SEARCH · PubMed Health

Results for “Computer-Aided Design”

Explore indexed PubMed citations for clinical trials, systematic reviews and public health research. Read source abstracts and follow each citation to its original PubMed record.

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

At least 91 records · Page 5Linked to original sources

PubMed1992

Real-time quantitative elemental analysis and mapping: microchemical imaging in cell physiology.

Recent advances in widely available microcomputers have made the acquisition and processing of digital quantitative X-ray maps of one to several cells readily feasible. Here we describe a system which uses a graphics-based microcomputer to acquire spectrally filtered X-ray elemental image maps that are fitted to standards, to display the image in real time, and to correct the post-acquisition image map with regard to specimen drift. Both high-resolution quantitative energy-dispersive X-ray images of freeze-dried cyrosections and low-dose quantitative bright-field images of frozen-hydrated sections can be acquired to obtain element and water content from the same intracellular regions. The software programs developed, together with the associated hardware, also allow static probe acquisition of data from selected cell regions with spectral processing and quantification performed on-line in real time. In addition, the unified design of the software program provides for off-line processing and analysing by several investigators at microcomputers remote from the microscope. The overall experimental strategy employs computer-aided imaging, combined with static probes, as an essential interactive tool of investigation for biological analysis. This type of microchemical microscopy facilitates studies in cell physiology and pathophysiology which focus on mechanisms of ionic (elemental) compartmentation, i.e. structure-function correlation at cellular and subcellular levels; it allows investigation of intracellular concentration gradients, of the heterogeneity of cell responses to stimuli, of certain fast physiological events in vivo at ultrastructural resolution, and of events occurring with low incidence or involving cell-to-cell interactions.

Animals↗

PubMed1992

The isolation and characterisation of a cDNA clone encoding L-asparaginase from developing seeds of lupin (Lupinus arboreus).

An L-asparaginase cDNA clone, BR4, was isolated from a Lupinus arboreus Sims developing seed expression library by screening with polyclonal antibodies to the seed asparaginase. The cDNA hybridised with an oligonucleotide probe designed from amino acid sequence data and was found on sequencing to be 947 bp in length. Six polypeptide sequences obtained previously could be placed along the longest open reading frame. Computer-aided codon use analysis revealed that the cDNA sequence was consistent with other plant genes in terms of codon use. The cDNA insert was used to analyse asparaginase transcription in various tissues by northern blot analysis. A transcript size of approximately 1.2 kb was detected in L. arboreus seed total and poly(A)+ RNA. The level of this transcript declined from 30 days after anthesis to an undetectable level by day 55. Furthermore, under the high stringency conditions used, the seed asparaginase cDNA did not hybridise with total or poly(A)+ RNA isolated from root tips, suggesting that the asparaginase known to be present in this tissue may be the product of a different gene. Southern analysis suggested the seed asparaginase is a single-copy gene. The plant asparaginase amino acid sequence did not have any significant homology with microbial asparaginases but was 23% identical and 66% similar (allowing for conservative substitutions) to a human glycosylasparaginase.

Amino Acid Sequence↗

PubMed1978

Preventable anesthesia mishaps: a study of human factors.

A modified critical-incident analysis technique was used in a retrospective examination of the characteristics of human error and equipment failure in anesthetic practice. The objective was to uncover patterns of frequently occurring incidents that are in need of careful prospective investigation. Forty-seven interviews were conducted with staff and resident anesthesiologists at one urban teaching institution, and descriptions of 359 preventable incidents were obtained. Twenty-three categories of details from these descriptions were subjected to computer-aided analysis for trends and patterns. Most of the preventable incidents involved human error (82 per cent), with breathing-circuit disconnections, inadvertent changes in gas flow, and drug-syringe errors being frequent problems. Overt equipment failures constituted only 14 per cent of the total number of preventable incidents, but equipment design was indictable in many categories of human error, as were inadequate experience and insufficient familiarity with equipment or with the specific surgical procedure. Other factors frequently associated with incidents were inadequate communication among personnel, haste or lack of precaution, and distraction. Results from multi-hospital studies based on the methodology developed could be used for more objective determination of priorities and planning of specific investments for decreasing the risk associated with anesthesia.

