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Biomedical subjects

L W Chang

Publications and source records attributed to L W Chang.

At least 109 records · Page 6Linked to original sources
PubMed1978

Angiocardiographic differentiation of constrictive pericarditis and restrictive cardiomyopathy due to amyloidosis.

The cineangiocardiograms and coronary angiograms of two cases of amyloidosis of the heart were compared to six cases of constrictive pericarditis. Three angiographic differentiating points were seen: (1) right ventricular free wall motion showed diastolic restriction in both disorders, whereas the crista supraventricularis, which moved normally in constrictive pericarditis, demonstrated restriction in amyloidosis; (2) ventricles in cases of constrictive pericarditis showed subtle further expansion during atrial systole after initial rapid filling (atrial kick), while in both cases of amyloidosis there was no motion during atrial systole; (3) pericardial thickening in constrictive pericarditis was demonstrated by failure of the distal coronary arteries to reach the surface of the cardiac image. In amyloidosis, the distal coronary arteries normally reached the periphery of the image. All three signs may be useful in differentiation, but the first is the easiest to evaluate. The right anterior oblique or posteroanterior view is the recommended projection.

Amyloidosis↗
PubMed1978

The effects of Clostridium perfringens enterotoxin on rat and rabbit ileum: an electron microscopic study.

Intestinal epithelial damage caused by Clostridium perfringens enterotoxin in rats and rabbits was identified by light microscopy and compared at the surface (scanning electron microscopy), and the ultrastructural (transmission electron microscopy) levels. Under the light microscope damage to the epithelial layer of villus tips was clearly evident in cross-sections. Whole tissue viewed under the scanning electron microscope showed comparable tip localization of morpholigic damage in the form of collapsed tips and a dense covering of rounded blebs on the tips. Ulstructuctural observations included partial and sometimes complete disappearance of microvilli structures, budding of the terminal web region into the lumen, and even complete destruction of epithelial cells. These data suggest that C. perfringens enterotoxin attacks the epithelial cells with a preference for cells at the villus tips and causes damage at least in part by altering the cells' apical membranes. This then leads to cellular sloughing, death, and lysing.

Animals↗
PubMed1977

Electron microscopic observations of the mechanisms of terminal club formation in transected spinal cord axons.

Following transection of spinal cords, axoplasmic flow occurred in the axons both proximal and distal to the transection. In the proximal axonal stump, the direction of flow was proximo-distal whereas in the distal axonal stump the direction of flow was disto-proximal. Thus the flows in transected axons were all directed toward the point of transection. Electron microscopic observation of the spinal cord tissue bordering at the cut ends of spinal cord stumps showed various structural changes in the axons and myelin sheaths of the transected fibers near the cut ends which interfered with the axoplasmic flow leading to the formation of the terminal clubs. Five prototypes of changes in axons and myelin sheaths near the cut ends of fibers are described and the mechanism of terminal club formation is discussed. It seemed that the terminal clubs within the transected spinal cord stumps rere of the axoplasmic flow toward the cut ends of the fibers, and (2) interference by structural changes which developed within individual fibers consequent to spinal cord injury.

Animals↗
PubMed1977

Pathologic changes following chronic exposures to halothane: a review.

The toxic effects of halothane on the liver, kidney, and brain are reviewed. Increasing evidence has indicated that hepatic degeneration can be induced in several animal speices after exposure to halothane. Recent electron microscopic investigations have also revealed cytological degeneration of the liver cells after chronic exposure to subclinical levels of halothane. Degeneration of the kidney and the nervous system after halothane exposure have also been reported. The pathological effects of halothane on the neonatal (developing) liver, kidney, and brain are also demonstrated by electron microscopy. Although the full significance of these observations on experimental animals in relationship to human exposure is still not known, the indication of the toxic potential of halothane on the biological system is strong and deserves further investigation.

Animals↗
PubMed1977

The mechanism of spinal cord cavitation follwing spinal cord transection. Part 2. Electron microscopic observations.

The authors report their findings by electron microscopy after microsurgical subpial spinal cord transection in dogs. After cord transection, conspicuous myelin microcysts are formed in a background of otherwise intact cord tisue at a distance of 1 to 2 mm from the cut end of the cord, both proximal and distal to the transection, Seen through the electron microscope, the microcysts iss a myelin sac distended by fluid under pressure, containing a swollen axon filled with excessive axoplasmic organelles; that is, a terminal club. Later the microcysts and terminal clubs rupture. The large spaces within the microcysts are opened to heretofore small extracellular spaces and the spinal cord tissues are destroyed. Thus, microcysts are precursors of large cavitites seen at the ends of transcreted cord stumps. The formation of microcysts and their subsequent rupture, which leads to cord cavitation, is interpreted as an inherent response of cord tissue to injury, and the result of an abortive attempt at cord regeneration.

Animals↗
PubMed1977

The mechanism of spinal cord cavitation following spinal cord transection. Part 3: Delayed grafting with and without spinal cord retransection.

Cavitation adjacent to transection of spinal cords can be successfully eliminated by a second operation 1 week after the initial spinal cord transection. The second operation consists of removal of the necrotic spinal cord tissue, thus producing a gap. Segments of autogenous sciatic nerve are inserted into the gap between the spinal cord stumps. If the spinal cord is injured by retransection at the second operation, cavitation again occurs in the spinal cord stumps resulting in separation of the nerve grafts from the spinal cord. The results of the present experiments support the concept that lysosomal spinal cord autotomy, which causes spinal cord cavitation, is a self-limiting process and that once the spinal cord has completed the autotomy, the process will not occur again unless the spinal cord is agiain traumatized.

Animals↗
PubMed1975

Efficacy of acupuncture on osteoarthritic pain. A controlled, double-blind study.

Forty patients, randomly assigned to an experimental and a control group, participated in a double-blind study to assess the effectiveness of acupuncture in reducing chronic pain associated with osteoarthritis. The experimental group received treatment at standard acupuncture points, and the control group at placebo points. Analysis before and after treatment showed a significant (P less than 0.05) improvement in tenderness and subjective report of pain in both groups as evaluated by two independent observers and in activity by one observer. Comparison of responses to treatment between the two groups showed no significant (P greater than 0.05) difference. Thus, both experimental and control groups showed a reduction in pain after the treatments. These results may reflect the natural course of illness, and various attitudinal and social factors.

Acupuncture Therapy↗
PubMed1975

Ultrastructural evidence of the hepatotoxic effect of halothane in rats following in-utero exposure.

Eight pregnant Sprague-Dawley rates were exposed to 10 ppm halothane 8 hours/day and 5 days/week throughout pregnancy. Liver samples were obtained from the pups for electron microscopy. Degenerative changes such as myelin-figure formation, focal-cytoplasmic degradation; fatty changes and cellular necrosis were observed. Leukocytic infiltration and phagocytosis of the cellular debris by Kupffer cells were also evident. The present investigation has demonstrated the hepatotoxic effects of halothane on the foetal liver. The role of halothane as an occupational hazard is considered.

Animals↗