Ionic Dissolution Products of NovaBone® Promote Osteoblastic Proliferation via Influences on the Cell Cycle

This study investigated the effects of the ionic dissolution products of NovaBone® on osteoblastic proliferation and cell cycle regulation. MG63 osteoblast-like cells were cultured in NovaBone®-conditioned Dulbecco's Modified Eagle's Medium (DMEM) or control DMEM for 10 days. The concentration of silicon ions was significantly higher in NovaBone®-conditioned DMEM than control DMEM. MG63 cells cultured in NovaBone®-conditioned DMEM exhibited greater proliferation on days 1 and 4 than control cells. There were increased proportions of Novabone®-conditioned DMEM-cultured cells in the S and G2/M phases, and decreased proportions in the G0/G1 phase on days 1 and 4 versus control cells, while no differences were observed on days 7 and 10 between the two groups. Bone morphogenic protein 2 production increased in both groups, but was significantly higher for the NovaBone®-conditioned DMEM-cultured cells on day 10 compared with the controls. In conclusion, the NovaBone® ionic dissolution products, particularly the silicon ions, promoted proliferation of MG63 osteoblast-like cells in vitro via influences on the cell cycle.

Efficient differentiation of insulin-producing cells from skin-derived stem cells

OBJECTIVES

Type 1 diabetes mellitus, characterized by loss of pancreatic beta-cells, can be ameliorated by islet transplantation, but this treatment is restricted by the scarcity of islet tissue and by allograft rejection.

MATERIALS AND METHODS

We isolated and characterized skin-derived precursors (SKPs)--an abundant source of autologous cells--and developed an experimental strategy to convert them into insulin-producing cells (IPCs) in vitro within a short period of time, through extracellular factor modification and analyses of IPCs by reverse transcription-polymerase chain reaction, immunocytochemistry and enzyme-linked immunosorbent assay.

RESULTS

SKPs could self-assemble to form three-dimensional islet cell-like clusters (dithizone-positive) and co-express insulin and C-peptide. In addition, they expressed multiple genes related to pancreatic beta-cell development and function (e.g. insulin 1, insulin 2, islet-1, Pdx-1, NeuroD/beta2, glut-2 and Nkx6.1), but not other pancreas-specific hormones and enzymes (e.g. glucagon, somatostatin and amylase). Moreover, when stimulated with glucose, these cells synthesized and secreted insulin in a glucose-regulated manner.

CONCLUSIONS

The findings of this study indicate that SKPs can differentiate into functional IPCs and can provide an abundant source of autologous cells for transplantation. This study also provides strategies to derive autologous islet-replacement tissues from human skin stem cells.

Neutrophil elastase inhibitor prevents endotoxin-induced liver injury following experimental partial hepatectomy

Background

During endotoxaemia, neutrophils activated by inflammatory cytokines release reactive oxygen species and neutrophil elastase, resulting in hepatic necrosis and dysfunction. This study investigated the possible mechanism underlying the protective effect of sivelestat, a neutrophil elastase inhibitor, on endotoxin-induced liver injury following partial hepatectomy.

Methods

Lipopolysaccharide (LPS) was administered intravenously to male Sprague–Dawley rats 48 h after 70 per cent hepatectomy. Sivelestat or normal saline was given intravenously before LPS administration,

Results

Treatment with sivelestat significantly improved the survival rate. Sivelestat prevented increases in the concentration of serum enzymes and total bilirubin related to liver injury. Levels of inflammatory cytokines in serum and liver tissue were significantly lower in the sivelestat-treated group than in the control group. The degree of neutrophil infiltration, necrosis and apoptosis in the remnant liver was significantly decreased in sivelestat-treated rats. Sivelestat pretreatment inhibited the activation of nuclear factor (NF) κB, caspase 3 and 8 activities, and cytochrome c release.

Conclusion

Sivelestat prevents LPS-induced liver injury by inhibition of NF-κB activation and apoptosis.

