Deciphering Isomers with a Multiple Reaction Monitoring Method for the Complete Detectable O-Glycan Repertoire of the Candidate Therapeutic, Lubricin.

Glycosylation is a fundamental post-translational modification, occurring on half of all proteins. Despite its significance, our understanding is limited, in part due to the inherent difficulty in studying these branched, multi-isomer structures. Accessible, detailed, and quantifiable methods for studying glycans, particularly O-glycans, are needed. Here we take a multiple reaction monitoring (MRM) approach to differentiate and relatively quantify all detectable glycans, including isomers, on the heavily O-glycosylated protein lubricin. Lubricin (proteoglycan 4) is essential for lubrication of the joint and eye. Given the therapeutic potential of lubricin, it is essential to understand its O-glycan repertoire in biological and recombinantly produced samples. O-Glycans were released by reductive ß-elimination and defined, showing a range of 26 neutral, sulfated, sialylated, and both sulfated and sialylated core 1 (Galß1-3GalNAcα1-) and core 2 (Galß1-3(GlcNAcß1-6)GalNAcα1-) structures. Isomer-specific MRM transitions allowed effective differentiation of neutral glycan isomers as well as sulfated isomeric structures, where the sulfate was retained on the fragment ions. This strategy was not as effective with labile sialylated structures; instead, it was observed that the optimal collision energy for the m/z 290.1 sialic acid B-fragment differed consistently between sialic acid isomers, allowing differentiation between isomers when fragmentation spectra were insufficient. This approach was also effective for purchased Neu5Acα2-3Galß1-4Glc and Neu5Acα2-6Galß1-4Glc and for Neu5Acα2-3Galß1-4GlcNAc and Neu5Acα2-6Galß1-4GlcNAc linkage isomers with the Neu5Acα2-6 consistently requiring more energy for optimal generation of the m/z 290.1 fragment. Overall, this method provides an effective and easily accessible approach for the quantification and annotation of complex released O-glycan samples.

Separation of Sialylated Glycan Isomers by Differential Mobility Spectrometry.

Mass spectrometry has proven itself to be an important technology for characterizing intact glycoproteins, glycopeptides, and released glycans. However, these molecules often present significant challenges during analysis. For example, glycans of identical molecular weights can be present in many isomeric forms, with one form having dramatically more biological activity than the others. Discriminating among these isomeric forms using mass spectrometry alone can be daunting, which is why orthogonal techniques, such as ion mobility spectrometry, have been explored. Here, we demonstrate the use of differential mobility spectrometry (DMS) to separate isomeric glycans differing only in the linkages of sialic acid groups (e.g., α 2,3 versus α 2,6). This ability extends from a small trisaccharide species to larger biantennary systems and is driven, in part, by the role of intramolecular solvation of the charge site(s) on these ions within the DMS environment.

Adolescent Male Circumcision for HIV Prevention in High Priority Countries: Opportunities for Improvement.

Global experts recognize the need to transform conventional models of healthcare to create adolescent responsive health systems. As countries near 80% coverage of voluntary medical male circumcision (VMMC) for those aged 15-49 years, prioritization of younger men becomes critical to VMMC sustainability. This special supplement reporting 9 studies focusing on adolescent VMMC programming and services comes at a critical time. Eight articles report how well adolescents are reached with the World Health Organization's minimum package for comprehensive human immunodeficiency virus (HIV) prevention in South Africa, Zimbabwe, and Tanzania, analyzing motivation, counseling, wound healing, parental involvement, female peer support, quality of in-service communication, and providers' perceptions, and one presents models for achieving high VMMC coverage by 2021. One important finding is that adolescent boys, especially the youngest, experience gaps in their comprehension of key elements in the World Health Organization's minimum package. Although parents, counselors, and providers are involved and supportive, they are inadequately prepared to counsel youth, partly owing to discomfort with adolescent sexuality. At the country level, deliberately prioritizing young adolescents (aged 10-14 years) is likely to achieve national coverage targets more quickly and cost-effectively than continuing to focus on older, harder-to-reach men. The studies in this supplement point to areas where VMMC programs are achieving successes and they reveal areas for improvement. Given that prioritizing adolescents will be the best means of achieving sustainable VMMC for HIV prevention for the foreseeable future, applying the lessons learned here will increase the effectiveness of VMMC programs.

