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Biomedical subjects

N Hirota

Publications and source records attributed to N Hirota.

At least 109 records · Page 6Linked to original sources
PubMed1983

Na+-driven flagellar motors of an alkalophilic Bacillus strain YN-1.

Flagellar motors of some alkalophilic Bacillus strains have been suggested to be powered by the electrochemical potential gradient of Na+, namely the (formula: see text) (Hirota, N., Kitada, M., and Imae, Y. (1981) FEBS Lett. 132, 278-280). In the present study, we quantitatively measured the (formula: see text) and motility of one of the strains, YN-1. Swimming speed of YN-1 cells increased linearly with a logarithmic increase of Na+ concentration in the medium up to 100 mM. The intracellular Na+ concentration and the membrane potential of the cell were about 30 mM and -170 mV, respectively, and stayed constant irrespective of Na+ concentration in the medium. Thus, the swimming speed changed as a function of the chemical potential difference of Na+ across the cell membrane. When the membrane potential of YN-1 cells was decreased by a combination of valinomycin and various concentrations of K+ in the medium, the swimming speed of the cells decreased linearly and reached zero at around -90 mV. Under the condition, the intracellular Na+ concentration stayed constant. Thus, the membrane potential was also a determinant of the swimming speed. Furthermore, the chemical potential of Na+ and the membrane potential were found to be equivalent as the energy source for motility. Therefore, it is concluded that the (formula: see text) is the energy source for the flagellar motors of YN-1 cells. Threshold value of the (formula: see text) for motility was about -100 mV.

Adenosine Triphosphate↗
PubMed1983

Effects of morphine on noxious stimuli-induced release of substance P from rabbit dorsal horn in vivo.

We investigated the effects of morphine on the noxious mechanical stimuli-induced release of immunoreactive substance P (iSP) from the rabbit dorsal horn in vivo. Systemic morphine in a dose of 10 mg/kg, but not 1 mg/kg, inhibited the iSP release induced by noxious stimuli, although both dosages inhibited the nociceptive responses of rabbits to the stimuli. The inhibitory effect of morphine (10 mg/kg) on the iSP release was partially or completely antagonized by the local application of naloxone or prazosin, respectively, to the dorsal horn. The local application of methysergide did not affect the morphine action. The inhibitory effect of morphine (10 mg/kg) on the iSP release was diminished in acute spinal animals. These results suggest that the inhibition of the evoked release of substance P participates only in the action of the larger dose of morphine, and that this inhibition of the substance P release may be mediated by opioid receptors and the noradrenergic system, but not the serotonergic system, in the spinal cord.

Animals↗
PubMed1983

Plasma LRH levels in chronic renal failure before and during haemodialysis.

Endogenous immunoreactive luteinizing hormone - releasing hormone (LRH) in plasma was determined in 6 male and 7 female patients with chronic renal failure before and during haemodialysis. Basal plasma LRH levels ranged from 5.8 to 23.0 pg/ml and, in 11 out of 13 patients, were above the levels seen in healthy subjects (less than 7 pg/ml for men and less than 8 pg/ml for women). This immunoreactivity was eluted iun identical fractions with synthetic LRH and plasma extracts from climacteric women on Sephadex G-25 chromatography, and the dilution gave a displacement curve parallel to the standard. Within 5 h of haemodialysis, these high LRH levels declined into the normal range. The concentrations of LH in plasma in these patients were also elevated, but those of testosterone in male patients were decreased. These results suggest 1) that elevated plasma LRH reflects decreased feedback inhibition by primary gonadal failure and might in turn be responsible at least in part for high concentrations of plasma LH in chronic renal failure, and 2) that plasma LRH is mainly not bound to plasma proteins.

Adult↗
PubMed1983

[Effect of adjuvant immunotherapy with Nocardia rubra cell-wall skeleton in lung cancer].

