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Biomedical subjects

W Theodore

Publications and source records attributed to W Theodore.

13 recordsLinked to original sources
PubMed2004

Calcific neurocysticercosis and epileptogenesis.

Neurocysticercosis is responsible for increased rates of seizures and epilepsy in endemic regions. The most common form of the disease, chronic calcific neurocysticercosis, is the end result of the host's inflammatory response to the larval cysticercus of Taenia solium. There is increasing evidence indicating that calcific cysticercosis is not clinically inactive but a cause of seizures or focal symptoms in this population. Perilesional edema is at times also present around implicated calcified foci. A better understanding of the natural history, frequency, epidemiology, and pathophysiology of calcific cysticercosis and associated disease manifestations is needed to define its importance, treatment, and prevention.

Animals↗
PubMed2001

Conjoint and extended neural networks for the computation of speech codes: the neural basis of selective impairment in reading words and pseudowords.

The computation of speech codes (i.e. phonology) is an important aspect of word reading. Understanding the neural systems and mech- anisms underlying phonological processes provides a foundation for the investigation of language in the brain. We used high-resolution three-dimensional positron emission tomography (PET) to investigate neural systems essential for phonological processes. The burden of neural activities on the computation of speech codes was maximized by three rhyming tasks (rhyming words, pseudowords and words printed in mixed letter cases). Brain activation patterns associated with these tasks were compared with those of two baseline tasks involving visual feature detection. Results suggest strong left lateralized epicenters of neural activity in rhyming irrespective of gender. Word rhyming activated the same brain regions engaged in pseudoword rhyming, suggesting conjoint neural networks for phonological processing of words and pseudowords. However, pseudoword rhyming induced the largest change in cerebral blood flow and activated more voxels in the left posterior prefrontal regions and the left inferior occipital-temporal junction. In addition, pseudoword rhyming activated the left supramarginal gyrus, which was not apparent in word rhyming. These results suggest that rhyming pseudowords requires active participation of extended neural systems and networks not observed for rhyming words. The implications of the results on theories and models of visual word reading and on selective reading dysfunctions after brain lesions are discussed.

Adult↗
PubMed2001

Aggression and psychiatric comorbidity in children with hypothalamic hamartomas and their unaffected siblings.

OBJECTIVE: To assess aggression and psychiatric comorbidity in a sample of children with hypothalamic hamartomas and gelastic seizures and to assess psychiatric diagnoses in siblings of study subjects. METHOD: Children with a clinical history of gelastic seizures and hypothalamic hamartomas (n = 12; age range 3-14 years) had diagnoses confirmed by video-EEG and head magnetic resonance imaging. Structured interviews were administered, including the Diagnostic Interview for Children and Adolescents-Revised Parent Form (DICA-R-P), the Test of Broad Cognitive Abilities, and the Vitiello Aggression Scale. Parents were interviewed with the DICA-R-P about each subject and a sibling closest in age without seizures and hypothalamic hamartomas. Patients were seen from 1998 to 2000. RESULTS: Children with gelastic seizures and hypothalamic hamartomas displayed a statistically significant increase in comorbid psychiatric conditions, including oppositional defiant disorder (83.3%) and attention-deficit/hyperactivity disorder (75%). They also exhibited high rates of conduct disorder (33.3%), speech retardation/learning impairment (33.3%), and anxiety and mood disorders (16.7%). Significant rates of aggression were noted, with 58% of the seizure patients meeting criteria for the affective subtype of aggression and 30.5% having the predatory aggression subtype. Affective aggression was significantly more common (p < .05). Unaffected siblings demonstrated low rates of psychiatric pathology on semistructured parental interview and no aggression as measured by the Vitiello Aggression Scale. CONCLUSIONS: Children with hypothalamic hamartomas and gelastic seizures had high rates of psychiatric comorbidity and aggression. Parents reported that healthy siblings had very low rates of psychiatric pathology and aggression.

Adolescent↗
PubMed2000

Lack of effect of St John's Wort on carbamazepine pharmacokinetics in healthy volunteers.