A never-before opportunity to strengthen investment and action on adolescent contraception, and what we must do to make full use of it.

BACKGROUND: Increasingly, the health and rights of adolescents are being recognized and prioritized on the global agenda. This presents us with a "never-before" opportunity to address adolescent contraception. This is timely, as there are enormous numbers of adolescents who are currently unable to obtain and use contraceptives. From research evidence and programmatic experience, it is clear that we need to do things differently to meet their needs/fulfil their rights. MAIN BODY: In this commentary, we call for action in several key areas to address adolescents' persistent inability to obtain and use contraceptives. We must move away from one-size-fits-all approaches, from a 'condoms-only' mind set, from separate services for adolescents, from ignoring the appeal of pharmacies and shops, and from one-off-training to make health workers adolescent friendly. Our efforts to expand access to quality contraceptive services to adolescents must be combined with efforts to build their desire and ability to use them, and to do so consistently. In order for these changes to be made, action must be taken on several levels. This includes the formulation of sound national policies and strategies, robust programme implementation with monitoring, regular programmatic reviews, and implementation research. Further, high-quality collection, analysis, and dissemination of data must underlie all of our efforts. As we move ahead, we must also recognize and draw lessons from positive examples of large scale and sustained programmes in countries that have led the way in increasing contraceptive use by adolescents. CONCLUSION: This unprecedented moment in history gives us a real opportunity to bring about transformational change, particularly when there is so much at stake.

Assessment of SRM, MRM(3) , and DIA for the targeted analysis of phosphorylation dynamics in non-small cell lung cancer.

Hypothesis-driven MS-based targeted proteomics has gained great popularity in a relatively short timespan. Next to the widely established selected reaction monitoring (SRM) workflow, data-independent acquisition (DIA), also referred to as sequential window acquisition of all theoretical spectra (SWATH) was introduced as a high-throughput targeted proteomics method. DIA facilitates increased proteome coverage, however, does not yet reach the sensitivity obtained with SRM. Therefore, a well-informed method selection is crucial for designing a successful targeted proteomics experiment. This is especially the case when targeting less conventional peptides such as those that contain PTMs, as these peptides do not always adhere to the optimal fragmentation considerations for targeted assays. Here, we provide insight into the performance of DIA, SRM, and MRM cubed (MRM(3) ) in the analysis of phosphorylation dynamics throughout the phosphoinositide 3-kinase mechanistic target of rapamycin (PI3K-mTOR) and mitogen-activated protein kinase (MAPK) signaling network. We observe indeed that DIA is less sensitive when compared to SRM, however demonstrates increased flexibility, by postanalysis selection of alternative phosphopeptide precursors. Additionally, we demonstrate the added benefit of MRM(3) , allowing the quantification of two poorly accessible phosphosites. In total, targeted proteomics enabled the quantification of 42 PI3K-mTOR and MAPK phosphosites, gaining a so far unachieved in-depth view mTOR signaling events linked to tyrosine kinase inhibitor resistance in non-small cell lung cancer.

Comparing Multiple Reaction Monitoring and Sequential Window Acquisition of All Theoretical Mass Spectra for the Relative Quantification of Barley Gluten in Selectively Bred Barley Lines.

