Biomedical subjects

S Goto

Publications and source records attributed to S Goto.

At least 343 records · Page 19Linked to original sources

PubMed1997

Organizing and computing metabolic pathway data in terms of binary relations.

A new database system named KEGG is being organised to computerize functional aspects of genes and genomes in terms of the binary relations of interacting molecules or genes. We are currently working on the metabolic pathway database that is composed of three interconnected sections: genes, molecules, and pathways, which are also linked to a number of existing databases through our DBGET retrieval system. Here we present the basic concept of binary relations and hierarchical classifications to represent the metabolic pathway data. The database operations are then defined as an extension of the relational operations, and the path computation problem is considered as a deduction from binary relations. An example of using KEGG for the functional prediction of genomic sequences is presented.

Animals↗

PubMed1997

Identification of genes specifically expressed in chronic and progressive glomerulosclerosis.

To identify genes expressed predominantly in the kidney with chronic and progressive glomerulosclerosis but not in acute and transient form of glomerulonephritis, we induced progressive glomerulosclerosis in rats by applying unilateral nephrectomy prior to injection of monoclonal anti-Thy1.1 antibody (OX-7), which cause acute and transient glomerulonephritis with single injection. In rats with nephrectomy and OX-7 injection (Nx group), proteinuria increased with time and mesangial expansion accompanied with interstitial fibrosis was recognized, whereas transient proteinuria and mesangiolysis followed by mesangial hypercellularity were seen in rats with sham operation and OX-7 injection (Sham group). Four weeks after the induction of glomerulonephritis, mRNAs were isolated from kidney cortex of both groups and used for cDNA synthesis. By subtraction hybridization of cDNAs from Nx with excess amount of those from Sham, we isolated and sequenced several genes expressed specifically in the Nx group. These included genes, which contain identical sequences with serine protease inhibitors, cytokine receptors, osteopontin as well as genes with unknown function. These genes may play important roles in the process which promotes acute glomerular damage advance to chronic and progressive glomerulosclerosis.

Animals↗

PubMed1997

The natural course of nonreducing disc displacement of the TMJ: relationship of clinical findings at initial visit to outcome after 12 months without treatment.

The natural course of untreated nonreducing disc displacement of the temporomandibular joint was evaluated in 52 patients (total of 57 affected temporomandibular joints). The association between the clinical findings at the initial visit and the outcome at 12 months for the age, range of motion for maximum mouth opening, intercuspal-occlusal relationship, morphology of the mandibular fossa and the articular eminence, and the locking duration was evaluated. Good resolution was seen in 59.6% of the patients. The patients with good resolution were significantly younger than those with poor resolution (P < .05, two-tailed t test); however, there were no differences in any other factors between the patients with good resolution and those with poor resolution. Natural resolution of clinical signs and symptoms was suggested for the majority of patients with nonreducing disc displacement of the TMJ, and a younger age at the initial visit appears to be a positive factor in the prognosis.

Adolescent↗

PubMed1996

Involvement of N-methyl-D-aspartate receptor in the delayed transneuronal regression of substantia nigra neurons in rats.

The substantia nigra pars reticulata (SNr) receives both inhibitory GABAergic and excitatory glutamatergic afferents from diverse origins. Ischemic injury to the striatum and/or the globus pallidus causes delayed transneuronal death of the SNr neurons, in the course of which neuronal disinhibition induced by loss of GABAergic inputs is supposed to trigger a lethal hypermetabolic process. In the in vivo experiment presented herein, we clarified the role of glutamatergic action via the N-methyl-D-aspartate receptor in this cell death process. Continuous intraventricular infusion (0.5 microliter/h) of the N-methyl-D-aspartate receptor antagonist MK-801 (1000 micrograms/ml), or of saline (control group) was initiated 24 h after 2 h of transient middle cerebral artery (MCA) occlusion in rats, by which massive ischemic injury was produced in the striatopallidal regions. The measured rectal temperature was not significantly altered in the MK-801-infused and in the control rats throughout the time period examined. The rats were killed at 15 days after MCA occlusion. The volume of the focal ischemic infarction of the MK-801-infused group did not significantly differ from that of controls. Also, MK-801-infusion did not significantly ameliorate the nigral atrophy subsequent to MCA occlusion. In association with a marked depletion of GABAergic afferent fibers, neuronal cell number in the ipsilateral SNr was significantly decreased in the control group. In contrast, the neuronal cell loss in the nucleus was completely prevented in the MK-801-infusion group. The data suggested that withdrawal of GABAergic inputs may cause a severe imbalance between excitation and inhibition of the SNr neurons and may eventually result in neurotoxicity mediated by the N-methyl-D-aspartate receptor. Suppression of glutamatergic excitatory effects by suitable drugs may be a reasonable therapy for the transneuronal death of the SNr neurons.

