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At least 325 records · Page 18Linked to original sources
PubMed1985

Versatile high-performance liquid chromatographic computer system for solvent delivery, gradient control and data acquisition using the Commodore 64 personal computer.

An interface for a high-performance liquid chromatographic system based on the Commodore 64 personal computer has been designed as an alternative to the expensive and somewhat inflexible solvent programmers and data acquisition systems offered by commercial manufacturers. The system consists of the Commodore 64 with a single disk drive and monitor, and an interface that directly controls the flow-rates of two Waters pumps for solvent delivery in either isocratic or gradient mode, as well as analog-to-digital conversion of chromatographic data and either graphic data output to a dot-matrix printer or digital-to-analog conversion for output to a chart recorder. The interface permits computer-controlled flow-rates of up to 10.0 ml/min, with an accuracy of 0.0047 ml/min at flow-rates of 4.1 ml/min and an accuracy of 0.03 ml/min at flow-rates of 10 ml/min. The software for data analysis permits tabulation of elution times and areas for the peaks in a chromatogram with an option for baseline correction. The data are stored on floppy disks together with information pertinent to the chromatogram (flow-rate, solvent composition, etc.).

Chromatography, High Pressure Liquid↗
PubMed2000

Cortical blindness in severe preeclampsia: computed tomography, magnetic resonance imaging, and single-photon-emission computed tomography findings.

BACKGROUND: Cortical blindness is a complication of severe preeclampsia, but it is unclear whether it results from cerebral vasospasm and ischemic injury or vasogenic (hydrostatic) edema due to increased capillary permeability. CASE: Reversible cortical blindness in a 33-year-old gravida 2, para 1, with severe postpartum preeclampsia after evacuation of a partial molar pregnancy at 19 weeks' gestation is presented. Initial neuroimaging studies showed hyperperfusion on head single-photon-emission computed tomography scan, which corresponded with lesions found on head computed tomography and magnetic resonance imaging scans. Follow-up neuroimaging studies 2 weeks later, by which time the patient's visual acuity had returned to normal, showed complete resolution of radiologic abnormalities. CONCLUSION: Neuroimaging studies in a woman with severe postpartum preeclampsia complicated by reversible cortical blindness showed that blindness resulted from vasogenic (hydrostatic) cerebral edema and not cerebral vasospasm.

Adult↗
PubMed1998

Computer modeling and computational toxicology in new chemical and pharmaceutical product development.

A theoretical basis for use of computer modeling and bioinformatics resources including the internet in decisions about whether to attempt synthesis and toxicology testing of new chemical or pharmaceutical products is described. Steps in the process include: (1) identification of a potentially efficacious chemical or pharmaceutical product; (2) structure-activity relationship (SAR) modeling; (3) synthesis methods and cost screening; (4) market screening for potential revenues; (5) regulatory impacts screening; (6) toxicology modeling and screening; (7) decision making about whether to attempt synthesis and testing. Some such computer modeling and screening processes are already in use. Others may reasonably be expected to be adopted in the near future. More development of structure-activity and structure-toxicity databases and therapeutic and toxicity molecular endpoints computerized libraries remains to be done. The internet is a rapidly developing source of information, but there are major problems with time-effectiveness, quality control, 'junk information' (misinformation), and deliberate 'disinformation'.

Computer Simulation↗
PubMed2002

Detection of simulated pulmonary nodules by single-exposure dual-energy computed radiography of the chest: effect of a computer-aided diagnosis system (Part 2).

OBJECTIVE: To evaluate the performance of the computer-aided diagnosis (CAD) scheme on the detection of pulmonary nodules (PNs) in single-exposure dual-energy subtraction computed radiography (CR) images of the chest, and to evaluate the effect of this CAD scheme on radiologists' detectibilaties. METHODS AND MATERIAL: We compared the detectability by the CAD scheme with the detectability by 12 observers by using conventional CR (C-CR) and bone-subtracted CR (BS-CR) images of 25 chest phantoms with a low-contrast nylon nodule. RESULTS: Both in the CAD scheme and for the observers, the detectability of BS-CR images was superior to that of C-CR images (P<0.005). The detection performance of the CAD scheme was equal to that of the observers. The nodules detected by the CAD did not necessarily coincide with those by the observers. Thus, if observers can use the results of the CAD system as a 'second opinion', their detectabilities increase. CONCLUSION: The CAD system for detection of PNs in the single-exposure dual-energy subtraction method is promising for improving radiologists' detectabilities of PNs.

