Biomedical subjects

T Saito

Publications and source records attributed to T Saito.

At least 199 records · Page 11Linked to original sources

PubMed2001

Increased levels of calcium-sensitive adenylyl cyclase subtypes in the limbic system of alcoholics: evidence for a specific role of cAMP signaling in the human addictive brain.

We examined the amounts of several adenylyl cyclase (AC) isoforms and of cAMP-response element binding protein (CREB) in alcoholic and control brains. Immunoreactivity of type I AC was significantly increased in alcoholic nucleus accumbens and corpus amygdaloideum. Immunoreactivity of type VIII AC was also increased in alcoholic corpus amygdaloideum and hippocampus. CREB immunoreactivities were unchanged. These findings indicate that the brain-region specific increase of Ca(2+)-sensitive AC may contribute to the pathophysiology of alcoholism.

Adenylyl Cyclases↗

PubMed2001

Expression of multidrug resistance protein 1 (MRP1) in the rat cochlea with special reference to the blood-inner ear barrier.

Expression of multidrug resistance protein 1 (MRP1) was detected in the rat cochlea by RT-PCR and immunohistochemistry using anti-MRP monoclonal antibody MRPr1. Use of primers specific for rat mrp1 gene resulted in the amplification of an expected 394 bp fragment prepared from brain and cochlear tissues. Immunohistochemically, MRP was found in the choroid plexus, stria vascularis, spiral ligament, spiral prominence and cochlear nerve in the modiolus. From these results, it was suggested that MRP in the rat cochlea might function as an extrusion pump and play an important role in the blood-inner ear barrier.

ATP Binding Cassette Transporter, Subfamily B↗

PubMed2001

Measurement of the B(e2) of (7)(lambda)Li and shrinkage of the hypernuclear size.

We report on the first measurement of a hypernuclear gamma-transition probability. gamma rays emitted in the E2(5/2(+)-->1/2(+)) transition of (7)(Lambda)Li were detected by a large-acceptance germanium detector array (Hyperball), and the lifetime of the parent state ( 5/2(+)) was determined by the Doppler shift attenuation method. The obtained result, 5.8(+0.9)(-0.7)+/-0.7 ps, was then converted into the reduced transition probability [ B(E2)] to be B(E2;5/2(+)-->1/2(+)) = 3.6+/-0.5(+0.5)(-0.4) e(2) fm(4). Compared with the B(E2) of the corresponding E2(3(+)-->1(+)) transition in the 6Li nucleus, our result gives evidence that the size of the 6Li core in (7)(Lambda)Li is smaller than the 6Li nucleus in the free space.

Journal Article↗

PubMed2001

Wave packet dynamics in a quasi-one-dimensional metal-halogen complex studied by ultrafast time-resolved spectroscopy.

An ultrafast optical response is studied in a quasi-one-dimensional halogen-bridged mixed-valence metal complex [Pt(en)(2)] [Pt(en)2I2] (ClO4)(4) with ultrafast time resolution. Wave packet motions both in the ground and self-trapped exciton (STE) states are observed as oscillatory modulations in the time-resolved reflectivity. The wave packet motion on the STE potential surface begins after about 50 fs with respect to the photoexcitation. This delay is attributed to the lattice relaxation from the free exciton state to the STE state.

Journal Article↗

PubMed2001

Experimental transmission of sheep-associated malignant catarrhal fever from sheep to Japanese deer (Cervus nippon) and cattle.

The assumption that sheep carry ovine herpesvirus-2 (OvHV-2), the causative agent of sheep-associated malignant catarrhal fever (SA-MCF), is widely accepted, albeit OvHV-2 has not been isolated. We attempted experimental contact transmission of MCF from Japanese sheep persistently infected with OvHV-2 to Japanese deer (Cervus nippon) and cattle. In Experiment 1, a deer was kept in close quarters with an infected ewe. In Experiment 2, a second deer was kept with the same ewe. In Experiment 3, two cows were each kept with two infected wethers. In Experiment 1, the deer developed clinical signs at 138 days after first contact and then died. OvHV-2 genes by polymerase chain reaction (PCR) and fluorescent antibodies to Alcelaphine herpesvirus-1 were detected in the affected deer. Moreover, sequences of PCR products (423bp), obtained by amplification of materials from the sheep and from the affected deer, coincided. These results clearly confirmed that the sheep was a carrier of OvHV-2, and that this virus had induced SA-MCF in a deer. In other experiments, no OvHV-2 infection occurred in deer and cattle during the 6-18 months periods of contact, though viral genes were detected in the nasal swabs and white blood cells of the sheep. To our knowledge, this is the first report on successful experimental transmission of MCF from OvHV-2-infected sheep to deer.

