Stem cells from deciduous tooth repair mandibular defect in swine

Stem cells from human exfoliated deciduous teeth have been identified as a new post-natal stem cell population with multipotential differentiation capabilities, including regeneration of mineralized tissues in vivo. To examine the efficacy of utilizing these stem cells in regenerating orofacial bone defects, we isolated stem cells from miniature pig deciduous teeth and engrafted the critical-size bone defects generated in swine mandible models. Our results indicated that stem cells from miniature pig deciduous teeth, an autologous and easily accessible stem cell source, were able to engraft and regenerate bone to repair critical-size mandibular defects at 6 months post-surgical reconstruction. This pre-clinical study in a large-animal model, specifically swine, allows for testing of a stem cells/scaffold construct in the restoration of orofacial skeletal defects and provides rapid translation of stem-cell-based therapy in orofacial reconstruction in human clinical trials.

Inhibition of human dental pulp stem cell differentiation by Notch signaling

Notch signaling plays a critical role in development and cell fate specification. Notch receptors and ligands have been found to be expressed in dental epithelium or mesenchyme in the developing tooth, suggesting that Notch signaling may regulate odontogenesis. Post-natal human dental pulp stem cells (DPSCs) isolated from the dental pulp have characteristics of mesenchymal stem cells and can differentiate into odontoblasts. In this study, we examined whether Notch signaling regulated the odontoblastic differentiation of DPSCs. We found that over-expression of the Notch ligand, Jagged-1, activated the Notch signaling pathway in DPSCs. Jagged-1 inhibited the odontoblastic differentiation of DPSCs in vitro. Jagged-1-expressing DPSCs could not form mineralized tissues in vivo. Moreover, over-expression of the constitutively activated Notch1 intracellular domain (Notch-ICD) also inhibited odontoblastic differentiation of DPSCs. Taken together, our results demonstrate that Notch signaling can inhibit the odontoblastic differentiation of DPSCs.

The miniature pig: a useful large animal model for dental and orofacial research

Compared with small animal models such as rodents, large animal models are superior in many aspects for the study of human diseases and pre-clinical therapies. Since the development of the Minnesota miniature pig in 1949 at the Hormel Institute (USA), miniature pigs have been used as a large animal model in medical studies for scientific, economic, and ethical reasons. The oral maxillofacial region of miniature pigs is similar to that of humans in anatomy, development, physiology, pathophysiology, and disease occurrence. In this review, we describe the anatomical characteristics of the oral maxillofacial system of the miniature pig, established models of oral diseases in this animal, and other uses of the miniature pig in orofacial research.

Spatiotemporal patterns of postsynaptic density (PSD)-95 expression after rat spinal cord injury

AIMS

Postsynaptic density (PSD)-95 is a scaffolding protein linking the N-methyl-D-aspartate receptor with neuronal nitric oxide synthase (nNOS), which contributes to many physiological and pathological actions. We here investigated whether PSD-95 was involved in the secondary response following spinal cord injury (SCI).

METHODS

Spinal cord contusion (SCC) and spinal cord transection (SCT) models at thoracic (T) segment 9 (T(9)) were established in adults rats. Real-time polymerase chain reaction, Western blot, immunohistochemistry and immunofluorescence were used to detect the temporal profile and spatial distribution of PSD-95 after SCI. The association between PSD-95 and nNOS in the injured cords was also assessed by coimmmunoprecipation and double immunofluorescent staining.

RESULTS

The mRNA and protein for PSD-95 expression were significantly increased at 2 h or 8 h, and then gradually declined to the baseline level, ultimately up-regulated again from 5 days to 7 days for its mRNA level and at 7 days or 14 days for its protein level after either SCC or SCT. PSD-95 immunoreactivity was found in neurones, oligodendrocytes and synaptic puncta of spinal cord tissues within 5 mm from the lesion site. Importantly, injury-induced expression of PSD-95 was colabelled by active caspase-3 (apoptotic marker), Tau-1 (the marker for pathological oligodendrocytes) and nNOS.

CONCLUSIONS

Accompanied by the spatio-temporal changes for PSD-95 expression, the association between PSD-95 and nNOS undergoes substantial alteration after SCI. These two molecules are likely to form a complex on apoptotic neurones and pathological oligodendrocytes, which may in turn be involved in the secondary response after SCI.

