Effect of warm acupuncture on nitric oxide synthase and calcitonin gene-related peptide in a rat model of lumbar nerve root compression

BACKGROUND： Varying degrees of inflammatory responses occur during lumbar nerve root compression. Studies have shown that nitric oxide synthase （NOS） and calcitonin gene-related peptide （CGRP） are involved in secondary disc inflammation. OBJECTIVE： To observe the effects of warm acupuncture on the ultrastructure of inflammatory mediators in a rat model of lumbar nerve root compression, including NOS and CGRP contents. DESIGN, TIME AND SETTING： Randomized, controlled study, with molecular biological analysis, was performed at the Experimental Center, Sixth People＇s Hospital Affiliated to Shanghai Jiao Tong University, between September 2006 and April 2007. MATERIALS： Acupuncture needles and refined Moxa grains were purchased from Shanghai Taicheng Technology Development Co., Ltd., China; Mobic tablets were purchased from Shanghai Boehringer Ingelheim Pharmaceuticals Co., Ltd., China; enzyme linked immunosorbent assay （ELISA） kits for NOS and CGRP were purchased from ADL Biotechnology, Inc., USA. METHODS： A total of 50, healthy, adult Sprague-Dawley rats, were randomly divided into five groups normal, model, warm acupuncture, acupuncture, and drug, with 10 rats in each group. Rats in the four groups, excluding the normal group, were used to establish models of lumbar nerve root compression. After 3 days, Jiaji points were set using reinforcing-reducing manipulation in the warm acupuncture group. Moxa grains were burned on each needle, with 2 grains each daily. The acupuncture group was the same as the warm acupuncture group, with the exception of non-moxibustion. Mobic suspension （3.75 mg/kg） was used in the oral drug group, once a day. Treatment of each group lasted for 14 consecutive days. Modeling and medication were not performed in the normal group. MAIN OUTCOME MEASURES： The ultrastructure of damaged nerve roots was observed with transmission electron microscopy; NOS and CGRP contents were measured using ELISA. RESULTS： The changes of the radicular ultramicrostructure were characterized by Wallerian degeneration; nerve fibers were clearly demyelinated; axons collapsed or degenerated; outer Schwann cell cytoplasm was swollen and its nucleus was compacted. Compared with the normal group, NOS and CGRP contents in the nerve root compression zone in the model group were significantly increased （P 〈 0.01）. Nerve root edema was improved in the drug, acupuncture and the warm acupuncture groups over the model group. NOS and CGRP expressions were also decreased with the warm acupuncture group having the lowest concentration （P 〈 0.01）. CONCLUSION： In comparison to the known effects of Mobic drug and acupuncture treatments, the warm acupuncture significantly decreased NOS and CGRP expression which helped improve the ultrastructure of the compressed nerve root.

Contribution of Estrogen to Sex Dimorphic Expression of Cardiac Natriuretic Peptide and Nitric Oxide Synthase Systems in ANP Gene-Disrupted Mice

Background: Sex dimorphism in the prevalence, onset, development and progression of cardiovascular disease (CVD) is well recognized, but the mechanisms whereby sex hormones are believed to confer cardioprotection are still not fully understood. Objective: This study more closely delineates the effect of 17β-Estradiol (E2) on the expression and signaling of the cardiac NP and NOS systems, well-known cardioprotective modulators of the cardiac hypertrophy (CH) response, that both contribute to downstream production of cyclic guanosine 3’,5’-monophosphate (cGMP). Materials and Methods: Ovariectomized (OVX) female ANP+/+ and ANP-/- mice, 6 - 7 weeks old, were subjected to a five-week treatment with E2 (100 μg/100 μL/day) or vehicle (VEH). Left ventricle from these treatment groups, along with that from age-matched male ANP+/+ and ANP-/- mice was used to assess expression of these systems by real-time quantitative PCR (qPCR). Left ventricle tissue and plasma cGMP were measured by enzyme immunoassay to assess alterations in resultant downstream signaling. Results: NP system expression was unchanged across genotype, sex and E2 treatment. Sex-specific differences in NOS system expression were observed;female mice showed an increased expression of NOS system genes that were significantly elevated in all but one of the E2 treatment groups. Left ventricle tissue cGMP remained unchanged across genotype, sex and E2 treatment. Plasma cGMP levels were unchanged in ANP+/+ treatment groups. In ANP-/- treatment groups, plasma cGMP in the female OVX-E2 mice was significantly higher compared to male and female OVX-VEH mice. Conclusion: These findings demonstrate that in the absence of ANP, E2 upregulates cardiac NOS system expression to produce cGMP. This study confirms the importance of the cardiac NOS system in females;this particular system may be a promising future target for sex-specific treatments and therapies for CVD in women.

