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In this study, we aimed to compare the efficiency of Tönnis and the novel International Hip Dysplasia Institute (IHDI) in decision making and in presuming the outcomes in children who had undergone closed reduction and casting. 406 hips of 298 patients who had undergone closed reduction and spica casting were included in this retrospective study. All hips were classified according to Tönnis and IHDI systems. Bucholz-Ogden classification was used for avascular necrosis. The outcomes of patients for each classification system were compared, in terms of the presence of avascular necrosis, redislocations and secondary surgeries at the end of the follow-up period. 318 hips were evaluated as Tönnis grade 2 dysplasia. 24 had avascular necrosis, 9 had redislocations. 79 hips were evaluated as Tönnis grade 3 dysplasia. 18 had AVN, 7 had redislocations. 9 hips were evaluated as Tönnis grade 4 dysplasia 3 had AVN, 4 had redislocations. 203 patients were evaluated as IHDI grade 2 dysplasia. 7 had AVN, 7 had redislocations.185 patients were assessed as IHDI grade 3 dysplasia. 33 had AVN, 11 had redislocations. 18 patients were evaluated as IHDI grade 4 dysplasia. 5 had AVN, 6 had redislocations. Both Tönnis classification and IHDI classification systems are reliable and efficient systems for evaluating the severity and predicting the success of closed reduction and casting for the treatment of DDH. IHDI classification has certain benefits, such as being a practical classification and a better distribution within the groups.
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Displasia del Desarrollo de la Cadera , Luxación Congénita de la Cadera , Procedimientos Ortopédicos , Osteonecrosis , Niño , Humanos , Lactante , Luxación Congénita de la Cadera/diagnóstico por imagen , Estudios Retrospectivos , Displasia del Desarrollo de la Cadera/diagnóstico por imagen , Displasia del Desarrollo de la Cadera/cirugía , Displasia del Desarrollo de la Cadera/etiología , Procedimientos Ortopédicos/efectos adversos , Osteonecrosis/cirugía , Resultado del TratamientoRESUMEN
Introduction: The appraisal of disease severity and prediction of adverse outcomes using risk stratification tools at early disease stages is crucial to diminish mortality from coronavirus disease 2019 (COVID-19). While lung ultrasound (LUS) as an imaging technique for the diagnosis of lung diseases has recently gained a leading position, data demonstrating that it can predict adverse outcomes related to COVID-19 is scarce. The main aim of this study is therefore to assess the clinical significance of bedside LUS in COVID-19 patients who presented to the emergency department (ED). Methods: Patients with a confirmed diagnosis of SARS-CoV-2 pneumonia admitted to the ED of our hospital between March 2021 and May 2021 and who underwent a 12-zone LUS and a lung computed tomography scan were included prospectively. Logistic regression and Cox proportional hazard models were used to predict adverse events, which was our primary outcome. The secondary outcome was to discover the association of LUS score and computed tomography severity score (CT-SS) with the composite endpoints. Results: We assessed 234 patients [median age 59.0 (46.8-68.0) years; 59.4% M), including 38 (16.2%) in-hospital deaths for any cause related to COVID-19. Higher LUS score and CT-SS was found to be associated with ICU admission, intubation, and mortality. The LUS score predicted mortality risk within each stratum of NEWS. Pairwise analysis demonstrated that after adjusting a base prediction model with LUS score, significantly higher accuracy was observed in predicting both ICU admission (DBA -0.067, P = .011) and in-hospital mortality (DBA -0.086, P = .017). Conclusion: Lung ultrasound can be a practical prediction tool during the course of COVID-19 and can quantify pulmonary involvement in ED settings. It is a powerful predictor of ICU admission, intubation, and mortality and can be used as an alternative for chest computed tomography while monitoring COVID-19-related adverse outcomes.
