Biomedical subjects
Publications and source records attributed to T Nishimura.
Of 52 serum samples from infertile women tested against isolated porcine oocytes by immunofluorescence, 8 produced intense reactions in zonae pellucidae, while only one of 52 sera from control subjects showed the reaction. Autoantibodies to the zona may be present in these women.
beta-Ketothiolase from Zoogloea ramigera I-16-M was purified 140-fold to electrophoretic homogeneity. The bacterium appeared to contain a single isoenzyme of beta-ketothiolase with a molecular weight of 190 000, as determined by Sephadex G-200 gel filtration. The monomer molecular weight was 44 000, as estimated by polyacrylamide gel electrophoresis in the presence of sodium dodecyl sulfate. The native enzyme thus appeared to be a tetramer with identical subunits. The enzyme showed a pH optimum of 7.5 in the condensation reaction, and 8.5 in the thiolysis reaction. The enzyme employed a Bi Bi ping pong mechanism for the forward thiolysis reaction. The apparent Km value for acetoacetyl coenzyme A in the thiolysis reaction was 10 micron, and that for coenzyme A was 8.5 micron. The apparent Km value for acetyl coenzyme A in the condensation reaction was 0.33 mM. The condensation reaction was inhibited by coenzyme A concentrations lower than 0.1 mM. The enzyme was stable in the presence of dithiothreitol and other SH-compounds, but was strongly inhibited by 0.4 mM p-chloromercuribenzoate.
Differences in suiciding by various tritiated nucleosides were observed between two functional assays for in vitro lymphocytic precursor cell development, the hemolysin plaque-forming cell (PFC) assay and the B lymphocytic colony-forming cell (CFC-L) assay, using BDF1 mouse spleen cells. PFC growth was markedly reduced by an early (days 0-1) pulse of tritiated deoxyadenosine ([3H]dAdo), but relatively unaffected by a pulse of tritiated thymidine ([3H]dThd) during the same interval. In contrast, CFC-L formation significantly dropped after an early (day 0) [3H]dThd pulse, as well as after pulses of [3H]dAdo and the corresponding tritiated ribosides, uridine and adenosine. This implied a cycling state in an early lymphocytic precursor cell, as opposed to the PFC insensitivity to an early [3H]dThd pulse. The response pattern of colonies and clusters to [3H]dThd supported our notion of a delayed suiciding of CFC contributing to the increase in cluster numbers.
X-irradiation was used as a tool to investigate the radiosensitivity of different B and T precursor subpopulations as detected by three in vitro culture systems. The culture systems utilized in this study included antigen reactive cell assays (ARCA), polyclonal mitogen assays (PMA), and polyclonal effector cell assays (PECA). The order of radiosensitivity of these systems in both the B and T cell series was ARCA greater than PMA greater than PECA (D37 values for B cell responses: ARCA = 88.8 R, PMA = 125 R, PECA = 223 R; D37 values for T cell responses: ARCA = 160 R, PMA = 441 R and PECA = 1095 R). With all assay systems the B cell response was more radiosensitive than the T cell response. The extrapolation number (n) from the radiation survival curves was approximately 2.0 for T cell responses and approximately 1.0 for B cell responses. The value of 1.0 for B cell responses suggest that their extreme radiosensitivity may be due in part to a lack of repair mechanisms. These findings also suggest that the more primitive precursor cells are more apt to undergo cellular proliferation upon activation and that this event is more radiosensitive than is the final differentiation event of precursor cells into a progeny of functional end-stage cells.
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The effect of genetical dissimilarity between the trophoblast and host on trophoblast growth was studied in extrauterine sites, where people can observe trophoblast growth without the complicating factors of the uterine environment. Trophoblast growth was estimated in this study by measuring the extent of trophoblast proliferation in the kidney and testis per body weight in the testis. The results showed that the trophoblast growth was not enhanced by genetical dissimilarity, but was probably determined by the capacity of the host to support trophoblast growth and the capacity of the trophoblast itself to grow. No hormonal influence on trophoblast growth was observed. When hosts were immunized with double skin grafts from donors, however, the success rate of attempted transplantation of the blastocyst was remarkably lowered and trophoblast growth was also suppressed in terms of the number of trophoblast cells and the extent of trophoblast proliferation. In such cases, intensive lymphocytic infiltration was seen between the trophoblast and host tissues. This suggests that some antigenicity on the trophoblast may be expressed in vivo under some conditions, e.g., in the strongly immunized host by the donor's antigen and the immunity to this antigen suppresses trophobalst growth.
