Biomedical subjects
Publications and source records attributed to B R Unsworth.
The lysosomes of both Novikoff heptoma and liver from Novikoff heptoma-bearing rats were found to be relatively intact structurally, lower in acid phosphatase activity, greatly depleted in number but with nearly normal membrane integrity when compared with normal liver.
Ribosomes isolated from unfertilised eggs of the sea urchin, Strongylocentrotus purpuratus, have a higher protein: RNA ratio than ribosomes extracted from blastula stage ribosomes. Approximately 64 additional protein equivalents are found per ribosome. Most of the proteins are of high molecular weight and are tightly bound, being resistant to high-salt and EDTA treatment. The majority of the proteins appear to be basic in nature and remain associated with the 40S subunit on dissociation of the ribosomes. The possible physiological significance of the additional proteins is discussed in terms of the activation of protein synthesis following fertilisation. Sea urchin ribosomes, isolated from various stages of development, showed differential protein-labelling patterns. The high molecular-weight proteins had preferentially higher specific activities and one ribosomal protein was particularly highly labelled, reaching a maximum at the gastrula stage of development. The functional role of this highly labelled protein during development is discussed.
Explore the source record for details and available documents.
Changes in specific activity and total activity levels of rhodanese in mouse kidney and liver were studied during development of the embryo, neonate and adult. The enzyme profiles during embryonic development were different for kidney and liver. The kidney showed a lower but constant activity from day 11 to 15, then an increase to reach the fully differentiated level at birth. The liver specific activity increased linearly from day 11 to reach a maximum 1 day before birth. The level of rhodanese may be correlated with the onset of organogenesis. The kidney results are discussed in terms of a protodifferentiated level of activity followed by a biphasic increase in specific protein synthesis.
A murine mammary tumor was cultured in vitro for 14 days, either in direct combination with various embryonic murine inductive tissues or separated by a Millipore filter from these tissues. From 456 test cultures and 269 control cultures of tumor alone, morphologic, histochemical, and autoradiographic evidence for cytodifferentiation was obtained in the tumor after exposure to inductive tissues directly or through the filter. There appeared to be a gradient in potency of the inductive tissues; embryonic mammary mesenchyme was the most active of the tissues tested. Tumor growth was not different from that of controls, however, when the cultured, inductive tissue-exposed neoplasm was returned to the murine host.
Explore the source record for details and available documents.
Explore the source record for details and available documents.
A mouse mammary tumor, adenocarcinoma BW 10232, was maintained in vitro for 14 days, separated from embryonic mammary mesenchyme by a Millipore filter. Tubules developed in the tumor; deoxyibonucleic acid synthisis declined; and a presumptive acid mucopolysaccharide matrix, not evident in the controls, appeared.
Explore the source record for details and available documents.
Explore the source record for details and available documents.
Explore the source record for details and available documents.
Explore the source record for details and available documents.
Explore the source record for details and available documents.
The effects of thyrotoxicosis on the contractile properties and development of muscle fatigue in the slow soleus (SOL) and fast extensor digitorum longus (EDL) muscles were examined in rats given 3 mg of L-thyroxine and 1 mg of L-triiodothyronine per kilogram of diet for 6 weeks. The hormone treatment produced significant decreases in the contraction time, one-half relaxation time, and twitch tension in the SOL, while the peak rate of tension development (+ dP/dt) and decline (- dP/dt) in this muscle were elevated. Additionally, the force-frequency curve was shifted to the right and, thus, resembled the curve of a normal fast-twitch muscle. In contrast, the contractile properties of the fast EDL were relatively unaltered by the hormone administration. Thyrotoxicosis also changed the SOL response to contractile activity as twitch tension, + dP/dt, and - dP/dt remained high, and a faster decline in muscle glycogen and an increase in lactate occurred compared to control muscles. These results clearly demonstrate a preferential effect of thyroid hormone on slow compared to fast skeletal muscle.