Caroline Hadley

A preclinical rodent model of radiation-induced lung injury for medical countermeasure screening in accordance with the FDA animal rule.

Abstract The purpose of preclinical murine model development is to establish that the pathophysiological outcome of the rodent model of radiation-induced lung injury is sufficiently representative of the anticipated pulmonary response in the human population. This objective is based on concerns that the C57BL/6J strain may not be the most appropriate preclinical model of lethal radiation lung injury in humans. In this study, the authors assessed this issue by evaluating the relationship between morbidity (pulmonary function, histopathologic damage) and mortality among three strains of mice: C57BL/6J, CBA/J, and C57L/J. These different strains display variations in latency and phenotypic expression of radiation-induced lung damage. By comparing the response of each strain to the human pulmonary response, an appropriate animal model(s) of human radiation-induced pulmonary injury was established. Observations in the C57L/J and CBA/J murine models can be extrapolated to the human lung for evaluation of the mechanisms of action of radiation as well as future efficacy testing and approving agents that fall under the “Animal Rule” of the U.S. Food and Drug Administration (FDA) (21 CFR Parts 314 and 601).

Characterization of the dose response relationship for lung injury following acute radiation exposure in three well-established murine strains: developing an interspecies bridge to link animal models with human lung.

AbstractApproval of radiation countermeasures through the FDA Animal Rule requires pivotal efficacy screening in one or more species that are expected to react with a response similar to humans (21 C.F.R. § 314.610, drugs; § 601.91, biologics). Animal models used in screening studies should reflect the dose response relationship (DRR), clinical presentation, and pathogenesis of lung injury in humans. Over the past 5 y, the authors have characterized systematically the temporal onset, dose-response relationship (DRR), and pathologic outcomes associated with acute, high dose radiation exposure in three diverse mouse strains. In these studies, C57L/J, CBA/J, and C57BL/6J mice received wide field irradiation to the whole thorax with shielding of the head, abdomen, and forelimbs. Doses were delivered at a rate of 69 cGy min−1 using an x-ray source operated at 320 kVp with half-value layer (HVL) of 1 mm Cu. For all strains, radiation dose was associated significantly with 180 d mortality (p < 0.0001). The lethal dose for 50% of animals within the first 180 d (LD50/180) was 11.35 Gy (95% CI 11.1–11.6 Gy) for C57L/J mice, 14.17 Gy (95% CI 13.9–14.5 Gy) for CBA/J mice, and 14.10 Gy (95% CI 12.2–16.4 Gy) for C57BL/6J mice. The LD50/180 in the C57L/J strain was most closely analogous to the DRR for clinical incidence of pneumonitis in non-human primates (10.28 Gy; 95% CI 9.9–10.7 Gy) and humans (10.60 Gy; 95% CI 9.9–12.1 Gy). Furthermore, in the C57L/J strain, there was no gender-specific difference in DRR (p = 0.5578). The reliability of the murine models is demonstrated by the reproducibility of the dose-response and consistency of disease presentation across studies.Health Phys. 106(1):000-000; 2014

Temporal expression of hypoxia-regulated genes is associated with early changes in redox status in irradiated lung

The development of normal lung tissue toxicity after radiation exposure results from multiple changes in cell signaling and communication initiated at the time of the ionizing event. The onset of gross pulmonary injury is preceded by tissue hypoxia and chronic oxidative stress. We have previously shown that development of debilitating lung injury can be mitigated or prevented by administration of AEOL10150, a potent catalytic antioxidant, 24h after radiation. This suggests that hypoxia-mediated signaling pathways may play a role in late radiation injury, but the exact mechanism remains unclear. The purpose of this study was to evaluate changes in the temporal expression of hypoxia-associated genes in irradiated mouse lung and determine whether AEOL10150 alters expression of these genes. A focused oligo array was used to establish a hypoxia-associated gene expression signature for lung tissue from sham-irradiated or irradiated mice treated with or without AEOL10150. Results were further verified by RT-PCR. Forty-four genes associated with metabolism, cell growth, apoptosis, inflammation, oxidative stress, and extracellular matrix synthesis were upregulated after radiation. Elevated expression of 31 of these genes was attenuated in animals treated with AEOL10150, suggesting that expression of a number of hypoxia-associated genes is regulated by early development of oxidative stress after radiation. Genes identified herein could provide insight into the role of hypoxic signaling in radiation lung injury, suggesting novel therapeutic targets, as well as clues to the mechanism by which AEOL10150 confers pulmonary radioprotection.

