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At least 505 records · Page 28Linked to original sources
PubMed2001

Rats with basolateral amygdala lesions show normal increases in conditioned stimulus processing but reduced conditioned potentiation of eating.

Rats with neurotoxic lesions of basolateral amygdala (ABL) and control rats showed comparable enhancement of attentional processing of a visual stimulus when its predictive value was altered. In contrast, lesioned rats showed less potentiation of eating than did control rats when food was available during presentations of a conditioned stimulus that was previously paired with food. When considered together with previous data, these results indicate a double dissociation between effects of lesions of the ABL and of the amygdala central nucleus on phenomena related to attentional processing and the acquisition of motivational value.

Amygdala↗
PubMedDate not supplied

[Effect of piracetam on the conditional reflex memory under probable reinforcement conditions].

The effect of piracetam on the development of a two-link system of feed-procuring conditioned reflexes was studied in rats with probability reinforcement. The experiments showed that piracetam improves both the current learning process and the memory track (previous experience) reproduction. In addition, the drug decreases the role of the probabilic character of reinforcement, thus facilitating the synthesis of two reflexes in a united functional complex.

Animals↗
PubMed1987

[Changes in the protein level in rat hippocampal neurons during development of the alimentary conditioned reflex under normal conditions and after treatment with iproniazid].

The protein content in neurons of areas CA-1 and CA-3 of the dorsal hippocampus has been determined by means of cytointerferometry in rats during elaboration of unlocal alimentary instrumental reflex (ULAIR) and local alimentary instrumental reflex (LAIR) on the background of increased and normal serotonine content in the brain. It has been found that during the ULAIR elaboration the hippocampal neurons react by an increase of dry mass, during the LAIR elaboration-by its decrease. Under condition of serotonine excess in the brain the changes of dry mass in hippocampal neurons during elaboration of the two reflexes are opposite to these observed during the ULAIR and LAIR elaboration with normal serotonine content.

Animals↗
PubMedDate not supplied

[The formation of conditioned reflexes to a complex signal in ontogeny under the conditions of an alternation choice].

Formation of conditioned reflex to simultaneous complex stimulus (light + sound) and its components was studied in alternation task (Go/Go) in kittens aged 1.5-10 months. Low percentage of correct reactions (48-57%) and preference of one of the two reinforced directions were shown in kittens aged 1.5-5 months. Successful learning in alternation task was attained in kittens which began to be trained at the age of 6 months. Extirpation of sensorimotor cortex in the trained animals aged 7 months and older induced a decrease of the level of correct reactions from 75-80% to 20-40% and preference of one direction. The problems of parallel development of interaction between the sensory and motor systems and sensorimotor cortex are discussed.

Acoustic Stimulation↗
PubMedDate not supplied

[An evaluation of the high-frequency components in the EEG reactions to positive and differentiated conditional stimuli in motor-food conditioned reflexes in dogs].

EEG reactions to positive and differentiated signals were compared during lever-pressing alimentary conditioning in dogs by means of described by us earlier non-standard forms of EEG analysis in a wide frequency band (1-256 Hz). Findings concerning EEG reactions to positive stimuli, confirmed the earlier obtained data on a high representativeness of the high-frequency components of dog's EEG. EEG reactions to differentiated stimuli were also excitatory. Developed by us techniques allowed us to show some quantitative characteristics of these reactions. Diversity of expression of high-frequency components in different dogs, accompanied by similarity of their effector reactions (absence of movement), was considered as a reflection of individual features of their CNS.

Acoustic Stimulation↗
PubMedDate not supplied

[The realization of a conditioned avoidance reflex in rats under conditions of the multiple activation of the globus pallidus dopaminergic system].

Daily bilateral microinjections of 15 or 45 mcg of amphetamine into the globus pallidus of rats within three weeks inhibited the realization of conditioned avoidance in a shuttle-box. The dose of 15 mcg was most effective. There were no changes in locomotor activity. In contrast to the results obtained earlier in the experiments with similar neostriatal microinjections, no stimulatory dopaminergic effects (stereotyped behavior) were observed. The differences are discussed in the roles of the pallidal and neostriatal dopaminergic systems in regulation of behavior.

Amphetamine↗
PubMed2005

Distribution of calcium ions in the mixed synapses of Mauthner neurons in the goldfish in normal conditions, in exhaustion, and in conditions of adaptation to exhaustion.

