Identification and neuroprotective properties of NA-184, a calpain-2 inhibitor

Our laboratory has shown that calpain-2 activation in the brain following acute injury is directly related to neuronal damage and the long-term functional consequences of the injury, while calpain-1 activation is generally neuroprotective and calpain-1 deletion exacerbates neuronal injury. We have also shown that a relatively selective calpain-2 inhibitor, referred to as C2I, enhanced long-term potentiation and learning and memory, and provided neuroprotection in the controlled cortical impact (CCI) model of traumatic brain injury (TBI) in mice. Using molecular dynamic simulation and Site Identification by Ligand Competitive Saturation (SILCS) software, we generated about 130 analogs of C2I and tested them in a number of in vitro and in vivo assays. These led to the identification of two interesting compounds, NA-112 and NA-184. Further analyses indicated that NA-184, (S)-2-(3-benzylureido)-N-((R,S)-1-((3-chloro-2-methoxybenzyl)amino)-1,2-dioxopentan-3-yl)-4-methylpentanamide, selectively and dose-dependent inhibited calpain-2 activity without evident inhibition of calpain-1 at the tested concentrations in mouse brain tissues and human cell lines. Like NA-112, NA-184 inhibited TBI-induced calpain-2 activation and cell death in mice and rats, both male and females. Pharmacokinetic and pharmacodynamic analyses indicated that NA-184 exhibited properties, including stability in plasma and liver and blood-brain barrier permeability, that make it a good clinical candidate for the treatment of TBI.

Weight-based enoxaparin thromboprophylaxis in young trauma patients: analysis of the CLOTT-1 registry

Introduction

Optimal venous thromboembolism (VTE) enoxaparin prophylaxis dosing remains elusive. Weight-based (WB) dosing safely increases anti-factor Xa levels without the need for routine monitoring but it is unclear if it leads to lower VTE risk. We hypothesized that WB dosing would decrease VTE risk compared with standard fixed dosing (SFD).

Methods

Patients from the prospective, observational CLOTT-1 registry receiving prophylactic enoxaparin (n=5539) were categorized as WB (0.45-0.55 mg/kg two times per day) or SFD (30 mg two times per day, 40 mg once a day). Multivariate logistic regression was used to generate a predicted probability of VTE for WB and SFD patients.

Results

Of 4360 patients analyzed, 1065 (24.4%) were WB and 3295 (75.6%) were SFD. WB patients were younger, female, more severely injured, and underwent major operation or major venous repair at a higher rate than individuals in the SFD group. Obesity was more common among the SFD group. Unadjusted VTE rates were comparable (WB 3.1% vs. SFD 3.9%; p=0.221). Early prophylaxis was associated with lower VTE rate (1.4% vs. 5.0%; p=0.001) and deep vein thrombosis (0.9% vs. 4.4%; p<0.001), but not pulmonary embolism (0.7% vs. 1.4%; p=0.259). After adjustment, VTE incidence did not differ by dosing strategy (adjusted OR (aOR) 0.75, 95% CI 0.38 to 1.48); however, early administration was associated with a significant reduction in VTE (aOR 0.47, 95% CI 0.30 to 0.74).

Conclusion

In young trauma patients, WB prophylaxis is not associated with reduced VTE rate when compared with SFD. The timing of the initiation of chemoprophylaxis may be more important than the dosing strategy. Further studies need to evaluate these findings across a wider age and comorbidity spectrum.

Level of evidence

Level IV, therapeutic/care management.

Differentiation of hypervirulent and classical Klebsiella pneumoniae with acquired drug resistance

