1.Mechanism of Ferroptosis in Cerebral Ischemia-reperfusion and Interventional Mechanism of Huoxue Huayu Jiedu Prescription Based on "Blood Stasis and Toxin" Pathogenesis
Jiayue HAN ; Danyi PAN ; Jiaxuan XIAO ; Yuchen LIU ; Jiyong LIU ; Yidi ZENG ; Jinxia LI ; Caixing ZHENG ; Hua LI ; Wanghua LIU
Chinese Journal of Experimental Traditional Medical Formulae 2025;31(8):51-60
ObjectiveTo explore the material basis of the "interaction of blood stasis and toxin" mechanism in cerebral ischemia-reperfusion injury, as well as the protective role of Huoxue Huayu Jiedu prescription (HXHYJDF) against ferroptosis. MethodsSixty SPF-grade male SD rats were randomly divided into six groups: sham group, model group, deferoxamine (DFO) group (100 mg·kg-1), low-dose HXHYJDF group (4.52 g·kg-1), medium-dose HXHYJDF group (9.04 g·kg-1), and high-dose HXHYJDF group (18.07 g·kg-1), with ten rats in each group. Except for the sham group, the other groups were used to replicate the model of focal cerebral ischemia-reperfusion in the middle cerebral artery of rats by the reforming Longa method. Neurological function was assessed at 1st, 3rd, 5th, and 7th days post-reperfusion using the modified neurological severity scores (m-NSS). Brain tissue pathology and the morphology of mitochondria were observed using hematoxylin-eosin (HE) staining and transmission electron microscopy. The contents of malondialdehyde (MDA), glutathione (GSH), divalent iron ions (Fe2+), and reactive oxygen species (ROS) in the ischemic cerebral tissue were detected using enzyme-linked immunosorbent assay (ELISA). Immunohistochemistry and Western blot (WB) were used to detect the expression of iron death marker proteins glutathione peroxidase 4 (GPX4), ferroportin-1 (FPN1), transferrin receptor protein 1 (TfR1), and ferritin mitochondrial (FtMt) in brain tissue. ResultsCompared with the sham group, the mNSS score of the model group was significantly increased (P<0.01). HE staining showed that the number of neurons in the cortex of brain tissue was seriously reduced, and the intercellular space was widened. The nucleus was fragmented, and the cytoplasm was vacuolated. The results of transmission electron microscopy showed that the mitochondria in the cytoplasm contracted and rounded, and the mitochondrial cristae decreased. The matrix was lost and vacuolated, and the density of the mitochondrial bilayer membrane increased. The results of ELISA showed that the content of GSH decreased significantly (P<0.01), and the contents of MDA, Fe2+, and ROS increased significantly (P<0.01). The results of immunohistochemistry and WB showed that the expression of GPX4 and FPN1 proteins was significantly decreased (P<0.01), and the expression of FtMt and TfR1 proteins was significantly increased (P<0.01). Compared with those of the model group, the m-NSS scores of the high-dose and medium-dose HXHYJDF groups began to decrease on the 3rd and 5th days, respectively (P<0.05, P<0.01). The results of HE and transmission electron microscopy showed that the intervention of HXHYJDF improved the pathological changes of neurons and mitochondria. The results of ELISA showed that the content of GSH in the medium-dose and high-dose HXHYJDF groups increased significantly (P<0.01), and the contents of MDA, Fe2+, and ROS decreased significantly (P<0.05, P<0.01). The content of GSH in the low-dose HXHYJDF group increased significantly (P<0.01), and the contents of MDA and ROS decreased significantly (P<0.01). The results of immunohistochemistry showed that the expression of GPX4 and FPN1 in the high-dose HXHYJDF group increased significantly (P<0.01), and the expression of FtMt and TfR1 decreased significantly (P<0.01). The expression of GPX4 and FPN1 in the medium-dose HXHYJDF group increased significantly (P<0.05), and the expression of TfR1 decreased significantly (P<0.01). WB results showed that the expression levels of FPN1 and GPX4 proteins in the high-dose, medium-dose, and low-dose HXHYJDF groups were significantly up-regulated (P<0.01), and the expression levels of FtMt and TfR1 proteins were significantly down-regulated (P<0.01). ConclusionHXHYJDF can significantly improve neurological dysfunction symptoms in rats with cerebral ischemia-reperfusion injury, improve the pathological morphology of the infarcted brain tissue, and protect the brain tissue of rats with cerebral ischemia-reperfusion injury to a certain extent. Neuronal ferroptosis is involved in cerebral ischemia-reperfusion injury, with increased levels of MDA, Fe2+, ROS, and TfR1 and decreased levels of FtMt, FPN1, GPX4, and GSH potentially constituting the material basis of the interaction of blood stasis and toxin mechanism in cerebral ischemia-reperfusion injury. HXHYJDF may exert brain-protective effects by regulating iron metabolism-related proteins, promoting the discharge of free iron, reducing brain iron deposition, alleviating oxidative stress, and inhibiting ferroptosis.
