Role of low-density lipoprotein in mediating the effect of air pollution on coronary heart disease: a two-step multivariate Mendelian randomization study

OBJECTIVE

Air pollution is affecting the health of millions of people all over the world. The causal correlations of PM2.5, PM10, and nitrogen dioxide (NOx), as the main fine particulate matter, and coronary heart disease (CHD) are yet to be explored. Low-density lipoprotein (LDL) has been a principal factor in the pathogenesis of CHD. It is an interesting issue to consider whether LDL mediates the effect of air pollutants in CHD pathogenesis.

MATERIALS AND METHODS

A genome-wide association study (GWAS) on the European population, followed up from 2010 to 2018, involving over 400,000 participants, was based on a land-use regression model. The annual mean concentrations of major air pollutant particles, PM2.5 (n=423,796), PM10 (n=423,796), and NOx (n=456,380), were recorded. The large GWAS database of CHD covered over ten million SNPs with independent single nucleotide polymorphisms (SNPs). LDL database collected major biochemical blood parameters from over 400,000 patients (n=440,546). Taken together, we conducted independent two-sample Mendelian randomization (MR) analyses for the causality between air pollutants (PM2.5, PM10, and NOx) and CHD. Multivariate MR analysis was conducted using causal relationships to determine the direct effects of exposure on outcome. The fixed-effect inverse variance weighted (IVW2) method was mainly employed to assess this relationship, with a confidence interval of 95% for the odds ratio (OR). Also, MR-Egger, weighted median, maximum likelihood ratio method, and random-effects inverse variance-weighted (IVW1) method were adopted as supplementary methods.

RESULTS

Two-sample MR results based on the IVW2 method suggested positive correlations between PM2.5 and CHD [OR 1.875 (1.279-2.748), p=0.001], PM10 and CHD [OR 2.586 (1.479-4.523), p=0.001], and NOx and CHD [OR 2.991 (2.021-4.427), p=4.37E-08]. The direct effect and mediating proportion were calculated using multivariable Mendelian randomization (MVMR). Lastly, the mediating proportions of LDL in the regulatory roles of PM2.5, PM10, and NOx in CHD were 2.82%, 4.73%, and 9.54%, respectively.

CONCLUSIONS

PM2.5, PM10, and NOx share direct causal associations with CHD, and LDL performs a mediating role in this pathogenic process. Early prevention against air pollution (such as increasing green areas and reducing large-scale industrial dust emissions) and early lipid-lowering treatment can effectively prevent the occurrence of CHD.

miR-200a attenuated oxidative stress, inflammation, and apoptosis in dextran sulfate sodium-induced colitis through activation of Nrf2

Introduction

Oxidative stress and inflammatory responses are critical factors in ulcerative colitis disease pathogenesis. Nuclear factor erythroid 2-related factor 2 (Nrf2) modulates oxidative stress and suppresses inflammatory responses, and the protective benefits of Nrf2 activation have been associated with the therapy of ulcerative colitis. MicroRNA-200a (miR-200a) could target Kelch-like ECH-associated protein 1 (Keap1) and activate the Nrf2-regulated antioxidant pathway. Nevertheless, whether miR-200a modulates the Keap1/Nrf2 pathway in dextran sulfate sodium (DSS)-induced colonic damage is unknown. Here, our research intends to examine the impact of miR-200a in the model of DSS-induced colitis.

Methods

Prior to DSS intervention, we overexpressed miR-200a in mice for four weeks using an adeno-associated viral (AAV) vector to address this problem. ELISA detected the concentration of inflammation-related cytokines. The genes involved in inflammatory reactions and oxidative stress were identified using quantitative reverse transcription-polymerase chain reaction (qRT-PCR), western blot, and immunofluorescence. Moreover, we applied siRNAs to weakened Nrf2 expression to confirm the hypothesis that miR-200a provided protection via Nrf2.

