Wnt5a promotes differentiation of human dental papilla cells

AIM

To investigate the role of Wnt5a in the process of differentiation of human dental papilla cells (HDPCs).

METHODOLOGY

Recombinant adenovirus encoding full-length Wnt5a cDNA was constructed to investigate the biological role of Wnt5a on the differentiation of HDPCs. The effect of Wnt5a on HDPCs differentiation was determined by ALP activity assay, ALP staining and mineral induction assay. Mineralization-related gene expressions were assessed by RT-PCR.

RESULTS

Immunostaining revealed Wnt5a expression in the odontoblast layer and dental papilla tissue. Over-expression of Wnt5a by transfecting HDPCs with an Wnt5a-carrying construct increased ALPase activity and the formation of mineralized nodules of HDPCs. RT-PCR analysis showed that the expressions of mineralization-related genes, such as bone sialoprotein, collagen type I, osteonectin, osteopontin (OCN), dentine matrix protein-1 were up-regulated by Wnt5a.

CONCLUSIONS

Wnt5a promoted differentiation of HDPCs.

Effects of adenoviral-mediated coexpression of bone morphogenetic protein-7 and insulin-like growth factor-1 on human periodontal ligament cells

BACKGROUND AND OBJECTIVE

Bone morphogenetic protein-7 (BMP-7) and insulin-like growth factor-1 (IGF-1) are important in periodontal reconstruction. However, their synergistic effect in periodontal regeneration by gene delivery has not been reported. In this study, gene delivery of these two growth factors to human periodontal ligament cells (hPDLCs) was examined for its effects on cell proliferation and differentiation.

MATERIAL AND METHODS

Recombinant adenoviruses containing both human BMP-7 and IGF-1 cDNA created by introducing the internal ribosome entry site (IRES) sequence were used to transfer the genes into hPDLCs. 3-(4,5-Dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay and cell cycle analysis were used to observe their effects on cell proliferation, while alkaline phosphatase activity measurement, RT-PCR and in vivo tests were conducted to investigate their effects on cell differentiation.

RESULTS

The proliferation of hPDLCs transduced by adenoviruses coexpressing BMP-7 and IGF-1 was suppressed while their differentiation ability was enhanced. There was a synergism of BMP-7 and IGF-1 in up-regulating alkaline phosphatase activity and mRNA levels of collagen type I and Runx2. Implantation in vivo with scaffolds illustrated that the transduced cells exhibited osteogenic differentiation and formed bone-like structures.

CONCLUSION

The combined delivery of BMP-7 and IGF-1 genes using an IRES-based strategy synergistically enhanced differentiation of hPDLCs. It is suggested that this could be a new potential method in gene therapy for periodontal reconstruction.

PHF10 is required for cell proliferation in normal and SV40-immortalized human fibroblast cells

Normal human diploid fibroblasts have limited life span in culture and undergo replicative senescence after 50-60 population doublings. On the contrary, cancer cells typically divide indefinitely and are immortal. Expression of SV40 large T and small t antigens in human fibroblasts transiently extends their life span by 20-30 population doublings and facilitates immortalization. We have identified a rearrangement in chromosome 6 shared by SV40-transformed human fibroblasts. Rearrangements involving chromosome 6 are among the most frequent in human carcinogenesis. In this paper, we extend analysis of the 6q26-q27 region, a putative site for a growth suppressor gene designated SEN6 involved in immortalization of SV40-transformed cells. Detailed molecular characterization of the rearranged chromosomes (6q*, normal appearing; and 6q(t), translocated) in the SV40-immortalized cell line HALneo by isolating each of these 2 chromosomes in mouse/HAL somatic cell hybrids is presented. Analysis of these mouse/HAL somatic cell hybrids with polymorphic and nonpolymorphic markers revealed that the 6q* has undergone a chromosomal break in the MLLT4 gene (alias AF6). This result in conjunction with previous published observations leads us to conclude that SEN6 lies between MLLT4 and TBP at chromosomal region 6q27. Examination of different genes (MLLT4, DLL1, FAM120B, PHF10) located within this interval that are expressed in HS74 normal fibroblast cells reveals that overexpression of epitope-tagged truncated PHF10 cDNAs resulted in reduced cell proliferation in multiple cell lines. Paradoxically, down-regulation of PHF10 by RNAi also resulted in loss of cell proliferation in normal fibroblast cells, indicating PHF10 function is required for cell growth. Taken together, these observations suggest that decreased cell proliferation with epitope-tagged truncated PHF10 proteins may be due to dominant negative effects or due to unregulated expression of these mutant proteins. Hence we conclude that PHF10 is not SEN6 but is required for cell growth.

