Virtual colonoscopy to screen for colorectal cancer.
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Adenoma↗
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Virtual colonoscopy to screen for colorectal cancer.
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Aged↗
Virtual colonoscopy to screen for colorectal cancer.
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Adenoma↗
HTS Technologies--IBC Informa Conference.
In 1997, approximately US $6 billion were spent on worldwide screening technologies. The estimate for the total global market for high-throughput screening (HTS) products and services was about US $1.5 billion (source: Medical and Healthcare Marketplace Guide, 15th Edition, 1999-2000). Genomics and combinatorial chemistry demand a technological shift away from present-day laboratory to fully automated HTS and ultra HTS (uHTS), with over 100,000 compounds screened per day. The potential of new technology in miniaturization and automation will ensure faster and cheaper solutions to discovery. The conference explored the rapidly advancing field of HTS and examined numerous areas of HTS application. Identification and prioritization of viable targets, and the development of 'information rich' screens without reducing screening capacity, are important topics. Furthermore, the essential integration of all these screening, analytical and parallel synthesis systems in one coherent process is considered to be of significant interest. Focused sessions addressed the rapidly advancing areas of ADME (absorption, distribution, metabolism, elimination), toxicity and formulation screening, including virtual 'in silico' screening.
Journal Article↗
Patient experience and preferences toward colon cancer screening: a comparison of virtual colonoscopy and conventional colonoscopy.
BACKGROUND: Virtual colonoscopy has excellent sensitivity for the detection of cancer and polyps greater than 1 cm in diameter. For virtual colonoscopy to succeed as a screening test for colorectal neoplasia, it must be well tolerated and accepted by patients. Patients' experiences with virtual colonoscopy and conventional colonoscopy were assessed and compared. METHODS: Patients referred to the GI clinic for colonoscopy for any indication were recruited to undergo virtual colonoscopy before conventional colonoscopy. Patients were asked to complete a questionnaire twice: after virtual colonoscopy and after completing both tests. Three variables, overall pain, discomfort, and lack of respect, were assessed by using a 7-point Liken scale with higher scores denoting a worse experience. Patients' preferences for virtual colonoscopy versus conventional colonoscopy were determined with a time tradeoff technique. To verify response stability, patients were asked to return an additional questionnaire by mail at 24 hours. RESULTS: Two hundred ninety-five patients completed the questionnaire immediately after the procedures, and 83 patients completed the questionnaire at 24 hours. At both 0 and 24 hours, patients reported more pain, discomfort, and less respect after virtual colonoscopy than conventional colonoscopy (p < 0.01). The overall agreement (Kappa statistic) between times 0 and 24 hours was fair. Patients reported that they preferred conventional colonoscopy and would wait longer for conventional colonoscopy (mean = 4.9 weeks) than undergo a virtual colonoscopy (p < 0.01). CONCLUSIONS: Patients tolerate both virtual colonoscopy and conventional colonoscopy, although they report more pain, discomfort, and less respect undergoing virtual colonoscopy. Efforts to improve patient experience during virtual colonoscopy need to be investigated.
Abdominal Pain↗
Development and screening of a polyketide virtual library for drug leads against a motilide pharmacophore.
A virtual library of macrocyclic polyketide molecules was generated and screened to identify novel, conformationally constrained potential motilin receptor agonists ("motilides"). A motilide pharmacophore model was generated from the potent 6,9-enol ether erythromycin and known derivatives from the literature. The pharmacophore for each molecular conformation was a point in a distance-volume space based on presentation of the putative binding moieties. Two methods, one fragment based method and the other reaction based, were explored for constructing the polyketide virtual library. First, a virtual library was assembled from monomeric fragments using the CHORTLES language. Second, the virtual library was assembled by the in silico application of all possible polyketide synthase enzyme reactions to generate the product library. Each library was converted to low-energy 3D conformations by distance geometry and standard minimization methods. The distance-volume metric was calculated for low-energy conformations of the members of the virtual polyketide library and screened against the enol ether pharmacophore. The goal was to identify novel macrocycles that satisfy the pharmacophore. We identified three conformationally constrained, novel polyketide series that have low-energy conformations satisfying the distance-volume constraints of the motilide pharmacophore.
Combinatorial Chemistry Techniques↗
Screening for colorectal cancer: virtually there.
