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Biomedical subjects

H Kodama

Publications and source records attributed to H Kodama.

At least 505 records · Page 28Linked to original sources
PubMed1987

[4,4'-(Z)-dehydrophenylalanine]gramicidin S with stabilized bioactive conformation and strong antimicrobial activity.

Dehydrophenylalanine (delta Phe) was incorporated into an antibiotic peptide gramicidin S (GS) in place of D-Phe4,4' to prepare an unsaturated analog. Conformational analysis with 1H-NMR indicated that the unsaturated analog has much the same backbone conformation as that of natural gramicidin S as shown by NOE experiments. Studies on temperature dependences and on the chemical shift differences showed that the hydrogen bonds between Val-NH and Leu-CO in the unsaturated analog are strengthened by the incorporation of delta Phe4,4'. This resulted in the reinforcement of the beta-sheet structure which is the most important structural element for GS bioactivity. [delta Phe4,4']gramicidin S exhibited indeed very strong antimicrobial activities against Gram-positive bacteria as well as the natural peptide.

Circular Dichroism↗
PubMed1987

Suppression of NK activity of spleen cells by chicken fetal antigen present on Marek's disease lymphoblastoid cell line cells.

Chicken fetal antigen (CFA) expressed on the cell surface of Marek's disease (MD) lymphoblastoid cell line (MDCC-MSBI) cells was purified by affinity chromatography using a monoclonal antibody (2H3). A 4-hr 51Cr release assay was performed using spleen cells as effector cells to investigate the role of the CFA in the immune response of chickens, especially in relation to natural killer (NK) activity. Spleen cells of specific-pathogen-free (SPF) chickens showed reduced NK activity in the presence of CFA in vitro, as did those cells treated with MSBI soluble antigen. NK activity of spleen cells from chickens treated with CFA was also suppressed when compared to the cells from untreated or ovalbumin-treated chickens. In addition, MSBI clo. 18 transplantable tumors grew progressively in some of the 14-day-old chickens treated with CFA, whereas the tumors regressed in age-matched chickens with or without treatment by ovalbumin.

Animals↗
PubMed1987

Nucleotide sequences and unusual electrophoretic behavior of the W chromosome-specific repeating DNA units of the domestic fowl, Gallus gallus domesticus.

Nucleotide sequences of three independently cloned repeating units of the W chromosome-specific repetitive DNA sequences ("XhoI family") of the chicken were determined. All three units are 717 bp long with XhoI sites at both ends. There are only 21 sites out of 717 bases where a single base change occurs in one of the three clones. Each of these repeating units consists of 34 tandem repeats of about 21 bp. Sequences of some members of these internal repeats are not well conserved, but the majority of the repeats are characterized by the presence of (A)3-5 and (T)3-5 clusters separated by 6-7 relatively G + C-rich base pairs. One striking feature of the cloned 717 bp repeating units is that they migrate unusually slowly on electrophoresis in polyacrylamide gels. The same feature is also shown by a genomic population of the 0.7 kb repeating units recovered from XhoI digests of the genomic DNA of the female chicken. This anomalous behavior is attributed to the occurrence of DNA curvatures because of the above sequence characteristics and partial recovery of the electrophoretic mobility in the presence of distamycin A. Another feature of the 717 bp repeating unit is the presence of 438 and 159 nucleotide-long open reading frames (ORFs) at each end of the unit. A possible function of the XhoI family sequences in the heterochromatization of the W chromosome and the significance of the ORFs are discussed.

Animals↗
PubMed1987

Pathogenicity and immunogenicity in chickens of Newcastle disease viruses isolated from wild ducks. Brief report.

Three Newcastle disease viruses (NDV) isolated from wild ducks in Japan were evaluated for their biological activities, pathogenicity and immunogenicity against one-day-old chickens. One isolate was of the mesogenic type and the other two were of the lentogenic type for chicken. The lentogenic isolates could induce enough immunity in chickens to protect them from challenge with a virulent strain of NDV.

