Cleavage of von Willebrand factor by granzyme M destroys its factor VIII binding capacity

Von Willebrand factor (VWF) is a pro-hemostatic multimeric plasma protein that promotes platelet aggregation and stabilizes coagulation factor VIII (FVIII) in plasma. The metalloproteinase ADAMTS13 regulates the platelet aggregation function of VWF via proteolysis. Severe deficiency of ADAMTS13 is associated with thrombotic thrombocytopenic purpura, but does not always correlate with its clinical course. Therefore, other proteases could also be important in regulating VWF activity. In the present study, we demonstrate that VWF is cleaved by the cytotoxic lymphocyte granule component granzyme M (GrM). GrM cleaved both denaturated and soluble plasma-derived VWF after Leu at position 276 in the D3 domain. GrM is unique in that it did not affect the multimeric size and pro-hemostatic platelet aggregation ability of VWF, but instead destroyed the binding of VWF to FVIII in vitro. In meningococcal sepsis patients, we found increased plasma GrM levels that positively correlated with an increased plasma VWF/FVIII ratio in vivo. We conclude that, next to its intracellular role in triggering apoptosis, GrM also exists extracellularly in plasma where it could play a physiological role in controlling blood coagulation by determining plasma FVIII levels via proteolytic processing of its carrier VWF.     

Heterophile infectious mononucleosis antigen used in the latex diagnostic test. I. A method of antigen isolation and its serologic activity

The aim of this study was to elaborate a method of heterophile mononucleosis antigen preparation useful for latex coating. This antigen was isolated from bovine red blood cells stroma by the technique of Schwarzweiss and Tomcsik with author's own modification, in which introductory extraction of erythrocytes stroma ++ was performed by means of trichloracetic acid, aqueous extraction and elution of active substance with 80% ethanol. Besides of heterophile antigen preparation obtained by the method of Schwerzweiss and Tomcsik (preparation S-T) two serologically++ active preparations were obtained (fraction I and IV), which ability to inhibit PBD agglutinating reaction and bovine red blood cells haemolysis was 16 and 8 times lower, respectively, than S-T preparation. The preparation of heterophile mononucleosis antigen obtained differed in latex coating efficacy. In order to prepare latex reagent MZ-I (from fraction I) a solution of preparation of 125 micrograms/ml concentration was used, for MZ-II (from fraction IV)--50 micrograms and for MZ-III (from preparation S-T)--15 micrograms/ml. The reagent MZ-I showed, the highest activity in agglutinating test with human serum containing heterophile mononucleosis antibodies while two others reacted with 2-4 times lover serum dilutions. Similar differentiated reactivity with these reagents was found in latex test with 15 sera from patients suspected of having infectious mononucleosis.     

Association of TERC and OBFC1 Haplotypes with Mean Leukocyte Telomere Length and Risk for Coronary Heart Disease

Objective

To replicate the associations of leukocyte telomere length (LTL) with variants at four loci and to investigate their associations with coronary heart disease (CHD) and type II diabetes (T2D), in order to examine possible causal effects of telomere maintenance machinery on disease aetiology.

Methods

Four SNPs at three loci BICD1 (rs2630578 GγC), 18q12.2 (rs2162440 GγT), and OBFC1 (rs10786775 CγG, rs11591710 AγC) were genotyped in four studies comprised of 2353 subjects out of which 1148 had CHD and 566 T2D. Three SNPs (rs12696304 CγG, rs10936601G>T and rs16847897 GγC) at the TERC locus were genotyped in these four studies, in addition to an offspring study of 765 healthy students. For all samples, LTL had been measured using a real-time PCR-based method.

Results

Only one SNP was associated with a significant effect on LTL, with the minor allele G of OBFC1 rs10786775 SNP being associated with longer LTL (β=0.029, P=0.04). No SNPs were significantly associated with CHD or T2D. For OBFC1 the haplotype carrying both rare alleles (rs10786775G and rs11591710C, haplotype frequency 0.089) was associated with lower CHD prevalence (OR: 0.77; 95% CI: 0.61–0.97; P= 0.03). The TERC haplotype GTC (rs12696304G, rs10936601T and rs16847897C, haplotype frequency 0.210) was associated with lower risk for both CHD (OR: 0.86; 95% CI: 0.75-0.99; P=0.04) and T2D (OR: 0.74; 95% CI: 0.61–0.91; P= 0.004), with no effect on LTL. Only the last association remained after adjusting for multiple testing.

Conclusion

Of reported associations, only that between the OBFC1 rs10786775 SNP and LTL was confirmed, although our study has a limited power to detect modest effects. A 2-SNP OBFC1 haplotype was associated with higher risk of CHD, and a 3-SNP TERC haplotype was associated with both higher risk of CHD and T2D. Further work is required to confirm these results and explore the mechanisms of these effects.     

嗜盐隐杆藻胞外多糖的分离、纯化及理化特性

嗜盐隐杆藻（Ａｐｈａｎｏｔｈｅｃｅ ｈａｔｏｐｈｙｔｉｃａ）培养液经离心,浓缩、透析、有机溶剂沉淀得胞外多糖（Ｅｘｏｐｏｌｙｓａｃｃｈａｒｉｄｅｓ,ＥＰＳ）粗品,经ＤＥＡＥ－纤维素二次柱层析纯化得ＥＰＳ精品。葡聚糖Ｇ－２００凝胶过滤表明其为单一组份。对其进行理化测试并对各组分进行定量分析,多糖、已糖醛酸、硫酸根含量分别为４０．９６％２３．２７％和３４．４６％,元素分析你测得Ｃ、Ｈ、Ｎ、Ｓ含量分别为     

