Immunoglobulin free light chains in saliva: a potential marker for disease activity in multiple sclerosis

A new procedure was developed and applied to study immunoglobulin free light chains (FLC) in saliva of healthy subjects and patients with multiple sclerosis (MS). The procedure was based on a Western blot analysis for detection and semiquantitative evaluation of monomeric and dimeric FLCs. The FLC indices accounting for the total FLC levels and for the monomer/dimer ratios of κ and λ FLC were calculated, and the cut‐off values of the FLC indices were determined to distinguish healthy state from MS disease. The obtained FLC index values were statistically different in the saliva of three groups: active MS patients, MS patients in remission and healthy subjects groups. Our FLC monomer–dimer analysis allowed differentiation between healthy state and active MS with specificity of 100% and a sensitivity of 88·5%. The developed technique may serve as a new non‐invasive complementary tool to evaluate the disease state by differentiating active MS from remission with sensitivity of 89% and specificity of 80%.     

绿原酸酰胺二聚体的合成及体外抗脂质代谢紊乱活性研究

目的设计合成绿原酸的酰胺二聚体衍生物,并对其进行体外抗脂质代谢紊乱活性的研究.方法以绿原酸为起始原料经3步反应制得目标化合物,利用HepG2细胞株评价该类化合物的调血脂活性.结果 设计并合成8个绿原酸酰胺二聚体衍生物CGA-2a~2d及CGA-3a~3d,均经波谱技术确证结构.药理实验结果表明,衍生物CGA-2d和CGA-3a~3d具有不同程度的调血脂活性.结论 绿原酸二聚体化合物CGA-2a~2d及CGA-3a~3d均为未见文献报道的新化合物,部分化合物具有潜在的调脂生物活性,具有深入研究价值.     

Apigenin,a Bioactive Flavonoid from Lycopodium clavatum,Stimulates Nucleotide Excision Repair Genes to Protect Skin Keratinocytes from Ultraviolet B-Induced Reactive Oxygen Species and DNA Damage

In this study, we examined the antioxidative and the DNA protective potentials of apigenin, a flavonoid polyphenol isolated from Lycopodium clavatum, in both in-vitro (HaCaT skin keratinocytes) and in-vivo (mice) models against UV-B radiation. We used DAPI staining in UV-B-irradiated HaCaT skin keratinocytes pre-treated with and without apigenin to assess DNA damage. We also used a flow-cytometric analysis in mice exposed to UV-B radiation with or without topical application of apigenin to assess, through a comet assay, chromosomal aberrations and quanta from reactive oxygen species (ROS) generation. Data from the stability curves for the Gibb's free energy determined from a melting-temperature profile study indicated that apigenin increased the stability of calf thymus DNA. Immunofluorescence studies revealed that apigenin caused a reduction in the number of cyclobutane pyrimidine dimers (CPDs) after 24 h, the time at which the nucleotide excision repair (NER) genes were activated. Thus, apigenin accelerated reversal of UV-B-induced CPDs through up-regulation of NER genes, removal of cyclobutane rings, inhibition of ROS generation, and down-regulation of NF-κB and MAPK, thereby revealing the precise mechanism of DNA repair.     

Ideal,catch, and slip bonds in cadherin adhesion

Classical cadherin cell-cell adhesion proteins play key morphogenetic roles during development and are essential for maintaining tissue integrity in multicellular organisms. Classical cadherins bind in two distinct conformations, X-dimer and strand-swap dimer; during cellular rearrangements, these adhesive states are exposed to mechanical stress. However, the molecular mechanisms by which cadherins resist tensile force and the pathway by which they convert between different conformations are unclear. Here, we use single molecule force measurements with an atomic force microscope (AFM) to show that E-cadherin, a prototypical classical cadherin, forms three types of adhesive bonds: catch bonds, which become longer lived in the presence of tensile force; slip bonds, which become shorter lived when pulled; and ideal bonds that are insensitive to mechanical stress. We show that X-dimers form catch bonds, whereas strand-swap dimers form slip bonds. Our data suggests that ideal bonds are formed as X-dimers convert to strand-swap binding. Catch, slip, and ideal bonds allow cadherins to withstand tensile force and tune the mechanical properties of adhesive junctions.     

