ClpP affects biofilm formation of Streptococcus mutans differently in the presence of cariogenic carbohydrates through regulating gtfBC and ftf.

The abilities to form biofilms on teeth surface and to metabolize a wide range of carbohydrates are key virulence attributes of Streptococcus mutans. ClpP has been proved to play an important role in biofilm development in streptococci. Here we demonstrated that ClpP was involved in biofilm formation of S. mutans. ClpP inactivation resulted in enhanced biofilm formation or initial cell adherence in broth supplemented with sucrose, while reduced in broth supplemented with glucose or fructose. Our results also indicated that the enhanced capacities of biofilm formation and initial cell adherence were achieved through regulating the expression of a number of extracellular sucrose-metabolizing enzymes, such as glucosyltransferases (GTFB and GTFC) at early-exponential growth phase and fructosyltransferase at late-exponential growth phase in the presence of sucrose.

Contribution of ClpP to stress tolerance and virulence properties of Streptococcus mutans.

Abilities to tolerate environmental stresses and to form biofilms on teeth surface are key virulence attributes of Streptococcus mutans, the primary causative agent of human dental caries. ClpP, the chief intracellular protease of S. mutans, along with ATPases degrades altered proteins that might be toxic for bacteria, and thus plays important roles in stress response. To further understand the roles of ClpP in stress response of S. mutans, a ClpP deficient strain was constructed and used for general stress tolerance, autolysis, mutacins production, and virulence assays. Here, we demonstrated that inactivation of ClpP in S. mutans resulted in a sensitive phenotype to several environmental stresses, including acid, cold, thermal, and oxidative stresses. The ClpP deficient strain displayed slow growth rates, poor growth yields, formation of long chains, increased clumping in broth, and reduced capacity to form biofilms in presence of glucose. Mutacins production and autolysis of S. mutans were also impaired by mutation of clpP. Animals study showed that clpP mutation increased virulence of S. mutans but not significant. However, enhanced abilities to survive lethal acid and to form biofilm in sucrose were observed in ClpP deficient strain. Our findings revealed a broad impact of ClpP on several virulence properties of S. mutans and highlighted the relevance of ClpP proteolysis with progression of diseases caused by S. mutans.

Epoetin delta reduces oxidative stress in primary human renal tubular cells.

Erythropoietin (EPO) exerts (renal) tissue protective effects. Since it is unclear whether this is a direct effect of EPO on the kidney or not, we investigated whether EPO is able to protect human renal tubular epithelial cells (hTECs) from oxidative stress and if so which pathways are involved. EPO (epoetin delta) could protect hTECs against oxidative stress by a dose-dependent inhibition of reactive oxygen species formation. This protective effect is possibly related to the membranous expression of the EPO receptor (EPOR) since our data point to the membranous EPOR expression as a prerequisite for this protective effect. Oxidative stress reduction went along with the upregulation of renoprotective genes. Whilst three of these, heme oxygenase-1 (HO-1), aquaporin-1 (AQP-1), and B-cell CLL/lymphoma 2 (Bcl-2) have already been associated with EPO-induced renoprotection, this study for the first time suggests carboxypeptidase M (CPM), dipeptidyl peptidase IV (DPPIV), and cytoglobin (Cygb) to play a role in this process.

[Diagnostic Value of MPV, PDW, PAIg and Their Combination for Megakaryocyte Dysmaturity in Children with Acute Immune Thrombocytopenic Purpura].

