Preoperative medically supervised weight loss programs and weight loss outcomes following bariatric surgery - a prospective analysis.

BACKGROUND: Prior to undergoing bariatric surgery, many insurance companies require patients to attend medically supervised weight management visits for 3-6 months to be eligible for surgery. There have been few studies that have looked specifically at the relationship between medically supervised weight management visit attendance and postoperative outcomes, and the current literature reports discrepant findings. OBJECTIVES: This project aimed to better characterize the relationship between preoperative medically supervised weight management visit attendance and postoperative weight loss outcomes by examining weight loss up to 5 years postbariatric surgery, and by stratifying findings according to the type of surgery undergone. SETTING: University Hospital. METHODS: Participants were recruited during presurgical bariatric surgery clinic visits at a bariatric and metabolic weight loss center. As part of standard of care all participants were required to participate in monthly medically supervised weight management visits before surgery. Participants who completed bariatric surgical procedures participated in postsurgical follow-up at 3 weeks, 3 months, 6 months, and then annually for 5 years. Weight outcomes measured were percentage of total weight lost. RESULTS: The results do not indicate a significant association between number of group visits attended and percent total weight loss at 1 month, 3 months, 6 months, 1 year, 2 years, 3 years, 4 years, or 5 years postbariatric surgery. CONCLUSIONS: These data do not suggest a relationship between engagement in a medically supervised weight loss program prior to bariatric surgery and weight loss after surgery in either the short- or the long-term.

Postoperative outcomes for sleeve gastrectomy patients with positive pH-defined GERD.

BACKGROUND: Gastroesophageal reflux disease (GERD) is a possible side effect of sleeve gastrectomy (SG). However, procedure selection for patients with GERD and risk factors for morbidity after bypass surgeries is complex. For patients with a preoperative GERD diagnosis, literature related to worsening postoperative symptoms is discordant. OBJECTIVE: This study evaluated the effects of SG on patients with pre-operative GERD confirmed through pH testing. SETTING: University Hospital, United States. METHODS: This was a single-center case-series. SG patients with preoperative pH testing were compared based on DeMeester scoring. Preoperative demographics, endoscopy results, need for conversion surgery, and changes in gastrointestinal quality of life (GIQLI) scores were compared. Two-sample independent t-tests assuming unequal variances were used for statistical analysis. RESULTS: Twenty SG patients had preoperative pH testing. Nine patients were GERD positive; median DeMeester score 26.7 (22.1-31.15). Eleven patients were GERD negative, with a median DeMeester score of 9.0 (4.5-13.1). The two groups had similar median BMI, preoperative endoscopic findings and use of GERD medications. Concurrent hiatal hernia repair was performed in 22% of GERD positive vs. 36% of GERD negative patients, (p = 0.512). Two patients in the GERD positive cohort required conversion to gastric bypass (22%), while none in the GERD negative cohort did. No significant postoperative differences were noted in GIQLI, heartburn, or regurgitation symptoms. CONCLUSION: Objective pH testing may allow the differentiation of patients who would be higher risk for need for conversion to gastric bypass. For patients with mild symptoms, but negative pH testing, SG may represent a durable option.

The durability of revisional sleeve gastrectomy and Roux-en-Y gastric bypass after previous adjustable gastric band.

BACKGROUND: Patients with adjustable gastric banding (AGB) often require revision to one-stage or two-stage sleeve gastrectomy (SG) or Roux-en-Y gastric bypass (RYGB). OBJECTIVE: To compare the long-term durability of revisional SG and RYGB, in terms of subsequent revision or conversion (RC). METHODS: The New York Statewide Planning and Research Cooperative Systems dataset was queried from 2006 to 2013 for patients who underwent primary SG and RYGB, one-stage, and two-stage conversion from AGB to SG and RYGB. Patients who required RC were identified. A multivariable Cox proportional hazard model was used to compare the RC risk among these groups. RESULTS: 13,749 had primary SG, 621 one-stage, and 321 two-stage AGB to SG. 31,814 had primary RYGB, 555 one-stage, and 248 two-stage AGB to RYGB. The estimated 5-year cumulative RC incidence rate was significantly lower after primary surgery than after prior AGB (one-stage AGB to SG 14.4%, two-stage AGB to SG 11.6%, primary SG 5.2%, one-stage AGB to RYBG 3.4%, two-stage AGB to RYGB 2.9%, and primary RYGB 1.1%, p-value < 0.0001). RYGB and SG did not differ significantly in terms of the elevation effect of one- and two-stage AGB conversion over primary surgeries (RYGB vs SG: one stage vs primary ratio of HR = 0.97, 95% CI = [0.58, 1.63], p-value = 0.9153; two stage vs primary ratio of HR = 1. 02, 95% CI = [0.50, 2.07], p-value = 0.9596). CONCLUSION: RC after AGB to SG or RYGB is more frequent compared to primary surgeries with procedures following AGB to SG being more common than AGB to RYGB. However, that difference was proportionally similar to the RC rate ratio differences noted for primary SG and RYGB.

