Search PubMed⌕ Search

Biomedical subjects

T Mukai

Publications and source records attributed to T Mukai.

At least 379 records · Page 21Linked to original sources
PubMed1980

Differences in contractile responses to acetylcholine and serotonin in rat stomach fundus strips.

The differences in contractile responses to acetylcholine (ACh) and serotonin (5-HT) were studied in the rat fundus strips. At low temperatures, the contractile response to 5-HT was reduced more noticeably than to ACh. The contraction induced by ACh at 4 degrees C was not inhibited by La3+. Removal of extracellular Ca2+ reduced the response to 5-HT more significantly than that to ACh.. La3+, verapamil and D-600 inhibited the 5-HT response more than the ACh response. In Ca2+-free solution the contractile response to ACh of a fundus strip preloaded with Ca2+ was lar ger than that to 5-HT. These results suggest that the Ca2+ movements induced by ACh and by 5-HT are different, and that the difference in Ca2+ movements may cause the difference in contractile responses to the two agonists at low temperatures.

Acetylcholine↗
PubMed1980

Selection of viability at loci controlling protein polymorphisms in Drosophila melanogaster is very weak at most.

In an isolated Drosophila population the frequency of chromsomes carrying the second chromosome inversion In(2L)t is about 60%. Three isozyme loci are nearly monomorphic in the inversion-carrying chromosomes but are highly polymorphic in other chromosomes. From known recombination frequencies and the slight polymorphism, it is estimated that the inversion-carrying chromosomes are descended from one or a few identical chromosomes introduced about 1000 generations previously. This is long enougn for lethal and mildly deleterious mutants to reach equilibrium frequencies but not long enough for very weakly selected mutants. Because the difference in viability between homozygous and heterozygous chromosomes is the same, it is inferred that there is at most very weak selection of isozyme loci. This method is sensitive enough to detect selective differences of 0.0005 per locus or less.

Animals↗
PubMed1980

Linkage disequilibrium in isolated populations of Drosophila melanogaster.

In order to test the interaction effect of overdominance and random genetic drift on the formation of linkage disequilibria under the condition of multiplicative gene action, linkage disequilibria between isozyme genes, inter se, and between polymorphic inversions and isozyme genes were tested for the second chromosomes of Drosophila melanogaster sampled from two isolated Pacific islands and one locality of the northern district of the mainlands of Japan. The effective sizes of these populations were known to be approximately 3,000 to 6,000 on the basis of the allelism rate of lethal chromosomes and their frequencies. The following results were obtained: (1) No linkage disequilibrium considered to be induced by epistasis, including the interaction between overdominance and random genetic drift, was detected. (2) Nonrandom association between polymorphic inversions and isozyme genes that are included in the inversions or located in the adjacent region outside the inversions was detected. (3) On the basis of the comparison of chi (2) values, indicating the magnitudes of linkage disequilibrium, between the present isolated populations and the Raleigh, N.C., population (Mukai et al. 1974, 1977), the characteristics of the isolated populations and the nature of these linkage disequilibria are discussed.

Animals↗
PubMed1980

Test for selection on polymorphic isozyme genes using the population cage method.

Published experimental data of several species of Drosophila using the population cage method were reexamined. The authors of these works have claimed that selection operates on polymorphic isozyme genes. Since selection coefficients (s) estimated by us for the above data, assuming overdominance, or for some cases, additivity between alleles, were too large (s greater than 0.1), we conclude that these experimental results do not reflect the effects of the single loci in question; rather, we suggest that careful experimentation and judgment are required for testing with the population cage method whether or not selection actually operates on single genes.

Animals↗
PubMed1980

[Emission CT].

Explore the source record for details and available documents.

Carcinoma, Hepatocellular↗
PubMed1979

Lack of experimental evidence for frequency-dependent selection at the alcohol dehydrogenase locus in Drosophila melanogaster.

