Search PubMed⌕ Search

Biomedical subjects

T Miyazaki

Publications and source records attributed to T Miyazaki.

At least 541 records · Page 30Linked to original sources
PubMed1992

G test, a new direct method for diagnosis of Candida infection: comparison with assays for beta-glucan and mannan antigen in a rabbit model of systemic candidiasis.

An indirect method to measure beta-glucan, a major structural component of yeast cell walls, is available, but has the disadvantage of requiring the combined use of two assays. Recent reports describe the fungal index, which measures the difference between the conventional limulus test, in which factors C and G react with endotoxin and beta-glucan, and a new endotoxin-specific test, in which only factor C reacts with endotoxin. The G test was developed as a direct method to measure beta-glucan, and contains only factor G reacting with beta-glucan alone. In this study, the G test was examined in sera of rabbits with experimental systemic candidiasis, and compared with the fungal index and mannan assay. The G test showed positive in all rabbits with systemic candidiasis faster and with higher titers than with the fungal index. Three rabbits with fulminant systemic candidiasis showed higher levels of reactivity with the G test and the fungal index than two rabbits with mild reactions. Mannan was positive by at least one serum in four of five rabbits by the latex agglutination test, and there was a good correlation between these assays. The G test is a good serodiagnostic method for the detection of candidiasis.

Animals↗
PubMed1992

Phenytoin partially antagonized L-type Ca2+ current in glucagon-secreting tumor cells (ITC-1).

Transmembrane Ca2+ currents were investigated by means of a whole-cell clamp technique in a hamster glucagon-secreting tumor cell line (ITC-1). Two types of Ca2+ current were identified in ITC-1 cells. The low-threshold and transient (T-type) current became detectable above the potential level around -60 mV and decayed rapidly with an inactivation time constant of 95 ms (at -40 mV and 23 degrees C), while the high-threshold and long-lasting (L-type) one was activated by depolarization more positive to -30 mV with non-inactivating kinetics. The voltage dependence and kinetics of these currents were identical to those reported in guinea-pig pancreatic alpha 2 cells. Both currents were augmented by equimolar substitution of Ca2+ with Ba2+ and completely abolished by adding 1 microM La3+. Phenytoin, a well known anti-epileptic drug and a postulated T-type specific Ca2+ current antagonist, surprisingly blocked the L-type current without affecting the T-type current in ITC-1 cells. While phenytoin antagonized the L-type Ba2+ current selectively, 60% of the current remained even in supramaximal concentration range over 500 microM. The residual component of the L-type current was completely abolished by adding nifedipine.

Animals↗
PubMed1992

Interpretation of COHb concentrations in the left and right heart blood of cadavers.

Carbon monoxide hemoglobin (COHb) concentrations in left and right heart blood samples from cadavers both exposed and not exposed to fire or CO gas were analyzed by the gas chromatographic method. The COHb concentration ratio between samples of left and right heart blood (L/R ratio) does not appear to be useful for establishing whether death has occurred before or after exposure to fire with the exception of cases where no soot can be detected in the airways by the naked eye and the COHb concentration in the blood sample is within the level considered normal for tobacco smokers.

Adolescent↗
PubMed1992

Relationship of Helicobacter pylori to serum pepsinogens in an asymptomatic Japanese population.

A seroepidemiologic study of the prevalence of Helicobacter pylori infection in Japan was performed, and the relationship between serum pepsinogen I and II levels (markers of gastritis and gastric atrophy) and H. pylori infection was investigated. Four hundred and eighteen asymptomatic children and adults were studied. The prevalence of anti-H. pylori immunoglobulin G antibody increased with age. For persons born after 1950, the frequency of H. pylori infection increased at approximately 1% per year; for those born before 1950 the prevalence was high (70%-80%) and relatively constant. Serum pepsinogen I and II levels were significantly higher in H. pylori-infected volunteers than in H. pylori-uninfected volunteers [51.6 +/- 3 vs. 42.9 +/- 2 ng/mL (P less than 0.05) for pepsinogen I; 16.0 +/- 1 vs. 7.5 +/- 0.8 ng/mL (P less than 0.001) for pepsinogen II]. The ratio of pepsinogen I to pepsinogen II was significantly lower in H. pylori-infected volunteers (3.5 +/- 0.2) than in uninfected volunteers (6.3 +/- 0.3; P less than 0.001). The apparent decrease in prevalence of H. pylori accompanying the Westernization of Japan may eventually be accompanied by a reduction in the frequency of atrophic gastritis, the precursor lesion of the epidemic form of gastric carcinoma, and ultimately result in a decrease in the incidence of gastric carcinoma in Japan.

