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S Taga

Publications and source records attributed to S Taga.

At least 37 records · Page 2Linked to original sources
PubMed1995

The fate of human CD77+ germinal center B lymphocytes after rescue from apoptosis.

Germinal center (GC) B lymphocytes, defined by various criteria, have been shown to spontaneously undergo apoptosis in vitro unless they receive a positive signal. This rescue signal seems to be a multi-component process which involves not only the B cell receptor but also other cell surface receptors such as the CD40 antigen. In previous studies, we have shown that expression of the CD77 antigen is restricted to GC B lymphocytes and that CD77+ cells readily enter programmed cell death when cultured in vitro. In order to better characterize the CD77+ B lymphocytes, we have investigated the fate of these cells after rescue from apoptosis. Survival of CD77+ cells was achieved either with a combination of anti-CD40 mAb and IL4 (the CD40 system developed by Banchereau et al., (1991) Science 251, 70-72) or EBV infection. After 4 days of culture, similar phenotypic and functional changes of the CD77+ lymphocytes were observed in both systems: CD77 antigen was down-regulated, CD23 antigen which was originally negative became strongly expressed and the expression of CD38 and CD20 remained constant. Furthermore, large quantities of soluble CD23 were produced by the surviving cells. These results indicate that CD77 antigen is expressed by GC B cells which are highly susceptible to enter apoptosis but which are not doomed to die.

Antibodies, Monoclonal↗
PubMed1994

Positive and negative transcriptional regulation by the yeast GAL11 protein depends on the structure of the promoter and a combination of cis elements.

GAL11 was first identified as a gene required for full expression of some galactose-inducible genes that are activated by GAL4, and it was subsequently shown to be necessary for full expression of another set of genes activated by RAP1/GRF1/TUF. Genetic analysis suggests that GAL11 functions as a coactivator, mediating the interaction of sequence-specific activators with basal transcription factors. To test this hypothesis, we first tried to identify functional domains by deletion analysis and found that the 866-910 region is indispensable for function. Using reporters bearing various upstream activating sequences (UAS) and different core promoter structures, we show that the involvement of GAL11 in transcriptional activation varies with the target promoter and the particular combination of cis elements. Gel electrophoresis in the presence of chloroquine shows that GAL11 affects the chromatin structure of a circular plasmid. Based on these findings, the role of GAL11 in regulation of transcription, including an alteration in chromatin structure, is discussed.

Amino Acid Sequence↗
PubMed1994

A clinicopathological evaluation of nucleolar organizer region proteins in human breast carcinoma.

The number of nucleolar organizer region proteins (NORs) identified by silver staining (Ag) was studied in 106 primary breast carcinomas. The AgNOR score (mean +/- SD) in tumours smaller than 2 cm was significantly lower than that in tumours larger than 2 cm (P < 0.05). However, there was no significant difference according to other clinicopathological characteristics. According to postoperative distant recurrence, the AgNOR count was significantly higher in the group with recurrence than in the group without recurrence (P < 0.05). Further, the survival rate was significantly lower in the high AgNOR score (> or = 3) group than in the low score (< 3) group (P < 0.01). The present study indicates that the AgNOR score in human breast cancer cells is useful for evaluating cell proliferative activity and may help predict postoperative distant recurrence and, ultimately, the postoperative prognosis of patients.

Adult↗
PubMed1993

Apoptosis induced in Burkitt's lymphoma cells via Gb3/CD77, a glycolipid antigen.

Gb3/CD77 is a glycolipid antigen, specifically expressed on two different B-cell populations, Burkitt's lymphoma and a subset of tonsillar B-lymphocytes located in germinal centers, which could be the normal counterpart of Burkitt cells. Both Gb3/CD77(+) populations have recently been shown to enter programmed cell death (apoptosis) readily. Here we show that verotoxin, also called Shiga-like toxin, which is known to bind to the carbohydrate moiety of Gb3/CD77, induces cell death in Gb3/CD77(+) Burkitt's lymphoma cells, not only by inhibiting protein synthesis as classically described but also through an additional mechanism, namely apoptosis. Furthermore a recombinant B-subunit of verotoxin, which carries only the binding property of the holotoxin, also induces apoptosis in Gb3/CD77(+) cells. Gb3/CD77 could thus represent the first example of a glycolipid antigen able to transduce a signal leading to apoptosis.

Antigens, CD↗
PubMed1990

Distribution and cyclic change of aromatase cytochrome P-450 activity in human uteri.

