Search PubMed⌕ Search

SEARCH · Search PubMed

Results for “virtual screening”

Search indexed PubMed citations on genomics, clinical trials, systematic reviews and public health. Explore titles, authors and supplied subject terms, then open the PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 811 records · Page 45Linked to original sources
PubMed1987

Screening for gestational diabetes: one-hour carbohydrate tolerance test performed by a virtually tasteless polymer of glucose.

Although the 1-hour 50 gm blood glucose screening test is an effective way of detecting diabetes in pregnancy, the taste of available glucose drinks often creates gastrointestinal symptoms and leads to refusal of the patient to be tested. The efficacy of a virtually tasteless glucose polymer in testing carbohydrate tolerance in pregnancy was determined. Sixty-one pregnant patients undergoing screening for gestational diabetes underwent a 1-hour carbohydrate tolerance test of both glucose and a glucose polymer within 3 days of each other. Analysis of the data revealed a high degree of agreement between the results of the 1-hour carbohydrate tolerance test (kappa = 0.62, p less than 0.0001). These data suggest that glucose polymer can be used effectively in screening for gestational diabetes.

Blood Glucose↗
PubMed2003

Screening CT colonography.

CT colonography (Virtual Colonoscopy) was first introduced in 1994 as a novel imaging technique for the detection of colorectal polyps and cancer. It is currently proposed as a new screening tool for colorectal carcinoma that may be more acceptable to patients than current methods. There are a growing number of published studies evaluating all aspects of CT colonography, including technique, imaging displays, interpretation methods, patient acceptance, and lesion detection accuracy. While there are multiple studies that have found excellent CT colonography results for the detection of larger polyps in high risk or symptomatic patient cohorts, there are very few published studies evaluating the performance of CT colonography in asymptomatic screening patients. Although we do not have the results of large, randomized, controlled trials documenting the performance of CT colonography in screening-type patients, this technique is currently employed at some sites as a screening tool for colorectal carcinoma. Thus, CT colonography has become a part of the controversy surrounding total body CT screening. In this article, the current techniques for colonic preparation and distention will be discussed, as well as the optimum CT protocol, and the recommended use of image displays for time-efficient interpretation. The results of the larger and newer studies will be presented, as well as some of the current clinical uses of CT colonography. Issues specific to the use of CT colonography as a screening test will also be discussed.

Colonography, Computed Tomographic↗
PubMed2000

Extraction of pharmacophore information from high-throughput screens.

Two major advances have been made in the computational perception and utilization of pharmacophores in compound libraries, both real and virtual. Firstly, a hierarchical set of filtering calculations has emerged that can be used to efficiently partition a library into a trial set of pharmacophores. This sequential filtering permits large libraries to be efficiently processed, as well as compounds judged as 'hits' to be analyzed in great detail. Secondly, new and extended methods of QSAR (quantitative structure-activity relationship) analysis have evolved to translate pharmacophore information into QSAR models that, in turn, can be used as virtual high-throughput screens for activity profiling of a library.

Combinatorial Chemistry Techniques↗
PubMed1999

Is virtual colonoscopy a cost-effective option to screen for colorectal cancer?

OBJECTIVE: Computed tomography (CT) or magnetic resonance (MR) colonography is a new technique that uses data generated from CT or MR imaging to create two- and three-dimensional scans of the colon. It has been advocated to become the new primary technique of screening for colorectal cancer. The economic feasibility of such recommendation, however, has not yet been evaluated. METHODS: The cost-effectiveness of two screening strategies using CT colonography or conventional colonoscopy was compared by computer models based on a Markov process. We supposed that a hypothetical population of 100,000 subjects aged 50 yr undergoes a screening procedure every 10 yr. Suspicious findings of CT colonography are worked-up by colonoscopy. After polypectomy, colonoscopy is repeated every 3 yr until no adenomatous polyps are found. RESULTS: Under baseline conditions, screening by CT colonography costs $24,586 per life-year saved, compared with $20,930 spent on colonoscopy screening. The incremental cost-effectiveness ratios comparing CT colonography to no screening and colonoscopy to CT colonography were $11,484 and $10,408, respectively. Screening by colonoscopy remains more cost-effective even if the sensitivity and specificity of CT colonography both rise to 100%. For the two screening procedures to become similarly cost-effective, CT colonoscopy needs to be associated with an initial compliance rate 15-20% better or procedural costs 54% less than colonoscopy. CONCLUSIONS: To become cost-effective and be able to compete with colonoscopy in screening for colorectal cancer, CT or MR colonography would need be offered at a very low price or result in compliance rates much better than those associated with colonoscopy.

