Planetary radio astronomy observations from voyager 2 near saturn     

Warwick JW  Evans DR  Romig JH  Alexander JK  Desch MD  Kaiser ML  Aubier M  Leblanc Y  Lecacheux A  Pedersen BM 《Science (New York, N.Y.)》1982,215(4532):582-587

Planetary radio astronomy measurements obtained by Voyager 2 near Saturn have added further evidence that Saturnian kilometric radiation is emitted by a strong dayside source at auroral latitudes in the northern hemisphere and by a weaker source at complementary latitudes in the southern hemisphere. These emissions are variable because of Saturn's rotation and, on longer time scales, probably because of influences of the solar wind and Dione. The electrostatic discharge bursts first discovered by Voyager 1 and attributed to emissions from the B ring were again observed with the same broadband spectral properties and an episodic recurrence period of about 10 hours, but their occurrence frequency was only about 30 percent of that detected by Voyager 1. While crossing the ring plane at a distance of 2.88 Saturn radii, the spacecraft detected an intense noise event extending to above 1 megahertz and lasting about 150 seconds. The event is interpreted to be a consequence of the impact, vaporization, and ionization of charged, micrometer-size G ring particles distributed over a vertical thickness of about 1500 kilometers.  相似文献   

Induction of AIDS in rhesus monkeys by molecularly cloned simian immunodeficiency virus   总被引：92，自引：0，他引：92  

H Kestler  T Kodama  D Ringler  M Marthas  N Pedersen  A Lackner  D Regier  P Sehgal  M Daniel  N King 《Science (New York, N.Y.)》1990,248(4959):1109-1112

Better understanding of the pathogenesis of acquired immunodeficiency syndrome (AIDS) would be greatly facilitated by a relevant animal model that uses molecularly cloned virus of defined sequence to induce the disease. Such a system would also be of great value for AIDS vaccine research. An infectious molecular clone of simian immunodeficiency virus (SIV) was identified that induces AIDS in common rhesus monkeys in a time frame suitable for laboratory investigation. These results provide another strong link in the chain of evidence for the viral etiology of AIDS. More importantly, they define a system for molecular dissection of the determinants of AIDS pathogenesis.  相似文献   

The discovery of crown ethers     

Pedersen CJ 《Science (New York, N.Y.)》1988,241(4865):536-540

The discovery of the crown ethers stemmed from efforts to control the catalytic activity of vanadium and copper by complexation with multidentate ligands. The first crown ether, 2,3,11,12-dibenzo-1,4,7,10,13,16-hexaoxacyclo-octadeca-2,11-diene, was obtained in 0.4% yield during an attempt to prepare a phenolic ligand from catechol and bis(2-chloroethyl)ether. This compound, which complexed with the sodium cation, was the first compound known to display such activity and became known as dibenzo-18-crown-6, an 18-atom heterocycle containing 6 oxygen atoms. Some 60 related compounds were made involving heterocyclic rings containing 12 to 60 atoms including 4 and 10 oxygen atoms. There are optimum polyether ring sizes for the different alkali metal cations: 15 to 18 for sodium, 18 for potassium, and 18 to 21 for cesium. Complexes having polyether to cation ratios of 1:1, 3:2, and 2:1 were prepared. Solubilization of inorganic salts in aprotic solvents, especially by saturated crown ethers, was demonstrated.  相似文献   

Ventilation Flow in Pig Houses measured and calculated by Carbon Dioxide, Moisture and Heat Balance Equations   总被引：3，自引：0，他引：3  

V. Blanes  S. Pedersen 《Biosystems Engineering》2005,92(4):498

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Comparative efficacy of three commercial feline leukemia virus vaccines against methylprednisolone acetate-augmented oronasal challenge exposure with virulent virus.     

