Search PubMed⌕ Search

SEARCH · Search PubMed

Results for “predictability of adaptation”

Search indexed PubMed citations on genomics, clinical trials, systematic reviews and public health. Explore titles, authors and supplied subject terms, then open the PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 649 records · Page 36Linked to original sources
PubMed1989

Longitudinal impact of interhousehold caregiving on adult children's mental health.

The wear-and-tear hypothesis of caregiving (the longer care provided, the more psychological strain on caregivers) was examined using panel survey data from 112 adult children providing interhousehold care to an impaired elderly parent. Measures included subjective caregiving stress and perceived caregiving effectiveness ("wear") and depression and affect balance ("tear"). Contrary to the hypothesis, data revealed variability in children's adaptation to caregiving, improvement rather than deterioration being the norm. In a recursive path model, both subjective stress and perceived effectiveness were significant predictors of changes in depression. Depression was not significantly related to duration of caregiving. Discussion suggests that future researchers consider other types of caregivers and care settings, factors predicting variability in caregivers' adaptation over time, and changes as well as stability in care arrangements.

Adult↗
PubMed2006

A cold-sensitive Listeria monocytogenes mutant has a transposon insertion in a gene encoding a putative membrane protein and shows altered (p)ppGpp levels.

A cold-sensitive Listeria monocytogenes mutant designated cld-14 was obtained by transposon Tn917 mutagenesis. The gene interrupted by Tn917 in cld-14 was the L. monocytogenes LMOf2365_1485 homolog, which exhibits 45.7% homology to the Bacillus subtilis yqfF locus. LMOf2365_1485, here designated pgpH, encodes a putative integral membrane protein with a predicted molecular mass of 81 kDa. PgpH is predicted to contain a conserved N-terminal signal peptide sequence, seven transmembrane helices, and a hydrophilic C terminus, which likely extends into the cytosol. The Tn917 insertion in pgpH is predicted to result in production of a premature polypeptide truncated at the fifth transmembrane domain. The C terminus of PgpH, which is probably absent in cld-14, contains a highly conserved HD domain that belongs to a metal-dependent phosphohydrolase family. Strain cld-14 accumulated higher levels of (p)ppGpp than the wild type accumulated, indicating that the function of PgpH may be to adjust cellular (p)ppGpp levels during low-temperature growth. The cld-14pgpH(+) complemented strain was able to grow at a low temperature, like the parent strain, providing direct evidence that the activity of PgpH is important in low-temperature adaptation. Because of its predicted membrane location, PgpH may play a critical role in sensing the environmental temperature and altering cellular (p)ppGpp levels to allow the organism to adapt to low temperatures.

Bacterial Proteins↗
PubMed2004

Prediction of visual perceptions with artificial neural networks in a visual prosthesis for the blind.

Within the framework of the OPTIVIP project, an optic nerve based visual prosthesis is developed in order to restore partial vision to the blind. One of the main challenges is to understand, decode and model the physiological process linking the stimulating parameters to the visual sensations produced in the visual field of a blind volunteer. We propose to use adaptive neural techniques. Two prediction models are investigated. The first one is a grey-box model exploiting the neurophysiological knowledge available up to now. It combines a neurophysiological model with artificial neural networks, such as multi-layer perceptrons and radial basis function networks, in order to predict the features of the visual perceptions. The second model is entirely of the black-box type. We show that both models provide satisfactory prediction tools and achieve similar prediction accuracies. Moreover, we demonstrate that significant improvement (25%) was gained with respect to linear statistical methods, suggesting that the biological process is strongly non-linear.

Blindness↗
PubMed2006

Adaptive functional differentiation of dendritic cells: integrating the network of extra- and intracellular signals.