BACKGROUND: St John's Wort is a popular herbal product used by approximately 7% of patients with epilepsy. Previous reports have described reductions in concentrations of CYP3A4 substrates indinavir and cyclosporine (INN, ciclosporin) associated with St John's Wort. OBJECTIVE: Our objective was to determine the effect of St John's Wort on steady state carbamazepine and carbamazepine-10,11-epoxide pharmacokinetics. METHODS AND SUBJECTS: Eight healthy volunteers (5 men; age range, 24-43 years) participated in this unblinded study. Subjects received 100 mg of carbamazepine twice daily for 3 days, 200 mg twice daily for 3 days, and then 400 mg once daily for 14 days. Blood samples were collected before and 1, 2, 4, 6, 8, 10, 12, and 24 hours after the dose on day 21. The subjects then took 300 mg of St John's Wort (0.3% hypericin standardized tablet) 3 times daily with meals and with carbamazepine for 14 days. On day 35, blood sampling was repeated. Plasma samples were analyzed for carbamazepine and carbamazepine-10,11-epoxide with HPLC. We compared carbamazepine and carbamazepine-10,11-epoxide noncompartmental pharmacokinetic parameter values before and after St John's Wort with a paired Student t test. RESULTS: We found no significant differences before or after the administration of St John's Wort in carbamazepine peak concentration (7.2 +/- 1 mg/L before versus 7.6 +/- 1.3 mg/L after), trough concentration (4.8 +/- 0.5 mg/L before versus 4.3 +/- 0.8 mg/L after), area under the plasma concentration-time curve (142.4 +/- 12.9 mg x h/L before versus 143.8 +/- 27.2 mg x h/L after), or oral clearance (2.8 +/- 0.3 L/h before versus 2.9 +/- 0.6 L/h after). Similarly, no differences were found in peak concentration (2 +/- 0.5 mg/L before versus 2.1 +/- 0.4 mg/L after), trough concentration (1.3 +/- 0.3 mg/L before versus 1.4 +/- 0.3 mg/L after), and area under the plasma concentration-time curve (37.5 +/- 7.4 mg x h/L before versus 41.9 +/- 10.3 mg x h/L after) of carbamazepine-10,11-epoxide. CONCLUSIONS: The results suggest that treatment with St John's Wort for 14 days did not further induce the clearance of carbamazepine.

Adult↗
PubMed1999

Epilepsy in Latin America and the Caribbean: a survey on needs and resources.

A survey was done on the needs and resources available to control epilepsy in the countries of Latin America and the Caribbean. Responses came from ministries of health, prominent neurologists, and epilepsy advocacy organizations. A mailed questionnaire was used, and the response rate was excellent, 89%. The survey results showed that the private sector is better equipped to deal with epilepsy than is the public sector, in terms of both specialized personnel and access to a variety of drugs. Public policies are lacking, and linkages between medical personnel and social workers are almost nonexistent. Primary care doctors and nurses are somewhat able to diagnose some types of epilepsy but do less well with other types of the disorder. There is a strong justification for the new "Out of the Shadows" initiative, in which the International League Against Epilepsy, the International Bureau for Epilepsy, the World Health Organization, and the Pan American Health Organization are working to improve epilepsy health-care services, treatment, and social acceptance.

Caribbean Region↗
PubMed1990

Depression, anxiety, and temporal lobe epilepsy. Laterality of focus and symptoms.

The association between anxiety, depression, and lateralization of an epileptogenic focus was explored in 18 adult patients with a left temporal lobe focus, 21 with a right focus, 20 with bilateral temporal foci, and 16 individuals with absence seizures. No significant difference in the level of anxiety was found among the groups. However, patients with left-sided temporal lobe epilepsy scored significantly higher than other groups on self-ratings for depression. This could not be accounted for by factors such as duration of epilepsy, employment status, education, age at seizure onset, or medication status. The left temporal lobe epilepsy group had a nonsignificantly larger number of males and left-handed subjects. The possible interactions between gender, handedness, seizure focus, and vulnerability to depression are described.

