Biomedical subjects

Y Yoshida

Publications and source records attributed to Y Yoshida.

At least 955 records · Page 53Linked to original sources

PubMed1992

Processing of hepatitis B virus surface antigen expressed by recombinant Oka varicella vaccine virus.

We have constructed a recombinant Oka varicella vaccine virus expressing hepatitis B virus (HBV) surface antigen (HBsAg). HBsAg was synthesized as 26K and 30K proteins in infected cells and secreted into the culture supernatant as 30K and 35K proteins. Inhibitors and glycosidase treatments, and pulse-chase labelling experiments, revealed the glycosylation process of HBsAg. The latter was synthesized as a non-glycosylated 26K protein and subjected to N-linked glycosylation to form a 30K protein with high mannose glycans. Three species of dimers composed of 26K and 30K subunits were then formed with disulphide bonds. Both subunits of the dimers were further subjected to O-linked glycosylation and conversion from high mannose glycans to complex glycans followed by sialylation. Three species of dimers composed of 30K and 35K subunits were secreted into the culture supernatant as HBsAg particles. HBsAg was synthesized, glycosylated with both N- and O-linked glycans, sialylated, and then secreted into the culture supernatant within 1 h. These modifications of HBsAg by glycans might stabilize its structure and enhance its immunogenicity as a live HBV vaccine.

Electrophoresis, Polyacrylamide Gel↗

PubMed1992

Diagnosis of typhus infection with Rickettsia tsutsugamushi by polymerase chain reaction.

Two sets of oligonucleotide primers were used to amplify the genomic DNA of Rickettsia tsutsugamushi, the causative agent of scrub typhus (tsutsugamushi disease), by the polymerase chain reaction. Each set of primers amplified 538-bp and 109-bp products, representing part of a gene encoding a possible major 58-kDa immunogenic protein, from whole genomic DNA extracted from R. tsutsugamushi strains Karp, Kato, Gilliam, Kuroki and Kawasaki. No amplification was observed from R. sibirica, R. rickettsii, mouse and human genomic DNA. DNA amplification was observed from crude lysates of peripheral whole blood, tissue homogenates and paraffin-embedded skin biopsy sections obtained from patients with scrub typhus disease. Southern blot analysis demonstrated the specificity of the amplified DNA fragments following hybridisation with a DNA probe generated from R. tsutsugamushi strain Karp. By means of this procedure, a rapid and sensitive diagnosis of scrub typhus disease can be made during the acute stage of this infection.

Acute Disease↗

PubMed1992

Production of multiple growth factors by a newly established human thyroid carcinoma cell line.

A multiple growth factor-producing tumor cell line (NIM-1) was newly established from a patient with thyroid cancer and remarkable neutrophilia. NIM-1 cells also caused severe neutrophilia in nude mice bearing tumors. NIM-1-conditioned medium (NIM-1CM) contained activities that supported not only granulocyte, macrophage and eosinophil colony formation of human bone marrow cells but also the growth of colony-stimulating factor (CSF)-dependent cell lines, NFS60-KX and TF-1. Northern blot hybridization analysis revealed the constitutive expression of granulocyte-CSF (G-CSF), granulocyte/macrophage-CSF (GM-CSF) and interleukin(IL)-6 mRNAs in NIM-1 cells. Enzyme-linked immunosorbent assays (ELISA) using NIM-1CM also confirmed the production of IL-1 alpha and a small amount of IL-1 beta besides G-CSF, GM-CSF and IL-6 in NIM-1 cells. In addition, unexpected production of IL-11 in NIM-1 cells was detected by northern blot hybridization analysis and by bioassay using an IL-11-dependent cell line. Therefore, NIM-1 cell line is shown to produce multiple cytokines including potentially megakaryopoietic growth factors such as GM-CSF, IL-6 and IL-11.

Adenocarcinoma, Papillary↗

PubMed1992

Vertical transmission of HTLV-1 in HTLV-1 carrier rat.

A female F344 rat was injected with 2.4 x 10(6) MT-2 cells intravenously at 3 and 4 weeks old, and was mated with a non-infected male rat at the 17th week after injection, when the dam rat contained HTLV-1 provirus in the peripheral blood mononuclear cells as determined by polymerase chain reaction. HTLV-1 provirus was detected in at least 2 out of 9 offspring. This system should be useful for studies on the routes and prevention of vertical transmission and on elimination of once-transmitted HTLV-1.

Animals↗

PubMed1992

Remission with morphological myelodysplasia in de novo acute myeloid leukaemia: implications for early relapse.

