141 resultados para NUCLEOTIDE EXCISION-REPAIR


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Juvenile nasopharyngeal angiofibroma (JNA) is a rare vascular neoplasm occurring almost exclusively in adolescent males. Although benign, it is often locally aggressive and can erode into surrounding tissues and structures resulting in significant morbidity and mortality. In 20% of cases, there is intracranial extension. In this paper, we report on the total excision of a large, recurrent JNA with intracranial extension into the middle cranial fossa encroaching into the cavernous sinus, by right temporal craniotomy and extended osteoplastic maxillotomy.

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Hernia repair one of the most frequently performed operations in general surgery. With the introduction of tension-free mesh repair, recurrence rates dropped well below 5% for open and laparoscopic procedures. However, chronic postoperative pain remains a widely neglected complication with a high socio-economic impact. It occurs in about 10-20% of patients after hernia repair. We review the different types of post-herniorrhaphy pain with the typical diagnostic features and we conclude with a pragmatic algorithm based on our clinical experience.

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BACKGROUND: Single-center reports have identified retrograde ascending aortic dissection (rAAD) as a potentially lethal complication of thoracic endovascular aortic repair (TEVAR). METHODS AND RESULTS: Between 1995 and 2008, 28 centers participating in the European Registry on Endovascular Aortic Repair Complications reported a total of 63 rAAD cases (incidence, 1.33%; 95% CI, 0.75 to 2.40). Eighty-one percent of patients underwent TEVAR for acute (n=26, 54%) or chronic type B dissection (n=13, 27%). Stent grafts with proximal bare springs were used in majority of patients (83%). Only 7 (15%) patients had intraoperative rAAD, with the remaining occurring during the index hospitalization (n=10, 21%) and during follow-up (n=31, 64%). Presenting symptoms included acute chest pain (n=16, 33%), syncope (n=12, 25%), and sudden death (n=9, 19%) whereas one fourth of patients were asymptomatic (n=12, 25%). Most patients underwent emergency (n=25) or elective (n=5) surgical repair. Outcome was fatal in 20 of 48 patients (42%). Causes of rAAD included the stent graft itself (60%), manipulation of guide wires/sheaths (15%), and progression of underlying aortic disease (15%). CONCLUSIONS: The incidence of rAAD was low (1.33%) in the present analysis with high mortality (42%). Patients undergoing TEVAR for type B dissection appeared to be most prone for the occurrence of rAAD. This complication occurred not only during the index hospitalization but after discharge up to 1050 days after TEVAR. Importantly, the majority of rAAD cases were associated with the use of proximal bare spring stent grafts with direct evidence of stent graft-induced injury at surgery or necropsy in half of the patients.

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Patients with Ebstein's anomaly can present after childhood or adolescence with cyanosis, arrhythmias, severe right ventricular dysfunction and frequently with left ventricular dysfunction secondary to the prolonged cyanosis and to the right ventricular interference. At this point conventional repair is accompanied by elevated mortality and morbidity and poor functional results. We report our experience with three patients (8, 16 and 35 years of age) with Ebstein's anomaly, very dilated right atrium, severe tricuspid valve regurgitation (4/4), bi-directional shunt through an atrial septal defect and reduced left ventricular function (mean ejection fraction = 58%, mean shortening fraction = 25%). All underwent one and a half ventricular repair consisting of closure of the atrial septal defect, tricuspid repair with reduction of the atrialised portion of the right ventricle and end-to-side anastomosis of the superior vena cava to the right pulmonary artery. All patients survived, with a mean follow-up of 33 months. In all there was complete regression of the cyanosis and of the signs of heart failure. Postoperative echocardiography showed reduced degree of tricuspid regurgitation (2/4) and improvement of the left ventricular function (mean ejection fraction = 77%, mean shortening fraction = 40%). In patients with Ebstein's anomaly referred late for surgery with severely compromised right ventricular function or even with reduced biventricular function, the presence of a relatively hypoplastic and/or malfunctioning right ventricular chamber inadequate to sustain the entire systemic venous return but capable of managing part of the systemic venous return, permits a one and a half ventricular repair with good functional results.

