Biomedical subjects

Takashi Yamada

Publications and source records attributed to Takashi Yamada.

At least 19 recordsLinked to original sources

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

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↗

PubMed2005

Effects of reduced glycogen on structure and in vitro function of rat sarcoplasmic reticulum Ca2+-ATPase.

The aim of this study was to examine the effects of reduced glycogen concentration on sarcoplasmic reticulum (SR) Ca(2+)-ATPase activity in rat fast-twitch muscles. In the first experiment, the gastrocnemius (GAS) muscle from one leg was removed, followed by starvation for 24-72 h, after which the remaining GAS was removed. Intra-animal comparisons revealed that starvation caused a 25% reduction (P<0.05) in the glycogen concentration but no change in SR Ca(2+)-ATPase activity in the GAS. In the second experiment, the SR was purified from a mixture of the GAS and vastus lateralis muscles. In half of the samples obtained from each animal, glycogen was extracted from the SR by treatment with glucoamylase. Treatment resulted in a 94.1 and 70.2% decrease (P<0.01) in glycogen and glycogen phosphorylase, respectively, and a 41.5% increase (P<0.05) in a fluorescein isothiocyanate (FITC) binding to SR Ca(2+)-ATPase. On the other hand, SR Ca(2+)-ATPase activity and the affinity of the enzyme for ATP were unaltered. These results do not implicate depletion of muscle glycogen as a contributor to impaired SR Ca(2+)-ATPase activity as measured in vitro. Therefore, it is concluded that muscle glycogen does not influence exercise tolerance and work productivity in working muscles by modulating the structure of protein involved in Ca(2+) sequestering. Furthermore, it is suggested that the FITC binding assay may be inappropriate as a method for examining the mechanisms for the altered activity of SR Ca(2+)-ATPase.

Animals↗

PubMed2005

Amino acid ester salt recognition by ferrocene-based ditopic receptor bearing oligoethylene glycol with pendant bipy subunits: CV, UV-vis and ESR studies.

The novel ferrocene-based ditopic receptor 1 was synthesized. This receptor bears two oligoethylene glycol arms with pendant 2,2'-bipyridine unit at the identical cyclopentadienyl rings, Cu(I) cation binds to 1 to form the 1 : 1 complex (1.Cu(I)) with the cavity consisting of polyether, and the resulting complex acts as a receptor for amino acid ester salts to give the ditopic complex (1.Cu(I).AAOMe-HCl). The 1H NMR spectrum of 1.Cu(I).LeuOMe-HCl exhibits strong broadening at the bipyridine region, and the ESR spectrum of the same sample gives the signals assigned as Cu(II) species. With these data, the binding of 1.Cu(I) towards AAOMe.HCl leads to the conformational change, and the Cu(I) complex is simultaneously oxidized to the Cu(II) complex.

Amino Acids↗

PubMed2005

Immunization with a gene encoding granulocyte-macrophage colony-stimulating factor inserted with a single helper T-cell epitope of an intracellular bacterium induces a specific T-cell subset and protective immunity.

We evaluated here the effect of immunization with a gene encoding granulocyte-macrophage colony-stimulating factor (GM-CSF) inserted with a helper T cell (Th) epitope, listeriolysin O (LLO) 215-226 derived from Listeria monocytogenes on induction of a specific Th by gene gun bombardment. Immunization of C3H/He mice with pGM215m plasmid encoding murine GM-CSF inserted with LLO 215-226 Th epitope gave the epitope-specific proliferative responses of CD4(+) T lymphocytes. In addition, specific interferon-gamma production from the splenocytes was observed. Concomitantly, pGM215m-immunized mice showed significant protective immunity against lethal listerial challenge. These results suggest that immunization of a gene for GM-CSF inserted with a Th epitope is useful for eliciting a specific Th subset in vivo.

Animals↗

PubMed2005

Genetic rearrangements on the Chlorovirus genome that switch between hyaluronan synthesis and chitin synthesis.