[S073]-The impact of interval appendectomy timing on follow-up adverse outcomes.

OBJECTIVE: This study aims to compare the timing of interval appendectomy (IA) and its impact on post-operative outcomes. METHODS: A retrospective analysis was performed for adult patients diagnosed with appendicitis between 2006 and 2017. IA was defined as a follow-up appendectomy > 1 week and < 2 years after the initial presentation. Time intervals were divided into 4 groups based on patient quartiles: 1-6 weeks, 7-9 weeks, 10-15 weeks, and > 15 weeks. The primary outcome measure was length of stay (LOS). Secondary outcomes included 30-day readmission and IA post-operative complications. Tertiary outcomes included 30-day mortality and colonoscopy suggesting neoplasm or Inflammatory Bowel Disease. RESULTS: A total of 5069 patients' records whose interval appendectomy fell > 1 week and < 2 years after initial presentation were analyzed. Among them, 1006 (19.85%) underwent an initial percutaneous abscess drainage at diagnosis. The median timing for IA was 9.2 weeks. Patients with IA at 1-6 weeks were more likely to have longer LOS when compared to 7-9 weeks (ratio 1.33, 95% CI 1.2-1.48) and 10-15 weeks (ratio 1.38, 95% CI 1.25-1.52). IA between 7 and 9 weeks (ratio 0.81, 95% CI 0.73-0.89) and 10-15 weeks (ratio 0.78, 95% CI 0.71-0.86) was associated with significantly shorter LOS compared to those receiving the operation after 15 weeks. Further, patients requiring abscess drainage (ratio 1.2, 95% CI 1.13-1.34) or those with comorbidities (ratio 1.51, 95% CI 1.39-1.63) were more likely to have longer LOS at IA. Socioeconomic and demographic differences including Black, Hispanic, and those with Medicare and Medicaid insurance had a greater LOS after their IA. CONCLUSION: LOS remains lowest among patients undergoing IA between 7-9 weeks and 10-15 weeks after initial appendicitis presentation. Patients with lower socioeconomic status or from racial minorities had a longer LOS after IA.

The impact of bariatric surgery on the risk of coronary revascularization.

BACKGROUND: Metabolic surgery is associated with improved cardiovascular risk profile. Randomized and observational studies exploring the impact of bariatric surgery on follow-up coronary revascularization (CR) as a primary endpoint are limited. OBJECTIVES: To identify the impact of metabolic surgery on the risk of follow-up CR, including percutaneous coronary revascularization (PCI) and coronary artery bypass grafting (CABG) SETTING: Stony Brook Department of Surgery, Stony Brook University Hospital, New York, United States. METHODS: A retrospective analysis was performed for patients with obesity between 2006 and September 2015. Patients were divided into those with history of metabolic surgery and those without. Patient were also stratified by bariatric surgery type. All study groups were followed till 2018 and for at least 3 years to monitor the development of the primary endpoint-any CR including PCI or CABG. RESULTS: The study population with obesity was 515,307 patients; 95,901 with history of surgery versus 419,406 matched patients without. A total of 12,873 (13.4%) with surgery and 51,478 (12.27%) without were lost to follow-up by 2018. The group with history of surgery had a reduced risk of future CR (hazard ratio [HR], .46; 95% confidence interval [CI]: .42-.50; P < .0001), PCI (HR, .45; 95% CI: .41-.49; P < .0001) and CABG (HR, .49; 95% CI:.42-.56; P < .0001). In subgroup analysis, laparoscopic adjustable gastric banding compared with Roux-en-Y gastric bypass (RYGB) was associated with higher follow-up CR (HR, 1.34; 95% CI: 1.11-1.63; P < .01) and PCI (HR, 1.34; 95% CI: 1.07-1.68; P < .05). CONCLUSION: Bariatric surgery is associated with reduced risk of future CR, PCI, and CABG. Upon subgroup analysis, RYGB was associated with reduced risk of PCI and CR.

