Oxysterol Sensing Through GPR183 Triggers Endothelial Senescence in Hypertension.

BACKGROUND: Despite endothelial dysfunction being an initial step in the development of hypertension and associated cardiovascular/renal injuries, effective therapeutic strategies to prevent endothelial dysfunction are still lacking. GPR183 (G protein-coupled receptor 183), a recently identified G protein-coupled receptor for oxysterols and hydroxylated metabolites of cholesterol, has pleiotropic roles in lipid metabolism and immune responses. However, the role of GPR183 in the regulation of endothelial function remains unknown. METHODS: Endothelial-specific GPR183 knockout mice were generated and used to examine the role of GPR183 in endothelial senescence by establishing 2 independent hypertension models: desoxycorticosterone acetate/salt-induced and Ang II (angiotensin II)-induced hypertensive mice. Echocardiography, transmission electron microscopy, blood pressure measurement, vasorelaxation response experiments, flow cytometry analysis, and chromatin immunoprecipitation analysis were performed in this study. RESULTS: Endothelial GPR183 was significantly induced in hypertensive mice, which was further confirmed in renal biopsies from subjects with hypertensive nephropathy. Endothelial-specific deficiency of GPR183 markedly alleviated cardiovascular and renal injuries in hypertensive mice. Moreover, we found that GPR183 regulated endothelial senescence in both hypertensive mice and aged mice. Mechanistically, GPR183 disrupted circadian signaling by inhibiting PER1 (period 1) expression, thereby facilitating endothelial senescence and dysfunction through the cAMP/PKA (protein kinase A)/CREB (cAMP-response element binding protein) signaling pathway. Importantly, pharmacological inhibition of the oxysterol-GPR183 axis by NIBR189 or clotrimazole ameliorated endothelial senescence and cardiovascular/renal injuries in hypertensive mice. CONCLUSIONS: This study discovers a previously unrecognized role of GPR183 in promoting endothelial senescence. Pharmacological targeting of GPR183 may be an innovative therapeutic strategy for hypertension and its associated complications.

Assessing the causal relationship between plasma proteins and osteoporosis: novel insights into pathological mechanisms and therapeutic implications.

Identifying dysregulated plasma proteins in osteoporosis (OP) progression offers insights into prevention and treatment. This study found 8 such proteins associated with OP, suggesting them as therapy targets. This discovery may cut drug development costs and improve personalized treatments. PURPOSE: This study aims to identify potential therapeutic targets for OP using summary data-based Mendelian randomization (SMR) and colocalization analysis methods. Furthermore, we seek to explore the biological significance and pharmacological value of these drug targets. METHODS: To identify potential therapeutic targets for OP, we conducted SMR and colocalization analysis. Plasma protein (pQTL, exposure) data were sourced from the study by Ferkingstad et al. (n = 35,559). Summary statistics for bone mineral density (BMD, outcome) were obtained from the GWAS Catalog (n = 56,284). Additionally, we utilized enrichment analysis, protein-protein interaction (PPI) network analysis, drug prediction, and molecular docking to further analyze the biological significance and pharmacological value of these drug targets. RESULTS: In the SMR analysis, while 20 proteins showed significance, only 8 potential drug targets (GCKR, ERBB3, CFHR1, GPN1, SDF2, VTN, BET1L, and SERPING1) received support from colocalization (PP.H4 > 0.8). These proteins are closely associated with immune function in terms of biological significance. Molecular docking also demonstrated favorable binding of drugs to proteins, consistent with existing structural data, further substantiating the pharmacological value of these targets. CONCLUSIONS: The study identified 8 potential drug targets for OP. These prospective targets are believed to have a higher chance of success in clinical trials, thus aiding in prioritizing OP drug development and reducing development costs.

Porous Silicon Carbide (SiC): A Chance for Improving Catalysts or Just Another Active-Phase Carrier?

