1 May 2020

Quantitative proteomics by mass spectrometry is widely used in biomarker research and basic biology research for investigation of phenotype level cellular events. Despite the wide application, the methodology for statistical analysis of differentially expressed proteins has not been unified. Various methods such as t-test, linear model and mixed effect models are used to define changes in proteomics experiments. However, none of these methods consider the specific structure of MS-data. Choices between methods, often originally developed for other types of data, are based on compromises between features such as statistical power, general applicability and user friendliness. Furthermore, whether to include proteins identified with one peptide in statistical analysis of differential protein expression varies between studies. Here we present DEqMS, a robust statistical method developed specifically for differential protein expression analysis in mass spectrometry data. In all datasets investigated there is a clear dependence of variance on the number of PSMs or peptides used for protein quantification. DEqMS takes this feature into account when assessing differential protein expression. This allows for a more accurate data-dependent estimation of protein variance and inclusion of single peptide identifications without increasing false discoveries. The method was tested in several datasets including E.coli proteome spike-in data, using both label-free and TMT-labelled quantification. In comparison to previous statistical methods used in quantitative proteomics, DEqMS showed consistently better accuracy in detecting altered protein levels compared to other statistical methods in both label-free and labelled quantitative proteomics data. DEqMS is available as an R package in Bioconductor.

28 April 2020

This paper aims to assist the region’s local authorities, and their key foreign backers, in understanding how transitional justice can provide alternative avenues for holding local ISIS members to account while contributing to the healing of communities.

A fundamental feature of the eukaryotic cell membrane is the asymmetric arrangement of lipids in its two leaflets. A cell invests significant energy to maintain this asymmetry and uses it to regulate important biological processes, such as apoptosis and vesiculation. The dynamic coupling of the inner or cytoplasmic and outer or exofacial leaflets is a challenging open question in membrane biology. Here, we combined fluorescence lifetime imaging microscopy (FLIM) with imaging total internal reflection fluorescence correlation spectroscopy (ITIR-FCS) to differentiate the dynamics and organization of the two leaflets of live mammalian cells. We characterized the biophysical properties of fluorescent analogs of phosphatidylcholine, sphingomyelin, and phosphatidylserine in the plasma membrane of two mammalian cell lines (CHO-K1 and RBL-2H3). Because of their specific transverse membrane distribution, these probes allowed leaflet-specific investigation of the plasma membrane. We compared the results of the two methods having different temporal and spatial resolution. Fluorescence lifetimes of fluorescent lipid analogs were in ranges characteristic for the liquid ordered phase in the outer leaflet and for the liquid disordered phase in the inner leaflet. The observation of a more fluid inner leaflet was supported by free diffusion in the inner leaflet, with high average diffusion coefficients. The liquid ordered phase in the outer leaflet was accompanied by slower diffusion and diffusion with intermittent transient trapping. Our results show that the combination of FLIM and ITIR-FCS with specific fluorescent lipid analogs is a powerful tool for investigating lateral and transbilayer characteristics of plasma membrane in live cell lines.

The hydrolysis of triglycerides in triglyceride-rich lipoproteins by LPL is critical for the delivery of triglyceride-derived fatty acids to tissues, including heart, skeletal muscle, and adipose tissues. Physiologically active LPL is normally bound to the endothelial cell protein glycosylphosphatidylinositol-anchored high-density lipoprotein binding protein 1 (GPIHBP1), which transports LPL across endothelial cells, anchors LPL to the vascular wall, and stabilizes LPL activity. Disruption of LPL-GPIHBP1 binding significantly alters triglyceride metabolism and lipid partitioning. In this study, we modified the NanoLuc® Binary Technology split-luciferase system to develop a novel assay that monitors the binding of LPL to GPIHBP1 on endothelial cells in real time. We validated the specificity and sensitivity of the assay using endothelial lipase and a mutant version of LPL and found that this assay reliably and specifically detected the interaction between LPL and GPIHBP1. We then interrogated various endogenous and exogenous inhibitors of LPL-mediated lipolysis for their ability to disrupt the binding of LPL to GPIHBP1. We found that angiopoietin-like (ANGPTL)4 and ANGPTL3-ANGPTL8 complexes disrupted the interactions of LPL and GPIHBP1, whereas the exogenous LPL blockers we tested (tyloxapol, poloxamer-407, and tetrahydrolipstatin) did not. We also found that chylomicrons could dissociate LPL from GPIHBP1 and found evidence that this dissociation was mediated in part by the fatty acids produced by lipolysis. These results demonstrate the ability of this assay to monitor LPL-GPIHBP1 binding and to probe how various agents influence this important complex.

