Biomedical subjects

Y Kitao

Publications and source records attributed to Y Kitao.

At least 19 recordsLinked to original sources

PubMed2001

Regulation of tumor angiogenesis by oxygen-regulated protein 150, an inducible endoplasmic reticulum chaperone.

Expression of angiogenic factors such as vascular endothelial growth factor (VEGF) under conditions of cell stress involves both transcriptional and translational events, as well as an important role for inducible endoplasmic reticulum (ER) chaperones. Coexpression of VEGF and 150-kDa oxygen-regulated protein (ORP), a novel ER chaperone, in human glioblastoma suggested a link between angiogenesis and ORP150. C6 glioma cells stably transfected with ORP150 antisense displayed selectively reduced ORP150 expression. Tumors raised after inoculation of immunocompromised mice with ORP150 antisense C6 glioma transfectants demonstrated an initial phase of growth comparable to wild-type C6 glioma cells which was followed by marked regression within 8 days. Decreased density of platelet/endothelial cell adhesion molecule 1-positive structures within the tumor bed was consistent with reduced angiogenesis in C6 gliomas expressing ORP150 antisense, compared with tumors derived from C6 cells overexpressing ORP150 sense or vector controls. In vitro, inhibition of ORP150 expression decreased release of VEGF into culture supernatants; in ORP150 antisense transfectants, VEGF accumulated intracellularly within the ER. These findings demonstrate a critical role for the inducible ER chaperone ORP150 in tumor-mediated angiogenesis via processing of VEGF, and, thus, highlight a new facet of angiogenic mechanisms amenable to therapeutic manipulation in tumors.

Animals↗

PubMed2001

An exact test for the association between the disease and alleles at highly polymorphic loci with particular interest in the haplotype analysis.

The association analysis between the disease and genetic alleles is one of the simple methods for localizing the susceptibility locus in the genes. For revealing the association, several statistical tests have been proposed without discussing explicitly the alternative hypotheses. We therefore specify two types of alternative hypotheses (i.e., there is only one susceptibility allele in the locus, and there is an extension or shortening of alleles associated with the disease) and derive exact tests for the respective hypotheses. We also propose to combine these two tests when the prior knowledge is not sufficient enough to specify one of these two hypotheses. In particular, these ideas are extended to the haplotype analysis of three-way association between the disease and bivariate allele frequencies at two closely linked loci. As a by-product, a factorization of the probability distribution of the three-way cell frequencies under the null hypothesis of no three-way interaction is obtained.

Algorithms↗

PubMed2001

Expression of the oxygen-regulated protein ORP150 accelerates wound healing by modulating intracellular VEGF transport.

Expression of angiogenic factors such as VEGF under conditions of hypoxia or other kinds of cell stress contributes to neovascularization during wound healing. The inducible endoplasmic reticulum chaperone oxygen-regulated protein 150 (ORP150) is expressed in human wounds along with VEGF. Colocalization of these two molecules was observed in macrophages in the neovasculature, suggesting a role of ORP150 in the promotion of angiogenesis. Local administration of ORP150 sense adenovirus to wounds of diabetic mice, a treatment that efficiently targeted this gene product to the macrophages of wound beds, increased VEGF antigen in wounds and accelerated repair and neovascularization. In cultured human macrophages, inhibition of ORP150 expression caused retention of VEGF antigen within the endoplasmic reticulum (ER), while overexpression of ORP150 promoted the secretion of VEGF into hypoxic culture supernatants. Taken together, these data suggest an important role for ORP150 in the setting of impaired wound repair and identify a key, inducible chaperone-like molecule in the ER. This novel facet of the angiogenic response may be amenable to therapeutic manipulation.

Adenoviridae↗

PubMed2001

Expression of the endoplasmic reticulum molecular chaperone (ORP150) rescues hippocampal neurons from glutamate toxicity.

