Nicotine inhibits osteogenic differentiation of human periodontal ligament cells under cyclic tensile stress through canonical Wnt pathway and α7 nicotinic acetylcholine receptor

BACKGROUND AND OBJECTIVES

Nicotine, the main psychoactive component of tobacco, affects cell metabolism, proliferation, adhesion and, importantly, the osteogenic differentiation of fibroblasts. Approximately 15% of all orthodontic patients are adults among who one-fifth are smokers. Hence, it is necessary to have insight into the effects of nicotine on the osteogenic differentiation of hPDLCs during orthodontic tooth movement. This study aimed to investigate the effects and mechanisms of nicotine on the osteogenic differentiation of human periodontal ligament cells (hPDLCs) under the application of cyclic tensile stress.

MATERIAL AND METHODS

hPDLCs were obtained from donor third molars. The hPDLCs were treated with nicotine and/or cyclic tensile stress that was applied with a cell stress plus unit. The effect of nicotine on cell viability was analyzed using the MTT assay. The osteogenic differentiation of hPDLCs was detected by alkaline phosphatase staining, Alizarin Red S staining, quantitative real-time polymerase chain reaction and western blotting.

RESULTS

In combination with cyclic tensile stress, nicotine prevented the tensile stress-induced increase in alkaline phosphatase activity, formation of mineralization nodules and the upregulation of mRNA and protein expression of Runt-related transcription factor 2, transcription factor Sp7 and collagen type I; however, canonical Wnt pathway was activated. Furthermore, the addition of Dickkopf-related protein 1 and α-bungarotoxin counteracted the negative effect of nicotine and rescued the osteogenic differentiation of hPDLCs, respectively.

CONCLUSION

These results indicate that nicotine prevents the increased osteogenic potential of hPDLCs induced by cyclic tensile stress by binding to an α7 nicotinic acetylcholine receptor and activating the canonical Wnt pathway.

Analysis of the correlation between non-alcoholic fatty liver disease and bone metabolism indicators in healthy middle-aged men

OBJECTIVE

To investigate the relationship between bone metabolic indicators and non-alcoholic fatty liver disease (NAFLD) in healthy middle-aged men.

PATIENTS AND METHODS

The bone metabolic indicators of 232 healthy middle-age men with NAFLD (NAFLD group) and 308 healthy controls without fatty liver (Control group) were measured, including non-collagenous osteocalcin, the procollagen type 1 N-terminal propeptide (P1NP), beta-C-terminal telopeptide of type I collagen (β-CTX). The Student's t-test was used to analyze the differences in the bone metabolic indicators, age, clinical data, biochemical indicators, and the indicators of glucose and lipid metabolism between the two groups. The correlation of fatty liver-related indicators was detected using the logistic regression analysis.

RESULTS

The body mass index (BMI), diastolic blood pressure, and heart rate in NAFLD group were significantly higher than those in Control group. Among the indicators of glucose and lipid metabolism in NAFLD group, the levels of blood glucose [fasting plasma glucose, postprandial blood glucose and hemoglobin A1c (HbA1c)] were significantly higher than those in Control group. In addition, the insulin resistance and secretion indexes were also significantly higher than those in Control group. The levels of lipid metabolic indicators such as triglyceride were higher, but high-density lipoprotein cholesterol was lower than that in Control group. From logistic regression analysis, the BMI, Homeostasis model assessment (HOMA)-β, HOMA-IR, HbA1c and P1NP were positively associated with the occurrence of NAFLD.

CONCLUSIONS

The bone metabolic indicator P1NP might be a potential predicator for the diagnosis of NAFLD in clinical application.

Synthesis of 4-trifluoromethyl 2-pyrones and pyridones through the Brønsted base-catalyzed Pechmann-type reaction with cyclic 1,3-diones

An efficient Brønsted base-catalyzed Pechmann-type reaction of cyclic 1,3-diones with ethyl 4,4,4-trifluoroacetoacetate to afford 4-trifluoromethyl 2-pyrones and pyridones was developed.

[Primary investigation of immunoglobulin A synthesis and secretion in human mesangial cells]

OBJECTIVE

To investigate the expression of immunoglobulin A (IgA) in human mesangial cells (HMCs).

METHODS

The HMCs were cultured. The subcellular location of IgA was detected by immunofluorescence staining; the transcripts of Igα,Igκ and IgΛ constant region were detected by reverse transcription-polymerase chain reaction (RT-PCR) and further analyzed by DNA sequencing. The expressions of Igα and IgΛ were detected at transcription level by Western blot after the cytoplasmic protein extraction. The culture supernatant was collected to explore whether IgA could be secreted out of the cell and the protein was further analyzed by mass spectrometry after being purified by affinity chromato-graphy with jacalin-sepharose. The results of DNA sequencing and mass spectrometry were aligned with the mRNA and amino acid sequences in the National Center of Biotechnology Information (NCBI) database.