Phenotypic maturation, cytokine secretion, and migration are distinct functional characteristics of dendritic cells (DCs). These functions are independently regulated by a number of extracellular variables, such as type, strength, and persistence of an array of soluble and membrane-bound mediators. Since the exact composition of these variables in response to infection may differ between individuals, the intracellular signaling pathways activated by these extracellular networks may more closely correlate with DC function and predict the course of adaptive immunity. We found that activation of p38 kinase (p38K), extracellular signal-related kinase 1/2 (ERK1/2), and phosphatidylcholine-specific phospholipase C (PC-PLC) enhanced cytokine secretion, whereas p38K, cyclic adenosine monophosphate (cAMP), and PC-PLC enhanced migration. In contrast, phosphatidylinositol 3-kinase (PI3K)/Akt-1 and cAMP inhibited cytokine secretion while ERK1/2 inhibited migration. Migration and cytokine secretion further differed in their sensitivity to inhibition over time. However, although DCs could be manipulated to express migration, cytokine secretion, or both, the level of activation or persistence of intracellular pathway signaling was not predictive. Our results suggest a modular organization of function. We hypothesize that the expression of specific DC functions integrates a large variety of activating and inhibitory variables, and is represented by the formation of a functional unit of molecular networks-the signal response module (SRM). The combined activities of these modules define the functional outcome of DC activation.

Cell Differentiation↗
PubMed1975

The adaptation of cochlear and brainstem auditory evoked potentials in humans.

The adaptation of the responses from the cochlear nerve and the auditory brainstem nuclei was studied using a burst of four clicks as the stimulus. Nine experimental conditions were obtained from three stimulus levels (60, 70 and 80 dB SL) and from three intervals between click in the burst (15, 24 and 32.5 msec). Six subjects were each tested three times for each of the experimental conditions and the techniques used and results obtained are summarized. Various models of the adaptation of the brainstem responses are proposed which predict different results. The results for the adaptation of the N1 response are basically in agreement with previous work, and the more central brainstem responses showed less adaptation than the peripheral responses. These findings may be explained by postulating different adaptation mechanisms for the peripheral and central responses. The 60dB stimulus level condition gave rise to more adaptation than the 80dB level, and this is in agreement with studies of low and high threshold reception systems reported elsewhere.

Adaptation, Physiological↗
PubMed1997

Fuzzy logic for model adaptation of a pharmacokinetic-based closed loop delivery system for pancuronium.

In this paper, we investigate the ability of fuzzy to adapt the parameters of a pharmacokinetic and pharmacodynamic model-based controller for the delivery of the muscle relaxant pancuronium. The system uses the model to control the rate of drug delivery and uses feedback from a sensor which measures muscle relaxation level to adapt the model using fuzzy logic. The control strategy administers mini-bolus doses of pancuronium and modulates the magnitude and time interval between the bolus doses to maintain a patient's muscle relaxation within an allowable range specified by the user. Before each new dose is given, the fuzzy logic adaptation scheme uses the error between the predicted patient response and the measured response to adapt the model. The system was tested using computer simulation by varying the parameters of the model by 50% from their nominal values. It was also evaluated in a clinical trial of five patients undergoing surgical procedures lasting 5 h or longer.

Adult↗
PubMed1999

Nonlinear model-based predictive control of non-depolarizing muscle relaxants using neural networks.

Neuromuscular blockade can be relatively easily measured in the clinical setting. Consequently, closed-loop control can be exercised by measuring the neuromuscular activity, calculating the dose of drug necessary to achieve a predefined degree of neuromuscular blockade and finally directing an infusion pump. Recently introduced short-acting blocking agents like mivacurium provide benefits for the clinical routine due to a small onset time and half life. In order to provide a stable blockade for different groups of patients a fast and highly adaptable control unit is needed. Furthermore its development should not imply costly investigations for determining a pharmacological model. The fulfilling of these requirements yield a self-adapting model-based predictive control system. The application of artificial neural networks allows an appropriate adjustment of specific parameters without the knowledge of inner pharmacodynamic processes. In a clinical study the EMG module within a Datex AS/3 monitor was used to measure the blockade and a Grasepy 3500 infusion pump for i.v. administration of mivacurium to 35 patients (ASA I-III). The performance of the novel system (mean of the T1 error: -0.32 +/- 1.7) compares favourably with closed-loop controllers demonstrated in the past. These promising results and the easy adaption to other blocking agents encourage to apply this technology even for delivering hypnotic drugs.

