Molecular epidemiology of serotype 19A Streptococcus pneumoniae isolated from children in Beijing, 1997–2006

Background  Despite the prevalence of Streptococcus pneumoniae serotype 19A, the molecular characteristics of this serotype are yet to be fully elucidated. The aim of this study was therefore to determine the homology of the serotype 19A in China.

Methods  Pulsed-field gel electrophoresis and multilocus sequence typing were done to these forty-nine serotype 19A isolates to investigate the relationship between the strains prevalent in Beijing and other regions.

Results  From 1997 to 2006, the percentage of serotype 19A isolates increased. The susceptibility rate to penicillin and amoxicillin decreased and the resistance rate to cefuroxime increased. ST320 was the most prevalent ST, followed by ST3546. There were six new STs identified in our study. The serotype 19A strains were classified into six different pulsed-field gel electrophoresis (PFGE) patterns. ST320, which was associated with two different PFGE patterns (A and D), accounted for 32 isolates, and ST3546, which was associated with two PFGE patterns (B and E), accounted for eight isolates.

Conclusions  From 2003 onwards, ST320 was the most common ST and the rate of resistance to cefuroxime increased significantly. Further long-term surveys of Streptococcus pneumoniae serotype 19A are required to monitor ST prevalence and antimicrobial resistance in this important human pathogen.

     

Characterization of erythromycin-resistant Streptococcus pneumoniae isolates causing invasive diseases in Chinese children

Background  Erythromycin-resistant Streptococcus pneumoniae isolates that causing invasive pneumococcal diseases (IPD) in Chinese children remain uncharacterized. This study aims to identify the resistance genes associated with erythromycin resistance and to determine the genetic relationships of IPD isolates in Chinese children.

Methods  A total of 171 S. pneumoniae strains were isolated from 11 medical centers in China from 2006 to 2008. All the isolates were characterized via serotyping and antibiotic susceptibility determination. The erythromycin-resistant isolates were further characterized via ermB and mefA gene detection, multi-locus sequence typing analysis, and pulsed-field gel electrophoresis.

Results  A total of 164 (95.9%) isolates showed resistance to erythromycin, of which 162 strains with high high-level resistance (MIC ≥ 256 μg/ml). A total of 104 (63.4%) isolates carry the ermB gene alone, whereas 59 (36.0%) harbor both ermB and mefA genes. Of the 59 strains, 54 were of serotypes 19A and 19F and were identified as highly clonal and related to the Taiwan^19F-14 clone.

Conclusions The erythromycin resistance rate in IPD isolates is significantly high and is predominantly mediated by the ermB gene. Isolates that carry both ermB and mefA genes are predominantly of serotypes 19A and 19F.

     

Molecular epidemiology of Mycobacterium tuberculosis in Gansu province of China

Background  Mycobacterial interspersed repetitive units-variable number tandem repeat (MIRU-VNTR) and Beijing family typing based on detecting the deletion of RD105 sequence are two common genotyping methods used to study the molecular epidemiologic characteristics of Mycobacterium (M.) tuberculosis. We collected 218 strains of M. tuberculosis between 2004 and 2006 in the Linxia Hui Autonomous Prefecture of Gansu province in Northwest China.

Methods  MIRU-VNTR analysis and Beijing family typing based on detecting the deletion of RD105 sequence were used to type the 218 strains, and their typing power was evaluated to look for practical and efficient genotyping methods suitable for the region.

Results  The MIRU typing yielded 115 distinct genotypes, including 98 unique isolates and 17 different clusters containing 120 isolates (55.05%); the cluster rate was 47.25%. By detecting the deletion of RD105 sequence, 188 of 218 (86.23%) isolates belonged to Beijing family. Combination of Beijing family typing and MIRU typing yielded 118 distinct patterns, including 101 unique isolates and 17 clusters containing 117 isolates (54.13%). The largest cluster contained 58 strains with MIRU genotype of 223325173533 which contained 50 strains belonging to Beijing family and 8 strains belonging to non-Beijing family.

