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Biomedical subjects

K Hamada

Publications and source records attributed to K Hamada.

At least 505 records · Page 28Linked to original sources
PubMed1980

Dinucleoside monophosphate having a high anti conformation. II. The crystal structure of 8,2'-S-cycloinosinyl-(3',5')-8,2'-S-cycloadenosine hexahydrate.

The crystal and molecular structure of 8,2'-S-cycloinosinyl-(3',5')-8,2'-S-cycloadenosine (IspAs) hexahydrate has been determined by X-ray diffraction method. The torsion angles around the sugar-phosphate backbone are unique and different from those found in the crystalline dinucleoside monophosphates so far determined. The rotation around the P-O bond, (omega',omega), is (g+,t). An IspAs molecule is in a folded form. There is no intramolecular base stacking or base-pairing but the intermolecular base stacking is dominant.

Base Composition↗
PubMed1979

Incontinentia pigmenti achromians as part of a neurocutaneous syndrome: a case report.

A case of incontinentia pigmenti achromians associated with mental retardation, epilepsy, short stature and ocular anomalies was reported. A study of this case together with a review of the 38 cases in the literature revealed that this entity has been associated with central nervous system involvements at a high frequency. It is necessary, therefore, to consider incontinentia pigmenti achromians as a neurocutaneous syndrome from the viewpoint of pediatric neurology.

Child↗
PubMed1978

Mutagenicity in Salmonella typhimurium mutants of the benzene-soluble organic matter derived from air-borne particulate matter and its five fractions.

Air-borne particulate matter was collected on a filter, then extracted with benzene. The benzene-soluble material was separated into 5 fractions, namely acidic, basic, alipathic, polyaromatic and oxygenated fractions. The mutagenic activities of these fractions were examined with a set of Salmonella typhimurium mutants. The 6 mutants were from the TA1535 series, deep rough strains without excision repair, namely TA100 and TA98 (having a resistance-transfer factor) and the standard strain TA1535, TA1536, TA1537 and TA1538. Linear dose-response curves were obtained for the benzene-soluble organic matter, and its acidic, polyaromatic and oxygenated fractions with strain TA98 and a 9000 X g liver supernatant from both phenobarbital(PB)- and dibenz(a,h)anthracene(DBA)-treated rats. Among the 5 fractions tested, 3 fractions, namely the acidic, polyaromatic and oxygenated, played an important role in the mutagenicity of the benzene-soluble organic matter derived from air-borne particulate matter. The 9000 X g rat-liver supernatant was not required to make the acidic fraction mutagenic.

Air Pollutants↗
PubMed1978

Induction and isolation of frameshift mutants in cultured Chinese hamster DON cells.

Induction, isolation and characterization of frameshift mutants were studied by using a Chinese hamster Don (CHD) cell line. ICR-191, known to be a potent frameshift mutagen, was used for the induction of frameshift mutations. The drug (10(-5) M), as well as N-methyl-N'-nitro-N-nitrosoguanidine (MNNG) and ethyl methanesulfonate (EMS), increased significantly the frequency of forward mutations from 8-azaguanine (8-AG) sensitivity (8-AGs) to resistance (8-AGr) over the untreated control to an extent of about 100-fold. 21 8-AGr mutants were isolated from the AP-01 (a sub-line of CHD) cells after treatment with appropriate concentrations of ICR-191 (10(-5) and 1.36 X 10(-5) M), and subsequently several reclonal mutants were tested for their ability to revert to 8-AG susceptibility after treatment with the three mutagens and a carcinogen, 2-nitrofluorene (2-NF), known to be a frameshift mutagen. Among the 8-AGr mutants tested, clone ICR-014 or ICR-172 showed a significant increase in reversion frequency over the control level only after treatment with ICR-191 or 2-NF, respectively; but not with the other two mutagens. These results suggest that each of these two kinds of mutant has a different frameshift mutation in one of the loci controlling 8-AG resistibility. It was also found that the hypoxanthine--guanine phosphoribosyl transferase (HGPRT) activities in clones ICR-014 and ICR-172 were 1.9 and 34% of that of the original AP-01 cells, respectively.

Acridines↗
PubMed1978

Simultaneous competitive enzyme immunoassay for human chorionic gonadotropin.

A simultaneous competitive enzyme immunoassay (SICEIA) for hCG was developed using beta-D-galactosidase (beta-Gal) as a labelled enzyme and anti-hCG antibody coated sheep red blood cells (SRBC) as a solid phase. In this report, a new coupling agent, MCAE, was used to couple beta-Gal with hCG. The sensitivity was improved to the degree of 2.5 mIU/ml, equal to that of RIA. The present procedure was safer and rapider than RIA. The value of hCG in urine by our procedure had good correlation with that by RIA.

Binding, Competitive↗
PubMed1977

A female case of Kallmann's syndrome.

A case of 20-year-old woman with hypogonadotropic hypogonadism and anosmia is reported, since very few female cases of Kallmann's syndrome have been reported so far in Japan. Three uncles on the father's side had no children. Height was 168 cm, and arm span 165 cm. The olfactory test revealed complete anosmia. Bone age was 13 year. Chromosome was 46 XX and normal karyotype. Basal levels of serum FSH, LH and estrogens (E1, E2 and E3) were low. Serum FSH and LH levels rose slightly only after LH-RH administration, and did not increase in clomiphene test. Plasma estrogens did not increase after daily injection of 150 IU of HMG for 3 successive days. The response of serum GH to arginine infusion was normal, while that to insulin-induced hypoglycemia was poor.

Adult↗
PubMed1977

Chronic toxicity of 2-(2-furyl)-3-(5-nitro-2-furyl) acrylamide (AF-2) in mice, with special reference to carcinogenicity in the forestomach.

Chronic toxicity of 2-(2-furyl)-3-(5-nitro-2-furyl)acrylamide (AF-2), which had been widely used in Japan as a food additive, was studied in both sexes of ICR/JCL mice by feeding a diet containing AF-2 in a concentration of 0.4% or 0.08%. The experiments confirmed its definite carcinogenicity in the forestomach, with dose dependency; more than 70% of mice fed the higher dose developed tumors, the majority of which were squamous cell carcinomas with metastatic growths, whereas, with a lower dose, fewer tumors occurred, following a longer latent period. In addition, possible leukemogenicity was suggested by a higher incidence in AF-2-fed females (10.8%) over that in control females (3.2%). The development of non-neoplastic lesions in the liver and kidneys, and of amyloidosis in various organs was also observed in some of AF-2-fed mice.

Animals↗
PubMed1975

Quantitative relationship between carcinogenicity and mutagenicity of polyaromatic hydrocarbons in Salmonella typhimurium mutants.

Mutagenic activities of various polyaromatic hydrocarbons (PAHs) in air pollutants, which are different in carcinogenic activities from each other, were examined with a set of four strains of Salmonella typhimurium (TAI535 series; deep rough strains without excision repair). All the compounds tested were converted to frameshift mutagens when they were metabolized by rat liver homogenate. There was a clear quantitative correlation between carcinogenicity and mutagenicity of PAHs tested in strain TAI538 using the rat liver enzyme induced with both dibenz(a,h)-anthracene and phenobarbital. On the other hand, such a correlation was not obvious in strain TAI537.

Air Pollutants↗