Osteosarcoma of the cranial vault and skull base in pediatric patients

Cranial osteosarcoma is very rare in children, rendering the development of optimal treatment algorithms challenging. The authors present 3 cases of pediatric cranial osteosarcoma: a primary calvarial tumor, a cranial metastasis, and a primary osteosarcoma of the cranial base. A review of the literature demonstrates significant variation in the management of cranial osteosarcomas and the outcome for patients with these tumors. This series and literature review is presented to improve the understanding of pediatric cranial osteosarcoma and to reinforce the importance of maximal resection in optimizing outcome.

Development and dosimetry of a small animal lung irradiation platform.

Abstract Advances in large scale screening of medical countermeasures for radiation-induced normal tissue toxicity are currently hampered by animal irradiation paradigms that are both inefficient and highly variable among institutions. Here, a novel high-throughput small animal irradiation platform is introduced for use in orthovoltage small animal irradiators. Radiochromic film and metal oxide semiconductor field effect transistor detectors were used to examine several parameters, including 2D field uniformity, dose rate consistency, and shielding transmission. The authors posit that this setup will improve efficiency of drug screens by allowing for simultaneous targeted irradiation of multiple animals to improve efficiency within a single institution. Additionally, they suggest that measurement of the described parameters in all centers conducting countermeasure studies will improve the translatability of findings among institutions. The use of tissue equivalent phantoms in performing dosimetry measurements for small animal irradiation experiments was also investigated. Though these phantoms are commonly used in dosimetry, the authors recorded a significant difference in both the entrance and target tissue dose rates between euthanized rats and mice with implanted detectors and the corresponding phantom measurement. This suggests that measurements using these phantoms may not provide accurate dosimetry for in vivo experiments. Based on these measurements, the authors propose that this small animal irradiation platform can increase the capacity of animal studies by allowing for more efficient animal irradiation. They also suggest that researchers fully characterize the parameters of whatever radiation setup is in use in order to facilitate better comparison among institutions.

Factors influencing outcomes of the treatment of positional plagiocephaly in infants: a 7-year experience

OBJECTIVE Following institution of the Back to Sleep Campaign, the incidence of sudden infant death syndrome decreased while the prevalence of positional skull deformation increased dramatically. The management of positional deformity is controversial, and treatment recommendations and outcomes reporting are variable. The authors reviewed their institutional experience (2008-2014) with the treatment of positional plagiocephaly to explore factors associated with measured improvement. METHODS A retrospective chart review was conducted with risk factors and treatment for positional head shape deformity recorded. Univariate and multivariate analyses were used to assess the impact of these variables on the change in measured oblique diagonal difference (ODD) on head shape surface scanning pre- and posttreatment. RESULTS A total of 991 infants aged less than 1 year were evaluated for cranial positional deformity in a dedicated clinical program. The most common deformity was occipital plagiocephaly (69.5%), followed by occipital brachycephaly (18.4%) or a combination of both deformities (12.1%). Recommended treatment included repositioning (RP), physical therapy (PT) if indicated, or orthotic treatment with a customized cranial orthosis (CO) according to an age- and risk factor-dependent algorithm that the authors developed for this clinic. Of the 991 eligible patients, 884 returned for at least 1 follow-up appointment. A total of 552 patients were followed to completion of their treatment and had a full set of records for analysis: these patients had pre- and posttreatment 2D surface scanner evaluations. The average presenting age was 6.2 months (corrected for prematurity for treatment considerations). Of the 991 patients, 543 (54.8%) had RP or PT as first recommended treatment. Of these 543 patients, 137 (25.2%) transitioned to helmet therapy after the condition did not improve over 4-8 weeks. In the remaining cases, RP/PT had already failed before the patients were seen in this program, and the starting treatment recommendation was CO. At the end of treatment, the measured improvements in ODD were 36.7%, 33.5%, and 15.1% for patients receiving CO, RP/PT/CO, and RP/PT, respectively. Univariate analysis showed that sex, race, insurance, diagnosis, sleep position preference, torticollis history, and multiple gestation were not significantly associated with magnitude of ODD change during treatment. On multivariate analysis, corrected age at presentation and type of treatment received were significantly associated with magnitude of ODD change. Orthotic treatment corresponded with the largest ODD change, while the RP/PT group had the least change in ODD. Earlier age at presentation corresponded with larger ODD change. CONCLUSIONS Earlier age at presentation and type of treatment impact the degree of measured deformational head shape correction in positional plagiocephaly. This retrospective study suggests that treatment with a custom CO can result in more improvement in objective measurements of head shape.

Molecular Mechanisms of Radiation Induced Injury

Radiation-induced normal tissue injury represents a major impediment to the successful achievement of the desired clinical outcome from radiation therapy (RT) for cancer patients; usually improved local control, reduced risk for disease reoccurrence, and increased survival. Complications associated with RT can result in diminished quality of life and carries the potential for severe debilitating disease. The development of normal tissue protectors/radiomitigators is dependent on improved understanding of the molecular mechanisms associated with the development of acute and long-term RT-induced tissue toxicity. The following chapter provides a comprehensive review of the current state of knowledge with respect to those mechanisms underlying radiation-induced normal tissue pathologies. Future scientific endeavors will build upon this groundwork to delve deeper into the mechanistic understanding of disease onset and progression and develop new agents that can be translated from bench to bedside to reduce the risk for RT-induced complications.

