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Biomedical subjects

L E Scheving

Publications and source records attributed to L E Scheving.

At least 109 records · Page 6Linked to original sources
PubMed1972

Circadian rhythm in uptake of tritiated thymidine by kidney, parotid, and duodenum of isoproterenol-treated mice.

The total uptake of [(3)H]thymidine by the mouse parotid gland, kidney, and duodenum exhibits a circadian rhythm. A single injection of isoproterenol changes the phasing and amplitude of these rhythms. Depending on the organ, there are certain points in the circadian time structure when isoproterenol stimulates or inhibits the uptake of thymidine; at other time points there is no difference between the responses to isoproterenol and to saline.

Animals↗
PubMed1971

Long-term organ culture of the salamander heart.

Beating salamander hearts were maintained in tissue culture for periods ranging from 1 to 6 months. After 1, 3, or 6 months of culture, six hearts, along with six control hearts, were fixed for electron microscopy. In control tissue, the sarcoplasmic reticulum usually demonstrated the normal pattern of paired, linearly arranged membranes, although in some cases, the reticulum showed a variation from these membranes to a series of small vesicles. There was no evidence of a T-system of tubules in any of the material examined. Desmosome-Z band complexes were observed in almost all sections of both control and experimental material. A possible role of these complexes in the excitation-contraction mechanism is discussed. In 3 month cultured material, alterations in normal myofibrillar pattern occurred. Small segments of myofibrils branched from one Z band to join the Z band of an adjacent myofibril, or appeared to be fraying out into the sarcoplasm. In 6 month cultured material, myofibrils were fragmented into short segments from which myofilaments frayed out into the sarcoplasm. This filamentous material may be remnants of myofilaments. Despite the morphological changes in myofibrils, the heart pulsation rate, established at the beginning, was maintained throughout the culture period. It is suggested that the alterations, observed in the experimental material, occurred in elements not essential for heart beat maintenance, or that these alterations have not yet progressed to a critical point of affecting the heart beat.

Animals↗