[CT evaluation of postsurgical patients in lung cancer].
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Humans↗
Biomedical subjects
T Ohta
Publications and source records attributed to T Ohta.
[Early and midterm results of valve replacement with the Björk-Shiley convexo-concave valve].
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Adolescent↗
[Echocardiographic assessment of the diameter of the aortic annulus].
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Aortic Valve↗
Two types of tRNA(Gm)methylase found in extreme thermophile, Thermus thermophilus strains HB 8 and HB 27.
There are two distinct strains HB 8 and HB 27 in an extreme thermophile, Thermus thermophilus, and both strains have their own tRNA(Gm)methylases, which specifically methylates the 2'-OH of the ribose ring in the D loop of tRNA. The Gm-methylases are very similar with respect to the recognition mechanism of substrate tRNA and the molecular weight, but differ in the temperature dependency of the enzyme activity. Gm-methylase from strain HB 8 possesses its activity even at low temperature (40 degrees C), whereas that of strain HB 27 shows very low activity at the temperature and increases the activity as the incubation temperature is raised. Amino acid compositions of both the enzymes are very similar except for Glx and Asx, but the content of secondary structure is very different as judged by circular dichroism.
Circular Dichroism↗
Characterization of apolipoprotein A-IV complexes and A-IV isoforms in human lymph and plasma lipoproteins.
We have isolated and characterised A-IV apolipoprotein (apo-A-IV) from human lymph and plasma by immunoabsorbance chromatography and two-dimensional electrophoresis. Two different apo-A-IV-containing lipoproteins were isolated from four different sources, human lymph triglyceride-rich fraction (TRL), lymph lipoprotein-deficient fraction (LDF), plasma high-density lipoprotein (HDL), and plasma lipoprotein-deficient fraction (LDF). The lipoprotein complexes obtained from lymph TRL and plasma HDL were similar and contained apo-A-IV, apo-A-I, and small molecular weight peptides (apo-C or -A-II). The second lipoprotein complex was isolated from lymph LDF and plasma LDF, and contained apo-A-IV, apo-A-I, and a peptide of Mr = 59,000. The lipid composition of the lipoprotein complexes varied according to the source: triglyceride predominating in lymph TRL and phospholipid and cholesteryl ester from the other sources. Free cholesterol was conspicuously present in very small amounts. Using two-dimensional electrophoresis and immunoblotting techniques, eleven isoproteins of apo-A-IV were identified (pI-4.98, 5.06, 5.10, 5.15, 5.20, 5.22, 5.25, 5.30, 5.34, 5.42, and 5.48). The isoprotein pattern of lymph TRL and plasma HDL was similar, but that of lymph and plasma LDF were different patterns. These results suggest that apo-A-IV associated with d less than 1.21 lipoproteins and apo-A-IV present in LDF may be in metabolically separate lipoproteins and may have different physiological roles.
Amino Acids↗
L-Lactate dehydrogenase from Thermus caldophilus GK24, an extremely thermophilic bacterium. Desensitization to fructose 1,6-bisphosphate in the activated state by arginine-specific chemical modification and the N-terminal amino acid sequence.
Heat-stable and fructose-1,6-bisphosphate-activated L-lactate dehydrogenase (EC 1.1.1.27) has been purified from an extremely thermophilic bacterium, Thermus caldophilus GK24 [Taguchi, H., Yamashita, M., Matsuzawa, H. and Ohta, T. (1982) J. Biochem. (Tokyo) 91, 1343-1348]. N-terminal sequence analysis of the first 34 amino acids of the enzyme indicates that the N-terminal arm region (first 1-20 residues) known for the vertebrate L-lactate dehydrogenases is completely missing in the T. caldophilus enzyme, while there is a high homology of sequence between the regions which are considered to be part of the NAD-binding domain. The C-terminal amino acid of the enzyme was phenylalanine. Analysis of the amino acid composition showed that T. caldophilus enzyme contained much more arginine and fewer lysine than other bacterial and vertebrate L-lactate dehydrogenases. On modification reaction with 2,3-butanedione in the presence of NADH and oxamate, an enhanced activity of the T. caldophilus L-lactate dehydrogenase was obtained independently of fructose 1,6-bisphosphate, and the modified enzyme was desensitized to fructose 1,6-bisphosphate. Amino acid analysis indicated that such a desensitization in the active state was caused by the modification of only one arginine residue per the enzyme subunit. Desensitization of the enzyme was inhibited in the presence of fructose 1,6-bisphosphate. A similar desensitization was observed using 1,2-cyclohexanedione instead of 2,3-butanedione. The enzyme was irreversibly modified with 2,3-butanedione and characterized. The irreversibly modified enzyme also showed an enhanced activity independently of fructose 1,6-bisphosphate, and its pyruvate saturation curve was similar to that of the native enzyme measured in the presence of fructose 1,6-bisphosphate. Fructose 1,6-bisphosphate, which increases the thermostability of the native enzyme, did not affect that of the modified enzyme, while thermostability of the modified enzyme slightly decreased. Amino acid analysis indicated that only the arginine content was decreased by the modification. These results show that arginine residue(s) exist in the binding site for fructose 1,6-bisphosphate on the enzyme, and that the arginine residue(s) play some important role in the allosteric regulation of the enzyme activity.
