An RNA stem-loop functions in conjunction with an upstream open reading frame to direct preferential translation in the integrated stress response.

In response to environmental stresses, cells invoke translational control to conserve resources and rapidly reprogram gene expression for optimal adaptation. A central mechanism for translational control involves phosphorylation of the α subunit of eIF2 (p-eIF2α), which reduces delivery of initiator tRNA to ribosomes. Because p-eIF2α is invoked by multiple protein kinases, each responding to distinct stresses, this pathway is named the integrated stress response (ISR). While p-eIF2α lowers bulk translation initiation, many stress-related mRNAs are preferentially translated. The process by which ribosomes delineate gene transcripts for preferential translation is known to involve upstream open reading frames (uORFs) embedded in the targeted mRNAs. In this study, we used polysome analyses and reporter assays to address the mechanisms directing preferential translation of human IBTKα in the ISR. The IBTKα mRNA encodes four uORFs, with only 5'-proximal uORF1 and uORF2 being translated. Of importance, the 5'-leader of IBTKα mRNA also contains a phylogenetically conserved stem-loop of moderate stability that is situated 11 nucleotides downstream of uORF2. The uORF2 is well translated and functions in combination with the stem-loop to effectively lower translation reinitiation at the IBTKα coding sequence. Upon stress-induced p-eIF2α, the uORF2/stem loop element can be bypassed to enhance IBTKα translation by a mechanism that may involve the modestly translated uORF1. Our study demonstrates that uORFs in conjunction with RNA secondary structures can be critical elements that serve as the "bar code" by which scanning ribosomes can delineate which mRNAs are preferentially translated in the ISR.

GCN2 eIF2 kinase promotes prostate cancer by maintaining amino acid homeostasis.

A stress adaptation pathway termed the integrated stress response has been suggested to be active in many cancers including prostate cancer (PCa). Here, we demonstrate that the eIF2 kinase GCN2 is required for sustained growth in androgen-sensitive and castration-resistant models of PCa both in vitro and in vivo, and is active in PCa patient samples. Using RNA-seq transcriptome analysis and a CRISPR-based phenotypic screen, GCN2 was shown to regulate expression of over 60 solute-carrier (SLC) genes, including those involved in amino acid transport and loss of GCN2 function reduces amino acid import and levels. Addition of essential amino acids or expression of 4F2 (SLC3A2) partially restored growth following loss of GCN2, suggesting that GCN2 targeting of SLC transporters is required for amino acid homeostasis needed to sustain tumor growth. A small molecule inhibitor of GCN2 showed robust in vivo efficacy in androgen-sensitive and castration-resistant mouse models of PCa, supporting its therapeutic potential for the treatment of PCa.

Prostate cancer is the fourth most common cancer worldwide, affecting over a million people each year. Existing drug treatments work by blocking the effects or reducing the levels of the hormone testosterone. However, these drug regimens are not always effective, so finding alternative treatments is an important area of research. One option is to target the 'integrated stress response', a pathway that acts as a genetic switch, turning on a group of genes that counteract cellular stress and are essential for the survival of cancer cells. The reason cancer cells are under stress is because they are hungry. They need to make a lot of proteins and other metabolic intermediates to grow and divide, which means they need plenty of amino acids, the building blocks that make up proteins and fuel metabolism. Amino acids enter cells through molecular gates called amino acid transporters, and scientists think the integrated stress response might play a role in this process. One of the integrated stress response components is a protein called General Control Nonderepressible 2, or GCN2 for short. In healthy cells, this protein helps to boost amino acid levels when supplies start to run low. Cordova et al. examined human prostate cancer cells to find out what role GCN2 plays in this cancer. In both lab-grown cells and tissue from patients, GCN2 was active and played a critical role in prostate tumor growth by turning on the genes for amino acid transporters to increase the levels of amino acids entering the cancer cells. Deleting the gene for GCN2, or blocking its effects with an experimental drug, slowed the growth of cultured prostate cancer cells and reduced tumor growth in mice. In these early experiments, Cordova et al. did not notice any toxic side effects to healthy tissues. If GCN2 works in the same way in humans as it does in mice, blocking it might help to control prostate cancer growth. The integrated stress response is also active in other cancer types, so the same logic might apply to different tumors. However, before GCN2 blockers can become treatments, researchers need a more complete understanding of their molecular effects.

