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PubMed1996

Psychological reactions during polar expeditions and isolation in hyperbaric chambers.

BACKGROUND: Psychological data from environments that are considered as analog to space was collected from 68 subjects; 18 in hyperbaric chambers, 16 in polar expeditions, and 34 on Arctic stations. The objective was to identify psychological reactions expected in different phases of spaceflights and examine personality variables associated with superior adaptation. METHOD: Helmreich Personality Characteristic Inventory was administered before the isolation. Adaptation to the environment was assessed through a questionnaire once a week. RESULTS: Crews in hyperbaric chambers indicated a steady increase in coping over the isolation. Polar expeditions members reported high aggressiveness and anxiety in the first quarter and an increase in homesickness over time. A personality characterized by strong expressiveness and instrumentality ("the right stuff") predicted superior adaptation in hyperbaric chambers. CONCLUSION: The data suggest that isolation in hyperbaric chambers and polar expeditions should be considered as models for different aspects of the space environment.

Adaptation, Psychological↗
PubMed1992

Predictability and reliability of hearing aid benefit measured using the PHAB.

This investigation explored the extent to which self-assessed hearing aid benefit measured by the Profile of Hearing Aid Benefit (PHAB) could be predicted from adaptation to hearing loss and/or from communication difficulties reported without amplification. Adaptation to hearing loss was measured using 13 scales of the Communication Profile for the Hearing Impaired (CPHI). These were combined to produce three composite CPHI scores. Results from 58 experienced hearing aid wearers indicated that benefit was significantly related to magnitude of unaided difficulties for all seven PHAB subscales. In addition, one of the three composite CPHI scores contributed to benefit prediction for the two sound perception subscales of the PHAB. Test-retest reliability of PHAB subscale scores was evaluated for 28 subjects using correlations and difference distributions. Reliability was found to be consistent with previous studies but modest. Critical differences were large compared with the anticipated size of benefit differences due to, for example, different hearing aid prescriptions. It is concluded that the PHAB is best suited for group research: when used for individual subjects, the PHAB may not be sensitive enough to detect important differences between hearing aid conditions.

Adaptation, Psychological↗
PubMed2006

Rotation rate and duration effects on the somatogyral illusion.

INTRODUCTION: Aviation spatial disorientation mishaps remain a concern, especially due to their fatality rate. Some of the most insidious disorientations are due to vestibular stimuli in the absence of visual cues. A category of such disorientations are known as somatogyral illusions. METHODS: To determine the effects of spin rate and duration on the perception of the somatogyral illusion, we examined the subjective response of pilots and non-pilots to rotation around the yaw axis in a flight simulator in a manner that would mimic two vestibular illusions found in flight: the washout of the semi-circular canals following sustained turns, and the illusory counter-rotation following return to straight and level flight. There were 29 subjects (14 pilots) who were seated blindfolded in a flight simulator which accelerated to constant plateau rotation rates of 20, 70, and 120 degrees x s(-1) and then decelerated to stationary; plateaus were 10, 20, or 40 s. Subjects reported 1) the time when the perception of rotation ceased (i.e., the subjective time until washout was reached); 2) the relative magnitude of the counter-rotation experienced; and 3) the time until the perception of counter-rotation ceased. Subjects also manipulated a slider to provide a continuous subjective measure of their experience of rotation. RESULTS: The two time measures increased with increases in both the duration and magnitude of the spin. The increase in perceived washout time with spin rate was non-linear (geometric). There was an interaction between spin duration and spin rate on the experience of illusory counter-rotation magnitude such that at low rates, spin duration had no effect, but its effect increased at faster rates. The time constant of adaptation of the semicircular canals was estimated to be 8.3 s. DISCUSSION: The effects were validated against a model of semicircular canal and cupola adaptation, which predicted the data with high accuracy. Pilots and non-pilots did not differ in their illusory experience.

Adaptation, Physiological↗
PubMed2000

Prevalence, predictive factors, and screening for psychologic distress in patients with newly diagnosed head and neck cancer.

