Inhibition of Arabidopsis growth by the allelopathic compound azetidine-2-carboxylate is due to the low amino acid specificity of cytosolic prolyl-tRNA synthetase

The toxicity of azetidine-2-carboxylic acid (A2C), a structural analogue of L-proline, results from its incorporation into proteins due to misrecognition by prolyl-tRNA synthetase (ProRS). The growth of Arabidopsis thaliana seedling roots is more sensitive to inhibition by A2C than is cotyledon growth. Arabidopsis contains two ProRS isozymes. AtProRS-Org (At5g52520) is localized in chloroplasts/mitochondria, and AtProRS-Cyt (At3g62120) is cytosolic. AtProRS-Cyt mRNA is more highly expressed in roots than in cotyledons. Arabidopsis ProRS isoforms were expressed as His-tagged recombinant proteins in Escherichia coli. Both enzymes were functionally active in ATP-PPi exchange and aminoacylation assays, and showed similar K_m for L-proline. A major difference was observed in the substrate specificity of the two enzymes. AtProRS-Cyt showed nearly identical substrate specificity for L-proline and A2C, but for AtProRS-Org the specificity constant was 77.6 times higher for L-proline than A2C, suggesting that A2C-sensitivity may result from lower amino acid specificity of AtProRS-Cyt. Molecular modelling and simulation results indicate that this specificity difference between the AtProRS isoforms may result from altered modes of substrate binding. Similar kinetic results were obtained with the ProRSs from Zea mays, suggesting that the difference in substrate specificity is a conserved feature of ProRS isoforms from plants that do not accumulate A2C and are sensitive to A2C toxicity. The discovery of the mode of action of A2C toxicity could lead to development of biorational weed management strategies.

Circulating T-helper 17 cells and associated cytokines in psoriasis

BACKGROUND

Recently, a new population of IL-17-producing CD4 T helper (Th) cells, named Th17, was identified and shown to be involved in various inflammatory and autoimmune diseases, including psoriasis.

AIM

To determine the frequency of Th17 cells and related cytokines in peripheral blood of patients with psoriasis, and to analyse their association with disease severity.

METHODS

This was a prospective study comprising 34 patients with psoriasis and 24 healthy controls. Clinicoepidemiological details of patients were recorded, and severity of psoriasis was assessed by means of the Psoriasis Area and Severity Index. Circulating Th1 and Th17 cells in untreated patients with psoriasis and healthy controls were quantified by flow cytometry. In sera collected from patients with psoriasis and healthy controls, concentrations of IL-17A and IL-23 were examined by ELISA.

RESULTS

Increased frequencies of CD4+ IL-17A+ T cells were seen in peripheral blood of patients with psoriasis vulgaris (P < 0.001). Although serum IL-17A and IL-23 concentrations were higher in patients with psoriasis than in controls, the results did not reach statistical significance. We could not find any correlation between the studied T cells or related cytokines and the disease severity.

CONCLUSION

Increased serum levels of circulating Th17 cells and related cytokines may contribute to the cutaneous pathology of psoriasis, as well as the inflammatory process that is a hallmark of psoriasis.

OC-11 - Anticoagulation therapy in selected cancer patients at risk of recurrence of venous thromboembolism

INTRODUCTION

Venous thromboembolism (VTE) in cancer patients is an increasingly frequent clinical problem. The overall impact of VTE on cancer patients can be considerable. Targeted patient selection by identifying patients with clinically significant recurrent VTE may have wider health economic benefits whilst reducing patient risk through over-treatment. In the UK, dalteparin is one licensed anticoagulant for the extended treatment and prevention of recurrence of VTE in cancer patients. Rivaroxaban is a highly selective direct Factor Xa inhibitor with oral bioavailability.

AIM

To assess VTE recurrence in selected cancer patients at risk of recurrence of VTE treated with rivaroxaban or dalteparin. The secondary objectives include safety, acceptability, biomarker identification and health economics.

