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PubMed1983

Short-term adaptation to the induced effect.

The short-term adaptation (1-4 h) to the induced effect was investigated on four subjects. A 4% meridional afocal magnifier axis 180 was worn before one eye in normal binocular conditions, which produced vertical retinal-image disparity. In certain circumstances this vertical disparity will give rise to the induced effect, i.e. a surface in the objective frontal plane will appear to be rotated around a vertical axis with the apparently closer edge on the same side as the magnifying lens. Adaptation, which is considered as a reduction in the induced effect over time, was measured with a modified Howard - Dolman apparatus. Both the maximal induced effect and the maximal short-term adaptation occurred within the first 30 min and ranged from 40 to 85%. The final level of short-term adaptation to the induced effect ranged from 20 to 45%. These results suggest a rapid recalibration of binocular depth perception by higher-level perceptual centers.

Adaptation, Ocular↗
PubMed1986

Energy metabolism in largemouth bass (Micropterus floridanus salmoides) from stressed and non-stressed environments: adaptations in the secondary stress response.

White muscle proteins, carbohydrates, lipids, adenylates, phosphagen and the AEC, (adenylate energy charge) were measured in bass inhabiting stressful and non-stressful environments. Within an environment, in June stressed bass had higher carbohydrates, while non-stressed bass had lower ATP, total adenylates and AEC. Comparisons between environments revealed: non-stressed bass had higher ATP/ADP and AEC's in May, CrP/ATP in June, and protein in July; while stressed bass had higher carbohydrate in June and lipid in July. Other metabolites varied insignificantly. AEC's of both groups were within the optimal range indicating physiological compensation (adaptation) of energy metabolism (secondary stress response) occurred in bass inhabiting the stressful environment.

Acclimatization↗
PubMed1997

Propagation of bird acoustic signals: comparative study of starling and blackbird distress calls.

Previous works have demonstrated that the information supported by a bird distress call is encoded both by the energy distribution among harmonics and the temporal evolution of the frequency modulation. In the present study, using these parameters, we compared long-range information transfer in a dense vegetation environment between the starling Sturnus vulgaris and the blackbird. Turdus merula distress calls. It appears that excess attenuation of high frequencies (higher than 4 kHz) after a long-range propagation is responsible for modifications in distress call spectra. The energy of propagated signals tends to be concentrated in a 1.5-4-kHz bandwidth whatever the initial spectrum. Owing to its broad spectrum (0.8-7 kHz), the starling distress call is greatly modified. On the contrary, owing to a narrower spectrum (2-5.5 kHz), the blackbird distress call is relatively preserved. The blackbird distress call appears to be well-adapted to long-range transmission in an environment with dense vegetation. In contrast, the starling distress call is far more easily degraded by propagation. Nevertheless, frequency modulation of the starling call is preserved and message decoding remains possible even if message reliability may diminish. This result is examined from an etho-ecological point of view, taking into account both habitat and social structure of both birds.

Acoustic Stimulation↗
PubMed2000

Reconstruction of the Achilles tendon and overlying soft tissue using antero-lateral thigh free flap.

Reconstruction of combined loss of the Achilles tendon and overlying soft tissue was performed using an antero-lateral thigh free flap in three patients. The cutaneous portion is used to cover the open wound, and a piece of fascia lata is utilised to replace the missing segment of the Achilles tendon. The skin defect ranged from 5 x 2.5 to 7 x 5 cm, and the tendon loss measured from 3.5 to 5.5 cm in length. All of the patients showed satisfactory functional results with a follow-up period from 3 to 9 months. The advantages of the procedure are that: it is a single-staged operation; it promotes rapid healing of the tendo Achilles since the tendon substitute is well vascularised; it is adaptable to a wide range of defect sizes and shapes; it can be performed in the supine position without the need for postural change; and it can restore good contour and causes minimal morbidity at the donor site.

Achilles Tendon↗
PubMed1995

Mechanism of photosensory adaptation in Halobacterium salinarium.

