Septicæmic Pullorum Disease in a Flock of Adult Fowls     

L. Hart B.V.Sc.  T. G. Hungerford B.V.Sc.  H.D.A. 《Australian veterinary journal》1936,12(1):17-20

  相似文献   

PLANNING FOR THE FUTURE     

L. Hart 《Australian veterinary journal》1943,19(5):147-148

  相似文献   

THE OCCURRENCE OF SWINE ERYSIPELAS IN NEW SOUTH WALES.     

L. Hart  B.V.Sc.  H.D.A. 《Australian veterinary journal》1938,14(1):12-15

  相似文献   

Effect of thyrotropin‐releasing hormone stimulation testing on the oral sugar test in horses when performed as a combined protocol     

Elizabeth Hodge  Alycia Kowalski  Catherine Torcivia  Sue Lindborg  Darko Stefanovski  Kelsey Hart  Nicholas Frank  Andrew van Eps 《Journal of veterinary internal medicine / American College of Veterinary Internal Medicine》2019,33(5):2272-2279

  相似文献   

Leaf gas exchange characteristics differ among Sonoran Desert riparian tree species     

Horton JL  Kolb TE  Hart SC 《Tree physiology》2001,21(4):233-241

We investigated leaf gas exchange responses to leaf temperature, leaf-to-air vapor pressure deficit (VPD), and predawn and midday shoot water potential (psipd and psimd, respectively) of two native Sonoran Desert riparian tree species, Fremont cottonwood (Populus fremontii S. Wats.) and Goodding willow (Salix gooddingii Ball), and one exotic riparian tree species, saltcedar (Tamarix chinensis Lour. and related species). Measurements were made at two sites over 2 years that differed climatically. Because multiple linear regression models explained less than 29% of the variation in stomatal conductance (gs) and less than 48% of the variation in net photosynthetic rate (Pn) of all species, we used boundary-line analysis to compare gas exchange responses among species. Gas exchange rates were high in all species. The hyperbolic relationship between Pn and gs suggested that initial reductions in gs at high gs did not inhibit Pn. Reductions in gs of cottonwood and willow occurred at psimd values at or below previously reported xylem cavitation thresholds (-1.6 and -1.4 MPa, respectively), indicating tight stomatal regulation of water loss and a narrow cavitation safety margin. In contrast, reductions in gs of saltcedar occurred at psimd values well above the cavitation threshold (-7.0 MPa), but at much lower psimd values than in cottonwood and willow, suggesting a wider cavitation safety margin and less tight regulation of water loss in saltcedar. High VPD had a smaller effect on leaf gas exchange in willow than in cottonwood. In contrast, willow had a less negative psipd threshold for stomatal closure than cottonwood. Compared with cottonwood and willow, leaf gas exchange of saltcedar was more tolerant of high VPD and low psipd. These physiological characteristics of saltcedar explain its widespread success as an invader of riparian ecosystems containing native Fremont cottonwood and Goodding willow in the Sonoran Desert.  相似文献   

Boxelder water sources and physiology at perennial and ephemeral stream sites in Arizona     

Kolb TE  Hart SC  Amundson R 《Tree physiology》1997,17(3):151-160

To assess the influence of stream water on leaf gas exchange and water potential in different sized boxelder trees (Acer negundo L.), we compared these characteristics in trees growing beside a perennial stream and a nearby ephemeral stream in a montane-riparian forest in northern Arizona. Patterns of tree water use were quantified by stable isotope analysis (delta(18)O). Physiological characteristics were similar for large and small trees. Similarity between sites in predawn and daytime water potentials and xylem delta(18)O indicated that stream water was not a physiologically important water source. Seasonal and site variations in light-saturated net photosynthetic rate were significantly related to leaf-to-air vapor pressure deficit (r = -0.691) and foliar nitrogen concentration (r = 0.388). Although deep water was the dominant water source, surface soil water was utilized following precipitation, especially by small trees. We conclude that net carbon gain and severity of water stress are only weakly coupled to stream water availability.  相似文献   

A study of the transfer of tetracycline resistance genes between Escherichia coli in the intestinal tract of a mouse and a chicken model     

Hart WS  Heuzenroeder MW  Barton MD 《Journal of veterinary medicine. B, Infectious diseases and veterinary public health》2006,53(7):333-340

Experiments to demonstrate the transfer of genes within a natural environment are technically difficult because of the unknown numbers and strains of bacteria present, as well as difficulties designing adequate control experiments. The results of such studies should be viewed within the limits of the experimental design. Most experiments to date have been based on artificial models, which only give approximations of the real-life situation. The current study uses more natural models and provides information about tetracycline resistance as it occurs in wild-type bacteria within the environment of the normal intestinal tract of an animal. Tetracycline sensitive, nalidixic acid resistant Escherichia coli isolates of human origin were administered to mice and chicken animal models. They were monitored for acquisition of tetracycline resistance from indigenous or administered donor E. coli. Five sets of in vivo experiments demonstrated unequivocal transfer of tetracycline resistance to tetracycline sensitive recipients. The addition of tetracycline in the drinking water of the animals increased the probability of transfer between E. coli strains originating from the same animal species. The co-transfer of unselected antibiotic resistance in animal models was also demonstrated.  相似文献   