Human Hertwig's epithelial root sheath cells play crucial roles in cementum formation

Hertwig's epithelial root sheath (HERS) cells are a unique population of epithelial cells in the periodontal ligament compartment. To date, their functional role has not been fully elucidated. Our hypothesis was that HERS cells may be involved in regulating differentiation of periodontal ligament stem cells (PDLSCs) and forming cementum in vivo. In this study, we found that HERS cells may be capable of promoting PDLSC differentiation and undergoing epithelial-mesenchymal transition in vitro. Immunohistochemical staining, Western blot analysis, a transwell co-culture system, and in vivo transplantation were used to characterize the interplay between HERS cells and PDLSCs, as well as the epithelial-mesenchymal transition (EMT) of HERS cells. TGFbeta1 was capable of inducing the epithelial-mesenchymal transition of HERS cells through activating the PI3K/AKT pathway. Furthermore, HERS cells were able to form cementum-like tissue when transplanted into immunocompromised mice.

ABBREVIATIONS

bone marrow mesenchymal stem cell, BMMSC; bone sialoprotein, BSP; hydroxyapatite/tricalcium phosphate, HA/TCP; Hertwig's epithelial root sheath, HERS; osteocalcin, OCN; periodontal ligament, PDL; periodontal ligament stem cell, PDLSC; phosphatidylinositol 3-kinase, PI3K.

Gene therapy for articular cartilage repair

Articular cartilage serves as the gliding surface of joints. It is susceptible to damage from trauma and from degenerative diseases. Restoration of damaged articular cartilage may be achievable through the use of cell-regulatory molecules that augment the reparative activities of the cells, inhibit the cells' degradative activities, or both. A variety of such molecules have been identified. These include insulin-like growth factor I, fibroblast growth factor 2, bone morphogenetic proteins 2, 4, and 7, and interleukin-1 receptor antagonist. It is now possible to transfer the genes encoding such molecules into articular cartilage and synovial lining cells. Although preliminary, data from in-vitro and in-vivo studies suggest that gene therapy can deliver such potentially therapeutic agents to protect existing cartilage and to build new cartilage.

Craniofacial tissue engineering by stem cells

Craniofacial tissue engineering promises the regeneration or de novo formation of dental, oral, and craniofacial structures lost to congenital anomalies, trauma, and diseases. Virtually all craniofacial structures are derivatives of mesenchymal cells. Mesenchymal stem cells are the offspring of mesenchymal cells following asymmetrical division, and reside in various craniofacial structures in the adult. Cells with characteristics of adult stem cells have been isolated from the dental pulp, the deciduous tooth, and the periodontium. Several craniofacial structures--such as the mandibular condyle, calvarial bone, cranial suture, and subcutaneous adipose tissue--have been engineered from mesenchymal stem cells, growth factor, and/or gene therapy approaches. As a departure from the reliance of current clinical practice on durable materials such as amalgam, composites, and metallic alloys, biological therapies utilize mesenchymal stem cells, delivered or internally recruited, to generate craniofacial structures in temporary scaffolding biomaterials. Craniofacial tissue engineering is likely to be realized in the foreseeable future, and represents an opportunity that dentistry cannot afford to miss.

Bone marrow-derived mesenchymal stem cells for regenerative medicine in craniofacial region

The craniofacial region contains many specified tissues including bone, cartilage, muscle, blood vessels and neurons. Defect or dysfunction of the craniofacial tissue after post-cancer ablative surgery, trauma, congenital malformations and progressive deforming skeletal diseases has a huge influence on the patient's life. Therefore, functional reconstruction of damaged tissues is highly expected. Bone marrow-derived mesenchymal stem cells (BMMSCs) are one of the most well characterized postnatal stem cell populations, and considered to be utilized for cell-based clinical therapies. Here, the current understanding and the potential applications in craniofacial tissue regeneration of BMMSCs are reviewed, and the current limitations and drawbacks are also discussed.

Ovine periodontal ligament stem cells: isolation, characterization, and differentiation potential

Periodontal disease leads to destruction of the connective tissues responsible for restraining teeth within the jaw. To date, various conventional therapies for periodontal regeneration have shown limited and variable clinical outcomes. Recent studies have suggested that newly identified human periodontal ligament stem cells (PDLSCs) may offer an alternate and more reliable strategy for the treatment of periodontal disease using a cell-based tissue engineering approach. In the present study, we generated enriched preparations of PDLSCs derived from ovine periodontal ligament using immunomagnetic bead selection, based on expression of the mesenchymal stem cell-associated antigen CD106 (vascular cell adhesion molecule 1). These CD106+ ovine PDLSCs demonstrated the capacity to form adherent clonogenic clusters of fibroblast-like cells when plated at low densities in vitro. Ex vivo-expanded ovine PDLSCs exhibited a high proliferation rate in vitro and expressed a phenotype (CD44+, CD166+, CBFA-1+, collagen-I+, bone sialoprotein+) consistent with human-derived PDLSCs. Furthermore, cultured ovine PDLSCs expressed high transcript levels of the ligament/tendon-specific early transcription factor scleraxis. Importantly, ex vivo-expanded ovine PDLSCs demonstrated the capacity to regenerate both cementum-like mineral and periodontal ligament when transplanted into NOD/SCID mice. The results from the present study suggest that ovine PDLSCs may potentially be used as a novel cellular therapy to facilitate successful and more predictable regeneration of periodontal tissue using an ovine preclinical model of periodontal disease as a prelude to human clinical studies.

