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Sample records for alternative host matrix

  1. Insects as alternative hosts for phytopathogenic bacteria.

    PubMed

    Nadarasah, Geetanchaly; Stavrinides, John

    2011-05-01

    Phytopathogens have evolved specialized pathogenicity determinants that enable them to colonize their specific plant hosts and cause disease, but their intimate associations with plants also predispose them to frequent encounters with herbivorous insects, providing these phytopathogens with ample opportunity to colonize and eventually evolve alternative associations with insects. Decades of research have revealed that these associations have resulted in the formation of bacterial-vector relationships, in which the insect mediates dissemination of the plant pathogen. Emerging research, however, has highlighted the ability of plant pathogenic bacteria to use insects as alternative hosts, exploiting them as they would their primary plant host. The identification of specific bacterial genetic determinants that mediate the interaction between bacterium and insect suggests that these interactions are not incidental, but have likely arisen following the repeated association of microorganisms with particular insects over evolutionary time. This review will address the biology and ecology of phytopathogenic bacteria that interact with insects, including the traditional role of insects as vectors, as well as the newly emerging paradigm of insects serving as alternative primary hosts. Also discussed is one case where an insect serves as both host and vector, which may represent a transitionary stage in the evolution of insect-phytopathogen associations. PMID:21251027

  2. Synthesis of Ge nanocrystals embedded in a Si host matrix

    NASA Astrophysics Data System (ADS)

    Ngiam, Shih-Tung; Jensen, Klavs F.; Kolenbrander, K. D.

    1994-12-01

    The synthesis of a composite material consisting of Ge nanoclusters (greater than or equal to 2 nm in diameter) embedded in a Si host matrix is reported. The Ge nanoparticles are produced by pulsed laser ablation and are codeposited in a Si film simultaneously grown by chemical beam epitaxy using disilane. Scanning transmission electron microscopy, combined with energy-dispersive x-ray measurements, show that discrete Ge particles (greater than or equal to 2 nm diameter) are deposited within a polycrystalline Si host matrix. High-resolution transmission electron microscopy reveals that the paricles are crystalline with a lattice spacing corresponding to that of Ge. The enhancement of Si deposition rates from silanes in the presence of Ge, previously demonstrated in chemical vapor deposition of Si(1 - x)Ge(x) alloys, is shown to facilitate the growth of a Si layer around the Ge nanocrystals. The overall composition of the Ge cluster/Si host composite material is determined by Rutherford backscattering measurements.

  3. Dentin matrix degradation by host matrix metalloproteinases: inhibition and clinical perspectives toward regeneration

    PubMed Central

    Chaussain, Catherine; Boukpessi, Tchilalo; Khaddam, Mayssam; Tjaderhane, Leo; George, Anne; Menashi, Suzanne

    2013-01-01

    Bacterial enzymes have long been considered solely accountable for the degradation of the dentin matrix during the carious process. However, the emerging literature suggests that host-derived enzymes, and in particular the matrix metalloproteinases (MMPs) contained in dentin and saliva can play a major role in this process by their ability to degrade the dentin matrix from within. These findings are important since they open new therapeutic options for caries prevention and treatment. The possibility of using MMP inhibitors to interfere with dentin caries progression is discussed. Furthermore, the potential release of bioactive peptides by the enzymatic cleavage of dentin matrix proteins by MMPs during the carious process is discussed. These peptides, once identified, may constitute promising therapeutical tools for tooth and bone regeneration. PMID:24198787

  4. ISOLATION AND PHYLOGENETIC ANALYSIS OF XYLELLA FASTIDIOSA FROM ITS INVASIVE ALTERNATIVE HOST, PORCELAIN BERRY

    Technology Transfer Automated Retrieval System (TEKTRAN)

    A strain of X. fastidiosa was isolated from an invasive alternative host species, porcelain berry. Its genetic relationship with strains isolated from a native alternative host, wild grape, and other economically important hosts including grape, peach, plum, oak, mulberry, maple and oleander was det...

  5. Measles Virus Matrix Protein Inhibits Host Cell Transcription

    PubMed Central

    Yu, Xuelian; Shahriari, Shadi; Li, Hong-Mei; Ghildyal, Reena

    2016-01-01

    Measles virus (MeV) is a highly contagious virus that still causes annual epidemics in developing countries despite the availability of a safe and effective vaccine. Additionally, importation from endemic countries causes frequent outbreaks in countries where it has been eliminated. The M protein of MeV plays a key role in virus assembly and cytopathogenesis; interestingly, M is localised in nucleus, cytoplasm and membranes of infected cells. We have used transient expression of M in transfected cells and in-cell transcription assays to show that only some MeV M localizes to the nucleus, in addition to cell membranes and the cytoplasm as previously described, and can inhibit cellular transcription via binding to nuclear factors. Additionally, MeV M was able to inhibit in vitro transcription in a dose-dependent manner. Importantly, a proportion of M is also localized to nucleus of MeV infected cells at early times in infection, correlating with inhibition of cellular transcription. Our data show, for the first time, that MeV M may play a role early in infection by inhibiting host cell transcription. PMID:27551716

  6. Measles Virus Matrix Protein Inhibits Host Cell Transcription.

    PubMed

    Yu, Xuelian; Shahriari, Shadi; Li, Hong-Mei; Ghildyal, Reena

    2016-01-01

    Measles virus (MeV) is a highly contagious virus that still causes annual epidemics in developing countries despite the availability of a safe and effective vaccine. Additionally, importation from endemic countries causes frequent outbreaks in countries where it has been eliminated. The M protein of MeV plays a key role in virus assembly and cytopathogenesis; interestingly, M is localised in nucleus, cytoplasm and membranes of infected cells. We have used transient expression of M in transfected cells and in-cell transcription assays to show that only some MeV M localizes to the nucleus, in addition to cell membranes and the cytoplasm as previously described, and can inhibit cellular transcription via binding to nuclear factors. Additionally, MeV M was able to inhibit in vitro transcription in a dose-dependent manner. Importantly, a proportion of M is also localized to nucleus of MeV infected cells at early times in infection, correlating with inhibition of cellular transcription. Our data show, for the first time, that MeV M may play a role early in infection by inhibiting host cell transcription. PMID:27551716

  7. The Role of Host-derived Dentinal Matrix Metalloproteinases in Reducing Dentin Bonding of Resin Adhesives

    PubMed Central

    Zhang, Shan-chuan; Kern, Matthias

    2009-01-01

    Dentin matrix metalloproteinases (MMPs) are a family of host-derived proteolytic enzymes trapped within mineralized dentin matrix, which have the ability to hydrolyze the organic matrix of demineralized dentin. After bonding with resins to dentin there are usually some exposed collagen fibrils at the bottom of the hybrid layer owing to imperfect resin impregnation of the demineralized dentin matrix. Exposed collagen fibrils might be affected by MMPs inducing hydrolytic degradation, which might result in reduced bond strength. Most MMPs are synthesized and released from odontoblasts in the form of proenzymes, requiring activation to degrade extracellular matrix components. Unfortunately, they can be activated by modern self-etch and etch-and-rinse adhesives. The aim of this review is to summarize the current knowledge of the role of dentinal host-derived MMPs in dentin matrix degradation. We also discuss various available MMP inhibitors, especially chlorhexidine, and suggest that they could provide a potential pathway for inhibiting collagen degradation in bonding interfaces thereby increasing dentin bonding durability. PMID:20690420

  8. Role of Alternate Hosts in Epidemiology and Pathogen Variation of Cereal Rusts.

    PubMed

    Zhao, Jie; Wang, Meinan; Chen, Xianming; Kang, Zhensheng

    2016-08-01

    Cereal rusts, caused by obligate and biotrophic fungi in the genus Puccinia, are important diseases that threaten world food security. With the recent discovery of alternate hosts for the stripe rust fungus (Puccinia striiformis), all cereal rust fungi are now known to be heteroecious, requiring two distinct plant species serving as primary or alternate hosts to complete their sexual life cycle. The roles of the alternate hosts in disease epidemiology and pathogen variation vary greatly from species to species and from region to region because of different climatic and cropping conditions. We focus this review on rust fungi of small grains, mainly stripe rust, stem rust, leaf rust, and crown rust of wheat, barley, oat, rye, and triticale, with emphases on the contributions of alternate hosts to the development and management of rust diseases. PMID:27296143

  9. Evaluation of alternative host bacteria as vehicles for oral administration of bacteriophages

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Survival of bacteriophages through the upper gastrointestinal tract (UGIT) and persistence in the lower gastrointestinal tract (LGIT) is essential for treatment of enteric bacterial infections. We have hypothesized that non-pathogenic Alternative Host Bacteriophage (AHB), originally isolated from p...

  10. Alternative mechanisms of increased eggshell hardness of avian brood parasites relative to host species

    PubMed Central

    Igic, Branislav; Braganza, Kim; Hyland, Margaret M.; Silyn-Roberts, Heather; Cassey, Phillip; Grim, Tomas; Rutila, Jarkko; Moskát, Csaba; Hauber, Mark E.

    2011-01-01

    Obligate brood parasitic birds lay their eggs in nests of other species and parasite eggs typically have evolved greater structural strength relative to host eggs. Increased mechanical strength of the parasite eggshell is an adaptation that can interfere with puncture ejection behaviours of discriminating hosts. We investigated whether hardness of eggshells is related to differences between physical and chemical traits from three different races of the parasitic common cuckoo Cuculus canorus, and their respective hosts. Using tools developed for materials science, we discovered a novel correlate of increased strength of parasite eggs: the common cuckoo's egg exhibits a greater microhardness, especially in the inner region of the shell matrix, relative to its host and sympatric non-host species. We then tested predictions of four potential mechanisms of shell strength: (i) increased relative thickness overall, (ii) greater proportion of the structurally harder shell layers, (iii) higher concentration of inorganic components in the shell matrix, and (iv) elevated deposition of a high density compound, MgCO3, in the shell matrix. We confirmed support only for hypothesis (i). Eggshell characteristics did not differ between parasite eggs sampled from different host nests in distant geographical sites, suggesting an evolutionarily shared microstructural mechanism of stronger parasite eggshells across diverse host-races of brood parasitic cuckoos. PMID:21561966

  11. Alternative mechanisms of increased eggshell hardness of avian brood parasites relative to host species.

    PubMed

    Igic, Branislav; Braganza, Kim; Hyland, Margaret M; Silyn-Roberts, Heather; Cassey, Phillip; Grim, Tomas; Rutila, Jarkko; Moskát, Csaba; Hauber, Mark E

    2011-11-01

    Obligate brood parasitic birds lay their eggs in nests of other species and parasite eggs typically have evolved greater structural strength relative to host eggs. Increased mechanical strength of the parasite eggshell is an adaptation that can interfere with puncture ejection behaviours of discriminating hosts. We investigated whether hardness of eggshells is related to differences between physical and chemical traits from three different races of the parasitic common cuckoo Cuculus canorus, and their respective hosts. Using tools developed for materials science, we discovered a novel correlate of increased strength of parasite eggs: the common cuckoo's egg exhibits a greater microhardness, especially in the inner region of the shell matrix, relative to its host and sympatric non-host species. We then tested predictions of four potential mechanisms of shell strength: (i) increased relative thickness overall, (ii) greater proportion of the structurally harder shell layers, (iii) higher concentration of inorganic components in the shell matrix, and (iv) elevated deposition of a high density compound, MgCO(3), in the shell matrix. We confirmed support only for hypothesis (i). Eggshell characteristics did not differ between parasite eggs sampled from different host nests in distant geographical sites, suggesting an evolutionarily shared microstructural mechanism of stronger parasite eggshells across diverse host-races of brood parasitic cuckoos. PMID:21561966

  12. Thermophysical processes initiated by inert-matrix-hosted nanoparticles heated by laser pulses of different durations

    NASA Astrophysics Data System (ADS)

    Kalenskii, A. V.; Zvekov, A. A.; Nikitin, A. P.; Aduev, B. P.

    2016-03-01

    In the present study, a model for the heating of inert-matrix-hosted metal nanoparticles with laser radiation taking into account the melting processes is examined. The calculations were performed using the characteristics of gold and pentaerythritol tetranitrate materials. The kinetic dependences of the temperature and molten-layer thickness on nanoparticle surface were calculated. The main non-dimensional governing parameters of the model were identified. An expression for the maximum thickness of molten layer was obtained. The results can be used in predicting the stability of nonlinear-optics devices with hosted gold nanoparticles, in raising the efficiency of hyperthermia cancer therapy, and in optimizing the optical detonators.

  13. Tick control: trapping, biocontrol, host management and other alternative strategies

    USGS Publications Warehouse

    Ginsberg, Howard S.

    2014-01-01

    Biology of Ticks is the most comprehensive work on tick biology and tick-borne diseases. This second edition is a multi-authored work, featuring the research and analyses of renowned experts across the globe. Spanning two volumes, the book examines the systematics, biology, structure, ecological adaptations, evolution, genomics and the molecular processes that underpin the growth, development and survival of these important disease-transmitting parasites. Also discussed is the remarkable array of diseases transmitted (or caused) by ticks, as well as modern methods for their control. This book should serve as a modern reference for students, scientists, physicians, veterinarians and other specialists. Volume I covers the biology of the tick and features chapters on tick systematics, tick life cycles, external and internal anatomy, and others dedicated to specific organ systems, specifically, the tick integument, mouthparts and digestive system, salivary glands, waste removal, salivary glands, respiratory system, circulatory system and hemolymph, fat body, the nervous and sensory systems and reproductive systems. Volume II includes chapters on the ecology of non-nidicolous and nidicolous ticks, genetics and genomics (including the genome of the Lyme disease vector Ixodes scapularis) and immunity, including host immune responses to tick feeding and tick-host interactions, as well as the tick's innate immune system that prevents and/or controls microbial infections. Six chapters cover in depth the many diseases caused by the major tick-borne pathogens, including tick-borne protozoa, viruses, rickettsiae of all types, other types of bacteria (e.g., the Lyme disease agent) and diseases related to tick paralytic agents and toxins. The remaining chapters are devoted to tick control using vaccines, acaricides, repellents, biocontrol, and, finally, techniques for breeding ticks in order to develop tick colonies for scientific study.

  14. Plague outbreaks in prairie dog populations explained by percolation thresholds of alternate host abundance

    PubMed Central

    Salkeld, Daniel J.; Salathé, Marcel; Stapp, Paul; Jones, James Holland

    2010-01-01

    Highly lethal pathogens (e.g., hantaviruses, hendra virus, anthrax, or plague) pose unique public-health problems, because they seem to periodically flare into outbreaks before disappearing into long quiescent phases. A key element to their possible control and eradication is being able to understand where they persist in the latent phase and how to identify the conditions that result in sporadic epidemics or epizootics. In American grasslands, plague, caused by Yersinia pestis, exemplifies this quiescent–outbreak pattern, because it sporadically erupts in epizootics that decimate prairie dog (Cynomys ludovicianus) colonies, yet the causes of outbreaks and mechanisms for interepizootic persistence of this disease are poorly understood. Using field data on prairie community ecology, flea behavior, and plague-transmission biology, we find that plague can persist in prairie-dog colonies for prolonged periods, because host movement is highly spatially constrained. The abundance of an alternate host for disease vectors, the grasshopper mouse (Onychomys leucogaster), drives plague outbreaks by increasing the connectivity of the prairie dog hosts and therefore, permitting percolation of the disease throughout the primary host population. These results offer an alternative perspective on plague's ecology (i.e., disease transmission exacerbated by alternative hosts) and may have ramifications for plague dynamics in Asia and Africa, where a single main host has traditionally been considered to drive Yersinia ecology. Furthermore, abundance thresholds of alternate hosts may be a key phenomenon determining outbreaks of disease in many multihost-disease systems. PMID:20660742

  15. Morphometric Differentiation Among Anastrepha fraterculus (Diptera: Tephritidae) Exploiting Sympatric Alternate Hosts.

    PubMed

    Gómez-Cendra, P V; Paulin, L E; Oroño, L; Ovruski, S M; Vilardi, J C

    2016-04-01

    Anastrepha fraterculus (Wiedemann) is currently considered a complex of cryptic species infesting fruits from Mexico to Argentina and represents an interesting biological model for evolutionary studies. Moreover, detecting and quantifying behavioral, morphological, and genetic differentiation among populations is also relevant to the application of environment-friendly control programs. Here, phenotypic differentiation among individuals coexisting in the wild in a Northern region of Argentina was unveiled and associated with host choice. Six morphometric traits were measured in sympatric flies exploiting three different host species. Phenotypic variation was shown to be host-dependent regardless of geographical or temporal overlap. Flies collected from synchronous alternate hosts (peach and walnut) differed from each other despite the lack of geographical isolation. By contrast, flies emerging from guavas that ripen about two months later than peach and walnut showed no significant differentiation in comparison to flies collected from walnuts, but they differ significantly from flies originating from peaches. This result is consistent with the hypothesis that the same population of flies shifts from walnuts to guavas throughout the year, whereas the population of flies that uses peaches as a host is probably exploiting other alternate hosts when peach availability decreases. Further research is needed to study the underlying mechanism. Results are consistent with previous molecular markers (inter-simple sequence repeat-ISSR) research on flies stemming from the same hosts and the same area, suggesting that differentiation among flies emerging from alternative hosts occurs at both genetic and phenotypic levels. The contribution of host preference in long-term genetic differentiation is discussed. PMID:26787122

  16. Temperature-Mediated Effects of Host Alternation on the Adaptation of Myzus persicae (Hemiptera: Aphididae).

    PubMed

    Li, Dan; Zhao, Huiyan; Gao, Huanhuan; Hu, Zuqing; Hu, Xiangshun

    2015-04-01

    Local adaptation, an important phenomenon in ecological speciation, occurs in Myzus persicae (Sulzer), with the tobacco-adapted line proposed as a subspecies. Recent studies showed that temperature could alter the selection strength and direction in host-herbivore interactions. To understand the formation of host-adapted speciation and the effects of temperature on host adaptation, the parthenogenetic progeny of an M. persicae egg were conditioned on two hosts for >10 generations. Then, their life table parameters were studied after reciprocal transfer under a temperature gradient. The results showed that aphids habituated on tobacco (Nicotiana tabacum L.) and rape (Brassica napus L.) had different optimal temperatures, including different upper thresholds of development and reproduction on original and alternative hosts. After habituation for >10 generations, local adaptation of aphids on the host of origin was formed, which was observed as the better performance of the native aphids compared with the foreign ones. The M. persicae that habituated on rape appeared more generalized to the host plants than the aphids that habituated on tobacco. The adaptation patterns of green peach aphids on two hosts varied differentially according to temperature, which verified the temperature-mediated effects of host selection on herbivores, implying the presence of a demographic basis of aphid seasonal migration. PMID:26313192

  17. Infection Potential of Hairy Nightshade By Phytophthora infestans and Epidemiological Implications of the Alternate Host

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Hairy nightshade (Solanum sarrachoides Sendt) is a common weed in the potato agro-ecosystem that can serve as an alternate host for late blight. The epidemiological significance of hairy nightshade to potato late blight has not been documented. Infection rates of P. infestans on potato and hairy nig...

  18. Role of alternate hosts in epidemiology and pathogen variation of cereal rusts

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Cereal rusts, caused by obligate and biotrophic fungi in the genus Puccinia of basidiomycete are an important group of diseases threatening the world food security. With the recent discovery of alternate hosts for the stripe rust fungus (Puccinia striiformis), all cereal rust fungi are now known ...

  19. Extracellular matrix-associated proteome changes during non-host resistance in citrus-Xanthomonas interactions.

    PubMed

    Swaroopa Rani, Tirupaati; Podile, Appa Rao

    2014-04-01

    Non-host resistance (NHR) is a most durable broad-spectrum resistance employed by the plants to restrict majority of pathogens. Plant extracellular matrix (ECM) is a critical defense barrier. Understanding ECM responses during interaction with non-host pathogen will provide insights into molecular events of NHR. In this study, the ECM-associated proteome was compared during interaction of citrus with pathogen Xanthomonas axonopodis pv. citri (Xac) and non-host pathogen Xanthomonas oryzae pv. oryzae (Xoo) at 8, 16, 24 and 48 h post inoculation. Comprehensive analysis of ECM-associated proteins was performed by extracting wall-bound and soluble ECM components using both destructive and non-destructive procedures. A total of 53 proteins was differentially expressed in citrus-Xanthomonas host and non-host interaction, out of which 44 were identified by mass spectrometry. The differentially expressed proteins were related to (1) defense-response (5 pathogenesis-related proteins, 3 miraculin-like proteins (MIR, MIR1 and MIR2) and 2 proteases); (2) enzymes of reactive oxygen species (ROS) metabolism [Cu/Zn superoxide dismutase (SOD), Fe-SOD, ascorbate peroxidase and 2-cysteine-peroxiredoxin]; (3) signaling (lectin, curculin-like lectin and concanavalin A-like lectin kinase); and (4) cell-wall modification (α-xylosidase, glucan 1, 3 β-glucosidase, xyloglucan endotransglucosylase/hydrolase). The decrease in ascorbate peroxidase and cysteine-peroxiredoxin could be involved in maintenance of ROS levels. Increase in defense, cell-wall remodeling and signaling proteins in citrus-Xoo interaction suggests an active involvement of ECM in execution of NHR. Partially compromised NHR in citrus against Xoo, upon Brefeldin A pre-treatment supported the role of non-classical secretory proteins in this phenomenon. PMID:24117905

  20. The Coffee Berry Borer (Hypothenemus hampei) Invades Hawaii: Preliminary Investigations on Trap Response and Alternate Hosts.

    PubMed

    Messing, Russell H

    2012-01-01

    In August 2010 the coffee berry borer, Hypothenemus hampei, was first reported to have invaded the Kona coffee growing region of Hawaii, posing a severe economic challenge to the fourth largest agricultural commodity in the State. Despite its long and widespread occurrence throughout the tropics as the most serious pest of coffee, there are still discrepancies in the literature regarding several basic aspects of berry borer biology relevant to its control. In Kona coffee plantations, we investigated the beetles' response to several trap and lure formulations, and examined the occurrence of beetles in seeds of alternate host plants occurring adjacent to coffee farms. While traps were shown to capture significant numbers of beetles per day, and the occurrence of beetles in alternate hosts was quite rare, the unique situation of coffee culture in Hawaii will make this pest extremely challenging to manage in the Islands. PMID:26466620

  1. The Coffee Berry Borer (Hypothenemus hampei) Invades Hawaii: Preliminary Investigations on Trap Response and Alternate Hosts

    PubMed Central

    Messing, Russell H.

    2012-01-01

    In August 2010 the coffee berry borer, Hypothenemus hampei, was first reported to have invaded the Kona coffee growing region of Hawaii, posing a severe economic challenge to the fourth largest agricultural commodity in the State. Despite its long and widespread occurrence throughout the tropics as the most serious pest of coffee, there are still discrepancies in the literature regarding several basic aspects of berry borer biology relevant to its control. In Kona coffee plantations, we investigated the beetles’ response to several trap and lure formulations, and examined the occurrence of beetles in seeds of alternate host plants occurring adjacent to coffee farms. While traps were shown to capture significant numbers of beetles per day, and the occurrence of beetles in alternate hosts was quite rare, the unique situation of coffee culture in Hawaii will make this pest extremely challenging to manage in the Islands. PMID:26466620

  2. Modelling the effect of an alternative host population on the spread of citrus Huanglongbing

    NASA Astrophysics Data System (ADS)

    d'A. Vilamiu, Raphael G.; Ternes, Sonia; Laranjeira, Francisco F.; de C. Santos, Tâmara T.

    2013-10-01

    The objective of this work was to model the spread of citrus Huanglongbing (HLB) considering the presence of a population of alternative hosts (Murraya paniculata). We developed a compartmental deterministic mathematical model for representing the dynamics of HLB disease in a citrus orchard, including delays in the latency and incubation phases of the disease in the plants and a delay period on the nymphal stage of Diaphorina citri, the insect vector of HLB in Brazil. The results of numerical simulations indicate that alternative hosts should not play a crucial role on HLB dynamics considering a typical scenario for the Recôncavo Baiano region in Brazil . Also, the current policy of removing symptomatic plants every three months should not be expected to significantly hinder HLB spread.

  3. Improving the Performance of Lithium-Sulfur Batteries by Employing Polyimide Particles as Hosting Matrixes.

    PubMed

    Gu, Pei-Yang; Zhao, Yi; Xie, Jian; Binte Ali, Nursimaa; Nie, Lina; Xu, Zhichuan J; Zhang, Qichun

    2016-03-23

    Sulfur cathodes with four polyimide (PI) compounds as hosting matrixes have been prepared through a simple one-step approach. These four PIs-S composites exhibited higher sulfur utilization and better cycling stability than pure sulfur. At a current rate of 300 mA g(-1), the initial discharge capacities of PI-1S, PI-2S, PI-3S, and BBLS reached 1120, 1100, 1150, and 1040 mAh g(-1), respectively. After the 30th cycle, PI-1S, PI-2S, PI-3S, BBLS and pristine sulfur powder still remained discharge capacities of 715, 673, 729, 643, and 550 mAh g(-1). Especially, PI-1S and PI-3S cathodes exhibit excellent cycling stability with the discharge capacities of 522 and 574 mAh g(-1) at the 450th cycle, respectively. PMID:26928242

  4. Effect of host glass matrix on structural and optical behavior of glass-ceramic nanocomposite scintillators

    NASA Astrophysics Data System (ADS)

    Brooke Barta, M.; Nadler, Jason H.; Kang, Zhitao; Wagner, Brent K.; Rosson, Robert; Kahn, Bernd

    2013-12-01

    Composite scintillator systems have received increased attention in recent years due to their promise for merging the radioisotope discrimination capabilities of single crystal scintillators with the high throughput scanning capabilities of portal monitors. However, producing the high light yield required for good energy resolution has proven challenging as scintillation photons are often scattered by variations in refractive index and agglomerated scintillator crystals within the composite. This investigation sought to mitigate these common problems by using glass-ceramic nanocomposite materials systems in which nanoscale scintillating crystallites are precipitated in a controlled manner from a transparent glass matrix. Precipitating crystallites in situ precludes nanoparticle agglomeration, and limiting crystallite size to 50 nm or less mitigates the effect of refractive index mismatch between the crystals and host glass. Cerium-doped gadolinium bromide (GdBr3(Ce)) scintillating crystals were incorporated into sodium-aluminosilicate (NAS) and alumino-borosilicate (ABS) host glass matrices, and the resulting glass-ceramic structures and luminescence behavior were characterized. The as-cast glass from the ABS system displayed a highly ordered microstructure that produced the highest luminescence intensity (light yield) of the samples studied. However, heat treating to form the glass-ceramic precipitated rare-earth oxide crystallites rather than rare-earth halides. This degraded light yield relative to the unaged sample.

  5. Vesicular stomatitis virus matrix protein inhibits host cell-directed transcription of target genes in vivo.

    PubMed Central

    Black, B L; Lyles, D S

    1992-01-01

    Infection by vesicular stomatitis virus (VSV) results in a rapid inhibition of host cell transcription and translation. To determine whether the viral matrix (M) protein was involved in this inhibition of host cell gene expression, an M protein expression vector was cotransfected with a target gene vector, encoding the target gene, encoding chloramphenicol acetyltransferase (CAT). Expression of M protein caused a decrease in CAT activity in a gene dosage-dependent manner, and inhibition was apparent by 12 h posttransfection. The inhibitory effect of M protein was quite potent. The level of M protein required for a 10-fold inhibition of CAT activity was less than 1% of the level of M protein produced during the sixth hour of VSV infection. Northern (RNA) analysis of cotransfected cells showed that expression of M protein caused a reduction in the steady-state level of the vector-encoded mRNAs. Expression of both CAT and M mRNAs was reduced in cells cotransfected with a plasmid encoding M protein, indicating that expression of small amounts of M protein from plasmid DNA inhibits further expression of both M and CAT mRNAs. Nuclear runoff transcription analysis demonstrated that expression of M protein inhibited transcription of the target genes. This is the first report of a viral gene product which is capable of inhibiting transcription in vivo in the absence of any other viral component. Images PMID:1318397

  6. Polypropylene Surgical Mesh Coated with Extracellular Matrix Mitigates the Host Foreign Body Response

    PubMed Central

    Wolf, Matthew T.; Carruthers, Christopher A.; Dearth, Christopher L.; Crapo, Peter M.; Huber, Alexander; Burnsed, Olivia A.; Londono, Ricardo; Johnson, Scott A.; Daly, Kerry A.; Stahl, Elizabeth C.; Freund, John M.; Medberry, Christopher J.; Carey, Lisa E.; Nieponice, Alejandro; Amoroso, Nicholas J.; Badylak, Stephen F.

    2013-01-01

    Surgical mesh devices composed of synthetic materials are commonly used for ventral hernia repair. These materials provide robust mechanical strength and are quickly incorporated into host tissue; factors which contribute to reduced hernia recurrence rates. However, such mesh devices cause a foreign body response with the associated complications of fibrosis and patient discomfort. In contrast, surgical mesh devices composed of naturally occurring extracellular matrix (ECM) are associated with constructive tissue remodeling, but lack the mechanical strength of synthetic materials. A method for applying a porcine dermal ECM hydrogel coating to a polypropylene mesh is described herein with the associated effects upon the host tissue response and biaxial mechanical behavior. Uncoated and ECM coated heavy-weight BARD™ Mesh were compared to the light-weight ULTRAPRO™ and BARD™ Soft Mesh devices in a rat partial thickness abdominal defect overlay model. The ECM coated mesh attenuated the pro-inflammatory response compared to all other devices, with a reduced cell accumulation and fewer foreign body giant cells. The ECM coating degraded by 35 days, and was replaced with loose connective tissue compared to the dense collagenous tissue associated with the uncoated polypropylene mesh device. Biaxial mechanical characterization showed that all of the mesh devices were of similar isotropic stiffness. Upon explantation, the light-weight mesh devices were more compliant than the coated or uncoated heavy-weight devices. The present study shows that an ECM coating alters the default host response to a polypropylene mesh, but not the mechanical properties in an acute in vivo abdominal repair model. PMID:23873846

  7. Modeling the impact of alternative hosts on Helicoverpa zea adaptation to bollgard cotton.

    PubMed

    Gustafson, David I; Head, Graham P; Caprio, Michael A

    2006-12-01

    For highly polyphagous cotton, Gossypium hirsutum L., pests such as Helicoverpa zea (Boddie), a substantial portion of the larval population develops on noncotton alternative hosts. These noncotton hosts potentially provide a natural refuge for H. zea, thereby slowing the evolution of resistance to the Bacillus thuringiensis Berliner (Bt)-derived Cry1Ac protein present in Bollgard cotton. Here, we demonstrate how the measured contribution of such alternative hosts can be included in estimating the "effective refuge" present for H. zea and in modeling resistance evolution in this species. A single-gene, two-compartment model was used in which one compartment represented corn, Zea mays L., and cotton that express the Cry1Ac protein or similar proteins, and the other compartment was the effective refuge, made up of a weighted average of non-Bt cotton and noncotton hosts. The effective refuge was estimated for each of six generations of H. zea based upon available data on larval population densities on different hosts and cropping patterns. Model runs were performed for regions centered on three states: Georgia, Mississippi, and North Carolina. Three sets of fitness cost assumptions for the putative resistance gene were used: none, low, and moderate, with either recessive or additive inheritance for resistance and fitness costs. For Georgia and North Carolina, resistance was predicted to take >30 yr to evolve except in the absence of fitness costs. For Mississippi, results were sensitive to fitness costs: >30 yr with moderate costs, 7-14 yr with low costs, and 6-10 yr without such costs. PMID:17195681

  8. Which Morphological Characteristics Are Most Influenced by the Host Matrix in Downy Mildews? A Case Study in Pseudoperonospora cubensis

    PubMed Central

    Runge, Fabian; Ndambi, Beninweck; Thines, Marco

    2012-01-01

    Before the advent of molecular phylogenetics, species concepts in the downy mildews, an economically important group of obligate biotrophic oomycete pathogens, have mostly been based upon host range and morphology. While molecular phylogenetic studies have confirmed a narrow host range for many downy mildew species, others, like Pseudoperonospora cubensis affect even different genera. Although often morphological differences were found for new, phylogenetically distinct species, uncertainty prevails regarding their host ranges, especially regarding related plants that have been reported as downy mildew hosts, but were not included in the phylogenetic studies. In these cases, the basis for deciding if the divergence in some morphological characters can be deemed sufficient for designation as separate species is uncertain, as observed morphological divergence could be due to different host matrices colonised. The broad host range of P. cubensis (ca. 60 host species) renders this pathogen an ideal model organism for the investigation of morphological variations in relation to the host matrix and to evaluate which characteristics are best indicators for conspecificity or distinctiveness. On the basis of twelve morphological characterisitcs and a set of twelve cucurbits from five different Cucurbitaceae tribes, including the two species, Cyclanthera pedata and Thladiantha dubia, hitherto not reported as hosts of P. cubensis, a significant influence of the host matrix on pathogen morphology was found. Given the high intraspecific variation of some characteristics, also their plasticity has to be taken into account. The implications for morphological species determination and the confidence limits of morphological characteristics are discussed. For species delimitations in Pseudoperonospora it is shown that the ratio of the height of the first ramification to the sporangiophore length, ratio of the longer to the shorter ultimate branchlet, and especially the length and

  9. Nitrogen hurdle of host alternation for a polyphagous aphid and the associated changes of endosymbionts

    PubMed Central

    Liu, Yan-Hong; Kang, Zhi-Wei; Guo, Ya; Zhu, Guo-Shuai; Rahman Shah, M. Mostafizur; Song, Yue; Fan, Yong-Liang; Jing, Xiangfeng; Liu, Tong-Xian

    2016-01-01

    Low proportion of essential amino acids (EAAs) is one of the barriers for animals to use phloem as a diet. Endosymbionts with EAAs synthesis functions are considered crucial for ameliorating the lack of EAAs in insects’ diets. In this study, we transferred the insects from a cabbage-reared Myzus persicae population onto 3 new plant species including eggplant, tobacco and spinach. The performance on these plants was evaluated and the dynamics of endosymbionts in relation to this host alternation were recorded. We found that the EAAs ratio in phloem was largely determined by the concentrations of non-essential amino acids and the higher proportion of EAAs seemed to favor the population establishment on new plant species and the growth of primary endosymbionts inside insects, which indicated that nitrogen quality was an important factor for aphids to infest and spread on new plant hosts. PMID:27094934

  10. Nitrogen hurdle of host alternation for a polyphagous aphid and the associated changes of endosymbionts.

    PubMed

    Liu, Yan-Hong; Kang, Zhi-Wei; Guo, Ya; Zhu, Guo-Shuai; Shah, M Mostafizur Rahman; Song, Yue; Fan, Yong-Liang; Jing, Xiangfeng; Liu, Tong-Xian

    2016-01-01

    Low proportion of essential amino acids (EAAs) is one of the barriers for animals to use phloem as a diet. Endosymbionts with EAAs synthesis functions are considered crucial for ameliorating the lack of EAAs in insects' diets. In this study, we transferred the insects from a cabbage-reared Myzus persicae population onto 3 new plant species including eggplant, tobacco and spinach. The performance on these plants was evaluated and the dynamics of endosymbionts in relation to this host alternation were recorded. We found that the EAAs ratio in phloem was largely determined by the concentrations of non-essential amino acids and the higher proportion of EAAs seemed to favor the population establishment on new plant species and the growth of primary endosymbionts inside insects, which indicated that nitrogen quality was an important factor for aphids to infest and spread on new plant hosts. PMID:27094934

  11. Relative fitness of a generalist parasite on two alternative hosts: a cross-infestation experiment to test host specialization of the hen flea Ceratophyllus gallinae (Schrank).

