Water, alcohols, carboxylic acids, and many other hydroxy-containing compounds can be readily deprotonated due to a large difference between the electronegativity of oxygen (3.5) and that of hydrogen (2.1). Hydroxy-containing compounds engage in intermolecular hydrogen bonding increasing the electrostatic attraction between molecules and thus to higher boiling and melting points than found for compounds that lack this functional group. Organic compounds, which are often poorly soluble in water, become water-soluble when they contain two or more hydroxy groups, as illustrated by sugars and amino acid.[2]
The hydroxy group is pervasive in chemistry and biochemistry. Many inorganic compounds contain hydroxyl groups, including sulfuric acid, the chemical compound produced on the largest scale industrially.[3]
hydroxy
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Hydroxyl radicals are highly reactive and undergo chemical reactions that make them short-lived. When biological systems are exposed to hydroxyl radicals, they can cause damage to cells, including those in humans, where they can react with DNA, lipids, and proteins.[5]
The Earth's night sky is illuminated by diffuse light, called airglow, that is produced by radiative transitions of atoms and molecules.[6] Among the most intense such features observed in the Earth's night sky is a group of infrared transitions at wavelengths between 700 nanometers and 900 nanometers. In 1950, Aden Meinel showed that these were transitions of the hydroxyl molecule, OH.[7]
On 26 October 2020, NASA reported definitive evidence of water on the sunlit surface of the Moon, in the vicinity of the crater Clavius (crater), obtained by the Stratospheric Observatory for Infrared Astronomy (SOFIA).[10] The SOFIA Faint Object infrared Camera for the SOFIA Telescope (FORCAST) detected emission bands at a wavelength of 6.1 micrometers that are present in water but not in hydroxyl. The abundance of water on the Moon's surface was inferred to be equivalent to the contents of a 12-ounce bottle of water per cubic meter of lunar soil.[11]
The Chang'e 5 probe, which landed on the Moon on 1 December 2020, carried a mineralogical spectrometer that could measure infrared reflectance spectra of lunar rock and regolith. The reflectance spectrum of a rock sample at a wavelength of 2.85 micrometers indicated localized water/hydroxyl concentrations as high as 180 parts per million.[12]
This LCD supplements but does not replace, modify or supersede existing Medicare applicable National Coverage Determinations (NCDs) or payment policy rules and regulations for Vitamin D; 25 hydroxy, includes fraction(s), if performed. Federal statute and subsequent Medicare regulations regarding provision and payment for medical services are lengthy. They are not repeated in this LCD. Neither Medicare payment policy rules nor this LCD replace, modify or supersede applicable state statutes regarding medical practice or other health practice professions acts, definitions and/or scopes of practice. All providers who report services for Medicare payment must fully understand and follow all existing laws, regulations and rules for Medicare payment for Vitamin D; 25 hydroxy, includes fraction(s), if performed and must properly submit only valid claims for them. Please review and understand them and apply the medical necessity provisions in the policy within the context of the manual rules. Relevant CMS manual instructions and policies may be found in the following Internet-Only Manuals (IOMs) published on the CMS Web site.