A series of events initiated by glutamate-receptor interaction perturbs cellular homeostasis resulting in elevation of intracellular free calcium and cell death. Cells subject to such environmental change express stress proteins, which contribute importantly to maintenance of metabolic homeostasis and viability. We show that an inducible chaperone present in endoplasmic reticulum (ER), the 150-kDa oxygen-regulated protein (ORP150), is expressed both in the human brain after seizure attack and in mouse hippocampus after kainate administration. Using mice heterozygous for ORP150 deficiency, exposure to excitatory stimuli caused hippocampal neurons to display exaggerated elevation of cytosolic calcium accompanied by activation of mu-calpain and cathepsin B, as well as increased vulnerability to glutamate-induced cell death in vitro and decreased survival to kainate in vivo. In contrast, targeted neuronal overexpression of ORP150 suppressed each of these events and enhanced neuronal and animal survival in parallel with diminished seizure intensity. Studies using cultured hippocampal neurons showed that ORP150 regulates cytosolic free calcium and activation of proteolytic pathways causing cell death in neurons subject to excitatory stress. Our data underscore a possible role for ER stress in glutamate toxicity and pinpoint a key ER chaperone, ORP150, which contributes to the stress response critical for neuronal survival.

Animals↗

PubMed2000

4-Aminoquinolines: novel nociceptin antagonists with analgesic activity.

Small-molecule nociceptin antagonists were synthesized to examine their therapeutic potential. After a 4-aminoquinoline derivative was found to bind with the human ORL(1) receptor, a series of 4-aminoquinolines and related compounds were synthesized and their binding was evaluated. Elucidation of structure-activity relationships eventually led to the optimum compounds. One of these compounds, N-(4-amino-2-methylquinolin-6-yl)-2-(4-ethylphenoxymethyl)benzamide hydrochloride (11) not only antagonized nociceptin-induced allodynia in mice but also showed analgesic effect in a hot plate test using mice and in a formalin test using rats. Its analgesic effect was not antagonized by the opioid antagonist naloxone. These results indicate that this nociceptin antagonist has the potential to become a novel type of analgesic that differs from mu-opioid agonists.

Adenosine Monophosphate↗

PubMed2000

A contribution to genome-wide association studies: search for susceptibility loci for schizophrenia using DNA microsatellite markers on chromosomes 19, 20, 21 and 22.

As an initial step for genome-wide association studies, we sought an association between schizophrenia and 34 microsatellite markers on chromosomes 19, 20, 21 and 22 by a case-control design. The samples examined for an association were 168 schizophrenic patients and 146 control subjects in the Japanese population. The allele distribution of the 34 loci differed significantly between Japanese and French populations. Significant deviation from the Hardy-Weinberg equilibrium was observed at D19S209 and D21S1256 in the control subjects. Case-control comparisons of the initial screening revealed a significant difference in allele frequency at D20S95 and a trend of difference at D20S118. To confirm these possible associations, additional samples consisting of 110 schizophrenic patients and 116 control subjects were examined, and an association between D20S95 and schizophrenia was confirmed (corrected P value after Bonferroni correction, 0.00035). D20S95 is located close to the gene (CHGB) encoding chromogranin B. These findings suggest that CHGB could be an important candidate gene involved in the development of schizophrenia.

Case-Control Studies↗

PubMed1997

[A two-year asymptomatic case with postoperative lung metastasis of sigmoid colon cancer responding to sequential methotrexate and 5-fluorouracil].

In a 76-year-old female outpatient, recurrent lung metastasis after sigmoidectomy due to sigmoid colon cancer responded to chemotherapy of sequential methotrexate and 5-fluorouracil. A total of 46 courses of this chemotherapy in two years suppressed the rapid growth of the metastasis. During this therapy, the patient's condition was good, with no experience of nausea or leukopenia. This case suggests that chemotherapy of sequential methotrexate and 5-fluorouracil gave a person with lung metastasis of sigmoid colon cancer a good quality of life during a long time.

Adenocarcinoma↗

PubMed1996

Crossed projection neurons are generated prior to uncrossed projection neurons in the lateral superior olive of the rat.

