The successful treatment of a 40-year old passive homosexual based on an adaptational view of sexual behavior.
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Homosexuality↗
SEARCH · PubMed Health
Results for “passive adaptation”
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[Effects of general anesthesia for cesarean section on infants].
OBJECTIVE: To determine the safety of general anesthesia during cesarean section for neonates. METHODS: Singleton pregnant women for whom elective cesarean sections were planned after 37 gestation weeks were allocated to general anesthesia or epidural anesthesia. After preoxygenation, general anesthesia was induced with fentanyl (2.0 microg/kg), propofol (1.5 mg/kg) and vencuronium (0.08 mg/kg) followed by tracheal intubation. Oxygen-nitrous oxides (50%) was inhaled before delivery. Epidural anesthesia was performed at L(1 - 2) or L(2 - 3) on the left lateral decubitus position with 1.73% lidocaine carbonate (including 1:200 000 adrenaline). We studied arterial samples withdrawn from the infants 30 min after birth for the pH, PaO(2), PaCO(2), SPO(2) and Hct. Neonatal behavioral neurological assessments (NBNA) 3 - 5 days after birth were recorded. RESULTS: (1) The pH, PaO(2), PaCO(2), SPO(2) and Hct in the general anesthesia group were 7.34 +/- 0.08, (40 +/- 11) mm Hg, (73 +/- 17) mm Hg, (96.8 +/- 1.0)%, and (53 +/- 5)%, while in the epidural anesthesia group were 7.35 +/- 0.05, (41 +/- 8) mm Hg, (71 +/- 17) mm Hg, (96.6 +/- 1.0)%, and (54 +/- 6)%. (2) NBNA scores: In the general anesthesia group, neonatal adaptive capacity, passive tone, active tone, primary reflexes and general status were 12.6 +/- 0.7, 7.2 +/- 0.7, 7.4 +/- 0.6, 5.6 +/- 0.8, and 5.9 +/- 0.3 respectively. While in the epidural anesthesia group they were 13.4 +/- 0.8, 7.3 +/- 0.5, 7.3 +/- 0.8, 5.6 +/- 0.6, and 5.9 +/- 0.3 respectively. No significant difference was seen (P > 0.05) between the general anesthesia group and the epidural anesthesia group in NBNA scores, mean pH, PaO(2), PaCO(2), SPO(2) and Hct of newborn infants. CONCLUSION: It study suggests that general anesthesia for the elective cesarean section does not influence significantly the outcome of the newborn infants.
Adult↗
Learning experiences of medical students by different instructional methods.
We made a prospective study to determine students' response and perception of the various instructional methods during their pediatric rotation. We found that even those students who were used to passive learning adapted to the more self active learning and became more interested in this method.
Curriculum↗
Core passive and facultative mTOR-mediated mechanisms coordinate mammalian protein synthesis and decay.
The maintenance of cellular homeostasis requires tight regulation of proteome concentration and composition. To achieve this, protein production and elimination must be robustly coordinated. However, the mechanistic basis of this coordination remains unclear. Here, we address this question using quantitative live-cell imaging, computational modeling, transcriptomics, and proteomics approaches. We found that protein decay rates systematically adapt to global alterations of protein synthesis rates. This adaptation is driven by a core passive mechanism supplemented by facultative changes in mechanistic/mammalian target of rapamycin (mTOR) signaling. Passive adaptation hinges on changes in the production rate of the machinery governing protein decay and allows for partial maintenance of the cellular proteome. Sustained changes in mTOR signaling provide an additional layer of adaptation unique to naive pluripotent stem cells, allowing for near-perfect maintenance of proteome composition. Our work unravels the mechanisms protecting the integrity of mammalian proteomes upon variations in protein synthesis rates. A record of this paper's transparent peer review process is included in the supplemental information.
TOR Serine-Threonine Kinases↗
The effects of the duration of adaptation to laboratory conditions on the formation of a passive avoidance reflex in rats.
