Arteriovenous fistulae for access to hemodialysis in Chad : feasibility study of a medical civic action program by a French army surgical unit.

INTRODUCTION: Use of chronic intermittent hemodialysis is recent in Chad, where it remains underdeveloped. Vascular access is most commonly by catheter. The objective of our study was to demonstrate the feasibility of arteriovenous fistula (AVF) surgery for hemodialysis during deployments as part of the medical civic action program (MEDCAP). METHODS: We prospectively included all patients admitted for AVF creation at Camp Kossei forward surgical unit in N'Djamena (Chad) between December 2016 and February 2017. Surgery was performed by an experienced vascular surgeon. The data collected included age, sex, cause of kidney failure, type of anesthesia, AVF location, and the duration of the intervention and hospitalization. Patients were examined one month after the procedure to evaluate the functionality, morbidity, and mortality of the AVF. RESULTS: We performed 17 AVF in 3 months. Male to female ratio was 3. High blood pressure was the main cause of chronic kidney failure (55%). All interventions were conducted under locoregional anesthesia. Overall, 35% of fistulae were radiocephalic, 41% brachiocephalic, and 24% brachiobasilic. The mean duration of intervention was 58 minutes and that of hospitalization one day. No deaths occurred. Global morbidity, including non-functioning AVF, was 25%. CONCLUSION: Our study showed that AVF surgery is feasible during deployment, especially in Chad, and meets the needs of the local healthcare facilities. It should be developed and taught to local surgeons.

Management specificities for abdominal, pelvic and vascular penetrating trauma.

Management of patients with penetrating trauma of the abdomen, pelvis and their surrounding compartments as well as vascular injuries depends on the patient's hemodynamic status. Multiple associated lesions are the rule. Their severity is directly correlated with initial bleeding, the risk of secondary sepsis, and lastly to sequelae. In patients who are hemodynamically unstable, the goal of management is to rapidly obtain hemostasis. This mandates initial laparotomy for abdominal wounds, extra-peritoneal packing (EPP) and resuscitative endovascular balloon occlusion of the aorta (REBOA) in the emergency room for pelvic wounds, insertion of temporary vascular shunts (TVS) for proximal limb injuries, ligation for distal vascular injuries, and control of exteriorized extremity bleeding with a tourniquet, compressive or hemostatic dressings for bleeding at the junction or borderline between two compartments, as appropriate. Once hemodynamic stability is achieved, preoperative imaging allow more precise diagnosis, particularly for retroperitoneal or thoraco-abdominal injuries that are difficult to explore surgically. The surgical incisions need to be large, in principle, and enlarged as needed, allowing application of damage control principles.

Specific elements of thoracic wound management.

Damage control for thoracic trauma combines definitive and temporary surgical gestures specifically adapted to the lesions present. A systematic assessment of all injuries to prioritize the specific lesions and their treatments constitutes the first operative stage. Packing and temporary closure have a place in the care of chest injuries.

[Catamenial pneumothorax: easy to see, difficult to manage]. / Pneumothorax cataménial : facile à reconnaître, difficile à traiter.

INTRODUCTION: Catamenial pneumothorax (PNO) is a real clinical occurrence. Several cases are reported in the literature as a spontaneous PNO occurring during the catamenial period among women in their thirties. There is no consensus about management and the recurrence rate is very high whatever the initial treatment. PATIENTS AND METHODS: Among 310 cases of spontaneous PNO operated in our institution in 10 years, we identified five cases of catamenial PNO. A retrospective study of these cases was used to study the initial operating data, including the existence of intrathoracic lesions and the choice of technique of pleurodesis. Patient follow-up was clinically and radiologically. Adjuvant hormonal therapies, recurrence of PNO and treatment modalities have been studied. RESULTS: These five patients of average age 37.6 years (37,38) who had 2.6 (2.3) episodes of right catamenial PNO before hospitalization in surgery department. No patient was smoker. Two of them had a known thoracic or pelvic endometriosis. The initial surgery was video assisted thoracic surgery with a parietal pleurectomy and twice a mesh upon the diaphragm. There were no immediate postoperative complications, and the average length of stay was 6.6 days (5.9). Two patients had adjuvant hormonal therapy. All patients had at least one recurrence and three of them had redo surgery. CONCLUSION: The diagnosis of catamenial PNO must be mentioned in any woman who has a spontaneous pneumothorax right in catamenial period. Endometriosis should be systematically sought. A standardized therapeutic approach to establish the role of surgery and the most appropriate technique as well as the appropriateness and duration of peroperative hormonal therapy remains to be defined.

Cell culture models of transmissible spongiform encephalopathies.