Accident Prevention↗

PubMed1975

A physiological analysis of walking in the American lobster (Homarus americanus).

The normal, unrestrained, forward walking of the lobster was studied with a closed-circuit television system and a video-tape recorder. A frame-by-frame analysis was undertaken and measurements made of unilateral stepping sequences, contralateral and ipsilateral phase relations between pairs of legs, the movements at the leg joints primarily involved in stepping and their differences in each of the four pereiopods. The order of stepping was expressed in terms of the probability of any leg following any other leg and it was found that while there is a preferred order, there is considerable variation from the dominant pattern. The commonest deviations from the dominant gait are those involving the simplest types of re-ordering of the sequence. Pairs of contralateral legs show a strong tendency to alternate but all phase relations can occur. Similarly, while the ipsilateral legs show preferred phase relations, all possible relations do occur. The four pereiopods from anterior to posterior were found to have respectively, a pulling action, a combined pulling and rowing action, a rowing action and a combined pushing and rowing action. The same parameters of stepping were recorded from animals walking on a transparent, driven treadmill and, as no significant differences were found in comparisons with results from freely moving animals, subsequent results were obtained from animals walking on the treadmill where more detailed study and manipulation could readily be made. The stepping action of the third pereiopod during forwards walking involves major movements about two joints whereas the other pereiopods move about three joints. Detailed study of the intra-leg activity was therefore confined to the third pereiopod where the simpler action considerably simplified the problems involved in collecting and analysing data. Measurements were made of the angles swept out by the joints of the third pereiopod during movement. Electromyograms were recorded from the six muscles primarily responsible for these movements and from movement transducers placed at the joints. The duration of the movements and of the bursts of acitivity in the muscles and the interrelation between different muscle bursts were measured and a computer-aided analysis made to determine the characteristic features of the inter-burst relations during stepping. While there is considerable variability from step to step, the overall activity is relatively phase-constant over a wide range of stepping frequencies. When some of the key parameters of normal walking had been characterized, changes designed to alter the sensory input to the system were imposed.

Animals↗

PubMed1992

Direct effects of progesterone and antiprogesterone on human sperm hyperactivated motility and acrosome reaction.

OBJECTIVE: To study the direct effects of progesterone (P) and its antagonist RU486 (mifepristone) on sperm hyperactivation (HA) and acrosome reaction. DESIGN: Prospective evaluation of semen samples incubated in capacitation media with P and/or RU486. SETTING: University-affiliated tertiary care center. PATIENTS: Normal healthy volunteers. INTERVENTIONS: Semen samples were incubated in media with P or RU486 alone or in combination, and aliquots were taken at 10 minutes, 1, 5, and 24 hours for HA analyses by computer-aided sperm analysis system, and at 0, 5, and 24 hours for assessment of acrosome reaction by fluorescein-labeled Pisum sativum (pea) agglutinin. MAIN OUTCOME MEASURES: HA and acrosome reaction. RESULTS: Sperm HA was significantly increased at 10 minutes by P both at 10(-7) M (9.27 +/- 1.59%; mean +/- SEM) and 10(-6) M (9.39 +/- 1.94%) when compared with untreated spermatozoa (5.62 +/- 1.59%). The stimulatory effect of P on sperm HA was transient because this was not observed after 1, 5, and 24 hours of incubation. The antiprogesterone RU486 (10(-6) M) alone had no effect and did not abolish the stimulatory effect of P on HA. The %HA was further enhanced by the addition of RU486 at 10(-6) M to P at 10(-7) M (12.43 +/- 3.31%) or P at 10(-6) M (13.52 +/- 4.10%); however, this effect was not significantly different from P alone. Coincubation of P or RU486 with spermatozoa during capacitation did not stimulate the acrosome reaction in the concentrations tested. CONCLUSION: Progesterone directly stimulates human sperm HA transiently. Progesterone has no significant effect on acrosome reaction in capacitating spermatozoa. The effects of P are rapid and not counteracted by RU486, suggesting that the mechanism of action of P may not be mediated by specific P nuclear receptors.

