Nanoclay-Modified Hyaluronic Acid Microspheres for Bone Induction by Sustained rhBMP-2 Delivery.

Microspheres (MSs) are ideal candidates as biological scaffolds loading with growth factors or cells for bone tissue engineering to repair irregular alveolar bone defects by minimally invasive injection. However, the high initial burst release of growth factor and low cell attachment limit the application of microspheres. The modification of microspheres often needs expensive experiments facility or complex chemical reactions, which is difficult to achieve and may bring other problems. In this study, a sol-grade nanoclay, laponite XLS is used to modify the surface of MSs to enhance its affinity to either positively or negatively charged proteins and cells without changing the interior structure of the MSs. Recombinant human bone morphogenetic protein-2 (rhBMP-2) is used as a representation of growth factor to check the osteoinduction ability of laponite XLS-modified MSs. By modification, the protein sustained release, cell loading, and osteoinduction ability of MSs are improved. Modified by 1% laponite XLS, the MSs can not only promote osteogenic differentiation of MC3T3-E1 cells by themselves, but also enhance the effect of the rhBMP-2 below the effective dose. Collectively, the study provides an easy and viable method to modify the biological behavior of microspheres for bone tissue regeneration.

E3 ligase MG53 suppresses tumor growth by degrading cyclin D1.

Due to the essential role of cyclin D1 in regulating transition from G1 to S phase in cell cycle, aberrant cyclin D1 expression is a major oncogenic event in many types of cancers. In particular, the dysregulation of ubiquitination-dependent degradation of cyclin D1 contributes to not only the pathogenesis of malignancies but also the refractory to cancer treatment regiments with CDK4/6 inhibitors. Here we show that in colorectal and gastric cancer patients, MG53 is downregulated in more than 80% of tumors compared to the normal gastrointestinal tissues from the same patient, and the reduced MG53 expression is correlated with increased cyclin D1 abundance and inferior survival. Mechanistically, MG53 catalyzes the K48-linked ubiquitination and subsequent degradation of cyclin D1. Thus, increased expression of MG53 leads to cell cycle arrest at G1, and thereby markedly suppresses cancer cell proliferation in vitro as well as tumor growth in mice with xenograft tumors or AOM/DSS induced-colorectal cancer. Consistently, MG53 deficiency results in accumulation of cyclin D1 protein and accelerates cancer cell growth both in culture and in animal models. These findings define MG53 as a tumor suppressor via facilitating cyclin D1 degradation, highlighting the therapeutic potential of targeting MG53 in treating cancers with dysregulated cyclin D1 turnover.

Insulin reduces pyroptosis-induced inflammation by PDHA1 dephosphorylation-mediated NLRP3 activation during myocardial ischemia-reperfusion injury.

BACKGROUND: Previous studies proved that pyrin domain-containing protein 3 (NLRP3)-induced pyroptosis plays an important role in Myocardial ischemia-reperfusion injury (MIRI). Insulin can inhibit the activation of NLRP3 inflammasome, although the exact mechanism remains unclear. The aim of this study was to determine whether insulin reduces NLRP3-induced pyroptosis by regulating pyruvate dehydrogenase E1alpha subunit (PDHA1) dephosphorylation during MIRI. METHODS: Rat hearts were subject to 30 min global ischemia followed by 60 min reperfusion, with or without 0.5 IU/L insulin. Myocardial ischemia-reperfusion injury was evaluated by measuring myocardial enzymes release, Cardiac hemodynamics, pathological changes, infarct size, and apoptosis rate. Cardiac aerobic glycolysis was evaluated by measuring ATP, lactic acid content, and pyruvate dehydrogenase complex (PDHc) activity in myocardial tissue. Recombinant adenoviral vectors for PDHA1 knockdown were constructed. Pyroptosis-related proteins were measured by Western blotting analysis, immunohistochemistry staining, and ELISA assay, respectively. RESULTS: It was found that insulin significantly reduced the area of myocardial infarction, apoptosis rate, and improved cardiac hemodynamics, pathological changes, energy metabolism. Insulin inhibits pyroptosis-induced inflammation during MIRI. Subsequently, Adeno-associated virus was used to knock down cardiac PDHA1 expression. Knockdown PDHA1 not only promoted the expression of NLRP3 but also blocked the inhibitory effect of insulin on NLRP3-mediated pyroptosis in MIRI. CONCLUSIONS: Results suggest that insulin protects against MIRI by regulating PDHA1 dephosphorylation, its mechanism is not only to improve myocardial energy metabolism but also to reduce the NLRP3-induced pyroptosis.

