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1.
Ann Med ; 55(2): 2261111, 2023.
Artigo em Inglês | MEDLINE | ID: mdl-37783044

RESUMO

BACKGROUND: This study aimed to evaluate the diagnostic value of a non-invasive methylation gene test in clinical colorectal tumour screening. METHOD: The quantitative methylation-specific PCR technique was used to detect faecal methylated syndecan-2 (mSDC2) in patients who received the screening of colorectal cancer (CRC).To evaluate the positive predictive value (PPV) of mSDC2 in patients with colorectal cancer, advanced adenoma (AA), and colorectal tumor (CRN) in risk factor stratification. RESULTS: The PPV of CRC, CRC + AA and CRN in male patients were 28.03%, 43.55% and 56.24%, respectively, which were higher than female patients. The positive detection rate of mSDC2 and the PPV of CRC gradually increased with age; The PPV in patients aged over 80 years was up to 78.05%, which was more significant than in younger patients with CRC. The PPV of CRC, AA and CRN were 37.10%, 11.80% and 63.37%, respectively. mSDC2 has a high detection rate of 85-100% in AA with intramucosal carcinoma alone or in combination with severe atypical hyperplasia or villous adenoma. CONCLUSION: The mSDC2 test has a higher PPV in patients with colorectal cancer and colorectal adenoma (AD), especially in high-risk groups over 50 years of age, and may help in the early diagnosis of colorectal tumours in the future.


Assuntos
Adenoma , Neoplasias Colorretais , Humanos , Masculino , Feminino , Pessoa de Meia-Idade , Idoso de 80 Anos ou mais , Metilação , Biomarcadores Tumorais/genética , Neoplasias Colorretais/diagnóstico , Neoplasias Colorretais/genética , Valor Preditivo dos Testes , Detecção Precoce de Câncer/métodos , Adenoma/diagnóstico , Adenoma/genética , Metilação de DNA , Sindecana-2/genética
2.
J Inflamm Res ; 14: 3039-3047, 2021.
Artigo em Inglês | MEDLINE | ID: mdl-34262327

RESUMO

OBJECTIVE: This study explored the correlation between myocardial infarction (MI) and the Glu504Lys polymorphism in the aldehyde dehydrogenase 2 (ALDH2) gene in the Qingyuan area. METHODS: The Glu504Lys polymorphism of the ALDH2 gene was analyzed using the polymerase chain reaction and deoxyribonucleic acid microarray analysis for 468 patients diagnosed with MI for the first time and 132 healthy subjects. RESULTS: There was a significant difference in the distribution of the ALDH2 genotype between the MI group and the control group (P = 0.0492), but there was no significant difference in allele frequency between the two groups (P = 0.1363). The clinical data showed that there were statistically significant differences (P < 0.05) in the two groups' gender and age distributions, rates of diabetes and hypertension, levels of alcohol and tobacco use, serological levels of heart markers, blood lipids and glucose. The subgroup analysis of ALDH2 genotypes found that alcohol consumption, high levels of myoglobin, and low levels of high-density lipoprotein cholesterol were significantly associated with a higher incidence of MI (P < 0.05). After adjusting for gender, hypertension, diabetes, and other related influencing factors, logistic regression analysis showed that the ALDH2 genotype GA/AA was an independent risk factor for MI (P < 0.05, OR = 1.479, 95% CI = 1.003-2.179). CONCLUSION: The presence of risk alleles with the genetic effect (ALDH2 genotype GA/AA) is an independent risk factor for MI.

