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Fulltext Energy absorption and morphological characteristics of opened-cell green rubber foam at different recycled carbon fiber loading

Mazliah, M., Noraiham, M., Anisah, A.L., Azrul, Y., Hairul, E.A.M., Jeefferie, A.R., et al.

Malaysian Journal of Microscopy, 2015;11(1):56-60.
MyJurnal

Incineration and disposal of carbon fiber waste from the aircraft industry lead to serious energy consumption and environmental pollution. The use of this waste as reinforcement is a wise approach to appreciate the high performance of the carbon fiber. This study is part of our effort to develop new green rubber foam from recycled carbon fiber prepreg (rCFP) reinforced natural rubber via internal mixer. It is focusing on the effect of different rCFP loading at 1, 3, 5, and 7 parts per hundred rubbers (phr) as reinforcement. The samples were prepared by melt compounding using an internal mixer and expanded via two step heat transfer foaming process. The physical properties of the green rubber foam were characterized and the results were observed to systematically correlate with the impact properties of the foam. The absorbed energy of the foam increases up to 0.3 joules with increasing relative foam density of 0.81 which is associated with the formation of smaller foam cells ~0.68mm and more spherical shape pores.

Matched MeSH terms: Foam Cells
Aggressive angiomyxoma of the vulva with an unusual vascular finding

Cheah PL, Looi LM, Sivanesaratnam V

Pathology, 1993 Jul;25(3):250-2.
PMID: 8265242

We report the first documented Malaysian case of aggressive angiomyxoma (AAM) of the vulva. A 56-yr-old woman of Indian ethnic origin presented with a vulval lesion which was clinically mistaken for a Bartholin's cyst. The lesion was surgically excised and a diagnosis of AAM was made histologically. Of particular interest was the finding of foamy and mononuclear inflammatory cells and fibrin in the walls of most of the lesional blood vessels. The patient recovered uneventfully and remains without tumor recurrence at the time of writing 37 mths after initial presentation.

Matched MeSH terms: Foam Cells/pathology
Fulltext Oxidative Stress in Cardiovascular Diseases: Involvement of Nrf2 Antioxidant Redox Signaling in Macrophage Foam Cells Formation

Ooi BK, Goh BH, Yap WH

Int J Mol Sci, 2017 Nov 05;18(11).
PMID: 29113088 DOI: 10.3390/ijms18112336

Oxidative stress is an important risk factor contributing to the pathogenesis of cardiovascular diseases. Oxidative stress that results from excessive reactive oxygen species (ROS) production accounts for impaired endothelial function, a process which promotes atherosclerotic lesion or fatty streaks formation (foam cells). Nuclear factor erythroid 2-related factor 2 (Nrf2) is a transcription factor involved in cellular redox homeostasis. Upon exposure to oxidative stress, Nrf2 is dissociated from its inhibitor Keap-1 and translocated into the nucleus, where it results in the transcriptional activation of cell defense genes. Nrf2 has been demonstrated to be involved in the protection against foam cells formation by regulating the expression of antioxidant proteins (HO-1, Prxs, and GPx1), ATP-binding cassette (ABC) efflux transporters (ABCA1 and ABCG1) and scavenger receptors (scavenger receptor class B (CD36), scavenger receptor class A (SR-A) and lectin-type oxidized LDL receptor (LOX-1)). However, Nrf2 has also been reported to exhibit pro-atherogenic effects. A better understanding on the mechanism of Nrf2 in oxidative stress-induced cardiac injury, as well as the regulation of cholesterol uptake and efflux, are required before it can serve as a novel therapeutic target for cardiovascular diseases prevention and treatment.

Matched MeSH terms: Foam Cells/metabolism*
Maslinic acid modulates secreted phospholipase A2-IIA (sPLA2-IIA)-mediated inflammatory effects in macrophage foam cells formation

Yap WH, Ooi BK, Ahmed N, Lim YM

J Biosci, 2018 Jun;43(2):277-285.
PMID: 29872016

Secretory phospholipase A2-IIA (sPLA2-IIA) is one of the key enzymes causing lipoprotein modification and vascular inflammation. Maslinic acid is a pentacyclic triterpene which has potential cardioprotective and anti-inflammatory properties. Recent research showed that maslinic acid interacts with sPLA2-IIA and inhibits sPLA2-IIA-mediated monocyte differentiation and migration. This study elucidates the potential of maslinic acid in modulating sPLA2-IIA-mediated inflammatory effects in THP-1 macrophages. We showed that maslinic acid inhibits sPLA2-IIA-mediated LDL modification and suppressed foam cell formation. Further analysis revealed that sPLA2-IIA only induced modest LDL oxidation and that inhibitory effect of maslinic acid on sPLA2-IIA-mediated foam cells formation occurred independently of its anti-oxidative properties. Interestingly, maslinic acid was also found to significantly reduce lipid accumulation observed in macrophages treated with sPLA2-IIA only. Flow cytometry analysis demonstrated that the effect observed in maslinic acid might be contributed in part by suppressing sPLA2-IIA-induced endocytic activity, thereby inhibiting LDL uptake. The study further showed that maslinic acid suppresses sPLA2-IIA-induced up-regulation of PGE2 levels while having no effects on COX-2 activity. Other pro-inflammatory mediators TNF-a and IL-6 were not induced in sPLA2-IIA-treated THP-1 macrophages. The findings of this study showed that maslinic acid inhibit inflammatory effects induced by sPLA2-IIA, including foam cells formation and PGE2 production.

