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S. Frink B. Grummer J. F. Pohlenz E. M. Liebler‐Tenorio 《Zoonoses and public health》2002,49(10):476-483
Mucosal disease (MD), one sequelae of bovine virus diarrhoea virus (BVDV) infection, causes severe lesions in lymphoid tissues and mucosal surfaces. Lesions are associated with the presence of cytopathogenic (cp) BVDV and initially characterized by apoptotic cell death. The objective of this investigation was to determine if this cell death is mediated only by the cp BVDV, which is known to induce apoptosis in cell culture or if immune‐mediated host reactions might also contribute. Early onset MD was experimentally induced in calves by inoculation of persistently viremic calves with a closely related cp BVDV. Calves were euthanized in the early phase of infection between days 5 and 13 post‐inoculation and tissues from tonsils, lymph nodes, Peyer's patches, jejunum and colon were collected. Presence of cp BVDV antigen was correlated with distribution of lymphocyte subpopulations in consecutive cryostat sections. In the lymphoid tissues, cp BVDV antigen was predominantly found in the lymphoid follicles. The increase of infected cells with time post‐inoculation was paralleled by a decrease of B‐lymphocytes and an increase of CD4+ T‐lymphocytes. An increased number of CD8+ T‐lymphocytes was seen in progressed lesions only. In the intestinal mucosa, initially multifocal, later diffuse infection with cp BVDV was accompanied by a multifocal or diffuse increase of CD4+ T‐lymphocytes, respectively. Numbers of IgA+ plasma cells and CD8+ T‐lymphocytes were decreased. The common change observed in lymphoid tissues and mucosa was the increase of CD4+ T‐lymphocytes in sites with lesions. This might indicate a cell‐mediated immune response to the cp BVDV. Besides their helper function to other cells of the immune system, activated CD4+ T‐lymphocytes might also exert cytotoxic activity, induce apoptosis in target cells via Fas/Fas ligand binding and thus contribute to the severity of tissue lesions in MD. 相似文献
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Unmanaged soils in the northeast United States generally tend toward increasing acidity which results from several natural processes in the soil. Possible effects of acid precipitation on these processes may be caused by hydrogen ions associated with excess anions in the precipitation and, in addition, the anions may also have specific effects. This is especially true for N and S both of which have important biological implications. It is likely that direct effects of the H ion will be modest. As an example, the acidity in 114 cm of rainfall per year (Connecticut's average) with a pH of 4.3 would require 28.5 kg ha ?1 of limestone for neutralization. By contrast agronomic practice in Connecticut frequently dictates limestone additions as high as several thousand kg ha?1 to neutralize acidity generated by a combination of natural processes and fertilizer amendments. Studies of rainfall composition in Connecticut from 1929 to 1948 showed no clear trends with time and indicated levels of sulfate and nitrate in rainwater similar to those reported today. In a 10 yr lysimeter study in Connecticut in which tobacco was grown using conventional fertilization techniques, soil pH decreased from 5.4 to 5.0 and both gains and losses of soil cations were recorded. Thus it appears that changes in unmanaged soils induced by acid precipitation alone will be modest and subtle and probably cannot be expressed completely by measuring changes in soil pH value. 相似文献
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Acid rain on Acid soil: a new perspective 总被引：1，自引：0，他引：1
Acid rain is widely believed to be responsible for acidifying soil and water in areas of North America and northern Europe. However, factors commonly considered to make landscapes susceptible to acidification by acid rain are the same factors long known to strongly acidify soils through the natural processes of soil formation. Recovery from extreme and widespread careless land use has also occurred in regions undergoing acidification. There is evidence that acidification by acid rain is superimposed on long-term acidification induced by changes in land use and consequent vegetative succession. Thus, the interactions of acid rain, acid soil, and vegetation need to be carefully examined on a watershed basis in assessing benefits expected from proposed reductions in emissions of oxides of sulfur and nitrogen. 相似文献
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Corral Lucia Stuber Erica F. Frink Teresa J. Bishop Andrew A. Fontaine Joseph J. 《Landscape Ecology》2022,37(1):249-266
Landscape Ecology - Niche theory is frequently used as a framework to integrate environmental variables and species interactions to describe species geographic distribution. Yet, the scale at which... 相似文献
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Bras JJ Lillich JD Beard WL Anderson DE Armbrust LJ Frink E Lease K 《Veterinary surgery : VS》2011,40(1):73-81
