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Biomedical subjects

T Yasuda

Publications and source records attributed to T Yasuda.

At least 775 records · Page 43Linked to original sources
PubMed1987

Application of liposomes to generation of monoclonal antibody to glycosphingolipid: production of monoclonal antibody to GgOse4Cer.

Liposomes were applied to the immunization with GgOse4Cer and screening for production of monoclonal antibody to GgOse4Cer. Four-week-old and 22-week-old Balb/c mice were immunized with GgOse4Cer and Salmonella minnesota R595 lipopolysaccharides incorporated liposomes which were composed of dipalmitoyl-phosphatidylcholine and cholesterol. Since antibody response to GgOse4Cer was higher in 22-week-old than 4-week-old Balb/c mice after immunization, 22-week-old Balb/c mice were used for the immunization prior to generation of the monoclonal antibodies to GgOse4Cer. The screening of monoclonal antibodies was performed by complement-dependent liposome immune lysis assay using GgOse4Cer-containing liposomes. Six kinds of monoclonal antibodies, AG-1, -2, -3, -4, -5, and -6, of the IgM class were established. The specificities of the monoclonal antibodies obtained were defined by complement-dependent liposome immune lysis assay using various glycosphingolipids incorporated in liposomes and by thin-layer chromatography (TLC) with immunostaining. All of the monoclonal antibodies reacted only with GgOse4Cer in the liposome immune lysis assay. In addition, the monoclonal antibodies reacted only with GgOse4Cer in the TLC immunostaining. However, none of the monoclonal antibodies obtained was capable of removing natural killer activity from C3H/He mice spleen cell suspensions in vitro. Liposomes may be useful in the procedures of immunization and screening for generation of antiserum and monoclonal antibody to GSLs.

Animals↗
PubMed1987

Tetrahymena actin: localization and possible biological roles of actin in Tetrahymena cells.

Though actin is ubiquitous in eukaryotes, its existence has not been clearly proven in Tetrahymena. Recently, we have succeeded in cloning and sequencing the Tetrahymena actin gene using a Dictyostelium actin probe (Hirono, M. et al. (1987) J. Mol. Biol. 194, 181-192). The primary structure of the Tetrahymena actin deduced from the nucleotide sequence of its gene is greatly divergent from those of other known actins, making it necessary to ascertain whether the predicted Tetrahymena actin is indeed an actin. In this paper, we investigated the localization of the predicted Tetrahymena actin by an immunofluorescence technique using antibody against its synthetic N-terminal peptide, in order to elucidate its possible biological roles. The results showed that immunofluorescence was localized in the division furrow of the dividing cell, and in the intranuclear filament bundles formed in cells exposed to heat shock or DMSO. In addition, the oral apparatus and the proximity of the cytoproct, which are organelles involved in endocytosis and exocytosis, respectively, also fluoresced. Thus, we conclude that the Tetrahymena actin we identified is indeed an actin and plays the same biological roles as ubiquitous actins do, although it is considerably divergent in its amino acid sequence.

Actins↗
PubMed1987

Left and right ventricular function after streptokinase reperfusion: assessment by gated blood pool scans.

Twenty-three patients with acute anterior or inferior myocardial infarction (AMI, IMI) were investigated by gated blood pool scans at a mean 4.9 h after reperfusion and 10 days later. Eighteen (78%) successful reperfusion cases were divided into two groups; reperfusion in less than 4 h (Rp less than 4 h, n = 9) and reperfusion in more than 4 h (Rp greater than 4 h, n = 9) from the onset of chest pain. As control group, gated blood pool scans were also performed in the early hours following infarction in an additional 42 patients who received conventional treatments. Rp less than 4 h demonstrated significant improvement of mean LVEF in AMI (from 39.5 +/- 3.3 to 50.3 +/- 3.1%, p less than 0.01) and IMI (from 54.6 +/- 4.3 to 60.4 +/- 5.8%, p less than 0.01). Improvement of initially abnormal segments was noticed in 68% of AMI and 65% of IMI by quantitative wall motion analysis, while Rp greater than 4 h showed only slight improvement of LVEF and regional wall motion compared to Rp less than 4 h. On the other hand, the control group showed no significant change in left ventricular performance and regional wall motion. In patients with AMI, RVEF remained within normal range. In IMI, whether reperfused or not, the RVEF showed moderate improvement. In conclusion, these studies indicated that the time of reperfusion and location of infarction may influence functional recovery after streptokinase reperfusion.

