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PubMed1987

The effect of taste adaptation on salivary flow rate and salivary sugar clearance.

To provide an objective measure of the rate of taste adaptation, we measured changes in the flow rate of parotid saliva from 12 subjects while a tastant was infused continuously into their mouths. The tastants employed were sucrose, sodium chloride, and citric acid, each at two different concentrations. With all stimuli, the higher concentration elicited significantly higher initial flow rates, which declined exponentially with time. The half-time for adaptation of flow rate was independent of the nature or concentration of the stimulus and averaged 11.3 sec, which suggests that adaptation follows a single exponential curve. The model of salivary sugar clearance developed by Dawes (1983) predicted that the rate of clearance would be independent of the initial sucrose concentration. However, this model did not take into account the effect of taste adaptation on salivary flow. This process was thus incorporated into the model, which then predicted that the time for clearance would be dependent on the initial sucrose concentration, as found experimentally by Goulet and Brudevold (1984). Hence the process of taste adaptation progressively reduces the stimulated salivary flow rate, which retards the rate of salivary clearance of sugar from the oral cavity.

Adaptation, Physiological↗
PubMed2000

Psychological adaptation of adolescents with immigrant backgrounds.

In the present study, the author examined 3 theoretical perspectives--family values, acculturation strategies, and social group identity--as predictors of the psychological well-being of adolescents from immigrant backgrounds. The 3 perspectives share the view that immigrants' successful adaptation involves the balancing of their heritage culture and the culture of the society of settlement. The participants were 506 adolescents from 4 backgrounds--Vietnamese, Pakistani, Turkish, and Chilean--who were living in Norway. The 3 theoretical perspectives together accounted for between 12% and 22% of the explained variance of mental health, life satisfaction, and self-esteem. The predictive powers of the different perspectives, however, were dependent on which outcome was predicted. On the whole, social group identity showed the strongest predictive power.

Acculturation↗
PubMed2006

Of microbe and man: determinants of Helicobacter pylori-related diseases.

The human gastric pathogen Helicobacterpylori infects the human gastric mucus layer of approximately half of the world's population. Colonization with this bacterium results in superficial gastritis without clinical symptoms, but can progress into gastric or duodenal ulcers, gastric malignancies and mucosa-associated lymphoid tissue-lymphomas. Disease outcome is affected by a complex interplay between host, environmental and bacterial factors. Irrespective of disease outcome, the majority of H. pylori infected individuals remain colonized for life. Changing conditions in the human gastric mucosa may alter gene expression and/or result in the outgrowth of more fit H. pylori variants. As such, H. pylori is a highly flexible organism that is optimally adapted to its host. the heterogeneity in H. pylori populations make predictions on H. pylori-related pathogenesis difficult. In this review, we discuss host, environmental and bacterial factors that are important in disease progression. Moreover, H. pylori adaptive mechanisms, which allow its life-long survival and growth in the gastric mucosa are considered.

Adaptation, Physiological↗
PubMed1998

Functional and adaptive significance of primate pads and claws: evidence from New World anthropoids.

This study tests predicted morphoclines in fingertip morphology among four small-bodied (<1 kg) New World monkeys (Saimiri sciureus, Leontopithecus rosalia, Callithrix jacchus, and Saguinus oedipus) in order to test previous functional and adaptive explanations for the evolution of flattened nails, expanded apical pads, and grasping extremities within the Order Primates. Small-bodied platyrrhines which frequently forage among small-diameter substrates are expected to possess 1) relatively expanded apical pads, 2) well-developed epidermal ridges, 3) distally broad terminal phalanges, and 4) reduced flexor and extensor tubercles compared to those species which use large-diameter arboreal supports more frequently for their locomotor and postural behaviors. Results show that as the frequency of small-branch foraging increases among taxa within this sample, relative distal phalanx breadth also increases but distal phalanx length, height, and flexor tubercle size decrease. Moreover, epidermal ridge development becomes more pronounced as the frequency of small-branch foraging increases. Terminal phalanx breadth and epidermal ridge complexity are both positively correlated with apical pad size. The large, flexible apical pad increases stability of the hand and foot on small-diameter arboreal supports because the pad can contact the substrate in several planes which, in turn, enables the pad to resist disruptive forces from different directions by friction and interlocking (Hildebrand, 1995). The observed morphoclines demonstrate that a gradient in form from claw- to nail-like tegulae exists among these taxa. Thus, the distinction between claw- and nail-bearing platyrrhines is essentially arbitrary. These observations corroborate Cartmill's (1972) functional and adaptive model for the loss of claws in primates: namely, expanded apical pads are required for habitual locomotor and postural behaviors on small-diameter supports whereas claws are more useful for positional behaviors on large-diameter substrates. Finally, results from this study support previous suggestions that the keeled tegulae of callitrichines represent a derived postural adaptation rather than a primitive retention from an ancestral eutherian condition.

