Synthesis, morphological structures and material characterization of electrospun PLA: PCL/magnetic nanoparticle composites for drug delivery

The effects of pure and impure magnetic nanoparticles (MPs) with three different concentrations (0.01, 0.1 and 1 wt%/v) on the morphological structure, crystallinity level, thermal properties and constituent interactions of electrospun poly(lactic acid) (PLA): poly(e-caprolactone) (PCL) based composites were investigated by means of scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray diffraction (XRD), differential scanning calorimetry (DSC), gel permeation chromatography (GPC), Fourier transform infrared spectroscopy (FTIR) and drug release tests using UV–vis spectrophotometry. Tetracycline hydrochloride (TCH), as a typical therapeutic compound, was loaded into these composite fibrous structures to study their application for drug delivery. The infrared spectra of composite nanofibers confirm the successful embedding of MPs into the fibrous networks. The addition of pure MPs increased the solution viscosity and thus promoted the MP dispersion inside the electrospun composite fiber mats. Impure MPs led to considerably lower average fiber diameters, and could generate unique cell structures that were reported for the first time in this study. The accelerated release of TCH was found by adding pure MPs to PLA: PCL blends. This characteristic was reflected in the parameters of Ritger-Peppas and Zeng models, which were well fitted to our experimental drug release data

Penicillium menonorum, a new species related to P. pimiteouiense

Penicillium menonorum is described as a new monoverticillate, non-vesiculate species that resembles P. restrictum and P. pimiteouiense. On the basis of phylogenetic analysis of DNA sequences from four loci, P. menonorum occurs in a clade with P. pimiteouiense, P. vinaceum, P. guttulosum, P. rubidurum, and P. parvum. Genealogical concordance analysis was applied to P. pimiteouiense and P. parvum, substantiating the phenotypically defined species. The species P. rubidurum, P. guttulosum, and P. menonorum were on distinct branches statistically excluded from inclusion in other species and have distinct phenotypes

Protocol-Inspired Hardware Testing

The relevance of protocol conformance testing techniques to hardware testing is discussed. It is shown that the ioconf (input-output conformance) approach used in protocol testing can be applied to generate tests for a synchronous hardware design using its formal specification. The generated tests are automatically applied to a circuit by a VHDL testbench, thus giving confidence that the hardware design meets its high-level formal specification. Case studies illustrate how the ideas can be applied to standard hardware verification benchmarks such as the Single Pulser and Black-Jack Dealer

Determining the neurotransmitter concentration profile at active synapses

Establishing the temporal and concentration profiles of neurotransmitters during synaptic release is an essential step towards understanding the basic properties of inter-neuronal communication in the central nervous system. A variety of ingenious attempts has been made to gain insights into this process, but the general inaccessibility of central synapses, intrinsic limitations of the techniques used, and natural variety of different synaptic environments have hindered a comprehensive description of this fundamental phenomenon. Here, we describe a number of experimental and theoretical findings that has been instrumental for advancing our knowledge of various features of neurotransmitter release, as well as newly developed tools that could overcome some limits of traditional pharmacological approaches and bring new impetus to the description of the complex mechanisms of synaptic transmission

The time-profile of cell growth in fission yeast: model selection criteria favoring bilinear models over exponential ones

BACKGROUND: There is considerable controversy concerning the exact growth profile of size parameters during the cell cycle. Linear, exponential and bilinear models are commonly considered, and the same model may not apply for all species. Selection of the most adequate model to describe a given data-set requires the use of quantitative model selection criteria, such as the partial (sequential) F-test, the Akaike information criterion and the Schwarz Bayesian information criterion, which are suitable for comparing differently parameterized models in terms of the quality and robustness of the fit but have not yet been used in cell growth-profile studies. RESULTS: Length increase data from representative individual fission yeast (Schizosaccharomyces pombe) cells measured on time-lapse films have been reanalyzed using these model selection criteria. To fit the data, an extended version of a recently introduced linearized biexponential (LinBiExp) model was developed, which makes possible a smooth, continuously differentiable transition between two linear segments and, hence, allows fully parametrized bilinear fittings. Despite relatively small differences, essentially all the quantitative selection criteria considered here indicated that the bilinear model was somewhat more adequate than the exponential model for fitting these fission yeast data. CONCLUSION: A general quantitative framework was introduced to judge the adequacy of bilinear versus exponential models in the description of growth time-profiles. For single cell growth, because of the relatively limited data-range, the statistical evidence is not strong enough to favor one model clearly over the other and to settle the bilinear versus exponential dispute. Nevertheless, for the present individual cell growth data for fission yeast, the bilinear model seems more adequate according to all metrics, especially in the case of wee1Δ cells

Is there a common water-activity limit for the three domains of life?

