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E Berger

Publications and source records attributed to E Berger.

At least 19 recordsLinked to original sources
PubMed2006

A novel explosive process is required for the gamma-ray burst GRB 060614.

Over the past decade, our physical understanding of gamma-ray bursts (GRBs) has progressed rapidly, thanks to the discovery and observation of their long-lived afterglow emission. Long-duration (> 2 s) GRBs are associated with the explosive deaths of massive stars ('collapsars', ref. 1), which produce accompanying supernovae; the short-duration (< or = 2 s) GRBs have a different origin, which has been argued to be the merger of two compact objects. Here we report optical observations of GRB 060614 (duration approximately 100 s, ref. 10) that rule out the presence of an associated supernova. This would seem to require a new explosive process: either a massive collapsar that powers a GRB without any associated supernova, or a new type of 'engine', as long-lived as the collapsar but without a massive star. We also show that the properties of the host galaxy (redshift z = 0.125) distinguish it from other long-duration GRB hosts and suggest that an entirely new type of GRB progenitor may be required.

Journal Article↗
PubMed2006

Peptide arrays for the determination of humoral responses induced by active immunization with a monoclonal antibody against EpCAM.

Epithelial cell adhesion molecule (EpCAM) is an attractive target for monoclonal antibody serotherapy because it is over-expressed in approximately 70% of epithelial cancers and their metastatic lesions. IGN101, the immunogenic formulation of the murine monoclonal anti-EpCAM antibody Mab17-1A, has been shown to evoke a strong humoral immune response in both monkey studies and early clinical trials. Notably, there was a reduction in the number of circulating EpCAM-positive tumor cells in the peripheral blood of treated cancer patients. In contrast to earlier publications by other groups, we could not detect an anti-EpCAM immune response upon treatment with Mab17-1A using a conventional but optimized anti-EpCAM ELISA. Therefore, in a novel experimental setup, sera of healthy immunized monkeys, normal human donors and cancer patients immunized with IGN101 were tested for reactivity against a series of overlapping synthetic peptides encompassing the entire sequence of EpCAM prepared by SPOT synthesis on cellular supports. Using this method, sera from normal donors reacted with different peptides compared to sera from healthy monkeys. However, the peptides were clustered in the same regions of EpCAM. Cancer patients generally had a lower reactivity to EpCAM peptides and immunization with IGN101 induced reactivity against a different set of peptides. Antibodies cross-reacting with both the IgG2a framework and with the Mab17-1A idiotype were identified. In summary, our data indicate that some EpCAM peptides may be recognized in a species-specific manner. At least seven EpCAM-derived peptides could be of diagnostic interest (QCQCTSVGAQ, ERVRTYWIII, ALQKEITTRY, TYWIIIELKH, IADVAYYFEK, AYYFEKDVKG, GQTLIYYVDE), while four out of these seven peptides may also possess therapeutic relevance (TYWIIIELKH, ALQKEITTRY, IADVAYYFEK, AYYFEKDVKG).

Amino Acid Sequence↗
PubMed2006

Relativistic ejecta from X-ray flash XRF 060218 and the rate of cosmic explosions.

Over the past decade, long-duration gamma-ray bursts (GRBs)--including the subclass of X-ray flashes (XRFs)--have been revealed to be a rare variety of type Ibc supernova. Although all these events result from the death of massive stars, the electromagnetic luminosities of GRBs and XRFs exceed those of ordinary type Ibc supernovae by many orders of magnitude. The essential physical process that causes a dying star to produce a GRB or XRF, and not just a supernova, is still unknown. Here we report radio and X-ray observations of XRF 060218 (associated with supernova SN 2006aj), the second-nearest GRB identified until now. We show that this event is a hundred times less energetic but ten times more common than cosmological GRBs. Moreover, it is distinguished from ordinary type Ibc supernovae by the presence of 10(48) erg coupled to mildly relativistic ejecta, along with a central engine (an accretion-fed, rapidly rotating compact source) that produces X-rays for weeks after the explosion. This suggests that the production of relativistic ejecta is the key physical distinction between GRBs or XRFs and ordinary supernovae, while the nature of the central engine (black hole or magnetar) may distinguish typical bursts from low-luminosity, spherical events like XRF 060218.

Journal Article↗
PubMed2006

[Role of immunity in the development of progressive multifocal leukoencephalopathy: a report of three patients with type B lymphoma and humoral immunodeficiency and six others with acquired immunodeficiency syndrome].