Adult↗
PubMed1987

Effect of barbiturate coma on glucose utilization in normal brain versus gliomas. Positron emission tomography studies.

Glucose utilization by normal and neoplastic cerebral tissue can be measured in humans using positron emission tomography (PET) with fluorine-18-labeled 2-deoxy-D-glucose (FDG). Malignant gliomas are known to exhibit hypermetabolic glucose consumption compared to normal brain. Barbiturate-sensitive cerebral glucose utilization is coupled to neuronal activity, and lesions lacking neuronal activity should be relatively insensitive to barbiturate suppression of glucose utilization. In a study to examine this phenomenon, three patients with cerebral gliomas underwent FDG-PET while awake and during deep barbiturate coma. Cerebral glucose utilization was measured in normal brain, tumor, and a homologous, non-neoplastic control site in the contralateral hemisphere. A glucose utilization ratio for tumor/control tissue was calculated. The mean reduction of glucose utilization during barbiturate coma was: gray matter 67%, white matter 47%, basal ganglia 66%, thalamus 57%, cerebellar cortex 55%, tumor 32%, and the contralateral control site 64%. The mean tumor glucose utilization ratio was 1.48:1 in the awake state and 2.69:1 during barbiturate coma. The changes in gray matter, basal ganglia, thalamus, cerebellar cortex, and tumor/control tissue ratio were significant (p less than 0.05). In one patient, deep tumor invasion not evident on computerized tomography, magnetic resonance imaging, or baseline FDG-PET was apparent during barbiturate-enhanced FDG-PET scanning. The study findings suggest that gliomas resist suppression of glucose utilization by barbiturates; this supports the hypothesis that barbiturates reduce neuronal metabolism by blocking synaptic activity. This differential effect on normal brain and gliomas enhances the capability to assess the extent of neoplastic tissue in brain and may represent the basis for novel therapeutic strategies.

Adult↗
PubMed1985

Transient sensory, cognitive and affective phenomena in affective illness. A comparison with complex partial epilepsy.

Behavioural changes have often been noted in patients with epilepsy. This study investigated the converse phenomenon--the occurrence of transient sensory, cognitive and affective changes resembling those described by epileptics, in affectively ill patients. Forty-four patients with affective illness, 37 with complex partial seizures, and 30 hypertensive controls were interviewed to determine the lifetime occurrence of these phenomena. Such symptoms occurred frequently in association with episodes of affective illness and epilepsy, but were rare in controls. Visual, auditory, olfactory and epigastric symptoms, illusions, jumbled thoughts and amnesia were common to both epilepsy and affective illness. Greater numbers of symptoms were associated with better response to lithium and tricyclic antidepressants. Transient sensory, cognitive, and affective phenomena may be more common in affective illness and other psychiatric conditions than is generally recognised, and may be clues to the underlying pathophysiology of these conditions.

Adult↗
PubMed1981

Mechanism of valproate-phenobarbital interaction in epileptic patients.

Valproate effects on phenobarbital biodisposition were examined in a search for the mechanisms of the valproate-induced elevation of plasma phenobarbital during antiepileptic therapy. The study involved patients who were treated with phenobarbital alone and phenobarbital plus valproate. Several kinetic parameters were determined after a pulse dose of stable isotope-labeled phenobarbital, with plasma phenobarbital levels at a steady state. Plasma elimination of labeled phenobarbital was studied by selected ion monitoring. The addition of valproate to the phenobarbital regimen resulted in elevation of plasma phenobarbital and increase in urinary output of unchanged phenobarbital. There was no effect on urinary pH. The rise in plasma phenobarbital was paralleled by lengthening of phenobarbital elimination half-life while the decrease of plasma phenobarbital clearance paralleled the decrease in phenobarbital elimination rate constant. These findings suggest that inhibition of phenobarbital metabolism by valproate is the mechanism for this clinically important drug-drug interaction.

Adolescent↗