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On this opening week of Spring Training, all 30 Major League teams have one thing in common: optimism. Here's an optimism cheat sheet for each of them.

Rays principal owner Stuart Sternberg won't make any big prediction entering the 2019 season, but he still expressed a lot of enthusiasm during Tuesday's media session.

Pathogenic bacteria of the genera Mycobacterium and Corynebacterium cause severe human diseases such as tuberculosis (Mycobacterium tuberculosis) and diphtheria (Corynebacterium diphtheriae). The cells of these species are surrounded by protective cell walls rich in long-chain mycolic acids. These fatty acids are conjugated to the disaccharide trehalose on the cytoplasmic side of the bacterial cell membrane. They are then transported across the membrane to the periplasm where they act as donors for other reactions. We have previously shown that transient acetylation of the glycolipid trehalose monohydroxycorynomycolate (hTMCM) enables its efficient transport to the periplasm in Corynebacterium glutamicum and that acetylation is mediated by the membrane protein TmaT. Here, we show that a putative methyltransferase, encoded at the same genetic locus as TmaT, is also required for optimal hTMCM transport. Deletion of the C. glutamicum gene NCgl2764 (Rv0224c in M. tuberculosis) abolished acetyltrehalose monocorynomycolate (AcTMCM) synthesis, leading to accumulation of hTMCM in the inner membrane and delaying its conversion to trehalose dihydroxycorynomycolate (h2TDCM). Complementation with NCgl2764 normalized turnover of hTMCM to h2TDCM. In contrast, complementation with NCgl2764 derivatives mutated at residues essential for methyltransferase activity failed to rectify the defect, suggesting that NCgl2764/Rv0224c encodes a methyltransferase, designated here as MtrP. Comprehensive analyses of the individual mtrP and tmaT mutants and of a double mutant revealed strikingly similar changes across several lipid classes compared with WT bacteria. These findings indicate that both MtrP and TmaT have nonredundant roles in regulating AcTMCM synthesis, revealing additional complexity in the regulation of trehalose mycolate transport in the Corynebacterineae.

Objective:

GPR40 is a G protein-coupled receptor regulating free fatty acid-induced insulin secretion. We have generated transgenic mice overexpressing the human GPR40 gene (hGPR40-Tg) under control of the mouse insulin II promoter and have used them to examine the role of GPR40 in the regulation of insulin secretion and glucose homeostasis.

NADPH facilitates glucose-stimulated insulin secretion (GSIS) in pancreatic islet (PI) β-cells by an as yet unknown mechanism. We found NADPH oxidase, isoform-4 (NOX4), to be the major producer of cytosolic H₂O₂, essential for GSIS, while the increase in ATP/ADP alone was insufficient. The fast GSIS phase was absent in PIs from NOX4-null, β-cell-specific knockout mice (NOX4βKO) (not NOX2KO), and NOX4-silenced or catalase-overexpressing INS-1E cells. Lentiviral NOX4 overexpression or H₂O₂ rescued GSIS in PIs from NOX4βKO mice. NOX4 silencing suppressed Ca²⁺ oscillations and the patch-clamped ATP-sensitive potassium channel (K_ATP) opened more frequently at high glucose. Mitochondrial H₂O₂, decreasing upon GSIS, provided an alternative redox signaling when 2-oxo-isocaproate or fatty acid oxidation formed superoxide by electron-transport flavoprotein:Q-oxidoreductase. Unlike GSIS, this ceased with mitochondrial antioxidant SkQ1. Both NOX4KO and NOX4βKO strains exhibited impaired glucose tolerance and peripheral insulin resistance. Thus the redox signaling previously suggested to cause β-cell-self-checking – hypothetically induces insulin resistance when absent. In conclusion, ATP plus H₂O₂ elevations constitute an essential switch-on signal of insulin exocytosis for glucose and branched-chain oxoacids as secretagogues (partly for fatty acids). Redox signaling could be impaired by cytosolic antioxidants, hence those targeting mitochondria should be preferred for clinical applications to treat (pre)diabetes at any stage.

