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PubMed2000

Adaptation to chronic illness and disability and its relationship to perceptions of independence and dependence.

This study extends research on living with chronic physical illness and disability by examining how adaptation processes are associated with different activity domains and how the combination of adaptations and activity domains relate to older adults' perceptions of their independence and dependence, helplessness, emotional reactivity, and coping efficacy. The study investigated the behavioral efforts that 286 older adults with osteoarthritis and/or osteoporosis used to adapt to disability arising from their condition. The findings revealed that adults used a wide range of adaptations, including compensations for loss, optimizing performance, limiting or restricting activities, and gaining help from others. The relative use of each of these adaptations varied across 5 domains of activity: personal care, in-home mobility, community mobility, household activities, and valued activities. Moreover, older adults' perceptions of their independence, dependence, helplessness, emotional reactivity, and coping efficacy varied depending on the domain of activity examined and the type of adaptation used.

Activities of Daily Living↗
PubMed1977

Subjective adaptation to loss of the work role: a longitudinal study.

Both social psychologists and social gerontologists have expressed considerable interest in adaptation to the loss of central life roles. The relationship between retirement and morale, where morale is viewed as an indicator of adaptation, is an example of research within this theoretical framework. In this study, longitudinal data for a select sample of 58 male subjects were used to examine intensively the process of adaptation to retirement. The strongest finding was evidence of high levels of adaptation in the sample as reflected in the overwhelming stability of morale over time. Multiple regression analysis indicated that social resources, particularly marital status and socioeconomic status, condition the relationship between adaptation and retirement. In summary, our analysis supports current suggestions that retirement be viewed as an event which occasions a complex social process of adaptation conditioned by a variety of resource and temporal variables.

Adaptation, Psychological↗
PubMed1994

Optimal nutrition for athletic performance, with emphasis on fat adaptation in dogs and horses.

Four mathematical approaches are proposed to determine optimal ranges of nutrients for specified purposes. For exercise, the diet must provide optimal mixtures of fuels, also optimal amounts of nutrients conducive to a sound structure, a desired power/weight ratio, a water-electrolyte system that resists dehydration and buffers hydrogen ions, a tolerance to the cumulative stress of repetitive competition and tractable attitude. The nutritional strategy of carbohydrate loading risks a variety of abnormalities in dogs and horses. An alternative strategy of fat adaptation (the combination of fat feeding and training) was found to improve aerobic performance in dogs and horses and to spare glycogen utilization and reduce lactate accumulation. Surprisingly, improved anaerobic performance has also been confirmed in fat-adapted horses that have been sprint trained. Fat adaptation increased the blood lactate responses to incremental tests and repeated sprints. Blood lactate accumulation during repeated sprints was affected synergistically by the combination of fat adaptation and sodium bicarbonate supplementation. Fat adaptation in horses appears to facilitate metabolic regulation to achieve power needs, with glycolysis decreasing during aerobic work but increasing during anaerobic work and with blood lactate changes following accordingly. Interactions between fat adaptation and dietary cation-anion balance need further investigation.

Adaptation, Physiological↗
PubMed2025

Genetic Differentiation is Constrained to Chromosomal Inversions and Putative Centromeres in Locally Adapted Populations With Higher Gene Flow.

The impact of genome structure on adaptation is a growing focus in evolutionary biology, revealing an important role for structural variation and recombination landscapes in shaping genetic diversity across genomes and among populations. This is particularly relevant when local adaptation occurs despite gene flow, where clustering of differentiated loci can maintain locally adapted variants by reducing recombination between them. However, the limited genomic resources for nonmodel species, including reference genomes and recombination maps, have constrained our understanding of these patterns. In this study, we leverage the Atlantic silverside-a nonmodel fish with extensive local adaptation across a steep latitudinal gradient-as an ideal system to explore how genome structure influences adaptation under varying levels of gene flow, using a newly available reference genome and multiple recombination maps. Analyzing 168 genomes from four populations, we found a continuum of genome-wide differentiation increasing from south to north, reflecting higher connectivity among southern populations and reduced gene flow at northern latitudes. With increasing gene flow, the number and clustering of FST outlier loci also increased, with differentiated loci found exclusively within large haploblocks harboring inversions and smaller peaks overlapping putative centromeric regions. Notably, sequence divergence was only evident in inversions, supporting their role in adaptive divergence with gene flow, whereas centromeric regions appeared differentiated because of low recombination and diversity, with no indication of elevated divergence. Our results support the hypothesis that clustered genomic architectures evolve with high gene flow and enhance our understanding of how inversions and centromeres are linked to different evolutionary processes.

