Variation in cownose ray Rhinoptera neglecta abundance and group size on the central east coast of Australia

Here, we provide baseline information about the relative abundance and group size of the Australian cownose ray Rhinoptera neglecta on the central east coast of Australia. Using drone monitoring over 2 years, we completed 293 transects, each 2 km in length, at four locations distributed along c.100 km of coast. In total, 5979 R. neglecta were observed with overall relative abundance (±SE) of, 20.4 (±3.3) individuals per transect. The numbers of R. neglecta varied among locations, with the highest density found off the beach adjacent to the river mouth at Evans Head. The number of rays observed also decreased with increasing wind speed. While some of this relationship was probably associated with visibility, R. neglecta may also move offshore during strong winds. We found no evidence that R. neglecta was under significant threat. Additionally, our cost-effective surveys demonstrate the utility of aerial drones in fisheries conservation biology.     

Near-infrared photons: a non-invasive probe for studying bone blood flow regulation in humans

The study of bone blood flow regulation in humans has always represented a difficult task for the clinician and the researcher. Classical measurement techniques imply the presence of ionizing radiation or contrast agents, or they are slow or cannot be repeated too often in time. In the present review, we would like to give a perspective on how the optical approach might overcome some of these problems and give unique solutions to the study of bone blood flow regulation. We hope that the present contribution will encourage the scientific community to put a greater attention on this approach.     

脑血疏口服液与大骨瓣减压硬膜扩大减张缝合术治疗大面积脑梗死的疗效及对血清NSE和hs-CRP水平的影响

目的:探讨脑血疏口服液配合大骨瓣减压硬膜扩大减张缝合术对大面积脑梗死患者的临床疗效及对血清超敏C反应蛋白(hs-CRP)及神经元特异性烯醇化酶(NSE)水平的影响。方法:选取2013年1月~2015年1月我院收治的大面积脑梗死患者87例,采用随机单盲取法分为试验组44例,对照组43例。两组患者均给予标准大骨瓣减压硬膜扩张缝合术治疗,对照组术后给予常规及对症治疗,试验组在对照组基础上给予脑血舒口服液治疗。观察两组患者治疗前后hs-CRP、NSE水平变化,同时进行日常生活活动能力量表(ADL)评分、神经功能缺损量表(NIHSS)评分及生活质量指数(BI)测定,并评定和比较治疗效果。结果:治疗1疗程后,试验组总有效率为97.73%,显著高于对照组81.40%(P0.05)。两组血清hs-CRP、NSE水平ADL、NIHSS评分均显著低于治疗前(P0.05),BI指数明显高于治疗前,且试验组血清hs-CRP、NSE水平ADL、NIHSS评分明显低于对照组(P0.05),BI指数明显高于对照组(P0.05)。两组治疗期间均未见严重不良反应。结论:脑血舒口服液配合大骨瓣减压硬膜扩大减张缝合术治疗大面积脑梗死患者可有效提高临床疗效,且安全性高,可能与其降低血清NSE、hs-CRP水平有关。     

火球菌Pyrococcus furious瓣状核酸内切酶1的表达纯化及酶学特征

【目的】克隆表达和纯化火球菌Pyrococcus furious来源的瓣状核酸内切酶1基因pFEN1(PF1414),对该蛋白的活性和酶学特征进行鉴定和分析。【方法】将pFEN1在大肠杆菌中进行重组表达,经亲和层析纯化得到电泳纯蛋白;利用人工合成的荧光标记的寡核苷酸片段作为底物,用变性聚丙烯酰胺凝胶电泳鉴定pFEN1在体外的酶学特性以及与其他蛋白的相互作用。【结果】pFEN1重组蛋白能在大肠杆菌中进行高效表达;高于100 mmol/L的NaCl会抑制pFEN1的活性;pFEN1的核酸酶活性依赖于金属离子Mg~(2+)或Mn~(2+),且Mn~(2+)的催化效率优于Mg~(2+);来自嗜热古菌的pFEN1是一种耐高温蛋白,最适反应温度为60–65°C;增殖细胞核抗原(PCNA)能促进pFEN1的内切酶活性。【结论】本研究证实pFEN1是一种Mg~(2+)或Mn~(2+)依赖的核酸内切酶,且PCNA能促进该酶的活性。     

A conserved tyrosine residue aids ternary complex formation,but not catalysis,in phage T5 flap endonuclease

The flap endonucleases, or 5' nucleases, are involved in DNA replication and repair. They possess both 5'-3' exonucleolytic activity and the ability to cleave bifurcated, or branched DNA, in an endonucleolytic, structure-specific manner. These enzymes share a great degree of structural and sequence similarity. Conserved acidic amino acids, whose primary role appears to be chelation of essential divalent cation cofactors, lie at the base of the active site. A loop, or helical archway, is located above the active site. A conserved tyrosine residue lies at the base of the archway in phage T5 flap endonuclease. This residue is conserved in the structures of all flap endonucleases analysed to date. We mutated the tyrosine 82 codon in the cloned T5 5' nuclease to one encoding phenylalanine. Detailed analysis of the purified Y82F protein revealed only a modest (3.5-fold) decrease in binding affinity for DNA compared with wild-type in the absence of cofactor. The modified nuclease retains both structure-specific endonuclease and exonuclease activities. Kinetic analysis was performed using a newly developed single-cleavage assay based on hydrolysis of a fluorescently labelled oligonucleotide substrate. Substrate and products were resolved by denaturing HPLC. Steady-state kinetic analysis revealed that loss of the tyrosine hydroxyl function did not significantly impair k(cat). Pre-steady state analysis under single-turnover conditions also demonstrated little change in the rate of reaction compared to the wild-type protein. The pH dependence of the kinetic parameters for the Y82F enzyme-catalysed reaction was bell-shaped as for the wild-type protein. Thus, Y82 does not play a role in catalysis. However, steady-state analysis did detect a large (approximately 300-fold) defect in K(M). These results imply that this conserved tyrosine plays a key role in ternary complex formation (protein-DNA-metal ion), a prerequisite for catalysis.     

