Romanowsky in the 1890s), it gets serially demethylated and forms all the tri-, di-, mono- and non-methyl intermediates, which are Azure B, Azure A, Azure C, and thionine, respectively. When methylene blue is "polychromed" (oxidized in solution or "ripened" by fungal metabolism, as originally noted in the thesis of Dr. It confers a blue color to both nuclei and cytoplasm, and makes the nuclei more visible.
It is sometimes used in cytopathology, in mixtures including Wright-Giemsa and Diff-Quik. It can also be used during gastrointestinal surgeries (such as bowel resection or gastric bypass) to test for leaks. In fistulas and pilonidal sinuses it is used to identify the tract for complete excision. Methylene blue is used as an aid to visualisation/orientation in a number of medical devices, including a Surgical sealant film, TissuePatch. Additionally, methylene blue accelerates the hardening of bone cement, increasing the speed at which bone cement can be effectively applied. Similarly, methylene blue is added to bone cement in orthopedic operations to provide easy discrimination between native bone and cement. In surgeries such as sentinel lymph node dissections, methylene blue can be used to visually trace the lymphatic drainage of tested tissues. Intravenously injected methylene blue is readily released into the urine and thus can be used to test the urinary tract for leaks or fistulas. Methylene blue is also used as a dye in chromoendoscopy, and is sprayed onto the mucosa of the gastrointestinal tract in order to identify dysplasia, or pre-cancerous lesions. This allows the submucosal tissue plane to be identified after the polyp is removed, which is useful in determining if more tissue needs to be removed, or if there has been a high risk for perforation. Methylene blue is used in endoscopic polypectomy as an adjunct to saline or epinephrine, and is used for injection into the submucosa around the polyp to be removed. Dye or stain Human cheek cells stained with methylene blue Methylene blue crystals Matilda Moldenhauer Brooks in San Francisco, although first demonstrated by Bo Sahlin of Lund University, in 1926. Since its reduction potential is similar to that of oxygen and can be reduced by components of the electron transport chain, large doses of methylene blue are sometimes used as an antidote to potassium cyanide poisoning, a method first successfully tested in 1933 by Dr. It is not safe or effective for any medical purpose. Hyoscyamine/hexamethylenetetramine/phenyl salicylate/methylene blue/benzoic acid (trade names Methylphen, Prosed DS) is a drug combination. At high doses, however, methylene blue actually induces methemoglobinemia, reversing this pathway. Methylene blue can reduce the half life of methemoglobin from hours to minutes. Methylene blue, when injected intravenously as an antidote, is itself first reduced to leucomethylene blue, which then reduces the heme group from methemoglobin to hemoglobin. When large amounts of methemoglobin occur secondary to toxins, methemoglobin reductases are overwhelmed. Normally, through the NADH or NADPH dependent methemoglobin reductase enzymes, methemoglobin is reduced back to hemoglobin. Methylene blue is employed as a medication for the treatment of methemoglobinemia, which can arise from ingestion of certain pharmaceuticals, toxins, or broad beans. It is on the World Health Organization's List of Essential Medicines. Methylene blue was first prepared in 1876, by Heinrich Caro. While use during pregnancy may harm the baby, not using it in methemoglobinemia is likely more dangerous. Use often turns the urine, sweat, and stool blue to green in color. Other side effects include serotonin syndrome, red blood cell breakdown, and allergic reactions. Common side effects include headache, vomiting, confusion, shortness of breath, and high blood pressure. Methylene blue is typically given by injection into a vein. It has previously been used for treating cyanide poisoning and urinary tract infections, but this use is no longer recommended. Specifically, it is used to treat methemoglobin levels that are greater than 30% or in which there are symptoms despite oxygen therapy. As a medication, it is mainly used to treat methemoglobinemia by converting/chemically reducing the ferric iron in hemoglobin to ferrous iron. Methylthioninium chloride, commonly called methylene blue, is a salt used as a dye and as a medication.
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