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COVID-19 , Humanos , Persona de Mediana Edad , COVID-19/complicaciones , COVID-19/diagnóstico por imagen , SARS-CoV-2 , Sistemas de Atención de Punto , Pulmón/diagnóstico por imagen , Ultrasonografía/métodos , Tomografía Computarizada por Rayos XRESUMEN
BACKGROUND: Many unknown risk factors play a role in the etiopathogenesis of stroke. The appearance of inflammatory cells within the damaged tissue after cerebral ischemia suggests that an inflammatory response may play a role in stroke pathogenesis. In our study, we examined whether an association exists between the acute-phase reactants and the levels of cytokines, the volume and diameter of the stroke, and short-term mortality in patients who were diagnosed as acute ischemic a stroke after admission to the Emergency Department. PATIENTS AND METHODS: A total of 50 consecutive patients who applied to the Emergency Service with acute ischemic stroke were enrolled in the study. Their stroke volume were calculated and serum samples were obtained as soon as they arrived into the Emergency Service. The patients were evaluated according to the Glasgow Coma Scale (GCS) and National Institutes of Health Stroke Scale (NIHSS). RESULTS: There was no significant correlations between stroke volume and levels of cytokine and acute-phase reactants in dead patient group or in living patient group. A correlation and statistical significance was found between stroke volume and hospital stay time in living patient group. In addition, GCS and NIHSS scores were correlated with stroke volume and was found a significant statistically. CONCLUSIONS: Scales such as GKS and NIHHS, which evaluate the functional state of patients, are the best indicators for defining prognosis in our daily practices. In addition, we found a positive correlation between levels of CRP (C reactive protein) and prognosis. However, we did not observe a statistically significant correlation between prognosis and other acute-phase reactants such as TNF-alpha, IL-6, IL-8, IL-10, fibrinogen, and leukocytes.
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Isquemia Encefálica/mortalidad , Proteína C-Reactiva/análisis , Citocinas/sangre , Accidente Cerebrovascular/mortalidad , Adulto , Anciano , Isquemia Encefálica/sangre , Isquemia Encefálica/etiología , Femenino , Escala de Coma de Glasgow , Humanos , Masculino , Persona de Mediana Edad , Estudios Prospectivos , Factores de Riesgo , Accidente Cerebrovascular/sangre , Accidente Cerebrovascular/etiologíaRESUMEN
Nae I endonuclease must bind to two DNA sequences for cleavage. Examination of the amino acid sequence of Nae I uncovered similarity to the active site of human DNA ligase I, except for leucine 43 in Nae I instead of the lysine essential for ligase activity. Changing leucine 43 to lysine 43 (L43K) changed Nae I activity: Nae I-L43K relaxed supercoiled DNA to yield DNA topoisomers and recombined DNA to give dimeric molecules. Interruption of the reactions of Nae I and Nae I-L43K with DNA demonstrated transient protein-DNA covalent complexes. These findings imply coupled endonuclease and ligase domains and link Nae I endonuclease to the topoisomerase and recombinase protein families.
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ADN Nucleotidiltransferasas/metabolismo , ADN-Topoisomerasas de Tipo I/metabolismo , Desoxirribonucleasas de Localización Especificada Tipo II/metabolismo , Integrasas , Secuencia de Aminoácidos , Sitios de Unión , ADN Circular/metabolismo , Desoxirribonucleasas de Localización Especificada Tipo II/química , Datos de Secuencia Molecular , Mutagénesis Sitio-Dirigida , Recombinasas , Homología de Secuencia de AminoácidoRESUMEN
Scorpions are nocturnal arthropods that inject their venom through the victims' skin by stingers. By the envenomation, clinical manifestations in a wide spectrum may occur, including pain at one side and death because of severe cardiopulmonary or neurological abnormalities. Sometimes the victim cannot describe the insect or does not remember even being stung after the event. We present two cases of scorpion envenomation with different and rare clinical situations with a short review of the literature.
