Aspects of the analytical ultracentrifuge determination of the molar mass distribution of polysaccharides

Molar mass or ‘molecular weight’ is one of the most fundamental parameters describing a macromolecule. Because of their polydisperse nature, polysaccharides are usually described by distributions of molar mass. SEC-MALS (size exclusion chromatography coupled to multi-angle light scattering) is often a convenient method of choice, but there are many instances where it is unsuitable. Modern AUC (analytical ultracentrifuge) methods provide a valuable alternative – now easier to use than before – and, after briefly reviewing some older procedures, we highlight two recently published and complementary methods, namely, the ‘Extended Fujita’ approach for the analysis of sedimentation velocity data and SEDFIT-MSTAR for the analysis of sedimentation equilibrium data. Nonideality needs to be considered and can be dealt with in a standard way. These methods can also indicate if associative phenomena are present, which can then be quantified using more complex AUC algorithms

Women veterans\u27 reproductive health preferences and experiences: a focus group analysis

OBJECTIVE: Although women veterans are seeking care at the Veterans Administration (VA) in record numbers, there is little information regarding women veterans\u27 experiences and preferences for reproductive health care services. We sought to characterize women veterans\u27 experiences with, and preferences for, reproductive health services in the VA. METHODS: We conducted five focus groups with a total of 25 participants using a semistructured interview guide to elicit women veterans\u27 experiences and preferences with reproductive health care. Women veterans\u27 utilizing VA health care at two VA facilities who responded to advertisements were selected on a first-come basis to participate in the study. We analyzed transcripts of these audio-recorded sessions using the constant comparative method of grounded theory. RESULTS: Five main themes emerged from the focus group discussions: 1) Women veterans prefer VA women\u27s clinics for comprehensive medical care; 2) Women veterans have had both positive and negative reproductive health experiences in the VA; 3) Women veterans experience knowledge gaps regarding VA coverage for reproductive health services; 4) Women veterans believe the VA should provide additional coverage for advanced infertility care and for newborns; and 5) Perceived gender discrimination shapes how women veterans view the VA. CONCLUSION: As the VA continues to tailor its services to women veterans, attention should be given to women\u27s reproductive health care needs. All rights reserved

Protein-like oligomerisation of carbohydrates

Sugar can, too: Many proteins form noncovalent and thermodynamically reversible oligomers, which can dictate a protein's functionality. For the first time, the presence of multiple oligomeric forms is shown in a whole class of polymeric carbohydrates, the 6-deoxy-6-aminocelluloses, using analytical ultracentrifugation as a probe

Carbohydrate Self-Association Protein-like Oligomerization of Carbohydrates

Many proteins form noncovalent and thermodynamically reversible oligomers, and the state of self-association can dictate a proteins functionality. DNA-binding proteins are very often dimeric, while other proteins exist as trimers (e.g. chloramphenicol transacetylase), tetramers (e.g. hemoglobin), or higher-order reversible association products (tubulin, viral coat proteins, sickle cell hemoglobin), with clear functional roles that have never been observed for carbohydrates. Although weak self-association in a polysaccharide has been shown, Water-soluble aminocelluloses were prepared by the reaction of tosyl cellulose with an excess of di-or trifunctional amines, namely with tris(2-aminoethyl)amine yielding 6-deoxy-6-(2-(bis(2-aminoethyl)aminoethylamino) (BAEA) cellulose (1-3), as depicted in To ascertain whether the higher-order species are different oligomers, a simple logarithmic relationship between sedimentation coefficient s and molecular weight M can be utilized, namely s % M b or, equivalently, s i /s 1 % (M i /M 1 ) b , where 1 denotes the monomer, i denotes the i th species, and b is a power-law coefficient that depends on the conformation (ca. 0.2 for rods, 0.5 for coils, and 0.7 for spheres). [4] Taking the first observable species in each case as the monomer, all five of the 6-deoxy-6-aminocelluloses follow the power-law relation with b % 0.7, a value consistent wit