Archaea and Bacteria constitute a majority of life systems on Earth but have long been considered inferior to Eukarya in terms of solute tolerance. Whereas the most halophilic prokaryotes are known for an ability to multiply at saturated NaCl (water activity (a w) 0.755) some xerophilic fungi can germinate, usually at high-sugar concentrations, at values as low as 0.650-0.605 a w. Here, we present evidence that halophilic prokayotes can grow down to water activities of <0.755 for Halanaerobium lacusrosei (0.748), Halobacterium strain 004.1 (0.728), Halobacterium sp. NRC-1 and Halococcus morrhuae (0.717), Haloquadratum walsbyi (0.709), Halococcus salifodinae (0.693), Halobacterium noricense (0.687), Natrinema pallidum (0.681) and haloarchaeal strains GN-2 and GN-5 (0.635 a w). Furthermore, extrapolation of growth curves (prone to giving conservative estimates) indicated theoretical minima down to 0.611 a w for extreme, obligately halophilic Archaea and Bacteria. These were compared with minima for the most solute-tolerant Bacteria in high-sugar (or other non-saline) media (Mycobacterium spp., Tetragenococcus halophilus, Saccharibacter floricola, Staphylococcus aureus and so on) and eukaryotic microbes in saline (Wallemia spp., Basipetospora halophila, Dunaliella spp. and so on) and high-sugar substrates (for example, Xeromyces bisporus, Zygosaccharomyces rouxii, Aspergillus and Eurotium spp.). We also manipulated the balance of chaotropic and kosmotropic stressors for the extreme, xerophilic fungi Aspergillus penicilloides and X. bisporus and, via this approach, their established water-activity limits for mycelial growth (∼0.65) were reduced to 0.640. Furthermore, extrapolations indicated theoretical limits of 0.632 and 0.636 a w for A. penicilloides and X. bisporus, respectively. Collectively, these findings suggest that there is a common water-activity limit that is determined by physicochemical constraints for the three domains of life

Intraspecific Aflatoxin Inhibition in Aspergillus flavus Is Thigmoregulated, Independent of Vegetative Compatibility Group and Is Strain Dependent

Biological control of preharvest aflatoxin contamination by atoxigenic stains of Aspergillus flavus has been demonstrated in several crops. The assumption is that some form of competition suppresses the fungus's ability to infect or produce aflatoxin when challenged. Intraspecific aflatoxin inhibition was demonstrated by others. This work investigates the mechanistic basis of that phenomenon. A toxigenic and atoxigenic isolate of A. flavus which exhibited intraspecific aflatoxin inhibition when grown together in suspended disc culture were not inhibited when grown in a filter insert-plate well system separated by a .4 or 3 µm membrane. Toxigenic and atoxigenic conidial mixtures (50∶50) placed on both sides of these filters restored inhibition. There was ∼50% inhibition when a 12 µm pore size filter was used. Conidial and mycelial diameters were in the 3.5–7.0 µm range and could pass through the 12 µm filter. Larger pore sizes in the initially separated system restored aflatoxin inhibition. This suggests isolates must come into physical contact with one another. This negates a role for nutrient competition or for soluble diffusible signals or antibiotics in aflatoxin inhibition. The toxigenic isolate was maximally sensitive to inhibition during the first 24 hrs of growth while the atoxigenic isolate was always inhibition competent. The atoxigenic isolate when grown with a green fluorescent protein (GFP) toxigenic isolate failed to inhibit aflatoxin indicating that there is specificity in the touch inhibiton. Several atoxigenic isolates were found which inhibited the GFP isolate. These results suggest that an unknown signaling pathway is initiated in the toxigenic isolate by physical interaction with an appropriate atoxigenic isolate in the first 24 hrs which prevents or down-regulates normal expression of aflatoxin after 3–5 days growth. We suspect thigmo-downregulation of aflatoxin synthesis is the mechanistic basis of intraspecific aflatoxin inhibition and the major contributor to biological control of aflatoxin contamination

Flavor Decomposition of the Polarized Quark Distributions in the Nucleon from Inclusive and Semi-inclusive Deep-inelastic Scattering

