Characterization of Le(x), Le(y) and A Le(y) antigen determinants in KDN-containing O-linked glycan chains from Pleurodeles waltlii jelly coat eggs.

Novel acidic oligosaccharides were isolated in large amounts by reductive alkaline treatment of the jelly coat of Pleurodeles waltlii (Michah) eggs. The oligosaccharides were found to contain the newly described KDN as acidic monosaccharide and possess either the Le(x), Le(y) and A Le(y) antigenic determinants. Occurrence of Le(x) and Le(y) determinants previously recognized as tumor-associated antigen (TAA) demonstrates that mucins of lower animals may represent a rich and easily available source for preparing TAA. Moreover, it reinforces the hypothesis according to which TAA are evolution markers.     

Platinum complexes of p- and m-aminobenzamidine. Synthesis, characterization, and cytotoxic activity.

Four platinum(II) aminobenzamidine complexes have been prepared and characterized by IR and 1H and 13C NMR spectroscopy, and tested for their ability to interact with the nicked and closed circular forms of the pUC8 plasmid DNA. The results show that the complexes of formula [Pt(LH)2Cl2]2X have a cis- geometry with an amino-Pt bonding, where L is either p- or m-aminobenzamidine and where 2X is 2Cl- or PtCl4(2-). It was observed that these complexes significantly alter the electrophoretic mobility of nicked and closed circular forms of DNA and that the alteration in electrophoretic mobility due to Pt(II)-p-aminobenzamidine binding is higher than that due to Pt(II)-m-aminobenzamidine. No difference in mobility was observed whether the DNA interacted with complexes having as counteranion Cl- or PtCl4(2-). The synthesized compounds were, in addition, assayed for antitumor activity in vitro against colon (CX-1), lung (LX-1), and mammary (MX-1) human tumor cells. The results show that these complexes inhibited the multiplication of the tumor cells and that they show higher specificity for lung cells.     

GEF-H1 Mediated Control of NOD1 Dependent NF-κB Activation by Shigella Effectors

Shigella flexneri has evolved the ability to modify host cell function with intracellular active effectors to overcome the intestinal barrier. The detection of these microbial effectors and the initiation of innate immune responses are critical for rapid mucosal defense activation. The guanine nucleotide exchange factor H1 (GEF-H1) mediates RhoA activation required for cell invasion by the enteroinvasive pathogen Shigella flexneri. Surprisingly, GEF-H1 is requisite for NF-κB activation in response to Shigella infection. GEF-H1 interacts with NOD1 and is required for RIP2 dependent NF-κB activation by H-Ala-D-γGlu-DAP (γTriDAP). GEF-H1 is essential for NF-κB activation by the Shigella effectors IpgB2 and OspB, which were found to signal in a NOD1 and RhoA Kinase (ROCK) dependent manner. Our results demonstrate that GEF-H1 is a critical component of cellular defenses forming an intracellular sensing system with NOD1 for the detection of microbial effectors during cell invasion by pathogens.     

Protein kinase D1/2 is involved in the maturation of multivesicular bodies and secretion of exosomes in T and B lymphocytes

