Designing hospitals in the computer age.
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Computers↗
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Results for “computational design”
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User design of a laboratory computer system.
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Computers↗
Individual prefabricated titanium implants and titanium mesh in skull base reconstructive surgery. A report of cases.
Titanium implants can be shaped by traditional hand forming, press shaping, modular construction by welding, construction on full-size models shaped from CT coordinates and, most recently, by computer-assisted design and computer-assisted manufacturing (CAD/CAM) that consist in the direct prefabrication of individual implants by milling them out of a solid block of titanium. The aim of our study was to present a set of preliminary cases of an ongoing program of reconstructive procedures of the skull base using titanium implants. The subjects underwent ablative procedures of the skull base with reconstruction either by titanium mesh or individual prefabricated CAD/CAM implants. Six patients have been operated on successfully since 2000: two received prefabricated CAD/CAM titanium plates and four others underwent reconstruction with titanium mesh. The stability of CAD/CAM plates is superior to that of mesh, thus it is more useful in reconstructing large lesions of the frontal skull base and the temporal and occipital bones. Titanium mesh was successfully used for defects smaller than 100 cm(2) or where selected viscerocranial defects are complicated in design and less reproducible by CAD/CAM. The intraoperative design, shaping and adjustment characteristic of titanium mesh can be dispensed with when CAD/CAM implants are used. The 3-D data set used in the CAD/CAM process also operates in the navigated simulation and planning of the ablation contours, the latter being of great assistance in establishing the optimal future defect. As a disadvantage, CAD/CAM technology is more expensive than titanium mesh, and the process is time-consuming as it is carried out in advance of surgery.
Adult↗
Computer-aided molecular design of novel glucosidase inhibitors for AIDS treatment.
Since the onset of the AIDS epidemic, some 20 million people have died and the estimate is that today close to 40 million are living with type 1 human immunodeficiency virus (HIV)/AIDS. About 14 thousands people are infected worldwide daily with this disease. Still, only a few pharmaceuticals are available for AIDS chemotheraphy. Some pharmaceuticals act against the virus before the entrance of the HIV into the host cells. One of these targets is the glucosidase protein. This class of enzymes has been recently explored because the synthesis of viral glycoproteins depends on the activity of enzymes, such as glucosidase and transferase, for the elaboration of the polysaccharides. In this work we study several glucosidase inhibitors. The DFT method is used to compute atomic charges and the ligand/receptor interaction was simulated with docking software. Analysis of the interactions of the proposed pharmaceutical, a pseudodisaccharide, with the Thermotoga maritima 4-alpha-glucanotransferase in complex with modified acarbose, the scores from docking as well as the graphical superposition of all the ligands, suggest that our molecular designed pseudo-disaccharide may be a potent glucosidase inhibitor.
Acarbose↗
Looking for design in materials design.
Despite great advances in computation, materials design is still science fiction. The construction of structure-property relations on the quantum scale will turn computational empiricism into true design.
Computer Simulation↗
Measurement of user performance and attitudes assists the initial design of a computer user display and orientation method.
