Foam Accumulation Research Articles

Foam Segmentation in Wastewater Treatment Plants

The excessive accumulation of foam in wastewater treatment plant (WWTP) tanks can impede proper aeration, hindering the effective removal of organic matter from the water. This study proposes a novel technique to monitor in real time the presence of foams in WWTP tanks by using texture segmentation models trained with centralized and federated approaches. These models are designed to segment the foam and quantify the percentage of foam coverage across the entire tank surface. This data provides plant operators with crucial information for identifying the optimal time for foam removal. The proposed methodology is integrated into an image processing pipeline that involves acquiring images using a PTZ camera, ensuring the absence of anomalies in the captured images, and implementing a real-time communication method for event notifications to plant operators. The models exhibit noteworthy performance, achieving an 86% Dice score in foam segmentation, with comparable results obtained through both centralized and federated training. Implemented in a wastewater treatment plant, this integrated pipeline enhances operational efficiency while concurrently reducing costs.

Respon Histologis Aorta dan Jantung Rattus Norvegicus Hiperlipidemia Setelah Pemberian Jus Buah Kersen (Muntingia calabura L.) dan Ekstrak Daun Lakum (Cayratia trifolia L.)

This study aims to determine the histological features of the aorta and heart of male Rattus norvegicus after administration of cherry juice (Muntingia calabura L.) dan lakum leaf extract (Cayratia trifolia L.). The study used 30 male Rattus norvegicus L. in a Completely Randomized Design (CRD) consisting of 5 treatments with 6 repetitions, namely the control group (P0), the standard feeding group (P1), the hyperlipid feed group + 0.2 mL/200 g BB cherry juice (P2), the hyperlipid feed group + 40 mg / 200 g BB lakum leaf extract (P3) and hyperlipid feed group + 0.18 mg / 200 g BB simvastatin (P4). Hyperlipid feed was given during the treatment, which was 28 days. To obtain histological data, preparations were made using the paraffin method and then observed using a photomicrograph with 400x magnification and observing the aortic lumen, foam cells and intracellular accumulation of lipids in smooth muscle. Data were analyzed by ANOVA followed by Duncan Test at a significant level of 5%. The results showed that the addition of cherry juice and lakum leaf extract gave a significant effect on lumen width and thickness of the aortic wall (p <0.05), while on changes in heart muscle cell size no significant effect (p> 0.05). Histomorphometri showed the presence of foam cells and accumulation of smooth muscle lipids in the control and group treatments with hyperlipid feeding. The conclusion of this study was that the addition of cherry juice and lakum leaf extract can reduce atherosclerotic lesions by eliminating showed foam cells and prevent proliferating smooth muscle cells so the size of the aortic lumen width returns to normal, but didn’t cause enlargement of the heart muscle (cardiomegaly).

Microbial assemblages and methanogenesis pathways impact methane production and foaming in manure deep-pit storages.

Foam accumulation in swine manure deep-pits has been linked to explosions and flash fires that pose devastating threats to humans and livestock. It is clear that methane accumulation within these pits is the fuel for the fire; it is not understood what microbial drivers cause the accumulation and stabilization of methane. Here, we conducted a 13-month field study to survey the physical, chemical, and biological changes of pit-manure across 46 farms in Iowa. Our results showed that an increased methane production rate was associated with less digestible feed ingredients, suggesting that diet influences the storage pit's microbiome. Targeted sequencing of the bacterial 16S rRNA and archaeal mcrA genes was used to identify microbial communities' role and influence. We found that microbial communities in foaming and non-foaming manure were significantly different, and that the bacterial communities of foaming manure were more stable than those of non-foaming manure. Foaming manure methanogen communities were enriched with uncharacterized methanogens whose presence strongly correlated with high methane production rates. We also observed strong correlations between feed ration, manure characteristics, and the relative abundance of specific taxa, suggesting that manure foaming is linked to microbial community assemblage driven by efficient free long-chain fatty acid degradation by hydrogenotrophic methanogenesis.

