Biomedical subjects

T Yamada

Publications and source records attributed to T Yamada.

At least 343 records · Page 19Linked to original sources

PubMed2000

Mycobacterium bovis bacillus calmette-guérin induces protective immunity against infection by Plasmodium yoelii at blood-stage depending on shifting immunity toward Th1 type and inducing protective IgG2a after the parasite infection.

Bacillus calmette-guérin (BCG)-vaccination raised dramatically the survival rates of A/J mice from infection by Plasmodium yoelii 17XL at blood-stage. The analysis of the immune response of spleen cells indicated that BCG vaccination biased the immune response toward Th1 type. Neutralization of IFN-gamma and nitric oxide abrogated the protection. The kinetics of Ab production in the course of P. yoelii 17XL infection was monitored. Surprisingly, larger amounts of parasite-specific Abs were produced in BCG-vaccinated mice than in the placebo control. The vast majority of the produced IgG against parasites in BCG-vaccinated mice was IgG2a, which was observed hardly in placebo controls. The peak of IgG2a production coincided with the clearance of infection. The naive mice transferred adoptively with IgG2a from self-cured mice survived the lethal challenge from the parasite. These data indicated that BCG vaccination protected A/J mouse from P. yoelii 17XL infection by biasing immunity toward Th1-type after parasite infection and enhancing production of IgG2a, which ultimately played a major role in protection.

Animals↗

PubMed2000

3-phosphoinositide-dependent protein kinase 1, an Akt1 kinase, is involved in dephosphorylation of Thr-308 of Akt1 in Chinese hamster ovary cells.

To investigate the role of 3-phosphoinositide-dependent protein kinase 1 (PDK1) in the Akt1 phosphorylation state, wild-type (wt) PDK1 and its kinase dead (kd) mutant were expressed using an adenovirus gene transduction system in Chinese hamster ovary cells stably expressing insulin receptor. Immunoblotting using anti-phosphorylated Akt1 antibody revealed Thr-308 already to be maximally phosphorylated at 1 min but completely dephosphorylated at 5 min, with insulin stimulation, whereas insulin-induced Akt1 activation was maintained even after dephosphorylation of Thr-308. Overexpression of wt-PDK1 further increased insulin-stimulated phosphorylation of Thr-308, also followed by rapid dephosphorylation. The insulin-stimulated Akt1 activity was also enhanced by wt-PDK1 expression but was maintained even at 15 min. Thus, phosphorylation of Thr-308 is not essential for maintaining the Akt1 activity once it has been achieved. Interestingly, the insulin-stimulated phosphorylation state of Thr-308 was maintained even at 15 min in cells expressing kd-PDK1, suggesting that kd-PDK1 has a dominant negative effect on dephosphorylation of Thr-308 of Akt1. Calyculin A, an inhibitor of PP1 and PP2A, also prolonged the insulin-stimulated phosphorylation state of Thr-308. In addition, in vitro experiments revealed PP2A, but not PP1, to dephosphorylate completely Thr-308 of Akt1. These findings suggest that a novel pathway involving dephosphorylation of Akt1 at Thr-308 by a phosphatase, possibly PP2A, originally, identified as is regulated downstream from PDK1, an Akt1 kinase.

3-Phosphoinositide-Dependent Protein Kinases↗

PubMed2000

Concurrent detection of gene mutations and chromosome aberrations induced by five chemicals in a CHL/IU cell line incorporating a gpt shuttle vector.

We previously established a transgenic Chinese hamster CHL/IU cell line, designated as KN63, for concurrent analysis of gene mutations and chromosome aberrations. The KN63 cell line contains copies of a shuttle vector with the Escherichia coli gpt gene as a mutational target in its chromosome. To evaluate the sensitivity of the cell line to various types of mutagens, methyl methanesulfonate (MMS), N-ethyl-N-nitrosourea (ENU), mitomycin C (MMC), vincristine sulfate (VIN) and C.I. basic red 9 hydrochloride (CIB) were assayed. KN63 cells were treated with each test chemical and gene mutations were detected in the gpt gene of the shuttle vector rescued from the KN63 cell genome into an E. coli host. Chromosome aberrations were concurrently evaluated by conventional metaphase analysis. MMS, ENU and MMC induced both gene mutations and structural chromosome aberrations in KN63 cells, with more efficient induction of the latter. VIN, a well-known aneugen, produced only numerical changes to chromosomes, while CIB was negative for both types of alteration. KN63 cells were as sensitive to MMS, ENU, MMC and VIN as Chinese hamster cell lines such as CHL, CHO and V79 cells. The characteristics of test chemicals indicated by this system should be useful for understanding endpoints in chemical mutagenesis.

