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PubMed2005

Affect and pain in rheumatoid arthritis: do individual differences in affective regulation and affective intensity predict emotional recovery from pain?

BACKGROUND: Individual differences in adaptation to rheumatoid arthritis are not fully accounted for by illness severity or duration of symptoms. PURPOSE: In this study, we assessed differences in affect regulation and affect intensity as variables that might be important for identifying women with rheumatoid arthritis who are resilient versus those who have disrupted moods following pain exacerbations. METHOD: Specifically, affective regulation, affect intensity, active coping, neuroticism and weekly reports of pain, positive affect, and negative affect were assessed in a sample of 81 women diagnosed with rheumatoid arthritis. RESULTS: Our results indicated that affective regulation, affect intensity, and active coping played important but distinct roles in the ebb and flow of negative and positive affect. In particular, active coping was related to positive affect, whereas affective regulation and affect intensity showed interactive effects, moderating the prospective relationship between pain and negative affect and pain and positive affect. CONCLUSION: Overall, this study suggests that recovery from rheumatoid arthritis pain can be swift, except for those women who have difficulty regulating strong unpleasant affect.

Adaptation, Psychological↗
PubMed2025

Evolutionary Genomics Unravels the Responses and Adaptation to Climate Change in a Key Alpine Forest Tree Species.

Despite widespread biodiversity loss, our understanding of how species and populations will respond to accelerated climate change remains limited. In this study, we integrate population genomics, experimental evolution, and environmental modeling to elucidate the evolutionary responses to climate change in Populus lasiocarpa, a key alpine forest tree species primarily distributed in the mountainous regions of a global biodiversity hotspot. Over historical timescales, our findings demonstrate that demographic dynamics, divergent selection, and long-term balancing selection have shaped and maintained genetic variation within and between populations. In examining genomic signatures of contemporary climate adaptation, we found that haplotype blocks, potentially caused by inversion polymorphisms that suppress recombination, are linked to enriched combinations of locally adaptive environmental variations. We further assessed the relative contributions of environmentally induced plastic responses, constitutive expression divergence between genetic clusters, and their interactions in driving gene expression variation and divergence. Notably, we observed a strong correlation between sequence divergence and constitutive differential expression among genetic clusters. Finally, by incorporating genetic adaptation, migration, and genetic load into our predictions of population-level climate change risks, we identified western populations-primarily distributed in the Hengduan Mountains, a region known for its environmental heterogeneity and significant biodiversity-as the most vulnerable to climate change. These populations should be prioritized for conservation and management. Overall, our study advances the understanding of the relative roles of long-term natural selection, local environmental adaptation, and immediate plastic expression changes in shaping the responses of natural populations of keystone species to climate change.

Climate Change↗
PubMed2002

Energy integration describes sound-intensity coding in an insect auditory system.

We investigate the transduction of sound stimuli into neural responses and focus on locust auditory receptor cells. As in other mechanosensory model systems, these neurons integrate acoustic inputs over a fairly broad frequency range. To test three alternative hypotheses about the nature of this spectral integration (amplitude, energy, pressure), we perform intracellular recordings while stimulating with superpositions of pure tones. On the basis of online data analysis and automatic feedback to the stimulus generator, we systematically explore regions in stimulus space that lead to the same level of neural activity. Focusing on such iso-firing-rate regions allows for a rigorous quantitative comparison of the electrophysiological data with predictions from the three hypotheses that is independent of nonlinearities induced by the spike dynamics. We find that the dependence of the firing rates of the receptors on the composition of the frequency spectrum can be well described by an energy-integrator model. This result holds at stimulus onset as well as for the steady-state response, including the case in which adaptation effects depend on the stimulus spectrum. Predictions of the model for the responses to bandpass-filtered noise stimuli are verified accurately. Together, our data suggest that the sound-intensity coding of the receptors can be understood as a three-step process, composed of a linear filter, a summation of the energy contributions in the frequency domain, and a firing-rate encoding of the resulting effective sound intensity. These findings set quantitative constraints for future biophysical models.

Acoustic Stimulation↗
PubMed1999

Exercise-induced muscle damage and potential mechanisms for the repeated bout effect.

