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21.
Robson Sartorello Alexandre Budu Piero Bagnaresi Carlos AH Fernandes Paloma M. Sato Vânia B. Bueno Marcos RM Fontes Pedro L. Oliveira Gabriela O. Paiva‐Silva Simone V. Alves Luis ES Netto Luiz H. Catalani Celia RS Garcia 《Cell biology international》2010,34(8):859-865
The cellular traffic of haem during the development of the human malaria parasite Plasmodium falciparum, through the stages R (ring), T (trophozoite) and S (schizonts), was investigated within RBC (red blood cells). When Plasmodium cultures were incubated with a fluorescent haem analogue, ZnPPIX (Zn protoporphyrin IX) the probe was seen at the cytoplasm (R stage), and the vesicle‐like structure distribution pattern was more evident at T and S stages. The temporal sequence of ZnPPIX uptake byP. falciparum‐infected erythrocytes shows that at R and S stages, a time‐increase acquisition of the porphyrin reaches the maximum fluorescence distribution after 60 min; in contrast, at the T stage, the maximum occurs after 120 min of ZnPPIX uptake. The difference in time‐increase acquisition of the porphyrin is in agreement with a maximum activity of haem uptake at the T stage. To gain insights into haem metabolism, recombinant PfHO (P. falciparum haem oxygenase) was expressed, and the conversion of haem into BV (biliverdin) was detected. These findings point out that, in addition to haemozoin formation, the malaria parasite P. falciparum has evolved two distinct mechanisms for dealing with haem toxicity, namely, the uptake of haem into a cellular compartment where haemozoin is formed and HO activity. However, the low Plasmodium HO activity detected reveals that the enzyme appears to be a very inefficient way to scavenge the haem compared with the Plasmodium ability to uptake the haem analogue ZnPPIX and delivering it to the food vacuole. 相似文献
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Background
During sexual transmission of HIV in women, the virus breaches the multi-layered CD4 negative stratified squamous epithelial barrier of the vagina, to infect the sub-epithelial CD4 positive immune cells. However the mechanisms by which HIV gains entry into the sub-epithelial zone is hitherto unknown. We have previously reported human mannose receptor (hMR) as a CD4 independent receptor playing a role in HIV transmission on human spermatozoa. The current study was undertaken to investigate the expression of hMR in vaginal epithelial cells, its HIV gp120 binding potential, affinity constants and the induction of matrix metalloproteinases (MMPs) downstream of HIV gp120 binding to hMR.Principal Findings
Human vaginal epithelial cells and the immortalized vaginal epithelial cell line Vk2/E6E7 were used in this study. hMR mRNA and protein were expressed in vaginal epithelial cells and cell line, with a molecular weight of 155 kDa. HIV gp120 bound to vaginal proteins with high affinity, (Kd = 1.2±0.2 nM for vaginal cells, 1.4±0.2 nM for cell line) and the hMR antagonist mannan dose dependently inhibited this binding. Both HIV gp120 binding and hMR exhibited identical patterns of localization in the epithelial cells by immunofluorescence. HIV gp120 bound to immunopurified hMR and affinity constants were 2.9±0.4 nM and 3.2±0.6 nM for vaginal cells and Vk2/E6E7 cell line respectively. HIV gp120 induced an increase in MMP-9 mRNA expression and activity by zymography, which could be inhibited by an anti-hMR antibody.Conclusion
hMR expressed by vaginal epithelial cells has high affinity for HIV gp120 and this binding induces production of MMPs. We propose that the induction of MMPs in response to HIV gp120 may lead to degradation of tight junction proteins and the extracellular matrix proteins in the vaginal epithelium and basement membrane, leading to weakening of the epithelial barrier; thereby facilitating transport of HIV across the vaginal epithelium. 相似文献24.
Adipose tissue-derived stem cells (ADSCs) are one population of adult stem cells that can self renew and differentiate into
multiple lineages. Because of advantages in method and quantity of acquisition, ADSCs are gaining attention as an alternative
source of bone marrow mesenchymal stem cells. In this study, we performed microRNA profiling of undifferentiated and of neurally-differentiated
ADSCs to identify the responsible microRNAs in neurogenesis using this type of stem cell. MicroRNAs from four different donors
were analysed by microarray. Compared to the undifferentiation control, we identified 39–101 microRNAs with more than two-fold
higher expression and 3–9 microRNAs with two-fold lower expression. The identified microRNAs were further analysed in terms
of gene ontology (GO) in relation with neurogenesis, based on their target mRNAs predicted by computational analysis. This
study revealed the specific microRNAs involved in neurogenesis via microRNA microarray, and may provide the basic information
for genetic induction of adult stem cell differentiation using microRNAs. 相似文献
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The glucose transport system of the hyperthermophilic anaerobic bacterium Thermotoga neapolitana 总被引:1,自引:1,他引:0
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The glucose transport system of the extremely thermophilic anaerobic bacterium Thermotoga neapolitana was studied with the nonmetabolizable glucose analog 2-deoxy-D-glucose (2-DOG). T. neapolitana accumulated 2-DOG against a concentration gradient in an intracellular free sugar pool that was exchangeable with external source of energy, such as pyruvate, and was inhibited by arsenate and gramicidin D. There was no phosphoenolpyruvate-dependent phosphorylation of glucose, 2-DOG, or fructose by cell extracts or toluene-treated cells, indicating the absence of a phosphoenolpyruvate:sugar phosphotransferase system. These data indicate that D-glucose is taken up by T. neapolitana via an active transport system that is energized by an ion gradient generated by ATP, derived from substrate-level phosphorylation. 相似文献
27.