Activities of aromatase cytochrome P-450 in the columnar epithelial region (CE), squamous epithelial region (SE) and connective tissue (CT) of uterine cervix, and endometrium (EM) during the menstrual cycle were determined using [4-14C] and [1 beta-3H]androstenedione. Aromatase activities in the proliferative phase (n = 8) were 15.0 +/- 7.9, 10.9 +/- 10.3, 9.4 +/- 10.6 and 8.0 +/- 7.3 (mean +/- SD) fmol/h/mg protein in CE, SE, CT and EM, respectively, and aromatase activities in the secretory phase (n = 6) were 31.5 +/- 7.6, 19.1 +/- 7.1, 5.6 +/- 4.6 and 6.3 +/- 1.5 fmol/h/mg protein, respectively. The results show that the aromatase activities in these regions in the proliferative phase were not significantly different from each other. On the other hand, the aromatase activity in the secretory phase was significantly higher in CE than in any other regions (P less than 0.05), and significantly higher in SE than in CT or EM (P less than 0.05). There was no significant difference in aromatase activity between CT and EM. By comparison of aromatase activity between these two phases, the activity in CE was significantly higher in the secretory phase than in the proliferative phase (P less than 0.05), but no significant difference was observed in other regions.

Adult↗
PubMed1986

Adecypenol, a unique adenosine deaminase inhibitor containing homopurine and cyclopentene rings. Taxonomy, production and enzyme inhibition.

Adecypenol, which exhibits potent inhibitory activity against calf intestinal adenosine deaminase (EC 3.5.4.4), was isolated from the cultured broth of Streptomyces sp. OM-3223. Adecypenol was classified as a semi-tight binding inhibitor. The Ki value against calf intestinal adenosine deaminase was 4.7 X 10(-9) M. No acute toxicity of adecypenol was observed at 100 mg/kg in mice. Adecypenol exhibited no antimicrobial activity against various bacteria and fungi at the concentration of 1.0 mg/ml.

Adenosine Deaminase Inhibitors↗
PubMed1982

Molecular heterogeneity of heat-labile enterotoxins from human and porcine enterotoxigenic Escherichia coli.

The heat-labile enterotoxins produced by human enterotoxigenic Escherichia coli (LTh) and porcine enterotoxigenic E. coli (LTp) were purified to homogeneity, and their molecular properties were compared with those of purified cholera enterotoxin (CT). On polyacrylamide gel disk electrophoresis without sodium dodecyl sulfate, LTh, LTp, and CT differed in mobility, suggesting differences in their ionic charges. The pI values of LTh, LTp, and CT were 7.50, 8.10, and 6.80, respectively. On sodium dodecyl sulfate-polyacrylamide gel slab electrophoresis, the B subunit and A1 and A2 fragments of LTh, LTp, and CT differed in mobility, suggesting that they differed in molecular size. Their molecular sizes seemed to decrease in the following order: B subunit, LTh greater than LTp congruent to CT; A1 fragment, LTp greater than LTh congruent to CT; A2 fragment, LTh congruent to CT greater than LTp. Amino acid compositions of LTh, LTp, and CT were also compared.

Amino Acids↗
PubMed1981

In vitro formation of hybrid toxins between subunits of Escherichia coli heat-labile enterotoxin and those of cholera enterotoxin.

Heat-labile enterotoxin (LT) was purified from cells of enterotoxigenic Escherichia coli isolated from a patient with traveller's diarrhea. Purified LT was separated into A and B subunits by treatment with 6 M urea solution in 0.1 M propionic acid (pH 4.0). Biologically active toxin was reconstituted from isolated A and B subunits of LT. Hybrid toxins with biological activity were obtained in vitro from the A subunit of cholera enterotoxin and B subunit of LT, and from the A subunit of LT and B subunit of cholera enterotoxin. The hybrid toxins show a similar toxicity to that of the parent toxins from which the A subunits were derived. The in vitro formations of the hybrid toxins were confirmed by polyacrylamide gel disk electrophoresis.

Animals↗
PubMed1981

Modified Elek test for detection of heat-labile enterotoxin of enterotoxigenic Escherichia coli.

The Elek test was modified for detection of the heat-labile enterotoxin of enterotoxigenic Escherichia coli. A total of 164 strains of E. coli were tested by the modified Elek test, and the results correlated well with those of the Chinese hamster ovary cell assay and passive immune hemolysis. It is concluded that the modified Elek test is a simple and reproducible assay method for identification of E. coli which produce heat-labile enterotoxin, and is suitable for use in clinical laboratories.

