Model for Evaluating Antimicrobial Therapy To Prevent Life-Threatening Bacterial Infections following Exposure to a Medically Significant Radiation Dose.

More evidence is needed to support recommendations for medical management of acute radiation syndrome (ARS) and associated infections resulting from a radiological/nuclear event. While current guidelines recommend the administration of antibiotics to chemotherapy patients with febrile neutropenia, the clinical benefit is unclear for acute radiation injury patients. A well-characterized nonhuman primate (NHP) model of hematopoietic ARS was developed that incorporates supportive care postirradiation. This model evaluated the efficacy of myeloid growth factors within 24 to 48 h after total body irradiation (TBI). However, in this model, NHPs continued to develop life-threatening bacterial infections, even when granulocyte colony-stimulating factor or granulocyte-macrophage colony-stimulating factor was administered in combination with antibiotic monotherapy. In this study, we evaluated the efficacy of combination antibiotic therapies administered to NHPs following 7.4-Gy TBI to understand the occurrence of bacterial infection in NHPs with hematopoietic ARS. We compared enrofloxacin-linezolid, enrofloxacin-cefepime, and enrofloxacin-ertapenem to enrofloxacin monotherapy. The primary endpoint was 60-day postirradiation mortality, with secondary endpoints of overall survival time, incidence of bacterial infection, and bacteriologic culture with antimicrobial susceptibility testing. We observed that enrofloxacin-ertapenem significantly increased survival compared to enrofloxacin monotherapy. Bacteria isolated from nonsurviving macaques with systemic bacterial infections exhibited uniform resistance to enrofloxacin and variable resistance to beta-lactam antibiotics, linezolid, gentamicin, and azithromycin. Multidrug antibiotic resistance was observed in Enterococcus spp. and Escherichia coli. We conclude that antibiotic combination therapies appear to be more effective than monotherapy alone but acknowledge that more work is needed to identify an optimal antimicrobial therapy.

Partnering on vaccines to counter multi-drug resistant threats: Workshop proceedings, Biomedical Advanced Research and Development Authority.

On March 12, 2021, the Biomedical Advanced Research and Development Authority (BARDA) sponsored a virtual market research workshop, "Partnering on Vaccines to Counter Multi-Drug Resistant Threats," to discuss the threat of antimicrobial resistance in the context of BARDA's mission space and the challenges encountered during the development of vaccines for specific antimicrobial resistant bacteria. The workshop convened representatives with expertise in vaccine development from government, academia, and industry. This report summarizes the presentations and subsequent discussions from the workshop and highlights existing challenges to advance the development of vaccine candidates for antimicrobial resistant pathogens, including Escherichia coli, Klebsiella pneumoniae, Pseudomonas aeruginosa, and Staphylococcus aureus.

Machine Learning Approach to Predicting Stem Cell Donor Availability.

The success of unrelated donor stem cell transplants depends on not only finding genetically matched donors, but also donor availability. On average 50% of potential donors in the National Marrow Donor Program database are unavailable for a variety of reasons, after initially matching a patient, with significant variations in availability among subgroups (eg, by race or age). Several studies have established univariate donor characteristics associated with availability. Individual consideration of each applicable characteristic is laborious. Extrapolating group averages to the individual-donor level tends to be highly inaccurate. In the current environment with enhanced donor data collection, we can make better estimates of individual donor availability. We propose a machine learning based approach to predict availability of every registered donor, and evaluate the predictive power on a test cohort of 44,544 requests to be .77 based on the area under the receiver-operating characteristic curve. We propose that this predictor should be used during donor selection to reduce the time to transplant.

Modeling coverage gaps in haplotype frequencies via Bayesian inference to improve stem cell donor selection.

Regardless of sampling depth, accurate genotype imputation is limited in regions of high polymorphism which often have a heavy-tailed haplotype frequency distribution. Many rare haplotypes are thus unobserved. Statistical methods to improve imputation by extending reference haplotype distributions using linkage disequilibrium patterns that relate allele and haplotype frequencies have not yet been explored. In the field of unrelated stem cell transplantation, imputation of highly polymorphic human leukocyte antigen (HLA) genes has an important application in identifying the best-matched stem cell donor when searching large registries totaling over 28,000,000 donors worldwide. Despite these large registry sizes, a significant proportion of searched patients present novel HLA haplotypes. Supporting this observation, HLA population genetic models have indicated that many extant HLA haplotypes remain unobserved. The absent haplotypes are a significant cause of error in haplotype matching. We have applied a Bayesian inference methodology for extending haplotype frequency distributions, using a model where new haplotypes are created by recombination of observed alleles. Applications of this joint probability model offer significant improvement in frequency distribution estimates over the best existing alternative methods, as we illustrate using five-locus HLA frequency data from the National Marrow Donor Program registry. Transplant matching algorithms and disease association studies involving phasing and imputation of rare variants may benefit from this statistical inference framework.