The eIF2 kinase GCN2 directs keratinocyte collective cell migration during wound healing via coordination of reactive oxygen species and amino acids.

Healing of cutaneous wounds requires the collective migration of epithelial keratinocytes to seal the wound bed from the environment. However, the signaling events that coordinate this collective migration are unclear. In this report, we address the role of phosphorylation of eukaryotic initiation factor 2 (eIF2) and attendant gene expression during wound healing. Wounding of human keratinocyte monolayers in vitro led to the rapid activation of the eIF2 kinase GCN2. We determined that deletion or pharmacological inhibition of GCN2 significantly delayed collective cell migration and wound closure. Global transcriptomic, biochemical, and cellular analyses indicated that GCN2 is necessary for maintenance of intracellular free amino acids, particularly cysteine, as well as coordination of RAC1-GTP-driven reactive oxygen species (ROS) generation, lamellipodia formation, and focal adhesion dynamics following keratinocyte wounding. In vivo experiments using mice deficient for GCN2 validated the role of the eIF2 kinase during wound healing in intact skin. These results indicate that GCN2 is critical for appropriate induction of collective cell migration and plays a critical role in coordinating the re-epithelialization of cutaneous wounds.

TgIF2K-B Is an eIF2α Kinase in Toxoplasma gondii That Responds to Oxidative Stress and Optimizes Pathogenicity.

Toxoplasma gondii is an obligate intracellular parasite that persists in its vertebrate hosts in the form of dormant tissue cysts, which facilitate transmission through predation. The parasite must strike a balance that allows it to disseminate throughout its host without killing it, which requires the ability to properly counter host cell defenses. For example, oxidative stress encountered by Toxoplasma is suggested to impair parasite replication and dissemination. However, the strategies by which Toxoplasma mitigates oxidative stress are not yet clear. Among eukaryotes, environmental stresses induce the integrated stress response via phosphorylation of a translation initiation factor, eukaryotic initiation factor 2 (eIF2). Here, we show that the Toxoplasma eIF2 kinase TgIF2K-B is activated in response to oxidative stress and affords protection. Knockout of the TgIF2K-B gene, Δtgif2k-b, disrupted parasite responses to oxidative stresses and enhanced replication, diminishing the ability of the parasite to differentiate into tissue cysts. In addition, parasites lacking TgIF2K-B exhibited resistance to activated macrophages and showed greater virulence in an in vivo model of infection. Our results establish that TgIF2K-B is essential for Toxoplasma responses to oxidative stress, which are important for the parasite's ability to establish persistent infection in its host.IMPORTANCEToxoplasma gondii is a single-celled parasite that infects nucleated cells of warm-blooded vertebrates, including one-third of the human population. The parasites are not cleared by the immune response and persist in the host by converting into a latent tissue cyst form. Development of tissue cysts can be triggered by cellular stresses, which activate a family of TgIF2 kinases to phosphorylate the eukaryotic translation initiation factor TgIF2α. Here, we establish that the TgIF2 kinase TgIF2K-B is activated by oxidative stress and is critical for maintaining oxidative balance in the parasite. Depletion of TgIF2K-B alters gene expression, leading to accelerated growth and a diminished ability to convert into tissue cysts. This study establishes that TgIF2K-B is essential for the parasite's oxidative stress response and its ability to persist in the host as a latent infection.

Toxoplasma gondii Co-opts the Unfolded Protein Response To Enhance Migration and Dissemination of Infected Host Cells.

Toxoplasma gondii is an intracellular parasite that reconfigures its host cell to promote pathogenesis. One consequence of Toxoplasma parasitism is increased migratory activity of host cells, which facilitates dissemination. Here, we show that Toxoplasma triggers the unfolded protein response (UPR) in host cells through calcium release from the endoplasmic reticulum (ER). We further identify a novel role for the host ER stress sensor protein IRE1 in Toxoplasma pathogenesis. Upon infection, Toxoplasma activates IRE1, engaging its noncanonical role in actin remodeling through the binding of filamin A. By inducing cytoskeletal remodeling via IRE1 oligomerization in host cells, Toxoplasma enhances host cell migration in vitro and dissemination of the parasite to host organs in vivo Our study has identified novel mechanisms used by Toxoplasma to induce dissemination of infected cells, providing new insights into strategies for treatment of toxoplasmosis.IMPORTANCE Cells that are infected with the parasite Toxoplasma gondii exhibit heightened migratory activity, which facilitates dissemination of the infection throughout the body. In this report, we identify a new mechanism used by Toxoplasma to hijack its host cell and increase its mobility. We further show that the ability of Toxoplasma to increase host cell migration involves not the enzymatic activity of IRE1 but rather IRE1 engagement with actin cytoskeletal remodeling. Depletion of IRE1 from infected host cells reduces their migration in vitro and significantly hinders dissemination of Toxoplasma in vivo Our findings reveal a new mechanism underlying host-pathogen interactions, demonstrating how host cells are co-opted to spread a persistent infection around the body.

