D-dimer assays--a help or hindrance in suspected pulmonary thromboembolism assessment?

BACKGROUND: Suspected pulmonary thromboembolism (PTE) is a common presentation to acute medical units and can cause diagnostic difficulty. National guidelines on PTE management highlight the need for clinical probability assessment and D-dimer assays to ensure appropriate use of diagnostic imaging. D-dimers are used widely in UK hospitals, yet concern exists regarding their misuse. AIMS: In this study we aimed to assess the impact of the introduction of D-dimer assays, combined with clinical probability assessment, for evaluation of suspected PTE in our unit. MATERIALS AND METHODS: This was a prospective audit of all patients presenting with suspected PTE over two 12-week periods, exactly 1 year apart. D-dimers were introduced into our unit between these two periods. We recorded the clinical probability score, potential causes of false-positive D-dimer assay, diagnostic imaging result, patient outcome, admission rates, and length of inpatient stay. STATISTICAL ANALYSIS: Categorical variables were compared using a 2 x 2 chi-square test or Fisher's exact test. Groups were compared utilizing the two-sample t-test or Mann-Whitney U test. RESULTS: A total of 190 patients were included in the study; 65% were female. PTE was confirmed in 8.4%. Patients in both audit periods were comparable with regard to suitability for D-dimer measurement. Following D-dimer introduction, 40 out of 110 patients in period 2 could be discharged directly from the emergency department. Of those admitted to hospital, the median length of stay was significantly reduced in period 2 (3 days in period 1 vs 1 day in period 2; P=0.0007). Use of diagnostic imaging was significantly reduced following the introduction of D-dimers (90% in period 1 vs 40% in period 2; P<0.0001). The positive diagnostic yield for PTE on CT pulmonary angiogram (CTPA) increased significantly from 10% in period 1 to 23% in period 2 (P=0.039). CONCLUSION: D-dimers must be used judiciously in the assessment of suspected PTE. Appropriate use of D-dimers can provide many benefits, including reductions in diagnostic imaging (and thus radiation exposure), admission rates, and length of inpatient stay.

Staging of non-small cell lung cancer (NSCLC): a review.

Lung cancer remains the most common cause of cancer-related mortality in Scotland, accounting for 28.9% of all cancer deaths in 2007. (1) Current guidelines recommend assessment of patient fitness and operability by a multi-disciplinary team when selecting management options. (2-6) Two of the most important prognostic markers are the stage of disease and ECOG performance status. The most commonly used cancer staging system is the tumour, node, metastasis (TNM) staging system, which is maintained by the American Joint Committee on Cancer (AJCC) and the International Union Against Cancer (UICC). In 1998, the International Association for the Study of Lung Cancer (IASLC) established The Lung Cancer Staging Project, collecting data on over 100,000 patients diagnosed with lung cancer between 1990-2000 worldwide, in order to revise the 6th edition TNM staging system for non-small cell lung cancer (NSCLC).(7) The 7th edition was published in late 2009. This review of staging in NSCLC, includes a summary of the different staging techniques currently available and the 7th edition TNM staging system for NSCLC.(8).

Structure, function and evolution of glutathione transferases: implications for classification of non-mammalian members of an ancient enzyme superfamily.

The glutathione transferases (GSTs; also known as glutathione S-transferases) are major phase II detoxification enzymes found mainly in the cytosol. In addition to their role in catalysing the conjugation of electrophilic substrates to glutathione (GSH), these enzymes also carry out a range of other functions. They have peroxidase and isomerase activities, they can inhibit the Jun N-terminal kinase (thus protecting cells against H(2)O(2)-induced cell death), and they are able to bind non-catalytically a wide range of endogenous and exogenous ligands. Cytosolic GSTs of mammals have been particularly well characterized, and were originally classified into Alpha, Mu, Pi and Theta classes on the basis of a combination of criteria such as substrate/inhibitor specificity, primary and tertiary structure similarities and immunological identity. Non-mammalian GSTs have been much less well characterized, but have provided a disproportionately large number of three-dimensional structures, thus extending our structure-function knowledge of the superfamily as a whole. Moreover, several novel classes identified in non-mammalian species have been subsequently identified in mammals, sometimes carrying out functions not previously associated with GSTs. These studies have revealed that the GSTs comprise a widespread and highly versatile superfamily which show similarities to non-GST stress-related proteins. Independent classification systems have arisen for groups of organisms such as plants and insects. This review surveys the classification of GSTs in non-mammalian sources, such as bacteria, fungi, plants, insects and helminths, and attempts to relate them to the more mainstream classification system for mammalian enzymes. The implications of this classification with regard to the evolution of GSTs are discussed.

