Comparison of greenhouse gas emissions from sheep measured using both respiration and portable accumulation chambers

Methane (CH4) is a potent gas produced by ruminants, and new measurement techniques are required to generate large datasets suitable for genetic analysis. One such technique are portable accumulation chambers (PAC), a short-term sampling method. The objectives of the current study were to explore the relationship between CH4 and carbon dioxide (CO2) output measured using both PAC and respiration chambers (RC) in growing lambs, and separately investigate the relationship among CH4, CO2 and measured ad libitum DM intake (DMI). Methane, CO2 and DMI were measured on 30 Suffolk and 30 Texel ewe lambs (age 253 ± 12 days) using the RC and PAC sequentially. The experiment was conducted over a 14-day period, with DMI measured from days 1 to 14; measurements in RC were conducted from days 10 to 12, while measurements in PAC were taken twice, the day immediately prior to the lambs entering the RC (day 9; PAC Pre-RC) and on the day lambs exited the RC (day 13; PAC Post-RC). Greater CH4 and CO2 output was measured in the RC than in the PAC (P < 0.01); similarly mean CH4 yield was greater when measured in the RC (15.39 ± 0.452 g CH4/kg DMI) compared to PAC (8.01 ± 0.767 g CH4/kg DMI). A moderate correlation of 0.37 was found between CH4 output measured in PAC Pre-RC and the RC, the corresponding regression coefficient of CH4 output measured in the RC regressed on CH4 output measured in PAC Pre-RC was close to unity (0.74; SE 0.224). The variance of CH4 and CO2 output within the measurement technique did not differ from each other (P > 0.05). Moderate to strong correlations were found between CH4 and CO2 per kg of live weight and CH4 and CO2 yield. Results from this study highlight the suitability of PAC as a ranking tool to rank animals based on their gaseous output when compared to the RC. However, repeated measurements separated by several days may be beneficial if precise rankings are required. Given the close to unity regression coefficient of CH4 output measured in the RC regressed on CH4 output measured in PAC Pre-RC suggests that PAC could also be potentially used to estimate absolute CH4 output; however, further research is required to substantiate this claim. When DMI is unknown, CH4 and CO2 per kg of live weight are a suitable alternative to the measurement of CH4 and CO2 yield.

The modulation of platelet function by growth hormone in growth hormone deficient Hypopituitary patients

BACKGROUND

Growth hormone deficiency (GHD) has been implicated in increased cardiovascular and cerebrovascular disease risk seen in hypopituitarism, however the mechanism remains speculative. We hypothesise that platelet abnormalities may play a contributory role. Herein we examined platelet behaviour in GHD hypopituitary patients, pre- and post-growth hormone (GH) replacement.

METHODS

This study utilizes a physiological flow-based assay to quantify platelet function in whole blood from patient cohorts under arterial shear. Thirteen GH Naïve hypopituitary adults with GHD and thirteen healthy matched controls were studied. Patients were assessed before and after GH treatment. All other pituitary replacements were optimised before the study. In addition to a full endocrine profile, whole blood was labelled and perfused over immobilised von Willibrand factor (vWF). Seven parameters of dynamic platelet-vWF interactions were recorded using digital image microscopy and analysed by customised platelet tracking software.

RESULTS

We found a significantly altered profile of platelet-vWF interactions in GHD individuals compared to healthy controls. Specifically, we observed a marked increase in platelets shown to form associations such as tethering, rolling and adherence to immobilized vWF, which were reduced post GH treatment. Speed and distance platelets travelled across vWF was similar between controls and pre-therapy GHD patients, however, this was considerably increased post treatment. This may indicate reduced platelet signaling resulting in less stable adhesion of platelets post GH treatment.

CONCLUSIONS

Taken together observed differences in platelet behaviour may contribute to an increased risk of thrombosis in GHD which can in part be reversed by GH therapy.

Nanotopography of Polystyrene/Poly(methyl methacrylate) for the Promotion of Patient Specific Von Willebrand Factor Entrapment and Platelet Adhesion in a Whole Blood Microfluidic Assay

Platelet function testing is essential for the diagnosis of patients with bleeding disorders. Specifically, there is a need for a whole blood assay that is capable of analysing platelet behaviour in contact with a patient-specific autologous von Willebrand factor (vWF), under physiologically relevant conditions. The creation of surface topography capable of entrapping and uncoiling vWF for the support of subsequent platelet adhesion within the same blood sample offers a potential basis for such an assay. In this study, spin coating of polystyrene/poly (methyl methacrylate) (PS/PMMA) demixed solutions onto glass substrates in air has been used to attain surfaces with well-defined topographical features. The effect of augmenting the PS/PMMA solution with uniform 50 µm PS microspheres that can moderate the demixing process on the resultant surface features has also been investigated. The topographical features created here by spin coating under ambient air pressure conditions, rather than in nitrogen, which previous work reports, produces substrate surfaces with the ability to entrap vWF from flowing blood and facilitate platelet adhesion. The direct optical visualisation of fluorescently-labelled platelets indicates that topography resulting from inclusion of PS microspheres in the PS/PMMA spin coating solution increases the total number of platelets that adhere to the substrate surface over the period of the microfluidic assay. However, a detailed analysis of the adhesion rate, mean translocating velocity, mean translocation distance, and fraction of the stably adhered platelets measured during blood flow under arterial equivalent mechanical shear conditions indicates no significant difference for topographies created with or without inclusion of the PS microspheres.

Anorexia nervosa and the law: Legal mechanisms for involuntary treatment in Ireland

Anorexia nervosa is a form of eating disorder associated with significant morbidity and mortality, such that patients can become physically unwell and need medical treatment. Body image can be distorted, meaning that underweight people may believe they need to lose weight, leading to treatment refusal in some cases. Consequently, involuntary treatment is sometimes used in severe cases of anorexia, which may include nasogastric (tube) feeding to restore weight. Wardship is used in Ireland to obtain the court's consent for treatment of unwilling patients with anorexia nervosa, as it is legally uncertain whether mental health legislation can be applied for treatment of these patients. This article will explore the current legal mechanisms for involuntary treatment of anorexia nervosa in Ireland, analysing both wardship and mental health legislation.

Dynamic platelet function: A novel biomarker in inflammatory arthritis?

Background

Patients with inflammatory arthritis die prematurely of cardiovascular disease. Inflammation activates platelets. Since treatment of inflammatory arthritis is associated with reduced mortality, and decreased platelet reactivity reduces cardiovascular events, we hypothesised that platelet reactivity as measured by dynamic platelet function (DPF) would be increased in patients with inflammatory arthritis and that reactivity could be reduced with therapeutic intervention.

Objectives

To characterise platelet function using a validated physiological assay in patients with inflammatory arthritis before and after disease improvement.

Methods

22 patients were recruited and treated as per local protocol. DPF was measured at baseline and after clinical improvement. Video microscopy was utilised to measure dynamic platelet behaviour in microliters of blood perfused over von Willebrand factor (VWF) at arterial shear rates (1500 s-1). Motion-analysis software measured the number of platelets interacting with VWF, translocating across VWF, the speed and distance platelets travelled across VWF, and stably adhering to the surface. Platelet parameters at baseline and following improvement were compared using Wilcoxon signed rank test and paired student t-test. Changes in platelet function were correlated to inflammatory disease markers by Pearson Correlation.

