Pain hypersensitivity, sensorimotor impairment, and decreased muscle force in a novel rat model of radiation-induced peripheral neuropathy.

INTRODUCTION: Radiation-induced peripheral neuropathy is a rare, but serious complication often resulting in profound morbidity, life-long disability, and chronic debilitating pain. Unfortunately, this type of peripheral neuropathy is usually progressive, and almost always irreversible. To date, a standardized rat model of radiation-induced peripheral neuropathy has not been established. The purpose of the present study was to examine neuropathic pain, sensorimotor impairment, and muscle force parameters following the administration of a clinically relevant radiation dose in a rat model. METHODS: Ten rats were randomly assigned to one of two experimental groups: (1) radiation and (2) sham-radiated controls. Radiated animals were given a clinically relevant dose of 35 Gray (Gy) divided into five daily doses of 7 Gy/day. This regimen represents a human equivalent dose of 70 Gy, approximating the same dosage utilized for radiotherapy in oncologic patients. Sham-radiated controls were anesthetized and placed in the radiation apparatus but were not given radiation. All animals were tested for baseline values in both sensorimotor and pain behavioral tests. Sensorimotor testing consisted of the evaluation of walking tracks with the calculation of the Sciatic Functional Index (SFI). Pain-related behavioral measures consisted of mechanical allodynia (von Frey test), cold allodynia (Acetone test), and thermal allodynia (Hargreaves test). Animals were tested serially over an 8-week period. At the study endpoint, electrophysiological and muscle force assessments were completed, and histomorphometric analysis was performed on all sciatic nerves. RESULTS: Animals that underwent radiation treatment displayed significantly greater pain hypersensitivity to mechanical stimulation as compared to sham radiated controls from weeks 4 to 8 of testing. SFI values indicated sensorimotor impairments in the overground gait of radiated animals as compared to non-radiated animals. Furthermore, radiated animals displayed reduced twitch and tetanic muscle force when compared to sham radiated controls. CONCLUSIONS: A clinically relevant human equivalent dose of fractionated 35 Gy in rats established significant pain hypersensitivity, impairments in sensorimotor locomotion, and decreased muscle force capacity. This novel rodent model of radiation-induced peripheral neuropathy can be utilized to assess the potential efficacy of therapeutic treatments to either prevent or remediate this clinically debilitating condition.

Optimizing immunofluorescent staining of H vessels within an irradiated fracture callus in paraffin-embedded tissue samples.

H vessels are an essential link in angiogenic-osteogenic coupling and orchestrate the process of bone healing. H vessels are critically deficient in the setting of radiation-induced fractures, which have been reported to occur in up to 25% of patients undergoing radiotherapy. By increasing H-vessel proliferation, Deferoxamine (DFO) revitalizes the physiologic response to skeletal injury and accelerates irradiated fracture repair. H-vessel quantification is therefore an important outcome measure in histologic analysis of bone healing. However, an optimized protocol for staining H vessels in formalin-fixed paraffin-embedded (FFPE) tissue sections has not been reported. With this protocol, we describe a method of staining FFPE bone samples with minimal background fluorescence and high signal-to-noise ratio. We examined mandibular specimens in a rat model of bone healing from a range of fracture conditions, including healthy bone (Fx), irradiated bone (XFx), and irradiated bone with DFO treatment (XFx-DFO). Quantitative analysis revealed a significant increase of H vessels in the XFxDFO group compared to both the Fx and XFx groups. By optimizing immunofluorescent staining of H vessels in FFPE samples across a range of fracture conditions, we offer investigators an efficacious means of producing reliable imaging for quantitative analysis of H vessels in an irradiated fracture callus.

"Longitudinal Experience Using Pedicled Buccal Fat Pad Flaps in Cleft Palatoplasty: Mitigating Velopharyngeal Insufficiency Risk and Severity".