Celiac disease (CD) is a disease of the small intestine that occurs in genetically susceptible subjects triggered by the ingestion of cereal gluten proteins for which the only treatment is strict adherence to a life-long gluten-free diet. Barley contains four gluten protein families, and the existence of barley genotypes that do not accumulate the B-, C-, and D-hordeins paved the way for the development of an ultralow gluten phenotype. Using conventional breeding strategies, three null mutations behaving as recessive alleles were combined to create a hordein triple-null barley variety. Proteomics has become an invaluable tool for characterization and quantification of the protein complement of cereal grains. In this study multiple reaction monitoring (MRM) mass spectrometry, viewed as the gold standard for peptide quantification, was compared to the data-independent acquisition strategy known as SWATH-MS (sequential window acquisition of all theoretical mass spectra). SWATH-MS was comparable (p < 0.001) to MRM-MS for 32/33 peptides assessed across the four families of hordeins (gluten) in eight barley lines. The results of SWATH-MS analysis further confirmed the absence of the B-, C-, and D-hordeins in the triple-null barley line and showed significantly reduced levels ranging from <1% to 16% relative to wild-type (WT) cv Sloop for the minor γ-hordein class. SWATH-MS represents a valuable tool for quantitative proteomics based on its ability to generate reproducible data comparable with MRM-MS, but has the added benefits of allowing reinterrogation of data to improve analytical performance, ask new questions, and in this case perform quantification of trypsin-resistant proteins (C-hordeins) through analysis of their semi- or nontryptic fragments.

Selected reaction monitoring to differentiate and relatively quantitate isomers of sulfated and unsulfated core 1 O-glycans from salivary MUC7 protein in rheumatoid arthritis.

Rheumatoid arthritis is a common and debilitating systemic inflammatory condition affecting up to 1% of the world's population. This study aimed to investigate the immunological significance of O-glycans in chronic arthritis at a local and systemic level. O-Glycans released from synovial glycoproteins during acute and chronic arthritic conditions were compared and immune-reactive glycans identified. The sulfated core 1 O-glycan (Galß1-3GalNAcol) was immune reactive, showing a different isomeric profile in the two conditions. From acute reactive arthritis, three isomers could be sequenced, but in patients with chronic rheumatoid arthritis, only a single 3-Gal sulfate-linked isomer could be identified. The systemic significance of this glycan epitope was investigated using the salivary mucin MUC7 in patients with rheumatoid arthritis and normal controls. To analyze this low abundance glycan, a selected reaction monitoring (SRM) method was developed to differentiate and relatively quantitate the core 1 O-glycan and the sulfated core 1 O-glycan Gal- and GalNAc-linked isomers. The acquisition of highly sensitive full scan linear ion trap MS/MS spectra in addition to quantitative SRM data allowed the 3- and 6-linked Gal isomers to be differentiated. The method was used to relatively quantitate the core 1 glycans from MUC7 to identify any systemic changes in this carbohydrate epitope. A statistically significant increase in sulfation was identified in salivary MUC7 from rheumatoid arthritis patients. This suggests a potential role for this epitope in chronic inflammation. This study was able to develop an SRM approach to specifically identify and relatively quantitate sulfated core 1 isomers and the unsulfated structure. The expansion of this method may afford an avenue for the high throughput investigation of O-glycans.

A multiplex protein panel assay for severity prediction and outcome prognosis in patients with COVID-19: An observational multi-cohort study.

Background: Global healthcare systems continue to be challenged by the COVID-19 pandemic, and there is a need for clinical assays that can help optimise resource allocation, support treatment decisions, and accelerate the development and evaluation of new therapies. Methods: We developed a multiplexed proteomics assay for determining disease severity and prognosis in COVID-19. The assay quantifies up to 50 peptides, derived from 30 known and newly introduced COVID-19-related protein markers, in a single measurement using routine-lab compatible analytical flow rate liquid chromatography and multiple reaction monitoring (LC-MRM). We conducted two observational studies in patients with COVID-19 hospitalised at Charité - Universitätsmedizin Berlin, Germany before (from March 1 to 26, 2020, n=30) and after (from April 4 to November 19, 2020, n=164) dexamethasone became standard of care. The study is registered in the German and the WHO International Clinical Trials Registry (DRKS00021688). Findings: The assay produces reproducible (median inter-batch CV of 10.9%) absolute quantification of 47 peptides with high sensitivity (median LLOQ of 143 ng/ml) and accuracy (median 96.8%). In both studies, the assay reproducibly captured hallmarks of COVID-19 infection and severity, as it distinguished healthy individuals, mild, moderate, and severe COVID-19. In the post-dexamethasone cohort, the assay predicted survival with an accuracy of 0.83 (108/130), and death with an accuracy of 0.76 (26/34) in the median 2.5 weeks before the outcome, thereby outperforming compound clinical risk assessments such as SOFA, APACHE II, and ABCS scores. Interpretation: Disease severity and clinical outcomes of patients with COVID-19 can be stratified and predicted by the routine-applicable panel assay that combines known and novel COVID-19 biomarkers. The prognostic value of this assay should be prospectively assessed in larger patient cohorts for future support of clinical decisions, including evaluation of sample flow in routine setting. The possibility to objectively classify COVID-19 severity can be helpful for monitoring of novel therapies, especially in early clinical trials. Funding: This research was funded in part by the European Research Council (ERC) under grant agreement ERC-SyG-2020 951475 (to M.R) and by the Wellcome Trust (IA 200829/Z/16/Z to M.R.). The work was further supported by the Ministry of Education and Research (BMBF) as part of the National Research Node 'Mass Spectrometry in Systems Medicine (MSCoresys)', under grant agreements 031L0220 and 161L0221. J.H. was supported by a Swiss National Science Foundation (SNSF) Postdoc Mobility fellowship (project number 191052). This study was further supported by the BMBF grant NaFoUniMedCOVID-19 - NUM-NAPKON, FKZ: 01KX2021. The study was co-funded by the UK's innovation agency, Innovate UK, under project numbers 75594 and 56328.

