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PubMed1978

[Vitaminology for practitioners. II. Avitaminoses, risk, latency period, classification].

The concept of risk in the field of avitaminoses is very important and useful for the practitioner, who should consider two aspects: a) risk factors, which could be individual (physiological, pathological and psychological) and extra-individual (alimentary, environmental, etc.); b) subjects with an elevated risk of avitaminosis (childhood, old age, pregnancy, etc.). In these subjects the risk can be a generical one, when there is an elevated requirement for all vitamins (nursing women, sportmen, etc.) or a specific one, when there is a high requirement only for a single vitamin (osteomalacia, some professional diseases, use of oral contraceptives) or a vew of them (alcoholism, diabetes, etc.). On the basis of this kind of knowledge it is easy for the practitioner to estimate which vitamins are necessary for each subject or for a group of subjects in physiological or in pathological conditions. For example, there is an elevated risk of apyridoxinosis in old age (acalciferolosis in aged women), of athiaminosis and apyridoxinosis in diabetes, of apyridoxinosis in oral contraceptives users, of axeroftolosis in hyperthyroidism, of athiaminosis, apyridoxinosis, aniacinosis and anascorbosis in alcoholics. In the second chapter the concept of the latency period in avitaminosis is illustrated. This period corresponds to the interval between the moment when deficiency stimulus starts operating and the moment when its effect, that is the picture of avitaminosis, appears. The latency time is not measurable, on account of the difficulties in establishing the onset of the deficiency stimulus; generally it is very long and is followed by the period of biochemical symptomatology and subsequently by the one of clinical symptomatology. Each of these three phases can be further divided in several steps, which have summarized in a Table. The last chapter is dedicated to the classification of avitaminoses. From the etiopathogenetic point of view avitaminoses can be due to: a) deficiency of introduction (alimentary level)); b) deficiency of absorption (enteric level); c) deficiency of utilization (tissue level). From the clinical point of view avitaminoses can be distinguished in deficiency with: a) a complete clinical symptomatology (scurvy, beriberi, pellagra, rickets, osteomalacia, xerophthalmia, hemeralopia); b) an incomplete clinical symptomatology (mono- or oligo-symptomatic or partial clinical picture); c) a biochemical symptomatology only (subclinic or clinically asymptomatic picture).

Age Factors↗
PubMed1994

Identification of hair cell progenitors and intermitotic migration of their nuclei in the normal and regenerating avian inner ear.

Postembryonic production of sensory hair cells occurs in both normal and aminoglycoside-damaged avian inner ears. The cellular source and mechanism that results in new differentiated hair cells were investigated in the avian vestibular epithelia using three distinct cell-cycle-specific labeling methods to identify proliferating sensory epithelial cells. First, immunocytochemical detection of the proliferating cell nuclear antigen, an auxiliary protein of DNA polymerase, allowed labeling of cells in late G1, S, and early G2 phases of the cell cycle. Second, a pulse-fix tritiated thymidine autoradiographic protocol was used to identify cells in S phase of the cell cycle. Finally, Hoechst 33342, a fluorescent DNA stain, was used to identify epithelial cells in mitosis. The distribution of cells active in the cell cycle within the normal and ototoxin-damaged vestibular epithelium suggests that supporting cells within the sensory epithelia are the cellular precursors to the regenerated hair cells. Differences between the proliferation marker densities in control and damaged end organs indicate that the upregulation of mitotic activity observed after streptomycin treatment is due primarily to an increase in the number of dividing progenitor cells. The differences between the extent of ototoxic damage and the level of reparative proliferative response suggest a generalized stimulus, such as a soluble chemical factor, plays a role in initiating regeneration. Finally, after DNA replication is initiated, progenitor cell nuclei migrate from their original location close to the basement membrane to the lumenal surface, where cell division occurs. This pattern of intermitotic nuclear migration is analogous to that observed in the developing inner ear and neural epithelium.

Aminoglycosides↗
PubMed1976

Length of residence, social ties, and economic opportunities,.

This study examines length of residence for movers--that subsection of the population which accounts for the high mobility rates in the United States. The propensity for repeated migration is studied in relation to economic opportunities and previous familial and personal contacts. The results indicate no influence of economic opportunities on duration of residence. This finding is consistent with recent research that indicates economic conditions are not a general stimulus for out-migration, although they are for inmigration. On the other hand, length of residence is found to be longer where previous familial and personal contacts existed. Overall, the results provide additional evidence of the importance of social, as opposed to strictly economic variables in the migration process.

Family↗
PubMed1993

Generalization of a tactile stimulus in horses.

