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1.
Sci Rep ; 14(1): 5595, 2024 Mar 07.
Artigo em Inglês | MEDLINE | ID: mdl-38454075

RESUMO

The interaction of localized light with matter generates optical electrostriction within dielectric fluids, leading to a discernible change in the refractive index of the medium according to the excitation's light profile. This optical force holds critical significance in optical manipulation and plays a fundamental role in numerous photonic applications. In this study, we demonstrate the applicability of the pump-probe, photo-induced lensing (PIL) method to investigate optical electrostriction in various dielectric liquids. Notably, the thermal and nonlinear effects are observed to be temporally decoupled from the electrostriction effects, facilitating isolated observation of the latter. Our findings provide a comprehensive explanation of optical forces in the context of the recently introduced microscopic Ampère electromagnetic formalism, which is grounded in the dipolar approximation of electromagnetic sources within matter and characterizes electrostriction as an electromagnetic-induced stress within the medium. Here, the optical force density is re-obtained through a new Lagrangian approach.

2.
Arch Orthop Trauma Surg ; 144(4): 1637-1645, 2024 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-38351348

RESUMO

INTRODUCTION: The frequency of proximal humeral fractures shows an increasing tendency, especially in the elderly, who are frequently affected by osteoporosis. The adequate treatment of complex, displaced fractures poses a serious challenge. Among surgical treatment options, osteosynthesis with an angular stable plate is preferred, however, the implant-related complication rate may be exceptionally high. In our present study, we report the short-term outcomes of our new method of valgising angular stable plate fixation which we use for multifragmentary, displaced proximal humeral fractures in elderly patients. MATERIALS AND METHODS: We retrospectively evaluated the clinical and radiological outcomes of 52 patients (46 female and 6 male, age: 71.9 ± 9.6) who suffered dislocated three- or four-part fractures and underwent valgising angular stable plate fixation. RESULTS: Mean follow-up time was 17.3 months, while the functional outcomes were as following: excellent in 26, good in 18, moderate in 5 and poor in 3 patients. The mean Constant-Murley Score was 82.5 ± 11.2. Functional outcomes only showed significant correlation (p = 0.031) with age and were proven unrelated to fracture type, BMI and known primary diseases. The cumulative complication rate was 9.6% and revision rate was 5.8%. Neurological deficit, pseudoarthrosis or avascular humeral head necrosis did not occur during the follow-up period. CONCLUSIONS: Valgising angular stable plate fixation that we apply for proximal humeral fractures provided favourable functional outcomes and a low postoperative complication rate due to the optimal head and plate placement. The method is especially effective for the treatment of displaced three- and four-part fractures with weakened, osteoporotic bone structure.


Assuntos
Fraturas do Úmero , Fraturas do Ombro , Humanos , Masculino , Feminino , Idoso , Pessoa de Meia-Idade , Idoso de 80 Anos ou mais , Resultado do Tratamento , Estudos Retrospectivos , Placas Ósseas , Fixação Interna de Fraturas/efeitos adversos , Fixação Interna de Fraturas/métodos , Fraturas do Ombro/cirurgia , Complicações Pós-Operatórias/epidemiologia , Complicações Pós-Operatórias/etiologia , Fraturas do Úmero/complicações
3.
Appl Opt ; 62(19): 5094-5098, 2023 Jul 01.
Artigo em Inglês | MEDLINE | ID: mdl-37707211

RESUMO

Piezo-optic and thermo-optic coefficients are important material properties that play a critical role in the design and optimization of many optical devices. The ability to accurately measure and control these coefficients is essential for achieving high performance and reliability in a wide range of applications. In this article, we use the optical detection of the ultrasound-induced thermal lens effect to investigate these properties for water at low temperatures. The results show that the anomalous behavior of water around 4°C is easily observed. The thermal lens method is used to determine the temperature dependence of the piezo-optic and thermo-optic coefficients.

