Putrescine (1,4-Diaminobutane) enhances antifungal activity in postharvest mango fruit against Colletotrichum gloeosporioides through direct fungicidal and induced resistance mechanisms.

Anthracnose decay caused by Colletotrichum gloeosporioides greatly shortens the shelf life and commercial quality of mango fruit. Putrescine (1,4-Diaminobutane) is involved in modulating plant defense to various environmental stresses. In this research, in vivo and in vitro tests were used to explore the antifungal activity and the underlying mechanism of putrescine against C. gloeosporioides in mango fruit after harvested. In vivo tests suggested that putrescine markedly delayed the occurrence of disease and limited the spots expansion on inoculated mango fruit. Further analysis exhibited that putrescine treatment enhanced disease resistance, along with enhanced activities of chitinase (CHI), ß-1,3-glucanase (GLU), phenylalanine ammonia-lyase (PAL), cinnamate-4-hydroxylase (C4H), 4-coumarate coenzyme A ligase (4CL), polyphenol oxidase (PPO) and the accumulation of lignin, flavonoid, phenolics, and anthocyanin in infected mango fruit. In addition, in vitro tests showed that putrescine exerted strongly antifungal activity against C. gloeosporioides. Putrescine induced the production of reactive oxygen species (ROS) and severe lipid peroxidation damage in C. gloeosporioides mycelia, resulting in the leakage of soluble protein, soluble sugar, nucleic acids, K+ and Ca2+ of C. gloeosporioides mycelia. The mycelium treated with putrescine showed severe deformity and shrinkage, and even cracking. Taken together, putrescine could effectively reduce the incidence rate and severity of anthracnose disease possibly through direct fungicidal effect and indirect induced resistance mechanism, thus showing great potential to be applied to disease control.

Exogenous Nitric Oxide-Induced Postharvest Gray Spot Disease Resistance in Loquat Fruit and Its Possible Mechanism of Action.

The effectiveness of nitric oxide (NO) for control of grey spot rot cause by Pestalotiopsis eriobotryfolia in harvested loquat fruit and its probable mechanisms have been investigated. The results showed that NO donor sodium nitroprusside (SNP) did not evidently inhibit mycelial growth and spore germination of P. eriobotryfolia, but resulted in a low disease incidence and small lesion diameter. SNP resulted in a higher hydrogen peroxide (H2O2) level in the early stage after inoculation and a lower H2O2 level in the latter period by regulating the activities of superoxide dismutase, ascorbate peroxidase and catalase. At the same time, SNP enhanced the activities of chitinase, ß-1,3-glucanase, phenylalanine ammonialyase, polyphenoloxidase, and total phenolic content in loquat fruit. However, SNP treatment inhibited the activities of cell wall-modifying enzymes and the modification of cell wall components. Our results suggested that NO treatment might have potential in reducing grey spot rot of postharvest loquat fruit.

Treatment Durations and Whitening Outcomes of Different Tooth Whitening Systems.

Background and Objectives: Tooth whitening is a relatively conservative and effective option to treat discolored teeth. However, questions remain whether in-office or at-home tooth whitening products with short treatment durations are as effective and stable as products with longer treatment durations. Materials and Methods: Forty human third molars with intact enamel surfaces were divided into four groups of ten each, subjected to discoloration challenges with coffee for 60 h, and they were treated with four professional tooth whitening systems: two for take-home use-6% hydrogen peroxide for 30 min/d for a total of 7 h in 14 days (HP6), 10% carbamide peroxide for 10 h/d for 140 h in 14 days (CP10), as well as two for in-office use-35% HP for 10 min × 3 (HP35) for a total of 30 min and 40% HP for 20 min × 3 (HP40) for a total of 60 min. Teeth colors were assessed in the CIE L*a*b* color space with a spectrophotometer immediately and six months after whitening treatments. Surface roughness (Sa) for the treated and untreated enamel surfaces of the teeth in all groups were evaluated with a three-dimensional laser scanning microscope after six months. Results: No significant differences were found between HP6 and CP10 groups immediately after whitening (∆E 10.6 ± 1.6 vs. 11.4 ± 1.7, p > 0.05) and at six months after treatments (∆E 9.0 ± 1.9 vs. 9.2 ± 2.5, p > 0.05), or between HP35 and HP40 groups immediately after whitening (∆E 5.9 ± 1.2 vs. 5.3 ± 1.7, p > 0.05) and at six months after treatments (∆E 7.2 ± 1.6 vs. 7.7 ± 1.3, p > 0.05). The two at-home whitening systems achieved significantly better whitening outcomes than the two in-office products immediately after whitening (p < 0.05). However, at six months after treatments, the differences between at-home and in-office treatments had narrowed significantly (p > 0.05). There were no statistically significant differences with respect to the Sa values between the treated and untreated surfaces (p > 0.05). Conclusions: Tooth whitening products in the same product category have similar whitening efficacies, despite significant differences in treatment durations (7 vs. 140 h, and 30 min vs. 60 min, respectively). Take-home products achieved better whitening outcomes than in-office products, but they needed 14 to 280 times longer treatment durations.