BACKGROUND: Cleft palatoplasty commonly results in denuded maxillary bone in the lateral gutter(s) and a posterior void between oral and nasal closures. Bony exposure of the anterior palate subjects the maxilla to scarring and growth restriction, while scar contracture of the posterior void may result in velopharyngeal insufficiency (VPI) and fistula formation. Utilization of the buccal fat pad flap (BFPF) at the time of palatoplasty provides vascularized tissue over these critical areas, thereby reducing the rate of secondary surgery for speech and fistula revision. METHODS: A single-center, retrospective review identified patients who underwent palatoplasty with or without BFPF between 1995-2015. Data collected included cleft type, surgical technique, follow-up duration, and complications. Outcomes included rate of speech surgery and palatal fistula development. Veau phenotype index was computed on a scale of 2-4 as a weighted mean to reflect the frequency of cleft type (Veau II-IV) in BFPF and non-BFPF groups. RESULTS: Charts of 866 patients were reviewed; 212 met inclusion criteria. Of these, 101 received a BFPF. Mean follow-up duration was 11.4 years. Despite a selection bias for more severe clefts, the BFPF group had lower incidence of speech surgery (9.9% vs. 36.9%, p=0.0072). The BFPF group had more mild cases treatable with fat injection (7.9% vs. 2.7%, p=0.0346) and developed fewer fistulas (6.9% vs. 18.0%, p=0.0280). CONCLUSION: Despite the presence of more severe clefts, the BFPF group had a significantly lower rate of speech surgery. The BFPF is a valuable adjunct in primary palatoplasty, reducing VPI and fistula formation.

H Vessel Formation as a Marker for Enhanced Bone Healing in Irradiated Distraction Osteogenesis.

In the setting of bone defects, the injured vasculature and loss of hemodynamic inflow leads to hematoma formation and low oxygen tension which stimulates vascular expansion through the HIf-1α pathway. Most importantly, this pathway upregulates sprouting of type H vessels (CD31hiEmcnhi vessels). H vessels engage in direct interaction with perivascular osteoprogenitor cells (OPCs), osteoblasts, and preosteoclasts of bone formation and remodeling. This angiogenic-osteogenic coupling leads to synchronous propagation of vascular and bony tissue for regenerative healing. A growing body of literature demonstrates that H vessels constitute a large portion of bone's innate capacity for osteogenic healing. We believe that CD31hiEmcnhi vessels play a role in bone healing during distraction osteogenesis (DO). DO is a procedure that utilizes traction forces to facilitate induction of endogenous bone formation and regeneration of surrounding soft tissues such as skin, muscle, tendon, and neurovascular structures. While the H vessel response to mechanical injury is adequate to facilitate healing in normal healthy tissue, it remains inadequate to overcome the devastation of radiation. We posit that the destruction of CD31hiEmcnhi vessels plays a role in precluding DO's effectiveness in irradiated bone defect healing. We aim, therefore, to recapitulate the normal pathway of bony healing by utilizing the regenerative capacity of H vessels. We hypothesize that using localized application of deferoxamine (DFO) will enhance the H vessel-mediated vasculogenic response to radiation damage and ultimately enable osteogenic healing during DO. This discovery could potentially be exploited by developing translational therapeutics to hopefully accelerate bone formation and shorten the DO consolidation period, thereby potentially expanding DO's utilization in irradiated bone healing. Sprague-Dawley rats were divided into three groups: DO, radiation with DO (xDO), and radiation with DO and DFO implantation (xDODFO). Experimental groups received 35 Gy of radiation. All groups underwent DO. The treatment group received injections into the osteotomy site, every other day, beginning on postoperative day (POD) 4 of DFO. Animals were sacrificed on POD 40. For immunohistochemical analysis, mandibles were dissected and fixed in 4% paraformaldehyde for 48 hours, decalcified in Cal-Ex II for 2 days, dehydrated through graded ethanol of increasing concentration, and then embedded in paraffin. Samples were cut into 7-µm thick longitudinally oriented sections including the metaphysis and diaphysis. CD31 and Emcn double immunofluorescent staining were performed to evaluate the extent of CD31hiEmcnhi vessel formation. Bone sections were then stained with conjugated antibodies overnight at 4°C. Nuclei were stained with Hoechst. Slides were also double stained with Osterix and CD31 to study the quantity of H vessel-mediated recruitment of OPCs to accelerate bone healing. Images were acquired with a Nikon Ti2 widefield microscope and analyzed in NIS- Elements Advanced Research 5.41.02 software. The abundance of type H vessels is represented by the area fraction of CD31 + Emcn+ vessel area inside the regenerate sample. OPC concomitant proliferation into the distraction gap is represented by the area fraction of Osterix+ cell area inside of the regenerate sample. There were 6× more type H vessels in DO groups than in xDO groups. Localized DFO significantly increased the abundance of type H vessels of irradiated DO animals compared to xDO by 15× ( p = 0.00133531). Moreover, the DO and xDODFO groups with higher abundance of type H vessels also demonstrated better angiogenesis and osteogenesis outcomes. Interestingly, xDODFO groups doubled the quantity of H vessel formation compared to DO, indicating a supraphysiologic response ( p = 0.044655055). Furthermore, H vessel-mediated recruitment of OPCs mimicked the described H vessel formation trend in our study groups. Irradiated DO groups contained 3× less OPCs compared to DO controls. DFO treatment to xDO animals remediated irradiation damage by containing 12× Osterix+ cells. Finally, DFO treatment of irradiated animals quadrupled osteoprogenitor recruitment into the distraction gap compared to DO controls. In this study, we developed a novel approach to visualize CD31hiEmcnhi in paraffin sections to study DO regeneration. Normal DO demonstrated a significant upregulation of H vessel formation and associated angiogenic-osteogenic coupling. Radiation severely decreased H vessel formation along with an associated significant diminution of new bone formation and nonunion. DFO administration, however, resulted in vascular replenishment and the restoration of high quantities of CD31hiEmcnhi and OPCs, recapitulating the normal process of bony regeneration and repair. DFO treatment remediated new bone formation and bony union in irradiated fields associated with increased H vessel angiogenic-osteogenic coupling. While further studies are required to optimize this approach, the results of this study are incredibly promising for the long-awaited translation of localized DFO into the clinical arena.