Type 2 diabetes mellitus predicts outcome following acute myocardial infarction (AMI). Since underlying mechanics are incompletely understood, we investigated left ventricular (LV) and atrial (LA) pathophysiological changes and their prognostic implications using cardiovascular magnetic resonance (CMR). Consecutive patients (n=1147, n=265 diabetic; n=882 non-diabetic) underwent CMR 3 days after AMI. Analyses included LV ejection fraction (LVEF), global longitudinal, circumferential and radial strains (GLS, GCS and GRS), LA reservoir, conduit and booster pump strains, as well as infarct size, edema and microvascular obstruction. Predefined endpoints were major adverse cardiovascular events (MACE) within 12 months. Diabetic patients had impaired LA reservoir (19.8 vs. 21.2%, p<0.01) and conduit strains (7.6 vs. 9.0%, p<0.01) but not ventricular function or myocardial damage. They were at higher risk of MACE than non-diabetic patients (10.2% vs. 5.8%, p<0.01) with most MACE occurring in patients with LVEF≥35%. Whilst LVEF (p=0.045) and atrial reservoir strain (p=0.024) were independent predictors of MACE in non-diabetic patients, GLS was in diabetic patients (p=0.010). Considering patients with diabetes and LVEF≥35% (n=237), GLS and LA reservoir strain below median were significantly associated with MACE. In conclusion, in patients with diabetes, LA and LV longitudinal strain permit optimized risk assessment early after reperfused AMI with incremental prognostic value over and above LVEF.

Infants born to mothers with obesity have a greater risk for childhood obesity and metabolic diseases; however, the underlying biological mechanisms remain poorly understood. We used a Japanese macaque model to investigate whether maternal obesity combined with a western-style diet (WSD) impairs offspring muscle insulin action. Adult females were fed a control or WSD prior to and during pregnancy through lactation, and offspring subsequently weaned to a control or WSD. Muscle glucose uptake and signaling were measured ex vivo in fetal (n=5-8/group) and juvenile offspring (n=8/group). In vivo signaling was evaluated after an insulin bolus just prior to weaning (n=4-5/group). Maternal WSD reduced insulin-stimulated glucose uptake and impaired insulin signaling at the level of Akt phosphorylation in fetal muscle. In juvenile offspring, insulin-stimulated glucose uptake was similarly reduced by both maternal and post-weaning WSD and corresponded to modest reductions in insulin-stimulated Akt phosphorylation relative to controls. We conclude that maternal WSD leads to a persistent decrease in offspring muscle insulin-stimulated glucose uptake even in the absence of increased offspring adiposity or markers of systemic insulin resistance. Switching offspring to a healthy diet did not reverse the effects of maternal WSD on muscle insulin action suggesting earlier interventions may be warranted.

Prevention of aberrant cutaneous wound repair and appropriate regeneration of an intact and functional integument require the coordinated timing of fibroblast and keratinocyte migration. Here, we identified a mechanism whereby opposing cell-specific motogenic functions of a multifunctional intracellular and extracellular protein, the receptor for hyaluronan-mediated motility (RHAMM), coordinates fibroblast and keratinocyte migration speed and ensures appropriate timing of excisional wound closure. We found that, unlike in WT mice, in Rhamm-null mice, keratinocyte migration initiates prematurely in the excisional wounds, resulting in wounds that have re-surfaced before the formation of normal granulation tissue, leading to a defective epidermal architecture. We also noted aberrant keratinocyte and fibroblast migration in the Rhamm-null mice, indicating that RHAMM suppresses keratinocyte motility but increases fibroblast motility. This cell context–dependent effect resulted from cell-specific regulation of extracellular signal-regulated kinase 1/2 (ERK1/2) activation and expression of a RHAMM target gene encoding matrix metalloprotease 9 (MMP-9). In fibroblasts, RHAMM promoted ERK1/2 activation and MMP-9 expression, whereas in keratinocytes, RHAMM suppressed these activities. In keratinocytes, loss of RHAMM function or expression promoted epidermal growth factor receptor–regulated MMP-9 expression via ERK1/2, which resulted in cleavage of the ectodomain of the RHAMM partner protein CD44 and thereby increased keratinocyte motility. These results identify RHAMM as a key factor that integrates the timing of wound repair by controlling cell migration.

