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Biomedical subjects

Y Koga

Publications and source records attributed to Y Koga.

At least 145 records · Page 8Linked to original sources
PubMed1998

[Evaluation of preincisional mexiletine administration to alleviate postoperative pain].

Mexiletine, an antiarrhythmic agent, was preincisionally administered intravenously for the purpose of reducing postoperative pain. Twenty-eight female patients for mastectomy were studied. The patients were divided into three groups. Group 1 received no mexiletine. Group 2 received bolus administration of mexiletine 1 mg.kg-1 with additional continuous administration of 1 mg.kg-1.hr-1 for 75 minutes. Group 3 received bolus administration of mexiletine 2 mg.kg-1. The requirement of butorphanol as a postoperative analgesic within 1 hour after mastectomy in Group 3 was significantly lower than that in Group 1 (P < 0.05), but butorphanol requirement in Group 2 was not significantly lower than that in Group 1. Plasma mexiletine concentration was slightly higher in Group 3 (1.7 micrograms.ml-1) than that in Group 2 (1.0 microgram.ml-1) immediately after the intravenous mexiletine administration, although there was no significant difference. The results indicate that mexiletine 2 mg.kg-1 as preoperative bolus administration maintains its plasma concentration above 1.7 micrograms.ml-1, and is clinically effective for reducing the postoperative pain after mastectomy.

Adult↗
PubMed1997

F0F1-ATPase genes from an archaebacterium, Methanosarcina barkeri.

It has been known that an archaebacterium Methanosarcina barkeri strain MS (DSM 800) has a V-type ATPase (Inatomi, K., et al. (1989) J. Biol. Chem. 264, 10954-10959). Here, we report cloning of a cluster of F0F1-ATPase genes from the same organism, the first ever found in archaebacteria. The cluster and encoded subunits exhibit several unusual features such that a gene for delta subunit is lacking, F0-b subunit is unusually large, and gamma subunit is split into two peptide fragments. Attempts to detect F0F1-ATPase proteins and mRNA have been unsuccessful and therefore it is not certain if this gene cluster is really expressed in the cell.

Amino Acid Sequence↗
PubMed1997

Nitric oxide mediates murine cytomegalovirus-associated pneumonitis in lungs that are free of the virus.

4 wk after intraperitoneal inoculation of 0.2 LD50 (50% lethal dose) of murine cytomegalovirus (MCMV) in adult BALB/c mice, MCMV remained detectable in the salivary glands, but not in the lungs or other organs. When the T cells of these mice were activated in vivo by a single injection of anti-CD3 monoclonal antibody, interstitial pneumonitis was induced in the lungs that were free of the virus with an excessive production of the cytokines. In the lungs of such mice persistently infected with MCMV, the mRNA of the cytokines such as IL-2, IL-6, TNF-alpha, and IFN-gamma were abundantly expressed 3 h after the anti-CD3 injection, and the elevated levels continued thereafter. A marked expression of inducible nitric oxide synthetase (iNOS) was then noted in the lungs, suggesting that such cytokines as TNF-alpha and IFN-gamma may have induced iNOS. Although the increase in NO formation was demonstrated by the significant elevation of the serum levels of nitrite and nitrate, the interstitial pneumonitis was not associated with either increased superoxide formation or peroxynitrite-induced tyrosine nitration. Nevertheless, the administration of an NO antagonist also alleviated the interstitial pneumonitis provoked by anti-CD3 mAb. Based on these findings, it was concluded that MCMV-associated pneumonitis is mediated by a molecule of cytokine-induced NO other than peroxynitrite.

Animals↗
PubMed1997

Selection of prognostic factors of acute hepatitis type non-A, non-B for patient listing for liver transplantation.

The aim of this study was to select prognostic factors from information available on admission in order to list patients for liver transplantation before the onset of hepatic encephalopathy in patients with fatal hepatitis type non-A, non-B. Information regarding patient profile and biochemical data obtained on admission was analyzed by multiple stepwise logistic regression, and independent prognostic factors related to death were selected. Four parameters were selected as independent prognostic factors. Patient age (over 50 years), serum total bilirubin level (over 10 mg/dl), peripheral leukocyte count, and prothrombin time were independently related to death. Positive predictive value, negative predictive value, and predictive accuracy were 0.86, 0.79, and 0.84, respectively. Our model is able to predict a patient's fatal outcome much earlier than other currently used models. It will be helpful for early referral to a transplant center.