A global sensitivity test for evaluating statistical hypotheses with nonidentifiable models

We consider the problem of evaluating a statistical hypothesis when some model characteristics are nonidentifiable from observed data. Such a scenario is common in meta-analysis for assessing publication bias and in longitudinal studies for evaluating a covariate effect when dropouts are likely to be nonignorable. One possible approach to this problem is to fix a minimal set of sensitivity parameters conditional upon which hypothesized parameters are identifiable. Here, we extend this idea and show how to evaluate the hypothesis of interest using an infimum statistic over the whole support of the sensitivity parameter. We characterize the limiting distribution of the statistic as a process in the sensitivity parameter, which involves a careful theoretical analysis of its behavior under model misspecification. In practice, we suggest a nonparametric bootstrap procedure to implement this infimum test as well as to construct confidence bands for simultaneous pointwise tests across all values of the sensitivity parameter, adjusting for multiple testing. The methodology's practical utility is illustrated in an analysis of a longitudinal psychiatric study.

Osteopontin induces angiogenesis through activation of PI3K/AKT and ERK1/2 in endothelial cells

Angiogenesis is a key step in tumor growth and metastasis. The mechanism by which osteopontin (OPN) induces the angiogenesis of endothelial cells remains unclear. Here, we show that OPN confers cytoprotection through the activation of the PI3K/Akt pathway with subsequent upregulation of Bcl-xL and activation of nuclear factor-kappaB. OPN enhances the expression of vascular endothelial growth factor (VEGF) through the phosphorylation of AKT and extracellular signal-regulated kinase (ERK). In turn, OPN-induced VEGF activates PI3K/AKT and the ERK1/2 pathway as a positive feedback signal. Blocking the feedback signal by anti-VEGF antibody, PI3-kinase inhibitor or ERK inhibitor can partially inhibit the OPN-induced human umbilical vein endothelial cell (HUVEC) motility, proliferation and tube formation, while blocking the signal by anti-OPN or anti-alphavbeta3 antibody completely abrogates the biological effects of OPN on HUVECs. In addition, blood vessel formation is also investigated in vivo. The antiangiogenesis efficacy of anti-OPN antibody in vivo is more effective than that of anti-VEGF antibody, which only blocks the feedback signals. These data show that OPN enhances angiogenesis directly through PI3K/AKT- and ERK-mediated pathways with VEGF acting as a positive feedback signal. The results suggest that OPN might be a valuable target for developing novel antiangiogenesis therapy for treatment of cancer.

Neoadjuvant chemoradiotherapy for locally advanced low-lying rectal cancer

e15095

Objective: The aim of this trial was to explore the possibility of further improvement of efficacy in neoadjuvant chemoradiation for the treatment of locally advanced low-lying rectal cancer and the management of patients with clinical complete regression. Methods: 192 cases with locally advanced low-lying rectal cancer (T3/T4 or N+) received preoperative radiotherapy comprising 40–46 Gy/20–23 fractions and concomitant oral capecitabine 625 mg/m2 bid for 10 weeks prior to surgery. Curative resection with TME was carried out 6 weeks after the end of radiation. Results: Patients (pts) were recruited from May 2001 through August 2007. Overall, 117 pts (60.9%) experienced adverse events but only 2 suffered from grade 3 hand-foot syndrome. 17 pts (8.9%) had clinical complete tumor regression without surgery, 175 pts underwent curative resection including of 134 pts with low anterior resection (LAR), 32 pts with ultra-low anterior resection with Parks’ coloanal anastomosis and among them 6 pts with diverting temporary colostomy and 9 pts with APR. Sphincter preservation was achieved in 95.3%. Pathologically, 24 pts (12.5%) showed CR together with 17 pts with clinical CR; the overall CR rate was 21.4%. According to the pathological staging: T0N0 41 cases, T2N0 43 cases, T3N0 77 cases, T4N0 5 cases, T2N1 11 cases, T3N1 13 cases, T4N0 5 cases, and T4N1 2 cases; in semiquantitative Dworak's tumor regression grade, TRG0 8 pts,TRG1 32, TRG2 28,TRG3 83 and TRG4 41 with an overall tumor downstaging of 79.2%. There were no operative deaths, 5 pts suffered from rectovaginal fistulas and 4 anastomotic leakages with an overall anastomotic leakage rate of 5.1% (9/175) and all recovered without further events. All patients have been followed up for a median of 46 months (range 12–87). During the time, 11 pts had lung metastases, 6 liver metastases and 7 had local recurrences. The 3-year disease-free survival was 86.6% and overall survival was 92.6%. Conclusions: Neoadjuvant chemoradiotherapy has high efficacy resulting in tumor down-staging, increased resectability and sphincter preservation, and a reduction in local recurrences. Meanwhile those patients with clinical complete response can be followed up closely and safely without surgery.