To investigate steroidogenic function of human follicles in the light of their structures, eight antral follicles of different sizes were mechanically isolated from ovaries of patients laparotomized in the follicular phase of the menstrual cycle with or without pretreatment with human menopausal gonadotropin (hMG). A portion of each follicle was taken for histology and slices of each follicle were incubated with [1-14C]-acetate. Incorporation into progestins, androgens, and estrogens was assessed by the reverse dilution technique with recrystallization to constant specific activity. A predominant incorporation into 17 beta-estradiol was observed in two maturing follicles, whereas a marked increase in incorporation into 17 beta-estradiol with a concomitant decrease in incorporation into androstenedione was verified in two other mature follicles. Remarkable enhancement in relative incorporation into C21 steroids was commonly noted in four preovulatory follicles. However, with the progress of preovulatory stages toward ovulation, as judged from structural changes of the follicles, actual incorporation into C19 and C18 steroids showed a moderate increase, followed by a drastic decrease around the time of ovulation. hMG injection induced similar relationships between the steroidogenic pattern and the follicle structure of different stages, although overall incorporation was considerably increased. We conclude that marked qualitative and quantitative changes in the steroidogenic function and accompanying corresponding changes in structure occurred over the period of follicular maturation and ovulation.
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To investigate the mechanism of the cough-like reflex (CLR), we employed 1.1-dimethyl-4-phenylpiperazinium iodide (DMPP). In dogs anesthetized with alpha-chloralose, CLR was induced by administration of DMPP (i.v. and intracarotid arterial), lobeline and nicotine. Repeated administration of DMPP did not cause a tachphylaxis, however, lobeline and nicotine did induce a tachphylaxis. DMPP (i.a.), lobeline, nicotine and histamine caused an increase in respiratory resistance as measured by a Respiratory Resistance Meter, while DMPP (i.v.) did not. The ED50 of morphine, codeine, oxymethebanol, picoperidamine and piclobetol on CLR with DMPP was higher than that of those drugs employed for the peripherally-induced cough. CLR with DMPP was not affected by isoproterenol, ephedrine, atropine and propranolol. CLR was markedly depressed by hexamethonium and slightly depressed by benzonate. CLR was abolished after bilateral vagotomy or bilateral denervation of the carotid sinus nerves. These results indicate that the mechanism of CLR with DMPP is different from that of peripherally-induced cough and the carotid body chemoreceptor plays an important role in CLR with DMPP. This CLR may be useful for demonstrating the site of action and the mechanism of antitussive drugs.
Subtracted nephrogram was developed using 131I-hippuran sequential scintigraphy. An Anger-camera and on-line minicomputer system (HITAC-10, 16KW) was employed for data processing. In the present study, after 500microCi of 131I-hippuran was injected intravenously, sequential images were stored as 10-second frames of digitalized data for 20 minutes and these images were transferred into the magnetic tape. RI dynamic curves in the areas of interest such as substantial and pelvic regions were extracted by comparison with regional renograms with varimax method. Subtracted nephrogram was attempted which calculated the differences in RI concentration between two images of substantial and pelvic phase in the digitalized image and displayed as functional images on a CRT. These methods were applied clinically in various renal diseases. It was demonstrated that subtracted nephrogram was proved to be a method by which the dynamic process of renal function was represented by a single display. And subtracted nephrogram was shown to delineate the functioning renal substance and pelvis clearly and to correspond with the findings of pyelography. In conclusion, these method seemed to be useful for quantitative evaluation of substantial or pelvic function and for the differential diagnosis of various renal diseases.
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The effects of macromomycin (MCR), a high molecular weight peptide antibiotic, on cell division, DNA synthesis and DNA fragmentation were examined in cultured mammalian tumor cells. When MCR was added to HeLa cell culture simultaneously with [3H]thymidine, inhibition of DNA synthesis was observed depending on the amount of the drug present, although the inhibition was partial even at a high concentration of the drug. Preincubation of cells with MCR for 2 hours before assay was required for the complete inhibition of DNA synthesis. Cell division of synchronized L5178Y cells, arrested at metaphase, was strongly inhibited by MCR, indicating that the inhibition of cell mitosis by the drug was not dependent on the inhibition of DNA synthesis. Strand scission of DNA in MCR-treated cells was observed by alkaline sucrose gradient centrifugation. The fragmentation of cellular DNA occurred at low concentration of the drug and within a very short incubation time (37 degrees C, 5 minutes). At high concentrations of the drug, however, the size of the fragmented DNA remained constant. DNA polymerase activity in isolated nuclei from HeLa and L5178Y cells was stimulated by MCR. These data suggest that MCR works directly on cell nuclei and strand scission of DNA is one of the more important actions of the drug.
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