Adolescent↗
PubMed1992

Proteolytic processing sites producing the mature form of human cathepsin D.

1. The proteolytic processing sites of human lysosomal aspartic protease cathepsin D at which the intermediate single-chain form was converted into the mature two-chain form were determined. 2. The two chains were isolated by reversed-phase HPLC in order to investigate the cleavage sites of the enzyme. 3. Protein sequencing of the heavy chain, which was presumed to be derived from the C-terminal side in the single-chain enzyme, gave an N-terminal Leu 105. In addition, it revealed that there were also minor sequences, which commenced with Gly 106 and Gly 107. 4. A small C-terminal peptide was isolated from the light chain, which had been digested with two kinds of exogenous proteases. Sequence determination of this peptide, which was characterized as a nonapeptide by mass spectrometry, suggested that the C-terminus of the light chain was Ser 98. 5. These results indicate that a Ser 98-Ala 99 bond and an Ala 104-Leu 105 bond are cleaved to release 6 amino acid residues between the two chains.

Amino Acid Sequence↗
PubMed1992

Complete prevention of diabetes in transgenic NOD mice expressing I-E molecules.

Previously, we showed that transgenic expression of the MHC (major histocompatibility complex) class II I-E molecules prevented insulitis in non-obese diabetic (NOD) mice at the age of 19 weeks. To rule out the possibility that the I-E expression merely delays the onset of insulitis, we have further characterized the expression and function of the I-E molecule expressed in transgenic NOD mice and confirmed our previous observations. Northern blot analysis showed that the transgenic E alpha d gene was expressed in a pattern similar to the endogenous E alpha d gene in BALB/c mice. The newly expressed I-E molecules were recognized as an alloantigen by the T lymphocytes of normal NOD mice as shown by mixed lymphocyte reaction (MLR). Transgenic NOD mice were resistant to the treatment by cyclophosphamide, which effectively induces diabetes in normal NOD mice, and did not develop diabetes up to 40 weeks of age. On the basis of these findings, we discuss the role of I-E molecules in the prevention of diabetes in NOD mice.

Animals↗
PubMed1992

Identification of polymerized-albumin receptor domain in the pre-S2 region of hepatitis B virus surface antigen M protein.

The pre-S2-coding region in the hepatitis B virus surface antigen M (P31; pre-S2 + S) protein gene was modified to identify a polymerized-albumin receptor (PAR) domain by deleting restriction fragments or performing site-directed mutagenesis. The modified M protein genes (M-P31x; x = d, e, f, h and i) were cloned into the yeast generalized-expression vector pGLD 906-1 and expressed in Saccharomyces cerevisiae under the control of yeast glyceraldehyde-3-phosphate dehydrogenase gene promoter. The PAR activities of these gene products suggested that the PAR domain is located in the hydrophilic and highly conserved domain in the pre-S2 region (around Leu12 approximately Tyr21). Antibodies specific for a pre-S2 peptide (Phe8 approximately Pro34, subtype adr), which covers the PAR domain, were purified from sera of rabbits immunized with yeast-derived M protein particles having a natural PAR domain. Immune electron microscopy showed that the purified antibodies could aggregate HBV particles. Therefore, it was speculated that the PAR domain overlapped with the dominant virus-neutralizing and virus-protecting epitopes.

Amino Acid Sequence↗
PubMed1992

Transgenic mouse as a tool for the study of autoimmune disease: insulin-dependent diabetes mellitus.

