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At least 1,423 records · Page 79Linked to original sources
PubMed2000

Design and development of computer-aided chemical systems: representation and balance of inorganic chemical reactions

A model for the tracking of inorganic chemical reactions is proposed. Designed to acquire, process, and solve a great number of inorganic reactions, this model will hopefully contribute to the development of powerful computer-aided chemistry teaching systems for use within or without the environment of a virtual laboratory. Using full representation of an inorganic reaction to allow the extraction of chemical knowledge, incomplete reactions (where species are absent) may be completed by adding the necessary species, and reactions may be solved and balanced. Various types of reaction are classified, and a layer-based model is defined for the solution of different reaction types, establishing the basis for the construction of a system which, based on a wide set of production rules, is capable of solving an incomplete inorganic chemical reaction.

Journal Article↗
PubMed1995

A new method for studying plaque morphology.

A histologic method was developed for three-dimensional (3-D) analysis of atherosclerotic plaques removed from the carotid bifurcation during endarterectomy. By sectioning the plaque at frequent intervals (0.5 to 1.0 mm), it is possible to obtain important information on plaque constituents with regard to their volume and distribution within the lesion. These data from each section are combined with those from other sections and displayed in a 3-D format for the entire length of the lesion. The tissues making up each of the 10 carotid plaques were outlined and digitized for each histologic section by position along the lesion. From the areas outlined a 3-D model was created by a computer-aided design program. Quantitative information on tissue distribution within the plaque was measured. Fibrous tissue constituted between 35% and 70% of plaque volume; loose necrosis from 0.5% to 30% of the plaque and thrombus occupied, at a maximum, 10% even though if was present in six of the 10 plaques. To investigate the distribution of constituents about the long axis, measurements were also made from each of the four quadrants of each section. The reproducibility of the measurements of three sets of sections at 10-mm separation showed that estimates of the amount of some constituents were very reproducible whereas others had considerable variation related to the small volume they occupied within the lesion. By generating a complete 3-D reproduction of the contents of atherosclerotic plaques, it may be possible to identify those features of the plaque that are most responsible for the development of ischemic events.

Arteriosclerosis↗
PubMed2003

Use of stereolithography to manufacture critical-sized 3D biodegradable scaffolds for bone ingrowth.

A novel approach to the manufacture of biodegradable polymeric scaffolds for tissue-engineering utilizing stereolithography (SLA) is presented. SLA is a three-dimensional (3D) printing method that uses an ultraviolet laser to photo-crosslink a liquid polymer substrate. The current generation of SLA devices provide a 3D printing resolution of 0.1 mm. The experiments utilized a biodegradable resin mixture of diethyl fumarate (DEF), poly(propylene fumarate) (PPF), and a photoinitiator, bisacylphosphine oxide (BAPO). The PPF is crosslinked with the use of the SLA's UV laser (325-nm wavelength). An SLA device was retrofitted with a custom fixture build tank enclosing an elevator-driven build table. A 3D prototype model testing the manufacturing control this device provides was created in a computer-aided-design package. The resulting geometric data were used to drive the SLA process, and a DEF/PPF prototype part was successfully manufactured. These scaffolds have application in the tissue engineering of bony substrates.

Biocompatible Materials↗
PubMed2002

Fragment analysis in small molecule discovery.

Cheminformatics is playing an ever-increasing role in small molecule drug discovery. The widespread use of high-throughput screening (HTS) and combinatorial chemistry techniques has led to the generation of large amounts of pharmacological data which, in turn, has catalyzed the development of computational methods designed to reduce the time and cost in identifying molecules suitable for pharmaceutical development. This review focuses on recent advances in the field of substructure analysis, an increasingly popular data mining technique with applications at many levels of the discovery process, including HTS, compound library design, virtual screening and the prediction of biological activity.

Animals↗
PubMed1989

A computer aid for choosing HMOs: design of a new interface.

This paper reports on a new interface design. The presentation is similar to a newspaper style, allowing a familiar format and advertisement. In addition, the design includes steps to ease data collection, features to help users influence others in the organization, and a dynamic allocation of menu lists that reflect user's knowledge and previous interest.