Direct evidence for the formation of diastereoisomeric benzylpenicilloyl haptens from benzylpenicillin and benzylpenicillenic acid in patients.

Covalent binding to proteins to form neoantigens is thought to be central to the pathogenesis of penicillin hypersensitivity reactions. We have undertaken detailed mass spectrometric studies to define the mechanism and protein chemistry of hapten formation from benzylpenicillin (BP) and its rearrangement product, benzylpenicillenic acid (PA). Mass spectrometric analysis of human serum albumin exposed to BP and PA in vitro revealed that at low concentrations (drug protein molar ratio 0.001:1) and during short time incubations BP and PA selectively target different residues, Lys199 and Lys525, respectively. Molecular modeling showed that the selectivity was a function of noncovalent interaction before covalent modification. With increased exposure to higher concentrations of BP and PA, multiple epitopes were detected on albumin, demonstrating that the multiplicity of hapten formation is a function of time and concentration. More importantly, we have demonstrated direct evidence that PA is a hapten accounting for the diastereoisomeric BP antigen formation in albumin isolated from the blood of patients receiving penicillin. Furthermore, PA was found to be more potent than BP with respect to stimulation of T cells from patients with penicillin hypersensitivity, illustrating the functional relevance of diastereoisomeric hapten formation.

Estimation of residual glomerular filtration rate in peritoneal dialysis patients using cystatin C: comparison with 51Cr-EDTA clearance.

BACKGROUND: Measuring glomerular filtration rate (GFR) is an important assessment in peritoneal dialysis patients. In clinical practice, it is commonly measured by calculating the mean of the urinary clearance of urea and creatinine (GFR(UrCl)) but this process is time consuming and unreliable. We wished to compare several estimates of GFR including residual GFR estimated from cystatin C (GFR(CysC)) using a published equation (Hoek), GFR(UrCl) and (51)Cr-ethylenediaminetetraacetic acid (EDTA) clearance, in peritoneal dialysis patients. METHODS: GFR(CysC), GFR(UrCl) and (51)Cr-EDTA clearance were measured in 28 patients undergoing peritoneal dialysis in a single dialysis unit. RESULTS: GFR(CysC) was related to GFR(UrCl) (Spearman's rank correlation coefficient r(s) = 0.44; P = 0.0185) and to (51)Cr-EDTA clearance (r(s) = 0.48; P = 0.0099). GFR(CysC) values were significantly (P = 0.0077) lower than (51)Cr-EDTA clearance results (mean bias -19.7%). However, GFR(CysC) did not differ significantly (P > 0.05) from GFR(UrCl). CONCLUSIONS: GFR(CysC) is related to GFR(UrCl) but has a significant negative bias against (51)Cr-EDTA. Given the known limitations of (51)Cr-EDTA in estimating GFR in renal failure, this study provides additional validation suggesting that cystatin C-estimated rGFR (GFR(CysC)) gives a reasonable estimation of GFR without the clinical problems associated with 24 h urine collections.

