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Biomedical subjects

Y Takeda

Publications and source records attributed to Y Takeda.

At least 667 records · Page 37Linked to original sources
PubMed1993

Suspension organ culture of the fetal mouse ear.

To observe the development of the fetal ear, we grew the explanted ears of mouse fetuses 13 days old in suspension organ culture on a roller device for 48 hours. We used the BGJb-medium (Fitton-Jackson Modification) supplemented by 25% fetal bovine serum, and added a solution containing penicillin-streptomycin at the rate of 1% to the total volume. It was observed histologically that some explants developed ossicles that corresponded with those of mouse fetuses 15 days old in vivo. Sensory structures in the inner ear developed in organ culture as well. This method may help to resolve the question of ontogenesis of the ossicles.

Animals↗
PubMed1993

Increased concentration of endothelin messenger RNA in the mesenteric arteries of cyclosporine-induced hypertensive rats.

The aim of this study was to investigate the expression of endothelin-1 (ET-1) in the mesenteric arteries of cyclosporine-induced hypertensive rats. The concentration of plasma ET-1 and of mesenteric artery ET-1 messenger RNA was measured in cyclosporine-induced hypertensive and control rats. The concentration of ET-1 messenger RNA in the mesenteric arteries of cyclosporine-treated rats (25 mg/kg/day for 6 weeks) was significantly greater than in control rats (P < .05). We propose that cyclosporine-induced hypertension may be due to an increased synthesis of ET-1 in the resistant vessels.

Animals↗
PubMed1993

Rapid acceleration of neutrophil apoptosis by tumor necrosis factor-alpha.

We demonstrate here that human necrosis factor-alpha, a potent neutrophil activator, induces rapid (within 3 h) apoptosis of these cells, i.e. neutrophils treated with this cytokine exhibit (i) light and electron microscopic changes characteristic to apoptotic cells, (ii) reduced propidium iodide binding to DNA, and (iii) the ladder form of DNA, as shown by agarose gel electrophoresis. These results suggest that apoptosis acceleration may be involved in processes by which neutrophils are prevented from damaging tissues.

Apoptosis↗
PubMed1993

Stimulation of endothelin mRNA and secretion in human endothelial cells by FK 506.

FK 506 is a powerful new immunosuppressant that is more effective in preventing and treating allograft rejection than cyclosporine (CyA). This study was undertaken to examine the effect of FK 506 on stimulation of endothelin-1 (ET-1) mRNA and secretion of ET-1 in human endothelial cells (EC) compared with the effects of CyA. The dose of 0.1 microM of CyA used in clinical practice induced expression of ET-1 mRNA and increased secretion of ET-1 in EC. The same dose of FK 506 had the same effect. A clinical dose of 0.01 microM of FK 506 did not induce expression of ET-1 mRNA and did not increase the secretion of ET-1 in EC. These findings suggest that the lower incidence of complications seen with FK 506 is due in part to its use at a lower clinical dose compared with that of CyA.

Cells, Cultured↗
PubMed1993

Age-related changes in proteoglycans of human ligamentum flavum.

Age-related changes in proteoglycans of human ligamentum flavum were studied using specimens obtained from patients divided into four age groups. The proteoglycans were purified by ion-exchange and gel-filtration chromatography. A low-molecular-weight proteoglycan with the same molecular size was present in all each age groups. Conversely, high-molecular-weight proteoglycan increased with advancing age. Properties of the sugar chains, glycosaminoglycans, in these proteoglycans were studied using cellulose acetate membrane electrophoresis and chondroitinase digestion. It was found that the high-molecular-weight proteoglycan consisted mainly of chondroitin 6-sulfate, whereas the low-molecular-weight proteoglycan consisted mainly of dermatan sulfate, although the ratio of chondroitin 6-sulfate increased with age. These results indicate that proteoglycans of human ligamentum flavum show changes in amount and composition with age.

