Search PubMed⌕ Search

Biomedical subjects

T Kawaguchi

Publications and source records attributed to T Kawaguchi.

At least 199 records · Page 11Linked to original sources
PubMed1996

Cloning of a cluster of chitinase genes from Aeromonas sp. No. 10S-24.

A gene encoding chitinases from Aeromonas sp. No. 10S-24 was cloned into Escherichia coli DH5 alpha using pUC19, and its nucleotides were sequenced. The chitinase gene was clustered in ORFs (open reading frame) 1 to 4, in a 8-kb fragment of DNA. ORF-1 consisted of 1608 bp encoding 535 amino acid residues, and ORF-2 consisted of 1425 bp encoding 474 amino acid residues. ORF-3 was 1617 bp long and encodes a protein consisting of 538 amino acids. ORF-4 encodes 287 amino acids of the N-terminal region. The amino acid sequences of ORF-1 and ORF-3 share sequence homology with chitinase D from Bacillus circulans, and chitinase A and B from Streptomyces lividans. The amino acid sequence of ORF-2 shared sequence homology with chitinase II from Aeromonas sp. No. 10S-24, and chitinase from Saccharopolyspora erythraea. A region of the sequence starting from Ala-28 of the amino acid sequence of ORF-3 coincided with the N-terminal amino acid sequence of chitinase III from Aeromonas sp. No. 10S-24.

Aeromonas↗
PubMed1996

Long-term follow-up of the residual intracanalicular tumours after subtotal removal of acoustic neurinomas.

We examined growth potential of residual intracanalicular tumours left from subtotal removal of large acoustic neurinomas. Eleven patients were followed-up by magnetic resonance (MR) imaging. The interval between surgery and MR study ranged from 12 to 29 years (median, 16 years). MR images of two patients showed no evidence of tumour remnant, and in six a small tumour was localized in the internal auditory canal. The other three showed an intracanalicular tumour protruding slightly towards the intracranial portion. This result suggests that the intracanalicular residual tumours have less risk of regrowth after subtotal removal of acoustic neurinomas. It is advisable to choose intracapsular, subtotal removal without opening the internal auditory canal in the treatment of acoustic neurinoma, if it is large in size and there is a high risk of nerve injury.

Adult↗
PubMed1996

Cystic acoustic neurinomas: studies of 14 cases.

Cystic acoustic neurinomas (ANs) are less frequent and are different from solid ANs in clinical and radiological features. We had 14 cystic ANs (13.5% of 104 cases) in the last 17 years. Computerized tomographic or magnetic resonance images allowed for the classification of these cystic ANs into three types: Type A being large single cysts with a thin tumourous wall (7 cases); type B single cysts with a thick tumourous wall (3 cases); type C multicystic (4 cases). Half of the cystic ANs were not accompanied by enlargement of the internal auditory canal, despite the largeness of the cysts. The mean size of the tumours was 29 mm in diameter. Type A cysts had a shorter clinical history than types B and C. One patient had intact hearing. In five cases, an atypical initial symptom such as facial pain, dysgeusia, facial palsy, unsteadiness or vertigo presented. The trigeminal nerve was involved in 12 cases, the facial nerve in nine. The characteristic features of cystic ANs are largeness of the tumour, a short clinical history, an atypical initial symptom, facial nerve involvement, and/or no enlargement of the internal auditory canal. In addition, the histological features are a lobular growth pattern, high nuclear atypia, and numerous macro phages.

Adult↗
PubMed1996

An accelerated increase of plasma adrenomedullin in acute asthma.

