Biomedical subjects

E Guerrero

Publications and source records attributed to E Guerrero.

27 records · Page 2Linked to original sources

PubMed1990

Hepatitis B surface antigen. Role of lipids in maintaining the structural and antigenic properties of protein components.

Most of the lipid components of hepatitis B surface antigen (HBsAg) can be removed by treatment with the non-ionic non-denaturing detergent beta-D-octyl glucoside (OG) followed by centrifugation through caesium chloride linear density gradients (density 1.15-1.32 g/ml). The conformational changes induced by the elimination of lipids decreased the helical content of HBsAg proteins from 52 to 28% as indicated by c.d. techniques. Measurements of the extent of quenching of protein fluorescence by iodide showed that half of the tryptophan residues which are buried in the native structure of HBsAg particles are brought close to the surface of the molecule by such conformational changes. The antigenic activity, as measured by binding to polyclonal antibodies, was decreased upon removal of lipids. Moreover, the six different antigenic sites recognized by our panel of monoclonal antibodies decreased their capacity to bind to the corresponding antibody when lipids were removed. However, the extent of this decrease differed for the different antibodies. Thus the apparent dependence of antibody binding on the lipid content seemed to indicate a greater involvement of the lipid-protein interaction for some of the epitopes than for others.

Antibodies, Monoclonal↗

PubMed1990

Investigation of ovarian neoplasia of low malignant potential for human papillomavirus.

Recent in situ hybridization studies have suggested the presence of human papillomavirus type 6 (HPV-6) DNA in ovarian cancer cells. An association between HPV and ovarian neoplasia of low malignant potential (LMP) has not been previously identified. Paraffin-embedded tissue blocks from 24 patients with LMP ovarian tumors were screened for human papillomavirus DNA. The patients ranged in age from 18 to 73 years. Corresponding microscopic slides from each tissue block were reviewed to confirm the histopathologic diagnosis. For identification of HPV genome, deparaffinized sections were subjected to the polymerase chain reaction to achieve amplification of DNAs of HPV types 6, 11, 16, and 18. For each HPV type, a 120-base-pair region of the E6 gene was targeted for amplification. Human papillomaviral DNA was not detected in the tissue specimens subjected to polymerase chain reaction. These results suggest that HPV types 6, 11, 16, and 18 are not likely to play a role in LMP ovarian tumors. These results do not totally exclude possible contributions of other HPV types.

Adolescent↗

PubMed1990

The antigenic structure of HBsAg: study of the d/y subtype determinant by chemical modification and site directed mutagenesis.

Lysine residue 122 of the major protein of HBsAg/adw has been shown previously to be involved in the d subtype determinant. We demonstrate here that the corresponding residue of the HBsAg/ayw, arginine 122, does not play such a critical role the y site of this antigen subtype. Thus, conversion by site directed mutagenesis of arginine 122 to lysine 122 in HBsAg/ayw does not result in the loss of y activity nor gain of d activity. Moreover, chemical modification studies of both the adw and ayw antigens with the reagents o-methylisourea and cyclohexanedione, demonstrate that arginine 122 plays at most only a minor role in this subtype antigenic site.

Antibodies, Monoclonal↗

PubMed1986

Changes in the protein fractions of human milk during lactation.

The changes in the absolute and relative contents of alpha- and kappa-caseins, lactoferrin, alpha-lactalbumin, serum albumin and lysozyme in human milk have been studied through the period of lactation. Protein fractions of 209 samples were analyzed by a discontinuous polyacrylamide gel electrophoresis method. beta- and kappa-caseins decreased from colostrum to mature milk although their relative percentages remained constant. They accounted for 12-15 and 9-13% of the total protein in human milk, respectively. Lactoferrin decreased in absolute and relative amounts with advancing lactation. This protein represented 32-19% of the human milk proteins. alpha-Lactalbumin slightly decreased from colostrum to transitional milk but there was an increase in mature milk by 16-30 days. The percentages of this protein in colostrum and mature milk were approximately 23 and 30%, respectively. Serum albumin also decreased with advancing lactation, but the differences between transitional and mature milk were not statistically significant. Lysozyme increased from colostrum to mature milk both in relative and absolute amounts. Colostrum contained about 262 micrograms/ml, and mature milk 1,246 micrograms/ml, representing 1.5 and 12.1% of total milk proteins.

Animals↗

PubMed1983