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In rodents and humans, lymphocytes extravasate into lymph nodes via specialized paracortical venules lined with high endothelium (HEV). Sheep and other ruminants do not have morphologically defined HEV in their lymph nodes. It has been assumed that lymphocyte extravasation in these species proceeds via analogous structures; i.e., paracortical venules lined with low to medium endothelium. In this study, lymphocyte suspensions were prepared from surgically excised lymph nodes of sheep and labeled with an intracellular fluorescent dye, H33342. Labeled cells were infused intravenously back into donors, and sheep were killed at various intervals after infusion. Frozen sections of lymph nodes were examined microscopically for the location of labeled cells. Ten minutes after infusion, labeled cells were seen in the lumen of venules located in the paracortical region of the nodes. At later time points, cells were seen apparently migrating through the venule walls and in the adjacent paracortical tissue. Similar experiments were performed in which H33342-labeled murine lymphocytes were infused into syngeneic mice. When equivalent cell numbers (based on animal size) were infused, no obvious differences were seen between location and kinetics of appearance of labeled cells in lymph nodes of sheep compared to those of mice. These results indicate that lymphocyte extravasation in sheep proceeds via paracortical venules in lymph nodes. The function of these venules appears to be analogous to HEV in nonruminant species. 相似文献
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Experimental infection of normal and immunosuppressed pigs with Pseudomonas pseudomallei 总被引：1，自引：0，他引：1
AD THOMAS JC FORBES-FAULKNER TL D''ARCY JH NORTON D HOFFMANN 《Australian veterinary journal》1990,67(2):43-46
A single dose of 5 x 10(8) bacilli of Pseudomonas pseudomallei by intratracheal injection resulted in acute (21 cases) or chronic (19 cases) melioidosis in 40 of 48 pigs. Fifteen (10 acute and 5 chronic) had been immunosuppressed by cyclophosphamide before inoculation. The major clinical signs were initial fever, marked neutrophilia and, in the acute cases, respiratory distress. There were no signs of the nasal and ocular discharge, paresis or diarrhoea seen in acute cases in south-east Asia. The cyclophosphamide treatment caused a significant decrease in the neutrophil count by 7 d after inoculation in all 15 immunosuppressed pigs, and all were culture positive at necropsy. Eight of the 33 non-treated pigs were culture negative at necropsy. Pigs overcoming the initial phase of infection had more abscess-like nodules that were bacteriologically sterile at necropsy than the pigs with acute cases of melioidosis. P. pseudomallei was isolated predominantly from the spleen, lungs and the injection site. Although only one strain was used in this study, it is likely that Australian strains of P. pseudomallei are not as virulent as the south-east Asian isolates. 相似文献
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Cryptosporidium parvum is a protozoan parasite that causes intestinal infection in a variety of mammals. We have previously described a factor in adult rat or adult bovine intestinal mucosa that protects against C. parvum infection when fed to susceptible infant rats. This factor is absent in intestinal mucosa from bovine calves. In the present study we describe the further characterization of the active component of bovine intestinal mucosa. The ability to protect infant rats against C. parvum infection was found to be associated with the extrinsic membrane protein fraction of the intestinal mucosa. Extrinsic membrane preparations from adult cows, adult rats, and calves were separated by SDS-PAGE. A band with apparent molecular mass of 54 kDa was seen in preparations from adult rat and cow, but not calf. Protein was transferred to PVDF membrane and from this the band was excised and subjected to N-terminal sequence analysis using a gas-phase protein sequenator. A 15-amino acid consensus sequence was generated with homology to leucine aminopeptidase (LAP). Purified LAP was purchased from a commercial source and tested for ability to protect infant rats against C. parvum infection. Rats fed LAP from 7 to 11 days of age and challenged with C. parvum at 9 days were significantly less infected than controls upon necropsy at 15 days of age. These data suggest that a protein with N-terminal sequence homology to LAP may reduce susceptibility of infant rats to C. parvum infection. 相似文献
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RL Westemeier JD Brawn SA Simpson TL Esker RW Jansen JW Walk EL Kershner JL Bouzat KN Paige 《Science (New York, N.Y.)》1998,282(5394):1695-1698
Effects of small population size and reduced genetic variation on the viability of wild animal populations remain controversial. During a 35-year study of a remnant population of greater prairie chickens, population size decreased from 2000 individuals in 1962 to fewer than 50 by 1994. Concurrently, both fitness, as measured by fertility and hatching rates of eggs, and genetic diversity declined significantly. Conservation measures initiated in 1992 with translocations of birds from large, genetically diverse populations restored egg viability. Thus, sufficient genetic resources appear to be critical for maintaining populations of greater prairie chickens. 相似文献
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Long‐term Effects of Pyrethrin and Cyfluthrin,a Type II Synthetic Pyrethroid,Insecticide Applications on Bull Reproductive Parameters 
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下载免费PDF全文 JL Stewart CF Shipley FA Ireland VL Jarrell CL Timlin DW Shike TL Felix 《Reproduction in domestic animals》2016,51(5):680-687
