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A rapid method to obtain large amount of VLDL and LDL by ultracentrifugation is described. The mixture of VLDL and LDL was isolated and concentrated from plasma by an ultracentrifugation at 265 000 g for 2 h. VLDL and LDL were separated and purified by a further ultracentrifugation at 265 000 g for 3 h. This method combines the advantages of both sequential flotation ultracentrifugation and density gradient ultracentrifugation. It can process a large volume of plasma in a short time. The purity of isolated VLDL and LDL was confirmed by the lipoprotein electrophoresis on agarose gel and PAGE and by the apolipoprotein electrophoresis on SDS-PAGE. This rapid economical method is of great value in practical application.

To improve the sensitivity of detecting biotin-labeled DNA Probes, a new fluorescent substrate of alkaline phosphatase, 4-methylum belliferylphosphate (4-mup) was studied instead of conventional BCIP-NBT. The result of dot-blot hybridization demonstrates that this new substrate can be used for the colorimetric detection of biotin-labeled probes after hybridization to immobilized nucleic acids. The sensitivity is about one order of magnitude higher than that of BCIP-NBT system, and the time required for color development is very short, only about five min. It is suggested that the Bio-SA-Bio-AP-4-MUP colorimetric detection system can be widely used in gene diagnosis.

In this experiment, we used morgrel dogs to study the effect of trauma on the neuro-endocrine and metabolic organs and the effects of hormones on metabolism by determining the levels of intracellular cAMP, cGMP and DNA. From the changes in intracellular nucleotides, we learned that many neuro-endocrine organs and the main metabolic organs are characteristic of predominance in alpha-adrenoreceptor after trauma, thereby leading to high blood sugar.

Macrophages were incubated with 125I-VLDL for 5 h in presence or absence of lipoprotein lipase (LPL) inhibitor, benzene boronic acid (BBA). Both the uptake and degradation of 125I-VLDL by macrophages were saturable, and the uptake and degradation curves were virtually identical. When macrophages were incubated with 125I-VLDL for 10 h in presence of BBA, the uptake and degradation of 125I-VLDL were still saturable. However, in absence of BBA, the uptake and degradation were no longer saturable. The results suggest that with macrophages incubated with VLDL for a shorter period, VLDL was taken up predominantly via receptor pathway, with a longer period of incubation, LPL played a striking role in uptake of VLDL.