An overview is presented of gas chromatography/mass spectrometry (GC/MS) and liquid chromatography/mass spectrometry (LC/MS), the two major hyphenated techniques employed in metabolic profiling that complement direct 'fingerprinting' methods such as atmospheric pressure ionization (API) quadrupole time-of-flight MS, API Fourier transform MS, and NMR. In GC/MS, the analytes are normally derivatized prior to analysis in order to reduce their polarity and facilitate chromatographic separation. The electron ionization mass spectra obtained are reproducible and suitable for library matching, mass spectral collections being readily available. In LC/MS, derivatization and library matching are at an early stage of development and mini-reviews are provided. Chemical derivatization can dramatically increase the sensitivity and specificity of LC/MS methods for less polar compounds and provides additional structural information. The potential of derivatization for metabolic profiling in LC/MS is demonstrated by the enhanced analysis of plant extracts, including the potential to measure volatile acids such as formic acid, difficult to achieve by GC/MS. The important role of mass spectral library creation and usage in these techniques is discussed and illustrated by examples.

The association of severe COVID-19 with an increased risk of VTE has resulted in specific guidelines for its prevention and management. The VTE risk appears highest in those with critical care admission. The need for post discharge thromboprophylaxis remains controversial and this is reflected in the conflicting recommendations of expert guidelines. Our local protocol provides thromboprophylaxis to COVID-19 patients during admission only. We report post-discharge VTE data from an ongoing quality improvement programme incorporating root cause analysis of hospital-associated VTE (HA-VTE). Following 1,877 hospital discharges associated with COVID-19, there were 9 episodes of HA-VTE diagnosed within 42 days, to give a post-discharge rate of 4.8 per 1000 discharges. Over 2019, following 18,159 discharges associated with a medical admission; there were 56 episodes of HA-VTE within 42 days (3.1 per 1000 discharges). The odds ratio for post-discharge HA-VTE associated with COVID-19 compared to 2019 was 1.6 (95% CI 0.77-3.1). Hospitalisation with COVID-19 does not appear to increase the risk of post-discharge HA-VTE compared to hospitalisation with other acute medical illness. Given the risk-benefit ratio of post discharge thromboprophylaxis remains uncertain, randomised controlled trials to evaluate the role of continuing thromboprophylaxis in patients with COVID-19 following hospital discharge are required.

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Endoneurial laminins (Lms), β1-integrins, and dystroglycan (DG) are important for Schwann cell (SC) ensheathment and myelination of axons. We now show that SC expression of galactosyl-sulfatide, a Lm-binding glycolipid, precedes that of Lms in developing nerves. This glycolipid anchors Lm-1 and -2 to SC surfaces by binding to their LG domains and enables basement membrane (BM) assembly. Revealingly, non–BM-forming fibroblasts become competent for BM assembly when sulfatides are intercalated into their cell surfaces. Assembly is characterized by coalescence of sulfatide, DG, and c-Src into a Lm-associated complex; by DG-dependent recruitment of utrophin and Src activation; and by integrin-dependent focal adhesion kinase phosphorylation. Collectively, our findings suggest that sulfated glycolipids are key Lm anchors that determine which cell surfaces can assemble Lms to initiate BM assembly and DG- and integrin-mediated signaling.

A proteomic-based method has been developed for the detection of chicken meat within mixed meat preparations. The procedure is robust and simple, comprising the extraction of myofibrillar proteins, enrichment of target proteins using OFFGEL isoelectric focusing, in-solution trypsin digestion of myosin light chain 3, and analysis of the generated peptides by liquid chromatography-mass spectrometry/mass spectrometry (LC-MS/MS). Using this approach, it was possible for example to detect 0.5% contaminating chicken in pork meat with high confidence. Quantitative detection of chicken meat was done by using AQUA stable isotope peptides made from the sequence of previously selected species-specific peptide biomarkers. Linearity was observed between the amount of the peptide biomarker and the amount of chicken present in the mixture; further independent replication is required now to validate the method. Apart from its simplicity, this approach has the advantage that it can be used effectively for the detection of both raw and cooked meat. The method is robust, reliable, and sensitive, representing a serious alternative to methods currently in use for these purposes. It is amenable to highly processed foods which can be particularly problematic, as the tertiary protein structure is often affected in processed food precluding immunoassays. In addition, this proteomic analysis will permit the determination of definitive discriminatory sequence, unlike the DNA PCR based methods used presently. The present article also demonstrates the translation of the technology to routine mass spectrometry equipment, making the methodology suitable for public analysts.

