Cholesterol sulphate

Smondyrev AM, Berkowitz ML (2000) Molecular dynamics simulation of dipalmitoylphos-phatidylcholine membrane with cholesterol sulphate, Biophys J, 78 1672-1680... 

Skin barrier functions can be mainly attributed to the outermost layer of mammalian epidermis, the stratum corneum (SC). This region consists of dead, cornified cells embedded in a matrix of extracellular lipids, containing mainly ceramides, cholesterol, cholesterol sulphate and free fatty acids. The SC lipids are organized in a specific lamellar, quasi-crystalline structure, which is critical for optimal skin barrier homeostasis. However, formation of the lamellar structure requires presence of the lipid subclasses in a defined ratio, and ceramides by weight comprise roughly 50% of total SC lipids. The structure and formation of the epidermal lipid barrier is explained in Figure 12.15. 

The gel phase consists of crystalline lipid bilayers alternating with water layers. When the L -phase is cooled through the hydrocarbon chain crystallization temperature, a gel phase can be formed which is usually metastable. There are even amphiphile-water systems which exhibit thermodynamically stable gel phases as the only type of lipid-water phase. One example is the tetradecylamine-water system (Larsson and Al-Mamun, 1973) shown in Fig. 8.17. Other lipids which only give gel phases in their aqueous systems are cholesterol sulphate and cholesterol phosphate (Abrahamsson et al., 1977). The gel phase of tetradecylamine consists of bilayers with vertical chains in the orthorhombic chain packing. At low water content this structure swells to a water layer thickness of 14 A. At very high water concentrations, however, another gel phase with the same lipid bilayers but with a water layer several hundred A thick is formed. The reason for this seems... 

Crystals of cholesterol monohydrate occur in various pathological conditions (Bogren and Larsson, 1961). The crystal structure of cholesterol monohydrate has been determined by Craven (1976). Cholesterol sulphate has been found in marine organisms and can form aqueous bilayer phases of the gel-type (Abrahamsson et al., 1977). 

AmBisome . This is a sterile lyophilised liposomal formulation. Each vial contains 50 mg amphotericin B, 194 mg hydrogenated soybean phosphatidylcholine, 84 mg distearoylphosphatidylglycerol and 52 mg cholesterol. Upon reconstitution with sterile water for injection, small unilamellar liposomes that have a mean diameter of 80-100 nm are formed. Adult dose 1-3 mg/kg daily. Amphocil . This is a sterile lyophilised cofioidal dispersion. Each vial contains 50 or 100 mg amphotericin B and sodium cholesterol sulphate approximately equimolar amount. Upon reconstitution with sterile water for injection it forms a colloidal dispersion. Adult dose 1-4 mg/kg daily. 

A 0-9% salt solution is considered to be isotonic with blood. Other electrolytes present include bicarbonate ions (HCOj ) and small amounts of potassium, calcium, magnesium, phosphate, sulphate and organic acid ions. Included among the complex compounds and present in smaller amounts are phospholipids, cholesterols, natural fats, proteins, glucose and amino acids. Under normal conditions the extracellular body fluid is slightly alkaline with a pH of 7-4. ... 

The most common assay uses 3a-hydroxysteroid dehydrogenase to form the 3-keto bile acid that is trapped by, for example, hydrazine hydrate, causing the reaction to go to completion. The co-factor NAD is reduced stoichiometrically and can be measured by ultraviolet absorption or more commonly by fluorescence at an activation of 345 nm and emission of 450 nm. Use of this enzyme measures all bile acids with a 3a-hydroxyl but not cholesterol, which has a 3p-hydroxyl, and does not measure bile acids with a sulphate or glucuronide group conjugated to the 3a-hydroxyl. 

Urinary diterpenes excretion. Absorption and excretion of the cholesterol-raising coffee diterpenes cafestol and kahweol were observed in nine healthy patients with ileostomies. Ileostomy effluent was collected for 14 hours, and urine was collected for 24 hours. Approximately 70% of the ingested cafestol and kahweol was absorbed. Only small part of the diterpene was excreted as a conjugate of glucuronic acid or sulphate in urine, mean excretion was 1.2% of the ingested amount for cafesterol and 0.4% for kahweol . 

Methyl ethers were applied firstly to the GC of cholesterols [390,391]. They are prepared by the method common for the preparation of ethers, e.g., by treatment with dimethyl sulphate or methyl iodide in the presence of potassium rert.-butoxide (cf., p. 64). Their good chromatographic properties, e.g., on SE-30 and PEGS stationary phases, are usually obtained only after further treatment with a silylating or acylating agent. 

Ferrous sulphate eneapsulated in soy lecithin liposomes has been used to deliver iron. These preparations have improved bioavailability compared to ferrous sulphate directly added in milk and dairy products (Boccio et al. 1997 Uicich et al. 1999). Albaldawi et al. (2005) reported that the addition of encapsulated haem iron in lecithin/cholesterol liposomes resulted in improved rheological properties of bread dough and the sensory properties of baked bread. 

Diagrammatic representation of zone-specific steroid synthesis in the adrenal cortex. All three zones can convert cholesterol into pregnenolone, but because of the presence/absence of certain enzymes, the flow of pregnenolone is preferentially directed to the synthesis of the steroid for which the particular zone is specific. It has not been determined whether the zona fasciculata produces dehydroepiandrosterone (DHEA) and dehydroepiandrosterone sulphate (DHEAS) in physiologically significant amounts. 

Surfactants Nonionic Sorbitan esters Polysorbates Polyoxyethylene alkyl ethers Polyoxyethylene alkyl esters Polyoxyethylene aryl ethers Glycerol esters Cholesterol Anionic Sodium dodecyl sulphate Cationic Cetrimide Benzalkonium chloride... 

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