Humans↗
PubMed2002

Can computers help in assessing children's postoperative pain? Initial validation of a computer-assisted interview.

BACKGROUND AND OBJECTIVE: Computers offer the potential for the assessment of children who have difficulties in communication and cannot describe pain using conventional approaches. Such approaches must be reliable and valid. As a preliminary step towards this goal, the validity and reliability of a computer-assisted pain assessment for children (MacInterview) was assessed using children with no known disabilities who had undergone surgery. METHODS: MacInterview uses body outlines and a range of different pain representations with scaling for size and intensity, and associated emotion. Following piloting with non-clinic children, the experience of acute postoperative pain was assessed for 30 children undergoing adenotonsillectomy or tonsillectomy the day following surgery using the MacInterview and three existing standardized assessment measures. Each child self-reported their current experience of postoperative pain on two occasions 30 min apart, and retrospectively on pain the previous evening in the immediate postoperative period. RESULTS: Analyses indicated good performance of MacInterview, showing positive correlations between 0.65 and 0.88 with standardized pain-intensity measures, and test-retest reliability was 0.9. Face validity was high, and children enjoyed the procedure. CONCLUSIONS: The procedure shows promise and is likely to merit further development for children showing difficulties in communication.

Child↗
PubMed2002

Computer-aided design of chiral ligands. Part III. A novel ligand for asymmetric allylation designed using computational techniques.

[reaction: see text] Computer-aided design protocols to identify new chiral ligands for reactions proceeding through well-defined transition states are outlined. Ligand families are discovered via computational screening of large structural databases such as the Cambridge Structural Database. Using this method, a novel cis-decalin ligand has been identified as a chiral auxiliary for the allylboration of aldehydes. Synthesis, resolution, and evaluation revealed that this new auxiliary provided the aldehyde facial approach upon which the design was predicated.

Computer-Aided Design↗
PubMed1986

Comparison of single-photon emission computed tomography with [123I]iodoamphetamine and xenon-enhanced computed tomography for assessing regional cerebral blood flow.

Regional CBF (rCBF) images obtained from xenon-enhanced computed tomography (XeCT) and single-photon emission computed tomography (SPECT) with N-isopropyl-p-[123I]iodoamphetamine (IMP) done with a rotating gamma-camera were compared in nine patients. Both XeCT and SPECT/IMP demonstrated flow abnormalities at all sites of infarction identified by CT, while detecting reduced rCBF in areas normal by CT in eight of the nine patients. All areas that were abnormal on XeCT were abnormal on the comparable SPECT/IMP images. The major advantages of XeCT are its greater resolution and potential for noninvasive quantitation of rCBF, while the major advantage of SPECT/IMP is its visualization of the entire brain on transverse, coronal, and sagittal sections.

Amphetamines↗
PubMed1986

Improved programs for DNA and protein sequence analysis on the IBM personal computer and other standard computer systems.

We have previously described programs for a variety of types of sequence analysis (1-4). These programs have now been integrated into a single package. They are written in the standard C programming language and run on virtually any computer system with a C compiler, such as the IBM/PC and other computers running under the MS/DOS and UNIX operating systems. The programs are widely distributed and may be obtained from the authors as described below.

Amino Acid Sequence↗
PubMed1996

Comparison of experimental and computational functional group mapping of an RNase A structure: implications for computer-aided drug design.