    PubMed

    Appelgren, A; McCoy, K D; Richner, H; Doligez, B

    2016-05-01

    Host range is a key element of a parasite's ecology and evolution and can vary greatly depending on spatial scale. Generalist parasites frequently show local population structure in relation to alternative sympatric hosts (i.e. host races) and may thus be specialists at local scales. Here, we investigated local population specialization of a common avian nest-based parasite, the hen flea Ceratophyllus gallinae (Schrank), exploiting two abundant host species that share the same breeding sites, the great tit Parus major (Linnaeus) and the collared flycatcher Ficedula albicollis (Temminck). We performed a cross-infestation experiment of fleas between the two host species in two distinct study areas during a single breeding season and recorded the reproductive success of both hosts and parasites. In the following year, hosts were monitored again to assess the long-term impact of cross-infestation. Our results partly support the local specialization hypothesis: in great tit nests, tit fleas caused higher damage to their hosts than flycatcher fleas, and in collared flycatcher nests, flycatcher fleas had a faster larval development rates than tit fleas. However, these results were significant in only one of the two studied areas, suggesting that the location and history of the host population can modulate the specialization process. Caution is therefore called for when interpreting single location studies. More generally, our results emphasize the need to explicitly account for host diversity in order to understand the population ecology and evolutionary trajectory of generalist parasites. PMID:26910399

  12. Bap, a Biofilm Matrix Protein of Staphylococcus aureus Prevents Cellular Internalization through Binding to GP96 Host Receptor

    PubMed Central

    Valle, Jaione; Latasa, Cristina; Gil, Carmen; Toledo-Arana, Alejandro; Solano, Cristina; Penadés, José R.; Lasa, Iñigo

    2012-01-01

    The biofilm matrix, composed of exopolysaccharides, proteins, nucleic acids and lipids, plays a well-known role as a defence structure, protecting bacteria from the host immune system and antimicrobial therapy. However, little is known about its responsibility in the interaction of biofilm cells with host tissues. Staphylococcus aureus, a leading cause of biofilm-associated chronic infections, is able to develop a biofilm built on a proteinaceous Bap-mediated matrix. Here, we used the Bap protein as a model to investigate the role that components of the biofilm matrix play in the interaction of S. aureus with host cells. The results show that Bap promotes the adhesion but prevents the entry of S. aureus into epithelial cells. A broad analysis of potential interaction partners for Bap using ligand overlayer immunoblotting, immunoprecipitation with purified Bap and pull down with intact bacteria, identified a direct binding between Bap and Gp96/GRP94/Hsp90 protein. The interaction of Bap with Gp96 provokes a significant reduction in the capacity of S. aureus to invade epithelial cells by interfering with the fibronectin binding protein invasion pathway. Consistent with these results, Bap deficient bacteria displayed an enhanced capacity to invade mammary gland epithelial cells in a lactating mice mastitis model. Our observations begin to elucidate the mechanisms by which components of the biofilm matrix can facilitate the colonization of host tissues and the establishment of persistent infections. PMID:22876182

  13. Remineralization of demineralized bone matrix (DBM) via alternating solution immersion (ASI).

    PubMed

    Soicher, Matthew A; Christiansen, Blaine A; Stover, Susan M; Leach, J Kent; Fyhrie, David P

    2013-10-01

    In order to achieve successful clinical outcomes, biomaterials used for bone grafts must possess a number of traits including biocompatibility and osteoconductivity. These materials must also demonstrate appropriate mechanical stability to withstand handling as well as support potentially significant stresses at the implant site. Synthetic and natural polymer scaffolds used for bone tissue engineering (BTE) often lack necessary mechanical properties. Our goal was to internally mineralize natural collagenous matrix, thereby increasing mechanical properties of the material to useful levels. Published methods for intrafibrillar collagen mineralization were applied to clinically relevant-sized constructs but did not successfully deposit mineral in the interior of the constructs. To address this limitation, we developed a new technique for the remineralization of demineralized bone matrix (DBM) based on alternating solution immersion, or ASI. Mineral was removed from equine bone specimens, leaving behind a demineralized bone matrix (DBM). This matrix provides a framework for the nucleation and growth of a replacement mineral phase. Plain film radiography and microcomputed tomography (microCT) indicated accumulation of mineral within the DBM, and mechanical testing (3 point bending and compression) revealed a significant increase in stiffness between the DBM and the remineralized bone matrix (RBM). We believe this remineralization process will be useful in the preparation of stiff and strong allografts for clinical application. PMID:23759125

  14. Importance of protein quality versus quantity in alternative host plants for a leaf-feeding insect.

    PubMed

    Barbehenn, Raymond V; Niewiadomski, Julie; Kochmanski, Joseph

    2013-09-01

    The nutritional value of alternative host plants for leaf-feeding insects such as caterpillars is commonly measured in terms of protein quantity. However, nutritional value might also depend on the quality of the foliar protein [i.e., the composition of essential amino acids (EAAs)]. A lack of comparative work on the EAA compositions of herbivores and their host plants has hampered the testing of this hypothesis. We tested the "protein quality hypothesis" using the tree-feeding caterpillars of Lymantria dispar (gypsy moth) and two taxonomically unrelated host plants, red oak (Quercus rubra) and sugar maple (Acer saccharum). Because L. dispar has higher fitness on oak than on maple, support for the hypothesis would be found if protein were of higher quality from oak than from maple. The whole-body EAA composition of L. dispar larvae was measured to estimate its optimum dietary protein composition, which was compared with the EAA compositions of oak and maple leaves. Contrary to the protein quality hypothesis, the EAA compositions of oak and maple were not significantly different in the spring. The growth-limiting EAAs in both tree species were histidine and methionine. Similar results were observed in the summer, with the exception that the histidine composition of oak was between 10 and 15 % greater than in maple leaves. The two main factors that affected the nutritional value of protein from the tree species were the quantities of EAAs, which were consistently higher in oak, and the efficiency of EAA utilization, which decreased from 80 % in May to <50 % in August. We conclude that the relative nutritional value of red oak and sugar maple for L. dispar is more strongly affected by protein quantity than quality. Surveys of many wild herbaceous species also suggest that leaf-feeding insects would be unlikely to specialize on plants based on protein quality. PMID:23297046

  15. Host-Mediated Bioactivation of Pyrazinamide: Implications for Efficacy, Resistance, and Therapeutic Alternatives

    PubMed Central

    Via, Laura E.; Savic, Rada; Weiner, Danielle M.; Zimmerman, Matthew D.; Prideaux, Brendan; Irwin, Scott M.; Lyon, Eddie; O’Brien, Paul; Gopal, Pooja; Eum, Seokyong; Lee, Myungsun; Lanoix, Jean-Philippe; Dutta, Noton K.; Shim, TaeSun; Cho, Jeong Su; Kim, Wooshik; Karakousis, Petros C.; Lenaerts, Anne; Nuermberger, Eric; Barry, Clifton E.; Dartois, Véronique

    2015-01-01

    Pyrazinamide has played a critical role in shortening therapy against drug-sensitive, drug-resistant, active, and latent tuberculosis (TB). Despite widespread recognition of its therapeutic importance, the sterilizing properties of this 60-year-old drug remain an enigma given its rather poor activity in vitro. Here we revisit longstanding paradigms and offer pharmacokinetic explanations for the apparent disconnect between in vitro activity and clinical impact. We show substantial host-mediated conversion of prodrug pyrazinamide (PZA) to the active form, pyrazinoic acid (POA), in TB patients and in animal models. We demonstrate favorable penetration of this pool of circulating POA from plasma into lung tissue and granulomas, where the pathogen resides. In standardized growth inhibition experiments, we show that POA exhibits superior in vitro potency compared to PZA, indicating that the vascular supply of host-derived POA may contribute to the in vivo efficacy of PZA, thereby reducing the apparent discrepancy between in vitro and in vivo activity. However, the results also raise the possibility that subinhibitory concentrations of POA generated by the host could fuel the emergence of resistance to both PZA and POA. In contrast to widespread expectations, we demonstrate good oral bioavailability and exposure in preclinical species in pharmacokinetic studies of oral POA. Baseline exposure of oral POA can be further increased by the xanthine oxidase inhibitor and approved gout drug allopurinol. These promising results pave the way for clinical investigations of oral POA as a therapeutic alternative or an add-on to overcome PZA resistance and salvage this essential TB drug. PMID:26086040

  16. Diversity of alternative hosts of maize stemborers in Trans-Nzoia district of Kenya.

    PubMed

    Kanya, James I; Ngi-Song, Adele J; Sétamou, Mamoudou F; Overholt, William; Ochora, John; Osir, Ellie O

    2004-01-01

    Genetically-engineered (GE) crops such as those expressing insecticidal Bacillus thuringiensis (Bt) toxin genes have the potential to greatly reduce the use of broad spectrum insecticides and increase crop productivity. However, development of resistance by the target insect species is an important consideration in the deployment of this strategy. In areas where GE crops are deployed on a large scale, current resistance management strategies rely on a 'refuge strategy', comprising the incorporation of a certain proportion of non-GE plants in the agro-ecosystems, to conserve susceptible individuals of the target pests. In the USA, simulation models indicate that at least 20% of the crop should be non-Bt plants. In Africa, the target lepidopteran stemborers attack a wide range of wild grass species as well as cultivated cereal crops. Wild grasses generally occur in the vicinity of maize and other cereal fields, and may provide a refuge if GE crops are in the farming systems. To assess the quality of these grasses as refuges, it is critical to obtain information about their size and spatial distribution. In this study, we have assessed the abundance and diversity of alternative refuge of stemborers, mainly wild grasses occurring in the proximity of maize fields, in Trans-Nzoia district, one of the most important maize growing areas in Kenya. The proportion of wild host plants relative to maize was found to decline from 100% during the non-cropping season to <8% during the maize-growing season. The Shannon-Weaver diversity index indicated high variation in the diversity of wild hosts of stemborers between agro-ecological zones in the district. The results of this study are discussed in light of the possible role that wild host plant species might play in stemborer resistance management following the introduction of Bt maize. PMID:15901098

  17. Global Profiling of the Cellular Alternative RNA Splicing Landscape during Virus-Host Interactions.

    PubMed

    Boudreault, Simon; Martenon-Brodeur, Camille; Caron, Marie; Garant, Jean-Michel; Tremblay, Marie-Pier; Armero, Victoria E S; Durand, Mathieu; Lapointe, Elvy; Thibault, Philippe; Tremblay-Létourneau, Maude; Perreault, Jean-Pierre; Scott, Michelle S; Lemay, Guy; Bisaillon, Martin

    2016-01-01

    Alternative splicing (AS) is a central mechanism of genetic regulation which modifies the sequence of RNA transcripts in higher eukaryotes. AS has been shown to increase both the variability and diversity of the cellular proteome by changing the composition of resulting proteins through differential choice of exons to be included in mature mRNAs. In the present study, alterations to the global RNA splicing landscape of cellular genes upon viral infection were investigated using mammalian reovirus as a model. Our study provides the first comprehensive portrait of global changes in the RNA splicing signatures that occur in eukaryotic cells following infection with a human virus. We identify 240 modified alternative splicing events upon infection which belong to transcripts frequently involved in the regulation of gene expression and RNA metabolism. Using mass spectrometry, we also confirm modifications to transcript-specific peptides resulting from AS in virus-infected cells. These findings provide additional insights into the complexity of virus-host interactions as these splice variants expand proteome diversity and function during viral infection. PMID:27598998

  18. Remnant fragments within an agricultural matrix enhance conditions for a rodent host and its fleas.

    PubMed

    Van Der Mescht, Luther; Le Roux, Peter C; Matthee, Sonja

    2013-03-01

    Habitat fragmentation can adversely impact biodiversity, although where remnant fragments of natural vegetation provide favourable conditions the negative effects of fragmentation may be mitigated. Host-parasite systems in fragmented areas have only recently been examined, with parasites generally showing higher prevalence and richness in fragments, mediated by changes in host density. However, the effect of fragmentation on parasite body size and fecundity remains poorly investigated. Thus, here we compared the body size and condition of a generalist rodent host, Rhabdomys pumilio and the body size of 2 common flea species between pristine natural areas and remnant fragments within agriculture areas. Host body length, weight and body condition values were significantly larger in fragments than in pristine natural vegetation. Listropsylla agrippinae fleas showed the same pattern, being significantly larger in fragments, while Chiastopsylla rossi fleas did not differ in size between fragments and natural areas. The differential response of the 2 flea species may reflect the strength of association between the host and parasite, with the former spending a greater proportion of its lifespan on the host. Therefore, in this study agriculture fragments provide better conditions for both an opportunistic rodent and a closely associated flea species. PMID:23101765

  19. Demographic comparison of sweetpotato weevil reared on a major host, Ipomoea batatas, and an alternative host, I. triloba

    PubMed Central

    Reddy, Gadi V. P.; Chi, Hisn

    2015-01-01

    In this study, we collected life table data for the sweetpotato weevil, Cylas formicarius, grown on Ipomoea batatas and Ipomoea triloba, and analyzed them using an age-stage, two-sex life table. We also demonstrated the growth potential of C. formicarius on these two host plants by using population projection. These data will be useful to the growers to the selection or eradication of host plants in an integrated control strategy for C. formicarius for the entire area of the targeted areas. We found that C. formicarius developed faster on I. batatas than on I. triloba. The developmental times of the larval and pupal stages on I. batatas than on I. triloba were 37.01 and 8.3 days. The adult females emerged before and began to produce eggs at 42 days earlier when reared on I. batatas. The fecundity of females was 90.0 eggs on I. batatas significantly higher than the mean fecundity of 68.5 eggs on I. triloba. Although this insect has a higher intrinsic rate of increase on I. batatas, the study indicated that C. formicarius can successfully survive and reproduce on both host plants. PMID:26156566

  20. Interpretation of drug concentrations in an alternative matrix: the case of meprobamate in vitreous humor.

    PubMed

    Bévalot, Fabien; Gustin, Marie-Paule; Cartiser, Nathalie; Le Meur, Catherine; Malicier, Daniel; Fanton, Laurent

    2011-05-01

    The use of vitreous humor (VH) as an alternative matrix to blood in the field of forensic toxicology has been described for numerous drugs. Interpretation of drug concentrations measured in VH, as in other matrices, requires statistical analysis of a data set obtained on a significant series. In the present study, two diagnostic tests interpreting postmortem VH concentrations of meprobamate in 117 sets of autopsy data are reported. (1) A VH meprobamate concentration threshold of 28 mg/l was statistically equivalent to that of blood meprobamate concentration threshold of 50 mg/l distinguishing overdose from therapeutic use in blood. The intrinsic qualities of the test were good, with sensitivity of 0.95 and absolute specificity of 1. (2) A novel interpretation tool is proposed, allowing blood concentration range to be evaluated, with a known probability, from VH concentration. PMID:21337124

  1. Nuclear matrix protein Matrin3 regulates alternative splicing and forms overlapping regulatory networks with PTB

    PubMed Central

    Coelho, Miguel B; Attig, Jan; Bellora, Nicolás; König, Julian; Hallegger, Martina; Kayikci, Melis; Eyras, Eduardo; Ule, Jernej; Smith, Christopher WJ

    2015-01-01

    Matrin3 is an RNA- and DNA-binding nuclear matrix protein found to be associated with neural and muscular degenerative diseases. A number of possible functions of Matrin3 have been suggested, but no widespread role in RNA metabolism has yet been clearly demonstrated. We identified Matrin3 by its interaction with the second RRM domain of the splicing regulator PTB. Using a combination of RNAi knockdown, transcriptome profiling and iCLIP, we find that Matrin3 is a regulator of hundreds of alternative splicing events, principally acting as a splicing repressor with only a small proportion of targeted events being co-regulated by PTB. In contrast to other splicing regulators, Matrin3 binds to an extended region within repressed exons and flanking introns with no sharply defined peaks. The identification of this clear molecular function of Matrin3 should help to clarify the molecular pathology of ALS and other diseases caused by mutations of Matrin3. PMID:25599992

  2. Tenebrio molitor (Coleoptera: Tenebrionidae) as an alternative host to study fungal infections.

    PubMed

    de Souza, Patrícia Canteri; Morey, Alexandre Tadachi; Castanheira, Gabriel Marcondes; Bocate, Karla Paiva; Panagio, Luciano Aparecido; Ito, Fabio Augusto; Furlaneto, Márcia Cristina; Yamada-Ogatta, Sueli Fumie; Costa, Idessânia Nazareth; Mora-Montes, Hector Manuel; Almeida, Ricardo Sergio

    2015-11-01

    Models of host–pathogen interactions are crucial for the analysis of microbial pathogenesis. In this context, invertebrate hosts, including Drosophila melanogaster (fruit fly), Caenorhabditis elegans (nematode) and Galleria mellonella (moth), have been used to study the pathogenesis of fungi and bacteria. Each of these organisms offers distinct benefits in elucidating host–pathogen interactions. In this study,we present a newinvertebrate infection model to study fungal infections: the Tenebrio molitor (beetle) larvae. Here we performed T. molitor larvae infection with one of two important fungal human pathogens, Candida albicans or Cryptococcus neoformans, and analyzed survival curves and larva infected tissues.We showed that increasing concentrations of inoculum of both fungi resulted in increased mortality rates, demonstrating the efficiency of the method to evaluate the virulence of pathogenic yeasts. Additionally, following 12 h post-infection, C. albicans formsmycelia, spreading its hyphae through the larva tissue,whilst GMS stain enabled the visualization of C. neoformans yeast and theirmelanin capsule. These larvae are easier to cultivate in the laboratory than G. mellonella larvae, and offer the same benefits. Therefore, this insect model could be a useful alternative tool to screen clinical pathogenic yeast strainswith distinct virulence traits or different mutant strains. PMID:26453946

  3. Century-old Mystery of Puccinia striiformis Life History Solved with the Identification of Berberis as an Alternate Host

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The life history of Puccinia striiformis remains a mystery because the alternate host has never been found. Inoculation of grasses using aeciospores from naturally infected Berberis chinensis and B. koreana resulted in infection on Poa pratensis, producing uredinia typical of stripe rust caused by P...

  4. Role of Berberis spp. as alternate hosts in generating new races of Puccinia graminis and P. striiformis

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The common barberry and several other Berberis spp. serve as the alternate hosts to two important rust pathogens of small grains and grasses, Puccinia graminis and P. striiformis. Barberry eradication has been practiced for centuries as a means to control stem rust. Diverse virulence variations have...

  5. CD44 alternative splicing in gastric cancer cells is regulated by culture dimensionality and matrix stiffness.

    PubMed

    Branco da Cunha, Cristiana; Klumpers, Darinka D; Koshy, Sandeep T; Weaver, James C; Chaudhuri, Ovijit; Seruca, Raquel; Carneiro, Fátima; Granja, Pedro L; Mooney, David J

    2016-08-01

    Two-dimensional (2D) cultures often fail to mimic key architectural and physical features of the tumor microenvironment. Advances in biomaterial engineering allow the design of three-dimensional (3D) cultures within hydrogels that mimic important tumor-like features, unraveling cancer cell behaviors that would not have been observed in traditional 2D plastic surfaces. This study determined how 3D cultures impact CD44 alternative splicing in gastric cancer (GC) cells. In 3D cultures, GC cells lost expression of the standard CD44 isoform (CD44s), while gaining CD44 variant 6 (CD44v6) expression. This splicing switch was reversible, accelerated by nutrient shortage and delayed at lower initial cell densities, suggesting an environmental stress-induced response. It was further shown to be dependent on the hydrogel matrix mechanical properties and accompanied by the upregulation of genes involved in epithelial-mesenchymal transition (EMT), metabolism and angiogenesis. The 3D cultures reported here revealed the same CD44 alternative splicing pattern previously observed in human premalignant and malignant gastric lesions. These findings indicate that fundamental features of 3D cultures - such as soluble factors diffusion and mechanical cues - influence CD44 expression in GC cells. Moreover, this study provides a new model system to study CD44 dysfunction, whose role in cancer has been in the spotlight for decades. PMID:27187279

  6. Polyfluorides and Neat Fluorine as Host Material in Matrix-Isolation Experiments.

    PubMed

    Brosi, Felix; Vent-Schmidt, Thomas; Kieninger, Stefanie; Schlöder, Tobias; Beckers, Helmut; Riedel, Sebastian

    2015-11-01

    The use of neat fluorine in matrix isolation is reported, as well as the formation of polyfluoride monoanions under cryogenic conditions. Purification procedures and spectroscopic data of fluorine are described, and matrix shifts of selected molecules and impurities in solid fluorine are compared to those of common matrix gases (Ar, Kr, N2 , Ne). The reaction of neat fluorine and IR-laser ablated metal atoms to yield fluorides of chromium (CrF5 ), palladium (PdF2 ), gold (AuF5 ), and praseodymium (PrF4 ) has been investigated. The fluorides have been characterized in solid fluorine by IR spectroscopy at 5 K. Also the fluorination of Kr and the photo-dismutation of XeO4 have been studied by using IR spectroscopy in neat fluorine. Formation of the [F5 ](-) ion was obtained by IR-laser ablation of platinum in the presence of fluorine and proven in a Ne matrix at 5 K by two characteristic vibrational bands of [F5 ](-) at $\\tilde \

  7. Tetrahymena: An Alternative Model Host for Evaluating Virulence of Aeromonas Strains

    PubMed Central

    Pang, Mao-Da; Lin, Xiao-Qin; Hu, Meng; Li, Jing; Lu, Cheng-Ping; Liu, Yong-Jie

    2012-01-01

    An easier assessment model would be helpful for high-throughput screening of Aeromonas virulence. The previous study indicated the potential of Tetrahymena as a permissive model to examine virulence of Aeromonas hydrophila. Here our aim was to assess virulence of Aeromonas spp. using two model hosts, a zebrafish assay and Tetrahymena-Aeromonas co-culture, and to examine whether data from the Tetrahymena thermophila model reflects infections in the well-established animal model. First, virulence of 39 Aeromonas strains was assessed by determining the 50% lethal dose (LD50) in zebrafish. LD50 values ranging from 1.3×102 to 3.0×107 indicated that these strains represent a high to moderate degree of virulence and could be useful to assess virulence in the Tetrahymena model. In Tetrahymena-Aeromonas co-culture, we evaluated the virulence of Aeromonas by detecting relative survival of Aeromonas and Tetrahymena. An Aeromonas isolate was considered virulent when its relative survival was greater than 60%, while the Aeromonas isolate was considered avirulent if its relative survival was below 40%. When relative survival of T. thermophila was lower than 40% after co-culture with an Aeromonas isolate, the bacterial strain was regarded as virulent. In contrast, the strain was classified as avirulent if relative survival of T. thermophila was greater than 50%. Encouragingly, data from the 39 Aeromonas strains showed good correlation in zebrafish and Tetrahymena-Aeromonas co-culture models. The results provide sufficient data to demonstrate that Tetrahymena can be a comparable alternative to zebrafish for determining the virulence of Aeromonas isolates. PMID:23145022

  8. A Bacterial Pathogen uses Distinct Type III Secretion Systems to Alternate between Host Kingdom

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Gram-negative bacterial pathogens of eukaryotes often secrete proteins directly into host cells via a needle-like protein channel called a ‘type III secretion system’ (T3SS). Bacteria that are adapted to either animal or plant hosts use phylogenetically distinct T3SSs for secreting proteins. Here, ...

  9. Volatile fragrances associated with flowers mediate the host plant alternation of a polyphagous mirid bug

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Apolygus lucorum (Meyer-Dür) (Hemiptera: Miridae) is an important insect pest of cotton, fruit trees and other crops in China, and exhibits a particularly broad host range. Adult A. lucorum greatly prefers host plants at the flowering stage, and their populations track flowering plants both spatiall...

  10. Music as Engaging, Educational Matrix: Exploring the Case of Marginalised Students Attending an "Alternative" Music Industry School

    ERIC Educational Resources Information Center

    Cleaver, David; Riddle, Stewart

    2014-01-01

    "Harmony High" is an alternative school where music functions as an educational magnet to attract marginalised students who have disengaged from the mainstream. Through an investigation of the student perspective, we discover that while acting as a magnet, music also becomes the educational matrix or "heart and soul" that helps…

  11. Immigration of susceptible hosts triggers the evolution of alternative parasite defence strategies.

    PubMed

    Chabas, Hélène; van Houte, Stineke; Høyland-Kroghsbo, Nina Molin; Buckling, Angus; Westra, Edze R

    2016-08-31

    Migration of hosts and parasites can have a profound impact on host-parasite ecological and evolutionary interactions. Using the bacterium Pseudomonas aeruginosa UCBPP-PA14 and its phage DMS3vir, we here show that immigration of naive hosts into coevolving populations of hosts and parasites can influence the mechanistic basis underlying host defence evolution. Specifically, we found that at high levels of bacterial immigration, bacteria switched from clustered regularly interspaced short palindromic repeats (CRISPR-Cas) to surface modification-mediated defence. This effect emerges from an increase in the force of infection, which tips the balance from CRISPR to surface modification-based defence owing to the induced and fixed fitness costs associated with these mechanisms, respectively. PMID:27581884

  12. Host-derived Loss of Dentin Matrix Stiffness Associated with Solubilization of Collagen

    PubMed Central

    Carrilho, Marcela R.; Tay, Franklin R.; Donnelly, Adam M.; Agee, Kelli A.; Tjäderhane, Leo; Mazzoni, Annalisa; Breschi, Lorenzo; Foulger, Stephen; Pashley, David H.

    2009-01-01

    Matrix metalloproteinases (MMPs) bound to dentin matrices are activated during adhesive bonding procedures and are thought to contribute to the progressive degradation of resin-dentin bonds over time. The purpose of this study was to evaluate the changes in mechanical, biochemical and structural properties of demineralized dentin treated with or without chlorhexidine (CHX), a known MMP-inhibitor. After demineralizing dentin beams in EDTA or phosphoric acid (PA), the baseline modulus of elasticity (E) of each beam was measured by 3-point flexure. Specimens were pretreated with water (control) or with 2% CHX (experimental) and then incubated in artificial saliva (AS) at 37°C for 4 weeks. The E of each specimen was remeasured weekly and, the media was analyzed for solubilized dentin collagen at first and fourth week of incubation. Some specimens were processed for electron microscopy (TEM) immediately after demineralization and after 4 weeks of incubation. In EDTA and PA-demineralized specimens, the E of the control specimens fell (p<0.05) after incubation in AS, while there were no changes in E in the CHX-pretreated specimens over time. More collagen was solubilized from PA-demineralized controls (p<0.05) than from EDTA-demineralized matrices after 1 or 4 weeks. Less collagen (p<0.05) was solubilized from CHX-pretreated specimens demineralized in EDTA compared to PA. TEM examination of control beams revealed that prolonged demineralization of dentin in 10% PA (12 h) did not denature the collagen fibrils. PMID:19090493

  13. The life cycle of Ceratomyxa shasta, a myxosporean parasite of salmonids, requires a freshwater polychaete as an alternate host.

    PubMed

    Bartholomew, J L; Whipple, M J; Stevens, D G; Fryer, J L

    1997-10-01

    The actinosporean life stage of Ceratomyxa shasta, a myxozoan parasite of salmonids, and the annelid worm that serves as its alternate host were identified in laboratory transmission experiments and their roles were confirmed using molecular techniques. Infection by the parasite occurred in susceptible fish that were either exposed to or force fed the freshwater polychaete, Manayunkia speciosa, infected with the actinosporean. These observations were confirmed using the polymerase chain reaction with primers designed from the C. shasta 18S rDNA sequence. DNA was amplified from polychaetes harboring the actinosporean that caused infection in the fish but not from uninfected polychaetes. Amplified DNA from an infected polychaete was sequenced and its homology with the 18S rDNA sequence of C. shasta spores verified the proposed life cycle. Ultrastructural examination of the actinosporean in the polychaete showed developmental stages in the epidermis rather than within the intestinal epithelium as described for other myxozoans. The methods described will be useful in identifying alternate hosts and morphologically diverse life stages in the complex life cycles of other myxosporea and in understanding the relationships between these parasites and their hosts. PMID:9379291

  14. An Alternative Method for Computing Mean and Covariance Matrix of Some Multivariate Distributions

    ERIC Educational Resources Information Center

    Radhakrishnan, R.; Choudhury, Askar

    2009-01-01

    Computing the mean and covariance matrix of some multivariate distributions, in particular, multivariate normal distribution and Wishart distribution are considered in this article. It involves a matrix transformation of the normal random vector into a random vector whose components are independent normal random variables, and then integrating…

  15. A bacterial pathogen uses distinct type III secretion systems to alternate between host kingdoms

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Plant and animal-pathogenic bacteria utilize phylogenetically distinct type III secretion systems (T3SS) that produce needle-like injectisomes or pili for the delivery of effector proteins into host cells. Pantoea stewartii subsp. stewartii (Pnss), the causative agent of Stewart’s bacterial wilt and...

  16. Midgut serine proteases and alternative host plant utilization in Pieris brassicae L.

    PubMed Central

    Kumar, Rakesh; Bhardwaj, Usha; Kumar, Pawan; Mazumdar-Leighton, Sudeshna

    2015-01-01

    Pieris brassicae L. is a serious pest of cultivated crucifers in several parts of the world. Larvae of P. brassicae also feed prolifically on garden nasturtium (Tropaeolum majus L., of the family Tropaeolaceae). Proteolytic digestion was studied in larvae feeding on multiple hosts. Fourth instars were collected from cauliflower fields before transfer onto detached, aerial tissues of selected host plants in the lab. Variable levels of midgut proteases were detected in larvae fed on different hosts using protein substrates (casein and recombinant RBCL cloned from cauliflower) and diagnostic, synthetic substrates. Qualitative changes in midgut trypsin activities and quantitative changes in midgut chymotrypsin activities were implicated in physiological adaptation of larvae transferred to T. majus. Midgut proteolytic activities were inhibited to different extents by serine protease inhibitors, including putative trypsin inhibitors isolated from herbivore-attacked and herbivore-free leaves of cauliflower (CfTI) and T. majus (TpTI). Transfer of larvae to T. majus significantly influenced feeding parameters but not necessarily when transferred to different tissues of the same host. Results obtained are relevant for devising sustainable pest management strategies, including transgenic approaches using genes encoding plant protease inhibitors. PMID:25873901

  17. Volatile fragrances associated with flowers mediate host plant alternation of a polyphagous mirid bug

    PubMed Central

    Pan, Hongsheng; Lu, Yanhui; Xiu, Chunli; Geng, Huihui; Cai, Xiaoming; Sun, Xiaoling; Zhang, Yongjun; Williams III, Livy; Wyckhuys, Kris A. G.; Wu, Kongming

    2015-01-01

    Apolygus lucorum (Hemiptera: Miridae) is an important insect pest of cotton and fruit trees in China. The adults prefer host plants at the flowering stage, and their populations track flowering plants both spatially and temporally. In this study, we examine whether flower preference of its adults is mediated by plant volatiles, and which volatile compositions play an important role in attracting them. In olfactometer tests with 18 key host species, the adults preferred flowering plants over non-flowering plants of each species. Coupled gas chromatography-electroantennography revealed the presence of seven electrophysiologically active compounds from flowering plants. Although the adults responded to all seven synthetic plant volatiles in electroantennography tests, only four (m-xylene, butyl acrylate, butyl propionate and butyl butyrate) elicited positive behavioral responses in Y-tube olfactometer bioassays. The adults were strongly attracted to these four active volatiles in multi-year laboratory and field trials. Our results suggest that these four fragrant volatiles, which are emitted in greater amounts once plants begin to flower, mediate A. lucorum’s preference to flowering host plants. We proved that the use of commonly occurring plant volatiles to recognize a large range of plant species can facilitate host selection and preference of polyphagous insect herbivore. PMID:26423224

  18. Volatile fragrances associated with flowers mediate host plant alternation of a polyphagous mirid bug.

    PubMed

    Pan, Hongsheng; Lu, Yanhui; Xiu, Chunli; Geng, Huihui; Cai, Xiaoming; Sun, Xiaoling; Zhang, Yongjun; Williams Iii, Livy; Wyckhuys, Kris A G; Wu, Kongming

    2015-01-01

    Apolygus lucorum (Hemiptera: Miridae) is an important insect pest of cotton and fruit trees in China. The adults prefer host plants at the flowering stage, and their populations track flowering plants both spatially and temporally. In this study, we examine whether flower preference of its adults is mediated by plant volatiles, and which volatile compositions play an important role in attracting them. In olfactometer tests with 18 key host species, the adults preferred flowering plants over non-flowering plants of each species. Coupled gas chromatography-electroantennography revealed the presence of seven electrophysiologically active compounds from flowering plants. Although the adults responded to all seven synthetic plant volatiles in electroantennography tests, only four (m-xylene, butyl acrylate, butyl propionate and butyl butyrate) elicited positive behavioral responses in Y-tube olfactometer bioassays. The adults were strongly attracted to these four active volatiles in multi-year laboratory and field trials. Our results suggest that these four fragrant volatiles, which are emitted in greater amounts once plants begin to flower, mediate A. lucorum's preference to flowering host plants. We proved that the use of commonly occurring plant volatiles to recognize a large range of plant species can facilitate host selection and preference of polyphagous insect herbivore. PMID:26423224

  19. Bacillus thuringiensis-toxin resistance management: Stable isotope assessment of alternate host use by Helicoverpa zea

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Data have been lacking on the proportion of H. zea larvae that develop on non-cotton host plants that can serve as a refuge from selection pressure for adaptation to Bt-cotton. We found that individual H. zea moths that develop as larvae on cotton and other plants with C3 physiology have a differen...

  20. Genetic Diversity and Host Alternation of the Egg Parasitoid Ooencyrtus pityocampae between the Pine Processionary Moth and the Caper Bug

    PubMed Central

    Samra, Shahar; Ghanim, Murad; Protasov, Alex; Branco, Manuela; Mendel, Zvi

    2015-01-01

    The increased use of molecular tools for species identification in recent decades revealed that each of many apparently generalist parasitoids are actually a complex of morphologically similar congeners, most of which have a rather narrow host range. Ooencyrtus pityocampae (OP), an important egg parasitoid of the pine processionary moth (PPM), is considered a generalist parasitoid. OP emerges from PPM eggs after winter hibernation, mainly in spring and early summer, long before the eggs of the next PPM generation occurs. The occurrence of OP in eggs of the variegated caper bug (CB) Stenozygum coloratum in spring and summer suggests that OP populations alternate seasonally between PPM and CB. However, the identity of OP population on CB eggs seemed uncertain; unlike OP-PPM populations, the former displayed apparently high male/female ratios and lack of attraction to the PPM sex pheromone. We studied the molecular identities of the two populations since the morphological identification of the genus Ooencyrtus, and OP in particular, is difficult. Sequencing of COI and ITS2 DNA fragments and AFLP analysis of individuals from both hosts revealed no apparent differences between the OP-PPM and the OP-CB populations for both the Israeli and the Turkish OPs, which therefore supported the possibility of host alternation. Sequencing data extended our knowledge of the genetic structure of OP populations in the Mediterranean area, and revealed clear separation between East and West Mediterranean populations. The overall level of genetic diversity was rather small, with the Israeli population much less diverse than all others; possible explanations for this finding are discussed. The findings support the possibility of utilizing the CB and other hosts for enhancing biological control of the PPM. PMID:25856082

  1. CTXϕ: Exploring new alternatives in host factor-mediated filamentous phage replications.

    PubMed

    Martínez, Eriel; Campos-Gómez, Javier; Barre, François-Xavier

    2016-01-01

    For a long time Ff phages from Escherichia coli provided the majority of the knowledge about the rolling circle replication mechanism of filamentous phages. Host factors involved in coliphages replication have been fully identified. Based on these studies, the function of Rep protein as the accessory helicase directly implicated in filamentous phage replication was considered a paradigm. We recently reported that the replication of some filamentous phages from Vibrio cholerae, including the cholera toxin phage CTXϕ, depended on the accessory helicase UvrD instead of Rep. We also identified HU protein as one of the host factors involved in CTXϕ and VGJϕ replication. The requirement of UvrD and HU for rolling circle replication was previously reported in some family of plasmids but had no precedent in filamentous phages. Here, we enrich the discussion of our results and present new preliminary data highlighting remarkable divergence in the lifestyle of filamentous phages. PMID:27607139

  2. A histologic study of the extracellular matrix during the development of glomerulosclerosis in murine chronic graft-versus-host disease.