History/Background and/or General InformationVitamin D, a group of fat-soluble prohormones, is an essential Vitamin. There are two major types of Vitamin D (Vitamin D2 and Vitamin D3) which are collectively known as calciferol. They are essential for promoting calcium absorption and maintaining adequate serum calcium and phosphate concentrations to enable mineralization of bone and prevent hypocalcemic conditions. Vitamin D2 (ergocalciferol) is obtained from foods of plant origin and vitamin D3 (cholecalciferol) is obtained from foods of animal origin and ultraviolet light-stimulated conversion of 7-dehydrocholesterol in the skin. Vitamin D is stored in the human body as calcidiol (25-hydroxyvitamin D). Serum concentration of 25(OH) D is the best indicator of Vitamin D status.Vitamin D deficiencies are the result of dietary inadequacy, impaired absorption and use, increased requirement, or increased excretion. Vitamin D deficiency can occur when usual intake is lower than recommended levels over a period of time, or when exposure to sunlight is limited. Vitamin D deficiency can also result from the inability of the kidneys to convert the Vitamin D to its active form.There is robust evidence supporting skeletal benefits at a Vitamin D level of 20 ng/mL (50 nmol/L). There is clinical evidence that to achieve non-skeletal benefits of Vitamin D, a level of 30 ng/mL (75 nmol/L) may be required. Currently, the Endocrine Society is endorsing a level of 30 ng/mL (75 nmol/L). Vitamin D deficiency in high risk adults is identified as serum concentration of 25(OH) D
This LCD outlines the indications for Vitamin D, 25-hydroxy. This test is appropriate for assessment of Vitamin D deficiency. Vitamin D, 1,25-dihydroxy is primarily indicated during patient evaluations for hypercalcemia and renal failure. It should not be ordered in addition to Vitamin D, 25-hydroxy for Vitamin D deficiency testing.Please refer to CMS IOM Publication 100-04, Medicare Claims Processing Manual, Chapter 16, Section 120.1 for additional limitations for Vitamin D assay testing.As published in the CMS IOM Publication 100-08, Medicare Program Integrity Manual, Chapter 13, Section 13.5.4, an item or service may be covered by a contractor LCD if it is reasonable and necessary under the Social Security Act Section 1862 (a)(1)(A). Contractors shall determine and describe the circumstances under which the item or service is considered reasonable and necessary.
Refer to the Local Coverage Article: Billing and Coding: Vitamin D; 25 hydroxy, includes fraction(s), if performed, A56841 for documentation requirements, utilization parameters and all coding information.
Vitamin D must go through several processes in your body before your body can use it. The first transformation occurs in the liver. Here, your body converts vitamin D to a chemical known as 25-hydroxyvitamin D, also called calcidiol.
The 25-hydroxy vitamin D test is the best way to monitor vitamin D levels. The amount of 25-hydroxyvitamin D in your blood is a good indication of how much vitamin D your body has. The test can determine if your vitamin D levels are too high or too low.
Your doctor may request a 25-hydroxy vitamin D test for several different reasons. It can help them figure out whether too much or too little vitamin D is causing bone weakness or other abnormalities. It can also monitor people who are at risk for having a vitamin D deficiency.
The 25-hydroxy vitamin D test requires a common blood test. Your healthcare provider will draw blood from a vein in your arm using a needle. A quick finger prick will more than likely provide enough for a blood sample in children and infants.
Countries around the world introduced chloroquine or hydroxychloroquine into guidelines.[26, 27, 28] For example, India quickly directed all frontline healthcare workers and household contacts to take prophylactic hydroxychloroquine.[29] A few days after Trump's initial hydroxychloroquine promotion, President Bolsonaro ordered an increase in production of chloroquine in Brazil.[30]
Abstract:AHAs are organic acids with one hydroxyl group attached to the alpha position of the acid. AHAs including glycolic acid, lactic acid, malic acid, tartaric acid, and citric acid are often used extensively in cosmetic formulations. AHAs have been used as superficial peeling agents as well as to ameliorate the appearance of keratoses and acne in dermatology. However, caution should be exercised in relation to certain adverse reactions among patients using products with AHAs, including swelling, burning, and pruritus. Whether AHAs enhance or decrease photo damage of the skin remains unclear, compelling us to ask the question, is AHA a friend or a foe of the skin? The aim of this manuscript is to review the various biological effects and mechanisms of AHAs on human keratinocytes and in an animal model. We conclude that whether AHA is a friend or foe of human skin depends on its concentration. These mechanisms of AHAs are currently well understood, aiding the development of novel approaches for the prevention of UV-induced skin damage.Keywords: alpha-hydroxy acids; UVB; apoptosis; keratinocyte; glycolic acid
Values of vitamin D vary with exposure to sunlight. The assay measures other vitamin D metabolites, including dihydroxylated metabolites such as 24,25, 25,26, and 1,25 dihydroxy vitamin D; however, since the physiological concentrations of these metabolites are insignificant compared to those of 25-hydroxy vitamin D, the accuracy in assessing vitamin D levels is not compromised. 2ff7e9595c
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