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T Ohta

Publications and source records attributed to T Ohta.

At least 595 records · Page 33Linked to original sources
PubMed1996

[Survival factors in healthy aging among rural Japanese residents of Aichi].

To investigate survival factors in healthy aging among rural Japanese elderly residents, a nested case-control study was conducted. Subjects who answered questionnaires in 1985 were followed for 10 years. Cases comprised 124 men and 109 women who, in 1995, were 75 years old or over, and whose activities of daily living were active enough to cope for themselves. Controls were selected from subjects who died between 1987 and 1994. One control per case was randomly selected, and matched to each case for sex and birth-year (+/- 2 years). The survival odds ratio (sOR) was calculated by using a conditional multiple logistic regression model. An sOR greater than 1.0 was observed for frequent intake of eggs, regular daily routine, adaptability to changes, leisure time exercise and a health examination at least once within 3 years. In both men and women present or past history of heart disease, cerebrovascular disease and diabetes, family history of hypertension, and in women, smoking were negatively associated with survival. By multivariate analysis, adaptability to change in men, and regular daily routine and health examinations in women were positively associated to survival. Smoking and history of chronic disease were negatively associated with survival, in both men and women. In conclusion, it is suggested that psychological factors and recent health examinations were positively associated to survival in healthy aging, and habitual smoking and chronic disease contributed negatively to survival. These results require further careful evaluation to determine whether the factors are associated with cause or effect.

Aged↗
PubMed1995

Comparison of primary structures and substrate specificities of two pullulan-hydrolyzing alpha-amylases, TVA I and TVA II, from Thermoactinomyces vulgaris R-47.

Thermoactinomyces vulgaris R-47 produces two alpha-amylases, TVA I, an extracellular enzyme, and TVA II, an intracellular enzyme. Both enzymes hydrolyze pullulan to produce panose, and also hydrolyze cyclodextrins. We cloned and sequenced the TVA I gene. The TVA I gene consisted of 1833 base pairs, and the deduced primary structure was composed of 611 amino-acid residues, including an N-terminal signal sequence consisting of 29 amino-acid residues. The similarity between the amino-acid sequence of mature TVA I with those of other pullulan/cyclodextrin-hydrolyzing enzymes, such as TVA II and Bacillus stearothermophilus neopullulanase, was only 30%, although that of TVA II with neopullulanase was 48%. TVA II prefers specific small oligosaccharides and alpha- and beta-cyclodextrins. Whereas kcat/Km values of TVA I for pullulan were larger than that of TVA II, and TVA II could not hydrolyze starch completely. TVA II was inhibited by maltose, the hydrolysate of starch, which seems to be the reason for inefficient hydrolysis of starch. These kinetic properties indicate that TVA I and TVA II have differential physiological roles in sugar metabolism extracellularly and intracellularly, respectively.

Amino Acid Sequence↗
PubMed1995

Gene of heat shock protein of sulfur-dependent archaeal hyperthermophile Desulfurococcus.

To elucidate thermoresistance, a gene of a hyperthermophilic heat shock protein (HHSP) was isolated from the hyperthermophile Desulfurococcus strain SY which grows at 95 degrees C. The molecular weight of HHSP deduced from the open reading frame was 59,137 (545 amino acid residues). Sequence alignments of peptides reveal similarities (evolutionary distances) to the alpha (0.279) and beta (0.296) subunits of thermosome, TF55 (0.343) and human t-complex polypeptide 1. The structure of a thermophilic heat shock protein TGroEL (Tamada et al. (1991) Biochem, Biophys. Res. Commun. 179, 565) was quite different from that of HHSP. TGroEL and HSP60 have sequences identical to HHSP at its equatorial domain, while those identical to the alpha subunit of F-type ATPase are at its apical domain.

Amino Acid Sequence↗
PubMed1995

Evolutionary conservation of human TATA-binding-polypeptide-associated factors TAFII31 and TAFII80 and interactions of TAFII80 with other TAFs and with general transcription factors.

