Your browser doesn't support javascript.
loading
Mostrar: 20 | 50 | 100
Resultados 1 - 20 de 29
Filtrar
Mais filtros










Base de dados
Intervalo de ano de publicação
1.
Nervenarzt ; 75(9): 888-95, 2004 Sep.
Artigo em Alemão | MEDLINE | ID: mdl-15378249

RESUMO

We report on the development of a German self-rating behaviour questionnaire (ADHD-SR) and diagnostic checklist (ADHD-DC) for the diagnosis of attention-deficit/hyperactivity disorder in adults according to DSM IV and ICD 10 research criteria. When comparing self-rating with expert rating, we found good concordance measured by intraclass coefficients on the level of single symptoms and syndrome scores. High retest reliability of the ADHD-SR demonstrated the ability to assess time-stable behaviour traits. Evaluation of the psychometric properties revealed good internal consistency and adequate convergent and divergent validity measured by the "big five" derived from the NEO-FFI and the constructs impulsivity, venturesomeness, and empathy of Eysenck's impulsiveness questionnaire. We detected a remarkable correlation with the Wender Utah Rating Scale, which targets the detection of childhood ADHD symptoms. Diagnostic sensitivity for different cutoff points was calculated by ROC analysis at 65--88%. Specificity was 67% to 92%.


Assuntos
Transtorno do Deficit de Atenção com Hiperatividade/diagnóstico , Testes Neuropsicológicos/estatística & dados numéricos , Determinação da Personalidade/estatística & dados numéricos , Inventário de Personalidade/estatística & dados numéricos , Adulto , Transtorno do Deficit de Atenção com Hiperatividade/psicologia , Manual Diagnóstico e Estatístico de Transtornos Mentais , Feminino , Humanos , Classificação Internacional de Doenças , Masculino , Pessoa de Meia-Idade , Psicometria/estatística & dados numéricos , Reprodutibilidade dos Testes , Estatística como Assunto , Inquéritos e Questionários
2.
Nervenarzt ; 74(11): 987-93, 2003 Nov.
Artigo em Alemão | MEDLINE | ID: mdl-14598035

RESUMO

The diagnosis of adult attention deficit/hyperactivity disorder (ADHD) requires the retrospective assessment of ADHD symptoms in childhood. The Wender Utah Rating Scale (WURS) is helpful in detecting ADHD-associated symptomatology in childhood. A German short version (WURS-k) of this instrument has been made available recently. In the present study, we investigated the validity of the WURS-k. In a population of 63 adult ADHD patients (according to ICD-10 and DSM-IV criteria) and 1,303 male controls, ROC analysis indicated a sensitivity of 85% and specificity of 76% at a cutoff of 30 points. In ADHD patients, seven individual factors explained 70.3% of the variance. The highest diagnostic precision was demonstrated using the WURS-k total score. The seven extracted factors of the WURS-k did not differ in diagnostic value. Significant correlations were found between impulsivity according to Eysenck's Impulsivity Questionnaire (EIQ) and excitability, aggression, emotional lability, and satisfaction on the Freiburg Personality Inventory (FPI-R) in ADHD patients. Concerning a 30-50% persistence of ADHD symptomatology in adults, these correlations underline the diagnostic validity of the WURS-k. The scale manifested excellent internal consistency (alpha=0.91) and a split-half correlation of r(12)=0.85.


Assuntos
Transtorno do Deficit de Atenção com Hiperatividade/diagnóstico , Transtorno do Deficit de Atenção com Hiperatividade/epidemiologia , Inventário de Personalidade/estatística & dados numéricos , Inventário de Personalidade/normas , Escalas de Graduação Psiquiátrica/estatística & dados numéricos , Escalas de Graduação Psiquiátrica/normas , Índice de Gravidade de Doença , Adulto , Transtorno do Deficit de Atenção com Hiperatividade/psicologia , Feminino , Alemanha , Humanos , Masculino , Valor Preditivo dos Testes , Reprodutibilidade dos Testes , Estudos Retrospectivos , Sensibilidade e Especificidade
3.
Nervenarzt ; 73(9): 830-8, 2002 Sep.
Artigo em Alemão | MEDLINE | ID: mdl-12215873

