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Biomedical subjects

A Suyama

Publications and source records attributed to A Suyama.

At least 55 records · Page 3Linked to original sources
PubMed1992

Temperature-gradient DNA probe chromatography of nucleic acids on nonporous supports.

Temperature-gradient DNA probe chromatography of nucleic acids on a nonporous support with a homogeneous particle size of 2.5 microns showed a higher base sequence discriminating power and a larger linear capacity than that on a porous support with a larger and less homogeneous particle size. The resolution on the nonporous support was high enough to separate samples with a single-base mismatch of the less destabilizing groups, including G-G and G-T base mismatches, even when it locates very near the end of the probe.

Chromatography, Affinity↗
PubMed1991

Two types of linkage between codon usage and gene-expression levels.

The relation between codon usage and gene-expression levels is an intensively investigated and discussed topic in the field of molecular evolution. We statistically analyzed 25 Escherichia coli gene sequences by a new classification of synonymous codons and found that (i) there are two distinct types of linkage between codon usage and gene-expression levels in E. coli, and (ii) one of the two kinds of codon preferences (the codon preference concerned with interaction of GC/AT choice at three codon positions) is observed significantly in weakly expressed genes.

Base Sequence↗
PubMed1991

Phenomenological theory of GC/AT pressure on DNA base composition.

We present a phenomenological theory expressing the constraints operating on the (G + C) contents of the three codon positions, i.e., first, second, and third bases of codons, by using the smallest number of constraint parameters having clear physical and genetic meaning. Theoretical curves displaying base composition at each of the three codon sites are given. The agreement between the theoretical curves and the data points of 1277 genes is quite good irrespective of the species from which the DNAs originated; the curves might be universal ones and the constraint parameters might have general biological meanings in relation to the DNA/RNA and protein functions.

Base Composition↗
PubMed1990

A rapid and efficient cloning method with a solid-phase DNA probe: application for cloning the 5'-flanking region of the gene encoding human fibronectin.

A rapid and efficient gene-cloning method was developed using oligodeoxyribonucleotide probes (approx. 30-mer) immobilized by their 5' terminal to the gel (LiChrosphare Si1000; used for high-performance liquid chromatography). The method allowed us to concentrate DNA fragments having a particular base sequence in an eppendorf tube with very high efficiency within 2 h. For example, genomic DNA encoding the human fibronectin gene (fn) was concentrated by this method and cloned into lambda Charon4A vector. Screening of the concentrated genomic DNA library for the 5' region of the human fn gene showed that approx. 30% of 3000 recombinant phages tested were positive clones. Various factors affecting cloning efficiency were investigated.

Base Sequence↗
PubMed1989

Lack of effect of indomethacin and captopril on protein-induced glomerular hyperfiltration in normal subjects.

We examined the possible roles of renal prostaglandins, renin-angiotensin and the kallikrein-kinin system in protein-induced glomerular hyperfiltration in normal subjects. The normal subjects were divided into three groups, i.e., control, indomethacin-treated and captopril-treated groups. Protein loading (0.6 g/kg BW as protein) resulted in a significant increase in glomerular filtration rate (GFR) from a baseline of 98 +/- 8 ml/min/1.73 M2 to 135 +/- 13 (P less than 0.01) in the control group. In both the indomethacin and captopril groups, significant elevations of GFR were observed after the test meal. The urinary kallikrein excretions after the meal were not significantly different from those for preloading in all groups. These results suggest that renal prostaglandins, renin-angiotensin and the kallikrein-kinin system may be less involved in protein-induced glomerular hyperfiltration in normal subjects.

Adult↗
PubMed1989

Effect of renal prostaglandins on survival in patients with liver cirrhosis.

To assess the effect of renal prostaglandins on the prognosis of liver cirrhosis, we studied the relationship between the effect of prostaglandin synthetase inhibition by indomethacin on glomerular filtration rate (GFR) and effective renal plasma flow (RPF) and survival in 30 patients with liver cirrhosis. After indomethacin administration, GFR dropped significantly from 86 +/- 2 ml/min to 73 +/- 3 ml/min (p less than 0.01) and RPF from 421 +/- 10 to 349 +/- 14 ml/min (p less than 0.01). Survival was not correlated with baseline GFR or RPF, but was correlated with changes in both GFR and RPF after indomethacin administration (p less than 0.01). The cumulative survival rate from 1 to 7 yr was significantly higher (p less than 0.01) in patients with a decrease in GFR of less than or equal to 15% after indomethacin administration than in patients with a decrease in GFR of more than 15%. Findings for changes in RPF after indomethacin administration were similar. These results suggest that the augmentation of prostaglandin inhibition by indomethacin is associated with a poor prognosis of liver cirrhosis. It may be involved in the depletion of renal prostaglandins to maintain renal hemodynamics in patients with liver cirrhosis.