OBJECTIVE: To investigate the changes of mean platelet volume (MPV), platelet distribution width (PDW) and platelet associated antibodies (PAIg) in children with acute immune thrombocytopenic purpura (aITP), and to explore the diagnostic value of MPV, PDW, PAIg and their combination for megakaryocyte dysmaturity in aITP children. METHODS: Plt count, MPV and PDW of 36 aITP children were measured by using Sysmex XN automatic blood cell analyzer, and 33 children with acquired thrombocytopenic purpura (ATP) without megakaryocyte dysmaturity. The expression of PAIg was detected by flow cytometry, and the number and classification of megakaryocytes in the bone marrow were performed by marrow cytology. The diagnostic significances of MPV, PDW, PAIg and their combination as well as the sensitivity and specificity for megakaryocytes dysmaturity in aITP were assessed through calculating the area under ROC curve (AUC), after determining the influence of each parameters on the megakaryocyte dysmaturity by Logistic regression. RESULTS: MPV, PDW and PAIg of aITP children were significantly higher than those of the ATP children (P＜0.05), while the Plt count and number of thromocytogenic megakaryocytes per area (1.5 cm×3 cm) were less than those of the controls (P＜0.05). Count of RBC and WBC, percentages of neutrophil granulocytes and lymphocydes in aITP were similar to those in the controls（P＞0.05）. The results of Logistic regression showed that Plt count, MPV, PDW and PAIg were the factors influencing megakaryocyte dysmaturity in aITP children, and the regression model has a high statistical significance (χ2=65.491，P=0.001) and r square (R2=0.713). The AUC of the combined detection of Plt count, MPV, PDW and PAIg was 0.863, which was much higher than that of Plt count, MPV, PDW, PAIg individually or in pairs. The sensitivity and specificity of the combined detection were 79.167% and 89.697%, which were higher than those of Plt count, MPV, PDW, PAIg individually or in pairs. CONCLUSION: The diagnostic significance of MPV and PDW for megakaryocyte dysmaturity in aITP are insufficient, but the diagnostic efficacy can be improved by combined examination with PAIg.

[Effects of valsartan, mycophenolate mofetil and their combined application on TRAIL and nuclear factor-kappaB expression in the kidneys of diabetic rats].

OBJECTIVE: To evaluate the expression of TNF-related apoptosis inducing ligand (TRAIL) and nuclear factor (NF)-kappaB in the kidney tissues of diabetic rats and the effects of valsartan, mycophenolate mofetil (MMF), and their combined application on the renal TRAIL and NF-kappaB expression. METHODS: Eighty uninephrectomized male Wistar rats were randomly divided into 2 groups: normal control (NC) group (n = 28), undergoing intraperitoneal injection of citric acid buffer, and diabetes mellitus (DM) group, undergoing intraperitoneal injection of streptozotocin (STZ) to establish DM models. The 52 DM rats were randomly divided into 7 equal subgroups: DM without treatment for 4 weeks (DM4), DM without treatment for 8 weeks (DM8) DM without treatment for 12 weeks (DM12) , and DM without treatment for 16 weeks (DM16), valsartan treatment (DM + V), MMF treatment (DM + M), and combined treatment (DM + V + M). The treatment subgroups were treated for 8 weeks immediately after the diabetic models ere established. Twenty-four hour urine was collected to measure the amount of protein 4, 8, 12, and 16 weeks after the induction of DM respectively. The rats were sacrificed. Blood samples were collected from the abdominal aorta to detect the blood urea nitrogen (BUN), serum creatinine (sCr), albumin, and glucose. The kidneys were taken out. Hypertrophy index (left kidney weight/body weight) was determined. Quantitative real time RT-PCR was performed to detect the expression of TRAIL and NF-kappaB mRNA. Immunohistochemistry was used to detect the protein expression of TRAIL and NF-kappaB. RESULTS: 1) The 24 h urine protein levels and hypertrophy indexes of all DM subgroups were significantly higher than those of the NC groups (all P <0.05). 24 h urine protein and hypertrophy index increased gradually and peaked in the l2th week; blood albumin gradually decreased since the 8th week(P <0.01), and BUN and sCr began to decrease only since the 16th week (both P <0.01). Compared with the DM 8 subgroup, the hypertrophy index and 24 h urine protein of the different treatment subgroups, especially the DM + V + M subgroup, were significantly lower (all P <0.05). 2) Quantitative real time RT-PCR showed that compared with the NC group, the TRAIL expression levels of the DM subgroups were significantly lower before the 12th week after induction of DM model (all P < 0.01), and then significantly higher in the 16th week (all P < 0.01). The TRAIL expression of the treatment groups, especially that of the DM + M subgroup, were significantly higher than that of the DM8 group (all P <0.05). Compared with the NC group, the NF-kappaB expression levels of the DM subgroups were significantly higher time-dependently (all P <0.01). Compared with the DM8 group, the NF-kappaB expression levels of the treatment subgroups, especially that of the DM + V + M subgroup were significantly lower (all P <0.05). 3) The expression of TRAIL was mainly located in the convoluted tubule of kidney, and no TRAIL protein expression was detected in the glomeruli or renal vasculature. The levels of NF-kappaB protein expression, shown in glomeruli and convoluted tubules, of all DM subgroups were all higher than that of the NC group. The NF-kappaB protein expression level of the DM + V + M subgroup was significantly lower. The number of NF-kappaB positive cells was significantly related to the mononuclear macrophage infiltration , kidney function, and structural lesion. CONCLUSION: An important monitoring factor in the autoimmune system, TRAIL closely participates in the pathogenesis of diabetic nephropathy, possibly controlled by NF-kappaB. In the early stage combination of valsartan and MMF may upregulate the expression of TRAIL, thus protecting the kidney function.