In this review, we describe the generation and use of cell culture models of transmissible spongiform encephalopathies, also known as prion diseases. These models include chronically prion-infected cell lines, as well as cultures expressing variable amounts of wild-type, mutated, or chimeric prion proteins. These cell lines have been widely used to investigate the biology of both the normal and the pathological isoform of the prion protein. They have also contributed to the comprehension of the pathogenic processes occurring in transmissible spongiform encephalopathies and in the development of new therapeutic approaches of these diseases.

An extracellular activator of the Drosophila JAK/STAT pathway is a sex-determination signal element.

Metazoans use diverse and rapidly evolving mechanisms to determine sex. In Drosophila melanogaster an X-chromosome-counting mechanism determines the sex of an individual by regulating the master switch gene, Sex-lethal (Sxl). The X-chromosome dose is communicated to Sxl by a set of X-linked signal elements (XSEs), which activate transcription of Sxl through its 'establishment' promoter, SxlPe. Here we describe a new XSE called sisterlessC (sisC) whose mode of action differs from that of previously characterized XSEs, all of which encode transcription factors that activate SxlPe directly. In contrast, sisC encodes a secreted ligand for the Drosophila Janus kinase (JAK) and 'signal transducer and activator of transcription' (STAT) signal transduction pathway and is allelic to outstretched (os, also called unpaired). We conclude that sisC works indirectly on Sxl through this signalling pathway because mutations in sisC or in the genes encoding Drosophila JAK or STAT reduce expression of SxlPe similarly. The involvement of os in sex determination confirms that secreted ligands can function in cell-autonomous processes. Unlike sex signals for other organisms, sisC has acquired its sex-specific function while maintaining non-sex-specific roles in development, a characteristic that it shares with all other Drosophila XSEs.

Muscle differentiation is antagonized by SOX15, a new member of the SOX protein family.

SOX proteins belong to a multigenic family characterized by a unique DNA binding domain, known as the high mobility group box, that is related to that of the testis determining gene SRY. cDNA sequences for more than 30 SOX genes have been identified, and some are known to have diverse roles in vertebrate differentiation and development. Here, we report the isolation and characterization of mouse Sox15 that was uncovered during a screen for high mobility group box containing transcription factors that are expressed at different levels during skeletal muscle differentiation. Sox15 cDNAs were found at a much higher frequency in myoblasts prior to their differentiation into myotubes. Electrophoretic mobility shift assays indicated that recombinant SOX15 protein was capable of binding to a consensus DNA binding site for SOX proteins. When overexpressed in C2C12 myoblasts, wild type SOX15, but not a C-terminal truncated form or the related protein SOX11, specifically inhibited activation of muscle-specific genes and expression of the basic helix-loop-helix myogenic factors myogenin and MyoD, resulting in a failure of the cells to differentiate into myotubes. These results suggest a specific and repressive role for SOX15, requiring the C-terminal domain, during myogenesis.

Getting more from the two-hybrid system: N-terminal fusions to LexA are efficient and sensitive baits for two-hybrid studies.

Two-hybrid methods detect interactions between two proteins fused at the C-termini of, respectively, a DNA-binding domain and the activation domain of a transcriptional activator. Thus the N-terminus of none of these proteins is available for interaction. We have tested whether a bait protein with a reverted polarity (i.e. N-bait-LexA-C) is suitable for two-hybrid interaction. We show that such constructs give a specific interaction signal, and document two cases where the sensitivity is dramatically increased. Such constructs might lead to the identification of partners missed during classical two-hybrid screens.

Determination of structural requirements for the interaction of Rab6 with RabGDI and Rab geranylgeranyltransferase.

The importance of geranylgeranylation to the interaction of Rab proteins with RabGDI was investigated with a set of Rab6 mutants post-translationally modified by all known C-terminal lipid combinations. Rab6 proteins geranylgeranylated on CXC or CC motifs were found to be significantly better substrates for membrane extraction by RabGDI than either Rab6 proteins geranylgeranylated on CAAL motifs or Rab6 proteins that were farnesylated and palmitoylated. The methylation status of the CXC motif did not significantly affect interaction of wild type Rab6 with RabGDI. Rab6 protein sequences required for RabGDI interaction were then identified. Consistent with the significant homology between Rab-GDI and the Rab escort protein, a subunit of Rab geranylgeranyltransferase (RabGGTase), we show that there is an overlap between Rab6 motifs required for RabGDI binding and RabGGTase processing. The effector domain, loop3/beta 3 and the hypervariable region of Rab6 are all required for RabGDI binding, whereas loop3/beta 3 and the hypervariable region but not the effector domain are required for efficient processing of Rab6 by RabGGTase. Interestingly, however, loop3/beta 3 of Rab6 when introduced into H-Ras is sufficient to allow some in vivo processing of a C-terminal CSC motif.

The effector domain of Rab6, plus a highly hydrophobic C terminus, is required for Golgi apparatus localization.