Animals↗

PubMed1996

Synergistic effect of epinephrine and shearing on platelet activation.

Platelet activation mediated through the interaction between von Willebrand factor (vWF) and platelet glycoprotein (GP) Ib is known to occur under high shear rate. We have demonstrated that low concentration of epinephrine could reduce the threshold level of shear rate necessary to cause platelet activation with purified system devoid of the effect of plasma proteins other than vWF. Both the extent of platelet aggregation and [Ca2+]i were continuously measured with optically modified cone-and-plate viscometer. No aggregation with no change in [Ca2+]i occurred under shear rate less than 7,200 s-1 in the absence of exogeneously added epinephrine. Epinephrine enhanced platelet aggregation under moderate level of shear rate (7,200 s-1) in a dose dependent manner. Significant aggregation with rise in [Ca2+]i was demonstrated even under the low shear rate of 1,200 s-1 when exogeneously added low concentration of epinephrine (0.05 microM) which did not cause platelet activation by itself was present. Aggregation and rise in [Ca2+]i under low shear in the presence of epinephrine was abolished by monoclonal antibodies against A1 domain of vWF or GP Ib, like aggregation and the rise in [Ca2+]i occurred under high shear rate (10,800 s-1), alpha 2-receptor blockade yohimbine completely antagonized the enhancing effects of epinephrine. Our findings suggested that epinephrine and shearing synergistically activated platelets through vWF interaction to GP Ib, which might suggest the role of sympathetic stimulation for the onset of acute arterial thrombosis.

Blood Viscosity↗

PubMed1996

Autocrine mechanism of epidermal growth factor in choriocarcinoma cell proliferation.

We examined four choriocarcinoma cell lines, NaUCC-1, NaUCC-3, NaUCC-4 and BeWo, for the presence of epidermal growth factor (EGF) by enzyme immunoassay and reverse transcription and polymerase chain reaction, and for EGF receptor (EGFR) by 125I-EGF binding assay. Specific EGF binding and EGF proteins were detected in these four choriocarcinoma cell lines. On the cell lines examined, NaUCC-4 had the greatest EGF binding capacity (18 x 10(5) sites/cell) and the highest amount of immunoreactive EGF (142 pg/ml). These results prompted us to assess the significance of EGF/EGFR autocrine mechanism in NaUCC-4 cells. Low doses of exogenous EGF stimulated 3H-thymidine incorporation, and monoclonal antibodies against EGF or EGFR dose-dependently inhibited 3H-thymidine incorporation. On the other hand, these antibodies did not significantly affect hCG production. These results suggested that EGF might function in an autocrine manner to stimulate proliferation rather than differentiation of NaUCC-4 choriocarcinoma cells.

Adult↗

PubMed1996

Effects of hypoxia on the ventral root motor-evoked potential in the in vitro spinal cord preparation.