Bovine monocytes and a macrophage cell line differ in their ability to phagocytose and support the intracellular survival of Mycobacterium avium subsp. paratuberculosis     

Woo SR  Sotos J  Hart AP  Barletta RG  Czuprynski CJ 《Veterinary immunology and immunopathology》2006,110(1-2):109-120

Bovine monocytes exhibited a greater ability to phagocytose Mycobacterium avium subsp. paratuberculosis (i.e. greater percentage of infected cells, and more bacilli per infected cell), than did a bovine macrophage cell line (BoMac). Phagocytosis of M. paratuberculosis by monocytes, but not the cell line, was significantly enhanced by the addition of autologous serum. Following ingestion, the numbers of viable M. paratuberculosis cells in monocytes increased during the first 4 days and then declined between day 4 and day 8 after infection, as determined by a radiometric method. In contrast, BoMac cells were not permissive for bacillary multiplication; the numbers of M. paratuberculosis remained largely unchanged in the cell line during the 8 day incubation period. The numbers of microscopically visible acid-fast bacilli increased with time in monocytes but not in the macrophage cell line. These observations suggest that replication and inactivation of bacilli may both occur in monocytes. The differing abilities of bovine monocytes and the macrophage cell line to ingest and restrain the intracellular growth of M. paratuberculosis provide contrasting model systems for investigating how M. paratuberculosis enters and persists within its preferred niche, the mononuclear phagocyte.  相似文献   

High-resolution protein structure determination by serial femtosecond crystallography     

Boutet S  Lomb L  Williams GJ  Barends TR  Aquila A  Doak RB  Weierstall U  DePonte DP  Steinbrener J  Shoeman RL  Messerschmidt M  Barty A  White TA  Kassemeyer S  Kirian RA  Seibert MM  Montanez PA  Kenney C  Herbst R  Hart P  Pines J  Haller G  Gruner SM  Philipp HT  Tate MW  Hromalik M  Koerner LJ  van Bakel N  Morse J  Ghonsalves W  Arnlund D  Bogan MJ  Caleman C  Fromme R  Hampton CY  Hunter MS  Johansson LC  Katona G  Kupitz C  Liang M  Martin AV  Nass K  Redecke L  Stellato F  Timneanu N  Wang D  Zatsepin NA  Schafer D  Defever J 《Science (New York, N.Y.)》2012,337(6092):362-364

Structure determination of proteins and other macromolecules has historically required the growth of high-quality crystals sufficiently large to diffract x-rays efficiently while withstanding radiation damage. We applied serial femtosecond crystallography (SFX) using an x-ray free-electron laser (XFEL) to obtain high-resolution structural information from microcrystals (less than 1 micrometer by 1 micrometer by 3 micrometers) of the well-characterized model protein lysozyme. The agreement with synchrotron data demonstrates the immediate relevance of SFX for analyzing the structure of the large group of difficult-to-crystallize molecules.  相似文献   

Multilocus sequence typing of human and canine C. upsaliensis isolates     

Parsons BN  Porter CJ  Stavisky JH  Williams NJ  Birtles RJ  Miller WG  Hart CA  Gaskell RM  Dawson S 《Veterinary microbiology》2012,157(3-4):391-397

Risk of Campylobacter infection in humans has been associated with many sources, including dogs. C. upsaliensis is the most common species found in canines, and has been occasionally isolated from symptomatic humans. This study aimed to investigate the genetic diversity of 41 C. upsaliensis isolates carried by dogs and from nine isolates carried by humans using Multilocus sequence typing (MLST). We identified considerable genetic diversity amongst the C. upsaliensis isolates from both dogs and humans, identifying 45 different sequence types (STs). All STs were new, apart from that of the reference strain. Only three STs were found in more than one isolate: ST-72 (2 isolates), ST-98 (2 isolates) and ST-104 (3 isolates). ST-104 was the only ST to be encountered in both dogs and humans. Thirty-one of the 45 STs were assigned to one of 13 clonal complexes (CCs). Four of these CCs contained STs originating from both humans and dogs. None of the CCs contained exclusively human isolates, and two isolates from dogs within the same kennel belonged to the same CC. The large amount of diversity found in both dog and human isolates of C. upsaliensis, combined with the relatively small database, made it difficult to assign strains to sources of infection. This emphasizes the need to increase the size of the database. Dog and human isolates occasionally grouped together, however there were insufficient human-derived isolates to determine whether or not dogs are a common source of infection. Although C. upsaliensis infection is rare in humans, dogs still remain a potential source, and are therefore a possible zoonotic risk. Further work is needed to investigate the epidemiology of C. upsaliensis infection in humans.  相似文献