Your browser doesn't support javascript.
loading
Mostrar: 20 | 50 | 100
Resultados 1 - 16 de 16
Filtrar
1.
Klin Padiatr ; 234(4): 228-235, 2022 Jul.
Artigo em Alemão | MEDLINE | ID: mdl-35189655

RESUMO

BACKGROUND: Pancreatic tumors in children and adolescents are rare entities that can stay asymptomatic for long periods. They often become apparent as incidental findings or due to clinical symptoms, like abdominal pain. Solid pseudopapillary neoplasms of the pancreas (SPN) are rare representatives of this group, being low-grade malignant processes and requiring radical surgical treatment. We present four cases of SPN with different diagnostic and therapeutic approaches. METHODS: A retrospective analysis of four cases of SPN treated between 2015 and 2020 was performed. RESULTS: Four female patients (11-17 years) were found to have SPN during diagnostic procedures. Three of them were located in the pancreatic head. Histological confirmation was obtained with endosonographic-, CT-guided and open biopsy, respectively. R0 resection was achieved by a pylorus preserving, partial duodenopancreatectomy according to Traverso-Longmire. In one patient the tumor was located in the pancreatic tail with tumor adherence to the splenic vessels. A CT guided biopsy confirmed an SPN. A distal pancreatectomy and splenectomy was performed. Follow-up (6 months - 6 years) revealed no evidence of tumor recurrence, metastasis, or pancreoprive diabetes. CONCLUSION: For the treatment plan preoperative histological confirmation of SPN is necessary. Based on the tailored diagnostic and operative concepts, treatment at a center with a specialized pediatric surgery, pediatric oncology, pediatric gastroenterology, pediatric radiology and pathology is mandatory.


Assuntos
Recidiva Local de Neoplasia , Neoplasias Pancreáticas , Adolescente , Criança , Feminino , Humanos , Recidiva Local de Neoplasia/patologia , Pâncreas/patologia , Pâncreas/cirurgia , Pancreatectomia/métodos , Neoplasias Pancreáticas/diagnóstico , Neoplasias Pancreáticas/patologia , Neoplasias Pancreáticas/cirurgia , Estudos Retrospectivos , Resultado do Tratamento
2.
Glob Chang Biol ; 22(12): 3859-3864, 2016 12.
Artigo em Inglês | MEDLINE | ID: mdl-27185416

RESUMO

More than 100 countries pledged to reduce agricultural greenhouse gas (GHG) emissions in the 2015 Paris Agreement of the United Nations Framework Convention on Climate Change. Yet technical information about how much mitigation is needed in the sector vs. how much is feasible remains poor. We identify a preliminary global target for reducing emissions from agriculture of ~1 GtCO2 e yr-1 by 2030 to limit warming in 2100 to 2 °C above pre-industrial levels. Yet plausible agricultural development pathways with mitigation cobenefits deliver only 21-40% of needed mitigation. The target indicates that more transformative technical and policy options will be needed, such as methane inhibitors and finance for new practices. A more comprehensive target for the 2 °C limit should be developed to include soil carbon and agriculture-related mitigation options. Excluding agricultural emissions from mitigation targets and plans will increase the cost of mitigation in other sectors or reduce the feasibility of meeting the 2 °C limit.


Assuntos
Agricultura , Mudança Climática , Gases/análise , Efeito Estufa/prevenção & controle , Carbono/análise , Efeito Estufa/legislação & jurisprudência , Cooperação Internacional , Metano/análise , Política Pública , Solo/química
5.
Eur J Anaesthesiol ; 32(12): 857-61, 2015 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-26351828

