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At least 1,405 records · Page 78Linked to original sources
PubMed1997

[Specific antibodies against Plasmodium falciparum antigens in immune subjects: I. Comparison of detection/titration methods].

We report a comparative study of specific antibody levels to the blood stages of P. falciparum in individuals living in two different areas with different transmission levels of malaria. We have compared 2 techniques for the detection/titration of antibodies i.e. ELISA and IFI, ELISA being particularly suitable for immuno-epidemiological related studies. A schizont lysate from P. falciparum infected red blood cells from FUP/CB Marburg strain as antigen proved usefullness, as compared with an antigen extracted from a local strain recently adapted to in vitro culture. Using these techniques, high specific antibody responses were found in the villagers' sera and mean levels of antibodies increased with age. Levels of specific IgG were comparable between those two locations, in spite of a ten fold higher level of transmission between the two villages. In contrast, a significantly higher level of IgM in adults living in holoendemic.

Adolescent↗
PubMed2004

Adaptive comanagement for building resilience in social-ecological systems.

Ecosystems are complex adaptive systems that require flexible governance with the ability to respond to environmental feedback. We present, through examples from Sweden and Canada, the development of adaptive comanagement systems, showing how local groups self-organize, learn, and actively adapt to and shape change with social networks that connect institutions and organizations across levels and scales and that facilitate information flows. The development took place through a sequence of responses to environmental events that widened the scope of local management from a particular issue or resource to a broad set of issues related to ecosystem processes across scales and from individual actors, to group of actors to multiple-actor processes. The results suggest that the institutional and organizational landscapes should be approached as carefully as the ecological in order to clarify features that contribute to the resilience of social-ecological systems. These include the following: vision, leadership, and trust; enabling legislation that creates social space for ecosystem management; funds for responding to environmental change and for remedial action; capacity for monitoring and responding to environmental feedback; information flow through social networks; the combination of various sources of information and knowledge; and sense-making and arenas of collaborative learning for ecosystem management. We propose that the self-organizing process of adaptive comanagement development, facilitated by rules and incentives of higher levels, has the potential to expand desirable stability domains of a region and make social-ecological systems more robust to change.

Canada↗
PubMed1985

[Stress and the endogenous opioid system. III. Classification of the opioid system in the process of adaptation].

In this article the effects of stress-induced release of opioid peptides are integrated into the local (LAS) and general adaptation (GAS) syndrome. Findings are explained which plead for a participation in the LAS and AAS in the sense of a reserve mechanism for the maintenance of the homoeostasis. Three areas in which these opioid peptides possibly interact are discussed, articularly the adrenal glands because of their possible importance in effectuation of stress processes. Interactions between opioid system and catecholamines as well as of opioid peptides with substance P entitle to classify the opioid system as an effective regulator of biochemical processes in stress.

Acetylcholine↗
PubMed2001

TNF-alpha -dependent maturation of local dendritic cells is critical for activating the adaptive immune response to virus infection.

Tumor necrosis factor-alpha (TNF-alpha) is well recognized for its role in mediating innate immune responses. However, the mechanisms of TNF-alpha that influence the adaptive immune response to virus infections are not well understood. In this study, we have investigated the role of TNF-alpha in activating the cellular and humoral responses to systemic viral challenge with recombinant replication-defective adenovirus (rAd). Evaluation of T cell function in TNF-alpha-deficient (TNFKO) mice revealed impaired virus-specific proliferation of T cells derived from the draining lymph nodes of the liver. Analysis of dendritic cells (DC) isolated from local draining lymph nodes after systemic challenge showed that DC from TNFKO mice were relatively immature compared with those from strain-matched wild-type mice. In vitro, TNF-alpha was required to mature DC efficiently during virus-mediated stimulation. Adoptive transfer of primed, mature DC into TNFKO mice restored T cell responses and reconstituted anti-adenovirus antibody responses. Thus, TNF-alpha plays a significant role in the maturation of DC after adenovirus challenge both in vitro and in vivo, highlighting the importance of this innate cytokine in activating adaptive immunity to viral challenge.

Adaptation, Physiological↗
PubMed1991

Simulation of local evolutionary dynamics of small populations.