Myelodysplastic features of remission bone marrow were investigated in 46 adults with de novo acute myeloid leukaemia (AML) according to the FAB morphological criteria for myelodysplastic syndromes (MDS). Compared with a group of 18 patients with the common type of acute lymphoblastic leukaemia in remission, micromegakaryocytes (30.4% v. 5.6%, P less than 0.05), multi-separated nuclear megakaryocytes (45.7% v. 0%, P less than 0.01), degranulated neutrophils (39.1% v. 5.6%, P less than 0.05), and neutrophils with hyposegmented nuclei (34.8% v. 0%, P less than 0.01) were significantly more common in the AML patients. In contrast, dyserythropoietic changes had a similar incidence in both groups. When compared with the clinical features at initial diagnosis in AML cases, the dysmegakaryocytic changes in remission marrow were found to be significantly more frequent in patients with monocytic involvement (mainly M4) or trilineage myelodysplasia (T-MDS AML). Disease-free survival was significantly shorter in patients with micromegakaryocytes (P less than 0.05) or neutrophils with hypogsegmented nuclei (P less than 0.05) than in those without these features. Overall survival was also significantly shorter in patients with micromegakaryocytes (P less than 0.05). These findings may help in developing new strategies for the post-remission therapy of AML, and also suggest that myelodysplastic changes in the remission marrow of de novo AML patients may be related to haematopoietic recovery by a preleukaemic clone which eventually leads to early leukaemic relapse. Dysplastic marrow, however, was not necessarily associated with peripheral pancytopenia in the present series, warranting basic research on such putative clonal remissions.

Acute Disease↗

PubMed1992

Myelodysplastic syndrome (MDS)-associated inhibitory activity on haematopoietic progenitor cells: contribution of monocyte-derived lipid containing macrophages (MDLM).

We studied myelodysplastic syndrome-associated inhibitory activity (MDS-IA), which inhibited colony formation in vitro of normal granulocyte-macrophage progenitors (CFU-GM). When adherent marrow cells were incubated with fetal calf serum for 21-24 d, monocyte-derived lipid containing huge macrophages (MDLM) developed. MDLM from MDS marrow (MDS-MDLMs) and their conditioned medium (MDLM-CM) consistently suppressed the growth of normal CFU-GM colony formation. MDS-IA was active on CFU-GM during the S-phase and relatively resistant to heating. Monoclonal antibody against H subunit (acidic) ferritin and polyclonal antibody against placental ferritin neutralized the inhibitory activity of MDS-MDLMs. In addition, cell lysates of MDS-MDLMs reacted to both monoclonal anti-H subunit ferritin and polyclonal anti-placental ferritin in Western blotting analysis, indicating that the inhibitory activity was predominantly acidic isoferritin. On the other hand, MDLMs obtained from normal bone marrow had a CFU-GM enhancing activity. These results suggest that MDS-MDLMs may be responsible for the suppression of granulopoiesis in patients with MDS and that the suppression may be mediated by soluble factors, notably H subunit isoferritin.

Adolescent↗

PubMed1992

Effect of salicylic acid and calcium on mitochondrial functions.

The rapid mitochondrial uptake of calcium followed by slow release in certain pathophysiological states associated with an increase in intracellular calcium, to normalize the cytoplasmic levels of free calcium, provides an important protective mechanism against calcium cellular toxicity. Salicylic acid, an in vivo metabolite of aspirin, inhibits the uptake and enhances the release of calcium by mitochondria, thereby increasing the levels of cytoplasmic free calcium. The Ca2+ induced mitochondrial swelling is enhanced in the presence of salicylic acid and in which turn leads to loss of biosynthesis of ATP. These results suggest that salicylic acid may promote cellular damage in pathophysiological states associated with increase in intracellular free calcium.

Adenosine Triphosphate↗

PubMed1992

Patients with homocystinuria: high metal concentrations in hair, blood and urine.

Patients with homocystinuria excrete a large amount of metal in their urine. Homocysteine similar to penicillamine, administration to methylmercury treated rats resulted in a large amount of urinary methylmercury excretion. These results suggested that the total metal amounts in the whole body of patients with homocystinuria might be decreased. However, actually metal concentrations in hair and plasma of these patients were higher than those of normal controls. High plasma and hair metal levels are not accounted for in patients with homocystinuria. The physiological metal excretory mechanism in which small amounts of metals bind to the small, plasma molecular substances filter through the kidney and emerge in the urine is necessary for reconfirmation. Strongly perturbed metal metabolism exists in the patients with homocystinuria.

Adult↗

PubMed1992

Endothelial cell morphometry of atherosclerotic lesions and flow profiles at aortic bifurcations in cholesterol fed rabbits.

