HLA-DQA1*05 Carriage Associated With Development of Anti-Drug Antibodies to Infliximab and Adalimumab in Patients With Crohn's Disease.

BACKGROUND & AIMS: Anti-tumor necrosis factor (anti-TNF) therapies are the most widely used biologic drugs for treating immune-mediated diseases, but repeated administration can induce the formation of anti-drug antibodies. The ability to identify patients at increased risk for development of anti-drug antibodies would facilitate selection of therapy and use of preventative strategies. METHODS: We performed a genome-wide association study to identify variants associated with time to development of anti-drug antibodies in a discovery cohort of 1240 biologic-naïve patients with Crohn's disease starting infliximab or adalimumab therapy. Immunogenicity was defined as an anti-drug antibody titer ≥10 AU/mL using a drug-tolerant enzyme-linked immunosorbent assay. Significant association signals were confirmed in a replication cohort of 178 patients with inflammatory bowel disease. RESULTS: The HLA-DQA1*05 allele, carried by approximately 40% of Europeans, significantly increased the rate of immunogenicity (hazard ratio [HR], 1.90; 95% confidence interval [CI], 1.60-2.25; P = 5.88 × 10-13). The highest rates of immunogenicity, 92% at 1 year, were observed in patients treated with infliximab monotherapy who carried HLA-DQA1*05; conversely the lowest rates of immunogenicity, 10% at 1 year, were observed in patients treated with adalimumab combination therapy who did not carry HLA-DQA1*05. We confirmed this finding in the replication cohort (HR, 2.00; 95% CI, 1.35-2.98; P = 6.60 × 10-4). This association was consistent for patients treated with adalimumab (HR, 1.89; 95% CI, 1.32-2.70) or infliximab (HR, 1.92; 95% CI, 1.57-2.33), and for patients treated with anti-TNF therapy alone (HR, 1.75; 95% CI, 1.37-2.22) or in combination with an immunomodulator (HR, 2.01; 95% CI, 1.57-2.58). CONCLUSIONS: In an observational study, we found a genome-wide significant association between HLA-DQA1*05 and the development of antibodies against anti-TNF agents. A randomized controlled biomarker trial is required to determine whether pretreatment testing for HLA-DQA1*05 improves patient outcomes by helping physicians select anti-TNF and combination therapies. ClinicalTrials.gov ID: NCT03088449.

JAK1 inhibition and inflammatory bowel disease.

Primary non-response and secondary loss of response remain a significant issue with the currently available treatment options for a significant proportion of patients with inflammatory bowel disease (IBD). There are multiple unmet needs in the IBD treatment algorithm and new treatment options are required. As our understanding of the pathogenesis of IBD evolves, new therapeutic targets are being identified. The JAK-STAT pathway has been extensively studied. Tofacitinib, a JAK1 inhibitor, is now licensed for use in the induction and maintenance of ulcerative colitis and there are a large number of molecules currently under investigation. These new small molecule drugs (SMDs) will challenge current treatment pathways at a time when clinical therapeutic outcomes are rapidly evolving and becoming more ambitious. This is a review of the current JAK1 inhibitors in IBD including the current evidence from clinical trials.

Relativistic jet activity from the tidal disruption of a star by a massive black hole.

Supermassive black holes have powerful gravitational fields with strong gradients that can destroy stars that get too close, producing a bright flare in ultraviolet and X-ray spectral regions from stellar debris that forms an accretion disk around the black hole. The aftermath of this process may have been seen several times over the past two decades in the form of sparsely sampled, slowly fading emission from distant galaxies, but the onset of the stellar disruption event has not hitherto been observed. Here we report observations of a bright X-ray flare from the extragalactic transient Swift J164449.3+573451. This source increased in brightness in the X-ray band by a factor of at least 10,000 since 1990 and by a factor of at least 100 since early 2010. We conclude that we have captured the onset of relativistic jet activity from a supermassive black hole. A companion paper comes to similar conclusions on the basis of radio observations. This event is probably due to the tidal disruption of a star falling into a supermassive black hole, but the detailed behaviour differs from current theoretical models of such events.

Understanding the relative contributions of direct environmental effects and passive genotype-environment correlations in the association between familial risk factors and child disruptive behavior disorders.