There is an obvious gap between efforts dedicated to the control of chemicophysical and morphological properties of catalyst active phases and the attention paid to the search of new materials to be employed as functional carriers in the upgrading of heterogeneous catalysts. Economic constraints and common habits in preparing heterogeneous catalysts have narrowed the selection of active-phase carriers to a handful of materials: oxide-based ceramics (e.g. Al2O3, SiO2, TiO2, and aluminosilicates-zeolites) and carbon. However, these carriers occasionally face chemicophysical constraints that limit their application in catalysis. For instance, oxides are easily corroded by acids or bases, and carbon is not resistant to oxidation. Therefore, these carriers cannot be recycled. Moreover, the poor thermal conductivity of metal oxide carriers often translates into permanent alterations of the catalyst active sites (i.e. metal active-phase sintering) that compromise the catalyst performance and its lifetime on run. Therefore, the development of new carriers for the design and synthesis of advanced functional catalytic materials and processes is an urgent priority for the heterogeneous catalysis of the future. Silicon carbide (SiC) is a non-oxide semiconductor with unique chemicophysical properties that make it highly attractive in several branches of catalysis. Accordingly, the past decade has witnessed a large increase of reports dedicated to the design of SiC-based catalysts, also in light of a steadily growing portfolio of porous SiC materials covering a wide range of well-controlled pore structure and surface properties. This review article provides a comprehensive overview on the synthesis and use of macro/mesoporous SiC materials in catalysis, stressing their unique features for the design of efficient, cost-effective, and easy to scale-up heterogeneous catalysts, outlining their success where other and more classical oxide-based supports failed. All applications of SiC in catalysis will be reviewed from the perspective of a given chemical reaction, highlighting all improvements rising from the use of SiC in terms of activity, selectivity, and process sustainability. We feel that the experienced viewpoint of SiC-based catalyst producers and end users (these authors) and their critical presentation of a comprehensive overview on the applications of SiC in catalysis will help the readership to create its own opinion on the central role of SiC for the future of heterogeneous catalysis.

Epitaxial Cubic Silicon Carbide Photocathodes for Visible-Light-Driven Water Splitting.

Cubic silicon carbide (3C-SiC) material feature a suitable bandgap and high resistance to photocorrosion. Thus, it has been emerged as a promising semiconductor for hydrogen evolution. Here, the relationship between the photoelectrochemical properties and the microstructures of different SiC materials is demonstrated. For visible-light-derived water splitting to hydrogen production, nanocrystalline, microcrystalline and epitaxial (001) 3C-SiC films are applied as the photocathodes. The epitaxial 3C-SiC film presents the highest photoelectrochemical activity for hydrogen evolution, because of its perfect (001) orientation, high phase purity, low resistance, and negative conduction band energy level. This finding offers a strategy to design SiC-based photocathodes with superior photoelectrochemical performances.

LncRNA STARD13-AS blocks lung squamous carcinoma cells growth and movement by targeting miR-1248/C3A.

BACKGROUND: This research aims to illustrate the effect of lncRNA StAR Related Lipid Transfer Domain Containing 13 antisense RN (STARD13-AS)/miR-1248/C3A on lung squamous carcinoma cells growth and metastasis. METHODS: Bioinformatics analysis was applied to detect the expression of STARD13-AS/miR-1248/C3A in lung cancer samples and establish the ceRNA network. Transfection was performed to construct over-expression or knockdown models. PCR was implemented to examine the transfection efficiency. The biological function including growth, invasion and migration of LUSC cells were estimated by CCK-8 analysis, colony formation assay and transwell assay. Luciferase assay was executed to analyze the relationship between C3A and miR-1248, as well as miR-1248 and STARD13-AS. RESULTS: By consulting the TCGA database and GEPIA website, we found that C3A expression was significantly reduced in LUSC samples. Additionally, we also discovered that miR-1248, which was a downstream target of STARD13-AS, was presented as an upstream regulator of C3A. Moreover, STARD13-AS was under expressed in LUSC cells and has a negative effect on LUSC cells growth ability. C3A expression was co-regulated by miR-1248 and STARD13-AS. Importantly, the inhibitory effect of C3A or the promoting effect of miR-1248 on LUSC cells growth, invasion and migration abilities can be regulated by STARD13-AS. CONCLUSIONS: Our findings revealed that overexpression of STARD13-AS restricted the growth and aggressiveness of LUSC cells via regulating miR-1248/C3A.

