Thermosensitive heparin‐poloxamer hydrogel encapsulated bFGF and NGF to treat spinal cord injury

The application of growth factors (GFs) for treating chronic spinal cord injury (SCI) has been shown to promote axonal regeneration and functional recovery. However, direct administration of GFs is limited by their rapid degradation and dilution at the injured sites. Moreover, SCI recovery is a multifactorial process that requires multiple GFs to participate in tissue regeneration. Based on these facts, controlled delivery of multiple growth factors (GFs) to lesion areas is becoming an attractive strategy for repairing SCI. Presently, we developed a GFs‐based delivery system (called GFs‐HP) that consisted of basic fibroblast growth factor (bFGF), nerve growth factor (NGF) and heparin‐poloxamer (HP) hydrogel through self‐assembly mode. This GFs‐HP was a kind of thermosensitive hydrogel that was suitable for orthotopic administration in vivo. Meanwhile, a 3D porous structure of this hydrogel is commonly used to load large amounts of GFs. After single injection of GFs‐HP into the lesioned spinal cord, the sustained release of NGF and bFGF from HP could significantly improve neuronal survival, axon regeneration, reactive astrogliosis suppression and locomotor recovery, when compared with the treatment of free GFs or HP. Moreover, we also revealed that these neuroprotective and neuroregenerative effects of GFs‐HP were likely through activating the phosphatidylinositol 3 kinase and protein kinase B (PI3K/Akt) and mitogen‐activated protein kinase/extracellular signal‐regulated kinase (MAPK/ERK) signalling pathways. Overall, our work will provide an effective therapeutic strategy for SCI repair.     

新早期胃癌标志物PRDX4通过清除ROS促进胃癌的发生发展

胃癌是全球第四大最常见的癌症,也是全球癌症中引起死亡的第二大原因。为了降低胃癌的死亡率,目前亟需解决的问题是发现新的早期胃癌特异性的标志物,提高早期胃癌的检出率,从而从根本上解决胃癌死亡率高的问题。实验室前期研究发现过氧化物酶4 (Peroxiredoxin 4,PRDX4)具有早期胃癌标志物的潜能,文中通过建立恶性转化模型及转化细胞过表达等方法,研究PRDX4在转化细胞中的作用。结果显示PRDX4通过减少转化细胞中活性氧(Reactive oxygen species,ROS)含量,使细胞处在利于生长增殖的微环境中,从而促进细胞发生恶性转化,即PRDX4通过清除ROS促进胃癌的发生发展。     

轻度支气管哮喘儿童的诱导痰菌群特征

目的探讨轻度支气管哮喘儿童的诱导痰菌群特征及临床意义。方法纳入年龄为6~12周岁于2018年11月至2019年1月在深圳市儿童医院呼吸科门诊定期复诊的轻度支气管哮喘患儿51例(哮喘组),留取诱导痰,匹配同年龄段97例健康无过敏儿童的口咽拭子作为对照。诱导痰及口咽拭子提取总DNA并扩增,对16S rRNA基因进行高通量测序并对测序结果进行生物信息学分析。结果NMDS分析结果显示哮喘组与健康对照组研究对象菌群结构存在差异;哮喘组的诱导痰菌群多样性指数(Shannon index)高于健康对照组(2.34±0.53 vs 1.87±0.50,P<0.05)。门水平分析显示,哮喘组与健康对照组的菌群均主要为厚壁菌门(38.34%vs 44.74%,P<0.05)、变形杆菌门(31.14%vs 19.78%,P<0.05)、拟杆菌门(14.59%vs 20.52%,P<0.05)、放线菌门(10.41%vs 7.85%,P<0.05)和梭杆菌门(2.82%vs 6.67%,P<0.05),但两组之间的构成比有明显差异。与健康对照组相比,在属水平上哮喘组韦荣球菌属(5.27%vs 8.96%)、普雷沃菌属(8.38%vs 17.35%)、罗斯菌属(1.50%vs 5.46%)、纤毛菌属(1.37%vs 4.39%)等非条件致病菌属比例明显下降(均P<0.05),而嗜血杆菌属(9.83%vs 6.17%)、卟啉单胞菌属(2.48%vs 1.41%)、莫拉菌属(5.66%vs 0.42%)、诺卡菌属(3.40%vs 0.00%)等条件致病菌属比例明显上升(均P<0.05)。结论尽管轻度支气管哮喘患儿已临床控制,但诱导痰内菌群仍存在结构紊乱。气道菌群紊乱可能是儿童支气管哮喘的发病机制之一。除了致病菌属外,非致病菌菌属的构成变化可能也是儿童哮喘的一个发生机制。     

