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18-Hydroxycortisol
18-Hydroxycortisol is an endogenous steroid, a metabolite of cortisol. Clinical significance 18-hydroxycortisol has been proposed as a biomarker for certain diseases. In humans, 18-hydroxycortisol has no biological activity on glucocorticoid or mineralocorticoid receptors. In healthy subjects, the biosynthesis of 18-hydroxycortisol is low. The highest synthesis of 18-hydroxycortisol was found in certain cases of hypertension like in type 1 familial hyperaldosteronism (glucocorticoid-curable hyperaldosteronism) and type 3 familial hyperaldosteronism, where the adrenal glands are enlarged up to six times their normal size. Increased synthesis is also found in patients with aldosterone-producing adenomas. ACTH stimulation test increases urinary excretion of 18-hydroxycortisol, and dexamethasone inhibits the excretion. Biosynthesis In patients with familial hyperaldosteronism type 1, there is a genetic crossover between specific regions of the CYP11B1 and CYP11B2 genes. This cro ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
18-Oxocortisol
18-Oxocortisol is an endogenous steroid, a metabolite of cortisol. Clinical significance 18-Oxocortisol has been proposed as a biomarker for certain diseases. In humans, 18-oxocortisol has no biological activity on glucocorticoid or mineralocorticoid receptors. In healthy subjects, the biosynthesis of 18-oxocortisol is low. The highest synthesis of 18-oxocortisol was found in certain cases of hypertension like in type 1 familial hyperaldosteronism (glucocorticoid-curable hyperaldosteronism) and type 3 familial hyperaldosteronism, where the adrenal glands are enlarged up to six times their normal size. Increased synthesis is also found in patients with aldosterone-producing adenomas. ACTH stimulation test increases urinary excretion of 18-oxocortisol, and dexamethasone inhibits the excretion. The measurement of 18-oxocortisol using liquid chromatography tandem mass spectrometry has demonstrated its usefulness in distinguishing between unilateral and bilateral forms of primary aldo ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
6β-Hydroxycortisol
6β-Hydroxycortisol is an endogenous steroid. In humans, it is a metabolite of cortisol produced by cytochrome p450-3A monooxygenases, mainly, 6β-hydroxysteroid dehydrogenase (CYP3A4). 6β-hydroxycortisol is used as a biomarker of 6β-hydroxysteroid dehydrogenase (CYP3A4) activity. Drugs that induce CYP3A4 may accelerate cortisol clearance, by accelerating cortisol conversion to 6β-hydroxycortisol, and vice versa: drugs that inhibit CYP3A4 can slow down cortisol clearance, as they reduce the conversion of cortisol to 6β-hydroxycortisol. Biological role Although the exact role of 6β-hydroxycortisol in the human body is not fully understood, it is believed to play an important role in the metabolism and clearance of cortisol. 6β-hydroxycortisol is a metabolite of cortisol: the enzyme 6β-hydroxysteroid dehydrogenase (CYP3A4) catalyzes the formation of 6β-hydroxycortisol from cortisol in the liver and other tissues; the resulting 6β-hydroxycortisol is excreted in urine. 6β-hyd ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Steroid 11β-hydroxylase
Steroid 11β-hydroxylase, also known as steroid 11β-monooxygenase, is a steroid hydroxylase found in the zona glomerulosa and zona fasciculata of the adrenal cortex. Named officially the cytochrome P450 11B1, mitochondrial, it is a protein that in humans is encoded by the ''CYP11B1'' gene. The enzyme is involved in the biosynthesis of Adrenal gland, adrenal corticosteroids by catalyzing the addition of hydroxyl groups during oxidation reactions. Gene The ''CYP11B1'' gene encodes 11β-hydroxylase, a member of the cytochrome P450 superfamily of enzymes. The cytochrome P450 proteins are monooxygenases that catalyze many reactions involved in drug metabolism and synthesis of cholesterol, steroids and other lipids. The product of this CYP11B1 gene is the 11β-hydroxylase protein. This protein localizes to the mitochondrial inner membrane and is involved in the conversion of various steroids in the adrenal cortex. Transcript variants encoding different isoforms have been noted for th ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
18-Hydroxycorticosterone
18-Hydroxycorticosterone is an endogenous steroid. It is a derivative of corticosterone. Function 18-Hydroxycorticosterone serves as an intermediate in the synthesis of aldosterone by the enzyme aldosterone synthase in the zona glomerulosa. It is also an intermediate in the biosynthesis of corticosterone. It spontaneously and reversibly converts to various less polar forms and derivatives, some of which serve as precursors to aldosterone or corticosterone. Specifically, 21-hydroxy-11,18-oxido-4-pregnene-3,20-dione (18-DAL) is hydroxylated to aldosterone in the presence of malate and NADP+ at pH 4.8, indicating that 18-DAL acts as a metabolic intermediate between 18-hydroxycorticosterone and aldosterone. Corticosterone is a mediate precursor in this biosynthesis pathway, with 18-hydroxycorticosterone serving as an intermediate between corticosterone and aldosterone. See also * 18-Hydroxycortisol * Aldosterone synthase Aldosterone synthase, also called steroid 18-hydroxylase, c ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Familial Hyperaldosteronism
Familial hyperaldosteronism is a group of inherited conditions in which the adrenal glands, which are small glands located on top of each kidney, produce too much of the hormone aldosterone. Excess aldosterone causes the kidneys to retain more salt than normal, which in turn increases the body's fluid levels and causes high blood pressure. People with familial hyperaldosteronism may develop severe high blood pressure, often early in life. Without treatment, hypertension increases the risk of strokes, heart attacks, and kidney failure. There are other forms of hyperaldosteronism that are not inherited. This condition is inherited in an autosomal dominant pattern, which means one copy of the altered gene in each cell is sufficient to cause the disorder. The various types of familial hyperaldosteronism have different genetic causes. It is unclear how common these diseases are. All together they appear to make up less than 1% of cases of hyperaldosteronism. Types Familial hyper ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
