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Biomedical subjects

R A Bell

Publications and source records attributed to R A Bell.

At least 91 records · Page 5Linked to original sources
PubMed1993

Clinical grading of relative afferent pupillary defects.

OBJECTIVES: To assess the validity and reproducibility of quantitating relative afferent pupillary defects with the swinging flashlight test, using a 3-second pause technique, and to compare this grading system with that using neutral density filters. DESIGN: We prospectively studied patients with relative afferent pupillary defects by using the swinging flashlight test with a standardized illumination time of 3 seconds (pause time) for each eye. Each relative afferent pupillary defect was graded as follows: grade I, a weak initial constriction and greater redilatation; grade II, initial stall and greater redilatation; grade III, immediate pupillary dilatation; grade IV, immediate pupillary dilatation following prolonged illumination of the good eye for 6 seconds; grade V, immediate pupillary dilatation with no secondary constriction. The grades on the individual resident evaluations were compared with those on the group evaluations, and the grading system was compared with the neutral density filter grading system. SETTING: Neuro-ophthalmology service of an urban teaching hospital. STUDY PARTICIPANTS: A total of 119 patients. RESULTS: There was a good correlation in all grades between individual resident and group evaluations, with an overall 78% agreement. The five grades had corresponding values in neutral density filter log units: grade I, 0.4; grade II, 0.7; grade III, 1.1; grade IV, 2.0; and grade V, infinity. CONCLUSIONS: The 3-second pause technique for the swinging flashlight test is a reliable method for the detection and quantitation of relative afferent pupillary defects. The grading system can be compared with the neutral density filter grading system, and each grade has a corresponding value in log units.

Afferent Pathways↗
PubMed1993

Juror stress: identification and intervention.

The impact of stressful life events has been studied extensively in the psychiatric literature. Crisis debriefing techniques have been shown to be effective in decreasing psychiatric morbidity following exposure to these stressful situations. Stress reactions and crisis debriefing have been reported in many groups including combat veterans, survivors of natural disasters and accidents, victims of violence, and law enforcement and emergency personnel who respond to such events. One group that has not been studied extensively is jurors who are exposed to potentially disturbing material introduced as evidence in trials. Stress reactions in jurors and the value of debriefing of juries have been described by us in an earlier work. This paper describes debriefing sessions with three juries exposed to emotionally distressing material during murder trials. In comparing our experiences with these sets of jurors a number of common reactions were identified. These are discussed and a model for jury debriefing is presented.

Adaptation, Psychological↗
PubMed1992

Pattern flash visual evoked potentials in patients with homonymous hemianopia.

Visual evoked potentials from seven horizontally spaced electrodes were recorded from normal subjects and subjects with homonymous hemianopia in response to hemifield pattern flash stimulation. Stimulation produced a large early peak that was positive on the scalp contralateral to the hemifield and negative on the ipsilateral scalp. From computer fitting of the amplitudes versus electrode position, the position of the equivalent source was found to be in the contralateral hemisphere. The horizontal orientation of the dipole source was approximately tangential (parallel) to the occipital scalp surface with negative polarity toward the medial fissure. In normal subjects, visual evoked potential amplitudes at the first peak were positive on the left and negative on the right for right hemifield stimulation. Left hemifield stimulation showed the opposite results. Three patients with homonymous hemianopia showed normal visual evoked potential results from their functional hemifields and nearly flat results from their hemianopic hemifields. The normal visual evoked potentials originated in their intact cortical hemispheres.

Adult↗
PubMed1992

Neonatal alloimmune thrombocytopenia due to anti-HPA-5b (Br(a), Zav(a), Hca): the importance of third-generation platelet antibody detection techniques, a case report.