Observations on shapes of endothelial cells both in sudanophilic and nonsudanophilic regions at bifurcations of the brachiocephalic (BC) and left subclavian (SA) arteries in hyperlipidemic rabbits were performed under a SEM. The stagnation point of flow and leading edges of flow dividers were nonsudanophilic and covered by round and long fusiform endothelial cells, respectively. The hips of flow dividers of both branchings, proven to be relatively low shear stress regions, by movement of microspheres in steady flow, were sudanophilic and covered by ellipsoidal cells. Similar studies were carried out in normolipidemic rabbits. It might be concluded that lipid deposition in hyperlipidemic rabbits occurs in relatively low shear stress regions, where endothelial cells are functionally activated, rather than in laminar high shear stress regions at the flow divider.

Animals↗

PubMed1992

Epidemiology of Tsutsugamushi disease in relation to the serotypes of Rickettsia tsutsugamushi isolated from patients, field mice, and unfed chiggers on the eastern slope of Mount Fuji, Shizuoka Prefecture, Japan.

A total of 59 strains of Rickettsia tsutsugamushi were isolated from patients (24 isolates), Apodemus speciosus mice (30 isolates), and unfed larvae of Leptotrombidium scutellare (2 isolates) and Leptotrombidium pallidum (3 isolates) in the Gotenba-Oyama District, Shizuoka Prefecture, Japan. All these isolates were classified into the three serotypes Karp, Kawasaki, and Kuroki based on reactivity with strain-specific monoclonal antibodies. Kawasaki- and Karp-type rickettsiae were isolated from L. scutellare and L. pallidum, respectively, and the geographic distribution of patients and rodents infected with these two types of rickettsiae coincided with the areas densely populated by the respective chiggers. From these results, we conclude that Kawasaki-type rickettsiae are transmitted by L. scutellare and Karp-type ones are transmitted by L. pallidum. Kawasaki-type rickettsial infections were prevalent in early autumn, and Karp-type infections showed a peak of occurrence in the late autumn, reflecting the seasonal fluctuations of L. scutellare and L. pallidum. Isolates of Kuroki-type rickettsiae were obtained only from four patients in October and November, and the relationship between this type of rickettsia and its vector species could not be fully defined.

Animals↗

PubMed1992

Microinjection of smg/rap1/Krev-1 p21 into Swiss 3T3 cells induces DNA synthesis and morphological changes.

Microinjection of either Ki-rasVal-12 p21 or the GDP-bound form of Ki-ras p21 plus smg GDP dissociation stimulator (GDS), a stimulatory GDP/GTP exchange protein for Ki-ras p21, smg/rap1/Krev-1 p21, and rho p21, into quiescent Swiss 3T3 cells induced DNA synthesis irrespective of the presence or absence of insulin. The guanosine 5'-(3-O-thio)triphosphate (GTP gamma S)-bound form of smg p21B or the GDP-bound form of smg p21B plus smg GDS also induced DNA synthesis but only in the presence of insulin. Either the GDP-bound form of Ki-ras p21 or the same form of smg p21B alone was inactive, but smg GDS alone was slightly active only in the presence of insulin. The morphology of the cells was analyzed by scanning electron, phase-contrast, and confocal laser scanning microscopies. Ki-rasVal-12 p21 induced membrane ruffling irrespective of the presence or absence of insulin. The GTP gamma S-bound form of smg p21B showed the same effect only in the presence of insulin. Either the GDP-bound form of Ki-ras p21, the same form of smg p21B, or smg GDS alone was inactive. Upon microinjection of Ki-rasVal-12 p21, stress fibers markedly decreased and the cells became round and piled up. In contrast, upon microinjection of the GTP gamma S-bound form of smg p21B, stress fibers did not markedly decrease and the cells neither became round nor piled up. These results indicate that both ras p21 and smg p21 are mitogenic in Swiss 3T3 cells but that their actions are slightly different.

3T3 Cells↗

PubMed1992

Purification, properties, and partial amino acid sequence of chitinase from a marine Alteromonas sp. strain O-7.

