[Study on formulation of standard limits for trichloroethylene and tetrachloroethylene in "Standards for indoor air quality（GB/T 18883-2022）" in China]

There are clear indoor air pollution sources of trichloroethylene and tetrachloroethylene. A large number of epidemiological evidence has confirmed their carcinogenic toxicity and non-carcinogenic toxicity. Several countries and international organizations have paid attention to indoor air trichloroethylene and tetrachloroethylene. It has been also assessed that there should be certain potential health risk of indoor air trichloroethylene and tetrachloroethylene in China. Based on the latest research results of health risk assessment of indoor air trichloroethylene and tetrachloroethylene, the "Standards for indoor air quality (GB/T 18883-2022)" added trichloroethylene and tetrachloroethylene as indicators. The index limit of trichloroethylene is 6 μg/m3 for an 8-hour average concentration. The index limit of tetrachloroethylene is 120 μg/m3 for an 8-hour average concentration. The technical contents related to the determination of the standard limits of trichloroethylene and tetrachloroethylene in indoor air were analyzed and discussed, including the sources, the exposure, the health effects, the determination of the limit values, and the recommendations for standard implementation. It also proposed recommendations for the implementation of"Standards for indoor air quality (GB/T 18883-2022)".

Stochastic simulation of hydrogen-oxygen auto-ignition at the microscale

A hybrid stochastic simulation method is developed to study H2-O2 auto-ignition at the microscale. Simulation results show that the discrete and stochastic characteristics of reaction collisions have notable impacts on the ignition process, particularly in the early stages when only a few radicals exist. The statistical properties of ignition delay time, which reflect the accumulated stochasticity during ignition, are obtained and analyzed for different initial temperatures and total molecular numbers. It is found that the average and standard deviation of ignition delay time increase as the total molecular number decreases, with this phenomenon being particularly pronounced near the crossover temperature. When the total molecular number is sufficiently small, the chain initiation reaction becomes crucial to the stochastic properties, as its average firing time exhibits an inverse proportionality to the total molecular number. As the total molecular number increases, the influence of other chain reactions intensifies, causing the power law relation between standard deviation and total molecular number to shift from -1 power to -0.5 power. Owing to different chain reaction paths for high- and low-temperature auto-ignition, the strongest relative fluctuation occurs near the crossover temperature. A theoretical equation for the standard deviation of ignition delay time is obtained based on dimensional analysis, giving excellent agreement with the simulation results in both high- and low-temperature modes.

[The North-South difference of the relationship between cold spells and mortality risk of cardiovascular diseases in China]

Objective: To analyze the North-South difference of the relationship between cold spells and mortality risk of cardiovascular diseases in China. Methods: The time series analysis method was used to collect the daily counts of cardiovascular mortality data, meteorological data and PM_2.5 concentration in the cold season (November to March of the following year) from January 1, 2013 to December 31, 2018 in 280 districts and counties in China. The non-constrained distributed lag linear model was used to analyze the relationship between cold spells and mortality risk of cardiovascular diseases and its North-South difference in China. Results: From 2013 to 2018, the mean of daily average temperature of the cold season in 280 districts and counties was 5.4 ℃. The mean of daily average relative humidity was 64.4%, and the mean of daily average PM_2.5 concentration was 73.7 μg/m³. The average cold spell days in each county was 11.7 days per year,the mean of daily average temperature on cold spell days was (-2.4±6.7) ℃, and M (Q₁, Q₃) was -1.5 (-5.1, 1.1) ℃. The average of daily number of cardiovascular disease deaths in each county/district was (6±5) cases, and M (Q₁, Q₃) was 5 (2, 8) cases. The percentage change (95%CI) in the South was 4.94% (3.69%, 6.20%) (lag 0 d), higher than that in the North [the percentage change (95%CI) was 1.49% (1.14%-1.84%) (lag 0-7 d)]. In the North, the mortality risk of ≥75 years old was relatively low among three age groups, with a percentage change (95%CI) about 1.63% (1.33%-1.93%) (lag 0-21 d). In the South, the mortality risk of ≥ 75 years old was relatively high among three age groups, with a percentage change (95%CI) about 5.18% (3.78%-6.59%) (lag 0 d). Conclusion: The mortality risk of cardiovascular diseases caused by cold spells in the South is higher than that in the North of China, and the risk peak occurs earlier in the South.