Distinguishing hypervirulent (hvKp) from classical Klebsiella pneumoniae (cKp) strains is important for clinical care, surveillance, and research. Some combinations of iucA, iroB, peg-344, rmpA, and rmpA2 are most commonly used, but it is unclear what combination of genotypic or phenotypic markers (e.g., siderophore concentration, mucoviscosity) most accurately predicts the hypervirulent phenotype. Furthermore, acquisition of antimicrobial resistance may affect virulence and confound identification. Therefore, 49 K. pneumoniae strains that possessed some combinations of iucA, iroB, peg-344, rmpA, and rmpA2 and had acquired resistance were assembled and categorized as hypervirulent hvKp (hvKp) (N = 16) or cKp (N = 33) via a murine infection model. Biomarker number, siderophore production, mucoviscosity, virulence plasmid's Mash/Jaccard distances to the canonical pLVPK, and Kleborate virulence score were measured and evaluated to accurately differentiate these pathotypes. Both stepwise logistic regression and a CART model were used to determine which variable was most predictive of the strain cohorts. The biomarker count alone was the strongest predictor for both analyses. For logistic regression, the area under the curve for biomarker count was 0.962 (P = 0.004). The CART model generated the classification rule that a biomarker count = 5 would classify the strain as hvKP, resulting in a sensitivity for predicting hvKP of 94% (15/16), a specificity of 94% (31/33), and an overall accuracy of 94% (46/49). Although a count of ≥4 was 100% (16/16) sensitive for predicting hvKP, the specificity and accuracy decreased to 76% (25/33) and 84% (41/49), respectively. These findings can be used to inform the identification of hvKp.IMPORTANCEHypervirulent Klebsiella pneumoniae (hvKp) is a concerning pathogen that can cause life-threatening infections in otherwise healthy individuals. Importantly, although strains of hvKp have been acquiring antimicrobial resistance, the effect on virulence is unclear. Therefore, it is of critical importance to determine whether a given antimicrobial resistant K. pneumoniae isolate is hypervirulent. This report determined which combination of genotypic and phenotypic markers could most accurately identify hvKp strains with acquired resistance. Both logistic regression and a machine-learning prediction model demonstrated that biomarker count alone was the strongest predictor. The presence of all five of the biomarkers iucA, iroB, peg-344, rmpA, and rmpA2 was most accurate (94%); the presence of ≥4 of these biomarkers was most sensitive (100%). Accurately identifying hvKp is vital for surveillance and research, and the availability of biomarker data could alert the clinician that hvKp is a consideration, which, in turn, would assist in optimizing patient care.

Effects of hemodilution on coagulation function during prolonged hypotensive resuscitation in a porcine model of severe hemorrhagic shock

Background

Although hemorrhage remains the leading cause of survivable death in casualties, modern conflicts are becoming more austere limiting available resources to include resuscitation products. With limited resources also comes prolonged evacuation time, leaving suboptimal prehospital field care conditions. When blood products are limited or unavailable, crystalloid becomes the resuscitation fluid of choice. However, there is concern of continuous crystalloid infusion during a prolonged period to achieve hemodynamic stability for a patient. This study evaluates the effect of hemodilution from a 6-hour prehospital hypotensive phase on coagulation in a porcine model of severe hemorrhagic shock.

Methods

Adult male swine (n=5/group) were randomized into three experimental groups. Non-shock (NS)/normotensive did not undergo injury and were controls. NS/permissive hypotensive (PH) was bled to the PH target of systolic blood pressure (SBP) 85±5 mm Hg for 6 hours of prolonged field care (PFC) with SBP maintained via crystalloid, then recovered. Experimental group underwent controlled hemorrhage to mean arterial pressure 30 mm Hg until decompensation (Decomp/PH), followed by PH resuscitation with crystalloid for 6 hours. Hemorrhaged animals were then resuscitated with whole blood and recovered. Blood samples were collected at certain time points for analysis of complete blood counts, coagulation function, and inflammation.

Results

Throughout the 6-hour PFC, hematocrit, hemoglobin, and platelets showed significant decreases over time in the Decomp/PH group, indicating hemodilution, compared with the other groups. However, this was corrected with whole blood resuscitation. Despite the appearance of hemodilution, coagulation and perfusion parameters were not severely compromised.

Conclusions

Although significant hemodilution occurred, there was minimal impact on coagulation and endothelial function. This suggests that it is possible to maintain the SBP target to preserve perfusion of vital organs at a hemodilution threshold in resource-constrained environments. Future studies should address therapeutics that can mitigate potential hemodilutional effects such as lack of fibrinogen or platelets.

Level of evidence

Not applicable-Basic Animal Research.