RESUMO

BACKGROUND: In contrast to preoperative fasting guidelines in paediatric anaesthesia, actual fasting times are often too long. OBJECTIVE: The objective of this study was to evaluate the effect of preoperative fasting on glucose concentration, ketone bodies and acid-base balance in children. DESIGN: A prospective, noninterventional, clinical observational study. SETTING: A single-centre trial, study period from June 2014 to November 2014. PATIENTS: One hundred children aged 0 to 36 months scheduled for elective paediatric surgery. MAIN OUTCOME MEASURES: Patient demographics, fasting times, haemodynamic data, glucose and ketone body concentrations, and acid-base parameters after induction of anaesthesia were documented using a standardised case report form. RESULTS: Mean fasting period was 7.8 ± 4.5 (3.5 to 20) h, and deviation from guideline (ΔGL) was 3.3 ± 3.2 (-2 to 14) h. Linear regression showed a significant correlation between fasting times and ketone bodies, anion gap, base excess, osmolality as well as bicarbonate (for each, P < 0.05), but not glucose or lactate. In children with ΔGL more than 2 h (54%), ketone bodies, osmolality and anion gap were significantly higher and base excess significantly lower than children with ΔGL less than 2 h (for each, P < 0.05). CONCLUSION: After prolonged preoperative fasting, children younger than 36 months can present with ketoacidosis and (low) normal blood glucose concentrations. Actual fasting times should be optimised according to existing guidelines. In small infants, deviations from fasting guidelines should be as short as possible and not longer than 2 h.


Assuntos
Equilíbrio Ácido-Base/fisiologia , Glicemia/metabolismo , Jejum/sangue , Corpos Cetônicos/sangue , Cetose/sangue , Cuidados Pré-Operatórios/métodos , Pré-Escolar , Procedimentos Cirúrgicos Eletivos/métodos , Feminino , Humanos , Lactente , Recém-Nascido , Cetose/diagnóstico , Masculino , Estudos Prospectivos
6.
Crit Care ; 16(2): R37, 2012 Dec 12.
Artigo em Inglês | MEDLINE | ID: mdl-22386062

RESUMO

INTRODUCTION: Recent experimental data suggest that continuous external negative-pressure ventilation (CENPV) results in better oxygenation and less lung injury than continuous positive-pressure ventilation (CPPV). The effects of CENPV on patients with acute respiratory distress syndrome (ARDS) remain unknown. METHODS: We compared 2 h CENPV in a tankrespirator ("iron lung") with 2 h CPPV. The six intubated patients developed ARDS after pulmonary thrombectomy (n = 1), aspiration (n = 3), sepsis (n = 1) or both (n = 1). We used a tidal volume of 6 ml/kg predicted body weight and matched lung volumes at end expiration. Haemodynamics were assessed using the pulse contour cardiac output (PiCCO) system, and pressure measurements were referenced to atmospheric pressure. RESULTS: CENPV resulted in better oxygenation compared to CPPV (median ratio of arterial oxygen pressure to fraction of inspired oxygen of 345 mmHg (minimum-maximum 183 to 438 mmHg) vs 256 mmHg (minimum-maximum 123 to 419 mmHg) (P < 0.05). Tank pressures were -32.5 cmH2O (minimum-maximum -30 to -43) at end inspiration and -15 cmH2O (minimum-maximum -15 to -19 cmH2O) at end expiration. NO Inspiratory transpulmonary pressures decreased (P = 0.04) and airway pressures were considerably lower at inspiration (-1.5 cmH2O (minimum-maximum -3 to 0 cmH2O) vs 34.5 cmH2O (minimum-maximum 30 to 47 cmH2O), P = 0.03) and expiration (4.5 cmH2O (minimum-maximum 2 to 5) vs 16 cmH2O (minimum-maximum 16 to 23), P =0.03). During CENPV, intraabdominal pressures decreased from 20.5 mmHg (12 to 30 mmHg) to 1 mmHg (minimum-maximum -7 to 5 mmHg) (P = 0.03). Arterial pressures decreased by approximately 10 mmHg and central venous pressures by 18 mmHg. Intrathoracic blood volume indices and cardiac indices increased at the initiation of CENPV by 15% and 20% (P < 0.05), respectively. Heart rate and extravascular lung water indices remained unchanged. CONCLUSIONS: CENPV with a tank respirator improved gas exchange in patients with ARDS at lower transpulmonary, airway and intraabdominal pressures and, at least initially improving haemodynamics. Our observations encourage the consideration of further studies on the physiological effects and the clinical effectiveness of CENPV in patients with ARDS.


