Early detection of subclinical mastitis in lactating dairy cows using cow-level features.

Subclinical mastitis in cows affects their health, well-being, longevity, and performance, leading to reduced productivity and profit. Early prediction of subclinical mastitis can enable dairy farmers to perform interventions to mitigate its effect. The present study investigated how well predictive models built using machine learning techniques can detect subclinical mastitis up to 7 d before its occurrence. The data set used consisted of 1,346,207 milk-day (i.e., a day when milk was collected on both morning and evening) records spanning 9 yr from 2,389 cows producing on 7 Irish research farms. Individual cow composite milk yield and maximum milk flow were available twice daily, whereas milk composition (i.e., fat, lactose, protein) and somatic cell count (SCC) were collected once per week. Other features describing parity, calving dates, predicted transmitting ability for SCC, body weight, and history of subclinical mastitis were also available. The results of the study showed that a gradient boosting machine model trained to predict the onset of subclinical mastitis 7 d before a subclinical case occurs achieved a sensitivity and specificity of 69.45 and 95.64%, respectively. Reduced data collection frequency, where milk composition and SCC were recorded only every 15, 30, 45, and 60 d was simulated by masking data, to reflect the frequency of recording of this data on commercial dairy farms in Ireland. The sensitivity and specificity scores reduced as recording frequency reduced with respective scores of 66.93 and 80.43% when milk composition and SCC were recorded just every 60 d. Results demonstrate that models built on data that could be recorded routinely available on commercial dairy farms, can achieve useful predictive ability of subclinical mastitis even with reduced frequency of milk composition and SCC recording.

Real-world analysis of clinical and economic impact of 21-gene recurrence score (RS) testing in early-stage breast cancer (ESBC) in Ireland.

PURPOSE: Results from TAILOR-X suggest that up to 70% of hormone receptor-positive (HR+) node-negative (N0) ESBC patients (pts) may avoid chemotherapy (CT) with RS ≤ 25. We assess clinical and economic impacts of RS testing on treatment using real-world data. METHODS: From October 2011 to February 2019, a retrospective, cross-sectional observational study was conducted of HR+ N0 ESBC pts who had RS testing in Ireland. Pts were classified low risk (RS ≤ 25) and high risk (RS > 25). Clinical risk was calculated. Data were collected via electronic patient records. Cost data were supplied by the National Healthcare Pricing Regulatory Authority. RESULTS: 963 pts. Mean age is 56 years. Mean tumour size is 1.7 cm. 114 (11.8%), 635 (66%), 211 (22%), 3 (0.2%) pts had G1, G2, G3 and unknown G, respectively. 796 pts (82.8%) low RS, 159 (16.5%) high RS and 8 pts (0.7%) unknown RS. 263 pts (26%) were aged ≤ 50 at diagnosis; 117 (45%) had RS 0-15, 63 (24.5%) 16-20, 39 (15.3%) 21-25 and 40 (15.2%) RS 26-100. 4 pts (1.5%) had unknown RS. Post-RS testing, 602 pts (62.5%) had a change in CT decision; 593 changed to hormone therapy (HT) alone. In total, 262 pts received CT. Of pts receiving CT; 138 (53%) had RS > 25, 124 (47%) had RS ≤ 25. Of pts aged ≤ 50, 153 (58%) had high clinical risk, of whom 28 had RS 16-20. Assay use achieved a 62.5% change in treatment with 73% of pts avoiding CT. This resulted in savings of €4 million in treatment costs. Deducting assay costs, savings of €1.9 million were achieved. CONCLUSION: Over the 8 years of the study, a 62.5% reduction in CT use was achieved with savings of over €1,900,000.

Morphology, adipocyte size, and fatty acid analysis of dairy cattle digital cushions, and the effect of body condition score and age.