Allosteric Regulation↗
Immunohistochemical localization of Na+, K+-ATPase in the choroid plexus.
To determine if canine and rat choroid plexus Na+,K+-ATPase can be localized by immunoperoxidase staining after fixation and embedding, we prepared rabbit antiserum to purified canine kidney medulla Na+,K+-ATPase. When sodium dodecylsulfate polyacrylamide electrophoretic gels of purified canine kidney Na+,K+-ATPase and canine kidney microsomes were treated with antiserum followed by [125I]protein A and autoradiography, the canine microsomes and purified Na+,K+-ATPase showed a prominent radioactive band coincident with the alpha-, beta- and gamma-subunits of the purified canine kidney enzyme. When the rabbit immunoglobulin that was purified from the Na+,K+-ATPase antiserum through DEAE-cellulose ion exchange chromatography was used for immunoperoxidase staining of the choroid plexus fixed with Bouin's fixative, intense immunoreactive staining was present on the epithelial cells of both choroid plexuses but was not found in the tissue around the vessel. The staining was especially confined to apical surfaces of the epithelial cells. The same procedure was performed in the canine kidney, and immunostaining was obtained in the tubules where Baskin and Stahl described the enzyme localization. No staining was seen with pre-immune serum of the normal rabbit. We concluded that both the canine and rat choroid plexus are rich in Na+,K+-ATPase, which plays an important role in cerebrospinal fluid (CSF) secretion.
Animals↗
Population genetics theory of concerted evolution and its application to the immunoglobulin V gene tree.
The previous simple model for treating concerted evolution of multigene families has been revised to be compatible with various new observations on the immunoglobulin variable region family and other families. In the previous model, gene conversion and unequal crossing-over were considered, and it was assumed that genes are randomly arranged on the chromosome; neither subdivision nor correlation of gene identity and chromosomal distance were considered. Although this model satisfactorily explains the observed amino acid diversity within and between species, it fails to predict the very ancient branching of the mouse immunoglobulin heavy chain V-gene family. By incorporating subdivided structure and genetic correlation with chromosomal distance into the simple model, the date of divergence may be satisfactorily explained, as well as the rate of nucleotide substitution and the amino acid diversity. The rate at which a V-gene is duplicated or deleted by conversion or by unequal crossing-over is estimated by the new model to be on the order of 10(-6) per year. The model may be applicable to other multigene families, such as those coding for silkmoth chorion or mammalian kallikrein.
Animals↗
Body surface isopotential maps in old anterior myocardial infarction undetectable by 12-lead electrocardiograms.
Body surface isopotential maps were recorded in 30 normal subjects and 32 patients with clinical evidence of old anterior myocardial infarction but without ECG findings of infarction. Position of the minimum in maps was compared at 5 msec intervals from the onset of QRS between the normal and infarction groups. A significant difference in the mean position of the minimum was observed at 5, 10, 15, 20, and 25 msec (p less than 0.001). The minima for the two groups achieved their clearest separation at 15 msec. Twenty-six of the 32 infarction patients showed the minima on the anterior chest, but 29 of the 30 normal subjects showed the minima on the back. These findings suggest the highly specific usefulness of body surface maps for the diagnosis of the presence of old anterior infarction undetectable by 12-lead ECGs.
Adult↗
Body surface isopotential maps in old inferior myocardial infarction undetectable by 12 lead electrocardiogram.
