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Results for “response selection”

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PubMed1984

Selected responses of hypertension-sensitive and resistant rats to inhaled acrolein.

The Dahl selected rat lines, one susceptible to salt-induced hypertension (DS) and the other resistant to salt-induced hypertension (DR), were exposed to filtered air, 0.4, 1.4, or 4.0 ppm acrolein for 6 h/day, 5 days/week for 62 days. All of the DS rats exposed to 4.0 ppm acrolein died within the first 11 days, while 60% of the DR animals survived the duration of the study. Neither dose dependent blood pressure changes nor altered behavioral characteristics were evident in either rat strain following acrolein exposure. Exposure to 4.0 ppm acrolein increased the level of several serum enzymes in the DR rats which survived. This concentration of acrolein also led to pulmonary edema and a significant increase in lung connective tissue in these animals. There was a marked difference in the pulmonary pathology observed in DS and DR rats exposed to 4.0 ppm acrolein. The lungs of moribund DS rats exhibited severe airway epithelial necrosis with edema and hemorrhage, while surviving DR rats primarily showed a proliferative change. Following exposure to 0.4 and 1.4 ppm acrolein, both rat lines displayed similar pathologic changes. Epithelial hyperplasia and/or clusters of macrophages were usually found near terminal bronchiolar areas. These findings suggest that further investigation of the physiopathologic sensitivity of the DS rat line may elucidate a model for investigating the underlying characteristics of stress susceptible populations.

Acrolein↗
PubMed1985

Effects of specific nutrients on the immune response. Selected clinical applications.

The importance of diet in multiple aspects of the immune response is inescapable. Although only a few trials have attempted to apply knowledge derived from in-vitro and animal data to humans, the ability to modulate or "reset" the immune response by manipulating dietary intake will surely continue to be studied in the future. The role of various nutrients in immunity is reviewed and clinical applications are noted.

Adult↗
PubMed1998

Bayesian inference of genetic parameters and selection response for litter size components in pigs.

Three contemporary lines were formed from the progeny of 50 French Large White sows. In the first line, gilts were selected for ovulation rate at puberty. In the second line, they were selected for prenatal survival of the first two parities, corrected for ovulation rate. The control constituted the third line. Ovulation rate at puberty was analyzed using an animal model with a batch effect. Prenatal survival was analyzed with a repeatability animal model that included batch and parity effects. Flat priors were used to represent vague previous knowledge about parity and batch effects. Additive and residual effects were represented assuming that they were a priori normally distributed. Variance components were assumed to follow either uniform or inverted chi-square distributions, a priori. The use of different priors did not affect the results substantially. Heritabilities for ovulation rate ranged from 0.32 to 0.39, and from 0.11 to 0.16 for prenatal survival, depending on the prior used. The mean of the marginal posterior distribution of response to four generations of selection ranged from 0.38 to 0.40 ova per generation, and from 1.1 to 1.3% of the mean survival rate for average survival per generation.

Animals↗
PubMed2002

A novel mechanism of response selectivity of neurons in cat visual cortex.

The spiking of cortical neurons critically depends on properties of the afferent stimuli. In the visual cortex, neurons respond selectively to the orientation and direction of movement of an object. The orientation and direction selectivity is improved upon transformation of the membrane potential changes into trains of action potentials. To address the question of whether the transformation of the membrane potential changes into spiking of a cell depends on the stimulus orientation and the direction of movement, we made intracellular recordings from the cat visual cortex in vivo during presentation of moving gratings of different orientations. We found that the relationship between the membrane polarization and the firing rate (input-output transfer function) depended on the stimulus orientation. The input-output transfer function was steepest during responses to the optimal stimulus; membrane depolarization of a given amplitude led to generation of more action potentials when evoked by an optimal stimulus than during non-optimal stimulation. The threshold for the action potential generation did not depend on stimulus orientation, and thus could not account for the observed difference in the transfer function. Oscillations of the membrane potential in the gamma-frequency range (25-70 Hz) were most pronounced during optimal stimulation and their strength changed in parallel with the changes in the transfer function, suggesting a possible relationship between the two parameters. We suggest that the improved input-output relationship of neurons during optimal stimulation represents a novel mechanism that may contribute to the final sharp orientation selectivity of spike responses in the cortical cells.

Action Potentials↗
PubMed1999

Dopamine-selective response in membrane potential by homooxacalix[3]arene triether host incorporated in PVC liquid membrane.

Selectivities of membrane potential changes for catecholamines and inorganic cations were investigated with lipophilic derivatives of calix[6]arene and related hosts incorporated in poly(vinyl chloride) (PVC) matrix liquid membranes. Homooxacalix[3]arene triether displayed an excellent selectivity for dopamine against other catecholamines (adrenaline, noradrenaline) and also against inorganic cations (K+, Na+).

