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Biomedical subjects

M Nishimura

Publications and source records attributed to M Nishimura.

At least 1,315 records · Page 73Linked to original sources
PubMed1982

Isolation and characterization of metabolically competent mitochondria from spinach leaf protoplasts.

Intact mitochondria were prepared from spinach (Spinacia oleracea L. var. Kyoho) leaf protoplasts and purified by Percoll discontinuous gradient centrifugation. Assays of several marker enzymes showed that the final mitochondrial preparations obtained are nearly free from other contaminating organelles, e.g. chloroplasts, peroxisomes, and endoplasmic reticulum. These mitochondria oxidized malate, glycine, succinate, and NADH, tightly coupled to oxidative phosphorylation with high values of ADP to O ratio as well as respiratory control ratio. The rate of NADH oxidation was 331 nmoles O(2) per milligram mitochondrial protein per minute, which is comparable to that obtained by highly purified potato or mung bean mitochondria. However, the activity of glutamine synthetase was barely detectable in the isolated mitochondrial fraction. This finding rules out a hypothetical scheme (Jackson, Dench, Morris, Lui, Hall, Moore 1971 Biochem Soc Trans 7: 1122) dealing with the role of the mitochondrial glutamine synthetase in the reassimilation of NH(3), which is released during the step of photorespiratory glycine decarboxylation in green leaf tissues, but it is consistent with the photosynthetic nitrogen cycle (Keys, Bird, Cornelius, Lea, Wallsgrove, Miflin 1978 Nature (Lond) 275: 741), in which NH(3) reassimilation occurs outside the mitochondria.

Journal Article↗
PubMed1982

Developmental formation of glutamine synthetase in greening pumpkin cotyledons and its subcellular localization.

During the germination of pumpkin (Cucurbita sp. Amakuri Nankin) seeds in dark, the activity of glutamine synthetase in cotyledons gradually increased, reaching a maximum at 5 to 6 days. A measurable enhancement (about 4-fold) of the enzyme activity occurred when the seedlings were exposed to continuous illumination from day 4 up to day 8. Glutamine synthetase activity was detectable only in the cytosolic fraction in the etiolated cotyledons, whereas it was found both in the cytosolic and chloroplast fractions in the green cotyledons. The two isoenzymes of glutamine synthetase have been separated by DEAE-cellulose column chromatography of extracts from the green cotyledons. These data indicate that during the greening process the chloroplastic glutamine synthetase is newly synthesized. The roles of cytosolic and chloroplastic glutamine synthetase in germinating pumpkin cotyledons concerning assimilation of NH(3) are discussed.

Journal Article↗
PubMed1982

Suborganellar localization of proteinase catalyzing the limited hydrolysis of pumpkin globulin.

Protein bodies were prepared from the cotyledons of pumpkin (Cucurbita sp.) seeds by employing a nonaqueous isolation method. Both light micrographic examination and the marker enzyme assays have shown that the isolated protein bodies were intact and contamination with other cell organelles or cytoplasmic components was negligible. A proteolytic enzyme catalyzing the limited hydrolysis of carboxymethylated gamma' chain of globulin was found to be present in the protein bodies. The specific activity in the protein body (18 units per milligram protein) was higher than that in the whole cell extract (13 units per milligram protein), indicating that the limited proteolytic enzyme was localized in the protein body.After lysis of the protein bodies using hypotonic buffer solution, the suborganellar components (matrix, membranes, and crystalloids) were separated by sucrose density gradient centrifugation. The crystalloid was composed of only globulin, a major seed protein. The major proteins of matrix and membrane fractions were shown to have mol wt of approximately 10,000. About 90% of the limited proteolytic activity was found in the matrix region.

Journal Article↗
PubMed1982

pH in Vacuoles Isolated from Castor Bean Endosperm.

Vacuoles were prepared from germinating castor bean endosperm (Ricinus communis var Hale) and purified by filtration through a cotton layer under physiological osmolarity. The purity of vacuoles prepared by this method was comparable with that prepared by a sucrose step gradient centrifugation reported in a previous paper (Nishimura, Beevers 1978 Plant Physiol 62: 44-48). It was shown by assays of marker enzymes that the final preparation contained trace contamination of other organelles (glyoxysomes, mitochondria, and endoplasmic reticulum) and the cytosol. The isolated vacuoles were stained with neutral red, indicating that the intravacuolar pH is acidic. Intravacuolar pH of isolated vacuoles was determined by measuring the distribution of [(14)C]methylamine in the vacuoles and by directly measuring the pH of vacuolar extracts. The pH of isolated vacuolar extracts was 5.7 to 5.9. Similar values were obtained by the methylamine method and it was shown that intravacuolar pH increased as the pH of the medium was increased.