A national rollout of faecal occult-blood screening, federally funded, is the best approach.
Australia↗
Virtual reality exposure therapy: 150-degree screen to desktop PC.
Virtual reality exposure therapy (VRET) developed using immersive or semi-immersive virtual environments present a usability problem for practitioners. To meet practitioner requirements for lower cost and portability VRET programs must often be ported onto desktop environments such as the personal computer (PC). However, success of VRET has been shown to be linked to presence, and the environment's ability to evoke the same reactions and emotions as a real experience. It is generally accepted that high-end virtual environments (VEs) are more immersive than desktop PCs, but level of immersion does not always predict level of presence. This paper reports on the impact on presence of porting a therapeutic VR application for schizophrenia from the initial research environment of a semi-immersive curved screen to PC. Presence in these two environments is measured both introspectively and across a number of causal factors thought to underlie the experience of presence. Results show that the VR exposure program successfully made users feel they were "present" in both platforms. While the desktop PC achieved higher scores on presence across causal factors participants reported they felt more present in the curved screen environment. While comparison of the two groups was statistically significant for the PQ but not for the IPQ, subjective reports of experiences in the environments should be considered in future research as the success of VRET relies heavily on the emotional response of patients to the therapeutic program.
Adolescent↗
Virtual colonoscopy and colorectal cancer screening.
Colorectal cancer (CRC) is the leading cause of cancer related death in the United States. Virtual colonoscopy is a new method for imaging the colon and has produced promising early results for polyp and cancer detection. The challenge remains to reproduce these favorable results in clinical practice and to evaluate the use of virtual colonoscopy in a purely screening population. Virtual colonoscopy may dramatically improve population participation in screening programs and play a major role in minimizing the impact of CRC.
Colonic Polyps↗
Flavone and isoflavone phytoestrogens are agonists of estrogen-related receptors.
While estrogen-related receptors (ERRalpha, ERRbeta, and ERRgamma) share a high amino acid sequence homology with estrogen receptors (ERs), estrogens are not ligands of ERRs. Structure-function studies from this and other laboratories have revealed that ERRs have small ligand-binding pockets and have provided evidence to show that these receptors can activate gene transcription in a constitutive manner. To address the question as to whether there is any agonist for ERRs, our laboratory recently performed virtual ligand screening on ERRalpha that predicted flavone and isoflavone phytoestrogens to be ligands of this receptor. Our mammalian cell transfection and mammalian two-hybrid experiments revealed that three isoflavones (genistein, daidzein, and biochanin A) and one flavone (6,3',4'-trihydroxyflavone) behaved as agonists of ERRs. These phytoestrogens induced the activity of ERRalpha at concentrations that are comparable to those for the activation of ERalpha and ERbeta. In this study, we also used the results of ERRalpha ligand-binding site mutant, F232A, to verify our ERRalpha hypothetical computer model. Our recent ERR research has determined for the first time that flavone and isoflavone phytoestrogens are agonists of ERRs. In addition, our studies have demonstrated that an approach that combines structure-based virtual screening and receptor functional assays can identify novel ligands of orphan nuclear receptors.
Binding, Competitive↗
Protein Alpha Shape (PAS) Dock: a new gaussian-based score function suitable for docking in homology modelled protein structures.
Protein Alpha Shape (PAS) Dock is a new empirical score function suitable for virtual library screening using homology modelled protein structures. Here, the score function is used in combination with the geometry search method Tabu search. A description of the protein binding site is generated using gaussian property fields like in Protein Alpha Shape Similarity Analysis (PASSA). Gaussian property fields are also used to describe the ligand properties. The overlap between the receptor and ligand hydrophilicity and lipophilicity fields is maximised, while minimising steric clashes. Gaussian functions introduce a smoothing of the property fields. This makes the score function robust against small structural variations, and therefore suitable for use with homology models. This also makes it less critical to include protein flexibility in the docking calculations. We use a fast and simplified version of the score function in the geometry search, while a more detailed version is used for the final prediction of the binding free energies. This use of a two-level scoring makes PAS-Dock computationally efficient, and well suited for virtual screening. The PAS-Dock score function is trained on 218 X-ray structures of protein- ligand complexes with experimental binding affinities. The performance of PAS-Dock is compared to two other docking methods, AutoDock and MOE-Dock, with respect to both accuracy and computational efficiency. According to this study, PAS-Dock is more computationally efficient than both AutoDock and MOE-Dock, and gives a better prediction of the free energies of binding. PAS-Dock is also more robust against structural variations than AutoDock.
