Influenza virus surveillance in Argentina during the 2012 season: antigenic characterization, genetic analysis and antiviral susceptibility.

The activity and circulation of influenza viruses in Argentina was studied during 2012 as part of the Argentinean Surveillance for Influenza and other Respiratory Viruses, in the context of Global Influenza Surveillance. The antigenicity and molecular characteristics of haemagglutinins (HA) of circulating influenza A and B viruses were analysed to assess the emergence of virus variants. Susceptibility to oseltamivir and zanamivir was evaluated by enzymatic assay and results were backed-up by sequencing of the neuraminidase (NA) genes. During the 2012 season, influenza virus circulation in Argentina was detected from weeks 24 to 51. The HA sequences of the studied A(H1N1)pdm09 subtype viruses segregated in a different genetic group compared to those identified during the 2009 pandemic, although they were still closely related antigenically to the vaccine virus A/California/07/2009. The HA sequences of the A(H3N2) viruses analysed fell into the A/Victoria/208/2009 clade, genetic group 3C. A mixed circulation of virus variants belonging to B/Victoria and B/Yamagata lineages was detected, with B/Victoria being dominant. All viruses tested were sensitive to oseltamivir and zanamivir except one. This isolate, an A(H1N1)pdm09 virus possessing the substitution NA-N295S, showed highly reduced inhibition by oseltamivir and reduced inhibition by zanamivir. Virological and epidemiological surveillance remains critical for detection of evolving influenza viruses.

Electron localization following attosecond molecular photoionization.

For the past several decades, we have been able to directly probe the motion of atoms that is associated with chemical transformations and which occurs on the femtosecond (10(-15)-s) timescale. However, studying the inner workings of atoms and molecules on the electronic timescale has become possible only with the recent development of isolated attosecond (10(-18)-s) laser pulses. Such pulses have been used to investigate atomic photoexcitation and photoionization and electron dynamics in solids, and in molecules could help explore the prompt charge redistribution and localization that accompany photoexcitation processes. In recent work, the dissociative ionization of H(2) and D(2) was monitored on femtosecond timescales and controlled using few-cycle near-infrared laser pulses. Here we report a molecular attosecond pump-probe experiment based on that work: H(2) and D(2) are dissociatively ionized by a sequence comprising an isolated attosecond ultraviolet pulse and an intense few-cycle infrared pulse, and a localization of the electronic charge distribution within the molecule is measured that depends-with attosecond time resolution-on the delay between the pump and probe pulses. The localization occurs by means of two mechanisms, where the infrared laser influences the photoionization or the dissociation of the molecular ion. In the first case, charge localization arises from quantum mechanical interference involving autoionizing states and the laser-altered wavefunction of the departing electron. In the second case, charge localization arises owing to laser-driven population transfer between different electronic states of the molecular ion. These results establish attosecond pump-probe strategies as a powerful tool for investigating the complex molecular dynamics that result from the coupling between electronic and nuclear motions beyond the usual Born-Oppenheimer approximation.

Monitoring of reversible boronic acid-diol interactions by fluorine NMR spectroscopy in aqueous media.

Recognition and sensing of various biologically relevant species using boronic acid-based chemosensors have become increasingly popular over the last few years. Herein, we describe a new convenient method for monitoring boronic acid-diol interactions in aqueous media based on (19)F NMR spectroscopy with fluorinated boronic acid probes.

Cerebellar abscess caused by Listeria monocytogenes in a liver transplant patient.

Brain abscesses are a rare but serious complication and have been documented in transplant recipients. Aspergillus is by far the most frequent etiology of post-transplant brain abscesses. Bacteria, apart from Nocardia, have a low association with brain abscesses in transplant recipients. We report herein the case of a 52-year-old man who had undergone orthotopic liver transplantation (OLT) for end-stage liver disease and hepatocellular carcinoma secondary to chronic hepatitis, and who developed a cerebellar abscess (CA) from Listeria monocytogenes. Three months after transplantation, he presented with a 1-week history of headache and vomiting. Computed tomography scan of the brain revealed a space-occupying lesion in the right cerebellum, which was further confirmed by magnetic resonance imaging. Emergency surgery was planned because of pressure effect on the surrounding structures. The patient recovered smoothly from the surgery. To our knowledge, no reports of Listeria CA following OLT have been published in the English literature. This case shows that, although extremely rare, L. monocytogenes may cause CA in liver transplant recipients, and clinicians should be aware of this, so that prompt diagnosis and treatment can be instituted before serious brain damage can occur.

Distinct cellular responses induced by saporin and a transferrin-saporin conjugate in two different human glioblastoma cell lines.

