Elevated Procoagulant Endothelial and Tissue Factor Expressing Microparticles in Women with Recurrent Pregnancy Loss

Background

15% of reproducing couples suffer from pregnancy loss(PL) and recurs in 2-3%. One of the most frequently hypothesized causes of unexplained PL refers to a defective maternal haemostatic response leading to uteroplacental thrombosis. Hereditary thrombophilia and antiphospholipid antibodies have been extensively described as risk factors for PL in women with unknown aetiology. Recently, a new marker has emerged: the cell-derived procoagulant circulating microparticles(MPs) which have been reported to have a major role in many thrombosis complicated diseases. This study aims to analyze the significance of procoagulant MPs in women suffering from unexplained recurrent pregnancy loss(RPL), and characterize their cellular origin.

Method and Findings

115 women with RPL were analyzed for common thrombophilia markers and different cell derived MPs-total annexinV, platelet(CD41a), endothelial(CD146,CD62e), leukocyte(CD45), erythrocyte(CD235a) and tissue factor(CD142)(TF) expressing MPs and were compared with 20 healthy non-pregnant women. Methodology for MP analysis was standardized by participating in the “Vascular Biology Scientific and Standardization Committee workshop”.

Results

Total annexinV, TF and endothelial MPs were found significantly increased(p<0.05, 95% confidence interval) in women with RPL. The procoagulant activity of MPs measured by STA-PPL clotting time assay was found in correspondence with annexinV MP levels, wherein the clot time was shortened in samples with increased MP levels. Differences in platelet, leukocyte and erythrocyte derived MPs were not significant. Thirty seven of 115 women were found to carry any of the acquired or hereditary thrombophilia markers. No significant differences were seen in the MP profile of women with and without thrombophilia marker.

Conclusion

The presence of elevated endothelial, TF and phosphatidylserine expressing MPs at a distance (at least 3 months) from the PL suggests a continued chronic endothelial damage/activation which may get exaggerated at the onset of pregnancy. The data suggests that MPs may contribute to uteroplacental thrombosis and are associated with the pathogenesis of RPL.     

Interactions between immunity,proliferation and molecular subtype in breast cancer prognosis

Background

Gene expression signatures indicative of tumor proliferative capacity and tumor-immune cell interactions have emerged as principal biology-driven predictors of breast cancer outcomes. How these signatures relate to one another in biological and prognostic contexts remains to be clarified.

Results

To investigate the relationship between proliferation and immune gene signatures, we analyzed an integrated dataset of 1,954 clinically annotated breast tumor expression profiles randomized into training and test sets to allow two-way discovery and validation of gene-survival associations. Hierarchical clustering revealed a large cluster of distant metastasis-free survival-associated genes with known immunological functions that further partitioned into three distinct immune metagenes likely reflecting B cells and/or plasma cells; T cells and natural killer cells; and monocytes and/or dendritic cells. A proliferation metagene allowed stratification of cases into proliferation tertiles. The prognostic strength of these metagenes was largely restricted to tumors within the highest proliferation tertile, though intrinsic subtype-specific differences were observed in the intermediate and low proliferation tertiles. In highly proliferative tumors, high tertile immune metagene expression equated with markedly reduced risk of metastasis whereas tumors with low tertile expression of any one of the three immune metagenes were associated with poor outcome despite higher expression of the other two metagenes.

Conclusions

These findings suggest that a productive interplay among multiple immune cell types at the tumor site promotes long-term anti-metastatic immunity in a proliferation-dependent manner. The emergence of a subset of effective immune responders among highly proliferative tumors has novel prognostic ramifications.     

Concerted action of exonuclease and Gap-dependent endonuclease activities of FEN-1 contributes to the resolution of triplet repeat sequences (CTG)n- and (GAA)n-derived secondary structures formed during maturation of Okazaki fragments

There is much evidence to indicate that FEN-1 efficiently cleaves single-stranded DNA flaps but is unable to process double-stranded flaps or flaps adopting secondary structures. However, the absence of Fen1 in yeast results in a significant increase in trinucleotide repeat (TNR) expansion. There are then two possibilities. One is that TNRs do not always form stable secondary structures or that FEN-1 has an alternative approach to resolve the secondary structures. In the present study, we test the hypothesis that concerted action of exonuclease and gap-dependent endonuclease activities of FEN-1 play a role in the resolution of secondary structures formed by (CTG)n and (GAA)n repeats. Employing a yeast FEN-1 mutant, E176A, which is deficient in exonuclease (EXO) and gap endonuclease (GEN) activities but retains almost all of its flap endonuclease (FEN) activity, we show severe defects in the cleavage of various TNR intermediate substrates. Precise knock-in of this point mutation causes an increase in both the expansion and fragility of a (CTG)n tract in vivo. Taken together, our biochemical and genetic analyses suggest that although FEN activity is important for single-stranded flap processing, EXO and GEN activities may contribute to the resolution of structured flaps. A model is presented to explain how the concerted action of EXO and GEN activities may contribute to resolving structured flaps, thereby preventing their expansion in the genome.     

3-D QSAR studies on new dibenzyltin(IV) anticancer agents by comparative molecular field analysis (CoMFA).

Dibenzyltin(IV)dichloride and dibenzyltin(IV)diisothiocyanate derivatives with N,S-donor ligands show significant cytotoxic activities against human cancer cell lines, and are well compared to analogous dialkyltin(IV) derivatives. CoMFA models were generated for the first time for these organotin derivatives using the cytotoxic activities (against two human tumor cell lines, MCF-7, a mammary carcinoma and WiDr, a colon carcinoma) of 21 complexes. High r(2) and r(2)(cv) values for both CoMFA models indicate good predictive power for the models.     