Spin asymmetries of semi-inclusive cross sections for the production of positively and negatively charged hadrons have been measured in deep-inelastic scattering of polarized positrons on polarized hydrogen and 3He targets, in the kinematic range 0.023<x<0.6 and 1 GeV^2<Q^2<10 GeV^2. Polarized quark distributions are extracted as a function of x for up $(u+u_bar) and down (d+d_bar) flavors. The up quark polarization is positive and the down quark polarization is negative in the measured range. The polarization of the sea is compatible with zero. The first moments of the polarized quark distributions are presented. The isospin non-singlet combination Delta_q_3 is consistent with the prediction based on the Bjorken sum rule. The moments of the polarized quark distributions are compared to predictions based on SU(3)_f flavor symmetry and to a prediction from lattice QCD.Comment: 14 pages, 6 figures (eps format), 10 tables in Latex New version contains tables of asymmetries and correlation matri

New taxa of Neosartorya and Aspergillus in Aspergillus section Fumigati

Three new species of Neosartorya and one new Aspergillus of section Fumigati are proposed using a polyphasic approach based on morphology, extrolite production and partial β-tubulin, calmodulin, and actin gene sequences. The phylogenetic analyses using the three genes clearly show that the taxa grouped separately from the known species and confirmed the phenotypic differences. Neosartorya denticulata is characterized by its unique denticulate ascospores with a prominent equatorial furrow; N. assulata by well developed flaps on the convex surface of the ascospores which in addition have two distinct equatorial crests and N. galapagensis by a funiculose colony morphology, short and narrow conidiophores and ascospores with two wide equatorial crests with a microtuberculate convex surface. Aspergillus turcosus can be distinguished by velvety, gray turquoise colonies and short, loosely columnar conidial heads. The four new taxa also have unique extrolite profiles, which contain the mycotoxins gliotoxin and viriditoxin in N. denticulate; apolar compounds provisionally named NEPS in N. assulata and gregatins in N. galapagensis. A. turcosus produced kotanins. N.denticulata sp. nov., N. assulata sp. nov., N. galapagensis sp. nov., and A. turcosus sp. nov. are described and illustrated

Protein profiling of the dimorphic, pathogenic fungus, Penicillium marneffei

<p>Abstract</p> <p>Background</p> <p><it>Penicillium marneffei </it>is a pathogenic fungus that afflicts immunocompromised individuals having lived or traveled in Southeast Asia. This species is unique in that it is the only dimorphic member of the genus. Dimorphism results from a process, termed phase transition, which is regulated by temperature of incubation. At room temperature, the fungus grows filamentously (mould phase), but at body temperature (37°C), a uninucleate yeast form develops that reproduces by fission. Formation of the yeast phase appears to be a requisite for pathogenicity. To date, no genes have been identified in <it>P. marneffei </it>that strictly induce mould-to-yeast phase conversion. In an effort to help identify potential gene products associated with morphogenesis, protein profiles were generated from the yeast and mould phases of <it>P. marneffei</it>.</p> <p>Results</p> <p>Whole cell proteins from the early stages of mould and yeast development in <it>P. marneffei </it>were resolved by two-dimensional gel electrophoresis. Selected proteins were recovered and sequenced by capillary-liquid chromatography-nanospray tandem mass spectrometry. Putative identifications were derived by searching available databases for homologous fungal sequences. Proteins found common to both mould and yeast phases included the signal transduction proteins cyclophilin and a RACK1-like ortholog, as well as those related to general metabolism, energy production, and protection from oxygen radicals. Many of the mould-specific proteins identified possessed similar functions. By comparison, proteins exhibiting increased expression during development of the parasitic yeast phase comprised those involved in heat-shock responses, general metabolism, and cell-wall biosynthesis, as well as a small GTPase that regulates nuclear membrane transport and mitotic processes in fungi. The cognate gene encoding the latter protein, designated <it>RanA</it>, was subsequently cloned and characterized. The <it>P. marneffei </it>RanA protein sequence, which contained the signature motif of Ran-GTPases, exhibited 90% homology to homologous <it>Aspergillus </it>proteins.</p> <p>Conclusion</p> <p>This study clearly demonstrates the utility of proteomic approaches to studying dimorphism in <it>P. marneffei</it>. Moreover, this strategy complements and extends current genetic methodologies directed towards understanding the molecular mechanisms of phase transition. Finally, the documented increased levels of RanA expression suggest that cellular development in this fungus involves additional signaling mechanisms than have been previously described in <it>P. marneffei</it>.</p