Chlorella viruses or chloroviruses form polysaccharide fibers on the cell wall of host Chlorella cells after infection. Such polysaccharides are either hyaluronan synthesized by virus-encoded hyaluronan synthase (HAS) or chitin synthesized by viral chitin synthase (CHS). Some chloroviruses synthesize both hyaluronan (HA) and chitin simultaneously. To understand the relationship between "HA-synthesizing" and "chitin-synthesizing" viruses, we characterized the CVK2 genomic regions, one flanking chs and the other corresponding to PBCV-1 has and found that on CVK2 DNA, a single ORF (PBCV-1 A330R) was replaced with a 5 kbp region containing chs, ugdh2 (the second gene for UDP-glucose dehydrogenase) and two other ORFs, and that has was replaced with another chs gene. In some chloroviruses, ugdh was lost. These results suggest that chlorovirus types changed from "has viruses" to "chs viruses" or from "chs viruses" to "has viruses" by exchanging the genes.

Base Sequence↗

PubMed2005

Distinct conformation-mediated functions of an active site loop in the catalytic reactions of NAD-dependent D-lactate dehydrogenase and formate dehydrogenase.

The three-dimensional structures of NAD-dependent D-lactate dehydrogenase (D-LDH) and formate dehydrogenase (FDH), which resemble each other, imply that the two enzymes commonly employ certain main chain atoms, which are located on corresponding loop structures in the active sites of the two enzymes, for their respective catalytic functions. These active site loops adopt different conformations in the two enzymes, a difference likely attributable to hydrogen bonds with Asn97 and Glu141, which are also located at equivalent positions in D-LDH and FDH, respectively. X-ray crystallography at 2.4-A resolution revealed that replacement of Asn97 with Asp did not markedly change the overall protein structure but markedly perturbed the conformation of the active site loop in Lactobacillus pentosus D-LDH. The Asn97-->Asp mutant D-LDH exhibited virtually the same k(cat), but about 70-fold higher K(M) value for pyruvate than the wild-type enzyme. For Paracoccus sp. 12-A FDH, in contrast, replacement of Glu141 with Gln and Asn induced only 5.5- and 4.3-fold increases in the K(M) value, but 110 and 590-fold decreases in the k(cat) values for formate, respectively. Furthermore, these mutant FDHs, particularly the Glu141-->Asn enzyme, exhibited markedly enhanced catalytic activity for glyoxylate reduction, indicating that FDH is converted to a 2-hydroxy-acid dehydrogenase on the replacement of Glu141. These results indicate that the active site loops play different roles in the catalytic reactions of D-LDH and FDH, stabilization of substrate binding and promotion of hydrogen transfer, respectively, and that Asn97 and Glu141, which stabilize suitable loop conformations, are essential elements for proper loop functioning.

Amino Acid Sequence↗

PubMed2005

Magnetic resonance image findings of placental lake: report of two cases.

Two cases with a large cystic mass within the placenta are reported. By ultrasonography, it was found that both women had a subchorionic hypoechoic lesion (11.0 x 4.8 x 4.0 cm and 6.6 x 3.7 x 2.2 cm, respectively) at 24 and 35 weeks of gestation, respectively. In both cases, turbulent blood flow generated by a pulsatile jet flow (pulse rate; 40 to 60 beats per minute) into the cystic lesion seen on real-time imaging and lesions being low intensity on T1-weighted and isointensity on T2-weighted magnetic resonance image suggested that they contained fresh maternal blood. In both cases, the sonolucency of the lesions did not change until cesarean deliveries of females, both of whom were small-for-gestational-age infants (1940 g at 37 weeks and 2195 g at 37 weeks, respectively). Biochemical analysis of the fluid in the cystic lesion sampled during the cesarean section in the latter case confirmed that the fluid had originated from the maternal blood. These lesions histologically corresponded to large avillous areas surrounded by normal villi. Thus, a huge placental lake was diagnosed in both cases.

Adult↗

PubMed2005

Studies on intramolecular hydrogen bonding between the pyridine nitrogen and the amide hydrogen of the peptide: synthesis and conformational analysis of tripeptides containing novel amino acids with a pyridine ring.

