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Biomedical subjects

F Ritter

Publications and source records attributed to F Ritter.

At least 19 recordsLinked to original sources
PubMed2000

Intracranial EEG versus flumazenil and glucose PET in children with extratemporal lobe epilepsy.

OBJECTIVE: To compare abnormalities determined in 2-deoxy-2-[18F]fluoro-D-glucose (FDG) and [11C]flumazenil (FMZ) PET images with intracranial EEG data in patients with extratemporal lobe epilepsy. BACKGROUND: Although PET studies with FDG and FMZ are being used clinically to localize epileptogenic regions in patients with refractory epilepsy, the electrophysiologic significance of the identified PET abnormalities remains poorly understood. METHODS: We studied 10 patients, mostly children (4 boys, 6 girls, aged 2 to 19 years; mean age, 11 years), who underwent FDG and FMZ PET scans, intracranial EEG monitoring, and cortical resection for intractable epilepsy. EEG electrode positions relative to the brain surface were determined from MRI image volumes. Cortical areas of abnormal glucose metabolism or FMZ binding were determined objectively based on asymmetry measures derived from homotopic cortical areas at three asymmetry thresholds. PET data were then coregistered with the MRI and overlaid on the MRI surface. A receiver operating characteristics (ROC) analysis was performed to determine the specificity and sensitivity of PET-defined abnormalities against the gold standard of intracranial EEG data. RESULTS: FMZ PET detected at least part of the seizure onset zone in all subjects, whereas FDG PET failed to detect the seizure onset region in two of 10 patients. The area under the ROC curves was higher for FMZ than FDG PET for both seizure onset (p = 0.01) and frequent interictal spiking (p = 0.04). Both FMZ and FDG PET showed poor performance for detection of rapid seizure spread (area under the ROC curve not significantly different from 0.5). CONCLUSIONS: [11C]flumazenil (FMZ) PET is significantly more sensitive than 2-deoxy-2-[18F]fluoro-D-glucose (FDG) PET for the detection of cortical regions of seizure onset and frequent spiking in patients with extratemporal lobe epilepsy, whereas both FDG and FMZ PET show low sensitivity in the detection of cortical areas of rapid seizure spread. The application of PET, in particular FMZ PET, in guiding subdural electrode placement in refractory extratemporal lobe epilepsy will enhance coverage of the epileptogenic zone.

Adolescent↗
PubMed2000

Preconditioning prevents the inhibition of Na+,K+-ATPase activity after brain ischemia.

Application of single transient forebrain ischemia (ISC) in adult Wistar rats, lasting 2 or 10 min, caused inhibition of Na+,K+-ATPase activity in cytoplasmic membrane fractions of hippocampus and cerebral cortex immediately after the event. In the 2-min ISC group followed by 60 min of reperfusion, the enzyme inhibition was maintained in the cortex, while there was an increase in hippocampal enzyme activity; both effects were over 1 day after the event. However, in the 10-min ISC group enzyme inhibition had been maintained for 7 days in both cerebral structures. Interestingly, ischemic preconditioning (2-min plus 10-min ISC, with a 24-hour interval in between) prevented the inhibitory effect of ischemia/reperfusion on Na+,K+-ATPase activity observed either after a single insult of 2 min or 10 min ischemia. We suggest that the maintenance of Na+,K+-ATPase activity afforded by preconditioning be related to cellular neuroprotection.

Animals↗
PubMed2000

Attentional focus in complex skill learning.

Experiment 1 examined whether it is more advantageous to direct learners' attention to the external effects of their movements relative to other external cues. Two groups of participants hit tennis balls at a target, with one group focusing on the ball coming toward them (antecedent) and the other group focusing on the ball leaving the racket (effect). The effect group demonstrated more effective learning. Experiment 2 examined whether it is more beneficial if the movement effect is related to the movement technique, relative to other movement effects (e.g., outcome). Two groups of participants hit golf balls at a target. The attention of these groups was directed to the club or the ball trajectory, respectively. The club group showed more effective learning than the target group, suggesting that focusing on technique-related effects is more effective.

Adolescent↗
PubMed2000

Effectiveness, tolerability, and safety of topiramate in children with partial-onset seizures. Topiramate YP Study Group.

PURPOSE: Children with partial-onset seizures, with or without secondary generalization, participating in a double-blind, placebo-controlled trial of topiramate (TPM) as adjunctive therapy were eligible to participate in an open-label, long-term extension study. METHODS: A total of 83 children (mean age, 9 years) continued long-term open-label TPM therapy in which the dosages of TPM and concomitant antiepileptic drugs (AEDs) were adjusted according to clinical response (mean TPM dosage, 9 mg/kg/day). RESULTS: Seizure frequency over the last 3 months of therapy was reduced > or =50% in 57% of children; 14% of children were seizure-free > or =6 months at the last visit. During treatment periods up to 2 1/2 years (mean, 15 months), 6% of children discontinued because of treatment-emergent adverse events; 13% discontinued because of inadequate seizure control. CONCLUSIONS: From these findings, TPM is well tolerated and provides long-term seizure control in children with partial-onset seizures.

Adolescent↗
PubMed2000

Topiramate in Lennox-Gastaut syndrome: open-label treatment of patients completing a randomized controlled trial. Topiramate YL Study Group.