Mechanisms of IS26-Mediated Amplification of the aphA1 Gene Leading to Tobramycin Resistance in an Acinetobacter baumannii Isolate

Enhanced levels of resistance to antibiotics arising from amplification of an antibiotic resistance gene that impact therapeutic options are increasingly observed. Amplification can also disclose novel phenotypes leading to treatment failure. However, the mechanism is poorly understood. Here, the route to amplification of the aphA1 kanamycin and neomycin resistance gene during tobramycin treatment of an Acinetobacter baumannii clinical isolate, leading to tobramycin resistance and treatment failure, was investigated. In the tobramycin-susceptible parent isolate, MRSN56, a single copy of aphA1 is present in the pseudocompound transposon PTn6020, bounded by directly oriented copies of IS26. For two clinical resistant isolates, new long-read sequence data were combined with available short-read data to complete the genomes. Comparison to the completed genome of MRSN56 revealed that, in both cases, IS26 had generated a circular translocatable unit (TU) containing PTn6020 and additional adjacent DNA. In one case, this TU was reincorporated into the second product generated by the deletion that formed the TU via the targeted conservative route and amplified about 7 times. In the second case, the TU was incorporated at a new location via the copy-in route and amplified about 65 times. Experimental amplification ex vivo by subjecting MRSN56 to tobramycin selection pressure yielded different TUs, which were incorporated at either the original location or a new location and amplified many times. The outcomes suggest that when IS26 is involved, amplification occurs via rolling circle replication of a newly formed TU coupled to the IS26-mediated TU formation or reincorporation step. IMPORTANCE Heteroresistance, a significant issue that is known to impact antibiotic treatment outcomes, is caused by the presence of spontaneously arising cells with elevated levels of resistance to therapeutically important antibiotics in a population of susceptible cells. Gene amplification is one well-documented cause of heteroresistance, but precisely how extensive amplification occurs is not understood. Here, we establish the case for the direct involvement of IS26 activity in the amplification of the aphA1 gene to disclose resistance to tobramycin. The aphA1 gene is usually found associated with IS26 in Gram-negative pathogens and is commonly found in extensively resistant Acinetobacter baumannii strains. IS26 and related IS cause adjacent deletions, forming a nonreplicating circular molecule known as a translocatable unit (TU), and amplification via a rolling circle mechanism appears to be coupled to either IS26-mediated TU formation or reincorporation. Related IS found in Gram-positive pathogens may play a similar role.

Captopril reduces lung inflammation and accelerated senescence in response to thoracic radiation in mice

The lung is sensitive to radiation and exhibits several phases of injury, with an initial phase of radiation-induced pneumonitis followed by delayed and irreversible fibrosis. The angiotensin-converting enzyme inhibitor captopril has been demonstrated to mitigate radiation lung injury and to improve survival in animal models of thoracic irradiation, but the mechanism remains poorly understood. Here we investigated the effect of captopril on early inflammatory events in the lung in female CBA/J mice exposed to thoracic X-ray irradiation of 17-17.9 Gy (0.5-0.745 Gy min-1). For whole-body + thoracic irradiation, mice were exposed to 7.5 Gy (0.6 Gy min-1) total-body 60Co irradiation and 9.5 Gy thoracic irradiation. Captopril was administered orally (110 mg kg-1 day-1) in the drinking water, initiated 4 h through to150 days post-irradiation. Captopril treatment increased survival from thoracic irradiation to 75% at 150 days compared with 0% survival in vehicle-treated animals. Survival was characterized by a significant decrease in radiation-induced pneumonitis and fibrosis. Investigation of early inflammatory events showed that captopril significantly attenuated macrophage accumulation and decreased the synthesis of radiation-induced interleukin-1β (IL-1β) and tumor necrosis factor-α (TNF-α) pro-inflammatory cytokines in the lungs of irradiated mice. Suppression of IL-1β and TNF-α correlated with an increase of the anti-inflammatory cytokine IL-10 in the spleen with captopril treatment. We also found that captopril decreased markers for radiation-induced accelerated senescence in the lung tissue. Our data suggest that suppression of inflammation and senescence markers, combined with an increase of anti-inflammatory factors, are a part of the mechanism for captopril-induced survival in thoracic irradiated mice.

Molecular Detection of Filamentous Fungi in Formalin-Fixed Paraffin-Embedded Specimens in Invasive Fungal Wound Infections Is Feasible with High Specificity

