Archives of Oral Biology

Aims & Scope/Editorial Board

2012-05-01

Green tea: A promising natural product in oral health

Baruch Narotzki, Abraham Z. Reznick, Dror Aizenbud, Yishai Levy — 2012-05-01

Abstract: Green tea is a leading beverage in the Far East for thousands of years; it is regarded for a long time as a health product. Green tea is important source of polyphenol antioxidants. Polyphenols including epigallocatechin 3 gallate (EGCG) constitute the most interesting components in green tea leaves. Green tea has the potential to protect against various malignant, cardiovascular and metabolic diseases. There is a growing body of evidence pointing a beneficial role of green tea and its polyphenols in oral health. Green tea protects against bacterial induced dental caries. Tea polyphenols possess antiviral properties, believed to help in protection from influenza virus. Additionally, green tea polyphenols can abolish halitosis through modification of odorant sulphur components. Oral cavity oxidative stress and inflammation, consequent to cigarette smoking and cigarettes’ deleterious compounds nicotine and acrolein, may be reduced in the presence of green tea polyphenols. Generally, green tea defends healthy cells from malignant transformation and locally has the ability to induce apoptosis in oral cancer cells. All together, there is an increasing interest in the health benefits of green tea in the field of oral health. Nonetheless, there is still a need for more clinical and biological studies to support guidelines for green tea intake as part of prevention and treatment of specific oral pathologies.

Ultrastructural and proteomic alteration of superficial masseter muscle after lower jaw sagittal advancement in rat

Dongqing Zhou, Yuxing Bai, Xiaoxia Che — 2012-05-01

Abstract: Objective: The purpose of this study was to investigate the ultrastructural and proteomic alteration of the superficial masseter muscle (SM) after lower jaw sagittal advancement in a rat model.Methods: Six 35-day-old male Sprague-Dawley rats were utilized in a transmission electron microscopy study, and six more in a proteomic study. The rats were randomly allocated to two experimental and two control groups (n=3). The experimental groups were fitted with fixed devices that protruded the mandible, whereas the control groups were not fitted with the devices. The rats were sacrificed 3 days after mandibular advancement. Transmission electron microscopy analysis, Western blot analysis, comparative proteomic analysis, and matrix-assisted laser desorption/ionization-time-of-flight (MALDI-TOF) mass spectrometry (MS) were applied to profile qualitative and quantitative differences in the morphology and proteome of rat SM.Results: Under the transmission electron microscope, morphological changes of the SM were associated with deregulation of the myofibrillar network accompanied by fibre rupture, interlaced myofilaments, and changes in the mitochondria and sarcoplasmic reticulum cisternae. The shape of mitochondria changed. Proteomic analysis identified fourteen differentially expressed proteins involved in metabolism, contraction or the cytoskeleton, and transport. Amongst these, the expression of 13 proteins increased and 1 decreased. According to Western blot analysis, myosin heavy chain II was down-regulated.Conclusion: Three days after functional mandibular advancement, the ultrastructure of rat SM had changed. This change paralleled changes in metabolic, contractile and cytoskeletal, and transport proteins, which affected SM physiology. The energy metabolism of SM increased, and the muscle velocity and force of contraction decreased.

Recombinant bone morphogenetic protein-2 induces up-regulation of vascular endothelial growth factor and interleukin 6 in human pre-osteoblasts: Role of reactive oxygen species