BACKGROUND: High levels of distress are a concern regarding patients with head and neck cancer. Early detection of and intervention for such distress are needed to predict patients' adaptation to treatment or rehabilitation, but few studies have investigated the detection of their distress in a patient population of significant size. METHODS: The authors examined 107 consecutive patients with head and neck cancer to assess their psychologic distress (adjustment disorders or major depression) or other psychiatric problems by structured psychiatric interview before the initial cancer treatment. They also evaluated predictive factors for psychologic distress and assessed the ability of a self-rating questionnaire (Hospital Anxiety and Depression Scale, HADS) to screen for distress. RESULTS: Of 107 subjects, 18 (16.8%) had an adjustment disorder or major depression. Thirty-six (33.6%), 7 (6. 5%), and 35 (32.7%) met criteria for alcohol dependence, alcohol abuse, and nicotine dependence, respectively. Logistic regression analysis revealed that having advanced stage cancer (odds ratio, 5. 77; 95% confidence interval [CI], 1.41-39.7; P = 0.03) and living alone (odds ratio, 4.83; 95% CI, 1.04-22.2; P = 0.04) were significantly associated with having psychologic distress. The optimal cutoff point for the HADS screening for psychologic distress was 15. This cutoff point gave 72.2% sensitivity and 81.4% specificity. CONCLUSIONS: Head and neck cancer patients who have advanced disease or live alone should be assessed so that psychologic distress can be detected and intervention made. HADS is a useful clinical instrument to screen for their distress.

Adjustment Disorders↗
PubMed2006

Adaptive-filtering of trisomy 21: risk of Down syndrome depends on family size and age of previous child.

The neonatal incidence rate of Down syndrome (DS) is well-known to accelerate strongly with maternal age. This non-linearity renders mere accumulation of defects at recombination during prolonged first meiotic prophase implausible as an explanation for DS rate increase with maternal age, but might be anticipated from chromosomal drive (CD) for trisomy 21. Alternatively, as there is selection against genetically disadvantaged embryos, the screening system that eliminates embryos with trisomy 21 might decay with maternal age. In this paper, we provide the first evidence for relaxed filtering stringency (RFS) to represent an adaptive maternal response that could explain accelerating DS rates with maternal age. Using historical data, we show that the proportion of aberrant live births decrease with increased family size in older mothers, that inter-birth intervals are longer before affected neonates than before normal ones, and that primiparae exhibit elevated levels of DS incidence at higher age. These findings are predicted by adaptive RFS but cannot be explained by the currently available alternative non-adaptive hypotheses, including CD. The identification of the relaxation control mechanism and therapeutic restoration of a stringent screen may have considerable medical implications.

Adult↗
PubMed2003

Prediction of oral bioavailability by adaptive fuzzy partitioning.

An adaptive fuzzy partition (AFP) algorithm was applied on two bioavailability data sets subdivided into four ranges of activity. A large set of molecular descriptors was tested and the most relevant parameters were selected with help of a procedure based on genetic algorithm concepts and stepwise method. After building several AFP models on a training set, the best ones were able to predict correctly 75% of the validation set compounds. Furthermore, an improvement of about 15% in the validation results was got, on the same data set, as regard to other prediction methods. The importance to work with data sets including a large molecular diversity, and to use tools able to manage it, was also shown. The prediction power was increased up to 25% employing a data set with a better-optimised molecular diversity.

Administration, Oral↗
PubMedDate not supplied

Adaptive variation in environmental and genetic sex determination in a fish.

Two general mechanisms of sex determination have been identified among gonochoristic vertebrates: environmental sex determination where offspring become male or female in response to an environmental factor(s) during development (for example, some fishes and reptiles); and genetic sex determination where sex is determined by genotype at conception (as in birds and mammals). How do these sex-determining systems evolve? Direct evidence is virtually non-existent because the sex-determining systems of most species appear to have little genetic variation. Here we provide the first evidence of adaptive variation in environmental and genetic sex determination within a species. We show that in a fish with temperature-dependent sex determination, populations at different latitudes compensate for differences in thermal environment and seasonality by adjusting the response of sex ratio to temperature, and by altering the level of environmental as opposed to genetic control. The adjustments observed are precisely those predicted by adaptive sex ratio theory.

Adaptation, Physiological↗
PubMed2000

Risk-resistance adaptation model for caregivers and their children with sickle cell syndromes.