Variable expression of glutathione S-transferase isoenzymes in the fungus, Mucor circinelloides.

Mucor circinelloides (previously M. javanicus) variably expresses two isoenzymes of glutathione S-transferases. Glutathione S-transferases 1 and 2 were purified by affinity chromatography and found to be dimers with subunit M(r) values of 25.5 and 28. While glutathione S-transferase 1 immunoblotted with rat glutathione S-transferase T 5-5, N-terminal sequencing indicated that this enzyme was distinct from recently characterised bacterial and fungal glutathione S-transferases and did not readily fit into any one class. It showed some similarity to several classes including insect class II and plant type III. M. circinelloides glutathione S-transferase 2 did not immunoblot and yielded no N-terminal sequence.

Glutathione S-transferases from the white-rot fungus, Phanerochaete chrysosporium.

A glutathione S-transferase (GST) was purified to homogeneity from the white-rot fungus, Phanerochaete chrysosporium, by affinity chromatography on glutathione-agarose followed by Mono-Q ion-exchange FPLC. This protein immunoblotted with antisera to rat Theta class GST 5-5 and also showed N-terminal sequence similarity to the Theta class, including the presence of a conserved serine residue that has been specifically implicated in catalysis in this class [Wilce, Board, Feil and Parker (1995) EMBO J. 14, 2133-2143] and other residues conserved in plant sequences. Catalytic activity was found to be highly labile in the purified protein, although preliminary evidence for activity (approx. 120 m-units/mg) with 1,2-epoxy-3-(p-nitrophenoxy)propane was obtained in some preparations. The enzyme seems to be a dimer with a subunit molecular mass of 25 kDa by SDS/PAGE. The native molecular masses estimated by non-denaturing electrophoresis and by Superose-12 gel filtration were 58 and 45 kDa respectively. A second protein purified in this study also gave low level of activity with 1,2-epoxy-3-(p-nitrophenoxy)propane and had a subunit molecular mass of 28 kDa (native size 62-63 kDa), but did not immunoblot with any GST class and seemed to be N-terminally blocked.

Effects of hormones and cysteine protease modulators on infection of HepG2 cells by Plasmodium berghei sporozoites in vitro determined by ELISA immunoassay.

An enzyme-linked immunosorbent assay (ELISA) detecting a Plasmodium berghei liver-stage-specific protein Pbl-1 is described. The quantitative detection limits ranged from 0.01 to 0.05 microgram of parasite protein. Qualitatively the assay detected as little as 0.001 microgram Pbl-1 per well. Using the ELISA dexamethasone and insulin together was shown to promote higher parasite infections in HepG2 cells compared to unsupplemented medium. Anti-cowpea-protease cysteine inhibitor significantly increased hepatocyte invasion as compared to controls, whereas a significant decrease was recorded in the presence of the protease inhibitor E64. Partial involvement of cysteine proteases in HepG2 invasion by P. berghei sporozoites is therefore suggested.

A liver-stage specific antigen of P. berghei identified by a monoclonal antibody.

Stage-specific immunity (to the sporozoite, the asexual blood-stages and the sexual stages of malaria) has been well documented and antigens from each stage are being tested for their potential as vaccine candidates. Recently it has become clear that the liver stage can also be the target of protective immune responses; however, only the circumsporozoite protein has been identified as a protective liver antigen. It is critical for vaccine evaluation and development to identify other liver antigens and assess their potential role in immunity. In this paper we describe a monoclonal antibody, which recognizes a liver-specific antigen of Plasmodium berghei (referred to as Pbl1). Passive immunization studies using this antibody suggest that it may influence the course of sporozoite-induced infections.