Investigation of the maternal serum in a case of suspected alloimmune neonatal thrombocytopenia by conventional, second-generation platelet serological assays (platelet radioactive antiglobulin test [PRAT], platelet suspension immunofluorescence test [PSIFT] and solid-phase adherence assay (SPAA, 'Capture-P') demonstrated only the presence of HLA class-I antibodies of limited specificities: no platelet-specific antibodies were detectable. The use of a third generation, glycoprotein capture assay (monoclonal antibody-specific immobilization of platelet antigens, MAIPA) revealed the additional presence of anti-HPA-5b with a titre of 1 in 32. Despite this relatively high titre, and the fact that it was able to induce a prolonged thrombocytopenia, this antibody was not detectable by conventional assays. In view of these findings we conclude that the use of MAIPA is essential when investigating cases of suspected alloimmune neonatal thrombocytopenia.

Abnormalities, Multiple↗
PubMed1992

Histamine potentiation by hydroxylamines: structure-activity relations; inhibition of diamine oxidase.

Hydroxylamines potentiated the responses of the canine colonic epithelium to histamine but not to other agonists such as serotonin or carbachol. We tested the hypothesis that an inhibition of histamine catabolism could explain the observed potentiation. A clear structure activity relation was defined, active compounds having the structure NH2-O-R, R being a simple uncharged aliphatic group. Active compounds delayed the disappearance of histamine from the bathing solutions and inhibited colonic diamine oxidase, an effect mimicked by standard inhibitors aminoguanidine and semicarbazide. Histamine agonists that possessed an imidazole nucleus (2- and 4-methylhistamine) were affected, whereas impromidine, 2 pyridylethylamine, and dimaprit were not. Agonist specificity combined with the enzyme data suggest an inhibition of histamine catabolism as a possible mechanism for the potentiating effects observed.

Amine Oxidase (Copper-Containing)↗
PubMed1991

Crisis debriefing of a jury after a murder trial.

The importance of crisis debriefing for those involved in major accidents, violent crimes, and natural disasters has been demonstrated. Similar debriefing may be warranted for jurors exposed to disturbing material in criminal cases. The authors describe a debriefing session for jurors after the murder trial of a man whose truck had collided with a school bus, killing 27 people. The graphic evidence of the accident, the high levels of emotion of the survivors and the victims' relatives, and the intense community and national attention to the trial placed the jurors under considerable stress. The debriefing enabled the jurors to express their feelings of anger, guilt, and frustration and to begin to accept their role in the event.

Crisis Intervention↗
PubMed1991

Space travel shortens diapause in gypsy moth eggs.

Field-collected and laboratory-reared gypsy moth eggs were exposed to microgravity, cosmic radiation, sub-freezing temperatures, unusual vibrations, and other extraterrestrial phenomena while they were sealed for 6 days, in January, in a Get-Away-Special (GAS) canister in the open bay of a NASA earth-orbiting spacecraft, the Columbia. Insects were not exposed to light after preparation for and during space flight. Under field conditions, out-of-doors, the eggs should have hatched in April, after 3-4 months of chilling temperatures and should not have hatched after the 6 days of chilling to -11 degrees C during flight in the Columbia spacecraft. However by April 1, more than 4000 larvae had hatched from eggs that had travelled in space, as opposed to approximately 350 from a similar number of control, earthbound eggs. These results indicate that the period of a circannual rhythm in field- and lab-reared insects had been shortened, presumably as result of exposure to microgravity, other factors associated with space flight, and/or conditions of outer space. These results suggest that it may be possible to develop methods for rearing the gypsy moth year round, without the necessity of three months chilling interspersed in the development process. This, in turn, would facilitate production of large numbers of insects for sterile male release or for use as a rearing medium for parasites, predators and pathogens of the gypsy moth.

Animals↗
PubMed1991

Homonymous hemianopic field defects and driving in Canada.

Significant functional impairment due to loss of visual field may seriously compromise the safe operation of a motor vehicle. The variable degree of recovery from homonymous hemianopic field defects and the lack of standardized provincial licensing guidelines on visual field defects further compound the difficulty in managing such patients. We reviewed the records of 60 patients with homonymous hemianopic field defects who were followed for an average of 27 months. The ability of the patients to meet the current provincial licensing standards was evaluated on presentation and over the follow-up period. On presentation 34 patients (57%) did not meet the minimum field requirements for an unrestricted license in any province or territory. At the most recent follow-up visit 20 patients (33%) had functional improvement, as measured by their ability to meet the requirements of more regions than they could initially. Four patients (7%) became functionally worse. Patients with homonymous hemianopic field defects should be followed for at least 2 years. The physician should inform the patient that a significant visual disability exists and advise him or her to cease driving when minimum standards are not met.