STUDY DESIGN: This study investigated the effects of hypoxia and glucose on motor functions of spinal cord, monitoring ventral root motor-evoked potential in the in vitro cervical cord preparations. OBJECTIVE: To study ischemia-induced changes in ventral root motor-evoked potential of spinal cord. SUMMARY OF BACKGROUND DATA: Previous studies demonstrated ischemic changes caused by local circulatory impairment might be a major pathophysiologic basis of neuron damage in cord compression. METHODS: Ventral root motor-evoked potential elicited by stimulation of ventrolateral funiculus was recorded from the ventral root in the isolated spinal cord preparations obtained from a newborn rat. The preparations were exposed to artificial cerebrospinal fluid equilibrated with severe or mild hypoxia for 90 minutes. Inhibitory and excitatory neurotransmitter antagonists were added to artificial cerebrospinal fluid to investigate synaptic transmission. The artificial cerebrospinal fluids containing various concentrations of glucose were used to study the glucose's effects. RESULTS: Ventral root motor-evoked potential consisted of the early and late components, which were excitatory transsynaptic potentials. The amplitudes were increased in the early phase of severe hypoxia and declined in the prolonged exposure. In mild hypoxia, there was a sustained increase of the amplitudes. The application of inhibitory neurotransmitter antagonists abolished the augmentation of the amplitudes in the early phase of severe hypoxia. Hypoxia without glucose accelerated hypoxic change. CONCLUSION: Inhibitory synaptic transmission was depressed preferentially in the early phase of severe hypoxia or in mild hypoxia. Excitatory and inhibitory transmissions were suppressed in prolonged severe hypoxia. Glucose deficiency aggravated hypoxic inhibition of synaptic transmissions.

Animals↗

PubMed1996

Long exposure to high glucose concentration impairs the responsive expression of gamma-glutamylcysteine synthetase by interleukin-1beta and tumor necrosis factor-alpha in mouse endothelial cells.

To elucidate the pathological metabolism of glutathione synthesis in diabetic endothelial cells, we studied the expression of gamma-glutamylcysteine synthetase (gamma-GCS) using a mouse vascular endothelial cell line. Exposing normoglycemic endothelial cells to tumor necrosis factor-alpha (TNF-alpha) or interleukin-1beta (IL-1beta) increased the activity and the mRNA expression of gamma-GCS. The addition of inhibitors for nuclear factor kappaB (NF-kappaB) to the cells caused a loss of the gamma-GCS mRNA expression in response to TNF-alpha. A shift of the concentration of glucose in the medium from 5.5 to 28 mM glucose and a following incubation for 7 days decreased the expression of gamma-GCS mRNA. These cells showed no apparent responses of gamma-GCS mRNA or the activity of NF-kappaB to TNF-alpha or IL-beta. Increase in the GSH concentration of the cells treated with 28 mM glucose restored the expression of gamma-GCS mRNA and its response to TNF-alpha or IL-beta, suggesting that redox regulation is involved in the expression of gamma-GCS. In summary, the expression of gamma-GCS is regulated by TNF-alpha or IL-1beta in endothelial cells mediated by NF-kappaB stimulation, and impairment of the regulation of gamma-GCS in hyperglycemic cells may be a cause of medical complications that develop in diabetes mellitus.

Adenosine Triphosphate↗

PubMed1996

Relation of oxidative stress and glutathione synthesis to CD95(Fas/APO-1)-mediated apoptosis of adult T cell leukemia cells.

An IL-2 dependent adult T cell leukemia cell line (SO4) has been established that is sensitive to CD95-mediated apoptosis as well as a subline (R-SO4) that is resistant. Incubating SO4 cells with anti-CD95 IgM mAb caused concentration-dependent cell death. On the contrary, R-SO4 cells did not die even at 1000 ng/ml of anti-CD95 IgM mAb. The levels of CD95 expression on R-SO4 cells were one-third of those on SO4 cells. However a blocking Ab, anti-CD95 IgG mAb, did not induce complete resistance of SO4 cells to anti-CD95 IgM mAb as R-SO4 cells. As CD95 and TNF receptor are similar, and TNF/TNF receptor binding induces oxygen radicals, the involvement of oxidant and antioxidant systems in CD95-mediated apoptosis has been examined. The addition of anti-CD95 IgM mAb resulted in formation of intracellular oxygen radical species in the SO4 cells as measured using 2',5',-dichlorofluorescein as substrate. The oxygen radical production induced DNA damage as determined by formation of 8-hydroxydeoxyguanosine. No increase in the formation of oxygen radicals was observed in R-SO4 cells. Concentrations of the intracellular antioxidant, glutathione, and the key enzyme for its synthesis, gamma-glutamylcysteine synthetase, were 150% increased in R-SO4 cells in comparison with that of SO4 cells. Moreover, glutathione ester decreased the formation of 8-hydroxydeoxyguanosine. These results suggested that apoptosis mediated by CD95 in ATL cells is related to the production of oxygen radical species and cellular antioxidant systems, especially, glutathione synthesis.