Chitinase (EC 3.2.1.14) was isolated from the culture supernatant of a marine bacterium, Alteromonas sp. strain O-7. The enzyme (Chi-A) was purified by anion-exchange chromatography (DEAE-Toyopearl 650 M) and gel filtration (Sephadex G-100). The purified enzyme showed a single band on sodium dodecyl sulfate polyacrylamide gel electrophoresis. The molecular size and pI of Chi-A were 70 kDa and 3.9, respectively. The optimum pH and temperature of Chi-A were 8.0 and 50 degrees C, respectively. Chi-A was stable in the range of pH 5-10 up to 40 degrees C. Among the main cations, such as Na+, K+, Mg2+, and Ca2+, contained in seawater, Mg2+ stimulated Chi-A activity. N-Bromosuccinimide and 2-hydroxy-5-nitrobenzyl bromide inhibited Chi-A activity. The amino-terminal 27 amino acid residues of Chi-A were sequenced. This enzyme showed sequence homology with chitinases from terrestrial bacteria such as Serratia marcescens QMB1466 and Bacillus circulans WL-12.

Amino Acid Sequence↗

PubMed1992

Effects of oral adsorbent in the rat model of chronic renal failure.

The effects of oral adsorbent, AST-120 (Kureha Chemical Ind. Co., Tokyo), were studied in the rat model of subtotal nephrectomy. In 34 female Sprague-Dawley rats, three quarters of the renal mass were removed from the left kidney by ligation of 3 branches of the left renal artery. One week later, the right kidney was removed. Two days after right nephrectomy, control rats were fed standard rat chow ad libitum, while AST-120-treated rats were fed standard rat chow containing AST-120 ad libitum. The animals were observed for 9 weeks. Of the control rats, some became severely ill and appeared to be almost dying before 9 weeks, while paired AST-120-treated rats appeared well. Body weight was maintained better in AST-120-treated rats than in control rats. At completion of the study, levels of BUN and serum creatinine were lower and glomerular filtration rate and renal plasma flow rate were higher in AST-120-treated than in control rats (p < 0.05), although there was no statistically significant difference in proteinuria. Serum uremic peak 2a measured by high-performance liquid chromatography, which is considered to correspond to uremic toxins, was statistically lower in AST-120-treated rats (p < 0.05). Finally, a marked reduction in the degree of glomerular sclerosis was noted in AST-120-treated versus control rats (p < 0.05). The results indicate that AST-120 is effective in the treatment of chronic renal failure in terms of reducing uremic symptoms as well as preserving renal function and glomerular architecture. The data also indicate that a reduction in uremic toxins could delay the progressive damage of renal function and glomerular architecture in chronic renal failure.

Adsorption↗

PubMed1992

Hypothermia reduces 72-kDa heat-shock protein induction in rat brain after transient forebrain ischemia.

BACKGROUND AND PURPOSE: We examined the influence of concurrent moderate hypothermia (30 degrees C) and transient forebrain ischemia on the induction of 72-kDa heat-shock protein and neuronal damage in male Wistar rats. SUMMARY OF REPORT: Experimental groups included: normothermic with 8 minutes of transient forebrain ischemia (group 1, n = 7), hypothermic without ischemia (group 2, n = 9), and hypothermic (30 degrees C) with 8 minutes of transient forebrain ischemia (group 3, n = 5). Intense 72-kDa heat-shock protein immunoreactivity was demonstrated in rat forebrain 48 hours after induction of normothermic forebrain ischemia (group 1); it was not detected in the brain of animals subjected to hypothermia without ischemia (group 2), and hypothermia during ischemia (group 3) significantly inhibited its expression compared with that in normothermic ischemia animals (group 1). CONCLUSIONS: These observations suggest that 72-kDa heat-shock protein induction is not the mechanism by which moderate hypothermia protects against ischemic cell damage.

Animals↗

PubMed1992

Distribution of the 72-kd heat-shock protein as a function of transient focal cerebral ischemia in rats.