Atomic Carbon Layers Supported Pt Nanoparticles for Minimized CO Poisoning and Maximized Methanol Oxidation.

Maximizing activity of Pt catalysts toward methanol oxidation reaction (MOR) together with minimized poisoning of adsorbed CO during MOR still remains a big challenge. In the present work, uniform and well-distributed Pt nanoparticles (NPs) grown on an atomic carbon layer, that is in situ formed by means of dry-etching of silicon carbide nanoparticles (SiC NPs) with CCl4 gas, are explored as potential catalysts for MOR. Significantly, as-synthesized catalysts exhibit remarkably higher MOR catalytic activity (e.g., 647.63 mA mg-1 at a peak potential of 0.85 V vs RHE) and much improved anti-CO poisoning ability than the commercial Pt/C catalysts, Pt/carbon nanotubes, and Pt/graphene catalysts. Moreover, the amount of expensive Pt is a few times lower than that of the commercial and reported catalyst systems. As confirmed from density functional theory (DFT) calculations and X-ray absorption fine structure (XAFS) measurements, such high performance is due to reduced adsorption energy of CO on the Pt NPs and an increased amount of adsorbed energy OH species that remove adsorbed CO fast and efficiently. Therefore, these catalysts can be utilized for the development of large-scale and industry-orientated direct methanol fuel cells.

Visible-Light-Driven Selective Photocatalytic Hydrogenation of Cinnamaldehyde over Au/SiC Catalysts.

Highly selective hydrogenation of cinnamaldehyde to cinnamyl alcohol with 2-propanol was achieved using SiC-supported Au nanoparticles as photocatalyst. The hydrogenation reached a turnover frequency as high as 487 h(-1) with 100% selectivity for the production of alcohol under visible light irradiation at 20 °C. This high performance is attributed to a synergistic effect of localized surface plasmon resonance of Au NPs and charge transfer across the SiC/Au interface. The charged metal surface facilitates the oxidation of 2-propanol to form acetone, while the electron and steric effects at the interface favor the preferred end-adsorption of α,ß-unsaturated aldehydes for their selective conversion to unsaturated alcohols. We show that this Au/SiC photocatalyst is capable of hydrogenating a large variety of α,ß-unsaturated aldehydes to their corresponding unsaturated alcohols with high conversion and selectivity.

Copper nanoparticles on graphene support: an efficient photocatalyst for coupling of nitroaromatics in visible light.

Copper is a low-cost plasmonic metal. Efficient photocatalysts of copper nanoparticles on graphene support are successfully developed for controllably catalyzing the coupling reactions of aromatic nitro compounds to the corresponding azoxy or azo compounds under visible-light irradiation. The coupling of nitrobenzene produces azoxybenzene with a yield of 90 % at 60 °C, but azobenzene with a yield of 96 % at 90 °C. When irradiated with natural sunlight (mean light intensity of 0.044 W cm(-2) ) at about 35 °C, 70 % of the nitrobenzene is converted and 57 % of the product is azobenzene. The electrons of the copper nanoparticles gain the energy of the incident light through a localized surface plasmon resonance effect and photoexcitation of the bound electrons. The excited energetic electrons at the surface of the copper nanoparticles facilitate the cleavage of the NO bonds in the aromatic nitro compounds. Hence, the catalyzed coupling reaction can proceed under light irradiation and moderate conditions. This study provides a green photocatalytic route for the production of azo compounds and highlights a potential application for graphene.