Gene Flow↗
PubMed2004

Physicochemical evolution and molecular adaptation of the cetacean and artiodactyl cytochrome b proteins.

Cetaceans have most likely experienced metabolic shifts since evolutionarily diverging from their terrestrial ancestors, shifts that may be reflected in the proteins such as cytochrome b that are responsible for metabolic efficiency. However, accepted statistical methods for detecting molecular adaptation are largely biased against even moderately conservative proteins because the primary criterion involves a comparison of nonsynonymous and synonymous substitution rates (dN/dS); they do not allow for the possibility that adaptation may come in the form of very few amino acid changes. We apply the MM01 model to the possible molecular adaptation of cytochrome b among cetaceans because it does not rely on a dN/dS ratio, instead evaluating positive selection in terms of the amino acid properties that comprise protein phenotypes that selection at the molecular level may act upon. We also apply the codon-degeneracy model (CDM), which focuses on evaluating overall patterns of nucleotide substitution in terms of base exchange, codon position, and synonymy to estimate the overall effect of selection. Using these relatively new models, we characterize the molecular adaptation that has occurred in the cetacean cytochrome b protein by comparing revealed amino acid replacement patterns to those found among artiodactyls, the modern terrestrial mammals found to be most closely related to cetaceans. Our findings suggest that several regions of the cetacean cytochrome b protein have experienced molecular adaptation. Also, these adaptations are spatially associated with domain structure, protein function, and the structure and function of the cytochrome bc(1) complex and its constituents. We also have found a general correlation between the results of the analytical software programs TreeSAAP (which implements the MM01 model) and CDM (which implements the codon-degeneracy model).

Adaptation, Physiological↗
PubMed1996

Analysis of DNA damage recovery processes in the adaptive response to ionizing radiation in human lymphocytes.

It has been frequently suggested that the adaptive response to ionizing radiation involves the induction of a chromosomal repair mechanism. Although several lines of evidence favour this assumption, direct proof is lacking. We have chosen to study this question with the help of the comet assay. Lymphocytes from three human donors were given an adapting dose of 0.05 Gy 16 h after mitogenic stimulation and a challenging dose of 2 Gy 5 h thereafter. While a portion of the cells was removed from the cultures for the comet assay, remaining cells were harvested at 52 h culture time and screened for chromosomal aberrations. In some experiments an analysis of cell proliferation was additionally carried out by flow cytometry. In the comet assay a reduced level of initial damage and an increased repair capacity was observed in the adapted + challenged cells; however, this did not result in a reduction of the aberration frequencies. No effect of the adapting dose on cell proliferation was detectable. The analysis of comet distributions revealed that the observed enhanced repair capacity was due to the presence of a subpopulation of slowly repairing cells in the challenged lymphocytes and the lack of such a subpopulation in the adapted + challenged cells. We assume that the slowly repairing cells were quiescent G0 lymphocytes which were removed from the adapted + challenged cell population, probably by apoptotic-like processes.

Adaptation, Physiological↗
PubMed2002

Inducible protective processes in animal systems. X. Influence of nicotinamide in methyl methanesulfonate-adapted mouse bone marrow cells.

