Search

The effects of zinc depletion and repletion on spleen natural killer (NK) cell activity in aged mice were studied. Sixty 24-month-old male Balb/c mice were divided equally into three groups according to their weight: group I were fed the zinc-deficient diet (1.3 μg/g Zn). Group II were fed the zinc-supplemented diet (58 μg/g Zn), but their intake was restricted to the average daily amount consumed by the zinc-deficient group and group 111 were fed the zinc-supplemented diet (58 μg/g Zn) ad libitum. After 4 weeks, 10 mice were taken out from each group. The determinations of NK cell activity and plasma zinc level were performed in aged mice. Then, the other 10 mice in each group were all fed the zinc-supplemented diet. After another 4 weeks, they were also killed and used for the measurements of NK cell activity and plasma zinc level. The results showed that the level of plasma zinc and spleen NK cell activity were both significantly lower in zinc-deficient mice than in the restricted mice and in the ad libitum controls (P<0.05). There was no statistical difference in plasma zinc level and NK cell activity between the restricted mice and the ad libitum controls (P>0.05). Supplementation of zinc for 4 weeks enabled a satisfactory recovery of all the indices in the zinc-deficient mice. The data suggest that zinc deficiency significantly impairs the spleen NK cell activity in aged mice, which can be satisfactorily recovered by an adequate zinc supplementation.

Culture of human fetal cerebral neurons in serum-free medium was established. The enolase isoenzymes in the cultured neurons were fractionated by DEAE cellulose ion exchange chromatography. The total enolase activity was resolved into three peaks: Non-neuronal enolase (NNE or alpha alpha and alpha gamma) appeared in 10-day cultures, and the peak of neuron -specific enolase (NSE or gamma gamma) in the group added T3 appeared earlier (in 15-day cultures) than in the control group (20-day cultures). The percentage of gamma gamma enolase activity in the group added T3 was 2.55 times higher than that in the control group. In conclusion, the present study demonstrated that T3 in physiological concentration may promote the differentiation and maturation of neurons in cultures, verifying the expression of NSE and the switch-over of NNE (alpha alpha, alpha gamma) to NSE (gamma gamma).

Transformation and immortalization of human diploid fibroblasts by simian virus 40 (SV40) is at least a two-stage process, since transformants have a limited lifespan in culture. We have isolated immortalized derivatives (AR5 and HAL) from transformants generated with an origin-defective SV40 genome encoding a heat-labile large T protein (T antigen) and reported that both preimmortal and immortal transformants are continuously dependent on T antigen function for growth as determined by temperature shift experiments. In this study, we demonstrate complex formation between T antigen and the retinoblastoma susceptibility gene product (Rb) at 35 degrees C and observed a reduction in complexes under conditions of loss of T antigen function and growth inhibition at 39 degrees C. Viral oncogenes (polyomavirus large T protein and adenovirus E1A 12S protein) known to bind Rb were introduced into AR5 and HAL cells, both stably by gene transfer and transiently by virus vectors. Such double transformants are still unable to proliferate at 39 degrees C, although complex formation with the newly introduced oncogenes was demonstrated. We suggest that T antigen interacts with other cellular processes in addition to Rb to transform and immortalize human cells in culture. Our finding that p53-T antigen complexes are also temperature dependent in AR5 and HAL cells could provide such an additional mechanism.

Fluorescent determination of magnolol has been effected employing the sensitivity- and stability-enhancing action of the non-ionic surfaceactive emulsifier OP. As a result the accuracy of determination is raised by 2 orders of magnitude as compared to that of ultraviolet spectrophotometry.

This paper is based on the principle that the relative luminous strength of luminol-H2O2-Co2+ chemiluminescence quenching is extinguished by zinc. The contents of zinc in Flos Carthami, Radix Codonopsis Pilosulae, Radix Ginseng and Fructus Lycii were measured in optimol experimental conditions.