A novel vasorelaxant peptide, adrenomedullin (AM), has been isolated from the acid extract of human pheochromocytoma. We have recently shown that AM inhibits histamine- and acetylcholine-induced bronchoconstriction in anesthetized guinea pigs in vivo, and this bronchodilatory effect is long-lasting. Here, we measured plasma AM concentrations in nine patients with an acute attack of bronchial asthma. The results were compared with values in 30 age-matched normal control subjects and seven age-matched stable asthmatic patients. The mean AM concentrations of patients with an acute asthma attack (98 +/- 22 pg/mL) were clearly higher than those of normal control subjects (18 +/- 2 pg/mL) and stable asthmatic patients (21 +/- 3 pg/mL). Reverse-phase high-performance liquid chromatography (HPLC) showed that the major component of plasma immunoreactive AM in patients with an asthma attack and in normal subjects equally corresponded to authentic human AM(1-52). Our results suggest that plasma AM is markedly increased in many of the patients during an acute attack of bronchial asthma, but it is not observed in stable asthmatic patients. Although this report is preliminary, the observed increase of circulating AM during an acute asthma attack may represent a compensatory mechanism against the bronchoconstriction, probably through its bronchodilatory action.

Acute Disease↗
PubMed1996

Synthetic nucleosides and nucleotides. 37. Antisense oligodeoxynucleotides bearing 5-(phenylethyl)-2'-deoxyuridylate at the 3'-terminus: exonuclease-resistant molecule with natural phosphodiester backbone.

5-(Phenylethyl)-2'-deoxyuridine has been incorporated into an oligodeoxynucleotide (ODN) by using normal cyanoethyl phosphoramidite chemistry on a DNA synthesizer. For introduction of the modified residue at the 3'-end position of the ODN, we designed and synthesized a new nucleoside phosphoramidite derivative, which connected the 3'-hydroxyl group and phosphoramidite moiety by an alkaline-labile linker. The 3'-end could be substituted in ODNs by using commercially available supports as a starting material following standard NH4OH treatment. The ODN carrying 5-(phenylethyl)-2'-deoxyuridine at the 3'-end position showed about 3-fold resistance to nucleolytic degradation in human plasma without precluding its specific base-pairing activity.

Deoxyuridine↗
PubMed1996

Expression of carbohydrate-binding protein p33/41 in human tumor cell lines.

We previously reported a new type of lectin, p33/41 (annexin IV), which was isolated from a bovine tissue extract [Kojima, K. et al. (1992) J. Biol. Chem. 267, 20536-20539]. When the expression of p33/41 (annexin IV) was surveyed in the lysates of 39 human tumor cell lines by SDS-PAGE, followed by Western blot analysis with polyclonal anti-bovine p33/41 and monoclonal anti-annexin IV (Z016, Zymed) antibodies, 21 cell lines were found to be reactive with the polyclonal antibody, whereas all 39 cell lines were stained with Z016. These results together with those obtained with standard proteins, annexins IV and V, suggested that the monoclonal antibody, Z016, recognizes annexin V, but not p33/41 (annexin IV). Therefore, we performed cDNA cloning of human p33/41 (annexin IV) to prepare a recombinant protein and raised monoclonal antibodies against the protein. Northern blot analysis with the cDNA as a probe showed that a human colon cancer cell line, HT29, contains p33/41 (annexin IV) mRNA of two sizes, 2.0 and 3.0 kb. The two monoclonal antibodies, AS11 and AS17, against the recombinant protein generated were useful for flow cytometric analysis, ELISA, Western blot analysis and immunoprecipitation. Flow cytometric analysis with AS17 showed that p33/41 (annexin IV) is located in the cytoplasm of HT29 cells, but not on the cell surface. However, one of the cell surface proteins first labeled with biotin and then solubilized with a detergent was immunoprecipitated with AS17. The results suggest the existence of a membrane spanning form of p33/41 (annexin IV).

Adenocarcinoma↗
PubMed1996

X-ray diffraction pattern from internal structure of bovine rhodopsin.

Pure bovine rhodopsin pellets were prepared by removal of cholic acid from rhodopsin-cholic acid complex, and X-ray diffraction patterns from the internal structure of rhodopsin were obtained for the first time using wet and dry pellet samples. The peaks at around 10 and 4.3 A spacings observed for both samples can be attributed to alpha-helices in rhodopsin molecule, providing direct evidence of the helical structure of rhodopsin. A shoulder peak at around 34 A spacing was also observed for the dry pellet, which can be explained by the first-neighbor distance between rhodopsin molecules in the sample.