Global-scale analysis reveals distinct patterns of non-ribosomal peptide and polyketide synthase encoding genes in root and soil bacterial communities

Secondary metabolites(SMs)produced by soil bacteria,for instance antimicrobials and siderophores,play a vital role in bacterial adaptation to soil and root ecosystems and can contribute to plant health.Many SMs are non-ribosomal peptides and polyketides,assembled by non-ribosomal peptides synthetase(NRPS)and polyketide synthase(PKS)and encoded by biosynthetic gene clusters(BGCs).Despite their ecological importance,little is known about the occurrence and diversity of NRPs and PKs in soil.We extracted NRPS-and PKS-encodiing BGCs from 20 publicly available soil and root-associated metagenomes and annotated them using antiSMASH-DB.We found that the overall abundance of NRPSs and PKSs is similar in both environments,however NRPSs and PKSs were significantly clustered between soil and root samples.Moreover,the majority of identified sequences were unique to either soil-or root-associated datasets and had low identity to known BGCs,suggesting their novelty.Overall,this study illuminates the huge untapped diversity of predicted SMs in soil and root microbiomes,and indicates presence of specific SMs,which may play a role in inter-and intra-bacteriial interactions in root ecosystems.

Effect of stellate block on vasomotor factor, vascular endothelial nitricoxide synthase and pulmonary arterial pressure in rabbits with hypoxic pulmonary artery hypertension