Results

The present study discovered miR-200a down-regulation, excessive inflammatory activation, enterocyte apoptosis, colonic dysfunction, and Keap1/Nrf2 antioxidant pathway inactivation in mouse colitis and NCM460 cells under DSS induction. However, our data demonstrated that miR-200a overexpression represses Keap1 and activates the Nrf2 antioxidant pathway, thereby alleviating these adverse alterations in animal and cellular models. Significantly, following Nrf2 deficiency, we failed to observe the protective benefits of miR-200a against colonic damage.

Discussion

Taken together, through activating the Keap1/Nrf2 signaling pathway, miR-200a protected against DSS-induced colonic damage. These studies offer an innovative therapeutic approach for ulcerative colitis.

The role of Nrf2 in the pathogenesis and treatment of ulcerative colitis

Ulcerative colitis (UC) is a chronic inflammatory bowel disease involving mainly the colorectal mucosa and submucosa, the incidence of which has been on the rise in recent years. Nuclear factor erythroid 2-related factor 2 (Nrf2), known for its key function as a transcription factor, is pivotal in inducing antioxidant stress and regulating inflammatory responses. Numerous investigations have demonstrated the involvement of the Nrf2 pathway in maintaining the development and normal function of the intestine, the development of UC, and UC-related intestinal fibrosis and carcinogenesis; meanwhile, therapeutic agents targeting the Nrf2 pathway have been widely investigated. This paper reviews the research progress of the Nrf2 signaling pathway in UC.

Maternal vitamin D deficiency aggravates the dysbiosis of gut microbiota by affecting intestinal barrier function and inflammation in obese male offspring mice

OBJECTIVES

The colonization of gut microbiota during early life may play a critical role in the progression of metabolic syndrome in adulthood. Targeting gut-based genes in the barrier function, inflammation, and lipid transportation are potential therapies for obesity. Therefore, this study focused on whether maternal deficient vitamin D (VD) intake could aggravate the dysbiosis of gut microbiota by affecting the expressions of these genes in the ileum and colon of obese male offspring mice.

METHODS

Four-week-old female C57 BL/6 J mice were fed normal (VD-C) or VD-deficient (VD-D) reproductive diets throughout pregnancy and lactation (n = 15/group). Weaning male pups (n = 10/group) were fed either a high-fat (HFD; VD-C-HFD, VD-D-HFD) or normal-fat diet (control) for 16 wk. All biologic samples were obtained after the mice were anesthetized by cervical dislocation. Subsequently, the compositions of the gut microbiota in cecal contents were analyzed using 16 S ribosomal RNA sequencing. Messenger RNA expression in the ileum and colon was determined using real-time reverse transcription-polymerase chain reaction. The distributions of ZO-1 and Claudin-1 were determined using immunohistochemistry testing.

RESULTS

Maternal deficient VD intake significantly aggravated the dysbiosis of gut microbiota persisting into adulthood from phylum to genus levels in the cecal contents among obese male offspring mice. This aggravation led to significantly depleted Bacteroidetes and Verrucomicrobia (Akkermansia, Alliprevotella, and Bacteroides), with higher relative abundance of Firmicutes (Lactobacillus, Lachnoclostridium, Romboutsia, and Ruminiclostridium_9) and Firmicutes/Bacteroidetes. The gene expressions of proinflammatory cytokines (Ccl2, Ccl4 and interleukin-1β) and lipid transportation molecules (Ffar3, Fabp4, and Fabp1) were higher, and the levels of intestinal barrier function (Occludin, ZO-1, and Claudin-1) were lower in the VD-D-HFD group than those in the VD-C-HFD group. Furthermore, there were significant correlations between the dysbiosis of intestinal microbials and expressions of genes related to barrier function, inflammation, and lipid transportation in the ileum and/or colon.

CONCLUSIONS

Maternal VD deficiency during pregnancy and lactation could aggravate the dysbiosis of gut microbiota to affect the progression of obesity among male offspring, which might be regulated by genes associated with barrier function, inflammation, and lipid transportation. So early life appropriate VD intake could play a significant role in preventing later obesity.

