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Biomedical subjects

M Kasai

Publications and source records attributed to M Kasai.

At least 397 records · Page 22Linked to original sources
PubMed1986

Determination of the rate of rapid pH equilibration across isolated sarcoplasmic reticulum membranes.

The rate of the transmembrane pH equilibration in the isolated vesicles of sarcoplasmic reticulum of skeletal muscle after extravesicular pH jump was determined for the first time. A highly water-soluble pH sensitive fluorescent dye, 8-hydroxy-1,3,6-pyrenetrisulphonic acid (pyranine), was used as intravesicular pH indicator in the stopped-flow fluorophotometry. The pH of the medium was controlled with 20 mM HEPES-K or PIPES-K. The fluorescence intensity changed monophasically as much as expected from its pH dependency for imposed delta pH. The half time for initial pH of 7.53 or 6.83 was about 6 msec. The H+/OH- permeability was 11 cm/sec. The results suggested that each vesicle contained large numbers of H+/OH- channels.

Animals↗
PubMed1986

Electrophysiological properties of neurons in the caudal ventrolateral medulla projecting to the paraventricular nucleus of the hypothalamus in rats.

Extracellular recordings were made from neurons in the caudal ventrolateral medulla in urethane-chloralose-anesthetized rats. Stimulation of the paraventricular nucleus (PVN) in the hypothalamus evoked antidromic action potentials in 71 neurons. On the basis of antidromic spike latencies, these neurons could be divided into fast- (24 neurons) and slow-conducting cell groups (47 neurons). Slow-conducting cells showed irregular and slow spontaneous discharges, while a majority of the fast-conducting cells did not show spontaneous discharges. The spontaneous activity of slow-conducting cells was suppressed by i.v. clonidine administration. The effects of clonidine could be consistently reversed by administration of the alpha 2-adrenergic antagonist, yohimbine. The responses by clonidine and yohimbine remained unimpaired in baroreceptor-denervated rats. Vagus nerve stimulation produced an excitation in 80% of slow-conducting cells tested. Baroreceptor activation induced by i.v. administration of phenylephrine inhibited about half of slow-conducting cells tested. Similar elevation of blood pressure in baroreceptor-denervated rats did not show any effect. These physiological and pharmacological properties of slow-conducting cells were similar to those previously reported for catecholaminergic cells in other parts of the brain. The results show the existence of two different populations among neurons in the caudal ventrolateral medulla which project directly to the PVN, and suggest that the presumed A1 catecholaminergic cells are involved in the afferent pathway from cardiovascular baroreceptors and the vagus nerve to the PVN.

Animals↗
PubMed1986

Development of highly immunogenic variants of a rat fibrosarcoma line during in vitro cultivation.

Rat fibrosarcoma KMT-17 cells decreased in tumorigenicity when cultured in vitro. Eight clones derived from cultured KMT-17 cell lines (c-KMT-17) were examined for their tumorigenicity, immunosensitivity, and immunogenicity. All the clones were less or nontumorigenic in normal syngeneic rats than KMT-17 cells maintained in vivo. All eight clones produced tumors in rats immunosuppressed with 600 rad 60Co; differences in degree of tumorigenicity were seen among clones in rats irradiated with 250 rad 60Co. Although immunosensitivity of the eight clones to complement-dependent and cell-mediated cytotoxicity was the same or less than that of KMT-17 cells, al leight clones induced greater transplantation resistance to KMT-17 than KMT-17 itself. Cold target inhibition tests demonstrated new antigens in a highly immunogenic variant in addition to the original tumor associated antigen (TAA). New glycolipids, not observed in KMT-17 cells, were demonstrated in the clones by thin layer chromatography. These results suggest that new antigens appearing during culture of KMT-17 may act as helper antigens for TAA, increasing the immunogenicity and decreasing the tumorigenicity of the cultured cells.

Animals↗
PubMed1986

Significance of serum lipoprotein-X and gammaglutamyltranspeptidase in the diagnosis of biliary atresia. A preliminary study in 27 cholestatic young infants.