Regulation of arginine transport by GCN2 eIF2 kinase is important for replication of the intracellular parasite Toxoplasma gondii.

Toxoplasma gondii is a prevalent protozoan parasite that can infect any nucleated cell but cannot replicate outside of its host cell. Toxoplasma is auxotrophic for several nutrients including arginine, tryptophan, and purines, which it must acquire from its host cell. The demands of parasite replication rapidly deplete the host cell of these essential nutrients, yet Toxoplasma successfully manages to proliferate until it lyses the host cell. In eukaryotic cells, nutrient starvation can induce the integrated stress response (ISR) through phosphorylation of an essential translation factor eIF2. Phosphorylation of eIF2 lowers global protein synthesis coincident with preferential translation of gene transcripts involved in stress adaptation, such as that encoding the transcription factor ATF4 (CREB2), which activates genes that modulate amino acid metabolism and uptake. Here, we discovered that the ISR is induced in host cells infected with Toxoplasma. Our results show that as Toxoplasma depletes host cell arginine, the host cell phosphorylates eIF2 via protein kinase GCN2 (EIF2AK4), leading to induced ATF4. Increased ATF4 then enhances expression of the cationic amino acid transporter CAT1 (SLC7A1), resulting in increased uptake of arginine in Toxoplasma-infected cells. Deletion of host GCN2, or its downstream effectors ATF4 and CAT1, lowers arginine levels in the host, impairing proliferation of the parasite. Our findings establish that Toxoplasma usurps the host cell ISR to help secure nutrients that it needs for parasite replication.

Adducins inhibit lung cancer cell migration through mechanisms involving regulation of cell-matrix adhesion and cadherin-11 expression.

Cell migration is a critical mechanism controlling tissue morphogenesis, epithelial wound healing and tumor metastasis. Migrating cells depend on orchestrated remodeling of the plasma membrane and the underlying actin cytoskeleton, which is regulated by the spectrin-adducin-based membrane skeleton. Expression of adducins is altered during tumorigenesis, however, their involvement in metastatic dissemination of tumor cells remains poorly characterized. This study investigated the roles of α-adducin (ADD1) and γ-adducin (ADD3) in regulating migration and invasion of non-small cell lung cancer (NSCLC) cells. ADD1 was mislocalized, whereas ADD3 was markedly downregulated in NSCLC cells with the invasive mesenchymal phenotype. CRISPR/Cas9-mediated knockout of ADD1 and ADD3 in epithelial-type NSCLC and normal bronchial epithelial cells promoted their Boyden chamber migration and Matrigel invasion. Furthermore, overexpression of ADD1, but not ADD3, in mesenchymal-type NSCLC cells decreased cell migration and invasion. ADD1-overexpressing NSCLC cells demonstrated increased adhesion to the extracellular matrix (ECM), accompanied by enhanced assembly of focal adhesions and hyperphosphorylation of Src and paxillin. The increased adhesiveness and decreased motility of ADD1-overexpressing cells were reversed by siRNA-mediated knockdown of Src. By contrast, the accelerated migration of ADD1 and ADD3-depleted NSCLC cells was ECM adhesion-independent and was driven by the upregulated expression of pro-motile cadherin-11. Overall, our findings reveal a novel function of adducins as negative regulators of NSCLC cell migration and invasion, which could be essential for limiting lung cancer progression and metastasis.

Recreational Marijuana Use and Acute Myocardial Infarction: Insights from Nationwide Inpatient Sample in the United States.

