Osteoradionecrosis of the Cervical Spine: An Analysis of the Literature

OBJECTIVES

The purpose of this manuscript is to review the current literature on osteoradionecrosis of the cervical spine (C-ORN) and to summarize the risk factors, presenting symptoms and management strategies of this rare condition.

STUDY DESIGN

A systematic review of the literature on C-ORN was completed using PubMed. Nineteen articles met criteria; 97 patient cases were identified. Statistical analysis was completed from the patient cases.

RESULTS

Of the analyzed patients, 72% are male and 28% are female with an average age of 57.7 years. Nasopharyngeal carcinoma was the most common initial diagnosis (72%). Thyroid and other lower neck cancers were associated with a later onset of C-ORN compared with other cancers. C-ORN more commonly occurred in the clivus to C2 (55.3%, P = .004). Onset of C-ORN significantly differed for men (n = 6.99 years) and women (n = 17.5 years) (P = .022).

CONCLUSION

C-ORN can be a devastating complication of head and neck radiation therapy. C-ORN is associated with nasopharyngeal carcinoma, and most commonly affects the area of the clivus to cervical vertebrae C2. Cancers of the lower neck and female sex are associated with later onset. Initial presentation ranges from asymptomatic to severe neurologic deficits; the degree of intervention should be congruent with the severity of presenting symptoms. As long-term survival of patients with head and neck cancer increase, this complication may become more prevalent.

A nanoengineered topical transmucosal cisplatin delivery system induces anti-tumor response in animal models and patients with oral cancer

Despite therapeutic advancements, oral cavity squamous cell carcinoma (OCSCC) remains a difficult disease to treat. Systemic platinum-based chemotherapy often leads to dose-limiting toxicity (DLT), affecting quality of life. PRV111 is a nanotechnology-based system for local delivery of cisplatin loaded chitosan particles, that penetrate tumor tissue and lymphatic channels while avoiding systemic circulation and toxicity. Here we evaluate PRV111 using animal models of oral cancer, followed by a clinical trial in patients with OCSCC. In vivo, PRV111 results in elevated cisplatin retention in tumors and negligible systemic levels, compared to the intravenous, intraperitoneal or intratumoral delivery. Furthermore, PRV111 produces robust anti-tumor responses in subcutaneous and orthotopic cancer models and results in complete regression of carcinogen-induced premalignant lesions. In a phase 1/2, open-label, single-arm trial (NCT03502148), primary endpoints of efficacy (≥30% tumor volume reduction) and safety (incidence of DLTs) of neoadjuvant PRV111 were reached, with 69% tumor reduction in ~7 days and over 87% response rate. Secondary endpoints (cisplatin biodistribution, loco-regional control, and technical success) were achieved. No DLTs or drug-related serious adverse events were reported. No locoregional recurrences were evident in 6 months. Integration of PRV111 with current standard of care may improve health outcomes and survival of patients with OCSCC.

A phase II study of PRV111 nanoengineered cisplatin patch as a neoadjuvant therapy for early-stage oral squamous cell carcinoma (OSCC)

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Background: OSCC is a devastating disease causing substantial morbidity and mortality. Despite advancements in the conventional therapeutic approaches, surgical resection often leads to permanent disfigurement, while radiotherapies and systemic platinum-based chemotherapy result in significant toxicities, affecting patient wellbeing and quality of life. Thus, development of novel therapeutic approaches is paramount to improve health outcomes and survival of patients with OSCC. Systemic toxicity is often dose limiting, but could be tentatively reduced by locoregional administration. We have developed PRV111, a nanotechnology based patch for local and regional delivery of highly concentrated potent cisplatin, designed to penetrate tumor tissue, reach and enter regional lymph nodes and avoid systemic circulation. Here we present the results of phase 1/2 CLN-001 trial, designed to improve efficacy and reduce toxicity by neoadjuvant treatment with PRV111. Methods: A phase 1/2, single arm, open-label CLN-001 (NCT03502148) study has enrolled 12 patients with confirmed OSCC; unknown nodal involvement, no distant metastasis, and tumor size ≤ 4.0 cm. Three weeks prior to surgery, patients were administered 1 cycle of standalone neoadjuvant PRV111, consisting of up to 4 treatment visits (each visit dose: ≤12mg of cisplatin, each patch loading dose: 2mg of cisplatin). The primary endpoints were safety, efficacy and tumor reduction in ̃ 7 days by greater than 30%. Secondary endpoints included nanoengineered patch consistent and complete adhesion to mucosal surfaces and uniform drug release. Exploratory endpoints included immunogenesis/immunomodulation. Results: PRV111 successfully met all clinical primary endpoints, as well as safety and efficacy objectives. It caused over 70% tumor reduction in ̃7 days with over 87% response rate across 10 subjects. No dose-limiting toxicities, serious adverse event, or systemic toxicities were reported and no locoregional recurrences were evident in 6 months. PRV111 induced ̃15 times increase in tumor infiltrating lymphocytes compared with the initial biopsy. Concentrations of cisplatin found in the tumor and regional lymph nodes were over 300 and 100 times higher respectively as compared with IV cisplatin, with only negligible amount of cisplatin found in the blood. Grade 1 or 2 oral and tongue pain induced by the treatment were the most common adverse events. Furthermore, 97.5% successful patch performance was achieved across 182 patches used in the study. Conclusions: Adding neoadjuvent PRV111 to the care for patients with OSCC may improve the surgical outcome and increase event free survival. Given these encouraging results, future studies are needed to establish the application of this non-invasive platform in head and neck SCC and other epithelial cancers, including anal, colorectal, genitourinary, nasal, and skin. Clinical trial information: NCT03502148.

