Pomegranate juice inhibits oxidized LDL uptake and cholesterol biosynthesis in macrophages

Macrophage cholesterol accumulation and foam cell formation are the hallmarks of early atherogenesis. Pomegranate juice (PJ) was shown to inhibit macrophage foam cell formation and development of atherosclerotic lesions. The aim of this study was to elucidate possible mechanisms by which PJ reduces cholesterol accumulation in macrophages. J774.A1 macrophages were preincubated with PJ followed by analysis of cholesterol influx [evaluated as LDL or as oxidized LDL (Ox-LDL) cellular degradation], cholesterol efflux and cholesterol biosynthesis. Preincubation of macrophages with PJ resulted in a significant reduction (P<.01) in Ox-LDL degradation by 40%. On the contrary, PJ had no effect on macrophage degradation of native LDL or on macrophage cholesterol efflux. Macrophage cholesterol biosynthesis was inhibited by 50% (P<.01) after cell incubation with PJ. This inhibition, however, was not mediated at the 3-hydroxy-3 methylglutaryl coenzyme A reductase level along the biosynthetic pathway. We conclude that PJ-mediated suppression of Ox-LDL degradation and of cholesterol biosynthesis in macrophages can lead to reduced cellular cholesterol accumulation and foam cell formation.     

Biosynthesis of pullulan using immobilized Aureobasidium pullulans cells

Immobilization of Aureobasidium pullulans by adsorption on solid supports and entrapment in open pore polyurethane foam were attempted. By adsorption, the highest cell loading of 0.012-0.018 g dry wt/cm(2) support was obtained in pH 2.0 medium. Under this acidic condition, the net surface charges (zeta potentials) of both the cells and supports were close to zero and no pullulan was synthesized. Cationic coatings of Cytodex and polyethylenimine were not efficient in enhancing the binding strength between the cells and the supports. Surface immobilized cells and polyurethane foam entrapped cells exhibited a similar fermentation characteristics resulting in ca. 18 g/L pullulan and ca. 5 g/L leaked cells. However, cells entrapped in the polyurethane foam were more shear resistant. The immobilized cells thus could be repeatedly used for pullulan biosynthesis.     

Spatio-Temporal Distributions of Metal Ions and Taxol of Taxus cuspidata Cells Immobilized on Polyurethane Foam

Distinct spatio-temporal variations of metal ions and Taxol production were observed for Taxus cuspidata cells immobilized on polyurethane foam. The Taxol content in the inner foam layer reached 215 μg g⁻¹ at day 30, which was 40-fold higher than that in the outer foam layer, and the Ca²⁺ and Mg²⁺ contents were 5.3 and 3.7 times higher, while the K⁺ content was 5.5 times lower. Thus higher intracellular Ca²⁺ and Mg²⁺ contents and lower intracellular K⁺ content may favor the Taxol biosynthesis in immobilized Taxus cuspidata.     

The Importance of GLUT3 for De Novo Lipogenesis in Hypoxia-Induced Lipid Loading of Human Macrophages

Atherosclerotic lesions are characterized by lipid-loaded macrophages (foam cells) and hypoxic regions. Although it is well established that foam cells are produced by uptake of cholesterol from oxidized LDL, we previously showed that hypoxia also promotes foam cell formation even in the absence of exogenous lipids. The hypoxia-induced lipid accumulation results from increased triglyceride biosynthesis but the exact mechanism is unknown. Our aim was to investigate the importance of glucose in promoting hypoxia-induced de novo lipid synthesis in human macrophages. In the absence of exogenous lipids, extracellular glucose promoted the accumulation of Oil Red O-stained lipid droplets in human monocyte-derived macrophages in a concentration-dependent manner. Lipid droplet accumulation was higher in macrophages exposed to hypoxia at all assessed concentrations of glucose. Importantly, triglyceride synthesis from glucose was increased in hypoxic macrophages. GLUT3 was highly expressed in macrophage-rich and hypoxic regions of human carotid atherosclerotic plaques and in macrophages isolated from these plaques. In human monocyte-derived macrophages, hypoxia increased expression of both GLUT3 mRNA and protein, and knockdown of GLUT3 with siRNA significantly reduced both glucose uptake and lipid droplet accumulation. In conclusion, we have shown that hypoxia-induced increases in glucose uptake through GLUT3 are important for lipid synthesis in macrophages, and may contribute to foam cell formation in hypoxic regions of atherosclerotic lesions.     