Adult↗
PubMedDate not supplied

Public cholesterol screening in the previously diagnosed: misuse of resources or beneficial function?

The attendance of individuals with a previous diagnosis of hyperlipidemia at public cholesterol screenings is often criticized as a misuse of such programs. This study explored the post-screening actions of 811 participants in a cholesterol screening program who had previously been diagnosed with cholesterol elevations and whose blood levels at this screening required further medical referral. We also studied the responses of physicians from whom these subjects sought care. Within five months, 559 of 753 participants completing the survey (74.0%) sought medical follow-up. Physicians retested the blood cholesterol levels of 75.0% of these 559; high-risk screenees were more likely to be retested and to be informed that their levels were elevated than moderate-risk subjects (P < .0001). Physicians increased cholesterol-lowering dietary advice for high-risk subjects (P < .0001) and medication prescriptions for both risk groups (P < .0001). Participants seeking medical care after the screening program had better cholesterol-lowering dietary practices and reported increased regimen compliance (moderate-risk: P = .01; high-risk: P < .0001) than those individuals not obtaining medical follow-up. One year after screening, blood cholesterol levels were 4.5% lower (P = .001) in those complying with referral but were virtually unchanged in noncompliers. Screening program confirmation of high blood cholesterol levels combined with referral appeared to have a positive impact on previously diagnosed screenees. We conclude that there may be merit in including previously diagnosed individuals in cholesterol screening programs.

Adult↗
PubMed1986

An anesthesia information system for monitoring and record keeping during surgical anesthesia.

We have developed an anesthesia information system (AIS) that supports the anesthesiologist in monitoring and recording during a surgical operation. In development of the system, emphasis was placed on providing an anesthesiologist-computer interface that can be adapted to typical situations during anesthesia and to individual user behavior. One main feature of this interface is the integration of the input and output of information. The only device for interaction between the anesthesiologist and the AIS is a touch-sensitive, high-resolution color display screen. The anesthesiologist enters information by touching virtual function keys displayed on the screen. A data window displays all data generated over time, such as automatically recorded vital signs, including blood pressure, heart rate, and rectal and esophageal temperatures, and manually entered variables, such as administered drugs, and ventilator settings. The information gathered by the AIS is presented on the cathode ray tube in several pages. A main distributor page gives an overall view of the content of every work page. A one-page record of the anesthesia is automatically plotted on a multicolor digital plotter during the operation. An example of the use of the AIS is presented from a field test of the system during which it was evaluated in the operating room without interfering with the ongoing operation. Medical staff who used the AIS imitated the anesthesiologist's recording and information search behavior but did not have responsibility for the conduct of the anesthetic.

Anesthesia Department, Hospital↗
PubMed2001

Screening for fetal alcohol syndrome in primary schools: a feasibility study.

BACKGROUND: This project was undertaken as a feasibility study to determine the possibility of screening for fetal alcohol syndrome (FAS) in early school-age children for epidemiological and interventional purposes. METHODS: All elementary schools in two counties in Washington State were asked to screen first graders for possible FAS. A child was screen positive if found to be growth deficient, to have certain specific facial abnormalities, or have a known history of substantial alcohol exposure in gestation. All screen-positive children were invited to "special diagnostic clinics" for final diagnosis and treatment planning. RESULTS: In County A, virtually all students were screened. In County B only about 25% of children were screened. This difference was related to the number of schools that agreed to participate in the project and the methods employed by each county to obtain parental permission. In each county, only about one-half of the screen-positive children were seen in the special clinics for diagnostic considerations. Only one of the seven children found to have FAS had been diagnosed previously. The minimal prevalence of FAS in County A was 3.1 in 1,000 students. The minimal prevalence of FAS in County B could not be calculated. The most efficient component in the screening process leading to a diagnosis of FAS was finding the specific facial features of the disorder. The diagnosis of FAS was generally helpful in improving educational planning. CONCLUSIONS: This study demonstrated that population-based FAS screening within a school system may be possible, but participation is dependent on local trust and understanding of the project before its inception within the schools and the community at large.

Child↗
PubMed1996

Bi-directional dideoxy fingerprinting (Bi-ddF): a rapid method for quantitative detection of mutations in genomic regions of 300-600 bp.