One relatively new computational approach to the drug discovery process involves calculating functional group maps of a target structure. Experimental functional group mapping techniques have also recently emerged. In this paper, the structure of RNase A with two bound formates (i.e. carboxylate functionalities) is used as a model system to test the computational methodology. Functional group maps of the RNase A structure were calculated using the Multiple Copy Simultaneous Search (MCSS) method and compared with experimentally determined formate and water positions. The calculations indicate that the protonation state of active-site histidines determines the ability of the enzyme to bind formate. The results also suggest an ordered binding mechanism for the two formates. An improved strategy for using the MCSS method to design new candidate ligands is discussed.

Animals↗
PubMed1978

Computer reconstructed sagittal and coronal computed tomography head scans: clinical applications.

Recent technical advances to computed tomography (CT) have enabled evaluation of the head in multiple planes. A technique that utilizes computer reconstruction of data from 3 mm contiguous transverse scans to display images in sagittal and coronal planes is described. The clinical usefulness of this technique is discussed and illustrative cases are presented. Multiple plane CT evaluation has proven a valuable adjunct to axial plane CT scanning, which can provide better definition of the extent of lesions, facilitate treatment, and improve diagnostic accuracy in many cases.

Adolescent↗
PubMedDate not supplied

Evaluation of the hepatic artery in potential donors for living donor liver transplantation by computed tomography angiography using multidetector-row computed tomography: comparison of volume rendering and maximum intensity projection techniques.

PURPOSE: To compare the volume rendering (VR) and maximum intensity projection (MIP) computed tomography angiography (CTA) techniques using multidetector-row CT for hepatic artery evaluation of potential donors for living donor liver transplantation (LDLT). METHOD: Over a 9-month period, CTA using multidetector-row CT and conventional angiography was performed in 62 consecutive potential donors for LDLT. Acquisition of arterial phase scans was initiated within 5 seconds after reaching enhancement of the descending aorta up to 70 HU as measured by a bolus-tracking technique (collimation = 1.25 mm, table speed = 7.5 mm, reconstruction interval = 0.625 mm). Postprocessing was performed on a commercially available workstation. Computed tomography angiography images of the hepatic artery were made using the VR and MIP techniques. A total of 10 to 30 images of various planes were generated to reveal the origins and branching patterns of hepatic arteries. With a 2-week interval, two reviewers separately evaluated CTA using VR and MIP techniques, specifically evaluating anatomic variations and hepatic arterial conspicuity. The results of conventional angiography were considered to represent the gold standard. The difference in postprocessing time between the two techniques was statistically analyzed by the Student t test, and the differences in arterial conspicuity and in the identified number of the hepatic artery to segment IV of the liver were analyzed by the chi2 test. RESULTS: Two CT examinations (3%) were technically inadequate for generating CTA because of respiratory motion artifact. The average times for postprocessing of VR and MIP images were 8.1 +/- 3.8 minutes and 5.0 +/- 0.7 minutes, respectively. Variations of hepatic arterial anatomy were present in 19 patients (32%) on conventional angiography. In 8 patients (13%), there was discrepancy in the variations of hepatic arterial anatomy between the two techniques: MIP was correct in 7 patients, and VR was correct in 1 patient. The dominant artery supplying segment IV was identified in 51 patients (85%) with MIP and in 39 patients (65%) with VR. There was no significant difference in conspicuity of the hepatic arteries using either the MIP or VR technique. CONCLUSION: In CTA techniques using multidetector-row CT, MIP is superior to VR for the hepatic arterial evaluation of potential LDLT donors in terms of depicting anatomic variations and postprocessing time.

Adolescent↗
PubMedDate not supplied

Multidetector-row computed tomography with three-dimensional volume rendering of pancreatic cancer: a complete preoperative staging tool using computed tomography angiography and volume-rendered cholangiopancreatography.

Volume rendering, a postprocessing computer algorithm that creates three-dimensional (3D) displays from computed tomography (CT) datasets, can create 3D cholangiographic images (volume-rendered cholangiopancreatography, or VRCP) from intravenous contrast-enhanced abdominal CT datasets without the use of a biliary contrast agent. This article illustrates the utility of VRCP in the setting of biliary obstruction due to pancreatic cancer. The 3D renderings of the intra- and extrahepatic biliary tree provide valuable information for planning biliary drainage, including the location and length of the obstruction as well as the relationship of intrahepatic ducts to liver metastases.