Results

18 patients completed the study. Platelet adhesion decreased and platelet motion increased following treatment. Tender joint count correlated with platelet adhesion (Pearson r = 0.616, p≤0.01) while CRP correlated with velocity of platelet movement (Pearson r = 0.563, p≤0.01).

Conclusions

Improvement in clinical markers of inflammation is associated with a corresponding change in platelet function. Given the association between reduced mortality and decreased platelet reactivity our results suggest that an appropriate assay of platelet function could guide future therapy of patients with inflammatory arthritis.

Radial scars and complex sclerosing lesions on core needle biopsy of the breast: upgrade rates and long-term outcomes

PURPOSE

Radial scars and complex sclerosing lesions of the breast are part of a group of "indeterminate" breast lesions, which are excised due to risk of coexistent carcinoma. The aim of this study was to assess rate of upgrade of these lesions to invasive and in situ carcinoma and to quantify the risk of development of subsequent cancer in women diagnosed with these lesions.

METHODS

A retrospective review of a prospectively maintained breast screening database was performed. All patients with radial scar identified at either core biopsy or final excision biopsy between January 2006 and July 2012 were identified. Full pathological reports for both core biopsy and final excision biopsy were reviewed. Patient outcomes were followed for a mean of 117.1 months.

RESULTS

Of 451 B3 biopsies performed at our screening unit, 95 (22%) were found to have a radial scar or complex sclerosing lesion (CSL) on core needle biopsy. Within this group, 77 had no atypia on CNB, with 7 (9%) upgraded to invasive/in situ carcinoma on final excision. Of nine with definite atypia on CNB, 3 (33%) were upgraded. In those patients without atypia or malignancy on final excision, 7.5% developed cancer during 10-year follow-up.

CONCLUSION

Patients with radial scar with atypia have a higher risk of upgrade to malignancy. Further research is needed to identify which patients may safely avoid excision of radial scar. Patients with a diagnosis of radial scar on CNB are at increased subsequent risk of breast cancer and may benefit from additional screening.

Perioperative intravenous contrast administration and the incidence of acute kidney injury after major gastrointestinal surgery: prospective, multicentre cohort study

BACKGROUND

This study aimed to determine the impact of preoperative exposure to intravenous contrast for CT and the risk of developing postoperative acute kidney injury (AKI) in patients undergoing major gastrointestinal surgery.

METHODS

This prospective, multicentre cohort study included adults undergoing gastrointestinal resection, stoma reversal or liver resection. Both elective and emergency procedures were included. Preoperative exposure to intravenous contrast was defined as exposure to contrast administered for the purposes of CT up to 7 days before surgery. The primary endpoint was the rate of AKI within 7 days. Propensity score-matched models were adjusted for patient, disease and operative variables. In a sensitivity analysis, a propensity score-matched model explored the association between preoperative exposure to contrast and AKI in the first 48 h after surgery.

RESULTS

A total of 5378 patients were included across 173 centres. Overall, 1249 patients (23·2 per cent) received intravenous contrast. The overall rate of AKI within 7 days of surgery was 13·4 per cent (718 of 5378). In the propensity score-matched model, preoperative exposure to contrast was not associated with AKI within 7 days (odds ratio (OR) 0·95, 95 per cent c.i. 0·73 to 1·21; P = 0·669). The sensitivity analysis showed no association between preoperative contrast administration and AKI within 48 h after operation (OR 1·09, 0·84 to 1·41; P = 0·498).

CONCLUSION

There was no association between preoperative intravenous contrast administered for CT up to 7 days before surgery and postoperative AKI. Risk of contrast-induced nephropathy should not be used as a reason to avoid contrast-enhanced CT.

Identification of physicochemical properties that modulate nanoparticle aggregation in blood

Inorganic materials are receiving significant interest in medicine given their usefulness for therapeutic applications such as targeted drug delivery, active pharmaceutical carriers and medical imaging. However, poor knowledge of the side effects related to their use is an obstacle to clinical translation. For the development of molecular drugs, the concept of safe-by-design has become an efficient pharmaceutical strategy with the aim of reducing costs, which can also accelerate the translation into the market. In the case of materials, the application these approaches is hampered by poor knowledge of how the physical and chemical properties of the material trigger the biological response. Hemocompatibility is a crucial aspect to take into consideration for those materials that are intended for medical applications. The formation of nanoparticle agglomerates can cause severe side effects that may induce occlusion of blood vessels and thrombotic events. Additionally, nanoparticles can interfere with the coagulation cascade causing both pro- and anti-coagulant properties. There is contrasting evidence on how the physicochemical properties of the material modulate these effects. In this work, we developed two sets of tailored carbon and silica nanoparticles with three different diameters in the 100-500 nm range with the purpose of investigating the role of surface curvature and chemistry on platelet aggregation, activation and adhesion. Substantial differences were found in the composition of the protein corona depending on the chemical nature of the nanoparticles, while the surface curvature was found to play a minor role. On the other hand, large carbon nanoparticles (but not small carbon nanoparticles or silica nanoparticles) have a clear tendency to form aggregates both in plasma and blood. This effect was observed both in the presence or absence of platelets and was independent of platelet activation. Overall, the results presented herein suggest the existence of independent modes of action that are differently affected by the physicochemical properties of the materials, potentially leading to vessel occlusion and/or formation of thrombi in vivo.

Meta-analysis of the impact of progesterone receptor status on oncological outcomes in oestrogen receptor-positive breast cancer

BACKGROUND

Assessment of the oestrogen receptor (ER) provides important prognostic information in breast cancer. The impact of progesterone receptor (PgR) status is less clear. Standardization of immunohistochemical analysis of these receptors has reduced interstudy heterogeneity. The aim of this meta-analysis was to evaluate the impact of PgR negativity on outcomes in ER-positive (ER+) breast cancer.

METHODS

This study was performed according to PRISMA and MOOSE guidelines. PubMed, Embase and the Cochrane Library were searched systematically to identify studies comparing disease-free survival as the primary outcome and overall survival as secondary outcome between PgR-positive (PgR+) and PgR-negative (PgR-) status in ER+ breast cancer. A meta-analysis of time-to-effect measures from included studies was undertaken.

RESULTS

Eight studies including 13 667 patients, 11 838 in the ER+PgR+ group and 1829 in the ER+PgR- group, met the inclusion criteria. Treatment characteristics did not differ significantly between the two groups. Patients in the ER+PgR- group had a higher risk of disease recurrence than those who had ER+PgR+ disease (hazard ratio (HR) 1·57, 95 per cent c.i. 1·38 to 1·79; P < 0·001). This hazard was increased in patients with human epidermal growth factor receptor 2-negative tumours (HR 1·62, 1·37 to 1·93; P < 0·001). A similar result was observed for overall survival (HR 1·69, 1·33 to 2·14; P < 0·001).

CONCLUSION

PgR negativity is associated with significant reductions in disease-free and overall survival in ER+ breast cancer. Treatment and surveillance strategies in these patients should be tailored accordingly.