3.
J Inflamm Res ; 14: 7529-7537, 2021.
Artigo em Inglês | MEDLINE | ID: mdl-35002285

RESUMO

OBJECTIVE: To establish and verify the method for detecting the immune phenotype of peripheral blood T lymphocytes by cellular immune chip technology, analyze the immune status, and discuss its clinical diagnostic value of different populations in the Qingyuan area. METHODS: First, a cellular immune chip was used to detect the number of T lymphocyte subsets CD3+, CD4+, CD8+, and CD4/CD8, followed by evaluating the accuracy and precision through a comparison with flow cytometry. After passing the performance verification, a large-scale detection was performed by a cellular immune chip in 8389 cases. Immunochip technology detects the expression of T lymphocyte subsets and analyzes the differences in cellular immune function among people with physical examination, inflammation, and cancer, as well as different cancer types and in genders. RESULTS: The cell immunochip method and flow cytometry method have the same accuracy and precision in detecting specimens, and the former is fast and simple, and is suitable for clinical use; big data analysis is expected to establish a reference range for CD3+, CD4+, and CD8+ T cell counts in Qingyuan. There are statistical differences in CD3+, CD4+, CD8+ T cell counts in physical examination, inflammation and cancer populations; there are also certain differences in CD3+, CD4+, CD8+ T cell counts and CD4/CD8 ratios between different cancer types and different diseases. CONCLUSION: The method of cell immunochip technology to detect T lymphocyte subsets is simple and practical, with accurate results and rapid detection. It can be used for immune function monitoring and treatment prognosis evaluation of people with different diseases, and it is worthy of popularization and application in clinical practice.

4.
Cardiovasc Diagn Ther ; 10(3): 520-525, 2020 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-32695631

RESUMO

BACKGROUND: Atherosclerosis is one of the most common cardiovascular and cerebrovascular diseases. This study aimed to explore the correlation between gene polymorphism of human apolipoprotein E (ApoE) and lipoprotein-associated phospholipase A2 (Lp-PLA2). METHODS: A total of 220 patients with atherosclerotic cardiovascular disease who were treated in our hospital from June 2016 to March 2017 were enrolled in this study and assigned as the atherosclerotic cardiovascular disease group and 193 patients who were treated contemporaneously in our hospital but had no atherosclerotic cardiovascular disease were enrolled and assigned as the control group. Gene polymorphism of ApoE was detected by PCR-fluorescent probe technique and the level of Lp-PLA2 was detected by ELISA. RESULTS: There were a total of 5 genotypes of ApoE in these two groups, which were E2/3, E3/3, E3/4, E2/4, and E4/4. E2/2 was not found in any of the patients. E3/3 made up the majority in both groups. There was no significant difference between the proportion of genotypes and frequencies of alleles in the two groups (P>0.05). There was no difference between LP-PLA2 among the different genotypes in these two groups (P>0.05). CONCLUSIONS: We cannot conclude that ApoE gene polymorphism is related to atherosclerotic cardiovascular and cerebrovascular diseases. And it cannot be concluded that ApoE gene polymorphism is related to Lp-PLA2 level.

5.
Artigo em Inglês | WPRIM (Pacífico Ocidental) | ID: wpr-776604

RESUMO

OBJECTIVE@#To evaluate the effect of tai chi exercise on cardiac and static lung function for older community-dwelling adults at risk of ischemic stroke.@*METHODS@#A total of 170 older community-dwelling adults (aged 55-75 years old) at risk of ischemic stroke were allocated to either tai chi training group (85 cases, five 60-min sessions of tai chi training per week for 12 weeks) or control group (85 cases, usual pbysical activity for 12 weeks) using a computer-generated randomization. The echocardiographic parameters of cardiac structure, cardiac function and static lung function were measured at baseline, after 12 weeks of intervention and additional 12-week follow-up period by a blinded professional staffmember using a color Doppler ultrasound imaging device or a cardiopulmonary function instrument. The t test and linear mixed model based on the intentionto-treat analysis principle was used to calculate the effect. The adverse effect was observed.@*RESULTS@#Most of echocardiographic parameters on the cardiac structure, cardiac function and static lung function between the tai chi group and control group did not have a significant difference either post 12-week intervention or additional 12-week follow-up period. Only three parameters involving in right ventricular diameter (P=0.024), main pulmonary artery diameter (P=0.002) and vital capacity maximum (P=0.036) were beneficial to be improved in the tai chi group compared to the control group by the analysis of mixed linear model. No adverse effects were found during the intervention period.@*CONCLUSION@#The 12-week tai chi exercise did not have an obvious beneficial effect on cardiac structure, cardiac function and static lung function in older community-dwelling adults at risk of ischemic stroke. The study with a longer duration of intervention should be necessary. (Trial registration No. ChiCTR-TRC-13003601).