N C Pedersen  L Johnson 《Journal of the American Veterinary Medical Association》1991,199(10):1453-1455

Three commercial FeLV vaccines, (A, B, and C) were purchased on the open market and administered to 8- to 20-week-old specific-pathogen-free kittens, according to manufacturers' instructions. A similar group of nonvaccinated kittens served as controls. All kittens were challenge-exposed oronasally with virulent FeLV 4 weeks after the final vaccination. Serum samples were monitored for FeLV-p27 antigenemia using an ELISA at 1- to 2-week intervals for at least 16 weeks after the last day of challenge exposure. Kittens that were either transiently (1 to 4 weeks) or never viremic during this period were counted as recovered, whereas kittens that became viremic and retained viremia for at least 10 weeks were counted as persistently viremic. The 3 vaccines were found to be 39% (vaccine C), 28% (vaccine B), and 17% (vaccine A) efficacious in preventing persistent viremia in immunized, compared with nonimmunized kittens.  相似文献   

Mitral valve prolapse in 3-year-old healthy Cavalier King Charles Spaniels. An echocardiographic study.   总被引：2，自引：0，他引：2       下载免费PDF全文

H D Pedersen  B O Kristensen  K A Lorentzen  J Koch  A L Jensen    A Flagstad 《Canadian journal of veterinary research》1995,59(4):294-298

Clinical studies have shown that Cavalier King Charles Spaniels (CKCS) have a high prevalence of mitral valvular insufficiency (MVI). Echocardiography has the potential to disclose early valvular changes, and the present prospective study was designed to investigate the occurrence of mitral valve prolapse (MVP) in young CKCS without heart murmurs, and to correlate the degree of MVP with the clinical status of the dogs by including CKCS with MVI as well. The study was based on blinded evaluations of echocardiographic recordings of mitral valves from 34 CKCS and 30 control dogs. Thirteen (87%) of 15 three-year-old CKCS without heart murmurs had MVP (2 total and 11 partial), as compared with 1 (7%) of 15 three-year-old normal Beagle dogs (P < 0.0001), and none of 15 three-year-old normal Medium Size Poodles (P < 0.0001). Of 19 CKCS with MVI, MVP was found in 84% of the entire group and in 100% of dogs with pulmonary congestion or edema. The occurrence of total MVP tended to be higher in the group with MVI (47%, 9/19), when compared with the younger CKCS without heart murmurs (13%, 2/15, P = 0.06). MVP was positively associated with excessive heart rate variability (P = 0.003). The radius of curvature of the anterior mitral valve leaflet in systole was significantly reduced in dogs with MVP when compared with those without (P < 0.0001). In conclusion, this study shows that CKCS at an early age have a high occurrence of MVP. This suggests: 1) A genetic predisposition of CKCS to MVP; and 2) That MVP is a pathogenetic factor in the development of mitral valvular insufficiency. Follow up studies may add further support to these proposals, and clarify whether echocardiography may be an aid in selecting CKCS for future breeding.  相似文献   

Synthesis and insect growth regulating activity of thiosemicarbazones of methyl 2-pyridyl ketones     

Lars-Erik K. Pedersen  Axel Svendsen  Per D. Klemmensen 《Pest management science》1984,15(5):462-470

Thirty-six thiosemicarbazones of methyl 2-pyridyl ketone and of some other methyl ketones were tested on Dysdercus cingulatus, Drosophila melanogaster, Locusta migratoria, Aedes aegypti, Tenebrio molitor and Musca domestica. Several derivatives were toxic, delaying or preventing ecdysis. The structure-activity relationship is discussed. The mode of action of these compounds appears to be different from that of juvenile hormones, anti-juvenile hormones, or chitin biosynthesis inhibitors.  相似文献   

Recovery of microorganisms from synovial and pleural fluids of animals using hyperosmolar media     