INTRODUCTION: Progressive multifocal leukoencephalopathy (PML) caused by JC virus (JCV) mostly occurs in different conditions of impaired cellular immunity like acquired immunodeficiency syndrome (AIDS) and rarely when humoral immunity is involved. PML remains unusual although there is a high prevalence of JCV among the population and immunosuppression is not rare because of chemotherapies. METHODS: We present two groups of patients: first, we studied reports of three patients suffering from lymphoma type B who developed a PML, proved by cerebral biopsy. The second group included six HIV-infected patients who developed a PML. No biopsy was made but MRI and the physical examination suggested strong arguments for the diagnosis. RESULTS: In the first group, PML was furthered by humoral immunosuppression (rate of immunoglobulin G under 4 g/l). Average survival was five months. In the second group, HIV-infected patients had a survival range from 2 to 58 months after the first PML symptoms and one of them is still alive. CONCLUSION: Humoral immunosuppression in lymphoma can contribute to the development of PML. PML prognosis is often severe but prolonged survivals were described. So it is necessary to restore a sufficient immunity level. But immunity failure may be insufficient to lead to PML. In the case of lymphomas, the role of malignant lymphocytes in multiplication and mutation of JCV might be an interesting pathophysiological hypothesis.

Adult↗
PubMed2006

[Acute leukaemia in two multiple sclerosis patients treated with mitoxantrone].

INTRODUCTION: Mitoxantrone (Mx) is used as a second-line treatment in multiple sclerosis. Since 1998, eight cases of acute leukemia (AL) have been described. We report two new cases of myeloid AL that occurred during treatment with Mx. OBSERVATIONS: The first case concerned a women who was treated with Mx for 3 months. In spite of a very low total dose (58.32 mg), she developed promyelocytic AL. The second patient died of myeloid AL, 27 months after the last injection of Mx. DISCUSSION: All the reported cases of AL occurring after Mx respond to the criteria of leukemia induced by anti-topoisomerases II. Epidemiological data and those from animal experiments suggest that Mx has direct role in the occurrence of leukemia. CONCLUSION: It must be remembered that even if the risk of Mx-induced leukemia is low, blood cell counts must be closely monitored for at least five years after the last injection of this treatment.

Acute Disease↗
PubMed2005

Evaluation of a sensitive detection method for peptide arrays prepared by SPOT synthesis.

The growing range of applications for peptide arrays prepared by SPOT synthesis confirms that they are a powerful proteomics technique to study numerous aspects of molecular interaction events. The most frequent application for peptide arrays prepared by SPOT synthesis is the identification of linear epitopes that are recognized by antibodies. In the conventional format using secondary antibodies for detection unspecific binding and high background have been observed. This leads to difficulties in evaluation of developed membranes. Especially for application with combinatorial libraries false positive results are to be avoided. To circumvent this issue, we directly labeled compounds of interest with biotin and detected binding by incubation with streptavidin-horseradish peroxidase via chemiluminescence. Optimization of method conditions led to a very sensitive detection technique with no or low number of unspecific spots, which is superior to conventional detection with secondary antibodies. As one consequence, evaluation of competitive assays got more reliable.

Epitope Mapping↗
PubMed2005

The afterglow and elliptical host galaxy of the short gamma-ray burst GRB 050724.

Despite a rich phenomenology, gamma-ray bursts (GRBs) are divided into two classes based on their duration and spectral hardness--the long-soft and the short-hard bursts. The discovery of afterglow emission from long GRBs was a watershed event, pinpointing their origin to star-forming galaxies, and hence the death of massive stars, and indicating an energy release of about 10(51) erg. While theoretical arguments suggest that short GRBs are produced in the coalescence of binary compact objects (neutron stars or black holes), the progenitors, energetics and environments of these events remain elusive despite recent localizations. Here we report the discovery of the first radio afterglow from the short burst GRB 050724, which unambiguously associates it with an elliptical galaxy at a redshift z = 0.257. We show that the burst is powered by the same relativistic fireball mechanism as long GRBs, with the ejecta possibly collimated in jets, but that the total energy release is 10-1,000 times smaller. More importantly, the nature of the host galaxy demonstrates that short GRBs arise from an old (> 1 Gyr) stellar population, strengthening earlier suggestions and providing support for coalescing compact object binaries as the progenitors.

Journal Article↗
PubMed2005

The afterglow of GRB 050709 and the nature of the short-hard gamma-ray bursts.

The final chapter in the long-standing mystery of the gamma-ray bursts (GRBs) centres on the origin of the short-hard class of bursts, which are suspected on theoretical grounds to result from the coalescence of neutron-star or black-hole binary systems. Numerous searches for the afterglows of short-hard bursts have been made, galvanized by the revolution in our understanding of long-duration GRBs that followed the discovery in 1997 of their broadband (X-ray, optical and radio) afterglow emission. Here we present the discovery of the X-ray afterglow of a short-hard burst, GRB 050709, whose accurate position allows us to associate it unambiguously with a star-forming galaxy at redshift z = 0.160, and whose optical lightcurve definitively excludes a supernova association. Together with results from three other recent short-hard bursts, this suggests that short-hard bursts release much less energy than the long-duration GRBs. Models requiring young stellar populations, such as magnetars and collapsars, are ruled out, while coalescing degenerate binaries remain the most promising progenitor candidates.