4.
Rev Pneumol Clin ; 67(6): 375-9, 2011 Dec.
Artigo em Francês | MEDLINE | ID: mdl-22137284

RESUMO

The case concerns a 40 years old smoker male, treated for an adenocarcinoma of the left upper lobe, metastatic in muscle extended to the right femur cortex. The patient had first a surgical excision of the mass of the thigh, an intramedullary femoral nailing, and six courses of chemotherapy (cisplatin-vinorelbine) with concurrent thoracic radiotherapy. This treatment led to disease stability. One year later, hematuria revealed a bladder tumor. Cystoscopy with biopsy concluded to an adenocarcinoma pulmonary origin. The PET-scanner showed an uptake of the bladder mass, a hypermetabolic right adrenal gland and subcutaneous left shoulder nodule. The patient had a partial cystectomy associated with enterocystoplasty and left ureteral reimplantation, plus excision of the subcutaneous nodule located in the left shoulder and a right adrenalectomy during the same time. All of the sites were metastasis from adenocarcinoma of pulmonary origin. A salvage chemotherapy was initiated. In the vast majority of cases, bladder metastasis as primary bladder tumours is revealed by hematuria, cystitis or sometimes vague pelvic pain. Our case is a very unusual bladder metastatic site from lung cancer. We will discuss the different procedures and the therapeutic strategies on the basis of the published data.


Assuntos
Adenocarcinoma/patologia , Neoplasias das Glândulas Suprarrenais/secundário , Neoplasias Pulmonares/patologia , Neoplasias da Bexiga Urinária/secundário , Adenocarcinoma/complicações , Adenocarcinoma/diagnóstico , Adenocarcinoma de Pulmão , Neoplasias das Glândulas Suprarrenais/complicações , Neoplasias das Glândulas Suprarrenais/diagnóstico , Adulto , Neoplasias Ósseas/complicações , Neoplasias Ósseas/diagnóstico , Neoplasias Ósseas/secundário , Progressão da Doença , Fêmur , Síndrome de Horner/complicações , Humanos , Neoplasias Pulmonares/complicações , Neoplasias Pulmonares/diagnóstico , Masculino , Neoplasias Musculares/complicações , Neoplasias Musculares/diagnóstico , Neoplasias Musculares/secundário , Neoplasias da Bexiga Urinária/complicações , Neoplasias da Bexiga Urinária/diagnóstico
5.
J Environ Manage ; 90(3): 1404-12, 2009 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-18922619

RESUMO

In this paper, we investigate whether people's knowledge of the past influences their preferences and values towards future landscape change. "Knowledge of the past" is one aspect of the information set held by individuals, and a well-established finding in economics is that changes in information can change preferences and values. The particular aspects of knowledge of the past we work with here are: (i) awareness of past landuse, as represented by woodland cover and (ii) awareness of differing and sometimes contradictory literary impressions of this past landscape. The case studies used here relate to prospective changes in woodland cover in two UK national parks, the Lake District and the Trossachs. We find that people who are made aware that the landscape has changed over time, or that perceptions of the landscape have changed over time, are more likely to favour changes to the current landscape (are less likely to favour the status quo). Knowledge of the past therefore seems to have an impact on preferences for future landscapes. We also investigate the impacts on preferences of how "special", how "wild" and how "worked in" people perceive the landscapes of these two national parks to be.


Assuntos
Agricultura , Conservação dos Recursos Naturais/tendências , Participação da Comunidade , Ecossistema , Monitoramento Ambiental , Conhecimento , Plantas , Escócia , Inquéritos e Questionários
6.
Artigo em Alemão | MEDLINE | ID: mdl-17514470

RESUMO

The use of operations, visits to doctors and early diagnostic tests for children are examples of different services selected from the whole spectrum of preventative and therapeutic health service provisions in childhood and adolescence. In the German Health Interview and Examination Survey for Children and Adolescents (KiGGS), which is representative for Germany, 17,641 children and adolescents aged 0-17 or their parents were questioned on subjects such as their use of medical services. The use made of individual early diagnostic tests for children remains above the 90 % limit until the U7 test and drops to 89.0 % at U8, falling to 86.4 % at U9. 81 % of children took part in all the early diagnostic tests provided until age 6 (U3 to U9). Another 16 % only took advantage of some parts of this service and 3 % of the children never went to one of these check-ups. As was to be expected, the annual rate of visits to paediatricians drops as children get older from 95.1 % for 0-2-year-olds to 25.4 % of the 14-17-year-olds, while the rate of visits to general practitioners rises from 11.8 % to 53.1 %. If one tracks the rate of visits to specialist doctors all the way across childhood and adolescence, different paths emerge: while children aged 3-6 most often visit the ear, nose and throat doctor, at primary school age they mainly see opticians, and 14-17-year-olds most often visit doctors of internal medicine, dermatologists and surgeons. 37.1 % of the 0-17-year-old children and adolescents had undergone an operation. In order of declining frequency, the operations named were adenoidectomy (15.2 %), tonsillectomy (5.9 %), herniotomy (3.6 %) and appendectomy (2.4 %). Circumcisions had been carried out on 10.9 % of the boys. The different way medical services are used in different subgroups may not only depend on medical factors but also on social factors, medical attitudes and the availability of services provided.