Inhibition of IRAK 1/4 alleviates colitis by inhibiting TLR4/ NF-κB pathway and protecting the intestinal barrier

Interleukin-1 receptor-associated kinase 1/4 (IRAK1/4) is the main kinase of the Toll-like receptor (TLR)-mediated pathway, considered a new target for treating inflammatory diseases. Studies showed a significant correlation between TLRs and inflammatory responses in ulcerative colitis (UC). Therefore, in this study, after inducing experimental colitis in mice with 3% dextran sulfate sodium (DSS), different concentrations of IRAK1/4 inhibitors were administered intraperitoneally. Then, the disease activity index was assessed, including the degree of pathological damage, by HE staining. Subsequently, while western blotting detected the TLR4/NF-κB pathway and intestinal barrier protein expression (Zonula-1, Occludin, Claudin-1, JAM-A), real-time polymerase chain reaction (RT-PCR) detected the mRNA expression levels of IRAK1/4 and mucin1/2. Furthermore, the expression levels of Zonula-1 and occludin were detected by immunofluorescence, including the plasma FITC-dextran 4000 concentration, to evaluate intestinal barrier permeability. However, ELISA measured the expression of inflammatory factors to reflect intestinal inflammation in mice. Investigations showed that the IRAK 1/4 inhibitor significantly reduced clinical symptoms and pathological DSS-induced colitis damage in mice and then inhibited the cytoplasmic and nuclear translocation of NF-κB p65, including the phosphorylation of IκBα and reduction in downstream inflammatory factor production. Therefore, we established that the IRAK1/4 inhibitor effectively improves colitis induced by DSS, partly by inhibiting the TLR4/NF-κB pathway, reducing inflammation, and maintaining the integrity of the colonic barrier.

Application of Demirjian's and Cameriere's Method in Dental Age Estimation of 8-16 Year Old Adolescents from Hunan Han Nationality

Abstract

Objective To apply Demirjian's and Cameriere's method for dental age estimation of adolescents from Hunan Han nationality, and compare the accuracy of the two methods. Methods A total of 480 orthopantomograms of?8-16 year?old adolescents from Hunan Han nationality?with no special diseases and good nutritional status were collected?by Xiangya Stomatological Hospital of Central South University from January, 2016 to July, 2017, among them 236 males and 244 females. The dental age of each adolescent was determined by Demirjian's method and Cameriere's method, respectively, and the paired t-test of the estimated dental age and the chronological age determined by the two methods was conducted by SPSS 20.0 software to compare the difference between estimated dental age and chronological age. Results Mean chronological age of males and females was 11.91 and 11.88 years, respectively. The estimated dental age determined by Demirjian's method showed an underestimate of chronological age by an average of 0.11 years （males） and 0.15 years （females）, while the estimated dental age determined by Cameriere's method showed an underestimate of chronological age by an average of 0.83 years （males） and 0.72 years （females）. Conclusion Demirjian's method is more accurate than Cameriere's method in dental age estimation of adolescents from Hunan Han nationality, therefore more suitable for dental age estimation of adolescents in this region.

[Research Progress of Vitreous Humor Detection Technique on Estimation of Postmortem Interval]

Estimation of postmortem interval （PMI） plays a crucial role in forensic study and identification work. Because of the unique anatomy location, vitreous humor is considered to be used for estima- ting PMI, which has aroused interest among scholars, and some researches have been carried out. The detection techniques of vitreous humor are constantly developed and improved which have been gradually applied in forensic science, meanwhile, the study of PMI estimation using vitreous humor is updated rapidly. This paper reviews various techniques and instruments applied to vitreous humor detection, such as ion selective electrode, capillary ion analysis, spectroscopy, chromatography, nano-sensing technology, automatic biochemical analyser, flow cytometer, etc., as well as the related research progress on PMI estimation in recent years. In order to provide a research direction for scholars and promote a more accurate and efficient application in PMI estimation by vitreous humor analysis, some inner problems are also analysed in this paper.

