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Biomedical subjects

T Hirata

Publications and source records attributed to T Hirata.

At least 451 records · Page 25Linked to original sources
PubMed1985

Effects of 5-acetylspiro[benzofuran-2(3H),1'-cyclopropan]-3-one, a new anti-ulcer agent, on experimental acute and chronic ulcers.

The effects of 5-acetylspiro[benzofuran-2(3H),1'-cyclopropan]-3-one (AG 629), a newly synthesized compound, on various experimentally induced ulcers were investigated. Oral or intraduodenal administration of AG 629 in a dose range of 25-100 mg/kg inhibited water-immersion stress ulcer, exertion ulcer, Shay ulcer, indometacin- and acetylsalicylic acid (ASA)-induced gastric ulcer, and indomethacin-induced small intestinal ulcer in rats, histamine-induced gastric ulcer in guinea pigs, and ASA-induced gastric ulcer in dogs, though it was not effective against cysteamine-induced duodenal ulcer in rats. AG 629 in doses of 6.3-25 mg/kg p.o. twice a day significantly promoted the healing of acetic acid- or thermal-cortisone-induced gastric ulcers and acetic acid-induced duodenal ulcers in rats. AG 629 (25-100 mg/kg i.d.) inhibited the secretion of gastric acid and pepsin in pylorus-ligated rats and the acid secretion stimulated by distension of the rat stomach with air, whereas this compound did not affect acid secretion stimulated by histamine, pentagastrin, carbachol or 2-deoxy-D-glucose. This study shows that AG 629 has both prophylactic and curative effects on various ulcers. The anti-ulcer effect of this agent seems to be mediated primarily by increasing mucosal resistance and secondarily by an antisecretory activity.

Acetates↗
PubMed1984

Diagnosis of tricuspid stenosis by M-mode and two-dimensional echocardiography.

A decreased diastolic slope (EF slope) of the tricuspid valve on the M-mode echocardiogram may not indicate the presence of tricuspid stenosis (TS). To explore diagnostic echocardiographic signs of TS, we examined an M-mode and 2-dimensional (2-D) echocardiogram in 9 patients with documented TS of rheumatic origin and in 14 patients with rheumatic heart disease who showed a decreased EF slope (less than 40 mm/s) but did not have TS. By M-mode echocardiography, the EF slope was not different between patients with TS (24.4 +/- 2.2 mm/s) and those without TS (27.4 +/- 2.0 mm/s). The early diastolic excursion (DE amplitude) of the tricuspid valve was significantly lower (p less than 0.001) in patients with TS (7.6 +/- 1.0 mm) than in patients without TS (13.9 +/- 0.6 mm). Two-dimensional echocardiograms of the tricuspid valve revealed diastolic doming in all patients with TS. Diastolic doming of the tricuspid valve was detected most often (all of 7 patients) in the apical 4-chamber view. In contrast, no patients without TS who had a decreased EF slope on the M-mode echocardiogram showed diastolic doming. These data suggest that a reduced DE amplitude of less than or equal to 10 mm associated with a decreased EF slope on the M-mode echocardiogram and diastolic doming of the tricuspid valve on the 2-D echocardiogram are useful echocardiographic signs in the diagnosis of TS.

Adult↗
PubMed1984

F1ATPase of Escherichia coli: a mutation (uncA401) located in the middle of the alpha subunit affects the conformation essential for F1 activity.

F1ATPase from the Escherichia coli mutant of H+-ATPase, AN120 (uncA401), has less than 1% of the wild type activity and has been shown to be defective in the alpha subunit by in vitro reconstitution experiments. In the present study, the mutation site was located within a domain of the subunit by recombinant DNA technology. For this, a series of recombinant plasmids carrying various portions of the alpha subunit gene were constructed and used for genetic recombination with AN120. Analysis of the recombinants indicated that the mutation site could be located between amino acid residues 370 and 387. The biochemical properties of the mutant F1 were analyzed further using the fluorescent ATP analog DNS-ATP (2'-(5-dimethylaminonaphthalene-1-sulfonyl)-amino-2'-deoxy ATP). The single turnover process of E. coli F1ATPase proposed by Matsuoka et al. [(1982) J. Biochem. 92, 1383-1398.] was compared in the mutant and wild type F1's. Mutant F1 bound DNS-ATP and hydrolyzed it as efficiently as wild type F1. Results showed that binding of ATP to a low affinity site, possibly in the beta subunit, caused decrease of fluorescence of DNS-ATP in the wild type F1 and that this effect of ATP binding was inhibited by DCCD (dicyclohexyl carbodiimide). However, this effect was not inhibited by DCCD in the mutant F1, suggesting that in the proposed process some step(s) after ATP binding to the low affinity site differed in the mutant and wild F1's. When Pi was added to F1 bound to DNS-ATP or to aurovertin, a fluorescent probe capable of binding to the beta subunit, the opposite changes of fluorescence of these probes in the mutant and wild type F1's were observed, suggesting that the conformational change induced by phosphate binding was altered in the mutant F1. On the basis of the estimated mutation site and the biochemical properties of the mutant F1, the correlation of the domain of this site in the alpha subunit with the function of F1 ATPase is discussed.

Adenosine Triphosphate↗
PubMed1984

Evaluation of a system for on-line analysis of VO2 and VCO2 for clinical applicability.