Adaptation, Physiological↗
PubMed2006

Motor cortex activation during treatment may predict therapeutic gains in paretic hand function after stroke.

BACKGROUND AND PURPOSE: Functional brain imaging after stroke offers insight into motor network adaptations. This exploratory study examined whether motor cortical activation captured during arm-focused therapy can predict paretic hand functional gains. METHODS: Eight hemiparetic patients had serial functional MRI (fMRI) while performing a pinch task before, midway, and after 2 weeks of constraint-induced therapy. The Wolf Motor Function Test (WMFT) was performed before and after intervention. RESULTS: There was a linear reduction in ipsilateral (contralesional) primary motor (M1) activation (voxel counts) across time. The midpoint M1 Laterality Index anticipated post-therapeutic change in time to perform the WMFT. The change in ipsilateral M1 voxel count (pre- to mid-) correlated with the change in mean WMFT time (pre- to post-). CONCLUSIONS: The relationship between brain activation during treatment and functional gains suggests a use for serial fMRI in predicting the success and optimal duration for a focused therapeutic intervention.

Aged↗
PubMed2006

In-silico prediction and observations of nuclear matrix attachment.

The nuclear matrix is a functionally adaptive structural framework interior to the nuclear envelope. The nature and function of this nuclear organizer remains the subject of widespread discussion in the epigenetic literature. To draw this discussion together with a view to suggest a way forward we summarize the biochemical evidence for the modalities of DNA-matrix binding alongside the in-silico predictions. Concordance is exhibited at various, but not all levels. On the one hand, both the reiteration and sequence similarity of some elements of Matrix Attachment Regions suggest conservation. On the other hand, in-silico predictions suggest additional unique components. In bringing together biological and sequence evidence we conclude that binding may be hierarchical in nature, reflective of a biological role in replicating, transcribing and potentiating chromatin. Nuclear matrix binding may well be more complex than the widely accepted simple loop model.

Algorithms↗
PubMed2002

The evolution of inaccurate mimics.

Instances of strikingly accurate Batesian mimicry (in which a palatable prey organism closely resembles an aversive model) are often cited to illustrate the power of natural selection. Less attention has been paid to those mimics, such as many hoverfly (Syrphidae) mimics of wasps or bees, that resemble their models only poorly. Attempts to provide an adaptive explanation for imperfect mimicry have suggested that what seems a crude resemblance to human observers may appear a close match to predators, or that inaccurate mimics may bear a general resemblance to several different model species. I show here, however, that truly inaccurate mimicry of a single model organism may be favoured over perfect resemblance, by kin selection. Signal detection theory predicts that predators will modify their level of discrimination adaptively in response to the relative frequencies and similarity of models and mimics. If models are rare and/or weakly aversive, greater local similarity of mimics can thus lead to greater attack rates. Where individual mimics are related to others in their vicinity, kin selection will then oppose the evolution of accurate mimicry.

Adaptation, Physiological↗
PubMed2004

Long-term changes in defense styles with psychodynamic psychotherapy for depressive, anxiety, and personality disorders.