Bacteriological Techniques↗
PubMed1980

Value of passive immune hemolysis for detection of heat-labile enterotoxin produced by enterotoxigenic Escherichia coli.

The method of passive immune hemolysis of Evans and Evans (Infect. Immun. 16:604-609, 1977) for detection of heat-labile enterotoxin produced by enterotoxigenic Escherichia coli was modified. A total of 373 strains of E. coli were tested by this method using materials obtained by treating the cells with polymyxin B and rabbit antiserum against cholera enterotoxin, purified by affinity gel column coupled with purified cholera enterotoxin, in N-hydroxyethylpiperazine-N'-2-ethanesulfonic acid buffer (pH 6.7). The results correlated very well with those obtained in an assay with Chinese hamster ovary cells. It is concluded that passive immune hemolysis is useful as a routine clinical method for identifying E. coli strains that produce heat-labile enterotoxin.

Animals↗
PubMed1976

Identification of lethal toxin with the thermostable direct hemolysin produced by Vibrio parahaemolyticus, and some physicochemical properties of the purified toxin.

Lethal toxin was purified extensively from the culture filtrate of a Kanagawa phenomenon-positive strain of Vibrio parahaemolyticus. The purified toxin was a protein, and its homogeneity was demonstrated by sodium dodecyl sulfate-polyacrylamide gel disc electrophoresis and analytical ultracentrifugation. It was demonstrated that the thermostable direct hemolysin was identical to the lethal toxin and that it was the main, if not only, lethal toxin in the culture filtrate. The purified toxin had a lethal effect when injected into mice either intravenously or intraperitoneally. Its lethal effect was very rapid, a dose of 5 mug of toxin per mouse killing the animals within 1 min. The lethal activity was inhibited by a ganglioside mixture. Some physicochemical properties of the purified toxin are reported.

Animals↗
PubMed1975

Characterization of the temperature-dependent inactivating factor of the thermostable direct hemolysin in Vibrio parahaemolyticus.

The termostable direct hemolysin of Vibrio parahaemolyticus is inactivated by heating at around 55 C with an inactivating factor isolated from culture filtrates of V. parahaemolyticus. The characteristics of the temperature-dependent inactivating factor were studied by using polyacrylamide gel disc electrophoresis. It was found that when heated with the hemolysin, the inactivating factor destroyed the hemolysin and thus inactivated the hemolytic activity, suggesting that the inactivating factor has proteolytic activity. It was also demonstrated that the inactivating factor itself is heat labile, losing its activity on heating with the hemolysin at 95 C for 15 min. The inactivating factor was stimulated by the presence of NaCl or MgCl2 and showed maximal activity at around pH 8.0. The results support our previous hypothesis that the Arrhenius effect observed with crude hemolysin of V. parahaemolyticus is due to the presence of a temperature-dependent inactivating factor. The fact that the factor is activated on heating at 50 to 60 C but is inactivated on heating at 70 to 100 C explains the Arrheius effect of crude hemolysin of V. parahaemolyticus.

Cell-Free System↗
PubMed1975

Inhibitory effect of L-arginine on growth of rat mammary tumors induced by 7,12-dimethylbenz(a)anthracene.

The effect of L-arginine on growth of rat mammary tumors induced by 7,12-dimethylbenz(a)anthracene was studied. Growth of induced tumors was inhibited by feeding rats an arginine-enriched diet containing 5% L-arginine in addition to the necessary components for rats, including 15% milk casein. The diet significantly reduced both the rate of tumor induction and the number of tumors induced per rat. Histological examination showed that the tumors induced were more benign in rats fed the arginine-enriched diet than in those fed the control diet. A possible mechanism of the inhibitory effect of L-agrinine id discussed.

9,10-Dimethyl-1,2-benzanthracene↗
PubMed1972

Effect of heat (Arrhenius effect) on crude hemolysin of Vibrio parahaemolyticus.

Crude hemolysins prepared from various strains of Vibrio parahaemolyticus, which give positive Kanagawa phenomenon, were partly inactivated by heating at 60 C, but not inactivated significantly by heating at 80 to 90 C. The similar phenomenon has been reported as the Arrhenius effect in staphylococcal alpha toxin.

Gastroenteritis↗