Exercise induced hypoalgesia profile in rats is associated with IL-10 and IL-1 ß levels and pain severity following nerve injury.

BACKGROUND: Pain may undergo modulation in the central nervous system prior to reaching the primary somatosensory cortex and being perceived as pain. Faulty pain modulation mechanisms have been linked to various chronic pain conditions. Cytokines such as IL-10 and IL-1beta, are known to be involved in initiation and maintenance of neuropathic pain. In this study, we investigated the association between pain modulation profile, pain intensity and cytokines (IL-10 and IL-1beta) levels in a rat model of neuropathic pain. METHODS: Exercise-Induced Hypoalgesia (EIH) was assessed by evaluating the percentage of responses to a train of 60g mechanical stimuli before and after 180 seconds of exercise on a rotating rod. The differences in the response rates before and after the exercise were used to divide the rats into low and high EIH responders. Rats from low and high EIH groups underwent constriction injury of the left sciatic nerve. Pain behavior (allodynia and hyperalgesia) were assessed by measuring responses to mechanical and thermal stimuli applied to the plantar surface of the foot. Serum, sciatic nerve and the related Dorsal Root Ganglia (DRG) levels of IL-10 and IL-1beta were determined by ELISA. The DRG mRNA levels of IL-10 and IL-1beta measured with PCR. A comparison between the low and high EIH rats of all measured parameters was made. RESULTS: The low EIH rats developed significantly more severe allodynia and hyperalgesia in the affected paw and allodynia in the contralateral paw compared to the high EIH rats, 7 days following the injury. The low EIH rats had higher IL-1beta protein levels in serum prior to and following injury, higher affected and contralateral sciatic nerve IL-1beta levels following injury and higher IL-1beta levels in the contralateral DRG (protein and mRNA) following injury when compared to high EIH rats. The high EIH rats had higher affected sciatic nerve IL-10 levels following nerve injury and higher IL-10 levels of both protein and mRNA in the affected and contralateral DRG at baseline and following injury. CONCLUSION: EIH profile was found to be predictive of pain behavior following nerve injury, low EIH rats developed more severe allodynia and hyperalgesia. IL-1beta may be associated with painful neuropathy developed in rats with low EIH while the anti-inflammatory cytokine IL-10 may have a protective role, inhibiting the development of painful.

Clinical characteristics and risk factors of major oral ulcers in the mandibular retromolar region in children.

OBJECTIVES: To describe the characteristics of major aphthous ulcers (MjOU) in children and analyze its potential risk factors. MATERIALS AND METHODS: Data were collected from the National Clinical Research Center for Oral Diseases of China between 2012 and 2017. Children younger than 15 years old, who had a giant mucosa ulcer (≥ 1 cm in diameter) and met the diagnostic criteria for MjOU were included in this study. Differences were compared between two subgroups of patients based on the location of the ulcerous lesions. A measurement of ratio (TBR) between the length of the mandibular second molar tooth germ and the height of the mandible was performed in children with MjOU lesions located in the mandibular retromolar pad region (MjOU-P) and their age- and sex-matched controls. RESULTS: A total of 1067 children were diagnosed with oral ulcers during the study period, of which 125 (11.7%, 95% CI: 9.8%-13.7%) met the diagnostic criteria for MjOU. More than half (n = 64, 51.2%) of the MjOU cases were MjOU-P, which had a male predilection (n = 52, 81.3%) with a significant majority at 7 to 9 years of age (n = 43, 67.2%). In comparison to the MjOU located in other regions, MjOU-P lasted longer in duration and had more comorbidities. Logistic regression analysis showed that MjOU-P was statistically significantly associated with TBR controlling age and gender. CONCLUSIONS: MjOU-P is a predominant form of MjOU in children and is a distinct subgroup of major ulcers that is likely associated with the development of the mandibular second molars. CLINICAL RELEVANCE: This study is the first to describe the demographic and clinical features of MjOU in children, which may facilitate the identification and treatment of these patients.