MATERIALS AND METHODS

Select-d is a prospective, randomised, open label, multicentre pilot trial comparing dalteparin (200 IU/kg daily subcutaneously for 1 month and 150 IU/kg months 2-6); and rivaroxaban (15mg orally twice daily for 3 weeks and 20mg once daily for 6 months in total) for cancer patients with VTE - symptomatic and incidental pulmonary embolism (P)E or symptomatic lower limb proximal deep vein thrombosis (DVT) - with a second placebo-controlled randomisation (rivaroxaban vs placebo) comparing the duration of therapy (6 vs 12 months) in all patients with PE and those with a DVT who are residual vein thrombosis (RVT) positive. 70% of DVT patients are estimated to be RVT positive after initial treatment. 530 patients are being recruited toprovide reliable estimates of the primary outcome (VTE recurrence rates) to within the 95% confidence interval of 8% assuming VTE rates are 10% at six months.

RESULTS

As of 1st December 2015, 264 patients have been recruited from 61 open sites across the UK. Preliminary data indicate that the majority of patients presented with solid tumours (98%), ranging from early or locally advanced (41%) to metastatic disease (57%), and primarily comprising colorectal, lung, and breast malignancies. Only a small number of select-d patients presented with haematological malignancies (2%), which included; leukaemia, myeloma and lymphoma. Over half of the select-d patients had an incidental PE (54%); the remainder had symptomatic PE or DVT (46%). The median number of hours on anticoagulation prior to starting select-d randomised treatment was 48 hours.

CONCLUSIONS

select-d is the first randomised trial for treatment of VTE, investigating the direct oral anticoagulants vs a low molecular weight heparin in patients with cancer. The results will support optimal treatment for this key patient group and are eagerly awaited.

Identification of P450 Oxidoreductase as a Major Determinant of Sensitivity to Hypoxia-Activated Prodrugs

Hypoxia is a prevalent feature of many tumors contributing to disease progression and treatment resistance, and therefore constitutes an attractive therapeutic target. Several hypoxia-activated prodrugs (HAP) have been developed, including the phase III candidate TH-302 (evofosfamide) and the preclinical agent SN30000, which is an optimized analogue of the well-studied HAP tirapazamine. Experience with this therapeutic class highlights an urgent need to identify biomarkers of HAP sensitivity, including enzymes responsible for prodrug activation during hypoxia. Using genome-scale shRNA screens and a high-representation library enriched for oxidoreductases, we identified the flavoprotein P450 (cytochrome) oxidoreductase (POR) as the predominant determinant of sensitivity to SN30000 in three different genetic backgrounds. No other genes consistently modified SN30000 sensitivity, even within a POR-negative background. Knockdown or genetic knockout of POR reduced SN30000 reductive metabolism and clonogenic cell death and similarly reduced sensitivity to TH-302 under hypoxia. A retrospective evaluation of head and neck squamous cell carcinomas showed heterogeneous POR expression and suggested a possible relationship between human papillomavirus status and HAP sensitivity. Taken together, our study identifies POR as a potential predictive biomarker of HAP sensitivity that should be explored during the clinical development of SN30000, TH-302, and other hypoxia-directed agents.

A retrospective evaluation of the NHS Health Check Programme in a multi-ethnic population

BACKGROUND

The NHS Health Check Programme was introduced in 2009 to improve primary prevention of coronary heart disease, stroke, diabetes and chronic kidney disease; however, there has been debate regarding the impact. We present a retrospective evaluation of Leicester City Clinical Commissioning Group.

METHODS

Data are reported on diagnosis of type 2 diabetes, hypertension, chronic kidney disease, high risk of type 2 diabetes and high risk of cardiovascular disease. Data on management following the Health Check are also reported.

