Acute effects of ketamine on memory systems and psychotic symptoms in healthy volunteers.
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N-methyl-D-aspartate (NMDA) receptor antagonists have been demonstrated to induce schizophrenia-like symptoms and cognitive impairment in humans. The NMDA receptor has been strongly implicated in memory, but research to date on the effects of NMDA antagonists has examined only some aspects of human memory functions. This study used a double-blind, placebo-controlled, independent groups design with 54 healthy volunteers to examine the effects of infusions of two doses (0.4, 0.8 mg/kg) of the NMDA antagonist ketamine upon the five human memory systems, aspects of executive functioning and schizophrenia-like and dissociative symptoms. Ketamine produced a dose-dependent impairment to episodic and working memory and a slowing of semantic processing. Ketamine also impaired recognition memory and procedural learning. Attention, perceptual priming and executive functioning were not affected following the drug. In addition, ketamine induced schizophrenia-like and dissociative symptoms, which were not correlated with the cognitive measures. These data suggest that, in humans, ketamine produces a selective pattern of impairments to working, episodic, and procedural memory but not to perceptual priming, attention or aspects of executive functioning. (+info)
Ethical dilemmas in malaria drug and vaccine trials: a bioethical perspective.
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Malaria is a disease of developing countries whose local health services do not have the time, resources or personnel to mount studies of drugs or vaccines without the collaboration and technology of western investigators. This investigative collaboration requires a unique bridging of cultural differences with respect to human investigation. The following debate, sponsored by The Institute of Medicine and The American Society of Tropical Medicine and Hygiene, raises questions concerning the conduct of trans-cultural clinical malaria research. Specific questions are raised about the difficulties of informed consent in different cultural settings and whether there is any role for community involvement. Discussants debate whether drug and vaccine trials not approved in an industrialised country are ever defensible if performed in a third-world setting. Potential conflicting priorities between investigators are discussed and ideas regarding conflict resolution are offered. (+info)
Quality of life philosophy III. Towards a new biology: understanding the biological connection between quality of life, disease, and healing.
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This paper addresses (in a philosophical way) the complex and enigmatic interface between matter, life, and consciousness in modern medical science. The problem today in understanding living matter is not at the molecular level, but at the macro level where all molecular activities in the individual cell are coordinated, and especially at a higher level, where the activities of all the organism"s cells are coordinated. Although we understand very much of the body"s chemistry, we have only just started to get the gist of the tremendous organization of living matter. We are just beginning to acknowledge the enormous flow of information that is needed to make everything function in a healthy organism, including consciousness, where every cell does exactly what it has to do to make the organs function. A concept that seems to be able to bridge the scientifically very different domains of matter, life, and consciousness seems to be "biological information". If a cell is seen as a liquid crystal in which the cell"s molecules constantly connect in firm mutual relationships only to dissolve again and become fluid and free, whenever the cell needs it, the backbone of the cell seems to be the information that organizes the cell. For example, in cell motion a cell is able to crawl with the help of a skeleton of fibers that can be created guided by biological information, whenever the cell needs the solidity provided by the fibers. The moment it has finished crawling or intends to crawl in another direction, these fibers will dissolve again. The fibers are made of millions of molecules that connect in an arranged pattern, and they dissolve when these molecules again let go of each other. How the cell precisely regulates such processes is today a complete mystery. How cells cocreate consciousness is also an enigma. All we can do is describe the cell and the organisms arising from its cells as filled with energy and information as well as an unbeatable ability to organize itself way down to the molecular level, where apparently the cell is in control of almost every single molecule. Our understanding today of how the information is stored and how it flows through living matter is still very limited. The source of the qualities (the qualia) characterizing the human being as a whole--like joy, love, motivation, consciousness, free will, wisdom, intuitive competence--is still practically unknown and scientifically unexplained, more than 50 years after science has turned itself towards these fundamental problems. We believe that we need a radically new biology and medicine to give the scientific explanations of the structure, dynamics, and quality of life, and of its consciousness. (+info)
A randomized comparison of patients' understanding of number needed to treat and other common risk reduction formats.
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BACKGROUND: Commentators have suggested that patients may understand quantitative information about treatment benefits better when they are presented as numbers needed to treat (NNT) rather than as absolute or relative risk reductions. OBJECTIVE: To determine whether NNT helps patients interpret treatment benefits better than absolute risk reduction (ARR), relative risk reduction (RRR), or a combination of all three of these risk reduction presentations (COMBO). DESIGN: Randomized cross-sectional survey. SETTING: University internal medicine clinic. PATIENTS: Three hundred fifty-seven men and women, ages 50 to 80, who presented for health care. INTERVENTIONS: Subjects were given written information about the baseline risk of a hypothetical "disease Y" and were asked (1) to compare the benefits of two drug treatments for disease Y, stating which provided more benefit; and (2) to calculate the effect of one of those drug treatments on a given baseline risk of disease. Risk information was presented to each subject in one of four randomly allocated risk formats: NNT, ARR, RRR, or COMBO. MAIN RESULTS: When asked to state which of two treatments provided more benefit, subjects who received the RRR format responded correctly most often (60% correct vs 43% for COMBO, 42% for ARR, and 30% for NNT, P =.001). Most subjects were unable to calculate the effect of drug treatment on the given baseline risk of disease, although subjects receiving the RRR and ARR formats responded correctly more often (21% and 17% compared to 7% for COMBO and 6% for NNT, P =.004). CONCLUSION: Patients are best able to interpret the benefits of treatment when they are presented in an RRR format with a given baseline risk of disease. ARR also is easily interpreted. NNT is often misinterpreted by patients and should not be used alone to communicate risk to patients. (+info)
Agrammatic comprehension of simple active sentences with moved constituents: Hebrew OSV and OVS structures.
