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Modified Continuous Loop Technique for microvascular anastomosis  [cached]
Kumar Pramod,Bhaskara K,Thomas P
Indian Journal of Plastic Surgery , 2001,
Abstract: A modified method of continuous loop technique for microvascular anastomosis is described. The handling of loop is easier & even last suture is placed under vision. This makes the microvascular anastomosis easier and simpler.
APC and chromosome instability in colorectal cancer APC e inestabilidad cromosómica en el cáncer de colon  [cached]
C. M. Cabrera,M. A. López-Nevot
Revista Espa?ola de Enfermedades Digestivas , 2005,
Abstract: Colon cancer is a common disease that can be sporadic or familial. An inactivated adenomatous polyposis coli (APC) suppressor gene is found in over 80% of colorectal tumors, this being an early alteration in the development of adenomatous polyps. APC function is not only critical for tumor initiation and progression, and chromosome instability (CIN) is another characteristic dependent at least partly on APC mutations. El cáncer de colon es una enfermedad frecuente que puede ser esporádica o familiar. La inactivación del gen supresor de tumores APC (adenomatous polyposis coli) se ha encontrado en más del 80% de los casos descritos de tumores colorrectales, apareciendo como una alteración temprana durante el desarrollo del pólipo adenomatoso. La inactivación del gen APC no es únicamente crítica en el proceso de iniciación y desarrollo del tumor, sino que igualmente la inestabilidad cromosómica (CIN) es otra característica dependiente al menos en parte de la presencia de mutaciones en APC.
The APC/C Ubiquitin Ligase: From Cell Biology to Tumorigenesis  [PDF]
Nagi George Ayad
Frontiers in Oncology , 2012, DOI: 10.3389/fonc.2011.00060
Abstract: The ubiquitin proteasome system (UPS) is required for normal cell proliferation, vertebrate development, and cancer cell transformation. The UPS consists of multiple proteins that work in concert to target a protein for degradation via the 26S proteasome. Chains of an 8.5-kDa protein called ubiquitin are attached to substrates, thus allowing recognition by the 26S proteasome. Enzymes called ubiquitin ligases or E3s mediate specific attachment to substrates. Although there are over 600 different ubiquitin ligases, the Skp1–Cullin–F-box (SCF) complexes and the anaphase promoting complex/cyclosome (APC/C) are the most studied. SCF involvement in cancer has been known for some time while APC/C’s cancer role has recently emerged. In this review we will discuss the importance of APC/C to normal cell proliferation and development, underscoring its possible contribution to transformation. We will also examine the hypothesis that modulating a specific interaction of the APC/C may be therapeutically attractive in specific cancer subtypes. Finally, given that the APC/C pathway is relatively new as a cancer target, therapeutic interventions affecting APC/C activity may be beneficial in cancers that are resistant to classical chemotherapy.
A Minimal Anaphase Promoting Complex/Cyclosome (APC/C) in Trypanosoma brucei  [PDF]
Mohamed Bessat, Giselle Knudsen, Alma L. Burlingame, Ching C. Wang
PLOS ONE , 2013, DOI: 10.1371/journal.pone.0059258
Abstract: The anaphase-promoting complex/cyclosome (APC/C) is a multi-subunit E3 ubiquitin ligase that initiates chromosome segregation and mitotic exit by targeting critical cell-cycle regulators for proteolytic destruction. Previously, seven APC/C subunit homologues were identified in the genome of Trypanosoma brucei. In the present study, we tested five of them in yeast complementation studies and found none of them capable of complementing the yeast mutants lacking the corresponding subunits, suggesting significant discrepancies between the two APC/C’s. Subunit homologues of mitotic checkpoint complex (MCC) have not yet been identified in T. brucei, raising the possibility that a MCC-APC/C complex equivalent may not exist in T. brucei. We performed tandem affinity purification of the protein complex containing a APC1 fusion protein expressed in the cells enriched in different phases of the cell cycle of procyclic form T. brucei, and compared their protein profiles using LC-MS/MS analyses. The seven putative APC/C subunits were identified in the protein complex throughout the cell cycle together with three additional proteins designated the associated proteins (AP) AP1, AP2 and AP3. Abundance of the 10 proteins remained relatively unchanged throughout the cell cycle, suggesting that they are the core subunits of APC/C. AP1 turned out to be a homologue of APC4. An RNAi knockdown of APC4 and AP3 showed no detectable cellular phenotype, whereas an AP2 knockdown enriched the cells in G2/M phase. The AP2-depleted cells showed stabilized mitotic cyclin B. An accumulation of poly-ubiquitinated cyclin B was indicated in the cells treated with the proteasome inhibitor MG132, demonstrating the involvement of proteasome in degrading poly-ubiquitinated cyclin B. In all, a 10-subunit APC/C machinery with a conserved function is identified in T. brucei without linking to a MCC-like complex, thus indicating a unique T. brucei APC/C.