Multi-scale bioimpedance flexible sensing with causal hierarchical machine learning for fish vitality evaluation under adversity stress.

It is expected that waterless low-temperature stressful environments will induce stress responses in fish and affect their vitality. In this study, we developed a laser-activated, stretchable, highly conductive liquid metal (LM) based flexible sensor system for fish multi-scale bioimpedance detection. It has excellent conformability, electrical conductivity, bending and cyclic tensile stability. Meanwhile, test result showed that wireless power supply is a potential solution for realizing safe power supply for devices inside waterless low-temperature packages. In addition, a hierarchical regression model (GC-HRM) based on Granger causality was established. The result showed that tissue bioimpedance can induce changes in individual bioimpedance with unidirectional Granger causality. The R2 of the linear regression (LR), support vector regression (SVR) and artificial neural network (ANN) models under single-scale individual bioimpedance were 0.85, 0.90 and 0.78, respectively. By adding the multi-scale bioimpedance features, the R2 of the LR, SVR and ANN models were improved to 0.95, 1.00 and 0.98, respectively.

The Role of Traditional Chinese Medicines in the Treatment of Osteoporosis.

Osteoporosis (OP) represents a substantial public health issue and is associated with increasing rates of morbidity and mortality. It is characterized by reduced bone mineral density, deterioration of bone tissue quality, disruption of the microarchitecture of bones, and compromised bone strength. These changes may be attributed to the following factors: intercellular communication between osteoblasts and osteoclasts; imbalanced bone remodeling; imbalances between osteogenesis and adipogenesis; imbalances in hormonal regulation; angiogenesis; chronic inflammation; oxidative stress; and intestinal microbiota imbalances. Treating a single aspect of the disease is insufficient to address its multifaceted nature. In recent decades, traditional Chinese medicine (TCM) has shown great potential in the treatment of OP, and the therapeutic effects of Chinese patent drugs and Chinese medicinal herbs have been scientifically proven. TCMs, which contain multiple components, can target the diverse pathogeneses of OP through a multitargeted approach. Herbs such as XLGB, JTG, GSB, Yinyanghuo, Gusuibu, Buguzhi, and Nvzhenzi are among the TCMs that can be used to treat OP and have demonstrated promising effects in this context. They exert their therapeutic effects by targeting various pathways involved in bone metabolism. These TCMs balance the activity of osteoblasts (bone-forming cells) and osteoclasts (bone-resorbing cells), and they exhibit anti-inflammatory, immunomodulatory, anti-oxidative, and estrogen-like functions. These multifaceted mechanisms underlie the efficacy of these herbs in the management and treatment of OP. Herein, we examine the efficacy of various Chinese herbs and Chinese patent drugs in treating OP by reviewing previous clinical trials and basic experiments, and we examine the potential mechanism of these therapies to provide evidence regarding the use of TCM for treating OP.

Osteoporosis and depression in perimenopausal women: From clinical association to genetic causality.

BACKGROUND: Osteoporosis and major depressive disorder (MDD) represent two significant health challenges globally, particularly among perimenopausal women. This study utilizes NHANES data and Mendelian randomization (MR) analysis to explore the link between them, aiming to provide a basis for intervention strategies for this group. METHODS: The study analyzed NHANES 2007-2018 data using weighted logistic regression in R software to evaluate the link between MDD and osteoporosis risk. Then, a two-sample MR analysis with GWAS summary statistics was performed, mainly using the IVW method. Additional validation included MR Egger, Weighted Median, Mode, and MR-PRESSO methods. RESULTS: The research analysis indicated a significant link between MDD and the risk of osteopenia/osteoporosis. Our analysis revealed a significant positive relationship between MDD and both femoral neck osteoporosis (OR = 6.942 [95 % CI, 1.692-28.485]) and trochanteric osteoporosis (OR = 4.140 [95 % CI, 1.699-10.089]). In analyses related to osteopenia, a significant positive correlation was observed between MDD and both total femoral osteopenia (OR = 3.309 [95 % CI, 1.577-6.942]) and trochanteric osteopenia (OR = 2.467 [95 % CI, 1.004-6.062]). Furthermore, in the MR analysis, genetically predicted MDD was causally associated with an increased risk of osteoporosis via the IVW method (P = 0.013). LIMITATIONS: Our study was limited by potential selection bias due to excluding subjects with missing data, and its applicability was primarily to European and American populations. CONCLUSION: Integrating NHANES and MR analyses, a robust correlation between MDD and osteoporosis was identified, emphasizing the significance of addressing this comorbidity within clinical practice and meriting further investigation.