Adult↗
PubMed1997

The requirement of intestinal bacterial flora for the development of an IgE production system fully susceptible to oral tolerance induction.

The role of intestinal bacterial flora in oral tolerance induction to the IgE response was investigated using germfree (GF) mice. When GF mice were orally administered 20 mg of OVA as tolerogen before a systemic challenge with OVA, the Th1-mediated responses, such as the production of IgG2a and IFN-gamma, were abrogated, while the Th2-mediated immune responses, such as the production of IgE, IgG1, and IL-4, were maintained. Moreover, the basal level of IL-4 production in vitro was significantly higher in the GF mice than that of IL-4 in specific pathogen-free mice when challenged systemically with OVA. On the other hand, both Th1 and Th2 responses were fully sensitive to such tolerance induction in specific pathogen-free mice. The reconstitution of intestinal flora of GF mice with Bifidobacterium infantis, one of the predominant bacteria in the intestinal flora, restored the susceptibility of these Th2 responses to oral tolerance induction; however, this was only effective when such reconstitution was performed in neonates, but not in mice at an older age. These results thus suggested that intestinal bacterial flora play a crucial role in generating a Th2 cell population whose size and response are adequately regulated and, consequently, fully susceptible to oral tolerance induction, probably by affecting the development of gut-associated lymphoid tissue at the neonatal stage.

Administration, Oral↗
PubMed1997

Fas-mediated apoptosis of the hematopoietic progenitor cells in mice infected with murine cytomegalovirus.

The effects of cytomegalovirus (CMV) infection on hematopoietic progenitor cells in vivo were investigated to elucidate the pathogenesis of CMV-induced myelosuppression. BALB/c mice were inoculated with 0.2LD50 of murine CMV (MCMV). Lineage marker negative, c-kit positive (Lin-c-kit+) and Lin-CD34+ cells, which are both phenotypically defined as hematopoietic progenitor cells, showed a significant reduction in number on day 3 postinfection (pi). Moreover, the reduction in the number of day-14 colony-forming units-spleen (CFU-S), another indicator to identify hematopoietic progenitor cells, was noted on day 3 pi. To clarify the mechanism of such depletion, we examined the cells undergoing apoptosis in the Lin- populations and found a 15-fold increase in the apoptosis-induction of these cells. Furthermore, an increase in the expression level of Fas, which mediates apoptosis, was observed in such Lin-c-kit+ and Lin-Sca-1+ cells on day 3 pi. In vitro treatment with the anti-Fas antibody accelerated the apoptosis in Lin- cells, but not in the uninfected control cells, thus indicating that the upregulated Fas on Lin- cells is directly related to the acceleration of apoptosis found in these cells in vivo. These results suggest that MCMV infection reduces the number of hematopoietic progenitor cells in bone marrow at least in part due to Fas-mediated apoptosis, and this phenomenon is thus considered to contribute to CMV-induced myelosuppression.

Animals↗
PubMed1997

Mass spectrometric gene diagnosis of one-base substitution from polymerase chain reaction amplified human DNA.

One-base substitution has been detected on the polymerase chain reaction (PCR) products amplified from human mutated DNA for the first time by using mass spectrometry. PCR fragments of 52 base pairs were produced on a collagen gene of an osteogenesis imperfecta patient's heterozygous DNAs. The products were digested with EcoRI restriction enzyme to liberate 3'-end adducts and purified by phenol + chloroform extraction, ammonium acetate addition and ethanol precipitation to remove sodium ions from the phosphoric acid backbone of the DNAs. Purified products were examined using an electrospray ionization mass spectrometer. Mass spectra showed four groups of fragment peaks with the expected molecular masses, which originate from the sense and antisense strands of the heterozygous DNAs.

Base Sequence↗
PubMed1997

Growth of tracheal autografts in puppies.

