Biochemical Changes in Secondary Metabolites in Wounded and Deteriorated Cassava Roots

Bluish fluorescent and phenolic components were produced in cassava roots in response to cut- injury, and in relation to physiological deterioration and microbial deterioration. The former roved to consist of five coumarin components, the main three of which were scopoletin, scopolin and esculin, and the other two were scopoletin- and esculetin-containing conjugates. A main component of the latter was (+)-catechin. Some enzymes pertaining to the production of the secondary metabolites such as acid invertase, phenylalanine ammonia lyase and peroxidase were formed in cut-injured tissue and in non-infected tissue adjacent to the soft-rotten part.     

Cellular Thiol Production and Oxidation of Low-Density Lipoprotein

Compelling evidence suggests that low-density lipoprotein (LDL) is oxidized by cells within the arterial intima and that, once oxidized, it is profoundly atherogenic. The precise mechanism(s) by which cells promote the oxidation of LDL in vivo are not known; in vitro, however, oxidation of LDL can be enhanced by a number of differing mechanisms, including reaction with free and protein-bound metal ions, thiols, reactive oxygen species, lipoxygenase, myeloperoxidase and peroxynitrite. This review is concerned with the mechanisms by which cells enhance the oxidation of LDL in the presence of transition metals; in particular, the regulation, pro- and anti-oxidant consequences, and mechanism of action of cellular thiol production are examined, and contrasted with thiol-independent oxidation of LDL in the presence of transition metals.     

Dissociation of apoptosis induction and CD36 upregulation by enzymatically modified low-density lipoprotein in monocytic cells.

Modified low-density lipoprotein (LDL) has been implicated as an initiating or amplifying factor in atherogenesis. Some of its biological activities, such as apoptosis induction and upregulation of the scavenger receptor CD36, appear to share common signaling pathways in cells of the cardiovascular system. Exposure of low-differentiated monocytic cells to LDL modified with 15-lipoxygenase and secretory phospholipase A(2) induced apoptosis and upregulated CD36. Cell treatment with constituents of modified LDL, such as 13-hydroxyoctadecadienoic acid (13-HODE), 25-hydroxycholesterol, and lysophosphatidyl choline, and with an unrelated apoptogen (TNF-related apoptosis-inducing ligand) induced apoptosis. In contrast, only 13-HODE caused upregulation of CD36 expression. Cotreatment with the pan-caspase inhibitor z.VAD-fmk resulted in suppression of apoptosis, but was without any effect on CD36 expression. These data indicate that in monocytic cells enzymatically modified LDL is capable of inducing both apoptosis and upregulation of CD36 expression. However, in our cellular model, the two induction processes appear to be causally unrelated.     

Adipophilin在动脉粥样硬化病变和脂质负荷细胞中的作用研究(英文)

Adipophilin是细胞内脂质聚集和与脂质聚集有关疾病的标志物 ,巨噬细胞源性泡沫细胞的形成是动脉粥样硬化性疾病发生的重要环节 .为了探讨adipophilin在动脉粥样硬化性疾病的作用 ,通过高胆固醇饲料喂养新西兰白兔 12周 ,复制动脉粥样硬化疾病模型 ,同时测定血脂的变化和动脉壁胆固醇 ,使用HE染色、苏丹Ⅳ染色观察动脉粥样硬化病变的形成 ,使用免疫组织化学的方法观察动脉粥样硬化病变处和动物肝脏中adipophilin的表达 .结果发现 ,高胆固醇饲料喂养组血清总胆固醇、低密度脂蛋白胆固醇和动脉壁胆固醇明显增高 ,动脉粥样硬化病变面积增加到 (40 0 6± 7 2 9) % ,动脉粥样硬化病变处adipophilin表达呈阳性 ;而adipophilin在肝脏中的表达无论是高胆固醇饲料喂养组或对照组均为阴性 .使用80mg/L OxLDL与小鼠腹膜巨噬细胞共孵育 ,复制脂质负荷细胞 ,然后把构建的 1mmol/Ladipophilin反义寡核苷酸与该细胞共孵育 .结果发现 ,使用油红O染色观察的细胞内脂滴明显减少 ,生化测定细胞内胆固醇酯显著降低 ,与对照组相比 ,差别有显著性 .说明adipophilin与动脉粥样硬化病变有密切的关系 ,控制adipophilin的表达能够减少巨噬细胞细胞内胆固醇酯的聚集     

Adipophilin在动脉粥样硬化病变和脂质负荷细胞中的作用研究(英)