Animals↗

PubMed2000

Diabetes and tumor formation in transgenic mice expressing Reg I.

To examine the effect of overexpressed regenerating gene (Reg) I on pancreatic beta-cells, we generated transgenic mice expressing Reg I in islets (Reg-Tg mice). Three lines of Reg-Tg mice were established. In line-1 Reg-Tg mice, the expression level of Reg I mRNA in islets was 7 times higher than those in lines 2 and 3 of Reg-Tg mice, and line 1 mice developed diabetes by apoptosis of beta-cells, as well as various malignant tumors. In addition to the decrease in beta-cells, compensatory islet regeneration and proliferation of ductal epithelial cells were observed in line-1 Reg-Tg mice. Because Reg I protein was secreted primarily into pancreatic ducts from acinar cells, it may primarily stimulate the proliferation of ductal epithelial cells, and not beta-cells, and their differentiation into islets. Moreover, the tumor-promoting activity of Reg I protein should be considered for its possible clinical applications.

Animals↗

PubMed2000

Genetic evidence for obesity loci involved in the regulation of body fat distribution in obese type 2 diabetes rat, OLETF.

The Otsuka Long-Evans Tokushima Fatty (OLETF) rat is an animal model for obese type 2 diabetes in human. Obesity is essential for the onset of type 2 diabetes in this rat. Our present investigation was designed to identify quantitative trait loci (QTLs) contributing to obesity by performing a whole-genome search using 214 F(2) intercross progeny between OLETF and F344 rats. We have identified six QTLs responsible for adiposity indices of fat pads on rat chromosomes 2 (Obs1 for mesenteric fat), 4 (Obs2 for retroperitoneal fat), 8 (Obs3 for mesenteric fat), 9 (Obs4 for retroperitoneal fat), and 14 (Obs5 and Obs6 for retroperitoneal fat), demonstrating that the adiposity indices of individual fat pads were under the control of different genes. As expected, the OLETF allele corresponds to increased adiposity indices for all QTLs, except for Obs3, in which the F344 allele leads to an increase in the index.

Adipose Tissue↗

PubMed2000

Algal-lytic activities encoded by Chlorella virus CVK2.

Using a halo assay with E. coli lysates expressing Chlorella virus CVK2 genes on a cosmid contig, two different algal-lytic activities against Chlorella strain NC64A cells were found to be encoded on the CVK2 genome. The gene for vAL-1, one of the two activities, encoded a 349-aa ORF, which was homologous to PBCV-1 A215L and CVN1 CL-2. The vAL-1 gene was expressed at relatively early stages of the virus life cycle; transcripts and translation products appeared at 60 and 90 min postinfection, respectively. The vAL-1 protein was not incorporated into the viral particles but remained in the cell lysate, suggesting a role in the digestion of the cell wall before viral release at the final stage of infection. Cell wall materials isolated from Chlorella strain NC64A cells were digested by vAL-1 and degradation products were detected on TLC. In addition to Chlorella strain NC64A, vAL-1 lysed cells of four C. vulgaris strains as well as Chlorella sp. SAG-241-80.

Amino Acid Sequence↗

PubMed2000

The Difference in Saccadic Parameters Among Several Visually Guided Tasks.

Purpose: The present study was undertaken to establish the effects of the five different paradigms (simultaneous, gap, overlap, delayed-memory, and anti-saccade tasks) on saccade dynamics (duration, peak velocity, and amplitude).Methods: We recorded ocular movements in 7 normal subjects, using infrared oculography with a visual stimulation system.Results: The distribution of saccade accuracy in gap and overlap tasks had about the same steepness as that in simultaneous tasks, but that in delayed-memory and anti-saccade tasks was broader than that in simultaneous tasks. The distribution in anti-saccade tasks had a marked intersubject variability, and the average values of accuracy were hypermetric in four subjects. The peak velocity/amplitude ratio in simultaneous and gap tasks were higher than those of other tasks. The relationship between average of peak velocity of abduction and adduction was different, adduction was higher than abduction in simultaneous and gap tasks, and abduction was lower than adduction in delayed-memory and anti-saccade tasks.Conclusions: The dynamics in simultaneous tasks had about the same characteristics as in gap tasks, but were different from those in overlap, delayed-memory, and anti-saccade tasks. These results indicated that the marked differences in dynamic properties among different saccade types may reflect processes in the visuomotor system.