Conclusions  The Beijing family strains occupied a large proportion and the Beijing family MIRU genotype 223325173533 is a dominant strain in Linxia of Gansu. Combining detecting the deletion of RD105 and MIRU typing together provides a simple, fast, and effective method which is low in cost and might be practical and suitable for M. tuberculosis genotyping in China.

     

Malocclusions in Xia Dynasty in China

Background  The prevalence of malocclusion in modern population is higher than that in the excavated samples from the ancient times. Presently, the prevalence of juvenile malocclusion in the early stage of permanent teeth is as high as 72.92% in China. This study aimed to observe and evaluate the prevalence and severity of malocclusions in a sample of Xia Dynasty in China, and to compare these findings with the modern Chinese population.

Methods  The material consisted of 38 male and 18 female protohistoric skulls of Xia Dynasty 4000 years ago. Of 86 dental arches, 29 cases had the jaw relationships. Tooth crowding, diastema, individual tooth malposition and malocclusion were studied.

Results  Of the samples, 23.3% showed tooth alignment problems including crowding (8.1%), diastema (9.3%), and individual tooth malposition (5.8%). The prevalence of malocclusion was 27.6%, mainly presented as Angle Class I.

Conclusions  It is indicated that over thousands of years from Neolithic Age (6000–7000 years ago) to Xia Dynasty (4000 years ago), the prevalence of malocclusion did not change significantly. The prevalence of malocclusion of Xia Dynasty samples was much lower than that of modern population.

     

Clinical study of distribution and drug resistance of pathogens in patients with severe acute pancreatitis

Background  Previous researches about necrotic pancreatic tissue infections are numerous, but the study on systemic infection related to the severe acute pancreatitis (SAP) treatment period is limited. This study aimed to investigate the distribution and drug resistance of pathogenic bacteria in patients who had hepatobiliary surgery for SAP during the past three years. 

Methods  A retrospective study was conducted on the distribution, category and drug resistance of pathogenic bacteria in patients who had hepatobiliary surgery for SAP from 2008 to 2011. 

Results  A total of 594 pathogenic bacteria samples were isolated. Among them 418 isolates (70.4%) were Gram bacteria negative, 142 isolates (23.9%) were Gram bacteria positive, and 34 isolates (5.7%) were found fungi. The most common Gram negative bacteria were Escherichia coli (19.8%), and the dominant Gram positive pathogenic bacteria were Enterococcus faecium. The distribution of SAP-related infectious pathogens was mainly in peritoneal drainage fluid, sputum, bile, and wound secretions. Almost all the Gram negative pathogenic bacteria were sensitive to carbapenum. Extended-spectrum β-lactamases (ESBLs) producing strains were more resistant to penicillins and cephalosprins than the ESBLs non-producing strains. Staphylococcus was sensitive to vancomycin and linezolid. The drug resistance of meticillin-resistant staphylococcus (MRS) to commonly used antibiotics was higher than meticillin-sensitive streptococcus (MSS). Enterococcus sp. exhibited lower drug-resistance rates to vancomycin and linezolid.

Conclusions  Gram negative bacteria were the dominant SAP-related infection after hepatobiliary surgery. A high number of fungal infections were reported. Drug resistant rates were high. Rational use of antibiotics according to the site of infection, bacterial species and drug sensitivity, correctly executing the course of treatment and enhancing hand washing will contribute to therapy and prevention of SAP-related infection and decrease its mortality.

     

Prevalence of low back pain among soldiers at an army base

Background  Low back pain (LBP) is a major medical and social problem among working populations and is associated with high medical expense, loss of productivity, and disability. The aim of this study is to investigate the prevalence of LBP among soldiers and evaluate the possible causative factors in military training. The results may provide an insight into changes needed in military training that will reduce the occurrence of LBP among soldiers.

Methods  A cross-sectional survey was conducted in a group of young soldiers in China to estimate the prevalence of LBP and evaluate possible causative factors in military training.

Results  The survey was distributed to 1659 soldiers, of whom 1624 responded. LBP was reported by 425 of the 1624 (26.2%) soldiers. The prevalence of LBP was higher in the armored force (51.3%) than in the artillery (27.5%) or infantry (11.9%). A multivariate logical regression analysis identified night training, 5 km cross-country race, and grenade-throwing training as military training risk factors for LBP.

