Effect of Radiation on DCE-MRI Pharmacokinetic Parameters in a Rabbit Model of Compromised Maxillofacial Wound Healing: A Pilot Study.

PURPOSE: Osteoradionecrosis (ORN), a potentially debilitating complication of maxillofacial radiation, continues to present a challenging clinical scenario, with limited treatment options that often fail. Translational animal models that can accurately mimic the human characteristics of the condition are lacking. In the present pilot study, we aimed to characterize the effects of radiation on the dynamic contrast-enhanced magnetic resonance imaging (DCE-MRI) pharmacokinetic parameters in a rabbit model of compromised maxillofacial wound healing to determine its potential as a translational model of ORN. MATERIALS AND METHODS: An experimental group underwent fractionated radiation of the mandible totaling 36 Gy. At 4 weeks after irradiation, the experimental and control groups (n = 8 rabbits each) underwent a surgical procedure to create a critical size defect in the mandibular bone. DCE-MRI scans were acquired 1 week after arrival (baseline; time point 1), 4 weeks after completion of irradiation in the experimental group (just before surgery, time point 2), and 4 weeks after surgery (time point 3). RESULTS: No differences in the analyzed DCE-MRI parameters were noted within the experimental or control group between the baseline values (time point 1) and those after irradiation (time point 2). The whole blood volume fraction (vb) in the experimental group was increased compared with that in the control group after irradiation (time point 2; P < .05). After surgery (time point 3), both the forward flux rate of contrast from blood plasma and the extracellular extravascular space and the vb were increased in the control group compared with the experimental group (P < .05). CONCLUSIONS: The results of the present study suggest that DCE-MRI of a rabbit model of compromised maxillofacial wound healing could reflect the DCE-MRI characteristics of human patients with ORN and those at risk of developing the condition. Future studies will focus on further characterization of this rabbit model as a translational preclinical model of ORN.

A Design-Based Stereologic Method to Quantify the Tissue Changes Associated with a Novel Drug-Eluting Tracheobronchial Stent.

BACKGROUND: Granulation tissue is a common complication of airway stenting, but no published methods can quantify the volume and type of tissue that develops. OBJECTIVE: To use design-based stereology to quantify changes in tissue volume and type associated with airway stenting. METHODS: We compared drug-eluting stents (DES) filled with gendine to standard silicone stents in pigs in an assessor-blinded randomized trial. Tracheal stents were placed via rigid bronchoscopy. After 1 month, animals were euthanized and necropsies were performed. Antimicrobial effects of the DES were assessed in trachea tissue samples, on the DES surface, and with residual gel from the DES reservoir. Tracheal thickness was measured using orthogonal intercepts. Design-based stereology was used to quantify the volume density of tissues using a point-counting method. The volume of each tissue was normalized to cartilage volume, which is unaffected by stenting. RESULTS: Pigs were randomized to DES (n = 36) or control stents (n = 9). The drug was successfully eluted from the DES, and the stent surface showed antibacterial activity. DES and controls did not differ in tissue microbiology, tracheal thickness, or granulation tissue volume. Compared to nonstented controls, stented airways demonstrated a 110% increase in soft-tissue volume (p = 0.005). Submucosal connective tissue (118%; p < 0.0001), epithelium (70%; p < 0.0001), submucosal glands (47%; p = 0.001), and smooth muscle (41%; p < 0.0001) increased in volume. CONCLUSION: Stenting doubles the volume of soft tissue in the trachea. Design-based stereology can quantify the tissue changes associated with airway stenting.

Efficacy of sustained delivery of GC-1 from a Nanofluidic system in a spontaneously obese non-human primate: a case study.

With nearly 40% of U.S. adults obese, and childhood and adolescent rates rising, obesity and associated comorbidities are serious public health concerns with massive societal costs. Often, lifestyle interventions do not offer sufficient weight loss to improve health, requiring surgery and medications as adjunct management strategies. Here, we present a 4-month case study in which the sustained, low-dose, and constant administration of the thyroid receptor ß selective agonist GC-1 (sobetirome) from a novel nanochannel membrane implant was assessed in an obese, pre-diabetic rhesus macaque. Dramatic loss of white adipose tissue in the abdomen from 36 to 18% was observed via magnetic resonance imaging in conjunction with normalized serum insulin and glycemia, with no signs of cardiotoxicity shown. The non-human primate study highlights sustained low-dose delivery of GC-1 from our minimally invasive subcutaneous implant as a valuable approach to induce weight loss and manage obesity and comorbidities, including type 2 diabetes.

Safety and Efficacy of an Absorbable Filter in the Inferior Vena Cava to Prevent Pulmonary Embolism in Swine.

