All-trans retinoic acid targets gastric cancer stem cells and inhibits patient-derived gastric carcinoma tumor growth.

Gastric carcinoma is the third leading cause of cancer-related death worldwide. This cancer, most of the time metastatic, is essentially treated by surgery associated with conventional chemotherapy, and has a poor prognosis. The existence of cancer stem cells (CSC) expressing CD44 and a high aldehyde dehydrogenase (ALDH) activity has recently been demonstrated in gastric carcinoma and has opened new perspectives to develop targeted therapy. In this study, we evaluated the effects of all-trans-retinoic acid (ATRA) on CSCs in human gastric carcinoma. ATRA effects were evaluated on the proliferation and tumorigenic properties of gastric carcinoma cells from patient-derived tumors and cell lines in conventional 2D cultures, in 3D culture systems (tumorsphere assay) and in mouse xenograft models. ATRA inhibited both tumorspheres initiation and growth in vitro, which was associated with a cell-cycle arrest through the upregulation of cyclin-dependent kinase (CDK) inhibitors and the downregulation of cell-cycle progression activators. More importantly, ATRA downregulated the expression of the CSC markers CD44 and ALDH as well as stemness genes such as Klf4 and Sox2 and induced differentiation of tumorspheres. Finally, 2 weeks of daily ATRA treatment were sufficient to inhibit gastric tumor progression in vivo, which was associated with a decrease in CD44, ALDH1, Ki67 and PCNA expression in the remaining tumor cells. Administration of ATRA appears to be a potent strategy to efficiently inhibit tumor growth and more importantly to target gastric CSCs in both intestinal and diffuse types of gastric carcinoma.

A beat-by-beat, on-line, cardiovascular index, CARDEAN, to assess circulatory responses to surgery: a randomized clinical trial during spine surgery.

Automated assessment of circulatory response to surgical stimuli is unsolved. Would detection of cardiac baroreflex inhibition assess adequacy of intra-operative anti-nociception upon incision, as performed on-line on a beat-by-beat basis by a cardiovascular index, CARDEAN™? 18 ASA I-II patients undergoing spinal disc repair were studied, in a prospective randomized single-blinded trial (observational study). During infusion of propofol to maintain bispectral index between 40 and 60, patients were allocated to receive an effect site target-controlled infusion of remifentanil at Ce = 2 or 4 ng ml(-1). Upon incision and during surgery, circulatory response was assessed using beat-by-beat measurements of minor hypertension and tachycardia to give a cardiovascular index, CARDEAN, scaled between 0 and 100. Upon skin incision, CARDEAN increased in the remifentanil Ce = 2 ng ml(-1) group (n = 7, P < 0.05), while it did not increase in the remifentanil Ce = 4 ng ml(-1) group (n = 7, P = 0.18). During surgery, retrospectively, CARDEAN > 60 was associated with tachycardia and hypertension (P (k) = 0.81 ± 0.10). Changes in CARDEAN appeared linked to adequacy of anti-nociception.

[Normobaric hyperoxia therapy for patients with traumatic brain injury]. / Hyperoxie normobarique chez le patient traumatisé crânien.

Cerebral ischaemia plays a major role in the outcome of brain-injured patients. Because brain oxygenation can be assessed at bedside using intra-parenchymal devices, there has been a growing interest about whether therapeutic hyperoxia could be beneficial for severely head-injured patients. Normobaric hyperoxia increases brain oxygenation and may improve glucose-lactate metabolism in brain regions at risk for ischaemia. However, benefits of normobaric hyperoxia on neurological outcome are not established yet, that hinders the systematic use of therapeutic hyperoxia in head-injured patients. This therapeutic option might be proposed when brain ischemia persists despite the optimization of cerebral blood flow and arterial oxygen blood content.

[Vascular Ehlers-Danlos syndrome: a clinical syndrome to be known by every anaesthesiologist and intensive care physician]. / Syndrome d'Ehlers-Danlos de type vasculaire : une entité à connaître des anesthésistes-réanimateurs.

We report the case of a 29-year-old female who presented with a series of major vascular complications in rapid succession: haemothorax following rupture of a mammary artery aneurysm, pulmonary embolism, anterior myocardial infarction secondary to spontaneous dissection of the left anterior descending artery and rupture of a false aneurysm of the splenic artery. A diagnosis of Ehlers-Danlos syndrome (vascular variant) was considered the most likely in this context. Characterized by an extreme vascular fragility, this rare disease poses important clinical management issues for the anaesthetist and intensive care physician.

Characterization of a SNF1 homologue from the phytopathogenic fungus Sclerotinia sclerotiorum.