2012-05-01

Abstract: Objective: Bone morphogenetic proteins (BMPs) and vascular endothelial growth factor (VEGF) have been reported in many studies to play a major role in the communication between endothelial cells and osteoblasts. The inflammatory reaction and relative hypoxia at the site of bone injury are the first stages of the fracture repair. rhBMP-2 has been used extensively in spinal fusion and reconstruction of maxillofacial bone defects with main complication is the formation of seroma. The aim of this study was to test whether rhBMP-2 regulates the expression of the angiogenic and inflammatory mediators in pre-osteoblasts via generating reactive oxygen species (ROS).Methods: rhBMP-2 effect on angiogenesis and inflammatory genes was assessed using normal human osteoblasts (NHOst). Angiogenesis genes were measured using angiogenic PCR array. VEGF and IL6 production were analysed using ELISA kit and real-time PCR. ROS production was assessed using dihydroethidine and dichlorofluorescein staining and lipid peroxidation. HIF-1α immunoreactivity was performed using immunofluorescence staining.Results: There was an increase in the pro-angiogenic and -inflammatory genes as well as VEGF and IL6 protein expression in NHOst by rhBMP-2. This increase in VEGF and IL6 was blocked by the ROS scavenger N-acetyl cysteine (NAC).Conclusion: The regulatory effect of rhBMP-2 on angiogenesis and inflammation is mediated through a ROS-dependent mechanism, which involves upregulation of crucial angiogenic and inflammatory mediators such as VEGF and IL6. These findings highlight the need for future studies to identify new therapeutic targets downstream from rhBMP-2 to potentiate its beneficial effect or limit its complications such as seroma formation.

1α,25-Dihydroxyvitamin D3 inhibits osteoblastic differentiation of mouse periodontal fibroblasts

2012-05-01

Abstract: Objective: Periodontal ligament (PDL) is a non-mineralized tissue connecting cementum and alveolar bone. Recent studies have suggested that periodontal fibroblasts can differentiate into mineralized tissue-forming cells such as osteoblasts and cementoblasts. We elucidated the immunolocalization of vitamin D receptor (VDR) and the effects of vitamin D3 (VD3) on mouse periodontal fibroblasts to clarify the role of VDR and VD3 in the differentiation of periodontal fibroblasts.Design: Immunohistochemical analysis using anti-VDR antibody was performed in paraffin sections of mouse mandibles at E13, E14, E17, P10, and P35. The roles of VD3 in osteoblastic differentiation and mineralization were estimated by alkaline phosphatase (ALP) and alizarin red (AR) staining. In addition, the mRNA expression of osteoblast markers and mineralization inhibitors was examined by real-time PCR.Results: At the bud, cap and early bell stages, immunoreactivity for VDR was scarcely seen in the cells of dental follicles. Labelling was detected in the nuclei of cemetoblasts, periodontal fibroblasts and osteoblasts during root formation. VD3 inhibited ALP activity and AR-positive mineralized nodule formation of periodontal fibroblasts in osteogenic culture medium. Real-time PCR revealed that VD3 down-regulated the levels of osteoblast markers. In contrast, VD3 significantly up-regulated the level of periodontal ligament associated protein (PLAP)-1, a negative regulator of osteoblastic differentiation.Conclusion: These results suggest that VD3 negatively regulates the osteoblastic differentiation of mouse periodontal fibroblasts and prevents the periodontal ligament from mineralization via increase of PLAP-1.

The optimal dose of recombinant human osteogenic protein-1 enhances differentiation of mouse osteoblast-like cells: An in vitro study

