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Results for “Paradigm shift”

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At least 703 records · Page 39Linked to original sources

PubMed2000

Effects of the non-competitive NMDA-receptor antagonist memantine on morphine- and cocaine-induced potentiation of lateral hypothalamic brain stimulation reward.

RATIONALE: NMDA-receptor antagonists may be of potential therapeutic use in several states of disease. It has been reported that drugs like MK-801 can potentiate the rewarding effects of other drugs, which may complicate the therapeutic use of this class of drugs. However, since MK-801 appears to be an "atypical" drug in several respects, other NMDA-receptor antagonists may not share this effect of MK-801. OBJECTIVES: We tested the effects of memantine, a clinically used NMDA-receptor antagonist, in a paradigm that has previously shown the reward-potentiating effects of MK-801 to see if this drug would yield qualitatively comparable results. METHODS: The effects of memantine on morphine- and cocaine-induced potentiation of brain stimulation reward were examined, using the rate-free curve-shift paradigm. RESULTS: Low doses of morphine (2.5 mg/kg) and cocaine (5 mg/kg) produced moderate decreases in the reward threshold frequency reflected in moderate leftward shifts of the function relating response rate to stimulation frequency. These effects were not altered by co-administration of an intermediate dose of memantine (5 mg/kg), but maximum response rate was significantly increased by these drug combinations. Higher doses of morphine (7.5 mg/kg) and cocaine (10 mg/kg) had stronger effects on the rate-frequency function and reward threshold. These effects were enhanced by co-administration of a high dose of memantine (10 mg/kg), while the effects on maximum response rate were less pronounced. CONCLUSIONS: These results demonstrate that fairly high doses of memantine and morphine or cocaine have to be combined in order to observe an enhancement of the latter drugs' potentiation of brain stimulation reward. In this respect, memantine differs markedly from MK-801, another non-competitive NMDA-receptor antagonist which has been shown to interact with morphine and cocaine at very low doses.

Analgesics, Opioid↗

PubMed2006

Developing sustainability: a new metaphor for progress.

In this paper, we propose a new model for development, one that transcends the North-South dichotomy and goes beyond a narrow conception of development as an economic process. This model requires a paradigm shift toward a new metaphor that develops sustainability, rather than sustains development. We conclude by defending a 'report card on development' as a means for evaluating how countries perform within this new paradigm.

Commerce↗

PubMed1999

Organizational change towards the empowerment-community integration paradigm in community mental health.

As a part of a larger study of change towards the values of an empowerment-community integration paradigm in community mental health, we examined changes in 3 mental health organizations in 1 community. Using qualitative methods, we focused on: (a) change pathways, (b) organizational change outcomes, and (c) the factors which helped and hindered change outcomes. We found evidence of a paradigm shift in the values and related practices within the organizations. Our results and themes are discussed and aimed at understanding and integrating knowledge about organizational change and the empowerment-community integration paradigm in community mental health.

Community Mental Health Services↗

PubMed2006

Early mobilization after aortic valve surgery.

In recent years, the focus in peri-operative care of cardiac patients has shifted from trying to create a stress-free environment to hasten the recovery of patients by providing early extubation, early mobilization, and enteral nutrition. Fast-track cardiac surgery has therefore made a paradigm shift in postoperative care. However, evidence on the safety of early postoperative mobilization in high-risk groups like aortic valve replacement surgery is lacking. Physiological evidence from controlled studies in patients undergoing aortic valve replacement (AVR) showed that heart rate increases and stroke volume falls with maintenance of cardiac output. However, the increase of 50% to 60% of oxygen consumption during mobilization is covered by increased oxygen extraction, resulting in marked mixed venous oxygen desaturation. These physiological changes during postoperative mobilization were also seen in CABG patients. The mobilization pattern was also maintained on the second day after surgery. No serious side effects were observed in the controlled trials of mobilization of AVR patients after cardiac surgery. Over a 13-year period, we have mobilized more than 1200 AVR patients. No serious situations have occurred during or in direct connection to mobilization.

Aortic Valve Insufficiency↗

PubMed2005

Porous scaffold design for tissue engineering.

A paradigm shift is taking place in medicine from using synthetic implants and tissue grafts to a tissue engineering approach that uses degradable porous material scaffolds integrated with biological cells or molecules to regenerate tissues. This new paradigm requires scaffolds that balance temporary mechanical function with mass transport to aid biological delivery and tissue regeneration. Little is known quantitatively about this balance as early scaffolds were not fabricated with precise porous architecture. Recent advances in both computational topology design (CTD) and solid free-form fabrication (SFF) have made it possible to create scaffolds with controlled architecture. This paper reviews the integration of CTD with SFF to build designer tissue-engineering scaffolds. It also details the mechanical properties and tissue regeneration achieved using designer scaffolds. Finally, future directions are suggested for using designer scaffolds with in vivo experimentation to optimize tissue-engineering treatments, and coupling designer scaffolds with cell printing to create designer material/biofactor hybrids.