Acrosome↗

PubMed1992

Computer-aided diagnosis: development of automated schemes for quantitative analysis of radiographic images.

Preliminary results obtained with computer-aided diagnosis (CAD) from various radiographic examinations are very encouraging. However, CAD is still at an early stage of its development. It will be necessary to increase further the understanding of image features of normal and abnormal patterns, to establish databases, and to devise specific approaches for particular types of pathology. Although the existing schemes are designed to be applied to digital radiographs, similar techniques can be applied in the future to cross-sectional images such as CT, MRI, and ultrasound. We believe that CAD will become clinically practical in the near future.

Angiography↗

PubMed1992

Methodology for achieving pigment specifications.

The methodologies for poultry pigmentation are varied and often are not well coordinated. Differences in the ability to measure pigments, as opposed to appearance, have resulted in systems designed to deliver enough pigment to the bird based on experience in achieving and maintaining acceptable product appearance. Through the application of HPLC techniques, however, feed ingredients can be analyzed and diets can be formulated to extremely precise levels; but the effects on the final product can only be measured in gross and vague terms. New developments in computer-aided scanning and imaging systems may allow for an effective evaluation of the complex surface appearance presented by a broiler carcass and can relate subtle differences in feed formulation to the ultimate appearance of the poultry product.

Animal Feed↗

PubMed1976

[Mechanical studies on the dental bridges by the finite element method. (1)--An abutment tooth model-- (author's transl)].

Biomechanical considerations are very important to design a prosthetic appliance; however, there have been no satisfactory quantitative studies of such problems, mainly because theoretical and experimental models are unable to represent exactly the natural conditions in the mouth. The finite element method has been successfully applied in each field of applied mechanics and found to be effective for the structural analysis of the biological systems, for it has the advantage of greater versatility for modelling. Accordingly, this analytical, computer-aided method was applied to the dental bridges to evaluate the loads transmitted to the abutment tooth and the stress distributions in the supporting tissues. As the preliminary study a two-dimensional model was constructed to simulate the tooth subject to a vertical and a horizontal load and a moment at the coronal portion. The stress distributions in the tooth and the periodontal membrane and the force distributions on the socket wall were calculated for three load conditions. The tooth mobility and the center-of-rotation position were compared with actual data available in some literatures and the characteristics of tooth support were discussed in terms of three spring constants.

Dental Abutments↗

PubMed1992

Molecular modelling of the structures of endothelin antagonists. Identification of a possible structural determinant for ET-A receptor binding.

Computer-aided molecular modelling of the endothelin (ET-A) receptor antagonists, BQ-123 and BE-18257B, shows that they have very similar 3D structures. Parts of their 3D structures are also shown to match closely with that reported for residues 6-8 in endothelin-1. On the basis of these similarities (and with supporting evidence from literature data on endothelin structure-activity relationships) a structural determinant is proposed for ET-A receptor binding, and novel designs of peptide are suggested for providing more potent and selective ET-A receptor antagonists.

Amino Acid Sequence↗

PubMed1992

Hypertrophy of gonadotropin releasing hormone-containing neurons after castration in the teleost, Haplochromis burtoni.

In the African cichlid fish, Haplochromis burtoni, males are either territorial or nonterritorial. Territorial males suppress reproductive function in the nonterritorial males, and have larger gonads and larger gonadotropin-releasing hormone- (GnRH) containing neurons in the preoptic area (POA). We describe an experiment designed to establish the causal relationship between large GnRH neurons and large testes in these males by determining the feedback effects of gonadal sex steroids on the GnRH neurons. Territorial males were either castrated or sham-operated, 4 weeks after which they were sacrificed. Circulating steroid levels were measured, and the GnRH-containing neurons were visualized by staining sagittal sections of the brains with an antibody to salmon GnRH. The soma areas of antibody-stained neurons were measured with a computer-aided imaging system. Completely castrated males had markedly reduced levels of circulating sex steroids [11-ketotestosterone (11KT) and testosterone (T)], as well as 17 beta-estradiol (E2). POA GnRH neurons in castrates showed a significant increase in mean soma size relative to the intact territorial males. Hence, in mature animals, gonadal steroids act as a brake on the growth of GnRH-containing neurons, and gonadal products are not responsible for the large GnRH neurons characteristic of territorial males.

