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Biomedical subjects

C Vidal

Publications and source records attributed to C Vidal.

At least 127 records · Page 7Linked to original sources
PubMed1986

Phorbol ester-induced surface transferrin receptor modulation. No correlation with decreased cell proliferation.

Both phorbol ester or diacylglycerol (DAG) reduce cell surface transferrin receptor (TFR) number in CEM cells (a human T-cell acute lymphoblastic leukemia line) and HL-60 cells (a human promyelocytic leukemia cell line). This effect occurs with a t1/2 of approx. 30 min and is mimicked by addition of phospholipase C to cell cultures. Although cell surface TFR number is reduced to 25-30% of the control level 5 h after phorbol ester administration, apparent cell proliferation (as measured by [3H]thymidine incorporation) remains unaffected. Although independent of extracellular calcium (EGTA is slightly enhancing), the phenomenon is completely blocked by 30-min pretreatment with the calcium channel blocker diltiazem. Dilitazem pretreatment, while preventing receptor redistribution, does not completely block the phorbol ester-induced increase in TFR phosphorylation thought to be associated with receptor redistribution. Thus, calcium channel blockade effectively dissociates the effects of tetradecanoylphorbol acetate (TPA) on TFR internalization and phosphorylation. Our results also demonstrate that phorbol ester-induced effects on the TFR can be mimicked by the endogenous stimulator of protein kinase C, DAG, whether added directly to cultures or produced by the cells in response to exogenous phospholipase C. Furthermore, the phenomenon of TFR redistribution here described is not associated with a decreased proliferative capacity.

Cell Division↗
PubMed1986

[Tobacco detoxication by acupuncture and group psychotherapy].

In the out-patient tobacco detoxication unit created, in 1977, within the pneumology department of the Hôtel-Dieu hospital, Paris, the method used is a combination of acupuncture and group psychotherapy. Its effectiveness has been evaluated, over a 2-year period, by means of a questionnaire mailed to each patient and followed, if necessary, by up to 3 reminders. A computer-assisted assessment of the data thus collected provided a follow-up of varying duration of the 555 patients concerned; 488 patients were treated, then contacted, and 371 (76 p. 100) answered the questionnaire. Weaning--defined here as complete detoxication with a 2 to 28 months follow-up when the questionnaire was filled--was obtained in 24 p. 100 of the patients who answered. Other evaluation criteria would have given figures ranging from 18 p. 100 to 58.6 p. 100. The main reason for failure mentioned by the patients was lack of will. An exhaustive study of 84 publications concerning more than 10,000 candidates to weaning showed that similar results are obtained with several types of psychotherapy, acupuncture and auriculotherapy: a success rate of about 60 p. 100 at the end of treatment, 40 p. 100 at 3 months and 30 p. 100 at 6 months and one year. The results obtained with drugs are not as good, perhaps because their use betrays a lesser desire to give up smoking.

Acupuncture Therapy↗
PubMed1984

Regulation of body temperature and nociception induced by non-noxious stress in rat.

The effects of 3 different non-noxious stressors on body temperature (Tb) were investigated in the rat: (1) loose restraint in cylinders, (2) removal of the rats from cylinders, exposure to a novel environment and replacement in cylinders, a stressor called here 'novelty', and (3) gentle holding of the rats by the nape of the neck. Loose restraint and 'novelty' produced hyperthermia. On the contrary, holding induced hypothermia. Hypophysectomy (HX) reduced basal Tb, abolished restraint hyperthermia and reduced both 'novelty' hyperthermia and holding hypothermia. Dexamethasone ( DEXA ) had no effect upon either restraint or novelty hyperthermia but reduced the hypothermia. Naloxone (Nx) produced a slight fall in basal Tb accounting for its reduction of restraint and 'novelty' hyperthermias ; it did not affect holding hypothermia. The inhibitory effects of HX suggest a participation of the pituitary in the hyperthermias ; the neurointermediate lobe would be involved as the hyperthermias were not affected by DEXA , which is known to block the stress-induced release of pituitary secretions from the anterior lobe but not from the neurointermediate lobe. In contrast, substances from the anterior lobe might participate in hypothermia due to holding since it is reduced by HX and DEXA . As to the effects of Nx, endogenous opioids would not be significantly involved in the thermic effects of the stressors used in this study; they might play, if any, only a minor role in the regulation of basal Tb. These results are compared with those previously obtained on nociception using the same non-noxious stressors. It emerges that, depending on the stressor, different types of association between thermoregulation and nociception may occur, i.e. hyperthermia with analgesia, hyperthermia with hyperalgesia and hypothermia with hyperalgesia.