No significant financial relationships to disclose.

Characterization of the germination of Bacillus megaterium spores lacking enzymes that degrade the spore cortex

AIMS

To determine roles of cortex lytic enzymes (CLEs) in Bacillus megaterium spore germination.

METHODS AND RESULTS

Genes for B. megaterium CLEs CwlJ and SleB were inactivated and effects of loss of one or both on germination were assessed. Loss of CwlJ or SleB did not prevent completion of germination with agents that activate the spore's germinant receptors, but loss of CwlJ slowed the release of dipicolinic acid (DPA). Loss of both CLEs also did not prevent release of DPA and glutamate during germination with KBr. However, cwlJ sleB spores had decreased viability, and could not complete germination. Loss of CwlJ eliminated spore germination with Ca2+ chelated to DPA (Ca-DPA), but loss of CwlJ and SleB did not affect DPA release in dodecylamine germination.

CONCLUSIONS

CwlJ and SleB play redundant roles in cortex degradation during B. megaterium spore germination, and CwlJ accelerates DPA release and is essential for Ca-DPA germination. The roles of these CLEs are similar in germination of B. megaterium and Bacillus subtilis spores.

SIGNIFICANCE AND IMPACT OF THE STUDY

These results indicate that redundant roles of CwlJ and SleB in cortex degradation during germination are similar in spores of Bacillus species; consequently, inhibition of these enzymes will prevent germination of Bacillus spores.

Alendronate is effective to treat bone loss in renal transplantation recipients

Bone loss is a common complication among renal transplant patients. Some studies have shown that alendronate may be effective to treat bone loss in these patients. In this study, we have reported our experience with administration of alendronate to treat bone loss in renal transplanted patients.

METHODS

The 46 kidney transplant recipients with bone loss were randomly divided into 2 groups: group I was treated with calcium and calcitriol, and group II with calcium, calcitriol, and alendronate. We examined bone mineral density (BMD) and biochemical indicators of both groups. All patients received cyclosporine and prednisone treatment.

RESULTS

There was no significant difference in age, body mass index, gender, immunosuppression, time since transplantation, 25(OH)D(3), or intact parathyroid hormone levels at study commencement. The BMD of the femoral neck was significantly increased (P < .05), and the serum type I collagen-cross-linked N telopeptide (NTx) dramatically (P < .05) decreased in posttransplantation group II recipients treated with calcium, calcitriol, and alendronate. There were also significant differences in BMD and serum NTx between recipients treated with versus without alendronate (P < .05).

CONCLUSION

At least in the short term, alendronate is a effective inhibitor for the treatment of bone loss in renal transplantation patients.

The effects of the spatial influence function on orthotropic femur remodelling

The morphology and internal structure of bone are modulated by the mechanical stimulus. The osteocytes can sense the stimulus signals from the adjacent regions and respond to them through bone growth or bone absorption. This mechanism can be modelled as the spatial influence function (SIF) in bone adaptation algorithm. In this paper, the remodelling process was simulated in human femurs using an adaptation algorithm with and without SIF, and the trabecular bone was assumed to be orthotropic. A different influence radius and weighting factor were adopted to study the effects of the SIF on the bone density distribution and trabecular alignment. The results have shown that the mean density and L—T ratio (the ratio of longitudinal modulus to transverse modulus) had an excellent linear relationship with the weighting factor when the influence radius was small. The characteristics of density distribution and L—T ratio accorded with the actual observation or measurement when a small weighting factor was used. The large influence radius and weighting factor led to unrealistic results. In contrast, the SIF hardly affected the trabecular alignment, as the mean variation angles of principal axes were less than 1.0 degree for any influence radius and weighting factor