Effects of mycophenolate mofetil, valsartan and their combined therapy on preventing podocyte loss in early stage of diabetic nephropathy in rats.

BACKGROUND: Podocyte has inflammatory role in the development of diabetic nephropathy (DN). Mycophenolate mofetil (MMF), an anti-inflammatory agent, can suppress macrophage infiltration and reduce renal injury in streptozotocin-induced diabetic rats. Angiotensin II receptor blocker (ARB), another renal protecting agent, can decrease podocyte loss in DN. In this study, we detected the expression levels of monocyte chemoattractant protein-1 (MCP-1) and nephrin to evaluate podocyte's role in inflammatory reaction in DN, observe and compare the effect of MMF alone and in combination with valsartan, on preventing podocyte loss in streptozotocin (STZ) induced diabetic rats. METHODS: Diabetic model was constructed in uninephrectomized male Wistar rats by single peritoneal injection of STZ (65 mg/kg). The successfully induced diabetic rats were randomly divided into four groups: diabetes without treatment group (DM), valsartan treated group (DMV), MMF treated group (DMM), and combined therapy group (DMVM). Normal rats of the same sibling were chosen as control (NC). At the end of the 8th week, serum biochemistry, 24-hour urinary protein (UP) and the ratio of kidney weight/body weight (RWK/B) were measured. The rats were sacrificed for the observation of renal histomorphology through light and electron microscope. Nephrin, desmin and MCP-1 levels were detected by semi-quantitative immunohistochemical assays. Real-time quantitative PCR was used to detect the mRNA levels of nephrin and MCP-1. RESULTS: Compared with group NC, serum glucose level, 24-hour UP and RWK/B in group DM were significantly higher (P < 0.01), and the nephrin mRNA level in DM group was significantly lower (P < 0.05). The nephrin mRNA expression levels in group DMV, DMM and DMVM were all higher than that of DM group (P < 0.05) and no significant differences were found among the three treatment groups (P > 0.05). Treatment with MMF, valsartan or their combination could significantly decrease the 24-hour UP and RWK/B, and suppress glomerulosclerosis and interstitial fibrotic lesions in diabetic rats. In diabetic rats, the high expressions of desmin and MCP-1 in kidney were suppressed by valsartan, MMF or their combination. CONCLUSIONS: Podocytes are involved in the inflammatory reaction of diabetic rats. MMF could suppress MCP-1 and desmin expression, enhance nephrin expression, and attenuate proteinuria in diabetic rats. The combined therapy of valsartan and MMF did not show any superiority over monotherapies on renal protection. MMF may have renoprotective effect in early stages of diabetic nephropathy through preventing podocytes loss and anti-inflammatory activity.

Molecular characterization of multidrug-resistant Klebsiella pneumoniae isolates.

Klebsiella pneumoniae is an important cause of healthcare-associated infections worldwide. Selective pressure, the extensive use of antibiotics, and the conjugational transmission of antibiotic resistance genes across bacterial species and genera facilitate the emergence of multidrug-resistant (MDR) K. pneumoniae. Here, we examined the occurrence, phenotypes and genetic features of MDR K. pneumoniae isolated from patients in intensive care units (ICUs) at the First Affiliated Hospital of Xiamen University in Xiamen, China, from January to December 2011. Thirty-eight MDR K. pneumoniae strains were collected. These MDR K. pneumoniae isolates possessed at least seven antibiotic resistance determinants, which contribute to the high-level resistance of these bacteria to aminoglycosides, macrolides, quinolones and ß-lactams. Among these isolates, 24 strains were extended-spectrum ß-lactamase (ESBL) producers, 2 strains were AmpC producers, and 12 strains were both ESBL and AmpC producers. The 38 MDR isolates also contained class I (28/38) and class II integrons (10/38). All 28 class I-positive isolates contained aacC1, aacC4, orfX, orfX' and aadA1 genes. ß-lactam resistance was conferred through bla SHV (22/38), bla TEM (10/38), and bla CTX-M (7/38). The highly conserved bla KPC-2 (37/38) and bla OXA-23(1/38) alleles were responsible for carbapenem resistance, and a gyrAsite mutation (27/38) and the plasmid-mediated qnrB gene (13/38) were responsible for quinolone resistance. Repetitive-sequence-based PCR (REP-PCR) fingerprinting of these MDR strains revealed the presence of five groups and sixteen patterns. The MDR strains from unrelated groups showed different drug resistance patterns; however, some homologous strains also showed different drug resistance profiles. Therefore, REP-PCR-based analyses can provide information to evaluate the epidemic status of nosocomial infection caused by MDR K. pneumoniae; however, this test lacks the power to discriminate some isolates. Thus, we propose that both genotyping and REP-PCR typing should be used to distinguish genetic groups beyond the species level.