    PubMed Central

    Bergijk, E. C.; Munaut, C.; Baelde, J. J.; Prins, F.; Foidart, J. M.; Hoedemaeker, P. J.; Bruijn, J. A.

    1992-01-01

    The development of glomerulosclerosis was studied in murine chronic graft-versus-host disease (GvHD), which is a model for human systemic lupus erythematosus. The authors investigated the distribution patterns of six components of the extracellular matrix (ECM), i.e., laminin, fibronectin, collagen types I, III, IV, and VI during the course of the disease. All of these ECM components except collagen type I were found in the glomeruli of normal mice, where all of them were intrinsic constituents of the mesangium. Laminin, fibronectin, and collagen type IV were also found in the glomerular capillary walls. Starting 6 weeks after the induction of GvHD and continuing at week 8, the onset of an expansion of the mesangial matrix was observed. At the same time, the amounts of laminin, fibronectin, and collagen types IV and VI increased. Ten weeks after the onset of the disease, glomerulosclerosis developed. Traces of the interstitial collagen type I were found in sclerotic glomeruli. The levels of four ECM components, i.e., collagens III, IV, VI, and laminin were markedly decreased in the sclerotic glomeruli as compared with week 8. In contrast, the amount of fibronectin in the sclerotic glomeruli increased dramatically. Immunoelectron microscopic examination showed fibronectin in the sclerotic lesions, in contrast to laminin, collagen type I, and collagen type IV. It is concluded that the sclerotic lesions in murine chronic GvHD contain fibronectin. The small amounts of the ECM components laminin, as well as collagens III, IV, and VI in the sclerotic glomeruli in GvHD, might represent remnants of mesangial material and collapsed capillary walls. These components are probably replaced by increased production and/or accumulation of collagen type I and fibronectin. Images Figure 2 Figure 1 Figure 3 Figure 4 Figure 5 Figure 6 PMID:1580327

  3. New Host Factors Important for Respiratory Syncytial Virus (RSV) Replication Revealed by a Novel Microfluidics Screen for Interactors of Matrix (M) Protein*

    PubMed Central

    Kipper, Sarit; Hamad, Samar; Caly, Leon; Avrahami, Dorit; Bacharach, Eran; Jans, David A.; Gerber, Doron; Bajorek, Monika

    2015-01-01

    Although human respiratory syncytial virus (RSV) is the most common cause of bronchiolitis and pneumonia in infants and elderly worldwide, there is no licensed RSV vaccine or effective drug treatment available. The RSV Matrix protein plays key roles in virus life cycle, being found in the nucleus early in infection in a transcriptional inhibitory role, and later localizing in viral inclusion bodies before coordinating viral assembly and budding at the plasma membrane. In this study, we used a novel, high throughput microfluidics platform and custom human open reading frame library to identify novel host cell binding partners of RSV matrix. Novel interactors identified included proteins involved in host transcription regulation, the innate immunity response, cytoskeletal regulation, membrane remodeling, and cellular trafficking. A number of these interactions were confirmed by immunoprecipitation and cellular colocalization approaches. Importantly, the physiological significance of matrix interaction with the actin-binding protein cofilin 1, caveolae protein Caveolin 2, and the zinc finger protein ZNF502 was confirmed. siRNA knockdown of the host protein levels resulted in reduced RSV virus production in infected cells. These results have important implications for future antiviral strategies aimed at targets of RSV matrix in the host cell. PMID:25556234

  4. Lytic infection of Lactococcus lactis by bacteriophages Tuc2009 and c2 triggers alternative transcriptional host responses.

    PubMed

    Ainsworth, Stuart; Zomer, Aldert; Mahony, Jennifer; van Sinderen, Douwe

    2013-08-01

    Here we present an entire temporal transcriptional profile of Lactococcus lactis subsp. cremoris UC509.9 undergoing lytic infection with two distinct bacteriophages, Tuc2009 and c2. Furthermore, corresponding high-resolution whole-phage genome tiling arrays of both bacteriophages were performed throughout lytic infection. Whole-genome microarrays performed at various time points postinfection demonstrated a rather modest impact on host transcription. The majority of changes in the host transcriptome occur during late infection stages; few changes in host gene transcription occur during the immediate and early infection stages. Alterations in the L. lactis UC509.9 transcriptome during lytic infection appear to be phage specific, with relatively few differentially transcribed genes shared between cells infected with Tuc2009 and those infected with c2. Despite the apparent lack of a coordinated general phage response, three themes common to both infections were noted: alternative transcription of genes involved in catabolic flux and energy production, differential transcription of genes involved in cell wall modification, and differential transcription of genes involved in the conversion of ribonucleotides to deoxyribonucleotides. The transcriptional profiles of both bacteriophages during lytic infection generally correlated with the findings of previous studies and allowed the confirmation of previously predicted promoter sequences. In addition, the host transcriptional response to lysogenization with Tuc2009 was monitored along with tiling array analysis of Tuc2009 in the lysogenic state. Analysis identified 44 host genes with altered transcription during lysogeny, 36 of which displayed levels of transcription significantly reduced from those for uninfected cells. PMID:23728817

  5. Initial Larval Feeding on an Alternate Host Enhances Western Corn Rootworm (Coleoptera: Chrysomelidae) Beetle Emergence on Cry3Bb1-Expressing Maize

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The potential for rootworm larvae to move between grassy weeds and transgenic maize may be important in resistance management of transgenic rootworm-resistant maize. To determine the impact of initial feeding of rootworm larvae on alternate hosts, followed by switching host to transgenic maize, on ...

  6. Novel hierarchically porous carbon materials obtained from natural biopolymer as host matrixes for lithium-sulfur battery applications.

    PubMed

    Zhang, Bin; Xiao, Min; Wang, Shuanjin; Han, Dongmei; Song, Shuqin; Chen, Guohua; Meng, Yuezhong

    2014-08-13

    Novel hierarchically porous carbon materials with very high surface areas, large pore volumes and high electron conductivities were prepared from silk cocoon by carbonization with KOH activation. The prepared novel porous carbon-encapsulated sulfur composites were fabricated by a simple melting process and used as cathodes for lithium sulfur batteries. Because of the large surface area and hierarchically porous structure of the carbon material, soluble polysulfide intermediates can be trapped within the cathode and the volume expansion can be alleviated effectively. Moreover, the electron transport properties of the carbon materials can provide an electron conductive network and promote the utilization rate of sulfur in cathode. The prepared carbon-sulfur composite exhibited a high specific capacity and excellent cycle stability. The results show a high initial discharge capacity of 1443 mAh g(-1) and retain 804 mAh g(-1) after 80 discharge/charge cycles at a rate of 0.5 C. A Coulombic efficiency retained up to 92% after 80 cycles. The prepared hierarchically porous carbon materials were proven to be an effective host matrix for sulfur encapsulation to improve the sulfur utilization rate and restrain the dissolution of polysulfides into lithium-sulfur battery electrolytes. PMID:25025228

  7. Expression of most matrix metalloproteinase family members in breast cancer represents a tumor-induced host response.

    PubMed Central

    Heppner, K. J.; Matrisian, L. M.; Jensen, R. A.; Rodgers, W. H.

    1996-01-01

    Matrix metalloproteinase (MMP) family members have been associated with advanced-stage cancer and contribute to tumor progression, invasion, and metastasis as determined by inhibitor studies. In situ hybridization was performed to analyze the expression and localization of all known MMPs in a series of human breast cancer biopsy specimens. Most MMPs were localized to tumor stroma, and all MMPs had very distinct expression patterns. Matrilysin was expressed by morphologically normal epithelial ducts within tumors and in tissue from reduction mammoplasties, and by epithelial-derived tumor cells. Many family members, including stromelysin-3, gelatinase A, MT-MMP, interstitial collagenase, and stromelysin-1 were localized to fibroblasts of tumor stroma of invasive cancers but in quite distinct, and generally widespread, patterns. Gelatinase B, collagenase-3, and metalloelastase expression were more focal; gelatinase B was primarily localized to endothelial cells, collagenase-3 to isolated tumor cells, and metalloelastase to cytokeratin-negative, macrophage-like cells. The MMP inhibitor, TIMP-1, was expressed in both stromal and tumor components in most tumors, and neither stromelysin-2 nor neutrophil collagenase were detected in any of the tumors. These results indicate that there is very tight and complex regulation in the expression of MMP family members in breast cancer that generally represents a host response to the tumor and emphasize the need to further evaluate differential functions for MMP family members in breast tumor progression. Images Figure 1 Figure 2 Figure 3 PMID:8686751

  8. Matrix metalloproteinase-9 deficiency impairs host defense mechanisms against Streptococcus pneumoniae in a mouse model of bacterial meningitis.

    PubMed

    Böttcher, Tobias; Spreer, Annette; Azeh, Ivo; Nau, Roland; Gerber, Joachim

    2003-03-01

    Matrix metalloproteinase-9 (MMP-9) appears to contribute to blood-brain barrier damage and neuronal injury in bacterial meningitis. To further explore the function of MMP-9 in meningeal inflammation, we injected 10(4) colony forming units (CFU) of a Streptoccocus pneumoniae type 3 strain into the right forebrain of MMP-9 deficient mice (MMP-9(-/-), n=16) and wild-type controls (129 x B6, n=15). The clinical course of the disease, leukocyte recruitment into the subarachnoid space and bacterial titers in the brain did not differ. Yet, clearance of the bacteria from blood (log CFU/ml 4.7 [3.8/5.4] vs. 3.6 [3.0/4.0]; P=0.005) and spleen homogenates (log CFU/ml 5.3 [4.8/5.5] vs. 4.0 [2.8/4.7]; P=0.01) was reduced in MMP-9 deficient mice. A reduced systemic bacterial clearance of MMP-9(-/-) mice was confirmed in experimental S. pneumoniae peritonitis/sepsis. This implies a compromised systemic, but not intracerebral host response against S. pneumoniae in MMP-9 deficiency. PMID:12581831

  9. Xylem structure of four grape varieties and 12 alternative hosts to the xylem-limited bacterium Xylella fastidious

    PubMed Central

    Chatelet, David S.; Wistrom, Christina M.; Purcell, Alexander H.; Rost, Thomas L.; Matthews, Mark A.

    2011-01-01

    Background and Aims The bacterium Xylella fastidiosa (Xf), responsible for Pierce's disease (PD) of grapevine, colonizes the xylem conduits of vines, ultimately killing the plant. However, Vitis vinifera grapevine varieties differ in their susceptibility to Xf and numerous other plant species tolerate Xf populations without showing symptoms. The aim of this study was to examine the xylem structure of grapevines with different susceptibilities to Xf infection, as well as the xylem structure of non-grape plant species that support or limit movement of Xf to determine if anatomical differences might explain some of the differences in susceptibility to Xf. Methods Air and paint were introduced into leaves and stems to examine the connectivity between stem and leaves and the length distribution of their vessels. Leaf petiole and stem anatomies were studied to determine the basis for the free or restricted movement of Xf into the plant. Key Results There were no obvious differences in stem or petiole vascular anatomy among the grape varieties examined, nor among the other plant species that would explain differences in resistance to Xf. Among grape varieties, the more tolerant ‘Sylvaner’ had smaller stem vessel diameters and 20 % more parenchyma rays than the other three varieties. Alternative hosts supporting Xf movement had slightly longer open xylem conduits within leaves, and more connection between stem and leaves, when compared with alternative hosts that limit Xf movement. Conclusions Stem–leaf connectivity via open xylem conduits and vessel length is not responsible for differences in PD tolerance among grape varieties, or for limiting bacterial movement in the tolerant plant species. However, it was found that tolerant host plants had narrower vessels and more parenchyma rays, possibly restricting bacterial movement at the level of the vessels. The implications of xylem structure and connectivity for the means and regulation of bacterial movement are

  10. Leishmania amazonensis promastigotes in 3D Collagen I culture: an in vitro physiological environment for the study of extracellular matrix and host cell interactions

    PubMed Central

    Rodrigues, Juliany C.F.; Viana, Nathan B.; Pontes, Bruno; Pereira, Camila F.A.; Silva-Filho, Fernando C.

    2014-01-01

    Leishmania amazonensis is the causative agent of American cutaneous leishmaniasis, an important neglected tropical disease. Once Leishmania amazonensis is inoculated into the human host, promastigotes are exposed to the extracellular matrix (ECM) of the dermis. However, little is known about the interaction between the ECM and Leishmania promastigotes. In this study we established L. amazonensis promastigote culture in a three-dimensional (3D) environment mainly composed of Collagen I (COL I). This 3D culture recreates in vitro some aspects of the human host infection site, enabling the study of the interaction mechanisms of L. amazonensis with the host ECM. Promastigotes exhibited “freeze and run” migration in the 3D COL I matrix, which is completely different from the conventional in vitro swimming mode of migration. Moreover, L. amazonensis promastigotes were able to invade, migrate inside, and remodel the 3D COL I matrix. Promastigote trans-matrix invasion and the freeze and run migration mode were also observed when macrophages were present in the matrix. At least two classes of proteases, metallo- and cysteine proteases, are involved in the 3D COL I matrix degradation caused by Leishmania. Treatment with a mixture of protease inhibitors significantly reduced promastigote invasion and migration through this matrix. Together our results demonstrate that L. amazonensis promastigotes release proteases and actively remodel their 3D environment, facilitating their migration. This raises the possibility that promastigotes actively interact with their 3D environment during the search for their cellular “home”—macrophages. Supporting this hypothesis, promastigotes migrated faster than macrophages in a novel 3D co-culture model. PMID:24765565

  11. An Alternating Least Squares Method for the Weighted Approximation of a Symmetric Matrix.

    ERIC Educational Resources Information Center

    ten Berge, Jos M. F.; Kiers, Henk A. L.

    1993-01-01

    R. A. Bailey and J. C. Gower explored approximating a symmetric matrix "B" by another, "C," in the least squares sense when the squared discrepancies for diagonal elements receive specific nonunit weights. A solution is proposed where "C" is constrained to be positive semidefinite and of a fixed rank. (SLD)

  12. Comparison of IgG diffusion and extracellular matrix composition in rhabdomyosarcomas grown in mice versus in vitro as spheroids reveals the role of host stromal cells

    PubMed Central

    Davies, C de L; Berk, D A; Pluen, A; Jain, R K

    2002-01-01

    The tumour extracellular matrix acts as a barrier to the delivery of therapeutic agents. To test the hypothesis that extracellular matrix composition governs the penetration rate of macromolecules in tumour tissue, we measured the diffusion coefficient of nonspecific IgG in three rhabdomyosarcoma subclones growing as multicellular spheroids in vitro or as subcutaneous tumours in dorsal windows in vivo. In subcutaneous tumours, the diffusion coefficient decreased with increasing content of collagen and sulphated glycosaminoglycans. When grown as multicellular spheroids, no differences in either extracellular matrix composition or diffusion coefficient were found. Comparison of in vitro vs in vivo results suggests an over-riding role of host stromal cells in extracellular matrix production subjected to modulation by tumour cells. Penetration of therapeutic macromolecules through tumour extracellular matrix might thus be largely determined by the host organ. Hence, caution must be exercised in extrapolating drug penetrability from spheroids and multilayer cellular sandwiches consisting of only tumour cells to tumours in vivo. British Journal of Cancer (2002) 86, 1639–1644. DOI: 10.1038/sj/bjc/6600270 www.bjcancer.com © 2002 Cancer Research UK PMID:12085216

  13. Matrix and position correction of shuffler assays by application of the alternating conditional expectation algorithm to shuffler data

    SciTech Connect

    Pickrell, M M; Rinard, P M

    1992-01-01

    The {sup 252}Cf shuffler assays fissile uranium and plutonium using active neutron interrogation and then counting the induced delayed neutrons. Using the shuffler, we conducted over 1700 assays of 55-gal. drums with 28 different matrices and several different fissionable materials. We measured the drums to dispose the matrix and position effects on {sup 252}Cf shuffler assays. We used several neutron flux monitors during irradiation and kept statistics on the count rates of individual detector banks. The intent of these measurements was to gauge the effect of the matrix independently from the uranium assay. Although shufflers have previously been equipped neutron monitors, the functional relationship between the flux monitor sepals and the matrix-induced perturbation has been unknown. There are several flux monitors so the problem is multivariate, and the response is complicated. Conventional regression techniques cannot address complicated multivariate problems unless the underlying functional form and approximate parameter values are known in advance. Neither was available in this case. To address this problem, we used a new technique called alternating conditional expectations (ACE), which requires neither the functional relationship nor the initial parameters. The ACE algorithm develops the functional form and performs a numerical regression from only the empirical data. We applied the ACE algorithm to the shuffler-assay and flux-monitor data and developed an analytic function for the matrix correction. This function was optimized using conventional multivariate techniques. We were able to reduce the matrix-induced-bias error for homogeneous samples to 12.7%. The bias error for inhomogeneous samples was reduced to 13.5%. These results used only a few adjustable parameters compared to the number of available data points; the data were not over fit,'' but rather the results are general and robust.

  14. An alternative host model of a mixed fungal infection by azole susceptible and resistant Aspergillus spp strains.

    PubMed

    Alcazar-Fuoli, L; Buitrago, Mj; Gomez-Lopez, A; Mellado, E

    2015-01-01

    Aspergillus fumigatus is the most common mold involved in human infections. However, the number of non-fumigatus species able to cause disease is continuously increasing. Among them, Aspergillus lentulus is reported in hematological and cystic fibrosis patients and in those treated with corticosteroids. A. lentulus differs from A. fumigatus in some clinically relevant aspects such as virulence and antifungal susceptibility, showing high MICs to most antifungals. Previous studies proved that A. lentulus was pathogenic in immunocompromised mice, although the course of the infection was delayed compared to A. fumigatus. These differences could explain why A. lentulus is mostly found in mixed infections with A. fumigatus challenging the diagnosis and treatment. We used the alternative model host Galleria mellonella to compare virulence, host interaction, fungal burden and antifungal response when larvae were infected with A. fumigatus or A. lentulus alone, and with a mixture of both species. A. lentulus was pathogenic in G. mellonella but infected larvae did not respond to therapeutic doses of voriconazole. We were able to simultaneously detect A. fumigatus and A. lentulus by a multiplex Nested Real Time PCR (MN-PCR). Comparative analysis of larvae histological sections showed melanization of both species but presented a different pattern of immune response by haemocytes. Analysis of fungal burden and histology showed that A. lentulus survived in the G. mellonella despite the antifungal treatment in single and mixed infections. We conclude that the simultaneous presence of antifungal susceptible and resistant Aspergillus species would likely complicate the management of these infections. PMID:26065322

  15. Using Complementary and Alternative Medicines to Target the Host Response during Severe Influenza

    PubMed Central

    Cai, Charles; Clark, Ian A.

    2010-01-01

    It is now accepted that an overwhelming inflammatory response is the cause of human deaths from avian H5N1 influenza infection. With this in mind we sought to examine the literature for examples of complementary and alternative medicines that reduce inflammation, and to place the results of this search in the context of our own work in a mouse model of influenza disease, using a pharmaceutical agent with anti-inflammatory properties. Two Chinese herbs, Angelica sinensis (Dang Gui) and Salvia miltiorrhiza (Danshen), have been recently shown to protect mice during lethal experimental sepsis via inhibition of the novel inflammatory cytokine High Mobility Group Box 1 protein (HMGB1). Biochanin A, a ligand of the peroxisome proliferator activated receptors (PPAR) alpha and gamma and the active isoflavone in Trifolium pratense (red clover), has anti-inflammatory properties, and thus could be used as an influenza treatment. This is of great interest since we have recently shown that gemfibrozil, a drug used to treat hyperlipidemia in humans and a synthetic ligand of PPAR alpha, significantly reduces the mortality associated with influenza infections in mice. The inflammation-modulating abilities of these natural agents should be considered in light of what is now known about the mechanisms of fatal influenza, and tested as potential candidates for influenza treatments in their own right, or as adjunct treatments to antivirals. PMID:19779008

  16. Effect of gel structure of matrix orientation in pulsed alternating electric fields

    SciTech Connect

    Stellwagen, N.C.; Stellwagen, J.

    1993-12-31

    Four polymeric gels with different structures, LE agarose, HEEO agarose, beta-carrageenan, and polyacrylamide, were studied by transient electric birefringence to determine the importance of various structural features on the orientation of the gels in pulsed alternating electric fields. The birefrigence relaxation times observed for agarose gels in low voltage electric fields suggest that long fibers and/or domains, ranging up to tens of microns in size, are oriented by the electric field. The sign of the birefringence reverses when the direction of the electric field is reversed, suggesting that the oriented domains change their direction of orientation from parallel to perpendicular (or vice versa) when the polarity of the electric field is reversed. These anamalous orientation effects are observed with both types of agarose gels, but not with beta-carrageenan or polyacrylamide gels, suggesting that the alternating D,L galactose residues in the agarose backbone are responsible for the anomalies.

  17. An Alternative Kaposi's Sarcoma-Associated Herpesvirus Replication Program Triggered by Host Cell Apoptosis

    PubMed Central

    Prasad, Alka; Lu, Michael; Lukac, David M.

    2012-01-01

    Kaposi's sarcoma-associated herpesvirus (KSHV) is linked to several neoplastic diseases: Kaposi's sarcoma, primary effusion lymphoma (PEL), and multicentric Castleman's disease (MCD). KSHV replicates actively, via a controlled gene expression program, but can also remain latent. It had been thought that the transition from latent to lytic replication was controlled exclusively by the replication and transcription activator protein RTA (open reading frame 50 [ORF50] gene product). A dominant-negative (DN) ORF50 mutant, ORF50ΔSTAD, blocks gene expression and replication. We produced a PEL cell line derivative containing both latent KSHV genomes and an inducible ORF50ΔSTAD. We unexpectedly found that induction of apoptosis triggered high-level viral replication, even when DN ORF50ΔSTAD was present, suggesting that apoptosis triggers KSHV replication through a distinct RTA-independent pathway. We verified that apoptosis triggers KSHV replication independent of RTA using ORF50 small interfering RNA (siRNA) and also showed that caspase activity is required to trigger KSHV replication. We showed that when apoptosis triggers KSHV replication, the kinetics of late gene expression is accelerated by 12 to 24 h and that virus produced following apoptosis has reduced infectivity. KSHV therefore appears to replicate via two distinct pathways, a conventional pathway requiring RTA, with slower replication kinetics, producing virus with higher infectivity, and an alternative apoptosis-triggered pathway that does not require RTA, has faster replication kinetics, and produces virus with lower infectivity. The existence of a distinct apoptosis-triggered, accelerated replication pathway may have evolutionary advantages for the virus and clinical significance for the treatment of KSHV-associated neoplasms. It also provides further evidence that KSHV can sense and react to its environment. PMID:22345480

  18. Interposition Porcine Acellular Dermal Matrix Xenograft Successful Alternative in Treatment for Massive Rotator Cuff

    PubMed Central

    Neumann, Julie; Zgonis, Miltiadis H.; Reay, Kathleen Dolores; Mayer, Stephanie W.; Boggess, Blake; Toth, Alison P.

    2016-01-01

    Objectives: Despite advances in the surgical techniques of rotator cuff repair (RCR), the management of massive rotator cuff tears in shoulders without glenohumeral arthritis poses a difficult problem for surgeons. Failure of massive rotator cuff repairs range from 20-90% at one to two years postoperatively using arthrography, ultrasound, or magnetic resonance imaging. Additionally, there are inconsistent outcomes reported with debridement alone of massive rotator cuff tears as well as limitations seen with other current methods of operative intervention including arthroplasty and tendon transfers. The purpose of this prospective, comparative study was to determine if the repair of massive rotator cuff tears using an interposition porcine acellular dermal matrix xenograft improves subjective function, pain, range of motion, and strength at greater than two years follow-up. To our knowledge, this is the largest prospective series reporting outcomes of using porcine acellular dermal matrix xenograft as an interposition graft. Methods: Thirty-seven patients (37 shoulders) with an average age of 66 years (range 51-80 years) were prospectively followed for 33 months (range 23-48) following massive RCR using porcine acellular dermal matrix interposition xenograft. Subjective outcomes were measured using the Visual Analog Scale (VAS) pain score (0-10, 0 = no pain), Modified American Shoulder and Elbow Score (M-ASES), and Short-Form12 (SF-12) scores. Preoperative and postoperative objective outcome measures included active range of motion and supraspinatus and infraspinatus manual muscle strength. Postoperative outcome measures included quantitative muscle strength using a dynamometer and static and dynamic ultrasonography to assess the integrity of the repair. Results: Average VAS pain score decreased from 4.5 to 1.1 (P<0.001). Average postoperative M-ASES was 89.23. Average postoperative SF-12 was 52.6. Mean forward flexion, external and internal rotation significantly

  19. Interpretation of drug concentrations in an alternative matrix: the case of meprobamate in bile.

    PubMed

    Fanton, L; Bevalot, F; Gustin, M P; Paultre, C Z; Le Meur, C; Malicier, D

    2009-03-01

    Investigating toxicological causes of death may require alternative matrices when the usual ones are lacking. Whereas forensic toxicology uses bile almost only for xenobiotic screening, a diagnostic test interpreting postmortem bile concentrations of meprobamate is reported. Based on 128 sets of autopsy data, its intrinsic qualities were good, with 0.95 sensitivity and 0.93 specificity. In a French forensic population, the positive and negative predictive factors were 0.90 and 0.97, respectively. It is a useful means of revealing overdoses where blood samples are not available or of confirming blood tests when postmortem redistribution is suspected. PMID:18581126

  20. The agroecological matrix as alternative to the land-sparing/agriculture intensification model

    PubMed Central

    Perfecto, Ivette; Vandermeer, John

    2010-01-01

    Among the myriad complications involved in the current food crisis, the relationship between agriculture and the rest of nature is one of the most important yet remains only incompletely analyzed. Particularly in tropical areas, agriculture is frequently seen as the antithesis of the natural world, where the problem is framed as one of minimizing land devoted to agriculture so as to devote more to conservation of biodiversity and other ecosystem services. In particular, the “forest transition model” projects an overly optimistic vision of a future where increased agricultural intensification (to produce more per hectare) and/or increased rural-to-urban migration (to reduce the rural population that cuts forest for agriculture) suggests a near future of much tropical aforestation and higher agricultural production. Reviewing recent developments in ecological theory (showing the importance of migration between fragments and local extinction rates) coupled with empirical evidence, we argue that there is little to suggest that the forest transition model is useful for tropical areas, at least under current sociopolitical structures. A model that incorporates the agricultural matrix as an integral component of conservation programs is proposed. Furthermore, we suggest that this model will be most successful within a framework of small-scale agroecological production. PMID:20339080

  1. A Large Panel Two-CCD Camera Coordinate System with an Alternate-Eight-Matrix Look-Up Table Algorithm

    NASA Astrophysics Data System (ADS)

    Lin, Chern-Sheng; Lu, An-Tsung; Hsu, Yuen-Chang; Tien, Chuen-Lin; Chen, Der-Chin

    In this study, a novel positioning model of a double-CCD cameras calibration system, with an Alternate-Eight-Matrix (AEM) Look-Up-Table (LUT), was proposed. Two CCD cameras were fixed on both sides of a large scale screen to redeem Field Of View (FOV) problems. The first to the fourth AEMLUT were used to compute the corresponding positions of intermediate blocks on the screen captured by the right side camera. In these AEMLUT for the right side camera, the coordinate mapping data of the target in a specific space were stored in two matrixes, while the gray level threshold values of different position were stored in the others. Similarly, the fifth to the eighth AEMLUT were used to compute the corresponding positions of intermediate blocks on the screen captured by the left side camera. Experimental results showed that the problems of dead angles and non-uniform light fields were solved. In addition, rapid and precision positioning results can be obtained by the proposed method.

  2. Genetic basis and selection for life-history trait plasticity on alternative host plants for the cereal aphid Sitobion avenae.

    PubMed

    Dai, Xinjia; Gao, Suxia; Liu, Deguang

    2014-01-01

    Sitobion avenae (F.) can survive on various plants in the Poaceae, which may select for highly plastic genotypes. But phenotypic plasticity was often thought to be non-genetic, and of little evolutionary significance historically, and many problems related to adaptive plasticity, its genetic basis and natural selection for plasticity have not been well documented. To address these questions, clones of S. avenae were collected from three plants, and their phenotypic plasticity under alternative environments was evaluated. Our results demonstrated that nearly all tested life-history traits showed significant plastic changes for certain S. avenae clones with the total developmental time of nymphs and fecundity tending to have relatively higher plasticity for most clones. Overall, the level of plasticity for S. avenae clones' life-history traits was unexpectedly low. The factor 'clone' alone explained 27.7-62.3% of the total variance for trait plasticities. The heritability of plasticity was shown to be significant in nearly all the cases. Many significant genetic correlations were found between trait plasticities with a majority of them being positive. Therefore, it is evident that life-history trait plasticity involved was genetically based. There was a high degree of variation in selection coefficients for life-history trait plasticity of different S. avenae clones. Phenotypic plasticity for barley clones, but not for oat or wheat clones, was frequently found to be under significant selection. The directional selection of alternative environments appeared to act to decrease the plasticity of S. avenae clones in most cases. G-matrix comparisons showed significant differences between S. avenae clones, as well as quite a few negative covariances (i.e., trade-offs) between trait plasticities. Genetic basis and evolutionary significance of life-history trait plasticity were discussed. PMID:25181493

  3. AN ALTERNATIVE HOST MATRIX BASED ON IRON PHOSPHATE GLASSES FOR THE VITRIFICATION OF SPECIALIZED NUCLEAR WASTE FORMS

    EPA Science Inventory

    Borosilicate glass is the only material currently approved and being used to vitrify high level nuclear waste. Unfortunately, many high level nuclear waste feeds in the U.S. contain components which are chemically incompatible with borosilicate glasses. Current plans call for vit...

  4. Molecular parasitism in the Escherichia coli-Bdellovibrio bacteriovorus system: translocation of the matrix protein from the host to the parasite outer membrane.

    PubMed Central

    Guerrini, F; Romano, V; Valenzi, M; Di Giulio, M; Mupo, M R; Sacco, M

    1982-01-01

    During the intracellular maturation in Escherichia coli of the parasite Bdellovibrio bacteriovorus the outer membrane, major protein I of E. coli (i.e., the matrix protein) becomes associated with the outer membrane of the emerging parasite cells. The binding properties of this protein with the outer membrane of the host and of the parasite are identical. An analogous phenomenon also occurs during Bdellovibrio parasitism on Klebsiella pneumoniae and on Salmonella typhimurium. Possible roles for this scavenging action of Bdellovibrio, and similar phenomena in other parasitic systems, are discussed. Images Fig. 1. Fig. 2. Fig. 3. Fig. 4. Fig. 5. Fig. 6. Fig. 7. PMID:6765198

  5. Decoding Biomass-Sensing Regulons of Clostridium thermocellum Alternative Sigma-I Factors in a Heterologous Bacillus subtilis Host System

    PubMed Central

    Rozman Grinberg, Inna; Garty, Yuval; Bayer, Edward A.; Shoham, Yuval; Lamed, Raphael; Borovok, Ilya

    2016-01-01

    The Gram-positive, anaerobic, cellulolytic, thermophile Clostridium (Ruminiclostridium) thermocellum secretes a multi-enzyme system called the cellulosome to solubilize plant cell wall polysaccharides. During the saccharolytic process, the enzymatic composition of the cellulosome is modulated according to the type of polysaccharide(s) present in the environment. C. thermocellum has a set of eight alternative RNA polymerase sigma (σ) factors that are activated in response to extracellular polysaccharides and share sequence similarity to the Bacillus subtilis σI factor. The aim of the present work was to demonstrate whether individual C. thermocellum σI-like factors regulate specific cellulosomal genes, focusing on C. thermocellum σI6 and σI3 factors. To search for putative σI6- and σI3-dependent promoters, bioinformatic analysis of the upstream regions of the cellulosomal genes was performed. Because of the limited genetic tools available for C. thermocellum, the functionality of the predicted σI6- and σI3-dependent promoters was studied in B. subtilis as a heterologous host. This system enabled observation of the activation of 10 predicted σI6-dependent promoters associated with the C. thermocellum genes: sigI6 (itself, Clo1313_2778), xyn11B (Clo1313_0522), xyn10D (Clo1313_0177), xyn10Z (Clo1313_2635), xyn10Y (Clo1313_1305), cel9V (Clo1313_0349), cseP (Clo1313_2188), sigI1 (Clo1313_2174), cipA (Clo1313_0627), and rsgI5 (Clo1313_0985). Additionally, we observed the activation of 4 predicted σI3-dependent promoters associated with the C. thermocellum genes: sigI3 (itself, Clo1313_1911), pl11 (Clo1313_1983), ce12 (Clo1313_0693) and cipA. Our results suggest possible regulons of σI6 and σI3 in C. thermocellum, as well as the σI6 and σI3 promoter consensus sequences. The proposed -35 and -10 promoter consensus elements of σI6 are CNNAAA and CGAA, respectively. Additionally, a less conserved CGA sequence next to the C in the -35 element and a highly

  6. Decoding Biomass-Sensing Regulons of Clostridium thermocellum Alternative Sigma-I Factors in a Heterologous Bacillus subtilis Host System.

    PubMed

    Muñoz-Gutiérrez, Iván; Ortiz de Ora, Lizett; Rozman Grinberg, Inna; Garty, Yuval; Bayer, Edward A; Shoham, Yuval; Lamed, Raphael; Borovok, Ilya

    2016-01-01

    The Gram-positive, anaerobic, cellulolytic, thermophile Clostridium (Ruminiclostridium) thermocellum secretes a multi-enzyme system called the cellulosome to solubilize plant cell wall polysaccharides. During the saccharolytic process, the enzymatic composition of the cellulosome is modulated according to the type of polysaccharide(s) present in the environment. C. thermocellum has a set of eight alternative RNA polymerase sigma (σ) factors that are activated in response to extracellular polysaccharides and share sequence similarity to the Bacillus subtilis σI factor. The aim of the present work was to demonstrate whether individual C. thermocellum σI-like factors regulate specific cellulosomal genes, focusing on C. thermocellum σI6 and σI3 factors. To search for putative σI6- and σI3-dependent promoters, bioinformatic analysis of the upstream regions of the cellulosomal genes was performed. Because of the limited genetic tools available for C. thermocellum, the functionality of the predicted σI6- and σI3-dependent promoters was studied in B. subtilis as a heterologous host. This system enabled observation of the activation of 10 predicted σI6-dependent promoters associated with the C. thermocellum genes: sigI6 (itself, Clo1313_2778), xyn11B (Clo1313_0522), xyn10D (Clo1313_0177), xyn10Z (Clo1313_2635), xyn10Y (Clo1313_1305), cel9V (Clo1313_0349), cseP (Clo1313_2188), sigI1 (Clo1313_2174), cipA (Clo1313_0627), and rsgI5 (Clo1313_0985). Additionally, we observed the activation of 4 predicted σI3-dependent promoters associated with the C. thermocellum genes: sigI3 (itself, Clo1313_1911), pl11 (Clo1313_1983), ce12 (Clo1313_0693) and cipA. Our results suggest possible regulons of σI6 and σI3 in C. thermocellum, as well as the σI6 and σI3 promoter consensus sequences. The proposed -35 and -10 promoter consensus elements of σI6 are CNNAAA and CGAA, respectively. Additionally, a less conserved CGA sequence next to the C in the -35 element and a highly

  7. An alternative approach for assessment of liquid chromatography-mass spectrometry matrix effects using auto-sampler programmed co-injection.