Background Marijuana is a widely used recreational substance. Few cases have been reported of acute myocardial infarction following marijuana use. To our knowledge, this is the first ever study analyzing the lifetime odds of acute myocardial infarction (AMI) with marijuana use and the outcomes in AMI patients with versus without marijuana use. Methods We queried the 2010-2014 National Inpatient Sample (NIS) database for 11-70-year-old AMI patients. Pearson Chi-square test for categorical variables and Student T-test for continuous variables were used to compare the baseline demographic and hospital characteristics between two groups (without vs. with marijuana) of AMI patients. The univariate and multivariate analyses were used to assess and compare the clinical outcomes between two groups. We used Cochran-Armitage test to measure the trends. All statistical analyses were executed by IBM SPSS Statistics 22.0 (IBM Corp., Armonk, NY). We used weighted data to produce national estimates in our study. Results Out of 2,451,933 weighted hospitalized AMI patients, 35,771 patients with a history of marijuana and 2,416,162 patients without a history of marijuana use were identified. The AMI-marijuana group consisted more of younger, male, African American patients. The length of stay and mortality rate were lower in the AMI-marijuana group with more patients being discharged against medical advice. Multivariable analysis showed that marijuana use was a significant risk factor for AMI development when adjusted for age, sex, race (adjusted OR 1.079, 95% CI 1.065-1.093, p<0.001); adjusted for age, female, race, smoking, cocaine abuse (adjusted OR 1.041, 95% CI 1.027-1.054, p<0.001); and also when adjusted for age, female, race, payer status, smoking, cocaine abuse, amphetamine abuse and alcohol abuse (adjusted OR: 1.031, 95% CI: 1.018-1.045, p<0.001). Complications such as respiratory failure (OR 18.9, CI 15.6-23.0, p<0.001), cerebrovascular disease (OR 9.0, CI 7.0-11.7, p<0.001), cardiogenic shock (OR 6.0, CI 4.9-7.4, p<0.001), septicemia (OR 1.8, CI 1.5-2.2, p<0.001), and dysrhythmia (OR 1.8, CI 1.5-2.1, p<0.001) were independent predictors of mortality in AMI-marijuana group. Conclusion The lifetime AMI odds were increased in recreational marijuana users. Overall odds of mortality were not increased significantly in AMI-marijuana group. However, marijuana users showed higher trends of AMI prevalence and related mortality from 2010-2014. It is crucial to assess cardiovascular effects related to marijuana overuse and educate patients for the same.

Krüppel-Like Transcription Factor KLF1 Is Required for Optimal γ- and ß-Globin Expression in Human Fetal Erythroblasts.

In human adult erythroid cells, lower than normal levels of Krüppel-like transcription factor 1 (KLF1) are generally associated with decreased adult ß- and increased fetal γ-globin gene expression. KLF1 also regulates BCL11A, a known repressor of adult γ-globin expression. In seeming contrast to the findings in adult cells, lower amounts of KLF1 correlate with both reduced embryonic and reduced fetal ß-like globin mRNA in mouse embryonic erythroid cells. The role of KLF1 in primary human fetal erythroid cells, which express both γ- and ß-globin mRNA, is less well understood. Therefore, we studied the role of KLF1 in ex vivo differentiated CD34+ umbilical cord blood cells (UCB erythroblasts), representing the fetal milieu. In UCB erythroblasts, KLF1 binds to the ß-globin locus control region (LCR), and the ß-globin promoter. There is very little KLF1 binding detectable at the γ-globin promoter. Correspondingly, when cultured fetal UCB erythroblasts are subjected to lentiviral KLF1 knockdown, the active histone mark H3K4me3 and RNA pol II recruitment are diminished at the ß- but not the γ-globin gene. The amount of KLF1 expression strongly positively correlates with ß-globin mRNA and weakly positively correlates with BCL11A mRNA. With modest KLF1 knockdown, mimicking haploinsufficiency, γ-globin mRNA is increased in UCB erythroblasts, as is common in adult cells. However, a threshold level of KLF1 is evidently required, or there is no absolute increase in γ-globin mRNA in UCB erythroblasts. Therefore, the role of KLF1 in γ-globin regulation in fetal erythroblasts is complex, with both positive and negative facets. Furthermore, in UCB erythroblasts, diminished BCL11A is not sufficient to induce γ-globin in the absence of KLF1. These findings have implications for the manipulation of BCL11A and/or KLF1 to induce γ-globin for therapy of the ß-hemoglobinopathies.

Hybrid arch debranching and endograft repair in a patient with a ruptured thoracic aortic aneurysm.