RESUMO

This work presents a statistical analysis of the German version of the Wender Utah rating scale (WURS) for the retrospective diagnosis of attention-deficit/hyperactivity disorder (ADHD) in adults. Data were obtained from 703 subjects. Item selection according to item-total correlation scores, frequency, and plausibility led to a short version of the scale that includes 21 items with item-total correlations from 0.19 to 0.61. Retest reliability of the WURS-k was r=0.9.


Assuntos
Transtorno do Deficit de Atenção com Hiperatividade/diagnóstico , Inventário de Personalidade/estatística & dados numéricos , Adolescente , Adulto , Idoso , Idoso de 80 Anos ou mais , Transtorno do Deficit de Atenção com Hiperatividade/psicologia , Criança , Comparação Transcultural , Feminino , Alemanha , Humanos , Masculino , Pessoa de Meia-Idade , Psicometria , Reprodutibilidade dos Testes , Estudos Retrospectivos
4.
Fortschr Neurol Psychiatr ; 69(10): 453-9, 2001 Oct.
Artigo em Alemão | MEDLINE | ID: mdl-11602921

RESUMO

The implications of ADHD for sexual delinquent behavior were investigated in a sample of 127 male sexual delinquents for whom social, forensic and psychiatric data were collected. For the retrospective evaluation of ADHD-symptoms, we used the Wender Utah Rating Scale (WURS, 61-item version). We also used the Eysenck Impulsiveness Questionnaire for the assessment of impulsivity. The prevalence of ADHD within the group of sexual delinquents was 27.6 % with a persistence rate of 14.2 % at a cut-off point of 90 in the WURS. The prevalence of ADHD within the control group was 7.8 % with a persistence rate of 3.0 %. The prevalence within the group of sexual delinquents dropped to 15.7 % for childhood ADHD-symptoms and 11.0 % for partial ADHD persistence in adulthood using a cut-off score of 100. In the control group the rates were 4.8 % and 2.4 % respectively. Based on ICD-10 criteria, 35.4 % of the sexual delinquents had no psychiatric disorder. We found personality disorders of the antisocial type (22.1 % of the sample) and paraphilias in 25.2 %. Approximately, half of the delinquents with paraphilia met the criteria of pedophilia. We also found schizophrenia, organic psychiatric disorders and mental retardations in less than 5 %. The criminal careers of the sexual delinquent group with a history of childhood ADHD symptoms started 10 years earlier. We also found a significant correlation between previous convictions and the retrospective diagnosis of ADHD symptoms. This was more prominent when a previous sexual offence could be found in their criminal record. These results illustrate the hypothesis, that in addition to paraphilias the presence of ADHD-symptoms might be an important vulnerability factor for sexual delinquency, esp. when there is a persistence into adulthood. This demonstrates the need for an early therapeutical intervention, since 44.1 % of the sample had previously undergone psychiatric treatment.


Assuntos
Transtorno do Deficit de Atenção com Hiperatividade/psicologia , Delitos Sexuais/psicologia , Adulto , Idoso , Transtorno do Deficit de Atenção com Hiperatividade/epidemiologia , Humanos , Testes de Inteligência , Masculino , Pessoa de Meia-Idade , Transtornos da Personalidade/epidemiologia , Transtornos da Personalidade/psicologia , Escalas de Graduação Psiquiátrica
5.
Nervenarzt ; 70(1): 20-5, 1999 Jan.
Artigo em Alemão | MEDLINE | ID: mdl-10087514

RESUMO

The attention-deficit hyperactivity disorder (ADHD) is one of the most common disorders in childhood and adolescence with a prevalence of app. 5%. The importance of ADHD in childhood as a factor of vulnerability for psychiatric disorders in adults is becoming a focus of discussion. It was shown that there is a comorbidity in adults with substance abuse, delinquency and personality disorders. There is a growing evidence that ADHD will persist in a significant number of patients during adulthood. This is the first german study to evaluate this interdependence. We examined 164 adult inpatients and 48 healthy volunteers with the Wender Utah Rating Scale (WURS), a retrospective self-evaluation scale for the diagnosis of ADHD in childhood, and the Eysenck impulsiveness questionnaire I7. It could be shown that the WURS and the I7 are suitable instruments for the evaluation of the ADHD in adults especially concerning the aspects of attention deficits and impulsiveness.