Purpose To evaluate the immediate and long-term safety as well as thrombus-capturing efficacy for 5 weeks after implantation of an absorbable inferior vena cava (IVC) filter in a swine model. Materials and Methods This study was approved by the institutional animal care and use committee. Eleven absorbable IVC filters made from polydioxanone suture were deployed via a catheter in the IVC of 11 swine. Filters remained in situ for 2 weeks (n = 2), 5 weeks (n = 2), 12 weeks (n = 2), 24 weeks (n = 2), and 32 weeks (n = 3). Autologous thrombus was administered from below the filter in seven swine from 0 to 35 days after filter placement. Fluoroscopy and computed tomography follow-up was performed after filter deployment from weeks 1-6 (weekly), weeks 7-20 (biweekly), and weeks 21-32 (monthly). The infrarenal IVC, lungs, heart, liver, kidneys, and spleen were harvested at necropsy. Continuous variables were evaluated with a Student t test. Results There was no evidence of IVC thrombosis, device migration, caval penetration, or pulmonary embolism. Gross pathologic analysis showed gradual device resorption until 32 weeks after deployment. Histologic assessment demonstrated neointimal hyperplasia around the IVC filter within 2 weeks after IVC filter deployment with residual microscopic fragments of polydioxanone suture within the caval wall at 32 weeks. Each iatrogenic-administered thrombus was successfully captured by the filter until resorbed (range, 1-4 weeks). Conclusion An absorbable IVC filter can be safely deployed in swine and resorbs gradually over the 32-week testing period. The device is effective for the prevention of pulmonary embolism for at least 5 weeks after placement in swine. © RSNA, 2017.

Clarifying the Ethics and Oversight of Chimeric Research.

This article is the lead piece in a special report that presents the results of a bioethical investigation into chimeric research, which involves the insertion of human cells into nonhuman animals and nonhuman animal embryos, including into their brains. Rapid scientific developments in this field may advance knowledge and could lead to new therapies for humans. They also reveal the conceptual, ethical, and procedural limitations of existing ethics guidance for human-nonhuman chimeric research. Led by bioethics researchers working closely with an interdisciplinary work group, the investigation focused on generating conceptual clarity and identifying improvements to governance approaches, with the goal of helping scholars, funders, scientists, institutional leaders, and oversight bodies (embryonic stem cell research oversight [ESCRO] committees and institutional animal care and use committees [IACUCs]) deliver principled and trustworthy oversight of this area of science. The article, which focuses on human-nonhuman animal chimeric research that is stem cell based, identifies key ethical issues in and offers ten recommendations regarding the ethics and oversight of this research. Turning from bioethics' previous focus on human-centered questions about the ethics of "humanization" and this research's potential impact on concepts like human dignity, this article emphasizes the importance of nonhuman animal welfare concerns in chimeric research and argues for less-siloed governance and oversight and more-comprehensive public communication.

ISSCR guidelines for the transfer of human pluripotent stem cells and their direct derivatives into animal hosts.

The newly revised 2021 ISSCR Guidelines for Stem Cell Research and Clinical Translation includes scientific and ethical guidance for the transfer of human pluripotent stem cells and their direct derivatives into animal models. In this white paper, the ISSCR subcommittee that drafted these guidelines for research involving the use of nonhuman embryos and postnatal animals explains and summarizes their recommendations.

Development and Characterization of a Rabbit Model of Compromised Maxillofacial Wound Healing.

IMPACT STATEMENT: Maxillofacial defects often present the clinical challenge of a compromised wound bed. Preclinical evaluation of tissue engineering techniques developed to facilitate healing and reconstruction typically involves animal models with ideal wound beds. The healthy wound bed scenario does not fully mimic the complex clinical environment in patients, which can lead to technology failure when translating from preclinical in vivo research to clinical use. The reported preclinical animal model of compromised wound healing enables investigation of tissue engineering technologies in a more clinically relevant scenario, potentially fostering translation of promising results in preclinical research to patients.

Lymphocytes upregulate CD36 in adipose tissue and liver.

CD36 is a multifunctional scavenger receptor and lipid transporter implicated in metabolic and inflammatory pathologies, as well as cancer progression. CD36 is known to be expressed by adipocytes and monocytes/macrophages, but its expression by T cells is not clearly established. We found that CD4 and CD8 T cells in adipose tissue and liver of humans, monkeys, and mice upregulated CD36 expression (ranging from ~5-40% CD36+), whereas little to no CD36 was expressed by T cells in blood, spleen, and lymph nodes. CD36 was expressed predominantly by resting CD38-, HLA.DR-, and PD-1- adipose tissue T cells in monkeys, and increased during high-fat feeding in mice. Adipose tissue and liver promote a distinct phenotype in resident T cells characterized by CD36 upregulation.

Bronchoscopic Laser Interstitial Thermal Therapy: An Experimental Study in Normal Porcine Lung Parenchyma.