6.
Oncotarget ; 8(39): 65370-65385, 2017 Sep 12.
Artigo em Inglês | MEDLINE | ID: mdl-29029437

RESUMO

Hepatocellular carcinoma (HCC) is a highly aggressive, solid malignancy that has a poor prognosis. Long non-coding RNAs (lncRNAs) have been found to be dysregulated in various cancers, including HCC. However, the molecular mechanism involving lncRNAs in HCC remains largely unknown. In this study, lncRNAs differentially expressed between HCC and corresponding non-cancerous tissue were identified by microarray analysis. A specific differentially expressed lncRNA UBE2CP3 (ubiquitin conjugating enzyme E2 C pseudogene 3) was identified. LncRNA UBE2CP3 was frequently up-regulated in HCC samples as assessed by quantitative real-time polymerase chain reaction (qRT-PCR) and in situ hybridization (ISH) experiments. Clinical data showed that high levels of lncRNA UBE2CP3 were correlated with poor prognosis in HCC patients. Functional studies demonstrated that over-expression of lncRNA UBE2CP3 promoted cell invasion and migration in vitro and in vivo. Mechanistically, enhanced expression of lncRNA UBE2CP3 increased the expression of Snail1 and N-cadherin, but decreased the expression of E-cadherin, thus promoting the process of epithelial to mesenchymal transition (EMT) and finally inducing cell invasion and migration. Furthermore, serum levels of lncRNA UBE2CP3 were increased in HCC patients and decreased after surgery. Our results suggest that lncRNA UBE2CP3 promotes the metastasis of HCC and that serum lncRNA UBE2CP3 may be a new biomarker for the diagnosis of HCC.

7.
Chinese Herbal Medicines ; (4): 167-172, 2015.
Artigo em Chinês | WPRIM (Pacífico Ocidental) | ID: wpr-842271

RESUMO

Objective: The purpose of this work is to evaluate the in vitro inhibitory effect of magnolol (MN) and honokiol (HN) on rat/human cytochrome P450 (CYP) enzymes (1A2/1A2, 2D/2D6, 3A/3A4, 2E1/2E1, and 2C/2C9). Methods: Rat liver microsomes (RLM) and human liver microsomes (HLM) were used as the enzyme sources. After the probe substrate of each CYP isoforms was co-incubated individually with MN or HN in RLM or HLM, the metabolite production of each probe substrate in RLM and HLM incubation medium was determined and used to evaluate the activity of corresponding CYP isoforms. Results: MN inhibited rat CYP1A2 and human CYP3A4 with the IC50 values of 10.0 and 56.2 μmol/L, respectively. HN inhibited rat CYP1A2 and CYP2E1, human CYP1A2 and CYP3A4 with the IC50 values of 12.1, 12.6, 17.8, and 43.9 μmol/L, respectively. Conclusion: HN is a moderate or weak inhibitor of human CYP1A2. Both MN and HN are weak or non inhibitors of the other tested human CYP isoforms. The results suggest that no significant metabolic interaction seems likely to occur when the substrate drugs of CYP isoforms tested in the present work are co-administered with MN and HN.

8.
Eur J Pediatr ; 171(7): 1073-9, 2012 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-22311167

RESUMO

The present study measures the nutritional status and the blood pressure to assess their relationship in a group of children and adolescents in the Hainan province, China. A total of 5,456 students aged 7 to 18 years were recruited from 10 public schools in Hainan province of South China during the period March 2009 to December 2009. Height, weight, systolic blood pressure, and diastolic blood pressure were measured by health-care professionals. Body mass index (BMI) was calculated and used to define thinness, overweight, and obesity according to the existing standards. Prevalence of thinness, overweight, obesity, pre-hypertension, and hypertension was computed, and logistical regression model was used to examine the association of BMI with elevated blood pressure. A high prevalence of thinness was observed in male and female children and adolescents (34.0% and 34.3%, respectively). The percentage of overweight and obesity was 2.7% and 1.3%, respectively. Pre-hypertension and hypertension were detected in 3.9% and 3.3% children and adolescents, respectively. Multivariate logistical regression analysis showed that obesity was positively associated with both pre-hypertension and hypertension, with adjusted odds ratio of 1.44 (95% confidence interval (CI) = 1.08-1.92, P = 0.014) and 2.00 (95%CI = 1.53-2.60, P < 0.001) compared to normal weight students. Overweight was also associated with pre-hypertension and hypertension. However, no significant association between thinness and pre-hypertension and hypertension was found. In conclusion, this study showed that thinness, especially mild thinness, was a major public health problem among children and adolescents in Hainan province of South China. Overweight and obesity were strongly associated with pre-hypertension and hypertension among studied students.


