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N Morishima

Publications and source records attributed to N Morishima.

At least 37 records · Page 2Linked to original sources
PubMed1996

Identification of intermediates in the conversion of cholesterol to pregnenolone with a reconstituted cytochrome p-450scc system: accumulation of the intermediate modulated by the adrenodoxin level.

Dihydroxycholesterol and pregnenolone were clearly detected on HPLC when 22R-hydroxycholesterol was incubated with a reconstituted P450scc system containing equimolar amounts of P450scc and adrenodoxin. The dihydroxycholesterol, which has been accepted to be an intermediate in the conversion of 22R-hydroxycholesterol to pregnenolone, accumulated when adrenodoxin was at a subsaturating level with respect to P450scc. The formation of the intermediate increased with increasing pH in the range of 7.2 to 8.1, and the ratio of the intermediate to the product, pregnenolone, increased with increasing pH. When the binding of P450scc to adrenodoxin was weakened by elevation of the ionic strength, the formation of the intermediate relative to the product increased. The apparent Km for dihydroxycholesterol at a subsaturating level of adrenodoxin was about 7 microM, in contrast to 4 microM at a saturating level of adrenodoxin, implying that the affinity of dihydroxycholesterol is lower at a subsaturating level of adrenodoxin than at a saturating one. These results suggest that a subsaturating level of adrenodoxin weakened the binding of dihydroxycholesterol to P450scc and thus the intermediate, dihydroxycholesterol, was released. An intermediate other than dihydroxycholesterol, obtained when cholesterol was used as the substrate, was identified as 22R-hydroxycholesterol by HPLC and mass spectroscopic analysis. The intermediate obtained when 22R-hydroxycholesterol was used as the substrate was identified as 20R,22R-dihydroxycholesterol by HPLC, mass, and 1H-NMR spectroscopic analyses. These results provide direct evidence that cholesterol is metabolized to pregnenolone by way of 22R-hydroxycholesterol and 20R,22R-dihydroxycholesterol by P45 scc.

Adrenodoxin↗
PubMed1996

Posterior routes of choroidal blood outflow in high myopia.

PURPOSE: A few reports in the ophthalmic literature have described choroidal blood outflow through posterior routes. Most of the patients reported were highly myopic; therefore, a correlation between such posterior routes and high myopia has been suspected. The authors examined highly myopic eyes using indocyanine green (ICG) videoangiography and investigated the prevalence and clinical significance of posterior routes in them. METHODS: The authors examined 255 highly myopic eyes (146 patients) using ICG videoangiography. All had refractive errors greater than--8.25 diopters (D). They also examined a control group consisting of 42 eyes (26 patients) that had refractive errors within +/- 3D. RESULTS: Of 255 highly myopic eyes, 61 (23.9%) had choroidal blood outflow through posterior routes. These routes were classified by type of vein according to its penetration site. One drained into the margin of the optic nerve head, and the other penetrated the sclera near the macula. However, only 1 of the 42 eyes (2.4%) in the control group showed choroidal outflow by a posterior route. The prevalence of posterior routes was significantly higher in the highly myopic eyes than in the control group (P < 0.05). CONCLUSION: Posterior routes of choroidal blood outflow were observed in nearly 25% of highly myopic eyes. These vessels appear to be one of the major routes of posterior choroidal outflow in highly myopic eyes.

Adolescent↗
PubMed1996

A case of uveitis associated with chronic active Epstein-Barr virus infection.

Ocular complications of chronic active Epstein-Barr virus infection (CAEBV) have rarely been reported. We describe a 7-year-old girl with CAEBV with associated uveitis. The patient was first observed to have recurrent fever and hepatosplenomegaly in August 1991. She presented with left facial nerve palsy in June 1993. Ocular examination showed right iridocyclitis. Both optic disks were swollen, and the retinal vessels were dilated. Antibody titers to EBV were markedly elevated. Treatment with topical steroids. systemic interleukin-2 and splenectomy dramatically relieved all her symptoms. including the ocular ones.

Antibodies, Viral↗
PubMed1996

[A case of sleep apnea syndrome due to a nasopharyngeal tumor].

Obstructive Sleep Apnea Syndrome (OSAS) is children is commonly caused by upper airway obstruction, such as that caused by adeno-tonsillar hypertrophy. We report a rare case of SAS due to a nasopharyngeal tumor. The patient was a 10-year-old boy who complained of snoring and sleep apnea. The tumor was found in the nasopharynx and mesopharyngeal space. We diagnosed this case as OSAS by overnight sleep study (Apnea Hypopnea Index: AHI = 19.67). The tumor was removed under general anesthesia. Histopathology revealed features of nasopharyngeal angiofibroma. After removal of the tumor, his symptoms resolved completely. A follow-up overnight sleep study confirmed resolution of OSAS. At the last follow up, conducted 17 months after the operation there were no signs of tumor recurrence.

