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PubMed2001

Evaluation of cognitive performance in the heat by functional brain imaging and psychometric testing.

Military operations in tropical environments have imposed a significant challenge to the Australian Defence Forces (ADF). The hot and humid conditions are known to cause debilitating effects on soldiers deployed to northern regions of Australia, with the consequence that the effectiveness and efficiency of operations are severely compromised. While the adverse effects of thermal stress on soldiers' physiological capability are well established, this has not been confirmed for cognitive performance. A select range of psychometric tests were administered and functional brain electrical activity imaging was performed to investigate the impact of thermal stress on cognitive performance. The brain electrical activity of subjects was measured while undertaking a range of cognitive tasks. Steady State Probe Topography (SSPT), a novel brain imaging technology, was employed to monitor the changes in regional brain activity and neural processing speed of subjects under thermal stress. The psychometric test batteries included the following tasks; Rey Auditory Verbal Learning Test; Inspection Time; Digit Span test; a spatial working memory task; and the AX-continuous performance task. These tasks measure a range of cognitive processes including attention, memory, verbal learning, information processing and concentration. The functional brain imaging provided topographical information, which showed changes in electrical activity in response to thermal stress during cognitive performance. These changes in brain electrical activity and neural speed induced by thermal stress may help to identify the type of cognitive functions that are likely to be impaired under operational conditions. Results indicated that subjects experienced increasing cardiovascular strain through thermally neutral to thermally straining conditions. The results from the psychometric test battery showed some promising effects given the small sample size including deficits in working memory, in information retention and in information processing. There was also marked differences in the electrical responses of the brain when subjects were thermally strained. The Steady-State Visual Evoked Potential recordings showed an increase in amplitude and a decrease in latency, suggesting an increase in the utilisation of neural resources or effort by subjects to maintain the same level of performance as under thermally neutral conditions. The data are suggestive of the high sensitivity of brain imaging techniques with high temporal resolution to identify important decrements in cognitive performance in hostile environments.

Adult↗
PubMed2001

Processing and representation of meta-data for sleep apnea diagnosis with an artificial intelligence approach.

In this article, we revise and try to resolve some of the problems inherent in questionnaire screening of sleep apnea cases and apnea diagnosis based on attributes which are relevant and reliable. We present a way of learning information about the relevance of the data, comparing this with the definition of the information by the medical expert. We generate a predictive data model using a data aggregation operator which takes relevance and reliability information about the data into account to produce a diagnosis for each case. We also introduce a grade of membership for each question response which allows the patient to indicate a level of confidence or doubt in their own judgement. The method is tested with data collected from patients in a Sleep Clinic using questionnaires specially designed for the study. Other artificial intelligence predictive modeling algorithms are also tested on the same data and their predictive accuracy compared to that of the aggregation operator.

Adult↗
PubMed1999

Structure-based design of a new class of anti-inflammatory drugs: secretory phospholipase A(2) inhibitors, SPI.

Human non-pancreatic secretory phospholipase A(2) (hnps-PLA(2)) is a group IIA enzyme that is massively over-expressed in a variety of severe inflammatory diseases. The enzyme degrades membrane phospholipids and it has been hypothesized that this activity can lead to a loss of tissue and organ integrity and function. This report overviews efforts directed toward the identification and clinical evaluation of a new class of anti-inflammatory drugs that specifically targets and inhibits the catalytic site of this hydrolytic enzyme. To achieve this goal, structure-based drug design was applied to a lead molecule identified by random high volume screening. Through an iterative process consisting of X-ray structure determination followed by inhibitor modification and testing, the lead compound was improved more than 6000-fold. Detailed information learned from earlier X-ray studies of stable substrate mimics aided this inhibitor improvement process. The optimized drug candidate, LY315920/S-5920, is currently undergoing phase II clinical evaluation. The outcome of studies such as these will define with greater clarity the pathological role of hnps-PLA(2) in human inflammatory diseases.

Acetates↗
PubMed2004

Effect of enriched environment on Ca2+ uptake via NMDA receptors into barrel cortex slices of spontaneously hypertensive rats.