Dopamine↗
PubMed1979

Conditioned inhibition: selective response of single units.

Single cell activity and local field potentials in parastriate cortex of cats and rabbits were studied during a Pavlovian discrimination procedure. Cell activity was selectively modified; conditioned changes occurred in response either to the reinforced stimulus or to the unreinforced one, but not to both. Cells exhibiting conditioned alteration in response to the unreinforced stimulus are thought to participate in specialized circuits mediating conditioned inhibition.

Action Potentials↗
PubMed1988

Estimates of genetic parameters and predicted selection responses for growth, fat and lean traits in mice.

Heritabilities (ĥ2) and genetic correlations (rG) were estimated by regression of offspring on sire in two replicate, unselected lines of mice. Traits were associated with growth, feed efficiency, fat deposition and lean tissue. The ĥ2 for growth traits ranged from .34 to .42, except for 3-wk body weight, which was only .05. The ĥ2 for feed efficiency was .28. Ranges in ĥ2 were .45 to .50 for fat deposition traits and .36 to .42 for lean tissue traits. The rG involving 3-wk to 6-wk feed efficiency with hind carcass and fat measurements at 12 wk were small. Antagonisms were found between the sign of rG and the direction of usual breeding goals for pairs of traits (e.g., rG greater than 0 between fat deposition and hind carcass weight and rG less than 0 between hind carcass as a percentage of body weight and body weight). Selection indexes were developed to counteract these antagonisms. Modified selection indexes were compared where responses in individual traits rather than the aggregate breeding value were of major importance. The aggregate breeding values and selection indexes included: 1) epididymal fat pad weight and body weight, 2) hind carcass weight and body weight, or 3) all three traits. Economic weights in retrospect were calculated for the modified selection indexes. In some cases, expected correlated responses in component traits were not influenced greatly over a wide range of ratios of economic weights, but in other cases the component traits changed sharply over a narrow range of ratios.

Adipose Tissue↗
PubMed1994

Role of the A/B region of the human mineralocorticoid receptor in aldosterone response selectivity.

In transfection experiments performed with wild-type MR, the maximal transcriptional activation of a mineralocorticoid response induced by glucocorticoid was generally similar to that of aldosterone, the natural mineralocorticoid hormone. However, compared to aldosterone, glucocorticoid activity decreased when the A/B region of MR was absent. We describe in this study the synthesis and biological activities of seven mutated MRs differently truncated in the N-terminal region. Using transient expression conditions in MCF-7 cells, the N-terminal domain of MR has been shown to contain a region (residues 254-390) whose deletion led to an apparent "aldosterone selectivity". These results suggest that this region could help to maintain the most transcriptionally active conformation of MR even in the presence of ligands which are not by themselves able to fully induce such a conformation.

Aldosterone↗
PubMedDate not supplied

Predicting selection response for growth of channel catfish.

Estimates of heritability, phenotypic and genetic correlations were obtained for body length and weight at 5 months and body length and weight at 15 months in channel catfish. The estimates were obtained from a half-sib analysis by mating 20 males to two females each, producing 20 half-sib and 40 full-sib progeny families. Mortality of fish during the study reduced the number of families to 17 half-sib and 34 full-sib. Comparisons of selection methods were made for body length at 5 months and body weight at 15 months. The results of the study show: 1) heritability estimates for body length and weight at 5 months was 0.12 and 0.61, respectively, and body length and weight at 15 months was 0.67 and 0.75, respectively; 2) from the magnitude of the estimates of heritability, it can be inferred that large amounts of additive genetic variance exist in three of the traits (length at 5 months and length and weight at 15 months) and that selection for these traits should be successful; 3) estimates of phenotypic correlation among the four traits ranged from 0.90 to 0.30, and genotypic correlation among the four traits ranged from 1.47 to 0.71; 4) the magnitude and positive nature of the genetic correlations indicated that simultaneous selection for the four traits in channel catfish would be effective; and 5) comparisons of predicted response under individual, indirect and index selection, show that selection on an index based on all four traits gives maximum response in length at 5 months and weight at 15 months.

Animals↗
PubMed1999

Virus-specific cytotoxic T-lymphocyte responses select for amino-acid variation in simian immunodeficiency virus Env and Nef.

Cytotoxic T-lymphocyte (CTL) responses to human immunodeficiency virus arise early after infection, but ultimately fail to prevent progression to AIDS. Human immunodeficiency virus may evade the CTL response by accumulating amino-acid replacements within CTL epitopes. We studied 10 CTL epitopes during the course of simian immunodeficiency virus disease progression in three related macaques. All 10 of these CTL epitopes accumulated amino-acid replacements and showed evidence of positive selection by the time the macaques died. Many of the amino-acid replacements in these epitopes reduced or eliminated major histocompatibility complex class I binding and/or CTL recognition. These findings strongly support the CTL 'escape' hypothesis.

