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Biomedical subjects

T Kurihara

Publications and source records attributed to T Kurihara.

At least 307 records · Page 17Linked to original sources
PubMed1987

Hypersensitivity of Bloom's syndrome fibroblasts to N-ethyl-N-nitrosourea.

Fibroblast cells from two Japanese patients with Bloom's syndrome (BS) and normal donors were studied for the inactivation of colony-forming ability and the induction of sister-chromatid exchanges (SCEs) after N-ethyl-N-nitrosourea (ENU) treatment. The reduction of ENU-induced SCEs as a function of post-treatment incubation time was also compared between BS and normal fibroblasts. BS cells were approximately 4 times more sensitive than normal cells to the lethal effect of ENU and remarkably hypersensitive to the SCE induction by ENU. The post-treatment incubation of ENU-treated normal cells in the fresh medium resulted in a time-dependent decrease of the SCE level until 6 h after which time the SCE level remained the plateau of about 50% of the initial level. In contrast, the ENU-induced SCEs in BS cells decreased much more slowly with post-treatment incubation time and its half life was 24 h. These results collectively support the view that BS cells may be defective in the rapid repair of certain type(s) of DNA damages induced by ENU.

Bloom Syndrome↗
PubMed1987

Differential hypersensitivity of xeroderma pigmentosum lymphoblastoid cell lines to ultraviolet light mutagenesis.

Survival and mutation after u.v. light irradiation were examined in four human lymphoblastoid cell lines; one cell line with normal excision-repair capacity (HH4), two excision-repair-deficient xeroderma pigmentosum (XP) cell lines from patient XP3BE (complementation group C) and XP7NI (group A), and one cell line from an XP heterozygote (XPF7NI, father of XP7NI). Relative to HH4 and XPF7NI, both XP3BE and XP7NI were more sensitive to the cytotoxic effect of u.v. by virtue of a diminished shoulder and a steeper slope in the survival curve determined by growth curve extrapolations. The mutagenesis for 6-thioguanine resistance (TGr) was measured by the limiting dilution technique using 96 well microtiter plates. Even at non-cytotoxic fluences, u.v. light induced TGr mutations in HH4 and XPF7NI with no apparent threshold, and the mutagenic response of XPF7NI was no different than that of HH4. Both XP cell lines were more sensitive than normal cells to u.v.-induced mutation. However, XP7NI cells were extremely hypermutable by u.v.; i.e. 3.3 J/m2 induced an approximately 500-fold increase of mutant fraction with the background of 2 X 10(-6). XP7NI cells remained much more mutable by u.v. even when plotted against survival, whereas the mutant fractions for XP3BE and HH4 followed the same line. These results imply that the mechanism of u.v.-induced mutation in XP7NI cells may intrinsically be different from that in XP3BE, XP heterozygote or normal cells, or that potentially mutagenic lesions are repaired much less efficiently in XP7NI cells than are potentially lethal lesions, as compared with XP3BE, XPF7NI and HH4 cells.

Cell Line↗
PubMed1987

DNA synthesis in Bloom's syndrome fibroblasts.

The relationship between relative rates of DNA synthesis and DNA content in Bloom's syndrome fibroblasts (BS cells) was investigated by flow cytometry. The cells were pulse labelled with 5-bromo-2'-deoxyuridine (BrdU). The BrdU content and cellular DNA content of individual BS cells were simultaneously measured by flow cytometry in which the cells were double-stained by a FITC-conjugated anti BrdU monoclonal antibody (mAb) for the BrdU content (green) and by PI (propidium iodide) (red) for total DNA content. Their red fluorescence histograms were analysed by a microcomputer to evaluate the cell fractions of each S compartment. The BrdU uptake in the early S phase of BS cells was lower than that of normal cells (fibroblasts from skin of a normal human), whereas the uptake in the middle and late S phase was essentially the same as that of normal cells. The early S phase in BS cells accounted for over 50% of the S phase cells. These findings suggest that, in comparison with normal cells, the rate of DNA synthesis in the early S phase of BS cells is lower, but is identical to controls in the middle and late S phases.

Bloom Syndrome↗
PubMed1987

Biochemical characterization of familial amyloidotic polyneuropathy in various districts of Japan.

