Differential proteomics analysis of the surface heterogeneity of dextran iron oxide nanoparticles and the implications for their in vivo clearance

In order to understand the role of plasma proteins in the rapid liver clearance of dextran-coated superparamagnetic iron oxide (SPIO) in vivo, we analyzed the full repertoire of SPIO-binding blood proteins using novel two-dimensional differential mass spectrometry approach. The identified proteins showed specificity for surface domains of the nanoparticles: mannan-binding lectins bound to the dextran coating, histidine-rich glycoprotein and kininogen bound to the iron oxide part, and the complement lectin and contact clotting factors were secondary binders. Nanoparticle clearance studies in knockout mice suggested that these proteins, as well as several previously identified opsonins, do not play a significant role in the SPIO clearance. However, both the dextran coat and the iron oxide core remained accessible to specific probes after incubation of SPIO in plasma, suggesting that the nanoparticle surface could be available for recognition by macrophages, regardless of protein coating. These data provide guidance to rational design of bioinert, long-circulating nanoparticles.National Cancer Institute (U.S.) (Grant CA119335)National Cancer Institute (U.S.) (Grant CA124427

SynthoPlate: A platelet-inspired hemostatic nanotechnology for treatment of bleeding complications

Platelet transfusions are routinely used in the clinic to treat bleeding complications stemming from trauma, surgery, malignancy-related bone marrow dysfunctions, and congenital or drug-related defects platelet defects. These transfusions primarily use allogeneic platelet concentrates (PCs) that pose issues of limited availability and portability, high risk of bacterial contamination, very short shelf life (~3-5 days), need for antigen matching and several biologic side effects. While robust research is being directed at resolving some of these issues, there is in parallel a significant clinical interest in synthetic platelet substitutes that can render efficient hemostasis by leveraging and amplifying endogenous clotting mechanisms while avoiding the above issues. To this end, we have developed a unique platelet-inspired synthetic hemostat technology called the SynthoPlate® (US Patent 9107845). Since platelets promote primary hemostasis via adhesion to vWF and collagen at the injury site and concomitant aggregation via fibrinogen binding to integrin GPIIb-IIIa on active platelets, we have mimicked and integrated these key hemostatic mechanisms on the SynthoPlate® by heteromultivalent surface-engineering of a liposomal platform with vWF-binding peptides (VBP), collagen-binding peptides (CBP) and fibrinogen-mimetic peptides (FMP). These ~150nm diameter SynthoPlate® vesicles are sterilizable and can be stored as lyophilized powder for long periods of time. We demonstrated, in vitro, that this platelet-mimetic integrative design renders hemostatically relevant functions at levels significantly higher than designs that mimic platelet’s adhesion function only or aggregation function only. We further demonstrated in vitro that SynthoPlate®-mediated site-selective amplification of primary hemostatic mechanisms (active platelet recruitment and aggregation) in effect results in site-selective enhancement of secondary hemostatic function (fibrin generation). We also established that SynthoPlate® does not activate and aggregate resting platelets or trigger coagulation mechanisms in plasma, suggesting that this technology will not have systemic pro-thrombotic and coagulatory risks. The hemostatic efficacy of SynthoPlate® was tested in appropriate tail-transection and liver bleeding models in mice, as well as, pilot studies in arterial bleeding model in pigs. In tail-transection bleeding model in normal as well as thrombocytopenic mice, prophylactically administered SynthoPlate® was able to significantly reduce bleeding time by 60-70%. In laparotomy traumatic bleeding model in mice, prophylactically administered SynthoPlate® was able to reduce blood volume loss by ~30%, reduced hypotension effects and increased survival by \u3e80%. In pilot pig models of arterial bleeding, emergency administration of SynthoPlate® has shown substantial reduction in blood volume loss. Immunohistological evaluation of tissues from various treated animals have shown marked co-localization of red fluorescent SynthoPlate® with green fluorescent platelets localized at the clot site. Biodistribution studies in animals indicate that SynthoPlate® is cleared primarily by liver and spleen, similar to clinically known liposomal technologies. We have also demonstrated that the platelet-mimetic heteromultivalent surface-decoration approach can be adapted to other biomedically relevant particle platforms. Altogether, our studies establish the promise of SynthoPlate® nanotechnology as a platelet-mimetic intravenous hemostat for treatment of bleeding complications in prophylactic and emergency scenarios. Ongoing studies are focused on evaluating this technology in clinically motivated large animal bleeding models, with a vision for translation