2012-05-01

Abstract: Objective: There is no certain conclusion on the effect of recombinant human Osteogenic Protein-1 (OP-1, BMP-7) on the proliferation of the osteoblast-like cell line, MC3T3-E1. Furthermore, the optimal dose of rhOP-1 on cell differentiation still needs to be elucidated. This investigation aims to delineate the biofunctional characteristics of rhOP-1 in inducing osteoblastogenesis of MC3T3-E1 through in vitro time-course and dose–response studies.Design: MC3T3-E1 cells were cultured for 1, 4, 7 days with the addition of different rhOP-1 concentrations (0, 10, 20, 50, 100, 200, 400ng/ml), and cell proliferation and cell differentiation were examined.Results: MC3T3-E1 cell proliferation was stimulated by rhOP-1 in a dose-dependent manner (0–400ng/ml) on day 1, whereas on day 4 and 7, it was still stimulated at low concentrations (10, 20, 50ng/ml) but inhibited at high ones (200, 400ng/ml). The alkaline phosphatase (ALP) activity, osteocalcin (OC) production, collagen deposition and extracellular matrix mineralization were dramatically elevated by rhOP-1 treatment, as a function of culture time and rhOP-1 concentration, and all of them reached a plateau at the concentration of 200ng/ml. Real-time quantitative RT-PCR results showed Runx2, AKP-2, OC and Nog mRNA expressions increased in a dose- and time-dependent manner, and their expressions were significantly higher at high rhOP-1 concentrations than that of low ones. No significant differences were found between the effects of 200ng/ml rhOP-1 and 400ng/ml rhOP-1 on the differentiation of MC3T3-E1 cells, except the expression of Nog mRNA, whose expression level was much higher at 400ng/ml than that at 200ng/ml.Conclusions: These results suggest that cell proliferation of MC3T3-E1 is depended on culture time and rhOP-1 concentration, rhOP-1 could stimulate the differentiation of MC3T3-E1 cells and the optimal concentration could be 200ng/ml.

Demineralised human dentine matrix stimulates the expression of VEGF and accelerates the bone repair in tooth sockets of rats

2012-05-01

Abstract: Objective: In this study we investigated the possible use of human demineralised dentine matrix (DHDM), obtained from the extracted teeth, as bone graft material and evaluated the expression of vascular endothelial growth factor (VEGF) induced by this material in the healing process of tooth sockets of rats.Design: To evaluate bone regeneration and expression of VEGF induced by DHDM, thirty-two male Wistar rats weighing approximately 200g were used. After maxillary second molar extraction, the left sockets were filled with DHDM and the right sockets were naturally filled by blood clot (control). The animals were sacrificed at 3, 7, 14 and 21 days after surgery and upper maxillaries were processed for histological, morphometric and immunohistochemical analyses. DHDM was used to evaluate the mechanical effect of bone graft material into sockets. Expression of VEGF was determined by immunohistochemistry in all groups.Results: Our results demonstrated a significant increase in the newly formed bone tissue in sockets of 7, 14 and 21 days and a significant increase in VEGF expression at days 7 and 14 on treated sockets.Conclusions: Our results showed that DHDM increases the expression of VEGF and accelerates the healing process in rats tooth sockets, by stimulating bone deposition and also vessels formation. These results suggest that DHDM has osteoinductive/osteoconductive potential and may represent an efficient grafting material on guided bone regeneration.

The influence of chronic stress imposed on pregnant rats on the induced bone loss in their adult offspring

2012-05-01

Abstract: Background and objective: Stress during pregnancy may alter offspring susceptibility to diseases during adulthood. In the present study, female Lewis rats were subjected to chronic stress during the gestational period, and the effect of this stress was evaluated histometrically on the progression of ligature-induced bone loss in their adult offspring.Material and methods: After confirming pregnancy, half of the pregnant rats were randomly designated as control animals (no stress regimen was imposed), and the other half was submitted to a chronic stress model (immobilization at cold temperature) between the 7th and the 18th gestational day. After birth, 12 male rats delivered by stressed mothers – Group 1 (G1) – and 12 male rats delivered by non-stressed mothers – Group 2 (G2) – were selected. When birthed rats reached 250g of body weight, a silk ligature was placed around their maxillary right second molar in order to induce bone loss. The non-ligated left side served as a control. Sixty days later, these animals were sacrificed by anaesthetic overdose. After routine laboratorial processing, images of the histological sections were digitized and submitted for histometric measurement using two parameters: histological attachment loss and bone loss.Results: On the ligated side, G1 presented with greater histological attachment and bone loss than G2 (p<0.05). On the non-ligated control side, neither of the groups presented with alterations in these parameters (p>0.05).Conclusion: The chronic stress regimen imposed on pregnant rats produced a greater progression of ligature-induced bone loss in their adult offspring.