Adolescent↗
PubMed1990

Conversion of 3-dehydroecdysone by a ketoreductase in post-diapause, pre-hatch eggs of the gypsy moth Lymantria dispar.

The prothoracic glands (PGs) of Lymantria dispar (day-5 female, last-stage larvae) produce both ecdysone and an ecdysteroid which has the same retention time on reverse-phase liquid chromatography (RPLC) as a known standard of 3-dehydroecdysone. The latter ecdysteroid can be converted by a heat-labile factor in extracts of post-diapause, pre-hatch L. dispar eggs to an ecdysteroid which has the same retention time on RPLC as ecdysone. Purified 3-dehydroecdysone, similarly treated with egg extract, also gives the same retention time on RPLC as ecdysone. Taken together, these data suggest that, like Manduca sexta, a major product of the PGs in L. dispar is 3-dehydroecdysone. Furthermore, these data suggest that L. dispar eggs, which contain mature embryos, possess ecdysteroid ketoreductase activity capable of converting 3-dehydroecdysone to ecdysone. This is the first report of ecdysteroid ketoreductase activity in embryonated eggs.

3-Hydroxysteroid Dehydrogenases↗
PubMed1990

1H NMR assignments and conformational analysis of the oligoribonucleotides CA, CAU, CAUG, ACAUG, and UCAUG: observation of pyrimidine H5-H1' long-range scalar couplings.

Conformational analysis and 1H NMR spectral assignments have been carried out using COSY and RELAY methods for a series of related oligoribonucleotides including two pentamers with 5'-dangling bases. Intraresidue long-range five bond scalar coupling was observed between pyrimidine H5 and H1' protons in the COSY-45 spectra and this feature was useful for both assignment purposes and conformational analysis. The ribose ring conformations were predominantly C3'-endo with the C2'-endo population increasing at the 3'-terminus. The 5'-dangling bases were not stacked efficiently, exhibiting lower % C3'-endo values than their 3'-nearest neighbors. Backbone torsion angle population. beta t, gamma +, epsilon t, were determined using 1H-1H, 1H-31P, and 13C-31P coupling constants. From beta t and gamma + populations the U3-G4 step in CAUG was found to be less efficiently stacked than the C1-A2 and A2-U3 steps. This observation in solution is consistent with the fiber diffraction A-RNA model (S. Arnott, D.W.L. Hukins, S.D. Dover, W. Fuller and A.R. Hodgson, J. Mol. Biol. 81, 107-122, 1973) which also predicts poor stacking in a U-G dinucleotide. The epsilon t populations were greater than 65% for all C3'-O3' bonds and consistent with a right-handed A-RNA helix.

Base Sequence↗
PubMed1990

Attitudes of medical school faculty and students toward acquired immunodeficiency syndrome.

Attitudes of faculty and students will influence the success of educational programs to address acquired immunodeficiency syndrome (AIDS). In 1988-89, 170 medical school faculty and 227 students completed needs assessment questionnaires at the University of Louisville, and the results were compared to assess the respondents' attitudes about AIDS. Both the faculty and the students were found to be fearful of infection, had strong negative attitudes toward AIDS patients, and had low levels of confidence in the current knowledge about AIDS. Both cognitive and affective training strategies are recommended to help learners distinguish unwarranted from warranted fears of infection and to increase their empathy for patients with AIDS.

Acquired Immunodeficiency Syndrome↗
PubMed1990

Cofactors in the commission of violent crimes: a self-psychology examination.

In many violent crimes a cofactor seems to play a part in the emergence of the violent act. The individuals involved in these cases appear to suffer from significant self pathology. The violent behaviors represent disintegration products of the self designed to maintain cohesion in the face of self-fragmentation. Without the presence of selfobjects, the violent act is less likely to occur. Thus, self psychology provides valuable insights into the commission of certain violent crimes.

