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Biomedical subjects

P Simon

Publications and source records attributed to P Simon.

At least 415 records · Page 23Linked to original sources
PubMed1985

[Statistical study of a series of 355 subtalar fractures of the calcaneus. Therapeutic conclusions].

A retrospective study has been made of 355 fractures of the os calcis involving the subtalar joint in order to determine the best method of treatment. A rating system was used to assess the different types of injury. The results were correlated with the pattern of depression of the posterior articular surface, the quality of restoration of this surface and the type of trauma. We conclude that Duparc Stage V fractures require reconstruction/arthrodesis (the Stulz proceedure). Duparc Stage I fractures, and Stage III or IV with grade I depression, should be treated conservatively with early mobilisation. Stage III or IV fractures with grade II or III depression require operation in order to restore and maintain a congruent posterior joint surface to allow early mobilisation.

Accidents, Occupational↗
PubMed1985

Metabolism and pharmacokinetics of vinyl acetate.

The hydrolysis of vinyl acetate (formation of acetic acid) has been studied in vitro with rat liver and lung microsomes, rat and human plasma and purified esterases (such as acetylcholine esterase, butyrylcholine esterase, carboxyl esterase). Characterization of the kinetic parameters revealed that rat liver microsomes and purified carboxyl esterase (from porcine liver) displayed the highest activity. In order to establish the rate of metabolism of vinyl acetate in vivo, rats were exposed in closed desiccator jar chambers, and gas uptake kinetics were studied. The decay of vinyl acetate was dose-dependent, indicating possible saturation of metabolic pathway(s). The maximal clearance (at lower concentrations) of vinyl acetate from the system (30 000 ml/h per kg body weight) was similar to the maximal ventilation rate in this species. This indicated that under conditions when metabolic enzymes are not saturated the metabolic rate is mainly determined by pulmonary uptake. The exposure of rats to vinyl acetate resulted in a transient exhalation of significant amounts of acetaldehyde into to the closed exposure system. This indicates the presence of this metabolic intermediate of vinyl acetate in the organism in vivo.

Animals↗
PubMed1985

The tail suspension test: a new method for screening antidepressants in mice.

A novel test procedure for antidepressants was designed in which a mouse is suspended by the tail from a lever, the movements of the animal being recorded. The total duration of the test (6 min) can be divided into periods of agitation and immobility. Several psychotropic drugs were studied: amphetamine, amitriptyline, atropine, desipramine, mianserin, nomifensine and viloxazine. Antidepressant drugs decrease the duration of immobility, as do psychostimulants and atropine. If coupled with measurement of locomotor activity in different conditions, the test can separate the locomotor stimulant doses from antidepressant doses. Diazepam increases the duration of immobility. The main advantages of this procedure are the use of a simple, objective test situation, the concordance of the results with the validated "behavioral despair" test from Porsolt and the sensitivity to a wide range of drug doses.

Animals↗
PubMed1985

Benzodiazepines reduce the tolerance to reward delay in rats.

This study investigated whether benzodiazepines reduce the capacity of animals to wait for food reward. Rats trained in a T-maze were allowed to choose between two magnitudes of reward: immediate, but small (two pellets) vs delayed, but large (eight pellets). The rats learned within ten sessions to select (80-100%) the arm leading to the largest reward. Separate groups of rats were then confined for 15, 30 or 60 s in the arm associated with the largest reward before gaining access to the spacially contiguous goal-box. The choice of the other arm was not followed by a period of waiting. Under these conditions, the frequency with which the small-reward arm was chosen increased linearly as a function of the duration of the waiting period. Diazepam (2-4 mg/kg IP) dose-dependently increased the number of times the small-reward arm was chosen during the sessions for which the waiting period was fixed at 15 or 30 s. Nitrazepam (2 mg/kg IP), chlordiazepoxide (16 mg/kg IP) and clobazam (16 mg/kg IP) had similar effects. The action of diazepam was counteracted by simultaneous administration of flumazepil (Ro 15-1788, 8 mg/kg PO). In the absence of confinement, these benzodiazepines, diazepam (4 mg/kg) excepted, did not modify selection of the large-reward arm. Conversely, the serotonin uptake blockers indalpine (2-4 mg/kg IP) and zimelidine (8-16 mg/kg IP) dose-dependently increased preference for the arm leading to the delayed (25 s) but large reward. These results suggest that benzodiazepines, perhaps by increasing impulsivity, render the animals less prone than controls to tolerate delayed access to reward.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1985

Is delay of reward mediated by shock-avoidance behavior a critical target for anti-punishment effects of diazepam in rats?