    PubMed

    Rogers, Caitlyn A; Stockham, Peter C; Nash, Christine M; Martin, Sheridan M; Kostakis, Chris; Lenehan, Claire E

    2016-03-01

    We report the use of auto-sampler programmable functions to co-inject analyte standard solution and matrix extract to assess ion enhancement and suppression (matrix effects) in LC-MS. This is effectively an automated post-extraction addition (APEA) procedure, emulating the manual post-extraction addition (PEA) approach widely adopted for assessment of matrix effects. To verify that APEA was comparable to the conventional PEA approach, matrix effects were determined using both methods for a selection of 31 illicit and pharmaceutical drugs in 10 different human urine extracts. Matrix effects measured using APEA were statistically indistinguishable from manual PEA methodology for 27 of the 31 drugs. Of the four drugs that showed significant differences using the two methods, three differed by less than 2 %, which is within the expected accuracy limits required for matrix effect determinations. The remaining analyte, trimeprazine, was found to degrade in the spiked PEA matrix extract, accounting for the difference between matrix effects measured by the PEA and APEA approaches. APEA enables a single matrix extract to be assessed at multiple analyte concentrations, resulting in a considerable reduction in sample preparation time. In addition, APEA can reduce the quantity of analyte-free sample matrix required for matrix effect assessment, which is an important consideration in certain analytical and bioanalytical fields. This work shows that APEA may be considered as an acceptable alternative to PEA for the assessment of matrix effects in LC-MS method validation and may be applicable to a variety of matrices such as environmental samples. PMID:26781099

  8. Effect of crystallographic phase on green and yellow emissions in Mn-doped zinc silicate nanoparticles incorporated in silica host matrix

    NASA Astrophysics Data System (ADS)

    El Mir, L.; Omri, K.; El Ghoul, J.

    2015-09-01

    Silica host matrix reached by manganese-doped zinc silicate nanoparticles (SiO2/Zn2SiO4:Mn) were in-situ synthesized by a sol-gel process. In our approach, we synthesis ZnO:Mn nanoparticles in supercritical conditions of ethanol. After the incorporation of these nanoparticles in silica host matrix, a heat treatment at 1200 °C and 1500 °C for 2 h was performed for the elaboration of SiO2/Zn2SiO4:Mn nanocomposites. Then, these samples were characterized by various techniques such as X-ray diffraction (XRD), transmission electron microscopy (TEM), scanning electron microscopy (SEM) and photoluminescence (PL). These samples exhibit broad green and yellow PL bands depending on synthesis temperature. The SiO2/Zn2SiO4:Mn prepared at 1200 °C exhibit a green emission centered at about 525 nm while the yellow emission centered at 575 nm resulted from SiO2/Zn2SiO4:Mn prepared at 1500 °C. These two emissions are originated from internal transition in Mn2+ ion doped zinc silicate nanoparticles and the emission wavelength is correlated to the local crystalline field which is fixed by the crystallographic phase.

  9. The effects of host derived metalloproteinases on dentin bond and the role of MMPs inhibitors on dentin matrix degradation

    PubMed Central

    LONGHI, M.; CERRONI, L.; CONDÒ, S.G.; ARIANO, V.; PASQUANTONIO, G.

    2014-01-01

    SUMMARY Objectives. The work has the objective to analyze the literature on the degradation of the adhesive interface. In particular the study is focused on the role of the metalloproteinase in the hydrolytic degradation of collagen matrix in the bonded interface. The survey will concern also the latest innovations to improve and increase the link between dentin and the restorative materials through the MMPs inhibitors. Methods. The research has been carried out in the MEDLINE database by choosing keywords as “metalloproteinases” and “dentin bond” and “degradation”. In vitro studies were included in the research, excluding studies with no human and deciduous teeth. Language was limited to English. Results. The collagenolytic enzymes in mineralized dentin have been demonstrated to have an important role in dental hard tissue pathologies, including the degradation of the hybrid layer. Conclusion. The preservation of the collagen matrix integrity is a key issue in the attempts to improve the dentin bonding durability. PMID:25992261

  10. Variational reduced-density-matrix calculations on radicals: An alternative approach to open-shell ab initio quantum chemistry

    SciTech Connect

    Hammond, Jeff R.; Mazziotti, David A.

    2006-01-15

    An alternative approach to open-shell molecular calculations using the variational two-electron reduced-density-matrix (2-RDM) theory [Mazziotti, Phys. Rev. Lett. 93, 213001 (2004)] is presented. The energy and 2-RDM of the open-shell molecule (or radical) are computed from the limit of dissociating one or more hydrogen atoms from a molecule in a singlet state. Because the ground-state energy of an 'infinitely' separated hydrogen atom in a given finite basis is known, we can determine the energy of the radical by subtracting the energy of one or more hydrogen atoms from the energy of the total dissociated system. The 2-RDM is constrained to have singlet symmetry in all calculations. Two sets of N-representability conditions are employed: (i) two-positivity conditions, and (ii) two-positivity conditions plus the T{sub 2} condition, which is a subset of the three-positivity conditions. Optimization of the energy with respect to the 2-RDM is performed with a first-order algorithm for solving the semidefinite program within the variational 2-RDM method. We present calculations of several radicals near equilibrium as well as the dissociation curves of the diatomic radicals CH and OH.

  11. The mouse matrix metalloproteinase, epilysin (MMP-28), is alternatively spliced and processed by a furin-like proprotein convertase.

    PubMed Central

    Illman, Sara A; Keski-Oja, Jorma; Parks, William C; Lohi, Jouko

    2003-01-01

    Epilysin (MMP-28) is a recently identified member of the matrix metalloproteinase (MMP) family. To explore the expression of epilysin in vivo and to gain insight into its biological functions, we have cloned the mouse epilysin cDNA and determined its expression. The amino acid sequence of the mouse protein is 85% identical with the human sequence and contains conserved features such as an RKKR furin-activation sequence following the prodomain. Unexpectedly, we found two alternatively spliced forms of the epilysin mRNA lacking 30 and 72 nt at the beginning of the seventh exon coding for part of the haemopexin domain. Expression of recombinant epilysin in HT-1080 fibrosarcoma cells indicated that epilysin was secreted as a major 48 kDa form and a minor 58 kDa form. Expression of the 58 kDa form was increased by a synthetic furin inhibitor at the expense of the 48 kDa form, suggesting that furin cleaves and activates epilysin. Epilysin mRNA was detected in a number of mouse tissues, with the highest expression in the lung, placenta, heart and uterus, and lower levels in the testis and gastrointestinal tract. The wide expression of epilysin in intact, healthy tissues suggests that this MMP functions in physiological tissue homoeostasis and turnover. PMID:12803542

  12. Tilted Orientation of Photochromic Dyes with Guest-Host Effect of Liquid Crystalline Polymer Matrix for Electrical UV Sensing

    PubMed Central

    Ranjkesh, Amid; Park, Min-Kyu; Park, Do Hyuk; Park, Ji-Sub; Choi, Jun-Chan; Kim, Sung-Hoon; Kim, Hak-Rin

    2015-01-01

    We propose a highly oriented photochromic dye film for an ultraviolet (UV)-sensing layer, where spirooxazine (SO) derivatives are aligned with the liquid crystalline UV-curable reactive mesogens (RM) using a guest-host effect. For effective electrical UV sensing with a simple metal-insulator-metal structure, our results show that the UV-induced switchable dipole moment amount of the SO derivatives is high; however, their tilting orientation should be controlled. Compared to the dielectric layer with the nearly planar SO dye orientation, the photochromic dielectric layer with the moderately tilted dye orientation shows more than seven times higher the UV-induced capacitance variation. PMID:26729116

  13. Tilted Orientation of Photochromic Dyes with Guest-Host Effect of Liquid Crystalline Polymer Matrix for Electrical UV Sensing.

    PubMed

    Ranjkesh, Amid; Park, Min-Kyu; Park, Do Hyuk; Park, Ji-Sub; Choi, Jun-Chan; Kim, Sung-Hoon; Kim, Hak-Rin

    2015-01-01

    We propose a highly oriented photochromic dye film for an ultraviolet (UV)-sensing layer, where spirooxazine (SO) derivatives are aligned with the liquid crystalline UV-curable reactive mesogens (RM) using a guest-host effect. For effective electrical UV sensing with a simple metal-insulator-metal structure, our results show that the UV-induced switchable dipole moment amount of the SO derivatives is high; however, their tilting orientation should be controlled. Compared to the dielectric layer with the nearly planar SO dye orientation, the photochromic dielectric layer with the moderately tilted dye orientation shows more than seven times higher the UV-induced capacitance variation. PMID:26729116

  14. The role of vesicular stomatitis virus matrix protein in inhibition of host-directed gene expression is genetically separable from its function in virus assembly.

    PubMed Central

    Black, B L; Rhodes, R B; McKenzie, M; Lyles, D S

    1993-01-01

    Recently, the vesicular stomatitis virus matrix (M) protein has been shown to be capable of inhibition of host cell-directed transcription in the absence of other viral components (B. L. Black and D. S. Lyles, J. Virol. 66:4058-4064, 1992). M protein is a major structural protein that is known to play a critical role in virus assembly by binding the helical ribonucleoprotein core of the virus to the cytoplasmic surface of the cell plasma membrane during budding. In this study, two M protein mutants were tested to determine whether the inhibition of host transcription by M protein is an indirect effect of its function in virus assembly or whether it represents an independent function of M protein. The mutant M protein of the conditionally temperature-sensitive (ts) vesicular stomatitis virus mutant, tsO82, was found to be defective in its ability to inhibit host-directed gene expression, as shown by its inability to inhibit expression of a cotransfected target gene encoding chloramphenicol acetyltransferase. The ability of the tsO82 M protein to function in virus assembly was similar to that of wild-type M protein, as shown by its ability to complement the group III ts M protein mutant, tsO23. Another mutant, MN1, which lacks amino acids 4 to 21 of M protein demonstrated that the abilities of M protein to inhibit chloramphenicol acetyltransferase gene expression and to localize to the nucleus were unaffected by deletion of this lysine-rich amino-terminal region but that the ability to function in virus assembly was ablated. Thus, the two M protein mutants examined in this study exhibited complementary phenotypes: tsO82 M protein functioned in virus assembly but was defective in inhibition of host-directed gene expression, while MN1 M protein functioned in inhibiting gene expression but was unable to function in virus assembly. These data demonstrate that the role of M protein in inhibition of host transcription can be separated genetically from its role in virus

  15. Influence of the packing fraction and host matrix on the magnetoelastic anisotropy in Ni nanowire composite arrays

    NASA Astrophysics Data System (ADS)

    Piraux, Luc; Hamoir, Gaël; Encinas, Armando; De La Torre Medina, Joaquin; Abreu Araujo, Flavio

    2013-09-01

    The influence of the packing fraction on thermally induced magnetoelastic effects has been studied in Ni nanowires embedded in polycarbonate, poly(vinylidene difluoride), and alumina nanoporous membranes of different porosities for temperatures between 77 K and 345 K. For nanowires embedded in polymer membranes, the contrasting shift in the ferromagnetic resonance frequency when the temperature is either above or below ambient temperature is consistent with the occurrence of uniaxial magnetoelastic anisotropy effects due to the large thermal expansion coefficient mismatch between the metal nanowires and the membrane. A model which considers the influence of the nanowires packing fraction and the membrane material on the magnetoelastic effects, arising from the matrix-assisted deformation process, is proposed. The model is able to successfully explain the experimentally observed effects for the Ni nanowire arrays embedded in the different porous membranes and their variation with the packing fraction. The possibility to modulate the magnetic anisotropy of such nanocomposites by an appropriate choice of membrane material, packing fraction, and sample temperature is of considerable importance to achieve magnetically tunable devices.

  16. A Sheet-like Carbon Matrix Hosted Sulfur as Cathode for High-performance Lithium-Sulfur Batteries

    PubMed Central

    Lu, Songtao; Chen, Yan; Zhou, Jia; Wang, Zhida; Wu, Xiaohong; Gu, Jian; Zhang, Xiaoping; Pang, Aimin; Jiao, Zilong; Jiang, Lixiang

    2016-01-01

    Lithium-sulfur (Li-S) batteries are a promising candidate of next generation energy storage systems owing to its high theoretical capacity and energy density. However, to date, its commercial application was hindered by the inherent problems of sulfur cathode. Additionally, with the rapid decline of non-renewable resources and active appeal of green chemistry, the intensive research of new electrode materials was conducted worldwide. We have obtained a sheet-like carbon material (shaddock peel carbon sheets SPCS) from organic waste shaddock peel, which can be used as the conductive carbon matrix for sulfur-based cathodes. Furthermore, the raw materials are low-cost, truly green and recyclable. As a result, the sulfur cathode made with SPCS (SPCS-S), can deliver a high reversible capacity of 722.5 mAh g−1 at 0.2 C after 100 cycles with capacity recuperability of ~90%, demonstrating that the SPCS-S hybrid is of great potential as the cathode for rechargeable Li-S batteries. The high electrochemical performance of SPCS-S hybrid could be attributed to the sheet-like carbon network with large surface area and high conductivity of the SPCS, in which the carbon sheets enable the uniform distribution of sulfur, better ability to trap the soluble polysulfides and accommodate volume expansion/shrinkage of sulfur during repeated charge/discharge cycles. PMID:26842015

  17. A Sheet-like Carbon Matrix Hosted Sulfur as Cathode for High-performance Lithium-Sulfur Batteries

    NASA Astrophysics Data System (ADS)

    Lu, Songtao; Chen, Yan; Zhou, Jia; Wang, Zhida; Wu, Xiaohong; Gu, Jian; Zhang, Xiaoping; Pang, Aimin; Jiao, Zilong; Jiang, Lixiang

    2016-02-01

    Lithium-sulfur (Li-S) batteries are a promising candidate of next generation energy storage systems owing to its high theoretical capacity and energy density. However, to date, its commercial application was hindered by the inherent problems of sulfur cathode. Additionally, with the rapid decline of non-renewable resources and active appeal of green chemistry, the intensive research of new electrode materials was conducted worldwide. We have obtained a sheet-like carbon material (shaddock peel carbon sheets SPCS) from organic waste shaddock peel, which can be used as the conductive carbon matrix for sulfur-based cathodes. Furthermore, the raw materials are low-cost, truly green and recyclable. As a result, the sulfur cathode made with SPCS (SPCS-S), can deliver a high reversible capacity of 722.5 mAh g-1 at 0.2 C after 100 cycles with capacity recuperability of ~90%, demonstrating that the SPCS-S hybrid is of great potential as the cathode for rechargeable Li-S batteries. The high electrochemical performance of SPCS-S hybrid could be attributed to the sheet-like carbon network with large surface area and high conductivity of the SPCS, in which the carbon sheets enable the uniform distribution of sulfur, better ability to trap the soluble polysulfides and accommodate volume expansion/shrinkage of sulfur during repeated charge/discharge cycles.

  18. A Sheet-like Carbon Matrix Hosted Sulfur as Cathode for High-performance Lithium-Sulfur Batteries.

    PubMed

    Lu, Songtao; Chen, Yan; Zhou, Jia; Wang, Zhida; Wu, Xiaohong; Gu, Jian; Zhang, Xiaoping; Pang, Aimin; Jiao, Zilong; Jiang, Lixiang

    2016-01-01

    Lithium-sulfur (Li-S) batteries are a promising candidate of next generation energy storage systems owing to its high theoretical capacity and energy density. However, to date, its commercial application was hindered by the inherent problems of sulfur cathode. Additionally, with the rapid decline of non-renewable resources and active appeal of green chemistry, the intensive research of new electrode materials was conducted worldwide. We have obtained a sheet-like carbon material (shaddock peel carbon sheets SPCS) from organic waste shaddock peel, which can be used as the conductive carbon matrix for sulfur-based cathodes. Furthermore, the raw materials are low-cost, truly green and recyclable. As a result, the sulfur cathode made with SPCS (SPCS-S), can deliver a high reversible capacity of 722.5 mAh g(-1) at 0.2 C after 100 cycles with capacity recuperability of ~90%, demonstrating that the SPCS-S hybrid is of great potential as the cathode for rechargeable Li-S batteries. The high electrochemical performance of SPCS-S hybrid could be attributed to the sheet-like carbon network with large surface area and high conductivity of the SPCS, in which the carbon sheets enable the uniform distribution of sulfur, better ability to trap the soluble polysulfides and accommodate volume expansion/shrinkage of sulfur during repeated charge/discharge cycles. PMID:26842015

  19. Characterization of an Sf-rhabdovirus-negative Spodoptera frugiperda cell line as an alternative host for recombinant protein production in the baculovirus-insect cell system.

    PubMed

    Maghodia, Ajay B; Geisler, Christoph; Jarvis, Donald L

    2016-06-01

    Cell lines derived from the fall armyworm, Spodoptera frugiperda (Sf), are widely used as hosts for recombinant protein production in the baculovirus-insect cell system (BICS). However, it was recently discovered that these cell lines are contaminated with a virus, now known as Sf-rhabdovirus [1]. The detection of this adventitious agent raised a potential safety issue that could adversely impact the BICS as a commercial recombinant protein production platform. Thus, we examined the properties of Sf-RVN, an Sf-rhabdovirus-negative Sf cell line, as a potential alternative host. Nested RT-PCR assays showed Sf-RVN cells had no detectable Sf-rhabdovirus over the course of 60 passages in continuous culture. The general properties of Sf-RVN cells, including their average growth rates, diameters, morphologies, and viabilities after baculovirus infection, were virtually identical to those of Sf9 cells. Baculovirus-infected Sf-RVN and Sf9 cells produced equivalent levels of three recombinant proteins, including an intracellular prokaryotic protein and two secreted eukaryotic glycoproteins, and provided similar N-glycosylation patterns. In fact, except for the absence of Sf-rhabdovirus, the only difference between Sf-RVN and Sf9 cells was SF-RVN produced higher levels of infectious baculovirus progeny. These results show Sf-RVN cells can be used as improved, alternative hosts to circumvent the potential safety hazard associated with the use of Sf-rhabdovirus-contaminated Sf cells for recombinant protein manufacturing with the BICS. PMID:26923062

  20. A Large-panel Two-CCD Camera Coordinate System with an Alternate-Eight-Matrix Look-Up-Table Method

    NASA Astrophysics Data System (ADS)

    Lin, Chern-Sheng; Lu, An-Tsung; Hsu, Yuen-Chang; Tien, Chuen-Lin; Chen, Der-Chin; Chang, Nin-Chun

    2012-03-01

    This study proposed a novel positioning model, composing of a two-camera calibration system and an Alternate-Eight-Matrix (AEM) Look-Up-Table (LUT). Two video cameras were fixed on two sides of a large-size screen to solve the problem of field of view. The first to the fourth LUTs were used to compute the corresponding positions of specified regions on the screen captured by the camera on the right side. In these four LUTs, the coordinate mapping data of the target were stored in two matrixes, while the gray level threshold values of different positions were stored in other matrixes. Similarly, the fifth to the eighth LUTs were used to compute the corresponding positions of the specified regions on the screen captured by the camera on the left side. Experimental results showed that the proposed model can solve the problems of dead zones and non-uniform light fields, while achieving rapid and precise positioning results.

  1. Transmission of Citrus leprosis virus C by Brevipalpus phoenicis (Geijskes) to Alternative Host Plants Found in Citrus Orchards

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The equivalent of US$ 75 million is spent each year in Brazil to control Brevipalpus phoenicis, a mite vector of Citrus leprosis virus C (CiLV-C). In this study we investigated the possibility that hedgerows, windbreaks, and weeds normally found in citrus orchards could host CiLV-C. Mites reared on ...

  2. Microbial community analysis and identification of alternative host-specific fecal indicators in fecal and river water samples using pyrosequencing.

    PubMed

    Jeong, Ju-Yong; Park, Hee-Deung; Lee, Kyong-Hee; Weon, Hang-Yeon; Ka, Jong-Ok

    2011-08-01

    It is important to know the comprehensive microbial communities of fecal pollution sources and receiving water bodies for microbial source tracking. Pyrosequencing targeting the V1-V3 hypervariable regions of the 16S rRNA gene was used to investigate the characteristics of bacterial and Bacteroidales communities in major fecal sources and river waters. Diversity analysis indicated that cow feces had the highest diversities in the bacterial and Bacteroidales group followed by the pig sample, with human feces having the lowest value. The Bacteroidales, one of the potential fecal indicators, totally dominated in the fecal samples accounting for 31%-52% of bacterial sequences, but much less (0.6%) in the river water. Clustering and Venn diagram analyses showed that the human sample had a greater similarity to the pig sample in the bacterial and Bacteroidales communities than to samples from other hosts. Traditional fecal indicators, i.e., Escherichia coli, were detected in the human and river water samples at very low rates and Clostridium perfringens and enterococci were not detected in any samples. Besides the Bacteroidales group, some microorganisms detected in the specific hosts, i.e., Parasutterella excrementihominis, Veillonella sp., Dialister invisus, Megamonas funiformis, and Ruminococcus lactaris for the human and Lactobacillus amylovorus and Atopostipes sp. for the pig, could be used as potential host-specific fecal indicators. These microorganisms could be used as multiple fecal indicators that are not dependent on the absence or presence of a single indicator. Monitoring for multiple indicators that are highly abundant and host-specific would greatly enhance the effectiveness of fecal pollution source tracking. PMID:21887641

  3. Preliminary study on calcium aluminosilicate glass as a potential host matrix for radioactive 90Sr--an approach based on natural analogue study.

    PubMed

    Sengupta, Pranesh; Fanara, Sara; Chakraborty, Sumit

    2011-06-15

    Given the environmental-, safety- and security risks associated with sealed radioactive sources it is important to identify suitable host matrices for (90)Sr that is used for various peaceful applications. As SrO promotes phase separation within borosilicate melt, aluminosilicate bulk compositions belonging to anorthite-wollastonite-gehlenite stability field are studied in this work. Tests for their homogeneity, microstructural characteristics and resistance to phase separation narrowed the choice down to the composition CAS11 (CaO=35 wt%, Al(2)O(3)=20 wt%, SiO(2)=45 wt%). We find that up to 30 wt% SrO can be loaded in this glass without phase separation (into Ca, Sr-rich and Sr-poor, Si-rich domains). Leaching behaviour of the glasses differs depending on the content and distribution of Sr. In general, the elemental leach rates determined from conventional PCT experimental procedure yield values better than 10(-7)gcm(-2)day(-1) for both CAS11 base glass as well as SrO doped glass. It was noted that leach rates calculated on the basis of Ca(2+) and Sr(2+) were of the same order and bit higher compared to those calculated on the basis of Si(4+) and Al(3+). During accelerated leaching tests, zeolite and zeolite+epidote were found to have developed on CAS11 base glass and SrO doped glasses respectively. The Sr bulk diffusion coefficients is found to vary from ∼ 10(-15) to 10(-13)cm(2)/s at temperature intervals as high as 725-850°C. Based on the experimental observations, it is suggested that CAS11 glass can be used as host matrix of (90)Sr for various applications of radioactive Sr-pencils. PMID:21477923

  4. Organ heterogeneity of host-derived matrix metalloproteinase expression and its involvement in multiple-organ metastasis by lung cancer cell lines.

    PubMed

    Shiraga, Minoru; Yano, Seiji; Yamamoto, Akihiko; Ogawa, Hirohisa; Goto, Hisatsugu; Miki, Toyokazu; Miki, Keisuke; Zhang, Helong; Sone, Saburo

    2002-10-15

    Cancer metastasis is tightly regulated by the interaction of tumor cells and host organ microenvironments. Matrix metalloproteinases (MMPs), produced by both tumor cells and host stromal cells, play a central role in tumor invasion and angiogenesis. We determined whether metastatic potential of lung cancer to multiple organs is dependent solely on the expression of MMPs by tumor cells, using two metastasis models of human lung cancer cell lines expressing various levels of MMPs and a MMP inhibitor (ONO-4817). In the lung metastasis model, tumor cells (PC14, PC14PE6, H226, A549) inoculated i.v. into nude or SCID mice metastasized only in the lung. In the multiple-organ metastasis model, tumor cells (RERF-LC-AI, SBC-3/DOX, H69/VP, which express low levels of MMPs) inoculated i.v. into natural killer cell-depleted SCID mice metastasized into the liver, kidneys, and systemic lymph nodes. Film in situ zymography analysis revealed that the nontumor parenchyma of the lung had no gelatinolytic activity, whereas gelatinolytic activity of the liver and kidney was high and low, respectively. In the lung metastasis model, gelatinolytic activity of lung nodules directly correlated with the in vitro expression of MMP-2 and MMP-9 by tumor cells. Inhibition of MMP activity by ONO-4817 suppressed lung metastasis by the cell lines that expressed MMPs, but not those that did not express MMP, via the inhibition of MMP activity of lung tumors. In the multiple-organ metastasis model, liver parenchyma, but not liver nodules, showed gelatinolytic activity. The MMP inhibition reduced metastasis to the liver, but not to the kidney or lymph nodes, via inhibition of MMP activity of liver parenchyma. These findings suggest that MMP expression varies among the host organ microenvironments and that stromal MMPs may promote metastasis of lung cancer. Therefore, antimetastatic effects based on MMP inhibition may be dependent on MMPs derived not only from tumor cells but also from organ

  5. Isolation of yeast artificial chromosomes free of endogenous yeast chromosomes: construction of alternate hosts with defined karyotypic alterations.

    PubMed Central

    Hamer, L; Johnston, M; Green, E D

    1995-01-01

    An intrinsic feature of yeast artificial chromosomes (YACs) is that the cloned DNA is generally in the same size range (i.e., approximately 200-2000 kb) as the endogenous yeast chromosomes. As a result, the isolation of YAC DNA, which typically involves separation by pulsed-field gel electrophoresis, is frequently confounded by the presence of a comigrating or closely migrating endogenous yeast chromosome(s). We have developed a strategy that reliably allows the isolation of any YAC free of endogenous yeast chromosomes. Using recombination-mediated chromosome fragmentation, a set of Saccharomyces cerevisiae host strains was systematically constructed. Each strain contains defined alterations in its electrophoretic karyotype, which provide a large-size interval devoid of endogenous chromosomes (i.e., a karyotypic "window"). All of the constructed strains contain the kar1-delta 15 mutation, thereby allowing the efficient transfer of a YAC from its original host into an appropriately selected window strain using the kar1-transfer procedure. This approach provides a robust and efficient means to obtain relatively pure YAC DNA regardless of YAC size. Images Fig. 1 Fig. 2 Fig. 3 Fig. 4 PMID:8524833

  6. Carbon isotope ratios document that the elytra of western corn rootworm (Coleoptera: Chrysomelidae) reflects adult versus larval feeding and later instar larvae prefer Bt corn to alternate hosts.

    PubMed

    Hiltpold, Ivan; Adamczyk, John J; Higdon, Matthew L; Clark, Thomas L; Ellersieck, Mark R; Hibbard, Bruce E

    2014-06-01

    In much of the Corn Belt and parts of Europe, the western corn rootworm, Diabrotica virgifera virgifera LeConte, is the most important insect pest of maize. The need for additional basic knowledge of this pest has been highlighted while developing resistance management plans for insecticidal genetically modified crops. This study evaluated the possibility of tracking feeding habits of western corn rootworm larvae using stable carbon isotope signatures. Plants accumulate different ratios of (13)C:(12)C isotopes, usually expressed as δ(13)C, according to whether they use the C3 or C4 photosynthetic pathway. Herbivore biomass is expected to reflect the δ(13)C of the food they eat. For the current experiment, western corn rootworm larvae were grown on different species of plants exhibiting different δ(13)C values. The δ(13)C values were then measured in elytra of emerged beetles. When beetles were unfed, biomass reflected larval feeding. When beetles were fed for 31 d postemergence, δ(13)C values of elytra almost exclusively reflected adult feeding. These results suggest the use of caution in the interpretation of δ(13)C data aiming to document larval diet history when adult feeding history is unknown. The technique was also used to evaluate western corn rootworm larval choice between alternate hosts and maize with and without genetically modified (Bt) traits aimed at their control. Propensity for feeding on alternate hosts versus maize was biased toward feeding on maize regardless whether the maize had Bt or not, suggesting western corn rootworm larvae were not repelled by Bt. These data will be helpful for regulators in interpreting western corn rootworm feeding data on Bt maize. PMID:24874160

  7. Global Repression of Host-Associated Genes of the Lyme Disease Spirochete through Post-Transcriptional Modulation of the Alternative Sigma Factor RpoS

    PubMed Central

    Dulebohn, Daniel P.; Hayes, Beth M.; Rosa, Patricia A.

    2014-01-01

    Borrelia burgdorferi, the agent of Lyme disease, is a vector-borne pathogen that transits between Ixodes ticks and vertebrate hosts. During the natural infectious cycle, spirochetes must globally adjust their transcriptome to survive in these dissimilar environments. One way B. burgdorferi accomplishes this is through the use of alternative sigma factors to direct transcription of specific genes. RpoS, one of only three sigma factors in B. burgdorferi, controls expression of genes required during tick-transmission and infection of the mammalian host. How spirochetes switch between different sigma factors during the infectious cycle has remained elusive. Here we establish a role for a novel protein, BBD18, in the regulation of the virulence-associated sigma factor RpoS. Constitutive expression of BBD18 repressed transcription of RpoS-dependent genes to levels equivalent to those observed in an rpoS mutant. Consistent with the global loss of RpoS-dependent transcripts, we were unable to detect RpoS protein. However, constitutive expression of BBD18 did not diminish the amount of rpoS transcript, indicating post-transcriptional regulation of RpoS by BBD18. Interestingly, BBD18-mediated repression of RpoS is independent of both the rpoS promoter and the 5’ untranslated region, suggesting a mechanism of protein destabilization rather than translational control. We propose that BBD18 is a novel regulator of RpoS and its activity likely represents a first step in the transition from an RpoS-ON to an RpoS-OFF state, when spirochetes transition from the host to the tick vector. PMID:24671196

  8. Mitochondrial alternative oxidase is involved in both compatible and incompatible host-virus combinations in Nicotiana benthamiana.

    PubMed

    Zhu, Feng; Deng, Xing-Guang; Xu, Fei; Jian, Wei; Peng, Xing-Ji; Zhu, Tong; Xi, De-Hui; Lin, Hong-Hui

    2015-10-01

    The alternative oxidase (AOX) functions in the resistance to biotic stress. However, the mechanisms of AOX in the systemic antiviral defense response and N (a typical resistance gene)-mediated resistance to Tobacco mosaic virus (TMV) are elusive. A chemical approach was undertaken to investigate the role of NbAOX in the systemic resistance to RNA viruses. Furthermore, we used a virus-induced gene-silencing (VIGS)-based genetics approach to investigate the function of AOX in the N-mediated resistance to TMV. The inoculation of virus significantly increased the NbAOX transcript and protein levels and the cyanide-resistant respiration in the upper un-inoculated leaves. Pretreatment with potassium cyanide greatly increased the plant's systemic resistance, whereas the application of salicylhydroxamic acid significantly compromised the plant's systemic resistance. Additionally, in NbAOX1a-silenced N-transgenic Nicotiana benthamiana plants, the inoculated leaf collapsed and the movement of TMV into the systemic tissue eventually led to the spreading of HR-PCD and the death of the whole plant. The hypersensitive response marker gene HIN1 was significantly increased in the NbAOX1a-silenced plants. Significant amounts of TMV-CP mRNA and protein were detected in the NbAOX1a-silenced plants but not in the control plants. Overall, evidence is provided that AOX plays important roles in both compatible and incompatible plant-virus combinations. PMID:26398788

  9. Quantum confinement effect in multilayer structure of alternate CdSe and SiOx insulator matrix thinfilms

    NASA Astrophysics Data System (ADS)

    Melvin David Kumar, M.; Devadason, Suganthi

    2013-06-01

    Multilayer (ML) structure of layer-by-layer deposited CdSe/SiOx thin films and their monolayers were prepared using sequential thermal evaporation technique. X-ray diffraction study confirmed the (002) plane of CdSe with wurtzite structure. It is noticed that the microstrain, developed in ML thin films, increased with decreasing particle size. Experimentally measured band gap energies confirmed the splitting of valence band energy levels which rise due to hole confinement in CdSe. Crystallite sizes (5-7 nm) were calculated using the effective mass approximation model (i.e., Brus model) which shows that the diameter of crystallites was smaller than the Bohr exciton diameter (11.2 nm) of CdSe. The main band in the emission spectra of ML samples gradually shifted to longer wavelength side when particle size was increased from 5 to 7 nm. This is characteristic of quantum size effect. It is inferred that disorderliness in CdSe/SiOx ML thin films would increase when the thickness of CdSe sublayer is greater than that of SiOx matrix layer.

  10. [Simultaneous resolution and determination of tyrosine, tryptophan and phenylalanine by alternating penalty trilinear decomposition algorithm coupled with 3D emission-excitation matrix fluorometry].

    PubMed

    Xiao, Jin; Ren, Feng-lian; Song, Ge; Liao, Lü; Yu, Wen-feng; Zeng, Tao

    2007-10-01

    A new method using alternating penalty trilinear decomposition algorithm coupled with excitation-emission matrix fluorometry has been developed for simultaneous resolution and determination of tyrosine, phenylalanine and tryptophan. Their correlation coefficients were 0.9987, 0.9995 and 0.9993 respectively. The contents of tyrosine, phenylalanine and tryptophan in Hibiscus syriacus L. leaves were also be determined by this method after being extracted by ultrasonic. The coefficients of variation and the recoveries of the three amino acids were 0.84%, 0.36%, 1.59% and 101.0%-92.7%, 106.5%-93.0%, 103.0%-95.0% respectively. All these show that this is a simple, fast and cridible method. PMID:18306802

  11. A Novel and Alternative Treatment Method for Diabetic Heel Ulceration Exposing the Calcaneus Which Is Not Suitable for Flap Surgery: Vacuum Assisted Sandwich Dermal Matrix

    PubMed Central

    Bingol, Ugur A.; Cinar, Can; Arslan, Hakan; Altındas, Muzaffer

    2015-01-01

    Background. Currently, free flaps and pedicled flaps are the first treatment choices for large heel ulcer reconstruction. However, flap reconstruction of heel ulcerations cannot be performed in all diabetics especially with concurrent severe peripheral vascular disease because of higher flap failure rate. In recent years, the use of acellular dermal matrix (ADM) has emerged as an alternative treatment option for extremity ulcers. Methods. We present 13 diabetic patients with a large heel ulceration exposing the calcaneus, who were not eligible for flap surgery due to the presence of only one patent artery of trifurcation. These cases were treated with the vacuum assisted sandwich dermal matrix (VASDEM) method. Results. None of the patients required amputation. Skin grafting was successful in ten patients. Although partial losses were observed in three patients, they were healed spontaneously without surgical interventions. During the follow-up period none of the patients developed ulceration on the treatment area. All patients maintained their preoperative ambulatory ability. Conclusion. VASDEM is a novel method offering opportunity for treatment before proceeding to amputation in diabetic heel ulceration exposing the calcaneus which is not suitable for flap surgery. It also has the potential to close wounds of all sizes independent of the vessel status and wound size in selected diabetic patients. PMID:26516626

  12. Matrix-free analysis of selected benzodiazepines in human serum samples using alternating trilinear decomposition modeling of fast liquid chromatography diode array detection data.

    PubMed

    Vosough, Maryam; Iravani, Negar J

    2016-02-01

    This paper describes the development and validation of a simple and efficient bioanalytical procedure for simultaneous determination of alprazolam, clonazepam, diazepam in human serum samples using high performance liquid chromatography with photodiode-array detection, regarding a fast elution methodology in 4 min. Briefly, this method consists of a simple liquid extraction step of serum samples followed by HPLC analysis on a C18 column. After confirming the absence of matrix effect, an external standard methodology has been applied for quantification purposes. Due to the presence of serum endogenous components as uncalibrated components in the sample, the second-order calibration based on alternating trilinear decomposition has been applied on a set of absorbance matrices collected as a function of retention time and wavelengths. Acceptable resolution and quantification results were achieved in the presence of matrix interferences and the second-order advantage was fully exploited. The average recoveries for alprazolam, clonazepam and diazepam were 89.1%, 96.3% and 94.7% and relative standard deviation values for intra- and inter-day precision were equal or lower than 8.1% and 9.4%, respectively. The developed method enabled us to determine the analytes in the various serum samples in the presence of overlapped profiles, while keeping experimental time and extraction step at the minimum. PMID:26653472

  13. Degradation of extracellular matrix by larvae of Schistosoma mansoni. I. Degradation by cercariae as a model for initial parasite invasion of host

    SciTech Connect

    McKerrow, J.H.; Keene, W.E.; Jeong, K.H.; Werb, Z.