BACKGROUND： At present, inhalation of nitrogen monoxidum （NO） or other angiotenic is widely used to cure hypoxic pulmonary artery hypertension. In addition, recent researches demonstrate that postganglionic fiber of stellate ganglion can regulate contents of blood vessel endothelium-calcitonin gene-related peptide （BVE-CGRP） and nitricoxide synthase （NOS） in lung tissue. Therefore, stellate ganglion which is blocked with the local anesthetic may cause therapeutic effects on hypoxic pulmonary artery hypertension. OBJECTIVE： To observe the effects of stellate block on calcitonin gene-related peptide （CGRP） of vasodilation factors, prostacyclin, endothelin-i of vasoconstriction factors, thromboxan, blood vessel endothelium-nitricoxide synthase （BVE-NOS） and mean arterial pressure of lung tissue in rabbits with hypoxic pulmonary artery hypertension. DESIGN： Randomly controlled animal study. SETTING： Neurological Institute of Taihe Hospital Affiliated to Yunyang Medical College. MATERIALS： A total of 24 adult Japanese rabbits of both genders and weighing 2.3 - 2.6 kg were provided by Animal Experimental Center of Hubei Academy of Medical Science. SP kit was provided by Beijing Zhongshan Biotechnology Co., Ltd.; moreover, kits of endothelin-1, CGRP, prostacyclin and thromboxan were provided by Radioimmunity Institute, Scientific and Technological Developing Center, General Hospital of Chinese PLA, and color image analytical system （Leica-Q500IW） was made in Germany. METHODS：The experiment was carried out in the Neurological Institute of Taihe Hospital affiliated to Yunyang Medical College from February to December 2002. ① Rabbits were performed with aseptic manipulation to exposure left stellate ganglion and then it was put in epidural catheter for 1 week. In addition, one end of epidural catheter was fixed near by stellate ganglion and the other end was fixed through dorsal neck. All rabbits were randomly divided into 4 groups, including normal control group, stellate block group, hypoxia group and hypoxia ＋ stellate block group, with 6 in each group. Rabbits in the normal control group were perfused with saline through epidural catheter with 0.5 mL once for three times per day and 3 successive days in total; in addition, rabbits in the stellate block group were perfused with 2.5 g/L bupivacaine through epidural catheter with 0.5 mL once for three times per day and 3 successive days in total. Rabbits in the hypoxia group were used to establish hypoxic pulmonary artery hypertension models. That was to say, the experimental rabbits were put in hypoxic box （containing sodalime and calcium chloride to absorb CO2 and water） and given various flows of oxygen and nitrogen through the two lateral wells simultaneously. And then, oxygen was monitored with oxygen-concentration monitoring device to control the concentration in （10±2）% for 8 hours per day and 2 successive weeks in total. Rabbits in the hypoxia ＋ stellate block group were used to establish hypoxia models as the same as those in the hypoxia group. Two weeks later, 2.5 g,/L bupivacaine was pushed into epidural catheter with 0.5 mL once for three times per day and 3 successive days in total. Breast was directly opened to measure mean pulmonary artery pressure.② 6 mL blood was collected through pulmonary arterial duct to measure levels of plasma CGRP, prostacyclin, endothelin-I and thromboxane with radio-immunity technique; meanwhile, immunohistochemical staining was used to observe the changes of BVE-NOS content of the experimental rabbits in all groups. MAIN OUTCOME MEASURES： Changes of CGRP, prostacyclin, endothelin-1 and thromboxane and BVE-NOS. RESULTS： A total of 24 experimental rabbits were involved in the final analysis. ①As compared with those in the normal control group, hypoxic pulmonary artery hypertension of the experimental rabbits was higher in the hypoxia group and hypoxia ＋ stellate block group after hypoxia [（3.8±0.30）, （3.16±0.45）, （2.60± 0.27） kPa, P 〈 0.05, 0.01]; CGRP was lower [（68.20 ±8.78）, （108.24 ±14.35）, （130.25 ±22.70） ng/L, P 〈 0.05, 0.01]; prostacyclin was lower [（94.45± 10.68）, （98.77± 12.31）, （155.27±20.67） ng/L, P 〈 0.01]; endothelin-1 was higher [（184.7±29.66）, （115.27± 13.62）, （98.20±11.52）, ng/L, P 〈 0.05, 0.01]; thromboxan was higher [（226.27 ±30.46）, （207.67 ±27.32）, （124.25 ± 16.89） ng/L, P 〈 0.01 ]. As compared with that in hypoxia group, hypoxic pulmonary artery hypertension was decreased in hypoxia ＋ stellate block group （P 〈 0.05）, CGRP was increased （P 〈 0.01）, and endothelin-1 was decreased remarkably （P 〈 0.05）. ② Level of BVE-NOS of the experimental rabbits was higher in stellate block group, hypoxia group and hypoxia ＋ stellate block group than that in the normal control group [（0.25±0.06）, （0.27±0.07）, （0.46± 0.12）, （0.14±0.03）, P 〈 0.05], and NOS level was higher in the hypoxia ＋ stellate block group than that in hypoxia group （P 〈 0.05）. CONCLUSION： Mean arterial pressure is decreased in rabbits with hypoxic pulmonary artery hypertension after stellate block and level of endothelin-1 is also decreased; however, levels of CGRP and NOS are increased respectively.

Self-induced Secretion Expression of Trehalose Synthase in Bacillus subtilis WB800n

Bacillus subtilis is a non-pathogenic Gram-positive bacterium that has been widely used to produce industrially and pharmaceutically relevant proteins. Trehalose, a non reducing disaccharide used as protective agent and additive in foodstuffs and pharmaceutical products, can be prepared by trehalose synthase(TreS). The present work aims to construct a robust recombinant B. subtilis to achieve the secretory expression of TreS. In this study, the treS gene from Pseudomonas putida ATCC47054 was amplified by PCR and further cloned and expressed in B. subtilis WB800 N using pHT01 as expression vector. For avoiding the use of inducer, promoter P_(srfA) was used to replace the promoter P_(grac) in pHT01 and verify the activity of recombinant trehalose synthase. The TreS activity assay was employed to evaluate the performance of recombinant B. subtilis W800 N under different phosphate concentrations, carbon sources, carbon source concentrations, nitrogen sources and pH. The results showed that the P_(srfA) promoter had a good regulation effect under pH 8.0 condition, and the enzyme activity reached 6 000 U/L. Using the PhoD as the secretory signal peptide, TreS was effectively secreted, and the extracellular enzyme activity reached 2 100 U/L, accounting for 35% of the total enzyme activity. By optimizing the medium and fermentation conditions, the extracellular enzyme activity reached 6 900 U/L in 5 L of fermentor, and the proportion reached 48%. The pHT01-P_(srfA)-PhoD-treS secretory recombinant B. subtilis constructed in this study has great potential in trehalose synthase production.

