Bai Xiao

Capital Medical University, Peping, Beijing, China

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Publications (48)43.16 Total impact

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    ABSTRACT: Streptococcus mutans (S. mutans) is the prime pathogen of dental caries. There are few reports that studied the relationship between S. mutans, bacteria and dental caries in permanent teeth when compared to those in primary teeth. This study aimed to detect S. mutans and bacteria of dental caries and non-caries groups in permanent teeth from a north China population by real-time polymerase chain reaction (PCR) and compare the relationship between the number of these bacteria and the prevalence of dental caries in permanent teeth. Human saliva samples were collected from 142 subjects with permanent teeth. According to their dental tooth (DT), 142 subjects were divided into a dental caries group (DT ≥ 1) and a non-caries group (DT = 0). With specific primers for S. mutans and 16S rRNA, the total number of S. mutans and total bacteria of 142 saliva samples were detected by real-time PCR and statistically analyzed. There was no significant difference between the detection rates of S. mutans (P = 0.118) and medians of S. mutans (P = 0.115). The ratio of S. mutans to total bacteria in people with dental caries was significantly higher than in those without caries (P < 0.001), but the total number of bacteria in people with dental caries was significantly lower than in those without caries (P < 0.001). S. mutans had different effects on caries in the permanent teeth of several individuals from a north China population. The ratios of S. mutans to total bacteria in saliva detected by real-time PCR with Sm479F/R and 16S RNA primers were closely associated with the prevalence of dental caries in the same population. These assays may be useful for the assessment of an individual's risk of dental caries.
    Chinese medical journal 11/2012; 125(21):3880-4. · 0.90 Impact Factor
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    ABSTRACT: To establish a comprehensive and simple assay using denaturing high performance liquid chromatography (DHPLC) for the diagnosis of most common mutations and deletions of α-thalassemia gene in Southeast Asians and Southern Chinese. This assay has included a duplex polymerase chain reaction (PCR) followed by DHPLC analysis. An improved PCR was also performed followed by DHPLC analysis. With this assay, a blinded study of 160 samples was screened for three common mutations and three common deletions. The duplex PCR-DHPLC combined with the improved PCR-DHPLC analysis has detected all mutations and the wild-type allele. The results were consistent with those by the original methods. This molecular assay may be used for the diagnosis of α-thalassemia patients from this geographical region. The method is accurate, rapid, semi-automatic and cost-effective, which makes it suitable for large-scale screening.
    Zhonghua yi xue yi chuan xue za zhi = Zhonghua yixue yichuanxue zazhi = Chinese journal of medical genetics 12/2011; 28(6):670-4.
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    ABSTRACT: Multiplex ligation-dependent probe amplification (MLPA) has been used to detect deletions and mutations of the α-globin gene for diagnosis of α-thalassemia. MLPA reaction products are usually separated and analyzed by high-voltage capillary gel electrophoresis (CGE). The goal of this study was to find and use a cost-effective method to separate and analyze MLPA products. Blood samples were collected from China. DNA was extracted and amplified by PCR using fluorescently labeled primers. In this study, denaturing high-performance liquid chromatography (DHPLC) was used to separate and analyze the reaction products. And the optimal separation conditions were determined using nondenaturing columntemperature. The DHPLC conditions were optimized and have been applied to separate MLPA products and 27 of the MLPA products from 50 to 320 bp were well separated. DHPLC was able to separate up to 37 reaction products that differed by 4-12 base pairs and detected target gene deletions by differences in peak size. Compared with CGE, both the specificity and sensitivity of DHPLC for the 107 DNA samples were 100%. DHPLC could be used to test routinely for α-globin gene mutations and deletions. Combined with MLPA, DHPLC is a low-cost, simple to use, accurate technique with practical value.
    Journal of Clinical Laboratory Analysis 11/2011; 25(6):426-31. · 1.36 Impact Factor
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    ABSTRACT: To detect the gene mutations of beta-myosin heavy chain gene (MYH7) in Chinese pedigrees with hypertrophic cardiomyopathy (HCM), and to analyze the correlation between the genotype and phenotype. Exons 3, 5, 7-9, 11-16 and 18-23 of the MYH7 gene were amplified with PCR in three Chinese pedigrees with HCM. The products were sequenced. Sequence alignment between the detected and the standard sequences was performed. A missense mutation of Thr441Met in exon 14 was identified in a pedigree, which was not detected in the controls. Several synonymous mutations of MYH7 gene were detected in the three pedigrees. The mutation of Thr441Met, located in the actin binding domain of the globular head, was first identified in Chinese. It probably caused HCM. HCM is a heterogeneous disease. Many factors are involved in the process of its occurrence and development.