Assuntos
Assistência Ambulatorial/estatística & dados numéricos , Programas de Rastreamento/estatística & dados numéricos , Medicina/normas , Especialização , Procedimentos Cirúrgicos Operatórios/estatística & dados numéricos , Adolescente , Fatores Etários , Criança , Pré-Escolar , Diagnóstico Precoce , Emigração e Imigração/estatística & dados numéricos , Medicina de Família e Comunidade/estatística & dados numéricos , Feminino , Alemanha , Serviços de Saúde , Inquéritos Epidemiológicos , Humanos , Lactente , Masculino , Pediatria/estatística & dados numéricos , Fatores Sexuais , Meio Social , Fatores Socioeconômicos , Revisão da Utilização de Recursos de Saúde/estatística & dados numéricos
7.
Int J Immunopathol Pharmacol ; 19(1): 35-48, 2006.
Artigo em Inglês | MEDLINE | ID: mdl-16569344

RESUMO

Binding of thrombospondin-1 (TSP-1) to the CD36 receptor inhibits angiogenesis and induces apoptosis in endothelial cells (EC). Conversely, matrix-bound TSP-1 supports vessel formation. In this study we analyzed the shear stress-dependent expression of TSP-1 and CD36 in endothelial cells in vitro and in vivo to reveal its putative role in the blood flow-induced remodelling of vascular networks. Shear stress was applied to EC using a cone-and-plate apparatus and gene expression was analyzed by RT-PCR, Northern and Western blot. Angiogenesis in skeletal muscles of prazosin-fed (50 mg/l drinking water; 4 d) mice was assessed by measuring capillary-to-fiber (C/F) ratios. Protein expression in whole muscle homogenates (WMH) or BS-1 lectin-enriched EC fractions (ECF) was analyzed by Western blot. Shear stress downregulated TSP-1 and CD36 expression in vitro in a force- and time-dependent manner sustained for at least 72 h and reversible by restoration of no-flow conditions. In vivo, shear stress-driven increase of C/F in prazosin-fed mice was associated with reduced expression of TSP-1 and CD36 in ECF, while TSP-1 expression in WMH was increased. Down-regulation of endothelial TSP-1/CD36 by shear stress suggests a mechanism for inhibition of apoptosis in perfused vessels and pruning in the absence of flow. The increase of extra-endothelial (e.g. matrix-bound) TSP-1 could support a splitting type of vessel growth.


Assuntos
Antígenos CD36/biossíntese , Células Endoteliais/metabolismo , Células Endoteliais/fisiologia , Neovascularização Patológica/fisiopatologia , Estresse Mecânico , Trombospondina 1/biossíntese , Antagonistas Adrenérgicos alfa/farmacologia , Fosfatase Alcalina/metabolismo , Animais , Northern Blotting , Western Blotting , Células Cultivadas , Hemodinâmica/fisiologia , Humanos , Camundongos , Camundongos Endogâmicos C57BL , Neovascularização Patológica/metabolismo , Prazosina/farmacologia , RNA/biossíntese , RNA/isolamento & purificação , Reação em Cadeia da Polimerase Via Transcriptase Reversa , Transcrição Gênica
8.
Artigo em Alemão | MEDLINE | ID: mdl-16270187

RESUMO

More than 90% of adults have a family doctor. The more chronic diseases and the more subjective health problems the interviewees had, the more often they had been to see their family doctor. Senior citizens and people with lower social status or a higher BMI go to see their family doctors more frequently. People who say they consume a lot of alcohol consult a doctor less often than others. Privately insured people also go to see their family doctors less frequently. Almost two-thirds of the adult population in Germany have seen a doctor in the last 3 months, and 44% of people over 60 had an influenza vaccination this year. People are much more willing to have an influenza injection in eastern Germany than in the west. More than half of the people questioned over the age of 35 has had a general health check-up at least once in their lives. Men have health check-ups slightly more often than women do. Of the women, 80% have participated at least once in a cancer screening programme, and as many as 60% of women had a cancer scan during the last year. Men take up cancer screening offers less often than women do. Inpatients stay for an average of 2 weeks in hospital per year. Just under 30% of those questioned have had medical rehabilitation treatment.


