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PubMedDate not supplied

Reduction of a pattern-induced motion aftereffect by binocular rivalry suggests the involvement of extrastriate mechanisms.

Previous research suggests that plaid-induced motion aftereffects (MAEs) involve extrastriate mechanisms (Wenderoth et al., 1988). There is evidence also that binocular rivalry occurs beyond V1 and that it disrupts the processing of MAEs which are believed to be based upon extrastriate mechanisms (e.g. the spiral MAE) but not MAEs, such as linear MAE induced by a drifting grating, which are thought to arise in striate cortex (Wiesenfelder & Blake, 1990). The logical inference is that binocular rivalry during drifting plaid-induced adaptation should reduce the MAEs which result. We report experiments which confirm this prediction.

Adaptation, Ocular↗
PubMedDate not supplied

Effectiveness of multiple internal standards: deuterated analogues of methylenedioxymethamphetamine, methylenedioxyamphetamine, methamphetamine, and amphetamine.

With the increasing abuse of methylenedioxymethamphetamine (MDMA) thereby requiring analysis, we have undertaken a systematic evaluation on parameters associated with the analysis of MDMA and related compounds, including methylenedioxyamphetamine (MDA), methamphetamine (MA), and amphetamine (AM). Parameters studied included three solid-phase adsorbents, five derivatization reagents, and four deuterated internal standards (IS). This report examines whether differences in quantitation data derived from the use of four ISs (one for each analyte) and two ISs (one for AM and MA, one for MDA and MDMA) are statistically significant. Two types of samples were included in this study. The first type (Type I) included four replicate sets of standard solutions prepared in urine matrix. All analytes (AM, MA, MDA, and MDMA) were included in all samples, and these analytes' concentrations in each set were at five levels (100, 250, 500, 1000, and 2000 ng/mL). Four deuterated analogues (MA-d(8), AM-d(8), MDMA-d(5), and MDA-d(5)) at 500 ng/mL were also included in all solutions. The second type of samples (Type II) included 25 case urine specimens. Most of these specimens contained MA/AM and/or MDMA/MDA. The specific objective of this study is to determine whether the 4-IS approach can indeed generate better quantitative data than a less-costly 2-IS. For Type I samples, where the true concentrations of the analytes are known, two-sample t-test is adapted to examine whether the two sets of prediction errors (i.e., known concentration minus calculated concentration) resulting from the 4-IS and the 2-IS approaches are statistically different. For Type II samples, where the analytes' true concentrations are unknown, one-sample t-test was adapted to determine whether the difference of the quantitation results derived from the 4-IS and the 2-IS approaches is statistically significant. Statistical analysis of quantitation data derived from Types I and II samples indicates that differences in MDA and MDMA concentrations resulting from the use of one (MDA-d(5) or MDMA-d(5)) or two (MDA-d(5) and MDMA-d(5)) are statistically nonsignificant. On the other hand, similar analysis on data derived from Type I samples indicate the use of the analytes' respective deuterated analogues as the ISs appear to generate better quantitative data for AM and MA.

3,4-Methylenedioxyamphetamine↗
PubMed1983

A determinant of bone architecture. The minimum effective strain.

Minimum effective strain (MES), a hypothesis since 1964, has achieved experimental support. The range is about 0.0008-0.002 unit bone surface strain. Strains below the MES apparently do not evoke adaptive architectural bone modeling, but those above it do. As a key property of living lamellar bone and its intermediary organization, MES offers the potential to predict exactly when and where mechanical loads will cause bone architectural adaptations. MES represents a step toward the goal of constructing a specific, predictive, and quantitative theory of the mechanical determinants of skeletal architecture.

Animals↗
PubMed2002

Parental care and adaptive brood sex ratio manipulation in birds.