Conclusions  The relatively high incidence of LBP among soldiers was related to night training, 5 km racing, and grenade throwing. Modifications in these training methods should enhance the health of recruits and lower the incidence of LBP.

     

Etiology and antimicrobial resistance of community-acquired pneumonia in adult patients in China

Background  Appropriate antimicrobial therapy of community-acquired pneumonia (CAP) is mainly based on the distribution of etiology and antimicrobial resistance of major pathogens. We performed a prospective observational study of adult with CAP in 36 hospitals in China.

Methods　Etiological pathogens were isolated in each of the centers, and all of the isolated pathogens were sent to Zhongshan Hospital for antimicrobial susceptibility tests using agar dilution.

Results  A total of 593 patients were enrolled in this study, and 242 strains of bacteria were isolated from 225 patients. Streptococcus pneumoniae (79/242, 32.6%) was the most frequently isolated pathogen, followed by Haemophilus influenzae (55/242, 22.7%) and Klebsiella pneumoniae (25/242, 10.3%). Totally 527 patients underwent serological tests for atypical pathogens; Mycoplasma pneumoniae and Chlamydia pneumoniae infections were identified in 205 (38.9%) and 60 (11.4%) patients respectively. Legionella pneumophila infections were identified in 4.0% (13/324) of patients. The non-susceptibility rate of isolated Streptococcus pneumoniae to erythromycin and penicillin was 63.2% and 19.1% respectively. Six patients died from the disease, the 30-day mortality rate was 1.1% (6/533).

Conclusions  The top three bacteria responsible for CAP in Chinese adults were Streptococcus pneumonia, Haemophilus influenza and Klebsiella pneumonia. There was also a high prevalence of atypical pathogens and mixed pathogens. The resistance rates of the major isolated pathogens were relatively low except for the high prevalence of macrolide resistance in Streptococcus pneumoniae.

     

Genetic diversity analysis of Penicillium marneffei isolated from AIDS patients in Guangdong, China using randomly amplified polymorphic DNA

Background  Penicillium marneffei (P. marneffei) is an emerging pathogenic fungus that can cause invasive mycosis in patients with AIDS. The epidemiological features of P. marneffei infection in AIDS patients in Guangdong province remain unclear so far. This study aimed to investigate the genetic diversity within a population of 163 P. marneffei isolates obtained from AIDS patients and search for the dominant clinical strains in Guangdong province.

Methods  One hundred and sixty-three P. marneffei isolates obtained from AIDS patients in Guangdong province during January 2004 and December 2009 were studied by randomly amplified polymorphic DNA (RAPD) using two random primers (H2 and H22). The degree of similarity between samples was calculated through similarity coefficients from RAPD fragment data and the dendrogram was assessed using the unweighted pair group method with arithmetic mean (UPGMA).

Results  Two primers showed a high degree of discrimination and good stability. Primer H2 yielded eight different patterns (H2-1 to H2-8) among 163 isolates with the discriminatory power being 0.413. Primer H22 identified seven types (H22-1 to H22-7) among 163 isolates with the discriminatory power being 0.467. Genetic similarity coefficients based on RAPD data among 163 P. marneffei isolates ranged from 0.681 to 0.957, 61.96% of which were no less than 0.83. The discriminatory power of the two primers was 0.524. One hundred and sixty-three P. marneffei isolates were clustered into nine distinct groups (groups I to IX) at the similarity coefficient value of 0.83 and group I was the most common, including 101 strains (61.96%).

Conclusion  The RAPD analyses could provide important information as to the degree of genetic diversity and the relationship among clinical P. marneffei isolates, revealing genetic polymorphism and dominant strains.

     

Influence of dental restorative material properties on bond interface reliability: a finite element analysis

 

Background  Varieties of restorative materials are widely used in dentistry. The aim of this study is to explore the influence of different dental restorative materials on bond interface reliability.

Methods  A two-dimensional finite element analysis method was adopted to simulate the shear-bond efficacy test. The influence of elastic modulus and Poisson’s ratio were investigated separately. Several dental restorative materials including resins, metals, and ceramics were analyzed in this study.