Electromyography↗
PubMed1990

Evolution in bacterial plasmids and levels of selection.

Gene flow between different reproductive units such as bacterial plasmids and chromosomes presents unusual problems for evolutionary analysis. Far more than in eukaryotes, reproductive advantages at several levels of selection--genes, transposons, plasmids, cells, and clones--must be considered simultaneously to understand plasmid evolution. No level consistently prevails in conflict situations, and some reproductive units carry genes that restrain their own reproduction or survival, apparently to enhance the reproduction or survival of the higher-level reproductive units that carry them. Despite gene flow between plasmids and chromosomes, genes for certain functions show strong tendencies to occur on plasmids while others consistently occur on chromosomes. Functions generally associated with plasmids are diverse, but all are useful only in locally restricted contexts; it is argued that the selective consequences of the greater horizontal (within generation) transmission of plasmids are responsible for this pattern. The tendency for prokaryote transposons, which are also horizontally mobile, to carry genes similar to those commonly on plasmids supports this argument. The apparent trends in eukaryote plasmids and transposons to lack these same characters also accords with predictions of the local adaptation hypothesis, because genes on these genetic units are generally no more horizontally mobile than chromosomal genes. There are theoretical reasons to expect that plasmid genes tend to evolve more rapidly than chromosomal genes. "The selfish interests of genes have manifestly produced 'vehicles' in the forms of organelles, cells, individuals and yet higher units. If evolution is to predict as well as describe, then selfish interests must be understood in the framework of the constraints and opportunities generated by these 'vehicles'" (Buss, 1987, p. 182).

Bacteria↗
PubMed1996

A scoring system for predicting group A streptococcal throat infection.

BACKGROUND: Sore throat is very common in general practice and is usually caused by viral infection. Nevertheless, up to 95% of patients may be treated with antibiotics. Previous diagnostic systems have not transferred well from one area to another because of an inability to allow for changing prevalence of streptococcus. AIM: To measure the occurrence rates of symptoms and signs in sore throat patients with and without streptococcal infection, and to develop a Bayesian scoring system which is easily adapted for prevalence to predict if patients have bacterial infection. METHOD: Occurrence rates of symptoms and signs were measured for 206 patients with sore throat symptoms over a 3-year period. Bayesian probability scores (B-scores) for each data item were calculated from the ocurrence rates in the patients with positive throat cultures for group A streptococci and the rates in patients with negative throat cultures. The B-score values were then used to predict the probability of positive culture for each patient. RESULTS: The streptococcal throat B-score system predicted positive culture with a sensitivity of 71% and a specificity of 71%. In comparison, the unaided general practitioners predicted infection with a sensitivity of 61% and a specificity of 65%. If the B-score prediction had been used to decide on treatment, more patients with streptococci present on culture would have been treated with antibiotic (71% instead of 68%) and appreciably fewer patients with negative streptococcal cultures would have been treated (29% instead of 59%). CONCLUSION: Use of the B-score system could result in significant savings in unnecessary antibiotic prescription, and unnecessary throat swab cultures, while achieving better levels of treatment.

Adolescent↗
PubMed1986

Concurrent and predictive validity of components of disordered thinking in schizophrenia.

