Publications by authors named "Markovac J"

Initiatives designed to reduce the disease burden and improve the health of the US population that focus on increasing access to health care have been disappointing. Progress requires multifaceted change. We must first acknowledge that the healthcare system is focused on reversing or modifying disease, not enhancing health.

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Transforming growth factor beta (TGF-beta) is a regulatory peptide found in many normal and neoplastic tissues, including brain, with a diverse range of cellular effects. The transmembrane biochemical signals by which TGF-beta exerts these effects and the second messenger systems that may amplify them are unknown. We investigated the effects of TGF-beta upon membrane phosphoinositol metabolism and protein kinase C activity in cultured astrocytes.

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We investigated the effects of inorganic lead upon calcium-, phospholipid-dependent protein kinase (protein kinase C) in brain microvessels isolated from 6-day-old rat pups. We found that (a) in broken cell preparations, lead at micromolar concentrations activates this enzyme to an extent equivalent to that of micromolar calcium (10.3 +/- 1.

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Recent growth studies in children suggest that there is no threshold for adverse effects from the universal exposure to inorganic lead. The biochemical mechanisms mediating low-level toxicity are unclear, but in several biological systems, lead alters calcium-mediated cellular processes and may mimic calcium in binding to regulatory proteins. Here we present evidence that lead stimulates diacylglycerol-activated calcium and phospholipid-dependent protein kinase, protein kinase C, partially purified from rat brain.

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We investigated the activation of protein kinase C in microvessels isolated from rat brain. We found that unstimulated kinase activity in microvessels from immature animals is soluble while that from adults is particulate. The tumor promoter, phorbol 12-myristate 13-acetate, and the diacylglycerol analog, 1-oleoyl-2-acetyl-sn-glycerol, caused the redistribution of protein kinase C activity to the membrane fraction in microvessels from immature rats.

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The effects of the mouse major histocompatibility complex, H-2, on phospholipid methyltransferase I and II activities were investigated on hepatocyte membranes from inbred, congenic and recombinant strains. Each methyltransferase was assayed individually by measuring the incorporation of radiolabel from S-adenosyl-L-[methyl-3H]methionine into endogenous phospholipids. Our results indicate that H-2 exerted a significant effect on methyltransferase I but not on methyltransferase II activity.

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