Conscientiousness in the Classroom: A Process Explanation

Although the research literature has established that Conscientiousness predicts task performance across a variety of achievement contexts (e.g., Barrick & Mount, 1991; OﾒConnor & Paunonen, 2007), comparatively less is known about the processes that underlie these relations. To the latter end, the current research examines effortful strategies and achievement goals as mediating factors that might explain why people with higher levels of Conscientiousness are predicted to reach higher levels of academic performance. In a longitudinal study, 347 college students completed measures of personality and achievement goals at the beginning of the class, followed by measures of effortful strategies multiple times throughout the semester. Results support the hypothesis that effortful strategies mediate the association between Conscientiousness and academic performance. Moreover, the statistical effects of Conscientiousness were generally independent of achievement goals, but a small portion of the effect was mediated through approach, not avoidance, achievement goals. These results highlight the importance of examining mediating processes between personality and outcomes, and in the case of Conscientiousness, our results suggest that effortful strategies might serve as a useful target for performance-enhancing interventions. Intelligence and hard work are often viewed as two essential ingredients for success in achievement contexts such as school and work. Consistent with this intuition, there is a well-established literature focusing on the connections between intelligence and performance (e.g., Judge, Higgins, Thoresen, & Barrick, 1999; Schmidt & Hunter, 1998), and a more recent history of research has pointed to the importance of Conscientiousness as a predictor of job performance that is relatively independent of intelligence (e.g., Barrick & Mount, 1991; Judge et al.,1999; Judge, Klinger, Simon, & Yang, 2008; Noftle & Robins, 2007; Roberts, Kuncel, Shiner, Caspi, & Goldberg, 2007). Turning to the academic context, a recent meta-analysis found that Conscientiousness, in fact, was the only practically significant personality predictor of postsecondary performance (OﾒConnor & Paunonen, 2007). Additional research is now required to understand why Conscientiousness predicts outcomes by identifying and modeling the mediating mechanisms between Conscientiousness and academic performance outcomes. In the current study, we propose that Conscientiousness is related to the types of goals, study strategies, and work habits that in turn promote success in academic contexts. We test this proposed process-based explanation using longitudinal data collected from college students. Our perspective is informed by McAdams and Pals's (2006) integrative personality framework, which identifies three major levels of personality. The first level, dispositional traits, is probably the most dominant approach in contemporary personality psychology. This level captures ﾓbroad individual differences in behavior, thought, and feeling that account for general consistencies across situations and over timeﾔ (p. 212). The second level, characteristic adaptations, incorporates social-cognitive variables such as goals that are ﾓcontextualized in time, situations, and social rolesﾔ (p. 212). The third and most fine-grained level addresses life narratives, or the construction of life stories and the development of individual identities. Our investigation focuses on the first two levels, in that we use constructs from the achievement goal literature to help explain how Conscientiousness (a dispositional or trait construct) is linked with academic outcomes. Formulating process models that bridge these two levels provides an opportunity to develop a more integrative understanding by moving beyond the study of simple trait-to-outcome correlations in the domains of personality and educational research

Plasma kallikrein structure reveals apple domain disc rotated conformation compared to factor XI

BackgroundPlasma prekallikrein (PK) and factor XI (FXI) are apple domain‐containing serine proteases that when activated to PKa and FXIa cleave substrates kininogen, factor XII, and factor IX, respectively, directing plasma coagulation, bradykinin release, inflammation, and thrombosis pathways.ObjectiveTo investigate the three‐dimensional structure of full‐length PKa and perform a comparison with FXI.MethodsA series of recombinant full‐length PKa and FXI constructs and variants were developed and the crystal structures determined.Results and conclusionsA 1.3 Å structure of full‐length PKa reveals the protease domain positioned above a disc‐shaped assemblage of four apple domains in an active conformation. A comparison with the homologous FXI structure reveals the intramolecular disulfide and structural differences in the apple 4 domain that prevents dimer formation in PK as opposed to FXI. Two latchlike loops (LL1 and LL2) extend from the PKa protease domain to form interactions with the apple 1 and apple 3 domains, respectively. A major unexpected difference in the PKa structure compared to FXI is the 180° disc rotation of the apple domains relative to the protease domain. This results in a switched configuration of the latch loops such that LL2 interacts and buries portions of the apple 3 domain in the FXI zymogen whereas in PKa LL2 interacts with the apple 1 domain. Hydrogen‐deuterium exchange mass spectrometry on plasma purified human PK and PKa determined that regions of the apple 3 domain have increased surface exposure in PKa compared to the zymogen PK, suggesting conformational change upon activation

