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Biomedical subjects

P Martin

Publications and source records attributed to P Martin.

At least 757 records · Page 42Linked to original sources
PubMed1988

[Multicenter survey related to the frequency of positive patch tests with mercury and thiomersal].

A multicentric study concerning the frequency of positive allergic patch test reactions to mercury and to thiomersal has been conducted in France and in Belgium among 2,000 adult patients submitted to routine patch testing. 73 (3.6 p. 100) patients had a positive patch test to mercury and 47 (2.3 p. 100) to thiomersal, 22 (1.1 p. 100) reacted positively to both mercurials. These high figures are most probably in relation with a broad use of mercurials in both countries, as antiseptics as well as preservative agents in topical drugs. They lead to a careful use of mercurials, which have to be avoided when they can be advantageously replaced by other antiseptics or preservative agents. As far as cosmetics are concerned, the use of mercurials (chemical nature and concentration) is restricted by a Recommendation of the European Council.

Adult↗
PubMed1987

Delayed behavioral response to antidepressant drugs following selective damage to the hippocampal noradrenergic innervation in rats.

The present study was undertaken to investigate in rats the role of the noradrenergic innervation of the hippocampus in the reversal by antidepressant drugs of escape failures caused by previous exposure to inescapable shocks (learned helplessness design). Rats were either sham-operated or given a bilateral infusion of 6-hydroxydopamine (6-OHDA, 8.1 micrograms of free base in 0.8 microliter saline containing 0.02% ascorbic acid) into the dorsal hippocampus. Three weeks later, sham and lesioned rats were exposed (experimental rats) or not exposed (control rats) to 60 randomized, inescapable footshocks (0.8 mA, 15 s duration) and, 48 h later, experimental and control rats were subjected to daily consecutive shuttle-box sessions (30 trials/day; intertrial interval = 30 s). Separate groups of experimental animals were given twice daily injection (i.p.) of clomipramine (total daily dose: 16 or 32 mg/kg), desipramine (24 mg/kg), imipramine (32 mg/kg), nialamide (16 mg/kg) or saline. After behavioral testing, animals were sacrificed and [3H]noradrenaline uptake was assayed in synaptosomal preparations from the hippocampus, the cerebral cortex and the septum, [3H]serotonin uptake being assessed in hippocampal synaptosomes. We found that hippocampal 6-OHDA infusion resulted in a mean 70% reduction in local [3H]noradrenaline uptake and a marked delay in the response to antidepressants (reversal of escape failures over consecutive shuttle-box sessions). The 6-OHDA infusion was found not to alter hippocampal [3H]serotonin uptake but to decrease (30%) [3H]noradrenaline uptake in the cerebral cortex.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1987

Passive smoking.

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Humans↗
PubMed1987

Passive smoking.

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Child↗
PubMed1987

Triiodothyroacetic acid-induced reversal of learned helplessness in rats.

Triiodothyronine (T3), successfully used as therapeutic agent in euthyroid depressive states, has been found to exert an antidepressant-like effect in various psychopharmacological tests in rodents. Therefore the possible antidepressant-like activity of triiodothyroacetic acid (TA3), a natural metabolite of T3, was investigated in rats subjected to helplessness training. The animals were first exposed to inescapable shock pretreatment (60 shocks, 15 s duration, 0.8 mA every min +/- 15 s) and 48 h later, shuttle-box training (30 trials/day, ITI: 30 s) was performed on 3 consecutive days in order to assess escape deficits. As compared to control rats (no shock pretreatment), the rats exposed to inescapable shocks exhibited escape deficits when tested for subsequent responding in the shuttle-box. Daily i.p. injections of TA3 (0.5 mg/kg) prevented escape deficits as did daily injections of tricyclic antidepressants. These data are in agreement with previous results bearing on the similarity of action of TA3 and tricyclic antidepressants and extend to the thyroid axis the neuroendocrine systems that can be affected by exposure to uncontrollable stressors.

Animals↗
PubMed1987

Passive smoking.

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Humans↗
PubMed1987

Isotretinoin-associated proctosigmoiditis.