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Picaduras de Escorpión/diagnóstico , Adulto , Analgésicos Opioides/uso terapéutico , Animales , Antivenenos/uso terapéutico , Recuento de Células Sanguíneas , Análisis Químico de la Sangre , Ecocardiografía , Electrocardiografía , Femenino , Fentanilo/uso terapéutico , Fiebre/tratamiento farmacológico , Fiebre/etiología , Humanos , Masculino , Miocardio/enzimología , Dolor/tratamiento farmacológico , Picaduras de Escorpión/fisiopatología , Picaduras de Escorpión/terapia , Venenos de Escorpión , EscorpionesRESUMEN
Background and objectives: Bipolar disorder (BD) is a clinical status with at least one manic, hypomanic or mixed attacks. Genetic factors take part significantly in early-onset BD (EOBD). Dopamine receptors (DRD) act in neurological mechanisms like motivation, learning, memory, and, control of neuroendocrine signaling. DRD2 receptor has been reported to influence the stability of DRD2 transcript. Catechol-O-Methyl transferase (COMT) inactivates catecholamines and Val158Met variation on COMT has effects on COMT activity. This study aims to explore DRD2 and COMT variants in the clinical development of EOBD.MethodsIn this case-control study, 102 EOBD patients and 168 healthy control subjects were used. DRD2 rs6275 and COMT Val158Met variations were detected by real-time polymerase chain reaction (RT-PCR). Young Mania Rating Scale (YMRS) was utilized to determine the EOBD severity.ResultsFor DRD2 rs6275 and COMT Val158Met polymorphisms, no significant relationship was observed in the genotype and allele frequencies between patient and control groups. Nevertheless, TT genotype carriers of DRD2 rs6275 polymorphism demonstrated significantly increased YMRS scores when compared with CC and CT genotype carriers (p = 0.039). Nevertheless, no significant difference was observed between COMT Val158Met genotypes and YMRS scores.ConclusionsWe suggest that the DRD2 rs6275 TT variant can be associated with symptom severity in children with EOBD and can have a clinical significance in EOBD pathogenesis. However, these results need to be confirmed with larger samples of patient and control groups. (AU)
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Humanos , Trastorno Bipolar , Receptores Dopaminérgicos , Aprendizaje , Memoria , CatecolaminasRESUMEN
Abstract Background and Objectives. To investigate the clinical characteristics of adolescents with early-onset full psychotic disorders either with Brain-derived neurotrophic factor (BDNF) Val66Met (rs6265) or DRD2/ANKK1 Taq1A (rs1800497) polymorphisms.
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Humanos , Adolescente , Ciencias de la Salud , Psiquiatría del Adolescente , Esquizofrenia/genéticaRESUMEN
OBJECTIVE: To evaluate medical and surgical residents' anger levels with regard to the department in which they worked, seniority, sex, satisfaction with their work environment, and the number of nightshifts worked per month. The specific situations and persons at whom residents reacted with anger were also investigated. METHODS: 116 randomly selected residents staffed in a university hospital (62 medical and 54 surgical residents) were enrolled. The trait anger and anger expression scale was used to find out the personal anger levels of each participant. The participants also clarified the persons and situations that made them angry at work. RESULTS: Trait anger levels were greater in the surgical residents in their first two years when compared with levels of their senior colleagues (p = 0.033). Mean trait anger levels were greater in the residents who were not satisfied with their department (p = 0.004). Anger levels were not found to be related to the number of shifts per month. Male residents had higher levels of anger than female colleagues (p = 0.019). CONCLUSION: Residents in clinical sciences seem to have the potential to benefit from a screening process in terms of anger and its subcomponents by means of a tool such as the trait anger and anger expression scale during their residency.
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Ira , Cirugía General , Cuerpo Médico de Hospitales/psicología , Estudiantes de Medicina/psicología , Adulto , Actitud del Personal de Salud , Recolección de Datos , Femenino , Humanos , Internado y Residencia , Masculino , Percepción , Factores Sexuales , TurquíaRESUMEN
Of the two cell types it was possible to culture from the dissociated rat liver, hepatocytes and Kupffer cells, only the former were fibrinolytically active. Rat hepatocytes during the first 24 hr in culture secreted two plasminogen activators with molecular weights identical to those found in rat plasma, an 80,000-dalton form (PA-80) and a 45,000-dalton form (PA-45). Partially purified preparations of plasminogen activators from both sources were subjected to isoelectric focusing (IEF) to compare characteristics further. There were three distinct peaks of PA-45 in each preparation with isoelectric points of 7.1, 7.2 and 7.4; all electrophoretic forms had the same low affinity to fibrin. PA-80 from both sources displayed similar IEF profiles with forms ranging from pH values of 7 to 8, all with the same high affinity to fibrin. The major form of PA-80 in the plasma preparation had an isoelectric point of 7.9 whereas that in the hepatocyte preparation had an isoelectric point of 7.6. The isolated perfused rat liver was also shown to produce both PA-80 and PA-45 emphasizing the physiological relevance of the findings with hepatocytes. It is concluded that in the rat hepatocytes contribute to the plasma profile with regard to the plasminogen activator content.
