How to induce defense responses in wild plant populations? Using bilberry (Vaccinium myrtillus) as example

Inducible plant defense is a beneficial strategy for plants, which imply that plants should allocate resources from growth and reproduction to defense when herbivores attack. Plant ecologist has often studied defense responses in wild populations by biomass clipping experiments, whereas laboratory and greenhouse experiments in addition apply chemical elicitors to induce defense responses. To investigate whether field ecologists could benefit from methods used in laboratory and greenhouse studies, we established a randomized block‐design in a pine‐bilberry forest in Western Norway. We tested whether we could activate defense responses in bilberry (Vaccinium myrtillus) by nine different treatments using clipping (leaf tissue or branch removal) with or without chemical treatment by methyljasmonate (MeJA). We subsequently measured consequences of induced defenses through vegetative growth and insect herbivory during one growing season. Our results showed that only MeJA‐treated plants showed consistent defense responses through suppressed vegetative growth and reduced herbivory by leaf‐chewing insects, suggesting an allocation of resources from growth to defense. Leaf tissue removal reduced insect herbivory equal to the effect of the MeJa treatments, but had no negative impact on growth. Branch removal did not reduce insect herbivory or vegetative growth. MeJa treatment and clipping combined did not give an additional defense response. In this study, we investigated how to induce defense responses in wild plant populations under natural field conditions. Our results show that using the chemical elicitor MeJA, with or without biomass clipping, may be a better method to induce defense response in field experiments than clipping of leaves or branches that often has been used in ecological field studies.     

不同手术时机治疗颅内前循环动脉瘤破裂疗效及预后分析

目的:比较不同手术时机治疗颅内前循环动脉瘤破裂患者的疗效及对患者远期预后的影响。方法:回顾性分析我院2010年3月~2015年10月收治的120例颅内前循环动脉瘤破裂患者的临床资料,所有患者均接受显微手术夹闭治疗,按手术时机分为超早期组(24 h,n=43)、早期组(24-72 h,n=36)、延期组(≥10 d,n=41),比较各组术后颅内动脉栓塞改善程度,统计各组术中及术后并发症发生情况,采用格拉斯哥量表(GOC)评定患者术后恢复情况,采用改良Rankin(m RS)表评定患者远期预后。结果:超早期组完全栓塞率略高于早期组、延期组,但对比差异无统计学意义(P0.05);超早期组术中、术后各并发症发生率略低于早期组、延期组,但对比差异无统计学意义(P0.05);术后6、12、24个月,超早期组、延期组GOS评分高于早期组、m RS评分低于早期组,超早期组GOS评分高于延期组,m RS评分低于延期组(P0.05)。结论:不同手术时机治疗颅内前循环动脉瘤破裂手术效果无明显差异,但超早期、延期手术患者术后恢复及预后评分稍优于早期手术。     

栓塞和夹闭治疗对颅内动脉瘤患者认知功能的影响

目的:评估血管内栓塞治疗和显微手术夹闭两种治疗方法对颅内动脉瘤患者认知功能的影响。方法:选取2014年3月至2015年9月重庆市中医院神经外科收治的颅内动脉瘤患者80例,按随机数字表法分为对照组和实验组各40例,对照组采用显微手术夹闭治疗,实验组采用血管内栓塞治疗。应用简易精神状态检查量表(MMSE)评估术后认知功能,并对比两组住院时间、院内死亡率和1年死亡率以及术后不良反应发生率。结果:实验组MMSE总分为(26.78±0.85)分,高于对照组的(22.25±0.63)分(P0.05);实验组认知功能障碍率为37.50%,低于对照组的55.00%(P0.05);实验组住院时间为(6.7±3.9)天,低于对照组的(9.6±4.5)天(P0.05),两组院内死亡率和1年死亡率比较无统计学差异(P0.05);两组术后不良反应发生率比较无统计学差异(P0.05)。结论:血管内介入治疗可改善颅内动脉瘤患者治疗后的认知功能,缩短住院时间。     

