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Biomedical subjects

T Akatsuka

Publications and source records attributed to T Akatsuka.

At least 55 records · Page 3Linked to original sources
PubMed1990

Monoclonal antibodies to the amino-terminal sequence of the c-yes gene product as specific probes of its expression.

An amino terminal sequence of 64 amino acid residues specific to human c-yes was expressed in E. coli as a fused molecule with a bacterial phosphate binding protein. The fused protein was used as both immunogen for mice and antigen to obtain monoclonal antibodies against the c-yes protein. Monoclonal antibodies (MAbs) from two monoclonal hybridomas (1B7: IgG2a, 3H9: IgG1) recognized human p62c-yes in blotting analyses. In addition, MAb3H9 reacted with murine p62c-yes. The p62c-yes immunoprecipitated with Mab1B7 exhibited protein tyrosine kinase and autophosphorylation activities in vitro. Immunohistochemical analysis with MAb1B7 showed that the p62c-yes expression in the kidney was confined to the proximal tubules.

Adult↗
PubMed1989

Biochemical and immunological characterization of murine leukemia viruses that are paralysis-inducing in rats.

The molecular size and pI of the viral structural proteins of four PVC viruses (PVC111, PVC211, PVC321 and PVC441) were compared by single or two-dimensional polyacrylamide gel electrophoresis. PVC111 had slightly larger p15E and gPr85 molecules (about 0.5 kilodalton) than did the other PVC viruses. On the other hand, the virion structural proteins p30, p15, p12E and p12 from all the viruses had the same molecular sizes and pIs. The gp70s and p10s from all the viruses showed the same molecular sizes. A monoclonal antibody to gp70 of PVC321 virus recognized the gp70s of all PVC viruses, but not the gp70s of four clones of the wild mouse ecotropic viruses, Friend murine leukemia viruses (F-MuLV), AKR ecotropic MuLV, dual-tropic F-MuLV or NZB endogenous xenotropic MuLV, revealing that these four PVC viruses are homologous with each other, but distinct from the known mouse retroviruses.

Animals↗
PubMed1989

Evaluation of myocardial perfusion abnormality by profile analysis for digital subtraction angiogram.

For quantitative estimation of ischemia, ECG-synchronized digital subtraction angiography was performed for selective coronary arteriography. The authors obtained sequential myocardial perfusion images at the arterial, capillary, and venous phases. Profile densitometry was performed along the cross section perpendicular to the long axis of the left ventricle to assess regional myocardial perfusion at the capillary phase quantitatively. By this densitometry, the volumes of vascular bed perfused by the left coronary artery could be estimated, and further, nontransmural myocardial infarction could be differentiated from transmural myocardial infarction through the profile of its density curve. This method appears to be useful for the analysis of myocardial perfusion of ischemic heart disease.

Adult↗
PubMed1989

[Quantitative evaluations of left ventricular function obtained by electrocardiographically-gated magnetic resonance imaging].

Using electrocardiographically-gated magnetic resonance imaging, regional cardiac function was evaluated in 12 normal volunteers and in 10 cases of old myocardial infarction. The optimal short axis of the left ventricle was selected at the chordae tendineae level. The left ventricle was divided into 12 segments using a computer-aided system, and percentile shortening fraction (%SF) and percentile wall thickening (%WT) were calculated in each segment by the fixed coordinate method. In the normal volunteers, heterogeneity of both %FS and %WT was observed, ranging from 25 +/- 13% and 37 +/- 13%, respectively in the septal segment, to 49 +/- 13% and 60 +/- 21%, respectively in the posterior segment. In the cases of myocardial infarction, decreased %FS and %WT were detected at the affected regions. The abnormal regions revealed by %WT tended to be narrower than those revealed by %FS. Thus the MR technique at the optimal axis may be useful for quantitative evaluations of regional cardiac function.

Adult↗
PubMed1988

Characterization of hepatitis B virus X gene: in vitro translation of mRNA from COS-1 cells transfected with the X gene.

To elucidate the biological role of the X region of HBV DNA, we constructed an expression plasmid pSV2HBx by inserting the StuI/BglII fragment of HBV DNA into the pSV2 vector. Although X region products were not identified in vivo in transfected COS-1 cells, transcripts were translated in vitro and a 17-k Da protein was immunoprecipitated with an antibody raised against a synthetic peptide corresponding to the carboxy terminus of the X region open reading frame. Among 68 HBV carrier sera tested, two were found to contain antibodies reactive to the in vitro translation product. These results suggest that the X region is a gene which can be actually expressed at some stage of HBV infection.

Animals↗
PubMed1988

Stable expression of the hepatitis B virus surface antigen containing pre-S2 protein in mouse cells using a bovine papillomavirus vector.