BACKGROUND: Previous work reports an association between familial risk factors stemming from parental characteristics and offspring disruptive behavior disorders (DBDs). This association may reflect (a) the direct effects of familial environment and (b) a passive gene-environment correlation (r(GE)), wherein the parents provide both the genes and the environment. The current study examined the contributions of direct environmental influences and passive r(GE) by comparing the effects of familial risk factors on child DBDs in genetically related (biological) and non-related (adoptive) families. METHOD: Participants were 402 adoptive and 204 biological families. Familial environment was defined as maternal and paternal maladaptive parenting and antisociality, marital conflict and divorce; offspring DBDs included attention deficit hyperactivity disorder (ADHD), conduct disorder (CD) and oppositional defiant disorder (ODD). Mixed-level regressions estimated the main effects of familial environment, adoption status and the familial environment by adoption status interaction term, which tested for the presence of passive r(GE). RESULTS: There was a main effect of maternal and paternal maladaptive parenting and marital discord on child DBDs, indicating a direct environmental effect. There was no direct environmental effect of maternal or paternal antisociality, but maternal and paternal antisociality had stronger associations with child DBDs in biological families than adoptive families, indicating the presence of a passive r(GE). CONCLUSIONS: Many familial risk factors affected children equally across genetically related and non-related families, providing evidence for direct environmental effects. The relationship of parental antisociality and offspring DBDs was best explained by a passive r(GE), where a general vulnerability toward externalizing psychopathology is passed down by the parents to the children.

An extremely luminous X-ray outburst at the birth of a supernova.

Massive stars end their short lives in spectacular explosions--supernovae--that synthesize new elements and drive galaxy evolution. Historically, supernovae were discovered mainly through their 'delayed' optical light (some days after the burst of neutrinos that marks the actual event), preventing observations in the first moments following the explosion. As a result, the progenitors of some supernovae and the events leading up to their violent demise remain intensely debated. Here we report the serendipitous discovery of a supernova at the time of the explosion, marked by an extremely luminous X-ray outburst. We attribute the outburst to the 'break-out' of the supernova shock wave from the progenitor star, and show that the inferred rate of such events agrees with that of all core-collapse supernovae. We predict that future wide-field X-ray surveys will catch each year hundreds of supernovae in the act of exploding.

Validation of the IBD-Control Questionnaire across different sociodemographic and clinical subgroups: secondary analysis of a nationwide electronic survey.

BACKGROUND: The IBD-Control Questionnaire is a simple, generic measure of patient-perceived disease control used increasingly in clinical practice and research. We aimed to address knowledge gaps in its psychometric performance, to ensure that it can be used with confidence in a variety of contexts. METHODS: We analysed 7341 responses to the IBD Registry COVID-19 survey, sent to 40 911 patients who completed an online self-assessment tool during the pandemic. Questions covered demographics, comorbidities, inflammatory bowel disease [IBD] sub-type, and IBD-Control Questionnaire and symptom scores [CD-PRO2 or UC-PRO2]. Psychometric properties of IBD-Control-8 were tested overall and within subgroups (Crohn's disease [CD], ulcerative colitis [UC] and IBD unclassified; male and female; ≤65 and >65 years; number of co-morbidities; deprivation status). RESULTS: Internal consistency was very strong overall [α: 0.84, ω: 0.89] and for each subgroup [α range: 0.81-0.85; ω: 0.86-0.90]. Construct validity was demonstrated by moderate correlation of each item with global rating [VAS] [rs range: 0.47-0.65], strong correlation between IBD-Control-8 score and VAS [rs = 0.74], moderate-to-strong with PRO2 scores [CD: rs = -0.718; UC: rs = -0.602] and significantly higher IBD-Control-8 scores for PRO2-remission vs PRO2-active, consistent across subgroups. Exploratory and confirmatory factor analyses demonstrated a two-factor model (items loading onto 'Health-related Quality of Life' [HRQoL] or 'Treatment' domains). Extensive tests for factorial invariance confirmed consistency. CONCLUSIONS: IBD-Control-8 is a psychometrically robust scale which can be used across a range of populations. It offers a quick, reliable, and valid method of assessing patient-perceived control. The construct of 'control' includes traditional HRQoL and a novel domain relating to treatment perception.