2.Mechanism of Pizhan Powder in regulating the Wnt4/β-catenin signaling pathway to promote wound healing in mice with chronic skin ulcers
Pingxinyi QUE ; Xiang XIAO ; Li ZENG ; Xianbin ZHAO ; Min XIAO ; Songqi TANG
Journal of Beijing University of Traditional Chinese Medicine 2025;48(2):205-215
Objective:
We aimed to explore the mechanism of Pizhan Powder in regulating the Wnt4/β-catenin signaling pathway to promote wound healing in mice with chronic skin ulcer.
Methods:
Male BALB/c mice were divided into blank, model, Pizhan Powder, Pizhan powder removed bark medications, bark medications, inhibitor, and Pizhan Powder + inhibitor groups using the random number table method, with six mice per group. Except for the blank group, chronic skin ulcer wound models were prepared in the other groups by implanting foreign bodies. The blank control group received no treatment, whereas the wounds of the model group were cleaned with furacilin solution. The Pizhan Powder, Pizhan Powder removed bark medications, and bark medications groups were each administered 0.1 g of the corresponding medication on the skin wounds. The inhibitor group received an intraperitoneal injection of 3-(4-methylphenylsulfonamido) benzoic acid methyl ester (MSAB) at a dosage of 10 mg/kg. The Pizhan Powder + inhibitor group was administered 0.1 g of Pizhan Powder on the skin wound, and an intraperitoneal injection of MSAB was also administered (10 mg/kg). These treatments were administered once a day for 14 consecutive days. Wound healing was observed on the first, third, seventh, and 14th day of treatment; hematoxylin and eosin staining was used to observe the pathological changes of ulcerated skin; keratin 10 (CK10), keratin 14 (CK14), cell proliferation nuclear antigen (Ki-67), α-smooth muscle actin (α-SMA), and β-catenin expression in wounds was observed through immunofluorescence; Western blotting was used to detect the expression of signaling pathway-related proteins (Wnt4 and β-catenin).
Results:
Compared to the model group, the Pizhan Powder group showed a reduced wound area and an increased wound healing rate (P<0.05) and elevated CK10, CK14, Ki-67, α-SMA, β-catenin, and Wnt4 protein expressions (P<0.05). Compared to the Pizhan Powder group, the wound healing rate of the bark medications and Pizhan Powder removed bark medications groups was reduced (P<0.05). The wound healing rate and the fluorescence expression of CK10, CK14, Ki-67, and α-SMA in the Pizhan Powder removed bark medications group were lower than that in the bark medications group (P<0.05). Compared to the Pizhan Powder group, the wound healing rate of the Pizhan Powder + inhibitor group was reduced, and CK10, CK14, Ki-67, α-SMA, β-catenin and Wnt4 protein expression were lower (P<0.05).
Conclusion
Pizhan Powder promotes wound healing in chronic skin ulcers of mice by regulating the Wnt4/β-catenin signaling pathway. The bark medications (buffalo hide, white mulberry root-bark, and Chinese wolfberry root-bark) play a crucial role, representing a concrete application of the traditional Chinese medicine theory of " treating skin with skin.
3.Progress on antisense oligonucleotide in the field of antibacterial therapy
Jia LI ; Xiao-lu HAN ; Shi-yu SONG ; Jin-tao LIN ; Zhi-qiang TANG ; Zeng-ming WANG ; Liang XU ; Ai-ping ZHENG
Acta Pharmaceutica Sinica 2025;60(2):337-347
With the widespread use of antibiotics, drug-resistant bacterial infections have become a significant threat to human health. Finding new antibacterial strategies that can effectively control drug-resistant bacterial infections has become an urgent task. Unlike small molecule drugs that target bacterial proteins, antisense oligonucleotide (ASO) can target genes related to bacterial resistance, pathogenesis, growth, reproduction and biofilm formation. By regulating the expression of these genes, ASO can inhibit or kill bacteria, providing a novel approach for the development of antibacterial drugs. To overcome the challenge of delivering antisense oligonucleotide into bacterial cells, various drug delivery systems have been applied in this field, including cell-penetrating peptides, lipid nanoparticles and inorganic nanoparticles, which have injected new momentum into the development of antisense oligonucleotide in the antibacterial realm. This review summarizes the current development of small nucleic acid drugs, the antibacterial mechanisms, targets, sequences and delivery vectors of antisense oligonucleotide, providing a reference for the research and development of antisense oligonucleotide in the treatment of bacterial infections.
