Prenatal diagnosis of β-thalassaemia using cell-free fetal DNA in maternal plasma / 南方医科大学学报

<p><b>OBJECTIVE</b>To investigate the clinical feasibility of cell-free fetal DNA (cffDNA)-based noninvasive prenatal diagnosis of β-thalassemia.</p><p><b>METHODS</b>Nine samples of amniotic fluid were obtained to detect the 8 common and 9 relatively rare mutation sites of β-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 β-globin genotype was analyzed by reverse dot-blot hybridization.</p><p><b>RESULTS</b>Among the 9 cases, 5 showed fetal genotypes of β-thalassemia inherited from the father by examination of the amniotic fluid, and 2 fetuses were identified to have β-thalassemia genes inherited from the father determined based on the cffDNA in the maternal blood.</p><p><b>CONCLUSIONS</b>The cffDNA-based noninvasive prenatal diagnosis is feasible for β-thalassemia, but the contamination of the maternal background DNA results in a low detection rate.</p>

Rapid detection of oxacillin and erythromycin resistance genes in Staphylococcus aureus using multiplex PCR / 南方医科大学学报

<p><b>OBJECTIVE</b>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.</p><p><b>METHODS</b>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.</p><p><b>RESULTS</b>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.</p><p><b>CONCLUSION</b>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.</p>

Induced differentiation and signaling factor PTEN expression of 3T3-L1 adipocytes / 南方医科大学学报

<p><b>OBJECTIVE</b>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.</p><p><b>METHODS</b>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.</p><p><b>RESULTS</b>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.</p><p><b>CONCLUSION</b>Endogenous PTEN expression is down-regulated during 3T3-L1 differentiation, suggesting that PTEN may enhance insulin sensitivity and promote adipogenesis under physiological conditions.</p>

Repetitive element-based polymerase chain reaction to track the nosocomial infec- tions caused by Staphylococcus aureus / 中国感染与化疗杂志

Objective The technique of repetitive element-based polymerase chain reaction(rep-PCR)was used to track an epi- demic of nosocomial infection caused by Staphylococcus aureus in our hospital.Methods The 50 S.aureus isolates were identi fled by PHOENIX-100 automatic Microbiological Identification System.Oxacillin-salt-supplemented agar was used to screen methicillin-resistant S.aureus(MRSA)phenotype.The resistant gene mecA was tested by PCR.The technique of rep-PCR was applied to type S.aureus isolates.Results The mecA gene was identified in 22 of the 50 S.aureus isolates.Nineteen of the 22 strains were isolated from patients.Nine to eleven bands were observed in electrophoretic pattern of all the 50 S.aureus iso- lates by rep-PCR under the conditions of this study.These strains were accordingly classified into 11 different genotypes.Con- clusions The rep-PCR technique is a rapid,simple and reliable genotyping method.It is an ideal tool to track the source of noso- comial infections at molecular level.

Hemoglobin H disease combining hemoglobin Q-thailand and hemoglobin E disease:a clinical and laboratory genealogical research / 中华检验医学杂志

Objective To investigate clinically and in laboratory a genealogical tree with hemoglobin H disease Combining Hemoglobin Q-Thailand and Hemoglobin E Disease.Methods Genealogical laboratory studies were carried out with the following methods:hemoglobin electrophoresis, various biochemical determinations,and DNA analysis.Results Father's genotype of ?-THAL:??/?~Q ?~(4.2); genotype of ?-THAL:?E/N;phenotype:minor ?-THAL carrier combining Hb Q and Hb E multiple heterozygote;mother' s genotype of ct-THAL:--~(SEA)/??;genotype of ?-THAL:?n/?n.According to comprehensive analysis,mother's phenotype:minor ?-THAL,complex minor ?-THAL carrier combining Hb F ? Initial sign of ?-THAL genotype:--~(SEA)/?~Q ?~(4.2);phenotype:deletion type Hb H genotype disease;?- THAL genotype:?E/?E;phenotype:? E homozygote.According to comprehensive analysis:deletion type Hb H combining HbE multiple heterozygote.Youger brother's ?-THAL genotype:--~(SEA)/?~Q ?~(4.2);?-THAL genotype:?n/?n;phenotype:deletion type Hb H disease.Both mother and her youngest son have G6PD deficiency.Conclusions Guangdong Province is an area with high morbidity of ?-THAL and ?-THAL,Hb E and Hb Q as well as G6PD deficiency.There may be some correlation between Hb E and Fib Q in term's of the high morbidity of regional Hb,but the two types of Hb combining Hb H disease are rare in China and the world in point of nonhomologous chromosome.Attention should be paid to the problems of double heterozygote of ?-THAL complex ?-THAL,and THAL complex G6PD deficiency.Data from the study have enriched the scientific information of molecular genetics of erythroeyte thalassemia and of molecular pathology with important significance in genetics guidance and clinical treatment for patients.