Gastric nNOS reduction accompanied by natriuretic peptides signaling pathway upregulation in diabetic mice

AIM:To investigate the relationship between neuronal nitric oxide synthase(nNOS)expression and the natriuretic peptide signaling pathway in the gastric fundus of streptozotocin(STZ)-induced diabetic mice.METHODS:Diabetic mice were induced by injection of STZ solution.Immunofluorescence labeling of HuC/D,nNOS and natriuretic peptide receptor-A,B,C(NPRs)in the gastric fundus(GF)was used to observe nNOS expression and whether NPRs exist on enteric neurons.The expression levels of nNOS and NPRs in the diabetic GF were examined by western blotting.An isometric force transducer recorded the electric field stimulation(EFS)-induced relaxation and contraction in the diabetic GF.An intracellular recording method assessed EFSinduced inhibitory junction potentials(IJP)on the GF.GF smooth muscles acquired from normal mice were incubated with different concentrations of the NPRs agonist C-type natriuretic peptide(CNP)for 24 h,after which their nNOS expressions were detected by western blotting.RESULTS:Eight weeks after injection,43 diabetic mice were obtained from mouse models injected with STZ.Immunofluorescence indicated that the number of NOS neurons was significantly decreased and that nNOS expression was significantly downregulated in the diabetic GF.The results of physiological and electrophysiological assays showed that the EFS-induced relaxation that mainly caused by NO was significantly reduced,while the contraction was enhanced in the diabetic GF.EFSinduced IJP showed that L-NAME sensitive IJP in the diabetic GF was significantly reduced compared with control mice.However,both NPR-A and NPR-B were detected on enteric neurons,and their expression levels were upregulated in the diabetic GF.The nNOS expression level was downregulated dose-dependently in GF smooth muscle tissues exposed to CNP.CONCLUSION:These findings suggested that upregulation of the NPs signaling pathway may be involved in GF neuropathy caused by diabetes by decreasing nNOS expression.

Amyloid beta-peptide worsens cognitive impairment following cerebral ischemia-reperfusion injury

Amyloid 13-peptide, a major component of senile plaques in Alzheimer＇s disease, has been implicated in neuronal cell death and cognitive impairment. Recently, studies have shown that the pathogenesis of cerebral ischemia is closely linked with Alzheimer＇s disease. In this study, a rat model of global cerebral ischemia-reperfusion injury was established via occlusion of four arteries; meanwhile, fibrillar amyloid [3-peptide was injected into the rat lateral ventricle. The Morris water maze test and histological staining revealed that administration of amyloid 13-peptide could further aggravate impairments to learning and memory and neuronal cell death in the hippocampus of rats subjected to cerebral ischemia-reperfusion injury. Western blot showed that phosphorylation of tau protein and the activity of glycogen synthase kinase 313 were significantly stronger in cerebral ischemia-reperfusion injury rats subjected to amyloid [3-peptide administration than those undergo- ing cerebral ischemia-repetfusion or amyloid 13-peptide administration alone. Conversely, the activ- ity of protein phosphatase 2A was remarkably reduced in rats with cerebral ischemia-reperfusion injury following amyloid 13-peptide administration. These findings suggest that amyloid 13-peptide can potentiate tau phosphorylation induced by cerebral ischemia-reperfusion and thereby aggravate cognitive impairment.