Assuntos
Transtorno do Deficit de Atenção com Hiperatividade/diagnóstico , Adulto , Idoso , Transtorno do Deficit de Atenção com Hiperatividade/epidemiologia , Feminino , Alemanha/epidemiologia , Humanos , Comportamento Impulsivo/diagnóstico , Comportamento Impulsivo/epidemiologia , Masculino , Pessoa de Meia-Idade , Transtornos Relacionados ao Uso de Substâncias/diagnóstico , Transtornos Relacionados ao Uso de Substâncias/epidemiologia
6.
Arch Biochem Biophys ; 294(2): 418-26, 1992 May 01.
Artigo em Inglês | MEDLINE | ID: mdl-1567197

RESUMO

The development and application of model membrane systems on the basis of tetraether lipids from Thermoplasma acidophilum has been proposed. In this respect incorporation of membrane proteins and ionophores is indispensable and is demonstrated in the case of alamethicin, melittin, nonactin, and valinomycin by calorimetry. Dipalmitoylphosphatidylcholine (DPPC) and dihexadecylmaltosylglycerol (DHMG) were chosen for comparison. Melittin and alamethicin prove to broaden the lipid phase transition and to reduce the melting temperature Tm and enthalpy change (delta H) of the main phospholipid from T. acidophilum (MPL) and DPPC. The decrease in Tm, however, is more pronounced in DPPC than in MPL. Valinomycin shows only a marginal effect on the temperature and width of the transition; delta H is reduced in MPL and remains constant in DPPC and DHMG. With nonactin the phase transition of DPPC is quenched, and delta H and the half-height width are increased. DHMG is affected to a lesser extent and MPL only marginally. The four ionophores exhibit different modulation of the phase transition behavior of the various lipids as expected from their varying molecular structures. Thus, the integral membrane protein alamethicin, the peripheral protein melittin, valinomycin, and nonactin interact primarily with lipid head groups and are readily incorporated into the tetraether lipid structures.


Assuntos
Alameticina/química , Antibacterianos/química , Meliteno/química , Éteres Fosfolipídicos/química , Thermoplasma/metabolismo , Valinomicina/química , 1,2-Dipalmitoilfosfatidilcolina/química , Sequência de Aminoácidos , Varredura Diferencial de Calorimetria/métodos , Éteres de Glicerila/química , Macrolídeos , Modelos Biológicos , Dados de Sequência Molecular , Éteres Fosfolipídicos/isolamento & purificação , Thermoplasma/crescimento & desenvolvimento
7.
Int J Radiat Biol ; 60(5): 791-802, 1991 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-1680950

RESUMO

Skin fibroblasts from ataxia telangiectasia (AT) patients, obligate AT heterozygotes (ATH) and normal individuals were studied for colony-forming ability and repair of DNA double-strand breaks (dsb) after gamma-irradiation. AT cells were three to four times more radiosensitive than normal cells at high and low dose-rate exposures; ATH cells, however, showed a marginally increased radiosensitivity after high dose-rate gamma-irradiation and an intermediate response after low dose-rate exposure. The repair of DNA dsb was studied by pulsed field gel electrophoresis. After high dose-rate gamma-irradiation the repair time constant (t1/2) was around 1 h for normal, ATH and AT cells. After low dose-rate gamma-irradiation the fraction of residual dsb was 1.4% for normal, 2.1% for ATH and 5.2% for AT cells, demonstrating a deficiency in the repair of a small fraction of dsb in AT. Thus the fraction of residual dsb after low dose-rate exposure was not only four times higher in AT than in normal cells, but was also significantly increased in ATH compared to normal cells.