Animals↗

PubMed1992

Isoresponse time regions for the evaluation of visual search performance in ergonomic interface models.

Computer-aided ergonomic evaluation models often provide a limited function of visual performance, usually in the form of visibility tests at any given location. It is, however, of great importance to complete a visual task in a predetermined time successfully or to predict the time to complete the task, e.g., a task of high-level control such as aircraft flight operations. In this study, isoresponse time regions which have an effect on visual performance in real-life situations are presented as an effort to complement aforementioned shortcomings of ergonomic interface models. A multiple regression was used to provide equal response time regions, being asymmetrical in shape. In addition, the fuzzy linear regression (FLR) model was introduced to provide a fuzzy set from which a decision-maker might select appropriately. It provided similar fitted values with having the advantage of utilizing the interval of those fitted values over the conventional regression model. The results can be applied effectively to the design of an interface for diverse visual tasks in real situations.

Adult↗

PubMed1992

Computer-assisted three-dimensional volumetry of the human pulmonary acini.

Computer-aided three-dimensional (3-D) volumetry of human pulmonary acini was undertaken using the left upper lobe of a 51-year-old female operated for small lung cancer. A normal part of this lobe, fixed by intrabronchial infusion with a mixture of polyethylene glycol and formalin, was subjected to serial sectioning, using a special slicer, into 48 serial slices of 0.5 mm in thickness. A soft x-ray radiograph was prepared from each slice at x 12, and the contours of airways and acinar boundaries contained in it were input by digitization into a microcomputer for 3-D reconstruction and volumetry. The estimated volumes of 130 acini were unexpectedly uniform, showing a normal type distribution with a mean of 172.7 +/- 37.9 mm3. No significant correlation proved to exist between the volume of acini and the number of branching generation of the terminal bronchioles (TBs) they received. Furthermore, there was no significant difference in volume among the acini facing the costal surface, those facing the mediastinal surface and those not facing any pleural surface. However, the generation number of TBs was shown to differ significantly with the location of acini. These results suggest that the tree of conductive airways is designed so as to meet the requirement of constant acinar volume.

Adenocarcinoma↗

PubMed1975

Computer-aided diagnosis of "dyspepsia".

Experience with computer-aided diagnosis of "dyspepsia" in a consecutive prospective series of 212 patients coming to surgery is described. Analysis is concentrated upon 122 patients who presented to an outpatient clinic de novo for diagnosis. During their first (outpatient) hospital contact, a firm diagnosis was made in just over half of these patients (though where made, it was usually correct). After full investigation, the diagnostic accuracy (prior to operation) was 92.6%. Using data elicited solely from the house surgeon's interview at the time of admission, the computer's overall diagnostic accuracy was 87.7%. The cost of each new computer diagnosis was around 25 new pence ($0.60). and the time taken was about 5 minutes. In a further small series designed to discriminate between organic and functional dyspepsia, the computer correctly assigned all but 1 of 23 patients with organic disease to the correct disease category. However, almost half of 33 patients with x-ray negative dyspepsia were predicted by the computer to have organic lesions. Time alone will tell whether the computer is a better early predictor of eventual organic disease than currently available radiologic methods.

Bayes Theorem↗

PubMed1992

Computer-aided optimization of choice and positioning of bone plates and screws used for internal fixation of mandibular fractures.

