Inflammatory molecular endotypes of nasal polyps derived from White and Japanese populations.

BACKGROUND: Emerging evidence suggests that chronic rhinosinusitis with nasal polyps (CRSwNP) is a highly heterogeneous disease with disparate inflammatory characteristics between different racial groups and geographies. Currently, little is known about possible underlying distinguishing factors between these inflammatory differences. OBJECTIVE: Our aim was to interrogate differences in CRSwNP disease between White/non-Asian patients and Japanese patients by using whole transcriptome and single-cell RNA gene expression profiling of nasal polyps (NPs). METHODS: We performed whole transcriptome RNA sequencing with endotype stratification of NPs from 8 White patients (residing in the United States) and 9 Japanese patients (residing in Japan). Reproducibility was confirmed by quantitative PCR in an independent validation set of 46 White and 31 Japanese patients. Single-cell RNA sequencing (scRNAseq) was used to stratify key cell types for contributory transcriptional signatures. RESULTS: Unsupervised clustering analysis identified 2 major endotypes that were present within both cohorts of patients with NPs and had previously been reported at the cytokine level: (1) type 2 endotype and (2) non-type 2 endotype. Importantly, there was a statistically significant difference in the proportion of these endotypes between these geographically distinct subgroups with NPs (P = .03). Droplet-based single-cell RNA sequencing further identified prominent type 2 inflammatory transcript expression: C-C motif chemokine ligand 13 (CCL13) and CCL18 in M2 macrophages, as well as cystatin SN (CST1) and CCL26 in basal, suprabasal, and secretory epithelial cells. CONCLUSION: NPs from both racial groups harbor the same 2 major endotypes, which we have determined to be present in differing ratios between each cohort with CRSwNP disease. Distinct inflammatory and epithelial cells contribute to the type 2 inflammatory profiles observed.

Proton TOCSY NMR relaxation rates quantitate protein side chain mobility in the Pin1 WW domain.

Protein side chain dynamics play a vital role in many biological processes, but differentiating mobile from rigid side chains remains a technical challenge in structural biology. Solution NMR spectroscopy is ideally suited for this but suffers from limited signal-to-noise, signal overlap, and a need for fractional 13C or 2H labeling. Here we introduce a simple strategy measuring initial 1H relaxation rates during a 1H TOCSY sequence like DIPSI-2, which can be appended to the beginning of any multi-dimensional NMR sequence that begins on 1H. The TOCSY RF field compels all 1H atoms to behave similarly under the influence of strong coupling and rotating frame cross-relaxation, so that differences in relaxation rates are due primarily to side chain mobility. We apply the scheme to a thermostable mutant Pin1 WW domain and demonstrate that the observed 1H relaxation rates correlate well with two independent NMR measures of side-chain dynamics, cross-correlated 13C relaxation rates in 13CßH2 methylene groups and maximum observable 3J couplings sensitive to the χ1 side chain dihedral angle (3JHα,Hß, 3JN,Hß, and 3JCO,Hß). The most restricted side chains belong to Trp26 and Asn40, which are closely packed to constitute the folding center of the WW domain. None of the other conserved aromatic residues is as immobile as the first tryptophan side chain of the WW domain. The proposed 1H relaxation methodology should make it relatively easy to measure side chain dynamics on uniformly 15N- or 13C-labeled proteins, so long as chemical shift assignments are obtainable.

Deciphering the activation and recognition mechanisms of Staphylococcus aureus response regulator ArlR.

Staphylococcus aureus ArlRS is a key two-component regulatory system necessary for adhesion, biofilm formation, and virulence. The response regulator ArlR consists of a C-terminal DNA-binding effector domain and an N-terminal receiver domain that is phosphorylated by ArlS, the cognate transmembrane sensor histidine kinase. We demonstrate that the receiver domain of ArlR adopts the canonical α5ß5 response regulator assembly, which dimerizes upon activation, using beryllium trifluoride as an aspartate phosphorylation mimic. Activated ArlR recognizes a 20-bp imperfect inverted repeat sequence in the ica operon, which is involved in intercellular adhesion polysaccharide production. Crystal structures of the inactive and activated forms reveal that activation induces a significant conformational change in the ß4-α4 and ß5-α5-connecting loops, in which the α4 and α5 helices constitute the homodimerization interface. Crystal structures of the DNA-binding ArlR effector domain indicate that it is able to dimerize via a non-canonical ß1-ß2 hairpin domain swapping, raising the possibility of a new mechanism for signal transduction from the receiver domain to effector domain. Taken together, the current study provides structural insights into the activation of ArlR and its recognition, adding to the diversity of response regulation mechanisms that may inspire novel antimicrobial strategies specifically targeting Staphylococcus.

