Search PubMed⌕ Search

SEARCH · Search PubMed

Results for “computational design”

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 901 records · Page 50Linked to original sources
PubMed1998

Enhancing the flexibility and adaptability of the DARC structural representation for computer-aided drug design.

Noticeable progress has been achieved in the determination of dynamic topochromatic variables for the structural representation of compounds and their situation in a given population. These independent structural variables can be further combined into more complex variables. Their contributions to the evolution of an associated property can therefore be evaluated with certainty. The risk of having correlated variables is avoided while the structural description remains exhaustive. In order to enhance the interpretative ability of the QSAR model, one or several physicochemical properties can be taken with these structural parameters as explanatory variables. Typically, partition coefficients, 3-D and quantum mechanical data are used for this purpose. The structural aspects not taken into account by the physicochemical parameters are reflected in the remaining topochromatic variables. The use of these new concepts is presented in a study of carbazole mutagenicity. The model explains 99% of the total variance with one external property and four additional topochromatic variables. The modulation of the heat of formation of an intermediate by two topochromatic variables suggests a much more precise interpretation than a simple combination of the usual external variables.

Animals↗
PubMed2005

[Cascade reactions of unsaturated xanthates and related reactions: computer-assisted molecular design and analysis of reaction mechanisms].

Chugaev reaction provides access to olefins from alcohols without rearrangement through pyrolysis of O-alkyl S-alkyl dithiocarbonates (xanthates) via cis elimination. Xanthates having no beta-hydrogens undergo thione-to-thiol rearrangement to give S,S-dialkyl dithiocarbonates (thiolcarbonates). Based on these backgrounds, we intended to use the dithiolcarbonates as precursors of thiols. Xanthates could be converted to the corresponding dithiolcarbonates by Lewis-acid catalysis. Pyridine N-oxides and 4-dimethylaminopyridine also catalyzed the rearrangement reaction. On the other hand, O-(2-alkenyl) S-alkyl dithiocarbonates undergo [3,3]-sigmatropic rearrangement to give the allylically rearranged S-(2-alkenyl) S-alkyl dithiocarbonates. The homoallylic xanthates gave the corresponding dithiolcarbonates on heating with phenols. Pyrolysis of allylic dithiolcarbonates caused retro-ene type reaction to give the allylic sulfides in which allylic rearrangement also occurs. Coupling of these pericyclic reactions with intramolecular Diels-Alder reaction affords a one-pot synthetic method for the construction of hydroisobenzothiophenes. The mechanisms of the cascade and related reactions are demonstrated by location of the transition states using molecular orbital calculation method at various levels of theory involving density functional theory (DFT).

Chemistry, Organic↗
PubMedDate not supplied

Computer aids in drug design--highlights.

An outline of some procedures used for computer aided drug design has been given. The emphasis is on lead generation, both primary and secondary, and on current lead optimization processes which rely on an appreciation of ligand-receptor interactions. The areas covered include techniques for structure based drug design and lead optimization, ligand-receptor interaction studies using molecular surfaces and docking, extraction of pharmacophore pattern to obtain new leads, expert system application etc.

Computer-Aided Design↗
PubMed2004

Towards a MIP-based alignment and docking in computer-aided drug design.

Structural alignment of ligands in their biological conformation is a crucial step in the building of pharmacophoric models in structure-based drug design. In addition, docking algorithms are limited in some cases by the quality of the scoring functions and the limited flexibility of the environment that the different programs allow. On the other hand, GRID molecular interaction potentials (MIPs) have been used for a long time in 3D-QSAR studies. However, in most of these studies the alignment of the molecules is performed on the basis of geometrical or physico-chemical criteria that differ from the MIPs used in the partial least squares statistical analysis. We have previously developed a method to use the same scoring function for the molecular alignment and for 3D-QSAR studies. This methodology, based on the use of GRID potentials, consists in the weighted averaging of similarities of the relevant MIPs of the molecules to be aligned. Here we present a method to obtain the weights for the different GRID probes in the average based on the structural information on protein-ligand complexes for relevant systems. The method, implemented in MIPSIM, is shown to yield good accuracy in the prediction of the alignments for two systems: a set of three inhibitors of dihydrofolate reductase and a set of fifteen non-nucleoside HIV-1 reverse transcriptase inhibitors (NNRTIs). The smooth GRID potentials are shown to capture the flexible character of the active site, as opposed to traditional docking scoring energy functions.

