Biomedical subjects

H Tobioka

Publications and source records attributed to H Tobioka.

6 recordsLinked to original sources

PubMed1995

Cloning and characterization of cell adhesion kinase beta, a novel protein-tyrosine kinase of the focal adhesion kinase subfamily.

A second protein-tyrosine kinase (PTK) of the focal adhesion kinase (FAK) subfamily, cell adhesion kinase beta (CAK beta), was identified by cDNA cloning. The rat CAK beta is a 115.7-kDa PTK that contains N- and C-terminal domains of 418 and 330 amino acid residues besides the central kinase domain. The rat CAK beta has a homology with mouse FAK over their entire lengths except for the extreme N-terminal 88 residues and shares 45% overall sequence identity (60% identical in the catalytic domain), which indicates that CAK beta is a protein structurally related to but different from FAK. The CAK beta gene is less evenly expressed in a variety of rat organs than the FAK gene. Anti-CAK beta antibody immunoprecipitated a 113-kDa protein from rat brain, 3Y1 fibroblasts, and COS-7 cells transfected with CAK beta cDNA. The tyrosine-phosphorylated state of CAK beta was not reduced on trypsinization, nor enhanced in response to plating 3Y1 cells onto fibronectin. CAK beta localized to sites of cell-to-cell contact in COS-7 transfected with CAK beta cDNA, in which FAK was found at the bottom of the cells. Thus, CAK beta is a PTK possibly participating in the signal transduction regulated by cell-to-cell contacts.

Amino Acid Sequence↗

PubMed1994

Monoclonal antibody specifically reacting against 73-kilodalton heat shock cognate protein: possible expression on mammalian cell surface.

The heat shock proteins (hsp) are regarded as being immunogenic to the animal hosts. Although certain hsp are suggested to be expressed on the cell surface, further evidence for the cell surface expression of these proteins has been required. In this article we report the development of a MAb NT22. This antibody reacted with ATP-binding proteins (which contain a large amount of 70-kDa hsp family) of HeLa cells, and with purified bovine 70-kDa hsp. It did not react with the E. coli lysate, but clearly reacted with the recombinant rat hsc73. However, NT22 failed to react with hsp72. Furthermore, stress treatment of cells also indicated that considerable amounts of NT22-defined antigen translocated into the nucleus from the cell cytoplasm. These results suggest that NT22 is a novel MAb that reacts specifically to the mammalian hsc73. Moreover, this antibody could detect the constitutive and stress-induced cell surface expression of its relevant antigen. It is expressed preferentially on EBV-transformed B cell and certain epithelial cancer cell lines. However, resting B cells did not express this antigen on the cell surface. These data indicate that hsc73 could be expressed on the cell surface of certain cells, and suggest that hsc73 may interact with the host immune system.

Adenosine Triphosphate↗

PubMed1994

Sequential decrease in tight junctions as revealed by 7H6 tight junction-associated protein during rat hepatocarcinogenesis.

A sequential decrease in the number of hepatocyte tight junctions during the course of rat hepatocarcinogenesis was demonstrated by immunohistochemistry with a new 7H6 monoclonal antibody generated in our laboratory. Semiquantitative analysis by confocal laser scanning microscopy revealed that the expression of 7H6 antigen was reduced in hyperplastic foci, hyperplastic nodules and hepatocellular carcinomas (HCC) to 43%, 28% and 25%, respectively, compared to corresponding normal liver tissues. 7H6 antigen was scarce in HCC with a trabecular pattern, whereas it was expressed intensely at the apical and basolateral membrane of HCC with a glandular pattern. Immunoblot analysis of 7H6 expression in hepatocellular carcinomas showed a decrease roughly coincident with that shown by immunohistochemistry. These results indicated, for the first time, that tight junctions decrease progressively during carcinogenesis, leading to disruption of cellular polarity and cellular adhesiveness.

Animals↗

PubMed1985

Hexestrol residues and metabolites in the tissues of wethers injected with hexestrol dicaprylate or hexestrol.

Four young (23 kg body weight) and two mature wethers (52 and 92 kg body weight) were subcutaneously injected with hexestrol (HX) or HX dicaprylate (HX-D) and killed 41 d later. The HX residues, comprising free, glucuronide and KOH hydrolyzable forms plus metabolites were determined by gas chromatography after liquid-liquid extraction and silica gel chromatographic purification of tissue sample. The HX residues were observed to be at concentrations of .1 to 1.0 ppb in most of the tissues examined. Maturity of the animals and the two hormonal formulations resulted in little difference in residues. The KOH hydrolyzable fraction was hardly detected in the tissues examined. Free HX was a major residue in muscle, representing about 70% of HX residues. Glucuronide HX represented 70 to 80% of HX residues in liver and kidney. In lung, glucuronide and free HX were present in similar amounts. This study showed that the gross metabolic patterns of HX and its esters are similar to other estrogens and steroids.

Animals↗

PubMed1981

Gas-liquid chromatographic determination of hexestrol residues in adipose tissue.

A gas-liquid chromatographic (GLC) method is described for determining hexestrol residues in adipose tissue. The extraction and purification procedures were based on a published method for determining diethylstilbestrol. To increase precision and sensitivity, the sample was further cleaned up by silica gel column chromatography. The heptafluorobutyric (HFB) derivative of hexestrol was used for GLC analysis with HFB-docosanol as an internal standard. A variety of acetone-benzene mixtures were compared to determine the optimum ratio for hexestrol acylation. Acetone-benzene (90 + 10) or 100% acetone provided 16% higher GLC response than did a 50 + 50 mixture (P less than 0.001) and was selected for use in the acylation procedure. A system for evaporating excess reagents was also studied. Overall percent recovery reached 72 +/- 5. The method can be used to determine residual hexestrol at the 0.1 ppb level.

Acylation↗

PubMed1978

Modified method for electron capture gas-liquid chromatographic determination of hexestrol residues in bovine tissues.

A gas-liquid chromatographic (GLC) method with electron capture detection was developed for determining hexestrol residues based on a GLC method for diethylstilbestrol residues. The extraction and purification procedures were based on a published procedure. Pentafluoropropionic (PFP) and heptafluorobutyric (HFB) anhydrides and other halogenated compounds were compared as acylation reagents. PFP anhydride was selected because it provided reproducible GLC responses. Of the 3 column packing materials tested, OV-17, OV-210, and QF-1, OV-17 was the most stable under the GLC conditions used. A pH 10.5--10.6 in the purification step gave higher recoveries than pH 10.3 or pH 10.8 and was selected for use. The method is suitable for determining residues of 0.5 ppb. The limit of sensitivity ranges from 0.1 to 0.2 ppb.

Animals↗