Localized mandibular infection affects remote in vivo bioreactor bone generation

Mandibular reconstruction requires functional and aesthetic repair and is further complicated by contamination from oral and skin flora. Antibiotic-releasing porous space maintainers have been developed for the local release of vancomycin and to promote soft tissue attachment. In this study, mandibular defects in six sheep were inoculated with 106 colony forming units of Staphylococcus aureus; three sheep were implanted with unloaded porous space maintainers and three sheep were implanted with vancomycin-loaded space maintainers within the defect site. During the same surgery, 3D-printed in vivo bioreactors containing autograft or xenograft were implanted adjacent to rib periosteum. After 9 weeks, animals were euthanized, and tissues were analyzed. Antibiotic-loaded space maintainers were able to prevent dehiscence of soft tissue overlying the space maintainer, reduce local inflammatory cells, eliminate the persistence of pathogens, and prevent the increase in mandibular size compared to unloaded space maintainers in this sheep model. Animals with an untreated mandibular infection formed bony tissues with greater density and maturity within the distal bioreactors. Additionally, tissues grown in autograft-filled bioreactors had higher compressive moduli and higher maximum screw pull-out forces than xenograft-filled bioreactors. In summary, we demonstrated that antibiotic-releasing space maintainers are an innovative approach to preserve a robust soft tissue pocket while clearing infection, and that local infections can increase local and remote bone growth.

Biomaterials-aided mandibular reconstruction using in vivo bioreactors

Large mandibular defects are clinically challenging to reconstruct due to the complex anatomy of the jaw and the limited availability of appropriate tissue for repair. We envision leveraging current advances in fabrication and biomaterials to create implantable devices that generate bone within the patients themselves suitable for their own specific anatomical pathology. The in vivo bioreactor strategy facilitates the generation of large autologous vascularized bony tissue of customized geometry without the addition of exogenous growth factors or cells. To translate this technology, we investigated its success in reconstructing a mandibular defect of physiologically relevant size in sheep. We fabricated and implanted 3D-printed in vivo bioreactors against rib periosteum and utilized biomaterial-based space maintenance to preserve the native anatomical mandibular structure in the defect site before reconstruction. Nine weeks after bioreactor implantation, the ovine mandibles were repaired with the autologous bony tissue generated from the in vivo bioreactors. We evaluated tissues generated in bioreactors by radiographic, histological, mechanical, and biomolecular assays and repaired mandibles by radiographic and histological assays. Biomaterial-aided mandibular reconstruction was successful in a large superior marginal defect in five of six (83%) sheep. Given that these studies utilized clinically available biomaterials, such as bone cement and ceramic particles, this strategy is designed for rapid human translation to improve outcomes in patients with large mandibular defects.

