Biomedical subjects

Hitoshi Sato

Publications and source records attributed to Hitoshi Sato.

At least 37 records · Page 2Linked to original sources

PubMed2004

Selective inhibition of bleomycin-induced G2 cell cycle checkpoint by simaomicin alpha.

Human T-cell leukemia-derived Jurkat cells are known to be defective in the G1 checkpoint. DNA-damaging agent bleomycin arrests the cell cycle at G2 phase of Jurkat cells, and microtubule-acting colchicine arrests it at the M phase. Simaomicin alpha, an actinomycete metabolite, itself showed no effect on the cell cycle status of Jurkat cells at least up to 6.0 nM. However, the compound (0.6-6.0 nM) was found to abrogate the bleomycin-induced G2 arrest, yielding a drastic decrease in cells at the G2 phase and increase in cells at the subG1 and G1 phases. On the other hand, the compound did not show any effect on the colchicine-induced M phase arrest in Jurkat cells. Furthermore, the compound showed almost no effect on the cell cycle status of the bleomycin-treated or -untreated normal cell line HUVEC. These data suggested that simaomicin alpha disrupts the cell cycle G2 checkpoint of cancer cells selectively, leading to sensitization of cancer cells to anti-cancer reagents.

Bleomycin↗

PubMed2004

Properties of horizontal semicircular canal nerve-activated vestibulospinal neurons in cats.

Axonal pathways, projection levels, and locations of horizontal semicircular canal (HC) nerve-activated vestibulospinal neurons were studied. The HC nerve was selectively stimulated. Vestibulospinal neurons were activated antidromically with four stimulating electrodes, inserted bilaterally into the lateral vestibulospinal tracts (LVST) and medial vestibulospinal tracts (MVST) at the C1/C2 junction. Stimulating electrodes were also positioned in the C3, T1, and L3 segments and in the oculomotor nuclei. Most HC nerve-activated vestibulospinal neurons were located in the ventral portion of the medial, lateral, and the descending nuclei. Among the 157 HC nerve-activated vestibular neurons, 83 were antidromically activated by stimulation at the C1/C2 junction. Of these 83 neurons, axonal pathways of 56 HC nerve-activated vestibulospinal neurons were determined. Most (48/56) of these had axons that descended through the MVST, with the remainder (8 neurons) having axons that descended through the ipsilateral (i-) LVST. Laterality of the axons' trajectories through the MVST was investigated. The majority of vestibulospinal neurons (24/28) with axons descending through the contralateral MVST were also antidromically activated from the oculomotor nucleus, whereas almost all vestibulospinal neurons (19/20) with axons descending through the i-MVST were not. Most HC nerve-activated vestibulospinal neurons were activated antidromically only from the C1/C2 or C3 segments. Only one neuron that was antidromically activated from the T1 segment had an axon that descended through the i-LVST. None of the HC nerve-activated vestibulospinal neurons were antidromically activated from the L3 segment. It is likely that the majority of HC nerve-activated vestibulospinal neurons terminate in the cervical cord and have strong connections with neck motoneurons.

Animals↗

PubMed2004

Eye movements evoked by selective saccular nerve stimulation in cats.

OBJECTIVE: Because of technical obstacles in controlling current spread to adjacent peripheral nerve, eye movements evoked by activation of the otolith organs have not been investigated in detail compared to eye movements evoked by activation of the canal organs. We attempted to solve this problem by applying more sensitive methods using fine needle and strictly controlling stimulus current intensity compare with filed potential for selective stimulation. METHODS: Eye movements evoked by selective, unilateral saccular (SAC) nerve stimulation were investigated using both electrooculography (EOG) and video recording in decerebrated cats in the presence or absence of anesthesia. Electrical stimulation was applied to the SAC nerve through implanted acupuncture needles. RESULTS: In the absence of anesthesia and with stimulus intensities less than (3.1 +/- 2.7) x N(1)T, we found supraduction in both eyes or in either the ipsilateral or contralateral eye of different cats. We observed downward eye movements using a stronger stimulus intensity ((6.2 +/- 2.9)) x N(1)T). The threshold for downward eye movements was significantly greater than that for upward eye movements (P < 0.05). In anesthetized cats, only downward eye movements were observed when stimulus intensities less than 10 x N(1)T ((7.8 +/- 2.3) x N(1)T) were used. CONCLUSION: These results confirm the known sacculo-ocular anatomical connections, which are involved predominantly in vertical eye movements. Because the sacculo-ocular connections are relatively weak, the normal supraduction evoked by SAC activation can be easily modified by factors such as level of anesthesia and the method of stimulation.

