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PubMedDate not supplied

User discipline in a personal computer-based filing of ultrasound records.

The discipline of entering ultrasound examination data in a personal computer file was studied over two periods. During the first period (19 weeks), the use of the computer was limited to one laboratory. During the second period (14 weeks), the computer was shared by three laboratories operating in nearby premises. During the study, 2857 (89%) of a total of 3209 ultrasound examinations performed were duly recorded in the data file. The frequency of failure to enter data was markedly higher during the second period (7-45%) than during the first period (5%) of the study. Overall, there was a highly significant (p less than 0.001) tendency to enter pathological findings at the expense of normal and non-diagnostic findings. The ease of access to the computer and the number of examinations recorded appear to determine user conscientiousness in filing data. Selection and omission of data impair the usefulness of the data log in research.

Humans↗

PubMed1994

Transport properties of single-file pores with two conformational states.

Complex facilitative membrane transporters of specific ligands may operate via inner channels subject to conformational transitions. To describe some properties of these systems, we introduce here a kinetic model of coupled transport of two species, L and w, through a two-conformational pore. The basic assumptions of the model are: a) single-file of, at most, n molecules inside the channel; b) each pore state is open to one of the compartments only; c) there is at most only one vacancy per pore; d) inside the channel, a molecule of L occupies the same positions as a molecule of w; and e) there is at most only one molecule of L per pore. We develop a general representation of the kinetic diagram of the model that is formally similar to the one used to describe one-vacancy transport through a one-conformational single-file pore. In many cases of biological importance, L could be a hydrophilic (ionic or nonionic) ligand and w could be water. The model also finds application to describe solute (w) transport under saturation conditions. In this latter case, L would be another solute, or a tracer of w. We derive steady-state expressions for the fluxes of L and w, and for the permeability coefficients. The main results obtained from the analysis of the model are the following. 1) Under the condition of equilibrium of w, the expression derived for the flux of L is formally indistinguishable from the one obtainable from a standard four-state model of ligand transport mediated by a two-conformational transporter. 2) When L is a tracer of w, we can derive an expression for the ratio between the main isotope and tracer permeability coefficients (Pw/Pd). We find that the near-equilibrium permeability ratio satisfies (n - 1) < or = (Pw/Pd)eq < or = n, a result previously derived for the one-conformational, single-file pore for the case that n > or = 2. 3) The kinetic model studied here represents a generalization of the carrier concept. In fact, for the case that n = 1 (corresponding to the classical single-occupancy carrier), the near-equilibrium permeability ratio satisfies 0 < or = (Pw/Pd)eq < or = 1, which is characteristic of a carrier performing exchange-diffusion.

Binding Sites↗

PubMed1995

Comparison of three files to prepare curved root canals.

Flex-R, Ultra-Flex (Ni-Ti construction), and K-type files were compared using a circumferential filing technique on 96 extracted human maxillary molars. Buccal canals with minimal initial curvature of 24 degrees were used. The maximal initial curvature was 52 degrees. Canal curvature was measured before and after filling, and changes were analyzed statistically. The angle of curvature was better maintained with the Flex-R and Ultra-Flex files.

Analysis of Variance↗

PubMed1990

A comparison of techniques for cleaning endodontic files after usage: a quantitative scanning electron microscopic study.

One-hundred ten new endodontic files were used to prepare canals and were then cleaned using three different techniques: (a) gauze soaked with alcohol, (b) sponge soaked with alcohol, and (c) ultrasonic bath. The cleaning ability of each of these techniques immediately after use and after 1 h of delay were compared. Identical areas on each file were examined by using a custom-made jig. Morphometric analysis of debris was carried out using a Bioquant image analysis system. Sponge/alcohol was the worst cleaning method; this was significantly different from the other two techniques. The gauze/alcohol and ultrasonic bath were similar. The 1-h delay before instrument cleaning did not affect the ability of any of the techniques tested. None of the methods tested were able to totally clean the files.

Decontamination↗

PubMed1990

High precision, simulated cutting efficiency measurement of endodontic root canal instruments: influence of file configuration and lubrication.

A high precision method is presented for measurement of root canal instrument cutting efficiency in pure, linear movements. Operator-independent instrumentation is achieved by means of an automatic, mechanical test rig mounted as an accessory in an Instron tensile testing machine. It is now possible to do reliable cutting simulation that closely represents clinical motions. Cutting efficiency is assessed via "wear" volume measurement by means of three-dimensional surface mapping on bovine bone serving as a dentin substitute. A volume precision of 3 x 10(-3) mm3 is achieved which is equivalent to a weight resolution better than 10 micrograms. In particular, cutting efficiency data for K-type and H-type files is presented showing an enhanced performance (by roughly a factor of 3) in the latter case. Lubrication is also shown to increase the cutting efficiency (+200% for the K file and +30% for the H file). Water and 2.5% sodium hypochlorite solutions have equivalent effects.

