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Search Results: 1 - 10 of 9963 matches for " Frank Ramberg "
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Culex quinquefasciatus (Diptera: Culicidae) as a potential West Nile virus vector in Tucson, Arizona: Blood meal analysis indicates feeding on both humans and birds
Margaret Zinser,Frank Ramberg,Elizabeth Willott
Journal of Insect Science , 2004,
Abstract: Most reports from the United States suggest Culex quinquefasciatus mosquitoes feed minimally on humans. Given the abundance of C. quinquefasciatus in residential Tucson and parts of metropolitan Phoenix, and the arrival of West Nile virus to this area, discovering the blood meal hosts of the local population is important. Using a sandwich ELISA technique, the local C. quinquefasciatus were found to feed on both humans and birds. This suggests they should be considered potential West Nile virus vectors.
Ecdysteroids and oocyte development in the black fly Simulium vittatum
Rafael Noriega, Frank B Ramberg, Henry H Hagedorn
BMC Developmental Biology , 2002, DOI: 10.1186/1471-213x-2-6
Abstract: Oocyte growth was nearly linear between adult eclosion and was complete by 72 hours at 21°C. The oocyte became opaque at 14 hours after eclosion indicating the initiation of protein yolk deposition. The accumulation of vitellogenin was measured using SDS-PAGE. The density of the yolk protein bands at about 200 and 65 kDa increased during the first and second days after eclosion. The amount of protein in the 200 kDa band of vitellogenin, determined using densitometry, rapidly increased between 12 and 25 hours after eclosion. Ecdysteroid levels were measured using a competitive ELISA. Ecdysteroid levels increased rapidly and subsequently declined during the first day after eclosion.These data show a correlation between the appearance of vitellogenin in the oocyte, and the rise in ecdysteroids. A possible relationship to molting of the nematode, Onchocerca volvulus, is discussed.Blackflies are major nuisance pests and are vectors of the nematode, Onchocerca volvulus, which causes the serious human disease, onchocerciasis, mainly in tropical Africa but also in Central and South America. Microfilariae, ingested by the black fly from the human host, invade the thoracic muscles and molt several times. The steroid hormone, 20-hydroxyecdysone, is known to control molting in insects [1] and has been implicated in the control of molting of nematodes [2]. Ecdysteroids have been isolated from several parasitic nematodes [3], and have been shown to fluctuate in titer during the molt [4]. Genes related to the 20-hydroxyecdysone receptor gene of Drosophila melanogaster have been isolated from O. volvulus[5]. Interestingly, 20-hydroxyecdysone caused premature timing of the third stage molt of Dirofilaria immitis[6]. This raises the possibility that changes in ecdysteroid titer in the insect host could affect the timing of developmental molts of the parasitic nematode.20-hydroxyecdysone is important in the control of reproduction in Diptera, for example in Drosophila melanogaster[7,8
Pragmatism, Belief, and Reduction: Stereoformulas and Atomic Models in Early Stereochemistry
Peter J. Ramberg
Hyle : International Journal for Philosophy of Chemistry , 2000,
Abstract: In this paper I explore the character and role of stereoformulas and models of the atom that appeared in the early history of stereochemistry, including those of Jacobus Henricus van't Hoff, Aemilius Wunderlich, Johannes Wislicenus, Victor Meyer, Arthur Hantzsch, Alfred Werner, and Hermann Sachse. I argue that stereochemists constructed and used stereoformulas in a pragmatic way that ignored the physical implications of the spatial distribution of valence, and that the models of the atom were created to reconcile the physically curious concept of valence with known physical laws. Although such models were explanatory at a deeper level, they had little impact on the theory and practice of chemistry, and were not serious attempts to reduce chemical theory to physical laws.
Crawford, Elisabeth: "Arrhenius: From Ionic Theory to the Greenhouse Effect" (Canton 1996); and Diana Barkan: "Walther Nernst and the Transition to Modern Physical Science" (Cambridge 1999) (book review)
Peter J. Ramberg
Hyle : International Journal for Philosophy of Chemistry , 2000,
Abstract: book review of Crawford, Elisabeth: "Arrhenius: From Ionic Theory to the Greenhouse Effect" (Canton 1996); and Diana Barkan: "Walther Nernst and the Transition to Modern Physical Science" (Cambridge 1999)
Methods and Styles in the Development of Chemisty by Joseph S. Fruton
Peter J. Ramberg
Aestimatio : Critical Reviews in the History of Science , 2005,
Curando mentes, tratando cérebros: Psiquiatria entre biologia e subjetividade
Bj?rn Ramberg
Revista Redescri??es : Revista on-line do GT de Pragmatismo e Filosofia Norte-Americana , 2009,
ILCWS08 Test Beam Summary
Erik J. Ramberg
Physics , 2009,
Abstract: A summary is given of the high energy test beam facilities around the world. Attention is placed on the capabilities and availability of each. A short description is given of what kind of additional facilities are required in the future to support ILC detector research.