    Zhonghua yi xue yi chuan xue za zhi = Zhonghua yixue yichuanxue zazhi = Chinese journal of medical genetics 08/2011; 28(4):387-92.
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    ABSTRACT: Deletion mutations of 3.7 kb and 4.2 kb of α-globin gene are the most common causes of α-thalassemia (-α(3.7)/, -α(4.2)/). A simple, rapid assay by using a single-tube PCR to detect the two deletions has been needed. In this study, a pair of shared primers was designed for α2 and α1 gene but with length-different amplicons (159 bp and 409 bp). On the dissociation curve analysis profile after PCR, there shows two obvious peaks which represent the two different amplicons. Relative copy number of α2 and α1 gene can be deduced from the ratio of the two peaks. A comprehensive diagnosis for α-thalassemia 10 genotypes of deletions can be achieved when combined with a single-tube duplex PCR for detecting --SEA and non-deletional alleles of αα or α(T)α. Besides, a single-tube multiplex PCR, which is a cost-effective version of dual-priming-oligonucleotide based system, was designed for two common mutations of α-thalassemia in China (Hb Constant Spring and Hb Quong Sze), and these two mutations can be identified in samples by use of dissociation curve analysis. In all, using above three PCRs followed by dissociation curve analysis, three deletions and two mutations of α-thalassemia in the populations of southern China and Southeast Asia can be detected for molecular diagnosis or prenatal diagnosis. A blinded study of 163 samples was performed using this new assay and it was concordant with the original methods. This comprehensive molecular assay is simple, rapid, automatic and cost-effective, and can be used to diagnose α-thalassemia in this geographical area.
    Experimental and Molecular Pathology 07/2011; 91(2):626-30. · 2.13 Impact Factor
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    ABSTRACT: To investigate the application value of the multiplex ligation-dependent probe amplification (MLPA) technique in diagnosis and prenatal diagnosis of chromosomes 13, 18, 21, X and Y aneuploidy. Forty-four cases including 30 peripheral blood samples, 10 fetal cord blood samples, and 4 amniotic fluid samples were collected in this study. DNA was isolated from the samples and detected by MLPA, followed by analyzing in ABI310 Genetic Analyzer. Analysis of copy number changes for chromosomes 13, 18, 21, X and Y was carried out with RH-MLPA-analysis software. The routine karyotype analyses were also done for all the samples. Of 44 samples, the results of 42 by MLPA method was consistent with that by chromosome karyotyping. Only one case with trisomy 21 chimerism was failed to reach conclusion. In addition, one case of mark chromosome segment was identified as Y-chromosome segment by MLPA, while karyotyping failed to make judgment. The accurate rate of MLPA was 97.7% (43/44). The MLPA technique can simultaneously detect dozens of different target sequences and their copy number changes in a single reaction. It showed high specificity, good reproducibility, was fast and high-throughput. The MLPA technique can be applied to diagnosis and prenatal diagnosis of the common chromosomal aneuploidy.
    Zhonghua yi xue yi chuan xue za zhi = Zhonghua yixue yichuanxue zazhi = Chinese journal of medical genetics 04/2011; 28(2):212-6.
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    ABSTRACT: To improve the experimental method of DXS52 (St14) and apply it to genetic testing for hemophilia A (HA). PCR of DXS52 and agarose gel electrophoresis were performed for genetic testing in 61 non-inversion HA families. Linkage analysis of 7 loci within the FVIII gene including Bcl I, Hind III, Xba I, STR1, STR13, STR22 and STR24 were also carried out for the 61 families. DXS52 can provide information in 43 out of 61 families and the diagnostic rate was 70.5%. Eight families can be diagnosed only by DXS52 locus, accounting for 13.1%. Two families were found to have recombination between DXS52 and FVIII. The new experimental conditions can reach accurate and clear results in DXS52 genetic testing. This gene maker has high diagnostic rate, so it is an indispensable linkage analysis method in HA gene diagnosis. More caution should be paid when using the extragenic locus DXS52 to perform gene diagnosis because of its high recombinant rate with FVIII.
