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Toxicogenomics, drug discovery, and the pathologist.

The field of toxicogenomics, which currently focuses on the application of large-scale differential gene expression (DGE) data to toxicology, is starting to influence drug discovery and development in the pharmaceutical industry. Toxicological pathologists, who play key roles in the development of therapeutic agents, have much to contribute to DGE studies, especially in the experimental design and interpretation phases. The intelligent application of DGE to drug discovery can reveal the potential for both desired (therapeutic) and undesired (toxic) responses. The pathologist's understanding of anatomic, physiologic, biochemical, immune, and other underlying factors that drive mechanisms of tissue responses to noxious agents turns a bewildering array of gene expression data into focused research programs. The latter process is critical for the successful application of DGE to toxicology. Pattern recognition is a useful first step, but mechanistically based DGE interpretation is where the long-term future of these new technologies lies. Pathologists trained to carry out such interpretations will become important members of the research teams needed to successfully apply these technologies to drug discovery and safety assessment. As a pathologist using DGE, you will need to learn to read DGE data in the same way you learned to read glass slides, patiently and with a desire to learn and, later, to teach. In return, you will gain a greater depth of understanding of cell and tissue function, both in health and disease.

Animals↗

DPX: for the analysis of the protein core.

SUMMARY: In order to obtain an accurate description of the protein interior, we describe a simple and fast algorithm that measures the depth of each atom in a protein (dpx), defined as its distance (A) from the closest solvent accessible atom. The program reads a PDB file containing the atomic solvent accessibility in the B-factor field, and writes a file in the same format, where the B-factor field now contains the dpx value. Output structure files can be thus directly displayed with molecular graphics programs like RASMOL, MOLMOL, Swiss-PDB View and colored according to dpx values. AVAILABILITY: The algorithm is implemented in a standalone program written in C and its source is freely available at ftp.icgeb.trieste.it/pub/DPX or on request from the authors.

Algorithms↗

Prior knowledge and reading comprehension ability of deaf adolescents.

Fifty-one severely to profoundly deaf students (mean dB hearing loss = 89) were randomly assigned to two groups that differed by the type of probes (short or long) used to elicit prior knowledge (PK). PK scores were used to predict reading comprehension (RC), which was assessed by students' responses to three types of questions: test-explicit (TE), text-implicit (TI), and script-implicit (SI). Multiple regression models with PK scores and scores from a standardized achievement test (Stanford Achievement Test - Hearing Impaired Version, reading subtest) were also used to predict RC. The regression model showed that, for the group pretested with an in-depth, or long, probe of PK, the best predictor of RC was the ability to answer TE and SI questions. We present discussions of the observed differences in comprehension as a function of long and short knowledge probes and the use of three question types, together with implications for instruction.

Journal Article↗

[Treatment of fusional disorders in patients with brain damage].

BACKGROUND: We trained fusional convergence systematically using 3 orthoptic devices (fusion trainer, prisms, cheiroscope) in brain damaged patients with a severe deficit of convergent fusion. PATIENTS AND METHODS: 12 patients were selected, 6 with vascular cerebral lesions and 6 with traumatic brain damage. The chronicity (time since lesion) was 15.8 months (range: 2-108). Near and far visual acuity, accommodation, convergent fusional range, stereopsis (Titmus and TNO test), maximal reading duration and subjective complaints (e.g. eye strain, headache) were evaluated. To separate improvements during treatment from spontaneous recovery of function or measurement artefacts we performed repeated measurements before treatment (baseline period) during a time span of 4-6 weeks. Follow-up measurements could be performed in 9 of 9 patients 10 months after cessation of treatment. RESULTS: No improvements were seen during the baseline period. 11 of 12 patients showed a significant recovery of fusional range during training which remained stable during the 10-month follow-up period. 10 of 11 patients showed significant improvements of local stereopsis (Titmus test) and 4 of 5 patients of global stereopsis (TNO test). All patients showed a significant increase of near visual acuity of about 10% (decimal visual acuity), improved reading ability and a reduction of subjective symptoms resulting from fusional deficiency, e.g. eye strain, headache. CONCLUSIONS: These results suggest a considerable potential for recovery of oculomotor and visual functions in brain damaged patients after training.

Accommodation, Ocular↗

Glottic positioning of the endotracheal tube tip: a diagnostic dilemma.

Distal placement of the endotracheal tube tip in the glottic opening is rarely discussed in most emergency medicine, surgery, and prehospital medicine texts. We report three cases of glottic intubation recognized after the patients were thought to have been successfully intubated. Glottic positioning of the endotracheal tube tip went unrecognized initially because of the absence of air heard over the epigastrium, the presence of bilateral breath sounds, and acceptable readings by both pulse oximetry and capnography. Recognition of this complication is aided by the use of radiographic findings, inappropriate endotracheal tube depth, and the presence of inadequate ventilatory volumes. Potential complications of glottic intubation include dislodgement of the endotracheal tube, kinking of the tube, and inadequate protection of the airway.