OBJECTIVE: This study examined 1) whether patients with chronic and recurrent anxiety and depressive disorders and/or personality disorders demonstrate improvement in their defense styles with long-term dynamic psychotherapy and 2) what the relationship is between defense style change and symptomatic change. METHOD: Measures of defense (Defense Style Questionnaire) and symptoms and functioning were administered at regular intervals over the course of 3-5 years to adults who entered a naturalistic study of long-term psychodynamic psychotherapy. With hierarchical linear regression, the relative contributions of change in variables on the Defense Style Questionnaire to change in other outcome variables were calculated. RESULTS: Those with high initial scores on the maladaptive and self-sacrificing defense styles improved, with effect sizes of 0.80 and 0.67, while overall defensive functioning improved, with an effect size of 0.43. The effect size of the change in score on the Global Assessment of Functioning scale was 0.82. Depressed subjects improved their scores significantly on the Hamilton Depression Rating Scale, and there was a significant improvement in distress, as measured by the SCL-90-R. Changes in score on the Defense Style Questionnaire added substantially to the prediction of variance in these three outcomes above their initial levels. A higher level of defensive functioning also predicted a better self-reported therapeutic alliance. CONCLUSIONS: Defense styles became more adaptive and symptoms improved over time in patients who started with scores in the clinical range. Change in defense style predicts symptomatic change, but causation has not been established.

Adolescent↗
PubMed2004

Cloning and characterization of the histidine kinase gene Dic1 from Cochliobolus heterostrophus that confers dicarboximide resistance and osmotic adaptation.

A gene for a putative two-component histidine kinase, which is homologous to os-1 from Neurospora crassa, was cloned and sequenced from the plant-pathogenic fungus Cochliobolus heterostrophus. The predicted protein possessed the conserved histidine kinase domain, the response regulator domain, and six tandem repeats of 92-amino-acids at the N-terminal end that are found in histidine kinases from other filamentous fungi. Introduction of the histidine kinase gene complemented the deficiency of the C. heterostrophus dic1 mutant, suggesting that the Dic1 gene product is a histidine kinase. Dic1 mutants are resistant to dicarboximide and phenylpyrrole fungicides, and they are sensitive to osmotic stress. We previously classified dic1 alleles into three types, based on their phenotypes. To explain the phenotypic differences among the dic1 mutant alleles, we cloned and sequenced the mutant dic1 genes and compared their sequences with that of the wild-type strain. Null mutants for Dic1, and mutants with a deletion or point mutation in the N-terminal repeat region, were highly sensitive to osmotic stress and highly resistant to both fungicides. A single amino acid change within the kinase domain or the regulator domain altered the sensitivity to osmotic stress and conferred moderate resistance to the fungicides. These results suggest that this predicted protein, especially its repeat region, has an important function in osmotic adaptation and fungicide resistance.

Alleles↗
PubMed2025

Large future genetic diversity losses are predicted even with habitat protection.

Genetic diversity within species is the basis for evolutionary adaptive capacity and has recently been included as a target for protection in the United Nations' Global Biodiversity Framework (GBF). However, we lack large-scale mathematical frameworks to quantify how much genetic diversity has already been lost, let alone to predict future losses under 21st century conservation scenarios. To fill this gap, we developed an area-based spatio-temporal predictive framework of genetic diversity calibrated with population-scale genomic data of 29 plant and animal species. To estimate present genetic diversity loss with our framework, we used species' habitat area and population sizes losses reported in the Living Planet Index, the Red List, and new GBF indicators across 13,808 species for the last 5 decades. Applying our evolutionary framework across these species, we estimate genetic diversity loss lags behind population and habitat area declines, with an estimated current 13-22% &#x3c0; genetic diversity loss. However, we forecast future genetic diversity losses will reach 41-76% even if populations are not further contracted. These results highlight that safeguarding existing habitats is insufficient to maintain the genetic health of species and relying solely on continuous genetic monitoring underestimates lagging long term impacts.

Genetic diversity↗
PubMed1999

Impact of nonlinear heat transfer on temperature control in regional hyperthermia.