The purpose of this study is to examine the value of body surface isopotential maps in the diagnosis of old inferior myocardial infarction that can not be diagnosed by 12 lead ECG. Forty-three patients with a Q wave of at least 0.02 sec but less than 0.04 sec in width and also less than 25% of the R wave in depth in lead a VF of the 12 lead ECG were selected for this study. The patients were divided into infarction and noninfarction groups based on their clinical histories and cardiac catheterization data. The infarction group showed characteristic surface maps with a minimum which moved from the left posterior chest to the lower back or from the lower back to the right anterior lower chest in the early phase of QRS. The noninfarction group exhibited a minimum which shifted from the back to the right upper chest or from the left anterior chest to the lower back in the same phase. Thus, both groups were clearly distinguishable from each other by the positional change of the minimum in the early phase of QRS. This study suggested that body surface maps contain diagnostic information concerning the presence or absence of inferior myocardial infarction which is not easily available from the 12 lead ECG.
Adult↗
Some models of gene conversion for treating the evolution of multigene families.
A simple model of gene conversion presented earlier has been compared with a more general model under the assumption of no bias. The former is based on a simple concept that, by conversion, a gene (or a segment of a gene) is transferred from one locus to another in a multigene family. Intrachromatid symmetric conversion may result in reciprocal exchange of genes within a multigene family, and the previous theory of identity coefficients needs modification when it occurs. The relationship of various parameters of the two models was made clear in formulating the transition equations of identity coefficients. As an example of extending the analyses, a model of preferential conversion that is relevant to the observed uneven polymorphisms of class I genes in the major histocompatibility complex has been investigated. It differs from the biased conversion, in that directional process is through location of genes on the chromosome. It is shown that the model satisfactorily explains the observed data, even though the effect of preferential conversion is difficult to distinguish from that of natural selection.
Biological Evolution↗
The cohesive population genetics of molecular drive.
The long-term population genetics of multigene families is influenced by several biased and unbiased mechanisms of nonreciprocal exchanges (gene conversion, unequal exchanges, transposition) between member genes, often distributed on several chromosomes. These mechanisms cause fluctuations in the copy number of variant genes in an individual and lead to a gradual replacement of an original family of n genes (A) in N number of individuals by a variant gene (a). The process for spreading a variant gene through a family and through a population is called molecular drive. Consideration of the known slow rates of nonreciprocal exchanges predicts that the population variance in the copy number of gene a per individual is small at any given generation during molecular drive. Genotypes at a given generation are expected only to range over a small section of all possible genotypes from one extreme (n number of A) to the other (n number of a). A theory is developed for estimating the size of the population variance by using the concept of identity coefficients. In particular, the variance in the course of spreading of a single mutant gene of a multigene family was investigated in detail, and the theory of identity coefficients at the state of steady decay of genetic variability proved to be useful. Monte Carlo simulations and numerical analysis based on realistic rates of exchange in families of known size reveal the correctness of the theoretical prediction and also assess the effect of bias in turnover. The population dynamics of molecular drive in gradually increasing the mean copy number of a variant gene without the generation of a large variance (population cohesion) is of significance regarding potential interactions between natural selection and molecular drive.
Biological Evolution↗
Population genetics of transposable elements.
Transposable elements are DNA sequences that can move or duplicatively transpose on the chromosome. A simple model of transposable elements was studied, and the frequency spectrum, allelism, and identity coefficients at equilibrium were obtained. In the analyses, the two cases of asexual haploid with no recombination and diploid with free recombination were treated separately. It was shown that the multiple allele theory of population genetics is applicable to the problems of frequency spectrum and allelism. On the other hand, identity coefficients may be formulated analogously to the treatment of concerted evolution of multigene families. Results indicate that, except for allelic identity, the model of transposable elements and that of multigene families predict similar values of identity coefficients.
Biometry↗
Selective utilization of 2-thioribothymidine- and ribothymidine-containing tRNAs by the protein synthetic systems of Thermus thermophilus HB 8 depending on the environmental temperature.
An extreme thermophile, Thermus thermophilus HB 8, contains two types of tRNAs, T- and S2T-containing tRNAs. Their relative content changes depend on the growth temperature of the bacterial cells (1-3). To elucidate the reason why the extreme thermophile possesses the two types of tRNAs, an attempt was made to clarify how these tRNAs are utilized in in vivo protein synthetic systems of the bacteria cultured at different temperatures. First, a method was developed to isolate active polysomes from the thermophile cells cultured at 55 degrees C, 65 degrees C, and 77 degrees C. Then, tRNAs were separated from the polysomes and the T- and S2T-contents of the tRNAs were determined by HPLC. The relative content of S2T-tRNAs in the polysomes from 77 degrees C cells was much higher than that in bulk tRNAs from whole cells cultured at the same temperature, but the situation was reversed in 50 degrees C cells. These results clearly show that the protein synthetic systems of the thermophile have some selection mechanism to utilize either T- or S2T-containing tRNAs preferentially depending on the environmental temperature.