Assuntos
Intubação Intratraqueal , Respiração Artificial/métodos , Síndrome do Desconforto Respiratório/fisiopatologia , Síndrome do Desconforto Respiratório/terapia , APACHE , Adulto , Feminino , Hemodinâmica/fisiologia , Humanos , Masculino , Respiração com Pressão Positiva/métodos , Troca Gasosa Pulmonar , Mecânica Respiratória/fisiologia , Estatísticas não Paramétricas , Volume de Ventilação Pulmonar , Resultado do Tratamento
7.
Curr Opin Environ Sustain ; 58: 101208, 2022 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-36320406

RESUMO

The ongoing COVID-19 pandemic has spotlighted the intricate connections between human and planetary health. Given that pesticide-centered crop protection degrades ecological resilience and (in-)directly harms human health, the adoption of ecologically sound, biodiversity-driven alternatives is imperative. In this Synthesis paper, we illuminate how ecological forces can be manipulated to bolster 'tritrophic defenses' against crop pests, pathogens, and weeds. Three distinct, yet mutually compatible approaches (habitat-mediated, breeding-dependent, and epigenetic tactics) can be deployed at different organizational levels, that is, from an individual seed to entire farming landscapes. Biodiversity can be harnessed for crop protection through ecological infrastructures, diversification tactics, and reconstituted soil health. Crop diversification is ideally guided by interorganismal interplay and plant-soil feedbacks, entailing resistant cultivars, rotation schemes, or multicrop arrangements. Rewarding opportunities also exist to prime plants for enhanced immunity or indirect defenses. As tritrophic defenses spawn multiple societal cobenefits, they could become core features of healthy, climate-resilient, and low-carbon food systems.

8.
Muscle Nerve ; 42(3): 305-10, 2010 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-20544943

RESUMO

Current methods of artificial ventilation cannot prevent diverse problems associated with mechanical ventilation. In contrast to all current forms of mechanical ventilation, electromagnetic stimulation can activate respiratory muscles directly. However, it is not known if and to what extent electromagnetic stimulation can ventilate humans. In 10 volunteers we stimulated the lateral neck using magnetic stimulators. Over 63 s we stimulated nine times with a frequency of 25 HZ for 1.1 s using 600 V, 900 V, and 1,200 V. The minimum stimulation time for each volunteer was 9 min. A Capnomac monitor measured minute ventilation. Electromagnetic stimulation was well tolerated and safe. Bilateral stimulation with 600 V achieved considerable minute ventilation (median +/- SD, 7.2 +/- 3.4 L/min) that increased at higher voltage levels (P < 0.0001). 900 V achieved sufficient minute ventilation in all volunteers (11.5 +/- 5.0 L/min; 1200 V, 14.0 +/- 4.9 L/min). This first evaluation of electromagnetic ventilation demonstrates that it can be used to ventilate humans sufficiently. This method may be developed to a new mode of ventilation.


Assuntos
Respiração Artificial/métodos , Ventiladores Mecânicos , Adulto , Índice de Massa Corporal , Estimulação Elétrica , Campos Eletromagnéticos , Feminino , Humanos , Músculos Intercostais , Modelos Lineares , Masculino , Pescoço/anatomia & histologia , Nervo Frênico/fisiologia , Músculos Respiratórios , Adulto Jovem
9.
Nucleic Acids Res ; 35(15): e95, 2007.
Artigo em Inglês | MEDLINE | ID: mdl-17652325

RESUMO

Direct UV cross-linking combined with mass spectrometry (MS) is a powerful tool to identify hitherto non-characterized protein-RNA contact sites in native ribonucleoprotein particles (RNPs) such as the spliceosome. Identification of contact sites after cross-linking is restricted by: (i) the relatively low cross-linking yield and (ii) the amount of starting material available for cross-linking studies. Therefore, the most critical step in such analyses is the extensive purification of the cross-linked peptide-RNA heteroconjugates from the excess of non-crosslinked material before MS analysis. Here, we describe a strategy that combines small-scale reversed-phase liquid chromatography (RP-HPLC) of UV-irradiated and hydrolyzed RNPs, immobilized metal-ion affinity chromatography (IMAC) to enrich cross-linked species and their analysis by matrix-assisted laser desorption/ionisation (MALDI) MS(/MS). In cases where no MS/MS analysis can be performed, treatment of the enriched fractions with alkaline phosphatase leads to unambiguous identification of the cross-linked species. We demonstrate the feasibility of this strategy by MS analysis of enriched peptide-RNA cross-links from UV-irradiated reconstituted [15.5K-61K-U4atac snRNA] snRNPs and native U1 snRNPs. Applying our approach to a partial complex of U2 snRNP allowed us to identify the contact site between the U2 snRNP-specific protein p14/SF3b14a and the branch-site interacting region (BSiR) of U2 snRNA.


