Enhanced viability of probiotic Saccharomyces boulardii encapsulated by layer-by-layer approach in pH responsive chitosan-dextran sulfate polyelectrolytes

Saccharomyces boulardii was encapsulated by layer-by-layer technique (LbL) using oppositely charged polyelectrolytes, chitosan and dextran sulfate to protect from degradation during its gastrointestinal transit. The protective effect of the coating was evaluated by checking viability after subjecting the coated cells to lyophilisation and simulated gastrointestinal conditions. During lyophilization, coated S. boulardii was found to have an enhanced viability of 7.74 +/- 2.00 log CFU/100 mg (5.62 x 10(6) +/- 2.12 CFU/100 mg) and 5.53 +/- 1.85 log CFU/100 mg (3.46 x 10(5) 1.73 CFU/100 mg) for uncoated cells. On sequential treatment with simulated gastric and intestinal juice, the coated cells had a viability of 4.59 +/- 1.52 log CFU/100 mg (3.8 x 104 +/- 1.52 CFU/100 mg) while only 1.90 +/- 0.80 log CFU/100 mg (0.79 x 102 +/- 0.81 CFU/100 mg) of uncoated cells survived. Confocal studies displayed the selective permeability of the coated cells which plays a significant role in maintaining the integrity and viability of the yeast cells. This clearly indicates that LbL is an efficient protective encapsulation technique and it could be potentially used for improving therapeutic applications of yeast. (C) 2014 Elsevier Ltd. All rights reserved.

Progress in tuberculosis vaccine development and host-directed therapies-a state of the art review

Tuberculosis continues to kill 1.4 million people annually. During the past 5 years, an alarming increase in the number of patients with multidrug-resistant tuberculosis and extensively drug-resistant tuberculosis has been noted, particularly in eastern Europe, Asia, and southern Africa. Treatment outcomes with available treatment regimens for drug-resistant tuberculosis are poor. Although substantial progress in drug development for tuberculosis has been made, scientific progress towards development of interventions for prevention and improvement of drug treatment outcomes have lagged behind. Innovative interventions are therefore needed to combat the growing pandemic of multidrug-resistant and extensively drug-resistant tuberculosis. Novel adjunct treatments are needed to accomplish improved cure rates for multidrug-resistant and extensively drug-resistant tuberculosis. A novel, safe, widely applicable, and more effective vaccine against tuberculosis is also desperately sought to achieve disease control. The quest to develop a universally protective vaccine for tuberculosis continues. So far, research and development of tuberculosis vaccines has resulted in almost 20 candidates at different stages of the clinical trial pipeline. Host-directed therapies are now being developed to refocus the anti-Mycobacterium tuberculosis-directed immune responses towards the host; a strategy that could be especially beneficial for patients with multidrug-resistant tuberculosis or extensively drug-resistant tuberculosis. As we are running short of canonical tuberculosis drugs, more attention should be given to host-directed preventive and therapeutic intervention measures.

Pulsed rf magnetron sputtered alumina thin films

Alumina thin films were deposited on titanium (Ti) and fused quartz by both direct and reactive pulsed rf magnetron sputtering techniques. X-ray diffraction, field emission scanning electron microscopy, energy dispersive X-ray spectroscopy and atomic force microscopy were utilized to study the phases and surface morphology of the films. The as-deposited alumina thin films were amorphous. However, after annealing at 500 degrees C in vacuum, the crystalline peaks corresponding to the Theta (0), Delta (8) and Chi ()) alumina phases were obtained. The optical transmittance and reflectance as well as IR emittanc,e data were also evaluated for the thin films. The transmittance, e.g., (similar to 90%) of the bare quartz substrate was not changed even when the alumina thin films were deposited for an hour. However, further increase in deposition time (e.g., 7 h) of the alumina thin films showed only a marginal decrease (e.g., similar to 5%) in average transmittance of the bare quartz substrate. The direct and indirect optical band gaps and extinction coefficient of the alumina films were estimated from the transmittance spectra. The IR emittance of the Ti substrate (e.g., similar to 16%) was almost constant after depositing alumina thin films for an hour. Further increase in deposition time showed only a marginal increase (e.g., similar to 9%) in IR emittance value. Therefore, it is proposed that the alumina films developed in the present work can act as a protective cover for the Ti substrate while retaining the thermo-optical properties of the same. The nanohardness and Young's modulus of the alumina thin films were evaluated by the novel nanoindentation technique. The nanohardness was measured as similar to 6 GPa. Further, Young's modulus was evaluated as similar to 116 GPa. The magnitudes of the nanomechanical properties of the thin films were a little smaller than those reported in the literature. This was linked to the lack of crystalline phases in the as-deposited alumina thin films. (C) 2014 Elsevier Ltd and Techna Group S.r.l. All rights reserved.