A simple stochastic model assuming continuous traits, normally distributed modifications, selection for fertility and multiplicative fitness was used to simulate phenotypic evolution by "reproducing individuals" in a given fitness landscape. Of particular interest was how small populations cross saddles separating distinct adaptive peaks. The simulated evolution exhibits a strong dualism: at the same level of reproductive errors, sexual reproduction provides significantly better local adaptation and asexual reproduction provides significantly better adaptive dynamics.

Animals↗
PubMedDate not supplied

Training of health care professionals on the special needs of children in the management of disasters: experience in Asia, Africa, and Latin America.

BACKGROUND: Although children are the most vulnerable group in any disaster, limited information exists regarding their unique needs in complex humanitarian emergencies. OBJECTIVE: To review the experiences gained in designing and implementing a training course for international health care professionals in disaster management focused on the needs of children. METHODS: The format, content, learning objectives, teaching methods, course evaluation, and feedback of a training course on managing complex humanitarian emergencies with a focus on the special needs of children were reviewed. RESULTS: The 5-day course was first conducted at Case Western Reserve University in 1996. Since then, it has been replicated 15 times, annually in the United States, and in 7 overseas venues, including Thailand, Pakistan, Ethiopia, Nicaragua, Panama, Syria, and India. Voluntary US and international faculty used a problem-based learning method to train health care workers from developing countries in providing rapid quality care to child disaster victims. The courses were well received in every venue, as evidenced by active participation of local medical professionals, who organized logistics, recruited participants, and led the process of adapting the course to local needs. A remarkable outcome of this training course has been the development of an international group of highly motivated professionals involved in disseminating information to relief workers at a local level and providing a supportive network among themselves. CONCLUSION: A comprehensive training program targeted for health care professionals, conducted by mutually respectful local and international faculty, is an effective instrument for disseminating information and enhancing competence to help children in disasters.

Africa↗
PubMed2005

Image-guided adaptive radiation therapy (IGART): Radiobiological and dose escalation considerations for localized carcinoma of the prostate.

The goal of this work was to evaluate the efficacy of various image-guided adaptive radiation therapy (IGART) techniques to deliver and escalate dose to the prostate in the presence of geometric uncertainties. Five prostate patients with 15-16 treatment CT studies each were retrospectively analyzed. All patients were planned with an 18 MV, six-field conformal technique with a 10 mm margin size and an initial prescription of 70 Gy in 35 fractions. The adaptive strategy employed in this work for patient-specific dose escalation was to increase the prescription dose in 2 Gy-per-fraction increments until the rectum normal tissue complication probability (NTCP) reached a level equal to that of the nominal plan NTCP (i.e., iso-NTCP dose escalation). The various target localization techniques simulated were: (1) daily laser-guided alignment to skin tattoo marks that represents treatment without image-guidance, (2) alignment to bony landmarks with daily portal images, and (3) alignment to the clinical target volume (CTV) with daily CT images. Techniques (1) and (3) were resimulated with a reduced margin size of 5 mm to investigate further dose escalation. When delivering the original clinical prescription dose of 70 Gy in 35 fractions, the "CTV registration" technique yielded the highest tumor control probability (TCP) most frequently, followed by the "bone registration" and "tattoo registration" techniques. However, the differences in TCP among the three techniques were minor when the margin size was 10 mm (< or = 1.1 %). Reducing the margin size to 5 mm significantly degraded the TCP values of the "tattoo registration" technique in two of the five patients, where a large difference was found compared to the other techniques (< or = 11.8 %). The "CTV registration" technique, however, did maintain similar TCP values compared to their 10 mm margin counterpart. In terms of normal tissue sparing, the technique producing the lowest NTCP varied from patient to patient. Reducing the margin size seemed the only sure way to reduce the NTCP significantly, irrespective of the IGART technique employed. In escalating the dose with the iso-NTCP constraint, the largest average gain in dose was observed with the "tattoo registration" technique, followed by the "CTV registration" and "bone registration" techniques. This is attributed to the fact that in three of the five patients, the "tattoo registration" technique yielded the lowest NTCP, hence a greater window of opportunity to escalate the dose was possible with this technique. However, the variation among the five patients was also largest with the "tattoo registration" technique where, in the case of one patient, the required dose actually needed to be below the original prescription dose of 70 Gy to satisfy the iso-NTCP constraint. This was not the case with the "CTV registration" technique where positive and similar dose escalation was allowed on all five patients. Based on these data, an attractive dose escalation strategy may be to implement the "CTV registration" technique (for consistent dosimetric coverage) for daily target localization in combination with a margin reduction (for increased normal tissue sparing).

