Biomedical subjects

B Vazquez

Publications and source records attributed to B Vazquez.

At least 19 recordsLinked to original sources

PubMed1999

Oxcarbazepine: double-blind, randomized, placebo-control, monotherapy trial for partial seizures.

OBJECTIVE: To evaluate the efficacy and safety of oxcarbazepine in a placebo-control trial. METHODS: A multicenter, double-blind, randomized, placebo-control, two-arm parallel group, monotherapy design was used to compare oxcarbazepine administered 1,200 mg twice daily to placebo in hospitalized patients with refractory partial seizures, including simple and complex partial seizures and partial seizures evolving to secondarily generalized seizures. Patients exited the trial after completing the 10-day double-blind treatment phase or after experiencing four partial seizures, two new-onset secondarily generalized seizures, serial seizures, or status epilepticus, whichever came first. RESULTS: Analysis of the primary efficacy variable--time to meeting one of the exit criteria--showed a statistically significant effect in favor of oxcarbazepine (p = 0.0001). The secondary efficacy variables--percentage of patients who met one of the exit criteria (p = 0.0001) and total partial seizure frequency per 9 days during the double-blind treatment (p = 0.0001)--were also statistically significant in favor of oxcarbazepine. CONCLUSION: These results demonstrate that oxcarbazepine given as monotherapy is effective and safe for the treatment of partial seizures in this paradigm.

Adolescent↗

PubMed1998

Application of long chain amine activator in conventional acrylic bone cement.

A long chain acid derivative bearing an aromatic tertiary amine group, 4-N,N-dimethylaminobenzyl laurate (DML), which acts as an activator for the curing of acrylic cements at low temperature, has been synthesized and characterized to reduce the biological adverse effects usually associated with the classical activator N,N-dimethyl-4-toluidine (DMT). The effectiveness of the activator was tested on commercial formulations (e.g., Palacos R) and on experimental bone cements based on poly (methyl methacrylate) by using different benzoyl peroxide/amine molar ratios. The exotherms of polymerization were followed at three different temperatures: 25, 30, and 37 degrees C. The DML activator was found to be more sensitive to temperature than the corresponding DMT. DML provided exotherms of polymerization with decreasing peak temperatures and increasing setting times without impairing the mechanical properties. Residual monomer content was analyzed in a range of activator concentrations by keeping the benzoyl peroxide concentration constant. In all cases the residual monomer content was lower than 5%, indicating its good efficiency in the benzoyl peroxide initiated polymerization.

Bone Cements↗

PubMed1998

An active-control trial of lamotrigine monotherapy for partial seizures.

OBJECTIVE: We report the results of a double-blind, double-dummy, active-control study designed to evaluate the efficacy and safety of lamotrigine (LTG) administered as monotherapy to adult outpatients with partial seizures. BACKGROUND: The effectiveness of LTG as add-on therapy for partial seizures in adults has previously been established. METHODS: After an 8-week baseline during which patients continued their baseline antiepileptic drug (carbamazepine or phenytoin monotherapy), 156 patients were randomly assigned to receive increasing doses of LTG (target 250 mg b.i.d.) or valproic acid (VPA; target low dose of 500 mg b.i.d.) during the first 4 weeks of an 8-week transition period. Carbamazepine or phenytoin was withdrawn over the next 4 weeks; then patients entered a 12-week monotherapy period. Study drug treatment was discontinued in patients who met predetermined escape criteria for seizure worsening. RESULTS: More patients receiving LTG were successfully maintained on monotherapy compared with patients receiving VPA (56% versus 20%; p < 0.001). The time to meet the escape criteria was also significantly longer in LTG-treated patients (median = 168 days) than in VPA-treated patients (median = 57 days; p = 0.001). The incidence of adverse events during the monotherapy period was lower than during the transition period. Four LTG patients and five VPA patients reported serious adverse events. Two of those patients experienced a rash that led to withdrawal soon after adding LTG to carbamazepine. CONCLUSIONS: We conclude that LTG is effective and well tolerated when administered as monotherapy in adult patients with partial seizures.

Adolescent↗

PubMed1997

Effect of crosslinking agents on acrylic bone cements based on poly(methylmethacrylate).