The digital cushion is an essential part of maintaining a healthy foot, working to dissipate foot strike and body weight forces and lameness from claw horn disruption lesions. Despite the importance of the digital cushion, little is known about the basic anatomy, adipocyte morphology, and fatty acid composition in relation to age, limb position, and body condition score. In total, 60 claws (from 17 cows) were selected and collected from a herd, ensuring that body condition score data and computed micro-tomography were known for each animal. Digital cushion tissue underwent histological staining combined with stereology, systematic random sampling, and cell morphology analysis, in addition to lipid extraction followed by fatty acid analysis. The results describe digital cushion architecture and adipocyte sizes. Adipocyte size was similar across all 4 claws (distal left lateral and medial and distal right lateral and medial) and across the ages (aged 2-7 yr); however, animals with body condition score of 3.00 or more at slaughter had a significantly increased cell size in comparison to those with a score of less than 2.50. Of 37 fatty acid methyl esters identified, 5 differed between either the body condition score or different age groups. C10:0 capric acid, C14:0 myristic acid, C15:0 pentadecanoic acid, and C20:0 arachidic acid percentages were all lesser in lower body condition score cows, whereas C22:1n-9 erucic acid measurements were lesser in younger cows. Saturated fatty acid, monounsaturated fatty acid, and polyunsaturated fatty acid percentages were not altered in the different claws, ages, or body condition score groups. Triglyceride quantities did not differ for claw position or age but had decreased quantities in lower body condition score animals. Digital cushion anatomy, cellular morphology, and fatty acid composition have been described in general and also in animals with differing ages, body condition scores, and in the differing claws. Understanding fat deposition, mobilization, and composition are essential in not only understanding the roles that the digital cushion plays but also in preventing disorders and maintaining cattle health and welfare.

Medial Temporal Lobe Contributions to Episodic Future Thinking: Scene Construction or Future Projection?

Previous research has shown that the medial temporal lobes (MTL) are more strongly engaged when individuals think about the future than about the present, leading to the suggestion that future projection drives MTL engagement. However, future thinking tasks often involve scene processing, leaving open the alternative possibility that scene-construction demands, rather than future projection, are responsible for the MTL differences observed in prior work. This study explores this alternative account. Using functional magnetic resonance imaging, we directly contrasted MTL activity in 1) high scene-construction and low scene-construction imagination conditions matched in future thinking demands and 2) future-oriented and present-oriented imagination conditions matched in scene-construction demands. Consistent with the alternative account, the MTL was more active for the high versus low scene-construction condition. By contrast, MTL differences were not observed when comparing the future versus present conditions. Moreover, the magnitude of MTL activation was associated with the extent to which participants imagined a scene but was not associated with the extent to which participants thought about the future. These findings help disambiguate which component processes of imagination specifically involve the MTL.

Is atomised intranasal cocaine systemically absorbed during endoscopic sinus surgery?

BACKGROUND: In order to perform endoscopic sinus surgery (ESS) safely and efficiently, preparation of the nasal mucosa with vasoconstrictor agents is crucial to minimise bleeding. There is no single best method, although traditionally cocaine has been the agent of choice. However, there have been concerns over the potential for systemic side effects when applied topically. With this concern in mind, there exists limited contemporary research looking at cocaine absorption in the context of ESS. This study aims to determine the amount and duration of systemic cocaine absorption after intranasal atomised administration of modified Moffett’s solution prior to ESS. METHODOLOGY: Twelve adults undergoing ESS were enrolled. Modified Moffett's solution containing 100 mg cocaine hydrochloride and 1 mg of adrenaline was administered topically 5 minutes prior to surgery. Serum cocaine and the cocaine degradation product, benzoylecgonine, were measured at specific time points up to 12 hrs post administration. RESULTS: Peak plasma cocaine concentration occurred between 60 and 120 minutes post-administration (range 13-31 micrograms/L). The mean peak plasma concentration was 20.35 micrograms/L occurring at 120 minutes post-administration. Benzoylecgonine was detected in 11 subjects at 60 minutes post-administration and in all subjects 12 hours post-administration of cocaine. CONCLUSIONS: This study demonstrates that there are low levels of systemic absorption of cocaine when administered in an atomised modified Moffett’s formulation prior to endoscopic sinus surgery.