Unfamiliar, predominantly eccentric exercise, frequently results in muscle damage. A repeated bout of similar eccentric exercise results in less damage and is referred to as the 'repeated bout effect'. Despite numerous studies that have clearly demonstrated the repeated bout effect, there is little consensus as to the actual mechanism. In general, the adaptation has been attributed to neural, connective tissue or cellular adaptations. Other possible mechanisms include, adaptation in excitation-contraction coupling or adaptation in the inflammatory response. The 'neural theory' predicts that the initial damage is a result of high stress on a relatively small number of active fast-twitch fibres. For the repeated bout, an increase in motor unit activation and/or a shift to slow-twitch fibre activation distributes the contractile stress over a larger number of active fibres. Although eccentric training results in marked increases in motor unit activation, specific adaptations to a single bout of eccentric exercise have not been examined. The 'connective tissue theory' predicts that muscle damage occurs when the noncontractile connective tissue elements are disrupted and myofibrillar integrity is lost. Indirect evidence suggests that remodelling of the intermediate filaments and/or increased intramuscular connective tissue are responsible for the repeated bout effect. The 'cellular theory' predicts that muscle damage is the result of irreversible sarcomere strain during eccentric contractions. Sarcomere lengths are thought to be highly non-uniform during eccentric contractions, with some sarcomeres stretched beyond myofilament overlap. Loss of contractile integrity results in sarcomere strain and is seen as the initial stage of damage. Some data suggest that an increase in the number of sarcomeres connected in series, following an initial bout, reduces sarcomere strain during a repeated bout and limits the subsequent damage. It is unlikely that one theory can explain all of the various observations of the repeated bout effect found in the literature. That the phenomenon occurs in electrically stimulated contractions in an animal model precludes an exclusive neural adaptation. Connective tissue and cellular adaptations are unlikely explanations when the repeated bout effect is demonstrated prior to full recovery, and when the fact that the initial bout does not have to cause appreciable damage in order to provide a protective effect is considered. It is possible that the repeated bout effect occurs through the interaction of various neural, connective tissue and cellular factors that are dependent on the particulars of the eccentric exercise bout and the specific muscle groups involved.

Adaptation, Physiological↗
PubMed2000

The adaptive beam-tracing algorithm

The most popular models to predict sound propagation in architectural spaces involve the tracing of rays, images, or beams. Most current beam-tracing methods use conical or triangular beams that may produce overlaps and holes in the predicted sound field. Hence a new method has been developed whereby the shape of reflected beams is governed by the shape of reflecting surfaces so as to produce a geometrically perfect description of the sound propagation for halls with occluding surfaces. The method also facilitates the calculation of diffuse sound propagation by managing the energy transfer from a specular model to a diffuse model. This adaptive beam-tracing method compares well with other methods in terms of speed and accuracy.

Journal Article↗
PubMed1998

Specific sequence changes in the 5'-terminal region of the genome of satellite tobacco mosaic virus are required for adaptation to tobacco mosaic virus.

The genome of satellite tobacco mosaic virus (STMV) adapted to tobacco mosaic virus (TMV), tomato mosaic virus or green tomato atypical mosaic virus consistently had two single base deletions at positions 1 and 61, corresponding to bases A and G, respectively, as compared to the type-strain genome which is naturally adapted to tobacco mild green mosaic virus (TMGMV). Transcript RNAs (STMV(TMV)) from clone pSTMV(TMV) which captured the deletions at positions 1 and 61 were infectious when co-inoculated to tobacco plants with either TMV or TMGMV at infection frequencies of > 90%. Two new STMV variants were created to investigate whether both deletions were essential for adaptation to TMV. These were STMV(TMGMV) deltaA1, which had the A at position 1 (A1) deleted, and STMV(TMGMV) deltaG61, which lacked G61. STMV(TMGMV) deltaA1 was infectious (75% frequency) in the presence of either TMV or TMGMV. Virion RNA of STMV(TMGMV) deltaA1 lost G61 after one infection cycle with TMV. This deletion did not occur in co-infections with TMGMV. STMV(TMGMV) deltaG61, like the clone STMV(TMGMV), was infectious (100% frequency) with TMGMV but TMV did not support this clone. When Nicotiana benthamiana protoplasts were transfected with STMV(TMGMV), STMV(TMGMV) deltaA1 or STMV(TMV), STMV replicated when TMGMV was the helper virus. STMV(TMV) and STMV(TMGMV) deltaA1 replicated in the presence of helper TMV, but STMV(TMGMV) did not, the same result as in whole plants. The deletion of A1 is thus essential for initial STMV adaptation to TMV and the eventual deletion of G61 is a predicted additional change.

