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Biomedical subjects

E Salas

Publications and source records attributed to E Salas.

At least 73 records · Page 4Linked to original sources
PubMed1997

Vigilant and hypervigilant decision making.

Recent studies have argued that deficient decision making under stress is due to adoption of a hypervigilant style of decision making, which has been characterized as disorganized and inefficient. However, under the conditions that characterize many real-world or naturalistic tasks, a hypervigilant pattern of decision making may be adaptive, because the decision maker does not have the luxury of implementing a more elaborate analytic procedure. This study examined the effectiveness of vigilant and hypervigilant decision-making strategies on a naturalistic task. Results indicated that participants who used a hypervigilant decision-making strategy performed better than those who used a vigilant strategy. Implications for decision making in naturalistic environments are discussed.

Arousal↗
PubMed1997

Contribution of nitric oxide to exercise-induced changes in healthy volunteers: effects of acute exercise and long-term physical training.

Endothelium plays a central role in the regulation of regional blood flow through the release of certain vasoactive substances. We conducted this study to test whether an increase in the production of nitric oxide (NO) metabolites, atrial natriuretic peptide (ANP) and plasma and intraplatelet cyclic guanosine 3':5' monophosphate (cGMP) is involved in the adaptation to chronic exercise in physically trained people and in the vasodilatation induced by acute physical exercise. We studied one group of 10 trained athletes and another group of 10 untrained people. We measured plasma levels of nitrites, nitrates and cGMP and intraplatelet levels of cGMP, as an indicator of intracellular guanylate cyclase activity, and ANP before and after a maximal treadmill test. Resting cardiac rate (CR) and systolic blood pressure (SBP) were lower in the athlete group than in the control group (73.8 +/- 3.6 vs. 92 +/- 5.9; P < 0.02 and 110 +/- 2.58 vs. 118 +/- 3.27; P < 0.02 respectively). SBP did not show differences between groups after the exercise test. Diastolic blood pressure (DBP) at rest was lower in the athlete group (71 +/- 1.79 vs. 80.5 +/- 3.53; P < 0.03) and the decrease after maximal exercise was more pronounced in this group (64 +/- 2.67 vs. 74.5 +/- 3.2; P < 0.02). Basal plasma nitrites were 4.9 +/- 0.8 in the athlete group and 1.9 +/- 0.3 in the control group (P < 0.05). After exercise, test differences between groups remained (P < 0.05). Nitrates were significantly higher in the group of athletes and did not show exercise-related changes. Plasma levels of cGMP and ANP increased in both groups after the treadmill test, with no differences between groups. Among the athletes, cGMP increased from 1.11 +/- 0.1 to 2.6 +/- 0.4 (P < 0.001), whereas in the untrained group plasma cGMP rose from 1.14 +/- 0.09 to 1.86 +/- 0.2 (P < 0.01). There was a significant correlation between the increases in plasma cGMP and the atrial natriuretic peptide in both groups (r = 0.91, P < 0.0002, for athletes; and r= 0.68, P < 0.04, for control group). The intraplatelet concentration of cGMP did not show differences between groups and did not change after exercise. In conclusion, we have found increased basal levels of plasma nitrite and nitrate in trained subjects. Exercise does not produce differences in the increments of these metabolites. Therefore, we speculate the release of nitric oxide is not augmented by exercise in trained athletes.

Adult↗
PubMed1997

Serum soluble selectins in patients undergoing cardiopulmonary bypass. Relationship with circulating blood cells and inflammation-related cytokines.

BACKGROUND: Membrane-bound selectins mediate the adhesion among leukocytes, platelets and endothelial cells, while circulating (soluble) selectins may function as competitive inhibitors of them. Open heart surgery is known to induce activation of these cells. METHODS: We studied the acute responses of soluble selectins, circulating blood cells and inflammation-related cytokines in 12 patients undergoing elective open heart surgery with cardiopulmonary bypass. Serial blood samples were withdrawn before, during and after surgery. RESULTS: Serum soluble E-selectin concentrations did not change significantly during all the perioperative period. In contrast, P-selectin decreased after the initiation of cardiopulmonary bypass and remained low until the end of surgery. L-selectin showed a similar course. A decrease in platelet count and albumin was found during the perioperative period and an increase in leukocyte count was found after cardiopulmonary bypass. Clear elevations in circulating IL (Interleukin)-6, IL-8, and IL-10 were found after the end of surgery, while IL-12 levels remained undetectable. CONCLUSIONS: While serum inflammatory cytokines clearly rise in response to open heart surgery, soluble selectins do not change (E) or decrease (P and L). Correcting for haemodilution, E-selectin rises postoperatively, but the decrease in P- and L-selectins is not explained by haemodilution.