Contact Isolation Precautions in Trauma Patients: An Analysis of Infectious Complications.

BACKGROUND: Victims of traumatic injuries represent a population at risk for a wide variety of complications. Contact isolation (CI) is a set of restrictions designed to help prevent the transmission of medically significant organisms in the healthcare setting. A growing body of literature demonstrates that CI can have significant implications for the individual isolated patient. Our goal was to characterize the use of contact isolation at our Level I trauma center and investigate the association of CI with infectious complications. PATIENTS AND METHODS: An existing trauma database containing data on patients admitted at our Level I trauma center between January 1, 2011 and December 31, 2012, along with their contact isolation status, was queried. Demographics, injuries, and the presence of infections were collected. Diagnosis of pneumonia or UTI was based on clinical documentation in the patient's medical record. A chart review was performed to ascertain the reason for CI including specific organisms. Because of differences in patient demographics between the CI and non-CI groups, linear regression was performed to adjust for the effects of different variables. RESULTS: A total of 4,423 patients were admitted over this period. Of these, 4,318 (97.6%) had complete records and were included in the subsequent analysis. The CI was in place in 249 (5.8%) patients; 4,069 (94.2%) were not isolated. The number who had CI initiated for MRSA nasal colonization was 173 (69.5%). Twenty-two (8.9%) had no reason for CI documented. Pneumonia occurred in 190 (4.4%), 54 (21.7) in the CI group versus 136 (3.3%) in the non-CI group. Urinary tract infection (UTI) was diagnosed in 166 (3.8%), 48 (19.3%) in the CI group versus 118 (2.9%) in the non-CI group. Using logistic regression and excluding patients placed on contact isolation for the development of a new resistant nosocomial infection, CI, Injury Severity Score, gender, length of stay, and mechanical ventilation were identified as common covariates for pneumonia (PNA) and UTI. Chronic obstructive pulmonary disease COPD was specifically identified for PNA. Spinal cord injury, vertebral column injury and pelvic-urogenital injury were also significant for UTI. CONCLUSIONS: The development of pneumonia and UTI in patients with trauma was significantly associated with the use of CI. Because the majority of these patients had CI precautions in place for asymptomatic colonization, the CI provided them no direct benefit. Because the use of CI is associated with multiple negative outcomes, its use in the trauma population needs to be carefully re-evaluated.

Assessing national provision of care: variability in bariatric clinical care pathways.

BACKGROUND: The American Society for Metabolic and Bariatric Surgery (ASMBS) Quality Improvement and Patient Safety (QIPS) Committee hypothesized that collecting and sharing clinical pathways could provide a valuable resource to new and existing bariatric programs. OBJECTIVE: To shed light on the variability in practice patterns across the country by analyzing pathways. SETTING: United States Centers of Excellence METHODS: From June 2014 to April 2015, clinical pathways pertaining to preoperative, intraoperative, and postoperative management of bariatric patients were solicited from the ASMBS executive council (EC), QIPS committee members, and state chapter presidents. Pathways were de-identified and then analyzed based on predetermined metrics pertaining to preoperative, intraoperative, and postoperative care. Concordance and discordance were then analyzed. RESULTS: In total, 31 pathways were collected; response rate was 80% from the EC, 77% from the QIPS committee, and 21% from state chapter presidents. The number of pathways sent in ranged from 1 to 10 with a median of 3 pathways per individual or institution. The majority of pathways centered on perioperative care (80%). Binary assessment (presence or absence) of variables found a high concordance (defined by greater than 65% of pathways accounting for that parameter) in only 6 variables: nutritional evaluation, psychological evaluation, intraoperative venous thromboembolism (VTE) prophylaxis, utilization of antiemetics in the postoperative period, a dedicated pain pathway, and postoperative laboratory evaluation. CONCLUSION: There is considerable national variation in clinical pathways among practicing bariatric surgeons. Most pathways center on Metabolic and Bariatric Surgery Accredited Quality Improvement Program (MBSAQIP) accreditation parameters, patient satisfaction, or Surgical Care Improvement Protocol (SCIP) measures. These pathways provide a path toward standardization of improved care.