There is a great need for rapid screening methods that detect essentially all mutations. Dideoxy fingerprinting (ddF) is a highly sensitive screening method that is performed by electrophoresing one lane of a Sanger dideoxy termination reaction through a nondenaturing gel. Mutations may produce an extra segment or eliminate a segment from the termination products (informative dideoxy component). In addition, mutations can be detected by the altered mobility of one or more termination segments (informative SSCP component). To screen larger segments with virtually 100% sensitivity, bi-directional ddF (Bi-ddF) was developed. Bi-ddF is a 'second generation ddF' in which the dideoxy termination reaction is performed simultaneously with two opposing primers. Bi-ddF has two important advantages over ddF: (i) the dideoxy component can detect 10 of the 12 types of possible single-base substitutions; and (ii) the SSCP component is enhanced because alterations of mobility can be detected in either the downstream or upstream direction. As a result, Bi-ddF can screen larger regions of genomic DNA with virtually 100% sensitivity. Bi-ddF detected 100% of 28 single-base substitutions in a 494 bp segment containing exons B and C of the human factor IX gene and 100% of 42 single-base substitutions and one microdeletion present in a 577 bp region containing exon H. In a blinded analysis in which 39 wildtype samples were randomly mixed with 51 mutant samples, all mutations were detected with no false positives. Bi-ddF requires essentially the same effort as ddF, yet twofold more DNA sequence can be screened reliably per unit effort.

DNA↗
PubMed2004

Distance underestimation in virtual space is sensitive to gender but not activity-passivity or mode of interaction.

Four groups of undergraduates (half of each gender) experienced a movement along a corridor containing three distinctive objects, in a virtual environment (VE) with wide-screen projection. One group simulated walking along the virtual corridor using a proprietary step-exercise device. A second group moved along the corridor in conventional flying mode, depressing a keyboard key to initiate continuous forward motion. Two further groups observed the walking and flying participants, by viewing their progress on the screen. Participants then had to walk along a real equivalent but empty corridor, and indicate the positions of the three objects. All groups underestimated distances in the real corridor, the greatest underestimates occurring for the middle distance object. Males' underestimations were significantly lower than females' at all distances. However, there was no difference between the active participants and passive observers, nor between walking and flying conditions.

Adolescent↗
PubMed2005

Exposure to a rotating virtual environment during treadmill locomotion causes adaptation in heading direction.

The objective of this study was to investigate the adaptive effects of variation in the direction of optic flow, experienced during linear treadmill walking, on modifying locomotor trajectory. Subjects (n=30) walked on a motorized linear treadmill at 4.0 km h(-1) for 24 min while viewing the interior of a 3D virtual scene projected on to a screen 1.5 m in front of them. The virtual scene depicted constant self-motion equivalent to either (1) walking around the perimeter of a room to one's left (Rotating Room group) or (2) walking down the center of a hallway (Infinite Corridor group). The scene was static for the first 4 min and then constant rate self-motion was simulated for the remaining 20 min. Before and after the treadmill locomotion adaptation period subjects performed five stepping trials. In each trial they marched in place to the beat of a metronome at 90 steps min(-1) for a total of 100 steps while blindfolded in a quiet room. The subject's final heading direction (deg) and final X (fore-aft, cm) and final Y (medio-lateral, cm) positions were measured for each trial. During the treadmill locomotion adaptation period subjects' 3D torso position was measured. We found that subjects in the Rotating Room group, as compared with the Infinite Hallway group: (1) showed significantly greater deviation during post-exposure testing in the heading direction and Y position opposite to the direction of optic flow experienced during treadmill walking; and (2) showed a significant monotonically increasing torso yaw angular rotation bias in the direction of optic flow during the treadmill adaptation exposure period. Subjects in both groups showed greater forward translation (in the +X direction) during the post-treadmill stepping task that differed significantly from their pre-exposure performance. Subjects in both groups reported no perceptual deviation in position during the stepping tasks. We infer that viewing simulated rotary self-motion during treadmill locomotion causes adaptive modification of sensorimotor integration in the control of position and trajectory during locomotion, which functionally reflects adaptive changes in the integration of visual, vestibular, and proprioceptive cues. Such an adaptation in the control of position and heading direction during locomotion, because of the congruence of sensory information, demonstrates the potential for adaptive transfer between sensorimotor systems and suggests a common neural site for processing and self-motion perception and concurrent adaptation in motor output.

Adaptation, Physiological↗
PubMed2001

A rapid method to map mutations in Drosophila.