The present study examined in the lateral superior olive (LSO) of the rat whether LSO neurons projecting to the ipsilateral inferior colliculus (IC) might be generated later than those projecting to the contralateral IC. Rat fetuses were exposed in utero to 5-bromodeoxyuridine (BrdU), a thymidine analogue, to label neurons proliferating at different embryonic stages from day E11 through to E20. Upon reaching adulthood, the rats were given unilateral injections of fluoro-gold (FG), a retrograde fluorescent tracer, into the IC. Subsequently, the tissue sections of the brains obtained from the rats were immunostained for BrdU to simultaneously detect neurons that were BrdU-positive and/or FG-positive. BrdU-positive LSO neurons were found in the rats which had been exposed to BrdU during E12-E16. In E12 and E13 BrdU-exposure cases, the vast majority of doubled-labeled (BrdU-positive and FG-positive) neurons were seen on the contralateral side to the FG injection. In E14, E15 and E16 BrdU-exposure cases, in contrast, all double-labeled neurons were found on the ipsilateral side to the FG injection. The distribution of these double-labeled neurons within the nucleus was diffuse in all the BrdU-exposure cases. Thus, the results indicate that LSO neurons are generated during E12-E16, that the crossed projection neurons are generated 1-4 days earlier than the uncrossed projection neurons, and that no topographical relationships exist between the early- and the late-generated populations of the LSO neurons.

Animals↗

PubMed1996

Dopamine transporter gene polymorphism and psychiatric symptoms seen in schizophrenic patients at their first episode.

To investigate the possible role of the dopamine transporter (DAT) gene in determining the phenotype in human subjects, allele frequencies for the 40-bp variable number of tandem repeats (VNTR) polymorphism at this site were compared between 117 Japanese normal controls and 118 schizophrenic patients, including six subgroups: early-onset, those with a family history, and those suffering from one of the following psychiatric symptoms at their first episode: delusion and hallucination; disorganization; bizarre behavior; and negative symptoms. No significant differences were observed between the group as a whole or any subgroup of schizophrenic patients and controls. The results indicate that VNTR polymorphism in the DAT gene is unlikely to be a major contributor to any of the psychiatric parameters examined in the present population of schizophrenic subjects.

Adult↗

PubMed1996

Neurogenesis of subpopulations of rat lumbar dorsal root ganglion neurons including neurons projecting to the dorsal column nuclei.

The time of birth of subpopulations of dorsal root ganglion (DRG) neurons was studied with immunohistochemistry for 5-bromodeoxyuridine (BrdU). Pregnant rats were injected with BrdU i.p. to label the neurons on one of the embryonic days (E) E11-E16. When they were adults, the rats were given injections of Fluoro-Gold (FG) into the gracile nucleus to identify DRG neurons projecting to this structure. Following a 5 day survival period, the animals were perfused with aldehyde fixative. Sections from the L3-L5 DRGs were processed for BrdU immunohistochemistry followed by either immunostaining for the antineurofilament antibody RT97, as marker of the light neuronal subpopulation, or histochemical staining for the B4 isolectin from Griffonia simplicifolia I, as marker of the small dark subpopulation. The results indicated that the DRG neurons were generated between E12 and E16. The RT97+ neurons were generated on E12-E15, with a peak at E13. FG+ neurons, the majority of which were RT97+, were also generated on E12-E15. The B4+ neurons were generated on E13-E16, with a peak around E14. The overall pattern of neurogenesis of the DRG neurons showed that the RT97+ neurons were produced prior to the B4+ neurons. These findings are in agreement with earlier observations that the large DRG neurons are generated earlier than the small dark neurons. Our findings also suggest the existence of a third neuronal subpopulation that might be produced at the latest period of DRG neurogenesis at E15-E16.

Animals↗

PubMed1996

Inhibitory effects and toxicity of green tea polyphenols for gastrointestinal carcinogenesis.

BACKGROUND: Recently, and epidemiologic study showed a lower risk of gastrointestinal carcinogenesis in green tea drinkers. An experiment on two-stage skin carcinogenesis in mice showed that (-)-epigallocatechin gallate (EGCG), one of the main constituents of green tea, inhibited tumor formation. METHODS: The inhibitory effects of EGCG and green tea extract (GTE) on N-ethyl-N'-nitro-N-nitroguanidine (ENNG)-induced duodenal carcinogenesis in the mouse, N-methyl-N'-nitro-N-nitrosoguanidine (MNNG)-induced carcinogenesis of the glandular stomach in the rat, and azoxymethane-induced colon carcinogenesis in the rat were examined. The toxicity of GTE was assessed experimentally and GTE was applied clinically in normal volunteers to determine the effective dose and to assess its harmful effects. RESULTS: EGCG and GRE inhibited chemical carcinogenesis of the gastrointestinal tract in rodents. Judging from the epidemiologic and experimental findings, it was determined that 1 g per day of GTE might be an effective dose. GTE was not toxic and no harmful effect was found during its clinical use. CONCLUSIONS: These findings suggest that EGCG and GTE are useful in preventing gastrointestinal carcinogenesis, and the clinical usefulness of GTE, which has no harmful effects and is inexpensive, should be studied further.

