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Tetrahydrobiopterin (BH 4, THB), also known as sapropterin (), [5] [6] is a cofactor of the three aromatic amino acid hydroxylase enzymes, [7] used in the degradation of amino acid phenylalanine and in the biosynthesis of the neurotransmitters serotonin (5-hydroxytryptamine, 5-HT), melatonin, dopamine, norepinephrine (noradrenaline), epinephrine (adrenaline), and is a cofactor for the ...
Tetrahydrobiopterin deficiency (THBD, BH 4 D) is a rare metabolic disorder that increases the blood levels of phenylalanine.Phenylalanine is an amino acid obtained normally through the diet, but can be harmful if excess levels build up, causing intellectual disability and other serious health problems.
BH4 is the principal active cofactor. BH4 synthesis occurs through two principal pathways; the de novo pathway involves three enzymatic steps and proceeds from GTP, while the salvage pathway converts sepiapterin to BH4 using dihydrofolate reductase. [4] In addition, BH2 is recycled to BH4 by dihydrobiopterin reductase.
Ball-and-stick model of the tetrahydroborate anion, [BH 4] −. Borohydride refers to the anion [B H 4] −, which is also called tetrahydridoborate, and its salts. [1] Borohydride or hydroborate is also the term used for compounds containing [BH 4−n X n] −, where n is an integer from 0 to 3, for example cyanoborohydride or cyanotrihydroborate [BH 3 (CN)] − and triethylborohydride or ...
Cardiac shunts may be described as right-to-left, left-to-right or bidirectional, or as systemic-to-pulmonary or pulmonary-to-systemic.; Cerebral shunt: In cases of hydrocephalus and other conditions that cause chronic increased intracranial pressure, a one-way valve is used to drain excess cerebrospinal fluid from the brain and carry it to other parts of the body.
The location of the shunt is determined by the neurosurgeon based on the type and location of the blockage causing hydrocephalus. All brain ventricles are candidates for shunting. The catheter is most commonly placed in the abdomen but other locations include the heart and lungs. [10] Shunts can often be named after the route used by the ...
Each of the types of shunts listed above can be composed of a tube or catheter and various types of valves, although they can just be composed of the tubing or catheter. Below is a list of valves that are used in lumbar–peritoneal shunts (LP shunts) and Cerebral shunts (for a more detailed list of the types of valves see type of valves): Delta
Sodium borohydride, also known as sodium tetrahydridoborate and sodium tetrahydroborate, [5] is an inorganic compound with the formula Na B H 4 (sometimes written as Na[BH 4]).It is a white crystalline solid, usually encountered as an aqueous basic solution.