Context dependency of rewards and services in an Indian ant-plant interaction: southern sites favour the mutualism between plants and ants

Protection-based ant-plant mutualisms may vary in strength due to differences in ant rewards, abundance of protective ants and herbivory pressure. We investigated geographical and temporal variation in host plant traits and herbivory pressure at five sites spanning the distribution range of the myrmecophyte Humboldtia brunonis (Fabaceae) in the Indian Western Ghats. Southern siteshad, onaverage, 2.4 times greater abundance of domatia-bearing individuals, 1.6 times greater extrafloral nectary numbers per leaf, 1.2 times larger extrafloral nectary sizes, 2.2 times greater extrafloral nectar (EFN) volumes and a two-fold increase in total amino acid and total sugar concentrations in EFN compared with northern sites. Astrong protection-based mutualismwith ants occurred at only one southern site where herbivory was highest, suggesting that investments in attracting ants correlate with anti-herbivore benefits gained from the presence of protective ants. Our results confirm a temporally stable north-south gradient in myrmecophytic traits in this ant-plant as several of these traits were re-sampled after a 5-y interval. However, the chemical composition of EFN varied at both spatial and short-term temporal scales suggesting that only repeated measurements of rewards such as EFN can reveal the real spectrum of trait variation in an ant-plant mutualistic system.

Haloarchaeal gas vesicle nanoparticles displaying Salmonella SopB antigen reduce bacterial burden when administered with live attenuated bacteria

Innovative vaccines against typhoid and other Salmonella diseases that are safe, effective, and inexpensive are urgently needed. In order to address this need, buoyant, self-adjuvating gas vesicle nanoparticles (GVNPs) from the halophilic archaeon Halobacterium sp. NRC-1 were bioengineered to display the highly conserved Salmonella enterica antigen SopB, a secreted inosine phosphate effector protein injected by pathogenic bacteria during infection into the host cell. Two highly conserved sopB gene segments near the 3'-coding region, named sopB4 and B5, were each fused to the gvpC gene, and resulting GVNPs were purified by centrifugally accelerated flotation. Display of SopB4 and B5 antigenic epitopes on GVNPs was established by Western blotting analysis using antisera raised against short synthetic peptides of SopB. Immunostimulatory activities of the SopB4 and B5 nanoparticles were tested by intraperitoneal administration of recombinant GVNPs to BALB/c mice which had been immunized with S. enterica serovar Typhimurium 14028 Delta pmrG-HM-D (DV-STM-07), a live attenuated vaccine strain. Proinflammatory cytokines IFN-gamma, IL-2, and IL-9 were significantly induced in mice boosted with SopB5-GVNPs, consistent with a robust Th1 response. After challenge with virulent S. enterica serovar Typhimurium 14028, bacterial burden was found to be diminished in spleen of mice boosted with SopB4-GVNPs and absent or significantly diminished in liver, mesenteric lymph node, and spleen of mice boosted with SopB5-GVNPs, indicating that the C-terminal portions of SopB displayed on GVNPs elicit a protective response to Salmonella infection in mice. SopB antigen-GVNPs were found to be stable at elevated temperatures for extended periods without refrigeration in Halobacterium cells. The results all together show that bioengineered GVNPs are likely to represent a valuable platform for the development of improved vaccines against Salmonella diseases. (C) 2014 Elsevier Ltd. All rights reserved.