Assuntos
Inquéritos Epidemiológicos , Hospitalização/estatística & dados numéricos , Médicos de Família/estatística & dados numéricos , Atenção Primária à Saúde/estatística & dados numéricos , Saúde Pública/estatística & dados numéricos , Adulto , Distribuição por Idade , Idoso , Idoso de 80 Anos ou mais , Feminino , Alemanha/epidemiologia , Nível de Saúde , Humanos , Pacientes Internados/estatística & dados numéricos , Entrevistas como Assunto , Pessoa de Meia-Idade , Avaliação de Resultados em Cuidados de Saúde/métodos , Distribuição por Sexo , Inquéritos e Questionários
9.
Artigo em Alemão | MEDLINE | ID: mdl-16270188

RESUMO

The magnitude and the development of the prevalence of overweight and obesity in Germany during the past 20 years are analysed in this contribution. Using body mass index (BMI) data of the National Examination Surveys (1984-1992), the German National Health Interview and Examination Survey 1998 as well as the Telephone Health Survey 2003, all representative of the adult non-institutionalised population, the occurrence of overweight and obesity is studied. To improve the comparability with measurement values, the Telephone Health Survey data which were based on self-reporting were adjusted. All data were weighted to improve the representativeness for the time of assessment. Although the proportion of persons with a BMI between 25 and 30 did not change essentially during the last 20 years, the proportion of obese individuals (BMI>or=30) increased considerably. At present, about 70% of men and 50% of women in Germany are overweight or obese. In conclusion, the prevalence of overweight and obesity in Germany continues to increase.


Assuntos
Índice de Massa Corporal , Inquéritos Epidemiológicos , Entrevistas como Assunto , Obesidade/epidemiologia , Avaliação de Resultados em Cuidados de Saúde/métodos , Medição de Risco/métodos , Adulto , Distribuição por Idade , Idoso , Idoso de 80 Anos ou mais , Feminino , Alemanha/epidemiologia , Indicadores Básicos de Saúde , Humanos , Estilo de Vida , Masculino , Pessoa de Meia-Idade , Sobrepeso , Prevalência , Fatores de Risco , Distribuição por Sexo , Inquéritos e Questionários
10.
Artigo em Alemão | MEDLINE | ID: mdl-15768302

RESUMO

An analysis of the possible influences on primary health care utilization is made. The theoretical framework is the health behavioural model of R. M. Andersen, dividing the influencing variables into the components predisposing characteristics, enabling resources, and need factors. The study was based on data from the German National Health Examination and Interview Survey of the adult population in 1998. The data were linked to regional structural data and aggregated account data. The total number of contacts, the number of contacts with general practitioners and internists, and the number of different specialists contacted in the last 12 months, as calculated from interview data, were used to indicate primary health care utilization. In addition to the expected strong influence of need factors such as morbidity and health-related quality of life, the predisposing characteristics such as region, urban/rural, age, and gender have a significant influence on the primary care utilization. With regard to the enabling factors, persons with a family doctor had more contacts overall, which contrasts with the family doctor's assumed gate-keeper function. From the results of the study, recommendations on possible regulatory measures are given, but also some restrictions for influencing the number of contacts are pointed out.


Assuntos
Assistência Ambulatorial/estatística & dados numéricos , Programas Nacionais de Saúde/estatística & dados numéricos , Atenção Primária à Saúde/estatística & dados numéricos , Adulto , Assistência Ambulatorial/economia , Controle de Custos/estatística & dados numéricos , Medicina de Família e Comunidade/estatística & dados numéricos , Feminino , Alemanha , Comportamentos Relacionados com a Saúde , Inquéritos Epidemiológicos , Humanos , Medicina Interna/estatística & dados numéricos , Masculino , Medicina/estatística & dados numéricos , Programas Nacionais de Saúde/economia , Atenção Primária à Saúde/economia , Encaminhamento e Consulta/estatística & dados numéricos , Especialização , Procedimentos Desnecessários/estatística & dados numéricos
11.
Arch Orthop Trauma Surg ; 124(6): 401-3, 2004 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-15138774