    Zhonghua yi xue yi chuan xue za zhi = Zhonghua yixue yichuanxue zazhi = Chinese journal of medical genetics 02/2011; 28(1):19-22.
  • American Journal of Hematology 05/2010; 85(5):370-2. · 4.00 Impact Factor
  • Annals of Hematology 05/2010; 90(1):125-6. · 2.87 Impact Factor
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    ABSTRACT: To establish a quantity detection method of Streptococcus mutans (Sm) and bacteria and compare the relationship between the number of these bacteria and the prevalence of dental caries in different people. With specific primers for a unique sequence in a 14 kb HaeIII restriction fragment consistently presenting during detecting Sm by chromosomal DNA fingerprints, the total number of Sm and bacteria of 99 saliva samples were detected by real-time polymerase chain reaction (PCR) and statistically analyzed. The primers were specific for Sm and the minimum detectable level by real-time PCR was 0.1 microg/L. The total number of bacteria in the dental caries and people without caries was 51.4 x 10(8) cell copies/L and 221.6 x 10(8) cell copies/L respectively, in which the ratio of Sm to bacteria was 0.0193 and 0.0059 respectively. The differences were significantly different between the people with dental caries and those without caries in the total number of bacteria and the ratio of Sm to bacteria. The primers can be used to detect the Sm by real-time PCR. The ratio of Sm to bacteria was closely associated with the prevalence of dental caries.
    Zhonghua kou qiang yi xue za zhi = Zhonghua kouqiang yixue zazhi = Chinese journal of stomatology 04/2010; 45(4):223-7.
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    ABSTRACT: Populations in Southeast Asia and South China have high frequencies of alpha-thalassemia caused by alpha-globin gene mutations and/or deletions. This study was designed to find an efficient and simple diagnostic test for the mutations and deletions. A duplex polymerase chain reaction (PCR)/denaturing high-pressure liquid chromatography (DHPLC) was used to detect the mutations and deletions. A blinded study of 110 samples, which included 92 alpha-thalassemia samples with various genotypes and 18 normal DNA samples, was carried out by the methods. The duplex PCR products of the sample with known Constand spring mutation (CS)/alphaalpha, Quonsze mutation (QS)/alphaalpha, and Weastmead mutation (WS)/alphaalpha DNA showed significantly different profiles, which suggests that DHPLC analysis at 63.8 degrees C can detect potential mutations directly. The DHPLC at 50 degrees C analysis can distinguish the --SEA and nondeletional alleles. The new assay is 100% concordant with the original genotype. In conclusion, the technique including the duplex PCR assay followed by DHPLC analysis can be used to diagnose alpha-thalassemia; this methodology is simple, rapid, accurate, semiautomatic, and high output, and thus, it is suitable for large-scale screening.
    Translational research : the journal of laboratory and clinical medicine. 03/2010; 155(3):148-55.
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    ABSTRACT: Hemophilia A (HA) is an X-linked inherited bleeding disorder caused by decreased activity of factor VIII (FVIII) due to heterogenous mutations in the FVIII coding gene (F8). The type of mutation plays an important role in the FVIII inhibitor formation. To date, several studies on the spectra of F8 defects have been performed in Western populations, but similar studies in Asian races are scarce. Here, we reported the distribution of the F8 gene mutations in 18 unrelated Chinese patients with HA. Intron 22 and intron 1 inversions in the F8 gene were screened in 158 unrelated patients with HA using a long-distance PCR and multiplex PCR method. Direct sequencing of the coding region of the F8 gene was used to identify the mutations responsible for HA in 18 unrelated Chinese HA patients who were negative for intron 22 and intron 1 inversions; sequences were compared with the HAMSTeRS database. A clotting method was used to assay the FVIII activity level and the Bethesda assay was used to detect the FVIII inhibitor. A total of 18 different HA F8 mutations were identified, seven of which were described for the first time. These novel mutations included five small deletions, one point mutation and one small insertion. One novel mutation (4382-3 AC deletion) was associated with inhibitor development. These data extend our insight into the mechanisms by which novel amino acid mutations may lead to HA and how the HA patient genotypes influence the risk of FVIII inhibitor.