Assuntos
Peptídeos/química , RNA Nuclear Pequeno/química , Ribonucleoproteínas Nucleares Pequenas/química , Espectrometria de Massas por Ionização e Dessorção a Laser Assistida por Matriz , Fosfatase Alcalina , Sequência de Aminoácidos , Sítios de Ligação , Cromatografia de Afinidade , Cromatografia Líquida/métodos , Biologia Computacional , Dados de Sequência Molecular , Peptídeos/isolamento & purificação , RNA Nuclear Pequeno/isolamento & purificação , Ribonucleoproteína Nuclear Pequena U1/química , Ribonucleoproteína Nuclear Pequena U1/efeitos da radiação , Ribonucleoproteína Nuclear Pequena U2/química , Ribonucleoproteína Nuclear Pequena U2/efeitos da radiação , Ribonucleoproteínas Nucleares Pequenas/efeitos da radiação , Raios Ultravioleta
10.
Parasit Vectors ; 10(1): 457, 2017 10 09.
Artigo em Inglês | MEDLINE | ID: mdl-28992814

RESUMO

BACKGROUND: Welfare concerns, production losses caused by Dermanyssus gallinae, the poultry red mite (PRM), and widespread mite resistance to environmentally applied acaricides continue to drive an urgent need for new and effective control measures. Fluralaner is a novel systemic acaricide developed to address that need. A series of field studies was initiated to investigate the safety and efficacy of a fluralaner solution (10 mg/ml) administered in drinking water at a dose rate of 0.5 mg/kg on two occasions with a 7-day interval, for treatment of natural PRM infestations in chickens. METHODS: Blinded, negative-controlled studies were completed in Europe across eight layer, two breeder, and two replacement chicken farms. At each farm, two similar flocks were housed in similar PRM-infested units (either rooms within a building, or separate buildings) varying from 550 to 100,000 birds per unit. One unit at each farm was allocated to fluralaner treatment, administered in drinking water on Days 0 and 7. One unit remained untreated. Mite traps were placed throughout each unit on Days -1, 0 or 1, 3, 6, 9, and 13 or 14, then at weekly or two-weekly intervals, retrieved after 24 h and processed for mite counts. Efficacy at each farm was assessed by mean PRM count reductions from traps in treated units compared with those from control units. Production parameters and safety were also monitored. RESULTS: Efficacy was 95.3 to 99.8% on Day 3 and 97.8 to 100% on Day 9, thereafter remaining above 90% for 56 to 238 days after treatment initiation. Post-treatment improvement in egg-laying rate was greater by 0.9 to 12.6% in the treated group at 9 of the 10 layer or breeder farms. There were no treatment-related adverse events. CONCLUSION: Fluralaner administered at 0.5 mg/kg via drinking water twice, 7 days apart, was well tolerated and highly efficacious against the PRM in naturally infested chickens representing a range of production types and management systems. The results indicate that this novel treatment has potential to be the cornerstone of an integrated approach to reducing or eliminating the welfare and productivity costs of this increasingly threatening pest.


