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Biomedical subjects

N Ichikawa

Publications and source records attributed to N Ichikawa.

At least 127 records · Page 7Linked to original sources
PubMed1990

Isolation of a gene for a regulatory 15-kDa subunit of mitochondrial F1F0-ATPase and construction of mutant yeast lacking the protein.

A gene coding for yeast 15-kDa protein, a regulatory factor of mitochondrial F1F0-ATPase, was isolated. The cloned gene was disrupted in vitro and mutant strains that did not contain the 15-kDa protein were constructed by transformation of yeast cells with the disrupted gene. The ATP-synthesizing activity of the mutant mitochondria was the same as that of wild-type cells, suggesting that the 15-kDa protein is not required for mitochondrial oxidative phosphorylation. Collapse of the membrane potential induced ATP-hydrolyzing activity of F1F0-ATPase of the mutant mitochondria but not of normal mitochondria. Activation of the enzyme was also observed during incubation of submitochondrial particles from mutant cells, but not of those from wild-type cells. Thus, it is inferred that the 15-kDa protein supports the action of an intrinsic ATPase inhibitor of the ATP-hydrolyzing activity of the enzyme upon de-energization of mitochondrial membranes.

Amino Acid Sequence↗
PubMed1990

Activation of ATP hydrolysis by an uncoupler in mutant mitochondria lacking an intrinsic ATPase inhibitor in yeast.

An intrinsic ATPase inhibitor and 9-kDa protein are regulatory factors of mitochondrial ATP synthase in Saccharomyces cerevisiae. A gene encoding the ATPase inhibitor was isolated from a yeast genomic library with synthetic oligonucleotides as hybridization probes and was sequenced. The deduced amino acid sequence showed that the precursor protein contains an amino-terminal presequence of 22 amino acid residues. Mutant strains that did not contain the inhibitor and/or the 9-kDa protein were constructed by transformation of cells with their in vitro disrupted genes. The disruption of the chromosomal copy in recombinant cells was verified by Southern blot analysis, and the absence of the proteins in the mutant cells was confirmed by Western blot analysis. All the mutants could grow on a nonfermentable carbon source and the oxidative phosphorylation activities of their isolated mitochondria were the same as that of normal mitochondria. However, an uncoupler, carbonylcyanide-m-chlorophenylhydrazone, induced marked ATP hydrolysis in the inhibitor-deficient mitochondria, but not in normal mitochondria. These observations suggest that the ATPase inhibitor inhibits ATP hydrolysis by F1F0-ATPase only when the membrane potential is lost.

Adenosine Triphosphate↗
PubMed1990

Enhanced resolution of DNA restriction fragments: a procedure by two-dimensional electrophoresis and double-labeling.

A probe-free method was developed to detect DNA rearrangement in bacteria based on the electrophoretic separation of twice-digested restriction fragments of genomic DNA into a two-dimensional (2-D) pattern. The first restriction enzyme digestion was done in solution, followed by electrophoresis of the restriction fragments in one dimension. A second restriction enzyme digestion was carried out in situ in the gel, followed by electrophoresis in a second dimension perpendicular to the first electrophoresis. The 2-D pattern provides for the resolution of 300-400 spots, which are defined and indexed by an "x,y" coordinate system with size markers. This approach has greatly increased the resolution power over conventional one-dimensional (1-D) electrophoresis. To study DNA rearrangement, a 2-D pattern from a test strain was compared with the 2-D pattern from a reference strain. After the first digestion, genomic DNA fragments from the test strain were labeled with 35S, while those from the reference strain were labeled with 35P. This was done to utilize the difference in the energy emission of 35S and 32P isotopes for autoradiography when two x-ray films were exposed simultaneously on top of the gel after the 2-D electrophoresis. The irradiation from the decay of 35S exposed only the lower film, whereas the irradiation from the decay of 32P exposed both the lower and upper films. Different DNA fragments existed in the test DNA compared with the reference DNA can be identified unambiguously by the differential two 2-D patterns produced on two films upon exposure to the 35S and 32P fragments in the same gel. An appropriate photographic procedure further simplified the process, allowing only the difference in DNA fragments between these two patterns to be shown in the map. We have utilized the difference map obtained from Escherichia coli strains HB101 and HB101 (lambda) genomic DNA to show the incorporation of one copy of phage lambda DNA without the use of a lambda DNA probe. This is the same test system that was used previously.

Bacteriophage lambda↗
PubMed1990

A possible reduction in the renal clearance of ciprofloxacin by fenbufen in rats.

