Total laryngectomy results in a permanent disconnection of the upper and lower airways. Thus, the upper airways are bypassed and can no longer condition, humidify, and filter the inhaled air, leading to damage of the tracheobronchial epithelium. There is little scientific information available about the effects of tracheostoma breathing and the degree of mucosal damage in laryngectomized patients. The aims of this study were to determine the histopathologic findings and investigate the potential impact of using a heat and moisture exchanger (HME) on the tracheal epithelium in long-term tracheostomy patients. Tracheal mucosal biopsies were taken from a total of 70 patients. Specimens were stained with hematoxylin and eosin and examined by a light microscope. Normal pseudostratified ciliated columnar epithelium was found in only 9 (12.9%) cases; while, 17 (24.3%) cases had some degree of basal cell hyperplasia. Squamous metaplasia was the most common finding (50%). Pre-invasive lesions (mild and moderate squamous dysplasia) were found in only one patient who used an HME, and in eight (11.4%) non-users. Although the HME cannot completely restore the physiological functions of the upper respiratory track, it delivers a better quality of air to the lower airways and has a positive effect on tracheal mucosa.

Malignant gliomas are among the deadliest primary brain tumors. Despite multimodal therapy and advances in chemotherapy, imaging, surgical and radiation techniques, these tumors remain virtually incurable. Glioma stem cells may be responsible for resistance to traditional therapies and tumor recurrence. Therefore, elimination of glioma stem cells may be crucial for achieving therapeutic efficacy. Metformin, a small molecule drug widely used in the therapy of type 2 diabetes, has shown significant anti-tumor effects in patients with breast cancer and prostate cancer. Recent preclinical data suggest that metformin also has therapeutic effects against glioma. Here we review the markers and hallmarks of glioma stem cells, and the molecular mechanisms involved in therapeutic targeting of glioma stem cells by metformin.

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