Minimally invasive carpal tunnel decompression using the KnifeLight: How I Do It.

BACKGROUND: Carpal tunnel decompression is commonly performed open or endoscopically. Carpal tunnel release using the KnifeLight instrument (Stryker, Kalamazoo, MI) is an alternative method established in 2000. METHOD: The instrument has a cutting blade placed between two blunt flat tips with an integrated light source which helps to locate the tool blade by transillumination through the tissues. The instrument is inserted into an opening made in the wrist crease and transverse carpal ligament and used to divide the ligament. CONCLUSION: This is a simple, efficient, and reproducible alternative for carpal tunnel decompression.

The international sinonasal microbiome study: A multicentre, multinational characterization of sinonasal bacterial ecology.

The sinonasal microbiome remains poorly defined, with our current knowledge based on a few cohort studies whose findings are inconsistent. Furthermore, the variability of the sinus microbiome across geographical divides remains unexplored. We characterize the sinonasal microbiome and its geographical variations in both health and disease using 16S rRNA gene sequencing of 410 individuals from across the world. Although the sinus microbial ecology is highly variable between individuals, we identify a core microbiome comprised of Corynebacterium, Staphylococcus, Streptococcus, Haemophilus and Moraxella species in both healthy and chronic rhinosinusitis (CRS) cohorts. Corynebacterium (mean relative abundance = 44.02%) and Staphylococcus (mean relative abundance = 27.34%) appear particularly dominant in the majority of patients sampled. Amongst patients suffering from CRS with nasal polyps, a statistically significant reduction in relative abundance of Corynebacterium (40.29% vs 50.43%; P = .02) was identified. Despite some measured differences in microbiome composition and diversity between some of the participating centres in our cohort, these differences would not alter the general pattern of core organisms described. Nevertheless, atypical or unusual organisms reported in short-read amplicon sequencing studies and that are not part of the core microbiome should be interpreted with caution. The delineation of the sinonasal microbiome and standardized methodology described within our study will enable further characterization and translational application of the sinus microbiota.

Structural Changes Induced by the Binding of the Calcium Desensitizer W7 to Cardiac Troponin.

Compounds that directly modulate the affinity of the thin filament calcium regulatory proteins in cardiac muscle have potential for treating heart disease. A recent "proof of concept" study showed that the desensitizer W7 can correct hyper-calcium-sensitive sarcomeres from RCM R193H inhibitory subunit troponin I (cTnI) transgenic mice. We have determined the high-resolution nuclear magnetic resonance solution structure of W7 bound to the regulatory domain of calcium binding subunit troponin C (cNTnC)-cTnI cChimera designed to represent the key aspects of the cTnC-cTnI interface. The structure shows that W7 does not perturb the overall structure of the cTnC-cTnI interface, with the helical structure and position of the cTnI switch region remaining intact upon W7 binding. The naphthalene ring of W7 sits in the hydrophobic pocket created by the cNTnC-cTnI switch peptide interface, while the positively charged amine tail extends into the solvent. The positively charged tail of W7 is in the proximity of Arg147 of the cTnI switch region, supporting the suggestion that electrostatic repulsion is an aspect underlying the mechanism of desensitization. Ser84 (replacing the unique Cys84 in cTnC reported to make a reversible covalent bond with levosimendan) also contacts W7.

Identification and Characterization of Novel Receptor-Interacting Serine/Threonine-Protein Kinase 2 Inhibitors Using Structural Similarity Analysis.

Receptor-interacting protein kinase 2 (RIP2 or RICK, herein referred to as RIPK2) is linked to the pathogen pathway that activates nuclear factor κ-light-chain-enhancer of activated B cells (NFκB) and autophagic activation. Using molecular modeling (docking) and chemoinformatics analyses, we used the RIPK2/ponatinib crystal structure and searched in chemical databases for small molecules exerting binding interactions similar to those exerted by ponatinib. The identified RIPK2 inhibitors potently inhibited the proliferation of cancer cells by > 70% and also inhibited NFκB activity. More importantly, in vivo inhibition of intestinal and lung inflammation rodent models suggests effectiveness to resolve inflammation with low toxicity to the animals. Thus, our identified RIPK2 inhibitor may offer possible therapeutic control of inflammation in diseases such as inflammatory bowel disease, asthma, cystic fibrosis, primary sclerosing cholangitis, and pancreatitis.