In Vitro Measurement and Modeling of Platelet Adhesion on VWF-Coated Surfaces in Channel Flow

The process of platelet adhesion is initiated by glycoprotein (GP)Ib and GPIIbIIIa receptors on the platelet surface binding with von Willebrand factor on the vascular walls. This initial adhesion and detachment of a single platelet is a complex process that involves multiple bonds forming and breaking and is strongly influenced by the surrounding blood-flow environment. In addition to bond-level kinetics, external factors such as shear rate, hematocrit, and GPIb and GPIIbIIIa receptor densities have also been identified as influencing the platelet-level rate constants in separate studies, but this still leaves a gap in understanding between these two length scales. In this study, we investigate the fundamental relationship of the dynamics of platelet adhesion, including these interrelating factors, using a coherent strategy. We build a, to our knowledge, novel and computationally efficient multiscale model accounting for multibond kinetics and hydrodynamic effects due to the flow of a cellular suspension. The model predictions of platelet-level kinetics are verified by our microfluidic experiments, which systematically investigate the role of each external factor on platelet adhesion in an in vitro setting. We derive quantitative formulas describing how the rates of platelet adhesion, translocation, and detachment are defined by the molecular-level kinetic constants, the local platelet concentration near the reactive surface determined by red-blood-cell migration, the platelet effective reactive area due to its tumbling motion, and the platelet surface receptor density. Furthermore, if any of these aspects involved have abnormalities, e.g., in a disease condition, our findings also have clinical relevance in predicting the resulting change in the adhesion dynamics, which is essential to hemostasis and thrombosis.

Trends in the Use of Laparoscopic Versus Open Paediatric Appendicectomy: A Regional 12-Year Study and a National Survey

BACKGROUND

In adult patients, it is generally accepted that laparoscopic appendicectomy (LA) is the predominant operative pathway in treating acute appendicitis. The case for a similar pathway utilising LA in children is less clear. We investigate usage, trends and complications after LA in children in a single co-located adult/paediatric centre with contemporaneous adults as controls.

METHODS

A retrospective case-control study was conducted over 12 years including patients who underwent appendicectomy, and the paediatric series (<16 years) was divided into age-groups-based quartiles. An anonymous questionnaire-based national survey was circulated among general and paediatric surgeons.

RESULTS

Of the 5784 appendicectomy patients, 2960 were children. LA rate in paediatric appendicitis was 65%. Yearly trends in LA reached a steady state in both groups after 2010 (Δ 0-1%/year). Rates of LA and LA IAA (respectively) differed significantly between age groups: 60, 3% (0-9 years); 65, 1% (10-13 years); 71, 2% (14-16 years) and 93, 3% (>16 years) (p = 0.001, 0.02). The national survey showed respondents believed LA was not superior to OA in paediatric patients except in terms of cosmesis. There was strong support in the use of LA in older children and children >40 kg.

CONCLUSION

The use of LA in paediatric appendicectomies in the study region is similar to international rates, but not increasing over time. Irish surgeons still favour OA in younger children and prefer a case-by-case approach rather LA being the preferred pathway. This is despite the regional and international evidence showing favourable outcomes with LA in children.

Dynamic platelet function is markedly different in patients with cancer compared to healthy donors

Despite a fivefold increased risk of thromboembolism in patients with cancer, the mechanism of arterial thromboembolism is poorly understood. To address this, we investigated platelet function in cancer patients and healthy controls using an assay that mimics the arterial vasculature. Blood samples from cancer patients (n = 36) and healthy controls (n = 22) were perfused through custom-made parallel-plate flow chambers coated with von Willebrand factor (VWF) under arterial shear (1,500 s^-1). Multiparameter measurements of platelet interactions with the immobilized VWF surface were recorded by digital-image microscopy and analyzed using custom-designed platelet-tracking software. Six measured parameters that characterize in detail the surface motion and surface binding of several hundred platelets per blood sample differed significantly in those with cancer from the healthy donors. In particular, it was found that patients with cancer had decreased numbers of platelets interacting, translocating and adhering to VWF. There were also reductions in the speed and distances that platelets traveled on VWF in comparison to healthy controls. Platelet function differed between those with early-stage cancer compared to those with later stage cancer. Patients with advanced cancer had an increased number of platelets stably adhering to VWF and greater platelet surface coverage after a given time of interaction. To the best of our knowledge, our results demonstrate for the first time that dynamic platelet function is markedly different in patients with cancer compared to healthy donors.

Entrapment of Autologous von Willebrand Factor on Polystyrene/Poly(methyl methacrylate) Demixed Surfaces

Human platelets play a vital role in haemostasis, pathological bleeding and thrombosis. The haemostatic mechanism is concerned with the control of bleeding from injured blood vessels, whereby platelets interact with the damaged inner vessel wall to form a clot (thrombus) at the site of injury. This adhesion of platelets and their subsequent aggregation is dependent on the presence of the blood protein von Willebrand Factor (vWF). It is proposed here that the entrapment of vWF on a substrate surface offers the opportunity to assess an individual’s platelet function in a clinical diagnostic context. Spin coating from demixed solutions of polystyrene (PS) and poly(methyl methacrylate) (PMMA) onto glass slides has been shown previously to support platelet adhesion but the mechanism by which this interaction occurs, including the role of vWF, is not fully understood. In this work, we report a study of the interaction of platelets in whole blood with surfaces produced by spin coating from a solution of a weight/weight mixture of a 25% PS and 75% PMMA (25PS/75PMMA) in chloroform in the context of the properties required for their use as a Dynamic Platelet Function Assay (DPFA) substrate. Atomic Force Microscopy (AFM) indicates the presence of topographical features on the polymer demixed surfaces in the sub-micron to nanometer range. X-ray Photoelectron Spectroscopy (XPS) analysis confirms that the uppermost surface chemistry of the coatings is solely that of PMMA. The deliberate addition of various amounts of 50 μm diameter PS microspheres to the 25PS/75PMMA system has been shown to maintain the PMMA chemistry, but to significantly change the surface topography and to subsequently effect the scale of the resultant platelet interactions. By blocking specific platelet binding sites, it has been shown that their interaction with these surfaces is a consequence of the entrapment and build-up of vWF from the same whole blood sample.

Increased platelet reactivity as measured by plasma glycoprotein VI in gout

Patients with gout have an increased risk of cardiovascular events. The glycoprotein VI (GPVI) receptor is found exclusively on platelets and megakaryocytes, is proteolytically cleaved upon platelet activation, and detectable in plasma as soluble GPVI (sGPVI). Therefore, elevated sGPVI is a marker of platelet activation and a risk marker for cardiovascular events. The aim of this study was to assess platelet activation, as measured by plasma sGPVI level in gout. Blood samples were taken from patients with gout or osteoarthritis, and from healthy volunteers. Demographic and clinical data were collected for all participants. Blood samples were processed as double-spun platelet-poor plasma. Plasma sGPVI levels were measured using enzyme-linked immunosorbent assay. Mann-Whitney U test was used to compare groups. In total, 91 patients were included, 27 during gout flare, 41 with intercritical gout, 23 with osteoarthritis, and 53 healthy controls. Median (interquartile range) sGPVI levels were 6.51 ng/mL (4.52, 8.41) in gout flare, 3.58 ng/mL (2.11, 5.55) in intercritical gout, 2.73 ng/mL (2.17, 3.72) in osteoarthritis, and 2.19 ng/mL (1.72, 3.31) in healthy controls. Plasma sGPVI levels in both gout groups were significantly increased compared to healthy controls (p < 0.005 for each), in gout flare compared to osteoarthritis (p < 0.005), and in gout flare compared to intercritical gout (p = 0.001). There was no significant difference in sGPVI levels in gout patients with and without tophi or in those prescribed colchicine. We conclude that patients with gout exhibit platelet hyperactivity as demonstrated by elevated sGPVI levels. Platelet activation is exacerbated in gout, especially during gout flares.