Female↗
PubMed1988

Vestiges of lost introns in the thermal stability map of DNA.

The absence of introns in prokaryotic genes has been explained by intron loss on various bases. Here we report another piece of evidence on intron loss, which was found in the thermal stability map of DNA. We calculated the local melting temperature of cDNA sequences and found that (i) gaps in thermal stability tend to occur near intron positions with a statistical significance, and (ii) one-third of the gaps far from intron positions can be assigned to lost introns. From these results we conclude that the gaps of thermal stability in protein coding regions are the vestiges of lost introns.

Animals↗
PubMed1988

Characteristic features of thermal stability map of DNA in Escherichia coli and eukaryotic genes.

Distribution of double-helix thermal stability of Escherichia coli and eukaryotic DNAs was analyzed. The results confirmed the previous propositions based on the study of the stability distribution in phage DNAs: (1) stability fluctuation appears near the boundaries of protein coding regions (PCRs) and non protein coding regions (NPCRs); (2) PCRs have less fluctuation than NPCRs. The present analysis also revealed that the local G + C content is lower in the beginning of PCRs of E. coli than the average G + C content of PCR and that deviations in the amino acid composition and the third letter usage PCRs are involved in the low G + C content; the biological meaning of this is discussed in relation to mRNA structure.

Base Composition↗
PubMed1988

Random exercise stress test in diagnosing effort angina.

To improve the performance of exercise stress testing in the diagnosis of effort angina while minimizing risks of serious complications, we evaluated an impulse response of ST changes, which is a transient ST response resulting from a hypothetical, strenuous-impulselike exercise, without actually imposing the strenuous load. To obtain the impulse response, subjects walked intermittently according to a computer-generated random binary sequence on a treadmill for 20 minutes (with a constant speed of 1.7 mph and a slope of 10%). We used Fourier transform for beat-to-beat changes in ST level and the binary sequence of exercise. We then determined the transfer function by taking the ratio of Fourier transformed ST level to exercise over the frequency range of 0.5 through 5.0 cycles/min. Converting the transfer function to the time domain yielded the impulse response of ST change. The subjects consisted of 49 patients (60 +/- 9 years) with effort angina, 13 patients with atypical chest pain (56 +/- 9 years), and 30 healthy, male volunteers (23 +/- 7 years). In 82 subjects (89%), the ST impulse response showed an initial depression followed by a smooth, gradual restoration toward the preexercise ST level (type I response). The average duration of the initial depression was 8 +/- 3 seconds in the healthy volunteers, whereas it was significantly prolonged to 23 +/- 14 seconds in effort angina (p less than 0.05). The depression in patients with atypical chest pain was not significantly different from that in the healthy volunteers.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1988

Prognostic significance of urinary neopterin levels in patients with hepatocellular carcinoma.

Urinary neopterin levels were measured by high-performance liquid chromatography in 15 patients with liver cirrhosis, 18 patients with hepatocellular carcinoma and 20 normal subjects. The mean levels of urinary neopterin in patients with hepatocellular carcinoma were significantly elevated (p less than 0.01) compared to those in cirrhotics and normal subjects, but did not significantly differ between cirrhotics and normal subjects. Urinary neopterin levels correlated significantly with tumor size in patients with hepatocellular carcinoma but not with serum alpha-fetoprotein. Hepatocellular carcinoma patients with high urinary neopterin levels appeared to have more serious hepatic dysfunction than those with normal urinary neopterin levels, and moreover, there was a significant difference (p less than 0.05) in survival between the two groups. These findings suggest that urinary neopterin excretion may be a good biochemical marker to assess the progression of tumor and a useful prognostic indicator in patients with hepatocellular carcinoma.

Biomarkers, Tumor↗
PubMed1988

Temperature gradient DNA-probe column chromatography: as tools for detection and purification of particular DNAs and RNAs.