Animals↗

PubMed2004

Promoter polymorphism in the CD14 gene and concentration of soluble CD14 in patients with in-stent restenosis after elective coronary stenting.

BACKGROUND: Activated monocytes/macrophages, neutrophils, endothelial cells and smooth muscle cells participate in the restenosis processes. Monocytes/macrophages and neutrophils are activated by lipopolysaccharide (LPS) via CD14. Endothelial cells and smooth muscle cells are also stimulated by soluble CD14 (sCD14)-LPS complexes. METHODS: We tested the hypothesis that C(-260)-->T polymorphism of the CD14 gene and sCD14 might be predictors for in-stent restenosis. We analyzed 129 consecutive patients who underwent elective coronary stenting. The restenosis was defined as > or =50% diameter stenosis at follow-up angiography. RESULTS: The prevalence of the T/T genotype and the concentration of sCD14 were significantly higher in the restenosis group than in the no-restenosis group. This CD14 polymorphism also affected the levels of sCD14, therefore, we divided the patients into four groups. The loss index was 24.8% in C/C or C/T and < or =50th percentile of sCD14, 35.9% in T/T and < or =50th percentile of sCD14, 44.2% in C/C or C/T and >50th percentile of sCD14, and 49.1% in T/T and >50th percentile of sCD14 (P=0.02). The restenosis rate was 10.0%, 26.7%, 26.2% and 50.0% in each group, respectively (P=0.003). In the multivariate analysis, T/T and >50th percentile of sCD14 was the independent predictor for in-stent restenosis. CONCLUSIONS: This study showed that the T/T genotype with a high level of sCD14 is an independent predictor of in-stent restenosis. The activation of monocytes/macrophages, endothelial cells and smooth muscle cells mediated by CD14 and/or sCD14 may play an important role in the restenosis processes.

Angina Pectoris↗

PubMed2004

Herpes simplex virus-induced, death receptor-dependent apoptosis and regression of transplanted human cancers.

Inoculation of a live attenuated herpes simplex virus (HSV) vector, betaH1, into human U87MG glioblastoma cells transplanted into athymic nude mice induced complete regression of tumors. The infected cells underwent histochemically confirmed apoptosis without lymphocyte infiltration after expressing CD30, CD30 ligand (CD30L), tumor necrosis factor (TNF)-alpha, TNF receptor 1 (TNF-R1), FAS, and FAS ligand (FAS-L) with activation of caspases 3 and 8. Induction of the transcripts of these receptors and ligands in inoculated tumors was confirmed by quantitative RT-PCR. To examine the specificity of apoptosis in the transplanted tumor, we inoculated betaH1 into transplanted human lung, breast, gastric, and colon cancer tumors, and similar tumor regression with apoptosis was observed in all tumors. We analyzed the roles of expression of CD30, CD30L, TNF-alpha, TNF-R1, FAS, and FAS-L in the tumors, and found that HSV-induced apoptosis was suppressed by the respective antibodies. These findings indicate that the CD30/CD30L, TNF-alpha/TNF-R1, and FAS/FAS-L interactions resulted in apoptosis and tumor regression in immunocompromised mice. In addition to the death receptor-dependent apoptosis induced by HSV, the expressed ligands and receptors might enhance the susceptibility of tumor cells to cell-mediated cyto-toxicity and augment the activation of tumor-killing lymphocytes in immunocompetent models.

Animals↗

PubMed2004

In vitro and in vivo correlation of the inhibitory effect of cyclosporin A on the transporter-mediated hepatic uptake of cerivastatin in rats.