4.Mechanism of Euphorbiae Ebracteolatae Radix processed by milk in reducing intestinal toxicity.
Chang-Li SHEN ; Hao WU ; Hong-Li YU ; Hong-Mei WEN ; Xiao-Bing CUI ; Hui-Min BIAN ; Tong-la-Ga LI ; Min ZENG ; Yan-Qing XU ; Yu-Xin GU
China Journal of Chinese Materia Medica 2025;50(12):3204-3213
This study aimed to investigate the correlation between changes in intestinal toxicity and compositional alterations of Euphorbiae Ebracteolatae Radix(commonly known as Langdu) before and after milk processing, and to explore the detoxification mechanism of milk processing. Mice were intragastrically administered the 95% ethanol extract of raw Euphorbiae Ebracteolatae Radix, milk-decocted(milk-processed), and water-decocted(water-processed) Euphorbiae Ebracteolatae Radix. Fecal morphology, fecal water content, and the release levels of inflammatory cytokines tumor necrosis factor-α(TNF-α) and interleukin-1β(IL-1β) in different intestinal segments were used as indicators to evaluate the effects of different processing methods on the cathartic effect and intestinal inflammatory toxicity of Euphorbiae Ebracteolatae Radix. LC-MS/MS was employed to analyze the small-molecule components in the raw product, the 95% ethanol extract of the milk-processed product, and the milky waste(precipitate) formed during milk processing, to assess the impact of milk processing on the chemical composition of Euphorbiae Ebracteolatae Radix. The results showed that compared with the blank group, both the raw and water-processed Euphorbiae Ebracteolatae Radix significantly increased the fecal morphology score, fecal water content, and the release levels of TNF-α and IL-1β in various intestinal segments(P<0.05). Compared with the raw group, all indicators in the milk-processed group significantly decreased(P<0.05), while no significant differences were observed in the water-processed group, indicating that milk, as an adjuvant in processing, plays a key role in reducing the intestinal toxicity of Euphorbiae Ebracteolatae Radix. Mass spectrometry results revealed that 29 components were identified in the raw product, including 28 terpenoids and 1 acetophenone. The content of these components decreased to varying extents after milk processing. A total of 28 components derived from Euphorbiae Ebracteolatae Radix were identified in the milky precipitate, of which 27 were terpenoids, suggesting that milk processing promotes the transfer of toxic components from Euphorbiae Ebracteolatae Radix into milk. To further investigate the effect of milk adjuvant processing on the toxic terpenoid components of Euphorbiae Ebracteolatae Radix, transmission electron microscopy(TEM) was used to observe the morphology of self-assembled casein micelles(the main protein in milk) in the milky precipitate. The micelles formed in casein-terpenoid solutions were characterized using particle size analysis, fluorescence spectroscopy, ultraviolet spectroscopy, and Fourier-transform infrared(FTIR) spectroscopy. TEM observations confirmed the presence of casein micelles in the milky precipitate. Characterization results showed that with increasing concentrations of toxic terpenoids, the average particle size of casein micelles increased, fluorescence intensity of the solution decreased, the maximum absorption wavelength in the UV spectrum shifted, and significant changes occurred in the infrared spectrum, indicating that interactions occurred between casein micelles and toxic terpenoid components. These findings indicate that the cathartic effect of Euphorbiae Ebracteolatae Radix becomes milder and its intestinal inflammatory toxicity is reduced after milk processing. The detoxification mechanism is that terpenoid components in Euphorbiae Ebracteolatae Radix reassemble with casein in milk to form micelles, promoting the transfer of some terpenoids into the milky precipitate.
Animals
;
Mice
;
Milk/chemistry*
;
Drugs, Chinese Herbal/chemistry*
;
Male
;
Tumor Necrosis Factor-alpha/immunology*
;
Intestines/drug effects*
;
Interleukin-1beta/immunology*
;
Tandem Mass Spectrometry
;
Female
5.Study on protective effect of arbutin in yam on acute lung injury and its metabolic regulation mechanism.