Adult↗

Tonometry after laser in situ keratomileusis treatment.

PURPOSE: To assess the reliability of intraocular pressure measurements by Goldmann applanation tonometry versus pneumotonometry after laser in situ keratomileusis for myopia. PATIENTS AND METHODS: In this prospective study, corneal Goldmann applanation tonometry and pneumotonometry measurements were made in 118 eyes of 60 patients before and 1 and 3 months after undergoing laser in situ keratomileusis for myopia. Manifest refraction, ultrasonic corneal thickness measurements, and keratometry readings were also obtained. RESULTS: Preoperative intraocular pressure showed a good correlation between Goldmann applanation tonometry and pneumotonometry values (Pearson r = 0.71; P < 0.001). although Goldmann applanation tonometry readings were slightly higher at low intraocular pressure values and slightly lower at high intraocular pressure values. After a mean stromal ablation depth of 77.1 microm, mean intraocular pressure by Goldmann applanation tonometry decreased significantly (P < 0.001) from a preoperative value of 14.8 +/- 11.9 mm Hg to 11.9 +/- 2.1 mm Hg and 11.7 +/- 1.7 mm Hg after 1 and 3 months, respectively. Mean pre- and post-laser in situ keratomileusis measurements by pneumotonometry were similar (P = 0.8). Differences of postoperative intraocular pressure measurements by Goldmann applanation tonometry and pneumotonometry were statistically significant. After 3 months, there was a poor correlation between Goldmann applanation tonometry and pneumotonometry intraocular pressure values (Pearson r = 0.58). Postoperative intraocular pressure decrease in applanation tonometry correlated with changes in keratometry, spherical equivalent, and central corneal thickness. Regression analysis showed a decrease of 2.9 mm Hg per 70 microm reduction in central corneal thickness. CONCLUSIONS: Contact pneumotonometry measures the IOP reliably after laser in situ keratomileusis for myopia, whereas Goldmann applanation tonometry underestimates the intraocular pressure. This may be important in the treatment of any future glaucoma.

Adult↗

Detection, diagnosing, monitoring and logical treatment of occlusal caries in relation to lesion activity and severity: an in vivo examination with histological validation.

The aims of the present study were to investigate the ability of 3 experienced clinicians to detect occlusal carious lesions, assess their depth, diagnose their activity and define a logical management for each lesion. The material consisted of 35 third molars scheduled for extraction or surgical removal making it possible to validate the accuracy of the clinical recordings histologically. Examinations were carried out at baseline and after 4 months in order to monitor lesion progression. At the first visit a radiograph was taken; the number of filled surfaces was counted and the oral hygiene assessed generally and by disclosing occlusal plaque of the tooth under examination. After cleaning the occlusal surface caries was recorded in a selected investigation site using a visual ranked caries scoring system, as well as an electrical conductance recording (ECM). Apart from counting fillings and taking new radiographs the same procedure was performed at the second visit, which then was followed by extraction of the tooth. After sectioning the tooth lesion depth was recorded, and lesion activity, based on acid production, was assessed using methyl red dye. Lesion activity was also judged by means of polarized light microscopic examinations of the sections. Results showed strong relationships between the visual, ECM and radiographic assessments and both lesion depth and lesion activity. In contrast, all other parameters were poorly related to lesion activity. Changes in visual assessments and in conductance readings from first to second examination were poorly associated with lesion activity. In conclusion, clinicians are able to detect lesions, predict activity and severity and define a logical management of occlusal caries on the basis of a single examination.

Acids↗

Three-dimensional coherent transfer function for reflection confocal microscopy in the presence of refractive-index mismatch.

The three-dimensional (3-D) coherent transfer function for reflection confocal microscopy of high-numerical-aperture objectives is derived and calculated in the presence of refractive-index mismatch when a laser beam is focused into a medium of refractive index different from its immersion medium. This aberrated coherent transfer function is then used to estimate the readout efficiency of 3-D data bits recorded in a thick medium. It is shown that the readout efficiency of confocal microscopy for 3-D bit data storage is decreased with the focal depth of an objective in a recording medium. However, a high readout efficiency can be maintained if the tube length of a reading objective is linearly altered to compensate for the spherical aberration caused by the refractive-index mismatch.

Microscopy, Confocal↗

Linking lost voices: reading 'The Dead'.