Patrick E. MacDonald
Dec 1, 2002; 51:S434-S442
Section 5: Beta-Cell Stimulus-Secretion Coupling: Hormonal and Pharmacological Modulators

On this opening week of Spring Training, all 30 Major League teams have one thing in common: optimism. Here's an optimism cheat sheet for each of them.

Bruce Bochy, who guided the Giants to three World Series championships in 2010, '12 and '14, announced Monday that he will retire at the end of the 2019 season, capping a celebrated 25-year managerial career in the Majors.

4 September 2019 , Volume 95, Number 5

4 September 2019 , Volume 95, Number 5

A special section in the latest issue explores recent developments in maritime security and ocean governance.

1 April 2012 , Volume 68, Number 2

In the circular economy nothing is wasted. Repair, not replace, is the byword. Felix Preston on a 30-year-old idea whose day is about to dawn

Reality hit home last week when Jamaican bars and their best friends in psychology class, churches, were ordered to radically scale down their activities. Bars, one of the mainstays of our women most socially and economically deprived, were ordered...

On Tuesday, April 14, the International Monetary Fund downgraded Jamaica’s growth prospects to -5.6 per cent. This is a severe contraction warranting substantial Government intervention. However, at times, the Government waits too late to respond...

A few weeks ago while I was hosting a Friday slot of Cliff Hughes Online, a caller engaged me in a brief discussion about a matter that was never at the forefront on my mind. According to him, the inclusion of another major player in the national...

“As the large wooden doors of the chapel opened and I saw my bride for the first time, our minds and hearts communicated in a way only love could evoke.” This sincere sentiment, echoed by the proud groom, only expresses a drop in the ocean of...

A sufficient β-cell mass is crucial for preventing diabetes, and perinatal β-cell proliferation is important in determining the adult β-cell mass. However, it is not yet known how perinatal β-cell proliferation is regulated. Here, we report that serotonin regulates β-cell proliferation through serotonin receptor 2B (HTR2B) in an autocrine/paracrine manner during the perinatal period. In β-cell–specific Tph1 knockout (Tph1 βKO) mice, perinatal β-cell proliferation was reduced along with the loss of serotonin production in β-cells. Adult Tph1 βKO mice exhibited glucose intolerance with decreased β-cell mass. Disruption of Htr2b in β-cells also resulted in decreased perinatal β-cell proliferation and glucose intolerance in adulthood. Growth hormone (GH) was found to induce serotonin production in β-cells through activation of STAT5 during the perinatal period. Thus, our results indicate that GH-GH receptor-STAT5-serotonin-HTR2B signaling plays a critical role in determining the β-cell mass by regulating perinatal β-cell proliferation, and defects in this pathway affect metabolic phenotypes in adults.

On this opening week of Spring Training, all 30 Major League teams have one thing in common: optimism. Here's an optimism cheat sheet for each of them.

On this opening week of Spring Training, all 30 Major League teams have one thing in common: optimism. Here's an optimism cheat sheet for each of them.

On this opening week of Spring Training, all 30 Major League teams have one thing in common: optimism. Here's an optimism cheat sheet for each of them.

Former national footballer Arthur Lattimore has died. Lattimore, who represented Jamaica in the 1970s, lost his battle with throat cancer at his home in Florida on Thursday. Lattimore, who was known as one of Jamaica's most skilful left-sided...