Platelet behaviour on von Willebrand Factor changes in pregnancy: Consequences of haemodilution and intrinsic changes in platelet function

Platelet function in pregnancy is poorly understood. Previous studies of platelet function in pregnancy have used non-physiological assays of platelet function with conflicting results. This study using a physiological assay of platelet function investigated platelet interactions with von Willebrand Factor (VWF) in blood from healthy pregnant women and healthy non-pregnant controls. Blood samples (200 µl) from third-trimester pregnancies (n = 21) and non-pregnant controls (n = 21) were perfused through custom-made parallel-plate flow chambers coated with VWF under arterial shear (1,500 s⁻¹). Multi-parameter measurements of platelet interactions with the immobilized VWF surface were recorded by digital-image microscopy and analysed using custom-designed platelet-tracking software. Platelet interactions with VWF decreased in healthy third-trimester pregnant participants relative to controls. This effect is most likely due to haemodilution which occurs physiologically during pregnancy. Interestingly, platelets in blood from pregnant participants translocated more slowly on VWF under arterial-shear conditions. These decreases in platelet translocation speed were independent of haemodilution, suggesting intrinsic changes in platelet function with pregnancy.

Brief Report: Genetic Variation of the α1 -Antitrypsin Gene Is Associated With Increased Autoantibody Production in Rheumatoid Arthritis

OBJECTIVE

To examine the prevalence of α₁ -antitrypsin deficiency (AATD) in rheumatoid arthritis (RA), and to determine whether AATD is associated with higher levels of rheumatoid factor (RF), antinuclear antibodies (ANAs), and anti-citrullinated peptide autoantibodies (ACPAs).

METHODS

RF, ANAs, and ACPAs were measured by standard immunoturbidimetry, immunofluorescence assay, and enzyme-linked immunosorbent assay, respectively. Characterization of AAT phenotypes was performed by isoelectric focusing and immunofixation. The chi-square test with Yates' correction and the Mann-Whitney U test were used to assess the prevalence of alleles associated with AATD in RA and to compare mean antibody titers, respectively.

RESULTS

Of 246 patients with RA, 24 who were heterozygous for AATD were identified, with no statistically significant difference in the prevalence of AATD between RA patients and the general population (P = 0.39). A positive association between heterozygosity for AATD and the production of ACPAs was observed (P < 0.0001), with increased ACPA titers recorded in the AATD RA cohort compared with the general population (P = 0.01).

CONCLUSION

AAT heterozygous status in RA is strongly associated with positive ACPAs and may define a distinct subset of patients with increased disease severity.

Increased soluble GPVI levels in cirrhosis: evidence for early in vivo platelet activation

Cirrhosis is a consequence of prolonged liver injury and is characterised by extensive tissue fibrosis: the deposition of collagen-rich extracellular matrix. The haemostatic balance is disordered in cirrhosis and coagulation activation appears to promote fibrosis. In spite of recent studies demonstrating a role for anticoagulant therapy in preventing cirrhosis progression, there has not been a change in clinical practice, suggesting that physicians are reluctant to anticoagulate patients with cirrhosis due to bleeding risks. Platelets play an important role in facilitating coagulation. Glycoprotein VI (GPVI) is a platelet-specific collagen receptor that is shed from the platelet surface in a metalloproteinase-dependent manner in response to GPVI ligation and coagulation activation. Our aim was to use soluble GPVI levels to determine whether there was evidence for collagen and coagulation-induced platelet activation in early, well-compensated cirrhosis. Plasma soluble GPVI levels were quantified in 46 patients with mixed aetiology cirrhosis and 55 healthy controls using an immunoassay. In the cirrhosis group, soluble GPVI levels were significantly increased (5.8 ± 4.4 ng/ml, n = 46) compared to healthy controls (3.3 ± 3.4 ng/ml, n = 55, p < 0.05). This increase in soluble GPVI levels was still evident when levels were adjusted for platelet count (Healthy controls; 0.015 ± 0.018 ng/10⁶ platelets/ml vs. cirrhosis; 0.048 ± 0.04 ng/10⁶ platelets/ml, p < 0.0001). This study provides evidence for early platelet activation in patients with well-compensated cirrhosis. This may have translational implications for prognosis, treatment, and risk stratification.

Normal Tissue Complication Probability (NTCP) Modelling of Severe Acute Mucositis using a Novel Oral Mucosal Surface Organ at Risk

AIMS

A normal tissue complication probability (NTCP) model of severe acute mucositis would be highly useful to guide clinical decision making and inform radiotherapy planning. We aimed to improve upon our previous model by using a novel oral mucosal surface organ at risk (OAR) in place of an oral cavity OAR.

MATERIALS AND METHODS

Predictive models of severe acute mucositis were generated using radiotherapy dose to the oral cavity OAR or mucosal surface OAR and clinical data. Penalised logistic regression and random forest classification (RFC) models were generated for both OARs and compared. Internal validation was carried out with 100-iteration stratified shuffle split cross-validation, using multiple metrics to assess different aspects of model performance. Associations between treatment covariates and severe mucositis were explored using RFC feature importance.

RESULTS

Penalised logistic regression and RFC models using the oral cavity OAR performed at least as well as the models using mucosal surface OAR. Associations between dose metrics and severe mucositis were similar between the mucosal surface and oral cavity models. The volumes of oral cavity or mucosal surface receiving intermediate and high doses were most strongly associated with severe mucositis.

CONCLUSIONS

The simpler oral cavity OAR should be preferred over the mucosal surface OAR for NTCP modelling of severe mucositis. We recommend minimising the volume of mucosa receiving intermediate and high doses, where possible.

Platelet aggregation in response to ADP is highly variable in normal donors and patients on anti-platelet medication

BACKGROUND

P2Y12 inhibitors are indicated in patients following percutaneous coronary intervention. Several studies have demonstrated that high on treatment platelet reactivity is correlated with outcomes yet prospective studies of guided therapy have failed to show benefit. There is a paucity of studies on the platelet aggregation response to ADP before P2Y12 therapy is started. The aim of this study was to characterize platelet responses to 20 μM ADP by light transmission aggregometry (LTA) in a homogenous population.

METHODS

Platelet aggregation was assessed in 201 patients on dual antiplatelet therapy, 98 patients on aspirin alone and 47 normal, healthy volunteers free from anti-platelet medication.

RESULTS

Consensus guidelines suggest that a platelet aggregation response in response to the agonist ADP of <57% is an adequate therapeutic response to P2Y12 inhibition. Seven healthy donors and 38 patients taking aspirin only had aggregation responses below 57%.

CONCLUSIONS

The results of our study demonstrate that 15% of normal donors and 38% of patients taking aspirin only would be classified as having a therapeutic response to P2Y12 inhibition using current guidelines.

