PubMed Health⌕ Search

SEARCH · PubMed Health

Results for “passive adaptation”

Explore indexed PubMed citations for clinical trials, systematic reviews and public health research. Read source abstracts and follow each citation to its original PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 127 records · Page 7Linked to original sources
PubMed2002

Passive stiffness changes in soleus muscles from desmin knockout mice are not due to titin modifications.

Passive stiffness was found to be increased in mouse soleus muscles lacking desmin. Because titin is considered to be the major source of muscle elasticity, the stiffening might be explainable by titin adaptation. To test this, passive mechanical properties of single skinned fibres of soleus muscles from desmin knockout and control mice were analysed by using various extension tests. Titin expression was studied by SDS-gel electrophoresis. Absence of desmin did not modify either electrophoretic mobility of the titin band (3700 kDa) or optical density-unit ratios between bands for titin and nebulin (congruent with 0.3) and bands for titin and myosin heavy chain (congruent with 0.08). Elastic properties of fibres were not altered in the absence of desmin since passive tensions were similar under quasi-static (56-66 kN m(-2)) and dynamic (100-118 kN m(-2)) conditions whatever the kind of fibre. Thus, titin is unlikely to be responsible for the large increase in passive stiffness observed in whole soleus muscles when desmin is lacking.

Animals↗
PubMed2004

K+ channels and their modulation by 5-HT in Drosophila photoreceptors: a modelling study.

In order to clarify the role of inactivating and noninactivating K+ conductances in nonspiking neurons, we developed an isopotential model of the Drosophila photoreceptor membrane based on Hodgkin-Huxley-type equations. The model includes voltage dependent potassium conductances, the shaker (gKA) and the delayed rectifier (gKs). The model parameters were derived from published results by Hardie and coworkers and nearly identical model was used also in our previous work (J. E. Niven, M. Vähäsöyrinki, M. Kauranen, R. C. Hardie, M. Juusola, and M. Weckström. The Contribution of shaker K+ channels to the information capacity of Drosophila photoreceptors. Nature. 421:630-634, 2003). The model explains how the two types of channels function together to define the voltage dependent properties of the photoreceptor membrane. Additionally the model enables us to run simulations of conditions which are difficult to achieve in patch clamp, like prolonged membrane depolarizations by light adaptation. Effects of the activation of the delayed rectifier type conductance were found to be in accordance with published experimental work but the inactivation of the shaker channels, in addition to its importance in the determination of the resting potential, produced voltage amplification over equivalent passive membrane under dark adapted conditions. This phenomenon was not present in light adapted conditions. The modulation of the voltage dependence of the conductances as reported by serotonin (5-HT) caused the shaker to act essentially like the delayed rectifier conductance.

Animals↗
PubMed2002

The unoperated hand: the role of passive forces in hand function after tetraplegia.

Passive forces play a large role in hand function after tetraplegia. Most individuals with tetraplegia choose not to undergo surgical reconstruction of hand function and, therefore, depend on the passive properties of their musculoskeletal system to perform functional tasks. Knowledge of the levels of force needed to perform many of these tasks is lacking. Understanding the mechanics of producing passive force is important for designing adaptive tools and other devices for tetraplegic individuals. Knowledge of the passive properties of the upper extremity is important in forming treatment strategies. The passive forces produced for change to the tenodesis grasp are small but useful to the individual. Since these forces arise from basic anatomy and muscle function, they are important even after surgical restoration of hand function. Compensatory strategies for the unoperated hand probably play a role in the operated hand. The approach to surgical restoration of grasp must consider how passive forces contribute to functional outcome.

Adaptation, Physiological↗
PubMed1991

[The effect of long-term administration of metipranolol on passive diastolic properties of the hypertrophic ventricle].

In the course of adaptation of the rabbit heart to volume load passive diastolic properties of the hypertrophic ventricle and myocardium were changing significantly. On day 30 following perforation of the aortic valve stiffness of the ventricle was reduced, yet normalized ventricular stiffness and myocardial stiffness were increased. These changes were prevented by beta adrenergic blockade during development of adaptation of the heart to volume load. Although ventricular stiffness was reduced, normalized ventricular stiffness and myocardial stiffness remained at the level of control values. The demonstrated effect of beta adrenergic blockade on passive diastolic properties of the ventricle and myocardium may be of value in preventing heart failure due to chronic hemodynamic load. (Tab.3,Ref.15.).

