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Biomedical subjects

T Kamimura

Publications and source records attributed to T Kamimura.

At least 145 records · Page 8Linked to original sources
PubMed1987

Studies on transmission of human non-A, non-B hepatitis to marmosets.

Two sera obtained from four healthy blood donors, which caused non-A, non-B post-transfusion hepatitis in two recipients, were experimentally inoculated into nine marmosets. Three of seven marmosets developed acute hepatitis characterized by the elevation of serum concentrations of glutamic pyruvic transaminase (GPT) and/or isocitric dehydrogenase (ICD) 8-11 weeks after inoculation. Four of seven showed histopathological changes of acute hepatitis in liver biopsy specimens during the biochemically acute phase. In electron microscopic examination, attached membrane-like structures, which consisted of two-unit membranes of two neighboring endoplasmic reticula with electron-dense material between them, were noted in cytoplasm of hepatocytes during the acute phase of hepatitis. Furthermore, acute-phase sera obtained from two animals were inoculated into four additional marmosets, and non-A, non-B hepatitis was successfully passaged in two of them. The results of this study indicate that certain species of marmoset monkeys are susceptible to human non-A, non-B hepatitis agents and provide a useful animal model for non-A, non-B hepatitis.

Alanine Transaminase↗
PubMed1987

Ultrastructural findings on polymorphonuclear leucocyte infiltration and acute hepatocellular damage in alcoholic hepatitis.

Ultrastructural examination was carried out in 13 liver biopsies from patients with alcoholic hepatitis, with special reference to the relationship between alcoholic hyaline (AH)-containing hepatocytes and inflammatory cell infiltration. In as many as one third of the cases, polymorphonuclear leucocyte (PMN) migration into the cytoplasm of AH-containing hepatocytes was noted. The migrating PMNs often had discontinuous cell membranes and their primary and secondary granules were demonstrated to be released into the liver cell cytoplasm. Finally, migrating PMNs appeared collapsed and dying. These PMNs appeared to gather around AH, presumably due to the strong chemoattractive action of AH. The hepatocytes invaded by PMNs revealed various degrees of degeneration and cell necrosis. Occasionally, some lymphocytes infiltrated into hepatocytes and had a direct contact with AH. However, the occurrence of lymphocyte migration was much less than that of PMNs. Kupffer cells were also intermingled with these PMNs and often possessed AH in degraded forms in their phagosomes or phagolysosomes. Based on these results, it is postulated that acute hepatocellular damage in patients with alcoholic hepatitis might be caused by this peculiar type of degranulation and collapse of migrating PMNs against AH-containing hepatocytes in addition to the various causes previously studied.

Cell Survival↗
PubMed1986

Experimental studies on mechanism of the Menière's attack: investigation into vestibulo-cochlear response of the guinea pig induced by potassium ion.

After introducing potassium ion through the round window into the perilymphatic space of 40 guinea pigs by means of iontophoresis, physiological and histochemical investigations were performed to determine the role of the high perilymphatic potassium concentration in the vertiginous attack of Ménière's disease. About 15 min after the iontophoretic procedure, electronystagmography revealed irritative nystagmus for the first 5 min and then paralytic nystagmus for the following 6 to 24 hr. Histochemical analysis of the vestibular sensory epithelia revealed the increased activity of succinic dehydrogenase and Na-K-ATPase during irritative nystagmus and the decreased activity during paralytic nystagmus. The Na-K-ATPase activity was dominant in the synaptic area between the hair cells and the nerve-endings of the vestibular sensory epithelia. There was some delay between the reversal of nystagmus-direction and the change of enzyme activity. This delay was thought to be produced by the central regulatory mechanism for the disturbed tonus-balance in the vestibular nucleus. On the other hand, electrocochleography revealed the decrease of the action potential without any initial irritative cochlear sign, and the enzyme activity of the cochlear sensory cells was decreased from the beginning.

Animals↗
PubMed1986

Studies on beta-lactam antibiotics. X. Synthesis and structure-activity relationships of 7 beta-[(Z)-2-(2-amino-4-thiazolyl)-2-(carboxymethoxyimino)acetamido] cephalosporin derivatives.

The synthesis of 7 beta-([Z) -2-(2-amino-4-thiazolyl)-2-(carboxymethoxyimino) acetamido]-cephalosporins (2a-h) modified at the C-3 position of a cephem nucleus and the effect of the C-3 substituents on the antibacterial activity, oral absorptivity and therapeutic activity are discussed. The cephems (2a and 2b) having a C-3 substituent such as hydrogen or vinyl were more potent than other cephalosporins against Gram-negative bacteria. However, the cephalosporin (2f) having methylthio group at the 3-position showed the highest absorption rate in rats. These three cephalosporins (2a, b and f) exhibited equally good protective activities in mice infected. Furthermore, the serum levels of these cephalosporins (2a, b and f) were examined in dogs, and 2b and 2f showed outstanding high and prolonged serum levels.