Trauma-related invasive fungal wound infections (IFIs) are associated with significant morbidity and mortality. Early identification and treatment are critical. Traditional identification methods (e.g., fungal cultures and histopathology) can be delayed and insensitive. We assessed a PCR-based sequencing assay for rapid identification of filamentous fungi in formalin-fixed paraffin-embedded (FFPE) specimens obtained from combat casualties injured in Afghanistan. Blinded FFPE specimens from cases (specimens positive on histopathology) and controls (specimens negative on histopathology) were submitted for evaluation with a panfungal PCR. The internal transcribed spacer 2 (ITS2) region of the fungal ribosomal repeat was amplified and sequenced. The PCR results were compared with findings from histopathology and/or culture. If injury sites contributed multiple specimens, findings for the site were collapsed to the site level. We included 64 case subjects (contributing 95 sites) and 102 controls (contributing 118 sites). Compared to histopathology, panfungal PCR was specific (99%), but not as sensitive (63%); however, sensitivity improved to 83% in specimens from sites with angioinvasion. Panfungal PCR identified fungi of the order Mucorales in 33 of 44 sites with angioinvasion (75%), whereas fungal culture was positive in 20 of 44 sites (45%). Saksenaea spp. were the dominant fungi identified by PCR in specimens from angioinvasion sites (57%). Panfungal PCR is specific, albeit with lower sensitivity, and performs better at identifying fungi of the order Mucorales than culture. DNA sequencing offers significant promise for the rapid identification of fungal infection in trauma-related injuries, leading to more timely and accurate diagnoses.

ECMO with vasopressor use during early endotoxic shock: Can it improve circulatory support and regional microcirculatory blood flow?

Introduction

While extracorporeal membrane oxygenation (ECMO) is effective in preventing further hypoxemia and maintains blood flow in endotoxin-induced shock, ECMO alone does not reverse the hypotension. In this study, we tested whether concurrent vasopressor use with ECMO would provide increased circulatory support and blood flow, and characterized regional blood flow distribution to vital organs.

Methods

Endotoxic shock was induced in piglets to achieve a 30% decrease in mean arterial pressure (MAP). Measurements of untreated pigs were compared to pigs treated with ECMO alone or ECMO and vasopressors.

Results

ECMO provided cardiac support during vasodilatory endotoxic shock and improved oxygen delivery, but vasopressor therapy was required to return MAP to normotensive levels. Increased blood pressure with vasopressors did not alter oxygen consumption or extraction compared to ECMO alone. Regional microcirculatory blood flow (RBF) to the brain, kidney, and liver were maintained or increased during ECMO with and without vasopressors.

Conclusion

ECMO support and concurrent vasopressor use improve regional blood flow and oxygen delivery even in the absence of full blood pressure restoration. Vasopressor-induced selective distribution of blood flow to vital organs is retained when vasopressors are administered with ECMO.

Complement inhibition ameliorates blast-induced acute lung injury in rats: Potential role of complement in intracellular HMGB1-mediated inflammation

BACKGROUND AND OBJECTIVE

Complement activation as an early and important inflammatory process contributes to multiple organ dysfunction after trauma. We have recently shown that complement inhibition by decay-accelerating factor (DAF) protects brain from blast-overpressure (BOP)-induced damage. This study was conducted to determine the effect of DAF on acute lung injury induced by BOP exposure and to elucidate its possible mechanisms of action.

METHODS

Anesthetized adult male Sprague-Daley rats were exposed to BOP (120 kPa) from a compressed air-driven shock tube. Rats were randomly assigned to three experimental groups: 1) Control (no BOP and no DAF treatment), 2) BOP (120 kPa BOP exposure), and 3) BOP followed by treatment with rhDAF (500μg/kg, i.v) at 30 minutes after blast. After a recovery period of 3, 24, or 48 hours, animals were euthanized followed by the collection of blood and tissues at each time point. Samples were subjected to the assessment of cytokines and histopathology as well as for the interaction of high-mobility-group box 1 (HMGB1) protein, NF-κB, receptor for advanced glycation end products (RAGE), C3a, and C3aR.

RESULTS

BOP exposure significantly increased in the production of systemic pro- and anti-inflammatory cytokines, and obvious pathological changes as characterized by pulmonary edema, inflammation, endothelial damage and hemorrhage in the lungs. These alterations were ameliorated by early administration of rhDAF. The rhDAF treatment not only significantly reduced the expression levels of HMGB1, RAGE, NF-κB, C3a, and C3aR, but also reversed the interaction of C3a-C3aR and nuclear translocation of HMGB1 in the lungs.

CONCLUSIONS

Our findings indicate that early administration of DAF efficiently inhibits systemic and local inflammation, and mitigates blast-induced lung injury. The underlying mechanism might be attributed to its potential modulation of C3a-C3aR-HMGB1-transcriptional factor axis. Therefore, complement and/or HMGB1 may be potential therapeutic targets in amelioration of acute lung injury after blast injury.