Four monoclonal antibodies against the calcium ATPase in sarcoplasmic reticulum (SR) of rabbit fast-twitch skeletal muscle were characterized using SDS-PAGE, Western blots and immunofluorescence. The ultrastructural distribution of the antigens was determined using post-embedding immunolabeling. The antibodies recognized the calcium ATPase in the SR but not in transverse (T-) tubule or plasma membranes. The antibody, D12, had the same binding affinity for the calcium ATPase from fast-twitch (rabbit sternomastoid) and slow-twitch (rabbit soleus) fibers and the affinity fell by 30% after fixation for electron microscopy in both types of muscle fiber. Ultrastructural studies revealed that the density of D12 antibody binding to the terminal cisternae membrane of extensor digitorum longus (edl) and sternomastoid fibers was on average seven times greater than in the slow-twitch soleus and semimembranosus fibers. Since the affinity of the ATPase for the antibody was the same in SR from fast- and slow-twitch muscles, the concentration of calcium ATPase in the terminal cisternae membrane of fast-twitch fibers was seven times greater than in slow-twitch fibers. This conclusion was supported by the fact that the concentration of calcium ATPase in light SR membranes was six times greater in SR from fast-twitch fibers than in SR from slow-twitch fibers. The results provide strong evidence that the different calcium accumulation rates in mammalian fast- and slow-twitch muscles are due to different concentrations of calcium ATPase molecules in the SR membrane.

Summary The fluorescent indicator of Ca2 + concentration, quin-2, has been used to measure the concentration of free Ca2 + in the cytoplasm of tumorigenic and non-tumorigenic human somatic cell hybrids. The cell hybrids were derived from the fusion of a HeLa derivative (D98 AH2) and normal human fibroblasts. The calcium concentration of the tumorigenic cell lines was 180+7nM and the level in the nontumorigenic cells was 136+6nM. This difference was statistically highly significant (P<0.001). Control experiments are reported which show that the level of 3a2+ measured is not influenced by cell density or by the concentration of quin-2-tetra-(acetoxymethyl)ester used in these experiments. The possible implications of this elevated level of cytoplasmic calcium in tumorigenic cells are discussed.

A prospective study was undertaken to determine the prevalence of intercurrent disease in dogs and cats presented for vaccination in general practice. Fifty‐two percent of animals were found to suffer from intercurrent disease and 3% had severe debilitating disease. A thorough clinical examination conducted at the time of routine vaccination appears to be an important element in maintaining companion animal health and welfare.

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Gentle procedures are described for the fractionation of bovine tear fluid by a combination of centrifugation, salt precipitation, gel filtration and ion exchange chromatography. Fractions are examined by gel electrophoretic immunological methods. Reference patterns are compiled and compared with bovine milk and serum patterns. Properties of some of th components are determined. Lactoferrin is isolated in two separate, but closely related, fractions. An acidic protein with a molecular weight of 23 000 daltons, is also isolated. Distinct heterogeneity is observed between individual animals, suggestive of a genetic polymorphism. A method is presented for the determination of the antibacterial activity of tear fluid and its fractions.