Effects of whitening toothpaste and bleaching treatment on resin composite discoloration caused by cigarette smoke and electronic vapor aerosol.

PURPOSE: To compare the effects of whitening toothpaste and bleaching with 6% hydrogen peroxide (H2O2) on discoloration of dental resin composite caused by cigarette smoke (CS) and electronic vapor product (EVP) aerosol. METHODS: 40 resin composite discs were divided into three groups: 15 each for CS and EVP aerosol exposure and 10 for air exposure (control). Exposures were performed for 15 days, with daily brushing with regular toothpaste. Two whitening sessions, including 21 days of brushing with whitening toothpaste and 3 days of treatments with take-home bleaching (6% H2O2), were performed after the exposure. Color and gloss were assessed before exposure, at every 5 days of exposure, and after each whitening session. RESULTS: After 15 days of exposure, marked discoloration of resin composite was observed in the CS group (ΔE = 23.66 ± 2.31), minimal color change in the EVP group ((ΔE = 2.77 ± 0.75), and no color change in the control group. Resin composites exposed to CS did not recover their original color after treatment with whitening toothpaste ((ΔE = 20.17 ± 2.68) or take-home bleaching ((ΔE = 19.32 ± 2.53), but those exposed to EVP aerosol reverted to baseline after treatment with whitening toothpaste ((ΔE = 0.98 ± 0.37), and no further change in color was observed following take-home bleaching. The gloss of resin composites exposed to CS, EVP aerosol, and air decreased equally with exposure time. Brushing with whitening toothpaste recovered the gloss similarly in all groups, but no further change was observed following take-home bleaching. CLINICAL SIGNIFICANCE: Aerosol from electronic vapor products induced minimal discoloration of resin composites that can be completely reverted by brushing with whitening toothpaste alone. Bleaching with 6% H2O2 did not revert discoloration caused by cigarette smoke. Whitening toothpaste could help revert the decreased gloss of resin composites.

Effects of desensitizing dentifrices on dentin tubule occlusion and resistance to erosive challenges.

BACKGROUND: Many studies have demonstrated efficacy of casein phosphopeptide (CPP) containing products for dentin tubule occlusion for treatment of dentin sensitivity, but their effectiveness under dynamic erosive challenges remains to be elucidated. The purpose of the present study was to investigate the effectiveness of a desensitizing dentifrice containing CPP in occluding dentin tubules and resisting erosive challenges in comparison to that containing polyvinyl methyl ether/maleic acid (PVM/MA) copolymers. METHODS: A total of 33 dentin discs were prepared from coronal sections of human third molars and divided into 3 groups: a toothpaste containing CPP; a toothpaste containing PVM/MA and submicron silica; and a regular toothpaste (Controls). A soft-bristle toothbrush was used to brush the dentin discs with the dentifrices for 45 strokes in 30 s at a force of approximately 200 g. The brushing cycle was repeated after immersion of the dentin discs in artificial saliva overnight. The dentin discs were then challenged in orange juice for 10 min in an incubator rocking at 120 rpm. Three fields were randomly selected on each dentin disk surface to assess dentin tubule occlusions after each brushing cycle and after orange juice challenge with a 3D laser scanning microscope. Specimen cross sections were examined with a scanning electron microscope equipped with energy dispersive spectroscopy (SEM/EDS). RESULTS: After the first and second cycles of brushing, dentin tubules were occluded on average by 56.3% and 85.7% in CPP group, 66.2% and 88.1% in PVM/MA group, and 0.0 and 13.0% in the controls, respectively. There were no statistically significant differences in dentin tubule occlusions between the CPP and PVM/MA groups after two cycles of brushing (p>0.05). After dynamic erosive challenges with orange juice, 20.3% of the dentin tubules in the CPP group, 79.1% in the PVM/MA group and none in the control remained occluded (P<0.05). SEM/EDS imaging showed that dentin tubules were blocked with plugs containing dentifrice substances in CPP and PVM/MA groups after treatments, but none in the controls. CONCLUSIONS: Desensitizing dentifrices containing CPP or PVM/MA could effectively occlude dentin tubules after two cycles of brushing. PVM/MA in combination with submicron silicon dioxide exhibited stronger resistance to dynamic erosive challenges by acidic beverages. Inorganic fillers that can enter dentin tubules and resist erosive challenges may be key for desensitizing dentifrices.