Mass exchange conditions in penicillin biosynthesis in an industrial fermenter with aerodynamic foam suppressor

The mass exchange characteristics of 50 m3 industrial fermentors with aerodynamic foam suppression and the effect of the specific power input on biosynthesis of penicillin were studied. A change in the specific power input from 1.3 to 1.9 kW/m3 had no effect on the level of the antibiotic accumulation when the medium with 8 per cent of lactose was used. An increase in the aeration rate from 1 to 1.2 m3/m3 X min provided a 1.1-fold increase in the penicillin activity of the fermentation broth. The use of the device for aerodynamic foam suppression with a system of automatic control of the partial pressure of dissolved carbon dioxide allowed decreasing 1.22-fold the oil use and increasing the process productivity by 10 per cent.     

Oxidative stress leads to cholesterol accumulation in vascular smooth muscle cells.

The transformation of macrophages and smooth muscle cells into foam cells by modified low-density lipoproteins (LDL) is one of the key events of atherogenesis. Effects of free radicals have mainly been studied in LDL, and other than toxicity, data dealing with direct action of free radicals on cells are scarce. This study focused on the direct effects of free radicals on cholesterol metabolism of smooth muscle cells. A free radical generator, azobis-amidinopropane dihydrochloride, was used, and conditions for a standardized oxidative stress were set up in vascular smooth muscle cells. After free radical action, the cells presented an accumulation of cholesterol that appeared to be the result of: (i) an increase in cholesterol biosynthesis and esterification; (ii) a decrease in cell cholesteryl ester hydrolysis; and (iii) a reduced cholesterol efflux. All these parameters were opposed by antioxidants. In addition, oxidant stress induced an increased degradation of acetyl-LDL, whereas no change was noted for native LDL. From this data, it was concluded that cholesterol metabolism of vascular smooth muscle cells was markedly altered by in vitro treatment with free radicals, although cell viability was unaffected. The resulting disturbance in cholesterol metabolism favors accumulation of cholesterol and cholesteryl esters in vascular cells, and thus may contribute to the formation of smooth muscle foam cells.     

Paraoxonases 1, 2, and 3, oxidative stress, and macrophage foam cell formation during atherosclerosis development

Paraoxonases PON1 and PON3, which are both associated in serum with HDL, protect the serum lipids from oxidation, probably as a result of their ability to hydrolyze specific oxidized lipids. The activity of HDL-associated PON1 seems to involve an activity (phospholipase A2-like activity, peroxidase-like activity, lactonase activity) which produces LPC. To study the possible role of PON1 in macrophage foam cell formation and atherogenesis we used macrophages from control mice, from PON1 knockout mice, and from PON1 transgenic mice. Furthermore, we analyzed PON1-treated macrophages and PON1-transfected cells to demonstrate the contribution of PON1 to the attenuation of macrophage cholesterol and oxidized lipid accumulation and foam cell formation. PON1 was shown to inhibit cholesterol influx [by reducing the formation of oxidized LDL (Ox-LDL), increasing the breakdown of specific oxidized lipids in Ox-LDL, and decreasing macrophage uptake of Ox-LDL]. PON1 also inhibits cholesterol biosynthesis and stimulates HDL-mediated cholesterol efflux from macrophages. PON2 and PON3 protect against oxidative stress, with PON2 acting mainly at the cellular level. Whereas serum PON1 and PON3 were inactivated under oxidative stress, macrophage PON2 expression and activity were increased under oxidative stress, probably as a compensatory mechanism against oxidative stress. Intervention to increase the paraoxonases (cellular and humoral) by dietary or pharmacological means can reduce macrophage foam cell formation and attenuate atherosclerosis development.     

LDL Receptor-Related Protein-1 (LRP1) Regulates Cholesterol Accumulation in Macrophages

