Hamsters Expressing Human Angiotensin-Converting Enzyme 2 Develop Severe Disease following Exposure to SARS-CoV-2.

The rapid emergence of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) has created a global health emergency. While most human disease is mild to moderate, some infections lead to a severe disease characterized by acute respiratory distress, hypoxia, anosmia, ageusia, and, in some instances, neurological involvement. Small-animal models reproducing severe disease, including neurological sequela, are needed to characterize the pathophysiological mechanism(s) of disease and to identify medical countermeasures. Transgenic mice expressing the human angiotensin-converting enzyme 2 (hACE2) viral receptor under the control of the K18 promoter develop severe and lethal respiratory disease subsequent to SARS-CoV-2 intranasal challenge when high viral doses are used. Here, we report on SARS-CoV-2 infection of hamsters engineered to express the hACE2 receptor under the control of the K18 promoter. K18-hACE2 hamsters infected with a relatively low dose of 100 or 1,000 PFU of SARS-CoV-2 developed a severe and lethal disease, with most animals succumbing by day 5 postinfection. Hamsters developed severe lesions and inflammation within the upper and lower respiratory system, including infection of the nasal cavities causing marked destruction of the olfactory epithelium as well as severe bronchopneumonia that extended deep into the alveoli. Additionally, SARS-CoV-2 infection spread to the central nervous system (CNS), including the brain stem and spinal cord. Wild-type (WT) hamsters naturally support SARS-CoV-2 infection, with the primary lesions present in the respiratory tract and nasal cavity. Overall, infection in the K18-hACE2 hamsters is more extensive than that in WT hamsters, with more CNS involvement and a lethal outcome. These findings demonstrate the K18-hACE2 hamster model will be valuable for studying SARS-CoV-2. IMPORTANCE The rapid emergence of SARS-CoV-2 has created a global health emergency. While most human SARS-CoV-2 disease is mild, some people develop severe, life-threatening disease. Small-animal models mimicking the severe aspects of human disease are needed to more clearly understand the pathophysiological processes driving this progression. Here, we studied SARS-CoV-2 infection in hamsters engineered to express the human angiotensin-converting enzyme 2 viral receptor under the control of the K18 promoter. SARS-CoV-2 produces a severe and lethal infection in transgenic hamsters that mirrors the most severe aspects of COVID-19 in humans, including respiratory and neurological injury. In contrast to other animal systems, hamsters manifest disease with levels of input virus more consistent with natural human infection. This system will be useful for the study of SARS-CoV-2 disease and the development of drugs targeting this virus.

Human convalescent plasma protects K18-hACE2 mice against severe respiratory disease.

SARS-CoV-2 is the causative agent of COVID-19 and human infections have resulted in a global health emergency. Small animal models that reproduce key elements of SARS-CoV-2 human infections are needed to rigorously screen candidate drugs to mitigate severe disease and prevent the spread of SARS-CoV-2. We and others have reported that transgenic mice expressing the human angiotensin-converting enzyme 2 (hACE2) viral receptor under the control of the Keratin 18 (K18) promoter develop severe and lethal respiratory disease subsequent to SARS-CoV-2 intranasal challenge. Here we report that some infected mice that survive challenge have residual pulmonary damages and persistent brain infection on day 28 post-infection despite the presence of anti-SARS-COV-2 neutralizing antibodies. Because of the hypersensitivity of K18-hACE2 mice to SARS-CoV-2 and the propensity of virus to infect the brain, we sought to determine if anti-infective biologics could protect against disease in this model system. We demonstrate that anti-SARS-CoV-2 human convalescent plasma protects K18-hACE2 against severe disease. All control mice succumbed to disease by day 7; however, all treated mice survived infection without observable signs of disease. In marked contrast to control mice, viral antigen and lesions were reduced or absent from lungs and absent in brains of antibody-treated mice. Our findings support the use of K18-hACE2 mice for protective efficacy studies of anti-SARS-CoV-2 medical countermeasures (MCMs). They also support the use of this system to study SARS-CoV-2 persistence and host recovery.

Printed 3-Dimensional Computed Tomography Scanned Ankle Fractures as an Educational Instrument.

The evaluation of and treatment protocols for ankle fractures represents an important aspect of the education of podiatric medical students. The objective of this investigation was to examine the feasibility of and student satisfaction with using 3-dimensional (3D) printed bone models representative of the Lauge-Hansen classification. The computed tomography scans of subjects with actual rotational ankle fractures representative of the Lauge-Hansen classification were identified and extracted into a format compatible with a 3D printer. The models were approximately 20 cm in height and made of acrylonitrile butadiene styrene plastic in ivory color. These were subsequently implemented into the curriculum of a traumatology course with third year podiatric medical students in the form of a hands-on workshop. Students expressed high levels of satisfaction with the use of these models, and most recommended their continued implementation within the curriculum. The results of this investigation indicate that 3D technology within podiatric medical education is feasible with high levels of student satisfaction.

