Salivary histatin 5 internalization by translocation, but not endocytosis, is required for fungicidal activity in Candida albicans

Salivary histatin 5 (Hst 5) is a cationic salivary protein with high fungicidal activity against Candida albicans. Binding to the cell wall followed by intracellular translocation is required for killing; however, specific binding components and critical toxic events are not understood. In this study, laminarin (β-1,3-glucan) but not sialic acid, mannan or pustulan mediated Hst 5 binding to C. albicans, and was disassociated by 100 mM NaCl. Time-lapse confocal microscopy revealed a dose-dependent rate of cytosolic uptake of Hst 5 that invariably preceded propidium iodide (PI) entry, demonstrating that translocation itself does not disrupt membrane integrity. Cell toxicity was manifest by vacuolar expansion followed by PI entrance; however, loss of endocytotic vacuolar trafficking of Hst 5 did not reduce killing. Extracellular NaCl (100 mM), but not sorbitol, prevented vacuolar expansion and PI entry in cells already containing cytosolic Hst 5, thus showing a critical role for ionic balance in Hst 5 toxicity. Hst 5 uptake, but not cell wall binding, was blocked by pretreatment with azide or carbonyl cyanide m-chlorophenylhydrazone; however, 10% of de-energized cells had membrane disruption. Thus, Hst 5 is capable of heterogeneous intracellular entry routes, but only direct cytosolic translocation causes cell death as a result of ionic efflux

ATP release via anion channels

ATP serves not only as an energy source for all cell types but as an ‘extracellular messenger-for autocrine and paracrine signalling. It is released from the cell via several different purinergic signal efflux pathways. ATP and its Mg2+ and/or H+ salts exist in anionic forms at physiological pH and may exit cells via some anion channel if the pore physically permits this. In this review we survey experimental data providing evidence for and against the release of ATP through anion channels. CFTR has long been considered a probable pathway for ATP release in airway epithelium and other types of cells expressing this protein, although non-CFTR ATP currents have also been observed. Volume-sensitive outwardly rectifying (VSOR) chloride channels are found in virtually all cell types and can physically accommodate or even permeate ATP4- in certain experimental conditions. However, pharmacological studies are controversial and argue against the actual involvement of the VSOR channel in significant release of ATP. A large-conductance anion channel whose open probability exhibits a bell-shaped voltage dependence is also ubiquitously expressed and represents a putative pathway for ATP release. This channel, called a maxi-anion channel, has a wide nanoscopic pore suitable for nucleotide transport and possesses an ATP-binding site in the middle of the pore lumen to facilitate the passage of the nucleotide. The maxi-anion channel conducts ATP and displays a pharmacological profile similar to that of ATP release in response to osmotic, ischemic, hypoxic and salt stresses. The relation of some other channels and transporters to the regulated release of ATP is also discussed

Neuroprotection by adenosine in the brain: From A1 receptor activation to A2A receptor blockade

Adenosine is a neuromodulator that operates via the most abundant inhibitory adenosine A1 receptors (A1Rs) and the less abundant, but widespread, facilitatory A2ARs. It is commonly assumed that A1Rs play a key role in neuroprotection since they decrease glutamate release and hyperpolarize neurons. In fact, A1R activation at the onset of neuronal injury attenuates brain damage, whereas its blockade exacerbates damage in adult animals. However, there is a down-regulation of central A1Rs in chronic noxious situations. In contrast, A2ARs are up-regulated in noxious brain conditions and their blockade confers robust brain neuroprotection in adult animals. The brain neuroprotective effect of A2AR antagonists is maintained in chronic noxious brain conditions without observable peripheral effects, thus justifying the interest of A2AR antagonists as novel protective agents in neurodegenerative diseases such as Parkinson’s and Alzheimer’s disease, ischemic brain damage and epilepsy. The greater interest of A2AR blockade compared to A1R activation does not mean that A1R activation is irrelevant for a neuroprotective strategy. In fact, it is proposed that coupling A2AR antagonists with strategies aimed at bursting the levels of extracellular adenosine (by inhibiting adenosine kinase) to activate A1Rs might constitute the more robust brain neuroprotective strategy based on the adenosine neuromodulatory system. This strategy should be useful in adult animals and especially in the elderly (where brain pathologies are prevalent) but is not valid for fetus or newborns where the impact of adenosine receptors on brain damage is different