Real-World Experience of Adalimumab Biosimilar (ABP 501) Use in Patients with Inflammatory Bowel Disease in Europe.

INTRODUCTION: Approval of adalimumab biosimilar ABP 501 (Amgevita®) for inflammatory bowel disease (IBD) was based upon the principle of extrapolation. Real-world experience of ABP 501 utilization in IBD can provide useful information to healthcare providers and patients. METHODS: Data were drawn from the 2020-2021 Adelphi IBD Disease Specific Programme™ conducted in five major European countries. Participating gastroenterologists completed a point-in-time survey to provide patient medical record data, and patients voluntarily completed questionnaires to report health-related quality of life (HRQoL). Descriptive analyses were conducted for "ABP 501 initiators" (received ABP 501 as first advanced therapy) and "RP-ABP 501 switchers" (switched to ABP 501 from reference product [RP; Humira®] as first advanced therapy). RESULTS: This analysis included 239 ABP 501 initiators and 136 RP-ABP 501 switchers. At consultation, initiators had been on ABP 501 treatment for a median of 7.5 months and switchers had received ABP 501 for a median of 7.7 months following the switch from a median of 14.0 months treatment with RP. About 74% of initiators and 89% of switchers were reported by their treating physicians as being in clinical remission. Physicians and patients reported satisfaction with ABP 501 in the range of 92-99% across both groups. Patient self-assessment, including EuroQol visual analogue scale, Short IBD Questionnaire, and Work Productivity and Activity Impairment scores, suggested minimal impairment of HRQoL while on ABP 501. The most common reason for RP to ABP 501 switch was lower healthcare costs. CONCLUSION: Both patients with IBD and treating physicians reported high levels of satisfaction with ABP 501 among initiators and switchers.

ABP 501 (Amgevita^®) is the first approved biosimilar to adalimumab originator (Humira^®), referred to here as the reference product. A biosimilar is a biological product that is highly similar to its reference product in terms of safety, purity, and effectiveness. ABP 501 has been approved for the treatment of certain chronic inflammatory diseases. The approval of ABP 501 for inflammatory disease is based upon the principle of extrapolation, with no clinical trial being conducted in patients with inflammatory bowel disease. Therefore, in this current study, we evaluated the utilization experience of biosimilar ABP 501 in the real-world setting from both physicians' and patients' perspectives. We reported that patients with inflammatory bowel disease who initiated ABP 501 as the first advanced therapy as well as patients who continued therapy on ABP 501 after a switch from the adalimumab reference product both had a high level of satisfaction when using the biosimilar ABP 501. Treating physicians also reported that most of their patients were in clinical remission while on treatment with ABP 501, and patients themselves reported minimal impairment of health-related quality of life.

Healthcare Professional (HCP) and Patient Usability Evaluation and Preferences of Two Auto-injector Devices for Self-Injection of Biosimilars, SB4 and SB5: A Literature Review.

BACKGROUND: Numerous biologic drugs, including etanercept and adalimumab, are administered subcutaneously. This study reviewed the evidence on the usability and preference of self-injection devices of SB4 and SB5 compared with the reference product injectors. METHODS: A systematic search was conducted in PubMed using the search string "(Imraldi OR Hadlima OR SB5 OR Benepali OR Brenzys OR SB4) AND (preference) AND (device)" covering the period from 28 January 2016 (first introduction of SB4) to 31 May 2022. Only articles and abstracts on usability or preference-rating of SB4 and SB5 autoinjectors (AI) written in English were selected. Additional papers identified via manual search supplemented the retrieved papers. RESULTS: A total of nine articles and one conference poster were selected (seven surveys, one observational study, and two phase II studies). Overall, participants of the studies included nurses and rheumatologists, as well as patients who were from three medical specialties where these medicines are most commonly used (rheumatology, gastroenterology, and dermatology). The majority of patients and healthcare professionals rated ease of use and ease of grip as the most important device attributes. SB4/Pen and SB5/Pen were mostly preferred over their prefilled syringes (PFS), Enbrel/Pen, and Humira/Pen. CONCLUSION: The analyzed data on usability and device preference indicate that SB4/Pen and SB5/Pen were preferred over the other reference product autoinjectors, thanks to their button-free design, auditory and visual injection feedback, and overall ease of use. Therefore, they were preferred over the other reference product autoinjectors. Because user-friendly devices can improve treatment adherence, pharmaceutical companies should consider patient convenience when developing medical devices.