MG53 E3 Ligase-Dead Mutant Protects Diabetic Hearts From Acute Ischemic/Reperfusion Injury and Ameliorates Diet-Induced Cardiometabolic Damage.

Cardiometabolic diseases, including diabetes and its cardiovascular complications, are the global leading causes of death, highlighting a major unmet medical need. Over the past decade, mitsugumin 53 (MG53), also called TRIM72, has emerged as a powerful agent for myocardial membrane repair and cardioprotection, but its therapeutic value is complicated by its E3 ligase activity, which mediates metabolic disorders. Here, we show that an E3 ligase-dead mutant, MG53-C14A, retains its cardioprotective function without causing metabolic adverse effects. When administered in normal animals, both the recombinant human wild-type MG53 protein (rhMG53-WT) and its E3 ligase-dead mutant (rhMG53-C14A) protected the heart equally from myocardial infarction and ischemia/reperfusion (I/R) injury. However, in diabetic db/db mice, rhMG53-WT treatment markedly aggravated hyperglycemia, cardiac I/R injury, and mortality, whereas acute and chronic treatment with rhMG53-C14A still effectively ameliorated I/R-induced myocardial injury and mortality or diabetic cardiomyopathy, respectively, without metabolic adverse effects. Furthermore, knock-in of MG53-C14A protected the mice from high-fat diet-induced metabolic disorders and cardiac damage. Thus, the E3 ligase-dead mutant MG53-C14A not only protects the heart from acute myocardial injury but also counteracts metabolic stress, providing a potentially important therapy for the treatment of acute myocardial injury in metabolic disorders, including diabetes and obesity.

Cardiac Ischemic Preconditioning Promotes MG53 Secretion Through H2O2-Activated Protein Kinase C-δ Signaling.

BACKGROUND: Ischemic heart disease is the leading cause of morbidity and mortality worldwide. Ischemic preconditioning (IPC) is the most powerful intrinsic protection against cardiac ischemia/reperfusion injury. Previous studies have shown that a multifunctional TRIM family protein, MG53 (mitsugumin 53; also called TRIM72), not only plays an essential role in IPC-mediated cardioprotection against ischemia/reperfusion injury but also ameliorates mechanical damage. In addition to its intracellular actions, as a myokine/cardiokine, MG53 can be secreted from the heart and skeletal muscle in response to metabolic stress. However, it is unknown whether IPC-mediated cardioprotection is causally related to MG53 secretion and, if so, what the underlying mechanism is. METHODS: Using proteomic analysis in conjunction with genetic and pharmacological approaches, we examined MG53 secretion in response to IPC and explored the underlying mechanism using rodents in in vivo, isolated perfused hearts, and cultured neonatal rat ventricular cardiomyocytes. Moreover, using recombinant MG53 proteins, we investigated the potential biological function of secreted MG53 in the context of IPC and ischemia/reperfusion injury. RESULTS: We found that IPC triggered robust MG53 secretion in rodents in vivo, perfused hearts, and cultured cardiac myocytes without causing cell membrane leakage. Mechanistically, IPC promoted MG53 secretion through H2O2-evoked activation of protein kinase-C-δ. Specifically, IPC-induced myocardial MG53 secretion was mediated by H2O2-triggered phosphorylation of protein kinase-C-δ at Y311, which is necessary and sufficient to facilitate MG53 secretion. Functionally, systemic delivery of recombinant MG53 proteins to mimic elevated circulating MG53 not only restored IPC function in MG53-deficient mice but also protected rodent hearts from ischemia/reperfusion injury even in the absence of IPC. Moreover, oxidative stress by H2O2 augmented MG53 secretion, and MG53 knockdown exacerbated H2O2-induced cell injury in human embryonic stem cell-derived cardiomyocytes, despite relatively low basal expression of MG53 in human heart. CONCLUSIONS: We conclude that IPC and oxidative stress can trigger MG53 secretion from the heart via an H2O2-protein kinase-C-δ-dependent mechanism and that extracellular MG53 can participate in IPC protection against cardiac ischemia/reperfusion injury.