Angiofibroma↗
PubMed1996

Effect of surgery on obstructive sleep apnea.

The statistical analysis of data obtained by monitoring pre- and post-operative conditions of patients treated for sleep apnea syndrome is reported. In the past 3 years, surgery was performed on 149 patients (55 children and 94 adults), who complained of snoring and symptoms related to the sleep apnea syndrome at Fujita Health University, The Second Hospital. Treatment for children was adeno-tonsillectomy. Treatment for adults was uvulo-palato-pharyngoplasty (UPPP), midline laser glossectomy (MLG) and/or nasal surgery. Apnea hypopnea index was defined as frequency of apnea hypopnea per hour. Pathological apnea (sleep apnea syndrome) was defined as apnea hypopnea (AHI) 10 in adults and AHI 5 in children. Marked improvement was defined as 75% reduction in AHI or a postoperative AHI below 10 in adults and 5 in children. Improvement was defined as 50-74% reduction of AHI. Slight improvement was defined as 25-49% reduction of AHI. No improvement was defined as less than 25% reduction of AHI. Of these 55 children, the AHI of 35 of them was above 5. Thirty cases (86%) showed marked improvement after treatment; 3 cases (8%) showed improvement; 1 case (3%) slight improvement and 1 case (3%) no improvement. Of these 94 adults, 40 cases (48%) showed marked improvement after treatment; 12 cases (14%) showed improvement; 14 cases (17%) slight improvement and 18 cases (21%) no improvement at all.

Adenoidectomy↗
PubMed1996

Diagnosis by dynamic MRI in sleep disordered breathing.

According to the obstructive site, different types of obstructive type sleep disordered breathing are classified as the soft palate type, palatine tonsil type, soft palate and depressed lingual root type, depression of the lingual root type, and epiglottis type. In this study, we conducted dynamic MRI examinations of the oral and pharyngeal and lingual root sites in patients with obstructive sleep disordered breathing, and studied MRI's usefulness as a diagnostic tool in the examination of such obstructive sites. In this paper, we present mainly the adult cases of patients with obstructive sleep disordered breathing which appeared to be caused by an enlarged palatine tonsil.

Humans↗
PubMed1995

A nuclear mutation defective in mitochondrial recombination in yeast.

Homologous recombination (crossing over and gene conversion) is generally essential for heritage and DNA repair, and occasionally causes DNA aberrations, in nuclei of eukaryotes. However, little is known about the roles of homologous recombination in the inheritance and stability of mitochondrial DNA which is continuously damaged by reactive oxygen species, by-products of respiration. Here, we report the first example of a nuclear recessive mutation which suggests an essential role for homologous recombination in the stable inheritance of mitochondrial DNA. For the detection of this class of mutants, we devised a novel procedure, 'mitochondrial crossing in haploid', which has enabled us to examine many mutant clones. Using this procedure, we examined mutants of Saccharomyces cerevisiae that showed an elevated UV induction of respiration-deficient mutations. We obtained a mutant that was defective in both the omega-intron homing and Endo.SceI-induced homologous gene conversion. We found that the mutant cells are temperature sensitive in the maintenance of mitochondrial DNA. A tetrad analysis indicated that elevated UV induction of respiration-deficient mutations, recombination deficiency and temperature sensitivity are all caused by a single nuclear mutation (mhr1) on chromosome XII. The pleiotropic characteristics of the mutant suggest an essential role for the MHR1 gene in DNA repair, recombination and the maintenance of DNA in mitochondria.

Base Sequence↗
PubMed1995

Multi-site-specific endonucleases and the initiation of homologous genetic recombination in yeast.

The notion that homologous recombination is a regulated biological process is not a familiar one. In yeasts, homologous recombination and most site-specific ones are initiated by site-specific double-stranded breaks that are introduced within cis-acting elements for the recombination. On the other hand, yeasts have a group of site-specific endonucleases (multi-site-specific endonucleases) that have a number of cleavage sites on each DNA. One of them, Endo.SceI of S. cerevisiae, was shown to introduce double-stranded breaks at a number of well-defined sites on the mitochondrial DNA in vivo. An Endo.SceI-induced double-stranded break was demonstrated to induce homologous recombination in mitochondria. Like the case of homologous recombination of nuclear chromosomes, the double-stranded break induces gene conversion of both genetic markers flanking and in the proximity of the cleavage site, and the cleaved DNA acts as a recipient of genetic information from the uncleaved partner DNA. The 70 kDa-heat-shock protein (HSP70)-subunit of Endo.SceI and a general role of the HSP70 in the regulation of protein-folding suggest the regulation of nucleolytic activity of Endo.SceI.

