[Determination of tetramethylpyrazine in traditional Chinese medicines by high performance liquid chromatography]

This paper reports a method for determining tetramethyl pyrazine in pilules, injections and extracts of Ligusticum chuanxiong by high performance liquid chromatography. The results showed the recovery rate to be higher than 97% and the coefficient of variation (CV) to be 1.39% (with in day) and 1.51% (day to day). The lowest detection amount was 0.005 micrograms. The method was easy, fast and accurate.

Three-stage stochastic epidemic model: an application to AIDS

A three-stage stochastic epidemic model extending the so-called classical epidemic process to one that includes time-dependent transition probabilities is described, and a solution to the appropriate set of forward differential-difference equations is given. When an individual can move from being a susceptible to one infected with the HIV virus to one diagnosed as having AIDS, we can use this general model to describe an AIDS epidemic process. We obtain expressions for the mean and variance of the number of AIDS cases for some special cases. By comparing these with actual data, it is suggested that, for some categories of cases (in particular, children), this model might be a plausible model to describe the underlying mechanism of the AIDS epidemic.

Phosphorylase kinase: development of a continuous fluorometric assay for the determination of catalytic activity

The preferential binding of 1-anilinonaphthalene-8-sulfonate by rabbit muscle phosphorylase a is the basis of a continuous fluorometric assay for phosphorylase kinase. The maximum rate of change in fluorescence (d delta F/dt) is dependent on both the concentration of phosphorylase kinase and on conditions, such as pH and calcium ion concentration, which affect the enzyme. Parallel measurements of the increases in fluorescence and of 32P incorporation demonstrate the existence of a distinct intermediate in the conversion of phosphorylase b to a. We have used the assay to monitor the increase in calcium-independent activity which accompanies the limited chymotryptic digestion of phosphorylase kinase.

[On the skinning of radix Adenophorae]

Traditional experience calls for the skinning of Radix Adenophorae. Depending on the chemical compositions, this paper presents a comparative study on the skin, the radix with skin and the skinned radix. The experimental results show that the contents of beta-sitosterol, saponins, amino acids and trace elements are highest in the radix with skin, and that the radix with skin and the skinned radix are similar in the contents of polysaccharides.

[Classify species of Pseudomonas pseudomallei into serotypes]

Species of P. pseudomallei can be classified into two serotypes, serotype I and serotype II, based on whether or not it contains a thermolabile antigen beside a thermostable one. Under the condition of lack of typing serum, by means of serum absorption test, we recognized a strain which contains a major thermolabile antigen. The antigen was purified by Sephadex G-200, and it was used to inoculate rabbits. With the immunoserum at hand, we identified 68 of the domestic chinese strains and 6 of alien strains for serotyping by bi-directional agar diffusion test. The results showed that 68 strains were identified serotype I, 3 strains serotype II, and the remaining 3 comparable with those reported indicating that strains of serotype I were found mostly in Asia, and that the serotype are unrelated to their existing environments, nor that of animal bodies, but connected with their existence in geographic distribution.

Photoregulation of beta-Tubulin mRNA Abundance in Etiolated Oat and Barley Seedlings

The effect of light on the abundance of beta-tubulin mRNA was measured in etiolated Avena sativa L. and Hordeum vulgare L. seedlings. Slot blot analysis employing an oat beta-tubulin cDNA clone was used to measure beta-tubulin mRNA levels. White light induced a 45% decrease in oat beta-tubulin mRNA abundance by 2 hours after transfer. A saturating red light pulse induced 40 and 55% decreases in beta-tubulin mRNA levels in oats and barley, respectively. Recovery of beta-tubulin mRNA levels was observed after a red light pulse but not after transfer to continuous white light. The red light induced decrease in oat beta-tubulin mRNA abundance was not reversible by a subsequent far-red light treatment. The mesocotyl portion of etiolated oat seedlings exhibited a more dramatic decrease in beta-tubulin mRNA abundance in response to red light than did the coleoptile portion. The results indicate that the well-documented effects of red light on the growth of etiolated seedlings are accompanied by changes in the expression of the beta-tubulin genes.

[Effects of tetrandrine on platelet aggregation, platelet adhesion and coagulation]

We examined the effect of tetrandrine on platelet aggregation, platelet adhesion and coagulation in vitro. The results showed that tetrandrine markedly inhibited the platelet aggregation induced by ADP or collagen. Tetrandrine also markedly inhibited platelet adhesion and thrombosis, but didn't change thrombin coagulation time and plasma coagulation time obviously.

[Determination of calcium carbonate, trace elements and amino acids in Os Sepiae]

This paper reports the determination methods for calcium carbonate, trace elements and amino acids in the traditional Chinese medicine Os Sepiae. The data provide a reference for the quality control of the drug.

A novel technique to measure the group velocity of sound in dispersive media

A technique is proposed for measuring the group velocity of sound by a frequency-modulated (FM) continuous wave (CW) technique. Detailed calculations are presented, showing that V(g)=(deltaomega(m)/deltaphi)d , where V(g), deltaomega(m), deltaphi, and d are, respectively, the group velocity, change of modulation frequency, phase change of the received signal detected by a biphase lock-in amplifier, and the distance traveled by the sound. The approach has the advantage of high resolution compared to the conventional time-of-flight measurement technique.