Puerarin blocks Na~+ current in rat ventricular myocytes

AIM: To study the effect of puerarin (Pue) on Na~+ channel in rat ventricular myocytes. METHODS: Whole-cell patch-clamp technique was applied on isolated cardiomyocytes from rats. RESULTS: Pue inhibited cardiac I_(Na) in a positive rate-dependent and dose-dependent manner, with an IC_(50) of 349 μmol/L. The kinetics of blockage of cardiac sodium channel by Pue resembled the ClassIa/Ic of antiarrhythmic agents. Pue 300 μmol/L did not alter the shape of the I-V curve of I_(Na), but markedly shifted the steady-state inactivation curve of I_(Na) towards more negative potential by 15.9 mV, and postponed the recovery of I_(Na) inactivation state from (21.9±1.6) ms to (54.4±3.4) ms (P<0.01 ). It demonstrated that the steady state of inactivation was affected by Pue significantly. CONCLUSION: Pue protected ventricular myocytes against cardiac damage and arrhythmias by inhibiting recovery from inactivation of cardiac Na~+ channels.     

乳癌手术麻醉方法的临床分析

目的对3种乳癌手术麻醉方法进行比较,以选择合理的麻醉方法。方法对800例乳癌手术病人的三种麻醉的方法、麻醉选择、麻醉并发症、麻醉注意事项等进行了分析总结。结果硬膜外阻滞麻醉(EPA)穿刺成功226例(98.15%),阻滞效果满意208例(90.04%),出现轻度并发症4例;静脉吸入复合麻醉(VICA)气管插管成功率100%,95例(20.43%)气管内插管时心血管反应较显著;全身静脉麻醉(TIA)94例(90.38%)心血管反应较显著,62例(59.62%)术中舌根后坠需置咽喉通气道或托起下颌维持呼吸道通畅。结论EPA、VICA发生并发症少于TIA,乳癌手术麻醉应选择EPA、VICA,TIA慎用。     

Bone width is correlated positively with the upper to the lower segment ratio in elderly men--the MINOS study

Before puberty, limbs grow more rapidly than the spine. During puberty, lengthening of the spine and increase in bone width accelerate. Correlation of parameters with lengths of the upper and lower segments and with the upper/lower segment ratio may indicate the period of growth critical for their determination. We assessed the association of bone mineral and width with the upper/lower segment ratio in 542 elderly men from the MINOS cohort. Areal bone mineral density (aBMD) was measured at the lumbar spine and right hip using pencil-beam dual-energy X-ray absorptiometry and at the distal forearm using single energy X-ray absorptiometry. Upper/lower segment ratio correlated positively with bone mineral content (BMC), aBMD and width of third lumbar vertebra (L3), femoral neck and distal radius. Men in the highest quartile of the upper/lower segment ratio had larger bones by 2.5 to 5.0% (0.3-0.4 SD, p<0.02-0.002) compared with the lowest quartile. Bone width correlated more strongly with the upper segment length than with that of the lower one. Volumetric BMD (vBMD) did not correlate with the upper/lower segment ratio nor with the lengths of the body segments. At the femoral neck and distal radius, men in the highest quartile of the upper/lower segment ratio had higher estimated cortical thickness (5.3%, 0.41 SD, p<0.01 and 4.0%, 0.31 SD, p<0.03), bigger cortical area (8.0%, 0.54 SD and 6.8%, 0.52 SD, p<0.0001) and higher estimated bending strength (9.3 to 13.3%, 0.46 to 0.54 SD, p<0.0001). Elderly men with the higher upper/lower segment ratio had higher BMC and bending strength because they had wider bones, not higher vBMD. The bone size correlated positively with the length of the upper segment, not negatively with that of the lower segment. Our data may suggest an important role of pubertal growth for both bone width and strength in men but do not establish the determinants of this association. Given methodological limitations, these results need to be confirmed in a younger and more representative group of men.     

Evolution of microbial community diversity and enzymatic activity during composting

The composting of organic material is dependent on microbial activity. However, the dynamics of the microbial community during the composting process remain obscure. Here, denaturing gradient gel electrophoresis of 16S rDNA amplicons in a chicken manure-based compost was applied to characterize the components of the microbial community during the composting process. In addition, the activity of key microbial enzymes was monitored. Arcobacter spp. and Marinospirillum spp. were the dominant species prior to composting, whereas Thermotogae spp. became more strongly represented as the composting process proceeded. Bacillus and Cohnella spp. were featured at various phases. Correlation analysis showed that the diversity of the microbial community was positively correlated with the compost pH, its total nitrogen level, its carbon-to-nitrogen ratio and the activity of protease, and negatively correlated with its organic carbon content and seed germination indices.     

