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Dogan Hedegaard posted an update 18 days ago
This lower current results in activation of only proximal ganglion cells, provides more focused stimulation and lowers the risk of tissue damage.Electrical stimulation has been used for decades in devices such as pacemakers, cochlear implants and more recently for deep brain and retinal stimulation and electroceutical treatment of disease. However, current spread from the electrodes limits the precision of neural activation, leading to a low quality therapeutic outcome or undesired side-effects. Alternative methods of neural stimulation such as optical stimulation offer the potential to deliver higher spatial resolution of neural activation. Direct optical stimulation is possible with infrared light, while visible light can be used to activate neurons if the neural tissue is genetically modified with a light sensitive ion channel. Experimentally, both methods have resulted in highly precise stimulation with little spread of activation at least in the cochlea, each with advantages and disadvantages. Infrared neural stimulation does not require modification of the neural tissue, but has very high power requirements. Optogenetics can achieve precision of activation with lower power, but only in conjunction with targeted insertion of a light sensitive ion channel into the nervous system via gene therapy. This review will examine the advantages and limitations of optical stimulation of neural tissue, using the cochlea as an exemplary model and recent developments for retinal and deep brain stimulation.A 61-year-old alcoholic male with history of cholecystectomy presented with a 20-year history of recurrent bowel obstruction and a 30 lb weight loss. After numerous attempts at conservative management, exploratory laparotomy was performed, which showed no mechanical cause. Despite no clear etiology, the obstruction persisted and intensified. A follow-up computed tomography scan revealed a small bowel obstruction with concurrent megacolon. A total abdominal colectomy was performed, with ileostomy. Grossly, there was intestinal dilation up to 15 cm with prominent brown discoloration of bowel wall. No strictures or other fixed obstruction were identified. Microscopic examination revealed prominent lipofuscin-like pigment deposition, involving the muscularis propria, muscularis mucosae, and vascular smooth muscle. Histochemical staining was positive for periodic acid-Schiff and negative for iron and calcium, consistent with lipofuscin. The gross and histologic findings fit with brown bowel syndrome. Brown bowel syndrome is a very rare condition characterized by lipofuscin deposits predominantly within the smooth muscle of the muscularis mucosae and/or muscularis propria that imparts a brown color to the bowel. It is generally thought to be a smooth muscle mitochondrial myopathy due to chronic vitamin E deficiency secondary to fat malabsorption syndromes, resulting in free radicals causing peroxidation of unsaturated membrane lipids with accumulation of lipofuscin. Brown bowel syndrome may be seen in patients with alcohol abuse, maldigestion, chronic bowel inflammation, and intestinal lymphangiectasia. this website Our patient’s severe chronic intestinal pseudo-obstruction, low levels of certain fat-soluble vitamins (A, D, and E), significant weight loss and history of cholecystectomy with alcohol abuse correlates with brown bowel syndrome clinically.Foreign body esophagus remains one of the common medical emergencies which may lead to significant morbidity and mortality. Sharp objects, batteries, and elderly with foreign body esophagus should be treated with emergent removal owing to the complications that might ensue. Endoscopic removal is the preferred choice of treatment but for large foreign body, sharp foreign body, and so on, rigid esophagoscopic removal might be more preferable. Foreign body esophagus though an obvious situation might at times be missed. It is important to make an early definitive diagnosis. We report a unique case of missed foreign body (denture) esophagus despite the obvious signs and symptoms. Definitive diagnosis was made only after 6 years due to the lack of definitive diagnostic procedures and expertise. The foreign body was impacted in the mucosal wall of the esophagus requiring Gastric resection and anastomosis (with McKeown procedure). With this we have tried to highlight the pitfalls in the diagnosis and management of foreign body esophagus. We report a case of a 55-year-old female who presented to the Emergency Room with history of progressive dysphagia and odynophagia for 6 years which was aggravated for the past 6 months. A radiological diagnosis was made. It was followed by a failed attempt of endoscopic removal which warranted the surgical removal of the foreign body.Non-neural granular cell tumor was first described in 1991 as an unusual primitive, polypoid variant of the conventional granular cell tumor. To date, this neoplasm remains a rare entity and the cell of origin is uncertain. While the histological features are similar to the conventional granular cell tumor, it represents a distinct entity that is negative for S100 and lacks true nerve sheath differentiation. Here, we describe a case of a 4-year-old male who presented with a painless, soft nodule on his right chest wall that was slowly increasing in size. The mass was excised and sent for pathologic analysis. Microscopic examination reveals spindle and epithelioid cells with vesicular nuclei and prominent granular eosinophilic cytoplasm. Immunohistochemical analysis shows negative staining for S100 and AE1/AE3/PCK26 but is positive for CD68. A diagnosis of a non-neural granular cell tumor was made. We report a rare and diagnostically challenging case in a pediatric patient.Familial adenomatous polyposis (FAP) is an autosomal dominant hereditary precancerous condition caused by germline pathogenetic variants in the tumor suppressor adenomatous polyposis coli (APC) gene. Patients with FAP develop multiple gastrointestinal adenomatous polyps usually at the age of ~20 years, which, if untreated, become cancerous in 100% of cases. Genotype-phenotype associations have been extensively described; however, inter- and intra-familial variability exists. It is crucial to characterize the causative pathogenetic variant in each pedigree in order to develop a cancer prevention program and follow-up strategy for at-risk families. The present report describes a severe case of sporadic FAP that was diagnosed when the patient was ~2 years old. The patient was a carrier of the de novo pathogenic c.4132 C>T (p.Gln1378X) variant. Additionally, the patient was a carrier of the homozygous c.5465 T>A (p.Asp1822Val) polymorphism, inherited from both parents. However, it remains unclear whether or not this polymorphism is involved in the phenotypic manifestation.