Apoptosis↗

PubMed1996

Novel immunosuppressive proteins purified from the serum of liver-retransplanted rats.

Liver grafts between certain rat strain combinations, such as DA (RT1a)-into-PVG (RT1c), are accepted without the use of immunosuppressive agents. To explore the nature and role of serum proteins in liver-induced immunosuppression, we have developed a retransplantation model of rat liver grafting. In this procedure, orthotopic liver transplantation (OLT) is carried out in the DA-into-PVG combination; two days later the DA liver is removed and a new PVG liver implanted into the same recipient (re-OLT). Serum from re-OLT rats was immunosuppressive when tested in mixed lymphocyte reactions (MLR). Three novel proteins were detected in re-OLT serum by SDS-PAGE, with sizes of 180 kD, 87 kD, and 10 kD. The N-terminal sequences of these were distinct and did not match protein sequences in the computer databases, although there was some homology between the 10 kD sequence and the beta-chain of rat hemoglobin. Purified 87 kD and 10 kD proteins were immunosuppressive in MLR; in both cases suppression was dose-dependent and nonstimulator-specific. Production of the 180 kD and 87 kD molecules required the presence of the recipient spleen. We conclude that re-OLT serum contains novel immunosuppressive proteins, which may be products of immune recognition and associated with the immediate termination of graft rejection.

Amino Acid Sequence↗

PubMed1996

Conformational changes in the A1 domain of von Willebrand factor modulating the interaction with platelet glycoprotein Ibalpha.

The interaction between von Willebrand factor (vWF) A1 domain and platelet glycoprotein Ib alpha occurs in the presence of high shear stress or when vWF becomes immobilized onto a surface but not appreciably in the normal circulation. To investigate the structural properties regulating A1 domain function, we have used recombinant fragments prepared either in cyclic form with oxidized Cys509-Cys695 disulfide bond or reduced and alkylated. Interaction with glycoprotein Ibalpha was assessed by testing inhibition of monoclonal antibody LJ-Ib1 binding to platelets and inhibition of shear-induced platelet aggregation mediated by native vWF. Fragments exposed to pH between 2.5 and 3.5 adopted the molten globule conformation with loosened tertiary structure intermediate between native and completely unordered state. Maximal receptor binding activity was observed when fragments kept at acidic pH, particularly after reduction of the Cys509-Cys695 disulfide bond, were subjected to quick refolding by rapid pH increase. In contrast, slow refolding by incremental pH change over several hours resulted in at least 20-fold lower activity. A specific single point mutation (I546V) resulted in enhanced receptor binding, whereas another mutation (S561G) caused markedly reduced binding. These results provide experimental evidence that conformational transitions can modulate function of the vWF A1 domain in solution.

Alkylation↗

PubMed1996

Detailed modified technique for safer harvesting and preparation of liver graft in the rat.

Liver procurement and preparation for orthotopic liver transplantation (OLT) in the rat is the first stage for beginners aiming to acquire mastery of this model. It requires extensive and precise dissection in which each detail must provide security for the procurement and perfection for the future graft. Many technical details, "tricks and secrets," remain known only by expert teams, so that the learning phase can be long or unsuccessful if a period in such a team is not possible. We describe this procedure in great detail, including many improvements to the original technique. Complete illustration is provided to enable an easier appreciation of what remains the critical first part of the most difficult transplant model to perform in the rat.

