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Biomedical subjects

K Shibata

Publications and source records attributed to K Shibata.

At least 235 records · Page 13Linked to original sources
PubMed1997

Cellular immuno-competence of infected root canal contents in pathogenesis of periapical lesions.

The soluble fractions of infected root canal contents (IRCC) were collected from about 300 human extracted teeth and examined for the presence of mononuclear cell (MNC) chemotaxis and cellular immunocompetence. IRCC showed remarkable chemotactic activity for polymorphonuclear leukocytes but a weak activity for MNC. However, generation of intrinsic MNC chemotaxis and induction of cellular immunity were confirmed in rats given repeated injections of IRCC.

Animals↗
PubMed1997

Increased matrix metalloproteinase-9 activity in human ovarian cancer cells cultured with conditioned medium from human peritoneal tissue.

Ovarian cancer cells disseminate by attachment to the peritoneal mesothelial cell surface of the abdominal cavity. We therefore investigated the influence of conditioned medium (CM) from human peritoneal tissues and mesothelial cells on the secretion of matrix metalloproteinases (MMPs) by ovarian cancer cells. The molecular weights of MMPs stimulating factors derived from human peritoneal tissues and mesothelial cells were estimated using microconcentrators with various cut-off membranes. Human peritoneal tissues were obtained from 12 surgical patients, and mesothelial cells were isolated from three peritoneal specimens. Exposure to CM from peritoneal tissue caused a concentration-dependent increase of the MMP-2 and MMP-9 bands in CM from NOM1 ovarian cancer cells, as shown by zymography. There was a significant difference in the increase of MMP-2 and MMP-9 (2.46-fold and 7.14-fold, respectively, at 0.4 mg/ml protein; P < 0.005). CM from mesothelial cells also significantly increased the secretion of MMP-9 by NOM1 cells. The molecular size of possible MMP-9-stimulating factors secreted by peritoneal tissues and mesothelial cells was above M(r) 100000. Further, CM of peritoneal tissues and mesothelial cells also induced the invasiveness of NOM1 cells. These findings suggest that mesothelial cells may secrete some factors which predominantly induce the MMP-9 production and increase invading cell numbers.

Collagenases↗
PubMed1997

Simultaneous recording of pattern reversal electroretinograms and visual evoked potentials in migraine.

We recorded full-field pattern reversal electroretinograms (PERGs) and visual evoked potentials (PVEPs) simultaneously in 15 migraine with aura, 14 migraine without aura patients during the interictal period, and in 23 sex- and age-matched normal subjects. All subjects had normal visual fields. The visual aura in all patients was hemianopsia or fortification spectra. Neither migraine group showed significant differences from normal in latency and amplitude of PERGs. In migraine with aura, the amplitudes of PVEPs in classic migraine at the mid-occipital electrode were significantly (p < 0.01) higher than normal. PVEP amplitudes were significantly (p < 0.01) higher on the contralateral side of the aura than the ipsilateral side in both visual aura and normal subjects, but there was no significant difference in latency. This high amplitude and asymmetry of PVEPs may contribute to defective inhibition between interhemispheric visual occipital areas or striate and peristriate areas.

Adult↗
PubMed1997

Substrate-binding and catalytic roles of Lys194 in the C-terminus in human adenylate kinase by site-directed random mutagenesis.

Site-directed random mutagenesis of Lys194 residue in the C-terminus of human adenylate kinase (AK) was performed, and six mutants were analyzed by steady-state kinetics. K194-mutants variously affected the apparent Michaelis constants (K(m) values) for ATP and AMP, although the kcat values strikingly decreased. The Lys194 residue appears to interact not only with MgATP2- but also with the AMP2- substrates by salt bridge formation with a nucleotide and to play a functional role in stabilizing the phosphate-transfer during catalysis. Lys194 could be essential for substrate-holdings and in catalysis and not replaceable to the other amino acids.

Adenylate Kinase↗
PubMed1997

Predicting difficult intubation with indirect laryngoscopy.