Animals↗
PubMedDate not supplied

Dopaminergic mechanisms of neostriatum in the regulation of adaptive behavior by corticoliberin.

A conditioned active avoidance response was developed in rats with high (KHA) and low (KLA) rates of learning and the effects of injection of corticoliberin into the dorsal striatum on orientational-investigative and avoidance behavior were studied in normal animals and after depletion of striatal dopamine by preliminary injection of 6-hydroxydopamine. These studies showed that corticoliberin, like 6-hydroxydopamine, produced similar trends in the animals' behavior. Their effects were mediated by opposite mechanisms in animals with initial active and passive learning strategies for adaptive behavior. The role of dopaminergic structures of the striatum in mediating the behavioral effects of corticoliberin is discussed.

Adaptation, Psychological↗
PubMedDate not supplied

[The effect of long-term adaptation to hypoxia on the open-field behavioral reactions in rats with different types of behavior].

We studied the influence of long-term (30 days) adaptation to hypobaric hypoxia (daily lifting to 5000 m for 5 h) on behaviour of rats with different typological characteristics and levels of resistance to hypoxia. Correlation was ascertained between the resistance of rats to oxygen deficiency and the open field locomotor activity. Adaptation was shown to induce the state of increased anxiety in animals of all the groups under study. In rats with the low resistance to hypoxia adaptation led to increase of exploratory activity. In rats with high initial resistance hypoxic influences caused an increased extinction of orienting reaction at repeated testing in the open field as well as motor excitation increase. In animals with active and medial types of behaviour hypoxic influences increased exploratory activity. In animals with the medial behavioural type increased exploratory activity was changed later by general motor excitation. In rats with the passive type of behaviour adaptation resulted in decrease of the number of rearings testifying to suppression of exploratory reactions, and in the phase changes of locomotor activity.

Acute Disease↗
PubMed1988

Time course of Na,K transport and other metabolic responses to thyroid hormone in clone 9 cells.

To elucidate the relationship between the stimulation of Na+ and K+ fluxes by thyroid hormone and the induction of the Na,K-ATPase, we performed a detailed comparison of the time courses of these hormonal effects in a rat liver cell line, clone 9. Stimulations of passive K+ efflux, passive Na+ influx, and ouabain-inhibitable K+ uptake were all evident within 6-12 h of exposure of cells to T3 (10(-7) M). The time course of the induction of Na,K-ATPase activity closely paralleled that of the increase in the rate of Na+ and K+ fluxes. The maximal stimulatory effects of T3 on ouabain-inhibitable K+ uptake and Na,K-ATPase activity at 72 h were +49% and +36%, respectively. Intracellular Na+ and K+ contents were virtually unchanged during these increases in ion fluxes and Na,K-ATPase activity, suggesting an efficient homeostatic adaptation to the augmented passive "leak" of Na+ and K+ down their transmembrane concentration gradients. T3 treatment for 72 h was also shown to stimulate both lactate production (+62%) and [3H]2-deoxyglucose uptake (+82%) in these cells. The onset of these effects appeared to precede that of the stimulation of Na+ and K+ fluxes, being detectable at 4 h. Neither these latter effects of T3 nor the stimulation of ouabain-inhibitable K+ uptake could be demonstrated when RNA or protein synthesis was inhibited by actinomycin D or cycloheximide, respectively. It is concluded that in clone 9 cells thyroid hormone causes increases in passive Na+ influx, passive K+ efflux, active Na,K transport, and Na,K-ATPase activity whose time courses are closely parallel.

Animals↗
PubMed2000

Coping strategies in patients with acquired brain injury: relationships between coping, apathy, depression and lesion location.

Coping strategies in individuals suffering severe traumatic brain injury (TBI), cerebrovascular accidents (CVA), or hypoxic brain injury (HBI) were investigated in relation to apathy, depression, and lesion location. Seventy patients (27 with TBI, 30 with CVA, and 13 with HBI) filled in a coping questionnaire (COPE) and were evaluated with respect to apathy and depression. A comparison sample of 71 students also filled in COPE. Patients coping strategies were similar to the comparison group, but patients tended to display less differentiated coping styles. A factor analysis indicated two dimensions of coping in the patient sample; approach oriented and avoidance oriented coping. Approach and avoidance coping sum scores, based on subscales from the two factors, were positively correlated in the patient sample, but not in the comparison group. Lack of active approach oriented coping was associated with apathy, whereas avoidant coping was associated with depression. Coping styles were not related to lesion location. Apathy was related to subcortical and right hemisphere lesions. In bivariate analyses, depression was unrelated to lesion location, but, in a MANCOVA, avoidant coping, apathy and lesion location (left hemisphere lesions) contributed to the variance in positive depressive symptoms. The consistent relationships between coping strategies and neuropsychiatric symptoms were interpreted as two dimensions of adaptational behaviour: an active vs. passive dimension and a depression--distress-avoidance dimension.

