126,878 research outputs found
Characterisation of the oxidoreductase Erol-Lß and the misfolding of the secretory pathway substrate HLA-B27
No full textThe endoplasmic reticulum (ER) is the site of oxidative folding for proteins entering the secretory pathway. Here, nascent polypeptides acquire disulfide bonds, which confer both stability and functionality on secretory and ER-resident proteins. In eukaryotes, this process is catalysed by the disulfide oxidoreductase protein disulfide isomerase (PDI). Many mammalian homologs of PDI have been described including the pancreas-specific homolog PDIp. PDI is 'recharged' by the disulfide oxidoreductase Его. Accepted electrons are then passed to molecular oxygen via an Ero-bound flavin adenine dinucleotide (FAD) molecule. We provide data showing that human Erol-Lß protein is able to form disulfide-dependent homodimers in vivo. We also provide evidence that the yeast G252S and H254Y FAD- binding mutants exhibit reduced affinity for PDI. Since the Erol-La C391A mutant can rescue the erol-l temperature-sensitive mutant, Ero-PDI association and Ero-Ero dimensation may be significant in maintaining the oxidative protein folding pathway in the ER. Homodimerisation was not affected by FAD-binding mutants, suggesting that the erol-1 and erol-2 phenotypes cannot be accredited to the failure of Erol p to homodimerise. We also make the first steps towards characterising the interactions of PDIp with the human Erol-La and Erol-Lß proteins. In order to observe protein-protein interactions, we characterise a polyclonal anti֊Erol֊Lß antibody for intended use in immunoprecipitations and immunoblotting. Quality control measures are in place to ensure that only natively folded proteins are permitted to exit the secretory pathway. Chaperone molecules such as immunoglobulin- binding protein (BiP) retain unfolded or misfolded proteins in the ER， which are eventually retrotranslocated out of the ER and degraded. When misfolded proteins accumulate in the ER， however, the folding capacity of the ER may be exceeded. This triggers a cellular response pathway called the unfolded protein response, aimed at restoring homeostasis in the ER via transcription regulation and translational attenuation. We provide evidence that misfolding/misoxidation of the major histocompatability complex (MHC) class I heavy chain HLA-B27 in HeLa cells causes the UPR to be triggered. Possession of the HLA-B27 allele in lymphoblastoid cell lines results in some UPR signalling. Interestingly, analysis of IREI-mediated XBPl splicing shows a distinct difference in sensitivity of the UPR to induction by the pharmacological agents dithiothreitol (DTT) and tunicamycin. Since possession of HLA-B27 is highly associated with development of the chronic inflammatory disease ankylosing spondylitis, induction of the UPR as a consequence of HLA-B27 misfolding may have implications in disease pathogenesis
Characterising the expression and interactions of the Endoplasmic Reticulum Oxidoreductase Erol β
No full textProteins destined for the secretory pathway and endoplasmic reticulum (ER) resident proteins are targeted to the ER through an N-terminal signal sequence. Proteins then follow a post-translational maturation process to fold into functional proteins. For most of these proteins the formation of disulfide bonds (S-S) at the correct position is essential for structure and function. In eukaryotes, protein oxidation in the ER is catalysed by Endoplasmic reticulum oxidoreductases (EROs) which donate disulfide bonds to (and accept electrons from) Protein Disulfide Isomerase (PDI). In yeast, Erol p is essential for viability and protein secretion. Two ER resident homologues have been identified in the human genome, Erolα and Erol β, which complement the yeast erol-1 temperature sensitive mutation. The main focus of this project was Erol β. Under steady state conditions in transfected cells, Ero 1 β was captured in higher molecular weight complexes in the presence and in the absence of an alkylating agent. Ero-PDI covalent interactions are alkylation dependent, but alkylation independent Ero Iß complexes were found in transfected cells and endogenous tissue. In Erolα the CXXCXXC C-terminal motif is important for protein folding, structural integrity and complex formation with the PDI. In Ero Iß, the AXXCXXC (C390A) mutation disrupts covalent PDI interactions but does not interfere with homodimer formation. The CXXCXXA (C396A) mutation caused disruption of Ero Iß homodimer formation. Modelling the dimer onto the Erol p crystal structure suggested that this 396 cysteine is indirectly disrupting dimmer formation by most likely displacing the cofactor FAD. Two FAD binding domain mutants, initially discovered in yeast, were constructed in Ero Iß and were found to cause instability of Ero Iß through misoxidation during temperature and reducing stress conditions. Ero Iß expression patterns were studied using immunohistochemistry on human stomach and pancreas tissues. The data indicated that Ero Iß is constitutively strongly expressed in enzyme producing chief cells and hormone producing pancreatic islet cells. An interesting result from immunohistochemistry stainings of healthy, Barrett's and oesophageal tumour tissue showed that the ER chaperone protein ERp57 is up-regulated only ill dysplastic and oesophageal tumour tissue. These initial findings suggest ERp57 has potential as a marker in oesophageal tumour diagnosis
Going Beyond Counting First Authors in Author Co-citation Analysis
No full textThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Use of continuous horizontal mattress suture techniques in microsurgery: An experimental study in rats