Micronutrient Status in Adult Crohn's Disease during Clinical Remission: A Systematic Review.

Adults with Crohn's disease (CD) may be at risk of micronutrient insufficiency in clinical remission through restrictive eating, malabsorption, abnormal losses or inflammation. This systematic review synthesises the literature on micronutrient insufficiency in CD in clinical remission in terms of the prevalence of low circulating micronutrient concentrations and as a comparison against a healthy control (HC). Studies were included if the population was predominantly in remission. A total of 42 studies met the inclusion criteria; 12 were rated as low quality, leaving 30 studies covering 21 micronutrients of medium/high quality that were included in the synthesis. Vitamins D and B12 were the most frequently reported nutrients (8 and 11); there were few eligible studies for the remaining micronutrients. The prevalence studies were consistent in reporting individuals with low Vitamins A, B6, B12 and C, ß-carotene, D, Magnesium, Selenium and Zinc. The comparator studies were inconsistent in finding differences with CD populations; Vitamin D, the most reported nutrient, was only lower than the HC in one-quarter of the studies. Adult CD populations are likely to contain individuals with low levels of one or more micronutrients, with the most substantial evidence for Vitamins D and B12. The studies on other micronutrients are of insufficient number, standardisation and quality to inform practice.

Prediction of Crohn's Disease Stricturing Phenotype Using a NOD2-derived Genomic Biomarker.

BACKGROUND: Crohn's disease (CD) is highly heterogenous and may be complicated by stricturing behavior. Personalized prediction of stricturing will inform management. We aimed to create a stricturing risk stratification model using genomic/clinical data. METHODS: Exome sequencing was performed on CD patients, and phenotype data retrieved. Biallelic variants in NOD2 were identified. NOD2 was converted into a per-patient deleteriousness metric ("GenePy"). Using training data, patients were stratified into risk groups for fibrotic stricturing using NOD2. Findings were validated in a testing data set. Models were modified to include disease location at diagnosis. Cox proportional hazards assessed performance. RESULTS: Six hundred forty-five patients were included (373 children and 272 adults); 48 patients fulfilled criteria for monogenic NOD2-related disease (7.4%), 24 of whom had strictures. NOD2 GenePy scores stratified patients in training data into 2 risk groups. Within testing data, 30 of 161 patients (18.6%) were classified as high-risk based on the NOD2 biomarker, with stricturing in 17 of 30 (56.7%). In the low-risk group, 28 of 131 (21.4%) had stricturing behavior. Cox proportional hazards using the NOD2 risk groups demonstrated a hazard ratio (HR) of 2.092 (P = 2.4 × 10-5), between risk groups. Limiting analysis to patients diagnosed aged < 18-years improved performance (HR-3.164, P = 1 × 10-6). Models were modified to include disease location, such as terminal ileal (TI) disease or not. Inclusion of NOD2 risk groups added significant additional utility to prediction models. High-risk group pediatric patients presenting with TI disease had a HR of 4.89 (P = 2.3 × 10-5) compared with the low-risk group patients without TI disease. CONCLUSIONS: A NOD2 genomic biomarker predicts stricturing risk, with prognostic power improved in pediatric-onset CD. Implementation into a clinical setting can help personalize management.

NOD2 is a well-established risk gene for development of Crohn's disease and stricturing behavior. Here we demonstrate NOD2 can be utilized as a genomic biomarker, stratifying patients into 2 stricturing risk groups. Further refinement using disease location at diagnosis improved risk stratification.

Clinical impact of syndromic molecular point-of-care testing for gastrointestinal pathogens in adults hospitalised with suspected gastroenteritis (GastroPOC): a pragmatic, open-label, randomised controlled trial.

