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The Follow-Up Metabolic Medicine Hospital Consultation
Published in Michael M. Rothkopf, Jennifer C. Johnson, Optimizing Metabolic Status for the Hospitalized Patient, 2023
Michael M. Rothkopf, Jennifer C. Johnson
There are three forms of vitamin B6: pyridoxine, pyridoxal and pyridoxamine. All three can be converted to the active forms, pyridoxal phosphate (PLP) and pyridoxamine phosphate (PMP). Plasma PLP levels are usually the preferred method of testing vitamin B6 status. Urinary metabolites and erythrocyte enzymatic activity can also be examined.
Additional Supplements That Support Glycemic Control and Reduce Chronic Inflammation
Published in Robert Fried, Richard M. Carlton, Type 2 Diabetes, 2018
Robert Fried, Richard M. Carlton
A number of studies have found that supplementation of vitamin B6 is beneficial in Type 2 diabetes. Vitamin B6 is a water-soluble vitamin that is naturally present in many foods and available as a dietary supplement. It is the generic name for six compounds with vitamin B6 activity: pyridoxine, an alcohol; pyridoxal, an aldehyde; pyridoxamine, which contains an amino group; and their respective 5-phosphate esters. Pyridoxal 5 phosphate (P-5-P/PLP) and pyridoxamine 5 phosphate (PMP) are the active coenzyme forms of vitamin B6 (McCormick. 2006).
Vitamin B6 and Other Inhibitors of Glucocorticoid Receptor Function and Cell Death of B16 Melanoma Cells
Published in Maryce M. Jacobs, Vitamins and Minerals in the Prevention and Treatment of Cancer, 2018
Gerald Litwack, Noreen M. Robertson, Andrew B. Maksymowych, Mahmut Celiker
In 1977 and 1978,1–6 we provided the first evidence that pyridoxal phosphate, the biologically active form of vitamin B6, interfered with the ability of the activated (DNA-binding form) glucocorticoid receptor to interact with DNA, thus opening the possibility that the cellular level of pyridoxal phosphate might regulate the functioning of the receptor mechanism. The precursor or pyridoxal phosphate is dietary vitamin B6, pyridoxine. This is metabolized to pyridoxal phosphate in two steps, the phosphorylation of pyridoxine to form pyridoxine phosphate and its subsequent oxidation to pyridoxal by a riboflavin catalyzed enzymic reaction.7 Pyridoxal, an alternative form of vitamin B6 can enter the cell and be converted to pyridoxal phosphate by pyridoxal kinase and ATP in a single step. Classically, pyridoxal phosphate is known to form a Schiff base with proteins through a side chain amino group of a lysine residue.8 Thus, it appeared that not only was pyridoxal phosphate able to form a Schiff base with lysine residues in the DNA binding domain and at or near the steroid binding site of the glucorticoid receptor, but it was likely that the dietary level of vitamin B6 could influence the cellular level of pyridoxal phosphate and exert some control over the glucocorticoid receptor mechanism that mediates stress adaptation at the cellular level.
Chromosomal microarray and exome sequencing in unexplained early infantile epileptic encephalopathies in a highly consanguineous population
Published in International Journal of Neuroscience, 2023
Dilsad Turkdogan, Ayberk Turkyilmaz, Gunes Sager, Gulten Ozturk, Olcay Unver, Merve Say
Patient #8 with a de novo likely pathogenic variant of SLC16A2 associated with Allan-Herndon-Dudley syndrome (OMIM: #300523) shared reported features, including generalized hypotonia, attacks of severe generalized dystonia and dysconjugate eye movements, and abnormalities of thyroid tests, except dsymorphisms and cerebral white matter abnormalities. The posture abnormality and eye movements dramatically resolved after pyridoxal phosphate treatment. Epilepsy/EIEE has not been reported in Allan-Herndon-Dudley syndrome so far. The present case also had maternal monoallelic variant of DMN1 associated with EIEE 31 (OMIM: #616346). This novel variant was described as likely pathogenic by ACMG criteria and disease causing or damaging by prediction tools. Although we are unaware of data on penetrance rate of DMN1, the possible effect of the variant on epilepsy phenotype could not be completely eliminated.
Mental energy: plausible neurological mechanisms and emerging research on the effects of natural dietary compounds
Published in Nutritional Neuroscience, 2021
Patrick J. O’Connor, David O. Kennedy, Stephen Stahl
In addition to their role in oxidative metabolism, B vitamins are important for one-carbon metabolism and neurochemical synthesis and regulation [125]. Pyridoxal phosphate (vitamin B6) is a rate-limiting cofactor in synthesizing neurotransmitters (e.g. serotonin, GABA). Vitamin B6 deficiencies downregulate GABA and serotonin synthesis, causing disruptions in behavior (e.g. sleep) and physiology (e.g. cardiovascular function; hypothalamus-pituitary control of hormone excretion) that could influence mental energy [125]. Folate and vitamins B2, B3, B6, and B12 are critical to producing neurotransmitters through the folate and methionine cycles (Figure 3). These processes are important for synthesizing and regenerating tetrahydrobiopterin, an essential cofactor that converts amino acids to serotonin, melatonin, dopamine, and noradrenaline, which are pivotal for synthesizing the vasodilatory molecule nitric oxide [125]. Vitamin C acts as a free radical scavenger in the citric acid cycle and central nervous system and is highly expressed in neuronal tissue, acting as a modulator of neurotransmitters including dopamine, glutamate, and acetylcholine [126].
Targeting the gut microbial metabolic pathway with small molecules decreases uremic toxin production
Published in Gut Microbes, 2020
Yingyi Wang, Jianping Li, Chenkai Chen, Jingbo Lu, Jingao Yu, Xuejun Xu, Yin Peng, Sen Zhang, Shu Jiang, Jianming Guo, Jinao Duan
The TnaA enzymatic reaction was performed as described earlier52,53 with minor changes. E. coli were collected by centrifugation at 10,000 rpm (4°C) for 3 min and resuspended in 0.5 mL (equal to the culture volume) phosphate buffer solution (0.2 M; pH 7.2). Bacteria were frozen at −80°C and thawed in a refrigerator. This freeze thaw cycle was repeated three times, then bacteria were further lysed by ultrasonification at 500 W with a 3 s on, 10 s off pulse rate. This was repeated 5 to 7 times and cell lysates were subsequently centrifuged at 4,500 rpm (4°C) for 10 min. The supernatant was incubated with 0.1 mL pyridoxal phosphate (100 μg/mL) for 10 min under anaerobic conditions at 37°C. Subsequently, 0.1 mL tryptophan (0.5 M) was added to the samples which were left to incubate at 37°C for 30 and 60 min. Next, triple acetonitrile was added and mixed thoroughly to terminate the reaction and the samples were centrifuged at 12,000 rpm for 10 min. The supernatants were used to measure the concentration of indole by HPLC-FLD. As reported in the literature,43,53,54 the units of TnaA enzyme activity were calculated as follows: