Search Results (31)

Cutaneous Radiation Injuries (CRIs) and wounds within an area of radiation exposure (combined injury, CI) are a significant concern for nuclear accidents and radiation combat/terrorist events. CRIs and CI present unique clinical challenges, and effective countermeasures are urgently needed. Here we describe a murine model of CRI and CI in C57BL/6 mice using 16.9 Gy thoracic X-ray irradiation (5.3 Gy/min, 160 kV) ± experimental wound administered immediately. Wound repair and radiation-induced dermatitis were assessed after irradiation. Our previous studies showed that genistein (200 mg/kg, s.c.), administered 24 h prior to irradiation prevented radiation injuries in two murine models. We investigated the effects of genistein in the CI model. Macroscopic and histological analyses showed that radiation significantly delayed wound closure, although wounds did not significantly alter the progression of radiation dermatitis. Genistein improved the early rate of wound closure and significantly reduced dermatitis in mice. Histological analysis showed that genistein improved skin structure and reduced inflammation and fibrosis. Immunohistochemistry showed that genistein attenuated radiation-induced cyclin-dependent kinase inhibitor 1 (p21/waf1) and α-smooth muscle actin and preserved K15 positive skin adult stem cells. These findings suggest that genistein may be an effective prophylactic against CRIs and CI. Full article

Widespread uses of nuclear materials increase the risk of accidental or intentional radiation exposure, which can result in acute radiation syndrome (ARS). Hematopoietic ARS (H-ARS) occurs at relatively low doses and is potentially lethal without intervention. While several FDA-approved cytokine-based radiomitigators exist, many require repeated dosing, complicating deployment in mass-casualty scenarios. This study evaluated a novel long-acting, murine-reactive granulocyte–macrophage colony-stimulating factor (LA-GM-CSF; mPDM608) as a prophylactic and mitigative countermeasure for H-ARS. Male and female C57BL/6 mice were exposed to lethal or sublethal total body irradiation (TBI) and treated with LA-GM-CSF using single- or multi-dose regimens administered before or after TBI. Safety, 30-day survival, hematologic recovery, bone marrow cellularity, serum GM-CSF pharmacokinetics, endothelial injury markers, and cytokine profiles were assessed using standard hematology, histopathology, ELISA, and multiplex assays. LA-GM-CSF was well tolerated at doses up to 30 mg/kg. Single or limited dosing conferred significant survival benefits compared with vehicle controls, with optimal efficacy observed at lower doses (3 mg/kg). Post-TBI administration as a single dose 24 h after exposure markedly improved survival in both sexes, with stronger hematopoietic recovery in males. LA-GM-CSF accelerated recovery of neutrophils, red blood cells, platelets, hematocrit, and sternal megakaryocytes, prolonged circulating GM-CSF levels, and favorably modulated endothelial injury markers and select cytokines. LA-GM-CSF demonstrates strong potential as a next-generation radiation countermeasure, providing robust survival benefit and hematopoietic recovery with minimal dosing. The results shown here support further development for H-ARS management under the FDA Animal Rule. Full article

No US Food and Drug Administration (FDA)-approved prophylaxis is currently available for Acute Radiation Syndrome (ARS), which remains a significant threat to military and civilian populations. In this study, we investigated Vasculotide (VT), a Tie2 receptor agonist mimic, as a novel pre-exposure prophylaxis designed to stabilize the vascular endothelium, one of primary targets of radiation-induced damage. To evaluate its efficacy, female B6D2F1/J mice were exposed to 9.5 Gy total body irradiation (TBI), with VT administered subcutaneously at 12 and 2 h prior to exposure. Assessments included 30-day survival, biomarkers of vascular injury, proinflammatory cytokine/chemokine profiling, and evaluation of hematopoietic (H) and gastrointestinal (GI) recovery. Our findings demonstrate that VT significantly increased 30-day survival in a dose-dependent manner, achieving a 30% survival advantage at the 20 μg/kg dose. Furthermore, VT provided robust protection against radiation-induced vascular activation and injury, effectively alleviating damage to the bone marrow (BM) and GI tract. Taken together, these results identify VT as a promising prophylactic countermeasure for ARS. By targeting the Tie2 pathway to preserve vascular integrity, VT addresses a critical gap in medical countermeasures, offering a viable strategy to enhance survival and accelerate multi-organ recovery in radiological mass-casualty scenarios. Full article