Molecular characterization of multidrug-resistant Klebsiella pneumoniae isolates

Klebsiella pneumoniae is an important cause of healthcare-associated infections worldwide. Selective pressure, the extensive use of antibiotics, and the conjugational transmission of antibiotic resistance genes across bacterial species and genera facilitate the emergence of multidrug-resistant (MDR) K. pneumoniae. Here, we examined the occurrence, phenotypes and genetic features of MDR K. pneumoniae isolated from patients in intensive care units (ICUs) at the First Affiliated Hospital of Xiamen University in Xiamen, China, from January to December 2011. Thirty-eight MDR K. pneumoniae strains were collected. These MDR K. pneumoniae isolates possessed at least seven antibiotic resistance determinants, which contribute to the high-level resistance of these bacteria to aminoglycosides, macrolides, quinolones and β-lactams. Among these isolates, 24 strains were extended-spectrum β-lactamase (ESBL) producers, 2 strains were AmpC producers, and 12 strains were both ESBL and AmpC producers. The 38 MDR isolates also contained class I (28/38) and class II integrons (10/38). All 28 class I-positive isolates contained aacC1, aacC4, orfX, orfX’ and aadA1 genes. β-lactam resistance was conferred through bla_SHV (22/38), bla_TEM (10/38), and bla_CTX-M (7/38). The highly conserved bla_KPC-2 (37/38) and bla_OXA-23(1/38) alleles were responsible for carbapenem resistance, and a gyrAsite mutation (27/38) and the plasmid-mediated qnrB gene (13/38) were responsible for quinolone resistance. Repetitive-sequence-based PCR (REP-PCR) fingerprinting of these MDR strains revealed the presence of five groups and sixteen patterns. ...

Molecular characterization of multidrug-resistant Klebsiella pneumoniae isolates

Klebsiella pneumoniae is an important cause of healthcare-associated infections worldwide. Selective pressure, the extensive use of antibiotics, and the conjugational transmission of antibiotic resistance genes across bacterial species and genera facilitate the emergence of multidrug-resistant (MDR) K. pneumoniae. Here, we examined the occurrence, phenotypes and genetic features of MDR K. pneumoniae isolated from patients in intensive care units (ICUs) at the First Affiliated Hospital of Xiamen University in Xiamen, China, from January to December 2011. Thirty-eight MDR K. pneumoniae strains were collected. These MDR K. pneumoniae isolates possessed at least seven antibiotic resistance determinants, which contribute to the high-level resistance of these bacteria to aminoglycosides, macrolides, quinolones and β-lactams. Among these isolates, 24 strains were extended-spectrum β-lactamase (ESBL) producers, 2 strains were AmpC producers, and 12 strains were both ESBL and AmpC producers. The 38 MDR isolates also contained class I (28/38) and class II integrons (10/38). All 28 class I-positive isolates contained aacC1, aacC4, orfX, orfX’ and aadA1 genes. β-lactam resistance was conferred through blaSHV (22/38), blaTEM (10/38), and blaCTX-M (7/38). The highly conserved blaKPC-2 (37/38) and blaOXA-23(1/38) alleles were responsible for carbapenem resistance, and a gyrAsite mutation (27/38) and the plasmid-mediated qnrB gene (13/38) were responsible for quinolone resistance. Repetitive-sequence-based PCR (REP-PCR) fingerprinting of these MDR strains revealed the presence of five groups and sixteen patterns. ...