Adipophilin是细胞内脂质聚集和与脂质聚集有关疾病的标志物,巨噬细胞源性泡沫细胞的形成是动脉粥样硬化性疾病发生的重要环节.为了探讨adipophilin在动脉粥样硬化性疾病的作用,通过高胆固醇饲料喂养新西兰白兔12周,复制动脉粥样硬化疾病模型,同时测定血脂的变化和动脉壁胆固醇,使用HE染色、苏丹Ⅳ染色观察动脉粥样硬化病变的形成,使用免疫组织化学的方法观察动脉粥样硬化病变处和动物肝脏中adipophilin的表达.结果发现,高胆固醇饲料喂养组血清总胆固醇、低密度脂蛋白胆固醇和动脉壁胆固醇明显增高,动脉粥样硬化病变面积增加到(40.06±7.29)%,动脉粥样硬化病变处adipophilin表达呈阳性;而adipophilin在肝脏中的表达无论是高胆固醇饲料喂养组或对照组均为阴性.使用80 mg/L OxLDL与小鼠腹膜巨噬细胞共孵育,复制脂质负荷细胞,然后把构建的1 mmol/L adipophilin反义寡核苷酸与该细胞共孵育.结果发现,使用油红O染色观察的细胞内脂滴明显减少,生化测定细胞内胆固醇酯显著降低,与对照组相比,差别有显著性.说明adipophilin与动脉粥样硬化病变有密切的关系,控制adipophilin的表达能够减少巨噬细胞细胞内胆固醇酯的聚集.     

In vitro interactions of phenformin with serum lipoproteins and consequences thereof.

Turbidity developed when phenformin was added to human serum; this turbidity increased in a sigmoidal fashion with rising concentrations of phenformin (5–50 nmole/1). Centrifugation produced clearing of the solution, with collection of particulate matter on the surface of the sera.Extraction of control, and phenformin-treated sera with petroleum ether for 15 min. revealed that cholesterol and triglyceride were responsible for the turbidity. Different sera produced different turbidities with a given concentration of phenformin. No significant simple correlation existed between turbidity and serum cholesterol and/or triglyceride levels. The turbidities, produced by the addition of a constant concentration of phenformin to a series of diluted serum samples, were linearly related to the amount of serum present.The turbidities acquired by purified very-low density (VLDL), low-density (LDL), and high-density lipoprotein (HDL) fractions with phenformin were additive, and the turbidity of phenformin-treated serum was accounted for by these lipoprotein fractions. Serum free of lipoproteins did not become turbid when exposed to phenformin. Phenformin added to serum which had previously been delipidated, failed to produce turbidity. The turbidity produced by phenformin was reversible, because it could easily be cleared by dialysis.No significant differences in quantitative immunochemical reactivities were observed when control serum was compared with the subnatant of phenformin-treated serum, as determined by single radial immunodiffusion with LDL antibodies.These in vitro observations may be related to the in vivo hypolipidemic action of phenformin on hyperlipidemic subjects.     

体育运动和脂质代谢

一般健康人总胆固醇(T-Ch)、甘油三酯(TG)、高密度和低密度脂蛋白胆固醇(HDL-ch,LDL-cH)的含量随年令而增加。中年组(45-59)HDL-Ch平均值较低,男比女低,这与中国人男性45岁以后患冠心病(CHD)多于女性相吻合。冠心病及脑中风患者的HDL-ch含量比健康人低(P<0.05)。运动员的HDL-Ch含量明显高于一般健康人(P<0.01),其均值且高于不易患动脉粥样硬化(AS)的八种哺乳动物的均值(60.40mg/d1)。运动员的T-ch、TG和HDL-Ch含量低于健康人。     

Yolk hydrolase activities associated with polypeptide and oligosaccharide processing of Blattella germanica vitellin

Various aspects of the processing of Blattella germanica vitellin (Vt) in the oocyte and egg have been investigated. Employing subunit specific antibodies, the precursor product relationships among the subunits of this Vt have been determined. After endocytosis of Vt by the oocyte, the M_r 160,000 subunit Vt is cleaved to products of M_r 95,000 and M_r 50,000. In association with an unprocessed M_r 102,000 peptide, these form the subunits of the Vt of freshly ovulated eggs. Between 4 and 5 days post ovulation (at 30°C), all three subunits of Vt are again processed proteolytically before use by the embryo. Although Vt's high mannose-type oligosaccharides are trimmed during embryogenesis, their modification occurs subsequent to the day 4–5 proteolysis, precluding the possibility that changes in oligosaccharide content or structure contribute to regulating this second proteolytic event. Although the predominant oligosaccharide of Vt is Man₉GlCNAc₂, the M_r 50,000 subunit of egg-borne Vt contains a much higher proportion of Man₆GlCNAc₂ than the other two subunits; therefore, this portion of the precursor vitellogenin must be more accessible to the processing mannosidases of the endoplasmic reticulum during its biosynthesis. A microtechnique for aspirating the yolk from individual eggs in an oothecapermits its isolation free of contamination by embryonic tissue. With this procedure, the specific activity profiles of exo-α-mannosidase, exp-β-N-acetylglucosaminidase, α-glucosidase and acid phosphatase were monitored during the first 6 days after ovulation, and some of their properties were also determined. Expression of the acid phosphatase and exo-β-N-acetyl-glucosaminidase activities coincide with the day 4–5 proteolysis, while α-mannosidase remains relatively constant throughout the first 6 days. Functions for these enzymes and the oligosaccharides of Vt during Vt storage and utilization are proposed.     