The present study investigated in rats whether variables which may affect the animals' tolerance for delay of reward could be critical for the benzodiazepine-induced release of punished behavior. Rats were subjected to conflict situations during which signalled FR4 non-punished periods (lights-off) alternated with punished periods of different durations signalled by lights-on stimuli. Lever presses during punished periods resulted in the delivery of both one food-pellet and one electric foot-shock (0.45 mA). The antipunishment effect of diazepam (2 mg/kg IP) clearly depended on the duration of the punished periods, release of punished behavior being observed only when punished periods exceeded 1 min. The duration of punished periods required for diazepam-induced release of responding was affected by factors which modified the contrast between rewards received in punished and non-punished periods. One of these factors was the FR schedule imposed during non-punished periods, since the anti-punishment effect of diazepam was observed during short-lasting (30-s and 1-min) punished periods separated by FR24 non-punished periods. A second factor was the ratio of the durations of punished and non-punished periods: diazepam released behavior during 2-min punished periods when the duration of the intercurrent non-punished periods was 1 min, but not when it was 4 min. The predictability of the duration of the punished periods also modulated the effect of diazepam since: with 1 min punished periods, diazepam released punished responding during the first exposures of the rats to the experimental session, but lost part or all its efficacy in animals extensively trained to the procedure.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1985

Tolerance to or facilitation of pharmacological effects induced by chronic treatment with the beta-adrenergic stimulant clenbuterol.

The effect in mice of chronic administration of the beta-adrenergic agonist clenbuterol was studied using four pharmacological tests, two of which are predictive of antidepressant activity in man. The suppressive effect of acute administration of the beta-adrenergic agonist in two tests unrelated to antidepressant activity, locomotor activity and investigation of food, was attenuated after chronic treatment. However, in the two tests which are predictive of antidepressant activity, antagonism of reserpine induced hypothermia and potentiation of yohimbine toxicity, the effect of clenbuterol was greater following chronic treatment.

Animals↗
PubMed1985

Effect of brain-stem lesion on colonic and anorectal motility. Study of three patients.

The supraspinal control of colonic motility and anorectal motility is poorly documented. We had the opportunity to study colonic function, esophageal function, and urinary bladder function in three patients who presented with vascular lesions limited to the anterior (case 1) or the posterior area (cases 2 and 3) of the pons. Esophageal manometry, urodynamic examination, whole and segmental transit time measurements (using radiopaque markers) and anorectal motility were systematically performed. The results were the following: (1) in the first case esophageal motility was not altered, whereas abnormal micturition, right colonic inertia, and absence of rectoanal inhibitor reflex were observed; (2) in cases 2 and 3, there was a poor esophageal coordination, the micturition and rectoanal inhibitor reflex were normal, and the transit time of the left colon was increased. Our observations are consistent with the previously described localization of neurological areas controlling swallowing and micturition; they also favor the pons as the possible level of supraspinal control of colonic and anorectal motility.

Adult↗
PubMed1985

Comparison of imipramine-imipraminium in mice. To elucidate central or peripheral origin of effects of imipramine.

Imipramine hydrochloride shows effects in a battery of tests used for the screening of antidepressant drugs. The central origin of these pharmacological effects of imipramine has not been clearly established. Imipramine methiodide is a quaternary derivative of imipramine which does not cross the blood-brain barrier easily. The effects of the two forms of imipramine have been compared: on an effect known to have a central origin; on two effects known to have a peripheral origin; on a battery of tests used for the screening of antidepressant drugs. It has been demonstrated that imipramine methiodide is as active as imipramine hydrochloride on two effects of peripheral origin, less active than imipramine hydrochloride on an effect considered to have a central origin and less active than imipramine hydrochloride or inactive on the tests which are used for the screening of antidepressant drugs. Consequently, the tests used for the screening of antidepressant drugs represent, primarily or exclusively, effects of central origin.

Animals↗
PubMed1985

Dissociation of head twitches and tremors during the study of interactions with 5-hydroxytryptophan in mice.