Large scale production of highly-qualified graphene by ultrasonic exfoliation of expanded graphite under the promotion of (NH4)2CO3 decomposition.

Highly-qualified graphene was prepared by the ultrasonic exfoliation of commercial expanded graphite (EG) under the promotion of (NH4)2CO3 decomposition. The yield of graphene from the first exfoliation is 7 wt%, and it can be increased to more than 65 wt% by repeated exfoliations. Atomic force microscopy, x-ray photoelectron spectroscopy and Raman analysis show that the as-prepared graphene only has a few defects or oxides, and more than 95% of the graphene flakes have a thickness of ~1 nm. The electrochemical performance of the as-prepared graphene is comparable to reduced graphene oxide in the determination of dopamine (DA) from the mixed solution of ascorbic acid, uric acid and DA. These results show that the decomposition of (NH4)2CO3 molecules in the EG layers under ultrasonication promotes the exfoliation of graphite and provides a low-priced route for large scale production of highly-quality graphene.

Carbon coated Co-SiC nanocomposite with high-performance microwave absorption.

A carbon coated Co-SiC nanocomposite was fabricated via in situ pyrolysis of methane on a hierarchical Co3O4-SiC nanostructure, which was obtained by hydrothermal synthesis. By the reduction of methane, the Co3O4 was in situ converted to cobalt nanoparticles, and coated by carbon or filled in the CNTs. The as-prepared composite exhibits excellent microwave absorption performance in the frequency range of 2-18 GHz. When the match thickness is 1.8 mm, the composite has a reflection loss value below -10 dB in the range 12.2 to 18 GHz, which nearly covers the whole Ku-band (12-18 GHz). When the thickness is 2.6 mm, the reflection loss value below -10 dB distributes at 8.2-11.5 GHz, covering most of the X-band (8-12 GHz). Moreover, by further tuning the match thickness, the composite can selectively absorb some certain frequency bands of microwaves.

CircSMAD2 accelerates endometrial cancer cell proliferation and metastasis by regulating the miR-1277-5p/MFGE8 axis.

OBJECTIVE: Endometrial cancer (EC) is a common gynecological malignant tumor. CircRNAs play crucial roles in cancer progression and metastasis. However, the biological functions of circRNAs in EC remain largely unknown. METHODS: CircSMAD2, miR-1277-5p, MFGE8 and relative maker protein expression in EC tissues or cell lines were analyzed by quantitative real-time polymerase chain reaction and Western blot. In vitro and in vivo functional assays, including EDU, CCK8, colony formation, transwell, tube formation and tumor xenograft assays, were conduct to explore the effects of circSMAD2 on EC. Mechanism assays were conducted to confirm the binding between miR-1277-5p and circSMAD2 or MFGE8 expression. RESULTS: Upregulation of circSMAD2 was uncovered in both EC tissues and cell lines. Functionally, silencing of circSMAD2 apparently inhibited the proliferation, migration, invasion and angiogenesis of EC cell lines in vitro. Mechanistically, circSMAD2 sponged miR-1277-5p to upregulate MFGE8 expression. The decrease of miR-1277-5p and increase of MFGE8 were observed both in EC tissues and cell lines. Then MFGE8 knockdown or miR-1277-5p upregulation suppressed EC cell oncogenic biological behavior. Rescue experiments showed that miR-1277-5p mimics countervailed the anticancer effects of circSMAD2 silencing on EC. Besides that, MFGE8 overexpression also attenuated the inhibitory action of miR-1277-5p mimic in EC. Moreover, knockdown of circSMAD2 inhibited EC growth in vivo. CONCLUSION: CircSMAD2 functions as an oncogene in promoting the progression of EC through miR-1277-5p/MFGE8 axis.

