排序方式: 共有32条查询结果,搜索用时 190 毫秒
11.
《Biotechnic & histochemistry》2013,88(7):477-485
We investigated the immunoexpression of the intermediate filament proteins, cytokeratin and desmin, and the morphological changes in the liver of rats during experimental fasciolosis at 4, 7 and 10 weeks post-infection. Rats were infected with 30 Fasciola hepatica metacercariae. Paraffin sections of the liver were stained using H & E, PAS and azan stains. Immunohistochemical reactions were performed using antibodies against cytokeratin and desmin. The experimental F. hepatica infection led to fibrosis and cirrhosis of the liver, and to inflammation of the common bile ducts. The expression of cytokeratin was increased in the epithelial cells of both the liver bile ductules at 4, 7 and 10 weeks post-infection and in the common bile ducts at 7 and 10 weeks post-infection compared to uninfected rats; expression in the common bile ducts was more intense. The myofibroblasts of the liver and smooth myocytes of the interlobular bile ducts and common bile ducts, showed a slight increase in desmin expression compared to the uninfected rats. The increased expression of cytokeratins in the hyperplastic rat common bile duct epithelium during the biliary phase of fasciolosis at 7 and 10 weeks post-infection may be explained by mechanical irritation by the parasite and an inflammatory reaction in the bile duct epithelium and in periductal fibrous tissue. 相似文献
12.
13.
Meunier C Tirard C Hurtrez-Boussès S Durand P Bargues MD Mas-Coma S Pointier JP Jourdane J Renaud F 《Molecular ecology》2001,10(5):1333-1340
Fasciolosis is a re-emerging parasitic disease that affects an increasing number of people in developing countries. The most severe endemic affects the Bolivian Altiplano, where the liver fluke (Fasciola hepatica) and its hermaphroditic snail host, Lymnaea truncatula, have been introduced from Europe. To achieve a better understanding of the epidemiological situation and the consequences of the colonization event of this invasive species, genetic analysis of Bolivian snail populations was needed. Here we compare the genetic diversity and population structure of snail samples from the Bolivian Altiplano with samples from the Old World at six polymorphic microsatellite loci. Whereas some variability exists in the snail populations from the Old World, we observe only a single genotype of L. truncatula in the Bolivian Altiplano. We discuss the possible explanations for such a reduction in genetic variability, and, given the high natural parasitism pressures exerted on the snail populations, we discuss the relevance of this result for host-parasite interactions. 相似文献
14.
Optimal conditions for activation of adenylate cyclase in membrane particles were studied. Enzyme activation with serotonin (5-hydroxytryptamine), NaF, and guanosine (GTPγS) was time- and temperature-dependent. Mg2+ was required for enzyme activation. Adenylate cyclase that was activated by NaF or GTPγS was gradually inhibited by while enzyme activated with serotonin and GTP responded faster to inhibition by the same sulfhydryl reagent. The enzyme responded in a similar fashion to a spin-labeled analog 3-(maleimidomethyl)-2,2,5,5-tetramethyl-1-pyrolidinyloxyl (i.e., nitroxide). Binding of the spin label was enhanced following enzyme activation by serotonin, NaF, or GTPγS in the presence of Mg2+. Activation of the enzyme was accompanied by an increase in the strong immobilization peaks in the EPR spectra. Both effects, the increase in binding and in the strong immobilization peaks, can be induced by Mg2+ alone. The results indicate that a general conformational change induced by Mg2+ may be essential for adenylate cyclase activation. 相似文献
15.