Results  The deformation and peak equivalent stress level of the dentin-adhesive interface rose sharply following a decrease in the elasticity of restorative materials, especially those with a low elastic modulus range. The influence of the Poisson’s coefficient was not significant. Ceramics and gold alloy were preferred to resin composite in restorations bearing extensive shear load during service.

Conclusions  Restorative materials with an elastic modulus similar to that of teeth are not always the best clinical choice. This research provides a helpful guide for the application of different restorative materials in clinical practice.

     

Different treatment modalities of fusiform basilar trunk aneurysm: study on computational hemodynamics

Background  Unclippable fusiform basilar trunk aneurysm is a formidable condition for surgical treatment. The aim of this study was to establish a computational model and to investigate the hemodynamic characteristics in a fusiform basilar trunk aneurysm.

Methods  The three-dimensional digital model of a fusiform basilar trunk aneurysm was constructed using MIMICS, ANSYS and CFX software. Different hemodynamic modalities and border conditions were assigned to the model. Thirty points were selected randomly on the wall and within the aneurysm. Wall total pressure (WTP), wall shear stress (WSS), and blood flow velocity of each point were calculated and hemodynamic status was compared between different modalities.

Results  The quantitative average values of the 30 points on the wall and within the aneurysm were obtained by computational calculation point by point. The velocity and WSS in modalities A and B were different from those of the remaining 5 modalities; and the WTP in modalities A, E and F were higher than those of the remaining 4 modalities.

Conclusions  The digital model of a fusiform basilar artery aneurysm is feasible and reliable. This model could provide some important information to clinical treatment options.

     

Stereotactic aspiration and thrombolysis of spontaneous intracerebellar hemorrhage

Background  Spontaneous intracerebellar hemorrhage (SCH) accounts for 10% of intracerebral hemorrhages. Up to now stereotactic aspiration and thrombolysis of SCH was less reported. The aim of this study was to assess the effect and feasibility of the method, and to refine the clinical protocol.

Methods  Eighteen patients with SCH were treated by stereotactic aspiration and thrombolysis and reviewed in this report. The 3-mm axial stereotactic computed tomography slices throughout the hematoma were obtained. Those images were then transferred to the workstation. The trajectory of catheter was designed to go through the main axis of the hematoma. Under local anesthesia a catheter was directed stereotactically into the hematoma through a burr hole. Hematoma thrombolysis and clot drainage was followed by instillation of urokinase (10 000 U) every 12 hours. The catheter was removed when the majority of hematoma was evacuated.

Results  Initial SCH volume was reduced by an average of 86% and the average final hematoma volume was 2.8 ml. At 3-month follow-up, 13 patients (72%) had achieved good recovery. At 6-month follow-up, 12 patients (67%) had achieved good recovery.

Conclusion  Stereotactic aspiration and thrombolysis of SCH was a simple, feasible and effective method to treat moderate and some benign SCH that less respond to medical treatment.

     

HIV prevalence and influencing factors analysis of sentinel surveillance among men who have sex with men in China, 2003–2011

Background  Men who have sex with men (MSM) have been impacted by HIV and now as an important driver of the HIV/AIDS epidemic in China. This study collected HIV sentinel surveillance system data on the MSM population to describe the characteristics and trends of the HIV epidemic among MSM in China from 2003 to 2011.

Methods  Data on HIV prevalence and risk behaviors from 2003 to 2011 were obtained from the national HIV sentinel surveillance database.

Results  MSM sentinel surveillance data for 2011 showed that proportions of MSM who consistently used condoms during anal sex in the last six months and at last anal sex encounter were 43.3% and 74.1%, respectively. Between 2005 and 2011 there were no significant changes in the proportion of consistent condom use. The proportion of MSM who had multiple male sex partners in the last six months increased. Overall HIV prevalence over the years showed a rising trend from 0.9% in 2003 to 6.3% in 2011. The syphilis antibody positive rate was 7.8% in 2011. In addition, the proportion of MSM in heterosexual marriages was rising, AIDS awareness was also increasing, and the proportion of MSM who had taken an HIV test in the last year and was aware of the results rose. The proportion who had received intervention services in the last year stabilized.