Animals↗

PubMed2003

Embracing the new paradigm of assessment in residency training: an assessment programme for first-year residency training in anaesthesiology.

Assessment of clinical competence is facing a paradigm shift in more than one sense. The shift relates to test content, which increasingly covers a broader spectrum of competences than mere medical expertise, and to test methods, with an increasing focus on testing performance in realistic settings. Also there is a shift in the concept of assessment in that instruction and assessment are no longer seen as being separate in time and purpose, but as integral parts of the learning process. The nature of the new paradigm for assessment is well described but the challenge to programme directors is to specify the evaluation situations and develop appropriate methods. This paper describes the intrinsic rational validation process in outlining an assessment programme for first-year anaesthesiology residency training according to the new paradigm. The applicability to other residency programmes and higher-level training in anaesthesiology is discussed.

Anesthesiology↗

PubMed1990

The discursive formation of the body in the history of medicine.

The principal argument of the present paper is that the human body is as much a reflective formation of multiple discourses as it is an effect of natural and environmental processes. This paper examines the implications of this argument, and suggests that recognizing the body in this light can be illuminating, not only for our conception of the body, but also for our understanding of medicine. Since medicine is itself a discursive formation, a science with both a history, and a future, it is argued that much can be learned by reflecting on the progression of models, or "paradigm-shifts,", in terms of which modern medicine has articulated the human body that figures at the heart of its discourse. Four historical periods of medicine will be considered, each one governed by its own distinctive paradigm. It is argued, finally, that, with the emergence of behavioural medicine, and, more particularly, psychoneuroimmunology, a new discursive formation in medicine, one can see a new conceptualization of the human body beginning to take shape; and that this new figure of the body makes it possible for the very first time to conceive the construction of testable hypotheses regarding correlations between the objective body of science and the phenomenological body of experienced meaning.

Animals↗

PubMedDate not supplied

[Electrophysiology of executive functions].

INTRODUCTION: In neuropsychology, executive functions have been defined as those that coordinate the flow of information processing in the brain. In the last decade its study has undergone an important development, partly due to the use of functional neuroimaging. DEVELOPMENT: Electrophysiological techniques have also provided a link between two specific components of the event related brain potential (ERP) and certain control and monitoring processes, as those described in theoretical frameworks of executive functioning (i.e., Norman & Shallice). On the one hand, attentional set shifting paradigms allow us to relate the anteriorly (P3a; latency 300-350 ms) and posteriorly (P3b; latency 450-600 ms) distributed components of the so called 'novelty P3', with a more general mechanism of attentional set shifting that could account for both stimulus and task novelty. On the other hand, 'error related negativity' (ERN or En) has shown its sensitivity to action monitoring (i.e., error detection and error correction processes), during the execution of response selection RT tasks. CONCLUSIONS: The comprehension of these two executive processes represents critical aspects in our understanding of brain function, and has direct applications to the design of both theoretical models and assessment and rehabilitation programs for patients with dysexecutive disorders.

Cognition↗

PubMed1999

Facilitatory effect of unilateral lesion of the ventral tegmental area on locomotor response to stimulation of the contralateral ventral tegmental area: involvement of GABAergic transmission.

It was found previously that in the rat, unilateral electrolytic lesion of the ventral tegmental area (VTA) facilitated feeding induced by electrical stimulation of the homologous VTA tissue in the contralateral hemisphere. In the present work, VTA stimulation-induced locomotor response was tested in male Wistar rats using a latency to move/stimulation frequency curve shift paradigm in order to check for functional generality of the "contralateral facilitation effect" and also with the aim of elaborating an easy and reliable behavioral model to study this phenomenon. In a further step, the hypothesis was tested that enhancement of function of the intact VTA results from elimination of tonic GABAergic influence derived normally from the lesioned VTA. GABA(A) (bicuculline, doses 0, 0.5 and 5.0 ng) and GABA(B) (phaclofen, doses 0, 500 and 1000 ng) receptors antagonists, and for comparison, a GABA(A) receptor agonist (muscimol, doses 0, 12.5, 25. 0 and 50.0 ng), were injected unilaterally to VTA and their effect on locomotor response elicited by electrical stimulation of the contralateral VTA was tested in a latency/frequency paradigm. It was found that similar to feeding, locomotor response evoked by unilateral electrical stimulation of the VTA was facilitated after contralateral VTA lesion which manifested as a decrease of the locomotion threshold and a leftward shift of the function relating latency to move to stimulation frequency. The effect was immediate, long-lasting and specific to the VTA destruction; lesions outside the VTA area caused gradual impairment of the locomotor response to stimulation. The facilitatory effect of the electrolytic lesion could be replicated by bicuculline, which significantly facilitated stimulation-induced behavior. Phaclofen exerted slight facilitating influence only at a low dose. No effect of muscimol on the locomotion threshold was found. We conclude that "the contralateral facilitation effect" at the level of VTA reflects the interhemispheric regulation of activity of the dopaminergic (DA) cells in which GABA(A)-mediated interhemispheric communication plays a significant role.