A 17-yr-old boy developed acute proctosigmoiditis after the institution of isotretinoin for the treatment of cystic acne vulgaris. Painless diarrhea, accompanied by mucus and eventually blood, began within days of commencing treatment and persisted while the drug was administered. At sigmoidoscopy patchy mucosal inflammation associated with numerous discrete aphthous ulcers was seen, apparently restricted to the rectosigmoid. Histologic examination of the affected mucosa revealed an acute focal superficial inflammatory infiltrate. Withdrawal of the drug resulted in prompt resolution of symptoms and a reduction in the severity of the inflammation. Rechallenge with isotretinoin induced a second, almost identical, attack of proctosigmoiditis. Withdrawal was again followed by disappearance of symptoms, and a subsequent sigmoidoscopy and mucosal biopsy were normal. The patient has remained clinically well for 16 mo after his initial presentation. Although the pathogenesis of the colonic mucosal inflammation remains unknown, the relationship of the bouts of proctosigmoiditis to the administration of isotretinoin strongly suggests that the drug was directly responsible.

Adolescent↗
PubMed1987

"Crack" (an extra potent form of cocaine) abuse: a problem of the eighties.

"Crack," an extra potent form of purified cocaine, is being abused today across the United States. The drug is no longer confined to the inner city. Its presence is ubiquitous in the middle class. "Crack" users can become dangerous to themselves and to others, even to the extent of committing murder. Cardiac irritability and hypertension are among the associated severe problems of "crack" abuse. The toxicity of cocaine is therefore a major problem. It is imperative that all practitioners become aware of the signs and symptoms of cocaine toxicity and its management. This awareness can help to avoid or alleviate a crisis in the clinic or office.

Central Nervous System↗
PubMed1987

Noradrenergic rather than GABAergic processes as the common mediation of the antidepressant profile of GABA agonists and imipramine-like drugs in animals.

The present study was aimed at investigating in rats whether a common mechanism might underlie the reversal of depressive-like behaviors by classical antidepressants and by GABA agonists such as muscimol. Blockade of GABA transmission with picrotoxin (1 mg/kg IP) abolished the muscimol (0.5-1 mg/kg)-induced reduction of immobility in the swimming test and the reversal of escape failures in the learned helplessness paradigm. Conversely, picrotoxin was found not to reduce the efficacy of imipramine-like drugs in these same animal models. The combination of muscimol and tricyclics given at subeffective doses resulted in behavioral changes that can be accounted for by an additive interaction between these two classes of drugs. These data confirm the antidepressant-like profile of GABA agonists but suggest that it is unlikely that the primary antidepressant mechanism of conventional antidepressants involves GABA-A receptors. In the swimming test, prazosin (2 mg/kg), an alpha adrenoceptor blocker, antagonized the reduction of immobility produced by both muscimol and imipramine-like drugs. In the learned helplessness paradigm, penbutolol (0.25-0.5 mg/kg) and, though to a lesser extent prazosin, counter-acted the reversal of escape failures caused by muscimol and imipramine. On the basis of these data, it is tempting to speculate that increased transmitter outflow at noradrenergic receptors may be an essential component in the mechanism of action of imipramine-like drugs but also of GABA agonists.

Animals↗
PubMed1987

Behavioral effects of THC as a function of environment and prior drug experience.

Holtzman albino rats were divided into 4 groups, and on 5 consecutive days each group was exposed to one of 4 conditions. The drug-adapted group was given delta-9-tetrahydrocannabinol (THC) (0.0, 0.5, 2.5 or 5.0 mg/kg PO) in their home cages, while the environment-adapted group was given vehicle and placed for one hr in the chamber where they were later tested. The naive group was given vehicle in their home cages and the drug + environment adapted group was given THC and placed in the test chamber. One week later, all rats were given either 0.0, 0.5, 2.5, or 5.0 mg/kg THC and placed in the test chamber where standing, sitting, and behavioral activity were measured. The results showed that the behavioral effects of THC are a function of environmental familiarity in rats who are drug naive but not in rats given prior exposure to THC.

Adaptation, Psychological↗
PubMed1987

Triiodothyronine potentiation of antidepressant-induced reversal of learned helplessness in rats.

Several clinical investigations have suggested that a special relationship exists between thyroid function and affective disorders and/or therapeutic response to antidepressants. The present report describes that the reversal by antidepressants (imipramine, desipramine, and nomifensine) of depressive-like behavior in rats (escape deficits produced by previous exposure to uncontrollable stress) was significantly hastened in animals given daily triiodothyronine (T3). The learned helplessness paradigm might be a useful model for approaching in animals the neurohormonal correlates of affective disorders and the neurobiochemical bases of the reported T3 enhancement of antidepressants.

Animals↗