Activation of Akt Signaling Reduces the Prevalence and Intensity of Malaria Parasite Infection and Lifespan in Anopheles stephensi Mosquitoes
Vanessa Corby-Harris equal contributor,Anna Drexler equal contributor,Laurel Watkins de Jong,Yevgeniya Antonova,Nazzy Pakpour,Rolf Ziegler,Frank Ramberg,Edwin E. Lewis,Jessica M. Brown,Shirley Luckhart,Michael A. Riehle
PLOS Pathogens , 2010, DOI: 10.1371/journal.ppat.1001003
Abstract: Malaria (Plasmodium spp.) kills nearly one million people annually and this number will likely increase as drug and insecticide resistance reduces the effectiveness of current control strategies. The most important human malaria parasite, Plasmodium falciparum, undergoes a complex developmental cycle in the mosquito that takes approximately two weeks and begins with the invasion of the mosquito midgut. Here, we demonstrate that increased Akt signaling in the mosquito midgut disrupts parasite development and concurrently reduces the duration that mosquitoes are infective to humans. Specifically, we found that increased Akt signaling in the midgut of heterozygous Anopheles stephensi reduced the number of infected mosquitoes by 60–99%. Of those mosquitoes that were infected, we observed a 75–99% reduction in parasite load. In homozygous mosquitoes with increased Akt signaling parasite infection was completely blocked. The increase in midgut-specific Akt signaling also led to an 18–20% reduction in the average mosquito lifespan. Thus, activation of Akt signaling reduced the number of infected mosquitoes, the number of malaria parasites per infected mosquito, and the duration of mosquito infectivity.
Diversity, dispersal and disturbance: cladoceran species composition in the Okavango Delta
Markus Lindholm,Dag O. Hessen,Lars Ramberg
African Zoology , 2011,
Abstract: Communities exposed to intermediate disturbances have been shown to be more diverse than more stable or unstable systems. We recorded the diversity pattern of zooplankton in the Okavango Delta, Botswana, a system which include water bodies with different stability with regard to water levels and wet–dry phases, from permanent rivers and lagoons to seasonal floodplains and temporary water-filled rain ponds. The yearly flood pulse caused a gradual shift in aquatic parameters on seasonal floodplains, which promoted zooplankton diversity. Species composition differed between temporal and permanent habitats, but highest diversity was recorded on floodplains. Diversity on floodplains showed a distinct seasonal trend, being low during increasing flood, to highly diverse during high water periods. Density and hatching sequence of major cladoceran species suggested that the bank of resting eggs in the soil is the major source of species occurrence during flooding. We propose that seasonal floodplains, which have significant higher diversity and abundance, serve as source areas for the cladoceran diversity in the Okavango Delta. From these habitats ephippia are dispersed into the other four habitats. The dominant vectors for such dispersal are probably wind and mammals.
Immunomodulatory dietary polysaccharides: a systematic review of the literature
Jane E Ramberg, Erika D Nelson, Robert A Sinnott
Nutrition Journal , 2010, DOI: 10.1186/1475-2891-9-54
Abstract: Studies were identified by conducting PubMed and Google Scholar electronic searches and through reviews of polysaccharide article bibliographies. Only articles published in English were included in this review. Two researchers reviewed data on study design, control, sample size, results, and nature of outcome measures. Subsequent searches were conducted to gather information about polysaccharide safety, structure and composition, and disposition.We found 62 publications reporting statistically significant effects of orally ingested glucans, pectins, heteroglycans, glucomannans, fucoidans, galactomannans, arabinogalactans and mixed polysaccharide products in rodents. Fifteen controlled human studies reported that oral glucans, arabinogalactans, heteroglycans, and fucoidans exerted significant effects. Although some studies investigated anti-inflammatory effects, most studies investigated the ability of oral polysaccharides to stimulate the immune system. These studies, as well as safety and toxicity studies, suggest that these polysaccharide products appear to be largely well-tolerated.Taken as a whole, the oral polysaccharide literature is highly heterogenous and is not sufficient to support broad product structure/function generalizations. Numerous dietary polysaccharides, particularly glucans, appear to elicit diverse immunomodulatory effects in numerous animal tissues, including the blood, GI tract and spleen. Glucan extracts from the Trametes versicolor mushroom improved survival and immune function in human RCTs of cancer patients; glucans, arabinogalactans and fucoidans elicited immunomodulatory effects in controlled studies of healthy adults and patients with canker sores and seasonal allergies. This review provides a foundation that can serve to guide future research on immune modulation by well-characterized polysaccharide compounds.Polysaccharide-rich fungi and plants have been employed for centuries by cultures around the world for their dietary and medic
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