PHLPP2 is regulated by competing endogenous RNA network in pathogenesis of colon cancer.

Recently, homologous pleckstrin-homology (PH)-domain leucine-rich-repeat protein phosphatases (PHLPP2) has been reported as a tumor suppressor in colon cancer. This study aimed to unravel the possible involvement of long noncoding RNAs (lncRNAs) and microRNAs (miRNAs) regulating PHLPP2 in colon cancer. Expressions of candidate lncRNAs and miRNAs were verified by the RT-qPCR and Western blot analyses in colon cancer. The roles of candidate genes in colon cancer were investigated in HT-29 cells in vitro and in mouse tumor xenograft model in vivo. PHLPP2, a target of miR-141 and miR-424, was downregulated in colon cancer. PHLPP2 upregulation and miR-141 and miR-424 downregulation suppressed the colon cancer cell proliferation, migration, invasion, and epithelial-mesenchymal transition, and promote cell apoptosis, which also resulted in suppression of tumor metastasis and formation. Furthermore, LINC00402, LINC00461, and SFTA1P were identified as the targets of miR-141 and miR-424 and acted as competitive endogenous RNAs (ceRNAs) of PHLPP2. The upregulation of LINC00402, LINC00461, and SFTA1P was verified to enhance the suppressive effects of PHLPP2 in the pathogenesis of colon cancer. Conjointly, our results demonstrated the suppressive effects of PHLPP2 in colon cancer and proved that LINC00402, LINC00461, and SFTA1P acted as ceRNAs of PHLPP2 by competitive binding to miR-141 and miR-424.

[Role of protein kinase D1 in regulating the growth, apoptosis and drug sensitivity of oral squamous carcinoma cells].

OBJECTIVE: This study aimed to investigate the role of protein kinase D (PKD)1 in regulating the growth, apop-tosis, and drug sensitivity of the squamous carcinoma cell line SCC-25. METHODS: The SCC-25 cell line was transfected with either the control-shRNA or PKD1-shRNA plasmids. The stable transfected cells were selected, and the efficiency of PKD1 knockdown was detected by Western blot. The growth and apoptosis of SCC-25 were analyzed with a cell counting kit-8 (CCK8) and flow cytometry. The 50% inhibitory concentrations (IC50) of paclitaxel in the control and PKD1 knockdown cell lines were detected by CCK-8. The expression levels of Bax, Bcl-2, and P-gp were detected by Western blot. RESULTS: PKD1 was constitutively expressed and phosphorylated in various cancer cell lines. Inhibiting the expression of PKD1 in SCC-25 cells by RNA interference could inhibit the growth and promote the apoptosis of SCC-25 cells via downregulating Bcl-2 expression. Additionally, inhibiting PKD1 expression could downregulate the expression of P-gp, thereby decreasing both the IC50 and resistance index of paclitaxel. CONCLUSIONS: PKD1 plays an important role in regulating the biobehavior of SCC-25. It is a potential therapeutic target for oral squamous carcinoma.

Glucose-Sensitive Myokine/Cardiokine MG53 Regulates Systemic Insulin Response and Metabolic Homeostasis.