In yeast, the SNF1 gene product is essential for the release of catabolic repression. We report the isolation and characterization of an SNF1 homologue from the necrotrophic pathogen Sclerotinia sclerotiorum. Ss snf1 encodes a 765-amino-acid protein in which the catalytic domain has an overall identity with the yeast proteins varying from 55 to 76% while the C-terminal half of Ss SNF1 has a weak homology of about 20% with the yeast sequences. Reverse transcription-polymerase chain reaction showed that its transcripts were weakly and constitutively expressed in planta and in vitro regardless of the nature of the carbon sources and of the presence or absence of glucose. Expression of Ss snf1 in yeast cells allowed the snf1 mutant cells to utilize sucrose, raffinose or glycerol for growth while expression of the Ss snf1 catalytic domain did not restore growth on raffinose or glycerol. Ss SNF1 is structurally homologous to Snf1p, suggesting that the interactions between the kinase and the accessory subunits to activate the enzymatic complex are conserved in fungi.

Purification and characterization of a glucoamylase secreted by the plant pathogen Scierotinia sclerotiorum.

Among the lytic enzymes secreted by the phytopathogen fungus Sclerotinia sclerotiorum, a starch-degrading enzyme has been isolated and characterized. This glycoprotein of 72 kDa is composed of several isoforms ranging from pI 4.8 to 5.4. The enzymatic parameters have been determined. Specificity studies together with the analysis of the reaction products show that it is an alpha-1,4-glucanohydrolase. This result is also corroborated by the analysis of the N-terminal and two inner amino acids sequences that are very similar to fungal glucoamylase genes or enzymes so far sequenced.

Ambient alkaline pH prevents maturation but not synthesis of ASPA, the aspartyl protease from Penicillium roqueforti.

Penicillium roqueforti secretes an aspartyl protease, ASPA, which represents the main extracellular proteolytic activity. Alkaline pH of the medium plays a major role by inhibiting the enzymatic activity and stopping aspA expression in the presence of casein, an inducing protein. However, casein degradation by the mature enzyme produces peptides which can induce aspA expression at acidic and alkaline pH. ASPA synthesized as a proenzyme is processed at an acidic pH but not at an alkaline pH. The data indicate that, in P. roqueforti, alkaline pH has an indirect repressive effect by inhibiting ASPA maturation and the release of inducers. At an acidic pH, the mature enzyme degrades extracellular proteins and peptides are released to induce aspA. In contrast, at an alkaline pH, the proenzyme remains inactive, the inducing substances are consequently not produced and aspA is no longer expressed.

aspS encoding an unusual aspartyl protease from Sclerotinia sclerotiorum is expressed during phytopathogenesis.

The gene aspS encoding an aspartyl protease has been cloned from Sclerotinia sclerotiorum by screening a genomic library with a PCR-amplified fragment of the gene. The open reading frame of 1368 bp interrupted by one intron would encode a preproprotein of 435 amino acids. The catalytic aspartyl residues characteristic of aspartyl proteases are conserved; however, the active-site motif (DSG) in the N-terminal lobe is unusual in that Ser replaced Thr used in the active-site motif (DTG) of the C-terminal lobe and in all other fungal aspartyl proteases. RT-PCR revealed that aspS expression in axenic culture is not subjected to catabolite repression and demonstrated that aspS is expressed from the beginning of infection of sunflower cotyledons.

Mutation of a putative AMPK phosphorylation site abolishes the repressor activity but not the nuclear targeting of the fungal glucose regulator CRE1.

In filamentous ascomycetes, glucose repression is mediated by CRE1, a zinc-finger protein related to Miglp from yeast. Five putative AMPK phosphorylation motifs identified in the glucose repressor from the phytopathogenic fungus Sclerotinia sclerotiorum were mutated in a GFP::CRE1 translational fusion. Complementation experiments in Aspergillus nidulans and fluorescence microscopy analyses showed that mutation of one site (Ser266) abolishes the repressor activity of the fusion protein but not its nuclear targeting, suggesting that an AMPK protein kinase may be involved in the function of the fungal glucose repressor.

Expression and compartmentation of the glucose repressor CRE1 from the phytopathogenic fungus Sclerotinia sclerotiorum.

The glucose repressor from the phytopathogenic fungus Sclerotinia sclerotiorum is encoded by the cre1 gene. Polyclonal antibodies were raised against a fusion protein (gluthathione S-transferase) GST-CRE1 in order to study cre1 expression. Western blot analyses revealed that CRE1 synthesis is regulated by the nature of the extracellular carbon source. High CRE1 levels are induced by glucose and remain stable after transfer into pectin medium, suggesting the existence of post-translational mechanisms which inactivate CRE1 to allow transcription of glucose-repressed genes. Subcellular fractionation demonstrated that CRE1 is localized in the nuclei of glucose grown hyphae and in the cytoplasm when glucose is removed from the culture medium. CRE1 fused to green fluorescent protein (GFP) was introduced into Aspergillus nidulans. Fluorescence microscopy showed the nuclear localization of the GFP-CRE1 fusion protein according to the presence of glucose in the culture medium, suggesting homologous post-translational regulations of glucose repressors in fungi. We propose that filamentous fungi regulate the activity of the glucose repressor by controlling its nuclear translocation.

