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.     

Canine myocardial reperfusion injury: protection by a free radical scavenger, N-2-mercaptopropionyl glycine

Oxygen-derived free radicals and their metabolites may contribute to the extension of irreversible cellular injury, which occurs on reperfusion of the previously ischemic myocardium. Therefore, therapy directed against the toxic effects of reactive oxygen species may provide protection to the ischemic myocardium, which undergoes subsequent reperfusion. We evaluated the effectiveness of N-2-mercaptopropionyl glycine (MPG), a free radical scavenger, to limit the extent of irreversible injury resulting from 90 min of ischemia followed by 6 h of reperfusion in a canine model of myocardial infarction. In three groups of dogs, MPG (20 mg/kg) was administered as a constant infusion into the left atrium. Group I received MPG for 2 h, starting 15 min before occlusion of the left circumflex coronary artery and ending 15 min after reperfusion. Group II received MPG for 1 h, starting 15 min before reperfusion. Group III received MPG for 1 h beginning 45 min after reperfusion. Each group was compared with its respective saline control group. Infarct size was reduced by 35% in Group I (32.2 +/- 5.1% vs. 47.7 +/- 3.4% of the area at risk, p less than 0.05) and Group II (31.4 +/- 3.6% vs. 47.5 +/- 5.1% of the area at risk, p less than 0.025) in comparison with the saline treated control animals. In contrast, in Group III infarct size did not differ significantly from the saline-treated control group (45.9 +/- 3.3% vs. 47.7 +/- 3.5% of the area at risk). The percent of left ventricle at risk did not differ among the groups. The beneficial effects of MPG could not be explained on the basis of hemodynamic differences. In addition, MPG did not influence regional myocardial blood flow. In vitro studies indicated that MPG effectively scavanges O2- generated by the hypoxanthine-xanthine oxidase reaction, as well as by PMA-activated polymorphonuclear leukocytes. Based on these observations, we propose that MPG exerts its beneficial effects by protecting against free radical-mediated damage during the early phase of reperfusion.     

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.     

A ubiquitous protein is the source of naturally occurring peptides that are recognized by a CD8+ T-cell clone.

We previously isolated from mouse spleen an octapeptide (LSPFPFDL) that in association with the class I major histocompatibility complex protein Ld is recognized by the antigen-specific receptor of an alloreactive CD8+ T-cell clone (2C). Guided by an assay dependent upon the same 2C T-cell receptor, we have now isolated from the same source another naturally occurring peptide. The second peptide (VAITRIEQLSPFPFDL) includes the entire octapeptide sequence and preliminary evidence suggests that it may be a natural precursor of the octapeptide. On finding extensive sequence homology between the 16-mer and part of human 2-oxoglutarate dehydrogenase, we determined the cDNA sequence of mouse 2-oxoglutarate dehydrogenase and found that the deduced amino acid sequence matches precisely the two naturally occurring peptides, indicating their origin by cellular processing of this ubiquitous self protein.     

Transsynaptic degeneration of motoneurones caudal to spinal cord lesions

We studied the effects of complete transversal section of the spinal cord, at T8-10, in adult rats, upon the number and morphology of identified motoneurones in lumbar segments L4 and L5. In observations by light and electron microscopy many lumbar motoneurones had structural abnormalities when the interval between surgery and perfusion ranged between a few hours and one week. We found also that as many as 25% of the motoneurones distal to a cord transection disappeared as a consequence of the lesions. We did not find comparable changes in the spinal cord at C6 after transection at T8-10. Complete removal of the cerebellum did not reduce the lumbar motoneurone counts. Bilateral ablation of the "motor" cortex did cause a reduction of motoneurone counts at L4-5; these animals showed normal or near normal spontaneous locomotor activity beginning a few days after the lesion was placed. Motoneurone counts were significantly reduced after partial cord lesions that spared the dorsal funiculi (where the corticospinal tract travels in the rat), but in this case the rats were paraplegic as a result of the lesion. Cord transection at 7 days of postnatal age resulted in reduced motoneurone counts when the rats reached adulthood. Intraspinal or subarachnoid administration of colchicine led to reduced motoneurone counts. Prolonged infusion of a GABA agonist, muscimol, into the lumbar CSF did not prevent the loss of motoneurones produced by cord transection. Pretreatment of animals with a Ca2+ channel blocker (nimodipine) did not prevent the effects of cord transection.(ABSTRACT TRUNCATED AT 250 WORDS)     

Decrease of potassium permeability by intracellular application of sodium ions in snail neurons

In the identified neurons B1, B2 and B3 of Helix pomatia an intracellular injection of Na+ induced an outward current in 10% and an inward current in 90% of the experiments. The outward current was associated with an increase and the inward current with a decrease of the membrane conductance. Both currents reversed at membrane potentials of between -60 and -70 mV. Inward currents were also elicited by intracellular Li+ or tris-[hydroxymethyl]-aminomethane (Tris+) injection. All inward currents were reduced by extracellular administration of tetraethylammonium or quinine. It is suggested that the outward current represents a calcium-activated potassium current and that the inward current is due to a blockade of potassium channels from the intracellular side.     

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.