Under many circumstances, it might be adaptive for parents to bias the investment in offspring in relation to sex. Recently developed molecular techniques that allow sex determination of newly hatched offspring have caused a surge in studies of avian sex allocation. Whether females bias the primary brood sex ratio in relation to factors such as environmental and parental quality is debated. Progress is hampered because the mechanisms for primary sex ratio manipulation are unknown. Moreover, publication bias against non-significant results may distort our view of adaptive sex ratio manipulation. Despite this, there is recent experimental evidence for adaptive brood sex ratio manipulation in birds. Parental care is a particularly likely candidate to affect the brood sex ratio because it can have strong direct effects on the fitness of both parents and their offspring. We investigate and make predictions of factors that can be important for adaptive brood sex ratio manipulation under different patterns of parental care. We encourage correlational studies based on sufficiently large datasets to ensure high statistical power, studies identifying and experimentally altering factors with sex-differential fitness effects that may cause brood sex ratio skew, and studies that experimentally manipulate brood sex ratio and investigate fitness effects.

Age Factors↗
PubMed2004

Beyond average protein secondary structure content prediction using FTIR spectroscopy.

This paper demonstrates that secondary structure information beyond purely protein secondary structure content can be predicted from FTIR (Fourier transform infrared spectroscopy) spectra of proteins with a high degree of accuracy. Both neural networks and adaptive neuro-fuzzy inference systems (ANFISs) were employed to predict helix/sheet segment information. The best results were achieved using ANFISs with fuzzy subtractive clustering based on normalised, compressed amide I data with an average SEP (standard error of prediction, root mean of squared errors) of 1.51. Predictions for average helix/sheet length based merely on the amide I band maximum position in combination with the full-width at half-height resulted in a comparable average SEP of 1.62. This suggests the importance of information on the position and width of the amide I band maximum for the prediction of helix/sheet segment information. Finally, the most promising pattern recognition approaches found in this study were applied to a protein with an as yet unknown x-ray structure: native a1-antichymotrypsin (a1-ACT).

Algorithms↗
PubMed2006

Tests of absolute photorefractoriness in four species of cardueline finch that differ in reproductive schedule.

Species with different reproductive schedules may differ in how they respond to the annual change in photoperiod (the adaptive specialization hypothesis). Seasonally breeding species are predicted to use photorefractoriness to terminate reproduction prior to inclement conditions in autumn and winter, whereas opportunistically breeding species may not exhibit photorefractoriness. We tested for absolute photorefractoriness in four species of cardueline finch that differ in their reproductive schedules: opportunistically breeding red crossbills, flexibly breeding pine siskins, and seasonally breeding Cassin's finches and gray-crowned rosy-finches. Field observations indicated that all four species regress their gonads and begin prebasic feather molt in late summer or autumn. However, exposure to a long day photoperiod in autumn (24 h:0 h L:D) resulted in elevation of gonadotropins and testicular recrudescence in all species except Cassin's finches. Thus, by this criterion, some of the seasonally breeding species tested here did not exhibit absolute photorefractoriness. These results indicate that phylogenetic history needs to be taken into account when considering the adaptive nature of photoperiod response systems.

Analysis of Variance↗
PubMed2004

Digital evolution in time-dependent fitness landscapes.

We study the response of populations of digital organisms that adapt to a time-varying (periodic) fitness landscape of two oscillating peaks. We corroborate in general predictions from quasi-species theory in dynamic landscapes, such as adaptation to the average fitness landscape at small periods (high frequency) and quasistatic adaptation at large periods (low frequency). We also observe adaptive phase shifts (time lags between a change in the fitness landscape and an adaptive change in the population) that indicate a low-pass filter effect, in agreement with existing theory. Finally, we witness long-term adaptation to fluctuating environments not anticipated in previous theoretical work.

Biological Evolution↗
PubMed1996

Beta wave of the scotopic (rod) electroretinogram as a measure of the activity of human on-bipolar cells.