Animals↗
PubMed1984

Effects of dynorphin A (1-17), dynorphin A (1-13) and D-ala2-D-leu5-enkephalin on the excitability of pyramidal cells in CA1 and CA2 of the rat hippocampus in vitro.

The effects of D-ala2-D-leu5-enkephalin (DADL), dynorphin (DYN) A (1-17), and DYN A (1-13) on the excitability of hippocampal (HC) pyramidal cells in CA1 and CA2 were compared in an in vitro preparation of the rat. DADL and DYN A (1-13) increased the size of the population spike (PS) evoked in CA1 and CA2 by stimulation of the stratum radiatum. Paired-pulse stimulation showed that both peptides decreased the inhibition produced by the conditioning stimulus. These effects were naloxone-reversible. DYN A (1-17) decreased the PS in CA2 and increased the inhibition evoked by the conditioning stimulus. When applied in the same concentration-range, the depressant effects of DYN A (1-17) were more pronounced in CA1 than in CA2 and not naloxone-reversible. DYN A (1-17) reduced the excitatory effects of DADL. Low concentrations of DYN A (1-17) (0.1 nM) produced, like DYN A (1-13) and DADL, an increase in the PS in CA1 in the majority of tests. The present data suggest that DYN A (1-17) shows the excitatory action of other opioids HC pyramidal cells only at low concentration.

Animals↗
PubMed1984

[The development of human resources in the Americas. 1].

The first part of this paper (the second part will appear in the next issue) examines the development in the Region of manpower planning in the health field. Despite the progress made in manpower planning, training, development and utilization, especially under the stimulus of the drive to extend the coverage of health services, truly effective planning still faces major obstacles in the countries. The author describes the different kinds of personnel required for the health system and the problems created by a lack of connection between the needs of the population, economic and health policies, and the network for the training of that personnel. He finds that this lack of agreement stems from inadequate planning. Following a consideration of educational trends in Latin America, the author advocates the development of new approaches based on interdisciplinarity and leading to a greater integration of teaching and care as a means of optimal manpower planning in the health field.

Health Occupations↗
PubMed1984

[Development of human resources and the Plan of Action].

This article (whose first part was published in the previous issue of Educación Médica y Salud) concludes an exhaustive review of manpower development in the Americas. This part considers the specific measures in this field enunciated in the Plan of Action; these measures pertain to four main areas: planning and programming of human resources, training in priority areas, utilization of human resources, and educational technology. The author discusses the present and future possibilities and obstacles of each of these activities and the steps to be taken to bring needs into line with real situations. It is of paramount importance that the national health authorities clearly spell out their policies for the development of human resources in the health field within the framework of general development policies. Another point to be insisted upon is the multiprofessional and multidisciplinary training of the health team and the importance of the education-service-supervision function, which usually results in permanent and continuing education, which in turn optimizes the utilization of personnel. However, none of this will be possible without an appropriate education technology with which to innovate, analyze and refine the entire education process and so meet the needs of both society and the health services.

Health Education↗
PubMed1983

Hyper- and hypothermia induced by non-noxious stress: effects of naloxone, diazepam and gamma-acetylenic GABA.

Rats subjected to non-noxious, anxiogenic stressors were found to exhibit either hyperthermia or hypothermia depending on the nature of the stressor. The present work examines the effects of naloxone (Nx), diazepam (DZP) and gamma-acetylenic GABA (AcG), an inhibitor of GABA catabolism, on these phenomena. Nx reduced stress hyperthermia and basal temperature by similar amounts; it did not affect stress hypothermia. DZP also reduced basal Tb but was able to completely inhibit and even reverse stress hyperthermia and to reduce stress hypothermia. The effects of AcG were similar to those of DZP. In conclusion, it appears that endogenous opioids are not involved in the thermic responses to our emotional stressors whereas GABA would be an important modulator. It is suggested that DZP, through a GABAergic link might inhibit the release of hyperthermic pituitary factors from the neurointermediate lobe and of hypothermic substances from the anterior lobe.