Transgenic mice have been used for analyses of cis-acting elements which are involved in the tissue-specific and developmental-specific expression, for analyses of physiological function of genes, or for the production of a human disease model. This approach is especially successful in the fields of immunology and oncology. Several years ago it was shown that the major histocompatibility complex (MHC) class II gene is identical to the immune response gene by demonstrating that the immune response can be restored by the new expression of class II molecules on immunocompetent cells. Recent evidence suggests that the class II molecule is involved in the generation of autoimmune disease, such as insulin-dependent diabetes mellitus (IDDM). The NOD (non-obese diabetic) mouse is shown to be a mouse model for human IDDM. Concerning the class II genes, the NOD mouse has two characteristic features, the lack of I-E and the presence of unique I-A. It is discussed how the role of class II molecules in the development of IDDM in the NOD mouse can be analyzed. In addition, the transgenic technique can be applied to the study of differentiation and oncogenesis of lymphoid cells. Factors or molecules that affect these processes will also be discussed.

Animals↗
PubMed1992

Discrepancy between estimated and actual time elapsed after death of a severed head.

A severed head which had been wrapped in seven plastic bags and set in concrete in an airtight insulated plastic box was found approximately 22 months after the occurrence of death. Ammonium magnesium phosphate had formed and on the basis of this and other observed postmortem changes, time elapsed after death was estimated to be from 2 weeks to 6 months. The absence of oxygen is thought to have contributed significantly to the great discrepancy between estimated and actual time elapsed after death.

Adult↗
PubMed1992

Stress-induced gastric mucosal lesion and platelet aggregation in rats.

The effect of cold-restraint stress on platelet function in vitro was studied in the rat model. Platelet function was assessed by platelet aggregation in response to adenosine diphosphate (ADP) and thrombin. ADP-induced platelet aggregation was reduced in platelet-rich plasma after 2 h of cold-restraint stress. Thrombin-induced platelet aggregation was reduced with time during cold-restraint stress with a parallel increase in the lesion index. Although pretreatment of animals with atropine prevented the development of gastric mucosal lesions, platelet dysfunction was not reversed by this treatment. These results suggest that cold-restraint stress may impair platelet function, probably due to platelet activation in vivo, and that the abnormalities in platelet function may be associated with the development of gastric mucosal lesions.

Adenosine Diphosphate↗
PubMed1992

[Limulus test (factor G) and polysaccharides from fungus].

Picogram quantifies per ml of endotoxin showed a positive limulus test. The concentration more than ten pg/ml of curdlan ((1-3)-beta-D-glucan) was also positive to a conventional limulus test, which contains a factor G. One nanogram per ml of CM-curdlan was positive, but higher concentration of 10 pg/ml of CM-curdlan decreased its optical density of the conventional limulus test. More than one hundred ng/ml of mannan from Saccharomyces cerevisiae did not react with factor G. However, a culture supernatant of Saccharomyces cerevisiae activated factor G. This result suggested that beta-glucan activated factor G. In addition, culture supernatant of Aspergillus fumigatus, Rhodotorula rubra, Candida parapsilosis, Candida tropicalis, Candida krusei also activated factor G, but Cryptococcus neoformans did not activate it.

Antimicrobial Cationic Peptides↗
PubMed1992

DNA sequence analysis of the dnaK gene of Escherichia coli B and of two dnaK genes carrying the temperature-sensitive mutations dnaK7(Ts) and dnaK756(Ts).

The DNA sequence of the dnaK gene of Escherichia coli was analyzed. The nucleotide sequence of the wild-type dnaK gene of E. coli B differed from that of E. coli K-12 in 15 bp, none of which altered the amino acid sequence. Two temperature-sensitive dnaK mutations were examined by cloning and sequence analyses. Results showed that one dnaK mutation, dnaK7(Ts), was a one-base substitution of T for C at nucleotide position 448 in the open reading frame yielding an amber nonsense codon. The other mutation, dnaK756(Ts), consisted of base substitutions (A for G) at three nucleotide positions, 95, 1364, and 1403, in the open reading frame resulting in an aspartic acid codon in place of a glycine codon.

Amino Acid Sequence↗
PubMed1992

Synaptic mechanisms in sympathetic preganglionic neurons.