RESULTS

Over a 5-year period, 53 799 health checks were performed, 16 388 (30%) people were diagnosed with at least one condition when diagnosis of being at high risk of cardiovascular disease was defined as ≥20%. This figure increased to 43% when diagnosis of high cardiovascular risk ≥10% was included. Of the 3063 (5.7%) individuals diagnosed with type 2 diabetes, 54% were prescribed metformin and 26% were referred for structured education. Of the 5797 (10.8%) individuals diagnosed at high risk of cardiovascular disease (≥20%), 64% were prescribed statins.

CONCLUSIONS

A high proportion of new cases of people at risk of cardiovascular disease were identified by the NHS Health Check Programme. Data suggest that this has translated into appropriate preventative measures.

Stokes phenomena in discrete Painlevé I

In this study, we consider the asymptotic behaviour of the first discrete Painlevé equation in the limit as the independent variable becomes large. Using an asymptotic series expansion, we identify two types of solutions which are pole-free within some sector of the complex plane containing the positive real axis. Using exponential asymptotic techniques, we determine Stokes phenomena effects present within these solutions, and hence the regions in which the asymptotic series expression is valid. From a careful analysis of the switching behaviour across Stokes lines, we find that the first type of solution is uniquely defined, while the second type contains two free parameters, and that the region of validity may be extended for appropriate choice of these parameters.

Development and characterization of Haemophilus influenzae type b conjugate vaccine prepared using different polysaccharide chain lengths

Capsular polysaccharide conjugates of Haemophilus influenzae type b (Hib) are important components of several mono- or multi-valent childhood vaccines. However, their access to the most needy people is limited due to their high cost. As a step towards developing a cost effective and more immunogenic Hib conjugate vaccine, we present a method for the preparation of Hib capsular polysaccharide (PRP)-tetanus toxoid (TT) conjugates using optimized PRP chain length and conjugation conditions. Reactive aldehyde groups were introduced into the polysaccharides by controlled periodate oxidation of the native polysaccharide, which were subsequently covalently linked to hydrazide derivatized tetanus toxoid by means of reductive amination. Native polysaccharides were reduced to average 100 or 50kDa polysaccharide and 10kDa oligosaccharides in a controlled manner. Various conjugates were prepared using Hib polysaccharide and oligosaccharide yielding conjugates with polysaccharide to protein ratios in the range of 0.25-0.5 (w/w) and free saccharide levels of less than 10%. Immunization of Sprague Dawley rats with the conjugates elicited specific antibodies to PRP. The low molecular weight PRP-TT conjugates were found to be more immunogenic as compared to their high molecular weight counterparts and the PRP-TT reference vaccine.

Coagulation-driven platelet activation reduces cholestatic liver injury and fibrosis in mice

BACKGROUND

The coagulation cascade has been shown to participate in chronic liver injury and fibrosis, but the contribution of various thrombin targets, such as protease activated receptors (PARs) and fibrin(ogen), has not been fully described. Emerging evidence suggests that in some experimental settings of chronic liver injury, platelets can promote liver repair and inhibit liver fibrosis. However, the precise mechanisms linking coagulation and platelet function to hepatic tissue changes following injury remain poorly defined.

OBJECTIVES

To determine the role of PAR-4, a key thrombin receptor on mouse platelets, and fibrin(ogen) engagement of the platelet αII b β3 integrin (αIIb β3 ) in a model of cholestatic liver injury and fibrosis.

METHODS

Biliary and hepatic injury was characterized following 4 week administration of the bile duct toxicant α-naphthylisothiocyanate (ANIT) (0.025%) in PAR-4-deficient mice, mice expressing a mutant form of fibrin(ogen) incapable of binding integrin αII b β3 (Fibγ(Δ5) ), and wild-type mice.

RESULTS

Elevated plasma thrombin-antithrombin and serotonin levels, hepatic fibrin deposition, and platelet accumulation in liver accompanied hepatocellular injury and fibrosis in ANIT-treated wild-type mice. PAR-4 deficiency reduced plasma serotonin levels, increased serum bile acid concentration, and exacerbated ANIT-induced hepatocellular injury and peribiliary fibrosis. Compared with PAR-4-deficient mice, ANIT-treated Fibγ(Δ5) mice displayed more widespread hepatocellular necrosis accompanied by marked inflammation, robust fibroblast activation, and extensive liver fibrosis.