Human transcription initiation factor TFIID is composed of the TATA-binding polypeptide (TBP) and at least 13 TBP-associated factors (TAFs) that collectively or individually are involved in activator-dependent transcription. To investigate protein-protein interactions involved in TFIID assembly and in TAF-mediated activator functions, we have cloned and expressed cDNAs encoding human TAFII80 and TAFII31. Coimmunoprecipitation assays showed that TAFII80 interacted with TAFII250, TAFII31, TAFII20, and TBP, but not with TAFII55. Similar assays showed that TAFII80 interacted with TFIIE alpha and with TFIIF alpha (RAP74) but not with TFIIB, TFIIE beta, or TFIIF beta (RAP30). Further studies with TAFII80 mutations revealed three distinct interaction domains which fall within regions conserved in human TAFII80, Drosophila TAFII60, and yeast TAFII60. The N terminus of TAFII80 (residues 1-100) interacts with both TAFII31 and TAFII20, while two C-terminal regions are involved, respectively, in interactions with TAFII250 and TFIIF alpha (RAP74) (residues 203-276) and with TBP and TFIIE alpha (residues 377-505). The interactions between TAFII80 and general factors TFIIE alpha and TFIIF alpha (RAP74) could be important for recruitment of GTFs during activator-dependent transcription. Because TAFs 80, 31, and 20 show sequence similarities to histones H4, H3, and H2B, as well as some parallel interactions, this subset of TAFs may form a related core structure within TFIID.

Amino Acid Sequence↗
PubMed1995

Sandwich immunoassay specific for the N-terminal sequence of osteocalcin.

A monoclonal antibody (10B) against the N-terminal sequence of human osteocalcin was selected to characterize its epitope and species specificity. The cross-reactivity of 10B with human and rat osteocalcin demonstrated that the reactivities of 10B with both human and rat osteocalcins were very similar. The pin technology method was used to determine the epitope and clearly demonstrated that the epitope recognized by 10B was localized to residues 12-16, the sequence of which is identical in rat and human osteocalcin molecules. This monoclonal antibody was found to be useful for designing region-specific sandwich immunoassay systems for human and rat N-terminal osteocalcin (N-OC) molecules using rabbit anti-hN20 and anti-rN20 polyclonal antibodies, respectively. The osteocalcin levels in serum determined by this N-OC method were stable during prolonged storage at 25 degrees C and the method could be usefully applied in the development of immunoassay systems for many osteocalcin molecules from many other species.

Amino Acid Sequence↗
PubMed1995

Genetic association between chromosome 8 microsatellite (MS8-134) and Werner syndrome (WRN): chromosome microdissection and homozygosity mapping.

Werner syndrome (WRN) is an autosomal recessive disorder characterized by premature aging that has been mapped to the short arm of chromosome 8, 8p11.2-p12. To refine the genetic map around the WRN region, we have isolated eight microsatellites for this region from a microdissection library. We typed members of Japanese families with WRN on the basis of homozygosity mapping analysis. There was no obligate recombination between the WRN locus and microsatellite clone, MS8-134 (D8S1055). The maximum lod score was 20.28 at theta = 0.00. Alleles for MS8-134 showed association with WRN in a case-control study (OR = 3.55, 95% CI 1.56-8.07, P < 0.01). Such microsatellites from a microdissection library of the definite chromosome region may be useful for positional cloning of the WRN gene.

Base Sequence↗
PubMed1995

Cloning of a cDNA for DNA supercoiling factor reveals a distinctive Ca(2+)-binding protein.

DNA supercoiling factor is a protein capable of generating negative supercoils into a relaxed DNA in conjunction with eukaryotic DNA topoisomerase II. A cDNA clone encoding the Bombyx mori supercoiling factor has been isolated and characterized. The cDNA sequence contains an open reading frame of 322 amino acids rich in acidic residues. A local region of the predicted polypeptide shares a weak homology with the central portion of bacterial DNA gyrase A subunit. The cDNA sequence also predicts two direct repeats within the factor. Each repeat unit consists of a potential EF-hand domain. The factor contains three other potential EF-hand domains and actually binds Ca2+. Moreover, the supercoiling reaction has been shown to be activated by Ca2+. These results implicate Ca2+ in the control of the superhelical state of DNA.

Amino Acid Sequence↗
PubMed1995

Characterization of subspecies of lipoprotein containing apolipoprotein A-I in heterozygotes for familial lecithin:cholesterol acyltransferase deficiency.

We characterized two species of lipoproteins containing apo A-I, one containing only apo A-I (LpA-I) and the other containing both apo A-I and apo A-II (LpA-I/A-II), in three heterozygotes for familial lecithin:cholesterol acyltransferase deficiency (LCAT). In these patients, particle size and the chemical composition of LpA-I differed from those in normal controls. Small particles < 8.8 nm in diameter were predominant, and protein content was higher in patients' LpA-I than that in normal LpA-I. Changes in LpA-I/A-II were mostly quantitative. Percent lipid and protein composition in LpA-I/A-II were similar to those in normal controls. Despite low LCAT mass and activity in the heterozygotes, the molar and fractional rate of cholesterol esterification in their LpA-I and LpA-I/A-II particles were similar to, or higher than, that of normal controls. We conclude that: (i) low LCAT mass and activity is the likely cause of the quantitative and qualitative differences in LpA-I in heterozygotes; and (ii) a deficiency of normal LpA-I particles 11.1 nm in diameter and the existence of small particles < 8.8 nm in diameter may be responsible for the normal, or higher than normal, cholesterol esterification rate of LpA-I and LpA-I/A-II in heterozygotes.

