Biomedical subjects

Takashi Yamada

Publications and source records attributed to Takashi Yamada.

At least 19 recordsLinked to original sources

PubMed2007

Effects of high-intensity training and acute exercise on in vitro function of rat sarcoplasmic reticulum.

To evaluate the effects of high-intensity training and/or a single bout of exercise on in vitro function of the sarcoplasmic reticulum (SR), the rats were subjected to 8 weeks of interval running program (final training: 2.5-min running x 4 sets per day, 50 m/min at 10% incline). Following training, SR function, i.e., Ca2+-ATPase activity and Ca2+-uptake and release rates, was examined in homogenates of the superficial region of the vastus lateralis muscle from rats subjected to a single bout of treadmill running (50 m/min at 10% incline) for 2.5 min or to exhaustion. Training brought about a 12.4% increase (P < 0.05) in SR Ca2+-uptake rate in rested muscles. This change was not accompanied by alterations in Ca2+-ATPase activity, Ca2+-release rate, Ca2+ dependence of enzyme and protein contents of Ca2+-ATPase and ryanodine receptor. A single bout of high-intensity exercise to exhaustion evoked significant reductions (P < 0.05) in SR function, irrespective of whether or not the animals were trained. For 2.5-min run and exhausted rats, no differences existed between SR functions of untrained and trained muscles. These data suggest that high-intensity training may be capable of enhancing SR Ca2+-sequestering ability, and may not protect against decreasing SR function with high-intensity exercise.

Animals↗

PubMed2006

Genome shuffling of Streptomyces sp. U121 for improved production of hydroxycitric acid.

(2S, 3R)-Hydroxycitric acid (HCA) from Hibiscus subdariffa inhibits pancreatic alpha-amylase and intestine alpha-glucosidase, leading to reduction of carbohydrate metabolism. In our previous study, Streptomyces sp. U121 was identified as a producer of (2S, 3R)-HCA [Hida et al. (2005) Bioscience, Biotechnology, and Biochemistry 69:1555-1561]. Here, we applied genome shuffling of Streptomyces sp. U121 to achieve rapid improvement of HCA production. The initial mutant population was generated by nitrosoguanidine treatment of the spores, and an improved population producing fivefold more HCA over wild type was obtained by three rounds of genome shuffling. For efficient screening of the mutant library, trans-epoxyaconitic acid (EAA), an antibiotic analog of HCA, was utilized. EAA inhibited the regeneration of nonfused protoplasts, resulting in selective screening of shuffled strains. Mutant strains with enhanced EAA resistance exhibited significantly higher HCA production in liquid media. Furthermore, the best mutant showed increased cell growth in flask culture, as well as increased HCA production.

Anti-Bacterial Agents↗

PubMed2006

Effect of methimazole treatment for 2 years on circulating IL-4, IgE, TBII, and TSAb in patients with hyperthyroid Graves' disease.

In this study we confirmed our previous findings on the importance of IgE in Graves' disease and further investigated the relationships existing among Graves' disease, IgE, and interleukin-4. Two hundred and thirty-two newly diagnosed Graves' disease patients were treated with methimazole for 2 years, and were classified into 3 groups according to their response to the therapy. Incidence of IgE elevation (IgE> or =170 IU/ml) before treatment was lowest, 23.8%, in the group who achieved remission without recurrence, while it was 41.7% in the group who achieved remission but recurrence occurred within 4 years. Incidence of IgE elevation before treatment was highest, 60.7%, in the group who failed to achieve remission, significantly higher than that of the group without recurrence. Incidence of IgE elevation before treatment in all these patients of Graves' disease were 35.3%, significantly higher than those of Hashimoto's thyroiditis (17.5%) and of simple goiter (7.0%). Serum IL-4 levels before treatment were significantly higher in the patients of Graves' disease with IgE elevation than in those without IgE elevation. Serum T4 concentration and TSAb titration before treatment were also significantly higher in elevated IgE group than in normal IgE group. These results support our previous findings and suggest that IL-4 may play important roles in the elevation of IgE, TBII, and TSAb in patients of Graves' disease, and that IL-4 and IgE may be involved in the development, progression, and maintenance of Graves' disease.

Adolescent↗

PubMed2006

C-terminal repetitive motifs in Vp130 present at the unique vertex of the Chlorovirus capsid are essential for binding to the host Chlorella cell wall.