抗甲状腺过氧化物酶抗体水平与缺血性卒中患者颅内大动脉狭窄发生和短期转归的关系

目的:探讨急性缺血性卒中患者血清抗甲状腺过氧化物酶抗体水平与患者颅内大动脉血管有无狭窄和短期转归的关系。方法:回顾性分析225例急性缺血性卒中患者的临床资料,根据颅脑MRA、颅脑CTA及DSA结果,将卒中患者分为颅内大动脉分为血管狭窄组(n=146)和非狭窄组(n=79),并将狭窄组按狭窄程度分为1-6组,每组代表一个等级。在入院24 h内检测血清抗甲状腺过氧化物酶抗体、同型半胱氨酸、C-反应蛋白、尿酸、甲功、血脂、血糖等生化指标,入院当天采用美国国立卫生研究院卒中量表(NIHSS)评定神经功能缺损情况。在出院时或发病后14 d,采用改良Rankin量表(mRS)评估临床转归。结果:颅内大动脉血管狭窄组血清抗甲状腺过氧化物酶抗体水平显著高于非狭窄组(P0.01)。血清抗甲状腺过氧化物酶抗体(TPO-Ab)[优势比(odds ratio,OR)1.003,95%可信区间(confidence interval,CI)(1.001~1.005);P0.05]水平升高是脑梗死患者血管狭窄的独立危险因素。入院时血清抗甲状腺过氧化物酶抗体水平升高与短期转归不良有关(P0.01),但校正其他混杂因素后丧失统计学意义(OR:0.998,95%CI:0.993~1.002;P0.05。结论:急性缺血性卒中患者血清抗甲状腺过氧化物酶抗体水平是脑梗死患者血管狭窄的独立危险因素,但与血管狭窄组狭窄程度及短期转归无关短期转归无关。     

Drought mildly reduces plant dominance in a temperate prairie ecosystem across years

1. Shifts in dominance and species reordering can occur in response to global change. However, it is not clear how altered precipitation and disturbance regimes interact to affect species composition and dominance.
2. We explored community‐level diversity and compositional similarity responses, both across and within years, to a manipulated precipitation gradient and annual clipping in a mixed‐grass prairie in Oklahoma, USA. We imposed seven precipitation treatments (five water exclusion levels [?20%, ?40%, ?60%, ?80%, and ?100%], water addition [+50%], and control [0% change in precipitation]) year‐round from 2016 to 2018 using fixed interception shelters. These treatments were crossed with annual clipping to mimic hay harvest.
3. We found that community‐level responses were influenced by precipitation across time. For instance, plant evenness was enhanced by extreme drought treatments, while plant richness was marginally promoted under increased precipitation.
4. Clipping promoted species gain resulting in greater richness within each experimental year. Across years, clipping effects further reduced the precipitation effects on community‐level responses (richness and evenness) at both extreme drought and added precipitation treatments.
5. Synthesis: Our results highlight the importance of studying interactive drivers of change both within versus across time. For instance, clipping attenuated community‐level responses to a gradient in precipitation, suggesting that management could buffer community‐level responses to drought. However, precipitation effects were mild and likely to accentuate over time to produce further community change.

     

Extracellular-Purine Metabolism in Blood Vessels (Part I). Extracellular-Purine Level in Blood of Patients with Abdominal Aortic Aneurysm

Adenosine and adenosine derivatives are the main regulators of purinoceptors (P1 and P2) mediated hemostasis and blood pressure. Since impaired hemostasis and high blood pressure lead to atherosclerosis and to the development of aneurysm, in this study we tested and compared the concentration of extracellular purines (e-purines) in the blood in of patients having abdominal aortic aneurysm with that from healthy volunteers. Whereas adenine nucleosides and nucleotides level in human blood plasma was analysed using reverse phase high performance liquid chromatography (HPLC), cholesterol concentration was estimated by an enzymatic assay. We did not find any correlation between e-purines concentration and the age of healthy volunteers. Furthermore, the sum level of e-purines (ATP, ADP, AMP, adenosine, and inosine) in the control group did not exceed 70 μM, while it was nearly two-fold higher in the blood of patients having abdominal aortic aneurysm, (123 μM). In a special case of people with Leriche Syndrome, a disease characterized by deep atherosclerotic changes, the e-purines level had further increased. Additionally, we also report typical atherosclerotic changes in the aorta using histological assays as well as total cholesterol rise. The significant rise in cholesterol concentration in the blood of the patients with abdominal aortas aneurysm, compared with the control groups, was not unique since 23% of the healthy people also exceeded the normal level of cholesterol. Therefore, our results strongly indicate that the estimation of e-purines concentration in the blood may serve as another indicator of atherosclerosis and warrant further consideration as a futuristic diagnostic tool.     