Adaptation, Physiological↗
PubMed1996

The time-sequenced adaptive filter for analysis of cardiac arrhythmias in intraventricular electrograms.

Implantable antitachycardia devices rely upon schemes for detecting cardiac arrhythmias which utilize rate and its variations; yet rate parameters often identify nonpathologic tachycardias as potentially dangerous and deliver unwarranted therapy. I have developed a predictive filter based upon the time-sequenced adaptive algorithm to be used as a supplement to rate criteria for detecting and identifying serious arrhythmias. The method does not require a fixed template and is independent of a priori patient information. The algorithm also provides arrhythmia diagnosis immediately at the change in rhythm. Algorithmic parameters were determined based upon a training set of patient data, and performance of the technique was evaluated with a completely new test set of 20 arrhythmia passages. The new algorithm yielded a sensitivity and specificity for ventricular tachycardia of 91% and 82% and for ventricular fibrillation of 71% and 93%. Correlation waveform analysis was used to diagnose the same test set of arrhythmias. It yielded a sensitivity and specificity for ventricular tachycardia of 100% and 67% and for ventricular fibrillation of 50% and 100%.

Adult↗
PubMed2005

Predictive neural networks for gene expression data analysis.

Gene expression data generated by DNA microarray experiments have provided a vast resource for medical diagnosis and disease understanding. Most prior work in analyzing gene expression data, however, focuses on predictive performance but not so much on deriving human understandable knowledge. This paper presents a systematic approach for learning and extracting rule-based knowledge from gene expression data. A class of predictive self-organizing networks known as Adaptive Resonance Associative Map (ARAM) is used for modelling gene expression data, whose learned knowledge can be transformed into a set of symbolic IF-THEN rules for interpretation. For dimensionality reduction, we illustrate how the system can work with a variety of feature selection methods. Benchmark experiments conducted on two gene expression data sets from acute leukemia and colon tumor patients show that the proposed system consistently produces predictive performance comparable, if not superior, to all previously published results. More importantly, very simple rules can be discovered that have extremely high diagnostic power. The proposed methodology, consisting of dimensionality reduction, predictive modelling, and rule extraction, provides a promising approach to gene expression analysis and disease understanding.

Animals↗
PubMed1997

Probed-sinewave paradigm: a test of models of light-adaptation dynamics.

Studies of light adaptation have, in general, employed either aperiodic or periodic stimuli. In earlier work, models originally developed to predict the results from one tradition failed to predict results from the other but the models from the two traditions could be merged to predict phenomena from both. To further test these merged models, a paradigm combining both types of stimuli was used. The threshold for a brief flash (the probe) was measured at various phases on a background that was varied sinusoidally in time. The probe threshold depends upon the phase at which it is presented for all background frequencies used, 0-16 Hz. These threshold variations are not well described by a sinewave; the peak threshold is > 180 deg out of phase with the trough threshold. Further, the positions of the peaks and troughs shift fairly abruptly at background modulations of 4-8 Hz. The difference between the peak and trough thresholds varies as a function of temporal frequency in a manner approximating the temporal contrast sensitivity function. The dc level (mean threshold) does not. The peak-trough difference dominates at low frequencies of background modulation, while the dc level dominates for higher frequencies. Existing models of light adaptation do not predict the key features of the data.

Adaptation, Ocular↗
PubMed1992

Comparing social learning and family systems correlates of adaptation in youths with IDDM.