Fibronectin protects endotoxin-induced liver injury after partial hepatectomy in rats

Endotoxemia following extended hepatectomy may be a cause of postoperative death. Multiple organ failure related to septemia is a common cause of early mortality after liver transplantation. Fibronectins (Fns) are involved in cellular adhesion, motility, differentiation, apoptosis, hemostasis, wound healing, and ischemic injury. Studies were performed to determine whether Fn influences the survival rate of rats subjected to endotoxin-induced liver injury after partial hepatectomy. Male Sprague-Dawley rats were intravenously administered lipopolysaccharide (LPS) 48 hours after 70% hepatectomy. Prior to LPS administration, plasma Fn or bovine serum albumin was given intravenously. The survival rate of the Fn-treated group was higher than that of the controls. Fn prevented increases in serum enzyme activity and total bilirubin related to liver injury. The levels of inflammatory cytokines including tumor necrosis factor-alpha, interleukin-1beta, and interleukin-6 interferon-gamma were also significantly lower in the Fn-treated than the control group. Furthermore, the number of apoptotic cells and the degree of necrosis in the remnant liver were significantly decreased in the Fn-treated rats compared with controls. These results indicate that Fn prevents endotoxin-induced liver injury after partial hepatectomy, at least in part through inhibiting the production of inflammatory cytokines, and the necrosis apoptosis in the remaining liver.

Isolation and characterization of endophytic Streptomyces strains from surface-sterilized tomato (Lycopersicon esculentum) roots

AIMS

To isolate endophytic Streptomyces strains from tomato and examine their antimicrobial activity.

METHODS

Endophytic Streptomyces strains were isolated using surface-sterilization methods and identified by morphological characteristics. Antimicrobial activities were measured by the agar plate sensitivity method. Antifungal activity in vivo was measured by seedling mortality in infested soils.

RESULTS

Twenty-one per cent of endophytic streptomycete isolates produced antibacterial metabolites and 41% produced antifungal metabolites in S medium. Sixty-five per cent of the most frequently isolated strains inhibited the growth of Rhizoctonia solani by the antibiosis assay but only 32% produced metabolites active against R. solani in S medium. Growth promotion and enhanced disease resistance of seedlings inoculated with Streptomyces sp. strain S30 were observed in tomato but not in cucumber seedlings.

CONCLUSIONS

Endophytic Streptomyces spp. strains were successfully isolated using stringent methods and strain S30 promoted growth and enhanced resistance to R. solani in tomato seedlings.

SIGNIFICANCE AND IMPACT OF THE STUDY

Endophytic streptomycetes showing antifungal activity in vitro and in vivo may indicate the potential for their use as biocontrol agents particularly of R. solani disease of tomato seedlings.

Enhanced airway inflammation and decreased subepithelial fibrosis in interleukin 6-deficient mice following chronic exposure to aerosolized antigen

BACKGROUND

Airway inflammation and remodelling are characteristic features of chronic asthma.

OBJECTIVE

To elucidate the role of interleukin (IL)-6 in airway responses to chronic antigen exposure.

METHODS

We compared airway inflammation, subepithelial collagen deposition, cytokine mRNA expression, and airway responsiveness between IL-6-deficient and wild-type (WT) mice following sensitization and repeated exposure to ovalbumin (OVA) three times a week for 8 weeks.

RESULTS

The repeated exposure to OVA induced infiltration of eosinophils, neutrophils, and lymphocytes into the airway, and caused thickening of the basement membrane and subepithelial fibrosis. IL-6-deficient mice exhibited more pronounced infiltration of these cells, a thinner basement membrane, and decreased subepithelial fibrosis, compared with WT mice. The repeated OVA exposure increased expression of IL-4, IL-13, eotaxin, monocyte chemoattractant protein-1 (MCP-1), and transforming growth factor-beta1 mRNA in WT mice. Among these factors, expression of IL-13 and MCP-1 mRNA was further enhanced in IL-6-deficient mice, compared with WT mice. However, both WT and IL-6-deficient mice exhibited similar levels of airway responsiveness to increasing doses of methacholine, even after repeated exposure to OVA.