Genetic Polymorphisms of 21 STR Loci in Hunan Province-based Han Population

OBJECTIVES

To investigate the genetic polymorphisms of 21 short tandem repeat （STR） loci （D3S1358, D13S317, D7S820, D16S539, Penta E, D2S441, TPOX, TH01, D2S1338, CSF1PO, Penta D, D10S1248, D19S433, vWA, D21S11, D18S51, D6S1043, D8S1179, D5S818, D12S391 and FGA）.

METHODS

A total of 560 blood samples were collected from unrelated healthy individuals of Han population in Hunan Province. Chelex-100 extraction method was applied to the extraction of genomic DNA, and an AGCU EX22 Kit and 9700 STR amplification was used in amplification reactions. The products were separated and analyzed on 310 Genetic Analyzer.

RESULTS

A total of 248 alleles were observed, the allelic frequencies ranging from 0.001 to 0.518. Observation of genotype distributions for each locus showed no deviations from Hardy-Weinberg equilibrium except Penta E （P=0.023）. The combined power of discrimination, combined power of exclusion, and combined matching probability of the 21 STR loci were approximately 0.999 999 999 999 999 999 999 999 8, 0.999 999 998, and 1.36×10⁻²⁵, respectively.

CONCLUSIONS

The 21 STR loci show high polymorphisms in the Han population, which can provide valuable data and a theoretical basis for forensic individual identification and paternity testing.

The Origin and Development of Medical Jurisprudence in Xiangya

The origin of medical jurisprudence in China can be traced back to as early as 1920s, and since then, the discipline has undergone a great development. This paper, based on the disciplinary development of medical jurisprudence at Xiangya School of Medicine, illustrates its evolution in three aspects covering the scientific and theoretic foundation, legal system and policy support. The current investigation reflected a glimpse of the modern forensic science in China, providing useful historical reference for the development of Chinese forensic science.

Lung recruitment maneuver during proportional assist ventilation of preterm infants with acute respiratory distress syndrome

OBJECTIVE

To investigate the effect of lung recruitment maneuver (LRM) with positive end-expiratory pressure (PEEP) on oxygenation and outcomes in preterm infants ventilated by proportional assist ventilation (PAV) for respiratory distress syndrome (RDS).

STUDY DESIGN

Preterm infants on PAV for RDS after surfactant randomly received an LRM (group A, n=12) or did not (group B, n=12). LRM entailed increments of 0.2 cm H2O PEEP every 5 min, until fraction of inspired oxygen (FiO2)=0.25. Then PEEP was reduced and the lung volume was set on the deflation limb of the pressure/volume curve. When saturation of peripheral oxygen fell and FiO2 rose, we reincremented PEEP until SpO2 became stable.

RESULT

Group A and B infants were similar: gestational age 29.5 ± 1.0 vs 29.4 ± 0.9 weeks; body weight 1314 ± 96 vs 1296 ± 88 g; Silverman Anderson score for babies at start of ventilation 8.6 ± 0.8 vs 8.2 ± 0.7; initial FiO2 0.56 ± 0.16 vs 0.51 ± 0.14, respectively. The less doses of surfactant administered in group A than that in group B (P<0.05). Groups A and B showed different max PEEP during the first 12 h of life (8.4 ± 0.5 vs 6.7 ± 0.6 cm H2O, P=0.00), time to lowest FiO2 (101 ± 18 versus 342 ± 128 min; P=0.000) and O2 dependency (7.83 ± 2.04 vs 9.92 ± 2.78 days; P=0.04). FiO2 levels progressively decreased (F=43.240, P=0.000) and a/AO2 ratio gradually increased (F=30.594, P=0.000). No adverse events and no differences in the outcomes were observed.

