RESUMO
Objective: To evaluate the significance of serum 8-hydroxy-deoxyguanosine acid(8-OHdG) in the diagnosis of nonalcoholic steatohepatitis (NASH). Methods: Patients or healthy subjects were enrolled at the Second Hospital of Tianjin Medical University and the Second People's Hospital of Tianjin from May 2013 to December 2015. A total of 41 patients with nonalcoholic fatty liver disease were enrolled in the study, including 20 nonalcoholic simple fatty liver (NAFL) patients and 21 NASH patients whose diagnosis were proven by liver biopsy. The other 32 healthy subjects were studied as controls. Serum 8-OHdG, ALT, AST and GGT were tested. Nonalcoholic fatty liver disease activity score (NAS) and expression of 8-OHdG in liver was investigated between NAFL patients and NASH patients. The correlations between serum 8-OHdG and serum ALT, AST, GGT, and 8-OHdG in liver tissue in NASH group were investigated. In addition, the receiver operating characteristic (ROC) curve analyses for ALT and 8-OHdG levels were performed in NAFL patients and NASH patients, and the cut-off value was determined. Results: Serum 8-OHdG values in healthy controls, NAFL and NASH patients were (0.19±0.16) µg/L, (0.22±0.16) µg/L, (0.42±0.21) µg/L respectively. The serum 8-OHdG and serum ALT, GGT and 8-OHdG in liver tissue were all positively correlated in NASH group with respective correlation coefficient r values as 0.454 7, 0.382 9, and 0.497 6. AUC of 8-OHdG was 0.901 with cut-off value 0.39 µg/L. Its sensitivity was 88.3% and specificity was 81.5%, which were higher than those of ALT. Conclusion: The value of serum 8-OHdG would be used as a marker for the diagnosis of NASH.
Assuntos
Biomarcadores/sangue , Desoxiguanosina/análogos & derivados , Fígado Gorduroso/patologia , Hepatopatia Gordurosa não Alcoólica/diagnóstico , 8-Hidroxi-2'-Desoxiguanosina , Adulto , Biópsia , Estudos de Casos e Controles , Desoxiguanosina/sangue , Desoxiguanosina/metabolismo , Fígado Gorduroso/sangue , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Hepatopatia Gordurosa não Alcoólica/sangue , Curva ROC , Sensibilidade e EspecificidadeRESUMO
The lantibiotic mutacin II, produced by Streptococcus mutans T8, is a ribosomally synthesized peptide antibiotic that contains thioether amino acids such as lanthionine and methyllanthionine as a result of post-translational modifications. The mutacin II leader peptide sequence shares a number of identical amino acid residues with class AII lantibiotic leader peptides. To study the role of these conservative residues in the production of active antimicrobial mutacin, 15 mutations were generated by site-directed mutagenesis. The effects of these substitutions vary from no effect to complete block-out. Mutations G-1A, G-2A, I-4D, and L-7K completely blocked the production of mature mutacin. Other mutations (I-4V, L-7M, E-8D, S-11T/A, V-12I/A, and E-13D) had no detectable effect on mutacin production. The changes of Glu-8 to Lys, Val-12 to Leu, Glu-13 to Lys reduced the mutacin production level to about 75%, 50%, and 10% of the wild-type, respectively. Thus, our data indicated that some of these conserved residues are essential for the mutacin biosynthesis, whereas others are important for optimal biosynthesis rates.
Assuntos
Substituição de Aminoácidos , Bacteriocinas/biossíntese , Sinais Direcionadores de Proteínas , Streptococcus mutans/metabolismo , Sequência de Aminoácidos , Bacteriocinas/química , Bacteriocinas/genética , Bacteriocinas/farmacologia , Genes Bacterianos , Dados de Sequência Molecular , Mutagênese Sítio-Dirigida , Precursores de Proteínas/biossíntese , Sinais Direcionadores de Proteínas/genética , Streptococcus mutans/genéticaRESUMO
The presence of a second SigH promoter in the sigA operon of Bacillus subtilis was demonstrated by use of a promoter probe plasmid, a sigH deletion mutant, primer extension studies, and in vitro transcription with E sigma H holoenzyme. Both SigH promoters were expressed at low levels even during the growth phase but were expressed at higher levels during the early stationary phase. Expression from the upstream SigH promoter allowed the expression of both dnaE and sigA genes; however, expression from the downstream SigH promoter, which was located in the ribosome-binding site of the dnaE gene, resulted only in the expression of the sigA gene, since the truncated dnaE ribosome-binding site could not be used for initiating translation. Thus, promoter switching during the early stationary phase resulted not only in expression from SigH promoters but also in differential expression of the genes in the sigA operon.
Assuntos
Bacillus subtilis/genética , Regulação Bacteriana da Expressão Gênica , Óperon , Regiões Promotoras Genéticas , Sequência de Bases , Deleção Cromossômica , Dados de Sequência Molecular , Mutação , Plasmídeos , Biossíntese de Proteínas , RNA Bacteriano/genética , Mapeamento por Restrição , Homologia de Sequência do Ácido Nucleico , Fator sigma/genética , Transcrição GênicaRESUMO
The sigA operon of Bacillus subtilis is transcribed from at least two SigA and two SigH promoters. Primer extension and promoter probe analyses have localized a fifth promoter, P5, that is active only at later sporulation stages (T3 to T5). Mutations in the genes for the sigma factors SigG, SigK, SigH, and SigE do not block transcription from P5. The expression from P5 is blocked or severely reduced in spo0A, spo0B, spo0E, and spo0K mutants.