Phototaxis in Halobacterium salinarium is the result of an interplay of sensory rhodopsin excitation and adaptation to the stimulus background. Adaptation to orange light, received by sensory rhodopsin I was probed by measuring the behavioral response of cells to a step-like decrease in intensity. Cells were able to adapt to an intensity range of more than four orders of magnitude. The data were analysed on the basis of theoretical fluence rate response relationships calculated from the photocycle kinetics of the complex of sensory rhodopsin I with its transducer HtrI. Independent of the stimulus background, the cellular response was shown to be a function of the absolute number of photoreceptor complex molecules turned over by the light stimulus. Receptor deactivation was identified as the underlying mechanism of adaptation and was sufficient to account for the experimental results. We suggest that reversible methylation of the transducer protein HtrI provides the chemical mechanism of sensory adaptation in H. salinarium and also explains the different sensitivity of the cells to orange and UV light.

Adaptation, Physiological↗
PubMed2003

Comparison of family stresses, strengths, and outcomes after trauma and surgery.

This study aimed to compare family stresses, strengths, and outcomes after motor vehicle crashes, gunshot wounds, and coronary artery bypass graft surgery. A multivariate descriptive design based on the resiliency model of family stress was used. A convenience sample of 127 family members participated within 2 days of admission to the intensive care unit. Family stresses were measured using the Family Inventory of Life Events and the Acute Physiology, Age, and Chronic Health Evaluation Scale (APACHE III). Family strengths were measured by the Family Hardiness Index and the Family Crisis Oriented Personal Evaluation Scale. Family outcomes were measured by the Family Member Well-Being Index and the Family Adaptation Scale. Family members ranged in age from 18 to 80 years (Mean, 42 years). Most of the participants in the study were women (64%) with previous intensive care unit experience (83%). The patients ranged in age from 19 to 78 years (Mean, 44 years). Multivariate analysis of variance was used to control for group differences in family member age, education, and income along with patient age and race. The results indicated that family members of patients who have experienced motor vehicle crashes, gunshot wounds, or coronary artery bypass graft surgery reported no significant differences in family strengths of hardiness and family outcomes of well-being and adaptation. However, families of patients with gunshot wounds reported significantly more stress (F = 7.94; P< 0.01) and less use of coping strategies (F = 4.33; P< 0.01) than families of patients who have experienced motor vehicle crashes or coronary artery bypass graft surgery. Interventions that address family stress and develop or mobilize coping are needed for selected families after admission of a family member to the intensive care unit.

Accidents, Traffic↗
PubMed2005

Communities adjust their temperature optima by shifting producer-to-consumer ratio, shown in lichens as models: II. Experimental verification.

The community adaptation hypothesis [7] predicts that lichens, simple communities of microorganisms, can adapt to a wide range of thermal regimes by regulating the ratio of primary producers (algae) and consumers (fungi): R(p/c). To test this hypothesis, we determined R(p/c) values by image analysis of cross sections of herbarium specimens of the lichen Cladina rangiferina, which is widely distributed between the Arctic and the tropics. We found that R(p/c) for C. rangiferina increases with summer temperature by more than one order of magnitude, consistent with the hypothesis. To assess the ecological significance of community adaptation (R(p/c) regulation), other adaptive mechanisms (e.g., photobiont substitution, genetic adaptation, and photosynthetic acclimation in North American Cladina spp.) were studied. Laboratory investigations with algae and fungi isolated in culture from live specimens suggested that the role of these mechanisms is relatively minor and cannot account for the high degree of lichen adaptability.

Adaptation, Physiological↗
PubMed2006

A whole genome long-range haplotype (WGLRH) test for detecting imprints of positive selection in human populations.