The level of adaptation of rats to their new living conditions was studied during formation of a passive avoidance habit using a single combination. A short acclimation period (3 days) had positive influences on the ability of rats to retain a memory trace. There was a negative correlation between step-through latency and measures of anxiety behavior in the elevated cross maze. A change in the adaptation period to nine days decreased the state of anxiety and the level of performance of the conditioned response. There were no correlations between these measures. The modulating role of the level of adaptation to living conditions, associated with different levels of anxiety, in a passive one-session avoidance learning model was assessed.
Adaptation, Psychological↗
[Adrenal cortical function in elaborating a passive avoidance conditioned reflex in rats adapted to experimental conditions].
Fluorometry was used to determine the content of 11-hydroxycorticosteroids (11-HCS) in the blood plasma of 2-month-old male rats in the course of passive avoidance learning by means of single electrocutaneous irritation (ECI) of the limbs. Pre-exposure of the animals for 7 days to experimental environment (over 3 min daily) led to a distinct reduction of the basal content of 11-HCS which returned to the initial level after adaptation discontinuance. One day after ECI the content of 11-HCS in rats which learned passive avoidance, was appreciably lower as compared to that in the animals which failed to learn the behavioral task. Five days after ECI the differences in the content of the corticosteroids in the animals of the two groups were little pronounced. It appears that while using passive avoidance as a long-term memory model, account should be taken of both the behavioral and emotional responses.
11-Hydroxycorticosteroids↗
Effects of an eight-week stretching program on the passive-elastic properties and function of the calf muscles of older women.
BACKGROUND: Calf muscle stretching programs are used to increase dorsiflexion range of motion at the ankle, yet the effects of the stretching programs on the passive properties of aged calf muscles and on standing and ambulatory function have not been studied. This initial study examined the effects of an eight-week stretching program on the passive-elastic properties of the calf muscles of older women and on selected functional activities. METHODS: Nineteen women aged 65-89 years with limited dorsiflexion range of motion first completed a timed agility course, a timed 10-m walk and a standing functional reach test. A dynamometer then moved the right ankle from plantarflexion to maximal dorsiflexion and back to plantarflexion at 5 deg s(-1) to measure calf muscle passive properties. The women were randomly assigned to a group that stretched three-times a week for eight-weeks (n=10) or to a control group (n=9) that did not. The tests were repeated after the stretching program. FINDINGS: The stretching group showed increased maximal dorsiflexion range of motion, passive resistive forces (Newtons [N]), and the absorbed and retained passive-elastic energy (deg N) (P<0.05). They also had decreased times for the agility course and the 10-m walk (P<0.05). The functional reach test did not change for either group. INTERPRETATION: The eight-week stretching program most likely increased the maximal length, length extensibility and passive resistive forces of the calf muscles. Adaptations of other ankle and leg structures also may have contributed. The passive adaptations were associated with enhanced performances of ambulatory functional activities.
Aged↗
Adaptation-induced plasticity of orientation tuning in adult visual cortex.
A key emergent property of the primary visual cortex (V1) is the orientation selectivity of its neurons. The extent to which adult visual cortical neurons can exhibit changes in orientation selectivity is unknown. Here we use single-unit recording and intrinsic signal imaging in V1 of adult cats to demonstrate systematic repulsive shifts in orientation preference following short-term exposure (adaptation) to one stimulus orientation. In contrast to the common view of adaptation as a passive process by which responses around the adapting orientation are reduced, we show that changes in orientation tuning also occur due to response increases at orientations away from the adapting stimulus. Adaptation-induced orientation plasticity is thus an active time-dependent process that involves network interactions and includes both response depression and enhancement.
Adaptation, Physiological↗
Simulating unilateral neglect in normals using prism adaptation: implications for theory.