Base Sequence↗
PubMed1995

Cytochrome P-450scc-catalyzed production of progesterone from cholestenone.

Cholestenone, which is a 3-keto derivative of cholesterol, was incubated with cytochrome P-450SCC in a reconstituted hydroxylation system. Cholestenone was metabolized to progesterone with a turnover number of about 9 nmol/min/nmol P-450 in the presence of 0.01% Tween20. This value was about 70% of the maximal value for cholesterol. The final reaction product, progesterone, and three other minor reaction products, 20 alpha-hydroxycholest-4-en-3-one, 22R-hydroxycholest-4-en-3-one, 20,22-dihydroxycholest-4-en-3-one, were identified on the basis of its retention times on HPLC, thus suggesting them to be intermediates of side-chain cleavage of cholestenone. The results suggest that cholestenone is metabolized by two pathways, that is, the first hydroxylation occurs either at the C-20 position or at the C-22 position.

Animals↗
PubMed1995

The effects of modulation of the L-arginine-nitric oxide pathway on myocardial stunning following repetitive coronary occlusion in dogs.

In order to determine the role of nitric oxide (NO) in myocardial stunning, the effects of both augmenting and inhibiting NO production on contractile function, following repetitive coronary occlusions, were evaluated in anesthetized dogs. The effect of the experimental protocol on endothelial function was also assessed. The increases in coronary blood flow in response to acetylcholine and nitroglycerin at 30 and 60 min after reperfusion were similar to those before coronary occlusions. Therefore, loss in vasodilator reserve was not observed following the multiple coronary occlusions used in this study. NG-nitro-L-arginine methyl ester (L-NAME) elevated blood pressure slightly, but did not change left ventricular end-diastolic pressure, left ventricular maximum positive dp/dt, and coronary blood flow. Although the degree of systolic bulging and collateral circulation during coronary occlusions was comparable to the control group, contractile function after reperfusion was significantly worse in the presence of L-NAME than in the control. The recovery of contractile function was also considerably delayed with administration of L-arginine. This deleterious effect on contractile function was not observed with its enantiomer D-arginine. Differences in collateral blood flow determined with microspheres and hemodynamic variables did not account for the effects of L-arginine. These results suggest that endogenous NO is important in limiting myocardial stunning following repetitive coronary occlusion. However, NO may be cytotoxic when present in substantial excess.

Acetylcholine↗
PubMed1994

A mitochondrial homolog of bacterial GrpE interacts with mitochondrial hsp70 and is essential for viability.

Mitochondrial hsp70 (mhsp70) is located in the matrix and an essential component of the mitochondrial protein import system. To study the function of mhsp70 and to identify possible partner proteins we constructed a yeast strain in which all mhsp70 molecules carry a C-terminal hexa-histidine tag. The tagged mhsp70 appears to be functional in vivo. When an ATP depleted mitochondrial extract was incubated with a nickel-derivatized affinity resin, the resin bound not only mhsp70, but also a 23 kDa protein. This protein was dissociated from mhsp70 by ATP. ADP and GTP were much less effective in promoting dissociation whereas CTP and TTP were inactive. We cloned the gene encoding the 23 kDa protein. This gene, termed GRPE, encodes a 228 residue protein, whose sequence closely resembles that of the bacterial GrpE protein. Microsequencing the purified 23 kDa protein established it as the product of the yeast GRPE gene. Yeast GrpEp is made as a precursor that is cleaved upon import into isolated mitochondria. GrpEp is essential for viability. We suggest that this protein interacts with mhsp70 in a manner analogous to that of GrpE with DnaK of E.coli.

Adenosine Triphosphate↗
PubMed1993

Conjunctival malignant melanoma with xeroderma pigmentosum.

A 10-year-old male patient with xeroderma pigmentosum had a recurrent, pigmented, conjunctival tumor. Conjunctival malignant melanoma was diagnosed from the histopathological examination of the resected biopsy specimens. To our knowledge, this case of conjunctival malignant melanoma in a patient with xeroderma pigmentosum may be the second such report in the literature. We believe that malignant melanoma must be considered with squamous cell carcinoma in the differential diagnosis of conjunctival tumors in patients with xeroderma pigmentosum. Fontana-Masson and S-100 staining techniques helped diagnose this conjunctival malignant melanoma.