The complexity of adverse responses from radiation injury (RI) followed by physical trauma, namely, radiation combined injury (RCI), is unique and more pronounced than either insult alone due to a poor understanding of the integration of these insults at the molecular/cellular/tissue and/or organ levels. It was shown that mice receiving ⁶⁰Co γ-photon RCI with wounding had a lower LD_50/30 than RI alone. This survival synergism was observed in bone marrow and the gastrointestinal system, as evidenced by an increase in γ-H2AX expression in bone marrow cell DNA, loss of circulatory blood cells, elevation of serum cytokine concentration, and activation of nuclear factor-κB/inducible nitric oxide synthase, and an earlier onset of bacterial infection and sepsis after RCI than after RI was detected. Dysbiosis (imbalance of the gut microbiota) was observed. There remains a pressing need for both prophylactic countermeasures and therapeutic remedies to deal with RCI threats. Investigations of how RCI can affect this important network of communication between the gut microbiota and other organs, including the brain, lung, heart, liver, kidney, and skin, could lead to new and critical interventions and prevention strategies. This review provides an update on new RCI animal models, dynamic changes in cytokine expression, dysbiosis, as well as links between the gut microbiome and other organs after RCI. Full article

Substantial progress has been made in the development of radiation countermeasures, resulting in the recent approval of several mitigators; however, there has yet to be an approved prophylactic radioprotectant. Research on countermeasure performance in mixed neutron and gamma radiation fields has also been scarce. Fibroblast-stimulating lipopeptide (FSL-1) is a novel synthetic agonist for toll-like receptor 2/6. In previous studies, the administration of FSL-1 before and after gamma radiation significantly improved survival outcomes for mice through the activation of the NF-κB pathway. In the current study, we tested FSL-1’s radioprotective abilities in a mixed radiation field that models one produced by a nuclear detonation in 11–14-week-old C57BL/6 male and female mice. We demonstrate that a single dose of 1.5 mg/kg of FSL-1 administered 12 h prior to 65% neutron 35% gamma mixed-field (MF) irradiation enhances survival, accelerates recovery of hematopoietic cell and stem cell populations, reduces inflammation, and protects innate immune function in mice. FSL-1’s ability to recover blood and protect immune functions is important in countering the high rate of incidence of sepsis caused by MF radiation’s damaging effects. These results demonstrate that FSL-1 is a promising prophylactic countermeasure where exposure to MF radiation is anticipated. Full article

Acute radiation syndrome (ARS) occurs when hematopoietic or gastrointestinal cells are damaged by radiation exposure causing DNA damage to the bone marrow and gastrointestinal epithelial stem cell populations. In these highly proliferative cell types, DNA damage inhibits stem cell repopulation. In humans and animals, this inability to regenerate stem cells is lethal. Within this manuscript, several compounds, Amifostine, Captopril, Ciprofloxacin, PrC-210, 5-AED (5-androstene-3β,17β-diol), and 5-AET (5-androstene-3β,7β,17B-triol), are assessed for their ability to protect against ARS in an in vitro and/or in vivo setting. ARS was accomplished by irradiating mouse bone marrow cells or rat intestinal epithelial (IEC-6) cells in vitro with 4–8 Gy and in vivo by exposing Mus musculus to 7.3 Gy of whole-body irradiation. The primary endpoints of this study include cellular viability, DNA damage via γ-H2AX, colony formation, and overall survival at 30-days post-irradiation. In addition to evaluating the radioprotective performance of each compound, this study establishes a distinct set of in vitro assays to predict the overall efficacy of potential radioprotectors in an in vivo model of ARS. Furthermore, these results highlight the need for FDA-approved medical intervention to protect against ARS. Full article

Ionizing radiation is a health threat to many, including warfighters, radiological emergency responders, radiotherapy patients, and astronauts. Despite this, no FDA-approved prophylactic medical countermeasures exist to attenuate the symptoms that occur from radiation exposure. Manganese has recently been shown to be critical for radioresistance in a wide range of organisms. In this study, we designed a stringent feeding method to test the prophylactic effects of dietary manganese on Drosophila’s lifespan before exposure to acute irradiation. We found that male flies have substantially lower radioresistance than females, but feeding with low doses of MnCl₂ before acute irradiation exposure extends male survival to that of females. Whole animal electron paramagnetic resonance analyses showed males have lower amounts of high-symmetry manganese-metabolite antioxidant complexes (H-Mn) than females, but manganese supplementation increases H-Mn to female levels. Levels of mitochondrial free-radical scavenger manganese-superoxide-dismutase 2 (MnSOD2) did not increase after acute irradiation, nor did loss of MnSOD2 sensitize larvae to acute irradiation exposure. These data support that prophylactic manganese feeding is sufficient to increase survivorship in males subjected to acute irradiation, independent of MnSOD2 levels, indicating a role of antioxidant manganese-metabolite H-Mn complexes for radioprotection. Furthermore, this Drosophila feeding method could be used to identify additional radiation countermeasures. Full article