Exposure to an enriched environment provides animals with informal learning opportunities and is associated with increases in brain size, cortical thickness, neuron size, dendritic branching, spine density, and number of synapses per neuron. The NMDA receptor is involved in synaptic plasticity. This study sought to determine the effect of exposure to an enriched environment on NMDA receptor function in barrel cortex slices of spontaneously hypertensive rats (SHR) and their control Wistar-Kyoto (WKY) rats. An assortment of items such as PVC pipes, metal pipes, metal boxes, metal ladders, and a polystyrene maze, were placed successively in the cages of test animals to create an enriched environment. After 2 weeks, the rats were killed. Their brains were rapidly removed, cooled in continuously oxygenated HEPES buffer (pH 7.4), and sliced in a vibratome to produce 0.35-mm thick slices. The barrel cortex was dissected from slices corresponding to 8.6-4.8 mm anterior to the interaural line and incubated with 45Ca2+ and 100 microM NMDA for 2 min. There was no difference between rats exposed to an enriched environment and rats kept in standard cages. Enrichment of environment did not alter NMDA-stimulated Ca2+ uptake into barrel cortex of SHR and WKY.

Animals↗
PubMed1999

Memory retrieval and suppression: the inhibition of situation models.

When people retrieve newly learned facts on a recognition test, they are often increasingly slowed by the number of other newly learned facts that have a concept in common with the probed fact. This is called the fan effect. Assuming that people are using situation models of the learned information, the author considers whether the inhibition of competing representations is one of the processes involved in the fan effect. Evidence was found for negative priming of related but irrelevant situation models, thus supporting the idea that the inhibition of highly related memory traces is used in long-term memory retrieval. As such, this is a form of retrieval-based inhibition.

Adult↗
PubMed1988

Contextually relevant aspects of meaning.

A series of six experiments investigated whether inferences about contextually relevant aspects of meaning were encoded into memory during reading. In all the experiments, subjects studied short paragraphs. Then, test sentences were presented that expressed relevant aspects of meaning that had not been explicitly stated in the paragraphs. For example, for a paragraph about searching for the correct color to paint a picture of a tomato, a relevant aspect of meaning would be that tomatoes are red. The test sentences were presented either immediately following the relevant paragraph or after a delay. With immediate testing, it was argued that the facilitation obtained in verification latency could result from processes occurring either when the context was read or when the test sentence was verified. With delayed testing, evidence was found to support the hypothesis that contextually relevant aspects of meaning are incorporated into the memory representation of the paragraph, but such evidence was obtained only when the retrieval environment encouraged the use of newly learned information in the decision process on the test sentence.

Cognition↗
PubMedDate not supplied

Patients' sensations after breast cancer surgery. A pilot study.

PURPOSE: The purpose of this study was to obtain information about the prevalence and characteristics of breast sensations after breast cancer surgery, the impact they had on patients, and aggravating and relieving factors. DESCRIPTION OF STUDY: Within 1 month after the date of their surgery, 132 patients with breast cancer completed an instrument rating the prevalence, severity, and level of distress of breast sensations. Information also was obtained on the impact that those sensations had on activities of daily living and factors that triggered and provided relief from sensations. RESULTS: Certain sensations remain prevalent (numb, tender), severe (burning, sharp), and distressing (cramping, painful). Overall these sensations significantly interfered with patients' activities of daily living. Certain activities (movement, position change) triggered sensations, while others (position change, medication) provided relief. CLINICAL IMPLICATIONS: Healthcare professionals can use the information learned from this pilot study to educate patients both preoperatively and postoperatively about prevalent breast sensations after surgery for breast cancer and about the types of activities that may aggravate or relieve these sensations. As patient educators and advocates, oncology professionals must continue to explore the long-term effects and treatment options to provide optimal care and support to patients who have or are likely to have post-surgical breast sensations. More studies are needed to explore long-term effects and treatment options.

Activities of Daily Living↗
PubMed2003

[Memory in the grip of emotions and stress: a necessarily harmful impact?].

While intense negative events are vividly recalled, information learned during stressful situations is poorly remembered. These differential effects of emotions and stress on memory have been attributed to the physiological manifestations generated during those affective states. Intense emotional and stressful events trigger the secretion of catecholamines and of glucocorticoids, in particular. These hormones would be modulatory agents of memory functions. In the first part of this paper, we review the specific effects emotions and stress have on memory. We then summarize the psychological and biological determinants responsible for these effects. Finally, we discuss different methodological issues that could explain the discrepancy found between the impact of emotions and stress on memory. Defining more precisely the effects emotion and stress have on memory will lead to a better comprehension of the cognitive problems that characterize patients dealing with emotional turmoil, such as patients suffering from depression or post-traumatic stress disorder.

Amygdala↗
PubMed2001

Comparative studies on the memory-enhancing actions of captopril and losartan in mice using inhibitory shock avoidance paradigm.