Journal Article↗
PubMed1982

Autotransplantation of hepatic granulomas into the skin of mice with Schistosoma mansoni infection.

Hepatic egg granulomas of mice infected with Schistosoma mansoni were transplanted into the skin of the same animal and changes occurring to macrophages, eosinophils, and mast cells over time were studied by light and electron microscopy and by autoradiographic techniques. Disappearance of cellular components about the egg granulomas occurred within 1 week; the entire implant became encapsulated by inflammatory cells and stroma. By 3 weeks mononuclear cells and macrophages reorganized the granulomas around the eggs and neutrophils disappeared. Activated macrophages contained both secretory rough endoplasmic reticulum and lysosomal-dense bodies. Granuloma size increased up to 5 weeks after implantation and mast cells and eosinophils tended to migrate into the granulomas. The mast cell index always remained lower than in the original hepatic granulomas, while eosinophils were seen in large numbers. During 3 to 8 weeks after implantation mononuclear cells undergoing DNA synthesis in the granulomas ranged from 2.9-4.8%. Some 3-week-old autotransplants were injected with 3H-thymidine and biopsied from 1 to 21 days later. Labeled mononuclear cells peaked in the granulomas by 10 days (24%) and the numbers fell off sharply after that. These findings indicate that autologously implanted schistosome egg granulomas can be maintained successfully in the skin for prolonged periods with marked ingress of macrophages and eosinophils. The autoradiographic data suggest the lesions are high turnover granulomas.

Animals↗
PubMed1982

Mechanism of cadmium-induced contraction in ileal longitudinal muscle of guinea-pig.

1 The mechanism of cadmium (Cd2+)-induced contraction was studied in isolated ileal longitudinal muscle of guinea-pig. 2 CdCl2 (1x10(-8) to 1x10-4M)) caused a transient contraction which subsided within approximately 6 min of application. The contraction was reproducible and dependent on the concentration. The dose-response curve was bell-shaped. A maximal response was observed at concentrations of 5x10(-6) to 1x10(-5) M. 3 The contractile effect was inhibited to some degree at 20 degree C or by tetrodotoxin (0.1 microgram/ml), hyoscine (o.1 microgram/ml), but completely inhibited by Ca2+ -removal from the medium. 4 Cd2+ increased the output of [14C]-acetylcholine biosynthesized from [14C] by the preparation depending on the concentration. The increase terminated within the first 6 min and was reduced by tetrodotoxin (0.1 microgram/ml) or by removal of Ca2+ from the medium. 5 Both the contractile and transmitter releasing effects of Cd2+ were dependent on the concentration of external Ca2+. Strontium ions were able to replace Ca2+ -induced transmitter release. 6 It is suggested that Cd2+ contracts ileal longitudinal muscle through a release of cholinergic transmitter from the parasympathetic nerve terminals, which is dependent on external Ca2+. It also has a smaller hyoscine-resistant contractile effect, presumably due to a direct action on smooth muscle cells.

Acetylcholine↗
PubMed1982

Retinal vascular patterns in the macula and the perimacular area in premature and full-term infants.

27 eyes of 20 premature and full-term infants were subjected to trypsin digestion, and a study was made of the extension of the temporal retinal vessels and of the formation of the radial peripapillary capillaries (RPCs) and the capillary-free zone in the macula. The advancing borders of the temporal retinal vessels exhibited a V-shaped appearance in cases of 23-29 weeks in gestational age. The RPCs were observed in cases after the 27th week of gestation. The capillary-free zone in the macula was observed in cases after the 25th week of gestation. There were two eyes having extremely small and incomplete capillary-free zones: in one eye a vascular network was present in the region corresponding to the center of the macula. It was thought that the vascular network in the temporal horizontal aspect of the macula is formed by anastomosis of the superior and inferior temporal vessels, and that the capillary-free zone in the macula develops secondarily as the result of retraction of the capillaries.

Gestational Age↗
PubMed1982

Potentiation of indirectly induced muscle twitches by organic calcium antagonists in phrenic nerve-diaphragm muscle preparations of mice.

Organic calcium antagonists (l- and d-verapamil, D600, and diltiazem) were examined for their effects on muscle twitches of isolated phrenic nerve-diaphragm muscle preparations of mice. The calcium antagonists (1 x 10(-6) to 7.5 x 10(-5) M) increased the amplitude of muscle twitches induced by nerve stimuli with short durations (0.04 to 0.4 msec) of rectangular pulses. However, these agents were poorly effective on twitches induced by nerve stimuli with longer durations over 0.6 msec or by direct shocks. The potentiative effect was reversible, reproducible and dependent on their concentrations. Diltiazem was the most effective among the four agents tested. The twitch increase produced by all of the agents was demonstrated at concentrations of external Ca++ above 0.6 mM. At Ca++ concentrations below 0.5 mM, the tension of the indirectly induced muscle twitch was partially inhibited in the presence of these agents. Caffeine, theophylline, isoproterenol or hypertonic potassium ions increased the tension of indirectly induced muscle twitches. The potentiative effect of the organic calcium antagonists, however, was discriminated from those induced by the other agents under some conditions. From these results, it is suggested that the organic calcium antagonists alter the reactivity of the preparation to nerve shock. The potentiative effect of the agents on indirectly induced muscle twitch may include an increase in the number of fibers contracting per nerve impulse through increasing transmitter release from the nerve terminal, but not an increase in contractility of an individual muscle fiber.