The emergence and re-emergence of pathogens with pandemic potential has been a persistent issue throughout history. Recent decades have seen significant outbreaks of zoonotic viruses from members of the Coronaviridae, Filoviridae, Paramyxoviridae, Flaviviridae, and Togaviridae families, resulting in widespread infections. The continual emergence of zoonotic viral pathogens and associated infections highlights the need for prevention strategies and effective treatments. Central to this effort is the availability of suitable animal models, which are essential for understanding pathogenesis and assessing transmission dynamics. These animals are also critical for evaluating the safety and efficacy of novel vaccines or therapeutics and are essential in facilitating regulatory approval of new products. Rapid development of animal models is an integral aspect of pandemic response and preparedness; however, their establishment is fraught by several rate-limiting steps, including selection of a suitable species, the logistical challenges associated with sharing and disseminating transgenic animals (e.g., the time-intensive nature of breeding and maintaining colonies), the availability of technical expertise, as well as ethical and regulatory approvals. A method for the rapid development of relevant animal models that has recently gained traction, in large part due to the COVID-19 pandemic, is the use of gene therapy vectors to express human viral receptors in readily accessible laboratory animals to enable virus infection and development of clinical disease. These models can be developed rapidly on any genetic background, making mechanistic studies and accelerated evaluation of novel countermeasures possible. In this review, we will discuss important considerations for the effective development of animal models using viral vector approaches and review the current vector-based animal models for studying viral pathogenesis and evaluating prophylactic and therapeutic strategies, with an emphasis on models of SARS-CoV-2 infection based on the vectorized expression of human angiotensin-converting enzyme 2. Full article

Animal models that are susceptible to SARS-CoV-2 infection and develop clinical signs like human COVID-19 are desired to understand viral pathogenesis and develop effective medical countermeasures. The golden Syrian hamster is important for the study of SARS-CoV-2 since hamsters are naturally susceptible to SARS-CoV-2. However, infected hamsters show only limited clinical disease and resolve infection quickly. In this study, we describe development of human angiotensin-converting enzyme 2 (hACE2) transgenic hamsters as a model for COVID-19. During development of the model for SARS-CoV-2, we observed that different hACE2 transgenic hamster founder lines varied in their susceptibility to SARS-CoV-2 lethal infection. The highly susceptible hACE2 founder lines F0F35 and F0M41 rapidly progress to severe infection and death within 6 days post-infection (p.i.). Clinical signs included lethargy, weight loss, dyspnea, and mortality. Lethality was observed in a viral dose-dependent manner with a lethal dose as low as 1 × 10^0.15 CCID₅₀. In addition, virus shedding from highly susceptible lines was detected in oropharyngeal swabs on days 2–5 p.i., and virus titers were observed at 10^5.5−6.5 CCID₅₀ in lung and brain tissue by day 4 p.i.. Histopathology revealed that infected hACE2-hamsters developed rhinitis, tracheitis, bronchointerstitial pneumonia, and encephalitis. Mortality in highly susceptible hACE2-hamsters can be attributed to neurologic disease with contributions from the accompanying respiratory disease. In contrast, virus challenge of animals from less susceptible founder lines, F0M44 and F0M51, resulted in only 0–20% mortality. To demonstrate utility of this SARS-CoV-2 infection model, we determined the protective effect of the TLR3 agonist polyinosinic-polycytidylic acid (Poly (I:C)). Prophylactic treatment with Poly (I:C) significantly improved survival in highly susceptible hACE2-hamsters. In summary, our studies demonstrate that hACE2 transgenic hamsters differ in their susceptibility to SARS-CoV-2 infection, based on the transgenic hamster founder line, and that prophylactic treatment with Poly (I:C) was protective in this COVID-19 model of highly susceptible hACE2-hamsters. Full article