Multivesicular bodies (MVBs) are endocytic compartments that enclose intraluminal vesicles (ILVs) formed by inward budding from the limiting membrane of endosomes. In T lymphocytes, these ILV contain Fas ligand (FasL) and are secreted as ''lethal exosomes'' following activation-induced fusion of the MVB with the plasma membrane. Diacylglycerol (DAG) and diacylglycerol kinase α (DGKα) regulate MVB maturation and polarized traffic, as well as subsequent secretion of pro-apoptotic exosomes, but the molecular basis underlying these phenomena remains unclear. Here we identify protein kinase D (PKD) family members as DAG effectors involved in MVB genesis and secretion. We show that the inducible secretion of exosomes is enhanced when a constitutively active PKD1 mutant is expressed in T lymphocytes, whereas exosome secretion is impaired in PKD2-deficient mouse T lymphoblasts and in PKD1/3-null B cells. Analysis of PKD2-deficient T lymphoblasts showed the presence of large, immature MVB-like vesicles and demonstrated defects in cytotoxic activity and in activation-induced cell death. Using pharmacological and genetic tools, we show that DGKα regulates PKD1/2 subcellular localization and activation. Our studies demonstrate that PKD1/2 is a key regulator of MVB maturation and exosome secretion, and constitutes a mediator of the DGKα effect on MVB secretory traffic.Exosomes are nanovesicles that form as intraluminal vesicles (ILVs) inside multivesicular bodies (MVBs) and are then secreted by numerous cell types.¹ ILVs are generated by inward budding of late endosome limiting membrane in a precisely regulated maturation process.^{2, 3} Two main pathways are involved in MVB maturation.^{4, 5} In addition to the ESCRT (endosomal complex required for traffic) proteins,⁶ there is increasing evidence that lipids such as lyso-bisphosphatidic acid (LBPA),⁷ ceramides⁸ and diacylglycerol (DAG)⁹ contribute to this membrane invagination process.Exosomes participate in many biological processes related to T-cell receptor (TCR)-triggered immune responses, including T lymphocyte-mediated cytotoxicity and activation-induced cell death (AICD), antigen presentation and intercellular miRNA exchange.^{10, 11, 12, 13, 14, 15} The discovery of exosome involvement in these responses increased interest in the regulation of exosome biogenesis and secretory traffic, with special attention to the contribution of lipids such as ceramide and DAG, as well as DAG-binding proteins.^{14, 16, 17, 18, 19, 20, 21} These studies suggest that positive and negative DAG regulators may control secretory traffic. By transforming DAG into phosphatidic acid (PA), diacylglycerol kinase α (DGKα) is essential for the negative control of DAG function in T lymphocytes.²² DGKα translocates transiently to the T-cell membrane after human muscarinic type 1 receptor (HM1R) triggering or to the immune synapse (IS) after TCR stimulation; at these subcellular locations, DGKα acts as a negative modulator of phospholipase C (PLC)-generated DAG.^{23, 24}The secretory vesicle pathway involves several DAG-controlled checkpoints at which DGKα may act; these include vesicle formation and fission at the trans-Golgi network (TGN), MVB maturation, as well as their transport, docking and fusion to the plasma membrane.^{9, 16, 17, 18, 19, 20} The molecular components that regulate some of these trafficking processes include protein kinase D (PKD) family members.²¹ PKD1 activity, for instance, regulates fission of transport vesicles from TGN via direct interaction with the pre-existing DAG pool at this site.¹⁹ The cytosolic serine/threonine kinases PKD1, PKD2 and PKD3^{(ref. 21)} are expressed in a wide range of cells, with PKD2 the most abundant isotype in T lymphocytes.^{25, 26} PKD have two DAG-binding domains (C1a and C1b) at the N terminus,²¹ which mediate PKD recruitment to cell membranes. Protein kinase C (PKC) phosphorylation at the PKD activation loop further promotes PKD autophosphorylation and activation.²⁷Based on our previous studies showing DGKα regulation of DAG in MVB formation and exosome secretion,^{9, 14, 28} and the identification of PKD1/2 association to MVB,¹⁴ we hypothesized that DGKα control of DAG mediates these events, at least in part, through PKD. Here we explored whether, in addition to its role in vesicle fission from TGN,¹⁹ PKD regulates other steps in the DAG-controlled secretory traffic pathway. Using PKD-deficient cell models, we analyzed the role of PKD1/2 in MVB formation and function, and demonstrate their implication in exosome secretory traffic.     

Counting Highly Cited Papers for University Research Assessment: Conceptual and Technical Issues

A Kuhnian approach to research assessment requires us to consider that the important scientific breakthroughs that drive scientific progress are infrequent and that the progress of science does not depend on normal research. Consequently, indicators of research performance based on the total number of papers do not accurately measure scientific progress. Similarly, those universities with the best reputations in terms of scientific progress differ widely from other universities in terms of the scale of investments made in research and in the higher concentrations of outstanding scientists present, but less so in terms of the total number of papers or citations. This study argues that indicators for the 1% high-citation tail of the citation distribution reveal the contribution of universities to the progress of science and provide quantifiable justification for the large investments in research made by elite research universities. In this tail, which follows a power low, the number of the less frequent and highly cited important breakthroughs can be predicted from the frequencies of papers in the upper part of the tail. This study quantifies the false impression of excellence produced by multinational papers, and by other types of papers that do not contribute to the progress of science. Many of these papers are concentrated in and dominate lists of highly cited papers, especially in lower-ranked universities. The h-index obscures the differences between higher- and lower-ranked universities because the proportion of h-core papers in the 1% high-citation tail is not proportional to the value of the h-index.     

Influence measures based on the volume of confidence ellipsoids for GEE

The generalized estimating equations (GEE) derived by Liang and Zeger to analyze longitudinal data have been used in a wide range of medical and biological applications. To make regression a useful and meaningful statistical tool, emphasis should be placed not only on inference or fitting, but also on diagnosing potential data problems. Most of the usual diagnostics for linear regression models have been generalized for GEE. However, global influence measures based on the volume of confidence ellipsoids are not available for GEE analysis. This article presents an extension of these measures that is valid for correlated‐measures regression analysis using GEEs. The proposed measures are illustrated by an analysis of epileptic seizure count data arising from a study of prograbide as an adjuvant therapy for partial seizures and some simulated data sets.