Adult↗
PubMed1997

Changes in regional cerebral blood flow beyond the temporal lobe in unilateral temporal lobe epilepsy.

PURPOSE: Single photon emission computed tomography (SPECT) is widely used to evaluate functional abnormalities during the epileptic event. Changes in regional cerebral blood flow (rCBF) are well defined in patients with temporal lobe epilepsy (TLE) undergoing surgical resection. Nonetheless, the interpretation of ictal abnormalities in CBF beyond the temporal lobes has not been carefully addressed. METHODS: We assessed 4 patients with pathologically proven unilateral TLE who had significant ipsilateral frontal hypoperfusion in ictal studies with no other abnormalities but chronic epilepsy accounting for such findings. Patients were assessed as candidates for surgery by interictal EEG, neuropsychological studies, brain magnetic resonance imaging, scalp electrode video-EEG monitoring, and ictal SPECT. RESULTS: Characteristic hyperperfusion was evident over the temporal lobe ipsilateral to the EEG focus, with significant hypoperfusion over the frontal region in 3 patients. In patient 4, frontal hypoperfusion was not statistically significant. CONCLUSIONS: SPECT demonstrated relative rCBF changes beyond the epileptogenic zone in unilateral TLE. Our findings provide further insight into the pathophysiological changes underlying this condition.

Adult↗
PubMed1997

The role of trainee knowledge structures in aviation team environments.

The importance of having well-developed knowledge structures to enhance complex team performance has been recently indicated in the training effectiveness literature. This work tested that proposition within an aviation team training setting. Results suggested that aviation team training improved the knowledge structures of those participants who received the training. Knowledge structure data also provided information related to the training that was not available from more traditional measures of learning. Finally, results obtained from the knowledge structure measures were consistent with performance results, suggesting that knowledge structure measures are a potentially valid predictor of performance.

Aerospace Medicine↗
PubMed1997

Enhancing teamwork in complex environments through team training.

Although the importance of team training has become widely recognized, research is needed to more clearly understand what instructional strategies actually lead to enhanced teamwork and performance. This research incorporates a theoretical framework, based on the work of J.A. Cannon-Bowers, S.I. Tannenbaum, E. Salas, and C.E. Volpe (1995), to guide the systematic development of training that targeted specific team competencies (i.e., knowledge, skills, and attitudes). The theoretically designed training was delivered to 42 male aviators from an undergraduate naval aviation community. A comprehensive evaluation of this training was conducted using a multiple-measurement approach. Results provide strong support for the effectiveness of this team training in improving critical team competencies.

Aerospace Medicine↗
PubMed1996

Nitric oxide production during the hyperacute vascular rejection.

A complete understanding of the biological mechanisms that take part in the hyperacute vascular rejection is necessary to prevent its development. Nitric Oxide (NO) release by the graft could be one of those mechanisms as cytokine induction of NO synthase in reticuloendothelial cells produces NO with cytotoxic activity. We have performed 20 heterotopic pig-to-dog kidney xenotransplantations in order to determine if cytotoxic NO is released during the hyperacute rejection. Nitrites and cGMP levels were determined in plasma samples taken from the graft artery and vein until vessel thromboses. NO synthase activity was measured in pieces from renal artery and renal tissue. The results show that after discordant xenotransplantation, inducible NO synthase is activated in the transplanted organ, indicating that NO can mediate host tissue damage during the hyperacute rejection.

Acute Disease↗
PubMed1996

The effect of stress inoculation training on anxiety and performance.

