Paul E. Bankey

Genomic responses in mouse models poorly mimic human inflammatory diseases

A cornerstone of modern biomedical research is the use of mouse models to explore basic pathophysiological mechanisms, evaluate new therapeutic approaches, and make go or no-go decisions to carry new drug candidates forward into clinical trials. Systematic studies evaluating how well murine models mimic human inflammatory diseases are nonexistent. Here, we show that, although acute inflammatory stresses from different etiologies result in highly similar genomic responses in humans, the responses in corresponding mouse models correlate poorly with the human conditions and also, one another. Among genes changed significantly in humans, the murine orthologs are close to random in matching their human counterparts (e.g., R2 between 0.0 and 0.1). In addition to improvements in the current animal model systems, our study supports higher priority for translational medical research to focus on the more complex human conditions rather than relying on mouse models to study human inflammatory diseases.

Prospective Study of Blunt Aortic Injury: Multicenter Trial of the American Association for the Surgery of Trauma

BACKGROUND Blunt aortic injury is a major cause of death from blunt trauma. Evolution of diagnostic techniques and methods of operative repair have altered the management and posed new questions in recent years. METHODS This study was a prospectively conducted multi-center trial involving 50 trauma centers in North America under the direction of the Multi-institutional Trial Committee of the American Association for the Surgery of Trauma. RESULTS There were 274 blunt aortic injury cases studied over 2.5 years, of which 81% were caused by automobile crashes. Chest computed tomography and transesophageal echocardiography were applied in 88 and 30 cases, respectively, and were 75 and 80% diagnostic, respectively. Two hundred seven stable patients underwent planned thoracotomy and repair. Clamp and sew technique was used in 73 (35%) and bypass techniques in 134 (65%). Overall mortality was 31%, with 63% of deaths being attributable to aortic rupture; mortality was not affected by method of repair. Paraplegia occurred postoperatively in 8.7%. Logistic regression analysis demonstrated clamp and sew (p = 0.002) and aortic cross clamp time of > or = 30 minutes (p = 0.01) to be associated with development of postoperative paraplegia. CONCLUSIONS Rupture after hospital admission remains a major problem. Although newer diagnostic techniques are being applied, at this time aortography remains the diagnostic standard. Aortic cross clamp time beyond 30 minutes was associated with paraplegia; bypass techniques, which provide distal aortic perfusion, produced significantly lower paraplegia rates than the clamp and sew approach.

A genomic storm in critically injured humans

Critical injury in humans induces a genomic storm with simultaneous changes in expression of innate and adaptive immunity genes.

Quantitative proteome analysis of human plasma following in vivo lypopolysaccharide administration using 16O/18O labeling and the accurate mass and time tag approach

Identification of novel diagnostic or therapeutic biomarkers from human blood plasma would benefit significantly from quantitative measurements of the proteome constituents over a range of physiological conditions. Herein we describe an initial demonstration of proteome-wide quantitative analysis of human plasma. The approach utilizes postdigestion trypsin-catalyzed 16O/18O peptide labeling, two-dimensional LC-FTICR mass spectrometry, and the accurate mass and time (AMT) tag strategy to identify and quantify peptides/proteins from complex samples. A peptide accurate mass and LC elution time AMT tag data base was initially generated using MS/MS following extensive multidimensional LC separations to provide the basis for subsequent peptide identifications. The AMT tag data base contains >8,000 putative identified peptides, providing 938 confident plasma protein identifications. The quantitative approach was applied without depletion of high abundance proteins for comparative analyses of plasma samples from an individual prior to and 9 h after lipopolysaccharide (LPS) administration. Accurate quantification of changes in protein abundance was demonstrated by both 1:1 labeling of control plasma and the comparison between the plasma samples following LPS administration. A total of 429 distinct plasma proteins were quantified from the comparative analyses, and the protein abundances for 25 proteins, including several known inflammatory response mediators, were observed to change significantly following LPS administration.

