Critical Differences in Magnitude and Duration of N-methyl-D-aspartate (NMDA) Receptor Activation between Long-term Potentiation (LTP) and Long-term Depression (LTD) Induction

The induction of both long-term potentiation (LTP) and long-term depression (LTD) in the hippocampal CA1 region is triggered by the activation of N-methyl-D-aspartate (NMDA) receptors and the subsequent postsynaptic intracellular Ca2+ increase. However, how NMDA receptor activation differs between LTP and LTD induction is unclear. In the present study, we examined the eff ects of the magnitude and duration of NMDA receptor activation on the induction of LTP and LTD. Partial blockage of NMDA receptors by a low concentration of aminophosphonovaleric acid (APV)(2 &#956;M) prevented the induction of LTP, but not LTD. In contrast, a high concentration of APV(25 &#956;M) blocked both LTP and LTD. Tetanus stimulation-induced LTP was impaired when hippocampal slices were given the tetanus stimulation for more than 5 min. Under partial blockage of NMDA receptors, the prolonged-tetanus stimulation induced LTD but not LTP. This phenomenon was mimicked by the application of glutamate to the slices. Finally, LTD induced by prolonged activation of NMDA receptors was not aff ected by inhibition of the desensitization of &#945;-amino-3-hydroxy-5 methylisoxazole-4-propionic acid (AMPA) receptors. These results suggest that critical diff erences exist between the induction of LTP and that of LTD in terms of both the magnitude and the duration of NMDA receptor activation. The duration of the increase in intracellular Ca2+ concentration may be critical for determining whether LTP or LTD induction occurs.</p

Correlation between inflammation state and successful medical cardioversion using bepridil for refractory atrial fibrillation

AbstractBackgroundIt has been reported that inflammation is associated with long-term maintenance of sinus rhythm after electrical cardioversion for non-valvular atrial fibrillation (AF). However, the relation between high-sensitive C-reactive protein (hs-CRP) and the recurrence of AF after medical cardioversion is unknown. On the other hand, bepridil is very effective in restoring sinus rhythm for patients with refractory AF.Methods and resultsIn 119 patients with non-valvular AF lasting >6 months who failed to maintain sinus rhythm after medical cardioversion without bepridil or electrical cardioversion, we prescribed bepridil. We divided our patients into success group who maintained sinus rhythm for at least 6 months using bepridil and failure group, and compared the following parameters, which were measured just before prescription of bepridil, between the two groups: hs-CRP as a marker of inflammation, left ventricular end-diastolic dimension, ejection fraction, and left atrial dimension as echocardiographic markers, and the incidence of dyslipidemia, hypertension, and diabetes mellitus. After the treatment with bepridil, 57 patients converted to sinus rhythm; however, 12 patients among these 57 patients could not maintain sinus rhythm. Therefore, the success group consisted of 45 patients (38%). Univariate analysis revealed that left atrial dimension and the value of hs-CRP were significantly lower and ejection fraction was significantly higher in the success group than the failure group. Multivariate analysis showed that hs-CRP and left atrial dimension were independent factors for AF recurrence.ConclusionsBepridil is effective in restoring sinus rhythm for refractory AF patients. Inflammation, in addition to left atrial dimension, may be associated with successful cardioversion using bepridil

Osteomyelitis of the Mandible Caused by Late Fracture following Third Molar Extraction

The common postoperative complications of the extraction of third molars are frequently reported; however, reports about osteomyelitis of the mandible caused by late fracture following third molar extraction are rare. Here, we report a case of osteomyelitis of the mandible caused by late fracture following third molar extraction. A 38-year-old Japanese man was referred to the surgery department with chief complaints of dull pain and swelling in the right masseteric region and paresthesia of his lower lip and mental region in March 2018. A family dentist removed his lower third molar in the right side in January 2018. When the patient was chewing an innards stew 23 days after the procedure, he heard a cracking sound from the right mandible. Thus, we diagnosed the patient as having osteomyelitis of the mandible caused by late fracture following third molar extraction and performed sequestrectomy and curettage under general anesthesia in April 2018. In conclusion, it is necessary to recognize the possibility that late fracture following third molar extraction can cause osteomyelitis. Furthermore, once osteomyelitis of the mandible caused by late fracture occurred, early and appropriate treatment is necessary because the osteomyelitis may progress rapidly and in some cases may result in pathological fracture