Binding Sites↗
PubMed1997

From serendipity to design: the evolution of drug development in oncology.

Although screening of natural products remains the major method of discovering new anticancer drugs, newer techniques of rational drug design, computer-aided drug design, and combinatorial synthesis promise to broaden the scope of compounds available for screening. Recent changes in Food and Drug Administration rules allow for accelerated approval of drugs for treating cancer and other life-threatening illnesses, although the three-phase process of clinical trials remains largely unchanged.

Antineoplastic Agents↗
PubMedDate not supplied

Lessons from a randomized controlled trial designed to evaluate computer decision support software to improve the management of asthma.

PRIMARY OBJECTIVE: To investigate whether computer decision support software used in the management of patients with asthma improves clinical outcomes. RESEARCH DESIGN: Randomized controlled trial with practices each reporting on 30 patients with asthma over a 6 month period. METHODS AND PROCEDURES: 447 patients were randomly selected from practice asthma registers managed by 17 general practices from throughout the UK. Intervention practices used the software during consultations with these patients throughout the study while control practices did not. MAIN OUTCOMES AND RESULTS: Practice consultations, acute exacerbations of asthma, hospital contacts, symptoms on assessment and medication use. A smaller proportion of patients within the intervention group initiated practice consultations for their asthma: 34 (22%) vs 111 (34%), odds ratio (OR) = 0.59, 95% confidence interval (CI) (0.37-0.95); and suffered acute asthma exacerbations: 12 (8%) vs 57 (17%), OR = 0.43, 95% CI = 0.21-0.85 six months after the introduction of the computer decision support software. There were no discernable differences in reported symptoms, maintenance prescribing or use of hospital services between the two groups. CONCLUSION: The use of computer decision support software that implements guidelines during patient consultations may improve clinical outcomes for patients with asthma.

Asthma↗
PubMed1998

Finite element modelling of a residual lower-limb in a prosthetic socket: a survey of the development in the first decade.

A review is presented of the existing finite element models developed from 1987 to 1996 for the biomechanics of lower-limb prostheses. Finite element analysis can be a useful tool in investigating the mechanical interaction between the residual limb and its prosthetic socket, and in computer-aided design and computer-aided manufacturing of prosthetic sockets. Various assumptions and simplifications are made in these models to simplify the actual problem with complex geometry, material properties, boundary and interfacial conditions, as well as loading situations. The analyses can provide the information on the stress distribution at the stump/socket interface and within the residual limb tissues. More recently, nonlinear models have been developed taking into consideration the process of socket rectifications, the slip/friction conditions and material large deformation. The models so far developed have provided some basic understanding of the biomechanics. Comparison of the predictions of these models with experimental measurements indicated that the predicted stresses were within the ranges measured, although one-to-one correspondence was difficult to achieve. Further research is still required in order to improve these models to obtain higher precision in the results taking into account nonlinear and dynamic effects.

Artificial Limbs↗
PubMed2006

Individual CAD/CAM fabricated glass-bioceramic implants in reconstructive surgery of the bony orbital floor.

