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Biomedical subjects

P Mares

Publications and source records attributed to P Mares.

At least 253 records · Page 14Linked to original sources
PubMed1988

Epileptic phenomena produced by kainic acid in laboratory rats during ontogenesis.

Because of its preferential neuroexcitatory effects on the hippocampal neurones kainic acid (KA) is used for inducing partial seizures with a complex symptomatology. In this study the authors investigated the effect of intraperitoneal administration of KA, in doses of 2-16 mg/kg, on the laboratory rat during ontogenesis. The experimental animals were males aged 7, 12, 18, 25 and 90 days. The first signs of an effect in adult rats were automatisms; in young animals, jerks also appeared. The most important automatisms were wet dog shakes, which preponderated in 25-day-old and older animals, whereas in the young rats they consisted chiefly of intensive scratching. Minimal seizures with a motor pattern identical to minimal metrazol seizures were observed in all the age groups and so were generalized tonic-clonic convulsions, which appeared after large doses of KA. The systemic administration of KA is a convenient model of temporal seizures and their progressive generalization and could act as a model for testing broad spectrum antiepileptics.

Age Factors↗
PubMed1988

Rapid pre-operative immunotherapy in a patient allergic to muscle relaxants.

Allergic reactions to muscle relaxants are not uncommon. Although, in most instances, divalent quaternary ammonium salts are involved in these reactions, some monovalent quaternary ammonium compounds can trigger IgE-mediated reactions. A woman who suffered from several episodes of anaphylaxis with divalent (suxamethonium) and monovalent quaternary ammonium salts (tiemonium) needed surgery. Regional anaesthesia was contra-indicated owing to a possible intolerance to local anaesthetics. Investigation confirmed an allergy to monovalent quaternary ammonium salts. Rapid immunotherapy was started with a monovalent quaternary ammonium salt (tiemonium) and subsequently followed by a general anaesthesia using vecuronium. The patient did not develop anaphylactic symptoms.

Adult↗
PubMed1988

Ontogenetic development of etomidate action in rats.

Action of etomidate was studied in 219 albino rats 7, 12, 18, 25 days old and adult. Etomidate at the dose of 20 mg/kg i.p. led to a loss of the righting reflex in all age groups. Sleeping time increased with decreasing age up to the 12th day. Seven-day-old rat pups exhibited short sleeping time, approximately at the level of adult animals. Etomidate can be used for general anaesthesia even in young animals but the quantitative differences in its efficacy have to be taken into account.

Analysis of Variance↗
PubMed1987

Ontogenetic development of convulsant action of Ro 5-3663 in the rat.

Motor seizures were induced by Ro 5-3663 in 156 male albino rats aged 7,12,18,25, and 90 days. Both minimal and maximal seizures could be elicited in 18-day-old and older animals, whereas only maximal seizures were induced in the two youngest groups. ECoG changes were studied in other 21 young rats. First changes induced by Ro 5-3663 were formed by isolated sharp waves in 7- and 12-day-old rats and by episodes of rhythmic activity in older animals. An imperfect form of this rhythmic activity could be seen even in 12-day-old rats. Ictal ECoG activity exhibited an increase in frequency of individual graphoelements, in generalization and in synchronization of activity among different cortical regions with maturation. Correlation between motor and ECoG phenomena was poor in 7-day-old rats and ameliorated with age but it never reached perfection. The actions of Ro 5-3663 are identical with those induced by metrazol but they differ from those elicited by bicuculline or 3-mercaptopropionic acid.

Animals↗
PubMed1987

Vanadate inhibition of rat cerebral cortex Na+,K+-ATPase during postnatal development.

The Na+,K+-ATPase activity and its response to vanadate inhibition was investigated in cerebral cortex homogenates of 7-, 12- and 18-day-old rats. The enzyme was inhibited by vanadate in a dose-dependent manner in all these age groups. Furthermore, there was a different sensitivity towards vanadate during postnatal development; the concentration of V+5 needed for 50% inhibition of Na+, K+-ATPase was 1.1 X 10(-6)M, 2 X 10(-7)M and 4.4 X 10(-7)M for 7-, 12- and 18-day-old rats, respectively. It is suggested that the different sensitivity of Na+, K+-ATPase towards vanadate inhibition during postnatal development might be due to age-dependent changes in the ratio of various cell types.

Aging↗
PubMed1987

Changes of activity of cortical neurons induced by acetylcholine in adult and young rats.

