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TRI2SOLID: an application of reverse engineering methods to the creation of CAD models of bone segments.

For many biomechanical engineering activities it would be useful to have the three dimensional (3D) geometry of bone segments available in form of vectorial models within computer aided design (CAD) environments. In this paper a new method for the semi-automatic conversion of a stack of CT images of a femur into a CAD solid model is described. This method is relatively simple, accurate, and requires only a 3D CAD plus a few additional programs available in the public domain. The proposed method was used to convert the CT scan data set of a human femur into a valid CAD model; the resulting solid was two times more accurate than that obtained using the commonly used procedure based on 2D segmentation.

Algorithms↗

"In silico" design of potential anti-HIV actives using fragment descriptors.

Substructural Molecular Fragments (SMF) method was applied for computer-aided design of new compounds potentially possessing high anti-HIV activities: tetrahydroimidazobenzodiazepinone (TIBO) derivatives and 1-[2-hydroxyethoxy)methyl]-6-(phenylthio)thymine (HEPT) derivatives. Using available experimental data, the SMF method was first applied to build QSAR models based on fragment descriptors (atom/bond sequences and "augmented atoms"). The focused virtual combinatorial libraries containing 891 TIBO derivatives and 2640 HEPT derivatives were then generated systematically attaching selected substituents to corresponding Markush structures. Finally, a screening of those libraries using developed QSAR models led to several hits potentially possessing high anti-HIV activity.

Anti-HIV Agents↗

Sequence-selective targeting of long stretches of the DNA minor groove by a novel dimeric bis-benzimidazole.

A dimeric bis-benzimidazole molecule has been designed by computer modeling to bind to a DNA sequence via the DNA minor groove that covers a complete turn of B-DNA. A series of bis-benzimidazole dimers incorporating a -O-(CH(2))(n)()-X-CH(2))(n)()-O- linker, with n = 2 or 3 and X = O or N(+)H(Me), were screened for their capacity to fit the DNA minor groove. The modeling studies enabled an optimal linker to be devised (n = 3, X = N(+)H(Me)), and the synthesis of the predicted "best" molecule, N-methyl-N,N-bis-3,3-[4'-[5' '-(2' "-p-methoxyphenyl)-5' "-1H-benzimidazolyl]-2' '-1H-benzimidazolyl]phenoxypropylamine (5), is reported. The optimized linker permits the two symmetric bis-benzimidazole motifs to maintain hydrogen-bonded contacts with the floor of the DNA minor groove. DNase I footprinting studies have shown that this ligand binds with high affinity to sequences representing approximately a complete turn of B-DNA, represented by the [A.T](4)-[G.C]-[A.T](4) motif, and only poorly to sequences of half this site size, in accord with the computer modeling studies. Compound 5 does not show acute cellular cytotoxicity, in contrast with its monomeric bis-benzimidazole precursors, yet is rapidly taken up into cells.

Base Sequence↗

Structure-based design of selective and potent G quadruplex-mediated telomerase inhibitors.

The telomerase enzyme is a potential therapeutic target in many human cancers. A series of potent inhibitors has been designed by computer modeling, which exploit the unique structural features of quadruplex DNA. These 3,6,9-trisubstituted acridine inhibitors are predicted to interact selectively with the human DNA quadruplex structure, as a means of specifically inhibiting the action of human telomerase in extending the length of single-stranded telomeric DNA. The anilino substituent at the 9-position of the acridine chromophore is predicted to lie in a third groove of the quadruplex. Calculated relative binding energies predict enhanced selectivity compared with earlier 3,6-disubstituted compounds, as a result of this substituent. The ranking order of energies is in accord with equilibrium binding constants for quadruplex measured by surface plasmon resonance techniques, which also show reduced duplex binding compared with the disubstituted compounds. The 3,6,9-trisubstututed acridines have potent in vitro inhibitory activity against human telomerase, with EC(50) values of up to 60 nM.

Acridines↗

Computer decision support systems.

Computer decision support systems are computer applications designed to aid clinicians in making diagnostic and therapeutic decisions in patient care. They can simplify access to data needed to make decisions, provide reminders and prompts at the time of a patient encounter, assist in establishing a diagnosis and in entering appropriate orders, and alert clinicians when new patterns in patient data are recognized. Decision support systems that present patient-specific recommendations in a form that can save clinicians time have been shown to be highly effective, sustainable tools for changing clinician behavior. Designing and implementing such systems is challenging because of the computing infrastructure required, the need for patient data in a machine-processible form, and the changes to existing workflow that may result. Despite these difficulties, there is substantial evidence from trials in a wide range of clinical settings that computer decision support systems help clinicians do a better job caring for patients. As computer-based records and order-entry systems become more common, automated decision support systems will be used more broadly.

