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Biomedical subjects

Y Sakamoto

Publications and source records attributed to Y Sakamoto.

At least 703 records · Page 39Linked to original sources
PubMed1983

Full and empty particles of hepatitis B virus in hepatocytes from patients with HBsAg-positive chronic active hepatitis.

Complete and defective hepatitis B virus (HBV) particles in sera and hepatocytes were observed by electron microscopy for an understanding of the maturation process of hepatitis B virus. To distinguish Dane particles with or without DNA on the basis of staining density with uranyl acetate, Dane particles, purified from sera of asymptomatic carriers, and Dane particle cores, separated by ultracentrifugation in a metrizamide density gradient, were observed by electron microscopy. Complete cores at a low density (1.19 to 1.23 gm/cm3) were electron dense and incomplete cores at a high density (1.23 to 1.27 gm/cm3) were partially electron dense or empty. These findings demonstrated that the presence or absence of DNA is reflected by the electron density of the core. Our result, in which less than 10% serum Dane particles have full cores in ultrathin sections of the pellet, is in agreement with Gerin's finding that defective Dane particles are predominent in sera. Naked core particles and Dane particles in two biopsy specimens from patients with hepatitis B surface antigen, hepatitis B e antigen, and DNA polymerase-positive, chronic active hepatitis were classified into complete versus incomplete particles on the basis of electron density. Nine hundred and fourteen naked core particles were detected in nuclei and cytosol of 68 hepatocytes. One hundred and five core particles (11.5%) were electron dense and 809 core particles (88.5%) were partially electron dense or empty. Furthermore, 488 Dane particles were observed in the cisternae of the endoplasmic reticulum of these hepatocytes. Fifty Dane particles (10.2%) had full cores, and 438 Dane particles (89.8%) had partially full or empty cores. These findings suggest that DNA may be incorporated into about 1 to 10% of core particles when they are assembled in nuclei of hepatocytes. Morphologic differences in damage to hepatocytes containing various frequencies of full Dane particles were also studied, but no significant correlation was found between damage in hepatocytes and frequency of full Dane particles.

Hepatitis B Surface Antigens↗
PubMed1982

Changes in antibody titers in cattle infected clinically and subclinically with bovine leukemia virus.

Changes in titers of antibodies to protein and glycoprotein antigens of bovine leukemia virus (BLV) were investigated by immunodiffusion in two groups of cattle. In one group of cattle (10 head) which developed enzootic bovine leukosis during the observation period of 3 years, seven showed a gradual increase in antibody titers following a period of level antibody titers that persisted for several months to several years. The titer was finally eight to 32 times higher than the initial titer. The remaining three showed little change in titer. Of the 10 animals with tumors, three showed a decrease in the titer when they were in extremis. In contrast, in the second group of cattle (110 head), which were infected with BLV subclinically, the change in the titers during 1 and 3 years ranged from no change to four times the lowest titer that was observed during the period. Of the cattle which had a low level of antibody to one of the BLV antigens, a few became negative reactors to the respective antigen.

Animals↗
PubMed1982

Diminution of chemically induced lung neoplasia in mice by phenobarbital pre-treatment.

Pre-treatment of 21-day-old ICR/Jcl mice with 75 micrograms/g of phenobarbital significantly reduced the yields of lung tumors induced by 4-nitroquinoline-1-oxide (4NQO) and furylfuramide. Dimethylbenz[a]anthracene (DMBA)- and urethane-induced lung tumorigenesis was also reduced, but was not significantly different from that in mice receiving only the carcinogen. However, 6 consecutive treatments with phenobarbital (40 micrograms/g) in adult mice greatly reduced urethane-induced lung tumorigenesis. Post-treatment with an equal dose of phenobarbital showed neither diminution nor enhancement of tumorigenesis.

4-Nitroquinoline-1-oxide↗
PubMed1982

The L-methionine-sparing effect of dietary glutathione in rats.

The availability of cysteine moiety released from dietary glutathione (GSH) for protein synthesis in rats was studied to determine the L-methionine-sparing effect of this peptide. Animals were fed diets containing 18% of an amino acid mixture having a composition similar to that of whole egg, with or without GSH. The proportions of L-methionine, L-cysteine and GSH in the diet were varied, and one of these components was labeled with 35S. The incorporation of label into proteins and GSH in the liver and into proteins in the plasma was determined to assess the utilization of the sulfur atoms in these sulfur-containing substances. Dietary [35S]GSH was found to be incorporated efficiently into proteins and GSH in the liver and into plasma proteins. The results demonstrate the L-methionine-sparing effect of dietary GSH, in terms of incorporation Of its 35S into proteins and GSH. GSH spared L-methionine almost as efficiently as L-cysteine in plasma protein synthesis, though slightly less in liver protein synthesis. The effect of GSH increased with increase in its concentration in the diet.

Animals↗
PubMed1982

The complete amino acid sequence of human P2 protein.