Assuntos
Hipertensão/etiologia , Sobrepeso/complicações , Magreza/epidemiologia , Adolescente , Determinação da Pressão Arterial , Índice de Massa Corporal , Criança , China/epidemiologia , Estudos Transversais , Feminino , Inquéritos Epidemiológicos , Humanos , Hipertensão/epidemiologia , Modelos Logísticos , Masculino , Análise Multivariada , Estado Nutricional , Obesidade/complicações , Obesidade/epidemiologia , Sobrepeso/epidemiologia , Prevalência
9.
Chinese Journal of Hepatology ; (12): 769-773, 2012.
Artigo em Chinês | WPRIM (Pacífico Ocidental) | ID: wpr-296817

RESUMO

<p><b>OBJECTIVE</b>To investigate the in vivo functional roles of the La autoantigen (La), the human homologue of the 33-kDa vesicle-associated membrane protein-associated protein (hVAP-33), and the subunit gamma of the human eukaryotic initiation factors 2B (eIF2Bgamma) as co-infection factors supporting chronic infection with hepatitis C virus (HCV).</p><p><b>METHODS</b>Small interfering (si)RNAs were designed against the HCV internal ribosome entry site (IRES) and transfected into Huh7 cells chronically infected with the HCV pseudovirus (designated as Huh7-HCV cells). The IRES siRNA producing the most effective silencing was selected for further analysis by fluorescence quantitative polymerase chain reaction (qPCR). siRNAs designed against La, hVAP-33, and eIF2Bgamma and the IRES-specific siRNA were then transfected, respectively or in various combinations, into the Huh7-HCV cell line for 48 h. The delta CT values were calculated and used to compare the HCV inhibitive efficacies of the siRNAs in isolation or in combination. Western blotting analysis was used to compare the quantity of core protein expression in each group.</p><p><b>RESULTS</b>The four gene-specific siRNAs, in isolation or in combination, caused inhibition of HCV replication and gene and protein expressions to varying degrees. The combination of La + IRES siRNAs produced the strongest inhibition of HCV core antigen expression. The combinations of hVAP-33 + IRES siRNAs and eIF2Bgamma + IRES siRNAs produced stronger inhibitions of HCV replication and gene and protein expressions than either hVAP-33 siRNA or eIF2Bgamma siRNA alone.</p><p><b>CONCLUSION</b>La, hVAP-33, and eIF2Bgamma act as co-infection factors of HCV chronic infection in vivo. HCV replication and gene and protein expression can be inhibited significantly by RNA interference of these co-infection factors and/or HCV IRES.</p>


Assuntos
Humanos , Autoantígenos , Genética , Linhagem Celular , Fator de Iniciação 2B em Eucariotos , Genética , Hepacivirus , Alergia e Imunologia , Fisiologia , RNA Interferente Pequeno , Genética , Ribonucleoproteínas , Genética , Proteínas de Transporte Vesicular , Genética , Replicação Viral
10.
Chinese Journal of Epidemiology ; (12): 509-512, 2012.
Artigo em Chinês | WPRIM (Pacífico Ocidental) | ID: wpr-288141

RESUMO

Objective To examine the impact of pregnancy termination before 28 weeks of gestation on the overall prevalence of neural tube defects (NTDs).Methods Data collected during the period of 2004 and 2010 from a birth defects surveillance system in Pingding county and Talgu county of Shanxi province were used.Number of births ≥28 weeks of gestation and number of cases with major birth defects among the births were collected.Terminations of pregnancies before 28 weeks of gestation due to prenatal diagnosis were also collected.The total prevalence of neural tube defects,prevalence before 28 weeks of gestation,and prevalenee of ≥28 weeks gestation were calculated using the total number of pregnancies of ≥28 weeks of gestation as denominator.The prevalence data were compared to examine the impact of pregnancy termination on the total prevalence.The proportions of pregnancy terminations before 28 weeks of gestation due to prenatal diagnosis of an NTD against the total number of NTD cases were also calculated.Results During 2004-2010,52 366 births were recorded,and 485 NTD cases were ascertained.The overall prevalence of NTDs was 92.6 per 10 000 births,with prevalence of <28 weeks gestation due to pregnancy terminations as 60.9 per 10 000 births,while the prevalence of ≥28 weeks of gestation was 31.7 per 10 000 births.NTD prevalence of ≥28 weeks gestation was 66.0% lower than the total NTD prevalence.In the last two years,the proportion of NTDs ascertained ≥28 weeks gestation accounted for about 40.0% of the total NTD cases.Conclusion A birth-defect-surveillance program that covered only tregnancies ≥28 weeks of gestation resulted in a severe underestimation of the total birth prevalence of NTDs,especially for anencephaly.We would recommend that the current national birth defects surveillance system should include pregnancy terminations before 28 weeks of gestation and the calculation of total NTD prevalence should also include these cases into the numerator,so as to better estimate true population NTD prevalence,upon which the related public health policy is based.