Although the various manifestations of disordered thought have played a central role in diagnostic and theoretical considerations of schizophrenia, such symptoms have not been found specific to schizophrenia, and at best have shown weak relations to outcome. As part of a 7-year followup study of a sample of young, acute, psychotic inpatients, we explored the hypothesis that despite these poor results there might be particular components of disordered thought that might have prognostic utility and be able to discriminate narrowly defined schizophrenics. Using extant symptom scales as our models, we constructed five internally consistent scales of disordered thought from behavioral ratings made using the Psychotic Inpatient Profile--Poverty of Speech, Attentional Impairment, Incoherence, Delusions, and Hallucinations. We tested the ability of these scales to predict various aspects of outcome adaptation including outcome diagnosis. In general, the Attentional Impairment scale demonstrated the best prognostic utility, predicting poorer outcome in several domains. Paradoxically, patients diagnosed by Research Diagnostic Criteria (RDC) as definite schizophrenic at outcome had been rated as showing less attentional impairment than probable and nonschizophrenics. An examination of the pattern of correlations between Attentional Impairment and performance on cognitive tasks suggested that attentional difficulties may be related to different underlying cognitive processes in those diagnosed schizophrenic and nonschizophrenic at outcome by RDC.

Adult↗
PubMed1996

Construing benefits from adversity: adaptational significance and dispositional underpinnings.

The discovery of benefits from living with adversity has been implicated in psychological well-being in numerous investigations, is pivotal to several prominent theories of cognitive adaptation to threat, and can be predicted by personality differences. This article summarizes the prevalence and adaptive significance of finding benefits from major medical problems, locates the place of benefit-finding in stress and coping theories, and examines how it may be shaped by specific psychological dispositions such as optimism and hope and by broader personality traits such as Extraversion and Openness to Experience. The distinction between beliefs about benefits from adversity (benefit-finding) and the use of such knowledge as a deliberate strategy of coping with the problem (benefit-reminding) is underscored and illustrated by daily process research on coping with chronic pain.

Adaptation, Psychological↗
PubMed1991

Testing hypotheses derived from the Roy Adaptation Model.

This study investigated the role of perception and biopsychosocial adaptation in patients with cancer entering an aggressive cancer treatment program. The Roy adaptation model provided the framework from which hypotheses were derived and tested. The hypotheses proposed that physiological stimuli are translated by the cognator through perception that alters the biopsychosocial responses. Forty-five patients were tested as they entered into the chemotherapy program. The APACHE II was used to measure actual physiological status; the Symptom Distress Profile was used to measure subjects' perceived physiological discomfort, and the Sickness Impact Profile was used to measure subjects' perceived effect of the cancer on their psychosocial adaptation. The results supported the theoretical predictions that perception of symptoms is positively correlated with psychosocial adaptation and not with actual physiological status. In addition, perception of symptoms and psychosocial adaptation were correlated with survival at six months and not with actual physiological status. Discussion of findings addresses theoretical and practice issues.

Adaptation, Psychological↗
PubMed2001

Effect of rotation and translation on the expected benefit of an ideal method to correct the eye's higher-order aberrations.

An ideal correcting method, such as a customized contact lens, laser refractive surgery, or adaptive optics, that corrects higher-order aberrations as well as defocus and astigmatism could improve vision. The benefit achieved with this ideal method will be limited by decentration. To estimate the significance of this potential limitation we studied the effect on image quality expected when an ideal correcting method translates or rotates with respect to the eye's pupil. Actual wave aberrations were obtained from ten human eyes for a 7.3-mm pupil with a Shack-Hartmann sensor. We computed the residual aberrations that appear as a result of translation or rotation of an otherwise ideal correction. The model is valid for adaptive optics, contact lenses, and phase plates, but it constitutes only a first approximation to the laser refractive surgery case where tissue removal occurs. Calculations suggest that the typical decentrations will reduce only slightly the optical benefits expected from an ideal correcting method. For typical decentrations the ideal correcting method offers a benefit in modulation 2-4 times higher (1.5-2 times in white light) than with a standard correction of defocus and astigmatism. We obtained analytical expressions that show the impact of translation and rotation on individual Zernike terms. These calculations also reveal which aberrations are most beneficial to correct. We provided practical rules to implement a selective correction depending on the amount of decentration. An experimental study was performed with an aberrated artificial eye corrected with an adaptive optics system, validating the theoretical predictions. The results in a keratoconic subject, also corrected with adaptive optics, showed that important benefits are obtained despite decentrations in highly aberrated eyes.