BACKGROUND AND PURPOSE: The significance and physiological implications of the expression of the 72-kd heat-shock protein in ischemic tissue are unknown. To enhance our understanding of the relation between ischemic cell damage and 72-kd heat-shock protein expression, we evaluated the cellular expression and the anatomic distribution of 72-kd heat-shock protein in conjunction with the morphological analysis of rat brain, as a function of the duration of a single arterial occlusion. METHODS: Adult Wistar rats were subjected to graded transient middle cerebral artery occlusion (for a duration of 10, 20, 30, 60, 90, and 120 minutes and sham; n = 4 per group). Forty-eight hours after reopening the artery, brain tissue sections were analyzed to determine the extent of neuronal damage (hematoxylin and eosin staining), the extent of astrocytic reactivity (immunohistochemistry, using anti-glial fibrillary acidic protein), and the distribution of 72-kd heat-shock protein (immunohistochemistry, using a monoclonal antibody to 72-kd heat-shock protein). RESULTS: We found that 72-kd heat-shock protein was sequentially expressed in morphologically intact neurons, microglia, and endothelial cells with increasing duration of ischemia; 72-kd heat-shock protein immunoreactivity was not detected in astrocytes. The duration of ischemia required to evoke a 72-kd heat-shock protein response in neurons was dependent on the anatomic site and followed a pattern of increasing neuronal sensitivity to ischemic cell damage with duration of ischemia: 72-kd heat-shock protein and neuronal damage were sequentially detected in the caudate putamen, globus pallidus, cerebral cortex, amygdala, and hippocampus with increasing duration of ischemia. With ischemia of long duration (greater than or equal to 90 minutes), neurons expressing 72-kd heat-shock protein were localized to a zone peripheral to the severely damaged ischemic core. CONCLUSIONS: These studies suggest that 1) the expression of 72-kd heat-shock protein in neurons precedes the development of ischemic cellular alterations detectable by conventional hematoxylin and eosin light microscopy methods; 2) there is a hierarchy of cell types and anatomic sites that express 72-kd heat-shock protein, and this hierarchy reflects cellular and anatomic vulnerability to ischemic cell damage; and 3) 72-kd heat-shock protein induction in neurons bordering a necrotic ischemic core may be the morphological equivalent of the ischemic penumbra.

Animals↗

PubMed1992

An interpretation of cell separation mechanism on polyamine graft copolymers.

Interaction between polyamide microcapsules having different balances of negative and positive charges on their surface, that is, different isoelectric points and copolymers with different numbers of polyamine macromer of a definite chain length grafted on poly(2-hydroxyethyl methacrylate) backbone was studied by measuring the amount adhered of the microcapsules onto the surface of copolymer-coated glass beads at different pH values. Maximum microcapsule adhesion was observed for a proper combination of microcapsule and copolymer to suggest that separation of a specified cell population from others on the surface of copolymer-coated glass beads can be explained in terms of preferential adhesion through electrostatic interaction of the specified cells with the copolymer.

Cell Separation↗

PubMed1992

Myocardial Na+ during ischemia and accumulation of Ca2+ after reperfusion: a study with monensin and dichlorobenzamil.

The intracellular cation contents were determined in isolated perfused rat heart using cobaltic EDTA as a marker of the extracellular space. In hearts in which Na+ accumulation was induced with monensin, a Na+ ionophore, during 20 min-ischemia which otherwise did not result in accumulation of Na+, the levels of Na+ and Ca2+ were significantly higher after reperfusion with a significant decrease in K+. While the recovery of the cardiac mechanical function (CMF) was complete after reperfusion in control hearts, the recovery was incomplete in monensin-hearts. Dichlorobenzamil (DCB), the most specific inhibitor of Na(+)-Ca2+ exchanger, infused for 10 min before induction of ischemia in a dose of 10(-5) M, which produced a definite suppression of CMF (over 80%), inhibited the accumulation of Ca2+ and Na+ and the loss of K+ and ATP after 40 min-ischemia and reperfusion. The same dose of DCB given for 3 min before induction of ischemia and after reperfusion, which produced a less than 20% inhibition of CMF, failed to prevent the Ca2+ accumulation after 40 min-ischemia and reperfusion. These findings are at variance with the idea that the accumulation of Na+ during ischemia and the consequent augmented operation of Na(+)-Ca2+ exchange is responsible for accumulation of Ca2+ after reperfusion.

Adenine Nucleotides↗

PubMed1992

An endoscopic study of antibiotic-associated hemorrhagic colitis.

Colonoscopy was performed on acute stage within 72 hours from onset in 48 patients with antibiotic-associated hemorrhagic colitis (AAHC). From our observations we have developed a new endoscopic classification of AAHC and investigated the incidence of each finding in further detail. We have classified in principle the endoscopic findings of the 48 subjects into two groups: major and minor ones respectively. Category of major findings were: 1) diffuse mucosal hemorrhage (100%); 2) spotty mucosal hemorrhage (100%), and 3) linear mucosal hemorrhage (22.9%), while minor findings were: 1) irregular ulcers in 10.4%; 2) aphthoid ulcers in 6.3%, and 3) linear erosions or ulcers in 4%. Minor findings were ulcers or erosions present over the hemorrhagic mucosa associated with the moderate degree of inflammation. A histopathologic study of colon biopsy specimens from 24 patients with AAHC showed hemorrhage and inflammatory cell infiltration in the lamina propria mucosae varying from mild to moderate in extent. It was concluded that AAHC was a colonic mucosal hemorrhagic disease caused by the destruction of mucosal vessels from unknown causes and in this disease mild to moderate inflammation was partially followed by ulceration over the edematous and hemorrhagic mucosa of the colon.

Adolescent↗