Assuntos
Ataxia Telangiectasia/patologia , Dano ao DNA , DNA/efeitos da radiação , Heterozigoto , Ataxia Telangiectasia/genética , Sobrevivência Celular/efeitos da radiação , Radioisótopos de Cobalto , Reparo do DNA , Relação Dose-Resposta à Radiação , Eletroforese em Gel de Campo Pulsado , Fibroblastos/efeitos da radiação , Raios gama , Humanos
8.
Arch Biochem Biophys ; 290(1): 224-8, 1991 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-1898093

RESUMO

The main glycophospholipid from Thermoplasma acidophilum is composed of a diisopranol-2,3-glycerotetraether. The fraction of pentane cyclizations of its hydrocarbon chains increases with the growth temperature of the source organism (39-59 degrees C). Hydrated mixtures of these lipids together with cholesterol have been studied by calorimetry. With the reduction of the phase transition temperatures and enthalpy changes of the transitions, cholesterol is readily incorporated into lipid monolayers in the liquid-crystalline and the (metastable) solid-analogue phase. Lipid samples with a high number of acyclic hydrocarbon chains form a stable and a metastable solid-analogue phase. With the increasing concentration of cholesterol the metastable solid-analogue phase is stabilized and the time constant for the formation of the stable solid-analogue phase is prolonged.


Assuntos
Colesterol/metabolismo , Éteres Fosfolipídicos/metabolismo , Thermoplasma/metabolismo , Varredura Diferencial de Calorimetria , Lipídeos de Membrana/metabolismo , Fosfatidilgliceróis/metabolismo , Termodinâmica
9.
Biochim Biophys Acta ; 1065(2): 160-6, 1991 Jun 18.
Artigo em Inglês | MEDLINE | ID: mdl-2059650

RESUMO

Four analogues of the membrane-modifying, alpha-helical polypeptide antibiotic alamethicin were synthesized. the alpha-helical deca-, undeca-, heptadeca-, and icosapeptides were mixed with the main tetraether lipid of the Archaebacterium Thermoplasma acidophilum (MPL), dipalmitoylphosphatidylcholine (DPPC) and dihexadecylmaltosylglycerol (DHMG) in various ratios and the modification of the lipid phase transition was determined by differential thermal analysis (DTA). The polypeptides form mixed phases with MPL and DPPC, however, not with DHMG. Heptadeca- and icosapeptide exert a much stronger reduction of enthalpy (delta H) than deca- and undecapeptide and bind about 0.5 molecule of MPL (or one molecule of DPPC) per peptide molecule. delta H of the DPPC pretransition is reduced by the deca- and the undecapeptides and completely disappears with heptadeca- and icosapeptides (at 0.2 mole of peptide/mole of lipid). The modulation of the melting point Tm by the incorporation of peptides is more pronounced with MPL than with DPPC, the heptadecapeptide exhibiting the strongest reduction (with MPL) and the strongest broadening of the transition peak (with DPPC). Helix length, amphiphilicity and charge of the polypeptides can be correlated with the observed modifications of the lipid phase transitions.


Assuntos
Alameticina/análogos & derivados , Membrana Celular/metabolismo , Lipídeos de Membrana/metabolismo , Peptídeos/metabolismo , Thermoplasma/metabolismo , 1,2-Dipalmitoilfosfatidilcolina/metabolismo , Alameticina/metabolismo , Sequência de Aminoácidos , Varredura Diferencial de Calorimetria , Éteres de Glicerila/metabolismo , Dados de Sequência Molecular , Peptídeos/química , Conformação Proteica , Termodinâmica
10.
Cancer Lett ; 57(2): 137-43, 1991 May 01.
Artigo em Inglês | MEDLINE | ID: mdl-2025886