The aim of this study was to investigate the structure of large myelinated club terminals of Mauthner neurons (MN) in the goldfish at different levels of functional activity and the distribution within these synapses of calcium ions as assessed using a modified pyroantimonate method. In intact preparations, calcium pyroantimonate precipitates were not seen in gap junctions (GJ) or desmosome-like contacts (DLC). Fibrillar bridges in DLC clefts were not contrasted. After natural stimulation, which induces long-term adaptation in MN, GJ showed electron-dense precipitates lining the whole cleft. Granules and clumps of precipitate were also seen in DLC clefts, with intense deposition on bridges. Increases in calcium ion concentrations to and above the levels detectable by the pyroantimonate method are known to block electrotonic transmission; filamentous actin is known to conduct the electrotonic signal as a cation current. The staining of DLC bridges with calcium pyroantimonate is therefore evidence for an association between calcium ions and actin molecules, as DLC bridges consist of actin, i.e., we have obtained evidence for the functioning of bridges as electrotonic transsynaptic shunts at the moment of fixation. These data lead to the conclusion that DLC in mixed synapses, apart from the known adhesive functions, also have a communication function. This appears in extreme conditions, allowing the synapse to maintain or change its conductivity according to ongoing need.

Acclimatization↗
PubMed1990

Identification of conditioned medium proteins from human cancer cells adapted to serum-free conditions.

Recent studies have shown that human cancer cell lines can be adapted to grow in serum-free, unsupplemented RPMI-1640 (RO) medium. We have developed similar techniques to rapidly identify proteins of interest in serum-free conditioned medium (CM) of human lung cancer cell lines. Classic and variant small cell lung cancer (SCLC) lines were adapted to growth in RO medium. CM from each line was concentrated and fractionated on an anion-exchange column of a fast protein liquid chromatography system. Concentrates of each fraction were loaded onto lanes of minigels of an automated electrophoresis system. Analysis of the chromatograms reveals peaks seen only in CM of the classic SCLC lines. Electrophoretic analysis of the fractions containing these peaks reveal protein bands distinguishing between the subtypes of human SCLC. One protein was purified to homogeneity with subsequent reversed-phase chromatography and identified by protein microsequencing as histone H2B. These automated techniques have general use in the rapid identification of CM proteins associated with the differentiation or progression of the many types of neoplastic cells which can be adapted to growth in RO medium.

Amino Acid Sequence↗
PubMed1994

Comprehensive care of the child with a chronic condition. Part 1. Understanding chronic conditions in childhood.

Understanding the care of children with chronic illnesses and disabilities is an important part of the practice of pediatrics. Children with special health care needs and their families benefit from the support which comprehensive, coordinated, accessible, and responsive services provide. Although the primary care pediatrician is often most appropriate to serve as the overall coordinator of such services, many challenges to providing such care exist. Part 2, "Primary Care Management," will suggest guiding principles and management structures that allow the pediatrician to respond most effectively over time to the needs of children with chronic conditions and their families.

Child↗
PubMed1984

Urinary excretion of 2,3-dinor-thromboxane B2 in man under normal conditions, following drugs and during some pathological conditions.

Quantitation of 2,3-dinor-thromboxane B2 (2,3-dinor-TxB2) was performed by gas chromatography-mass spectrometry. Under normal conditions the urinary excretion of 2,3-dinor-TxB2 was relatively constant in the same individual from day to day but during a 24-hour period a somewhat higher excretion rate was found during the first few hours after awakening. A pronounced reduction of the urinary excretion of 2,3-dinor-TxB2 was found after oral administration of 500 mg of aspirin or 50 mg of indomethacin, while 500 mg of paracetamol did not affect the urinary excretion. Increased excretion of 2,3-dinor-TxB2 was found in normal pregnancies and in diseases such as diabetes mellitus and homocysteinuria in comparison to the urinary excretion in normal healthy subjects. We also report one case, where the urinary excretion of 2,3-dinor-TxB2 was increased for a short period following the first symptoms of a myocardial infarction and those data indicate that thromboxane A2 (TxA2) may be of pathophysiological importance in human myocardial infarction. The results strongly indicate that measurements of the urinary excretion of 2,3-dinor-TxB2 should be meaningful as a tool for investigation of the involvement of thromboxane in various pathophysiological processes in vivo in man.

Acetaminophen↗
PubMed1987

Quantitative studies of steroid bioconversions in the seminal vesicles of spawning male African catfish, Clarias gariepinus (Burchell), under natural conditions, and of non-spawning catfish under natural and fish farm conditions.

1. Steroid bioconversions in the seminal vesicles of Clarias gariepinus were studied quantitatively in vitro by tissue incubations with [3H]pregnenolone, [3H]androstenedione and [14C]11 beta-hydroxyandrostenedione, respectively. 2. Spawning and non-spawning catfish, collected in the Hula nature reserve in northern Israel during the spawning period, and non-spawning animals, collected from a fish pond in the same region during the same period, were studied. 3.Spawning animals showed a significantly higher production of 17 alpha-hydroxyprogesterone, 5 beta-pregnan-17 alpha-ol-3,20-dione and 5 beta-reduced androgens than non-spawning feral and pond catfish, as a result of a significantly increased contribution of the enzymes 5 beta-reductase and 3 alpha-hydroxysteroid dehydrogenase (HSD). 4. In spawning catfish the concentration of gonadotropin in blood plasma were also significantly higher than in the plasma of non-spawning feral and pond catfish. This increase in gonadotropin level might have induced the rise in enzyme activity of 5 beta-reductase and 3 alpha-HSD. 5. It is concluded that the absence of a shift in steroidogenesis towards the production of 5 beta-reduced steroids may be among the factors preventing spontaneous spawning in male African catfish under husbandry conditions.