Risk of malignancy in resected pancreatic mucinous cystic neoplasms.

BACKGROUND: Pancreatic mucinous cystic neoplasms (MCNs) are rare mucin-producing cystic tumours defined by the presence of ovarian-type stroma. MCNs have a malignant potential and thus surgery is frequently performed. The aim of this cohort study was to define better the criteria for surgical resection in patients with MCN. METHODS: This multicentre retrospective study included all resected MCNs between 2003 and 2015 in participating centres. Lesions without ovarian-type stroma were excluded. Patient characteristics, preoperative findings, histopathology findings and follow-up data were recorded. RESULTS: The study included 211 patients; their median age was 53 (range 18-82) years, and 202 (95·7 per cent) were women. Median preoperative tumour size was 55 (range 12-230) mm. Thirty-four of the 211 (16·1 per cent) were malignant, and high-grade dysplasia (HGD) was found in a further 13 (6·2 per cent). One-third of MCNs in men were associated with invasive cancer, compared with 15·3 per cent in women. Five cases of malignant transformation occurred in MCNs smaller than 4 cm. All cases of malignancy or HGD were associated with symptoms or features of concern on preoperative cross-sectional imaging. In multivariable analysis, raised carbohydrate antigen 19-9 (odds ratio (OR) 10·54, 95 per cent c.i. 2·85 to 218·23; P < 0·001), tumour size (OR 4·23, 3·02 to 11·03; P = 0·001), mural nodules (OR 3·55, 1·31 to 20·55; P = 0·002) and weight loss (OR 3·40, 2·34 to 12·34; P = 0·034) were independent factors predictive of malignant transformation. CONCLUSIONS: Small indeterminate MCNs with no symptoms or features of concern may safely be observed as they have a low risk of malignant transformation.

Does the hippocampus keep track of time?

In the present study, we examined the role of the medial temporal lobe (MTL) in prospective time estimation at short and long timescales using a novel behavioral paradigm adapted from rodent work. Amnesic patients with MTL damage and healthy control participants estimated the duration of nature-based video clips that were either short (≤ 90 s) or long (more than 4 min). Consistent with previous work in rodents, we found that amnesic patients were impaired at making estimations for long, but not for short durations. Critically, these effects were observed in patients who had lesions circumscribed to the hippocampus, suggesting that the pattern observed was not attributable to the involvement of extra-hippocampal structures. That the MTL, and more specifically the hippocampus, is critical for prospective temporal estimation only at long intervals suggests that multiple neurobiological mechanisms support prospective time estimation.

Evolution of Welding-Fume Aerosols with Time and Distance from the Source: A study was conducted on the spatiotemporal variability in welding-fume concentrations for the characterization of first- and second-hand exposure to welding fumes.

Gas metal arc welding fumes were generated from mild-steel plates and measured near the arc (30 cm), representing first-hand exposure of the welder, and farther away from the source (200 cm), representing second-hand exposure of adjacent workers. Measurements were taken during 1-min welding runs and at subsequent 5-min intervals after the welding process was stopped. Number size distributions were measured in real time. Particle mass distributions were measured using a micro-orifice uniform deposition impactor, and total mass concentrations were measured with polytetrafluorothylene filters. Membrane filters were used for collecting morphology samples for electron microscopy. Average mass concentrations measured near the arc were 45 mg/m3 and 9 mg/m3 at the farther distance. The discrepancy in concentrations at the two distances was attributed to the presence of spatter particles, which were observed only in the morphology samples near the source. As fumes aged over time, mass concentrations at the farther distance decreased by 31% (6.2 mg/m3) after 5 min and an additional 13% (5.4 mg/m3) after 10 min. Particle number and mass distributions during active welding were similar at both distances, indicating similar exposure patterns for welders and adjacent workers. Exceptions were recorded for particles smaller than 50 nm and larger than 3 µm, where concentrations were higher near the arc, indicating higher exposures of welders. These results were confirmed by microscopy analysis. As residence time increased, number concentrations decreased dramatically. In terms of particle number concentrations, second-hand exposures to welding fumes during active welding may be as high as first-hand exposures.