Previously, Vp130, a chloroviral structural protein, was found to have host-cell-wall-binding activity for NC64A-viruses (PBCV-1 and CVK2). In this study, we have isolated and characterized the corresponding protein from chlorovirus CVGW1, one of Pbi-viruses that have a different host range. In NC64A-viruses, Vp130 consists of a highly conserved N-terminal domain, internal repeats of 70-73 aa motifs and a C-terminal domain occupied by 23-26 tandem repeats of a PAPK motif. However, CVGW1 was found to have a slightly different Vp130 construction where the PAPK repeats were not in the C-terminus but internal. Immunofluorescence microscopy with a specific antibody revealed that the C-terminal region containing the Vp130 repetitive motifs from PBCV-1 and CVK2 was responsible for binding to Chlorella cell walls. Furthermore, by immunoelectron microscopy and immunofluorescence microscopy, Vp130 was localized at a unique vertex of the chlorovirus particle and was found to be masked through binding to the host cells. These results suggested that Vp130 is localized at a unique vertex on the virion, with the C-terminal repetitive units outside for cell wall binding.

Amino Acid Sequence↗

PubMed2006

Carminerin contributes to chondrocyte calcification during endochondral ossification.

Endochondral ossification is an essential process not only for physiological skeletal development and growth, but also for pathological disorders. We recently identified a novel cartilage-specific molecule, carminerin (also known as cystatin 10 and encoded by Cst10), which is upregulated in synchrony with cartilage maturation and stimulates the later differentiation of cultured chondrocytes. Although carminerin-deficient (Cst10-/-) mice developed and grew normally, they had a microscopic decrease in the calcification of hypertrophic chondrocytes at the growth plate. When we created experimental models of pathological endochondral ossification, we observed suppression of chondrocyte calcification during formation of osteoarthritic osteophytes, age-related ectopic ossification and healing of bone fractures in Cst10-/- mice. Cultured Cst10-/- chondrocytes showed a reduction in calcification with activation of an SRY site in the promoter of the gene encoding nucleotide pyrophosphatase phosphodiesterase 1 (NPP1, encoded by Enpp1). Functional NPP1 is required for carminerin deficiency to suppress the pathological endochondral ossifications listed above. Carminerin is the first cartilage-specific protein that contributes to chondrocyte calcification during endochondral ossification under physiological and pathological conditions through the transcriptional inhibition of NPP1.

Animals↗

PubMed2006

Photoelectrochemical oxidation of methanol on oxide nanosheets.

Photoelectrochemical oxidation of alcohol on various nanosheet electrodes such as Nb6O17, Ca2Nb3O10, Ti(0.91)O2, Ti4O9, and MnO2 system host layers were measured to evaluate the photocatalysis of water photolysis with alcohol as a sacrificial agent. The nanosheet electrodes were prepared by the layer-by-layer (LBL) method, using electrostatic principles. The highest photooxidation current density was observed in methanol solution for Nb6O17 and Ca2Nb3O10 nanosheets, while the density was lower for Ti(0.91)O2, Ti4O9, and MnO2 nanosheets in decreasing order. The rank in the photocurrent density was in agreement with that in the photocatalytic activity, which means that the degree of photooxidation of the alcohol determines the activity of the alcohol in the water photolysis process. The photocurrent was independent of the number of nanosheet layers on the electrode, indicating that only the mono-nanosheet layer attached directly on a substrate acts as a photoelectrocatalyst and that the interlayer space is not important. Consequently, higher photooxidation current on the Nb6O17 mono-nanosheet layer means that the charge separation of electron and hole under illumination is very large and that the hole-capturing process by CH3OH is very quick compared with the surface recombination on the Nb6O17 nanosheet. The adsorption of a transition metal cation on the nanosheet acted as the surface recombination center, because the photocurrent decreased after the adsorption. The photocatalytic mechanism has been discussed in detail in terms of various photoelectrochemical behaviors.

Journal Article↗

PubMed2006

Oxidation of myosin heavy chain and reduction in force production in hyperthyroid rat soleus.

We tested the hypothesis that a force reduction in hyperthyroid rat soleus muscle would be associated with oxidative modification in myosin heavy chain (MHC). Daily injection of thyroid hormone [3,5,3'-triiodo-L-thyronine (T3)] for 21 days depressed isometric forces of whole soleus muscle across a range of stimulus frequencies (P < 0.01). In fiber bundles, hyperthyroidism also led to pronounced reductions (P < 0.01) in both K+ - and 4-chloro-m-cresol-induced contracture forces. The degrees of the reductions were similar between these two contractures that were induced by distinct reagents. Treatment with T3 elicited a significant decrease ( approximately 14%; P < 0.05) in the relative content of MHC contained in myofibrillar proteins. The content of carbonyl groups in myofibrillar protein extracts was elevated (P < 0.05) by approximately 50% in T3-treated muscles. Immunoblot analyses on T3-treated muscles showed a greater increase (106%; P < 0.05) of the carbonyl content in MHC than in myofibrillar protein extracts. These data suggest that in hyperthyroidism the decrease in force production of skeletal muscles may stem primarily from failure in myofibrillar protein function resulting from oxidative modification of MHC.