Sinonasal debridement versus no debridement for the postoperative care of patients undergoing endoscopic sinus surgery.

BACKGROUND: Endoscopic sinus surgery (ESS) is often recommended for symptomatic patients with recurrent acute or chronic rhinosinusitis who have failed conservative treatment. Postoperative care has been felt to be critical for both maintaining the surgical patency of the operated sinuses and improving patient symptoms. Debridement of the sinonasal cavities is one such postoperative care measure that has frequently been studied in the literature, often with conflicting conclusions. OBJECTIVES: To assess the effects of postoperative sinonasal debridement versus no debridement following endoscopic sinus surgery. SEARCH METHODS: The Cochrane ENT Information Specialist searched the ENT Trials Register; Central Register of Controlled Trials (CENTRAL, via the Cochrane Register of Studies); PubMed; EMBASE; Web of Science; ClinicalTrials.gov; ICTRP and additional sources for published and unpublished trials. The date of the search was 21 May 2018. SELECTION CRITERIA: Randomised controlled trials comparing postoperative nasal debridement versus no debridement in adult patients with recurrent acute or chronic rhinosinusitis undergoing endoscopic sinus surgery. We included studies in which the patients acted as self-controls (i.e. one side of the nose underwent debridement and the other side did not) only for the secondary endoscopy outcomes. DATA COLLECTION AND ANALYSIS: We used the standard methodological procedures expected by Cochrane. Our primary outcome measures were: health-related quality of life, disease severity (patient-reported symptom scores) and significant adverse effects (bleeding requiring intervention, severe pain, iatrogenic injury). Secondary outcomes were: postoperative endoscopic appearance of the sinonasal surgical cavities (endoscopic scores), recorded use of postoperative medical treatment and rate of revision surgery. We used GRADE to assess the quality of the evidence for each outcome; this is indicated in italics. MAIN RESULTS: We included four studies (152 participants), with a follow-up duration ranging from three months to 12 months. In two studies patients acted as self-controls, i.e. one side of the nose underwent debridement and the other side did not ('split-nose' studies). The risk of bias in all studies was high, mostly due to the inability to blind the patients to the debridement procedure.Primary outcomesDisease-specific health-related quality of life scoresOnly one study (58 participants) provided data for disease-specific health-related quality of life. At six months follow-up, lower disease-specific health-related quality of life scores, measured using the Sino-Nasal Outcome Test-22 (SNOT-22, range 0 to 110), were noted in the debridement group but the difference was not statistically significant (9.7 in the debridement group versus 10.3 in the control group, P = 0.47) (low-quality evidence).Disease severity (patient-reported symptom score)Only one study (60 participants) provided data for disease severity measured by visual analogue scale (VAS) score. No significant differences in total symptom score were observed between groups postoperatively (low-quality evidence).Significant adverse effectsSignificant adverse effects related to the debridement procedure were not reported in any of the included studies, however it is not clear whether data regarding adverse effects were not collected or if none were indeed observed in any of the included studies.Secondary outcomesAll four studies assessed thepostoperative endoscopic appearance of the sinonasal cavities using the Lund-Kennedy score (range 0 to 10). A pooled analysis of endoscopic scores in the two non 'split-nose' studies revealed better endoscopic scores in the debridement group, however this was not a statistically significant difference (mean difference -0.31, 95% confidence interval (CI) -1.35 to 0.72; I² = 0%; two studies; 118 participants) (low-quality evidence). A sub-analysis of the adhesion formation component of the endoscopic score was available for all four studies and revealed a significantly lower adhesion rate in the debridement group (risk ratio 0.43, 95% CI 0.28 to 0.68; I² = 29%; four studies; 152 participants). Analysis of the number needed to treat to benefit revealed that for every three patients undergoing debridement, the endoscopic score would be decreased by one point in one patient. For every five patients undergoing debridement adhesion formation would be prevented in one patient.Use of postoperative medical treatment was reported in all studies, all of which recommended nasal douching. Steroids (systemic or nasal) were administered in two studies. However, the data were very limited and heterogeneous, therefore we could not analyse the impact of concomitant postoperative medical treatment.The rate of revision surgery was not reported in any of the included studies, however it is not clear whether these data were not recorded or if there were no revision surgeries in any of the included studies. AUTHORS' CONCLUSIONS: We are uncertain about the effects of postoperative sinonasal debridement due to high risk of bias in the included studies and the low quality of the evidence. Sinonasal debridement may make little or no difference to disease-specific health-related quality of life or disease severity. Low-quality evidence suggests that postoperative debridement is associated with a significantly lower risk of adhesions at three months follow-up. Whether this has any impact on longer-term outcomes is unknown.

