[Hypolipodemic action of zhikeqing]

Zhikeqing is a compound prescription of Chinese herbs. It has been proved shown to possess an obvious effect on lipid and lipoprotein cholesterol contents in the serum of hyperlipidemic mice or rats.

Concentration and detection of hepatitis A virus and rotavirus from shellfish by hybridization tests

A modified polyethylene glycol precipitation method for concentration of virus followed by a new method to recover nucleic acid was used to detect hepatitis A virus (HAV) and rotavirus (SA11) in shellfish (oysters and hard-shell clams) by hybridization tests. Infectious virus, seeded into relatively large quantities of shellfish, was recovered consistently, with greater than 90% efficiency as measured by either in situ hybridization (HAV) or plaque assay (rotavirus SA11). Viral nucleic acid for dot blot hybridization assays was extracted and purified from virus-containing polyethylene glycol concentrates. Separation of shellfish polysaccharides from nucleic acid was necessary before viral RNA could be detected by dot blot hybridization. Removal of shellfish polysaccharides was accomplished by using the cationic detergent cetyltrimethylammonium bromide (CTAB). Use of CTAB reduced background interference with hybridization signals, which resulted in increased hybridization test sensitivity. After polysaccharide removal, dot blot hybridization assays could detect approximately 10(6) physical particles (corresponding to approximately 10(3) infectious particles) of HAV and 10(4) PFU of SA11 rotavirus present in 20-g samples of oyster and clam meats. These studies show continuing promise for the development of uniform methods to directly detect human viral pathogens in different types of shellfish. However, practical applications of such methods to detect noncultivatable human viral pathogens of public health interest will require additional improvements in test sensitivity.

The economic law of population distribution and migration

"The economic law of population distribution and migration has been studied chiefly based on the Chinese situation. The distribution and development of productive forces decide the distribution and migration of population, and in turn, the latter influences the former. The population distributions in three different stages of social development, namely agricultural, industrial and information society, are described. A new concept in population economics is introduced, i.e. population economic density, which is different from the concept of population density. The formula of population economic density is P(population)/R(resources). Many kinds of migration are analysed, and it is believed that the main efficient cause of migration is economy."

The transformation of the agricultural population and the urbanisation process in China

"Nine causes for the occurrence of surplus agricultural labour with the modernisation of agriculture have been identified. Several solutions to this problem are presented. Urbanisation of the agricultural population in a way suited to China's characteristics is necessary, important and possible." An example of labor saving through mechanization in Heilongjiang province is presented.

Detection of hepatitis A virus in estuarine samples by gene probe assay

The development and use of gene probe assays for rapid, sensitive and specific detection of hepatitis A virus in natural estuarine settings are described. Potentially health hazardous water-borne dissemination of hepatitis A virus was detected by dot hybridization in sewage-polluted estuarine, bayou and lake waters of coastal Texas.

Detection of hepatitis A virus by hybridization with single-stranded RNA probes

An improved method of dot-blot hybridization to detect hepatitis A virus (HAV) was developed with single-stranded RNA (ssRNA) probes. Radioactive and nonradioactive ssRNA probes were generated by in vitro transcription of HAV templates inserted into the plasmid pGEM-1. 32P-labeled ssRNA probes were at least eightfold more sensitive than the 32P-labeled double-stranded cDNA counterparts, whereas biotin-labeled ssRNA probes showed a sensitivity comparable with that of the 32P-labeled double-stranded cDNA counterparts. Hybridization of HAV with the ssRNA probes at high stringency revealed specific reactions with a high signal-to-noise ratio. The differential hybridization reactions seen with probes of positive and negative sense (compared with HAV genomic RNA) were used to detect HAV in clinical and field samples. A positive/negative ratio was introduced as an indicator that permitted a semiquantitative expression of a positive HAV reaction. Good agreement of this indicator was observed with normal stool samples and with HAV-seeded samples. By using this system, HAV was detected in estuarine and freshwater samples collected from a sewage-polluted bayou in Houston and a saltwater tributary of Galveston Bay.

Detection of hepatitis A virus in seeded estuarine samples by hybridization with cDNA probes

The development and trials of a nucleic acid hybridization test for the detection of hepatitis A virus (HAV) in estuarine samples within 48 h are described. Approximately 10(4) physical particles of HAV per dot could be detected. Test sensitivity was optimized by the consideration of hybridization stringency, 32P energy level, probe concentration, and nucleic acid binding to filters. Test specificity was shown by a lack of cross-hybridization with other enteroviruses and unrelated nucleic acids. Potential false-positive reactions between bacterial DNA in samples and residual vector DNA contamination of purified nucleotide sequences in probes were eliminated by DNase treatment of samples. Humic acid at concentrations of up to 100 mg/liter caused only insignificant decreases in test sensitivity. Interference with hybridization by organic components of virus-containing eluates was removed by proteinase K digestion followed by phenol extraction and ethanol precipitation. The test is suitable for detecting naturally occurring HAV in samples from polluted estuarine environments.