Putting the MeaT into TeaM Training: Development, Delivery, and Evaluation of a Surgical Team-Training Workshop.

BACKGROUND: Despite importance to patient care, team training is infrequently used in surgical education. To address this, a workshop was developed by the Association for Surgical Education Simulation Committee to teach team training using high-fidelity patient simulators and the American College of Surgeons-Association of Program Directors in Surgery team-training curriculum. METHODS: Workshops were conducted at 3 national meetings. Participants completed preworkshop and postworkshop questionnaires to define experience, confidence in using simulation, intention to implement, as well as workshop content quality. The course consisted of (A) a didactic review of Preparation, Implementation, and Debriefing and (B) facilitated small group simulation sessions followed by debriefings. RESULTS: Of 78 participants, 51 completed the workshops. Overall, 65% indicated that residents at their institutions used patient simulation, but only 33% used the American College of Surgeons-the Association of Program Directors in Surgery team-training modules. The workshop increased confidence to implement simulation team training (3.4 ± 1.3 vs 4.5 ± 0.9). Quality and importance were rated highly (5.4 ± 00.6, highest score = 6). CONCLUSIONS: Preparation for simulation-based team training is possible in this workshop setting, although the effect on actual implementation remains to be determined.

Oxidative Stress Increases Surface Toll-Like Receptor 4 Expression in Murine Macrophages Via Ceramide Generation.

Multiorgan failure is a major cause of late mortality following trauma. Oxidative stress generated during shock/resuscitation contributes to tissue injury by priming the immune system for an exaggerated response to subsequent inflammatory stimuli, such as lipopolysaccharide (LPS). We recently reported that oxidative stress causes rapid recruitment of the LPS receptor Toll-like receptor 4 (TLR4) to membrane lipid rafts, thus increasing LPS responsiveness and cellular priming. We hypothesized that activation of Src family kinases by oxidants might contribute to these events. We utilized microscopy, flow cytometry, Western blotting, and thin-layer chromatography methods. Using hydrogen peroxide in vitro and hemorrhagic shock/resuscitation in vivo, oxidant-induced TLR4 translocation in macrophages occurred in an Src-dependent manner. Approaches supporting this conclusion included pharmacologic inhibition of the Src family kinases by PP2, Src inhibition by a molecular approach of cell transfection with Csk, and genetic inhibition of all Src kinases relevant to the monocyte/macrophage lineage in hckfgrlyn triple knockout mice. To evaluate the upstream molecules involved in Src activation, we evaluated the ability of oxidative stress to activate the bioactive lipid molecule ceramide. Oxidants induced ceramide generation in macrophages both in vitro and in vivo, an effect that appears to be due to activation of the acid sphingomyelinase. Using pharmacological approaches, ceramide was shown to be both necessary and sufficient to mediate TLR4 translocation to the plasma membrane in an Src-dependent manner. This study identifies a hierarchy of signaling molecules following oxidative stress that might represent novel targets for therapy in critical illness and organ injury.

Seasoned surgeons assessed in a laparoscopic surgical crisis.