Adolescent↗
PubMed1993

Virulence patterns of Vibrio cholerae non-O1 strains isolated from hospitalised patients with acute diarrhoea in Calcutta, India.

A collection of 28 strains of Vibrio cholerae non-O1 isolated during a 3-year period (1989-1991) from hospitalised patients with acute diarrhoea in Calcutta, India, were examined with regard to virulence-associated factors. Of the 28 isolates (each representing a case), 18 were isolated as the sole infecting agent; the remaining 10 were recovered as co-cultures from cases infected with V. cholerae O1. Of the strains isolated in this study, 82% could be serotyped, with serovars O5 (32.1%), O11 and O34 (14.3% each) predominant. Serovars O7, O14, O34, O39 and O97 were associated exclusively with sole infections. Two strains of V. cholerae non-O1 produced anti-cholera toxin IgG-absorbable cholera toxin (CT). Both CT-producing V. cholerae non-O1 strains hybridised with the DNA probe specific for the zonula occludens toxin (ZOT) but none of the remaining 26 strains hybridised with the ZOT probe. The majority of the strains were cytotoxic for CHO, HeLa and Vero cells, with end-point titres of 4-512. Fewer strains produced a cytotonic effect, with end-point titres of 2-16. Of the 28 strains of V. cholerae non-O1 examined, 75%, 75%, 25% and 14.3% produced haemolysin that was active against erythrocytes of rabbit, sheep (Eltor haemolysin), chicken and man, respectively. Strains that produced a haemolysin active against both rabbit and sheep erythrocytes were dominant (35.7%). Ten (35.7%) of the 28 strains examined showed cell-associated haemagglutinating activity on human blood. Of the 10 strains, nine were isolated as sole pathogen and only one strain was associated with mixed infection.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1993

Detection of various variant verotoxin genes in Escherichia coli by polymerase chain reaction.

We constructed common primers for the polymerase chain reaction to detect the genes for various Verotoxins reported, that is, VT1 (or SLT-I), VT2 (or SLT-II), VT2vha, VT2vhb, SLT-IIv (or VT2vp1, VTe) and SLT-IIva (or VT2vp2). A total of 80 Verocytotoxin-producing Escherichia coli strains isolated from humans, domestic animals and meats gave a positive result by PCR with the designed common primers. Digestion by restriction endonucleases BglII and EcoT14I of the amplicon of the VT2vp2 gene gave specific bands of the expected sizes, but not of the amplicons of other VT genes, suggesting a possible method for identification of the VT2vp2 gene. Application of the PCR with the designed primers in diagnostic and epidemiological studies on VTEC infection is also discussed.

Bacterial Toxins↗
PubMed1993

Identification and characterization of heat-stable enterotoxin II-producing Escherichia coli from patients with diarrhea.

Stock strains of Escherichia coli isolated from patients with traveller's diarrhea were examined for production of heat-stable enterotoxin II (STII). Of 400 strains examined, 3 were found to produce STII. The nucleotide sequence of the STII gene of these human strains was shown to be identical to that of porcine strains. Cultured cells of these strains induced fluid accumulation in ligated mouse intestinal loops and the activity was neutralized by anti-STII antiserum. These results suggest that STII-producing enterotoxigenic E. coli can cause human diarrhea.

Animals↗
PubMed1993

Characterization of mammary plaques in DDD mice congenic for Mtv-2 gene, DDD/1-Mtv-2/Mtv-2.