Adaptation, Psychological↗
PubMed2004

Decay of prism aftereffects under passive and active conditions.

In prism adaptation, subjects adapt to new visuospatial coordinates imposed by wedge prisms that laterally displace the visual field. During this process, subjects develop and store new visuomotor coordinates in order to compensate for the displacement of visual stimuli. After the prisms are removed, subjects show an aftereffect in the opposite direction of the original perturbation. The aftereffect is a manifestation of the recently stored information. In the present article, we were interested in studying the properties of the aftereffect. Specifically, we investigated the fate of the aftereffect under active conditions with motor reafferences but without visual input, and during passive conditions without visual or motor reafferences. The results in the motor active condition show that motor reafference (proprioceptive or corollary discharge information) led to a faster, but incomplete, aftereffect decay. The results in the passive condition show a bimodal aftereffect behavior, with a fast decay within the initial minutes, followed by a sustained aftereffect up to 20 min later. These data suggests that two different memory processes may contribute to the aftereffect, one showing a fast decay mainly within 1 min, and another that shows a stable endurance for more than 20 min.

Adaptation, Physiological↗
PubMed2005

Presence of a novel small RNA-containing virus in a laboratory culture of the endoparasitic wasp Venturia canescens (Hymenoptera: Ichneumonidae).

Parasitoid wasps use a variety of mechanisms to alter their host's physiology to the benefit of the developing endoparasite inside the host larva. Association of certain wasps with viruses and virus-like particles (VLPs) that contribute to their success in parasitism is one of the fascinating evolutionary adaptations conferring active or passive protection for the endoparasite from the host immune system. Venturia canescens has been shown to produce VLPs that provide protection for the developing parasitoid egg inside the host, Ephestia kuehniella. Here, we report on the presence of a novel small RNA-containing virus from V. canescens, designated as VcSRV, occurring in the ovaries of the wasp. The virus particles are found together with VcVLPs in the lumen of the calyx region of the ovaries and are injected together with the egg and VcVLPs into E. kuehniella larvae where they enter hemocytes. Alignment of the RNA-dependent RNA polymerase gene of VcSRV indicates that the virus most likely belongs to the recently described genus Iflavirus.

Amino Acid Sequence↗
PubMed2000

[Opinions and expectations of primary care professionals concerning team work].

OBJECTIVE: To find the views and expectations of professionals working at primary care centres on team-work. DESIGN: Qualitative study. Focus group. SETTING: The study was conducted during May 1997 at the following primary care centres: Terrassa North, Sant Llatzer (Terrassa) and Antón de Borja (Rubí). These PCCs depend on the Department of Health and Social Security and are managed by the Terrassa Health Consortium. PARTICIPANTS: 38 primary care professionals, distributed in 5 independent groups of 8 doctors, 9 nurses, 3 social workers, 9 clerical staff and 9 auxiliaries. MEASUREMENTS AND RESULTS: Qualitative methodology and focal group technique were used. Contents of session transcriptions were analysed and the information classified according to themes. Views on the definition of team-work, basic aspects of its proper functioning, restrictions met by professionals at present and suggestions to overcome these restrictions were all identified. CONCLUSIONS: The setting of objectives, the clear and structured definition of the functions of each professional group, the participation of all the team components in decision-taking, communication, and positive enabling approaches to team-work were all specified as basic features of the team's proper functioning. Ill-defined functions, few meetings, heterogeneity within the teams, scant team-work training, and passive and ill-adapted approaches were seen as restrictions. Training, the coordinator's activities, more meetings and changes in attitude were posed as alternatives.

Attitude of Health Personnel↗
PubMed2001

Acute urinary retention: defining the need and timing for pressure-flow studies.

