pncA Mutations in the Specimens from Extrapulmonary Tuberculosis / 결핵및호흡기질환

BACKGROUND: Pyrazinamide (PZA) is an effective antitubercular drug that becomes toxic to Mycobacterium tuberculosis when converted to pyrazinoic acid by pyrazinamidase (PZase), encoded by mycobacterial pncA. A strong association was noted between the loss of PZase activity and PZA resistance. The causative organisms in extrapulmonary tuberculosis are rarely cultured and isolated. To detect pncA mutations in specimens from extrapulmonary tuberculosis as confirmative diagnosis of mycobacterial infection and alternative susceptibility test to PZA. METHODS: Specimens were collected from clinically proven extrapulmonary tuberculosis. pncA was sequenced and compared with wild-type pncA. RESULTS: pncA from 30 specimens from 23 donors were successfully amplified (56.6% in specimens, 59% in donors). Six mutations in pncA were detected (20.0% in amplified specimens, 26.1% in specimen donors) at nucleotide positions of 169, 248 and 419. The mutation at position 169 results in substitution of aspartic acid for histidine, a possible allelic variation of M. bovis that have intrinsic PZA resistance. The mutation at position 248 changes proline into arginine and that at position 419, arginine into histidine. CONCLUSION: DNA-based diagnosis using pncA may be simultaneously useful for the early diagnosis of mycobacterial infection and the rapid susceptibility to PZA in extrapulmonary tuberculosis. A potential implication of pncA allelic variation at 169 might be suggested as a rapid diagnostic test for M. bovis infection or Bacille Calmette-Guerin (BCG) reactivation.

Relationship between changes of endogenous nitric oxide synthase inhibitor and hydrolase and initiation of pre-eclampsia / 中华妇产科杂志

Objective To investigate the role of dimethylarginine dimethylaminohydrolase-2 (DDAH-2)/asymmetric dimethylarginine(ADMA)in pathophiology of preeclampsia by detecting expression of DDAH-2 in placenta and serum plasma ADMA.Methods From Jan.2004 to Jan.2005,30 preeclampsia patients(PE group)were chosen in the Third Affiliated Hospital.Guangzhou Medical College matched with 10 normal third trimester women as control(control group).The placental DDAH-2 mRNA expression was detected by fluorescence quantitative polymerase chain reaction(FQ-PCR)and the plasma concentration of ADMA WSB determined by high performance liquid chromatography(HPLC).Results(1)The level of ADMA in PE group was significantly higher that than of control group[(18.0±7.2)mg/L vs.(10.3±1.7)mg/L,P<0.01].The expression level of ADMA in preeclampsia occurring before 34 gestatinal weeks WaS significantly higher than that of preeclampsia occurring after 34 gestational weeks[(22.0±7.0)ms/L vs.(12.7±2.8)mg/L,P<0.01].(2)The Placental DDAH-2 mRNA expression in preeclampsia patients was remarkably lower than that of control group[1×10(5.23±0.45)copy/μlvs.1×10(5.65±0.08)copy/μl,P<0.01].The Placental DDAH-2 mRNA in preeclampsia occurring before 34 gestatinal weeks was significantly lower than that of preeclampsia occurring after 34 gestational weeks [1×10(5.02±0.46)copy/μl vs.1×10(5.61±0.19)copy/μl,P<0.01].Conclusion Our results suggested that low expression of DDAH-2 in placenta and increased serum ADMA level might confer the susceptibility to preeclampsia.

PncA mutations in pyrazinamide-resistant Mycobacterium tuberculosis isolates / 中华检验医学杂志

Objective To evaluate the frequency of pncA gene mutations in pyrazinamide-resistant (PZA-resistant)Mycobacterium tuberculosis(M.TB)isolates.Methods The isolates were tested for PZA susceptibility with absolute concentration method.The pncA gene was amplified and the products were cloned into T-vector,followed with sequencing.Results In all the 36 M.TB isolates,there were 25 PZA-resistant strains and 11 PZA-susceptible strains.Mutations of the pncA gene were found in 10 PZA-resistant isolates,four of which belonging to high PZA-resistant strains.The wild type pncA sequence was present in 3 PZA-susceptible strains, synonymous mutations of pncA gene were detected in two PZA-susceptible strains.Additionally,11 PZA-resistant strains and 2 PZA-susceptible ones showed putative regulatory mutations in the upsteam of pncA gene.Condusions The mutation of the pncA gene can cause the PZA resistance.However.there ale other drug resistance mechanism except this mutation.