The reduction of nitrate to nitrite by the oral microbiota has been proposed to be important for oral health and results in nitric oxide formation that can improve cardiometabolic conditions. Studies of bacterial composition in subgingival plaque suggest that nitrate-reducing bacteria are associated with periodontal health, but the impact of periodontitis on nitrate-reducing capacity (NRC) and, therefore, nitric oxide availability has not been evaluated. The current study aimed to evaluate how periodontitis affects the NRC of the oral microbiota. First, 16S rRNA sequencing data from five different countries were analyzed, revealing that nitrate-reducing bacteria were significantly lower in subgingival plaque of periodontitis patients compared with healthy individuals (P < 0.05 in all five datasets with n = 20-82 samples per dataset). Secondly, subgingival plaque, saliva, and plasma samples were obtained from 42 periodontitis patients before and after periodontal treatment. The oral NRC was determined in vitro by incubating saliva with 8 mmol/L nitrate (a concentration found in saliva after nitrate-rich vegetable intake) and compared with the NRC of 15 healthy individuals. Salivary NRC was found to be diminished in periodontal patients before treatment (P < 0.05) but recovered to healthy levels 90 days post-treatment. Additionally, the subgingival levels of nitrate-reducing bacteria increased after treatment and correlated negatively with periodontitis-associated bacteria (P < 0.01). No significant effect of periodontal treatment on the baseline saliva and plasma nitrate and nitrite levels was found, indicating that differences in the NRC may only be revealed after nitrate intake. Our results suggest that an impaired NRC in periodontitis could limit dietary nitrate-derived nitric oxide levels, and the effect on systemic health should be explored in future studies.
Humans ; Nitrates ; Nitric Oxide ; Nitrites ; RNA, Ribosomal, 16S/genetics* ; Periodontitis/microbiology* ; Bacteria ; Dental Plaque/microbiology* ; Saliva/microbiology* ; Microbiota/genetics*

BACKGROUND: Metabolic Dysfunction-associated Steatotic Liver Disease (MASLD) has become a global epidemic, and air pollution has been identified as a potential risk factor. This study aims to investigate the non-linear relationship between ambient air pollution and MASLD prevalence. METHOD: In this cross-sectional study, participants undergoing health checkups were assessed for three-year average air pollution exposure. MASLD diagnosis required hepatic steatosis with at least 1 out of 5 cardiometabolic criteria. A stepwise approach combining data visualization and regression modeling was used to determine the most appropriate link function between each of the six air pollutants and MASLD. A covariate-adjusted six-pollutant model was constructed accordingly. RESULTS: A total of 131,592 participants were included, with 40.6% met the criteria of MASLD. "Threshold link function," "interaction link function," and "restricted cubic spline (RCS) link functions" best-fitted associations between MASLD and PM_2.5, PM₁₀/CO, and O₃ /SO₂/NO₂, respectively. In the six-pollutant model, significant positive associations were observed when pollutant concentrations were over: 34.64 µg/m³ for PM_2.5, 57.93 µg/m³ for PM₁₀, 56 µg/m³ for O₃, below 643.6 µg/m³ for CO, and within 33 and 48 µg/m³ for NO₂. The six-pollutant model using these best-fitted link functions demonstrated superior model fitting compared to exposure-categorized model or linear link function model assuming proportionality of odds. CONCLUSION Non-linear associations were found between air pollutants and MASLD prevalence. PM_2.5, PM₁₀, O₃, CO, and NO₂ exhibited positive associations with MASLD in specific concentration ranges, highlighting the need to consider non-linear relationships in assessing the impact of air pollution on MASLD.
Humans ; Nitrogen Dioxide ; Cross-Sectional Studies ; Air Pollution/analysis* ; Air Pollutants/analysis* ; Particulate Matter/analysis* ; Liver Diseases ; Environmental Exposure/analysis*

