Exploring two contrasting surface‐active exopolysaccharides from a single strain of Ochrobactrum utilizing different hydrocarbon substrates

During production and characterization of exopolysaccharides (EPS) of Ochrobactrum pseudintermedium C1, it was observed that an experimental change in the basic hydrocarbon type of substrate for bacterial utilization led to elicitation of different surface‐active properties in the EPS produced. In the sugar substrate, it elicited surfactant property, while in oil substrates it elicited emulsifying property, which indicated that the EPS might be different. Consequently, attention was focused on a detailed analysis of this substrate‐specific EPS. Utilizing waste sugar, edible, and mineral oil substrates, EPS produced in each situation was characterized. Besides estimating surface activity and thermostability, each substrate‐specific EPS was analyzed by Fourier‐transform infrared spectroscopy, gas chromatography‐mass spectroscopy, ¹H‐nuclear magnetic resonance, and matrix‐assisted laser desorption/ionization—time of flight mass spectroscopy to find any structural difference. The results were significantly contrasting although the similarity in molecular mass suggested a basic similarity in polysaccharide structure. Morphological differences were also evident both macroscopically and microscopically with scanning electron microscopy. As the surface‐active property of EPS was dependent on the substrate utilized, their structural differences might account for it. These diverse surface activities of EPS produced by a single bacterial strain simply by changing the nature of substrate would also augment their bioapplications. Moreover, utilization of waste and easily available substrates should make such applications convenient, ecofriendly, and cost‐worthy.     

基于稀疏表示的视网膜图像对变化检测

视网膜图像对变化检测主要研究两个不同时间点所采集到图像的变化情况。图像间的亮度差异及解剖结构与病灶的亮度相似性,使得基于逐点对比的差分方法或商方法很难准确检测变化区域。针对光照干扰问题,提出对光照具有鲁棒性的稀疏表示(SRC)变化检测方法。SRC方法先抽取参考图像局部区域块构建字典,再通过稀疏表示重构当前图像的局部背景块,最后利用背景相减获得变化区域。通过该方法,图像对的亮度差异可用稀疏表示系数自动调整,而基于块的方式可过滤掉局部光照,更有效地检测出变化区域。SRC方法与其他检测方法结合,可以增加检测结果的准确性。实验根据一对来自DRIVE数据集的小病灶仿真数据,SRC方法的AUC和mAP值分别为0.986和0.865;对一对采集自临床的大病灶数据,SRC与迭代鲁棒同态曲面拟合(IRHSF)校正结合方法的AUC和mAP值分别达到了0.989和0.969。实验结果表明,SRC方法比RPCA方法对局部光照鲁棒性更强,比基于逐点的比较差分方法更多地考虑局部邻域信息,能够更有效地检测出变化区域。     

Graphene oxide regulates cox2 in human embryonic kidney 293T cells via epigenetic mechanisms: dynamic chromosomal interactions

To extend the applications of engineered nanomaterials, such as graphene oxide (GO), it is necessary to minimize cytotoxicity. However, the mechanisms underlying this cytotoxicity are unclear. Dynamic chromosomal interactions have been used to illustrate the molecular bases of gene expression, which offers a more sensitive and cutting-edge technology to elucidate complex biological processes associated with epigenetic regulations. In this study, the role of GO-triggered chromatin interactions in the activation of cox2, a hallmark of inflammation, was investigated in normal human cells. Using chromosome conformation capture technology, we showed that GO triggers physical interactions between the downstream enhancer and the cox2 promoter in human embryonic kidney 293T (293T) via p65 and p300 complex-mediated dynamic chromatin looping, which was required for high cox2 expression. Moreover, tumor necrosis factor-α (TNF-α), located upstream of the p65 signaling pathway, contributed to the regulation of cox2 activation through dynamic chromatin architecture. Compared with pristine GO and aminated GO (GO-NH₂), poly (acrylic acid)-functionalized GO (GO-PAA) induced a weaker inflammatory response and a weaker effect on chromatin architecture. Our results mechanistically link GO-mediated chromatin interactions with the regulation of cox2 and suggest that GO derivatives may minimize toxicity in practical applications.     

融合防龋DNA疫苗pGLUA-P的构建及其细胞表达研究

目的 将变形链球菌（Streptococcus mutans)表面蛋白PAc编码A区和P区（A－P）的序列克隆到真核载体pGLU中，构建出GTF－PAc融合防龋DNA疫苗，并检测其在原核细胞和真核细胞中的表达。方法 将pCIA-P质粒中A－P片段序列与pGLU质粒连接，构建出GTF－PAc融合防龋DNA疫苗pGLUA-P。将pGLUA-P转化大肠杆菌BL21（DE3），以SDS－PAGE电泳鉴定目的蛋白GLUA－P的表达。通过脂质体将pGLUA-P转染大鼠原代肌母细胞，以免疫组织化学检测GLUA－P的表达。结果 GTF－PAc融合防龋DNA疫苗pGLUA-P经酶切分析证实携带GLU和A－P片段。pGLUA-P转化的大肠杆菌BL21（DE3）经IPTG诱导能够表达完整的融合蛋白。pGLUA-P转染的大鼠原代肌母细胞中可检测到融合蛋白的表达。结论 成功地构建了融合防龋DNA疫苗pGLUA-P，所携带的基因序列正确，能够在原核和真核细胞中表达正确的融合蛋白。     