Previously, we have shown that the inhibition of the transporter-mediated hepatic uptake of cerivastatin (CER) by cyclosporin A (CsA) could, at least partly, explain a pharmacokinetic interaction between these drugs in humans. In the present study, we have examined the effect of CsA on the in vivo disposition of CER in rats and the in vitro uptake of [14C]CER in isolated rat hepatocytes in an attempt to evaluate the effect of inhibition of transporter-mediated hepatic uptake on the in vivo CER disposition. The steady-state plasma concentration of CER increased 1.4-fold when coadministered with CsA up to a steady-state blood concentration of 4 microM. Studies of [14C]CER uptake into isolated rat hepatocytes showed saturable transport, with the saturable portion accounting for more than 80% of the total uptake. CsA competitively inhibited the uptake of [14C]CER with a Ki of 0.3 microM. The IC50 for the uptake of [14C]CER in the absence and presence of rat plasma was 0.2 and 2.3 microM, respectively. The in vivo hepatic uptake of [14C]CER evaluated by the liver uptake index method was also inhibited by CsA in a dose-dependent manner. On the other hand, CsA did not inhibit the metabolism of [14C]CER in rat microsomes. The in vitro and in vivo correlation analysis revealed that this pharmacokinetic interaction between these drugs in rats could be quantitatively explained by the inhibition of transporter-mediated hepatic uptake. Thus, this drug-drug interaction in rats is predominantly caused by the transporter-mediated uptake process.

Algorithms↗

PubMed2004

Effect of probucol on neointimal thickening in a stent porcine restenosis model.

Restenosis after stent deployment remains a major clinical problem. Antioxidants have been proposed as a promising strategy against restenosis. We tested the antioxidant probucol for its efficacy against neointimal hyperplasia in porcine coronary arteries after stent implantation. Probucol was then tested in vivo in 8 coronary arteries of 4 pigs (1000 mg/day orally beginning 7 days before stenting) and was compared to placebo (10 coronary arteries, 5 pigs) 28 days after stenting. Quantitative intravascular ultrasound (IVUS) revealed 38.8 +/- 4.0 versus 40.1 +/- 3.0% area stenosis in the probucol versus control group. Histopathologic assessment showed that probucol had no beneficial effect on inhibiting the neointimal proliferative response in stent lesions compared to placebo (2.35 +/- 0.26 versus 2.88 +/- 0.25 mm(2)), despite similar injury scores (1.20 +/- 0.12 versus 1.28 +/- 0.14). An edge segment (axially 2-mm proximal to the stent margins) was assessed by IVUS. Remodeling index, which is a good marker of constrictive remodeling, was defined by the ratio of the vessel area in the lesion site (stent edge) to the vessel area in the proximal reference site (6-mm proximal to the stent margins). The remodeling index was significantly larger in the probucol group that in the placebo group (1.18 +/- 0.10 versus 0.90 +/- 0.06, P = 0.0012). In conclusion, probucol reduced constrictive remodeling at the edge of the implant but did not inhibit the tissue response within the stent.

Animals↗

PubMed2004

Boromycin abrogates bleomycin-induced G2 checkpoint.

The DNA-damaging agent bleomycin arrests the cell cycle at the G2 phase of Jurkat cells defective in the G1 checkpoint, and microtubule-acting colchicine arrests it at the M phase. Boromycin itself, an actinomycete metabolite, showed no effect on the cell cycle status of Jurkat cells at least up to 340 nM. However, the compound (3.4-340 nM) was found to abrogate bleomycin-induced G2 arrest even at 3.4 nM, resulting in a drastic decrease in cells at the G2 phase and increase in cells at the subG1 phase. On the other hand, boromycin did not show any effect on the colchicine-induced M phase arrest in Jurkat cells, nor on the cell cycle status of the bleomycin-treated or -untreated HUVEC, normal cells conserving both G1 and G2 checkpoints. Furthermore, boromycin potentiated anti-tumor activity of bleomycin in scid mice inoculated with Jurkat cells. These data suggest that boromycin disrupts the cell cycle at the G2 checkpoint of cancer cells selectively, leading to sensitization of cancer cells to anti-cancer reagents.

Animals↗

PubMed2003

Superiority of varicella skin test antigen over purified varicella-zoster virus glycoproteins in monitoring booster response to Oka varicella vaccine.