Animals↗

PubMed2001

In situ XAFS analysis system for high-pressure catalytic reactions and its application to CO2 hydrogenation over a Rh/Y-zeolite catalyst.

An in-situ XAFS cell was developed and used for the structural analysis of a Rh ion-exchanged zeolite catalyst during high-pressure hydrogenation of carbon dioxide. The in-situ cell enabled analyses of the catalyst structures that changed with the reaction atmosphere and elapsed time; the peak assigned to Rh-O scattering changed to that assigned to Rh-Rh scattering at 404 K during the pretreatment by hydrogen. After 30 min. of the carbon dioxide hydrogenation reaction, the peak intensity assigned to Rh-Rh scattering increased corresponding to the increase in the catalytic activity.

Journal Article↗

PubMed2001

Arginine vasopressin inhibits apoptosis of rat glomerular mesangial cells via V1a receptors.

Arginine vasopressin (AVP) promotes proliferation of glomerular mesangial cells. We examined whether AVP modulates an apoptosis of cultured rat glomerular mesangial cells at 3-17th passages. The agarose gel electrophoresis demonstrated that AVP attenuated a ladder formation stimulated by the serum deprivation. The quantitation of oligonucleosomes by ELISA also showed that AVP suppressed the serum deprivation-induced apoptosis. Such an antiapoptotic effect of AVP was dose-dependent. An AVP V1a receptor antagonist, d(CH2)5Tyr(Me)AVP, abolished the antiapoptotic effect of AVP. The inhibitory effect of AVP on the apoptosis was reduced by staurosporine and mimicked by phorbol-12-myristate-13-acetate. These results suggest that AVP inhibits serum deprivation-induced apoptosis of glomerular mesangial cells via V1a receptor-protein kinase C pathway.

Animals↗

PubMed2001

cDNA cloning and expression of swine IL-7 from neonatal intestinal epithelium.

Swine IL-7 (sIL-7) cDNA has been isolated from neonatal intestinal epithelium by reverse transcription polymerase chain reaction (RT-PCR) with designated primers based on the conserved sequences of the other mammalian IL-7. Recombinant sIL-7 was able to induce the bone marrow cell proliferation like human IL-7. The complete open reading frame contains 531 bp coding deduced 176 amino acid residues, with a calculated molecular mass of 20.1 kDa. The observed similarity between swine and human IL-7 sequences (66% identical and 89% conserved) suggests that a study on the immune responses correlated with IL-7 in the gut of swine will be valuable to understand their mechanisms in human. By RT-PCR using the constructed specific primers to sIL-7, sIL-7 mRNA was confirmed to be expressed in swine intestine, thymus, kidney and skin but not in the heart.

Amino Acid Sequence↗

PubMed2001

Occurrence of an unusual phosphorylated N-acetyllactosamine in horse colostrum.

The colostrum of horses (thoroughbreds) was extracted and fractionated to yield Gal(beta1-4)GlcNAcalpha1-phosphate, which has not previously been detected in any mammalian milk or colostrum, as well as Neu5Ac(alpha2-3)Gal(beta1-4)Glc. The structures of these saccharides were established by NMR spectroscopy and MALDI-TOF mass spectrometry.

Amino Sugars↗

PubMed2001

Over-expression of heat shock proteins in carcinogenic endometrium.

