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Biomedical subjects

N Yasuda

Publications and source records attributed to N Yasuda.

At least 271 records · Page 15Linked to original sources
PubMed1985

Development of reflexes in neonatal mice prenatally exposed to methylmercury and selenite.

The development of reflexes in neonates exposed prenatally to methylmercury and selenite was investigated. Pregnant mice were assigned to one of 4 treatments; methylmercury (MeHg), selenite(Se), combination of 2 compounds (MeHg X Se) and saline control (NaCl). Mice were injected subcutaneously (s.c.) on day 9 of gestation. The dose of each compound was 30 mumol/kg. Mercury (Hg) concentrations in the neonatal brain and liver of the MeHg X Se group were slightly lower than in the MeHg group. The results of behavioral examination revealed that the MeHg X Se group showed significantly improved development compared with the MeHg group. These facts suggest the possibility that selenium compounds have protective effects against methylmercury neurotoxicity in fetuses and neonates.

Animals↗
PubMed1985

Nucleolus-associated localization of J chains in IgG 1(lambda)-producing myeloma cells.

By using both direct and indirect immunofluorescence technics and the PAP method, the authors observed an unusual immunocytochemical staining pattern in myeloma cells producing IgG 1(lambda). J chains were localized mainly as intranuclear spots, compared with gamma and lambda chains that are diffusely distributed in the cytoplasm with dense perinuclear accumulation. The present findings on the location, size, and number of the intranuclear spots suggest that J chains are nucleolus associated. The authors hypothesize that J chains are synthesized in the cytoplasm and transported into the nucleolus, where they associate with nucleolar proteins, or that they are synthesized within the nucleolus, which participates in biogenesis of ribosomes.

Bone Marrow↗
PubMed1985

Studies on the site of origin and molecular form of the extrahypothalamic corticotrophin-releasing factor (CRF) in rats.

A homologous radioimmunoassay was developed for rat CRF. CRF immunoreactivity was found widely in the extrahypothalamic areas in the rat central nervous system in concentrations 1-3% of that in the median eminence. Large hypothalamic lesions including the paraventricular nucleus and the median eminence did not cause a decrease in the extrahypothalamic CRF concentrations. CRF of the rat hypothalamus and cerebral cortex both consisted of high and low molecular weight forms. In contrast the posterior pituitary and the spinal cord contained only low molecular weight forms. Upon gel filtration the low molecular weight CRF of the hypothalamus co-eluted with synthetic rat CRF whereas that of the spinal cord was considerably more retarded. The low molecular weight CRF of the posterior pituitary and cerebral cortex was slightly more retarded compared to synthetic rat CRF. We conclude that CRF in many extrahypothalamic brain areas and the spinal cord does not originate from the hypothalamus and that there is some heterogeneity in the molecular form of the extrahypothalamic CRF.

Animals↗
PubMed1985

Studies on antiviral agents. II. Synthesis and in vitro antiviral activity on new kanamycin A derivatives having higher acyl group at N-1 position.

The synthesis and antiviral activity of 3''-N-trifluoroacetylkanamycin A derivatives (6) having higher acyl group at the N-1 position are described. On the basis of the structure-activity relationships between antiviral activity and alkyl chain length in an acyl group at the N-1 position, analogs (6f approximately I) having higher alkylcarbonyl group exhibited antiviral activity against not only HSV-I but also influenza virus. Analogs (6q approximately v) having higher alkyloxycarbonyl group showed antiviral activity against HSV-I. In addition, kanamycin A derivatives (6n, o, y, z) possessing higher alkylcarbonyl group with a functional group, higher alkylaminocarbonyl group, and higher alkylthiocarbonyl group had antiviral activity against HSV-I. The analog (6h) showed a broad antiviral spectrum against both DNA (HSV-I, HSV-II, VZV) and RNA (influenza) viruses.

Antiviral Agents↗
PubMed1985

Total synthesis of 3-O-demethylsporaricin A.

The novel, semisynthetic pseudodisaccharide antibiotic, 3-O-demethylsporaricin A, was synthesized via 3-O-demethylsporaricin B obtained by glycosidation of its aminocyclitol part. The aminocyclitol part was synthesized as D,L-form from D,L-(1,2,3/4,5,6)-1,4-bis(benzyloxy-carbonylamino)-5,6-O-isopropyl idene-2,3,5,6-cyclohexanetetraol via three key steps, namely, deoxygenation, inversion of a hydroxyl group, and N-methylation. The physical and biological properties of synthetic 3-O-demethylsporaricin A and an authentic sample derived from sporaricin B were identical.

Aminoglycosides↗
PubMed1985

Studies on antiviral agents. III. Synthesis and in vitro antiviral activity of 1-N-higher-acyl-3"-N-functionalized acylkanamycin A derivatives.

The synthesis and antiviral activity of 1-N-palmitoyl- or 1-N-(3-hydroxytetradecanoyl)-kanamycin A derivatives (7,8) having various type of acyl substituents at the N-3" position were investigated. The structure-activity relationships between the antiviral activity and the substituent at the N-3" position is described. In this series, 3"-N-acetyl-1-N-palmitoyl-kanamycin A (7c) showed the excellent antiviral activity against HSV-I and influenza virus. Further, we examined the synthesis and the antiviral activity of 3"-N-glycylkanamycin A derivatives (9) having a higher-acyl group at the N-1 position. The 3"-N-glycyl-1-N-pentadecanoylkanamycin A (9a) also exhibited excellent antiviral activity.

Amikacin↗
PubMed1985

Biological and immunological studies of bovine hypothalamic corticotropin-releasing factor.

Corticotropin-releasing factor B (CRF-B) is a peptide(s) isolated from bovine hypothalamic extracts by Sephadex G-100 chromatography on the basis of its ability to stimulate secretion of adrenocorticotropin (ACTH) in vitro and in vivo. It is similar in molecular size to the 41-residue ovine CRF (oCRF) or rat CRF (rCRF) recently elucidated and appears to be their bovine counterpart. Immunoreactivity of CRF-B was examined in homologous radioimmunoassays (RIAs) for oCRF or rCRF, using several anti-oCRF and anti-rCRF antibodies. CRF-B cross-reacted well with anti-oCRF antibodies but poorly with anti-rCRF antibodies. Purification of CRF-B with preparative isoelectric focusing yielded four CRF peaks, B-1 (pH 4.7), B-2 (pH 5.5), B-3 (pH 6.3), and B-4 (pH 7.0), which accounted for 16, 30, 46, and 8% of the total immunoreactivity, respectively. CRF B-2, B-3, and B-4 showed both immunological activity and biological activity in vitro (cell culture assay) and in vivo (Arimura assay), whereas CRF B-1 showed only immunoreactivity. Their relative bioactivity/immunoreactivity ratios were 0 (B-1), 1 (B-2), 1 (B-3), and 3 (B-4). All of these CRF-B subtypes exhibited RIA displacement curves parallel to that for the oCRF standard and coeluted with oCRF on Sephadex G-100 chromatography, which suggests that their molecular modifications are relatively minor.

Animals↗