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Biomedical subjects

S Sasanuma

Publications and source records attributed to S Sasanuma.

At least 19 recordsLinked to original sources
PubMed2001

Disruption of Xpg increases spontaneous mutation frequency, particularly A:T to C:G transversion.

Cells isolated from Xpg (the mouse counterpart of XPG)-disrupted mice underwent premature senescence and showed early onset of immortalization, suggesting that Xpg might be involved in genetic stability. Recent studies showed that human XPG, in addition to its function in the nucleotide excision repair (NER), was involved in the repair of oxidative base damages such as thymine glycol (Tg) and 8-oxo-guanine (8-oxoG), and this may explain the genetic instability observed in Xpg-deficient cells. To clarify this point, we determined spontaneous mutation frequencies and the type of spontaneous base substitution mutations in cells obtained from normal and Xpg-deficient mice using the supF shuttle vector (pNY200) for mutation assay. The spontaneous mutation frequency of the supF gene in pNY200 propagated in the Xpg-deficient cells was about three times higher than that in normal cells, indicating the importance of Xpg in reducing the frequency of spontaneous mutations. The frequency of spontaneous base substitution mutations at A:T sites, particularly that of the A:T to C:G transversion, increased markedly in the Xpg-deficient cells.

Animals↗
PubMed2001

A mutation in the largest (catalytic) subunit of RNA polymerase II and its relation to the arrest of the cell cycle in G(1) phase.

Transcriptional activity of RNA polymerase II is modulated during the cell cycle. We previously identified a temperature-sensitive mutation in the largest (catalytic) subunit of RNA polymerase II (RPB1) that causes cell cycle arrest and genome instability. We now characterize a different cell line that has a temperature-sensitive defect in cell cycle progression, and find that it also has a mutation in RPB1. The temperature-sensitive mutant, tsAF8, of the Syrian hamster cell line, BHK21, arrests at the non-permissive temperature in the mid-G(1) phase. We show that RPB1 in tsAF8--which is found exclusively in the nucleus at the permissive temperature--is also found in the cytoplasm at the non-permissive temperature. Comparison of the DNA sequences of the RPB1 gene in the wild-type and mutant shows the mutant phenotype results from a (hemizygous) C-to-A variation at nucleotide 944 in one RPB1 allele; this gives rise to an ala-to-asp substitution at residue 315 in the protein. Aligning the amino acid sequences from various species reveals that ala(315) is highly conserved in eukaryotes.

Amino Acid Sequence↗
PubMed2001

Characteristic association between K-ras gene mutation with loss of heterozygosity in X-ray-induced thymic lymphomas of the B6C3F1 mouse.

PURPOSE: To elucidate the characteristics of radiation carcinogenesis, the spectra of K- and N-ras oncogene mutations, loss of heterozygosity (LOH) and their association in X-ray-induced thymic lymphomas (TL) were determined by comparing with those of N-ethyl-N-nitrosourea (ENU)-induced and spontaneously occurring TL. MATERIALS AND METHODS: TL that arose in untreated, X-ray-irradiated and ENU-treated B6C3F1 mice were examined both for K- and N-ras mutations by PCR-SSCP and DNA sequencing and for LOH by PCR with polymorphic microsatellite markers. RESULTS: (1) ras gene mutations were found in a proportion of TL from X-ray-exposed (approximately 20%) and ENU-treated (30-40%) mice while no ras gene mutations were found in spontaneous TL. N-ras mutations were rare. (2) The spectrum of ras gene mutations was diverse and seemed to differ little between X-ray-induced and ENU-induced TL, even though there was a higher frequency of ras mutations in ENU-induced TL that clustered to K-ras codon 12. (3) The X-ray-induced TL showing K-ras mutation were associated with LOH on chromosome 6, while those showing no K-ras mutation were associated with high frequency of LOH on chromosomes 4, 11 and 12. CONCLUSION: These results demonstrate that, in the B6C3F1 mouse TL, X-ray-induced lymphomagenesis showed both the co-expression, yet low occurrence of allelic imbalance on chromosome 6 and K-ras mutation, and exclusive expression of frequent allelic imbalance on chromosomes 4, 11 and 12 and K-ras mutation.

Animals↗
PubMed1998

The interaction of preserved pragmatics and impaired syntax in Japanese and English aphasic speech.

Elicited narrative studies have shown that the underlying pragmatic factor of empathy is relatively preserved in aphasic speakers of Japanese and English (7 Japanese and 14 English-speaking aphasics of varied diagnostic types). Occasional "reversal errors" can be explained in terms of a conflict between the normal encoding of the empathic characteristics of an event and the syntactic limitations imposed by impaired production processes. To account for these findings, we propose a production model following Levelt (1989) for making pragmatic choices among syntactic forms. We also suggest that preferential access to "canonical form" might be a matter of surface morphosyntax, rather than involving semantics or more abstracts levels of syntax.

Adolescent↗
PubMed1998

Orthography and phonology in reading Japanese kanji words: evidence from the semantic decision task with homophones.