For the first time tripeptides, Z-AA(1)-Xaa-AA(3)-OMe (AA(1) and AA(3) = Gly or Aib, Xaa = 2Pmg and 2Pyg) were prepared containing alpha-methyl-alpha-(2-pyridyl)glycine (2Pmg) and alpha-(2-pyridyl)glycine (2Pyg) by solid-phase Ugi reaction. These results clearly indicate that for the preparation of tripeptides containing an amino acid with a pyridine ring, the solid-phase Ugi reaction is very useful.NMR analysis clarified that 2Pmg-containing tripeptides adopt a unique conformation with an intramolecular hydrogen bond between 2Pmg-NH and the pyridine nitrogen. However, in the case of Z-Gly-2Pyg-Gly-OMe, the intramolecular hydrogen bonding between 2Pyg-NH and the pyridine nitrogen was not observed, whereas Z-Aib-2Pyg-Aib-OMe adopts a unique conformation with an intramolecular hydrogen bond between 2Pyg-NH and a pyridine nitrogen. Conformational analysis of the tripeptides, Z-AA(1)-Xaa-AA(3)-OMe (AA(1), AA(3) = Gly or Aib, Xaa = alpha,alpha-di(2-pyridyl)glycine (2Dpy), alpha-phenyl-alpha-(2-pyridyl)glycine (2Ppg), 2Pmg and 2Pyg), clarified that when an alpha,alpha-disubstituted glycine with a 2-pyridyl group at an alpha-carbon atom is introduced into any peptide, an intramolecular hydrogen bond between a pyridine nitrogen and an amide proton is formed and conformational mobility of the peptide backbone is restricted.

Amides↗

PubMed2005

Changes in antithrombin activity and platelet counts in the late stage of twin and triplet pregnancies.

It is possible that women with triplet pregnancies are more likely to exhibit pregnancy-induced antithrombin deficiency, gestational thrombocytopenia, and perinatal elevation in serum aspartate aminotransferase (AST) than women with twin pregnancies. We retrospectively reviewed changes in antithrombin activity, platelet count, and blood chemistry in 23 twin and seven triplet pregnancies in which the mothers received antenatal care and gave birth in our hospital during 1999 and 2001. Both antithrombin activity and platelet counts gradually decreased until delivery, then promptly increased after delivery in both twin and triplet pregnancies. A significantly larger number of women developed gestational thrombocytopenia of < 100 x 10 (9)/L (43% [three of seven] versus 4.3% [one of 23]; p < 0.01) and pregnancy-induced antithrombin deficiency of < 60% of normal activity (57% [four of seven] versus 17% [four of 23]; p < 0.05) in triplet than in twin pregnancies. Eight women with pregnancy-induced antithrombin deficiency, including three women with gestational thrombocytopenia, were significantly more likely to develop perinatal elevations of AST, lactate dehydrogenase, serum creatinine, fibrin/fibrinogen degradation products, and D-dimer than were those without pregnancy-induced antithrombin deficiency. These findings suggest that women with triplet pregnancies are at an increased risk of the HELLP syndrome and acute fatty liver of pregnancy compared with women with twin pregnancies.

Adult↗

PubMed2005

Effects of theanine, r-glutamylethylamide, on neurotransmitter release and its relationship with glutamic acid neurotransmission.

t Theanine, r-glutamylethylamide, is one of the major amino acid components in green tea and many researchers have compared theanine's effects with glutamic acid because the chemical structure is similar. In the previous study, we demonstrated that theanine can pass brain-blood barrier and may play as an agonist or an antagonist of some receptors. In this study, we investigated the effects of theanine on neurotransmitter release in the rat brain striatum by in vivo brain microdialysis and examined whether theanine affected glutamate transporters by comparing it with a glutamate transporter blocker, L-trans-Pyrrolidine-2,4-dicarboxylic acid (L-trans-2,4-PDC). Because we investigated whether the effects of theanine is similar to L-trans-2,4-PDC on the brain neurotransmission, we measured dopamine release and some amino acids release which are known as excitatory or inhibitory neurotransmitters from neurons by theanine or L-trans-2,4-PDC perfusion into the rat brain striatum. L-trans-2,4-PDC or theanine perfusion into the brain striatum caused dopamine release from dopaminergic neurons. In addition, L-trans-2,4-PDC perfusion increased glutamic acid, aspartic acid and, whereas theanine perfusion prevented aspartic acid release and increased glycine release. These results suggested that the mechanism of dopamine release caused by theanine is different from glutamate transporter blockers or glutamic acid. Further, L-trans-2,4-PDC cause excitatory neurotransmission, whereas theanine may inhibit excitatory neurotransmission and cause inhibitory neurotransmission via glycine receptors.