The beta wave of the human electroretinogram (ERG) is widely believed to reflect the activation of on-bipolar cells. However, the shape of the beta wave is also influenced by the activity of other cell types. To assess how the activity of on-bipolar cells is reflected in the human ERG, rod ERG's were recorded in the dark and on the steady fields. Derived P2 responses were obtained by computer subtraction of the receptor contribution to the ERG. The light-adapted derived P2 was shown to have properties similar to those predicted from previous studies of on-bipolar activity. This was also true of the dark-adapted derived P2 if a small (less than 10%) contribution from a negative potential was taken into consideration. The derived P2, and under certain conditions the beta wave, can be used to study rod on-bipolar activity.

Dark Adaptation↗
PubMed1998

Speciation in the lesser galagos.

Species and their origins remain one of the outstanding enigmas of evolutionary biology. Many different views of the problem exist, but few have concrete predictions that open the problem to investigation. This study formalises predictions arising from the Recognition Concept of species (RC) and the Organization Theory of Speciation (OTS), and applies them to the pattern demonstrated by the lesser galago radiation. The RC and OTS are in agreement that one of the primary adaptive responses during animal speciation events involves the system of sexual recognition and reproduction, and indeed the lesser galago taxa show significant divergences in their communication systems relating to specific-mate recognition. On the other hand, only the RC predicts a concomitant adaptive response to the ecological conditions prevailing during speciation, and there are strong indications of shifts in habitat preference among these taxa. The predictions of the RC are supported above those of the OTS.

Adaptation, Physiological↗
PubMed1994

Rapid numerical integration algorithm for finding the equilibrium state of a system of coupled binding reactions.

We have adapted a simple method of numerical integration to predict the equilibrium state of a population of components undergoing reversible association according to the Law of Mass Action. Its particular application is to populations of protein molecules in aqueous solution. The method is based on Euler integration but employs an adaptive step size: the time increment being reduced if it would make the concentration of any component negative and increased while the concentration of any component changes at greater than a specified rate. Parameters of the algorithm have been optimized empirically using a model set of binding equilibria with dissociation constants ranging from 10(-5) M to 10(-9) M. The method obtains the solution to a set of binding equilibria more rapidly than the conventional initial value methods (simple Euler, 4th order Runge-Kutta and variable-step Runge-Kutta methods were tested) for the same accuracy. A computer code in standard C is presented.

Algorithms↗
PubMed2002

Rescue of social motility lost during evolution of Myxococcus xanthus in an asocial environment.

Replicate populations of the social bacterium Myxococcus xanthus underwent extensive evolutionary adaptation to an asocial selective environment (liquid batch culture). All 12 populations showed partial or complete loss of their social (S) motility function after 1,000 generations of evolution. Mutations in the pil gene cluster (responsible for type IV pilus biogenesis and function) were found to be at least partially responsible for the loss of S motility in the majority of evolved lines. Restoration (partial or complete) of S motility in the evolved lines by genetic complementation with wild-type pil genes positively affected their fruiting body development and sporulation while negatively affecting their competitive fitness in the asocial regime. This genetic tradeoff indicates that mutations in the pil region were adaptive in the asocial selective environment. This finding was confirmed by experiments showing that defined deletions of pil gene regions conferred a competitive advantage under asocial conditions. Moreover, an amino acid substitution in an evolved genotype was located in a region predicted by genetic complementation analysis to bear an adaptive mutation.

Biological Evolution↗
PubMed2026

Integrative quantum and systems biology of cancer: From molecular fluctuations to ecological outcomes.