Acetylcholine was applied microiontophoretically by means of multibarrel electrodes to neurons in the sensorimotor cortex of adult, 18-, 15-, 12-, and 9-day-old rats anesthetized with urethane. A total of 229 neurons was recorded; only 22 of them were in 18- and 15-day-old rats because of similarity of results with those from adult as well as 12-day-old animals. In adult rats 43 of 58 neurons recorded in infragranular layers responded to acetylcholine with a marked increase in their firing. In 12-day-old rats the incidence of excitatory responses to acetylcholine was also high: 59 of 86 cells again were localized predominantly in deep cortical layers (V and VI). A marked difference was observed in 9-day-old rats: only 15 of 63 neurons were excited by acetylcholine. A majority of cells did not respond at all--including units localized in infragranular layers. Two cells in layer V responded to acetylcholine by an inhibition. Our results indicate that there is a marked increase in cholinoceptivity of cortical neurons between postnatal days 9 and 12. This finding is in agreement with the finding that local application of acetylcholine can elicit an epileptogenic focus in 12-day but not in 9-day-old rat pups.

Acetylcholine↗
PubMed1987

Effects of flunarizine on Metrazol-induced seizures in developing rats.

Antimetrazol action of flunarizine (5, 10, 20 and 40 mg/kg i.p.) was tested during ontogenesis on male Wistar rats aged 7, 12, 18, 25 and 90 days. The latencies and incidences of jerks, minimal Metrazol seizures and major Metrazol seizures remained unchanged by flunarizine in all age groups. A specific action (an abolition of the tonic phase of major seizures) was seen throughout the development and was reflected in lower scores of seizures.

Aging↗
PubMed1987

Electrocorticographic development of epileptogenic foci in the occipital region of the rat cerebral cortex.

The development of cortical penicillin foci in the occipital region was studied in rats whose ages ranged from five days up to the adult age. The local application of penicillin induced the formation of an epileptogenic focus for the first time at the age of seven days. With advancing age, the amplitude of focal discharges increased, the duration of the individual components of the discharge shortened, its originally negative-positive configuration changed to a triphasic form and in the third week of life initial positivity, for a time, become the dominant component of the discharge. Projection of the discharges to the contralateral hemisphere was found to be inconstant in the second postnatal week, but appeared regularly from the age of 14 days. Synchronization of the discharges of two symmetrical foci was very poor in 7-day-old young, but improved noticeably by the 14th day; it was never complete, however, even in adulthood. The activity of symmetrical foci changed spontaneously to ECoG seizures, which were most common in 7-day-old young (in which ictal activity was usually not generalized, however) and were least frequent in 14-day-old animals. Focal discharges could not be reliably triggered by electrical stimulation of the contralateral cortex until the age of 18 days and later. The occipital part of the cortex develops somewhat later than the sensorimotor, frontal region, and during its development there also appeared phenomena which are not present in the frontal cortex.

Aging↗
PubMed1987

Influence of clonazepam on cortical epileptogenic foci in the rat.

The antiepileptic action of clonazepam was studied on epileptogenic foci induced by penicillin in sensorimotor cortex in acute experiments in rats. Clonazepam (1 mg/kg intraperitoneally) only moderately decreased the frequency of interictal discharges of single cortical focus and delayed the propagation of discharges into the ipsilateral occipital region. On the contrary, clonazepam failed to influence the callosal projection of interictal discharges in single unilateral as well as in two symmetrical foci. Spontaneous transition of interictal discharges into ictal phases regularly seen when two symmetrical foci were formed was only delayed but not blocked by clonazepam. It may be concluded that clonazepam exhibits only a weak anticonvulsant action against cortical foci and against secondary generalization of epileptic activity.

Animals↗
PubMed1987

[Action of Parlodel on the preovulatory peak of estrogens and the ovulatory response of patients with abnormal ovulation and normal blood prolactin].

Bromocriptine, a dopamine agonist, is well known for its inhibitory action on prolactin secretion. Its action on other hypophyseal secretions, particularly on the gonadotrophins FSH and LH can indicate use of Parlodel as a stimulatory agent for induction of ovulation even in cases of normal prolactinemia. 129 normoprolactinemic patients with a defect of the preovulatory estrogen rise have been treated over a period of 3 months. 63% of the patients exhibited a positive response to bromocriptine, either because a pregnancy started or because preovulatory E1+E2 became normal. The rate of "responders" is increased among those patients who had conservation of spontaneous menses at the start of therapy. Conclusions of the study are that Parlodel has a place among treatments of ovulation defects. Its genuine efficacity must be confirmed by a controlled study against placebo and other confirmed treatments like antiestrogens.

Adolescent↗