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41.
Abstract— Growth factors stimulate cellular protein synthesis, but the intracellular signaling mechanisms that regulate initiation of mRNA translation in neurons have not been clarified. A rate-limiting step in the initiation of protein synthesis is the formation of the ternary complex among GTP, eukaryotic initiation factor 2 (elF-2), and the initiator tRNA. Here we report that genistein, a specific tyrosine kinase inhibitor, decreases tyrosine kinase activity and the content of phosphotyrosine proteins in cultured primary cortical neurons. Genistein inhibits protein synthesis by >80% in a dose-dependent manner (10–80 μg/ml) and concurrently decreases ternary complex formation by 60%. At the doses investigated, genistein depresses tyrosine kinase activity and concomitantly stimulates PKC activity. We propose that a protein tyrosine kinase participates in the initiation of protein synthesis in neurons, by affecting the activity of elF-2 directly or through a protein kinase cascade.  相似文献   
42.
本文对血清岩藻糖测定方法进行了系统研究。血清用量由200μL减至50μL,显色反应4h内稳定。吸收峰在396nm。岩藻糖浓度40μg/mL内线性良好,批间CV=2.1%。以Sephadex-G200层析,血清岩藻糖主要存在于分子量为500kD的组分中。以本法测得30例健康人血清岩藻糖浓度为588.1±172.0μmol/L。  相似文献   
43.

Aim

Understanding how species' traits and environmental contexts relate to extinction risk is a critical priority for ecology and conservation biology. This study aims to identify and explore factors related to extinction risk between herbaceous and woody angiosperms to facilitate more effective conservation and management strategies and understand the interactions between environmental threats and species' traits.

Location

China.

Taxon

Angiosperms.

Methods

We obtained a large dataset including five traits, six extrinsic variables, and 796,118 occurrence records for 14,888 Chinese angiosperms. We assessed the phylogenetic signal and used phylogenetic generalized least squares regressions to explore relationships between extinction risk, plant traits, and extrinsic variables in woody and herbaceous angiosperms. We also used phylogenetic path analysis to evaluate causal relationships among traits, climate variables, and extinction risk of different growth forms.

Results

The phylogenetic signal of extinction risk differed among woody and herbaceous species. Angiosperm extinction risk was mainly affected by growth form, altitude, mean annual temperature, normalized difference vegetation index, and precipitation change from 1901 to 2020. Woody species' extinction risk was strongly affected by height and precipitation, whereas extinction risk for herbaceous species was mainly affected by mean annual temperature rather than plant traits.

Main conclusions

Woody species were more likely to have higher extinction risks than herbaceous species under climate change and extinction threat levels varied with both plant traits and extrinsic variables. The relationships we uncovered may help identify and protect threatened plant species and the ecosystems that rely on them.  相似文献   
44.
本文用免疫组织化学方法,分别在冰冻和石蜡切片上,对24例不同胎龄的胎儿肝比较研究了肝内 AFP~+细胞数量及其与 T,B 淋巴细胞之间的关系。结果发现 AFP 仅分布于肝细胞内,其他细胞阴性。不同胎龄的肝脏,AFP 的染色强度和阳性率不同。17周前的胎肝,AFP~+细胞最多以后逐渐减少。出生前的肝脏内只有少数 AFP~+细胞。AFP~+细胞的多少与 B 细胞分化发育无多大关系,但与 T 细胞似乎关系密切,两者呈负相关,即 AFP~+细胞多时,T 细胞很少,AFP~+减少时,T 细胞增加,提示 AFP 对 T 细胞具有抑制作用。同时也证明 B 细胞在胎肝内受 T 细胞的影响不大,主要依赖于肝脏的微环境。另外对 AFP 的生物学意义也进行了讨论。  相似文献   
45.
从崖椒(Zanthoxglum schinifolutm Sieb.et Zucc.)茎的石油醚、二氯甲烷提取物中分离得到8个化合物。经物理常数测定及光谱(UV,IR,MS,NMR)分析鉴定其为(1)白鲜碱(dictamning),(2)茵芋碱(skimmianine),(3)滨蒿内酯(scoparone),(4)崖椒内酯(schinifolin),(5)莨菪亭(scopoletin),(6)7-羟基-8-甲氧基香豆素(7-hydroxy-8-methoxycoumarin),(7)N-甲基弗林辛(N-methylflindersine),(8)β-谷甾醇(β-sitosterol),其中化合物(5)、(6)和(7)为首次从该植物中分离。  相似文献   
46.