Two experiments were conducted for testing frequency-dependent selection at the alcohol dehydrogenase locus (Adh; map position, 2--50.1), where two types of alleles, AdhF and AdhS, have been found to be polymorphic in natural populations. First, a competition experiment was carried out between inversion-free AdhF/AdhF and AdhS/AdhS genotypes at five gene frequency levels (those of AdhF = 0.83, 0.67, 0.5, 0.33, and 0.17). First-instar larvae of the two homozygous types in various ratios were placed in a vial, and the frequency of adult flies of each genotype was determined. However, the relative viabilities of these two types did not change with the change in the frequencies of genotypes or genes. The second test was performed by using the results of viability tests with the Cy method of Wallace, using the results of inversion-free crosses only. Although there was variation in the gene frequencies among the vials in testing the viability of individuals consistng of random combinations of two second chromosomes, no difference was found in average viabilities among the vials in which the gene frequencies were different. Thus, no evidence for frequency-dependent selection was obtained.

Alcohol Oxidoreductases↗
PubMed1978

Purification and properties of deoxyribonuclease from human urine.

The DNAase in human urine was purified about 30-fold with a recovery of 28%. This involved DEAE-cellulose and phosphocellulose chromatography steps and gel filtration on Sephadex G-75. The enzyme required divalent cations such as Co2+, Mg2+, Mn2+ and Zn2+ for activity, but Ca2+, Cu2+ and Fe2+ were ineffective. EDTA and G-actin inhibited the reaction. The maximum activity was observed at pH 5.5 in acetate buffer plus Co2+ or Mg2+ and Ca2+. It had a molecular weight of approximately 38 000, estimated by gel filtration on Sephadex G-75 and isoelectric point of around pH 3.9. The enzyme is an endonuclease which hydrolyzes native, double-stranded DNA about 3 to 4 times faster than thermally denatured DNA to produce 5'-phosphoryl- and 3'-hydroxyl-terminated oligonucleotides. The final preparation was free of non-specific acid and alkaline phosphatases, phosphodiesterase and ribonuclease activities.

Chromatography, Gel↗
PubMed1978

Isolation and characterization of a plaque-forming lambda bacteriophage carrying a ColE1 plasmid.

A plaque-forming lambdaimm434 bacteriophage carrying the entire genome of colicinogenic factor E1 has been isolated and characterized. This phage, lambdaimm434ColE1, can lysogenize as a stable plasmid within a recombination-deficient Escherichia coli cell that lacks the normal attachment site for lambda phage. Furthermore, it has been found that lambdaimm434ColE1 phage carrying amber mutations in the O and P genes of the lambda genome, i.e., lambdaimm434OamPamColE1, behaves as a plaque-forming phage, and this finding suggests that the ColE1 factor DNA permits replication of the DNA of the plaque-forming phage.

Bacteriocin Plasmids↗
PubMed1978

[An evaluation of inhalation and perfusion scintigraphy with 81mKr (author's transl)].

As 81mKr is a radioactive noble gas which has a very short half-life of 13 seconds, it leads no environmental contamination in a laboratory room. Because of its low radiation dose in the human body, it had many merits in routine tests of the inhalation and perfusion scintigraphy, which were very useful extremely in infants, old men and severe patients in need of cooperation. The studies with 81mKr were, either, useful as a load test, since these could repeatedly readily, evaluate the ventilation and perfusion dynamics before and after administration of drugs and show the distribution of the ventilation and perfusion correspond to the various lung volume level.

Aged↗
PubMed1978

Quantitative assessment of ventilation-perfusion mismatch by radioxenon imaging of the lung.

By the use of xenon-133 and a scintillation camera with digital data storage and processing system, a topographic relationship between ventilation distribution (V) and perfusion distribution (Q) was examined quantitatively in two groups of normal nonsmokers and one of older smokers, all healthy. In addition, subjects with a variety of cardiopulmonary disease were tested. The fractional regional ventilation (VR) and regional perfusion (QR) were plotted against the V/Q ratio on a logarithmic abscissa for the normal subjects; both were distributed log-normally with a narrow standard deviation, and were dissociated slightly from each other. However, with smoking and with increasing age, the s.d. and the dissociation became wider, suggesting an impairment of gas exchange as estimated by alveolar-atrial gas-pressure differences (A-aD), which were calculated by putting these topographic relationships into a gas-exchange program in a computer. In various cardiopulmonary diseases a good correlation was found between the estimated A-aDO2 thus obtained and the actual A-aDO2 derived from analysis of the blood gases.

Adult↗