Animals↗
PubMed1996

Potentiation of the bronchoprotective effects of vasoactive intestinal peptide, isoprenaline, and theophylline against histamine challenge in anaesthetised guinea pigs by adrenomedullin.

BACKGROUND: Adrenomedullin is a hypotensive peptide recently discovered in human phaeochromocytoma which has been found to inhibit bronchoconstriction induced by histamine and acetylcholine. This study was designed to determine the manner in which adrenomedullin and other bronchodilators interact in modulating airway function. METHODS: A study was undertaken to determine whether adrenomedullin potentiated the bronchoprotective effects of isoprenaline, vasoactive intestinal peptide (VIP), and theophylline against histamine-induced bronchoconstriction in anaesthetised guinea pigs in vivo. RESULTS: Adrenomedullin in a concentration of 10(-9) M significantly inhibited histamine-induced bronchoconstriction but in a concentration of 10(-10) M it did not exhibit the bronchoprotective effect against histamine. VIP (10(-9) M) did not affect histamine-induced bronchoconstriction but it markedly inhibited the bronchoprotective effect against histamine in the presence of adrenomedullin (10(-10) M). VIP (10(-6) M) significantly inhibited histamine-induced bronchoconstriction but this effect was short lived. Adrenomedullin in a concentration of 10(-10) M potentiated bronchoprotection induced by VIP (10(-6) M) and prolonged it. Isoprenaline (10(-8) M) also significantly inhibited histamine-induced bronchoconstriction and this effect was enhanced in the presence of adrenomedullin (10(-10) M). Similarly, adrenomedullin (10(-10) M) significantly potentiated theophylline-induced bronchoprotection, and a sub-bronchoprotective dose of theophylline (20 mg/kg i.p.) was effective in preventing histamine-induced bronchoconstriction in the presence of adrenomedullin (10(-10) M). CONCLUSIONS: This study shows that adrenomedullin potentiates the bronchoprotective effects of different classes of bronchodilators against histamine challenge in anaesthetised guinea pigs.

Adrenomedullin↗
PubMed1996

Impaired pial arteriolar reactivity to hypercapnia during hyperammonemia depends on glutamine synthesis.

BACKGROUND AND PURPOSE: Acute hyperammonemia causes glutamine and water accumulation in astrocytes and loss of the cerebral blood flow response selectively to CO2. We tested whether extraparenchymal pial arterioles not subjected directly to mechanical compression by swollen astrocyte processes also lose hypercapnic reactivity and whether any such loss can be attenuated by inhibiting glutamine synthesis during hyperammonemia. METHODS: Pentobarbital-anesthetized rats were pretreated intravenously with either saline vehicle, methionine sulfoximine (0.83 mmol/kg), which inhibits glutamine synthetase and potentially gamma-glutamylcysteine synthetase, or buthionine sulfoximine (4 mmol/kg), which inhibits gamma-glutamylcysteine synthetase. Three hours after pretreatment, cohorts received an intravenous infusion of either sodium or ammonium acetate for 6 hours. Pial arteriolar diameter was measured with radiolabeled microspheres during normocapnia and 10 minutes of hypercapnia. RESULTS: With sodium acetate infusion, pial arteriolar diameter increased during hypercapnia in groups pretreated with vehicle (23+/-3% [mean+/-SE]; n=6), methionine sulfoximine (37+/-11%; n=5), and buthionine sulfoximine (32+/-3%; n=5). With ammonium acetate infusion, pial arteriolar diameter increased only in the group pretreated with methionine sulfoximine (31+/-4%; n=8) but not in those pretreated with vehicle (-2+/-4%; n=8) or buthionine sulfoximine (4+/-4%; n=6). Methionine sulfoximine, but not buthionine sulfoximine, also prevented loss of the cerebral blood flow response to hypercapnia, an increase in cortical tissue water content, and an increase in pressure under the cranial window during normocapnia in hyperammonemic rats. In contrast to hypercapnia, hypoxemia increased arteriolar diameter 30+/-7% (n=5) during ammonium acetate infusion. CONCLUSIONS: Loss of the blood flow response to hypercapnia during acute hyperammonemia is not due simply to swollen astrocyte processes passively impeding blood flow because extraparenchymal resistance arterioles also lose their reactivity selectively to hypercapnia. Lost reactivity depends on glutamine synthesis rather than on ammonium ions per se and may reflect indirect effects of astrocyte dysfunction associated with glutamine accumulation or possibly effects of glutamine on nitric oxide production.