As simple and nonsurgical means of differentiating biliary atresia (BA) from intrahepatic cholestasis of unknown origin (IC), liver function tests including serum lipoprotein-X (LP-X) and gamma-glutamyltranspeptidase (GGTP) were done and evaluated for their usefulness in the diagnosis of 27 cholestatic Japanese young infants. Except for LP-X and GGTP levels (P less than 0.01, P less than 0.001), there were no significant differences between the BA (n = 11) and IC (n = 13) groups. When values of mean plus 4 standard deviations were used to differentiate BA from IC (89 mg/100 ml for LP-X and 194 IU/l for GGTP), all BA patients gave positive results for either the critical LP-X of GGTP values. On the other hand, all IC patients gave negative results for both levels, although patients with a paucity of intrahepatic biliary ducts (n = 3) were also positive for either the critical LP-X or GGTP values. The combination test with serum LP-X and GGTP is recommended for helping to differentiate BA from IC in cholestatic young infants.

Bile Ducts↗
PubMed1986

Nonfreezing technique for short-term storage of mouse embryos.

Mouse morulae were stored at 0 degrees C in the medium containing various sugars, and their effect on the embryonic viability was examined. The longevity of the embryos was considerably extended, if a hexose or a disaccharide was supplemented in the medium. The most effective concentration appeared to be 0.5-0.75 M, irrespective of the molecular weight. Glucose, galactose, fructose, sucrose and lactose were more effective than mannose and maltose. Considering that the embryos stored with sugars were recovered shrunken, the beneficial effect of sugars seemed to be from proper dehydration of the cells caused by osmotic pressure afforded by a non-toxic and non-permeable non-electrolyte. The non-freezing technique using a sugar could also be used combined with a freezing technique, if 1-6 h of incubation is incorporated between the two treatments. If the non-freezing technique prove to be available to the embryos of domestic animals, it will practically be more useful.

Animals↗
PubMed1986

Structure of the two genes coding for polypeptide chain elongation factor 1 alpha (EF-1 alpha) from Saccharomyces cerevisiae.

Polypeptide chain elongation factor 1 alpha (EF-1 alpha) of Saccharomyces cerevisiae is encoded by two distinct genes designated EF1 alpha A and EF1 alpha B [Nagata et al., EMBO J. 3 (1984) 1825-1830]. Both genes were cloned, and their nucleotide (nt) sequences were determined [see also Schirmaier and Philippsen, EMBO J. 3 (1984) 3311-3315, and Cottrelle et al., J. Biol. Chem. 260 (1985) 3090-3096]. They contain an open reading frame of 1374 nt coding for an identical protein of 458 amino acid residues, although their nt sequences differed at two positions. In this paper, we determined their 5'- and 3'-flanking sequences which were considerably different each other. From the S1 nuclease mapping of mRNA, both genes are found to be expressed almost to the same extent in exponentially growing cells. The transcription start points for EF1 alpha A and EF1 alpha B mRNAs were precisely located by primer extension procedure at 32 and 23 nt upstream of the start codons, respectively. The sequence which commonly exists in the 5'-flanking regions of ribosomal protein genes of S. cerevisiae was also present in the two EF1 alpha genes.

Amino Acid Sequence↗
PubMed1986

Postoperative changes of intrahepatic portal veins in biliary atresia--a 3-D reconstruction study.

Intrahepatic portal veins were reconstructed from serial histologic sections of surgical liver specimens from patients with biliary atresia to explain the pathogenesis of portal hypertension, an important late postoperative complication of this disease. It was found that abnormal intrahepatic vasculature was already notable in an evidently reduced number of portal veins in the second month of age, and this was considered responsible for causing presinusoidal block that gave rise to the elevated resistance to intrahepatic portal flow. Reconstruction also revealed that restoration of ordinary portal structure was expectable if, after successful surgery, a patient was sufficiently protected from cholangitis and there was much room for portal veins to grow without being impeded by inflammatory and/or scarring processes. In contrast, the patient whose condition was complicated by cholangitis was shown to acquire a markedly hypoplastic portal system with apparently reduced vascularity.