CONCLUSION

These results suggest that IL-6 has dual roles in the chronic phase of asthma: down-regulation of inflammatory cell infiltration and enhancement of airway remodelling.

Fibronectin suppresses apoptosis and protects mice from endotoxic shock

Multiple-organ failure related to septicemia is a common cause of early mortality after liver transplantation. Endotoxemia following living donor hepatectomy may be a cause of postoperative death. Plasma fibronectin (Fn) exerts a broad range of biological effects on cellular adhesion, motility, differentiation, apoptosis, hemostasis, wound healing, reticuloendothelial system function, and ischemic injury. We studied the therapeutic effect of plasma Fn in mice after an intraperitoneal injection of lipopolysaccharide (LPS) and d-galactosamine (GalN). Female Balb/c mice received simultaneous intraperitoneal injection of LPS (50 microg/kg) and GalN (400 mg/kg). Thirty minutes prior to GalN/LPS administration, plasma Fn or bovine serum albumin was given intravenously. A single administration of plasma Fn (500 mg/kg) protected in dose-dependent fashion against lethal shock after GalN/LPS challenge. Plasma Fn significantly reduced the serum tumor necrosis factor-alpha, interferon-gamma, and interleukin-6 levels and significantly increased the serum interleukin-10 levels after GalN/LPS administration. Furthermore, plasma Fn significantly inhibited liver necrosis at 9 hours after GalN/LPS injection. The fraction of apoptotic-positive cells in these plasma Fn-treated mice was significantly lower than in the control group. These results support the protective treatment of endotoxin-induced liver injury by plasma Fn.

Recombinant anti-P protein autoantibodies isolated from a human autoimmune library: reactivity, specificity and epitope recognition

The ribosomal P proteins are specific and important autoantigens in patients affected by systemic lupus erythematosus. In this study, we describe for the first time the selection and characterization of recombinant human monoclonal anti-P protein (auto)-antibody fragments from an autoimmune patient-derived phage display antibody library. The selected recombinant anti-P antibodies specifically recognize the P proteins in immunofluorescence assays on HEp-2 cells and in immunoblotting assays, and they immunoprecipitate the P proteins under native conditions. Using both anti-P-positive patient sera and the selected recombinant anti-P antibodies, the immunodominant epitope was determined and shown to be located at the C-terminal end of the P proteins (amino acids 111-115). Inhibition of in vitro protein translation demonstrated that interaction of the monoclonal patient-derived anti-P antibodies with their native epitope functionally inhibits the activity of the P proteins on the ribosome, confirming the notion that patient autoantibodies are often directed to the functional centre of their autoantigenic target.

ApoE isoforms affect neuronal N-methyl-d-aspartate calcium responses and toxicity via receptor-mediated processes

Apolipoprotein E (apoE) alters the pathophysiology of Alzheimer's disease, but its mechanism is not fully understood. We examined the effects of recombinant human apoE3 and apoE4 on the neuronal calcium response to N-methyl-D-aspartate (NMDA), and compared them to their toxicity. ApoE4 (100 nM) significantly increased the resting calcium (by 70%) and the calcium response to NMDA (by 185%), whereas similar changes were not obtained in apoE3-treated neurons. ApoE4, but not apoE3, also significantly increased neurotoxicity, as evidenced by enhanced lactate dehydrogenase release (by 53%) and reduced 3-(4,5-dimethylthiazol-2-yl)-2,5,diphenyltetrazolium bromide levels (by 32%). ApoE4-induced changes in the calcium response to NMDA and associated neurotoxicity were blocked by coincubation with MK-801. Both the receptor-associated protein, which inhibits interaction of apoE with members of the LDL receptor family, including the low-density lipoprotein receptor-related protein (LRP), and activated alpha2-macroglobulin, another LRP ligand, prevented apoE4-induced enhancement of the calcium response to NMDA, resting calcium levels, and neurotoxicity. A tandem apoE peptide (100 nM) containing only the receptor binding region residues also eliminated the enhanced calcium signaling and neurotoxicity by apoE4. Taken together, our data demonstrate that differential effects of apoE3 and apoE4 on the calcium signaling in neurons correlate with their effect on neurotoxicity, which are secondary to receptor binding.