[Associations between personal fine particulate matter and blood lipid profiles: A panel study in Chinese people aged 60-69 years]

Objective: To explore the association between short-term exposures to fine particulate matter (PM_2.5) on blood lipids in the elderly. Methods: In this panel study, five repeated measurements were performed on 76 people aged 60-69 in Jinan city. Each participant had a PM_2.5 monitor for 72 hours before each health examination, including a questionnaire survey, physical examination, and biological sample collection. Serum triglycerides (TG), total cholesterol (TC), high-density lipoprotein cholesterol (HDL-C), and low-density lipoprotein cholesterol (LDL-C) were examined, and non-HDL-C concentrations were calculated by subtracting HDL-C from TC. The generalized linear mixed-effects model was used to quantify the association of personal PM_2.5 exposure at different lag with blood lipids and dyslipidemia. Results: The age of 70 participants was (65.0±2.8) years, of which 48.6% (34/70) were males. The BMI of participants was (25.0±2.5) kg/m². Their TC, TG, LDL-C, HDL-C, and non-HDL-C concentrations were (5.75±1.32), (1.55±0.53), (3.27±0.94), (1.78±0.52), and (3.97±1.06) mmol/L, respectively. Generalized linear mixed-effects model showed that after adjusting for confounding factors, at lag 72 hours, each 10 μg/m³ increase in PM_2.5 was associated with the percentage change in TC, LDL-C, HDL-C and non-HDL-C about 1.77% (95%CI: 1.22%-2.32%), 1.90% (95%CI: 1.18%-2.63%), 1.99% (95%CI: 1.37%-2.60%) and 1.74% (95%CI: 1.11%-2.37%), and the OR values (95%CI) of hypercholesterolemia, hypertriglyceridemia and hyperbetalipoproteinemia were 1.11 (1.01-1.22), 1.33 (1.03-1.71) and 1.15 (1.01-1.31), respectively. Conclusion: There is a significant association of short-term PM_2.5 exposure with the concentration of blood lipids and the risk of dyslipidemia in the elderly.

[Evaluation of the fresh air purification system in the classroom under heavy pollution weather]

Evaluate the effect of the fresh air purification system on the improvement of indoor PM_2.5 levels in a primary school classroom in Jinan City, Shandong Province. Our purpose is to explore the optimal operating time of the fresh air system and the main factors that affect the fresh air purification system to improve indoor air quality. From December 9, 2019 to December 10, 2019, two classrooms of the same area on the third floor of a primary school building in Jinan City, Shandong Province were selected as monitoring points. During the operation of the fresh air purification system, the PM_2.5 concentration in the classroom is reduced by an average of 48.1%-61.5% compared to the outdoor PM_2.5 concentration. After running for about 2 hours, the indoor PM_2.5 concentration decreased to a relatively stable concentration level. The operating time of the fresh air purification system, student activities between classes, indoor temperature, indoor relative humidity, and outdoor PM_2.5 concentration are important factors that affect the indoor particulate removal rate. In the case of a certain amount of fresh air and indoor area, closing doors and windows and appropriately extending the operation time of the fresh air purification system can improve the air quality in the classroom to a certain extent and protect the health of students.

miR-874 inhibits gastric cancer cell proliferation by targeting SPAG9

Background

microRNAs (miRNAs) play essential roles in the development and progression of gastric cancer (GC). Although aberrant miR-874 expression has been reported in various human cancers, its role in GC remains obscure.

Methods

miR-874 expression was assessed by real-time quantitative polymerase chain reaction (RT-qPCR) in 62 matched GC and adjacent normal tissues, as well as in GC cell lines and immortalized human gastric epithelial cells. CCK8 assay, colony formation assay, and flow cytometry were used to assess the role of miR-874 in GC cell proliferation and apoptosis in vitro. Additionally, to determine the effects of miR-874 on GC cell proliferation and apoptosis in vivo, BALB/c nude mice were injected with GC cells transfected with a miR-874 mimic. The role of miR-874 in SPAG9 expression was assessed by luciferase assay, Western blotting, and RT-qPCR.

Results

miR-874 was downregulated in GC cell lines and tissues. miR-874 overexpression in GC cells led to inhibition of cell proliferation and induction of apoptosis. Moreover, SPAG9 was identified as a direct miR-874 target, the expression of which was suppressed by miR-874. SPAG9 overexpression markedly promoted GC cell proliferation.