11.
Huan Jing Ke Xue ; 31(1): 88-92, 2010 Jan.
Artigo em Chinês | MEDLINE | ID: mdl-20329521

RESUMO

The method of locating online sensor on a water distribution system for monitoring water quality was investigated. A flaw of demand coverage method was identified. To overcome this flaw, a demand coverage index based method was proposed in this paper. The demand coverage index method evaluates a node's representativeness by taking both the total amount of demand coverage and its temporal distribution into account. This increases the calculation accuracy and data representativeness. In order to increase the speed of optimization, a genetic algorithm was employed to solve the optimization problem in this work. Two example water distribution systems were employed to evaluate the performances of both methods. It was obtained that more than 85% of node demand can be covered by 7 monitoring stations for the example water distribution system with 95 nodes. Example applications show that results from this method have better representativeness than the one from demand coverage method. An online monitoring network based on optimal locations obtained from demand coverage method can better represent water quality of the distribution systems.


Assuntos
Monitoramento Ambiental/métodos , Poluentes da Água/análise , Abastecimento de Água , Algoritmos , Técnicas de Apoio para a Decisão , Controle de Qualidade
12.
Artigo em Chinês | WPRIM (Pacífico Ocidental) | ID: wpr-403036

RESUMO

BACKGROUND: Streptococcus mutans (S. mutans) is generally considered to be the principal aetiological agent for dental caries, thrS gene may relate to the virulence of S. mutans involved in the adherence, acidogenicity and acidodurance.OBJECTIVE: To investigate the conservation status of the thrS gene of S. mutans and to construct the homologous recombinant plasmid.METHODS: Southern Blot was used to analyze the distdbuUon of thrS gene in S. mutans. The upstream and downstream sequences of thrS gene were cloned respectively into multiple cloning sites of suicide plasmid pFW5 to construct the recombinant plasmid,RESULTS AND CONCLUSION: The thrS gene was conserved in 6 strains of S. mutans in this test. By PCR analysis and enzyme digesting, it was confirmed that S. mutans thrS gene homologous recombinant plasmid was successfully constructed,which can be used in future research of construction of thrS -negative mutans of S. mutans strain UA159.

13.
Chinese Journal of Hepatology ; (12): 258-262, 2009.
Artigo em Chinês | WPRIM (Pacífico Ocidental) | ID: wpr-310115

RESUMO

<p><b>OBJECTIVE</b>To investigate the incidence, clinical features and prognostic implications of ischemic hepatitis in hepatitis B related liver cirrhotic patients with upper gastrointestinal hemorrhage.</p><p><b>METHODS</b>By retrospective review of the medical records of all 264 inpatients with upper gastrointestinal hemorrhage of hepatitis B related liver cirrhosis from January 1st 2007 to November 30th 2008, 11 patients with ischemic hepatitis (IH) were identified. The clinical features and prognostic implications were compared between the IH patients and 30 patients without ischemic hepatitis (control group).</p><p><b>RESULTS</b>The incidence of ischemic hepatitis was 4.17% in hepatitis B related liver cirrhotic patients with upper gastrointestinal hemorrhage. The patients in IH group were younger than those in control group, the average age was (43.1+/-5.7) in IH group and (52.3+/-11.1) in control group (P=0.013). The serum alanine aminotransferase and aspartate aminotransferase were increased more than 20-fold above the upper limit of normal values, and returned to normal values within 10 days. Compared to the control group, total bilirubin, lactate dehydrogenase, alkaline phosphates, gamma-glutamyltransferase, blood urea nitrogen, creatinine, and white blood cells were increased, while serum cholinesterase was decreased in IH group (P<0.05). The fatality rate of ischemic hepatitis was much higher than that of control group (54.5% vs 16.7%, P=0.041). The main causes of death in IH group were infection, hepatorenal syndrome and hepatic encephalopathy. The patients in IH group lost 200 to 3600 milliliter blood, and hemorrhagic shock occurred in 63.6% (7/11) of IH patients. Therefore the bleeding volume was not correlated with the occurrence rate of ischemic hepatitis.</p><p><b>CONCLUSION</b>Ischemic hepatitis may occur secondary to upper gastrointestinal hemorrhage in hepatitis B related liver cirrhosis. The risk factors of ischemic hepatitis in cirrhositic patients with upper gastrointestinal hemorrhage are young and with hemorrhagic shock, and poor liver function. It is important to use antibiotics in time to improve the prognosis of these patients.</p>