A review of anaesthetic outcomes in patients with genetically confirmed mitochondrial disorders

Mitochondrial disorders are a clinically and biochemically diverse group of disorders which may involve multiple organ systems. General anaesthesia (GA) poses a potential risk of decompensation in children with mitochondrial disorders, and there is little guidance for anaesthetists and other clinicians regarding the optimal anaesthetic agents and perioperative management to provide to patients with mitochondrial disease[15]. The aim of this review was to document adverse events and perioperative complications from GA in patients with genetically confirmed mitochondrial disorders. A retrospective chart review of patients with genetically confirmed mitochondrial disorders who had undergone GA was undertaken. The indication for GA, anaesthetic agents utilised, length of admission and post anaesthetic complications were documented and analysed. Twenty-six patients with genetically proven mitochondrial disease underwent 65 GAs. Thirty-four (52%), received propofol as their induction agent. Thirty-three (51%) patients received sevoflurane for the maintenance of anaesthesia, while 8 (12%) received isoflurane and 24 (37%) received propofol. The duration of most GAs was short with 57 (87%) lasting less than 1 h. Perioperative complications occurred in five patients while under GA including ST segment depression, hypotension and metabolic acidosis in one. All five patients were stabilised successfully and none required ICU admission as a consequence of their perioperative complications. The duration of hospital stay post GA was <24 h in 25 (38%) patients.

CONCLUSION

No relationship between choice of anaesthetic agent and subsequent perioperative complication was observed. It is likely that individual optimisation on a case-by-case basis is more important overall than choice of any one particular technique. What is Known: • General anaesthesia (GA) poses a potential risk of decompensation in children with mitochondrial disorders. • There is a great diversity in the anaesthetic approaches undertaken in this cohort, and little guidance exists for anaesthetists and other clinicians regarding the optimal anaesthetic agents and perioperative management to provide to patients with mitochondrial disease. What is New: • In this study of 26 patients with genetically confirmed mitochondrial disease who underwent 65 GAs, no relationship between choice of anaesthetic agent and subsequent perioperative complication was observed • It is likely that individual optimisation on a case-by-case basis is more important overall than choice of any one particular technique.

Computational Tracking of Shear-Mediated Platelet Interactions with von Willebrand Factor

The imaging of shear-mediated dynamic platelet behavior interacting with surface-immobilized von Willebrand factor (vWF) has tremendous potential in characterizing changes in platelet function for clinical diagnostics purposes. However, the imaging output, a series of images representing platelets adhering and rolling on the surface, poses unique, non-trivial challenges for software algorithms that reconstruct the positional trajectories of platelets. We report on an algorithm that tracks platelets using the output of such flow run experiments, taking into account common artifacts encountered by previously-published methods, and we derive seven key metrics of platelet dynamics that can be used to characterize platelet function. Extensive testing of our method using simulated platelet flow run data was carried out to validate our tracking method and derived metrics in capturing key platelet-vWF interaction-dynamics properties. Our results show that while the number of platelets present on the imaged area is the leading cause of errors, flow run data from two experiments using whole blood samples showed that our method and metrics can detect platelet property changes/differences that are concordant with the expected biological outcome, such as inhibiting key platelet receptors such as P2Y₁, glycoprotein (GP)Ib and GPIIb/IIIa. These findings support the use of our methodologies to characterize platelet function among a wide range of healthy and disease cohorts.

Abstracts from the 5th International Conference for Healthcare and Medical Students (ICHAMS)

O1: Assessing the protective effect of dexrazoxane against doxorubicin-induced toxicity in HL-1 cardiomyocytes

Yvonne Sweeney, Hugh O’Neill, Garry Duffy

O2: Role of KCNQ1 in epithelial barrier repair

Daniel Creegan, Viviana Bustos, Brian J. Harvey

O3: The suitability of non-small cell lung cancer cytology preparations for the analysis of anaplastic lymphoma kinase gene rearrangements

Alexander Dalphy, Anthony O’Grady, Elaine Kay

O4: Penetrating keratoplasty and descemet’s stripping automated endothelial keratoplasty may lead to deterioration in glaucoma management

Katarzyna Samelska, Justyna Izdebska, Anna Kurowska

O5: The effect of Resolvin D1 on normal and cystic fibrosis human bronchial epithelium

Rena Al-Zubaidy, Magdalena Mroz, Brian Harvey

O6: Validity of clinical assessment compared with plantar fascia thickness on ultrasound for plantar fasciitis: a cross-sectional study

Ryan Fagan, Helen French, Vanessa Cuddy, Jennifer Ashton, Michelle Clarke

P1: Undergraduate medical research in Gulf Cooperation Council (GCC) countries: A descriptive study of students’ views

Zaid Sayedalamin, Mukhtiar Baig, Osama Almutairi, Hassan Allam, Taher F. Halawa, Hazem M. Atta

P2: Positive fluid balance as a prognostic factor in children with sepsis during first 3 hours of resuscitation in intensive care unit

Linda Sirone, Renars Erts, Jana Pavare

P3: Patients on aspirin: Too little or too much?

Louis Richter, Joseph Morris, Irene Oglesby, Eimear Dunne, Dermot Kenny

P4: Beta catenin/TCF4 activation reduces KCNQ1 current in colonic monolayers

Ibrahim Mohammed Mahdi Khayyat, Viviana Bustos Salgado, Brian J. Harvey

P5: Size Matters. Abdominal aortic aneurysm: adherence to surveillance imaging guidelines

Jonavan Tan, Daragh Moneley, Austin Leahy, Patricia Fitzgerald

P6: Endoscopic retrograde cholangiopancreatography in the west of Ireland: Procedural outcomes and peri-procedural complications

Evelyn Fennelly, Grace Harkin, John Lee

P7: The effect of the extracellular redox environment on polyamine-platelet interactions

Erica O’Sullivan, Brian Kirby, Sarah O’Neill

P8: Functionalized gold nanoparticles: preliminary data on in vitro toxicity and comparative photothermal effect

Diana Gonciar, Teodora Mocan, Cristian Matea, Lucian Mocan, Cornel Iancu

P9: Imaging proteasomal inhibition after seizures in the brain: A study into cellular activity in the hippocampus of epileptic transgenic mice

Chloe Doran, Sarah Hoolahan, Tobias Engel

P10: Investigating the ability of the Olfactory epithelial stem cells to differentiate into glial cells by assessing cell morphology and marker expression

Maha Alkhattab, Tijna Alekseeva, William Lackington, Fergal O’Brien

P11: Beaumont Hospital cystic fibrosis service audit and annual report

Nabeehah Moollan, Chloe Doran, Noel Gerry McElvaney, Cedric Gunaratnam

P12: Quick cognitive screening: the 6-item cognitive impairment test and the temporal orientation score

Lorraine Scanlon, Noeleen Brady, Suzanne Timmons

P13: Granular analysis of causes of peritoneal dialysis technique failure in the first six months of therapy

Richard Bresler, Zita Abreu, Stefan Trohonel, Joanne Bargman

P14: Job satisfaction of surgeons working in hajj pilgrimage: a multicenter study

Ahmad A. Mirza, Ahmed Badrek-Amoudi, Rakan H. Aun, Hussam A. Senan, Abdulrahim A. Mirza, Mohammed S. Binsaad, Mian U. Farooq

P15: Investigation of the role of Bok using wild-type, bax-, bok-, and bax/bok-double-deficient mice

Saheli Nandi, Beatrice D’Orsi, Jochen Prehn

P16: Is it possible to predict resistance of an organism to stress based on the level of corticosterone?

Mariia Zharova, Pavel Umrukhin

P17: Investigating the strength model of self-regulation (ego depletion) and medical decision making and error in medical students

Wendy Evans-Uhegbu, Frank Doyle, Hope Kudryashova, Derek Dorris, Anthony Cummins

P18: Does bladder drainage with intermittent catheterisation preserve kidney function in boys with posterior urethral valves?