BACKGROUND: Mitsugumin 53 (MG53 or TRIM72), a striated muscle-specific E3 ligase, promotes ubiquitin-dependent degradation of the insulin receptor and insulin receptor substrate-1 and subsequently induces insulin resistance, resulting in metabolic syndrome and type 2 diabetes mellitus (T2DM). However, it is unknown how MG53 from muscle regulates systemic insulin response and energy metabolism. Increasing evidence demonstrates that muscle secretes proteins as myokines or cardiokines that regulate systemic metabolic processes. We hypothesize that MG53 may act as a myokine/cardiokine, contributing to interorgan regulation of insulin sensitivity and metabolic homeostasis. METHODS: Using perfused rodent hearts or skeletal muscle, we investigated whether high glucose, high insulin, or their combination (conditions mimicking metabolic syndrome or T2DM) alters MG53 protein concentration in the perfusate. We also measured serum MG53 levels in rodents and humans in the presence or absence of metabolic diseases, particularly T2DM. The effects of circulating MG53 on multiorgan insulin response were evaluated by systemic delivery of recombinant MG53 protein to mice. Furthermore, the potential involvement of circulating MG53 in the pathogenesis of T2DM was assessed by neutralizing blood MG53 with monoclonal antibodies in diabetic db/db mice. Finally, to delineate the mechanism underlying the action of extracellular MG53 on insulin signaling, we analyzed the potential interaction of MG53 with extracellular domain of insulin receptor using coimmunoprecipitation and surface plasmon resonance assays. RESULTS: Here, we demonstrate that MG53 is a glucose-sensitive myokine/cardiokine that governs the interorgan regulation of insulin sensitivity. First, high glucose or high insulin induces MG53 secretion from isolated rodent hearts and skeletal muscle. Second, hyperglycemia is accompanied by increased circulating MG53 in humans and rodents with diabetes mellitus. Third, systemic delivery of recombinant MG53 or cardiac-specific overexpression of MG53 causes systemic insulin resistance and metabolic syndrome in mice, whereas neutralizing circulating MG53 with monoclonal antibodies has therapeutic effects in T2DM db/db mice. Mechanistically, MG53 binds to the extracellular domain of the insulin receptor and acts as an allosteric blocker. CONCLUSIONS: Thus, MG53 has dual actions as a myokine/cardiokine and an E3 ligase, synergistically inhibiting the insulin signaling pathway. Targeting circulating MG53 opens a new therapeutic avenue for T2DM and its complications.

Effects of nicotine on the metabolism and gene expression profile of Sprague­Dawley rat primary osteoblasts.

Smoking is a risk factor associated with bone and oral diseases, particularly periodontitis. Nicotine, the major toxic component of tobacco, is able to affect the quality and quantity of bone. Osteoblasts serve an important role in bone formation. Thus far, the effects of nicotine on metabolism­associated gene and protein expression in osteoblasts have been controversial and the mechanisms remain unclear. The present study assessed alterations in osteogenic activity by performing a Cell Counting kit­8 assay to investigate proliferation, Annexin V­fluorescein isothiocyanate/propidium iodide staining to investigate apoptosis, alizarin red staining to investigate the formation of mineralized nodules, reverse transcription­quantitative polymerase chain reaction and western blotting to investigate the mRNA and protein levels of collagen I, alkaline phosphatase, bone osteocalcin, bone sialoprotein and osteopontin; and mRNA microarray expression analysis, Kyoto Encyclopedia of Genes and Genomes and Gene Ontology analysis to investigate the whole genome expression profile of Sprague­Dawley (SD) rat primary osteoblasts following treatment with different concentrations of nicotine. The results demonstrated that nicotine inhibited proliferation, promoted early apoptosis and inhibited mineralized nodule formation in a dose­dependent manner by regulating alkaline phosphatase activity and the expression of osteoblast metabolism­associated genes and proteins. According to microarray analysis, several genes associated with bone metabolism and genes in the Hedgehog and Notch signaling pathways were downregulated significantly in nicotine­treated osteoblasts. The results of the present study indicated that nicotine may serve an inhibitory, dose­dependent role in SD rat primary osteoblasts that may be caused by the perturbation of genes and signaling pathways associated with bone formation. These results may provide a theoretical basis for future research regarding bone metabolism and targeted treatment of oral diseases associated with smoking.

Spalt-like transcription factor 4 as a potential diagnostic and prognostic marker of colorectal cancer.