Recent advances in hybrid techniques of aortic arch debranching allow for the repair of thoracic aortic arch aneurysm without requiring cardiopulmonary bypass or hypothermic circulatory arrest. We describe the repair of a ruptured proximal descending thoracic aortic aneurysm, using off-pump aortic arch debranching and antegrade transaortic deployment of a thoracic endograft in an elderly patient.

Endovascular recanalization of total occlusions of the mesenteric and celiac arteries.

OBJECTIVE: To evaluate our experience with the endovascular treatment of total occlusions of the mesenteric and celiac arteries. METHODS: We performed a retrospective review of endovascular stenting of 27 nonembolic total occlusions of the superior mesenteric artery (SMA) and celiac artery (CA) between July 2004 and July 2011 (26 patients, 16 females; mean age, 62 ± 13 years). A variety of demographic, lesion-related and procedure-related variables were evaluated for potential impact of technical success and patency. The follow-up protocol included clinical assessment, and color and spectral Doppler evaluation of the stented vessel(s). RESULTS: The clinical presentation was chronic mesenteric ischemia in 12 patients, acute mesenteric vascular syndromes in 10 patients, foregut ischemia/ischemic pancreatitis in three patients, and prior to endovascular repair of aortic aneurysm in one patient. The treated vessel was SMA in 22 procedures, CA in three, and both SMA and CA in one. Technical success was achieved in 23 of the 27 attempted recanalizations (85%). Three patients who failed the attempt underwent open bypass, and another one underwent retrograde recanalization and stenting of the SMA. Procedure success was only significantly related to patient age <70 years or procedure performance after the year 2006. Notably, the presence of a stump, ostial plaque, extensive vascular calcification, recanalization route (intraluminal vs subintimal), occlusion length, and vessel diameter had no significant impact on procedure success. Traditional duplex criteria proved unreliable in predicting restenosis. Life table analysis of freedom from symptom recurrence showed a primary and assisted rates of 58% and 80% at 1 year, and 33% and 60% at 2 years, respectively. Clinical recurrences developed in six patients (four presented with abdominal angina and weight loss, two presented with abdominal catastrophe). There were six access-related complications and no procedural deaths. Four delayed deaths occurred during follow-up (two cardiac causes, two due to abdominal sepsis). CONCLUSIONS: Endovascular recanalization of mesenteric artery occlusion is both feasible and successful, provided careful planning is used.

Anatomic bifurcated reconstruction of chronic bilateral innominate-superior vena cava occlusion using the Y-stenting technique.

This article presents the case of a 42-year-old man who presented with superior vena cava (SVC) syndrome due to fibrosing mediastinitis with multiple failed attempts at recanalization. We initially treated him with unilateral sharp needle recanalization of the right innominate vein into the SVC stump followed by stenting. Although his symptoms improved immediately, they did not completely resolve. Six months later, he returned with worsening symptoms, and venography revealed in-stent restenosis. The patient requested simultaneous treatment on the left side. The right stent was dilated, and a 3-cm-long occlusion of the left innominate vein was recanalized, again using sharp needle technique, homing into the struts of the right-sided stent. Following fenestration of the stent, a second stent was deployed from the left side into the SVC, and the two Y limbs were sequentially dilated to allow a true bifurcation anatomy (figure). The patient had complete resolution of his symptoms and continues to do well 6 months later.

Prophylactic antibiotic days as a predictor of sensitivity patterns in Acinetobacter pneumonia.