Development of radiation medical countermeasures under the U.S. Food and Drug Administration Animal Rule requires the capability to translate an effective animal-to-human drug dose. One method of human dose translation is using a biomarker and determining drug doses that modulate the biomarker to the desired level. BIO 300 Oral Powder (BIO 300) is a prophylactic radiation medical countermeasure that is currently being developed following the Animal Rule. The present study aimed to identify biomarkers that can be used for human dose conversion by conducting transcriptomics of whole blood collected from BIO 300-treated CD2F1 mice in the presence and absence of total-body irradiation (TBI). Unirradiated mice were treated with vehicle or 50, 100, or 200 mg/kg BIO 300, and irradiated mice were treated with 200 mg/kg or BIO 300 or vehicle prior to TBI. Whole-blood samples were collected after the last dose of the drug and after irradiation. RNA sequencing demonstrated 100 and 200 mg/kg of BIO 300 doses caused significantly more differential gene expression at 48 h after drug dose compared to 50 mg/kg of BIO 300 (7648, 7680, and 55 significantly differently expressed genes, respectively). Interestingly, following TBI, there were no significantly differentially expressed genes between vehicle- and BIO 300-treated mice. Despite the lack of significant changes in gene expression, the transcriptomic profiles in both groups indicated differential changes in signaling pathways. Pathway analysis of the transcriptome profile from vehicle-treated/TBI mice revealed that many inflammatory signaling pathways were activated in these animals. Signaling pathways enriched in BIO 300-treated/TBI mice were involved in cellular stress and immune response and were predicted to be inhibited. In all, four signaling pathways of interest were identified that were differentially enriched in irradiated animals treated with BIO 300: pathogen-induced cytokine storm signaling, S100 family signaling, pulmonary fibrosis idiopathic signaling, and wound-healing signaling. These pathways should be explored to identify potential biomarkers of BIO 300 that can be used for human dose translation. Full article

Changes in the structure of bone can occur in space as an adaptive response to microgravity and on Earth due to the adaptive effects to exercise, to the aging of bone cells, or to prolonged disuse. Knowledge of cell-mediated bone remodeling on Earth informs our understanding of bone tissue changes in space and whether these skeletal changes might increase the risk for fractures or premature osteoporosis in astronauts. Comparisons of skeletal health between astronauts and aging humans, however, may be both informative and misleading. Astronauts are screened for a high level of physical fitness and health, are launched with high bone mineral densities, and perform exercise daily in space to combat skeletal atrophy as an adaptive response to reduced weight-bearing function, while the elderly display cellular and tissue pathology as a response to senescence and disuse. Current clinical testing for age-related bone change, applied to astronauts, may not be sufficient for fully understanding risks associated with rare and uniquely induced bone changes. This review aims to (i) highlight cellular analogies between spaceflight-induced and age-related bone loss, which could aid in predicting fractures, (ii) discuss why overreliance on terrestrial clinical approaches may miss potentially irreversible disruptions in trabecular bone microarchitecture induced by spaceflight, and (iii) detail how the cellular effects of the bisphosphonate class of drugs offer a prophylactic countermeasure for suppressing the elevated bone resorption characteristically observed during long-duration spaceflights. Thus the use of the bisphosphonate will help protect the bone from structural changes while in microgravity either along with exercise or alone when exercise is not performed, e.g. after an injury or illness. Full article

The development of safe, orally available, and effective prophylactic countermeasures to protect our warfighters is an unmet need because there is no such FDA-approved countermeasure available for use. Th 1-Propanethiol, 3-(methylamino)-2-((methylamino)methyl) (PrC-210), a synthetic small molecule, is a member of a new family of aminothiols designed to reduce toxicity while scavenging reactive oxygen species (ROS). Our study investigated the protective role of a single oral administration of PrC-210 against radiation-induced hematopoietic and intestinal injury in mice. Pre-treatment with PrC-210 significantly improved the survival of mice exposed to a lethal dose of radiation. Our findings indicated that the radioprotective properties of PrC-210 are achieved by accelerating the recovery of the hematopoietic system, stimulating bone marrow progenitor cells, and ameliorating additional biomarkers of hematopoietic injury. PrC-210 pre-treatment reduced intestinal injury in mice exposed to a lethal dose of radiation by restoring jejunal crypts and villi, reducing translocation of bacteria to the spleen, maintaining citrulline levels, and reducing the sepsis marker serum amyloid A (SAA) in serum. Finally, PrC-210 pre-treatment led to a significant reduction (~10 fold) of Nos2 expression (inducible nitric oxide) in the spleen and decreased oxidative stress by enhancing the antioxidant defense system. These data support the further development of PrC-210 to receive approval from the FDA to protect warfighters and first responders from exposure to the harmful effects of ionizing radiation. Full article