Stem cells in the periodontal ligament

The ability to identify and manipulate stem cells has been a significant advancement in regenerative medicine and has contributed to the development of tissue engineering-based clinical therapies. Difficulties associated with achieving predictable periodontal regeneration, means that novel techniques such as tissue engineering need to be developed in order to regenerate the extensive soft and hard tissue destruction that results from periodontitis. One of the critical requirements for a tissue engineering approach is the delivery of ex vivo expanded progenitor populations or the mobilization of endogenous progenitor cells capable of proliferating and differentiating into the required tissues. By definition, stem cells fulfill these requirements and the recent identification of stem cells within the periodontal ligament represents a significant development in the progress toward predictable periodontal regeneration. In order to explore the importance of stem cells in periodontal wound healing and regeneration, this review will examine contemporary concepts in stem cell biology, the role of periodontal ligament progenitor cells in the regenerative process, recent developments in identifying periodontal stem cells and the clinical implications of these findings.

Essential role of Ca2+ release channels in angiotensin II-induced Ca2+ oscillations and mesangial cell contraction

The increased resistance of the glomerulus as a result of contractile dysfunction of mesangial cells (MCs) is associated with reduction of glomerular filtration rate and development of glomerulosclerosis. Evidences show MCs contraction changes with intracellular Ca(2+) concentration ([Ca(2+)](i)). Here, we explore the mechanism of angiotensin II (AngII)-induced Ca(2+) oscillations and MCs contraction. Primary MCs from 3-month-old and 28-month-old rats were used for detection of Ca(2+) oscillations and MC planar area with confocal microscopy. AngII could induce typical Ca(2+) oscillations and contraction of MCs. This process was abolished by thapsigargin, 2-aminoethoxydiphenyl borate, or 1-O-octadecyl-2-O-methyl-sn-glycero-3-phosphorylcholine, and partially inhibited by ryanodine, but could not be inhibited in the absence of extracellular Ca(2+). Ryanodine receptors (RyRs) and inositol 1,4,5-trisphosphate (InsP(3)) receptors displayed a strong colocalization, which may contribute to the amplification of Ca(2+) response. MLC(20) phosphorylation and MC planar area were associated with AngII-induced Ca(2+) oscillations. The frequency of Ca(2+) oscillations was dependent on the AngII concentration and correlated with the MCs' contractive extent, which could be attenuated by KN-93. The amplitude reduction of oscillations correlated with the decrease in aging-related contraction. In conclusion, [Ca(2+)](i) response of MCs to AngII is characterized by repetitive spikes through the following repetitive cycles: Ca(2+) release by phospholipase C -InsP(3) pathway, Ca(2+) amplification by Ca(2+)-activated RyRs and Ca(2+) reuptake by the endoplasmic reticulum. MCs contraction can be modulated by oscillations not only in an AngII-induced frequency-dependent mode but also in an aging-related, amplitude-dependent mode.

Enhanced Magnetic Properties of Self-Assembled FePt Nanoparticles with MnO Shell

Self-assembled FePt/MnO nanoparticles with different morphology and size were synthesized with a polyol process. With the MnO coating, FePt nanoparticles exhibit a high blocking temperature and magnetic moment. The low-temperature hysteresis loop of FePt nanoparticles can be shifted through the AFM pinning of the MnO shell. The aggregation of FePt nanoparticles during the L10 phase transformation can be significantly decreased by coating with the MnO shell.

