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Biomedical subjects

J Morgan

Publications and source records attributed to J Morgan.

At least 325 records · Page 18Linked to original sources
PubMed1975

Effect of pretreatment with prednisolone on enzyme efflux from isolated skeletal and heart muscle.

In a previous study, the efflux of creatine phosphokinase (CPK) and lactate dehydrogenase (LDH) which takes place from isolated mouse skeletal muscle was shown to be significantly reduced by pretreatment of the intact animal with diethylstilbestrol (DES). This compound is known to reduce the high serum enzymes present in patients with Duchenne's muscular dystrophy (DMD). Glucocorticoids also reduce the serum enzymes in DMD. The purpose of this study was to determine if pretreatment with the glucocorticoid, prednisolone, also lowered the efflux from isolated mouse skeletal and cardiac muscle. The results of these studies show that prednisolone pretreatment lowers the enzyme efflux from isolated skeletal muscle, but not from heart. There is an optimal dose which produces this reduction, which if exceeded, augments the efflux. Thus two agents are now known which lower the efflux of CPK and LDH from isolated skeletal muscle. These same two agents lower the high serum enzymes in DMD. This suggests, but does not prove, that the mechanism by which these agents lower the serum enzymes in DMD is by reducing enzyme efflux from skeletal muscle.

Animals↗
PubMed1975

Reduction of enzyme efflux from isolated skeletal muscle and heart by diethylstilbestrol.

It was previously shown that the efflux of creatine phosphokinase (CPK) and lactate dehydrogenase (LDH) from isolated mouse gastrocnemius was reduced 20% by a daily dose of 10 mug of diethylstilbestrol (DES) given for 14 or 21 days. The present study was designed to ascertain to what degree increasing doses of DES could suppress the CPK and LDH efflux from isolated skeletal muscle, and if DES affected heart in a similar manner. A total of 36 mice were injected with saline or 20, 100, 250 and 500 mug DES in saline daily for 14 days. The spontaneous efflux of CPK and LDH from the isolated gastrocnemius and heart was then compared in control and treated mice. The reduction in efflux was partially dose-dependent: increasing doses up to 100 mug DES per day, progressively reduced skeletal muscle efflux of CPK to 50% and LDH to 30%; higher doses had no additional effect. LDH efflux from heart was similarly reduced by DES, but over a narrower dosage range. This is the first agent shown to lower the spontaneous enzyme efflux from these two organs. These studies confirm that DES lowers the enzyme efflux from skeletal muscle; and though this effect is dose-related, the efflux could not be completely suppressed. The mechanism responsible for this reduction remains to be determined.

Animals↗
PubMed1973

Morphogenesis and ultrastructure of Geotrichum candidum septa.

The ultrastructure and mode of formation of septa of Geotrichum candidum were investigated by light and electron microscopy. The invaginations of the lateral membrane and wall appear to initiate at multiple points around the circumference of the cell; the immature septum subsequently assumes a cart-wheel shape, with branched spokes radiating from the center of the septum. Each face of the septum is covered with a membrane possessing hitherto undescribed structural differentiation; the membrane substructures are comprised of two central subunits encircled by 12 identical subunits. The diameter of the entire 12 plus 2 structure is 24 to 25 nm, and the diameter of each individual subunit is approximately 4 nm. The maturation of the septum appears to occur by further deposition of material along the branched skeletal regions. Numerous small openings (micropores), formed as a result of incomplete deposition, ultimately give rise to plasmodesmata. During arthrospore formation, the plasmodesmal canals and associated micropores are occluded by electron-dense materials, rendering each segment of the hyphae completely independent of the rest of the hyphae.

Cell Membrane↗