Animals↗

PubMed1990

Comparison of balanced forces, endosonic, and step-back filing instrumentation techniques: quantification of extruded apical debris.

Randomly assigned groups of 15 single-canal, extracted human teeth were instrumented by one of three techniques: balanced forces, endosonic, or step-back filing. Debris extruded from the apical foramen during instrumentation was collected onto preweighed filters using a suction filtration apparatus. Following desiccation, weight determinations were made on an analytical electrobalance. A one-factor analysis of variance was performed on the debris weight data revealing that the endosonic technique apically extruded significantly more debris than the balanced forces technique (p less than 0.05). Further analysis of the data, excluding debris weights greater than 1 SD from the mean, using a one-factor analysis of variance revealed the balanced forces technique apically extruded significantly less debris than either endosonic or step-back filing techniques (p less than 0.05). No significant difference was demonstrated between endosonic and step-back filing techniques.

Analysis of Variance↗

PubMed1996

A comparison of canal preparation using the K-file and Lightspeed in resin blocks.

Twenty-four resin blocks with simulated curved canals of approximately 38 degrees were divided into two groups of 12 each. One group was instrumented with stainless steel K-files and the other group with nickel-titanium Lightspeed Rotary instruments. The efficiency of canal preparation was evaluated at 1, 3, 5, and 7 mm from the apex using magnified images (x4) of the radiographed blocks. The results showed that K-files caused more widening at the apical end, with a higher incidence of transportation, zipping, and elbow formation. The Lightspeed instrument stayed centered in the canals maintaining the central axis, with minimal incidence of transportation, elbow formation, and zipping. Thus, the Lightspeed instrument may be considered more suitable for efficient preparation of curved canals than the K-type file.

Dental Instruments↗

PubMed1998

Microscopic evaluation of three endodontic files pre- and postinstrumentation.

K-type files, Sureflex NiTi files, and FlexoFiles were evaluated morphometrically as they come from the manufacturer, and after being used to instrument root canals 1, 3, and 5 times in maxillary premolars. Evaluation was made using a stereomicroscope at x40 magnification and photomicrographs. The abnormalities found after instrumentation were submitted for statistical analysis. It was concluded that small-sized stainless-steel instruments should be discarded after one use. On the other hand, #30 stainless-steel K-files could be used up to three times and #30 stainless-steel FlexoFiles up to five times. Sureflex NiTi instruments, even after five times, did not show appreciable abnormalities in shape. It is strongly recommended that small-sized nickel-titanium instruments should be discarded after five uses.

Alloys↗

PubMed1999

Effects of simulated clinical conditions on nickel-titanium rotary files.

When rotary nickel-titanium files are used in highly curved canals, there is a significant risk of separation. This study exposed files to saline or 5.25% NaOCl, while freely rotating in axial motion with a range of approximately equal to 6 mm at 150 rpm for 30 s in a 1.5 mm inner diameter, thin-walled metal tube of 15 mm length with a 90 degrees curve and a 5 mm radius of curvature. Files of 0.04 taper; 25 mm length; and in ISO sizes 25, 30, and 35 were each used three times. Groups were sterilized in a Chemiclave at 132 degrees C for 30 min after each use or tested without sterilization. Controls were not subjected to simulated use. Torsional moment (N-cm) and angular deflection (degrees) at failure was determined on a Torsiometer/Memocouple. Data (n = 5) were analyzed by analysis of variance. Tukey-Kramer intervals at the 0.05 significance level were determined. Exposure to cyclic fatigue, irrigants, and sterilization did not consistently affect torsional moment or angular deflection, compared with controls. Torsional moment significantly increased with an increase in size, regardless of condition (unsterilized vs. sterilized) or solution (saline vs. NaOCl).

Analysis of Variance↗

PubMed1999

Building quantitative stereology data files with scion image, a public domain image processing and analysis software.

Two-dimensional data obtained from a histological cross-section of a tissue can be utilized to obtain three-dimensional information by the methods of quantitative stereology. The resulting quantitative information is useful in both experimental studies and whole-animal investigations for regulatory and safety purposes. Quantitative stereologic analysis requires considerable data collection and calculation and is thus practical only through the use of computer hardware and software. We have previously reported the development of a program, STEREO, which compiles data from carcinogenesis experiments, recording information from tissue sections for the estimation of the number of altered hepatic foci (AHF) per liver and the volume fraction of AHF in liver on a three-dimensional basis. The data file itself was built by measuring tissue and focal transections through a slide-reading process that involved the manual use of a digitizer. In order to increase the speed and efficiency of the analytical process, we have integrated the STEREO program with a public domain software, Scion Image. This software integration involves two portions: the building macros and the interface. Macros for quantitative stereology used in Scion Image were written to customize and simplify the measurement and to generate data needed for building each of the data files. An interface program, BuildFi.exe, was developed to receive data generated from Scion Image and to align sequential tissue plots from up to four serial sections stained with different markers. As a result, the user can store data on a disk in the format of the STEREO data files. By combining STEREO with Scion Image, the slide-reading process is simplified and can be performed automatically. It has proven to be more objective, time saving, and efficient than all earlier versions.