Using horses, we investigated the control of operant behavior by a tactile stimulus (the training stimulus) and the generalization of behavior to six other similar test stimuli. In a stall, the experimenters mounted a response panel in the doorway. Located on this panel were a response lever and a grain dispenser. The experimenters secured a tactile-stimulus belt to the horse's back. The stimulus belt was constructed by mounting seven solenoids along a piece of burlap in a manner that allowed each to provide the delivery of a tactile stimulus, a repetitive light tapping, at different locations (spaced 10.0 cm apart) along the horse's back. Two preliminary steps were necessary before generalization testing: training a measurable response (lip pressing) and training on several reinforcement schedules in the presence of a training stimulus (tapping by one of the solenoids). We then gave each horse two generalization test sessions. Results indicated that the horses' behavior was effectively controlled by the training stimulus. Horses made the greatest number of responses to the training stimulus, and the tendency to respond to the other test stimuli diminished as the stimuli became farther away from the training stimulus. These findings are discussed in the context of behavioral principles and their relevance to the training of horses.

Animals↗
PubMed1984

Effects of the training dose on generalization of morphine stimulus to clonidine.

The relationship between the stimulus properties of morphine and clonidine was tested in rats trained to discriminate morphine sulfate (4, 2 or 1 mg/kg) from saline in a two-lever food-rewarded task. The response trained in the low dose group generalized to low doses of clonidine (0.125 to 0.5 mg/kg) whereas the response trained with the high dose of morphine generalized only to higher doses of clonidine (0.625 to 1.0 mg/kg). Naloxone blocked the generalization in the low dose group but only partially blocked it in the high dose group. Yohimbine blocked the generalization to clonidine in the high morphine dose group and reversed the response rate suppressant effect of clonidine in all groups.

Animals↗
PubMed2004

Semantic generalization of stimulus-task bindings.

People find it difficult to switch between two tasks, even if they have time to prepare-the so-called residual task shift cost. We studied a switch of tasks from picture naming to word reading, using picture-word Stroop stimuli. Consistent with previous findings, we demonstrate that a large part of the observed task shift cost was due to priming from prior stimulus-response episodes, in which the current task stimulus was encountered in a competing task. We further show that this task-priming effect generalizes to semantically related stimuli, which opens the possibility that most or all of these residual shift costs reflect some sort of generalized proactive interference from previous stimulus-task episodes.

Adult↗
PubMed1989

Training and generalization of agrammatic aphasic adults' wh-interrogative productions.

The stimulus and response generalization effects of training wh-interrogative production were examined in 4 agrammatic Broca's aphasic subjects using a multiple baseline design across behaviors and subjects. Throughout treatment, response generalization to untrained questions and stimulus generalization to several nontraining conditions were assessed. Variable response generalization to untrained exemplars of trained wh-interrogative forms and little generalization to grammatically different wh constructions occurred. Stimulus generalization to only one of three conditions was noted. However, generalization treatment involving sequential modification of training across conditions was found to be effective in facilitating generalization to an additional stimulus condition for 2 of the 4 subjects.

Aged↗
PubMed1995

The effects of chronic morphine on the generalization of buprenorphine stimulus control: an assessment of kappa antagonist activity.

Rats trained to discriminate the mixed mu agonist/kappa antagonist buprenorphine from its vehicle generalize buprenorphine control to morphine. Buprenorphine, however, does not generalize to MR2266. The generalization to morphine suggests that buprenorphine's mu agonist properties mediated in part its discriminative control. The failure to generalize to MR2266, a compound reported to block kappa-mediated effects, however, suggests that its kappa antagonist activity was not involved in its discriminative effects. The ability of buprenorphine's mu (but not kappa) activity to establish stimulus control may be a function of the overshadowing of the kappa properties of buprenorphine by its concurrent mu activity. To test this possibility, in the present experiment rats were chronically exposed to morphine prior to buprenorphine discrimination training. This procedure has been reported to result in tolerance to buprenorphine's mu agonist effects and a more pronounced display of its kappa antagonist properties. The rats were then tested for the generalization of buprenorphine control to morphine, MR2266, and pentobarbital. As expected, buprenorphine failed to generalize to the nonopioid pentobarbital. Although subjects were tolerant to morphine (as evidenced by reductions in morphine-induced behavioral effects and a rightward shift in the doses of morphine substituting for buprenorphine), buprenorphine still failed to generalize to MR2266. The failure of buprenorphine to generalize to MR2266 under conditions that should have allowed for the development of stimulus control by buprenorphine's kappa antagonist activity was discussed in terms of the general inability of kappa antagonist activity to support discrimination learning.

Animals↗
PubMed2005

Effects of morphine on temporal discrimination and color matching: general disruption of stimulus control or selective effects on timing?