Stress inoculation training is an intervention that has shown considerable promise; however, many questions arise regarding the application of this clinically based approach to more applied workplace settings. A meta-analysis was conducted to determine the overall effectiveness of stress inoculation training and to identify conditions that may moderate the effectiveness of this approach. The analysis was based on a total of 37 studies with 70 separate hypothesis tests, representing the behavior of 1,837 participants. Results indicated that stress inoculation training was an effective means for reducing performance anxiety, reducing state anxiety, and enhancing performance under stress. Furthermore, the examination of moderators such as the experience of the trainer, the type of setting in which training was implemented, and the type of trainee population revealed no significant limitations on the application of stress inoculation training to applied training environments.

Anxiety↗
PubMed1996

Effects of preparatory information on enhancing performance under stress.

Research conducted largely in medical and clinical settings suggests that receiving preparatory information prior to a stressful event can reduce negative responses to stress. Although results within this domain have been promising, little research has examined the efficacy of preparatory information on enhancing performance in a more applied task environment. This study examined the effect of preparatory information on reducing stress reactions and enhancing performance on a realistic decision-making task. Results indicated that those who received preparatory information prior to performing under high-stress conditions reported less anxiety, were more confident in their ability to perform the task, and made fewer performance errors than those who received no preparatory information.

Decision Making↗
PubMed1996

Analyzing team performance: in the eye of the beholder?

The effect of team-member experience was examined in relation to perceptions of importance of teamwork behaviors during an analysis of team performance. Importance ratings were collected from military aircrews (i.e., two-member teams) from three distinct types of aircraft. Results indicated that when assessing team behavior importance, less experienced team members weighted difficulty of performing team behaviors more heavily, whereas more experienced team members weighted time spent performing team behaviors more heavily. Implications for analyzing team performance, with respect to the process of conducting such analyses and the type of information collected, are discussed.

Aerospace Medicine↗
PubMed1996

The impact of cross-training on team functioning: an empirical investigation.

The effects of cross-training (presence vs. absence) and workload (high vs. low) on team processes, communication, and task performance were examined. Eighty male undergraduate students were randomly assigned to one of four training conditions: cross-training, low workload; cross-training, high workload; no cross-training, low workload; and no cross-training, high workload. Results indicated that cross-training was an important determinant of effective teamwork process, communication, and performance. Predicted interactions between cross-training and workload were not supported. Implications for the design and implementation of cross-training as a means to improve team functioning are discussed.

Adult↗
PubMed1996

Impairment of osteoblast growth by nitric oxide synthase inhibitors: an effect independent of nitric oxide and arginine transport inhibition.

The effect of various inhibitors of nitric oxide synthase (NOS) on three cell lines with osteoblastic phenotype was studied. N-Mono-methyl arginine (NMMA) inhibited the growth of MG63 and ROS 17/2.8 cells, and N-iminoethyl-ornithine (NIO) inhibited the growth of ROS 17/2.8. However, N-nitro-arginine (NA) and N-nitro-arginine-methyl ester (NAME) had no effect. None of the NOS inhibitors affected MC3T3 growth, in spite of blocking NO synthesis. NMMA and NIO also caused a marked decrease of arginine uptake by the three cell lines studied. These results indicate that some NOS inhibitors have antiproliferative effects which do not seem to be related to the inhibition of NOS activity or arginine uptake.

Animals↗
PubMed1995

Expression and functional role of nitric oxide synthase in osteoblast-like cells.

Nitric oxide synthases (NOS) are enzymes that produce nitric oxide (NO) from L-arginine in a reaction yielding citrulline as a coproduct. Nitric oxide modulates the activity of a wide variety of cells, but little is known about its effects on bone cells. In the present study we report that the NOS inhibitor NG-monomethyl-L-arginine (NMMA) induced a dose-dependent inhibitory effect on the proliferation of the osteoblast-like cell lines MG63 and ROS 17/2.8. The inhibitory effect was prevented by increasing L-arginine concentrations in the medium and by the NO donor sodium nitroprusside. Likewise, NMMA inhibited interleukin-6 secretion, independently of its effect on cell number. NOS expression by MG63 cells was confirmed by measuring their ability to metabolize radiolabeled L-arginine to citrulline. NOS bioactivity was detected in unstimulated cells, but was markedly increased by stimulating the cells with cytokines, lipopolysaccharide, or 1,25-dihydroxyvitamin D3. NOS activity was partially dependent upon the presence of calcium in the medium. Furthermore, constitutive-type NOS (c-NOS) and inducible-type NOS (i-NOS) mRNA expression was detected in ROS 17/2.8 cells after reverse transcription and polymerase chain reaction amplification. In conclusion, osteoblast-like cells express c-NOS and i-NOS, and NOS activity seems to play an important role in the regulation of cell proliferation and function.

