Failure to obtain positive MEM tests in either cell-mediated immune conditions in the guinea-pig or in human cancer.

The macrophage electrophoretic mobility test described by Caspary and Field (1971) and modified by Pritchard et al. (1973) was investigated in various models of cell-mediated immune conditions in the guinea-pig and in cancer in man. No positive results were obtained in 92 guinea-pig experiments. Only 17 of 154 experiments on 74 patients gave definite positives in experiments with human cancer and a few positive results were obtained with normal healthy subjects

Fusion of secretory vesicles isolated from rat liver

Secretory vesicles isolated from rat liver were found to fuse after exposure to Ca2+. Vescle fusion is characterized by the occurrence of twinned vesicles with a continuous cleavage plane between two vesicles in freeze-fracture electron microscopy. The number of fused vesicles increases with increasing Ca2+-concentrations and is half maximal around 10–6 m. Other divalent cations (Ba2+, Sr2+, and Mg2+) were ineffective. Mg2+ inhibits Ca2+-induced fusion. Therefore, the fusion of secretory vesiclesin vitro is Ca2+ specific and exhibits properties similar to the exocytotic process of various secretory cells. Various substances affecting secretionin vivo (microtubular inhibitors, local anethetics, ionophores) were tested for their effect on membrane fusion in our system. The fusion of isolated secretory vesicles from liver was found to differ from that of pure phospholipid membranes in its temperature dependence, in its much lower requirement for Ca2+, and in its Ca2+-specificity. Chemical and enzymatic modifications of the vesicle membrane indicate that glycoproteins may account for these differences