Amino Acid Sequence↗
PubMed2002

[N2 effect on non-target event-related brain potentials during auditory selective response task].

Objective. To study N2 effect and its feature on non-target event-related brain potentials during auditory selective attention. Method. The subjects were 16 healthy right-handed male volunteers aged 23.2 +/- 2.1 years. The stimuli were male voice of one-digit numbers (2 to 7), which were single syllable pronunciated in Chinese, and appeared randomly with equal probability. The subjects were asked to press a switch as soon as the target signal (odd or even number) was heard but make no response to the non-target signal. EEG signals at 9 locations were recorded. Result. 1) A negative component N280 (N2 effect) was found after non-target stimuli as compared to target stimuli, which was significant in the frontal brain locations; 2) P3 was smaller and its peak appeared later in non-target ERPs than in target ERPs. Conclusion. N2 effect was also elicited by non-target stimuli during auditory modality. We assume that N2 effect might reflect the readjusting of model stored in working memory at the frontal brain.

Adult↗
PubMed2002

Indomethacin causes prostaglandin D(2)-like and eotaxin-like selective responses in eosinophils and basophils.

We investigated the actions of a panel of nonsteroidal anti-inflammatory drugs on eosinophils, basophils, neutrophils, and monocytes. Indomethacin alone was a potent and selective inducer of eosinophil and basophil shape change. In eosinophils, indomethacin induced chemotaxis, CD11b up-regulation, respiratory burst, and L-selectin shedding but did not cause up-regulation of CD63 expression. Pretreatment of eosinophils with indomethacin also enhanced subsequent eosinophil shape change induced by eotaxin, although treatment with higher concentrations of indomethacin resulted in a decrease in the expression of the major eosinophil chemokine receptor, CCR3. Indomethacin activities and cell selectivity closely resembled those of prostaglandin D(2) (PGD(2)). Eosinophil shape change in response to eotaxin was inhibited by pertussis toxin, but indomethacin- and PGD(2)-induced shape change responses were not. Treatment of eosinophils with specific inhibitors of phospholipase C (U-73122), phosphatidylinositol 3-kinase (LY-294002), and p38 mitogen-activated protein kinase (SB-202190) revealed roles for these pathways in indomethacin signaling. Indomethacin and its analogues may therefore provide a structural basis from which selective PGD(2) receptor small molecule antagonists may be designed and which may have utility in the treatment of allergic inflammatory disease.

Antigens, CD↗
PubMed1994

Selective response of human airway epithelia to luminal but not serosal solution hypertonicity. Possible role for proximal airway epithelia as an osmolality transducer.

The response of cultured human nasal epithelia to hypertonic bathing solutions was tested using ion-selective microelectrode and quantitative microscopy. Raised luminal, but not serosal, osmolality (+/- 150 mM mannitol) decreased Na+ absorption but did not induce Cl- secretion. Raised luminal osmolality increased cell Cl- activity, Na+ activity, and transepithelial resistance and decreased both apical and basolateral membrane potentials and the fractional resistance of the apical membrane; equivalent circuit analysis revealed increases in apical, basolateral, and shunt resistances. Prolonged exposure (10 min) to 430 mosM luminal solution elicited no regulation of any parameter. Optical measurements revealed a reduction in the thickness of preparations only in response to luminal hypertonic solutions. We conclude that (a) airway epithelial cells exhibit asymmetric water transport properties, with the apical membrane water permeability exceeding that of the basolateral membrane; (b) the cellular response to volume loss is a deactivation of the basolateral membrane K+ conductance and the apical membrane Cl- conductance; (c) luminal hypertonicity slows the rate of Na+ absorption but does not induce Cl- secretion; and (d) cell volume loss increases the resistance of the paracellular path. We speculate that these properties configure human nasal epithelium to behave as an osmotic sensor, transducing information about luminal solutions to the airway wall.

Adult↗
PubMed2003

On the interaction between perceptual and response selection: neuropsychological evidence.

We examined the relations between selection for perception and selection for action in a patient FK, with bilateral damage to his temporal and medial frontal cortices. The task required a simple grasp response to a common object (a cup) in the presence of a distractor (another cup). The target was cued by colour or location, and FK made manual responses. We examined the effects on performance of cued and uncued dimensions of both the target and the distractor. FK was impaired at perceptually selecting the target when cued by colour, when the target colour but not its location changed on successive trials. The effect was sensitive to the relative orientations of targets and distractors, indicating an effect of action selection on perceptual selection, when perceptual selection was weakly instantiated. The dimension-specific carry-over effect on reaching was enhanced when there was a temporal delay between a cue and the response, and it disappeared when there was a between-trial delay. The results indicate that perceptual and action selection systems interact to determine the efficiency with which actions are selected to particular objects.