The change in plasma concentration-time profile, serum protein binding and renal and biliary clearances of ciprofloxacin caused by coadministration of fenbufen has been studied in rats administered an intravenous dose of ciprofloxacin (5 mg kg-1) alone or with fenbufen (10 mg kg-1). Coadministered fenbufen significantly prolonged the plasma elimination half-life of ciprofloxacin from 40.5 to 57.6 min and tended to reduce the total body clearance of this quinolone by about 20%. The extent of ciprofloxacin binding to rat serum protein was not affected by fenbufen, nor did it affect the biliary clearance of the quinolone. However, fenbufen tended to reduce renal clearance and significantly decreased the cumulative renal excretion of the quinolone during at least the first 3 h after drug administration. These results suggest a possible reduction of ciprofloxacin clearance owing to inhibition of renal excretion by fenbufen.

Animals↗
PubMed1990

A minor possibility of pharmacokinetic interaction between enoxacin and fenbufen in rats.

In order to clarify the possibility of pharmacokinetic interaction between quinolone and fenbufen, the plasma concentration-time profiles and serum protein binding of enoxacin, fenbufen and its active metabolite, felbinac, were investigated in rats. The rats were administered an intravenous dose of enoxacin (5 mg/kg) and fenbufen (10 mg/kg) alone or concomitantly. Coadministration with fenbufen tended to prolong the plasma elimination half-life of enoxacin by about 20%, whereas it showed no effect on the area under plasma concentration-time curve, total body clearance or distribution volume of enoxacin. The extent of enoxacin binding to rat serum tended to be slightly reduced by fenbufen in vivo and in vitro. Plasma concentration-time curves, pharmacokinetic parameters and serum protein binding of fenbufen and felbinac were not affected at all by the coadministration with enoxacin. These aspects suggest that there may be only a minor possibility of the pharmacokinetic interaction between enoxacin and fenbufen.

Animals↗
PubMed1990

High-performance liquid chromatographic determination of ciprofloxacin in rat brain and cerebrospinal fluid.

A novel high-performance liquid chromatographic method for the fluorometric determination of a newer quinolone, ciprofloxacin (CPFX), in rat brain and cerebrospinal fluid (CSF) was developed. CPFX in brain homogenate was extracted and injected onto a reversed-phase column without fluorescence derivatization. CSF was directly analyzed without the extraction procedure. Calibration curves were linear over the concentration ranges of 10 to 500 ng/g for brain and 5 to 500 ng/ml for CSF. The recoveries of CPFX added to brain were more than 97% with a coefficient of variation of less than 4%. The present method was sensitive and reliable enough to be utilized for detailed pharmacokinetic studies of CPFX in rat brain and CSF.

Animals↗
PubMed1989

Absence of pharmacokinetic interaction between ofloxacin and fenbufen in rats.

The possible pharmacokinetic interaction between a new quinolone and fenbufen was investigated by comparing the plasma concentration-time profiles and serum protein binding of ofloxacin, fenbufen and its active metabolite, felbinac, in rats. The rats were administered intravenous doses of ofloxacin (5 mg kg-1), fenbufen (10 mg kg-1) alone or concomitantly. The plasma elimination half-lives were about 55 min in both groups. A slight elevation of plasma concentration of ofloxacin and a small decrease of its total body clearance were observed after its coadministration with fenbufen. The extent of ofloxacin binding to rat serum tended to be slightly reduced by fenbufen which coexisted at relatively high concentrations. Plasma concentration-time curves, pharmacokinetic parameters and serum protein binding of fenbufen and felbinac were not affected by the coadministration with ofloxacin. These results suggest that any substantive pharmacokinetic interaction may be unlikely after the concomitant administration of ofloxacin and fenbufen.

Animals↗
PubMed1989

High-performance liquid chromatographic procedure for the simultaneous determination of norfloxacin, fenbufen and felbinac in rat plasma.

A high-performance liquid chromatographic method for the simultaneous determination of norfloxacin, fenbufen and felbinac extracted from 50 microliters of rat plasma is described. Chromatography was performed on a reversed-phase column with ultraviolet detection. By the present method, quantitative and reproducible determinations were possible for norfloxacin, fenbufen and felbinac over the concentration ranges of 0.2-20, 0.2-120 and 0.4-40 micrograms/ml, respectively. The recoveries of norfloxacin, fenbufen and felbinac added to plasma were nearly 100% with a coefficient of variation of less than 8.0%. This method was found to be applicable to pharmacokinetic studies of each drug after the concomitant administration of norfloxacin and fenbufen.