Three different crosslinking agents were added to the monomer content of the bone cement formulation based on poly(methylmethacrylate), PMMA, in various concentrations, and their effects on the curing parameters and mechanical properties were determined. The different crosslinking agents were dimethacrylates containing a range of chain lengths and degrees of flexibility. For the parent formulation of the bone cement, PMMA powder was used, and the properties and kinetics of curing were compared for the same system with and without crosslinking agents. It was found that at low concentrations of crosslinking agents, the mechanical properties were superior but steadily decreased with increasing concentrations. Poly(ethyleneglycoldimethacrylate), EGDMA(400), even when used at very low concentrations, produced a steady improvement in the mechanical properties and could be used in cement formulations with a view to reducing creep and improving mechanical properties.

Acrylates↗

PubMed1997

Application of tertiary amines with reduced toxicity to the curing process of acrylic bone cements.

4-Dimethylaminobenzyl alcohol (DMOH) and 4-dimethylaminobenzyl methacrylate (DMMO) were used as the activators in the benzoyl peroxide initiated redox polymerization for the preparation of acrylic bone cement based on poly(methylmethacrylate) beads of different particle size. The residual monomer content of the cured cements was about 2 wt %, independent of the redox system used in the polymerization, indicating that the activating effect of the tertiary aromatic amines DMOH or DMMO was sufficient to reach a polymerization conversion similar to that obtained with the benzoyl peroxide (BPO) N,N-dimethyl-4-toluidine (DMT) system. The BPO/DMOH and BPO/DMMO redox systems provided exotherms of decreasing peak temperature and increasing setting time, and the cured materials presented higher average molecular weight and similar glass transition temperatures in comparison with those obtained when DMT was used as the activator. In addition, these activators are three times less toxic than the classical DMT.

Acrylates↗

PubMed1997

Dissociation in epilepsy and conversion nonepileptic seizures.

PURPOSE: We examined the dimensionality of the item content of the Dissociative Experiences Scale (DES) in relation to the clinical diagnosis of conversion nonepileptic seizures (C-NES) versus complex partial epilepsy (CPE). METHODS: The DES was administered to a sex- and age-matched sample of 132 patients with C-NES and 169 with CPE and was factor analyzed with principal components analysis (PCA) with varimax rotation. RESULTS: The mean total DES score was 15.1 in the C-NES group and 12.7 in the CPE group (p = 0.079). The factors obtained by PCA differentiated the CPE and C-NES groups more strongly than did the total DES score. The factor accounting for the most variance, interpreted as "depersonalization-derealization," was significantly greater in C-NES than CPE (p = 0.005). An "absorption-imaginative involvement" factor, which included some of the clinical features of posttraumatic stress disorder was elevated only in subjects reporting histories of childhood abuse (p = 0.001) regardless of the diagnosis of CPE or C-NES. An "amnestic" factor appearing to represent memory problems related to neurologic impairment showed a trend toward elevation in CPE (p = 0.056) and may have confounded the CPE versus C-NES distinction using total DES scores. CONCLUSIONS: The DES has separate underlying dimensions that appear to relate distinctively to depersonalization and derealization, childhood trauma, and neurologic impairment. The heterogeneous item content of the DES is a potential confound that should be appreciated when this instrument is used to study dissociation in neuropsychiatric populations.

Adult↗

PubMed1997

Frontal functions in juvenile myoclonic epilepsy.

The authors investigated cognition in juvenile myoclonic epilepsy (JME), focusing on frontal functions as suggested by maximal spatial distribution of epileptiform activity seen over frontocentral regions. Fifteen patients with JME (mean age, 34.3 years; mean estimated IQ 101) were administered a battery of tests sensitive to frontal dysfunction. The number of patients with impaired test performance and the frequency of impairment per test were calculated. Performance on selected tests was compared with that of 15 patients with temporal lobe epilepsy (TLE) who were matched for estimated IQ using paired t-tests. Although the performance of the group with JME was not uniform--some patients showed marked impairment whereas others showed little or no deficit--a high frequency of impairment was found on tests of concept formation-abstract reasoning and mental flexibility, cognitive speed, and planning and organization. Significant differences were found between the group with JME and the group with TLE on tests requiring mental flexibility and concept formation-abstract reasoning. In conjunction with studies demonstrating intractable seizures in approximately 20% of patients, the results from this study suggest that JME is not a uniformly benign condition. Frontal deficits may have maladaptive behavioral consequences suggestive of personality dysfunction, as described anecdotally by previous investigators.