A disulfide bond is required for functional assembly of NCX1 from complementary fragments

The cardiac Na(+)-Ca(2+) exchanger consists of a single polypeptide with two transmembrane segment (TMS) clusters separated by a large intracellular loop between TMS5 and TMS6 (Nicoll et al. (1999) J. Biol. Chem. 274, 910-917; Iwamoto et al. (1999) FEBS Lett. 446, 264-268). A "split" exchanger can be expressed by dividing the exchanger cDNA into two fragments so that the NH(2)- and CO(2)H-terminal portions of the protein are expressed as separate polypeptides in HEK293 cells. Expression of partial exchanger molecules did not result in detectable exchanger activity. Cells coexpressing both portions of the exchanger, however, displayed between 30 and 50% of the activity of the intact wild-type exchanger. The full-length exchanger contains a disulfide bond between residues 14 or 20 and 792. We examined the role of this disulfide bond in the split exchanger by mutagenesis and expression studies. Our results indicate that the function of the exchanger requires both TMS clusters and that the C(14 or 20)/C792 disulfide bond is essential for expression of active exchangers from half molecules.

Structure-activity relationship studies of a bisbenzimidazole-based, Zn(2+)-dependent inhibitor of HCV NS3 serine protease

A survey of isosteric replacements of the phosphonoalanine side chain coupled with a process of conformational constraint of a bisbenzimidazole-based, Zn(2+)-dependent inhibitor of hepatitis C virus (HCV) NS3 serine protease resulted in the identification of novel series of active compounds with extended side chains. However, Zn(2+)-dependent HCV NS3 inhibition was relatively insensitive to the structural variations examined but dependent on the presence of negatively charged functionality. This result was interpreted in the context of an initial electrostatic interaction between protease and inhibitor that is subsequently consolidated by Zn(2+), with binding facilitated by the featureless active site and proximal regions of the HCV NS3 protein.

[Adenovirus-mediated transfer of human wild-type p53, GM-CSF, and B7-1 genes efficiently produces growth suppression and apoptosis of hepatocellular cells in vitro]

OBJECTIVE

To investigate the tumor suppressor activity of recombinant adenovirus vector expressing the human wild-type p53, GM-CSF, and B7-1 proteins (designated as BB-102) in human hepatocellular carcinoma cells (HCC) in vitro.

METHODS

The wild-type p53 BEL-7402, mutant p53 HLE, and HuH-7 HCC cell lines were infected with BB-102 at MOI of 50 in vitro. Immunohistochemical assay was used to determine p53 expressed by BB-102. Tumor suppressor activity of the expressed p53 was identified by terminal deoxynucleotidy I transferase (TdT) assay in BB-102-infected HCC cell lines.

RESULTS

p53 protein was found to express in a dose-dependent manner in BB-102-infected HCC cell lines. The proliferation of HCC cell lines were suppressed significantly at the average rates of 58.5%, 81.5%, and 71.1% for BEL-7402, HLE, and HuH-7 respectively from 4 to 10 days, accompanying inducing apoptosis in BB-102-infected HCC cell lines.

CONCLUSIONS

Besides the expression of B7-1 and GM-CSF, BB-102 is able to express p53 protein in independent manner and exerts its anti-tumor activity, which suggests that BB-102 may be useful for gene therapy against HCC in vivo.