Nitric oxide alleviates salt stress in seed germination and early seedling growth of pakchoi (Brassica chinensis L.) by enhancing physiological and biochemical parameters.

The germination and seedling vigor of crops is negatively affected by soil salinity. Nitric oxide (NO) has emerged as a key molecule involved in many physiological events in plants. The objective of present study was to evaluate the impact of exogenous sodium nitroprusside (SNP, a NO donor) at different concentrations on the seed germination and early seedling growth characteristics of pakchoi (Brassica chinensis L.) under NaCl stress. 100 mM NaCl stress markedly inhibited the seed germination potential, germination index, vitality index and growth of radicles and plumules. SNP pretreatment attenuated the salt stress effects in a dose-dependent manner, as indicated by enhancing the characteristics of seed germination and early seedling growth parameters, and the mitigating effect was most pronounced at 10 µM SNP. Efficient antioxidant systems were activated by SNP pre-treatment, and which effectively increased the activities of superoxide dismutase (SOD), catalase (CAT) and ascorbate peroxidase (APX), and reduced contents of malondialdehyde (MDA) and hydrogen peroxide (H2O2) and the production rate of superoxide anion radical (O2·-) in radicles and plumules, thereby preventing oxidative damage from NaCl stress. SNP pre-treatment also increased the contents of proline and soluble sugar in radicles and plumules under NaCl stress. In addition, SNP pre-treatment significantly increased the K+ contents and decreased Na+ contents in radicles and plumules, resulting in the increased level of K+/Na+ ratio. Our results demonstrated that SNP application on pakchoi seeds may be a good option to improve seed germination and seedling growth under NaCl stress by modulating the physiological responses resulting in better seed germination and seedling growth.

Pathogenesis, diagnosis and management of dentin hypersensitivity: an evidence-based overview for dental practitioners.

Though dentin hypersensitivity (DHS) is one of the most common complaints from patients in dental clinics, there are no universally accepted guidelines for differential diagnosis as well as selection of reliable treatment modalities for this condition. The neurosensory mechanisms underlying DHS remain unclear, but fluid movements within exposed dentinal tubules, i.e., the hydrodynamic theory, has been a widely accepted explanation for DHS pain. As several dental conditions have symptoms that mimic DHS at different stages of their progression, diagnosis and treatment of DHS are often confusing, especially for inexperienced dental practitioners. In this paper we provide an up-to-date review on risk factors that play a role in the development and chronicity of DHS and summarize the current principles and strategies for differential diagnosis and management of DHS in dental practices. We will outline the etiology, predisposing factors and the underlying putative mechanisms of DHS, and provide principles and indications for its diagnosis and management. Though desensitization remains to be the first choice for DHS for many dental practitioners and most of desensitizing agents reduce the symptoms of DHS by occluding patent dentinal tubules, the long-term outcome of such treatment is uncertain. With improved understanding of the underlying nociceptive mechanisms of DHS, it is expected that promising novel therapies will emerge and provide more effective relief for patients with DHS.

Phytotoxicity Assessment of Copper Oxide Nanoparticles on the Germination, Early Seedling Growth, and Physiological Responses in Oryza sativa L.

The increasing utilization of copper oxide nanoparticles (CuO NPs) and their release into the environment has made it imperative to elucidate their impact on the ecological system including plants. However, their potential toxic impact and mechanisms on plant growth are still unclear. The aim of this study was to investigate the effects of CuO NPs and released Cu ions on seed germination and early seedling growth, as well as physiological and biochemical parameters of Oryza sativa. The results showed that CuO NPs at high concentration significantly inhibited seed germination and early seedling growth. The toxicity of CuO NPs originated from the particulate NPs rather than the released Cu2+. The phytotoxicity of CuO NPs to rice seed germination and seedling growth probably induced by high Cu accumulation along with the lignification and oxidative damage. The work presented here will increase our knowledge of phytotoxicity of CuO NPs.

