Direct competitive enzyme-linked immunosorbent assay for sulfamethazine residues in milk   总被引：1，自引：0，他引：1  

D E Dixon-Holland  S E Katz 《Journal of the Association of Official Analytical Chemists》1989,72(3):447-450

A direct competitive enzyme-linked immunosorbent assay (ELISA) is described for the detection and estimation of sulfamethazine residues in milk. Samples are cleaned up rapidly by acidifying and centrifuging the milk, adjusting the supernatant liquid to pH 7.0, and centrifuging again. The supernate is then assayed using set points to estimate sulfamethazine levels in the sample in the range of 1 ppb to 1 ppm. Multiple samples of milk can be screened in 1.5-2 h by this ELISA method.  相似文献   

Microbiological assay for chloramphenicol residues     

C J Singer  S E Katz 《Journal of the Association of Official Analytical Chemists》1985,68(5):1037-1041

Procedures for the assay of chloramphenicol in milk, urine, serum, and muscle tissue are presented. The procedures specify an assay design with all standards as well as samples present on each plate, oxytetracycline in the buffer-diluent for greater sensitivity, a minimal medium to enhance the inhibitory effect of chloramphenicol on the assay organism, and a tetrazolium dye to improve the ability to measure the zones of inhibition. Recoveries of unbound chloramphenicol from bovine urine were 90.8%, from serum 88.3%, from milk 79.3%, from swine muscle 71.3%, and from beef and chicken muscle 61.0 and 61.4%, respectively. The lower levels of measurement in urine and serum were 0.25 microgram/mL, 0.025 microgram/mL in milk, and 0.10 microgram/g in muscle tissue.  相似文献   

Exposure of pigs to a pseudorabies virus formed by in vivo recombination of two vaccine strains in sheep     

J B Katz  L M Henderson  G A Erickson  F A Osorio 《Journal of veterinary diagnostic investigation》1990,2(2):135-136

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A two-amino acid change in the hemagglutinin of the 1918 influenza virus abolishes transmission     

Tumpey TM  Maines TR  Van Hoeven N  Glaser L  Solórzano A  Pappas C  Cox NJ  Swayne DE  Palese P  Katz JM  García-Sastre A 《Science (New York, N.Y.)》2007,315(5812):655-659

The 1918 influenza pandemic was a catastrophic series of virus outbreaks that spread across the globe. Here, we show that only a modest change in the 1918 influenza hemagglutinin receptor binding site alters the transmissibility of this pandemic virus. Two amino acid mutations that cause a switch in receptor binding preference from the human alpha-2,6 to the avian alpha-2,3 sialic acid resulted in a virus incapable of respiratory droplet transmission between ferrets but that maintained its lethality and replication efficiency in the upper respiratory tract. Furthermore, poor transmission of a 1918 virus with dual alpha-2,6 and alpha-2,3 specificity suggests that a predominant human alpha-2,6 sialic acid binding preference is essential for optimal transmission of this pandemic virus. These findings confirm an essential role of hemagglutinin receptor specificity for the transmission of influenza viruses among mammals.  相似文献   

Organic transistors: two-dimensional transport and improved electrical characteristics     

Dodabalapur A  Torsi L  Katz HE 《Science (New York, N.Y.)》1995,268(5208):270-271

The thiophene oligomer alpha-hexathienylene (alpha-6T) has been successfully used as the active semiconducting material in thin-film transistors. Field-induced conductivity in thin-film transistors with alpha-6T active layers occurs only near the interfacial plane, whereas the residual conductivity caused by unintentional doping scales with the thickness of the layer. The two-dimensional nature of the field-induced conductivity is due not to any anisotropy in transport with respect to any molecular axis but to interface effects. Optimized methods of device fabrication have resulted in high field-effect mobilities and on/off current ratios of > 10(6). The current densities and switching speeds are good enough to allow consideration of these devices in practical large-area electronic circuits.  相似文献   

Detection of rabies virus antigen by the indirect rapid immunohistochemistry test in equines and comparisons with other diagnostic techniques     