The acetylatable lysines of human Fen1 are important for endo- and exonuclease activities

Human Fen1 can be acetylated in vivo and in vitro resulting in reduced endonuclease and exonuclease activities in vitro. Acetylation occurs at four lysines located at the C terminus of Fen1, which is important for DNA binding. In this paper we show that Fen1 mutant proteins lacking the lysines at the C terminus have both reduced PCNA independent exonucleolytic and endonucleolytic activities. However, lysines at the C terminus are not required for PCNA stimulation of human Fen1. A double flap substrate was optimal for human Fen1 endonuclease and did not require the C-terminal lysines. Similarly, a one nucleotide 3'-overhang nick substrate was optimal for human Fen1 exonuclease and also did not require the C-terminal lysines. Finally, we found by an electromobility shift assay that human Fen1 had a different mode of binding with a double flap substrate containing a one nucleotide 3'-tail when compared to various other flap substrates. Taken together, our results confirm the double flap substrate as the likely in vivo intermediate for human Fen1 and that the C-terminal lysines are important for the endonuclease and exonuclease activities likely through DNA binding.     

Glycolysis-mediated control of blood-brain barrier development and function

The blood-brain barrier (BBB) consists of differentiated cells integrating in one ensemble to control transport processes between the central nervous system (CNS) and peripheral blood. Molecular organization of BBB affects the extracellular content and cell metabolism in the CNS. Developmental aspects of BBB attract much attention in recent years, and barriergenesis is currently recognized as a very important and complex mechanism of CNS development and maturation. Metabolic control of angiogenesis/barriergenesis may be provided by glucose utilization within the neurovascular unit (NVU). The role of glycolysis in the brain has been reconsidered recently, and it is recognized now not only as a process active in hypoxic conditions, but also as a mechanism affecting signal transduction, synaptic activity, and brain development. There is growing evidence that glycolysis-derived metabolites, particularly, lactate, affect barriergenesis and functioning of BBB. In the brain, lactate produced in astrocytes or endothelial cells can be transported to the extracellular space via monocarboxylate transporters (MCTs), and may act on the adjoining cells via specific lactate receptors. Astrocytes are one of the major sources of lactate production in the brain and significantly contribute to the regulation of BBB development and functioning. Active glycolysis in astrocytes is required for effective support of neuronal activity and angiogenesis, while endothelial cells regulate bioavailability of lactate for brain cells adjusting its bidirectional transport through the BBB. In this article, we review the current knowledge with regard to energy production in endothelial and astroglial cells within the NVU. In addition, we describe lactate-driven mechanisms and action of alternative products of glucose metabolism affecting BBB structural and functional integrity in developing and mature brain.     

骨窗开颅与骨瓣开颅术治疗高血压脑出血的疗效对比分析

目的：研究骨窗开颅与骨瓣开颅术治疗高血压脑出血的临床疗效。方法：选取2010 年1 月到2014 年1 月我院收治的高血 压脑出血患者50 例,按照随机数字表法将患者分为A组和B组,每组25 例,A组给予骨窗开颅手术治疗,B 组给予骨瓣开颅手 术治疗,比较两组治疗的总有效率、死亡率以及并发症发生率。结果：A 组总有效率为92.0％,显著高于对照组的64.0％,比较差 异具有统计学意义（P＜0.05）;两组病死率比较差异无统计学意义（P＞0.05）;A 组并发症的发生率显著低于B 组,比较差异具有 统计学意义（P＜0.05）。结论：骨窗开颅手术治疗高血压脑出血具有较高的临床疗效,且其并发症显著低于骨瓣开颅术。     

IGF‐1 deficiency impairs neurovascular coupling in mice: implications for cerebromicrovascular aging

Aging is associated with marked deficiency in circulating IGF‐1, which has been shown to contribute to age‐related cognitive decline. Impairment of moment‐to‐moment adjustment of cerebral blood flow (CBF) via neurovascular coupling is thought to play a critical role in the genesis of age‐related cognitive impairment. To establish the link between IGF‐1 deficiency and cerebromicrovascular impairment, neurovascular coupling mechanisms were studied in a novel mouse model of IGF‐1 deficiency (Igf1^f/f‐TBG‐Cre‐AAV8) and accelerated vascular aging. We found that IGF‐1‐deficient mice exhibit neurovascular uncoupling and show a deficit in hippocampal‐dependent spatial memory test, mimicking the aging phenotype. IGF‐1 deficiency significantly impaired cerebromicrovascular endothelial function decreasing NO mediation of neurovascular coupling. IGF‐1 deficiency also impaired glutamate‐mediated CBF responses, likely due to dysregulation of astrocytic expression of metabotropic glutamate receptors and impairing mediation of CBF responses by eicosanoid gliotransmitters. Collectively, we demonstrate that IGF‐1 deficiency promotes cerebromicrovascular dysfunction and neurovascular uncoupling mimicking the aging phenotype, which are likely to contribute to cognitive impairment.