TBL10 is required for O-acetylation of pectic rhamnogalacturonan-I in Arabidopsis thaliana.

O-Acetylated pectins are abundant in the primary cell wall of plants and growing evidence suggests they have important roles in plant cell growth and interaction with the environment. Despite their importance, genes required for O-acetylation of pectins are still largely unknown. In this study, we showed that TRICHOME BIREFRINGENCE LIKE 10 (AT3G06080) is involved in O-acetylation of pectins in Arabidopsis (Arabidopsis thaliana). The activity of the TBL10 promoter was strong in tissues where pectins are highly abundant (e.g. leaves). Two homozygous knock-out mutants of Arabidopsis, tbl10-1 and tbl10-2, were isolated and shown to exhibit reduced levels of wall-bound acetyl esters, equivalent of ~50% of the wild-type level in pectin-enriched fractions derived from leaves. Further fractionation revealed that the degree of acetylation of the pectin rhamnogalacturonan-I (RG-I) was reduced in the tbl10 mutant compared to the wild type, whereas the pectin homogalacturonan (HG) was unaffected. The degrees of acetylation in hemicelluloses (i.e. xyloglucan, xylan and mannan) were indistinguishable between the tbl10 mutants and the wild type. The mutant plants contained normal trichomes in leaves and exhibited a similar level of susceptibility to the phytopathogenic microorganisms Pseudomonas syringae pv. tomato DC3000 and Botrytis cinerea; while they displayed enhanced tolerance to drought. These results indicate that TBL10 is required for O-acetylation of RG-I, possibly as an acetyltransferase, and suggest that O-acetylated RG-I plays a role in abiotic stress responses in Arabidopsis.

Prenatal Oral Health Care and Early Childhood Caries Prevention: A Systematic Review and Meta-Analysis.

Despite the advancement of early childhood caries (ECC) prediction and treatment, ECC remains a significant public health burden in need of more effective preventive strategies. Pregnancy is an ideal period to promote ECC prevention given the profound influence of maternal oral health and behaviors on children's oral health. However, studies have shown debatable results with respect to the effectiveness of ECC prevention by means of prenatal intervention. Therefore, this study systematically reviewed the scientific evidence relating to the association between prenatal oral health care, ECC incidence, and Streptococcus mutans carriage in children. Five studies (3 randomized control trials, 1 prospective cohort study, and 1 nested case-control study) were included for qualitative assessment. Tested prenatal oral health care included providing fluoride supplements, oral examinations/cleanings, oral health education, dental treatment referrals, and xylitol gum chewing. Four studies that assessed ECC incidence reduction were included in meta-analysis using an unconditional generalized linear mixed effects model with random study effects and age as a covariate. The estimated odds ratio and 95% confidence intervals suggested a protective effect of prenatal oral health care against ECC onset before 4 years of age: 0.12 (0.02, 0.77) at 1 year of age, 0.18 (0.05, 0.63) at 2 years of age, 0.25 (0.09, 0.64) at 3 years of age, and 0.35 (0.12, 1.00) at 4 years of age. Children's S. mutans carriage was also significantly reduced in the intervention group. Future studies should consider testing strategies that restore an expectant mother's oral health to a disease-free state during pregnancy.

Effectiveness of resin-based materials against erosive and abrasive enamel wear.