Adolescent↗

PubMed1996

Simple and sensitive high-performance liquid chromatography--fluorescence method for the determination of citrinin application to the analysis of fungal cultures and cheese extracts.

A new and highly sensitive method for the detection of the important mycotoxin, citrinin, has been developed. Spectroscopic studies demonstrate that the fluorescence of this metabolite is influenced by the pH of the environment. This fact was exploited in the chromatographic determination of citrinin with fluorescence detection. The proposed method, based on the addition of 1 M hydrochloric acid as an acidic post-column reagent, has a limit of detection of 0.9 center dot 10(-7) M. Analytical validation shows that linearity can be assumed from 2 center dot 10(-7) to 10(-4) M citrinin. The repeatability and reproducibility are satisfactory, with R.S.D. = 5.1% (n = 9, c = 10(-5) M) and R.S.D. = 7.2% (n = 9, c = 10(-5) M). The method was also applied to the determination of this mycotoxin produced by mould cultures isolated from soft cheese and also from soft cheese and also from cheese extracts spiked with citrinin. The specificity of the method is demonstrated and the necessity for post-column acidification is illustrated on real samples.

Cheese↗

PubMed1996

Clinical features of neocortical temporal lobe epilepsy.

Few studies have examined the clinical features of neocortical temporal lobe epilepsy (NTLE) in carefully selected patients. We reviewed records from 21 patients with NTLE, defined by intracranial electroencephalogram (EEG), who have been seizure free for 1 year or more following temporal lobectomy. The mean age of onset at the time of first seizure was 14 years (range, 1-41 years). Febrile seizures were reported in only 2 patients (9.5%). In contrast to prior mesial temporal lobe epilepsy (MTLE) studies, seizure-free intervals between the initial cerebral insult or first seizure and habitual seizures were uncommon. Possible or known risk factors for epilepsy were reported in 13 of 21 patients (62%). Fifteen (71%) patients reported auras, with experiential phenomena being the most common type. Magnetic resonance imaging was normal or nonspecific in 15 patients, revealed mild hippocampal atrophy in 2, tumors in 2, and heterotopic gray matter and hippocampal atrophy in 1, and cortical dysgenesis in 1. Neuropsychological testing showed deficits consistent with the seizure focus in 13 patients (62%), and Wada test showed ipsilateral memory deficits in 10 (48%). The most common behavioral manifestation was a motionless stare at ictal onset (48%). In contrast to prior studies of MTLE, only 1 NTLE patient had frequent independent, contralateral temporal lobe epileptiform spikes on scalp EEG.

Adolescent↗

PubMed1996

Clinical profile of patients with epileptic and nonepileptic seizures.

Epileptic seizures (ES) and nonepileptic seizures (NES) often coexist in patients with treatment-refractory seizures. There are few data on ictal features of these different seizure types in the same patient. We identified 20 patients with ES from a group of 99 NES patients (ES/NES) and compared this group with patients with only ES or NES. All 20 ES/NES patients developed NES after ES. Clinical features of NES clearly differed from ES in 18 of 20 cases. In patients with ES/NES their ES were similar to seizures in patients with only ES, and their NES were similar to spells in patients with only NES. ES/NES patients were similar to ES patients in electrodiagnostic and neuroimaging studies, and similar to NES patients in psychiatric interviews and inventories. The clinical manifestations of ES and NES in the same patient are usually different. Both types of events may be stereotypic and can be distinguished and characterized during video-EEG recording. Determining what events are more prevalent or disturbing is critical. Psychiatric and antiepileptic drug treatment may be provided accordingly.

Amnesia↗

PubMed1995

Psychiatric classification of nonconversion nonepileptic seizures.

