[Molecular structures of preproenkephalins and nicotinic acetylcholine receptor].
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Biomedical subjects
Publications and source records attributed to M Noda.
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Tissue penetration and clinical efficacy were studied on aztreonam (SQ 26,776, AZT) in obstetrics and gynecology with the following results. Number of cases was too small to sufficiently review the penetration into each uterine tissue, the ovary and the tube after the intravenous injection of AZT 1 g. Overall clinical effect for all the 6 cases reviewed was more than "good". Also, neither side effect nor abnormal laboratory findings were reported. From the above results, AZT was considered to be a highly useful antibiotic in obstetrics and gynecology.
Forty-six femora of nine-day-old chick embryos were stimulated by 10 microA of constant direct current via platinum wire electrodes inserted into the diaphyses as cathodes in tissue culture. Apparent calcification in the hypertrophic cartilaginous region of the diaphyses was induced by the electric stimulation. This calcification was most remarkable on both ends of the diaphyses, where fine granules were observed in electron micrographs of the cartilaginous matrix. These granules were aggregates of fine needlelike crystals containing calcium and phosphorous demonstrable by X-ray microanalysis. Incorporation of 45Ca into the femora was significantly increased by the stimulation of up to 247% of the control. This matrix calcification was of interest because it occurred in avian embryonic cartilage that is normally resorbed uncalcified before it is replaced by bone.
Tibial shafts from 15-day-old chick embryos were cultured on chorioallantoic membranes of chick embryos. These bones were stimulated by either constant-direct or constant-alternating current via platinum wire electrodes. Around the anodes of 10 microA constant direct-current stimulation, the number of osteoclasts was significantly larger than that of the control, and numerous osteoblasts were observed. Around the cathodes of this current, periosteum was thickened and accompanied by proliferation of osteoblasts. Slight bone resorption in the immediate vicinity of the cathodes was also observed. The periosteum between the two electrodes was significantly thickened by this current. The comparative study between equivalent constant direct-current and alternating-current stimulation showed a dominance of direct current. This model could be useful in investigations on electrical stimulation of bone in vivo. It produces fewer artifacts and shows activation of osteoclasts in association with activation of osteoblasts in electrically induced reactions of bone tissue.
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Clones harbouring cDNA sequences for the beta subunit precursor of the acetylcholine receptor from calf skeletal muscle have been isolated. Nucleotide sequence analysis of the cloned cDNA has disclosed the primary structure of this polypeptide, which consists of 505 amino acids including a hydrophobic prepeptide of 24 amino acids. The beta subunit of the calf muscle acetylcholine receptor, like the alpha and gamma subunits of the same receptor and the alpha subunit of its human counterpart, exhibits structural features common to all four subunits of the Torpedo electroplax receptor, apparently being oriented across the membrane in the same manner as proposed for the fish receptor subunits. The degree of sequence homology between the calf and Torpedo beta subunits (59%) is comparable to that between the gamma subunits (56%), but is lower than that between the alpha subunits of the two species (81%). Some regions of the beta subunit molecule, including the region corresponding to the putative acetylcholine binding area on the alpha subunit and the region encompassing the clustered putative transmembrane segments M1, M2 and M3, are relatively well conserved between the two species.
Clones carrying cDNA sequences for the gamma subunit precursor of the acetylcholine receptor from calf skeletal muscle have been isolated. Nucleotide sequence analysis of the cloned cDNA has revealed the primary structure of this polypeptide, which consists of 519 amino acids including a hydrophobic prepeptide of 22 amino acids. The gamma subunit of the calf muscle acetylcholine receptor, like the alpha subunit of the calf as well as the human muscle receptor, shares features characteristic of all four subunits of the Torpedo electroplax receptor, such as the putative disulphide bridge corresponding to that in the alpha subunit proposed as being in close proximity to the acetylcholine binding site and the four putative, hydrophobic transmembrane segments M1-M4. Thus, the calf gamma subunit molecule apparently exhibits the same transmembrane topology as proposed for the fish receptor subunits. The degree of sequence homology between the calf and Torpedo gamma subunits (56%) is lower than that between the alpha subunits of the two species (81%). Some regions of the gamma subunit molecule, including the region encompassing the putative disulphide bridge and the region containing the putative transmembrane segments M1, M2 and M3, are relatively well conserved between the two species.
Two flat cellular revertant cell lines, F-2 and C-11, which were originally selected from the DT line of Kirsten murine sarcoma virus (Ki-MuSV)-transformed NIH/3T3 cells, were examined for the production of transforming growth factors (TGFs). The revertant cells fail to grow in semisolid medium as colonies and exhibit a markedly reduced level of tumorigenicity in nude mice, although they are known to express high levels of p21ras, the product of the Kirsten sarcoma virus oncogene, ras, and they contain a rescuable transforming virus. TGF activity associated with the transformed, revertant, and non-transformed cell lines was measured by the ability of concentrated conditioned medium (CM) from these cells to induce normal rat kidney (NRK) and NIH/3T3 cells to form colonies in semisolid agar suspension cultures and to inhibit the binding of 125I epidermal growth factor (EGF) to specific cell surface receptors. CM from the transformed DT cells and from both the F-2 and C-11 revertants contains TGF activity, in contrast to CM obtained from normal NIH/3T3 cells. Furthermore, unlike NIH/3T3 cells, neither the DT nor the revertant cells were able to bind 125I EGF. All four cell lines were able to proliferate in serum-free medium supplemented with transferrin, insulin, EGF, and Pedersen fetuin. However, in basal medium lacking these growth factors, only DT cells and, to a lesser extent, the revertant cells were able to grow. These results suggest that the F-2 and C-11 revertants fail to exhibit all of the properties associated with transformation because the series of events leading to the transformed phenotype is blocked at a point(s) distal both to the expression of the p21 ras gene product and also to the production of TGFs and that the production of TGFs may be necessary but not sufficient for maintaining the transformed state.