CYP11B2
Aldosterone synthase, also called steroid 18-hydroxylase, corticosterone 18-monooxygenase or P450C18, is a steroid hydroxylase cytochrome P450 enzyme involved in the biosynthesis of the mineralocorticoid aldosterone and other steroids. The enzyme catalyzes sequential hydroxylations of the steroid angular methyl group at C18 after initial 11β-hydroxylation (the enzyme has steroid 18-hydroxylase activity as well as steroid 11 beta-hydroxylase activity). It is encoded by the gene in humans. Aldosterone synthase is a protein which is only expressed in the zona glomerulosa of the adrenal cortex and is primarily regulated by the renin–angiotensin system. It is the sole enzyme capable of synthesizing aldosterone in humans and plays an important role in electrolyte balance and blood pressure. Genetics Aldosterone synthase is encoded on chromosome 8q22 by the ''CYP11B2'' gene. The gene contains 9 exons and spans roughly 7000 base pairs of DNA. ''CYP11B2'' is closely related with '' ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Cortisol
Cortisol is a steroid hormone in the glucocorticoid class of hormones and a stress hormone. When used as medication, it is known as hydrocortisone. Cortisol is produced in many animals, mainly by the ''zona fasciculata'' of the adrenal cortex in an adrenal gland. In other tissues, it is produced in lower quantities. By a Circadian rhythm, diurnal cycle, cortisol is released and increases in response to Stress (biology), stress and a low Blood sugar, blood-glucose concentration. It functions to increase blood sugar through gluconeogenesis, suppress the immune system, and aid in the metabolism of calories. It also decreases bone formation. These stated functions are carried out by cortisol binding to glucocorticoid or mineralocorticoid receptors inside a cell, which then bind to DNA to affect gene expression. Health effects Metabolic response Metabolism of glucose Cortisol plays a crucial role in regulating glucose metabolism and promotes gluconeogenesis (glucose synthes ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Aldosterone
Aldosterone is the main mineralocorticoid steroid hormone produced by the zona glomerulosa of the adrenal cortex in the adrenal gland. It is essential for sodium conservation in the kidney, salivary glands, sweat glands, and colon. It plays a central role in the homeostatic regulation of blood pressure, plasma sodium (Na+), and potassium (K+) levels. It does so primarily by acting on the mineralocorticoid receptors in the distal tubules and collecting ducts of the nephron. It influences the reabsorption of sodium and excretion of potassium (from and into the tubular fluids, respectively) of the kidney, thereby indirectly influencing water retention or loss, blood pressure, and blood volume.Marieb Human Anatomy & Physiology 9th edition, chapter:16, page:629, question number:14 When dysregulated, aldosterone is pathogenic and contributes to the development and progression of cardiovascular and kidney disease. Aldosterone has exactly the opposite function of the atrial nat ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Hydroxylation
In chemistry, hydroxylation refers to the installation of a hydroxyl group () into an organic compound. Hydroxylations generate alcohols and phenols, which are very common functional groups. Hydroxylation confers some degree of water-solubility. Hydroxylation of a hydrocarbon is an oxidation, thus a step in degradation. Biological hydroxylation In biochemistry, hydroxylation reactions are often facilitated by enzymes called hydroxylases. These enzymes insert an O atom into a bond. Typical stoichiometries for the hydroxylation of a generic hydrocarbon are these: : : Since itself is a slow and unselective hydroxylating agent, catalysts are required to accelerate the pace of the process and to introduce selectivity. Hydroxylation is often the first step in the degradation of organic compounds in air. Hydroxylation is important in detoxification since it converts lipophilic compounds into water-soluble (hydrophilic) products that are more readily removed by the kidneys or liver ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Biosynthesis
Biosynthesis, i.e., chemical synthesis occurring in biological contexts, is a term most often referring to multi-step, enzyme-Catalysis, catalyzed processes where chemical substances absorbed as nutrients (or previously converted through biosynthesis) serve as enzyme substrate (chemistry), substrates, with conversion by the living organism either into simpler or more complex Product (chemistry), products. Examples of biosynthetic pathways include those for the production of amino acids, lipid membrane components, and nucleotides, but also for the production of all classes of biological macromolecules, and of acetyl-coenzyme A, adenosine triphosphate, nicotinamide adenine dinucleotide and other key intermediate and transactional molecules needed for metabolism. Thus, in biosynthesis, any of an array of Chemical compound, compounds, from simple to complex, are converted into other compounds, and so it includes both the catabolism and anabolism (building up and breaking down) of comple ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Adrenocorticotropic Hormone
Adrenocorticotropic hormone (ACTH; also adrenocorticotropin, corticotropin) is a polypeptide tropic hormone produced by and secreted by the anterior pituitary gland. It is also used as a medication and diagnostic agent. ACTH is an important component of the hypothalamic-pituitary-adrenal axis and is often produced in response to biological stress (along with its precursor corticotropin-releasing hormone from the hypothalamus). Its principal effects are increased production and release of cortisol and androgens by the zona fasiculata and zona reticularis, respectively. ACTH is also related to the circadian rhythm in many organisms. Deficiency of ACTH is an indicator of secondary adrenal insufficiency (suppressed production of ACTH due to an impairment of the pituitary gland or hypothalamus, cf. hypopituitarism) or tertiary adrenal insufficiency (disease of the hypothalamus, with a decrease in the release of corticotropin releasing hormone (CRH)). Conversely, chronically e ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