lemmingA encodes the Apc11 subunit of the APC/C in Drosophila melanogaster that forms a ternary complex with the E2-C type ubiquitin conjugating enzyme, Vihar and Morula/Apc2
Olga Nagy, Margit Pál, Andor Udvardy, Christine AM Shirras, Imre Boros, Alan D Shirras, Péter Deák
Cell Division , 2012, DOI: 10.1186/1747-1028-7-9
Abstract: The lmg gene was initially identified through a pharate adult lethal P element insertion mutation expressing developmental abnormalities and widespread apoptosis in larval imaginal discs and pupal abdominal histoblasts. Larval neuroblasts were observed to arrest mitosis in a metaphase-like state with highly condensed, scattered chromosomes and frequent polyploidy. These neuroblasts contain high levels of both cyclin A and cyclin B. The lmg gene was cloned by virtue of the lmg03424 P element insertion which is located in the 5' untranslated region. The lemming locus is transcribed to give a 2.0 kb mRNA that contains two ORFs, lmgA and lmgB. The lmgA ORF codes for a putative protein with more than 80% sequence homology to the APC11 subunit of the human APC/C. The 85 amino acid protein also contains a RING-finger motif characteristic of known APC11 subunits. The lmgA ORF alone was sufficient to rescue the lethal and mitotic phenotypes of the lmg138 null allele and to complement the temperature sensitive lethal phenotype of the APC11-myc9 budding yeast mutant. The LmgA protein interacts with Mr/Apc2, and they together form a binding site for Vihar, the E2-C type ubiquitin conjugating enzyme. Despite being conserved among Drosophila species, the LmgB protein is not required for viability or fertility.Our work provides insight into the subunit structure of the Drosophila APC/C with implications for its function. Based on the presented data, we suggest that the Lmg/Apc11 subunit recruits the E2-C type ubiquitin conjugating enzyme, Vihar, to the APC/C together with Mr/Apc2 by forming a ternary complex.Chromosome separation at anaphase onset and exit from mitosis are regulated by ubiquitylation and subsequent degradation of key regulatory proteins, the securins and mitotic cyclins [1]. The ubiquitylation of these proteins is catalyzed by a cascade of E1, E2 and E3 enzymes, the crucial factor being the cell cycle regulated E3 ubiquitin protein ligase, the anaphase-promoting c
Thrombotic Microangiopathy Induced by Hyperthermal Intraperitoneal Chemotherapy with Mitomycin C  [PDF]
Mahir K?ksal, Robert J van Ginkel, Jan G Zijlstra
Surgical Science (SS) , 2011, DOI: 10.4236/ss.2011.24037
Abstract: A patient with pseudomyxoma peritonei underwent Hyperthermal Intraperitoneal Chemotherapy (HIPEC) with Mitomycin C after which she developed thrombotic microangiopathy. This syndrome mimicked possi-ble surgical complications. Treatment with plasma exchange resolved the syndrome and the patient recov-ered completely. This is the first description of thrombotic microangiopathy early after a single dose intrap-eritoneal Mitomycin C.