Adult↗
PubMed1995

Human ribosomal RNA gene cluster: identification of the proximal end containing a novel tandem repeat sequence.

Human ribosomal RNA genes (rDNA) are arranged as tandem repeat clusters on the short arms of five pairs of acrocentric chromosomes. We have demonstrated that a majority of the rDNA clusters are detected as 3-Mb DNA fragments when released from human genomic DNA by EcoRV digestion. This indicated the absence of the EcoRV restriction site within the rDNA clusters. We then screened for rDNA-positive cosmid clones using a chromosome 22-specific cosmid library that was constructed from MboI partial digests of the flow-sorted chromosomes. Three hundred twenty rDNA-positive clones negative for the previously reported distal flanking sequence (pACR1) were chosen and subjected to EcoRV digestion. Seven clones susceptible to EcoRV were further characterized as candidate clones that might have been derived from the junctions of the 3-Mb rDNA cluster. We identified one clone containing part of the rDNA unit sequence and a novel flanking sequence. Detailed analysis of this unique clone revealed that the coding region of the last rRNA gene located at the proximal end of the cluster is interrupted with a novel sequence of approximately 147 bp that is tandemly repeated and is connected with an intervening 68-bp unique sequence. This junction sequence was readily amplified from chromosomes 21 and 15 as well as 22 using the polymerase chain reaction. Fluorescence in situ hybridization further indicated that the approximately 147-bp sequence repeat is commonly distributed among all the acrocentric short arms.

Animals↗
PubMed1995

ATP-evoked membrane current in guinea pig adrenal chromaffin cells.

Adenosine 5'-triphosphate (ATP) evoked an inward current in whole-cell voltage-clamped adrenal chromaffin cells of the guinea pig. The reversal potential (Erev) of ATP-evoked current was about 0 mV in normal external solution and was shifted towards negative potentials by substituting Tris+ or sucrose, but not Ca2+, for the extracellular Na+. This current was mediated by the activation of non-selective cation channels and had some different properties from nicotinic current. It is suggested that these channels may function as a part of the ATP-induced Ca2+ influx pathway in guinea pig chromaffin cells.

Adenosine Triphosphate↗
PubMed1995

Isolation and the gene cloning of an alkaline shock protein in methicillin resistant Staphylococcus aureus.

The growth of Staphylococcus aureus occurs at a wide range of pH(5-10), while the optimal is pH 7.0-7.5. The molecular mechanism of such pH tolerant properties should be elucidated because the production of the virulence factors was greatly affected by environmental pH. The effect of pH shift on the composition of cytosolic proteins in S. aureus was examined. A protein with a molecular mass of 23 kDa was remarkably enhanced by a pH upshift from 7 to 10. This alkaline shock protein (ASP23) was isolated and purified by ion-exchange chromatography. The N-terminal sequences of the purified protein and the protease-digested peptides were analyzed. The 320-bp DNA fragment that was designed from the peptide analysis was amplified. Using the amplified fragment as a probe, the ASP gene, asp23, was cloned. The deduced primary sequence of ASP23 comprised 169 amino acids with a calculated molecular weight of 19,191. Northern analysis revealed that asp23 was positively regulated at the transcription level by alkaline shock. Homology search revealed that asp23 is a novel gene. Although the physiological role of ASP23 has yet to be further analysed, we suggest that ASP23 plays a key role in alkaline pH tolerance of S. aureus.

Amino Acid Sequence↗
PubMed1995

Cooperatively between an upstream TATA-like sequence and a CAA repeated element mediates E1A-dependent negative repression of the H-2Kb class I gene.

In primary rodent cells transformed by the E1A region of the highly oncogenic adenovirus type 12, repression of transcription mediated by the far upstream TATA-like element was observed only in conjunction with either possible juxtaposition of a CAA repeated element in the presence of E1A and was dependent upon the relative arrangement of both the TATA-like and CAA repeated motifs in both homologous and heterologous promoter constructs. A gel shift competition study demonstrated that the TATA-binding protein (TBP) or a TBP-like protein can bind to both the upstream TATA-like sequence and the regular TATA box on the H-2Kb basal promoter. Moreover, employing immunoselection and cyclic amplification and selection of targets (CASTing) methods with nuclear extracts derived from Ad12-E1A transformants, we have identified a high affinity binding site in the H-2Kb class I promoter for E1A-associated DNA-binding proteins. The sequences of the binding sites were identified and were found to contain both the upstream TATA-like motif and the CAA repeated motifs. Our results suggest that the TATA-like sequence in the far upstream region of the H-2Kb gene is one of the elements that is required for Ad12-E1A-mediated negative repression.