On Modeling Human Leukocyte Antigen-Identical Sibling Match Probability for Allogeneic Hematopoietic Cell Transplantation: Estimating the Need for an Unrelated Donor Source.

Prior studies of allogeneic hematopoietic cell transplantation (HCT) therapy for the treatment of malignant or nonmalignant blood disorders assume a 30% likelihood that a patient will find a match among siblings and, therefore, a 70% likelihood of needing an unrelated donor source. This study utilizes birth data and statistical modeling to assess the adequacy of these estimates to describe the probability among US population cohorts segmented by race/ethnicity and age, including ages of greatest HCT utilization. Considerable variation in the likelihood of an HLA-identical sibling was found, ranging from 13% to 51%, depending upon patient age and race/ethnicity. Low sibling match probability, compounded with increased genetic diversity and lower availability among unrelated donors, put the youngest minority patients at the greatest risk for not finding a suitable related or unrelated HCT donor. Furthermore, the present 40-year decline in birth rates is expected to lead to 1.5-fold decrease in access to a matched sibling for today's young adults (18 to 44 years of age) when they reach peak HCT utilization years (near age 61 years) versus their contemporary adult counterparts (44 to 64 years). Understanding the sibling match probability by race/ethnicity and age cohort leads to forecasting the demand for unrelated HCT sources.

Asymmetric linkage disequilibrium: Tools for assessing multiallelic LD.

Standard measures of linkage disequilibrium (LD) provide an incomplete description of the correlation between two loci. Recently, Thomson and Single (2014) described a new asymmetric pair of LD measures (ALD) that give a more complete description of LD. The ALD measures are symmetric and equivalent to the correlation coefficient r when both loci are bi-allelic. When the numbers of alleles at the two loci differ, the ALD measures capture this asymmetry and provide additional detail about the LD structure. In disease association studies the ALD measures are useful for identifying additional disease genes in a genetic region, by conditioning on known effects. In evolutionary genetic studies ALD measures provide insight into selection acting on individual amino acids of specific genes, or other loci in high LD (see Thomson and Single (2014) for these examples). Here we describe new software for computing and visualizing ALD. We demonstrate the utility of this software using haplotype frequency data from the National Marrow Donor Program (NMDP). This enhances our understanding of LD patterns in the NMDP data by quantifying the degree to which LD is asymmetric and also quantifies this effect for individual alleles.

Clinical outcomes associated with the initial use of the Canine Unicompartmental Elbow (CUE) Arthroplasty System(®).

We evaluated mid- to long-term outcomes with respect to function and complications in dogs undergoing canine unicompartmental elbow (CUE) arthroplasty for treatment of medial compartment disease of the elbow. This prospective multicenter case series is the first group of clinical cases to receive CUE arthroplasty. Cases (each elbow that underwent CUE performed by a participating surgeon) were enrolled into an electronic database and prospectively followed to determine and record all associated complications, as well as functional outcomes. There were 103 cases from 18 surgeons. Final follow-up time ranged from 6 to 47 mo with a mean and median of 10 mo. Canine unicompartmental elbow was associated with 1 catastrophic (1%), 11 major (10.7%), and 28 minor (27.2%) complications. Outcomes following CUE were reported as full function in 49 cases (47.6%), acceptable function in 45 cases (43.7%), and unacceptable function in 9 cases (8.7%). We conclude that CUE arthroplasty is an appropriate consideration for treatment of medial compartment disease of the elbow in dogs.

