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PubMed1992

Electrical impedance applied to non-invasive detection of irritation in skin.

Healthy volunteers were subjected to irritation by sodium lauryl sulphate at concentrations in the range 0.002% to 5.0% applied in Finn Chambers for 24 h. Test sites were visually assessed 1 h and 24 h after cessation of exposure. At the same times electrical impedance was measured with a new impedance device which allows non-invasive local measurements to a controlled depth. Close agreement between concentration and an irritation index calculated from electrical impedance parameters was found over the whole concentration range for most test persons. At concentrations below 0.2%, visual scores were zero. These results suggest that electrical impedance can be used as an objective tool to record irritation, and further that electrical impedance might be a more sensitive method than the commonly used visual readings.

Adolescent↗

PubMed2000

Directionality of extruded lithium fluoride thermoluminescent dosemeters in a cobalt-60 beam.

An experimental investigation of the directionality of commercially available extruded lithium fluoride (LiF:Mg,Ti) thermoluminescent dosemeters was carried out in a cobalt-60 beam at a water depth of 5 cm. One-half of a batch of 60 chips (3.1 x 3.1 x 0.9 mm3) was exposed face-on (faces perpendicular to the beam central axis), and the other half was exposed in an edge-on orientation (two edges perpendicular and faces parallel to the beam axis). Measurements show that an edge-on exposure results in a thermoluminescence reading approximately 0.9% lower than a face-on exposure. Although this is of minor importance in every day patient dosimetry, it is relevant in evaluating errors in in-phantom dosimetric measurements where greater accuracy is required.

Calibration↗

PubMed2000

The use of bispectral analysis to monitor outpatient sedation.

The bispectral (BIS) index has been used to interpret partial EEG recordings to predict the level of sedation and loss of consciousness in patients undergoing general anesthesia. The author has evaluated BIS technology in determining the level of sedation in patients undergoing outpatient deep sedation. These experiences are outlined in this review article. Initially, the correlation of the BIS index with traditional subjective patient evaluation using the Observer's Assessment of Alertness and Sedation (OAA/S) scale was performed in 25 subjects. In a second study, the recovery profile of 39 patients where the BIS was used to monitor sedation was compared with a control group where the monitor was not used. A strong positive relationship between the BIS and OAA/S readings was found in the initial subjects. From the recovery study, it appears that use of the BIS monitor may help titrate the level of sedation so that less drugs are used to maintain the desired level of sedation. A trend to earlier return of motor function in BIS-monitored patients was also demonstrated. BIS technology offers an objective, ordinal means of assessing the depth of sedation. This can be invaluable in comparing studies of techniques. The BIS index provides additional information to standard monitoring techniques that helps guide the administration of sedative-hypnotic agents. The trend to earlier return of motor function in BIS-monitored patients warrants further investigation.

Adolescent↗

PubMed2003

Real-time quantitative PCR for analysis of genetically mixed infections of malaria parasites: technique validation and applications.

A technique that can distinguish and quantify genetically different malaria parasite clones in a mixed infection reliably and with speed and accuracy would be very useful for researchers. Many current methods of genotyping and quantification fall down on a number of aspects relating to their ease of use, sensitivity, cost, reproducibility and, not least, accuracy. Here we report the development and validation of a method that offers several advantages in terms of cost, speed and accuracy over conventional PCR or antibody-based methods. Using real-time quantitative PCR (RTQ-PCR) with allele-specific primers, we have accurately quantified the relative proportions of clones present in laboratory prepared ring-stage mixtures of two genetically distinct clones of the rodent malaria parasite Plasmodium chabaudi chabaudi. Accurate and reproducible measurement of the amount of genomic DNA representing each clone in a mixture was achieved over 100-fold range, corresponding to 0.074% parasitised erythrocytes at the lower end. To demonstrate the potential utility of this method, we include an example of the type of application it could be used for. In this case, we studied the growth rate dynamics of mixed-clone infections of P. chabaudi using an avirulent/virulent clone combination (AS (PYR) and AJ) or two clones with similar growth rate profiles (AQ and AJ). The modification of the technique described here should enable researchers to quickly extract accurate and reliable data from in-depth studies covering broad areas of interest, such as analyses of clone-specific responses to drugs, vaccines or other selection pressures in malaria or other parasite species that also contain highly polymorphic DNA sequences.