This investigation examined the risk-resistance adaptation model for children with sickle cell disease and their primary caregivers. Participants were 55 children, ranging in age from 5 to 16 years with a mean age of 9 years 2 months, diagnosed with sickle cell disease and their primary caregivers, recruited from a university medical center. Measures included adjustment (i.e. primary caregiver and child adjustment), risk factors (i.e. disease and disability, functional independence, and psychosocial stressors), resistance factors (i.e. intrapersonal health locus of control, social-ecological), and stress processing (coping). Primary caregivers' adjustment was associated with developmental coping, changeR2 = .08, and child adaptation was associated with an internal health locus of control, changeR2 = .22. An indirect effect of primary caregivers' coping on child adjustment was found through influence on primary caregivers' adjustment, changeR2 = .11. The findings support research among other chronically ill populations that suggests an association between coping and disease adjustment. The results were interpreted to support the use of theoretically driven models in predicting the adaptation of children with chronic illness and adjustment in their caregivers.

Adaptation, Psychological↗
PubMed2003

Work losses related to inflammatory bowel disease in Canada: results from a National Population Health Survey.

OBJECTIVE: Few studies have assessed the influence of inflammatory bowel disease (IBD) on work loss or estimated the costs related to work loss. Our analysis reports the employment effects related to IBD as based on the 1998 sample of the Canadian National Population Health Survey (NPHS). METHODS: Our predictive analysis adapts the theory of labor supply to a health context. Respondents between the ages of 20 and 64 who reported that they had been diagnosed by a health professional to have "a bowel disorder such as Crohn's disease or colitis" were distinguished from the other respondents. A logistic regression model was used to estimate the OR for labor force nonparticipation and variables predictive of it in the case of IBD. For those people in the labor force, the Cox proportional hazard model was used to determine whether having IBD and similar bowel disorders had an effect on the number of months of continuous employment. RESULTS: Of the IBD patients 28.9% reported labor force nonparticipation, which was a greater proportion than the non-IBD respondents (18.5% nonparticipation). The OR was 1.20 (95% CI = 1.19-1.21) for nonparticipation of IBD patients versus non-IBD patients controlling for potentially confounding factors. We estimated the excess nonparticipation attributable to IBD and similar bowel disorders in Canada to be 2.9%. Based on this, the indirect cost of nonparticipation attributable to IBD in 1998 was >$104.2 million Canadian dollars. According to the second regression using the Cox proportional hazard model, IBD and similar bowel disorders were not significantly related to the number of months worked until a break in employment was reported. Thus, there was no excess work loss among those who were employed that was associated with IBD. CONCLUSIONS: By using directly observed data in our analysis, this method of estimation can predict the overall burden of IBD and similar bowel disorders, controlling for the effect of other potentially influential characteristics.

Adult↗
PubMed1988

Relationships of oxygen uptake and oxygen delivery in respiratory failure not due to the adult respiratory distress syndrome.

Previous studies have suggested that oxygen uptake (VO2) may be dependent on oxygen delivery (QO2) at most levels of QO2 in patients with the adult respiratory distress syndrome (ARDS); however, the adequacy of substrate delivery in patients with non-ARDS respiratory failure is unclear. The purpose of the present study was to examine the relationship between VO2 and QO2 in a group of critically ill patients (n = 10) with non-ARDS respiratory failure (ie, cardiac pulmonary edema, chronic obstructive pulmonary disease [COPD], or pneumonia). For comparison, these relationships were also examined in a group of patients (n = 6) with ARDS. The data indicate that VO2 is dependent on QO2 in both patients with ARDS and non-ARDS respiratory failure. In contrast, regional venous oxygen tension differences varied considerably between the two groups of patients, indicating differences in local adaptations to critical reductions in QO2. Finally, over a similar range of QO2, oxygen extraction was greater in patients with ARDS compared to patients with non-ARDS respiratory failure (r = -0.67 and slope = -0.62 vs r = -0.45 and slope = -0.35; p less than 0.05). These data suggest that a linear relationship between VO2 and QO2 is not unique to patients with ARDS and may not predict regional adaptations to critical reductions in substrate availability.

Hemodynamics↗
PubMedDate not supplied

[Reliability of autoregulatory mechanisms of biosystems as affected by ionizing radiation].

Reliability of biosystems in processes of adaptation and homeostasis after whole-body irradiation of rats with different doses was determined in terms of the stochastic process theory developed for the autoregulatory systems with random parameters. Fluctuations in the rate of spontaneous chemiluminescence of blood serum and accumulation of lipid peroxidation products by erythrocyte membranes of rat blood were taken as the initial material. The analysis of fluctuations of peculiar parameters permitted to predict the adaptability of the system and to make timely corrections.

