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Biomedical subjects

S Tsuji

Publications and source records attributed to S Tsuji.

At least 883 records · Page 49Linked to original sources
PubMed1986

Preclinical increase in activity of muscle microsomal trypsin-like protease in murine muscular dystrophy, C57BL/10-mdx.

Preclinical alterations of protease activities in skeletal muscles from 10-day-old dystrophic mouse, C57BL/10-mdx, were examined by using 10 fluorogenic peptide substrates. Among the activities tested, only Boc-Val-Pro-Arg-MCA-hydrolyzing enzyme of the muscle microsomes showed an about 6-fold higher level of activity in mdx mouse. The increase in activity was not observed in tissues other than skeletal muscle. The enzyme had a pH optimum between 8.5 and 11.0, and was inhibited with DFP and variety of trypsin inhibitors. The enzymatic activity transiently increased at 1-2 weeks of age, the preclinical or very early stage of the disease. These results imply that the increased level of a trypsin-like protease possibly present in muscle microsomes may be closely related to the manifestation of muscular dystrophy.

Aging↗
PubMed1986

Bioactive gangliosides: analysis of functional structures of the tetrasialoganglioside GQ1b which promotes neurite outgrowth.

Previous reports from our laboratory showed that tetrasialoganglioside GQ1b, when exogenously added, can promote cell proliferation and neurite outgrowth in two human neuroblastoma cell lines, GOTO and NB-1 (Tsuji, S., Arita, M. and Nagai, Y. (1983) J. Biochem. 94, 303-306). To clarify the activity-associated structure of GQ1b, we analyzed the structure-activity relationships using the GQ1b molecule, derivatives of it, and related gangliosides. When the GQ1b molecule was divided into two parts, the ceramide and oligosaccharide moieties, no activity was found with the former, while with the latter the activity could be seen, although the level of activity obtained never exceeded half that of GQ1b itself and an optimal concentration of 100-200 ng/ml of 20-40-times that of native GQ1b (5 ng/ml) was required. Furthermore, the activity of GQ1b was completely abolished by neuraminidase treatment, which converted GQ1b to GM1, so we examined other molecular species of gangliosides having a common gangliotetraose backbone but linked differently with two to four sialic acids (i.e., GD1a, GD1b, GT1a, GT1b, GQ1b and GQ1c). Among them, only GQ1b was found to be active. The results disclosed the interesting fact that deletion of any sialic acid residue from either of the two disialosyl residues of GQ1b results in a complete loss of activity and that the mere existence of the tetrasialosyl structure does not lead to activity; this indicates the absolute necessity of the GQ1b oligosaccharide structure for the expression of activity. For full expression of the activity, both the ceramide and oligosaccharide moieties were necessary. It was also found that the GQ1b oligosaccharide inhibited the activity of GQ1b at a concentration a few times greater than that of GQ1b, suggesting the involvement of a receptor-like mechanism in the action of GQ1b at the cell membrane.

Carbohydrate Conformation↗
PubMed1986

Nucleotide sequence of cDNA containing the complete coding sequence for human lysosomal glucocerebrosidase.

Complementary DNA clones for human glucocerebrosidase were isolated from a human hepatoma library in lambda gt11. The complete nucleotide sequence of the 1805-base pair cDNA insert has been determined. In addition to 5' and 3' untranslated regions (51 and 206 base pairs, respectively), the cDNA insert contains 1548 base pairs that completely encode human glucocerebrosidase. All possible N-linked glycosylation sites are identified. Examination of the 19 amino acids of the leader polypeptide beginning with the ATG at position 52 revealed a hydrophobic core and a carboxyl-terminal glycine at the peptidase cleavage site, features consistent with the leader sequences described for other human translocated proteins. The Mr of 57,000 calculated from the 516 amino acids deduced from cDNA sequence is in good agreement with that identified by immunoprecipitation following in vitro translation of human placental mRNA.

Amino Acid Sequence↗
PubMed1986

Isolation of temperature-sensitive mouse FM3A cell mutants exhibiting conditional chromosomal instability.