Nicotine up-regulates IL-8 expression in human gingival epithelial cells following stimulation with IL-1β or P. gingivalis lipopolysaccharide via nicotinic acetylcholine receptor signalling

2012-05-01

Abstract: Objective: Cigarette smoking is an important risk factor for periodontal disease. The aim of this study is to evaluate the effect of nicotine, a major component of cigarette smoke, on interleukin-8 (IL-8) production and cellular signalling via nicotinic acetylcholine receptors (nAChRs) in human gingival epithelial cells (HGECs).Design: Messenger RNA (mRNA) expression of nAChR subunits in three different HGEC lines (epi 4, Tfx and E6E7) was assessed using reverse transcription-polymerase chain reaction (RT-PCR). HGECs were stimulated by 1×10−3M nicotine in the presence or absence of IL-1β or Porphyromonas gingivalis lipopolysaccharide (LPS). IL-8 production was then examined using real-time PCR and enzyme-linked immunosorbent assay. Nicotine-mediated signalling in the epi 4 cell line was also evaluated by Western blotting.Results: HGECs expressed several nAChR subunits. Nicotine increased the secretion of IL-8 from HGECs that were cultured in the presence of IL-1β or P. gingivalis LPS and also induced the phosphorylation of extracellular signal-regulated kinase (ERK) in epi 4. Pretreatment with non-selective nAChR antagonist or intracellular calcium chelator reduced the nicotine-induced phosphorylation of ERK. Furthermore, nicotine-induced IL-8 secretion was decreased by pretreatment with non-selective nAChR antagonist, ERK1/2 inhibitor or intracellular calcium chelator.Conclusion: These findings indicate that nicotine increases IL-8 production in gingival epithelial cells via ERK phosphorylation following Ca2+ signalling after nAChR activation.

Association of interferon-gamma gene polymorphisms with susceptibility to oral lichen planus in the Thai population

2012-05-01

Abstract: Objective: Interferon-gamma (IFN-γ) is highly expressed in oral lichen planus (OLP). The IFN-γ (+874 in intron 1, rs2430561) TT genotype, which has been reported to be associated with high IFN-γ production, was hypothesized to be associated with susceptibility to OLP in the Thai population.Design: Genomic DNA samples from 74 OLP and 268 healthy controls were evaluated for IFN-γ polymorphisms by polymerase chain reaction with sequence-specific primers (PCR-SSP) and direct sequencing method.Results: The T allele was significantly associated with an increased risk of OLP development as compared to the A allele (OR=1.76, P=0.004; Pc=0.02). The effect of the T allele was similar to an autosomal recessive disorder; the presence of TT genotype (when compared to AA and AT) conferred an OR of 2.61, P=0.008; Pc=0.04.Conclusions: We found an association between IFN-γ +874A/T polymorphism and susceptibility to OLP. However, an association study utilising a larger sample size and patients from other races apart from the Asian population should be performed to further verify these findings.

Differential expression of TLR-2 and TLR-4 in the epithelial cells in oral lichen planus