A unique insertion of low complexity amino acid sequence underlies protein-protein interaction in human malaria parasite orotate phosphoribosyltransferase and orotidine 5'-monophosphate decarboxylase

Objective:To investigate the multienzyine complex formation of human malaria parasite Plasmodium falciparum[P.falciparum)orotate phosphoribosyltransferase(OPRT)and orotidine5'-monophosphate decarboxylase(OMPDC),the fifth and sixth enzyme of the de novo pyrimidine biosynthetic palhway.Previously,we have clearly established that the two enzymes in the malaria parasite exist physically as a heterotetrameric(OPRT)_2(OMPDG)_2 complex containing two subunits each of OPRT and OMPDC.and that the complex have catalytic kinetic advantages over the monofunetional enzyme.Methods:Both enzymes were cloned and expressed as recombinant proteins.The protein-protein interaction in the enzyme complex was identified using bifunctionul chemical cross-linker,liquid chromatography-mass spectrometric analysis and homology modeling,Results:The unique insertions of low complexity region at the a 2 and a 5 helices of the parasite OMPDC,characterized by single amino acid repeat sequence which was not found in homologous proteins from other organisms,was located on the OPRT-OMPDC interface.The structural models for the protein-prolein interaction of the helerotetrameric(OPRT)_2(OMPDC)_2multienzyme complex were proposed.Conclusions:Based on the proteomic data and structural modeling,it is surmised that the human malaria parasite low complexity region is responsible for the OPRT-OMPDC interaction.The structural complex of the parasite enzymes,thus,represents an efficient functional kinetic advantage,which in line with co-localization principles of evolutional origin,and allosteric control in protein-protein-interactions.     

A new simple approach for the determination of pyrimidine 5'-nucleotidase activity in human erythrocytes using an ELISA reader

Introduction: Pyrimidine 5′ nucleotidase type I (P5′N‐1) deficiency is the most frequent abnormality of cell nucleotide metabolism causing hereditary non spherocytic hemolytic anemia (HNSHA). The aim of this study was to develop a simple method of determination of P5′N‐1 activity in human erythrocytes using an ELISA reader Methods: Determination of P5′N‐1 activity is based on the liberation of inorganic phosphorus (Pi) after incubation with uridine monophosphate/cytidine monophosphate. Inorganic phosphorus (Pi), a product of the enzymatic reaction is directly quantitated from its ultraviolet absorbance. Purine/Pyrimidine nucleotides ratio (OD 260: OD 280) was also measured Results: P5′N‐1 deficient patients showed reduction in P5′N‐1 activity (Mean ± SD; 4.06 ± 0.66 using an ELISA reader & 6.25 ± 1.37 using a spectrophotometer) as compared to the normal control group (ELISA reader: 13.24 ± 3.42 & Spectrophotometer: 18.25 ± 3.20). Heterozygotes showed intermediate activity (ELISA reader: 6.06 ± 0.48 & Spectrophotometer: 8.06 ± 1.28), however they would have been missed on screening using the Purine/Pyrimidine nucleotides ratio Conclusion: Determination of P5′N‐1 activity by using an ELISA reader is a new, simple, less time consuming and reliable method. It also avoids the use of radioactive material or HPLC which is a significant advantage.     

Three new kavalactone dimers from Piper methysticum (kava)

Abstract

Three new dimeric kavalactones, designated as diyangonins A–C (1–3), along with two known analogs were isolated from the roots of Piper methysticum. Their structures were elucidated by means of extensive analysis of their 1D, 2D NMR, and mass spectroscopic data. All these dimers possess a skeleton featuring a cyclobutane ring connecting two kavalactone units in head-to-tail or head-to-head mode. Compounds 1–5 were evaluated for their cytotoxic activities against human tumor cell lines.     

多穗金粟兰乌药烷型倍半萜二聚体类化学成分研究

目的对金粟兰属植物多穗金粟兰Chloranthus multistachys根部乙醇提取物的化学成分进行研究。方法利用多种色谱技术进行分离纯化,通过理化性质和波谱数据鉴定化合物结构。结果从多穗金粟兰的氯仿和醋酸乙酯提取物中分离得到12个乌药烷型倍半萜二聚体,鉴定其结构为环银线草醇A-9-O-β-葡萄糖苷(1)、环银线草醇A(2)、银线草醇B(3)、银线草醇C(4)、银线草醇D(5)、银线草醇F(6)、银线草醇G(7)、多穗金粟兰醇B(8)、草珊瑚内酯B(9)、sarglabolide I(10)、8-O-methyltianmushanol(11)、henriol B(12)。结论化合物1、7、9~12为首次从该植物中分离得到,化合物9和10为首次从金粟兰属植物中分离得到。