Journal Article↗
PubMed2005

[Listeria endophthalmitis].

Listeria monocytogenes is a rare cause of endogenous endophthalmitis. During the last 20 years about 30 cases have been published, all of which showed similar clinical features and a profound visual loss mainly owing to delayed diagnosis. This case report is about an otherwise healthy 41-year-old woman whose diagnosis was established 17 days after the onset of symptoms by microbiological cultures. Under sufficient therapy signs of local inflammation disappeared and intraocular pressure decreased. Pars plana vitrectomy was necessary; although post-surgery complications developed, the result was complete recovery of visual acuity.

Adult↗
PubMed2005

Investigation of the effects of physiological and vasodilation-induced autonomic activation on the QTc Interval in healthy male subjects.

AIMS: Drug-induced prolongation of the QTc interval is an important marker for potential proarrhythmic action. Prolongation of the QTc interval results from alteration of the ionic currents that regulate cardiac repolarisation. Such effects may result from direct drug action or alternatively they could also occur indirectly by drug-induced modulation of autonomic tone, which is known to regulate cardiac repolarization. This study examined the effects of physiological and drug-induced autonomic activation on heart rate, QT and QTc intervals. METHODS: We studied 29 healthy male subjects aged 18-30 years. Electrocardiographs were recorded before and during autonomic activation induced by mental activation, standing, exercise and glyceryl trinitrate (GTN) (0.5 mg sublingual)-induced vasodilation in the presence and absence of beta-blockade (atenolol 100 mg daily for 4 days). QT intervals were measured manually by electronic callipers and corrected using the Fridericia formula. RESULTS: Heart rates were significantly increased during mental arithmetic, standing, exercise and GTN and this effect was significantly attenuated by atenolol, except for mental activation. QTc intervals were significantly reduced on standing and exercise and this was significantly attenuated by atenolol during exercise. In contrast, GTN increased QTc intervals (Delta = 5.7 ms, confidence interval +/- 3.2 ms, P < 0.005) and this was not attenuated by atenolol. CONCLUSIONS: Alteration in QTc intervals may result from physiological manoeuvres and vasodilation, interventions known to induce autonomic activation. We suggest that QTc prolongation due to GTN is indirectly mediated and unlikely to carry any proarrhythmic effect. Understanding whether drug-induced QTc prolongation is directly or indirectly mediated may be important to determine any potential proarrhythmic risk.

Adolescent↗
PubMed2004

The sub-energetic gamma-ray burst GRB 031203 as a cosmic analogue to the nearby GRB 980425.

Over the six years since the discovery of the gamma-ray burst GRB 980425, which was associated with the nearby (distance approximately 40 Mpc) supernova 1998bw, astronomers have debated fiercely the nature of this event. Relative to bursts located at cosmological distance (redshift z approximately 1), GRB 980425 was under-luminous in gamma-rays by three orders of magnitude. Radio calorimetry showed that the explosion was sub-energetic by a factor of 10. Here we report observations of the radio and X-ray afterglow of the recent GRB 031203 (refs 5-7), which has a redshift of z = 0.105. We demonstrate that it too is sub-energetic which, when taken together with the low gamma-ray luminosity, suggests that GRB 031203 is the first cosmic analogue to GRB 980425. We find no evidence that this event was a highly collimated explosion viewed off-axis. Like GRB 980425, GRB 031203 appears to be an intrinsically sub-energetic gamma-ray burst. Such sub-energetic events have faint afterglows. We expect intensive follow-up of faint bursts with smooth gamma-ray light curves (common to both GRB 031203 and 980425) to reveal a large population of such events.

Journal Article↗
PubMed2004

Ultrastructural quantification of cell death after injurious compression of bovine calf articular cartilage.

OBJECTIVE: It has been suggested that chondrocyte death by apoptosis may play a role in the pathogenesis of cartilage destruction in osteoarthritis, but the results of in-vivo and in-vitro investigations have been conflicting. To investigate further the cell death in our in-vitro model for traumatic joint injury, we performed a quantitative analysis by electron microscopy (EM) of cell morphology after injurious compression. For comparison, the TUNEL assay was also performed. DESIGN: Articular cartilage explant disks were harvested from newborn calf femoropatellar groove. The disks were subjected to injurious compression (50% strain at a strain rate of 100%/s), incubated for 3 days, and then fixed for quantitative morphological analysis. RESULTS: By TUNEL, the cell apoptosis rate increased from 7 +/- 2% in unloaded controls to 33 +/- 6% after injury (P=0.01; N=8 animals). By EM, the apoptosis rate increased from 5 +/- 1% in unloaded controls to 62 +/- 10% in injured cartilage (P=0.02, N=5 animals). Analysis by EM also identified that of the dead cells in injured disks, 97% were apoptotic by morphology. CONCLUSIONS: These results confirm a significant increase in cell death after injurious compression and suggest that most cell death observed here was by an apoptotic process.