OBJECTIVE: Maintenance of certification is a relatively new concept in the United States, and there is no mandatory retirement for surgeons. Our aim was to compare technical and team performance of surgeons of different ages in a simulated laparoscopic surgical crisis and validate a potential recredentialing tool for surgeons. METHODS: Using a single-blinded protocol, the performance of six "Seasoned" surgeons >55 years (mean 64, range 55-83) was compared to six "control" surgeons <55 years (mean 46, range 34-53) in a simulation. Surgical teams established pneumoperitoneum, trocar access, and managed intraabdominal hemorrhage in a simulated laparoscopic cholecystectomy while videotaped as part of an IRB protocol. Surgeons' performance was scored using validated technical and team performance scales. RESULTS: All of the "seasoned" surgeons relegated the use of unfamiliar technology to their assistants. All control surgeons achieved intraabdominal pneumoperitoneum themselves. Mean blood loss for seasoned surgeons and control surgeons was 2,555 versus 2,725 ml (NS), respectively. After recognition of bleeding in the unstable patient, senior surgeons converted to an urgent laparotomy case after 2.4 vs. 3.3 min for control group (NS). No difference was observed in overall technical and team abilities (p = NS). On debriefing, 85% of surgeons recommended simulation for training and recertification. CONCLUSIONS: Seasoned surgeons can use their assistant surgeon well to assure a safe and effective operation. Mandatory operating room retirement based on age may be arbitrary and should be replaced by performance measures. Simulation may prove a valuable tool for self -assessment and recredentialing.

Integrating simulation in surgery as a teaching tool and credentialing standard.

The time-honored training methods of surgery are rapidly being replaced with new teaching tools that are being integrated into residency and recredentialing standards. Numerous factors including societal, professional, and legal have all forced surgical training programs to seek alternative methods of training residents. Learning theories that have provided the basis for open surgical skills training have been modified and culminated in the theory of automaticity and the "pretrained" laparoscopic novice. A vast array of simulators exist for training, ranging from inanimate video trainers, human patient simulators, to more recently virtual reality (VR) computer-based trainers. Currently, inanimate trainers are deployed widely throughout surgical training programs and serve as the primary platform for laparoscopic skills training. As technology evolves, VR systems have become available, allowing for more complex skills training with realistic computer-generated anatomic structures. Using the theories of crisis management and crew resource management, simulation is moving from simple skills training to whole-team training in mock operating room environments. Looking to the near future, medical training will continue to evolve to meet the changing demands of society and professional responsibility to ensure patient safety. With the advent of accredited skills-training centers endorsed by the American College of Surgeons, simulation will be the catalyst for these continuing changes.

Simulated laparoscopic operating room crisis: An approach to enhance the surgical team performance.

OBJECTIVE: Diminishing human error and improving patient outcomes is the goal of task training and simulation experience. The fundamentals of laparoscopic surgery (FLS) is a validated tool to assess technical laparoscopic skills. We hypothesize that performance in a crisis depends on technical skills and team performance. The aim of this study was to develop and validate a high-fidelity simulation model of a laparoscopic crisis scenario in a mock endosuite environment. METHODS: To establish the feasibility of the model as well as its face and construct validity, the scenario evaluated the performances of FLS-certified surgeon experts (n = 5) and non-FLS certified novices (n = 5) during a laparoscopic crisis scenario, in a mock endosuite, on a simulated abdomen. Likert scale questionnaires were used for validity assessments. Groups were compared using previously validated rating scales on technical and nontechnical performance. Objective outcome measures assessed were: time to diagnose bleeding (TD), time to inform the team to convert (TT), and time to conversion to open (TC). SAS software was used for statistical analysis. RESULTS: Median scores for face validity were 4.29, 4.43, 4.71 (maximum 5) for the FLS, non-FLS, and nursing groups, respectively, with an inter-rater reliability of 93%. Although no difference was observed in Veress needle safety and laparoscopic equipment set up, there was a significant difference between the two groups in their overall technical and nontechnical abilities (p < 0.05), specifically in identifying bleeding, controlling bleeding, team communication, and team skills. There was a trend towards a difference between the two groups for TD, TT, and TC. While experts controlled bleeding in a shorter time, they persisted longer laparoscopically. CONCLUSIONS: Our evidence suggests that face and construct validity are established for a laparoscopic crisis simulation in a mock endosuite. Technical and nontechnical performance discrimination is observed between novices and experts. This innovative multidisciplinary simulation aims at improving error/problem recognition and timely initiation of appropriate and safe responses by surgical teams.

Financial impact of obesity and bariatric surgery.