RESUMO

Cultured skin fibroblast cell lines from two non-Hodgkin's lymphoma patients (NHL) and a normal subject were studied for cell killing, chromosomal aberrations (breaks, translocations, dicentrics and rings) and DNA double strand breaks (dsbs) following chronic gamma irradiation. Compared to the cell line from the normal donor, the NHL patients' fibroblasts showed enhanced radiosensitivity for both cell survival and chromosomal aberrations. While spontaneous breaks were observed in both normal and patients' cells, spontaneous translocations and radiation-induced dicentrics and rings were found only in the latter. Radiation-induced DNA double-strand breaks (dsb) were determined by CHEF electrophoresis. After chronic irradiation with gamma rays the fraction of residual dsb was significantly increased from 1.4% in controls to 1.9% in the NHL cell lines. These data, thus, suggest that the cellular and chromosomal sensitivity to chronic irradiation observed in NHL patients may be due to a deficiency in the repair of a small fraction of DNA double strand breaks.


Assuntos
Dano ao DNA , DNA de Neoplasias/efeitos da radiação , Fibroblastos/efeitos da radiação , Linfoma não Hodgkin/metabolismo , Linhagem Celular/efeitos da radiação , Sobrevivência Celular/efeitos da radiação , Aberrações Cromossômicas , Reparo do DNA/efeitos da radiação , Relação Dose-Resposta à Radiação , Fibroblastos/ultraestrutura , Raios gama , Humanos , Linfoma não Hodgkin/ultraestrutura
11.
Int J Radiat Biol ; 59(4): 919-26, 1991 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-1674276

RESUMO

DNA fragments removed from the filter during non-denaturing filter elution were collected and loaded on top of neutral sucrose gradients. Their size distribution was determined by low-speed centrifugation in neutral sucrose gradients. The average size of eluted DNA was found to be approximately 110 S, yet the average size of DNA collected after short elution times was found to be slightly larger than that after long elution times. It is concluded that the size of eluted DNA fragments is not correlated with their elution rate, and it is proposed that shear forces generated at the pores of the filter cause degradation of the DNA. A comparison of the sedimentation profiles of carefully prepared cellular DNA before and after elution revealed that the generated shear forces during elution break down the DNA to an extent equivalent to around 20,000 DNA double-strand breaks (dsb) per G1 cell. The size of DNA fragments decreased with increasing radiation dose; however, five times more dsb were found than expected after exposure to radiation alone. It is proposed that this excess of dsb may derive from the transformation of other radiation-induced lesions to dsb under the action of the shear forces generated during elution.


Assuntos
DNA/isolamento & purificação , Desnaturação de Ácido Nucleico , Animais , Linhagem Celular , Células Cultivadas/efeitos da radiação , Centrifugação com Gradiente de Concentração/métodos , Cricetinae , Cricetulus , DNA/efeitos da radiação , Filtração/métodos , Masculino , Peso Molecular , Tamanho da Partícula , Fatores de Tempo
12.
Int J Radiat Biol ; 59(4): 927-39, 1991 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-1674277

RESUMO

The initial (up to 30 min) rate of DNA double-strand break (dsb) rejoining was measured in irradiated plateau-phase CHO cells, in a set of parallel experiments using the same cell suspension, by means of non-unwinding filter elution, neutral sucrose gradient centrifugation, and two pulsed-field gel electrophoresis assays: asymmetric field inversion gel electrophoresis (AFIGE) and clamped homogeneous electric field (CHEF) gel electrophoresis. The rate of DNA dsb rejoining was compared to the rate of rejoining of chromatin breaks measured, also in the same cell population, using the technique of premature chromosome condensation (PCC). Two radiation exposures, 25 Gy and/or 50 Gy, were used and applied to the individual parts of the experiments according to the sensitivity of the assay under investigation. Similar values for the initial rate of DNA dsb rejoining were obtained with all assays used, with t 1/2 ranging between 10 and 12 min after exposure to 25 Gy and between 15 and 20 min after exposure to 50 Gy. The initial rate of rejoining of chromatin breaks was slower than that of DNA dsb and occurred with t 1/2 of 87 min. The results suggest that all major techniques currently used for assaying rejoining of DNA dsb give similar results despite their widely different biophysical basis, and indicate that more information is required before a direct correlation between rejoining of DNA dsb and rejoining of chromatin breaks can be established.