Expression of a catalytic domain of a Neocallimastix frontalis endoxylanase gene (xyn3) in Kluyveromyces lactis and Penicillium roqueforti.

A cDNA fragment encoding the A catalytic domain of the Neocallimastix frontalis endoxylanase XYN3 was amplified and cloned by the polymerase chain reaction technique. The xyn3A DNA fragment was inserted between the Saccharomyces cerevisiae phosphoglycerate kinase gene promoter and terminator sequences on a multicopy episomal plasmid for Kluyveromyces lactis. The XYN3A domain was successfully expressed in K. lactis and functional endoxylanase was secreted by the yeast cells with the K. lactis killer toxin secretion signal. The XYN3A domain was also expressed in a strain of Penicillium roqueforti as a fusion protein (ShBLE::XYN3A) of the phleomycin-resistance gene product and the endoxylanase. Active endoxylanase was efficiently secreted from the fungal cells with the Trichoderma viride cellobiohydrolase (CBH1) secretion signal and processed by a related KEX2 endoprotease of the secretion pathway. Several differently glycosylated forms of the recombinant enzymes were secreted by the yeast and the filamentous fungus.

Isolation and expression of a nitrogen regulatory gene, nmc, of Penicillium roqueforti.

The nmc gene, encoding a global nitrogen regulator, has been cloned and characterized from Penicillium roqueforti, a fungus used in the dairy industry. The deduced amino acid sequence predicts a protein of 860 amino acids in length whose zinc finger DNA binding domain is at least 94% identical to those of the homologous fungal proteins. Northern blot analysis showed that nmc expression is induced by nitrogen starvation and not repressed by variation of the external pH.

The glucose repressor CRE1 from Sclerotinia sclerotiorum is functionally related to CREA from Aspergillus nidulans but not to the Mig proteins from Saccharomyces cerevisiae.

We isolated the putative glucose repressor gene cre1 from the phytopathogenic fungus Sclerotinia sclerotiorum. cre1 encodes a 429 amino acid protein 59% similar to the carbon catabolite repressor CREA from Aspergillus nidulans. In addition to the overall amino acid sequence relatedness between CRE1 and CREA proteins, cre1 can functionally complement the A. nidulans creAd30 mutation as assessed by repression of the alcohol dehydrogenase I gene expression. The CREI region carrying the two zinc fingers is also very similar to the DNA binding domains of the Saccharomyces cerevisiae glucose repressors Mig1p and Mig2p. Despite the presence in the CRE1 protein of several motifs involved in the regulation of Miglp activity, cre1 cannot complement mig deficiencies in S. cerevisiae. These data suggest that glucose repression pathways may have evolved differently in yeasts and filamentous fungi.

Multiplicity and expression of xylanases in the rumen fungus Neocallimastix frontalis.

The time course production of xylanolytic enzymes by the rumen anaerobic fungus Neocallimastix frontalis was studied during growth on different carbon sources and revealed using isoelectric focusing and immunoblotting. A constant low level of endoxylanase expression was observed in glucose medium. A high level of xylanase activity was detected in methyl glucoside medium corresponding to the induction of new isoforms which were repressed by the presence of glucose. beta-Xylosidases were constitutively produced at a high level and remained mainly associated to the fungal cells. Polyclonal antibodies raised against the endoxylanases XYLI and XYLII revealed that XYLI was secreted to the different culture media showing a characteristic pattern of constitutive expression, while anti-XYLII recognized several polypeptides larger than XYLII indicating the production of multiple antigenically related enzymes during growth on the inducing substrate.

Purification and characterization of two endopolygalacturonases secreted during the early stages of the saprophytic growth of Sclerotinia sclerotiorum.

Two endopolygalacturonases (endo-PGs) secreted at the early stage of cultures of Sclerotinia sclerotiorum grown on polygalacturonate medium, were purified to apparent homogeneity, using ion exchange chromatography. They are glycoproteins of an apparent weight of 42 and 41.5 kDa and a pI of 4.8. The two purified isoforms found in early cultures were not detected in late cultures. Purification of the isoforms secreted at different stages of growth revealed that the increase of polygalacturonase activity during the culture corresponds to a sequential production of enzymes and to the successive replacement of isoforms by new enzymes.