The adaptive response is an error-free DNA repair mechanism induced by low levels of physical or chemical agents. Cells pre-exposed to such agents are resistant to genetic damage induced by subsequent treatment at a high dose. There are many reports on such adaptive responses. Recently we have shown the existence of adaptive responses in vivo in the grasshopper Poecilocerus pictus and the mouse and in vitro in human lymphocytes. Different enzymes are implicated in this DNA repair pathway. In an attempt to understand the molecular mechanism of the methyl methanesulfonate (MMS)-induced adaptive response, the present investigations have been undertaken employing nicotinamide, an inhibitor of the DNA repair enzyme poly(ADP-ribose) polymerase (PARP). Pre-, inter- and post-treatments with nicotinamide of MMS-treated mouse bone marrow cells were carried out. The results revealed that there is a significant reduction in the frequency of chromosomal aberrations compared with combined treatment, suggesting an enhancement of the adaptive response by nicotinamide. Further, the results of NAD+ assay in the inter-treatment experiment showed that there is no depletion of NAD+. Thus, it can be stated that PARP is not involved in the MMS-induced adaptive response in mouse bone marrow cells.

Adaptation, Physiological↗
PubMed2002

Prolonged unloading of rat soleus muscle causes distinct adaptations of the gene profile.

Using commercially available microarray technology, we investigated a series of transcriptional adaptations caused by atrophy of rat m. soleus due to 35 days of hindlimb suspension. We detected 395 out of 1,200 tested transcripts, which reflected 1%-5% of totally expressed genes. From various cellular functional pathways, we detected multiple genes that spanned a 200-fold range of gene expression levels. Statistical analysis combining L1 regression with the sign test based on the conservative Bonferroni correction identified 105 genes that underwent transcriptional adaptations with atrophy. Generally, expressional changes were discrete (<50%) and pointed in the same direction for genes belonging to the same cellular functional units. In particular, a distinct expressional adaptation of genes involved in fiber transformation; that is, metabolism, protein turnover, and cell regulation were noted and matched to corresponding transcriptional changes in nutrient trafficking. Expressional changes of extracellular proteases, and of genes involved in nerve-muscle interaction and excitation-contraction coupling identify previously not recognized adaptations that occur in atrophic m. soleus. Considerations related to technical and statistical aspects of the array approach for profiling the skeletal muscle genome and the impact of observed novel adaptations of the m. soleus transcriptome are put into perspective of the physiological adaptations occurring with muscular atrophy.

Adaptation, Physiological↗
PubMed2004

Prismatic adaptation reduces biased temporal order judgements in spatial neglect.

Visuomotor adaptation to rightward-deviating optical-wedge prisms reduces the clinical manifestations of spatial neglect after right hemisphere damage. We investigated whether this beneficial effect of prism adaptation is due to attenuation of the ipsilesional attentional bias that is common in spatial neglect. Five right hemisphere patients performed visual temporal order judgements before and after visuomotor adaptation to 15 degrees rightward-deviating prisms. The magnitude of patients' ipsilesional attentional bias on the temporal order judgement task was significantly reduced following adaptation. By contrast, the temporal order judgements of normal participants did not change following adaptation to either leftward- or rightward-deviating prisms. The findings suggest that prism adaptation helps to rebalance the distribution of spatial attention following right hemisphere damage.

Adaptation, Physiological↗
PubMed1981

Adaptation and the Ives effect.

The Ives effect is the discrepancy between photometric matches made by direct comparison and those made by flicker. When white is used as a standard stimulus, the discrepancy appears to be related to the saturation of the test stimulus. The two methods of photometry involve differences in adaptation. In flicker, the two patches of color are applied to the same retinal area alternately, and the retina becomes adapted to a mixture of the two. In direct comparison, the two colors are applied to separate areas of the retina, each of which becomes adapted to the color falling on it. In this study the state of adaptation is controlled by reversing the bipartite pattern from right to left from reading to reading so that each part of the retina becomes adapted to a mixture of the two colors the same as in flicker. This reversal decreases the Ives effect to an almost negligible amount, indicating that adaptation is a major cause of the effect. Data are also presented for use of yellow and blue standards instead of white.

Adaptation, Ocular↗
PubMed1981

Adaptation to prism-induced heterophoria in subjects with abnormal binocular vision or asthenopia.