Former national footballer Arthur Lattimore passed away after a long battle with throat cancer. Lattimore, who represented Jamaica’s football team through­out the 1970s, died at his home in Florida, leaving behind five children, grandchildren, and...

Waiting times in theatre can be a source of friction – but is the delay due to mandatory anaesthetic faff around time (MAFAT), or AWOL surgeons? Elizabeth Travis, and orthopaedic house officer in New Zealand and colleagues, have been trying to create and evidence base to argue the toss, and she joins me now to discuss her study, Operating...

Multimorbidity presents a number of different challenges, for the patients living with the conditions, but also for the health professionals caring for them in systems that often are not designed with these more complex needs in mind. Emma Wallace, general practice lecturer, and Susan Smith, a professor of general practice at the Royal College of...

Mark Folman, a GP in Nottinghamshire, is concerned that more and more work, with more and more patients, means less time with those who really need him. BMJ Voices is a collection of readers’ experiences of working in the NHS. For this, The BMJ is seeking short audio submissions from UK listeners. These submissions will be published on...

In the US the licence, or marketing authorisation, for alteplase is limited to 0-3 hours after onset of stroke, but some other countries - including the UK and Australia - have extended the licence to 4.5 hours. In an analysis article on thebmj.com Brian Alper, vice president of evidence based medicine research and development at Dynamed, and...

Cervical screening programmes in many countries stop at around the age of 65 and much of the focus is often on younger women. However, comparatively little attention has been given to older women despite the fact that they account for about a fifth of cases each year and half of deaths. In this podcast Susan Sherman, a senior lecturer in...

"Too many research studies are poorly designed or executed. Too much of the resulting research evidence is withheld or disseminated piecemeal. As the volume of clinical research activity has grown the quality of evidence has often worsened, which has compromised the ability of all health professionals to provide affordable, effective, high value...

It’s been 10 years since electronic cigarettes hit the shelves in a big way - and since there controversy has reigned about their health effects - are they less unhealthy than smoking traditional tobacco cigarettes, and will they increase nicotine dependence? Its to that last point that new research, published on BMJ.com is looking into -...

The number of people estimated to be latently infected with TB - that is infected with TB, which has not yet manifested symptoms - is around 2 billion. That is 1 in 3 people on the planet are infected by the bacteria. The World Health Organization’s website notes that on average 5-10% of those infected with TB will develop active TB. That number...

In 2001, Gottfried Hirnschall joined the WHO to work on the global response to HIV/AIDs, 18 years later he just retired as the director of WHO’s department for HIV and Hepatitis. The intervening period, almost half the time we’ve been aware of the disease the fight against the infection has been characterised by scientific breakthroughs, and...

Direct-to-consumer genetic tests are sold online and in shops as a way to “find out what your DNA says". They insights into ancestry or disease risks; others claim to provide information on personality, athletic ability, and child talent. However, interpretation of genetic data is complex and context dependent, and DTC genetic tests may produce...

Talk Evidence is back, with your monthly take on the world of EBM with Duncan Jarvies and GPs Carl Heneghan (also director for the Centre of Evidence Based Medicine at the University of Oxford) and Helen Macdonald (also The BMJ's UK research Editor). This month Helen talks about the messy business of colon cancer screening - which modality is...

We know that the number of people living with multiple health conditions is rising year on year, and yet training, guidelines, organisations and physical spaces in healthcare still largely focus on single diseases or organ systems. The means that patients in the NHS are often treated as if their conditions exist in isolation, and that their care...

T Inoguchi
Nov 1, 2000; 49:1939-1945
Articles

Eve Van Cauter
Mar 1, 1992; 41:368-377
Original Article

G Xu
Dec 1, 1999; 48:2270-2276
Articles

HE Hohmeier
Mar 1, 2000; 49:424-430
Articles

On this opening week of Spring Training, all 30 Major League teams have one thing in common: optimism. Here's an optimism cheat sheet for each of them.

THE EDITOR, Madam: Humour exists in the rough times. Creative individuals have made social distancing with serious body language codes attractive and endearing. The king of the jungle knows just how to cheer you up, even across a wide football...