Hydrophilic interaction liquid chromatography (HILIC)—a powerful separation technique

Hydrophilic interaction liquid chromatography (HILIC) provides an alternative approach to effectively separate small polar compounds on polar stationary phases. The purpose of this work was to review the options for the characterization of HILIC stationary phases and their applications for separations of polar compounds in complex matrices. The characteristics of the hydrophilic stationary phase may affect and in some cases limit the choices of mobile phase composition, ion strength or buffer pH value available, since mechanisms other than hydrophilic partitioning could potentially occur. Enhancing our understanding of retention behavior in HILIC increases the scope of possible applications of liquid chromatography. One interesting option may also be to use HILIC in orthogonal and/or two-dimensional separations. Bioapplications of HILIC systems are also presented

Outcomes for Resident-Identified High-Risk Patients and Resident Perspectives of Year-End Continuity Clinic Handoffs

BACKGROUND: Many patients nationwide change their primary care physician (PCP) when internal medicine (IM) residents graduate. Few studies have examined this handoff. OBJECTIVE: To assess patient outcomes and resident perspectives after the year-end continuity clinic handoff DESIGN: Retrospective cohort PARTICIPANTS: Patients who underwent a year-end clinic handoff in July 2010 and a comparison group of all other resident clinic patients from 2009–2011. PGY2 IM residents surveyed from 2010–2011. MEASUREMENTS: Percent of high-risk patients after the clinic handoff scheduled for an appointment, who saw their assigned PCP, lost to follow-up, or had an acute visit (ED or hospitalization). Perceptions of PGY2 IM residents surveyed after receiving a clinic handoff. RESULTS: Thirty graduating residents identified 258 high-risk patients. While nearly all patients (97 %) were scheduled, 29 % missed or cancelled their first new PCP visit. Only 44 % of patients saw the correct PCP and six months later, one-fifth were lost to follow-up. Patients not seen by a new PCP after the handoff were less likely to have appropriate follow-up for pending tests (0 % vs. 63 %, P < 0.001). A higher mean no show rate (NSR) was observed among patients who missed their first new PCP visit (22 % vs. 16 % NSR, p < 0.001) and those lost to follow-up (21 % vs. 17 % NSR, p = 0.019). While 47 % of residents worried about missing important data during the handoff, 47 % reported that they do not perceive patients as “theirs” until they are seen by them in clinic. CONCLUSIONS: While most patients were scheduled for appointments after a clinic handoff, many did not see the correct resident and one-fifth were lost to follow-up. Patients who miss appointments are especially at risk of poor clinic handoff outcomes. Future efforts should improve patient attendance to their first new PCP visit and increase PCP ownership. ELECTRONIC SUPPLEMENTARY MATERIAL: The online version of this article (doi:10.1007/s11606-012-2100-y) contains supplementary material, which is available to authorized users

Molecular evidence for a recent founder event in the UK populations of the Adonis blue butterfly (Polyommatus bellargus)

Contrary to accepted theories of post-glacial colonisation of the UK approximately 10,000 year BP (yBP), historical population data for Polyommatus bellargus suggests the butterfly was either extremely rare or not present before 1775. We examined the phylogeography of the species by sequencing the "hypervariable" mitochondrial control region of UK and French butterflies. Overall, 22 polymorphic nucleotide sites were identified within the control region. French specimens were highly variable, with 17 polymorphic sites, whereas most UK specimens were monomorphic. Average nucleotide diversity was 0.026 (SD 0.016, n = 8) in France, whilst the UK values ranged from 0.00 (n = 6) (for every UK population outside Dorset, n = 43) to 0.01 (SD 0.008, n = 7) (Dorset). The mean number of pairwise differences among the French samples was 7.42, whilst the UK values ranged from 0.00 (all populations except Dorset) to 0.295 (Dorset). One French haplotype differed from the predominant UK version by just a single nucleotide substitution. It seems implausible that the species can have been resident in the UK for 10,000 years without accumulating variation at this mitochondrial region. Thus, the results suggest that either a severe genetic bottleneck or founder event has occurred recently in the UK. © Springer Science+Business Media B.V. 2007

Analysis of endogenous D-amino acid-containing peptides in Metazoa

Peptides are chiral molecules with their structure determined by the composition and configuration of their amino acid building blocks. The naturally occurring amino acids, except glycine, possess two chiral forms. This allows the formation of multiple peptide diastereomers that have the same sequence. Although living organisms use L-amino acids to make proteins, a group of D-amino acid-containing peptides (DAACPs) has been discovered in animals that have at least one of their residues isomerized to the D-form via an enzyme-catalyzed process. In many cases, the biological functions of these peptides are enhanced due to this structural conversion. These DAACPs are different from those known to occur in bacterial cell wall and antibiotic peptides, the latter of which are synthesized in a ribosome-independent manner. DAACPs have now also been identified in a number of distinct groups throughout the Metazoa. Their serendipitous discovery has often resulted from discrepancies observed in bioassays or in chromatographic behavior between natural peptide fractions and peptides synthesized according to a presumed all-L sequence. Because this L-to-D post-translational modification is subtle and not detectable by most sequence determination approaches, it is reasonable to suspect that many studies have overlooked this change; accordingly, DAACPs may be more prevalent than currently thought. Although diastereomer separation techniques developed with synthetic peptides in recent years have greatly aided in the discovery of natural DAACPs, there is a need for new, more robust methods for naturally complex samples. In this review, a brief history of DAACPs in animals is presented, followed by discussion of a variety of analytical methods that have been used for diastereomeric separation and detection of peptides