BACKGROUND: It is not always possible to predict when tracheal intubation will be difficult or impossible. The authors wanted to determine whether indirect laryngoscopy could identify patients in whom intubation was difficult. METHODS: Indirect laryngoscopy was done in 2,504 patients. The Wilson risk sum score and the modified Mallampati score were also studied in a different series of 3,680 patients for comparison. These predictive methods were compared according to three parameters: positive predictive value, sensitivity, and specificity. RESULTS: Of 6,184 patients studied, the trachea proved difficult to intubate in 82 (1.3%). Positive predictive value (31%) and specificity (98.4%) with indirect laryngoscopy were greater than the other two predictive methods (P < 0.01), whereas sensitivity with indirect laryngoscopy (69.2%) was greater than that of the Wilson risk sum score (55.4%) (P < 0.01). CONCLUSIONS: Although in 15% of patients indirect laryngoscopy could not be performed because of excessive gag reflex, indirect laryngoscopy can serve as an effective method to predict difficult intubation.

Adult↗
PubMed1997

Potentiation of dipsogenic actions by centrally administered type-C natriuretic peptide in spontaneously hypertensive but not Wistar-Kyoto rats.

1. The effects of type-C natriuretic polypeptides (CNP) on the central dipsogenic and pressor responses to angiotensin II (AngII) were studied by the administration of agents into the lateral cerebral ventricle under conscious and unrestrained conditions in normotensive Wistar-Kyoto (WKY) and spontaneously hypertensive rats (SHR). 2. The fluid intake induced by AngII (25 ng) and water deprivation were potentiated after pretreatment with CNP in SHR but not in WKY rats. However, carbachol-induced water intake was not altered by pretreatment with CNP (2.5 micrograms) in either WKY rats or SHR. 3. In contrast, CNP did not influence the pressor responses to AngII in either WKY rats or SHR.

Angiotensin II↗
PubMed1997

Mycoplasma fermentans enhances concanavalin A-induced apoptosis of mouse splenic T cells.

Mycoplasma fermentans, an AIDS-associated mycoplasma, possessed the activity of enhancing concanavalin A-induced apoptosis of T cells purified from mouse spleen by a nylon wool column, and tumor necrosis factor-alpha played an important role in expression of the activity. M. salivarium, an oral mycoplasma, used for comparative purposes also possessed the activity, the level of which was lower than that of M. fermentans.

Animals↗
PubMed1997

Mycoplasma salivarium induces interleukin-6 and interleukin-8 in human gingival fibroblasts.

Analysis by an enzyme-linked immunosorbent assay for cytokines indicated that whole cells, intracellular materials and cell membranes of Mycoplasma salivarium induced interleukin-6 and interleukin-8 in a human gingival fibroblast cell line, Gin-1 cells. This was confirmed by reverse transcription-polymerase chain reaction analysis of mRNAs of these cytokines. Studies with inhibitors of second-messenger pathway indicated that a protein kinase C-dependent pathway was involved in the expression of the activity of the cell membranes. In addition, whole cells of other mycoplasmas (M. hominis, M. arthritidis, M. arginini, M. fermentans, M. penetrans, M. pirum and M. pneumoniae) tested for comparative purposes were also shown to possess the activity. Thus, this study demonstrated that mycoplasmas possess the activity to induce interleukin-6 and interleukin-8 in human fibroblasts.

1-(5-Isoquinolinesulfonyl)-2-Methylpiperazine↗
PubMed1997

Therapeutic efficacy of BO-3482, a novel dithiocarbamate carbapenem, in mice infected with methicillin-resistant Staphylococcus aureus.