2012-05-01

Abstract: Objective: Oral lichen planus (OLP) is a chronic inflammatory condition of the mucosa mediated by a complex signalling network between the keratinocytes and the sub-epithelial lymphocytes. Since OLP occurs in constantly renewing epithelium continuously exposed to commensals, we hypothesised that the epithelial cell microflora interactions may mediate the persistent inflammation. By virtue of their ability to respond to most oral commensal microorganisms, the toll like receptor-2 (TLR-2) and TLR-4 are the most widely investigated receptors in oral diseases. The overall objective of this study was to investigate the role of TLR-2 and TLR-4 in OLP.Design: Systemically healthy OLP and control subjects were recruited after obtaining the institutional review board approval. Expression of TLR-2 and TLR-4 proteins and transcripts in the tissue epithelium and in the epithelial cells isolated from saliva were determined by immunohistochemistry and quantitative real-time polymerase chain reaction respectively.Results: The tissue epithelium and the salivary epithelial cells expressed reduced TLR-2 and increased TLR-4 proteins and transcripts in OLP. The salivary epithelial cells from OLP subjects secreted elevated IL-12. However, upon stimulation with bacterial lipopolysaccharide the epithelial cells from OLP exhibited a mixed Th1 (IL-12) and Th2 (IL-4) response. Presence of dexamethasone significantly reduced inflammatory cytokines in the in vitro stimulated cultures of salivary epithelial cells from OLP subjects.Conclusion: Collectively, our data support a critical role for the host–microbial interactions in the OLP pathogenesis. The potential use of exfoliated oral epithelial cells in saliva for functional analysis exponentially increases its value as biological specimen for clinical research.

Assessment of clinicopathological characteristics and immunoexpression of COX-2 and IL-10 in oral pyogenic granuloma

2012-05-01

Abstract: Objective: The aim was to investigate the relationship between patient clinical background, histological features, and immunoexpression of COX-2 and IL-10 in oral pyogenic granuloma (PG).Design: Paraffin-embedded samples of oral PG (n=57) were prepared for histological and immunohistochemical assessment. Based on the histological features, the samples were categorised into lobular capillary hemangioma (LCH) and non-LCH subtypes. The epithelial lining, angiogenic index, inflammatory infiltrate density, and interstitial fibrosis, were assessed in haematoxylin–eosin stained sections. In addition, the marker expression estimation (stained cells/total cell number) was used to assess immunoreactivity for each sample.Results: Although there were no significant differences between histological subtypes regarding demographic and clinical parameters, mean values of microvessel count and inflammatory infiltrate density were significantly greater in the non-LCH PG subtype. Also, whilst cellular immunolocalisation patterns of COX-2 and IL-10 were similar, mean values of expression estimation of each immunomarker were significantly higher in non-LCH PGs in comparison with LCH subtypes. Furthermore, significant variations for immunohistochemical parameters were evident regarding to angiogenic index and inflammatory infiltrate density, but not concerning demographic and clinical data. Finally, linear regression analysis showed a significant positive correlation between the expression estimation of the two immunomarkers.Conclusion: These findings suggest a role for COX-2 and IL-10 in the etiopathogenesis of oral PG and indicate that LCH and non-LCH histological subtypes represent different stages in the evolution of a single lesion with varying degrees of proliferative, angiogenic, and inflammatory activity.

An unlikely role for the NAT2 genotypes and haplotypes in the oral cancer of south Indians

Lakshmi Balaji, Balaji Singh Krishna, Bhaskar L.V.K.S. — 2012-05-01

Abstract: The arylamine N-acetyltransferase 2 (NAT2) enzyme detoxifies a wide spectrum of naturally occurring xenobiotics including carcinogens and drugs. Acetylation catalysed by the NAT2 is an important process in metabolic activation of arylamines to electrophilic intermediates that initiate carcinogenesis. Polymorphism in N-acetyltransferase 2 gene was reported to be associated with the susceptibility of various cancers.Objective: The aim of our study was to determine whether there is any association between the susceptibility to oral cancer amongst the variations of NAT2 genotypes.Design: This study was carried out in 157 patients with oral cancer. The control group consisted of 132 healthy volunteers. The most common polymorphisms rs1799929, rs1799930 and rs1799931 on the NAT2 gene were screened for the genotypes using TaqMan allelic discrimination.Results: All the three SNPs were polymorphic with minor allele frequency of 0.339, 0.372 and 0.061 for rs1799929, rs1799930 and rs1799931, respectively. None of the polymorphic site deviated from HWE in controls. There were no significant differences in genotype or allele frequencies of three SNPs between controls and cases with oral cancer. Risk of oral cancer development for the carriers of the individual deduced phenotypes was also not statistically significant. Of the 3 studied polymorphisms, 2 were in strong LD and form one haplotype block. None of the haplotype had shown significant association with the oral cancer.Conclusions: Our study concludes that the NAT2 genotypes, phenotypes and haplotypes are not involved in the susceptibility to oral cancer in South Indian subjects.