MOTIVATION: The identification of signatures of positive selection can provide important insights into recent evolutionary history in human populations. Current methods mostly rely on allele frequency determination or focus on one or a small number of candidate chromosomal regions per study. With the availability of large-scale genotype data, efficient approaches for an unbiased whole genome scan are becoming necessary. METHODS: We have developed a new method, the whole genome long-range haplotype test (WGLRH), which uses genome-wide distributions to test for recent positive selection. Adapted from the long-range haplotype (LRH) test, the WGLRH test uses patterns of linkage disequilibrium (LD) to identify regions with extremely low historic recombination. Common haplotypes with significantly longer than expected ranges of LD given their frequencies are identified as putative signatures of recent positive selection. In addition, we have also determined the ancestral alleles of SNPs by genotyping chimpanzee and gorilla DNA, and have identified SNPs where the non-ancestral alleles have risen to extremely high frequencies in human populations, termed 'flipped SNPs'. Combining the haplotype test and the flipped SNPs determination, the WGLRH test serves as an unbiased genome-wide screen for regions under putative selection, and is potentially applicable to the study of other human populations. RESULTS: Using WGLRH and high-density oligonucleotide arrays interrogating 116 204 SNPs, we rapidly identified putative regions of positive selection in three populations (Asian, Caucasian, African-American), and extended these observations to a fourth population, Yoruba, with data obtained from the International HapMap consortium. We mapped significant regions to annotated genes. While some regions overlap with genes previously suggested to be under positive selection, many of the genes have not been previously implicated in natural selection and offer intriguing possibilities for further study. AVAILABILITY: the programs for the WGLRH algorithm are freely available and can be downloaded at http://www.affymetrix.com/support/supplement/WGLRH_program.zip.

Algorithms↗
PubMed1976

Distribution of 3':5'-cyclic AMP and 3':5'-cyclic GMP in rabbit retina in vivo: selective effects of dark and light adaptation and ischemia.

By use of highly sensitive radioimmunoassays, 3':5'-cyclic AMP (cAMP) and 3':5'-cyclic GMP (cGMP) were measured in individual layers of light- and dark-adapted rabbit retinas, and the effects of ischemia were determined. In light-adapted retinas, cGMP levels ranged 50-fold, with over 90% of the total concentrated in the photoreceptor cells. The layer of outer segments contained 95 mumol/kg of dry weight, or three times the concentration present in the remainder of the photoreceptor cell layers. By contrast, levels of cAMP varied only 4-fold; the lowest level (6 mumol/kg of dry weight) was found in the outer segment layer and the highest level (22 mumol/kg of dry weight) in the inner segment layer of the photoreceptor cells. Dark adaptation elevated cGMP levels only in retinal layers containing photoreceptor cells, and the greatest proportional increase was observed in the synaptic layer of photoreceptor cells. Dark adaptation also caused increases of cAMP that were restricted to the outer plexiform and outer nuclear layers. Ischemia lowered cGMP levels, but only in retinal layers containing photoreceptor cells, and elevated cAMP levels, primarily in the inner layers of the retina. The effects of ischemia were greater in the dark-adapted than in light-adapted retinas. These results indicate that cGMP and cAMP levels in retina are influenced by the light adaptational state, that ischemia markedly modifies these processes, and that the effects of both light exposure and ischemia are regionally selective.

Animals↗
PubMed2006

Quantification of immunohistochemistry--issues concerning methods, utility and semiquantitative assessment II.

Immunohistochemistry is entering its fourth decade of use on formalin-fixed paraffin-embedded tissues. Over this period the method has evolved to become a major part of the practice of diagnostic surgical pathology worldwide. From the beginning immunohistochemistry has been adapted to provide a range of markers of cell lineage and tissue type, with particular application to the diagnosis and classification of tumours. In this modality immunohistochemical methods were employed simply as 'special stains', the results of which were evaluated qualitatively by the pathologist, as for any other stain. More recently, attention has shifted to the demonstration of prognostic markers in tumour cells, driven by the advent of molecular biology and the discovery of numerous regulatory molecules, coupled with manufacture of the corresponding specific antibodies. Immunohistochemistry has rapidly adapted to this new use, but in so doing the demand for quantification has become paramount; it is no longer enough that the 'stain' is there; rather it is a question of 'How much is there?'. This review explores the limitations of immunohistochemistry when employed in a semiquantitative mode, and explores the possibility of fulfilling the full potential of immunohistochemistry, as a true quantitative immunoassay applied in a tissue section environment.

Biomarkers↗
PubMed1999

Adaptive response and dose-response plateaus for initiation in a state-vector model of carcinogenesis.