    Chinese medical journal 02/2010; 123(3):305-10. · 0.90 Impact Factor
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    ABSTRACT: The prevailing cause of alpha-thalassemia in Southeast Asia is the presence of 3 deletion mutations in the alpha-globin genes (-SEA, -alpha(3.7) and -alpha(4.2)). Current detection methods include gap polymerase chain reaction (PCR), multiplex PCR and real-time PCR with SYBR Green 1 combined with dissociation curve analysis. To improve and simplify a previously published method that requires 4 separate reactions, a duplex PCR assay was designed to detect both the nondeletional and the -SEA alleles. This duplex PCR can successfully identify the nondeletional allele and both the -SEA carrier and homozygous genotypes. The combination of the duplex PCR and 2 gap PCRs (for detection of -alpha(3.7) and -alpha(4.2)) can diagnose all types of deletional alpha-thalassemia. Our method was validated by analysis of 195 DNA samples, the results of which were consistent with prior diagnoses. The developed assay can reliably diagnose alpha0-thalassemia and all types of deletional alpha-thalassemia. The diagnostic method is simple, rapid, accurate, automated, inexpensive and has a high throughput.
    Acta Haematologica 09/2009; 122(1):17-22. · 0.89 Impact Factor
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    ABSTRACT: Screening the intron 1 inversion of factor VIII (FVIII) in the population of severe haemophilia A(HA) in China and performing carrier detection and prenatal diagnosis. Using LD-PCR to detect intron 22 inversions and multiple-PCR within two tubes to intron 1 inversions in severe HA patients. Carrier detection and prenatal diagnosis were performed in affected families. Linkage analysis and DNA sequencing were used to verify these tests. One hundred and eighteen patients were seven diagnosed as intron 22 inversions and 7 were intron 1 inversions out of 247 severe HA patients. The prevalence of the intron 1 inversion in Chinese severe haemophilia A patients was 2.8% (7/247). Six women from family A and 2 from family B were diagnosed as carriers. One fetus from family A was affected fetus. Intron 1 inversion could be detected directly by multiple-PCR within two tubes. This method made the strategy more perfective in carrier and prenatal diagnosis of haemophilia A.
    Zhonghua yi xue yi chuan xue za zhi = Zhonghua yixue yichuanxue zazhi = Chinese journal of medical genetics 07/2009; 26(3):323-5.
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    ABSTRACT: To develop a one-tube fluorescent multiplexed polymerase chain reaction (PCR) method to perform prenatal diagnosis of haemophilia A (HA). Peripheral blood samples were collected from 220 women and from members of five families with proven HA. One-tube fluorescent PCR and capillary electrophoresis were performed to investigate four short tandem repeats (STRs) in intron 1, 13, 22 and 24 (STR1, STR13, STR22 and STR24, respectively) in FVIII. Our analysis revealed 7 different alleles for STR1, 10 for STR13, 7 for STR22 and 9 for STR24. The heterozygosity rate (HR) for STR1, 13, 22 and 24 was 34.6%, 49.6%, 43.6% and 38.2%, respectively. The HR was 75.0% (165/220) when these four markers were combined. Prenatal diagnosis was made for five male foetuses. Four foetuses were identified as affected ones of HA. The STR results were consistent with the data we obtained by PCR of St14 VNTR (DXS52) and DNA sequencing, which showed that one foetus harbours a mutation in exon12 (1804C > T) in FVIII. This study demonstrates that multiplex fluorescent analysis of four STRs is a rapid and simple method to perform genetic diagnosis of HA in families with a history of this disorder.
    Prenatal Diagnosis 04/2009; 29(7):664-7. · 2.68 Impact Factor
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    ABSTRACT: Dear Sir, A single tube polymerase chain reaction (PCR) with three primers and SYBR GREEN1 combined with dissociation curve analysis was set up that can clearly differentiate between Hb Bart's hydrops fetalis, normal subjects and - -(SEA) heterozygotes. This method seems to be simpler than that using a two-tube real-time SYBR-PCR with two different primer sets followed by analyses of DeltaC(T) and C(T) ratio.
