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Biomedical subjects

Y Toyoda

Publications and source records attributed to Y Toyoda.

At least 19 recordsLinked to original sources
PubMed2000

Localization of glucokinase-like immunoreactivity in the rat lower brain stem: for possible location of brain glucose-sensing mechanisms.

Pancreatic glucokinase (GK) is considered an important element of the glucose-sensing unit in pancreatic beta-cells. It is possible that the brain uses similar glucose-sensing units, and we employed GK immunohistochemistry and confocal microscopy to examine the anatomical distribution of GK-like immunoreactivities in the rat brain. We found strong GK-like immunoreactivities in the ependymocytes, endothelial cells, and many serotonergic neurons. In the ependymocytes, the GK-like immunoreactivity was located in the cytoplasmic area, but not in the nucleus. The GK-positive ependymocytes were found to have glucose transporter-2 (GLUT2)-like immunoreactivities on the cilia. In addition, the ependymocytes had GLUT1-like immunoreactivity on the cilia and GLUT4-like immunoreactivity densely in the cytoplasmic area and slightly in the plasma membrane. In serotonergic neurons, GK-like immunoreactivity was found in the cytoplasm and their processes. The present results raise the possibility that these GK-like immunopositive cells comprise a part of a vast glucose-sensing mechanism in the brain.

Animals↗
PubMed1999

Antibody reactivity in mice and cats to feline enteroepithelial stages of Toxoplasma gondii.

The reactivity of antibodies in mice and cats to feline enteroepithelial stages of Toxoplasma gondii was examined by means of an indirect immunofluorescent antibody test. Mice immunized with feline enteroepithelial stage (FES) parasites produced antibodies not only against FES, but also against tachyzoites, sporozoites/oocysts, tissue cysts and one part of the infected feline enterocytes. After absorption with tachyzoites, the titer of antibodies reactive to enterocytes was significantly reduced. In contrast, the titer of antibodies reactive to FES remained unchanged. The antibodies from cats immunized with FES, reacted specifically to FES, but not to tachyzoites, tissue cysts or enterocytes. These results suggest that FES parasites may have stage-specific antigen(s).

Animals↗
PubMed1999

Mammalian transgenesis by intracytoplasmic sperm injection.

Coinjection of unfertilized mouse oocytes with sperm heads and exogenous DNA encoding either a green fluorescent protein (GFP) or beta-galactosidase reporter produced 64 to 94 percent transgene-expressing embryos, reflecting DNA-sperm head association before coinjection. Nonselective transfer to surrogate mothers of embryos in the GFP series generated about 20 percent offspring expressing the integrated transgene. These data indicate that exogenous DNA can reproducibly be delivered into an oocyte by microinjected spermatozoa and suggest an adaptable method of transgenesis.

Animals↗
PubMed1999

Infectivity of feline enteroepithelial stages of Toxoplasma gondii isolated by Percoll-density gradient centrifugation.

The infectivity of the feline enteroepithelial stages of Toxoplasma gondii isolated by Percoll-density gradient centrifugation was examined by the trypan blue dye exclusion method by assaying their penetration into feline fibroblast cells in vitro and by inoculation of the intestinal mucosa of cats. A large population of the parasites showed trypan blue dye exclusion activity. When feline fibroblast cells were inoculated with feline enteroepithelial stage parasites, no intracellular parasites were found 18 h post-inoculation. Kittens inoculated intraduodenally with 2 x 10(6) feline enteroepithelial stage parasites shed oocysts between 2 and 8 days post-inoculation. These results indicate that the isolated feline enteroepithelial stage parasites display infectivity towards enterocytes of cats and are capable of gametogenesis.

Animals↗
PubMed1999

Identification of carbohydrates on Eimeria stiedai sporozoites and their role in the invasion of cultured cells in vitro.