Regulation of adenosine triphosphate-sensitive potassium channels suppresses the toxic effects of amyloid-beta peptide(25-35)

In this study, we treated PC12 cells with 0-20 μM amyloid-β peptide （25-35） for 24 hours to induce cytotoxicity, and found that 5-20 μM amyloid-β peptide （25-35） decreased PC12 cell viability, but adenosine triphosphate-sensitive potassium channel activator diazoxide suppressed the decrease in PC12 cell viability induced by amyloid-β peptide （25-35）. Diazoxide protected PC12 cells against amyloid-β peptide （25-35）-induced increases in mitochondrial membrane potential and intracellular reactive oxygen species levels. These protective effects were reversed by the selective mitochondrial adenosine triphosphate-sensitive potassium channel blocker 5-hydroxydecanoate. An inducible nitric oxide synthase inhibitor, Nw-nitro-L-arginine, also protected PC12 cells from amyloid-β peptide （25-35）-induced increases in both mitochondrial membrane potential and intracellular reactive oxygen species levels. However, the H202-degrading enzyme catalase could not reverse the amyloid-β peptide （25-35）-induced increase in intracellular reactive oxygen species. A 24-hour exposure to amyloid-13 peptide （25-35） did not result in apoptosis or necrosis, suggesting that the increases in both mitochondrial membrane potential and reactive oxygen species levels preceded cell death. The data suggest that amyloid-β peptide （25-35） cytotoxicity is associated with adenosine triphosphate-sensitive potassium channels and nitric oxide. Regulation of adenosine triphosphate-sensitive potassium channels suppresses PC12 cell cytotoxicity induced by amyloid-β peptide （25-35）.

Glucagon-like peptide-2 modulates the nitrergic neurotransmission in strips from the mouse gastric fundus

AIM To investigate whether glucagon-like peptide-2(GLP-2) influences the neurally-induced responses in gastric strips from mice, since no data are available. METHODS For functional experiments, gastric fundal strips were mounted in organ baths containing Krebs-Henseleit solution. Mechanical responses were recorded via forcedisplacement transducers, which were coupled to a polygraph for continuous recording of isometric tension. Electrical field stimulation(EFS) was applied via two platinum wire rings through which the preparationwas threaded. The effects of GLP-2(2 and 20 nmol/L) were evaluated on the neurally-induced contractile and relaxant responses elicited by EFS. Neuronal nitric oxide synthase(n NOS) enzyme was evaluated by immunohistochemistry.RESULTS In the functional experiments, electrical field stimulation(EFS, 4-16 Hz) induced tetrodotoxin(TTX)-sensitive contractile responses, which were reduced in amplitude by GLP-2(P < 0.05). In the presence of the nitric oxide(NO) synthesis inhibitor L-NNA, GLP-2 no longer influenced the neurally-evoked contractile responses(P > 0.05). The direct smooth muscle response to methacholine was not influenced by GLP-2(P > 0.05). In the presence of guanethidine and carbachol, the addition of GLP-2 to the bath medium evoked TTX-sensitive relaxant responses that were unaffected by L-NNA(P > 0.05). EFS induced a fast NO-mediated relaxation, whose amplitude was enhanced in the presence of the hormone(P < 0.05). Immunohistochemical experiments showed a significant increase(P < 0.05) in n NOS immunoreactivity in the nerve structures after GLP-2 exposure. CONCLUSION The results demonstrate that in gastric fundal strips, GLP-2 influences the amplitude of neurally-induced responses through the modulation of the nitrergic neurotransmission and increases n NOS expression.

In vitro selected peptides bind with thymidylate synthase mRNA and inhibit its translation

Thymidylate synthase (TS), an essential enzyme for catalyzing the biosynthesis of thymidylate, is a critical therapeutic target in cancer therapy. Recent studies have shown that TS functions as an RNA-binding protein by interacting with two different sequences on its own mRNA, thus, repressing translational efficiency. In this study, peptides binding TS RNA with high affinity were isolated using mRNA display from a large peptide library (>1013 different sequences). The randomized library was subjected up to twelve rounds of in vitro selection and amplification. Comparing the amino acid com-position of the selected peptides (12th round, R12) with those from the initial random library (round zero, R0), the basic and aromatic residues in the selected peptides were enriched significantly, sug-gesting that these peptide regions might be important in the peptide-TS mRNA interaction. Categoriz-ing the amino acids at each random position based on their physicochemical properties and comparing the distributions with those of the initial random pool, an obvious basic charge characteristic was found at positions 1, 12, 17 and 18, suggesting that basic side chains participate in RNA binding. Sec-ondary structure prediction showed that the selected peptides of R12 pool represented a helical pro-pensity compared with R0 pool, and the regions were rich in basic residues. The electrophoretic gel mobility shift and in vitro translation assays showed that the peptides selected using mRNA display could bind TS RNA specifically and inhibit the translation of TS mRNA. Our results suggested that the identified peptides could be used as new TS inhibitors and developed to a novel class of anticancer agents.