    1983-01-01

    The ability of cercariae of Schistosoma mansoni to degrade a model extracellular connective tissue matrix produced by rat vascular smooth muscle cells in culture was investigated. In this model, connective tissue macromolecules are present in the interactive framework that characterizes their structure in vivo. Cercariae were stimulated to degrade the matrix by skin lipid or linoleic acid. At the maximally stimulating concentration of linoleic acid (25 ..mu..g/cm/sup 2/), 68% of the total matrix was degraded, including 57% of the glycoprotein, 79% of the elastin, and 8% of the collagen. Degradation of matrix was inhibited by ..cap alpha../sub 1/-proteinase inhibitor and soybean trypsin inhibitor. Ethylenediaminetetraacetic acid inhibited degradation by unstimulated but not linoleic acid-stimulated cercariae. Preacetabular gland secretions collected from cercariae also degraded the matrix with an activity 86% of that of live cercariae. Preacetabular gland proteolytic activity was also inhibited by ..cap alpha../sub 1/-proteinase inhibitor, soybean trypsin inhibitor, and ethylenediaminetetraacetic acid. The similar characteristics of matrix degradation by both live cercariae and cercarial preacetabular gland secretions support the idea that a proteinase secreted from cercarial preacetabular glands facilitates invasion of skin and connective tissue by these larvae. Degradation of elastin and glycoprotein constituentes of extracellular matrix is probably essential for skin penetration.

  14. Sn-loss effect in a Sn-implanted a-SiO2 host-matrix after thermal annealing: A combined XPS, PL, and DFT study

    NASA Astrophysics Data System (ADS)

    Zatsepin, D. A.; Zatsepin, A. F.; Boukhvalov, D. W.; Kurmaev, E. Z.; Gavrilov, N. V.

    2016-03-01

    Amorphous a-SiO2 host-matrices were implanted with Sn-ions with and without posterior thermal tempering at 900 °C for 1 h in ambient air. X-ray photoelectron spectroscopy analysis (XPS core-levels, XPS valence band mapping), photoluminescence (PL) probing, and density functional calculations (DFT) were employed to enable a detailed electronic structure characterization of these samples. It was experimentally established that the process of Sn-embedding into the a-SiO2 host occurs following two dissimilar trends: the Sn4+ → Si4+ substitution in a-SiO2:Sn (without tempering), and Sn-metal clustering as interstitials in a-SiO2:Sn (900 °C, 1 h). Both trends were modeled using calculated formation energies and partial densities of states (PDOS) as well as valence band (VB) simulations, which yielded evidence that substitutional defect generation occurs with the help of ion-implantation stimulated translocation of the host-atoms from their stoichiometric positions to the interstitial void. Experimental and theoretical data obtained coincide in terms of the reported Sn-loss effect in a-SiO2:Sn (900 °C, 1 h) due to thermally-induced electronic host-structure re-arraignment, which manifests as backward host-atoms translocation into stoichiometric positions and the posterior formation of Sn-metal clusters.

  15. Matrix-Assisted Laser Desorption Ionization–Time of Flight Mass Spectrometry as an Alternative to 16S rRNA Gene Sequencing for Identification of Difficult-To-Identify Bacterial Strains▿†

    PubMed Central

    Bizzini, A.; Jaton, K.; Romo, D.; Bille, J.; Prod'hom, G.; Greub, G.

    2011-01-01

    Conventional methods are sometimes insufficient to identify human bacterial pathogens, and alternative techniques, often molecular, are required. Matrix-assisted laser desorption ionization–time of flight mass spectrometry (MALDI-TOF MS) identified with a valid score 45.9% of 410 clinical isolates from 207 different difficult-to-identify species having required 16S rRNA gene sequencing. MALDI-TOF MS might represent an alternative to 16S rRNA gene sequencing. PMID:21106794

  16. Quantification of strontium in human serum by ICP-MS using alternate analyte-free matrix and its application to a pilot bioequivalence study of two strontium ranelate oral formulations in healthy Chinese subjects.

    PubMed

    Zhang, Dan; Wang, Xiaolin; Liu, Man; Zhang, Lina; Deng, Ming; Liu, Huichen

    2015-01-01

    A rapid, sensitive and accurate ICP-MS method using alternate analyte-free matrix for calibration standards preparation and a rapid direct dilution procedure for sample preparation was developed and validated for the quantification of exogenous strontium (Sr) from the drug in human serum. Serum was prepared by direct dilution (1:29, v/v) in an acidic solution consisting of nitric acid (0.1%) and germanium (Ge) added as internal standard (IS), to obtain simple and high-throughput preparation procedure with minimized matrix effect, and good repeatability. ICP-MS analysis was performed using collision cell technology (CCT) mode. Alternate matrix method by using distilled water as an alternate analyte-free matrix for the preparation of calibration standards (CS) was used to avoid the influence of endogenous Sr in serum on the quantification. The method was validated in terms of selectivity, carry-over, matrix effects, lower limit of quantification (LLOQ), linearity, precision and accuracy, and stability. Instrumental linearity was verified in the range of 1.00-500ng/mL, corresponding to a concentration range of 0.0300-15.0μg/mL in 50μL sample of serum matrix and alternate matrix. Intra- and inter-day precision as relative standard deviation (RSD) were less than 8.0% and accuracy as relative error (RE) was within ±3.0%. The method allowed a high sample throughput, and was sensitive and accurate enough for a pilot bioequivalence study in healthy male Chinese subjects following single oral administration of two strontium ranelate formulations containing 2g strontium ranelate. PMID:25023847

  17. Use of collagen gel as an alternative extracellular matrix for the in vitro and in vivo growth of murine small intestinal epithelium.

    PubMed

    Jabaji, Ziyad; Sears, Connie M; Brinkley, Garrett J; Lei, Nan Ye; Joshi, Vaidehi S; Wang, Jiafang; Lewis, Michael; Stelzner, Matthias; Martín, Martín G; Dunn, James C Y

    2013-12-01

    Methods for the in vitro culture of primary small intestinal epithelium have improved greatly in recent years. A critical barrier for the translation of this methodology to the patient's bedside is the ability to grow intestinal stem cells using a well-defined extracellular matrix. Current methods rely on the use of Matrigel(™), a proprietary basement membrane-enriched extracellular matrix gel produced in mice that is not approved for clinical use. We demonstrate for the first time the capacity to support the long-term in vitro growth of murine intestinal epithelium in monoculture, using type I collagen. We further demonstrate successful in vivo engraftment of enteroids co-cultured with intestinal subepithelial myofibroblasts in collagen gel. Small intestinal crypts were isolated from 6 to 10 week old transgenic enhanced green fluorescent protein (eGFP+) mice and suspended within either Matrigel or collagen gel; cultures were supported using previously reported media and growth factors. After 1 week, cultures were either lysed for DNA or RNA extraction or were implanted subcutaneously in syngeneic host mice. Quantitative real-time polymerase chain reaction (qPCR) was performed to determine expansion of the transgenic eGFP-DNA and to determine the mRNA gene expression profile. Immunohistochemistry was performed on in vitro cultures and recovered in vivo explants. Small intestinal crypts reliably expanded to form enteroids in either Matrigel or collagen in both mono- and co-cultures as confirmed by microscopy and eGFP-DNA qPCR quantification. Collagen-based cultures yielded a distinct morphology with smooth enteroids and epithelial monolayer growth at the gel surface; both enteroid and monolayer cells demonstrated reactivity to Cdx2, E-cadherin, CD10, Periodic Acid-Schiff, and lysozyme. Collagen-based enteroids were successfully subcultured in vitro, whereas pure monolayer epithelial sheets did not survive passaging. Reverse transcriptase-polymerase chain reaction

  18. Dried blood spot on-card derivatization: an alternative form of sample handling to overcome the instability of thiorphan in biological matrix.

    PubMed

    Mess, Jean-Nicholas; Taillon, Marie-Pierre; Côté, Cynthia; Garofolo, Fabio

    2012-12-01

    Thiorphan, the active metabolite of racecadotril, can undergo oxidation in biological matrices such as blood and plasma. In bioanalysis, a general approach for the stabilization of such a molecule is to derivatize the thiol group to a more stable thioether, often requiring complex handling procedures at the clinical site. In this research, the concept of dried blood spot (DBS) on-card derivatization was evaluated to stabilize thiorphan. DBS cards were in-house pre-treated with 2-bromo-3'-methoxyacetophenone and left to dry prior to blood spotting. Thiorphan was shown to be effectively derivatized to thiorphan-methoxyacetophenone once applied on the in-house pre-treated cards. Thiorphan-methoxyacetophenone was extracted by soaking a 6 mm DBS punch in methanol containing the internal standard (thiorphan-methoxyacetophenone-D₅). Chromatographic separation was achieved on a Waters XBridge C₁₈ column with a gradient elution of 5 mM NH₄HCO₃ and methanol in 2.5 min and detection by ESI(+)/MS/MS. A linear (weighted 1/x²) relationship was obtained over a concentration range of 5.00-600.00 ng/mL. The assay met regulatory guidelines acceptance criteria for sensitivity, selectivity, precision and accuracy, matrix effect, recovery, dilution integrity and multiple stability evaluations. The DBS on-card derivatization has shown to be an easy and reliable alternative form of sample collection for the quantification of thiorphan. PMID:22511292

  19. miRNA-based buffering of the cobblestone–lissencephaly-associated extracellular matrix receptor dystroglycan via its alternative 3′-UTR

    PubMed Central

    Yatsenko, Andriy S.; Marrone, April K.; Shcherbata, Halyna R.

    2014-01-01

    Many proteins are expressed dynamically during different stages of cellular life and the accuracy of protein amounts is critical for cell endurance. Therefore, cells should have a perceptive system that notifies about fluctuations in the amounts of certain components and an executive system that efficiently restores their precise levels. At least one mechanism that evolution has employed for this task is regulation of 3′-UTR length for microRNA targeting. Here we show that in Drosophila the microRNA complex miR-310s acts as an executive mechanism to buffer levels of the muscular dystrophy-associated extracellular matrix receptor dystroglycan via its alternative 3′-UTR. miR-310s gene expression fluctuates depending on dystroglycan amounts and nitric oxide signalling, which perceives dystroglycan levels and regulates microRNA gene expression. Aberrant levels of dystroglycan or deficiencies in miR-310s and nitric oxide signalling result in cobblestone brain appearance, resembling human lissencephaly type II phenotype. PMID:25232965

  20. An alternative host matrix based on iron phosphate glasses for the vitrification of specialized nuclear waste forms. Annual progress report, September 15, 1996--September 14, 1997

    SciTech Connect

    Day, D.E.; Ray, C.S.; Marasinghe, K.

    1997-09-23

    'Objectives of this project are to: (1) investigate the glass composition and processing conditions that yield optimum properties for iron phosphate glasses for vitrifying radioactive waste, (2) determine the atomic structure of iron phosphate glasses and the structure-property relationships, (3) determine how the physical and structural properties of iron phosphate glasses are affected by the addition of simulated high level nuclear waste components, and (4) investigate the process and products of devitrification of iron phosphate waste forms. The glass forming ability of about 125 iron phosphate melts has been investigated in different oxidizing to reducing atmospheres using various iron oxide raw materials such as Fe{sub 2}O{sub 3}, FeO, Fe{sub 3}O{sub 4}, and FeC{sub 2}O{sub 4} 2H{sub 2}O. The chemical durability, redox equilibria between Fe(II) and Fe(III), crystallization behavior and structural features for these glasses and their crystalline forms have been investigated using a variety of techniques including Mossbauer spectroscopy, X-ray absorption spectroscopy (XAS), X-ray photoelectron spectroscopy (XPS), Extended x-ray absorption fine structure (EXAFS) and X-ray absorption near edge structure (XANES) analysis, differential thermal and thermogravimetric analysis (DTA/TGA), and X-ray and neutron diffraction.'

  1. First report of Oregon grape (Mahonia aquifolium) as an alternate host for the wheat stripe rust pathogen (Puccinia striiformis f. sp. tritici) under artificial inoculation

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Cereal rusts are heteroecious fungi requiring cereal crops and other unrelated host species to complete their life cycle. Puccinia striiformis Westend. f. sp. tritici Erikss. (Pst), the wheat stripe rust pathogen, has five distinct spore types. Although wheat has been recognized as the primary host...

  2. Stromal matrix metalloprotease-13 knockout alters Collagen I structure at the tumor-host interface and increases lung metastasis of C57BL/6 syngeneic E0771 mammary tumor cells

    PubMed Central

    2013-01-01

    Background Matrix metalloproteases and collagen are key participants in breast cancer, but their precise roles in cancer etiology and progression remain unclear. MMP13 helps regulate collagen structure and has been ascribed largely harmful roles in cancer, but some studies demonstrate that MMP13 may also protect against tumor pathology. Other studies indicate that collagen’s organizational patterns at the breast tumor-host interface influence metastatic potential. Therefore we investigated how MMP13 modulates collagen I, a principal collagen subtype in breast tissue, and affects tumor pathology and metastasis in a mouse model of breast cancer. Methods Tumors were implanted into murine mammary tissues, and their growth analyzed in Wildtype and MMP13 KO mice. Following extraction, tumors were analyzed for collagen I levels and collagen I macro- and micro-structural properties at the tumor-host boundary using immunocytochemistry and two-photon and second harmonic generation microscopy. Lungs were analyzed for metastases counts, to correlate collagen I changes with a clinically significant functional parameter. Statistical analyses were performed by t-test, analysis of variance, or Wilcoxon-Mann–Whitney tests as appropriate. Results We found that genetic ablation of host stromal MMP13 led to: 1. Increased mammary tumor collagen I content, 2. Marked changes in collagen I spatial organization, and 3. Altered collagen I microstructure at the tumor-host boundary, as well as 4. Increased metastasis from the primary mammary tumor to lungs. Conclusions These results implicate host MMP13 as a key regulator of collagen I structure and metastasis in mammary tumors, thus making it an attractive potential therapeutic target by which we might alter metastatic potential, one of the chief determinants of clinical outcome in breast cancer. In addition to identifying stromal MMP13 is an important regulator of the tumor microenvironment and metastasis, these results also suggest

  3. Differences in performance and transcriptome-wide gene expression associated with Rhagoletis (Diptera: Tephritidae) larvae feeding in alternate host fruit environments.

    PubMed

    Ragland, Gregory J; Almskaar, Kristin; Vertacnik, Kim L; Gough, Harlan M; Feder, Jeffrey L; Hahn, Daniel A; Schwarz, Dietmar

    2015-06-01

    Host race formation, the establishment of new populations using novel resources, is a major hypothesized mechanism of ecological speciation, especially in plant-feeding insects. The initial stages of host race formation will often involve phenotypic plasticity on the novel resource, with subsequent genetically based adaptations enhancing host-associated fitness differences. Several studies have explored the physiology of the plastic responses of insects to novel host environments. However, the mechanisms underlying evolved differences among host races and species remain poorly understood. Here, we demonstrate a reciprocal larval performance difference between two closely related species of Rhagoletis flies, R. pomonella and R. zephyria, specialized for feeding in apple and snowberry fruit, respectively. Microarray analysis of fly larvae feeding in apples versus snowberries revealed patterns of transcriptome-wide differential gene expression consistent with both plastic and evolved responses to the different fruit resources, most notably for detoxification-related genes such as cytochrome p450s. Transcripts exhibiting evolved expression differences between species tended to also demonstrate plastic responses to fruit environment. The observed pattern suggests that Rhagoletis larvae exhibit extensive plasticity in gene expression in response to novel fruit that may potentiate shifts to new hosts. Subsequent selection, particularly selection to suppress initially costly plastic responses, could account for the evolved expression differences observed between R. pomonella and R. zephyria, creating specialized races and new fly species. Thus, genetically based ecological adaptations generating new biodiversity may often evolve from initial plastic responses in gene expression to the challenges posed by novel environments. PMID:25851077

  4. Photon-gated persistent spectral hole burning by electron transfer from a doped donor to an acceptor branched to a host polymer matrix

    NASA Astrophysics Data System (ADS)

    Suzuki, H.; Nishi, T.; Shimada, T.; Hiratsuka, H.

    1993-01-01

    Two-color photon-gated persistent spectral hole burning (PSHB) via donor-acceptor electron transfer is reported in systems where the acceptor, 10-chloroanthracene, was intentionally branched to a side chain of the poly(methylmethacrylate) (PMMA) host polymer while the donor, metal-free tetraphenylporphine, was dispersed in the polymer. The systems, which had an acceptor concentration of up to 10-1 M, were prepared without aggregation of the acceptor. Spectral holes were burnt in the Qx(0,0) absorption band of the donor when the systems were simultaneously irradiated with a frequency-selective excitation (duration: 500 ps; energy: 200 nJ/cm2) and a gating excitation (wavelength: 514.5 nm; duration: 33 ms; energy: 14 μJ/cm2). The difference absorption spectrum between the unburned absorption spectrum and one recorded after photon-gated PSHB has confirmed that the hole formation mechanism is donor-acceptor electron transfer from a photoexcited donor to a ground-state branched acceptor. The thermal stability of burnt holes measured with a temperature cycling experiment increased when the acceptor was branched into PMMA. The effect of acceptor branching on the PSHB characteristics is discussed with reference to those for an acceptor-doped system.

  5. Dendrimer-carbon nanotube layer-by-layer film as an efficient host matrix for electrogeneration of PtCo electrocatalysts.

    PubMed

    Gasparotto, Luiz H S; Castelhano, André L B; Silva, Anielle C A; Dantas, Noelio O; Oliveira, Osvaldo N; Siqueira, José R

    2014-02-14

    In this paper we demonstrate that layer-by-layer (LbL) films of polyamidoamine (PAMAM) dendrimers and single-walled carbon nanotubes (SWCNTs) are efficient for controlling the morphology of electrogenerated cobalt (Co) and the platinum-cobalt (PtCo) alloy. While Co grew to the micrometer scale and poorly covered the ITO substrate, with the LbL matrix it was kept in the nanoscale regime and provided full substrate coverage. Pt-decorated Co nanoparticles were then generated by applying a single potential pulse in a solution containing simultaneously Co and Pt ions. Segregation of Pt and Co deposits was observed in field emission gun (FEG) images, but the PtCo alloy was probably formed to some extent according to X-ray diffraction analysis. The PtCo-LbL hybrid exhibited superior catalytic activity toward H2O2 reduction compared to the Pt-modified LbL film, which opens new prospects for applications in biosensing and fuel cells. PMID:24352729

  6. Single amino acid changes in the 6K1-CI region can promote the alternative adaptation of Prunus- and Nicotiana-propagated Plum pox virus C isolates to either host.

    PubMed

    Calvo, María; Malinowski, Tadeusz; García, Juan Antonio

    2014-02-01

    Plum pox virus (PPV) C is one of the less common PPV strains and specifically infects cherry trees in nature. Making use of two PPV-C isolates that display different pathogenicity features, i.e., SwCMp, which had been adapted to Nicotiana species, and BY101, which had been isolated from cherry rootstock L2 (Prunus lannesiana) and propagated only in cherry species, we have generated two infective full-length cDNA clones in order to determine which viral factors are involved in the adaptation to each host. According to our results, the C-P3(PIPO)/6K1/N-CI (cylindrical inclusion) region contains overlapping but not coincident viral determinants involved in symptoms development, local viral amplification, and systemic movement capacity. Amino acid changes in this region promoting the adaptation to N. benthamiana or P. avium have trade-off effects in the alternative host. In both cases, adaptation can be achieved through single amino acid changes in the NIapro protease recognition motif between 6K1 and CI or in nearby sequences. Thus, we hypothesize that the potyvirus polyprotein processing could depend on specific host factors and the adaptation of PPV-C isolates to particular hosts relies on a fine regulation of the proteolytic cleavage of the 6K1-CI junction. PMID:24200075

  7. Role of the Emp Pilus Subunits of Enterococcus faecium in Biofilm Formation, Adherence to Host Extracellular Matrix Components, and Experimental Infection.

    PubMed

    Montealegre, Maria Camila; Singh, Kavindra V; Somarajan, Sudha R; Yadav, Puja; Chang, Chungyu; Spencer, Robert; Sillanpää, Jouko; Ton-That, Hung; Murray, Barbara E

    2016-05-01

    Enterococcus faecium is an important cause of hospital-associated infections, including urinary tract infections (UTIs), bacteremia, and infective endocarditis. Pili have been shown to play a role in the pathogenesis of Gram-positive bacteria, including E. faecium We previously demonstrated that a nonpiliated ΔempABC::cat derivative of E. faecium TX82 was attenuated in biofilm formation and in a UTI model. Here, we studied the contributions of the individual pilus subunits EmpA, EmpB, and EmpC to pilus architecture, biofilm formation, adherence to extracellular matrix (ECM) proteins, and infection. We identified EmpA as the tip of the pili and found that deletion of empA reduced biofilm formation to the same level as deletion of the empABC operon, a phenotype that was restored by reconstituting in situ the empA gene. Deletion of empB also caused a reduction in biofilm, while EmpC was found to be dispensable. Significant reductions in adherence to fibrinogen and collagen type I were observed with deletion of empA and empB, while deletion of empC had no adherence defect. Furthermore, we showed that each deletion mutant was significantly attenuated in comparison to the isogenic parental strain, TX82, in a mixed-inoculum UTI model (P < 0.001 to 0.048), that reconstitution of empA restored virulence in the UTI model, and that deletion of empA also resulted in attenuation in an infective endocarditis model (P = 0.0088). Our results indicate that EmpA and EmpB, but not EmpC, contribute to biofilm and adherence to ECM proteins; however, all the Emp pilins are important for E. faecium to cause infection in the urinary tract. PMID:26930703

  8. The role of alternate hosts in the ecology and life history of Hematodinium sp., a parasitic dinoflagellate of the blue crab (Callinectes sapidus).

    PubMed

    Lohan, Katrina M Pagenkopp; Reece, Kimberly S; Miller, Terrence L; Wheeler, Kersten N; Small, Hamish J; Shields, Jeffrey D

    2012-02-01

    Hematodinium sp. infections are relatively common in some American blue crab (Callinectes sapidus) populations in estuaries of the western Atlantic Ocean. Outbreaks of disease caused by Hematodinium sp. can be extensive and can cause substantial mortalities in blue crab populations in high salinities. We examined several species of crustaceans to determine if the same species of Hematodinium that infects C. sapidus is found in other crustaceans from the same localities. Over a 2-yr period, 1,829 crustaceans were collected from the Delmarva Peninsula, Virginia, examined for the presence of infections. A portion of the first internal transcribed spacer (ITS1) region of the ribosomal RNA (rRNA) gene complex from Hematodinium sp. was amplified and sequences were compared among 35 individual crustaceans putatively infected with the parasite, as determined by microscopic examination, and 4 crustaceans putatively infected based only on PCR analysis. Of the 18 crustacean species examined, 5 were infected with Hematodinium sp. after microscopic examination and PCR analysis, including 3 new host records, and an additional species was positive only via PCR analysis. The ITS1 rRNA sequences of Hematodinium sp. from the infected crustaceans were highly similar to each other and to that reported from C. sapidus (>98%). The similarity among these ITS1 sequences and similarities in the histopathology of infected hosts is evidence that the same species of Hematodinium found in C. sapidus infects a broad range of crustaceans along the Delmarva Peninsula. Our data indicate that the species of Hematodinium found in blue crabs from estuaries along the east coast of North America is a host generalist, capable of infecting hosts in different families within the Order Decapoda. Additionally, evidence indicates that it may be capable of infecting crustaceans within the Order Amphipoda. PMID:21812642

  9. Differential impacts of juvenile hormone, soldier head extract and alternate caste phenotypes on host and symbiont transcriptome composition in the gut of the termite Reticulitermes flavipes

    PubMed Central

    2013-01-01

    Background Termites are highly eusocial insects and show a division of labor whereby morphologically distinct individuals specialize in distinct tasks. In the lower termite Reticulitermes flavipes (Rhinotermitidae), non-reproducing individuals form the worker and soldier castes, which specialize in helping (e.g., brood care, cleaning, foraging) and defense behaviors, respectively. Workers are totipotent juveniles that can either undergo status quo molts or develop into soldiers or neotenic reproductives. This caste differentiation can be regulated by juvenile hormone (JH) and primer pheromones contained in soldier head extracts (SHE). Here we offered worker termites a cellulose diet treated with JH or SHE for 24-hr, or held them with live soldiers (LS) or live neotenic reproductives (LR). We then determined gene expression profiles of the host termite gut and protozoan symbionts concurrently using custom cDNA oligo-microarrays containing 10,990 individual ESTs. Results JH was the most influential treatment (501 total ESTs affected), followed by LS (24 ESTs), LR (12 ESTs) and SHE treatments (6 ESTs). The majority of JH up- and downregulated ESTs were of host and symbiont origin, respectively; in contrast, SHE, LR and LS treatments had more uniform impacts on host and symbiont gene expression. Repeat “follow-up” bioassays investigating combined JH + SHE impacts in relation to individual JH and SHE treatments on a subset of array-positive genes revealed (i) JH and SHE treatments had opposite impacts on gene expression and (ii) JH + SHE impacts on gene expression were generally intermediate between JH and SHE. Conclusions Our results show that JH impacts hundreds of termite and symbiont genes within 24-hr, strongly suggesting a role for the termite gut in JH-dependent caste determination. Additionally, differential impacts of SHE and LS treatments were observed that are in strong agreement with previous studies that specifically investigated soldier caste

  10. Host Responses to Biofilm.

    PubMed

    Watters, C; Fleming, D; Bishop, D; Rumbaugh, K P

    2016-01-01

    From birth to death the human host immune system interacts with bacterial cells. Biofilms are communities of microbes embedded in matrices composed of extracellular polymeric substance (EPS), and have been implicated in both the healthy microbiome and disease states. The immune system recognizes many different bacterial patterns, molecules, and antigens, but these components can be camouflaged in the biofilm mode of growth. Instead, immune cells come into contact with components of the EPS matrix, a diverse, hydrated mixture of extracellular DNA (bacterial and host), proteins, polysaccharides, and lipids. As bacterial cells transition from planktonic to biofilm-associated they produce small molecules, which can increase inflammation, induce cell death, and even cause necrosis. To survive, invading bacteria must overcome the epithelial barrier, host microbiome, complement, and a variety of leukocytes. If bacteria can evade these initial cell populations they have an increased chance at surviving and causing ongoing disease in the host. Planktonic cells are readily cleared, but biofilms reduce the effectiveness of both polymorphonuclear neutrophils and macrophages. In addition, in the presence of these cells, biofilm formation is actively enhanced, and components of host immune cells are assimilated into the EPS matrix. While pathogenic biofilms contribute to states of chronic inflammation, probiotic Lactobacillus biofilms cause a negligible immune response and, in states of inflammation, exhibit robust antiinflammatory properties. These probiotic biofilms colonize and protect the gut and vagina, and have been implicated in improved healing of damaged skin. Overall, biofilms stimulate a unique immune response that we are only beginning to understand. PMID:27571696

  11. An alternative improved method for the homogeneous dispersion of CNTs in Cu matrix for the fabrication of Cu/CNTs composites

    NASA Astrophysics Data System (ADS)

    Lal, Maneet; Singhal, S. K.; Sharma, Indu; Mathur, R. B.

    2013-02-01

    Copper has a wide range of applications due to its excellent properties (high thermal and electrical conductivity). Carbon nanotubes (CNTs) are widely used as a reinforcing material due to their superior properties. Copper/Carbon nanotube (Cu/CNTs) composites show enhanced mechanical, electrical and thermal properties as compared to pure Cu and Cu composites. Hence, Cu/CNTs composites have tremendous applications. Cu/CNTs are being developed for use as antifungal and antimicrobial agents, which can lead to their further use in biomedical devices and implant materials. The versatility of this material is such that Cu/CNTs are being developed for use in ultra-large scale integrated circuits for use in the latest integrated circuits and semiconductor chips. The composite material is being used as heat sinks for various industries. Cu/CNTs are now also being employed as catalysts for various industrial reactions. Fuel cell electrodes based on Cu/CNTs are being developed to replace expensive Pt/Pd-based electrodes, currently being used. Another application in the energy sector is the use of Cu/CNTs in direct methanol fuel cells and in methanol gas reforming for H2 production. These extensive applications provided motivation for the current work. However, these applications can only be realized if a stable and uniform Cu/CNTs composite powder can be made. The challenges in fabricating Cu/CNTs composites are: (1) homogeneous dispersion of CNTs in Cu matrix, (2) interfacial bonding between CNTs and Cu matrix and (3) retention of structural integrity of CNTs. Powder metallurgy (PM) has been widely used, but dispersion of Cu/CNTs remains an issue. We employed the molecular level mixing method (MLM), coupled with high energy ball milling (BM) to overcome above mentioned issues. To the best of our knowledge, this is a new process for the homogeneous dispersion of CNTs in copper and has been reported for the first time. To produce a homogenous mixture of Cu and CNTs, a

  12. HostPhinder: A Phage Host Prediction Tool

    PubMed Central

    Villarroel, Julia; Kleinheinz, Kortine Annina; Jurtz, Vanessa Isabell; Zschach, Henrike; Lund, Ole; Nielsen, Morten; Larsen, Mette Voldby

    2016-01-01

    The current dramatic increase of antibiotic resistant bacteria has revitalised the interest in bacteriophages as alternative antibacterial treatment. Meanwhile, the development of bioinformatics methods for analysing genomic data places high-throughput approaches for phage characterization within reach. Here, we present HostPhinder, a tool aimed at predicting the bacterial host of phages by examining the phage genome sequence. Using a reference database of 2196 phages with known hosts, HostPhinder predicts the host species of a query phage as the host of the most genomically similar reference phages. As a measure of genomic similarity the number of co-occurring k-mers (DNA sequences of length k) is used. Using an independent evaluation set, HostPhinder was able to correctly predict host genus and species for 81% and 74% of the phages respectively, giving predictions for more phages than BLAST and significantly outperforming BLAST on phages for which both had predictions. HostPhinder predictions on phage draft genomes from the INTESTI phage cocktail corresponded well with the advertised targets of the cocktail. Our study indicates that for most phages genomic similarity correlates well with related bacterial hosts. HostPhinder is available as an interactive web service [1] and as a stand alone download from the Docker registry [2]. PMID:27153081

  13. HostPhinder: A Phage Host Prediction Tool.

    PubMed

    Villarroel, Julia; Kleinheinz, Kortine Annina; Jurtz, Vanessa Isabell; Zschach, Henrike; Lund, Ole; Nielsen, Morten; Larsen, Mette Voldby

    2016-01-01

    The current dramatic increase of antibiotic resistant bacteria has revitalised the interest in bacteriophages as alternative antibacterial treatment. Meanwhile, the development of bioinformatics methods for analysing genomic data places high-throughput approaches for phage characterization within reach. Here, we present HostPhinder, a tool aimed at predicting the bacterial host of phages by examining the phage genome sequence. Using a reference database of 2196 phages with known hosts, HostPhinder predicts the host species of a query phage as the host of the most genomically similar reference phages. As a measure of genomic similarity the number of co-occurring k-mers (DNA sequences of length k) is used. Using an independent evaluation set, HostPhinder was able to correctly predict host genus and species for 81% and 74% of the phages respectively, giving predictions for more phages than BLAST and significantly outperforming BLAST on phages for which both had predictions. HostPhinder predictions on phage draft genomes from the INTESTI phage cocktail corresponded well with the advertised targets of the cocktail. Our study indicates that for most phages genomic similarity correlates well with related bacterial hosts. HostPhinder is available as an interactive web service [1] and as a stand alone download from the Docker registry [2]. PMID:27153081

  14. Matrix superpotentials

    NASA Astrophysics Data System (ADS)

    Nikitin, Anatoly G.; Karadzhov, Yuri

    2011-07-01

    We present a collection of matrix-valued shape invariant potentials which give rise to new exactly solvable problems of SUSY quantum mechanics. It includes all irreducible matrix superpotentials of the generic form W=kQ+\\frac{1}{k} R+P, where k is a variable parameter, Q is the unit matrix multiplied by a real-valued function of independent variable x, and P and R are the Hermitian matrices depending on x. In particular, we recover the Pron'ko-Stroganov 'matrix Coulomb potential' and all known scalar shape invariant potentials of SUSY quantum mechanics. In addition, five new shape invariant potentials are presented. Three of them admit a dual shape invariance, i.e. the related Hamiltonians can be factorized using two non-equivalent superpotentials. We find discrete spectrum and eigenvectors for the corresponding Schrödinger equations and prove that these eigenvectors are normalizable.

  15. Host Density and Competency Determine the Effects of Host Diversity on Trematode Parasite Infection

    PubMed Central

    Wojdak, Jeremy M.; Edman, Robert M.; Wyderko, Jennie A.; Zemmer, Sally A.; Belden, Lisa K.

    2014-01-01

    Variation in host species composition can dramatically alter parasite transmission in natural communities. Whether diverse host communities dilute or amplify parasite transmission is thought to depend critically on species traits, particularly on how hosts affect each other’s densities, and their relative competency as hosts. Here we studied a community of potential hosts and/or decoys (i.e. non-competent hosts) for two trematode parasite species, Echinostoma trivolvis and Ribeiroia ondatrae, which commonly infect wildlife across North America. We manipulated the density of a focal host (green frog tadpoles, Rana clamitans), in concert with manipulating the diversity of alternative species, to simulate communities where alternative species either (1) replace the focal host species so that the total number of individuals remains constant (substitution) or (2) add to total host density (addition). For E. trivolvis, we found that total parasite transmission remained roughly equal (or perhaps decreased slightly) when alternative species replaced focal host individuals, but parasite transmission was higher when alternative species were added to a community without replacing focal host individuals. Given the alternative species were roughly equal in competency, these results are consistent with current theory. Remarkably, both total tadpole and per-capita tadpole infection intensity by E. trivolvis increased with increasing intraspecific host density. For R. ondatrae, alternative species did not function as effective decoys or hosts for parasite infective stages, and the diversity and density treatments did not produce clear changes in parasite transmission, although high tank to tank variation in R. ondatrae infection could have obscured patterns. PMID:25119568

  16. Sync Matrix

    Energy Science and Technology Software Center (ESTSC)

    2004-12-31

    Sync Matrix provides a graphic display of the relationships among all of the response activities of each jurisdiction. This is accomplished through software that organizes and displays the activities by jurisdiction, function, and time for easy review and analysis. The software can also integrate the displays of multiple jurisdictions to allow examination of the total response.

  17. Nuclear Matrix protein SMAR1 represses HIV-1 LTR mediated transcription through chromatin remodeling

    SciTech Connect

    Sreenath, Kadreppa; Pavithra, Lakshminarasimhan; Singh, Sandeep; Sinha, Surajit; Dash, Prasanta K.; Siddappa, Nagadenahalli B.; Ranga, Udaykumar; Mitra, Debashis; Chattopadhyay, Samit

    2010-04-25

    Nuclear Matrix and MARs have been implicated in the transcriptional regulation of host as well as viral genes but their precise role in HIV-1 transcription remains unclear. Here, we show that > 98% of HIV sequences contain consensus MAR element in their promoter. We show that SMAR1 binds to the LTR MAR and reinforces transcriptional silencing by tethering the LTR MAR to nuclear matrix. SMAR1 associated HDAC1-mSin3 corepressor complex is dislodged from the LTR upon cellular activation by PMA/TNFalpha leading to an increase in the acetylation and a reduction in the trimethylation of histones, associated with the recruitment of RNA Polymerase II on the LTR. Overexpression of SMAR1 lead to reduction in LTR mediated transcription, both in a Tat dependent and independent manner, resulting in a decreased virion production. These results demonstrate the role of SMAR1 in regulating viral transcription by alternative compartmentalization of LTR between the nuclear matrix and chromatin.