The growth of tracheal autografts and the patency of anastomotic regions were studied in 11 mongrel puppies (2.5-4 months of age, 1.9-4.3 kg in weight). Thoracic tracheal autotransplantation of 7 cartilage rings was performed. The tracheal autografts and anastomotic regions were covered with an omental pedicle flap to facilitate revascularization. Seven of the 11 dogs were evaluated for 12 months. The cross-sectional area of the lumen at the center of the tracheal autograft, as measured by thoracic computed tomography (CT), showed a significant increase from 0.37 +/- 0.11 cm2 to 1.13 +/- 0.44 cm2 after 12 months (P < 0.05). At 12 months postoperatively, all of the experimental dogs were killed, their entire tracheas were resected, and the cross-sectional areas of the anastomosis on the proximal and distal sides were measured. The cross-sectional areas at sites 5 mm apart from both anastomoses in the ungrafted trachea were measured as controls. The percent cross-sectional area (%CSA) showed good values of 67.2% +/- 19.6% on the proximal side and 85.1% +/- 12.6% on the distal side. The tracheal autografts appeared both visually and histologically viable 12 months postoperatively. This study was able to demonstrate the growth potential of the tracheal autograft in a growing puppy model.

Age Factors↗
PubMed1997

Prenatal diagnosis of congenital unilateral hydrocephalus.

A case is presented in which fetal unilateral hydrocephalus that had not been definitively diagnosed by ultrasonography was confirmed by means of magnetic resonance imaging. Computed tomography performed in the neonatal period after intraventricular injection of contrast medium showed stenosis of the foramen of Monro.

Adult↗
PubMed1997

Fas ligand-mediated depletion of CD4 and CD8 lymphocytes by monomeric HIV-1-gp120.

In order to determine in what condition and by what mechanism gp 120 can deplete not only CD4 but also CD8 T cells, an in vitro system was established in which peripheral blood lymphocytes from healthy donors were treated with recombinant gp 120. We found that gp 120 can deplete both CD4 and CD8 T cells when they have recently been activated and are exposed to IL-2-deficient conditions. Bioassay of the Fas ligand (FasL) demonstrated augmented expression and release of soluble FasL by CD4 T cells in the supernatant of this culture. The administration of anti-FasL mAb and anti-Fas mAb, both of which exhibit neutralizing activity, completely abolished the depletion of these two T cell populations in culture. Based on these findings, we concluded that FasL depletes Fas antigen expressing CD4 and CD8 T cells by programmed cell death.

Antibodies, Monoclonal↗
PubMed1997

Basal cell carcinoma developing on a burn scar.

Basal cell carcinoma occurring on a burn scar is quite care. However, when it does occur, it is usually seen on sites exposed to the sun or on sites with embryological closure lines. A case of basal cell carcinoma which developed on a burn scar on the trunk is described. The injury was from a flame burn which occurred more than 50 years ago. No mechanical irritation had occurred on the lesion since then.

Aged↗
PubMed1997

Mutations in the cardiac troponin I gene associated with hypertrophic cardiomyopathy.

Hypertrophic cardiomyopathy (HCM), the most common cause of sudden death in the young, is an autosomal dominant disease characterized by ventricular hypertrophy accompanied by myofibrillar disarrays. Linkage studies and candidate-gene approaches have demonstrated that about half of the patients have mutations in one of six disease genes: cardiac beta-myosin heavy chain (c beta MHC), cardiac troponin T (cTnT), alpha-tropomyosin (alpha TM), cardiac myosin binding protein C (cMBPC), ventricular myosin essential light chain (vMLC1) and ventricular myosin regulatory light chain (vMLC2) genes. Other disease genes remain unknown. Because all the known disease genes encode major contractile elements in cardiac muscle, we have systematically characterized the cardiac sarcomere genes, including cardiac troponin I (cTnI), cardiac actin (cACT) and cardiac troponin C (cTnC) in 184 unrelated patients with HCM and found mutations in the cTnI gene in several patients. Family studies showed that an Arg145Gly mutation was linked to HCM and a Lys206Gln mutation had occurred de novo, thus strongly suggesting that cTnI is the seventh HCM gene.

Actins↗
PubMed1997

Purification and properties of sn-glycerol-1-phosphate dehydrogenase from Methanobacterium thermoautotrophicum: characterization of the biosynthetic enzyme for the enantiomeric glycerophosphate backbone of ether polar lipids of Archaea.