High Dynamic Range Characterization of the Trauma Patient Plasma Proteome

Although human plasma represents an attractive sample for disease biomarker discovery, the extreme complexity and large dynamic range in protein concentrations present significant challenges for characterization, candidate biomarker discovery, and validation. Herein we describe a strategy that combines immunoaffinity subtraction and subsequent chemical fractionation based on cysteinyl peptide and N-glycopeptide captures with two-dimensional LC-MS/MS to increase the dynamic range of analysis for plasma. Application of this “divide-and-conquer” strategy to trauma patient plasma significantly improved the overall dynamic range of detection and resulted in confident identification of 22,267 unique peptides from four different peptide populations (cysteinyl peptides, non-cysteinyl peptides, N-glycopeptides, and non-glycopeptides) that covered 3654 different proteins with 1494 proteins identified by multiple peptides. Numerous low abundance proteins were identified, exemplified by 78 “classic” cytokines and cytokine receptors and by 136 human cell differentiation molecules. Additionally a total of 2910 different N-glycopeptides that correspond to 662 N-glycoproteins and 1553 N-glycosylation sites were identified. A panel of the proteins identified in this study is known to be involved in inflammation and immune responses. This study established an extensive reference protein database for trauma patients that provides a foundation for future high throughput quantitative plasma proteomic studies designed to elucidate the mechanisms that underlie systemic inflammatory responses.

Temporal Bone Fractures: Otic Capsule Sparing versus Otic Capsule Violating Clinical and Radiographic Considerations

OBJECTIVE To assess the practicality and utility of the traditional classification system for temporal bone fracture (transverse vs. longitudinal) in the modern Level I trauma setting and to determine whether a newer system of designation (otic capsule sparing vs. otic capsule violating fracture) is practical from a clinical and radiographic standpoint. METHODS The University of Massachusetts Medical Center Trauma Registry was reviewed for the years 1995 to 1997. Patients identified as sustaining closed head injury were reviewed for basilar skull fracture and temporal bone fracture. Clinical and radiographic records were evaluated by using the two classification schemes. RESULTS A total of 2,977 patients were treated at the trauma center during this time. Ninety (3%) patients sustained a temporal bone fracture. The classic characterization of transverse versus longitudinal fracture (20% vs. 80%, respectively) was unable to be determined in this group; therefore, clinical correlation to complications using that paradigm was not possible. By using the otic capsule violating versus sparing designation, an important difference in clinical sequelae and intracranial complications became apparent. Compared with otic capsule sparing fractures, patients with otic capsule violating fractures were approximately two times more likely to develop facial paralysis, four times more likely to develop CSF leak, and seven times more likely to experience profound hearing loss, as well as more likely to sustain intracranial complications including epidural hematoma and subarachnoid hemorrhage. CONCLUSION The use of a classification system for temporal bone fractures that emphasizes violation or lack of violation of the otic capsule seems to offer the advantage of radiographic utility and stratification of clinical severity, including severity of Glasgow Coma Scale scores and intracranial complications such as subarachnoid hemorrhage and epidural hematoma.

Ground level falls are associated with significant mortality in elderly patients

BACKGROUND Falls from height are considered to be high risk for multisystem injury. Ground-level falls (GLF) are often deemed a low-energy mechanism of injury (MOI) and not a recommended triage criterion for trauma team activation. We hypothesize that in elderly patients, a GLF may represent a high-risk group for injury and concurrent comorbidities that warrant trauma service evaluation and should be triaged appropriately. METHODS This is a retrospective study based on the National Trauma Data Bank. All patients with MOI consistent with GLF were identified. Demographics, type and severity of injuries, and outcomes were analyzed. RESULTS We identified 57,302 patients with GLF. The group had 34% men, with mean age of 68 years ± 17 years and injury severity score of 8 ± 5. Overall mortality was 3.2%. There were 32,320 elderly patients (older than 70 years). The mortality in the elderly was significantly higher than the nonelderly (4.4% vs. 1.6%, p < 0.0001). The elderly were more likely to sustain long-bone fracture (54.5% vs. 35.9%, p < 0.0001), pelvic fracture (7.6% vs. 2.4%, p < 0.0001), and intracranial injury (10.6% vs. 8.7%, p<0.0001). Multivariate analysis showed that Glasgow Coma Scale (GCS) score <15 (odds ratio, 4.98) and older than 70 years (odds ratio, 2.75) were significant predictors of mortality inpatients after GLF. CONCLUSIONS Patients older than 70 years and with GCS score <15 represent a group with significant inhospital mortality.

Helicopters and the civilian trauma system: national utilization patterns demonstrate improved outcomes after traumatic injury.