BACKGROUND: Ventilator-associated pneumonia (VAP) secondary to Acinetobacter spp. in critically ill trauma patients has increased. More importantly, the incidence of multi-drug-resistant (MDR) Acinetobacter VAP has increased. The risk factors for this increase in resistance have yet to be elucidated. The purpose of this study was to evaluate the change in Acinetobacter sensitivity over time and determine which risk factors predict resistance in trauma patients. METHODS: Patients surviving >5 days post-injury who had Acinetobacter VAP (≥10(5) colony-forming units/mL in bronchoalveolar lavage fluid) who were seen over five years were divided according to pathogen sensitivity (sensitive [SEN] vs. MDR) and stratified by age, severity of shock (base excess, number of blood transfusions), injury severity (Injury Severity Score [ISS], admission Glasgow Coma Scale [GCS] score, chest and extremity Abbreviated Injury Scale score [AIS]), and year. Prophylactic (Pro), empiric (Emp), Pro + Emp, and total antibiotic days, ventilator days, and mortality rate were compared. Multivariable logistic regression (MLR) was performed to determine which risk factors were independent predictors of resistance. RESULTS: Ninety-six patients (81% male) were identified: 62 SEN and 34 MDR. The groups were clinically similar in terms of age, extent of shock, and injury severity with the exception of extremity AIS. Antibiotic exposure was greater in the MDR group. Over the period of the study, the incidence of MDR Acinetobacter VAP increased from zero to 66% (p < 0.0001). Multiple logistic regression identified Pro antibiotic days as an independent predictor of MDR after adjusting for age and chest AIS (p < 0.0001). CONCLUSIONS: The incidence of MDR Acinetobacter VAP has increased over time. More severe extremity injuries, as measured by the AIS, may contribute to prolonged antibiotic exposure in those patients with MDR Acinetobacter VAP. Multiple logistic regression identified Pro antibiotic days as an independent risk factor for MDR Acinetobacter VAP in trauma patients.

Secretory immunoglobulin A abrogates inflammatory responses and improves mortality after pseudomonas pneumonia.

BACKGROUND: Secretory immunoglobulin A (SIgA) is the principle antibody at respiratory and other mucosal sites. Its concentration in mucosal secretions is influenced by route of nutrition and insults common to the trauma patient. SIgA has anti-inflammatory effects, which may protect against exaggerated inflammatory responses after infection. Polyimmunoglobulin receptor (pIgR) knockout (KO) mice, which do not have SIgA in mucosal secretions but are otherwise immunologically intact, were used to study the importance of SIgA in respiratory secretions after bacterial pneumonia. METHODS: Pseudomonas aeruginosa or phosphate-buffered saline was administered intratracheally to pIgR-KO or conventional mice. Mortality was noted at 72 hours. Surviving animals were killed and blood, lung, and bronchoalveolar lavage (BAL) fluid samples were obtained and analyzed for myeloperoxidase, cytokine, and IgG levels. RESULTS: Pneumonia was associated with increases in blood and bronchoalveolar lavage cytokine levels and increased lung myeloperoxidase activity. These results were significantly greater in pIgR-KO mice and associated with a threefold increase in mortality. CONCLUSION: The importance of SIgA in maintaining mucosal homeostasis is demonstrated in this study, and the study supports efforts to preserve mucosal immune function in the trauma patient.

Sequence of immunoglobulin isotype exposure modulates inflammatory response to bacteria and lipopolysaccharide in vitro.

BACKGROUND: Secretory immunoglobulin A (sIgA) and immunoglobulin G (IgG) are the principal immunoglobulins in the respiratory tract. Under normal circumstances, the upper respiratory tract contains predominantly sIgA, whereas IgG is of primary importance in the lower tract. Unlike other antibody isotypes, IgA antibodies participate in host defense functions without inciting inflammatory processes that might cause collateral damage to tissues. However, the ability of sIgA to modulate inflammatory reactions induced by other humoral factors is unclear. We examined the effect of the sequence of exposure to the two immunoglobulin isotypes on bacteria- or lipopolysaccharide (LPS)-mediated cytokine production by monocyte-polymorphonuclear neutrophil (PMN) cells in vitro. METHODS: Blood monocytes were co-cultured with Escherichia coli or LPS. Either sIgA or IgG was added to subsets of cultures, which were incubated for 1 h at 37 degrees C. Culture supernatant liquids were then co-cultured with naïve PMNs for 1 h at 37 degrees C. Either IgG was added during this co-culture step or sIgA was added if IgG was added first. Cytokines were quantitated by enzyme-linked immunosorbent assay. RESULTS: Significant increases in interleukin (IL)-6, tumor necrosis factor (TNF)-alpha, and IL-8 were noted after E. coli or LPS co-culture with monocytes and subsequent PMN challenge. Marked decreases in these pro-inflammatory cytokines were seen after the addition of sIgA or sIgA-IgG but not after IgG alone. This effect was more apparent with the immunoglobulin sequence IgA followed by IgG. CONCLUSION: The sequence of immunoglobulin isotype involvement in infectious processes is important in modulating the cytokine response to bacteria and LPS by inflammatory cells. Our in vitro results support the critical role of sIgA in the proximal airways in mitigating inflammatory responses by other humoral defenses in the distal airways. Loss of effective sIgA function may contribute to increased morbidity and deaths from nosocomial pneumonia in compromised patients.