Prevalence and distribution of exposure to Schmallenberg virus in Irish cattle during October 2012 to November 2013.

BACKGROUND: Schmallenberg virus (SBV) was first identified in November 2011. It is a novel Orthobunyavirus (family Bunyaviridae) whose main ill effect is congenital malformation of the musculoskeletal and central nervous systems. It is borne by Culicoides spp., and has spread extensively in western Europe. The first case of SBV in Ireland was diagnosed in October 2012. It was anticipated that once the virus emerged in Ireland that there would be wide scale or nationwide spread over the course of the 2013 vector season. The objectives of this study were to determine the seroprevalence and distribution of exposure to Schmallenberg virus in Irish cattle from November 2012 to November 2013. METHODS: Samples of brain for the pathology based surveillance were collected from malformed bovine and ovine foetuses submitted for post mortem examination. These samples were tested for SBV using RT-qPCR. Three serological surveys were carried out on sera submitted for the national brucellosis eradicartion programme. A spatial analysis of both sets of data was carried out. RESULTS: Between October 2012 and 10th May 2013, SBV was confirmed by RT-qPCR in brain tissues from malformed foetuses obtained from 49 cattle herds and 30 sheep flocks in Ireland. In national serosurveys conducted between November 2012 until November 2013 the herd-level and animal-level SBV seroprevalences in cattle were 53 and 36 % respectively for the first survey, 51 and 35 % for the second survey and 53 and 33 % for the third survey. The herd level seroprevalence in counties ranged from 0 to 100 %, with the counties in the south and southeast having the highest seroprevalence (>50 %), the midlands a moderate herd level seroprevalence (10-50 %) while northern and north western counties had a low herd level seroprevalence (0-10 %). There was close spatial agreement between the results of the two different targeted surveillance strategies. CONCLUSIONS: At the end of the 2012 vector season, there was widespread exposure to SBV among herds in southern and south eastern Ireland. During 2013, there was little or no evidence of further outward spread, unlike the situation in several other European countries. Given the lack of evidence for circulation of the virus since 2012, it is likely that the younger age cohort in herds previously exposed to SBV and substantial proportions of animals of all ages on the margins of affected areas are immunologically naïve to SBV, and would be susceptible to infection if the virus were to re-emerge.

A Field Study on the Respiratory Deposition of the Nano-Sized Fraction of Mild and Stainless Steel Welding Fume Metals.

A field study was conducted to estimate the amount of Cr, Mn, and Ni deposited in the respiratory system of 44 welders in two facilities. Each worker wore a nanoparticle respiratory deposition (NRD) sampler during gas metal arc welding (GMAW) of mild and stainless steel and flux-cored arc welding (FCAW) of mild steel. Several welders also wore side-by-side NRD samplers and closed-face filter cassettes for total particulate samples. The NRD sampler estimates the aerosol's nano-fraction deposited in the respiratory system. Mn concentrations for both welding processes ranged 2.8-199 µg/m3; Ni concentrations ranged 10-51 µg/m3; and Cr concentrations ranged 40-105 µg/m3. Cr(VI) concentrations ranged between 0.5-1.3 µg/m3. For the FCAW process the largest concentrations were reported for welders working in pairs. As a consequence this often resulted in workers being exposed to their own welding fumes and to those generated from the welding partner. Overall no correlation was found between air velocity and exposure (R2 = 0.002). The estimated percentage of the nano-fraction of Mn deposited in a mild-steel-welder's respiratory system ranged between 10 and 56%. For stainless steel welding, the NRD samplers collected 59% of the total Mn, 90% of the total Cr, and 64% of the total Ni. These results indicate that most of the Cr and more than half of the Ni and Mn in the fumes were in the fraction smaller than 300 nm.