OBJECTIVE: To investigate the utility of "late" pressure-flow studies in predicting the outcome of prostatectomy for acute urinary retention. PATIENTS AND METHODS: Fifty-eight patients with acute urinary retention were prospectively assessed using the International Prostate Symptom Score and pressure-flow studies at a median (range) of 24 (13-60) days after the episode of retention, and before transurethral resection of the prostate. Bladder outlet obstruction and bladder contractility were graded using a modified adaptation of Schäfer's passive urethral linear resistance relation. RESULTS: Fifty-six (97%) patients generated a voluntary detrusor contraction, with a mean (range) detrusor pressure at maximum flow of 72.7 (5-144) cmH2O, and 43 (75%) patients were deemed to be obstructed. Eight (16%) patients failed to void after prostatectomy and required clean intermittent catheterization. There were statistically significant differences between successful and unsuccessful patients in mean (SD) age, at 66.30 (6.9) vs 78.8 (2.6) years (P = 0.001), detrusor instability (49% vs 0%, P = 0.01), inability to void during pressure study (8% vs 75%, P = 0.001), and maximal detrusor pressure in the voiding phase, at 80 (36.0) vs 19 (11.2) cmH2O (P = 0.001). CONCLUSIONS: In patients with acute urinary retention, pressure-flow studies undertaken after a period of adequate bladder rest (> 3 weeks) are useful in predicting the surgical outcome. Old age, absence of bladder instability, inability to void during the pressure-flow study and a maximal detrusor pressure of < 20 cmH2O are associated with a poor outcome after prostatectomy.

Acute Disease↗
PubMed2002

Molecular evolution of the HoxA cluster in the three major gnathostome lineages.

The duplication of Hox clusters and their maintenance in a lineage has a prominent but little understood role in chordate evolution. Here we examined how Hox cluster duplication may influence changes in cluster architecture and patterns of noncoding sequence evolution. We sequenced the entire duplicated HoxAa and HoxAb clusters of zebrafish (Danio rerio) and extended the 5' (posterior) part of the HoxM (HoxA-like) cluster of horn shark (Heterodontus francisci) containing the hoxa11 and hoxa13 orthologs as well as intergenic and flanking noncoding sequences. The duplicated HoxA clusters in zebrafish each house considerably fewer genes and are dramatically shorter than the single HoxA clusters of human and horn shark. We compared the intergenic sequences of the HoxA clusters of human, horn shark, zebrafish (Aa, Ab), and striped bass and found extensive conservation of noncoding sequence motifs, i.e., phylogenetic footprints, between the human and horn shark, representing two of the three gnathostome lineages. These are putative cis-regulatory elements that may play a role in the regulation of the ancestral HoxA cluster. In contrast, homologous regions of the duplicated HoxAa and HoxAb clusters of zebrafish and the HoxA cluster of striped bass revealed a striking loss of conservation of these putative cis-regulatory sequences in the 3' (anterior) segment of the cluster, where zebrafish only retains single representatives of group 1, 3, 4, and 5 (HoxAa) and group 2 (HoxAb) genes and in the 5' part of the clusters, where zebrafish retains two copies of the group 13, 11, and 9 genes, i.e., AbdB-like genes. In analyzing patterns of cis-sequence evolution in the 5' part of the clusters, we explicitly looked for evidence of complementary loss of conserved noncoding sequences, as predicted by the duplication-degeneration-complementation model in which genetic redundancy after gene duplication is resolved because of the fixation of complementary degenerative mutations. Our data did not yield evidence supporting this prediction. We conclude that changes in the pattern of cis-sequence conservation after Hox cluster duplication are more consistent with being the outcome of adaptive modification rather than passive mechanisms that erode redundancy created by the duplication event. These results support the view that genome duplications may provide a mechanism whereby master control genes undergo radical modifications conducive to major alterations in body plan. Such genomic revolutions may contribute significantly to the evolutionary process.

Amino Acid Motifs↗
PubMed1955

The antibody mechanisms of ragweed allergy; electrophoretic and chemical studies. I. The blocking antibody.

Three human serums containing artificially produced blocking antibody against low ragweed allergen were studied for the possibility of relating blocking antibody to electrophoretically definable components. An adaptation of the qualitative passive transfer test to quantitative interpretation is described, methods and procedures are given and uncertainties and possible errors due to lack of precision and accuracy are presented and discussed. At least 65 per cent, but probably more, if not all of the blocking antibody is attributable to gamma globulin. However, no rise of gamma globulin, either its absolute amount or its relative percentage value, paralleled the appearance of blocking antibody. Blocking antibody is not contained in albumin or in alpha-1 globulin. Blocking effect could not be ascertained unequivocally as being connected with alpha-2 or with beta globulin and sizable participation of these two latter electrophoretic components appears improbable. Blocking antibody and sensitizing antibody appear to be chemically different entities.

