Determining Which Combinatorial Combat-Relevant Factors Contribute to Heterotopic Ossification Formation in an Ovine Model

Traumatic heterotopic ossification (HO) is frequently observed in Service Members following combat-related trauma. Estimates suggest that ~65% of wounded warriors who suffer limb loss or major extremity trauma will experience some type of HO formation. The development of HO delays rehabilitation and can prevent the use of a prosthetic. To date there are limited data to suggest a standard mechanism for preventing HO. This may be due to inadequate animal models not producing a similar bone structure as human HO. We recently showed that traumatic HO growth is possible in an ovine model. Within that study, we demonstrated that 65% of sheep developed a human-relevant hybrid traumatic HO bone structure after being exposed to a combination of seven combat-relevant factors. Although HO formed, we did not determine which traumatic factor contributed most. Therefore, in this study, we performed individual and various combinations of surgical/traumatic factors to determine their individual contribution to HO growth. Outcomes showed that the presence of mature biofilm stimulated a large region of bone growth, while bone trauma resulted in a localized bone response as indicated by jagged bone at the linea aspera. However, it was not until the combinatory factors were included that an HO structure similar to that of humans formed more readily in 60% of the sheep. In conclusion, data suggested that traumatic HO growth can develop following various traumatic factors, but a combination of known instigators yields higher frequency size and consistency of ectopic bone.

Ex vivo comparison of V.A.C.® Granufoam Silver™ and V.A.C.® Granufoam™ loaded with a first-in-class bis-dialkylnorspermidine-terphenyl antibiofilm agent

Implementation of negative pressure wound therapy (NPWT) as a standard of care has proven efficacious in reducing both the healing time and likelihood of nosocomial infection among pressure ulcers and traumatic, combat-related injuries. However, current formulations may not target or dramatically reduce bacterial biofilm burden following therapy. The purpose of this study was to determine the antibiofilm efficacy of an open-cell polyurethane (PU) foam (V.A.C.® Granufoam™) loaded with a first-in-class compound (CZ-01179) as the active release agent integrated via lyophilized hydrogel scaffolding. An ex vivo porcine excision wound model was designed to perform antibiofilm efficacy testing in the presence of NPWT. PU foam samples loaded with a 10.0% w/w formulation of CZ-01179 and 0.5% hyaluronic acid were prepared and tested against current standards of care: V.A.C.® Granufoam Silver™ and V.A.C.® Granufoam™. We observed statistically significant reduction of methicillin-resistant Staphylococcus aureus (MRSA) and Acinetobacter baumannii biofilms with the CZ-01179 antibiofilm foam in comparison to current standard of care foams. These findings motivate further development of an antibiofilm PU foam loaded with CZ-01179.

All-cause and cause-specific mortality rates after severe extremity injuries among previously deployed active duty service members

BACKGROUND

Previous research has shown that active duty military personnel who sustain extremity injuries while in service are at elevated risk for serious physical and psychological health issues that could affect their long-term functioning and quality of life yet longer-term mortality has not been studied in this population.

OBJECTIVE

To determine whether rates of all-cause and cause-specific mortality are elevated for active duty U.S. service members who sustained traumatic limb injuries in service, compared to the broader population of deploying service members. To assess differences in mortality rates between service members with traumatic limb injuries that did versus did not result in amputation.

DESIGN

Retrospective cohort study; archival Department of Defense deployment, personnel, medical, and death records were combined and analyzed. Standardized mortality ratios (SMR) adjusted for age, sex, and ethnoracial group, along with associated 95% confidence intervals (CIs), were calculated to directly compare all-cause and cause-specific mortality rates in each of the two injury groups to rates in the total study population.

SETTING

Not applicable.

PARTICIPANTS

Service members who deployed in support of the global war on terror between 2001 and 2016 were eligible for inclusion; the final sample included 1,875,206 individuals surveilled through 2019.

INTERVENTION

Not applicable.

MAIN OUTCOME MEASURES

All-cause and cause-specific mortality rates.

RESULTS

Overall, the number of deaths was over three times higher than expected among service members with amputations (SMR = 3.01; CI: 2.36-3.65), and nearly two times higher among those with serious limb injuries not resulting in amputation (SMR = 1.72; CI: 1.54-1.90) when compared to the larger study population. Rates for both internal and external causes of death were significantly elevated among those with limb injuries.

CONCLUSIONS

Long-term mortality rates are elevated among service members with traumatic limb injuries, though mortality patterns may differ based on whether the injury results in amputation. Although further research into causal mechanisms is needed, these results may inform the development of interventions to improve long-term health outcomes among injured military personnel.

Antibiofilm potential of a negative pressure wound therapy foam loaded with a first-in-class tri-alkyl norspermidine-biaryl antibiotic

Negative-pressure wound therapy (NPWT) is commonly utilized to treat traumatic injuries sustained on the modern battlefield. However, NPWT has failed to decrease the incidence of deep tissue infections experienced by Wounded Warriors, despite attempts to integrate common antimicrobials, like Ag+ nanoparticles, into the wound dressing. The purpose of this study was to incorporate a unique antibiofilm compound (CZ-01179) into the polyurethane matrix of NPWT foam via lyophilized hydrogel scaffolding. Foam samples with 2.5%, 5.0%, and 10.0% w/w CZ-01179 were produced and antibiofilm efficacy was compared to the current standards of care: V.A.C.® GRANUFOAM SILVER™ and V.A.C.® GRANUFOAM™. Gravimetric analysis and elution kinetics testing confirmed that this loading technique was both repeatable and controllable. Furthermore, zone of inhibition and antibiofilm efficacy testing showed that foam loaded with CZ-01179 had significantly increased activity against planktonic and biofilm phenotypes of methicillin-resistant Staphylococcus aureus and Acinetobacter baumannii compared to the clinical standards. These findings motivate additional ex vivo and in vivo work with NPWT foam loaded with CZ-01179 with the overall objective of reducing NPWT-associated infections that complicate battlefield-related and other wounds.