Intracellular recordings from sympathetic preganglionic neurons (SPNs) in adult cat and neonatal rat spinal cord slices reveal four types of synaptic potentials, namely, excitatory postsynaptic potentials (EPSPs), inhibitory postsynaptic potentials (IPSPs), and slow EPSPs in both preparations, and a slow IPSP in cat SPNs. Pharmacological studies show that glutamate or a related excitatory amino acid and glycine are the probable mediators of EPSPs and IPSPs. There may be heterogenous mediators of slow EPSPs; substance P, serotonin, norepinephrine, and epinephrine are all probable mediators of slow EPSPs in subpopulations of SPNs. In the case of slow IPSPs, norepinephrine appears to be the likely transmitter. Finally, stimulation of ventral roots elicits a synaptic potential that appears to be caused by glutamate released from afferent fibers in the ventral roots. Our results indicate that a multitude of synaptic mechanisms exist in the rat SPNs by means of which inputs arising from sensory and supraspinal neurons are processed in a timely and orderly manner, thus ensuring highly organized but differentiated outputs to multiple peripheral target cells.

Animals↗
PubMed1992

Suppressed serum and urine levels of indoxyl sulfate by oral sorbent in experimental uremic rats.

In uremic patients, the serum concentration of indoxyl sulfate is markedly increased. To determine if oral sorbent (AST-120) suppresses the endogenous synthesis of indoxyl sulfate, it was administered to experimental uremic rats, and the serum concentration and urinary excretion of indoxyl sulfate were quantified by high-performance liquid chromatography. Oral sorbent decreased both the serum concentration and urinary excretion of indoxyl sulfate, suggesting that there was suppression of the endogenous synthesis of indoxyl sulfate by the oral sorbent. Oral sorbent did not decrease the serum concentration and urinary excretion of hippuric acid, but it did alleviate the deterioration of renal function in the experimental uremic rats.

Adsorption↗
PubMed1992

Physicochemical characteristics and antitumor activities of a highly branched fungal (1----3)-beta-D-glucan, OL-2, isolated from Omphalia lapidescens.

Physicochemical properties and antitumor activities of a fungal (1----3)-beta-D-glucan, OL-2, isolated from Leiwan (Omphalia lapidescens) were examined. OL-2 showed sharp signals on carbon-13 nuclear magnetic resonance spectrum in dimethylsulfoxide-d6 as a solvent, and these signals were significantly reduced by the addition of distilled water to the concentration of 20%. This phenomenon is consistent with the general property of the gel forming (1----3)-beta-D-glucan. Binding of OL-2 to Congo red induced a significant change of lambda max to a longer wavelength, and the concentration to induce gel to sol transition was about 0.7 N; in contrast, the concentration was about 0.2 N in the cases of SPG and curdlan. These observations suggested that the gel structure would be significantly stabilized in the case of OL-2. OL-2 showed no or low antitumor activity against the solid form of Sarcoma 180 by intraperitoneal and intralesional administrations; however, it was effective on the ascites form of Sarcoma 180. Of interest, OL-2 also showed significant antitumor activity against the ascites form of MH-134 when administered with 5-fluorouracil. These results indicated that OL-2 showed characteristic features regarding its physicochemical properties and antitumor activity.

Agaricales↗
PubMed1992

Structure and antitumor activity of the less-branched derivatives of an alkali-soluble glucan isolated from Omphalia lapidescens. (Studies on fungal polysaccharide. XXXVIII).

The structure and antitumor activity of Smith-type degradation products (OL-2-I, OL-2-II and OL-2-III) of an alkali-soluble glucan, OL-2, isolated from a crude fungal drug "Leiwan" (Omphalia lapidescens) were investigated. Methylation analysis suggested that OL-2-I was a (1----3)-beta-D-glucan with approximately one branch at every three main chain glucosyl units at each C-6 position; OL-2-II was a (1----3)-beta-D-glucan with approximately one branch at twenty four main chain glucosyl units at each C-6 position (number of all main chain glucosyl units is on average). OL-2-I, OL-2-II and OL-2-III which were Smith-type degradation products of OL-2, showed potent antitumor activity against the solid form of sarcoma 180 in ICR mice. These results indicated that the degree of beta-linked branching at position 6 was remarkably related to the antitumor activity.

Agaricales↗