This review treats cancer as a multiscale adaptive system, asks what the framework must predict to be worth adopting, and separates at each scale what the evidence establishes from what is proposed. It is an expert narrative synthesis, not a systematic review, and states the limits of that design. Proton transfer and tautomeric shifts contribute to spontaneous mispairing but do not license claims of directed or non-random mutation: replication timing, three-dimensional chromatin organization, sequence context and known mutagenic processes explain most mutational heterogeneity, leaving any quantum contribution as a residual against that baseline. The Waddington quasi-potential is bounded: outside detailed balance the dynamics are not gradient-derivable and require a probability-flux term. Hysteresis, rate-limited bimodality and return to state after perturbation distinguish an attractor from a transcriptomic cluster. Single-cell karyotype and live-imaging evidence supports whole-genome doubling as an unstable intermediate of heterogeneous origin and context-dependent consequence, not a uniform adaptive strategy. Systems and synthetic biology, virtual cells and digital twins are assessed against benchmarks, not promise. Tissue-scale ecology is reported with the spatial measurements now quantifying it, including evidence that stromal niche construction is not uniformly tumor-supporting. RNA modification is a layer in its own right, showing that the interpretation of a regulatory signal, not its magnitude, is biologically decisive. A dedicated section states the framework's commitments, the observable and evidence at each scale, and what would falsify them, asking what this adds to somatic mutation theory with clonal evolution and plasticity.

Neoplasms↗
PubMed2003

Growth hormone and insulin-like growth factor I of a Euryhaline fish Cottus kazika: cDNA cloning and expression after seawater acclimation.

The four-spine sculpin Cottus kazika is a euryhaline teleost, in which faster growth in seawater (SW) and freshwater (FW) has been reported. In this study, cDNA clones encoding growth hormone (GH) and insulin-like growth factor I (IGF-I) were isolated from this species to examine the involvement of the GH/IGF-I axis in osmotic adaptation. The amino acid sequence of GH predicted from cDNA was highly similar to those of other fish species, 92% to Sparus aurata, 67% to Paralichthys olivaceus, and 63% to Oncorhynchus keta. The predicted sequence of IGF-I was also exhibited high similarity to those of other fishes, 97% to Myxocephalus scorpius, 95% to P. olivaceus, and 81% to O. keta. Tissue distribution of GH and IGF-I mRNA in fish reared in FW and SW was examined by reverse transcription-polymerase chain reaction (RT-PCR). The GH mRNA was detected only in the pituitary gland. The major site of IGF-I mRNA expression was the liver while minor signals were detected in various tissues including the pituitary, gill, fin, heart, spleen, intestine, and kidney. The expression level of GH mRNA in the pituitary was not different between FW- and SW-reared fish. However, the level of IGF-I mRNA in the liver of SW-reared fish was significantly higher than that of FW-reared fish. These results suggest the possible involvement of hepatic IGF-I in SW adaptation of this species.

Adaptation, Physiological↗
PubMed1993

The ability of adolescents to predict future outcome. Part II: Therapeutic enhancement of predictive skills.

The assertion of autonomy, a developmental challenge of adolescence, helps predict the teenager's attitude toward pregnancy and parenthood. Significantly, the ability to predict the future relationship with the infant has direct implications for the achievement of an adaptive outcome. Indeed, the interpersonal outcome of the parent-infant relationship may be predicted by the adolescent's behaviors with her infant. A prospective orientation may offer an important vantage point for improving this relationship. For example, the ability to predict future outcome helps identify potential conflict, such as abuse. When applying a prospective approach during the prenatal period, the adolescent's past relationship with her own mother and her motivations for becoming a parent will be explored in order to predict the future dyadic relationship. For adolescents who are already parents, an assessment of the dyad's contemporaneous interaction may further predict future interpersonal exchange. Moreover, orienting the adolescent parent toward the future may identify areas of potential conflict, as well as foster more adaptive dyadic exchange.

Adolescent↗
PubMed2006

The coral probiotic hypothesis.