Animals↗

PubMed1996

Determination of absolute configuration and biological activity of new immunosuppressants, mycestericins D, E, F and G.

Mycestericins D, E, F and G were isolated from the culture broth of Mycelia sterilia ATCC 20349 as potent immunosuppressants. Mycestericins F and G were identical with dihydromycestericins D and E, respectively. Their absolute configurations were determined by use of the modified MOSHER'S method and by comparison of the CD spectra of their benzoate derivatives with those of synthetic analogs. Mycestericins D, E, F and G suppressed the proliferation of lymphocytes in the mouse allogeneic mixed lymphocyte reaction.

Animals↗

PubMed1995

Inhibition of N-methyl-N'-nitro-N-nitrosoguanidine-induced carcinogenesis by (-)-epigallocatechin gallate in the rat glandular stomach.

Recently, an epidemiological study showed a lower risk of gastric cancer among people who consume a large amount of green tea. (-)-Epigallocatechin gallate (EGCG), one of the main constituents of green tea, inhibited tumor promotion by teleocidin in a two-stage carcinogenesis experiment with the use of mouse skin. The inhibitory effect of EGCG on N-methyl-N'-nitro-N-nitrosoguanidine (MNNG)-induced carcinogenesis of the glandular stomach in rats was examined. The percentage of tumor-bearing rats in the group treated with MNNG plus EGCG was 31%, compared to 62% in the MNNG group. The difference was statistically significant (P < 0.05). To assess the effect of p.o. administration of EGCG, the gastric mucosal cellular kinetics was examined with the use of the bromodeoxyuridine labeling index, ornithine decarboxylase activity, and tissue polyamine levels. The labeling index of the EGCG treatment group decreased significantly (P < 0.05) compared to the EGCG plus MNNG treatment group. The ornithine decarboxylase activity and tissue spermidine levels were also decreased. On the other hand, the tissue putrescine and spermine levels were partly increased. These findings suggest that EGCG inhibits the cellular kinetics of the gastric mucosa during the promotion stage of MNNG-induced gastric carcinogenesis. EGCG may be useful in preventing gastric carcinogenesis. Moreover, EGCG may be applied clinically without any harmful effects and at a low cost.

Adenocarcinoma↗

PubMed1995

Immunohistochemical staining and activity of ornithine decarboxylase in colorectal cancer.

Using a new anti-human ornithine decarboxylase (anti-hODC) monoclonal antibody, the relationship between the immunoreactivity of ODC and its activity was analyzed in 21 human colorectal cancer tissues, 42 adjacent non-tumorous mucosa specimens, and 10 normal rectal mucosa samples from frozen sections and paraffin-embedded samples. A statistical significant correlation was found between the antibody reaction and the enzymic activity (P < 0.01). The immunohistochemical staining for ODC provides a new and simplified procedure for studying the activity of ODC as compared to previous methods using radioisotopes. It offers the advantages of retrospectively determining the amount of ODC in samples previously embedded in paraffin.

Aged↗

PubMed1995

Electron microscopic study of synaptogenesis and myelination of the olfactory centers in developing rats.