Evidence for altered levels of IgD in the nasal airway mucosa of patients with chronic rhinosinusitis.

BACKGROUND: IgD is an enigmatic antibody isotype best known when coexpressed with IgM on naive B cells. However, increased soluble IgD (sIgD) levels and increased IgD+IgM- B-cell populations have been described in the human upper respiratory mucosa. OBJECTIVE: We assessed whether levels of sIgD and IgD+ B cell counts are altered in nasal tissue from patients with chronic rhinosinusitis (CRS). We further characterized IgD+ B-cell populations and explored clinical and local inflammatory factors associated with tissue sIgD levels. METHODS: sIgD levels were measured by means of ELISA in nasal tissues, nasal lavage fluid, sera, and supernatants of dissociated nasal tissues. IgD+ cells were identified by using immunofluorescence and flow cytometry. Inflammatory mediator levels in tissues were assessed by using real-time PCR and multiplex immunoassays. Bacterial cultures from the middle meatus were performed. Underlying medical history and medicine use were obtained from medical records. RESULTS: sIgD levels and numbers of IgD+ cells were significantly increased in uncinate tissue (UT) of patients with chronic rhinosinusitis without nasal polyps (CRSsNP) compared with that of control subjects (4-fold, P < .05). IgD+ cells were densely scattered in the periglandular regions of UT from patients with CRSsNP. We also found that IgD+CD19+CD38bright plasmablast numbers were significantly increased in tissues from patients with CRSsNP compared with control tissues (P < .05). Among numerous factors tested, IL-2 levels were increased in UT from patients with CRSsNP and were positively correlated with tissue IgD levels. Additionally, supernatants of IL-2-stimulated dissociated tissue from patients with CRSsNP had significantly increased sIgD levels compared with those in IL-2-stimulated dissociated control tissue ex vivo (P < .05). Tissue from patients with CRS with preoperative antibiotic use or those with pathogenic bacteria showed higher IgD levels compared with tissue from patients without these variables (P < .05). CONCLUSION: sIgD levels and IgD+CD19+CD38bright plasmablast counts were increased in nasal tissue of patients with CRSsNP. IgD levels were associated with increased IL-2 levels and the presence of pathogenic bacteria. These findings suggest that IgD might contribute to enhancement mucosal immunity or inflammation or respond to bacterial infections in patients with CRS, especially CRSsNP.

Stereoselective Deuteration in Aspartate, Asparagine, Lysine, and Methionine Amino Acid Residues Using Fumarate as a Carbon Source for Escherichia coli in D2O.

Perdeuteration with selective 1H,13C-enrichment of methyl groups has enabled solution NMR studies of large (>30 kDa) protein systems. However, we propose that for all non-methyl positions, only magnetization originating from 1H-12C groups is sufficiently long-lived, and it can be transferred via through-space NOEs to slowly relaxing 1H-15N or 1H-13C methyl groups to achieve multidimensional solution NMR. We demonstrate stereoselective 1H,12C-labeling by adding relatively inexpensive unlabeled carbon sources to Escherichia coli growth media in D2O. Using our model system, a mutant WW domain from human Pin1, we compare deuteration patterns in 19 amino acids (all except cysteine). Protein grown using glucose as the sole carbon source had high levels of protonation in aromatic rings and the Hß positions of serine and tryptophan. In contrast, using our FROMP media (fumarate, rhamnose, oxalate, malonate, pyruvate), stereoselective protonation of Hß2 with deuteration at Hα and Hß3 was achieved in Asp, Asn, Lys, and Met residues. In solution NMR, stereospecific chemical shift assignments for Hß are typically obtained in conjunction with χ1 dihedral angle determinations using 3-bond J-coupling (3JN-Hß, 3JCO-Hß, 3JHα-Hß) experiments. However, due to motional averaging, the assumption of a pure rotameric state can yield incorrect χ1 dihedral angles with incorrect stereospecific assignments. This was the case for three residues in the Pin1 WW domain (Lys28, Met30, and Asn44). Thus, stereoselective 1H,12C-labeling will be useful not only for NMR studies of large protein systems, but also for determining side chain rotamers and dynamics in any protein system.