The complete amino acid sequence of P2 protein from human peripheral nerve myelin was determined from nine staphylococcal protease peptides and four cyanogen bromide peptides. Human P2 protein is composed of 131 amino acids and has a molecular weight of 14,818. Compared to bovine P2 protein, there are replacements at nine positions (human in equilibrium bovine): 18(Asp in equilibrium Glu), 39(Thr in equilibrium Arg), 56(Thr in equilibrium Pro), 83(Ile in equilibrium Thr), 87(Gln in equilibrium Ala), 96(Arg in equilibrium Lys), 100(Lys in equilibrium Asn), 115(Ala in equilibrium Val), and 121(Gly in equilibrium Asp).

Amino Acid Sequence↗
PubMed1982

Depolarization produced by sodium removal in the circular muscle of the guinea-pig stomach.

1. Reducing the Na concentration to less than 20 mM depolarized the circular muscle of the guinea-pig stomach and contracture developed. The rate of depolarization varied between preparations. In some, all electrical activity disappeared within 2-3 min in Na-free solution, accompanied by depolarization, but in other preparations a sinusoidal rhythmic activity remained for various lengths of time up to 10 min. 2. When Ca was removed after the depolarization in Na-free solution was fully developed, the membrane partly repolarized and the contracture was abolished. Addition of 2 mM-Mn in the presence of Ca had the same effect. 3. After complete block of electrical activity in Ca-free and Na-free solution, readmission of only Ca (2.5-50 mM) produced sinusoidal rhythmic activity. This activity, observed in the absence of Na, was abolished when the membrane was hyperpolarized by applying inward current. 4. The membrane depolarized in Na-free solution was repolarized by readmission of only 5 mM-Na. This repolarization was greater and faster when the exposure to Na-free solution was prolonged. 5. The possibility was considered that an electrogenic Na-Ca exchange may be involved in the generation of the first component of the slow wave, and that removal of Na blocked the repolarizing phase of this component. In the absence of Na, Ca can evoke rhythmic activity and the underlying mechanism may be the same as that of the second component of slow wave, i.e. an increase in Ca conductance.

Animals↗
PubMed1982

[Comparative study on cefmetazole and cefazolin in the treatment of suppurative otitis media].

Cefmetazole (CMZ) was compared to cefazolin (CEZ) for efficacy and safety in the treatment of suppurative otitis media (including acute otitis media and chronic otitis media in acute aggravating stage) under well controlled clinical trials. The therapeutic effects were analyzed statistically in 172 patients (82 administered CMZ, 90 administered CEZ). The adverse reactions were also analyzed statistically in 199 patients (CMZ 99, CEZ 100) in whom the judgement was possible. 1. The efficacy rate of CMZ (72.3% for good to excellent response) was assessed by physicians in charge to be similar to that of CEZ (59.3%). This was the same being assessed by the committee, too (CMZ 64.6%, CEZ 56.7%). 2. When patients were classified into 2 groups (acute otitis media, chronic otitis media in acute aggravating stage) with respect to diagnosis, statistically significant difference in clinical efficacy assessed by physicians in charge was observed in the cases with chronic otitis media (CMZ, CEZ). In addition, the improvements of flares on the drum membrane and the mucous membrane of eardrum were significantly better in the CMZ group than in the CEZ group. 3. Bacteriologically, 16 cases (19.8%) of S. aureus were resistant to CEZ, while only 1 case (1.2%) to CMZ. CMZ was judged to be effective in 5 of the 6 cases in which CEZ-resistant strains were detected. 4. Side effects were found in 2 cases (2.0%) treated with CMZ: one complained of retching and abdominal pain and the other developed skin eruption. On the other hand, only 1 case (1.0%) developed skin eruption in the CEZ group. These results suggest that CMZ is a new antibiotic agent which is highly valuable in the treatment of suppurative otitis media.

Adolescent↗
PubMed1982

Electron and immunoelectron microscopic study of Dane particle formation in chronic hepatitis B virus infection.

The site of Dane particle formation in hepatocytes was studied by routine electron and immunoelectron microscopy of liver biopsy specimens from 10 patients with hepatitis B e antigen-positive chronic active hepatitis. With routine electron microscopy, core particles were abundant in cytosol, often adjacent to the cell membrane, and occasionally in the microvilli. Figures suggestive of budding of endoplasmic reticulum with a core particle into the cisternae of endoplasmic reticulum were observed frequently. There were also figures suggestive of direct budding with a core particle from the surface of the cell. With the immunoelectron microscopy, the core particles were found to be positive for hepatitis B core antigen and the endoplasmic reticulum and the plasma membrane were positive for hepatitis B surface antigen. These findings suggest that the most plausible mode of formation of the Dane particle is by budding of hepatitis B surface antigen-positive endoplasmic reticulum membrane into the cisternae. In addition, formation of the Dane particle may also take place at the surface of the hepatocyte by a similar mechanism.

Cell Membrane↗