The effect of IL-1 receptor antagonist on orthodontic tooth movement in mice

2012-05-01

Abstract: Objective: Orthodontic tooth movement (OTM) is achieved by alveolar bone remodelling induced by mechanical loading. Whilst interleukin-1 (IL-1) is directly involved in OTM, the role of interleukin-1 receptor antagonist (IL-1Ra), a naturally occurring IL-1 antagonist, is not completely defined. Therefore, the aim of this study was to investigate the effects of IL-1Ra on OTM.Methods: An orthodontic appliance was placed in C57BL6 mice treated with vehicle or IL-1Ra (10mg/kg/day). OTM and TRAP-positive osteoclasts were evaluated after 12 days of mechanical loading and the levels of cytokines on periodontal tissues were analysed by ELISA after 12 and 72h.Results: Mice treated with IL-1Ra showed diminished OTM and decreased numbers of TRAP-positive osteoclasts. In line with this, lower levels of IL-1β and TNF-α, and higher levels of IL-10, were observed on periodontal tissues of IL-1Ra-treated mice in relation to the vehicle-treated group.Conclusion: The present study suggests that IL-1Ra downregulates OTM, probably by its anti-inflammatory actions.

In situ remineralisation of eroded enamel lesions by NaF rinses

2012-05-01

Abstract: Objective: The purpose of this pilot study was to evaluate the remineralisation of eroded enamel by NaF rinses in an intra-oral model.Methods: Serving as their own control, subjects (N=80) participated in a randomised, four-leg (20 subjects/leg), 28-day, parallel design study. In each leg, each participant wore a customised orthodontic bracket attached to a mandibular molar that contained one tooth block having an initial erosive lesion (0.3% citric acid, pH 3.75, 2h). Within the 28-day period, participants engaged in twice-daily brushing for 1min with a fluoride-free dentifrice followed by 1-min rinsing with one of the following aqueous rinses: fluoride-free (0ppm F), 225ppm F, 225ppm F plus functionalised β-tricalcium phosphate (fTCP), and 450ppm F. Following intra-oral exposure, appliances were removed and specimens were analysed using surface microhardness (SMH) and transverse microradiography (TMR).Results: Statistically significant (p<0.05) remineralisation, as determined by SMH and TMR, of the eroded enamel relative to baseline occurred for each fluoride system. No significant differences in SMH were observed amongst the fluoride groups (p>0.05), however, 225ppm plus fTCP produced 27% and 7% SMH indent length reduction relative to 225ppm F and 450ppm F, respectively. No significant differences in TMR were observed amongst the fluoride groups (p>0.05), however, 225ppm F plus fTCP and 450ppm F produced significant (p<0.05) mineral gains relative to the fluoride-free control, whilst 225ppm F did not (p>0.05). Relative to the 225ppm F group, the 450ppm F and 225ppm F plus fTCP groups produced 65% and 61% greater mineral change, respectively.Conclusions: These pilot results demonstrate this model is sensitive to fluoride and that addition of fTCP to an aqueous rinse containing 225ppm F may provide significant remineralisation benefits. Therefore, the combination of relatively low levels of fluoride and fTCP might be an effective alternative to a high fluoride treatment for anti-erosion benefits.