Conclusions

miR-874 inhibited cell proliferation and induced apoptosis in GC cells. SPAG9 downregulation was crucial for the tumor-suppressive effects of miR-874. Hence, the miR-874/SPAG9 axis could serve as a novel therapeutic target in GC.

[The impact of persistent high ambient fine particulate matters exposures on mortality in the 40 districts/counties of China, 2013-2015]

Objective: To investigate the impact of persistent high ambient fine particulate matters (PM(2.5)) exposures on mortality in the polluted areas of 40 districts/counties in China. Methods: Using a convenient sampling method, we selected 40 districts/counties as research sites from the Beijing-Tianjin-Hebei Metropolitan Region, the Yangtze River Delta, the Pearl River Delta, and Heilongjiang, Shanxi, and Sichuan province. The daily concentrations of PM(2.5), meteorological data and population death data from January 1, 2013 to December 31, 2015 were collected. The six persistent PM(2).5 pollution episode scenarios were defined by the average daily concentration of PM(2.5) (75 μg/m(3), P(75) and P(90) of the average daily concentration of each district/county respectively) and the duration (≥2 days or 3 days). Generalized linear models and meta analyses were used to explore the impact of PM(2.5) pollution episodes on mortality in 40 districts/counties. Results: The mean±SD and P(50) (P(25), P(75)) of average daily temperature, relative humidity and PM(2.5) were (15.26±10.48) ℃, 17.20 (7.50, 23.70) ℃, (67.31±19.26)%, 72.00% (57.00%, 81.00%), (72.81±60.93) μg/m(3) and 55.38 (33.77, 91.45) μg/m(3), respectively in 40 districts/counties during 2013-2015. The average number of non-accidental, cardiovascular and cerebrovascular diseases deaths per day were (12±7), (5±4) and (2±2) in each district/county, respectively. When the daily concentrations of PM(2.5) were ≥75 μg/m(3) (≥2 days), ≥P(75) (≥2 days), ≥P(90) (≥2 days), ≥75 μg/m(3) (≥3 days), and ≥P(75) (≥3 days), the excess risk (95%CI) of the total non-accidental deaths and cardiovascular diseases deaths were 1.77% (0.89%,2.66%), 2.69% (1.06%,4.35%), 1.67% (0.59%,2.76%), 2.31% (0.67%, 3.97%), 0.71% (-0.75%, 2.20%), 1.95% (0.08%, 3.86%), 1.15% (0.12%, 2.18%), 1.85% (0.25%, 3.47%), 1.39% (0.15%, 2.64%), 2.29% (0.39%, 4.23%), respectively. Conclusion: Persistently high PM(2.5) exposures were associated with total non-accidental deaths and cardiovascular disease deaths.

[Estimating and projecting the acute effect of cold spells on excess mortality under climate change in Guangzhou]

Objective: To estimate future excess mortality attributable to cold spells in Guangzhou, China. Methods: We collected the mortality data and metrological data from 2009-2013 of Guangzhou to calculated the association between cold spell days and non-accidental mortality with GLM model. Then we projected future daily average temperatures (2020-2039 (2020s) , 2050-2069 (2050s) , 2080-2099 (2080s) ) with 5 GCMs models and 2 RCPs (RCP4.5 and RCP8.5) to identify cold spell days. The baseline period was the 1980s (1980-1999). Finally, calculated the yearly cold spells related excess death of 1980s, 2020s, 2050s, and 2080s with average daily death count of non-cold spell days, exposure-response relationship, and yearly number of cold spell days. Results: The average of daily non-accidental mortality in Guangzhou from 2009 to 2013 was 96, and the average of daily average was 22.0 ℃. Cold spell days were associated with 3.3% (95%CI: 0.4%-6.2%) increase in non-accidental mortality. In 1980s, yearly cold spells related deaths were 34 (95%CI: 4-64). In 2020s, the number will increase by 0-10; in 2050s, the number will increase by 1-9; and in 2080s, will increase by 1-9 under the RCP4.5 scenario. In 2020s, the number will increase by 0-9; in 2050s, the number will increase by 1-6; and in 2080s, will increase by 0-11 under the RCP8.5 scenario. Conclusion: The cold spells related non-accidental deaths in Guangzhou will increase in future under climate change.