BACKGROUND: Genetic screens in Drosophila have provided a wealth of information about a variety of cellular and developmental processes. It is now possible to screen for mutant phenotypes in virtually any cell at any stage of development by performing clonal screens using the flp/FRT system. The rate-limiting step in the analysis of these mutants is often the identification of the mutated gene, however, because traditional mapping strategies rely mainly on genetic and cytological markers that are not easily linked to the molecular map. RESULTS: Here we describe the development of a single-nucleotide polymorphism (SNP) map for chromosome arm 3R. The map contains 73 polymorphisms between the standard FRT chromosome, and a mapping chromosome that carries several visible markers (rucuca), at an average density of one SNP per 370 kilobases (kb). Using this collection, we show that mutants can be mapped to a 400 kb interval in a single meiotic mapping cross, with only a few hundred SNP detection reactions. Discovery of further SNPs in the region of interest allows the mutation to be mapped with the same recombinants to a region of about 50 kb. CONCLUSION: The combined use of standard visible markers and molecular polymorphisms in a single mapping strategy greatly reduces both the time and cost of mapping mutations, because it requires at least four times fewer SNP detection reactions than a standard approach. The use of this map, or others developed along the same lines, will greatly facilitate the identification of the molecular lesions in mutants from clonal screens.

Animals↗
PubMed2002

Does virtual colonoscopy have a major role in population-based screening?

In summary, technical advances in the performance of VC are occurring at a very rapid pace. These technical improvements will undoubtedly improve the polyp detection rate and reduce false-positive and false-negative examinations. The concept of VC is clearly attractive and the general public is enamored with everything that has an association with virtual reality. As other articles in this issue have revealed, there are many techniques in development to help stratify patients at risk for colon cancer. As we begin to focus our health care resources on those at highest risk, the less need there is for inexpensive, broadly based screening techniques. Clearly, those patients at high risk for having polyps are better served by colonoscopy because of its therapeutic potential. That being said, in the view of this author, if a virtual preparation can be achieved and the cost of VC can be kept relatively low, then this technique will become part of our mainstream clinical practice. If an immaculate colon preparation must be performed and if the costs reflect standard abdominal and pelvic CT rather than a special reduced cost for VC, then it is doubtful that there will be any significant impact from this technology

Colonic Polyps↗
PubMed1989

Cervical cytological services in the Orange Free State. Demographic characteristics.

In the Bloemfontein academic hospitals the incidence of infiltrating cervical cancer is four times that of severe cervical intra-epithelial neoplasia (CIN III). A cross-sectional survey was therefore conducted to identify the extent of cervical cytological services in the Orange Free State. From the four major laboratories dealing with the population of the OFS all cytological reports of one randomly chosen working day per month in 1985 were analysed for three demographic variables: age, race, and locality according to census district. As a control, similar demographic variables were identified from national census figures for 1980, limited to females aged 15-65 years. The follow-up of patients with CIN III diagnosed cytologically in the academic hospitals in Bloemfontein was determined. Results showed significant differences (P less than 0.001) in age, race and locality between the census population and that submitted to cytological screening. Acceptable figures were virtually limited to Bloemfontein, predominantly in white patients, while three-quarters of the population of the OFS is black. The peak frequency in the age distribution in the screened population was 25-35 years and 15-24 years for the census population. Follow-up for patients with CIN III was 65.5%. The conclusion is that the female population of the OFS is not representatively reached by existing cytological services.

Adolescent↗
PubMed2003

Optical 3D surface digitizing in forensic medicine: 3D documentation of skin and bone injuries.

Photography process reduces a three-dimensional (3D) wound to a two-dimensional level. If there is a need for a high-resolution 3D dataset of an object, it needs to be three-dimensionally scanned. No-contact optical 3D digitizing surface scanners can be used as a powerful tool for wound and injury-causing instrument analysis in trauma cases. The 3D skin wound and a bone injury documentation using the optical scanner Advanced TOpometric Sensor (ATOS II, GOM International, Switzerland) will be demonstrated using two illustrative cases. Using this 3D optical digitizing method the wounds (the virtual 3D computer model of the skin and the bone injuries) and the virtual 3D model of the injury-causing tool are graphically documented in 3D in real-life size and shape and can be rotated in the CAD program on the computer screen. In addition, the virtual 3D models of the bone injuries and tool can now be compared in a 3D CAD program against one another in virtual space, to see if there are matching areas. Further steps in forensic medicine will be a full 3D surface documentation of the human body and all the forensic relevant injuries using optical 3D scanners.

Computer Peripherals↗
PubMedDate not supplied

Analysis of irradiated lung and heart volumes using virtual simulation in postoperative treatment of stage I breast carcinoma.