Administration, Oral↗
PubMed1985

Localization of hepatitis A virus in marmoset liver tissue during the acute phase of experimental infection.

Electron microscopic and virological studies of marmoset liver tissue with acute infection of hepatitis A virus (HAV), especially in the earlier stages of infection, were carried out to characterize the maturation process of HAV. Four marmosets were inoculated intravenously with HAV suspension and sacrificed 1 week, 2 weeks, 3 weeks and 4 weeks after inoculation respectively. Hepatitis A antigen (HAAg) in 10% liver homogenates of marmosets was examined by radioimmunoassay and a large amount of HAAg was detected in the liver homogenate of two marmosets sacrificed 2 weeks and 3 weeks after inoculation respectively. The histodiagnosis of the marmoset sacrificed 2 weeks after HAV inoculation was normal. However, many clusters of virus-like particles about 27 nm in diameter, in both "solid" and "empty" forms were found, mainly in vesicles of Kupffer cells by electron microscopy. In the animal that developed mild hepatitis 3 weeks after inoculation HAV-like particles were found in vesicles of hepatocytes by electron microscopy. By immune electron microscopy using peroxidase-conjugated anti-hepatitis A antibody, HAAg was detected on the particles present within the cytoplasmic vesicles of Kupffer cells or hepatocytes and on the surrounding membrane of the vesicles which contained HAV-like particles.

Alanine Transaminase↗
PubMed1985

Inhibition of delayed hypersensitivity reactions by a new agent, cis-1-methyl-4-isohexylcyclohexane carboxylic acid (IG-10).

A newly synthesized compound, cis-1-methyl-4-isohexylcyclohexane carboxylic acid (IG-10), has been reported as an inhibitor of delayed hypersensitivity reaction. In the present paper, the mechanisms regarding the inhibitory action of IG-10 was investigated on delayed hypersensitivity reactions. p-Phenylenediamine-induced contact dermatitis in guinea pigs was significantly inhibited when the drug was given in a dose of 100 mg/kg p.o. at various times after challenge with the antigen. IG-10 inhibited both contact dermatitis and monocytes or neutrophils infiltrations induced by picryl chloride in mice. A skin reaction, similar to that seen in the case of delayed hypersensitivity reaction, was induced by an intradermal injection of phytohemagglutinin-P (PHA-P) stimulated lymphocytes in guinea pigs. This reaction was a useful method for assessing the effect of drugs on the release of lymphokines, particularly skin reactive factor (SRF). IG-10 in a concentration of 10(-5) g/ml inhibited the release of SRF as well as the release of migration inhibitory factor (MIF) from guinea pig lymphocytes stimulated by PHA-P. The reduction of delta 4-3-ketone of aldosterone and/or hydrocortisone by rat liver homogenates was not affected with IG-10, unlike that seen in the case of glycyrrhizin.

Aldosterone↗
PubMed1985

Chemical synthesis of capped RNA fragments and their ability to complex with eukaryotic ribosomes.

In other to examine the binding ability of the 5'-terminal part of eukaryotic mRNA to 80S ribosome, several kinds of oligoribonucleotides, pA-U-G, m7G5'pppA-U-G, m7G5'pppG-U, m7G5'pppA-U-G-A-C-C, were synthesized chemically. The binding experiments of oligonucleotides to 80S ribosome showed that the capped structure as well as AUG are essential for ribosome binding, and the efficiency is enhanced by the 5'-leader sequence if it would include complementary sequence to the 3'-terminal part of 18S rRNA.

Base Sequence↗
PubMed1984

Studies by immune electron microscopy of hepatitis B surface antigen in PLC/PRF/5 cells.

Electron microscopic studies of the morphology of hepatitis B surface antigen (HBsAg) produced by PLC/PRF/5 cells in vitro were carried out. Aggregates of 20-nm spherical particles in 3-day culture supernatants were observed by immune electron microscopy (IEM). Aggregates of tubular structures were found with IEM in the extracts of the cells. Tubular structures 18 to 22 nm in diameter were seen by electron microscopy (EM) in the cisternae of the endoplasmic reticulum in 2-3% of the cells. The tubular structures in the cytoplasm and extracts of PLC/PRF/5 cells resembled those observed in the hepatocytes of human carriers of hepatitis B virus (HBV). Intracellular localization of HBsAg in PLC/PRF/5 cells by direct peroxidase-conjugated antibody staining was observed on the tubular structures and the cisternal wall, which contained these structures. Rotation technique analysis indicated that the tubular structures were composed of 11 or 12 subunits.