Hypo-CpG methylation controls PTEN expression and cell apoptosis in irradiated lung

Abstract Purpose: The current study was designed to address our hypothesis that oxidative stress secondary to the ionizing event upregulates phosphatase and tensin homolog (PTEN) mRNA and protein in the lungs of C57BL/6J mice through oxidative DNA damage resulting in CpG hypomethylation in the PTEN promoter. Methods: Fibrosis-prone C57BL/6J mice were exposed to 0 or 15 Gy of 320 kVp X-rays to the whole thorax. Lung tissue was serially harvested at time points between one day and six months postirradiation. Tissue levels of PTEN mRNA, total protein, and phosphorylated PTEN, as well as CpG methylation of the PTEN promoter, expression of DNA methyltransferases 1 (Dnmt1) and 3a (Dnmt3a), NADPH oxidase 4 (Nox4) protein expression, and DNA damage levels were measured. The induction of DNA damage and global methylation changes were also examined in hydrogen peroxide (H2O2)-treated human umbilical vein endothelial cells (HUVECs) and human bronchial epithelial cells in vitro. Results: These experiments demonstrate that PTEN mRNA and protein, Nox4 protein, and DNA damage levels increase continuously from one day to six months following radiation exposure. Elevated PTEN transcription and translation are likely the result of the observed decrease in CpG methylation of the PTEN promoter region. This finding is not consistent with the observed increase in Dnmt1 and Dnmt3a protein expression, implicating an alternative mechanism as the driving force behind hypomethylation. In vitro results provide evidence that H2O2 can induce DNA damage and affect DNA methylation status. The Mn porphyrin-based superoxide dismutase (SOD) mimic MnTnHEx-2-PyP5+ exhibited partial rescue from radiation-induced hypomethylation. Conclusions: Taken together, these data suggest that reactive oxygen species (ROS)-induced DNA damage results in hypomethylation of the PTEN promoter, upregulation of PTEN mRNA and protein, and a subsequent increase in apoptosis in irradiated lung tissue.

Congenital neurocristic tumor presenting as an isolated calvarial defect in an infant: case report.

In infants, the presence of a cranial defect may be due to a variety of traumatic, inflammatory, neoplastic, and congenital abnormalities. Differentiation between these possible etiologies is facilitated by clinical presentation, patient history, and physical examination. Congenital cutaneous neural crest-derived lesions are unlikely to be considered in a patient presenting with an asymptomatic cranial defect without overlying mass or skin pigmentation. The authors present an unusual case of a 2-month-old infant with an asymptomatic calvarial defect with normal overlying skin. Pathology of the excised tissue showed features consistent with a congenital neurocristic tumor: a pigmented, neural crest-derived hamartomatous tumor that typically presents as a melanotic skin lesion.

Pediatric pedicle screw (In)accuracy based on postoperative computed tomography

Though pedicle screws are widely used in spinal stabilization, studies evaluating the variables affecting placement accuracy and effects of accuracy on outcome are limited. Using computed tomography (CT), we evaluated the accuracy of pedicle screw placement in pediatric and transitional patient populations. We evaluated screw placement in a series of 276 thoracic, lumbar, and sacral pedicle screws implanted in 41 patients with the assistance of fluoroscopy by a single surgeon at a single institution from September 1, 2007 to December 31, 2012. Postoperative CT was performed and each screw was graded based on relation to neurologic, osseous, and intra thoracic and intra-abdominal landmarks by an independent neuro radiologist: Grade I, entirely intra pedicular; Grade II, violates lateral pedicle but screw tip entirely within the vertebral body; Grade III, tip penetrates the anterior or lateral vertebral body; Grade IV, breaches medial or inferior pedicle; and Grade V, violates pedicle or vertebral body and threatens spinal cord, nerve root, or great vessels, requires immediate revision or removal. The accuracy rate (Grades I and II) was lower than expected (76.8%). Screw misplacements (Grades III, IV, and V) were numerous (23.2%), although the overall complication rate remained low. There was no statistically significant difference in pedicle screw accuracy as a function of surgeon experience, patient age, or patient diagnosis. This suggests the need for advanced intraoperative imaging, such as neuronavigation or CT, to aid placement of spinal instrumentation in the pediatric and transitional patient population. While postoperative CT should be considered gold standard for evaluating pedicle screw placement, further study is warranted to evaluate overall accuracy and assess the need for more extensive intraoperative imaging to improve accuracy.