Mapping Cell Membrane Organization and Dynamics Using Soft Nanoimprint Lithography.

Membrane shape is a key feature of many cellular processes, including cell differentiation, division, migration, and trafficking. The development of nanostructured surfaces allowing for the in situ manipulation of membranes in living cells is crucial to understand these processes, but this requires complicated and limited-access technologies. Here, we investigate the self-organization of cellular membranes by using a customizable and benchtop method allowing one to engineer 1D SiO2 nanopillar arrays of defined sizes and shapes on high-performance glass compatible with advanced microscopies. As a result of this original combination, we provide a mapping of the morphology-induced modulation of the cell membrane mechanics, dynamics and steady-state organization of key protein complexes implicated in cellular trafficking and signal transduction.

Mass Assays to Quantify Bioactive PtdIns3P and PtdIns5P During Autophagic Responses.

Autophagy is a cellular process whereby cytoplasmic substrates are targeted for degradation in the lysosome via the membrane structures autophagosomes. This process is initiated by specific phosphoinositides, PtdIns3P and PtdIns5P, which play a key role in autophagy by recruiting effectors such as Atg18/WIPI2. Therefore, quantifying those lipids is important to better understand the assembly of the complex autophagic machinery. Herein, we describe in detail methods to quantify PtdIns3P and PtdIns5P by specific mass assays feasible in most laboratories.

Cdc42-dependent F-actin dynamics drive structuration of the demarcation membrane system in megakaryocytes.

UNLABELLED: Essentials Information about the formation of the demarcation membrane system (DMS) is still lacking. We investigated the role of the cytoskeleton in DMS structuration in megakaryocytes. Cdc42/Pak-dependent F-actin remodeling regulates DMS organization for proper megakaryopoiesis. These data highlight the mandatory role of F-actin in platelet biogenesis. SUMMARY: Background Blood platelet biogenesis results from the maturation of megakaryocytes (MKs), which involves the development of a complex demarcation membrane system (DMS). Therefore, MK differentiation is an attractive model for studying membrane remodeling. Objectives We sought to investigate the mechanism of DMS structuration in relationship to the cytoskeleton. Results Using three-dimensional (3D) confocal imaging, we have identified consecutive stages of DMS organization that rely on F-actin dynamics to polarize membranes and nuclei territories. Interestingly, microtubules are not involved in this process. We found that the mechanism underlying F-actin-dependent DMS formation required the activation of the guanosine triphosphate hydrolase Cdc42 and its p21-activated kinase effectors (Pak1/2/3). Förster resonance energy transfer demonstrated that active Cdc42 was associated with endomembrane dynamics throughout terminal maturation. Inhibition of Cdc42 or Pak1/2/3 severely destructured the DMS and blocked proplatelet formation. Even though this process does not require containment within the hematopoietic niche, because DMS structuration was observed upon thrombopoietin-treatment in suspension, integrin outside-in signaling was required for Pak activation and probably resulted from secretion of extracellular matrix by MKs. Conclusions These data indicate a functional link, mandatory for MK differentiation, between actin dynamics, regulated by Cdc42/Pak1/2/3, and DMS maturation.

[Mucorales infection in diabetics]. / Infection à Mucorales chez le patient diabétique.

Naso-orbito-cerebral mucormycosis is a fungal infection reported to occur especially in association with diabetes mellitus. Mucorales germinate in the nasal cavities and then colonize sinuses and the orbit. The diagnosis must be made before meningeal and cerebral impairement. The diagnosis is based on histologic and mucologic examination. Once the diagnosis is confirmed, treatment required high and prolonged dose of intravenous Amphotericine B, otherwise the evolution is fatal.

[Nosocomial Aeromonas hydrophila pneumonia complicating toxic coma]. / Pneumopathie nosocomiale à Aeromonas hydrophila compliquant un coma toxique.

A 24-year-old male homosexual drug addict was admitted in coma and circulatory failure after a 10 g overdose of acebutolol. The usual resuscitative measures were undertaken, together with administration of adrenaline and gastric lavage. Six hours of external cardiac massage and pacing, and high catecholamine doses (36 mg.h-1 of adrenaline and 60 micrograms.kg-1 x min-1 of dobutamine) were required before the circulatory system became again spontaneously efficient. After this acute episode, the patient improved despite acute tubular necrosis. On the third day, bilateral alveolar and interstitial lesions were found on the chest film. Bronchoalveolar lavage and protected distal brushings were carried out. Both Aeromonas hydrophila and Staphylococcus aureus were found in the cultured brushings. Treatment with ceftriaxone, vancomycin and amikacin was introduced. This nosocomial pneumonia was very haemorrhagic, resulting in several bloody casts responsible for several episodes of atelectasis. The patient was definitely extubated on the 18th day, and left the ICU 23 days later without any sequela. His HIV status was negative. Four other infections with the same strain of Aeromonas hydrophila occurred at the same time as this patient's. The common source for this germ was found to be soft water. Several measures have since been undertaken: removal of a centralized water softener, filtration and higher chlorine content in the water circuit, and updating of intensive care protocols for disinfection of equipment.

[Which coronary investigation should be performed in patients with peripheral arterial diseases?]. / Quel bilan coronarien faut-il faire chez un patient présentant une artériopathie périphérique?