Objective: To (1) compare the effect of a collateral ligament sparing surgical approach with an open surgical approach on mechanical properties of proximal interphalangeal joint (PIPJ) arthrodesis, and (2) to determine the percentage of articular cartilage surface removed by transarticular (TA) drilling with different diameter drill bits. Study Design: Randomized paired limb design. Sample Population: Cadaveric equine limbs (n=76). Methods: Cadaveric PIPJ were drilled using a 3.5, 4.5, or 5.5 mm drill bit at 80–84° to the dorsal plane to remove articular cartilage and subchondral bone from the distal articular surface of the proximal phalanx (P1) and the proximal articular surface of the middle phalanx (P2). Bone ends were photographed and the percentage of the projected surface area that was denuded of cartilage was measured. PIPJ arthrodesis constructs (3‐hole dynamic compression plate [DCP], two 5.5 mm TA screws inserted in lag fashion, medial and lateral to the DCP; DCP‐TA) were created using 2 surgical approaches in paired limbs. A conventional open approach was used in 1 limb and a collateral ligament sparing approach used in the other limb. Constructs were tested to failure in single‐cycle 3‐point dorsopalmar/plantar or lateromedial bending. Maximum load, yield load, and composite stiffness were compared between techniques. Results: The 3.5, 4.5, and 5.5 mm drill bits removed 24±4%, 35±5%, and 45±7% of total PIPJ articular cartilage surface, respectively. Constructs with the collateral ligament sparing approach had significantly greater mean yield load (11.3±2.8 versus 7.68±1.1 kN, P=.008) and mean maximum load (13.5±3.1 versus 10.1±1.94 kN, P=.02) under lateromedial bending. Under dorsopalmar/plantar bending there was no significant difference between surgical approaches. The collateral ligament sparing arthrodesis technique had a shorter surgical time (19±3 minutes) compared with the open technique (31±3 minutes). Conclusion: A collateral ligament sparing surgical approach to the PIPJ with removal of articular cartilage by TA drilling and arthrodesis by DCP‐TA was faster and stronger in mediolateral bending than arthrodesis constructs created with an open surgical approach. Clinical Relevance: Preservation of the collateral ligaments and TA drilling for cartilage removal during PIPJ arthrodesis may be a superior approach to the conventional open approach and warrants clinical evaluation. 相似文献
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Frink S Grummer B Pohlenz JF Liebler-Tenorio EM 《Journal of veterinary medicine. B, Infectious diseases and veterinary public health》2002,49(10):476-483
Mucosal disease (MD), one sequelae of bovine virus diarrhoea virus (BVDV) infection, causes severe lesions in lymphoid tissues and mucosal surfaces. Lesions are associated with the presence of cytopathogenic (cp) BVDV and initially characterized by apoptotic cell death. The objective of this investigation was to determine if this cell death is mediated only by the cp BVDV, which is known to induce apoptosis in cell culture or if immune-mediated host reactions might also contribute. Early onset MD was experimentally induced in calves by inoculation of persistently viremic calves with a closely related cp BVDV. Calves were euthanized in the early phase of infection between days 5 and 13 post-inoculation and tissues from tonsils, lymph nodes, Peyer's patches, jejunum and colon were collected. Presence of cp BVDV antigen was correlated with distribution of lymphocyte subpopulations in consecutive cryostat sections. In the lymphoid tissues, cp BVDV antigen was predominantly found in the lymphoid follicles. The increase of infected cells with time post-inoculation was paralleled by a decrease of B-lymphocytes and an increase of CD4+ T-lymphocytes. An increased number of CD8+ T-lymphocytes was seen in progressed lesions only. In the intestinal mucosa, initially multifocal, later diffuse infection with cp BVDV was accompanied by a multifocal or diffuse increase of CD4+ T-lymphocytes, respectively. Numbers of IgA+ plasma cells and CD8+ T-lymphocytes were decreased. The common change observed in lymphoid tissues and mucosa was the increase of CD4+ T-lymphocytes in sites with lesions. This might indicate a cell-mediated immune response to the cp BVDV. Besides their helper function to other cells of the immune system, activated CD4+ T-lymphocytes might also exert cytotoxic activity, induce apoptosis in target cells via Fas/Fas ligand binding and thus contribute to the severity of tissue lesions in MD. 相似文献
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Samples of ash from municipal refuse incinerators in six Connecticut towns as well as samples of incinerated sewage sludge were collected during 1988 and 1989. The samples were analyzed for pH, metal content by HNO3 + H2O2 digestion, extractable metals by solvents including NaOAc, DTPA, H2CO3 and H2O. Two samples were examined for metals that could be leached by H2O from laboratory columns. Most ash samples were highly alkaline and their pH changed slowly, decreasing by about two pH units over a 6-week period. The variability in metal content of ash from different incinerators was similar to that observed in samples obtained from the same facility at different times. Only a portion of the metals were extracted by the solvents in the order NaOAc > DTPA > H2CO3 > H2O. The relative amounts of the total metals in the ash that could be extracted with specific solvents varied widely, suggesting different chemical forms in different ashes. After the initial removal of large concentrations of metals in the leachates from laboratory columns over 2 to 3 days, leaching of metals continued at extremely low concentrations that were generally below drinking water standards. 相似文献
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Simulated acid rains of pH 5.6, 4.0, 3.5, 3.0, 2.5, or 2.0 were applied to leaves of broadleaf tobacco twice per week for 1, 2, 3, 4, or 5 weeks. Only those plants receiving rain of pH 2.0 were injured and, among those, the plants receiving fewer applications had less severe injury. Foliar symptoms resembled weather fleck (O3 injury) at first, but become distinguishable from them with time. 相似文献
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