Animals↗

PubMed2005

Autologous blood transfusion in patients with placenta previa.

BACKGROUND: Several studies have shown that autologous blood storage during pregnancy is relatively safe for mother and fetus. However, the need for reappraisal of autologous blood transfusion in obstetric patients has been proposed. METHODS: We retrospectively reviewed the cases of placenta previa and low-lying placenta among pregnancies at our hospital during an 18-year period, 1985-2002. The utility of autologous blood transfusion program, which started in 1994 for those with placental positional disorders, was evaluated. RESULTS: Of the pregnancies reviewed, there were 158 cases (1.9%) of placenta previa or low-lying placenta. The number of patients transfused with homologous blood decreased from 27.6% (21/76) in the period before implementation of the autologous blood transfusion program to 8.5% (7/82) after its implementation in 1994. In the latter time period, 39.0% (32/82) of patients with placenta previa and low-lying placenta were phlebotomized and had blood stored. Of those, 71.9% (23/32) were reinfused where one patient (3.1%) needed homologous blood as well. The volume of collected blood per phlebotomy was 367 +/- 65 ml, the total volume of collected blood per patient was 803 +/- 350 ml, and the total of estimated blood loss per patient was 1326 +/- 873 ml. The volume of reinfused blood per patient was 578 +/- 326 ml. CONCLUSIONS: The program of autologous blood collection and transfusion in patients with placenta previa resulted in a decrease in homologous blood transfusion. In our program, we recommend starting blood collection and storage at 32 weeks' gestation and phlebotomize 400 ml per week to reach a volume of stored blood of 1200-1500 ml.

Adult↗

PubMed2005

Evaluation of the ESPLINE INFLUENZA A&B-N Kit for the diagnosis of avian and swine influenza.

The ESPLINE INFLUENZA A&B-N kit was evaluated for its applicability to the rapid diagnosis of influenza in chickens and pigs. The kit specifically detected viral antigens in tracheal swabs and tissue homogenates of the trachea, liver, spleen, and colon of chickens inoculated with a highly pathogenic avian influenza virus strain, A/chicken/Yamaguchi/7/04 (H5N1), at 48 hr post-inoculation (p.i.) as well as in the tracheal and cloacal swabs and tissue homogenates of dead chickens. For those infected with a low pathogenic strain, A/chicken/aq-Y-55/01 (H9N2), antigens were detected only in the samples from tracheal swabs and organs 1-4 days p.i. The kit also detected viral antigens in the nasal swabs of miniature pigs infected with swine and avian influenza viruses. The kit was found to be sensitive and specific enough for the rapid diagnosis of infections of influenza A virus in chickens and pigs.

Animals↗

PubMed2005

Late restenosis of the balloon-dilated site: serial angiographic observations beyond 7 years.

BACKGROUND: The present retrospective study was performed to assess the long-term (>7 years) fate of stabilized balloon-dilated sites. METHODS AND RESULTS: Between February and April 1986, 171 patients underwent successful percutaneous balloon angioplasty. Early restenosis (<1 year) occurred in 53%, but repeat balloon angioplasty stabilized the balloon-dilated site. The early period was defined as 6 months, late years as 3-5 years and long-term years as 7-12 years. Angiographic evaluation at both early year or late year periods (mean = 4.7 years) and long-term (mean = 10.4 years) periods following stabilization was available in 71 patients (94 lesions) with mean age of 61.7+/-8.5 years. Of the 71 patients 69.6% were male. Restenosis occurring after 1 year was defined as late restenosis. The mean diameter stenosis changed from 6 months (50.3+/-12.4%) to late-period (44.2 +/-13.2%; p < 0.05) and long-term period (50.3+/-16.1%; p < 0.001); but the reference vessel diameter did not change significantly. Late restenosis occurred in 28% (3-5 years) and 33% (7-12 years) of 94 lesions, and 13.8% of lesion required repeat target lesion revascularization. During this period, 5.3% of patients (5 lesions) underwent revascularization for new proximal or distal lesions. CONCLUSIONS: Decrease of luminal diameter during the early 6 months, was followed by regression after stabilization of the balloon-dilated site up to 5 years, but luminal re-narrowing occurs again over 7 years after balloon angioplasty.

Aged↗