Transcriptional activation function of hepatitis B virus Pre S1 protein in yeast.

OBJECTIVE: To explore the feasibility of cloning of the hepatocyte receptor interacting with the Pre S1 protein of HBV by two-hybrid system. METHODS: Yeast expression plasmids encoding fusion proteins of full length or portions of Pre S1 of HBV and DNA binding domain of yeast protein GAL4 were constructed and used to transform yeast reporter strain SFY526. Reporter gene product beta-galactosidase activity was assayed as a measure of transcriptional activation in yeast. Mammalian expression plasmid encoding fusion proteins of full length Pre S1 and DNA binding domain of GAL4 was constructed and used to cotransfect hepatoma cell line Huh-7 together with CAT reporter plasmid. Cell extracts were assayed for CAT activity by thin-layer chromatography. RESULTS: The fusion proteins of full length Pre S1 protein and GAL4 DNA binding domain presented transcriptional activation function in yeast. The transcription activating sequence was localized to the 21 to 47 amino acids of Pre S1 protein. Fusion proteins of full length Pre S1 and GAL4 DNA binding domain did not show transcriptional activation function in mammalian cells. CONCLUSIONS: The transcription activating sequence of HBV Pre S1 protein in yeast overlaps the hepatocyte receptor binding site. The transcriptional activation function of HBV Pre S1 protein in yeast may prevent researchers from using yeast two-hybrid system to clone HBV receptor interacting with Pre S1 protein. However, the Pre S1 protein does not show transcriptional activation function in mammalian cells. Mammalian two-hybrid system may be a practical method to clone the HBV hepatocyte receptor interacting with Pre S1 protein.

[The introduction of breastfeeding in children under age of three in the counties of western China in 2005].

OBJECTIVE: The study was to describe the breastfeeding status of children under the age of three in counties of western China and to provide evidence to the government for decision-making on intervention. METHODS: A cross-sectional study with probability-proportional-to-size (PPS) sampling method was used. The information on breastfeeding was obtained through memory of the mothers. Fourteen thousand and seventy-seven children were studied. Data on breastfed status in counties of western China was compared with those of the children from the survey of the counties of western China in 2001. RESULTS: The breastfeeding rate of children under 3 years old in western China was 96.5%. However, the overall breastfed rate of children under 6 months were only 33.4%, with rates of 11.4% and 22.0% on exclusively and predominantly breastfed groups respectively. Timely first-suckling rate was 43.5% with the continued breastfeeding rate (1 year) as 64.9%, but the continued breastfeeding rate (2 year) was only 9.7%. Reasons causing mothers to wean would include according to her own intention and to be able to attend the physical labor while exclusive breastfeeding under 6 months was for the growth and development of children, which might reduce the two-week prevalence of diarrhea. Major risks of exclusive breastfeeding of children under 6 months were seen as: level of education of the mothers, economic depression of the counties and mother's nationality (if as minority). CONCLUSION: Most of the children were ever or being breastfed at the time of interview with timely first-suckling took place earlier than in 2001. However continued breastfeeding did not last long. During these five years, the exclusive breastfeeding rate had been at low level, especially at the economic depression and the minority area.

[Assessment on nutritional status among children under 3 years using anthropometry in 40 counties of western China].

OBJECTIVE: To assess nutritional status among children younger than 3 years in 40 counties of western China, using anthropometry. METHODS: With cross-sectional study and random sampling, a survey with a sample size of 7252 was conducted in 40 counties of western China on children under 3 years old. Height and weight were measured and nutrition status was evaluated with WHO/NCHS reference using Z scores. RESULTS: SD of height for age (HA) and weight for age (WA) were 1.10 - 1.30 and 1.06 - 1.40, respectively and SD of WAZ for infants varied. The distribution of HA Z and WAZ shifted downward to 1 unit and 0.4 unit for distribution of weight for height (WHZ). The prevalence of stunting, underweight and wasting were 23.0%, 22.6% and 7.5% respectively. The prevalence rates were low among those yourger than 3 months. Stunting and underweight increased sharply after 6 months and reached 20% - 30%. Significant correlation was found between underweight and stunting or wasting with coefficients of 0.815 and 0.636, respectively. No correlation was found between stunting and wasting. CONCLUSION: The nutrition status adversely affected children as a whole but not only for individuals. There was a higher prevalence of malnutrition mainly on low height to children. Weight for age must be interpreted cautiously because of the inability of this indicator in distinguishing stunting and wasting just by itself. Assessment by anthropometry called for accurate information on age and measurement of height and weight.