Evaluated social learning and family systems theoretical models to determine (a) whether illness-specific family relations (based on social learning theory) and general family behaviors (based on family systems theory) relate uniquely to the youths' illness-specific and psychosocial adaptation, and (b) whether these types of family relations covary or whether they represent distinct aspects of family functioning. Participants included 95 youths with insulin-dependent diabetes mellitus (IDDM) and their parents. Positive and supportive family relations (illness-specific family support, general family affection, general family adaptability) as well as conflictual and nonsupportive relations (i.e., illness-specific family nonsupport, general family conflict) were assessed. Results suggest that both illness-specific and general family relations uniquely predict the youths' dietary adherence and general psychosocial adaptation. Because illness-specific and general family relations also covary, broad-based models that include both types of family functioning seem warranted.

Adaptation, Psychological↗
PubMed2004

Testing the goodness-of-fit of a multifaceted preventive intervention for children at risk for conduct disorder.

OBJECTIVE: To determine the importance of parents' global adaptive functioning as a predictor of participation rate and subsequent child social competence outcome in 3 program components of an evidence-based, multifaceted, preventive intervention for at-risk children. METHOD: Families of program children (n = 124, mean age 6.6 years at recruitment) were offered 3 program components that continued for 3 years: a 6-week summer program, a biweekly family program that included concurrent parent and child education and skills training groups, and a flexibly tailored home visitation family support program. We used structural equation modelling to test hypotheses about the effects of parental characteristics on program attendance in each of the program components over 3 years, as well as their relation to children's social competence. RESULTS: Predictors of attendance included child IQ, socioeconomic status (SES), and single-parent status for some components but not others, depending on parents' global adaptive functioning. Predictors of child social competence outcome were mediated by attendance in specific program components and were dependent on parent global adaptive functioning. Some components contributed decisively to social competence outcomes, and others did not, despite subjects' participation. CONCLUSIONS: Common family characteristics (that is, child IQ, SES, and single-parent status) predict program attendance differently, depending on parents' global adaptive functioning. Parents' global adaptive functioning determined whether attendance in specific program components mediated children's social competence. In this preventive intervention, as in clinical practice, only knowledge of the goodness-of-fit between participant characteristics and program attributes can ensure optimum benefit.

Adaptation, Psychological↗
PubMed1997

Relationship-specific social psychological adaptations.

Mainstream social psychology has sought parsimonious explanations of broad general applicability, and has in practice focused on stranger interactions. An evolutionary perspective; however, justifies predicting a rich diversity of relationship-specific social psychological adaptations. The demands of motherhood, fatherhood, mateship, sibship and other relationships are qualitatively distinct, and so, it appears, are the psychophysiological mechanisms that have evolved to deal with them. One window on what distinguishes social relationships is provided by the substance and epidemiology of interpersonal conflicts. Homicides exhibit victim-killer relationship-specific patterns in context, motive and demography, which we discovered only because we adopted an evolutionary psychological perspective. We offer a number of specific hypotheses about possible human psychological adaptations that have yet to be assessed, but are readily derived from consideration of the particular qualities of specific relationship types.

Adaptation, Psychological↗
PubMed1983

Light and dark adaptation in Phycomyces light-growth response.

Sporangiophores of the fungus Phycomyces exhibit adaptation to light stimuli over a dynamic range of 10(10). This range applies to both phototropism and the closely related light-growth response; in the latter response, the elongation rate is modulated transiently by changes in the light intensity. We have performed light- and dark-adaptation experiments on growing sporangiophores using an automated tracking machine that allows a continuous measurement of growth velocity under controlled conditions. The results are examined in terms of the adaptation model of Delbrück and Reichardt (1956, Cellular Mechanisms in Differentiation and Growth, 3-44). The "level of adaptation," A, was inferred from responses to test pulses of light by means of a series of intensity-response curves. For dark adaptation to steps down in the normal intensity range (10(-6)-10(-2) W/m2), A decays exponentially with a time constant b = 6.1 +/- 0.3 min. This result is in agreement with the model. Higher-order kinetics are indicated, however, for dark adaptation in the high-intensity range (10(-2)-1 W/m2). Adaptation in this range is compared with predictions of a model relating changes in A to the inactivation and recovery of a receptor pigment. In response to steps up in intensity in the normal range, A was found to increase rapidly, overshoot the applied intensity level, and then relax to that level within 40 min. These results are incompatible with the Delbrück-Reichardt model or any simple generalizations of it. The asymmetry and overshoot are similar to adaptation phenomena observed in systems as diverse as bacterial chemotaxis and human vision. It appears likely that light and dark adaptation in Phycomyces are mediated by altogether different processes.

