Inhibitory effects of the atypical antipsychotic, clozapine, on voltage-dependent K+ channels in rabbit coronary arterial smooth muscle cells

To investigate the adverse effects of clozapine on cardiovascular ion channels, we examined the inhibitory effect of clozapine on voltage-dependent K+(Kv) channels in rabbit coronary arterial smooth muscle cells. Clozapine-induced inhibition of Kv channels occurred in a concentration-dependent manner with an halfinhibitory concentration value of 7.84 ± 4.86 µM and a Hill coefficient of 0.47 ± 0.06.Clozapine did not shift the steady-state activation or inactivation curves, suggesting that it inhibited Kv channels regardless of gating properties. Application of train pulses (1 and 2 Hz) progressively augmented the clozapine-induced inhibition of Kv channels in the presence of the drug. Furthermore, the recovery time constant from inactivation was increased in the presence of clozapine, suggesting that clozapineinduced inhibition of Kv channels is use (state)-dependent. Pretreatment of a Kv1.5 subtype inhibitor decreased the Kv current amplitudes, but additional application of clozapine did not further inhibit the Kv current. Pretreatment with Kv2.1 or Kv7 subtype inhibitors partially blocked the inhibitory effect of clozapine. Based on these results, we conclude that clozapine inhibits arterial Kv channels in a concentrationand use (state)-dependent manner. Kv1.5 is the major subtype involved in clozapineinduced inhibition of Kv channels, and Kv2.1 and Kv7 subtypes are partially involved.

The Association between Cerebrospinal Fluid Pleocytosis and Clinical Manifestations of Enteroviral Meningitis in Children

OBJECTIVE: Enteroviruses are major causes of aseptic meningitis in children. This study aimed to describe the clinical manifestations of enteroviral meningitis according to the presence of cerebrospinal fluid (CSF) pleocytosis, and to investigate the factors influencing the CSF pleocytosis in children with this condition. METHODS: Eighty children with enteroviral meningitis treated at Soonchunhyang University Hospitals in Seoul and Bucheon between July 2012 and August 2013 were enrolled. The patients were diagnosed by reverse transcription-polymerase chain reaction (RT-PCR), and the clinical variables were compared according to the presence of CSF pleocytosis. RESULTS: Of the 80 patients, 54 (67.5%) and 26 (32.5%) patients had and did not have CSF pleocytosis, respectively. Forty-eight (60%) patients were male, and the median age was 63 months (range, 2 to 192 months). Seventy-six (95%), 67 (83.7%), 51 (63.7), and 2 (2.5%) patients presented with fever, headache, vomiting, and seizure, respectively. Increased CSF protein and pressure were associated with CSF pleocytosis. However, age, peripheral white blood cell count, C-reactive protein, CSF glucose, CSF/serum glucose ratio, and onset-puncture time interval were not associated with the presence of CSF pleocytosis. CONCLUSION: This study demonstrated a high proportion of non-pleocytic enteroviral meningitis in children, and identified several clinical manifestations that were associated with CSF pleocytosis. The findings of this study may help us better understand the characteristics of the disease and facilitate early diagnosis and treatment of enteroviral meningitis. During the outbreak seasons of enteroviral meningitis, the importance of continuous surveillance of enteroviruses and rapid RT-PCR testing should be emphasized.

A Case of Moyamoya Disease without Transient Ischemic Attacks

Moyamoya disease is a cerebrovascular disorder characterized by internal carotid arteries' occlusion or stenosis. Its etiology remains unknown, and it occurs more frequently in Asian countries than western countries. It can occur at any age, and approximately 50% of patients are children. Initial manifestations of moyamoya disease are very different according to age. In general, cerebral ischemic symptoms like transient ischemic attacks (TIA) are the most common manifestation of children. It is a chronic progressive disease and cause recurrent stroke, so early diagnosis and management is very important. We report a case of moyamoya disease without TIA, in a 7 years old female child presenting as unusual symptoms, such as walking difficulty and dysarthria.