DDD/1 mice free from exogenous mouse mammary tumor virus (MMTV) do not develop any neoplastic mammary lesions. In GR mice, the expression of Mtv-2, an endogenous proviral MMTV, leads to 100% incidence of mammary ductal hyperplasias and tumors. An Mtv-2 congenic line, DDD/1-Mtv-2/Mtv-2, was established by introducing Mtv-2 from GR into DDD/1 to elucidate its function. Development of mammary plaques (MPQ) characterized by ductal hyperplasias was investigated in 152 congenic females on day 17 to 19 of the first pregnancy. The incidence of MPQ was 48.0% and most MPQ-positive mice (75.3%) had only one MPQ. Generally, MPQ were small in size: the diameter was as small as < or = 3 mm in 77.6% of them. Of 84 MPQ implanted into intact fat pads, 43 (51.2%), 38 (45.2%) and 3 (3.6%) showed undetectable, pregnancy-dependent and autonomous growths; respectively when the hosts underwent pregnancy. Almost all MPQ produced normal-appearing ductal-alveolar outgrowths in mammary epithelium-divested or cleared fat pads of virgins. MPQ implanted into cleared fat pads were very similar to normal mammary glands in the responses to progesterone (P) and estradiol (E) alone or in combination except for association of ductal hyperplasias in 4 of 12 MPQ under E+P treatment. These findings revealed the preneoplastic nature of MPQ. Exogenous MMTV proviruses were demonstrated in all MPQ. The int-2 DNA rearrangement was found in 2 of 10 MPQ but in none of 9 mammary carcinomas and the int-1 DNA rearrangement in none of 10 MPQ but in 5 of 10 carcinomas. It is thus likely that the Mtv-2 gene participates in a very early stage of mammary tumorigenesis not directly but indirectly through insertion mutation of host genes, while the cellular oncogenes, int-2 and int-1, may contribute to preneoplastic transformation of mammary epithelium and progression from preneoplastic to more malignant states, respectively.

Animals↗
PubMed1993

11 beta-Hydroxysteroid dehydrogenase activity in mesenteric arteries of spontaneously hypertensive rats.

1. 11 beta-Hydroxysteroid dehydrogenase (11-HSD) activity in mesenteric arteries of spontaneously hypertensive rats (SHR) and Wistar-Kyoto (WKY) rats was determined and expressed as the percentage conversion of [3H]-corticosterone to [3H]-11-dehydrocorticosterone. 2. 11-HSD activity was significantly decreased in mesenteric arteries of both 4 and 9 week old SHR (8.4 +/- 0.8%, 5.0 +/- 1.5%, respectively) compared with WKY rats (12.4 +/- 0.6%, 15.8 +/- 0.7%, respectively; P < 0.05). 3. Total RNA from rat vascular smooth muscle cells (VSMC) and endothelial cells (EC) were prepared with selective precipitation in 3 mol/L LiCl/6 mol/L urea. The expression of 11-HSD mRNA was confirmed in the rat VSMC but its mRNA expression was not detected in EC, using northern blot analysis. 4. The results in this study indicate that 11-HSD in the vascular wall may play a role in the pathogenesis of hypertension in SHR.

11-beta-Hydroxysteroid Dehydrogenases↗
PubMed1993

Effects of MS-551, a new class III antiarrhythmic drug, on action potential and membrane currents in rabbit ventricular myocytes.

1. Electrophysiological effects of MS-551, a new class III antiarrhythmic drug, were examined and compared with those of (+)-sotalol in rabbit ventricular cells. 2. In rabbit ventricular muscles stimulated at 1.0 Hz, MS-551 (0.1-10 microM) and (+)-sotalol (3-100 microM) prolonged action potential duration (APD) and effective refractory period without affecting the maximum upstroke velocity of phase 0 depolarization (Vmax). The class III effect of MS-551 was approximately 30 times more potent than that of (+)-sotalol. 3. Class III effects of MS-551 and (+)-sotalol showed reverse use-dependence, i.e., a greater prolongation of APD at a longer cycle length. 4. In rabbit isolated ventricular cells, 3 microM MS-551 and 100 microM sotalol inhibited the delayed rectifier potassium current (IK) which was activated at more positive potentials than -50 mV and saturated around +20 mV. 5. MS-551 at a higher concentration of 10 microM decreased the transient outward current (Ito) and the inward rectifier potassium current (IK1) although 100 microM sotalol failed to inhibit these currents. 6. MS-551 is a non-specific class III drug which can inhibit three voltage-gated K+ channels in rabbit ventricular cells.