The large BglII fragment (2.8 kilobases) of hepatitis B virus DNA including the transcription unit for the hepatitis B surface antigen (HBsAg) was inserted into a bovine papillomavirus vector containing the neomycin resistance gene. The recombinant DNA was transfected into mouse C127 cells. A stable transformed cell line (MS128) secreting a large amount of 22 nm HBsAg particles containing pre-S2 protein was established. The secreted HBsAg particles had the receptor for polymerized human serum albumin. Immunoprecipitation and Western blot analyses showed that HBsAg particles consisted of two major proteins of 22K and 26K encoded by the S gene and a minor protein of 35K encoded by the pre-S2 and S genes. Southern blot analysis revealed that the transfected plasmid was integrated into the host chromosomal DNA and that most of the plasmid sequences were present. These results suggest that the stable expression of the HBsAg in MS128 cells is related to the integrated state of the recombinant DNA.

Animals↗
PubMed1987

Fetal heart variability indices and the accuracy of variability measurements.

Several indices of fetal heart rate variability, including short-term variability (STV) and long-term variability (LTV) were analyzed. All the STV indices studied were found to be almost identical statistically. The LTV indices of de Haan et al were the same in essence, while other LTV indices reflected only the fluctuation around the mean fetal heart rate. Analysis using a signal generator indicates that the value of the standard deviation of beat-to-beat difference (one STV index) of less than 7 msec, through the cardiotocomonitor is unreliable; if the standard deviation of beat-to-beat difference is to be measured with an accuracy of 1 msec, an accuracy of measurement of 0.11 msec is necessary even if the fetal heart beat data are sampled with a sampling interval of 1 msec.

Female↗
PubMed1986

A monoclonal anti-double stranded DNA antibody from an autoimmune MRL/Mp-lpr/lpr mouse: specificity and idiotype in serum immunoglobulins.

Anti-double stranded (ds) DNA antibodies in the sera of lupus-prone MRL/Mp-lpr/lpr (MRL/l) mice were determined by an enzyme-linked immunosorbent assay in parallel with anti-single stranded (ss) DNA, anti-left-handed Z-DNA and anti-poly(ADP-ribose) antibodies. The serum levels of these antibodies in these mice increased with age, and in particular anti-dsDNA antibodies appeared in mice more than 14 weeks old, along with progressive lymphadenopathy. We therefore established a hybridoma producing monoclonal anti-dsDNA antibody (2C10) from an 8-month-old MRL/l mouse. Monoclonal antibody 2C10 did not react with either poly(dT) or poly(I), which are major cross-reactants with previously reported monoclonal MRL mouse autoantibodies. Antibody 2C10 showed preference for phi X-174 replicative form DNA and calf thymus dsDNA over ssDNA. 2C10 idiotype (Id) was present in the sera of MRL/l mice, but only occasionally at high levels even in the aged mice tested. This result suggested that many Ids with anti-dsDNA antibody activity may contribute to lupus pathogenesis in this strain of mouse.

Aging↗
PubMed1986

Detection of an antigen (AN6520), possibly related to non-A, non-B hepatitis, by monoclonal antibodies. I.

The antibody to AN6520 antigen, which was isolated from the liver of a patient with non-A, non-B hepatitis (NANBH), has been detected frequently in convalescent sera from patients with NANBH by the passive hemagglutination (PHA) test. In a further study, we established hybridoma cells secreting antibodies against AN6520 antigen and obtained ascitic fluids with PHA titers ranging from 1:10(5) to 1:10(7). In immunodiffusion with AN6520 antigen, all monoclonal antibodies were found to form an identical precipitin line. These lines were also identical to those formed by rabbit antiserum against AN6520 antigen and by convalescent sera from patients with NANBH. With one of the monoclonal antibodies, 1-F12, solid-phase radioimmunoassay (SP-RIA) for detecting AN6520 antigen was developed as well as blocking RIA for anti-AN6520 antibody detection. The antigen assay was 50 times more sensitive than the reverse passive hemagglutination (R-PHA) test, with a sensitivity threshold of the 1 ng/ml of antigen solution; the antibody assay was 10 times more sensitive than PHA. The results with this blocking RIA were mostly in agreement with the data obtained by PHA. Furthermore, the antigen in human sera, which had never been detected by R-PHA test, could be detected by SP-RIA.

Aged↗
PubMed1986

Non-A, non-B hepatitis related AN6520 Ag is a normal cellular protein mainly expressed in liver. II.

Detection of AN6520 Ag/Ab in human sera had indicated a close association with non-A, non-B hepatitis (NANBH). In this study, we investigated the immunochemical nature of AN6520 Ag and measured the amounts in various human and chimpanzee organs in order to clarify the association with NANBH. AN6520 Ag was found to be composed of polypeptide(s) with an apparent molecular weight of 45,000 daltons (45 kD), which are noncovalently linked together. Human antibodies in convalescent sera from NANBH patients as well as monoclonal antibodies were found to recognize only the high-order structure of the antigen, whereas rabbit antibody recognized both the high-order structure and the reduced form of 45 kD polypeptide(s). AN6520 Ag could be detected in most of the livers tested including those without any liver damage and fetal livers; their amounts varied considerably from each other. The antigen could be detected also in organs other than liver, but in contrast to liver, the amounts were small and did not vary as much between individuals. From the data of immunoblotting using rabbit antibody, our observed variation of antigen content in liver was considered to be due to the difference in expression of 45 kD polypeptide(s). Although no specific relationship was found between the amount of the antigen in liver and NANBH, the antigen was found to increase several times in livers of chimpanzees after the inoculation of NANBH virus. These data suggest that AN6520 Ag is a normal cellular protein existing mainly in liver and that its quantity may vary under some conditions such as NANBH.