  18. Alternative security

    SciTech Connect

    Weston, B.H. )

    1990-01-01

    This book contains the following chapters: The Military and Alternative Security: New Missions for Stable Conventional Security; Technology and Alternative Security: A Cherished Myth Expires; Law and Alternative Security: Toward a Just World Peace; Politics and Alternative Security: Toward a More Democratic, Therefore More Peaceful, World; Economics and Alternative Security: Toward a Peacekeeping International Economy; Psychology and Alternative Security: Needs, Perceptions, and Misperceptions; Religion and Alternative Security: A Prophetic Vision; and Toward Post-Nuclear Global Security: An Overview.

  19. Differential reproductive success favours strong host preference in a highly specialized brood parasite

    PubMed Central

    De Mársico, María C; Reboreda, Juan C

    2008-01-01

    Obligate avian brood parasites show dramatic variation in the degree to which they are host specialists or host generalists. The screaming cowbird Molothrus rufoaxillaris is one of the most specialized brood parasites, using a single host, the bay-winged cowbird (Agelaioides badius) over most of its range. Coevolutionary theory predicts increasing host specificity the longer the parasite interacts with a particular avian community, as hosts evolve defences that the parasite cannot counteract. According to this view, host specificity can be maintained if screaming cowbirds avoid parasitizing potentially suitable hosts that have developed effective defences against parasitic females or eggs. Specialization may also be favoured, even in the absence of host defences, if the parasite's reproductive success in alternative hosts is lower than that in the main host. We experimentally tested these hypotheses using as alternative hosts two suitable but unparasitized species: house wrens (Troglodytes aedon) and chalk-browed mockingbirds (Mimus saturninus). We assessed host defences against parasitic females and eggs, and reproductive success of the parasite in current and alternative hosts. Alternative hosts did not discriminate against screaming cowbird females or eggs. Egg survival and hatching success were similarly high in current and alternative hosts, but the survival of parasitic chicks was significantly lower in alternative hosts. Our results indicate that screaming cowbirds have the potential to colonize novel hosts, but higher reproductive success in the current host may favour host fidelity. PMID:18647716

  20. Optical devices having flakes suspended in a host fluid to provide a flake/fluid system providing flakes with angularly dependent optical properties in response to an alternating current electric field due to the dielectric properties of the system

    DOEpatents

    Kosc, Tanya Z.; Marshall, Kenneth L.; Jacobs, Stephen D.

    2006-05-09

    Optical devices utilizing flakes (also called platelets) suspended in a host fluid have optical characteristics, such as reflective properties, which are angular dependent in response to an AC field. The reflectivity may be Bragg-like, and the characteristics are obtained through the use of flakes of liquid crystal material, such as polymer liquid crystal (PLC) materials including polymer cholesteric liquid crystal (PCLC) and polymer nematic liquid crystal (PNLC) material or birefringent polymers (BP). The host fluid may be propylene carbonate, poly(ethylene glycol) or other fluids or fluid mixtures having fluid conductivity to support conductivity in the flake/host system. AC field dependent rotation of 90.degree. can be obtained at rates and field intensities dependent upon the frequency and magnitude of the AC field. The devices are useful in providing displays, polarizers, filters, spatial light modulators and wherever switchable polarizing, reflecting, and transmission properties are desired.

  1. Host Selection of Microbiota via Differential Adhesion.

    PubMed

    McLoughlin, Kirstie; Schluter, Jonas; Rakoff-Nahoum, Seth; Smith, Adrian L; Foster, Kevin R

    2016-04-13

    The host epithelium is the critical interface with microbial communities, but the mechanisms by which the host regulates these communities are poorly understood. Here we develop the hypothesis that hosts use differential adhesion to select for and against particular members of their microbiota. We use an established computational, individual-based model to study the impact of host factors that regulate adhesion at the epithelial surface. Our simulations predict that host-mediated adhesion can increase the competitive advantage of microbes and create ecological refugia for slow-growing species. We show how positive selection via adhesion can be transformed into negative selection if the host secretes large quantities of a matrix such as mucus. Our work predicts that adhesion is a powerful mechanism for both positive and negative selection within the microbiota. We discuss molecules-mucus glycans and IgA-that affect microbe adhesion and identify testable predictions of the adhesion-as-selection model. PMID:27053168

  2. Deciphering mechanisms of staphylococcal biofilm evasion of host immunity

    PubMed Central

    Hanke, Mark L.; Kielian, Tammy

    2012-01-01

    Biofilms are adherent communities of bacteria contained within a complex matrix. Although host immune responses to planktonic staphylococcal species have been relatively well-characterized, less is known regarding immunity to staphylococcal biofilms and how they modulate anti-bacterial effector mechanisms when organized in this protective milieu. Previously, staphylococcal biofilms were thought to escape immune recognition on the basis of their chronic and indolent nature. Instead, we have proposed that staphylococcal biofilms skew the host immune response away from a proinflammatory bactericidal phenotype toward an anti-inflammatory, pro-fibrotic response that favors bacterial persistence. This possibility is supported by recent studies from our laboratory using a mouse model of catheter-associated biofilm infection, where S. aureus biofilms led to the accumulation of alternatively activated M2 macrophages that exhibit anti-inflammatory and pro-fibrotic properties. In addition, relatively few neutrophils were recruited into S. aureus biofilms, representing another mechanism that deviates from planktonic infections. However, it is important to recognize the diversity of biofilm infections, in that studies by others have demonstrated the induction of distinct immune responses during staphylococcal biofilm growth in other models, suggesting influences from the local tissue microenvironment. This review will discuss the immune defenses that staphylococcal biofilms evade as well as conceptual issues that remain to be resolved. An improved understanding of why the host immune response is unable to clear biofilm infections could lead to targeted therapies to reverse these defects and expedite biofilm clearance. PMID:22919653

  3. Host thin films incorporating nanoparticles

    NASA Astrophysics Data System (ADS)

    Qureshi, Uzma

    The focus of this research project was the investigation of the functional properties of thin films that incorporate a secondary nanoparticulate phase. In particular to assess if the secondary nanoparticulate material enhanced a functional property of the coating on glass. In order to achieve this, new thin film deposition methods were developed, namely use of nanopowder precursors, an aerosol assisted transport technique and an aerosol into atmospheric pressure chemical vapour deposition system. Aerosol assisted chemical vapour deposition (AACVD) was used to deposit 8 series of thin films on glass. Five different nanoparticles silver, gold, ceria, tungsten oxide and zinc oxide were tested and shown to successfully deposit thin films incorporating nanoparticles within a host matrix. Silver nanoparticles were synthesised and doped within a titania film by AACVD. This improved solar control properties. A unique aerosol assisted chemical vapour deposition (AACVD) into atmospheric pressure chemical vapour deposition (APCVD) system was used to deposit films of Au nanoparticles and thin films of gold nanoparticles incorporated within a host titania matrix. Incorporation of high refractive index contrast metal oxide particles within a host film altered the film colour. The key goal was to test the potential of nanopowder forms and transfer the suspended nanopowder via an aerosol to a substrate in order to deposit a thin film. Discrete tungsten oxide nanoparticles or ceria nanoparticles within a titanium dioxide thin film enhanced the self-cleaning and photo-induced super-hydrophilicity. The nanopowder precursor study was extended by deposition of zinc oxide thin films incorporating Au nanoparticles and also ZnO films deposited from a ZnO nanopowder precursor. Incorporation of Au nanoparticles within a VO: host matrix improved the thermochromic response, optical and colour properties. Composite VC/TiC and Au nanoparticle/V02/Ti02 thin films displayed three useful

  4. Host Plant Adaptation in Drosophila mettleri Populations

    PubMed Central

    Castrezana, Sergio; Bono, Jeremy M.

    2012-01-01

    The process of local adaptation creates diversity among allopatric populations, and may eventually lead to speciation. Plant-feeding insect populations that specialize on different host species provide an excellent opportunity to evaluate the causes of ecological specialization and the subsequent consequences for diversity. In this study, we used geographically separated Drosophila mettleri populations that specialize on different host cacti to examine oviposition preference for and larval performance on an array of natural and non-natural hosts (eight total). We found evidence of local adaptation in performance on saguaro cactus (Carnegiea gigantea) for populations that are typically associated with this host, and to chemically divergent prickly pear species (Opuntia spp.) in a genetically isolated population on Santa Catalina Island. Moreover, each population exhibited reduced performance on the alternative host. This finding is consistent with trade-offs associated with adaptation to these chemically divergent hosts, although we also discuss alternative explanations for this pattern. For oviposition preference, Santa Catalina Island flies were more likely to oviposit on some prickly pear species, but all populations readily laid eggs on saguaro. Experiments with non-natural hosts suggest that factors such as ecological opportunity may play a more important role than host plant chemistry in explaining the lack of natural associations with some hosts. PMID:22493678

  5. Host plant adaptation in Drosophila mettleri populations.

    PubMed

    Castrezana, Sergio; Bono, Jeremy M

    2012-01-01

    The process of local adaptation creates diversity among allopatric populations, and may eventually lead to speciation. Plant-feeding insect populations that specialize on different host species provide an excellent opportunity to evaluate the causes of ecological specialization and the subsequent consequences for diversity. In this study, we used geographically separated Drosophila mettleri populations that specialize on different host cacti to examine oviposition preference for and larval performance on an array of natural and non-natural hosts (eight total). We found evidence of local adaptation in performance on saguaro cactus (Carnegiea gigantea) for populations that are typically associated with this host, and to chemically divergent prickly pear species (Opuntia spp.) in a genetically isolated population on Santa Catalina Island. Moreover, each population exhibited reduced performance on the alternative host. This finding is consistent with trade-offs associated with adaptation to these chemically divergent hosts, although we also discuss alternative explanations for this pattern. For oviposition preference, Santa Catalina Island flies were more likely to oviposit on some prickly pear species, but all populations readily laid eggs on saguaro. Experiments with non-natural hosts suggest that factors such as ecological opportunity may play a more important role than host plant chemistry in explaining the lack of natural associations with some hosts. PMID:22493678

  6. Highly efficient direct aerobic oxidative esterification of cinnamyl alcohol with alkyl alcohols catalysed by gold nanoparticles incarcerated in a nanoporous polymer matrix: a tool for investigating the role of the polymer host.

    PubMed

    Buonerba, Antonio; Noschese, Annarita; Grassi, Alfonso

    2014-04-25

    The selective aerobic oxidation of cinnamyl alcohol to cinnamaldehyde, as well as direct oxidative esterification of this alcohol with primary and secondary aliphatic alcohols, were achieved with high chemoselectivity by using gold nanoparticles supported in a nanoporous semicrystalline multi-block copolymer matrix, which consisted of syndiotactic polystyrene-co-cis-1,4-polybutadiene. The cascade reaction that leads to the alkyl cinnamates occurs through two oxidation steps: the selective oxidation of cinnamyl alcohol to cinnamaldehyde, followed by oxidation of the hemiacetal that results from the base-catalysed reaction of cinnamaldehyde with an aliphatic alcohol. The rate constants for the two steps were evaluated in the temperature range 10-45 °C. The cinnamyl alcohol oxidation is faster than the oxidative esterification of cinnamaldehyde with methanol, ethanol, 2-propanol, 1-butanol, 1-hexanol or 1-octanol. The rate constants of the latter reaction are pseudo-zero order with respect to the aliphatic alcohol and decrease as the bulkiness of the alcohol is increased. The activation energy (Ea) for the two oxidation steps was calculated for esterification of cinnamyl alcohol with 1-butanol (Ea = 57.8±11.5 and 62.7±16.7 kJ mol(-1) for the first and second step, respectively). The oxidative esterification of cinnamyl alcohol with 2-phenylethanol follows pseudo-first-order kinetics with respect to 2-phenylethanol and is faster than observed for other alcohols because of fast diffusion of the aromatic alcohol in the crystalline phase of the support. The kinetic investigation allowed us to assess the role of the polymer support in the determination of both high activity and selectivity in the title reaction. PMID:24644103

  7. Candida Biofilms and the Host: Models and New Concepts for Eradication

    PubMed Central

    Tournu, Hélène; Van Dijck, Patrick

    2012-01-01

    Biofilms define mono- or multispecies communities embedded in a self-produced protective matrix, which is strongly attached to surfaces. They often are considered a general threat not only in industry but also in medicine. They constitute a permanent source of contamination, and they can disturb the proper usage of the material onto which they develop. This paper relates to some of the most recent approaches that have been elaborated to eradicate Candida biofilms, based on the vast effort put in ever-improving models of biofilm formation in vitro and in vivo, including novel flow systems, high-throughput techniques and mucosal models. Mixed biofilms, sustaining antagonist or beneficial cooperation between species, and their interplay with the host immune system are also prevalent topics. Alternative strategies against biofilms include the lock therapy and immunotherapy approaches, and material coating and improvements. The host-biofilm interactions are also discussed, together with their potential applications in Candida biofilm elimination. PMID:22164167

  8. Alternate Alternates: A Medley of Alternate Assessments.

    ERIC Educational Resources Information Center

    Burdette, Paula J.; Olsen, Ken

    This paper highlights eight states that have implemented alternate assessments for children with disabilities who cannot participate in their state and district-wide assessment programs. The alternate assessment systems in Delaware, Florida, Georgia, Indiana, Minnesota, North Dakota, Utah, and West Virginia are briefly described, along with their…

  9. Alternative Therapies

    MedlinePlus

    ... Late Effects of Poliomyelitis for Physicians and Survivors © Alternative Therapies Alternative therapies, also called complementary, can support ... of motion, pain, and fatigue are often reported. Energy work includes acupuncture and acupressure, traditional Chinese medicine ...

  10. Method of determining lanthanidies in a transition element host

    DOEpatents

    De Kalb, Edward L.; Fassel, Velmer A.

    1976-02-03

    A phosphor composition contains a lanthanide activator element within a host matrix having a transition element as a major component. The host matrix is composed of certain rare earth phosphates or vanadates such as YPO.sub.4 with a portion of the rare earth replaced with one or more of the transition elements. On X-ray or other electromagnetic excitation, trace lanthanide impurities or additives within the phosphor are spectrometrically determined from their characteristic luminescence.

  11. Layered graphitic carbon host formation during liquid-free solid state growth of metal pyrophosphates.

    PubMed

    Díaz, Carlos; Valenzuela, María Luisa; Lavayen, Vladimir; O'Dwyer, Colm

    2012-06-01

    We report a successful ligand- and liquid-free solid state route to form metal pyrophosphates within a layered graphitic carbon matrix through a single step approach involving pyrolysis of previously synthesized organometallic derivatives of a cyclotriphosphazene. In this case, we show how single crystal Mn(2)P(2)O(7) can be formed on either the micro- or the nanoscale in the complete absence of solvents or solutions by an efficient combustion process using rationally designed macromolecular trimer precursors, and present evidence and a mechanism for layered graphite host formation. Using in situ Raman spectroscopy, infrared spectroscopy, X-ray diffraction, high resolution electron microscopy, thermogravimetric and differential scanning calorimetric analysis, and near-edge X-ray absorption fine structure examination, we monitor the formation process of a layered, graphitic carbon in the matrix. The identification of thermally and electrically conductive graphitic carbon host formation is important for the further development of this general ligand-free synthetic approach for inorganic nanocrystal growth in the solid state, and can be extended to form a range of transition metals pyrophosphates. For important energy storage applications, the method gives the ability to form oxide and (pyro)phosphates within a conductive, intercalation possible, graphitic carbon as host-guest composites directly on substrates for high rate Li-ion battery and emerging alternative positive electrode materials. PMID:22587306

  12. Summary of laser speckle photogrammetry for HOST

    NASA Technical Reports Server (NTRS)

    Pollack, Frank G.

    1986-01-01

    High temperature static strain measurement capability is important for the success of the HOST program. As part of the NASA Lewis effort to develop the technology for improved hot-section durability, the HOST instrumentation program has, as a major goal, the development of methods for measuring strain at high temperature. Development work includes both improvements in resistance strain-gauge technology and, as an alternative approach, the development of optical techniques for high temperature strain measurement.

  13. High-frequency matrix converter with square wave input

    SciTech Connect

    Carr, Joseph Alexander; Balda, Juan Carlos

    2015-03-31

    A device for producing an alternating current output voltage from a high-frequency, square-wave input voltage comprising, high-frequency, square-wave input a matrix converter and a control system. The matrix converter comprises a plurality of electrical switches. The high-frequency input and the matrix converter are electrically connected to each other. The control system is connected to each switch of the matrix converter. The control system is electrically connected to the input of the matrix converter. The control system is configured to operate each electrical switch of the matrix converter converting a high-frequency, square-wave input voltage across the first input port of the matrix converter and the second input port of the matrix converter to an alternating current output voltage at the output of the matrix converter.

  14. Bottom-Up and Top-Down Solid-State NMR Approaches for Bacterial Biofilm Matrix Composition

    PubMed Central

    Cegelski, Lynette

    2015-01-01

    The genomics and proteomics revolutions have been enormously successful in providing crucial “parts lists” for biological systems. Yet, formidable challenges exist in generating complete descriptions of how the parts function and assemble into macromolecular complexes and whole-cell assemblies. Bacterial biofilms are complex multicellular bacterial communities protected by a slime-like extracellular matrix that confers protection to environmental stress and enhances resistance to antibiotics and host defenses. As a non-crystalline, insoluble, heterogeneous assembly, the biofilm extracellular matrix poses a challenge to compositional analysis by conventional methods. In this Perspective, bottom-up and top-down solid-state NMR approaches are described for defining chemical composition in complex macrosystems. The “sum-of-theparts” bottom-up approach was introduced to examine the amyloid-integrated biofilms formed by E. coli and permitted the first determination of the composition of the intact extracellular matrix from a bacterial biofilm. An alternative top-down approach was developed to define composition in V. cholerae biofilms and relied on an extensive panel of NMR measurements to tease out specific carbon pools from a single sample of the intact extracellular matrix. These two approaches are widely applicable to other heterogeneous assemblies. For bacterial biofilms, quantitative parameters of matrix composition are needed to understand how biofilms are assembled, to improve the development of biofilm inhibitors, and to dissect inhibitor modes of action. Solid-state NMR approaches will also be invaluable in obtaining parameters of matrix architecture. PMID:25797008

  15. Bottom-up and top-down solid-state NMR approaches for bacterial biofilm matrix composition

    NASA Astrophysics Data System (ADS)

    Cegelski, Lynette

    2015-04-01

    The genomics and proteomics revolutions have been enormously successful in providing crucial "parts lists" for biological systems. Yet, formidable challenges exist in generating complete descriptions of how the parts function and assemble into macromolecular complexes and whole-cell assemblies. Bacterial biofilms are complex multicellular bacterial communities protected by a slime-like extracellular matrix that confers protection to environmental stress and enhances resistance to antibiotics and host defenses. As a non-crystalline, insoluble, heterogeneous assembly, the biofilm extracellular matrix poses a challenge to compositional analysis by conventional methods. In this perspective, bottom-up and top-down solid-state NMR approaches are described for defining chemical composition in complex macrosystems. The "sum-of-the-parts" bottom-up approach was introduced to examine the amyloid-integrated biofilms formed by Escherichia coli and permitted the first determination of the composition of the intact extracellular matrix from a bacterial biofilm. An alternative top-down approach was developed to define composition in Vibrio cholerae biofilms and relied on an extensive panel of NMR measurements to tease out specific carbon pools from a single sample of the intact extracellular matrix. These two approaches are widely applicable to other heterogeneous assemblies. For bacterial biofilms, quantitative parameters of matrix composition are needed to understand how biofilms are assembled, to improve the development of biofilm inhibitors, and to dissect inhibitor modes of action. Solid-state NMR approaches will also be invaluable in obtaining parameters of matrix architecture.

  16. Hybrid matrix fiber composites

    DOEpatents

    Deteresa, Steven J.; Lyon, Richard E.; Groves, Scott E.

    2003-07-15

    Hybrid matrix fiber composites having enhanced compressive performance as well as enhanced stiffness, toughness and durability suitable for compression-critical applications. The methods for producing the fiber composites using matrix hybridization. The hybrid matrix fiber composites include two chemically or physically bonded matrix materials, whereas the first matrix materials are used to impregnate multi-filament fibers formed into ribbons and the second matrix material is placed around and between the fiber ribbons that are impregnated with the first matrix material and both matrix materials are cured and solidified.

  17. Finding nonoverlapping substructures of a sparse matrix

    SciTech Connect

    Pinar, Ali; Vassilevska, Virginia

    2004-08-09

    Many applications of scientific computing rely on computations on sparse matrices, thus the design of efficient implementations of sparse matrix kernels is crucial for the overall efficiency of these applications. Due to the high compute-to-memory ratio and irregular memory access patterns, the performance of sparse matrix kernels is often far away from the peak performance on a modern processor. Alternative data structures have been proposed, which split the original matrix A into A{sub d} and A{sub s}, so that A{sub d} contains all dense blocks of a specified size in the matrix, and A{sub s} contains the remaining entries. This enables the use of dense matrix kernels on the entries of A{sub d} producing better memory performance. In this work, we study the problem of finding a maximum number of non overlapping rectangular dense blocks in a sparse matrix, which has not been studied in the sparse matrix community. We show that the maximum non overlapping dense blocks problem is NP-complete by using a reduction from the maximum independent set problem on cubic planar graphs. We also propose a 2/3-approximation algorithm for 2 times 2 blocks that runs in linear time in the number of nonzeros in the matrix. We discuss alternatives to rectangular blocks such as diagonal blocks and cross blocks and present complexity analysis and approximation algorithms.

  18. Alternate Rules of Association

    NASA Astrophysics Data System (ADS)

    Curtright, Thomas L.; Fairlie, David B.; Zachos, Cosmas K.

    2014-11-01

    The Weyl correspondence rule (107) is not unique: there are a host of alternate equivalent association rules which specify corresponding representations. All these representations with equivalent formalisms are typified by characteristic quasi-distribution functions and ⋆-products, all systematically inter-convertible among themselves. They have been surveyed comparatively and organized in [Lee95, BJ84], on the basis of seminal classification work by Cohen [Coh66, Coh76]. Like different coordinate transformations, they may be favored by virtue of their different characteristic properties in varying applications...

  19. Alternative Schools.

    ERIC Educational Resources Information Center

    Pritchett, Stanley; Kimsey, Steve

    2002-01-01

    Describes the design of the DeKalb Alternative School in Atlanta, Georgia, located in a renovated shopping center. Purchasing commercial land and renovating the existing building saved the school system time and money. (EV)

  20. Chemically modified tetracyclines: The novel host modulating agents

    PubMed Central

    Swamy, Devulapalli Narasimha; Sanivarapu, Sahitya; Moogla, Srinivas; Kapalavai, Vasavi

    2015-01-01

    Periodontal pathogens and destructive host responses are involved in the initiation and progression of periodontitis. The emergence of host response modulation as a treatment concept has resulted from our improved understanding of the pathogenesis of periodontal disease. A variety of drugs have been evaluated as host modulation agents (HMA), including Non Steroidal Anti Inflammatory Drugs (NSAIDS), bisphosphonates, tetracyclines, enamel matrix proteins and bone morphogenetic proteins. Chemically modified tetracyclines (CMTs) are one such group of drugs which have been viewed as potential host modulating agents by their anticollagenolytic property. The CMTs are designed to be more potent inhibitors of pro inflammatory mediators and can increase the levels of anti inflammatory mediators. PMID:26392682

  1. Chemically modified tetracyclines: The novel host modulating agents.

    PubMed

    Swamy, Devulapalli Narasimha; Sanivarapu, Sahitya; Moogla, Srinivas; Kapalavai, Vasavi

    2015-01-01

    Periodontal pathogens and destructive host responses are involved in the initiation and progression of periodontitis. The emergence of host response modulation as a treatment concept has resulted from our improved understanding of the pathogenesis of periodontal disease. A variety of drugs have been evaluated as host modulation agents (HMA), including Non Steroidal Anti Inflammatory Drugs (NSAIDS), bisphosphonates, tetracyclines, enamel matrix proteins and bone morphogenetic proteins. Chemically modified tetracyclines (CMTs) are one such group of drugs which have been viewed as potential host modulating agents by their anticollagenolytic property. The CMTs are designed to be more potent inhibitors of pro inflammatory mediators and can increase the levels of anti inflammatory mediators. PMID:26392682

  2. The Evolution of Viruses in Multi-Host Fitness Landscapes

    PubMed Central

    Elena, Santiago F; Agudelo-Romero, Patricia; Lalić, Jasna

    2009-01-01

    Provided that generalist viruses will have access to potentially unlimited hosts, the question is why most viruses specialize in few hosts. It has been suggested that selection should favor specialists because there are tradeoffs limiting the fitness of generalists in any of the alternative hosts or because evolution proceeds faster with narrower niches. Here we review experiments showing that virus adaptation to a specific host is often coupled with fitness losses in alternative ones. In most instances, mutations beneficial in one host are detrimental in another. This antagonistic pleiotropy should limit the range of adaptation and promote the evolution of specialization. However, when hosts fluctuate in time or space, selective pressures are different and generalist viruses may evolve as well. PMID:19572052

  3. Analysis of the Aspergillus fumigatus Biofilm Extracellular Matrix by Solid-State Nuclear Magnetic Resonance Spectroscopy

    PubMed Central

    Reichhardt, Courtney; Ferreira, Jose A. G.; Joubert, Lydia-Marie; Clemons, Karl V.; Stevens, David A.

    2015-01-01

    Aspergillus fumigatus is commonly responsible for lethal fungal infections among immunosuppressed individuals. A. fumigatus forms biofilm communities that are of increasing biomedical interest due to the association of biofilms with chronic infections and their increased resistance to antifungal agents and host immune factors. Understanding the composition of microbial biofilms and the extracellular matrix is important to understanding function and, ultimately, to developing strategies to inhibit biofilm formation. We implemented a solid-state nuclear magnetic resonance (NMR) approach to define compositional parameters of the A. fumigatus extracellular matrix (ECM) when biofilms are formed in RPMI 1640 nutrient medium. Whole biofilm and isolated matrix networks were also characterized by electron microscopy, and matrix proteins were identified through protein gel analysis. The 13C NMR results defined and quantified the carbon contributions in the insoluble ECM, including carbonyls, aromatic carbons, polysaccharide carbons (anomeric and nonanomerics), aliphatics, etc. Additional 15N and 31P NMR spectra permitted more specific annotation of the carbon pools according to C-N and C-P couplings. Together these data show that the A. fumigatus ECM produced under these growth conditions contains approximately 40% protein, 43% polysaccharide, 3% aromatic-containing components, and up to 14% lipid. These fundamental chemical parameters are needed to consider the relationships between composition and function in the A. fumigatus ECM and will enable future comparisons with other organisms and with A. fumigatus grown under alternate conditions. PMID:26163318

  4. Microsporidia-Host Interactions

    PubMed Central

    Szumowski, Suzannah C.; Troemel, Emily R.

    2015-01-01

    Microsporidia comprise one of the largest groups of obligate intracellular pathogens and can infect virtually all animals, but host response to these fungal-related microbes has been poorly understood. Several new studies of the host transcriptional response to microsporidia infection have found infection-induced regulation of genes involved in innate immunity, ubiquitylation, metabolism, and hormonal signaling. In addition, microsporidia have recently been shown to exploit host recycling endocytosis for exit from intestinal cells, and to interact with host degradation pathways. Microsporidia infection has also been shown to profoundly affect behavior in insect hosts. Altogether, these and other recent findings are providing much-needed insight into the underlying mechanisms of microsporidia interaction with host animals. PMID:25847674

  5. Glob-Hosts

    Energy Science and Technology Software Center (ESTSC)

    2007-08-31

    The glob-hosts utility manipulates hostlist strings in UNIX shell scripts. Hostlists are a parseable string representatin of list of hosts, which compress nicely when a group of hosts are named with contiguous numeric suffixes. For example, the hosts blue1, blue2, and blue3 can be represented by the hostlist string "blue1, blue2, blue3" or equivalently "blue[1-3]". The globhost utility cn peform the following operations on a hostlist string: count, size, expand, nth, union, minus, intersection, andmore » exclude.« less

  6. Finding Nonoverlapping Substructures of a Sparse Matrix

    SciTech Connect

    Pinar, Ali; Vassilevska, Virginia

    2005-08-11

    Many applications of scientific computing rely on computations on sparse matrices. The design of efficient implementations of sparse matrix kernels is crucial for the overall efficiency of these applications. Due to the high compute-to-memory ratio and irregular memory access patterns, the performance of sparse matrix kernels is often far away from the peak performance on a modern processor. Alternative data structures have been proposed, which split the original matrix A into A{sub d} and A{sub s}, so that A{sub d} contains all dense blocks of a specified size in the matrix, and A{sub s} contains the remaining entries. This enables the use of dense matrix kernels on the entries of A{sub d} producing better memory performance. In this work, we study the problem of finding a maximum number of nonoverlapping dense blocks in a sparse matrix, which is previously not studied in the sparse matrix community. We show that the maximum nonoverlapping dense blocks problem is NP-complete by using a reduction from the maximum independent set problem on cubic planar graphs. We also propose a 2/3-approximation algorithm that runs in linear time in the number of nonzeros in the matrix. This extended abstract focuses on our results for 2x2 dense blocks. However we show that our results can be generalized to arbitrary sized dense blocks, and many other oriented substructures, which can be exploited to improve the memory performance of sparse matrix operations.

  7. Biocompatible 3D Matrix with Antimicrobial Properties.

    PubMed

    Ion, Alberto; Andronescu, Ecaterina; Rădulescu, Dragoș; Rădulescu, Marius; Iordache, Florin; Vasile, Bogdan Ștefan; Surdu, Adrian Vasile; Albu, Madalina Georgiana; Maniu, Horia; Chifiriuc, Mariana Carmen; Grumezescu, Alexandru Mihai; Holban, Alina Maria

    2016-01-01

    The aim of this study was to develop, characterize and assess the biological activity of a new regenerative 3D matrix with antimicrobial properties, based on collagen (COLL), hydroxyapatite (HAp), β-cyclodextrin (β-CD) and usnic acid (UA). The prepared 3D matrix was characterized by Scanning Electron Microscopy (SEM), Fourier Transform Infrared Microscopy (FT-IRM), Transmission Electron Microscopy (TEM), and X-ray Diffraction (XRD). In vitro qualitative and quantitative analyses performed on cultured diploid cells demonstrated that the 3D matrix is biocompatible, allowing the normal development and growth of MG-63 osteoblast-like cells and exhibited an antimicrobial effect, especially on the Staphylococcus aureus strain, explained by the particular higher inhibitory activity of usnic acid (UA) against Gram positive bacterial strains. Our data strongly recommend the obtained 3D matrix to be used as a successful alternative for the fabrication of three dimensional (3D) anti-infective regeneration matrix for bone tissue engineering. PMID:26805790

  8. Amyloid Structures as Biofilm Matrix Scaffolds.

    PubMed

    Taglialegna, Agustina; Lasa, Iñigo; Valle, Jaione

    2016-10-01

    Recent insights into bacterial biofilm matrix structures have induced a paradigm shift toward the recognition of amyloid fibers as common building block structures that confer stability to the exopolysaccharide matrix. Here we describe the functional amyloid systems related to biofilm matrix formation in both Gram-negative and Gram-positive bacteria and recent knowledge regarding the interaction of amyloids with other biofilm matrix components such as extracellular DNA (eDNA) and the host immune system. In addition, we summarize the efforts to identify compounds that target amyloid fibers for therapeutic purposes and recent developments that take advantage of the amyloid structure to engineer amyloid fibers of bacterial biofilm matrices for biotechnological applications. PMID:27185827

  9. Scanning electron image analysis to monitor of implant degradation and host healing following implantation of a drug-eluting bone graft void filler - biomed 2013.

    PubMed

    Davidoff, Sherry N; Lawson, Scott T; Grainger, David W; Brooks, Amanda E

    2013-01-01

    Osteomyelitis is most commonly caused by Staphylococcus aureus and often sourced during orthopedic surgical intervention. Successful treatment or prevention of this bone penetrating infection requires antibiotics be delivered in excess of the minimal inhibitory concentration to prohibit the growth of the causative organism for sufficient duration. Unfortunately, current standard-of-care antibiotic therapies, administered via intravenous or oral delivery, suffer not only from systemic toxicity and low patient compliance but also provide insufficient local concentrations for therapy. To overcome these clinical inadequacies, a synthetic bone graft material was coated with an antibiotic (tobramycin)-releasing polymer (polycaprolactone) matrix to create a polymer-controlled antibiotic- releasing combination therapy for use as a bone void filler in orthopedic surgeries. Even though this local delivery strategy allows antibiotic delivery over a clinically relevant time frame to prevent infection, complete healing requires the host bone to infiltrate and reabsorb the bone void filler, ultimately replacing the defect with healthy tissue. Unfortunately, the same polymer matrix that allows for controlled local antibiotic delivery may also discourage host bone healing. Efficient orthopedic healing requires the rate of polymer degradation to match the rate of host-bone infiltration. Current imaging techniques, such as histological staining and x-ray imaging, are insufficient to simultaneously assess polymer degradation and host bone integration. Alternative techniques relying on backscatter electron detection during scanning electron microscopy (SEM) imaging may allow a visual differentiation between host bone, synthetic bone, and polymer. Analysis of backscattered SEM images was automated using a custom MATLAB program to determine the ratio of bone to polymer based upon the contrast between the bone (white) and polymer (dark grey). By collecting images of the implant over time

  10. A matrix lower bound

    SciTech Connect

    Grcar, Joseph F.

    2002-02-04

    A matrix lower bound is defined that generalizes ideas apparently due to S. Banach and J. von Neumann. The matrix lower bound has a natural interpretation in functional analysis, and it satisfies many of the properties that von Neumann stated for it in a restricted case. Applications for the matrix lower bound are demonstrated in several areas. In linear algebra, the matrix lower bound of a full rank matrix equals the distance to the set of rank-deficient matrices. In numerical analysis, the ratio of the matrix norm to the matrix lower bound is a condition number for all consistent systems of linear equations. In optimization theory, the matrix lower bound suggests an identity for a class of min-max problems. In real analysis, a recursive construction that depends on the matrix lower bound shows that the level sets of continuously differential functions lie asymptotically near those of their tangents.

  11. Cosmic alternatives?

    NASA Astrophysics Data System (ADS)

    Gregory, Ruth

    2009-04-01

    "Cosmologists are often in error but never in doubt." This pithy characterization by the Soviet physicist Lev Landau sums up the raison d'être of Facts and Speculations in Cosmology. Authors Jayant Narlikar and Geoffrey Burbidge are proponents of a "steady state" theory of cosmology, and they argue that the cosmological community has become fixated on a "Big Bang" dogma, suppressing alternative viewpoints. This book very much does what it says on the tin: it sets out what is known in cosmology, and puts forward the authors' point of view on an alternative to the Big Bang.

