Using medicolegal data to support safe medical care: A contributing factor coding framework.

OBJECTIVE: Traditional medicolegal data analysis focuses on physician care, without a full acknowledgment of the effects of team, organizational, and system factors. We developed a patient safety-informed contributing factor framework to strengthen the coding and analysis of medicolegal data. MATERIALS AND METHODS: We incorporated patient safety theory and human factors science into our medicolegal case coding practices to improve our understanding of the many factors that contribute to medicolegal events. RESULTS AND DISCUSSION: A new framework was developed that has at its core, patients and their experience, and looks beyond the provider factors that are often the focus of medicolegal analysis to give greater consideration to the influence of team, organizational, and system factors. We anticipate that this substantial shift will strengthen our knowledge translation efforts to help improve the safety of medical care. CONCLUSION: We believe that reframing medicolegal case coding systems to better identify the influence of team, organizational, and system factors will increase the utility of this analysis in patient safety research, and health care quality improvement.

Inhibition of HIV Fusion by Small Molecule Agonists through Efficacy-Engineering of CXCR4.

CXC chemokine receptor 4 (CXCR4) is involved in multiple physiological and pathological processes, notably as a coreceptor for human immunodeficiency virus (HIV) cell entry. Its broad expression pattern and vital biological importance make CXCR4 a troublesome drug target, as disruption of the interaction with its endogenous ligand, CXC chemokine ligand 12 (CXCL12), has severe consequences. In fact, only one CXCR4 drug, the bicyclam antagonist and HIV entry inhibitor AMD3100 (Plerixafor/Mozobil), has been approved for clinical use, however only for stem cell mobilization-a consequence of CXCR4 antagonism. Here, we report the engineering of an efficacy switch mutation in CXCR4-F292A7.43 in the middle of transmembrane helix 7-that converted the antagonists AMD3100 and AMD11070 into partial agonists. As agonists on F292A CXCR4, AMD3100 and AMD11070 were less disruptive to CXCR4 signaling while they remained efficient inhibitors of HIV fusion. This demonstrates that small molecule CXCR4 agonists can have a therapeutic potential as HIV entry inhibitors.

Differences in Ostomy Pouch Seal Leakage Occurrences Between North American and European Residents.

PURPOSE: The purpose of this study was to compare experiences and concerns about pouch seal leakage between persons with ostomies residing in North America (Canada and the United States) and Europe (United Kingdom, Netherlands, Sweden, Germany, Belgium, France, and Italy). Differences in reported pouch wear time and accessories used between the 2 groups were also examined. DESIGN: Secondary analysis of data from a cross-sectional study (Ostomy Life Study). SUBJECTS AND SETTINGS: Responses from persons residing in European countries (n = 1939) were compared with responses of 1387 individuals residing in North American countries. METHODS: Persons with an ostomy completed a questionnaire that focused on 4 topics related to the daily use of an ostomy pouching system (pouch seal leakage, ballooning, appearance of pouching system such as color and size of the pouch and whether it is discrete under clothing, and coupling failure of 2-piece pouching systems). Pouch seal leakage was defined as stomal effluent seeping between the skin and the wafer of the ostomy pouching system. Statistical analysis was performed using a proportional odds model including various variable effects. Special attention was given to frequency of pouch seal leakage occurrences. All tests were 2-sided; P values ≤.05 were deemed statistically significant. RESULTS: Participants living in the North American countries indicated they were more likely to experience leakage from the ostomy (odds ratio = 2.610, 95% CI 2.187-3.115; P < .0001). Findings also indicated they were more likely to worry about pouch seal leakage than those in the European countries' data set (odds ratio = 2.722, 95% CI 2.283-3.246; P < .0001). Participants residing in the North American countries had significantly longer wear times than those participants in the European countries (P < .0001, χ test). The use of accessories was associated with a longer pouching system wear time. CONCLUSION: Study results suggest that participants from the North American countries indicated significantly more experience with and worries about leakage and longer wear time than the participants from the European population. Additional research is needed to determine the reasons for these differences.

Corrigendum: Differential CCR7 Targeting in Dendritic Cells by Three Naturally Occurring CC-Chemokines.

[This corrects the article on p. 568 in vol. 7, PMID: 28018341.].

Differential CCR7 Targeting in Dendritic Cells by Three Naturally Occurring CC-Chemokines.