Selective expansion of human regulatory T cells in nasal polyps, and not adjacent tissue microenvironments, in individual patients exposed to steroids.

Severe forms of chronic rhinosinusitis (CRS), a common upper airway inflammatory disorder, are associated with nasal polyps (NPs). NP disease is ameliorated by glucocorticoid (GC) treatment, whose cellular effects are poorly understood. We therefore assessed the influence of GC therapy on NPs in CRS patients, focusing on regulatory T (Treg) cells. Treg cell populations were analyzed by flow cytometry in NPs and control tissues from GC-treated CRS patients and controls. After GC exposure, selective expansion of Treg cells was seen within NPs, and not blood or adjacent ethmoid tissues. To confirm direct GC effects, NPs from the same patients were biopsied prior to, and following, 1week of oral GC exposure. Direct expansion of Tregs into the same NP bed was detected in 4/4 CRS patients following GC exposure. Treg cell spikes into NPs were secondary to cellular recruitment given limited Ki67 expression within these regulatory cells. Chemokine gene expression profiling identified several chemokines, notably CCL4, induced within NPs upon GC treatment. Neutralization of chemokine receptor/ligand interactions using CCR4 small molecule antagonists reduced Treg migration towards GC-treated NPs in an ex vivo migration assay. Our findings suggest that the common use of GCs in the treatment of NP disease leads to recruitment of Treg cells from peripheral sites into NP tissues, which may be critical to the anti-inflammatory effect of GCs. Mechanistically Treg expansion appears to be conferred, in part, by chemokine receptor/ligand interactions induced following corticosteroid therapy.

Enhanced potency of bivalent small molecule gp41 inhibitors.

Low molecular weight peptidomimetic inhibitors with hydrophobic pocket binding properties and moderate fusion inhibitory activity against HIV-1 gp41-mediated cell fusion were elaborated by increasing the available surface area for interacting with the heptad repeat-1 (HR1) coiled coil on gp41. Two types of modifications were tested: 1) increasing the overall hydrophobicity of the molecules with an extension that could interact in the HR1 groove, and 2) forming symmetrical dimers with two peptidomimetic motifs that could potentially interact simultaneously in two hydrophobic pockets on the HR1 trimer. The latter approach was more successful, yielding 40-60times improved potency against HIV fusion over the monomers. Biophysical characterization, including equilibrium binding studies by fluorescence and kinetic analysis by Surface Plasmon Resonance, revealed that inhibitor potency was better correlated to off-rates than to binding affinity. Binding and kinetic data could be fit to a model of bidentate interaction of dimers with the HR1 trimer as an explanation for the slow off-rate, albeit with minimal cooperativity due to the highly flexible ligand structures. The strong cooperativity observed in fusion inhibitory activity of the dimers implied accentuated potency due to the transient nature of the targeted intermediate. Optimization of monomer, dimer or higher order structures has the potential to lead to highly potent non-peptide fusion inhibitors by targeting multiple hydrophobic pockets.

The cardiac-specific N-terminal region of troponin I positions the regulatory domain of troponin C.