Animals↗
PubMed1985

On the optimality of coarse behavior rules.

Animal behavior can be characterized by the degree of responsiveness it has to variations in the environment. Some behavior rules lead to fine-tuned responses that carefully adjust to environmental cues, while other rules fail to discriminate as carefully, and lead to more inflexible responses. In this paper we seek to explain such inflexible behavior. We show that coarse behavior, behavior which appears to be rule-bound and inflexible, and which fails to adapt to predictable changes in the environment, is an optimal response to a particular type of uncertainty we call extended uncertainty. We show that the very variability and unpredictability that arises from extended uncertainty will lead to more rigid and possibly more predictable behavior. We relate coarse behavior to the failures to meet optimality conditions in animal behavior, most notably in foraging behavior, and also address the implications of extended uncertainty and coarse behavior rules for some results in experimental versus naturalistic approaches to ethology.

Adaptation, Physiological↗
PubMed2000

'Sloppy' sperm mixing and intraspecific variation in sperm precedence (P2) patterns.

Sperm precedence patterns are typically highly variable within (and between) species. Intraspecific variation in sperm precedence (measured as P2, the proportion of progeny fathered by the last male to mate' is frequently seen as a candidate for adaptive interpretation through either male effects (e.g. body size), female effects (e.g. cryptic female choice) or an interaction between the two. Here we show, using computer simulation, that if ejaculates divide into a number of 'packets' and packets from two males mix randomly, then a variety of patterns of sperm precedence may result. We term this process 'sloppy' mixing. If ejaculates break into a small number of packets, bimodal P2 distributions are predicted. As the number of packets is increased, then a complex series of changes through multimodal and flat to unimodal distributions results. Sloppy mixing can thus result in many of the observed P2 distributions. Sloppy mixing is unlikely to change the predictions of adaptive models of sperm competition.

Animals↗
PubMed2005

Two-hour post-dose cyclosporine levels in renal transplantation in Argentina: a cost-effective strategy for reducing acute rejection.

UNLABELLED: Monitoring of cyclosporine (microemulsion CsA) at 2 hours post-dose (C2), a measure of absorption and exposure, appears superior to trough (C0) monitoring for prediction of rejection risk. The purpose of this study was to determine whether C2 was cost-effective compared to C0 in Argentina. METHODS: A predictive decision model was adapted to Argentina to predict costs associated with C0 and C2 measurements in the first year after transplantation. Patients were treated with microemulsion CsA, steroids and azathioprine or MMF. Parameter estimates for the C0 strategy were based on event rates observed in published clinical trials. The model was adapted to Argentinean health system through local protocols and expert opinions; costs were valued in Argentinean pesos and converted to US dollars (1 USD = 2.85 ARS). RESULTS: Incidence of acute rejection was predicted to be 25.0% at 1-year among patients monitored by C0 and 18.0% by C2. Graft survival was predicted to be 1.4% lower in the C0 group. No important differences were identified in co-morbidity, C0 and C2 monitoring costs, and in ambulatory-based adverse events between C0 and C2 cohorts. The model predicted an average cost per patient of $16,269 for C0 and $16,343 for C2 testing (year 1). Sensitivity analyses indicated that the average daily dose of microemulsion CsA was the most important parameter leading to the incremental cost per patient. CONCLUSIONS: C2 is expected to provide a potentially important reduction in the risk of acute rejection without increasing the estimated cost of care in the first year post-transplant.

Acute Disease↗
PubMed2003

Error monitoring using external feedback: specific roles of the habenular complex, the reward system, and the cingulate motor area revealed by functional magnetic resonance imaging.

The dopaminergic system has been shown to be involved in the processing of rewarding stimuli, specifically of errors in reward prediction, in animal studies as well as in recent neuroimaging studies in humans. Furthermore, a specific role of dopamine in the human homolog of the rostral cingulate motor area (rCMA) was proposed in a recent model of error detection. Negative feedback as well as self-detected errors elicit a negative event-related brain potential probably generated in the rCMA. We performed two experiments using functional magnetic resonance imaging to investigate the brain activity related to negative and positive feedback in a dynamically adaptive motion prediction task. Whereas positive feedback raised hemodynamic activity in the ventral striatum (nucleus accumbens), negative feedback activated the rCMA, the inferior anterior insula, and the epithalamus (habenular complex). These data demonstrate the role of the habenular complex in the control of the human reward system, a function previously hypothesized on the basis of animal research. The rCMA reacted only to errors with negative feedback but not to errors without feedback, which ruled out an influence of response conflict or uncertainty on its role in error detection by external signals.