Assuntos
Água Potável , Infestações por Ácaros , Ácaros/efeitos dos fármacos , Oncocercose , Doenças das Aves Domésticas , Animais , Galinhas , Europa (Continente) , Isoxazóis , Aves Domésticas
11.
Clin Cancer Res ; 11(12): 4382-7, 2005 Jun 15.
Artigo em Inglês | MEDLINE | ID: mdl-15958621

RESUMO

The management of Wilms' tumors consists of a combination of surgery, chemotherapy, and possibly radiotherapy. To date, chemotherapy is being risk stratified according to histologic subtype and stage. Although the cytogenetic characteristics of Wilms' tumors are well established, the cytogenetic effects related to chemotherapy are widely unknown. We herein report on comparative genomic hybridization findings in 41 primary Wilms' tumors of blastemal type, of which 19 had received preoperative chemotherapy (PCT group) and 22 did not (non-PCT group). Overall, imbalances could be detected in 32 tumors, with +1q (17 cases), +7q (10 cases), +7p (6 cases), and -7p (6 cases) as the most common changes. Among these, +7q and -7p were both significantly associated with metastatic disease at the time of surgery (P = 0.002 and 0.007, respectively), and +7q was also associated with higher stage (stages III + IV; P = 0.003). There were significant differences in the cytogenetic constitution of tumors between the two treatment groups. As a trend, tumors in the preoperative-chemotherapy group had fewer changes (mean, 2.7) than those in the non-preoperative-chemotherapy group (mean, 3.8), and the frequencies of imbalances at 7p or +7q, respectively, were significantly lower compared with tumors in the non-preoperative-chemotherapy group (2 of 19 versus 10 of 22, P = 0.019; 1 of 19 versus 9 of 22, P = 0.011). In contrast, -1q was common in both the preop-CT group (10 of 19) and the non-preop-CT group (7 of 22). The results suggest that Wilms' tumor clones with +1q are not obliterated by preoperative chemotherapy, whereas cytogenetically more complex clones with +7q and/or imbalances at 7p seem more responsive and are more likely to be eliminated by chemotherapeutic treatment.


Assuntos
Aberrações Cromossômicas/induzido quimicamente , Tumor de Wilms/tratamento farmacológico , Adolescente , Antineoplásicos/efeitos adversos , Antineoplásicos/uso terapêutico , Criança , Pré-Escolar , Cromossomos Humanos Par 1/efeitos dos fármacos , Cromossomos Humanos Par 1/genética , Cromossomos Humanos Par 7/efeitos dos fármacos , Cromossomos Humanos Par 7/genética , Feminino , Seguimentos , Humanos , Lactente , Masculino , Estadiamento de Neoplasias , Hibridização de Ácido Nucleico/métodos , Análise de Sobrevida , Tumor de Wilms/genética , Tumor de Wilms/patologia
12.
PLoS One ; 7(7): e40903, 2012.
Artigo em Inglês | MEDLINE | ID: mdl-22829896

RESUMO

BACKGROUND: A high incidence of epileptiform activity in the electroencephalogram (EEG) was reported in children undergoing mask induction of anaesthesia with administration of high doses of sevoflurane for 5 minutes and longer. This study was performed to investigate whether reducing the time of exposure to a high inhaled sevoflurane concentration would affect the incidence of epileptiform EEG activity. It was hypothesized that no epileptiform activity would occur, when the inhaled sevoflurane concentration would be reduced from 8% to 4% immediately after the loss of consciousness. METHODOLOGY/PRINCIPAL FINDINGS: 70 children (age 7-96 months, ASA I-II, premedication with midazolam) were anaesthetized with 8% sevoflurane in 100% oxygen via face mask. Immediately after loss of consciousness, the sevoflurane concentration was reduced to 4%. EEGs were recorded continuously and were later analyzed visually with regard to epileptiform EEG patterns. Sevoflurane at a concentration of 8% was given for 1.2 ± 0.4 min (mean ± SD). In 14 children (20%) epileptiform EEG patterns without motor manifestations were observed (delta with spikes (DSP), rhythmic polyspikes (PSR), epileptiform discharges (PED) in 10, 10, 4 children (14%, 14%, 6%)). 38 children (54%) had slow, rhythmic delta waves with high amplitudes (DS) appearing on average before DSP. CONCLUSIONS/SIGNIFICANCE: The hypothesis that no epileptiform potentials would occur during induction of anaesthesia with a reduction of the inspired sevoflurane concentration from 8% to 4% directly after LOC was not proved. Even if 8% sevoflurane is administered only briefly for induction of anaesthesia, epileptiform EEG activity may be observed in children despite premedication with midazolam.