Correspondences between spelling and sound for Japanese kanji are complex and deep. The meaning of kanji words has generally been assumed to be accessed directly from orthography without phonological mediation. Experiment 1, however, replicated the findings of Van Orden (1987) that subjects made more false-positive errors on homophone foils than they did on nonhomophone controls in a semantic decision task, although they did so only when the foils were orthographically similar to the correct exemplars, which indicates both orthographic and phonological activations of meaning. Experiment 2 showed the same results when subjects were not required to pronounce the target words after semantic decisions, which indicates automatic phonological activation of kanji words. In Experiment 3, under pattern-masking conditions, this homophony effect was reduced but remained on errors, and the orthographic-similarity effect remained strong on both homophone and nonhomophone foils. These results suggest that both orthography and phonology play an important role in the comprehension of kanji words.

Adult↗
PubMed1997

Cloning and sequencing for the largest subunit of Chinese hamster RNA polymerase II gene: identification of a mutation related to abnormal induction of sister chromatid exchanges.

In order to analyze the mutation sites related to abnormal induction of sister chromatid exchanges (SCEs) in the RNA polymerase II largest subunit (RpII LS) gene of the Chinese hamster CHO-KI cell mutant, we have completely sequenced the whole region of the RpII LS cDNAs obtained from normal and mutant cells. By comparing both sequences, a mutation that results in an amino acid (aa) change in the RpII LS gene was found. This aa change was Pro (CCC) to Ser (TCC) at position 1006. Multiple alignment for aa sequences of RpII LS from various species revealed that this Pro residue was highly conserved throughout the eukaryotes. Considering the differences in physico-chemical properties between Pro and Ser residues, the Pro-->Ser substitution may alter the RpII LS structure.

Amino Acid Sequence↗
PubMed1997

Gene organization of human NOTCH4 and (CTG)n polymorphism in this human counterpart gene of mouse proto-oncogene Int3.

The cDNA and genomic clones for the human counterpart of the mouse mammary tumor gene Int3 were isolated and sequenced. We designated this human major histocompatibility complex (MHC) class III gene as NOTCH4, since very recently, by sequencing cDNA clones, the complete form of the mouse proto-oncogene Int3 has been clarified and named Notch4. The present human NOTCH4 sequence is the first example of the genomic sequence for the extracellular portion of the mammalian Notch4, and by comparing it with the mouse Notch4 cDNA sequence, the exon/intron organization was clarified. The comparison of the predicted amino acid sequence of human NOTCH4 with those of other Notch homologues of a wide range of species revealed four subfamilies for mammalian Notch. In the protein coding region of human NOTCH4, we found (CTG)n repeats showing a variable number tandem repeat (VNTR) polymorphism for different human leukocyte antigen (HLA) haplotypes. Ten genes mapped on 6p21.3, including NOTCH4, were found to have counterparts structurally and functionally similar to those mostly mapped on 9q33-q34, indicating segmental chromosome duplication during the course of evolution. Similarity of genes on chromosomes 1, 6, 9 and 19 was also discussed.

Amino Acid Sequence↗
PubMed1996

Fifteen open reading frames in a 30.8 kb region of the right arm of chromosome VI from Saccharomyces cerevisiae.

The nucleotide sequence of cosmid clone 9765, which contains 30.8 kb of the right arm of chromosome VI, was determined. Both strands were sequenced, with an average redundancy of 8.17 per base pair by both dye primer and dye terminator cycle sequencing methods. The G+C content of the sequence was found to be 40.3%. Fifteen open reading frames (ORFs) greater than 100 amino acids and one tRNA-Tyr gene (SUP6) were detected. Seven of the ORFs were found to encode previously identified genes (HIS2, CDC14, MET10, SMC2, QCR6, PH04 and CDC26). One ORF, 9765orfF010, was found to encode a new member of the Snf2/Rad54 helicase family. Three ORFs (9765orfR002, 9765orfR011 and 9765orfR013) were found to be homologous with Schizosaccharomyces pombe polyadenylate binding protein, Escherichia coli hypothetical 38.1-kDa protein in the BCR 5' region, and transcription regulatory protein Swi3, respectively.

Adenosine Triphosphatases↗
PubMed1995

Sequencing of an 18.8 kb fragment from Saccharomyces cerevisiae chromosome VI.

The nucleotide sequence of lambda phage clone 4121, which contains the 18.8 kb fragment of Saccharomyces cerevisiae chromosome VI left arm, was determined. This sequence had seven open reading frames (ORFs), four of which were identical to known genes (ACT1, YPT1, TUB2 and RPO41). Another three ORFs (4121orfR003, 4121orfR004 and 4121orfRN001) were highly homologous to FET3 multi-copper oxidase, glucose transport protein, and hypothetical protein of YIL106w on chromosome IX, respectively. 4121orfRN01 is suggested to contain an intron.

Amino Acid Sequence↗
PubMed1995

Analysis of the nucleotide sequence of chromosome VI from Saccharomyces cerevisiae.

