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91.
LIN Chu-Xia 《土壤圈》1996,6(1):1-10
In the Pearl River Delta with more than 1000 years of intensive land reclamation history,the development of acid sulphate soils has been generally limited in terms of their acid potential (pyrite content)and spatial extent.This is attributed to the rapid delta progradation,partially resulted from increasing sediment yield caused by deforestation within the catchment and the empolderment in the estuarine embayment.The empolderment practice accompanied by the clearance of mangroves stopped the upward growth of the pyritic layer on the one hand and limited the vertical accretion of non-pyritic freshwater sediments over the pyritic layer on the one hand and limited the vertical accretion of non-pyritic freshwater sediments over the pyritic estuarine sediments on the other.In such a case,the pyritic layer in the area is frequently thin and of shallow occurrence.Under forced leaching-recharge conditions for the paddy rice cultivation ,the leaching of acid sulphate materials prevails over its production and this leads to a net loss in pyrite oxidation products.Land excavation for fishpond farming accelerates pyrite oxidation due to the direct exposure of the pyrtic sediments to air on the pond bunds.Severe acidification can intensity the environmental degradation of estuarine ecosystems. 相似文献
92.
基于GIS的典型岩溶流域土地利用变化分析——以云南省小江流域为例 总被引:5,自引:0,他引:5
在GIS支持下,利用云南小江流域两期土地利用图形数据叠加分析,得到土地利用变化图和土地利用转移矩阵。结果发现,1982—2003年全流域610.12km2的土地利用面积发生变化,占流域总面积的59%。土地利用的类型主要是由未利用地向耕地和林地以及林地向耕地的转化,流域综合土地利用变化动态度达2.95%。土地利用空间格局的基本构型由以大斑块为主体,散布型斑块镶嵌其中转变为以中等斑块为主体,散布型斑块镶嵌其中的构型;区域土地利用的斑块数由1014个增加到1889个,平均斑块面积由1.02km2/个减少到0.55km2/个;流域土地利用空间格局指数中多样性指数增长4.14%,均匀度指数增长4.14%,破碎度指数增长84.6%,优势度指数降低1.6%;未利用地、林地的分离度分别增加114.58%和69.64%,而耕地的分离度减少45.86%;流域耕地、建设用地重心向东北方向偏移,而未利用地、林地重心向南东、南西方向偏移。引入社会、经济数据分析,人口增长、经济发展是流域耕地增加进而导致系列土地利用变化的主要人文驱动力,而生态环境保护等宏观政策是流域林地变化的主要驱动力。 相似文献
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94.
为探索乡村人居环境质量的演变规律,该研究综合运用遥感影像、兴趣点、统计数据等多源数据,从生产空间、生活空间、生态空间3个维度构建了乡村人居环境质量评价指标体系,采用熵值法、综合指数法和GIS空间分析对2010—2020年洞庭湖区乡村人居环境质量开展了动态评价,并利用障碍度模型诊断了主要障碍因子。结果表明:1)2010—2020年洞庭湖区乡村人居环境建设成效明显,但区域之间仍存在较大差异,其人居环境质量综合指数在空间上呈现西南部相对下降,东北部逐渐上升的演变趋势;2)从乡村人居环境系统内部来看,2010—2020年生产空间质量指数稳定上升,较高及以上质量等级县域的分布已从洞庭湖区南部转向东部,空间格局发生较大变化;生活空间质量指数明显提高,呈现由市辖区逐渐向外扩张发展的空间演变规律;生态空间质量指数基本保持不变,空间上呈现顺序为西部地区、东部地区、中部地区梯度递减的分布特征;3)影响洞庭湖区乡村人居环境质量的主要障碍因子为乡村经济活动强度、生物丰富度指数、乡村休闲设施密度、农业机械化水平、乡村电力设施水平、医疗情况和水文指数。研究结果一定程度上充实、丰富了乡村人居环境质量理论成果,同时也为推进洞庭湖区乡村人居环境质量提升和乡村振兴状态监测提供了数据与决策支撑。 相似文献
95.
96.
97.
M. Eriksson H. von Euler E. Ekman K. Nordling J. Häggström J. Johansson 《Journal of veterinary internal medicine / American College of Veterinary Internal Medicine》2009,23(6):1170-1174
Background: Canine pulmonary fibrosis (CPF) occurs most commonly in West Highland White Terriers. The differing incidences of CPF among dog breeds suggest that genetic factors contribute to its pathophysiology. Pulmonary fibrosis in humans is associated with mutations in the gene coding for lung surfactant protein C (SP-C) ( SFTPC ).
