Laxative-free

Iannaccone et al. (2004) examined successfully 203 patients with laxative-free CT colonography. They performed faecal tagging over two days with a total of 200 ml of diatrizoate meglumine and diatrizoate sodium. The patients were also on a low residue diet for two days. They obtained very good results of polyp detection 86% for lesions >6 mm (79 lesions), 95.5% for lesions >8 mm (45 lesions), 100% for lesions >1 cm (24 lesions). 

In these three studies primary 2D read was performed. Adequately reading and interpreting the data sets is an arduous task and needs a lot of experience as with laxative-free CT colonography more residue is present in the colon. For the same reason primary 3D read is impossible. To do so the faecal residue has to be removed or subtracted using dedicated software. 

Callstrom et al. (2001) performed laxative-free CT colonography without dietary restrictions in 58 patients. Faecal tagging was obtained with a combination of iodine and barium administered over one or two days. The best results of tagging were obtained by combining 6x225 ml of a 2.1% w/v barium suspension and 1x225 ml dilute diatrizoate meglumine and diatrizoate sodium. All residue with a density >150 H.U. was electronically labelled. In that way a 100% sensitivity for lesions >1 cm was obtained (5/5 lesions). 

Lefere P, Gryspeerdt S, Baekelandt M et al. (2004) A method to perform laxative-free CT colonography. Am J Roentgenol 183 945-948... 

Lefere P, Gryspeerdt S, Baekelandt M, Dewyspelaere J, van Holsbeeck B (2003) Diverticular disease in CT colonography. Eur Radiol 13 Suppl 4 L62-74 Lefere P, Gryspeerdt S, Baekelandt M, Van Holsbeeck B (2004) Laxative-free CT colonography. Am J Roentgenol 183(4) 945-948... 

Since bowel preparation is recognized as the most uncomfortable step in the workflow of a conventional colonoscopy as well as for CTC (Gluecker et al. 2003), in order to improve patient compliance, new reduced bowel preparation, or laxative-free study protocols, are under evaluation. Because of the presence of fecal/fluid residues, not completely removed by the absence of complete taxation, fecal tagging is mandatory. In terms of examination accuracy, several experiences have shown results similar to protocols including full bowel preparation (Iannaccone et al. 2004 McFarland and Zalis et ak 2004 Lefere et al. 2005 Dachman et al. 2007 Johnson et al. 2007). 

Some laxatives (e.g., bulk-forming agents) contain significant amounts of sodium or sugar and may be unsuitable for salt-restricted or diabetic patients. When low-sodium or sugar-free products are not used, monitor serum concentrations of sodium and glucose as needed with chronic use. 

A quite different aspect of local kinetics is that having to do with changes of charge state, e.g., between H+ and H° or H° and H. Such changes require emission or absorption of electrons or holes. Since the mean free paths of these carriers are large compared with atomic dimensions, it is customary (see for example Lax, 1960) to use a velocity-averaged cross section a as the key descriptor of the rate of a capture reaction such as H+ + e— H°. Explicitly, we write, for this case,... 

Osmotic laxatives (e.g., lactulose, sorbitol) are poorly absorbed or nonabsorbable compounds that draw additional fluid into the GI tract. Lumen osmolality increases, and fluid movement occurs secondary to osmotic pressure. Lactulose is a synthetic disaccharide that is poorly absorbed from the GI tract, since no mammalian enzyme is capable of hydrolyzing it to its monosaccharide components. It therefore reaches the colon unchanged and is metabolized by colonic bacteria to lactic acid and to small quantities of formic and acetic acids. Since lactulose does contain galactose, it is contraindicated in patients who require a galactose-free diet. Metabolism of lactulose by intestinal bacteria may result in increased formation of intraluminal gas and abdominal distention. Lactulose is also used in the treatment of hepatic encephalopathy. 

Kreydiyyeh et al. (2001) provided scientific evidence to confirm the laxative property of parsley, as claimed in folk medicine, and explained its mechanism of action. A perfusion technique was used to measure net fluid absorption from rat colon. The addition of an aqueous extract of parsley seeds to the perfusion buffer, and the omission of sodium, both significantly reduced net water absorption from the colon, as compared with the control. Parsley, added to a sodium-free buffer, did not lead to any further significant change in water absorption as compared with parsley alone suggesting that with parsley, sodium absorption was already inhibited. Since K+ and Cl secretion depends on the activity of the NaKCl2 transporter, the latter was inhibited with furosemide, which increased net water absorption significantly. When parsley and furosemide were... 

Maximum energy conversion efficiencies of (/ lax = 0.1086 have recently been measured and verified for dye-sensitized regenerative cells illuminated with air mass 1.5 simulated solar irradiation [27]. The efficiency of photoelectrosynthetic cells must also include contributions from the free energy stored in the chemical products of the reduction and oxidation reactions. 

The normal range of free inorganic phosphate, in plasma, is expressed as 2.0-4.3 mg phosphorus/1(K) ml. Hyperphosphatemia is defined as the condition where plasma phosphate levels rise above 5.0 mg phosphorus/100 ml. Hyperphosphatemia can result from overuse of laxatives or enemas that contain phosphate. Phosphate enemas are used in the hospital prior to examinations of the intestines for disease, such as colon cancer. However, hyperphosphatemia has occurred in the home situation with accidental drinking of enema formulas. Enema drinking... 

The osmotic laxatives include inorganic salts and the synthetic disaccharide, lactulose, as well as magnesium salts and sodium phosphate. Osmotic agents are largely free of adverse effects, apart from flatulence, cramps, and abdominal discomfort. 

In liquid preparations sorbitol is used as a vehicle in sugar-free formulations and as a stabilizer for drug, vitamin, and antacid suspensions. It has also been shown to be a suitable carrier to enhance the in vitro dissolution rate of indometa-cin. In syrups it is effective in preventing crystallization around the cap of bottles. Sorbitol is additionally used in injectable and topical preparations and therapeutically as an osmotic laxative. 

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