We have previously shown that the subcellular localization of beta-catenin changes according to the cell proliferation status of the human endometrium, suggesting a role of intercellular transduction in cell growth control in human endometrium not only in the physiological but also in the carcinogenic condition. To further study the possible role of heat shock proteins (HSPs) in growth control, we immunohistochemically analyzed 92 endometrial samples, 30 of normal endometrium, 20 of endometrial hyperplasia and 42 of endometrial cancer, for expression of HSP27, HSP70, HSP90, estrogen receptor (ER) and progesterone receptor. HSP27 and HSP90 were detected in endometrial epithelium strongly in the proliferative phase and weakly in the secretory phase during the menstrual cycle according to the serum estradiol level. However, they were over-expressed in endometrial hyperplasia, especially HSP27. In endometrial cancer, HSP27 expression was heterogenic among the glands and lower than that in the proliferative phase and endometrial hyperplasia. HSP27 over-expression was also observed in samples including endometrial cancer and associated hyperplasia. Results of Western blotting followed those of immunohistochemistry. HSP70 was not changed during the menstrual cycle, as HSP27 and HSP90 were, and was rather stably expressed in endometrial hyperplasia and cancer. Our results suggest that HSP27 and HSP90 contribute to cell proliferation in endometrial epithelium and that over-expression of HSP27 in endometrial hyperplasia occurs as a result of the activated condition of ER, though in cancer it decreases according to the loss of function of ER.

Adenocarcinoma↗

PubMed2001

Inhibition of tumor metastasis by adoptive transfer of IL-12-activated Valpha14 NKT cells.

A unique lymphocyte lineage, the Valpha14 NKT cells, expresses both NK1.1 and an invariant antigen receptor encoded by Valpha14 and Jalpha281 gene segments. Valpha14 NKT cells play crucial roles in various immune responses, including autoimmune diseases, allergic reactions and anti-tumor immunity. Valpha14 NKT cells were demonstrated to be essential for anti-tumor effect of IL-12 in vivo. Here, we report that adoptive transfer of IL-12-activated Valpha14 NKT cells prevents hepatic metastasis of B16 melanoma. The injection of large amounts of IL-2, IL-4, and IFN-gamma, which are cytokines produced by activated Valpha14 NKT cells, exhibited no significant inhibition of the metastasis of this melanoma. The cells prepared from the liver of IL-12-injected mice expressed a potent cytotoxic activity on B16 melanoma cells in vitro. Although the adoptive transfer of IL-12-activated Valpha14 NKT cells prevents hepatic metastasis of B16 melanoma, activated NK cells from IL-12-injected RAG-1-/- mice failed to inhibit the metastasis of this melanoma. Thus, the anti-tumor effect of IL-12 can be replaced by adoptive transfer of IL-12-activated Valpha14 NKT cells but not by IL-12-activated NK cells, suggesting a minor role of NK cells for the IL-12-mediated anti-tumor effect in this experimental system. Moreover, our studies have suggested the involvement of direct cytotoxic mechanisms rather than cytokine-mediated immune responses at the effector phase of the Valpha14 NKT cell-mediated anti-tumor activity.

Adoptive Transfer↗

PubMed2001

Domain-specific mutations of a transforming growth factor (TGF)-beta 1 latency-associated peptide cause Camurati-Engelmann disease because of the formation of a constitutively active form of TGF-beta 1.

Transforming growth factor (TGF)-beta1 is secreted as a latent form, which consists of its mature form and a latency-associated peptide (beta1-LAP) in either the presence or the absence of additional latent TGF-beta1-binding protein. We recently reported that three different missense mutations (R218H, R218C, and C225R) of beta1-LAP cause the Camurati-Engelmann disease (CED), an autosomal dominant disorder characterized by hyperosteosis and sclerosis of the diaphysis of the long bones. Pulse-chase experiments using fibroblasts from CED patients and expression experiments of the mutant genes in an insect cell system suggest that these mutations disrupt the association of beta1-LAP and TGF-beta1 and the subsequent release of the mature TGF-beta1. Furthermore, the cell growth of fibroblasts from a CED patient and mutant gene-transfected fibroblasts was suppressed via TGF-beta1. The growth suppression observed was attenuated by neutralizing antibody to TGF-beta1 or by treatment of dexamethasone. On the other hand, the proliferation of human osteoblastic MG-63 cells was accelerated by coculture with CED fibroblasts. These data suggest that the domain-specific mutations of beta1-LAP result in a more facile activation of TGF-beta1, thus causing CED.