The complete nucleotide sequence of Saccharomyces cerevisiae chromosome VI (270 kb) has revealed that it contains 129 predicted or known genes (300 bp or longer). Thirty-seven (28%) of which have been identified previously. Among the 92 novel genes, 39 are highly homologous to previously identified genes. Local sequence motifs were compared to active ARS regions and inactive loci with perfect ARS core sequences to examine the relationship between these motifs and ARS activity. Additional ARS sequences were predominantly observed in 3' flanking sequences of active ARS loci.

Base Composition↗
PubMed1991

Constructional praxis performance of Japanese and American, normal and brain-damaged patients.

Numerous studies have suggested population differences between Japanese and Americans concerning various cognitive functions. Transcultural differences in spatial reasoning, language, and dominance for emotional expression raise important questions concerning current conceptions of hemispheric cerebral dominance for cognitive functioning. If cultural differences in cognition exist, learning may play a greater role in determining laleralizalion of cognitive functions than is presently accepted. To investigate these issues, we initiated two collaborative studies comparing Japanese with American normals and brain-damaged patients on the Three-Dimensional Constructional Praxis Test. In normal subjects, there were no significant differences between the two cultures in the distribution of visuoconstructive ability. In patients with brain damage, the effects of unilateral brain lesions and their neuropsychological consequences on visuoconstructive ability were similar in both cultures. Thus, there are no apparent differences between the Japanese and American peoples in visuoconstructive abilities, or in the underlying cerebral organization of skills required to execute these functions.

Journal Article↗
PubMed1990

Sex differences in cognitive abilities: a cross-cultural perspective.

Studies in Western cultures have indicated significant sex differences in certain cognitive abilities. To determine whether similar differences occur in a non-Western culture, this study administered a cross-linguistic battery of tests to high school students in Japan and America. In both cultures, girls averaged significantly higher scores on a Story Recall test, the Digit-Symbol test and a Word Fluency test whereas boys achieved significantly higher scores on a Mental Rotation test. The analysis of standardized test scores further indicated that the size of the sex difference was culture-independent in three out of these four cases. These results are discussed in the context of the GESCHWIND and GALABURDA [Cerebral Lateralization, Biological Mechanisms, Associations and Pathology, Bradford Books, Cambridge, Massachusetts] account of the contribution of testosterone to left-right asymmetries in early cerebral development.

Adolescent↗
PubMed1989

[Recognition units of kanji words: priming effects on kanji recognition].

We investigated the recognition units of single-kanji and two-kanji-compound words in lexical access. In Experiment 1, we examined if the word recognition is facilitated in two conditions: (1) when the prime and the target words are identical and (2) when the prime and the target words contain an identical kanji. The priming effect was found only when the compound targets were identical to the prime. In Re-experiment 1, facilitation among kanji word was re-examined. The priming effect was obtained in the identical targets in both single and compound words. In Experiment 2, facilitation of word recognition among single kanji words was investigated. The results showed that facilitation was observed when the target was identical to the prime. Taken together, these results indicated that the kanji word recognition in lexical access is accomplished by word-sized units rather than by character-sized units. The findings were discussed with reference to the logogen model (Morton, 1977).

Adult↗
PubMed1988

Internal representations and the conceptual operation of color in pure alexia with color naming defects.

This research examined the structure of internal representation and the conceptual operation of color in two pure alexic cases (Case I and Case II) with color naming defects. Experiment I investigated the structure of the internal representation of different kinds of colors using a similarity judgment task. Experiment II examined categorical judgments of perceived colors using a two-alternative-forced choice task. Experiment III tested the classification of perceived colors using a color sorting task. The performance of Case I essentially fell within the normal range while the results of Case II showed some impairment in the conceptual operation of color. Analysis of the responses obtained from these experiments indicated that the color naming defects in Case I can be explained in terms of visual-verbal disconnection. However, the naming defects in Case II reflect disfunction in some other higher cortical processes coupled with visual-verbal disconnection.

Color Perception↗
PubMed1986

Voice onset time perception in Japanese aphasic patients.

This study examines identification of the synthetic speech stimuli [ga] and [ka] of varying voice onset times (VOTs) in 17 Japanese aphasic subjects. Approximately two-thirds of the aphasic subjects showed deterioration in performance of VOT identification of the stimuli. A quantitative analysis of the results indicates that the problems of the majority of these subjects may be attributable not only to difficulty in labeling the stimuli but also to difficulty in processing the acoustic and/or phonetic information of the stimuli.

Adult↗
PubMed1985

Subcortical aphasia with deep dyslexia: a case study of a Japanese patient.

The reading performance of a Japanese Broca-type aphasic patient on a single-word reading test was investigated. The result indicated that the subject fits the symptom complex of deep dyslexia in more than one aspect. Unique characteristics of this subject included (1) the isolated subcortical site of the lesion, which apparently produced deep dyslexia, and (2) double dissociations between kanji and kana processing and between oral reading and reading comprehension. The performance of this subject was compared with that of another Japanese deep dyslexic subject in S. Sasanuma (1980, In M. Coltheart, K. Patterson, & J. C. Marshall (Eds.), Deep dyslexia, London: Routledge & Kegan Paul). A theoretical implication was attempted based on a dual coding process scheme by S. Sasanuma and O. Fujimura (1978, Cortex, 7, 1-18).

Aphasia↗