Adult↗
PubMed1987

Detection of intracavitary masses on gated scans: a phantom study.

A series of 1.5, 2.0 and 3.0 cm diameter paraffin balls were placed on a 3 cm tether within a simulated left ventricular balloon phantom to determine the maximal balloon volume that permitted identification of the lesion. When images were recorded with the phantom stationary, the lesions could be detected at 100, 280 and 360 ml volumes, respectively. When the phantom was set in motion with a fixed 80 ml stroke volume, the lesions were detected at 120, 320 and 360 ml, respectively. These findings suggest that gating does not decrease lesion detection even when the lesion is freely mobile, and a 1.5 cm lesion would be difficult to detect in an enlarged ventricle, but 2 and 3 cm lesions could be detected even in the presence of moderate ventricular enlargement.

Heart↗
PubMed1987

A randomized, blinded, placebo-controlled trial of recombinant human tissue-type plasminogen activator in patients with unstable angina pectoris.

Twenty-four patients with unstable angina pectoris, defined as chest pain at rest with transient ST segment deviation of at least 1 mm, were randomly assigned to blinded treatment with either placebo or intravenous recombinant human tissue-type plasminogen activator (rt-PA). Before randomization, all patients were treated with oral beta-blockers, calcium antagonists, nitrates, and continuous intravenous heparin for a monitoring period of 12 to 28 hr. After this monitoring period the 24 patients were randomly assigned to receive either placebo or 1.75 mg/kg intravenous rt-PA given over 12 hr at a rate of 0.75 mg/kg over 1 hr, 0.5 mg/kg over 4 hr, and 0.5 mg/kg over 7 hr. One patient, assigned to receive placebo, developed acute myocardial infarction after randomization but before receiving the study drug. Ischemic events were recorded during a hospital follow-up period of at least 4 days unless a further intervention was indicated or the coronary angiogram was normal. The follow-up period was 7 +/- 5 days (mean +/- SD) after the placebo infusion and 8 +/- 4 days after the infusion of rt-PA. Unstable angina pectoris persisted after the completion of the infusion in six of 11 patients receiving placebo and only one of 12 patients receiving rt-PA (p less than .03). Coronary angiography, performed 38 +/- 19 hr after the infusion, demonstrated subocclusive thrombus in eight of 11 patients receiving placebo but in none of 11 patients treated with rt-PA (p less than .002). One patient on rt-PA refused coronary angiography.(ABSTRACT TRUNCATED AT 250 WORDS)

Angina Pectoris↗
PubMed1987

Indium 111-monoclonal antimyosin antibody imaging in the diagnosis of acute myocarditis.

A definitive diagnosis of myocarditis requires right ventricular biopsy. Despite its specificity, however, right ventricular biopsy may lack sensitivity due to the focal nature of the disease. Because indium 111-monoclonal antimyosin antibody imaging can be used to detect myocardial necrosis, this procedure was performed on 28 patients clinically suspected of having myocarditis, 25 of whom had left ventricular ejection fractions of less than 45%, and the results were compared with those of right ventricular biopsy performed within 48 hr of the scan. Antimyosin scans were positive in nine patients who had evidence of myocarditis on right ventricular biopsy, and negative in 11 who had no evidence of myocarditis by biopsy. The remaining eight had positive antimyosin scans but showed no evidence of myocarditis on right ventricular biopsy. On the basis of a right ventricular biopsy standard, the sensitivity of this method was 100%, the specificity 58%. We conclude that antimyosin antibody imaging is a reliable screening method for the evaluation of patients suspected of having myocarditis, and that a positive antimyosin scan indicates the need for right ventricular biopsy to establish the histologic diagnosis.

Acute Disease↗
PubMed1987

The mechanism of action of piperacillin-analogues in vitro; effect of the carbon number at the N-4 position of 2,3-dioxopiperazine on the outer membrane permeability, stability to beta-lactamase and binding affinity to penicillin-binding proteins.