Adult↗
PubMed2005

Selection responses in duration of fertility and its consequences on hatchability in the intergeneric crossbreeding of ducks.

1. From 1992 to 2003, selected (S) and control lines (C) of the laying Brown Tsaiya duck (Anas platyrhynchos) were simultaneously maintained under the same standardised conditions of feeding and management. 2. The selection objective was to increase the number of fertile eggs after a single artificial insemination (AI) with pooled Muscovy semen. From generations G1 to G11, 2452 and 2022 female ducks, in S and C lines, respectively, were measured and recorded. In the S line, the percentage selected varied between 20.2 and 34.3% in females and between 7.2 and 20.8% in males. 3. Selection for number of fertile eggs had a correlated effect of increasing the parameter tau of the logistic curves which fitted the daily variations (d 2 to 15) in fertility or hatchability on the basis of eggs set. The differences S-C for the estimates of the times of half maximal fertility and hatchability increased by 0.41 and 0.37 d per generation between G1 and G11, respectively. 4. The highest increases of fertility per day rates after a single AI were observed between d 5 and 11. Moreover, in the selected line, fertility rate was higher than, or equal to, 90% in d 2 from G8. The same tendencies were observed for the changes in the evolution of hatchability on the basis of eggs set. 5. Selection increased fertility and hatchability according to the egg set rates, especially for d 2 to 8 after AI. Hatchability of fertile eggs was not impaired, confirming that selection for one AI per week was possible in this strain of laying ducks.

Animal Husbandry↗
PubMedDate not supplied

Selective response of various brain cell types during neurodegeneration induced by mild impairment of oxidative metabolism.

Age-related neurodegenerative diseases are characterized by selective neuron loss, glial activation, inflammation and abnormalities in oxidative metabolism. Thiamine deficiency (TD) is a model of neurodegeneration induced by impairment of oxidative metabolism. TD produces a time-dependent, selective neuronal death in specific brain regions, while other cell types are either activated or unaffected. TD-induced neurodegeneration occurs first in a small, well-defined brain region, the submedial thalamic nucleus (SmTN). This discrete localization permits careful analysis of the relationship between neuronal loss and the response of other cell types. The temporal analysis of the changes in the region in combination with the use of transgenic mice permits testing of proposed mechanisms of how the interaction of neurons with other cell types produces neurodegeneration. Loss of neurons and elevation in markers of neurodegeneration are accompanied by changes in microglia including increased redox active iron, the induction of nitric oxide synthase (NOS) and hemeoxygenase-1, a marker of oxidative stress. Endothelial cells also show changes in early stages of TD including induction of intracellular adhesion molecule-1 (ICAM-1) and endothelial NOS. The number of degranulating mast cells also increases in early stages of TD. Alterations in astrocytes and neutrophils occur at later stages of TD. Studies with transgenic knockouts indicate that the endothelial cell changes are particularly important. We hypothesize that TD-induced abnormalities in oxidative metabolism promote release of neuronal inflammatory signals that activate microglia, astrocytes and endothelial cells. Although at early stages the responses of non-neuronal cells may be neuroprotective, at late phases they lead to entry of peripheral inflammatory cells into the brain and promote neurodegeneration.

Animals↗
PubMed1994

Hippocampal lesions impair spatial response selection in the primate.

This study investigates the role of the primate hippocampus in spatial cognition. Following lesions to the hippocampus, monkeys were unable to learn to direct their responses to different locations in space, based on a spatial cue. This deficit was not due to an impairment in learning to make the responses, since lesioned monkeys were normal when these did not have to be spatially selective. Furthermore, the deficit could not have been due to an impairment in the detection of cues, since lesioned monkeys were normal in their ability to detect visual targets presented over a wide area of space. These results support the view that the hippocampus of the monkey is necessary in order to remember the spatial arrangement of visual scenes in an egocentric manner.

Animals↗
PubMed1998

[A study on the response selection and inhibition in a cognitive conflict task using event-related potentials].

This study examined the hypothesis (Eriksen & Schultz, 1979) that a subject checks whether a prepared response is correct or not in the Eriksen and Eriksen (1974) cognitive conflict task, using event-related potentials (ERPs). Fourteen right-handed subjects were required to respond selectively to a central target letter flanked with compatible (e.g., HHHHHHH) or incompatible (e.g., SSSHSSS) noise letters, or not to respond to asterisks (*******). The results showed that the lateralized readiness potential indicating an incorrect preparation and the NO-GO potential reflecting a response inhibition emerged for incompatible stimuli. These findings indicate that a prepared response was recognized as erroneous, and was inhibited. Therefore, it is suggested that the check operation functioned in the cognitive conflict task. Furthermore, the result that the NO-GO potential latency for incompatible stimuli was longer than that for NO-GO stimuli suggests that the timing of NO-GO decision and response inhibition by the check operation influenced the NO-GO potential latency.

Adult↗