Animals↗

PubMed2003

Conversion of teaching file cases from film to digital format: a comparison between use of a diagnostic-quality digitizer and use of a flatbed scanner with transparency adapter.

RATIONALE AND OBJECTIVES: The authors' institution had decided to convert its radiology teaching files from film to digital media. This study was performed to determine the simplest method for converting the analog film images to digital images without a subsequent loss in diagnostic accuracy. MATERIALS AND METHODS: Twenty chest radiographs that demonstrated interstitial lung disease were randomly selected from the departmental teaching files and matched with 20 control radiographs from healthy adults. Analog film images were converted with both a diagnostic-quality film image digitizer (digitized) and a flatbed scanner equipped with a transparency adapter (scanned). Three radiology faculty members reviewed a mixed set of corresponding analog film, digitized, and scanned images. Reviewers judged whether each image depicted interstitial lung disease, indicated their level of confidence in the diagnosis, and rated each image for quality. Image quality was assessed by each reviewer subjectively at the time of viewing the individual image, without regard to other images. A one-way analysis of variance was performed to determine whether there was a statistically significant difference in diagnostic accuracy between the three image formats. Agreement in diagnosis between corresponding images in the three different formats was evaluated for each reviewer with the McNemar test. RESULTS: There was no statistically significant difference in diagnostic accuracy between analog film and scanned images, but there was such a difference between these two groups and digitized images. Accuracy was 97% for analog film, 94% for scanned, and 89% for digitized images. Results of the McNemar test showed no statistically significant difference in agreement between the analog film images and the scanned images for any of the reviewers (P > .05). CONCLUSION: A high-end flatbed scanner with transparency adapter provided accurate, simple, and inexpensive conversion of analog film teaching files to digital format, with no loss of the ability to detect or diagnose subtle abnormalities such as interstitial lung disease.

Adult↗

PubMed1999

Effect of sterilization on the cutting efficiency of rotary nickel-titanium endodontic files.

OBJECTIVE: Nickel-titanium instruments that offer greater flexibility than instruments made of other metallic materials have been developed. This study evaluated the behavior in vitro of nickel-titanium rotary instruments under repeated sterilization cycles. STUDY DESIGN: To investigate changes in cutting ability and superficial alterations, 36 ProFile instruments, 18 with a taper of .04 and 18 with a taper of .06, were exposed to different sterilization cycles. Samples were divided into 3 groups of 12 files each. The 12 group A samples were exposed to 14 cycles of sterilization for 30 minutes; the 12 group B samples were exposed to 7 cycles of sterilization for 30 minutes; the 12 group C samples were not sterilized and served as a control group. Chemical compositions of the near surface layers of samples of each group were determined by means of Auger spectroscopy. RESULTS: The instruments that underwent the greatest number of sterilizations (group A) showed in-depth distributions of chemical composition that were different from those seen in the control group; this was the result of greater amounts of titanium oxide on the surfaces of the sterilized instruments. The files of group A showed a decrease in cutting efficiency in comparison with those of the control group. CONCLUSIONS: On the basis of this research on nickel-titanium files, we determined that repeated sterilizations under autoclave alter the superficial structure of such instruments.

Dental Instruments↗

PubMed2000

Cleaning efficacy of two apical preparation regimens following shaping with hand files of greater taper.

AIM: The aim of this investigation was to assess canal cleaning following shaping with hand files of greater taper. METHODOLOGY: Thirty mesial canals and 30 distal canals in mandibular molars were prepared with .08 and .10 hand files of greater taper, respectively. Following initial preparation, 0.02 instruments were used incrementally shorter in a stepback manner. In half the canals instrumentation was performed to size 35 1 mm short of the canal terminus. In the other half the series was continued through to size 60 using stepback increments of half to one millimetre as appropriate (foramen size was maintained at size 20 in all groups). Sodium hypochlorite (4.5%) and REDTA (17%) were used as irrigants for all groups. Cleaning efficacy was evaluated by scoring the amount of remaining debris using a light microscope (x50) and calibrated eyepiece micrometer (range 0-3). RESULTS: Canals stepped back through to a size 60 were significantly cleaner than those instrumented to a size 35 only (Mann-Whitney P < 0.05). CONCLUSION: Refining the apical region of canal preparation by stepping back through to a size 60 reduced remaining debris following shaping with files of greater taper.