OBJECTIVE: The study aimed to investigate the role of spalt-like transcription factor 4 (SALL4) in the diagnosis and prognosis of colorectal cancer (CRC). METHODS: Between May 2008 and January 2010, 135 patients with CRC were recruited and subsequently assigned into the case group of the study. Additionally, 140 healthy individuals under identical conditions were selected as the control group. Venous blood was collected from all subjects. High expression of SALL4 was detected by immunohistochemistry, and SALL4 serum levels were detected using ELISA. A 5-year follow-up was conducted. A Kaplan-Meier curve was applied for analysis of survival rates, and a log-rank was used for univariate analysis. RESULTS: The case group exhibited largely positive expression levels of SALL4. Levels of SALL4 serum were much higher than those in the control group. The AUC value of CRC detected by serum SALL4 was 0.916 (95% CI was 0.881-0.951), which regarded 0.1255 µcg/l to be the point of critical value. This result was in direct relation to data from the receiver operating characteristic curve (ROC). The sensitivity and specificity of serum SALL4 levels in the diagnosis of CRC were 85.9% and 85.7%, respectively. The AUC value of CRC detected by tissue SALL4 was 0.727 (95% CI was 0.666-0.789), 0.5 was regarded as the critical value. The sensitivity and specificity of SALL4 expression in CRC tissues regarding the diagnosis of CRC was determined to be 58.6% and 86.9% respectively. The levels of SALL4 expression in serum and tissues highlighted a correlation to lymph node metastasis (LNM), differentiation degree, Dukes staging and tumor node metastasis staging. Lower serum SALL4 levels were associated with higher survival rates in CRC patients. In accordance with a COX regression, LNM, differentiation degree and SALL4 levels were determined as being prognostic factors in patients with CRC (both P< 0.05). CONCLUSION: Our experimental data indicated that over expression of SALL4 was found in CRC and low expression of SALL4 was connected with high survival rate after surgery. Thus our study suggested that SALL4 could serve as a potential diagnostic and prognostic marker of CRC.

MG53: Biological Function and Potential as a Therapeutic Target.

MG53 (also known as tripartite motif, TRIM72) is a cardiac and skeletal muscle-specific TRIM-family protein that exhibits multiple biologic functions. First, MG53 participates in plasma membrane repair of the heart, skeletal muscle, and, other tissues. Second, MG53 is essentially involved in the cardioprotection of cardiac ischemic, preconditioning, and postconditioning by activating the PI3K-Akt-GSK3ß and ERK1/2 survival signaling pathways. Moreover, systemic delivery of recombinant MG53 protein ameliorates the impact of a range of injury insults on the heart, skeletal muscle, lung, kidney, skin, and brain. It is noteworthy that chronic upregulation of MG53 induces insulin resistance and metabolic diseases, such as type 2 diabetes and its cardiovascular complications, by acting as an E3 ligase to mediate the degradation of insulin receptor and insulin receptor substrate-1. In addition, MG53 negatively regulates myogenesis. In summary, MG53 is a multifunctional protein involved in the vital physiologic and pathologic processes of multiple organs and is a promising therapeutic target for various human diseases. In this review, we comprehensively summarize current research progress on the biologic functions and therapeutic potential of MG53.

MG53 is a double-edged sword for human diseases.

Mitsugumin 53 (MG53), also named Trim72, is a multi-functional TRIM-family protein, which is abundantly expressed in cardiac and skeletal muscle. It has been shown that MG53 not only plays important physiological roles but also acts as a crucial pathogenic factor of various diseases. First, MG53 preserves cardiac and skeletal muscle integrity via facilitating plasma membrane repair. Second, MG53 is essentially involved in cardiac ischemic preconditioning and postconditioning by activating PI3K-Akt-GSK3ß and ERK1/2 cell survival signaling pathways. Moreover, systemic delivery of recombinant MG53 is able to abolish mechanic or ischemia-reperfusion (I/R)-induced injury of multiple organs, including heart, skeletal muscle, lung, kidney and skin. Importantly, MG53 acts as an E3 ligase to mediate the degradation of insulin receptor and insulin receptor substrate-1, and subsequently induces insulin resistance and metabolic diseases such as type-2 diabetes and its cardiovascular complications. In addition, MG53 negatively regulates myogenesis. As a potential therapeutic target of human diseases, multiple facets of MG53 biological function and mechanisms of action should be taken into the consideration to maximize its beneficial effects and minimize potential side-effects. Here in this review, we intend to comprehensively summarize the current progresses on the biological functions of MG53, focusing on its clinical value as a therapeutic target.

[T2 mapping and knee thickness measurement in healthy young adults using quantitative 3.0T magnetic resonance imaging].

OBJECTIVE: To investigate the T2 values and knee thickness in healthy young adults using 3.0 T magnetic resonance imaging(MRI) . METHODS: Totally 40 volunteers(18-30 years old) with body mass index between 18.5-24.0 kg/m(2) were divided into two groups(22 men and 18 women) according to their gender. Also in addition, each group was divided into two subgroups(right knee and left knee) . The T2 values and the thickness of the areas on the medial condyle of femur, the lateral condyle of femur, the medial tibial plateau, the lateral tibial plateau, and the patella of the knee cartilage were measured. RESULTS: The T2 values and the thickness of the right and left knee cartilages showed no significant differences between men and women (P>0.05) . Also, the T2 values in the five parts of the knee cartilage also were not significantly different between men and women (P>0.05) . However, the thickness of the 5 parts of the knee cartilage significantly differed between men and women(P<0.05) . CONCLUSIONS: The thickness of the knee cartilage may different between male and female young adults. The T2 values of the cartilage may be not affected by the gender.