The purpose of this study is to disclose the molecular basis of type I familial amyloidotic polyneuropathy (FAP) in Japan. Amyloid fibril protein of type I FAP consists of a variant transthyretin (also called prealbumin) with one amino acid substitution of methionine-for-valine at position 30. This variant transthyretin is present in the serum as a precursor protein of amyloid. A radioimmunoassay (RIA) has been established to detect the variant transthyretin. All the 94 patients with FAP who originate from various districts in Japan have the variant transthyretin, but any one of 78 healthy adults of families with FAP do not have it. Half of the symptom-free children of FAP patients have the variant transthyretin even before clinical manifestations appear. The RIA is widely applicable for early diagnosis. The methionine-for-valine substitution is due to a base change from guanine to adenine at the first letter of the valine codon at position 30. Type I FAP in Japan is considered to be a molecular disorder of transthyretin. Since the age of onset ranges from twenties to forties, genetic counseling is recommended to prevent the transmission of this intractable disorder to the next generation.

Adolescent↗
PubMed1987

Tissue distribution of rat S-100 alpha and beta subunit mRNAs.

Using Southern blot analysis it is demonstrated that S-100 alpha and beta genes were found as single copies in the rat genome. S-100 alpha mRNA was not found at all in rat brain during the developmental period, but it was slightly detectable in muscle and kidney. S-100 beta mRNA was detected in rat brain, and its mRNA level increased during the developmental period. The different localizations of the subunits may be due to the specific expression of each gene in various tissues.

Aging↗
PubMed1986

Molecular cloning of cDNA of S100 alpha subunit mRNA.

The primary structure of the bovine S-100 alpha mRNA on the basis of molecular cloning and sequence analysis of the cDNA are described. The sequence is composed of 532 bp which include the 282 bp of the complete coding region, 89 bp at the 5'-noncoding region, 161 bp at the 3'-noncoding region, polyadenylation signal, ATTAAA and poly(A) tail. Northern blot analysis shows that the size of S-100 alpha mRNA is about 700-800 bases long and a single mRNA occurs in bovine brain. Bovine brain contains both S100 alpha and beta subunits and their mRNAs. In contrast, the rat brain contains only S100 beta subunit and its mRNA.

Animals↗
PubMed1986

Sister-chromatid exchanges in the lymphocytes of people exposed to environmental cadmium.

Sister-chromatid exchanges (SCEs) were analyzed from peripheral lymphocyte cultures of 8 men and 16 women who had been exposed to environmental cadmium (Cd), and 6 controls. Average Cd concentrations in blood of the Cd-polluted group were 8.9 micrograms/l for men and 10.0 micrograms/l for women. These were no significant differences in SCE rates between the Cd-polluted and nonpolluted groups. There were no significant correlations between SCE rates and blood or urinary Cd concentrations. Cadmium alone may be an insignificant agent in producing chromosomal damage to peripheral blood lymphocytes.

Aged↗
PubMed1986

Hypokalemic myopathy associated with radiation enteropathy.

A case of a 68-year-old female patient with hypokalemic myopathy is presented. Her persistent diarrhea due to radiation enteropathy with a total dose of 8,400 rad for the treatment of cervical cancer caused potassium loss in the stool. It finally induced generalized muscle weakness with hypokalemia as low as 1.6 mEq/l with elevated CK 3,845 IU/l. The muscle biopsy of the left vastus lateralis demonstrated typical findings of hypokalemic myopathy. Radiation to the pelvic space can cause damage of the terminal ileum. Hypokalemic myopathy associated with radiation enteropathy is very rare in the literature.

Aged↗
PubMed1986

Diagnostic radioimmunoassay for familial amyloidotic polyneuropathy before clinical onset.

The purpose of this study is to develop an early diagnostic method for familial amyloidotic polyneuropathy (FAP) before clinical manifestations appear around the age of 30 yr. Amyloid fibrils isolated from type I FAP (FAP1) of Portuguese, Swedish, and Japanese origins consist of a variant transthyretin (TTR) that contains a methionine-for-valine substitution at position 30 or a mixture of normal TTR and this variant form. The variant TTR is present in the serum of FAP1 patients and can be measured by a radioimmunoassay (RIA) based on a nonapeptide (positions 22-30) derived from the variant TTR. Serum levels of the variant TTR in 45 Japanese FAP1 patients range from 4.71 to 17.61 mg/dl with a mean value of 9.18 mg/dl. The variant TTR is not present in the serum of 100 normal individuals, in four cases of primary and six cases of secondary amyloidosis, nor in 26 non-inheriting members of families with FAP1. The variant TTR level is measured in 24 children of 15 FAP1 patients as well. The variant TTR is already present in nine symptom-free children with the mean serum level of 11.90 mg/dl, but it is not present in 15 other children. FAP1 patients can be differentiated from non-FAP by this noninvasive diagnostic method even within families. The RIA can be applied worldwide to this intractable disorder for early diagnosis during childhood and for appropriate genetic counseling.

Adolescent↗