Best Practice Updates for Surgical Care in Weight Loss Surgery

To update evidence‐based best practice guidelines for surgical care in weight loss surgery (WLS). Systematic search of English‐language literature on WLS in MEDLINE, EMBASE, and the Cochrane Library between April 2004 and May 2007. Use of key words to narrow the search for a selective review of abstracts, retrieval of full articles, and grading of evidence according to systems used in established evidence‐based models. Evidence‐based best practice recommendations from the most recent literature on surgical methods and technologies, risks and benefits, outcomes, and surgeon qualifications and credentialing. We identified >135 articles; the 65 most relevant were reviewed in detail. Regular updates of evidence‐based recommendations for best practices in WLS are required to address rapid changes in surgical techniques and patient demographics. Key factors in patient safety include surgical risk factors, type of procedure, surgeon training, and facility certification.     

Identification and structure-activity relationships of a new series of Melanocortin-4 receptor antagonists

The identification and optimization of a series of acylguanidine-based melanocortin-4 receptor antagonists is discussed.     

ATPase Subdomain IA Is a Mediator of Interdomain Allostery in Hsp70 Molecular Chaperones

The versatile functions of the heat shock protein 70 (Hsp70) family of molecular chaperones rely on allosteric interactions between their nucleotide-binding and substrate-binding domains, NBD and SBD. Understanding the mechanism of interdomain allostery is essential to rational design of Hsp70 modulators. Yet, despite significant progress in recent years, how the two Hsp70 domains regulate each other''s activity remains elusive. Covariance data from experiments and computations emerged in recent years as valuable sources of information towards gaining insights into the molecular events that mediate allostery. In the present study, conservation and covariance properties derived from both sequence and structural dynamics data are integrated with results from Perturbation Response Scanning and in vivo functional assays, so as to establish the dynamical basis of interdomain signal transduction in Hsp70s. Our study highlights the critical roles of SBD residues D481 and T417 in mediating the coupled motions of the two domains, as well as that of G506 in enabling the movements of the α-helical lid with respect to the β-sandwich. It also draws attention to the distinctive role of the NBD subdomains: Subdomain IA acts as a key mediator of signal transduction between the ATP- and substrate-binding sites, this function being achieved by a cascade of interactions predominantly involving conserved residues such as V139, D148, R167 and K155. Subdomain IIA, on the other hand, is distinguished by strong coevolutionary signals (with the SBD) exhibited by a series of residues (D211, E217, L219, T383) implicated in DnaJ recognition. The occurrence of coevolving residues at the DnaJ recognition region parallels the behavior recently observed at the nucleotide-exchange-factor recognition region of subdomain IIB. These findings suggest that Hsp70 tends to adapt to co-chaperone recognition and activity via coevolving residues, whereas interdomain allostery, critical to chaperoning, is robustly enabled by conserved interactions.     

Identification of a telomeric DNA sequence in Trypanosoma brucei

A simple repetitive DNA sequence in the nuclear genome of Trypanosoma brucei, consisting of tandem repeats of the hexanucleotide 5' CCCTAA 3', was identified as being telomeric by several criteria. This sequence was specifically labeled with T. brucei genomic DNA as the template for in vitro nick translation by DNA polymerase I, and was present in Bal 31 nuclease sensitive, genomic restriction fragments of the large sizes expected in this organism for at least some telomeric regions. The same repeated sequence was found in six other flagellates tested. A segment of DNA from T. brucei including this telomeric sequence was cloned in pBR322 and characterized. The cloned segment contained a sequence highly homologous to the 3' ends of several variant surface glycoprotein mRNAs, upstream of the tandemly repeated hexanucleotide sequence.     

Multiple mixed-type attractors in a competition model

We show that a discrete-time, two-species competition model with Ricker (exponential) nonlinearities can exhibit multiple mixed-type attractors. By this is meant dynamic scenarios in which there are simultaneously present both coexistence attractors (in which both species are present) and exclusion attractors (in which one species is absent). Recent studies have investigated the inclusion of life-cycle stages in competition models as a casual mechanism for the existence of these kinds of multiple attractors. In this paper we investigate the role of nonlinearities in competition models without life-cycle stages.     

Effects of acclimation and latitude on the activity thresholds of the aphid Myzus persicae in Europe

Activity thresholds were measured in nine anholocyclic clones of the peach‐potato aphid Myzus persicae collected along a latitudinal cline of its European distribution from Sweden to Spain. The effects of collection origin and intra‐ and intergenerational acclimation on these thresholds were investigated. Low‐temperature (10°C) acclimation for one generation depressed the movement threshold and chill coma temperatures, with the largest reduction in movement threshold recorded for clone UK 1 (8.8–2.5°C) and in chill coma for UK 2 (4.8–2.0°C). High‐temperature (25°C) acclimation for one generation increased the heat movement threshold and heat coma temperature with the largest increase in the movement threshold (40.1–41.1°C) and heat coma (41.4–42.3°C) recorded for clone Swed 1. There was no further intergenerational acclimation over three generations. High‐temperature activity thresholds were less plastic than low‐temperature thresholds, and, consequently, thermal activity ranges were expanded following low‐temperature acclimation. No constant affect of acclimation was observed on chill coma recovery, although clonal differences were observed with Swed 1 and 3 requiring some of the longest complete recovery times. There was no relationship between latitude and activity thresholds with the exception of heat coma data where Scandinavian clones Swed 2 and 3 consistently displayed some of the lowest heat coma temperatures (e.g. 41.3°C for both clones at 20°C) and Mediterranean clones Span 1, 2 and 3 displayed some of the highest (e.g. 42.1, 41.9 and 42.5°C, respectively, at 20°C). These data suggest that clonal mixing could occur over a large scale across Europe, limiting local adaptation to areas where conditions enable long‐term persistence of populations, e.g. adaptation to higher temperatures in the Mediterranean region. It is suggested that aphid thermal tolerance could be governed more by clonal type than the latitudinal origin.     

Global patterns of geographic range size in birds

Large-scale patterns of spatial variation in species geographic range size are central to many fundamental questions in macroecology and conservation biology. However, the global nature of these patterns has remained contentious, since previous studies have been geographically restricted and/or based on small taxonomic groups. Here, using a database on the breeding distributions of birds, we report the first (to our knowledge) global maps of variation in species range sizes for an entire taxonomic class. We show that range area does not follow a simple latitudinal pattern. Instead, the smallest range areas are attained on islands, in mountainous areas, and largely in the southern hemisphere. In contrast, bird species richness peaks around the equator, and towards higher latitudes. Despite these profoundly different latitudinal patterns, spatially explicit models reveal a weak tendency for areas with high species richness to house species with significantly smaller median range area. Taken together, these results show that for birds many spatial patterns in range size described in geographically restricted analyses do not reflect global rules. It remains to be discovered whether global patterns in geographic range size are best interpreted in terms of geographical variation in species assemblage packing, or in the rates of speciation, extinction, and dispersal that ultimately underlie biodiversity.