OBJECTIVE: The objective of our study was to assess the acceptability of a proposed user interface to visually interfaced computer-assisted anesthesia record (VISI-CAARE), before the application was begun. The user interface was defined as the user display and its user orientation methods. METHODS: We designed methods to measure user performance and attitude toward two different anesthesia record procedures: (1) the traditional pen and paper anesthetic record procedure of our hospital, and (2) VISI-CAARE. Performance measurements included the reaction speed (identifying the type and time of an event) and completion speed (describing the event). Performance also included accuracy of the recorded time of the event and accuracy of the description. User attitude was measured by (1) the physician's rating on a scale of 0 to 9 of the potential usefulness of computers in anesthesia care; (2) willingness to use the future application in the clinical environment; and (3) user suggestions for change. These measurements were used in a randomized trial of 21 physicians, of which data from 20 were available. RESULTS: After exposure to VISI-CAARE, the experimental subjects' ranking of computer usefulness in anesthesia care improved significantly (4.2 +/- 1.1 to 7.6 +/- 1.5, p = 0.0001), as did controls' (5.2 +/- 2.6 to 8 +/- 1.5, p = 0.0019). All the volunteers were willing to try the proposed prototype clinically, when it was ready. VISI-CAARE exposure was associated with faster and more accurate reaction to events over the traditional pen and paper machine, and slower and more accurate description of events in an artificial mock setting. VISI-CAARE 1.1 demonstrated significant improvements in both reaction speed and completion speed over VISI-CAARE 1.0, after changes were made to the user display and orientation methods. CONCLUSION: With graphic user interface prototyping environments, one can obtain preliminary user attitude and performance data, even before application programming is begun. This may be helpful in revising initial display and orientation methods, while obtaining user interest and commitment before actual programming and clinical testing.
Anesthesia↗
An approach to computer-aided inhibitor design: application to cathepsin L.
We have developed an approach to search for molecules that can be used as lead compounds in designing an inhibitor for a given proteolytic enzyme when the 3D structure of a homologous protein is known. This approach is based on taking the cast of the binding pocket of the protease and comparing its dimensions with that of the dimensions of small molecules. Herein the 3D structure of papain is used to model cathepsin L using the comparative modeling technique. The cast of the binding pocket is computed using the crystal structure of papain because the structures of papain and the model of cathepsin L are found to be similar at the binding site. The dimensions of the cast of the binding site of papain are used to screen for molecules from the Cambridge Structural Database (CSD) of small molecules. Twenty molecules out of the 80,000 small molecules in the CSD are found to have dimensions that are accommodated by the papain binding pocket. Visual comparison of the shapes of the cast and the 20 screened molecules resulted in identifying brevotoxin b, a toxin isolated from the 'red tide' dinoflagellate Ptycho brevis (previously classified as Gymonodium breve), as the structure that best fits the binding pocket of papain. We tested the proteolytic activity of papain and cathepsin L in the presence of brevotoxin b and found inhibition of papain and cathepsin L with Kis of 25 microM and 0.6 microM, respectively. We also compare our method with a more elaborate method in the literature, by presenting our results on the computer search for inhibitors of the HIV-1 protease.
Binding Sites↗
Computer-aided rational design of catalytic antibodies: The 1F7 case.
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Antibodies, Catalytic↗
Computer-assisted quality control: considerations for program design.
A well-designed laboratory computer system has the potential of enhancing all phases of quality control. Of most importance is the choice of an underlying approach that is statistically valid and robust. Specification of quality goals, participation in regional programs, and use of a flexible multi-rule approach are recommended. Careful attention to general and specific design is necessary to achieve full system potential. The design process must include detailed consideration of file and record structure, data integrity, flexibility of input and output, and display and report formats. For statistical run evaluation, theoretic validity, operational process, and ease of understanding by the user must be considered.
Computers↗
A computer program for designing clinical trials with arbitrary survival curves and group sequential testing.
We present a program, mhghseq, for designing a clinical trial to compare two treatments. For a user-specified hypothesis and a user-specified alternative, mhghseq finds the number of subjects required to achieve a given size and power. It permits each treatment to have an arbitrary survival curve and it allows for group sequential testing. It provides solutions for small samples as well as for large samples. There may be a follow-up period after accrual is completed. Tests may be one or two-sided, either the log-rank or the Gehan test may be used, and either of two commonly used boundary forms--the O'Brien-Fleming or Pocock boundary forms--may be specified. Although mhghseq relies primarily on simulation to produce results, the large sample sequential boundary for the log-rank test optionally may be computed with an algorithm given here that is different from ones used in the past for this purpose.
Computer Simulation↗
The team approach to the design of computer-assisted learning packages in medicine.