RESULTS

By immunofluorescence staining, we detected the presence of IgA heavy chain Igα, light chain, both Igκ and IgΛ in expressions of transcripts of Igα1, Igα2, Igκ and IgΛ in the HMCs and the alignment of the sequences of the RT-PCR products with those of the IgCα1, IgCα2, Igκ and IgΛ mRNA in the NCBI database exhibited that the similarities were 99%, 97%, 98% and 97%, respectively. Western blot showed Igα and IgΛ expressions in the cell lysate and secretion of Igα1 and Igα2 heavy chains in cell culture supernatant. To further explore the protein that secreted into the supernatant, after supernatant affinity chromatography with jacalin-sepharose, the proteins were separated by sodium dodecyl sulfonate-polyacrylamide gel electrophoresis (SDS-PAGE) and the band approximating to 65 000 was cut and sent to mass spectrometry. The results were aligned with the amino acid sequences of Igα1 and Igα2 constant region in NCBI database, showing that amino acids between No.52 and No.104, amino acids between No.154 and No.221, amino acids between No.276 and No.327 from IgCα1 and amino acids between No.52 and No.113, amino acids between No.151 and No.204, amino acids between No.251 and No.314 from IgCα2 were the same with those derived from B cells.

CONCLUSION

Our fin-dings suggested that HMCs could synthesize and secret IgA.

Effects of Fe plaque and organic acids on metal uptake by wetland plants under drained and waterlogged conditions

This study aims to assess the role of Fe plaque in metal uptake and translocation by different wetland plants and examine the effects of organic acids on metal detoxification in wetland plants. It was found that although exposed to a similar level of metals in rhizosphere soil solution, metal uptake by shoots of Cypercus flabelliformis and Panicum paludosum was greatly reduced, consequently leading to a better growth under flooded than under drained conditions. This may be related to the enhanced Fe plaque in the former, but due to the decreased root permeability in the latter under anoxic conditions. The Fe plaque on root surface has potential to sequester metals and then reduce metal concentrations and translocation in shoot tissues. However, whether the Fe plaque acts as a barrier to metal uptake and translocation may also be dependent on the root anatomy. Although metal tolerance in wetland plants mainly depends upon their metal exclusion ability, the higher-than-toxic-level of metal concentrations in some species indicates that internal metal detoxification might also exist. It was suggested that malic or citric acid in shoots of P. paludosum and C. flabelliformis may account for their internal detoxification for Zn.

Plasma vascular endothelial growth factor B levels are increased in patients with newly diagnosed type 2 diabetes mellitus and associated with the first phase of glucose-stimulated insulin secretion function of β-cell

PURPOSE

To detect plasma vascular endothelial growth factor B (VEGF-B) in individuals with different glucose tolerance and investigate the relationship between plasma VEGF-B levels and the first phase of glucose-stimulated insulin secretion.

METHODS

A cross-sectional study was conducted involving 45 patients with newly diagnosed type 2 diabetes mellitus (T2DM), 37 patients with impaired glucose regulation (IGR), and 39 Normal glucose tolerance (NGT) subjects, all of whom underwent intravenous glucose tolerance test. Plasma VEGF-B levels were assayed by ELISA. The first phase of insulin secretion was evaluated by acute insulin response (AIR), the area under the curve of the first-phase (0-10 min) insulin secretion (AUC) and glucose disposition index (GDI).

RESULTS

The T2DM and IGR groups had higher plasma VEGF-B levels than the NGT group (P < 0.01). Plasma VEGF-B levels were negatively correlated with AIR, AUC, GDI, HOMA-β (P < 0.01), and positively correlated with plasma glucose, HbA1c, triglyceride, free fatty acid (FFA), fasting insulin, and HOMA-IR (P < 0.01). Logistic regression analysis revealed that higher VEGF-B levels [145.59-180.07 pg/ml, OR 3.55 (95% CI 1.05-12.02) and >180.07 pg/ml, OR 3.64 (95% CI 1.16-11.42)] were related to a greater probability of β-cell hypofunction, compared with low VEGF-B levels (<145.59 pg/ml). After adjusting for triglyceride or FFA, the association between VEGF-B levels and β-cell hypofunction disappeared (P > 0.05).

CONCLUSIONS

Our study provides evidence that plasma VEGF-B levels were higher in patients with newly diagnosed T2DM, and were strongly associated with glucose and lipid metabolism and the first-phase insulin secretion function of β-cells. VEGF-B may be involved in the mechanism of β-cell dysfunction in T2DM.