Obesity constitutes a major health problem with serious social and economic consequences worldwide. In North America, nearly one third of the population is obese, and this figure includes children and adolescents who are likely to become obese adults. Obesity carries a great financial impact on society; consequently, treating morbidly obese patients with surgery may offer substantial economic savings. This article summarizes the financial burdens of obesity and the economics of treating obesity in North America. It addresses the medical effectiveness and cost-effectiveness of bariatric surgery and the new regulations and accreditations for bariatric surgery programs.

Oxidative stress generated by hemorrhagic shock recruits Toll-like receptor 4 to the plasma membrane in macrophages.

Oxidative stress generated by ischemia/reperfusion is known to prime inflammatory cells for increased responsiveness to subsequent stimuli, such as lipopolysaccharide (LPS). The mechanism(s) underlying this effect remains poorly elucidated. These studies show that alveolar macrophages recovered from rodents subjected to hemorrhagic shock/resuscitation expressed increased surface levels of Toll-like receptor 4 (TLR4), an effect inhibited by adding the antioxidant N-acetylcysteine to the resuscitation fluid. Consistent with a role for oxidative stress in this effect, in vitro H2O2 treatment of RAW 264.7 macrophages similarly caused an increase in surface TLR4. The H2O2-induced increase in surface TLR4 was prevented by depleting intracellular calcium or disrupting the cytoskeleton, suggesting the involvement of receptor exocytosis. Further, fluorescent resonance energy transfer between TLR4 and the raft marker GM1 as well as biochemical analysis of the raft components demonstrated that oxidative stress redistributes TLR4 to lipid rafts in the plasma membrane. Preventing the oxidant-induced movement of TLR4 to lipid rafts using methyl-beta-cyclodextrin precluded the increased responsiveness of cells to LPS after H2O2 treatment. Collectively, these studies suggest a novel mechanism whereby oxidative stress might prime the responsiveness of cells of the innate immune system.

Impaired induction of IL-10 expression in the lung following hemorrhagic shock.

The balance between pro- and anti-inflammatory cytokines is considered to be an important determinant of the magnitude of inflammation in a number of disease states. We previously showed that resuscitated hemorrhagic shock augmented LPS-induced release of proinflammatory molecules by alveolar macrophages (AM). In the present studies, we evaluated the expression and regulation of the counter inflammatory cytokine IL-10 in the lung using this model. We hypothesized that impaired up-regulation of IL-10 in shock/resuscitated animals might serve as a mechanism contributing to accentuated lung inflammation. In a rodent model, animals exposed to LPS alone exhibited enhanced IL-10 mRNA levels in lung tissue as well as in AM, but antecedent shock/resuscitation delayed and attenuated the LPS-induced IL-10 mRNA levels. The ability of shock to attenuate LPS-stimulated IL-10 was also seen in the protein levels. This effect correlated with an augmented expression of cytokine-induced neutrophil chemoattractant (CINC) mRNA. Shock/resuscitated animals given exogenous IL-10 had reduced proinflammatory response, as shown by decreased expression of CINC mRNA and decreased neutrophil sequestration in the lung. Shock/resuscitation plus LPS markedly reduced the transcription rate of IL-10 mRNA compared to LPS alone but did not affect IL-10 mRNA stability. Reduced IL-10 transcription was not caused solely by impaired nuclear translocation of STAT3 and Sp1/Sp3 transcription factors because LPS-induced nuclear translocation of these factors was augmented by antecedent shock. Considered together, these findings show that shock/resuscitation suppresses LPS-induced IL-10 expression by AM in the lung by inhibiting IL-10 gene transcription. Failed up-regulation of counter inflammatory cytokines may contribute to augmented organ dysfunction in trauma patients.

The role of the Src family of tyrosine kinases after oxidant-induced lung injury in vivo.