BACKGROUND: The aim of the study was to present a set of preliminary cases from an ongoing program of reconstructive procedures using a new technique in the treatment of severe enophthalmos and diplopia after the primary treatment of orbital floor fractures had rendered insufficient results. METHODS: Glass-bioceramic implants were shaped from computed tomography coordinates with computer-assisted design and computer-assisted manufacturing. In this prefabrication process, the implants were milled individually out of a solid block of Bioverit II (3di Gmbh, Jena, Germany). The adequacy of this reconstruction for treating malfunction and aesthetic deficits was evaluated. RESULTS: Eight patients with orbital floor fractures underwent successful surgery. The results were encouraging, with all patients showing a good functional and aesthetic outcome. CONCLUSIONS: Computer-assisted design/computer-assisted manufacturing implants made of Bioverit II can be used for a very accurate and successful secondary reconstruction of the orbital floor. However, it addresses only a few aspects of the treatment of orbital floor fractures and should be considered as an equal alternative to other reconstruction methods.

Adult↗
PubMedDate not supplied

Financial considerations regarding acquisition of the Siemens Cerec computer reconstruction system.

There has been much interest in the in-office fabrication of ceramic posterior restorations using computer-aided design and computer-aided manufacture (CAD-CAM) units. One concern that practitioners have concerning the use of one of these systems is the initial expense of the CAD-CAM unit for the office. This article deals with the financial implications involved when considering the purchase or lease of a CEREC (CAD-CAM) unit.

Capital Financing↗
PubMed2001

Anterior esthetic rehabilitation on teeth and dental implants optimized with Procera technology: a case report.

With the latest developments of the Procera system, all-ceramic crowns have become an attractive solution to provide functional and esthetic rehabilitation on teeth and dental implants. The Procera AllCeram crown and Procera Abutment embrace the concept of computer-assisted design and computer-assisted machining (CAD/CAM) and can be used together for optimal esthetic result. The purpose of this case report was to illustrate the advantages of these new components for complex anterior rehabilitation. Three natural teeth and a Procera Abutment were restored using four Procera AllCeram crowns. Treatment planning and esthetic benefits are discussed.

Aluminum Oxide↗
PubMed2005

Machining accuracy of CAD/CAM ceramic crowns fabricated with repeated machining using the same diamond bur.

The purpose of this study was to investigate the effect of repeated machining up to 51 times using the same diamond bur on machining accuracy of inner and outer surfaces of CAD/CAM (computer-aided designing and computer-aided manufacturing) machined ceramic crowns. The surface topography of machined crowns was examined using photographs. It was found that machining accuracy was not affected by the number of machining times. In all measuring points, the inner surface was machined to a dimension larger than the die model (i.e., increased gap), whereas the outer surface was machined to a dimension smaller than the crown model (i.e., smaller crown). Photo observation showed that cervical contour was machined in a clear, rounded form from 1st to 11th crowns.

Analysis of Variance↗
PubMed1999

A 3-year study of inlays milled from machinable ceramic blocks representing 2 different inlay systems.

OBJECTIVE: The aim of this study was to evaluate the clinical performance of ceramic inlays made from machinable ceramic blocks. METHOD AND MATERIALS: The 2 inlay systems involved computer-aided design and computer-aided machining (Cerec Cos 2.1) or copy-milling technique (Celay). The study comprised 15 Celay inlays and 15 Cerec inlays placed in 17 patients. The inlays were evaluated clinically at baseline (1 week) as well as 1 and 3 years later (modified California Dental Association quality evaluation system). RESULTS: One Celay inlay fractured after 1 year of service, and 2 Cerec inlays were replaced, 1 after 6 months and 1 after 1 year, because of pulpal pain and persisting hypersensitivity. One Celay inlay lost retention after 2 years. At the 3-year evaluation, chipping and hairline cracks were seen in 2 Celay inlays. Progressive disintegration of the marginal luting cement was seen for both Celay and Cerec inlays. The remaining 25 inlays performed satisfactorily throughout the 3-year period. CONCLUSION: Because of their relatively high failure rate, these inlays should be reserved for esthetic indications.

Cementation↗
PubMed1992

Dental caries in the future: a global view.