Update on the management of cholangiocarcinoma.

Cholangiocarcinoma (CC) is a rare cancer arising from the epithelium of the biliary tree, anywhere from the small peripheral hepatic ducts to the distal common bile duct. Classification systems for CC typically group tumours by anatomical location into intrahepatic, hilar or extrahepatic subtypes. Surgical resection or liver transplantation remains the only curative therapy for CC, but up to 80% of patients present with advanced, irresectable disease. Unresectable CC remains resistant to many chemotherapeutic agents, although gemcitabine, particularly in combination with other agents, has been shown to improve overall survival. Ongoing investigation of biological agents has also yielded some promising results. Several novel interventional and endoscopic techniques for the diagnosis and management of non-operable CC have been developed: initial results show improvements in symptoms and progression-free survival, but further randomised studies are required to establish their role in the management of CC.

A novel method for assessing respiratory deposition of welding fume nanoparticles.

Welders are exposed to high concentrations of nanoparticles. Compared to larger particles, nanoparticles have been associated with more toxic effects at the cellular level, including the generation of more reactive oxygen species activity. Current methods for welding-fume aerosol exposures do not differentiate between the nano-fraction and the larger particles. The objectives of this work are to establish a method to estimate the respiratory deposition of the nano-fraction of selected metals in welding fumes and test this method in a laboratory setting. Manganese (Mn), Nickel (Ni), Chromium (Cr), and hexavalent chromium (Cr(VI)) are commonly found in welding fume aerosols and have been linked with severe adverse health outcomes. Inductively coupled plasma mass spectrometry (ICP-MS) and ion chromatography (IC) were evaluated as methods for analyzing the content of Mn, Ni, Cr, and Cr(VI) nanoparticles in welding fumes collected with nanoparticle respiratory deposition (NRD) samplers. NRD samplers collect nanoparticles at deposition efficiencies that closely resemble physiological deposition in the respiratory tract. The limits of detection (LODs) and quantitation (LOQs) for ICP-MS and IC were determined analytically. Mild and stainless steel welding fumes generated with a robotic welder were collected with NRD samplers inside a chamber. LODs (LOQs) for Mn, Ni, Cr, and Cr(VI) were 1.3 µg (4.43 µg), 0.4 µg (1.14 µg), 1.1 µg (3.33 µg), and 0.4 µg (1.42 µg), respectively. Recovery of spiked samples and certified welding fume reference material was greater than 95%. When testing the method, the average percentage of total mass concentrations collected by the NRD samplers was ~30% for Mn, ~50% for Cr, and ~60% for Ni, indicating that a large fraction of the metals may lie in the nanoparticle fraction. This knowledge is critical to the development of toxicological studies aimed at finding links between exposure to welding fume nanoparticles and adverse health effects. Future work will involve the validation of the method in workplace settings. [Supplementary materials are available for this article. Go to the publisher's online edition of Journal of Occupational and Environmental Hygiene for the following free supplemental resource: Digestion, extraction, and analysis procedures for nylon mesh screens.].

Diagnostic findings in sinonasal aspergillosis in dogs in the United Kingdom: 475 cases (2011-2021).