BACKGROUND: Population aging and lung cancer screening strategies may lead to an increase in detection of early-stage lung cancer in medical inoperable patients. Recent advances in peripheral bronchoscopy have made it a suitable platform for ablation of small peripheral tumors. METHODS: We investigated the tissue-ablative effect of a diode laser bronchoscopically applied by a laser delivery fiber (LDF) with wide aperture on porcine lung parenchyma. Laser was tested ex vivo and in vivo to identify the most effective power settings and LDF. Chest computed tomography (CT) were obtained immediately after ablation and after 3 days of observation. At day 3, necropsy was performed. RESULTS: On the basis of our ex vivo and in vivo experiments, we selected the round-tip LDF to be activated at 25 W for 20 seconds. Ten ablations were performed in 5 pigs. One ablation resulted in a pneumothorax requiring aspiration. All animals remained stable for 72 hours. CT findings at days 1 and 3 showed an area of cavitation surrounded by consolidation and ground glass. Median size of CT findings (long axis) was 26 mm (range, 24 to 38) at day 1, and 34 mm (range, 30 to 44) at day 3. Necropsy showed an area of central char measuring from 0.8×0.7×0.9 cm to 2.4×3.5×1.2 cm, surrounded by a gray-brown to dark red area. On histology, variable degrees of necrosis were evident around the charred areas. CONCLUSION: Bronchoscopic laser interstitial thermal therapy can achieve relatively large areas of ablation of normal lung parenchyma with a low rate of periprocedural complications.

Diaphragmatic Hernia of the Stomach with Gastric Rupture in a Domestic Pig.

A 5.5-mo-old castrated, male Red Duroc pig presented acutely with depression and abdominal pain 9 d after an altercation with another pig. A CT examination indicated right pneumothorax and herniation of the stomach into the thoracic cavity. Due to a poor prognosis, the pig was euthanized. A necropsy and gross examination revealed a tear of the diaphragmatic muscle in the region of the esophageal hiatus through which the stomach was displaced into the right side of the thoracic cavity. In addition, the herniated stomach had a rupture of the stomach wall through which the gastric mucosa was everted and exposed into the right thoracic cavity. The right thoracic cavity had acute fibrinous pleuritis, and the right lung was collapsed. CT scans performed every 1 to 2 wk for 2 mo prior to the pig's death did not reveal any abnormalities in the diaphragm. Trauma was considered the most likely cause of the diaphragmatic tear and subsequent herniation and rupture of the stomach.

A simple, inexpensive method to minimize floor-drain obstructions while supporting environmental enrichment in primate facilities.

An important component of nonhuman primate environmental enrichment programs is affording the animals the opportunity to manipulate objects. Although these objects and various bulky food items enrich the quality of life for nonhuman primates, they complicate the duties of facility maintenance personnel. A prime example of these sometimes costly complications is a seemingly never-ending series of floor drain obstructions. We devised a simple, inexpensive modified drain cover that prevents large items from entering the drain. The total cost of materials for this device was 1.12 dollars, and it required only 15 min of labor for assembly. The design and implementation of this modified drain cover illustrate why the interaction between physical-plant personnel and animal-care personnel is key to the operation of a successful animal care and use program and proper maintenance of laboratory animal facilities.

Perineal swellings in two strains of mice.

Seven adult male mice of two different strains and from two different animal housing facilities were submitted for necropsy to evaluate unilateral or bilateral swellings in the ventral perineal area. On dissection, the swellings were oval to spherical cystic structures located near the base of the penis. Striated muscle and a delicate stroma encapsulated all cystic structures. Cysts were firm, tan, and filled with clear, yellow fluid, or were softer and filled with white, amorphous, marbled material and a smaller amount of clear, yellow fluid. Evaluation of the cysts led us to a diagnosis of cystic bulbourethral (or Cowper s) glands. Possible causes and the incidence of this condition in other species are discussed.

Demodex musculi in the Skin of Transgenic Mice.

Although infestations by a number of Demodex mite species have been described in mice, the occurrence of Demodex musculi infestation was last reported by Hirst in 1917. This communication describes the occurrence of D. musculi infestation in two lines of transgenic mice and their F1-hybrid offspring. We first found the Demodex mite in mouse hair samples collected during efficacy screenings in an ongoing ectoparasite treatment trial for the fur mite Radfordia affinis. An investigation was undertaken to determine the extent of the Demodex infestation within the facility and the original source of the parasite. D. musculi was found in three of the four mouse genotypes present in the index room and in one of these genotypes in two other rooms. The mite was not found in sentinel mice, other strains, or stocks within the facility. The mites were more easily recovered from the immunodeficient B6,CBA-TgN(CD3E)26Cpt transgenic (Tg) and the hybrid double-Tg (B6,CBA-TgN(CD3E)26Cpt x B6,SENCARB-TgN(pk5prad1)7111Sprd)F1 mice than from the B6,SENCARB-TgN(pk5prad1)7111Sprd Tg mouse, which is believed to be immunocompetent despite its thymic abnormalities. Histopathologic examination showed D. musculi superficially in hair follicles but not in the preputial or clitoral gland or in serial sections of the head, eyelids, or ears, the locations favored by other mouse demodicids. Physical and microscopic examination revealed no dermatitis. The immune deficiency in the B6,CBA-TgN(CD3E)26Cpt mouse probably provided the permissive host conditions that contributed to the proliferation and subsequent detection of the Demodex. Preliminary transmission experiments conducted with other immunologic mutant mice and our sentinel strain demonstrated variation in mite transfer and in either detection or maintenance of infestation when na ve mice were housed with those carrying D. musculi. The original source of D. musculi was not conclusively identified, but this parasite appears to be of low pathogenicity in the examined genotypes.