PURPOSE: To investigate whether it is possible to explain dose-response plateaus for in-vitro X-ray irradiation of different cell lines with radioprotective mechanisms such as radiologically induced expression of scavengers and repair enzymes. MATERIALS AND METHODS: A biomathematical model was developed based on a previous state-vector model. New features of the model are a mathematical description of enhanced repair and radical scavenging as a result of irradiation. RESULTS: The model produces a plateau in the dose-response for in-vitro tranformations between 0.5 and 1 Gy and for chromosome aberrations and it predicts an inverse-fractionation effect within a selected range of doses. CONCLUSIONS: Adaptive response mechanisms within a state-vector model provide a coherent explanation of the dose-response characteristics for in-vitro transformations and chromosomal aberrations. These results suggest the need for new experimental studies described in the paper.

Adaptation, Biological↗
PubMed2005

Macronutrients as sources of food energy.

This background paper considers the extent to which the development of new recommendations for dietary energy requirements needs to account for the macronutrient (fat, carbohydrate, protein and alcohol) profiles of different diets. The issues are discussed from the dual perspectives of avoiding under-nutrition and obesity. It is shown that, in practice, human metabolic processes can adapt to a wide range of fuel supply by altering fuel selection. It is concluded that, at the metabolic level, only diets with the most extreme macronutrient composition would have any consequences by exceeding the natural ability to modify fuel selection. However, diets of different macronutrient composition and energy density can have profound implications for innate appetite regulation and hence overall energy consumption.

Adaptation, Physiological↗
PubMed1990

[The temperature dependence of the respiration and phospholipid content of the mitochondria in the organs of heat-adapted rats].

A shift of breaking point to higher temperatures was illustrated on Arrhenius plots in kidney, liver and heart mitochondria of heat-adapted rats on 4.1, 2.7, 2.4 degrees C respectively. Q10 mitochondrion respiration fall in adapted animals in a range of 26-36 degrees C was indicative of temperature compensation. It was shown the elevation of phospholipid plasmalogen form content in heart and kidney mitochondria; as well as saturated fatty acids content in liver mitochondria. Structure and function changes were suggested to be the basic point of elevation of mitochondrion functional ability at high ambient temperature.

Adaptation, Physiological↗
PubMedDate not supplied

Effect of ambient illumination on the spatial properties of the center and surround of Y-cell receptive fields.

The primary goal of this study was to expand the description of the filtering properties of the Y-cell receptive field, by quantitatively characterizing the spatial filtering properties of the receptive field's center-and-surround components as a function of adapting light level. A range of more than five orders of magnitude in retinal illuminance were covered, including the vast majority of the cat's functional range of vision. Recordings were taken from optic tract fibers of Y cells in cats under general anesthesia. Sinusoidal gratings and a stimulus designed to selectively probe the properties of the surround mechanism were used. The cells' responses to these stimuli were fit to a Gaussian center-surround receptive-field model, in which six parameters define the properties of the center and surround. Fits were made independently to data collected at each light level and changes in the values of the model's parameters with illuminance are reported. A set of equations that summarize the changes in parameter values is given. From these summary equations, reasonable estimates of the parameters' values can be determined across a wide range of illuminances. Hence, a quantitative model of the spatial properties of the center and surround of the Y-cell receptive field can now be derived from these equations for most of the levels of retinal illuminance experienced by a Y cell. The consistency between the description provided by our equations and results from earlier work is considered.

Animals↗
PubMed2001

A novel filter bank for biotelemetry.

In a multichannel biotelemetry system, signals taken from a patient are distributed along the available frequency range (bandwidth) of the system through frequency-division-multiplexing, and combined into a single composite signal. Biological signals that are limited to low frequencies (below 10 Hz) modulate the frequencies of respective sub-carriers. Other biological signals are carried in amplitude-modulated forms. It is recognized that recovering original signals from a composite signal at the receiver side is a technical challenge when a telemetry system with narrow bandwidth capacity is used, since such a system leaves little frequency spacing between information channels. A filter bank is therefore utilized for recovering biological signals that are transmitted. The filter bank contains filter units comprising switched-capacitor filter integrated circuits. The filters have two distinct and opposing outputs (band-stop (notch) and band-pass). Since most biological signals are at low frequencies, and modulated signals occupy a narrow band around the carrier, notch filters can be used to efficiently stop signals in the narrow frequency range. Once the interim channels are removed, other channels become well separated from each other, and band-pass filters can select them. In the proposed system, efficient filtering of closely packed channels is achieved, with low interference, from neighboring channels. The filter bank is applied to a system that carries four biological signals and a battery status indicator signal. Experimental results reinforce theoretical predictions that the filter bank successfully de-multiplexes closely packed information channels with low crosstalk between them. It is concluded that the proposed filter bank allows utilization of cost-effective multichannel biotelemetry systems that are designed around commercial audio devices, and that it can be readily adapted to a broad range of physiological recording requirements.