Central role of E3 ubiquitin ligase MG53 in insulin resistance and metabolic disorders.

Insulin resistance is a fundamental pathogenic factor present in various metabolic disorders including obesity and type 2 diabetes. Although skeletal muscle accounts for 70-90% of insulin-stimulated glucose disposal, the mechanism underlying muscle insulin resistance is poorly understood. Here we show in mice that muscle-specific mitsugumin 53 (MG53; also called TRIM72) mediates the degradation of the insulin receptor and insulin receptor substrate 1 (IRS1), and when upregulated, causes metabolic syndrome featuring insulin resistance, obesity, hypertension and dyslipidaemia. MG53 expression is markedly elevated in models of insulin resistance, and MG53 overexpression suffices to trigger muscle insulin resistance and metabolic syndrome sequentially. Conversely, ablation of MG53 prevents diet-induced metabolic syndrome by preserving the insulin receptor, IRS1 and insulin signalling integrity. Mechanistically, MG53 acts as an E3 ligase targeting the insulin receptor and IRS1 for ubiquitin-dependent degradation, comprising a central mechanism controlling insulin signal strength in skeletal muscle. These findings define MG53 as a novel therapeutic target for treating metabolic disorders and associated cardiovascular complications.

[Effect of silver-hydroxyapatite/titania nanocomposites on proliferation, vitality and ultrastructure of osteoblasts].

OBJECTIVE: Osteoblasts behaviors were investigated when cultured in the presence of silver-hydroxyapatite/titania nanoparticles (nAg-HA/TiO2) in vitro. METHODS: Rat calvaria osteoblasts were cultured in the presence of 10 mirog/mL-500 mirog/mL nHA or nAg-HA/TiO2 for 2 h, 6 h, 8 h, 24 h, 72 h and 120 h. Cell proliferation, vitality and ultrastructure were tested using cell counting chamber, MTT assay, and transmission electron microscope (TEM). RESULTS: Both cell proliferation and vitality were restricted by addition of nanoparticles, while the respiration rates as an index for unit cell viability were enhanced. nAg-HA/TiO2 at low concentration showed superiority. No remarkable ultrastructural changes were observed in the osteoblasts exposed to nanoparticles. The differences in cell proliferation and cell vitality between nAg-HA/TiO2 group and nHA group at the same concentration were insignificant. CONCLUSION: nAg-HA/TiO2 restricted cells proliferation, but triggered unit cell viability. Cytocompatibility of nAg-HA/TiO2 is almost the same as that of nHA's.

[Prokaryotic expression and polyclonal antibody preparation of truncated duck hepatitis B virus core protein].

AIM: To construct a prokaryotic plasmid expressing truncated duck hepatitis B virus core protein (DHBc(1-214)), purify the recombinant protein, and to develop polyclonal antibodies against DHBc. METHODS: DHBc(1-214) was cloned into vector pRSET-B, then expressed in E.coli Rosetta(DE3) pLacI induced by IPTG. The recombinant protein was purified using Ni-NTA spin column. Polyclonal antibody was developed by immunizing BALB/c mice with the purified recombinant protein, and their sensitivity and specificity were tested using enzyme-linked immunosorbent assay, immunohistochemical staining and Western blot analysis. RESULTS: Recombinant plasmid expressing truncated DHBc(1-214) was successfully constructed. A protein of 28,000 was expressed and purified. Polyclonal serum antibody with a high specificity was obtained by immunizing BALB/c mice with the purified recombinant protein. CONCLUSION: The truncated recombinant DHBc(1-214) developed in this study is purified and shown strong antigenecity. The polyclonal antibody against DHBc protein is generated by regular immunization method, demonstrating both high sensitivity and specificity. The protein and the antibody can be used for further clinical examination and research of DHBV.

[Comparative study of shaping ability between rotary ProTaper and Flexofile].

