Effects of drugs on concurrent variable-interval variable-interval schedule performance

INTRODUCTION: Telomerase is an enzyme that is required for maintenance of telomeres. This enzyme has been shown to be present in germline tissues and majority of tumors and tumor cell lines. The regulation of telomerase is an area of active investigation in different models because, potentially, inhibition of this enzyme could be important in cancer therapy. To study the regulation of this enzyme in lymphoma cell lines, we used DMSO to produce a reversible G0/G1 arrest in Raji cell line, as shown earlier [Sawai M, Takase K, Teraoka H, Tsukada K. Reversible G1 arrest in the cell cycle of human lymphoid cell lines by dimethyl sulphoxide. Exp Cell Res 1990;187:4-10]. METHODS: In this study, we use a highly quantifiable conventional (non-amplified) assay to study the effect of DMSO on telomerase. In addition, we studied cellular proliferation and cell cycle profiles of the cells treated and, subsequently, released from DMSO induced blockage. RESULTS: In this model, DMSO reversibly inhibited telomerase activity that could be restored after release from the blockage. The inhibition of telomerase seems to parallel cellular proliferation and it appears that telomerase is regulated upon entry into the cell cycle. This view is consistent with other previously published views on relationship of telomerase with exit from cell cycle. CONCLUSION: Our observations demonstrate a novel effect of DMSO on cellular mechanisms in Raji cell line. It may provide an attractive model to further study regulation of telomerase in this cell line.     

Key-peck probability and topography in a concurrent variable-interval variable-interval schedule with food and water reinforcers

The relation between variables that modulate the probability and the topography of key pecks was examined using a concurrent variable-interval variable-interval schedule with food and water reinforcers. Measures of response probability (response rates, time allocation) and topography (peck duration, gape amplitude) were obtained in 5 water- and food-deprived pigeons. Key color signaled reinforcer type. During baseline, response rates and time allocations were greater to the food key than to the water key, and food-key pecks had larger gapes and shorter durations. Relative probability measures (for the food key) were increased by prewatering and decreased by prefeeding. Deprivation effects upon topography measures were apparent only when food- and water-key pecks were analyzed separately. Food-key gape amplitudes increased with prewatering and decreased with prefeeding. The clearest effect occurred with prewatering. There were no consistent effects upon water-key gapes. The key color-reinforcer relation was reversed for 3 pigeons to determine how response topography was modulated during the transition from food- to water-key pecks. Reacquisition was faster for the probability than for the topography measures. Analysis of gape-amplitude distributions during reversal indicated that response-form modulation proceeded through the generation of intermediate gape sizes.     

An analysis of changes in performance quality with operant conditioning procedures.

Applied operant conditioning procedures to 160 male undergraduates performing a routine, repetitive task to investigate the effectiveness of these procedures in obtaining changes in performance quality (and quantity) over time. Results indicate that (a) when the response-reinforcement contingency was shifted from emphasis on quantity to quality, behavior was not changed significantly by either verbal or monetary reinforcers. (b) During contingency shifts from quality to quantity, overt performance changed significantly using either reinforcer quality falling from high to low levels and quantity mounting from low to high levels. (c) As an effective behavioral change agent, the verbal reinforcer was either equal to or greater than the monetary reinforcer. (d) Shifting the contingency from quality to quantity yielded greater performance changes than shifting from quantity to quality. (e) Conditioning procedures, when compared to an absence of conditioning, facilitated higher levels of performance and maintenance of these higher levels over time. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Sucrose, ethanol, and sucrose/ethanol reinforced responding under variable-interval schedules of reinforcement

Adding sweeteners to ethanol solutions is a common method of inducing rats to consume ethanol. However, it has usually been assumed that it is the sweet taste and/or the calories contained in the sweet solution that controls consumption. The present experiment examined the role of ethanol in controlling responding reinforced by ethanol or an ethanol/sucrose mixture compared with sucrose solutions of various concentrations. After initiation to self-administer 10% (v/v) ethanol using the sucrose-substitution method, rats were trained to respond under a concurrent VI 5" VI 5" schedule. During one condition, responding on one lever was reinforced by the presentation of 10% ethanol, and responding on a second lever was reinforced by water or one of the following sucrose solutions: 1% (w/v), 1.5%, 2%, 2.5%, 3%, and 5%. During a subsequent condition, responding reinforced by a 10% ethanol/2% sucrose mixture was compared under the concurrent schedule with responding reinforced by water, 2%, 2.5%, 3%, 5%, or 10% sucrose (w/v). The results indicated that the ethanol or ethanol/sucrose mixture maintained more responding than did sucrose solutions that were sweeter. Data support the conclusion that, after initiation, the taste and/or pharmacological effects of ethanol had become an important component of the reinforcing stimulus independent of the sweetener.     