Animals↗
PubMed1987

Study on coacervation of the repeat pentapeptide model of tropoelastin: effect of cations.

The effects of various cations on coacervation of the polypentapeptide (Val-Pro-Gly-Val-Gly)n, a sequential model of tropoelastin, were studied by following the turbidity at 300 nm and the fluorescence intensity due to the interaction between the polypentapeptide and a hydrophobic probe (4-benzoylamido-4'-aminostilbene-2,2'-disulfonic acid). In the absence of cations, as the polypentapeptide concentration was increased, the turbidity curves shifted to lower temperatures and became much steeper, while the fluorescence intensity increased markedly. This suggests that a conformational change is induced by the association of the polypentapeptide molecules and indicates that coacervation occurs predominantly by intermolecular hydrophobic association. In the presence of Mg2+, the temperature profile of the coacervation curve of the polypentapeptide obtained by turbidity measurement moved to higher temperature and the fluorescence intensity decreased significantly. This suggests that Mg2+ inhibits the hydrophobic interaction of the polypentapeptide molecules on coacervation but does not induce conformational change on association of the molecules. In the presence of Ca2+, Na+, and K+, the temperature profile of the coacervation curve of the polypentapeptide was not affected appreciably, but the fluorescence intensity was decreased by these cations in the order of Na+, K+, and Ca2+. Circular dichroism spectra of the polypentapeptide in 80% trifluoroethanol in the presence of cations showed a less ordered state of the polypentapeptide. This less ordered state implies inhibition by the cations of the hydrophobic interaction between the molecules.

Cations↗
PubMed1987

Antigenic variation of Newcastle disease viruses isolated from wild ducks in Japan.

Nineteen strains of Newcastle disease virus (NDV) isolated from wild ducks in Japan were placed into 4 distinct antigenic groups on the basis of their reactivities to 8 monoclonal antibodies against the HN molecule of NDV in hemagglutination inhibition tests. The NDV strains of duck origin were antigenically distinct from NDV-B1 and NDV-Miyadera originated from chickens, and varied in their virulence to chicken embryos. No apparent correlation was found between the antigenicity of the HN molecule and virulence.

Animals↗
PubMed1987

Quantitative measurement of endotoxin in rainbow trout (Salmo gairdneri) serum by the chromogenic substrate method.

The amount of endotoxin in serum collected from normal rainbow trout (Salmo gairdneri) and trout inoculated with viable Vibrio anguillarum or lipopolysaccharide (LPS) extracted from bacteria was determined by the chromogenic substrate method. The mean values of endotoxin in four different groups of normal rainbow trout sera ranged from 31.9 to 65.3 pg/ml. When fish were inoculated with viable bacteria (1 x 10(8], they became septicaemic and a large amount of endotoxin ng/ml) was detected in the sera. In fish inoculated with a smaller number of bacteria the amount of endotoxin was several times higher than that of normal fish in spite of failure of bacterial isolation. Although the endotoxin level in serum increased rapidly (greater than 100 ng/ml) after intraperitoneal inoculation with purified V. anguillarum LPS (540 micrograms), no fish died during the experiment. The high level of endotoxin in normal rainbow trout and the resistance of trout to endotoxin are in striking contrast to those of mammalian and avian species.

Animals↗
PubMed1987

Effects of medroxyprogesterone acetate on sleep of healthy young male adults.

The effects of a single 100 mg dose of medroxyprogesterone acetate (MPA) on human sleep were investigated using healthy young male adults. After a baseline night recording, two consecutive MPA nights and the following two withdrawal nights were recorded. The total sleep time was reduced after the 2nd MPA night and the decrease was significant on the 1st withdrawal night. The time of intrasleep awakening increased after the 2nd MPA night. Stage 1 sleep increased significantly on the 2nd MPA and 1st withdrawal nights. Stage 4 sleep decreased and the sleep latency gradually increased after the MPA administration. REM sleep reduced slightly on the 1st withdrawal night. These results indicate that MPA has a mild arousal action on human sleep and that the action may be pronounced a few days after administration of MPA.

Adult↗