Ambrosia↗
PubMed1983

Quality, cost, and clinical decisions.

Clinical decisions require determining the objectives of care as well as selecting and implementing a strategy of care. At the very least the optimal strategy balances the expected benefit and harm from technical interventions. Health care practitioners tend to specify optimal strategies based on what they consider to be best for patients, without regard to monetary cost. This is an absolutist definition of quality. Individuals may place different valuations on the outcomes, are concerned with the monetary costs to themselves, and are particularly sensitive to the attributes of the interpersonal relationship with the practitioners. Including all of these leads to an individualized definition of the quality of care. But this specification of quality may be in conflict with a social definition of quality, which takes into account social as well as individual monetary costs, externalities, and the social distribution of quality. The health care professions may respond to the conflict in several ways, which are described in this article as evasion, rejection and confrontation, anticipation, advocacy, active complicity, passive complicity, and ambiguous adaptations.

Clinical Competence↗
PubMed1999

Effects of general and regional anesthesia on the neonate (a prospective, randomized trial).

UNLABELLED: Anesthetic methods used during cesarean section have advantages and disadvantages to both mothers and infants and may result in short and long term neonatal effects. OBJECTIVE: To determine the effects of general and regional anesthesia on the infants, a prospective, randomized trial was performed in Siriraj Hospital, Mahidol University. MATERIAL AND METHOD: 341 uncomplicated pregnant women who were to be delivered at term by Cesarean section were recruited and randomized to receive general anesthesia, GA (103); epidural anesthesia, EA (120) and spinal anesthesia, SA (118). The immediate fetal and neonatal effects were assessed by cord blood gas analysis and the infant's Apgar scores. The Neurologic and Adaptive Capacity Scores (NACS) was performed within 4 hours after birth by two pediatricians who were blind to the anesthetic method. RESULT: Maternal age, weight, height, duration of the operation and infants' birth weight were not different among the study groups. In the EA and SA group, maternal systolic blood pressure decreased more than 20 per cent from the baseline in more than half. The infants' Apgar scores at 1 and 5 minutes were 8.3 +/- 1.9; 8.2 +/- 1.6; 6.7 +/- 2.8, and 9.7 +/- 0.9; 9.8 +/- 0.7; 9.2 +/- 1.6 in EA, SA and GA group respectively. The adaptive capacity, active tone, passive tone, general assessment and primary reflexes of the NACS were not statistically different. CONCLUSION: Apgar scores of the infants whose mothers received general anesthesia were lower than infants whose mothers received regional anesthesia but the NACS were not statistically different among the three study groups.

Anesthesia, Epidural↗
PubMed1999

IL-12, IFN-gamma, and T cell proliferation to measles in immunized infants.

Measles infection in infants is associated with severe complications, and secondary infections are attributed to generalized immunosuppression. Measles binding to its monocyte receptor down-regulates IL-12 which is expected to diminish Th1-like cytokine responses, including IFN-gamma. Whether young infants can be immunized effectively against measles is an important public health issue. We evaluated Ag-specific IL-12, IFN-gamma, and T cell responses of infants at 6 (n = 60), 9 (n = 46), or 12 mo (n = 56) of age and 29 vaccinated adults. IL-12 and IFN-gamma release by PBMC stimulated with measles Ag increased significantly after measles immunization in infants. IL-12 and IFN-gamma concentrations were equivalent in younger and older infants, but IL-12 concentrations were significantly lower in infants than in adults (p = 0.04). IL-12 production by monocytes was down-regulated by measles; the addition of recombinant human IL-12 enhanced IFN-gamma production by PBMC stimulated with measles Ag, but infant T cells released significantly less IFN-gamma than adult T cells under this condition. Of particular interest, the presence of passive Abs to measles had no effect on the specific T cell proliferation or IFN-gamma production after measles stimulation. Cellular immunity to measles infection and vaccination may be limited in infants compared with adults as a result of less effective IFN-gamma and IL-12 production in response to measles Ags. These effects were not exaggerated in younger infants compared with effects in infants who were immunized at 12 mo. In summary, infant T cells were primed with measles Ag despite the presence of passive Abs, but their adaptive immune responses were limited compared with those of adults.

Adult↗