CONCLUSION

LRM led to the earlier lowest FiO2 of the first 12 h of life and a shorter O2 dependency.

Altered expression of Krüppel-like factor 4 and β-catenin in human gastric cancer

The effects of the interaction between KLF4 and β-catenin may be significant in human carcinogenesis and tumor development. This study aimed to determine whether the expression of KLF4 and β-catenin in gastric cancer tissues is associated with clinicopathological characteristics. Western blot analysis and immunohistochemistry were performed to detect KLF4 and β-catenin expression in tumor and corresponding non-cancerous tissues from 49 patients. The data revealed that KLF4 expression was significantly reduced in gastric cancer tissues compared with normal tissues. By contrast, the expression of the β-catenin protein was significantly increased in all tumor tissues, but was not expressed in distant normal mucosae. The altered expression of the KLF4 and β-catenin proteins was associated with advanced tumor stage and gastric cancer. In addition, the expression of the KLF4 and β-catenin proteins was inversely associated in moderately differentiated human gastric cancers. This study showed that β-catenin expression is significantly increased and KLF4 protein expression is markedly decreased in gastric cancer tissues, thus showing that the expression of KLF4 is inversely correlated with that of β-catenin in gastric cancer. The altered expression of the two proteins is associated with advanced tumor stage in gastric cancer.

Evaluation of a new Spin-echo diffusion-weighted sequence on a 0.35 T open magnetic resonance imaging (MRI)-system: first experiences within 3 h after acute stroke

In acute stroke, diffusion-weighted magnetic resonance imaging helps to select patients who are eligible for thrombolysis, but is almost exclusively implemented on closed-bore scanners, which make monitoring of patients difficult. We developed and tested a cardiac gated Spin-echo diffusion-weighted sequence with prescan finetrim and motion correction on an open system with 0.35 T. Nineteen stroke patients appropriate for thrombolytic therapy by clinical criteria were enrolled in a prospective study on an intention-to-treat basis. In all but one patient, computed tomography and magnetic resonance imaging including the new diffusion-weighted sequence were performed within 3 h after symptom onset. Images were evaluated for acute cerebral ischemia and hemorrhage by two radiologists blinded to clinical information. Magnetic resonance imaging required a mean total acquisition time of 26 min. Sensitivity for early infarction was 94% in diffusion-weighted imaging and 73% in computed tomography. Six patients were excluded from thrombolysis due to an infarct size of more than 1/3 of the territory of the middle cerebral artery exclusively diagnosed with diffusion-weighted imaging. Hemorrhage was recognised by both, magnetic resonance imaging and computed tomography. We conclude that in acute stroke, diffusion-weighted imaging with an open system at 0.35 T is practicable. The implemented sequence reliably demonstrated the size of the infarction and improved the selection of patients who are eligible for thrombolysis.

A method for the calculation of currents on shielded gradient coils

Alternate expressions for the current density on the shielding surface of a gradient coil are derived for cylindrical, planar, and hyperbolic gradient coils. For the planar and hyperbolic geometries, these expressions allow more rapid high-precision calculations of current densities than the conventional solution.

Optimized ultra-fast imaging sequence (OUFIS)

The DUFIS sequence can make ultra-fast images (approximately 10 ms) without the use of rapidly switched gradients. The RF excitation sequence is spatially selective so that only a small fraction of the magnetization in each imaging pixel is used which produces a poor imaging signal to noise ratio (SNR). We have developed several alternative RF sequences that use RF pulses with multiple phases, and also with just 0 degrees and 180 degrees phases to excite almost all the magnetization in a pixel and greatly improve the SNR. The optimization of these pulse sequences (now called OUFIS) have been conducted both analytically and by numerical searches, with various linear and nonlinear models. Both theoretical and computational methods used in the optimizations are described in detail. Preliminary experimental results are briefly presented with several possible applications of the OUFIS excitation sequences suggested.