The enzyme which seems to be responsible for the formation of the enantiomeric configuration of the glycerophosphate backbone (sn-glycerol-1-phosphate) of archaeal ether lipids was purified from a methanogenic archaeon, Methanobacterium thermoautotrophicum, and characterized. The enzyme, sn-glycerol-1-phosphate: NAD(P)+ oxidoreductase (sn-glycerol-1-phosphate dehydrogenase), was purified 7,600-fold from a cell free extract by ammonium sulfate fractionation and seven steps of chromatography. The final preparation exhibited a specific activity of 617 micromol/min/mg (Vmax) and gave a single band corresponding to 38 kDa on polyacrylamide gel electrophoresis in the presence of sodium dodecyl sulfate. The native enzyme showed an apparent molecular mass of 302 kDa on gel-filtration chromatography, indicating it is present as a homooctamer. Maximum activity was observed at 75 degrees C at near neutral pH. The activity was stimulated by potassium ions. The Km for dihydroxyacetone phosphate was 7.5 times smaller than that for sn-glycerol-1-phosphate, suggesting that the formation of sn-glycerol-1-phosphate is the natural direction in the cell. Under the assay conditions used, no product inhibition was observed. The N-terminal amino acid sequence was determined.

Amino Acid Sequence↗
PubMed1997

Cytotoxicity and motility of Helicobacter pylori.

To clarify the relationship between interleukin-8 (IL-8) production and virulent factors, we examined the motility and cytotoxicity of H. pylori, suggested to be a major cause of chronic gastritis and peptic ulcers. Our results demonstrated that among cytotoxic strains of H. pylori, high-motility strains induced more IL-8 than low-motility strains. There was no correlation between cytotoxicity and motility of H. pylori. Four restriction fragment length polymorphism (RFLP) patterns were observed in the flaA PCR products. There was no correlation between flaA RFLP and motility. In conclusion, our findings suggest that both cytotoxicity and motility are virulent factors in the pathogenesis of gastric mucosal injury.

Animals↗
PubMed1997

Analysis of interleukin-8 secretion induced by Helicobacter pylori from the gastric epithelial cell line MKN45: a mechanism independent of the intensity of cytotoxicity.

Interleukin (IL)-8, a potent chemoattractant and activator of neutrophils, has been implicated to have a major role in the pathogenesis of gastric mucosal injury by Helicobacter pylori infection. We examined the relationship between cytotoxicity and IL-8 secretion induced by H. pylori. Furthermore, whether the vacuolating cytotoxin of H. pylori mediates IL-8 secretion from gastric epithelial cell lines was examined. Among the inflammatory cytokines, messages for IL-6, IL-8 and transforming growth factor-beta 1 were produced by gastric cancer (MKN45) cells in response to exposure to the cytotoxic strain of H. pylori. MKN45 incubated with the viable cytotoxic strain of H. pylori secreted IL-8. In contrast, the supernatant of neither the cytotoxic nor the non-cytotoxic strain induced IL-8 secretion. There was no correlation between IL-8 secretion and the intensity of cytotoxicity. In conclusion, these findings suggest that IL-8 secretion from MKN45 induced by H. pylori is mediated by factors other than cytotoxicity.

Bacterial Proteins↗
PubMed1997

Prevention of Helicobacter pylori infection by lactobacilli in a gnotobiotic murine model.

BACKGROUND: Helicobacter pylori is a bacterium which causes gastric inflammatory diseases. Oral inoculation of H pylori usually results in only a temporary colonisation without a successful infection in the stomach of conventional mice in which lactobacilli are the predominant indigenous bacteria. AIM: To determine whether lactobacilli exert an inhibitory effect on colonisation by H pylori in the stomach. METHODS: The effects of H pylori on attachment to murine and human gastric epithelial cells and the H pylori mediated release of interleukin-8 (IL-8) by these cells were examined in vitro. Lactobacillus salivarius infected gnotobiotic BALB/c mice and control germ free mice were inoculated orally with H pylori to examine whether L salivarius can inhibit colonisation by H pylori. RESULTS: L salivarius inhibited both the attachment and IL-8 release in vitro. H pylori could not colonise the stomach of L salivarius infected gnotobiotic BALB/c mice, but colonised in large numbers and subsequently caused active gastritis in germ free mice. In addition, L salivarius given after H pylori implantation could eliminate colonisation by H pylori. CONCLUSION: These findings suggest the possibility of lactobacilli being used as probiotic agents against H pylori.

Animals↗