C-terminal lipid modifications are essential for the interaction of Ras-related proteins with membranes. While all Ras proteins are farnesylated and some palmitoylated, the majority of other Ras-related proteins are geranylgeranylated. One such protein, Rab6, is associated with the Golgi apparatus and has a C-terminal CXC motif that is geranylgeranylated on both cysteines. We show here that farnesylation alone cannot substitute for geranylgeranylation in targeting Rab6 to the Golgi apparatus and that whereas Ras proteins that are farnesylated and palmitoylated are targeted to the plasma membrane, mutant Rab proteins that are both farnesylated and palmitoylated associate with the Golgi apparatus. Using chimeric Ras-Rab proteins, we find that there are sequences in the N-terminal 71 amino acids of Rab6 which are required for Golgi complex localization and show that these sequences comprise or include the effector domain. The C-terminal hypervariable domain is not essential for the Golgi complex targeting of Rab6 but is required to prevent prenylated and palmitoylated Rab6 from localizing to the plasma membrane. Functional analysis of these mutant Rab6 proteins in Saccharomyces cerevisiae shows that wild-type Rab6 and C-terminal mutant Rab6 proteins which localize to the Golgi apparatus in mammalian cells can complement the temperature-sensitive phenotype of ypt6 null mutants. Interestingly, therefore, the C-terminal hypervariable domain of Rab6 is not required for this protein to function in S. cerevisiae.

Post-translational processing and subcellular localization of the Ras-related Rap2 protein.

The ras-related rap2 gene encodes a 21 kDa GTP-binding protein that exhibits many structural similarities with Ras proteins. In particular, it contains a C-terminal CAAX sequence (C, cysteine; A, aliphatic residue; X, any amino acid) which has been shown to direct the post-translational modifications responsible for membrane binding of Ras proteins and nuclear lamins. We have generated cell lines overexpressing the Rap2 protein as well as specific anti-Rap2 antibodies and show that the protein is tightly associated with cellular membranes. Similarly to Ras proteins, the Rap2 protein is synthesized as a soluble and hydrophilic precursor that is processed to the mature hydrophobic membrane-bound form. During its maturation, the Rap2 protein is modified by the attachment of both palmitate and polyisoprenoid groups, as is also the case for H- and N-Ras proteins. Subcellular fractionation by sucrose density centrifugation as well as indirect immunofluorescence experiments show that the Rap2 protein is localized in a low-density compartment that morphologically overlaps with the endoplasmic reticulum, whereas Ras proteins are associated with the plasma membrane. In spite of similar post-translational modifications by palmitoylation and polyisoprenylation, Ras and Rap2 proteins are thus located on distinct subcellular structures.

Effects of the ras-related rap2 protein on cellular proliferation.

Ras oncogenes encode 21-kDa (p21s) GTP binding proteins that are capable of transforming immortalized cells in culture. The ras-related rap1A/Krev-1/smgp21A protein, that exhibits a similar structural organization and contains the same effector domain as ras proteins, antagonizes ras-transformation. In order to investigate whether the closely related (61% identical) rap2 protein had similar capacities, the corresponding cDNA was inserted into constitutive as well as inducible mammalian expression vectors. Neither the wild-type, nor an "activated" mutant carrying a glycine-to-valine substitution at position 12, had any transforming activity. Several independent lines of evidence demonstrate that the rap2 protein exhibits neither growth-promoting nor growth-inhibitory effects, and that its over-expression does not interfere with ras-induced transformation. Thus, in spite of their great similarities, the rap1A/Krev-1/smgp21A and rap2 proteins have distinct physiological properties.

Association of the Ras-antagonistic Rap1/Krev-1 proteins with the Golgi complex.

Ras oncogenes encode 21-kDa GTP-binding proteins that are capable of transforming immortalized cells in culture. Ras proteins are bound to the inner face of the plasma membrane by their C-terminal extremity and are thought to transmit their mitogenic signals via an "effector" domain spanning amino acids 32-42. Two ras-related human genes rap1A and rap1B encode 95% homologous 21-kDa proteins that share with Ras p21 the same effector domain and a similar C-terminal Cys-Ali-Ali-Xaa sequence (where Ali is an aliphatic amino acid; also known as a CAAX sequence). The product of the rap1A gene is identical to that of the Krev-1 cDNA, whose overexpression is capable of reverting the phenotype of Ki-ras-transformed NIH 3T3 cells. Antibodies that do not cross-react with Ras and other Ras-related proteins were obtained by immunizing rabbits with a peptide encompassing residues 121-137 of Rap1 proteins. These antibodies were used to investigate the subcellular localization of Rap1 proteins by indirect immunofluorescence and fractionation techniques. Rap1 proteins were found to be tightly bound to cellular membranes. They did not colocalize with Ras proteins on the plasma membrane and were discovered to be associated with the Golgi complex.

Secretion of interleukin-6 (IL-6) by human monocytes stimulated by muramyl dipeptide and tumour necrosis factor alpha.