A novel approach for studying endogenous abeta processing using cultured primary neurons isolated from APP transgenic mice

The central component of senile amyloid plaques in Alzheimer's disease (AD) is the beta-amyloid peptide (Abeta), derived from proteolytic processing of the amyloid precursor protein (APP). In this study, we developed an in vitro model to measure and identify soluble Abeta from primary cortical neurons. Neurons were isolated from mice transgenic for human APP695 containing the K670N, M671L double mutation. We characterized soluble Abeta using Western blot and ELISA assays. We found that the Abeta levels in conditioned media from these neurons were readily detectable and almost five times higher than in CSF. The majority of Abeta in the media was Abeta1-40; however, Abeta1-42 was also detectable. When the neurons were exposed to Phorbol 12-myristate 13-acetate (PMA), alpha1-antichymotrypsin, or alpha1-antitrypsin, the alterations of soluble Abeta levels were consistent with other models reported. Most importantly, the soluble Abeta in our model was remarkably stable, and aliquots were unchanged after prolonged incubations or repeated freeze/thaw cycles. The Abeta appeared to be monomeric by Western blot analysis. Soluble Abeta coimmunoprecipitated with endogenous mouse apolipoprotein E from the primary cultures. Taken together, our data demonstrated that using a Western blot assay to detect soluble Abeta from transgenic mouse overexpressing APP695 is sensitive, specific, and reliable and provides an accessible model for examining the neuronal metabolism of APP and Abeta.

Co-transfer of human wild-type p53 and granulocyte-macrophage colony-stimulating factor genes via recombinant adenovirus induces apoptosis and enhances immunogenicity in laryngeal cancer cells

Co-transfer of immunomodulatory and anti-proliferative genes may be the basis for new strategies to enhance tumor regression. The purpose of this study was to develop a combination gene therapy strategy for the treatment of laryngeal cancer. Human wild-type p53 and granulocyte-macrophage colony-stimulating factor (GM-CSF) genes were transferred into human laryngeal cancer cells mediated by adenovirus type 5 vector co-expressing human wild-type p53 and GM-CSF (Ad-p53/GM-CSF). By the introduction of the wild-type p53 gene, the growth of human laryngeal cancer Hep-2 cells was inhibited and their apoptosis was induced. By the introduction of the GM-CSF gene, the immunogenicity of cancer cells was enhanced. Significant proliferation of tumor infiltrating lymphocytes and tumor-specific cytotoxicity of cytotoxic T lymphocytes were induced by Ad-p53/GM-CSF-infected cancer cells in vitro. The results suggest that the co-transfer of human wild-type p53 and GM-CSF genes into tumor cells via recombinant adenovirus may be further developed into an effective and practical combination gene therapy strategy for laryngeal cancer.

Split Na+-Ca2+ exchangers. Implications for function and expression

The Na(+)-Ca(2+) exchanger has nine transmembrane segments, with a large cytoplasmic loop between the fifth and sixth transmembrane segments. The protein was split within the cytoplasmic loop into two domains consisting of the first five transmembrane segments and the last four transmembrane segments, respectively. The two domains were either expressed individually or coexpressed. Each of the two domains with different lengths of the cytoplasmic loop was fused to green fluorescent protein. We show that coexpression of both domains is required for proper membrane targeting and for expression of functional exchange activity. Fusion to green fluorescent protein does not alter biophysical properties of the exchange process. In addition, truncation of a large portion of the cytoplasmic loop does not alter important properties of the exchanger such as Na(+)-dependent inactivation, activation by chymotrypsin, or exchanger inhibitory peptide (XIP) sensitivity.