Glioblastoma multiforme (GBM) is the most common primary brain tumour in adults, with a median survival of ~12-18 months post-diagnosis. GBM usually recurs within 12 months post-resection, with poor prognosis. Thus, novel therapeutic strategies to target and kill GBM cells are urgently needed. The marked difference of tumour cells with respect to normal brain cells renders glioblastoma a good candidate for selective targeted therapies. Recent experimental strategies focus on over expressed cell surface receptors. Targeted toxins represent a new class of selective molecules composed by a potent protein toxin and a carrier ligand. Targeted toxins approaches against glioblastoma were under investigation in phase I and II clinical trials with several immunotoxins (IT)/ligand toxins such as IL4-Pseudomonas aeruginosa exotoxin A (IL4-PE, NBI-3001), tumour growth factor fused to PE38, a shorter PE variant, (TGF)alpha-TP-38, IL13-PE38, and a transferrin-C diphtheriae toxin mutant (Tf-CRM107). In this work, we studied the effects of the plant ribosome-inactivating saporin and of its chimera transferrin-saporin against two different GBM cell lines. The data obtained here indicate that cell proliferation is affected by the toxin treatments but that different mechanisms are used, directly linked to the presence of an active or inactive p53. A model is proposed for these alternative intracellular pathways.

Glycosilated nucleolin as marker for human gliomas.

Nucleolin is a multifunctional DNA and RNA binding protein involved in regulation of gene transcription, chromatin remodeling, RNA metabolism, and ribosomal RNA synthesis. Nucleolin seems to be over-expressed in highly proliferative cells and is involved in many aspect of gene expression: DNA recombination and replication, RNA transcription by RNA polymerase I and II, rRNA processing, mRNA stabilization, cytokinesis, and apoptosis. Although nucleolin is localized predominantly in the nucleolus, it has also been shown to be localized in a phosphorylated/glycolsilated form on the cell surface of different cells. Numerous articles dealing with surface nucleolin targeting for tumor therapy have been recently published. However, at present, no extensive informations are so far available for the presence of nucleolin in human gliomas. In the present work we investigated on the presence and localization of nucleolin in glioma on glioma specimens at different grade of malignancy and on primary glioma cell cultures derived by surgical resection, trying to correlate the presence of glycosilated membrane nucleolin with the malignancy grade. To this purpose an antibody produced by us against gp273 protein, demonstrated to recognized the glycosilated surface nucleolin, has been used. The results obtained demonstrate that surface nucleolin increase with the malignancy grade thus suggesting that it may constitute a histopathological marker for glioma grading and a possible tool for targeted therapy.

Signal transduction pathways involved in PPARß/δ-induced neuronal differentiation.

Neuroblastomas are pediatric tumors originating from neuroblasts in the developing peripheral nervous system. The neurotrophin brain-derived neurotrophic factor (BDNF) is a key regulator of survival and differentiation of specific neuronal populations in the central and peripheral nervous system. Patients whose neuroblastoma tumors express high levels of BDNF and TrkB have an unfavorable prognosis. We have previously reported on the neuronal differentiating activity of peroxisome proliferator-activated receptors (PPAR)ß/δ natural and synthetic ligands by modulating BDNF/TrkB pathway, suggesting their potential use as new therapeutic strategies for neuroblastoma. The validation of new therapeutic agents implies the understanding of their mechanisms of action. Herein, we report the effects of activated-PPARß/δ on signal transduction pathways known to be involved in neuronal differentiation, such as ERK1,2 and BDNF pathways. The results obtained, using also PPARß/δ silencing, indicating a neuronal differentiating effect PPARß/δ-dependent through BDNF-P75-ERK1,2 pathways, further support a role for PPARß/δ in neuronal differentiation and pointing towards PPARß/δ as a modulator of pathways crucial for neuronal differentiation. These findings open new perspectives in the formulation of potential therapeutic approaches to be used as adjuvant treatment with the standard therapies.

Hypoxia induces peroxisome proliferator-activated receptor α (PPARα) and lipid metabolism peroxisomal enzymes in human glioblastoma cells.

Glioblastoma multiforme (GBM) represents the most severe type of glioma, the most common brain tumor. Their malignancy shows a relationship with an increased proliferation and a poorly organized tumor vascularization, an event that leads to inadequate blood supply, hypoxic areas and at last to the formation of necrotic areas, a feature of glioblastoma. Hypoxic/necrotic tumors are more resistant to chemotherapy and radiation therapies, thus it is crucial to formulate new therapeutic approaches that can render these tumors more sensitive to the action of conventional therapies. It has been demonstrated that under hypoxia, gliomas accumulate lipid droplets and that this event is positively correlated with the degree of malignancy, glioblastoma being the most endowed with lipid droplets. We have previously demonstrated in ex vivo glioma specimens a grade-dependent lipid metabolism perturbation. Here we studied the lipid pathways and the presence of stemness markers in glioma primary cultures, obtained from surgical specimens of patients affected by glioma at different grade of malignancy, GBM primary cultures cultured under both hypoxic and normoxic conditions, as well as normal human astrocytes. The results obtained demonstrate that hypoxia plays a crucial role in regulating the expression of lipid metabolism peroxisomal enzymes, the lipid droplets accumulation as well as the transcription factor PPARα.