We have developed the temperature-gradient DNA-probe column chromatography as the new method for detecting and purifying particular DNAs or RNAs accurately. The method has high discrimination resolution, and can detect a single-base change in sample base sequences. The method also has high performances in purification of particular DNAs or RNAs, which has been demonstrated by purification of bovine mitochondria serine t-RNA. None of other method can succeed in complete purification of this t-RNA molecule. The present method can be applied not only to molecular biology as basic tools for purifying and picking-up particular sequences but also to the medical field as diagnostic tools.

Base Sequence↗
PubMed1987

Yellow nail syndrome associated with chronic pericardial effusion.

A 74-year-old man had typical yellow nail syndrome, associated with pericardial effusion and hyperimmunoglobulinemia (IgG 3,179 mg/dl, IgM 402 mg/dl). A search of the literature fails to reveal a previously reported case of yellow nail syndrome associated with pericardial effusion.

Aged↗
PubMed1986

Prevalence of ventricular tachycardia in patients with different underlying heart diseases: a study by Holter ECG monitoring.

Twenty-four-hour Holter ECGs were recorded in 1089 patients. Ventricular tachycardia (VT) was observed in 184 tapes obtained from 81 patients (73 men and 8 women). Underlying heart diseases were present in 72 patients and no organic heart diseases were found in nine patients. The analysis of continuous 1-hour rhythm strips immediately before VT revealed that, in ischemic heart disease and hypertrophic cardiomyopathy, there was no correlation between the incidence of VT and the number or complexity of premature ventricular complexes (PVCs) within 1 hour before VT. In contrast, frequent or multiform PVCs were often observed during the pre-VT period in the patients with rheumatic heart disease or dilated cardiomyopathy. These findings suggest that the mechanism of VT may be different among the various underlying heart diseases. In addition, the mode of initiation of VT was evaluated. Only few episodes of VT occurred with the prematurity index value smaller than 1.0 or the vulnerability index value greater than 1.1. The correlation between the rate of VT and the preceding sinus rate was not significant, and the correlation between the rate of VT and the coupling interval of VT was weak. These facts suggest that the malignancy of VT, represented by the rate of VT, cannot be predicted by the preceding sinus rate or by the coupling interval of VT.

Adult↗
PubMed1986

A new method for DNA surface-property display and its application to E. coli promoter sequences.

A personal computer program to visualize and compare the property of double-stranded DNA surface has been developed. Comparison of the surface property between Watson-Crick base-pairs in B-form DNA has elucidated that the base-pair replacement between a "degenerated base-pairs" conserves the pattern of potential hydrogen-bonding sites in both major and minor grooves. The idea of the "degenerated base-pairs" was applied for the problem of the base-sequence variation from the consensus sequence in the -35 region of E. coli promoter. The sequence variation is found to have tendency to occur among the degenerated base-pairs.

Computer Graphics↗
PubMed1985

Gene expression in the polycistronic operons of Escherichia coli heat-labile toxin and cholera toxin: a new model of translational control.

A new model is proposed based on the suggestion that stable local secondary structures of mRNA interfere with ribosome movement on mRNA and consequently reduce the translation rate. This model accounts for a different level of translation for each cistron in the polycistronic mRNA of Escherichia coli heat-labile toxin (LT) and cholera toxin. We also conclude that the mRNA secondary structures have been conserved during the evolution of the toxin genes for its functional importance.

Bacterial Toxins↗
PubMed1985

Fine structure in the B-A transition of native DNA.

The B-A transition caused by high ethanol concentrations has been studied by the multi-dimensional spectrophotometer equipped with the computer-controlled microbullet. When ethanol concentration is increased, the CD signal at 270 nm of linearized ColEl DNA exhibits a biphasic transition; the first broad one and the second sharp one. The B-A transition of the ColEl DNA is much broader than that of alternative copolymers with shorter lengths. In addition, each PvuII restriction fragment of ColEl DNA has a different transition curve. Therefore the stability of the B-A transition varies along a long DNA molecule. The second transition is speculated to be caused by aggregation. When ethanol concentration is decreased, on the other hand, only a single transition shifted to lower ethanol concentration is observed. Thus the B-A transition curve has a hysteresis. A slow dissociation rate of the aggregation seems to cause the hysteresis.

Bacteriocin Plasmids↗