Nutritional benefits from domatia inhabitants in an ant-plant interaction: interlopers do pay the rent

1. How a symbiosis originates and is maintained are important evolutionary questions. Symbioses in myrmecophytes (plants providing nesting for ants) are believed to be maintained by protection and nutrients provided by specialist plant-ants in exchange for nesting spaces (called domatia) and nourishment offered by ant-plants. However, besides the benefits accrued from housing protective ants, the mechanisms contributing to the fitness advantages of bearing domatia have rarely been examined, especially because the domatia trait is usually constitutively expressed, and many myrmecophytes have obligate mutualisms with single ant species resulting in invariant conditions. 2. In the unspecialized ant-plant Humboldtia brunonis (Fabaceae) that offers extrafloral nectar to ants, only some plants produce domatia in the form of hollow internodes. These domatia have a self-opening slit making them more prone to interlopers and are occupied mostly by non-protective ants and other invertebrates, especially arboreal earthworms. The protection mutualism with ants is restricted in geographical extent, occurring only at a few sites in the southernmost part of this plant's range in the Western Ghats of India. 3. We examined nutrient flux from domatia residents to the plant using stable isotopes. We found that between 9% (earthworms) and 17% (protective or non-protective ants) of nitrogen of plant tissues nearest the domatium came from domatia inhabitants. Therefore, interlopers such as earthworms and non-protective ants contributed positively to the nitrogen budget of localized plant modules of this understorey tree. N-15-enriched feeding experiments with protective ants demonstrated that nutrients flowed from domatia inhabitants to nearby plant modules. Fruit set did not differ between paired hand-pollinated inflorescences on domatia and non-domatia bearing branches. This was possibly due to the nutrient flux from domatia to adjacent branches without domatia within localized modules. 4. This study has demonstrated the nutritive role of non-protective ants and non-ant invertebrates, hitherto referred to as interlopers, in an unspecialized myrmecophyte. Our study suggests that even before the establishment of a specialized ant-plant protection mutualism, nutritional benefits conferred by domatia inhabitants can explain the fitness benefits of bearing domatia, and thus the maintenance of a trait that facilitates the establishment of a specialized ant-plant symbiosis.

Adaptive evolution of a novel avian-origin influenza A/H7N9 virus

In China, the recent outbreak of novel influenza A/H7N9 virus has been assumed to be severe, and it may possibly turn brutal in the near future. In order to develop highly protective vaccines and drugs for the A/H7N9 virus, it is critical to find out the selection pressure of each amino acid site. In the present study, six different statistical methods consisting of four independent codon-based maximum likelihood (CML) methods, one hierarchical Bayesian (HB) method and one branch-site (BS) method, were employed to determine if each amino acid site of A/H7N9 virus is under natural selection pressure. Functions for both positively and negatively selected sites were inferred by annotating these sites with experimentally verified amino acid sites. Comprehensively, the single amino acid site 627 of PB2 protein was inferred as positively selected and it function was identified as a T-cell epitope (TCE). Among the 26 negatively selected amino acid sites of PB2, PB1, PA, HA, NP, NA, M1 and NS2 proteins, only 16 amino acid sites were identified to be involved in TCEs. In addition, 7 amino acid sites including, 608 and 609 of PA, 480 of NP, and 24, 25, 109 and 205 of M1, were identified to be involved in both B-cell epitopes (BCEs) and TCEs. Conversely, the function of positions 62 of PA, and, 43 and 113 of HA was unknown. In conclusion, the seven amino acid sites engaged in both BCEs and TCEs were identified as highly suitable targets, as these sites will be predicted to play a principal role in inducing strong humoral and cellular immune responses against A/H7N9 virus. (C) 2014 Elsevier Inc. All rights reserved.