Decision Making, Computer-Assisted↗
PubMed2005

[Surgical management of craniomaxillofacial fibrous dysplasia].

OBJECTIVE: To explore the method to obtain good aesthetic and functional results in surgical management of craniomaxillofacial fibrous dysplasia and correct the grotesque deformity. METHODS: According to the type of the lesions, different excision and reconstruction methods were used. RESULTS: 19 cases (4 monostotic cases and 15 polyostotic cases) were surgically treated. The period of follow-up range from 9 months to 5 years, all patients obtained satisfactory aesthetic and functional results. No relapse happened during follow up. CONCLUSIONS: Based on modern craniomaxillofacial techniques and computer aided design, extensive radical excision and craniomaxillofacial skeleton reconstruction could be safely accomplished, and the better results were obtained, both aestheticly and functionally.

Adolescent↗
PubMed2000

The application of computer aided product development techniques in medical modelling topic: rehabilitation and prostheses.

When considering reconstructive surgery it is often difficult to ascertain the exact nature of affected internal anatomy. Although advances in Computed Tomography (CT) and Magnetic Resonance Imaging (MRI) have enabled the generation of 3D reconstructions of internal anatomy, they are often only available as fixed 2D images. These may obscure important details or prove ambiguous depending upon the angle of view. Another problem is maintaining accuracy of reconstruction that may involve osteotomy, tissue grafts or implants. In such circumstances the ability to plan and rehearse complex procedures can prove invaluable, greatly improving surgical results whilst helping to eliminate potential errors and reducing theatre time. In this context 3D scan data can be treated as the equivalent of Computer Aided Design (CAD) data and can be applied to the production of accurate physical models. The approach undertaken by the DERC is based on close collaboration with surgical departments and enables the rapid and economic production of medical models based on CT/MRI data. This paper illustrates the transfer of product design technologies into a clinical context. Specifically, the use of 3D surface scanning and rapid prototyping technologies as an aid to post operative reconstruction is described. An evaluation of the application of product development tools within a clinical context is presented. The paper concludes with an assessment of likely future application in this area.

Computer-Aided Design↗
PubMed2002

Restorative material options for CAD/CAM restorations.

Advances in adhesive dentistry and technological developments using dental computer-aided design (CAD)/computer-aided manufacturing (CAM) systems have provided alternative esthetic restorations to conventional laboratory processed restorations. Restorative materials for CAD/CAM-generated restorations must be able to withstand the rigors of the milling process, while providing clinical longevity once cemented. The esthetic restorative materials currently available for use with the Cerec System provide dentists with ceramic and polymer options for inlays, onlays, veneers, and crowns.

Ceramics↗
PubMed2006

Design and evaluation of a computer reminder system to improve prescribing behaviour of GPs.

OBJECTIVE: To evaluate the implementation of a decision support system with reactive computer reminders to improve drug prescribing behaviour. METHODS: A clustered RCT with an incomplete block design was carried out in the south of the Netherlands: 25 GPs received reminders on antibiotics and asthma/COPD prescriptions, 28 GPs received reminders on cholesterol prescriptions. Prescribing guidelines were integrated into the GP information system, which was installed in the GPs practices of the intervention group. When the computer program was in use, a reminder popped up if the GP deviated from the guidelines during prescribing. PRIMARY OUTCOME: prescription according to the guidelines as a percentage of total prescriptions of a specific drug. Furthermore, an evaluation on the user-friendliness of the CRS in the GP's practice was carried out through questionnaires and interviews. RESULTS: Presently analyses are being carried out. Preliminary results indicate that the CRS study supported our expectations. In general, there seems to be a reduction in the numbers of prescriptions according to the advices of the computerised guidelines not to prescribe certain drugs. Final analysis will be performed shortly. In general, the Computer Reminder System was perceived as stable and user friendly. CONCLUSION: We created a stable and user friendly Computer Reminder System which was adjusted to the needs and demands of GPs. Preliminary results regarding the effectiveness of the system seem to indicate that the implementation of a Computer Reminder System with reactive reminders improves drug prescribing behaviour.