We describe an optimization process specially designed for regional hyperthermia of deep-seated tumors in order to achieve desired steady-state temperature distributions. A nonlinear three-dimensional heat transfer model based on temperature-dependent blood perfusion is applied to predict the temperature. Using linearly implicit methods in time and adaptive multilevel finite elements in space, we are able to integrate efficiently the instationary nonlinear heat equation with high accuracy. Optimal heating is obtained by minimizing an integral objective function which measures the distance between desired and model predicted temperatures. A sequence of minima is calculated from successively improved constant-rate perfusion models employing a damped Newton method in an inner iteration. We compare temperature distributions for two individual patients calculated on coarse and fine spatial grids and present numerical results of optimizations for a Sigma 60 Applicator of the BSD 2000 Hyperthermia System.

Algorithms↗
PubMed2006

Assessing aggressiveness quickly and efficiently: the Spanish adaptation of Aggression Questionnaire-refined version.

The assessment of aggressiveness and the prediction of aggression has become a relevant research and applied topic in Psychiatry and Psychology. There have been many attempts in order to get a fast and reliable tool to measure aggression. Buss and Durkee started the pathway, and recently Bryant and Smith developed a tool with an enormous potential, a fast-applicable, reliable and valid test. We herein report a Spanish adaptation of this test and we show that aggressiveness can be measured rapidly, and in a simple, valid and reliable way across different populations. We focus on the discriminant capacity of this test to detect aggressive individuals.

Adolescent↗
PubMed2006

The conversion of variance and the evolutionary potential of restricted recombination.

Genetic recombination is usually considered to facilitate adaptive evolution. However, recombination prevents the reliable cotransmission of interacting gene combinations and can disrupt complexes of coadapted genes. If interactions between genes have important fitness effects, restricted recombination may lead to evolutionary responses that are different from those predicted from a purely additive model and could even aid adaptation. Theory and data have demonstrated that phenomena that limit the effectiveness of recombination via increasing homozygosity, such as inbreeding and population subdivision and bottlenecks, can temporarily increase the additive genetic variance available to these populations. This effect has been attributed to the conversion of nonadditive to additive genetic variance. Analogously, phenomena such as chromosomal inversions and apomictic parthenogenesis that physically restrict recombination in part or all of the genome may also result in a release of additive variance. Here, we review and synthesize literature concerning the evolutionary potential of populations with effectively or physically restricted recombination. Our goal is to emphasize the common theme of increased short-term access to additive genetic variance in all of these situations and to motivate research directed towards a more complete characterization of the relevance of the conversion of variance to the evolutionary process.

Animals↗
PubMed2002

Constraints on the source of short-term motion adaptation in macaque area MT. I. the role of input and intrinsic mechanisms.

Neurons in area MT, a motion-sensitive area of extrastriate cortex, respond to a step of target velocity with a transient-sustained firing pattern. The transition from a high initial firing rate to a lower sustained rate occurs over a time course of 20-80 ms and is considered a form of short-term adaptation. The present paper asks whether adaptation is due to input-specific mechanisms such as short-term synaptic depression or if it results from intrinsic cellular mechanisms such as spike-rate adaptation. We assessed the contribution of input-specific mechanisms by using a condition/test paradigm to measure the spatial scale of adaptation. Conditioning and test stimuli were placed within MT receptive fields but were spatially segregated so that the two stimuli would activate different populations of inputs from the primary visual cortex (V1). Conditioning motion at one visual location caused a reduction of the transient firing to subsequent test motion at a second location. The adaptation field, estimated as the region of visual space where conditioning motion caused adaptation, was always larger than the MT receptive field. Use of the same stimulus configuration while recording from direction-selective neurons in V1 failed to demonstrate either adaptation or the transient-sustained response pattern that is the signature of short-term adaptation in MT. We conclude that the shift from transient to sustained firing in MT cells does not result from an input-specific mechanism applied to inputs from V1 because it operates over a wider range of the visual field than is covered by receptive fields of V1 neurons. We used a direct analysis of MT neuron spike trains for many repetitions of the same motion stimulus to assess the contribution to adaptation of intrinsic cellular mechanisms related to spiking. On a trial-by-trial basis, there was no correlation between number of spikes in the transient interval and the interval immediately after the transient period. This is opposite the prediction that there should be a correlation if spikes cause adaptation directly. Further, the transient was suppressed or extinguished, not delayed, in trials in which the neuron emitted zero spikes during the interval that showed a transient in average firing rate. We conclude that the transition from transient to sustained firing in neurons in area MT is caused by mechanisms that are neither input-specific nor controlled by the spiking of the adapting neuron. We propose that the short-term adaptation observed in area MT emerges from the intracortical circuit within MT.