Accelerated decline of GFR in diabetic nephropathy predicted by interferon release assay to tuberculosis antigens.

BACKGROUND: The QuantiFERON® test (QFT) is a diagnostic tool for active and latent tuberculosis (TB) infections. High rates of positivity to QuantiFERON® have been demonstrated in patients with chronic kidney disease (CKD) and diabetic patients. We performed a pilot study to investigate if QFT positivity in diabetic CKD patients predicted the rate of renal function decline. METHODS: QFT was performed in 38 diabetic patients with CKD 4-5 not on dialysis. The rate of decline in estimated glomerular filtration rate (eGFR) was calculated. RESULTS: 18/38 patients had a positive QFT. Patients with a positive QFT had a steeper decline in eGFR, compared with patients with a negative QFT. Ethnicity (a marker of risk of previous TB exposure), urine protein/creatinine ratio, use of ACE inhibitors/angiotensin II receptor blockers and statins, serum C-reactive protein, vitamin D levels, HbA1c concentration and presenting GFR did not differ significantly. CONCLUSIONS: The finding in this small cohort needs to be replicated in a larger study because our study is susceptible to both type I and type II statistical error. We found that QFT positivity was associated with a more rapid rate of decline in GFR, but this association may be coincidental (with the difference in decline attributed to differences in the blood pressure or proteinuria of the two groups). Moreover, an association does not necessarily mean causality, although it would be interesting to speculate if we are identifying patients with latent TB who have an active interstitial nephritis. Another intriguing possibility is that this assay identifies patients with an immunological phenotype that predisposes to eGFR loss.

Cov-MS: A Community-Based Template Assay for Mass-Spectrometry-Based Protein Detection in SARS-CoV-2 Patients.

Rising population density and global mobility are among the reasons why pathogens such as SARS-CoV-2, the virus that causes COVID-19, spread so rapidly across the globe. The policy response to such pandemics will always have to include accurate monitoring of the spread, as this provides one of the few alternatives to total lockdown. However, COVID-19 diagnosis is currently performed almost exclusively by reverse transcription polymerase chain reaction (RT-PCR). Although this is efficient, automatable, and acceptably cheap, reliance on one type of technology comes with serious caveats, as illustrated by recurring reagent and test shortages. We therefore developed an alternative diagnostic test that detects proteolytically digested SARS-CoV-2 proteins using mass spectrometry (MS). We established the Cov-MS consortium, consisting of 15 academic laboratories and several industrial partners to increase applicability, accessibility, sensitivity, and robustness of this kind of SARS-CoV-2 detection. This, in turn, gave rise to the Cov-MS Digital Incubator that allows other laboratories to join the effort, navigate, and share their optimizations and translate the assay into their clinic. As this test relies on viral proteins instead of RNA, it provides an orthogonal and complementary approach to RT-PCR using other reagents that are relatively inexpensive and widely available, as well as orthogonally skilled personnel and different instruments. Data are available via ProteomeXchange with identifier PXD022550.

Safe nanoengineering and incorporation of transplant populations in a neurosurgical grade biomaterial, DuraGen PlusTM, for protected cell therapy applications.

High transplant cell loss is a major barrier to translation of stem cell therapy for pathologies of the brain and spinal cord. Encapsulated delivery of stem cells in biomaterials for cell therapy is gaining popularity but experimental research has overwhelmingly used laboratory grade materials unsuitable for human clinical use - representing a further barrier to clinical translation. A potential solution is to use neurosurgical grade materials routinely used in clinical protocols which have an established human safety profile. Here, we tested the ability of Duragen Plus™ - a clinical biomaterial used widely in neurosurgical duraplasty procedures, to support the growth and differentiation of neural stem cells- a major transplant population being tested in clinical trials for neurological pathology. Genetic engineering of stem cells yields augmented therapeutic cells, so we further tested the ability of the Duragen Plus™ matrix to support stem cells engineered using magnetofection technology and minicircle DNA vectors- a promising cell engineering approach we previously reported (Journal of Controlled Release, 2016 a &b). The safety of the nano-engineering approach was analysed for the first time using sophisticated data-independent analysis by mass spectrometry-based proteomics. We prove that the Duragen Plus™ matrix is a promising biomaterial for delivery of stem cell transplant populations, with no adverse effects on key regenerative parameters. This advanced cellular construct based on a combinatorial nano-engineering and biomaterial encapsulation approach, could therefore offer key advantages for clinical translation.