Varicella skin test antigen has been developed based on the induction of delayed-type hypersensitivity (DTH) to varicella-zoster virus (VZV). The booster immune response to Oka varicella vaccine was assessed by cutaneous reactivity to purified VZV glycoprotein complexes, gB, gE:gI, gH:gL, and varicella skin test antigen. Skin tests with these antigens significantly augmented antibody production to glycoproteins and VZV antigen resulting in no further augmentation by the subsequent vaccination. All glycoprotein complexes induced the cutaneous reaction similarly to varicella skin test antigen. Cutaneous reaction to glycoproteins and varicella skin test antigen was boosted after vaccination. However, the magnitude of cutaneous reaction to each glycoprotein complex before and after vaccination was rich in variety. These results indicated that skin test with varicella skin test antigen is a more suitable indicator in monitoring cell-mediated immunity to VZV than that using purified glycoproteins.

Adult↗

PubMed2003

Protective effects of glutathione on 5-fluorouracil-induced myelosuppression in mice.

The protective effects of glutathione (GSH) administration on myelosuppression induced by 5-fluorouracil (5-FU) were investigated in female BALB/c mice. Animals were allocated to four groups (16 mice/group). GSH was given orally at a dose of 800 mg/kg to groups 3 and 4 for 21 consecutive days (day 0 to day 20). 5-FU was repeatedly administered at a dose of 40 mg/kg to groups 2 and 3 for 1 week (day 7 to day 13) by gavage. Group 3 served as a combined treatment group and group 1 as a non-treated control group. The total observation period was 3 weeks. Body weight was measured once a week. A decrease in body weight due to 5-FU treatment was observed in groups 2 and 3 on day 14. Although the body weight in group 2 had not increased by 1-week after cessation of 5-FU treatment, the value in group 3 markedly recovered. Hematology, total nucleated myelocyte count and histopathology of bone marrow were carried out on day 14 and day 21. In groups 2 and 3, these examinations showed thrombocytopenia, leukopenia, reticulocytopenia and myelosuppression on day 14. However, platelets and bone marrow were less affected in group 3 than in group 2. On day 21, the thrombocytopenia in groups 2 and 3 was resolved. The myelosuppression, leukopenia and reticulocytopenia resolved in group 3, but not in group 2. Although simple microcytic anemia occurred delayed on day 21, it was less severe in group 3 than in group 2. Therefore, GSH may have preventive effects against 5-FU-induced hematopoietic toxicity, and accelerate recovery after cessation of 5-FU treatment.

Administration, Oral↗

PubMed2003

Potentiation of domperidone-induced catalepsy by a P-glycoprotein inhibitor, cyclosporin A.

The distribution of domperidone (DOM), a peripheral dopamine D(2) receptor antagonist, to the brain is restricted by P-glycoprotein (P-gp) at the blood-brain barrier (BBB) and for this reason, DOM rarely causes parkinsonian symptoms, such as extrapyramidal side effects (EPS), unlike other dopamine D(2) antagonists. In this study, we aimed to investigate whether cyclosporin A (CsA), a P-gp inhibitor, potentiates EPS induced by DOM. The intensity of EPS was assessed in terms of the duration of catalepsy in mice. D(1), D(2) and mACh receptor occupancies at the striatum were measured in vivo and in vitro. Moreover, the distribution of DOM to the brain was investigated by using an in situ brain perfusion technique. The intensity of DOM-induced catalepsy was significantly potentiated by the coadministration of CsA. The in vivo occupancies of D(1), D(2) and mACh receptors, as well as the brain distribution of DOM, were increased by CsA. These results suggest that CsA increases the brain distribution of DOM by inhibiting P-gp at the BBB, and potentiates catalepsy by increasing the occupancies of the D(1) and D(2) receptors. The risk of DOM-induced parkinsonism may be enhanced by the coadministration of CsA.

ATP Binding Cassette Transporter, Subfamily B, Mem↗

PubMed2003

Induction of cellular immunity to varicella-zoster virus glycoproteins tested with pernasal coadministration of Escherichia coli enterotoxin in mice.