Animals↗

PubMed1996

Restoration of tolerance to rat hepatic allografts by spleen-derived passenger leukocytes.

The tolerance induced by orthotopic liver transplantation (OLT) in certain combinations of rat strains can be prevented by total body irradiation (TBI) of the donor. We demonstrate here that the intravenous inoculation of splenic leukocytes into irradiated donors before OLT could re-establish tolerance in association with a state of microchimerism detected in the recipients. When donor DA (RT1a) strain rats were irradiated with 1000 rad 24 h before liver harvesting and subsequent liver implantation into PVG recipients, five out of six rats died from rejection in this normally tolerogenic OLT (DA-PVG) combination. Injection of 1.5 x 10(8) splenic leukocytes from naive DA rats into the irradiated DA donor rats 24 h before OLT restored the tolerogenic potential of the liver allografts. Immunofluorescence assay revealed an increased number of donor (DA) type cells in the PVG recipient bearing a repopulated DA liver, compared to the PVG recipient of an irradiated liver. These results suggest that passenger leukocytes reconstituted by splenic leukocytes have the capacity to protect liver allografts.

Animals↗

PubMed1996

The beneficial effect of the prostacyclin analogue (OP 2507) on rat liver transplantation subjected to an extended anhepatic phase.

We investigated the effect of a prostacyclin analogue (OP 2507) on PVG (RT1c) recipients subjected to an extended anhepatic phase (AH) and transplanted orthotopically with PVG livers. All of the animals that underwent orthotopic liver transplantation (OLT) with a 20-min AH survived for 1 week with or without OP 2507, (OP) treatment (10/10, 100%). When the AH was lengthened to 45 min, the 1-week survival rate of recipients was poor in the OP-untreated groups (1/10, 10%). Treatment of the recipient with OP 2507, 0.15 micrograms/kg per minute for 30 min, prior to the 45-min AH substantially improved 1-week survival (5/6, 83.3%, P < 0.05). The serum TNF-alpha level at day 1 in OP-treated animals that underwent OLT with a 45-min AH was significantly lower than that in animals with 45-min AH OLT without OP treatment. We conclude that OP 2507 treatment has potential usefulness as a perioperative treatment when the AH is extended during OLT.

Animals↗

PubMed1996

Comparison between menopause-related changes in bone mineral density of the lumbar spine and the proximal femur in Japanese female athletes: a long-term longitudinal study using dual-energy X-Ray absorptiometry.

This longitudinal study examined whether bone mineral density (BMD) of the lumbar spine and the proximal femur is maintained in pre-, peri-, and postmenopausal women by regular exercise. BMD was measured using dual-energy X-ray absorptiometry (DXA). Twenty-six Japanese women (mean age 47.8 years) were followed 4-5 years. Twenty-two subjects from volleyball or jogging clubs had participated in the same exercise for more than 5 years at the initial BMD measurement. Longitudinally, for these 22 athletes, the rate of change per year in BMD of the lumbar spine was -0.17% in the premenopause group and -2.60% in the perimenopause group. In the proximal femur of the athletes, BMD increased (rate of increase per year 1.80%) in the premenopause group, but decreased (rate of decrease per year 1.07%) in the perimenopause group. In the premenopause group, BMD of the proximal femur increased in all athletes. However, in the proximal femur, the nonexercise group showed a 0.31% decrease, a significant difference (P < 0.05) compared with the athletes. These findings suggest that women can achieve continuous gains in bone mass in the proximal femur before menopause by regular intense exercise. However, continued high-level physical activity in the perimenopausal women was not able to prevent bone loss.

Absorptiometry, Photon↗

PubMed1996

Alterations of local cerebral blood flow, phorbol 12,13-dibutyrate binding activity, and histological damage during acute focal ischaemia in rat brain. A pathophysiology of acute focal ischaemia: Part 1.