4-Aminobutyrate Transaminase↗
PubMed1982

Hyperalgesia induced by non-noxious stress in the rat.

Stress-induced analgesia is well known but the reverse phenomenon is poorly documented. In this work, hyperalgesia is described following stressful but non-noxious manipulations consisting of inescapable holding or exposure to a novel environment. Hypophysectomy (HX) and dexamethasone enhanced 'holding' hyperalgesia. In contrast, 'novelty' hyperalgesia was reduced by HX and not modified by dexamethasone. So, pituitary factors may respectively compensate and take part in stress hyperalgesia. Thus pain can be modulated in opposite directions by different types of stimulation: hyperalgesia would predominate after moderate, anxiogenic stress and analgesia after noxious and/or intense stress.

Animals↗
PubMed1982

The effect of pituitary removal on pain regulation in the rat.

The effects of hypophysectomy (HX) on pain regulation in basal and in various stressful situations were investigated in the rat. Pain sensitivity was assessed by measuring the thresholds of 3 nociceptive reactions (tail withdrawal, vocalization, vocalization afterdischarge) following electrical stimulation of the tail. The completeness of HX and the integrity of hypothalamus were verified in each HX rat. (1) Baseline pain thresholds were lower in HX rats than in sham-operated animals; (2) naloxone (Nx) hyperalgesia was only slightly altered by HX; (3) different types of stress induced different types of changes in nociception i.e. analgesia or hyperalgesia. The influence of HX varied according to the stress: it increased hyperalgesia, reduced analgesia, or had no effect at all. These results indicate that in the rat: (i) the pituitary participates in the regulation of basal pain sensitivity, probably through analgesic factors; (ii) Nx hyperalgesia results essentially from an antagonism of endogenous opioids originating in the CNS and not in the pituitary; and (iii) the pain regulatory processes engaged in adaptation to stressful stimuli involve the CNS and the pituitary in variable proportions depending upon the nature of the stress.

Animals↗
PubMed1980

The effect of medial hypothalamus lesions on pain control.

In the rat, discrete electrolytic lesions located in 6 different parts of the medial hypothalamus (MH) are shown to induce clearcut hyperalgesia. During a time limit of 14 days following the lesions, no other obvious deficits were noticed (in sensory and/or motor functions, affectivity towards conspecifics, food and water intake). Three nociceptive reactions (tail withdrawal, vocalization, vocalization after-discharge) were tested and their thresholds measured following electrical stimulation of the tail. The lesions aimed at the rostral part of the arcuate nucleus, as well as at ventromedial and dorsomedial nuclei, produced the most profound hyperalgesia. The possible involvement of the endorphinergic and enkephalinergic systems known to be located in the MH is discussed. The relation between the hyperalgesic effects of MH lesions and various structures (limbic areas, descending pain control system, pituitary) is also considered.

Animals↗
PubMed1980

Periodic fluctuation in burst amplitude during 'fictive locomotion' in the cat.

In decorticated unanaesthetized and paralysed cats, locomotor bursting may develop spontaneously on hind-limb motor nerves. In defined experimental conditions, the amplitude of successive rhythmic bursts may fluctuate periodically as if a 'secondary oscillation' was superimposed upon the basic locomotor rhythm. The possible meaning of such amplitude fluctuation is discussed in connection with present data about the generation of locomotion.

Animals↗
PubMed1979

Central locomotor programming in the rabbit.

In decorticate, unanaesthetized and curarized rabbit preparations, with both hindlimbs deafferented, locomotor-like discharges were recorded from nerves to flexors and extensors and their time patterns were compared. The bursts of rhythmic activities recorded from nerves to several flexor muscles acting at either joint were shown to be synchronous, with no differences in their time of onset. The same was true for the extensors. Nerves to bifunctional muscles (biceps posterior, semi-tendinosus and tenuissimus) acting on two consecutive joints (knee flexors, hip extensors) could display two consecutive bursts in each locomotor cycle, one being pure flexor and the other an extensor discharge. It is shown here that this functional bivalence is programmed centrally and can be modulated, i.e. the relative importance of the flexor and the extensor bursts can be changed in a predictable way through afferent (proprioceptive or cutaneous) influences, or through activation of the descending monoaminergic pathways. In extreme cases, complete functional reversal was observed in these bifunctional muscle nerves.

Action Potentials↗