The in vivo activity of BO-3482, which has a dithiocarbamate chain at the C-2 position of 1beta-methyl-carbapenem, was compared with those of vancomycin and imipenem in murine models of septicemia and thigh infection with methicillin-resistant Staphylococcus aureus (MRSA). Because BO-3482 was more susceptible than imipenem to renal dehydropeptidase I in a kinetic study of hydrolysis by this renal enzyme, the therapeutic efficacy of BO-3482 was determined during coadministration with cilastatin. In the septicemia models, which involved two homogeneous MRSA strains and one heterogeneous MRSA strain, the 50% effective doses were, respectively, 4.80, 6.06, and 0.46 mg/kg of body weight for BO-3482; 5.56, 2.15, and 1.79 mg/kg for vancomycin; and >200, >200, and 15.9 mg/kg for imipenem. BO-3482 was also as effective as vancomycin in an MRSA septicemia model with mice with cyclophosphamide-induced immunosuppression. In the thigh infection model with a homogeneous MRSA strain, the bacterial counts in tissues treated with BO-3482-cilastatin were significantly reduced in a dose-dependent manner compared with the counts in those treated with vancomycin and imipenem-cilastatin (P < 0.001). These results indicate that BO-3482-cilastatin is as effective as vancomycin in murine systemic infections and is more bactericidal than vancomycin in local-tissue infections. The potent in vivo activity of BO-3482-cilastatin against such MRSA infections can be ascribed to the good in vitro anti-MRSA activity and improved pharmacokinetics in mice when BO-3482 is combined with cilastatin and to the bactericidal nature of the carbapenem.

Animals↗
PubMed1997

Isolation and characterization of Enterobacter cloacae mutants which are defective in chemotaxis toward inorganic phosphate.

Enterobacter cloacae IFO3320 is attracted to Pi when cells are starved for Pi. Two Tn1737KH-induced mutants, which were constitutive for alkaline phosphatase, failed to exhibit Pi taxis even under conditions of Pi limitation. Both of the mutant strains exhibited normal chemotactic responses to peptone, suggesting that they are specifically defective in Pi taxis. Cloning and sequence analysis showed that the TN1737KH insertions were located in either the pstA or pstB genes which encode the channel-forming proteins of the Pi-specific transport (Pst) system in E. cloacae. These results suggest that the E. cloacae Pst system is required for Pi chemoreception.

ATP-Binding Cassette Transporters↗
PubMed1997

Synthesis and opiate activity of pseudo-tetrapeptides containing chiral piperazin-2-one and piperazine derivatives.

Enantiomeric piperazin-2-one derivatives, N,N'-ethylene-bridged alanylphenylalanines (1a or 1b), were synthesized using (S)- or (R)-alanine and phenylalanine as starting materials, and were inserted into the second and third positions of enantiomeric pseudo-tetrapeptides (P1a- or P1b-OEt). The corresponding piperazine derivatives (1a- or 1b-sRed) obtained by selective BH3 reduction of the amide carbonyl groups of 1a or 1b were similarly inserted into the same positions of tetrapeptides (P1a- and P1b-sRed). Enantiomeric N,N'-ethylene-bridged tyrosyltyrosine derivatives (2a or 2b) obtained from (S)- or (R)-tyrosine were also inserted into the first and second positions of two pairs of enantiomeric tetrapeptides (P2a- and P2b-OEt or P'2a- and P'2b-OEt). The opiate activities of the eight peptides thus obtained were studied by use of the mouse vas deferens and the guinea pig ilcum assays in order to elucidate the structure-activity relationships of these peptides, especially with respect to stereochemistry.

Alanine↗
PubMed1997

Effects of sex hormones on the metabolism of tryptophan to niacin and to serotonin in male rats.

It is known that deaths attributable to pellagra, which is considered to be a disease caused by the disturbance of tryptophan metabolism, have been approximately two-fold higher in women than in men. We investigated the effects of the administration of female and male sex hormones on the contents of tryptophan and such metabolites as serotonin, nicotinamide, N1-methylnicotinamide, N1-methyl-2-pyridone-5-carboxamide, and N1-methyl-4-pyridone-3-carboxamide, and on the conversion ratio of tryptophan to niacin in male rats. Feeding a diet containing estrone or testosterone had no effect on the concentrations of tryptophan and serotonin in the blood and brain, or on the concentration of 5-hydroxyindole-3-acetic acid in the brain. On the contrary, feeding a diet containing estrone caused to a decrease in the urinary excretion of nicotinamide, N1-methylnicotinamide, N1-methyl-2-pyridone-5-carboxamide, and N1-methyl-4-pyridone-3-carboxamide, and of the conversion ratio of tryptophan to niacin when compared with the control rats. Feeding a diet containing testosterone had no effect on any parameter. We postulate from these findings that the cause of higher pellagra deaths in women than in men is attributable to the decrease in the formation of niacin from tryptophan, but not in the formation of serotonin by the female hormone. It seems likely that female sex hormones inhibit the synthesis of niacin from tryptophan, and that women, especially during pregnancy, will be more at risk to pellagra than are men.