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Hígado/análisis , Activadores Plasminogénicos/análisis , Animales , Células Cultivadas , Electroforesis en Gel de Poliacrilamida , Fibrina/metabolismo , Técnicas In Vitro , Peso Molecular , Perfusión , Activadores Plasminogénicos/sangre , Ratas , Ratas EndogámicasRESUMEN
The cellular DNA precursor pool was shown to be a target for N-methyl-N-nitrosourea, a potent mutagen and carcinogen. O6medGTP, a product of this interaction, was chemically synthesized and shown to be incorporated into DNA in vitro by Klenow E. coli pol I and phage T4 DNA polymerases. O6medGTP incorporated predominantly opposite T template residues and to a lower extent opposite C. At some loci incorporation of O6medGTP caused DNA synthesis arrest. The significance of the behavior of O6medGTP for mutagenesis in vivo is discussed.
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ADN/biosíntesis , Mutación , Precursores de Ácido Nucleico/metabolismo , Alquilación , Composición de Base , Secuencia de Bases , ADN Polimerasa Dirigida por ADN/metabolismo , Nucleótidos de Desoxicitosina/metabolismo , Nucleótidos de Desoxiguanina/metabolismo , Desoxirribonucleótidos/metabolismo , Metilación , Metilnitrosourea/farmacología , Moldes GenéticosRESUMEN
9-Aminoacridine was found to inhibit dNTP incorporation into DNA homopolymer duplexes by phage T4 DNA polymerase in vitro. Systematic variation of the molar ratio of 9-aminoacridine to DNA, to DNA polymerase, and to DNA precursors demonstrated that this inhibition at 9-aminoacridine concentrations below 10 microM was mainly due to interaction of 9-aminoacridine with the DNA and suggested that the basis for the preferential inhibition of incorrect precursor incorporation was destabilization of the DNA growing point. Consistent with destabilization, 9-aminoacridine stimulated the hydrolysis of correctly base paired DNA by the 3'-5' exonuclease activity of phage T4 DNA polymerase. This is the first indication to my knowledge that an intercalating dye destabilizes the DNA growing point, whereas it raises the overall Tm of the DNA. At 9-aminoacridine concentrations above 10 microM overall incorporation of dNTPs was inhibited by 9-aminoacridine interaction with the DNA polymerase. A possible explanation for the induction of both deletion and addition frameshift mutations by 9-aminoacridine during DNA biosynthesis is discussed in light of growing-point destabilization.
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Aminacrina/toxicidad , Aminoacridinas/toxicidad , Replicación del ADN/efectos de los fármacos , Mutágenos , Mutación , Inhibidores de la Síntesis del Ácido Nucleico , ADN/genética , Desoxirribonucleótidos/metabolismo , Escherichia coli/enzimología , Cinética , Desnaturalización de Ácido Nucleico , Polidesoxirribonucleótidos , Fagos T/enzimología , TermodinámicaRESUMEN
On the basis of chemical considerations and model building, the Watson-Crick concept of complementary base pairing is extended to a wider range of DNA pairs that A-T and G-C (including A-C, G-T, A-A, G-G and G-A) by invoking imino or enol tautomers (or protonated species) and synisomers. The virtual absence of these additional base pairs from DNA is explained in terms of the low frequency with which these unfavoured forms occur and the two-step mechanism of DNA synthesis, whereby residues are first incorporated by the DNA polymerase and then checked. This base-pairing hypothesis is used to explain the origin, nature and level of spontaneous substitution mutations, their enhancement by base analogues, and the unique effects of certain mutator alleles.
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ADN , Modelos Biológicos , Mutación , 2-Aminopurina/metabolismo , Bromodesoxiuridina/metabolismo , Fenómenos Químicos , Química , ADN Nucleotidiltransferasas/metabolismo , Replicación del ADN , Exonucleasas/metabolismo , Enlace de Hidrógeno , Moldes GenéticosRESUMEN
Base pairing in codon-anticodon interaction has been investigated in order to understand the basis on which particular base pairs have been selected for or against participation at the wobble position and the basis for codon-anticodon infidelity.