Proteomic investigation of urinary markers of carbon-tetrachloride-induced hepatic fibrosis in the Hanover Wistar rat.

Proteomic techniques such as two-dimensional gel electrophoresis (2-DGE) and mass spectrometry have become important tools for the identification of novel biomarkers of toxicity and disease. Ideally, such biomarkers need to be sensitive and organ specific, but, recently, it has become apparent that it would be an additional benefit to be able to measure biomarkers in samples obtained using non-invasive methods. The present study is concerned with the identification of novel urinary markers of hepatic fibrosis. In a carbon-tetrachloride-induced liver fibrosis rat model, analysis of urine by 2-DGE revealed an increase in the concentration of a number of proteins in animals with hepatic fibrosis. Using in-gel trypsin digest and nano-scale liquid chromatography combined with electrospray ionisation tandem mass spectrometry, protein spots were identified as copper/zinc superoxide dismutase, D: -dopachrome tautomerase, beta-2-microglobulin and neutrophil gelatinase associated lipocalin. These proteins are known to have important roles in the inflammatory response.

Prevalence of ceftriaxone-induced red blood cell antibodies in pediatric patients with sickle cell disease and human immunodeficiency virus infection.

Ceftriaxone can be associated with catastrophic immune hemolysis in pediatric patients, particularly those with underlying diseases such as sickle cell disease and human immunodeficiency virus infection. We designed a study to screen for ceftriaxone-induced RBC antibodies in these 2 pediatric populations. The prevalence of anticeftriaxone antibody was 12.5% (8 of 64). Two of these 8 patients with the antibody experienced hemolysis; 1 case was fatal.

Analyzing Glycopeptide Isomers by Combining Differential Mobility Spectrometry with Electron- and Collision-Based Tandem Mass Spectrometry.

Differential mobility spectrometry (DMS) has been employed to separate isomeric species in several studies. Under the right conditions, factors such as separation voltage, temperature, the presence of chemical modifiers, and residence time can combine to provide unique signal channels for isomeric species. In this study, we examined a set of glycopeptide isomers, MUC5AC-3 and MUC5AC-13, which bear an N-acetyl-galactosamine (GalNAc) group on either threonine-3 or threonine-13. When analyzed as a mixture, the resulting MS and MS/MS spectra yield fragmentation patterns that cannot discern these convolved species. However, when DMS is implemented during the analysis of this mixture, two features emerge in the DMS ionogram representing the two glycopeptide isomers. In addition, by locking in DMS parameters at each feature, we could observe several low intensity CID fragments that contain the GalNAc functionality-specific amino acid residues - identifying the DMS separation of each isomer without standards. Besides conventional CID MS/MS, we also implemented electron-capture dissociation (ECD) after DMS separation, and clearly resolved both isomers with this fragmentation method, as well. The electron energy used in these ECD experiments could be tuned to obtain maximum sequence coverage for these glycopeptides; this was critical as these ions were present as doubly protonated species, which are much more difficult to fragment efficiently via electron-transfer dissociation (ETD). Overall, the combination of DMS with electron- or collision-based MS/MS methods provided enhanced separation and sequence coverage for these glycopeptide isomers. Graphical Abstract ᅟ.

The use of non-bronchoscopic brushings to study the paediatric airway.