NF-kappaB activation in human dental pulp stem cells by TNF and LPS

Post-natal human dental pulp stem cells (DPSCs) represent a unique precursor population in the dental pulp, which has multipotential and can regenerate a dentin/pulp-like structure. Because the dental pulp is frequently infected by oral bacteria due to dental decay, in this study, we examined whether lipopolysaccharide (LPS) and tumor necrosis factor (TNF) activated the immunologic transcription factor nuclear factor kappa B (NF-kappaB) in DPSCs. We found that both TNF and LPS activated the I-kappa B kinase complex (IKK) in DPSCs to induce the phosphorylation and degradation of IkappaBalpha, resulting in the nuclear translocation of NF-kappaB. Consistently, both TNF and LPS rapidly induced the expression of the NF-kappaB-dependent gene interleukin-8 (IL-8). However, unlike in monocytes, we found that LPS could not induce the phosphorylation of the NF-kappaB active subunit p65 in DPSCs. In summary, our studies suggest that DPSCs may be involved in immune responses during pulpal infection through activating NF-kappaB.

Recovery of stem cells from cryopreserved periodontal ligament

Human post-natal stem cells possess a great potential to be utilized in stem-cell-mediated clinical therapies and tissue engineering. It is not known whether cryopreserved human tissues contain functional post-natal stem cells. In this study, we utilized human periodontal ligament to test the hypothesis that cryopreserved human periodontal ligament contains retrievable post-natal stem cells. These cryopreserved periodontal ligament stem cells maintained normal periodontal ligament stem cell characteristics, including expression of the mesenchymal stem cell surface molecule STRO-1, single-colony-strain generation, multipotential differentiation, cementum/periodontal-ligament-like tissue regeneration, and a normal diploid karyotype. Collectively, this study provides valuable evidence demonstrating a practical approach to the preservation of solid-frozen human tissues for subsequent post-natal stem cell isolation and tissue regeneration. The present study demonstrates that human post-natal stem cells can be recovered from cryopreserved human periodontal ligament, thereby providing a practical clinical approach for the utilization of frozen tissues for stem cell isolation.

Characterization of prolyl iminopeptidase-deficient Neisseria gonorrhoeae

Prolyl iminopeptidase (PIP) is an enzyme produced by Neisseria gonorrhoeae, the detection of which is incorporated into several commercial test panels. In this report we describe two distinct mutations in the pip gene which account for the loss of PIP activity.

The efficacy of mesenchymal stem cells to regenerate and repair dental structures

OBJECTIVES

Identification, characterization, and potential application of mesenchymal stem cells (MSC) derived from human dental tissues.

METHODS

Dental pulp and periodontal ligament were obtained from normal human impacted third molars. The tissues were digested in collagenase/dispase to generate single cell suspensions. Cells were cultured in alpha-MEM supplemented with 20% fetal bovine serum, 2 mM l-glutamine, 100 microM l-ascorbate-2-phosphate. Magnetic and fluorescence activated cell sorting were employed to characterize the phenotype of freshly isolated and ex vivo expanded cell populations. The developmental potential of cultured cells was assessed following co-transplantation with hydroxyapetite/tricalcium phosphate (HA/TCP) particles into immunocompromised mice for 8 weeks.

RESULTS

MSC were identified in adult human dental pulp (dental pulp stem cells, DPSC), human primary teeth (stem cells from human exfoliated deciduous teeth, SHED), and periodontal ligament (periodontal ligament stem cells, PDLSC) by their capacity to generate clongenic cell clusters in culture. Ex vivo expanded DPSC, SHED, and PDLSC populations expressed a heterogeneous assortment of makers associated with MSC, dentin, bone, smooth muscle, neural tissue, and endothelium. PDLSC were also found to express the tendon specific marker, Scleraxis. Xenogeneic transplants containing HA/TCP with either DPSC or SHED generated donor-derived dentin-pulp-like tissues with distinct odontoblast layers lining the mineralized dentin-matrix. In parallel studies, PDLSC generated cementum-like structures associated with PDL-like connective tissue when transplanted with HA/TCP into immunocompromised mice.

CONCLUSION

Collectively, these data revealed the presence of distinct MSC populations associated with dental structures with the potential of stem cells to regenerate living human dental tissues in vivo.

Comparison of stem-cell-mediated osteogenesis and dentinogenesis

The difference between stem-cell-mediated bone and dentin regeneration is not yet well-understood. Here we use an in vivo stem cell transplantation system to investigate differential regulation mechanisms of bone marrow stromal stem cells (BMSSCs) and dental pulp stem cells (DPSCs). Elevated expression of basic fibroblast growth factor (bFGF) and matrix metalloproteinase 9 (MMP-9, gelatinase B) was found to be associated with the formation of hematopoietic marrow in BMSSC transplants, but not in the connective tissue of DPSC transplants. The expression of dentin sialoprotein (DSP) specifically marked dentin synthesis in DPSC transplants. Moreover, DPSCs were found to be able to generate reparative dentin-like tissue on the surface of human dentin in vivo. This study provided direct evidence to suggest that osteogenesis and dentinogenesis mediated by BMSSCs and DPSCs, respectively, may be regulated by distinct mechanisms, leading to the different organization of the mineralized and non-mineralized tissues.