Intraperitoneal injection of 5-hydroxytryptophan and 5-methoxy-N,N-dimethyltryptamine is shown to provoke characteristic behaviors in mice that can be quantified. The two principal phenomena described here are head twitches and tremors. Tremors became more frequent when doses of the two substances studied were increased. Head twitches appeared at lower doses, but beyond a certain dose, they decreased and even disappeared. The effects on these movements of agents that modify serotonin function were then studied. The results pose problems of interpretation that are discussed.

Animals↗
PubMed1985

Vinyl acetate: DNA-binding assay in vivo.

The question of carcinogenicity of vinyl acetate led us to perform a DNA binding assay in vivo in rats, using 14C-labelled vinyl acetate. After administration of [14C]vinyl acetate to male and female Fischer-344 rats, either orally or by inhalation, no specific hepatic DNA adducts, known to occur after administration of labelled vinyl halides or vinyl carbamates, could be detected in hepatic tissues.

Animals↗
PubMed1985

Detoxification in hemosiderosis.

Transfusional iron overload in patients with chronic renal failure is a growing concern and its therapeutic approach develops both on the lines of prevention and of cure. It is now proved that the control mechanisms which relate iron absorption to body iron stores are intact in patients on dialysis. Oral iron therapy is therefore recommended in almost all patients. In some dialysis patients with transfusion-dependent anemia, a measure currently acknowledged to reduce transfusion iron overload consists of the use of young instead of mature erythrocytes for transfusions. The tissue depletion of iron by desferrioxamine is an alternative therapy which can prevent hemosiderosis or cure organ dysfunction due to iron overload. In some patients, the simultaneous occurrence of iron and aluminum overload suggests there may be competition between chelation of iron and aluminum. In fact, clinical studies show that both iron and aluminum can be removed by administration of desferrioxamine.

Administration, Oral↗
PubMed1985

[The development of legal premises in the rehabilitation of the physically handicapped from Bismarck to today--a brief overview].

The legal bases for rehabilitation and integration of the physically disabled have developed from public welfare provisions, the beginnings of disability care having been part of public poor relief schemes. Ensueing developments range from cripple care programmes to today's efforts to establish a uniform social code, which is expected to benefit the individual disabled person by bringing about a marked simplification of the current legal and administrative situation. The extension of the scope of rehabilitative efforts, which since Bismarck's time had comprised nursing and institutional care in cases of physical and mental ailings within the framework of poor relief, had initially occurred outside Prussia by including education and vocational training for disabled people (the beginnings of "rehabilitation"). A more comprehensive approach to disability care in the sense of extended assistance was embodied in the Prussian cripple welfare act of 1920. The Federal Social Assistance Act of 1962, in the final analysis, had developed from this tradition. This 1962 act not only established a duty to provide public welfare but also gave those concerned a legal title to this kind of assistance.

Persons with Disabilities↗
PubMed1985

[The scimitar sign: a pulmonary vein or systemic artery? Apropos of a case of pure vascular sequestration].

The scimitar sign, characterised by a vertical opacity crossing the medial part of the right diaphragm, is generally attributed to abnormal pulmonary venous return draining into the inferior vena cava. This is not the only situation in which the scimitar sign is observed, which can also be seen in association with systemic anomalies, in particular sequestration. The authors report the case of a young adult in whom the chest x-ray presented the scimitar sign from childhood. This image was related to a pure pulmonary vessel sequestration by a right sub-phrenic artery. The authors stress the possibility of a purely arterial origin for the scimitar sign in the absence of any abnormality of pulmonary venous return.

Adolescent↗
PubMed1985

[Complications and results of Wertheim's operation performed for the treatment of uterine cancer].

Enlarged colpohysterectomy with lymphadenectomy was performed in 199 patients for cancer of cervix (132 cases), of endometrium (67 cases), of vagina (2 cases) or of tubes (1 case) during combined radiosurgical therapy of these tumors. There was no mortality, the incidence of thrombo-embolic accidents was 3% and urinary fistula was not seen. A lumphocele developed in 7.5% of cases, this level being related to the degree of lymphatic curettage, which should involve not less than 13 glands to avoid lack of efficacy and not more than 20 glands to prevent complications, in cervical cancer. For endometrial cancer, curettage is limited to external iliac obturator glands and retrocrural nodes in young women, and is even omitted in elderly women.

Adolescent↗