Résultats cliniques associés à l'utilisation initiale du système d'arthroplastieCanine Unicompartmental Elbow (CUE) Arthroplasty SystemMD. Nous avons évalué les résultats à long et à moyen terme relativement à la fonction et aux complications chez les chiens subissant une arthroplastie du coude unicompartimental canin (CUC) pour le traitement de la maladie compartimentale médiale du coude. Cette série prospective de cas multicentres représente le premier groupe de cas cliniques à recevoir une arthroplastie CUC. Les cas (chaque coude qui a subi une CUC réalisée par un chirurgien participant) étaient inscrits dans une base de données électroniques et suivis de manière prospective afin de déterminer et de consigner toutes les complications connexes ainsi que les résultats fonctionnels. Il y avait 103 cas provenant de 18 chirurgiens. Le temps de suivi final s'échelonnait de 6 à 47 mois avec une moyenne et une médiane de 10 mois. Le coude compartimental canin a été associé à 1 complication catastrophique (1 %), à 11 complications majeures (10,7 %) et à 28 complications mineures (27,2 %). Les résultats après l'arthroplastie CUC ont été signalés comme une fonction complète dans 49 cas (47,6 %), une fonction acceptable dans 45 cas (43,7 %) et une fonction inacceptable dans 9 cas (8,7 %). Nous avons conclu que l'arthroplastie CUC est une considération appropriée pour le traitement de la maladie compartimentale médiale du coude chez les chiens.(Traduit par Isabelle Vallières).

Race, Ethnicity and Ancestry in Unrelated Transplant Matching for the National Marrow Donor Program: A Comparison of Multiple Forms of Self-Identification with Genetics.

We conducted a nationwide study comparing self-identification to genetic ancestry classifications in a large cohort (n = 1752) from the National Marrow Donor Program. We sought to determine how various measures of self-identification intersect with genetic ancestry, with the aim of improving matching algorithms for unrelated bone marrow transplant. Multiple dimensions of self-identification, including race/ethnicity and geographic ancestry were compared to classifications based on ancestry informative markers (AIMs), and the human leukocyte antigen (HLA) genes, which are required for transplant matching. Nearly 20% of responses were inconsistent between reporting race/ethnicity versus geographic ancestry. Despite strong concordance between AIMs and HLA, no measure of self-identification shows complete correspondence with genetic ancestry. In certain cases geographic ancestry reporting matches genetic ancestry not reflected in race/ethnicity identification, but in other cases geographic ancestries show little correspondence to genetic measures, with important differences by gender. However, when respondents assign ancestry to grandparents, we observe sub-groups of individuals with well- defined genetic ancestries, including important differences in HLA frequencies, with implications for transplant matching. While we advocate for tailored questioning to improve accuracy of ancestry ascertainment, collection of donor grandparents' information will improve the chances of finding matches for many patients, particularly for mixed-ancestry individuals.

Power laws for heavy-tailed distributions: modeling allele and haplotype diversity for the national marrow donor program.

Measures of allele and haplotype diversity, which are fundamental properties in population genetics, often follow heavy tailed distributions. These measures are of particular interest in the field of hematopoietic stem cell transplant (HSCT). Donor/Recipient suitability for HSCT is determined by Human Leukocyte Antigen (HLA) similarity. Match predictions rely upon a precise description of HLA diversity, yet classical estimates are inaccurate given the heavy-tailed nature of the distribution. This directly affects HSCT matching and diversity measures in broader fields such as species richness. We, therefore, have developed a power-law based estimator to measure allele and haplotype diversity that accommodates heavy tails using the concepts of regular variation and occupancy distributions. Application of our estimator to 6.59 million donors in the Be The Match Registry revealed that haplotypes follow a heavy tail distribution across all ethnicities: for example, 44.65% of the European American haplotypes are represented by only 1 individual. Indeed, our discovery rate of all U.S. European American haplotypes is estimated at 23.45% based upon sampling 3.97% of the population, leaving a large number of unobserved haplotypes. Population coverage, however, is much higher at 99.4% given that 90% of European Americans carry one of the 4.5% most frequent haplotypes. Alleles were found to be less diverse suggesting the current registry represents most alleles in the population. Thus, for HSCT registries, haplotype discovery will remain high with continued recruitment to a very deep level of sampling, but population coverage will not. Finally, we compared the convergence of our power-law versus classical diversity estimators such as Capture recapture, Chao, ACE and Jackknife methods. When fit to the haplotype data, our estimator displayed favorable properties in terms of convergence (with respect to sampling depth) and accuracy (with respect to diversity estimates). This suggests that power-law based estimators offer a valid alternative to classical diversity estimators and may have broad applicability in the field of population genetics.

Fine-mapping of HLA associations with chronic lymphocytic leukemia in US populations.