Although the prevalence of caries has decreased markedly in children, adolescents, and young adults in most industrialized countries, caries continues to be the main reason for tooth loss, particularly among the high risk segment of the population. In many developing countries, where traditional dietary patterns have changed to include sugar-containing foods and beverages, caries prevalence has increased and will continue to do so in the immediate future. Accordingly, it would be a serious mistake to be complacent about caries prevention. In future industrialized countries will see computers playing a significant role in cariology, finding applications not only in research and practice administration but directly in clinical practice as well. They will be used in every operatory in the assessment of caries risk, the recording of caries prevalence, the direct storing of radiographic information, and the restoration of carious teeth, assisted by computer-aided design and computer-aided manufacture (CAD/CAM) technology. Fluoride therapy, both systemic and topical, will continue to be the basis of caries prevention. Dental sealants, which are highly effective in protecting pits and fissures when applied soon after the teeth erupt, will be more widely used in the future when insurance plans will pay for prevention. Substitution of sucrose and syrups by non-fermentable sweetening agents can also reduce caries increments, but most agents are more expensive than sucrose and require consumer education to pay for the additional cost. Caries, as an infectious and transmissible disease, is amenable to prevention by interfering with the chain of transmission or by suppressing the putative pathogens, the mutans streptococci, in infected patients.(ABSTRACT TRUNCATED AT 250 WORDS)

Analysis of Variance↗
PubMed1995

A new computer-assisted method for fabrication of crowns and fixed partial dentures.

The availability of high-technology systems that use computer-aided design and computer-aided machining is on the increase. One such system is the Procera system, which is currently providing cost-effective, high-quality dental restorative services to dental laboratories and to dentists. A reduction in cost to the dentist, and ultimately to the patient, is a major advantage of the Procera system. Cost benefits combined with its continued success in producing crowns and fixed partial dentures that meet professional standards of care should enhance the acceptance of this new technology.

Computer-Aided Design↗
PubMed1998

Procera: a new way to achieve an all-ceramic crown.

The Procera System embraces the concept of computer-assisted design and computer-assisted machining to fabricate an all-ceramic crown composed of a densely sintered, high-purity aluminum oxide coping combined with a compatible veneering porcelain. Strength, precision of fit, color stability, cementation, and wear characteristics are among the many factors that concern clinicians when fabricating all-ceramic restorations with this new crown system. This article presents, in summary form, the data from the many studies on Procera AllCeram crowns that have been conducted at clinical and laboratory centers around the world. The evidence reported in these studies clearly demonstrates that the Procera AllCeram crown represents a combination of computer technology and creativity for which a positive prognosis can be made. Today its application is restricted to single crowns; however, with continued development, multiple unit all-ceramic anterior and posterior fixed partial dentures are clearly in the future.

Cementation↗
PubMed1999

Toward a framework for computer-mediated collaborative design in medical informatics.

The development and implementation of enabling tools and methods that provide ready access to knowledge and information are among the central goals of medical informatics. The need for multi-institutional collaboration in the development of such tools and methods is increasingly being recognized. Collaboration involves communication, which typically involves individuals who work together at the same location. With the evolution of electronic modalities for communication, we seek to understand the role that such technologies can play in supporting collaboration, especially when the participants are geographically separated. Using the InterMed Collaboratory as a subject of study, we have analyzed their activities as an exercise in computer- and network-mediated collaborative design. We report on the cognitive, sociocultural, and logistical issues encountered when scientists from diverse organizations and backgrounds use communications technologies while designing and implementing shared products. Results demonstrate that it is important to match carefully the content with the mode of communication, identifying, for example, suitable uses of E-mail, conference calls, and face-to-face meetings. The special role of leaders in guiding and facilitating the group activities can also be seen, regardless of the communication setting in which the interactions occur. Most important is the proper use of technology to support the evolution of a shared vision of group goals and methods, an element that is clearly necessary before successful collaborative designs can proceed.

Communication↗