OBJECTIVE: The objective of this study was to test the effectiveness of resin-based materials against erosive enamel wear under erosive and abrasive challenges by orange juice and tooth brushing. METHODS: Fifty enamel specimens from third molars were assigned to five groups: ICON resin infiltration with no etching (ICON-NE), ICON resin infiltration with 15 % HCl etching (ICON-AE), Seal & Protect sealant (S&P), Tetric EvoFlow (TEF), and control. Erosive lesions were first created on enamel, then treated with resin-based materials. Erosive and abrasive challenges by orange juice and tooth brushing were repeated after treatments. Erosive wear of the treated areas was measured with 3D scanning microscopy, and data were analyzed using ANOVA and paired t tests. RESULTS: Treatments with ICON, S&P, and TEF created a protective material coating of 4.5 ± 1.9 µm, 44.3 ± 8.1 µm, and 84.6 ± 15.7 µm in thickness on the lesion surfaces, respectively. After 15 cycles of erosive and abrasive challenges, enamel or material losses were 21.9 ± 2.3 µm for control, 24.5 ± 4.0 µm for ICON-NE, 24.6 ± 7.4 µm for ICON-AE, 11.2 ± 4.1 µm for S&P, and 3.9 ± 1.9 µm for TEF, respectively. The protective coatings were completely lost in the ICON infiltration groups but remained intact in both the S&P and TEF groups after erosive and abrasive challenges. CONCLUSION: In contrast to a resin sealant and a flowable composite, ICON infiltration resin was not effective in protecting enamel surfaces from erosive and abrasive wear. CLINICAL RELEVANCE: Sealant and flowable composite resin may create protective coatings on eroded enamel surfaces and prevent further tissue loss.

Effects of cigarette smoking on color stability of dental resin composites.

PURPOSE: To study the effects of cigarette smoke (CS) on the discoloration of dental resin composite compared with the aerosol from a heat-not-burn tobacco product, the Tobacco Heating System 2.2 (THS2.2). METHODS: A total of 60 discs were prepared from three commercial resin composites: Durafill VS (DVS), Filtek Supreme Ultra (FSU) and Tetric EvoCeram BulkFill (TEC). Twenty discs of each composite were divided into two groups and exposed to CS from 20 reference cigarettes (3R4F) or aerosol from 20 THS2.2 tobacco sticks per day for 3 weeks. Color, gloss and surface roughness of the composite discs were measured at baseline and after exposure and brushing with toothpaste at 1, 2 and 3 weeks. RESULTS: Color differences from the baseline (ΔE) were on average 27.1 (±3.6) in 3R4F and 3.9 (±1.5) in the THS2.2 group after 3 weeks of exposure (P< 0.0001). TEC (30.4±1.4 and FSU (28.0 ±2.5) exhibited more discoloration than DVS (23.0±1.2) in the 3R4F group (P< 0.0001). FSU (2.6 ±0.5) showed significantly less discoloration than TEC (5.3±1.5) in the THS2.2 group (P< 0.0001). Surface roughness of resin composites was not affected by either CS or THS2.2 aerosol, while surface gloss increased in the composite discs with more severe discoloration. CLINICAL SIGNIFICANCE: Cigarette smoke caused significant discoloration of dental composite resins. Reducing or eliminating the deposits derived from combustion of tobacco has the potential to minimize the impact of smoking on the color of composite resin restorations.

Success rate of short dental implants supporting single crowns and fixed bridges.

OBJECTIVE: Bone grafts (sinus lift and/or ridge augmentation) may become an obstacle for some patients who desire implant treatment. The objective of this study was to evaluate the success of six- and eight-millimeters rough surface design short dental implants, for up to 2 years in function, when compared to conventional length (11 mm) implants. MATERIALS AND METHODS: A total of 25.6-, 20.8- and 35.11-mm length implants were placed and restored in 30 subjects (11 males, 19 females) between the age of 22 and 80, following a standard protocol. Implant mobility, crestal bone loss as well as periodontal parameters were evaluated immediately after restoration placement, at 6, 12 and 24 months. RESULTS: There was one failure of one 6-mm implant during the healing phase and one restorative failure. The median crestal bone loss at 24 months was 0.45 mm for the 6-mm implants, 0.55 mm for the 8 mm implants and 0.65 mm for the 11-mm implants. The success rate for 6-mm implants was 97% and for 8-mm and 11-mm implants 100%. CONCLUSIONS: Based on this preliminary data, we conclude that rough surface design short dental implants (6 and 8 mm in length) have similar success rate when compared to 11-mm implants. Long-term data with larger number of implants and subjects are needed to confirm these results.

Reciprocal interaction between dental alloy biocorrosion and Streptococcus mutans virulent gene expression.