Adult↗
PubMed1986

An experimental study for analyzing nerve conduction velocity.

Conduction velocities of so called A fibers in the bullfrog's sciatic-peroneal nerve were studied by means of a collision neurography in which a submaximal shock to the distal part of the nerve was used to block descending impulses from a supramaximal shock delivered to the proximal two parts of the same nerve respectively. The onset latency of the response to stimulation delivered to the proximal part was almost unchangeable within a certain range of the stimulus intensity of the distal part and fell into 3 classes, and then conduction velocities of so called A fibers were divided into 3 groups. These findings were in good agreement with those obtained by Erlanger and Gasser (1937) using monophasic recording. On the other hand, the distribution of the external diameter of myelinated nerve fibers examined was unimodal. It may depend on the change in threshold due to stimulation through fluid electrodes that the onset latency of the response of a nerve trunk was divided into 3 classes.

Animals↗
PubMed1986

Clinical validity of washout time constant images obtained by digital subtraction angiography.

Functional images of left ventricular myocardial perfusion were obtained using the washout time constant obtained from the analysis of digital subtraction angiograms (DSA). The results were compared with those of left ventriculography to evaluate its clinical validity. DSA examinations were performed in eight patients with old anterior myocardial infarction and in 10 control subjects. Washout time constant images of the left ventricular wall were nearly homogeneous in normal cases. On the contrary, regional heterogeneity on the washout time constant images was observed in cases of anterior infarction. The abnormal region in the washout time constant image corresponded well to the area of abnormal percent wall thickening, whereas the extent of the abnormal wall motion area tended to be broader than that of the abnormal washout time constant area or area of abnormal percent wall thickening. Thus, the washout time constant images obtained by DSA may comprise a reliable means of estimating the extent of ischemia in the myocardium.

Aged↗
PubMed1986

Digital subtraction angiography: image-sequence analysis for regional myocardial perfusion dynamics.

Digital subtraction angiography with selective coronary injections of contrast media has enabled us to obtain clear images, not only of the artery, but of the capillary and venous phases of the myocardial perfusion. In the present study, densitometry was used to estimate regional myocardial perfusion dynamics in 10 control cases and 11 anterior myocardial infarction cases. The time density curve showed that contrast material increased rapidly in the arterial phase and appeared to be washed out monoexponentially in the venous phase. The time from the onset of contrast medium injection to the maximal density of the contrast medium (Tp), and the time constant obtained from the washout curve (Tc) were analyzed. In the control group, Tp in the apical region was slightly prolonged as compared with Tp in the anterobasal region, but the difference was not significant (5.2 +/- 0.5 vs 4.2 +/- 0.4 sec: mean +/- SEM). Tc did not definitely change in any portion of the myocardium (anterobasal 5.1 +/- 0.5, anterior 4.8 +/- 0.5, apex 4.6 +/- 0.5 sec, respectively). In anterior myocardial infarction, Tp in the marginal region was significantly prolonged compared to Tp in the control region (6.0 +/- 0.3 vs 4.7 +/- 0.3 sec, p less than 0.01). Tp was prolonged for more than 10 sec in the infarcted region. Tc in the marginal region was markedly prolonged compared to Tc in the control region (7.4 +/- 0.9 vs 4.4 +/- 0.5 sec, p less than 0.025). Tc could not be determined in the infarcted regions because data acquisition time of our apparatus was inadequate.(ABSTRACT TRUNCATED AT 250 WORDS)

Coronary Angiography↗
PubMed1985

Transmission of human T-cell leukemia virus type I to an S+L- cat kidney cell line.

The S+L- cat kidney cell line CCC was cocultivated with lethally irradiated human lymphoid cell lines that were producing human T-cell leukemia virus type I (HTLV-I). Eight of nine S+L- CCC sublines that had been cocultivated with nine different HTLV-producing T-cell lines gave positive reactions for HTLV antigens by indirect immunofluorescence assay. One subline CCC/2M was cloned. The percentages of fluorescent cells differed markedly in different sublines and clones. Southern blot hybridization with HTLV probes and electrophoresis of immunoprecipitates indicated that defective HTLVs were often transmitted into S+L- cat cells. S+L- CCC cells were permissive for HTLV and the properties of HTLV-infected cat cells were heterogeneous.

Animals↗