Carcinoma, Hepatocellular↗
PubMed1984

125I-glucagon-degrading activity in acid-saline extracts of rat salivary gland.

The antibody-binding ability of the glucagon-like substance in rat submaxillary gland acid saline extract was examined by affinity chromatography, and the biological activity studied using the isolated liver perfusion method. We found that the glucagon-like substances in acid saline extract could not be bound to anti-glucagon antibody and that the gel-filtration peak on ultrogel AcA 54 could increase neither glucose nor cyclic AMP output from isolated perfused rat liver. Furthermore, the radioactivity peak of 125I-glucagon on Bio Gel P-6 column chromatography moved from its original position and eluted in later fractions after incubation with an acid saline extract of the submaxillary gland. In consequence, there was 125I-glucagon degrading activity in the submaxillary gland, but no glucagon-related peptide. Therefore, it is suggested that the glucagon-like substance, which has been reported in acid saline extract of the rat salivary gland, may be an artifact due to tracer degrading activity.

Animals↗
PubMed1984

Synaptosomal localization and release of glucagon-like materials in the rat brain.

The subcellular localization of glucagon-like materials in the thalamus-hypothalamus and brain stem of the rat was investigated. Both glucagon immunoreactivity (GI) determined by C-terminal specific antibody and glucagon-like immunoreactivity (GLI) determined by non-specific antibody were enriched in the microsomal and synaptosomal fractions relative to the nuclear, myelin and mitochondrial fractions. Furthermore, the synaptosomal fraction of both the thalamus-hypothalamus and brain stem incubated in Krebs-Ringer bicarbonate buffer with 55 mM K+ at 37 degrees C released GI and GLI in the presence of Ca++. These findings suggested that glucagon-like substances detected in the brain have a role in the synaptic function.

Animals↗
PubMed1984

In vitro and in vivo antibacterial properties of FK 027, a new orally active cephem antibiotic.

FK 027 was more active than cefaclor, cephalexin, and amoxicillin against stock strains of a wide variety of gram-negative bacteria, including such opportunistic pathogens as Citrobacter and Enterobacter species and Serratia marcescens. FK 027 was significantly more active than the three reference drugs against clinical isolates of Escherichia coli, Klebsiella pneumoniae, indole-positive and -negative Proteus species, Providencia species, Haemophilus influenzae, and Neisseria gonorrhoeae. It was less active than cefaclor, cephalexin, and amoxicillin against staphylococci, but it was similar to cefaclor in its activity against streptococci. With few exceptions, FK 027 was active against strains of E. coli, K. pneumoniae, and Proteus mirabilis that were resistant to the reference agents. The bactericidal activity of FK 027 against various gram-negative bacteria, including Proteus species, Citrobacter freundii, Enterobacter aerogenes, and S. marcescens, was greater than that of cefaclor, cephalexin, and amoxicillin. The therapeutic activities of FK 027 in mice infected with gram-negative bacilli were far superior to the activities of cefaclor, cephalexin, and amoxicillin, but they were inferior to the activities of these reference drugs against infection with Staphylococcus aureus.

Amoxicillin↗
PubMed1984

Influence of long-term repetitive rotatostimulations on lateral semicircular canals.

Sixty-five guinea pigs were used to investigate the influence of rotatostimulations on the lateral crista ampullaris. After repeated turning stimulations with the cupulometric mode (the terminal turning velocity: 180 degrees/sec) for 24-72 hours, the morphological changes in the crista ampullaris on the ampullopetal flow side were compared with those on the ampullofugal flow side by using scanning and transmission electron microscopy. Postrotatory nystagmus recorded by ENG during this experiment revealed the response decline phenomenon in all animals, and the caloric test performed after the rotatostimulation showed 'canal paresis' in the ear on the ampullopetal flow side. In a group stimulated for 24 hours, no particular damage on the crista ampullaris was noticed. However, in a group stimulated for 72 hours, local damage was dominant in the central part of the crista, which showed a tendency to extend towards the planum semilunatum according to an increment of changes. These findings were more remarkable on the ampullopetal flow side than on the ampullofugal flow side, suggesting the predominant effect of the ampullopetal endolymph flow in the lateral semicircular canal.

Animals↗