Eye↗
PubMed2026

Integrative multi-omics and single-cell analysis identifies EGFR pathway activation and metabolic reprogramming as potential synthetic lethal vulnerabilities in resistance to the FGFR inhibitor AZD4547.

BACKGROUND: Although fibroblast growth factor receptor (FGFR) inhibitors (FGFRi) have demonstrated clinical promise, the inevitable emergence of acquired resistance remains a critical bottleneck, severely compromising their long-term clinical efficacy. The pan-cancer molecular landscape and heterogeneous mechanisms driving this resistance, ranging from genetic alterations to dynamic network rewiring, remain poorly understood. METHODS: We integrated large-scale pharmacogenomic profiling of the FGFR inhibitor AZD4547 from the GDSC2 and PRISM databases with single-cell RNA sequencing to dissect the multi-omics landscape of FGFRi resistance across 312 cell lines from 8 cancer types. This multi-omics framework was further extended by machine learning modeling and systematic synthetic lethality screening to uncover actionable therapeutic targets. In vitro viability assays and western blot analysis were subsequently conducted to experimentally evaluate the predicted FGFR-EGFR synthetic lethality. RESULTS: Our dual-database analysis unveiled a multi-dimensional atlas of FGFRi resistance. We identified cancer-specific genomic drivers, such as ELF4 amplification in glioblastoma, alongside key transcriptomic markers including UCP2 and FSCN1, highlighting a shift towards metabolic reprogramming and epithelial-mesenchymal transition (EMT). Single-cell analysis unveiled that resistance is linked to the heterogeneous enrichment of baseline subpopulations characterized by distinct metaprograms, including cell-cycle dysregulation. Furthermore, a random forest model built on a LASSO-derived transcriptomic signature was constructed, demonstrating promising predictive capability for AZD4547 sensitivity (mean test-set AUC = 0.73, 95% CI [0.63, 0.80]); the signature generalized well to erdafitinib but showed limited transferability to some other FGFR inhibitors (e.g. pemigatinib, BGJ398). Most notably, our synthetic lethal screening revealed a convergent reliance on compensatory RTK signaling (specifically EGFR pathway enrichment) and downstream MAPK/PI3K cascades in resistant phenotypes, providing converging computational evidence for EGFR pathway activation as an adaptive bypass mechanism. This predicted synthetic lethality was experimentally supported in two FGFR-dependent cell line models (RT112 and CCLP1), in which combined FGFR-EGFR inhibition produced marked synergistic antiproliferative effects. CONCLUSIONS: This study establishes a comprehensive multi-omics atlas of resistance to the FGFR inhibitor AZD4547, delineating convergent mechanisms of metabolic reprogramming and EGFR-mediated bypass signaling. Our findings characterize the resistance as a dynamic network rewiring and nominate rational combination strategies to overcome this therapeutic bottleneck. While FGFR-EGFR co-inhibition is experimentally supported, metabolic co-targeting remains a computationally derived, hypothesis-generating strategy.

Benzamides↗
PubMed2001

Performance of an adaptive beamforming noise reduction scheme for hearing aid applications. II. Experimental verification of the predictions.

A method to predict the amount of noise reduction which can be achieved using a two-microphone adaptive beamforming noise reduction system for hearing aids [J. Acoust. Soc. Am. 109, 1123 (2001)] is verified experimentally. 34 experiments are performed in real environments and 58 in simulated environments and the results are compared to the predictions. In all experiments, one noise source and one target signal source are present. Starting from a setting in a moderately reverberant room (reverberation time 0.42 s, volume 34 m3, distance between listener and either sound source 1 m, length of the adaptive filter 25 ms), eight different parameters of the acoustical environment and three different design parameters of the adaptive beamformer were systematically varied. For those experiments, in which the direct-to-reverberant ratios of the noise signal is +3 dB or less, the difference between the predicted and the measured improvement in signal-to-noise ratio (SNR) is -0.21+/-0.59 dB for real environments and -0.25+/-0.51 dB for simulated environments (average +/- standard deviation). At higher direct-to-reverberant ratios, SNR improvement is systematically underestimated by up to 5.34 dB. The parameters with the greatest influence on the performance of the adaptive beamformer have been found to be the direct-to-reverberant ratio of the noise source, the reverberation time of the acoustic environment, and the length of the adaptive filter.

