Université libre de Bruxelles

About: Université libre de Bruxelles is a education organization based out in Brussels, Belgium. It is known for research contribution in the topics: Population & Breast cancer. The organization has 24974 authors who have published 56969 publications receiving 2084303 citations. The organization is also known as: ULB.

The apoptosis-necrosis paradox. Apoptogenic proteases activated after mitochondrial permeability transition determine the mode of cell death

Abstract: Mitochondrial alterations including permeability transition (PT) constitute critical events of the apoptotic cascade and are under the control of Bcl-2 related gene products. Here we show that induction of PT is sufficient to activate CPP32-like proteases with DEVDase activity and the associated cleavage of the nuclear DEVDase substrate poly(ADP-ribose) polymerase (PARP). Thus, direct intervention on mitochondria using a ligand of the mitochondrial benzodiazepin receptor or a protonophore causes DEVDase activation. In addition, the DEVDase activation triggered by conventional apoptosis inducers (glucocorticoids or topoisomerase inhibitors) is prevented by inhibitors of PT. The protease inhibitor N-benzyloxycabonyl-Val-Ala-Asp-fluoromethylketone (Z-VAD.fmk) completely prevents the activation of DEVDase and PARP cleavage, as well as the manifestation of nuclear apoptosis (chromatin condensation, DNA fragmentation, hypoploidy). In addition, Z-VAD.fmk delays the manifestation of apoptosis-associated changes in cellular redox potentials (hypergeneration of superoxide anion, oxidation of compounds of the inner mitochondrial membrane, depletion of non-oxidized glutathione), as well as the exposure of phosphatidylserine residues in the outer plasma membrane leaflet. Although Z-VAD.fmk retards cytolysis, it is incapable of preventing disruption of the plasma membrane during protracted cell culture (12-24 h), even in conditions in which it completely blocks nuclear apoptosis (chromatin condensation and DNA fragmentation). Electron microscopic analysis confirms that cells treated with PT inducers alone undergo apoptosis, whereas cells kept in identical conditions in the presence of Z-VAD.fmk die from necrosis. These observations are compatible with the hypothesis that PT would be a rate limiting step in both the apoptotic and the necrotic modes of cell death. In contrast, it would be the availability of apoptogenic proteases that would determine the choice between the two death modalities.

Distinct contribution of stem and progenitor cells to epidermal maintenance

Abstract: The skin interfollicular epidermis (IFE) is the first barrier against the external environment and its maintenance is critical for survival. Two seemingly opposite theories have been proposed to explain IFE homeostasis. One posits that IFE is maintained by long-lived slow-cycling stem cells that give rise to transit-amplifying cell progeny, whereas the other suggests that homeostasis is achieved by a single committed progenitor population that balances stochastic fate. Here we probe the cellular heterogeneity within the IFE using two different inducible Cre recombinase–oestrogen receptor constructs targeting IFE progenitors in mice. Quantitative analysis of clonal fate data and proliferation dynamics demonstrate the existence of two distinct proliferative cell compartments arranged in a hierarchy involving slow-cycling stem cells and committed progenitor cells. After wounding, only stem cells contribute substantially to the repair and long-term regeneration of the tissue, whereas committed progenitor cells make a limited contribution.

CB1 cannabinoid receptor antagonism: a new strategy for the treatment of liver fibrosis.

Abstract: Hepatic fibrosis, the common response associated with chronic liver diseases, ultimately leads to cirrhosis, a major public health problem worldwide. We recently showed that activation of hepatic cannabinoid CB2 receptors limits progression of experimental liver fibrosis. We also found that during the course of chronic hepatitis C, daily cannabis use is an independent predictor of fibrosis progression. Overall, these results suggest that endocannabinoids may drive both CB2-mediated antifibrogenic effects and CB2-independent profibrogenic effects. Here we investigated whether activation of cannabinoid CB1 receptors (encoded by Cnr1) promotes progression of fibrosis. CB1 receptors were highly induced in human cirrhotic samples and in liver fibrogenic cells. Treatment with the CB1 receptor antagonist SR141716A decreased the wound-healing response to acute liver injury and inhibited progression of fibrosis in three models of chronic liver injury. We saw similar changes in Cnr1-/- mice as compared to wild-type mice. Genetic or pharmacological inactivation of CB1 receptors decreased fibrogenesis by lowering hepatic transforming growth factor (TGF)-beta1 and reducing accumulation of fibrogenic cells in the liver after apoptosis and growth inhibition of hepatic myofibroblasts. In conclusion, our study shows that CB1 receptor antagonists hold promise for the treatment of liver fibrosis.

Secondary structure and dosage of soluble and membrane proteins by attenuated total reflection Fourier-transform infrared spectroscopy on hydrated films.

Abstract: Attenuated total reflection Fourier-transform infrared spectroscopy of thin hydrated films of soluble and membrane protein included in a phospholipid bilayer is shown to provide useful information as to the secondary structure of the protein. The analysis of the amide I band of deuterated samples by Fourier self-deconvolution followed by a curve fitting was performed by a new procedure in which all the input parameters are generated by the computer rather than by the investigator. The results of this analysis provide a correct estimation of the alpha-helix and beta-sheet structure content with a standard deviation of 8.6% when X-ray structures are taken as a reference. We also show that the orientation of the different secondary structures resolved by the Fourier self-deconvolution/curve-fitting procedure and of the phospholipid acyl chains can be simultaneously evaluated for membrane proteins reconstituted in a lipid bilayer. Of special interest for reconstitution of membrane proteins, the lipid/protein ratio can be accurately and quickly determined from the infrared spectrum.

Prophylaxis of post-ERCP pancreatitis: European society of gastrointestinal endoscopy (ESGE) guideline - Updated June 2014

Abstract: This Guideline is an official statement of the European Society of Gastrointestinal Endoscopy (ESGE). It addresses the prophylaxis of post-endoscopic retrograde cholangiopancreatography (post-ERCP) pancreatitis. Main recommendations 1 ESGE recommends routine rectal administration of 100 mg of diclofenac or indomethacin immediately before or after ERCP in all patients without contraindication. In addition to this, in the case of high risk for post-ERCP pancreatitis (PEP), the placement of a 5-Fr prophylactic pancreatic stent should be strongly considered. Sublingually administered glyceryl trinitrate or 250 µg somatostatin given in bolus injection might be considered as an option in high risk cases if nonsteroidal anti-inflammatory drugs (NSAIDs) are contraindicated and if prophylactic pancreatic stenting is not possible or successful. 2 ESGE recommends keeping the number of cannulation attempts as low as possible. 3 ESGE suggests restricting the use of a pancreatic guidewire as a backup technique for biliary cannulation to cases with repeated inadvertent cannulation of the pancreatic duct; if this method is used, deep biliary cannulation should be attempted using a guidewire rather than the contrast-assisted method and a prophylactic pancreatic stent should be placed. 4 ESGE suggests that needle-knife fistulotomy should be the preferred precut technique in patients with a bile duct dilated down to the papilla. Conventional precut and transpancreatic sphincterotomy present similar success and complication rates; if conventional precut is selected and pancreatic cannulation is easily obtained, ESGE suggests attempting to place a small-diameter (3-Fr or 5-Fr) pancreatic stent to guide the cut and leaving the pancreatic stent in place at the end of ERCP for a minimum of 12 – 24 hours. 4 ESGE does not recommend endoscopic papillary balloon dilation as an alternative to sphincterotomy in routine ERCP, but it may be advantageous in selected patients; if this technique is used, the duration of dilation should be longer than 1 minute.