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The IncP alpha promiscuous plasmid (R18, R68, RK2, RP1 and RP4) comprises 60,099 bp of nucleotide sequence, encoding at least 74 genes. About 40 kb of the genome, designated the IncP core and including all essential replication and transfer functions, can be aligned with equivalent sequences in the IncP beta plasmid R751. The compiled IncP alpha sequence revealed several previously unidentified reading frames that are potential genes. IncP alpha plasmids carry genetic information very efficiently: the coding sequences of the genes are closely packed but rarely overlap, and occupy almost 86% of the genome's nucleotide sequence. All of the 74 genes should be expressed, although there is as yet experimental evidence for expression of only 60 of them. Six examples of tandem-in-frame initiation sites specifying two gene products each are known. Two overlapping gene arrangements occupy different reading frames of the same region. Intergenic regions include most of the 25 promoters; transcripts are usually polycistronic. Translation of most of the open reading frames seems to be initiated independently, each from its own ribosomal binding and initiation site, although, a few cases of coupled translation have been reported. The most frequently used initiation codon is AUG but translation for a few open reading frames begins at GUG or UUG. The most common stop-codon is UGA followed by UAA and then UAG. Regulatory circuits are complex and largely dependent on two components of the central control operon. KorA and KorB are transcriptional repressors controlling at least seven operons. KorA and KorB act synergistically in several cases by recognizing and binding to conserved nucleotide sequences. Twelve KorB binding sites were found around the IncP alpha sequence and these are conserved in R751 (IncP beta) with respect to both sequence and location. Replication of IncP alpha plasmids requires oriV and the plasmid-encoded initiator protein TrfA in combination with the host-encoded replication machinery. Conjugative plasmid transfer depends on two separate regions occupying about half of the genome. The primary segregational stability system designated Par/Mrs consists of a putative site-specific recombinase, a possible partitioning apparatus and a post-segregational lethality mechanism, all encoded in two divergent operons. Proteins related to the products of F sop and P1 par partitioning genes are separately encoded in the central control operon.

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PURPOSE: To assess the usefulness of combining hyperthermia with a DNA repair inhibitor (double-strand break bait [Dbait]) and its potential application to radiofrequency ablation (RFA) in a preclinical model of human colorectal cancer. MATERIALS AND METHODS: The local ethics committee of animal experimentation approved all investigations. First, the relevance was assessed by studying the survival of four human colorectal adenocarcinoma cell cultures after 1 hour of hyperthermia at 41°C or 43°C with or without Dbait. Human colon adenocarcinoma cells (HT-29) were grafted subcutaneously into nude mice (n = 111). When tumors reached approximately 500 mm(3), mice were treated with Dbait alone (n = 20), sublethal RFA (n = 21), three different Dbait schemes and sublethal RFA (n = 52), or a sham treatment (n = 18). RFA was performed to ablate the tumor center alone. To elucidate antitumor mechanisms, 39 mice were sacrificed for blinded pathologic analysis, including assessment of DNA damage, cell proliferation, and tumor necrosis. Others were monitored for tumor growth and survival. Analyses of variance and log-rank tests were used to evaluate differences. RESULTS: When associated with mild hyperthermia, Dbait induced cytotoxicity in all tested colon cancer cell lines. Sublethal RFA or Dbait treatment alone moderately improved survival (median, 40 days vs 28 days for control; P = .0005) but combination treatment significantly improved survival (median, 84 days vs 40 days for RFA alone, P = .0004), with approximately half of the animals showing complete tumor responses. Pathologic studies showed that the Dbait and RFA combination strongly enhances DNA damage and coagulation areas in tumors. CONCLUSION: Combining Dbait with RFA sensitizes the tumor periphery to mild hyperthermia and increases RFA antitumor efficacy.

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In vertebrates, the RAD51 protein is required for genetic recombination, DNA repair, and cellular proliferation. Five paralogs of RAD51, known as RAD51B, RAD51C, RAD51D, XRCC2, and XRCC3, have been identified and also shown to be required for recombination and genome stability. At the present time, however, very little is known about their biochemical properties or precise biological functions. As a first step toward understanding the roles of the RAD51 paralogs in recombination, the human RAD51C and XRCC3 proteins were overexpressed and purified from baculovirus-infected insect cells. The two proteins copurify as a complex, a property that reflects their endogenous association observed in HeLa cells. Purified RAD51C--XRCC3 complex binds single-stranded, but not duplex DNA, to form protein--DNA networks that have been visualized by electron microscopy.