Hypothesis/Objectives: To investigate the histopathologic changes and SP-C composition and genetic structure in dogs with CPF.
Animals: Five dogs with PF, 2 dogs with other lung diseases, and 3 healthy dogs.
Methods: Lung tissue from dogs with clinically suspected CPF and 5 control cases was analyzed histopathologically. Bronchoalveolar lavage fluid (BALF) collected postmortem from 3 terriers with histopathologically confirmed pulmonary fibrosis and the 5 controls were analyzed by Western blots, and the exons of SFTPC were sequenced for 2 dogs with PF and 1 dog with other lung disease.
Results: SP-C could not be detected in BALF of 1 dog with PF, although SP-B was present. A mutation was detected in SFTPC exon 5 of this dog. From 2 dogs with PF and in all 5 control dogs SP-B and SP-C were detected in BALF.
Conclusions: Taken together, the results indicate that canine and human lung fibrosis share histopathologic features and that analysis of SP-C and its gene in a larger set of dogs with PF is warranted. 相似文献
Hypothesis/Objectives: To investigate the histopathologic changes and SP-C composition and genetic structure in dogs with CPF.
Animals: Five dogs with PF, 2 dogs with other lung diseases, and 3 healthy dogs.
Methods: Lung tissue from dogs with clinically suspected CPF and 5 control cases was analyzed histopathologically. Bronchoalveolar lavage fluid (BALF) collected postmortem from 3 terriers with histopathologically confirmed pulmonary fibrosis and the 5 controls were analyzed by Western blots, and the exons of SFTPC were sequenced for 2 dogs with PF and 1 dog with other lung disease.
Results: SP-C could not be detected in BALF of 1 dog with PF, although SP-B was present. A mutation was detected in SFTPC exon 5 of this dog. From 2 dogs with PF and in all 5 control dogs SP-B and SP-C were detected in BALF.
Conclusions: Taken together, the results indicate that canine and human lung fibrosis share histopathologic features and that analysis of SP-C and its gene in a larger set of dogs with PF is warranted. 相似文献
98.
T.C. Jackson B. Debey S. Lindbloom-Hawley B.T. Jones T. Schermerhorn 《Journal of veterinary internal medicine / American College of Veterinary Internal Medicine》2009,23(2):383-387
Background: Insulinoma is an autonomous insulin-secreting islet cell neoplasm that is rarely diagnosed in cats. The clinical and pathological aspects of feline insulinoma have been described previously, but the molecular characteristics of these tumors have not been investigated.
Objectives: The study objectives were to characterize peptide hormone production and determine expression of selected genes involved in glucose metabolism and insulin secretion in a feline insulinoma.
Methods: Immunohistochemistry and RT-PCR were used to examine hormone and gene expression, respectively, by insulinoma cells.
Results: Immunohistochemistry examination indicated that the tumor cells expressed insulin, chromogranin A, and somatostatin but not glucagon or pancreatic polypeptide. The tumor expressed several genes characteristic of pancreatic beta cells (β cells) including insulin ( INS ), glucose transporter 2 ( GLUT2 ), and glucokinase ( GCK ). The tumor also expressed hexokinase 1 ( HK1 ), a glycolytic enzyme not normally expressed in β cells. GCK expression was higher in the insulinoma than in normal pancreas from the same cat. The GCK : HK1 ratio was >20-fold higher in insulinoma tissue than in normal pancreas.
Conclusions and Clinical Importance: The feline insulinoma produced several peptide hormones and expressed genes consistent with a β-cell phenotype. The pattern of hexokinase gene expression in tumor cells differed from that of normal pancreas. These findings suggest insulinoma cells may have an increased sensitivity to glucose that could contribute to the abnormal insulin secretory response observed at low serum glucose concentrations. 相似文献
Objectives: The study objectives were to characterize peptide hormone production and determine expression of selected genes involved in glucose metabolism and insulin secretion in a feline insulinoma.
Methods: Immunohistochemistry and RT-PCR were used to examine hormone and gene expression, respectively, by insulinoma cells.
Results: Immunohistochemistry examination indicated that the tumor cells expressed insulin, chromogranin A, and somatostatin but not glucagon or pancreatic polypeptide. The tumor expressed several genes characteristic of pancreatic beta cells (β cells) including insulin ( INS ), glucose transporter 2 ( GLUT2 ), and glucokinase ( GCK ). The tumor also expressed hexokinase 1 ( HK1 ), a glycolytic enzyme not normally expressed in β cells. GCK expression was higher in the insulinoma than in normal pancreas from the same cat. The GCK : HK1 ratio was >20-fold higher in insulinoma tissue than in normal pancreas.