Nigeria experiences annual outbreaks of Lassa fever (LF) with high case numbers. At least three clades of Lassa virus (LASV) have been documented in Nigeria, though recent outbreaks are most often associated with clade II or clade III viruses. Using a recently isolated clade III LASV from a case of LF in Nigeria in 2018, we developed and characterized a guinea pig adapted virus capable of causing lethal disease in commercially available Hartley guinea pigs. Uniform lethality was observed after four passages of the virus and was associated with only two dominant genomic changes. The adapted virus was highly virulent with a median lethal dose of 10 median tissue culture infectious doses. Disease was characterized by several hallmarks of LF in similar models including high fever, thrombocytopenia, coagulation disorders, and increased inflammatory immune mediators. High viral loads were noted in all solid organ specimens analyzed. Histological abnormalities were most striking in the lungs and livers of terminal animals and included interstitial inflammation, edema, and steatosis. Overall, this model represents a convenient small animal model for a clade III Nigeria LASV with which evaluation of specific prophylactic vaccines and medical countermeasures can be conducted. Full article

We carried out a molecular biological analysis of extended-spectrum β-lactamase (ESBL)-producing E. coli strains and their sensitivity to flomoxef (FMOX). Sequence type (ST) analysis by multilocus sequence typing (MLST) and classification of ESBL genotypes by multiplex PCR were performed on ESBL-producing E. coli strains isolated from urine samples collected from patients treated at our institution between 2008 and 2018. These sequences were compared with results for antimicrobial drug susceptibility determined using a micro-liquid dilution method. We also analyzed cases treated with FMOX at our institution to examine its clinical efficacy. Of the 911 E. coli strains identified, 158 (17.3%) were ESBL-producing. Of these, 67.7% (107/158) were strain ST-131 in ST analysis. Nearly all (154/158; 97.5%) were CTX-M genotypes, with M-14 and M-27 predominating. The isolated strains were sensitive to FMOX in drug susceptibility tests. Among the patient samples, 33 cases received FMOX, and of these, 5 had ESBL-producing E. coli. Among these five cases, three received FMOX for surgical prophylaxis as urinary carriers of ESBL-producing E. coli, and postoperative infections were prevented in all three patients. The other two patients received FMOX treatment for urinary tract infections. FMOX treatment was successful for one, and the other was switched to carbapenem. Our results suggest that FMOX has efficacy for perioperative prophylactic administration in urologic surgery involving carriers of ESBL-producing bacteria and for therapeutic administration for urinary tract infections. Use of FMOX avoids over-reliance on carbapenems or β-lactamase inhibitors and thus is an effective antimicrobial countermeasure. Full article

The frequent emergence of SARS-CoV-2 variants thwarts the prophylactic and therapeutic countermeasures confronting COVID-19. Among them, the Delta variant attracts widespread attention due to its high pathogenicity and fatality rate compared with other variants. However, with the emergence of new variants, studies on Delta variants have been gradually weakened and ignored. In this study, a replication-competent recombinant virus carrying the S protein of the SARS-CoV-2 Delta variant was established based on the vesicular stomatitis virus (VSV), which presented a safe alternative model for studying the Delta variant. The recombinant virus showed a replication advantage in Vero E6 cells, and the viral titers reach 10^7.3 TCID₅₀/mL at 36 h post-inoculation. In the VSV-vectored recombinant platform, the spike proteins of the Delta variant mediated higher fusion activity and syncytium formation than the wild-type strain. Notably, the recombinant virus was avirulent in BALB/c mice, Syrian hamsters, 3-day ICR suckling mice, and IFNAR/GR^−/− mice. It induced protective neutralizing antibodies in rodents, and protected the Syrian hamsters against the SARS-CoV-2 Delta variant infection. Meanwhile, the eGFP reporter of recombinant virus enabled the visual assay of neutralizing antibodies. Therefore, the recombinant virus could be a safe and convenient surrogate tool for authentic SARS-CoV-2. This efficient and reliable model has significant potential for research on viral-host interactions, epidemiological investigation of serum-neutralizing antibodies, and vaccine development. Full article