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Biomedical subjects

T Nishisaka

Publications and source records attributed to T Nishisaka.

28 records · Page 2Linked to original sources
PubMed1985

Myenteric enkephalin neurons around the laser-photocoagulation necrosis: an immunocytochemical investigation in the guinea pig jejunum and proximal colon.

Laser irradiation-caused features of neuronal regrowth containing enkephalin-like immunoreactivity in the myenteric plexus around the necrosis were investigated in the guinea pig jejunum and proximal colon using an antiserum to methionine-enkephalin-Arg6-Gly7-Leu8. The power level and irradiation time of the argon laser beam were adjusted to make a coagulation spot of about 0.5 mm in diameter. A distinct accumulation of the immunoreactivity occurred in the laser photocoagulated ends of the enkephalin neuron processes. Regeneration of the severed axon-like process took place in the following order: swelling and budding at the severed proximal end; elongation and branching of newly-formed nerve fibers; and formation of a tangled overgrowth. Approximately 43-90 hrs after the laser microsurgery, immunoreaction of the enkephalin neuron perikarya was stronger in the first several rows of ganglia, on both the oral and anal sides of the laser necrosis. In the jejunum, an increase in the intensity of the immunoreaction was more prominent on the oral side than on the anal side, whereas the proximal colon displayed an opposite state. In the jejunum, the anally-directed axon-like process of the enkephalin neurons transported a larger amount of the immunoreactivity as compared with the orally-directed wing-ramuli. This paper seeks to prove that the laser irradiation combined with immunocytochemistry may provide a simple and reliable methodology for the study of the projections of enteric neurons.

Animals↗
PubMed1976

Pathological studies of the animals replaced totally with the artificial heart. Part I. Concerning lungs, natural heart, and brain.

Pathological studies using routine pathological technics, microangiography and electron microscopy were performed on the 28 goats with an artificial heart (including 2 goats which survived for 30 and 37 days). In this paper, the brain, natural heart, and lungs of the goats were discussed. No special findings were seen in the brain except for rare infarcted areas. The natural heart almost always showed infarction-like lesions in the sub-endocardium and myocardium at the cut surface. The longer the animal survive, these findings became the more serious. The light microscopic findings on the lungs were classified into 6 groups. The most important findings of them are massive, diffuse exsudation with hemorrhage and its changes to chronic status. The main pathophysiological status, causing the pulmonary lesions, seemed to be peripheral circulatory insufficiency with increased permeability of peripheral vessels, especially of venulae. Thrombi were detected more frequently in the kidneys and lungs than in any other organs. The vascular walls where the thrombi were attached to, where often seen to be damaged, so that almost all thrombi were thought to be formed in the local vessels in situ, but not in the artificial heart. The main clinical causes to the pulmonary insufficiency were thought to be surgical operation including anesthesia, functional incompleteness of the artificial heart, etc.

Angiography↗
PubMed1976

Pathological studies of the animals replaced totally with the artificial heart. Part II Concerning liver, gastrointestinal tract, kidney, and general discussion.

Twenty-eight goats with an artificial heart (AH) were studied pathologically. Being continued from the previous report, the liver, gastrointestinal tract, and kidneys were taken up in this paper and finally, general discussion was done to get our ideas in shape concerning the pathophysiological status of the goat. Central necrosis of the liver was always observed in the goats which survived for over 140 hours. This finding seemed to be caused mainly by circulatory insufficiency of the portal vein at the latter half of the survival time. Microscopic findings of degeneration, necrosis, and edema were commonly observed at the walls of gastrointestinal tracts, when goats showed poor apetite, mucous feces and constipation. But these problems have been improved by application of a new control method to regulate the output of AH system within a goat's physiological range since October 1974. The lesions seen in the kidneys are classified into 5 groups. The most important findings of them are lower nephron nephrosis and cortical necrosis, both of which indicate the occurrence of long standing vasoconstriction of proximal renal arteries. By means of microangiographic method and others, thrombi were detected frequently in the kidneys. The vascular walls, where thrombi were attached to, were often damaged. Therefore, these thrombi were thought to be formed in the local vessels in situ through renal circulatory insufficiency. The renal pathological lesions have been also improved and severe renal failure from which the previous goats could not escape, has been lessened since the application of a new AH control method. As a whole, the main pathophysiological status of the animals replaced by the AH are thought conclusively to be peripheral circulatory insufficiency. This would be caused by abnormal hemodynamics, so that, the essential clinical etiology is thought to be AH function itself.

Animals↗
PubMedDate not supplied

Comparison of phototoxicity mechanism between pulsed and continuous wave irradiation in photodynamic therapy.

A study has been conducted in which HeLa cells are incubated with hematoporphyrin derivative (HpD) for 1 h (1 microgram/ml of HpD in PBS) to compare the use of continuous wave (CW) and pulsed laser (10 Hz repetition rate and 7-9 ns pulse width) light for photodynamic therapy. Cytotoxic effects on the cells are evaluated by the 3-(4,5-dimethyl-2-thiazolyl)-2-5-diphenyl-2H-tetrazolium bromide (MTT) assay and the fluorescein diacetate (FDA)/propidium iodide (PI) stain method using a flow cytometer. The type of cell death is estimated by analysis of the DNA content and observation of the nuclear morphology. The cytotoxicity ratio of cells irradiated by pulsed laser light is estimated to be lower than that for CW laser light. The viability of cells that received pulsed laser light gradually decreases, whereas no significant changes are found in the cells irradiated with CW laser light with the elapse of post-irradiation time. The type of cell death differs between the pulsed and CW laser light irradiations. These findings suggest that the cytotoxic efficacy of the excitation light source is displayed by the difference in the type of cell death, namely apoptosis or necrosis.

Cell Survival↗