Renin angiotensin system (RAS) in the central nervous system participates in the processing of sensory information, learning and memory processes. Inhibitors of RAS, particularly angiotensin converting enzyme (ACE) inhibitors and angiotensin II (Ang II) receptor antagonists are reported to have potential nootropic effects in various learning and memory paradigms. The neurochemical basis underlying nootropic effect of ACE inhibitors are unclear due to wide range of substrate for this enzyme. In this study, we compared the effect of ACE inhibitor captopril and a selective AT(1)receptor antagonist losartan in a step-up shock avoidance (active avoidance) task. Captopril (5-10 mg/kg) but not losartan (5-10 mg/kg) improved learning in the second trial of the acquisition test. However, both these drugs were equally effective in enhancing retention of memory when administered prior to training. Retention enhancing effect of captopril and losartan were reversed by post-acquisition test administration of L-NAME (15 mg/kg), dizocilpine (0.05 mg/kg) and scopolamine (0.1 mg/kg). On the basis of above observations, it is concluded that decrease in endogenous Ang II activity in the brain might result in improved cognitive performance by enhancing cGMP pathways. However facilitation of acquisition only by captopril may be due to other putative mechanisms.

Angiotensin Receptor Antagonists↗
PubMed2006

Alignment effect: primary-secondary learning and cognitive styles.

The degree to which the way of learning spatial information (primary/secondary learning) and spatial cognitive style (landmark/route/survey) affect orientation specificity (alignment effect) is studied. We think that the most important factor explaining the absence of the alignment effect is the spatial cognitive style. We hypothesise that while landmark participants show an alignment effect after both primary and secondary learning, route participants show this effect only after secondary learning, and survey participants do not show it at all. Participants performed three tasks in order to distinguish their cognitive style; they were then randomly assigned to primary or secondary learning and submitted to directional judgment tasks to verify whether the alignment effect was present. The results confirm our hypothesis.

Adult↗
PubMed2006

Directly reactivated, but not indirectly reactivated, memories undergo reconsolidation in the amygdala.

Memory consolidation refers to a process by which newly learned information is made resistant to disruption. Traditionally, consolidation has been viewed as an event that occurs once in the life of a memory. However, considerable evidence now indicates that consolidated memories, when reactivated through retrieval, become labile (susceptible to disruption) again and undergo reconsolidation. Because memories are often interrelated in complex associative networks rather than stored in isolation, a key question is whether reactivation of one memory makes associated memories labile in a way that requires reconsolidation. We tested this in rats by creating interlinked associative memories using a second-order fear-conditioning task. We found that directly reactivated memories become labile, but indirectly reactivated (i.e., associated) memories do not. This suggests that memory reactivation produces content-limited rather than wholesale changes in a memory and its associations and explains why each time a memory is retrieved and updated, the entire associative structure of the memory is not grossly altered.

Amygdala↗
PubMed1998

Motives for social decision-making strategies among Finnish and Estonian adolescents [corrected].

Justifications for aggression and withdrawal were compared between Finnish and Estonian adolescents. The former had grown up in a pluralistic Western culture; the latter, in a communist Soviet culture. After receiving a questionnaire with descriptions of 2 everyday social problems, teasing and backbiting, and a list of problem-solving strategies, the participants were asked how they would justify the use of each strategy. The Estonian participants more frequently chose instrumental justifications for aggression, whereas the Finnish participants tended to report that aggressive behavior was "fun." Aggression may be perceived as more deviant in Finland than in Estonia. Among the Finnish participants, withdrawal was motivated by a desire to avoid harm; among the Estonian participants, withdrawal reflected helplessness. The Estonian participants experienced cognitive dissonance between official education and the informal information learned in families; there was also dissonance between inner speech (banned history) and the official history taught in the schools.

Adolescent↗
PubMed1995

Impaired source memory in Huntington's disease and its relation to basal ganglia atrophy.

Memory for contrived facts and the source of those facts was assessed in a group of early-stage HD patients and an age- and education-equated group of healthy control subjects. Fact recall did not differ significantly between the groups, but erroneous source attributions were more common among the HD patients. Like individuals with frontal lobe damage, HD patients have impaired memory for the source of learned information. Volume of the left caudate nucleus on MRI scans correlated with fact recall and source memory measures. These results suggest that this nucleus, or its neocortical projections, play an important role in the coding of context.

Atrophy↗
PubMed1995

Delay in diagnosis and treatment of breast cancer: implications for education.