Animals↗

PubMed2006

Enhancement of enantioselectivity in the Bacillus subtilis protease-catalyzed hydrolysis of N-free amino acid esters using the ester grouping-modification approach.

The generality of enantioselectivity enhancement through the modification of the alcohol moiety of a substrate ester was ascertained, for in the Bacillus subtilis protease-catalyzed hydrolysis of N-unprotected amino acid esters the enantioselectivity was enhanced largely by switching the conventional methyl ester to esters with a longer alkyl chain such as the isobutyl ester (from E = 3 to E = 130-170 in the case of 4-fluorophenylalanine esters) as in the enzymatic hydrolysis mediated by Aspergillus oryzae protease. There was indeed a profound dependence of E on the nature of the ester grouping.

Amino Acids↗

PubMed2006

Chlorella viruses.

Chlorella viruses or chloroviruses are large, icosahedral, plaque-forming, double-stranded-DNA-containing viruses that replicate in certain strains of the unicellular green alga Chlorella. DNA sequence analysis of the 330-kbp genome of Paramecium bursaria chlorella virus 1 (PBCV-1), the prototype of this virus family (Phycodnaviridae), predict approximately 366 protein-encoding genes and 11 tRNA genes. The predicted gene products of approximately 50% of these genes resemble proteins of known function, including many that are completely unexpected for a virus. In addition, the chlorella viruses have several features and encode many gene products that distinguish them from most viruses. These products include: (1) multiple DNA methyltransferases and DNA site-specific endonucleases, (2) the enzymes required to glycosylate their proteins and synthesize polysaccharides such as hyaluronan and chitin, (3) a virus-encoded K(+) channel (called Kcv) located in the internal membrane of the virions, (4) a SET domain containing protein (referred to as vSET) that dimethylates Lys27 in histone 3, and (5) PBCV-1 has three types of introns; a self-splicing intron, a spliceosomal processed intron, and a small tRNA intron. Accumulating evidence indicates that the chlorella viruses have a very long evolutionary history. This review mainly deals with research on the virion structure, genome rearrangements, gene expression, cell wall degradation, polysaccharide synthesis, and evolution of PBCV-1 as well as other related viruses.

Base Sequence↗

PubMed2006

Effect of gonadotropin-releasing hormone agonist on a uterine arteriovenous malformation.

BACKGROUND: The effect of gonadotropin-releasing hormone agonist (GnRHa) on uterine arteriovenous malformations (AVM) is not well known. CASE: A 37-year-old woman with a previous cesarean was diagnosed as having a uterine AVM after a spontaneous abortion with massive vaginal bleeding. The AVM decreased in size from 5.1 x 3.8 cm to 1.4 x 1.0 cm after 6 months of therapy with a GnRHa. Uterine artery embolization conducted after the GnRH therapy resulted in complete disappearance of the AVM. The patient's menstrual cycles and ovulation resumed 3 months after uterine artery embolization. CONCLUSION: Gonadotropin-releasing hormone agonist therapy reduced the size of the uterine AVM. Thus, GnRHa therapy may be useful for uterine AVM in situations where uterine artery embolization must be postponed.

Abortion, Spontaneous↗

PubMed2006

Functional maternal catechol-O-methyltransferase polymorphism and fetal growth restriction.

OBJECTIVES: The pathophysiologic processes that occur at the cellular and molecular levels in intrauterine fetal growth restriction are largely unknown. Catechol-O-methyltransferase (COMT) is a phase II enzyme that inactivates catechol estrogens by transfer of a methyl group. A functional Val158Met polymorphism in the COMT gene has been known as a susceptible marker for breast cancer. The aim of this study was to examine the association between this polymorphism and fetal growth. METHODS: A consecutive series of 412 women who experienced singleton deliveries was assessed in the birth cohort study. Genotyping of COMT and CYP17A1 polymorphisms was determined by allelic discrimination using fluorogenic probes and the 5'nuclease assay. RESULTS: The adjusted odds ratio for the risk of low birth weight (<2.500 g) in women with homozygous low-activity (COMT-L) alleles was 2.98 (95% confidence interval, 1.10-8.11). The mean birth weight of infants whose mothers were homozygous for COMT-L was less than that of infants whose mothers had at least one high-activity (COMT-H) allele (2.610 versus 2.800 g, P=0.07). The odds ratio for the risk of intrauterine fetal growth restriction, defined as birth weight <10th percentile or <mean-1.5 SD, in women homozygous for COMT-L alleles was 2.63/2.57 (95% confidence interval, 1.14-6.05/0.96-6.88). In the recessive genotype model, the odds ratios for the risk of low birth weight and intrauterine fetal growth restriction in women homozygous for COMT-L were 3.36 (95% confidence interval, 1.30-8.65) and 2.89/2.65 (95% confidence interval, 1.31-6.34/1.06-6.65), respectively. A positive association exists between birth weight and the homozygous CYP17A1 A2 genotype (P<0.01). When both COMT and CYP17A1 genotypes were considered, the highest risk of low birth weight/intrauterine fetal growth restriction was found among women with the homozygous COMT-L and CYP17A1 A1 genotype. The odds ratio for the risk of intrauterine fetal growth restriction (<10th percentile) in those women was 5.35 (95% confidence interval, 1.15-25.0). CONCLUSION: Our findings suggest that the allele encoding low-activity COMT may be a susceptible marker for intrauterine fetal growth restriction.