Animals↗

PubMed2000

Whig and anti-whig histories- and other curiosities of social psychology.

In successive editions of the Handbook of Social Psychology (Lindzey, 1954), the focus of the history of the field shifted from the substantive ideas of nineteenth-century thinkers to the successful emergence of a psychological experimental social psychology in the twentieth. Countering this whiggish account, the dominant themes in the present issue involve attempts to portray two parallel paradigm shifts: from a "social" to an "asocial" social psychology, and from a broad-ranging theoretical-philosophical subject to a narrow experimental (psychological) science-changes initiated by Floyd Allport. But such a formulation may be called into question as another version of retrospective history-with inverted, anti-Whig valuations.

Historiography↗

PubMed2003

Experimental models for human implantation.

An understanding of the cellular and molecular basis of blastocyst implantation in the human remains as yet a black box, however, a few experimental models using human and non-human primate species have addressed this issue. This review attempts to highlight, based on experimental evidence, the paradigm shifts in our understanding of the endocrine basis of embryo implantation, and the nature of dialogue between a growing, viable conceptus and maternal endometrial cells in the establishment of 'receptivity' for blastocyst implantation. It is being proposed that an existing inflammation paradigm of blastocyst implantation could be tested using an experimental model to compare tissue behaviour of conceptus associated endometrial cells with that occurring after induction of deciduoma in hormone-primed uterus. We anticipate that an in vitro model of blastocyst implantation using the experimental models of homotypic and heterotypic cultures of uterine epithelial and stromal fibroblast cells expressing structural and functional phenotypic responses as observed in situ may provide us with necessary clues about the temporal and spatial nature of cellular and molecular functions involving various endocrine and paracrine factors at implantation.

Animals↗

PubMed2003

To have and have not: adaptive bereavement by transforming mental ties to the deceased.

Over the past decade, there has been a paradigm shift in the field of bereavement: From the traditional view that insists on the necessity of disengagement, toward a position that postulates the need for a continuing connection. The authors propose to move beyond the dichotomy that was created by the two paradigms and conceive of it as a process of transformation that involves both disengagement and connection. Drawing on theoretical frameworks of control and adaptation, the authors suggest that the relationship with the deceased may be transformed to mental representations of this person that carry substitute value.

Adaptation, Psychological↗

PubMed2006

Heterodimerization and surface localization of G protein coupled receptors.

G protein coupled receptors (GPCRs) are one of the largest human gene families, and are targets for many important therapeutic drugs. Over the last few years, there has been a major paradigm shift in our understanding of how these receptors function. Formerly, GPCRs were thought to exist as monomers that, upon agonist occupation, activated a heterotrimeric G protein to alter the concentrations of specific second messengers. Until recently, this relatively linear cascade has been the standard paradigm for signaling by these molecules. However, it is now clear that this model is not adequate to explain many aspects of GPCR function. We now know that many, if not most, GPCRs form homo- and/or hetero-oligomeric complexes and interact directly with intracellular proteins in addition to G proteins. It now appears that many GPCRs may not function independently, but might more accurately be described as subunits of large multi-protein signaling complexes. These observations raise many important new questions; some of which include: (1) how many functionally and pharmacologically distinct receptor subtypes exist in vivo? (2) Which GPCRs physically associate, and in what stochiometries? (3) What are the roles of individual subunits in binding ligand and activating responses? (4) Are the pharmacological or signaling properties of GPCR heterodimers different from monomers? Since these receptors are the targets for a large number of clinically useful compounds, such information is likely to be of direct therapeutic importance, both in understanding how existing drugs work, but also in discovering novel compounds to treat disease.

Dimerization↗

PubMed1997

Integrating medical informatics into the medical undergraduate curriculum.