Rightward deviation on line bisection is considered one of the most classic clinical signs of unilateral visual neglect--a cognitive disorder of spatial processing that commonly follows right brain damage. Recently, short-term adaptation to wedge prisms has been shown to significantly reduce neglect on this and other conventional diagnostic tasks. Our previous study has shown that visuomotor adaptation in normals produces a similar pattern of directional bias on a line bisection task. Based on the good working knowledge of how neglect patients perform on different versions of the standard diagnostic task, we showed here that using leftward-deviating prisms in normals, it is possible to produce: (1) a reliable bias on line bisection, (2) a rightward specific deviation, (3) a modulation of rightward deviation, which depends on the relative spatial location of the target lines and (4) a line length effect. A final experiment confirmed that these after-effects are specific to prism adaptation rather than passive prism exposure. Collectively, these findings confirm that adaptation to left-deviating prisms in normals produces a reliable right-sided bias and as shown by a previous visuospatial judgement task, these findings cannot be adequately explained by the symmetric sensori-motor effects of prism adaptation. Taken together with the improvement of spatial neglect shown by right-deviating prisms only, the present study suggests that low level sensori-motor adaptations play a greater role in right hemisphere organisation for spatial cognition than previously thought.
Adaptation, Physiological↗
Stretch reflex adaptation in elbow flexors during repeated passive movements in unilateral brain-injured patients.
OBJECTIVE: To evaluate the effects of repeated, externally imposed, flexion-extension movements of the elbow on the resulting stretch reflex response in hemiparetic spastic brain-injured patients. These effects were compared within a recording session and across sessions for the same subject to determine the impact of movement history on the quantification of spastic hypertonia using the stretch reflex response. DESIGN: Twenty to 30 sequential, constant velocity flexion-extension movements were applied to the impaired elbow of our cohort, with a 10-second hold interposed between flexion and extension. Movements were applied regularly at 1-minute intervals. Changes in stretch reflex responses were monitored during the applied movements. PARTICIPANTS: We examined a convenience sample of seven hemiparetic brain-injured subjects between the ages of 26 and 60 yrs, with moderate-to-severe spastic hypertonia of elbow muscles (Ashworth score 2-4/4). Subjects participated in 2 to 9 sessions. MEASURES: Elbow torque, position, velocity, and electromyograms of the biceps, brachioradialis, and triceps muscles were recorded for each flexion and extension movement. Stretch reflex torque was calculated by subtracting passive torque from total elbow torque, recorded over large amplitude movements. A linear regression analysis quantified both the initial torque response of the stretch reflex and the ensuing adaptation of the stretch reflex during sequential movements. Intersession variability was characterized both for spastic hypertonia measures and for stretch reflex adaptation. RESULTS: Repeated, externally imposed, sequential flexion-extension movements of the elbow decreased the elbow flexor stretch reflex in six of seven subjects. The mean reduction in reflex torque after 30 movements was 50% of the initial torque values (p = .001, t test vs. 0% change). Intersession stretch reflex responses for each subject were found to vary greatly (SDs of reflex torque ranged from 0.1 to 4.0 Nm), and there were also significant variations in the degree of adaptation between subjects. CONCLUSIONS: Stretch reflex adaptation must be taken into consideration when spastic hypertonia is quantified using repeated joint motion, as is often the case. The magnitude of intersession variation in spastic hypertonia measures suggests that ideally, such measurements should be made across multiple sessions before conclusions are made regarding the efficacy of spastic hypertonia interventions. This study provides quantitative evidence that repeated joint movements may have a significant short-term beneficial effect on spastic hypertonia.
Adaptation, Physiological↗
Effects of passive enhancement on graft and host. Graft adaptation by alloantibody as the mechanism of prolonged skin allograft survival.
The cellular response to passively enhanced allogeneic skin grafts in mice was investigated using alloantiserum raised in hyperimmunized (C57BL/6 X A/J)F1 (B6AF1) against B10.D2oSn (B10.D2) mice. B6AF1 mice given B10.D2 skin grafts and passively enhanced with B6AF1 anti-B10.D2 alloantiserum (anti-31) showed delayed development of the ability to generate high levels of specific cytotoxicity in vitro. This delayed responsiveness was not transferable in vivo to freshly skin grafted mice, nor could cell-mediated suppression of development of in vitro responses be demonstrated in mixing experiments. These results suggested that alloantiserum acted on the graft. When skin grafts from passively enhanced animals were transferred to naive recipients prolonged graft survival was seen. Our results suggest that the mechanism of prolonged graft survival of the passively enhanced murine skin graft was through alteration of inherent graft immunogenicity, rather than a direct effect on the host.