Alleles↗

PubMed1999

The display of photographic-quality images on the Web: a comparison of two technologies.

Downloading medical images on the Web creates certain compromises. The tradeoff is between higher resolution and faster download times. As resolution increases, download times increase. High-resolution (photographic quality) electronic images can potentially play a key role in medical education and patient care. On the Internet, images are typically formatted as Graphics Interchange Format (GIF) or the Joint Photographic Experts Group (JPEG) files. However, these formats are associated with considerable data loss in both color depth and image resolution. Furthermore, these images are available in a single resolution and have no capability of allowing the user to adjust resolution as needed. Images in the photo compact disc (PCD) format have higher resolutions than GIF or JPEG, but suffer the disadvantage of large file sizes leading to long download times on the Web. Furthermore, native web browsers are not currently able to read PCD files. The FlashPix format (FPX) offers distinct advantages over the PCD, GIF, and JPEG formats for display of high-resolution images on the Web. A Java applet can be easily downloaded for viewing FPX images. FPX images are higher resolution than JPEG and GIF images. FPX images offer rich resolutions comparable to PCD images with shorter download times.

Internet↗

PubMedDate not supplied

Practical methods of electron depth-dose measurement compared to use of the NACP design chamber in water.

Central axis relative dose versus depth measurements were performed using two different small volume thimble ionization chambers and a p-type silicon diode in a water phantom and with two parallel-plate ionization chambers, thermoluminescent dosimeters, and radiographic film in a popular clear polystyrene phantom. Values obtained were compared to the results of similar measurements in a water phantom performed with a plane-parallel ionization chamber designed and optimized for use in electron beams by the Nordic Association of Clinical Physicists (NACP). The NACP chamber is expected to minimally perturb the electron fluence and be least prone to point of measurement uncertainties. Its use in a water phantom closely approximates the spirit of recent international protocols. Data were obtained for the foil scattered electron beams generated by two different accelerators for field sizes from 6 cm X 6 cm to 25 cm X 25 cm and energies between 6 and 20 MeV. Easily identifiable effective points of measurements were defined for each measurement device and standard corrections were applied to the raw data to obtain depth-dose curves. The degree of agreement between the various techniques and the NACP-water standard was quantitatively analyzed through comparison of the resulting depths of 50% dose and practical range. All methods were found to yield reasonable results when carefully implemented, with average differences of less than 1 mm being easily achievable. Measurements with p-type silicon diode detectors were found to be particularly useful, as they are pointlike and appear from all practical considerations to directly represent relative dose, thus requiring little or no correction to raw readings.

Air↗

PubMed1995

Arrangement and nucleotide sequence of the gene (fus) encoding elongation factor G (EF-G) from the hyperthermophilic bacterium Aquifex pyrophilus: phylogenetic depth of hyperthermophilic bacteria inferred from analysis of the EF-G/fus sequences.

The gene fus (for EF-G) of the hyperthermophilic bacterium Aquifex pyrophilus was cloned and sequenced. Unlike the other bacteria, which display the streptomycin-operon arrangement of EF genes (5'-rps12-rps7-fus-tuf-3'), the Aquifex fus gene (700 codons) is not preceded by the two small ribosomal subunit genes although it is still followed by a tuf gene (for EF-Tu). The opposite strand upstream from the EF-G coding locus revealed an open reading frame (ORF) encoding a polypeptide having 52.5% identity with an E. coli protein (the pdxJ gene product) involved in pyridoxine condensation. The Aquifex EF-G was aligned with available homologs representative of Deinococci, high G+C Gram positives, Proteobacteria, cyanobacteria, and several Archaea. Outgroup-rooted phylogenies were constructed from both the amino acid and the DNA sequences using first and second codon positions in the alignments except sites containing synonymous changes. Both datasets and alternative tree-making methods gave a consistent topology, with Aquifex and Thermotoga maritima (a hyperthermophile) as the first and the second deepest offshoots, respectively. However, the robustness of the inferred phylogenies is not impressive. The branching of Aquifex more deeply than Thermotoga and the branching of Thermotoga more deeply than the other taxa examined are given at bootstrap values between 65 and 70% in the fus-based phylogenies, while the EF-G(2)-based phylogenies do not provide a statistically significant level of support (< or = 50% bootstrap confirmation) for the emergence of Thermotoga between Aquifex and the successive offshoot (Thermus genus). At present, therefore, the placement of Aquifex at the root of the bacterial tree, albeit reproducible, can be asserted only with reservation, while the emergence of Thermotoga between the Aquificales and the Deinococci remains (statistically) indeterminate.

