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BackgroundPrevious studies have shown that 5-HT3-antagonists reduce muscle pain, but there are no studies that have investigated the expression of 5-HT3-receptors in human muscles. Also, tetrodotoxin resistant voltage gated sodium-channels (NaV) are involved in peripheral sensitization and found in trigeminal ganglion neurons innervating the rat masseter muscle. This study aimed to investigate the frequency of nerve fibers that express 5-HT3A-receptors alone and in combination with NaV1.8 sodium-channels in human muscles and to compare it between healthy pain-free men and women, the pain-free masseter and tibialis anterior muscles, and patients with myofascial temporomandibular disorders (TMD) and pain-free controls.MethodsThree microbiopsies were obtained from the most bulky part of the tibialis and masseter muscles of seven and six healthy men and seven and six age-matched healthy women, respectively, while traditional open biopsies were obtained from the most painful spot of the masseter of five female patients and from a similar region of the masseter muscle of five healthy, age-matched women. The biopsies were processed by routine immunohistochemical methods. The biopsy sections were incubated with monoclonal antibodies against the specific axonal marker PGP 9.5, and polyclonal antibodies against the 5-HT3A-receptors and NaV1.8 sodium-channels.ResultsA similar percentage of nerve fibers in the healthy masseter (85.2%) and tibialis (88.7%) muscles expressed 5-HT3A-receptors. The expression of NaV1.8 by 5-HT3A positive nerve fibers associated with connective tissue was significantly higher than nerve fibers associated with myocytes (P < .001). In the patients, significantly more fibers per section were found with an average of 3.8 ± 3 fibers per section in the masseter muscle compared to 2.7 ± 0.2 in the healthy controls (P = .024). Further, the frequency of nerve fibers that co-expressed NaV1.8 and 5-HT3A receptors was significantly higher in patients (42.6%) compared to healthy controls (12.0%) (P < .001).ConclusionsThis study showed that the 5-HT3A-receptor is highly expressed in human masseter and tibialis muscles and that there are more nerve fibers that express 5-HT3A-receptors in the masseter of women with myofascial TMD compared to healthy women. These findings indicate that 5-HT3-receptors might be up-regulated in myofascial TMD and could serve as potential biomarkers of chronic muscle pain.

Background Patients with locally advanced, recurrent or metastatic solitary fibrous tumour are often treated with bevacizumab and temozolomide based on the clinical efficacy reported in a case series of 14 patients. Given the rarity of solitary fibrous tumour, large trials are not feasible. We report the efficacy of this regimen based on a population-based analysis. Methods This was a population-based retrospective, multi-centre analysis using patient data from a provincial cancer registry and treatment database. Cases from June 2006 through October 2016 were identified for patients receiving bevacizumab and temozolomide for locally advanced, recurrent or metastatic solitary fibrous tumour or hemangiopericytoma, which is sometimes used to describe tumours arising from the meninges. The primary outcome was overall response rate. Secondary outcomes included time to response, progression free survival and overall survival estimated using the Kaplan-Meier method. Results Fourteen patients were identified: median age 59 (range 44-70), male 78.6%. Diagnoses were solitary fibrous tumour in 10 (71.4%) and hemangiopericytoma in four (28.6%), with metastatic disease in 10 (72.7%) patients. The most common primary sites were meninges in four (28.6%) and pelvis in three (21.4%) patients. The median follow-up was 15.5 months, with median treatment of four months. Overall response rate was 21.4% (no complete response, 3 partial response), with median time to response of four months. Median progression free survival, six-month progression free survival and overall survival were 17 months, 65.0%, and 45 months, respectively. Conclusions Efficacy of bevacizumab and temozolomide in solitary fibrous tumour appeared to be similar to that previously reported. Our findings confirmed that bevacizumab and temozolomide is an effective and tolerated treatment for this patient population.

Since the introduction of regulatory drug approval guidance on the evaluation of QT interval prolongation, an increasing number of drug monographs has included cautions on the risk of QT prolongation. For example, QT prolongation is mentioned in the Canadian product monographs of 29 drugs commonly seen in oncology practice. This presents two major challenges. First, most guidelines and risk predictive tools for QT prolongation have been developed for hospitalized patients in acute care settings. In contrast, most QT-prolonging oncology drugs are used in medically stable patients in the ambulatory setting. Second, many oncology drugs are unique for their indications and non-QT prolonging alternative agents are often not available. In this review, we will outline an empiric initial approach to ambulatory cancer patients who are treated with oncology drugs which may prolong QT interval. This includes the predictive value of QT prolongation on torsades de pointes, the risk factors of the patients and the drugs, and the limitations of existing guidance in this area.

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