Management of adverse effects associated with pegylated Escherichia coli asparaginase on coagulation in the treatment of patients with NK/T-cell lymphoma.

ABSTRACT: Natural killer/T-cell lymphoma (NK/TL) is a chemotherapy-sensitive disease, and asparaginase-based chemotherapy has become the standard primary treatment for patients with this malignancy recently. The objective of this study was to evaluate the adverse reactions on blood coagulation of the administered pegylated Escherichia coli (E coli) asparaginase (PEG-ASP) to the NK/TL patients. Clinical data of 71 NK/TL patients (range 13-73 years), who received 239 cycles of chemotherapy treatment containing PEG-ASP in the Hematology Department of Shanxi Province Cancer Hospital of China from January 2016 to December 2019 were analyzed retrospectively. Data of prothrombin time (PT), activated partial thromboplastin time (APTT), fibrinogen (FBG), and antithrombinIII (ATIII) were obtained at the time points routinely and statistically analyzed. There were statistical differences between the monitored parameters of baseline day0 (the day before use of PEG-ASP, named day0) and those of day3 (the 3rd day after treatment) to day6, and data showed all of the indicators could recover within 21 days. The events included PT prolonged in 33 patients (46.5%), APPT prolonged in 41 patients (57.7%, 20 patients with APTT >60 seconds), FBG decreased in 49 patients (69.0%, 12 patients with FBG <1 g/L), and ATIII decreased in 52 patients (73.2%). The patients' average number of cycles received was 2.3 for PT (>14 seconds), 2.5 for APTT (>35 seconds), 2.7 for FBG (<2 g/L), and 2.6 for D-dimer (>550 ng/mL). Compared with those at day0, PT and APTT prolonged sharply at day3 (P < .05), reached the peak at day12, maintained the prolonged level from day3 to day15, and gradually recovered at day 21. FBG and ATIII significantly decreased at day6 and day3 respectively (P < .05), both of them fell to the minimum at day12, and then returned the normal. The D-dimer levels were no significantly change during the whole treatment course. The APTT >60 seconds or FBG <1 g/L side effects were improved by symptomatic treatment of supplementation of fresh frozen plasma or cryoprecipitate infusion, no concomitant bleeding or thrombotic events emerging. Our data suggested although chemotherapy including PEG-ASP impacted moderately on the coagulation function of NK/TL patients, clinically monitored regularly were necessary and most NK/TL patients can complete the chemotherapy cycles successfully.

Preparation of a carbon-based solid acid catalyst by sulfonating activated carbon in a chemical reduction process.

Sulfonated (SO(3)H-bearing) activated carbon (AC-SO(3)H) was synthesized by an aryl diazonium salt reduction process. The obtained material had a SO(3)H density of 0.64 mmol·g-1 and a specific surface area of 602 m2·g-1. The catalytic properties of AC-SO(3)H were compared with that of two commercial solid acid catalysts, Nafion NR50 and Amberlyst-15. In a 10-h esterification reaction of acetic acid with ethanol, the acid conversion with AC-SO(3)H (78%) was lower than that of Amberlyst-15 (86%), which could be attributed to the fact that the SO(3)H density of the sulfonated carbon was lower than that of Amberlyst-15 (4.60 mmol·g-1). However, AC-SO(3)H exhibited comparable and even much higher catalytic activities than the commercial catalysts in the esterification of aliphatic acids with longer carbon chains such as hexanoic acid and decanoic acid, which may be due to the large specific surface area and mesoporous structures of the activated carbon. The disadvantage of AC-SO(3)H is the leaching of SO(3)H group during the reactions.

