PLGA Nanoparticle-Based Dissolving Microneedle Vaccine of Clostridium perfringens ε Toxin.

Epsilon toxin (ETX) is an exotoxin produced by type B and D Clostridium perfringens that causes enterotoxemia or necrotic enteritis in animals such as goats, sheep, and cattle. Vaccination is a key method in preventing such diseases. In this study, we developed a new type of dissolving microneedle patch (dMN) with a nanoparticle adjuvant for enhanced immune response to deliver the rETXY196E-C protein vaccine. We chose FDA-approved poly(lactic-co-glycolic acid) (PLGA) to prepare nanospheres as the vaccine adjuvant and introduced dimethyldioctadecylammonium bromide (DDAB) to make the surface of PLGA nanoparticles (PLGA NPs) positively charged for antigen adsorption. PLGA NPs with a diameter of 100~200 nm, a surface ZETA potential of approximately +40 mV, and good safety were successfully prepared and could effectively adsorb rETXY196E-C protein. Using non-toxic and antibacterial fish gelatin as the microneedle (MN) matrix, we prepared a PLGA-DDAB dMN vaccine with good mechanical properties that successfully penetrated the skin. After immunization of subcutaneous (SC) and dMN, antibody titers of the PLGA and Al adjuvant groups were similar in both two immune ways. However, in vivo neutralization experiments showed that the dMN vaccines had a better protective effect. When challenged with 100 × LD50 GST-ETX, the survival rate of the MN group was 100%, while that of the SC Al group was 80%. However, a 100% protective effect was achieved in both immunization methods using PLGA NPs. In vitro neutralization experiments showed that the serum antibodies from the dMN and SC PLGA NPs groups both protect naive mice from 10 × LD50 GST-ETX attack after being diluted 20 times and could also protect MDCK cells from 20 × CT50 GST-ETX attack. In conclusion, the PLGA-DDAB dMN vaccine we prepared has good mechanical properties, immunogenicity, and protection, and can effectively prevent ETX poisoning. This provides a better way of delivering protein vaccines.

Microinjection of urotensin II into the rostral ventrolateral medulla increases sympathetic vasomotor tone via the GPR14/ERK pathway in rats.

The present study aimed to reveal the effects of urotensin II (UII) on sympathetic vasomotor tone in the rostral ventrolateral medulla (RVLM). UII (0.3, 3, and 30 nmol/L, 50 nL) was microinjected into the RVLM. Blood pressure (BP), heart rate (HR), and renal sympathetic nerve activity (RSNA) were measured to determine the sympathetic vasomotor tone. BP, HR, and RSNA were simultaneously recorded after drugs had been microinjected into the RVLM. Microinjection of UII (0.3, 3, and 30 nmol/L, 50 nL) into the RVLM significantly increased BP, HR, and RSNA. Pretreatment with BIM23127 (300 nmol/L, 50 nL), a potent antagonist of the UII receptor GPR14, abolished the effect of UII. Previous microinjection of PD98059 (25 µmol/L, 50 nL), an inhibitor of ERK, significantly suppressed the effects of UII. Preinjection of an inhibitor of the N-type Ca2+ channel, ω-conotoxin GVIA (50 nmol/L, 50 nL), inhibited the effects of UII. The present study demonstrated that microinjection of UII into the RVLM significantly increased sympathetic vasomotor tone, which was mediated by the GPR14/ERK/N-type Ca2+ channel pathway. UII may become a novel therapeutic target for autonomic nervous system regulation, especially in hypertension.

Universal patterns in passenger flight departure delays.

Departure delays are a major cause of economic loss and inefficiency in the growing industry of passenger flights. A departure delay of a current flight is inevitably affected by the late arrival of the flight immediately preceding it with the same aircraft. We seek to understand the mechanisms of such propagated delays, and to obtain universal metrics by which to evaluate an airline's operational effectiveness in delay alleviation. Here we use big data collected by the American Bureau of Transportation Statistics to design models of flight delays. Offering two dynamic models of delay propagation, we divided all carriers into two groups exhibiting a shifted power law or an exponentially truncated shifted power law delay distribution, revealing two universal delay propagation classes. Three model parameters, extracted directly from dual data mining, help characterize each airline's operational efficiency in delay mitigation. Therefore, our modeling framework provides the crucially lacking evaluation indicators for airlines, potentially contributing to the mitigation of future departure delays.

Iodosylbenzene-Pseudohalide-Based Initiators for Radical Polymerization.

