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Objective To report the clinical features and inwardly rectifying potassium channel 18 (KCNJ18) gene mutation in a group of patients with thyrotoxic periodic paralysis (TTP).Methods Fiftyseven TTP cases (55 male and 2 female) were collected in our clinic from July 2002 to October 2011.The KCNJ18 gene was directly sequenced in 57 TTP patients and 50 health Chinese controls through the nested PCR.According to the results of gene screening,the clinical features of KCNJ18 patients and non-KCNJ18 patients were retrospectively summarized and analyzed.Results In 4 male patients with TPP,we found 3 novel heterogeneous mutations (p.Q126X,p.K360T,p.E388K) and 1 reported mutation (p.A200P) in the KCNJ18 gene.The age of onset was 19-25 years old,and the duration ranged from 2 to 8 hours.The 4 patients all presented severe muscle weakness.The attacks of muscle weakness preceded overt symptoms of hyperthyroidism in the 4 patients. Three patients showed recurrent weakness during the 13-28 months follow-up,while the episodic weakness never appeared when patients got euthyroid. Conclusions The mutations in the KCNJ18 gene are responsible for a part of Chinese patients with TPP.The patients with KCNJ18 mutations have a shorter disease course,severer manifestation,and higher prevalence of recurrence as compared with those TPP patients without KCNJ18 mutations.
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Objective To survey gene expression profiles in nonlesional refractory temporal lobe epilepsy(TLE)and to further verify the difference of gene expression.thus to evaluate the possible molecular pathogenesis of this kind of epilepsy that can help to supply a new way for the diagnosis and treatment.Methods The TLE samples and control cases were studied by means of cDNA microarray consisting of 1 8 000 genes.Reverse transcription polymerase chain reaction(RT-PCR)Was performed to measure the expression alterations of SH3GL2.BTNN2A2 and KCNJ4 mRNA in temporal cortex samples from patients who had undergone temporal lobectomy surgery for intractable epilepsy.Tissue from 10 subjects who did not have epilepsy served as controls.Results The known genes differently expressed in those TLE samples involved immunity correlation factor genes,signal conduction genes,ion channel transportation genes;mitochondria function genes and SO on were identified.Among which.the expression of SH3GL2 mRNA Was significantly increased in epileptic brain(1.022±0.547)compared with the controls(0.446±0.171,t=-3.181).In TLE group(0.481±0.196),the expression of BTN2A2 mRNA was also significantly higher than that of control subjects(0.243±0.111,t=3.351).Compared with control group(O.795±0.112),the expression of KCNJ4 mRNA Was significantly decreased in TLE patients(0.438±0.178).Conclusions cDNA microarray is an efficient and high.throughout method to survey gene expression profiles in intractable temporal lobe epilepsy.The variation of those gene expressions might be a potential etiological agent for TLE that may offer a novel target for anticonvulsant therapy.
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Objective To evaluate the possible molecular pathogenesis of intractable temporal lobe epilepsy. The potassium ion channel gene KCNJ4 encodes one of the subfamilies of Kir channels, Kir2.3 subunit, which may play an important role in modulating neuronal excitation. Interference in the function or expression of this gene would cause disturbance of ionic concentrations, thus leading to seizure activity. Methods Reverse transcription polymerase chain reaction (RT-PCR) and Western-blot analysis were used to measure the expression alterations of KCNJ4 mRNA as well as its protein product Kir2.3 channel in temporal cortex samples from patients who had undergone temporal lobectomy for intractable epilepsy (n=12). Tissue from 10 subjects who did not have epilepsy served as controls. Results The expression of KCNJ4 mRNA (0.438?0.178) and its protein Kir2.3 (M 50=0.063) were significantly decreased in epileptic brain compared with the controls (P
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Objective To study the effect of ketamine on inward rectifier potassium currents(I_k1)in isolated rat ventricular myocytes using whole-cell patch clamp technique.Methods Adult Wistar rats of both sexes were anesthetized with pentobarbital.The hearts were removed and ventricular myocytes were prepared by the technique described by Liu et al.Whole-cell patch clamp technique was used to study I_(k1) in isolated rat ventricular myocytes The changes in I_(KI) produced by 100 ?mol?L~(-1) with different holding potentials or by different concentrations of ketamine with holding potential of-120 mV were analyzed.Results Ketamine 100 ?mol?L~(-1) inhibited the Ira without any significant effects on reverse potential (-50--60 mV)and the shape of the Ⅰ-Ⅴ curve.Ketamine inhibited I_(k1) evoked by a holding potential of-120 mV in a dose-dependent manner with a mean IC_(50) value of (162.3?8.4)?mol?L~(-1).Conclusion Ketamine significantly inhibits I_(k1) in ventricular myocytes. This may explain the prolonged duration of action potential of ventricular myocyte produced by ketamine.