A fixed moderate-dose combination of tiletamine+zolazepam outperforms midazolam in induction of short-term immobilization of ball pythons (Python regius).

Laboratory animals are commonly anesthetized to prevent pain and distress and to provide safe handling. Anesthesia procedures are well-developed for common laboratory mammals, but not as well established in reptiles. We assessed the performance of intramuscularly injected tiletamine (dissociative anesthetic) and zolazepam (benzodiazepine sedative) in fixed combination (2 mg/kg and 3 mg/kg) in comparison to 2 mg/kg of midazolam (benzodiazepine sedative) in ball pythons (Python regius). We measured heart and respiratory rates and quantified induction parameters (i.e., time to loss of righting reflex, time to loss of withdrawal reflex) and recovery parameters (i.e., time to regain righting reflex, withdrawal reflex, normal behavior). Mild decreases in heart and respiratory rates (median decrease of <10 beats per minute and <5 breaths per minute) were observed for most time points among all three anesthetic dose groups. No statistically significant difference between the median time to loss of righting reflex was observed among animals of any group (p = 0.783). However, the withdrawal reflex was lost in all snakes receiving 3mg/kg of tiletamine+zolazepam but not in all animals of the other two groups (p = 0.0004). In addition, the time for animals to regain the righting reflex and resume normal behavior was longer in the drug combination dose groups compared to the midazolam group (p = 0.0055). Our results indicate that midazolam is an adequate sedative for ball pythons but does not suffice to achieve reliable immobilization or anesthesia, whereas tiletamine+zolazepam achieves short-term anesthesia in a dose-dependent manner.

May-Thurner Syndrome in Operative Ankle Fracture Dislocations: A Case Report.

May-Thurner syndrome (MTS) is a rare condition in which patients develop iliofemoral deep venous thrombosis owing to an anatomic variant in which the right common iliac artery overlies and compresses the left common iliac vein against the lumbar spine. Data regarding lower extremity trauma in patients with previously diagnosed MTS are rare. We discuss the operative approach for ankle trauma occurring 3 weeks after endovascular surgery for the treatment of MTS.

Complete First Ray Polydactyly: A Case Report.

Polydactyly has been described as the most common congenital deformity in children. However, it is less common in the foot, with surgical treatment for the deformity less commonly described in reported studies. We present a rare case of polydactyly, with complete first ray duplication, in an infant female. The purpose of our report was to outline a surgical plan and to discuss our results when treating this rare presentation of polydactyly.

Topical ketamine cream in the treatment of painful diabetic neuropathy: a randomized, placebo-controlled, double-blind initial study.

BACKGROUND: Painful diabetic neuropathy remains a difficult pathologic condition to manage effectively despite numerous pharmacologic interventions. A randomized, placebo-controlled, double-blind study was undertaken to determine whether topical 5% ketamine cream is effective in reducing the pain of diabetic neuropathy. METHODS: Seventeen diabetic patients completed the study. The Michigan Neuropathy Screening Instrument was used to determine whether the neuropathy was likely caused by the diabetic condition. Hemoglobin A(1c) levels were measured before treatment. Patients applied 1 mL of either ketamine cream or placebo cream for 1 month. The intensity of seven different pain characteristics was evaluated before and after treatment. A two-way repeated analysis of variance design was used to test for differences between treatments and within patients (time). RESULTS: We found no significant treatment main effect, but pain improved significantly over time in both groups. There was no statistical interaction effect (treatment × time) in any of the pain characteristics, indicating that pain improved in the two treatment groups similarly with time. CONCLUSIONS: The 5% topical ketamine cream was no more effective than was placebo in relieving pain caused by diabetic neuropathy.

Radiofrequency thermoneurolysis for the treatment of Morton's neuroma.

Pedal neuroma is a common disorder. The authors undertook a review of 32 feet in 29 patients with a symptomatic neuroma treated between January 2007 and January 2010 to evaluate the effectiveness of radiofrequency thermoneurolysis therapy in alleviating symptoms. Overall relief of symptoms was rated as complete by 24 (83%) patients, with 5 patients experiencing minimal to no relief. Two patients were lost to follow-up after 1 month, 2 patients opted for no further intervention, and 1 patient went to open resection of the neuroma. Average follow-up was 13 months and total recovery time was 2 days. Complications included 1 foot with cellulitis treated by a course of oral antibiotics. The results of this retrospective study indicate radiofrequency thermoneurolysis therapy is a safe, effective, and minimally invasive alternative treatment for symptomatic neuromas of the foot.