In the context of peripheral vascular disease, the clinical history provides a means of evaluating coronary risk. The key features are: age, previous myocardial infarction especially when recent (under 6 months), anginal pain, smoking, diabetes and ventricular arrhythmias. Treadmill testing, often limited by symptoms of claudication, may reveal severe coronary ischemia and thereby the patients at very high risk. Upper limb exercise stress testing gives results similar to standard protocols of non-atherosclerotic patients when correctly performed and a reliable detection and evaluation of coronary lesions. Thallium dipyridamol myocardial scintigraphy is a very useful diagnostic method but requires special radionuclide facilities. This technique demonstrates the site of ischemia. Coronary angiography should be reserved for special cases because the risks of the procedure are always greater in patients with peripheral vascular disease.

[Primary Salmonella brandenburg peritonitis in a non-immunosuppressed female patient]. / Péritonite primitive à Salmonella brandenburg chez une patiente non immuno-déprimée.

Primary peritonitis is rare; the bacteria involved are mainly, by order of frequency: Escherichia coli, Streptococcus pneumoniae, and the other streptococci. Extraintestinal sites of minor salmonellosis are exceptional, although they are constantly progressing, especially since the spread of the HIV-induced epidemic. We report one case of primary Salmonella brandenburg peritonitis, whose mechanism could not be explained, in a non-immunodepressive female patient.

Aspiration pneumonitis prophylaxis in obstetric anaesthesia: comparison of effervescent cimetidine-sodium citrate mixture and sodium citrate.

One hundred and forty-seven patients undergoing elective or emergency Caesarean section under general anaesthesia were allocated randomly to three groups: group 1 (n = 28) received no premedication; group 2 (n = 58) received 0.3-molar sodium citrate 15 ml (sodium citrate 1.16 g); group 3 (n = 61) received effervescent cimetidine-sodium citrate combination (cimetidine 400 mg with sodium citrate 0.9 g) after entering the operating room. Gastric pH was measured at tracheal intubation (pH1) and extubation (pH2). Mean pH1 and mean pH2 values in group 1 were, respectively, 2.25 (SD 1.35) and 2.83 (1.64). Mean pH1 and pH2 values in group 2 were, respectively, 4.38 (1.44) and 4.57 (1.51). In group 3 mean pH1 and pH2 values were, respectively, 5.07 (1.13) and 5.37 (1.30). Percentages of patients with pH1 less than or equal to 2.5 in groups 1, 2 and 3 were, respectively, 75, 13.8 and 1.6. Percentages of patients with pH2 less than or equal to 2.5 in groups 1, 2 and 3 were 50, 10.3 and 1.6, respectively.

[Prevention of aspiration pneumonia in obstetrical anesthesia with the effervescent combination of cimetidine and sodium citrate]. / Prévention de la pneumopathie d'inhalation en anesthésie obstétricale par l'association effervescente cimétidine-citrate de sodium.

The effect of an oral effervescent formulation combining 200 mg cimetidine and 1.8 g sodium citrate on gastric pH and volume were studied in patients undergoing caesarean section. Seventy-four patients undergoing elective (group 1) or emergency caesarean section (group 2) were included. Before entering the operating theater (5 to 60 min before intubation), they were given the tablet dissolved in 15 ml of water. Induction and maintenance of anaesthesia were carried out with conventional techniques. The patient's gastric content was aspirated just after endotracheal intubation, and before extubation. its pH and volume were measured at both times. Mean pH was similar in the two groups after intubation (6.07 +/- 1.13 in group 1; 5.52 +/- 1.14 in group 2) and before extubation (6.32 +/- 1.08 vs. 5.85 +/- 1.02 respectively). Gastric pH was therefore greater than 2.5 in all 74 patients at both times. Mean volumes of gastric content after intubation were greater in group 2 (32.7 +/- 23.9 ml vs. 21.6 +/- 15.8 ml; p less than 0.02). However, just before extubation, these were similar (15.0 +/- 15.4 ml in group 1, 20.1 +/- 14.9 ml in group 2). The percentage of patients in the 2 groups with gastric volumes greater than 25 ml at the time of intubation were not significantly different (29.7% vs. 45.9% respectively). No patient was at risk of developing pneumonitis in case of aspiration (gastric content pH less than 2.5 and volume greater than 25 ml), either during endotracheal intubation or extubation.(ABSTRACT TRUNCATED AT 250 WORDS)

[Spontaneous sub-capsular haematoma of the liver compressing the hepatic veins. Angiographic diagnosis (author's transl)]. / Hématome sous-capsulaire spontané du foie comprimant les veines sus-hépatiques. Diagnostic angiographique

Apart from special types encountered in neonates and during pregnancy, spontaneous sub-capsular haematoma (SCH) of the liver is a rare condition which is usually not recognized before operation. The diagnostic value of arteriography is emphasized by this case of SCH in a 29 year old man which presented spontaneously with the appearance of a large mass in the right hypochondrium with fever and pain. Angiographic changes identical to those seen with a traumatic SCH were found and, in this case, were accompanied by a local reversal in intra-hepatic portal flow related to a tumoural Budd-Chiari phenomenon (compression of the hepatic veins by the haematoma). Despite histological study of the liver, no tumoural, vascular, infective or parasitic aetiology could be found to explain this apparently idiopathic spontaneous SCH.