Controls of the expression of aspA, the aspartyl protease gene from Penicillium roqueforti.

The gene (aspA) encoding the extracellular aspartyl protease from Penicillium roqueforti was cloned and characterized. Northern hybridization analyses and beta-casein degradation assays revealed that aspA was strongly induced by casein in the medium and efficiently repressed by ammonia. External alkaline pH overrides casein induction, resulting in aspA repression. Cis-acting motifs known to mediate nitrogen and pH regulation of fungal gene expression are present in the aspA promoter and protein-DNA binding experiments showed that mycelial proteins interact with various regions of the promoter. Due to the efficient environmental controls on aspA expression, the promoter of aspA is an attractive candidate for the development of a controllable gene expression system in P. roqueforti.

Transformation of the oomycete Saprolegnia monoïca to hygromycin-B resistance.

Saprolegnia monoïca was stably transformed to hygromycin resistance using the plasmids pTH210 and pHAM34H containing a bacterial phosphotransferase gene fused to regulatory sequences from genes of another Oomycete. Vectors pBT6, pCM54, used to transform higher fungi, yielded no stable transformants. DNA hybridizations indicated that transformation resulted from a single-copy integration of the transforming vector. Development of non-resistant subcultures from transformed colonies revealed that the transgene could become silent and was not uniformly expressed in the transformants.

Transient expression of the beta-glucuronidase gene after biolistic transformation of the anaerobic fungus Neocallimastix frontalis.

The rumen anaerobic fungus Neocallimastix frontalis was biolistically transformed using plasmids containing the bacterial beta-glucuronidase gene (GUS) fused to the promoter sequences of the enolase gene from N. frontalis. Multiple copies of the plasmids were precipitated onto tungsten particles and delivered into zoosporangia and a mycelial mat by a helium-driven biolistic device. Transformants were detected by histochemical assay for beta-glucuronidase. It was found that the enolase promoter sequences tested were responsible for the transient expression of the beta-glucuronidase gene. This is the first study presenting results on the transformation of an anaerobic fungus.

A mitochondrial-like targeting signal on the hydrogenosomal malic enzyme from the anaerobic fungus Neocallimastix frontalis: support for the hypothesis that hydrogenosomes are modified mitochondria.

The hydrogenosomal malic enzyme (ME) was purified from the anaerobic fungus Neocallimastix frontalis. Using reverse genetics, the corresponding cDNA was isolated and characterized. The deduced amino acid sequence of the ME showed high similarity to ME from metazoa, plants and protists. Putative functional domains for malate and NAD+/NADP+ binding were identified. Phylogenetic analysis of the deduced amino acid sequence of the new ME suggests that it is homologous to reference bacterial and eukaryotic ME. Most interestingly, the cDNA codes for a protein which contains a 27-amino-acid N-terminus which is not present on the purified mature protein. This presequence shares features with known mitochondrial targeting signals, including an enrichment in Ala, Leu, Ser, and Arg, and the presence of an Arg at position-2 relative to amino acid 1 of the mature protein. This is the first report of a mitochondrial-like targeting signal on a hydrogenosomal enzyme from an anaerobic fungus and provides support for the hypothesis that hydrogenosomes in Neocallimastix frontalis might be modified mitochondria.

Molecular characterization of xyn3, a member of the endoxylanase multigene family of the rumen anaerobic fungus Neocallimastix frontalis.

Different cDNAs designated xyn3 and xyn4 were isolated from an expression library of the anaerobic rumen fungus Neocallimastix frontalis. Xyn3 was further characterized and was shown to contain a single open reading frame of 1821 bp coding for a protein, XYN3, of 607 amino acids (Mr 66 000). The predicted primary structure of XYN3 consisted of two large reiterated regions of 223 amino acids with a high degree of identity (88.3%). Each domain of XYN3, XYN3A and XYN3B, showed significant homology with fungal and bacterial xylanases belonging to the endoxylanase family 11. XYN3 and XYN3A were cloned in a bacterial expression plasmid harbouring a 6 His-C terminal tag and the recombinant proteins XYN3 and XYN3A were purified from Escherichia coli. The recombinant proteins had Mr of 66 800 and 34 000 respectively and hydrolysed xylan to xylo-oligosaccharides. Analysis of truncated forms of XYN3 confirmed that the full-length protein contained two catalytic domains displaying similar substrate specificity. Western-blot analysis using antiserum raised against XYN3A showed that the N. frontalis xylanase was not submitted to post-translational maturation. XYN3A antiserum recognized similar polypeptides in the culture medium of two other rumen fungi, Piromyces rhizinflata and Caecomyces communis.