Mycobacterium tuberculosis has diminished capacity to counteract redox stress induced by elevated levels of endogenous superoxide

Mycobacterium tuberculosis (Mtb) has evolved protective and detoxification mechanisms to maintain cytoplasmic redox balance in response to exogenous oxidative stress encountered inside host phagocytes. In contrast, little is known about the dynamic response of this pathogen to endogenous oxidative stress generated within Mtb. Using a noninvasive and specific biosensor of cytoplasmic redox state of Mtb, we for first time discovered a surprisingly high sensitivity of this pathogen to perturbation in redox homeostasis induced by elevated endogenous reactive oxygen species (ROS). We synthesized a series of hydroquinone-based small molecule ROS generators and found that ATD-3169 permeated mycobacteria to reliably enhance endogenous ROS including superoxide radicals. When Mtb strains including multidrug-resistant (MDR) and extensively drug-resistant (XDR) patient isolates were exposed to this compound, a dose-dependent, long-lasting, and irreversible oxidative shift in intramycobacterial redox potential was detected. Dynamic redox potential measurements revealed that Mtb had diminished capacity to restore cytoplasmic redox balance in comparison with Mycobacterium smegmatis (Msm), a fast growing nonpathogenic mycobacterial species. Accordingly, Mtb strains were extremely susceptible to inhibition by ATD-3169 but not Msm, suggesting a functional linkage between dynamic redox changes and survival. Microarray analysis showed major realignment of pathways involved in redox homeostasis, central metabolism, DNA repair, and cell wall lipid biosynthesis in response to ATD-3169, all consistent with enhanced endogenous ROS contributing to lethality induced by this compound. This work provides empirical evidence that the cytoplasmic redox poise of Mtb is uniquely sensitive to manipulation in steady-state endogenous ROS levels, thus revealing the importance of targeting intramycobacterial redox metabolism for controlling TB infection. (C) 2015 The Authors. Published by Elsevier Inc.

Hemagglutinin sequence conservation guided stem immunogen design from influenza A H3 subtype

Seasonal epidemics caused by influenza A (H1 and H3 subtypes) and B viruses are a major global health threat. The traditional, trivalent influenza vaccines have limited efficacy because of rapid antigenic evolution of the circulating viruses. This antigenic variability mediates viral escape from the host immune responses, necessitating annual vaccine updates. Influenza vaccines elicit a protective antibody response, primarily targeting the viral surface glycoprotein hemagglutinin (HA). However, the predominant humoral response is against the hypervariable head domain of HA, thereby restricting the breadth of protection. In contrast, the conserved, subdominant stem domain of HA is a potential ``universal'' vaccine candidate. We designed an HA stem-fragment immunogen from the 1968 pandemic H3N2 strain (A/Hong Kong/1/68) guided by a comprehensive H3 HA sequence conservation analysis. The biophysical properties of the designed immunogen were further improved by C-terminal fusion of a trimerization motif, ``isoleucine-zipper'', or ``foldon''. These immunogens elicited cross-reactive, antiviral antibodies and conferred partial protection against a lethal, homologous HK68 virus challenge in vivo. Furthermore, bacterial expression of these immunogens is economical and facilitates rapid scale-up.

Haloarchaeal gas vesicle nanoparticles displaying Salmonella antigens as a novel approach to vaccine development

