Academic and Community ICUs Participating in a Critical Care Randomized Trial: A Comparison of Patient Characteristics and Trial Metrics.

Clinical research in Canada is conducted primarily in "academic" hospitals, whereas most clinical care is provided in "community" hospitals. The objective of this nested observational study was to compare patient characteristics, outcomes, process-of-care variables, and trial metrics for patients enrolled in a large randomized controlled trial who were admitted to academic and community hospitals in Canada. DESIGN: We conducted a preplanned observational study nested within the Probiotics: Prevention of Severe Pneumonia and Endotracheal Colonization Trial (PROSPECT, a randomized controlled trial comparing probiotics to placebo in mechanically ventilated patients) Research Program. SETTING: ICUs. PATIENTS: Mechanically ventilated patients. MEASUREMENTS: We compared patient characteristics, interventions, outcomes, and trial metrics between patients enrolled in PROSPECT from academic and community hospitals. MAIN RESULTS: Participating centers included 34 (82.9%) academic and seven (17.1%) community hospitals, which enrolled 2,203 (86.2%) and 352 (13.8%) patients, respectively. Compared with academic hospitals, patients enrolled in community hospitals were older (mean [sd] 62.7 yr [14.9 yr] vs 59.5 yr [16.4 yr]; p = 0.044), had longer ICU stays (median [interquartile range {IQR}], 13 d [8-23 d] vs 11 d [7-8 d]; p = 0.012) and higher mortality (percentage, [95% CI] in the ICU, 30.4% [25.8-35.4%]vs 20.5% [18.9-11.3%]; p = 0.002) and hospital (40.6% [35.6-45.8%] vs 26.1% [24.3-27.9%]; p < 0.001). Trial metrics, including informed consent rate (85.9% vs 76.3%; p = 0.149), mean (sd) monthly enrolment rate (2.1 [1.4] vs 1.1 [0.7]; p = 0.119), and protocol adherence (90.6% vs 91.6%; p = 0.207), were similar between community and academic ICUs. CONCLUSIONS: Community hospitals can conduct high-quality research, with similar trial metrics to academic hospitals. Patient characteristics differed between community and academic hospitals, highlighting the need for broader engagement of community hospitals in clinical research to ensure generalizability of study results.

Perioperative cardiovascular system failure in South Asians undergoing cardiopulmonary bypass is associated with prolonged inflammation and increased Toll-like receptor signaling in inflammatory monocytes.

BACKGROUND: South Asian ethnicity is an independent risk factor for mortality after coronary artery bypass. We tested the hypothesis that this risk results from a greater inflammatory response to cardiopulmonary bypass (CPB). METHODS: This was a single-site prospective cohort study. We compared the inflammatory response to CPB in 20 Caucasians and 17 South Asians undergoing isolated coronary artery bypass grafting surgery. RESULTS: Plasma levels of proinflammatory cytokines (interleukin [IL]-6, IL-8, IL-12, interferon gamma, and tumor necrosis factor) and anti-inflammatory mediators (IL-10 and soluble TNF receptor I) were measured. The Toll-like receptor (TLR) signaling pathway was examined in peripheral blood monocytes by flow cytometry, measuring surface expression of TLR2, TLR4, and coreceptor CD14 and activation of downstream messenger molecules (interleukin-1 receptor-associated kinase 4, nuclear factor kappa from B cells (NF-κB), c-Jun amino-terminal kinase, p38 mitogen-activated protein kinase, and Protein Kinase B). South Asians had persistently higher plasma levels of IL-6 and exhibited increased TLR signaling through the p38 mitogen-activated protein kinase and Protein Kinase B pathways in inflammatory monocytes after CPB. This increased inflammatory response was paralleled clinically by a higher sequential organ failure assessment score (5.1 ± 1.4 versus 1.5 ± 1.6, P = 0.027) and prolonged cardiovascular system failure (23.5% versus 0%) 48 h after CPB. CONCLUSIONS: South Asians develop an exacerbated systemic inflammatory response after CPB, which may contribute to the higher morbidity and mortality associated with coronary artery bypass in this population. These patients may benefit from targeted anti-inflammatory therapies designed to mitigate the adverse consequences resulting from this response.