OBJECTIVES: To describe the diagnostic tests used and their comparative performance in dogs diagnosed with sinonasal aspergillosis in the United Kingdom. A secondary objective was to describe the signalment, clinical findings and common clinicopathologic abnormalities in sinonasal aspergillosis. MATERIALS AND METHODS: A multi-centre retrospective survey was performed involving 23 referral centres in the United Kingdom to identify dogs diagnosed with sinonasal aspergillosis from January 2011 to December 2021. Dogs were included if fungal plaques were seen during rhinoscopy or if ancillary testing (via histopathology, culture, cytology, serology or PCR) was positive and other differential diagnoses were excluded. RESULTS: A total of 662 cases were entered into the database across the 23 referral centres. Four hundred and seventy-five cases met the study inclusion criteria. Of these, 419 dogs had fungal plaques and compatible clinical signs. Fungal plaques were not seen in 56 dogs with turbinate destruction that had compatible clinical signs and a positive ancillary test result. Ancillary diagnostics were performed in 312 of 419 (74%) dogs with observed fungal plaques permitting calculation of sensitivity of cytology as 67%, fungal culture 59%, histopathology 47% and PCR 71%. CLINICAL SIGNIFICANCE: The sensitivities of ancillary diagnostics in this study were lower than previously reported challenging the clinical utility of such tests in sinonasal aspergillosis. Treatment and management decisions should be based on a combination of diagnostics including imaging findings, visual inspection, and ancillary testing, rather than ancillary tests alone.

Selecting Processes to Minimize Hexavalent Chromium from Stainless Steel Welding: Eight welding processes/shielding gas combinations were assessed for generation of hexavalent chromium in stainless steel welding fumes.

Eight welding processes/shielding gas combinations were assessed for generation of hexavalent chromium (Cr6+) in stainless steel welding fumes. The processes examined were gas metal arc welding (GMAW) (axial spray, short circuit, and pulsed spray modes), flux cored arc welding (FCAW), and shielded metal arc welding (SMAW). The Cr6+ fractions were measured in the fumes; fume generation rates, Cr6+ generation rates, and Cr6+ generation rates per unit mass of welding wire were determined. A limited controlled comparison study was done in a welding shop including SMAW, FCAW, and three GMAW methods. The processes studied were compared for costs, including relative labor costs. Results indicate the Cr6+ in the fume varied widely, from a low of 2800 to a high of 34,000 ppm. Generation rates of Cr6+ ranged from 69 to 7800 µg/min, and Cr6+ generation rates per unit of wire ranged from 1 to 270 µg/g. The results of field study were similar to the findings in the laboratory. The Cr6+ (ppm) in the fume did not necessarily correlate with the Cr6+ generation rate. Physical properties were similar for the processes, with mass median aerodynamic diameters ranging from 250 to 336 nm, while the FCAW and SMAW fumes were larger (360 and 670 nm, respectively). CONCLUSION: The pulsed axial spray method was the best choice of the processes studied based on minimal fume generation, minimal Cr6+ generation, and cost per weld. This method is usable in any position, has a high metal deposition rate, and is relatively simple to learn and use.

Safety of zoledronic acid and incidence of osteonecrosis of the jaw (ONJ) during adjuvant therapy in a randomised phase III trial (AZURE: BIG 01-04) for women with stage II/III breast cancer.

The AZURE trial is an ongoing phase III, academic, multi-centre, randomised trial designed to evaluate the role of zoledronic acid (ZOL) in the adjuvant therapy of women with stage II/III breast cancer. Here, we report the safety and tolerability profile of ZOL in this setting. Eligible patients received (neo)adjuvant chemotherapy and/or endocrine therapy and were randomised to receive neither additional treatment nor intravenous ZOL 4 mg. ZOL was administered after each chemotherapy cycle to exploit potential sequence-dependent synergy. ZOL was continued for 60 months post-randomisation (six doses in the first 6 months, eight doses in the following 24 months and five doses in the final 30 months). Serious (SAE) and non-serious adverse event (AE) data generated during the first 36 months on study were analysed for the safety population. 3,360 patients were recruited to the AZURE trial. The safety population comprised 3,340 patients (ZOL 1,665; control 1,675). The addition of ZOL to standard treatment did not significantly impact on chemotherapy delivery. SAE were similar in both treatment arms. No significant safety differences were seen apart from the occurrence of osteonecrosis of the jaw (ONJ) in the ZOL group (11 confirmed cases; 0.7%; 95% confidence interval 0.3-1.1%). ZOL in the adjuvant setting is well tolerated, and can be safely administered in addition to adjuvant therapy including chemotherapy. The adverse events were consistent with the known safety profile of ZOL, with a low incidence of ONJ.

