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Biomedical subjects

A Asano

Publications and source records attributed to A Asano.

At least 73 records · Page 4Linked to original sources
PubMed1992

Quantitation of changes in mitochondrial DNA during aging and regeneration of rat liver using non-radioactive DNA probes.

By using DNA probes prepared from cloned cells which contain mitochondrial DNA (mtDNA) sequences in plasmids, the specific detection of mtDNA became possible in the presence of large excess of nuclear DNA by DNA-DNA hybridization. For this purpose, we prepared mtDNA probes labeled with non-radioactive substrate, which allowed a wider possibility of application. This method revealed that the contents of mtDNA in rat liver are strikingly decreased during aging. Furthermore, it was observed that although mtDNA content increased upon partial hepatectomy even in old rats, it decreased to the pre-operation level rather rapidly within 1 week after reaching peak in regenerated liver.

Aging↗
PubMed1991

The characteristic CD spectra of DNA from young rat liver.

The circular dichroism spectroscopy was used to study conformational changes of DNA upon aging. DNA from 8 weeks old rat liver showed A-form unexpectedly in physiological saline. The characteristic spectrum gradually changed upon aging and that of 30 months old rat liver DNA showed normal B-form.

Aging↗
PubMed1990

Direct evidence for the presence of methylmercury bound in the thyroid and other organs obtained from mice given methylmercury; differentiation of free and bound methylmercuries in biological materials determined by volatility of methylmercury.

Peroxidase in mouse thyroid was inhibited by mercuric chloride but not by methylmercury in in vivo and in vitro systems (Nishida, et al., J. Histochem. Cytochem., 37, 723 (1989)). To identify the reason for the difference, the present study was conducted to examine whether methylmercury is indeed bound within cells or tissues. Mice were given radioactive methylmercury by intubation for 18 d and the tissues were dissected out and vacuum-dried. With this procedure, free methylmercury was evaporated off and the bound mercury remained. The thyroid, liver, kidney and fats examined showed no loss of radioactivity under the vacuum, indicating that the mercury was bound to the thyroid, as well as the other tissues. Radioactive mercuric chloride was nonvolatile regardless of the presence or absence of the tissues. The preferential affinity of methylmercury for SH-containing materials was re-confirmed by this method.

Animals↗
PubMed1990

Family history of cancer and mortality among patients gastrectomized because of benign gastric diseases.

A preliminary result from a cohort study on the association of a family history of cancer with mortality is discussed in this paper. Among 2200 patients (1912 males and 288 females) gastrectomized because of benign gastric diseases, 274 male patients, and 40 female patients had a family history of cancer. During 2750 person-years of observation, 22 patients with the family history of cancer were found to be dead and 111 patients without the family history died during 17,527 person-years, giving a relative risk of 1.26 (not significant). We focused on the male subjects that were followed up for more than 10 years; however, the observed/expected ratio of cancer deaths for subjects with a family history of cancer was about four times higher than that for those without family history. Since case-control studies on family history are vulnerable to biased recall and interchangeability of cases, more cohort studies like the present study should be conducted to assess the association of the family history of cancer.

Case-Control Studies↗
PubMed1988

Binding of cholesterol and inhibitory peptide derivatives with the fusogenic hydrophobic sequence of F-glycoprotein of HVJ (Sendai virus): possible implication in the fusion reaction.