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INTRODUCTION: to assess the outcome of endovascular aortic aneurysm repair (EVAR) using intravascular ultrasound (IVUS) without angiography. MATERIALS/METHODS: eighty consecutive patients (median age 69 years (range 25-90): male 72 (90%), female 8 (10%)) underwent endovascular aneurysm repair (AAA 68 (85%), TAA 12 (15%)) using either angiography in 31/80 patients (39%) or IVUS in 49/80 patients (61%) in accordance to the surgeons preference. RESULTS: hospital mortality was 2/80 (3%), 1/68 for AAA (2%), 1/12 for TAA (8%), 2/31 for angiography (7%), and 0/49 for IVUS (0.0%: NS). Median quantity of contrast medium was 190 ml (range: 20-350) for angiography versus 0 ml for IVUS (p<0.01). Median X-ray exposure time 24 min (range 9-65 min) versus 8 min (range 0-60 min) for IVUS (p<0.05). No coverage of renal or suprarenal artery orifices occurred in either group. Conversion to open surgery was necessary in 4/80 patients (5%), 1/31 for angiography (3%) and 3/49 patients for IVUS (6%: NS). Early endoleaks were observed in 13/80 patients (16%): 8/31 patients for angiography (26%) versus 5/49 for IVUS (10%: p<0.05): 5/13 endoleaks resolved spontaneously (39%) whereas 8/13 (61%) required additional procedures. CONCLUSIONS: IVUS is a reliable tool for EVAR. In most cases, perprocedural angiography is not necessary.

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OBJECTIVE: To compare transanal endoscopic microsurgery (TEMS) with conventional transanal excision (TAE) in terms of the quality of resection, local recurrence, and survival rates in patients with stage I rectal cancer. BACKGROUND: Although TEMS is often considered a superior surgical technique to TAE, it is poorly suited for excising tumors in the lower third of the rectum. Such tumors may confer a worse prognosis. METHODS: We retrospectively reviewed information on all patients with stage pT1 and pT2 rectal adenocarcinoma who underwent local excision from 1997 through mid-2006. We excluded patients with node-positive, metastatic, recurrent, previously irradiated, or snare-excised tumors. RESULTS: Our study included 42 TEMS and 129 TAE patients. We found no significant differences in patient characteristics, adjuvant therapy, tumor stage, or adverse histopathologic features. In the TAE group, 52 (40%) of tumors were <5 cm from the anal verge (AV); in the TEMS group, only 1 (2%) (P = 0.0001). Surgical margins were less often positive in the TEMS group (2%) than in the TAE group (16%) (P = 0.017). For patients with tumors > or =5 cm from the AV, the estimated 5-year disease-free survival (DFS) rate was similar between the TEMS group (84.1%) and the TAE group (76.1%) (P = 0.651). But within the TAE group, the estimated 5-year DFS rate was better for patients with tumors > or =5 cm from the AV (76.1%) vs. <5 cm from the AV (60.5%) (P = 0.029). In our multivariate analysis, the tumor distance from the anal verge, the resection margin status, the T stage, and the use of adjuvant therapy--but not the surgical technique (i.e., TEMS or TAE) itself--were independent predictors of local recurrence and DFS. CONCLUSIONS: The quality of resection is better with TEMS than with TAE. However, the apparently better oncologic outcomes with TEMS can be partly explained by case selection of lower-risk tumors of the upper rectum.

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BACKGROUND: HIV-infected individuals have an increased risk of myocardial infarction. Antiretroviral therapy (ART) is regarded as a major determinant of dyslipidemia in HIV-infected individuals. Previous genetic studies have been limited by the validity of the single-nucleotide polymorphisms (SNPs) interrogated and by cross-sectional design. Recent genome-wide association studies have reliably associated common SNPs to dyslipidemia in the general population. METHODS AND RESULTS: We validated the contribution of 42 SNPs (33 identified in genome-wide association studies and 9 previously reported SNPs not included in genome-wide association study chips) and of longitudinally measured key nongenetic variables (ART, underlying conditions, sex, age, ethnicity, and HIV disease parameters) to dyslipidemia in 745 HIV-infected study participants (n=34 565 lipid measurements; median follow-up, 7.6 years). The relative impact of SNPs and ART to lipid variation in the study population and their cumulative influence on sustained dyslipidemia at the level of the individual were calculated. SNPs were associated with lipid changes consistent with genome-wide association study estimates. SNPs explained up to 7.6% (non-high-density lipoprotein cholesterol), 6.2% (high-density lipoprotein cholesterol), and 6.8% (triglycerides) of lipid variation; ART explained 3.9% (non-high-density lipoprotein cholesterol), 1.5% (high-density lipoprotein cholesterol), and 6.2% (triglycerides). An individual with the most dyslipidemic antiretroviral and genetic background had an approximately 3- to 5-fold increased risk of sustained dyslipidemia compared with an individual with the least dyslipidemic therapy and genetic background. CONCLUSIONS: In the HIV-infected population treated with ART, the weight of the contribution of common SNPs and ART to dyslipidemia was similar. When selecting an ART regimen, genetic information should be considered in addition to the dyslipidemic effects of ART agents.