The cardiac isoform of troponin I (cTnI) has a unique 31-residue N-terminal region that binds cardiac troponin C (cTnC) to increase the calcium sensitivity of the sarcomere. The interaction can be abolished by cTnI phosphorylation at Ser22 and Ser23, an important mechanism for regulating cardiac contractility. cTnC contains two EF-hand domains (the N and C domain of cTnC, cNTnC and cCTnC) connected by a flexible linker. Calcium binding to either domain favors an "open" conformation, exposing a large hydrophobic surface that is stabilized by target binding, cTnI[148-158] for cNTnC and cTnI[39-60] for cCTnC. We used multinuclear multidimensional solution NMR spectroscopy to study cTnI[1-73] in complex with cTnC. cTnI[39-60] binds to the hydrophobic face of cCTnC, stabilizing an alpha helix in cTnI[41-67] and a type VIII turn in cTnI[38-41]. In contrast, cTnI[1-37] remains disordered, although cTnI[19-37] is electrostatically tethered to the negatively charged surface of cNTnC (opposite its hydrophobic surface). The interaction does not directly affect the calcium binding affinity of cNTnC. However, it does fix the positioning of cNTnC relative to the rest of the troponin complex, similar to what was previously observed in an X-ray structure [Takeda S, et al. (2003) Nature 424(6944):35-41]. Domain positioning impacts the effective concentration of cTnI[148-158] presented to cNTnC, and this is how cTnI[19-37] indirectly modulates the calcium affinity of cNTnC within the context of the cardiac thin filament. Phosphorylation of cTnI at Ser22/23 disrupts domain positioning, explaining how it impacts many other cardiac regulatory mechanisms, like the Frank-Starling law of the heart.

Structural and functional insight into TAF1-TAF7, a subcomplex of transcription factor II D.

Transcription factor II D (TFIID) is a multiprotein complex that nucleates formation of the basal transcription machinery. TATA binding protein-associated factors 1 and 7 (TAF1 and TAF7), two subunits of TFIID, are integral to the regulation of eukaryotic transcription initiation and play key roles in preinitiation complex (PIC) assembly. Current models suggest that TAF7 acts as a dissociable inhibitor of TAF1 histone acetyltransferase activity and that this event ensures appropriate assembly of the RNA polymerase II-mediated PIC before transcriptional initiation. Here, we report the 3D structure of a complex of yeast TAF1 with TAF7 at 2.9 Å resolution. The structure displays novel architecture and is characterized by a large predominantly hydrophobic heterodimer interface and extensive cofolding of TAF subunits. There are no obvious similarities between TAF1 and known histone acetyltransferases. Instead, the surface of the TAF1-TAF7 complex contains two prominent conserved surface pockets, one of which binds selectively to an inhibitory trimethylated histone H3 mark on Lys27 in a manner that is also regulated by phosphorylation at the neighboring H3 serine. Our findings could point toward novel roles for the TAF1-TAF7 complex in regulation of PIC assembly via reading epigenetic histone marks.

Structures reveal details of small molecule binding to cardiac troponin.

In cardiac and skeletal muscle, the troponin complex turns muscle contraction on and off in a calcium-dependent manner. Many small molecules are known to bind to the troponin complex to modulate its calcium binding affinity, and this may be useful in a broad range of conditions in which striated muscle function is compromised, such as congestive heart failure. As a tool for developing drugs specific for the cardiac isoform of troponin, we have designed a chimeric construct (cChimera) consisting of the regulatory N-terminal domain of cardiac troponin C (cNTnC) fused to the switch region of cardiac troponin I (cTnI), mimicking the key binding event that turns on muscle contraction. We demonstrate by solution NMR spectroscopy that cChimera faithfully reproduces the native interface between cTnI and cNTnC. We determined that small molecules based on diphenylamine can bind to cChimera with a KD as low as 10µM. Solution NMR structures show that minimal structural perturbations in cChimera are needed to accommodate 3-methyldiphenylamine (3-mDPA), which is probably why it binds with higher affinity than previously studied compounds like bepridil, despite its significantly smaller size. The unsubstituted aromatic ring of 3-mDPA binds to an inner hydrophobic pocket adjacent to the central beta sheet of cNTnC. However, the methyl-substituted ring is able to bind in two different orientations, either inserting into the cNTnC-cTnI interface or "flipping out" to form contacts primarily with helix C of cNTnC. Our work suggests that preservation of the native interaction between cNTnC and cTnI is key to the development of a high affinity cardiac troponin-specific drug.

Dementia resulting from expansion of basilar artery aneurysm: two case reports and a review of the literature.

BACKGROUND: Dementia places a large burden on the economy, with financial and emotional costs incurred by patients, caregivers and the health sector. METHODS AND RESULTS: We report the first published case series of giant basilar aneurysm leading to progressive cognitive and functional decline. We review the literature regarding giant aneurysms and their association with dementia and the possible underlying pathophysiological mechanism. CONCLUSIONS: This report highlights a number of therapeutic considerations when determining the best management strategy for these difficult lesions.

The Distance of the Common Peroneal Nerve to the Posterolateral Structures of the Knee.