Conclusions and Clinical Importance: The feline insulinoma produced several peptide hormones and expressed genes consistent with a β-cell phenotype. The pattern of hexokinase gene expression in tumor cells differed from that of normal pancreas. These findings suggest insulinoma cells may have an increased sensitivity to glucose that could contribute to the abnormal insulin secretory response observed at low serum glucose concentrations. 相似文献
99.
Joo Youn Oh † ‡ Mee Kum Kim † ‡ Hyun Ju Lee † ‡ Jung Hwa Ko † ‡ Won Ryang Wee † ‡ Jin Hak Lee † ‡ 《Veterinary ophthalmology》2009,12(S1):50-56
Objective Although variations exist between species with respect to outcomes after cryopreservation, little is known about the differences in the susceptibility of the corneal stroma to cryoinjury. We performed this study to investigate freeze–thaw-induced damage in keratocytes and collagen in rabbit, pig, and human corneas.
Animals studied Rabbit, pig, and human.
Procedures We prepared 250-μm-thick anterior stroma from rabbit, pig, and human corneas after scraping off the epithelium and endothelium. Each 250-μm-thick corneal stroma without epithelium was placed in a 50-mL tube, frozen with liquid N2 for 15 min and taken out to thaw rapidly at 37 °C. This procedure of rapid freezing and thawing was repeated three times. Differences between the species with respect to cells and collagen structures were examined using hematoxylin–eosin (H&E) staining, terminal deoxynucleotidyl transferase-mediated nick end labeling (TUNEL) assay, and transmission electron microscopy (TEM). We orthotopically transplanted the pig and rabbit corneal transplants after the triple freeze–thaw cycle into rabbit eyes and evaluated graft survival.
Results On gross examination, rabbit corneas became opaque after the triple freeze–thaw procedure, while pig and human corneas remained transparent. Histologically, keratocytes were apoptotic on TUNEL assay and TEM in rabbit, pig, and human corneas. Collagen fibrils were fragmented and the arrangement of collagen fibrils was severely disturbed in rabbit corneas on H&E staining and TEM; collagen was well preserved in pig and human corneas. Rabbit corneal stroma underwent autolysis after transplantation, whereas the pig corneal stroma remained clear for 1 month.
Conclusions Our study showed that rabbit corneal stroma was more susceptible to freeze–thaw injury than pig and human corneas. 相似文献
Animals studied Rabbit, pig, and human.
Procedures We prepared 250-μm-thick anterior stroma from rabbit, pig, and human corneas after scraping off the epithelium and endothelium. Each 250-μm-thick corneal stroma without epithelium was placed in a 50-mL tube, frozen with liquid N
Results On gross examination, rabbit corneas became opaque after the triple freeze–thaw procedure, while pig and human corneas remained transparent. Histologically, keratocytes were apoptotic on TUNEL assay and TEM in rabbit, pig, and human corneas. Collagen fibrils were fragmented and the arrangement of collagen fibrils was severely disturbed in rabbit corneas on H&E staining and TEM; collagen was well preserved in pig and human corneas. Rabbit corneal stroma underwent autolysis after transplantation, whereas the pig corneal stroma remained clear for 1 month.
Conclusions Our study showed that rabbit corneal stroma was more susceptible to freeze–thaw injury than pig and human corneas. 相似文献
100.
C. W. Schmiedt J. A. Grimes G. Holzman J. F. McAnulty 《Veterinary and comparative oncology》2009,7(1):45-53
The objective of this retrospective study is to report and analyse the incidence of and risk factors for post-transplant malignant neoplasia (PTMN) in feline renal transplant recipients (cases, n = 45) and compare incidence to a population of cats that did not receive a transplant (controls, n = 79). Information from the medical records of cases regarding signalment, blood work and concomitant disease, post operative cyclosporine concentrations, survival time (ST), and whether PTMN developed, the type of PTMN, time to occurrence (TTO), and ST after diagnosis was gathered. PTMN occurred in 11 of 45 (24%) cases, of which, four were lymphoma. Median TTO of all PTMN was 1020 days. Median TTO of lymphoma was 454 days. Median ST after diagnosis of PTMN was 15 days. No risk factors were identified. Compared with control cats, cases had more than six times higher odds of developing PTMN compared with control cats ( P < 0.01). 相似文献