Comparison of different separative techniques in the quantitative determination of active compound enclosed in liposomal systems

The suitability of three different separative techniques, dialysis, gel filtration and centrifugation, for determining the percentage of active compound included (PAI) in liposomal systems was assessed. Two model compounds, glucose and vitamin E acetate were encapsulated in dipalmitoylphosphatidylcholine (DPPC), soybean lecithin (SL) and hydrogenated soybean lecithin (HSL) multilamellar vesicles (MLV). Vitamin E acetate PAI values from DPPC MLV liposomes obtained by dialysis, gel filtration and centrifugation, were compared with those determined by differential scanning calorimetry. Glucose PAI values from DPPC MLV liposomes, obtained using the same separative techniques, were compared with that calculated by taking into account the glucose content of the liposome internal aqueous phase on the basis of liposome mean size determined by light scattering.
Vitamin E acetate and glucose PAI values from SL and HSL liposomes were compared with those obtained for DPPC liposomes. Dialysis proved suitable for PAI determination for both lipophilic and hydrophilic compounds, centrifugation was found to be suitable only for the determination of lipophilic compound PAI values while gel filtration using Sephadex G-25M proved inadequate for the determination of PAI values for both lipophilic and hydrophilic compounds in the experimental conditions used in this study.     

316L不锈钢中添加Al后的抗腐蚀性能

合金中添加Al可提高其抗腐蚀性能.在316L不锈钢中添加不同含量的Al,研究了合成的合金在5%H2SO4中的均匀腐蚀速率和在65%浓HNO3中的晶间腐蚀速率.结果表明:合金均匀腐蚀速率和晶间腐蚀速率均随着Al含量增加先减小后增大;添加2.00%,4.00%Al的合金的均匀腐蚀速率和晶间腐蚀速率较低;添加了Al的合金的晶间腐蚀速率低于未加Al的合金.     

Prevalence, distribution, and diversity of Listeria monocytogenes in retail environments, focusing on small establishments and establishments with a history of failed inspections

Despite growing concerns about cross-contamination of ready-to-eat foods with Listeria monocytogenes, our knowledge about the ecology and transmission of L. monocytogenes in retail establishments has remained limited. We conducted a cross-sectional study to characterize the prevalence, distribution, and subtype diversity of L. monocytogenes in 120 New York State retail deli establishments that were hypothesized to present an increased risk for environmental L. monocytogenes contamination (i.e., small establishments and establishments with a history of failed New York State Agriculture and Markets inspections). Analysis of these data along with previously reported data for 121 predominantly larger retail establishments in New York State identified establishment size, geographic location, and inspection history as significant predictors of L. monocytogenes presence and prevalence. The odds of an establishment being L. monocytogenes positive were approximately twice as high for large establishments, establishments located in New York City, or establishments with poor inspection history (as compared with establishments without these attributes), even though correlation between location and inspection history complicated interpretation of results. Within an establishment, L. monocytogenes was significantly more prevalent on nonfood contact surfaces than on food contact surfaces; prevalence was particularly high for floors and in floor drains, sinks, the dairy case, and milk crates. L. monocytogenes subtype diversity differed between sites, with lineage I isolates significantly associated with nonfood contact surfaces and lineage II isolates significantly associated with food contact surfaces. Isolates belonging to the same ribotype were often found dispersed across multiple sites within an operation.     

A MARANTHUS CRUENTUS LECTIN: PURIFICATION, STABILITY, AND SOME BIOCHEMICAL PROPERTIES

Amaranth lectin from Amaranthus cruentus seeds was isolated, purified and partially characterized. The purification method used was based on its ability to interact with fetuin. Effects of temperature, pH and buffers and concentration were determined by measurement of lectin hemagglutination activity. Amaranth lectin biological activity was best maintained at temperatures between 4 and 30°C and pH's above or below 5. It was possible to store amaranth lectin at 4°C in acetate buffers, pH 4.8, for prolonged periods and to concentrate it 10-fold by ultrafiltration with only 18% loss of activity. A subunit molecular weight of 32,500 daltons was determined by SDS-PAGE for amaranth lectin.     

Physico-chemical properties of a protein-inhibitor of serine proteinases from the potato]

Serine proteases inhibitor with pl-7.3, isolated from potatoe tubers by isoelectric focusing procedure as described previously (V.V. Mosolov et al., Bioorganic Chem., 1, 1449, 1975), was homogeneous under ultracentrifugation, having sedimentation coefficient S20,w 2.8S. Its molecular weight, investigated by sedimentation equilibrium and gel filtration through Sephadex G-100, was found to be 32500 and 31500 respectively. The Stokes radius R and frictional ratio f/fo were found to be 24 A and 1.14. The molecular weight of the inhibitor as determined by sodium dodecylsulfate polyacrylamide electrophoresis was twice as low as determined in ultracentrifuge and by gel filtration procedure. It is suggested that the inhibitor is dimer and consists of two protomers of equal molecular weight.     

Clinical experience with technetium-99m stannous polyphosphate for myocardial imaging

Myocardial imaging with technetium-99m stannous polyphosphate was performed on 46 patients. Eleven patients had no cardiac disease, 22 had acute myocardial infarction, and 13 had stable arteriosclerotic heart disease. Distinct patterns of myocardial activity were noted: (1) the patients with no obvious cardiac disease showed no cardiac activity; (2) stable arteriosclerotic heart disease showed faint, ill-defined cardiac activity, primarily in the anterior or inferior aspect of the left ventricle; (3) acute myocardial infarction showed intense, focal, well-defined activity, with a shape that characterized the location of the infarct.