Borderline Personality Disorder↗
PubMed1990

Outcomes of AIDS training for supervisory and nonsupervisory personnel in the workplace.

Dealing with AIDS in the workplace is complicated by a variety of complex issues. One factor influencing how AIDS is dealt with is the difference in knowledge and attitudes between supervisory and nonsupervisory personnel. We surveyed 3834 supervisory and nonsupervisory personnel from a number of businesses and corporations in the Louisville metropolitan area. The differences found in this study suggest strategies for training to address the problem of AIDS in the workplace.

Acquired Immunodeficiency Syndrome↗
PubMed1990

Evaluating the outcomes of AIDS education.

AIDS provides a unique challenge to health educators, requiring continuous evaluation and modification of educational strategies. Pretest and posttest questionnaires were thus used to assess the outcomes of AIDS training sessions. Results show that hour-long sessions result in knowledge acquisition and increased confidence among a demographically representative sample of 3,966 U.S. trainees. Results also reveal the dynamic nature of a training session, with some trainees exhibiting learning and others retaining either correct or incorrect responses or changing from one incorrect to another incorrect answer. Content areas that showed the most learning were sharing a glass or food with and being sneezed on by someone infected with the human immunodeficiency virus (HIV). Areas resistant to learning included the possibility of transmission from receiving blood transfusions, eating in a restaurant where a cook is infected, being bitten by a mosquito, giving mouth-to-mouth resuscitation, and providing first aid to someone infected. Repeat training sessions that take into account affective dimensions as well as the diverse needs of adult learners are recommended.

Acquired Immunodeficiency Syndrome↗
PubMed1989

Selected indices of micronutrient status in adult patients with sickle cell anemia (SCA).

In 24 adults with hemoglobin SS followed at the Duke University Comprehensive Sickle Cell Center, we have studied the following nutritional parameters: reduced ascorbic acid; dehydroascorbic acid; alpha and beta carotenes; cryptoxanthin; and alpha and gamma tocopherols in whole blood, washed red blood cells, plasma, or serum. In the same population we also examined reduced glutathione (GSH) and oxidized glutathione (GSSG). Fifteen of these 24 patients also were interviewed for usual dietary intakes using a 28-day dietary history. Data obtained from patients with hemoglobin SS, sickle cell anemia (SCA) were compared to those found for seven healthy normal black adults of similar age. Plasma alpha tocopherol levels were significantly lower in SCA individuals than those of the controls (P less than 0.004). Alpha and gamma tocopherol levels in sickle RBCs were significantly higher than those from RBC suspensions of control subjects (P less than 0.007, and P less than 0.001, respectively). All serum values for carotenoids examined, specifically, beta carotene, alpha carotene, and cryptoxanthin were also markedly depressed when compared to those of healthy controls (P less than 0.001, P less than 0.002, and P less than 0.001, respectively). No other statistically significant differences were found between the two groups for any of the remaining variables, including dietary estimates. Dietary analyses suggest that dietary intakes of SCA individuals exceeded the recommended daily allowances (RDA) of all macro- and micronutrients measured, and intakes of most nutrients exceeded those of black controls interviewed. These results suggest that in individuals with SCA, several micronutrients vital to maintaining reducing capacity are present in diminished quantities in plasma/serum. These anomalies exist in SCA patients even though their intake of these micronutrients are similar to those of healthy black men and women.

Adult↗
PubMed1989

Acoustic analysis of gradient-coil noise in MR imaging.

A survey was conducted of acoustic noise levels in magnetic resonance (MR) imaging systems. Static magnetic flux and radio-frequency pulses did not affect the function of shielded sound-pressure detection equipment. Noise levels were measured at bore isocenter during a variety of imaging sequences in six MR imaging systems with magnetic fields of 0.35-1.5 T. Measured noise ranged from 82 to 93 dB on the A-weighted scale and from 84 to 103 dB on the linear scale. Noise levels increased during sequences employing thinner section thickness and shorter repetition and echo times and were independent of field strength. Gradient-coil noise in MR imaging is an annoyance but is well within safety guidelines.

Humans↗