Camurati-Engelmann Syndrome↗

PubMed2001

Functional annotation of a full-length mouse cDNA collection.

The RIKEN Mouse Gene Encyclopaedia Project, a systematic approach to determining the full coding potential of the mouse genome, involves collection and sequencing of full-length complementary DNAs and physical mapping of the corresponding genes to the mouse genome. We organized an international functional annotation meeting (FANTOM) to annotate the first 21,076 cDNAs to be analysed in this project. Here we describe the first RIKEN clone collection, which is one of the largest described for any organism. Analysis of these cDNAs extends known gene families and identifies new ones.

Animals↗

PubMed2001

Phosphorylation of protein phosphatase inhibitor-1 by Cdk5.

Protein phosphatase inhibitor-1 is a prototypical mediator of cross-talk between protein kinases and protein phosphatases. Activation of cAMP-dependent protein kinase results in phosphorylation of inhibitor-1 at Thr-35, converting it into a potent inhibitor of protein phosphatase-1. Here we report that inhibitor-1 is phosphorylated in vitro at Ser-67 by the proline-directed kinases, Cdk1, Cdk5, and mitogen-activated protein kinase. By using phosphorylation state-specific antibodies and selective protein kinase inhibitors, Cdk5 was found to be the only kinase that phosphorylates inhibitor-1 at Ser-67 in intact striatal brain tissue. In vitro and in vivo studies indicated that phospho-Ser-67 inhibitor-1 was dephosphorylated by protein phosphatases-2A and -2B. The state of phosphorylation of inhibitor-1 at Ser-67 was dynamically regulated in striatal tissue by glutamate-dependent regulation of N-methyl-d-aspartic acid-type channels. Phosphorylation of Ser-67 did not convert inhibitor-1 into an inhibitor of protein phosphatase-1. However, inhibitor-1 phosphorylated at Ser-67 was a less efficient substrate for cAMP-dependent protein kinase. These results demonstrate regulation of a Cdk5-dependent phosphorylation site in inhibitor-1 and suggest a role for this site in modulating the amplitude of signal transduction events that involve cAMP-dependent protein kinase activation.

Animals↗

PubMed2001

Immunohistochemical distribution of the receptor for advanced glycation end products in neurons and astrocytes in Alzheimer's disease.

Advanced glycation end products (AGE) and the receptor for AGE (RAGE) have been implicated in the chronic complications of diabetes mellitus (DM), and have been reported to play an important role in the pathogenesis of Alzheimer's disease (AD). In this study, we established a polyclonal anti-RAGE antibody, and examined the immunohistochemical localization of amyloid beta protein (Abeta), AGE, and RAGE in neurons and astrocytes from patients with AD and DM. Our anti-RAGE antibody recognized full-length RAGE (50 kd) and N-terminal RAGE (35 kd) in human brain tissue. Abeta-, AGE-, and RAGE-positive granules were identified in the perikaryon of hippocampal neurons (especially from CA3 and CA4) in all subjects. The distribution and staining pattern of these immunopositive granules showed good concordance with each antibody. In AD, most astrocytes contained both AGE-and RAGE-positive granules and their distribution was almost the same. Abeta-positive granules were less common, but Abeta-, AGE-, and RAGE-positive granules were colocalized in one part of a single astrocyte. In DM patients and control cases, AGE-and RAGE-positive astrocytes were very rare. These finding support the hypothesis that glycated Abeta is taken up via RAGE and is degraded through the lysosomal pathway in astrocytes. In addition to the presence of AGE, the process of AGE degradation and receptor-mediated reactions may contribute to neuronal dysfunction and promote the progression of AD.

Aged↗

PubMed2001

Signal-binding specificity of the mu4 subunit of the adaptor protein complex AP-4.