Polyketides with different post-modifications from desert endophytic fungus Paraphoma sp

Three new polyketides 4,6,8-trihydroxy-5-methyl-3,4-dihydronaphthalen-1(2H)-one (1), 5,7-dihydroxy-3-(1-hydroxyethyl)-3,4-dimethylisobenzofuran-1(3H)-one (2) and 1-(4-hydroxy-6-methoxy-1,7-dimethyl-3-oxo-1,3-dihydroisobenzofuran-1-yl) ethyl acetate (3) together with seven known analogues (4-10) were isolated from desert endophytic fungus Paraphoma sp. The structures of these compounds were elucidated by analysis of NMR data. The absolute configuration of (1-3) was established on the basis of CD experiments. The possible biosynthetic pathway of compounds (1-10) was suggested, which implied that these secondary metabolites might be originated from polyketide biosynthesis with different post-modification reactions. Compounds 2, and 5-8 were evaluated for bioactivities against plant pathogen A. solani, whereas none of them displayed any biological effects. In addition, compounds 1, 2 and 5-10 were also tested for cytotoxic activities against three human cancer cell lines (HepG2 cells, MCF-7 cells and Hela cells) without biological effects.

Acceleration of sub-relativistic electrons with an evanescent optical wave at a planar interface

We report on a theoretical and experimental study of the energy transfer between an optical evanescent wave, propagating in vacuum along the planar boundary of a dielectric material, and a beam of sub-relativistic electrons. The evanescent wave is excited via total internal reflection in the dielectric by an infrared (λ = 2 μm) femtosecond laser pulse. By matching the electron propagation velocity to the phase velocity of the evanescent wave, energy modulation of the electron beam is achieved. A maximum energy gain of 800 eV is observed, corresponding to the absorption of more than 1000 photons by one electron. The maximum observed acceleration gradient is 19 ± 2 MeV/m. The striking advantage of this scheme is that a structuring of the acceleration element's surface is not required, enabling the use of materials with high laser damage thresholds that are difficult to nano-structure, such as SiC, Al₂O₃ or CaF₂.

Genetic analysis of PITX3 variants in patients with essential tremor

BACKGROUND

A clinical overlap between essential tremor (ET) and Parkinson's disease (PD) has prompted investigation whether these disorders share common genetic factors. The paired-like homeodomain transcription factor 3 gene (PITX3) has been shown to play an important role for the differentiation and survival of midbrain dopaminergic neurons in the substantia nigra pars compacta. The preferential degeneration of those dopaminergic neurons is the pathological hallmark in PD.

AIMS OF THE STUDY

The purpose of this study was to evaluate whether PITX3 variants are related to susceptibility of ET in Chinese Han population.

METHODS

Genetic analysis of two variants rs3758549 and rs4919621 of the PITX3 gene was conducted in 200 Chinese Han patients with ET and 426 controls.

RESULTS

We did not identify any statistically significant difference in either genotypic or allelic frequencies of variants between the ET patients and control cohort (all P > 0.05). Haplotype analysis of two variants in the PITX3 gene showed no potential association between the haplotypes and risk of ET (all P > 0.05).

CONCLUSIONS

Our data suggest that PITX3 variants rs3758549 and rs4919621 are not associated with ET in Chinese Han population.

Optical gating and streaking of free electrons with sub-optical cycle precision

The temporal resolution of ultrafast electron diffraction and microscopy experiments is currently limited by the available experimental techniques for the generation and characterization of electron bunches with single femtosecond or attosecond durations. Here, we present proof of principle experiments of an optical gating concept for free electrons via direct time-domain visualization of the sub-optical cycle energy and transverse momentum structure imprinted on the electron beam. We demonstrate a temporal resolution of 1.2±0.3 fs. The scheme is based on the synchronous interaction between electrons and the near-field mode of a dielectric nano-grating excited by a femtosecond laser pulse with an optical period duration of 6.5 fs. The sub-optical cycle resolution demonstrated here is promising for use in laser-driven streak cameras for attosecond temporal characterization of bunched particle beams as well as time-resolved experiments with free-electron beams.

[Selection of peer educators for sex education program-based on data from social network analysis among college freshmen students]

Objective: Through combining the results from social network analysis and willingness of the key actors, peer educators for sex education among freshmen to select peer educators for sex education. Methods: Self-developed questionnaires were used to collect information on related demographics, egocentric social networks and whole class-based unit-network. Descriptive analysis was applied. UCINET 6 was used to conduct social network analysis and to draw the whole networking graphs. Results: Classmates appeared as the most important behavior intimate social network (95.8% claimed they could potentially borrow money from them, and 96.6% often went out with them) and were the most important members who could share privacy information with (91.6%) and consulting for private health information on (89.1%), among freshmen students in college. Finally, 17 freshmen were selected to have become peer educators, with 10 of them as the committee members in the class. Conclusion: Classmates formed the most important social network among freshmen students in college. Social network analysis could be used to help identify the suitable peer educators.