PURPOSE: The response to topiramate (TPM) as long-term adjunctive therapy was evaluated in patients with Lennox-Gastaut syndrome (LGS) in a long-term, open-label extension to a double-blind, placebo-controlled trial. METHODS: In 97 patients with LGS (mean age, 11 years), dosages of TPM and concomitant antiepileptic drugs (AEDs) were adjusted to optimal clinical response (mean TPM dosage, 10 mg/kg/day). RESULTS: For those patients who had completed 6 months of TPM therapy, drop attacks were reduced > or =50% in 55% of patients; 15% of patients had no drop attacks for > or =6 months at the last visit. After treatment up to 3+ years, 71% of patients who started open-label TPM were continuing therapy at the last visit. CONCLUSIONS: During long-term therapy, TPM is effective and well tolerated in controlling the treatment-resistant drop attacks and seizures associated with LGS.

Adolescent↗
PubMed1999

A double-blind, randomized trial of topiramate in Lennox-Gastaut syndrome. Topiramate YL Study Group.

OBJECTIVE: To evaluate the efficacy and safety of topiramate as adjunctive therapy for Lennox-Gastaut syndrome in a multicenter, double-blind, placebo-controlled trial. BACKGROUND: Conventional antiepileptic drugs are frequently ineffective against multiple-seizure types of Lennox-Gastaut syndrome. METHODS: Ninety-eight patients >1 year to <30 years of age, with slow spike-and-wave patterns on EEG, seizure types including drop attacks, and either a history of or active atypical absence seizures, were assigned to an 11-week, double-blind treatment phase with either topiramate or placebo. Topiramate was titrated to target doses of approximately 6 mg/kg/d. RESULTS: For drop attacks, the most severe seizures associated with this syndrome, the median percentage reduction from baseline in average monthly seizure rate was 14.8% for the topiramate group and -5.1% (an increase) for the placebo group (p = 0.041). Topiramate-treated patients demonstrated greater improvement in seizure severity than did placebo-treated patients based on parental global evaluations (p = 0.037). The percentage of patients with a > or = 50% reduction from baseline in major seizures (drop attacks and tonic-clonic seizures) was greater in the topiramate group (15/46 or 33%) than in the control group (4/50 or 8%; p = 0.002). The most common adverse events in both groups were CNS related; there were no discontinuations from topiramate therapy due to adverse events. CONCLUSIONS: Topiramate adjunctive therapy was effective in reducing the number of drop attacks and major motor seizures and in improving seizure severity as determined by parental global evaluation.

Adolescent↗
PubMed1999

A randomized, placebo-controlled study of topiramate in primary generalized tonic-clonic seizures. Topiramate YTC Study Group.

BACKGROUND AND OBJECTIVE: Topiramate is effective as adjunctive treatment of partial-onset seizures in adults. The efficacy and safety of topiramate as adjunctive therapy for the treatment of primary generalized tonic-clonic (PGTC) seizures were investigated in a randomized, double-blind, placebo-controlled study. METHODS: Eighty patients, 3 to 59 years old, who experienced three or more PGTC seizures during an 8-week baseline phase were randomly assigned to treatment with either topiramate (n = 39) or placebo (n = 41). Topiramate was titrated to target doses of approximately 6 mg/kg/day over 8 weeks and maintained for another 12 weeks. RESULTS: The median percentage reduction from baseline in PGTC seizure rate was 56.7% for topiramate patients and 9.0% for placebo patients (p = 0.019). The proportion of patients with 50% or higher reduction in PGTC seizure rate was 22/39 (56%) and 8/40 (20%) for the topiramate and placebo groups, respectively (p = 0.001). The median percentage reduction in the rate of all generalized seizures was 42.1% for topiramate patients and 0.9% for placebo patients (p = 0.003). The proportions of patients with 50% or higher reductions in generalized seizure rate were 18/39 (46%) and 7/41 (17%) for the topiramate and placebo groups, respectively (p = 0.003). The most common adverse events were somnolence, fatigue, weight loss, difficulty with memory, and nervousness. Treatment-limiting adverse events occurred in one patient in the topiramate group (anorexia and weight loss) and one in the placebo group (granulocytopenia and thrombocytopenia). CONCLUSION: Topiramate is well-tolerated and effective for the adjunctive treatment of PGTC seizures.

Adolescent↗
PubMed1978

Treatment of caustic injuries of the esophagus: a ten year experience.

The methods of managing 32 patients sustaining caustic injuries to the esophagus are assessed. Treatment of these patients must be individualized according to the type of caustic ingested, the degree of burn and other clinical signs. While an aggressive approach is favored for second and third-degree burns in the form of early esophago-gastrectomy with subsequent colon interposition, operation is not necessary. In all patients, particularly those with first-degree burns. The use of antibiotics is recommended as soon as the diagnosis of esophageal injury is established. The efficacy of steroids in preventing stricture formation, especially with third-degree burns, is questioned.

Adult↗
PubMed1978

[Inhibition of rat liver delta 4-3-ketosteroid-5 alpha-reductase by steroids in vitro].

The inhibition of the hydrogenation of testerone to 5alpha-dihydrotestosterone in microsomes of female rat liver has been studied by progesterone-, testosterone- and estradiol derivatives. In the pregnane series, progesterone, 17alpha-OH-progesterone and its acetate were the strongest inhibitors. In the estradiol series, 3-hydroxy-compounds with a CH2X-substituent at 17alpha-position were stronger inhibitors than the respective 3-methoxy derivatives. The most potent inhibitor till now is an estradiol derivative with a SeCN group in 16alpha-position.

5-alpha Reductase Inhibitors↗
PubMed1976

Caustic ingestion and subsequent damage to the oropharyngeal and digestive passages.

The characteristics, diagnosis, and management of oropharyngeal and digestive passage lesions due to ingestion of caustic agents are presented. Previous experimental and clinical studies are reviewed with discussion of the peculiar qualities of the newer caustics. Differentiation in treatment of burns caused by solid and liquid agents is stressed.

Animals↗