Preparation and properties of cloning inhibitory factor. I. Inhibition of HeLa cell cloning by stimulated lymphocytes and their culture supernatants

Lymphocytes stimulated by either phytohemagglutinin or tuberculin inhibit the cloning of HeLa cells. Cell-free supernatants prepared from such cultures of activated lymphocytes produced similar inhibition, whereas supernatants from unstimulated lymphocytes did not. The cloning inhibitory factor (CIF) produced by activated lymphocytes was nondialyzable and inactivated at 56 °C for 30 minutes. CIF did not produce cytolysis of cloned HeLa cells; time-lapse cinematography instead disclosed an additional, normally timed mitosis. Subsequent divisions, however, were markedly delayed. CIF did not depend for its activity on depletion of an essential nutrient from the HeLa medium.     

Hypothalamic bile acid-TGR5 signaling protects from obesity

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Metallo-beta-lactamase: structure and mechanism.

This past year has produced determinations of X-ray crystal structures for three metallo-beta-lactamases and the elucidation of the catalytic mechanisms for a monozinc and a dizinc enzyme. These advances shed light on how such a diverse group of enzymes are evolving to inactivate so efficiently a broad spectrum of beta-lactam antibiotics.