A. Matheson Buchanan  D.C. Davis  N.C. Pedersen  B.L. Beaman 《Veterinary microbiology》1982,7(1):19-33

L-phase (CWD) broth and plate media were used in parallel with conventional microbiological media during a 3-year period for culturing synovial and pleural fluids of animals. Two kinds of recoveries were obtained where parallel conventional methods were negative: (1) parent or normal bacteria, in very low numbers; and (2) Type B CWD variants in equally low numbers. Organisms in group 1 were: Streptococcus zooepidemicus from horses (2X); β-hemolytic streptococci, Lancefield Gp. G (2X); Staphylococcus aureus; Actinobacillus, and Actinomyces viscosus. Group 2 consisted of Bacteroides sp., Propionibacterium acnes, and three “Nocardia-like” sp. Catalase + Actinomyces was not recovered equally well on CWD plates as on conventional media with fluids obtained during ampicillin treatment. This occurred in spite of the fact that the CWD media was shown to support growth and reversion of laboratory induced L-phase variants of Nocardia caviae and N. asteroides, and had facilitated recovery of a Bacteroides L-phase variant from a pleural fluid. The nature of this fault in the media is under investigation in this laboratory.  相似文献   

Course of feline leukemia virus infection and its detection by enzyme-linked immunosorbent assay and monoclonal antibodies   总被引：6，自引：0，他引：6  

H Lutz  N C Pedersen  G H Theilen 《American journal of veterinary research》1983,44(11):2054-2059

Monoclonal antibodies specific for 3 distinct epitopes of the species-specific determinants of feline leukemia virus (FeLV) p27 were used in an enzyme-linked immunosorbent assay (ELISA) for measurement of serum p27 in cats infected with FeLV. Group-specific antigen (GSA) of FeLV in peripheral blood leukocytes was also determined by an immunofluorescence assay. Antibodies to FeLV and the feline oncornavirus-associated cell membrane antigen (FOCMA) were also measured. Thirty-six cats were surveyed and assigned to 4 categories. Five developed persistent viremia (category 1), characterized by continuous expression of p27, GSA, and low antibody titers to FeLV and FOCMA. Eleven cats with transient viremia (category 2) and 13 cats that were never detectably viremic (category 3), as judged by absence of GSA and p27, developed increased antibody titers to FeLV and FOCMA. Seven cats were never viremic, as judged by the GSA in the peripheral blood leukocytes, but still had detectable serum p27 (category 4). Most category 4 cats developed high antibody titers against FOCMA and/or FeLV. Of 307 field cats examined, 7% of the healthy cats and 10% of the sick cats could be assigned to category 4. However, this difference was not significant (P greater than or equal to 0.05). Of 26 cats with neoplasms 2 (1 of 12 with lymphosarcoma) could be classified as category 4. Because virus could be isolated from 2 category 4 cats, they were considered immune carriers.  相似文献   

Persistent upregulation of MHC class II antigen expression on T-lymphocytes from cats experimentally infected with feline immunodeficiency virus.     

B A Rideout  P F Moore  N C Pedersen 《Veterinary immunology and immunopathology》1992,35(1-2):71-81

A significant elevation in the percentage of CD4+ and CD8+ T-lymphocytes expressing major histocompatibility complex (MHC) Class II antigens was observed in the blood of cats shortly after they were experimentally infected with feline immunodeficiency virus (FIV). In addition to an increase in the relative proportion of T-lymphocytes expressing Class II antigens, there was an increase in the density of Class II antigens on the cell surface. These elevations were still evident at the completion of the 5 month study. A second group of cats that had been infected with FIV for almost 5 years, and with either normal or abnormally low levels of CD4+ T-lymphocytes, had similar elevations in MHC II expression, suggesting that such abnormalities are lifelong. Cats with chronic (2 year) feline leukemia virus (FeLV) infection or dual FIV/FeLV infections also showed similar alterations in MHC II expression on CD4+ and CD8+ T-lymphocytes, suggesting that these alterations were not FIV specific. Feline T-lymphocytes expressed more MHC II antigen and interleukin-2 (IL-2) receptor following stimulation in vitro with conconavalin A and IL-2, demonstrating that feline T-lymphocytes respond to activation signals in a manner similar to T-lymphocytes of other species. However, changes in MHC II expression on T-cells of FIV infected cats were not explainable by viral induced T-cell activation alone, because FIV infected cats with elevated MHC II expression did not have coincident elevations in IL-2 receptor expression.  相似文献