No full textPurpose: The purpose of this study was to determine whether the continuous horizontal mattress suture technique can replace the continuous simple suture technique and to compare the results with other microvascular suture procedures. Methods: Sixty-four femoral arteries of 32 Sprague-Dawley rats were used in this study. The animals were divided equally into 4 groups with 16 anastomoses in each group. The arteries (6.8-1.0 mm diameter) were anastomosed by using the continuous horizontal mattress suture technique in group I, interrupted horizontal mattress suture technique in group II, simple interrupted suture technique in group III, and simple continuous suture technique in group IV. At the end of the anastomosis time, leakage, and patency were assessed and graded in all groups. On the 14th day after surgery the rats were killed and 5 patent specimens from each group were examined under light microscopy for histology. One specimen from each group was prepared for scanning of the endothelial surface under electron scanning microscopy. Results: Group I anastomoses were performed the most quickly. Groups I and III anastomoses had 100% patency rates. Under light microscopy the edge eversion was apparent consistently and under electron microscopy all endothelial surfaces were intact and no suture material was seen in groups I and II. In group III some suture material was covered by endothelial cells and lumen surfaces were torn; endothelization also was rough compared with groups I and II. In group IV suture material was seen in the lumen because of a loose suture knot. The endothelium also was not regular. Conclusions: The horizontal mattress suturing technique is the only technique in which the suture material never contacts the lumen. Continuous horizontal mattress suture technique is superior to the other microvascular procedures and is the safest and fastest procedure for microvascular anastomosis in rats
Dispelling the Myths Behind First-author Citation Counts
No full textWe conducted a full-scale evaluative citation analysis study of scholars in the XML research field to explore just how different from each other author rankings resulting from different citation counting methods actually are, and to demonstrate the capability of emerging data and tools on the Web in supporting more realistic citation counting methods. Our results contest some common arguments for the continued
use of first-author citation counts in the evaluation of scholars, such as high correlations between author rankings by first-author citation counts and other citation
counting methods, and high costs of using more realistic citation counting methods that are not well-supported by the ISI databases. It is argued that increasingly available digital full text research papers make it possible for citation analysis studies to go beyond what the ISI databases have directly supported and to employ more
sophisticated methods
Anadolu'da bir çınar : Prof. Dr. M. Erol Altınsapan 60. Yaş Armağanı
No full textProf.Dr. Erol Altınsapan 60. Yaş Armağan Kitab
Focal fibrocartilaginous dysplasia in the humerus
No full textFocal fibrocartilaginous dysplasia is an uncommon, benign bone lesion that causes deformity of the long bones in young children. It has most commonly been encountered in the proximal tibia, and very rarely in the long bones of the upper limb, that is, the proximal humerus, distal radius, ulna and proximal phalanx. Only one case of focal fibrocartilaginous dysplasia of the proximal humerus has been reported previously. The present study reports two such additional cases that were diagnosed in late childhood. The clinical presentation and radiographic findings are described with an emphasis on the natural evolution of the disease. Limb-length discrepancy is anticipated in these children in the long-term follow-up and, therefore, surgical intervention should be considered in treatment. J Pediatr Orthop B 15:449-452 (C) 2006 Lippincott Williams & Wilkins
Are Cemented Endoprosthetic Reconstructions Superior to Uncemented Endoprostheses in Terms of Postoperative Outcomes and Complications in Patients with Extremity-Located Bone Metastasis Scheduled for Adjuvant Radiotherapy?
No full textBackground: Adjuvant radiotherapy frequently is used for prevention of recurrence following resection and endoprosthetic reconstruction of bone metastases. Besides this positive effect, radiotherapy can negatively affect both cemented and uncemented endoprostheses. Methods: We retrospectively analyzed 130 extremities of 115 patients who underwent resection and cemented or uncemented endoprosthetic reconstruction for bone metastasis, followed by postoperative radiation therapy. The functional improvement was assessed by Karnofsky Performance Scale and Musculoskeletal Tumor Society (MSTS) scoring. The radiological evaluation mainly included analysis of “loosening areas” which were defined as the regions of osteolysis between the stem of the endoprostheses and the cement or cortex. The complications resulting in reconstruction failure and patient survival were recorded. Results: A survival analysis revealed that 21 (18.3%) patients were alive with disease and 94 (81.7%) died of disease at the time of study. The mean last follow-up Karnofsky Performance Scale and MSTS scores of the whole study cohort were 78.69 ± 8.66 and 82.15 ± 9.06, respectively. There were 8 (6.15%) complications resulting in reconstruction failure, including aseptic loosening (2), femoral stem breakage (2), periprosthetic fracture (2), and infection (2). The number and time of complications did not show a significant difference between the cemented and uncemented groups (P >.05). Conclusion: This study demonstrated that there was no significant difference in complication rates of cemented or uncemented endoprosthetic reconstructions in patients with extremity-located bone metastases scheduled for adjuvant radiotherapy. The only result in favor of cemented prostheses was significantly higher MSTS functional scores at last follow-up. © 2020 Elsevier Inc
Malign kitle rezeksiyonu takiben pediküllü latissimus dorsi flebi ile yumuşak doku rekonstrüksiyon uyguladığımız hastalarımızın retrospektif değerlendirilmesi
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