Computer Systems↗

Conquering technophobia: preparing faculty for today.

The constantly changing world of technology creates excitement and an obligation for faculty of schools of nursing to address computer literacy in the curricula at all levels. The initial step in the process of meeting the goals was to assist the faculty in becoming computer literate so that they could foster and encourage the same in the students. The implementation of The Cure for Technophobia included basic and advanced computer skills designed to assist the faculty in becoming comfortable and competent computer users. The applications addressed included: introduction to windows, electronic mail, word processing, presentation and database applications, library on-line searches of literature databases, introduction to internet browsers and a computerized testing program. Efforts were made to overcome barriers to computer literacy and promote the learning process. Familiar, competent, computer literate individuals were used to conduct the classes to accomplish this goal.

Attitude to Computers↗

Reconstruction of an extreme frontal and frontobasal defect by microvascular tissue transfer and a prefabricated titanium implant.

A 30-year-old man was referred to us with an extreme frontal and frontobasal defect from a motorbike accident 12 years before. Multiple attempts at frontal and frontobasal revision and reconstruction had been performed over the years, with several episodes of meningitis. Reconstruction was planned in two steps. First, a revision of the anterior skull base with mobilization of meningeal adhesions and duraplasty, removal of infected masses of polymethylmethacrylate out of the upper ethmoid sinuses, and coverage with a deepithelialized latissimus dorsi free flap were performed. In the second step 3 months later, aesthetic forehead reconstruction was achieved with a pre-fabricated individual titanium implant. The predictable result of this two-step reconstruction was very pleasing. Safe separation of the cranial cavity from the upper airways was essential, requiring free tissue transfer in this case, and is a prerequisite for any alloplastic forehead reconstruction. Timing of the two-step procedure, including the CT data acquisition; handling of soft tissues, bone, and foreign material; and construction details of the implant demonstrate the necessary complex management of this, the most difficult case of the 88 applications of the new computer aided design and manufacturing technique thus far. Even the most elaborate computer aided preparation cannot be successful without consideration of established surgical principles.

Adult↗

Engineering of a synthetic receptor to alter peptide binding selectivity.

BACKGROUND: Molecular recognition processes are ubiquitous in nature: substrate binding by enzymes, antigen recognition by antibodies, and hormone activation of receptors provide three classic examples. To better understand these large systems it is valuable to study smaller, well defined host molecules. Previously we found sequence-selective peptide binding with a class of C3 symmetric synthetic receptors. In this work we rationally altered that host structure in order to produce a corresponding change in binding selectivity. RESULTS: A novel C3 symmetric receptor was designed and synthesized such that, unlike previous host molecules, it contained hydrogen-bond accepting functionality within the binding cavity. Screening of this host against a combinatorial tripeptide library revealed an exquisite selectivity for sequences with D-Pro-D-Asn carboxyl termini. Computer simulations and NMR studies indicate that hydrogen bonding of the D-Asn side-chain amide to the amine functionality within the cavity is responsible for this selectivity. CONCLUSIONS: Computer-aided design and combinatorial library screening methods combine to provide a powerful approach to induce and evaluate the results of rational changes in the molecular recognition properties of molecules. Using this approach, we modified the binding properties of a class of molecules to select for hydrogen-bonding residues instead of hydrophobic residues and concomitantly increased the overall sequences selectivity. Structural studies indicate that these changes indeed result from the type of binding mode proposed as part of the initial design. This approach can increase our understanding of molecular recognition processes, and should allow the rational design of larger, more selective systems.

Computer Simulation↗

Corneal modeling.

The Corneal Modeling System is presented as an integrated instrument system designed to give the corneal surgeon the capability of measuring and designing alterations of corneal shape that are comparable to the computer-aided design (CAD) capability used in aerospace design and other industries. The system provides realtime digital video image acquisition using a high-resolution, cylindrical photokeratoscope and scanning laser slit lamp. From these digitized images, the system's computer derives topographic and pachymetric information in sufficient density to produce a continuous mathematical function that represents both the front and the back surface of the cornea. The mathematical model may then be sampled in as many points as the clinical application requires, in the form of either computer graphics or a numerical data stream to control precision machinery to make contact lenses or tissue lenses. Representative computer graphics of normal and pathologic corneal conditions are presented.

Cornea↗

Design of novel affinity adsorbents for the purification of trypsin-like proteases.

