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Biomedical subjects

L Gjerstad

Publications and source records attributed to L Gjerstad.

28 records · Page 2Linked to original sources
PubMed1981

Monosynaptic transmission during epileptiform activity induced by penicillin in hippocampal slices in vitro.

Synaptic transmission was studied in the CA1 region of transverse hippocampal slices in vitro before and after the addition of the epileptogenic agent sodium benzyl penicillin. The presynaptic fibre volley and the field potential associated with the intracellular EPSP, 'field EPSP', were recorded from the layer of the activated synapses. Addition of penicillin did not change either response. The rising phase of the intracellularly recorded EPSP did not change. However, the peak amplitude and, particularly, the duration of the EPSP both increased. The prolongation of the EPSP may be of importance for the triggering of epileptiform bursts.

Evoked Potentials↗
PubMedDate not supplied

A new injectable carbamazepine solution--antiepileptic effects and pharmaceutical properties.

Carbamazepine (CBZ) could be dissolved in Glycofurol (polyethylene glycol monotetra-hydrofurfuryl ether) with concentrations up to 100 mg/ml, and the solutions were stable for at least 14 days. Ethanol or benzyl alcohol was added without loss in solubility, while water, human serum albumin or Intralipid always led to immediate precipitation. The effect of a CBZ/Glycofurol solution on focal seizure threshold in the visual cortex in cats was investigated using a cerveau isolé preparation. Fourteen experiments were performed using i.v. injections of CBZ with concentrations ranging from 0.2 to 20 mg/kg. In all experiments with doses greater than 1 mg/kg the CBZ/Glycofurol injections exerted a pronounced and immediate effect on the seizure threshold, while Glycofurol alone was ineffective. On average, seizure threshold increased more than 5-fold with doses in the range of 5-20 mg/kg. Investigating the effect of CBZ/Glycofurol on picrotoxin-induced seizure activity in cats, 2 injections of 5 mg/ml of CBZ immediately stopped the seizure activity as evaluated by electrocorticography, while interictal activity remained.

Animals↗
PubMedDate not supplied

Association between regularly occurring complex partial seizures and thyroid function parameters.

A 28-year-old man with regularly occurring clusters of complex partial seizures was studied over a total of 224 days. His seizure periods lasted 2-4 days and occurred at intervals of 5-6 weeks. Several parameters were studied. The most striking finding was an increase in the serum concentration of thyroxine prior to and during the seizure periods. The concentrations of urine catecholamines and serum cortisol also varied with the seizure periods, but these hormones increased after the seizure periods had begun. To determine if there is a general 4-6-week rhythm in thyroid hormone concentrations, 12 weekly blood samples from 10 healthy male students were analyzed. No rhythmicity was found.

Adult↗
PubMedDate not supplied

Triiodothyronine and brain excitability.

We investigated mechanisms involved in thyroid hormone action on brain excitability. The effect of acute exposure of triiodothyronine (T3) to rat hippocampal slices in vitro was studied. No significant changes could be detected in prevolley, field excitatory postsynaptic potentials (fEPSP) and population spike amplitude, while there was a minor, nonsignificant trend toward shortening of the population spike latency time. T3 had no effect on penicillin-induced epileptiform activity. There was, however, an active accumulation of radioactively labeled T3 in the slices. A rat cervaux-isolé preparation was used to determine focal seizure thresholds in the visual cortex, and no acute (2-4 h) effects were demonstrated. No significant acute effects of T3 on brain excitability in the hippocampus and visual cortex was observed, despite an active accumulation of T3. Thus, the effect of T3 on brain excitability most likely is due to delayed effects.

Animals↗
PubMedDate not supplied

Cognitive function and time-of-day variation in serum carbamazepine concentration in epileptic patients treated with monotherapy.

Different parameters of antiepileptic drug (AED) treatment have been shown to affect cognitive function. The drug, dose, and duration of treatment have been studied. The present study assessed cognitive function in relation to time-of-day variation in serum carbamazepine (CBZ) concentration in epileptic patients treated with monotherapy. We studied 10 males and 12 females with a mean age of 36 years and a mean duration of CBZ-therapy of 4.4 years. Patients had been seizure-free for at least 1 month and took two daily CBZ doses. The test battery included tests of motor speed, reaction time, attention, and memory. In the experimental design, the subjects were tested twice at times close to expected daily maximum and minimum serum CBZ concentration. They were studied in two balanced blocks (block 1 tested at 8 a.m. and noon, block 2 tested at noon and 8 p.m.). Blood samples were collected every 2 hr from 8 a.m. to 8 p.m. The subjects showed significant differences in serum CBZ concentration between testing times, with suggested maximum concentration between 10 a.m. and noon. The test battery showed no consistent differences between performance at times of high versus low serum concentration. A supplementary analysis of correlations between mean performance level on cognitive tests and variables related to CBZ treatment did not show consistent trends.

Adolescent↗