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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 ...
Google Maps is available as a mobile app for the Android and iOS mobile operating systems. The first mobile version of Google Maps (then known as Google Local for Mobile) was launched in beta in November 2005 for mobile platforms supporting J2ME. [191] [192] [193] It was released as Google Maps for Mobile in 2006. [194]
Early clinical testing of ShuntCheck found that functioning shunts flow intermittently, which meant that a ShuntCheck reading of “Flow NOT Confirmed” did not necessarily indicate a shunt problem. [ 2 ] [ 16 ] This discovery led to the development of the ShuntCheck Micro-Pumper, a handheld device which vibrates the shunt valve, generating a ...
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
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.