Assuntos
Dano ao DNA/efeitos da radiação , DNA/efeitos da radiação , Animais , Linhagem Celular , Células Cultivadas/efeitos da radiação , Centrifugação com Gradiente de Concentração/métodos , Cromossomos/efeitos da radiação , Cricetinae , Cricetulus , DNA/análise , DNA/isolamento & purificação , Eletroforese em Gel de Ágar , Feminino , Filtração/métodos
13.
Radiat Res ; 123(2): 176-81, 1990 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-2389004

RESUMO

In neutral filter elution a nonlinear relationship between fraction of eluted DNA and dose is usually observed, which is often interpreted as a nonlinear induction of DNA double-strand breaks (DSBs) with dose. The conclusiveness of this hypothesis is questioned here on the basis of theoretical considerations regarding the size distribution of DNA fragments. A simple hydrodynamic model is proposed which generates the typical features of the dose response of neutral filter elution: (1) the shoulder at low doses, (2) a quasilinear correlation in an intermediate dose range, (3) a saturation at high doses, and (4) a linearization of the curve in the intermediate and higher dose range in a semilogarithmic plot. These features were derived even with the assumption of a linear induction of DSBs with dose. Thus it is demonstrated that the fraction of eluted DNA could conceivably be a nonlinear function of dose even if the induction of DSBs is directly proportional to the radiation dose.


Assuntos
DNA/efeitos da radiação , Reparo do DNA , Relação Dose-Resposta à Radiação , Filtração/métodos
14.
Int J Radiat Biol ; 58(1): 23-34, 1990 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-1973438

RESUMO

Pulsed-field gel electrophoresis (PFGE) has become a powerful tool for the study of high-molecular-weight DNA. In this technical note the application of clamped homogeneous electrical field (CHEF) electrophoresis for the determination of DNA double-strand breaks is described, and a number of parameters that influence the sensitivity of the assay are discussed. They include the concentration of the cell sample, agarose concentration in the plug and the electrophoresis gel, lysis conditions, pulse time, electric field gradient and the temperature of electrophoresis.


Assuntos
Dano ao DNA , DNA/efeitos da radiação , Animais , Cricetinae , Eletroforese/métodos , Técnicas In Vitro
15.
Biochim Biophys Acta ; 1024(1): 54-60, 1990 May 09.
Artigo em Inglês | MEDLINE | ID: mdl-2337621

RESUMO

The main glycophospholipid of Thermoplasma acidophilum, grown at 39 degrees C, is composed of a di-isopranol-2,3-glycerotetraether. It has been characterized in hydrated systems by calorimetry. Unlike its equivalent grown at 59 degrees C, it shows complex phase properties, which include at least three different phases, (1) a liquid-analogue state (C), which is stable above 20 degrees C, (2) a metastable solid-analogue state (A) formed by supercooling of the liquid-analogue state (C) and (3) a stable solid-analogue state (B), which is slowly formed and may include a close chain packing of lipids and a network of hydrogen bonds between the headgroups. A high fraction of acyclic isopranol chains seems to be a prerequisite for the formation of state (B). A phase diagram, displaying the observed states and the transitions between them is proposed.


Assuntos
Glicolipídeos , Lipídeos de Membrana , Fosfolipídeos , Thermoplasma/fisiologia , Calorimetria , Fenômenos Químicos , Físico-Química , Éteres , Temperatura Alta , Concentração de Íons de Hidrogênio , Relação Estrutura-Atividade , Termodinâmica
16.
Int J Radiat Biol ; 57(1): 7-12, 1990 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-1967296

RESUMO

A theory for DNA double-strand break (dsb) analysis by pulsed field electrophoresis is presented, based on the size distribution of DNA fragments, which converts an induction of dsb linear with dose into a nonlinear fraction of extractable DNA, in agreement with experimental observations.