The medium (mu) chains of the adaptor protein (AP) complexes AP-1, AP-2, and AP-3 recognize distinct subsets of tyrosine-based (YXXphi) sorting signals found within the cytoplasmic domains of integral membrane proteins. Here, we describe the signal-binding specificity and affinity of the medium subunit mu4 of the recently described adaptor protein complex AP-4. To elucidate the determinants of specificity, we screened a two-hybrid combinatorial peptide library using mu4 as a selector protein. Statistical analyses of the results revealed that mu4 prefers aspartic acid at position Y+1, proline or arginine at Y+2, and phenylalanine at Y-1 and Y+3 (phi). In addition, we examined the interaction of mu4 with naturally occurring YXXphi signals by both two-hybrid and in vitro binding analyses. These experiments showed that mu4 recognized the tyrosine signal from the human lysosomal protein LAMP-2, HTGYEQF. Using surface plasmon resonance measurements, we determined the apparent dissociation constant for the mu4-YXXphi interaction to be in the micromolar range. To gain insight into a possible role of AP-4 in intracellular trafficking, we constructed a Tac chimera bearing a mu4-specific YXXphi signal. This chimera was targeted to the endosomal-lysosomal system without being internalized from the plasma membrane.

Adaptor Proteins, Vesicular Transport↗

PubMed2001

Negative regulation of expression and function of Fc gamma RIII by CD3 zeta in murine NK cells.

Fc gamma RIII is involved in Ab-dependent cell-mediated cytotoxicity (ADCC) and cytokine production by NK cells. Signaling and expression of Fc gamma RIII are dependent on FcR gamma. Although NK cells express not only FcR gamma but also CD3 zeta, the role of CD3 zeta in NK cell function remains unclear. Here, we found that the expression of Fc gamma RIII on NK cells from CD3 zeta-deficient mice is unexpectedly up-regulated compared with that on cells from normal mice. Furthermore, ADCC and IFN-gamma production upon Fc gamma RIII-cross-linking by NK cells from CD3 zeta-deficient mice were also up-regulated. Up-regulation of the surface expression of Fc gamma RIII on CD3 zeta-deficient NK cells is not mediated by transcriptional augmentation of either Fc gamma RIII or FcR gamma gene because there was no significant difference in the expression of mRNA for Fc gamma RIII and FcR gamma. Transfection of CD3 zeta into a cell line expressing Fc gamma RIII and FcR gamma induced a decrease in the cell surface expression of Fc gamma RIII. These findings reveal a negative regulatory role of CD3 zeta in Fc gamma RIII-mediated function of murine NK cells.

3T3 Cells↗

PubMed2001

Serum levels of fluconazole in patients after cytotoxic chemotherapy for hematological malignancy.

We performed a prospective evaluation of pharmacokinetics of fluconazole administered for prophylactic purposes to 19 patients after cytotoxic chemotherapy for hematological malignancies. On days 7 and 15, we obtained 5 ml of blood from each patient. If fluconazole was administered orally, blood samples were drawn 2, 8, and 24 hr after ingestion of the drug. If it was administered intravenously, blood samples were drawn 1, 8, and 24 hr post-injection. Serum fluconazole levels were analyzed by HPLC with ultraviolet light detection. In patients receiving 200 or 400 mg of fluconazole per day, maximal serum levels were 7.9 and 15.6 mg/l and minimum levels were 5.0 and 10.3 mg/l, respectively. There was no significant difference in serum fluconazole levels comparing the levels after oral and intravenous administration, and pharmacokinetic parameters of fluconazole were comparable at each time point within one dose level. However, considerable variation in serum fluconazole levels was noted in this study, as the maximal serum levels ranged from 4.0 to 13.3 mg/l and from 8.7 to 26.9 mg/l in patients receiving 200 and 400 mg of fluconazole orally, respectively. These variations may be associated with prophylactic failures for patients with insufficient fluconazole concentrations. Multiple regression analysis showed significant correlation between serum fluconazole levels and some variables including dose of fluconazole, age, serum aspartate aminotransferase levels and blood urea nitrogen levels. These variations may be associated with disturbance of body water balance, such as massive hemorrhage and dehydration.

Adult↗