Reasons for Removal of Rigid Internal Fixation Devices in Craniofacial Surgery: A 20-year Update.

The hardware utilized for rigid internal fixation of the craniofacial skeleton has evolved over time. Thus, the reasons for the unplanned removal of hardware continue to change. The purpose of this study is to compare past (1989-1995) and present (2000-2020) patient cohorts to establish trends related to unplanned removal of craniofacial hardware. A retrospective review study was designed. Data from our institution's original publication describing the unplanned removal of craniofacial hardware (1989-1995) was obtained. Data related to patients who underwent unplanned removal of hardware from 2000 to 2020 was collected from the electronic medical record. A descriptive statistical analysis was performed to compare demographics, reasons for hardware placement, and reasons for unplanned hardware removal between cohorts. This study includes 55 patients treated from 1989 to 1995 and 184 patients treated from 2000 to 2020. The average age at hardware placement decreased from 32 years (1989-1995) to 28 years (2000-2020). The most common reason for hardware placement changed from motor vehicle accident (1989-1995) to congenital deformity (2000-2020). The length of time with hardware in situ increased from 13 months (1989-1995) to 25 months (2000-2020). The most common reason for hardware removal changed from prominent hardware (1989-1995) to hardware exposure (2000-2020). In summary, patients who underwent rigid internal fixation of the craniofacial skeleton from 2000 to 2020 retained their hardware 2 times longer than patients treated from 1989 to 1995. Factors potentially contributing to increased retention include improved surgical technique, decreased profile of hardware, and increased surgeon experience. Further studies are warranted to define preoperative risk factors for unplanned hardware removal.

Adipose-Derived Stem Cells Enhance Graft Incorporation and Mineralization in a Murine Model of Irradiated Mandibular Nonvascularized Bone Grafting.

BACKGROUND: Nonvascularized bone grafting represents a practical method of mandibular reconstruction. However, the destructive effects of radiotherapy on native bone preclude the use of nonvascularized bone grafts in head and neck cancer patients. Adipose-derived stem cells have been shown to enhance bone healing and regeneration in numerous experimental models. The purpose of this study was to determine the impact of adipose-derived stem cells on nonvascularized bone graft incorporation in a murine model of irradiated mandibular reconstruction. METHODS: Thirty isogenic rats were randomly divided into 3 groups: nonvascularized bone graft (control), radiation with nonvascularized bone graft (XRT), and radiation with nonvascularized bone graft and adipose-derived stem cells (ASC). Excluding the control group, all rats received a human-equivalent dose of radiation. All groups underwent mandibular reconstruction of a critical-sized defect with a nonvascularized bone graft from the contralateral hemimandible. After a 60-day recovery period, graft incorporation and bone mineralization were compared between groups. RESULTS: Compared with the control group, the XRT group demonstrated significantly decreased graft incorporation (P = 0.011), bone mineral density (P = 0.005), and bone volume fraction (P = 0.001). Compared with the XRT group, the ASC group achieved a significantly increased graft incorporation (P = 0.006), bone mineral density (P = 0.005), and bone volume fraction (P = 0.013). No significant differences were identified between the control and ASC groups. CONCLUSIONS: Adipose-derived stem cells enhance nonvascularized bone graft incorporation in the setting of human-equivalent radiation.

Overcoming Nuclear Winter: The Cutting-edge Science of Bone Healing and Regeneration in Irradiated Fields.