The carbohydrates present on Eimeria stiedai sporozoites and their functional role in the process of invasion of host cells were examined. Lectin-binding sites on the surface of sporozoites were detected by means of peroxidase-conjugated lectins. Sporozoites showed specific binding with UEA-I and PNA lectins, which bind L-fucose and D-galactose, respectively. Exposure of sporozoites to 100 microg/ml UEA-I significantly reduced their ability to invade primary rabbit liver biliary epithelial cells, but similar treatment with PNA had no such effect. Pre-incubation of these cells in Dulbecco's minimum essential medium containing 10% fetal bovine serum and 1% L-fucose suppressed the invasion activity of the sporozoites, but pre-incubation of the sporozoites in the same medium without L-fucose had no effect on cell penetration. D-galactose added to the medium had no effect on the invasion activity of sporozoites. These results indicate that L-fucose residues on E. stiedai sporozoites and L-fucose-binding sites on host cells both are associated with the recognition and/or invasion process.

Animals↗
PubMed1999

Conversion of right atrioventricular to total cavopulmonary anastomosis in the management of post-Fontan arrhythmia: report of a case.

Both the original and modified Fontan procedures are associated with several late complications such as atrial arrhythmias, thromboembolism, and right pulmonary vein compression caused by a markedly enlarged right atrium. We describe herein the case of a patient who underwent conversion of right atrioventricular to total cavopulmonary anastomosis to control atrial arrhythmia that developed 12 years after a modified Fontan operation. The procedure proved successful in alleviating his symptoms immediately. He is now doing well with no recurrence of atrial arrhythmia 1 year after the operation.

Arrhythmias, Cardiac↗
PubMed1999

Glucokinase is concentrated in insulin-secretory granules of pancreatic B-cells.

We immunohistochemically examined the distribution of glucokinase (GK) in the B-cells of pancreatic islets of normal rats. GK was stained punctately in the cytoplasm of B-cells when examined under the light microscope. By use of a double-immunostaining technique, most of the GK immunoreactivity was observed to be colocalized with insulin immunoreactivity. Electron microscopic examination by the immunogold method revealed that GK immunoreactivity was predominantly located within insulin-secretory granules of pancreatic B-cells. Exploration of the intracellular distribution of GK in hepatocytes suggested that the shuttling of the enzyme between the nucleus and the cytoplasm is essential for the regulation of GK activity (Toyoda et al. 1994, 1995, 1996a,b, 1997a). As an approach to the elucidation of the mechanism of control of GK activity, we immunohistochemically investigated the intracellular distribution of the enzyme in pancreatic B-cells under both light microscopy and electron microscopy in this study. A preliminary report of the present study has been published.

Animals↗
PubMed1999

Tubular structures associated with Babesia caballi in equine erythrocytes in vitro.

In-vitro-propagated Babesia caballi parasites were examined by scanning and transmission electron microscopy. Many small pores were observed over the entire surface of infected erythrocytes on scanning electron microscopy, and on transmission electron microscopy these small pores were found to be openings of tubular structures. By the examination of a number of infected cells the tubular structures were found to be connected with the parasite, and this observation might indicate that the tubular structures arose the edge of the parasite and terminated at an Invagination on the surface of the erythrocyte. These findings suggest that intraerythrocytic stages of B. caballi come into direct contact with culture medium.

Animals↗
PubMed1999

Increased susceptibility to Toxoplasma gondii infection in SAG-1 transgenic mice.

SAG-1, one of the major surface proteins of Toxoplasma gondii, has been reported to play an important role in immune and pathogenic mechanisms of the parasites but its exact function is still unclear. We investigated the time courses of T. gondii infection in B6C3F1 transgenic mice carrying the SAG-1 gene. SAG-1 transgenic mice were infected intraperitoneally with a high virulent RH strain or a low virulent Beverley strain of T. gondii. When infected with RH strain tachyzoites, no significant differences in time courses of survivals between SAG-1 transgenic and wild-type mice were observed. Both groups succumbed to an acute infection within 8 days after infection. However, a lower survival rate (20%) was observed in SAG-1 transgenic mice than in wild-type (80%), when infected with Beverley strain cysts. This result indicates that SAG-1 transgenic mice are more susceptible to T. gondii infection as compared with their wild-type counterpart. ELISA using recombinant SAG-1 protein indicates that SAG-1 transgenic mice do not produce antibodies to the SAG-1 molecule. These findings may provide a critical tool for analysing the molecular mechanisms of pathogenesis and host immune responses during toxoplasmosis.