Tsunami hazards in Europe

Tsunami represents one of the most potentially serious forms of coastal flood risk. Although much is known on the recorded history of tsunamis for given areas of the world, very little information is available on the occurrence of palaeotsunamis during prehistory. This is of fundamental importance in calculating tsunami flood risk for any given coastal area. Given sufficient information on past tsunami activity for a particular coastal area, the numerical calculation of aggregate coastal flood risk (including tsunami) for a coastal area is very difficult to estimate since one needs also to take into account the risk of a tsunami and a storm surge taking place simultaneously during a high tide. Estimates of coastal flood risk also need to consider future changes in relative sea level caused by the combined effects of global climate change and vertical movements of the lithosphere.

Stem cell properties of human dental pulp stem cells

In this study, we characterized the self-renewal capability, multi-lineage differentiation capacity, and clonogenic efficiency of human dental pulp stem cells (DPSCs). DPSCs were capable of forming ectopic dentin and associated pulp tissue in vivo. Stromal-like cells were reestablished in culture from primary DPSC transplants and re-transplanted into immunocompromised mice to generate a dentin-pulp-like tissue, demonstrating their self-renewal capability. DPSCs were also found to be capable of differentiating into adipocytes and neural-like cells. The odontogenic potential of 12 individual single-colony-derived DPSC strains was determined. Two-thirds of the single-colony-derived DPSC strains generated abundant ectopic dentin in vivo, while only a limited amount of dentin was detected in the remaining one-third. These results indicate that single-colony-derived DPSC strains differ from each other with respect to their rate of odontogenesis. Taken together, these results demonstrate that DPSCs possess stem-cell-like qualities, including self-renewal capability and multi-lineage differentiation.

[Studies on voice identification]

The spectrographic method of voice identification was investigated and its application in forensic sciences was discussed.

Role of Src kinase in diperoxovanadate-mediated activation of phospholipase D in endothelial cells

We have shown earlier that oxidant-induced activation of phospholipase D (PLD) in vascular endothelial cells (ECs) is regulated by protein tyrosine kinases. To further understand the regulation of oxidant-induced PLD activation, we investigated the role of Src kinase. Treatment of bovine pulmonary artery ECs (BPAECs) with a model oxidant, diperoxovanadate (DPV), at 5 microM concentration, for 30 min, stimulated PLD activity (four- to eightfold), which was attenuated by tyrosine kinase inhibitors and by Src kinase-specific inhibitors PP-1 and PP-2, in a dose- and time-dependent fashion. Furthermore, BPAECs exposed to DPV (5 microM) for 2 min showed activation of Src kinase as observed by increased tyrosine phosphorylation and autophosphorylation in Src immunoprecipitates, which was attenuated by PP-2. Src immunoprecipitates of cell lysates from control BPAECs exhibited PLD activity in cell-free preparations, which was Arf- and Rho-sensitive and was enhanced at 2 min of DPV (5 microM) treatment. Also, Western blots of Src immunoprecipitates of control cells revealed the presence of PLD(1) and PLD(2), suggesting the association of PLD with Src kinase under basal conditions. However, exposure of cells to DPV (5 microM) for 2 min enhanced the association of PLD(2) but not PLD(1) with Src. Western blotting of immunoprecipitates of PLD(1) and PLD(2) isoforms of control BPAECs revealed the presence of Src under basal conditions and exposure of cells to DPV (5 microM) for 2 min enhanced the association of PLD(2) with Src in PLD(2) immunoprecipitates. Transient expression of a dominant negative mutant of Src in BPAECs attenuated DPV- but not TPA-induced PLD activation. In cell-free preparations, Src did not phosphorylate either PLD(1) or PLD(2) compared to protein kinase Calpha or p38 mitogen-activated protein kinase. These data show for the first time a direct association of Src with PLD in ECs and regulation of PLD in intact cells.

