Biomedical subjects

E Mervaala

Publications and source records attributed to E Mervaala.

79 records · Page 5Linked to original sources

PubMedDate not supplied

Visual evoked potentials, brainstem auditory evoked potentials, and quantitative EEG in Baltic progressive myoclonus epilepsy.

Visual and brainstem auditory evoked potentials (VEP and BAEP, respectively) and quantitative EEG were studied in 16 patients with Baltic progressive myoclonus epilepsy (PME). The study demonstrated significantly delayed VEP latencies but normal amplitudes in Baltic PME. BAEPs showed slight but significant prolongation in central conduction time. Quantitative EEG revealed diminution of beta and alpha activity and accentuation of theta and delta activity. The slowing in VEP latencies is suggested to be due to impaired synaptic transmission and to reflect dopaminergic dysfunction in Baltic PME. We conclude that there is a multimodal disturbance in sensory projections to cortical areas in Baltic PME. The results give further evidence that nondemyelinating disorders--but with synaptic transmission defects--can produce changes in evoked potentials. The changes in epileptic brain are not confined to hyperexcitable epileptic neurons, but more widespread electrophysiological phenomena are produced.

Adolescent↗

PubMedDate not supplied

Electrophysiologic effects of gamma-vinyl GABA and carbamazepine.

The effects of gamma-vinyl GABA (GVG) and carbamazepine (CBZ) monotherapy on somatosensory (SEP) and visual (VEP) evoked potentials and spectral quantitative EEG (QEEG) were studied in 17 patients with complex partial seizures using a cross-over double-blind study design. CBZ was associated with statistically significant prolongation of SEP latencies. When the drug was switched to GVG, shortening of the peak latencies was observed. Prolonged pattern-VEP peaks were observed both during CBZ and GVG monotherapies. A similar but more subtle tendency of the peaks was observed in P100 latencies. Spectral EEG revealed a slowing of the occipital rhythm with CBZ. No QEEG changes related to GVG were found. The use of multimodal evoked potentials and QEEG should be considered in studying the effects of new antiepileptic drugs (AEDs).

Adult↗

PubMedDate not supplied

Pre- and postoperative auditory event-related potentials in temporal lobe epilepsy.

We studied auditory event-related potentials (ERPs) in 11 surgically treated patients with intractable temporal lobe epilepsy (TLE) pre- and postoperatively. ERPs through sphenoidal electrodes (Sp1-T3, Sp2-T4) provided clinically relevant and correctly lateralizing electrophysiologic evidence of temporal lobe dysfunction in 9 of 11 patients, confirmed by EEGs, electrocorticograms, neuroradiologic, and neuropsychological results, and clinical follow-up. Lateralizing asymmetries were noted in P300 amplitude, but latencies were prolonged bilaterally. Sphenoidal ERPs might serve as a new functional indicator of temporal lobe dysfunction in patients evaluated for epilepsy surgery.

Adolescent↗

PubMedDate not supplied

Gamma-vinyl GABA (vigabatrin) in epilepsy: clinical, neurochemical, and neurophysiologic monitoring in epileptic patients.

We report long-term clinical, neurochemical, and electrophysiologic data of gamma-vinyl GABA (GVG, vigabatrin) in three groups of patients. GVG was started as add-on therapy for 75 patients with refractory complex partial seizures (group A) and for 36 mentally handicapped patients with severe epilepsy (group B). The third group (C) consisted of 20 patients with carbamazepine (CBZ) monotherapy, in half of whom GVG monotherapy was substituted. After 3 months, 55% of patients in group A and 42% in group B were responders (reduction in seizure frequency greater than 50%). After 6 (group A) and 3 years (group B) of follow-up, 27 and 33% of the patients, respectively, still had good response to GVG. Neurochemical measurements showed a twofold increase in CSF GABA concentrations and minimal or no changes in other neurotransmitter-related parameters. In group C, substitution of GVG as medication tended to normalize the lengthened latencies in somatosensory evoked potentials (SEPs) observed during CBZ treatment.

