6 research outputs found
Viscosity-Reducing Bulky-Salt Excipients Prevent Gelation of Protein, but Not Carbohydrate, Solutions
No full textThe problem of gelation of concentrated protein solutions, which poses challenges for both downstream protein processing and liquid formulations of pharmaceutical proteins, is addressed herein by employing previously discovered viscosity-lowering bulky salts. Procainamide-HCl and the salt of camphor-10-sulfonic acid with l-arginine (CSA-Arg) greatly retard gelation upon heating and subsequent cooling of the model proteins gelatin and casein in water: Whereas in the absence of additives the proteins form aqueous gels within several hours at room temperature, procainamide-HCl for both proteins and also CSA-Arg for casein prevent gel formation for months under the same conditions. The inhibition of gelation by CSA-Arg stems exclusively from the CSA moiety: CSA-Na was as effective as CSA-Arg, while Arg-HCl was marginally or not effective. The tested bulky salts did not inhibit (and indeed accelerated) temperature-induced gel formation in aqueous solutions of all examined carbohydrates―starch, agarose, alginate, gellan gum, and carrageenan. Keywords: Carbohydrates, Downstream processing of biologics, Gel formation, Hydrophobic salts, Intermolecular interactions in solution, Protein
Exploring the Behavior of Bovine Serum Albumin in Response to Changes in the Chemical Composition of Responsive Polymers: Experimental and Simulation Studies
No full textKnowledge of the interactions between polymer and protein is very important to fabricate the potential materials for many bio-related applications. In this regard, the present work investigated
the effect of copolymers on the conformation and thermal stability of bovine serum albumin (BSA) with the aid of biophysical techniques such as fluorescence spectroscopy, circular dichroism (CD) spectroscopy and differential scanning calorimetry (DSC). In comparison with that of copolymer PGA-1.5, our fluorescence spectroscopy results reveal that the copolymer PGA-1, which has a lower PEGMA/AA ratio, shows greater influence on the conformation of BSA. Copolymers induced
unfolding of the polypeptide chain of BSA, which was confirmed from the loss in the negative ellipticity of CD spectra. DSC results showed that the addition of PGA-1 and PGA-1.5 (0.05% (w/v) decreased the transition temperature by 14.8 and 11.5 ˝C, respectively). The results from the present study on the behavior of protein in response to changes in the chemical composition of synthetic polymers are significant for various biological applications such as enzyme immobilization, protein
separations, sensor development and stimuli-responsive systems.Feng Chia UniversityTaichung Veterans General Hospital (Contract TCVGH-FCU1048201
Mentorship for operational research capacity building: hands-on or hands-off?
No full textMentorship is a key feature of operational research training courses run by the International Union Against Tuberculosis and Lung Disease and Médecins Sans Frontières. During the recent South Pacific paper writing module, the faculty discussed ‘hands-on’ mentorship (direct technical assistance) vs. ‘hands-off’ mentorship (technical advice). This article explores the advantages and disadvantages of each approach. Our collective experience indicates that ‘hands-on’ mentorship is a valuable learning experience for the participant and a rewarding experience for the mentor. This approach increases the likelihood of successful course completion, including publishing a well written paper. However, mentors must allow participants to lead and take ownership of the paper, in keeping with a first author positio
Bradykinin B2 receptors of dendritic cells, acting as sensors of kinins proteolytically released by Trypanosoma cruzi, are critical for the development of protective type-1 responses
No full textAlthough the concept that dendritic cells (DCs) recognize pathogens through the engagement of Toll-like receptors is widely accepted, we recently suggested that immature DCs might sense kinin-releasing strains of Trypanosoma cruzi through the triggering of G-protein-coupled bradykinin B2 receptors (B2R). Here we report that C57BL/6.B2R-/- mice infected intraperitoneally with T. cruzi display higher parasitemia and mortality rates as compared to B2R+/+ mice. qRT-PCR revealed a 5-fold increase in T. cruzi DNA (14 d post-infection [p.i.]) in B2R-/- heart, while spleen parasitism was negligible in both mice strains. Analysis of recall responses (14 d p.i.) showed high and comparable frequencies of IFN-gamma-producing CD4+ and CD8+ T cells in the spleen of B2R-/- and wild-type mice. However, production of IFN-gamma by effector T cells isolated from B2R-/- heart was significantly reduced as compared with wild-type mice. As the infection continued, wild-type mice presented IFN-gamma-producing (CD4+CD44+ and CD8+CD44+) T cells both in the spleen and heart while B2R-/- mice showed negligible frequencies of such activated