OBJECTIVE: To determine the frequency and type of non-conversion nonepileptic seizures (NES). BACKGROUND: Although conversion disorder is the most common psychiatric disorder among patients with NES, many patients with nonepileptic paroxysmal behavioral events have other psychiatric disorders, with natural histories and treatments different from those of conversion disorder. DESIGN: Retrospective review of a series of consecutive admissions for video-electroencephalography monitoring. All patients identified with NES were interviewed by a psychiatrist. Patients with conversion and other psychiatric disorders were divided into separate groups. SETTING: A comprehensive epilepsy center. RESULTS: Twenty-one patients evaluated for possible epileptic seizures had a psychiatric disorder other than conversion that accounted for their events. Among these patients, Diagnostic and Statistical Manual of Mental Disorders, Revised Third Edition (DSM-III-R) anxiety disorders (n = 9) were the most common diagnosed category, followed by all forms of psychotic disorders (n = 7) and impulse control problems in the setting of attention deficit disorder residual type (n = 2). In contrast to 71 patients with conversion NES seen over the same period of time, the non-conversion group showed no female predominance and the nonconversion patients were significantly less likely than the conversion patients to have been physically or sexually abused in childhood or adolescence. CONCLUSIONS: These results support the validity of the nosologic distinction of nonconversion from conversion NES and suggest that DSM-III-R anxiety disorders are an important diagnostic confound in clinical epilepsy.

Conversion Disorder↗

PubMed1995

Arachidonic acid metabolism modulates vasopressin-induced renal vasoconstriction.

Previous studies have shown that cytochrome P450-Arachidonic Acid (P450-AA) metabolites modify the vascular tone of several vessels and that vasopressin (AVP) stimulates P450-AA metabolism. Thus, in the present study, we decided to investigate if the vasoconstrictor effect of AVP is related to activation of P450-AA metabolism. We used the isolated perfused kidney of a rat, to test this hypothesis. Bolus injection of AVP (5.5, 11, 22 and 45 ng) increased the perfusion pressure of the isolated kidney of a rat by 66 +/- 2, 87 +/- 4, 110 +/- 2 and 130 +/- 3 mmHg respectively. This AVP-induced vasoconstriction was significantly reduced by inhibition of AA metabolism with ETYA, or 7 ethoxyresorsorufin (7ER). Furthermore, in vivo induction of P450 system with dexamethasone, enhanced the AVP-induced vasoconstrictor effect. Conversely, depletion of P450 system with SnCl2 diminished the vasoconstrictor response to AVP. Measurement of P450-14cAA metabolites in the renal effluent, showed the presence of 3 radioactive peaks. The % of the recovered radioactivity was 0.12 +/- 0.05%, 0.11 +/- 0.03% and 1.13 +/- 0.5% and corresponded to Dihydroxyeicosatrienoic acids (DHTs), Hydroxyeicosatetraenoic acids (HETEs) and Epoxyeicosatrienoic acids (EETs) respectively, when kidneys were stimulated by AVP (300 ng) the % recovered were 0.34 +/- 0.01%, 0.38 +/- 0.01% and 3.11 +/- 0.7% for the DHTs, HETEs and EETs respectively. Treatment with dexamethasone or SnCl2 potentiated or inhibited the AVP-dependent release of the P450-AA metabolites. In conclusion, we suggest that AVP stimulates AA metabolism via P450 pathway in the kidney and that these AA metabolites participate in the vasoconstrictor effect of AVP in the renal circulation.

5,8,11,14-Eicosatetraynoic Acid↗

PubMed1995

Psychogenic basilar migraine: report of four cases.

We discuss four patients with the clinical diagnosis of basilar migraine and suspected coexisting epilepsy who were referred to our epilepsy center. Their symptoms suggested episodic dysfunction in the distribution of the basilar artery, followed by pulsating headache with nausea. Verbal unresponsiveness and sensory symptoms occurred in all four patients; two also had focal paresis or jerking movements. Diagnostic studies excluded other disorders with similar symptoms. None of the patients improved with antimigraine or antiepileptic drugs. Provocation tests with suggestion elicited typical events in three patients and aura and headache in one patient. There were no EEG or ECG abnormalities during spontaneous or provoked episodes. Two patients improved with psychiatric treatment. Conversion disorder or malingering should be considered in patients whose symptoms of basilar migraine are atypical or refractory to treatment.

Adult↗

PubMed1994

Multiple subpial transections in the language cortex.

Multiple subpial transections (MST) were made in language cortex in three patients with medically refractory partial epilepsy. All patients were mapped with extra-operative stimulation using subdural grids over the dominant temporal, frontal and parietal convexity. Two patients had anterior temporal lobectomy and MST in posterior language cortex. One patient who had undergone a previous frontal tumour resection had only MST over the frontoparietal convexity, including frontal and parietal language areas. Both patients with MST in the posterior language cortex had postoperative language dysfunction, which had improved significantly by 9 months after surgery. The patient with MST in frontoparietal language areas had improved language functions immediately postoperatively. The two men with anterior temporal lobectomies and MST are seizure-free at 1 year follow-up and the woman with frontoparietal MST has had a > 70% reduction in seizure frequency at 1 year follow-up.