The CCR7 ligands CCL19 and CCL21 are increasingly recognized as functionally different (biased). Using mature human dendritic cells (DCs), we show that CCL19 is more potent than CCL21 in inducing 3D chemotaxis. Intriguingly, CCL21 induces prolonged and more efficient ERK1/2 activation compared with CCL19 and a C-terminal truncated (tailless) CCL21 in DCs. In contrast, tailless-CCL21 displays increased potency in DC chemotaxis compared with native CCL21. Using a CCL21-specific antibody, we show that CCL21, but not tailless-CCL21, accumulates at the cell surface. In addition, removal of sialic acid from the cell surface by neuraminidase treatment impairs ERK1/2 activation by CCL21, but not by CCL19 or tailless-CCL21. Using standard laboratory cell lines, we observe low potency of both CCL21 and tailless-CCL21 in G protein activation and ß-arrestin recruitment compared with CCL19, indicating that the tail itself does not improve receptor interaction. Chemokines interact with their receptors in a stepwise manner with ultimate docking of their N-terminus into the main binding pocket. Employing site-directed mutagenesis we identify residues in this pocket of selective CCL21 importance. We also identify a molecular switch in the top of TM7 important for keeping CCR7 in an inactive conformation (Tyr312), as introduction of the chemokine receptor-conserved Glu (or Ala) induces high constitutive activity. Summarized, we show that the interaction of the tail of CCL21 with polysialic acid is needed for strong ERK signaling, whereas it impairs CCL21-mediated chemotaxis and has no impact on receptor docking consistent with the current model of chemokine:receptor interaction. This indicates that future selective pharmacological targeting of CCL19 versus CCL21 should focus on a differential targeting of the main receptor pocket, while selective targeting of tailless-CCL21 versus CCL21 and CCL19 requires targeting of the glycosaminoglycan (GAG) interaction.

Molecular Mechanism of Action for Allosteric Modulators and Agonists in CC-chemokine Receptor 5 (CCR5).

The small molecule metal ion chelators bipyridine and terpyridine complexed with Zn2+ (ZnBip and ZnTerp) act as CCR5 agonists and strong positive allosteric modulators of CCL3 binding to CCR5, weak modulators of CCL4 binding, and competitors for CCL5 binding. Here we describe their binding site using computational modeling, binding, and functional studies on WT and mutated CCR5. The metal ion Zn2+ is anchored to the chemokine receptor-conserved Glu-283VII:06/7.39 Both chelators interact with aromatic residues in the transmembrane receptor domain. The additional pyridine ring of ZnTerp binds deeply in the major binding pocket and, in contrast to ZnBip, interacts directly with the Trp-248VI:13/6.48 microswitch, contributing to its 8-fold higher potency. The impact of Trp-248 was further confirmed by ZnClTerp, a chloro-substituted version of ZnTerp that showed no inherent agonism but maintained positive allosteric modulation of CCL3 binding. Despite a similar overall binding mode of all three metal ion chelator complexes, the pyridine ring of ZnClTerp blocks the conformational switch of Trp-248 required for receptor activation, thereby explaining its lack of activity. Importantly, ZnClTerp becomes agonist to the same extent as ZnTerp upon Ala mutation of Ile-116III:16/3.40, a residue that constrains the Trp-248 microswitch in its inactive conformation. Binding studies with 125I-CCL3 revealed an allosteric interface between the chemokine and the small molecule binding site, including residues Tyr-37I:07/1.39, Trp-86II:20/2.60, and Phe-109III:09/3.33 The small molecules and CCL3 approach this interface from opposite directions, with some residues being mutually exploited. This study provides new insight into the molecular mechanism of CCR5 activation and paves the way for future allosteric drugs for chemokine receptors.

Pesticide levels and environmental risk in aquatic environments in China--A review.

China is one of the largest producers and consumers of pesticides in the world today. Along with the widespread use of pesticides and industrialization, there is a growing concern for water quality. The present review aims to provide an overview of studies on pesticides in aquatic environments in China. The levels in the water, sediment and biota were scored according to a detailed environmental classification system based on ecotoxicological effect, which is therefore a useful tool for assessing the risk these compounds pose to the aquatic ecosystem. Our review reveals that the most studied areas in China are the most populated and the most developed economically and that the most frequently studied pesticides are DDT and HCH. We show maps of where studies have been conducted and show the ecotoxicological risk the pesticides pose in each of the matrices. Our review pinpoints the need for biota samples to assess the risk. A large fraction of the results from the studies are given an environmental classification of "very bad" based on levels in biota. In general, the risk is higher for DDT than HCH. A few food web studies have also been conducted, and we encourage further study of this important information from this region. The review reveals that many of the most important agricultural provinces (e.g., Henan, Hubei and Hunan) with the largest pesticide use have been the subject of few studies on the environmental levels of pesticides. We consider this to be a major knowledge gap for understanding the status of pesticide contamination and related risk in China. Furthermore, there is also a lack of studies in remote Chinese environments, which is also an important knowledge gap. The compounds analyzed and reported in the studies represent a serious bias because a great deal of attention is given to DDT and HCH, whereas the organophosphate insecticides dominating current use are less frequently investigated. For the future, we point to the need for an organized monitoring plan designed according to the knowledge gaps in terms of geographical distribution, compounds included, and risks.