Specificity of the binding of sterols and related compounds with purified F-protein (fusion protein) of the HVJ (Sendai virus) was studied by binding competition with [3H]cholesterol. Requirement for cholesterol or the A/B ring trans structure and nonrequirement for the 3-hydroxyl group were found in this binding. Binding of 125I-labeled Z-Phe-Tyr, an inhibitory peptide of viral membrane-cell membrane fusion, was studied by using purified proteins and virions. F-Protein and virions showed a specific binding with the peptide, whereas the result was negative with hemagglutinin and neuraminidase protein. Thermolysin-truncated F-protein (an F-protein derivative deprived of a 2.5-kDa fragment from the N-terminal of the F1 subunit and without fusogenic activity) exhibited a considerably diminished binding ability both to cholesterol and to inhibitory peptides. Therefore, the N-terminal hydrophobic sequence that was previously assigned as fusogenic seems to be the binding site of these molecules. In support of this, the binding of cholesterol with F-protein was inhibited by Z-Phe-Tyr and other fusion inhibitory peptides, whereas it was not affected with non-fusion-inhibitory Z-Gly-Phe. These results are discussed in relation to the notion that the binding of the N-terminal portion of the F1 subunit of F-protein with cholesterol in the target cell membranes facilitates the fusion reaction.

Animals↗
PubMed1988

Characteristic structures of actin gels induced with hepatic actinogelin or with chicken gizzard alpha-actinin: implication for their function.

We studied the properties of actinogelin, a Ca2+-regulated actin cross-linking protein isolated from Ehrlich tumor cells or rat liver. Chicken gizzard alpha-actinin was used as a Ca2+-insensitive control. Actinogelin, which has very high gelation activity under low Ca2+ conditions, was found using electron microscopic or fluorescence studies to induce formation of a characteristic structure in which actin filaments and bundles radiate to (or converge from) all directions from spot-like core structures. A similar structure was induced with actinogelin, even in the presence of 0.7 saturation of tropomyosin. No such structure was detected with actinogelin under high Ca2+ conditions, and only a few were found with gizzard alpha-actinin. Because reconstituted structures are similar to those observed intracellularly, actinogelin may be important in the formation of similar microfilament organization in the cells. It seems also important that these structures are reconstituted with only two purified protein components, i.e., actinogelin and actin. Immunocompetition studies showed that actinogelin and gizzard alpha-actinin partially shared antigenicity, and their molecular shape and peptide maps were similar. Their amino acid compositions [Kuo et al., 1982], subunit and domain structures, and binding sites on actin [Mimura and Asano, 1987] are also very similar. Therefore, it is concluded that actinogelin belongs to alpha-actinin superfamily proteins. Furthermore, the presence of functionally different subfamilies concerned with Ca2+ sensitivity, gelation-efficiency, and others is discussed. Actinogelin, which induces networks of actin filaments, may be classified as high gelation type.

Actinin↗
PubMed1987

Further characterization of a conserved actin-binding 27-kDa fragment of actinogelin and alpha-actinins and mapping of their binding sites on the actin molecule by chemical cross-linking.

A conserved actin-binding domain (Mr = 27,000) of rat hepatic actinogelin, rat skeletal muscle, and chicken gizzard alpha-actinins (Mimura, N., and Asano, A. (1986) J. Biol. Chem. 261, 10680-10687) was separated into two components having different isoelectric points (peptides A and B) by chromatofocusing. Thermolysin digestion of peptide A generated peptide B with concomitant loss of peptide A. Amino acid compositions and tryptic maps of peptides A and B also demonstrated that peptide A is a precursor of peptide B upon thermolysin digestion. All of peptides A and B retained the activity to bind with F-actin competitively to each other. By the gel-filtration method, it was also shown that the native actin-binding 27-kDa fragments are monomeric and globular. The non-actin-binding 50- or 53.5-kDa fragment of actinogelin/alpha-actinins was, however, found to be asymmetric and dimeric in the native state. Chemical cross-linking of the 27-kDa fragment with F-actin with a water-soluble carbodiimide produced at least four different complexes (I-IV). Chemical cleaving analysis of the cross-linked products (complexes I and II) indicated that the 27-kDa fragment possesses two possible binding sites on actin at the NH2-terminal residues 1-12 (for complex I) and at residues spanning 86-119 or 123 (for complex II).

Actinin↗
PubMed1987

A workplace-based case-control study of gastric ulcer among male municipal employees in Japan.