Protein-protein interface analysis of the non-ribosomal peptide synthetase peptidyl carrier protein and enzymatic domains

Non-ribosomal peptide synthetases(NRPSs)are attractive targets for biosynthetic pathway engineering due to their modular architecture and the therapeutic relevance of their products.With catalysis mediated by specific protein-protein interactions formed between the peptidyl carrier protein(PCP)and its partner enzymes,NRPS enzymology and control remains fertile ground for discovery.This review focuses on the recent efforts within structural biology by compiling high-resolution structural data that shed light into the various protein-protein interfaces formed between the PCP and its partner enzymes,including the phosphopantetheinyl transferase(PPTase),adenylation(A)domain,condensation(C)domain,thioesterase(TE)domain and other tailoring enzymes within the synthetase.Integrating our understanding of how the PCP recognizes partner proteins with the potential to use directed evolution and combinatorial biosynthetic methods will enhance future efforts in discovery and production of new bioactive compounds.

长枝木霉菌非核糖体肽合成酶基因启动子NP249的克隆及功能验证

Peptaibols是由真菌非核糖体肽合成酶(NRPS)合成的多肽抗菌素,能够抑制多种病原菌,促进植物生长和诱导细胞凋亡。为了深入探究木霉菌非核糖体肽类抗菌素合成的调控机制,为通过基因工程来提高Peptaibols产量提供帮助。通过设计引物,克隆长枝木霉菌非核糖体肽合成酶基因NP249的上游启动子区域,然后构建到一个具有绿色荧光蛋白基因(GFP)融合表达载体,验证基因NP249的启动子。以长枝木霉菌总DNA为模板,使用引物249-1B和249-4X,通过PCR技术扩增克隆到了NRPS的启动区域,全长1 204 bp。通过启动子NP249替代载体上GFP启动子,分别用BamHⅠ和XmaⅠ酶切pCX-62载体和启动子片段,T4连接酶连接,构建GFP融合载体pCX-62-NP249-GFP。通过限制性内切酶介导的转化技术转化(REMI)木霉菌原生质体,得到的转化子转到含潮霉素的培养基上进行筛选,得到潮霉素抗性转化子Z249,进一步通过荧光显微镜检测转化子,转化子Z249能检测到GFP荧光。克隆到的启动子能启动GFP表达,具备启动子功能。

P450-mediated dehydrotyrosine formation during WS9326 biosynthesis proceeds via dehydrogenation of a specific acylated dipeptide substrate

WS9326A is a peptide antibiotic containing a highly unusual N-methyl-E-2-3-dehydrotyrosine(NMet-Dht)residue that is incorporated during peptide assembly on a non-ribosomal peptide synthetase(NRPS).The cytochrome P450 encoded by sas16(P450Sas)has been shown to be essential for the formation of the alkene moiety in NMet-Dht,but the timing and mechanism of the P450Sas-mediatedα,β-dehydrogenation of Dht remained unclear.Here,we show that the substrate of P450Sas is the NRPS-associated peptidyl carrier protein(PCP)-bound dipeptide intermediate(Z)-2-pent-1′-enyl-cinnamoyl-Thr-N-Me-Tyr.We demonstrate that P450Sas-mediated incorporation of the double bond follows N-methylation of the Tyr by the N-methyl transferase domain found within the NRPS,and further that P450Sas appears to be specific for substrates containing the(Z)-2-pent-1’-enyl-cinnamoyl group.A crystal structure of P450Sas reveals differences between P450Sas and other P450s involved in the modification of NRPS-associated substrates,including the substitution of the canonical active site alcohol residue with a phenylalanine(F250),which in turn is critical to P450Sas activity and WS9326A biosynthesis.Together,our results suggest that P450Sas catalyses the direct dehydrogenation of the NRPS-bound dipeptide substrate,thus expanding the repertoire of P450 enzymes that can be used to produce biologically active peptides.