BACKGROUND The role of helicopter transport (HT) in civilian trauma care remains controversial. The objective of this study was to compare patient outcomes after transport from the scene of injury by HT and ground transport using a national patient sample. METHODS Patients transported from the scene of injury by HT or ground transport in 2007 were identified using the National Trauma Databank version 8. Injury severity, utilization of hospital resources, and outcomes were compared. Stepwise logistic regression was used to determine whether transport modality was a predictor of survival or discharge to home after adjusting for covariates. RESULTS There were 258,387 patients transported by helicopter (16%) or ground (84%). Mean Injury Severity Score was higher in HT patients (15.9 ± 12.3 vs. 10.2 ± 9.5, p < 0.01), as was the percentage of patients with Injury Severity Score >15 (42.6% vs. 20.8%; odds ratio [OR], 2.83; 95% confidence interval [CI], 2.76-2.89). HT patients had higher rates of intensive care unit admission (43.5% vs. 22.9%; OR, 2.58; 95% CI, 2.53-2.64) and mechanical ventilation (20.8% vs. 7.4%; OR, 3.30; 95% CI, 3.21-3.40). HT was a predictor of survival (OR, 1.22; 95% CI, 1.17-1.27) and discharge to home (OR, 1.05; 95% CI, 1.02-1.07) after adjustment for covariates. CONCLUSIONS Trauma patients transported by helicopter were more severely injured, had longer transport times, and required more hospital resources than those transported by ground. Despite this, HT patients were more likely to survive and were more likely to be discharged home after treatment when compared with those transported by ground. Despite concerns regarding helicopter utilization in the civilian setting, this study shows that HT has merit and impacts outcome.

Cell-specific expression and pathway analyses reveal alterations in trauma-related human T cell and monocyte pathways.

Monitoring genome-wide, cell-specific responses to human disease, although challenging, holds great promise for the future of medicine. Patients with injuries severe enough to develop multiple organ dysfunction syndrome have multiple immune derangements, including T cell apoptosis and anergy combined with depressed monocyte antigen presentation. Genome-wide expression analysis of highly enriched circulating leukocyte subpopulations, combined with cell-specific pathway analyses, offers an opportunity to discover leukocyte regulatory networks in critically injured patients. Severe injury induced significant changes in T cell (5,693 genes), monocyte (2,801 genes), and total leukocyte (3,437 genes) transcriptomes, with only 911 of these genes common to all three cell populations (12%). T cell-specific pathway analyses identified increased gene expression of several inhibitory receptors (PD-1, CD152, NRP-1, and Lag3) and concomitant decreases in stimulatory receptors (CD28, CD4, and IL-2Rα). Functional analysis of T cells and monocytes confirmed reduced T cell proliferation and increased cell surface expression of negative signaling receptors paired with decreased monocyte costimulation ligands. Thus, genome-wide expression from highly enriched cell populations combined with knowledge-based pathway analyses leads to the identification of regulatory networks differentially expressed in injured patients. Importantly, application of cell separation, genome-wide expression, and cell-specific pathway analyses can be used to discover pathway alterations in human disease.

Enhancing hepatocyte adhesion by pulsed plasma deposition and polyethylene glycol coupling.

Decreased hepatocyte adhesion to polymeric constructs limits the function of tissue engineered hepatic assist devices. We grafted adhesion peptides (RGD and YIGSR) to polycaprolactone (PCL) and poly-L-lactic acid (PLLA) in order to mimic the in vivo extracellular matrix and thus enhance hepatocyte adhesion. Peptide grafting was done by a novel technique in which polyethylene glycol (PEG)-adhesion peptide was linked to allyl-amine coated on the surface of PCL and PLLA by pulsed plasma deposition (PPD). Peptide grafting density, quantified by radio-iodinated tyrosine in YIGSR, was 158 fmol/cm(2) on PLLA and 425 fmol/cm(2) on PCL surfaces. The adhesion of hepatocytes was determined by plating 250,000 hepatocytes/well (test substrates were coated on 12 well plates) and quantifying the percentage of adhered cells after 6 h by MTT assay. Adhesion on PCL surfaces was significantly enhanced (p < 0.05) by both YIGSR (percentage of adhered cells = 53 +/- 7%) and RGD (53 +/- 12%) when compared to control surfaces (31 +/- 8%). Hepatocyte adhesion on PLLA was significantly (p < 0.05) enhanced on PLLA-PEG-RGD surfaces (76 +/- 14%) compared to control surfaces (42 +/- 19%) and more (68 +/- 25%) but not statistically significant (p = 0.15) on PLLA-PEG-YIGSR surfaces compared to control surfaces. These results indicate that hepatocyte adhesion to PCL and PLLA based polymeric surfaces can be enhanced by a novel adhesion peptide grafting technique using pulsed plasma deposition and PEG cross-linking.