PKM2-dependent glycolysis promotes the proliferation and migration of vascular smooth muscle cells during atherosclerosis

Increased glycolysis is involved in the proliferation and migration of vascular smooth muscle cells (VSMCs).Pyruvate kinase isoform M2 (PKM2),a key rate-limitin...     

Wnt5a/PKCδ信号通路介导氧化低密度脂蛋白诱导的巨噬细胞自噬

研究发现动脉粥样硬化(atherosclerosis,AS)斑块中巨噬细胞摄取氧化低密度脂蛋白(oxidized low-density lipoprotein, ox-LDL)和巨噬细胞极化等关键变化与失调性自噬关系密切. Wnt5a (wingless-type MMTV integration site family member 5a)在AS病变的富含巨噬细胞区域中高表达,然而Wnt5a是否参与巨噬细胞自噬尚未明确.本研究发现,60 mg/L ox-LDL处理Raw264.7细胞6 h时,自噬标志物LC3Ⅱ/Ⅰ显著增加,p62显著减少,且Wnt5a、PKCδ及STAT3的表达均增加.小分子干扰RNA (small interference RNA,si RNA)敲低Wnt5a后,逆转ox-LDL诱导的LC3Ⅱ/Ⅰ和PKCδ表达,上调p62表达,减少细胞内脂质蓄积. PKCδ抑制剂Rottlerin干预后,LC3Ⅱ/Ⅰ和STAT3减少,p62增加,降低细胞内脂质含量.综上,ox-LDL可能通过Wnt5a/PKCδ信号通路诱导巨噬细胞自噬.因此,深入研究Wnt5a/PKCδ通路在巨噬细胞及AS发生发展中的作用,是研究自噬机制新的着力点,并为药物干预提供新的靶点.     

Problem of proteolytic enzyme evolution

Own and literature data on putative evolution of proteolytic enzymes have been reviewed. Modern principles of peptidase classification based on evaluation of homology of more than 66 thousand gene sequences and similarity of general structural organization of almost 2.5 thousands of known enzymes are considered. The review highlights not only evolutionary interrelationships inside related peptidase families, their possible evolutionary background, but also evolutionary determined differences in certain proteolytic pathway in organisms belonging to different taxons.     

Immunogenetic study on the polymorphism of serum α2-lipoprotein in mink. III. Ld1 allotype of low-density lipoprotein

Mink Ld1 antigen of serum low-density lipoprotein was demonstrated by alloantibodies. No genetic relation was found between Ld1 and the Lpm system of very-high-density lipoprotein. The existence of an autosomal dominant gene, coding for the new alloantigenic marker, is postulated on the basis of mink breeding data.     

Heterogeneous production of metallo-type peptidases in parasites belonging to the family Trypanosomatidae

Proteolytic enzymes play a central role in the physiology of all living organisms, participating in several metabolic pathways and in different phases of parasite-host interactions. We have identified cell-associated peptidase activities in 33 distinct flagellates, including representatives of almost all known trypanosomatid genera parasitizing insects (Herpetomonas, Crithidia, Leishmania, Trypanosoma, Leptomonas, Phytomonas, Blastocrithidia and Endotrypanum) as well as the biflagellate kinetoplastid Bodo, by using SDS-PAGE containing gelatin as co-polymerized substrate and proteolytic inhibitors. Under the alkaline pH (9.0) conditions employed, all the flagellates presented at least one peptidase, with the exception of Crithidia acanthocephali and Phytomonas serpens, which did not display any detectable proteolytic enzyme activity. All the proteolytic activities were completely inhibited by 1,10-phenanthroline, a zinc-chelating agent, putatively identifying these activities as metallo-type peptidases. EDTA and EGTA, two other metallopeptidase inhibitors, E-64 (a cysteine peptidase inhibitor), pepstatin A (an aspartyl peptidase inhibitor) and PMSF (a serine peptidase inhibitor) did not interfere with the metallopeptidase activities detected in the studied trypanosomatids. Conversely, Bodo-derived peptidases were resistant to 1,10-phenanthroline and only partially inhibited by EDTA, showing a distinct inhibition profile. Together, our data demonstrated great heterogeneity of expression of metallopeptidases in a wide range of parasites belonging to the family Trypanosomatidae.