Facilitation of acquisition and performance of operant and spatial learning tasks in self-stimulation experienced rats.

Adult male Wistar rats were implanted bilaterally with bipolar electrodes in substantia nigra-ventral tegmental area (SN-VTA) to experience intracranial self-stimulation (ICSS) for 15 min per day over a period of 10 days. These rats were then assessed for the acquisition and performance of the operant and the spatial learning tasks. ICSS experienced rats showed rapid acquisition of both the operant and the spatial learning tasks. Both the lever press performance for 7 sessions in the operant learning task and mean number of alternations per session in the spatial learning task were significantly higher (p?     

Reinforced variability and operant learning.

Reinforcement of variability may help to explain operant learning. Three groups of rats were reinforced, in different phases, whenever the following target sequences of left (L) and right (R) lever presses occurred: LR, RLL, LLR, RRLR, RLLRL, and in Experiment 2, LLRRL. One group (variability [VAR]) was concurrently reinforced once per minute for sequence variations, a second group also once per minute but independently of variations, that is, for any sequences (ANY), and a control group (CON) received no additional reinforcers. The 3 groups learned the easiest targets equally. For the most difficult targets, CON animals' responding extinguished whereas both VAR and ANY responded at high rates. Only the VAR animals learned, however. Thus, concurrent reinforcers—contingent on variability or not—helped to maintain responding when difficult sequences were reinforced, but learning those sequences depended on reinforcement of variations. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Effects of amperozide, 8-OH-DPAT, and FG 5974 on operant responding for ethanol

Ventilatory acclimatization to sustained hypoxia (VASH) is the time-dependent increase in ventilation that occurs during prolonged exposure to hypoxia. We tested the hypothesis that carotid body (CB) dopaminergic mechanisms are down-regulated during VASH, which would allow CB afferent discharge and ventilation to increase beyond the initial response to hypoxia. Domperidone (DOM; 1.0 mg.kg-1) was administered intravenously to block CB dopamine (DA) receptors after VASH was complete in awake goats. DOM caused a significant augmentation of the ventilatory response to hypoxia in acclimatized goats, failing to support the hypothesis. We conclude that inhibitory CB dopaminergic function is not significantly reduced following prolonged hypoxia, and that down-regulation of CB dopaminergic mechanisms may not be involved in VASH in the goat.     

Factored life history antecedents of industrial research performance.

The purpose of this study was to better comprehend underlying, discriminating personal characteristics represented in a population of 418 petroleum research scientists. 5 factors were extracted from a matrix of 75 discriminating life history items and 3 criteria of research performance. The factors were tentatively identified as Favorable Self-Perception, Inquisitive, Professional Orientation, Utilitarian Drive, Tolerance for Ambiguity, and General Adjustment. Profiles of the 3 criterian groups across the 5 factors revealed great similarity between the profiles based on ratings, but substantial differences between these and the patent disclosures profile. The observed differences were interpreted in terms of their implications for distinctive personnel policies. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

珠江钢厂规划变迁

本文叙述广州市冶金工业公司1986年计划将广州轧钢厂移地扩建成年产30万吨钢棒线材产品的珠江钢厂,规划经多次变更,到1993年6月国家批准珠江钢厂采用薄板坯连铸连轧新工艺,年产80万吨钢的热轧带钢厂,于1999年8月建成投产的规划演变过程。     

The effects of handedness, family history and sex on the performance of a dichotic listening task

The action of some drugs on the eye may lead to the occurrence of unforeseen ocular and extraocular reactions. Vincaleukoblastin (Velbe) provokes serious corneal lesions with a healing time of two weeks and a half. The local application of Neo-Synephrine eye drops (10%) and Mydrial-Atropine ointment may lead in the case of a pharmacogenetic disposition to disagreeable systemic effects. In one case of preparation for a cataract operation by akinesis and retrobulbar injection, Novocain was changed by mistake with Pilocarpinum hydrochloricum by the error of a pharmaceutical firm. This led to severe complications, which could by successfully treated with Chlorpromazine (Largactil). The knowledge of these clinical observations may be of greater usefulness in the preventation of untoward drug reactions.     