Synergistic Effect of Segregated Pd and Au Nanoparticles on Semiconducting SiC for Efficient Photocatalytic Hydrogenation of Nitroarenes.

Efficient catalytic hydrogenation of nitroarenes to anilines with molecular hydrogen at room temperature is still a challenge. In this study, this transformation was achieved by using a photocatalyst of SiC-supported segregated Pd and Au nanoparticles. Under visible-light irradiation, the nitrobenzene hydrogenation reached a turnover frequency as high as 1715 h-1 at 25 °C and 0.1 MPa of H2 pressure. This exceptional catalytic activity is attributed to a synergistic effect of Pd and Au nanoparticles on the semiconducting SiC, which is different from the known electronic or ensemble effects in Pd-Au catalysts. This kind of synergism originates from the plasmonic electron injection of Au and the Mott-Schottky contact at the interface between Pd and SiC. This three-component system changes the electronic structures of the SiC surface and produces more active sites to accommodate the active hydrogen that spills over from the surface of Pd. These active hydrogen species have weaker interactions with the SiC surface and thus are more mobile than on an inert support, resulting in an ease in reacting with the N═O bonds in nitrobenzene absorbed on SiC to produce aniline.

Formation mechanism of Si3N4 nanowires via carbothermal reduction of carbonaceous silica xerogels.

Si3N4 nanowires prepared from the carbothermal reduction of carbonaceous silica xerogels with metal salt additives usually contain a small amount of nanotubes. This paper is devoted to the investigation of the formation mechanism of the Si3N4 nanowires. As-prepared samples heated at 1300 degrees C for different reaction times (1, 5, 10, and 30 h) were characterized by X-ray diffraction, Fourier transform infrared spectroscopy, scanning electron microscopy, and energy-dispersive X-ray spectroscopy. The results showed that all the samples mainly consisted of nanowires, while their crystalline phases changed with the heating time. Nitrogen-doped silicon oxide nanowires were first produced via the vapor-liquid-solid process and then underwent a stepwise surface nitrogenization to silicon nitride. The suggested mechanism can easily explain the existence of nanotubes in the Si3N4 nanowires.

[Experimental study on lung injury and cell cycle changes in mice induced by bitumen fume].

OBJECTIVE: To investigate the carcinogenic and mutagenic mechanism of bitumen fume. METHODS: The experimental mice were forced to inhale the bitumen fume at different exposure level (55 mg/m(3), 165 mg/m(3)) and in different time (30 days, 60 days). The pathological changes of the lung tissue in mice were observed with H.E staining. The content of the DNA in the lung tissue of mice and the cell circles were determined with flow cytometry. RESULTS: The lesion of the lung tissue in mice comprised the atypical hyperplasia of different levels and the carcinoma in situ with the increase of the containment time and dosage; the cycle index was changed: the number of the G 1 phase cells was decreased, the S phase was retarded, the cells entering the G 2/S phase were decreased, the cell proliferation index (P I) was increased and the heteroploid DNA index (DI) was increased (P < 0.05). The cell index in the 55 mg/m(3) group and the 165 mg/m(3) group was higher than that in the control group when the containment time was same. The heteroploid DNA index (DI) in the 55 mg/m(3) group was significantly higher than that in the 165 mg/m(3) group (P < 0.05 or P < 0.01). When the containment dosage was same, the DI in the 60 days treatment group (1.16 +/- 1.51 x 10(-2), 1.20 +/- 2.3 x 10(-2)) was all significantly higher than those in the 30 days treatment group (1.14 +/- 8.8 x 10(-2), 1.16 +/- 1.47 x 10(-2)) (P < 0.05). CONCLUSION: The precancerous lesion in the lung tissue of the mice induced by the bitumen fume may be related with the changes of the cell cycle.