Adult↗

PubMedDate not supplied

Postoperative EEG and electrocorticography: relation to clinical outcome in patients with temporal lobe surgery.

To evaluate the role of different EEG methods with respect to postoperative clinical follow-up, 32 non-lesionary epilepsy patients who had undergone temporal lobectomy were studied preoperatively and at 2-week, 3-month, and 1-year postoperative follow-up. Routine, sleep, and sphenoidal EEG recordings as well as intraoperative electrocorticography (ECoG) were made for all patients. At 1-year follow-up, the EEGs with sphenoidal electrodes and with sleep deprivation procedure provided important prognostic information; the appearance of seizures was associated with the presence of interictal epileptiform abnormalities in EEG. In the postresection ECoG, however, epileptiform abnormalities were not associated with clinical outcome or with postoperative epileptiform EEG at 1 year. Routine EEG reliably reflects clinical outcome after temporal lobectomy; with sphenoidal electrodes as well as with sleep deprivation procedure, the diagnostic yield can be further improved.

Adolescent↗

PubMedDate not supplied

Clinically important factors influencing endothelial function.

The endothelium, a continuous cellular monolayer lining the blood vessels, has an enormous range of important homeostatic roles. It serves and participates in highly active metabolic and regulatory functions including control of primary hemostasis, blood coagulation and fibrinolysis, platelet and leukocyte interactions with the vessel wall, interaction with lipoprotein metabolism, presentation of histocompatibility antigens, regulation of vascular tone and growth and further of blood pressure. Many crucial vasoactive endogenous compounds like prostacyclin, thromboxane, nitric oxide, endothelin, angiotensin, endothelium derived hyperpolarizing factor, free radicals and bradykinin are formed in the endothelial cells to control the functions of vascular smooth muscle cells and of circulating blood cells. These versatile and complex systems and cellular interactions are extremely vulnerable. The balances may be disturbed by numerous endogenous and exogenous factors including psychological and physical stress, disease states characterized by vasospasm, inflammation, leukocyte and platelet adhesion and aggregation, thrombosis, abnormal vascular proliferation, atherosclerosis and hypertension. The endothelial cells are also the site of action of many drugs and exogenous toxic substances (e.g. smoking, alcohol). As markers and assays for endothelial dysfunction, direct measurement of nitric oxide, its metabolites from plasma and urine, functional measurement of vascular nitric oxide dependent responses and assay of different circulating markers have been used. In numerous pathological conditions (e.g. atherosclerosis, hypertension, congestive heart failure, hyperhomocysteinemia, diabetes, renal failure, transplantation, liver cirrhosis) endothelial dysfunction has been described to exist. Some of them, as well as hormonal and nutritional factors and drug treatment will be discussed in this short review.

Aging↗

PubMedDate not supplied

Indapamide treatment modifies the vascular reactivity of normotensive rat mesenteric arteries ex vivo.

Indapamide is an antihypertensive diuretic drug of which the precise antihypertensive mechanism has not been clarified. The aim of the present study was to investigate with mesenteric arteries of normotensive rats the possible change in vascular reactivity ex vivo and in vitro after indapamide application, taking into special consideration the role of endothelium. After seven days of drug treatment in vivo with low-dose 0.3 mg/kg/day or high-dose 3 mg/kg/day of indapamide the effect on the vascular responses ex vivo were compared to controls. The contractions induced by noradrenaline (NA) or potassium chloride (KCl) were increased in vascular rings without endothelium in the high-dose indapamide group. No alterations in endothelium-dependent relaxation responses to acetylcholine (ACh) or endothelium-independent responses to sodium nitroprusside (SNP) were found between any of the treatment groups in vascular rings with or without endothelium. When indapamide (1 microM or 10 microM) was added in vitro for 10 min preincubation it did not significantly change the vascular contractions induced by cumulatively increased concentrations of NA or KCl. The relaxation responses induced by ACh or SNP were also not affected by indapamide pretreatment. Our results suggest that the lack of change in contractile response in vitro after indapamide pretreatment might be related to the prodrug nature of indapamide, which is not metabolized during the short preincubation.

Animals↗