The objectives of this study were to determine effects of cyfluthrin and pyrethrin spray products, used in combination with cyfluthrin topical and ear tag applications, on bull reproductive parameters over 18 weeks. Angus or Angus x Simmental bulls were randomly assigned to one of three treatment groups: (i) no exposure to pyrethrins/cyfluthrin (CONT; n = 10), (ii) cyfluthrin ear tag and topical applications (ET; n = 10), or (iii) cyfluthrin ear tag, topical, premise spray and pyrethrin fog spray applications (ET+S; n = 8). Bull body weight was measured every 3 week, and body condition score and scrotal circumference were recorded on weeks 0, 9 and 18. Semen and serum were collected every 3 weeks for sperm evaluation and testosterone measurement, respectively. There was a treatment × week interaction (p < 0.01) for sperm with primary defects; bulls in CONT group had a greater (p = 0.01) percentage of sperm with primary defects than bulls treated with insecticides at week 18. Overall and progressive sperm motility, normal sperm morphology, secondary sperm defects and serum testosterone concentrations changed (p < 0.01) over time in all bulls; however, treatment did not affect (p ≥ 0.13) any of these parameters. There were also no treatment effects (p ≥ 0.08) on bull body weight, body condition score or scrotal circumference. The use of pyrethrin‐ and cyfluthrin‐based insecticides, regardless of application, did not negatively affect reproductive parameters in beef bulls when administered over 18 weeks. 相似文献
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Harp JA 《Animal health research reviews / Conference of Research Workers in Animal Diseases》2003,4(1):53-62
Cryptosporidium parvum is recognized as a major cause of diarrheal disease in neonatal bovine calves. In addition, this protozoan parasite has emerged as an important cause of disease in both immunocompromised and immunocompetent humans. Despite years of research, no consistently effective means of prevention or treatment are readily available for cryptosporidiosis in any species. Infection through ingestion of contaminated water has been widely documented; C. parvum was reported to be responsible for the largest waterborne outbreak of infectious disease in US history. In addition to its role as a primary disease agent, C. parvum has potential to initiate or exacerbate other gastrointestinal disorders, such as inflammatory bowel disease. Thus, control of C. parvum infection in both animals and humans remains an important objective. Research in our laboratory has focused on understanding mechanisms of resistance to C. parvum. We have demonstrated that acquisition of intestinal flora increases resistance to C. parvum. Substances present in the intestinal mucosa of adult animals can transfer resistance when fed to susceptible infants. Both expression of intestinal enzymes and rate of proliferation of epithelial cells may be altered following C. parvum infection. These and other changes may have profound effects on host resistance to C. parvum. 相似文献
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J A Harp M E Kehrli D J Hurley R A Wilson T C Boone 《Veterinary immunology and immunopathology》1991,28(1):29-35
To determine if periparturient immunosuppression in dairy cattle might be due to an alteration in total numbers of percent of T lymphocytes, we examined the numbers and percent of T lymphocyte subsets in peripheral blood from periparturient dairy cows, some of which received recombinant bovine granulocyte colony stimulating factor (rbG-CSF) during the study. Beginning 2 weeks preparatum through 4 weeks postpartum, peripheral blood mononuclear cells (PBMC) were collected and labeled with monoclonal antibodies to BoCD5, BoCD4, and BoCD8, and the percent of cells positive for each marker measured by flow cytometry. The percent of PBMC expressing BoCD5 (total T cells), and BoCD8 (T suppressor/cytotoxic cells) was not significantly different between the groups, or at different times before and after calving. The percent of PBMC expressing BoCD4 (T helper cells) was not significantly different between the groups, however, within both groups there was a higher percent of BoCD4+ cells after calving than during the prepartum period. In cows receiving rbG-CSF, total numbers of PBMC were significantly increased compared to controls during the postpartum treatment period. 相似文献
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Neutrophils are essential components of the innate immune system and they play a critical role in the defense of host against bacterial and fungal infections. The colony stimulating factors are a class of glycoproteins that are required for proliferation, differentiation, and functional activation of hematopoietic progenitor cells. Granulocyte-colony stimulating factor (G-CSF) is a member of this regulatory family of cytokines that specifically stimulates proliferation and maturation of precursor cells in the bone marrow into fully differentiated and functional neutrophils. G-CSF also modulates the biological activities of mature neutrophils in circulation. A bovine G-CSF (bG-CSF) cDNA clone (previously isolated and sequenced in our laboratory) was expressed in Escherichia coli and the biological activities of the solubilized protein from purified inclusion bodies were examined. Flow cytometric analysis of membrane antigen density of neutrophils activated with bG-CSF revealed an upregulation in the expression of CD11a (>114%), CD11b (>148%), CD11c (>87%), and CD18 (>109%). Expression of L-selectin was decreased by more than 43%. There was no change, however, in the expression of CD14. These findings indicate that recombinant bG-CSF (rbG-CSF) expressed in E. coli is biologically active and exerts the same type of effects on neutrophils in vitro as those of human G-CSF (hG-CSF). 相似文献
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TL Morkved M Lu AM Urbas EE Ehrichs HM Jaeger P Mansky TP Russell 《Science (New York, N.Y.)》1996,273(5277):931-933
Local control of the domain orientation in diblock copolymer thin films can be obtained by the application of electric fields on micrometer-length scales. Thin films of an asymmetric polystyrene-polymethylmethacrylate diblock copolymer, with cylindrical polymethylmethacrylate microdomains, were spin-coated onto substrates previously patterned with planar electrodes. The substrates, 100-nanometer-thick silicon nitride membranes, allow direct observation of the electrodes and the copolymer domain structure by transmission electron microscopy. The cylinders aligned parallel to the electric field lines for fields exceeding 30 kilovolts per centimeter, after annealing at 250°C in an inert atmosphere for 24 hours. This technique could find application in nanostructure fabrication. 相似文献