Catecholamines and operant response rates in albino rats

Rabbit aortic strips (nerve-free, reserpine-pretreated or normal) whose noradrenaline-metabolizing enzymes were inhibited (by in vitro treatment with 0.5 mM pargyline for 30 min and by the presence of 0.1mM U-0521) were exposed to 1.18 muM labelled (-)- or (+)noradrenaline for 30 min. At the end of the incubation period some strips were used for analysis of radioactive (i.e., of noradrenaline and its metabolites), while for others the efflux of radioactivity was determined during 250 min of wash out with amine-free solution. An estimate of the original distribution of the amine into the various extraneuronal and neuronal compartments of the tissue was obtained by compartmental analysis of the efflux curves. 1. The mechanisms responsible for the accumulation of radioactivity in extraneuronal and axoplasmic compartments lack stereoselectivity; the rate constants for the efflux of radioactivity from these compartments are the same for (-)- and (+)noradrenaline. 2. The accumulation of radioactivity in storage vesicles is stereospecific with preference for the (-)isomer. 3. Despite the use of enzyme inhibitors, the "late neuronal efflux" of radioactivity (i.e., the efflux collected between the 200th and 250th min of wash out) contained a considerable proportion of metabolites of noradrenaline. The metabolism of noradrenaline was stereoselective: while dihydroxyphenylglycol (DOPEG) was the predominant metabolite in the efflux from strips incubated with (-)noradrenaline, a considerable part of the efflux from strips incubated with the (+) isomer consisted of dihydroxymandelic acid and "O-methylated and deaminated" metabolites (in addition to DOPEG).     

Acquisition, retention, and extinction of operant discriminations in rats with nucleus basalis magnocellularis lesions.

Effects of bilateral ibotenic acid lesions of nucleus basalis magnocellularis (NBM) and scopolamine treatment on different aspects of learning and memory in an operant discrimination task were assessed. In Experiment 1, NBM lesions impaired acquisition performance. In Experiment 2, scopolamine lowered response rates but did not affect discrimination accuracy in lesioned or control rats. In Experiment 3, although pretrained rats showed transient increases in commission errors, percentage correct responding remained above chance levels after lesion. During extinction in Experiment 4, operant responding diminished more quickly in pretrained NBM-lesioned rats than in controls, but subsequent reacquisition performance was equivalent in both groups. Results suggest the NBM is importantly involved in discrimination learning, but cholinergic activity may be less critical for memory retention than for acquisition. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

A comparison of adult and adolescent rat behavior in operant learning, extinction, and behavioral inhibition paradigms.

Poor self-control, lack of inhibition, and impulsivity contribute to the propensity of adolescents to engage in risky or dangerous behaviors. Brain regions (e.g., prefrontal cortex) involved in impulse-control, reward-processing, and decision-making continue to develop during adolescence, raising the possibility that an immature brain contributes to dangerous behavior during adolescence. However, very few validated animal behavioral models are available for behavioral neuroscientists to explore the relationship between brain development and behavior. To that end, a valid model must be conducted in the relatively brief window of adolescence and not use manipulations that potentially compromise development. The present experiments used three operant arrangements to assess whether adolescent rats differ from adults in measures of learning, behavioral inhibition, and impulsivity, within the aforementioned time frame without substantial food restriction. In Experiment 1, separate squads of rats were trained to lever-press and then transitioned to two types of extinction. Relative to their baselines, adolescent rats responded more during extinction than adults, suggesting that they were less sensitive to the abolishment of the reinforcement contingency. Experiment 2 demonstrated similar age-related differences during exposure to a differential reinforcement of low rates schedule, a test of behavioral inhibition. Lastly, in Experiment 3, adolescent's responding decreased more slowly than adults during exposure to a resetting delay of reinforcement schedule, suggesting impaired self-control. Results from these experiments suggest that adolescents exhibit impaired learning, behavioral inhibition and self-control, and in concert with recent reports, provide researchers with three behavioral models to more fully explore neurobiology of risk-taking behavior in adolescence. (PsycINFO Database Record (c) 2011 APA, all rights reserved)     

Trigeminal denervation and operant behavior in the rat.