Factor XII and kininogen asymmetric assembly with gC1qR/C1QBP/P32 is governed by allostery

The contact system is composed of Factor XII (FXII), prekallikrein (PK) and co-factor kininogen (HK). The globular C1q receptor (gC1qR) has been shown to interact with FXII and HK. We reveal the FXII fibronectin type II domain (FnII) binds gC1qR in a Zn2+ dependent fashion and determined the complex crystal structure. FXIIFnII binds the gC1qR trimer in an asymmetric fashion with residues Arg36 and Arg65 forming contacts with two distinct negatively charged pockets. gC1qR residues Asp185 and His187 coordinate a Zn2+ adjacent to the FXII binding site and a comparison with the ligand free gC1qR crystal structure reveals the anionic G1-loop becomes ordered upon FXIIFnII binding. Additional conformational changes in the region of the Zn2+ binding site reveal an allosteric basis for Zn2+ modulation of FXII binding. Mutagenesis coupled with SPR demonstrate the gC1qR Zn2+ site contributes to FXII binding and plasma based assays reveal gC1qR stimulates coagulation in a FXII-dependent manner. Analysis of the binding of HK domain 5 (HKD5) to gC1qR shows only one high affinity binding site per trimer. Mutagenesis studies identify a critical G3-loop located at the center of the gC1qR trimer suggesting steric occlusion as the mechanism for HKD5 asymmetric binding. Gel filtration experiments reveal that gC1qR clusters FXII and HK into a higher order 500kDa ternary complex. These results support the conclusion that extracellular gC1qR can act as a chaperone to cluster contact factors which may be a prelude for initiating the cascades which drive bradykinin generation and the intrinsic pathway of coagulation

Rituximab for treatment of inhibitors in haemophilia A: A Phase II Study

The development of antibodies against infused factor VIII (FVIII) in patients with haemophilia A is a serious complication leading to poorly controlled bleeding and increased morbidity. No treatment has been proven to reduce high titre antibodies in patients who fail immune tolerance induction or are not candidates for it. The Rituximab for the Treatment of Inhibitors in Congenital Hemophilia A (RICH) study was a phase II trial to assess whether rituximab can reduce anamnestic FVIII antibody (inhibitor) titres. Male subjects with severe congenital haemophilia A and an inhibitor titre ≥5 Bethesda Units/ml (BU) following a FVIII challenge infusion received rituximab 375 mg/m2 weekly for weeks 1 through 4. Post-rituximab inhibitor titres were measured monthly from week 6 through week 22 to assess treatment response. Of 16 subjects who received at least one dose of rituximab, three (18.8%) met the criteria for a major response, defined as a fall in inhibitor titre to <5 BU, persisting after FVIII re-challenge. One subject had a minor response, defined as a fall in inhibitor titre to <5 BU, increasing to 5–10 BU after FVIII re-challenge, but <50% of the original peak inhibitor titre. Rituximab is useful in lowering inhibitor levels in patients, but its effect as a solo treatment strategy is modest. Future studies are indicated to determine the role of rituximab as an adjunctive therapy in immune tolerisation strategies

Активность микрофлоры как показатель токсичности морских донных отложений шельфовой зоны Черного моря и Керченского пролива

Изучена потенциальная активность донной микрофлоры в местах утечки остатков химических токсикантов, затопленных в период Второй Мировой войны ХХ в. Отмечены особенности восстановления жизнедеятельности микрофлоры при различных уровнях загрязнения донных отложений мышьяком и хлорированными органическими сульфидами. Полученные результаты перспективно использовать при оценке экологического состояния донных отложений в загрязненных прибрежных акваториях

Dose of Prophylactic Platelet Transfusions and Prevention of Hemorrhage

We conducted a trial of prophylactic platelet transfusions to evaluate the effect of platelet dose on bleeding in patients with hypoproliferative thrombocytopenia