Drug Prescriptions↗
PubMed1992

Retinal cartography. An analysis of two-dimensional and three-dimensional mapping of the retina.

The current two-dimensional (2D) retinal drawing chart is an azimuth equidistant representation of the retina. The distortion produced by this chart was analyzed and compared to other 2D projections, such as stereographic, equal area, and orthographic maps of the retina. Circumferential distortion was calculated for lesions at varying distances from the macula using the azimuth equidistant retinal map and was found to increase exponentially as a function of the distance from the macula. Circumferential distortion was 57.1% at the equator, 88.5% 3 mm anterior to the equator, and 137.8% 6 mm anterior to the equator. A three-dimensional (3D) model of the retinal surface was created using 3D computer assisted design (CAD) software. This 3D model was able to represent retinal lesions such that their true size, shape, location, and orientation were all conserved. Retinal lesions could be viewed from multiple angles and examined in cross section. The use of 3D CAD software coupled with ultrasound or magnetic resonance imaging data has the potential to represent retinal lesions more accurately than current methods.

Choroid Neoplasms↗
PubMed1986

A generic computer program for systematic desensitization: description, construction and case study.

A computer program designed to provide systematic desensitization for phobias is described. Clients are taught by computer-aided instruction to develop their own personalized phobic hierarchy which is then used by the computer as the phobic stimulus in desensitization proper. The results of a pilot trial with an agoraphobic client indicate that the computer program was successful.

Adult↗
PubMed1997

A hierarchical system for the coding of dental information in reports and computer-assisted identifications.

Dental coding systems have hitherto been developed mainly to record treatment. The present hierarchical system was specially designed for computer aided dental identification and has been tested for 15 years in the Norwegian register of missing persons. It is in addition well suited for rapid and exact reporting of dental findings in identification cases. The system has also been proposed for adoption by Interpol.

DMF Index↗
PubMed2003

A new model-based RSA method validated using CAD models and models from reversed engineering.

Roentgen stereophotogrammetric analysis (RSA) was developed to measure micromotion of an orthopaedic implant with respect to its surrounding bone. A disadvantage of conventional RSA is that it requires the implant to be marked with tantalum beads. This disadvantage can potentially be resolved with model-based RSA, whereby a 3D model of the implant is used for matching with the actual images and the assessment of position and rotation of the implant. In this study, a model-based RSA algorithm is presented and validated in phantom experiments. To investigate the influence of the accuracy of the implant models that were used for model-based RSA, we studied both computer aided design (CAD) models as well as models obtained by means of reversed engineering (RE) of the actual implant. The results demonstrate that the RE models provide more accurate results than the CAD models. If these RE models are derived from the very same implant, it is possible to achieve a maximum standard deviation of the error in the migration calculation of 0.06 mm for translations in x- and y-direction and 0.14 mm for the out of plane z-direction, respectively. For rotations about the y-axis, the standard deviation was about 0.1 degrees and for rotations about the x- and z-axis 0.05 degrees. Studies with clinical RSA-radiographs must prove that these results can also be reached in a clinical setting, making model-based RSA a possible alternative for marker-based RSA.

Algorithms↗
PubMed2000

Application of secondary structure prediction in antisense drug design targeting protein kinase C-alpha mRNA and QSAR analysis.