The alterations of the local cerebral blood flow (LCBF), 3H-phorbol 12,13-dibutyrate (PDBu) binding activity were measured, and histological findings were also examined during the closed time course (0, 1, 3, 5, 7 hour) after middle cerebral artery occlusion (MCAO) in rat brain to assess the complex pathophysiology of acute focal ischaemia. From 1 to 3 hours after the start of MCAO, significant (p < 0.01) hyperreactivity of the second messenger system involving PDBu binding may be present, despite low perfusion of LCBF, and severe damage in the striatum whereas sparing almost completely the cortex on histological examination. At 5 hours, the PDBu binding activity increased slightly but not significantly but is reduced markedly at 7 hours after MCAO compared with the control group. The measurement of PDBu binding activity, additionally to measuring the LCBF and observation of the histological change might be a useful indicator in determining the threshold and duration of ischaemia which cause functionally irreversible cell damage in the brain.

Animals↗

PubMed1996

Cytochrome oxidase activity during acute focal ischaemia in rat brain. A pathophysiology of acute focal ischaemia: Part 2.

An enzyme-histochemical technique was used to examine the changes in cytochrome oxidase activity during acute focal ischaemia in the rat. In the somatosensory cortex, the enzyme activity began to increase significantly (p < 0.01) 1 hour after middle cerebral artery occlusion (MCAO) and continued to increase up to 3 hours, during which ischaemic cell damage was not detected. In the striatum, the enzyme activity increased significantly (p < 0.01) 1 hour after MCAO in the absence of morphological evidence of ischaemic cell damage; a peak activity was reached at 2 hours, and began to decline 3 hours after MCAO when moderate ischaemic change was detected. In both cortical and subcortical areas, the enzyme activity tended to decrease from 4 hours after MCAO, and was reduced to a level similar to or below that of the non-ischaemic hemisphere 5 hours after MCAO, when severe ischaemic damage was demonstrated. The relation of this transient increase of cytochrome oxidase activity in the early stage of acute ischaemia and the hypermetabolism of neuronal cells during ischaemic insult was discussed.

Animals↗

PubMed1996

Mechanistic analysis of high antitumor effect of intradermal administration of lipopolysaccharide from Pantoea Agglomerans.

Lipopolysaccharide from Pantoea Agglomerans (LPSp) has a remarkably high antitumor activity even against poorly immunogeneic tumors when given by intradermal injection combined with cyclophosphamide (CY). We have extended this study to gain an insight into the mechanism of this antitumor effect, and especially into the induction of cell mediated immunity. In immunohistological studies, extensive necrosis and marked infiltration of the inflammatory cells at the tumor were observed after intradermal injection of LPSp combined with CY, but not after CY alone or after no treatment. The cells around the tumors were mostly neutrophils and macro phages (Mac 1+); T cells (CD4+, CD8+) were also present. The serum levels of cytokines, induced after intradermal injection of LPSp, were determined and compared with intravenous administration of LPSp or recombinant TNF-SAM2. TNF-alpha, IL-1, IL-6 and GM-CSF were measured by ELISA as a marker of cytokine induction. The peak level of TNF-alpha induced by intradermal injection of LPSp was about 5000 pg ml-1, which was considered relatively small since this level was observed even in clinical trial. There seems to be a longer period of release of TNF-alpha after an intradermal injection than after an intravenous injection. This may produce the remarkably high antitumor effect of the intradermal injection. The antitumor effect of intradermal administration combined with CY was evaluated in nude mice to clarify the role of T cells in high antitumor activity. In this experiment, antitumor activity was found to be much less in BALB/c nu/nu mice without regression, while complete regression was frequently observed in syngeneic mice, showing the crucial role of T cells in this treatment. These observations suggest that intradermal administration of LPSp in combination with CY continuously releases and induces not only extensive necrosis of the tumor but also cell mediated antitumor immunity, which may be indispensable for complete regression of the tumor. Clinical application of this treatment for advanced cancer patients is in progress.

Animals↗