Pandemic influenza viruses often cause severe disease in middle-aged adults without preexistent co-morbidities. The mechanism of illness associated with severe disease in this age group is not well understood1–10. Here, we demonstrate preexisting serum antibody that cross-reacts with, but does not protect against 2009 H1N1 influenza virus in middle-aged adults. Non-protective antibody is associated with immune complex(IC)-mediated disease after infection. High titers of serum antibody of low avidity for H1-2009 antigen, and low avidity pulmonary ICs against the same protein were detected in severely ill patients. Moreover, C4d deposition - a sensitive marker of complement activation mediated by ICs- was present in lung sections of fatal cases. Archived lung sections from adults with confirmed fatal influenza 1957 H2N2 infection revealed a similar mechanism of illness. These observations provide a novel biological mechanism for the unusual age distribution of severe cases during influenza pandemics.

The objective of this study was to assess the impact on outcome of adjuvant therapy (high-dose of immunoglobulin [Ig] M-enriched intravenous Ig, IVIG) in intensive care unit (ICU) patients who underwent surgery by abdominal sepsis. This was a prospective, randomized, double-blind, controlled study set in the medical/surgical ICUs of seven teaching hospitals. Patients with severe sepsis and septic shock of intra-abdominal origin admitted to the ICU within 24 h after the onset of symptoms were included in the study. Polyvalent IgM-enriched Ig (Pentaglobin; IVIG group) at a dosage of 7 mL/kg/day for 5 days or an equal amount of 5% human albumin (control group) was randomized. Fifty-six patients were enrolled. The overall mortality rate was 37.5.%. Twenty patients had shock and 36 had severe sepsis (the mortality rate was 55.0% and 25.0%, respectively). In the intent-to-treat analysis, the mortality rate was reduced from 48.1% in patients treated with antibiotic (ATB) plus albumin to 27.5% (P = 0.06) for patients with ATB plus IVIG. The organ failure score (1.0 +/- 0.6 vs. 1.2 +/- 0.9), organ dysfunction score (1.7 +/- 1.1 vs. 1.8 +/- 1.0), and reoperation rate (17.2% vs. 29.6%) were not different between IVIG and control groups, respectively. Eight patients (14.3%) received inappropriate ATB initial therapy (IAT), and seven died (87.5%). IAT was the only variable independently associated with death (odds ratio, 19.4) in a logistic regression model. We conclude that IVIG administration, when used in combination with adequate antibiotics, improved the survival of surgical ICU patients with intra-abdominal sepsis. The initial choice of antibiotic has a dramatic impact on outcome.

Stem cells derived from placental tissues are an attractive source of cells for regenerative medicine. Amniotic epithelial cells isolated from human amnion (hAECs) have desirable and competitive characteristics that make them stand out between other stem cells. They have the ability to differentiate toward all three germ layers, they are not tumorigenic and they have immunosuppressive properties. Although liver transplantation is the best way to treat acute and chronic hepatic failure patients, there are several obstacles. Recently, stem cells have been spotlighted as alternative source of hepatocytes because of their potential for hepatogenic differentiation. In this work, we aimed to study the proliferation and survival of the hAECs during their hepatic differentiation. We have also analyzed the changes in pluripotency and hepatic markers. We differentiated amniotic cells applying a specific hepatic differentiation (HD) protocol. We determined by qRT-PCR that hAECs express significant levels of SOX-2, OCT-4 and NANOG during at least 15 days in culture and these pluripotent markers diminish during HD. SSEA-4 expression was reduced during HD, measured by immunofluorescence. Morphological characteristics became more similar to hepatic ones in differentiated cells and representative hepatic markers significantly augmented their expression, measured by qRT-PCR and Western blot. Cells achieved a differentiation efficiency of 75%. We observed that HD induced proliferation and promoted survival of hAECs, during 30 days in culture, evaluated by 3H-thymidine incorporation and MTT assay. HD also promoted changes in hAECs cell cycle. Cyclin D1 expression increased, while p21 and p53 levels were reduced. Immunofluorescence analysis showed that Ki-67 expression was upregulated during HD. Finally, ERK 1/2 phosphorylation, which is intimately linked to proliferation and cell survival, augmented during all HD process and the inhibition of this signaling pathway affected not only proliferation but also differentiation. Our results suggest that HD promotes proliferation and survival of hAECs, providing important evidence about the mechanisms governing their hepatic differentiation. We bring new knowledge concerning some of the optimal transplantation conditions for these hepatic like cells.

Acinetobacter spp. and Pseudomonas aeruginosa are common pathogens of ventilator-associated pneumonia (VAP). The presentation and outcome of VAP due to Acinetobacter spp. and P. aeruginosa susceptible to carbapenems (Carb-S; imipenem and/or meropenem) and to colistin only (Col-S) were compared in the present retrospective study in three intensive care units.A total of 61 episodes of VAP caused by Acinetobacter spp. or P. aeruginosa were studied, of which 30 isolates were Carb-S and 31 were Col-S.Demographics, worsening of renal function and mortality were not different. The univariate analysis showed that a later onset and a previous episode of VAP, prior antimicrobial therapy for .10 days and previous therapy with carbapenems during the present admission were more frequent in patients with Col-S strains. On multivariate analysis, prior antimicrobial therapy for .10 days and a previous episode of VAP remained significantly associated with Col-S VAP. Approximately 41% of the infections caused by Col-S isolates, but none of those due to Carb-S isolates, had received prior carbapenem therapy.Colistin-susceptible ventilator-associated pneumonia episodes can be effectively treated using colistin without significant renal dysfunction. This susceptibility pattern could be suspected in patients with a previous ventilator-associated pneumonia episode or prior antibiotic therapy for .10 days preceding the present ventilator-associated pneumonia episode.

SummaryThe effect of positive end-expiratory pressure (PEEP) on intracranial pressure (lCP) and cerebral perfusion pressure (CPP) has been reported by several investigators, without any consensus being reached. Acute neurological and neurosurgical patients suffer intracranial hypertension and acute lung injury with hypoxemia. Since PEEP may improve hypoxemia but elevate ICP and decrease CPP, it is important to determine the influence of varying levels of PEEP on ICP and CPP. The aim of the study was to investigate the changes in ICP and CPP associated with different levels of PEEP. Twenty patients requiring ICP monitoring and mechanical ventilation were enrolled. Patients had severe head injury (n = 10), spontaneous intracerebral haemorrhage (n = 5), and subarachnoid haemorrhage (n = 5). PEEP was raised from 5 (basal) to 15 cm H 20 in steps of 5 cm H20. After at least 10 minutes of each new PEEP setting, ICP and CPP were measured. PEEP at 10 and 15 cm H20 produced a significant (p < 0.05) increase in intracranial pressure 11.6 ± 5.6 and 14.6 ± 6.28 mm Hg, respectively; no significant (p = 0.819) change occurred in CPP.