Dose Fractionation, Radiation↗
PubMed1998

Novel staging tool for localized prostate cancer: a pilot study using genetic adaptive neural networks.

PURPOSE: An estimated $1.5 billion is spent annually for direct medical expenses and an additional $2.5 billion for indirect costs for the management of prostate cancer. Today there are several procedures for staging prostate cancer, including lymph node dissection. Despite these procedures, the accuracy of predicting extracapsular disease remains low (range 37 to 63, mean 45%). Use of multiple staging procedures adds significantly to the costs of managing prostate cancer. Recently artificial intelligence based neural networks have become available for medical applications. Unlike traditional statistical methods, these networks do not assume linearity or homogeneity of variance and, thus, they are more accurate for clinical data. We applied this concept to staging localized prostate cancer and devised an algorithm that can be used for prostate cancer staging. MATERIALS AND METHODS: Our study comprised 1,200 men with clinically organ confined prostate cancer who underwent preoperative staging using serum prostate specific antigen, systematic biopsy and Gleason scoring before radical prostatectomy and lymphadenectomy. The performance of the neural network was validated for a subset of patients and network predictions were compared with actual pathological stage. Mean patient age was 62.9 years, mean serum prostate specific antigen 8.1 ng./ml. and mean biopsy Gleason 6. Of the patients 55% had organ confined disease, 27% positive margins, 8% seminal vesicle involvement and 7% lymph node disease. Of margin positive patients 30% also had seminal vesicle involvement, while of seminal vesicle positive patients 50% also had positive margins. RESULTS: The sensitivity of the network was 81 to 100%, and specificity was 72 to 75% for various predictions of margin, seminal vesicle and lymph node involvement. The negative predictive values tended to be relatively high for all 3 features (range 92 to 100%). The neural network missed only 8% of patients with margin positive disease, and 2% with lymph node and 0% with seminal vesicle involvement. CONCLUSIONS: Our study suggests that neural networks may be useful as an initial staging tool for detection of extracapsular extension in patients with clinically organ confined prostate cancer. These networks preclude unnecessary staging tests for 63% of patients with clinically organ confined prostate cancer.

Algorithms↗
PubMed1988

Reforming the law in action through empirically grounded civil commitment guidelines.

Some assumptions that guided the national task force in developing the Guidelines for Involuntary Civil Commitment are identified and discussed. The task force's multidisciplinary membership is seen as enhancing the credibility of the suggested reforms. The task force developed guidelines instead of a model law, avoiding disputes about the philosophical basis of commitment laws and providing local jurisdictions the liberty to adapt the task force's recommendations to suit local conditions. Both the problems identified and the suggestions offered by the guidelines were based on the empirical experience of local commitment systems. Communication among the components of civil commitment systems was seen as crucial to reform and as achievable through a recommended structural change.

Advisory Committees↗
PubMedDate not supplied

Self-organization of local cortical circuits and cortical orientation maps: a nonlinear Hebbian model of the visual cortex with adaptive lateral couplings.

A nonlinear, recurrent neural network model of the visual cortex is presented. Orientation maps emerge from adaptable afferent as well as plastic local intracortical circuits driven by random input stimuli. Lateral coupling structures self-organize into DOG profiles under the influence of pronounced emerging cortical activity blobs. The model's simplified architecture and features are modeled to largely mimik neurobiological findings.

Animals↗
PubMed1994

Cytoplasmic retinal localization of an evolutionary homolog of the visual pigments.

A rhodopsin-related protein is preferentially expressed at high levels in retinal pigment epithelium (RPE) and in Müller cells. The putative RPE-retinal G protein-coupled receptor (RGR) was localized in light-adapted bovine retina by means of electron microscopic immunocytochemistry. In the RPE, the protein was localized to a widespread intracellular compartment. Except for the region adjacent to the basal surface, the RPE cytoplasm was labeled throughout the cell including the apical surface. In Müller cells also RGR was found in the intracellular compartment, especially in the cytoplasm in the region of the Müller cell endfeet and proximal cell processes. Subcellular fractionation studies of bovine RPE and neural retina indicated that RGR is a membrane-bound protein. The intracellular localization of RGR is a unique variation in the subcellular distribution of seven-transmembrane-domain receptors and suggests an unconventional role for RGR in the signal transduction process.

