No abstract

The effect of space flight and microgravity on the chemical senses is reviewed. Skylab-4 and Soyuz 30-31 studies revealed changes in taste thresholds while no effect was found in a Canadian investigation (41-G) and conflicting results were obtained on another Soyuz mission. Two simulated microgravity studies found no effect on taste or smell sensitivity; while 5 other studies found an effect. Microgravity induces physiological changes including an upward shift of body fluids toward the head, which may lead to an attenuation of the olfactory component in the flavor of foods. Chemosensory changes may also relate to space sickness, Shuttle atmosphere, stress, radiation, and psychological factors.

It has been observed that 60–70% of breast cancer patients have estrogen receptors (ER) and that nearly two‐thirds of such patients respond favorably to endocrine therapy. Cytosolic ER and progesterone receptors (PgR) have been evaluated in the current study, among 146 black women with breast cancer in order to determine whether the distribution of ER and PgR differs from the national norm. The results showed following trends that were similar to reports from other institutions: (1) postmenopausal patients and primary tumors showed higher ER positivity than premenopausal patients and metastatic sites, respectively; (2) a significant correlation between the ER positivity and tumor grade; and (3) a higher PgR positivity in ER‐positive patients than in ER‐negative patients. However, statistically significant differences were observed in three parameters when compared to reports from other institutions on white patients: (1) a low incidence of ER‐positive (46%) and high incidence of ER‐negative (42%) tumors; (2) a higher incidence of poorly differentiated (55.5%) and a lower incidence of well differentiated (5.5%) tumors; tumor grade was independent of age, menopausal status, histopathology and stage; and (3) a higher percentage of patients discovered at a more advanced stage of the disease. The clinical implications of these results in explaining the relatively poorer survival of black women with breast cancer compared to whites is discussed. Whether this high incidence of PD tumors and thus a high incidence of ER negativity is due to ethnic differences and/or environmental and other factors remains to be elucidated.

No abstract

No abstract

The process conditions for recombinant hepatitis B surface antigen (HBsAg) extraction from transgenic potato were examined. The effects of temperature, the reducing agent beta-mercaptoethanol (BME), and proteinase inhibitors on the level of antigenic activity of recovered HBsAg were determined. Sedimentation profiles were performed to characterize HBsAg assembly into virus-like particles. Increasing the temperature of the sample for about 1 min increased the measured HBsAg antigenic activity. The optimum temperature was around 50 degrees C. A 3-fold enhancement of the antigenic activity was obtained in extract from transgenic potato expressing HBsAg, when monoclonal antibodies were used to assay for HBsAg. When antigenic activity was determined by polyclonal antibodies, no enhancement in the antigenic activity was obtained. Temperature may affect the conformation of the a epitope to which the monoclonal antibodies bind or alter the fluidity of surface lipid regions. BME increased the antigenic activity of HBsAg up to 4-fold when monoclonal antibodies directed against the a determinant were used, but there was no increase with polyclonal antibodies. This observation suggests that BME affects the structure or presentation of the a epitope. In the presence of BME and leupeptin, a proteinase inhibitor, higher antigenic activity was obtained. Leupeptin might protect the antigen, which might become more susceptible to proteolytic degradation after reduction, as a result of stimulation of sulfhydryl proteases. Although both temperature and BME increased the antigenic activity of HBsAg individually, when combined their interaction was antagonistic, resulting in reduced antigenic activity. Different proteinase inhibitors, including leupeptin, aprotinin, E-64, pefabloc, and pepstatin, had no significant effect on HBsAg from potato extract in a 2 h period in the absence of BME. The sedimentation profile of potato-produced HBsAg was determined in 5-30% sucrose gradients. Yeast-derived recombinant HBsAg was used as a positive control. The HBsAg from transgenic potato showed sedimentation and density properties that are very similar to the yeast-produced antigen, indicating assembly into virus-like particles. BME treatment did not change the sedimentation profile.

A structured, mechanistic model has been built for the kinetics of yeast cell lysis by microbial cell lytic enzymes, based on an understanding of the two-layer yeast cell wall structure and the properties of yeast-lytic enzyme systems. The model predicts the release of protein, peptides and carbohydrates from four cell structures: the outer and inner wall layers, the cytosol and organelles or proteins present in particles; it also predicts organelle or particle lysis or solubilization and the breakdown of released proteins to peptides. Applications of the model to design and optimization of selective product release are discussed.

No abstract