Animals↗
PubMed1999

Inhibitory effect of monoclonal antibodies on the growth of Babesia caballi.

Monoclonal antibodies (mAbs) were produced against Babesia caballi (USDA strain) to define a species-specific antigen for use in diagnosis and vaccine development. Eight positive clones of B. caballi mAbs determined by indirect immunofluorescent antibody test were selected for purification and further characterisation. Confocal laser microscopy showed that the antigens recognised by the mAbs were located on the surface/cytoplasm, central part, and/or anterior end of B. caballi parasites, with five different reactive patterns. These mAbs seemed to be species-specific, since they did not cross-react with Babesia equi-infected erythrocytes or uninfected erythrocytes. In Western blotting analysis, 18, 20, 34, 36, 48, and 155 kDa proteins of B. caballi merozoites were recognised by six different mAbs. When added to in vitro cultures, four of the mAbs significantly inhibited the in vitro growth of B. caballi parasites. These results provide a rationale for evaluating antigens for the development of diagnostic methods or vaccines.

Animals↗
PubMed1999

Changes in immune function following surgery for esophageal carcinoma.

Changes in immune function due to surgical injury have been well-documented. Immunosuppression is one of the causes of infectious complications leading to organ dysfunction in critical illness. It is not known what kind of surgery in the daily clinical practice causes immunosuppression. Stress response and immune function following surgery for esophageal carcinoma, assuming a highly-stressed operation, were studied and then compared with the stress response and immune function following gastric surgery, a moderately-stressed procedure. Forty patients who underwent esophagectomy and 39 patients receiving gastric operation were studied. The concentrations of serum interleukin-6 (IL-6) were measured preoperatively, at 1, 2, and 6 h, and at 1, 3, and 10 d after operation. Total protein, serum albumin, rapid turnover protein, serum CRP, and cortisol were measured before operation and at 1, 3, 7, and 21 d after operation. ConA- and PHA-stimulated lymphocyte proliferation, IgA, IgG, and IgM were also measured preoperatively, and on 7 and 21 d following surgery. The patients were fed exclusively by total parenteral nutrition (TPN). A striking rise of IL-6 was observed, with a peak in both groups at 1 to 6 h following operation. The peak values were 419+/-30 pg/mL, which was approximately twice as high in the esophagectomy patients as in the gastrectomy patients (195+/-40 pg/mL). CRP and cortisol also increased after operation, and these increases were also significantly greater in the esophagectomy patients. ConA- and PHA-stimulated lymphocyte proliferation decreased significantly 7 d after esophagectomy (P<0.05), but was unchanged in the patients receiving gastrectomy. Suppression of cellular immunity correlated significantly with serum cortisol, and was preceded by a rise in serum IL-6. The IgA, IgG, and IgM levels, however, remained unchanged from their preoperative values throughout the study in both groups. Nutritional status in terms of serum protein, albumin, and rapid turnover protein, decreased postoperatively, but there was no difference between the two groups. It is, therefore, concluded that cell-mediated immunosuppression, preceded by a hyperinflammatory response, is an observable reaction in patients following esophageal surgery, but not in patients undergoing gastric surgery.

Aged↗
PubMed1999

Inactivation of p34cdc2 kinase by the accumulation of its phosphorylated forms in porcine oocytes matured and aged in vitro.

Culturing of matured porcine oocytes in vitro results in the enhancement of their cytoplasmic ability for oocyte activation (so-called ageing), although they are arrested at metaphase II. The enhanced ability for oocyte activation is related to decreased activity of the maturation promoting factor (MPF). In the present study we clarified the molecular mechanism of MPF inactivation during ageing, especially the changes in the phosphorylation status of p34cdc2, a catalytic subunit of MPF, compared with that in fertilised oocytes. The MPF activity decreased gradually when maturation culture was prolonged from 36 to 72 h, confirming the decreasing MPF activity in aged oocytes. The activity of 48 h matured oocytes also decreased after in vitro fertilisation. Immunoblotting of p34cdc2 with anti-PSTAIRE antibody revealed that the culturing of matured oocytes induces a gradual increase in pre-MPF, which is a p34cdc2 and cyclin B complex inactivated by phosphorylation at the inhibitory phosphorylation site of p34cdc2. In contrast, pre-MPF decreased after fertilisation, indicating the degradation of cyclin B. These results suggest that the molecular mechanisms of inactivation of MPF are different between oocyte activation and ageing, and that the mechanism during ageing might be based on the inhibitory phosphorylation of p34cdc2, whereas that of oocyte activation is based on the degradation of cyclin B.

