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Biomedical subjects

N Takimoto

Publications and source records attributed to N Takimoto.

At least 19 recordsLinked to original sources
PubMed1999

[Analysis of the long-term prognosis for conjunctival malignant melanomas in Japan].

PURPOSE: To investigate the long-term prognosis for primary conjunctival malignant melanomas in Japan. MATERIALS & METHODS: We conducted a survey of 61 cases which had been reported in a 38-year period (1959 to 1996). We gathered information regarding the survival of patients, the post-operative follow-up period, the causes of death, and recurrences. Answers were obtained segarding 51 cases (84%). Detailed progress was identified in 23 of these cases. The survival rates were calculated using the Kaplan-Meier method. RESULTS: The survival rates were 95.1% after 1 year, 72.9% after 3 years, and 53.4% after 5 years. These values are relatively low compared with those reported in Europe and the United States.

Adolescent↗
PubMed1998

pH-dependent growth retardation of Escherichia coli caused by overproduction of Na+/H+ antiporter.

The overproduction of Na+/H+ antiporter NhaA in Escherichia coli caused growth retardation. Quantities and the activity of the antiporter were studied for their causative roles in terms of this retardation. We constructed a series of nhaA-expression plasmids differing in their transcriptional and translational efficiencies. Low-level nhaA expression complemented the defect of an nhaA mutant and allowed the mutant to survive on a high-NaCl or high-LiCl medium. However, when the production of NhaA was strongly induced by the combination of a stronger promoter, an efficient translational initiation signal and a high copy number plasmid, the growth of the cells carrying the plasmid was severely retarded. This growth retardation correlated well with the amount of NhaA protein produced from the plasmids. Surprisingly, the growth retardation caused by overproduction of NhaA was enhanced more extensively at an alkaline pH than at a neutral pH, in which the antiporter activity was stimulated. However, these retardations were also observed for mutant NhaA antiporters without the activity. These results indicated that the growth retardation was due to an overproduction of the antiporter rather than its increased antiporter activity, and also affected by a pH-dependent change in NhaA, possibly its structural change.

Cell Division↗
PubMed1997

Synthesis and nematocidal activity of aralkyl- and aralkenylamides related to piperamide on second-stage larvae of Toxocara canis.

Seventy-nine aralkyl- and aralkenylamides related to piperamides were synthesized and their nematocidal activity against second-stage larvae of dog roundworm, Toxocara canis, was examined. The activity was greatly dependent on the alkyl chain length and the nature of the amine moiety, but was scarcely affected by the presence or absence of double bond(s) in the chain. The alkyl chain lengths which showed the strongest activity in a series of homologues were m = 11 for the pyrrolidine amides and m = 13 for the N-methylpiperazine amides. Although piperamides (3,4-methylenedioxyphenyl homologues) showed the strongest activity among the homologues tested, methoxy substituent(s) on the aromatic ring did not have much effect on the activity. However, conversion of the methoxy group to a hydroxy group greatly decreased the activity and shortened the chain length giving the strongest activity. Calculated log P values of non-phenolic aryl-piperamides fell in the range from 3.5 to 4.5, whereas those of hydroxyphenyl-piperamides were smaller, suggesting that different mechanisms are involved in the nematocidal activity of phenolic and non-phenolic compounds.

Amides↗
PubMed1993

Porous collagen sponge for esophageal replacement.

A new artificial esophagus with a bilayered structure made of porous collagen sponge and silicone was studied. The concept of this study was not to replace an esophageal defect permanently with prosthesis but to promote tissue regeneration by collagen. Five centimeters of cervical esophagus were replaced by this artificial esophagus in 19 adult mongrel dogs. Two weeks after implantation, the collagen sponge was replaced by autologous tissue and regeneration of the "neoesophagus" was observed in all animals. The inner surface of the neoesophagus was covered with mature mucosal epithelium similar to the intact esophagus 4-5 weeks after implantation. The replacement site was not complicated by infection, anastomotic leakage, or exuberant granulation tissue development on the luminal surface. In a long-term survival study, animals showed moderate-grade stenosis but could take normal feed orally and with no clinical problems observed.

Animals↗
PubMed1992

High-performance liquid chromatographic determination of cyanide in human red blood cells by pre-column fluorescence derivatization.

A method for the determination of cyanide in human red cells has been developed. Cyanide was extracted from red cells by adding water and methanol, and then derivatized with 2,3-naphthalene-dialdehyde and taurine to give a fluorescent product, which was determined by reversed-phase high-performance liquid chromatography with fluorescence detection. The recovery of cyanide from red cells was ca. 83%, and the limit of detection was 100 pmol/ml. The mean concentrations of red cell cyanide from ten smokers and from ten non-smokers were 705 and 466 pmol/ml, respectively. The method was also applicable to whole blood.

Chromatography, High Pressure Liquid↗
PubMed1989

Fluorometric assay of nicotinamide methyltransferase with a new substrate, 4-methylnicotinamide.