[Simulation study of air quality health index in 5 cities in China: 2013-2015]

Objective: To construct the air quality health index (AQHI) by inclusion of air pollutants PM(2.5) and O(3) in Guangzhou, Shanghai, Xi' an, Beijing, Shenyang, and explore scientificity and feasibility of its application in China. Methods: The daily average concentrations of PM(2.5) and O(3) in air, and daily average mortality from 2013 to 2015 in the 5 cities in China, the exposure-response coefficients of PM(2.5) and O(3) and total mortality from Meta studies in China were used to construct local AQHI. The health risk levels of air pollution in the 5 cities were calculated and compared with the characteristics of single pollutant concentrationof PM(2.5) or O(3). Results: In the 5 cities, the average concentration of PM(2.5) was highest in Beijing (82 μg/m(3)) and lowest in Guangzhou (46 μg/m(3)). And the average concentration of O(3) was highest in Shanghai (72 μg/m(3)) and lowest in Xi' an (45 μg/m(3)). In all the cities, the average concentration of PM(2.5) was highest in winter and lowest in summer. In summer, the average concentration of O(3) was lowest. But the health risk level of AQHI showed that the 5 cities had higher frequency of low or medium risk averagely. And Beijing had the highest frequency of high risk in summer (5.69%). Xi' an had the highest frequency of extremely high risk in winter (1.63%). Conclusions: In this study, AQHI could be constructed by using air PM(2.5) and O(3) concentration data which can be obtained in many areas in China. The application of this index is scientific and feasible in China.

Genetic variation of Sargassum horneri populations detected by inter-simple sequence repeats

The seaweed Sargassum horneri is an important brown alga in the marine environment, and it is an important raw material in the alginate industry. Unfortunately, the fixed resource that was originally reported is now reduced or disappeared, and increased floating populations have been reported in recent years. We sampled a floating population and 4 fixed cultivated populations of S. horneri along the coast of Zhejiang, China. Inter-simple sequence repeat (ISSR) markers were applied in this research to analyze the genetic variation between floating populations and fixed cultivated populations of S. horneri. In total, 220 loci were amplified with 23 ISSR primers. The percentage of polymorphic loci within each population ranged from 53.64 to 95.45%. The highest diversity was observed in population 3, which was the local species that was suspension cultured in the lab and then fixed cultivated in the Nanji Islands before sampling. The lowest diversity was obtained in the floating population 4. The genetic distances among the 5 S. horneri populations ranged from 0.0819 to 0.2889, and the distance tendency confirmed the genetic diversity. The results suggest that the floating population had the lowest genetic diversity and could not be joined into the cluster branch of the fixed cultivated populations.

A point mutation in the cysteine-rich domain of glycoprotein (GP) IIIa results in the expression of a GPIIb-IIIa (alphaIIbbeta3) integrin receptor locked in a high-affinity state and a Glanzmann thrombasthenia-like phenotype

This article reports a Glanzmann thrombasthenia (GT) patient, N.M., with a point mutation in the third cysteine-rich repeat of beta3-integrin or platelet glycoprotein (GP) IIIa, leading to the expression of a constitutively activated fibrinogen receptor. The diagnosis of GT was based on a severely reduced platelet-aggregation response to a series of agonists and approximately 20% of surface-expressed GPIIb-IIIa. The patient's GPIIb-IIIa constitutively expressed epitopes recognized by antibodies to ligand-induced binding sites (LIBS) and also spontaneously bound the fibrinogen-mimetic antibody, PAC-1. Furthermore, significant amounts of bound fibrinogen were detected on his platelets ex vivo. No signs of platelet activation were observed on sections of unstimulated platelets from N.M. by electron microscopy. Immunogold labeling highlighted the presence of surface-bound fibrinogen but revealed platelet heterogeneity with regard to the surface density. When the patient's platelets were stimulated by thrombin-receptor activating peptide, amounts of surface-expressed GPIIb-IIIa increased and the aggregation response improved, although it failed to normalize. Platelets from N.M. were able to adhere and spread on immobilized fibrinogen. Sequence analysis of genomic DNA from N.M. revealed a homozygous g1776T>C mutation in GPIIIa, leading to a Cys560Arg amino acid substitution. A stable Chinese hamster ovary (CHO) cell line was prepared expressing surface GPIIb-Arg560IIIa. Like platelets from the patient, GPIIb-Arg560IIIa-transfected CHO cells constitutively bound LIBS antibodies and PAC-1. They also showed an enhanced ability to adhere on surface-bound fibrinogen. Overall, these data demonstrate that a gain-of-function mutation can still be associated with a thrombasthenic phenotype even though platelets show spontaneous fibrinogen binding.