Direct evidence of Toxoplasma-induced changes in serum testosterone in mice

Latent toxoplasmosis is known to influence the morphology of infected persons and also increases the probability of the birth of male offspring in both humans and mice. All these traits can be related to the observed differences in the concentration of testosterone between Toxoplasma-infected and Toxoplasma-free subjects. However, it is not possible to decide, using the Toxoplasma-human model, whether toxoplasmosis influences the level of testosterone in the infected host or whether individuals with different levels of testosterone vary in the probability of toxoplasma infection. Here we studied changes in the testosterone levels in the latent phase of toxoplasmosis in laboratory mice artificially infected with cystogenic but relatively virulent strain T38 of T. gondii. We observed decreased testosterone levels in both female and male mice with latent toxoplasmosis in comparison to uninfected controls (P = 0.001). The present results indicate that Toxoplasma infection changes the concentration of serum testosterone in mice and human rather than changed concentration of testosterone influences the probability of the Toxoplasma infection. It is possible that the decrease of testosterone is an adaptive mechanism of infected mice aimed to compensate toxoplasmosis-induced immunosuppression observed during latent Toxoplasma infection.     

Xylosandrus germanus in Central Europe: Spread into and within the Czech Republic

Invasive organisms represent great threats to ecosystems and great challenges to forest management. In Europe, the black timber bark beetle (Xylosandrus germanus) is an invasive secondary pest that mostly attacks the logs of felled trees. We showed the invasion history for Europe and using many local surveys, we summarize the current distribution and other available information on X. germanus in the Czech Republic. We report that this species is distributed from the lowlands to the mountains in the Czech Republic; it is widespread in the eastern half of the country, where it is more abundant in the warmer south and southeast areas than in the cooler areas. Most (78%) of the known localities are at elevation below 400 m a.s.l. Although an ice storm greatly increased X. germanus abundance near the border with Austria, its high abundance did not result in damage to standing trees. Presence of X. germanus in the Czech Republic for over 10 years has not led to heavy tree infestation.     

The MIG-2/integrin interaction strengthens cell-matrix adhesion and modulates cell motility

Integrin-mediated cell-matrix adhesion plays an important role in control of cell behavior. We report here that MIG-2, a widely expressed focal adhesion protein, interacts with beta1 and beta3 integrin cytoplasmic domains. Integrin binding is mediated by a single site within the MIG-2 FERM domain. Functionally, the MIG-2/integrin interaction recruits MIG-2 to focal adhesions. Furthermore, using alphaIIbbeta3 integrin-expressing Chinese hamster ovary cells, a well described model system for integrin activation, we show that MIG-2 promotes integrin activation and enhances cell-extracellular matrix adhesion. Although MIG-2 is expressed in many cell types, it is deficient in certain colon cancer cells. Expression of MIG-2, but not of an integrin binding-defective MIG-2 mutant, in MIG-2-null colon cancer cells strengthened cell-matrix adhesion, promoted focal adhesion formation, and reduced cell motility. These results suggest that the MIG-2/integrin interaction is an important element in the cellular control of integrin-mediated cell-matrix adhesion and that loss of this interaction likely contributes to high motility of colon cancer cells.     

Structure of AscE and induced burial regions in AscE and AscG upon formation of the chaperone needle-subunit complex of type III secretion system in Aeromonas hydrophila

In the type III secretion system (T3SS) of Aeromonas hydrophila, the putative needle complex subunit AscF requires both putative chaperones AscE and AscG for formation of a ternary complex to avoid premature assembly. Here we report the crystal structure of AscE at 2.7 A resolution and the mapping of buried regions of AscE, AscG, and AscF in the AscEG and AscEFG complexes using limited protease digestion. The dimeric AscE is comprised of two helix-turn-helix monomers packed in an antiparallel fashion. The N-terminal 13 residues of AscE are buried only upon binding with AscG, but this region is found to be nonessential for the interaction. AscE functions as a monomer and can be coexpressed with AscG or with both AscG and AscF to form soluble complexes. The AscE binding region of AscG in the AscEG complex is identified to be within the N-terminal 61 residues of AscG. The exposed C-terminal substrate-binding region of AscG in the AscEG complex is induced to be buried only upon binding to AscF. However, the N-terminal 52 residues of AscF remain exposed even in the ternary AscEFG complex. On the other hand, the 35-residue C-terminal region of AscF in the complex is resistant to protease digestion in the AscEFG complex. Site-directed mutagenesis showed that two C-terminal hydrophobic residues, Ile83 and Leu84, of AscF are essential for chaperone binding.     

Spectral characteristic of fluorescence induction in a model cyanobacterium, Synechococcus sp. (PCC 7942)

We present here three-dimensional time-wavelength-intensity displays of changes in variable fluorescence, during the O(JI)PSMT transient, observed in cyanobacterium at room temperature. We were able to measure contributions of individual chromophores to fluorescence spectra at various times of fluorescence induction (FI). The method was applied to a freshwater cyanobacterium, Synechococcus sp. (PCC 7942). Analysis of our experimental results provides the following new conclusions: (i) the main chlorophyll (Chl) a emission band at ∼ 685 nm that originates in Photosystem (PS) II exhibits typical fast (OPS) and slow (SMT) FI kinetics with both orange (622 nm) and blue (464 nm) excitation. (ii) Similar kinetics are exhibited for its far-red emission satellite band centered at ∼ 745 nm, where the PS II contribution predominates. (iii) A significant OPS-SMT-type kinetics of C-phycocyanin emission at ∼ 650 nm are observed with the blue light excitation, but not with orange light excitation where the signal rose only slightly to a maximum. The induction of F650 was not caused by an admixture of the F685 fluorescence and thus our data show light-inducible and dark-reversible changes of phycobilin fluorescence in vivo. We discuss possible interpretations of this new observation.