Adaptation, Biological↗
PubMed1980

Light-dark adaptation of bacteriorhodopsin in triton-treated purple membrane.

Solubilization of purple membrane with Triton X-100 yields Triton micelles containing bacteriorhodopsin monomers. The absorption maximum of dark-adapted solubilized bacteriorhodopsin is blue-shifted to 549 nm. Light adaption increases the absorbance by 4% and shifts the absorption maximum to 553 nm, i.e., the extent of light adaptation is considerably less than in intact purple membrane. Extraction of dark-adapted bacteriorhodopsin in Triton yields a 13-cis- to all-trans-retinal ratio of 58 : 42 which changes after light adaptation to 38 : 62. It has been shown by Sperling et al. (Sperling, W., Carl, P., Rafferty, Ch.N. and Dencher, N.A. (1977) Biophys. Struct. Mech. 3, 79-94) that light adaptation in intact purple membrane occurs through a branching of the 13-cis photoreaction cycle, so that part of the pigment during each cycle crosses over into the all-trans photoreaction cycle. We explain the decreased extent of light adaptation in solubilized bacteriorhodopsin by assuming a significant back reaction from the all-trans to the 13-cis cycle. This assumption predicts a wavelength dependence of the extent of light adaptation, which is born out by experiment.

Bacteriorhodopsins↗
PubMed2006

Geographical patterns of adaptation within a species' range: interactions between drift and gene flow.

We use individual-based stochastic simulations and analytical deterministic predictions to investigate the interaction between drift, natural selection and gene flow on the patterns of local adaptation across a fragmented species' range under clinally varying selection. Migration between populations follows a stepping-stone pattern and density decreases from the centre to the periphery of the range. Increased migration worsens gene swamping in small marginal populations but mitigates the effect of drift by replenishing genetic variance and helping purge deleterious mutations. Contrary to the deterministic prediction that increased connectivity within the range always inhibits local adaptation, simulations show that low intermediate migration rates improve fitness in marginal populations and attenuate fitness heterogeneity across the range. Such migration rates are optimal in that they maximize the total mean fitness at the scale of the range. Optimal migration rates increase with shallower environmental gradients, smaller marginal populations and higher mutation rates affecting fitness.

Adaptation, Biological↗
PubMed1988

Prediction of early retirement on the basis of a health examination. An 11-year follow-up of 264 male employees in a Swedish pulp and paper company.

In a Swedish pulp and paper company 264 men in the age groups 36, 46, and 56 years underwent a health examination in 1972. An 11-year follow-up in respect of early retirement was performed. On the basis of collected data, five scales to assess work ability were established. The scales were (i) self-assessment of health and work capacity, (ii) the doctor's evaluation of general medical work capacity, (iii) the doctor's assessment of medical adaptation to work, (iv) aerobic work capacity, predicted from a submaximal bicycle test, and (v) work performance, determined from an interview with the subject's nearest superior. Multivariate analysis of the five scales and about 30 other variables showed that general medical work capacity was one of the strongest predictors of early retirement. It was also shown that the medical variables were better predictors of early retirement than the psychological and sociological ones. It was concluded that it is possible to predict early retirement on the basis of a health examination within an occupational health organization.

Adult↗
PubMed1977

Adaptive distortions in the generator potential of semicircular canal sensory afferents.

The generator potential in sensory afferents of frog crista ampullaris was extracellularly recorded from the cut end of the posterior ampullary nerve by means of suction electrodes. A servocontrolled turntable allowed suitable rotatary stimulations. The analysis of the recorded generator potential revealed a different time course from that predicted on the basis of the pendulum model. Adaptation and undershoots in the responses to velocity ramps, steps and sinusoids, were mainly responsible for the deviations, which became very evident only when fairly high acceleration rates were applied. Both adaptation and undershoots were produced presumably by the activation of an electrogenic pump, probably located in nerv terminals contacting the hair cells. In fact, the time course of the generator potential became much more consistent with the predictions from the pendulum model under treatments capable of hindering the ion pump activity.

Acceleration↗