BACKGROUND: Single-occupancy isolation rooms are a finite resource in UK hospitals but are crucial in preventing transmission of infection. Patients with suspected gastroenteritis are nursed in single-occupancy rooms, but delays in laboratory testing lead to non-infectious patients remaining isolated for prolonged periods unnecessarily. Rapid molecular test panels for gastrointestinal pathogens have a run time of around 1 h but their clinical impact is unknown. We aimed to evaluate the clinical impact of syndromic molecular point-of-care testing (mPOCT) for gastrointestinal pathogens in adult patients presenting to hospital with suspected gastroenteritis on single-occupancy room use and a range of other outcome measures. METHODS: In this pragmatic, open-label, randomised controlled trial, we enrolled adults hospitalised with suspected gastroenteritis in a large UK hospital. Patients were randomly allocated (1:1) to receive syndromic mPOCT of stool or rectal samples, or to routine clinical care (control) with laboratory testing. The primary outcome was the duration of time in single-occupancy rooms assessed on a modified intention-to-treat basis. Secondary outcomes included the time to results, time to de-isolation, antibiotic use, and safety outcomes. The study was registered with ISRCTN, ISRCTN88918395, and is complete. FINDINGS: Between March 20, 2017 and March 17, 2020, from 455 patients assessed for eligibility, we enrolled 278 patients, 138 assigned to mPOCT (one withdrawal) and 140 to the control group. The duration (geometric mean) of single-occupancy room isolation was 1·8 days (95% CI 1·5-2·2) in the mPOCT group compared with 2·6 days (2·2-3·0) in the control group (exponentiated coefficient 0·70 [95% CI 0·56 to 0·87]; p=0·0017). The median (IQR) time to results was 1·7 h (1·5-2·0) for mPOCT and 44·7 h (21·2-66·1) for the control group (p<0·0001). Time to de-isolation was 0·6 days (0·3-1·8) in the mPOCT group compared with 2·2 days (1·2-3·2) in the control group, (p<0·0001). Antibiotics were given in 89 (65%) of 137 in the mPOCT group and 66 (47%) of 140 in the control group (p=0·0028). There were no differences between groups in length of hospital stay, or in safety outcomes including mortality, intensive care unit admission, or readmission to hospital. INTERPRETATION: mPOCT for gastrointestinal pathogens in patients with suspected gastroenteritis returned results more rapidly than conventional testing and was associated with a reduction in single-occupancy room use. However, these benefits need to be balanced against a potential increase in antibiotic use. FUNDING: University Hospital Southampton NHS Foundation Trust.

The association of GRB 060218 with a supernova and the evolution of the shock wave.

Although the link between long gamma-ray bursts (GRBs) and supernovae has been established, hitherto there have been no observations of the beginning of a supernova explosion and its intimate link to a GRB. In particular, we do not know how the jet that defines a gamma-ray burst emerges from the star's surface, nor how a GRB progenitor explodes. Here we report observations of the relatively nearby GRB 060218 (ref. 5) and its connection to supernova SN 2006aj (ref. 6). In addition to the classical non-thermal emission, GRB 060218 shows a thermal component in its X-ray spectrum, which cools and shifts into the optical/ultraviolet band as time passes. We interpret these features as arising from the break-out of a shock wave driven by a mildly relativistic shell into the dense wind surrounding the progenitor. We have caught a supernova in the act of exploding, directly observing the shock break-out, which indicates that the GRB progenitor was a Wolf-Rayet star.

Improving outpatient services: the Southampton IBD virtual clinic.

The follow-up of inflammatory bowel disease (IBD) patients is challenging due to the relapsing remitting nature of the diseases, the wide spectrum of severity and complexity as well as the need for monitoring of long-term complications and drug treatments. Conventional outpatient follow-up lacks flexibility for patients and there are competing pressures for clinic time. Alternative follow-up pathways include telephone clinics, self-management programmes or discharging patients. The IBD virtual clinic (VC) is a further option. Patients with an established diagnosis for >2 years, who have been stable for >1 year, do not have primary sclerosing cholangitis and who give their consent, are entered into the VC system. Two months before their annual follow-up is due patients are sent blood test forms and a simple questionnaire with an information sheet. If they meet any of the criteria on the questionnaire, they are asked to contact the IBD specialist nursing team to discuss their situation. The blood test results and the patient's database entry are reviewed to ensure that they are not due surveillance investigations. The patients and their GPs then receive a letter informing them of their management plan. We currently follow-up 20% of the Southampton IBD cohort using the VC. The VC system is an innovative, efficient and patient-responsive method for following up mild to moderate IBD. It is well liked by patients but is dependent on a well-maintained database with good integration of IT systems and requires both clerical and IBD nurse specialist support.