Natural and engineered cyclodipeptides:Biosynthesis,chemical diversity,and engineering strategies for diversification and high-yield bioproduction.

Cyclodipeptides are diverse chemical scaffolds that show a broad range of bioactivities relevant for medicine,agriculture,chemical catalysis,and material sciences.Cyclodipeptides can be synthesized enzymatically through two unrelated enzyme families,non-ribosomal peptide synthetases(NRPS)and cyclodipeptide synthases(CDPSs).The chemical diversity of cyclodipeptides is derived from the two amino acid side chains and the modification of those side-chains by cyclodipeptide tailoring enzymes.While a large spectrum of chemical diversity is already known today,additional chemical space-and as such potential new bioactivities-could be accessed by exploring yet undiscovered NRPS and CDPS gene clusters as well as via engineering.Further,to exploit cyclodipeptides for applications,the low yield of natural biosynthesis needs to be overcome.In this review we summarize current knowledge on NRPS and CDPS-based cyclodipeptide biosynthesis,engineering approaches to further diversity the natural chemical diversity as well as strategies for high-yield production of cyclodipeptides,including a discussion of how advancements in synthetic biology and metabolic engineering can accelerate the translational potential of cyclodipeptides.

科研成果融入制药工艺学实验——阿斯巴甜前体酶法合成

将最新科研成果阿斯巴甜前体酶法合成融入制药工艺学实验教学中,在前期自行构建的肽合成酶突变体基础上,以苄氧羰基天冬氨酸和苯丙氨酸甲酯为底物,通过一步酶法合成苄氧羰基阿斯巴甜。本实验可以扩宽学生视野,熟悉利用生物酶制备高附加值化合物,掌握相关设备使用,了解科学前言,培养学生对科学研究的热爱。

Csub、BNP对急性心肌梗死患者PCI术后主要不良心血管事件的预测价值

目的探讨血清ATP合酶C亚基(Csub)、脑钠肽(BNP)对急性心肌梗死(AMI)患者经皮冠状动脉介入(PCI)术后主要不良心血管事件(MACE)的预测价值。方法选取2019年5月至2020年12月在玉环市人民医院行急诊PCI的59例AMI患者为研究对象,术后1年内发生MACE 15例(MACE组),未发生MACE 44例(无MACE组)。比较有、无MACE患者临床资料,分析PCI术后发生MACE的影响因素,同时采用ROC曲线分析这些影响因素对PCI术后发生MACE的预测效能。结果MACE组年龄、血清BNP水平均明显大于无MACE组(均P<0.05);两组患者在性别、发病至就诊时间、左心室射血分数、呼气末二氧化碳、高血压、糖尿病、ST段抬高心肌梗死、血栓抽吸、Csub、肌钙蛋白T、D-二聚体、血肌酐、中性粒细胞与淋巴细胞计数比值、Gensini评分、冠状动脉植入支架总长度等方面比较,差异均无统计学意义(均P>0.05)。将上述P<0.05的2个因素(年龄、BNP)以及P值接近于0.05的2个因素(Csub、冠状动脉植入支架总长度)纳入Cox多因素回归分析,结果显示Csub(HR=1.003)、BNP(HR=1.002)是AMI患者PCI术后发生MACE的影响因素(均P<0.05)。Csub、BNP及两者联合预测AMI患者PCI术后发生MACE的AUC、灵敏度、特异度分别为0.664、0.733、0.705,0.799、0.733、0.841以及0.779、0.533、0.955。结论行急诊PCI的AMI患者早期血清Csub和(或)BNP水平越高,术后1年内发生MACE的风险越大。