Comparison of human dental pulp and bone marrow stromal stem cells by cDNA microarray analysis

We compared the gene expression profiles of human dental pulp stem cells (DPSCs) and bone marrow stromal stem cells (BMSSCs) as representative populations of odontoprogenitor and osteoprogenitor cells, respectively. Total RNA from primary cultures was reverse-transcribed to generate cDNA probes and then hybridized with the Research Genetics human gene microarray filter GF211. The microarrays were analyzed using the PATHWAYS software package. Human DPSCs and BMSSCs were found to have a similar level of gene expression for more than 4000 known human genes. A few differentially expressed genes, including collagen type XVIII alpha1, insulin-like growth factor-2 (IGF-2), discordin domain tyrosine kinase 2, NAD(P)H menadione oxidoreductase, homolog 2 of Drosophila large disk, and cyclin-dependent kinase 6 were highly expressed in DPSCs, whereas insulin-like growth factor binding protein-7 (IGFBP-7), and collagen type I alpha2 were more highly expressed in BMSSCs. Furthermore, we confirmed the differential expression of these genes by semiquantitative polymerase chain reaction (PCR) and northern blot hybridization. The protein expression patterns for both IGF-2 and IGFBP-7 correlated with the differential mRNA levels seen between DPSCs and BMSSCs. This report describes the gene expression patterns of two distinct precursor populations associated with mineralized tissue, and provides a basis for further characterization of the functional roles for many of these genes in the development of dentin and bone.

Expression and deletion analysis of EcoRII endonuclease and methylase gene

OBJECTIVE

To clone complete EcoRII restriction endonuclease gene (ecoRIIR) and methyltransferase gene (ecoRIIM) in one vector and to analyze the coordinating expression of this whole R-M system.

METHODS

Unidirectional deletion subclones were constructed with ExoIII. ecoRIIR/ M genes were preliminarily located in the cloned fragment according to the enzyme activities of subclones. Exact deletion sites were determined by sequencing, and transcriptional start sites were determined by S1 mapping.

RESULTS

The DNA fragment which was cloned into pBluescript SK + contained intact ecoRIIR gene and ecoRIIM gene, and two transcriptional start sites of ecoRIIR gene were determined. 132bp to 458bp from 3'end of ecoRIIR gene are indispensable to enzyme activities and deletion of 202bp from 3' end of ecoRIIM gene made enzyme lose the capability in DNA protection to resist specific cut with EcoRII endonuclease (EcoRII. R). Deletion of the coding and flanking sequences of one gene did not affect the expression of the other gene, and the recombinants only containing ecoRIIR gene appeared to be lethal to dcm+ host.

CONCLUSION

ecoRIIM gene linking closely to ecoRIIR gene is very important for the existence of the R-M system in process of evolution, but the key to control EcoRII R-M order may not exist in transcriptional level .

Electromagnetic analysis of axially symmetric diffractive optical elements illuminated by oblique incident plane waves

We present an analysis of axially symmetric diffractive optical elements illuminated by off-axis or oblique incident plane waves. The analysis is performed with a finite-difference time-domain method that has been formulated to exploit axial symmetry yet accommodate off-axis illumination. This approach is compared with a full three-dimensional formulation and is found to be more efficient in both memory requirements and computational time. Validation and applications of this method are presented.

[A study on the change of caries activity of children with fixed orthodontic treatment]

OBJECTIVE

To investigate the change of caries activity in children with fixed appliance.

METHODS

30 children of permanent dentition were treated with edgewise appliance. CAT was used to test the degree of caries activity before the orthodontic treatment, at the first week, at the first month, at the third month and at the sixth month of appliance bonding respectively.

RESULTS

Compared with pre-treatment, there was a significant difference of CAT at the first, third and sixth month of treatment; compared with the first week of treatment, there was also a significant difference of CAT at the third and sixth month of treatment.

CONCLUSIONS

The CAT degree increases in children with fixed orthodontic appliance and these children are more sensitive to dental caries.

[Study on Gong Dingguo]

It is proved through textual researches that Gong Dingguo, the author of Neifu Michuan Jingyan Nuke, was the son of gong Tingxian, a famous physician of the late Ming Dynasty.

Modification of epidermal growth factor-like repeats with O-fucose. Molecular cloning and expression of a novel GDP-fucose protein O-fucosyltransferase

