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Biomedical subjects

Y Shimada

Publications and source records attributed to Y Shimada.

At least 811 records · Page 45Linked to original sources
PubMed1980

Modification of Rhizopus delemar lipase by its binding with phospholipids.

Rhizopus delemar (ATCC 34612) lipase was modified by phospholipid (PL)-treatment so as to enhance its activity on lipoprotein. In order to detect change in lipase conformation in the modified state, a preliminary experiment was performed to remove PL from the PL-treated lipase solution which included PL nonessential to enhancement of lipoprotein lipase (LPL) activity. It was found that treatment with a mixture of isopropyl ether: n-butanol (3 : 1) was suitable for this purpose because of the stability of the enzyme. Changes in isoelectric point and alpha-helical content of lipase caused by PL-treatment were studied by means of isoelectric focusing and circular dichroism spectrum. The isoelectric point of lipase was found to shift to the acidic side on its binding with phosphatidylcholine (PC) or cardiolipin (CL). The circular dichroism spectra of the original lipase and PL-treated lipases indicated that the alpha-helical content of lipase decreased on its binding with PL. In CL-bound lipase, which was more greatly enhanced as to LPL activity than was PC-bound lipase, alpha-helical content was decreased to a larger extent than that of PC-treated lipase.

Cardiolipins↗
PubMed1980

Comparison of several methods for the measurement of urinary hippuric acid as an index of toluene exposure.

The levels of hippuric acid in the urine of people exposed to toluene vapour were measured by paper chromatography, direct colorimetry, high performance liquid chromatography and gas chromatography. The control was a similar group not exposed to toluene vapour. The values were analyzed statistically, conversion equations calculated, and the propriety of these equation discussed. Since the three chromatographic methods gave similar values, the measurement of urinary hippuric acid by these methods can be used as an index of toluene exposure. The colorimetric method gave higher levels the chromatographic methods, especially for the urine of people not exposed to toluene. This may have been due to glycine conjugates (other than hippuric acid) developing a similar color, resulting in elevated values for hippuric acid. This colorimetric method should be used with caution for biological evaluation of workers with low toluene exposure.

Air Pollutants, Occupational↗
PubMed1980

Scanning electron microscopy of the rat bile canalicular-ductular junction.

Scanning electron microscopy revealed two types of bile canalicular-ductular junctions in rats. 1. Several bile canaliculi converged to enter the terminal bile ductule by direct continuity, forming an ampulla just before the junction. The ampulla was about 2.5x6 micrometers, whereas the canalicular diameter was about 1.5 micrometer just before the ampulla and the ductular diameter was 1.2--4.0 micrometers. The ampulla was mainly walled by several hepatocytes and partly by a few ductular cells. The hepatocytes abutted on the bile ductular cells. 2. Bile canaliculi connected directly to the bile ductule as a side branch without forming the ampullary dilation. In this case, a part of the bile ductular canal was formed by the hepatocytes at the junction of the bile canaliculus with the bile ductule. This study confirmed the light microscopy observation of Lettule and McIndoe.

Animals↗
PubMed1979

Isolation and culture of motoneurons from embryonic chicken spinal cords.

A method is described for isolating cholinergic alpha motoneurons from the spinal cord of chicken embryos at stage 17-18 (Hamburger and Hamilton numbering), at the time when it has been shown that motoneurons withdraw from the mitotic cycle but neurons of other types and glia are still mitotic. Fragments of the ventral half of the spinal cord are incubated for 24 hr in the presence of 10 microM 1-beta-D-arabinofuranosylcytosine in order to eliminate dividing cells and are subsequently dissociated into a suspension of single cells. The following evidence has been obtained and suggests that these cells are neuronal and appear to be alpha motoneurons: (i) they are resistant to the lethal effect of arabinofuranosylcytosine, and thus are postmitotic at stage 17-18; (ii) when grown in vitro, they exhibit morphological characteristics similar to those of ventral spinal neurons, which include the ability to be stained with silver, Nissl, methylene blue vital stain at pH 6.5-7.0, and choline acetyltransferase histochemistry; (iii) they have high choline acetyltransferase activity; (iv) they are capable of forming functional synapses with muscle.

Animals↗
PubMed1979

Troponin in embryonic chick skeletal muscle cells in vitro. An immunoelectron microscope study.

The fine structurel distribution of troponin on thin filaments in developing myofibrils was investigated by the use of immunoelectron microscopy. Embryonic chick skeletal muscle cells grown in vitro were treated with antibodies against each of the troponin components (troponin T, I, and C) from adult chicken muscles. Each antibody was distributed along the thin filaments with a period of 38 nm. It is concluded that these newly synthesized regulatory proteins are assembled at their characteristic position from the initial phases of myofibrillogenesis.

Animals↗
PubMed1979

Evaluation of a hot-wire respiratory flowmeter for clinical applicability.

A hot-wire flowmeter was evaluated for clinical applicability. 1) Calibration with a syringe could be done if emptying duration was 1-15 s. 2) Outputs linearly decreased with decreasing concentration of N2 in O2. Outputs with CO2 in O2 and N2O in O2 represented nonlinear convex relationships with varying concentrations of CO2 and N2O. Correction for each gas mixture to be measured is required. 3) Outputs linearly decreased with decreasing barometric pressure. 4) Stability assessed with a piston respirator was excellent (within +/- 2% of syringe volume) after 15 min warmup time. However, daily calibrations are recommended in clinical situations. 5) Nebulization, if not excessive, was acceptable if the expired gas was measured at the mouth. 6) Hot-wire burning, which occurred when it was partially in contact with materials whose specific heat differed with air, was successfully protected with a simple shutoff circuit. 7) The possibility of producing nitrogen oxides by the catalytic action of the platinum hot-wire was denied by colorimetric determination. Interchangeability and sterilizability of transducers and improved mechanical strength with platinum-rhodium alloy are also discussed.

Carbon Dioxide↗