Gastrointestinal tuberculosis in renal transplant recipients: case report and review of the literature.

Mycobacterium tuberculosis is an important opportunistic pathogen following renal transplantation and is often associated with adverse outcomes. Gastrointestinal tuberculosis (GITB) is an infrequent manifestation of TB but a potentially lethal one. We present a case of a renal allograft recipient with GITB 18 months after transplant and review other published cases to identify the typical presenting symptoms, risk factors, and natural history. Treatment of GITB is also discussed.

[Patent foramen ovale in the adult: state of the art in 2010]. / Le foramen ovale perméable chez l'adulte: le point en 2010.

A patent foramen ovale (PFO) can be found in 25% of the normal population. Several pathologies have been related to PFO as paradoxical embolism, migraine with aura and decompression illness in divers. Finding a PFO in a young patient suffering a stroke and/or TIA is the most common situation in daily practice and where the therapeutic attitude is most controversial. Should we treat the patient with aspirin, with coumadin or should we proceed to a percutaneous closure? We think that only an open discussion with the patient explaining the pros and contras of each strategy is reasonable, because the only randomised study, CLOSURE I, comparing medical treatment with percutaneous closure has shown no difference between these two strategies in terms of clinical events at two years.

[Transradial approach for coronary angiography and angioplasty: the gold standard]. / Les coronarographies et les angioplasties coronaires par voie radiale: l'approche de choix?

Transradial approach in interventional cardiology is performed heterogenously around the world. Nevertheless, this technique allows to decrease access site complications and major bleeding, and increases patient's comfort. All patient subgroups beneficiate from this approach, especially in the case of acute coronary syndromes in which the bleeding risk is the highest, in relation to aggressive anticoagulation and platelet antiaggregation treatment. Transradial approach requires a longer learning curve than transfemoral approach due to specific technical challenges that are often overcome with experience. Because of its clear benefits, transradial access should become the gold standard approach for coronary diagnostic and interventional procedures.

Robotic transabdominal kidney transplantation in a morbidly obese patient.

Kidney transplantation in morbidly obese patients can be technically demanding. Furthermore, morbidly obese patients experience a high rate of wound infections and related complications, which mostly result from the longer length and extent of the incision. These complications can be avoided through minimally invasive surgery; however, conventional laparoscopic instruments are unsuitable for the safe performance of a kidney transplant in morbidly obese patients. Herein, we report the first minimally invasive, total robotic kidney transplant in a morbidly obese patient. A left, deceased donor kidney was transplanted into a 29-year-old woman with a body mass index (BMI) of 41 kg/m(2) who had been on hemodialysis for 5 years. The operation was performed intraabdominally using the DaVinci Robotic Surgical System with 4 trocars and a 7 cm midline incision. The operative time was 223 min, and the blood loss was less than 50 cc. The kidney had immediate graft function. No perioperative complications were observed, and the patient was discharged on postoperative day 5 with normal kidney function. Minimally invasive access and robotic technology facilitated the safe performance of a successful kidney transplant in a morbidly obese patient.

Attosecond electron spectroscopy using a novel interferometric pump-probe technique.

We present an interferometric pump-probe technique for the characterization of attosecond electron wave packets (WPs) that uses a free WP as a reference to measure a bound WP. We demonstrate our method by exciting helium atoms using an attosecond pulse (AP) with a bandwidth centered near the ionization threshold, thus creating both a bound and a free WP simultaneously. After a variable delay, the bound WP is ionized by a few-cycle infrared laser precisely synchronized to the original AP. By measuring the delay-dependent photoelectron spectrum we obtain an interferogram that contains both quantum beats as well as multipath interference. Analysis of the interferogram allows us to determine the bound WP components with a spectral resolution much better than the inverse of the AP duration.

Lipid metabolism impairment in human gliomas: expression of peroxisomal proteins in human gliomas at different grades of malignancy.

