Molecular characterization of a Chinese pedigree with beta-thalassemia intermedia.

Hereditary persistence of fetal hemoglobin (HPFH), often associated with mutations in the beta-globin gene cluster, is normally benign, but a person carrying both HPFH and another beta-thalassemia (beta-thal) mutation will develop serious anemia. These people might be erroneously diagnosed as having homozygous beta-thal with common reverse dot-blot methods. Here we report a 5-year old boy with thalassemia intermedia, who is a compound heterozygote for the rare HPFH-6 deletion with codons 41/42 (-TCTT) beta(0)-thal, who inherited the deletion from his mother and the beta(41/42) mutation from his father.

[Prenatal diagnosis of ß-thalassaemia using cell-free fetal DNA in maternal plasma].

OBJECTIVE: To investigate the clinical feasibility of cell-free fetal DNA (cffDNA)-based noninvasive prenatal diagnosis of ß-thalassemia. METHODS: Nine samples of amniotic fluid were obtained to detect the 8 common and 9 relatively rare mutation sites of ß-thalassaemia in Guangdong Province. The maternal blood samples were also collected for extracting and purification of the cffDNA, and a duplex PCR was performed using 3 pairs of primers and the fetal ß-globin genotype was analyzed by reverse dot-blot hybridization. RESULTS: Among the 9 cases, 5 showed fetal genotypes of ß-thalassemia inherited from the father by examination of the amniotic fluid, and 2 fetuses were identified to have ß-thalassemia genes inherited from the father determined based on the cffDNA in the maternal blood. CONCLUSIONS: The cffDNA-based noninvasive prenatal diagnosis is feasible for ß-thalassemia, but the contamination of the maternal background DNA results in a low detection rate.

[Rapid detection of oxacillin and erythromycin resistance genes in Staphylococcus aureus using multiplex PCR].

OBJECTIVE: To establish a rapid multiplex PCR (MPCR) detection system of oxacillin and erythromycin resistance genes in Staphylococcus aureus (S. aureus) and evaluate the genotype distribution of the genes associated to mecA, ermA and ermC resistance in Guangzhou. METHODS: The S. aureus strains were identified and susceptibility tests were performed using VITEK-60 or PHOENIX-100 system. The inducible resistance to clindamycin of strains with of erythromycin resistance was conducted using D-test, and the MPCR system of for detecting the antibiotic resistance genes was optimized. RESULTS: The MPCR assay for detecting the resistance genes was constructed successfully. According to the results of MPCR, the positivity rates for mecA, ermA and ermC genes among the 124 strains of S. aureus isolated from clinical samples were 56.5%, 50% and 33.9%, respectively. Good correlation was observed between the antibiotic resistance phenotypes and the S. aureus genotypes. mecA were detected in all the methicillin-resistant S. aureus strains, and ermA and/or ermC in 97.7% of the S. aureus strains with erythromycin resistance. CONCLUSION: This MPCR system allows rapid and reliable analysis of antibiotic resistance genotypes of S. aureus isolated from clinical samples. mecA, ermA, and ermC genes are among the predominant genetic determinants for the resistance to oxacillin and erythromycin in S. aureus isolates in Guangzhou.

[Induced differentiation and signaling factor PTEN expression of 3T3-L1 adipocytes].

OBJECTIVE: To optimize the condition for inducing the differentiation of 3T3-L1 preadipocytes into adipocytes and study the expression of PTEN tumor suppression gene in this process, aiming to understand the regulatory role of PTEN in normal adipocyte differentiation and collect laboratory evidence for developing drugs targeting PTEN. METHODS: The differentiation of 3T3-L1 preadipocytes cultured in high-glucose DMEM were induced according to 2 protocols with different combinations of dexamethasone, isobutylmethylxanthine (IBMX) and insulin, and the resultant adipocytes were identified by oil red O staining. The total proteins of 3T3-L1 were extracted and analyzed by Western blotting, and PTEN homology between mice and human was analyzed by bioinformatic method. RESULTS: For optimized 3T3-L1 differentiation, 3T3-L1 cells were initially induced with the combination of 1 micromol/L dexamethasone, 0.5 mmol/L IBMX and 5 microg/ml insulin for 48 h, followed by treatment with 5 microg/ml insulin in 4.5 g/L glucose DMEM for 48 h, which resulted in high differentiation rate of 3T3-L1 cells (up to 90% on the 10th day) with unified morphology and size. PTEN expression varied quantitatively in the process of differentiation, especially low on the 12th day as compared with those measured on days 4, 6 and 9. The mice PTEN mRNA shared 96% homology and PTEN amino acid 100% homology with their human counterparts. CONCLUSION: Endogenous PTEN expression is down-regulated during 3T3-L1 differentiation, suggesting that PTEN may enhance insulin sensitivity and promote adipogenesis under physiological conditions.