The relationship between the chemical structure and the mode of action of piperacillin-analogues (PIPC-analogues) against Escherichia coli and Klebsiella pneumoniae were investigated. The antibacterial activity of PIPC-analogues increased with an increase in the number of carbon atoms at the N-4 position of 2,3-dioxopiperazine. Their mode of action is discussed on the basis of the results of studies on outer membrane permeability, stability to beta-lactamase and binding affinity to penicillin-binding proteins (PBPs). The outer membrane permeability and stability to beta-lactamase were hardly affected by the chain length of the alkyl group at the N-4 position. On the other hand, the affinity to PBPs, especially to PBP 3, became stronger with increase of the number of carbon atoms at N-4 position. These results suggest that increased affinity to PBPs is the main reason for the increased antibacterial activity of the PIPC-analogues reported here.

Bacterial Proteins↗
PubMed1987

Myocardial damage delineated by indium-111 antimyosin Fab and technetium-99m pyrophosphate.

Technetium-99m-labeled pyrophosphate and radiolabeled antimyosin antibodies are two infarct localizing agents with apparently different kinetics of localization. To determine whether these agents localize in a similar fashion in early acute myocardial necrosis, we studied the simultaneous distribution of 111In-labeled antimyosin and 99mTc-labeled pyrophosphate in dogs after intracoronary (i.c.) (n = 9) or intravenous (i.v.) (n = 9) administration of a mixture of these two agents in a reperfused infarct model. The mean infarct size (+/- s.d.) delineated by pyrophosphate [20.2 +/- 14.1 (i.v.), 29.8 +/- 12.3 (i.c.)] was larger than that by antimyosin [14.2 +/- 11.3 (i.v.) (p = 0.05), 20.0 +/- 11.8 (i.c.) (p = 0.05)] which was larger than that by triphenyl tetrazolium chloride [13.9 +/- 8.0 (i.v.) (p = 0.05), 15.3 +/- 6.5 (i.c.) (p = 0.05)]. This overestimation persisted whether the radiopharmaceuticals were administered by intracoronary or intravenous injections, although the latter with antimyosin was only slightly larger (TTC:AM = 13.9:14.2) (p = n.s.). There was a good correlation, however, between antimyosin and pyrophosphate delineated infarct sizes in dogs with intracoronary injection (y = 0.82x + 13.33, r = 0.79) or i.v. injection (y = 1.208x + 3.01, r = 0.97) of the mixture of the two agents. Since the images of the 111In and 99mTc activities were obtained consecutively by identical methods, the overestimation of infarct size by pyrophosphate cannot be due to differences in spatial resolution of the techniques used. The differences in the areas of myocardial damage delineated by pyrophosphate and antimyosin in our study most probably denote the area of viable but compromised myocardium.

Animals↗
PubMed1987

Noninvasive detection of human cardiac transplant rejection with indium-111 antimyosin (Fab) imaging.

Diagnosis of rejection after cardiac transplantation is currently made by right ventricular endomyocardial biopsy. To evaluate antimyosin imaging as a noninvasive means of detecting human cardiac rejection, the Fab fragment of murine monoclonal antimyosin antibodies was labeled with indium-111 and given intravenously to 18 patients (age 45 +/- 12 years) in 20 studies 7 days to 9 years after transplantation. Endomyocardial biopsy specimens were obtained at the time of each imaging study. Eight patients had positive scans confirmed by biopsy as rejection, and eight patients had negative scans and no evidence of rejection on biopsy. Discordance was observed in four studies, two with positive scans and no rejection on biopsy and two with negative scans and positive biopsy. The sensitivity, specificity, and overall accuracy of the technique were each 80%. Imaging with radiolabeled antimyosin antibody Fab fragments may be of value in the noninvasive identification of rejection in the cardiac transplant recipient.

Adult↗
PubMed1987

[MTX resistant mechanisms in human choriocarcinoma cells].

Choriocarcinoma cells grown in the presence of MTX have developed resistance in two ways. The HCCM derived sublines (relatively high MTX resistant) produced enhanced levels of DHFR and had relatively unimpaired transport of MTX, though altered transport was the primary determinant of response in the CC1 derived sublines (low MTX resistant). Since the selection procedure used was identical, it was assumed that altered MTX transport was insufficient to account entirely for various degrees of resistance. Increased DHFR activity was necessary for the development of high MTX resistance. The overproduction of DHFR was the consequence of amplification of the DHFR gene sequence. The incidence of DMs in metaphases paralleled the degree of resistance. Since DMs were also present in the cells not showing DHFR gene amplification, mechanisms other than DHFR gene multiplication were responsible for the de novo synthesis of DMs.

Cells, Cultured↗