A safe, effective, and inexpensive vaccine against typhoid and other Salmonella diseases is urgently needed. In order to address this need, we are developing a novel vaccine platform employing buoyant, self-adjuvanting gas vesicle nanoparticles (GVNPs) from the halophilic archaeon Halobacterium sp. NRC-1, bioengineered to display highly conserved Salmonella enterica antigens. As the initial antigen for testing, we selected SopB, a secreted inosine phosphate effector protein injected by pathogenic S. enterica bacteria during infection into the host cells. Two highly conserved sopB gene segments near the 3'- region, named sopB4 and sopB5, were each fused to the grIpC gene, and resulting SopB-GVNPs were purified by centrifugally accelerated flotation. Display of SopB4 and SopB5 antigenic epitopes on GVNPs was established by Western blotting analysis using antisera raised against short synthetic peptides of SopB. Immunostimulatory activities of the SopB4 and B5 nanoparticles were tested by intraperitoneal administration of SopB-GVNPs to BALB/c mice which had been immunized with S. enterica serovar Typhimurium 14028 ApmrG-H111-D (DV-STM-07), a live attenuated vaccine strain. Proinflammatory cytokines IFN-y, IL-2, and IL-9 were significantly induced in mice boosted with SopB5-GVNPs, consistent with a robust Thl response. After challenge with virulent S. enterica serovar Typhimurium 14028, bacterial burden was found to be diminished in spleen of mice boosted with SopB4-GVNPs and absent or significantly diminished in liver, mesenteric lymph node, and spleen of mice boosted with SopB5GVNPs, indicating that the C-terminal portions of SopB displayed on GVNPs elicit a protective response to Salmonella infection in mice. SopB antigen-GVNPs were also found to be stable at elevated temperatures for extended periods without refrigeration. The results show that bioengineered GVNPs are likely to represent a valuable platform for antigen delivery and development of improved vaccines against Salmonella and other diseases.

Protection of Digital Telecom Exchanges Against Lightning Surges and Earth Faults

Low-power electronic devices used in digital telecom exchanges are vulnerable to surge voltages and currents primarily originating from natural lightning or due to the direct interactions between electric power and telecommunication lines, etc., causing the earth/ground potential rise, neutral potential rise, and faults in the system. The fault currents may flow directly to telecom lines or through the equipment to the customer's premises, causing adequate damage to the equipment and personnel safety. In wireline applications, analog or digital, central office, exchanges, and subscriber sides have to be protected. Decisive protection and protective methods have to be employed for proper functioning of the equipment under overvoltage/overcurrent conditions. Current investigation reports some interesting results obtained on the recently developed high-voltage high-current protection cards used in digital telecom exchanges. The performances of protection cards both for the ring wave and hybrid wave surges are evaluated and presented. The surge generators required for the investigation are developed and fabricated in house as per the relevant telecom standards.

Mycobacteria-responsive sonic hedgehog signaling mediates programmed death-ligand 1-and prostaglandin E-2-induced regulatory T cell expansion

CD4(+)CD25(+)FoxP3(+) regulatory T cells (Tregs) are exploited by mycobacteria to subvert the protective host immune responses. The Treg expansion in the periphery requires signaling by professional antigen presenting cells and in particularly dendritic cells (DC). However, precise molecular mechanisms by which mycobacteria instruct Treg expansion via DCs are not established. Here we demonstrate that mycobacteria-responsive sonic hedgehog (SHH) signaling in human DCs leads to programmed death ligand-1 (PD-L1) expression and cyclooxygenase (COX)-2-catalyzed prostaglandin E-2 (PGE(2)) that orchestrate mycobacterial infection-induced expansion of Tregs. While SHH-responsive transcription factor GLI1 directly arbitrated COX-2 transcription, specific microRNAs, miR-324-5p and miR-338-5p, which target PD-L1 were downregulated by SHH signaling. Further, counter-regulatory roles of SHH and NOTCH1 signaling during mycobacterial-infection of human DCs was also evident. Together, our results establish that Mycobacterium directs a fine-balance of host signaling pathways and molecular regulators in human DCs to expand Tregs that favour immune evasion of the pathogen.

Experimental Study on Dynamic Properties of High Strength Fiber Clusters

In this paper, the dynamic behaviors of several kinds of high strength fibers, including Kevlar, UHMPE, glass fibers, carbon fibers etc., are investigated experimentally, with a Split Hopkinson Tension Bar (SHTB). The effect of strain rate on the modulus, strength, failure strain and failure characteristics of fibers, under impact loading, is analyzed with the relative stress vs. strain curves. At the same time, the mechanism about the rate dependence of mechanical behaviors of various fibers is discussed based on the understanding on the microstructures and deformation models of materials. Some comments are also presented on the decentralization of experimental results, and a new method called traveling wave method is presented to increase the experimental accuracy. Research results obtained in this paper will benefit to understand the energy absorption and to build up the constitutive law of protective materials reinforced by high strength fibers.