Fourteen mutants exhibiting conditional induction of sister chromatid exchanges (SCEs) and/or chromosomal aberrations (CAs) were selected out of 65 temperature-sensitive (for growth) mutants from mouse FM3A cells treated with N-methyl-N'-nitro-N-nitrosoguanidine. The mutants with chromosomal abnormality at the nonpermissive temperature were classified into three groups. The group 1 mutant manifested mainly SCEs at the nonpermissive temperature. The group 2 mutants manifested both SCEs and CAs. The group 3 mutants, including ts-131b, a mutant defective in DNA replication and previously described, manifested only CAs. A substantial number of SCEs accompanied by CAs at the site of SCEs were observed in some of the group 2 mutants at the nonpermissive temperature. The results suggest that there are at least three processes involved in the formation of SCEs and CAs, one is common to both phenomena while the others are independent. Some other mutants belonging to the groups 1 and 2 displayed a high incidence of interchromosomal chromatid exchanges at the nonpermissive temperature, suggesting that the same genetic defects leading to high induction of SCEs correlate with induction of chromosomal rearrangements. From these results, the group 2 mutants were subdivided further into five classes, and the mutants in each class had different cytogenetic properties from one another. This indicates defects in at least several genes that participate in the production of SCEs or CAs. The mutants described should be useful for analyzing the mechanisms of SCE or CA formation, and also the mechanism of chromosomal rearrangements.

Animals↗
PubMed1986

Successful treatment of murine muscular dystrophy with the protease inhibitor bestatin.

Continued administration of the dipeptide protease inhibitor Bestatin to 34 mice with genetic muscular dystrophy from the onset of clinical deficit, cured about half of the animals within 3 months. Cessation of treatment in the recovered mice at age 4 months was not followed by relapse. Examinations of these mice revealed recovery of (1) weight gain and life span, (2) muscle strength, and (3) marker enzyme activities in skeletal muscle and serum, as well as (4) disappearance of myopathological features characteristic of the disease such as necrosis of muscle fibers, centralization or a chain like arrangement of nuclei, or a marked infiltration of collagenous fibers. Finally, (5) the genetic confirmation of the animals which attained remission was confirmed to be dy/dy.

Animals↗
PubMed1986

Scalp topography and distribution of cortical somatosensory evoked potentials to median nerve stimulation.

Topographies and distributions of cortical SEPs to median nerve stimulation were studied in 8 normal adults and 5 neurological patients. SEPs recorded from C4, P4, Pz, T6-A1A2 derivations to left median nerve stimulation were composed of 2 early negative (N16, N20) and 2 positive components (P12, P23), whereas those recorded from frontal electrodes (Fz, Fp1, Fp2) disclosed 2 early negativities (N16, N24) and 2 early positivities (P12, P20). N20 and P20, and P23 and N24, reversed across the rolandic fissure with no significant difference in their peak latencies. P23 was of slightly shorter latency at C4 than at more posterior electrodes (P4, T6, Pz). In 3 patients with complete hemiplegia but normal sensation, all the early SEP components were normal in scalp distribution and peak latencies except for a decrease of N24 amplitude. In 2 patients with complete hemiplegia and sensory loss no early cortical SEPs were seen. These findings suggest that N20 and P20 are generated as a single horizontal dipole in the central fissure, whereas P23 and N24 are a reflection of multiple generators in pre- and postrolandic regions.

Adult↗
PubMed1986

Aphidicolin-resistant mutants of mouse lymphoma L5178Y cells with a high incidence of spontaneous sister chromatid exchanges.

Two aphidicolin-resistant cell mutants (AC 12 and AC 41) with a fourfold increase in spontaneous frequency of sister chromatid exchanges (SCEs) were obtained out of over 400 aphidicolin-resistant mutants isolated from mouse lymphoma L5178Y cells. They also exhibited three- to fourfold increases in spontaneous frequency of chromosome aberrations (CAs). To determine whether the high level of SCE frequency in AC 12 is caused by 5-bromodeoxyuridine (BrdUrd) used for visualizing SCEs, the effect of BrdUrd incorporated into DNA on SCE induction was analyzed. The SCE frequencies in AC 12 remained constant at BrdUrd incorporation levels corresponding to 2-90% substitution for thymidine in DNA. In addition, the small amount of BrdUrd incorporated into both daughter and parenteral DNA strands in AC 12 had minimal effect on SCE induction. Furthermore, AC 12 and AC 41 were slightly resistant to BrdUrd with respect to the induction of CAs, the inhibition of cell-cycle progression and the decrease in mitotic activity. These findings suggest that the high incidence of SCEs in AC 12 and AC 41 is formed by their intrinsic defects, not by the effects of BrdUrd used. The analysis of SCE frequencies in hybrid cells between these mutants and the parental L5178Y revealed that the genetic defects in AC 12 and AC 41 appear to be recessive, and that these two mutants belong to the same complementation group. Furthermore, AC 12 belonged to a different complementation group from ES 4, which was isolated previously from L5178Y as an SCE mutant with a twofold higher frequency of spontaneous SCEs. This finding indicates that at least two different genetic defects participate in the formation of the high incidence of spontaneous SCEs in mouse cells. These SCE mutants would provide valuable cell materials for studying the molecular mechanism of SCE formation.

Animals↗