Animals↗
Adaptation to long term stretch in the passive discharge of muscle spindles.
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Action Potentials↗
[The role of corticotropin-releasing hormone in alteration of adaptive behavior of the active and passive rats after inescapable stress].
Effects of corticotropin-releasing hormone (CRH) on the formation of post-stress psychopathology were studied using of two genetic strains KHA (Koltushi high Avoidance) and KLA (Koltushi low Avoidance) selected on high or low acquisition of active avoidance, respectively. These strains are characterized by higher (KHA) and lower (KLA) behavioral activity in open field and adopted, respectively, active and passive strategies in stressful conditions. A widely used experimental paradigm of learned helplessness where behavioral depression was produced by inescapable uncontrollable footshock has been applied in our study. KHA rats demonstrated psychopathology already 1st day following exsposure to the stress faktor, and the depression progressed by the 5th and 10th post-stress days. Intranasal application of CRH facilitated the development of depression in active rats. In KLA rats, which originally displayed low exploratory activity associated with high anxiety, the inescapable stress at first enhanced the exploratory behavior but 10 days later these rats displayed a progressive decline of exploration and locomotion. Initially, the application of CRH also enhanced the exploratory behavior in these rats, but to 10th post-stress day promoted development of depressive state. The results suggest that CRH in different ways affects the formation of depressive state in rats with different strategies of adaptive behavior.
Adaptation, Psychological↗
Fibre size and type adaptations to spinal isolation and cyclical passive stretch in cat hindlimb.
Impulse activity is known to have a strong influence in determining the characteristics that distinguish skeletal muscle fibres into types. The control of muscle proteins by the neural systems that innervate the muscles, however, is not complete (Edgerton et al. 1985, 1990). The purpose of the present study, therefore, was to determine the effects of inactivity for 6 months on the size and fibre type composition of selected cat hindlimb muscles. Inactivity was produced by isolating the lumbar region of the spinal cord, i.e. transecting the cord at T12-T13 and again at L7-.S1 and then performing a bilateral dorsal rhizotomy between the transection sites (SI). In each SI cat, one hindlimb was passively manipulated for 30 min per day through a range of motion at the ankle mimicking a step cycle. SI resulted in an atrophic response in most muscles, with predominantly slow extensors showing the largest effect. In general, the predominant fibre type, which also had the largest mean size, in each muscle atrophied the most. The mean fibre size of all fibre types were similar after SI, suggesting that there may be a minimal size for inactive intact fibres. In comparison with control animals, all muscles in the SI cats had a higher proportion of fast fibres. Further, the relative contribution of the slow fibres to the total cross-sectional area of the muscle was decreased following SI. Some slow fibres in each muscle, however, were resistant to change. These data demonstrate the extent to which size and myosin type of mammalian muscle fibres are independent of activation characteristics.
Adaptation, Physiological↗
Passive muscle stiffness may be influenced by active contractility of intramuscular connective tissue.