Effect of dietary restriction and compensatory growth on performance, carcass characteristics, and metabolic hormone concentrations in Angus and Belgian Blue steers.

Compensatory growth (CG) is the ability of an animal to undergo accelerated growth after a period of restricted feeding. However, there is a dearth of information in relation to the effect of genotype on CG response, thus the objective of this study was to evaluate CG response in two contrasting breed types, namely Aberdeen Angus (AN) and Belgian Blue (BB). Crossbred AN × Holstein-Friesian or BB × Holstein-Friesian steers were assigned to one of two treatment groups in a two (genotypes) × two (diets) factorial design. For 99 days, one group (11 AN and 12 BB) was offered a high energy control diet (H-H) whereas the second group (11 AN and 12 BB) was offered an energy restricted diet (L-H). At the end of the differential feeding period (99 days), both groups of animals were then offered a high energy control diet for a further 200 days. All animals were then slaughtered on day-299 of the study. During feed restriction, L-H had lower DM intake (DMI), had greater feed conversion ratio (FCR) and lower plasma concentrations of insulin, IGF-1, leptin, glucose, urea, betahydroxybutyrate and smaller M. longissimus thoracis or lumborum muscle and fat depths compared to H-H steers. During realimentation, there was no difference in DMI between diets; however, L-H had greater live weight gain compared to H-H steers. Overall, H-H consumed greater quantities on a DM basis, however, had a higher FCR compared to L-H steers. By the end of the realimentation period, there was no difference in plasma metabolite or hormone concentrations, linear body measurements, ultrasonically scanned fat depths, carcass conformation, dressing percentage or fat class between H-H and L-H steers. At slaughter, carcass weights were affected by diet with greater values for H-H compared to L-H steers. Genotype affected measures associated with body composition including pelvic width and both muscle and fat depths (P < 0.05). Overall, L-H had a CG (or recovery) index of 0.52 and did not make up for the loss of gains during the differential feeding period; however, M. longissimus thoracis et lumborum, a tissue of high economic value, recovered completely making it a target of interest for further investigation.

Early growth response-1 is a regulator of DR5-induced apoptosis in colon cancer cells.

BACKGROUND: Tumour necrosis factor-related apoptosis-inducing ligand (TRAIL) induces tumour cell apoptosis by binding to death receptor 4 (DR4) and DR5. DR4 and DR5 activation however can also induce inflammatory and pro-survival signalling. It is not known how these different cellular responses are regulated and what the individual role of DR4 vs DR5 is in these processes. METHODS: DNA microarray study was carried out to identify genes differentially expressed after DR4 and DR5 activation. RT-PCR and western blotting was used to examine the expression of early growth response gene-1 (Egr-1) and the proteins of the TRAIL signalling pathway. The function of Egr-1 was studied by siRNA-mediated knockdown and overexpression of a dominant-negative version of Egr-1. RESULTS: We show that the immediate early gene, Egr-1, regulates TRAIL sensitivity. Egr-1 is constitutively expressed in colon cancer cells and further induced upon activation of DR4 or DR5. Our results also show that DR4 mediates a type II, mitochondrion-dependent apoptotic pathway, whereas DR5 induces a mitochondrion-independent, type I apoptosis in HCT15 colon carcinoma cells. Egr-1 drives c-FLIP expression and the short splice variant of c-FLIP (c-FLIP(S)) specifically inhibits DR5 activation. CONCLUSION: Selective knockdown of c-FLIP(S) sensitises cells to DR5-induced but not DR4-induced apoptosis and Egr-1 exerts an effect as an inhibitor of the DR5-induced apoptotic pathway, possibly by regulating the expression of c-FLIP(S).