AIMS AND BACKGROUND: The aim of the study was to assess the usefulness of virtual simulation in postoperative radiotherapy treatment planning of early-stage breast cancer and to evaluate its potential to reduce the volume of critical structures exposed compared to treatment plans produced by a conventional 2D system. METHODS AND STUDY DESIGN: Eighteen patients undergoing breast radiotherapy following conservative surgery for small breast carcinomas were studied. Scans from spiral CT equipment (with the patient in the treatment position) were transferred to a virtual simulator. From the screen images the operator contoured breast, lung and heart. Calculations were made of the extent to which the heart and lung were included in the irradiation fields (50% isodose line of tangential fields). RESULTS: Manual contouring was time-consuming, but when virtual simulation was used, the mean volume of the lung included in the radiation fields was significantly reduced compared to the 2D treatment plan (4.5% vs 5.4%, P = 0.034); in addition, a slight reduction was observed for the heart (0.5% to 1.2%), but this was not statistically significant. CONCLUSIONS: With a 3D system we obtained optimal target coverage and a reduction of the dose to critical structures (statistically significant only for the lung). From a clinical point of view, this 0.9% reduction in the mean irradiated lung volume is probably not significant, as the percentage irradiated with a 2D system is considerably below the recommended value. Furthermore, our analysis was performed in a relatively small group of patients; for a reliable estimate larger series would be required. Consequently, the 3D system should not be considered in routine treatment after breast conserving surgery for early stage carcinomas; for the time being it should be reserved for selected cases.

Adult↗
PubMed2001

Validation of virtual colonoscopy in the detection of colorectal polyps and masses: rationale for proper study design.

BACKGROUND: Colorectal cancer, the second-leading cause of cancer-related mortality, is a preventable malignancy in many cases. Despite the availability of several screening modalities, compliance with screening recommendations remains unacceptably low. Virtual colonoscopy is a novel, minimally-invasive technique with the potential to increase colorectal cancer screening rates, but its effectiveness must first be validated. Published studies comparing virtual colonoscopy to conventional colonoscopy have reported varying results. These discrepancies may be attributed to differences in bowel preparation and scanning techniques, as well as errors in endoscopic lesion measurement, endoscopic colonic segmental localization, and the ability of conventional colonoscopy to actually detect lesions. These methodological issues can affect scientific results and ultimately affect the public's perception of this emerging technique. AIM: The goal of this report is to expose existing methodological shortcomings and propose solutions incorporated in this study design. This article describes the rationale, study design, and outcome definitions of a single-center, blinded, direct comparative trial aiming at assessing the ability of virtual colonoscopy to detect colorectal polyps and masses relative to the criterion standard, conventional colonoscopy. DESIGN FEATURES: Bowel preparation was standardized using oral sodium phosphate lavage, orally administered iodinated contrast, and controlled colonic insufflation. Segmental unblinding allowed a second-look when results were discrepant and polyp matching was performed using an algorithm based on segmental localization and lesion size determination. CONCLUSIONS: This methodology could be applied to other studies assessing the accuracy of virtual colonoscopy in order to have uniformity of results.

Colonic Polyps↗
PubMed1984

The Haller's organ roof and anterior pit setae of Argas ticks (Ixodoidea: Argasidae). Subgenera Secretargas and Ogadenus.

Adults of the Argas subgenera Secretargas (3 species) and Ogadenus (1 species) were studied by scanning electron microscopy. In each species, the anterior pit and Haller's organ are situated in a large dorsal hump of Tarsus I and the 9 setae of the anterior pit are characteristic of the genus Argas in structure and numbers. In A. (S.) transgariepinus, an Ethiopian-Palearctic crevice-dwelling parasite of bats, the Haller's organ capsule roof is solid with a slitlike transverse aperture. In A. (S.) hoogstraali and A. (S.) echinops, Malagasy soil-dwelling parasites of Oplurus (Varanidae) lizards and the hedgehog-tenrec (Insectivora: Tenrecidae), respectively, the Haller's organ is virtually unroofed but partially screened by arborescent dorsal projections from the posterior wall of the capsule, and the open capsule contains numerous fine pleomorphs. In A. (O.) brumpti, a soil-dwelling parasite of the hyrax (Procavia), other terrestrial mammals, and lizards in the Ethiopian Region, the capsule is also virtually unroofed and contains numerous fine pleomorphs. The unroofed capsule is probably phylogenetically primitive and occurs only in these 3 and 2 other Argas species. The soil microhabitat (in Argas confined to 3 of the 4 species recorded here), and the reptile or ancient mammal hosts of these 3 species, as well as the zoogeographical isolation of 2 of the species in the Malagasy Region, are distinctive in this genus of 56 species. The interrelationships between an unroofed Haller's organ capsule and unusual biological properties remain to be determined.

Animals↗