Child↗
PubMed1992

An endonuclease with multiple cutting sites, Endo.SceI, initiates genetic recombination at its cutting site in yeast mitochondria.

Endo.SceI is a mitochondrial sequence-specific endonuclease which has multiple cutting sites. In order to examine the possible role of Endo.SceI in homologous recombination, we analyzed the mode of recombination upon mating using antibiotic resistance markers on the mitochondrial genome. The segregation of a marker located very close to one of the Endo.SceI cutting sites showed a disparity (polarized segregation, i.e. gene conversion). This gene conversion depended on the presence of the functional Endo.SceI gene. In vivo cutting of mitochondrial DNA upon mating was detected at the cutting site in the antibiotic marker region, which also depended on the Endo.SceI activity. These results suggest that mitochondrial recombination is induced by cleavage of mitochondrial DNA by this sequence-specific endonuclease. This is the first demonstration that a sequence-specific endonuclease with multiple cutting sites induces genetic recombination.

Base Sequence↗
PubMed1991

Interaction of guanine-nucleotide-binding regulatory proteins with chemotactic peptide receptors in differentiated human leukemic HL-60 cells.

Human leukemic HL-60 cells were differentiated into neutrophil-like cells by treatment with dimethylsulfoxide (Me2SO) or N6,O2'-dibutyryladenosine 3',5'-phosphate (Bt2cAMP), and membrane fractions were prepared from the differentiated cells. Receptors for fMLF (fM,N-formylmethionine) and guanine-nucleotide-binding regulatory proteins (G proteins) serving as the substrate for pertussis toxin (islet-activating protein; IAP) were extracted from cell membranes then reconstituted into phospholipid vesicles. The binding of fMLF to the reconstituted vesicles (or the membranes) was determined with 10 nM [3H] fMLF. In both cases, high-affinity binding to vesicle preparations from the Me2SO- and Bt2cAMP-induced cells was abolished following treatment with IAP, suggesting that fMLF receptors were functionally coupled to IAP-sensitive G proteins in each of the two vesicle types. However, the high-affinity fMLF binding was much higher in vesicle preparations originating from Bt2cAMP-induced cells than in those from Me2SO-induced cells, although the amount of IAP-substrate G protein reconstituted into the each phospholipid vesicles preparation was not significantly different from the other. The G proteins of the two differentiated cells were both identified as inhibitory forms (Gi-2) based on their electrophoretic mobilities and immunoblot analyses. When purified Gi-2 from rat brain was reconstituted into the two IAP-treated vesicles, high-affinity fMLF binding was restored in a similar manner in both. IAP-substrate G proteins partially purified from the two differentiated HL-60 cells were also effective in restoring high-affinity fMLF binding to the IAP-treated vesicles. However, a significant difference was observed that the reconstituted binding was higher with the G-protein-rich fraction from Bt2cAMP-induced cells than with that from Me2SO-induced cells, with each of the two IAP-treated vesicle types. These results suggest that the different high-affinity binding of fMLF observed in the two differentiated HL-60 cells are due to a difference in the property of endogenous G proteins rather than fMLF receptors, though the two G proteins are indistinguishable from each other in terms of the subtype of G protein, Gi-2.

Bucladesine↗
PubMed1991

A maturase-like subunit of the sequence-specific endonuclease endo.SceI from yeast mitochondria.

Some yeast strains possess a sequence-specific endonuclease, Endo.SceI, which is a heterodimeric enzyme localized in mitochondria. The larger subunit (75 kDa) of Endo.SceI, encoded by a nuclear gene (ENS1), is transported from the cytosol into the mitochondria. In this study, we determined the partial amino acid sequence of the smaller subunit (50 kDa) of Endo.SceI. The determined sequence matched well the partial sequence deduced from a mitochondrial open reading frame (RF3). The RF3 locus is known to exhibit polymorphism since this reading frame in some yeast strains is supposed to encode a maturase-like protein, whereas in other strains, the frame is interrupted by GC clusters, which thus break the frame. Southern blot analysis of various yeast strains showed that the continuity of RF3 is correlated with the presence of Endo.SceI activity. These data indicate that the continuous RF3 sequence is a functional gene (ENS2) coding for the smaller subunit of Endo.SceI. The results of cytoduction, by which the continuous RF3 sequence was transferred into a yeast strain lacking mitochondrial DNA, confirmed this conclusion. This study suggests the involvement of Endo.SceI in genetic recombination of mitochondrial DNA.

Amino Acid Sequence↗