Identification of a PRX variant in a Chinese family with congenital cataract by exome sequencing

BACKGROUND

Congenital cataract is a common cause of childhood vision impairment or blindness with genetic and clinical heterogeneity. The aim of this study was to identify the disease-associated gene in a Chinese family with congenital cataract.

METHODS

A four-generation Chinese family with three enrolled patients suffering from congenital cataract was studied. Detailed family history and clinical data of all the members were collected and recorded. Exome sequencing was applied in the proband to screen potential genetic variants, and then Sanger sequencing was used to verify the variant within the family.

RESULTS

A heterozygous variant, c.3673G > A (p.V1225M), in the periaxin gene (PRX) was identified in three patients and two asymptomatic individuals of the family. The variant was absent in the other three unaffected family members and in 3290 ethnically matched in-house controls from BGI-Shenzhen.

CONCLUSIONS

By utilizing both exome sequencing and Sanger sequencing, we identified a missense variant in the PRX gene that is possibly associated with disease in this family. Our finding may broaden the spectrum of genes associated with congenital cataract, and may provide insights into lens development, pathogenic mechanism, future clinical genetic diagnosis and therapy of congenital cataract.

Cell fate conversion-from the viewpoint of small molecules and lineage specifiers

Mammalian development was generally considered a naturally unidirectional and irreversible process. However, pioneering work of recent decades has highlighted the plasticity of mammalian cells and implied the possibilities of manipulating cell fate in vitro. Pluripotent stem cells, which hold great potential for regenerative medicine, have been shown to be reprogrammed from differentiated cells either by somatic cell nuclear transfer or by ectopic expression of pluripotency factors. Nevertheless, it remained unknown whether the reprogramming could be accomplished without pluripotency genes. Recent studies show that lineage specifiers play an important role in orchestrating the process of restoring pluripotency by replacing pluripotency-associated transcription factors. Moreover, a combination of small molecules enables the acquisition of pluripotency from somatic cells without any transgenes, offering a tractable platform to precisely dissect the induction and maintenance of cell identity. Here, we will discuss recent scientific advances regarding the cell fate conversion mediated by small molecules or lineage specifiers, especially in the chemically induced somatic cell reprogramming process, and will provide new insights into the intermediate plastic state and "seesaw model" established by chemical approaches during reprogramming.

Commensurability Oscillations of Composite Fermions Induced by the Periodic Potential of a Wigner Crystal

When the kinetic energy of a collection of interacting two-dimensional (2D) electrons is quenched at very high magnetic fields so that the Coulomb repulsion dominates, the electrons are expected to condense into an ordered array, forming a quantum Wigner crystal (WC). Although this exotic state has long been suspected in high-mobility 2D electron systems at very low Landau level fillings (ν≪1), its direct observation has been elusive. Here we present a new technique and experimental results directly probing the magnetic-field-induced WC. We measure the magnetoresistance of a bilayer electron system where one layer has a very low density and is in the WC regime (ν≪1), while the other ("probe") layer is near ν=1/2 and hosts a sea of composite fermions (CFs). The data exhibit commensurability oscillations in the magnetoresistance of the CF layer, induced by the periodic potential of WC electrons in the other layer, and provide a unique, direct glimpse at the symmetry of the WC, its lattice constant, and melting. They also demonstrate a striking example of how one can probe an exotic many-body state of 2D electrons using equally exotic quasiparticles of another many-body state.

Coherent population transfer between uncoupled or weakly coupled states in ladder-type superconducting qutrits

Stimulated Raman adiabatic passage offers significant advantages for coherent population transfer between uncoupled or weakly coupled states and has the potential of realizing efficient quantum gate, qubit entanglement and quantum information transfer. Here we report on the realization of the process in the superconducting Xmon and phase qutrits—two ladder-type three-level systems in which the ground state population is coherently transferred to the second excited state via the dark state subspace. We demonstrate that the population transfer efficiency is no less than 96% and 67% for the two devices, which agree well with the numerical simulation of the master equation. Population transfer via stimulated Raman adiabatic passage is significantly more robust against variations of the experimental parameters compared with that via the conventional resonant π pulse method. Our work opens up a new venue for exploring the process for quantum information processing using the superconducting artificial atoms.

Quantum state engineering necessitates transfer between quantum states. Here the authors demonstrate coherent population transfer between un- or weakly-coupled states of solid state systems, superconducting Xmon and phase qutrits, using stimulated Raman adiabatic passage and microwave driving.