Sodium nitrite (SN, NaNO2) is a water-soluble, white-yellow crystalline powder with broad applications in food preservation, automotive maintenance, and animal control. It is a strong oxidizing agent that can oxidize hemoglobin iron (Fe) to its oxidized state, leading to methemoglobin formation. An increasing trend of suicide cases by SN ingestion has been reported globally following its popularization in online suicide forums providing detailed instructions of its use solely or as part of a “suicide kit.” We report a case of a 21-year-old male who was found continuously vomiting, with blood per orem and cyanosis of the mouth and digits. Within minutes of the onset of symptoms, the patient lost consciousness and was pronounced dead on arrival at the nearest emergency room. Autopsy findings showed lip erosions, hemorrhage, and perioral and peripheral cyanosis. Internal examination showed characteristic bright red muscle discoloration, dark brown arterial blood, red-brown congested visceral organs, and hyperemic esophageal and gastric mucosa. Methemoglobin studies from sampled arterial blood showed elevated levels (17.5%). Further investigation of the decedent’s belongings, social media posts, and recent online purchases reinforced the intentional sodium nitrite ingestion. While there are plenty of reported SN poisoning in suicide cases internationally, limited reports have been published locally. Death by SN poisoning is preventable with Methylene blue. The role of forensic pathologists through autopsy may be the last chance to detect such cases. The lack of systemic death investigation, experts, and local laboratories to reliably detect the signs of SN poisoning may have affected the low detection rate of cases locally. Further reporting of cases can raise the awareness of medical professionals that is fundamental to the ultimate saving of lives.

The present study aimed to investigate the protective effect of S-propargyl-cysteine (SPRC) on atherosclerosis progression in mice. A mouse model of vulnerable atherosclerotic plaque was created in ApoE^-/- mice by carotid artery tandem stenosis (TS) combined with a Western diet. Macrophotography, lipid profiles, and inflammatory markers were measured to evaluate the antiatherosclerotic effects of SPRC compared to atorvastatin as a control. Histopathological analysis was performed to assess the plaque stability. To explore the protective mechanism of SPRC, human umbilical vein endothelial cells (HUVECs) were cultured in vitro and challenged with oxidized low-density lipoprotein (ox-LDL). Cell viability was determined with a Cell Counting Kit-8 (CCK-8). Endothelial nitric oxide synthase (eNOS) phosphorylation and mRNA expression were detected by Western blot and RT-qPCR respectively. The results showed that the lesion area quantified by en face photographs of the aortic arch and carotid artery was significantly less, plasma total cholesterol (TC) and low-density lipoprotein cholesterol (LDL-C) were reduced, plaque collagen content was increased and matrix metalloproteinase-9 (MMP-9) was decreased in 80 mg/kg per day SPRC-treated mice compared with model mice. These findings support the role of SPRC in plaque stabilization. In vitro studies revealed that 100 μmol/L SPRC increased the cell viability and the phosphorylation level of eNOS after ox-LDL challenge. These results suggest that SPRC delays the progression of atherosclerosis and enhances plaque stability. The protective effect may be at least partially related to the increased phosphorylation of eNOS in endothelial cells.
Animals ; Humans ; Mice ; Atherosclerosis ; Cholesterol/metabolism* ; Cysteine/pharmacology* ; Human Umbilical Vein Endothelial Cells/metabolism* ; Lipoproteins, LDL/pharmacology* ; Nitric Oxide Synthase Type III/metabolism* ; Phosphorylation ; Plaque, Atherosclerotic/pathology*