CONCLUSIONS

Collectively, the results indicate that PAR-4 and fibrin-αII b β3 integrin engagement, pathways coupling coagulation to platelet activation, each exert hepatoprotective effects during chronic cholestasis.

Conversion of S-phenylsulfonylcysteine residues to mixed disulfides at pH 4.0: utility in protein thiol blocking and in protein-S-nitrosothiol detection

A three step protocol for protein S-nitrosothiol conversion to fluorescent mixed disulfides with purified proteins, referred to as the thiosulfonate switch, is explored which involves: (1) thiol blocking at pH 4.0 using S-phenylsulfonylcysteine (SPSC); (2) trapping of protein S-nitrosothiols as their S-phenylsulfonylcysteines employing sodium benzenesulfinate; and (3) tagging the protein thiosulfonate with a fluorescent rhodamine based probe bearing a reactive thiol (Rhod-SH), which forms a mixed disulfide between the probe and the formerly S-nitrosated cysteine residue. S-Nitrosated bovine serum albumin and the S-nitrosated C-terminally truncated form of AdhR-SH (alcohol dehydrogenase regulator) designated as AdhR*-SNO were selectively labelled by the thiosulfonate switch both individually and in protein mixtures containing free thiols. This protocol features the facile reaction of thiols with S-phenylsulfonylcysteines forming mixed disulfides at mild acidic pH (pH = 4.0) in both the initial blocking step as well as in the conversion of protein-S-sulfonylcysteines to form stable fluorescent disulfides. Labelling was monitored by TOF-MS and gel electrophoresis. Proteolysis and peptide analysis of the resulting digest identified the cysteine residues containing mixed disulfides bearing the fluorescent probe, Rhod-SH.

Reconstruction of complex soft-tissue defects around the knee joint with distally based split vastus lateralis musculocutaneous flap: a new technique

AIMS

The aim of this study was to report our experience of using distally based spilt vastus lateralis musculocutaneous flaps for soft-tissue defects around the knee joint - a new technique.

MATERIAL AND METHODS

Cadaver dissection studies were conducted in three cadavers to demonstrate perforators entering the lower third of the vastus lateralis muscle arising from the superior lateral genicular artery. Its application in eight clinical cases for the reconstruction of soft-tissue defects around the knee joint is reported.

RESULTS

Seven out of eight flaps survived well without any flap loss. One flap with a skin island measuring 12 × 20 cm suffered a loss of 2 cm distally. This was later treated with skin grafting. Six out of eight donor sites were closed primarily. Six patients achieved full functional range of motion by 3 months. One patient had a 10° limitation of knee extension. One patient had foot drop due to primary injury and walks with a limping gait.

CONCLUSIONS

This flap is a new reconstructive option for knee defects. It can reach distally up to the tibial tuberosity and does not require an intraoperative change of position. The donor site can be closed primarily and is hidden inside the clothing. The function of the knee is not affected as the majority of the muscle is kept in continuity.

Aberrant gene expression in the Arabidopsis SULTR1;2 mutants suggests a possible regulatory role for this sulfate transporter in response to sulfur nutrient status