Amino Acid Sequence↗

PubMed2000

The ESTRO-QUALity assurance network (EQUAL).

BACKGROUND AND PURPOSE: ESTRO has set up a Quality Assurance network (EQUAL) to check the dose delivered on axis in reference and non-reference conditions for external radiotherapy. The external audits covered by the network are based on measurements made with mailed thermoluminescent dosimeters (TLD). MATERIAL AND METHODS: The TLD consist of LiF powder type DTL 937 read with a PCL 3 automatic TLD reader. The participating centres are instructed to deliver to the TLDs absorbed doses of 2 Gy calculated with the Treatment Planning System used in clinical routine. A maximum of three photon energies by participating centre have been checked with 10 on-axis points per beam. The quantities checked include the reference beam output, beam output variation with collimator opening, depth dose data and wedge transmission factor. RESULTS: During the 1998 EQUAL programme 102 centres have been checked corresponding to 235 beams (28 (60)Co beams and 207 X-ray beams). About 3% of the outputs in reference conditions show deviations outside tolerance level (>+/-5%). A similar rate of deviation is noted for the percentage depth doses. A rate of deviation (6%) has been observed for the beam output variation (open and wedged beams) and the wedge transmission factor. The analysis of the results shows that for 24 out of the 102 centres, a deviation outside tolerance level is observed at least in one point, mainly for the large and rectangular field sizes and for the wedged beams. CONCLUSIONS: The results for the EQUAL programme show the importance of a quality assurance network in Radiotherapy especially for the non reference points even if they are only located on the beam axis (In order to participate in this network, please contact EQUAL secretariat or download the attached application form ESTRO web site: Dr I.H. Ferreira or Mrs Aline Mechet, EQUAL-ESTRO, Physics Department, Institut Gustave-Roussy 39 Rue Camille Desmoulins, F-94805 Villejuif Cedex, France. e-mail:equal@igr.fr or http://www.estro.be/).

Humans↗

PubMed2026

dcHiChIP: a comprehensive Nextflow-based pipeline for multiscale analysis of chromatin architecture from HiChIP data.

MOTIVATION: Despite the growing use of HiChIP to investigate protein-directed chromatin architecture, a comprehensive and reproducible pipeline for analysing these datasets-from raw reads to multiscale 3D genome features-remains lacking. Existing tools often focus on isolated components, such as loop calling or matrix generation, but fall short in integrating structural annotation, functional enrichment, and spatial modeling within a unified framework. To address this gap, we developed dcHiChIP, a modular, scalable Nextflow-based workflow that streamlines the analysis of HiChIP data, enabling both routine processing and in-depth exploration of chromatin organization and regulatory interactions. RESULTS: dcHiChIP enables robust and reproducible analysis of HiChIP datasets across multiple scales of chromatin architecture. It accepts raw sequencing data as input and generates high-quality loop calls, domain annotations, and 3D genome models. It also performs functional annotation and motif enrichment analyses. Applied to benchmark CTCF HiChIP datasets, dcHiChIP identifies major chromatin architectural features such as TADs/CCDs, A/B compartments, and chromatin stripes, and offers efficient, end-to-end execution with support for batch processing and workflow resumability. AVAILABILITY: dcHiChIP is publicly available on GitHub at https://github.com/SFGLab/dcHiChIP, with documentation at https://sfglab.github.io/dcHiChIP/. The software version used in this study is archived at Zenodo: https://doi.org/10.5281/zenodo.22030542.