Objective: To investigate the clinical significance of endothelin A receptor (ETAR) expression in high-grade serous ovarian carcinoma (HGSOC). To design ETAR carboxyl terminal (ETAR-C) amino acids derived polypeptide and to study the inhibitory effect on ovarian epithelial carcinoma cells in vitro. Methods: (1) A total of 126 patients who received surgical treatment and were diagnosed with HGSOC by postoperative pathological examination in Central Hospital of Xuzhou from January 1, 2007 to December 31, 2017 were selected. All patients had completed clinicopathological data and follow-up data. Cancer tissue samples were collected and ETAR mRNA expression in HGSOC tissues was detected by reverse transcript-PCR. The clinical significance was analyzed. (2) ETAR-C fusion polypeptide was designed based on the sequence of carboxyl terminal amino acids of ETAR, expressed and purified in vitro. The effects of ETAR-C fusion polypeptide on migration and invasion ability of ovarian cancer SKOV3 and CAOV3 cells were detected by scratch test and invasion test, respectively. The effect of ETAR-C fusion polypeptide on chemosensitivity of cisplatin-resistant ovarian cancer SKOV3/cDDP and CAOV3/cDDP cells was determined by methyl thiazolyl tetrazolium (MTT) colorimetric assay. The effect of ETAR-C fusion polypeptide on β-arrestin-1 expression in ovarian cancer SKOV3 and CAOV3 cells was detected by western blot. Results: (1) The relative expression level of ETAR mRNA in HGSOC tissues was 18.6±5.1. Patients with HGSOC were divided into high ETAR mRNA expression (n=76) and low ETAR mRNA expression (n=50) with 61.7% as cut-off value analyzed by X-Tile software. High expression of ETAR mRNA was significantly correlated with abdominal water volume, platinum drug resistance, and cancer antigen 125 (CA₁₂₅) value in HGSOC patients (all P<0.05), but was not related to the age of patients with HGSOC and the size of postoperative residual lesions (all P>0.05). The 5-year progression free survival rates were 18.4% and 28.0%, and the 5-year overall survival rates were 38.2% and 52.0% in HGSOC patients with high and low ETAR mRNA expression respectively, there were statistically significant differences (P=0.046, P=0.034). (2) The results of scratch test and invasion test showed that the scratch healing rate and cell invasion rate of SKOV3 or CAOV3 cells treated with endothelin-1 (ET-1) and ET-1+ETAR-C were respectively compared, and the differences were statistically significant (all P<0.05). MTT assay showed that the inhibition rates of ETAR-C fusion polypeptide treated in SKOV3/cDDP and CAOV3/cDDP cells were significantly higher than those of control cells after the addition of 4, 6, 8, 10, 12, and 24 μg/ml cisplatin (all P<0.05). Western blot analysis showed that the relative expression levels of β-arrestin-1 in SKOV3 or CAOV3 cells treated with ET-1 and ET-1+ETAR-C were 1.85±0.09 and 1.13±0.09 (SKOV3 cells), 2.14±0.15 and 1.66±0.12 (CAOV3 cells), respectively. The differences were statistically significant (all P<0.05). Conclusions: The prognosis of HGSOC patients with high expression of ETAR mRNA is significantly worse than those with low expression of ETAR mRNA. ETAR might be a new target for HGSOC treatment. The ETAR-C fusion polypeptide that interferes with the interaction of ETAR and β-arrestin-1 has good inhibitory effect on ovarian cancer cells in vitro, and might have clinical application potential.
Female ; Humans ; Amino Acids/therapeutic use* ; beta-Arrestins/therapeutic use* ; Cell Line, Tumor ; Cisplatin/pharmacology* ; Clinical Relevance ; Ovarian Neoplasms/pathology* ; Receptor, Endothelin A/therapeutic use* ; RNA, Messenger/metabolism*

To analyze the association between exposure to air pollution and respiratory disease of primary school students in Chongqing City. Eight districts and counties were randomly selected based on the air pollution situation in Chongqing City. In each selected district and county, one primary school was randomly selected. A questionnaire survey was conducted on all primary school students in Grades 3-5 by the end of 2019. Air quality data from the nearest environmental monitoring sites were collected. A logistic regression model was used to analyze the impact of the living environment, lifestyle and air pollution on the respiratory disease of surveyed students. This study included 5 918 primary school students, with a prevalence rate of respiratory disease of 21.54%. The prevalence rates of boys and girls were 23.38% and 19.59%, respectively. The average Air quality index (AQI) of the surveyed school was 67, and the rates of exceeding standards of PM₁₀, PM_2.5, NO₂ and O₃ were 1.16%, 6.92%, 0.99% and 5.65%, respectively. The level of SO₂ and CO did not exceed the standard. After adjusting for relevant factors, logistic regression analysis showed that primary school students in areas with high exposure to air pollution (OR=2.52), using air pollution related-chemicals at home (OR=1.47), passive smoking (OR=1.27), and keeping pets at home (OR=1.18) had a higher risk of respiratory disease (all P<0.05). In addition, the average annual values of AQI (OR=1.18), PM₁₀ (OR=1.20), PM_2.5 (OR=1.35), and NO₂ (OR=1.11) increased the risk of respiratory diseases in primary school students (all P<0.05). In conclusion, the respiratory disease of primary school students in Chongqing City is related to the living environment, behavior habits and ambient air quality. The increased exposure concentration of PM₁₀, PM_2.5 and NO₂ in air pollutants can lead to an increased risk of respiratory disease among primary school students.
Female ; Humans ; Male ; Air Pollution/adverse effects* ; Nitrogen Dioxide ; Particulate Matter ; Respiratory Tract Diseases/epidemiology* ; Schools ; Students ; Child

