The electrical potential across a fine pore membrane doped with trioleoyl glyceride (triolein) and separating aqueous solutions of 0.5M NaCl and 0.5M KCl, respectively, was studied. It was found that this system showed rhythmic and sustained oscillations of electrical potential between the two aqueous solutions. These oscillations were attributed to the change of permeability of Na+ and K+ ions across the membrane, which originated from the phase-transition of triolein molecules within the fine pores.

Mathematics↗

PubMed1984

[Experimental studies on active specific immunotherapy using the immune reaction of low-dose irradiated tumor tissues. Comparison of the effects of tumor cells and mononuclear cells].

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Animals↗

PubMed1984

Detection of heterozygotes for fructose 1,6-diphosphatase deficiency by measuring fructose 1,6-diphosphatase activity in their cultured peripheral lymphocytes.

The fructose 1,6-diphosphatase activities in peripheral lymphocytes from the parents of a patient with fructose 1,6-diphosphatase deficiency were lower than the mean value of normal controls, but the value of the mother overlapped lower values for normal controls. The fructose 1,6-diphosphatase activities in lymphocytes of normal adults and the parents increased progressively during in vitro culture, but no enzyme activity could be detected in the lymphocytes of the patient even after culture. None of the values for the parents overlapped those of normal controls on either day 5 or 10 of culture. Thus, it seems probable that heterozygotes for fructose 1,6-diphosphatase deficiency can be distinguished from normal individuals by measuring the fructose 1,6-diphosphatase activity in their cultured lymphocytes.

Adult↗

PubMed1984

Rat adrenocortical carcinoma 494 autophosphorylating protein kinase, autophosphorylating protein kinase 500. Purification, biochemical and immunological characterization, and substrate specificity.

A novel autophosphorylating protein kinase, autophosphorylating protein kinase 500, independent of cyclic AMP, cyclic GMP, calcium, and calmodulin was purified from rat adrenocortical carcinoma 494 by ammonium sulfate fractionation followed by the chromatographic steps of DEAE-cellulose, gel filtration, cyclic AMP-epoxy Sepharose, and phosphocellulose. Sometimes two additional chromatographic purification steps of chromatofocusing and gel filtration were necessary for complete purification. The enzyme was homogeneous as evidenced by one- and two-dimensional sodium dodecyl sulfate-polyacrylamide gel electrophoresis. Sucrose density sedimentation studies indicated that Mr of the enzyme was 490,000, while ultracentrifugal analysis demonstrated a value of 481,400 (+/-7%). The protein was composed of two identical subunits each with Mr = 250,000. The enzyme molecule was slightly asymmetric with frictional and sedimentation coefficients of 1.28 and 18.20, respectively, and a Stokes radius of 66 A. Isoelectric focusing electrophoresis revealed a single peak with pI 4.6, indicating acidity of the protein. The enzyme self phosphorylated one or more of its serine residues. The reaction utilized the terminal phosphate of ATP; GTP was inactive. Divalent cations (5 mM Mn2+ or 10 mM Mg2+) were essential for optimum activity. Autophosphorylating protein kinase 500 did not phosphorylate the commonly used exogenous substrates such as histones, casein, phosvitin, or protamine. Analysis of autophosphorylating protein kinase 500 with rabbit anti-autophosphorylating protein kinase 500 IgG by immunoelectrophoresis and crossed immune electrophoresis demonstrated single arcs of precipitation, confirming the biochemical demonstration of enzyme purification and homogeneity. Indirect immunofluorescence studies revealed an intracytoplasmic localization of the enzyme in cultured and freshly isolated adrenocortical carcinoma 494 cells. Both cell types revealed an intensity of perinuclear enzyme fluorescence, but an absence of the enzyme in the nuclei or nucleoli. The anti-autophosphorylating protein kinase 500 IgG blocked the self-catalyzed phosphorylation of autophosphorylating protein kinase 500, providing immunological support of the biochemical results that autophosphorylation is an intrinsic characteristic of the enzyme. When autophosphorylating protein kinase 500 was incubated with membrane-bound ribosomes, it phosphorylated a Mr = 31,000 protein. This phosphorylation was blocked by the anti-autophosphorylating protein kinase 500 IgG.(ABSTRACT TRUNCATED AT 400 WORDS)

Adrenal Cortex Neoplasms↗