Within the circulation, cholesterol is transported by lipoprotein particles and is taken up by cells when these particles associate with cellular receptors. In macrophages, excessive lipoprotein particle uptake leads to foam cell formation, which is an early event in the development of atherosclerosis. Currently, mechanisms responsible for foam cell formation are incompletely understood. To date, several macrophage receptors have been identified that contribute to the uptake of modified forms of lipoproteins leading to foam cell formation, but the contribution of the LDL receptor-related protein 1 (LRP1) to this process is not known. To investigate the role of LRP1 in cholesterol accumulation in macrophages, we generated mice with a selective deletion of LRP1 in macrophages on an LDL receptor (LDLR)-deficient background (macLRP1-/-). After feeding mice a high fat diet for 11 weeks, peritoneal macrophages isolated from Lrp ^+/+ mice contained significantly higher levels of total cholesterol than those from macLRP1-/- mice. Further analysis revealed that this was due to increased levels of cholesterol esters. Interestingly, macLRP1-/- mice displayed elevated plasma cholesterol and triglyceride levels resulting from accumulation of large, triglyceride-rich lipoprotein particles in the circulation. This increase did not result from an increase in hepatic VLDL biosynthesis, but rather results from a defect in catabolism of triglyceride-rich lipoprotein particles in macLRP1-/- mice. These studies reveal an important in vivo contribution of macrophage LRP1 to cholesterol homeostasis.     

代谢工程改造大肠杆菌合成己二酸

己二酸是一种具有重要应用价值的二元羧酸,是合成尼龙-66的关键前体。目前,生物法生产己二酸存在生产周期长、生产效率低的问题。本研究选择一株野生型高产琥珀酸菌株大肠杆菌(Escherichia coli) FMME N-2为底盘细胞,首先通过引入逆己二酸降解途径的关键酶,成功构建了可合成0.34 g/L己二酸的E. coli JL00菌株;接着,对合成路径限速酶进行表达优化,使E. coli JL01菌株在摇瓶发酵条件下产量达到0.87 g/L;随后,通过敲除sucD基因、过表达acs基因和突变lpd基因的组合策略平衡己二酸合成前体的供应,优化菌株E. coli JL12己二酸产量进一步提升至1.51 g/L;最后,在5 L发酵罐上对己二酸发酵工艺进行优化。工程菌株经72 h分批补料发酵,己二酸的产量达到22.3 g/L,转化率为0.25 g/g,生产强度为0.31 g/(L·h),具备了一定的应用潜力。本研究可为包括己二酸在内的多种二元羧酸细胞工厂的构建提供理论依据和技术基础。     

Contribution of Disulfide Bonds to the Characteristics of Casein Micelles

Drainage in foam was analyzed by the capillary model proposed by Haas and Johnson. Foam was produced by introducing air into an ovalbumin solution through a spinneret. The electric conductivity at selected positions in the foam and the drained liquid height below the foam were measured at constant intervals. The measured electric conductivity was converted to the liquid volume fraction by Prager’s equation. The capillary model described well not only the liquid leakage rate from foam but also the liquid volume fraction in foam. The ratio of the liquid volume fraction in foam to the volume fraction of the Plateau border was much larger than the value estimated from Haas and Johnson’s result. It was confirmed that a time constant, T, involved in the model was suitable for estimating foam stability only by one parameter. However, T is affected not only by material characteristics but also by the foam height. On the other hand, since the ratio of the liquid volume fraction in foam to the volume fraction of the Plateau border reflects the material characteristics, it may be used for comparing the foam stability between materials with the same viscosity and density.     

Effects of natural oils on foam collapse in bioprocesses

The foam collapse and foam formation properties of four different simulated fermentation media were compared in the presence and absence of natural oils. It was found that optimum effective natural oil concentration resulting in optimum foam suppression did not always correspond with the optimum for foam collapse, nor the optimum for maximum foam collapse rate.     

Espresso coffee foam delays cooling of the liquid phase

Espresso coffee foam, called crema, is known to be a marker of the quality of espresso coffee extraction. However, the role of foam in coffee temperature has not been quantitatively clarified. In this study, we used an automatic machine for espresso coffee extraction. We evaluated whether the foam prepared using the machine was suitable for foam analysis. After extraction, the percentage and consistency of the foam were measured using various techniques, and changes in the foam volume were tracked over time. Our extraction method, therefore, allowed consistent preparation of high-quality foam. We also quantitatively determined that the foam phase slowed cooling of the liquid phase after extraction. High-quality foam plays an important role in delaying the cooling of espresso coffee.     