BACKGROUND: Patients sustaining major trauma are predisposed to the development of organ dysfunction. We have shown that oxidant stress generated by hemorrhagic shock/resuscitation (S/R) in rodents increases lipopolysaccharide (LPS)-induced lung injury and translocation of nuclear factor kappa B (NF-kappaB) in alveolar macrophages (AMs). In addition, using a cellular model, we have shown that priming with oxidants reprograms LPS signaling through an Src-dependent pathway. In the present studies, we hypothesize that oxidant priming by S/R in vivo involves Src family kinases. METHODS: Rats were bled to a mean arterial pressure of 40 mmHg and maintained for 1 hour, then resuscitated with shed blood and equal volume of Ringer's lactate. In some studies, animals received the antioxidant NAC (0.5 g/kg) or a Src family inhibitor, PP2 (0.1 or 0.2 mg/kg), before resuscitation. LPS was given intratracheally (30 mg/kg) for 4 hours. AMs were lavaged, and total cell counts were determined. AMs were also obtained at end resuscitation and exposed to LPS (0.1 microg/mL) from 0 to 60 minutes. Activation of Hck, an Src family kinase, was analyzed by Western blot using a phosphospecific antibody. Nuclear extracts were obtained to examine NF-kappaB translocation. RESULTS: S/R caused a rise in Src family activity compared with sham animals as shown by the phosphorylation of Hck. This was prevented by treating the animals during resuscitation with NAC. The LPS-induced NF-kappaB translocation in AMs after shock/resuscitation was 3-fold higher than in sham AMs treated with LPS. This augmented translocation was prevented by pretreating the animals with PP2 before resuscitation. In a parallel fashion, PP2 pretreatment reduced the absolute lung neutrophil sequestration. CONCLUSION: Oxidant stress generated during S/R in vivo causes Src family kinase activation in AMs. Inhibition of Src activation by PP2 attenuates AM priming for increased LPS responsiveness after hemorrhagic shock and causes a modest reduction in lung injury. Inhibition of the Src family kinases may be a novel approach for the treatment of lung injury after trauma.

Twenty-five percent albumin prevents lung injury following shock/resuscitation.

OBJECTIVE: To evaluate novel indications for the use of human albumin solutions in the prevention and treatment of acute lung injury following shock/resuscitation and to test the hypothesis that 25% human albumin is an effective resuscitation fluid as well as an immunomodulatory agent protective against lung injury in our model. DESIGN: A previously developed rodent model of acute lung injury in which resuscitated shock primes for increased lung injury in response to a small dose of intratracheal lipopolysaccharide. SETTING: University-affiliated hospital. SUBJECTS: Sprague Dawley rats weighing 300-350 g. INTERVENTIONS: Animals were bled to a mean arterial pressure of 40 mm Hg and maintained in a shock phase for 1 hr. Animals then were resuscitated by transfusion of the shed blood plus an equal volume of Ringer's lactate or their shed blood plus 3 mL/kg volume of 25% albumin or their shed blood plus 15 mL/kg of 5% human albumin over a period of 2 hrs. To test for the possible role of 25% albumin as an antioxidant, we also performed resuscitation with Ringer's lactate supplemented with N-acetylcysteine or 25% albumin depleted of its antioxidant properties by N-ethylmaleimide. Mean arterial pressure was monitored continuously. One hour after resuscitation, 100 microg of lipopolysaccharide in 200 microL of saline was administered intratracheally. MEASUREMENTS AND MAIN RESULTS: Resuscitation with 25% albumin significantly reduced transpulmonary protein flux, bronchoalveolar lavage fluid neutrophil counts, and the degree of histopathological injury compared with resuscitation with Ringer's lactate or 5% albumin. To delineate the underlying mechanism of this beneficial effect, the production of cytokine-induced neutrophil chemoattractant as well as nuclear translocation of its critical transcription factor nuclear factor-kappaB was measured. Both cytokine-induced neutrophil chemoattractant messenger RNA concentrations and nuclear factor-kappaB translocation were diminished following 25% albumin resuscitation. Furthermore, 25% albumin significantly decreased lipid peroxidation in plasma as measured by 8-isoprostane concentrations. N-ethylmaleimide modified 25% albumin, possessing lesser antioxidant activity, exhibited an attenuated protection from lung injury. CONCLUSIONS: Resuscitation with 25% albumin attenuates lung injury in this rat model. The beneficial effect was due to reduced neutrophil sequestration. The antioxidant properties of the 25% albumin preparation appeared to be partially responsible for the effects observed. These studies suggest a novel role for 25% albumin as an anti-inflammatory agent in neutrophil-mediated diseases, such as acute respiratory distress syndrome.