High glucose macrophage exosomes enhance atherosclerosis by driving cellular proliferation & hematopoiesis

SummaryWe investigated whether extracellular vesicles (EVs) produced under hyperglycemic conditions could communicate signaling to drive atherosclerosis. We did so by treating Apoe−/− mice with exosomes produced by bone marrow-derived macrophages (BMDM) exposed to high glucose (BMDM–HG-exo) or control. Infusions of BMDM–HG-exo increased hematopoiesis, circulating myeloid cell numbers, and atherosclerotic lesions with an accumulation of macrophage foam and apoptotic cells. Transcriptome-wide analysis of cultured macrophages treated with BMDM–HG-exo or plasma EVs isolated from subjects with type II diabetes revealed a reduced inflammatory state and increased metabolic activity. Furthermore, BMDM–HG-exo induced cell proliferation and reprogrammed energy metabolism by increasing glycolytic activity. Lastly, profiling microRNA in BMDM–HG-exo and plasma EVs from diabetic subjects with advanced atherosclerosis converged on miR-486-5p as commonly enriched and recognized in dysregulated hematopoiesis and Abca1 control. Together, our findings show that EVs serve to communicate detrimental properties of hyperglycemia to accelerate atherosclerosis in diabetes.

Foam-Resilient Distillation Processes\u2014Influence of Pentosan and Thermal Energy Input on Foam Accumulation in Rye Mash Distillation

Foaming of mashes during distillation is a common problem encountered in spirit drink production. It has a negative impact on the purity of the final product. This research article presents the key aspects of foam accumulation in rye mashes during distillation. Foam accumulation was influenced by substrate characteristics and process parameters. The experiments showed that pentosan levels and thermal energy input were the crucial parameters for foam accumulation in rye mashes. Foam accumulation was significantly enhanced by higher pentosan levels, due to the higher viscosity imparted by pentosan. Hence, degradation of pentosans prior to distillation presents a way to reduce foam accumulation. In terms of thermal energy input, foam accumulation was significantly lower when the thermal energy input was reduced from 400 to 200 W/L. Substantial foaming only occurred in a narrow temperature range of 89.5 to 98.2 C. The results allowed for the first time to make recommendations to prevent problematic foam accumulation during distillation of rye mashes.

Lack of match between nutrient-enriched marine seafoam and intertidal abundance of long-lived invertebrate larvae

Since most marine benthic species experience a pelagic larval phase, scales of dispersal are key determinants of population dynamics. Biologically derived marine foam has been suggested to increase chances of fertilisation and reduce dispersal of larvae of short-live duration (hours), thus maintaining localised intertidal populations. The present study examined the role sea-foam plays as a mechanism of physical retention/accumulation for long lived (weeks) invertebrate larvae that are relatively long-lived (weeks). Larvae were collected using a submersible pump at two sites along the south-east coast of South Africa, where intertidal assemblages are dominated by beds of mussels and barnacles. Sampling took place on six occasions in 2015–2016, during events of high sea-foam production and periods of no foam accumulation. Foam/water was collected from the surface and bottom of tidal channels. There was no difference in abundance of larvae of any of the invertebrate taxa examined, whether foam was present or absent. Regardless of foam state, barnacle and polychaete larvae were mostly associated with the surface of the short water column at the tidal channels. This study highlights how the very nearshore environment may play a key role in limiting scales of larval dispersal, but especially how the effects of physical processes can be taxon-specific, depending on the larval duration and characteristics.

Aerosol Toxins Emitted by Harmful Algal Blooms Susceptible to Complex Air-Sea Interactions.

Critical research is needed regarding harmful algal blooms threatening ecosystem and human health, especially through respiratory routes. Additional complexity comes from the poorly understood factors involved in the physical production of marine aerosols coupled with complex biogeochemical processes at ocean surfaces. Here-by using a marine aerosol generation tank-five bubble-bursting experiments (with contrasting incubation times and, likely, physiological microalgal states) were run to investigate simultaneously the concentrations of the toxins, synthesized by a natural Ostreopsis cf. ovata bloom, in suspension in the water and in the atmosphere. The first two experiments (EXP1-2) were run with moderate levels of O. cf. ovata cell numbers (ca. 105 cells·L-1) and total toxin in suspension (4 × 106 pg·Lwater-1) obtained at an early phase of the bloom. After 0.75-4 h incubation, toxin concentration in the aerosols accounted for 49-69 pg·Lair-1. By striking contrast, three experiments (EXP3-5)-conducted with samples collected two weeks later with higher cell abundances and higher toxin concentration in the seston (respectively, about 1 × 106 cells·L-1 and 2 × 108 pg·Lwater-1) and incubated for 21 h-showed about 15-fold lower atmospheric concentrations (3-4 pg·Lair-1), while important foam accumulation was observed in the water surface in the tank. Offline spectroscopic analysis performed by proton-nuclear magnetic resonance spectroscopy showed that the particulate organic carbon in the water was drastically different from that of bubble-bursting aerosols from the tank experiments-suggesting a selective transfer of organic compounds from seawater into the atmosphere. Overall, the results suggest that aerosol production and diffusion of marine toxins in the atmosphere are regulated by complex interactions between biological processes and air-sea aerosol production dynamics.