Cloacal gland foam enhances motility and disaggregation of spermatozoa in Japanese quail (Coturnix japonica)

The adult male Japanese quail produces white foam from the cloacal gland, which is transferred to the female proctodeum during natural mating. The physiological role of foam on quail spermatozoa is still unclear. Therefore, attempts have been made to understand the effect of cloacal foam on motility and metabolism of quail spermatozoa. The profile of various biochemical constitutes in the foam extract was investigated. The addition of foam extract to neat semen completely disaggregated the clumps of spermatozoa leading to vigorous motility. The metabolic rate (MBRT) of the spermatozoa was significantly increased with the addition of foam extract. The foam extract was sub fractionated into seven different fractions by using the molecular cut off devices. Among all the seven sub-fractions from the foam extract, the addition of < 1 KDa sub-fraction contained lactate and has enhanced sperm motility and metabolism. Another fraction (3-10 KDa) has non-protein and non-heparin components which completely disaggregated the clumped quail spermatozoa. However, the remaining fractions did not show any effect on quail spermatozoa. It can be concluded from the present investigation that the lactate present in foam might be a fuel for sperm metabolism and motility. Furthermore, low molecular weight (3-10 KDa) components in the foam may responsible for sperm disaggregation.     

Mechanisms for enhanced biodegradation of petroleum hydrocarbons by a microbe-colonized gas-liquid foam

AIMS: A microbe-colonized gas-liquid foam formulation has been previously shown to provide enhanced biodegradation capabilities in soil microcosms. The present study considers the reservoir properties of this foam and how this affects hydrocarbon degradation rates. METHODS AND RESULTS: Oxygen solubility in protein hydrolysate solutions draining from aerated and oxygenated foams was measured. The suitability of oxygenated foam to enhance the degradation of n-hexadecane in soil microcosms was assessed. Sorption of bacterial isolates at the gas-liquid interface was also investigated using a range of microscopy techniques. CONCLUSIONS: Oxygenated bioactive foam enhanced biodegradation rates by improving oxygen availability and transfer. Biodegradation of n-hexadecane was also stimulated by the protein hydrolysate used and by the inclusion of known bacterial hydrocarbon-degrading bacteria. The interaction of bacteria with the gas-liquid interface was shown to be a significant factor governing the drainage of the bacteria from the bioactive foam. SIGNIFICANCE AND IMPACT OF THE STUDY: Protein hydrolysate-based bioactive foam may be a suitable treatment technology to enhance the biodegradation of petroleum hydrocarbons in soil.     

Cultivation of Bacillus thuringiensis in an airlift reactor with wire mesh draft tubes

An aeration strategy was proposed for foam control in an airlift reactor with double wire mesh draft tubes. The airlift reactor was employed in the cultivation of Bacillus thuringiensis for thuringiensin production. The aeration strategy involved two situations. If the foam rose and touched the foam probe, the air flow rate was dropped to a low value for a certain period. However, if the DO value was already below 10% of the saturation when the air flow rate was dropped, the conventional foam control was employed. The production of thuringiensin based on the proposed strategy was up to 70% higher than that of using the conventional cultivation method with addition of antifoam agents for foam control.     

Influence of foam thickness on the control of EMG activity during a step-down task in females

Compliant foams can be used to mitigate ground reaction forces. However, it is unknown how foam surfaces influence the modulation of leg muscle activity. Thus, the current study aimed to investigate how the neuromuscular system managed changes in expected loading due to various thickness of foam placed on the landing surface during a step down task. The surface electromyographic signal (sEMG) pre-activation duration and the root mean square (RMS) amplitude of tibialis anterior (TA), lateral gastrocnemius (LG), and vastus medialis (VM) of 10 active females were measured as they stepped-down with a single leg onto polyurethane foam slabs of varying thickness (0–50 mm). Pre-activation duration was not affected by the thickness of the foam padding. LG RMS amplitude was less in the foam conditions than the control (no– foam) condition, with the greatest reduction observed for the 50 mm foam condition. In some trials, the muscles remained active throughout the step-down task. In such instances, a sEMG onset time and thus a pre-activation duration could not be determined. All foam conditions significantly increased the odds of continuous muscle activity above that of the no-foam condition. The results indicate that foam surfaces may alter the modulation of muscle activity during step-down tasks.     

Effects of jet-fuel microbial isolates on a polyurethane foam

Jet-fuel microbial isolates were studied for effects on a polyurethane foam material that has been proposed as a baffling material for use in aircraft fuel tanks. Evidence was found that a polyesterurethane foam gave increased cell counts and oxygen uptake with a bacterial isolate, and extensive matting with fragmentation and decreases in tensile strength of the foam with a fungal isolate. The polyurethane foam was affected by activity of the jet-fuel microbial isolates to an extent that would cause serious microbiological problems in the fuel tanks of jet aircraft.     