Background

The treatment of Helicobacter pylori (H. pylori) infection is a challenge for those who cannot use amoxicillin.

Objective

To evaluate the eradication rate and adverse effects of vonoprazan and tetracycline dual therapy as first-line and rescue treatment regimens used in special populations with penicillin allergy or failed in previous amoxicillin-containing therapies.

Design

Patients enrolled were those who were H. pylori-positive with selected conditions: (1) allergic to penicillin, either naïve to treatment or had failed before; or (2) failed in previous amoxicillin-containing therapies. All enrolled patients accepted 14-day vonoprazan and tetracycline dual therapy (VT dual therapy) as follows: vonoprazan (20 mg b.i.d.) and tetracycline (500 mg t.i.d. [body weight < 70 kg] or 500 mg q.i.d. [body weight ≥ 70 kg]). H. pylori status was evaluated by 13C-urease breath test 6 weeks after treatment. All adverse effects were recorded. Some patients underwent bacterial culture and antibiotic susceptibility testing.

Results

A total of 62 patients were enrolled; 18 of them received VT dual therapy as first-line treatment, 44 patients received VT dual therapy as rescue treatment. Overall, 58 of 62 patients achieved successful eradication (93.5%), while all involved (100%,18/18) succeeded in the first-line treatment group and 40 cases (90.9%, 40/44) succeeded in the rescue treatment group. Sixty-one (61/62, 98.4%) patients completed the whole course of treatment. Adverse events occurred in 6 patients (6/62, 9.7%), while one patient quit because of skin rash. All adverse effects were mild and relieved spontaneously after H. pylori treatment. Five patients achieved successful H. pylori culture, and all strains isolated were sensitive to tetracycline.