Bile Ducts↗
PubMed1986

Portal hypertension after successful hepatic portoenterostomy in biliary atresia.

From 1953 through 1984, we have operated on 225 cases of biliary atresia, and 95 patients are presently surviving. Portal hypertension with esophageal varices was endoscopically confirmed in 26 of 66 patients (39%) examined, 14 with and 52 without jaundice. All these patients except two had had frequent episodes of postoperative cholangitis. Eight patients have undergone treatment for portal hypertension. The treatment for variceal bleeding in jaundice-free infants with biliary atresia should be initiated conservatively, including endoscopic sclerotherapy. The results of our experience, however, justifies the employment of shunt procedures for patients older than 6 or 7 years of age.

Adolescent↗
PubMed1986

Reconstitution of sarcoplasmic reticulum Ca2+-ATPase vesicles lacking ion channels and demonstration of electrogenicity of Ca2+-pump.

Sarcoplasmic reticulum (SR) vesicles were reconstituted by the salting out method in the presence of excess phospholipids: the lipid-to-protein ratio ranged from 10 to 100. It was found that the reconstituted vesicles could be separated by KC1 density gradient centrifugation into four types: those having both cation and anion channels (CASR), those having only cation channels (CSR), those having only anion channels (ASR), and those having no ion channels (PSR). From the yield of these vesicles, it was estimated that one native SR vesicle contains 19 cation channels and 1.4 anion channels on average; the amount of cation channels is 14 times larger than that of anion channels. Although all vesicles thus prepared are considered to contain the Ca2+-ATPase protein, the PSR vesicles alone did not take up Ca2+, but they did do so in the presence of valinomycin. This result indicates that the Ca2+-ATPase takes up Ca2+ in an electrogenic manner. The electromotive force was estimated to be about 50 mV.

Animals↗
PubMed1986

The activity of suppressor cells in the spleen of murine bone marrow chimeras.

An intrasplenic injection (i.s.) of BALB/c bone marrow cells induces a higher survival rate than an intravenous injection (i.v.) in irradiated C3H/He recipients. Coculture experiments revealed the presence of alloantigen-specific and nonspecific suppressor cells in the spleens of mice injected i.s. and i.v. Suppressor activity decreased 50-60 days after bone marrow transplantation in i.v. chimeras, while there was no decrease in i.s. chimeras. In vitro suppressor activity was correlated with in vivo activity. Histopathological changes in the liver were examined. A total of 28% of the i.v. chimeras showed severe changes compared with 6% of the i.s. chimeras. The spleen indices of i.v. and i.s. chimeras were compared. Although there was no statistically significant difference between the spleen indices of i.v. chimeras and those of i.s. chimeras, spleen indices of i.v. chimeras tended to be higher than those of i.s. chimeras. These results show that suppressor cells in i.s. chimeras appear to inhibit graft-versus-host reactions more efficiently. Furthermore, an adoptive transfer assay showed that suppressor cells detected in i.s. chimeras were effective in vivo. We therefore suggest that suppressor cells detected in vitro correlate with in vivo activity and may play some role in the induction and maintenance of transplantation tolerance.

Animals↗
PubMed1986

Bio-medico-mechanical behavior of natural artery blood vessel under constant and variable internal pulsatile pressure flow test in vitro.

Studies have been carried out on the bio-medico-mechanical behavior in vitro of natural blood vessel (dogs) under constant and variable internal pulsatile pressure flow. The apparatus designed by us well simulated the arterial system. The studies were made for the case of pressure amplitude kept as constant, of the two-step-multi-duplicated pulsatile pressure and of the fluctuating pressure. For the case of the fluctuating pressure, the strength of the artery becomes considerably lower than those under constant amplitude and two-step-multi-duplicated pulsatile pressure. SEM observations of the inner walls of the artery shows that collagen fibers are more elongated under fluctuating pulsatile pressure flow. In conclusion, in order to avoid the mechanical deterioration of the artery strength, it is useful to keep the pulsatile blood pressure at constant amplitude. Even for the case of the blood pressure fluctuation, it is necessary to manage to keep the blood pressure as near a regular wave as possible, the total number of repeated pulse being equal.