Corrosion of dental alloys is a major concern in dental restorations. Streptococcus mutans reduces the pH in oral cavity and induces demineralization of the enamel as well as corrosion of restorative dental materials. The rough surfaces of dental alloys induced by corrosion enhance the subsequent accumulation of plaque. In this study, the corrosion process of nickel-chromium (Ni-Cr) and cobalt-chromium (Co-Cr) alloys in a nutrient-rich medium containing S. mutans was studied using inductively coupled plasma atomic emission spectrometry (ICP-AES), X-ray photoelectron spectroscopy (XPS) and electrochemical corrosion test. Our results showed that the release of Ni and Co ions increased, particularly after incubation for 3 days. The electrochemical corrosion results showed a significant decrease in the corrosion resistance (Rp) value after the alloys were immersed in the media containing S. mutans for 3 days. Correspondingly, XPS revealed a reduction in the relative dominance of Ni, Co, and Cr in the surface oxides after the alloys were immersed in the S. mutans culture. After removal of the biofilm, the pre-corroded alloys were re-incubated in S. mutans medium, and the expressions of genes associated with the adhesion and acidogenesis of S. mutans, including gtfBCD, gbpB, fif and ldh, were evaluated by detecting the mRNA levels using real-time reverse transcription polymerase chain reaction (RT-PCR). We found that the gtfBCD, gbpB, ftf and Idh expression of S. mutans were noticeably increased after incubation with pre-corroded alloys for 24 h. This study demonstrated that S. mutans enhanced the corrosion behavior of the dental alloys, on the other hand, the presence of corroded alloy surfaces up-regulated the virulent gene expression in S. mutans. Compared with smooth surfaces, the rough corroded surfaces of dental alloys accelerated the bacteria-adhesion and corrosion process by changing the virulence gene expression of S. mutans.

Interferon-γ regulates the function of mesenchymal stem cells from oral lichen planus via indoleamine 2,3-dioxygenase activity.

BACKGROUND: Little is known about mesenchymal stem cells (MSCs) in normal or inflammatory oral mucosal tissues, such as in oral lichen planus (OLP). Our objectives were to identify, isolate, and characterize MSCs from normal human oral mucosa and OLP lesions, and to evaluate indoleamine 2,3 dioxygenase (IDO) activity in mediating immunomodulation of MSCs from these tissues. METHODS: Expressions of MSCs-related markers were examined in isolated cells by flow cytometry. Self-renewal and multilineage differentiations were studied to characterize these MSCs. Interferon-γ (IFN-γ), IDO, and STRO-1 were assessed by immunofluorescence. MSCs from oral mucosa and OLP or IFN-γ-pretreated MSCs were co-cultured with allogeneic mixed lymphocyte reaction assays (MLR). Proliferation and apoptosis of MLR or MSCs were detected by CCK8 and the annexin V-FITC apoptosis detection kit, respectively. IDO expression and activity were measured by real-time PCR, Western blotting, and high-performance liquid chromatography. RESULTS: Isolated cells from oral mucosa and OLP expressed MSC-related markers STRO-1, CD105, and CD90 but were absent for hematopoietic stem cell markers CD34. Besides, they all showed self-renewal and multilineage differentiation capacities. MSCs in OLP presented STRO-1/IDO+ phenotype by immunofluorescence. MSCs and IFN-γ-pretreated MSCs could inhibit lymphocyte proliferation via IDO activity, but not via cell apoptosis. Long-term IFN-γ could also inhibit MSC proliferation via IDO activity. CONCLUSIONS: Mesenchymal stem cells can be isolated from human oral mucosa and OLP tissues. Besides self-renewal and multilineage differentiation properties, these cells may participate in immunomodulation mediated by IFN-γ via IDO activity in human OLP.

Porous collagen-hydroxyapatite scaffolds with mesenchymal stem cells for bone regeneration.

Current bone grafting materials have significant limitations for repairing maxillofacial and dentoalveolar bone deficiencies. An ideal bone tissue-engineering construct is still lacking. The purpose of the present study was first to synthesize and develop a collagen-hydroxyapatite (Col-HA) composite through controlled in situ mineralization on type I collagen fibrils with nanometer-sized apatite crystals, and then evaluate their biologic properties by culturing with mouse and human mesenchymal stem cells (MSCs). We synthesized Col-HA scaffolds with different Col:HA ratios. Mouse C3H10T1/2 MSCs and human periodontal ligament stem cells (hPDSCs) were cultured with scaffolds for cell proliferation and biocompatibility assays. We found that the porous Col-HA composites have good biocompatibility and biomimetic properties. The Col-HA composites with ratios 80:20 and 50:50 composites supported the attachments and proliferations of mouse MSCs and hPDSCs. These findings indicate that Col-HA composite complexes have strong potentials for bone tissue regeneration.