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Anticodón , Codón , Biosíntesis de Proteínas , ARN Mensajero , ARN de Transferencia , Adenina , Enlace de Hidrógeno , Inosina , Modelos Biológicos , Conformación Molecular , Conformación de Ácido Nucleico , Ribosomas/metabolismo , AguaRESUMEN
The interactions of restriction enzymes with their cognate DNA recognition sequences present a model for protein-DNA interactions. We have investigated the effect of O6-methylguanine on restriction enzyme cleavage of DNA; O6-methylguanine is a carcinogenic lesion and a structural analogue of the biological restriction inhibitor N6-methyladenine. O6-Methylguanine was synthesized into oligonucleotides at unique positions. The oligonucleotides were purified and analyzed by high-pressure liquid chromatography to assure that, within the limits of our detection, O6-methylguanine was the only modified base present. These oligonucleotides were annealed with their complement so that cytosine, and in one case thymine, opposed O6-methylguanine. DNA cleavage by restriction enzymes that recognize a unique DNA sequence, HpaII, HhaI, HinPI, NaeI, NarI, PvuII, and XhoI, was inhibited by a single O6-methylguanine in place of guanine (adenine for PvuII) within the appropriate recognition sequences. However, only the modified strand was nicked by HpaII, NaeI, and XhoI with O6-methylguanine at certain positions, indicating asymmetric strand cleavage. For all the restriction enzymes studied but AhaII, BanI, and NarI, lack of double- or single-strand cleavage correlated with inability of the O6-methylguanine-containing recognition sequence to measurably bind enzyme. None of the restriction enzymes studied were inhibited by O6-methylguanine outside their cognate recognition sequences.
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Enzimas de Restricción del ADN/metabolismo , ADN de Cadena Simple/metabolismo , ADN/metabolismo , Guanina/análogos & derivados , Guanina/metabolismo , Secuencia de Bases , Cromatografía Líquida de Alta Presión , Electroforesis en Gel de Poliacrilamida , Datos de Secuencia Molecular , Oligodesoxirribonucleótidos/metabolismoRESUMEN
Cleavage of DNA by NaeI-type restriction enzymes is stimulated by a DNA element with affinity for the activator site of the enzyme: a cleavage-enhancer DNA element. Measurements of the mobility of NaeI activity in comparison with protein standards on gel permeation columns and glycerol gradients demonstrated that NaeI, without enhancer, can form a 70,000 MW dimer. The dimer, however, is inactive: it could not cleave the "resistant" NaeI site in M13mp18 DNA in the absence of enhancer. In cleavage assays, enhancer stimulated either DNA nicking or DNA cleavage, depending upon NaeI concentration, and reduced the NaeI concentration required for the transition from nicking to cleavage activity. A gel mobility-shift assay of the interaction of NaeI with enhancer showed the formation of two complexes. Results using different sized DNAs and different percentage acrylamide gels for gel mobility-shift analysis implied that the two complexes were caused by NaeI monomer and dimer structures rather than one and two DNA binding. Dimer formation increased with the affinity of enhancer for NaeI. UV cross-linking "captured" the NaeI-enhancer complex; electrophoretic analysis of the cross-linked products showed NaeI dimer bound to enhancer. These results imply a model for cleavage enhancement in which enhancer binding stabilizes an active NaeI dimer conformation ("cleavasome") that cleaves both DNA strands before dissociating.
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ADN/química , Desoxirribonucleasas de Localización Especificada Tipo II/metabolismo , Elementos de Facilitación Genéticos , Conformación de Ácido Nucleico , Secuencia de Bases , Sitios de Unión , ADN/metabolismo , Electroforesis en Gel de Poliacrilamida , Sustancias Macromoleculares , Datos de Secuencia Molecular , Peso Molecular , Secuencias Repetitivas de Ácidos Nucleicos , Rayos UltravioletaRESUMEN
Endonuclease EcoRII is one of a group of type II restriction enzymes, including Nael, Narl, BspMI, HpaII, and SacII, that require binding of an enhancer sequence to cleave DNA. Comparison of the EcoRII amino-acid sequence with the amino-acid consensus motifs that differentiate between recombinase families uncovered similarity between a 29 amino-acid sequence in the carboxyl end of EcoRII and the motif defining the integrase family of recombinases. This similarity implied that EcoRII tyrosine 308 should be involved in catalyzing hydrolysis of the scissile bond. Site-directed mutagenesis was used to mutate Tyr308 to Phe. The phenylalanine-substituted enzyme could not cleave T5 DNA under conditions in which wild-type enzyme completely cleaved this DNA. The Tyr308 to Phe mutation abolished cleavage activity but not specific binding to DNA. No evidence was found for the existence during the cleavage reaction of a covalent linkage between Tyr308 and DNA.