Dental Instruments↗

PubMed2002

The national fetal death file.

The most comprehensive source of US data on fetal deaths of 20 gestational weeks or greater is available through the National Vital Statistics System (NVSS). The NVSS is a collaborative effort between the independent reporting areas (the individual States and the territories), and the federal government or its agent, the Centers for Disease Control, and Prevention's National Center for Health Statistics (NCHS). The federal government has no authority to register vital events. The registration of births, deaths, fetal deaths, marriages, and divorces is solely a state responsibility. However, NCHS is mandated by law to produce national data based on vital events. To promote the uniformity necessary to create a national file from this decentralized system, NCHS attempts to influence state systems via the development of certain standards, primarily, The Model State Vital Statistics Act and Regulations (The Model Law), and the Standard Certificates and Reports. The Model Law definitions for live birth, fetal death and induced termination of pregnancy are based on international standards set by The World Health Organization. All states have definitions of fetal death consistent with the Model Law. The Model Law also recommends reporting requirements for fetal death, but state requirements vary. This variation results in differences in reporting of fetal deaths among areas. Other limitations to the national fetal death file include: the under-reporting of fetal deaths incidence, higher than acceptable levels of missing data for some items, and the accuracy of the data reported. Also of concern is the potential misclassification of fetal deaths and short-lived live births. These limitations are amenable to improvement. The upcoming revision of the US Standard Report of Fetal Death addresses these issues and offers an opportunity to strengthen the quality of fetal death data. The development of worksheets, detailed specifications and instruction manuals, and a reformatted cause of death section should importantly enhance the quality of national fetal death file and ultimately reduce the incidence of these tragic events.

Cause of Death↗

PubMed1980

Design of a computerized chemical information file in response to the initial inventory requirements of TSCA.

A computerized file of chemical information, "CHEMFO", was developed at BASF Wyandotte Corporation to help comply with the initial reporting requirements of the Toxic Substances Control Act. This organization and approach allowed collecting the required information on all the manufactured and imported chemicals, editing and entry of the data, structuring of the computer file and interactive capabilities, and selecting the final program and subsequent printout. Besides using this system to meet the TSCA initial inventory reporting requirements, the file also has the capacity to be updated and revised as needed, which further expands its potential benefits. Some of the other information that can be derived from this system are: identification of chemical substances, quantities, and each site; tie-in to the medical/occupational health data bank; foundation for recording the industrial hygiene monitoring data; supplement for toxicology and environmental data base; and index for generating compilation of site specific material on health and environmental information.

Chemical Industry↗

PubMed1995

A rapid retrieval tool for operating on large, flat archive files.

Computer-aided sequencing and analysis facilities need to efficiently search flat archive files. Retrieval by e-mail or network server connections can become impractical in cases where large numbers of selected entries need to be accessed. Public versions of these archives can be retrieved via ftp and installed on a local hard disk as an alternative to network-based retrieval. After installation, a scheme is required for rapid access of the archive that is consistent with the other production needs of the sequencing facility. We have developed a retrieval system for entries inside a flat-file database. The system works for any flat-file database system such as those used in the public DNA and protein archives.

Animals↗

PubMed1997

NEXUS: an extensible file format for systematic information.

NEXUS is a file format designed to contain systematic data for use by computer programs. The goals of the format are to allow future expansion, to include diverse kinds of information, to be independent of particular computer operating systems, and to be easily processed by a program. To this end, the format is modular, with a file consisting of separate blocks, each containing one particular kind of information, and consisting of standardized commands. Public blocks (those containing information utilized by several programs) house information about taxa, morphological and molecular characters, distances, genetic codes, assumptions, sets, trees, etc.; private blocks contain information of relevance to single programs. A detailed description of commands in public blocks is given. Guidelines are provided for reading and writing NEXUS files and for extending the format.

Animals↗

PubMed1993

Comparison of a videodisc system with a conventional film file for medical student teaching.

PURPOSE: The authors assessed the effectiveness of a videodisc film file compared with a conventional film file for teaching radiology to medical students. METHODS: Fourth-year medical students (N = 134) studied 116 cases selected from the American College of Radiology Learning File. Half the students studied 58 skeletal cases using conventional films and half studied the same cases on a videodisc system. Student groups were then switched and those who studied skeletal cases on films studied 58 chest cases on videodisc and vice versa. Students received the same skeletal and chest tests and completed a questionnaire. RESULTS: For both skeletal and chest radiology, students studying films scored minimally higher than students using the videodisc. Students rated films superior to the videodisc for amount learned, convenience of use, and ability to detect lesions. CONCLUSIONS: Conventional film and videodisc methods resulted in similar levels of learning; however, students perceived conventional films to be a superior learning experience.

Education, Medical, Undergraduate↗