AMPK在妊娠期糖尿病发病机制中的作用

腺苷酸活化蛋白激酶是一种重要的蛋白激酶,主要作用是协调代谢和能量平衡.腺苷酸活化蛋白激酶被激活后,在增加骨骼肌对葡萄糖摄取、增强胰岛素敏感性、增加脂肪酸氧化以及调节基因转录等方面发挥重要作用.已经证实脂联素有调节糖脂代谢的作用,但其作用机制尚不十分清楚,很可能是通过腺苷酸活化蛋白激酶介导,对脂联素信号转导通路的研究将成为进一步理解脂联素作用的关键所在.而脂联素又是妊娠期糖尿病的预测因子,所以腺苷酸活化蛋白激酶逐渐成为对妊娠期糖尿病研究中的焦点.     

Alkaline phosphatase production by periosteal cells at various oxygen tensions in vitro

A mammalian periosteal cell culture system was developed to investigate the metabolic response of fresh calf bone periosteal cells to various oxygen tensions in vitro. Two predominant cell phenotypes were seen in the culture system. A rapidly proliferating mat of alkaline phosphatase-negative cells supported the growth of overlying clusters of alkaline phosphatase-positive cells. The appearance and subsequent population growth of the alkaline phosphatase-positive cells correlated directly with increases in enzyme activity on biochemical assay. Alkaline phosphatase production was optimal at lower oxygen tensions (5%, 9%), which approximated capillary pO2. In addition, the preconfluence oxygen environment was more critical to the final expression of the enzyme activity than the postconfluence environment. The mechanism of the environmental regulation of alkaline phosphatase gene expression at various oxygen tensions is not known. Periosteal cells were highly sensitive to oxygen tension and expressed alkaline phosphatase enzyme activity at oxygen levels approximating capillary rather than atmospheric pO2.     

臂丛神经根性损伤膈神经移位术对青壮年患者早期呼吸功能的影响

目的研究臂丛神经损伤膈神经移位术对青壮年患者早期呼吸功能的影响.方法对16例接受膈神经移位治疗的患者,在术前、术后（10 d）进行肺功能指标的比较,同时定期进行门诊随访,观察呼吸系统自觉症状程度.结果13例术后出现了不同程度的供氧不足症状,16例全部出现一侧膈肌抬高,术后第10天肺活量（VC）、肺活量预计值百分数（VC%）分别比术前减少37.98%和26.88%,两者差异有统计学意义（tvc=11.532、tvc%=0,P＜0.01）.其它项目如残气量（RV）较术前轻度下降,肺总量（TLC）下降值达到术前肺总量的36.49%,残气量/肺总量比值（RV/TLC%）较术前上升了4.75%,上述各指标的差值均有统计学意义.1 s用力呼气量/用力肺活量比值（FEV1/FVC）和术前比基本无改变,但其差值有统计学意义.膈神经移位右侧（10例）与左侧（6例）术前、术后肺活量比较差异有统计学意义.术后随访8个月～2年,所有患者均无明显呼吸困难和胸闷等症状.结论膈神经移位术后对青壮年患者肺容量有较大的丧失,肺通气功能减弱和小气道阻力增加,但其丧失程度在机体自身代偿耐受范围内,不会导致急剧发生的严重呼吸功能障碍.建议对右侧臂丛神经根性损伤的患者,术前进行严格的肺、心功能检查,避免发生较为严重的并发症.     

Capacitively coupled electrical stimulation of bovine growth plate chondrocytes grown in pellet form

Pellets formed from isolated bovine growth plate chondrocytes were grown in various capacitively coupled electrical fields. The signals chosen were 0, 10, 100, 250, 500, 750, 1,000, and 1,500 V peak-to-peak, 60 kHz. The effect on cell proliferation and matrix production of these different voltages was determined by [3H]thymidine and [35S]sulfate uptake, respectively, Cyclic AMP assays were done to determine if increases in either thymidine or sulfate uptake were associated with changes in cAMP levels. Significantly increased cell proliferation occurred at 500, 750, and 1,000 V peak to peak. The calculated electric fields were 1.5 to 3.0 x 10(-2) V/cm. Proliferation was significantly inhibited at 1,500 V peak-to-peak with a calculated field of 4.5 x 10(-2) V/cm. Little if any change was seen in cAMP levels at 30 or 60 min following application of the appropriate electric signals.     

