Induction of vitellogenin in primary monolayer cultures of cockerel hepatocytes.

A primary monolayer culture system from cockerel hepatocytes was established. The cultures synthesize and secrete proteins that comigrate with authentic serum proteins on polyacrylamide gels and are found in the same relative abundance. Addition of estradiol increased the synthesis of apoprotein B, found in very low density lipoprotein, under all culture conditions. Vitellogenin synthesis could not be induced directly by estradiol. However, when serum was obtained from cockerels injected with estradiol 4 days before blood collection and included in the culture medium, the cultures secreted a protein identified immunologically as vitellogenin by affinity chromatography. Furthermore, addition of growth hormone or prolactin to cultured cockerel hepatocyte monolayers resulted in the synthesis and secretion of a polypeptide that comigrates with authentic vitellogenin on polyacrylamide gels.     

胶体硒免疫层析法检测抗-HIV(1+2)抗体的评价

目的 对检测抗-HIV抗体的胶体硒免疫层析法进行评价。方法 用胶体硒免疫层析试剂检测HIV国家参考品、已经确证的临床阴、阳性标本，评价此法的灵敏度、特异性。结果 快速胶体硒法试剂特异性较好，灵敏度尚可，可以满足快速筛查抗-HIV的要求。结论 此法可用于紧急情况下的抗-HIV的筛查，鉴于其灵敏度有待进一步提高，目前尚不能替代酶标法的检测。同时，该法不适用于献血者献血前的筛查。     

Segregation of presynaptic inputs on an identified target neuron in vitro: structural remodeling visualized over time.

Sensory cells of Aplysia form chemical synapses with the motor cell L7 in culture. Under certain conditions, sensory cells will also form electrical connections with each other. Sites of chemical synaptic interaction between the sensory cells and L7 are located at varicosities along sensory cell processes that overlie the main axons of L7, since these structures have been shown ultrastructurally to contain active zones. Previous studies have suggested that the distribution of sensory cell varicosities can be restricted to exclusive regions of the motor cell by the presence of other sensory cells. We wished to investigate (1) how this segregated pattern is generated over time and (2) whether electrical coupling between sensory cells has an effect on this segregated pattern. Using fluorescent dye injection and low-light video microscopy, we visualized the distribution of varicosities for each of two sensory cells growing on L7. In cases in which sensory cells are not electrically coupled, the varicosities from these two cells are spatially segregated on the target after 4 d in culture but not after 2 d in culture. Examination of the varicosity distribution of the same sensory cells on the second and third day of growth indicated both an increased rate in the elimination of varicosities from previously occupied areas and a restriction of varicosity formation in new areas of the target when a second sensory cell is present. For sensory cells that are electrically coupled, varicosities from these cells were not spatially segregated on the target even after 4 d in culture. These observations in vitro suggest that segregation of synaptic inputs by Aplysia sensory cells, which show little spontaneous activity of action potentials, can emerge over time via a process that includes both the elimination of existing sensory varicosities and the restriction of new varicosity formation. Our results also suggest that electrical connections between presynaptic cells can disrupt the segregation of their varicosities on a target, resulting in significant changes in the developing connectivity.     

Identification and characterization of linear B-cell epitopes of beta-globulin, a major allergen of sesame seeds

BACKGROUND: The increased consumption of foods containing sesame seeds is paralleled by an increase in reported sesame-induced allergic reactions. OBJECTIVE: This study aimed at identifying and characterizing the linear B-cell epitopes of the 14-kd beta-globulin, the major allergen of sesame seed. METHODS: A peptide containing 71 amino acids (peptide B) was previously identified by us as the IgE-binding region on beta-globulin. To determine the amino acid sequence of the IgE-binding sites on peptide B, we synthesized overlapping peptides 20 and 10 amino acid residues long that span the entire length of peptide B, which were offset from each other by 10 and 2 amino acid residues, respectively. Sera from 20 subjects given diagnoses of allergy to sesame beta-globulin served to identify the epitopes by using the dot-blot test. RESULTS: At least 9 different IgE-recognition sites were identified on peptide B. Three of them, numbers 2, 3, and 13 (corresponding to amino acids 46-55, 48-57, and 76-86, respectively, in the beta-globulin sequence), appeared to be immunodominant IgE-binding epitopes. Also, these peptides were best recognized in terms of intensity of response. There was no obvious sequence motif shared by the 9 different IgE-binding epitopes of beta-globulin. However, approximately 60% of the amino acids represented in the epitopes are hydrophobic residues. CONCLUSION: Identification of the IgE-binding epitopes might provide a better understanding of the functional role the allergens play in the disease and might have implications for immunodiagnosis and probably immunotherapy.