Biomedical subjects
Publications and source records attributed to T Kurihara.
Evidence is presented that expression of the two myelin-associated glycoprotein mRNAs is developmentally regulated in mouse brain. In quaking mouse, the mRNA without a 45-nucleotide exon portion was scarcely expressed throughout development. We conclude that the mechanism of splicing out the 45-nucleotide exon portion is lacking in quaking mouse.
A cDNA of 1762 base pairs was obtained from a cDNA library of human brain by immunoscreening, and the nucleotide sequence of the cDNA was determined. The complete amino acid sequence of human 2',3'-cyclic-nucleotide 3'-phosphodiesterase was deduced from the nucleotide sequence of the cDNA. Human enzyme was found to contain 401 amino acids including initiation methionine and have a molecular weight of 45,098. RNA blot hybridization revealed a single mRNA band at the position of about 3000 bases. DNA blot hybridization suggested that a single-copy 2',3'-cyclic-nucleotide 3'-phosphodiesterase gene exists per haploid genome.
Two kinds of 3-ketoacyl-CoA thiolases were found in the peroxisomes of Candida tropicalis cells grown on n-alkanes (C10-C13). One was a typical acetoacetyl-CoA thiolase specific only to acetoacetyl-CoA, while another was 3-ketoacyl-CoA thiolase showing high activities on the longer chain substrates. A high level of the latter thiolase activity in alkane-grown cells was similar to that of other enzymes constituting the fatty acid beta-oxidation system in yeast peroxisomes. These facts suggest that the complete degradation of fatty acids to acetyl-CoA is carried out in yeast peroxisomes by the cooperative contribution of acetoacetyl-CoA thiolase and 3-ketoacyl-CoA thiolase.
A 29-year-old single woman had recurrent stroke-like episodes. She developed loss of consciousness, myoclonic seizures, and lactic acidosis. She died at the age of 30. A muscle biopsy study revealed mitochondrial myopathy, and the postmortem biochemical analysis demonstrated decreased cytochrome c oxidase activity in the skeletal muscles by 20% of normal control. The brain had multiple ischemic lesions in the cerebral cortex without major vascular occlusions. We present this case as an autopsy case of mitochondrial myopathy, encephalopathy, lactic acidosis, and stroke-like episodes (MELAS) with a partial deficiency of cytochrome c oxidase. The analytical electron microscopic study of the calcified small vessels in the globus pallidus revealed increased calcium, phosphorus and iron. No accumulation of chromium, nickel or zinc was noted in this case, which was different from the previously reported cases of basal ganglia calcification.
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Flow of Latex suspension with high concentration between plate glasses was observed through an optical microscope. Size of aggregates of Latex particles was estimated by measuring area of a region without particles behind an obstacle in the flow region (this technique had been developed by one of the authors). At the same time, viscosity and elasticity of the suspension were measured by a cone-plate viscometer, and relations between the aggregate size and these properties were obtained. A simple model based on the Stokes law of resistance and the Maxwell model for viscoelastic materials is proposed to explain these relations. The theoretical results agree with the present experiment.
A 61-year-old woman with left advanced breast cancer (T3a, N2, M0, Stage IIIa) underwent preoperative chemotherapy. The regimen consisted of etoposide 70 mg/m2 (day 4, 5, 6 i.v.), adriamycin 20 mg/m2 (day 1, 7 i.v.) and cis-platinum 40 mg/m2 (day 2, 8 i.v.). By the third week of administration, the size of the breast tumor reduced markedly, with the rate of 97%, resulting in partial response. Following preoperative combination-chemotherapy, a left extended radical mastectomy was performed. Histological findings of the resected specimen showed sufficient effects of chemotherapy; degeneration of tumor cells, infiltration of histiocytes and fibrosis of stroma. After operation, chemotherapy with the same dosage and sequential irradiation were undergone. As the side effect of this chemotherapy, slight nausea, vomiting and leucocytopenia were observed. The result of this case suggested that combination-chemotherapy with etoposide, adriamycin and cisplatinum was an effective chemotherapy for advanced breast cancer.
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A cDNA clone for the mRNA of bovine DARPP-32 (dopamine- and adenosine 3',5'-monophosphate-regulated phosphoprotein, Mr = 32,000) was isolated from a modified Okayama-Berg plasmid library. Transformed Escherichia coli colonies were screened by in situ colony hybridization with 2 different oligonucleotide probes corresponding to a region unusually rich in glutamate within the protein. Three positive clones were isolated and shown to encode DARPP-32 by an in situ immunoblot assay of their fusion protein products with beta-galactosidase. The results of the sequence analysis of the longest cDNA clone, pTKD7 (1771 nucleotides), revealed a 606-nucleotide-long coding region, in exact agreement with the bovine DARPP-32 amino acid sequence (Williams et al., 1986). Southern blot analysis of total bovine genomic DNA showed that there is a single gene coding for DARPP-32. Northern blot analysis of caudate nucleus RNA using antisense RNA derived from the clone pTKD7 demonstrated the existence of 2 abundant mRNA species, corresponding to 1.8 and 1.65 kilobase in length. The high concentration of DARPP-32 mRNAs in the caudate nucleus is in agreement with the known distribution of this protein.