Conversion of intestinal bypass to Roux-en-Y gastric bypass: a case report and brief review.

Intestinal bypass procedures for the treatment of morbid obesity have been largely replaced by Roux-en-Y gastric bypass procedures. The main reason for this change over the past 40 years stems from the myriad of negative nutritional and physiologic repercussions of intestinal bypass procedures. We present a case of a patient with severely atrophied small bowel and the novel method used for the conversion of the intestinal bypass procedure to Roux-en-Y gastric bypass. Additionally, we present a brief review of jejunoileal bypass.

Benign fibroepithelial polyp arising in the bronchus: a case report and review of the literature.

Benign endobronchial polyps are rare findings that present a diagnostic dilemma not only for the clinician but also for the pathologist. We describe a man with repeated visits to emergency departments for coughing spells who ultimately underwent bronchoscopy and biopsy. The biopsy specimen was initially diagnosed as a leiomyoma, but the final pathologic diagnosis of the gross specimen was a benign fibroepithelial polyp. We present the clinical history of this patient along with a brief review of the published literature regarding this rare clinical entity.

Dose-dependent effects of ethanol and E. coli on gut permeability and cytokine production.

INTRODUCTION: The gut may prime inflammatory responses following shock/trauma insults. Ethanol (EtOH) use is common in trauma patients and may impair intestinal barrier function. We compared varying concentrations of EtOH on proinflammatory cytokine production of Caco2 cell monolayers and the resultant changes in barrier function. We hypothesized that even low concentrations of EtOH would cause significant cytokine release and barrier dysfunction in vitro. MATERIALS AND METHODS: Confluent Caco2 cell monolayers were grown in a two-chamber culture system and exposed to varying concentrations of EtOH (0.1%, 0.5%, 1.0%, 1.5%, and 2.0%) with/without Escherichia coli C-25 (EC). Supernatants were collected and TNF and IL6 quantified by ELISA (pg/mL). Monolayer integrity was assessed by apoptosis and permeability measurements. RESULTS: Caco2 production of TNF-alpha increased in a dose-dependent manner when incubated with increasing concentrations of EtoH. A synergistic effect was seen when E. coli was added to the apical chamber. A similar result was seen with the production of IL-6. A dose-dependent effect was also noted with EtOH with or without E. coli on apoptosis and permeability measurements. CONCLUSION: In addition to alterations in gut permeability, increasing concentrations of ethanol have a synergistic effect with E. coli on Caco2 production of proinflammatory cytokines TNF and IL-6. The creation of a proinflammatory cytokine milieu with an altered barrier integrity may be a mechanism by which ethanol may increase septic complications in the injured patient.

Cleavage of SIgA by gram negative respiratory pathogens enhance neutrophil inflammatory potential.

OBJECTIVE: Secretory immunoglobulin A (SIgA), the principle immune defense at respiratory and other mucosal sites in the body, is highly dependant on its molecular structure for effective antibody function. Previous studies have demonstrated that gram-negative but not gram-positive isolates from patients with nosocomial pneumonia have IgA protease activity that contributes to the development of infection. We postulate that SIgA cleavage by bacteria would also affect anti-inflammatory properties of IgA and studied this in vitro. METHODS: Sterile filtrates obtained from Pseudomonas, Acinetobacter, and methicillin resistant Staphylococcus aureus (MRSA) held in culture with SIgA were used to challenge polymorphonuclear neutrophils (PMNs) obtained from healthy volunteers. In a second group of experiments, blood monocytes were incubated with lipopolysaccharide (LPS) or LPS + IgA, and the resulting culture supernatants was used to stimulate PMNs in vitro. RESULTS: LPS-stimulated monocytes increased CD11b expression, O2-generation and elastase release by PMNs. Secretory IgA but not IgG abrogated this response. Cleavage of SIgA by the gram-negative respiratory isolates, Pseudomonas aeruginosa and Acinetobacter baumanii also led to the loss of cellular effector function noted with intact SIgA. Additionally, PMN cytotoxic potential was similar to that noted with PMNs treated with supernatant from LPS-stimulated monocytes. CONCLUSION: IgA cleavage by gram-negative respiratory isolates may lead to the development of pneumonia and the subsequent severity of the infection as a result of uncontrolled inflammatory responses by the host.