A fluorometric method for the assay of nicotinamide methyltransferase has been established using rat liver 9000 x g supernatant fluid as a model enzyme preparation. 1,4-Dimethylnicotinamide formed enzymatically from a new substrate, 4-methylnicotinamide, is quantified by means of its fluorescence reaction with 4-methoxybenzaldehyde in aqueous alkali. The lower limit of determination of 1,4-dimethylnicotinamide is 100 pmol in the enzymatic reaction mixture. The apparent Km values for 4-methylnicotinamide and for nicotinamide, which is a known substrate for this enzyme, were 0.19 and 0.13 mM, respectively, whereas the relative activity of 4-methylnicotinamide as a methyl acceptor was about 1.5 times the value of nicotinamide.

Animals↗
PubMed1987

Production of human thyroid-stimulating hormone in Chinese hamster ovary cells.

Human thyroid-stimulating hormone (hTSH) has been produced in Chinese hamster ovary (CHO) cells co-transformed with two plasmids: one carrying the alpha subunit cDNA with mouse dihydrofolate reductase gene and the other carrying hTSH beta subunit cDNA. Each cDNA was driven to expression under the control of SV40 early promoter. hTSH and its alpha subunit were secreted into culture media, and their secretion increased with exposure of the cells to increasing concentrations of methotrexate. Gel filtration analysis revealed that the molecular size of the hTSH was the same as that of natural hTSH. Furthermore, the CHO cell-produced hTSH elevated the cyclic AMP level in the rat thyroid cell line FRTL-5 in the same manner as natural hTSH does.

Animals↗
PubMed1987

Production of recombinant human pancreatic secretory trypsin inhibitor by Escherichia coli.

A synthetic gene for human pancreatic secretory trypsin inhibitor (PSTI) was fused to the coding sequence for the amino-terminal 135 amino acid residues of human interferon-gamma (IFN-gamma) by interposing a methionine codon sequence, and the resulting hybrid gene was efficiently expressed in Escherichia coli cells. Recombinant human PSTI (rHu-PSTI) was separated from the IFN-gamma/PSTI fused protein by cleavage at the methionine residue with cyanogen bromide. Finally, rHu-PSTI was purified by affinity chromatography on a bovine trypsin-CH-Sepharose 4B column. The amino acid composition, partial amino-terminal sequence, disulfide formation, human trypsin inhibitory activity, and immunoreactivity against rabbit anti-human PSTI serum of rHu-PSTI corresponded to those of the natural form.

Amino Acid Sequence↗
PubMed1987

Primary myxoma in the pituitary fossa: case report.

A case of primary myxoma in the pituitary fossa is described. The tumor presented as an intrasellar and suprasellar mass and was successfully removed during a transsphenoidal operation. It was verified as a myxoma by histopathological studies, and there was no evidence that it was a metastasis. This is thought to be the first report of this tumor occurring in the pituitary fossa.

Adult↗
PubMed1984

Trial of a new operative method for recurrent chronic subdural hematoma.

A new operative method for treating recurrent chronic subdural hematoma is presented. This method consists of complete obliteration of the subdural hematoma cavity and conversion of the hematoma cavity into epidural space. The procedure was carried out in three patients with recurrent chronic subdural hematoma, all of whom made a complete recovery.

Aged↗
PubMed1984

Therapeutic occlusion of the vertebral artery for unclippable vertebral aneurysm: relationship between site of occlusion and clinical outcome.

Six cases of unclippable vertebral aneurysms were treated by therapeutic occlusion of the proximal vertebral artery. In three cases, the vertebral artery was clipped proximal to the posterior inferior cerebellar artery (PICA), and all of these patients had a postoperative embolic complication or a fatal subarachnoid hemorrhage. In two cases, the vertebral artery was clipped distal to the PICA and in one case the PICA was absent and the vertebral artery was clipped proximal to the aneurysm. All three of these patients did well without any neurological deficit. Possible mechanisms of the complications are discussed, and the importance of not clipping the PICA is stressed.

Adult↗
PubMed1979

[Cervical internal carotid artery occlusion after recovery from suicidal hanging--a case report (author's transl)].

A case of internal carotid artery occlusion due to attempted hanging was reported. This 51-year-old man, who failed in suicidal hanging, remained in right hemiplegia and total aphasia. Left carotid arteriogram revealed complete occlusion of the internal carotid artery approximately 1 cm distal to its origin. Surgical exposure of the internal carotid artery was performed 4 weeks after the attempted hanging. The occlusive portion was percutaneously injured by ligature, whereby there was a horizontal breach of intima, media and adventitia at the level of the ligature. The damaged arterial wall was resected, and a reconstructive vascular surgery in the neck was performed. But postoperative arteriogram showed an unsatisfactory result. Pathogenesis of traumatic involvements of the internal carotid artery was discussed with literature. Also it was discussed that internal carotid artery occlusion was a very important factor causing death in suicidal hanging.

Carotid Artery Thrombosis↗
PubMed1978

Giant cell tumor of the skull.

A 23 year-old female had a giant cell tumor originating in the right temporal bone. A diagnosis was maed by biopsy. Microscopically it was sarcomatous in part. Two courses of radiation therapy, each total dose being 6000 rads and 3000 rads in air, were employed with good subjective response for a short duration. However, the tumor involving the petrous bone and the mastoid process extended, invading the epipharynx and the clivus. The patient died one year after onset.

Adult↗