The O-fucose modification is found on epidermal growth factor-like repeats of a number of cell surface and secreted proteins. O-Fucose glycans play important roles in ligand-induced receptor signaling. For example, elongation of O-fucose on Notch by the beta1,3-N-acetylglucosaminyltransferase Fringe modulates the ability of Notch to respond to its ligands. The enzyme that adds O-fucose to epidermal growth factor-like repeats, GDP-fucose protein O-fucosyltransferase (O-FucT-1), was purified previously from Chinese hamster ovary (CHO) cells. Here we report the isolation of a cDNA that encodes human O-FucT-1. A probe deduced from N-terminal sequence analysis of purified CHO O-FucT-1 was used to screen a human heart cDNA library and expressed sequence tag and genomic data bases. The cDNA contains an open reading frame encoding a protein of 388 amino acids with a predicted N-terminal transmembrane sequence typical of a type II membrane orientation. Likewise, the mouse homolog obtained from an expressed sequence tag and 5'-rapid amplification of cDNA ends of a mouse liver cDNA library encodes a type II transmembrane protein of 393 amino acids with 90.4% identity to human O-FucT-1. Homologs were also found in Drosophila and Caenorhabditis elegans with 41.2 and 29.4% identity to human O-FucT-1, respectively. The human gene (POFUT1) is on chromosome 20 between PLAGL2 and KIF3B, near the centromere at 20p11. The mouse gene (Pofut1) maps near Plagl2 on a homologous region of mouse chromosome 2. POFUT1 gene transcripts were expressed in all tissues examined, consistent with the widespread localization of the modification. Expression of a soluble form of human O-FucT-1 in insect cells yielded a protein of the predicted molecular weight with O-FucT-1 kinetic and enzymatic properties similar to those of O-FucT-1 purified from CHO cells. The identification of the gene encoding protein O-fucosyltransferase I now makes possible mutational strategies to examine the functions of the unusual O-fucose post-translational modification.

Suppression of tumor necrosis factor-mediated apoptosis by nuclear factor kappaB-independent bone morphogenetic protein/Smad signaling

The activation of nuclear factor kappaB (NF-kappa B) plays a pivotal role in the regulation of tumor necrosis factor (TNF)-mediated apoptosis. However, little is known about the regulation of TNF-mediated apoptosis by other signaling pathways or growth factors. Here, unexpectedly, we found that bone morphogenetic protein (BMP)-2 and BMP-4 inhibited TNF-mediated apoptosis by inhibition of caspase-8 activation in C2C12 cells, a pluripotent mesenchymal cell line that has the potential to differentiate into osteoblasts depending on BMP stimulation. Utilizing both a trans-dominant IkappaBalpha inhibitor of NF-kappaB expressed in C2C12 cells and IkappaB kinase beta-deficient embryonic mouse fibroblast, we show that BMP-mediated survival was independent of NF-kappaB activation. Rather, the antiapoptotic activity of BMPs functioned through the Smad signaling pathway. Thus, these findings provide the first report of a BMP/Smad signaling pathway that can inhibit TNF-mediated apoptosis, independent of the prosurvival activity of NF-kappaB. Our results suggest that BMPs not only stimulate osteoblast differentiation but can also promote cell survival during the induction of bone formation, offering new insight into the biological functions of BMPs.

[Screening of aberrant genes of immunocytes in severely scalded rats by inhibition of subtractive hybridization]

OBJECTIVE

To explore the relationship between the postburn changes of gene expression of immunocytes and postburn immunological functional disturbance in severely scalded rats.

METHODS

Immunocytes of female F344 rats with severe scalding were harvested and the mRNA was extracted for the inhibition of the expression of aberrant gene selected by subtractive hybridization in contrast to that before scalding. The aberrant genes were cloned and sequenced and compared to those in Genebank for homology.

RESULTS

The harvested immunocytes were identified by LM to be monocytes and lymphocytes. Multiple strips located at 200 approximately 400 bp were obtained by inhibiting subtractive hybridization and were cloned into PGEM-T easy plasmid vector. Thus the genebank of aberrant expression was constructed. Twenty clones were sequenced randomly and partial obtained known genes were in accord with postburn systemic changes. Several novel genes were accepted and registered by Genebank.

CONCLUSION

There exhibited change in the gene expression of peripheral immunocytes at early postburn stage in rats inflicted by severe burn.

Identification of alkylidene hydrazides as glucagon receptor antagonists

High throughput screening of our small molecule combinatorial library identified a class of benzoylnaphthalenehydrazones with modest affinity for the human glucagon receptor. Optimization of this initial hit through a series of targeted libraries and traditional medicinal chemistry led to ligands with nanomolar affinities. Pharmacological evaluation demonstrated that these ligands were competitive glucagon receptor antagonists. Intravenous administration of a representative benzoylnaphthalenehydrazone into rats attenuated glucagon-stimulated glucose levels.

