Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: UMLS:C0036572 (seizures)
 80,221 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Effects of felodipine, the calcium channel blocker, on the electroshock, pentetrazole-, aminophylline-, and pilocarpine-induced seizures and on the anticonvulsant activity of different antiepileptic drugs against maximal electroshock were examined in mice. Felodipine increased the threshold for electroconvulsions. The drug exerted also a protective effect against pentetrazole-induced seizures, but not against aminophylline- and pilocarpine-induced seizures. The protective efficacy of diazepam and diphenylhydantoin (but not phenobarbital and valproate) against electroconvulsions was significantly enhanced by felodipine. A pharmacokinetic interaction did not seem to be responsible for the interaction of felodipine with antiepileptic drugs in the maximal electroshock test.
 ...
PMID:Influence of felodipine on experimental seizures and activity of different antiepileptic drugs in mice. 966 35

The efficacy of Flunarizine (FLU), a calcium channel blocker, in combination with conventional antiepileptic drugs, phenytoin (PHT), carbamazepine (CBZ), sodium valproate (VPA), and ethosuximide (ESM), at ED50 doses, were examined for protective effects against maximal electroshock seizures (MES) and pentylenetetrazol (PTZ) induced seizures in mice. In both models, only VPA and FLU showed significantly enhanced protection, which was additive ie. 100% protection. In the MES test, though FLU combined with PHT did show a slightly enhanced protection (66.6%), with CBZ there was no enhancement as compared to either drug alone. In the PTZ test, FLU with ESM showed 83% protection this however was not statistically significant. The findings of this study in mice suggest that FLU would be a suitable candidate for add-on therapy with VPA for clinical epilepsy.
 ...
PMID:Additive anticonvulsant effect of flunarizine and sodium valproate on electroshock and chemoshock induced seizures in mice. 974 53

It seems clear that the abundance of potential treatment options reflects the dearth of proved, effective options. Thus, although we appear to be on the brink of many potentially major breakthroughs in treatment, there currently remains a multitude of unanswered questions and the need for further study. At this point clinical recommendations must be limited to supportive care with moderation: oxygenation without hyperoxia; ventilation without hypocarbia; avoiding extremes of blood pressure, hematocrit, blood glucose, and body temperature. Unfortunately, data from human trials are extremely limited and often poorly controlled. Furthermore, even those few existing human studies have rarely--if ever--dealt with newborns infants (Table 2). In addition, many of the existing studies do not relate to generalized asphyxia but rather to single-organ reperfusion insults. Finally, there is the critical issue of timing. Unfortunately, much of the existing experimental data relate to prophylaxis rather than treatment, severely limiting their potential for clinical applicability. Interventions may have quite different effects when administered at different phases of this most intricate process. Hyperglycemia, for example, may be neuroprotective before an insult but detrimental if induced after an asphyxial episode. Conversely, the NMDA blocker MK-801 can adversely affect outcome when given before a global asphyxial insult but can reduce seizure-related damage when given during the hyperexcitability phase. Insulin-like growth factor is also neuroprotective only when given after an insult, but it is not helpful if given before. An intimate understanding of the pathophysiologic processes involved is essential before any attempts at applying the diverse data derived from numerous animal studies to the human situation in an intelligent manner. Future studies may focus on cocktails of different mixtures of the compounds discussed or on single multipotential drugs, which would make possible a multipronged approach. However, it is essential to investigate fully the potential for toxic drug interactions, as some combinations may be produce serious consequences. For example, Gluckman and Williams evaluated the potential of combining calcium channel blockers with NMDA receptor antagonists in hypoxic-ischemic rats and found that this combination led to rapid cardiovascular collapse. Other enticing approaches for future investigations will probably include some genetic-engineering-related studies in attempt to enhance endogenous antioxidant defenses with regulon stimulation or the administration of neurotrophic growth factors. Unavoidably, the trip from the laboratory to the bedside must of necessity be an arduous and rigorous one.
 ...
PMID:Ischemia and reperfusion injury. The ultimate pathophysiologic paradox. 977 46

Tottering mice inherit a recessive mutation of the calcium channel alpha1A subunit that causes ataxia, polyspike discharges, and intermittent dystonic episodes. The calcium channel alpha1A subunit gene encodes the pore-forming protein of P/Q-type voltage-dependent calcium channels and is predominantly expressed in cerebellar granule and Purkinje neurons with moderate expression in hippocampus and inferior colliculus. Because calcium misregulation likely underlies the tottering mouse phenotype, calcium channel blockers were tested for their ability to block the motor episodes. Pharmacologic agents that specifically block L-type voltage-dependent calcium channels, but not P/Q-type calcium channels, prevented the inducible dystonia of tottering mutant mice. Specifically, the dihydropyridines nimodipine, nifedipine, and nitrendipine, the benzothiazepine diltiazem, and the phenylalkylamine verapamil all prevented restraint-induced tottering mouse motor episodes. Conversely, the L-type calcium channel agonist Bay K8644 induced stereotypic tottering mouse dystonic at concentrations significantly below those required to induce seizures in control mice. In situ hybridization demonstrated that L-type calcium channel alpha1C subunit mRNA expression was up-regulated in the Purkinje cells of tottering mice. Radioligand binding with [3H]nitrendipine also revealed a significant increase in the density of L-type calcium channels in tottering mouse cerebellum. These data suggest that although a P/Q-type calcium channel mutation is the primary defect in tottering mice, L-type calcium channels may contribute to the generation of the intermittent dystonia observed in these mice. The susceptibility of L-type calcium channels to voltage-dependent facilitation may promote this abnormal motor phenotype.
 ...
PMID:L-type calcium channels contribute to the tottering mouse dystonic episodes. 988 94