Elevation of LDL receptor-related protein levels via ligand interactions in Alzheimer disease and in vitro

The low-density lipoprotein (LDL) receptor-related protein (LRP) is a multifunctional receptor in the CNS that binds both apolipoprotein E (apoE) and activated alpha2-macroglobulin (alpha2M*); all 3 proteins are genetically associated with Alzheimer disease (AD). In this study we found an 85% increase in LRP levels in human AD brain frontal cortex, along with an increased level of the LRP ligands, apoE, and alpha2M. We speculated that LRP levels might be increased in response to the increased levels of its ligands, apoE, and alpha2M*. To test this hypothesis we examined the effects of alpha2M* on LRP in primary cultures. Treatment of neurons with alpha2M* significantly increased LRP levels (by 92%). This increase was prevented by coculture with receptor-associated protein (RAP), which blocks binding of LRP ligands to LRP Native alpha2M or RAP alone did not change LRP levels in vitro. We also found that alpha2M* stimulated activation of astrocytes in vitro and promoted the levels of LRP by 65%. These data indicate 1) the LRP ligand alpha2M* increases levels of LRP in primary neuronal and astrocytic cultures, 2) alpha2M*-induction of LRP levels in vitro depends on binding to LRP, and 3) LRP levels are increased in AD brain, perhaps in response to the increased levels of alpha2M.

DNA synthesis and mitotic clonal expansion is not a required step for 3T3-L1 preadipocyte differentiation into adipocytes

Upon differentiation induction of 3T3-L1 preadipocytes by a hormone mixture containing 1-isobutyl-3-methylxanthine, dexamethasone, and insulin, the preadipocytes undergo approximately 2 rounds of mitotic clonal expansion, which just precedes the adipogenic gene expression program and has been thought to be an essential early step for differentiation initiation. By inducing 3T3-L1 preadipocytes with each individual hormone, it was determined that the mitotic clonal expansion was induced only by insulin and not by 1-isobutyl-3-methylxanthine or dexamethasone. Cell number counting and fluorescence-activated cell-sorting analysis indicated that a significant fraction of 3T3-L1 preadipocytes differentiated into adipocytes without mitotic clonal expansion when induced with the combination of 1-isobutyl-3-methylxanthine and dexamethasone. Furthermore, when normally induced 3T3-L1 preadipocytes were treated with PD98059 (an inhibitor of mitogen-activated protein kinase/extracellular signal-regulated kinase kinase 1) to block the activation of extracellular signal-regulated kinase (Erk) 1 and Erk2, the mitotic clonal expansion was blocked, but adipocyte differentiation was not affected. These observations were confirmed by bromodeoxyuridine labeling. The differentiated adipocytes induced with 1-isobutyl-3-methylxanthine and dexamethasone or standard hormone mixture plus PD98059 were not labeled by bromodeoxyuridine. Thus, it is evident that 3T3-L1 preadipocytes could differentiate into adipocytes without DNA synthesis and mitotic clonal expansion. Our results also suggested that activation of Erk1 and Erk2 is essential to but not sufficient for induction of mitotic clonal expansion.

Gene expression profile changes in initiation and progression of squamous cell carcinoma of esophagus

Tumorigenesis is a complex process involving multiple genes. As a step toward understanding the complicated changes between normal and malignant cells, this report focused on gene expression profile variations among normal and abnormal esophageal epithelium tissues. The cDNA microarray approach was used to investigate gene expression profiles of 5 different stages during initiation and progression of esophageal cancer. According to pathological characteristics, these 5 stages were normal, dysplasia I (mild dysplasia), dysplasia II (moderate dysplasia), carcinoma in situ (CIS) and squamous cell carcinoma of esophagus (SCC). Comparing and analyzing those gene expression profiles, we observed that the expression levels of many genes changed in dysplasia I and some known tumor-related genes were over-expressed or under-expressed in all 4 abnormal stages. Using principle component analysis we identified a set of genes that may play an important role in tumor development. Hybridization data were confirmed by semi-quantitative reverse transcription-polymerase chain reaction and immunohistochemistry. These results suggest that cDNA microarray technology is a useful tool to discover genes frequently involved in esophageal neoplasia and provides novel clues to diagnosis, early detection and intervention of SCC.