Androstenedione↗
PubMed2004

The potential of the lichen symbiosis to cope with the extreme conditions of outer space II: germination capacity of lichen ascospores in response to simulated space conditions.

Complementary to the already well-studied microorganisms, lichens, symbiotic organisms of the mycobiont (fungi) and the photobiont (algae), were used as "model systems" in which to examine the ecological potential to resist to extreme environments of outer space. Ascospores (sexual propagules of the mycobiont) of the lichens Fulgensia bracteata, Xanthoria elegans and Xanthoria parietina were exposed to selected space-simulating conditions (up to 16 h of space vacuum at 10(-3) Pa and UV radiation at 160 nm < or = lambda < or = 400 nm), while embedded in the lichen fruiting bodies. After exposure, the ascospores were discharged and their viability was tested as germination capacity on different culture media including those containing Mars regolith simulant. It was found that (i) the germination rate on media containing Mars regolith simulant was as high as on other mineral-containing media, (ii) if enclosed in the ascocarps, the ascospores survived the vacuum exposure, the UV-irradiation as well as the combined treatment of vacuum and UV to a high degree. In general, 50 % or more viable spores were recovered, with ascospores of X. elegans showing the highest survival. It is suggested that ascospores inside the ascocarps are well protected by the anatomical structure, the gelatinous layer and the pigments (parietin and carotene) against the space parameters tested.

Ascomycota↗
PubMed2005

Release dynamic process identification for a cement based material in various leaching conditions. Part I. Influence of leaching conditions on the release amount.

In this paper we investigate at laboratory scale the influence of the liquid/solid leaching conditions on the release of different chemical species from a reference porous material obtained by solidification of PbO and CdO with Portland cement. The pH influence on the dissolution of pollutants and the initial pore solution composition (target elements: Na(+), K(+), Ca(2+), Pb(2+), Cd(2+), SO(4)(2-)) were assessed by applying a methodology consisting of two equilibrium leaching tests, the Acid Neutralization Capacity (ANC) and the Pore Water (PW) tests and geochemical modelling. Samples of the same material were submitted in parallel to four different dynamic leaching tests in order to determine the influence of the sample shape (monolithic or granular) and eluate hydrodynamics (instantaneous L/S ratio, eluate renewal) on the leaching of the target elements. The comparison criteria were the eluate saturation state, the cumulative release and the released flux. Generally, the eluates obtained in the tests applied on granular material were more concentrated, even saturated for the eluate pH value with respect to Ca(2+), Pb(2+) and SO(4)(2-). The consequence of the eluate saturation is the slowing down effect on the dynamic release. The highest released flux was observed for the Monolith Leaching Test (MLT) involving the highest instantaneous L/S ratio and the lowest solid/liquid exchange surface and for which no saturation was observed, except Pb(2+) and SO(4)(2-) in some eluates. The maximum cumulative released-mass was obtained for the Column Leaching Test (CLT) applied on granular material having the highest exchange surface, the lowest instantaneous L/S and a continuous input flow of the leachant. The experimental results demonstrate the significance of the liquid/solid contact type which is also a scenario specific parameter.

Calcium↗
PubMed2001

Low-frequency physical activity insufficient for aerobic conditioning is associated with lower body fat than sedentary conditions.

We aimed to show the relationships between reported physical activity, fitness level, and body composition in healthy adult office-working Kuwaiti males (n = 45). Reported level of physical activity (group 0 = no routine exercise, n = 10; group 1 = routine exercise once per wk, n = 19; group 2 = routine exercise two or more times per wk, n = 16) was determined from recall questionnaires. Aerobic fitness levels were assessed from resting exercise heart rates and measurement of maximal oxygen uptake (treadmill exercise, Bruce protocol). Body composition was estimated from measurements of body weight, body height, and seven skin-folds. None of the subjects reported dieting to reduce or maintain their body weight. Despite minimal and not statistically significant differences in resting heart rates, VO(2)max, VO(2)max/kg body weight, and VO(2)max/kg lean body mass, the sedentary group (group 0) had a much higher (12--14 kg) average body weight, higher (12--13 kg) body fat, and thicker skin folds than the more physically active groups 1 and 2. Groups 1 and 2 did not differ significantly from each other with regard to fitness and body composition parameters. Thus, routine physical activities insufficient to result in aerobic conditioning were found to be associated with lower body weight and lower body fat compared to those present in subjects reporting the total absence of any routine physical activity. These data are consistent with the hypothesis that even mild levels of routine physical activity are associated with levels of energy turnover that allow less intense and/or frequent periods of positive energy balance, resulting in maintenance of lower body fat than in totally sedentary people. Frequency of participation in routine physical activities may also reflect the level of non-exercise related physical activities and thus relate to the ability to minimize weight gain.

Adipose Tissue↗