Kai-Li YE ; Meng-Nan ZENG ; Feng-Xiao HAO ; Peng-Li GUO ; Yu-Han ZHANG ; Wei-Sheng FENG ; Xiao-Ke ZHENG
China Journal of Chinese Materia Medica 2025;50(15):4100-4109
This study investigated the protective effect of arbutin(Arb) in yam on lipopolysaccharide(LPS)-induced acute lung injury(ALI) in a mouse model and revealed its possible mechanism of action by metabolomics technology, providing a theoretical basis for clinical treatment of ALI. SPF BALB/c mice were randomly divided into normal control group, model group, resveratrol(Rv)-positive control group, Arb low-dose(15 mg·kg~(-1)) group, and Arb high-dose(30 mg·kg~(-1)) group. The LPS-induced ALI model was established in all groups except the normal control group. Hematoxylin-eosin(HE) staining, TUNEL staining, and WBP whole-body non-invasive pulmonary function testing were used to evaluate the degree of lung tissue damage and lung function changes. Enzyme-linked immunosorbent assay(ELISA) was used to detect the level of inflammatory factors in lung tissue. Flow cytometry was used to analyze the M1/M2 polarization status of macrophages in lung tissue. Western blot was used to detect the expression levels of the TLR4 signaling pathway and related apoptotic proteins. Liquid chromatograph-mass spectrometer(LC-MS) metabolomics was used to analyze the changes in serum metabolic profile after Arb intervention. The results showed that Arb pretreatment significantly alleviated LPS-induced lung tissue injury, improved lung function, reduced the levels of pro-inflammatory factors(IL-6, TNF-α, IL-18, and IL-1β), and regulated the polarization status of M1/M2 macrophages. In addition, Arb inhibited the activation of the TLR4 signaling pathway, reduced the expression of pro-apoptotic proteins such as Bax, caspase-3, and caspase-9, up-regulated the level of Bcl-2 protein, and inhibited apoptosis of lung cells. Metabolomic analysis showed that Arb significantly improved LPS-induced metabolic abnormalities, mainly involving key pathways such as galactose metabolism, phenylalanine metabolism, and lipid metabolism. In summary, Arb can significantly reduce LPS-induced ALI by regulating the release of inflammatory factors, inhibiting the activation of the TLR4 signaling pathway, improving metabolic disorders, and regulating macrophage polarization, indicating that Arb has potential clinical application value.
Animals
;
Acute Lung Injury/chemically induced*
;
Mice
;
Mice, Inbred BALB C
;
Arbutin/administration & dosage*
;
Male
;
Toll-Like Receptor 4/immunology*
;
Apoptosis/drug effects*
;
Lung/metabolism*
;
Signal Transduction/drug effects*
;
Protective Agents/administration & dosage*
;
Humans
;
Macrophages/immunology*
;
Drugs, Chinese Herbal/administration & dosage*
6.Discovery of orally active and serine-targeting covalent inhibitors against hCES2A for ameliorating irinotecan-triggered gut toxicity.
Ya ZHANG ; Yufan FAN ; Yunqing SONG ; Guanghao ZHU ; Xinjuan LI ; Jian HUANG ; Xinrui GUO ; Changhai LUAN ; Dongning KANG ; Lu CHEN ; Zhangping XIAO ; Zhaobin GUO ; Hairong ZENG ; Dapeng CHEN ; Zhipei SANG ; Guangbo GE
Acta Pharmaceutica Sinica B 2025;15(10):5312-5326
Human carboxylesterase 2A (hCES2A) plays pivotal roles in prodrug activation and hydrolytic metabolism of ester-bearing chemicals. Targeted inhibition of intestinal hCES2A represents a feasible strategy to mitigate irinotecan-triggered gut toxicity (ITGT), but the orally active, selective, and efficacious hCES2A inhibitors are rarely reported. Here, a novel drug-like hCES2A inhibitor was developed via three rounds of structure-based drug design (SBDD) and structural optimization. Initially, donepezil was identified as a moderate hCES2A inhibitor from 2000 US Food and Drug Administration (FDA)-approved drugs. Following two rounds of SBDD and structural optimization, a donepezil derivative (B7) was identified as a strong reversible hCES2A inhibitor. Subsequently, nine B7 carbamates were rationally designed, synthesized and biologically assayed. Among all synthesized carbamates, C3 showed the most potent time-dependent inhibition on hCES2A (IC50 = 0.56 nmol/L), excellent specificity and favorable drug-like properties. C3 could covalently modify the catalytic serine of hCES2A with high selectivity, while this agent also showed favorable safety profiles, high intestinal exposure, and impressive effects for ameliorating ITGT in both human intestinal organoids and tumor-bearing mice. Collectively, this study showcases a rational strategy for developing drug-like and serine-targeting covalent inhibitors against target serine hydrolase(s), while C3 emerges as a promising orally active drug candidate for ameliorating ITGT.