A randomized clinical trial of intrapleural Nocardia rubra cell-wall skeleton (N-CWS) followed by intradermal N-CWS was performed against lung cancer patients from November, 1977 to June 1981. Totally, 190 patients were entered into this trial. The N-CWS treatment was effective in terms of prolongation of remission duration against not only operable but also inoperable patients. However, significant improvement of survival rate was observed only in operable patients, especially curative+relatively curative resection-group (p less than 0.05). The mode of recurrence was classified as local recurrence and distant metastasis in the curative+relatively curative resection-group. The rates of distant metastasis were 34.1 and 17.6%, respectively, in the control and the N-CWS groups. The rate of local recurrence was 13.6% in the control group, however, no local recurrence was observed in the C-NWS group. These results indicate the clinical effectiveness of the N-CWS treatment especially in curatively resectable lung cancer. No serious side effect was experienced during this trial.

Adenocarcinoma↗
PubMed1982

Lack of effect of morphine and noxious stimuli on the MET-enkephalin content in the spinal dorsal horn and nucleus reticularis gigantocellularis of the rat.

The Met-enkephalin contents in the dorsal horn of the lumbar enlargement and the nucleus reticularis gigantocellularis of the medulla oblongata of the rat were measured, using a sensitive and specific radioimmunoassay for Met-enkephalin, and the effects of morphine and noxious stimuli on the Met-enkephalin contents in these regions were examined. In this radioimmunoassay, the IC50 and assayable limits for Met-enkephalin were 45 and 5 fmol/tube respectively, and the IC50 for Leuenkephalin was 0.56 nmol/tube (0.008% cross reactivity between Met-and Leu-enkephalins). The contents of Met-enkephalin-like immunoreactivity in the dorsal horn of the lumbar enlargement and the nucleus reticularis gigantocellularis were not altered by either subcutaneous injection of morphine or thermal (hot plate) and chemical (formalin injection) noxious stimuli applied to the hind-paws.

Animals↗
PubMed1982

Mercury oxidation in vitro by ferric compounds.

Among the ferric compounds studied, cytochrome C, methemoglobin, lactoperoxidase, ferritin and ferric ion, in addition to catalase, had the ability to oxidize metallic mercury in the presence of hydrogen peroxide. On the other hand, hematin, the active center of catalase, did not oxidize metallic mercury. The results are consistent with the increased oxidation and uptake of mercury in the liver by acatalasemia mice.

Animals↗
PubMed1982

Effect of dietary sodium ascorbate on 1,2-dimethylhydrazine- or methylnitrosourea-induced colon carcinogenesis in rats.

The effect of dietary sodium ascorbate (SA) on colon carcinogenesis evoked by 1,2-dimethylhydrazine (DMH) or N-methyl-N-nitrosourea (MNU) was studied in female F344 rats. Animals were fed diets containing 0, 0.25 and 1% of SA and given s.c. a single dose of 150 mg DMH/kg body wt., 10 weekly s.c. injections of 20 mg DMH/kg body wt. or intra-rectal administration of 2 mg MNU, twice a week for 2 weeks. The incidence of colon and kidney tumors was lower in rats fed the 0.25 or 1% SA and treated with a single dose of DMH than in the animals fed the diet without SA; however, the tumour incidences did not differ between the SA- and control diet-fed animals and treated with multiple doses of DMH or MNU.

1,2-Dimethylhydrazine↗
PubMed1982

Induction of gamma-glutamyltransferase-positive and nonspecific esterase-positive foci in rat liver by partial hepatectomy following single injection of N-nitrosodiethylamine.

The effect of partial hepatectomy (PH) on alteration of liver foci induced by N-nitrosodiethylamine (DENA) was studied in inbred F344 male rats. As early as 2 weeks after PH was performed 6 hours after an injection of 100 mg DENA/kg, gamma-glutamyltransferase-positive hepatocellular foci were induced, whereas DENA alone induced no foci until 12 weeks after PH. The focus counts of the group with PH performed 6 hours after an injection of 100 mg DENA/kg were consistently greater than those of a group with PH performed at 24 hours following DENA injection. At 3 and 6 weeks after PH was done at 12 weeks following treatment with 100 or 200 mg DENA/kg, the focus count was significantly increased compared with that in nonhepatectomized groups. The results indicate that increased liver cell proliferation resulting from PH enhances the conversion of persisting DNA damage to a permanent alteration in DNA. The effect at 12 weeks after exposure supports the concept that DNA damage in hepatocytes is highly persistent.