Platelet endothelial cell adhesion molecule-1 (PECAM-1) is a target glycoprotein in drug-induced thrombocytopenia

Drug-induced immune thrombocytopenia (DITP) is a serious complication of drug treatment. Previous studies demonstrated that most drug-dependent antibodies (DDAbs) react with the platelet membrane glycoprotein (GP) complexes IIb/IIIa and Ib/IX/V. We analyzed the sera from 5 patients who presented with DITP after intake of carbimazole. Notably, thrombocytopenia induced by carbimazole was relatively mild in comparison to patients with DITP induced by quinidine. The sera reacted with platelets in an immunoassay on addition of the drug. In immunoprecipitation experiments with biotin-labeled platelets and endothelial cells, reactivity with the platelet endothelial cell adhesion molecule-1 (PECAM-1, CD31) could be demonstrated, whereas neither GPIIb/IIIa nor GPIb/IX was precipitated in the presence of the drug. These results could be confirmed by GP-specific immunoassay (MAIPA) using monoclonal antibodies (mabs) against PECAM-1. In addition, the binding of DDAbs could be abolished by preincubation with soluble recombinant PECAM-1. Carbimazole-dependent antibodies showed similar reactivity with platelets carrying the Leu(125) and Val(125) PECAM-1 isoforms, indicating that this polymorphic structure, which is located in the first extracellular domain, is not responsible for the epitope formation. Binding studies with biotin-labeled mutants of PECAM-1 and analysis of sera with mabs against different epitopes on PECAM-1 in MAIPA assay suggested that carbimazole-dependent antibodies prominently bound to the second immunoglobulin homology domain of the molecule. Analysis of 20 sera from patients with quinidine-induced thrombocytopenia by MAIPA assay revealed evidence that DDAbs against PECAM-1 are involved in addition to anti-GPIb/IX and anti-GPIIb/IIIa. We conclude that PECAM-1 is an important target GP in DITP. (Blood. 2000;96:1409-1414)

Antibodies against the first Ig-like domain of human platelet endothelial cell adhesion molecule-1 (PECAM-1) that inhibit PECAM-1-dependent homophilic adhesion block in vivo neutrophil recruitment

Platelet endothelial cell adhesion molecule (PECAM-1), a member of the Ig superfamily, is found on endothelial cells and neutrophils and has been shown to be involved in the migration of leukocytes across the endothelium. Adhesion is mediated, at least in part, through binding interactions involving its first N-terminal Ig-like domain, but it is still unclear which sequences in this domain are required for in vivo function. Therefore, to identify functionally important regions of the first Ig-like domain of PECAM-1 that are required for the participation of PECAM-1 in in vivo neutrophil recruitment, a panel of mAbs against this region of PECAM-1 was generated and characterized in in vitro adhesion assays and in an in vivo model of cutaneous inflammation. It was observed that mAbs that disrupted PECAM-1-dependent homophilic adhesion in an L cell aggregation assay also blocked TNF-alpha-induced intradermal accumulation of neutrophils in a transmigration model using human skin transplanted onto SCID mice. Localization of the epitopes of these Abs indicated that these function-blocking Abs mapped to specific regions on either face of domain 1. This suggests that these regions of the first Ig-like domain may contain or be close to binding sites involved in PECAM-1-dependent homophilic adhesion, and thus may represent potential targets for the development of antiinflammatory reagents.