Journal Article↗

PubMed2000

Analysis of enzymatically glucosylated flavonoids by capillary electrophoresis.

HPCE with UV detection was applied to the analyses of enzymatically glucosylated flavonoids, which are used as natural food additives in Japan. Four items, which have flavonol or flavanone as aglycone, were analyzed. Each of these items is a mixture of glycosides with various lengths of maltooligosaccharide chain. On capillary zone electrophoresis with an untreated fused-silica capillary at alkaline pH, glycosides with longer sugar chains migrated more rapidly. Flavonol glycosides with 1-13 glucose units were distinguished with the borate buffer (pH 10.0). Flavanone glycosides needed higher pH values for good separation than flavonol glycosides.

Buffers↗

PubMed2000

Light and glutamate-induced degradation of the circadian oscillating protein BMAL1 during the mammalian clock resetting.

Recently discovered mammalian clock genes are believed to compose the core oscillator, which generates the circadian rhythm. BMAL1/CLOCK heterodimer is the essential positive element that drives clock-related transcription and self-sustaining oscillation by a negative feedback mechanism. We examined BMAL1 protein expression in the rat suprachiasmatic nuclei (SCN) by immunoblot analysis. Anti-BMAL1 antiserum raised against rBMAL1 recognized 70 kDa mBMAL1b and detected a similar immunoreactivity (IR) as a major band in rat brains. Robust circadian BMAL1-IR oscillations with nocturnal peaks were detected in the SCN during a light/dark cycle and under constant darkness. A short duration light exposure at night acutely reduced BMAL1-IR in the SCN during photoentrainment. This might be attributable to the degradation of BMAL1 protein. Application of glutamate and NMDA to the SCN slices at projected night, a procedure mimicking photic phase delay shift, also acutely reduced BMAL1-IR in a similar manner. A rapid decrease of BMAL1 protein suggests that BMAL1 protein might be implicated in the light-transducing pathway within the SCN.

ARNTL Transcription Factors↗

PubMed2000

Stretch-induced morphological changes of human endothelial cells depend on the intracellular level of Ca2+ rather than of cAMP.

When exposed to a uni-axial cyclic stretch, cultured human umbilical vein endothelial cells (HUVECs) align and elongate perpendicular to the stretch axis. Previous studies showed that forskolin inhibited stretch-induced orientation of endothelial cells, suggesting that adenosine 3:5-cyclic monophosphate (cAMP) plays an important role in the shape change. However, we have recently shown that stretch-induced shape changes in cultured HUVECs are due to increased [Ca2+]i. In the present study, we examined the possible role of cAMP in stretch-induced shape changes in cultured HUVECs. Application of uni-axial cyclic stretch induced a gradual rise in cAMP reaching a peak level at 60 min after the onset of stretch. The adenylate cyclase activator, forskolin, increased the basal level of cAMP but inhibited the rise in [Ca2+]i resulting in no cell shape changes. In contrast, N 6,2-dibutyryladenosine 3:5-cyclic monophosphate (dbcAMP) enhanced the stretch-induced increase in cAMP and [Ca2+]i and resulted in cell shape changes. On the other hand, 2'5'-dideoxyadenosine (DDA), an adenylate cyclase inhibitor, inhibited stretch-induced increases in cAMP and [Ca2+]i resulting in no cell shape changes. In summary, our data showed that cell shape changes were consistently dependent on [Ca2+]i rather than cAMP levels. We conclude that the primary second messenger in the stretch-induced shape changes in HUVECs is intracellular Ca2+ rather than cAMP.

Adenylyl Cyclase Inhibitors↗

PubMed2000

Inorganic Polyphosphate/ATP-NAD kinase of Micrococcus flavus and Mycobacterium tuberculosis H37Rv.

An enzyme with both inorganic polyphosphate [poly(P)]- and ATP-dependent NAD kinase activities was isolated from Micrococcus flavus. The enzyme was a dimer consisting of 34 kDa subunits, and was named poly(P)/ATP-NAD kinase. Internal amino acid sequences of the enzyme showed homologies with some function-unknown proteins released on the GenBank database. Among such proteins, hypothetical Rv1695 protein (Accession No. Z98268-16), which was encoded by a gene named "Rv1695" on genomic DNA of Mycobacterium tuberculosis H37Rv, was proposed to be poly(P)-dependent NAD kinase. By cloning and expression in Escherichia coli, Rv1695 was shown to encode poly(P)/ATP-NAD kinase and named ppnk. The ppnk product, recombinant-poly(P)/ATP-NAD kinase (Ppnk) was purified and characterized. The enzyme was a tetramaer consisting of 35 kDa subunits when expressed in E. coli. Poly(P)/ATP-NAD kinases of M. flavus and Ppnk of M. tuberculosis H37Rv specifically and completely phosphorylated NAD by utilizing commercially available poly(P)s and nucleoside triphosphates as phosphoryl donors.