Jemma Doheny-Shanley, Mark Woodward, Wesley Hayes

P19: Investigating the role of Stonin 2, a Clathrin Mediated Endocytosis adaptor protein, in altered hippocampal synaptic transmission characterized in schizophrenia

Marina Yostos, David Cotter, Melanie Focking

P20: Predicting complications after colon resection

Samantha Stancu, Florin Iordache, Bogdan A. Popescu

P21: Knowledge, attitude and practice of the methods of primary and secondary prevention of cervical cancer among NYSC members in Lagos state, Nigeria

Muhammad-Mujtaba A. Akanmu, Alero A. Robert, Ezekiel O. Oridota

P22: Incidental glucose and lipid metabolisms disorders among office workers: a cross sectional study

Ahmad A. Mirza, Ali K. Alzahrani, Omar Alfarhan, Essam Nour Eldin

P23: Differentiating clinically significant spinal injuries; a review of emergency department presentations

Bronagh MacManus, Owen Keane, Patrick Hillery, James Lee, Hugh O’Reilly, Niamh Collins

P24: Pattern of renal colic occurrence due to urinary stones during Ramadan and other months of the year at King Abdulaziz Medical City, Riyadh, KSA

Ibrahim Abu saq, Abdullah Al Mufarrih, Muath Jaafari, Abdullah Al Mahayni, Amen Bawazir, Sultan Alkhateeb

P25: Proteomic analysis reveals novel AIB1 co-factors that may contribute to acquired endocrine resistance in breast cancer

Amenah Dhannoon, Damir Vareslija, Arnold Hill, Leonie Young

P26: Improving sedation practice in general ICU in Beaumont Hospital

Declan Donoghue, Criona Walsh, Aileen McCabe, John Pope, Saturnino Pasco, Caroline Fallon, Don Solanki, Fiona Kiernan, Sinead Galvin, Jquan Mucvimicc, Johanna Mulvihill

P27: Diagnosis and control of hypertension as indicators of the level of awareness among relatives of medical students

Ahmad A. Mirza, Soha A. Elmosry

P28: Evaluation of the antitumor potential from extracts of endemic plants of Brazilian caatinga against melanoma and hepatocarcinoma

Lorenza Andres Ameida De Souza, Yuri de Oliveira, Diego Menezes, Alene Vanessa Santos

P29: The role of Chromogranin A as a biomarker in drug resistant neuroblastoma

Ahmad Zaki Asraf, Raymond Stallings, Olga Piskareva, Ross Conlon

P30: Membrane sweep at term gestation in CUMH; a case-control study

Siún Sweeney-Landers, Cathy Burke

P31: Study of the variability of glucose levels in patients with diabetes undergoing continuous glucose monitoring

Paraic Behan, Seamus Sreenan

P32: Inflammatory cytokine response to decreased plasma alpha-1 antitrypsin levels in individuals with the MZ genotype

Ahmed Organjee, Tatsiana Crosbie-Staunton, Emer Reeves, Noel McElvaney

P33: Analysing the role of SRC-1 in breast cancer stem cell formation and activity

Crystal Mieres, Leonie Young, Sara Charmsaz

P34: Screening Streptococcus pneumoniae isolates for virulence genes

Aya Al-Jalamdeh, Mary Corcoran, Martha McElligott, Niall Stevens, Hilary Humphreys

P35: Assessment of the relevance of admission clerking criteria taught to medical students at King Abdulaziz University to real hospital practice

Rashid Barnawi, Abdulaziz Ghurab, Sultan Alfaer, Hassan Balubaid, Kamal Hanbazazah, Mohammed Bukhari

P36: Pattern of emergency department visits during Hajj period

Mohammed Alsakkaf, Ahmad Mirza, Amrallah Mohammed

P37: Anti-Dengue activity of Aspergillus terreus (sulochrin); An in vitro study

Anastasia Pratanata, Maria Nathania, Tsabita Annisa, Beti Dewi

P38: The comorbidome in alpha-1 antitrypsin deficiency

Kuok Zhen Lee, Tomas P. Carroll, Laura Fee, Noel G. McElvaney

P39: MLO-Y4 cells behave more like osteocytes in response to mechanical stimulation when cultured in 3D

Rachel C. White, Robert T Brady, Fergal O’Brien

Efficacy of vacuum erectile devices (VEDs) after radical prostatectomy: the initial Irish experience of a dedicated VED clinic

Controversy exists regarding optimal penile rehabilitation program following radical prostatectomy (RP). Vacuum erectile devices (VEDs) have become an important component of penile rehabilitation protocols. The aim of this study was to assess the efficacy and patient satisfaction of a dedicated VED clinic. A voluntary telephone questionnaire was performed of all patients who attended a VED clinic to date in two university teaching hospitals. Patient demographics, histopathological characteristics and functional status (International Index of Erectile Function (IIEF) scores) were obtained from a retrospective review of a prospectively maintained database. Sixty-five men attended the dedicated VED clinic in the two university teaching hospitals. Forty-men (76.3%) men purchased a VED following the dedicated clinic. There was significant differences noted between the mean preoperative and the 3-month postoperative IIEF scores (22.08±3.16 vs 11.3±3.08, P=0.0001) and between the 3-month postoperative IIEF score and the post-VED use IIEF score (11.3±3.08 vs 16.74±2.62, P=0.0001). Despite VED use, there was a significant reduction in erectile function from presurgery status (22.08±3.16 vs 16.74±2.62, P=0.0001). All patients reported that the dedicated VED was helpful and would recommend it to other patients. Our study demonstrates that, despite a reduction in erectile function after RP, successful erections are attainable with a VED. There is potential and need for the development of a standard penile rehabilitation program and treatment of ED after RP internationally.

Factors controlling volatile organic compounds in dwellings in Melbourne, Australia

This study characterized indoor volatile organic compounds (VOCs) and investigated the effects of the dwelling characteristics, building materials, occupant activities, and environmental conditions on indoor VOC concentrations in 40 dwellings located in Melbourne, Australia, in 2008 and 2009. A total of 97 VOCs were identified. Nine VOCs, n-butane, 2-methylbutane, toluene, formaldehyde, acetaldehyde, d-limonene, ethanol, 2-propanol, and acetic acid, accounted for 68% of the sum of all VOCs. The median indoor concentrations of all VOCs were greater than those measured outdoors. The occupant density was positively associated with indoor VOC concentrations via occupant activities, including respiration and combustion. Terpenes were associated with the use of household cleaning and laundry products. A petroleum-like indoor VOC signature of alkanes and aromatics was associated with the proximity of major roads. The indoor VOC concentrations were negatively correlated (P < 0.05) with ventilation. Levels of VOCs in these Australian dwellings were lower than those from previous studies in North America and Europe, probably due to a combination of an ongoing temporal decrease in indoor VOC concentrations and the leakier nature of Australian dwellings.

The effect of initiation of antiretroviral therapy on monocyte, endothelial and platelet function in HIV-1 infection

OBJECTIVES

Monocyte activation, endothelial dysfunction and platelet activation all potentially contribute to the increased risk of cardiovascular disease (CVD) reported in those with HIV-1 infection. To date, no study has examined how initiation of antiretroviral therapy (ART) affects markers of all three processes. We aimed to compare markers of monocyte, endothelial and platelet function between untreated HIV-positive subjects and HIV-negative controls and to examine the early effects of ART initiation on these markers.