Nitrogen dioxide (NO₂) is an important indoor air pollutant, with both outdoor and indoor sources contributing to indoor NO₂ exposure levels. Considering the association of high NO₂ exposure with adverse health effects, the Standards for indoor air quality (GB/T 18883-2022) have been revised to further restrict indoor NO₂ limit values. The 1-h average concentration limit value for NO₂ has been reduced from 0.24 mg/m³ to 200 μg/m³.This study analyzed the technical contents related to the determination of the limits of indoor NO₂ in Standards for Indoor Air Quality (GB/T 18883-2022), including source, exposure level, health effects, and the process and evidence basis for determining the limit value. It also proposed prospects for the direction for the implementation of the indoor NO₂ standard.
Humans ; Air Pollution, Indoor/adverse effects* ; Nitrogen Dioxide ; Air Pollutants/analysis* ; China ; Air Pollution/adverse effects*

In the central nervous system, nitric oxide (NO), a free gas with multitudinous bioactivities, is mainly produced from the oxidation of L-arginine by neuronal nitric oxide synthase (nNOS). In the past 20 years, the studies in our group and other laboratories have suggested a significant involvement of nNOS in a variety of neurological and neuropsychiatric disorders. In particular, the interactions between the PDZ domain of nNOS and its adaptor proteins, including post-synaptic density 95, the carboxy-terminal PDZ ligand of nNOS, and the serotonin transporter, significantly influence the subcellular localization and functions of nNOS in the brain. The nNOS-mediated protein-protein interactions provide new attractive targets and guide the discovery of therapeutic drugs for neurological and neuropsychiatric disorders. Here, we summarize the work on the roles of nNOS and its association with multiple adaptor proteins on neurological and neuropsychiatric disorders.
Humans ; Nitric Oxide Synthase Type I/metabolism* ; Adaptor Proteins, Signal Transducing ; Brain/metabolism* ; Nervous System Diseases

We reported the discovery of six novel coumarins, toddasirins A-F (1-6), each endowed with modified isoprenyl or geranyl side chains, derived from the roots of Toddalia asiatica. Comprehensive structural elucidation was achieved through multispectroscopic analyses, single-crystal X-ray diffraction experiments, and advanced quantum mechanical electronic circular dichroism (ECD) calculations. Furthermore, the anti-inflammatory activity of these compounds was assessed. Notably, compounds 1-3 and 6 demonstrated notable inhibitory effects on nitric oxide (NO) production in lipopolysaccharide (LPS)-induced RAW 264.7 cells, with 50% inhibitory concentration (IC₅₀) values of 3.22, 4.78, 8.90, and 4.31 μmol·L^-1, respectively.
Mice ; Animals ; Coumarins/chemistry* ; Rutaceae/chemistry* ; Anti-Inflammatory Agents/pharmacology* ; Plant Extracts/chemistry* ; RAW 264.7 Cells ; Nitric Oxide ; Molecular Structure

Five new racemic N-acetyldopamine (NADA) trimers, asponchimides A-E (1-5), were isolated from Aspongopus chinensis, a prominent traditional Chinese medicinal insect employed for alleviating pain, treating indigestion, and addressing kidney ailments. Compounds 1-5 were successfully resolved by chiral high-performance liquid chromatography (HPLC), yielding five pairs of enantiomers: (+)- and (-)-asponchimides A-E (1a/1b-5a/5b). Their structural identities were discerned by extensive spectroscopic analyses, including high-resolution mass spectrometry (HRMS), ultraviolet-visible (UV-Vis) spectroscopy, infrared (IR) spectroscopy, and nuclear magnetic resonance (NMR), and their absolute configurations were determined by electronic circular dichroism (ECD) calculations. Compounds 1-5 are pioneering instances of NADA trimers featuring a Δ⁷ double bond. When subjected to a series of bioassays, a majority of the compounds exhibited weak inhibitory activity against nitric oxide (NO) production in LPS-induced RAW 264.7 cells.
Molecular Structure ; Magnetic Resonance Spectroscopy ; Dopamine ; Nitric Oxide