Amino Acid Sequence↗

PubMed2000

Anatomic distribution of intraprostatic lymphatics: implications for the lymphatic spread of prostate cancer-a preliminary study.

BACKGROUND: Although prostate cancer metastasizes primarily into the lymphatic system, the anatomic distribution of intraprostatic lymphatics has not been elucidated. The aim of this study was to clarify the distribution of lymphatics in the human prostate by immunohistochemical techniques, using an anti-desmoplakin antibody. METHODS: Whole-mount cryostatic sections were serially cut from the noncarcinomatous prostates of adult men with bladder carcinoma who underwent cystoprostatectomy. Each section was stained either with a monoclonal antibody specific for desmoplakin or with hematoxylin and eosin. RESULTS: Lymphatics were detected in all components of the prostate. In the glandular prostate, lymphatics were distributed evenly in the peripheral, transitional, and central zones. The lymphatic density was significantly high in the midbase region surrounding ejaculatory ducts. CONCLUSIONS: These results may indicate the importance of the midbase region as a route of lymphatic spread of prostate cancer.

Aged↗

PubMed2000

Effect of combined leukotriene D(4) and thromboxane A(2) receptor antagonist on mediator-controlled resistance in guinea pigs.

The effects of YM158 (3-[(4-tert-butylthiazol-2-yl)methoxy]-5'-[3-(4-chlorobenzenesu lfonyl )propyl]-2'-(1H-tetrazol-5-ylmethoxy)benzanilide monosodium salt monohydrate), a new dual antagonist for leukotriene D(4) and thromboxane A(2) receptors, on antigen-induced increases in airway resistance were investigated in mediator-controlled novel asthmatic models using actively sensitized guinea pigs. While the predominant mediator was thromboxane A(2), complete inhibition of cyclooxygenase induced mediation by cysteinyl-leukotrienes. About 1-mg/kg indomethacin induced a state where both mediators participated equally. YM158 inhibited increases in resistance whether only one or both mediators were involved. When leukotriene D(4) and thromboxane A(2) equally participated, ED(50) values for 4-oxo-8-[4-(4-phenylbutoxy)benzoylamino]-2-(tetrazol-5-yl)-4 H-1-benzo pyran hemihydrate (pranlukast; 3.9 mg/kg) and 7-(3,5,6-trimethyl-1, 4-benzoquinon-2-yl)-7-phenylheptanoic acid (seratrodast; 2.1 mg/kg) were similar to that for YM158 (8.3 mg/kg), although those effects on the corresponding mediator-induced reaction were 10 times stronger than those of YM158. Additionally, the maximum inhibition of YM158 was stronger than those of either single receptor antagonist. In conclusion, YM158 has a potentially greater efficacy in wider types of experimental asthmatic models than single receptor antagonists.

Administration, Oral↗

PubMed2000

The Difference in Saccadic Parameters among Several Visually Guided Tasks-Saccadic Reaction Time.

Purpose: The saccadic reaction time (SRT) was measured as a saccadic movement parameter using visually guided tasks.Subjects and Method: The SRT was measured for nine healthy adult subjects aged from 28 to 49 years. The visually guided tasks for saccadic movement induction were simultaneous, gap, overlap, delayed-memory, and anti-SM tasks.Results: The median of the SRT (msec) for each task in the actual measurements was as follows: 216 for the simultaneous task, 180 for the gap task, 240 for the overlap task, 234 for the delayed-memory task, and 292 for the anti-SM task. The SRT distribution of each subject exhibited two peaks for the gap task but mostly one peak for each of the other tasks. The first peak, observed in the SRT distribution for the gap task was an eysress saccade.Conclusion: The SRT for the gap task was the shortest and the SRT got longer in the order of the simultaneous task, and the overlap task, and the anti-SM task. Some subjects easily showed an express saccade in the gap task, but others did not.

Journal Article↗

PubMed2000

Transactivation of the multidrug resistance 1 gene by T-cell factor 4/beta-catenin complex in early colorectal carcinogenesis.