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This study examines agrammatic comprehension of object-subject-verb (OSV) and object-verb-subject (OVS) structures in Hebrew. These structures are syntactically identical to the basic order subject-verb-object (SVO) sentence except for the movement of the object to the beginning of the sentence, and thus enable empirical examination of syntactic movement in agrammatic comprehension. Seven individuals with agrammatism, 7 individuals with conduction aphasia, and 7 individuals without language impairment, all native speakers of Hebrew, performed a sentence-picture matching task. The task compared OSV and OVS sentences to SVO sentences and to subject and object relatives. Individuals with agrammatism performed more poorly than those in either of the other groups. Their comprehension of SVO sentences was significantly above chance, but comprehension of OSV and OVS sentences was at chance and was poorer than comprehension of SVO sentences. These results show that agrammatic comprehension of structures that involve movement of a noun phrase is impaired even when the structure is a simple active sentence, in line with the Trace Deletion Hypothesis (TDH; Y. Grodzinsky, 1990, 1995a, 2000). A modification is suggested to accommodate the TDH with the VP Internal Subject Hypothesis, according to which individuals with agrammatism use an "Avoid Movement" strategy in comprehension. (+info)
Trainee anaesthetists understand their work in different ways: implications for specialist education.
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BACKGROUND: Traditionally, programmes for specialist education in anaesthesia and intensive care have been based on lists of attributes such as skills and knowledge. However, modern research in the science of teaching has shown that competence development is linked to changes in the way professionals understand their work. The aim of this study was to define the different ways in which trainee anaesthetists understand their work. METHODS: Nineteen Swedish trainee anaesthetists were interviewed. The interviews sought the answers to three open-ended questions. (i). When do you feel you have been successful in your work? (ii). What is difficult or what hinders you in your work? (iii). What is the core of your anaesthesia work? Transcripts of the interviews were analysed by a phenomenographic approach, a research method aiming to determine the various ways a group of people understand a phenomenon. RESULTS: Six ways of understanding their work were defined: giving anaesthesia according to a standard plan; taking responsibility for the patient's vital functions; minimizing the patient's suffering and making them feel safe; giving service to specialist doctors to facilitate their care of patients; organizing and leading the operating theatre and team; and developing one's own competence, using the experience gained from every new patient for learning. CONCLUSIONS: Trainee anaesthetists understand their work in different ways. The trainee's understanding affects both his/her way of performing work tasks and how he/she develops new competences. A major task for teachers of anaesthesia is to create learning situations whereby trainees can focus on new aspects of their professional work and thus develop new ways of understanding it. (+info)
Randomisation in trials: do potential trial participants understand it and find it acceptable?
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OBJECTIVE: To examine lay persons' ability to identify methods of random allocation and their acceptability of using methods of random allocation in a clinical trial context. DESIGN: Leaflets containing hypothetical medical, non-medical, and clinical trial scenarios involving random allocation, using material from guidelines for trial information leaflets. SETTING AND PARTICIPANTS: Adults attending further education colleges (n = 130), covering a wide range of ages, occupations, and levels of education. MAIN MEASURES: Judgements of whether each of five methods of allocation to two groups was random in a medical or non-medical scenario. Judgements of whether these allocation methods were acceptable in a randomised clinical trial scenario, with or without a scientific justification for randomisation. RESULTS: The majority of our group of participants judged correctly that allowing people their preference was not random, and that the following were random: using a computer with no information about the individual (recommended wording for MREC trial leaflets), tossing a coin, drawing a name out of a hat. Judgements were split over allocating people in turn (not a random allocation method but shares features with randomisation). Judgements were no different in medical and non-medical scenarios. Few of the correctly identified random methods were judged to be acceptable in a clinical trial scenario. Inclusion of a scientific justification for randomising significantly increased the acceptability of only one random method: allocation by computer. CONCLUSIONS: Current UK guidelines' recommended description of random allocation by computer seems warranted. However, while potential trial participants may understand what random allocation means, they may find it unacceptable unless offered an acceptable justification for its use. (+info)
Integration of word meaning and world knowledge in language comprehension.
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Although the sentences that we hear or read have meaning, this does not necessarily mean that they are also true. Relatively little is known about the critical brain structures for, and the relative time course of, establishing the meaning and truth of linguistic expressions. We present electroencephalogram data that show the rapid parallel integration of both semantic and world knowledge during the interpretation of a sentence. Data from functional magnetic resonance imaging revealed that the left inferior prefrontal cortex is involved in the integration of both meaning and world knowledge. Finally, oscillatory brain responses indicate that the brain keeps a record of what makes a sentence hard to interpret. (+info)