Fucosylated protein of retinal cone photoreceptor outer segments: morphological and biochemical analyses
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Cone outer segments (OS) of the goldfish retina are diffusely labeled after intravitreal injection of [(3)H]fucose while rod OS remain unlabeled. By electron microscopic radioautography, the OS of red- and blue-sensitive cones are heavily labeled while green- sensitive cone OS are lightly labeled. The time-course and pattern of OS labeling in all cone types from 30 min to 24 h resemble that of incorporation of other sugars into rhodopsin in rod OS. The nature of the cone OS-specific fucosylated component(s) was examined using biochemical techniques. Cone OS were prelabeled by intravitreal injection of [(3)H]fucose 24 h before sacrifice. Photoreceptor OS were isolated using a discontinuous sucrose density gradient and it was verified by electron microscopic radioautography that the only source of radioactivity in the preparations was cone OS. The different cone types could be recognized by the heaviness of labeling, characteristic membrane spacing, and 'staining' of green cone OS in vitro with horseradish peroxidase. After acid hydrolysis of prelabeled photoreceptor membranes, 90 percent of the counts were in the neutral sugar fraction which was analyzed by thin-layer chromatography. Approximately 70 percent of the radioactivity co-chromatographed with authentic fucose. SDS-PAGE/fluorography of prelabeled photoreceptor membranes revealed a single radioactive component that was lightly stained with coomassie blue and showed an apparent molecular weight of 33,000. This cone-derived band was separated from unlabeled rod opsin which was well stained and showed an apparent mol wt of 38,000. Isoelectric focusing under denaturing conditions produced two major and one minor band of radioactivity with isoelectric points of 8.2, 8.6, and 8.8 respectively. No radioactivity was found in association with a stained band corresponding in isoelectric point to that of bovine opsin (pl, 6.2). The fucosylated component was readily digested by pronase, indicating its protein nature. Washing of the isolated OS with isotonic and hypotonic buffers failed to extract major amounts of the radioactivity, suggesting that the fucosylated component is an integral membrane protein. The presence of a fucosylated protein thus represents a major difference between cone and rod OS in the goldfish and has enabled us to identify cone OS in preparations of isolated photoreceptor membranes and to demonstrate the separation of a cone-derived glycoprotein from rod opsin. 相似文献
28.
Elrasheid AH Kheirelseid Kah Hoong Chang John Newell Michael J Kerin Nicola Miller 《BMC molecular biology》2010,11(1):12
Background
Gene expression analysis has many applications in cancer diagnosis, prognosis and therapeutic care. Relative quantification is the most widely adopted approach whereby quantification of gene expression is normalised relative to an endogenously expressed control (EC) gene. Central to the reliable determination of gene expression is the choice of control gene. The purpose of this study was to evaluate a panel of candidate EC genes from which to identify the most stably expressed gene(s) to normalise RQ-PCR data derived from primary colorectal cancer tissue. 相似文献29.
Ashraf A Helmy Mostafa A Hamad Ahmed M Aly Tahra Sherif Mostafa Hashem Dalia AH El-Sers Mohammad Semieka 《Annals of surgical innovation and research》2011,5(1):1-9
Background
Biliary tract reconstruction continues to be a challenging surgical problem. Multiple experimental attempts have been reported to reconstruct biliary defects with different materials and variable outcome. Our aim was to evaluate a new method for biliary reconstruction using an isolated pedicled gastric tube in a live animal trial and also to present the first clinical case.Methods
Seven mongrel dogs underwent biliary reconstruction using gastric tube harvested, completely separated from the greater curvature, and based on a vascularized pedicle with the right gastroepiploic vessels. The tube was interposed between the common bile duct (CBD) and the duodenum. Postoperative mortality, morbidity, liver functions, gross and microscopic histological picture were assessed. The first clinical case was also presented where, in a patient with post-cholecystectomy biliary injury, an isolated pedicled gastric tube was interposed between the proximal and distal ends of the CBD.Results
One dog did not recover from anesthesia and another one died postoperatively from septic peritonitis. Five dogs survived the procedure and showed uneventful course and no cholestasis. The mean anastomotic circumference was 4.8 mm (range 4-6) for CBD anastomosis and 6.2 mm (range 5-7) for duodenal anastomosis. Histologically, anastomotic sites showed good evidence of healing. In the first clinical case, the patient showed clinical and biochemical improvement. Endoscopic retrograde cholangiography was feasible and assured patent biliary anastomoses.Conclusion
In mongrel dogs, biliary reconstruction using pedicled gastric tube interposition between CBD and duodenum is feasible with satisfactory clinical results, anastomotic circumference and histological evidence of healing. The technique is also feasible in human and seems to be promising. 相似文献30.
Jo Moore Stephen AC Hawkins Anthony R Austin Timm Konold Robert B Green Ian W Blamire Ian Dexter Michael J Stack Melanie J Chaplin Jan PM Langeveld Marion M Simmons Yvonne I Spencer Paul R Webb Michael Dawson Gerald AH Wells 《BMC research notes》2011,4(1):1-13