T cells. Furthermore, the collapse of type-1 immune responses in B2R-/- mice was linked to upregulated secretion of IL-17 and TNF-alpha by antigen-responsive CD4+ T cells. In vitro analysis of tissue culture trypomastigote interaction with splenic CD11c+ DCs indicated that DC maturation (IL-12, CD40, and CD86) is controlled by the kinin/B2R pathway. Further, systemic injection of trypomastigotes induced IL-12 production by CD11c+ DCs isolated from B2R+/+ spleen, but not by DCs from B2R-/- mice. Notably, adoptive transfer of B2R+/+ CD11c+ DCs (intravenously) into B2R-/- mice rendered them resistant to acute challenge, rescued development of type-1 immunity, and repressed TH17 responses. Collectively, our results demonstrate that activation of B2R, a DC sensor of endogenous maturation signals, is critically required for development of acquired resistance to T. cruzi infection. Author Summary: Antibodies and IFN-gamma-producing effector T cells are essential for the immune control of infection by Trypanosoma cruzi, the intracellular protozoa that causes human Chagas disease. Despite the potency of anti-parasite immunity, the parasites are not cleared from their intracellular niches. Instead, a low grade chronic infection prevails, provoking severe immunopathology in the myocardium. Although it is well established that innate sentinel cells sense T. cruzi through receptors for microbial structures, such as Toll-like receptors, it remained unclear whether endogenous inflammatory signals also contribute to the development of adaptive immunity. The present study was motivated by awareness that T. cruzi trypomastigotes (extracellular infective forms) are equipped with proteases that liberate the pro-inflammatory bradykinin peptide from an internal segment of kininogens. Here we demonstrate that splenic dendritic cells (DCs), the antigen-presenting cells that coordinate the adaptive branch of immunity in lymphoid tissues, are potently activated via G-protein-coupled bradykinin B2 receptors (B2R). Analysis of the outcome of infection in B2R-knockout mice revealed that the mutant mice developed a typical susceptible phenotype, owing to impaired development of IFN-gamma-producing effector T cells. Notably, the immune dysfunction of B2R-knockout mice was corrected upon cell transfer of wild-type DCs, thus linking development of protective T cells to DCs' sensing of endogenous danger signals (kinins) released by trypomastigotes
Biochar potentially enhances maize tolerance to arsenic toxicity by improving physiological and biochemical responses to excessive arsenate
No full text© 2023, The Author(s). cc-byMetalloid pollution, including arsenic poisoning, is a serious environmental issue, plaguing plant productivity and quality of life worldwide. Biochar, a carbon-rich material, has been known to alleviate the negative effects of environmental pollutants on plants. However, the specific role of biochar in mitigating arsenic stress in maize remains relatively unexplored. Here, we elucidated the functions of biochar in improving maize growth under the elevated level of sodium arsenate (Na2AsO4, AsV). Maize plants were grown in pot-soils amended with two doses of biochar (2.5% (B1) and 5.0% (B2) biochar Kg−1 of soil) for 5 days, followed by exposure to Na2AsO4 ('B1 + AsV'and 'B2 + AsV') for 9 days. Maize plants exposed to AsV only accumulated substantial amount of arsenic in both roots and leaves, triggering severe phytotoxic effects, including stunted growth, leaf-yellowing, chlorosis, reduced photosynthesis, and nutritional imbalance, when compared with control plants. Contrariwise, biochar addition improved the phenotype and growth of AsV-stressed maize plants by reducing root-to-leaf AsV translocation (by 46.56 and 57.46% in ‘B1 + AsV’ and ‘B2 + AsV’ plants), improving gas-exchange attributes, and elevating chlorophylls and mineral levels beyond AsV-stressed plants. Biochar pretreatment also substantially counteracted AsV-induced oxidative stress by lowering reactive oxygen species accumulation, lipoxygenase activity, malondialdehyde level, and electrolyte leakage. Less oxidative stress in ‘B1 + AsV’ and ‘B2 + AsV’ plants likely supported by a strong antioxidant system powered by biochar-mediated increased activities of superoxide dismutase (by 25.12 and 46.55%), catalase (51.78 and 82.82%), and glutathione S-transferase (61.48 and 153.83%), and improved flavonoid levels (41.48 and 75.37%, respectively). Furthermore, increased levels of soluble sugars and free amino acids also correlated with improved leaf relative water content, suggesting a better osmotic acclimatization mechanism in biochar-pretreated AsV-exposed plants. Overall, our findings provided mechanistic insight into how biochar facilitates maize’s active recovery from AsV-stress, implying that biochar application may be a viable technique for mitigating negative effects of arsenic in maize, and perhaps, in other important cereal crops. Graphical Abstract: [Figure not available: see fulltext.
