Full-length extracellular region of the var2CSA variant of PfEMP1 is required for specific,high-affinity binding to CSA

Pregnancy-associated malaria (PAM) is a serious consequence of sequestration of Plasmodium falciparum-parasitized erythrocytes (PE) in the placenta through adhesion to chondroitin sulfate A (CSA) present on placental proteoglycans. Recent work implicates var2CSA, a member of the PfEMP1 family, as the mediator of placental sequestration and as a key target for PAM vaccine development. Var2CSA is a 350 kDa transmembrane protein, whose extracellular region includes six Duffy-binding-like (DBL) domains. Due to its size and high cysteine content, the full-length var2CSA extracellular region has not hitherto been expressed in heterologous systems, thus limiting investigations to individual recombinant domains. Here we report for the first time the expression of the full-length var2CSA extracellular region (domains DBL1X to DBL6ε) from the 3D7 parasite strain using the human embryonic kidney 293 cell line. We show that the recombinant extracellular var2CSA region is correctly folded and that, unlike the individual DBL domains, it binds with high affinity and specificity to CSA (K_D = 61 nM) and efficiently inhibits PE from binding to CSA. Structural characterization by analytical ultracentrifugation and small-angle x-ray scattering reveals a compact organization of the full-length protein, most likely governed by specific interdomain interactions, rather than an extended structure. Collectively, these data suggest that a high-affinity, CSA-specific binding site is formed by the higher-order structure of the var2CSA extracellular region. These results have important consequences for the development of an effective vaccine and therapeutic inhibitors.     

Composite microparticles with in vivo reduction of the burst release effect

The aim of this study was to develop microparticles containing nanoparticles (composite microparticles) for prolonged drug delivery with reduced burst effect in vitro and in vivo. Such composite microparticles were prepared with hydrophobic and biodegradable polymers [poly(ε-caprolactone), poly(lactic-co-glycolic) acid]. Ibuprofen was chosen as the model drug, and microparticles were prepared by the extraction technique with ethyl acetate as the solvent. Nanoparticles and microparticles and an ibuprofen solution (Pedea^®) were administered subcutaneously at the dose of 1 mg of ibuprofen per kg to overnight-fasted rats (male Wistar). Composite microparticles showed prolonged ibuprofen release and less burst effect when compared to simple microparticles (without nanoparticles inside) or nanoparticles both in vitro (PBS buffer) and in vivo. Moreover, ibuprofen was still detected in the plasma after 96 h with composite microparticles. Consequently, it has been demonstrated that composite microparticles were able to reduce burst release and prolong the release of ibuprofen for a long period of time.     

Accumulation and Depuration of Trace Metals in Southern Toads, Bufo terrestris, Exposed to Coal Combustion Waste

Accumulation and depuration of metals by an organism are underrepresented in the literature. We collected southern toads (Bufo terrestris) from coal by-product (ash)-contaminated and uncontaminated sites to examine metal concentrations over time. Toads were placed in four exposure regimes, then sacrificed periodically over a 5-month period, and whole-body metal levels were measured. Toads exposed to ash accumulated significant concentrations of metals. Metal concentrations changed throughout the experiment, and profiles of accumulation and depuration differed depending on the metal and exposure regime. Ash-exposed toads exhibited elevated levels of 11 of 18 metals measured. Increases ranged from 47.5% for Pb to more than 5000% for As. Eight of 18 metals did not change in control toads, while 10 of 18 metals decreased in toads removed from ash, ranging from −25% for Co to −96% for Tl. Seven metals that decreased in toads removed from ash did not change in control toads.     

From the family universe to the outside world: Family relations, school attitude, and perception of racism in Caribbean and Filipino adolescents

Caribbean and Filipino immigrant families in Canada have much in common: the women have often immigrated as domestic workers, first-generation children may be separated from their parents for long periods, and they must deal with negative stereotypes of their ethnic group. This transcultural study looks at the associations between family relations and adolescents’ perceptions of both their own group and the host society, and analyzes how these affect their mental health. The results suggest that family cohesion plays a key role in shaping adolescents’ perceptions of racism in the host country and in promoting a positive appraisal of their own community, thus highlighting the need for a systemic understanding of family and intergroup relations.     

Fluorinated 1,2,4‐Triazolo[1,5‐a]pyrimidine‐6‐carboxylic Acid Derivatives as Antimycobacterial Agents

A series of fluorinated 1,2,4‐triazolo[1,5‐a]pyrimidine‐6‐carboxylic acid derivatives was designed and synthesized as fluoroquinolone analogues. The synthesized compounds were screened against Mycobacterium tuberculosis H₃₇R_v strain at 6.25 μg/mL concentration. Compound 4 , the 7‐oxo‐2‐(trifluoromethyl)‐4,7‐dihydro‐1,2,4‐triazolo[5,1‐a]pyrimidine‐6‐carboxylic acid was found to be a very potent inhibitor, being able to inhibit 92% growth of M. tuberculosis H₃₇R_v at 6.25 μg/mL concentration. At the same time, it proofed to be nontoxic to mammalian cells (IC₅₀ > 62.5 μg/mL in VERO cells).     

Investigation of the mechanisms involved in the high-dose and long-term acetyl salicylic acid therapy of type I diabetic rats

Diabetes mellitus has been classified as a conformational disease because of changes induced in the structure and function of proteins due to hyperglycemia. In this study, we investigated the effect of high-dose and long-term use of acetyl salicylic acid (ASA) on the streptozotocin-induced diabetic rats as a model of type I diabetes, with consideration on the structure and/or function of proteins. The N-[methylnitrosocarbamoyl]-d-glucosamine (streptozotocin)-induced diabetic rats together with the normal rats were studied for 5 months with and without receiving 100 mg/kg ASA in drinking water. All rats were investigated from different aspects such as heat shock protein (HSP) 70 level, serum glucose and insulin concentration, advanced glycated end product (AGE) and glycated hemoglobin (HbA1c) formation, lipid profile, high-density lipoprotein (HDL) functionality (paraoxonase1 and lecithin cholesterol acyltransferase activities), and the antioxidant system. In addition, the in vitro effect of ASA on the structure of albumin as a model protein was studied in the presence of glucose by spectroscopic techniques such as fluorometry and circular dichroism. The results show that ASA therapy causes a decrease in the glucose level and AGE and HbA1c formation, improves the lipid profile, HDL functionality, and the antioxidant capacity, induces serum HSP70, and overall decreases mortality of diabetic rats in comparison with the group without treatment. The conformation of glycated bovine serum albumin is different from the native form, and ASA retains the conformation of this protein similar to the native. The improving effect of ASA on diabetic rats is mostly due to its role as a chemopreventive agent in the structural conservation and protection of proteins involved in diabetes pathogenesis.     

Evaluation of the local anaesthetic activity of 3-aminobenzo[d]isothiazole derivatives using the rat sciatic nerve model

On the basis of computer prediction of biological activity by PASS and toxicity by DEREK, the most promising 32-alkylaminoacyl derivatives of 3-aminobenzo[d]isothiazole were selected for possible local anaesthetic action. This action was evaluated using an in vitro preparation of the isolated sciatic nerve of the rat and compared with lidocaine which was used as a reference compound. QSAR studies showed that the polarizability, polarity and molecular shape of molecules have a positive influence on their local anaesthetic activity, while contributions of aromatic CH and singly bonded nitrogen are negative. Since the estimated PASS probabilities to find local anaesthetic activity in the most active compounds are less than 50%, these compounds may be considered to be possible NCEs.