OBJECTIVE: To compare the shaping ability of rotary ProTaper and Flexofile in simulated resin root canals. METHODS: Forty simulated resin root canals were randomly assigned to two groups, one group for rotary ProTaper with crown-down technique and the other for Flexofile with balanced force technique. Change of working length and incidence of canal aberration and instruments failure were recorded. After preparation, the change of root canal curvature and the amount of resin removed at the inner and outer canal walls were measured with Image Pro Plus 5.0. The centring ability and total amount of resin removed were also assessed. RESULTS: In the model of simulated resin canals, ProTaper instruments maintained working length better. Canals prepared with ProTaper instruments remained better curvature and showed fewer aberration compared with those prepared with Flexofile (P < 0.01). ProTaper instruments performed a better centring ability. CONCLUSION: ProTaper instruments have a better shaping ability in simulated resin root canals.

Evaluation of bilateral cingulum with tractography in patients with Alzheimer's disease.

A fiber-tracking algorithm was used to extract fractional anisotropy of bilateral cingulum bundles in patients with probable Alzheimer's disease and normal aging controls. In addition, their hippocampal volumes were measured manually. Relative to normal controls, Alzheimer's disease patients showed a significant reduction of fractional anisotropy and hippocampal volumes. Significant correlation was observed between fractional anisotropy values and volumes of hippocampi and mini-mental state examination scores. This study suggests that lower anisotropy of cingulum bundles is associated with cognitive dysfunction and atrophy of the limbic system.

Effects of cecropin-XJ on growth and adherence of oral cariogenic bacteria in vitro.

BACKGROUND: Cecropin-XJ belongs to cecropin-B, which is the most potent antibacterial peptide found naturally. The aim of this study was to investigate the effects of cecropin-XJ on growth and adherence of oral cariogenic bacteria. METHODS: Four oral cariogenic bacteria (Streptococcus mutans, Lactobacillus acidophilus, Actinomyces viscosus and Actinomyces naeslundii) were chosen for this experiment. The minimal inhibitory concentrations (MICs) and reductive percent of bacterial growth were used to assay the antibacterial activity of cecropin-XJ. Mammalian cytotoxicity of cecropin-XJ was tested with human periodontal membrane fibroblasts by tetrazolium (MTT) colorimetric assay. The bacterial morphological changes induced by cecropin-XJ were examined on scanning electron microscope (SEM). The influence of cecropin-XJ on bacterial adhesion to saliva-coated hydroxyapatite (S-HA) was measured by scintillation counting. RESULTS: The MICs of cecropin-XJ for inhibition of the growth of four bacteria ranged from 4.0 to 42.8 micromol/L with the highest susceptible to A. naeslundii and the lowest susceptible to L. acidophilus. At pH 6.8, 5.5 and 8.2, 1/2 MIC of cecropin-XJ reduced the number of viable bacteria by 40.9%, 67.8% and 32.8% for S. mutans and by 28.1%, 57.2% and 37.9% for L. acidophilus. The activities against S. mutans and L. acidophilus increased at pH 5.5 compared with pH 6.8 (P < 0.01, respectively). In present of 50% saliva, 1/2 MIC of the peptide decreased the direct count of viable cells by 29.2% and 14.4% for S. mutans and L. acidophilus, respectively (P < 0.01 and P > 0.05, respectively), whereas almost no reduction counts were detected in the presence of 20% serum for both bacteria (P > 0.05, respectively). Mammalian cytotoxicity of cecropin-XJ from 1.0 to 100 micromol/L exhibited no cytotoxicity against human periodontal membrane fibroblasts (P > 0.05). Bacterial morphological changes induced by MIC of cecropin-XJ examined on SEM showed cell surface disruption. Furthermore, the ability of A. naeslundii adhesion to S-HA decreased significantly with MIC of cecropin-XJ for 10 and 20 minutes (P = 0.001 and 0.000, respectively), and S. mutans, A. viscosus to S-HA decreased significantly with MIC of cecropin-XJ for 20 minutes (P = 0.000, respectively). CONCLUSIONS: Cecropin-XJ exhibited bactericidal action against cariogenic pathogens, and the antibacterial activity enhanced in the acid environment. The results also demonstrate that cecropin-XJ prevents S. mutans and actinomyces adsorption to S-HA. These findings suggest that Cecropin-XJ may have potential to prevent caries.