Analysis of syndecan-1 gene promoter during mouse tooth development

Hitomi Iguchi-Ishiguro, Yasuo Ouchi, Sumiko Watanabe, Yukihiro Numabe — 2012-05-01

Abstract: Objective: Syndecan-1 plays an important role in cell proliferation in dental papilla during tooth development. This study aimed to clarify the transcription mechanisms that regulate syndecan-1 gene expression in dental papilla.Design: We analysed genomic conservation and putative transcriptional factor binding sites of syndecan-1 gene loci using the bioinformatics tool VISTA. To identify the region responsible for syndecan-1 gene expression in mouse dental papilla cells (MDPCs) in vitro, the 1.5-kb upstream region of the mouse syndecan-1 coding region was inserted upstream of the enhanced green fluorescent protein (EGFP) or luciferase gene, and promoter activity was examined by transient reporter gene expression assay in cultured MDPCs. To examine the binding of the upstream binding factor, we performed chromatin immunoprecipitation (ChIP) assay.Results: VISTA analysis showed that the 1.5-kb upstream region was highly conserved amongst species, and three GC-rich motifs, as well as a TATA-box-like motif, were identified in this region. Reporter gene assay showed that the 1.5-kb upstream region of mouse syndecan-1 induced reporter gene expression in MDPCs. Deletion of the promoter from the 5′-end to 339bp upstream reduced luciferase activity by nearly half vs. the 1.5-kb sequence. Further deletion up to 68bp resulted in further loss of luciferase activity. On ChIP assay, we found direct recruitment of Sp3 transcription factor to the GC-rich motif region.Conclusion: The 1.5-kb upstream region of the syndecan-1 gene was sufficient to induce its expression in dental papilla, and binding of Sp3 transcription factor may play a pivotal role in this syndecan-1 induction.

Isolation and characterization of probiotic strains for improving oral health

2012-05-01

Abstract: Probiotics have been proven effective for preventing caries. In contrast, the effect of probiotics on improving oral diseases such as gingivitis, periodontitis and halitosis has been less explored.Objective: To perform a screening of lactic acid bacteria, according to international guidelines for the evaluation of probiotics, in order to select candidate probiotic strains for preventing oral disorders.Study design: The strains were isolated from healthy children and were subjected to a variety of in vitro tests in order to show their functionality. The safety of the strains was assessed by determining antibiotic susceptibility and production of lactic acid.Results: Forty-six of the 100 new isolates were assigned to lactic acid bacteria genera after a biochemical characterization. Most of the new isolated strains seem to be resistant to oral conditions, have great ability to form aggregates and have high antagonistic activity against oral pathogens. None of the strains produced unpleasant volatile compounds. The strains showed high ability to adhere to oral tissues and they do not present any antibiotic resistance. Moreover, an increased risk of developing caries due to their ability to produce lactic acid was discarded in seven pre-selected probiotic candidates.Conclusions: These lactic acid bacteria show promising properties to be used as potential probiotics for improving oral health.

Antimicrobial and antibiofilm action of Casbane Diterpene from Croton nepetaefolius against oral bacteria

2012-05-01

Abstract: Objective: The antibacterial activity of Casbane Diterpene (CD) was evaluated in vitro against Streptococcus oralis, S. mutans, S. salivarius, S. sobrinus, S. mitis and S. sanguinis. The viability of planktonic cells was analysed by susceptibility tests (MIC and MBC) and antibiofilm action was assayed.Methods: The minimal inhibitory and bactericidal concentrations (MIC and MBC) of oral Streptococcus were evaluated through microdilution tests. To assay antibiofilm activity, biofilms were generated on 96-wells polystyrene plates under the presence of CD and quantified by a crystal violet technique and colonies forming units counting.Results: The CD isolated from Croton nepetaefolius showed antimicrobial effect on planktonic forms and biofilms of oral pathogens, with MIC values of 62.5μg/mL against Streptococcus oralis and values between 125 and 500μg/mL against S. mutans, S. salivarius, S. sobrinus, S. mitis and S. sanguinis. CD showed an inhibitory effect on S. mutans biofilm formation at 250μg/mL, and a decrease on viable cell of 94.28% compared to the normal biofilm growth.Conclusions: The compound CD can be considered as a promising molecule for the treatment against oral pathogens responsible for dental biofilm.