Assuntos
DNA/análise , DNA/efeitos da radiação , Eletroforese/métodos , Animais , Cricetinae , Técnicas In Vitro
17.
Int J Radiat Biol ; 56(6): 869-75, 1989 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-2574216

RESUMO

We have observed that low gamma-ray doses regularly improve the survival (plating efficiency) above that of unirradiated control cultures, which we postulate could arise through inducible DNA repair, and would have profound effects on the interpretation of cell culture experiments.


Assuntos
Sobrevivência Celular/efeitos da radiação , Animais , Linhagem Celular , Chlorocebus aethiops , Radioisótopos de Cobalto , Relação Dose-Resposta à Radiação , Raios gama , Humanos
18.
Int J Radiat Biol ; 56(4): 437-48, 1989 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-2571657

RESUMO

It has been demonstrated that clamped homogeneous electrical field (CHEF) electrophoresis is a suitable method for the determination of DNA double-strand breaks in Chinese hamster ovary (CHO) cells. It allows the separation of DNA molecules up to 10 Mbp. The fraction of DNA fragments of this size is correlated with the number of radiation induced double-strand breaks. The resolution limit of the technique is equivalent to the effect of about 1 Gy (gamma-rays). Double-strand break repair was monitored after irradiation with Co-60 gamma rays and the repair time constant determined to t1/2 = 30-35 min. In combination with the detection of DNA by fluorescence, CHEF electrophoresis provides an easy and sensitive method for the determination of double-strand break repair which does not require the radioactive labelling of cells.


Assuntos
Dano ao DNA , DNA/efeitos da radiação , Eletroforese em Gel de Ágar/métodos , Animais , Linhagem Celular , Cricetinae , DNA/análise , Reparo do DNA , Relação Dose-Resposta à Radiação , Eletroforese , Raios gama , Fatores de Tempo
19.
Int J Radiat Biol ; 54(5): 761-71, 1988 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-2902170

RESUMO

Radiation-induced DNA double-strand breaks (dsb) were studied in Ehrlich ascites tumour cells (EATC) by sedimentation in neutral sucrose gradients at low centrifuge speed. Dsb induction was found to be linear with dose with a frequency of: ndsbmr-1D-1 = (11.7 +/- 2) x 10(-12)Gy-1 for 140 kV X-rays and ndsbmr-1D-1 = (19.1 +/- 4) x 10(-12)Gy-1 for 3.4 MeV 241Am-alpha-particles. Postirradiation incubation of cells under non-growth conditions leads to repair of dsb, reaching a maximum after trep = 24 h. More than 97 per cent of dsb were repaired after an X-ray dose of 25 Gy. The number of residual dsb was found to be a linear-quadratic function of dose: nresmr-1 = (0.0161 +/- 0.0008) x 10(-12)Gy-2D2 for X-rays and nresmr-1 = (1.2 +/- 0.7) x 10(-12)Gy-1D + (0.105 +/- 0.017) x 10(-12)Gy-2D2 for alpha-particles. Thus, after cellular repair the RBE value of alpha-particles was increased from RBE = 1.6 +/- 0.4 (induction of dsb) to a dose-dependent value of RBE = 2.7 +/- 0.4 (at 100 Gy alpha-particles) to 3.8 +/- 1.2 (at 10 Gy alpha-particles) for residual dsb. From the data presented it is concluded that residual dsb are a major cause for loss of the reproductive capacity of EATC after irradiation with X-rays as well as alpha-particles.


Assuntos
Partículas alfa , Dano ao DNA , Reparo do DNA/efeitos da radiação , DNA de Neoplasias/efeitos da radiação , Animais , Carcinoma de Ehrlich , DNA/efeitos da radiação , Eficiência Biológica Relativa , Células Tumorais Cultivadas/efeitos da radiação
SELEÇÃO DE REFERÊNCIAS
DETALHE DA PESQUISA
...