A mutant of Escherichia coli enterotoxin promotes the induction of cellular immunity to a live varicella vaccine (the Oka strain) as a mucosal adjuvant in mice. An investigation was carried out to determine which of the purified glycoproteins of the virus among three induced cellular immunity with a single nasal administration. Spleen cells from mice immunized nasally with the vaccine and toxin produced interleukin-2 (IL-2) at the same level on restimulation in vitro with glycoprotein H: glycoprotein L (gH:gL), gB, and gE:gI, but not IL-4. The spleen cells from mice immunized with gH:gL, gB, or gE:gI and toxin produced IL-2 on restimulation with gH:gL, gB, or gE:gI, respectively, and the vaccine, but not IL-4. Immunization with gH:gL and the toxin showed increased thymidine uptake and production of IL-2 and interferon-gamma (IFN-gamma) of the spleen cells, but not IL-4, depending on the dose of gH:gL used for immunization and restimulation in vitro. Purified gE:gI and gB have been reported to be the strongest stimulators of cellular immunity to varicella upon subcutaneous injection and are useful as a subunit vaccine. All the glycoproteins tested are excellent stimulators of cellular immunity to the virus and itself on nasal co-immunization with the toxin.

Adjuvants, Immunologic↗

PubMed2003

Use of a rodent model to show that varicella-zoster virus ORF61 is dispensable for establishment of latency.

Varicella-zoster virus (VZV) results in a latent infection in humans after primary infection. Latency has also been established in guinea pigs and rats after inoculation with the virus. It was found that infection of cotton rats with the Oka vaccine strain of VZV results in a latent infection. To begin to identify which genes are required for latency, we infected cotton rats with VZV strain Oka that is deleted for ORF61. ORF61 protein transactivates certain VZV promoters and enhances the infectivity of viral DNA in transient transfections. Deletion of ORF61 results in abnormal syncytia and impairs the growth of VZV in vitro. Inoculation of cotton rats with ORF61-deleted Oka virus resulted in latent VZV infection in the nervous system similar to that seen for animals infected with parental virus. Thus, the cotton rat can be used to study the ability of mutants in the Oka vaccine strain of VZV to establish latent infection.

Animals↗

PubMed2003

Pharmacokinetic and pharmacodynamic analyses, based on dopamine D2-receptor occupancy of bromocriptine, of bromocriptine-induced contralateral rotations in unilaterally 6-OHDA-lesioned rats.

Bromocriptine is a selective agonist for dopamine D2-receptors and is used in the treatment of Parkinson's disease. In this study, we performed pharmacokinetic and pharmacodynamic (PK/PD) analyses of the antiparkinsonian effect of bromocriptine and evaluated drug-induced contralateral rotations in rats in which unilateral striatal lesions had been generated by microinjection of 6-hydroxydopamine (6-OHDA) into the medial forebrain bundle. The plasma concentration (Cp) and D2 receptor occupancy (Phi(D2)) were quantitated by HPLC and with an in vivo back-titration method using [(3)H]-raclopride, respectively. Bromocriptine induced contralateral rotations (E(rot)) in a dose-dependent manner following intraperitoneal administration in an animal model of Parkinson's disease. The Cp of bromocriptine peaked at 15-30 min after the administration and decreased time-dependently, whereas the Phi(D2) of bromocriptine increased gradually for 180 min after administration. The relationship between Cp and E(rot) exhibited an anticlockwise hysteresis, whereas the relationship between Phi(D2) and E(rot) showed a linear correlation. These results suggest that in vivo Phi(D2) is a good pharmacological indicator of the effect of a D2 agonist.

Animals↗

PubMed2003

Eye movements evoked by the selective stimulation of the utricular nerve in cats.

OBJECTIVE: Eye movements evoked by otolith organ are not well-investigated compare with canal related eye movements due to the technical difficulties. We try to solve this problem by means of our methods. METHODS: Eye movements evoked by selective utricular (UT) nerve stimulation were investigated using both electrooculography (EOG) and video recording in decerebrated cats in the presence or absence of anesthesia. Electrical stimulation was applied to the UT nerve through implanted acupuncture needles. RESULTS: In the absence of anesthesia and with stimulus intensities less than 2.6+/-0.7 x N(1)T, we found ipsilaterally directed horizontal eye movements in both eyes in one cat, abduction in the ipsilateral eye in two cats, and adduction in the contralateral eye in another cat. Other types of eye movements (e.g., supraduction or diagonal eye movements) were observed in both eyes of cats in the absence of anesthesia at a stimulus intensity of 12.2+/-7.6 x N(1)T, an intensity in which current spread to the adjacent nerve could not be ruled out. In the presence of anesthesia, UT nerve stimulation alone failed to evoke horizontal eye movements, but with an intensity 13.8+/-6.4 x N(1)T, supraduction or diagonal eye movements were evoked. UT nerve stimulation at 2-3 x N(1)T facilitated horizontal eye movements induced by ipsilateral abducens (AB) nucleus stimulation or contralateral horizontal canal nerve stimulation. CONCLUSION: This is the first report to our knowledge in which UT nerve-evoked horizontal eye movements are documented. These results confirm the known monosynaptic and disynaptic anatomical connections from utricular primary afferents to the ipsilateral AB nucleus neurons.