Expression of inflammatory cytokines and beta-defensin 1 mRNAs in porcine epithelial rests of Malassez in vitro

In the present study, we investigated the mRNA expression of inflammatory cytokines, including interleukin (IL)-1 alpha, IL-6, IL-8, and granulocyte macrophage colony-stimulating factor (GM-CSF), and beta defensin 1 (BD-1), an antimicrobial peptide, in the epithelial rests of Malassez in vitro. A reverse transcription-polymerase chain reaction (RT-PCR) assay was performed in order to observe the expression of these mRNAs. The effect of lipopolysaccharide (LPS) on the mRNA expression was also studied by quantitative RT-PCR assay, with a LightCycler, using the double-stranded DNA dye SYBR Green I. The mRNAs of the four kinds of inflammatory cytokines and BD-1 were detected in the epithelial cells under normal culture conditions. Immunocytochemical staining showed the expression of CD14, a receptor for LPS, on the epithelial cells. The mRNA expressions of IL-1 alpha, IL-6, IL-8, and GM-CSF were upregulated by stimulation with LPS, in a dose- and time-dependent manner. Epithelial cells incubated with 1000 ng/ml of LPS for 6 h showed the most significant upregulation of the cytokine mRNAs. On the other hand, no obvious alteration of BD-1 expression by LPS stimulation was observed. The results indicated that the epithelial rests of Malassez may actively participate in the inflammatory response to bacterial infection, and that they play an important role in the defense mechanism of the radicular cyst.

[Screening and characterization of human phage antibody to hepatitis virus C NS5A antigen]

OBJECTIVE

To screen and characterize human phage antibody against hepatitis C virus (HCV)NS5A antigen.

METHODS

The recombinant phages were panned by recombinant HCV NS5A antigen which was coated in a microtiter plate; after five rounds of biopanning, 35 clones were obtained and demonstrated specific to NS5A antigen. The specific binding capacity of the ScFv antibody to HCV NS5A antigen was determined by ELISA.

RESULTS

HCV NS5A phage antibody had a specific combination capacity with hepatitis C virus NS5A antigen. The DNA sequence data showed that the ScFv gene was composed of 789 bp and codes for a peptide of 262 amino acid residues.

CONCLUSIONS

Human single chain antibody to hepatitis C virus NS5A antigen has been identified by means of the phage display technology.

[Screening and characterization of human phage antibody to hepatitis C core antigen]

OBJECTIVE

To screen and characterize human phage antibody (ScFv) against hepatitis C core antigen.

METHODS

The recombinant phages were panned by core antigen that was coated in a microtiter plate. After three rounds of biopanning, 48 clones were determined specific to core antigen. The specificity of each ScFv colone was determined by ELISA. The coding gene for HCV protein ScFv has been sequenced.

RESULTS

Phage antibody for HCV core protein had a specific combination character with core antigen of hepatitis C virus. The DNA sequence data showed that the ScFv gene included 774 bp.

CONCLUSIONS

Human single chain antibody to hepatitis C core antigen has been identified by means of the phage display technology.

[Characteristics of N2O emissions from vegetal soils on Fildes peninsula, Antarctica]

The N2O fluxes from the vegetal soils were first measured on the Fildes peninsula, Antarctica, and the total N2O emission was also estimated in the summer 2 months. The daily variations of N2O fluxes appeared single-peak trend under the sunshine or rainy weather conditions but they were irregular under the snow weather conditions and inconsistent with the atmospheric temperatures. The seasonal variations of the N2O fluxes were affected by the temperature and rainfall. The conditions during the transitions between dry and wet seasons improved the N2O emission. The total N2O emissions from moss and lichen soils were 3.7152 kg and 2.5344 kg, respectively. It follows that the vegetal soils are the sources for the atmospheric N2O on the Fildes peninsula, Antarctica.

Three-dimensional finite element analyses of four designs of a high-strength silicon nitride implant

The effects of implant shape and size on the stress distribution around high-strength silicon nitride implants under vertical and oblique forces were determined using a three-dimensional finite element analysis. Finite element models were designed using as a basis the serial sections of the mandible. Using Auto-CAD software, the model simulated the placement of implants in the molar region of the left mandible. Results of the analyses demonstrated that mainly the implant root shape and the directions of bite forces influence the stress distributions in the supporting bone around each implant. Implant size is a lesser factor. The serrated implants presented a larger surface area to the bone than either the cylindrical or tapered implants, which resulted in lower compressive stress around the serrated implants. With increasing implant diameter and length, compressive stress decreased. The mean compressive stress distribution on the serrated implants was more flat (platykurtic) than on either the cylindrical or tapered implants. Results of studies on two load directions (vertical and oblique) showed that, in either case, the compressive stress in the cortical bone around the neck of the implant was higher than in the cancellous bone along the length of the implant. The most extreme principal compressive stress was found with oblique force. This study provides the first information on the relationship between shape of the silicon nitride implant and stress on the supporting bone.