Bacterial Proteins↗
Escherichia coli K-12 tolZ mutants tolerant to colicins E2, E3, D, Ia, and Ib: defect in generation of the electrochemical proton gradient.
Spontaneous Escherichia coli K-12 mutants tolerant to colicin E3 were isolated, and on the basis of their tolerance patterns to 19 kinds of colicins, a new phenotypic class of tolZ mutants was found. The tolZ gene was located between min 77 and 78 on the E. coli K-12 genetic map. The tolZ mutants were tolerant to colicins E2, E3, D, Ia, and Ib, and showed an increased sensitivity to ampicillin, neomycin, and EDTA, but not to deoxycholate; they were able to grow on glucose minimal medium, but not on nonfermentable carbon sources (succinate, acetate, pyruvate, lactate, malate, etc.). The pleiotropic phenotype of the tolZ mutant was due to a single mutation. Both respiration and membrane ATPase activity of the tolZ mutant were normal. The tolZ mutant had a defect in the uptake of proline, glutamine, thiomethyl-beta-D-galactoside, and triphenylmethylphosphonium ion; these uptake systems are driven by an electrochemical proton gradient (delta-mu H+) or a membrane potential (delta psi). In contrast, the uptake of methionine and alpha-methyl-D-glucoside, which is not dependent on delta-mu H+ and delta psi, was normal in the tolZ mutant. Glucose 6-phosphate uptake at pH 5.5, which is driven by a transmembrane pH gradient, in the tolZ mutant was similar to the parent level. These results indicate that the tolZ mutant has a defect in the generation of delta-mu H+ and delta psi.
Ampicillin↗
Indirect blood pressure measurement at the common femoral artery.
In the present study the technique and the reliability of indirect blood pressure measurement at the common femoral level was described. The blood pressure was measured by using a long cuff, which encircled the hips at the level of the groin, and determining the flow signals by Doppler technique applied at the ankle. In order to transmit the cuff pressure to the artery, a slender bag with air, which was a blood pressure cuff used in children, was placed over the common femoral artery under the cuff. A 14 cm. wide cuff-bladder was usually used, but in obese subjects with the size of hips more than 90 cm, a 16 cm. wide cuff-bladder was applied. In patients with collateral vessels around the groin due to the iliac disease, the blood pressure could be measured by placing the Doppler flat probe over the common femoral artery or the collateral vessel. In observation of 24 subjects, a close correlation was obtained between the femoral cuff pressures and common femoral intra-arterial pressures. Furthermore, blood pressure values at the common femoral level measured indirectly showed similar reproducibility as those at the ankle and toe levels.
Arterial Occlusive Diseases↗
Optimal time for replacement surgery in chronic aortic valve disease.
The purpose of this study was to clarify the characteristic features of aortic valvular heart disease (VHD) compared with mitral VHD and to discuss the optimal time for replacement surgery. Serial echocardiographic studies on a medically treated group with aortic regurgitation disclosed that those patients presenting with congestive heart failure or dying during follow-up period showed the systolic dimension of the left ventricle (LVDs) over 55 mm and percentage fractional shortening (%FS) to be less than 27%. Factors influencing the result of replacement surgery for aortic regurgitation was studied by comparing the group in which the postoperative course was uneventful with the group in which postoperative support with catecholamine of the intra-aortic balloon pumping (IABP) was necessary. Systolic dimension of the left ventricle, %FS and mVcf by echocardiography were significantly different in the two groups. It is concluded from these results that aortic valve replacement for the aortic regurgitation should be performed just before, or immediately after, LVDs exceeds 50 mm, %FS falls below 28% and mVcf falls below 0.9, even in asymptomatic patients.
Aortic Valve↗
Body surface isopotential maps of normal Japanese children.
Body surface isopotential maps were compared between 52 normal children and 47 normal adults. While sequential changes in body surface potential distribution were similar, 4 significant differences in body surface maps were observed between them: 1) Surface maps of normal children showed less smooth contour of isopotential lines than did those of normal adults. For example, breakthrough minimum was recognized more frequently in children (100%) than adults (65%). 2) Breakthrough minimum appeared earlier in normal children (23.2 +/- 5.0 msec) than in normal adults (29.2 +/- 4.3 msec), and more leftwards on the chest. 3) Forty-seven percent of the children showed positive potentials on the upper and right portions of the anterior chest in the terminal phase of QRS, but this pattern was not observed in normal adults. 4) The maximum at the time of the peak of the T wave appeared more leftward in normal children than normal adults.
Adolescent↗