[Metabolic mechanism and intervention strategy of atrial fibrillation in the elderly].

Atrial fibrillation (AF) is a cardiovascular epidemic that occurs primarily in the elderly with primary cardiovascular diseases, leading to severe consequences such as stroke and heart failure. The heart is an energy-consuming organ, which requires a high degree of metabolic flexibility to ensure a quick switch of metabolic substrates to meet its energy needs in response to physiological and pathological stimulation. Metabolism is closely related to the occurrence of AF, and AF patients manifest metabolic inflexibility, such as insulin resistance and the metabolic shift from aerobic metabolism to anaerobic glycolysis. Moreover, our research group and the others have shown that metabolic inflexibility is a crucial pathologic mechanism for AF. Energy metabolism is closely linked to the aging process and aging-related diseases, and impaired metabolic flexibility is considered as an essential driver of aging. Therefore, this review focuses on the alteration of metabolic flexibility in the elderly and reveals that impaired metabolic flexibility may be an important driver for the high prevalence of AF in the elderly, hoping to provide intervention strategies for the prevention and treatment of AF in the elderly.

[Influence of dental metallic materials on MR imaging].

Magnetic resonance imaging (MRI) technique is one of the most commonly used imaging diagnostic techniques for pate diseases at present.Metal and alloy are commonly used in dental practice. The artifacts on MRI caused by metal and alloy may result in attenuation of signal intensity, image distortion and signal loss, which severely influences imaging quality. So these materials confine the application of MRI on pate. In this paper, the influence of dental metallic materials on MRI is discussed. It expounds the generation and principals of MR artifacts, the influence of artifacts of metal dental prosthetic restoration, the effects of choosing different MR sequences and imaging weight on MRI, as well as how to prevent and diminish artifacts, to provide reference for clinical practice.

BDNF-TrkB signaling pathway is involved in pentylenetetrazole-evoked progression of epileptiform activity in hippocampal neurons in anesthetized rats.

Pentylenetetrazole (PTZ) is a widely-used convulsant used in studies of epilepsy; its subcutaneous injection generates an animal model with stable seizures. Here, we compared the ability of PTZ via the intravenous and subcutaneous routes to evoke progressive epileptiform activity in the hippocampal CA1 neurons of anesthetized rats. The involvement of the BDNF-TrkB pathway was then investigated. When PTZ was given intravenously, it induced epileptiform bursting activity at a short latency in a dose-dependent manner. However, when PTZ was given subcutaneously, it induced a slowly-developing pattern of epileptogenesis; first, generating multiple population-spike peaks, then spontaneous interictal discharge-like spike, leading to the final ictal discharge-like, highly synchronized bursting fi ring in the CA1 pyramidal layer of the hippocampus. K252a, a TrkB receptor antagonist, when given by intracerebroventricular injection, significantly reduced the probability of multiple population spike peaks induced by subcutaneous injection of PTZ, delayed the latency of spontaneous spikes, and reduced the burst frequency. Our results indicate that PTZ induces a progressive change of neuronal epileptiform activity in the hippocampus, and the BDNF-TrkB signaling pathway is mainly involved in the early phases of epileptogenesis, but not the synchronized neuronal burst activity associated with epileptic seizure in the PTZ animal model. These results provide basic insights into the changing pattern of hippocampal neuronal activity during the development of the PTZ seizure model, and establish an in vivo seizure model useful for future electrophysiological studies of epilepsy.

Eucommia ulmoides Oliv. antagonizes H2O2-induced rat osteoblastic MC3T3-E1 apoptosis by inhibiting expressions of caspases 3, 6, 7, and 9.

Eucommia ulmoides Oliv. (EuO), also known as Duzhong, native to China, has been reported to have antioxidative function, but its cellular mechanism is not fully examined yet. We investigated inhibitory effects of EuO leaf ethanol extracts on H(2)O(2)-induced apoptosis in rat osteoblastic MC3T3-E1 cells and underlying mechanisms. Locally-grown Duzhong leaves were extracted with ethanol. MC3T3-E1 cells were treated with EuO (6.25, 12.5, 25, 50, and 100 µg/ml) for 24 h, and then H(2)O(2) (800 µmol/L) for an additional 24 h. Cell survival rate, percentage of apoptosis, and expressions of caspases 3, 6, 7, and 9 were examined using 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay, microscopic analysis, Western blotting, and reverse transcription polymerase chain reaction (RT-PCR). The final EuO leaf ethanol extract powder was detected to contain caffeotannic acid at 58 mg/g and geniposide at 3.45 mg/g by high performance liquid chromatography (HPLC). EuO remarkably restrained cell oxidative damage and increased cell survival rate in a dose-dependent manner: 0 µg/ml, 0.21; 6.25 µg/ml, 0. 28; 12.5 µg/ml, 0.31; 25 µg/ml, 0.48; 50 µg/ml, 0.54; and 100 µg/ml, 0.66 (P<0.05), with the half-effective concentration being around 25 µg/ml. MTT results were confirmed by microscopic analysis. Western blotting and RT-PCR analyses showed that the expressions of caspases 3, 6, 7, and 9 were significantly decreased in the EuO-treated cells compared with the control (EuO- and H(2)O(2)-free) (P<0.05), with the half-effective concentration of EuO ranging from 12.5 to 25 µg/ml. We conclude that the ethanol-extracted EuO leaf extracts promoted the growth of MC3T3-E1 cells, and suppressed the H(2)O(2)-induced apoptosis in a rat MC3T3-E1 osteogenic cell model, likely due to the inhibition of caspases' activities. The results indicate that EuO is a potent antioxidant, which may contribute to its many cellular protective functions, including the promotion of bone growth.

[Mechanism of acupuncture anesthesia for analgesia of the operative region of thyroid gland].

OBJECTIVE: To probe into peripheral nervous mechanisms of analgesic effect of electroacupuncture (EA) at Hegu (LI 4) and Neiguan (PC 6) on cervical region. METHODS: Twenty cases of thyroid disease who wished to receive acupuncture anesthesia, were stimulated with electroacupuncture at bilateral Hegu (LI 4), Neiguan (PC 6) in continued wave, intensity of 6-8 V, frequency of 10-20 Hz. After stimulation for 40 min, the operation was made. Before EA stimulation, 10 min, 20 min and 30 min after EA stimulation, changes of the physiologi cal functions including latent period, conduction velocity, wave peak amplitude of great auricular nerve were monitored and changes of pain sense were detected. RESULTS: After EA given at Hegu (LI 4) and Neiguan (PC 6) for 10 min, 20 min and 30 min, the pain sense significantly decreased (P<0.01), the latent period of great auricular nerve was shortened, and the conduction velocity was fastened and the wave peak amplitude raised with significant changes as compared with those before EA stimulation (P<0.01). CONCLUSION: EA at Hegu (LI 4) and Neiguan (PC 6) can produce a better analgesic effect on cervical region; EA at Hegu (LI 4) and Neiguan (PC 6) induces electro-physio logic changes of the nerve innervating the cervical region, showing increase of excitability; the nerves innervating Hegu (LI 4) and Neiguan (PC 6) and the nerves of cervical region possibly are homologous nerves.