Animals↗
PubMed1986

Electric pulse-mediated gene transfer in mammalian cells grown in suspension culture.

A high-voltage generating machine which could generate semi-rectangular pulses in PBS solution was constructed, and the effects of field strength and duration of the pulse on electric pulse-mediated transformation of mouse mammary carcinoma FM3A cells by a linear form of plasmid pSV2neo DNAs were examined. In parallel, cell survival and growth after pulsing were analyzed. When the field strength and duration of the pulse were increased, the transformation frequency increased, although the cell survival rate decreased. Under the best conditions, the transformation frequency was 2 X 10(-4), which was 80 times higher than that obtained by the calcium phosphate coprecipitation method.

Animals↗
PubMed1986

Liver transplantation in dogs after 30 minutes of warm ischemia.

In order to investigate the applicability of liver transplantation after warm ischemia, a partial auxiliary auto-transplantation of the liver after 30 min of warm ischemia was carried out in 9 mongrel dogs. Among them, 6 dogs survived longer than 7 days. Liver functions, blood coagulability and histological changes were investigated before and after the transplantation. Serum GOT, LDH, and GPT levels were elevated immediately after transplantation, and returned to normal within a few days. Hemostatic tests also showed significant abnormalities after transplantation. Although PT and thrombotest became normal within a week, PTT and antithrombin III remained slightly abnormal for longer periods. Microscopically, vacuolization and degeneration of hepatocytes were observed after transplantation but they recovered completely within 4 weeks. Based on these results, it could be said that the livers subjected to warm ischemia for 30 min ischemia were still acceptable for auxiliary transplantation.

Animals↗
PubMed1986

[The effect of an arginine-imbalanced diet on the growth of implanted MM-48 and MH-134 tumors in C3H/He mice].

The arginine-imbalanced diet used in this study was a diet of 27% casein supplemented with 8% arginine monochloride. There was no difference in the serum protein level between C3H/He mice fed a casein diet (N-mice) and mice fed on the arginine-supplemented diet (A-mice). The serum arginine level was increased in the A-mice compared with the N-mice. Significant inhibition of MM-48 tumor incidence was seen in the A-mice when the transplanted tumor was below 5 X 10(6) cells. Growth inhibitory effect against MM-48 tumor was significantly enhanced in the A-mice with i.p. injection of OK-432. Interferon production of spleen cells was increased in the A-mice compared with the N-mice. We speculate that the effect of arginine depends partially on the immune functions in the mice.

Amino Acids↗
PubMed1986

[Interferon production in lymph nodes draining breast carcinoma and its augmentation by OK-432].

In breast cancer patients on whom modified radical mastectomy is performed, relatively more of the regional lymph nodes draining the breast carcinoma remain in comparison with standard radical mastectomy. Therefore, investigation of the functions of lymph nodes draining breast carcinoma has become important. Lymphocyte subsets of 33 axillary lymph nodes from 19 breast cancer patients were analysed using flow cytometry. In axillary lymph nodes, both OKT-3(+) cells and OKT-8(+) cells were decreased in comparison with those in peripheral blood. However, the OKT 4/8 ratio was increased in axillary lymph nodes. These findings suggest that axillary lymph nodes are immunologically more functional against cancer spread than peripheral blood. OK-M1(+) cells, Leu-7(+) cells and Leu-11a(+) cells were decreased in axillary lymph nodes in comparison with peripheral blood. The ability of IFN production in axillary lymph nodes and peripheral blood was analysed using the cytopathic effect of VSV-sindbis virus. After 72 hours incubation, IFN production of axillary lymph nodes showed maximum titer. When lymph nodes were co-cultured with OK-432, IFN production of axillary lymph nodes was strongly augmented. IFN production of axillary lymph nodes draining breast carcinoma were increased in comparison with peripheral blood. Axillary lymph nodes draining breast carcinoma would thus seem to be important as cytokine-producing organs. IFN has been found to be an activator of NK cells, cytotoxic T cells and IL-2 production. Axillary lymph nodes may therefore play an important role against the spread of breast cancer.

Axilla↗