METHODS

We measured monocyte [soluble CD14 (sCD14) and sCD163], endothelial [von Willebrand factor (vWF), intercellular adhesion molecule-1 (ICAM-1) and vascular adhesion molecule-1 (VCAM-1)] and platelet [soluble P-selectin (sP-selectin), soluble CD40 ligand (sCD40L) and soluble glycoprotein VI (sGPVI)] biomarkers before and at weeks 4 and 12 post ART initiation in HIV-positive and well-matched HIV-negative controls.

RESULTS

We examined 40 subjects, 25 HIV-positive subjects and 15 controls, with a median age of 34 years [interquartile range (IQR) 31, 40 years], of whom 60% were male and 47.5% Caucasian. Pre-ART, all biomarkers (monocyte, endothelial and platelet) were significantly higher in HIV-positive patients versus controls (all P < 0.05) and decreased with ART initiation, except for sCD14, which remained unchanged [median 1680 (IQR 1489, 1946) ng/mL at week 12 versus 1570 (IQR 1287, 2102) ng/mL at week 0; P = 0.7]. Although platelet activation markers reduced to levels comparable to those in controls, endothelial dysfunction markers remained elevated, as did sCD163 [at week 12, median 1005 (IQR 791, 1577) ng/mL in HIV-positive patients versus 621 (IQR 406, 700) ng/mL in controls; P < 0.0001].

CONCLUSIONS

ART initiation resulted in reductions in levels of CVD-associated biomarkers; however, although they improved, markers of endothelial dysfunction and monocyte activation remained elevated. How these persistent abnormalities affect CVD risk in HIV infection remains to be determined.

Increased Thrombopoiesis and Platelet Activation in Hantavirus-Infected Patients

BACKGROUND

Thrombocytopenia is a common finding during viral hemorrhagic fever, which includes hemorrhagic fever with renal syndrome (HFRS). The 2 main causes for thrombocytopenia are impaired thrombopoiesis and/or increased peripheral destruction of platelets. In addition, there is an increased intravascular coagulation risk during HFRS, which could be due to platelet activation.

METHODS

Thrombopoiesis was determined by quantification of platelet counts, thrombopoietin, immature platelet fraction, and mean platelet volume during HFRS. The in vivo platelet activation was determined by quantification of soluble P-selectin (sP-selectin) and glycoprotein VI (sGPVI). The function of circulating platelets was determined by ex vivo stimulation followed by flow cytometry analysis of platelet surface-bound fibrinogen and P-selectin exposure. Intravascular coagulation during disease was determined by scoring for disseminated intravascular coagulation (DIC) and recording thromboembolic complications.

RESULTS

The levels of thrombopoietin, immature platelet fraction, and mean platelet volume all indicate increased thrombopoiesis during HFRS. Circulating platelets had reduced ex vivo function during disease compared to follow-up. Most interestingly, we observed significantly increased in vivo platelet activation in HFRS patients with intravascular coagulation (DIC and thromboembolic complications) as shown by sP-selectin and sGPVI levels.

CONCLUSIONS

HFRS patients have increased thrombopoiesis and platelet activation, which contributes to intravascular coagulation.

Molecular understanding of sulphuric acid-amine particle nucleation in the atmosphere

Nucleation of aerosol particles from trace atmospheric vapours is thought to provide up to half of global cloud condensation nuclei. Aerosols can cause a net cooling of climate by scattering sunlight and by leading to smaller but more numerous cloud droplets, which makes clouds brighter and extends their lifetimes. Atmospheric aerosols derived from human activities are thought to have compensated for a large fraction of the warming caused by greenhouse gases. However, despite its importance for climate, atmospheric nucleation is poorly understood. Recently, it has been shown that sulphuric acid and ammonia cannot explain particle formation rates observed in the lower atmosphere. It is thought that amines may enhance nucleation, but until now there has been no direct evidence for amine ternary nucleation under atmospheric conditions. Here we use the CLOUD (Cosmics Leaving OUtdoor Droplets) chamber at CERN and find that dimethylamine above three parts per trillion by volume can enhance particle formation rates more than 1,000-fold compared with ammonia, sufficient to account for the particle formation rates observed in the atmosphere. Molecular analysis of the clusters reveals that the faster nucleation is explained by a base-stabilization mechanism involving acid-amine pairs, which strongly decrease evaporation. The ion-induced contribution is generally small, reflecting the high stability of sulphuric acid-dimethylamine clusters and indicating that galactic cosmic rays exert only a small influence on their formation, except at low overall formation rates. Our experimental measurements are well reproduced by a dynamical model based on quantum chemical calculations of binding energies of molecular clusters, without any fitted parameters. These results show that, in regions of the atmosphere near amine sources, both amines and sulphur dioxide should be considered when assessing the impact of anthropogenic activities on particle formation.

ITAM receptor-mediated generation of reactive oxygen species in human platelets occurs via Syk-dependent and Syk-independent pathways

BACKGROUND

Ligation of the platelet-specific collagen receptor, GPVI/FcRγ, causes rapid, transient disulfide-dependent homodimerization, and the production of intracellular reactive oxygen species (ROS) generated by the NADPH oxidase, linked to GPVI via TRAF4.

OBJECTIVES

The aim of this study was to evaluate the role of early signaling events in ROS generation following engagement of either GPVI/FcRγ or a second immunoreceptor tyrosine-based activation motif (ITAM)-containing receptor on platelets, FcγRIIa.

METHODS AND RESULTS

Using an H(2) DCF-DA-based flow cytometric assay to measure intracellular ROS, we show that treatment of platelets with either the GPVI agonists, collagen-related peptide (CRP) or convulxin (Cvx), or the FcγRIIa agonist 14A2, increased intraplatelet ROS; other platelet agonists such as ADP and TRAP did not. Basal ROS in platelet-rich plasma from 14 healthy donors displayed little inter-individual variability. CRP, Cvx or 14A2 induced an initial burst of ROS within 2 min followed by additional ROS reaching a plateau after 15-20 min. The Syk inhibitor BAY61-3606, which blocks ITAM-dependent signaling, had no effect on the initial ROS burst, but completely inhibited the second phase.

CONCLUSIONS

Together, these results show for the first time that ROS generation downstream of GPVI or FcγRIIa consists of two distinct phases: an initial Syk-independent burst followed by additional Syk-dependent generation.

Cadherin 6 has a functional role in platelet aggregation and thrombus formation

OBJECTIVE

Thrombosis occurs at sites of vascular injury when platelets adhere to subendothelial matrix proteins and to each other. Platelets express many surface receptor proteins, the function of several of these remains poorly characterized. Cadherin 6 is expressed on the platelet surface and contains an arginine-glycine-aspartic acid motif, suggesting that it might have a supportive role in thrombus formation. The aim of this study was to characterize the role of cadherin 6 in platelet function.

METHODS AND RESULTS

Platelet aggregation was inhibited by both antibodies and exogenous soluble cadherin 6. Platelet adhesion to immobilized cadherin 6 was inhibited by arginine-glycine-aspartic acid-serine tetrapeptides. Antibodies to α(IIb)β(3) inhibited platelet adhesion to cadherin 6. Because platelet aggregation occurs in fibrinogen and von Willebrand factor double-deficient mice, we investigated whether cadherin 6 is an alternative ligand for the integrin α(IIb)β(3). Platelet aggregation in fibrinogen and von Willebrand factor double-deficient mice was significantly inhibited by an antibody to cadherin 6. In flow-based assays, inhibition of cadherin 6 caused a marked reduction in thrombus formation in both human and mouse blood.