Covalent binding of a nerve agent hydrolyzing enzyme within polyurethane foams

A phosphotriesterase preparation, extracted from Escherichia coli DH5alpha cells, was immobilized within a polyurethane foam matrix during polymer synthesis. The enzyme-foam interaction was shown to be covalent and analysis of the hydrolysis of paraoxon in aqueous solution demonstrated that more than 50% of the initial enzyme specific activity was retained after immobilization in the foam. Factors affecting the rate of paraoxon degradation include foam hydrophobicity, the degree of mixing applied to initiate polymerization, and foam pretreatment prior to use in substrate hydrolysis. The storage stability of the foam is significant, with phosphotriesterase-foam activity profiles exhibiting a three month half-life. Foams are currently being developed for biocatalytic air filtering, in which gaseous substrates will be simultaneously adsorbed and degraded by the immobilized enzyme system. (c) 1996 John Wiley & Sons, Inc.     

Effects of hemicastration and castration on foam production and its relationship with fertility in male Japanese quail

Healthy heavy body weight strain of adult male Japanese quail (Coturnix coturnix Japonica) of the same age were used in this study to observe the effect of hemicastration and castration on the frequency of foam discharges from cloacal gland and other related parameters. The quails were housed in individual cages and divided into four groups: control (intact birds), sham-operated control (intact birds with incision), hemicastrated, and castrated groups of birds. Hemicastration and castration were carried out surgically at 10 and 13 weeks of age, respectively. Subsequently, 3 weeks after castration birds were examined for different parameters. Hemicastration caused a significant (P < 0.05) drop in the foam discharge frequency, weight of the foam, and the level of testosterone in the plasma, whereas in castrated group these variables were observed nil or negligible as compared to both of the controls. A suppressive effect of hemicastration was also noticed on the body weight, area of the cloacal gland, as well as percent fertility. Castration induced the drastic regression of the cloacal gland and a significant reduction (P < 0.05) of the body weight was also noted as compared to other groups. Frequencies of foam discharges were twice the number in daytime (06:00-18:00 h) than night, irrespective of the groups. In another study, the effect of characteristics of foam or foam glands on fertility was examined in 77 male birds paired with females. Several characteristics of foam and foam glands were examined for infertility, such as light yellow foam, dark yellow foam, smaller area of foam gland (below 225 mm2), hardness of foam gland and certain unknown factors that contributed 0.23, 0.68, 5.23, 2.27 and 3.64% infertility, respectively. An overall 12.1% birds were found to be infertile. This data indicated that smaller sizes of foam glands might reflect the poorest fertilizing ability of the male birds. From this study, it may be concluded that the cloacal gland may be considered as an external indicator of testicular function of the birds. Characteristics of the cloacal gland or foam or both may be used as a simple and effective tool to predict the fertilizing ability of an individual male in view of the very small semen ejaculate that is very difficult to collect and evaluate for fertility.     

Phenotype determination of anti-GM3 positive cells in atherosclerotic lesions of the human aorta: Hypothetical role of ganglioside GM3 in foam cell formation

Earlier we reported that atherosclerotic plaques contain cells which were specifically and very intensively stained with anti-GM3 antibodies although no GM3 positive cells were detected in the normal non-diseased arterial intima. Because of their lipid inclusions, GM3 positive cells in atherosclerotic lesions seemed to be foam cells but their origin needed clarification. Using an immunohistochemical technique in the present work, we showed that some of these foam cells contained CD68 antigen. However, the most intense accumulation of GM3 occurred in the areas composed of foam cells which did not stain with any cell type-specific antibodies, including antibodies to macrophages (anti-CD68) and smooth muscle cells (anti-smooth muscle α-actin), perhaps, because the cell type-specific antigens were lost during the transformation of intimal cells into foam cells. Ultrastructural analysis of the areas where foam cells overexpressed GM3 demonstrated that some foam cells lacked both a basal membrane and myofilaments but contained a large number of secondary lysosomes and phagolysosomes, morphological features which might indicate their macrophage origin. Other foam cells contained a few myofilaments and fragments of basal membrane around their plasmalemmal membrane, suggesting a smooth muscle cell origin. These observations indicate that accumulation of excessive amounts of GM3 occurs in different cell types transforming into foam cells. We suggest that up-regulation of GM3 synthesis in intimal cells might be an essential event in foam cell formation. Shedding of a large number of membrane-bound microvesicles from the cell surface of foam cells was observed in areas of atherosclerotic lesions corresponding to extracellular GM3 accumulation. We speculate that extracellularly localised GM3 might affect the differentiation and modification of intimal cells in atherosclerotic lesions.