In a previous study we investigated how normal subjects adapted to prism-induced heterophoria. In this study we have continued this work by investigating this phenomena in 15 patients with abnormal binocular vision and/or asthenopia. It was found that the majority of subjects lacked or had a deficient adaptation system to base-in and/or base-out prisms, but all except two subjects examined adapted normally to vertical prism. These results suggest that it may be possible to treat the horizontal adaptation system independently from the vertical one. Prism vergences, heterophoria measurements, and the presence of fixation disparity gave little indication of the adaptation ability of the subjects. Symptoms correlated well with adaptation ability.

Accommodation, Ocular↗
PubMed1985

Vergence-adaptive change with a prism-induced noncomitant disparity.

Oculomotor adaptation to a magnified motor field in one eye can occur as a result of the vergence system responding either to (1) the magnification of the field, or (2) via small adaptive fields. This was investigated by monitoring adaptation with the whole oculomotor field magnified in one experiment, and just the central motor field magnified in another experiment. It was shown that adaptation in the periphery occurred at a much slower rate when it was occluded. It is concluded that adaptation in the periphery occurs via adaptive spread from central positions and not via a direct response to the magnification of the oculomotor field.

Adaptation, Physiological↗
PubMed1991

Retinal eccentricity of fusion detail affects vergence adaptation.

Adaptation of tonic vergence ("vergence adaptation" or "prism adaptation") may be produced by sustained accommodative, disparity, or proximal vergence innervation. Phoria measures were used in the present study as indices of tonic vergence adaptation to convergence and divergence stimuli in five subjects. Amblyoscope targets stimulated fusion either over the central or peripheral retina while holding accommodative and proximal stimuli constant. The magnitude and rate of tonic vergence adaptation were greater under the central fusion condition than under the peripheral fusion condition, even though the vergence stimuli were matched between central and peripheral fusion conditions. These results show that tonic vergence adaptation is influenced by the retinal eccentricity of target fusional patterns. However, additional work is required to identify the mechanism(s) underlying this eccentricity effect.

Adaptation, Ocular↗
PubMed1994

Accommodative adaptation in children.

Although accommodative adaptation has been studied extensively in young adult populations, there has been little consideration of this function in children. Accordingly, we examined accommodative adaptation by comparing pre- and post-task measurements of dark accommodation (DA) in children and young adults. DA was assessed objectively before and immediately after a 5-min near-vision task (viewing distance = 20 cm) using an open-field, infrared optometer (Canon Autoref R-1). The study was performed on 15 visually normal children (mean age = 10.1 years) and 10 visually normal young adults (mean age = 25.2 years). No significant difference was observed between the mean values of pre-task DA for the two age groups (children = 1.01 D, adults = 0.88 D). Both groups showed equivalent degrees of accommodative adaptation (approximately 1.0 D), and the rate of regression of post-task DA to the pre-task level was similar for each group. We found a significant positive correlation between the magnitude of adaptation and pre-task DA in children, which was not found in the young adult population. The results indicate that pre-task DA and accommodative adaptation (both in terms of magnitude and rate of decay) are similar in adults and children. This would not support the proposal that the development of nearwork-induced myopia in children is related to short-term variations in accommodative adaptation when compared with young adults.

Accommodation, Ocular↗
PubMedDate not supplied

Repressive adaptive style in children with chronic illness.

OBJECTIVE: The primary objectives of this study were 1) To assess whether previously reported findings of high levels of repressive adaptation in children with cancer are unique to the cancer population or are generally characteristic of children with serious chronic illness and 2) to assess the utility of including a new measure of anger expression in the adaptive style measurement paradigm. METHODS: Measures of defensiveness, trait anxiety, and anger expression were obtained from three groups of children: those with cancer (N = 130), those with chronic illnesses (diabetes, cystic fibrosis, and juvenile rheumatoid disorders; N = 121), and healthy control participants (N = 368). Based on their self-reports, participants were categorized according to the adaptive style paradigm as either high anxious, low anxious, defensive high anxious, or repressor. The prevalence of these categories was compared across groups. RESULTS: Children in the cancer and chronic illness groups both reported significantly higher levels of defensiveness and lower levels of anxiety than did the healthy control participants. Application of the adaptive style paradigm produced a significantly higher percentage of children identified as repressors in the both cancer and chronic illness groups relative to healthy children. Children classified as repressors also reported significantly less expression of anger than did nonrepressors. CONCLUSIONS: An increased prevalence of repressive adaptation is not unique to children with cancer, but may be generally characteristic of children with serious chronic illness. Use of anger in place of anxiety as the repressed affect produced a similar distribution of adaptive styles in the study populations.