Involvements of mu- and kappa-opioid receptors in morphine-induced antinociception in the nucleus accumbens of rats

It is well known that there are three types of opioid receptors, mu- (MOR), delta- (DOR), and kappa-opioid receptor (KOR) in the central nervous system. The present study investigated the involvement of opioid receptors in morphine-induced antinociception in the nucleus accumbens (NAc) of rats. The hindpaw withdrawal latencies to thermal and mechanical stimulation increased markedly after intra-NAc administration of morphine. The antinociceptive effects induced by morphine were dose-dependently inhibited by intra-NAc administration of the non-selective opioid receptor antagonist naloxone. Furthermore, the morphine-induced antinociception was significantly attenuated by subsequent intra-NAc injection of the MOR antagonist beta-funaltrexamine or the KOR antagonist nor-binaltorphimine, but not the DOR antagonist naltrindole. The results indicate that MOR and KOR, but not DOR are involved in the morphine-induced antinociception in the NAc of rats.     

Magnesium hydroxide temporarily enhancing osteoblast activity and decreasing the osteoclast number in peri-implant bone remodelling

Repeated observations of enhanced bone growth around various degradable magnesium alloys in vivo raise the question: what is the major mutual origin of this biological stimulus? Several possible origins, e.g. the metal surface properties, electrochemical interactions and biological effects of alloying elements, can be excluded by investigating the sole bone response to the purified major corrosion product of all magnesium alloys, magnesium hydroxide (Mg(OH)₂). Isostatically compressed cylinders of pure Mg(OH)₂ were implanted into rabbit femur condyles for 2–6 weeks. We observed a temporarily increased bone volume (BV/TV) in the vicinity of Mg(OH)₂ at 4 weeks that returned to a level that was equal to the control at 6 weeks. The osteoclast surface (OcS/BS) was significantly reduced during the first four weeks around the Mg(OH)₂ cylinder, while an increase in osteoid surface (OS/BS) was observed at the same time. At 6 weeks, the OcS/BS adjacent to the Mg(OH)₂ cylinder was back within the same range of the control. The mineral apposition rate (MAR) was extensively enhanced until 4 weeks in the Mg(OH)₂ group before matching the control. Thus, the enhanced bone formation and temporarily decreased bone resorption resulted in a higher bone mass around the slowly dissolving Mg(OH)₂ cylinder. These data support the hypothesis that the major corrosion product Mg(OH)₂ from any magnesium alloy is the major origin of the observed enhanced bone growth in vivo. Further studies have to evaluate if the enhanced bone growth is mainly due to the local magnesium ion concentration or the local alkalosis accompanying the Mg(OH)₂ dissolution.     

纳米银的抗菌特性及其在医学中的应用

纳米银是利用现代纳米技术制造的新一代抗菌材料,因其具有优异的抗菌杀菌活性及在伤口修复方面的积极作用,在医学生物学领域获得了广泛应用.目前已有一些纳米银产品应用于临床,如纳米银抗菌凝胶、纳米银敷料、纳米银心血管支架、纳米银导管、纳米银骨水泥等.近年来的研究表明,纳米银的长效、广谱、强效的抗菌活性源于其对微生物复杂而特异的抗菌机制.尽管纳米银不会使病菌产生耐药性,是人们期望中的理想抗菌材料,但研究人员对其毒性机制依然不甚了解.本文就纳米银的合成、抗菌机制、毒性及在医学中的应用做了简要总结和展望.     

微孔过滤实验中红细胞变形性的表达

在用微孔过滤法测定红细胞变形性的实验中,为了便于定量地评定和比较红细胞变形性,我们对目前常用的表达变形性的各种物理参数和人为定义的指标的确切含义和适用性进行了较为全面的分析和讨论。认为红细胞平均过孔时间(或相对过孔阻力）和堵孔红细胞比例分别用于表达红细胞平均变形性和堵孔特性比较合适。早期研究力求避免过滤过程中红细胞堵塞膜孔现象对实验的干扰,但通过对近年来不同实验方法下实验结果的分析,发现红细胞堵孔特性蕴涵着重要信息,反映了红细胞变形性的不同方面。表达这一特性的参数对一些物理、化学,尤其是病理因素引起的变形性改变,比平均变形性参数更敏感。