The mutational inactivation of a tumor suppressor gene, adenomatous polyposis coli (APC), results in the accumulation of cytoplasmic beta-catenin protein and the activation of T-cell factor (TCF)/lymphoid enhancer factor transcriptional factors. A colorectal carcinoma cell line, DLD-1, was engineered to suppress transactivation by the TCF4/beta-catenin complex in a dominant-negative manner under the strict control of the tetracycline regulatory system. A large-scale comparison of the expression profiles, using two-color fluorescence hybridization of cDNA microarray, led to the identification of MDR1 as a target gene of the TCF4/beta-catenin complex. Luciferase reporter and gel retardation assays revealed the TCF4/beta-catenin responsive elements in the promoter of the human MDR1 gene. Corresponding to the accumulation of beta-catenin, expression of the MDR1 gene product was steadily up-regulated in adenomas and adenocarcinomas of 10 patients with familial adenomatous polyposis. In combination with cell proliferative activities of c-myc and cyclin D1, MDR1 may initiate colorectal tumorigenesis by suppressing cell death pathways programmed in intestinal epithelial cells.

ATP Binding Cassette Transporter, Subfamily B, Mem↗

PubMed2000

Intractable pediatric chronic sinusitis with antrochoanal polyp.

It has been reported that pediatric chronic sinusitis with antrochoanal polyp is difficult to cure because it tends to recur easily even with surgery. Therefore, in order to improve its cure rate, aggressive treatment combining polypectomy, intra-maxillary intubation through the inferior meatus, macrolide administration, etc., was attempted. Thirty-seven sides of pediatric chronic sinusitis with antrochoanal polyp and 44 sides of chronic sinusitis without polyp were evaluated after the same treatments. The mean age of patients was 9.7 years, and the mean intubation period was 20 months. Since subjective improvements in children are questionable, the efficacy was evaluated strictly on the basis of X-ray alone focusing on the maxillary sinus. Twenty-four percent of the group with antrochoanal polyp showed 'excellent' effect, i.e. almost complete resolution of the sinus findings, while 45% of the group without polyp showed 'excellent' effect, with a mean follow-up period of 3 years and 6 months. This difference was significant (P<0. 01, chi(2)-test). These results further document the intractableness of chronic sinusitis with choanal polyp in children.

Adolescent↗

PubMed2000

Characterization of two DNase gamma-specific monoclonal antibodies and the in situ detection of DNase gamma in the nuclei of apoptotic rat thymocytes.

Two novel monoclonal antibodies (mAbs), hg302 and hg303, raised against a synthetic peptide corresponding to the basic domain of human DNase gamma, are characterized in detail. In Western blot analysis, hg303 recognizes both wild type and C-terminal Myc-His-tagged human DNase gamma, but does not cross-react with human DNase I family members, DNase I, DNase X, or DNAS1L2. On the other hand, dot blot analysis reveals the fine specificity of hg302; it recognizes human, mouse, and rat DNase gamma, but not other DNase I family DNases under non-denaturing conditions. Furthermore, hg302 efficiently immunoprecipitates wild type, but not C-terminal Myc-His-tagged, human DNase gamma from cell lysates. In immunohistochemical analysis, hg302 strongly recognizes DNase gamma in the nuclei of X-ray irradiation-induced apoptotic, but not normal rat thymocytes. The specific detection of DNase gamma in apoptotic nuclei is confirmed by indirect-immunofluorescence analysis using TNF-alpha-induced apoptotic HeLa S3 cells transfected with DNase gamma. These results, together with the observations that DNase gamma is present in normal thymocytes and its activity is unchanged during the apoptosis, suggest that some molecular change(s), which triggers the activation of DNase gamma, occurs in response to apoptotic stimuli in the basic domain, and hg302 specifically recognizes the activated DNase gamma in immunohistochemical analysis.

Amino Acid Sequence↗

PubMed2000

Functional analysis of five endothelin-B receptor mutations found in human Hirschsprung disease patients.

Several missense mutations of the endothelin-B receptor (EDNRB) associated with Hirschsprung disease have recently been identified. Five mutated EDNRB (A183G, W276C, R319W, M374I and P383L) cDNAs were transiently expressed in several cell lines to examine the effects of these mutations. Ligand-receptor binding experiments demonstrated that all mutants examined here accept endothelins with a high affinity. Especially, the affinity of endothelins to P383L was increased. However, the number of binding sites of A183G, W276C and P383L was markedly decreased. The subcellular localization of these mutant receptors was the same as that of wild-type EDNRB, whereas the amount of protein of each mutant receptor was decreased. All mutant receptors were impaired in intracellular Ca(2+) mobilization. These findings indicate that these missense mutations result in loss of function of EDNRB, and may provide the molecular pathological basis of Hirschsprung disease in some individuals.

Animals↗