Conclusions

For the treatment of H. pylori infection in special populations with penicillin allergy or failed in previous amoxicillin-containing therapies, a 14-day vonoprazan and tetracycline dual therapy was effective and safe as first-line and rescue treatment in our study. Further study is warranted to verify its efficacy, especially for those who cannot use amoxicillin.  相似文献   
47.
从1985年开始,陆续从国外实验动物著名机构引进常用近交系小鼠共23个品系(亚系和亚群)。在多年来保种繁殖过程中,根据修饰平行线系统选择留种动物,同时对动物进行全兄妹近亲交配繁殖,保持完整的谱系记录,控制饲养环境条件,成功地保持了绝大多数品系。同时对多数品系的繁殖性能和体重增长进行了观察,为这些品系的实验应用提供基本参数。  相似文献   
48.
表观遗传调控是真核生物基因表达精细调控的重要组成部分,主要包括DNA甲基化、组蛋白修饰和染色质重塑。其中,染色质重塑因子可影响组蛋白修饰酶和转录因子与特定位点的结合,在基因表达调控中占有重要地位。INO80复合物是进化上保守的染色质重塑复合物,能利用ATP水解获得的能量促进核小体的滑动和驱逐。INO80复合物除了在DNA复制、修复中发挥重要功能外,还通过改变DNA可及性调控酿酒酵母的基因表达。本文综述了染色质重塑复合物的分类及组成,重点介绍了酿酒酵母多亚基复合物INO80在基因表达调控中的重要功能,包括驱逐RNA聚合酶Ⅱ、响应信号转导途径和改变基因表达水平等,并着重总结了其在酿酒酵母环境胁迫响应机理中的研究进展。深入研究INO80染色质重塑复合物的功能,可为理解真核生物精细代谢调控的机制,并进一步开发基于染色质重塑等表观调控水平的微生物代谢工程和合成生物学改造策略,提高菌株的环境胁迫耐受性和发酵性能提供基础。  相似文献   
49.
Few approaches have been conducted in the treatment of renal cell carcinoma (RCC) after nephrectomy, resulting in a high mortality rate in urological tumours. Mitophagy is a mechanism of mitochondrial quality control that enables selective degradation of damaged and unnecessary mitochondria. Previous studies have found that glycerol-3-phosphate dehydrogenase 1-like (GPD1L) is associated with the progression of tumours such as lung cancer, colorectal cancer and oropharyngeal cancer, but the potential mechanism in RCC is still unclear. In this study, microarrays from tumour databases were analysed. The expression of GPD1L was confirmed by RT–qPCR and western blotting. The effect and mechanism of GPD1L were explored using cell counting kit 8, wound healing, invasion, flow cytometry and mitophagy-related experiments. The role of GPD1L was further confirmed in vivo. The results showed that GPD1L expression was downregulated and positively correlated with prognosis in RCC. Functional experiments revealed that GPD1L prevented proliferation, migration and invasion while promoting apoptosis and mitochondrial injury in vitro. The mechanistic results indicated that GPD1L interacted with PINK1, promoting PINK1/Parkin-mediated mitophagy. However, inhibition of PINK1 reversed GPD1L-mediated mitochondrial injury and mitophagy. Moreover, GPD1L prevented tumour growth and promoted mitophagy by activating the PINK1/Parkin pathway in vivo. Our study shows that GPD1L has a positive correlation with the prognosis of RCC. The potential mechanism involves interacting with PINK1 and regulating the PINK1/Parkin pathway. In conclusion, these results reveal that GPD1L can act as a biomarker and target for RCC diagnosis and therapy.  相似文献   
50.
Eels are important aquaculture species for which an increasing number of reference genes are being identified and applied. In this study, five housekeeping genes [RPL7 (ribosomal protein L7), 18 S (18 S ribosomal RNA), EF1A (elongation factor 1α), ACTB (β-actin) and GAPDH (glyceraldehyde-3-phosphate dehydrogenase)] were chosen to evaluate their reliability as reference genes for quantitative real-time PCR (qPCR) for the study of Anguilla anguilla. The expression of the selected genes in different eel tissues was determined using qPCR at different growth stages or upon challenge by Anguillid herpesvirus (AngHV), and the expression levels of these genes were then compared and evaluated using the geNorm and NormFinder algorithms. Then, RefFinder was used to comprehensively rank the examined housekeeping genes. Interestingly, the expression of the evaluated housekeeping genes exhibited tissue-dependent and treatment-dependent variations. In different growth periods A. anguilla tissues, the most stable genes were the following: ACTB in mucus; 18 S in skin and kidney; RPL7 in muscle, gill, intestine and brain; EF1A in heart and liver; and GAPDH in spleen. In contrast, in AngHV-challenged A. anguilla tissues, the most stable genes were the following: 18 S in mucus; RPL7 in skin, gill, heart, spleen, kidney and intestine; EF1A in muscle and liver; and ACTB in brain. Further comparison analysis indicated that the expression of RPL7 and EF1A was stable in multiple A. anguilla tissues in different growth periods and in eels challenged by AngHV. Nonetheless, the expression level of GAPDH in eel tissues was lower, and it was unstable in several tissues. These results indicated that the selection of reference genes for qPCR analysis in A. anguilla should be made in accordance with experimental parameters, and both RPL7 and EF1A could be used as reference genes for qPCR study of A. anguilla at different growth stages or upon challenge by AngHV. The reference genes identified in this study could improve the accuracy of qPCR data and facilitate further studies aimed at understanding the biology of eels.  相似文献   
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