Abducens Nerve↗

PubMed2003

Projections from the nucleus reticularis magnocellularis to the rat cervical cord using electrical stimulation and iontophoretic injection methods.

The aim of this study is to clarify the fiber distribution of the nucleus reticularis magnocellularis (NRMC) and adjacent areas in the rat spinal cord. Biotinylated dextran amine was injected iontophoretically through a glass capillary into the areas, in which a single cell responded to noxious electrical stimulation of the sciatic nerve and to a pinch of the thigh skin with multiple spikes. Labeled fibers descended bilaterally through the ventral funiculi of the medulla oblongata and then through the ventral and lateral funiculi of the cervical cord with an ipsilateral predominance, and terminated in the spinal gray (laminae I-X). A single fiber sometimes ran through several laminae while bifurcating many short branches with axon varicosities and terminal buttons in one transverse section, that is, through laminae V, VII and X, through laminae V, IIl-IV and I-II, and through laminae VII to I-II. The present study showed that the wide distribution of a single fiber and a mass of fibers descending from the NRMC and adjacent areas might modulate not only somatic sensory and motor functions but also autonomic functions in the spinal cord.

Action Potentials↗

PubMed2003

Nuclear gene sequences and DNA variation of Cryptomeria japonica samples from the postglacial period.

Genomic DNA was extracted from heartwood blocks of six Cryptomeria japonica individuals that had been buried (in an area now covered by rice fields) for about 3600 years. Attempts were made to determine the sequences of five nuclear genes following polymerase chain reaction amplification, using previously obtained C. japonica expressed sequence tag (EST) information. We detected 15 nucleotide substitutions and four insertion/deletions (indels) in a partial GapC gene sequence among 13 individuals of the buried and an extant population, which allowed us to estimate the extent of DNA variation within the buried populations, and the level of genetic differentiation between the buried population and the extant population growing in a neighbouring area. For the entire haplotypes of the GapC region, pi and theta nucleotide diversity estimates were 0.0063 and 0.0010, respectively, when both populations were included, while corresponding figures for the buried population alone were 0.0009 and 0.0017. Estimates of DNA divergence statistics (dXY = 0.0062, dA = 0.0005, FST = 0.0832 and KST = 0.0935) suggest that differentiation between the two populations was not great. However, permutation tests gave FST and KST values rejecting the null hypothesis (that populations were not differentiated) at the 5% and 1% probability levels, respectively. The significant genetic differentiation between the two populations was mainly caused by differences in haplotype diversity. The significant level of haplotype diversity in the extant population compared to the buried population might be the result of gene flow from neighbouring artificial forests. Alternatively, it is possible that we failed to detect all the DNA variation in the buried population because of clonal growth in the buried population.

Base Sequence↗

PubMed2003

Induction of humoral and cell-mediated immunity to hepatitis B surface antigen by a novel adjuvant activity of Oka varicella vaccine.

Oka varicella vaccine induces humoral and cell-mediated immunity to varicella-zoster virus (VZV), even in immunocompromised hosts. This vaccine showed novel adjuvant activity against co-inoculated hepatitis B surface antigen (HBsAg). Either a mixed inoculation of HBsAg with heat-inactivated Oka varicella vaccine at one site or a separate inoculation of HBsAg and live vaccine at different sites induced an antibody response but failed to induce delayed type hypersensitivity (DTH) to HBsAg. In contrast, immunization of HBsAg mixed with live vaccine induced DTH and an enhanced antibody response to HBsAg. The adjuvant activity of Oka varicella vaccine was similar in terms of antibody production to that of alum adjuvant. A T helper cell-dominant immunity to VZV and HBsAg continued for 1 year. Oka varicella vaccine combined with a foreign antigen may serve as a novel polyvalent vaccine for the infectious diseases for which cell-mediated immunity is beneficial.

Adjuvants, Immunologic↗