Recent application of genetic analysis to rare, hereditary epilepsies has resulted in the identification of mutations in genes encoding ion channels or functionally related proteins in several human and animal syndromes. Reviewed here are selected human and murine epilepsies that result from ion channel mutations. In humans, three autosomal-dominant disorders--benign familial neonatal convulsions, nocturnal frontal lobe epilepsy, and "generalized epilepsy with febrile seizures plus"--result from mutations affecting voltage-sensitive potassium channels, a central nicotinic acetylcholine receptor, and a voltage-sensitive sodium channel, respectively. In mice, four genetically distinct, autosomal-recessive models of absence epilepsy are caused by mutations in genes encoding three types of calcium channel subunits and a sodium-hydrogen ion exchanger. These findings suggest that variation in genes encoding ion channels could determine susceptibility to common human epilepsies.
 ...
PMID:Ion channels and the genetic contribution to epilepsy. 1002 38

Eclampsia continues to be a major cause of maternal morbidity and mortality rates, especially in underdeveloped nations. Our data indicate that eclampsia may represent the end stage of at least two very different pathophysiological pathways: one in which cerebral perfusion is low because of vasospasm and another in which cerebral perfusion is increased because of abnormal autoregulation and a failure of the normal protective mechanisms. Magnesium sulfate has been extensively used in the management and prevention of eclamptic seizures in the United States and has been recently shown to be superior to both diphenylhydantoin and diazepam. We have shown that magnesium sulfate is a potent vasorelaxant and that its action may depend on improving cerebral perfusion. Nimodipine, a calcium channel blocker with selective cerebrovascular effect, is currently under investigation in severe preeclampsia. The data show that it is as effective as magnesium sulfate in preventing eclampsia, with less maternal and fetal side effects. Magnesium sulfate and nimodipine have opposite effects on the estimated cerebral perfusion pressure as determined with the Doppler ultrasound. We speculate that the estimated cerebral perfusion pressure may be used to determine the type of cerebrovascular abnormality and the most appropriate treatment in each individual patient with preeclampsia.
 ...
PMID:Prevention of eclampsia. 1010 72

This paper describes the synthesis and preliminary anticonvulsant evaluation of some GABA analogues i.e. derivatives of 2-(4-phenylpiperazino)- or 2-(4-benzylpiperidino)-GABA (5, 6), N-substituted amides of 2-(4-phenylpiperazino)-4-phthalimidobutyric acid and N-substituted amides of 2-(4-phenylpiperazino)-GABA. N-Substituted amides of 2-(4-phenylpiperazino)-4-phthalimidobutyric acid (7-11) were prepared by condensation of the acid with the corresponding derivatives of benzylamine in the presence of different coupling reagents (2-chloro-4,6-dimethoxy-1,3,5-triazine (CDMT) and carbonyldiimidazole (CDI). N-Substituted benzylamides of 2-(4-phenylpiperazino)-4-aminobutyric acid (12-14) were prepared by hydrazinolysis of amides 9-11. Anticonvulsant activities were determined in mice (for all compounds) and in rats using the subcutaneous metrazol (scMet) and maximal electroshock (MES) screens. The amides (12-14) showed protection against MES and/or scMet seizures in mice. N-(4-Methoxybenzyl)-2-(4-phenylpiperazin-1-yl)-4-aminobutyric amide (13) was the most effective and displayed anticonvulsant activity in both tests at doses of 100-300 mg/kg in mice and at 30 mg/kg in the MES screen in rats. The active compounds (12-14) were tested for their ability to displace [3H]nitrendipine binding sites (voltage-sensitive calcium channel receptors) from rat cortex. Amide 13 was the most active both in pharmacological and biochemical tests. These preliminary results suggest that the anticonvulsant activity of compounds 12-14 may be related to their influence on voltage-sensitive calcium channel receptors.
 ...
PMID:Synthesis, physicochemical properties, anticonvulsant activities and voltage-sensitive calcium channels affinity of N-substituted amides of alpha-(4-phenylpiperazino)-GABA. Part 3: Search for new anticonvulsant compounds. 1023 33