Animals↗
PubMed1982

Resistance to iron accumulation and presence of hepatitis B surface antigen in preneoplastic and neoplastic lesions in human hemochromatotic livers.

Two human cases of hepatocellular carcinoma combined with primary hemochromatosis and liver cirrhosis were studied with special reference to liver lesions displaying resistance to iron accumulation, and presence of hepatitis B surface antigen. Hepatocellular carcinomas, as well as small islands of hepatocytes within regenerative nodules, were free of the iron accumulation which otherwise occurred throughout the remainder of the hemochromatotic liver parenchyma. A positive reaction for hepatitis B surface antigen using the orcein staining method occurred randomly in iron-containing hepatocytes and in clusters of iron-containing hepatocytes cirrhotic nodules, but completely iron-free cells of foci and carcinomas were negative for orcein. Therefore, these iron-free foci are suggested to be precursors to the carcinoma.

Aged↗
PubMed1982

Ultrastructural abnormalities in carcinogen-induced hepatocellular altered foci identified by resistance to iron accumulation.

Hepatocellular altered foci were induced in rat liver by cycles of feeding of N-2-fluorenylacetamide and were distinguished by their resistance to iron accumulation following production of hepatic siderosis by dietary administration of 8-hydroxyquinoline and ferrous gluconate. The foci were readily identified by their iron exclusion in plastic-embedded sections stained for iron. Sections from iron-free regions processed for electron microscopy permitted ultrastructural study of cells in foci identified by reduced cytoplasmic ferritin. Altered foci of the eosinophilic type produced by cyclic feeding of carcinogen for 16 weeks were composed of both normal-appearing hepatocytes and others with ultrastructural abnormalities, including increased agranular reticulum with associated glycogen particles, decreased rough endoplasmic reticulum with reduced length of cisternae, degranulated rough vesicles, altered and displaced Golgi complexes, and abnormal bile canaliculi. At 12 and 24 weeks after cessation of carcinogen exposure, cells in persistent eosinophilic foci continued to display ultrastructural abnormalities. They possessed increased rough endoplasmic reticulum with rather regular cisternal arrangement and relatively increased smooth endoplasmic reticulum. Golgi complexes were abnormal. Bile canaliculi were abnormal and occasionally increased in number. Nuclei displayed prominent nucleoli. Cells in a basophilic focus were characterized by the presence of numerous free polyribosomes diffusely scattered throughout the cytoplasm, distended rough endoplasmic reticulum with loss of parallel-stack and hypertrophic dilated Golgi complexes, and prominent marginated nucleoli. The finding that persistent foci continued to display ultrastructural abnormalities, some of which changed or progressed in the absence of further carcinogen exposure, suggests that the persistent iron-excluding foci are a permanently altered population.

2-Acetylaminofluorene↗
PubMed1981

Use of lipophilic cation-permeable mutants for measurement of transmembrane electrical potential in metabolizing cells of Escherichia coli.

Some lipopolysaccharide-defective mutants of Escherichia coli showed, without ethylenediaminetetraacetic acid treatment, a quick and high uptake of lipophilic cations such as triphenylmethylphosphonium and tetraphenylphosphonium. The rate and amount of uptake were comparable to those of an ethylenediaminetetraacetic acid-treated wild type. Transmembrane electrical potential, which was calculated from the distribution of these lipophilic cations between the inside and outside of the mutant cells, was about -150 mV at pH 7.5 and showed a strong dependency on the external pH. One of the E. coli mutants, the acrA mutant, was found to be also permeable to dicyclohexylcarbodiimide, an H+-adenosine triphosphatase inhibitor, and 1-anilino-8-naphthalene sulfonate, a fluorescent dye. The acrA mutant was vigorously motile and highly sensitive to many bacteriophages and colicins. Thus, the acrA mutant is quite useful for the quantitative measurement of transmembrane electrical potential by lipophilic cations in intact and metabolizing cells especially in relation to motility and actions of colicins and bacteriophages.

Cell Membrane Permeability↗