Running on a treadmill: dynamic inhibition of APC/C by the spindle checkpoint
Laura A Díaz-Martínez, Hongtao Yu
Cell Division , 2007, DOI: 10.1186/1747-1028-2-23
Abstract: Accurate chromosome segregation is the key event of mitosis. Errors in this process result in aneuploidy and genome instability, which contributes to cancer progression [1-4]. Mitotic chromosomes consist of pairs of sister chromatids that separate at the onset of anaphase. Sister-chromatid cohesion keeps sister chromatids together from the very moment of chromosome duplication until their separation. At metaphase, sister kinetochores are attached to microtubules emanating from opposite poles, a process referred to as amphitelic attachment or bi-orientation. A multisubunit ubiquitin ligase called the anaphase-promoting complex or cyclosome (APC/C) in conjunction with its mitotic activator Cdc20 then mediates the degradation of cyclin B and securin, allowing the activation of separase, cleavage of cohesin, and equal partition of sister chromatids into the two daughter cells [5,6]. Because microtubule attachment to kinetochores occurs stochastically, improper kinetochore-microtubule attachments, such as syntelic (sister kinetochores attach to microtubules from the same pole), monotelic (only one sister kinetochore attached), and merotelic attachments (a kinetochore attaches to microtubules from both poles), can form during mitosis [7,8]. These improper attachments ought to be corrected prior to sister-chromatid separation. Cells use a control mechanism termed the spindle checkpoint to ensure that all chromosomes are properly attached before initiating chromosome segregation [9,10].The spindle checkpoint monitors kinetochore-microtubule attachment and possibly inter-kinetochore tension generated by amphitelic attachments [11,12]. The unattached kinetochores are thought to produce diffusible checkpoint signals that inhibit APC/CCdc20 and block sister-chromatid separation [13,14]. An important checkpoint inhibitor of APC/C is the mitotic checkpoint complex that contains Mad2, Cdc20, Bub3 and BubR1 (Mad3 in budding yeast) [15], although it is presently unclear whether MCC
Role of C-Peptide in the Regulation of Microvascular Blood Flow  [PDF]
T. Forst,T. Kunt,B. Wilhelm,M. M. Weber,A. Pfützner
Experimental Diabetes Research , 2008, DOI: 10.1155/2008/176245
Abstract: During the recent years, the role of C-peptide, released from the pancreatic beta cell, in regulating microvascular blood flow, has received increasing attention. In type 1 diabetic patients, intravenous application of C-peptide in physiological concentrations was shown to increase microvascular blood flow, and to improve microvascular endothelial function and the endothelial release of NO. C-peptide was shown to impact microvascular blood flow by several interactive pathways, like stimulating Na
Effects of C-peptide on Microvascular Blood Flow and Blood Hemorheology  [PDF]
T. Forst,T. Kunt
Experimental Diabetes Research , 2004, DOI: 10.1080/15438600490424532
Abstract: Beside functional and structural changes in vascular biology, alterations in the rheologic properties of blood cells mainly determines to an impaired microvascular blood flow in patients suffering from diabetes mellitus. Recent investigations provide increasing evidence that impaired C-peptide secretion in type 1 diabetic patients might contribute to the development of microvascular complications. C-peptide has been shown to stimulate endothelial NO secretion by activation of the Ca2
APC/C-Cdh1-dependent anaphase and telophase progression during mitotic slippage
Kazuhiro Toda, Kayoko Naito, Satoru Mase, Masaru Ueno, Masahiro Uritani, Ayumu Yamamoto, Takashi Ushimaru
Cell Division , 2012, DOI: 10.1186/1747-1028-7-4
Abstract: Here we describe mitotic slippage in yeast bub2Δ mutant cells that are defective in the repression of precocious telophase onset (mitotic exit). Precocious activation of anaphase promoting complex/cyclosome (APC/C)-Cdh1 caused mitotic slippage in the presence of nocodazole, while the SAC was still active. APC/C-Cdh1, but not APC/C-Cdc20, triggered anaphase progression (securin degradation, separase-mediated cohesin cleavage, sister-chromatid separation and chromosome missegregation), in addition to telophase onset (mitotic exit), during mitotic slippage. This demonstrates that an inhibitory system not only of APC/C-Cdc20 but also of APC/C-Cdh1 is critical for accurate chromosome segregation in the presence of insufficient kinetochore-microtubule attachments.The sequential activation of APC/C-Cdc20 to APC/C-Cdh1 during mitosis is central to accurate mitosis. Precocious activation of APC/C-Cdh1 in metaphase (pre-anaphase) causes mitotic slippage in SAC-activated cells. For the prevention of mitotic slippage, concomitant inhibition of APC/C-Cdh1 may be effective for tumor therapy with mitotic spindle poisons in humans.The anaphase-promoting complex/cyclosome (APC/C) is an E3 ubiquitin ligase that plays a major role in cell cycle control by targeting substrates for proteasomal degradation. The complex is activated by two WD40 activator proteins, Cdc20/Fizzy/Fzy or Cdh1/Fizzy-related/Fzr. This destruction is strictly ordered to ensure that cell cycle events are executed in a timely fashion [1-5]. Whereas APC/C-Cdc20 is activated at metaphase-anaphase transition, APC/C-Cdh1 is activated after APC/C-Cdc20 activation. In the budding yeast Saccharomyces cerevisiae, APC/C-Cdh1 is activated from telophase to late G1 phase [6,7]. The switch from APC/C-Cdc20 to APC/C-Cdh1 is regulated by multiple mechanisms [5,8-10]: Cyclin B-Cdk1 (cyclin-dependent kinase) inhibits Cdh1 activation in metaphase, but cyclin B degradation mediated by APC/C in late M phase reduces cyclin B-Cdk1 acti
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