Discrepant effects of drugs on behavior maintained by temporal-discrimination procedures make conclusive statements about the neuropharmacological bases of timing difficult. The current experiment examined the possible contribution of a general, drug-induced disruption of stimulus control. Four pigeons responded on a three-component multiple schedule that included a fixed-interval 2-min, temporal discrimination, and color-matching component. Under control conditions, response rates and choice responses during the first two components showed evidence of control by time, and accuracy for color matching was high in the third component. Morphine administration flattened the distribution of fixed-interval responding and produced a general disruption of accuracy in the temporal-discrimination component, whereas accuracy in the color-matching component was relatively unaffected. Analysis of the psychophysical functions from the temporal-discrimination component indicated that morphine decreased accuracy of temporal discrimination by decreasing overall stimulus control, rather than by selectively affecting timing. These results suggest the importance of determining the neurophysiological bases of stimulus control as it relates to temporal discrimination.

Animals↗
PubMed1987

Surgical audit in a district general hospital: a stimulus for improving patient care.

A computerised audit system was used to monitor clinical and administrative management of surgical patients in a District General Hospital. In one year (1985) there were 1,060 discharges from 27 beds (39.3 patients/bed/year). Operative treatment was required in 652 patients but 408 patients did not undergo surgery. Of this latter group the majority were admitted with abdominal pain (179 patients) and a final diagnosis was made in only 76 patients. The majority of patients were discharged within one week of admission, but 94 patients (8.9%) were admitted for more than three weeks. Of this group 42.5% could not be discharged because of poor home and social circumstances. The results of this study suggest that management could be improved without compromising patient care, in particular by providing adequate facilities for day care surgery and by improving social and geriatric support services. Reductions in staff or bed numbers without providing such improvements will lead to a significant reduction in patient care.

Adult↗
PubMed1985

Heart-rate responses of infant rats and guinea pigs to stimulus onset and offset: tests of the generality of a bidirectional effect.

To test the generality, across modality and across species, of a bidirectional effect of photic stimulation in infant rats found in previous experiments, two experiments examined the effects on heart rate (HR) of onset and offset of auditory stimulation in rats and of photic stimulation in guinea pigs. Experiment 1 demonstrated a unidirectional, decelerative response in rats 17 and 21 days of age to the onset and offset of a 1-kHz tone, at both low (80 dB) and high (100 dB) intensity levels and at 14 days to the onset of the high-intensity tone. Experiment 2 demonstrated that infant guinea pigs, which unlike infant rats are precocial and not nocturnal, responded to the offset but not to the onset of light, and that this response was decelerative. These results indicated a lack of generality of the bidirectional HR effect, and were discussed in terms of the orienting/defensive reflex distinction.

Acoustic Stimulation↗
PubMed1999

Cocaine-seeking produced by experimenter-administered drug injections: dose-effect relationships in rats.

RATIONALE: Relapse to drug taking is a major obstacle to the effective treatment of cocaine abuse. Animal studies have determined that various drugs are able to reinstate extinguished drug-taking behavior. OBJECTIVES: This study was designed to determine whether there is specificity in the ability of drugs to lead to cocaine-seeking and to compare potency and efficacy of a variety of drug primes. Another objective was to compare the effect of drugs with a primary dopaminergic mechanism with those having a secondary effect on dopaminergic substrates. METHODS: Following acquisition of cocaine self-administration, the ability of injections of cocaine (5.0-20.0 mg/kg), amphetamine (0.30-3.0 mg/kg), methylphenidate (2.0-20.0 mg/kg), nicotine (0.0375-0.60 mg/kg), caffeine (1.25-20.0 mg/kg), morphine (0.10-10.0 mg/kg) or delta 9THC (0.3-3.0 mg/kg) to reinstate extinguished drug taking was measured. Tests were conducted in a single day and were comprised of three phases. The first phase consisted of a 60-min period of cocaine self-administration. During phase 2, the cocaine solution was replaced with saline and responding was extinguished during the next 3-h period. During phase 3, in which saline again was the only solution available for self-administration, responding was monitored for 3-8 h following an injection of a drug prime. RESULTS: Reinstatement was produced by experimenter-administered injections of cocaine, amphetamine, methylphenidate and caffeine but not nicotine, morphine or delta 9THC. The potency and efficacy of cocaine, methylphenidate and caffeine were comparable, whereas amphetamine was more potent and efficacious. Cocaine seeking occurred primarily during the first hour following the injection. CONCLUSIONS: These findings suggest that cocaine seeking is only produced following administration of specific drugs. It is suggested that effective drug primes are those that produce a discriminative stimulus that generalizes to the stimulus produced by the reinforcing effects of cocaine.

Animals↗