Amino Acid Oxidoreductases↗
PubMed1995

Blood levels of cytokines in brain-dead patients: relationship with circulating hormones and acute-phase reactants.

We hypothesized that increased levels of blood cytokines occur in brain-dead patients, and that these cytokines are responsible for some of the endocrine and/or acute-phase reactant abnormalities found in these patients. We measured blood levels of cytokines, hormones, and acute-phase reactants in 18 brain-dead potential organ donors at the moment of establishing the legal diagnosis of brain death and compared them with levels found in a control group. Although interleukin-1 beta (IL-1 beta) and tumor necrosis factor-alpha (TNF-alpha) levels were within the normal range, interleukin-6 (IL-6) levels were clearly above the normal range in all patients (median, 1,444 pg/mL; range, 75 to 11,780). In the brain-dead group, total thyroxine (tT4), free T4 (fT4), triiodothyronine (T3), thyrotropin (TSH), dehydroepiandrosterone sulfate (DHEA-S), testosterone, albumin, Zn, and osteocalcin levels were decreased, T3 resin uptake index (T3 RUI), corticotropin (ACTH), cortisol, 11-deoxycortisol (11-DOC), 17-hydroxyprogesterone (17-OHPr), aldosterone, luteinizing hormone, and follicle-stimulating hormone levels were normal, and reverse T3 (rT3), renin, and C-reactive protein (CRP) levels were increased. Multiple regression analysis demonstrated significant interrelations between IL-6 and T4, T3, testosterone, and CRP. We also studied the evolution of some of these parameters in four patients with severe head injury who finally developed brain death. IL-6 levels on admission to the intensive care unit (ICU) were above the normal limits, as in other patients with cranial trauma, but when the patients developed brain death, there was a pronounced increase in IL-6 levels.(ABSTRACT TRUNCATED AT 250 WORDS)

Acute-Phase Proteins↗
PubMed1995

Effect of isosorbide-5-mononitrate on plasma and urine levels of cyclic GMP in relation to exercise in coronary patients compared with control subjects.

Nitric oxide (NO) and atrial natriuretic peptide (ANP) relax vascular smooth muscle increasing levels of cyclic guanosine 3':5' monophosphate (cGMP). Nitrovasodilators act as exogenous nitric oxide donors. The aim of this study was to ascertain the response of cGMP to exercise without medication and after the administration of 20 mg of isosorbide-5-mononitrate (IS-5-MN) in coronary patients (n = 8) and healthy control subjects (n = 9). A third group of 10 normal volunteers was studied to test plasma cGMP response to second exercise test without IS-5-MN administration. Plasma cGMP increased significantly in both patients (P < 0.02) and controls (P < 0.01) after the first ergometry. After IS-5-MN administration, plasma cGMP did not increase either before or after exercise. In normal volunteers without IS-5-MN plasma cGMP increased significantly after first (P < 0.004) and second (P < 0.0008) exercise test. In conclusion, plasma cGMP increases during exercise. Administration of IS-5-MN does not raise plasma cGMP and neither does performance of further exercise after its administration.

Angina Pectoris↗
PubMed1995

Enhancing transfer of training: using role-play to foster teamwork in the cockpit.

Role-plays serve a unique purpose in providing practice and feedback for aircrew team development training in the classroom. When compared with other training strategies, role-play provides targeted practice and feedback of specific behaviors at low cost, with the trade-off being the amount of fidelity it provides. This article presents guidelines for designing role-plays to elicit crew resource management (CRM) behaviors and providing feedback to trainees on their performance. Through careful design procedures, a role-play exercise can provide both targeted practice and feedback and serve a useful purpose in the overall training design of a CRM training program.

Accidents, Aviation↗