The effects of Goniopora toxin (GPT), isolated from the Goniopora species, on the action potential and membrane currents of bullfrog atrial muscle were studied using the double sucrose-gap method. GPT at concentrations above 10 nmol/l prolonged the duration of the action potential and sometimes induced arrhythmias. The prolongation was also induced in the presence of Ca channel blockers (Mn or verapamil). These effects were not reversed by continuous superfusion of GPT-free solution, but were rapidly antagonized by tetrodotoxin (1 mumol/l). The resting potential was not affected by GPT. Voltage clamp experiments revealed that sustained inward current flows following the fast sodium current upon depolarization, in the presence of GPT. The current was elicited by the toxin in Mn-treated fibers and abolished in the presence of TTX. The delayed outward current (Ix) was slightly reduced; the background K current (IK1), inward background current (Ib) and slow inward current (Islow) were not altered by GPT. These results suggest that GPT acts on sodium channels to give rise to a prolonged sodium current which is in turn responsible for the prolongation of the action potential.
The leukocytotoxic toxin pseudomonal leukocidin, produced by Pseudomonas aeruginosa, was radioiodinated with chloramine-T reagent. Binding of [125I]leukocidin to rabbit polymorphonuclear leukocytes was found to be concentration dependent at 37 degrees C. A Scatchard plot of binding data was linear, indicating that leukocidin binds to a single population of sites. The dissociation constant, KD, was calculated from the Scatchard plot to be 2.5 X 10(-7) M, and the number of binding sites per leukocyte was approximately 4.4 X 10(5). Unlabeled leukocidin or antileukocidin antibody reduced the binding of [125I]leukocidin to the leukocytes. A leukocidin-binding protein was extracted from rabbit polymorphonuclear leukocytes with Triton X-100 and purified by leukocidin-Sepharose 4B affinity column chromatography. Approximately 60 micrograms of binding protein was obtained from 8.1 mg of material extracted from the leukocytes. The binding protein had a molecular weight of about 50,000 as shown by sodium dodecyl sulfate-polyacrylamide slab gel electrophoresis and staining with silver nitrate. Under nondenaturing conditions, its molecular weight was also about 50,000, as shown by gel filtration-Sephadex G-200 chromatography. The 50,000-dalton protein purified in this way from rabbit polymorphonuclear leukocytes competitively inhibited the binding of leukocidin to leukocytes and inactivated leukocidin activity. With equimolar amounts of the 50,000-dalton protein and leukocidin, up to 90% inactivation of leukocidin was observed.
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Sulbactam/cefoperazone (SBT/CPZ) was studied for clinical efficacy in the field of obstetrics and gynecology, and following results were obtained: In the treatment of 6 cases of gynecological infection, the clinical efficacy of SBT/CPZ was assessed as excellent in 1 case and effective in 5 cases. Neither adverse effects nor abnormalities in laboratory findings due to SBT/CPZ were observed. Based on these results, SBT/CPZ is considered to be a highly effective antibiotic with clinical efficacy in obstetric and gynecological infections in the daily dosage of 2 g given in two divided doses.
Ceftriaxone (Ro 13-9904, CTRX) was studied about the tissue transfer in the gyneco-obstetric field and the following results were obtained. The transfer of CTRX into the uterine tissues and adnexa was favorable following an intravenous injection with 1 g. The mean serum level 1 hour after administration was 123.3 micrograms/ml while the tissue level ranged from 26 to 48 micrograms/g. The level in the pelvic dead space exudate reached a peak 3 to 6 hours after administration and got higher than the serum level at 5 to 6 hours.
Ceftazidime ( CAZ ), a new cephalosporin antibiotic, was studied for transference into tissues and clinical efficacy in the field of obstetrics and gynecology, and the following results were obtained: After one shot intravenous injection of CAZ 1 g, favourable transference of CAZ into uterine tissues was observed. While the mean serum level at 1 hour after the administration was 50.2 micrograms/ml, the levels in oviduct, ovary, endometrium, myometrium, cervix uteri and portio vaginalis were 25.9, 31.6, 24.9, 24.5, 34.2 micrograms/g and 40.6 micrograms/g, respectively. The half-life of CAZ in these tissues ranged from 1.16 to 1.65 hours while that in serum was 1.24 hours. The peak level in retroperitoneal space exudate (25.3 micrograms/ml) was obtained at 3 hours after one shot intravenous injection of CAZ 1 g. The level was still as high as 2.68 micrograms/ml even 12 hours after the administration. Out of 4 cases of obstetric and gynecological infections, 3 cases were assessable, CAZ was effective in these 3 assessable cases. Neither adverse effects nor abnormalities in laboratory findings due to CAZ were observed. Based on these results, CAZ is considered to be an highly effective antibiotic with good transference into uterine tissues and clinical efficacy in obstetric and gynecological infections.
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Scanning electron microscopy of granulosa cells (GC) and granulosa cell-like structures (GCLS) revealed that both had lacy foldings, or plicae, on the surface and were identical. The plicae did not always cover the entire surface of GC or GCLS. Both structures were interconnected by multivalent processes.