Chromatin↗

PubMed1992

Steady-state accommodation and ocular biometry in late-onset myopia.

The steady-state accommodative responses of emmetropes and late-onset myopes was measured for an array of numbers located at -1, -3 and -5 dioptres using an objective infra-red optometer. Responses were compared for passive (reading numbers) and active (adding numbers) conditions. For the passive condition, the late-onset myopes showed a significantly lower accommodative response than the emmetropic group. No significant differences were found between the two groups for the active condition. Ocular biometric characteristics were also measured in emmetropes, late-onset myopes and early-onset myopes using keratometry and ultrasonography. No significant differences in corneal curvature, anterior chamber depth and crystalline lens thickness were found between the groups. Late-onset myopes exhibited significantly deeper vitreous chambers than emmetropes, which more than accounted for the difference in refractive error between the two refractive groups. We conclude that, while significant differences exist in the accommodative responses of late-onset myopes and emmetropes, late-onset myopia is due predominantly to elongation of the vitreous chamber.

Accommodation, Ocular↗

PubMed2002

Investigation of oesophageal photoplethysmographic signals and blood oxygen saturation measurements in cardiothoracic surgery patients.

Pulse oximeter probes attached to the finger may fail to estimate blood oxygen saturation (SpO2) in patients with compromised peripheral perfusion (e.g. hypothermic cardiopulmonary bypass surgery). The measurement of SpO2 from a central organ such as the oesophagus is suggested as an alternative to overcome this problem. A reflectance oesophageal pulse oximeter probe and a processing system implemented in LabVIEW were developed. The system was evaluated in clinical measurements on 50 cardiothoracic surgery patients. Oesophageal photoplethysmographic (PPG) signals with large amplitudes and high signal-to-noise ratios were measured from various depths within the oesophagus from all the cardiothoracic patients. The oesophageal PPG amplitudes from these patients were in good agreement with previous oesophageal PPG amplitude measurements from healthy anaesthetized patients. The oesophageal pulse oximeter SpO2 results agreed well with the estimated arterial oxygen saturation (SaO2) values inferred from the oxygen tension obtained by blood gas analysis. The mean (+/- SD) of the differences between the oesophageal pulse oximeter SpO2 readings and those from blood gas analysis was 0.02 +/- 0.88%. Also, the oesophageal pulse oximeter was found to be reliable and accurate in five cases of poor peripheral perfusion when a commercial finger pulse oximeter probe failed to estimate oxygen saturation values for at least 10 min. These results suggest that the arterial blood circulation to the oesophagus is less subject to vasoconstriction and decreased PPG amplitudes than are the peripheral sites used for pulse oximetry such as the finger. It is concluded that oesophageal SPO2 monitoring may be of clinical value.

Adult↗

PubMed2003

Agreement between Scheimpflug photography and A-scan ultrasonography in anterior segment ocular measurements in children.

PURPOSE: The Scheimpflug principle, as a method of performing biometry on the anterior segment, has not been widely used in the clinical setting compared with ultrasonography. The purpose of this study was to examine the agreement in anterior chamber length and lens thickness measurements between A-scan ultrasonography and Scheimpflug photography. METHODS: A total of 252 children aged between 6 and 12 years participated in this study. All subjects had instillation of cycloplegic eye drops before measurement. Scheimpflug photography and A-scan ultrasonography were performed in this sequence on the same day. The anterior segment length on the Scheimpflug images was taken as the axial corneal thickness added to the anterior chamber depth. A-scan ultrasonography was performed by placing the probe on the corneas after topical anesthesia. Differences were obtained by subtracting the A-scan ultrasonography measurements from the Scheimpflug measurements. Data were analyzed using difference vs. mean plots. RESULTS: For anterior chamber length, the mean difference between the two methods was -0.03 +/- 0.16 mm, with 95% limits of agreement of -0.35 to +0.30 mm. However, Scheimpflug readings were greater than that of ultrasonography for smaller measurements, and the opposite was true for larger measurements. For lens thickness, the mean difference was -0.2 +/- 0.10 mm, with 95% limits of agreement of -0.40 to +0.00 mm. For the measurement of lens thickness, adding a correction factor of 0.2 mm to Scheimpflug's readings should replace that of A-scan readings reasonably well. CONCLUSIONS: The readings obtained from these two methods of biometry must be used with the knowledge of the instruments. We discuss the possible reasons for the difference in readings obtained using these two instruments.

