Bacteriological and molecular typing of Clostridium perfringens strains isolated in retail beef in Beijing, China.

Clostridium perfringens is an important zoonotic pathogen. This study was designed to explore the prevalence and toxin types of C. perfringens in retail beef collected from Beijing, China. Among 221 beef samples collected, 53 samples were positive for C. perfringens, resulting in the average prevalence as 23.98%. By toxin gene-based typing, the most C. perfringens strains belong to type A (96.23%, 51/53), only 2 strains were identified as type D. By a multi-locus sequence typing (MLST)-based analysis, a total of 36 sequence types (STs) were detected, and the most STs (n=30) represented just a single strain. These finding suggested that the prevalence of C. perfringens in retail beef in Beijing was considerably high and these bacteria displayed extreme diversity in genetics.

[Clinical characteristics and genetic analysis of three pediatric patients with idiopathic restrictive cardiomyopathy].

OBJECTIVE: Restrictive cardiomyopathy (RCM) is rare in children, and little is known about the molecular basis of RCM. The aim of this study was to investigate the clinical and myopathological characteristics and to detect mutations on cardiac sarcomere protein genes in three idiopathic pediatric RCMs. METHODS: Detailed clinical characteristics and familiar history were obtained in three idiopathic pediatric RCMs. One hundred healthy pediatric individuals were recruited as controls. Histological evaluation was performed with heart tissue retrieved at catheterization in case-1 and case-2. The entire coding sequences of four cardiac sarcomere protein genes, including cardiac troponin T (TNNT2), cardiac troponin I(TNNI3), ß-myosin heavy chain (MYH7), and α-actin (ACTC)were screened for mutations. Sequence variants were then tested in the family as well as in 100 healthy control DNAs. RESULTS: All three index cases were diagnosed as primary RCMs without family history, and their clinical conditions deteriorated rapidly. Case-1 was in combination with ventricular septal defect. Case-2 was in combination with mid- and inferoseptal hypertrophy. In case-1, myocardial biopsies displayed extensive an isomorphism and disarray of cardiomyocytes; electron microscopy showed large stacks of severely dysmorphic megamitochondria and focal Z-disc streaming. In case-2, endomyocardial biopsy revealed moderate myocyte hypertrophy with mild interstitial fibrosis; transmission electron microscopy showed misalignment of Z-bands and unequal Z-Z band distances. Genetic analysis identified two heterozygous missense mutations in TNNI3, with R204H in case-1 and R192H in case-3 respectively. A de novo heterozygous deletion in TNNT2 (p. Asn100_Glu101del) was identified in case-2. Sequence analysis shows that all three mutations are located in a position highly conserved across many species. The three mutations were negative for their parents and controls. CONCLUSION: The clinical conditions in all three index cases are deteriorated rapidly after diagnosed as primary RCM. Three heterozygous mutations including two in TNNI3 and one in TNNT2 gene are identified in the three RCMs respectively, which are considered as causative mutations. These findings provide new insights into the molecular etiology responsible for pediatric RCM.

[Risk factors for acute fulminant myocarditis in children].

OBJECTIVE: To investigate the risk factors for fulminant myocarditis by analyzing clinical symptoms/signs or laboratory findings in children with viral myocarditis. METHODS: The medical data of 71 children with acute viral myocarditis from March 2005 to September 2008 were retrospectively studied. They were classified into fulminant (n=16) and non-fulminant myocarditis groups (n=55). Chi-square and Student's t-test were used to analyze the clinical presentations, laboratory data, EEG and cardiac ultrasound findings on admission. The multiple regression analysis was used to identify the independent risk factors for fulminant myocarditis. RESULTS: Eight children (50%) died in the fulminant myocarditis group, but none in the non-fulminant group. The following factors were closely related to the fulminant course of myocarditis: lower blood pressure, higher serum CK-MB level, positive cTnI, complete atrioventricular block and left bundle branch block, ST segment alterations, prolonged QRS complex, and decreased left ventricular ejection fraction and short axis fractional shortening. Multiple regression analysis revealed that prolonged QRS complex (OR=1.139; CI=1.014-1.279, P<0.05) and decreased left ventricular ejection fraction (OR=0.711; CI=0.533-0.949, P<0.05) were independent risk factors for fulminant myocarditis. CONCLUSIONS: The mortality of fulminant myocarditis is high in children. Prolonged QRS complex and decreased left ventricular ejection fraction on admission are independent risk factors for fulminant myocarditis in children.

[Matrix metalloproteinase-1 expression in the circulation of patients with Kawasaki disease and its role in the pathogenesis of coronary artery lesions].

OBJECTIVE: Kawasaki disease (KD) is an acute and self-limited systemic vasculitis syndrome of unknown origin that mainly affects small and medium-sized arteries, particularly the coronary arteries, which is followed by aneurysm formation. Increased levels of matrix metalloproteinase-1 (MMP-1) have been detected in aortic aneurysms in adults, suggesting an important role of MMP-1 in arterial wall destruction and resultant aneurysm formation. The aim of this study was to investigate the potential role of MMP-1 in the pathogenesis of coronary artery lesions in patients with KD. METHODS: Forty patients with KD, including 23 patients without coronary artery lesions (CAL) and 17 patients with CAL, as well as age-matched 10 febrile and 10 healthy afebrile controls were studied. The duration of KD was divided into three phases: the acute phase, the subacute phase and the convalescent phase. Enzyme-linked immunosorbent assay was used to detect the protein levels of MMP-1 in the sera. MMP-1 mRNA expression in the circulating leucocytes was studied using reverse transcription-polymerase chain reaction. RESULTS: Levels of MMP-1 protein in serum and MMP-1 mRNA expression in the leucocytes were significantly elevated at the acute phase in the two groups of KD patients (CAL group: 14.91 +/- 3.88 ng/ml and 0.89 +/- 0.15 ng/ml; NO-CAL group: 11.27 +/- 3.28 ng/ml and 0.77 +/- 0.14, respectively), compared with febrile (7.05 +/- 1.98 ng/ml and 0.45 +/- 0.12 ng/ml, respectively) and afebrile (5.13 +/- 1.20 ng/ml and 0.29 +/- 0.12 ng/ml, respectively) controls (P < 0.01). Furthermore, MMP-1 protein and MMP-1 mRNA levels were significantly higher in KD patients with CAL than in KD patients without CAL (P < 0.05). There was a significantly positive correlation between the serum protein level of MMP-1 at the acute phase of KD and the circulating leucocytes counts (r = 0.750, P < 0.01). The MMP-1 serum protein level and mRNA expression in the leucocytes at the acute phase of the two KD groups decreased obviously from the subacute through the convalescent phases (P < 0.05 or P < 0.01). CONCLUSION: The expression of MMP-1 at the acute phase of KD was significantly elevated, especially in KD patients with CAL. MMP-1 might be involved in the formation of coronary artery lesions and pathogenesis of KD.