Animals↗
PubMed2004

RNA editing (R/G site) and flip-flop splicing of the AMPA receptor subunit GluR2 in nervous tissue of epilepsy patients.

Editing and alternative splicing of mRNA are posttranscriptional steps probably involved in pathophysiological aspects of epilepsy. The present study analyses the alpha-amino-3-hydroxy-5-methyl-4-isoxazolepropionate (AMPA) receptor subunit GluR2 with respect to the expression of (i) editing at the R/G site and (ii) flip-flop cassettes. Nervous tissue from patients with temporal lobe epilepsy was analysed by RT-PCR followed by restriction enzyme assays. Human autoptic tissue served as control. R/G editing status: the relative amount of edited RNA was significantly increased in the hippocampal tissue, whereas no changes were found in neocortical tissues. Flip-flop expression: no significant alterations were found in relative abundance of spliced variants containing the flip exon. The increased editing at the R/G site in the hippocampal tissue of epilepsy patients may enhance responses to glutamate, resulting in a synapse operating at an increased gain.

Adolescent↗
PubMed2003

A common origin for cosmic explosions inferred from calorimetry of GRB030329.

Past studies have suggested that long-duration gamma-ray bursts have a 'standard' energy of E(gamma) approximately 10(51) erg in the ultra-relativistic ejecta, after correcting for asymmetries in the explosion ('jets'). But a group of sub-energetic bursts, including the peculiar GRB980425 associated with the supernova SN1998bw (E(gamma) approximately 10(48) erg), has recently been identified. Here we report radio observations of GRB030329 that allow us to undertake calorimetry of the explosion. Our data require a two-component explosion: a narrow (5 degrees opening angle) ultra-relativistic component responsible for the gamma-rays and early afterglow, and a wide, mildly relativistic component that produces the radio and optical afterglow more than 1.5 days after the explosion. The total energy release, which is dominated by the wide component, is similar to that of other gamma-ray bursts, but the contribution of the gamma-rays is energetically minor. Given the firm link of GRB030329 with SN2003dh, our result indicates a common origin for cosmic explosions in which, for reasons not yet understood, the energy in the highest-velocity ejecta is extremely variable.

Journal Article↗
PubMed2003

Dynamics of the pi(-)p-->pi(0)pi(0)n reaction for p(pi(-))<750 MeV/c.

Data are presented for the reaction pi(-)p-->pi(0)pi(0)n in the range from threshold to p(pi(-))=750 MeV/c. The systematics of the data and multipole analyses are examined for sensitivity to a f(0)(600) ("sigma") meson. A one-pion-exchange mechanism is found to be very weak, or absent. The reaction appears to become dominated by sequential pi(0) decays through the Delta(1232) resonance as the beam momentum increases, along with substantial interference effects from several competing mechanisms.

Journal Article↗
PubMed2003

The bright optical afterglow of the nearby gamma-ray burst of 29 March 2003.

Past studies of cosmological gamma-ray bursts (GRBs) have been hampered by their extreme distances, resulting in faint afterglows. A nearby GRB could potentially shed much light on the origin of these events, but GRBs with a redshift z <or= 0.2 have been estimated to occur only rarely, about once per decade. Here we report the discovery of the bright optical afterglow emission from the burst of 29 March 2003 (GRB030329; ref. 2). The brightness of the afterglow and the prompt report of its position resulted in extensive follow-up observations at many wavelengths, along with the measurement of the redshift, z = 0.169 (ref. 4). The gamma-ray and afterglow properties of GRB030329 are similar to those of GRBs at cosmological redshifts. Observations have already identified the progenitor as a massive star that exploded as a supernova.

Journal Article↗
PubMed2003

Early optical emission from the gamma-ray burst of 4 October 2002.

Observations of the long-lived emission--or 'afterglow'--of long-duration gamma-ray bursts place them at cosmological distances, but the origin of these energetic explosions remains a mystery. Observations of optical emission contemporaneous with the burst of gamma-rays should provide insight into the details of the explosion, as well as into the structure of the surrounding environment. One bright optical flash was detected during a burst, but other efforts have produced negative results. Here we report the discovery of the optical counterpart of GRB021004 only 193 seconds after the event. The initial decline is unexpectedly slow and requires varying energy content in the gamma-ray burst blastwave over the course of the first hour. Further analysis of the X-ray and optical afterglow suggests additional energy variations over the first few days.

Journal Article↗