The author presents an individual reading of James Joyce's short story. 'The Dead' from 'Dubliners'. Language evokes subjective responses and associations that become part of the depth of experience one finds in a book. The author describes how uses of language give the reader a sense of sharing the main character's experience. She focuses on nodal moments in the story, in which external and internal worlds intersect. Images focused on include those of seeing and touching, inside and outside, crossing gaps between worlds and the way in which these sensory events shift the character's knowledge of his internal objects. The metaphor of lost voices highlights the presence of the dead throughout the story. The main character's evolution from being in a constricted state to one of expanded self-awareness is discussed. Britton's concept of triangular space is used to describe the character's transformation at the story's conclusion.

Humans↗

Reliability of attachment level measurements using the cementoenamel junction and a plastic stent.

Repeated measurements of attachment level appear to be important assessments in periodontal clinical trials, yet the lack of reliability for this assessment creates measurement error which in turn demands increased sample sizes or reduces the power of the test. A plastic occlusal stent has been developed as a fixed reference point to assess changes in probing depths over time and thus reflect differences in attachment levels. The advantages of this system over traditional methods have not been measured. The purpose of this study was to determine intra- and interexaminer reliability for probing depths from the stent and the CEJ. Paired measurements of attachment level using the stent produced correlation coefficients for inter- and intraexaminer readings of 0.84 and 0.76, respectively. For subgingival cementoenamel (CEJ) measurements, lower coefficients of 0.71 and 0.59 were found for inter- and intraexaminer paired readings, respectively. Thus, measurements using the stent appear to be more reliable than subgingival CEJ readings.

Dental Cementum↗

Corneal topography, arcuate keratotomy, and compression sutures for astigmatism after penetrating keratoplasty.

BACKGROUND: Twenty (20) patients with post-penetrating keratoplasty (PKP) (21 eyes) and excessive corneal astigmatism were studied using corneal topography to determine placement of arcuate incisions and compression sutures for astigmatism reduction. METHODS: Keratoplasty wounds and compression sutures were placed asymmetrically based on corneal topography only. Incisions were at the donor-host junction at a depth of 500 microns. RESULTS: A 56% reduction in corneal astigmatism was accomplished with an average cylinder reduction of 5.3 D. Keratometry readings were reduced in 18 of 20 (90%) of eyes and refractive cylinder was reduced in 15 of 20 (75%) of eyes. Corrected visual acuity improved in 15 of 20 (75%) declined in 15%, and did not change in 10%. CONCLUSION: Visual acuity can be improved by manipulating the astigmatism after penetrating keratoplasty using corneal topography maps to determine placement of arcuate incisions and compression sutures.

Aged↗

A dosimetric intercomparison of electron beams in UK radiotherapy centres.

A dosimetry intercomparison has been carried out for all 52 radiotherapy centres in the UK which possess electron treatment facilities. The intercomparison was carried out on one treatment unit in each centre and for three energies across the range of available energies. The position of the depth of maximum dose for a standard field size was independently determined and a subsequent beam calibration made. The factor to convert the reading on a calibrated ionization chamber to absorbed dose in an electron beam is energy dependent, and hence to carry out an independent calibration measurement also requires the beam energy to be determined. In addition a quantitative measure of the difference in the calibration chains between the intercomparison equipment and the host department's field instrument was carried out. In order to provide a follow-up to the initial IPSM national photon intercomparison, a photon beam calibration was measured in one photon beam in each centre. For 156 electron beam measurements, a mean ratio of intercomparison measured dose to locally measured dose of 0.994 was obtained with a standard deviation of 1.8%. For the 52 photon beam measurements, a mean ratio of intercomparison measured dose to locally measured dose of 1.003 was obtained with a standard deviation of 1.0%.

Electrons↗

Postal intercomparison of absorbed dose for high energy x rays with thermoluminescence dosimeters.

This study concerns the accuracy and precision of the IAEA/WHO LiF TLD system used in intercomparison by mail of absorbed doses from 60Co gamma-radiation and 4-25 MV x rays. The system employs 160 mg LiF powder in polystyrene capsules, which are placed at 5 or 7 cm depth in water and irradiated to doses close to 200 rad (2.00 Gy). The dosimeters are mailed to the IAEA Dosimetry Laboratory and read out under conditions to minimize variatons in instrument sensitivity. The precision of the readout technique, using 3 capsules per irradiation and the readout of 5 aliquots per capsule, is characterized by 0.2% standard deviation of the resulting mean. Since random errors during the irradiation are added, the detectable systematic descrepancy in dose delivery, at the 95% confidence level, is +/- 2% for 60Co gamma and +/- 3% for high-energy x rays.

Cobalt Radioisotopes↗

The methodological journey of a grounded theorist: an interview with Denise Dignam. Interview by Lynne S. Giddings, Pamela J. Wood.