Amino Acid Sequence↗
PubMed1999

Effects of soybean oil emulsion and eicosapentaenoic acid on stress response and immune function after a severely stressful operation.

OBJECTIVE: To investigate the effects of soybean oil emulsion and oral or enteral administration of eicosapentaenoic acid (EPA) on stress response, cytokine production, protein metabolism, and immune function after surgery for esophageal cancer. SUMMARY BACKGROUND DATA: It has been reported that safflower oil, rich in n-6 polyunsaturated fatty acid (n-6 PUFA), affects the survival rate of septic animals and decreases the immune function. It has also been reported that the administration of fish oil, in contrast, reduces these stress responses and stress-induced immunosuppression. In humans, the effects of soybean oil emulsion and the administration of EPA on stress response and immune function after surgery have not been established. METHODS: Patients who underwent esophagectomy with thoracotomy were divided into three groups. Seven patients were fed by total parenteral nutrition (TPN) with soybean oil emulsion, which accounted for 20% of total calories. Seven patients were given oral or enteral administration of 1.8 g/day EPA, in addition to TPN with soybean oil emulsion. Nine patients served as the control group; these patients received fat-free TPN. Serum interleukin-6 (IL-6), C-reactive protein, concanavalin A (con A)- or phytohemagglutinin (PHA)-stimulated lymphocyte proliferation, natural killer cell activity, and stress hormones were measured. RESULTS: The postoperative level of serum IL-6 was significantly higher in the group receiving soybean oil emulsion than in the fat-free group. Oral or enteral supplementation of EPA with soybean oil emulsion significantly reduced the level of serum IL-6 compared with the patients receiving soybean oil emulsion. Con A- or PHA-stimulated lymphocyte proliferation decreased significantly on postoperative day 7 in all groups of patients. The supplementation of EPA with soybean oil emulsion significantly improved the lymphocyte proliferation and natural killer cell activity on postoperative day 21 compared with the group receiving soybean oil emulsion. CONCLUSIONS: Soybean oil emulsion amplifies, and the supplementation of EPA reduces, the stress response and stress-induced immunosuppression.

Eicosapentaenoic Acid↗
PubMed1999

Coronary artery spasm induced by trigeminal nerve stimulation and vagal reflex during intracranial operation.

This report describes a case of ventricular fibrillation resulting from coronary vasospasm during intracranial operation under general anesthesia. An autonomic response associated with the intracranial procedure caused a coronary spasm, which was worsened by alpha-agonists. Nitroglycerin effectively resolved the coronary spasm and co-complications persisted.

Adrenergic alpha-Agonists↗
PubMed1999

Fusobacterium necrophorum haemolysin stimulates motility of ileal longitudinal smooth muscle of the guinea-pig.

Fusobacterium necrophorum haemolysin (0.5-3.1 mg protein/mL) dose-dependently induced contractions of the isolated ileal longitudinal smooth muscle of the guinea-pig. The haemolysin (3.1 mg protein/mL) -induced maximum contraction of 75% of the response to 60 mM K+ declined within 17 min and the muscles then demonstrated rhythmic contractions. Tetrodotoxin (3.1 x 10(-6) M) had no effect on the contraction due to the haemolysin. After incubation in Ca(2+)-free medium, the ileal response to the haemolysin was lost. Verapamil, a Ca2+ channel blocker, dose-dependently inhibited the contraction to the haemolysin. The rabbit anti-serum against F. necrophorum haemolysin inhibited the haemolysin-induced contraction of ileal muscle. The bacterial haemagglutinin and the lipopolysaccharide had no effect on the response of ileal muscle. These findings suggest that the haemolysin-induced direct stimulation of ileal motility dependant on Ca2+ influx will increase the probability of contact of F. necrophorum and ileal mucosa and could increase the chances of colonization for F. necrophorum.

Animals↗