Inhibition of T cell protein tyrosine phosphatase enhances interleukin-18-dependent hematopoietic stem cell expansion.

The clinical application of hematopoietic progenitor cell-based therapies for the treatment of hematological diseases is hindered by current protocols, which are cumbersome and have limited efficacy to augment the progenitor cell pool. We report that inhibition of T-cell protein tyrosine phosphatase (TC-PTP), an enzyme involved in the regulation of cytokine signaling, through gene knockout results in a ninefold increase in the number of hematopoietic progenitors in murine bone marrow (BM). This effect could be reproduced using a short (48 hours) treatment with a pharmacological inhibitor of TC-PTP in murine BM, as well as in human BM, peripheral blood, and cord blood. We also demonstrate that the ex vivo use of TC-PTP inhibitor only provides a temporary effect on stem cells and did not alter their capacity to reconstitute all hematopoietic components in vivo. We establish that one of the mechanisms whereby inhibition of TC-PTP mediates its effects involves the interleukin-18 (IL-18) signaling pathway, leading to increased production of IL-12 and interferon-gamma by progenitor cells. Together, our results reveal a previously unrecognized role for IL-18 in contributing to the augmentation of the stem cell pool and provide a novel and simple method to rapidly expand progenitor cells from a variety of sources using a pharmacological compound.

Modulation of bone marrow-derived endothelial progenitor cell activity by protein tyrosine phosphatases.

Adult bone marrow contains stem cells capable of reconstituting the vascular system. The ordered progression of stem cells and more differentiated endothelial precursor cells through successive developmental stages is tightly controlled. The specialized microenvironment of the bone marrow as well as cell-autonomous processes directs the renewal and differentiation of stem cells into endothelial cells. Tyrosine phosphorylation of receptors, adaptors, and structural proteins is one mechanism whereby endothelial cell development is regulated, which involves the opposing action of protein tyrosine kinases and phosphatases. The present review focuses on the role of four nontransmembrane protein tyrosine phosphatases (TC-PTP, PTP1B, SHP-1, and SHP-2) in the self-renewal, differentiation, mobilization, and homing of endothelial progenitor cells, as well as their ability to incorporate into nascent blood vessels. Endothelial progenitor cells are known to promote vasculogenesis, accelerating restoration of blood flow to ischemic tissues, and improve cardiac function after infarct. The use of protein tyrosine phosphatase inhibitors to modulate the development and function of endothelial progenitor cells as a potential novel therapy for peripheral vascular and coronary artery disease in humans is discussed.

Esophageal-left atrial fistula: intraoperative diagnosis and management.

Nontraumatic esophageal-atrial fistulas are usually fatal and are diagnosed postmortem. We report a rare case of intraoperative diagnosis and successful surgical management of an esophageal-left atrial fistula in a 70-year-old woman with a history of brachytherapy, radiotherapy, and chemotherapy for esophageal cancer who presented with progressive dysphagia and hematemesis.

Low activation threshold as a mechanism for ligand-independent signaling in pre-T cells.

Pre-TCR complexes are thought to signal in a ligand-independent manner because they are constitutively targeted to lipid rafts. We report that ligand-independent signaling is not a unique capability of the pre-TCR complex. Indeed, the TCR alpha subunit restores development of pT alpha-deficient thymocytes to the CD4(+)CD8(+) stage even in the absence of conventional MHC class I and class II ligands. Moreover, we found that pre-TCR and alpha beta TCR complexes exhibit no appreciable difference in their association with lipid rafts, suggesting that ligand-independence is a function of the CD4(-)CD8(-) (DN) thymocytes in which pre-TCR signaling occurs. In agreement, we found that only CD44(-)CD25(+) DN thymocytes (DN3) enabled activation of extracellular signal-regulated kinases by the pre-TCR complex. DN thymocytes also exhibited a lower signaling threshold relative to CD4(+)CD8(+) thymocytes, which was associated with both the markedly elevated lipid raft content of their plasma membranes and more robust capacitative Ca(2+) entry. Taken together these data suggest that cell-autonomous, ligand-independent signaling is primarily a property of the thymocytes in which pre-TCR signaling occurs.