A number of ligands for the selective purification by affinity chromatography of the trypsin-like protease, porcine pancreatic kallikrein, were designed de novo by computer-aided molecular design. The ligands were designed to mimic the side-chains of a number of arginyl dipeptides and included a benzamidine moiety substituted on a triazine ring. The ligands displayed inhibitory activities against pancreatic kallikrein which mirrored the specificity constants of the dipeptides they were designed to mimic. The ligand with the highest affinity for the enzyme, an analogue of a Phe-Arg dipeptide, when immobilized to Sepharose CL-4B via a hexamethylene spacer arm, purified pancreatic kallikrein 110-fold in one step from a crude pancreatic acetone extract.

Benzamidines↗

Creation and utilization of a World Wide Web based space radiation effects code: SIREST.

In order for humans and electronics to fully and safely operate in the space environment, codes like HZETRN (High Charge and Energy Transport) must be included in any designer's toolbox for design evaluation with respect to radiation damage. Currently, spacecraft designers do not have easy access to accurate radiation codes like HZETRN to evaluate their design for radiation effects on humans and electronics. Today, the World Wide Web is sophisticated enough to support the entire HZETRN code and all of the associated pre and post processing tools. This package is called SIREST (Space Ionizing Radiation Effects and Shielding Tools). There are many advantages to SIREST. The most important advantage is the instant update capability of the web. Another major advantage is the modularity that the web imposes on the code. Right now, the major disadvantage of SIREST will be its modularity inside the designer's system. This mostly comes from the fact that a consistent interface between the designer and the computer system to evaluate the design is incomplete. This, however, is to be solved in the Intelligent Synthesis Environment (ISE) program currently being funded by NASA.

Algorithms↗

Automated QSPR through Competitive Workflow.

This paper describes a novel software architecture, Competitive Workflow, which implements workflow as a distributed and competitive multi-agent system. The implementation of a competitive workflow architecture designed to model important computer-aided molecular design workflows, the Discovery Bus, is described. QSPR modelling results for three example ADME datasets, for solubility, human plasma protein binding and P-glycoprotein substrates using an autonomous QSPR modelling workflow implemented on the Discovery Bus are presented. The autonomous QSPR system allows exhaustive exploration of descriptor and model space, automated model validation and continuous updating as new data and methods are made available. Prediction of properties of novel structures by an ensemble of models is also a feature of the system.

ATP Binding Cassette Transporter, Subfamily B, Mem↗

Optical modeling of extraoral defects.

In order to reduce the stress caused to patients by conventional methods of modeling using computed tomography (CT) or magnetic resonance imaging (MRI), an optical modeling process has been developed for extraoral defects and body areas. The selected body part is digitized using optical 3-coordinate measuring technology, providing an extensive data record. This is adapted for further use by equalizing the point clouds to obtain a Computer Aided Design (CAD) model, which is converted to a physical model by means of a stereolithographic process. With this technology, the patient's physical and psychological stress may be reduced. This article describes a technique for optical modeling of an ocular prosthesis.

Computer-Aided Design↗

Immediate definitive CAD/CAM restoration of a non-submerged implant.

Implant placement has become a widely accepted treatment for tooth replacement. There are many restorative options, but it is best for the patient and most efficient for the office if the implant is placed and restored in as few appointments as possible. If diagnosis is thorough and accurate, placing the implant and doing a definitive restoration in 1 appointment can be as predictable as the traditional 2 appointment technique. Restoring the implant with computer-assisted designed and machined porcelain can provide predictable fit, esthetics, and restoration and be clinically efficient.

Bicuspid↗

Computer diagnosis of skin disease: system design and preliminary results.

A system for computer-assisted diagnosis of dermatological disease is described. This is an 'expert system' whose knowledge base has been prepared with the aid of a dermatological specialist. The user enters the key elements of the patient's disease history and physical examination into the computer. The computer then returns a summary of the patient's medical record, and a differential diagnosis. The rules of operation by which a given diagnosis was included or rejected is accessible to the user. The system is currently being evaluated in a large dermatology clinic. Preliminary evaluation of the accuracy of diagnosis by the computer indicates that while it nearly always includes the correct diagnosis in its differential diagnosis (94% of cases), it frequently also includes diseases thought to be inappropriate (34% of diseases listed).

Diagnosis, Computer-Assisted↗

A computer assisted quality assurance model.

This article describes a modular quality assurance program that was designed for computer automation. The author explains how the quality assurance model not only meets this need but also satisfies other critical objectives, including integration with the hospital's multidisciplinary quality assurance program and minimal redundancy in developing standards and measurement criteria. Readers will benefit from ideas for refining or developing effective quality assurance programs that can also use computer technology to increase productivity.

Computers↗