The article introduces the hypothesis that intramuscular connective tissue, in particular the fascial layer known as the perimysium, may be capable of active contraction and consequently influence passive muscle stiffness, especially in tonic muscles. Passive muscle stiffness is also referred to as passive elasticity, passive muscular compliance, passive extensibility, resting tension, or passive muscle tone. Evidence for the hypothesis is based on five indications: (1) tonic muscles contain more perimysium and are therefore stiffer than phasic muscles; (2) the specific collagen arrangement of the perimysium is designed to fit a load-bearing function; (3) morphological considerations as well as histological observations in our laboratory suggest that the perimysium is characterized by a high density of myofibroblasts, a class of fibroblasts with smooth muscle-like contractile kinetics; (4) in vitro contraction tests with fascia have demonstrated that fascia, due to the presence of myofibroblasts, is able to actively contract, and that the resulting contraction forces may be strong enough to influence musculoskeletal dynamics; (5) the pronounced increase of the perimysium in muscle immobilization and in the surgical treatment of distraction osteogenesis indicates that perimysial stiffness adapts to mechanical stimulation and hence influences passive muscle stiffness. In conclusion, the perimysium seems capable of response to mechanostimulation with a myofibroblast facilitated active tissue contraction, thereby adapting passive muscle stiffness to increased tensional demands, especially in tonic musculature. If verified, this new concept may lead to novel pharmaceutical or mechanical approaches to complement existing treatments of pathologies which are accompanied by an increase or decrease of passive muscle stiffness (e.g., muscle fibroses such as torticollis, peri-partum pelvic pain due to pelvic instability, and many others). Methods for testing this new concept are suggested, including histological examinations and specific in vitro contraction tests.
Elasticity↗
Plasticity to light cues and resources in Arabidopsis thaliana: testing for adaptive value and costs.
Plants shaded by neighbors or overhead foliage experience both a reduction in the ratio of red to far red light (R:FR), a specific cue perceived by phytochrome, and reduced photosynthetically active radiation (PAR), an essential resource. We tested the adaptive value of plasticity to crowding and to the cue and resource components of foliage shade in the annual plant Arabidopsis thaliana by exposing 36 inbred families from four natural populations to four experimental treatments: (1) high density, full sun; (2) low density, full sun; (3) low density, neutral shade; and (4) low density, low R:FR-simulated foliage shade. Genotypic selection analysis within each treatment revealed strong environmental differences in selection on plastic life-history traits. We used specific contrasts to measure plasticity to density and foliage shade, to partition responses to foliage shade into phytochrome-mediated responses to the R:FR cue and responses to PAR, and to test whether plasticity was adaptive (i.e., in the same direction as selection in each environment). Contrary to expectation, we found no evidence for adaptive plasticity to density. However, we observed both adaptive and maladaptive responses to foliage shade. In general, phytochrome-mediated plasticity to the R:FR cue of foliage shade was adaptive and counteracted maladaptive growth responses to reduced PAR. These results support the prediction that active developmental responses to environmental cues are more likely to be adaptive than are passive resource-mediated responses. Multiple regression analysis detected a few costs of adaptive plasticity and adaptive homeostasis, but such costs were infrequent and their expression depended on the environment. Thus, costs of plasticity may occasionally constrain the evolution of adaptive responses to foliage shade in Arabidopsis, but this constraint may differ among environments and is far from ubiquitous.
Adaptation, Physiological↗
Adaptation to visual displacement with active and passive limb movements: effect of movement frequency and predictability of movement.
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Adaptation, Psychological↗
Constraints on the evolution of adaptive phenotypic plasticity in plants.
The high potential fitness benefit of phenotypic plasticity tempts us to expect phenotypic plasticity as a frequent adaptation to environmental heterogeneity. Examples of proven adaptive plasticity in plants, however, are scarce and most plastic responses actually may be 'passive' rather than adaptive. This suggests that frequently requirements for the evolution of adaptive plasticity are not met or that such evolution is impeded by constraints. Here we outline requirements and potential constraints for the evolution of adaptive phenotypic plasticity, identify open questions, and propose new research approaches. Important open questions concern the genetic background of plasticity, genetic variation in plasticity, selection for plasticity in natural habitats, and the nature and occurrence of costs and limits of plasticity. Especially promising tools to address these questions are selection gradient analysis, meta-analysis of studies on genotype-by-environment interactions, QTL analysis, cDNA-microarray scanning and quantitative PCR to quantify gene expression, and two-dimensional gel electrophoresis to quantify protein expression. Studying plasticity along the pathway from gene expression to the phenotype and its relationship with fitness will help us to better understand why adaptive plasticity is not more universal, and to more realistically predict the evolution of plastic responses to environmental change.
Adaptation, Physiological↗