The expression of microRNAs in mice with myocardial infarction and the evaluation of cardiac function after intervention / 天津医药

@#Objective To detect the expressions of miRNA - 1 and miRNA - 21 and to investigate the relationship between myocardial remodeling and changes of myocardial function. Methods The myocardial infarction model of mice were prepared. Seventy-two model mice were divided into model group (MI group), intervention group 1 (miRNA-1 blockerwas injected into infarct area) and intervention group 2 (miRNA-21 lentivirus carrier was injected into infarct area), 24 mice for each group. The ultrasonic instrument was used to measure the cardiac function indexes of the myocardial infarction model and evaluate the degree of cardiac function and ventricular remodeling. Fluorescence quantitative PCR was used to detect the expressions of miRNA -1 and miRNA-21. Results The expression of miRNA-1 was elevated at 4 weeks after MI, and reached the highest expression level at 12 weeks. The expression of miRNA-1 was decreased in all periods after the injection of miRNA-1 antagonist. MiRNA-21 showed a slight increase in 4 weeks after MI, followed by a decreasing trend. After injection of miRNA–21 lentiviral vectors, the elevated miRNA-21 expression was obtained at various times. After injection with miRNA-1 antagonist, LVDD and LVmass showed improvement in 8 weeks and 12 weeks after MI. LVEF was significantly improved in 8 weeks and 12 weeks. MiRNA-21 lentiviral vectors were injected, and LVDD was reduced in 12 weeks. LVmass and LVEF were significantly improved in 12 weeks after MI. Conclusion In the process of myocardial infarction, miRNA-1 and miRNA-21 are involved in the regulation of heart failure and ventricular remodeling.

Serological and molecular capsular typing, antibiotic susceptibility and multilocus sequence typing of Streptococcus pneumoniae isolates from invasive and non-invasive infections / 中华医学杂志(英文版)

<p><b>BACKGROUND</b>Streptococcus pneumoniae (S. pneumoniae) is a major causative agent of severe infections, including sepsis, pneumonia, meningitis, and otitis media, and has become a major public health concern. We report the pneumococcal serotype and sequence type (ST) distribution, and antimicrobial resistance of 39 S. pneumoniae strains from seven hospitals in China.</p><p><b>METHODS</b>Blood/cerebrospinal fluid (CSF) and sputum isolates from patients were analyzed to determine S. pneumoniae serotypes by polymerase chain reaction (PCR) and the Neufeld Quellung reaction, the multilocus sequence types (MLST) by PCR and sequencing, and susceptibility to antimicrobial agents by the VITEK Gram Positive Susceptibility Card.</p><p><b>RESULTS</b>A total of 39 isolates were collected including 21 blood/CSF and 18 sputum isolates. Conventional serotyping by the Quellung reaction required 749 reactions. In contrast, PCR based typing needed only 106 PCR reactions. The most frequent serotypes from the blood/CSF isolates were 14 (38.1%), 19A (14.3%), 23F (9.5%), and 18C (9.5%). In the sputum isolates the most frequent serotypes were 19F (33.3%), 23F (16.7%), 19A (11.1%), and 3 (11.1%). The incidence of penicillin resistance in the blood/CSF and sputum isolates was 66.7% and 55.6%, respectively. Statistical analysis showed that patients = 5 years old had a higher resistance to penicillin when they compared with the patients = 65 years old (P = 0.011). Serotypes 14, 19A and 19F were significantly associated with penicillin resistance (P < 0.001). ST320, ST271, and ST876 isolates showed high resistant rates to several antibiotics including penicillin (P = 0.006). All of the isolates of serotype 19A were resistant to both penicillin and erythromycin, and they were all multi-drug resistant (MDR) isolates.</p><p><b>CONCLUSIONS</b>The specificity and sensitivity of multiplex-PCR are good, and this method represents a substantial savings of time and money, and can be widely used in the laboratory and clinical practice. Data from this research showed an extremely high prevalence of penicillin resistance and an increasing prevalence of multi-drug resistant (MDR) rate in S. pneumoniae. A distinctive emergence of serotype 19A was observed which was also associated with the increasing prevalence of antimicrobial resistance. Therefore, nationwide surveillance of pneumococcal resistance and serotypes is strongly warranted.</p>

Preliminary molecular epidemiology of the Staphylococcus aureus in lower respiratory tract infections: a multicenter study in China / 中华医学杂志(英文版)