7.Trends in Metabolically Unhealthy Obesity by Age, Sex, Race/Ethnicity, and Income among United States Adults, 1999 to 2018
Wen ZENG ; Weijiao ZHOU ; Junlan PU ; Juan LI ; Xiao HU ; Yuanrong YAO ; Shaomei SHANG
Diabetes & Metabolism Journal 2025;49(3):475-484
Background:
This study aimed to estimate temporal trends in metabolically unhealthy obesity (MUO) among United States (US) adults by age, sex, race/ethnicity, and income from 1999 to 2018.
Methods:
We included 17,230 non-pregnant adults from a nationally representative cross-sectional study, the National Health and Nutrition Examination Survey (NHANES). MUO was defined as body mass index ≥30 kg/m2 with any metabolic disorders in blood pressure, blood glucose, and blood lipids. The age-adjusted percentage of MUO was calculated, and linear regression models estimated trends in MUO.
Results:
The weighted mean age of adults was 47.28 years; 51.02% were male, 74.64% were non-Hispanic White. The age-adjusted percentage of MUO continuously increased in adults across all subgroups during 1999–2018, although with different magnitudes (all P<0.05 for linear trend). Adults aged 45 to 64 years consistently had higher percentages of MUO from 1999–2000 (34.25%; 95% confidence interval [CI], 25.85% to 42.66%) to 2017–2018 (42.03%; 95% CI, 35.09% to 48.97%) than the other two age subgroups (P<0.05 for group differences). The age-adjusted percentage of MUO was the highest among non-Hispanic Blacks while the lowest among non-Hispanic Whites in most cycles. Adults with high-income levels generally had lower MUO percentages from 1999–2000 (22.63%; 95% CI, 17.00% to 28.26%) to 2017–2018 (32.36%; 95% CI, 23.87% to 40.85%) compared with the other two subgroups.
Conclusion
This study detected a continuous linear increasing trend in MUO among US adults from 1999 to 2018. The persistence of disparities by age, race/ethnicity, and income is a cause for concern. This calls for implementing evidence-based, structural, and effective MUO prevention programs.
8.Trends in Metabolically Unhealthy Obesity by Age, Sex, Race/Ethnicity, and Income among United States Adults, 1999 to 2018
Wen ZENG ; Weijiao ZHOU ; Junlan PU ; Juan LI ; Xiao HU ; Yuanrong YAO ; Shaomei SHANG
Diabetes & Metabolism Journal 2025;49(3):475-484
Background:
This study aimed to estimate temporal trends in metabolically unhealthy obesity (MUO) among United States (US) adults by age, sex, race/ethnicity, and income from 1999 to 2018.
Methods:
We included 17,230 non-pregnant adults from a nationally representative cross-sectional study, the National Health and Nutrition Examination Survey (NHANES). MUO was defined as body mass index ≥30 kg/m2 with any metabolic disorders in blood pressure, blood glucose, and blood lipids. The age-adjusted percentage of MUO was calculated, and linear regression models estimated trends in MUO.
Results:
The weighted mean age of adults was 47.28 years; 51.02% were male, 74.64% were non-Hispanic White. The age-adjusted percentage of MUO continuously increased in adults across all subgroups during 1999–2018, although with different magnitudes (all P<0.05 for linear trend). Adults aged 45 to 64 years consistently had higher percentages of MUO from 1999–2000 (34.25%; 95% confidence interval [CI], 25.85% to 42.66%) to 2017–2018 (42.03%; 95% CI, 35.09% to 48.97%) than the other two age subgroups (P<0.05 for group differences). The age-adjusted percentage of MUO was the highest among non-Hispanic Blacks while the lowest among non-Hispanic Whites in most cycles. Adults with high-income levels generally had lower MUO percentages from 1999–2000 (22.63%; 95% CI, 17.00% to 28.26%) to 2017–2018 (32.36%; 95% CI, 23.87% to 40.85%) compared with the other two subgroups.