Transitioning from Intravenous to Subcutaneous Vedolizumab in Patients with Inflammatory Bowel Disease [TRAVELESS].

BACKGROUND AND AIMS: Subcutaneous [SC] vedolizumab presents the opportunity for inflammatory bowel disease [IBD] patients to manage their treatment at home. There are currently no data on the process of transitioning patients established on intravenous [IV] to SC vedolizumab as part of routine clinical care. The aim of this programme is to evaluate the clinical and biochemical outcomes of switching a cohort of IBD patients established on IV vedolizumab to SC, at 12 weeks following the transition. METHODS: In all, 178 adult patients were offered the opportunity to transition to SC vedolizumab. Patients who agreed were reviewed prior to switching and at Week 12 [W12] after their first SC dose. Evaluation outcomes included disease activity scores, the IBD-Control Patient-Reported Outcome Measures [PROMs], and faecal calprotectin [FCP]. Reasons for patients declining or accepting transitioning, pharmacokinetics, adverse drug reactions, and risk factors for a poor outcome in SARS-CoV-2 infection were also assessed. RESULTS: A total of 124 patients agreed to transition, of whom 106 patients had been on IV vedolizumab for at least 4 months. There were no statistically significant differences in disease activity scores or IBD-Control PROMs between baseline and W12. A statistically significant increase in FCP was observed [31 µg/g vs. 47 µg/g; p = 0.008], although this was unlikely to be clinically relevant. The most common adverse drug reaction reported was injection site reactions [15%]. Based on this cohort of patients, an expected reduction of £572,000 per annum is likely to be achieved. CONCLUSIONS: Transitioning patients established on IV vedolizumab to SC appears to be safe and effective, with high patient satisfaction and multiple benefits for the health service.

Association of caspase-9 and RUNX3 with inflammatory bowel disease.

Previous linkage studies have identified a region at 1p36 as the susceptibility locus (IBD7) of inflammatory bowel disease (IBD). The objective of this study was to investigate whether polymorphisms of caspase-9 (CASP9) gene and RUNX3 are associated with IBD susceptibility and clinical phenotypes. We studied 555 Crohn's disease (CD) and 651 ulcerative colitis (UC) patients recruited from a single UK center. A total of 964 healthy Caucasian subjects were recruited as controls from general practitioner well person clinics in Oxfordshire. Fourteen single nucleotide polymorphisms (SNPs) of CASP9 and 11 SNPs of RUNX3 were genotyped using matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS) (homogenous MassEXTEND, hME, Sequenom™, Sequenom Inc., San Diego, CA). Linkage disequilibrium (LD) and haplotype association analysis were performed using 2ld and phase v2.0 software. No association of individual SNPs of CASP9 or RUNX3 with UC or CD was identified. The rs1052571 of CASP9 was associated with severe UC [P = 0.0034, odds ratio (OR) = 1.957, 95% confidence interval (CI) = 1.240-3.088]. Significant haplotype associations between CASP9 and IBD were identified, while no association of RUNX3 haplotypes with either UC or CD was found. Our findings suggested that CASP9 gene might be another IBD susceptibility gene.

Nutrition and inflammatory bowel disease: primary or adjuvant therapy.

PURPOSE OF REVIEW: Our understanding of the importance of nutrition in inflammatory bowel disease (IBD) continues to improve. With increasing evidence or cumulative evidence, this article reviews the current data for the role of nutrition in IBD pathogenesis, disease exacerbation and its use in the treatment of IBD in a clinically relevant context. RECENT FINDINGS: Irritable bowel syndrome and obesity prevalence is rising, and is increasingly being recognized in patients with IBD. Exclusive enteral nutrition remains highly relevant because of its efficacy and superior side-effect profile, even when considered against new pharmacological treatments, but requires patient motivation. We are now beginning to understand the importance of micronutrients such as iron and vitamin D, which may not only alter the bowel flora but also have an immune-modulatory effect. More recently, a prebiotic and probiotic combination has been used in a randomized trial for the treatment of IBD. SUMMARY: Macronutrient and micronutrient assessment should be an essential part of nutritional assessment of all patients with IBD. Although research is needed to further our understanding of the immune-modulatory effects of nutrients and supplements, better and more effective therapies combining nutrition and drug treatments like immune-suppressants should be explored.