CCL7 contributes to angiotensin II-induced abdominal aortic aneurysm by promoting macrophage infiltration and pro-inflammatory phenotype

Chemokine C-C motif ligand 7 (CCL7), a member of CC chemokine subfamily, plays pivotal roles in numerous inflammatory diseases. Hyper-activation of inflammation is an important characteristic of abdominal aortic aneurysm (AAA). Therefore, in the present study, we aimed to determine the effect of CCL7 on AAA formation. CCL7 abundance in aortic tissue and macrophage infiltration were both increased in angiotensin II (Ang II)-induced AAA mice. Ex vivo, CCL7 promoted macrophage polarization towards M1 phenotype. This effect was reversed by the blockage of CCR1, a receptor of CCL7. CCL7 up-regulated JAK2/STAT1 protein level in macrophage, and CCL7-induced M1 activation was suppressed by JAK2/STAT1 pathway inhibition. To verify the effect of CCL7 on AAA in vivo, either CCL7-neutralizing antibody (CCL7-nAb) or vehicles were intraperitoneally injected 24 hours prior to Ang II infusion and subsequently every three days for 4 weeks. CCL7-nAb administration significantly attenuated Ang II-induced luminal and external dilation as well as pathological remodelling. Immunostaining showed that CCL7-nAb administration significantly decreased aneurysmal macrophage infiltration. In conclusion, CCL7 contributed to Ang II-induced AAA by promoting M1 phenotype of macrophage through CCR1/JAK2/STAT1 signalling pathway.     

Fiber micro-architecture in the longitudinal-radial and circumferential-radial planes of ascending thoracic aortic aneurysm media

It was recently demonstrated by our group that the delamination strength of ascending thoracic aortic aneurysms (ATAA) was lower than that of control (CTRL, non-aneurysmal) ascending thoracic aorta (ATA), and the reduced strength was more pronounced among bicuspid (BAV) vs. tricuspid aortic valve (TAV) patients, suggesting a different risk of aortic dissection for BAV patients. We hypothesized that aortic valve morphologic phenotype predicts fiber micro-architectural anomalies in ATA. To test the hypothesis, we characterized the micro-architecture in the longitudinal-radial (Z-RAD) and circumferential-radial (Θ-RAD) planes of human ATA tissue that was artificially dissected medially. The outer and inner-media of CTRL-ATA, BAV-ATAA and TAV-ATAA were imaged using multi-photon microscopy in the Z-RAD and Θ-RAD planes to observe collagen and elastin. Micrographs were processed using an image-based tool to quantify several micro-architectural characteristics. In the outer-media of BAV-ATAA, elastin was more undulated and less aligned about the Θ-axis when compared with CTRL-ATA, which is consistent with increased tensile stretch at inflection point of Θ-strips of adventitial-medial half of BAV-ATAA (1.28) when compared with CTRL-ATA (1.13). With increasing age, collagen became more undulated about the Z-axis within the outer-media of TAV-ATAA, and elastin became more oriented in the Z-axis and collagen less radially-oriented within the inner-media of TAV-ATAA. This discrepancy in the micro-architecture with fibers in the inner layers being more stretched and with disrupted radially-oriented components than fibers in the outer layers may be associated with the development, progression and vascular remodeling in aneurysms arising in TAV patients.     

Pulsatile non-Newtonian haemodynamics in a 3D bifurcating abdominal aortic aneurysm model

Numerical prediction of non-Newtonian blood flow in a 3D abdominal aortic aneurysm bifurcating model is carried out. The non-Newtonian Carreau model is used to characterise the shear thinning behaviour of the human blood. A physical inlet velocity waveform incorporating a radial velocity distribution reasonably representative of a practical case configuration is employed. Case studies subject to both equal and unequal outlet pressures at iliac bifurcations are presented to display convincingly the downstream pressure influences on the flow behaviour within the aneurysm. Simulations indicate that the non-Newtonian aspects of the blood cannot at all be neglected or given a cursory treatment. The wall shear stress (WSS) is found to change significantly at both the proximal and distal ends of the aneurysm. At the peak systole, the WSS is peak around the bifurcation point, whereas the WSS becomes zero in the bifurcation point. Differential downstream pressure fields display significant effects regarding the flow evolution in the iliac arteries, whereas little or no effects are observed directly on the flow details in the aneurysm.