    Hemoglobin 01/2009; 33(6):546-9. · 0.89 Impact Factor
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    ABSTRACT: To investigate the frequency of intron 1 inversion (inv1) in FVIII gene in Chinese hemophilia A (HA) patients and to investigate the mechanism of pathogenesis. Peripheral blood samples were collected from 158 unrelated HA patients, aged 20 (1 - 73), including one female HA patient, aged 5, and several family members of a patient positive in inv1. One-stage method was used to assay the FVIII activity (FVIII:C). Long distance PCR and multiple PCR in duplex reactions were used to screen for the intron 22 inversion (inv22) and inv1 of the FVIII coding gene (F8). The F8 coding sequence was amplified with PCR and sequenced with an automatic sequencer. Two unrelated patients (pedigrees) were detected as inv1 positive with a positive rate of 1.26%. A rare female HA patient with inv1 was also discovered in a positive family (3 HA cases were found in this family and regarded as one case in calculating the total detection rate). The full length of FVIII was sequenced, and no other mutation was detected. There frequency of FVIII inv1 is low in Chinese HA patients compared with other populations. Female HA patients are heterozygous for FVIII inv1 and that may be resulted from nonrandom inactivation of X chromosome.
    Zhonghua yi xue za zhi 11/2008; 88(38):2672-4.
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    ABSTRACT: To study the prenatal genetic diagnostic methods for hemophilia A fetus. From 2002 to 2006, 19 hemophilia A families were diagnosed either by long distance-polymerase chain reaction (LD-PCR) for factor VIII intron 22 inversion or by the DNA polymorphism genetic linkage analysis of factor VIII in the Beijing Chaoyang Hospital. (1) Totally 19 women, with 22 pregnancies received the prenatal diagnosis of fetal hemophilia A. The average week at diagnosis was 23 (17-34 ) weeks. All the direct fetal blood sampling (DFBS) were successful. There was no fetal-loss caused by the procedures. (2) Of the 19 hemophilia A families, 14 appeared to be factor VIII intron 22 inversion, in which 16 prenatal diagnoses were done, 10 fetuses were diagnosed as genetical hemophilia A patients, and 6 fetuses were normal. (3) Using combined polymorphism genetic linkage analysis 6 prenatal diagnoses were done, including one woman's two pregnancies, in which both her fetuses were diagnosed as genetical hemophilia A patients. (4) Factor VIII levels of 16 fetuses were measured, and 6 fetuses were unmeasured either because the pregnancy weeks were lower than 20 weeks or the parents refused. Factor VIII level ranged from 0 to 198%. There were 11 fetuses whose factor VIII levels were lower than 10%. Ten of them were diagnosed to be genetical hemophilia A patients, and in only one boy the factor VIII level was 2%, but the genetic diagnosis was normal and for one year's follow up he was doing normal. LD-PCR combined with polymorphism genetic linkage analysis enables a quick and correct detection of hemophilia A carrier. For a carrier pregnancy, prenatal diagnosis could be done for the male fetus. Factor VIII deficiency of the fetus could help make the diagnosis but the final diagnosis should be based on genetic evidence.
    Zhonghua fu chan ke za zhi 05/2008; 43(4):262-5.
  • Prenatal Diagnosis 03/2008; 28(2):160-1. · 2.68 Impact Factor
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    ABSTRACT: Molecular analysis of two fetuses at high risk of alpha-thalassemia (alpha-thal), and their family members, was performed using real-time polymerase chain reaction (PCR) with SYBR Green 1 (SYBR-PCR) dye combined with dissociation curve analysis and multiplex PCR (m-PCR) and DNA sequencing techniques. The genotype of the fetus from one family was --SEA/--SEA (Southeast Asian deletion), which produces hydrops fetalis syndrome. The genotype of the parents was --SEA/alphaalpha. A boy with Hb H disease and his sibling fetus from the other family had the genotype --SEA/alphaCSalpha [the Hb Constant Spring (CS) mutation: alpha142, Term-->Gln (TAA>CAA in alpha2)] and alphaalpha/alphaalpha (normal), respectively. The diagnosis, based on SYBR-PCR combined with dissociation curve analysis, was in agreement with the results from the m-PCR method. This indicates that these are alternative and reliable assays for the molecular diagnosis of deletional alpha-thal.
    Hemoglobin 02/2008; 32(6):553-60. · 0.89 Impact Factor