Chronic lymphocytic leukemia (CLL) displays remarkable ethnic predisposition for whites, with relative sparing of African-American and Asian populations. In addition, CLL displays among the highest familial predispositions of all hematologic malignancies, yet the genetic basis for these differences is not clearly defined. The highly polymorphic HLA genes of the major histocompatibility complex play a central role in immune surveillance and confer risk for autoimmune and infectious diseases and several different cancers, the role for which in the development of CLL has not been extensively investigated. The National Marrow Donor Program/Be The Match has collected HLA typing from CLL patients in need of allogeneic hematopoietic stem cell transplant and has recruited millions of volunteers to potentially donate hematopoietic stem cells. HLA genotypes for 3491 US white, 397 African-American, and 90 Hispanic CLL patients were compared with 50 000 controls per population from the donor registry. We identified several HLA alleles associated with CLL susceptibility in each population, reconfirming predisposing roles of HLA-A*02:01 and HLA-DRB4*01:01 in whites. Associations for haplotype DRB4*01:01∼DRB1*07:01∼DQB1*03:03 were replicated across all 3 populations. These findings provide a comprehensive assessment of the role of HLA in the development of severe CLL.

Challenges, progress, and opportunities: proceedings of the filovirus medical countermeasures workshop.

On August 22-23, 2013, agencies within the United States Department of Defense (DoD) and the Department of Health and Human Services (HHS) sponsored the Filovirus Medical Countermeasures (MCMs) Workshop as an extension of the activities of the Filovirus Animal Non-clinical Group (FANG). The FANG is a federally-recognized multi-Agency group established in 2011 to coordinate and facilitate U.S. government (USG) efforts to develop filovirus MCMs. The workshop brought together government, academic and industry experts to consider the needs for filovirus MCMs and evaluate the status of the product development pipeline. This report summarizes speaker presentations and highlights progress and challenges remaining in the field.

DNA electroporation of multi-agent vaccines conferring protection against select agent challenge: TriGrid delivery system.

Effective multi-agent/multivalent vaccines that confer protection against more than one disease are highly desirable to the patient and to health-care professionals. Electroporation of DNA vaccines, whereby tissues injected with DNA are subjected to localized electrical currents, is an ideal platform technology that achieves protective immune responses to multivalent vaccination. Here, we describe an electroporation-based immunization technique capable of administering a cocktail of DNA vaccinations in vivo. Immune response measurements, including protection from pathogen challenge and induction of antigen-specific antibody responses and cell-mediated immune responses, are also discussed.

Forced-air warming design: evaluation of intake filtration, internal microbial buildup, and airborne-contamination emissions.

Forced-air warming devices are effective for the prevention of surgical hypothermia. However, these devices intake nonsterile floor-level air, and it is unknown whether they have adequate filtration measures to prevent the internal buildup or emission of microbial contaminants. We rated the intake filtration efficiency of a popular current-generation forced-air warming device (Bair Hugger model 750, Arizant Healthcare) using a monodisperse sodium chloride aerosol in the laboratory. We further sampled 23 forced-air warming devices (same model) in daily hospital use for internal microbial buildup and airborne-contamination emissions via swabbing and particle counting. Laboratory testing found the intake filter to be 63.8% efficient. Swabbing detected microorganisms within 100% of the forced-air warming blowers sampled, with isolates of coagulase-negative staphylococci, mold, and micrococci identified. Particle counting showed 96% of forced-air warming blowers to be emitting significant levels of internally generated airborne contaminants out of the hose end. These findings highlight the need for upgraded intake filtration, preferably high-efficiency particulate air filtration (99.97% efficient), on current-generation forced-air warming devices to reduce contamination buildup and emission risks.

Patient warming excess heat: the effects on orthopedic operating room ventilation performance.