Protective roles of nitric oxide on seed germination and seedling growth of rice (Oryza sativa L.) under cadmium stress.

Nitric oxide (NO) is a bioactive molecule in plants which mediates a variety of physiological processes and responses to biotic and abiotic stresses including heavy metals. In the present study, the effects of exogenous NO donor sodium nitroprusside (SNP) on rice seed germination and seedlings growth were investigated under Cd stress and a possible mechanism was postulated. The results indicated that 100µM Cd significantly decreased rice seed germination index, vigor index, root and shoot lengths as well as fresh weight compared to control. Exogenous SNP dose-dependently attenuated the inhibition of rice seed germination and thereafter seedling growth caused by Cd. The promoting effect was most pronounced at 30µM SNP. Cd exposure caused oxidative stress by elevating hydrogen peroxide (H2O2) and malondialdehyde (MDA) contents in root and shoot of rice seedlings. 30µM SNP counteracted partly Cd toxicity by reducing the H2O2 and MDA contents of Cd-exposed seedlings. Meanwhile, application of SNP markedly stimulated the activities of superoxide dismutases (SOD), ascorbate peroxidases (APX), guaiacol peroxidase (POD) and catalases (CAT) compared with Cd treatment alone, thereby indicating the enhancement of the antioxidative capacity in the root and shoot under Cd stress. In addition, addition of 30µM SNP increased accumulation of proline in both root and shoot. The Cd accumulation in seedlings was significant reduced by SNP, implicating that the protective role of SNP was responsible for preventing Cd accumulation. However, the effects of SNP were reverted by addition of cPTIO, a NO scavenger, suggesting the protective roles of SNP might be related to the induction of NO. Furthermore, K3Fe(CN)6 and [Formula: see text] / [Formula: see text] had no similar roles as SNP. Based on these results, it can be concluded that SNP exerted an advantageous effect on alleviating the inhibitory effect of Cd on rice seed germination and seedling growth, which might interact with NO.

[Effects of small interfering RNA silencing MACC-1 expression on cell proliferation, cell cycle and invasion ability of cervical cancer SiHa cells].

OBJECTIVE: To investigate the expression of metastasis-associated in colon cancer-1 (MACC-1) mediated by siRNA, and to study the effects of its downregulation on cell proliferation, cell cycle and invasion ability of cervical cancer SiHa cells. METHODS: MACC-1 siRNA and control siRNA were transfected into cervical cancer SiHa cells, and the expression of MACC-1 protein after transfection with MACC-1 siRNA was detected by Western blotting. The changes of cell proliferation, cell cycle and invasion ability of the SiHa cells were determined by CCK-8 kit, flow cytometry and Boyden chamber assay. The expressions of cell cycle- and invasion-related proteins were analyzed by Western blotting. RESULTS: Compared with the untreated group (0.317 ± 0.023) and control siRNA group (0.309 ± 0.021), the expression of MACC-1 protein was downregulated in the MACC1 siRNA group (0.041 ± 0.006) (P < 0.05), and its downregulation significantly suppressed the cell proliferation, altered the cell cycle distribution and reduced the cell invasion ability of the SiHa cells (P < 0.05). Compared with the untreated group (0.217 ± 0.025 and 0.215 ± 0.024) and the control siRNA group (0.222 ± 0.023 and 0.207 ± 0.027), the expression of cyclin D1 and Cdk2 proteins were significantly decreased in the MACC1 siRNA group (0.076 ± 0.010 and 0.039 ± 0.007) (P < 0.05). Compared with the untreated group (0.099 ± 0.007) and control siRNA group (0.105 ± 0.012), the expression of p21 protein was significantly increased in the MACC1 siRNA group (0.676 ± 0.044) (P < 0.05). The downregulation of MACC-1 expression also evoked a decrease of expressions of MMP-2 and MMP-9 proteins and an increase of E-cadherin protein expression (P < 0.05). CONCLUSIONS: MACC-1 downregulation-mediated inhibition of proliferation and decreased invasion ability of tumor cells may be closely associated with the alterations of expressions of cell cycle- and invasion-related proteins.