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101.
LEANDRO DA S. DUARTE MELINA M. G. DOS‐SANTOS SANDRA M. HARTZ VALRIO DEPATTA PILLAR 《Austral ecology》2006,31(4):520-528
Abstract Araucaria Forest expansion over grassland takes place under wet climate conditions and low disturbance and it is hypothesized that isolated trees established on grassland facilitate the establishment of forest woody species beneath their canopies. Forest with Araucaria angustifolia is a particular type of Brazilian Atlantic Forest and the main forest type on the highland plateau in south Brazil, often forming mosaics with natural Campos grassland. The objectives of this paper were to evaluate the role of isolated shrubs and trees as colonization sites for seedlings of Araucaria Forest woody species on grassland, to determine which species function as preferential nurse plants in the process and the importance of vertebrate diaspore dispersal on the structure of seedling communities beneath nurse plants. The study was conducted in São Francisco de Paula, Rio Grande do Sul State, where we sampled isolated shrubs and trees in natural grassland near Araucaria Forest edges. Seedlings were counted and identified, and seedling diaspore dispersal syndromes, size and colour were registered. We detected 11 woody species with a potential role in nucleating grassland colonization by forest species. Beneath the canopies of nurse plants more forest species seedlings were found compared with open field grassland and the seedlings had diaspores mostly dispersed by vertebrates. Also, more seedlings were found under the canopy of A. angustifolia than beneath other nurse plant species. We conclude that A. angustifolia trees established on grassland act as nurse plants, by attracting disperser birds that promote colonization of the site by other forest species seedlings, and that under low level of grassland disturbance, conservation of frugivorous vertebrate assemblages may increase forest expansion over natural grassland and also facilitate the regeneration of degraded forest areas. 相似文献
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Granov AM Gorelov AI Shumskiĭ IA Polikarpov AA Shkol'nik MI Vorob'ev MI Karelin MI 《Vestnik rentgenologii i radiologii》1999,(6):20-23
The authors analyse the long-term results of treatment of 106 patients with advanced renal cell carcinoma. The patients were divided in two groups. Group 1 (42 patients) included cases with single metastatic lesion. Patients of group 2 (n = 64) had more than one site of metastases. All patients were treated by nephrectomy, embolization with chemotherapeutic agent or arterial occlusion without cytostatic drug except nine patient of group 2, who has undergone chemo and hormonal therapy. The survival according to method at treatment was studies. After occlusion satisfactory results were obtained in cases with single metastasis lesion and also in cases with many sites of metastases. Oily chemoembolization in renal cell carcinoma with distant metastases has given better results as compared with the embolization without chemodrugs. We conclude that endovascular method of treatment is an alternative to the traditional nephrectomy in palliation of renal cell carcinoma. 相似文献
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Granov AM Tiutin LA Ryzhkova DV Kostenikov NA Fadeev NP Savello VE Pavlovskiĭ AV Tlostanova MS Efimenko AV Stanzhevskiĭ AA 《Vestnik rentgenologii i radiologii》2002,(2):18-22
The paper examines the informational value of positron emission tomography (PET) using 18FDG in the diagnosis of malignant of neoplasms of the pancreas and in the estimation of the extent of a metastatic involvement. Forty-four patients (26 males and 18 females whose age ranged from 28 to 60 years) with histologically verified cancer of the pancreas were examined. The study was conducted in the whole body mode on an Ecat Exact 47 positron emission tomograph following 70-90 minutes of administration of 18FDG, 370-420 MBk. To assess the findings, the differential accumulation ratio (DAR) of formation/liver was calculated. The mean DAR in patients with benign and malignant pancreatic tumors was 1.17 +/- 0.064 and 4.90 +/- 0.3 (p < 0.05). There was a false positive case in a patient with an exacerbation of chronic pancreatitis in the study. A relationship was observed between the level of tumor tissue 18FDG capture and the degree of malignancy. PET scanning in the whole body mode estimates the extent of a tumorous process. The authors' data show that the liver was most commonly involved in a metastatic process (96.6%). Hence, 18FDG PET is a highly informative technique in the diagnosis of malignant pancreatic tumors and in the estimation of the extent of a metastatic process and permits a differential diagnosis between benign and malignant tumors. 相似文献
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Current information on the structure and function of motile tubular vacuoles in Pisolithus tinctorius and other fungi is reviewed. The use of fluorochromes to label the vacuole lumen is evaluated and observations on the structure and motility of vacuoles in P. tinctorius are differentiated from possible artifacts. The styryl dyes FM4-64 and MDY-64, used in yeast to demonstrate endocytosis, show little or no labeling of internal membranes in undamaged P. tinctorius cells. This agrees with our data showing that other probes for endocytosis such as Lucifer yellow CH are not taken up by hyphal tip cells. Overall, the observations do not support endocytosis in hyphal tips. It has been suggested that tubular vacuole systems carry out longitudinal transport, and evidence in favor of this hypothesis is evaluated. New data are presented to show that many of the large vacuoles in subapical cells are attached to the plasma membrane and are relatively immobile, while video sequences show movement of fluorochrome in pulses along a series of several large vacuoles, all interconnected via tubules. Tubular vacuoles from thick sections of hyphae processed under anhydrous conditions are shown by X-ray microanalysis to contain relatively high levels of P and K, as seen previously in the larger vacuoles. These results provide further evidence for a role of the tubular vacuoles in longitudinal transport of P. Copyright 1998 Academic Press. 相似文献
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Erythropoietin(EPO) is the major regulator of mamalian erythropoisis,which stimulates the growth and differentiation of hematopoietic cells through interaction with its receptor(EPO-R),Here we use HEL cells (a human erythro-leukemia cell line) as a model to elucidate the pathway of signal transduction in the EPO-induced HEL cells.Our data show that the EPOR (EPO receptor) on the surface of HEL cells interacts with the Janus tyrosine protein kinase(Jak2) to transduce intracellular signals through phosphorylation of cytoplasmic proteins in EPO-treated HEL cells.Both STAT1 and STAT5 in this cell line are tyrosine-phosphorylated and translocated to nucleus following the dinding of EPO to HEL cells.Furthermore,the dinding of both STAT1 and STAT5 proteins to specific DNA elements(SIE and PIE elements) is revealed in an EPO-dependent manner,Our data demonstrate that the pathway of signal transduction following the binding of EPO to HEL cells is similar to immature eryhroid cell from the spleen of mice infected with anemia strain of Friend virus. 相似文献
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Effect of Ethidium Bromide on the Oxidative Metabolism and Enzyme Profiles of Crithidia fasciculata*
SYNOPSIS. Changes in the metabolism of Crithidia fasciculata ATCC 11745 when grown in the presence of ethidium bromide were studied. Ethidium bromide-grown cells had decreased respiratory activity as measured by oxygen consumption. More than 50% of the organisms cultivated in a defined medium containing 1.0 mg/liter of ethidium bromide became dyskine-toplastic and had decreased activities of particulate succinate and NADH-linked dehydrogenases as well as of soluble isocitrate dehydrogenase. These cells also had increased activities of particulate α-glycerophosphate dehydrogenase, soluble α-glycerophosphate dehydrogenase, malic enzyme, hexokinase, and malate dehydrogenase. Ethidium bromide-grown cells had a lower level of ATP and contained less DNA than cells grown in its absence. 相似文献