Blood permeation

Gas separation using ethylceUulose hoUow fiber has also recendy become important. A/G Technology is leading this effort. Fluoroaceylated ethylceUulose is reported to have good gas permeation and blood compatibUity (26). 

Blood-brain barrier permeation of 7, among other drugs, was predicted from its three-dimensional molecular structure by a computational method (0OJMC2204). The combination of molecular topological methods using 137 quinolones, including 7 provided an excellent tool for the design of new... 

The blood-brain barrier (BBB) forms a physiological barrier between the central nervous system and the blood circulation. It consists of glial cells and a special species of endothelial cells, which form tight junctions between each other thereby inhibiting paracellular transport. In addition, the endothelial cells of the BBB express a variety of ABC-transporters to protect the brain tissue against toxic metabolites and xenobiotics. The BBB is permeable to water, glucose, sodium chloride and non-ionised lipid-soluble molecules but large molecules such as peptides as well as many polar substances do not readily permeate the battier. 

Polysiloxane based block copolymers have also been examined with respect to their transport properties, because these copolymers are of special interest as membranes in various biomedical applications 376). The combination of good mechanical, dielectric, permeation and film formation properties of siloxane-carbonate segmented copolymers have led to their use as blood oxygenation, dialysis and microelectrode membranes 392 394. ... 

The method of choice for the determination of a- and P-endosulfan in blood, urine, liver, kidney, brain, and adipose tissue is gas chromatography equipped with an electron capture detector (GC/ECD) (Coutselinis et al. 1976 Demeter and Heyndrickx 1979 Demeter et al. 1977 Le Bel and Williams 1986). This is because GC/ECD is relatively inexpensive, simple to operate, and offers a high sensitivity for halogens (Griffith and Blanke 1974). After fractionation of adipose tissue extracts using gel permeation chromatography, detection limits of low-ppb (1.2 ng/g) were achieved for endosulfan and other chlorinated pesticides using GC/ECD (Le Bel and Williams 1986). 

Nonetheless, the few potent alchemical medicines that he did advocate reveal his unorthodox religious views. At the heart of Fludd s alchemy is the recipe for a red elixir which he described as being a catholic, that is, a universal medicine. It was the quintessence of both Nature and of the human soul, being permeated by the Holy Spirit of the resurrected Christ." It was said to be the alchemical equivalent of human blood, a tincture extracted from the red-oil of wheat. 

Cabrera MA, Bermejo M, Perez M and Ramos R. TOPS-MODE approach for the prediction of blood-brain barrier permeation. J Pharm Sci 2004 93 1701-17. 

Ecker GF and Noe CR. In silico prediction models for blood-brain barrier permeation. Curr Med Chem 2004 11 1617-28. 

Narayanan R and Gunturi SB. In silico ADME modelling prediction models for blood-brain barrier permeation using a systematic variable selection method. Bioorg Med Chem 2005 13 3017-28. 

Subramanian G and Kitchen DB. Computational models to predict blood-brain barrier permeation and CNS activity. J Comput Aided Mol Des 2003 17 643-64. 

Abraham MH. The factors that influence permeation across the blood-brain barrier. Eur J Med Chem 2004 39 235-40. 

Haemodialysis is the process of circulating the patient s blood through a machine via tubing composed of a semi-permeable material such that waste products permeate into the dialysing fluid and the blood then returns to the patient Haemodialysis solutions need not be sterile but must be flee flxm heavy bacterial contamination. 

Eischer, H., Gottschlidi, R., Seelig, A. Blood-brain barrier permeation Molecular parameters governing passive diffusion, y. Membr. Biol. 1998, 165, 201-211. 

Luco, J. M., Marchevsky, E. QSAR smdies on blood-brain barrier permeation. Curr. Comput.-Aided Drug Des. 2006, 2, 31-55. 

Crivori, P., Crudani, G., Carrupt, P.-A., Testa, B. Predicting blood-brain barrier permeation from three-dimensional molecular structure. J. Med. Chem. 2000, 43, 2204-2216. 

Sample size may influence the analytical approach, e.g. 0.1 L of milk is easily obtained and extracted, but 10 mL of blood should be sufficient for monitoring purposes, and 5 g of fat is already the upper limit for an efficient fat cleanup by partition or gel permeation chromatography (GPC). 

The simplest case of pharmacokinetics is intravenous injection [1]. In this case the drug is injected directly into the bloodstream. The drug may permeate to different tissues depending on its ability to get across the blood vessel walls and the cellular barriers in the particular tissue targets (Fig. 1). If the drug has small molecular weight and adequate... 

Water Permeation Through a Blood Cell Membrane... 

Clark DE (2005) Computational prediction of blood-brain barrier permeation. In Doherty A (ed) Annual reports in medicinal chemistry. Elsevier, Oxford, p 413... 

Deletion and derangement of small blood vessels Increase permeation to water and some chemicals Decrease clearance into blood stream Decrease absorption ... 

Mahdihassan, S. "Blood as soul, a concept permeating alchemy and primitive religion." In Essays in the history of alchemy, medicine and drugs, ed. S. Mahdihassan, 61-. Hamdard Foundation, 1982. 

While in vivo studies assess absorption rates as process-lumped time constants from blood level versus time data, these rate parameters encompass the kinetics of dosage-form release, GI transit, metabolism, and membrane permeation. The use of isolated tissue and cellular preparations to screen for drug absorption potential and to evaluate absorption rate limits at the tissue and cellular levels has been expanded by the pharmaceutical industry over the past several years. For more detail in this regard, the reader is referred to an article by Stewart et al. [68] for references on these preparations and for additional details on the various experimental techniques outlined below. 

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