Surface electromyography of jaw muscles and kinesiographic recordings: diagnostic accuracy for myofascial pain

The present investigations attempted to assess the diagnostic accuracy of commercially available surface electromyography (sEMG) and kinesiography (KG) devices for myofascial pain of jaw muscles. Thirty-six (n = 36) consecutive patients with a research diagnostic criteria for temporomandibular disorders (RDC/TMD) axis I diagnosis of myofascial pain and an age- and sex-matched group of 36 TMD-free asymptomatic subjects underwent sEMG and KG assessments to compare EMG parameters of the masseter and temporalis muscles as well as the jaw range of motion and the interarch freeway space. EMG data at rest were not significantly different between myofascial pain patients and asymptomatic subjects, while the latter achieved significantly higher levels of EMG activity during clenching tasks. Symmetry of muscle activity at rest and during clenching tasks, KG parameters of jaw range of motion and the measurement of the interarch vertical freeway did not differ between groups. Receiver operating characteristics curve analysis showed that, except EMG parameters during clenching tasks, all the other outcome sEMG and KG measures did not reach acceptable levels of sensitivity and specificity, with a 30·6-88·9% percentage of false-positive results. Therefore, clinicians should not use sEMG and KG devices as diagnostic tools for individual patients who might have myofascial pain in the jaw muscles. Whether intended as a stand-alone measurement or as an adjunct to making clinical decisions, such instruments do not meet the standard of reliability and validity required for such usage.     

Influence of tooth clench on the soleus H-reflex

The Hoffmann (H) reflex is elicited by electrical stimulation of a mixed nerve and is used to measure the excitability of the spindle-motoneuron synapse. Recent investigations have indicated a positive correlation between increases in bite force and H-reflex facilitation. However, these investigations did not examine the H-reflex in detail or the possible role of periodontal mechanoreceptors (PMRs) in this facilitation. The current investigation was performed to determine whether PMRs play a role in H-reflex facilitation during tooth clench (TC). The H-reflex was elicited in the soleus muscle of human subjects while bite level was maintained at rest (0 N), 40 N, 80 N and maximal TC. The front teeth that contributed to the (40 N and 80 N) bite force were then locally anaesthetised (LA), and the protocol was repeated. The current data suggest that the effect of TC on the H-reflex amplitude in the human limb muscles is variable from one subject to the next. Statistical analysis has shown that the H-reflex was significantly smaller during the rest condition than during the 80 N bite (p<0.05) in both non-LA and LA conditions. Since LA did not alter the response, our results do not support that the PMRs play a major role in the facilitation of distal muscle activity.     

氟钼酸铵对牙本质胶原分解的抑制作用

目的：评价氟钼酸铵对牙本质龋损中胶原分解的抑制作用。方法：用１０％、２．８％氟钼酸铵、２％氟化钠、去离子水分别处理４组牙本质人工龋损，然后用胰蛋白酶、胶原酶分解其胶原，通过羟脯氨酸含量测定，计算并比较各组牙本质标本胶原分解量。结果：１０％、２．８％氟钼酸铵比２％氟化钠抑制两酶分解胶原的作用强（Ｐ＜０．０１），对胶原酶的作用尤为显著（Ｐ＜０．０１）。结论：氟钼酸铵抑制蛋白分解酶（尤其胶原酶）对胶原的分解作用是它抑制牙本质龋发展的重要机制之一。     

Is bovine dentine an appropriate substitute for human dentine in erosion/abrasion tests?

Summary  The study aimed to compare the dentine wear of primary and permanent human and bovine teeth because of erosion/abrasion and evaluate if bovine dentine is an appropriate substitute for human dentine in further erosion/abrasions tests. Dentine samples from deciduous molars and human third molars as well as from calves' and cattle's lower incisors were prepared and baseline surface profiles were recorded. Each day all samples were demineralized in 1% citric acid, tooth brushed with 100 brushing strokes with toothpaste slurry and stored in artificial saliva for the rest of the day. This cycle was run for 20 days. Afterwards, new surface profiles were recorded and dentine wear was calculated by a customized computer program. Dentine wear because of erosion/abrasion was not statistically, significantly different for human third molars and cattle's lower incisors ( P  = 0·7002). The dentine wear because of erosion/abrasion of deciduous molars and calves' lower incisors was significantly different ( P  < 0·0000). No statistically significant difference in the dentine wear of human third molars and cattle's lower incisors was observed, so that the use of cattle's lower incisors as substitute for adult human teeth for further investigations in erosion/abrasion studies could be accepted.     

Histological evaluation of oral implants inserted with different surgical techniques into the trabecular bone of goats

OBJECTIVE: The aim of this study was to investigate the influence of implant surface topography and surgical technique on bone response. MATERIAL AND METHODS: For the experiment, 48 screw-designed implants were used with two different surface finishes, i.e. machined and 'blasted, etched'. The implants were inserted into the left and right medial femoral condyle of eight goats using three different surgical approaches: press-fit (implant diameter=implant bed diamete(r), undersized (implant bed diameter相似文献