BACKGROUND: The common peroneal nerve (CPN) is an important structure of the lower limb and is at risk of injury during total knee arthroplasty. The aim of this study was to use a tibial reference system to determine the position of the CPN relative to the knee center and popliteus. METHODS: Two hundred consecutive knee magnetic resonance images at the level of a standard tibial arthroplasty cut were evaluated for (1) distance of the CPN from the posterolateral capsule; (2) angle of the CPN from the center of the tibial anteroposterior axis; and (3) location of CPN with respect to the popliteus. RESULTS: The mean distance between the CPN and the posterolateral joint capsule was 11.9 mm (range, 4.7-22.13 mm), which correlated positively with the medial-lateral axis of the tibia (Pearson correlation, 0.157; P = .026) and negatively with the angle of the nerve from the midline (Pearson correlation, -0.237, P = .001). The mean angle of the nerve from the midline was 42.2° (range, 25.0°-64.0°). In 116 knees (58%), the CPN was in line with the popliteus from the center of the knee, in 69 knees (34.5%) the CPN was lateral to the popliteus, and in 15 knees (7.5%), the CPN was medial to the popliteus. A danger zone was identified as between 29.95° and 54.57° from the anteroposterior axis. CONCLUSION: The CPN is at risk during total knee arthroplasty. This study describes a method to help predict the location of the CPN intraoperatively and therefore avoid direct injury.

Management of rhinosinusitis during pregnancy: systematic review and expert panel recommendations.

BACKGROUND: Management of rhinosinusitis during pregnancy requires special considerations. OBJECTIVES: 1. Conduct a systematic literature review for acute and chronic rhinosinusitis (CRS) management during pregnancy. 2. Make evidence-based recommendations. METHODS: The systematic review was conducted using MEDLINE and EMBASE databases and relevant search terms. Title, abstract and full manuscript review were conducted by two authors independently. A multispecialty panel with expertise in management of Rhinological disorders, Allergy-Immunology, and Obstetrics-Gynecology was invited to review the systematic review. Recommendations were sought on use of following for CRS management during pregnancy: oral corticosteroids; antibiotics; leukotrienes; topical corticosteroid spray/irrigations/drops; aspirin desensitization; elective surgery for CRS with polyps prior to planned pregnancy; vaginal birth versus planned Caesarian for skull base erosions/ prior CSF rhinorrhea. RESULTS: Eighty-eight manuscripts underwent full review after screening 3052 abstracts. No relevant level 1, 2, or 3 studies were found. Expert panel recommendations for rhinosinusitis management during pregnancy included continuing nasal corticosteroid sprays for CRS maintenance, using pregnancy-safe antibiotics for acute rhinosinusitis and CRS exacerbations, and discontinuing aspirin desensitization for aspirin exacerbated respiratory disease. The manuscript presents detailed recommendations. CONCLUSIONS: The lack of evidence pertinent to managing rhinosinusitis during pregnancy warrants future trials. Expert recommendations constitute the current best available evidence.

Combining a PagP fusion protein system with nickel ion-catalyzed cleavage to produce intrinsically disordered proteins in E. coli.

Many proteins contain intrinsically disordered regions that are highly solvent-exposed and susceptible to post-translational modifications. Studying these protein segments is critical to understanding their physiologic regulation, but proteolytic degradation can make them difficult to express and purify. We have designed a new protein expression vector that fuses the target protein to the N-terminus of the integral membrane protein, PagP. The two proteins are connected by a short linker containing the sequence SRHW, previously shown to be optimal for nickel ion-catalyzed cleavage. The methodology is demonstrated for an intrinsically disordered segment of cardiac troponin I. cTnI[135-209]-SRHW-PagP-His6 fusion protein was overexpressed in Escherichia coli, accumulating in insoluble inclusion bodies. The protein was solubilized, purified using nickel affinity chromatography, and then cleaved with 0.5mM NiSO4 at pH 9.0 and 45 °C, all in 6M guanidine-HCl. Nickel ion-catalyzed peptide bond hydrolysis is an effective chemical cleavage technique under denaturing conditions that preclude the use of proteases. Moreover, nickel-catalyzed cleavage is more specific than the most commonly used agent, cyanogen bromide, which cleaves C-terminal to methionine residues. We were able to produce 15 mg of purified cTnI[135-209] from 1L of M9 minimal media using this protocol. The methodology is more generally applicable to the production of intrinsically disordered protein segments.