The advent of healthcare reform and the rapid application of new technologies have resulted in a paradigm shift in medical practice. Integrating medical Informatics into the full spectrum of medical education is a viral step toward implementing this new instructional model, a step required for the understanding and practice of modern medicine. We have developed an informatics curriculum, a new educational paradigm, and an intranet-based teaching module which are designed to enhance adult-learning principles, life-long self education, and evidence-based critical thinking. Thirty two, fourth year medical students have participated in a one month, full time, independent study focused on but not limited to four topics: mastering the windows-based environment, understanding hospital based information management systems, developing competence in using the internet/intranet and world wide web/HTML, and experiencing distance communication and TeleVideo networks. Each student has completed a clinically relevant independent study project utilizing technology mastered during the course. This initial curriculum offering was developed in conjunction with faculty from the College of Medicine, College of Engineering, College of Education, College of Business, College of Public Health. Florida Center of Instructional Technology, James A. Haley Veterans Hospital, Moffitt Cancer Center, Tampa General Hospital, GTE, Westshore Walk-in Clinic (paperless office), and the Florida Engineering Education Delivery System. Our second step toward the distributive integration process was the introduction of Medical Informatics to first, second and third year medical students. To date, these efforts have focused on undergraduate medical education. Our next step is to offer workshops in Informatics to college of medicine faculty, to residents in post graduate training programs (GME), and ultimately as a method of distance learning in continuing medical education (CME).

Computer Communication Networks↗

PubMed1995

Layer I of primary sensory neocortex: where top-down converges upon bottom-up.

A fundamental paradigm shift is underway in the behavioural neurosciences which promotes renewed discussion of neural correlates of conscious sensation. A growing body of evidence that the primary sensory areas are central to conscious processing is inconsistent with conventional bottom-up models of passive sensory transformation. The new paradigm emphasizes the interaction of top-down corticocortical influences with bottom-up sensory feedback. This review develops the new interactive paradigm with respect to the behaviourally relevant N1 component of the somatosensory evoked response in primary somatosensory neocortex which is only observed during conscious states and predicts touch discrimination behaviour. N1 is generated by layer I excitation apparently in response to backward projections from higher order cortical areas. The backward corticocortical projections mediating top-down influences are anatomically concentrated in layer I where they strongly excite the subpopulation of pyramidal neurons with extensive distal apical dendrites. This subpopulation includes the forward-projecting pyramids subserving corticocortical reentrance as well as the corticobulbar projections mediating cortical control over fine sensory-oriented movements. This interactive paradigm views conscious sensation as an active behaviour with the optimal spatial resolution of primary areas serving as the sensory-motor interface at the major convergence point between reentrant bottom-up and top-down pathways. A device is proposed for the reconstruction of cortical sensory processing based upon the central importance of the primary area as the focus of convergent top-down cortical projections.

Animals↗

PubMed2006

Economic impact of surgical intervention in the treatment of benign prostatic hyperplasia.

The economic burden of benign prostatic hyperplasia (BPH) on our health care system is significant and likely to continue to grow given the burgeoning elderly population. Coincident with the rising number of annual physician office visits and expenditures for BPH has been a dramatic shift in the disease's management, from surgical to medical care. However, long-term cost data call into question the appropriateness of medical therapy as the initial treatment approach for all men with BPH, particularly those with moderate to severe symptoms. Although there has been a paradigm shift away from traditional BPH surgery, there has been renewed interest in the treatment of BPH with novel surgical techniques and minimally invasive surgeries. The economics of surgical interventions for BPH are discussed.

Journal Article↗

PubMed2003

An alternative paradigm for clinical nursing research: an exemplar.

Effectiveness research is undertaken to evaluate the effects of interventions in achieving desired outcomes when tested in the real-world conditions of everyday practice. Although the randomized clinical trial (RCT) is considered the gold standard for effectiveness research, its feasibility, generalizability, and the clinical utility of its results are being questioned. This state of the science prompted the call for a paradigm shift, characterized by alternative methods for clinical research. The alternative methods attempt to account for clinical realities when conducting research, with the goal of minimizing discrepancies in the perspective and assumptions underlying practice and research. In this article a theory-driven approach to intervention evaluation is presented as a viable alternative paradigm for clinical research. The application of this approach demands changes in four aspects of research: participant selection criteria, assignment to treatment options, delivery of the intervention, and selection of outcome measures. The changes are discussed at the conceptual level and illustrated with examples from an ongoing multisite study aimed at determining the usefulness of this theory-driven approach to intervention evaluation.

Clinical Nursing Research↗

PubMedDate not supplied

Restructuring registered nurse curricula.

National initiatives in higher education, health reform, and the nursing curriculum revolution are applied to five curricular patterns for registered nurse (RN) upward mobility baccalaureate education. American Association of Higher Education principles for quality baccalaureate education are applied to the curricular models. The patterns described are: community model, health promotion model, nursing diagnosis model, case management model, and caring model. Three educational strategies for prompting paradigm shifts in RNs who return to school are discussed: collaborative learning, portfolios, and self-assessments. These learning strategies are designed to move the adult student through Perry's phases of cognitive development from duality to relativism. The combination of fresh new curriculum patterns and collaborative learning strategies can empower nurses to discover new paradigms with which to transform the profession.

Career Mobility↗