Development of the central olfactory system was studied in the rat with an electron microscope at three main structures: the olfactory bulb, the lateral olfactory tract, and the primary olfactory cortex (the piriform cortex). As a parameter of development, the synaptic density was examined quantitatively in the bulbar glomerulus and layer Ia (termination of bulbofugal fibers) of the piriform cortex. which are the key stations of the olfactory pathway. The synaptic densities in the glomerulus and those in layer Ia were 5.7% and 4.6% on embryonic day 19, 15.8% and 12.5% on postnatal day (P) 0, and 57.3% and 37.2% on P10, as compared with the adult (100%). As another parameter of development, the density of myelinated axons in the lateral olfactory tract was examined quantitatively. The densities of myelinated axons in the tract were 0% on P5, 15.1% on P10, and 73.5% on P21 of the adult density. Maturation in the tract was still progressing, even at P21, in terms of bundle formation and the thickness of myelin sheaths. The results show that synaptogenesis in the bulbar glomerulus is followed by synaptogenesis in layer Ia of the piriform cortex, and that myelination in the lateral olfactory tract occurs over a prolonged period, even in the stages after P21.

Aging↗

PubMed1995

Rolipram, a selective c-AMP phosphodiesterase inhibitor suppresses oro-facial dyskinetic movements in rats.

Since striatal dopamine D2 receptor supersensitivity in the etiology of tardive dyskinesia has been suggested and dopamine D2 receptors are known to inhibit adenylate cyclase activity resulting in a decrease of cyclic adenosine 3',5'-monophosphate (cAMP) levels, we hypothesized that an increase in cAMP levels ameliorates the condition. In the present study, 21-day haloperidol treatment (1.5 mg/kg I.P.) in rats resulted in an increase in striatal [3H]-spiperone (D2) binding whereas [3H] SCH23390 (D1) binding was unaltered. This haloperidol treatment also induced a significantly increase in the frequency of involuntary chewing movements and tongue protrusions, which are considered as a model of tardive dyskinesia. These dyskinetic movements were suppressed by administration of rolipram (0.5 and 1.0 mg/kg I.P.), an inhibitor of the cAMP phosphodiesterase type IV. The present results suggest that selective cAMP phosphodiesterase type IV inhibitors could be putative therapeutic drugs for tardive dyskinesia.

3',5'-Cyclic-AMP Phosphodiesterases↗

PubMed1995

Postnatal development of the projection from the medial superior olive to the inferior colliculus in the rat.

Normal projection development from the medial superior olive (MSO) to the inferior colliculus (IC) was examined by injecting Fluoro-Gold (FG), a retrograde tracer, into the IC unilaterally at postnatal days 0 (P0), P3, P7 and maturity. The rats were killed 1 day after FG injection. At all ages, labeled neurons in the MSO appeared on the ipsilateral side only, as in adult controls. The total number of MSO neurons counted in Nissl-stained sections was constant throughout the postnatal periods. The labeled frequency index of MSO neurons was increased stepwise (from 35% to 90%) with increasing postnatal stages (from P0 to adulthood), suggesting differential growth of early- and late-developing axons.

Age Factors↗

PubMed1995

Anatomical plasticity in the medial superior olive following ablation of the inferior colliculus in neonatal and adult rats.

We evaluated the consequences of unilateral ablation of the inferior colliculus (IC) upon the ascending projection from the medial superior olive (MSO) to the IC. Ablation of the IC was performed in rats aged between postnatal day 1 (P1) and maturity. All the rats were given injections of Fluoro-Gold (FG) into the ipsilateral IC at birth (P0) (before the ipsilateral IC was ablated in any case) so that growth of early-developing axons to the ipsilateral IC could be examined for any labeled neurons in the ipsilateral MSO. Upon reaching adulthood, the rats received injections of Fluoro-Ruby (FR) into the contralateral (intact) IC so that aberrant crossed projections to the intact IC could be examined for any labeled neurons in the ipsilateral MSO. These rats were killed 2 days after FR injections. The number of surviving cells in the ipsilateral MSO were counted in Nissl-stained sections for quantitative analysis of retrograde degeneration. The results show that: (1) the total number of neurons was reduced to 64-34% in the ipsilateral MSO as a result of IC ablation; (2) cell reduction by retrograde degeneration followed a U-shaped curve with a maximal effect in rats operated at P7 (reduced to 34%); (3) adult ablation of the IC led to retrograde degeneration that was less severe than that in late neonatal (P7) ablation; (4) an aberrant projection from the MSO to the contralateral IC occurred in rats operated at P1 and P3 but not in rats operated at P7 or maturity. Thus, our findings suggest that growth of late-developing axons is a major factor in the plasticity of this system of projection.

Age Factors↗