Biomedical Engineering↗
PubMed1999

Disposable microbore high-pressure liquid chromatography columns for protein and peptide separations.

A range of high-performance liquid chromatography (HPLC) columns with internal diameters of 0.25 to 1.8 mm have been constructed by securing glass or plastic tubing into standard HPLC fittings. These were packed with chromatographic materials chosen for operation at moderate pressures with high flow rates. These columns were shown to be effective in a conventional HPLC instrument for peptide and protein separations in reverse-phase mode and for proteins in ion-exchange and size-exclusion modes. The simple construction and low cost of these microbore columns allow them to be considered as disposable. Using only small amounts of any type of packing material, they have the flexibility to be adapted to a wide range of analytical and micropreparative separations.

Chromatography, Gel↗
PubMed2002

Adaptive multiscale principal components analysis for online monitoring of wastewater treatment.

Fault detection and isolation (FDI) are important steps in the monitoring and supervision of industrial processes. Biological wastewater treatment (WWT) plants are difficult to model, and hence to monitor, because of the complexity of the biological reactions and because plant influent and disturbances are highly variable and/or unmeasured. Multivariate statistical models have been developed for a wide variety of situations over the past few decades, proving successful in many applications. In this paper we develop a new monitoring algorithm based on Principal Components Analysis (PCA). It can be seen equivalently as making Multiscale PCA (MSPCA) adaptive, or as a multiscale decomposition of adaptive PCA. Adaptive Multiscale PCA (AdMSPCA) exploits the changing multivariate relationships between variables at different time-scales. Adaptation of scale PCA models over time permits them to follow the evolution of the process, inputs or disturbances. Performance of AdMSPCA and adaptive PCA on a real WWT data set compared and contrasted. The most significant difference observed was the ability of AdMSPCA to adapt to a much wider range of changes. This was mainly due to the flexibility afforded by allowing each scale model to adapt whenever it did not signal an abnormal event at that scale. Relative detection speeds were examined only summarily, but seemed to depend on the characteristics of the faults/disturbances. The results of the algorithms were similar for sudden changes, but AdMSPCA appeared more sensitive to slower changes.

Algorithms↗
PubMed1993

How much does illuminant color affect unattributed colors?

Does the light coming from a surface (as opposed to the surface color) appear the same after adaptation to a new illumination as it did before the illumination changed? Many answers have been proposed over the past century, but all have been unsatisfactory. The main measurement problem is to provide a comparison stimulus that is unaffected by the adaptation being tested. My observers used a mental standard. Under 4000-, 6500-, and 10,000-K adaptations (the extremes and the average of daylight) they produced on a CRT unique hues with a constant saturation that was memorized during training. The main evaluation problem is how to determine the theoretical chromaticity shifts that represent illumination invariance for comparison with the data. Like most previous investigators, I used light sources rather than actual surfaces and illuminants. Using a new technique, I determined theoretical surfaces that would have unique hues under the test illuminants. Using Cohen's basis vectors, I derived theoretical reflectances that under 6500 K would produce the chromaticities that the observer chose as unique hues. The chromaticities of those same reflectances under 4000 and 10,000 K are theoretical points representing illuminants-invariant appearance of the light coming from the surfaces. Even for this small range of illuminants the adaptive shifts were too small for invariance, i.e., the appearance of the light was different even after full adaptation. This result sharpens the question of the basis for humans' concept of color as a stable property of surfaces.

Adaptation, Ocular↗