CONCLUSIONS

This study demonstrates the role of cadherin 6 as a novel ligand for α(IIb)β(3) and highlights its function in thrombus formation.

Mental health services for homeless: patient profile and factors associated with suicide and homicide

This study aimed to establish a profile of users of the mental health service for homeless in Cork, comparing this group with those attending a General Adult Service. The homeless group were significantly more likely to be male (89% v. 46%o), unemployed (96% v. 68%), unmarried (98% v. 75%) and under 65 (94% v. 83%). Diagnostically, there was a significantly higher prevalence of schizophrenia (50% v. 34%); personality disorder (37% v. 11%) and substance dependence (74% v. 19%) in the homeless service users. They were more likely to have a history of deliberate self harm (54% v. 21%) and violence (48% v. 10%). Severe mental illness has a high prevalence in the homeless population, with particularly high levels of factors associated with suicide and homicide. Poor compliance and complexity of illness lead to a requirement for significant input from multidisciplinary mental health teams members.

Platelet adhesion and degranulation induce pro-survival and pro-angiogenic signalling in ovarian cancer cells

Thrombosis is common in ovarian cancer. However, the interaction of platelets with ovarian cancer cells has not been critically examined. To address this, we investigated platelet interactions in a range of ovarian cancer cell lines with different metastatic potentials [HIO-80, 59M, SK-OV-3, A2780, A2780cis]. Platelets adhered to ovarian cancer cells with the most significant adhesion to the 59M cell line. Ovarian cancer cells induced platelet activation [P-selectin expression] in a dose dependent manner, with the most significant activation seen in response to the 59M cell line. The platelet antagonists [cangrelor, MRS2179, and apyrase] inhibited 59M cell induced activation suggesting a P2Y12 and P2Y1 receptor mediated mechanism of platelet activation dependent on the release of ADP by 59M cells. A2780 and 59M cells potentiated PAR-1, PAR-4, and TxA2 receptor mediated platelet activation, but had no effect on ADP, epinephrine, or collagen induced activation. Analysis of gene expression changes in ovarian cancer cells following treatment with washed platelets or platelet releasate showed a subtle but valid upregulation of anti-apoptotic, anti-autophagy pro-angiogenic, pro-cell cycle and metabolic genes. Thus, ovarian cancer cells with different metastatic potential adhere and activate platelets differentially while both platelets and platelet releasate mediate pro-survival and pro-angiogenic signals in ovarian cancer cells.

Role of sulphuric acid, ammonia and galactic cosmic rays in atmospheric aerosol nucleation

Atmospheric aerosols exert an important influence on climate through their effects on stratiform cloud albedo and lifetime and the invigoration of convective storms. Model calculations suggest that almost half of the global cloud condensation nuclei in the atmospheric boundary layer may originate from the nucleation of aerosols from trace condensable vapours, although the sensitivity of the number of cloud condensation nuclei to changes of nucleation rate may be small. Despite extensive research, fundamental questions remain about the nucleation rate of sulphuric acid particles and the mechanisms responsible, including the roles of galactic cosmic rays and other chemical species such as ammonia. Here we present the first results from the CLOUD experiment at CERN. We find that atmospherically relevant ammonia mixing ratios of 100 parts per trillion by volume, or less, increase the nucleation rate of sulphuric acid particles more than 100-1,000-fold. Time-resolved molecular measurements reveal that nucleation proceeds by a base-stabilization mechanism involving the stepwise accretion of ammonia molecules. Ions increase the nucleation rate by an additional factor of between two and more than ten at ground-level galactic-cosmic-ray intensities, provided that the nucleation rate lies below the limiting ion-pair production rate. We find that ion-induced binary nucleation of H(2)SO(4)-H(2)O can occur in the mid-troposphere but is negligible in the boundary layer. However, even with the large enhancements in rate due to ammonia and ions, atmospheric concentrations of ammonia and sulphuric acid are insufficient to account for observed boundary-layer nucleation.

cDNA amplification by SMART-PCR and suppression subtractive hybridization (SSH)-PCR

The comparison of two RNA populations that differ from the effects of a single-independent variable, such as a drug treatment or a specific genetic defect, can identify differences in the abundance of specific transcripts that vary in a population-dependent manner. There are a variety of methods for identifying differentially expressed genes, including microarray, SAGE, qRT-PCR, and DDGE. This protocol describes a potentially less sensitive yet relatively easy and cost-effective alternative that does not require prior knowledge of the transcriptomes under investigation and is particularly applicable when minimal levels of starting material, RNA, are available. RNA input can often be a limiting factor when analyzing RNA from, for example, rigorously purified blood cells. This protocol describes the use of SMART-PCR to amplify cDNA from sub-microgram levels of RNA. The amplified cDNA populations under comparison are then subjected to suppression subtractive hybridization (SSH-PCR), a technique that couples subtractive hybridization with suppression PCR to selectively amplify fragments of differentially expressed genes. The final products are cDNA populations enriched for significantly over-represented transcripts in either of the two input RNA preparations. These cDNA populations may then be cloned to make subtracted cDNA libraries and/or used as probes to screen subtracted cDNA, global cDNA, or genomic DNA libraries.

Bioinformatic discovery of novel bioactive peptides

Short synthetic oligopeptides based on regions of human proteins that encompass functional motifs are versatile reagents for understanding protein signaling and interactions. They can either mimic or inhibit the parent protein's activity and have been used in drug development. Peptide studies typically either derive peptides from a single identified protein or (at the other extreme) screen random combinatorial peptides, often without knowledge of the signaling pathways targeted. Our objective was to determine whether rational bioinformatic design of oligopeptides specifically targeted to potentially signaling-rich juxtamembrane regions could identify modulators of human platelet function. High-throughput in vitro platelet function assays of palmitylated cell-permeable oligopeptides corresponding to these regions identified many agonists and antagonists of platelet function. Many bioactive peptides were from adhesion molecules, including a specific CD226-derived inhibitor of inside-out platelet signaling. Systematic screens of this nature are highly efficient tools for discovering short signaling motifs in molecular signaling pathways.

Monitoring modulators of platelet aggregation in a microtiter plate assay

Platelets play a central role in maintaining biological hemostasis. Inappropriate platelet activation is responsible for thrombotic diseases such as myocardial infarction and stroke. Therefore, novel agents that can inhibit platelet activation are necessary. However, assays that monitor platelet aggregation are generally time-consuming and require high volumes of blood and specialized equipment. Therefore, a medium- to high-throughput assay that can monitor platelet aggregation would be considered useful. Such an assay should be sensitive, comparable to the "gold standard" assay of platelet aggregometry, and able to monitor multiple samples simultaneously but with low assay volumes. We have developed such a microtiter assay. It can assay an average of 60 independent treatments per 60 ml blood donation and demonstrates greater sensitivity than the current gold standard assay, namely platelet aggregation in stirring conditions in a platelet aggregometer. The microtiter plate (MTP) assay can detect known inhibitors of platelet function such as indomethacin, aspirin, and ReoPro. It is highly reproducible when using standard doses of agonists such as thrombin receptor-activating peptide (20 microM) and collagen (0.19 mg/ml). Finally, the MTP assay is rapid and sensitive and can detect unknown platelet-modulating agents from a library of compounds.