Histologic response of aortic Rattus norvegicus male strain wistar hyperlipidemia after giving kersen fruits juice and extract lakum leaves

People lifestyle who tend to consume high fat diet is one of the risk factors causing cardiovascular diseases such as atherosclerosis and coronary heart disease. The aims of this study were to analyze the effect of kersenfruits juice and extract lakum leaves on lumen width and thickness of aortic wall and to find out the histological features of male Rattusnorvegicus white rats due to hiperlipemia. The study used a Completely Randomized Design (CRD) consisting of 5 treatments with 4 replications, i.e. the control group (P0), the standard feeding group (P1), the hyperlipid feed group+0.2 mL/200gBB kersen juice (P2), the hyperlipid feed group+40mg / 200gBB extract lakum leaves (P3) and hyperlipid feed group +0.18mg / 200gBB simvastatin (P4). Hyperlipid feeds were given for 28 days. Data were analyzed by ANOVA followed by Duncan Test at a confidence level of 95, while histological features were observed directly using photomicrograph with 400x magnification and were seen aortic lumen narrowing, foam cells and intracellular lipid accumulation in smooth muscle. The results showed that the addition of kersenfruits juice and extract lakum leaves gave a significant effect on lumen width and thickness of the aortic wall (p <0.05). Histological features show the presence of foam cells and accumulation of smooth muscle lipids in the control and group treatments with hyperlipemia feeding. The conclusion of this study is that the addition of kersen juice fruits and extract lakum leaves can reduce atherosclerotic lesions by eliminating foam cells and proliferating smooth muscle cells so the size of the aortic lumen width returns to normal.

Effect of an amine phosphate addition on the foaming characteristics in turbine base oil

Foaming tendency of turbine oil is diverse due to the variance in turbine oil components, including the type and content of additives and base oils. A common amine phosphate (AP) was investigated as an anti-wear additive in turbine oil. According to ASTM D892, the AP exhibited severe foam accumulation when blended with five kinds of polyol esters, respectively. There is a positive correlation between foam accumulation volume and elasticity modulus. Moreover, adding 0.02 wt% defoamer (T921) could reduce foam accumulation volume and elasticity modulus effectively.

The Role of Smooth Myocytes and Macrophages in Development of Complicated Forms of Arterial Atherosclerosis

to conduct morphohistochemical and immunohistochemical study of arterial unstable atherosclerotic plaques for assessment of the state of smooth muscle cells (SMC) and macrophages. The surgical material of the peripheral arteries (femoral, popliteal, external carotid) was obtained from 50 patients aged over 60 years, followed by morphohistochemical, immunohistochemical studies. Hyperplasia of secretory smooth muscle cells (SMC), and new formation of thin-walled capillary vessels was noted in unstable atherosclerotic plaques. Macrophagic infiltration was detected in the intima of arteries, in places of accumulation of foam cells. Unstable atherosclerotic plaque is a cellular-intercellular process with the participation of lipids, macrophages, and with predominance of SMC and newly formed vessels.

Narasin as a Manure Additive to Reduce Methane Production from Swine Manure

Abstract. High levels of methane production from swine operations have been associated with foam accumulation in deep-pit manure storage systems. This foam poses both a safety concern (i.e., flash fires) and operational challenges in managing stored manure. Mitigating methane production is one approach to controlling foam accumulation. In this study, swine manures obtained from three deep-pit storage barns in central Iowa were dosed with narasin to evaluate its inhibitory effects on methane and biogas production. Dose rates ranged from 0 to 3.0 mg narasin kg-1 manure. Overall, methane rates were reduced by 9% for each mg of narasin added per kg of manure, and this reduction was effective for up to 25 days. However, the inhibitory effect weakened with time such that no statistical difference in cumulative methane production between samples dosed with narasin and undosed controls could be detected after 120 days of incubation. In addition to methane rates, narasin addition reduced the degradation of total and volatile solids in the manure by 1.9% and 2.6%, respectively, for each mg of narasin added per kg of manure. Additional study treatments included sugar (10 g kg-1 manure) with and without narasin (1.5 mg narasin kg-1 manure). Results from this treatment showed that methane production was initially increased by the sugar addition, but the effect lasted less than six days, at which point cumulative methane production was similar to the control. When treated with both narasin and sugar, the inhibitory effect did not impact gas production during the sugar digestion phase but did reduce methane and biogas production thereafter. The addition of sugar and the rate of narasin addition caused changes to the microbial community as compared to the control. Overall, the results indicated that narasin can be an effective additive for reducing methane emission from swine manure, but further study is needed to recommend dosing frequency and to evaluate how continuous addition of manure impacts narasin effectiveness. Keywords: Biogas, Manure management, Manure treatment, Methane, Narasin, Swine manure, Swine production.

