIONS: The data suggest that anti-ChE drugs activate the M3 receptors at the tracheal effector site.

Animals↗