Adolescent↗

PubMed2006

A validation and potential modification of the pneumonia severity index in elderly patients with community-acquired pneumonia.

OBJECTIVES: To evaluate the discriminatory power of the Pneumonia Severity Index (PSI) in elderly patients with community-acquired pneumonia (CAP) and to improve its performance. DESIGN: Retrospective review of 193 patients from 1999 to 2001 to derive prognostic rules. The rules were prospectively validated in 144 patients from 2002 to 2003. SETTING: Iwata City Hospital, a 400-bed general hospital. PARTICIPANTS: Patients aged 80 and older who had CAP and were admitted to the hospital. MEASUREMENTS: Predictors of 30-day mortality were identified using logistic regression analysis, and several rules were constructed by combining the PSI and the independent predictors. RESULTS: The original PSI, which defines PSI Class IV and V as a high-risk group, did not perform well in discriminating survivors from nonsurvivors (sensitivity 100%, specificity 15%), whereas a modified PSI, which defines only PSI Class V as a high-risk group, performed better (sensitivity 86%, specificity 63%). Three predictors for mortality were identified independent from the modified PSI: performance status (PS) Grade 3 or higher, anorexia, and partial pressure of carbon dioxide of 50 mmHg or greater. By combining the modified PSI and PS, the performance could be further improved (sensitivity 79%, specificity 80%). CONCLUSION: The modified PSI could identify low-risk patients more accurately than the original PSI. In addition, by combining the modified PSI with PS, higher performance was obtained. Such information would aid physicians in clinical decision-making without overestimating the risk for elderly patients with CAP.

Aged, 80 and over↗

PubMed2006

Association between preterm birth and vaginal colonization by mycoplasmas in early pregnancy.

To examine the association between colonization by two newly classified species of genital ureaplasmas (Ureaplasma parvum and U. urealyticum) in early pregnancy and subsequent late abortion or preterm birth at <34 weeks of gestation, four species of genital mycoplasmas--Mycoplasma genitalium, M. hominis, U. parvum, and U. urealyticum--as well as Chlamydia trachomatis and Neisseria gonorrhoeae were examined by PCR-based methods in a prospective cohort study of 877 women with singleton pregnancies at <11 weeks of gestation. Antibiotics were used only in cases in which C. trachomatis and/or N. gonorrhoeae was detected. Multivariate logistic-regression analysis was used to assess independent risk factors after taking maternal low body weight and past history of preterm birth into account. M. genitalium, M. hominis, U. parvum, U. urealyticum, C. trachomatis, and N. gonorrhoeae were detected in 0.8%, 11.2%, 52.0%, 8.7%, 3.2%, and 0.1% of these 877 women, respectively. Twenty-one (2.4%) women experienced late abortion or preterm birth at <34 weeks of gestation. Three factors-detection of U. parvum in the vagina (odds ratio [OR], 3.0; 95% confidence interval [CI], 1.1 to 8.5); use of antibiotics, such as penicillin and cefatrizine, for incidental inflammatory complications before 22 weeks of gestation (OR, 4.2; 95% CI, 1.6 to 10.0); and past history of preterm birth (OR, 10.4; 95% CI, 2.7 to 40.5)-were independently associated with late abortion and preterm birth. In conclusion, vaginal colonization with U. parvum, but not U. urealyticum, is associated with late abortion or early preterm birth.

Adult↗

PubMed2006

Prenatal diagnosis and therapy of persistent cloaca: a case report.