Action Potentials↗
PubMed1993

Induction by endogenous noradrenaline of an alpha 1-adrenoceptor-mediated positive inotropic effect in rabbit papillary muscles.

1. The possible involvement of alpha 1-adrenoceptors in the inotropic and electrophysiological responses to endogenous noradrenaline released by tyramine was examined in rabbit papillary muscles. 2. A concentration-dependent positive inotropic effect was produced by tyramine. This effect of tyramine was not observed in muscles from rabbits pretreated with reserpine. 3. The positive inotropic effect of tyramine was greatly inhibited by propranolol, but not altered by prazosin. However, when beta-adrenoceptors were blocked by pretreatment with propranolol, tyramine still produced a positive inotropic effect, an effect which was antagonized by prazosin. 4. Tyramine caused a decrease in action potential duration (APD) and an increase in action potential amplitude in a concentration-dependent manner. Isoprenaline also produced the same electrophysiological effects. These electrophysiological effects of both agents were inhibited by propranolol. 5. When beta-adrenoceptors were blocked by propranolol, the observed prazosin-sensitive positive inotropic effect of tyramine was not accompanied by any change in APD. In contrast, APD was markedly prolonged by alpha 1-adrenoceptor stimulation with phenylephrine in the presence of propranolol, in association with the positive inotropic effect. 6. It is concluded that in rabbit papillary muscles, endogenous noradrenaline causes a positive inotropic effect predominantly mediated by beta-adrenoceptors, but can still evoke a positive inotropic effect through alpha 1-adrenoceptors when beta-adrenoceptor stimulation is eliminated. This suggests that the alpha 1-adrenoceptor-mediated positive intropic mechanism(s) may be masked by simultaneous activation of beta-adrenoceptors. In addition, this study indicates that APD prolongation is not involved in the alpha 1-adrenoceptor-mediated inotropic responses to endogenous noradrenaline.

Action Potentials↗
PubMed1993

[Incidence and prevalence of serotypes of enteroaggregative Escherichia coli from diarrheal patients in Brazil, Myanmar and Japan].

By using HeLa cells, we tried to detect enteroaggregative Escherichia coli from stock strains derived from infants with or without diarrhea in Brazil and Myanmer, and from diarrheal patients in Osaka, Japan. Enteroaggregative E. coli was detected from 7.9% in diarrheal cases, 5.6% in control cases in Brazil and from 5.4% in diarrheal cases, 3.4% in control cases in Myanmar. A total of 38 strains that showed aggregative adherence to HeLa cells was examined for colony hybridization with the 32P-labeled EAggEC probe. Thirty-four strains hybridized with the EAggEC probe, while 4 strains did not hybridize with the probe, suggesting an existence of another aggregative factor. Seventeen of the 38 strains were O-antigen serotypeable. Eight strains belonged to serogroups O44, O86, O111, O125 and O126, which have been considered to be enteropathogenic E. coli serogroups. Most of the 38 strains were H-antigen serotypeable.

Bacterial Adhesion↗
PubMed1993

[Serotypes of enteroadherent Escherichia coli exhibiting diffuse pattern of adherence isolated from diarrheal patients and healthy controls in Brazil, Myanmar and Japan].

We tried to detect enteroadherent Escherichia coli exhibiting a diffuse pattern of adherence to HeLa cells from stock strains derived from patients with or without diarrhea in Brazil, Myanmar and Japan (Osaka). Enteroadherent E. coli was found from 16 (23 strains) out of 126 (384 strains) in diarrheal infant cases (12.7%), 26 (29 strains) out of 126 (348 strains) in healthy control cases (20.6%) in Brazil, from 15 (18 strains) out of 221 (542 strains) in diarrheal infant cases (6.8%), 4 (4 strains) out of 87 (212 strains) in healthy control cases (4.6%) in Myanmar. In Japan (Osaka), enteroadherent E. coli was detected from 7 (7 strains) out of 123 (198 strains) in diarrheal cases (5.7%). These results show that enteroadherent E. coli (diffuse) may not be associated with diarrhea. Forty-four (62.9%) out of 70 strains belonged to 19 O serogroups or 21 O:H serotypes. All strains were H antigen serotypable, and 26 strains were found to be nonmotile. The predominant O:H serotypes were O11:H15, O11:H-, O20:H34, O21:H5, O89:H-, O99:H33 and O154:H45. Only one strain belonged to enteropathogenic E. coli serogroup O127.