BACKGROUND: The use of cytology brushes for the purpose of obtaining respiratory cells from adults for clinical and research purposes is well established. However, the safety and utility of non-bronchoscopic brushings to study the paediatric airway has not been assessed. The purpose of this study was to assess the practicality of using non-bronchoscopic brushing to sample epithelial cells from children for investigation of epithelial function in health and disease using a wide range of molecular and cellular techniques. METHODS: Non-bronchoscopic brushing was investigated in a non-selected cohort of healthy, and mildly asthmatic children presenting for surgery unrelated to respiratory conditions, at the major children's hospital in Perth. Safety and side-effects of the procedure were assessed. Cell number, phenotype and viability were measured for all samples. The potential of these cells for use in long-term cell culture, immunohistochemistry, western blotting, quantitative PCR and gene arraying was examined. RESULTS: Non-bronchoscopic brushing was well tolerated in all children. The only significant side effect following the procedure was cough: nursing staff reported cough in 20% of patients; parents reported cough in 40% of patients. Cells sampled were of sufficient quantity and quality to allow cell culture in 93% of samples. Similarly, protein and RNA extracted from the cells was suitable for investigation of both gene and protein expression using micro-array and real-time PCR. CONCLUSION: Non-bronchoscopic brushing in children is safe and easy to perform, and is not associated with any complications. Using this technique, adequate numbers of epithelial cells can be retrieved to allow cell culture, western blotting, real time PCR, and microarray analysis. The purpose of this study is to demonstrate the utility of non-bronchoscopic airway brushing to obtain and study epithelial cells and to encourage others so that we can accelerate our knowledge regarding the role of the epithelium in childhood respiratory disease.

Does aberrant activation of the epithelial-mesenchymal trophic unit play a key role in asthma or is it an unimportant sideshow?

Mechanisms underlying the pathogenesis of asthma remain elusive, although the pathological changes observed in human lungs at autopsy are consistent with those of a well-defined chronic inflammatory process and are related to disease severity. Areas of epithelial metaplasia and damage, and thickening of the sub-epithelial basal lamina, are common findings. Epithelial cell proliferation is accompanied by a concomitant increase in the proliferation of sub-epithelial fibroblasts. Each of these processes can be upregulated by cytokines and growth factors released from undamaged neighboring cells. However, there is mounting evidence to suggest that aberrant repair signals present in chronically inflamed airways may influence epithelial cell proliferation and regeneration. Furthermore, an aberrant repair process occurring at the mucosal surface might trigger a cascade of events deeper within the sub-mucosa, leading to direct effects on the number and behaviour of mesenchymal cells, and the resultant increased deposition of extracellular matrix that contributes to airway wall remodeling. These data have led an increasing number of investigators to ask the question whether the epithelial-mesenchymal trophic unit, central to lung development, becomes "re-activated" in asthma.

Meeting the needs of siblings of children with life-limiting illnesses.

Siblings of children with life-threatening or life-limiting illnesses can face a number of challenges, yet this is a group that is often unacknowledged as needing specific support. It is essential that the needs of siblings are recognised and addressed as part of a family-centred approach. This article discusses the experiences and challenges faced by siblings in such families and what children's nurses can do to help. In particular, it outlines a group intervention offered by a community children's palliative care service.

Mass spectral enhanced detection of Ubls using SWATH acquisition: MEDUSA--simultaneous quantification of SUMO and ubiquitin-derived isopeptides.

Protein modification by ubiquitination and SUMOylation occur throughout the cell and are responsible for numerous cellular functions such as apoptosis, DNA replication and repair, and gene transcription. Current methods for the identification of such modifications using mass spectrometry predominantly rely upon tryptic isopeptide tag generation followed by database searching with in vitro genetic mutation of SUMO routinely required. We have recently described a novel approach to ubiquitin and SUMO modification detection based upon the diagnostic a' and b' ions released from the isopeptide tags upon collision-induced dissociation of reductively methylated Ubl isopeptides (RUbI) using formaldehyde. Here, we significantly extend those studies by combining data-independent acquisition (DIA) with alternative labeling reagents to improve diagnostic ion coverage and enable relative quantification of modified peptides from both MS and MS/MS signals. Model synthetic ubiquitin and SUMO-derived isopeptides were labeled with mTRAQ reagents (Δ0, Δ4, and Δ8) and subjected to LC-MS/MS with SWATH acquisition. Novel diagnostic ions were generated upon CID, which facilitated the selective detection of these modified peptides. Simultaneous MS-based and MS/MS-based relative quantification was demonstrated for both Ub and SUMO-derived isopeptides across three channels in a background of mTRAQ-labeled Escherichia coli digest.