Polyp Measurement

Pickhardt PJ, Lee AD, McFarland EG et al (2005) Linear polyp measurement at CT colonography in vitro and in vivo comparison of two-dimensional and three-dimensional displays. Radiology 236 872-878 Pickhardt PJ, Taylor AJ, Gopal DV (2006) Surface visualization at 3D endoluminal CT colonography degree of coverage and implications for polyp detection. Gastroenterology 130 1582-1587... 

The progressive transformation of adenomatous polyps to invasive adenocarcinoma has been characterized as the adenoma carcinoma sequence (Muto 1975). However, because the prevalence of undetected cancer in an asymptomatic screening population is very low at ca.1%, colon polyp size is widely accepted as a surrogate end point for outcomes assessment in colorectal cancer screening programs. Thus, the concept of the advanced adenoma has been developed which is defined as an adenomatous polyp measuring 10 mm or greater... 

The content of long-chain PolyPs may be estimated by measuring the metachromatic effect in the absorption spectrum of toluidine blue (Chernysheva et al., 1971 Leitao et al., 1995 Lorenz and Schroder, 1999). Toluidine blue in an aqueous solution exhibits a concentration-dependent absorption spectrum due to a monomer (A.max, 632 nm)-dimer O.max, 590 nm) equilibrium. The PolyP induced the maximal shift of the absorption spectrum to 545 nm. Nucleic acids also induce metachromasia, but with a shift of about 570 nm with DNA and 590 nm with RNA. Figure 2.3 demonstrates the typical absorption spectra of toluidine blue and toluidine blue with different preparations of PolyPs (Chernysheva etal., 1971). 

The first method of enzymatic PolyP assay was proposed by Clark et al. (1986). In this technique, PolyPs were determined by polyphosphate glucokinase obtained from Pro-pionibacterium shermanii. Glucose-6-phosphate dehydrogenase reduced NADP through utilization of the formed glucose-6-phosphate, and the increase in NADPH concentration was measured. 

The effect of CCCP on NMR-detected PolyP was investigated in S. cerevisiae grown on lactate (Beauvoit el al., 1991). The cells were incubated in a resting medium in aerobiosis with lactate or glucose or in anaerobiosis with glucose. For each case, in vivo 31P NMR spectroscopy was used to measure the levels of phosphorylated compounds. A spontaneous PolyP breakdown occurred in anaerobiosis and in the absence of CCCP. In aerobiosis, PolyP hydrolysis was induced by the addition of either CCCP or a vacuolar membrane ATPase-specific inhibitor, bafilomycin Al (Beauvoit el al., 1991). 

The intracellular levels of short- and long-chain PolyPs were measured by means of polyphosphate glucokinase assay in Leishmania major promastigotes incubated in a... 

In the healthy population, the upper limit of CEA is about 3 ilg/L for nonsmokers and 5pg/L for smokers. Because the level of CEA measured is method dependent, values should always be compared using the same method. When changing methods, aU patients being monitored should be tested in parallel using both the old and new methods. CEA level is elevated in some patients having benign conditions, such as cirrhosis (45%), pulmonary emphysema (30%), rectal polyps (5%), benign breast disease (15%), and ulcerative colitis (15%). 

To give a specific example, the advantages of styrene as a substrate for peroxyl radical trapping antioxidants are well known" (i) Its rate constant, kp, for chain propagation is comparatively large (41 M s at 30 °C) so that oxidation occurs at a measurable, suppressed rate during the inhibition period and the inhibition relationship (equation 14) is applicable (ii) styrene contains no easily abstractable H-atom so it forms a polyper-oxyl radical instead of a hydroperoxide, so that the reverse reaction (equation 21), which complicates kinetic studies with many substrates, is avoided and (iii) the chain transfer reaction (pro-oxidant effect, equation 20) is not important with styrene since the mechanism is one involving radical addition of peroxyls to styrene. 

Age-Dependent Model Parameters. Multistage models can be used to evaluate the effects of carcinogens on cancer risk, by assuming that the model parameters are functions of the exposure dose at any particular age. Similarly, multistage models can also be used to evaluate the effects of preventive measures on cancer risk—for example, the use of nonsteroidal anti-inflammatory drugs as a preventive measure to reduce the risk of polyps in the colon. 

Polyp detection in virtual colonography polyps are characterized by a mushroom-like extrusion of the colon wall, and can be detected by their shape they exhibit higher local 3D curvature" ( Gaussian curvature ) properties. These can be detected with methods from differential geometry (the theory of shapes and how to measure and characterize them), and highlighted as, e.g. colored areas as attention foci for further inspection. 

Burling D, Halligan S, Roddie ME et al (2005) Computed tomography coionography automated diameter and volume measurement of colonic polyps compared with a manual technique-in vitro study. J Comput Assist... 

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