BACKGROUND: Patient warming has become a standard of care for the prevention of unintentional hypothermia based on benefits established in general surgery. However, these benefits may not fully translate to contamination-sensitive surgery (i.e., implants), because patient warming devices release excess heat that may disrupt the intended ceiling-to-floor ventilation airflows and expose the surgical site to added contamination. Therefore, we studied the effects of 2 popular patient warming technologies, forced air and conductive fabric, versus control conditions on ventilation performance in an orthopedic operating room with a mannequin draped for total knee replacement. METHODS: Ventilation performance was assessed by releasing neutrally buoyant detergent bubbles ("bubbles") into the nonsterile region under the head-side of the anesthesia drape. We then tracked whether the excess heat from upper body patient warming mobilized the "bubbles" into the surgical site. Formally, a randomized replicated design assessed the effect of device (forced air, conductive fabric, control) and anesthesia drape height (low-drape, high-drape) on the number of bubbles photographed over the surgical site. RESULTS: The direct mass-flow exhaust from forced air warming generated hot air convection currents that mobilized bubbles over the anesthesia drape and into the surgical site, resulting in a significant increase in bubble counts for the factor of patient warming device (P < 0.001). Forced air had an average count of 132.5 versus 0.48 for conductive fabric (P = 0.003) and 0.01 for control conditions (P = 0.008) across both drape heights. Differences in average bubble counts across both drape heights were insignificant between conductive fabric and control conditions (P = 0.87). The factor of drape height had no significant effect (P = 0.94) on bubble counts. CONCLUSIONS: Excess heat from forced air warming resulted in the disruption of ventilation airflows over the surgical site, whereas conductive patient warming devices had no noticeable effect on ventilation airflows. These findings warrant future research into the effects of forced air warming excess heat on clinical outcomes during contamination-sensitive surgery.

Electroporation of a multivalent DNA vaccine cocktail elicits a protective immune response against anthrax and plague.

Electroporation of DNA vaccines represents a platform technology well positioned for the development of multivalent biodefense vaccines. To evaluate this hypothesis, three vaccine constructs were produced using codon-optimized genes encoding Bacillus anthracis Protective Antigen (PA), and the Yersinia pestis genes LcrV and F1, cloned into pVAX1. A/J mice were immunized on a prime-boost schedule with these constructs using the electroporation-based TriGrid Delivery System. Immunization with the individual pDNA vaccines elicited higher levels of antigen-specific IgG than when used in combination. DNA vaccine effectiveness was proven, the pVAX-PA titers were toxin neutralizing and fully protective against a lethal B. anthracis spore challenge when administered alone or co-formulated with the plague pDNA vaccines. LcrV and F1 pVAX vaccines against plague were synergistic, resulting in 100% survival, but less protective individually and when co-formulated with pVAX-PA. These DNA vaccine responses were Th1/Th2 balanced with high levels of IFN-γ and IL-4 in splenocyte recall assays, contrary to complimentary protein Alum vaccinations displaying a Th2 bias with increased IL-4 and low levels of IFN-γ. These results demonstrate the feasibility of electroporation to deliver and maintain the overall efficacy of an anthrax-plague DNA vaccine cocktail whose individual components have qualitative immunological differences when combined.

Immunogenicity and efficacy of an anthrax/plague DNA fusion vaccine in a mouse model.

The efficacy of multi-agent DNA vaccines consisting of a truncated gene encoding Bacillus anthracis lethal factor (LFn) fused to either Yersinia pestis V antigen (V) or Y . pestis F1 was evaluated. A/J mice were immunized by gene gun and developed predominantly IgG1 responses that were fully protective against a lethal aerosolized B. anthracis spore challenge but required the presence of an additional DNA vaccine expressing anthrax protective antigen to boost survival against aerosolized Y. pestis.

Ultra-fast pg/ml anthrax toxin (protective antigen) detection assay based on microwave-accelerated metal-enhanced fluorescence.

Rapid presymptomatic diagnosis of Bacillus anthracis at early stages of infection plays a crucial role in prompt medical intervention to prevent rapid disease progression and accumulation of lethal levels of toxin. To detect low levels of the anthrax protective antigen (PA) exotoxin in biological fluids, we have developed a metal-enhanced fluorescence (MEF)-PA assay using a combination of the MEF effect and microwave-accelerated PA protein surface absorption. The assay is based on a modified version of our "rapid catch and signal" (RCS) technology previously designed for the ultra-fast and sensitive analysis of genomic DNA sequences. Technologically, the proposed MEF-PA assay uses standard 96-well plastic plates modified with silver island films (SiFs) grown within the wells. It is shown that the fluorescent probe, covalently attached to the secondary antibody, plays a crucial role of indicating complex formation (i.e., shows a strong MEF response to the recognition event). Microwave irradiation rapidly accelerates PA deposition onto the surface ("rapid catch"), significantly speeding up the MEF-PA assay and resulting in a total assay run time of less than 40 min with an analytical sensitivity of less than 1 pg/ml PA.