Nucleic acid recognition by Toll-like receptors is coupled to stepwise processing by cathepsins and asparagine endopeptidase

TLR3, TLR7, and TLR9 are cleaved in the same step-wise manner in all immune cell types examined.

Toll-like receptor (TLR) 9 requires proteolytic processing in the endolysosome to initiate signaling in response to DNA. However, recent studies conflict as to which proteases are required for receptor cleavage. We show that TLR9 proteolysis is a multistep process. The first step removes the majority of the ectodomain and can be performed by asparagine endopeptidase (AEP) or cathepsin family members. This initial cleavage event is followed by a trimming event that is solely cathepsin mediated and required for optimal receptor signaling. This dual requirement for AEP and cathepsins is observed in all cell types that we have analyzed, including mouse macrophages and dendritic cells. In addition, we show that TLR7 and TLR3 are processed in an analogous manner. These results define the core proteolytic steps required for TLR9 function and suggest that receptor proteolysis may represent a general regulatory strategy for all TLRs involved in nucleic acid recognition.

Incidence and causes of colonoscopic perforations: a single-center case series

Perforations are known to occur after colonoscopy. In a consecutive study the localization of the perforation was determined, and the etiology of the perforation was classified as: therapeutic, barotraumatic or mechanical. A colonic perforation occurred in 26 of 19,135 patients (0.14%). In 13 cases (50.0%) the cause of perforation was mechanical, in nine (34.6%) the cause was a barotrauma (cecal blow-out), and in three cases (11.5%) it was due to a therapeutic procedure (coagulation or polypectomy). In one case (3.8%) data were not available. Cecal blow-out occurred significantly more often as a result of barotrauma, whereas perforation of the sigmoid occurred more often as a result of direct mechanical trauma. The risk of perforation after colonoscopy is rather low. Barotrauma due to insufflated air occurs more often than therapeutic perforation due to polypectomy or coagulation. Patients with a higher risk of perforation are those with diverticula in the sigmoid.

Differences in leisure activities between children with allergic rhinitis and healthy peers

OBJECTIVE

The symptoms of allergic rhinitis (AR) are frequently evoked when individuals with AR perform daily activities. Thus, AR may interfere the optimal participation in daily life, negatively impact the patient's productivity and quality of life (QOL). While most studies refer to adult with AR, this pilot study examined participation of children with AR as expressed in their daily activity preferences.

METHODS

Participants were 31 children with AR and 31 healthy children, aged 5-11 years. All children completed the Preference for Activities of Children (PAC).

RESULTS

Children with AR showed significantly lower preference to participate in skill-based, social and informal activities, as compared to their healthy peers (F(7,53)=2.61, p=0.02, ES-η(2)=0.27). Children with AR showed 5-20% lower preference to participate in activity than their typical peers.

CONCLUSIONS

AR may negatively impact children's preference to participate in daily activities. Treatment of children with AR should consider a multi-disciplinary intervention for encouraging their optimal development, improve their well-being and QOL.

Compartment-Specific Control of Signaling from a DNA-Sensing Immune Receptor

The endosomal compartment in which TLR9 is activated determines which cytokines are produced.

The effect of a Radiology Conference consultation on cancer patients management

BACKGROUND

The quantitative effect of consultation on cancer patient's management at a Radiology Conference was studied.

PATIENTS AND METHODS

This prospective study included consecutive patients presented at the Radiology Conference of the Division of Oncology. Following the case presentation and discussion, the patient's oncologist completed a questionnaire which asked whether the consultation at the conference added new information regarding the patient's disease status, whether it influenced patient management and, if so, to what extent.

RESULTS

Three hundred and eighty-three patients were included in the study. Significant new information was added for 189 (49%) patients and less consequential information was added for 134 (35%) patients. Major changes in management occurred in 143 (37%) patients after the Radiology Conference and minor changes were made in 56 (15%) patients. The influence of the cancer type on the rate of significant change in treatment and on the rate of major information addition was not statistically significant.

CONCLUSION

Consultation at a Radiological Conference in a tertiary center led to major changes in the management of 37% of the cancer patients presented and provided important information regarding the patient's disease in up to 50% of patients.

Thermodynamics of the Lévy spin glass

We investigate the Lévy glass, a mean-field spin-glass model with power-law distributed couplings characterized by a divergent second moment. By combining extensively many small couplings with a spare random backbone of strong bonds the model is intermediate between the Sherrington-Kirkpatrick and the Viana-Bray models. A truncated version where couplings smaller than some threshold ε are neglected can be studied within the cavity method developed for spin glasses on locally treelike random graphs. By performing the limit ε→0 in a well-defined way we calculate the thermodynamic functions within replica symmetry and determine the de Almeida-Thouless line in the presence of an external magnetic field. Contrary to previous findings we show that there is no replica-symmetric spin-glass phase. Moreover we determine the leading corrections to the ground-state energy within one-step replica symmetry breaking. The effects due to the breaking of replica symmetry appear to be small in accordance with the intuitive picture that a few strong bonds per spin reduce the degree of frustration in the system.