Algorithms↗
NMR and in silico screening.
NMR-based screening and virtual, or in silico, screening can be highly complementary and synergistic. NMR-based screening is a rapid and reliable method for validating hits that come from in silico screens. In addition, ligand-binding data derived from NMR-based screens can focus and direct subsequent in silico screening. We will first give a short overview of existing NMR and in silico screening methods, discuss the drawbacks associated with each, and finally present applications that highlight the combination of the two technologies.
Algorithms↗
Options for screening for colorectal cancer.
Unlike other types of cancer, there are several options for screening for colorectal cancer (CRC). The most extensively examined method, faecal occult blood testing (FOBT), has been shown, in three large randomized trials, to reduce mortality from CRC by up to 20% if offered biennally and possibly more if offered every year. Recently published data from the US trial suggest that CRC incidence rates are also reduced by up to 20%, but only after 18 years. In this study, the number of positive slides was associated with the positive predictive value both for CRC and adenomas larger than 1 cm, suggesting that the reduction in CRC incidence was caused by the identification and removal of large adenomas. In this respect, this study supports the concept that removing adenomas prevents CRC. More efficient methods of detecting adenomas include the use of colonoscopy or flexible sigmoidoscopy (FS). Considerable evidence exists from case-control and uncontrolled cohort studies to suggest that endoscopic screening by sigmoidoscopy reduces incidence of distal colorectal cancer. However, in the absence of evidence from a randomized trial, several countries have been reluctant to introduce endoscopic screening. Three trialsare currently in progress (in the UK, Italy and the US) to address this issue. Two of these trials are examining the hypothesis that a single FS screen at around age 55-64 might be a cost-effective and acceptable method for reducing CRC incidence rates. Recruitment and screening are now complete in both studies and the first analysis of results on incidence rates is expected in 2004. Colonoscopy screening at 10-year intervals has recently been endorsed in the US on the basis that the reductions in incidence observed with distal CRC screening can be extrapolated to the proximal colon. However, data are lacking and a pilot study for a trial of the acceptability and efficacy of colonoscopy screening is in progress in the US. It has also been suggested that FOBT testing should be used to detect proximal CRC missed by sigmoidoscopy screening, but the small amount of published data suggest that supplementing FS with FOBT offers very little advantage over FS alone. Other forms of CRC screening are under investigation and represent exciting options for the future. Extraction of DNA from stool is now feasible and a number of research groups have shown high sensitivity for CRC using a panel of DNA markers including mutations in k-ras, APC, p53 and BAT26. Data so far indicate that, with the exception of k-ras, these markers are highly specific and therefore represent a significant improvement over FOBT. Whether these tests will replace or supplement existing methods of screening has yet to be determined. It has been suggested that BAT26, which is a marker of microsatellite instability, a feature of proximal sporadic CRC, might be a useful adjunct to sigmoidoscopy screening. Others have suggested that a test for occult blood should be included with the DNA markers to further increase sensitivity. It is not yet known how sensitive these markers are for adenomas--it is only by detecting adenomas that CRC incidence rates can be reduced. A final exciting new option for screening is virtual colonoscopy (VC), which by screening out people without neoplasia allows colonoscopy to be reserved for patients requiring a therapeutic intervention. The sensitivity of VC for large adenomas and CRC appears to be high, although results vary by centre and there is a steep learning curve. Sensitivity for small adenomas is low, but perhaps it is less essential to find such lesions. Some groups have suggested that virtual colonoscopy might be a useful option for investigating patients who test positive with stool-based screening tests. Whichever CRC screening method is finally chosen (and there is no reason why several methods should not ultimately be available), high quality endoscopy resources will always be required to investigate and treat neoplastic lesions detected.
Adenoma↗
Screening of patients after colectomy: virtual colonography.