RESUMO

INTRODUCTION: To evaluate the clinical and radiographic results immediately after total knee arthroplasty, we compared the parapatellar and subvastus approach. MATERIALS AND METHODS: Fifty-two patients with osteoarthritis were randomly assigned to two groups. The measurement was based on clinical and radiographic features. RESULTS: There was a significant difference in passive range of motion. Patients in the subvastus approach group revealed a full knee extension and flexion of 90 degrees significantly earlier than those in the parapatellar group. However, on the day of discharge, both groups were comparable. Radiological assessment revealed analogous results in both groups. Correction of varus or valgus deformity was required in 48 patients. CONCLUSION: Regardless of the surgical approach, the anteroposterior tibial femoral angle improved significantly in both groups. Concerning pain, operation time, blood loss, blood substitution and complications, no major differences could be seen.


Assuntos
Artroplastia do Joelho/métodos , Prótese do Joelho , Osteoartrite do Joelho/cirurgia , Amplitude de Movimento Articular/fisiologia , Idoso , Artroplastia do Joelho/reabilitação , Feminino , Seguimentos , Humanos , Masculino , Pessoa de Meia-Idade , Osteoartrite do Joelho/diagnóstico , Osteoartrite do Joelho/reabilitação , Medição da Dor , Patela , Período Pós-Operatório , Cuidados Pré-Operatórios , Estudos Prospectivos , Falha de Prótese , Resultado do Tratamento
12.
Gesundheitswesen ; 64 Suppl 1: S43-7, 2002 Dec.
Artigo em Alemão | MEDLINE | ID: mdl-12870215

RESUMO

The German National Health Survey for Children and Adolescents aims at collecting representative data on the health status of the population in the 0 to 18 years age bracket. Examination of about 18.000 participants is planned. In this cross-sectional study relevant data concerning health services will be gathered. These include parameters of health care demands, health insurance, vaccination status and drug utilisation. The data collection will start in the first quarter of 2003 and will probably be terminated in the last quarter of 2005. The study design has been tested in a pilot study for one year and was adapted to the demands of this specific health survey. The instruments used for data collection are a self-administered questionnaire as well as a standardised, computer-based medical interview.


Assuntos
Serviços de Saúde do Adolescente/estatística & dados numéricos , Serviços de Saúde da Criança/estatística & dados numéricos , Indicadores Básicos de Saúde , Avaliação das Necessidades/estatística & dados numéricos , Adolescente , Criança , Pré-Escolar , Estudos Transversais , Uso de Medicamentos/estatística & dados numéricos , Feminino , Alemanha , Inquéritos Epidemiológicos , Humanos , Lactente , Masculino , Revisão da Utilização de Recursos de Saúde/estatística & dados numéricos , Vacinação/estatística & dados numéricos
13.
Mutat Res ; 483(1-2): 83-8, 2001 Nov 01.
Artigo em Inglês | MEDLINE | ID: mdl-11600136

RESUMO

P210BCR-ABL counteracted against the complementary effect of XPB on DNA repair when ultraviolet (UV)-sensitive 27-1 cells were treated with UV or cisplatin but not with hydrogen peroxide. Wortmannin, an inhibitor of PI3 kinase did not affect its anti-repair effect. Enhanced recruitment of p44 with TFIIH after cisplatin treatment is inhibited by the expression of P210BCR-ABL in a kinase activity-dependent manner. Although purified TFIIH from P210BCR-ABL expressor and non-expressor showed almost no difference in molar ratio of each component, the in vitro activity of TFIIH was decreased by 5-10% in repair assay but was increased by more than two-fold in transcription assay.


Assuntos
Proteínas de Fusão bcr-abl/genética , Proteínas de Fusão bcr-abl/metabolismo , Cromossomo Filadélfia , Fatores de Transcrição TFII , Fatores de Transcrição/genética , Fatores de Transcrição/metabolismo , Animais , Células CHO , Cisplatino/toxicidade , Cricetinae , DNA Helicases , Reparo do DNA , Proteínas de Ligação a DNA/genética , Proteínas de Ligação a DNA/metabolismo , Humanos , Leucemia Mielogênica Crônica BCR-ABL Positiva/genética , Leucemia Mielogênica Crônica BCR-ABL Positiva/metabolismo , Fator de Transcrição TFIIH , Transfecção
14.
Trends Genet ; 17(5): 279-86, 2001 May.
Artigo em Inglês | MEDLINE | ID: mdl-11335038