In vitro bone-cell response to a capacitively coupled electrical field. The role of field strength, pulse pattern, and duty cycle.

Newborn rat calvarial bone cells were grown to confluence and subjected to a matrix of sine wave 60-kHz capacitively coupled electrical signals of various field strengths, pulse-burst patterns, and duty cycles. Both [3H] thymidine incorporation into DNA and alkaline phosphatase activity were evaluated in field strengths ranging from 0.0001 to 20 mV/cm, with pulse-burst patterns ranging from continuous to 5 milliseconds ON/495 milliseconds OFF, with daily duty cycles ranging from 0.25% to 25%. A significant increase in proliferation occurred in field strengths of 0.1, 1, and 20 mV/cm when the signal was applied continuously for six hours. Significant proliferation also occurred when the 20-mV/cm field was pulsed for six hours at 5 milliseconds ON/495 milliseconds OFF and at 5 milliseconds ON/245 milliseconds OFF. No change in alkaline phosphatase activity occurred in the 20-mV/cm field with any signal. At 1 mV/cm, there was a significant decrease in alkaline phosphatase activity in the continuous signal and in the 5 milliseconds ON/62 milliseconds OFF signal; in the lower fields evaluated, there was an actual decrease in alkaline phosphatase activity with some of the signals. The field strength plays a dominant role in determining the bone-cell's proliferative response, and to a lesser extent the alkaline phosphatase activity response, to a capacitively coupled electric field. The pulse configuration and the duty cycle are also important, but only if the proper field strength is being applied to the cell.     

Pulsing electromagnetic field stimulation of the in vitro growth plate

Specific pulsing electromagnetic fields (PEMFs) have been used to stimulate growth and repair of osteogenic tissues; however, the basis for this specificity is unknown. Previously, we determined the relevant electromagnetic field parameters of the clinically used PEMF and independently verified the beneficial effects of PEMFs on the rabbit fibula fracture healing model. The goal of the present study was to develop an in vitro model that would permit the effectiveness of various electric and magnetic field components of the PEMF to be determined. The costochondral junction (CCJ) of the 21-day-old rat was exposed in vitro to PEMFs with various electric and magnetic field component amplitudes. Response of this model to PEMFs was determined by nondestructive macrophotographic measurement of CCJ growth. Preliminary data indicated that temperature effects were present in this in vitro system. Subsequent experiments designed to separate the effects of temperature and PEMFs on the growth of CCJs in tissue culture were performed. Results indicate that accurate and frequent temperature measurements must be made for in vitro models being used to study effects of PEMFs. Small temperature differences induced by the coils used to produce PEMFs in the CCJ experimental system can have significant stimulatory effects, and the combined effects of temperature and PEMFs are not linearly additive in this model. Furthermore, our results suggest that thermal and PEMF stimuli could affect macrophotographically measured growth of the CCJ by separate mechanisms or could have a synergistic effect. Therefore, PEMF stimulation experiments should be performed under strictly "athermal" conditions.     

An Analytic Model of Subminiature Auditory Sensation System for Sound Source Localization

It is reported that some types of insects have a remarkable ability to detect the direction of an incident sound even though its acoustic sensory organs are in very close proximity each other. Maybe the ears are jointed by a cuticular structure with which the separated motions can be coupled mechanically and thus be magnified. In this paper, a detailed model is setup to describe the principle of this type of localization using a mechanical coupled structure. The transfer functions and the responses of the model in terms of time and frequency are analyzed to describe the mechanism of its ability of directional hearing. This analytical model provides a method to design the experimental model for the predetermined incident sound pressure, and the analysis of this model shows that this structure have the ability to determine the direction of the incident stimulus.