Steroids defined

Usually used to detect anabolic steroids. Defined by Thein and Landry ... 

Exhaled nitric oxide was used as the marker of airway inflammation after patients who had asthma were found to have increased levels of exhaled nitric oxide and nitric oxide synthase expression [17]. Exhaled nitric oxide correlated with a response to steroid, defined as change in pulmonary function testing, asthma symptoms, and BHR [18]. Patients who have symptoms of asthma who respond to steroids have higher exhaled nitric oxide than those who do not, implying inadequate anti-inflammatory treatment. The cutoff of exhaled nitric oxide for steroid response was determined to be approximately 48 parts per billion in one study [18], but no standards are widely used. 

Unique names can be assigned to steroids defining composition, constitution, and configuration. The most important carbon skeletons including numberings have been given above a and P refer to the two faces of the steroid nucleus P is the top face as viewed in the orientation shown in Scheme 3.2.2 and a is the underneath face. As a typical example of lUPAC nomenclature, the commercial catabolicum flumethasone is depicted in Scheme 3.2.2. 

In the 1980s, advances in biotechnology had a considerable impact on steroid research. During this period, the mechanism of steroid hormone-activated gene regulation became more clearly defined. These mechanistic studies stiH receive considerable attention in the primary Hterature. 

It is hoped that these volumes will be useful not only to the chemist who wishes to carry out synthesis in the steroid field, but also to the broader group of organic chemists who are interested in carrying out selective and stereo-chemically defined reactions, as well as protective chemistry on extraneous functional groups, during a broad range of synthetic applications. The chapter on the introduction of deuterium and by inference tritium into steroids was included because of the importance of this technique in mechanistic and metabolic studies both in the steroid and nonsteroid field. 

In practice, the scope of the benzilic rearrangement as a tool for the ring contraction of steroids is defined by the availability of a-diketones, or the corresponding diosphenols. 

Lipids are naturally occurring organic molecules that have limited solubility in water and can be isolated from organisms by extraction with nonpolar organic solvents. Fats, oils, waxes, many vitamins and hormones, and most nonprotein cell-meznbrane components are examples. Note that this definition differs from the sort used for carbohydrates and proteins in that lipids are defined by a physical property (solubility) rather than by structure. Of the many kinds of lipids, we ll be concerned in this chapter only with a few triacvlglycerols, eicosanoids, terpenoids, and steroids. 

Kliewer SA, Moore JT, Wade L, Staudinger JL, Watson MA, Jones SA, et al. An orphan nnclear receptor activated by pregnanes defines a novel steroid signalling pathway. Cell 1998 92 73-82. 

By selectively affecting gene transcription and the consequent production of appropriate target mRNAs, the amounts of specific proteins are changed and metabolic processes are influenced. The influence of each of these hormones is quite specific generally, the hormone affects less than 1% of the genes, mRNA, or proteins in a target cell sometimes only a few are affected. The nuclear actions of steroid, thyroid, and retinoid hormones are quite well defined. Most evidence sug-... 

Much of the early work with certified reference materials was linked to the derivation of reference methods and there was a period in which primary or definitive (i.e. very accurate but usually very complex) and secondary (or usable) methods were reported e.g. steroid hormones (Siekmann 1979), creatinine (Siekmann 1985), urea (Welch et al. 1984) and nickel (Brown et al. 1981). Although there are some application areas, such as checking the concentrations of preparations listed in a pharmacopoeia, where a prescribed, defined method has to be used, in practice such work is limited. However, this approach to chemical analysis is no longer widely used and will not be further discussed. The emphasis now is placed on using RMs to demonstrate that a method in use meets analytical criteria or targets deemed to be appropriate for the application and to develop figures of merit (Delves 1984). 

Lipids may be defined as a large group of molecules with a substantial portion of aliphatic or aromatic hydrocarbon. Included are molecules with diverse chemical characteristics, such as the hydrocarbons, soaps, detergents, acylglycerols, steroids, phospholipids, sphin-golipids, and fat-soluble vitamins, and, subsequently, with diverse physical behavior. One of the most important characteristics of lipids from a biological aspect is their behavior in aqueous environments, as all cells exist in an aqueous milieu. In this respect, the lipids range from almost total insolubility to nearly complete solubility. 

There is concern regarding administration of dexamethasone to patients with pneumococcal meningitis caused by penicillin- or cephalosporin-resistant strains, for which vancomycin would be required. Animal models indicate that concurrent steroid use reduces vancomycin penetration into the CSF by 42% to 77% and delays CSF sterilization due to reduction in the inflammatory response.23 Treatment failures have been reported in adults with resistant pneumococcal meningitis who were treated with dexamethasone, but the risk-benefit of using dexamethasone in these patients cannot be defined at this time. Animal models indicate a benefit of adding rifampin in patients with resistant pneumococcal meningitis whenever dexamethasone is used.21,23... 

The mechanisms of corticosteroid receptor regulation of transcription have been elucidated. Both type I and type II corticosteroid receptors are members of a superfamily of ligand-activated transcription factors defined by protein sequence similarity. Included in this superfamily are various other steroid receptors, such as the estrogen receptor, as well as members of the retinoic acid receptor... 

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