蒙药材黄花铁线莲抗肿瘤活性成分研究

目的:研究黄花铁线莲Clematis intricata干燥带花枝条中的抗肿瘤活性成分。方法:采用海虾幼虫致死实验为抗肿瘤活性追踪测试模型,硅胶、SephadexLH-20和制备型HPLC等色谱手段进行分离纯化,根据波谱数据结合理化性质鉴定化合物结构。结果:分离鉴定了7个黄酮,分别为芹菜素(1)、木犀草素-3’-O-β-D-吡喃葡萄糖苷(2)、槲皮素-3-O-β-D-吡喃葡萄糖苷(3)、芦丁(4)、山奈酚-3-O-α-L-吡喃鼠李糖基(1→6)-β-D-吡喃葡萄糖苷(5)、芹菜素-7-O-(6″-E-p-香豆酰基)-β-D-葡萄糖苷(6)、芹菜素-6-C-(6″-E-p-香豆酰基)-β-D-葡萄糖苷(7)。结论:7个化合物均为首次从该植物中分离得到。     

New methodology for evaluating osteoclastic activity induced by orthodontic load

Orthodontic tooth movement (OTM) is a dynamic process of bone modeling involving osteoclast-driven resorption on the compression side. Consequently, to estimate the influence of various situations on tooth movement, experimental studies need to analyze this cell.

Objectives

The aim of this study was to test and validate a new method for evaluating osteoclastic activity stimulated by mechanical loading based on the fractal analysis of the periodontal ligament (PDL)-bone interface.

Material and Methods

The mandibular right first molars of 14 rabbits were tipped mesially by a coil spring exerting a constant force of 85 cN. To evaluate the actual influence of osteoclasts on fractal dimension of bone surface, alendronate (3 mg/Kg) was injected weekly in seven of those rabbits. After 21 days, the animals were killed and their jaws were processed for histological evaluation. Osteoclast counts and fractal analysis (by the box counting method) of the PDL-bone interface were performed in histological sections of the right and left sides of the mandible.

Results

An increase in the number of osteoclasts and in fractal dimension after OTM only happened when alendronate was not administered. Strong correlation was found between the number of osteoclasts and fractal dimension.

Conclusions

Our results suggest that osteoclastic activity leads to an increase in bone surface irregularity, which can be quantified by its fractal dimension. This makes fractal analysis by the box counting method a potential tool for the assessment of osteoclastic activity on bone surfaces in microscopic examination.     

Volume management in critically ill patients: New insights

In order to turn a fluid challenge into a significant increase in stroke volume and cardiac output, 2 conditions must be met: 1) fluid infusion has to significantly increase cardiac preload and 2) the increase in cardiac preload has to induce a significant increase in stroke volume. In other words, a patient can be nonresponder to a fluid challenge because preload does not increase during fluid infusion or/and because the heart (more precisely, at least 1 of the ventricles) is operating on the flat portion of the Frank-Starling curve. Volumetric markers of cardiac preload are therefore useful for checking whether cardiac preload effectively increases during fluid infusion. If this is not the case, giving more fluid, using a venoconstricting agent (to avoid venous pooling), or reducing the intrathoracic pressure (to facilitate the increase in intrathoracic blood volume) may be useful for achieving increased cardiac preload. Arterial pulse pressure variation is useful for determining whether stroke volume can/will increase when preload does increase. If this is not the case, only an inotropic drug can improve cardiac output. Therefore, the best option for determining the usefulness of, and monitoring fluid therapy in critically ill patients is the combination of information provided by the static indicators of cardiac preload and arterial pulse pressure variation.