² Deceased during the course of this workHypoxia-inducible factor (HIF), a transcriptional complex conserved from Caenorhabditis elegans to vertebrates, plays a pivotal role in cellular adaptation to low oxygen availability. In normoxia, the HIF-a subunits are targeted for destruction by prolyl hydroxylation, a speci®c modi®cation that provides recognition for the E3 ubiquitin ligase complex containing the von Hippel±Lindau tumour suppressor protein (pVHL). Three HIF prolyl-hydroxylases (PHD1, 2 and 3) were identi®ed recently in mammals and shown to hydroxylate HIF-a subunits. Here we show that speci®c`silencing' of PHD2 with short interfering RNAs is suf®cient to stabilize and activate HIF-1a in normoxia in all the human cells investigated.`Silencing' of PHD1 and PHD3 has no effect on the stability of HIF-1a either in normoxia or upon re-oxygenation of cells brie¯y exposed to hypoxia. We therefore conclude that, in vivo, PHDs have distinct assigned functions, PHD2 being the critical oxygen sensor setting the low steady-state levels of HIF-1a in normoxia. Interestingly, PHD2 is upregulated by hypoxia, providing an HIF-1-dependent auto-regulatory mechanism driven by the oxygen tension. Keywords: angiogenesis/HIF prolyl-hydroxylases/ hypoxia signalling/oxygen sensor/small interfering RNA IntroductionAll organisms possess mechanisms to maintain oxygen homeostasis, which are essential for survival. The hypoxia-inducible factor-1 (HIF-1), conserved during evolution from worms to¯ies to vertebrates, is central to adaptation to low oxygen availability. HIF-1 in turn regulates transcription of many genes involved in cellular and systemic responses to hypoxia, including breathing, vasodilation, anaerobic metabolism, erythropoiesis and angiogenesis. Therefore, hif represents a`master' gene in oxygen homeostasis during embryonic development and postnatal life in both physiological and pathophysiological processes such as tumour growth and metastasis (for a review, see Semenza, 1998).HIF-1 is a heterodimer consisting of one of three a-subunits (HIF-1a, HIF-2a or HIF-3a) and the b-subunit (HIF-1b, also called aryl hydrocarbon nuclear translocator, or ARNT) (Wang et al., 1995;Ema et al., 1997;Tian et al., 1997;Gu et al., 1998). HIF-1b is a constitutive nuclear protein, which also participates in the cellular response to environmental toxins such as aryl hydrocarbons, whereas HIF-a is speci®c to the response to hypoxia (Hoffman et al., 1991). Although oxygen availability regulates multiple steps on HIF-1 transcriptional activation, the dominant control mechanism occurs through oxygen-dependent proteolysis of HIF-a (Huang et al., 1996). The most extensively studied isoform of the a-subunits is the ubiquitous HIF-1a.In normoxia, HIF-1a is constitutively synthesized and sent to destruction by the ubiquitin±proteasome pathway (half-life <5 min) (Salceda and Caro, 1997;Huang et al., 1998;Kallio et al., 1999). This process is mediated by the speci®c binding of pVHL, the product of the von Hippel± Lindau tumour suppressor gene, which...

It was recently demonstrated that embryonic glucagon-producing cells in the pancreas can regenerate and convert into insulin-producing β-like cells through the constitutive/ectopic expression of the Pax4 gene. However, whether α cells in adult mice display the same plasticity is unknown. Similarly, the mechanisms underlying such reprogramming remain unclear. We now demonstrate that the misexpression of Pax4 in glucagon(+) cells age-independently induces their conversion into β-like cells and their glucagon shortage-mediated replacement, resulting in islet hypertrophy and in an unexpected islet neogenesis. Combining several lineage-tracing approaches, we show that, upon Pax4-mediated α-to-β-like cell conversion, pancreatic duct-lining precursor cells are continuously mobilized, re-express the developmental gene Ngn3, and successively adopt a glucagon(+) and a β-like cell identity through a mechanism involving the reawakening of the epithelial-to-mesenchymal transition. Importantly, these processes can repeatedly regenerate the whole β cell mass and thereby reverse several rounds of toxin-induced diabetes, providing perspectives to design therapeutic regenerative strategies.