RESUMO

Trichothiodystrophy (TTD) is a rare genetic disorder characterized by a hair dysplasia and associated with numerous symptoms affecting mainly organs derived from the neuroectoderm. About half of TTD patients exhibit photosensitivity because their nucleotide-excision repair pathway (NER) does not remove UV-induced DNA lesions efficiently. However, they do not present the skin cancer susceptibility expected from such an NER disorder. Their deficiencies result from phenotype-specific mutations in either XPB or XPD. These genes encode the helicase subunits of TFIIH, a DNA repair factor that is also required for transcription of class II genes. Thus, time- and tissue-specific impairments of transcription might explain the developmental and neurological symptoms of TTD. In a third group of photosensitive patients, TTD-A, no mutation has been identified, although TFIIH amount is reduced.


Assuntos
Anormalidades Múltiplas/genética , DNA Helicases , Reparo do DNA/genética , Doenças do Cabelo/genética , Transtornos de Fotossensibilidade/genética , Fatores de Transcrição TFII , Proteínas de Ligação a DNA/genética , Humanos , Ictiose/genética , Síndromes Neurocutâneas/genética , Fenótipo , Proteínas/genética , Fator de Transcrição TFIIH , Fatores de Transcrição/genética , Transcrição Gênica/genética , Raios Ultravioleta , Proteína Grupo D do Xeroderma Pigmentoso
15.
Int J Cancer ; 95(3): 176-83, 2001 May 20.
Artigo em Inglês | MEDLINE | ID: mdl-11307151

RESUMO

Amplification of the MYCN gene is significantly associated with an unfavorable prognosis and rapid progression in human neuroblastoma tumors. One potential mechanism by which MYCN may cause these effects is by deregulating cell proliferation. Tissue culture experiments support a model in which MYC genes stimulate cell cycle progression by antagonizing the function of the cell cycle inhibitor p27(kip1). In culture, activation of MYC induces both sequestration of p27(kip1) by cyclin D complexes and its subsequent proteolytic degradation. We have tested whether this model applies to human neuroblastoma in a retrospective study of 100 primary tumor biopsy samples from neuroblastoma patients with a documented follow-up. Consistent with this hypothesis, MYCN-amplified tumors express high levels of both cyclin A and proliferating cell nuclear antigen, 2 marker proteins of cell proliferation. Further, expression levels of p27(kip1) are of prognostic significance in human neuroblastoma patients. Similar to tissue culture systems, p27(kip1) is sequestered by cyclin D complexes in a subset of human neuroblastoma samples. Surprisingly, however, expression levels of p27(kip1) are prognostic independent of MYCN amplification, and tumors that have an amplified MYCN gene do not express elevated levels of D-type cyclins or contain significantly lower levels of p27(kip1). Our data do not support a model in which regulation of p27(kip1) function is an important mechanism by which amplified MYCN deregulates cell proliferation in neuroblastoma.


Assuntos
Biomarcadores Tumorais/biossíntese , Proteínas de Ciclo Celular , Proteínas Associadas aos Microtúbulos/biossíntese , Neuroblastoma/diagnóstico , Proteínas Proto-Oncogênicas c-myc/genética , Proteínas Supressoras de Tumor , Criança , Pré-Escolar , Inibidor de Quinase Dependente de Ciclina p27 , Amplificação de Genes , Humanos , Lactente , Recém-Nascido , Estadiamento de Neoplasias , Neuroblastoma/genética , Neuroblastoma/metabolismo , Neuroblastoma/mortalidade , Prognóstico , Análise de Sobrevida
16.
Nat Genet ; 26(3): 307-13, 2000 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-11062469

RESUMO

The repair-deficient form of trichothiodystrophy (TTD) most often results from mutations in the genes XPB or XPD, encoding helicases of the transcription/repair factor TFIIH. The genetic defect in a third group, TTD-A, is unknown, but is also caused by dysfunctioning TFIIH. None of the TFIIH subunits carry a mutation and TFIIH from TTD-A cells is active in both transcription and repair. Instead, immunoblot and immunofluorescence analyses reveal a strong reduction in the TFIIH concentration. Thus, the phenotype of TTD-A appears to result from sublimiting amounts of TFIIH, probably due to a mutation in a gene determining the complex stability. The reduction of TFIIH mainly affects its repair function and hardly influences transcription.