Action Potentials↗
PubMed2002

Spinal cord injury medicine. 4. Optimal participation in life after spinal cord injury: physical, psychosocial, and economic reintegration into the environment.

UNLABELLED: This learner-directed module on spinal cord injury (SCI) presents a variety of perspectives of the process of personal and environmental adaptation for reintegration. Adaptation is unique to each person and does not predictably follow stages. Models used for understanding the process include biopsychosocial, ICIDH-2 (International Classification of Functioning, Disability and Health), and sector divisions of the environment. Home modification requires home (intermediate environment) evaluation and sociospatial behavioral mapping for planning and appropriation of remodeling in proportion to functional need and use. Options for access to the natural environment include specialized wheelchairs, climbing rigging, kayaks, and sail boats. Sports participation with adaptations is expanding and includes a larger variety of organizations and leagues. Economic needs are effectively anticipated with development of a life care plan. Procreative options to overcome infertility after SCI include vibratory stimulation for ejaculation, intravaginal insemination, intrauterine insemination, in vitro fertilization, and intracytoplasmic sperm injection. Approaches to requests for withdrawal of life-sustaining care include depression screening, pain evaluation, and assistance in accomplishment of person centered goals. Overall, community reintegration after SCI is continually improving because of better acceptance, accessibility, and technology for building adaptations. OVERALL ARTICLE OBJECTIVES: (a) To review models and theories of medical intervention and disablement and (b) to demonstrate their application in rehabilitation practice by designing unique treatment plans that meet patient person-centered goals.

Adaptation, Physiological↗
PubMed1992

Rapid and slow changes in the human cone electroretinogram during light and dark adaptation.

Changes in the response characteristics of the human cone electroretinogram (ERG) during light and dark adaptation were studied in two visually normal subjects. Cone ERG responses were isolated under all adaptation conditions through the use of 31 Hz flicker. To determine the time-course of changes in the cone ERG during adaptation, responses to stimuli of constant luminance were measured repeatedly during 15 min of exposure to an adapting field of 2.0 log cd/m2 and during 30 min of dark adaptation following adapting field termination. In addition, luminance-response functions were obtained before and immediately after adapting field onset, as well as before and immediately after adapting field termination. The results indicate that the human cone ERG is influenced by two major processes. One process has a relatively rapid time-course and serves to reposition the luminance-response function along the luminance axis following changes in ambient light levels. The second process, which has a slow time-course, scales response amplitudes during light and dark adaptation by the same proportion at all stimulus luminances. The results provide a framework for predicting the manner in which the cone ERG will change with alterations in the state of retinal adaptation.

Adaptation, Ocular↗
PubMed1998

Aftereffect of high-speed motion.

A visual illusion known as the motion aftereffect is considered to be the perceptual manifestation of motion sensors that are recovering from adaptation. This aftereffect can be obtained for a specific range of adaptation speeds with its magnitude generally peaking for speeds around 3 deg s-1. The classic motion aftereffect is usually measured with a static test pattern. Here, we measured the magnitude of the motion aftereffect for a large range of velocities covering also higher speeds, using both static and dynamic test patterns. The results suggest that at least two (sub)populations of motion-sensitive neurons underlie these motion aftereffects. One population shows itself under static test conditions and is dominant for low adaptation speeds, and the other is prevalent under dynamic test conditions after adaptation to high speeds. The dynamic motion aftereffect can be perceived for adaptation speeds up to three times as fast as the static motion aftereffect. We tested predictions that follow from the hypothesised division in neuronal substrates. We found that for exactly the same adaptation conditions (oppositely directed transparent motion with different speeds), the aftereffect direction differs by 180 degrees depending on the test pattern. The motion aftereffect is opposite to the pattern moving at low speed when the test pattern is static, and opposite to the high-speed pattern for a dynamic test pattern. The determining factor is the combination of adaptation speed and type of test pattern.

Adaptation, Psychological↗