Reconstruction of large mandibular defects using autologous tissues generated from in vivo bioreactors

Reconstruction of large mandibular defects is clinically challenging due to the need for donor tissue of appropriate shape and volume to facilitate high fidelity repair. In order to generate large vascularized tissues of custom geometry, bioreactors were implanted against the rib periosteum of 3-4year-old sheep for nine weeks. Bioreactors were filled with either morcellized autologous bone, synthetic ceramic particles, or a combination thereof. Tissues generated within synthetic graft-filled bioreactors were transferred into a large right-sided mandibular angle defect as either avascular grafts (n=3) or vascularized free flaps (n=3). After twelve additional weeks, reconstructed mandibular angles were harvested and compared to contralateral control angles. Per histologic and radiologic evaluation, a greater amount of mineralized tissue was generated in bioreactors filled with autologous graft although the quality of viable bone was not significantly different between groups. Genetic analyses of soft tissue surrounding bioreactor-generated tissues demonstrated similar early and late stage osteogenic biomarker expression (Runx2 and Osteocalcin) between the bioreactors and rib periosteum. Although no significant differences between the height of reconstructed and control mandibular angles were observed, the reconstructed mandibles had decreased bone volume. There were no differences between mandibles reconstructed with bioreactor-generated tissues transferred as flaps or grafts. Tissues used for mandibular reconstruction demonstrated integration with native bone as well as evidence of remodeling. In this study, we have demonstrated that synthetic scaffolds are sufficient to generate large volumes of mineralized tissue in an in vivo bioreactor for mandibular reconstruction.

STATEMENT OF SIGNIFICANCE

A significant clinical challenge in craniofacial surgery is the reconstruction of large mandibular defects. In this work, we demonstrated that vascularized tissues of large volume and custom geometry can be generated from in vivo bioreactors implanted against the rib periosteum in an ovine model. The effects of different bioreactor scaffold material on tissue ingrowth were measured. To minimize donor site morbidity, tissues generated from bioreactors filled with synthetic graft were transferred as either vascularized free flaps or avascular grafts to a large mandibular defect. It was demonstrated that synthetic graft in an in vivo bioreactor is sufficient to produce free tissue bone flaps capable of integrating with native tissues when transferred to a large mandibular defect in an ovine model.

Bone Tissue Engineering Challenges in Oral & Maxillofacial Surgery

Over the past decades, there has been a substantial amount of innovation and research into tissue engineering and regenerative approaches for the craniofacial region. This highly complex area presents many unique challenges for tissue engineers. Recent research indicates that various forms of implantable biodegradable scaffolds may play a beneficial role in the clinical treatment of craniofacial pathological conditions. Additionally, the direct delivery of bioactive molecules may further increase de novo bone formation. While these strategies offer an exciting glimpse into potential future treatments, there are several challenges that still must be overcome. In this chapter, we will highlight both current surgical approaches for craniofacial reconstruction and recent advances within the field of bone tissue engineering. The clinical challenges and limitations of these strategies will help contextualize and inform future craniofacial tissue engineering strategies.

Heat activatable 3'-modified dNTPs: synthesis and application for hot start PCR

Several 3'-ether and 3'-ester derivatives of 2'-deoxyribonucleoside 5'-triphosphates (dNTPs) were prepared. These dNTP derivatives were not substrates for DNA polymerase and did not support primer extension at room temperature. However, by short pre-heating to 95 degrees C in PCR buffer, these 3'-modified dNTPs can be converted to corresponding unmodified natural dNTPs that efficiently support PCR amplification. The analysis of PCR products obtained with 3'-modified dNTPs revealed a significant improvement in PCR performance resulting in higher amplicon yield and reduced formation of off-target products (mis-priming and primer dimer). Among the studied 3'-modified dNTPs, the 3'-tetrahydrofuranyl derivatives showed the best results.

Hot start PCR

Hot Start activation approaches are increasingly being used to improve the performance of PCR. Since the inception of Hot Start as a means of blocking DNA polymerase extension at lower temperatures, a number of approaches have been developed that target the essential reaction components such as magnesium ion, DNA polymerase, oligonucleotide primers, and dNTPs. Herein, five different Hot Start activation protocols are presented. The first method presents the use of barriers as a means of segregating key reaction components until a Hot Start activation step. The second and third protocols demonstrate Hot Start approaches to block DNA polymerase activity through the use of anti-DNA polymerase antibodies and accessory proteins, respectively. The fourth and fifth protocols utilize thermolabile chemical modifications to the oligonucleotide primers and dNTPs. The results presented demonstrate that all protocols significantly improve the specificity of traditional thermal cycling protocols.