Assuntos
Anormalidades Múltiplas/genética , Reparo do DNA , Doenças do Cabelo/genética , Dermatopatias/genética , Fatores de Transcrição TFII , Fatores de Transcrição/fisiologia , Transcrição Gênica , Linhagem Celular Transformada , Síndrome de Cockayne/genética , Cisteína Endopeptidases/metabolismo , Dano ao DNA , DNA Helicases/deficiência , DNA Helicases/genética , Enzimas Reparadoras do DNA , Proteínas de Ligação a DNA/química , Proteínas de Ligação a DNA/deficiência , Proteínas de Ligação a DNA/genética , Fibroblastos/metabolismo , Fibroblastos/patologia , Teste de Complementação Genética , Heterogeneidade Genética , Doenças do Cabelo/metabolismo , Doenças do Cabelo/patologia , Células HeLa , Humanos , Substâncias Macromoleculares , Complexos Multienzimáticos/metabolismo , Proteínas de Ligação a Poli-ADP-Ribose , Complexo de Endopeptidases do Proteassoma , Subunidades Proteicas , Proteínas/química , Proteínas/genética , Dermatopatias/metabolismo , Dermatopatias/patologia , Síndrome , Fator de Transcrição TFIIH , Fatores de Transcrição/química , Fatores de Transcrição/deficiência , Xeroderma Pigmentoso/genética , Xeroderma Pigmentoso/patologia , Proteína Grupo D do Xeroderma Pigmentoso
17.
J Biol Chem ; 275(43): 33260-6, 2000 Oct 27.
Artigo em Inglês | MEDLINE | ID: mdl-10924514

RESUMO

In order to unravel the mechanism that regulates transcription of protein-coding genes, we investigated the function of the p44 subunit of TFIIH, a basal transcription factor that is also involved in DNA repair. We have shown previously that mutations in the C terminus of the XPD helicase, another subunit of TFIIH, prevent its regulation by p44 (Coin, F., Bergmann, E., Tremeau-Bravard, A., and Egly, J. M. (1999) EMBO 18, 1357-1366). By using a site-directed mutagenesis approach within the p44 region from amino acids 66 to 200, we indicate how a decrease in the interaction between p44 and XPD results in a decrease of the XPD helicase activity and leads to a defect in the first steps of the transcription reaction, namely the first phosphodiester bond formation and promoter clearance. We thus provide some explanation for the transcriptional defect found in SSL1 mutated yeast (Wang, Z., Buratowski, S., Svejstrup, J. Q., Feaver, W. J., Wu, X., Kornberg, R. D., Donahue, T. F., and Friedberg, E. C. (1995) Mol. Cell. Biol. 15, 2288-2293). Moreover, this study shows how the activity of the the cyclin-dependent kinase-activating kinase associated with TFIIH complex in stimulating transcription is mediated in part by p44/XPD interaction.


Assuntos
Adenosina Trifosfatases/fisiologia , DNA Helicases/fisiologia , Fatores de Transcrição TFII , Fatores de Transcrição/fisiologia , Transcrição Gênica , Adenosina Trifosfatases/química , Sequência de Aminoácidos , Sequência Conservada , DNA Helicases/química , Dados de Sequência Molecular , Subunidades Proteicas , Proteínas de Saccharomyces cerevisiae , Relação Estrutura-Atividade , Fator de Transcrição TFIIH
18.
Virology ; 265(1): 153-63, 1999 Dec 05.
Artigo em Inglês | MEDLINE | ID: mdl-10603326

RESUMO

The proteolytic processing of the viral polyprotein is an essential step during the life cycle of hepatitis A virus (HAV), as it is in all positive-sense, single-stranded RNA viruses of animals. In HAV the 3C proteinase is the only proteolytic activity involved in the polyprotein processing. The specific recognition of the cleavage sites by the 3C proteinase depends on the amino acid sequence of the cleavage site. The structure of the complex of the HAV 3C proteinase and a dipeptide inhibitor has been determined by X-ray crystallography. The double-mutant of HAV 3C (C24S, F82A) was inhibited with the specific inhibitor iodoacetyl-valyl-phenylalanyl-amide. The resulting complex had an acetyl-Val-Phe-amide group covalently attached to the S(gamma) atom of the nucleophilic Cys 172 of the enzyme. Crystals of the complex of HAV 3C (C24S, F82A) acetyl-Val-Phe-amide were found to be monoclinic, space group P2(1), having 4 molecules in the asymmetric unit and diffracting to 1.9-A resolution. The final refined structure consists of 4 molecules of HAV 3C (C24S,F82A) acetyl-Val-Phe-amide, 1 molecule of DMSO, 1 molecule of glycerol, and 514 water molecules. There are considerable conformational differences among the four molecules in the asymmetric unit. The final R-factor is 20.4% for all observed reflections between 15.0- and 1.9-A resolution and the corresponding R(free) is 29.8%. The dipeptide inhibitor is bound to the S(1)(') and S(2)(') specificity subsites of the proteinase. The crystal structure reveals that the HAV 3C proteinase possesses a well-defined S(2)(') specificity pocket and suggests that the P(2)(') residue could be an important determinant for the selection of the primary cleavage site during the polyprotein processing in HAV.