Conclusions  HIV prevalence in MSM populations is rapidly and widely distributed. MSM who are in heterosexual marriages may be a bridge group transmitting HIV to their heterosexual partners. The risky sexual behavior among MSM will remain a serious and important driver of China’s AIDS epidemic over the next period of time. Intervention need to be strengthened, as does the effective implementation of measures to control AIDS and prevent it from spreading further.

     

Specific regulator of eosinophil apoptosis: Siglec-8—new hope for bronchial asthma treatment

Objective  It is known that Siglec-8 is selectively expressed on human eosinophils at a high level and mediates eosinophil apoptosis when crosslinked with its antibody. The aim of our review is to elucidate the molecular and biological characteristic of Siglec-8 and then discuss the function and possible mechanisms of Siglec-8 in eosinophils. Thereby, we will expand our understanding to the regulation of eosinophil apoptosis, and provide important clues to the treatment of asthma and other hyper-eosinophilic diseases.

Data sources  Most articles were identified by searching of PubMed online resources using the key term Siglecs.

Study selection  Mainly original milestone articles and critical reviews written by major pioneer investigators in the field were selected.

Results  Siglec-8 is selectively expressed on human eosinophil and can specifically induce eosinophil apoptosis.

Conclusion  The restricted expression of Siglec-8 on human eosinophil and the rapid progress in understanding its role as cell signaling and activation of death receptors have made it an attractive target for treatment of asthma and other hyper-eosinophilic diseases.

     

Molecular mechanism of indirubin-3′-monoxime and Matrine in the reversal of paclitaxel resistance in NCI-H520/TAX25 cell line

Background  Multidrug resistance (MDR) is a main reason for paclitaxel (TAX) treatment failure. Indirubin-3′-monoxime (IRO) and Matrine are traditional Chinese medicines, which may reverse the resistance of tumor cells to some chemotherapy drugs, but the relationship between paclitaxel resistance and Matrine is still unclear. The aim of this study was to explore the potential molecular mechanism of IRO and Matrine in reversal of TAX resistance.

Methods  In this study, MTT assay was used to measure the non-cytotoxic dosage of IRO and Matrine on NCI-H520/TAX25 cells and determine the reversal extent of TAX resistance under non-toxic doses. In addition, RT-PCR and Western blotting were used to evaluate the mRNA expression and the protein level of survivin, Oct-4, and Sox-2 in NCI-H520/TAX25 cells using semi-quantitative methods.

Results  There was no obvious inhibition on sensitive cell strains and drug-resistant strains, when the final concentration was at lest 4 µmol/L for IRO and 100 µmol/L for Matrine. So 4 µmol/L of IRO and 100 µmol/L of Matrine were considered as the reversal dosage. When 4 µmol/L of IRO or 100 µmol/L of Matrine were used together with TAX, the sensitivity to TAX increased evidently in NCI-H520/TAX2 cells; the reversal rate of IRO and Matrine was about 1.92 (43.56/22.6 nmol/L) and 1.74 (43.56/25.0 nmol/L), respectively. The mRNA expression and the protein level of survivin, Oct-4, and Sox-2 in NCI-H520/TAX25 decreased significantly (P <0.05) after addition of IRO or Matrine in TAX treatment, compared to that of TAX treatment alone.

Conclusion  The decrease in both mRNA expression and protein level of survivin, Oct-4, and Sox-2 might be the molecular mechanism, by which IRO and Matrine mediate the reversal of TAX resistance.

     

Bleb-associated endophthalmitis treated by sclera patch graft, vitrectomy and endoscopic cyclophotocoagulation

Background  Bleb-associated endophthalmitis (BAE) is a rare but severe complication of trabeculectomy with poor outcome. Various surgical methods were explored to treat such patients. However, there is no defined protocol. The aim of this study was to describe a new combined operation, and to demonstrate the outcome of the treatment.

Methods  Nine patients with BAE were enrolled in our study. The combined operation including pars plana vitrectomy (PPV), sclera patch graft (SPG) and endoscopic cyclophotocoagulation (ECP) was used to treat these patients.