Acetates↗
PubMed1996

Nasal absorption of 2',3'-didehydro-3'-deoxythymidine (D4T) and its esters in rats.

Nasal absorption of 2',3'-didehydro-3'-deoxythymidine (D4T) and its esters (5'-acetyl D4T: C2-D4T and 5'-hemisuccinyl D4T: Suc-D4T) was investigated in rats. Bioavailability of D4T following intranasal (i.n.) administration was 98.0%, and the elimination from plasma was as rapid as that following intravenous administration of D4T. There seemed to be complete and rapid absorption of D4T from the nasal cavity. The plasma concentration-time profile of D4T following i.n. administration of C2-D4T was almost the same as that after administration of D4T itself. This suggests that C2-D4T was rapidly absorbed from the nasal cavity, and that some amount of dosing C2-D4T was hydrolyzed to D4T before entering the systemic circulation. In contrast, Suc-D4T showed slower absorption in the i.n. administration, and the plasma D4T level was maintained for a long period.

Absorption↗
PubMed1996

Acyclothymidine alleviates intestinal toxicity of 5'-deoxy-5-fluorouridine without loss of antitumor activity in mice.

To reduce the intestinal toxicity of orally administered 5'-deoxy-5-fluorouridine (5'-DFUR) in mice, we co-administered 5'-DFUR with acyclothymidine [AcyT, 5-methyl-(2'-hydroxyethoxymethyl) uracil], a potent inhibitor of pyrimidine nucleoside phosphorylase (PyNPase). Orally administered 5'-DFUR alone caused intestinal toxicity and severe damage to the intestinal villi, while 5'-DFUR with AcyT reduced the intestinal toxicity, and prevented damage to the intestinal villi. This toxicity arising from orally administered 5'-DFUR could not be reduced by intravenous administration of AcyT, but was alleviated by oral administration. Orally co-administered AcyT showed little effect on antitumor activity of 5'-DFUR toward subcutaneously implanted Lewis lung carcinoma, though the intestinal toxicity was reduced in the tumor-bearing mice. This finding suggests that orally co-administered AcyT may prevent the undesirable conversion of 5'-DFUR to 5-FU by PyNPase during the process of absorption in the intestinal tract.

Administration, Oral↗
PubMed1996

Intestinal absorption and first-pass elimination of 2', 3'-dideoxynucleosides following oral administration in rats.

Intestinal absorption and first-pass elimination of 2',3'-dideoxynucleosides (ddNs), including 3'-azido-3'-deoxythymidine (AZT), 2',3'-dideoxyinosine (DDI) and 2',3'-didehydro-3'-deoxythymidine (D4T), following oral administration was investigated in rats. Enzymatic degradation of ddNs in rat intestinal washing and in the intestinal homogenate showed them to be stable in the washing with half lives of more than 140 h, whereas degradation of DDI in the intestinal homogenate was more than ten times as rapid as those of AZT and D4T. Intestinal absorption was studied in three segments of the rat intestine (duodenum, jejunum and colon) using an in situ closed-loop method. The area under plasma ddN concentration curve (AUC) and the residual percent of dose 1 h after dosing indicated a greater absorption of AZT and D4T in the upper intestinal tract than in the colon, very poor absorption of DDI in all segments, and considerable absorption of AZT in the colon. The AUC and the mean residence time (MRT) of ddNs following four different routes (intravenous: i.v., intra portal vein: i.p.v., intra duodenal: i.d. and intra gastric: i.g.) were measured using the in viva multiple sites of input method in rats. AZT and D4T were rapidly absorbed from the gastrointestinal tract and their bioavailability was more than 90%. DDI was less absorbed (33.02%) following i.d. administration compared with AZT and D4T. This poor absorption of DDI was partly attributable to its metabolism in the intestine.