In order to detect risk factors of gastric ulcer among male workers in Japan, a workplace-based case-control study was conducted in a municipal government, using cases registered during 1981 to 1983 with individually matched controls. Statistically significant factors in univariate analysis were smoking, time interval from waking up to leaving home for job, meal time for supper, sleeping hours, anxiety, and gloomy feeling. Logistic analysis showed that among the above factors the significant relative risks were 11.9 (95% confidence interval: 1.6-89.4) for 1-9 cigarettes per day, 9.9 (2.6-37.7) for 10 cigarettes or more per day, and 5.3 (1.6-17.5) for gloomy feeling. These findings obtained among the male Japanese workers were almost consistent with those epidemiologic results in other developed countries that smoking and personality traits are major risk factors of gastric ulcer.

Adult↗
PubMed1987

[Three cases of adenocarcinoma of the lower esophagus and cardia showing marked regression after radiotherapy with FT-207].

Three cases of adenocarcinoma of the lower esophagus and cardia which is considered to be difficult to control by radiotherapy alone, were given radical irradiation combined with FT-207 suppository. Dosages of radiation and FT-207 were 70 Gy/35 f and 1.5 g/day (1 case) or 1.0 g/day (2 cases), respectively. The treatment was successful locally; dysphagia was improved in all cases and 1 case has shown no recurrence for a period of two and a half years. Side effects were leukopenia and hemorrhagic esophagitis in the case given 1.5 g/day of FT-207, but these were cured by conservative therapy. These results emphasize that radiotherapy combined with anticancer drugs should be considered as a local therapy for inoperable adenocarcinoma of the lower esophagus and cardia.

Adenocarcinoma↗
PubMed1987

The long-term prognosis of patients gastrectomized for benign gastroduodenal diseases.

To study the long-term prognosis after gastrectomy, a total of 6,662 gastrectomized patients who had been operated on for benign gastroduodenal diseases between 1965 and 1980 were followed up from September 1, 1984 to May 30, 1986. The final vital status for the observed period could not be confirmed in 493 patients (7.4%), giving a follow-up rate of 92.6%. The average observation period was 13.1 years. The mortality from total deaths was almost identical to that of the general population adjusted for sex, age, and time trends of mortality, except for lower mortality among males in the first five years after operation. The risk of cancer mortality at all sites was lower than that of the general population, mainly due to the lower mortality from stomach cancer. This trend was not affected either by the type of gastroduodenal disease or by the method of operation. However, lung cancer mortality among males was significantly higher and one of the reasons for that could be excess smoking by males.

Alcohol Drinking↗
PubMed1987

Smoking, alcohol drinking and serum carotenoids levels.

Serum carotenoids concentrations in healthy inhabitants, aged 40-79 years, of a community were measured. The results are as follows. 1. The alpha- and beta-carotene and lycopene levels in serum were significantly higher in females than males. The alpha- and beta-carotene concentrations tended to increase with advancing age, this being especially marked for serum beta-carotene levels in males. However, beta-carotene levels were high in females throughout the age range of 50-69 years. There was no significant change in serum level of lycopene with age. 2. There was no significant difference in intake frequency of foods containing large amounts of carotenoids among the groups with or without smoking and drinking, as serum alpha- and beta-carotene levels were closely associated with intake frequency of green-yellow vegetables. 3. Regular alcohol drinkers or current smokers showed lower serum beta-carotene concentrations, and the effect of alcohol drinking on serum carotene level seemed to be larger than that of smoking. A synergistic lowering action of smoking and drinking on serum beta-carotene level was suggested. Among the alcohol drinkers, the more cigarettes consumed per day, the lower the serum beta-carotene level was, but this was not the case among the non-drinkers. Ex-smokers showed intermediate values between current smokers and non-smokers. The results suggest that alcohol drinking and smoking habit might be associated with lower serum beta-carotene level, which in turn may be related to excess incidence of cancer among smokers or drinkers.

Adult↗