Animals↗
PubMed1997

Effects of dietary pyrazinamide on the metabolism of tryptophan to niacin in streptozotocin-diabetic rats.

We investigated the effects of feeding with a diet containing pyrazinamide (PYR) on the metabolism of L-tryptophan (Trp) to nicotinamide in streptozotocin (STZ)-diabetic rats and whether the diabetic action of STZ is prevented by feeding with the PYR diet, which is known as an inhibitor of aminocarboxymuconate-semialdehyde decarboxylase and poly(ADP)ribose synthetase and therefore, significantly increases the formation of nicotinamide from Trp in normal rats. As was expected, feeding with the PYR diet to the STZ-injected rats caused a significantly increased excretion of nicotinamide and its metabolites like that in normal rats. The body weight increased in the STZ-injected rats fed with the PYR diet, while it was lost in the STZ-injected rats fed with the non-PYR diet. However, the blood glucose level and the urinary excretion of glucose were not improved even when the rats were fed with the PYR diet. Therefore, it was suggested that chronically increasing the formation of nicotinamide from Trp could not completely prevent the STZ-diabetic action.

Animals↗
PubMed1997

Increased stability of PEG-PPG conjugated human urokinase against autolysis.

Human urokinase (UK) was easily degraded during the incubation at 37 degrees C in a time-dependent manner. The degradation was also observed in the presence of trypsin inhibitors, suggesting that UK was not degraded by exogeneous trypsin-like serine protease but by autolysis. In this cases, the A-chain of UK was selectively degraded. Polyethylene glycol-polypropylene glycol conjugated urokinase (PEG-PPG-UK) was not degraded after prolonged incubation at 37 degrees C. These results demonstrated that PEG-PPG modification completely blocked the degradation of UK by autolysis.

Autolysis↗
PubMed1997

Protein crystallization in microgravity.

A space experiment involving protein crystallization was conducted in a microgravity environment using the space shuttle "Endeavour" of STS-47, on a 9-day mission from September 12th to 20th in 1992. The crystallization was carried out according to a batch method, and 5 proteins were selected as flight samples for crystallization. Two of these proteins: hen egg-white lysozyme and co-amino acid: pyruvate aminotransferase from Pseudomonas sp. F-126, were obtained as single crystals of good diffraction quality. Since 1992 we have carried out several space experiments for protein crystallization aboard space shuttles and the space station MIR. Our experimental results obtained mainly from hen egg-white lysozyme are described below, focusing on the effects of microgravity on protein crystal growth.

Crystallization↗
PubMed1997

Change of tryptophan-niacin metabolism in D-galactosamine-induced liver injury in rat.

The change of tryptophan-niacin metabolism in D-galactosamine (D-galN) injected rats was investigated. Rats fed with niacin-free diets containing 40% casein for 11 days were injected with D-galN (0.8 g/kg body weight). The urinary excretions of nicotinamide and its metabolites, and the activity of liver alpha-amino-beta-carboxymuconate-epsilon-semialdehyde decarboxylase (ACMSD) (EC 4.1.1.45), a key enzyme of tryptophan-niacin metabolism, were assayed. As the result, the urinary excretions of N1-methylnicotinamide (MNA), N1-methyl-2-pyridone-5-carboxamide (2-Py), N1-methyl-4-pyridone-3-carboxamide (4-Py) and their sum (nicotinamide+MNA+2-Py+4-Py) were higher in the D-galN-injected group than in the control group. Hepatic ACMSD activity in the D-galN-injected group was lower than that of the control group. These results suggest that the increase in urinary excretion of nicotinamide and its metabolites after the injection of D-galN is considered to be attributable to a decrease in liver ACMSD activity.

Alanine Transaminase↗