Developing a combat-relevant translatable large animal model of heterotopic ossification

Heterotopic ossification (HO) refers to ectopic bone formation, typically in residual limbs following trauma and injury. A review of injuries from Operation Iraqi Freedom (OIF) and Operation Enduring Freedom (OEF) indicated that approximately 70% of war wounds involved the musculoskeletal system, largely in part from the use of improvised explosive devices (IED) and rocket-propelled grenades (RPG). HO is reported to occur in approximately 63%–65% of wounded warriors from OIF and OEF. Symptomatic HO may delay rehabilitation regimens since it often requires modifications to prosthetic limb componentry and socket size. There is limited evidence indicating a mechanism for preventing HO. This may be due to inadequate models, which do not produce HO bone structure that is morphologically similar to HO samples obtained from wounded warfighters injured in theatre. We hypothesized that using a high-power blast of air (shockwave) and simulated battlefield trauma (i.e. bone damage, tourniquet, bacteria, negative pressure wound therapy) in a large animal model, HO would form and have similar morphology to ectopic bone observed in clinical samples. Initial radiographic and micro-computed tomography (CT) data demonstrated ectopic bone growth in sheep 24 weeks post-procedure. Advanced histological and backscatter electron (BSE) analyses showed that 5 out of 8 (63%) sheep produced HO with similar morphology to clinical samples. We conclude that not all ectopic bone observed by radiograph or micro-CT in animal models is HO. Advanced histological and BSE analyses may improve confirmation of HO presence and morphology, which we demonstrated can be produced in a large animal model.

The practical utility of genetic screening in school settings

Can genetic screening be used to personalize education for students? Genome-wide association studies (GWAS) screen an individual's DNA for specific variations in their genome, and how said variations relate to specific traits. The variations can then be assigned a corresponding weight and summed to produce polygenic scores (PGS) for given traits. Though first developed for disease risk, PGS is now used to predict educational achievement. Using a novel simulation method, this paper examines if PGS could advance screening in schools, a goal of personalized education. Results show limited potential benefits for using PGS to personalize education for individual students. However, further analysis shows PGS can be effectively used alongside progress monitoring measures to screen for learning disability risk. Altogether, PGS is not useful in personalizing education for every child but has potential utility when used simultaneously with additional screening tools to help determine which children may struggle academically.

High Bilateral Amputations and Dismounted Complex Blast Injury (DCBI)

High, combat-related bilateral lower extremity amputations rarely occur in isolation. Dismounted complex blast injury is a devastating and life-threatening constellation of multisystem injuries most commonly due to dismounted contact with improvised explosive devices. Rapid damage control resuscitation and surgery are essential to improve patient survival and minimize both early complications and late sequelae. A coordinated team approach is essential to provide simultaneous airway management, volume resuscitation (ideally with whole blood or ratio transfusion), and immediate control of life-threatening hemorrhage. Temporary aortic or iliac vessel clamping during concurrent exploratory or vascular control laparotomy is frequently required. Stabilization of unstable pelvic fractures is then performed, followed by debridement and irrigation of all wounds, which should be left open, and subsequent provisional stabilization of long bone fractures. The goal of the initial surgical resuscitative endeavor is rapid concurrent control of all sources of hemorrhage to avoid the lethal triad of acidosis, hypothermia and coagulopathy. To this end, multiple surgeons or surgical teams should be utilized whenever feasible. Patients then require ongoing resuscitation followed by early and frequent return to the operating suite throughout the evacuation chain. Utilizing this approach, a high survival rate with reasonable functional outcomes is achievable despite the extreme severity of the DCBI pattern.

Amputation: Evaluation and Treatment

Combat extremity injury and amputation is a life threatening injury. Initial surgical care should focus on hemostasis followed by irrigation and debridement of contaminated and nonviable tissue. Preservation of limb length begins at the initial surgical procedure, to include retention of atypical soft tissue flaps for later reconstruction and treatment of proximal fractures. Serial irrigation and debridements are required throughout the MEDEVAC system as the evolving zone of injury becomes more mature, followed by the appropriate timing of closure outside the combat theater.

Polyamines eliminate an extreme size bias against transformation of large yeast artificial chromosome DNA

The recent development of vectors and methods for cloning large linear DNA as yeast artificial chromosomes (YACs) has enormous potential in facilitating genome analysis, particularly because of the large cloning capacity of the YAC cloning system. However, the construction of comprehensive libraries with very large DNA segments (400-500 kb average insert size) has been technically very difficult to achieve. We have examined the possibility that this difficulty is due, at least in part, to preferential transformation of the smaller DNA molecules in the yeast transformation mixture. Our data indicate that the transformation efficiency of a 330-kb linear YAC DNA molecule is 40-fold lower, on a molar basis, than that of a 110-kb molecule. This extreme size bias in transformation efficiency is dramatically reduced (to less than 3-fold) by treating the DNA with millimolar concentrations of polyamines prior to and during transformation into yeast spheroplasts. This effect is accounted for by a stimulation in transformation efficiency of the 330-kb YAC molecule; the transformation efficiency of the 110-kb YAC molecule is not affected by the inclusion of polyamines. Application of this finding to the cloning of large exogenous DNA as artificial chromosomes in yeast will facilitate the construction of genomic libraries with significantly increased average insert sizes. In addition, the methods described allow efficient transfer of YACs to yeast strain backgrounds suitable for subsequent manipulations of the large insert DNA.