Biased and g protein-independent signaling of chemokine receptors.

Biased signaling or functional selectivity occurs when a 7TM-receptor preferentially activates one of several available pathways. It can be divided into three distinct forms: ligand bias, receptor bias, and tissue or cell bias, where it is mediated by different ligands (on the same receptor), different receptors (with the same ligand), or different tissues or cells (for the same ligand-receptor pair). Most often biased signaling is differentiated into G protein-dependent and ß-arrestin-dependent signaling. Yet, it may also cover signaling differences within these groups. Moreover, it may not be absolute, i.e., full versus no activation. Here we discuss biased signaling in the chemokine system, including the structural basis for biased signaling in chemokine receptors, as well as in class A 7TM receptors in general. This includes overall helical movements and the contributions of micro-switches based on recently published 7TM crystals and molecular dynamics studies. All three forms of biased signaling are abundant in the chemokine system. This challenges our understanding of "classic" redundancy inevitably ascribed to this system, where multiple chemokines bind to the same receptor and where a single chemokine may bind to several receptors - in both cases with the same functional outcome. The ubiquitous biased signaling confers a hitherto unknown specificity to the chemokine system with a complex interaction pattern that is better described as promiscuous with context-defined roles and different functional outcomes in a ligand-, receptor-, or cell/tissue-defined manner. As the low number of successful drug development plans implies, there are great difficulties in targeting chemokine receptors; in particular with regard to receptor antagonists as anti-inflammatory drugs. Un-defined and putative non-selective targeting of the complete cellular signaling system could be the underlying cause of lack of success. Therefore, biased ligands could be the solution.

Biased and constitutive signaling in the CC-chemokine receptor CCR5 by manipulating the interface between transmembrane helices 6 and 7.

The equilibrium state of CCR5 is manipulated here toward either activation or inactivation by introduction of single amino acid substitutions in the transmembrane domains (TMs) 6 and 7. Insertion of a steric hindrance mutation in the center of TM7 (G286F in position VII:09/7.42) resulted in biased signaling. Thus, ß-arrestin recruitment was eliminated, whereas constitutive activity was observed in Gαi-mediated signaling. Furthermore, the CCR5 antagonist aplaviroc was converted to a full agonist (a so-called efficacy switch). Computational modeling revealed that the position of the 7TM receptor-conserved Trp in TM6 (Trp-248 in position VI:13/6.48, part of the CWXP motif) was influenced by the G286F mutation, causing Trp-248 to change orientation away from TM7. The essential role of Trp-248 in CCR5 activation was supported by complete inactivity of W248A-CCR5 despite maintaining chemokine binding. Furthermore, replacing Trp-248 with a smaller aromatic amino acid (Tyr/Phe) impaired the ß-arrestin recruitment, yet with maintained G protein activity (biased signaling); also, here aplaviroc switched to a full agonist. Thus, the altered positioning of Trp-248, induced by G286F, led to a constraint of G protein active, but ß-arrestin inactive and thus biased, CCR5 conformation. These results provide important information on the molecular interplay and impact of TM6 and TM7 for CCR5 activity, which may be extrapolated to other chemokine receptors and possibly to other 7TM receptors.

Modulation in selectivity and allosteric properties of small-molecule ligands for CC-chemokine receptors.

Among 18 human chemokine receptors, CCR1, CCR4, CCR5, and CCR8 were activated by metal ion Zn(II) or Cu(II) in complex with 2,2'-bipyridine or 1,10-phenanthroline with similar potencies (EC(50) from 3.9 to 172 µM). Besides being agonists, they acted as selective allosteric enhancers of CCL3. These actions were dependent on a conserved glutamic acid at TM-7 (VII:06/7.39). A screening of 20 chelator analogues in complex with Zn(II) identified compounds with increased potencies, with 7 reaching highest potency at CCR1 (EC(50) of 0.85 µM), 20 at CCR8 (0.39 µM), and 8 at CCR5 (1.0 µM). Altered selectivity for CCR1 and CCR8 over CCR5 (11, 12) and a receptor-dependent separation of allosteric from intrinsic properties were achieved (20). The pocket similarities of CCR1 and CCR8, contrary to CCR5 as proposed by the ligand screen, were elaborated by computational modeling. These studies facilitate exploration of chemokine receptors as possible targets for therapeutic intervention.