The present study describes a biomechanical integrated model of the mandibular system in which the maxilla and mandible, the masticatory muscles, and the temporomandibular joints are regarded as one system. In this model, strains in plate-osteosynthesis devices for internal fixation of mandibular fractures can be minimized by optimizing their positions. The model evaluates maximal bite force strategies on all possible dental elements; it uses a linear programming technique and a muscle architecture model, resulting in muscle recruitment patterns. The shape of a "standard" lower jaw is digitized by means of a three-dimensional (3-D) coordinate retrieval device and drawn on a computer screen after its dimensions have been changed according to the clinical case at hand. The 3-D location of the fracture as well as the anatomic restrictions for screw placement can be indicated on the screen. Osteosynthesis devices can be indicated in terms of dimensions, number, and material properties.

Biomechanical Phenomena↗

PubMedDate not supplied

Bayesian statistics: a guided tour.

An overview of Bayesian statistical decision theory is presented in the tutorial spirit. A section on fundamental principles is followed by selected applications of the Bayesian approach to parameter estimation, pattern recognition, image processing, computer-aided medical diagnosis, optimal diagnostic test selection, and radiotherapy treatment planning.

Decision Making↗

PubMed1992

Patch test results of the Dermatology Clinic Zurich in 1989: personal computer-aided statistical evaluation.

The patch test results of 921 consecutively tested patients were registered on an IBM personal computer. A computer program based on the dBase III plus database software, especially designed for this purpose, was used. The statistical evaluation was performed with dBase III plus. 59% of the probands were females and 41% males. The average age was 42.8 years. 26% of the probands were inpatients and 74% outpatients. A majority of the patients presented with eczema of the hands, face or the lower legs. The largest occupational groups were houseworkers and cleaning personnel, office workers and pensioners. To 450 of the 921 patients, at least 4 test series were applied simultaneously. These included European standard, vehicles and emulgators, topical medications, and preservatives and biocides. The other 20 test series available were employed only by 2-81 patients each. The highest sensitization rates were found with: nickel, 18.7%; cobalt, 10.2%; balsam of Peru, 8.8%; framycetin, 8.0%; neomycin, 6.8%; potassium dichromate, 6.1%; p-phenylene diamine, 5.4%; paramix, 4.9%; formaldehyde, 4.8%, and (chlor)methylisothiazolinone, 4.7%. The critical evaluation of the data showed two kinds of problems: first, test-specific aspects led to optimization of the patch test procedures; second, the crucial importance of an adequate statistical analysis for epidemiological investigation was revealed.

Adolescent↗

PubMed1992

A comparison of conventional intra-oral radiography and computer imaging techniques for the detection of proximal surface dental caries.

The detection of proximal surface caries by the visual interpretation of bitewing radiographs is known to be relatively inaccurate. The present study was designed to examine whether computer image processing could improve the diagnostic accuracy. A computer-aided, software-driven, TV-based system was used to digitize conventional radiographs and digitally process the images using histogram equalization and grey-scale inversion to enhance the images. The computer-enhanced images were compared with conventional intra-oral radiographs for the detection of proximal surface caries using receiver operating characteristic analysis. The results indicate that the digital image processing techniques used did not improve the diagnostic accuracy of dental radiographs. No significant difference in diagnostic accuracy could be detected between the non-enhanced digital images and conventional film-based images for the detection of proximal surface caries.

Dental Caries↗

PubMed1992

[Computer-aided prediction of optimal composition of multicomponent mobile phase in high performance liquid chromatography].

This paper proposed a systematic optimizing method for the composition of multicomponent mobile phase in high performance liquid chromatography. A new chromatographic response function (CRF) has been constructed according to the fundamental retention equation and rule of peak width at half-height, and the optimal composition of multicomponent mobile phase can be automatically predicted by a computer with CRF. This paper improved the known complex method, therefore, the optimal mobile phase composition in the global area may be found by means of this modified complex method. The optimal separation conditions of four vitamins and three nitrophenols were determined by use of the optimizing method reported in this paper. The results predicted by the computer were verified by the experimental data obtained in HPLC using ternary mobile phase.

Chromatography, High Pressure Liquid↗