Assuntos
Adulto , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Alanina Transaminase , Sangue , Aspartato Aminotransferases , Sangue , Biomarcadores , Sangue , Hemorragia Gastrointestinal , Hepatite , Epidemiologia , Patologia , Hepatite B , Isquemia , Epidemiologia , Patologia , Fígado , Cirrose Hepática , Prognóstico , Estudos Retrospectivos , Fatores de Risco
14.
National Journal of Andrology ; (12): 43-49, 2006.
Artigo em Chinês | WPRIM (Pacífico Ocidental) | ID: wpr-338371

RESUMO

<p><b>OBJECTIVE</b>To set up a method of establishing the animal model of psychical erectile dysfunction with emotional stress.</p><p><b>METHODS</b>All thirty-six male rats with normal sexual function were divided into three groups, i. e. normal group, model group and demasculinized group randomly according to their weights. The rats in the model group were suspended upside down in midair over the water and irritated repeatedly. Two weeks later, the sexual abilities of all rats, i. e. the times of mounting and intromitting the estrus female rats, the latent period of mounting, intromission and ejaculation, were recorded, and the number of rats that had sexual activities was also counted. And the hemorheology indices of the rats were measured.</p><p><b>RESULTS</b>Compared with the normal rats, the latency of mounting [(152.5 +/- 24.6) s vs (42.4 +/- 9.6) s] and intromission [(437.0 +/- 67.7) s vs (130.8 +/- 39.1) s] of the model rats were longer (P < 0.01), but the latency of ejaculation [(385.3 +/- 80.0) s vs (547.3 +/- 69.4) s] was shorter (P < 0.05) than that of the normal. There was no significant difference in the times of mounting between normal [(38.3 +/- 6.1) vices and model rats (38.5 +/- 5.4) vices], but the intromission times of model rats [(9.2 +/- 1.7) vices] was lower than that of the normal rats [(20.3 +/- 3.1) vices], P < 0.01. Compared with the normal rats, the sexual activity incidence of the model rats (mounting: 58.3%, intromission: 33.3%, ejaculation: 16.7%) was significant lower than that of the normal rats (100%) (P < 0.01). But there was no significant difference in the sexual ability between the model and the demasculinized rats (P > 0.05). The hemorheology indices, e. g. blood viscosity, hematocrit (Hct) and red cell aggregation (RCA), of the model rats was significant higher than that of the normal and demasculinized rats (P < 0.05), but there was no significant difference between the normal and demasculinized rats.</p><p><b>CONCLUSION</b>The rat model of psychical erectile dysfunction can be made ideally with psychical stress.</p>


Assuntos
Animais , Feminino , Masculino , Ratos , Comportamento Animal , Modelos Animais de Doenças , Disfunção Erétil , Psicologia , Hemorreologia , Humor Irritável , Distribuição Aleatória , Ratos Sprague-Dawley
15.
Artigo em Chinês | WPRIM (Pacífico Ocidental) | ID: wpr-545905

RESUMO

Objective:To knock the phospho-sugar mutase gene (psm) out of the genome of S. mutans strain UA159 and to construct the mutant will lay a foundation for the study of the function of the psm. Methods:Two upstream and downstream DNA sequences of the psm were selected and cloned respectively into multiple cloning sites I and II of suicide plasmid pFW5 to construct the recombinant plasmid which was confirmed by enzyme digesting and sequencing. The recombinant plasmid was transformed into S. mutans UA159 by natural transformation and antibiotic was used to screen the positive transformants. According to the principle of homologous recombination, allelic exchange between the recombinant plasmid and S. mutans UA159 was achieved. Results:By PCR analysis and sequencing, it was confirmed that the psm of S. mutans UA159 was substituted for resistant gene of spectinomycin. Conclusion: The psm-negative mutants of S. mutans UA159 is successfully constructed.

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