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A 25-year-old male asylum-seeker presented with chest pain, exertional dyspnea, and orthopnea 20 years after the surgical repair of a pentalogy of Fallot. An extracardiac mass compressing the right ventricle was subsequently detected and surgical decompression was performed to relieve the resulting right intraventricular hypertension. At operation, the mass proved to be a coagulase-negative, staphylococcal abscess. In addition, the removal of the mass unmasked a previously nonrecognized pulmonary outflow stenosis that required balloon dilatation and beta-blocker therapy. While infections are known to occur after sternotomy, the formation of an abscess in the anterior mediastinum several years after the intervention appears to be exceptional; this diagnosis came to mind only after the more common complications had been considered, e.g., pseudoaneurysm or pericardial hematoma. To our knowledge, this is the first report of an abscess in the anterior mediastinum that had probably formed over many years following a sternotomy, compressed the right ventricle and masked a pulmonary stenosis.

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Over the past decade, use of autologous bone marrow-derived mononuclear cells (BMCs) has proven to be safe in phase-I/II studies in patients with myocardial infarction (MI). Taken as a whole, results support a modest yet significant improvement in cardiac function in cell-treated patients. Skeletal myoblasts, adipose-derived stem cells, and bone marrow-derived mesenchymal stem cells (MSCs) have also been tested in clinical studies. MSCs expand rapidly in vitro and have a potential for multilineage differentiation. However, their regenerative capacity decreases with aging, limiting efficacy in old patients. Allogeneic MSCs offer several advantages over autologous BMCs; however, immune rejection of allogeneic cells remains a key issue. As human MSCs do not express the human leukocyte antigen (HLA) class II under normal conditions, and because they modulate T-cell-mediated responses, it has been proposed that allogeneic MSCs may escape immunosurveillance. However, recent data suggest that allogeneic MSCs may switch immune states in vivo to express HLA class II, present alloantigen and induce immune rejection. Allogeneic MSCs, unlike syngeneic ones, were eliminated from rat hearts by 5 weeks, with a loss of functional benefit. Allogeneic MSCs have also been tested in initial clinical studies in cardiology patients. Intravenous allogeneic MSC infusion has proven to be safe in a phase-I trial in patients with acute MI. Endoventricular allogeneic MSC injection has been associated with reduced adverse cardiac events in a phase-II trial in patients with chronic heart failure. The long-term safety and efficacy of allogeneic MSCs for cardiac repair remain to be established. Ongoing phase-II trials are addressing these issues.

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BACKGROUND: The increasing number of completely sequenced bacterial genomes allows comparing their architecture and genetic makeup. Such new information highlights the crucial role of lateral genetic exchanges in bacterial evolution and speciation. RESULTS: Here we analyzed the twelve sequenced genomes of Streptococcus pyogenes by a naïve approach that examines the preferential nucleotide usage along the chromosome, namely the usage of G versus C (GC-skew) and T versus A (TA-skew). The cumulative GC-skew plot presented an inverted V-shape composed of two symmetrical linear segments, where the minimum and maximum corresponded to the origin and terminus of DNA replication. In contrast, the cumulative TA-skew presented a V-shape, which segments were interrupted by several steep slopes regions (SSRs), indicative of a different nucleotide composition bias. Each S. pyogenes genome contained up to nine individual SSRs, encompassing all described strain-specific prophages. In addition, each genome contained a similar unique non-phage SSR, the core of which consisted of 31 highly homologous genes. This core includes the M-protein, other mga-related factors and other virulence genes, totaling ten intrinsic virulence genes. In addition to a high content in virulence-related genes and to a peculiar nucleotide bias, this SSR, which is 47 kb-long in a M1GAS strain, harbors direct repeats and a tRNA gene, suggesting a mobile element. Moreover, its complete absence in a M-protein negative group A Streptococcus natural isolate demonstrates that it could be spontaneously lost, but in vitro deletion experiments indicates that its excision occurred at very low rate. The stability of this SSR, combined to its presence in all sequenced S. pyogenes sequenced genome, suggests that it results from an ancient acquisition. CONCLUSION: Thus, this non-phagic SSR is compatible with a pathogenicity island, acquired before S. pyogenes speciation. Its potential excision might bear relevance for vaccine development, because vaccines targeting M-protein might select for M-protein-negative variants that still carry other virulence determinants.