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A new method is presented for the determination of 2'-deoxythymidine 5'-triphosphate and 2'-deoxycytidine 5'-triphosphate concentrations within human cells based on a DNA polymerase reaction directed by a palindromic oligonucleotide precursor. Two 19-mer oligonucleotide precursors are employed that contain a common 8-mer palindromic sequence followed by a sequence-specific insertion site and a 5'-oligodeoxythymidylate tail. To conduct a measurement, two molecules of the 19-mer oligonucleotide precursor are first annealed to form a pair of symmetrical template-primer addition sites at their 3'-termini that are coded for the analyte of interest, present in limiting amounts. The Klenow fragment of Escherichia coli DNA polymerase I then elongates the template-primer by the addition of two molecules of the complementary deoxyribonucleotide analyte. Following the addition of the analyte molecules, the template-primer is extended with a 10-mer oligo(dA) tail in the presence of excess dATP and the Klenow fragment. The result is a 30-mer palindromic oligonucleotide that can be separated from any remaining 19-mer precursor and quantified by paired-ion HPLC using UV detection. Since the molar extinction coefficient of the 30-mer palindromic oligonucleotide is much larger than that of the nucleotide analyte alone, the UV signal is markedly enhanced, thereby increasing sensitivity. Details describing this method and the application of it to measure these analytes in as few as 2.5 x 10(6) human cells are presented.

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The encounter of phase I C. burnetii with the host results in seemingly disparate consequences. On the one hand, in vitro lymphocyte responses to mitogens and homologous recall antigen are suppressed. On the other, host resistance to a variety of infectious agents and to a tumor is increased. An explanation for this augmented immune response surely involves the ability of C. burnetii to stimulate cytokines, such as interferon and TNF, which enhance host immune function.

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Experimental results are presented to support the hypothesis that the shape and location of the active region of vibration in a thickness shear mode quartz resonator are the dominant factors in determining the acceleration sensitivity of the resonator. The shape and location of the mode in a real world resonator vary sufficiently from unit to unit (due to material and processing variations) that all other considerations are overwhelmed. It is shown experimentally that the mode shape and/or location can be trimmed with energy trapping by judicious addition or subtraction of mass to produce resonators with improved acceleration sensitivity.

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4 Egyptian mosquito species were tested for their ability to transmit the Egyptian ZH-501 strain of Rift Valley fever virus (RVFV) to golden Syrian hamsters. Culex (Cx.) antennatus was the most efficient vector, showing a 37.5% transmission rate following a hamster blood meal containing 10 suckling mouse intracerebral 50% lethal doses (SMILD50) per ml. Fully engorged mosquitoes of this species showed an infection rate of 85% with the mean viral titres of transmitting mosquitoes 100-fold higher than non-transmitters. Autogenous and anautogenous populations of Aedes (Ae.) caspius were tested separately, and the transmission rates were 23.1% and 9.7% respectively, following feeding on hamsters with similar levels of viraemia. Two anopheline species, Anopheles (An.) multicolor and An. pharoensis, showed 12.5% and 3.5% transmission rates under similar conditions. In these 3 species infection rates exceeded 75% and mosquitoes transmitting had a higher average titre than those not transmitting.

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The injection of a single dose containing 5 X 10(3) plaque forming units (PFU) of a minute plaque variant of Rift Valley fever virus (RVFV) into two susceptible lambs resulted in no detectable viremia, pyrexia or clinical signs of disease. Immunization with the minute plaque variant induced neutralizing antibody as early as seven days postinoculation; however, no complement fixing antibodies were detected. Lambs immunized in this manner were protected when challenged with an infectious dose containing 1 X 10(3) PFU of wild type RVFV. These data indicate that the minute plaque variant may hold promise as a candidate live virus animal vaccine.

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Variants of Rift Valley fever virus producing plaques in CER cells of four different sizes are described. A plaque-forming unit (PFU) variant forming minute plaques was isolated and purified. Virus derived from this variant was not pathogenic to adult Swiss albino mice by the intraperitoneal (i.p.) route and was less pathogenic than the parent strain (ZH501) to adult Sprague Dawley rats by i.p. route, but produced typical severe liver necrosis in adult Syrian hamsters with intranuclear and intracytoplasmic eosinophilic inclusions. Antigen and antiserum to the minute variant prepared in mice reciprocally cross-reacted with antisera and antigens of the original strain (ZH501) in the complement fixation test. Plaque size of the minute variant remained constant after serial passages in cell culture and in suckling mouse brain. When the minute plaque variant was passaged i.p. in hamsters, virus which formed large plaques in CER cells was recovered from the hamster sera.

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From 1974 through 1976, U.S. Naval Medical Research Unit No. 5 isolated 25 strain of tick-borne virus in infant mice from 410 pools containing over 6,000 ticks, and one strain from a bird and one strain from a rodent collected in central and southern Ethiopia. Of these, 17 were identified as known viruses previously found in West Central and East Africa. There were 8 strains of Jos virus from Amblyomma ticks; 7 strains of Dugbe virus from a bird, a rodent and from ticks; 1 strains of Crimean-Congo hemorrhagic fever virus and 1 strain of Thogoto virus from ticks.

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