Stevens-Johnson syndrome/toxic epidermal necrolysis (SJS/TEN) is a rare, severe mucocutaneous reaction with few large cohorts reported. This multicenter retrospective study included patients with SJS/TEN seen by inpatient consultative dermatologists at 18 academic medical centers in the United States. A total of 377 adult patients with SJS/TEN between January 1, 2000 and June 1, 2015 were entered, including 260 of 377 (69%) from 2010 onward. The most frequent cause of SJS/TEN was medication reaction in 338 of 377 (89.7%), most often to trimethoprim/sulfamethoxazole (89/338; 26.3%). Most patients were managed in an intensive care (100/368; 27.2%) or burn unit (151/368; 41.0%). Most received pharmacologic therapy (266/376; 70.7%) versus supportive care alone (110/376; 29.3%)-typically corticosteroids (113/266; 42.5%), intravenous immunoglobulin (94/266; 35.3%), or both therapies (54/266; 20.3%). Based on day 1 SCORTEN predicted mortality, approximately 78 in-hospital deaths were expected (77.7/368; 21%), but the observed mortality of 54 patients (54/368; 14.7%) was significantly lower (standardized mortality ratio = 0.70; 95% confidence interval = 0.58-0.79). Stratified by therapy received, the standardized mortality ratio was lowest among those receiving both steroids and intravenous immunoglobulin (standardized mortality ratio = 0.52; 95% confidence interval 0.21-0.79). This large cohort provides contemporary information regarding US patients with SJS/TEN. Mortality, although substantial, was significantly lower than predicted. Although the precise role of pharmacotherapy remains unclear, co-administration of corticosteroids and intravenous immunoglobulin, among other therapies, may warrant further study.

To cite this article: Scully M, Brown J, Patel R, McDonald V, Brown CJ, Machin S. Human leukocyte antigen association in idiopathic thrombotic thrombocytopenic purpura: evidence for an immunogenetic link. J Thromb Haemost 2010; 8: 257-62.Summary. Background: Thrombotic thrombocytopenic purpura (TTP) is a rare, acute, life-threatening disorder, associated with a deficiency in ADAMTS 13. The majority of acute, idiopathic, adult TTP cases are associated with anti-ADAM-TS 13 IgG antibodies. However, the factor(s) precipitating an acute TTP episode are not always obvious; indeed, a multifactorial etiology is likely. Objectives and Methods: DNA was used for human leukocyte antigen (HLA) class II typing, using polymerase chain reaction (PCR)-sequencespecific primer and PCR-sequence-specific oligonucleotide probe to methodology to investigate 50 European acquired idiopathic TTP cases. Results: There was an increase in the frequency of HLA-DQB1*0301 (HLA-DQ7) in patients with TTP as compared with controls [58.0% vs. 34.5% (P = 0.048)]. The frequencies of HLA-DRB1*11 and HLA-DRB3* were also significantly increased in TTP patients as compared with controls [44.0% vs. 12.0% (P = 0.0024) and 84.0% vs. 58.0% (P = 0.024)], although it remains uncertain whether susceptibility is influenced by HLA-DQ or HLA-DR molecules or other genes in this haplotype. The frequencies of HLA-DRB1*04 and HLA-DRB4 (HLA-DR53) were significantly decreased in the patient group as compared with controls [10.0% vs. 35.0% and 26.0% vs. 61.5% (P = 0.0096 and P = 0.0024, respectively)], and may have a protective effect against the development of TTP. Conclusion: Analysis identified HLA class II types associated with susceptibility to and a protective effect against the development of acute acquired TTP in European patients. This provides the first description of a genetic factor predicting the risk of developing acquired antibody-mediated TTP.

Summary. Background: Non-adherence to prescribed medication represents a significant factor associated with treatment failure. Pregnant women identified at risk of venous thromboembolism are increasingly being prescribed low-molecularweight heparin (LMWH) during pregnancy and the puerperium. It is important to understand womenÕs views on and adherence to LMWH during pregnancy and the puerperium, so that women gain maximum benefit from the treatment. Objectives: To monitor womenÕs adherence to enoxaparin, when prescribed during pregnancy and the puerperium, and explore their beliefs about the enoxaparin therapy prescribed. Patients/ Methods: A prospective cohort study involving 95 nullparous and multiparous women prescribed enoxaparin for recognized antenatal indications. Adherence to enoxaparin was assessed through self-completion of a diary, additionally verified through laboratory tests. An adapted beliefs about medication questionnaire was administered to women during their pregnancy. Results: Women were highly adherent to enoxaparin: antenatally, mean percentage adherence 97.92%; postnatally, mean percentage adherence 93.37% (paired t-test, P = 0.000). In the cohort of women we followed, their perceived necessity for enoxaparin therapy outweighed any concerns they had regarding enoxaparin antenatally, necessity-concerns differential 2.20. In some women, however, this perceived necessity does decrease postnatally. Conclusions: Our results suggest that most women prescribed enoxaparin are highly adherent to their therapy during the antenatal period and that womenÕs antenatal beliefs about enoxaparin are able to predict a decrease in postnatal adherence. Our results have important clinical implications, particularly when women are initiated on LMWH just during the postnatal period.