黄土区不同恢复年限草地群落生物量及根冠比对氮添加的响应

大气氮沉降增加作为全球变化的主要环境问题之一,已引发人们的广泛关注,持续的氮沉降对草地生态系统的组成、结构和功能产生重要影响。为深入了解草地恢复进程中群落生物量和根冠比对氮沉降的响应,以黄土区3个不同恢复年限（初期12a、中期28a和后期37a）的天然草地为研究对象,通过设置6个氮添加水平,CK （0）、N1（2.34g m^-2a^-1）、N2（4.67g m^-2a^-1）、N3（9.34g m^-2a^-1）、N4（18.68g m^-2a^-1）、N5（37.35g m^-2a^-1）来测定草地群落地上生物量、地下生物量和总生物量,并计算根冠比和氮响应效率（NRE）。结果表明：（1）地上生物量在恢复中期最大,随氮添加梯度增加,地上生物量在恢复初期和恢复后期呈不显著上升趋势,对氮添加表现为非线性的正响应（ΔNRE>0）,在恢复中期呈不显著下降趋势,对氮添加表现为非线性的负响应（ΔNRE<0）。（2）群落地下生物量对氮添加无显著响应,总生物量只有在恢复后期的N4添加水平下,与对照存在显著差异。（3）根冠比在恢复初期时,N3添加水平下显著高于对照和其他氮添加水平,其余恢复年限对氮添加无显著响应。综上所述,通过分析比较黄土区不同恢复年限草地群落的地上、地下及总生物量和根冠比对氮添加的响应。建议对该区域开展试点实验,实行适应性草地管理,如进行两年一次刈割或轻度放牧（2只羊/hm²）,来探寻更科学有效的管理措施,使草地实现系统性恢复,进而满足生态系统容量和社会需求的变化。     

The fate of cyanobacterial detritus in the food web of Lake Taihu: a mesocosm study using 13C and 15N labeling

The ecosystem of the highly eutrophic Lake Taihu (China) is seriously affected by recurrent cyanobacterial blooms, but little is known about the contribution made by cyanobacteria to the food web. In this study, we investigated the fate of detritus of the cyanobacterium Microcystis in the food web of Lake Taihu through a 19-day mesocosm experiment using stable-isotopic tracers of carbon (¹³C) and nitrogen (¹⁵N). ¹³C- and ¹⁵N-labeled Microcystis detritus was added to the mesocosm tanks and tracked through different elements of the food web. We found clear enrichment with both ¹³C and ¹⁵N in some zooplankton species, including Daphnia, Diaphanosoma, and Sinocalanus, which suggests that these zooplankters can utilize cyanobacterial detritus as a food source. Benthic animals, chironomid larvae and Limnodrilus, also showed pronounced increases in ¹³C and ¹⁵N, but the isotope increase was relatively smaller in the gastropods, Radix sp. and Bellamya sp., implying that they either exploited this food source differently or responded slower than the zooplankton, which apparently grew faster than the snails. Our study suggests that cyanobacterial detritus, originating almost wholly from the bloom-forming Microcystis, is an important food source for both planktonic and benthic food webs in eutrophic lakes such as Lake Taihu.     

Synthesis and antiproliferative activity of C-homo-lactam derivatives of 7-deoxycholic acid

Using deoxycholic acid as starting materials, a series of 12a-aza-C-homo-12-one 7-deoxycholic acid derivatives were synthesized The antiproliferative activity of the synthesized compounds against some carcinoma cell lines was investigated. The results showed that some 12-oxy-12a-aza-C-homo-7-deoxycholic acid derivatives displayed distinct cytotoxicity to HeLa (human cervical carcinoma) and Tu 686 (laryngocarcinoma) tumor cell lines. In particular, the IC₅₀ values of the compounds 6 and 7 against Tu 686 cells are 16.7 and 19.8 μM/L respectively. The information obtained from the studies may be useful for the design of novel chemotherapeutic drugs.