Time scales of foam stability in shallow conduits: Insights from analogue experiments

AbstractVolcanic systems can exhibit periodical trends in degassing activity, characterized by a wide range of time scales. Understanding the dynamics that control such periodic behavior can provide a picture of the processes occurring in the feeding system. Toward this end, we analyzed the periodicity of outgassing in a series of decompression experiments performed on analogue material (argon‐saturated silicone oil plus glass beads/fibers) scaled to serve as models of basaltic magma. To define the effects of liquid viscosity and crystal content on the time scale of outgassing, we investigated both: (1) pure liquid systems, at differing viscosities (100 and 1000 Pa s), and (2) particle‐bearing suspensions (diluted and semidiluted). The results indicate that under dynamic conditions (e.g., decompressive bubble growth and fluid ascent within the conduit), the periodicity of foam disruption may be up to several orders of magnitude less than estimates based on the analysis of static conditions. This difference in foam disruption time scale is inferred to result from the contribution of bubble shear and bubble growth to inter‐bubble film thinning. The presence of particles in the semidiluted regime is further linked to shorter bubble bursting times, likely resulting from contributions of the presence of a solid network and coalescence processes to the relative increase in bubble breakup rates. Finally, it is argued that these experiments represent a good analogue of gas‐piston activity (i.e., the periodical rise‐and‐fall of a basaltic lava lake surface), implying a dominant role for shallow foam accumulation as a source process for these phenomena.

Impact of fiber source and feed particle size on swine manure properties related to spontaneous foam formation during anaerobic decomposition

Foam accumulation in deep-pit manure storage facilities is of concern for swine producers because of the logistical and safety-related problems it creates. A feeding trial was performed to evaluate the impact of feed grind size, fiber source, and manure inoculation on foaming characteristics. Animals were fed: (1) C–SBM (corn–soybean meal): (2) C–DDGS (corn–dried distiller grains with solubles); and (3) C–Soybean Hull (corn–soybean meal with soybean hulls) with each diet ground to either fine (374μm) or coarse (631μm) particle size. Two sets of 24 pigs were fed and their manure collected. Factors that decreased feed digestibility (larger grind size and increased fiber content) resulted in increased solids loading to the manure, greater foaming characteristics, more particles in the critical particle size range (2–25μm), and a greater biological activity/potential.

An Evaluation of the Physicochemical and Biological Characteristics of Foaming Swine Manure

<abstract> <b><sc>Abstract.</sc></b> Foam accumulation in deep-pit manure storages is an increasing concern for swine producers because of the logistical and safety-related problems it creates. To investigate this phenomenon, samples of swine manure were collected over a 13-month period from 58 swine production facilities in Iowa with varying levels of foam accumulation. Samples were tested for a number of physical, chemical, and biological parameters including pH, total and volatile solids, volatile fatty acid concentration, long-chain free fatty acid concentration, biochemical methane potential, methane production rate, surface tension, foaming capacity, and foam stability. Statistical analysis indicated that manure collected from facilities with foam accumulation produced methane at significantly (p < 0.05) faster rates than non-foaming manures (0.148 ±0.004 and 0.049 ±0.003 L CH₄ L^-1 slurry d^-1, respectively) and consequently had significantly (p < 0.05) greater fluxes of biogas moving through the manure. The biochemical methane production assay suggested that manure from foaming pits had less potential to generate methane (123 ±9 mL CH₄ g^-1 VS) than manure from non-foaming pits (150 ±9 mL CH₄ g^-1 VS), presumably because more of the methane potential had previously been consumed, as indicated by the higher methane production rates. Short-chain fatty acid concentrations were significantly lower in foaming manures (4200 ±570 mg kg^-1) than non-foaming manures (9470 ±730 mg kg^-1). The methane production rate, biochemical methane potential, and short-chain fatty acid assays suggest enhanced anaerobic digestion efficiency from foaming barns as compared to non-foaming barns. Other assays, such as surface tension and foaming capacity, indicated an accumulation of a surfactant at the manure-air interface of the foam, which may be capturing biogas bubbles generated within the manure. Most importantly, the foam layers exhibited a greatly enhanced ability to stabilize bubbles, which appeared to be correlated to the higher solids concentrations that stabilize the bubbles.