Some of the didactic teaching of clinical medicine is now being replaced by self-directed learning, sometimes in the form of computer-assisted learning (CAL). This represents a significant change in the way medical students are taught and has implications for all those involved in medical education. This article reviews the approach of one medical school to the introduction of CAL into the teaching of some aspects of clinical medicine. It emphasizes the importance of the centralization of resources and of a multidisciplinary team approach in the design of CAL packages.
Clinical Medicine↗
Computational analyses and design improvements of graft-to-vein anastomoses.
For hemodialysis patients, arteriovenous grafts are omnipresent. Unfortunately, a large percentage of such grafts fail within the first year after surgery because of occlusive lesions mainly at the venous anastomotic site. It is textbook knowledge that critical values of certain hemodynamic parameters, such as low (oscillatory) wall shear stresses, large sustained wall shear stress gradients, significant changes in wall shear stress angles, excessive radial pressure gradients, etc., play significant roles in the onset and/or development of vascular diseases. The idea is to geometrically design graft-to-vein configurations such that aggravating flow patterns are reduced, and hence stenotic developments are minimized. Focusing on a new blood rheological model in conjunction with three graft-to-vein anastomotic configurations, that is, a base case, the Bard-IMPRA Venaflo graft, and a new graft-end design, the corresponding transient laminar 3-D hemodynamics are numerically simulated and compared. The design criterion for the best performance of these junction geometries is the most significant reduction in locally disturbed flow as expressed by equally weighted indicator functions for the onset and progression of stenotic developments. As a result of this comparison study, quantitative recommendations for arteriovenous loop graft designs toward increased patency rates are provided. The resulting improved graft design will be scrutinized in clinical trials.
Arteriovenous Shunt, Surgical↗
Production and characterization of antipeptide kallikrein 4 antibodies. Use of computer modeling to design peptides specific to Kallikrein 4.
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Amino Acid Sequence↗
Design of computer-generated hologram with ring focus for nonmechanical corneal trephination with Er:YAG laser in penetrating keratoplasty.
PURPOSE: To calculate a beam-shaping optical element for homogeneous intensity distribution within a focal ring to be used in nonmechanical trephination with the Er:YAG laser in penetrating keratoplasty instead of a spot guiding device. METHODS: The phase distribution behind a holographic optical element (HOE) k psi(u) can be described by the addition of the hologram phase phiH(u) to the beam phase phiE(u): k psi(u) = phiH(u) + phiE(u), k = 2pi/lambda, where u denotes the coordinates inside the hologram aperture, k an integer, and lambda the laser wavelength. To avoid discontinuous wavefronts leading to speckle noise, a smooth phase function is necessary. After transforming the hologram aperture coordinates into the focal plane x in a focal distance f, psi can be retrieved from the slope equation: inverted delta psi(u) = x(u) - u/f. RESULTS: Creating a ring focus can be reduced to an essentially one-dimensional problem by separation of variables due to the symmetry condition. We calculated a computer-generated eight-level phase-only HOE with 4096 x 4096 pixels from a Gaussian-distributed 2.94 Er:YAG laser spot with a beam diameter of 10 mm and a focal distance of 100 mm. Thereby, a ring focus with an inner/outer radius of 7/8 mm can be created. To avoid Poisson's spo, the symmetry of the problem was broken by circular modulation of the phase leading to a spiral-like structure. The calculated efficiency of the HOE relating the energy within the ring to the total energy was 91%. CONCLUSION: With an HOE it is possible to redistribute the energy along the desired focal ring. The HOE design can be adapted to the intensity distribution of the impinging laser beam with its characteristic aperture shape. A circular homogeneous corneal trephination depth is possible, because the energy fluctuation from pulse to pulse does not locally affect the ablation process. A ring focus for the Er:YAG laser has the potential to render superfluous a manual beam control via micromanipulator and to allow a more rapid and more regular corneal trephination along aperture masks.