Assuntos
Anestésicos Inalatórios/uso terapêutico , Eletroencefalografia , Éteres Metílicos/uso terapêutico , Anestésicos Inalatórios/administração & dosagem , Criança , Pré-Escolar , Feminino , Humanos , Incidência , Lactente , Masculino , Éteres Metílicos/administração & dosagem , Midazolam/farmacologia , Estudos Prospectivos , Sevoflurano
13.
Cancer Genet ; 204(3): 122-8, 2011 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-21504711

RESUMO

Pulmonary metastases (PM) are frequent in colorectal carcinoma (CRC). However, little is known about the chromosomal imbalances in CRC that accompany metastatic pulmonary disease. We investigated tumor specimens of CRC (n=30) and their corresponding PM by comparative genomic hybridization (CGH). There were no substantial differences in the degree of chromosomal instability between CRC and PM, neither in average number of copy alterations (ANCA; 6.6 ± 0.8 and 7.7 ± 0.9) nor in gains (2.6 ± 0.5 and 2.6 ± 0.4), losses (3.6 ± 0.5 and 4.8 ± 0.6), or amplifications (0.4 ± 0.1 and 0.3 ± 0.1). Basically, similar patterns of chromosomal imbalances could be identified in both CRC and corresponding PM, most frequently including chromosomal gains at 7, 8q, 13q, and 20q, as well as losses at 4, 8p, 18q, and 20p. CRC and corresponding PM differed in frequencies for losses at chromosome arm 5q (3 vs. 26%; P=0.012). Losses at 4q and 11q in CRC were significantly associated with lower 5-year survival rates (80 vs. 24%, P=0.026 and 74 vs. 17%, P=0.007, respectively), and they may represent candidates for adverse prognostic markers in primary CRC.


Assuntos
Aberrações Cromossômicas , Neoplasias Colorretais/genética , Neoplasias Colorretais/patologia , Neoplasias Pulmonares/genética , Neoplasias Pulmonares/secundário , Idoso , Mapeamento Cromossômico , Hibridização Genômica Comparativa/métodos , Feminino , Perfilação da Expressão Gênica , Humanos , Masculino , Pessoa de Meia-Idade
14.
Cancer Genet Cytogenet ; 198(1): 47-51, 2010 Apr 01.
Artigo em Inglês | MEDLINE | ID: mdl-20303014

RESUMO

Information on structural chromosomal changes in brain metastases (BM) of colorectal carcinoma (CRC) is very limited. Therapeutic and diagnostic strategies to reduce the risk of BM have potential impact on cancer mortality. By using comparative genomic hybridization, the primary CRC of 11 patients and their corresponding 13 BM were analyzed. BM showed significantly more mean chromosomal aberrations than the primary CRC (13.6+/-2.1 vs. 7.9+/-1.9, P=0.03), significantly more chromosomal gains (7.2+/-0.9 vs. 3.5+/-0.9, P=0.01), and tended to have also more losses (6.1+/-1.4 vs. 4.0+/-1.1, P=0.29). Changes that occurred significantly more often in BM than in primary CRC were gains of 8q, 12p, 12q, and 20p, as well as losses of 5q. BM of CRC show a significantly higher chromosomal instability in comparison to primary tumors. The prevalently altered genomic regions in the metastases of this study are likely to harbor genes that play an important role in the genesis of brain-specific metastasis.