<p><b>BACKGROUND</b>Staphylococcus aureus (S. aureus) remains as an important microbial pathogen resulting in community and nosocomial acquired infections with significant morbidity and mortality. Few reports for S. aureus in lower respiratory tract infections (LRTIs) have been documented. The aim of this study was to explore the molecular epidemiology of S. aureus in LRTIs in China.</p><p><b>METHODS</b>A multicenter study of the molecular epidemiology of S. aureus in LRTIs was conducted in 21 hospitals in Beijing, Shanghai and twelve other provinces from November 2007 to February 2009. All the collected S. aureus strains were classified as minimum inhibitory concentration (MIC), mecA gene, virulence genes Panton-Valentine Leukocidin (PVL) and γ-hemolysin (hlg), staphylococcal cassette chromosome mec (SCCmec) type, agr type, and Multilocus Sequence Typing (MLST).</p><p><b>RESULTS</b>Totally, nine methicillin-sensitive S. aureus (MSSA) and 29 methicillin-resistant S. aureus (MRSA) strains were isolated after culture from a total of 2829 sputums or bronchoalveolar lavages. The majority of MRSA strains (22/29) had a MIC value of ≥ 512 µg/ml for cefoxitin. The mecA gene acting as the conservative gene was carried by all MRSA strains. PVL genes were detected in only one S. aureus strain (2.63%, 1/38). The hlg gene was detected in almost the all S. aureus (100% in MSSA and 96.56% in MRSA strains). About 75.86% of MRSA strains carried SCCmec III. Agr type 1 was predominant (78.95%) among the identified three agr types (agr types 1, 2, and 3). Totally, ten sequence type (ST) of S. aureus strains were detected. A new sequence type (ST1445) was found besides confirming ST239 as the major sequence type (60.53%). A dendrogram generated from our own MLST database showed all the bootstrap values ≤ 50%.</p><p><b>CONCLUSION</b>Our preliminary epidemiology data show SCCmec III, ST239 and agr type 1 of S. aureus as the predominant strains in LRTIs in Mainland of China.</p>

Drug-resistant genes carried by Acinetobacter baumanii isolated from patients with lower respiratory tract infection / 中华医学杂志(英文版)

<p><b>BACKGROUND</b>Acinetobacter baumanii (A. baumanii ) remains an important microbial pathogen resulting in nosocomial acquired infections with significant morbidity and mortality. The mechanism by which nosocomial bacteria, like A. baumanii, attain multidrug resistance to antibiotics is of considerable interest. The aim in this study was to investigate the spread status of antibiotic resistance genes, such as multiple β-lactamase genes and aminoglycoside-modifying enzyme genes, from A. baumanii strains isolated from patients with lower respiratory tract infections (LRTIs).</p><p><b>METHODS</b>Two thousand six hundred and ninety-eight sputum or the bronchoalveolar lavage samples from inpatients with LRTIs were collected in 21 hospitals in the mainland of China from November 2007 to February 2009. All samples were routinely inoculated. The isolated bacterial strains and their susceptibility were analyzed via VITEK-2 expert system. Several kinds of antibiotic resistant genes were further differentiated via polymerase chain reaction and sequencing methods.</p><p><b>RESULTS</b>Totally, 39 A. baumanii strains were isolated from 2698 sputum or bronchoalveolar lavage samples. There was not only a high resistant rate of the isolated A. baumanii strains to ampicillin and first- and second-generation cephalosporins (94.87%, 100% and 97.44%, respectively), but also to the third-generation cephalosporins (ceftriaxone at 92.31%, ceftazidine at 51.28%) and imipenem (43.59%) as well. The lowest antibiotic resistance rate of 20.51% was found to amikacin. The OXA-23 gene was identified in 17 strains of A. baumanii, and the AmpC gene in 23 strains. The TEM-1 gene was carried in 15 strains. PER-1 and SHV-2 genes were detected in two different strains. Aminoglycoside-modifying enzyme gene aac-3-Ia was found in 23 strains, and the aac-6'-Ib gene in 19 strains. aac-3-Ia and aac-6'-Ib genes hibernated in three A. baumanii strains that showed no drug-resistant phenotype.</p><p><b>CONCLUSIONS</b>A. baumanii can carry multiple drug-resistant genes at the same time and result in multi-drug resistance. Aminoglycoside-modifying enzyme genes could be hibernating in aminoglycoside sensitive strains without expressing their phenotype.</p>

Osmic acid staining of myelin sheath in normal and regenerated peripheral nerves / 中华创伤杂志(英文版)

<p><b>OBJECTIVE</b>To introduce a practical, economical, and time-saving method to stain (with osmic acid) the myelin sheath in normal and regenerated peripheral nerves.</p><p><b>METHODS</b>A total of 12 Sprague Dawley rats, weighing 250-320 g (mean equal to 276 g+/-38 g), were divided into two groups: a normal nerve group (n equal to 6) and a regenerated nerve group (n equal to 6). In the normal nerve group, the ventral and dorsal roots of L(4) to L(6) and their sciatic nerves were harvested for histological analysis. While in the regenerated nerve group, the right sciatic nerves were severed and then repaired with an epineurial microsuture method. The repaired nerves were harvested 12 weeks postoperatively. All the specimens were fixed in 4% paraformaldehyde and transferred to 2% osmic acid for 3-5 days. Then the specimens were kept in 75% alcohol before being embedded in paraffin. The tissues were cut into sections of 3 micromolar in thickness with a conventional microtome.</p><p><b>RESULTS</b>Under a light microscope, myelin sheaths were clearly visible at all magnifications in both groups. They were stained in clear dark colour with a light yellow or colorless background, which provided high contrast images to allow reliable morphometric measurements. Morphological assessment was made in both normal and regenerated sciatic nerves. The ratios of the myelin area to the fibre area were 60.28%+/-7.66% in the normal nerve group and 51.67%+/-6.85% in the regenerated nerve group, respectively (P less than 0.01).</p><p><b>CONCLUSIONS</b>Osmic acid staining is easy to perform and a very clear image for morphometrical assessment is easy to obtain. Therefore, it is a reliable technique for quantitative evaluation of nerve morphology.</p>