BACKGROUND: Virtual colonography is a powerful new method of imaging the entire colon and is useful to assess polyps and diagnose colon cancer. We evaluated virtual colonography in the postoperative screening of patients who had colon cancer. METHODS: Fifty-three patients were examined with virtual colonography 12 to 48 months postoperatively. Forty-four patients had received segmental colectomy with restoration of the gastrointestinal tract, and nine patients underwent abdominoperineal resection and permanent colostomy. After proper cleaning of the colon and distention with air, spiral computed tomographic examination of the abdomen with a slice thickness of 5 mm (table speed [TS] 10 mm, reconstruction interval [RI] 2.5 mm) was performed in the supine and prone positions (including intravenous contrast medium infusion). Images were transferred to a separate workstation (Philips Easy Vision) for postprocessing, three-dimensional rendering, and endoluminal viewing. RESULTS: Eleven recurrences (16.41%) were identified in 10 patients by virtual colonography, but one recurrence was missed. Conventional colonoscopy was incomplete in six cases, and two patients with colostomy refused colonoscopy. In these eight cases (15%), virtual colonoscopy was completed without problems. A second tumor in one patient who had received abdominoperineal resection was demonstrated by virtual colonography, but conventional colonoscopy failed to demonstrate the lesion. Liver metastases were identified in only one patient. CONCLUSIONS: Virtual colonography seems to provide a good alternative in the follow-up of patients after colectomy. The technique is effective in the diagnosis of locoregional recurrences and distant metastases and is well accepted by patients, and results are equal to those of the conventional colonoscopy.
Adult↗
A fast algorithm for searching for molecules containing a pharmacophore in very large virtual combinatorial libraries.
We present a new algorithm for identifying molecules that display a pharmacophore, or in general a structural motif, by efficiently constructing and screening huge virtual combinatorial libraries of diverse compounds. The uniqueness of this algorithm is its ability to build and screen libraries of ca. 10(18) 3D molecular conformations within a reasonable time scale, thereby increasing the chemical space that can be virtually screened by many orders of magnitude. The algorithm may be used to design new molecules that display a desired pharmacophore on predefined sets of chemical scaffolds. This is demonstrated herein by screening a library of backbone cyclic peptides to find candidate peptido- and proteinomimetics.
Algorithms↗
Pitfalls and feasibility of a protocol of virtual colonography designed for the screening of colo-rectal pre-cancerous lesions.
PURPOSE: To evaluate the pitfalls occurring during the virtual colonoscopy examination performed with a protocol designed for screening purposes. MATERIALS AND METHODS: 40 patients underwent a spiral CT for virtual colonoscopic evaluation with the following parameters: collimation 3 mm, feed 6 mm.rot(-1), pitch 2 and increment 1 mm in supine position. Virtual colonography examination was carried out using a dedicated workstation equipped with a software which allows to generate 3D images and virtual endoscopic views. Colon distension, fluid and fecal material were assessed on a 3 point scale. RESULTS: Distension score was 0.50. Left colon and cecum score was 0.32 while in the sigmoid and rectum the score was worse with 0.86. Fluid and fecal residues scores were 0.31 and 0.19 respectively. On almost half of the patients additional scans would be necessary. The main cause of additional scans is suboptimal intestinal preparation and colon distension. CONCLUSION: The use of virtual colonoscopy for screening purposes will be possible through the further technical development and with the optimisation of the protocols, particularly by the improvement of colon cleansing and distension.
Adult↗
Interrupting the adenoma-carcinoma sequence: screening for adenomas and cancer, now and in the future.
Screening for colorectal cancer is only beginning to receive the attention it deserves. As screening emerges into the mainstream and utilization increases, competing technologies will battle to assume a greater percentage of the market share of testing. In this review, the standards and principles with which screening tests are evaluated are outlined. Current modalities for screening, including fecal occult blood testing (FOBT), flexible sigmoidoscopy, colonoscopy, barium enema, and the combination of FOBT with sigmoidoscopy, are discussed and critically reviewed. New techniques and technologies for screening, including virtual colonoscopy and molecular methods of screening stool, are previewed. Increased attention on screening and the competition for supremacy among the modalities undergoing evaluation make the prospects for a continued diminution in colorectal cancer mortality promising.
Adenoma↗
Virtual colonoscopy: a new screening tool for colorectal cancer?
One of the new forays into the field of medical imaging is the 3-D computer imaging. Thanks to new and more performant computer processing and 3-D rendering methods it is nowadays possible to generate high resolution images of the inner surface of the colon based on CT and MR images. This article reviews the current status and research directions of virtual colonoscopy and its possible eligibility of becoming a new tool for colorectal screening.
Colonography, Computed Tomographic↗