Bacterial Adhesion↗
PubMed1993

Epitope mapping and characterization of antigenic determinants of heat-stable enterotoxin (STh) of enterotoxigenic Escherichia coli by using monoclonal antibodies.

A panel of monoclonal antibodies (MAbs) specific for the heat-stable enterotoxin (STh) of enterotoxigenic Escherichia coli was produced. All four MAbs (8G7, 53-4, 11C, and SH1) bound to native STh in an enzyme-linked immunosorbent assay to various degrees, with clone SH1 showing the best affinity. The MAbs were screened for neutralizing and guanylate cyclase-inhibiting activities by the suckling mouse assay and the cyclic GMP assay using T84 cells, respectively. The contact amino acid residues governing the reactivity of the four MAbs were precisely determined by using several chemically synthesized analogs of the various heat-stable enterotoxins (STa's). Three distinct antigenic sites of STh sufficiently removed from each other, one near the N terminus, another in the core functional region of the toxin, and the third in the C-terminal region, were recognized by the different MAbs. MAb SH1, which recognized Asn at position 4 and Tyr at position 5 from the N terminus was 100 times more potent in neutralizing the bioactivity of STh in the suckling mouse assay than was MAb 11C, which recognized Thr at position 16 and Tyr at position 19 from the N terminus of the STh molecule. The MAbs which recognized Leu at position 9 from the N terminus (MAb 53-4) and Tyr at position 19 from the N terminus (MAb 8G7) showed intermediate activities in the neutralization assay. The guanylate cyclase-inhibiting activities of SH1 and 11C essentially paralleled the results for the neutralization of bioactivity, while MAbs 53-4 and 8G7 exhibited reverse activity. These results indicate that MAbs that recognize the N-terminal residues which have been shown not to be essential for toxic activity have a potent protective capacity. None of the MAbs reacted with reduced and carboxy-methylated native STh. This suggests that all of the MAbs mediate their effect by reacting with conformation-dependent antigenic determinants.

Amino Acid Sequence↗
PubMed1993

Albumin-binding superoxide dismutase with a prolonged half-life reduces reperfusion brain injury.

To test the possible involvement of superoxide radicals in the pathogenesis of reperfusion injury, we synthesized a superoxide dismutase (SOD) derivative [poly(styrene-co-maleic acid) butyl ester (SM) covalently linked to SOD] that circulates bound to albumin, has a prolonged in vivo half-life, and accumulates in pH-decreased tissues. The protective effects of SM-SOD on regional cerebral blood flow, intracranial pressure, cardiac index, vascular permeability, and neurological outcome were investigated using a model of global brain ischemia in dogs. Intra-arterial injection of SM-SOD (10 mg/kg) just before reperfusion increased reactive hyperemia (SM-SOD, 160 +/- 36 ml.100 g-1.min-1, means +/- SD, n = 6; control, 100 +/- 34 ml.100 g-1.min-1, n = 6, P = 0.015), ameliorated delayed hypoperfusion (7 h after ischemia: SM-SOD, 40 +/- 14 ml.100 g-1.min-1; control 17 +/- 6 ml.100 g-1.min-1, P = 0.003), vascular permeability, and neurological outcome without affecting the cardiac index. These results indicate that superoxide radicals and/or their metabolite(s) might play a critical role in the pathogenesis of reperfusion injury in the brain.

Animals↗