Allosteric and orthosteric sites in CC chemokine receptor (CCR5), a chimeric receptor approach.

Chemokine receptors play a major role in immune system regulation and have consequently been targets for drug development leading to the discovery of several small molecule antagonists. Given the large size and predominantly extracellular receptor interaction of endogenous chemokines, small molecules often act more deeply in an allosteric mode. However, opposed to the well described molecular interaction of allosteric modulators in class C 7-transmembrane helix (7TM) receptors, the interaction in class A, to which the chemokine receptors belong, is more sparsely described. Using the CCR5 chemokine receptor as a model system, we studied the molecular interaction and conformational interchange required for proper action of various orthosteric chemokines and allosteric small molecules, including the well known CCR5 antagonists TAK-779, SCH-C, and aplaviroc, and four novel CCR5 ago-allosteric molecules. A chimera was successfully constructed between CCR5 and the closely related CCR2 by transferring all extracellular regions of CCR2 to CCR5, i.e. a Trojan horse that resembles CCR2 extracellularly but signals through a CCR5 transmembrane unit. The chimera bound CCR2 (CCL2 and CCL7), but not CCR5 chemokines (CCL3 and CCL5), with CCR2-like high affinities and potencies throughout the CCR5 signaling unit. Concomitantly, high affinity binding of small molecule CCR5 agonists and antagonists was retained in the transmembrane region. Importantly, whereas the agonistic and antagonistic properties were preserved, the allosteric enhancement of chemokine binding was disrupted. In summary, the Trojan horse chimera revealed that orthosteric and allosteric sites could be structurally separated and still act together with transmission of agonism and antagonism across the different receptor units.

Survival and complications after insertion of self-expandable metal stents for malignant oesophageal stenosis.

OBJECTIVE: To report on survival and complications after insertion of self-expandable stents in patients with malignant oesophageal stenosis. MATERIAL AND METHODS: Data were gathered retrospectively from the medical records of 92 consecutive patients in the period 1994-2003. The study comprised 68 men and 24 women (median age 72 years, range 46-93 years) with stenosis from cancer of the oesophagus (n=61), the gastric cardia (n=26) and the lung (n=5), located mainly above (n=4) or below (n=62) the carina, or at the gastro-oesophageal junction (n=26). One uncovered stent and six different covered stents were used. RESULTS: Median and mean survival times after stenting (n=92) were 83 (range 4-1102) and 125 days, respectively. Thirty-day mortality was 19% (n=17), and 7% (n=6) survived more than one year. Survival was neither significantly influenced by division of the patients into diagnostic subgroups nor by comparison of the three most frequently used stents. One, two, three and four stents were received by 76, 11, 4 and 1 patient(s), respectively. There was no stent-related mortality, and complications were bleeding 1 (1%), stent migration 7 (8%), recurrent stenosis 8 (9%) from both tumour overgrowth (n=8) and tumour ingrowth (n=2) when using uncovered stents. Thirteen (14%) patients were re-stented because of recurrent stenosis (n=8) including fistula formation to the left main bronchus (n=2) and stent migration (n=5). CONCLUSIONS: Use of self-expandable stents in patients with inoperable malignant oesophageal stenosis carried few complications and resulted in relatively long survival in comparison with similar studies.

[Surgery and stenting for oesophageal cancer]. / Kirurgi og stenting for cancer oesophagi.

BACKGROUND: The purpose of this study was to evaluate the results of surgery and stenting for operable and inoperable oesophageal cancer. MATERIAL AND METHODS: Retrospective patient materials with resection (n = 65, 1983-2002) or stenting (n = 59, 1994-2003) for primary oesophageal cancer. RESULTS: Mortality after surgery was 11% and 15% of the patients were re-operated. 36 (55%) had complications such as respiratory failure (n = 33), anastomotic dehiscence/perforation (n = 4), chylothorax (n = 1), haemorrhage (n = 3), wound rupture (n = 1), septicaemia (n = 2), arrhythmia (n = 4) and wound infection (n = 5). Median survival after surgery was 11 months. Survival after three years was 17%, after five years 8%. The stent procedure was without mortality but haemorrhage (n = 1) and stent dislocation (n = 2) occurred. 8 patients (14%) were re-stented for tumour stenosis (n = 6), fistula (n = 2) and dislocation (n = 1). Median survival after stenting was 78 days. Survival after 30 days was 80%, after one year 7%. INTERPRETATION: Resectable oesophageal cancer should be operated in fit patients, as survival is improved and some patients can be cured. Stenting is the main option in inoperable patients.