Adult↗
PubMed2005

Structural prediction of peptides bound to MHC class I.

An ab initio structure prediction approach adapted to the peptide-major histocompatibility complex (MHC) class I system is presented. Based on structure comparisons of a large set of peptide-MHC class I complexes, a molecular dynamics protocol is proposed using simulated annealing (SA) cycles to sample the conformational space of the peptide in its fixed MHC environment. A set of 14 peptide-human leukocyte antigen (HLA) A0201 and 27 peptide-non-HLA A0201 complexes for which X-ray structures are available is used to test the accuracy of the prediction method. For each complex, 1000 peptide conformers are obtained from the SA sampling. A graph theory clustering algorithm based on heavy atom root-mean-square deviation (RMSD) values is applied to the sampled conformers. The clusters are ranked using cluster size, mean effective or conformational free energies, with solvation free energies computed using Generalized Born MV 2 (GB-MV2) and Poisson-Boltzmann (PB) continuum models. The final conformation is chosen as the center of the best-ranked cluster. With conformational free energies, the overall prediction success is 83% using a 1.00 Angstroms crystal RMSD criterion for main-chain atoms, and 76% using a 1.50 Angstroms RMSD criterion for heavy atoms. The prediction success is even higher for the set of 14 peptide-HLA A0201 complexes: 100% of the peptides have main-chain RMSD values < or =1.00 Angstroms and 93% of the peptides have heavy atom RMSD values < or =1.50 Angstroms. This structure prediction method can be applied to complexes of natural or modified antigenic peptides in their MHC environment with the aim to perform rational structure-based optimizations of tumor vaccines.

Algorithms↗
PubMed1988

[Subjective verbal methods in preoperative measurement of anxiety].

The role of preoperative anxiety in perioperative adaptation is viewed in two different ways. Janis suggested that anxiety is a drive that evokes the cognitive work of worrying. Leventhal stresses the importance of coping behavior for adaptation, while anxiety may or may not accompany this coping process. Both theories have empirical support. The aim of this study was to determine whether both theories could show empirical support because the scientists chose different methods: Janis used interviews, Leventhal and Lazarus anxiety scales. The study analyzed the pre- and postoperative emotional reactions of surgical patients with three different methods of anxiety measurement: an anxiety scale, a fear thermometer, and a psychoanalytic interview (Gottschalk-Gleser content analysis method). The different methods were compared and related to the adaptation behavior (Table 3). The data showed a clear interaction between the selected methods and respective theories about the effects of preoperative anxiety on intra- and postoperative adaptation. The anxiety scales showed no correlation with adaptation behavior (blood pressure and heart rate during surgery; postoperative pain medication) and were not related to the anxiety scores obtained from the interview (content analysis). On the other hand, the interview anxiety measurements showed a clear relationship between separation anxiety (and also shame anxiety), physiological excitement during surgery (increase in heart rate), and postoperative medication (increased analgesics and tranquilizers). The patients who worried about the risks of surgery (Verletzungsangst, see Fig. 3) had very good perioperative adjustment, so that the quality of anxiety measured in the interview was very important for the prediction of adaptation.

Adaptation, Psychological↗
PubMed1990

Application of the theory of adaptive polymorphism to the ecology and epidemiology of pathogenic yeasts.

The theory of adaptive polymorphism predicts that species occupying broad ecological niches will be phenotypically and genotypically more varied than those occupying narrow niches. It is suggested that this theory has direct relevance to the epidemiology of microbial pathogens in that environmental pathogens inhabit a broader niche and should be expected to exhibit greater variation than pathogens that are obligate commensals. This proved to be the case when one obligate commensal, the pathogenic yeast Candida albicans, was compared with other Candida spp. and an environmental pathogen, Cryptococcus neoformans. Further evidence of this relationship is derived from the literature. This observation adds further support to the theory of adaptive polymorphism, although the mechanisms of maintenance of polymorphism is asexually reproducing populations must be different from those in sexually reproducing populations. This observation may give important clues to the epidemiology of those infections for which it is not already known.

Adaptation, Biological↗