Animals↗
PubMed1982

Verapamil-induced transmitter release in rat diaphragm muscle.

Verapamil was examined for its effect on the frequency of miniature end-plate potential (m.e.p.p.) in rat diaphragm muscles. Verapamil (5 x 10(-5) M) raised the m.e.p.p. frequency. This effect was reversible, reproducible, and concentration dependent. The rise in the frequency was maintained in the presence of external Ca++ but was transient in the absence of external Ca++. Lowering the temperature to 20 degrees C slightly decreased the average frequency of m.e.p.p. in the normal medium. The effect of verapamil was also present at a low temperature but was delayed in its onset. The resting membrane potential of the muscle fiber was not affected by the agent. These results suggest the possibility that verapamil increases the transmitter release from motor nerve terminals, and the effect is possibly due to a release of Ca++ for its initiation, but is dependent on external Ca++ for its maintenance.

Animals↗
PubMed1982

Effects of verapamil and manganese ion on potassium-induced transmitter release in rat diaphragm muscles.

Effects of verapamil and manganese ion (Mn++) were examined on the rise in the frequency of miniature end-plate potential (m.e.p.p.) induced by hypertonic 10 mM potassium chloride (H10K) in rat diaphragm muscles. H10K consistently caused a 10-fold increase of the m.e.p.p. frequency and depolarized the membrane potential of muscle fiber by approximately 10 mV. The effect of H10K on the m.e.p.p. frequency disappeared in Ca++-free solutions. Verapamil (5 x 10(-5) M) and Mn++ (1 mM) consistently increased the m.e.p.p. frequency by factors of 3 and 5, respectively. The stimulatory effect of H10K on the m.e.p.p. frequency was abolished by Mn++ but was not affected by verapamil. These data suggest that the effect of verapamil on the motor nerve terminal is different from the effect on the cardiac muscle and on the vascular and intestinal smooth muscle.

Animals↗
PubMed1982

Repairability of drug-induced "wavy ribs" in rat offspring.

The development and repairability of "wavy ribs" were studied in offspring from dams of rat strain SD-JCL dosed with fenoterol, a beta-adrenoceptor stimulant. The incidence of "wavy ribs" was high at 1000 mg/kg/d. The critical administration period for the development of "wavy ribs" was from day 13 through 17 of gestation. Firstly, a delay of ossification in the middle of the ribs was seen on day 17. Thereafter, the middle part of the ribs began to curve and the curves were calcified until the end of gestation. Decreases of alkaline phosphatase and total protein were observed on day 20 in blood of fetuses showing "wavy ribs". The "wavy ribs" gradually disappeared until weaning. The effect of fenoterol could be partially blocked by the action of a beta-adrenoceptor blocker.

Abnormalities, Drug-Induced↗
PubMed1982

[The effect of levamisole on non-resected lung cancer--the results of randomized controlled study].

The effect of levamisole in the treatment of 61 non-resected lung cancer-26 squamous cell ca., 8 adenocarcinoma, 13 large cell ca. and 14 small cell ca- was studied by a randomized controlled trial. Levamisole was given at a daily dose of 150 mg per body weight for 3 consecutive days every 2 weeks. The main therapy, combining polychemotherapy and radiotherapy of standard dose or low dose, was given to both levamisole and control groups. The survival rate of the levamisole group was superior to that of the control group, with median survival time of 52 weeks in the former and 36 weeks in the latter, and with significant difference (p less than 0.05) during 46th to 52nd weeks. Comparing between the selected cases, the levamisole group was significantly superior (p less than 0.05) to the control group in all course examined, with median survival time of 64 weeks in the former and 36 weeks in the latter. Levamisole was more effective in the group of squamous and adenocarcinoma than large and small cell carcinoma. In the group where PPD reaction was negative at the time of initiation of the treatment levamisole was more effective than in the group of PPD positive, and also more effective in non-responders to the main therapy than responders. No side effect such as agranulocytosis was observed. Summarizing the present study, an immunotherapy employing levamisole combined with chemo-radiotherapy for non-resected lung cancer could be said to be effective in prolongation of survival time.

Adenocarcinoma↗