Results  In the follow-up of 18–24 months, all patients with the endophthalmitis were cured, the useful visual acuity was preserved in 7 patients, and the intraocular pressure (IOP) of 8 patients was controlled just after first operation, only one needed another trans-scleral cyclophotocoagulation.

Conclusion  This combined operation is a useful method for treating the patients with BAE, with SPG and vitrectomy to control the endophthalmitis and ECP to balance the postoperative IOP.

     

Chemoresistance of CD133+ cancer stem cells in laryngeal carcinoma

Background  Mounting evidence suggests that tumors are histologically heterogeneous and are maintained by a small population of tumor cells termed cancer stem cells. CD133 has been identified as a candidate marker of cancer stem cells in laryngeal carcinoma. This study aimed to analyze the chemoresistance of CD133⁺ cancer stem cells.

Methods  The response of Hep-2 cells to different chemotherapeutic agents was investigated and the expression of CD133 was studied. Fluorescence-activated cell sorting analysis was used to identify CD133, and the CD133⁺ subset of cells was separated and analyzed in colony formation assays, cell invasion assays, chemotherapy resistance studies, and analyzed for the expression of the drug resistance gene ABCG2.

Results  About 1%–2% of Hep-2 cells were CD133⁺ cells, and the CD133⁺ proportion was enriched by chemotherapy. CD133⁺ cancer stem cells exhibited higher potential for clonogenicity and invasion, and were more resistant to chemotherapy. This resistance was correlated with higher expression of ABCG2.

Conclusions  This study suggested that CD133⁺ cancer stem cells are more resistant to chemotherapy. The expression of ABCG2 could be partially responsible for this. Targeting this small population of CD133⁺ cancer stem cells could be a strategy to develop more effective treatments for laryngeal carcinoma.

     

Aging performances for resisting low-temperature of three dental yttria-stabilized zirconia ceramic core materials

Background  The low-temperature resistance aging performance of Yttria-stabilized tetragonal zirconia polycrystal (Y-TZP) is the key effective factor that influences the long-term success rate of prosthesis. The objective of this study was to test and compare the aging performances for resisting low temperature of Lava Frame, Cercon Smart, and Upcera Yttria-stabilized zirconia core materials, via analyzing the micro and the crystal phases of the materials, and measure the three-point bending strength and the fracture toughness.

Methods  The three zirconia green bodies were prepared as 60 test samples for three-point bending strength and as 60 test samples for fracture toughness. The test samples for three-point bending strength and fracture toughness were assigned to five groups and were treated respectively for 0, 5, 10, 15, and 20 hours to observe the micro and the crystal phases of the test samples. Then the three-point bending strength and fracture toughness were tested by X-ray diffraction (XRD).

Results  The m phase content of Lava Frame was raised from 7.70% to 13.01%; the m phase content of Cercon Smart was raised from 4.95% to 8.53%; and Lava Frame is raised from 10.84% to 35.18%. The three-point bending strengths of the three zirconia core materials were higher than 1100 MPa and the fracture toughness was higher than 3 MPa·m^1/2. The three-point bending strength and the fracture toughness of Upcra zirconia decreased the most, followed by Lava Frame, and then by Cercon Smart.

Conclusion  The aging resistance sequences of the three zirconia core materials are, from strong to weak, Cercon Smart, Lava Frame, and Upcera.

     

Visualization of Medpor implants using surface rendering

Background  The Medpor surgical implant is one of the easiest implants in clinical practice, especially in craniomaxillofacial surgery. It is often used as a bone substitute material for the repair of skull defects and facial deformities. The Medpor implant has several advantages but its use is limited because it is radiolucent in both direct radiography and conventional computed tomography, causing serious problems with visualization. 

Methods  In this study, a new technique for visualizing Medpor implants was evaluated in 10 patients who had undergone facial reconstruction using the material. Continuous volume scans were made using a 16-channel tomographic scanner and 3D reconstruction software was used to create surface renderings. The threshold values for surface renderings of the implant ranged from –70 HU to –20 HU, with bone as the default. 

Results  The shape of the implants and the spatial relationship between bone and implant could both be displayed.

Conclusion  Surface rendering can allow successful visualization of Medpor implants in the body.