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Biomedical subjects

T Mukai

Publications and source records attributed to T Mukai.

At least 361 records · Page 20Linked to original sources
PubMed1981

Repeated DNA sequences near the 5'-end of the silk fibroin gene.

Four different repeated sequence elements have been found in cloned silk moth DNA, extending from 5700 base pairs upstream from the silk fibroin gene to 600 base pairs within its intervening sequence. Only 2 of the 12 overlapping restriction fragments examined, ranging from 164 to 1800 base pairs in length, do not contain a repeated sequence. The 830 base pairs adjoining the 5'-end of the fibroin gene hybridize with only one sequence in the Bombyx mori genome. Fibroin gene transcription initiates within this single-copy DNA at least 500 base pairs downstream from any repeated DNA sequence. The data show that repeated sequences comprise a major portion of the DNA flanking this developmentally regulated gene but not the DNA immediately 5' to it; that an intervening sequence can contain a repeated element; and that repeated sequences can be interspersed with one another as well as with single-copy DNA in a typical animal genome. In addition, filter transfer hybridization can be used to quantitate repetition frequency and sequence divergence and to distinguish patterns of repeated sequence organization.

Animals↗
PubMed1981

Smooth muscle relaxing drugs and guinea pig ileum.

The effects of various smooth muscle relaxing drugs on contractile responses to acetylcholine (ACh), Ba2+ and Ca2+, and on the tissue cyclic AMP levels were examined in the guinea pig ileum. Papaverine and theophylline caused a decrease both in the maximum height and the slope of dose-response curves induced by the three stimulants, and an increase in the cyclic AMP levels. Diltiazem and D-600 produced a decrease in the maximum and the slope of ACh and Ba2+ dose-response curves, shifted the Ca2+ dose-response curves to higher concentrations, in a parallel manner, but failed to change the cyclic AMP levels. Etomidoline and benactyzine shifted the curves for the three stimulants in parallel to the right, but at higher concentrations depressed the maximum of ACh and Ba2+ responses with a further parallel shift. These drugs exerted little influence on the basal level of tissue cyclic AMP, but etomidoline significantly depressed the Ba2+ -induced increase in cyclic AMP level. The smooth muscle relaxing drugs used could be classified in three types, thereby suggesting that there are at least three different mechanisms involved in smooth muscle relaxing action.

Acetylcholine↗
PubMed1981

Determination of the pleural edge by gamma-ray transmission computed tomography.

A technique is described for transaxial imaging of the thorax during pulmonary perfusion study. The contours of the air-containing lungs were obtained by gamma-ray transmission data from a Tc-99m plane flood source. These images were overlaid on the emission tomogram of the pulmonary blood flow obtained with Tc-99m MAA. It permits reliable detection of peripheral perfusion defects. Use of the results from these measurements can be applied to evaluate marginal hypoperfusions of the lungs.

Adult↗
PubMed1981

Clinical evaluation of thallium-201 emission myocardial tomography using a rotating gamma camera: comparison with seven-pinhole tomography.

Single-photon emission computed tomography (SPECT) for thallium-201 myocardial imaging with a rotating gamma camera was evaluated in comparison with planar imaging and seven-pinhole tomography (7P). Cardiac phantom studies indicated that defects 2 cm in diameter can be visualized by both tomographic methods, but the 7P method showed propagation of the image into nearby planes, with lower image contrast. In a clinical study of 47 patients with myocardial infarction, both sensitivity and specificity for the SPECT system were high (96 and 89%, respectively); the 7P system, on the other hand, showed good sensitivity (93%) but poor specificity (68%), while planar imaging performed conversely (75 against 89%). The overall accuracy was not significantly improved in the 7P method (planar: 81%, 7P: 83%, and SPECT: 94%). Our study indicates that SPECT, which can reconstruct reliable tomographic sections in either the transaxial, frontal, or sagittal planes, will result in a remarkable improvement in the clinical evaluation of ischemic heart disease.

Adolescent↗