Cornea↗
Human-computer interaction: psychology as a science of design.
Human-computer interaction (HCI) study is the region of intersection between psychology and the social sciences, on the one hand, and computer science and technology, on the other. HCI researchers analyze and design specific user interface technologies (e.g. pointing devices). They study and improve the processes of technology development (e.g. task analysis, design rationale). They develop and evaluate new applications of technology (e.g. word processors, digital libraries). Throughout the past two decades, HCI has progressively integrated its scientific concerns with the engineering goal of improving the usability of computer systems and applications, which has resulted in a body of technical knowledge and methodology. HCI continues to provide a challenging test domain for applying and developing psychological and social theory in the context of technology development and use.
Journal Article↗
Individual prefabricated titanium implants in reconstructive craniofacial surgery: clinical and technical aspects of the first 22 cases.
The reconstruction of craniofacial bone defects by intraoperative modeling of implants restricts the choice of material and its biocompatibility and also reduces the predictability of the aesthetic result. These shortcomings go hand in hand with a prolonged surgical procedure time and increased stress on the patient. In contrast, modern industrial computer-aided design and computer-aided manufacturing systems allow the prefabrication of titanium implants, i.e., individual computer-based three-dimensional models of the bone defect are generated after acquisition, transfer, and evaluation of helical computed tomographic data. Based on these data, the individual shape of the implant is designed using freeform-surfaces geometries and is fabricated by a numerically controlled milling machine in a direct fashion. The conical margins of this implant are designed with a precision of 0.25 mm to the borders of the defect, and the surface contours are generated harmonically to the nonaffected neighboring contours with a constant thickness of 1.5 mm. Individual constructions for fixation with the dimensions of microplates are integrated in this process if screw holes cannot be drilled in thin overlapping implant margins. The reconstruction of 22 posttraumatic, postoperative, or primary cranial and craniofacial defects measuring up to 18 cm was performed using this new method. Wound healing was uneventful in all but one case, although some of the patients had been operated on several times before. The result was always predictable and constant using this highly precise technique, and duration of surgery was reduced dramatically.
Adolescent↗
Paradigms for computational nucleic acid design.
The design of DNA and RNA sequences is critical for many endeavors, from DNA nanotechnology, to PCR-based applications, to DNA hybridization arrays. Results in the literature rely on a wide variety of design criteria adapted to the particular requirements of each application. Using an extensively studied thermodynamic model, we perform a detailed study of several criteria for designing sequences intended to adopt a target secondary structure. We conclude that superior design methods should explicitly implement both a positive design paradigm (optimize affinity for the target structure) and a negative design paradigm (optimize specificity for the target structure). The commonly used approaches of sequence symmetry minimization and minimum free-energy satisfaction primarily implement negative design and can be strengthened by introducing a positive design component. Surprisingly, our findings hold for a wide range of secondary structures and are robust to modest perturbation of the thermodynamic parameters used for evaluating sequence quality, suggesting the feasibility and ongoing utility of a unified approach to nucleic acid design as parameter sets are refined further. Finally, we observe that designing for thermodynamic stability does not determine folding kinetics, emphasizing the opportunity for extending design criteria to target kinetic features of the energy landscape.
Algorithms↗
CAN*TROL: a computer model for designing national cancer control strategies.
Planning national and regional cancer control strategies is difficult. At present, cancer experts and planners rely on global subjective judgment to estimate the effectiveness and cost of different programs, and to set priorities. The complexity of the problem makes this approach vulnerable to oversimplification and error. Computer models can be very powerful aids to planning, enabling decision makers to break a problem into parts for which data exist, and reconstructing the parts to estimate the effect of a virtually limitless variety of cancer control activities, on a large number of important clinical and economic outcomes. CAN*TROL has been developed to serve this need. CAN*TROL has been used in the U.S., Chile and India, and is scheduled for use in several other countries.
Chile↗