Chemically modified primers for improved multiplex polymerase chain reaction

Multiplex polymerase chain reaction (PCR), the amplification of multiple targets in a single reaction, presents a new set of challenges that further complicate more traditional PCR setups. These complications include a greater probability for nonspecific amplicon formation and for imbalanced amplification of different targets, each of which can compromise quantification and detection of multiple targets. Despite these difficulties, multiplex PCR is frequently used in applications such as pathogen detection, RNA quantification, mutation analysis, and (recently) next generation DNA sequencing. Here we investigated the utility of primers with one or two thermolabile 4-oxo-1-pentyl phosphotriester modifications in improving multiplex PCR performance. Initial endpoint and real-time analyses revealed a decrease in off-target amplification and a subsequent increase in amplicon yield. Furthermore, the use of modified primers in multiplex setups revealed a greater limit of detection and more uniform amplification of each target as compared with unmodified primers. Overall, the thermolabile modified primers present a novel and exciting avenue for improving multiplex PCR performance.

Hot start PCR with heat-activatable primers: a novel approach for improved PCR performance

The polymerase chain reaction (PCR) is widely used for applications which require a high level of specificity and reliability, such as genetic testing, clinical diagnostics, blood screening, forensics and biodefense. Great improvements to PCR performance have been achieved by the use of Hot Start activation strategies that aim to prevent DNA polymerase extension until more stringent, higher temperatures are reached. Herein we present a novel Hot Start activation approach in PCR where primers contain one or two thermolabile, 4-oxo-1-pentyl (OXP) phosphotriester (PTE) modification groups at 3′-terminal and 3′-penultimate internucleotide linkages. Studies demonstrated that the presence of one or more OXP PTE modifications impaired DNA polymerase primer extension at the lower temperatures that exist prior to PCR amplification. Furthermore, incubation of the OXP-modified primers at elevated temperatures was found to produce the corresponding unmodified phosphodiester (PDE) primer, which was then a suitable DNA polymerase substrate. The OXP-modified primers were tested in conventional PCR with endpoint detection, in one-step reverse transcription (RT)–PCR and in real-time PCR with SYBR Green I dye and Taqman® probe detection. When OXP-modified primers were used as substitutes for unmodified PDE primers in PCR, significant improvement was observed in the specificity and efficiency of nucleic acid target amplification.

Dual localization pathways for the engulfment proteins during Bacillus subtilis sporulation

Engulfment in Bacillus subtilis is mediated by two complementary systems, SpoIID, SpoIIM and SpoIIP (DMP), which are essential for engulfment, and the SpoIIQ-SpoIIIAGH (Q-AH) zipper, which provides a secondary engulfment mechanism and recruits other proteins to the septum. We here identify two mechanisms by which DMP localizes to the septum. The first depends on SpoIIB, which is recruited to the septum during division and provides a septal landmark for efficient DMP localization. However, sporangia lacking SpoIIB ultimately localize DMP and complete engulfment, suggesting a second mechanism for DMP localization. This secondary targeting pathway depends on SpoIVFA and SpoIVFB, which are recruited to the septum by the Q-AH zipper. The absence of a detectable localization phenotype in mutants lacking only SpoIVFAB (or Q-AH) suggests that SpoIIB provides the primary DMP localization pathway while SpoIVFAB provides a secondary pathway. In keeping with this hypothesis, the spoIIB spoIVFAB mutant strain has a synergistic engulfment defect at septal thinning (which requires DMP) and is completely defective in DMP localization. Thus, the Q-AH zipper both provides a compensatory mechanism for engulfment when DMP activity is reduced, and indirectly provides a compensatory mechanism for septal localization of DMP when its primary targeting pathway is disrupted.

Évaluation des lames de laryngoscopes à usage unique

OBJECTIVES

To assess the feasibility of switching disposable laryngoscope blades and to compare the disposable blades available on the market to reusable blades within the context of a new variant of Creutzfeldt-Jakob disease.

STUDY DESIGN

Comparative prospective study.

MATERIAL AND METHODS

Study conducted on patients intubated for surgical procedures in all operating theatres of a university hospital. The anaesthetic practitioner filled in an assessment form giving a score on nine criteria for each blade used. Data were recorded on Epi Info software. Satisfaction scores of each criterion were compared for both disposable blades and reusable blades.

RESULTS

Six brands of blades were tested with 225 blades. Disposable blades were evaluated as inferior to the reusable blades in 62% of cases. Two blades were reported as more satisfactory: the 670166 Rusch-Pilling and Vital View blades.

CONCLUSION

The disposable blades were not easily accepted by the anaesthetists particularly for difficult intubations, which is why reusable blades should not be totally removed from practice. Single-use blades proposed by different manufacturers are not identical. We chose 670166 Rusch-Pilling blades, the best adapted to our institution. The switch to disposable blades would require that blade manufacturers improve the quality of the blades.