Adenocarcinoma↗
PubMed2001

Computer-assisted visualization of arteriovenous malformations on the home personal computer.

OBJECTIVE: Arteriovenous malformations (AVMs) are difficult lesions to treat, partly because it is difficult to formulate a three-dimensional mental image of the nidus and its supplying arteries, draining veins, and arteries of passage. Our purpose is to develop personal computer software that allows better visualization of complex, three-dimensional, connected vascular anatomy for surgical planning. METHODS: Vessels are defined from magnetic resonance angiograms and are symbolically linked to form vascular trees. The nidus of the AVM is also defined by magnetic resonance angiography. These representations of the nidus and vasculature can be viewed together in a software program that allows the user to color-code groups of vessels or to selectively turn connected groups of vessels "off" to avoid obscuring the part of the image that the user wants to observe. Structures can be viewed from any angle. The vessels can also be shown intersecting any magnetic resonance angiogram slice or superimposed upon digital subtraction angiograms obtained from the same patient. RESULTS: We report results from two patients with AVMs in which our representations were compared with the findings during surgery. Our three-dimensional vascular trees correctly depicted the relationship of the nidus to feeding vessels in three dimensions. We show findings in an additional, unoperated patient for whom vessel trees were created from three-dimensional digital subtraction angiography data and compared with a volume rendering of the original data set. CONCLUSION: Computer-assisted, three-dimensional visualizations of complex vascular anatomy can be helpful in planning the surgical excision of AVMs. Software programs that produce these images can provide important information that is difficult to obtain by traditional techniques. This imaging method is also applicable to guidance of endovascular procedures and removal of complex tumors.

Diagnosis, Computer-Assisted↗
PubMedDate not supplied

Usefulness of a saline flush for intravenous 3-dimensional computed tomography portography using multidetector-row helical computed tomography.

PURPOSE: To evaluate the clinical usefulness of a saline flush technique in improving the imaging quality of 3-dimensional computed tomography portography (3D-CTP). METHODS: To evaluate liver metastases, 58 patients were divided into 2 groups undergoing 3D-CTP with or without a saline flush. The computed tomography (CT) values of the right portal vein (RPV), left portal vein (LPV), main portal vein (MPV), and right hepatic parenchyma (RHP) were assessed. Maximum intensity projection (MIP) 3D-CTP images were evaluated by vessel visualization. RESULTS: Higher mean CT attenuation values in the RPV, LPV, MPV, and RPV-RHP were observed in the saline flush group and were statistically significant (P = 0.04, P = 0.03, P = 0.01, and P = 0.04, respectively). The difference in imaging quality between 2 groups was statistically significant (P = 0.04). In segment VIII, the ability to depict the segmental branches was significantly higher when the saline flush technique was used (P = 0.03). CONCLUSIONS: The saline flush technique increases the CT attenuation values of the portal vein and the difference in values between the portal vein and the tissue around it and improves the MIP imaging quality of 3D-CTP.

Contrast Media↗
PubMed1982

Is it time for a computer in your practice? III: Types of computer systems for medical offices.

The three basic types of medical-office computer systems have been described along with their basic advantages and disadvantages. A fourth option, that of keeping your current manual office system, may be a valid alternative. The next article of this series will discuss a method for evaluating the suitability of any computer system for your needs and will describe how to select the "best" one for you.

Computers↗
PubMed1985

Is it time for a computer in your practice? V. How to evaluate if a computer is appropriate for your practice.

In this article, a strategy for evaluating your practice in terms of its potential for computerization has been outlined. The rules that have been presented are general guidelines and exceptions may exist in any practice due to its specific needs. The use of a medical office computer consultant may help you to make this evaluation in a more effective manner. Once you have determined that your practice may benefit by the use of a computer, the next step is to select between the myriad of currently available systems. The next article in the series will be devoted to describing a method to help you select the system most appropriate for your setting.

Computers↗