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Biomedical subjects

E Bass

Publications and source records attributed to E Bass.

11 recordsLinked to original sources

Task performance with base-in and base-out prism.

The effects of base-in (BI) and base-out (BO) prism upon performance of four occupational-like tasks were measured on a group of 10 subjects who had normal binocular vision. Performance on tasks which required depth perception was significantly poorer when subjects wore prism glasses with 8 and 12 delta BI and BO, whereas 4 delta BI and BO did not significantly affect performance. The performance decrements with prism (3.0 to 6.7%) were considerably less than those induced by denial of binocularity (20 to 30%) as measured in a previous study. Thus, vergence-inducing prism does impair task performance but not as much as does the denial of binocularity. The reading and counting tasks did not require critical depth judgement and were much less affected by the prism than the needle-threading and pointers-and-straws tasks.

Adult

Binocular vs. monocular task performance.

Functional advantages of binocularity were investigated by having 13 subjects perform a group of occupational-type tasks under monocular and binocular conditions. Significant binocular advantages ranging from 29.5% (pointers in straws) to 3.7% (reading speed) were measured. Tasks with many disparity cues showed the greatest binocular advantage. This shows that patients with normal binocular vision use binocular cues, most likely stereopsis, to enhance performance. In a second experiment, three subjects with normal binocular vision underwent monocular occlusion for 5 days to investigate whether monocular skills improved to compensate for the loss of binocular vision. During that period binocular performance was consistently better than monocular performance, and both monocular and binocular performance improved, even though the subjects were only gaining monocular experience. Although the 5 day occlusion period does not simulate the long-term denial of normal binocularity that strabismics or monocular patients experience, it shows that binocular superiority remains after short-term loss of binocularity.

Functional Laterality

Cardiopulmonary arrest. Pathophysiology and neurologic complications.

Cardiopulmonary arrest is a test of the brain's tolerance to global ischemia. New insights into the pathophysiology of global ischemia have led to the potential use of early prophylactic anticonvulsants, hypothermia, barbiturate coma, glucose manipulations, calcium-blocking agents, and hemodilution. A wide spectrum of neurologic sequelae may follow global ischemia, ranging from brain death, vegetative states, and impairment of higher intellectual function to syndromes of amnesia and cortical blindness, post-anoxic myoclonus, delayed leukoencephalopathy, and spinal stroke. The distinctive features of these sequelae and their pathophysiologic aspects are discussed. Special attention is given to brain death and prognostication.

Amnesia

Neurogenic pulmonary edema.

A variety of central nervous system (CNS) insults may be complicated by the acute development of pulmonary edema. This occurrence has been termed neurogenic pulmonary edema (NPE), and experimental models have clearly shown that CNS insults may cause pulmonary edema. Unfortunately, the pathophysiologic aspects of this response are not clearly understood. Basing an approach to the development of pulmonary edema on Starling's equation leads to the conclusion that NPE is caused by changes in pulmonary endothelial permeability and/or microvascular pressures. It was previously suggested (the "blast theory") that CNS insults caused acute systemic arterial and pulmonary venous spasm and increased venous return, which would result in a severe pulmonary vascular hydrostatic insult and a secondary permeability defect. Although such hydrostatic derangements may explain certain cases of NPE, recent clinical and experimental studies have indicated that CNS disorders may cause a permeability defect without a vascular insult. The mediating factor for a permeability defect is not clear. The implications of these findings are that NPE may be caused by either permeability abnormalities or hydrostatic insults, may present clinically in a variety of ways, and may require different approaches to treatment. Our understanding of the CNS sites that might mediate NPE is not sophisticated enough, at present, to define the neural mechanisms involved in the pathogenesis of NPE.

Animals

Anticoagulation in cerebral embolism.

A case of presumed anticoagulant induced hemorrhage into infarction is presented along with a retrospective study of 110 cases of cerebral embolus. An accurate recommendation for the timing of anticoagulation following cerebral embolism hinges on balancing the risk of hemorrhage into infarction against the benefits of early treatment attributed to preventing recurrent embolism. It is felt that the present literature, concepts of pathogenesis and experimental data provide insufficient information to make absolute clinical decisions. The available evidence implies that the risk of further embolic events is three to four times that of hemorrhage into infarction, yet additional randomized prospective studies and better experimental models are needed to establish a valid treatment plan. It may be possible to distinguish separate mechanisms underlying early diffuse hemorrhage into infarction from sudden delayed massive hematoma formation.

Anticoagulants

Analgesic activity of ibuprofen (Motrin) in postoperative oral surgical pain.

The effectiveness of 400 and 800 mg. of ibuprofen was compared to that of 650 mg. of aspirin, 65 mg. of propoxyphene HCl, and placebo in 510 patients experiencing pain subsequent to oral surgical procedures. In double-blind study, patients were randomly assigned to one of five experimental groups and instructed to report the intensity of pain (complete, partial, or none) over a 3-hour period of evaluation. Ibuprofen, at both doses, was shown to be more effective for both degree and duration of relief from pain.

Adolescent

A randomized trial of team care following stroke.

A randomized controlled trial was conducted to examine the effects of interdisciplinary team care on acute hospitalized stroke patients. After obtaining baseline information on 42 stroke victims receiving conventional care in a general hospital, 130 stroke patients were stratified and randomly assigned either to Traditional or Team care. Assessments by independent evaluators permitted comparisons between Team and Traditional groups with reference to patient survival, motor performance and functional abilities. Data obtained prospectively from charts and treatment logs allowed the care process across groups to be compared. Results demonstrated that Team and Traditional patients fared similarly in survival. However there was an unexpected difference in survival depending upon sex. For motor performance, male survivors performed better with Team care and female survivors with the Traditional method. In terms of functional abilities, male patients receiving Team care again performed better than their Traditional counterparts, whereas in women there was no difference between the treatment groups.

Activities of Daily Living

Xenon-133 inhalation method for regional cerebral blood flow measurements: normal values and test-retest results.

The purpose of this investigation is to determine the normal values for regional cerebral blood flow (rCBF) as determined by the xenon inhalation method of Obrist. Normal values for all rCBF parameters were measured in 15 healthy individuals. Our data are compared with the normal data obtained by other investigators. In addition, test-retest rCBF measurements were performed to determine the reproducibility of the method. Our results show that the method is highly reproducible when carried out in serial studies over a short period of time.

Adult