A link between prompt optical and prompt gamma-ray emission in gamma-ray bursts.

The prompt optical emission that arrives with the gamma-rays from a cosmic gamma-ray burst (GRB) is a signature of the engine powering the burst, the properties of the ultra-relativistic ejecta of the explosion, and the ejecta's interactions with the surroundings. Until now, only GRB 990123 had been detected at optical wavelengths during the burst phase. Its prompt optical emission was variable and uncorrelated with the prompt gamma-ray emission, suggesting that the optical emission was generated by a reverse shock arising from the ejecta's collision with surrounding material. Here we report prompt optical emission from GRB 041219a. It is variable and correlated with the prompt gamma-rays, indicating a common origin for the optical light and the gamma-rays. Within the context of the standard fireball model of GRBs, we attribute this new optical component to internal shocks driven into the burst ejecta by variations of the inner engine. The correlated optical emission is a direct probe of the jet isolated from the medium. The timing of the uncorrelated optical emission is strongly dependent on the nature of the medium.

An infrared flash contemporaneous with the gamma-rays of GRB 041219a.

The explosion that results in a cosmic gamma-ray burst (GRB) is thought to produce emission from two physical processes: the central engine gives rise to the high-energy emission of the burst through internal shocking, and the subsequent interaction of the flow with the external environment produces long-wavelength afterglows. Although observations of afterglows continue to refine our understanding of GRB progenitors and relativistic shocks, gamma-ray observations alone have not yielded a clear picture of the origin of the prompt emission nor details of the central engine. Only one concurrent visible-light transient has been found and it was associated with emission from an external shock. Here we report the discovery of infrared emission contemporaneous with a GRB, beginning 7.2 minutes after the onset of GRB 041219a (ref. 8). We acquired 21 images during the active phase of the burst, yielding early multi-colour observations. Our analysis of the initial infrared pulse suggests an origin consistent with internal shocks.

An origin for short gamma-ray bursts unassociated with current star formation.

Two short (< 2 s) gamma-ray bursts (GRBs) have recently been localized and fading afterglow counterparts detected. The combination of these two results left unclear the nature of the host galaxies of the bursts, because one was a star-forming dwarf, while the other was probably an elliptical galaxy. Here we report the X-ray localization of a short burst (GRB 050724) with unusual gamma-ray and X-ray properties. The X-ray afterglow lies off the centre of an elliptical galaxy at a redshift of z = 0.258 (ref. 5), coincident with the position determined by ground-based optical and radio observations. The low level of star formation typical for elliptical galaxies makes it unlikely that the burst originated in a supernova explosion. A supernova origin was also ruled out for GRB 050709 (refs 3, 31), even though that burst took place in a galaxy with current star formation. The isotropic energy for the short bursts is 2-3 orders of magnitude lower than that for the long bursts. Our results therefore suggest that an alternative source of bursts--the coalescence of binary systems of neutron stars or a neutron star-black hole pair--are the progenitors of short bursts.

A short gamma-ray burst apparently associated with an elliptical galaxy at redshift z = 0.225.

Gamma-ray bursts (GRBs) come in two classes: long (> 2 s), soft-spectrum bursts and short, hard events. Most progress has been made on understanding the long GRBs, which are typically observed at high redshift (z approximately 1) and found in subluminous star-forming host galaxies. They are likely to be produced in core-collapse explosions of massive stars. In contrast, no short GRB had been accurately (< 10'') and rapidly (minutes) located. Here we report the detection of the X-ray afterglow from--and the localization of--the short burst GRB 050509B. Its position on the sky is near a luminous, non-star-forming elliptical galaxy at a redshift of 0.225, which is the location one would expect if the origin of this GRB is through the merger of neutron-star or black-hole binaries. The X-ray afterglow was weak and faded below the detection limit within a few hours; no optical afterglow was detected to stringent limits, explaining the past difficulty in localizing short GRBs.