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ADN Nucleotidiltransferasas/genética , Desoxirribonucleasas de Localización Especificada Tipo II/genética , Desoxirribonucleasas de Localización Especificada Tipo II/metabolismo , Integrasas , Mutagénesis Sitio-Dirigida , Tirosina , Secuencia de Aminoácidos , Secuencia de Bases , Enzimas de Restricción del ADN/genética , Enzimas de Restricción del ADN/metabolismo , Datos de Secuencia Molecular , Oligodesoxirribonucleótidos , Plásmidos , Proteínas Recombinantes/metabolismo , Recombinasas , Homología de Secuencia de Aminoácido , Especificidad por SustratoRESUMEN
Mismatched and modified base pairs are central to questions of DNA mutation and repair. NMR and X-ray crystallography of mispairs indicate little to no local helical distortion, but these techniques are not sensitive to more global distortions of the DNA molecule. We used polyacrylamide gel electrophoresis and thermal denaturation to examine A.C, G.T, and O6-methylG.T and O6-methylG.C mismatches synthesized in place of either of two adjacent G.C base pairs in synthetic DNA duplexes. Substitution for G.C at either position decreased the stability of the duplex; O6-methylguanine was more destabilizing in place of the 5'G than in place of the 3'G. Comparisons between polymers synthesized so that lesions occurred regularly spaced on the same side of the helix and polymers synthesized so that the lesions alternated from side to side on the helix showed that these lesions introduced helical distortion composed of (i) a symmetric frictional component, probably caused by localized bubble formation, and (ii) an asymmetric component indicative of a more global effect on the DNA molecule. Comparisons between these effects at the two adjacent positions show that the extent of structural perturbation depends on sequence context.
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ADN Viral/efectos de los fármacos , Guanina/análogos & derivados , Mutación , Composición de Base , Secuencia de Bases , Electroforesis en Gel de Poliacrilamida , Guanina/farmacología , Datos de Secuencia Molecular , Conformación de Ácido Nucleico , Desnaturalización de Ácido Nucleico , Fagos T/genética , TemperaturaRESUMEN
Endonuclease NaeI is a prototype for an unusual group of type II restriction endonucleases that must bind two DNA recognition sequences to cleave DNA. The naeIR gene, expressed from a Ptac promotor construct, was toxic to Escherichia coli in the absence of NaeI-sequence specific methylases. The naeIR gene was mutagenized with N-methyl-N'-nitrosoguanidine; four classes of NaeI variants were isolated in the absence of protecting methylase activity. Class I variants (T60I, E70K) lacked detectable cleavage activity, but displayed good sequence-specific DNA binding. Class II variants (D95N, G141D) displayed 1-5% of the wild-type cleavage activity and normal DNA binding. Class III variants (G131E, G131R, G155D, G245E) displayed significantly attenuated cleavage and binding activities. Class IV variants (G197D, G214R/A219T, G236S, L241P, G245E, G245R, G250E, G270E) lacked both cleavage and binding activities. These results imply two amino acids (Thr-60, Glu-70) essential for catalysis. In addition, two domains are indicated in NaeI: one (Thr-60 to Gly-155) mediates substrate binding and catalysis, the other (Gly-197 to Gly-270) may mediate binding of the activating DNA sequence. Our results are compared with the active site residues of EcoRI, EcoRV, and BamHI.
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Desoxirribonucleasas de Localización Especificada Tipo II/metabolismo , Secuencia de Aminoácidos , Secuencia de Bases , Catálisis , Cartilla de ADN/química , Proteínas de Unión al ADN/química , Desoxirribonucleasas de Localización Especificada Tipo II/química , Datos de Secuencia Molecular , Mutagénesis , Nocardia/enzimología , Especificidad por SustratoRESUMEN
The ability of 9-aminoacridine to induce mutagenic lesions during DNA replication in vitro was investigated. The ampicillinase gene of pBR322 was replicated in vitro in the presence of 9-aminoacridine. Transfection of the replicated DNA into Escherichia coli gave Amps mutants. Determination of the base changes in 76 of these mutants indicated that the spectrum of mutations induced by 9-aminoacridine was consistent with its action in vivo. Both large (407-base) and small (1- and 2-base) deletions were induced at repetitive sequences. The frequency of deletion mutations depended on the identity of the base deleted and sequences surrounding the deletions. The characteristics of the frameshift mutations induced were consistent with the interactions of 9-aminoacridine with DNA. These results establish that 9-aminoacridine can induce frameshift mutations during the replication process and provide an in vitro model of frameshift induction for mechanistic studies.