Persistent cloaca is a rare abnormality that occurs only in females and is characterized by a direct communication between the gastrointestinal, urinary, and genital structures resulting in a single perineal opening. A case with massive ascites, two cystic structures arising from the fetal pelvis, bilateral hydroureters, calcified meconium, and cardiac anomalies, in which this condition was diagnosed prenatally is presented here.

Adult↗

PubMed2006

ZMVHA-B1, the gene for subunit B of vacuolar H+-ATPase from the eelgrass Zostera marina L. Is able to replace vma2 in a yeast null mutant.

A vacuolar H(+)-ATPase (VHA) gene (ZMVHA-B1) was isolated from an eelgrass (Zostera marina) leaf cDNA library and was characterized to be approximately 1.4 kbp in length and to encode the B subunit protein of VHA comprising 488 amino acids. ZMVHA-B1 was highly expressed in all organs of eelgrass; the expression level was highest in the leaves. On transformation of a yeast vma2 null mutant with ZMVHA-B1, yeast cells became able to grow at pH 7.5, accompanied by the vesicular accumulation of LysoSensor green DND-189. Thus, ZMVHA-B1 expressed in yeast cells produced a functional B subunit that was efficiently incorporated into the VHA complex and eventually restored vacuolar morphology and activity. This success expedites the application of heterologous expression in yeast mutant cells to the screening of eelgrass genes involved in salt-resistance mechanisms, which are to be utilized in improving important crops.

Cloning, Molecular↗

PubMed2006

Absolute configuration of hydroxycitric acid produced by microorganisms.

Optical resolution for (2S,3R) and (2R,3S)-hydroxycitric acid (HCA) enantiomers was developed using chiral column chromatography. HCA from Bacillus megaterium G45C and Streptomyces sp. U121, newly isolated in our previous study, was analyzed to determine the absolute configuration. These results indicate that both strains generate optically pure (2S,3R)-hibiscus type HCA enantiomer.

Bacillus megaterium↗

PubMed2006

Coagulation-fibrinolysis is more enhanced in twin than in singleton pregnancies.

AIMS: To examine whether coagulation-fibrinolysis in late pregnancy in women with twin pregnancies is more pronounced than in women with singleton pregnancies. PATIENTS AND METHODS: The plasma levels of D-dimer, fibrinogen/fibrin degradation products (FDP), and fibrinogen, the platelet count, and the antithrombin activity were assessed from 3 weeks before delivery until postpartum day 7 in 48 women (24 singleton and 24 twin pregnancies) without preeclampsia who underwent cesarean sections. RESULTS: Women with singleton or twin pregnancies gave birth at 37.3+/-1.2 weeks or 35.2+/-1.4 weeks, respectively. Compared with singleton mothers, prenatal D-dimer and FDP levels were consistently and significantly higher among women with twin pregnancies. A significantly larger proportion of twin mothers exhibited prenatal levels of D-dimer >5.0 microg/mL, FDP >10.0 microg/mL, fibrinogen <420 mg/mL and antithrombin activity <70%. In addition, prenatal antithrombin activity in plasma was significantly lower. CONCLUSIONS: Coagulation-fibrinolysis is more enhanced in women with twin gestation than in women with singleton gestation.

Adult↗

PubMed2006

Clinical features of polycythemia vera and essential thrombocythemia in Japan: retrospective analysis of a nationwide survey by the Japanese Elderly Leukemia and Lymphoma Study Group.

We conducted the first nationwide survey to clarify the clinical features, treatment methods, and prognoses for polycythemia vera (PV) and essential thrombocythemia (ET). A 1-page questionnaire was mailed to members of the Japanese Elderly Leukemia and Lymphoma Study Group (JELLSG). Surveys on 647 patients (PV, 266 patients; ET, 381 patients) were returned and analyzed. Thrombotic events at diagnosis and during follow-up occurred at rates of 15.4% and 8.5%, respectively, in PV cases and 17.6% and 8.7% in ET cases. Splenomegaly was observed in only 28.8% of PV patients and 10.8% of ET patients. The leukocyte alkaline phosphatase score was elevated in only 46.2% of PV patients. The incidences of abnormal karyotypes were less than 10% in both PV and ET cases. The rates of transformation to myelofibrosis were 2.6% in both PV and ET cases, and acute leukemia was noted in 1.1% of PV patients and 2.9% of ET patients. Prognostic factors were thrombotic history for PV and thrombotic history and age (>or=60 years) for ET. The present study clearly demonstrated clinical differences between Japanese and Western patients for PV and ET. Concerning the treatment of PV and ET, the study revealed considerable variation among Japanese hematologists. These results suggest the necessity of developing treatment guidelines according to risk stratification that are suitable for Japanese PV and ET patients.

Adolescent↗