Amino Acid Sequence↗
PubMed2003

Lipopolysaccharide or whole bacteria block the conversion of inflammatory monocytes into dendritic cells in vivo.

Monocytes can develop into dendritic cells (DCs) that migrate to lymph nodes (LNs) and present antigens to T cells. However, we find that this differentiation is blocked when monocytes accumulate subcutaneously in response to bacteria or lipopolysaccharide (LPS). The inhibition of DC differentiation is mediated by the bacteria and in conjunction with inflammatory cells recruited at the site of injection. Inhibition of migratory DC development was reversed in Toll-like receptor (TLR)4-mutated mice when LPS, but not whole bacteria, was injected, suggesting that TLR4 is one but not the only mediator of the inhibition. The block imposed by bacteria was partly relieved by the absence of interleukin (IL)-12 p40, but not by individual absence of several cytokines involved in DC differentiation or in inflammation, i.e., IL-6, IL-10, IL-12 p35, and interferon gamma. Consistent with the inability of monocytes to yield migrating DCs, and the finding that other DCs had limited access to particulate or bacterial antigens, these antigens were weakly presented to T cells in the draining LN. These results illustrate that bacteria-associated signals can have a negative regulatory role on adaptive immunity and that local innate responses for containment of infectious bacteria can at least initially supersede development of adaptive responses.

Animals↗
PubMed1994

Product definition for healthcare contracting: an overview of approaches to measuring hospital output with reference to the UK internal market.

OBJECTIVE: In many industrialised countries, health care third party payers are moving towards contracted provision arrangements with suppliers of hospital care. Essential to such a process is a standard approach to quantifying the care provided. This paper aims to outline the possible approaches to hospital product definition for the UK National Health Service, and recommends appropriate further research. METHODS: All published and unpublished studies on hospital output measurement in the NHS since 1980 were sought for the purposes of the review. This included both discursive and empirical work, and no exclusion criteria were applied. Most empirical reports on this topic, however, come from the United States. Consequently, the published reports since 1980 from the USA, accessed from the Medline and Healthplan CD-ROM databases, have also been included in the overview. CONCLUSIONS: Where data are sufficient, the true casemix approach offers advantages over other methods of output measurement. In the UK NHS, two systems--diagnosis-related groups (DRGs) and healthcare resource groups (HRGs)--are the only casemix measures that have achieved any significant degree of attention. DRGs have been extensively evaluated internationally, and explain variations in resource use in the UK slightly better than do HRGs. As a local product, HRGs can be more easily adapted to the specific needs of the NHS internal market, however, and will thus probably emerge as a better measure for the UK in the long term. In both cases, locally derived cost weights are unavailable, and their development constitutes a major requirement for use in contracting. Adaptations for long stay and outpatient hospital episodes would enhance the usefulness of hospital casemix systems in the NHS. Existing approaches, such as specialty based classifications, are neither standardised nor predictive of resource use, and would be better replaced by casemix systems. Other countries facing similar choices between casemix measurement approaches will need to consider the "trade off" between the adaptability of locally derived systems on the one hand and the low cost, rapidly accessible results, and availability of international comparative data of an imported approach on the other.

Contract Services↗
PubMed2000

Case study of an inter-professional and inter-organisational programme to adapt, implement and evaluate clinical guidelines in secondary care.

This paper describes the implementation of a clinical guideline across three acute Trusts. A Clinical Effectiveness Steering Group identified prevention of venous thromboembolism as a health priority. A local guideline development group adapted the recommendations of an existing review and produced a local guideline. Then, a multidisciplinary implementation group developed the practical aspects of implementing guidelines into routine daily practice. They identified appropriate staff to carry out risk assessment and to administer appropriate prophylaxis, as necessary. They also produced a "guideline pack" containing a training resource manual and implementation aids. Following this a multiple strategy implementation programme was used to introduce the guidelines, and an evaluation was carried out eight to ten months after the introduction of the guidelines. The evaluation identified a number of areas for improving current practice. Guideline implementation is a complex, time-consuming process.