Experimental investigation of fire extinguishment using expansion foam in the underground goaf

Mine fire is a serious environment, health, and safety hazard throughout the world. Through analyzing the drawbacks of traditional extinguishing techniques on dealing with fire at top of goaf, we propose a new foam preparation method to make extinguishing foam. It uses a jet device to add foaming agent and a foam generator to produce foam. The driving powers are water pressure and compressed gas, which have strong intrinsic safety for application in underground coal mines. Testing results show that foam diffuses fast at the initial stage of infusion in the goaf, while the foam diffusion velocity finally maintains at 0.0084–0.0087 m/s. With a large tensile deformation, the foam flowing through a fracture aisle is within 0.4 s. The expansion foam accumulates upwards until it extinguishes fire at top of the goaf, making a sharp decrease on the fire source temperatures. It is feasible that foam is infused into the goaf discontinuously with an interval time less than the foam half-life to get a reasonable economic cost input and a good foam accumulation in the goaf.

Pathological findings in wild harvested dugongs Dugong dugon of central Torres Strait, Australia.

The dugong Dugong dugon is classified as Vulnerable to extinction but may be endangered in some regions. Cause of death in stranded dugongs has not been determined in a large proportion of animals examined, with investigations hindered by limited information on dugong health and diseases, and paucity of knowledge of common or endemic pathological findings. Here we describe pathological findings in harvested dugongs from the relatively pristine area of central Torres Strait, and we characterise lesions attributable to drowning. Other recorded lesions were mild and predominated by host reaction to the presence of trematodes within the gastrointestinal tracts, liver and pancreas. Ascarid worm burdens were low in comparison to dugongs from developed coastlines. Hepatocellular lipofuscin and ferritin pigmentation were commonly observed, more pronounced in livers of older animals and concurrent with periportal and bridging fibrosis. Lesions attributable to drowning included incomplete collapse of lungs, dorsal or diffuse pulmonary congestion, mild intra-alveolar haemorrhage and oedema, mild interstitial oedema and rupture of peripheral alveolar septae with acute myofibre fragmentation and degeneration. No accumulation of foam or aspiration of water or particulate matter was observed, suggesting that dugongs 'dry drown'. Morphometric features of normal spleen are also presented. Characterisation of common pathological findings and those attributable to drowning in this species will aid in the interpretation of post mortem findings for the significant number of dugongs found deceased along urbanised coastlines.

Direct aerosol chemical composition measurements to evaluate the physicochemical differences between controlled sea spray aerosol generation schemes

Abstract. Controlled laboratory studies of the physical and chemical properties of sea spray aerosol (SSA) must be under-pinned by a physically and chemically accurate representation of the bubble-mediated production of nascent SSA particles. Bubble bursting is sensitive to the physico-chemical properties of seawater. For a sample of seawater, any important differences in the SSA production mechanism are projected into the composition of the aerosol particles produced. Using direct chemical measurements of SSA at the single-particle level, this study presents an intercomparison of three laboratory-based, bubble-mediated SSA production schemes: gas forced through submerged sintered glass filters ("frits"), a pulsed plunging-waterfall apparatus, and breaking waves in a wave channel filled with natural seawater. The size-resolved chemical composition of SSA particles produced by breaking waves is more similar to particles produced by the plunging waterfall than those produced by sintered glass filters. Aerosol generated by disintegrating foam produced by sintered glass filters contained a larger fraction of organic-enriched particles and a different size-resolved elemental composition, especially in the 0.8–2 μm dry diameter range. Interestingly, chemical differences between the methods only emerged when the particles were chemically analyzed at the single-particle level as a function of size; averaging the elemental composition of all particles across all sizes masked the differences between the SSA samples. When dried, SSA generated by the sintered glass filters had the highest fraction of particles with spherical morphology compared to the more cubic structure expected for pure NaCl particles produced when the particle contains relatively little organic carbon. In addition to an intercomparison of three SSA production methods, the role of the episodic or "pulsed" nature of the waterfall method on SSA composition was under-taken. In organic-enriched seawater, the continuous operation of the plunging waterfall resulted in the accumulation of surface foam and an over-expression of organic matter in SSA particles compared to those produced by a pulsed plunging waterfall. Throughout this set of experiments, comparative differences in the SSA number size distribution were coincident with differences in aerosol particle composition, indicating that the production mechanism of SSA exerts important controls on both the physical and chemical properties of the resulting aerosol with respect to both the internal and external mixing state of particles. This study provides insight into the inextricable physicochemical differences between each of the bubble-mediated SSA generation mechanisms tested and the aerosol particles that they produce, and also serves as a guideline for future laboratory studies of SSA particles.