Structure of the type III secretion and substrate-binding domain of Yersinia YopH phosphatase

Pathogenic strains of Yersinia deploy a type III secretion system to inject the potent tyrosine phosphatase YopH into host cells, where it dephosphorylates focal adhesion-associated substrates. The amino-terminal, non-catalytic domain of YopH is bifunctional; it is essential for the secretion and binding of the specific chaperone SycH, but also targets the catalytic domain to substrates in the infected cell. We describe the 2.2 A resolution crystal structure of residues 1-129 of YopH from Yersinia pseudotuberculosis. The amino-terminal alpha-helix (2-17), comprising the secretion signal, and beta-strand (24-28) of one molecule exchange with another molecule to form a domain-swapped dimer. Nuclear magnetic resonance (NMR) and gel filtration experiments demonstrated that YopH(1-129) could exist as a monomer and/or a dimer in solution. The topology of the dimer and the dynamics of a monomeric form in solution observed by NMR imply that YopH has the propensity to unfold partially. The dimer is probably not important physiologically, but may mimic how SycH binds to the exposed non-polar surfaces of a partially unfolded YopH. Phosphopeptide-induced perturbations in NMR chemical shifts define a substrate-binding surface on YopH(1-129) that includes residues previously shown by mutagenesis to be essential for YopH function.     

Design and Development of Gliclazide Mucoadhesive Microcapsules: In Vitro and In Vivo Evaluation

In this study an attempt was made to prepare mucoadhesive microcapsules of gliclazide using various mucoadhesive polymers designed for oral controlled release. Gliclazide microcapsules were prepared using sodium alginate and mucoadhesive polymer such as sodium carboxymethyl cellulose (sodium CMC), carbopol 934P or hydroxy propylmethyl cellulose (HPMC) by orifice-ionic gelation method. The microcapsules were evaluated for surface morphology and particle shape by scanning electron microscope. Microcapsules were also evaluated for their microencapsulation efficiency, in vitro wash-off mucoadhesion test, in vitro drug release and in vivo study. The microcapsules were discrete, spherical and free flowing. The microencapsulation efficiency was in the range of 65–80% and microcapsules exhibited good mucoadhesive property in the in vitro wash off test. The percentage of microcapsules adhering to tissue at pH 7.4 after 6 h varied from 12–32%, whereas the percentage of microcapsules adhering to tissue at pH 1.2 after 6 h varied from 35–68%. The drug release was also found to be slow and extended for more than 16 h. In vivo testing of the mucoadhesive microcapsules in diabetic albino rats demonstrated significant antidiabetic effect of gliclazide. The hypoglycemic effect obtained by mucoadhesive microcapsules was for more than 16 h whereas gliclazide produced an antidiabetic effect for only 10 h suggesting that mucoadhesive microcapsules are a valuable system for the long term delivery of gliclazide.     

Nucleosome positioning in relation to nucleosome spacing and DNA sequence-specific binding of a protein

Nucleosome positioning is an important mechanism for the regulation of eukaryotic gene expression. Folding of the chromatin fiber can influence nucleosome positioning, whereas similar electrostatic mechanisms govern the nucleosome repeat length and chromatin fiber folding in vitro. The position of the nucleosomes is directed either by the DNA sequence or by the boundaries created due to the binding of certain trans-acting factors to their target sites in the DNA. Increasing ionic strength results in an increase in nucleosome spacing on the chromatin assembled by the S-190 extract of Drosophila embryos. In this study, a mutant lac repressor protein R3 was used to find the mechanisms of nucleosome positioning on a plasmid with three R3-binding sites. With increasing ionic strength in the presence of R3, the number of positioned nucleosomes in the chromatin decreased, whereas the internucleosomal spacings of the positioned nucleosomes in a single register did not change. The number of the positioned nucleosomes in the chromatin assembled in vitro over different plasmid DNAs with 1-3 lac operators changed with the relative position and number of the R3-binding sites. We found that in the presence of R3, nucleosomes were positioned in the salt gradient method of the chromatin assembly, even in the absence of a nucleosome-positioning sequence. Our results show that nucleosome-positioning mechanisms are dominant, as the nucleosomes can be positioned even in the absence of regular spacing mechanisms. The protein-generated boundaries are more effective when more than one binding site is present with a minimum distance of approximately 165 bp, greater than the nucleosome core DNA length, between them.     

The Kinematics of Cytotoxic Lymphocytes Influence Their Ability to Kill Target Cells

Cytotoxic lymphocytes (CTL) have been reported to show a range of motility patterns from rapid long-range tracking to complete arrest, but how and whether these kinematics affect their ability to kill target cells is not known. Many in vitro killing assays utilize cell lines and tumour-derived cells as targets, which may be of limited relevance to the kinetics of CTL-mediated killing of somatic cells. Here, live-cell microscopy is used to examine the interactions of CTL and primary murine skin cells presenting antigens. We developed a qualitative and quantitative killing assay using extended-duration fluorescence time-lapse microscopy coupled with large-volume objective software-based data analysis to obtain population data of cell-to-cell interactions, motility and apoptosis. In vivo and ex vivo activated antigen-specific cytotoxic lymphocytes were added to primary keratinocyte targets in culture with fluorometric detection of caspase-3 activation in targets as an objective determinant of apoptosis. We found that activated CTL achieved contact-dependent apoptosis of non-tumour targets after a period of prolonged attachment – on average 21 hours – which was determined by target cell type, amount of antigen, and activation status of CTL. Activation of CTL even without engagement of the T cell receptor was sufficient to mobilise cells significantly above baseline, while the addition of cognate antigen further enhanced their motility. Highly activated CTL showed markedly increased vector displacement, and velocity, and lead to increased antigen-specific target cell death. These data show that the inherent kinematics of CTL correlate directly with their ability to kill non-tumour cells presenting cognate antigen.