Anterior Eye Segment↗

PubMed2001

[Drug prescription from the perspective of elderly patients].

INTRODUCTION: Although modern drugs really benefit aged patients, they also entail an increased risk to this population. Elderly people have a particular risk because of using multiple drugs with implies having more adverse reactions. This study aimed to assess elderly patients' relationship with drug prescriptions. METHODS: A descriptive study of a qualitative methods was carried out using semi-structured interviews conducted in an intentional sample of 30 elderly patients living in the urban region of Maringá, Brazil, between February 25 and March 22, 1998. Participants were selected from the Co-Participative Pharmacy Database of the Department of Pharmacy and Pharmacology of the State University of Maringá. The thematic discourse analysis technique was employed for data analysis, using three methodological entities: central idea; key-expressions; and the collective subject's discourse. RESULTS: The average consumption of drugs by this elderly population was 3.6, within a 1-8 interval. The central ideas found in the collective subjects were as follows: I'm able to take them by myself; somebody helps me; I'll take them later; I never forget; there's a need to see the physician; they have never done any harm to me; I'm used to them; sometimes I read it, sometimes I don't; I always manage to buy them; I have already stopped taking them. CONCLUSIONS: More efficient ways of assessing the willingness of elderly patients of complying with the recommended drug therapy and instituting a better drug therapy follow-up must be investigated Further studies of qualitative cut-off should be carried out to understand better the problem and analyze it in depth.

Aged↗

PubMed2003

Reliability assessment of computerized tomography scanning measurements in intracerebral hematoma.

OBJECT: As one of the aspects of the International Surgical Trial in Intracerebral Haemorrhage (STICH), prerandomization computerized tomography (CT) scans were collected. In the present study the authors determined the inter-and intraobserver variability of various parameters pertinent to CT scans obtained in patients with intracerebral hematomas (ICHs). METHODS: A protocol was devised to analyze CT scans in a uniform and systematic manner. Each observer evaluated the same set of scans twice, with a minimum 2-month interval between assessments. In addition to noting the side and the sites of involvement, the observers measured the scale present on the scan itself and the length, breadth, height, and depth of the spontaneous ICH as well as the midline shift. The intraclass correlation was very high (kappa 0.8-1) for the measurements of volume, depth, and midline shift. Good interobserver agreement (kappa 0.8-1) was demonstrated with regard to involvement of basal ganglia or thalamus, presence of intraventricular extension, and the side of the hematoma. Agreement was substantial (kappa 0.61-0.8) with regard to identifying primary involvement of particular lobes. Agreement was moderate (kappa 0.41-0.6) on the presence or absence of hydrocephalus. When comparing the first and the second sets of readings, the intraobserver agreement was good (80-100%). CONCLUSIONS: The study quantifies the degree of inter- and intraobserver agreement regarding evaluation of CT scans in patients with ICH when conducted in accordance with a set protocol.

Anthropometry↗

PubMed2001

Phylogenetic analysis of the hepatitis B virus (HBV) genotype F including Argentine isolates.

Seven human hepatitis B virus (HBV) genotypes have been described. Genotype F, indigenous to the Americas, is the most diverging group. Our in-depth analysis of the genetic distances of this genotype included ten Argentine samples. Phylogenetic analysis on the small (S) gene of the surface antigen showed four different clusters within genotype F, which were associated with a well-defined geographical origin. Even closely connected sequences sharing a common ancestor had shown some characteristics or markers indicating geographical differentiation. Nucleotide sequences and amino acids translated according to the polymerase open reading frame (P-ORF), rather than S-ORF, yielded a more discriminating analysis.