AIM: To optimize the design of antisense drug targeting protein kinase C-alpha (PKC-alpha) mRNA and obtain better antisense drugs than ISIS3521 that is undergoing clinical trials. METHODS: RNAstructure (version 3.21, 1999) was utilized to predict the optimal and suboptimal secondary structures of human PKC alpha mRNA (GenBank, X52479), and 29 antisense phosphorothioate oligodeoxynucleotides (S-ODN) targeting the secondary structural elements, 3 partly matched S-ODN and 1 scrambled 3521 were designed. ISIS3521 was set as positive control. Mean (n = 3-5) 50% inhibitory effects on proliferation of A549 cells (IC50) of S-ODN were evaluated. Free energies (delta G degree 37) relating to the target secondary structural elements were calculated according to the nearest neighbor model. The quantitative structure-activity relationship (QSAR) analysis through multiple regression was obtained by SPSS. RESULTS: Three S-ODN; (5'-AGCCCA-GCCGCTTGGCTGGG-3', 5'-AGGAGTGCAGCTGC-GTCAAG-3', 5'-TCAGAGGG-ACTGATGACTTT-3') had lower IC50[(48 +/- 7), (50 +/- 4), (64 +/- 2.7) nmol.L-1, respectively] than that of ISIS3521 [(81 +/- 25) nmol.L-1]. The number of bases comprising the target secondary structural element bulge loop, internal loop, and knot, the free energy of S-ODN (delta G degree 37S), and reaction (delta G degree 37R) were important parameters in QSAR equation. In the multiple regression, R was 0.68, P = 0.0193. Not tally with the equation, two S-ODN (5'-TCAAATGGAGG-CTGCCCGGC-3', 5'-AAAACGTCAGCCATGGTCCC-3') with favorable target structures and delta G degree 37 did not behave good activities. CONCLUSION: Computer aided design was helpful to obtain S-ODN with better in vitro effect than current positive drug. The degree of instability of secondary structural elements and delta G degree 37 were important factors for drug activity. Other important factors needed for further investigation.

Antineoplastic Agents↗
PubMedDate not supplied

Fabrication of a jellyfish valve for use in an artificial heart.

For a valve to be fabricated seamlessly into an artificial heart (AH) blood pump, a jellyfish valve has been developed, in which a thin membrane is fixed at the center of a valve seat having several spokes to protect against prolapse of the membrane. The valve is superior in performances to a Björk-Shiley valve, and reveals good blood compatibility. The valve would be very useful not only for AH animal study, but for future clinical use in infants to adults. Several institutions are already trying the valve. In this paper, the fabrication of the jellyfish valve is introduced, and in vitro and in vivo results summarized. A computer aided design (CAD) system was developed to cut a male wax mold of the valve seat. The input parameters to the CAD are diameter, height, thickness of rim, number of spokes, width and thickness of spokes, etc. Jellyfish valves with diameters of 4 to 27 mm have already been fabricated for many types of AHs and assist pumps.

Animals↗
PubMed1995

Tradeoffs between motion and stability in posterior substituting knee arthroplasty design.

The purpose of this study was to examine how changes in component geometry of posterior substituting knees affect tibiofemoral kinematics and prosthesis stability. Most posterior cruciate ligament substituting prostheses rely on an articulation between a femoral cam and tibial spine to provide anterior-posterior stability of the knee. Failure of this ligament substitution mechanism has resulted in knee dislocations with several different posterior substituting designs. A computer model of a generic posterior substituting prosthesis was altered to analyze the effects of five design parameters (tibial spine height, spine anterior-posterior position, femoral component posterior radius, and femoral cam anterior-posterior and distal-proximal position) on prosthesis stability, tibiofemoral kinematics, and maximum obtainable knee flexion. Prosthesis stability was characterized by a 'dislocation safety factor', defined as the vertical distance from the bottom of the femoral cam to the top of the tibial spine. Computer simulations revealed that posterior substituting knees are most likely to dislocate at maximum knee flexion. Prosthesis stability can be improved by increasing the tibial spine height and moving the femoral cam posteriorly. Our results suggest there is a tradeoff between maximum knee flexion and prosthesis stability. We found that relatively small gains in maximum knee flexion, made through design changes, may cause substantial decreases in prosthesis stability.

Arthrography↗
PubMed1995

A CAD/CAM system for the production of metal copings for porcelain-fused-to-metal restorations.

A computer-aided design and manufacture system for the production of metal copings for porcelain-fused-to-metal restorations is described and evaluated. The three stages of production: digitizing, mathematical processing, and milling are described, with emphasis on the system's ability to produce metal copings for both single-unit and multiple-unit restorations. Evaluation of the marginal fit of the produced copings demonstrates the potential for clinically acceptable results.

Analog-Digital Conversion↗