Gliomas are histologically graded by cellularity, cytological atypia, necrosis, mitotic figures, and vascular proliferation, features associated with biologically aggressive behaviour. However, abundant evidence suggests the presence of unrecognized, clinically relevant subclasses of the diffuse gliomas, both in respect to their underlying molecular phenotype and their clinical response to therapy. It is well-known that patient prognosis and therapeutic decisions rely on accurate pathological grading. Recently, it was reported that human gliomas accumulate lipid droplets during progression, suggesting a lipid metabolism impairment. Considering the crucial role of peroxisomes in lipid metabolism, in the present work we studied the expression profiles of proteins either exclusively localized to peroxisomes, such as peroxin14 (PEX14), peroxisomal membrane protein 70Kda (PMP70), acyl-CoA oxidase, thiolase, or partially associated to peroxisomes such as Hydroxymethylglutaryl-CoA reductase (HMGCoA-red) and peroxisomal-related proteins, namely PPARalpha, in human glioma specimens at different grades of malignancy. Moreover, Nile red staining of lipid droplets, thin layer chromatography (TLC) and proton nuclear magnetic resonance spectroscopy (NMR) were carried out in order to correlate the biochemical results with the lipid content of tumor tissues. The results obtained indicate that correlating the malignancy grade with the expression of peroxisomal genes and proteins, may constitute a sensitive tool to highlight possible subtypes not recognized by the classical histological techniques.

Hexagonal array of subunits in tight junctions separated from isolated rat liver plasma membranes.

Solubilization of isolated rat liver plasma membranes in 1% deoxycholate and centrifugation yielded a fraction (pellet) that consisted mainly of tight junctions (zonulae occludentes). An hexagonal array of subunits similar to that previously found in a number of the unfractionated plasma membranes was demonstrated in all the membrane sheets of these preparations by negative staining. It is concluded that the hexagonal subunit pattern is present in the tight junctions, and that this structural differentiation may be related to the intercellular diffusion afforded by the junctional membrane.

Electron microscopic observations of reconstituted proteoliposomes with the purified major intrinsic membrane protein of eye lens fibers.

The purified major intrinsic protein of the lens fiber plasma membrane (MP26) reconstituted into liposomes favored membrane-to-membrane close contacts as visualized by freeze fracture and immunoelectron microscopy. Reconstituted apposed unilamellar vesicles formed pentalaminar profiles, and multilamellar liposomes showed regions of stacked bilayers. Immunogold labeling, using antibody directed against MP26, demonstrated that this polypeptide is present in regions of membrane-to-membrane close interaction. Fracture faces displayed both randomly distributed clusters of 8-nm polygonal intramembrane particles and membrane domains where a bidimensional lattice of repeating subunits was present. The structural pleomorphism which characterized the MP26-reconstituted proteoliposomes seems quite comparable to that visualized in natural fiber plasma membrane domains.

Human multidrug resistance 3-P-glycoprotein expression in transgenic mice induces lens membrane alterations leading to cataract.

We have generated mice transgenic for a human multidrug resistance (MDR)3 mini-gene driven by a hamster vimentin promoter. The MDR3 gene encodes a P-Glycoprotein that resembles the mouse multidrug resistance 2 P-Glycoprotein shown to be involved in the translocation of the phospholipid phosphatidylcholine through the hepatocyte canalicular membrane (Smit et al., 1993. Cell. 75:451-462). The vimentin promoter drives expression of the MDR3 transgene in mesenchymal tissues and in the eye lens. We show here that the presence of human multidrug resistance 3 P-Glycoprotein in the lens results in a severe lenticular pathology. Lens structural abnormalities initiate at a late embryonic stage and increase during postnatal lens development. Differentiation of the primary fibers is affected, and the terminal differentiation of the lens epithelium into secondary fibers is also perturbed. The ultrastructural alterations, particularly of the lens plasma membranes, resemble those identified in congenital mouse osmotic cataract.

[CT coronary angiogram: state of the art in 2009]. / Coronarographie par CT-scan en 2009.

Thanks to 64 multi-detector CT-scan it is nowadays possible to visualise non invasively the coronary arteries: the recently published series have shown excellent sensitivity and specificity in the detection of coronary artery disease. Actually, the principal interest of the technique is the excellent negative predictive value which is very useful to rule out a significant coronary artery stenosis. For the time being, the angio CT is recommended for symptomatic patients with low to intermediate probability of coronary artery disease with inconclusive functional test. Despite some technical ameliorations, the irradiation doses delivered by multi-detector CT are significant and should restrict its indications specifically in women and young patients, in whom a late radio-induced cancer may be a concern.

The polypeptide 310-helix.

The 310-helix, first predicted as a reasonably stable polypeptide secondary structure fifty years ago, has only recently attracted the attention of structural biochemists and protein crystallographers. It represents the third principal structure occurring in globular proteins and has been described at atomic resolution in model peptides and in peptaibol antibiotics.