Adaptation, Psychological↗
PubMed2006

Short-term adaptation to vertical yoked prisms.

PURPOSE: The purpose of this study was to investigate short-term adaptation to vertical yoked prisms in visually normal subjects as well as to develop normative data for future comparative purposes in patients with acquired brain injury. METHODS: A full-body enclosure containing a calibrated laser pointer was used to assess egocentric localization (i.e., one's perceived sense of "straight ahead") in total darkness. Fourteen visually normal subjects were tested in a counterbalanced manner under both experimental (20 pd base-down) and control (plano or zero power) test conditions with each test condition lasting 1 hour. A rating scale questionnaire was also administered to assess quantitatively subjective adaptation to the yoked prisms. RESULTS: Group mean egocentric localization showed approximately 50% adaptation during the 1-hour test period. Subjective adaptation results were similar. CONCLUSION: The findings suggest that rapid perceptually driven, sensorimotor adaptation occurred as assessed both objectively and subjectively in response to vertical yoked prisms. These results are similar to those found in other experiments involving short-term adaptation to optical rearrangements.

Adaptation, Ocular↗
PubMed2002

Host range and local parasite adaptation.

Parasites may be expected to become locally adapted to their hosts. However, while many empirical studies have demonstrated local parasite adaptation, others have failed to demonstrate it, or have shown local parasite maladaptation. Researchers have suggested that gene flow can swamp local parasite-host dynamics and produce local adaptation only at certain geographical scales; others have argued that evolutionary lags can account for both null and maladaptive results. In this paper, we use item response theory (IRT) to test whether host range influences the likelihood of parasites locally adapting to their hosts. We collated 32 independent experiments testing for local adaptation, where parasites could be assigned as having either broad or narrow host ranges (BHR and NHR, respectively). Twenty-five tests based on BHR parasites had a significantly lower average effect size than seven NHR tests, indicating that studies based on BHR parasites are less likely to demonstrate local parasite adaptation. We argue that this may relate to evolutionary lags during diffuse coevolution of BHR parasites with their hosts, rather than differences in experimental approaches or other confounds between BHR and NHR studies.

Adaptation, Physiological↗
PubMed2003

Costly traumatic insemination and a female counter-adaptation in bed bugs.

Male bed bugs pierce females through the body wall and inseminate directly into the body cavity. It has previously been shown that such traumatic insemination carries costs for females, and sexual conflict regarding the mode of insemination should thus propel male-female coevolution. Since males accumulate sexually antagonistic adaptations, females should evolve counter-adaptations that efficiently abate the costs to females of sexual interactions. Yet, unambiguous experimental evidence for female counter-adaptations is lacking. In bed bugs, the spermalege (a highly modified region of the abdomen where the male usually pierces the female) may represent a female counter-adaptation. We assess the female costs of traumatic insemination by varying the rate of insemination on the one hand, and the rate and mode of piercing trauma to females on the other. Our results show that female mating costs are not extreme-elevated mating rate shortened female lifespan but had no significant effect on lifetime egg production. More importantly, additional abdominal piercing in the spermalege had no effect on females whereas even a very low rate of such piercing outside the spermalege reduced female lifetime egg production by 50%. Thus, females are well counter-adapted to the intrusive mode of insemination exhibited by male bed bugs and the costs of elevated mating are comparable with those in other insects, as predicted by theory. We therefore demonstrate that the spermalege efficiently reduces the direct costs of piercing trauma to females, and hence provide experimental evidence for a female counter-adaptation to a sexually antagonistic male trait.

Adaptation, Biological↗