A single amino acid substitution affects substrate specificity in cysteine proteinases from Fasciola hepatica 下载免费PDF全文
Smooker PM Whisstock JC Irving JA Siyaguna S Spithill TW Pike RN 《Protein science : a publication of the Protein Society》2000,9(12):2567-2572
The trematode Fasciola hepatica secretes a number of cathepsin L-like proteases that are proposed to be involved in feeding, migration, and immune evasion by the parasite. To date, six full cDNA sequences encoding cathepsin L preproproteins have been identified. Previous studies have demonstrated that one of these cathepsins (L2) is unusual in that it is able to cleave substrates with a proline in the P2 position, translating into an unusual ability (for a cysteine proteinase) to clot fibrinogen. In this study, we report the sequence of a novel cathepsin (L5) and compare the substrate specificity of a recombinant enzyme with that of recombinant cathepsin L2. Despite sharing 80% sequence identity with cathepsin L2, cathepsin L5 does not exhibit substantial catalytic activity against substrates containing proline in the P2 position. Molecular modeling studies suggested that a single amino acid change (L69Y) in the mature proteinases may account for the difference in specificity at the S2 subsite. Recombinant cathepsin L5/L69Y was expressed in yeast and a substantial increase in the ability of this variant to accommodate substrates with a proline residue in the P2 position was observed. Thus, we have identified a single amino acid substitution that can substantially influence the architecture of the S2 subsite of F. hepatica cathepsin L proteases. 相似文献
16.
17.
Jae-Hak Park Meliton N. Novilla Juha Song Kyung-Sul Kim Seo-Na Chang Ju-Hee Han Byung Hee Lee Do-Hun Lee Hyun-Mac Kim Young-Ha Kim Hee-Jeong Youn Jihyon Kil 《The Korean journal of parasitology》2014,52(5):527-529
This study reports the first case of Capillaria hepatica infection in a nutria in Korea. Ten nutrias, captured near the Nakdong River, were submitted to our laboratory for necropsy. White-yellowish nodules were found in the liver of 1 of the nutrias at necropsy. Histologically, the lesions were granulomatous, and infiltrations of lipid-laden macrophages, eosinophils, and several multinucleated giant cells were observed. The lesions consisted of numerous eggs and necrotic hepatocytes. The eggs were lemon-shaped and had polar plugs at the ends of both long sides. The eggs were morphologically identified as those of C. hepatica. Worldwide, C. hepatica infection in nutrias is very rare. Nutrias are a kind of livestock, as well as wildlife; therefore, an epidemiological study for parasitic infections needs to be conducted. 相似文献
18.
I. Fairweather H.R. Anderson L.T. Threadgold 《International journal for parasitology》1988,18(8):1061-1069
Fasciola hepatica: morphological changes in vitelline cells following treatment in vitro with the deacetylated (amine) metabolite of diamphenethide (DAMD). International Journal for Parasitology 18: 1061–1069. The effect of the deacetylated (amine) metabolite of diamphenethide (DAMD, 10 μg ml−1) on the vitelline cells of Fasciola hepatica over an 18 h period in vitro has been determined by transmission electron microscopy. DAMD acts preferentially on the undifferentiated stem cells and the intermediate cells in the early stages of protein synthesis; it appears to prevent their continued development. In the stem cell the nucleolus is absent after 6 h. During the rest of the drug treatment period considerable clumping of heterochromatin takes place, the cells round up and become electron-dense. Signs of autophagy are also evident, and the mitochondria become swollen and disorganized. From 6 h onwards there are progressive changes in the It1 (intermediate type 1) cells, including clumping of the heterochromatin in the nucleus, a decrease in the number of egg-shell globules (and consequently a reduction in the number and size of the shell globule clusters), and a decrease in the number of ribosomes on the GER cisternae, although the GER system remains well-developed. By 18 h the nucleolus is absent, and the cells are very rounded and electron-dense; the mitochondria are swollen and disorganized. Similar changes are evident in the It2 (intermediate type 2) cells, so that by 18 h it is difficult to distinguish between the It1 and It2 cells. In the mature cells there is a progressive decrease in the number and size of the shell globule clusters from 9 h onwards. Glycogen synthesis and ‘yolk’ formation may also be impaired and lipid droplets are present. Spaces begin to appear between the nurse cell cytoplasm and the vitelline cells after 9 h, and disruption of the nurse cell cytoplasm is evident after 12 h, becoming very severe by 18 h. By this time the follicle is very disorganized and empty-looking. In more severely affected follicles the mature cells are seen to be breaking down. Over the 18 h drug treatment period, a change in the cell population of the follicle takes place, with relatively more stem, early It1 and mature cells being present, whilst few if any characteristic It1 and It2 cells remain. The results are interpreted as being due to an inhibition of protein synthesis in the vitelline cells by DAMD. 相似文献
19.
20.