39 male Wistar rats underwent selective sectioning of trigeminal sensory and motor nerves in 2 experiments to examine the contribution of the sensorimotor system to the control of instrumental responses reinforced with food or water. It was hypothesized that trigeminal denervation would disrupt motivational systems mediating Ss' thirst and hunger. Results show that unilateral sectioning of either Section V sensory or V motor nerves had no significant effect on leverpressing. Bilateral sectioning significantly reduced leverpressing, and the deficit was greatest in Ss with trigeminal motor nerve sectioning. It is concluded that trigeminal orosensory or oromotor denervation disrupts performance on a food- or water-reinforced task in which execution does not require a trigeminally mediated response. Findings are discussed in terms of motivational and reinforcement accounts of instrumental learning. (32 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Effects of operant level, interview with experimenter, and awareness upon verbal conditioning of chronic schizophrenics.

The present research attempted to (a) cross-validate N. D. Vestre's (1961, 1965) findings that medium-operant-level pronouns can be conditioned by "good" in a chronic schizophrenic population, (b) test whether or not high-operant-level pronouns can be conditioned by "good" in a chronic schizophrenic population, and (c) compare the conditionability of high-operant-level with that of medium-operant-level pronouns. It was hypothesized that schizophrenics would be more conditionable following a brief, friendly, personal interview than in the absence of any preconditioning interview. It was expected that awareness of the response-reinforcement contingency would favor conditioning. Both the operant level and interview with experimenter variables were investigated to see whether or not either differentially affected (a) the number of aware Ss and (b) the performance of aware Ss. "Good" functioned as a reinforcer for about 1/4 of the Ss in this study. The most important factor contributing to performance was awareness of the response-reinforcement contingency. Also, reinforcement tended to be more effective when Ss had no (instead of a S-min) preexperimental interview with E. Medium-operant-level pronouns were conditionable, and results of conditionability comparisons between high- and medium-preference pronouns depended upon how performance was measured. The negligible conditionability of high-preference pronouns was discussed. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Primacy of interresponse-time reinforcement in accounting for rate differences under variable-ratio and variable-interval schedules.

Pigeons' keypeck rates under VR schedules are typically higher than under VI schedules when between-schedule reinforcement rates are equated. Exp I, with 4 male White Carneaux pigeons, reproduced this between-schedule rate difference in a multiple VR-VI schedule. However, when the short interresponse times (IRTs) typically reinforced under VRs were required for VI reinforcement, between-component rate differences diminished. Exp II (4 Ss) replicated Exp I except that long IRTs reinforced under VI schedules were required for VR reinforcement. This manipulation eliminated between-schedule rate differences. In Exp III (4 Ss), VR/VI and VI/VR tandems had the same correlation between response and reinforcement rates. In a simulation, C. P. Shimp's (1969) IRT response rule was used as an algorithm to mimic between-schedule rate difference. Findings show that IRT reinforcement (a molecular factor), rather than the feedback function between response rate and reinforcement rate (a molar factor), accounts for the higher response rates under VR schedules. (25 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Exogenous hormones, reproductive history, and breast cancer

We studied 284 patients (20-74 years of age) with carcinoma of the breast and 367 controls; all were admitted to one hospital between 1969 and 1972. The disease was associated with nulliparity, first pregnancy over 20 years of age, premenopausal status, and a lower frequency of artificial menopause. After adjustment for these factors, no significant difference was found between the breast cancer patients and controls in their prior use of either estrogens or oral contraceptives, but the confidence limits on the relative risk, especially for oral contraceptives, were large.     

Hypothalamic self-stimulation and operant activity in the mottled mutant mouse

Cell-mediated immunity to bacterial antigens was studied by intradermal testing, and to contact antigens (cosmetics, environmental chemicals and topical medicaments) by patch testing in 270 children with atopic dermatitis. The incidence of delayed-type immune cutaneous reactions in these patients was lower than in the controls. Contact allergy is a rare finding in the first 4 years of life but its incidence increases subsequently. In subjects with atopic dermatitis the incidence of sensitization by contact with allergens contained in topical medicaments proved to be lower than in subjects with eczema of other types. The data collected points to a reduced cell-mediated immune reactivity in a proportion of subjects with atopic dermatitis.