Oxidative stress reprograms lipopolysaccharide signaling via Src kinase-dependent pathway in RAW 264.7 macrophage cell line.

Oxidative stress generated during ischemia/reperfusion injury has been shown to augment cellular responsiveness. Whereas oxidants are themselves known to induce several intracellular signaling cascades, their effect on signaling pathways initiated by other inflammatory stimuli remains poorly elucidated. Previous work has suggested that oxidants are able to prime alveolar macrophages for increased NF-kappa B translocation in response to treatment with lipopolysaccharide (LPS). Because oxidants are known to stimulate the Src family of tyrosine kinases, we hypothesized that the oxidants might contribute to augmented NF-kappa B translocation by LPS via the involvement of Src family kinases. To model macrophage priming in vitro, the murine macrophage cell line, RAW 264.7, was first incubated with various oxidants and then exposed to low dose LPS. These studies show that oxidant stress is able to augment macrophage responsiveness to LPS as evidenced by earlier and increased NF-kappa B translocation. Inhibition of the Src family kinases by either pharmacological inhibition using PP2 or through a molecular approach by cell transfection with Csk was found to prevent the augmented LPS-induced NF-kappa B translocation caused by oxidants. Interestingly, while Src kinase inhibition was able to prevent the LPS-induced NF-kappa B translocation in oxidant-treated macrophages, this strategy had no effect on NF-kappa B translocation caused by LPS in the absence of oxidants. These findings suggested that oxidative stress might divert LPS signaling along an alternative signaling pathway. Further studies demonstrated that the Src-dependent pathway induced by oxidant pretreatment involved the activation of phosphatidylinositol 3-kinase. Involvement of this pathway appeared to be independent of traditional LPS signaling. Together, these studies provide a novel potential mechanism whereby oxidants might prime alveolar macrophages for altered responsiveness to subsequent inflammatory stimuli and suggest different cellular targets for immunomodulation following ischemia/reperfusion.

Oxidant-induced priming of the macrophage involves activation of p38 mitogen-activated protein kinase through an Src-dependent pathway.

BACKGROUND: Resuscitated hemorrhagic shock predisposes patients to the development of organ dysfunction, particularly to lung injury. Ischemia/reperfusion during shock is believed to prime the immune system for an exaggerated inflammatory response to a second delayed stimulus. We previously reported an in vitro model of oxidant-induced priming of the macrophage to lipopolysaccharide (LPS) involves the Src family of tyrosine kinases. Because the Src family has been shown to activate the p38 mitogen-activated protein kinase (MAPK) pathway, we hypothesize that LPS signaling after oxidant stress involves the p38 pathway and is activated by Src kinases. METHODS: The murine macrophage cell line, Raw 264.7, was first incubated with H(2)O(2) 100 micromol/L for 1 hour and then with low dose LPS 0.01 microg/mL for 5 to 45 minutes. In a separate experiment, the cells were pretreated with PP2 or SB203580, a specific inhibitor of the Src family and p38 respectively. The phosphorylation of p38, representative of its activation, was assessed in whole cell lysates by use of Western blotting. NF-kappaB translocation was detected by immunofluorescence with anti-p65 antibody. RESULTS: There is a time dependent earlier activation of p38 by oxidant stress. H(2)O(2) augmented the LPS-induced p38 phosphorylation. The Src inhibitor, PP2, prevented only the LPS-induced earlier phosphorylation after oxidant stress and had no effect on LPS activation of p38 alone. The p38 inhibitor had no effect in preventing NF-kappaB translocation in either the LPS- or H(2)O(2)/LPS-exposed cells. CONCLUSIONS: Oxidant stress generated during global ischemia/reperfusion activates p38 MAPK in an Src-dependent manner. Oxidants seem to alter the LPS-induced activation of p38. P38 does not seem to have a direct role in leading to oxidant-induced NF-kappaB translocation but may affect other oxidant-induced transcription factors. This altered pathway provides an alternative avenue to target therapy during the oxidant-induced priming of the macrophage induced by trauma resuscitation.