人参皂苷Rb1抑制β淀粉样蛋白_(25-35)诱导的皮层神经元tau蛋白过度磷酸化

目的 探讨人参皂苷Rb1对凝聚态β AP25 35诱导的胎鼠皮层神经元tau蛋白过度磷酸化的影响及其可能的作用机制。方法 通过蛋白免疫印迹法和免疫细胞化学染色法检测神经元tau蛋白磷酸化水平、总tau蛋白水平和糖原合成酶3β(GSK 3β)的蛋白表达水平。结果 凝聚态β AP25 35(20μmol·L-1)作用于皮层神经元12h,tau蛋白磷酸化水平和总tau蛋白水平均增高,同时GSK 3β蛋白表达也增多。用人参皂苷Rb1或GSK 3β特异性抑制剂氯 化锂预处理后,凝聚态β AP25 35诱导的tau蛋白的过度磷酸化受到明显抑制,同时GSK 3β的表达也降低。结论 人 参皂苷Rb1可通过抑制GSK 3β的表达来抑制凝聚态β AP25 35诱导的皮层神经元tau蛋白的过度磷酸化。

运用mRNA体外展示技术筛选胸苷酸合成酶RNA亲和肽

以体外选择方法筛选不同功能的核酸、肽和蛋白质是近年的研究热点,mRNA体外展示是一种新兴的高效多肽选择技术,其基本原理是通过含嘌呤霉素寡核苷酸的Linker使mRNA与它编码的肽或蛋白质共价结合,形成mRNA-蛋白质融合体,这一方法已用于多种功能肽的鉴定.以mRNA体外展示技术进行了由大容量多肽库中(>1013)筛选胸苷酸合成酶(thymidylatesynthase,TS)RNA亲和肽的研究,通过精密的实验设计,建立了一套完整有效的筛选方法,并对实验条件进行了优化.已进行了8轮筛选,结果表明,以mRNA体外展示技术获得的多肽分子,可以与TSmRNA亲和.将测序结果与初始肽库进行比较,发现亲和肽中碱性氨基酸及芳香族氨基酸含量明显增加,说明其在与RNA结合中具有重要作用.mRNA展示技术作为一种大容量文库的体外筛选方法,将广泛应用于与固定化靶物质具高度亲和性及特异性的多肽和蛋白质的筛选.

丹参酮对阿尔茨海默病样大鼠海马内乙酰胆碱酯酶和一氧化氮合酶表达的影响

目的 探讨丹参酮治疗阿尔茨海默病 ( Alzheim er’s disease,AD)样大鼠的神经化学机制。方法 应用凝聚态 β-淀粉样肽 1～ 40片段 ( Aβ1～ 40 )在大鼠海马齿状回背侧进行微量注射以建立 AD样记忆障碍的动物模型 ;利用改良的乙酰胆碱酯酶 ( ACh E)组织化学方法观察大鼠海马内各亚区胆碱能纤维的变化 ;用免疫组织化学方法检测大鼠海马内神经元型一氧化氮合酶 ( n NOS)、诱导型一氧化氮合酶 ( i NOS)的表达。结果 大鼠双侧海马内注射 Aβ1～ 40 ( 2 0μg) 14d后 ,海马内各亚区 ACh E阳性纤维面积百分比显著低于对照组 ;海马内 i NOS的表达上调 ,而 n NOS的表达则明显降低。此外 ,大鼠海马各亚区内 ACh E阳性纤维面积百分比与 i NOS细胞数存在显著负相关。丹参酮 5 0 m g/ kg连续灌胃 14d后 ,分别对上述变化有不同程度的改善作用。结论 丹参酮治疗 AD样大鼠的作用机制可能与保护脑内胆碱能系统和调节

CGRP受体拮抗剂CGRP8-37对甲醛炎性痛大鼠自发痛反应及脊髓后角NOS表达和NO含量的影响

目的 :探讨CGRP受体拮抗剂CGRP8 37对甲醛炎性痛大鼠自发痛反应及脊髓后角NOS表达和NO含量的影响。方法 :大鼠足底注射甲醛制造炎性痛模型 ;计数缩足反射次数反映自发痛程度 ;NADPH d组织化学法观察脊髓后角NOS表达 ;硝酸还原酶法测定NO-3 /NO-2 含量以反映NO含量。结果 :足底注射甲醛后 ,动物出现自发痛反应行为。足底注射甲醛后 2 4h ,双侧脊髓后角NOS表达及NO含量明显增加。预先鞘内注射CGRP8 37可使甲醛诱导的自发性缩足反射次数明显减少 ,并可明显抑制甲醛炎性痛诱导的脊髓后角NOS表达及NO含量的增加。结论 :甲醛炎性痛时 。