Conclusion
This study detected a continuous linear increasing trend in MUO among US adults from 1999 to 2018. The persistence of disparities by age, race/ethnicity, and income is a cause for concern. This calls for implementing evidence-based, structural, and effective MUO prevention programs.
9.Trends in Metabolically Unhealthy Obesity by Age, Sex, Race/Ethnicity, and Income among United States Adults, 1999 to 2018
Wen ZENG ; Weijiao ZHOU ; Junlan PU ; Juan LI ; Xiao HU ; Yuanrong YAO ; Shaomei SHANG
Diabetes & Metabolism Journal 2025;49(3):475-484
Background:
This study aimed to estimate temporal trends in metabolically unhealthy obesity (MUO) among United States (US) adults by age, sex, race/ethnicity, and income from 1999 to 2018.
Methods:
We included 17,230 non-pregnant adults from a nationally representative cross-sectional study, the National Health and Nutrition Examination Survey (NHANES). MUO was defined as body mass index ≥30 kg/m2 with any metabolic disorders in blood pressure, blood glucose, and blood lipids. The age-adjusted percentage of MUO was calculated, and linear regression models estimated trends in MUO.
Results:
The weighted mean age of adults was 47.28 years; 51.02% were male, 74.64% were non-Hispanic White. The age-adjusted percentage of MUO continuously increased in adults across all subgroups during 1999–2018, although with different magnitudes (all P<0.05 for linear trend). Adults aged 45 to 64 years consistently had higher percentages of MUO from 1999–2000 (34.25%; 95% confidence interval [CI], 25.85% to 42.66%) to 2017–2018 (42.03%; 95% CI, 35.09% to 48.97%) than the other two age subgroups (P<0.05 for group differences). The age-adjusted percentage of MUO was the highest among non-Hispanic Blacks while the lowest among non-Hispanic Whites in most cycles. Adults with high-income levels generally had lower MUO percentages from 1999–2000 (22.63%; 95% CI, 17.00% to 28.26%) to 2017–2018 (32.36%; 95% CI, 23.87% to 40.85%) compared with the other two subgroups.
Conclusion
This study detected a continuous linear increasing trend in MUO among US adults from 1999 to 2018. The persistence of disparities by age, race/ethnicity, and income is a cause for concern. This calls for implementing evidence-based, structural, and effective MUO prevention programs.
10.Trends in Metabolically Unhealthy Obesity by Age, Sex, Race/Ethnicity, and Income among United States Adults, 1999 to 2018
Wen ZENG ; Weijiao ZHOU ; Junlan PU ; Juan LI ; Xiao HU ; Yuanrong YAO ; Shaomei SHANG
Diabetes & Metabolism Journal 2025;49(3):475-484
Background:
This study aimed to estimate temporal trends in metabolically unhealthy obesity (MUO) among United States (US) adults by age, sex, race/ethnicity, and income from 1999 to 2018.
Methods:
We included 17,230 non-pregnant adults from a nationally representative cross-sectional study, the National Health and Nutrition Examination Survey (NHANES). MUO was defined as body mass index ≥30 kg/m2 with any metabolic disorders in blood pressure, blood glucose, and blood lipids. The age-adjusted percentage of MUO was calculated, and linear regression models estimated trends in MUO.
Results:
The weighted mean age of adults was 47.28 years; 51.02% were male, 74.64% were non-Hispanic White. The age-adjusted percentage of MUO continuously increased in adults across all subgroups during 1999–2018, although with different magnitudes (all P<0.05 for linear trend). Adults aged 45 to 64 years consistently had higher percentages of MUO from 1999–2000 (34.25%; 95% confidence interval [CI], 25.85% to 42.66%) to 2017–2018 (42.03%; 95% CI, 35.09% to 48.97%) than the other two age subgroups (P<0.05 for group differences). The age-adjusted percentage of MUO was the highest among non-Hispanic Blacks while the lowest among non-Hispanic Whites in most cycles. Adults with high-income levels generally had lower MUO percentages from 1999–2000 (22.63%; 95% CI, 17.00% to 28.26%) to 2017–2018 (32.36%; 95% CI, 23.87% to 40.85%) compared with the other two subgroups.
Conclusion
This study detected a continuous linear increasing trend in MUO among US adults from 1999 to 2018. The persistence of disparities by age, race/ethnicity, and income is a cause for concern. This calls for implementing evidence-based, structural, and effective MUO prevention programs.


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