Nurses and midwives in Aotearoa/New Zealand are making a unique contribution to the development and application of various research approaches (methodologies) to nursing and midwifery practice. This is the first of a series of articles based on interviews with nursing and midwifery researchers, giving stories of their research journeys in relation to a particular methodology. The articles will give beginning researchers some real life examples of what it is like to carry out research. They are not in-depth explorations of the various methodologies. What we have attempted to capture is how real people actually use the various research methodologies we read about in textbooks and that frame the research which influences our practice. The stories are presented in interview format so that each interviewee's unique style and approach can emerge. The first researcher in our series is Denise Dignam (RGON, BA, DipSocSci) who in her PhD research is using a grounded theory approach to investigate issues related to breastfeeding.

Humans↗

Correction of attenuation in whole-body determination of Co-57 B12 absorption: concise communication.

The use of Co-57-labeled B12 for whole-body measurement of B12 uptake in humans has the advantage over Co-58 of easy commercial availability and lower cumulative radiation to the liver, but the disadvantage of significant attenuation. Methods devised to correct for the attenuation have used inaccurate early 100% counts. A method is described here that uses a liver phantom, containing a dissolved Co-57 B12 capsule, in a water tank. The ratios of upper to lower detector counts is related to total counts; it varies at different depths in the tank, and with the overall tank depth that is selected to accord with measured body habitus. The ratio of detector counts in the final patient count is used to read off the appropriate 100% total count. With this technique there is a clear discrimination between normal patients and those with pernicious anemia.

Absorption↗

Electrical impedance index in human skin: measurements after occlusion, in 5 anatomical regions and in mild irritant contact dermatitis.

The electrical impedance in 23 healthy volunteers at 2-6 different skin sites was measured with a new impedance device, which makes possible non-invasive local measurements to a controlled depth. In 11 subjects, the test sites were occluded for 24 h using empty Finn Chambers and chambers with water, physiological saline, a paper disc or 0.002% sodium lauryl sulfate (SLS). In the normal skin of 10 subjects, the electrical impedance was measured from 5 different body areas for 5 consecutive days. In 3 subjects, daily measurements for 1 month were done, both from normal skin and from skin following the application of 2% SLS. The results show that the irritation index based on electrical skin impedance gives little day-to-day variation at one and the same test site, in comparison to the variations between different test sites on the same subject and the interindividual variations observed. Significant differences in impedance values between different anatomical regions of normal skin were found. Occlusion does not affect readings taken 24 h or later after removal, but increases variance for readings taken 1 h after removal. Effects on the skin of mild irritation and its recovery phase are easily monitored with the new device. Technology based on electrical impedance, in its newly presented form, with the advantages of improved geometrical definition and depth control, can be used as an objective tool to measure skin irritation. For detection of subclinical irritant contact dermatitis, repeated readings taken over several days may be needed.

Adult↗

Depth distribution of neuronal activity related to a visual reaction time task in the monkey prefrontal cortex.

1. The depth distributions of neurons with changes in activity during a visual reaction time task were investigated in the dorsolateral prefrontal cortex of the macaque monkey, using glass micropipettes. The task was initiated by the monkey pressing a lever and consisted of an initial waiting phase (3.0-s period); a warning phase (green lamp, a variable period of 1.5-3.5 s); a lever-release GO phase (red lamp); and a final reward phase. The locations of neurons, in terms of the cortical layer, whose activities were recorded during performance of the task, were estimated histologically by marks made during the recording session. Marks were made by passing a DC current (anodal, 10-20 microA, 10-20 s) through the tip of an electrode which contained carbon fibers. Manipulator readings during the experiments and measurements of the distance of the marks from the cortical surface for 28 electrode penetrations showed a discrepancy of 2.0 +/- 5.0%, indicating that the depths at which task-related neurons were located could be estimated with errors of less than 10%. 2. Out of 162 task-related neurons recorded during 31 electrode penetrations, 53 showed changes in activity only during the warning phase (W-type; 19 phasic, 10 phasic-tonic, and 24 tonic), 37 showed changes only during the GO phase (GO-type; 4 Cue-coupled, 27 Intermediate, and 6 Movement-coupled), 34 showed changes during both the warning and GO phases (WG-type; 9 phasic, 10 phasic-tonic, and 15 tonic), and 38 showed changes during the reward phase (RE-type; 22 phasic and 16 tonic). 3. The various task-related neurons were distributed differently in different layers. Most neurons were recorded from layers III through V. In layer I, no neurons were recorded. In layer II, only a small number of neurons, with changes during the warning phase, were recorded (n = 7, 4%). One-third of the neurons were recorded in layer III (n = 51, 32%); neurons with changes during the warning phase were the most numerous (n = 24) and were significantly more numerous than neurons with changes associated with other phases of the task. One-fourth of the neurons were recorded in layer IV (n = 43, 27%); neurons with changes during the reward phase were the most numerous (n = 19), and were significantly more numerous than neurons with changes during both the warning and GO phases and also more numerous than neurons with changes during the GO phase.(ABSTRACT TRUNCATED AT 400 WORDS)

Animals↗