Variability of human saliva composition: Possible relationships with fat perception and liking

Eric Neyraud, Olivier Palicki, Camille Schwartz, Sophie Nicklaus, Gilles Feron — 2012-05-01

Abstract: Saliva is the medium that bathes the taste receptors in the oral cavity and in which aroma and taste compounds are released when food is eaten. Moreover saliva contains enzymes and molecules that can interact with food. To date, little research has been devoted to the intra- and inter-individual variabilities of these components and their inter-relationships. The first aim of this work was to study intra- and inter-individual variabilities over time in the composition of molecules likely to interact with food in the mouth, with particular focus on molecules that might interact with fat. The second aim was to try to relate this composition to a liking for fat and its perception. Stimulated and unstimulated saliva from 13 subjects was collected in the morning and afternoon on three occasions at 4-month intervals. Saliva characteristics such as flow, protein concentration, lipolysis, proteolysis, amylolysis, lipocalin concentration, lysozyme activity, total antioxidant status and uric acid concentrations were measured, as well as the liking for and perceived fattiness of a fat solution. The results showed that for most of the measured characteristics, intra-subject variability in saliva composition was smaller than inter-subject variability, with remarkable stability over time (8 months) in terms of flow, lypolysis, proteolysis and total antioxidant status. Relationships were found between some of these characteristics (lipolysis, lipocalin and flow) and fat-liking or perception, showing that the composition of saliva may play an important role in fat perception and liking.

The actin-specific reagent jasplakinolide induces apoptosis in primary rat parotid acinar cells

2012-05-01

Abstract: Jasplakinolide is a reagent that stabilizes and polymerizes actin filaments and is a commonly used tool in cell biology. In primary rat parotid acinar cells, jasplakinolide partially inhibited the release of amylase induced by β-adrenergic receptor activation, as previously reported. However, in confocal microscopic observation with fluorescence conjugated anti-actin antibody, the jasplakinolide-treated cells not only showed decreased fluorescence intensity and aggregation of cortical F-actin but also revealed events characteristic of apoptosis such as cell shrinkage, membrane blebbing and apoptotic body formation. Such characteristic events of apoptosis were confirmed by transmission electron microscopy. The occurrence of apoptosis in jasplakinolide-treated cells was further confirmed by biochemical analysis: a DNA ladder was detected by electrophoresis, and DNA fragmentation was revealed using ELISA with an antibody to single-stranded DNA. Moreover, the degradation of fodrin was detected in jasplakinolide-treated cells by Western blotting, and the K+ release induced by the fluid secretagogue carbachol was impaired. Taken together, these results demonstrate that jasplakinolide induces apoptosis and suppresses the secretory functions of rat parotid acinar cells.

Determination of leucocyte subsets in human saliva by flow cytometry

2012-05-01

Abstract: Objective: Validation of a flow cytometry-based method for the determination of major leucocyte subsets [polymorphonuclear (PMN) cells, monocytes, T cells and B cells] in paraffin-stimulated whole human saliva.Design: Salivary leucocyte subsets were determined by four-colour flow cytometry in eight healthy volunteers on three consecutive days. Comparison of leucocyte subsets between saliva and whole blood was also performed. Day-to-day variability and intraclass correlation coefficients (ICC) were determined as indicators of assay reliability.Results: It was observed that PMN cells were the predominant cells in the saliva. Percentages of mononuclear cells ranged from 0.3% to 7.2%, with monocytes composing the highest percentage, followed by T cells and B cells. Regardless of high intra-individual day-to-day variability, proportions of leucocyte subsets did not significantly change over three measurements, and high ICCs were calculated for T cells and monocytes.Conclusion: Flow cytometry can be used as non-invasive and reproducible method for the analysis of leucocyte subsets in human saliva. Further investigation of pathological and other conditions that have the potential to influence salivary leucocyte subsets is warranted.