Breast cancer is an important health concern for women in the United States. Delay in establishing diagnosis and initiating treatment may result in more advanced disease at the time of diagnosis and worse outcomes. This study evaluates 225 women from a public hospital, a university hospital cancer center, and a private practice. Times to evaluation, diagnosis, and initiation of treatment were examined. The elapsed times for the diagnosis, treatment, and combined intervals were all significantly longer for women seen in the public hospital when compared with private practice (25 and 14 days, p = 0.008, for the diagnosis interval; 15 and 10 days, p = 0.007 for the treatment interval, and 43 and 24 days, p = 0.001 for the intervals combined). Delays of three to six months or more than six months were due primarily to provider misdiagnosis and patient noncompliance in the nonprivate sites. Information learned from this study can be used to educate health care providers, patients, and systems of care to facilitate earlier diagnosis and treatment, thus reducing potentially significant delays and improving patient outcomes.

Adult↗
PubMed2004

From shame to respect: musculoskeletal pain patients' experience of a rehabilitation programme, a qualitative study.

OBJECTIVE: This study aimed to describe and analyse how participants with fibromyalgia or chronic, widespread, musculoskeletal pain, 1 year after completion, experienced a rehabilitation programme; and what knowledge and strategies they had gained. DESIGN, METHODS AND SUBJECTS: Semi-structured interviews with 16 female patients were analysed using the grounded theory method of constant comparison. RESULTS: One core category, from shame to respect, and 4 categories, developing body awareness/knowledge, setting limits, changing self-image and negative counterbalancing factors, and hopelessness and frustration over one's employment situation emerged from the data. The core category represents a process where the informants changed emotionally. Three categories were identified as important for starting and maintaining the process, one category affected the process negatively. CONCLUSION: The rehabilitation programme started the process of change, from shame to respect. The informants learned new strategies for handling their pain and other symptoms; they improved their self-image and communication in their social environment.

Adult↗
PubMed2003

Evaluation of pediatric HIV care provided in Ryan White CARE Act Title IV Women, Infants, Children, and Youth Clinics.

This evaluation examines the changing practices and outcomes of pediatric HIV care provided by the Ryan White Comprehensive AIDS Resources and Emergency (CARE) Act, Title IV grantees from 1996 through 1998--a period of rapidly changing medical practice within the United States. Using medical chart abstraction, 26 Title IV grantees reported information from the records of 525 HIV positive clients between the ages of 2 and 12. The chart abstractions covered medical care and case management provided to these clients including the number of clinical visits, use of antiretroviral therapy, use of laboratory tests such as CD4+ cell count (cells/mm3) and HIV-1 RNA viral load (copies/mL), enrollment in clinical trials, and receipt of opportunistic infection prophylaxis. Information on disease progression and hospitalization as well as client socio-demographic characteristics also is analyzed. Study results indicate that use of HIV combination therapy increased, while the occurrence of opportunistic infections and hospitalizations decreased. The increasing use of new pharmaceuticals during the study period indicates the feasibility of transferring information learned about HIV treatments from clinical trials to clinical practices that treat primarily Medicaid and pediatric populations.

Age Distribution↗
PubMed1992

The fetus in maternal hyperthyroidism.

A recent article in the New England Journal of Medicine reported the successful diagnosis and treatment of fetal goitrous hypothyroidism in a mother with Graves' disease. The fetus is being recognized as an important patient in its own right in terms of thyroid disease. The fetal thyroid system develops independently of the normal maternal thyroid axis. Presence of feedback suppression of TSH by T4 has been demonstrated in a 35-week fetus. Information learned from congenital hypothyroidism suggests that lack of fetal thyroid hormones may have a negative impact on the developing fetal brain with lack of normal myelination. It is uncertain at what gestational age the fetus and the developing central nervous system become adversely affected by thyroid hormone deficiency. Since congenital hypothyroidism is sporadic and since there is no current method for easily screening all pregnancies for hypothyroidism, the thrust in fetal diagnosis and therapy has been in those pregnancies suspected of having a hypothyroid fetus when a fetal goiter is detected by ultrasonography or in a hyperthyroid mother who may be on antithyroid therapy. Intraamniotic injections of L-thyroxine have proven successful for fetal therapy. Amniotic fluid TSH may prove useful in the diagnosis and treatment of a hypothyroid fetus. Previous studies have suggested that the period of thyroxine dependency of the fetal central nervous system is limited predominantly to the last 4-8 weeks of gestation. Fetal hyperthyroidism due to transplacental transmission of thyroid-stimulating immunoglobulins may occur in a mother with a history of hyperthyroidism due to Graves' disease.(ABSTRACT TRUNCATED AT 250 WORDS)

Female↗