Stoichiometric model of the photosynthetic unit of Ectothiorhodospira halochloris

A stoichiometric model of the photosynthetic unit of Ectothiorhodospira halochloris has been obtained by means of scanning transmission electron microscope mass determination and mass mapping in conjunction with polyacrylamide gel electrophoresis. One reaction center, consisting of four single polypeptides, including one cytochrome, is surrounded by six identical light-harvesting complexes, each containing three polypeptides with 2:2:2 stoichiometry. This stoichiometric model was incorporated into the three-dimensional structure of the photosynthetic unit as derived from surface relief reconstructions of the two surfaces of shadowed membranes. The reaction center protrudes substantially from both membrane surfaces and has the cytochrome attached to the periplasmic face in a noncentrosymmetric fashion. The reaction center may assume various orientations within the photosynthetic complexes.

The yeast cell fusion protein Prm1p requires covalent dimerization to promote membrane fusion

Prm1p is a multipass membrane protein that promotes plasma membrane fusion during yeast mating. The mechanism by which Prm1p and other putative regulators of developmentally controlled cell-cell fusion events facilitate membrane fusion has remained largely elusive. Here, we report that Prm1p forms covalently linked homodimers. Covalent Prm1p dimer formation occurs via intermolecular disulfide bonds of two cysteines, Cys-120 and Cys-545. PRM1 mutants in which these cysteines have been substituted are fusion defective. These PRM1 mutants are normally expressed, retain homotypic interaction and can traffic to the fusion zone. Because prm1-C120S and prm1-C545S mutants can form covalent dimers when coexpressed with wild-type PRM1, an intermolecular C120-C545 disulfide linkage is inferred. Cys-120 is adjacent to a highly conserved hydrophobic domain. Mutation of a charged residue within this hydrophobic domain abrogates formation of covalent dimers, trafficking to the fusion zone, and fusion-promoting activity. The importance of intermolecular disulfide bonding informs models regarding the mechanism of Prm1-mediated cell-cell fusion.

Comment on' Superconducting transition in Nb nanowires fabricated using a focused-ion beam'

In a recent paper Tettamanzi et al (2009 Nanotechnology 20 465302) describe the fabrication of superconducting Nb nanowires using a focused-ion beam. They interpret their conductivity data in the framework of thermal and quantum phase slips below T(c). In the following we will argue that their analysis is inappropriate and incomplete, leading to contradictory results. Instead, we propose an interpretation of the data within an SN proximity model.

Asymptotics of work distributions in nonequilibrium systems

The asymptotic behavior of the work distribution in driven nonequilibrium systems is determined using the method of optimal fluctuations. For systems described by Langevin dynamics the corresponding Euler-Lagrange equation together with the appropriate boundary conditions and an equation for the leading pre-exponential factor are derived. The method is applied to three representative examples and the results are used to improve the accuracy of free-energy estimates based on the application of the Jarzynski equation.

Increased production of erythropoietin after application of antidiuretic hormone. A consequence of renal vasoconstriction?

The renal glycoprotein hormone erythropoietin (Epo) is the key element in the feedback control of the production of red blood cells (RBC) in bone marrow. Excess of antidiuretic hormone (ADH) increases the RBC mass by increasing the synthesis of Epo. The mechanism of the Epo stimulating effect of ADH is not fully understood. Rats were treated with ADH with or without prior injection of a V1a-receptor antagonist. Additional experiments were carried out by stimulating the V2-receptor by desmopressin (DDAVP). Epo level in plasma was doubled following injections of ADH. Blockade of the V1a-receptor completely abolished the Epo stimulating effect of ADH. Neither ADH alone nor the combined giving of V1a-antagonist and ADH had an influence on the glomerular filtration rate or the renal plasma flow. Therefore, the increased Epo synthesis after application of ADH cannot be explained by a constriction of renal blood vessels with consecutive ischemic hypoxia. There is rather a direct stimulation of Epo synthesis by ADH via its receptors. Since a selective stimulation of the V2-receptor by DDAVP did not increase to Epo level in plasma, the observed increase of Epo is mediated by the V1a-receptor.

Membrane lysis during biological membrane fusion: collateral damage by misregulated fusion machines

In the canonical model of membrane fusion, the integrity of the fusing membranes is never compromised, preserving the identity of fusing compartments. However, recent molecular simulations provided evidence for a pathway to fusion in which holes in the membrane evolve into a fusion pore. Additionally, two biological membrane fusion models-yeast cell mating and in vitro vacuole fusion-have shown that modifying the composition or altering the relative expression levels of membrane fusion complexes can result in membrane lysis. The convergence of these findings showing membrane integrity loss during biological membrane fusion suggests new mechanistic models for membrane fusion and the role of membrane fusion complexes.