Administration, Oral↗
PubMed1996

Modulation of the pharmacokinetics of 5'-deoxy-5-fluorouridine and 5-fluorouracil in rats by oral co-administration of acyclothymidine.

The effect of an inhibitor of pyrimidine nucleoside phosphorylase (PyNPase), acyclothymidine (AcyT), on the pharmacokinetics of 5'-deoxy-5-fluorouridine (5'-DFUR) and 5-fluorouracil (5-FU) was investigated in an oral co-administration of 5'-DFUR and AcyT in rats. AcyT increased the maximal plasma concentration (Cmax) and apparent absorption rate constant (ka) of 5'-DFUR, as expected, but the increase in AUC (area under the curve) was not significant. It was expected that AcyT would only inhibit the phosphorolytic degradation of 5'-DFUR to 5-FU, but the effect was more evident on the pharmacokinetic parameters of 5-FU than on those of 5'-DFUR. AcyT also increased AUC and Cmax of 5-FU when orally co-administered with 5-FU. An inhibitory effect of AcyT on the enzymatic degradation of 5-FU in rat liver and intestinal extract was investigated. AcyT inhibited the degradation in intestinal extract but not in the liver. The result suggests that orally administered AcyT affects the pharmacokinetics of 5-FU partly by inhibiting 5-FU degradation in the process of intestinal absorption as well as by acting as an inhibitor of PyNPase.

Administration, Oral↗
PubMed1996

Synthesis and biological activity of O-alkyl-3-N-aminoacyloxymethyl-5-fluoro-2'-deoxyuridine derivatives.

In an attempt to improve the effectiveness of action of 5-fluoro-2'-deoxyuridine (FUdR), various kinds of O-alkylated water-soluble analogues were synthesized. Antitumor activities against sarcoma 180 (solid) were also evaluated. Some compounds exhibited potent activities. In particular, 3'-O-p-chlorobenzyl-3-N-aminoacyloxy-methylester derivatives were effective over a very wide range of dose and gave extremely large therapeutic ratios compared with known 5-fluorouracil (5-FU) derivations.

Animals↗
PubMed1996

Leukopenia-inducing effect of a combination of a new 5-fluorouracil (5-FU)-derived drug, BOF-A2 (emitefur), with other 5-FU-derived drugs or BV-araU (sorivudine) in rats.

BOF-A2 (emitefur: 3-(3-[6-benzoyloxy-3-cyano-2-pyridyloxycarbonyl]benzoyl)-1-ethoxy- methyl-5- fluorouracil), a novel 5-FU (5-fluorouracil)-derived drug, was co-administered with other conventional 5-FU-derived drugs or BV-araU [sorivudine: 1-beta-D-arabinofuranosyl-(E)-5-(2-bromovinyluracil)] for 8 consecutive days to rats. BOF-A2 (6 or 8 mg/kg, p.o.) co-administered with other 5-FU-derived drugs elevated the plasma 5-FU concentration 3- to 23.3-fold and decreased the peripheral white blood cell (WBC). The percentage decreases of WBC by 5-FU (4 mg/kg, i.p.), UFT (16 mg/kg, p.o.), tegafur (FT; 16 mg/kg, p.o.), carmofur (HCFU; 15 mg/kg, p.o.), doxifluridine (5'-DFUR; 16 mg/kg, p.o.) and flucytosine (200 mg/kg, p.o.) were 25.7%, 31.9%, 70.3%, 32.0%, 58.6% and 30.0%, respectively, compared with each drug alone. On the other hand, these phenomena did not occur with BV-araU. These findings can be attributed to the fact that the inhibitory activity of CNDP (3-cyano-2,6-dihydroxypyridine) for 5-FU degradation (IC50: 6.3 x 10(-9) M) is potent and 6000 times greater than that of BVU [(E)-5-(2-bromovinyl) uracil], another inhibitor of 5-FU degradation.

Animals↗