The authors evaluated the accuracy of a system to measure respiratory gas exchange on an on-line basis by comparing it with a gas collection method. The system incorporates a hot-wire flowmeter, a mass spectrometer, and a microcomputer. It performs on-line compensation for both transport delay and dynamic response of the mass spectrometer. Compensation of flow measurement for changing gas fractions also is performed. Excellent linear correlations were obtained between the two methods: 1) in animals during mechanical ventilation with room air (VO2:r = 0.995; VCO2:r = 0.993), and nitrous oxide in oxygen (VO2:r = 0.975; VCO2:r = 0.976); and 2) in men spontaneously breathing room air at different workloads (VO2:r = 0.999; VCO2:r = 0.998), and higher inspired oxygen fractions (FIO2 0.38 to 0.75) (VO2:r = 0.910; VCO2:r = 0.988). The authors consider that the system is suited for accurate and continuous measurement of respiratory gas exchange during mechanical ventilation, anesthesia, and exercise testing.

Adult↗
PubMed1984

Novel carbapenem derivative SF2103A: studies on the mode of beta-lactamase inactivation.

A novel carbapenem, SF2103A, is a strong inhibitor of various types of beta-lactamase. Equimolar concentrations of SF2103A completely inactivated the cephalosporinases of Proteus vulgaris and Citrobacter freundii and type Ib and type II penicillinases mediated by R plasmids in a progressive manner. The inactivation of the two penicillinases and P. vulgaris cephalosporinase was apparently irreversible; however, when the inactivated enzymes were separated from excess SF2103A by gel filtration, they showed very slow reactivation. The hydrolysis of SF2103A by these three beta-lactamases was below the limit of detection. It is concluded that SF2103A acts as a tight-binding competitive inhibitor for the penicillinases and P. vulgaris cephalosporinase. In contrast, the inactivation of C. freundii cephalosporinase by SF2103A was evidently reversible. The rate constant of reactivation of the enzyme was compatible with the turnover rate of the enzyme in the steady state of SF2103A hydrolysis. Thus, SF2103A simply acts as a poor substrate for C. freundii cephalosporinase.

Anti-Bacterial Agents↗
PubMed1984

[Abdominal ultrasonography in infants and children].

Ultrasonography is very useful and suitable for evaluating abdominal masses especially in infants and children, because it is a noninvasive, painless method and does not utilize ionizing radiation. Since 1962 we have examined various abdominal diseases in the pediatric field using ultrasonic machines with A-mode, bistable and gray scale contact compound scanners. Currently, it has become much easier to find very small lesions in the abdomen with a real time B-scanner. Hepatocarcinoma, choledochal cyst, neuroblastoma, ovarian teratoma, Wilm's tumor and hydronephroureter were presented and their echographic features were discussed. Pediatric abdominal ultrasonography is a very important modality for making accurate and quick decisions in the treatment of diseased infants and children.

Abdominal Neoplasms↗
PubMed1984

[A study on tumor marker of tissue-polypeptide-antigen (TPA) in gynecologic malignancies].

Tissue polypeptide-antigen (TPA), a tumor-associated antigen reported by Bjorklund et al., is a single chain polypeptide of approximately 22,000-45,000 molecular weight, which is being studied in various fields as a tumor marker. We determined the serum TPA level and tissue distribution of TPA in patients with gynecologic malignancies and healthy women. In healthy women, the serum TPA level was under 110 mu/l, without any relation to age or sex. In benign tumors, the mean serum TPA was 123.9 mu/l and it is comparable with that in healthy women. In cervical cancers, it was 212 mu/l and significantly higher than those in healthy women and in patients with benign tumors (p less than 0.01). In ovarian cancers, it was 414.7 mu/l, which showed significantly higher levels of serum TPA in ovarian cancers than those in healthy women and in patients with benign tumor, and it was also significantly higher than that in cervical cancers (p less than 0.001). As for the values after treatment, the serum TPA level clearly tended to fall in patients exhibiting good response, and tended to rise in those showing poor response. TPA was markedly localized in the cancer cells, but was almost entirely absent from the normal tissues of the cervix and endometrium.

Adenocarcinoma, Mucinous↗
PubMed1984

[Postoperative treatment for malignant intracranial tumors--especially concerning intermittent intra-carotid administration of adriamycin].

Seventeen patients, aged 9 to 63 years (mean age 38.2 years), with 6 recurring malignant glioma, 5 malignant meningioma, 4 metastatic brain tumor, one endodermal sinus tumor and one embryonal carcinoma were postoperatively treated with adriamycin (ADM). As a rule, 20 mg of ADM (to 960 mg in a total dosis) were given by means of intra-carotid administration every two weeks (to 250 months in duration). According to Karnofsky's evaluation, 4 of 6 glioblastoma patients(66.7%), 4 of 5 malignant meningioma (80%), 2 of 4 metastatic brain tumor (50%) and one embryonal carcinoma had improvement of clinical condition, at least during two months after the beginning of the treatment, and/or remission of more than 50% of the enhanced area on CT scan. Consequently, allover response rate was 64.7%. Tumor tissue concentration of ADM administered intraoperatively by the same regimen, was estimated by fluorescence assay, twenty times in sixteen patients. The level of the concentration was higher in malignant tumor (3.6 to 6.2 micrograms/g) than in low grade astrocytoma (1.5 microgram/g in maximum) during sixty minutes after ADM administration. On the other hand, when ADM of same dosis was given intravenously, maximum serum level was 2.8 microgram/ml, which was less than half in comparison with tissue level of intracarotid administration. There was a serious myelosuppression in two cases in our series, but no cardiomuscular damage was observed in any cases. In conclusion, ADM concentration of brain tissue such as malignant meningioma, metastatic brain tumor and, even glioblastoma, was highly obtained. Further, intermittent intra-carotid administration of ADM was more effective than intravenous dripping in treating malignant intracranial tumor, although side effects should be carefully avoided.

Adolescent↗