Gene transfer into fetal baboon hematopoietic progenitor cells

We studied hematopoietic progenitors from fetal baboon blood, marrow, and liver at four time points (125, 140, 160, and 175 days) during the third trimester (gestation approximately 180 days) to determine if fetal baboons might be an appropriate model for in utero gene therapy of hematopoietic stem cells (HSCs). Cells were studied for expression of CD34, CD33, CD38, and HLA-DR, for progenitor content in colony-forming cell assays, and for susceptibility of CD34+ progenitors to retrovirus-mediated gene transfer. Throughout the third trimester, the frequency of CD34+ progenitors in blood and marrow appears to remain unchanged at approximately 0.6 and 5.0%, respectively. In liver, progenitors progressively decrease to undetectable levels by day 175. The proportion of fetal baboon bone marrow and liver CD34+ cells expressing CD38 and HLA-DR appears to increase with increasing fetal age, similar to changes reported for human cord blood CD34+ cells. In fetal baboon blood the proportion of CD34+ cells expressing CD33 appears to decrease with increasing gestational age, also similar to changes reported for human cord blood cells. Progenitors from human cord blood and baboon fetal tissues were similarly susceptible to transduction by the gibbon ape leukemia pseudotyped retroviral vector LAPSN(PG13) containing the genes for human placental alkaline phosphatase (AP) and the bacterial neomycin phosphotransferase (neo). Fetal baboon and human hematopoietic progenitor cells undergo similar phenotypic changes during the third trimester of fetal development and are similarly susceptible to retrovirus-mediated gene transfer. The fetal baboon may be a model in which approaches to mobilization and gene transfer into fetal HSCs can be studied.

Cell surface glycosaminoglycans do not serve as ligands for PECAM-1. PECAM-1 is not a heparin-binding protein

Previous studies have suggested that PECAM-1 mediates cellular interactions via both homophilic and heterophilic adhesive mechanisms. Cell surface glycoaminoglycans have been implicated as one of the heterophilic ligands for PECAM-1. To determine whether PECAM-1 is capable of interacting directly with glycosaminoglycans, we examined the adhesive properties of multiple monovalent and multivalent forms of this adhesion molecule. We found that the binding of a bivalent PECAM-1/IgG chimeric protein or multivalent PECAM-1-containing proteoliposomes to multiple different cell lines was 1) strictly dependent upon cell surface expression of PECAM-1 and 2) unaffected by the presence of excess heparin or heparan sulfate. The extracellular domain of PECAM-1 failed to interact specifically with heparin-Sepharose, 3H-labeled heparin, or a heparin-bovine serum albumin conjugate. In addition, an amino acid sequence motif inadvertently created by the juxtaposition of PECAM-1 and IgG sequences within the hinge region of certain PECAM-1/IgG chimeric constructs was found to confer glycosaminoglycan binding properties not normally present within the extracellular domain of the native molecule. Together, these data suggest that the mechanism by which heparin is able to affect PECAM-1-dependent cell-cell adhesion is indirect and occurs via inhibition of events that occur downstream from PECAM-1 engagement.

Individually distinct Ig homology domains in PECAM-1 regulate homophilic binding and modulate receptor affinity

PECAM-1 (CD31) is a 130-kDa member of the immunoglobulin (Ig) gene superfamily that is constitutively expressed at high concentration at endothelial cell intercellular junctions and at moderate density on the surface of circulating leukocytes and platelets. Recent in vitro and in vivo studies have shown the PECAM-1 plays a central role in mediating the extravasation of leukocytes from the vessel wall in response to inflammatory mediators. To study the binding characteristics of PECAM-1, phospholipid vesicles were prepared and examined by flow cytometry and immunofluorescence microscopy for their ability to associate with each other and with cells. Proteoliposomes containing high concentrations of PECAM-1 interacted homophilically with each other, forming large self-aggregates. PECAM-1 proteoliposomes, as well as soluble bivalent PECAM-1 in the form of a PECAM-1/IgG immunoadhesin, associated homophilically with cells expressing human, but not murine, PECAM-1. This binding could be completely inhibited by monoclonal antibody Fab fragments specific for Ig homology Domain 1 or Domains 1 + 2. Binding studies using cells expressing human PECAM-1 deletion mutants and murine/human chimeras confirmed that both Ig Domains 1 and 2 were both necessary and sufficient for homophilic binding. In contrast, engagement of membrane-proximal Domain 6 with monoclonal antibody Fab fragments had the opposite effect and augmented the binding of PECAM-1 proteoliposomes to cells. Thus, PECAM-1, like certain integrins, appears to be capable of antibody-induced conformational changes that alter affinity for its ligand. Similar changes induced by physiologic stimuli could be important in regulating the function of PECAM-1 in vascular cells.