Iodosylbenzene reacts with various (pseudo)halides (trimethylsilyl azide or isocyanate or potassium azide, cyanate, and bromide) to yield unstable hypervalent iodine(III) compounds, PhIX2 (X = (pseudo)halide), that undergo rapid homolysis of the hypervalent I-X bonds and generate (pseudo)halide radicals, which can initiate the polymerization of styrene, (meth)acrylates, and vinyl esters. Polymers are formed containing (pseudo)halide functionalities at the α-chain end but, depending on the termination mechanism and the occurrence of transfer of (pseudo)halide groups from the initiator to the propagating radicals, also at the ω-chain end. With slowly polymerizing monomers (styrene and methyl methacrylate) and initiators that were generated rapidly at high concentrations and were especially unstable, the reactions proceeded via a "dead-end" polymerization mechanism, and only low to moderate monomer conversions were attained. When the initiator was generated more slowly and continuously throughout the polymerization (using the combination of iodosylbenzene with the poorly soluble potassium (pseudo)halide salts), typically higher conversions and higher molecular weights were reached. The presence of (pseudo)halide functionalities in the polymers was proved by elemental analysis, IR, and NMR spectroscopy. The azide-containing polymers underwent click-type coupling reactions with dialkynes, while the (iso)cyanate-containing polymers reacted with diamines to afford high-molecular-weight polymers with triazole- and urea-type interchain links, respectively.

Synthesis and biological evaluation of novel curcuminoid derivatives.

Curcuminoids have been reported to possess multiple bioactivities, such as antioxidant, anticancer and anti-inflammatory properties. Three novel series of curcuminoid derivatives (11a-h, 15a-h and 19a-d) with enhanced bioactivity have been synthesized. Among the synthesized compounds, 11b exhibited the most significant activity with an MIC of 0.5 µM /mL against selected medically important Gram-positive cocci (S. aureus and S. viridans) and Gram-negative bacilli (E. coli and E. cloacae). The derivatives exhibited remarkable results in an antioxidant test with an IC50 2.4- to 9.3-folder smaller than curcuminoids. With respect to antiproliferative activity against Hep-G2, LX-2, SMMC7221 and MDA-MB-231, the derivatives exhibited an effect stronger than curcuminoids with an IC50 ranging from 0.18 to 4.25 µM.

Enhanced electrical conductivity in polystyrene nanocomposites at ultra-low graphene content.

We compared the electrical conductivity of multiwalled-carbon-nanotube/polystyrene and graphene/polystyrene composites. The conductivity of polystyrene increases from ∼6.7 × 10(-14) to ∼3.49 S/m, with an increase in graphene content from ∼0.11 to ∼1.1 vol %. This is ∼2-4 orders of magnitude higher than for multiwalled-carbon-nanotube/polystyrene composites. Furthermore, we show that the conductivity of the graphene/polystyrene system can be significantly enhanced by incorporation of polylactic acid. The volume-exclusion principle forces graphene into the polystyrene-rich regions (selective localization) and generates ∼4.5-fold decrease in its percolation threshold from ∼0.33 to ∼0.075 vol %.

Microinjection of resveratrol into rostral ventrolateral medulla decreases sympathetic vasomotor tone through nitric oxide and intracellular Ca2+ in anesthetized male rats.

AIM: To define the effect of resveratrol (RES) on the central regulation of blood pressure (BP), heart rate (HR), and renal sympathetic nerve activity (RSNA). METHODS: RES was microinjected into the rostral ventrolateral medulla (RVLM), and BP, HR, and RSNA were recorded simultaneously in anesthetized rats. RESULTS: A microinjection of RES (20, 40, and 80 micromol/L, 0.2 microL) into the RVLM dose dependently decreased BP, HR, and RSNA. Pretreatment with an anti-estrogen tamoxifen (100 micromol/L, 0.2 microL) did not affect the effects of RES. Pretreatment with NG-nitro- L-arginine methyl ester (100 micromol/L, 0.2 microL), an inhibitor of nitric oxide (NO) synthase, could completely abolish the effect of RES. A prior microinjection of Bay K8644 (500 nmol/L, 0.2 microL), an agonist of calcium channels, could also abrogate the effect of RES. Prior administration of a potent inhibitor of tyrosine phosphatase, sodium orthovanadate (1 mmol/L, 0.2 microL), could partially attenuate the inhibitory effect of RES. CONCLUSION: The results suggest that a microinjection of RES into the RVLM inhibits BP, HR, and RSNA. The effects may be mediated by NO synthesis and a decrease in Ca2+ influx, in which protein tyrosine kinase is involved.