Biomedical subjects

M J Morrell

Publications and source records attributed to M J Morrell.

5 recordsLinked to original sources

PubMed1992

Hormones and epilepsy through the lifetime.

Hormones influence brain function from gestation throughout life and may affect the seizure threshold by altering neuronal excitability. Estrogen enhances and progesterone diminishes neuronal excitability experimentally, whereas testosterone and corticosteroids have less consistent effects. Hormonal effects in the CNS also depend on the region of brain in which the hormone acts. Sites of action for most steroid hormones include the hypothalamus and limbic cortex, providing a mechanism for modulating behavior and endocrine function. Seizure patterns may change at certain life stages, perhaps as a result of alterations in hormones. At puberty, epilepsy and benign rolandic epilepsy often remit, while juvenile myoclonic and photosensitive epilepsy may arise. Other types of epilepsy do not respond predictably to events in the reproductive life or to advancing age. In some women, fluctuations in hormones over the menstrual cycle appear to increase seizure vulnerability, probably reflecting changes in relative amounts of estrogen and progesterone. Seizure patterns can be altered, for better or worse, during pregnancy. Whether this reflects the effects of hormones or changes in levels of antiepileptic drugs is not resolved. More information is needed about changes in established epilepsy at menopause and in the elderly. Better understanding of endocrine effects on seizures over a lifetime should lead to more effective epilepsy therapies.

Adolescent↗

PubMed1992

A noninvasive protocol for anterior temporal lobectomy.

We report the results of a protocol for choosing candidates for temporal lobectomy using a standard battery of objective tests without intracranial electrodes. We assigned each test a level of importance, and an algorithm was used to determine whether temporal lobectomy could be performed. Fifty-one patients (total pool, 103 patients) met protocol requirements and had an anterior temporal lobectomy with a mean follow-up of 39.4 months (range, 21 to 64 months), most remaining on anticonvulsant therapy. Eighty percent are seizure free, 12% have less than 3 seizures per year or only nocturnal seizures, and 8% have greater than 80% reduction in seizure frequency. One-third of patients who failed protocol criteria did not have temporal lobe seizures when studied with intracranial electrodes. We analyzed and modified the algorithm after comparing these patients with others who were poor candidates for temporal lobectomy. We conclude that this protocol is effective and recommend using such an objective algorithm.

Action Potentials↗

PubMed1991

Sexual dysfunction in epilepsy.

Sexual dysfunction may arise more frequently in men and women with epilepsy than with other chronic illnesses, manifesting primarily as diminished sexual desire and potency. Studies using retrospective self-report of sexual attitude and behavior find an incidence of sexual dysfunction ranging from 14-66%. Sexual dysfunction may be more common in partial than in generalized epilepsies. Sexual dysfunction in epilepsy may result from a disturbance in social or psychological factors affecting sexual responsiveness. Alternatively, epileptiform discharges may disrupt the function of structures mediating sexual behavior, particularly the limbic cortex, or alter the release of hypothalamic or pituitary hormones. Antiepileptic drugs modulate hormone release from the hypothalamic-pituitary-gonadal axis and may have direct inhibitory effects on sexual behavior. Evidence both supports and refutes each of these etiologies in the sexual dysfunction seen with epilepsy. Specific evaluation and treatment protocols for patients with sexual dysfunction are available.

Anticonvulsants↗

PubMedDate not supplied

Conversion of mannose to fructose by immobilized mannose isomerase from Pseudomonas cepacia.

The enzyme mannose isomerase (EC 5.3.1.7) catalyzes the isomerization of D-mannose and D-fructose. The conversion of mannose to fructose is the first step in the principal pathway of mannose dissimilation by Pseudomonas cepacia. This enzyme is induced during growth on medium containing mannose to levels three- to four-fold higher than observed during growth on glucose or citrate. Mannose isomerase was purified from extracts of mannose-grown P. cepacia and was efficiently immobilized onto a porous, noncompressible, ceramic support. The performance of the immobilized enzyme, compared with the soluble enzyme, was evaluated under a variety of operating conditions to examine its potential for use in a process for the production of fructose syrups containing a higher proportion of fructose than is currently possible using glucose isomerase.

Aldose-Ketose Isomerases↗

PubMedDate not supplied

Speech during partial seizures: intracranial EEG correlates.

Vocalization during a seizure may help predict the location of seizure onset or identify structures ultimately involved in the seizure. Spontaneous vocalization during seizures was studied retrospectively in 22 patients with refractory complex partial seizures evaluated with bilateral intracranial electrodes. Of 22 patients, 12 vocalized during seizures. Seizures were as likely to originate from language-dominant (6/12) as from language-nondominant mesial temporal cortex (6/12). Fluent speech frequently occurred as seizure activity was recorded from language-dominant temporal lobe neocortex (6/12 seizures). Of the patients with well-localized seizure onsets who did not speak (6/10), seizures arose from both language-dominant and -nondominant mesial temporal cortex. We conclude that the presence or absence of vocalizations during a seizure does not reliably indicate the anatomic regions in which the seizure begins or spreads.

Adult↗