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2',3'-Cyclic-nucleotide 3'-phosphodiesterase (EC 3.1.4.37) has been widely used as a marker for myelin-oligodendrocytes in the central nervous system. Evidence has been provided that the enzyme is identical with one of the Wolfgram proteins of central nervous system myelin. The amino acid sequence of bovine 2',3'-cyclic-nucleotide 3'-phosphodiesterase was determined by both protein and cDNA sequence analyses. Protein sequence analysis was done on bovine elastase 2',3'-cyclic-nucleotide 3'-phosphodiesterase, a low molecular weight enzyme obtained by solubilization with pancreatic elastase (EC 3.4.21.36) (Nishizawa, Y., Kurihara, T., and Takahashi, Y. (1980) Biochem. J. 191, 71-82; Kurihara, T., Nishizawa, Y., Takahashi, Y., and Odani, S. (1981) Biochem. J. 195, 153-157). Based on the carboxyl-terminal sequence of bovine elastase 2',3'-cyclic-nucleotide 3'-phosphodiesterase, synthetic oligodeoxyribonucleotides were prepared and used as probes for screening a cDNA library of bovine brain. A cDNA of 2305 base pairs was obtained and sequenced, and the complete amino acid sequence of bovine 2',3'-cyclic-nucleotide 3'-phosphodiesterase was deduced. Bovine 2',3'-cyclic-nucleotide 3'-phosphodiesterase deduced contains 400 amino acids including initiation methionine and has a molecular weight of 44,850. Bovine elastase 2',3'-cyclic-nucleotide 3'-phosphodiesterase corresponds to the 236 amino acids of bovine 2',3'-cyclic-nucleotide 3'-phosphodiesterase. RNA blot analysis revealed a single-species mRNA of about 2600 bases.
Familial amyloidotic polyneuropathy (FAP) has been biochemically and genetically proven to be an inherited molecular disorder of transthyretin. (The term transthyretin has been suggested by the Nomenclature Committee of the international Union of Biochemistry and the International Union of Pure and Applied Chemistry for the protein that has heretofore been called prealbumin.) We have experienced three cases that included typical clinical, electrophysiologic, and neuropathologic manifestations of FAP, and yet no known family history of the disorder. The patients and members of their families were studied by radioimmunoassay for a variant transthyretin with a methionine-for-valine substitution at position 30. All three patients had the variant transthyretin in the serum, at concentrations of 54.5, 87.9, and 105.9 mg/L (5.45, 8.79, and 10.59 mg/dL). Although parents and siblings had neither neurologic nor electromyographic evidence of FAP, some of these family members had serum concentrations of variant transthyretin as high as those of the propositi. It was from these asymptomatic parents that the "nonfamilial" patients inherited the gene for FAP. Further study is needed to define the mechanisms retarding or preventing, as well as those promoting, the clinical development of FAP when the variant transthyretin is present in the serum at a high level.
Type I familial amyloidotic polyneuropathy is an autosomal dominant, inherited systemic amyloidosis characterized initially by dissociated sensory disturbance and autonomic dysfunction. The amyloid fibril protein seen in patients of Portuguese, Japanese, and Swedish descent in the U.S. mainly consists of a variant form of transthyretin (also called prealbumin) with the substitution of methionine for valine at position 30. Methods have been developed to detect this variant transthyretin in the serum, and to detect a base change in a mutated transthyretin gene. The biochemical and genetic abnormalities in transthyretin are completely linked to the clinical diagnosis of type I familial amyloidotic polyneuropathy. These diagnostic methods may allow early diagnosis and genetic counseling to avoid transmission of this intractable disorder to the next generation.
Structurally abnormal transthyretin is a precursor protein of amyloid fibrils in type I familial amyloidotic polyneuropathy (FAP). This variant transthyretin has an amino acid substitution of methionine for valine at position 30. The purpose of this study was to clarify whether this variant transthyretin also circulates in the cerebrospinal fluid (CSF) of patients with type I FAP. CSF transthyretin of the patients was purified and its primary structure determined. Sequence determination indicated that transthyretin consisted of a mixture of normal and variant transthyretin. Variant transthyretin was present in the CSF of all 5 Japanese FAP patients studied. The CSF concentration of variant transthyretin was high (0.72 +/- 0.15 mg/dl, mean +/- S.D.), suggesting that variant transthyretin is synthesized in the choroid plexus. Variant transthyretin was not present in any of 20 controls. The CSF concentration of total transthyretin in FAP patients was 1.74 +/- 0.42 mg/dl, which was not significantly different from controls.
The relationships between the cytotoxic effect of ultraviolet light and the UV-induced sister-chromatid exchanges (SCEs) were compared among fibroblast cell strains from two unrelated Bloom's syndrome (BS) patients, one xeroderma pigmentosum (XP) patient belonging to complementation group A and two unrelated normal controls. The "net" induced SCEs as a function of UV fluence, obtained by subtracting spontaneous SCEs from observed SCEs, were much higher in both BS cells and XP group A cells than in normal cells. The relative efficiency of induced SCE, defined as the "net" induced SCEs as a function of surviving fraction after UV irradiation, was higher in BS cells than in normal and XP cells, and there was essentially no difference between XP and normal cells. These results imply that in addition to the extremely high frequency of spontaneous SCEs, the increased efficiency in UV induction of SCEs may reflect the intrinsic defect(s) in BS cells.