Ranieli B. C. Torquato  Keila Iamamoto  Elaine R. Fernandes  Samira Achkar  Sandriana R. Silva  Iana S. S. Katz  Fernanda Guedes 《Zoonoses and public health》2020,67(6):651-657

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The large, oxygen-rich halos of star-forming galaxies are a major reservoir of galactic metals     

Tumlinson J  Thom C  Werk JK  Prochaska JX  Tripp TM  Weinberg DH  Peeples MS  O'Meara JM  Oppenheimer BD  Meiring JD  Katz NS  Davé R  Ford AB  Sembach KR 《Science (New York, N.Y.)》2011,334(6058):948-952

The circumgalactic medium (CGM) is fed by galaxy outflows and accretion of intergalactic gas, but its mass, heavy element enrichment, and relation to galaxy properties are poorly constrained by observations. In a survey of the outskirts of 42 galaxies with the Cosmic Origins Spectrograph onboard the Hubble Space Telescope, we detected ubiquitous, large (150-kiloparsec) halos of ionized oxygen surrounding star-forming galaxies; we found much less ionized oxygen around galaxies with little or no star formation. This ionized CGM contains a substantial mass of heavy elements and gas, perhaps far exceeding the reservoirs of gas in the galaxies themselves. Our data indicate that it is a basic component of nearly all star-forming galaxies that is removed or transformed during the quenching of star formation and the transition to passive evolution.  相似文献   

Tropopause detected by radar     

Atlas D  Hardy KR  Glover KM  Katz I  Konrad TG 《Science (New York, N.Y.)》1966,153(3740):1110-1112

The tropopause has been detected by ultrasensitive, narrow-beam, microwave (10.7-centimeter) and ultrahigh-frequency (71.5-cm) radars. Its reflectivity is consistent with that expected theoretically for a refractively turbulent medium. Indications are that the layer is also mechanically turbulent, and that electromagnetic scatter techniques may be used to detect high-altitude clear-air turbulence.  相似文献   

A truncated retrotransposon disrupts the GRM1 coding sequence in Coton de Tulear dogs with Bandera's neonatal ataxia     

Zeng R  Farias FH  Johnson GS  McKay SD  Schnabel RD  Decker JE  Taylor JF  Mann CS  Katz ML  Johnson GC  Coates JR  O'Brien DP 《Journal of veterinary internal medicine / American College of Veterinary Internal Medicine》2011,25(2):267-272

Background: Bandera's neonatal ataxia (BNAt) is an autosomal recessive cerebellar ataxia that affects members of the Coton de Tulear dog breed. Objective: To identify the mutation that causes BNAt. Animals: The study involved DNA from 112 Cotons de Tulear (including 15 puppies with signs of BNAt) and 87 DNA samples from dogs of 12 other breeds. Methods: The BNAt locus was mapped with a genome‐wide association study (GWAS). The coding exons of positional candidate gene GRM1, which encodes metabotropic glutamate receptor 1, were polymerase chain reaction (PCR)‐amplified and resequenced. A 3‐primer PCR assay was used to genotype individual dogs for a truncated retrotransposon inserted into exon 8 of GRM1. Results: The GWAS indicated that the BNAt locus was in a canine chromosome 1 region that contained candidate gene GRM1. Resequencing this gene from BNAt‐affected puppies indicated that exon 8 was interrupted by the insertion of a 5′‐truncated retrotransposon. All 15 BNAt‐affected puppies were homozygous for the insert, whereas all other Cotons de Tulear were heterozygotes (n = 43) or homozygous (n = 54) for the ancestral allele. None of the 87 dogs from 12 other breeds had the insertion allele. Conclusions and Clinical Importance: BNAt is caused by a retrotransposon inserted into exon 8 of GRM1. A DNA test for the GRM1 retrotransposon insert can be used for genetic counseling and to confirm the diagnosis of BNAt.  相似文献   

Characterization of the responses of equine digital veins and arteries to calcitonin gene-related peptide     

Katz LM  Marr CM  Elliott J 《American journal of veterinary research》2011,72(7):975-981

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