Assuntos
Cisteína Endopeptidases/metabolismo , Hepatovirus/enzimologia , Poliproteínas/metabolismo , Inibidores de Proteases/química , Proteínas Virais/metabolismo , Proteases Virais 3C , Cristalografia por Raios X , Substâncias Macromoleculares , Modelos Moleculares , Conformação Proteica , Relação Estrutura-Atividade
19.
Virus Res ; 62(2): 159-68, 1999 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-10507325

RESUMO

Picornaviruses are a family of positive-strand RNA viruses the members of which include poliovirus, hepatitis A virus, rhinovirus, foot-and-mouth disease virus and encephalomyocarditis virus. The genetic information contained in the single-stranded, positive sense RNA genome is expressed as a single protein of around 2000 amino acids. This primary product of protein synthesis, designated the polyprotein, is subsequently cleaved into the mature viral proteins by proteinases present within it. The properties of the three defined proteolytic activities present in the picornaviruses are reviewed and the three-dimensional structures of the hepatitis A 3C proteinase and the leader proteinase of foot-and-mouth disease virus as well as a model of the structure of the HRV2 2A proteinase are compared with those of chymotrypsin, papain and streptomyces griseus A proteinase, respectively.


Assuntos
Cisteína Endopeptidases/química , Endopeptidases/química , Picornaviridae/enzimologia , Proteínas Virais , Proteases Virais 3C , Cisteína Endopeptidases/metabolismo , Endopeptidases/metabolismo , Estrutura Terciária de Proteína
20.
Proc Natl Acad Sci U S A ; 96(20): 10968-75, 1999 Sep 28.
Artigo em Inglês | MEDLINE | ID: mdl-10500110

RESUMO

The three-dimensional structures of the inactive protein precursors (zymogens) of the serine, cysteine, aspartic, and metalloprotease classes of proteolytic enzymes are known. Comparisons of these structures with those of the mature, active proteases reveal that, in general, the preformed, active conformations of the residues involved in catalysis are rendered sterically inaccessible to substrates by the residues of the zymogens' N-terminal extensions or prosegments. The prosegments interact in nonsubstrate-like fashions with the residues of the active sites in most of the cases. The gastric aspartic proteases have a well-characterized zymogen conversion pathway. Structures of human progastricsin, the inactive intermediate 2, and active human pepsin are known and have been used to define the conversion pathway. The structure of the zymogen precursor of plasmepsin II, the malarial aspartic protease, shows a new twist on the mode of inactivation used by the gastric zymogens. The prosegment of proplasmepsin disrupts the active conformation of the two catalytic aspartic acid residues by inducing a major reorientation of the two domains of the mature protease. The picornaviral 2A and 3C proteases have a chymotrypsin-like tertiary structure but with a cysteine nucleophile. These enzymes cleave themselves from the viral polyprotein in cis (intramolecular cleavage) and carry out trans cleavages of other scissile peptides important for the virus life cycle. Although the structure of the precursor viral polyprotein is unknown, it probably resembles the organization of the proenzymes of the bacterial serine proteases, subtilisin, and alpha-lytic protease. Cleavage of the prosegment is known to occur in cis for these precursor molecules.


Assuntos
Ácido Aspártico Endopeptidases/química , Cisteína Endopeptidases/química , Precursores Enzimáticos/química , Pepsina A/química , Pepsinogênio C/química , Proteínas Virais , Proteases Virais 3C , Animais , Ácido Aspártico Endopeptidases/metabolismo , Catálise , Cisteína Endopeptidases/metabolismo , Ativação Enzimática , Precursores Enzimáticos/metabolismo , Humanos , Pepsina A/metabolismo , Pepsinogênio C/metabolismo , Proteínas de Protozoários
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