Sulfur is required for the biosynthesis of cysteine, methionine and numerous other metabolites, and thus is critical for cellular metabolism and various growth and developmental processes. Plants are able to sense their physiological state with respect to sulfur availability, but the sensor remains to be identified. Here we report the isolation and characterization of two novel allelic mutants of Arabidopsis thaliana, sel1-15 and sel1-16, which show increased expression of a sulfur deficiency-activated gene β-glucosidase 28 (BGLU28). The mutants, which represent two different missense alleles of SULTR1;2, which encodes a high-affinity sulfate transporter, are defective in sulfate transport and as a result have a lower cellular sulfate level. However, when treated with a very high dose of sulfate, sel1-15 and sel1-16 accumulated similar amounts of internal sulfate and its metabolite glutathione (GSH) to wild-type, but showed higher expression of BGLU28 and other sulfur deficiency-activated genes than wild-type. Reduced sensitivity to inhibition of gene expression was also observed in the sel1 mutants when fed with the sulfate metabolites Cys and GSH. In addition, a SULTR1;2 knockout allele also exhibits reduced inhibition in response to sulfate, Cys and GSH, consistent with the phenotype of sel1-15 and sel1-16. Taken together, the genetic evidence suggests that, in addition to its known function as a high-affinity sulfate transporter, SULTR1;2 may have a regulatory role in response to sulfur nutrient status. The possibility that SULTR1;2 may function as a sensor of sulfur status or a component of a sulfur sensory mechanism is discussed.

Marked retroperitoneal lymphadenopathy in hairy cell leukemia: a case report

Hairy cell leukemia (HCL) is uncommonly associated with lymphadenopathy, while retroperitoneal lymphadenopathy is extremely uncommon. We report on a patient with a 12-year history of HCL who developed painless jaundice and ascites, accompanied by positional discomfort with persistent nausea. Computed tomography examination revealed 2 large retroperitoneal masses, which at autopsy consisted of HCL with focally intermixed pancreatic and peripancreatic tissue. Lymphadenopathy was not identified above the diaphragm or below the aortic bifurcation. No vasculitis or an unusual HCL histology was identified. As previous reports, our findings suggest that HCL with massive lymphadenopathy has a specific site predilection, but it is not necessarily accompanied by vasculitis or an unusual histology.

A computer-aided algorithm to quantitatively predict lymph node status on MRI in rectal cancer

OBJECTIVE

The aim of this study was to demonstrate the principle of supporting radiologists by using a computer algorithm to quantitatively analyse MRI morphological features used by radiologists to predict the presence or absence of metastatic disease in local lymph nodes in rectal cancer.

METHODS

A computer algorithm was developed to extract and quantify the following morphological features from MR images: chemical shift artefact; relative mean signal intensity; signal heterogeneity; and nodal size (volume or maximum diameter). Computed predictions on nodal involvement were generated using quantified features in isolation or in combinations. Accuracies of the predictions were assessed against a set of 43 lymph nodes, determined by radiologists as benign (20 nodes) or malignant (23 nodes).

RESULTS

Predictions using combinations of quantified features were more accurate than predictions using individual features (0.67-0.86 vs 0.58-0.77, respectively). The algorithm was more accurate when three-dimensional images were used (0.58-0.86) than when only middle image slices (two-dimensional) were used (0.47-0.72). Maximum node diameter was more accurate than node volume in representing the nodal size feature; combinations including maximum node diameter gave accuracies up to 0.91.

CONCLUSION

We have developed a computer algorithm that can support radiologists by quantitatively analysing morphological features of lymph nodes on MRI in the context of rectal cancer nodal staging. We have shown that this algorithm can combine these quantitative indices to generate computed predictions of nodal status which closely match radiological assessment. This study provides support for the feasibility of computer-assisted reading in nodal staging, but requires further refinement and validation with larger data sets.

Assessment of characteristics of patient with delirium tremens

Delirium tremens is the severe form of alcohol withdrawal. It carries a certain degree of mortality and there has been and advancement in the understanding of pathophysiology and risk factors for the development of the condition. This prospective study is carried out to study the characteristic of the patient of delirium tremens in our setting using ICD-10 diagnostic criteria. Thirty seven cases of delirium tremens with majority of males and of all hill origin people were identified. Patients with delirium tremens has been using alcohol for average of 24.8 years with an average intake of around 2.2 litres per day. Most of the patient has seizure and similar episodes in past and using alcohol from morning time.