  12. New Hosts of The Lassa Virus.

    PubMed

    Olayemi, Ayodeji; Cadar, Daniel; Magassouba, N'Faly; Obadare, Adeoba; Kourouma, Fode; Oyeyiola, Akinlabi; Fasogbon, Samuel; Igbokwe, Joseph; Rieger, Toni; Bockholt, Sabrina; Jérôme, Hanna; Schmidt-Chanasit, Jonas; Garigliany, Mutien; Lorenzen, Stephan; Igbahenah, Felix; Fichet, Jean-Nicolas; Ortsega, Daniel; Omilabu, Sunday; Günther, Stephan; Fichet-Calvet, Elisabeth

    2016-01-01

    Lassa virus (LASV) causes a deadly haemorrhagic fever in humans, killing several thousand people in West Africa annually. For 40 years, the Natal multimammate rat, Mastomys natalensis, has been assumed to be the sole host of LASV. We found evidence that LASV is also hosted by other rodent species: the African wood mouse Hylomyscus pamfi in Nigeria, and the Guinea multimammate mouse Mastomys erythroleucus in both Nigeria and Guinea. Virus strains from these animals were isolated in the BSL-4 laboratory and fully sequenced. Phylogenetic analyses of viral genes coding for glycoprotein, nucleoprotein, polymerase and matrix protein show that Lassa strains detected in M. erythroleucus belong to lineages III and IV. The strain from H. pamfi clusters close to lineage I (for S gene) and between II &III (for L gene). Discovery of new rodent hosts has implications for LASV evolution and its spread into new areas within West Africa. PMID:27140942

  13. New Hosts of The Lassa Virus

    PubMed Central

    Olayemi, Ayodeji; Cadar, Daniel; Magassouba, N’Faly; Obadare, Adeoba; Kourouma, Fode; Oyeyiola, Akinlabi; Fasogbon, Samuel; Igbokwe, Joseph; Rieger, Toni; Bockholt, Sabrina; Jérôme, Hanna; Schmidt-Chanasit, Jonas; Garigliany, Mutien; Lorenzen, Stephan; Igbahenah, Felix; Fichet, Jean-Nicolas; Ortsega, Daniel; Omilabu, Sunday; Günther, Stephan; Fichet-Calvet, Elisabeth

    2016-01-01

    Lassa virus (LASV) causes a deadly haemorrhagic fever in humans, killing several thousand people in West Africa annually. For 40 years, the Natal multimammate rat, Mastomys natalensis, has been assumed to be the sole host of LASV. We found evidence that LASV is also hosted by other rodent species: the African wood mouse Hylomyscus pamfi in Nigeria, and the Guinea multimammate mouse Mastomys erythroleucus in both Nigeria and Guinea. Virus strains from these animals were isolated in the BSL-4 laboratory and fully sequenced. Phylogenetic analyses of viral genes coding for glycoprotein, nucleoprotein, polymerase and matrix protein show that Lassa strains detected in M. erythroleucus belong to lineages III and IV. The strain from H. pamfi clusters close to lineage I (for S gene) and between II & III (for L gene). Discovery of new rodent hosts has implications for LASV evolution and its spread into new areas within West Africa. PMID:27140942

  14. Optical properties of matrix confined species

    NASA Astrophysics Data System (ADS)

    Lezhnina, M. M.; Kynast, U. H.

    2010-11-01

    A majority of optically functional materials can be perceived as a liaison between ionic or molecular guests and a more or less rigid host. The guests exhibit an optical function, whereas the host provides suitable space, both of them synergistically complementing each other. The embracement of guests and hosts is often very intimate, as e.g. in typical phosphors, where luminescent ions even become part of the host. While the host-guest terminology usually is not applied to such marriages, the term becomes appropriate, if the host grants some degrees of spatial freedom, yet giving order and structure to its guests. Zeolites, clays and inverse opals are porous materials naturally providing hospitable cavities, channels or other compartments, and at the same time the guests are often demanded to occupy preassigned positions within these, or to structurally adapt to the interior host topology. Whereas zeolites and clays are merely patient providers of guest space, inverse opals, can actively turn the light on and off. The present article summarises and highlights recent experimental evidence, ongoing research and some envisaged merits resulting from the interaction of matrix confined luminescent ions, complexes and molecules with a focus on the optical properties of rare earth based materials.

  15. ALTERNATIVE OXIDANTS

    EPA Science Inventory

    This chapter reports on the efforts of the USEPA to study chloramines, chlorine dioxide and ozone as alternative oxidants/disinfectants to chlorine for the control of disinfection by-rpdocuts (DBPs) in drinking water. It examines the control of DBPs like trihalomethanes and haloa...

  16. Alternative Thinking.

    ERIC Educational Resources Information Center

    Herman, Dan

    1999-01-01

    Explains how advances in diesel and alternative fuels has caused schools to reconsider their use for their bus fleets. Reductions in air pollution emissions, cost-savings developments, and the economies experienced from less downtime and maintenance requirements are explored. (GR)

  17. Alternative Conceptualizations.

    ERIC Educational Resources Information Center

    Borman, Kathryn M., Ed.; O'Reilly, Patricia, Ed.

    1992-01-01

    This theme issue of the serial "Educational Foundations" contains five articles devoted to the topic of "Alternative Conceptualizations" of the foundations of education. In "The Concept of Place in the New Sociology of Education," Paul Theobald examines the notion of place in educational theory and practice. Janice Jipson and Nicholas Paley, in…

  18. Viral pathogen production in a wild grass host driven by host growth and soil nitrogen.

    PubMed

    Whitaker, Briana K; Rúa, Megan A; Mitchell, Charles E

    2015-08-01

    Nutrient limitation is a basic ecological constraint that has received little attention in studies on virus production and disease dynamics. Nutrient availability could directly limit the production of viral nucleic acids and proteins, or alternatively limit host growth and thus indirectly limit metabolic pathways necessary for viral replication. In order to compare direct and indirect effects of nutrient limitation on virus production within hosts, we manipulated soil nitrogen (N) and phosphorus (P) availability in a glasshouse for the wild grass host Bromus hordeaceus and the viral pathogen Barley yellow dwarf virus-PAV. We found that soil N additions increased viral concentrations within host tissues, and the effect was mediated by host growth. Specifically, in statistical models evaluating the roles of host biomass production, leaf N and leaf P, viral production depended most strongly on host biomass, rather than the concentration of either nutrient. Furthermore, at low soil N, larger plants supported greater viral concentrations than smaller ones, whereas at high N, smaller plants supported greater viral concentrations. Our results suggest that enhanced viral productivity under N enrichment is an indirect consequence of nutrient stimulation to host growth rate. Heightened pathogen production in plants has important implications for a world facing increasing rates of nutrient deposition. PMID:25782030

  19. Carbonate fuel cell matrix

    DOEpatents

    Farooque, M.; Yuh, C.Y.

    1996-12-03

    A carbonate fuel cell matrix is described comprising support particles and crack attenuator particles which are made platelet in shape to increase the resistance of the matrix to through cracking. Also disclosed is a matrix having porous crack attenuator particles and a matrix whose crack attenuator particles have a thermal coefficient of expansion which is significantly different from that of the support particles, and a method of making platelet-shaped crack attenuator particles. 8 figs.

  20. Carbonate fuel cell matrix

    DOEpatents

    Farooque, Mohammad; Yuh, Chao-Yi

    1996-01-01

    A carbonate fuel cell matrix comprising support particles and crack attenuator particles which are made platelet in shape to increase the resistance of the matrix to through cracking. Also disclosed is a matrix having porous crack attenuator particles and a matrix whose crack attenuator particles have a thermal coefficient of expansion which is significantly different from that of the support particles, and a method of making platelet-shaped crack attenuator particles.

  1. Matrix differentiation formulas

    NASA Technical Reports Server (NTRS)

    Usikov, D. A.; Tkhabisimov, D. K.

    1983-01-01

    A compact differentiation technique (without using indexes) is developed for scalar functions that depend on complex matrix arguments which are combined by operations of complex conjugation, transposition, addition, multiplication, matrix inversion and taking the direct product. The differentiation apparatus is developed in order to simplify the solution of extremum problems of scalar functions of matrix arguments.

  2. Matrix with Prescribed Eigenvectors

    ERIC Educational Resources Information Center

    Ahmad, Faiz

    2011-01-01

    It is a routine matter for undergraduates to find eigenvalues and eigenvectors of a given matrix. But the converse problem of finding a matrix with prescribed eigenvalues and eigenvectors is rarely discussed in elementary texts on linear algebra. This problem is related to the "spectral" decomposition of a matrix and has important technical…

  3. Alternate fuels

    SciTech Connect

    Ryan, T.W.; Worthen, R.P.

    1981-02-01

    The escalating oil prices and shortages of petroleum based fuels for transportation have made research work on various fuel alternatives, especially for transportation engines, a priority of both the private and public sectors. This book contains 18 papers on this subject. The range of options from the development of completely non-petroleum-based fuels and engines to the use of various non-petroleum gasoline and diesel fuel extenders and improvers are discussed.

  4. Systems and methods for deactivating a matrix converter

    SciTech Connect

    Ransom, Ray M.

    2013-04-02

    Systems and methods are provided for deactivating a matrix conversion module. An electrical system comprises an alternating current (AC) interface, a matrix conversion module coupled to the AC interface, an inductive element coupled between the AC interface and the matrix conversion module, and a control module. The control module is coupled to the matrix conversion module, and in response to a shutdown condition, the control module is configured to operate the matrix conversion module to deactivate the first conversion module when a magnitude of a current through the inductive element is less than a threshold value.

  5. Potential alternative hosts for a powdery mildew on pea

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Powdery mildew of pea (Pisum sativum) is an important disease in the field and in the greenhouse. The most widely documented powdery mildew on pea is Erysiphe pisi, but E. trifolii and E. baeumleri have also been reported. From greenhouse-grown peas, we obtained powdery mildew samples with rDNA ITS ...

  6. Host-to-host encryption using commercial networking products

    SciTech Connect

    Not Available

    1980-10-06

    The report considers three commercial devices in a setting of host-to-host encryption. The basic questions considered are: (1) can this local networking product be modified to provide host-to-host encryption; (2) how could host-to-host encryption be achieved without modifying this local networking product. The HYPERchannel adapter from Network Systems Corporation, the Net/One from Ungermann-Bass, and the Computrol's Megalink product are each be examined. Section 2 discusses the general issues of host-to-host encryption. A generic host-to-host cryptosystem is developed, to be used later in the analysis of the specific products. Section 3 presents in turn the HYPERchannel, Net/One, and Megalink, considering the possibilities of host-to-host encryption with and without product modification. The report's conclusions are summarized in Section 4.

  7. Nanocrystal doped matrixes

    DOEpatents

    Parce, J. Wallace; Bernatis, Paul; Dubrow, Robert; Freeman, William P.; Gamoras, Joel; Kan, Shihai; Meisel, Andreas; Qian, Baixin; Whiteford, Jeffery A.; Ziebarth, Jonathan

    2010-01-12

    Matrixes doped with semiconductor nanocrystals are provided. In certain embodiments, the semiconductor nanocrystals have a size and composition such that they absorb or emit light at particular wavelengths. The nanocrystals can comprise ligands that allow for mixing with various matrix materials, including polymers, such that a minimal portion of light is scattered by the matrixes. The matrixes of the present invention can also be utilized in refractive index matching applications. In other embodiments, semiconductor nanocrystals are embedded within matrixes to form a nanocrystal density gradient, thereby creating an effective refractive index gradient. The matrixes of the present invention can also be used as filters and antireflective coatings on optical devices and as down-converting layers. Processes for producing matrixes comprising semiconductor nanocrystals are also provided. Nanostructures having high quantum efficiency, small size, and/or a narrow size distribution are also described, as are methods of producing indium phosphide nanostructures and core-shell nanostructures with Group II-VI shells.

  8. Asteroseismology and Exoplanet Hosts

    NASA Astrophysics Data System (ADS)

    Huber, Daniel

    2015-08-01

    Asteroseismology is among the most powerful observational tools to determine fundamental properties of stars. Space-based photometry has recently enabled the systematic detection of oscillations in exoplanet host stars, allowing a combination of asteroseismology with transit and radial-velocity measurements to precisely characterize planetary systems. In this talk I will review the latest asteroseismic detections in exoplanet host stars spanning from the main sequence to the red-giant branch, focusing in particular on radii and ages of stars hosting small (sub-Neptune sized) planets discovered by the Kepler mission. I will furthermore discuss applications of asteroseismology to measure spin-orbit inclinations in multiplanet systems, and their implications for formation theories of hot Jupiters. Finally I will give an outlook on asteroseismic studies of exoplanet hosts with current and future space- and ground-based facilities such as K2, SONG, TESS, and PLATO.

  9. Alternative fuels

    NASA Technical Reports Server (NTRS)

    Grobman, J. S.; Butze, H. F.; Friedman, R.; Antoine, A. C.; Reynolds, T. W.

    1977-01-01

    Potential problems related to the use of alternative aviation turbine fuels are discussed and both ongoing and required research into these fuels is described. This discussion is limited to aviation turbine fuels composed of liquid hydrocarbons. The advantages and disadvantages of the various solutions to the problems are summarized. The first solution is to continue to develop the necessary technology at the refinery to produce specification jet fuels regardless of the crude source. The second solution is to minimize energy consumption at the refinery and keep fuel costs down by relaxing specifications.

  10. Alternatives to fluoride in the prevention and treatment of dental erosion.

    PubMed

    Buzalaf, Marília Afonso Rabelo; Magalhães, Ana Carolina; Wiegand, Annette

    2014-01-01

    In recent years, different agents have been discussed as potential alternatives to fluoride in the prevention of dental erosion. These agents are intended to form acid-resistant layers on the surface, to induce repair of eroded lesions by mineral precipitation or to prevent the enzymatic degradation of demineralised collagen. The application of adhesives and/or fissure sealants is considered to be an effective alternative to fluoride, but requires professional application and, depending on the product used, a re-sealing of the surface every several months. Studies testing film-forming products, such as polymers, have suggested the potential effectiveness of some of these approaches, such as chitosan, although further studies are needed to confirm the effectiveness of this approach. Other studies have demonstrated that products designed to deliver calcium and/or phosphate have not been successful at providing a significant anti-erosive effect. In advanced erosive lesions, the demineralised collagenous dentine matrix can be degraded by host enzymes such as matrix metalloproteinases (MMPs). As well as fluorides, epigallocatechin gallate and chlorhexidine have been identified as effective MMP inhibitors, with the potential to reduce the progression of dentine erosion. While fluoride compounds have been shown to have an anti-erosive potential, particularly those containing tin, alternative approaches that provide even greater protective capacity still need to be developed and proven to be effective. PMID:24993272

  11. Modifying Matrix Materials to Increase Wetting and Adhesion

    NASA Technical Reports Server (NTRS)

    Zhong, Katie

    2011-01-01

    In an alternative approach to increasing the degrees of wetting and adhesion between the fiber and matrix components of organic-fiber/polymer matrix composite materials, the matrix resins are modified. Heretofore, it has been common practice to modify the fibers rather than the matrices: The fibers are modified by chemical and/or physical surface treatments prior to combining the fibers with matrix resins - an approach that entails considerable expense and usually results in degradation (typically, weakening) of fibers. The alternative approach of modifying the matrix resins does not entail degradation of fibers, and affords opportunities for improving the mechanical properties of the fiber composites. The alternative approach is more cost-effective, not only because it eliminates expensive fiber-surface treatments but also because it does not entail changes in procedures for manufacturing conventional composite-material structures. The alternative approach is best described by citing an example of its application to a composite of ultra-high-molecular- weight polyethylene (UHMWPE) fibers in an epoxy matrix. The epoxy matrix was modified to a chemically reactive, polarized epoxy nano-matrix to increase the degrees of wetting and adhesion between the fibers and the matrix. The modification was effected by incorporating a small proportion (0.3 weight percent) of reactive graphitic nanofibers produced from functionalized nanofibers into the epoxy matrix resin prior to combining the resin with the UHMWPE fibers. The resulting increase in fiber/matrix adhesion manifested itself in several test results, notably including an increase of 25 percent in the maximum fiber pullout force and an increase of 60-65 percent in fiber pullout energy. In addition, it was conjectured that the functionalized nanofibers became involved in the cross linking reaction of the epoxy resin, with resultant enhancement of the mechanical properties and lower viscosity of the matrix.

  12. Development of a Biological Scaffold Engineered Using the Extracellular Matrix Secreted by Skeletal Muscle Cells

    PubMed Central

    Hurd, Shiloh; Bhati, Nadia; Walker, Addison; Kasukonis, Ben; Wolchok, Jeffrey C.

    2015-01-01

    The performance of implantable biomaterials derived from decellularized tissue, including encouraging results with skeletal muscle, suggests that the extracellular matrix (ECM) derived from native tissue has promising regenerative potential. Yet, the supply of biomaterials derived from donated tissue will always be limited, which is why the in-vitro fabrication of ECM biomaterials that mimic the properties of tissue is an attractive alternative. Towards this end, our group has utilized a novel method to collect the ECM that skeletal muscle myoblasts secrete and form it into implantable scaffolds. The cell derived ECM contained several matrix constituents, including collagen and fibronectin that were also identified within skeletal muscle samples. The ECM was organized into a porous network that could be formed with the elongated and aligned architecture observed within muscle samples. The ECM material supported the attachment and in-vitro proliferation of cells, suggesting effectiveness for cell transplantation, and was well tolerated by the host when examined in-vivo. The results suggest that the ECM collection approach can be used to produce biomaterials with compositions and structures that are similar to muscle samples, and while the physical properties may not yet match muscle values, the in-vitro and in-vivo results indicate it may be a suitable first generation alternative to tissue derived biomaterials. PMID:25725550

  13. Host switching in cowbird brood parasites: how often does it occur?

    PubMed

    Domínguez, M; de la Colina, M A; Di Giacomo, A G; Reboreda, J C; Mahler, B

    2015-06-01

    Avian obligate brood parasites lay their eggs in nests of host species, which provide all parental care. Brood parasites may be host specialists, if they use one or a few host species, or host generalists, if they parasitize many hosts. Within the latter, strains of host-specific females might coexist. Although females preferentially parasitize one host, they may occasionally successfully parasitize the nest of another species. These host switching events allow the colonization of new hosts and the expansion of brood parasites into new areas. In this study, we analyse host switching in two parasitic cowbirds, the specialist screaming cowbird (Molothrus rufoaxillaris) and the generalist shiny cowbird (M. bonariensis), and compare the frequency of host switches between these species with different parasitism strategies. Contrary to expected, host switches did not occur more frequently in the generalist than in the specialist brood parasite. We also found that migration between hosts was asymmetrical in most cases and host switches towards one host were more recurrent than backwards, thus differing among hosts within the same species. This might depend on a combination of factors including the rate at which females lay eggs in nests of alternative hosts, fledging success of the chicks in this new host and their subsequent success in parasitizing it. PMID:25903962

  14. Association and Host Selectivity in Multi-Host Pathogens

    PubMed Central

    Malpica, José M.; Sacristán, Soledad; Fraile, Aurora; García-Arenal, Fernando

    2006-01-01

    The distribution of multi-host pathogens over their host range conditions their population dynamics and structure. Also, host co-infection by different pathogens may have important consequences for the evolution of hosts and pathogens, and host-pathogen co-evolution. Hence it is of interest to know if the distribution of pathogens over their host range is random, or if there are associations between hosts and pathogens, or between pathogens sharing a host. To analyse these issues we propose indices for the observed patterns of host infection by pathogens, and for the observed patterns of co-infection, and tests to analyse if these patterns conform to randomness or reflect associations. Applying these tests to the prevalence of five plant viruses on 21 wild plant species evidenced host-virus associations: most hosts and viruses were selective for viruses and hosts, respectively. Interestingly, the more host-selective viruses were the more prevalent ones, suggesting that host specialisation is a successful strategy for multi-host pathogens. Analyses also showed that viruses tended to associate positively in co-infected hosts. The developed indices and tests provide the tools to analyse how strong and common are these associations among different groups of pathogens, which will help to understand and model the population biology of multi-host pathogens. PMID:17183670

  15. Biofilm Matrix Proteins

    PubMed Central

    Fong, Jiunn N. C.; Yildiz, Fitnat H.

    2015-01-01

    Proteinaceous components of the biofilm matrix include secreted extracellular proteins, cell surface adhesins and protein subunits of cell appendages such as flagella and pili. Biofilm matrix proteins play diverse roles in biofilm formation and dissolution. They are involved in attaching cells to surfaces, stabilizing the biofilm matrix via interactions with exopolysaccharide and nucleic acid components, developing three-dimensional biofilm architectures, and dissolving biofilm matrix via enzymatic degradation of polysaccharides, proteins, and nucleic acids. In this chapter, we will review functions of matrix proteins in a selected set of microorganisms, studies of the matrix proteomes of Vibrio cholerae and Pseudomonas aeruginosa, and roles of outer membrane vesicles and of nucleoid-binding proteins in biofilm formation. PMID:26104709

  16. Alternative technologies

    SciTech Connect

    Corum, L.

    1988-11-01

    We want to get untreated waste out of our landfills, and to do this we want to entice technologies into our state, preferably in the source reduction mode. This is a thumbnail description of the purpose of the Alternative Technologies section (ATS) of the California Department of Health Services (DHS). This paper reports on the ATS program which was initially conceived in recognition that California's relatively strict environmental regulations might be scaring off businesses possessing technologies with the potential to reduce the state's toxic wastes. There are also a lot of great inventors out there and one thing they don't know how to do is move technology into the marketplace. It was hoped that ATS would help shape technologies and move them into appropriate market niches.

  17. Automatic switching matrix

    DOEpatents

    Schlecht, Martin F.; Kassakian, John G.; Caloggero, Anthony J.; Rhodes, Bruce; Otten, David; Rasmussen, Neil

    1982-01-01

    An automatic switching matrix that includes an apertured matrix board containing a matrix of wires that can be interconnected at each aperture. Each aperture has associated therewith a conductive pin which, when fully inserted into the associated aperture, effects electrical connection between the wires within that particular aperture. Means is provided for automatically inserting the pins in a determined pattern and for removing all the pins to permit other interconnecting patterns.

  18. Parasite host range and the evolution of host resistance.

    PubMed

    Gorter, F A; Hall, A R; Buckling, A; Scanlan, P D

    2015-05-01

    Parasite host range plays a pivotal role in the evolution and ecology of hosts and the emergence of infectious disease. Although the factors that promote host range and the epidemiological consequences of variation in host range are relatively well characterized, the effect of parasite host range on host resistance evolution is less well understood. In this study, we tested the impact of parasite host range on host resistance evolution. To do so, we used the host bacterium Pseudomonas fluorescens SBW25 and a diverse suite of coevolved viral parasites (lytic bacteriophage Φ2) with variable host ranges (defined here as the number of host genotypes that can be infected) as our experimental model organisms. Our results show that resistance evolution to coevolved phages occurred at a much lower rate than to ancestral phage (approximately 50% vs. 100%), but the host range of coevolved phages did not influence the likelihood of resistance evolution. We also show that the host range of both single parasites and populations of parasites does not affect the breadth of the resulting resistance range in a naïve host but that hosts that evolve resistance to single parasites are more likely to resist other (genetically) more closely related parasites as a correlated response. These findings have important implications for our understanding of resistance evolution in natural populations of bacteria and viruses and other host-parasite combinations with similar underlying infection genetics, as well as the development of phage therapy. PMID:25851735

  19. NASA HOST project overview

    NASA Technical Reports Server (NTRS)

    Sokolowski, Daniel E.

    1989-01-01

    NASA's Hot Section Technology (HOST) program has developed improved analytical models for the aerothermal environment, thermomechanical loading, material behavior, structural response, and service life of aircraft gas turbine engines' hot section components. These models, in conjunction with sophisticated computer codes, can be used in design analyses of critical combustor and turbine elements. Toward these ends, efforts were undertaken in instrumentation, combustion, turbine heat transfer, structural analysis, fatigue-fracture, and surface protection. Attention is presently given to the organization of HOST activities and their specific subject matter.

  20. Matrix cracking in ceramic-matrix composites

    SciTech Connect

    Danchaivijit, S.; Shetty, D.K. . Dept. of Materials Science and Engineering)

    1993-10-01

    Matrix cracking in ceramic-matrix composites with unbonded frictional interface has been studied using fracture mechanics theory. The critical stress for extension of a fiber-bridged crack has been analyzed using the stress-intensity approach. The analysis uses a new shear-lag formulation of the crack-closure traction applied by the bridging fibers based on the assumption of a constant sliding friction stress over the sliding length of the fiber-matrix interface. The new formulation satisfies two required limiting conditions: (a) when the stress in the bridging fiber approaches the far-field applied stress, the crack-opening displacement approaches a steady-state upper limit that is in agreement with the previous formulations; and (b) in the limit of zero crack opening, the stress in the bridging fiber approaches the far-field fiber stress. This lower limit of the bridging stress is distinctly different from the previous formulations. For all other conditions, the closure traction is a function of the far-field applied stress in addition to the local crack-opening displacement, the interfacial sliding friction stress, and the material properties. Numerical calculations using the stress-intensity approach indicate that the critical stress for crack extension decreases with increasing crack length and approaches a constant steady-state value for large cracks. The steady-state matrix-cracking stress agrees with a steady-state energy balance analysis applied to the continuum model, but it is slightly less than the matrix-cracking stress predicted by such theories of steady-state cracking as that of Aveston, Cooper, and Kelly. The origin of this difference and a method for reconciliation of the two theoretical approaches are discussed.

  1. Host age modulates within-host parasite competition.

    PubMed

    Izhar, Rony; Routtu, Jarkko; Ben-Ami, Frida

    2015-05-01

    In many host populations, one of the most striking differences among hosts is their age. While parasite prevalence differences in relation to host age are well known, little is known on how host age impacts ecological and evolutionary dynamics of diseases. Using two clones of the water flea Daphnia magna and two clones of its bacterial parasite Pasteuria ramosa, we examined how host age at exposure influences within-host parasite competition and virulence. We found that multiply-exposed hosts were more susceptible to infection and suffered higher mortality than singly-exposed hosts. Hosts oldest at exposure were least often infected and vice versa. Furthermore, we found that in young multiply-exposed hosts competition was weak, allowing coexistence and transmission of both parasite clones, whereas in older multiply-exposed hosts competitive exclusion was observed. Thus, age-dependent parasite exposure and host demography (age structure) could together play an important role in mediating parasite evolution. At the individual level, our results demonstrate a previously unnoticed interaction of the host's immune system with host age, suggesting that the specificity of immune function changes as hosts mature. Therefore, evolutionary models of parasite virulence might benefit from incorporating age-dependent epidemiological parameters. PMID:25994010

  2. Transfer function matrix

    NASA Technical Reports Server (NTRS)

    Seraji, H.

    1987-01-01

    Given a multivariable system, it is proved that the numerator matrix N(s) of the transfer function evaluated at any system pole either has unity rank or is a null matrix. It is also shown that N(s) evaluated at any transmission zero of the system has rank deficiency. Examples are given for illustration.

  3. MATRIX AND VECTOR SERVICES

    Energy Science and Technology Software Center (ESTSC)

    2001-10-18

    PETRA V2 provides matrix and vector services and the ability construct, query, and use matrix and vector objects that are used and computed by TRILINOS solvers. It provides all basic matr5ix and vector operations for solvers in TRILINOS.

  4. Matrix metalloproteinases and epileptogenesis.

    PubMed

    Ikonomidou, Chrysanthy

    2014-12-01

    Matrix metalloproteinases are vital drivers of synaptic remodeling in health and disease. It is suggested that at early stages of epileptogenesis, inhibition of matrix metalloproteinases may help ameliorate cell death, aberrant network rewiring, and neuroinflammation and prevent development of epilepsy. PMID:26567100

  5. Grassmann matrix quantum mechanics

    NASA Astrophysics Data System (ADS)

    Anninos, Dionysios; Denef, Frederik; Monten, Ruben

    2016-04-01

    We explore quantum mechanical theories whose fundamental degrees of freedom are rectangular matrices with Grassmann valued matrix elements. We study particular models where the low energy sector can be described in terms of a bosonic Hermitian matrix quantum mechanics. We describe the classical curved phase space that emerges in the low energy sector. The phase space lives on a compact Kähler manifold parameterized by a complex matrix, of the type discovered some time ago by Berezin. The emergence of a semiclassical bosonic matrix quantum mechanics at low energies requires that the original Grassmann matrices be in the long rectangular limit. We discuss possible holographic interpretations of such matrix models which, by construction, are endowed with a finite dimensional Hilbert space.

  6. Time rate collision matrix

    SciTech Connect

    Stoenescu, M.L.; Smith, T.M.

    1980-02-01

    The collision integral terms in Boltzmann equation are reformulated numerically leading to the substitution of the multiple integrals with a multiplicative matrix of the two colliding species velocity distribution functions which varies with the differential collision cross section. A matrix of lower rank may be constructed when one of the distribution functions is specified, in which case the matrix elements represent kinetic transition probabilities in the velocity space and the multiplication of the time rate collision matrix with the unknown velocity distribution function expresses the time rate of change of the distribution. The collision matrix may be used to describe the time evolution of systems in nonequilibrium conditions, to evaluate the rate of momentum and energy transfer between given species, or to generate validity criteria for linearized kinetic equations.

  7. Alternative Splice in Alternative Lice.

    PubMed

    Tovar-Corona, Jaime M; Castillo-Morales, Atahualpa; Chen, Lu; Olds, Brett P; Clark, John M; Reynolds, Stuart E; Pittendrigh, Barry R; Feil, Edward J; Urrutia, Araxi O

    2015-10-01

    Genomic and transcriptomics analyses have revealed human head and body lice to be almost genetically identical; although con-specific, they nevertheless occupy distinct ecological niches and have differing feeding patterns. Most importantly, while head lice are not known to be vector competent, body lice can transmit three serious bacterial diseases; epidemictyphus, trench fever, and relapsing fever. In order to gain insights into the molecular bases for these differences, we analyzed alternative splicing (AS) using next-generation sequencing data for one strain of head lice and one strain of body lice. We identified a total of 3,598 AS events which were head or body lice specific. Exon skipping AS events were overrepresented among both head and body lice, whereas intron retention events were underrepresented in both. However, both the enrichment of exon skipping and the underrepresentation of intron retention are significantly stronger in body lice compared with head lice. Genes containing body louse-specific AS events were found to be significantly enriched for functions associated with development of the nervous system, salivary gland, trachea, and ovarian follicle cells, as well as regulation of transcription. In contrast, no functional categories were overrepresented among genes with head louse-specific AS events. Together, our results constitute the first evidence for transcript pool differences in head and body lice, providing insights into molecular adaptations that enabled human lice to adapt to clothing, and representing a powerful illustration of the pivotal role AS can play in functional adaptation. PMID:26169943

  8. Alternative Splice in Alternative Lice

    PubMed Central

    Tovar-Corona, Jaime M.; Castillo-Morales, Atahualpa; Chen, Lu; Olds, Brett P.; Clark, John M.; Reynolds, Stuart E.; Pittendrigh, Barry R.; Feil, Edward J.; Urrutia, Araxi O.

    2015-01-01

    Genomic and transcriptomics analyses have revealed human head and body lice to be almost genetically identical; although con-specific, they nevertheless occupy distinct ecological niches and have differing feeding patterns. Most importantly, while head lice are not known to be vector competent, body lice can transmit three serious bacterial diseases; epidemictyphus, trench fever, and relapsing fever. In order to gain insights into the molecular bases for these differences, we analyzed alternative splicing (AS) using next-generation sequencing data for one strain of head lice and one strain of body lice. We identified a total of 3,598 AS events which were head or body lice specific. Exon skipping AS events were overrepresented among both head and body lice, whereas intron retention events were underrepresented in both. However, both the enrichment of exon skipping and the underrepresentation of intron retention are significantly stronger in body lice compared with head lice. Genes containing body louse-specific AS events were found to be significantly enriched for functions associated with development of the nervous system, salivary gland, trachea, and ovarian follicle cells, as well as regulation of transcription. In contrast, no functional categories were overrepresented among genes with head louse-specific AS events. Together, our results constitute the first evidence for transcript pool differences in head and body lice, providing insights into molecular adaptations that enabled human lice to adapt to clothing, and representing a powerful illustration of the pivotal role AS can play in functional adaptation. PMID:26169943

  9. The role of pathogen shedding in linking within- and between-host pathogen dynamics.

    PubMed

    Barfield, Michael; Orive, Maria E; Holt, Robert D

    2015-12-01

    A model linking within- and between-host pathogen dynamics via pathogen shedding (emission of pathogens throughout the course of infection) is developed, and several aspects of host availability and co-infection are considered. In this model, the rate of pathogen shedding affects both the pathogen population size within a host (also affecting host mortality) and the rate of infection of new hosts. Our goal is to ascertain how the rate of shedding is likely to evolve, and what factors permit coexistence of alternative shedding rates in a pathogen population. For a constant host population size (where an increase in infected hosts necessarily decreases susceptible hosts), important differences arise depending on whether pathogens compete only for susceptible (uninfected) hosts, or whether co-infection allows for competition for infected hosts. With no co-infection, the pathogen type that can persist with the lowest number of susceptible hosts will outcompete any other, which under the assumptions of the model is the pathogen with the highest basic reproduction number. This is often a pathogen with a relatively high shedding rate (s). If within-host competition is allowed, a trade-off develops due to the conflicting effects of shedding on within- and between-host pathogen dynamics, with within-host competition favoring clones with low shedding rates while between-host competition benefits clones with higher shedding rates. With within-host competition for the same host cells, low shedding rate clones should eliminate high-s clones in a co-infected host, if equilibrium is reached. With co-infection, but no within-host competition, pathogen clones still interact by affecting the mortality of co-infected hosts; here, coexistence is more likely. With co-infection, two clones can coexist if one is the superior competitor for uninfected hosts and the other for co-infected hosts. PMID:25958811

  10. Intermetallic bonded ceramic matrix composites

    SciTech Connect

    Plucknett, K.P.; Tiegs, T.N.; Alexander, K.B.; Becher, P.F.; Schneibel, J.H.; Waters, S.B.; Menchhofer, P.A.

    1995-07-01

    A range of carbide and oxide-based cermets have been developed utilizing ductile nickel aluminide (Ni{sub 3}Al) alloy binder phases. Some of these, notably materials based upon tungsten and titanium carbides (WC and TiC respectively), offer potential as alternatives to the cermets which use cobalt binders (i.e. WC/Co). Samples have been prepared by blending commercially available Ni{sub 3}Al alloy powders with the desired ceramic phases, followed by hot-pressing. Alumina (Al{sub 2}O{sub 3}) matrix materials have also been prepared by pressurized molten alloy infiltration. The microstructure, flexure strength and fracture toughness of selected materials are discussed.

  11. Hybrid matrix amplifier

    DOEpatents

    Martens, J.S.; Hietala, V.M.; Plut, T.A.

    1995-01-03

    The present invention comprises a novel matrix amplifier. The matrix amplifier includes an active superconducting power divider (ASPD) having N output ports; N distributed amplifiers each operatively connected to one of the N output ports of the ASPD; and a power combiner having N input ports each operatively connected to one of the N distributed amplifiers. The distributed amplifier can included M stages of amplification by cascading superconducting active devices. The power combiner can include N active elements. The resulting (N[times]M) matrix amplifier can produce signals of high output power, large bandwidth, and low noise. 6 figures.

  12. Hybrid matrix amplifier

    DOEpatents

    Martens, Jon S.; Hietala, Vincent M.; Plut, Thomas A.

    1995-01-01

    The present invention comprises a novel matrix amplifier. The matrix amplifier includes an active superconducting power divider (ASPD) having N output ports; N distributed amplifiers each operatively connected to one of the N output ports of the ASPD; and a power combiner having N input ports each operatively connected to one of the N distributed amplifiers. The distributed amplifier can included M stages of amplification by cascading superconducting active devices. The power combiner can include N active elements. The resulting (N.times.M) matrix amplifier can produce signals of high output power, large bandwidth, and low noise.