Volutrauma and Regional Ventilation Revisited

Volutrauma and Regional Ventilation Revisited

Do transparent exopolymeric particles (TEP) derived from Phaeocystis globosa bloom impact the physiological performances of European sea bass juveniles

A mesocosm experiment (1m3 enclosures) was carried out over 28days to evaluate the effect of Transparent Exopolymer Particles (TEP) derived from decaying Phaeocystis globosa colonies on the physiological performance and mortality of European sea bass juveniles (35mm in length and 113days old). Accordingly, sea bass juveniles were exposed to high TEP concentrations derived from both a culture of decaying P. globosa colonies (7634.27±3514.41μgXGeqL−1) and freshly sea foam (932.54±341.21μgXGeqL−1). During the experiment, environmental parameters (pH, dissolved oxygen, temperature and salinity) were stable, similar among treatments and not limiting for growth. Only TEP concentration varied between treatments. Fish mortality rate was relatively low (0 to 2%d−1) and mostly occurred during the first week when TEP concentrations were relatively low. Despite high and varying TEP concentrations, juvenile sea bass physiological performances (growth in length and weight, Fulton condition index and RNA–DNA ratio) did not differ between replicates and treatments. In addition, juvenile sea bass increased both in size by 7.2mm (growth rate of 0.26mmd−1) and weight by 708mg (growth rate of 25.29mgd−1) during the 28days of the experiment. Altogether, these results showed clearly that TEP derived from decaying P. globosa bloom and foam accumulation have no negative effect on juvenile sea bass physiological performances and survival if water dissolved oxygen is maintained high. Despite being one of the most recurrent phytoplankton blooms recorded in the northwest European shelf seas and forms large blooms in the coastal waters during spring, we suggest that Phaeocystis bloom has no deleterious effect on marine coastal fish aquaculture activities.

Homocysteine-mediated cholesterol efflux via &amp;lt;italic&amp;gt;ABCA1&amp;lt;/italic&amp;gt; and &amp;lt;italic&amp;gt;ACAT1&amp;lt;/italic&amp;gt; DNA methylation in THP-1 monocyte-derived foam cells

Homocysteine (Hcy) has been recognized as a prevalent risk factor for cardiovascular events. Cholesterol-loaded foam cells are a central component of atherosclerotic lesions. ATP-binding cassette transporter A1 (ABCA1), which mediates the efflux of cellular cholesterol and phospholipids, is the rate-limiting step in lipid metabolism. Acyl-coenzyme A:cholesterol acyltransferase-1 (ACAT1) promotes accumulation of cholesterol ester in macrophages, thereby resulting in the foam cell formation, a hallmark of early stage in atherosclerosis. In this study, cultured monocyte-derived foam cells were incubated with clinical relevant concentrations of Hcy for 24 h. Both increased number of foam cells and accumulation of cholesterol were found, and the mRNA and protein expression levels of ABCA1 were decreased, while ACAT1 expression was increased in the presence of Hcy. Furthermore, the DNA methylation level of ABCA1 gene was increased whereas ACAT1 DNA methylation was decreased by using different concentrations of Hcy. Moreover, our results showed that DNA methyltransferase (DNMT) activity and DNA methyltransferase 1 (DNMT1) mRNA expression were increased by Hcy. It is indicated that DNA methylation has the function to regulate the expression of ABCA1 and ACAT1 via DNMT. In conclusion, these results suggest that ABCA1 and ACAT1 DNA methylation induced by Hcy may play a potential role in ABCA1 and ACAT1 expression and the accumulation of cholesterol in monocyte-derived foam cells.