Acoustics↗
PubMed2004

The influence of duration and level on human sound localization.

The localization of sounds in the vertical plane (elevation) deteriorates for short-duration wideband sounds at moderate to high intensities. The effect is described by a systematic decrease of the elevation gain (slope of stimulus-response relation) at short sound durations. Two hypotheses have been proposed to explain this finding. Either the sound localization system integrates over a time window that is too short to accurately extract the spectral localization cues (neural integration hypothesis), or the effect results from cochlear saturation at high intensities (adaptation hypothesis). While the neural integration model predicts that elevation gain is independent of sound level, the adaptation hypothesis holds that low elevation gains for short-duration sounds are only obtained at high intensities. Here, these predictions are tested over a larger range of stimulus parameters than has been done so far. Subjects responded with rapid head movements to noise bursts in the two-dimensional frontal space. Stimulus durations ranged from 3 to 100 ms; sound levels from 26 to 73 dB SPL. Results show that the elevation gain decreases for short noise bursts at all sound levels, a finding that supports the integration model. On the other hand, the short-duration gain also decreases at high sound levels, which is in line with the adaptation hypothesis. The finding that elevation gain was a nonmonotonic function of sound level for all sound durations, however, is predicted by neither model. It is concluded that both mechanisms underlie the elevation gain effect and a conceptual model is proposed to reconcile these findings.

Adult↗
PubMed2005

Anaphylaxis: how do you live with it?

This article reports on a study of the needs of families coping with life-threatening allergies in a child. Due to the scarcity of publications on the psychosocial dimensions of anaphylaxis, the authors draw on selected literature on family coping with chronic illness, asthma, and allergy to provide a conceptual context for the research and discussion of findings. Using qualitative methodology, parents from 17 families were interviewed about their experiences adjusting to a diagnosis of anaphylaxis in a child. From participants' responses about the nature and sources of information and support, parenting dilemmas, family activities, anxieties, challenges, and coping strategies, the authors identify patterns in the adaptive processes related to predictable developmental and episodic events that increase anxiety and support needs. Social work clinicians and other family-serving professionals can help families maintain an optimal balance between protective and debilitating anxiety. Potential interventions in community and health settings are suggested.

Adaptation, Psychological↗
PubMed2001

A topographic instructive signal guides the adjustment of the auditory space map in the optic tectum.

Maps of auditory space in the midbrain of the barn owl (Tyto alba) are calibrated by visual experience. When owls are raised wearing prismatic spectacles that displace the visual field in azimuth, the auditory receptive fields of neurons in the optic tectum shift to compensate for the optical displacement of the visual field. This shift results primarily from a shift in the tuning of tectal neurons for interaural time difference. The visually based instructive signal that guides this plasticity could be based on a topographic, point-by-point comparison between auditory and visual space maps or on a foveation-dependent visual assessment of the accuracy of auditory orienting responses. To distinguish between these two possibilities, we subjected owls to optical conditions that differed in the center of gaze and the visual periphery. A topographic signal would cause the portions of the space map representing the central and peripheral regions of visual space to adjust differently, according to the optical conditions that exist in each region. In contrast, a foveation-based signal would cause both portions of the map to adjust similarly, according to the optical conditions that exist at the center of gaze. In six of seven experiments, adaptive changes were as predicted by a topographic instructive signal. Although the results do not rule out the possible contribution of a foveation-based signal, they demonstrate that a topographic instructive signal is, indeed, involved in the calibration of the auditory space map in the barn owl optic tectum.

Adaptation, Physiological↗