Emerging diseases have been responsible for the death of about 30% of corals worldwide during the last 30 years. Coral biologists have predicted that by 2050 most of the world's coral reefs will be destroyed. This prediction is based on the assumption that corals can not adapt rapidly enough to environmental stress-related conditions and emerging diseases. Our recent studies of the Vibrio shiloi/Oculina patagonica model system of the coral bleaching disease indicate that corals can indeed adapt rapidly to changing environmental conditions by altering their population of symbiotic bacteria. These studies have led us to propose the Coral Probiotic Hypothesis. This hypothesis posits that a dynamic relationship exists between symbiotic microorganisms and environmental conditions which brings about the selection of the most advantageous coral holobiont. Changing their microbial partners would allow the corals to adapt to changing environmental conditions more rapidly (days to weeks) than via mutation and selection (many years). An important outcome of the Probiotic Hypothesis would be development of resistance of the coral holobiont to diseases. The following evidence supports this hypothesis: (i) Corals contain a large and diverse bacterial population associated with their mucus and tissues; (ii) the coral-associated bacterial population undergoes a rapid change when environmental conditions are altered; and (iii) although lacking an adaptive immune system (no antibodies), corals can develop resistance to pathogens. The Coral Probiotic Hypothesis may help explain the evolutionary success of corals and moderate the predictions of their demise.

Adaptation, Physiological↗
PubMed1986

Dependence of heart chamber dimensions and dynamics on chamber demands and myocardial properties.

A heart chamber undergoes eccentric hypertrophy in response to a chronic elevation of stroke-displacement demand, and it undergoes concentric hypertrophy in response to a chronic elevation of systolic-pressure demand. Both of these adaptations, which occur in various combinations, involve two myocardial plastic properties, "stretch normalization" and "stress normalization". We have developed a model which predicts dimensions and dynamics of the left ventricle as functions of myocardial properties and of the loads to which the chamber is adapted. The model involves: a stress-normalization rule which describes how myocardial volume depends on average systolic pressure, cavity volumes and the responsiveness of growth to stress; a stretch-normalization rule which describes how the cavity volume of standard stretch relates to average end-diastolic and end-systolic volumes; and a pressure-volume-curve equation giving isometric pressures as functions of cavity volume and myocardial volume relative to standard-stretch cavity volume, and elastic properties including contractility. The model shows how the relations among average dimensions, dynamics and loads depend on myocardial properties, particularly contractility and the growth response to stress. These properties are the main determinants of myocardial performance. In addition to the load adaptations mentioned above, the model predicts eccentric hypertrophy incident to reduced contractility, chronic dilation incident to reduced growth response to stress, myocardial stricture incident to excessive growth response to stress, and concentric hypertrophy (similar to high-pressure adaptation) incident to deposition of inert material. It allows some refinements in the evaluation of myocardial performance and in the evaluation of the abnormal properties responsible for abnormal performance.

Adaptation, Physiological↗
PubMed1995

[Predictive value of Doppler ultrasound findings in twin pregnancies].

In a prospective study we investigated 100 twin pregnancies in order to assess the predictive value of doppler-sonographic measurements regarding the pregnancy outcome. We used the pulsatility index of the uterine arteries, the umbilical artery, the fetal aorta thoracica and the fetal middle cerebral artery. The measurements were obtained at various gestational ages between 24 and 32 weeks. Significant differences between unselected twin pregnancies and normal single pregnancies were not found. Moreover, there is no relation between the severity of an impaired perfusion and an adverse outcome of the pregnancy. The prediction of fetal distress (hypoxia, preterm birth, poor fetal growth, acidosis, and disturbed neonatal adaption) with doppler-score has a sensitivity of 25% and a positive predictive value of 63%. From this rather insufficient result we conclude that doppler screening in unselected twin pregnancies hardly proves to be useful.

Birth Weight↗
PubMedDate not supplied

Adapting to diabetes: metabolic control and psychosocial variables.

The purpose of this study was to examine the influence of hardiness, self-efficacy, coping style and psychosocial adaptation to illness on the metabolic control of insulin dependent and non-insulin dependent subjects. After adjustment for age, gender and diabetes type the best predictors for insulin dependent diabetics were found to be hardiness and psychosocial adjustment, and for non-insulin dependent diabetics, psychosocial adjustment alone. No interaction effect was found between the variables. Self-efficacy and coping skills were not found to predict metabolic control.

Adaptation, Psychological↗