Assuntos
Neoplasias Encefálicas/genética , Neoplasias Encefálicas/secundário , Carcinoma/genética , Carcinoma/secundário , Neoplasias Colorretais/patologia , Adulto , Idoso , Instabilidade Cromossômica , Aberrações Cromossômicas , Neoplasias Colorretais/genética , Hibridização Genômica Comparativa , Humanos , Masculino , Pessoa de Meia-Idade
15.
Science ; 323(5920): 1477-81, 2009 Mar 13.
Artigo em Inglês | MEDLINE | ID: mdl-19286556

RESUMO

Once all chromosomes are connected to the mitotic spindle (bioriented), anaphase is initiated by the protein ubiquitylation activity of the anaphase-promoting complex/cyclosome (APC/C) and its coactivator Cdc20 (APC/C(Cdc20)). Before chromosome biorientation, anaphase is delayed by a mitotic checkpoint complex (MCC) that inhibits APC/C(Cdc20). We used single-particle electron microscopy to obtain three-dimensional models of human APC/C in various functional states: bound to MCC, to Cdc20, or to neither (apo-APC/C). These experiments revealed that MCC associates with the Cdc20 binding site on APC/C, locks the otherwise flexible APC/C in a "closed" state, and prevents binding and ubiquitylation of a wide range of different APC/C substrates. These observations clarify the structural basis for the inhibition of APC/C by spindle checkpoint proteins.


Assuntos
Mitose , Fuso Acromático/metabolismo , Complexos Ubiquitina-Proteína Ligase/química , Complexos Ubiquitina-Proteína Ligase/metabolismo , Anáfase , Ciclossomo-Complexo Promotor de Anáfase , Proteínas Cdc20 , Proteínas de Ciclo Celular/química , Proteínas de Ciclo Celular/metabolismo , Células HeLa , Humanos , Processamento de Imagem Assistida por Computador , Imageamento Tridimensional , Microscopia Eletrônica , Modelos Moleculares , Ligação Proteica , Conformação Proteica , Estrutura Terciária de Proteína , Enzimas de Conjugação de Ubiquitina/química , Enzimas de Conjugação de Ubiquitina/metabolismo , Ubiquitinação
16.
RNA ; 11(12): 1915-30, 2005 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-16314460

RESUMO

Protein-RNA cross-linking combined with mass spectrometry is a powerful tool to elucidate hitherto non-characterized protein-RNA contacts in ribonucleoprotein particles, as, for example, within spliceosomes. Here, we describe an improved methodology for the sequence analysis of purified peptide-RNA oligonucleotide cross-links that is based solely on MALDI-ToF mass spectrometry. The utility of this methodology is demonstrated on cross-links isolated from UV-irradiated spliceosomal particles; these were (1) [15.5K-61 K-U4 atac] small nuclear ribonucleoprotein (snRNP) particles prepared by reconstitution in vitro, and (2) U1 snRNP particles purified from HeLa cells. We show that the use of 2',4',6'-trihydroxyacetophenone (THAP) as MALDI matrix allows analysis of cross-linked peptide-RNA oligonucleotides in the reflectron mode at high resolution, enabling sufficient accuracy to assign unambiguously cross-linked RNA sequences. Most important, post-source decay (PSD) analysis under these conditions was successfully applied to obtain sequence information about the cross-linked peptide and RNA moieties within a single spectrum, including the identification of the actual cross-linking site. Thus, in U4 atac snRNA we identified His 270 in the spliceosomal U4/U6 snRNP-specific protein 61 K (hPrp31p) cross-linked to U 44; in the U1 snRNP we show that Leu175 of the U1 snRNP-specific 70K protein is cross-linked to U 30 of U1 snRNA. This type of analysis is applicable to any type of RNP complex and may be expected to pave the way for the further analysis of protein-RNA complexes in much lower abundance and/or of cross-links that are obtained in low yield.


Assuntos
Reagentes de Ligações Cruzadas/farmacologia , Oligonucleotídeos/análise , Peptídeos , RNA/química , Espectrometria de Massas por Ionização e Dessorção a Laser Assistida por Matriz , Raios Ultravioleta , Sequência de Aminoácidos , Cristalografia por Raios X , Células HeLa , Humanos , Modelos Químicos , Modelos Moleculares , Dados de Sequência Molecular , Ribonucleoproteína Nuclear Pequena U1/química , Ribonucleoproteína Nuclear Pequena U1/metabolismo , Ribonucleoproteína Nuclear Pequena U4-U6/química , Ribonucleoproteína Nuclear Pequena U4-U6/metabolismo , Homologia de Sequência de Aminoácidos
SELEÇÃO DE REFERÊNCIAS
Detalhe da pesquisa