Animals↗
PubMed1989

[Two cases of small intrahepatic arterial aneurysm].

Two cases with intrahepatic aneurysms were experienced. One was associated with hemobilia, the other was found incidentally. These aneurysms had angiographic appearance of pseudo-aneurysm, and occurred in peripheral branches of hepatic arteries, that are rare location for aneurysm formation. Causative factor was demonstrated in neither of the cases.

Aged↗
PubMed1988

Simultaneous determination of ofloxacin, fenbufen and felbinac in rat plasma by high-performance liquid chromatography.

Ofloxacin, fenbufen and its active metabolite, felbinac, were simultaneously extracted from 50 microliters of rat plasma and analysed by high-performance liquid chromatography on a reversed-phase column. Quantitative and reproducible determinations were possible for ofloxacin, fenbufen and felbinac over the concentration ranges 0.15-40, 0.3-80 and 0.45-45 micrograms/ml, respectively. The detection limits for all the drugs were lower than those reported previously. The recovery of ofloxacin, fenbufen and felbinac added to plasma was nearly 100% with a coefficient of variation of less than 3.0%. This method was found to be applicable to pharmacokinetic studies of each drug after the concomitant administration of ofloxacin and fenbufen.

Animals↗
PubMed1986

Study on monoamine metabolite contents of cerebrospinal fluid in patients with neurodegenerative diseases.

Main monoamine metabolities of cerebrospinal fluid (CSF), i.e., 3-methoxy-4-hydroxyphenylglycol (MHPG), 5-hydroxyindoleacetic acid (5-HIAA), homovanillic acid (HVA), were measured in 74 patients with neurodegenerative diseases, in 30 normal control subjects and in 16 diseased control subjects without neurodegenerative diseases. The symptoms of patients were scored according to an original scale. It was suggested by statistical study including multiple regression analysis that there might be significant relationship between CSF-MHPG level and extrapyramidal symptoms, or autonomic symptoms, and between CSF-5-HIAA level and extrapyramidal, or cerebellar symptoms, and between CSF-HVA level and extrapyramidal, pyramidal, or cerebellar symptoms. It was also suggested that the severer the symptoms of patients with Parkinson's disease, Shy-Drager syndrome, or olivopontocerebellar atrophy became, the lower the levels of monoamine metabolities of CSF became. The activity of peripheral catecholamine metabolism might influence the CSF-MHPG level because of the significant positive correlations between CSF-MHPG level and urine noradrenaline or vanillylmandellic acid level. The level of MHPG was high in patients with severe amyotrophic lateral sclerosis or hereditary spinocerebellar degeneration possibly because of stress with respiratory dysfunction.

Adult↗
PubMed1985

Studies of hydroxypropylmethylcellulose acetate succinate on fertility in rats.

A fertility study was carried out in Slc: SD rats orally administered Hydroxypropylmethylcellulose acetate succinate (HPMCAS), a useful pharmaceutical excipient, at dose levels of 625, 1,250 and 2,500 mg/kg/day. Male rats were treated with HPMCAS from 60 days before pairing until the completion of mating. Female rats received HPMCAS for 22 days, from 14 days prior to mating up to Day 7 of gestation. All pregnant females were sacrificed on Day 21 of gestation and all fetuses were examined for abnormalities. No abnormal signs were seen in mating or fertility in the rat treated with HPMCAS. No external, internal and skeletal anomalies attributable to HPMCAS were observed in the fetuses. It was concluded that HPMCAS had no harmful effect on mating, fertilization, implantation, or embryonic development.

Administration, Oral↗
PubMed1985

Teratological studies of hydroxypropylmethylcellulose acetate succinate in rats.

A teratogenicity study was carried out in S1c: SD rats orally administered Hydroxypropylmethylcellulose acetate succinate (HPMCAS), a useful pharmaceutical excipient, at dose levels of 625, 1,250 and 2,500 mg/kg/day for a period of 11 days from day 7 to day 17 of gestation. Two-thirds of the pregnant females in each group were sacrificed on Day 21 of gestation and their fetuses were examined. The remaining dams were allowed to litter naturally, and the postnatal development of the offsprings was observed. The incidences of external, internal, and skeletal anomalies were not significantly increased in the fetuses of any treated groups. HPMCAS caused no effects on parturition, lactation, postnatal growth and reproductive ability of the male and female offspring.

Abnormalities, Drug-Induced↗