Hypoxia stabilizes HIF-1a (Hypoxia Inducible Factor-1a), which then triggers the expression of several genes involved in many aspects of cancer progression, including metabolic adaptation, cell survival and angiogenesis. The aim of our study was to evaluate the impact of HIF-1a and CA IX (carbonic anhydrase IX) (one of its target genes) expression on prognosis and treatment outcome of patients with breast cancer. Because of the extreme O 2 -dependent instability of the protein, we first validated HIF-1a staining using xenograft tumours that were subjected to experimental conditions mimicking surgical clamping or sitting at room temperature under normoxic conditions after surgical excision but before fixation. Afterwards, the immunohistochemical staining of HIF-1a and CA IX was evaluated in 132 invasive breast carcinomas with a 10-year follow-up, and correlated to classical clinicopathological parameters and response to adjuvant therapy. No significant correlation was found between tumour size or nodal status and the expression of HIF-1a or CA IX. Statistically significant association was found between HIF-1a or CA IX staining and the grade, hormonal receptors loss and the presence of carcinoma in situ. Overexpression of HIF-1a and CA IX correlates with a poor prognosis in breast cancer. We show that HIF-1a is an independent prognostic factor for distant metastasis-free survival and disease-free survival in multivariate analysis. Furthermore, overexpression of HIF-1a or CA IX correlates with a poor outcome after conventional adjuvant therapy. CA IX is, however, a weaker prognostic and predictive factor than HIF-1a, and its association with HIF1a does not modify the survival curve neither response to therapy, compared to HIF-1a alone. ' 2007 Wiley-Liss, Inc.

Anchoring of the upper flare of the fully covered SEMS with the endoscopic clip is feasible and significantly reduces stent migration.

Total pericystectomy is the surgical method of choice for hepatic hydatid disease. This was performed under videolaparoscopy using the neodymium yttrium-aluminium-garnet (NdYAG) laser, allowing safe control of all vasculobiliary structures entering the pericyst. Case reportA 50-year-old north African man in good general condition was admitted in January 1991. He complained of pain in the right upper quadrant of the abdomen, radiating to the right shoulder. He had neither jaundice nor fever. His eating habits included consumption of raw lamb. Blood tests showed a slight eosinophilia with moderate hyperleucocytosis, but results of liver function tests were normal. Abdominal ultrasonography and computed tomography showed a partially calcified mass of the left hepatic lobe, measuring about 6 cm in diameter. The suspected hydatid nature of this mass was confirmed by specific immunological evaluation, particularly the indirect haemagglutination test and immunoelectrophoresis. As this symptomatic hydatid cyst was favourably located at the anterior edge of the left lobe, surgical resection under videolaparoscopy was undertaken. The operation, consisting of total pericystectomy using the NdYAG laser without opening the cyst, lasted for 160 min. The postoperative course was uneventful. Oral fluids were resumed the next day, and a solid diet was started on the second day after operation. The patient left the hospital on the third day after operation and returned to work 1 week after surgery. Histological examination of the cyst confirmed its hydatid nature. Surgical techniqueThe procedure uses the plane of cleavage close to the pericyst but outside the adjacent normal friable liver tissue, with step-by-step control of all veins and biliary ducts entering the pericyst ( Figure I ).The patient was prepared with legs apart, the surgeon standing between them. The first assistant or camera assistant stood at the right and the second assistant at the left. Two videomonitors were set on both sides of the anaesthetist to give a good view to the surgeon and the assistants. The patient was surgically draped to allow immediate laparotomy if needed. The pneumoperitoneum was insufflated by puncture of the umbilicus and waselectronically controlled at 13 mmHg of constant abdominal pressure. The peroperative monitoring during general anaesthesia included capnography and saturometry. The straight telescope (0") attached to a videocamera (Karl Storz, Tuttlingen, Germany) was inserted through a 10-mm trocar and abdominal exploration was performed first. The hydatid cyst was not visible, hidden under inflammatory adhesions. A search for another intra-abdominal localization of the parasite was negative. Three other trocars were then inserted. One 10-mm trocar inserted 5 cm to the left of the umbilicus was to provide an operating channel for endoscopic surgical instruments, such as the electrical hook cannula, scissors, special cannula for the NdYAG laser fibre, and the Endoclip clip applicator (US Surgical, Norwalk, Connecticut, USA). A 5-mm t...

This study provides strong arguments indicating that IPCH with oxaliplatin is better tolerated than EPIC with mitomycin C and 5-FU, and is twice as efficient in curing residual peritoneal carcinomatosis measuring less than 1 mm.

No abstract

All organisms respond to changes in their environment by activating complex signaling cascades. The "hypoxia-signaling cascade" is activated in response to low oxygen availability and this activation is central to maintaining oxygen homeostasis and hence to survival. By regulating the transcriptional complex hypoxia-inducible factor, hypoxia is associated with several physiopathological processes. Several strategies, based on the targeting of the hypoxia-signaling cascade, have been developed to treat these pathologies. Our review summarize different aspects of the hypoxic pathway.