BACKGROUND: The incidence of cancer worldwide is expected to be more than 22 million annually by 2030. Approximately half of these patients will likely require radiation therapy. Although radiotherapy has been shown to improve disease control and increase survivorship, it also results in damage to adjacent healthy tissues, including the bone, which can lead to devastating skeletal complications, such as nonunion, pathologic fractures, and osteoradionecrosis. Pathologic fractures and osteoradionecrosis are ominous complications that can result in large bone and soft tissue defects requiring complex reconstruction. Current clinical management strategies for these conditions are suboptimal and dubious at best. The gold standard in treatment of severe radiation injury is free tissue transfer; however, this requires a large operation that is limited to select candidates. METHODS: With the goal to expand current treatment options and to assuage the devastating sequelae of radiation injury on surrounding normal tissue, our laboratory has performed years of translational studies aimed at remediating bone healing and regeneration in irradiated fields. Three therapeutics (amifostine, deferoxamine, and adipose-derived stem cells) have demonstrated great promise in promoting healing and regeneration of irradiated bone. RESULTS: Amifostine confers prophylactic protection, whereas deferoxamine and adipose-derived stem cells function to remediate postradiation associated injury. CONCLUSIONS: These prospective therapeutics exploit a mechanism attributed to increasing angiogenesis and ultimately function to protect or restore cellularity, normal cellular function, osteogenesis, and bone healing to nonirradiated metrics. These discoveries may offer innovative treatment alternatives to free tissue transfer with the added benefit of potentially preventing and treating osteoradionecrosis and pathologic fractures.

Upper Extremity Arterial Thromboembolism in a Coronavirus Patient. A Case Report.

The coronavirus disease 2019 pandemic has impacted millions of people worldwide. This novel virus has a variety of presentations and complications. Notably, patients with this infection have an associated coagulopathy, presenting with symptoms such as gastrointestinal bleeds, deep vein thrombosis, ischemic cerebrovascular events, and pulmonary embolism. Although there are documented cases of venous thromboembolism in patients with coronavirus disease 2019, the authors present an interesting case of upper extremity arterial thromboembolism in a 75-year-old patient surgically treated for arterial thrombus removal. We also discuss diagnosis, medical management, and surgical approach to an upper extremity arterial thromboembolism in a patient with coronavirus disease 2019, to highlight the challenges of hypercoagulability in such patients.

Surgery for Stress Urinary Incontinence: Autologous Fascial Sling.

This article describes the operative technique of autologous fascial pubovaginal sling (AFPVS) surgery, examines the senior author's outcomes with AFPVS, compares these outcomes with those of other large studies and meta-analyses, and compares the safety and efficacy of AFPVS with those of the synthetic midurethral sling (SMUS). Recently, the SMUS has become the treatment of choice for most surgeons. The efficacy of the SMUS remains unchallenged and comparable with that of AFPVS, but SMUS are associated with more severe complications. In the author's opinion, the AFPVS should remain the gold standard for treating SUI.

Tinea capitis caused by dermatophytes: a 15-year retrospective study from a Mississippi Dermatology Clinic.

Tinea capitis is a highly contagious disorder occurring predominantly in children. Presentation is variable and, as such, mycologic confirmation of dermatophyte infection would be useful in targeting specific therapy and implementing preventive measures to interrupt spread of infection. This retrospective study was performed at an outpatient dermatology clinic in Jackson, Mississippi, over a 15-year period (1983-1998). Dermatophyte infections were confirmed using scalp scrapings cultured on Mycosel Agar containing cycloheximide and chloramphenicol. Cultures were performed on 1220 patients of all ages presenting with signs and symptoms suggestive of tinea capitis. Of the total patients meeting the inclusion criteria, 66% were younger than 13 years. Overall, 39% (478/1220) had positive cultures for dermatophytes, with black individuals having the highest percentage of positive cultures (87% [414/478]). In addition to a review of findings, we examine the impact of a cultural diagnosis of dermatophyte infection on the treatment and prevention of this highly contagious infection.

Managing simple chronic paronychia and onycholysis with ciclopirox 0.77% and an irritant-avoidance regimen.

Dermatologists and other physicians frequently encounter simple chronic paronychia and onycholysis. In addition to strict avoidance of contact irritants, a broad-spectrum topical antifungal agent has been recommended. We conducted an examination of treatment with this type of agent and an assessment of the efficacy of ciclopirox 0.77% topical suspension in combination with a strict irritant-avoidance regimen. Early results of a pilot study (N = 44) using ciclopirox 0.77% topical suspension in patients diagnosed with simple chronic paronychia and/or onycholysis show excellent therapeutic outcomes of a combined regimen of a broad-spectrum topical antifungal agent such as ciclopirox and contact-irritant avoidance in this patient population.