Antibiotic Prophylaxis↗
PubMed2001

Involvement of antioxidants and lipid peroxidation in the adaptation of two cool-season grasses to localized drought stress.

In natural environments, drought often occurs in surface soil while water is available for plant uptake deeper in the soil profile. The objective of the study was to examine the involvement of antioxidant metabolism and lipid peroxidation in the responses of two cool-season grasses to surface soil drying. Kentucky bluegrass (Poa pratensis L) and tall fescue (Festuca arundinacea Schreb.) were grown in split tubes, consisting of two sections (each 10 cm in diameter and 20 cm long). Grasses were subjected to three soil moisture regimes: (a) well-watered control: whole soil profile was watered; (b) surface drying: surface 20 cm of soil was dried by withholding irrigation and the lower 20 cm of soil was watered; (c) full drying: whole soil profile was dried. Surface drying had no effects on relative water content (RWC) and chlorophyll content (Chl) for both grasses and only slightly reduced shoot growth for tall fescue. Superoxide dismutase (SOD) activity increased, while catalase (CAT) and peroxidase (POD) activities remained unchanged during most periods of surface drying. Malondialdehyde (MDA) content was unaffected by surface drying for tall fescue, but increased initially and then decreased to the control level for Kentucky bluegrass. Under full drying, RWC, Chl content, and shoot dry weight decreased, but MDA content increased in both grasses; SOD and POD activities initially increased transiently and then decreased; CAT remained unchanged for 25 days and then decreased. These results suggested that both Kentucky bluegrass and tall fescue were capable of surviving surface soil drying. This capability could be related to increases in antioxidant activities, particularly SOD and CAT. However, full drying suppressed antioxidant activities and induced lipid peroxidation.

Journal Article↗
PubMed1999

Validation of a noninvasive measure of local myocardial repolarization in a conscious human model: adaptation of repolarization to changes in rate.

INTRODUCTION: A commercial pacemaker sensor measure of the unipolar endocardial stimulus to T wave interval may accurately reflect changes in the monophasic action potential duration at 90% repolarization (APD90). This sensor system was used to study the kinetics of adaptation of repolarization duration to changes in heart rate in humans. METHODS AND RESULTS: Patients were studied using an external pacemaker capable of displaying all stimulus to T wave intervals for each paced beat. Right ventricular stimulation was delivered via the pacemaker and compared simultaneously to APD90. Steady-state pacing was simulated by 60 seconds of pacing at cycle lengths (CLs) 350 to 700 msec. Adaptation to a new ventricular rate was analyzed with a sudden 200-msec decrease in CL. The relation between repolarization measure and steady-state CL (n = 16) was linear with a slope of 0.16 and 0.19 for APD90 and stimulus to T wave interval, respectively (P = NS). The adaptation of both repolarization measures to a sudden change in rate were best modeled by a biexponential function. Stimulus to T wave interval exhibited a parallel course to APD90, and an analysis of normalized differences between APD90 and stimulus to T wave interval followed an approximately normal distribution, with 93.5% of the paired differences within 2 SD of the mean. CONCLUSION: A pacemaker sensor measure of stimulus to T wave interval accurately parallels APD90 during both steady-state and sudden changes in rate. Repolarization in human endocardium follows a linear relation to steady-state CL and adapts to a new rate with a biexponential function. This model represents a novel method for studying human cardiac repolarization.

Action Potentials↗
PubMed2000

Adaptive eigenvalue decomposition algorithm for passive acoustic source localization

To find the position of an acoustic source in a room, the relative delay between two (or more) microphone signals for the direct sound must be determined. The generalized cross-correlation method is the most popular technique to do so and is well explained in a landmark paper by Knapp and Carter. In this paper, a new approach is proposed that is based on eigenvalue decomposition. Indeed, the eigenvector corresponding to the minimum eigenvalue of the covariance matrix of the microphone signals contains the impulse responses between the source and the microphone signals (and therefore all the information we need for time delay estimation). In experiments, the proposed algorithm performs well and is very accurate.

Journal Article↗