The relationship between the Test of English as a Foreign Language (TOEFL), the International English Language Testing System (IELTS) scores and academic success of international Master's students

The purpose of this study was to examine if the Test of English as a Foreign Language (TOEFL) and the International English Language Testing System (IELTS) are related to academic success defined by final cumulative grade point average (GPA). The data sample, from three Midwestern universities, was comprised of international graduate students who graduated within 2006-2011. The total number of students records utilized were 793 (35.7% were female and 65.3% were male). The study did not find a significant difference between TOEFL (paper-based, computer-based, and internet-based) and IELTS scores in relation to academic success. Students tended to score higher on TOEFL iBT followed by TOEFL PBT. Indian and Taiwanese students performed better on TOEFL iBT and Chinese and Indian students performed better on the TOEFL PBT. A statistical significance was found among final cumulative GPA and college program of study in relation to TOEFL and IELTS scores. Knowing more about the reasons behind international graduate students' academic success is a benefit to institutions. The findings of this study may help graduate offices in comprehensive Midwestern institutions, with the recruitment and retention of international students. The research may also assist in the evaluation of admission requirements

Relationship between the Test of English as a Foreign Language (TOEFL), the International English Language Testing System (IELTS) scores and academic success of international master's students, The

2013 Spring.Includes bibliographical references.The purpose of this study was to examine if the Test of English as a Foreign Language (TOEFL) and the International English Language Testing System (IELTS) are related to academic success defined by final cumulative grade point average (GPA). The data sample, from three Midwestern universities, was comprised of international graduate students who graduated within 2006-2011. The total number of students records utilized were 793 (35.7% were female and 65.3% were male). The study did not find a significant difference between TOEFL (paper-based, computer-based, and internet-based) and IELTS scores in relation to academic success. Students tended to score higher on TOEFL iBT followed by TOEFL PBT. Indian and Taiwanese students performed better on TOEFL iBT and Chinese and Indian students performed better on the TOEFL PBT. A statistical significance was found among final cumulative GPA and college program of study in relation to TOEFL and IELTS scores. Knowing more about the reasons behind international graduate students' academic success is a benefit to institutions. The findings of this study may help graduate offices in comprehensive Midwestern institutions, with the recruitment and retention of international students. The research may also assist in the evaluation of admission requirements

BIOACTIVE SELF-FORMING HYDROGELS FOR BIOMEDICAL APPLICATIONS

Hydrogels are soft biomaterials that feature a wide range of physical and biochemical properties. Although highly versatile, hydrogels typically require an exogeneous input (e.g., light, pH, temperature) to form, and this limits their use to conditions where a catalyst is present. The goal of this dissertation is to expand the use of catalyst-based hydrogels by developing hydrogels with independently tunable properties which gel in situ without external stimuli. This new class of hydrogels was developed by first modifying macromers with norbornene (Nor) or tetrazine (Tet) moieties. Macromers containing Nor or Tet remain liquid when dissolved, and upon mixing self-form into Nor-Tet hydrogels. Hydrogels with broad mechanical properties are obtained, and peptide functionalization has no effect on mechanics or gelation time. Nor-Tet hydrogels functionalized with adhesive RGD peptides exhibit exceptional cell-matrix interactions, and stem cells in Nor-Tet solutions are protected from shear forces cells experience during liquid cell injections. Nor-Tet hydrogels functionalized with peptides containing active motifs of bone morphogenetic protein 2 (BMP2) also induce 3D osteogenic differentiation, and BMP2 Nor-Tet hydrogel injections into medullary cavities result in nascent trabecular bone growth in femurs. Taken together, the self-forming Nor-Tet hydrogels developed can be used to safely deliver cells in vivo and can serve as a targeted therapeutic to locally treat degenerative musculoskeletal diseases including osteoporosis

Green maintainability design criteria for nanostructured titanium dioxide (TiO2) façade coatings

10.1108/IJBPA-01-2017-0001International Journal of Building Pathology and Adaptation352139-15