Adenovirus E1A Proteins↗
PubMed1995

Stability and pharmacokinetic studies of a new immunosuppressant, mycophenolate mofetil (RS-61443), in rats.

Mycophenolate mofetil (MPM), a new immunosuppressant, is a morpholinoethyl ester of mycophenolic acid (MPA). The enzymatic and non-enzymatic hydrolysis was studied in an artificial digestive fluid, rat plasma, and tissue homogenates. MPM was chemically stable in the artificial digestive fluid. In rat tissue homogenates and plasma, MPM was rapidly hydrolysed to MPA. The conversion rate of MPM to MPA in various rat tissue homogenates was in the order of liver > kidney > plasma > small-intestine epithelial cells. After the intravenous injection of MPM at 16.7 mg kg-1, the terminal elimination half-life, t1/2 beta, was 4.74 +/- 0.33 (mean +/- SD)h, and the area under the plasma concentration versus time curve, AUC, was 48.78 +/- 6.01 micrograms h mL-1. After intraduodenal (ID) administration of MPM at 16.7 mg kg-1, t1/2 beta was 3.92 +/- 1.05 h, and the AUC was 38.08 +/- 8.30 micrograms h mL-1. The systemic availability of MPA after ID MPM dosing was 1.52 times higher than that after ID administration of MPA. This result supports the usefulness of MPM as an oral prodrug of MPA as a new oral immunosuppressant.

Animals↗
PubMed1995

Synonymous and nonsynonymous substitutions in mammalian genes and the nearly neutral theory.

The nearly neutral theory of molecular evolution predicts larger generation-time effects for synonymous than for nonsynonymous substitutions. This prediction is tested using the sequences of 49 single-copy genes by calculating the average and variance of synonymous and nonsynonymous substitutions in mammalian star phylogenies (rodentia, artiodactyla, and primates). The average pattern of the 49 genes supports the prediction of the nearly neutral theory, with some notable exceptions. The nearly neutral theory also predicts that the variance of the evolutionary rate is larger than the value predicted by the completely neutral theory. This prediction is tested by examining the dispersion index (ratio of the variance to the mean), which is positively correlated with the average substitution number. After weighting by the lineage effects, this correlation almost disappears for nonsynonymous substitutions, but not quite so for synonymous substitutions. After weighting, the dispersion indices of both synonymous and nonsynonymous substitutions still exceed values expected under the simple Poisson process. The results indicate that both the systematic bias in evolutionary rate among the lineages and the episodic type of rate variation are contributing to the large variance. The former is more significant to synonymous substitutions than to nonsynonymous substitutions. Isochore evolution may be similar to synonymous substitutions. The rate and pattern found here are consistent with the nearly neutral theory, such that the relative contributions of drift and selection differ between the two types of substitutions. The results are also consistent with Gillespie's episodic selection theory.

Animals↗
PubMed1995

Gene conversion vs point mutation in generating variability at the antigen recognition site of major histocompatibility complex loci.

In order to assess the roles of gene conversion followed by natural selection and balancing selection for point mutations in polymorphisms at major histocompatibility complex (MHC) loci, DNA sequences of several mammalian taxa were analyzed. Synonymous and nonsynonymous diversities were estimated separately for the antigen recognition site (ARS) and the remaining region of class I and class II genes. In some sequence pairs, the number of nonsynonymous substitutions exceeds that of synonymous substitutions at the ARS. This result indicates that some kind of balancing selection for point mutation is operating. In other sequence pairs (particularly of bovine and of rabbit), the number of synonymous substitutions at the ARS exceeds the same number at the remaining region. This result indicates that gene conversion involving a short region followed by natural selection is important. In general, a combination of gene conversion, point mutation, natural selection and random drift is thought to have contributed to polymorphisms.

Animals↗
PubMed1995

Variation in synonymous substitution rates among mammalian genes and the correlation between synonymous and nonsynonymous divergences.

Using mammalian gene sequences, the variances in the numbers of synonymous and nonsynonymous substitutions among genes were estimated together with the correlation coefficient between the two. The expected correlation coefficient can be obtained under the neutral theory using these estimated values of the variances. The expected coefficient is found to often be one-half to two-thirds of the observed value. Possible causes for the disagreement were discussed, such as correlated selective constraints on the two types of substitutions and excess doublet mutations. The variance of mutation rate and that of selective constraint were also estimated. The results show that the coefficient of variation of the former is 0.2-0.3, whereas that of the latter is 0.7-0.9.

Animals↗