Argentina↗

PubMed1993

Variability analysis of Fo parameter in the voice of individuals with hearing disturbances.

The material of this investigation comprised a group of 18 patients with deep hypoacousis (over 70 dB) or complete deafness which, depending on the onset of the deafness, was divided into the 3 categories: congenital, early childhood to 3rd year of life, and postlingual. All of them underwent ENT, phoniatric and stroboscopy examinations; in 10, X-ray tomography of the larynx was also performed. The status of hearing ability was assessed by audiometric examinations using pure tones in air and bone conductions. The acoustic examinations comprising spectrographic and tonographic analyses were performed on an appropriate linguistic material including vowels, isolated words, sentences and reading text. The measurement of Fo was performed on isolated vowels. In order to characterise the degree and kind of periodicity disturbances the following parameters were estimated: the medium value of fundamental frequency, the range of Fo variability, the maximal change of period length from cycle to cycle, and its medium value (jitter). The results of the acoustic examinations revealed different degrees and kinds of periodicity disturbances depending on the depth of the hypoacousis and its onset.

Adult↗

PubMed1992

Radial keratotomy for the purpose of reducing glasses power in high myopia.

Anterior radial keratotomy for high myopia (over-6.25 diopter) to reduce refractive error was not able to dispense with glasses or contact lenses due to the high myopia itself. However patients could see objects well and were free of dizziness while wearing glasses of relatively reduced power. We performed anterior radial keratotomies on 83 high myopic and/or astigmatic eyes of 47 patients at Kangnam St. Mary's Hospital between May 1990 and Mar. 1991. Eight radial incisions with a diamond blade were performed and the Ruiz technique was added for astigmatism of over 2.0 diopters. The depth of incision was 90 to 95% of corneal thickness and the optical zone was 3mm in diameter. Patients were followed up on postoperative 7 days. 1 month, 3 months, 6 months, 1 year and thereafter. Uncorrected visual acuity of 20/40 or better after radial keratotomy could be obtained in 19.6% of high myopic eyes. A mean reduction of the spherical equivalent cycloplegic refraction of 5.13 diopters and a keratometric reading of 3.89 diopters after radial keratotomy were observed. About 90% of patients were satisfied with their visual outcome with reduced refractive power glasses. We recommend radial keratotomy for high myopic patients to reduce the refractive power and to help them enjoy a more comfortable life.

Adolescent↗

PubMed2000

Does head positioning influence anterior chamber depth in pseudoexfoliation syndrome?

PURPOSE: Phacodonesis can occur in pseudoexfoliation syndrome because of impaired zonular support. This study investigates whether the increased mobility of the lens influences anterior chamber depth in patients with pseudoexfoliation while assuming a prone position. METHODS: Central anterior chamber depth was measured in 39 patients with clinically apparent unilateral pseudoexfoliation and elevated intraocular pressure. Patients were placed in a face-up position for 5 minutes, at which time anterior chamber depth and axial length were measured by A scan, and intraocular pressure was measured by Tonopen (Oculab, La Jolla, CA) in both eyes. The measurements were repeated on both eyes after 5 minutes in a face-down position. RESULTS: No significant differences in intraocular pressure or axial length between the prone and supine positions were found in either eye. Anterior chamber depth in eyes with pseudoexfoliation decreased from a mean of 3.08 mm in the supine position to a mean of 2.95 mm in the prone position, whereas mean anterior chamber depth in the fellow eyes decreased from 3.01 mm to 2.97 mm. The decrease in anterior chamber depth when facing down in the eyes with pseudoexfoliation was significantly greater than in the fellow eyes. CONCLUSIONS: In patients with clinically apparent unilateral pseudoexfoliation, the lens seems to be more mobile in the affected eye. This results in a shallower anterior chamber when the head is placed in a prone position. Whether this fact might potentially lead to transient pupillary block when engaging in activities such as facing down while reading warrants further study.

Anterior Chamber↗