We studied IL-6 gene expression in human monocytes stimulated by muramyl dipeptide (MDP), a synthetic immunomodulator derived from mycobacterial cell walls. In control monocytes, two IL-6 transcripts of 3.4 kb and 1.6 kb were easily detected at 2.5 hr of culture and remained stable until 18 hr. In MDP-treated monocytes, three IL-6 RNA species displayed different kinetics of accumulation: a 3.4 kb RNA whose expression already reached its maximum after 2.5 hr exposure to MDP; a 1.6 kb RNA whose expression peaked at 5 hr; and a new RNA species of 1.4 kb which was transiently induced in early time of cell stimulation. TNF-alpha co-operated with MDP to increase IL-6 gene expression and secretion of biological active protein (measured by the hybridoma plasmacytoma growth factor assay). MDP exhibits a broad spectrum of immunomodulation properties such as adjuvant activity, enhancement of macrophage cytotoxicity against tumour and induction of non-specific resistance to intracellular agents. The results reported here suggest that these properties might be linked to the stimulation by MDP of genes coding for key cytokines such as IL-6, TNF and IL-1.

Interferon-beta 2 (BSF-2) mRNA is expressed in human monocytes.

We previously have reported the presence of interferon-beta 2 (IFN-beta 2) mRNA in PHA-stimulated human peripheral blood leukocytes (PBL), as well as in nonstimulated cells, although at a lower level. The IFN-beta 2 cloned from a leukocyte library appeared to be similar to that of the fibroblast IFN-beta 2 gene first described in fibroblasts. To assess the nature of the cell population in which the synthesis of IFN-beta 2 takes place, PBL were fractionated in adherent and nonadherent cells. The antiviral activity of the culture supernatants of adherent cells was characterized as the IFN-beta type by neutralization with polyclonal antibodies raised against purified fibroblast IFN-beta 2. IFN-beta 2 mRNA was observed in enriched monocyte populations and accumulated very rapidly, peaking at 2.5 h. RNA extracted from these cultures encoded in a reticulocyte lysate a protein immunoprecipitated by the anti-IFN-beta 2 antiserum. In addition, IFN-beta 2 secreted in monocyte supernatants also was immunoprecipitated by the specific antiserum and was able to compete with the fibroblast IFN-beta 2, suggesting a strong similarity between the fibroblast and monocyte proteins.

Intracellular human gamma-interferon triggers an antiviral state in transformed murine L cells.

Interaction of human gamma-interferon (IFN-gamma) with a cell-surface receptor is known to be essential for the cell to become resistant to viral infection. Here we demonstrate that IFN-gamma, when present inside the cell, is also capable of inducing a permanent antiviral state. Mouse cells transformed with a truncated human cDNA encoding a mature IFN-gamma protein lacking the signal peptide accumulate high levels of intracellular human IFN-gamma. Not only do these cells acquire a permanent resistance to viral infection, they also exhibit all the biochemical characteristics normally observed after exposure to exogenous IFN. The observed loss of species specificity normally associated with IFN-gamma suggests that this restriction is strictly dependent on the interaction of the molecule with the cell-surface receptor.

Regulation of human gamma-interferon and beta-interferon gene expression in PHA-activated lymphocytes.

Two interferon (IFN) messengers were synthesized in phytohemagglutinin (PHA)-activated lymphocytes: IFN-gamma mRNA and a messenger hybridizing with the IFN-beta 2 probe. They were induced rapidly and declined at a stage when overall RNA was still efficiently transcribed. The IFN-beta 2 mRNA (15S) present in the lymphocytes was slightly different from its fibroblastic counterpart (14S). The kinetics of the accumulation and decay of both lymphocyte IFN messengers differed when assessed by hybridization with the two IFN probes, IFN-gamma mRNA was not detected before mitogenic activation and accumulated for up to 15 h postactivation, while IFN-beta 2 mRNA accumulated even in the absence of PHA activation for up to 5 h, even though the activation raised the IFN-beta 2 mRNA level at 5 h. The disappearance of IFN messengers was prevented when cycloheximide was added 5 h after PHA activation, when the transcription of both messengers had already been turned on, suggesting the presence of the repressor mechanism proposed for IFN-beta 1 and IFN-beta 2 mRNAs in fibroblasts. In the absence of PHA activation, cycloheximide did not induce IFN-beta 2 mRNA transcription as it did in fibroblasts and moreover prevented the accumulation of the messenger observed in the control cells. In contrast to IFN-beta 2 mRNA, cycloheximide treatment of lymphocytes produced a slight accumulation of IFN-gamma mRNA. This accumulation was already detectable 6 h posttreatment and its level remained unchanged for up to 24 h. Addition of actinomycin D, 5 h after PHA activation, did not impair the shut off and accelerated the decay of IFN messengers.