  13. Targeting the bacteria–host interface

    PubMed Central

    Krachler, Anne Marie; Orth, Kim

    2013-01-01

    Bacterial infections are a major cause of morbidity and mortality worldwide and are increasingly problematic to treat due to the rise in antibiotic-resistant strains. It becomes more and more challenging to develop new antimicrobials that are able to withstand the ever-increasing repertoire of bacterial resistance mechanisms. This necessitates the development of alternative approaches to prevent and treat bacterial infections. One of the first steps during bacterial infection is adhesion of the pathogen to host cells. A pathogen’s ability to colonize and invade host tissues strictly depends on this process. Thus, interference with adhesion (anti-adhesion therapy) is an efficient way to prevent or treat bacterial infections. As a basis to present different strategies to interfere with pathogen adhesion, this review briefly introduces general concepts of bacterial attachment to host cells. We further discuss advantages and disadvantages of anti-adhesion treatments and issues that are in need of improvement so as to make anti-adhesion compounds a more broadly applicable alternative to conventional antimicrobials. PMID:23799663

  14. Measurement matrix optimization method based on matrix orthogonal similarity transformation

    NASA Astrophysics Data System (ADS)

    Pan, Jinfeng

    2016-05-01

    Optimization of the measurement matrix is one of the important research aspects of compressive sensing theory. A measurement matrix optimization method is presented based on the orthogonal similarity transformation of the information operator's Gram matrix. In terms of the fact that the information operator's Gram matrix is a singular symmetric matrix, a simplified orthogonal similarity transformation is deduced, and thus the simplified diagonal matrix that is orthogonally similar to it is obtained. Then an approximation of the Gram matrix is obtained by letting all the nonzero diagonal entries of the simplified diagonal matrix equal their average value. Thus an optimized measurement matrix can be acquired according to its relationship with the information operator. Results of experiments show that the optimized measurement matrix compared to the random measurement matrix is less coherent with dictionaries. The relative signal recovery error also declines when the proposed measurement matrix is utilized.

  15. Cross-kingdom host shifts of phytomyxid parasites

    PubMed Central

    2014-01-01

    Background Phytomyxids (plasmodiophorids and phagomyxids) are cosmopolitan, obligate biotrophic protist parasites of plants, diatoms, oomycetes and brown algae. Plasmodiophorids are best known as pathogens or vectors for viruses of arable crops (e.g. clubroot in brassicas, powdery potato scab, and rhizomania in sugar beet). Some phytomyxid parasites are of considerable economic and ecologic importance globally, and their hosts include important species in marine and terrestrial environments. However most phytomyxid diversity remains uncharacterised and knowledge of their relationships with host taxa is very fragmentary. Results Our molecular and morphological analyses of phytomyxid isolates–including for the first time oomycete and sea-grass parasites–demonstrate two cross-kingdom host shifts between closely related parasite species: between angiosperms and oomycetes, and from diatoms/brown algae to angiosperms. Switching between such phylogenetically distant hosts is generally unknown in host-dependent eukaryote parasites. We reveal novel plasmodiophorid lineages in soils, suggesting a much higher diversity than previously known, and also present the most comprehensive phytomyxid phylogeny to date. Conclusion Such large-scale host shifts between closely related obligate biotrophic eukaryote parasites is to our knowledge unique to phytomyxids. Phytomyxids may readily adapt to a wide diversity of new hosts because they have retained the ability to covertly infect alternative hosts. A high cryptic diversity and ubiquitous distribution in agricultural and natural habitats implies that in a changing environment phytomyxids could threaten the productivity of key species in marine and terrestrial environments alike via host shift speciation. PMID:24559266

  16. Probiotics-host communication

    PubMed Central

    Thomas, Carissa M

    2010-01-01

    The intestinal microbiota includes a diverse group of functional microorganisms, including candidate probiotics or viable microorganisms that benefit the host. Beneficial effects of probiotics include enhancing intestinal epithelial cell function, protecting against physiologic stress, modulating cytokine secretion profiles, influencing T-lymphocyte populations, and enhancing antibody secretion. Probiotics have demonstrated significant potential as therapeutic options for a variety of diseases, but the mechanisms responsible for these effects remain to be fully elucidated. Accumulating evidence demonstrates that probiotics communicate with the host by modulating key signaling pathways, such as NFκB and MAPK, to either enhance or suppress activation and influence downstream pathways. Beneficial microbes can profoundly alter the physiology of the gastrointestinal tract, and understanding these mechanisms may result in new diagnostic and therapeutic strategies. PMID:20672012

  17. Hosting a Katrina Evacuee.

    NASA Astrophysics Data System (ADS)

    Hoagland, David

    2008-03-01

    No individual or institution anticipated the impact on the academic research community of hurricane Katrina. When Tulane physicist Wayne Reed asked me to host his research group just a day or two after the disaster, with no authorization or understanding of the commitment, I agreed immediately and then pondered implications. Fortunately, colleagues helped in making the commitment real, only the bureaucracy of my public university posing small hindrances. Industry was remarkably generous in providing Reed with significant ``loaner'' equipment, and amazingly, a suite of custom Reed experiments was running within weeks. At the end, the most productive collaborations for Reed seemed not to have been with my group, with its similar research, but to other groups at my institution, particularly the synthetic chemists, who gained access to methods previously unique to Tulane while offering samples previously unique to UMass. Quickly designed projects exploiting this match turned out remarkably productive. Although begun with trepidation, hosting of Reed had huge positive benefits to me and UMass, and I believe, also to Reed and Tulane. Some key lessons for the future: (i) industry has capacity and willingness to help academic research during disruption (ii) commitment of a host institution must be immediate, without a wait for formal approvals or arrangement of special funding -- delay leads only to discouragement, (iii) continuing academic progress of displaced students must come first, and (iv) intellectual synergy rather than overlap should be the basis for seeking a host. Lastly, NSF or other funding agency should consider a program directly addressing the research needs of unexpectedly disrupted academic scientists, and most particularly, graduate students who face greatly extended studies.

  18. Fatty acid-producing hosts

    SciTech Connect

    Pfleger, Brian F; Lennen, Rebecca M

    2013-12-31

    Described are hosts for overproducing a fatty acid product such as a fatty acid. The hosts include an exogenous nucleic acid encoding a thioesterase and, optionally, an exogenous nucleic acid encoding an acetyl-CoA carboxylase, wherein an acyl-CoA synthetase in the hosts are functionally delected. The hosts prefereably include the nucleic acid encoding the thioesterase at an intermediate copy number. The hosts are preferably recominantly stable and growth-competent at 37.degree. C. Methods of producing a fatty acid product comprising culturing such hosts at 37.degree. C. are also described.

  19. Matrix metalloproteinases and other matrix proteinases in relation to cariology: the era of 'dentin degradomics'.

    PubMed

    Tjäderhane, Leo; Buzalaf, Marília Afonso Rabelo; Carrilho, Marcela; Chaussain, Catherine

    2015-01-01

    Dentin organic matrix, with type I collagen as the main component, is exposed after demineralization in dentinal caries, erosion or acidic conditioning during adhesive composite restorative treatment. This exposed matrix is prone to slow hydrolytic degradation by host collagenolytic enzymes, matrix metalloproteinases (MMPs) and cysteine cathepsins. Here we review the recent findings demonstrating that inhibition of salivary or dentin endogenous collagenolytic enzymes may provide preventive means against progression of caries or erosion, just as they have been shown to retain the integrity and improve the longevity of resin composite filling bonding to dentin. This paper also presents the case that the organic matrix in caries-affected dentin may not be preserved as intact as previously considered. In partially demineralized dentin, MMPs and cysteine cathepsins with the ability to cleave off the terminal non-helical ends of collagen molecules (telopeptides) may lead to the gradual loss of intramolecular gap areas. This would seriously compromise the matrix ability for intrafibrillar remineralization, which is considered essential in restoring the dentin's mechanical properties. More detailed data of the enzymes responsible and their detailed function in dentin-destructive conditions may not only help to find new and better preventive means, but better preservation of demineralized dentin collagenous matrix may also facilitate true biological remineralization for the better restoration of tooth structural and mechanical integrity and mechanical properties. PMID:25661522

  20. Metal Matrix Composites

    SciTech Connect

    Hunt, Warren; Herling, Darrell R.

    2004-02-01

    Metal matrix composites have found selected application in areas that can cost-effectively capitalize on improvements in specific stiffness, specific strength, fatigue resistance, wear resistance, and coefficient of thermal expansion. Metal matrix composites comprise a relatively wide range of materials defined by the metal matrix, reinforcement type, and reinforcement geometry. In the area of the matrix, most metallic systems have been explored, including aluminum, beryllium, magnesium, titanium, iron, nickel, cobalt, and silver. However, aluminum is by far the most preferred. For reinforcements, the materials are typically ceramics, which provide a very beneficial combination of stiffness, strength, and relatively low density. Candidate reinforcement materials include SiC, Al2O3, B4C, TiC, TiB2, graphite, and a number of other ceramics. In addition, metallic materials such as tungsten and steel fibers have been considered.

  1. Pesticide-Exposure Matrix

    Cancer.gov

    The "Pesticide-exposure Matrix" was developed to help epidemiologists and other researchers identify the active ingredients to which people were likely exposed when their homes and gardens were treated for pests in past years.

  2. The Hill Interaction Matrix

    ERIC Educational Resources Information Center

    Hill, William Fawcett

    1971-01-01

    Leadership style, group composition, and group development are simultaneously quantified through the use of the matrix. It represents an attempt to objectify the art of group therapy. Comment by Richard C. Rank follows. (Author)

  3. Mountain Pine Beetle Host Selection Between Lodgepole and Ponderosa Pines in the Southern Rocky Mountains.

    PubMed

    West, Daniel R; Briggs, Jennifer S; Jacobi, William R; Negrón, José F

    2016-02-01

    Recent evidence of range expansion and host transition by mountain pine beetle (Dendroctonus ponderosae Hopkins; MPB) has suggested that MPB may not primarily breed in their natal host, but will switch hosts to an alternate tree species. As MPB populations expanded in lodgepole pine forests in the southern Rocky Mountains, we investigated the potential for movement into adjacent ponderosa pine forests. We conducted field and laboratory experiments to evaluate four aspects of MPB population dynamics and host selection behavior in the two hosts: emergence timing, sex ratios, host choice, and reproductive success. We found that peak MPB emergence from both hosts occurred simultaneously between late July and early August, and the sex ratio of emerging beetles did not differ between hosts. In two direct tests of MPB host selection, we identified a strong preference by MPB for ponderosa versus lodgepole pine. At field sites, we captured naturally emerging beetles from both natal hosts in choice arenas containing logs of both species. In the laboratory, we offered sections of bark and phloem from both species to individual insects in bioassays. In both tests, insects infested ponderosa over lodgepole pine at a ratio of almost 2:1, regardless of natal host species. Reproductive success (offspring/female) was similar in colonized logs of both hosts. Overall, our findings suggest that MPB may exhibit equally high rates of infestation and fecundity in an alternate host under favorable conditions. PMID:26546596

  4. Matrix computations in MACSYMA

    NASA Technical Reports Server (NTRS)

    Wang, P. S.

    1977-01-01

    Facilities built into MACSYMA for manipulating matrices with numeric or symbolic entries are described. Computations will be done exactly, keeping symbols as symbols. Topics discussed include how to form a matrix and create other matrices by transforming existing matrices within MACSYMA; arithmetic and other computation with matrices; and user control of computational processes through the use of optional variables. Two algorithms designed for sparse matrices are given. The computing times of several different ways to compute the determinant of a matrix are compared.

  5. A novel color image encryption scheme using alternate chaotic mapping structure

    NASA Astrophysics Data System (ADS)

    Wang, Xingyuan; Zhao, Yuanyuan; Zhang, Huili; Guo, Kang

    2016-07-01

    This paper proposes an color image encryption algorithm using alternate chaotic mapping structure. Initially, we use the R, G and B components to form a matrix. Then one-dimension logistic and two-dimension logistic mapping is used to generate a chaotic matrix, then iterate two chaotic mappings alternately to permute the matrix. For every iteration, XOR operation is adopted to encrypt plain-image matrix, then make further transformation to diffuse the matrix. At last, the encrypted color image is obtained from the confused matrix. Theoretical analysis and experimental results has proved the cryptosystem is secure and practical, and it is suitable for encrypting color images.

  6. Optical coherency matrix tomography

    PubMed Central

    Kagalwala, Kumel H.; Kondakci, H. Esat; Abouraddy, Ayman F.; Saleh, Bahaa E. A.

    2015-01-01

    The coherence of an optical beam having multiple degrees of freedom (DoFs) is described by a coherency matrix G spanning these DoFs. This optical coherency matrix has not been measured in its entirety to date—even in the simplest case of two binary DoFs where G is a 4 × 4 matrix. We establish a methodical yet versatile approach—optical coherency matrix tomography—for reconstructing G that exploits the analogy between this problem in classical optics and that of tomographically reconstructing the density matrix associated with multipartite quantum states in quantum information science. Here G is reconstructed from a minimal set of linearly independent measurements, each a cascade of projective measurements for each DoF. We report the first experimental measurements of the 4 × 4 coherency matrix G associated with an electromagnetic beam in which polarization and a spatial DoF are relevant, ranging from the traditional two-point Young’s double slit to spatial parity and orbital angular momentum modes. PMID:26478452

  7. Dispersal of a defensive symbiont depends on contact between hosts, host health, and host size.

    PubMed

    Hopkins, Skylar R; Boyle, Lindsey J; Belden, Lisa K; Wojdak, Jeremy M

    2015-10-01

    Symbiont dispersal is necessary for the maintenance of defense mutualisms in space and time, and the distribution of symbionts among hosts should be intricately tied to symbiont dispersal behaviors. However, we know surprisingly little about how most defensive symbionts find and choose advantageous hosts or what cues trigger symbionts to disperse from their current hosts. In a series of six experiments, we explored the dispersal ecology of an oligochaete worm (Chaetogaster limnaei) that protects snail hosts from infection by larval trematode parasites. Specifically, we determined the factors that affected net symbiont dispersal from a current "donor" host to a new "receiver" host. Symbionts rarely dispersed unless hosts directly came in contact with one another. However, symbionts overcame their reluctance to disperse across the open environment if the donor host died. When hosts came in direct contact, net symbiont dispersal varied with both host size and trematode infection status, whereas symbiont density did not influence the probability of symbiont dispersal. Together, these experiments show that symbiont dispersal is not a constant, random process, as is often assumed in symbiont dispersal models, but rather the probability of dispersal varies with ecological conditions and among individual hosts. The observed heterogeneity in dispersal rates among hosts may help to explain symbiont aggregation among snail hosts in nature. PMID:25964062

  8. Comparing mechanisms of host manipulation across host and parasite taxa

    USGS Publications Warehouse

    Lafferty, Kevin D.; Shaw, Jenny C.

    2013-01-01

    Parasites affect host behavior in several ways. They can alter activity, microhabitats or both. For trophically transmitted parasites (the focus of our study), decreased activity might impair the ability of hosts to respond to final-host predators, and increased activity and altered microhabitat choice might increase contact rates between hosts and final-host predators. In an analysis of trophically transmitted parasites, more parasite groups altered activity than altered microhabitat choice. Parasites that infected vertebrates were more likely to impair the host’s reaction to predators, whereas parasites that infected invertebrates were more likely to increase the host’s contact with predators. The site of infection might affect how parasites manipulate their hosts. For instance, parasites in the central nervous system seem particularly suited to manipulating host behavior. Manipulative parasites commonly occupy the body cavity, muscles and central nervous systems of their hosts. Acanthocephalans in the data set differed from other taxa in that they occurred exclusively in the body cavity of invertebrates. In addition, they were more likely to alter microhabitat choice than activity. Parasites in the body cavity (across parasite types) were more likely to be associated with increased host contact with predators. Parasites can manipulate the host through energetic drain, but most parasites use more sophisticated means. For instance, parasites target four physiological systems that shape behavior in both invertebrates and vertebrates: neural, endocrine, neuromodulatory and immunomodulatory. The interconnections between these systems make it difficult to isolate specific mechanisms of host behavioral manipulation.

  9. Inferring host-parasite relationships using stable isotopes: implications for disease transmission and host specificity.

    PubMed

    Stapp, Paul; Salkeld, Daniel J

    2009-11-01

    Identifying the roles of different hosts and vectors is a major challenge in the study of the ecology of diseases caused by multi-host pathogens. Intensive field studies suggested that grasshopper mice (Onychomys leucogaster) help spread the bacterium that causes plague (Yersinia pestis) in prairie dog colonies by sharing fleas with prairie dogs (Cynomys ludovicianus); yet conclusive evidence that prairie dog fleas (Oropsylla hirsuta) feed on grasshopper mice is lacking. Using stable nitrogen isotope analysis, we determined that many blood-engorged O. hirsuta collected from wild grasshopper mice apparently contained blood meals of prairie dogs. These results suggest that grasshopper mice may be infected with Y. pestis via mechanisms other than flea feeding, e.g., early phase or mechanical transmission or scavenging carcasses, and raise questions about the ability of grasshopper mice to maintain Y. pestis in prairie dog colonies during years between plague outbreaks. They also indicate that caution may be warranted when inferring feeding relationships based purely on the occurrence of fleas or other haematophagous ectoparasites on hosts. Stable-isotope analysis may complement or provide a useful alternative to immunological or molecular techniques for identifying hosts of cryptically feeding ectoparasites, and for clarifying feeding relationships in studies of host-parasite interactions. PMID:19967881

  10. Allergic host defences.

    PubMed

    Palm, Noah W; Rosenstein, Rachel K; Medzhitov, Ruslan

    2012-04-26

    Allergies are generally thought to be a detrimental outcome of a mistargeted immune response that evolved to provide immunity to macroparasites. Here we present arguments to suggest that allergic immunity has an important role in host defence against noxious environmental substances, including venoms, haematophagous fluids, environmental xenobiotics and irritants. We argue that appropriately targeted allergic reactions are beneficial, although they can become detrimental when excessive. Furthermore, we suggest that allergic hypersensitivity evolved to elicit anticipatory responses and to promote avoidance of suboptimal environments. PMID:22538607

  11. Predicting structure in nonsymmetric sparse matrix factorizations

    SciTech Connect

    Gilbert, J.R.; Ng, E.

    1991-12-31

    Many computations on sparse matrices have a phase that predicts the nonzero structure of the output, followed by a phase that actually performs the numerical computation. We study structure prediction for computations that involve nonsymmetric row and column permutations and nonsymmetric or non-square matrices. Our tools are bipartite graphs, matchings, and alternating paths. Our main new result concerns LU factorization with partial pivoting. We show that if a square matrix A has the strong Hall property (i.e., is fully indecomposable) then an upper bound due to George and Ng on the nonzero structure of L + U is as tight as possible. To show this, we prove a crucial result about alternating paths in strong Hall graphs. The alternating-paths theorem seems to be of independent interest: it can also be used to prove related results about structure prediction for QR factorization that are due to Coleman, Edenbrandt, Gilbert, Hare, Johnson, Olesky, Pothen, and van den Driessche.

  12. Predicting structure in nonsymmetric sparse matrix factorizations

    SciTech Connect

    Gilbert, J.R. ); Ng, E. )

    1991-01-01

    Many computations on sparse matrices have a phase that predicts the nonzero structure of the output, followed by a phase that actually performs the numerical computation. We study structure prediction for computations that involve nonsymmetric row and column permutations and nonsymmetric or non-square matrices. Our tools are bipartite graphs, matchings, and alternating paths. Our main new result concerns LU factorization with partial pivoting. We show that if a square matrix A has the strong Hall property (i.e., is fully indecomposable) then an upper bound due to George and Ng on the nonzero structure of L + U is as tight as possible. To show this, we prove a crucial result about alternating paths in strong Hall graphs. The alternating-paths theorem seems to be of independent interest: it can also be used to prove related results about structure prediction for QR factorization that are due to Coleman, Edenbrandt, Gilbert, Hare, Johnson, Olesky, Pothen, and van den Driessche.

  13. Predicting structure in nonsymmetric sparse matrix factorizations

    SciTech Connect

    Gilbert, J.R. ); Ng, E.G. )

    1992-10-01

    Many computations on sparse matrices have a phase that predicts the nonzero structure of the output, followed by a phase that actually performs the numerical computation. We study structure prediction for computations that involve nonsymmetric row and column permutations and nonsymmetric or non-square matrices. Our tools are bipartite graphs, matchings, and alternating paths. Our main new result concerns LU factorization with partial pivoting. We show that if a square matrix A has the strong Hall property (i.e., is fully indecomposable) then an upper bound due to George and Ng on the nonzero structure of L + U is as tight as possible. To show this, we prove a crucial result about alternating paths in strong Hall graphs. The alternating-paths theorem seems to be of independent interest: it can also be used to prove related results about structure prediction for QR factorization that are due to Coleman, Edenbrandt, Gilbert, Hare, Johnson, Olesky, Pothen, and van den Driessche.

  14. Host Specificity of Bacterial Pathogens

    PubMed Central

    Bäumler, Andreas; Fang, Ferric C.

    2013-01-01

    Most pathogens are able to infect multiple hosts but some are highly adapted to a single-host species. A detailed understanding of the basis of host specificity can provide important insights into molecular pathogenesis, the evolution of pathogenic microbes, and the potential for pathogens to cross the species barrier to infect new hosts. Comparative genomics and the development of humanized mouse models have provided important new tools with which to explore the basis of generalism and specialism. This review will examine host specificity of bacterial pathogens with a focus on generalist and specialist serovars of Salmonella enterica. PMID:24296346

  15. Matrix interdiction problem

    SciTech Connect

    Pan, Feng; Kasiviswanathan, Shiva

    2010-01-01

    In the matrix interdiction problem, a real-valued matrix and an integer k is given. The objective is to remove k columns such that the sum over all rows of the maximum entry in each row is minimized. This combinatorial problem is closely related to bipartite network interdiction problem which can be applied to prioritize the border checkpoints in order to minimize the probability that an adversary can successfully cross the border. After introducing the matrix interdiction problem, we will prove the problem is NP-hard, and even NP-hard to approximate with an additive n{gamma} factor for a fixed constant {gamma}. We also present an algorithm for this problem that achieves a factor of (n-k) mUltiplicative approximation ratio.

  16. Tendon Functional Extracellular Matrix

    PubMed Central

    Screen, H.R.C.; Birk, D.E.; Kadler, K.E.; Ramirez, F; Young, M.F.

    2015-01-01

    This article is one of a series, summarising views expressed at the Orthopaedic Research Society New Frontiers in Tendon Research Conference. This particular article reviews the three workshops held under the “Functional Extracellular Matrix” stream. The workshops focused on the roles of the tendon extracellular matrix, such as performing the mechanical functions of tendon, creating the local cell environment and providing cellular cues. Tendon is a complex network of matrix and cells, and its biological functions are influenced by widely-varying extrinsic and intrinsic factors such as age, nutrition, exercise levels and biomechanics. Consequently, tendon adapts dynamically during development, ageing and injury. The workshop discussions identified research directions associated with understanding cell-matrix interactions to be of prime importance for developing novel strategies to target tendon healing or repair. PMID:25640030

  17. D-Glucose as a modifying agent in gelatin/collagen matrix and reservoir nanoparticles for Calendula officinalis delivery.

    PubMed

    Lam, P-L; Kok, S H-L; Bian, Z-X; Lam, K-H; Tang, J C-O; Lee, K K-H; Gambari, R; Chui, C-H

    2014-05-01

    Gelatin/Collagen-based matrix and reservoir nanoparticles require crosslinkers to stabilize the formed nanosuspensions, considering that physical instability is the main challenge of nanoparticulate systems. The use of crosslinkers improves the physical integrity of nanoformulations under the-host environment. Aldehyde-based fixatives, such as formaldehyde and glutaraldehyde, have been widely applied to the crosslinking process of polymeric nanoparticles. However, their potential toxicity towards human beings has been demonstrated in many previous studies. In order to tackle this problem, D-glucose was used during nanoparticle formation to stabilize the gelatin/collagen-based matrix wall and reservoir wall for the deliveries of Calendula officinalis powder and oil, respectively. In addition, therapeutic selectivity between malignant and normal cells could be observed. The C. officinalis powder loaded nanoparticles significantly strengthened the anti-cancer effect towards human breast adenocarcinoma MCF7 cells and human hepatoma SKHep1 cells when compared with the free powder. On the contrary, the nanoparticles did not show significant cytotoxicity towards normal esophageal epithelial NE3 cells and human skin keratinocyte HaCaT cells. On the basis of these evidences, D-glucose modified gelatin/collagen matrix nanoparticles containing C. officinalis powder might be proposed as a safer alternative vehicle for anti-cancer treatments. PMID:24657927

  18. Complex matrix model duality

    SciTech Connect

    Brown, T. W.

    2011-04-15

    The same complex matrix model calculates both tachyon scattering for the c=1 noncritical string at the self-dual radius and certain correlation functions of operators which preserve half the supersymmetry in N=4 super-Yang-Mills theory. It is dual to another complex matrix model where the couplings of the first model are encoded in the Kontsevich-like variables of the second. The duality between the theories is mirrored by the duality of their Feynman diagrams. Analogously to the Hermitian Kontsevich-Penner model, the correlation functions of the second model can be written as sums over discrete points in subspaces of the moduli space of punctured Riemann surfaces.

  19. Hospitality Occupational Skills Training Cooperative. Project HOST Curriculum Guide.

    ERIC Educational Resources Information Center

    Northwest Educational Cooperative, Des Plaines, IL.

    This curriculum guide provides instructional materials for an 8-week training program, entitled Hospitality Occupational Skills Training (HOST) Cooperative. It offers an alternative skills training program to meet the needs of disadvantaged, minority populations and of employers who must recruit more highly skilled workers from those populations.…

  20. Matrixed business support comparison study.

    SciTech Connect

    Parsons, Josh D.

    2004-11-01

    The Matrixed Business Support Comparison Study reviewed the current matrixed Chief Financial Officer (CFO) division staff models at Sandia National Laboratories. There were two primary drivers of this analysis: (1) the increasing number of financial staff matrixed to mission customers and (2) the desire to further understand the matrix process and the opportunities and challenges it creates.

  1. Host range, host specificity and hypothesized host shift events among viruses of lower vertebrates

    PubMed Central

    2011-01-01

    The successful replication of a viral agent in a host is a complex process that often leads to a species specificity of the virus and can make interspecies transmission difficult. Despite this difficulty, natural host switch seems to have been frequent among viruses of lower vertebrates, especially fish viruses, since there are several viruses known to be able to infect a wide range of species. In the present review we will focus on well documented reports of broad host range, variations in host specificity, and host shift events hypothesized for viruses within the genera Ranavirus, Novirhabdovirus, Betanodavirus, Isavirus, and some herpesvirus. PMID:21592358

  2. Ceramic Hosts for Fission Products Immobilization

    SciTech Connect

    Peter C Kong

    2010-07-01

    Natural spinel, perovskite and zirconolite rank among the most leach resistant of mineral forms. They also have a strong affinity for a large number of other elements and including actinides. Specimens of natural perovskite and zirconolite were radioisotope dated and found to have survived at least 2 billion years of natural process while still remain their loading of uranium and thorium . Developers of the Synroc waste form recognized and exploited the capability of these minerals to securely immobilize TRU elements in high-level waste . However, the Synroc process requires a relatively uniform input and hot pressing equipment to produce the waste form. It is desirable to develop alternative approaches to fabricate these durable waste forms to immobilize the radioactive elements. One approach is using a high temperature process to synthesize these mineral host phases to incorporate the fission products in their crystalline structures. These mineral assemblages with immobilized fission products are then isolated in a durable high temperature glass for periods measured on a geologic time scale. This is a long term research concept and will begin with the laboratory synthesis of the pure spinel (MgAl2O4), perovskite (CaTiO3) and zirconolite (CaZrTi2O7) from their constituent oxides. High temperature furnace and/or thermal plasma will be used for the synthesis of these ceramic host phases. Nonradioactive strontium oxide will be doped into these ceramic phases to investigate the development of substitutional phases such as Mg1-xSrxAl2O4, Ca1-xSrxTiO3 and Ca1-xSrxZrTi2O7. X-ray diffraction will be used to establish the crystalline structures of the pure ceramic hosts and the substitution phases. Scanning electron microscopy and energy dispersive X-ray analysis (SEM-EDX) will be performed for product morphology and fission product surrogates distribution in the crystalline hosts. The range of strontium doping is planned to reach the full substitution of the divalent

  3. Matrix Synthesis and Characterization

    NASA Technical Reports Server (NTRS)

    1984-01-01

    The role of NASA in the area of composite material synthesis; evaluation techniques; prediction analysis techniques; solvent-resistant tough composite matrix; resistance to paint strippers; acceptable processing temperature and pressure for thermoplastics; and the role of computer modeling and fiber interface improvement were discussed.

  4. The Acrosomal Matrix.

    PubMed

    Foster, James A; Gerton, George L

    2016-01-01

    The acrosome, a single exocytotic vesicle on the head of sperm, has an essential role in fertilization, but the exact mechanisms by which it facilitates sperm-egg interactions remain unresolved. The acrosome contains dozens of secretory proteins that are packaged into the forming structure during spermatogenesis; many of these proteins are localized into specific topographical areas of the acrosome, while others are more diffusely distributed. Acrosomal proteins can also be biochemically classified as components of the acrosomal matrix, a large, relatively insoluble complex, or as soluble proteins. This review focuses on recent findings using genetically modified mice (gene knockouts and transgenic "green acrosome" mice) to study the effects of eliminating acrosomal matrix-associated proteins on sperm structure and function. Some gene knockouts produce infertile phenotypes with obviously missing, specific activities that affect acrosome biogenesis during spermatogenesis or interfere with acrosome function in mature sperm. Mutations that delete some components produce fertile phenotypes with subtler effects that provide useful insights into acrosomal matrix function in fertilization. In general, these studies enable the reassessment of paradigms to explain acrosome formation and function and provide novel, objective insights into the roles of acrosomal matrix proteins in fertilization. The use of genetically engineered mouse models has yielded new mechanistic information that complements recent, important in vivo imaging studies. PMID:27194348

  5. Matrix Embedded Organic Synthesis

    NASA Astrophysics Data System (ADS)

    Kamakolanu, U. G.; Freund, F. T.

    2016-05-01

    In the matrix of minerals such as olivine, a redox reaction of the low-z elements occurs. Oxygen is oxidized to the peroxy state while the low-Z-elements become chemically reduced. We assign them a formula [CxHyOzNiSj]n– and call them proto-organics.

  6. Constructing the matrix

    NASA Astrophysics Data System (ADS)

    Elliott, John

    2012-09-01

    As part of our 'toolkit' for analysing an extraterrestrial signal, the facility for calculating structural affinity to known phenomena must be part of our core capabilities. Without such a resource, we risk compromising our potential for detection and decipherment or at least causing significant delay in the process. To create such a repository for assessing structural affinity, all known systems (language parameters) need to be structurally analysed to 'place' their 'system' within a relational communication matrix. This will need to include all known variants of language structure, whether 'living' (in current use) or ancient; this must also include endeavours to incorporate yet undeciphered scripts and non-human communication, to provide as complete a picture as possible. In creating such a relational matrix, post-detection decipherment will be assisted by a structural 'map' that will have the potential for 'placing' an alien communication with its nearest known 'neighbour', to assist subsequent categorisation of basic parameters as a precursor to decipherment. 'Universal' attributes and behavioural characteristics of known communication structure will form a range of templates (Elliott, 2001 [1] and Elliott et al., 2002 [2]), to support and optimise our attempt at categorising and deciphering the content of an extraterrestrial signal. Detection of the hierarchical layers, which comprise intelligent, complex communication, will then form a matrix of calculations that will ultimately score affinity through a relational matrix of structural comparison. In this paper we develop the rationales and demonstrate functionality with initial test results.

  7. Fungal sensing of host environment.

    PubMed

    Braunsdorf, C; Mailänder-Sánchez, D; Schaller, M

    2016-09-01

    To survive inside a host, fungi have to adapt to a changing and often hostile environment and therefore need the ability to recognize what is going on around them. To adapt to different host niches, they need to sense external conditions such as temperature, pH and to recognize specific host factors. The ability to respond to physiological changes inside the host, independent of being in a commensal, pathogenic or even symbiotic context, implicates mechanisms for sensing of specific host factors. Because the cell wall is constantly in contact with the surrounding, fungi express receptors on the surface of their cell wall, such as pheromone receptors, which have important roles, besides mediating chemotropism for mating. We are not restricting the discussion to the human host because the receptors and mechanisms used by different fungal species to sense their environment are often similar even for plant pathogens. Furthermore, the natural habitat of opportunistic pathogenic fungi with the potential to cause infection in a human host is in soil and on plants. While the hosts' mechanisms of sensing fungal pathogens have been addressed in the literature, the focus of this review is to fill the gap, giving an overview on fungal sensing of a host-(ile) environment. Expanding our knowledge on host-fungal interactions is extremely important to prevent and treat diseases of pathogenic fungi, which are important issues in human health and agriculture but also to understand the delicate balance of fungal symbionts in our ecosystem. PMID:27155351

  8. Lack of Host Specialization on Winter Annual Grasses in the Fungal Seed Bank Pathogen Pyrenophora semeniperda.

    PubMed

    Beckstead, Julie; Meyer, Susan E; Ishizuka, Toby S; McEvoy, Kelsey M; Coleman, Craig E

    2016-01-01

    Generalist plant pathogens may have wide host ranges, but many exhibit varying degrees of host specialization, with multiple pathogen races that have narrower host ranges. These races are often genetically distinct, with each race causing highest disease incidence on its host of origin. We examined host specialization in the seed pathogen Pyrenophora semeniperda by reciprocally inoculating pathogen strains from Bromus tectorum and from four other winter annual grass weeds (Bromus diandrus, Bromus rubens, Bromus arvensis and Taeniatherum caput-medusae) onto dormant seeds of B. tectorum and each alternate host. We found that host species varied in resistance and pathogen strains varied in aggressiveness, but there was no evidence for host specialization. Most variation in aggressiveness was among strains within populations and was expressed similarly on both hosts, resulting in a positive correlation between strain-level disease incidence on B. tectorum and on the alternate host. In spite of this lack of host specialization, we detected weak but significant population genetic structure as a function of host species using two neutral marker systems that yielded similar results. This genetic structure is most likely due to founder effects, as the pathogen is known to be dispersed with host seeds. All host species were highly susceptible to their own pathogen races. Tolerance to infection (i.e., the ability to germinate even when infected and thereby avoid seed mortality) increased as a function of seed germination rate, which in turn increased as dormancy was lost. Pyrenophora semeniperda apparently does not require host specialization to fully exploit these winter annual grass species, which share many life history features that make them ideal hosts for this pathogen. PMID:26950931

  9. Lack of Host Specialization on Winter Annual Grasses in the Fungal Seed Bank Pathogen Pyrenophora semeniperda

    PubMed Central

    Beckstead, Julie; Meyer, Susan E.; Ishizuka, Toby S.; McEvoy, Kelsey M.; Coleman, Craig E.

    2016-01-01

    Generalist plant pathogens may have wide host ranges, but many exhibit varying degrees of host specialization, with multiple pathogen races that have narrower host ranges. These races are often genetically distinct, with each race causing highest disease incidence on its host of origin. We examined host specialization in the seed pathogen Pyrenophora semeniperda by reciprocally inoculating pathogen strains from Bromus tectorum and from four other winter annual grass weeds (Bromus diandrus, Bromus rubens, Bromus arvensis and Taeniatherum caput-medusae) onto dormant seeds of B. tectorum and each alternate host. We found that host species varied in resistance and pathogen strains varied in aggressiveness, but there was no evidence for host specialization. Most variation in aggressiveness was among strains within populations and was expressed similarly on both hosts, resulting in a positive correlation between strain-level disease incidence on B. tectorum and on the alternate host. In spite of this lack of host specialization, we detected weak but significant population genetic structure as a function of host species using two neutral marker systems that yielded similar results. This genetic structure is most likely due to founder effects, as the pathogen is known to be dispersed with host seeds. All host species were highly susceptible to their own pathogen races. Tolerance to infection (i.e., the ability to germinate even when infected and thereby avoid seed mortality) increased as a function of seed germination rate, which in turn increased as dormancy was lost. Pyrenophora semeniperda apparently does not require host specialization to fully exploit these winter annual grass species, which share many life history features that make them ideal hosts for this pathogen. PMID:26950931

  10. A Fungal Endosymbiont Affects Host Plant Recruitment Through Seed- and Litter-mediated Mechanisms

    Technology Transfer Automated Retrieval System (TEKTRAN)

    1. Many grass species are associated with maternally transmitted fungal endophytes. Increasing evidence shows that endophytes enhance host plant success under varied conditions, yet studies have rarely considered alternative mechanisms whereby these mutualistic symbionts may affect regeneration from...