Adult↗

PubMed1994

New antiepileptic drugs for children: felbamate, gabapentin, lamotrigine, and vigabatrin.

After a 15-year hiatus, several new antiepileptic drugs have been approved or are under Food and Drug Administration investigation for use in the United States. This article reviews four of these new drugs--felbamate, gabapentin, lamotrigine, and vigabatrin. Although these drugs have been primarily developed for use in adults with partial seizures, they will also likely be used in children with partial epilepsy. Pediatric experience with several of these drugs has demonstrated safety and efficacy in other seizure types and epilepsy syndromes. These drugs will be an important addition to the therapeutic armamentarium for pediatric epilepsy. Additional studies are needed to fully explore the safety and efficacy of these drugs in a variety of pediatric epilepsies and to compare them to existing antiepileptic drugs.

Acetates↗

PubMed1994

The prolonged QT syndrome presenting as epilepsy: a report of two cases and literature review.

The prolonged QT syndrome is associated with ventricular tachyarrhythmias and sudden death. We report two patients and review eight previously reported cases of this syndrome, presenting as epilepsy. The average age at the time of the first convulsion was 4.7 years. Episodes were often infrequent, and the time to correct diagnosis ranged from 1 to 28 years. Only one-half the patients had histories suggestive of a familial syndrome. Presyncopal complaints and "lifelessness" prior to seizure activity were common findings in retrospect. Beta-blockade was effective in preventing recurrences in all patients who received treatment.

Adult↗

PubMed1993

Nonepileptic seizures and childhood sexual and physical abuse.

Nonepileptic seizures (NES) must be distinguished from epilepsy to avoid the adverse effects of unnecessary antiepileptic drugs and to initiate appropriate psychiatric treatment. A higher frequency of prior sexual abuse has been suspected in NES, although no prospective controlled study has compared patients with NES and epilepsy. A series of patients with conversion disorder presenting as epilepsy and 140 patients with complex partial epilepsy (CPE) without evidence of conversion were selected from a series of consecutive admissions to a comprehensive epilepsy center. The groups did not differ with respect to age, years of education, race, or marital status, but the percentage of women was greater in the conversion NES group (73.2%) than in the CPE control group (50.7%; p < 0.002). The frequency of a history of sexual or physical abuse was greater in the NES group (32.4%) than in the CPE controls (8.6%; p < 0.000). Severity of sexual but not physical abuse was significantly greater in the NES group relative to controls (p < 0.05). There was a trend for a closer relationship of the perpetrator of sexual abuse to the victim among the NES patients compared with CPE controls (p < 0.1). These results support the impression that childhood abuse is more common among patients with conversion NES than with epilepsy, and suggests that in some cases childhood abuse may be a contributory pathogenetic factor.

Adult↗

PubMed1993

Lateralizing significance of head and eye deviation in secondary generalized tonic-clonic seizures.

We studied 92 secondary generalized tonic-clonic seizures (SGTCS) in 29 patients with a clearly lateralized seizure focus using video-EEG telemetry. An examiner, blind to the EEG, reviewed direction and type (forced versus nonforced) of head/eye deviation (HD). Forced HD consisted of sustained, unnatural tonic or clonic movements. Nonforced HD consisted of sustained deviations that were neither tonic nor clonic and were similar to volitional head movements. Eighty-three of the 92 SGTCS (26 of 29 patients) had lateralized and sustained HD. The direction of HD was contralateral in over 90% of seizures when the movement either (1) continued as the seizure generalized, or (2) occurred in the 10 seconds prior to generalization. The direction of HD was ipsilateral in over 90% of seizures if the movement ended before the seizure began to generalize (in all cases, the movement ended more than 10 seconds before generalization). HD occurring within the first 10 seconds after seizure onset was not of lateralizing significance. Forced HD was 89% contralateral, while nonforced HD was not of lateralizing significance. HD in SGTCS provides information on seizure focus lateralization.

Adolescent↗