The mutated gene in the lethargic (Cacnb4lh) mouse model of absence seizures encodes the beta4 subunit of voltage-gated calcium channels (VGCCs), leading to decreased mRNA expression of a beta4 subunit that is truncated and cannot bind to alpha1 subunits of VGCCs. In this study we accomplished two goals. First, we studied the functional consequence of altered VGCCs by examining the effects of a selective P/Q-type channel antagonist on KCl-induced (45)Ca(2)(+) uptake in brain synaptosomes from Cacnb4lh homozygotes and non-epileptic controls (designated by +/+). We found that depolarization-induced (45)Ca(2)(+) uptake was significantly reduced in the brains of Cacnb4lh homozygotes, and that the reduced uptake was completely accounted for by reduced function of P/Q-type calcium channel. Second, we examined VGCC subunit composition to determine if other subunits were altered in addition to the mutation affecting beta4 subunits in Cacnb4lh homozygotes; when alterations were found, we determined if they were regional or global. We used in situ hybridization histochemistry (ISHH) to analyze the neuro-anatomic distribution of beta4, beta1b, beta2, beta3, alpha1A, alpha1B, alpha1C, alpha1E, and alpha1G subunit mRNAs in brain sections from matched Cacnb4lh homozygotes and +/+ controls. Our results indicated that expression of beta4 subunit mRNA is globally reduced throughout the brains of Cacnb4lh homozygotes, in contrast to a small but significant global increase in the expression of beta3 subunit mRNA. There were no significant differences in expression of the other VGCC subunit mRNAs examined. Together, these findings indicate that a host of changes in VGCC subunit composition accompany reduced function of P/Q-type channels in homozygous lethargic mice.
 ...
PMID:Decreased (45)Ca(2)(+) uptake in P/Q-type calcium channels in homozygous lethargic (Cacnb4lh) mice is associated with increased beta3 and decreased beta4 calcium channel subunit mRNA expression. 1040 81

Zonisamide (ZNS) is a relatively new antiepileptic medication currently available in Japan. Attempts to market the drug in the United States were thwarted by reports of nephrolithiasis by European and American investigators. However, successful marketing of the drug in Japan has resulted in a renewed interest in bringing the drug to the United States. Japanese experience with ZNS showed a broad spectrum of efficacy in the treatment of seizures, including infantile spasms and myoclonic seizures. A neuroprotective role and an antimanic effect have also been reported. The exact antiepileptic mechanism of action of ZNS is not known, but it has dose-dependent sodium channel blocking and T-type calcium channel blocking properties and free radical scavenging actions. Recommended initial adult dosage in Japan is 100-200 mg/d, increased if necessary to 200-400 mg/d, up to a maximum of 600 mg/d. In children, initial dosage is 2-4 mg/kg/d, increased if necessary to 4-8 mg/kg/d up to a maximum of 12 mg/kg/d. The recommended therapeutic plasma ZNS concentration is 10-20 mg/L. Adverse events, most notably drowsiness, loss of appetite, gastrointestinal problems, and CNS toxicity, have been noted with plasma ZNS concentrations of > 30 mg/L. A drug rash also has been reported.
 ...
PMID:Zonisamide: a new antiepileptic drug. 1044 47

The most venomous scorpion species are Buthotus tamulus of India, the Leiurus quinquestriatus and Androctonus crassicauda of North Africa and the Middle East, the Tityus serrulatus of Brazil, and the Centruroides suffussus of Mexico. The severity of scorpion envenomation varies with the scorpion's species, age, and size, and is much greater in children. Systemic intoxication reflects the overstimulation of the CNS, the sympathetic and parasympathetic nervous system. Severity ranges from local pain and paresthesia to fatal cardiotoxicity and encephalopathy. Symptoms include: agitation, tachycardia, vomiting, abdominal pain, salivation, diaphoresis, dehydration, muscle rigidity and twitching, tremor, seizures, coma, pupillary changes, hyperthermia, tachyarrythmias and occasionally bradyarrhythmias, hypertension, and less often hypotension, cardiac failure, and priapism in males. Laboratory abnormalities include: hyperglycemia, leucocytosis, transient elevation of cardiac and pancreatic enzymes, ischemic changes in the ECG, and evidence of cardiac dysfunction on echocardiography. The principles of management are: observation, cardiac monitoring, supportive treatment with intravenous fluids and electrolytes, and a meticulous use of cardiovascular agents: vasodilators, adrenergic antagonists, or calcium channel blockers in the hypertensive phase; and inotropic agents in the event of hypotension. Antiarrhythmics such as lidocaine, may be required. There is increasing evidence for the efficacy of specific antivenom. The advance in supportive care and antivenom efficacy has markedly improved the outcome of patients with scorpion envenomation.
 ...
PMID:Clinical manifestations and management of scorpion envenomation. 1044 63


<< Previous 1 2 3 4 5 6 7 8 9 10 Next >>