Matched MeSH terms: Foam Cells/drug effects; Foam Cells/pathology
IL-17A induction of ADAMTS-5 in differentiated THP-1 cells is modulated by the ERK signaling pathway

Thou EMH, Choo QC, Chew CH

Eur. Cytokine Netw., 2020 Jun 01;31(2):59-67.
PMID: 32933893 DOI: 10.1684/ecn.2020.0446

Atherosclerosis is initiated when lipoproteins are trapped by proteoglycans in the arterial intima. Macrophages play a vital role in this disease, especially in the formation of foam cells and the regulation of pro-inflammatory responses. They also participate in plaque stabilization through the secretion of matrix metalloproteinases. Studies have reported the role of ADAMTS proteases in osteoarthritis and atherosclerotic lesions.In the present study, we have studied the effect of interleukin-17A (IL-17A) on the expression of ADAMTS-5 in the macrophage cell line THP-1. The results show that the mRNA and protein expression levels of ADAMTS-5 were significantly upregulated when differentiated THP-1 cells were treated with 100 ng/mL of IL-17A for 24 h with maximum ADAMTS-5 mRNA expression levels obtained at 8 h of stimulation. Subsequent inhibition studies showed that IL-17A upregulation of ADAMTS-5 was mediated through ERK and JNK pathways in THP-1 cells. Phosphorylation studies revealed that the expression of ADAMTS-5 transcripts was upregulated by IL-17A through the activation of p-c-Raf (S338), p-MEK1/2 (Ser217/221), p-p44/42 MAPK (Thr202/Tyr204), and p-Elk1 (Ser383). ERK1/2 siRNA transfection further confirmed that the ERK pathway is involved in the expression of ADAMTS-5 in IL-17A-stimulated THP-1 cells.

Matched MeSH terms: Foam Cells
Maslinic acid suppresses macrophage foam cells formation: Regulation of monocyte recruitment and macrophage lipids homeostasis

Phang SW, Ooi BK, Ahemad N, Yap WH

Vascul. Pharmacol., 2020 03 19;128-129:106675.
PMID: 32200116 DOI: 10.1016/j.vph.2020.106675

The transformation of macrophages to foam cells is a critical component in atherosclerotic lesion formation. Maslinic acid (MA), a novel natural pentacyclic triterpene, has cardioprotective and anti-inflammatory properties. It is hypothesized that MA can suppress monocyte recruitment to endothelial cells and inhibit macrophage foam cells formation. Previous study shows that MA inhibits inflammatory effects induced by sPLA2-IIA, including foam cells formation. This study elucidates the regulatory effect of MA in monocyte recruitment, macrophage lipid accumulation and cholesterol efflux. Our findings demonstrate that MA inhibits THP-1 monocyte adhesion to HUVEC cells in a TNFα-dependent and independent manner, but it induces trans-endothelial migration marginally at low concentration. MA down-regulates both gene and protein expression on VCAM-1 and MCP-1 in HUVECs. We further showed that MA suppresses macrophage foam cells formation, as indicated from the Oil-Red-O staining and flow cytometric analysis of intracellular lipids accumulation. The effects observed may be attributed to the antioxidant properties of MA where it was shown to suppress CuSO4-induced lipid peroxidation. MA inhibits scavenger receptors SR-A and CD36 expression while enhancing cholesterol efflux. MA enhances cholesterol efflux transporters ABCA1 and ABCG1 genes expression marginally without inducing its protein expression. In this study, MA was shown to target important steps that contribute to foam cell formation, including its ability in reducing monocytes adhesion to endothelial cells and LDL peroxidation, down-regulating scavenger receptors expression as well as enhancing cholesterol efflux, which might be of great importance in the context of atherosclerosis prevention and treatment.

Matched MeSH terms: Foam Cells
Gynura procumbens ethanol extract and its fractions inhibit macrophage derived foam cell formation

Manogaran M, Vuanghao L, Mohamed R

J Ethnopharmacol, 2020 Mar 01;249:112410.
PMID: 31747560 DOI: 10.1016/j.jep.2019.112410

ETHNOPHARMACOLOGY RELEVANCE: Gynura procumbens (Lour.) Merr. displayed cardio-protective effect that may prevent atherogenesis. The primary underlying pathological process of cardiovascular disease is atherosclerosis. Atherosclerotic lesion composed of macrophages, T cells and other immune cells which incorporated with cholesterol that infiltrates from the blood.
AIM OF THE STUDY: The present study was performed to determine underlying mechanism of G. procumbens ethanol extract and its fractions such as aqueous, chloroform, ethyl acetate and hexane affect macrophage derived foam cell formation.
MATERIALS AND METHODS: Lipid droplets accumulation in treated macrophages were visualized by Oil Red O staining while the total cholesterol present in the treated macrophages were measured using Cholestryl Ester quantification assay kit. Enzyme-Linked Immunosorbent Assay (ELISA) were used to detect TNF-α and IL-1β secretion in the supernatant of treated macrophages. Gene expression of Lectin-like oxidized low-density lipoprotein receptor-1 (LOX-1) and ATP-binding cassette transporter A-1 (ABCA-1) in treated macrophages were analyzed using Real-Time Quantitative Polymerase Chain Reaction (RT-qPCR).
RESULTS: G. procumbens ethanol extract and its fractions reduced lipid droplet accumulation and total cholesterol in oxLDL-treated macrophages together with significantly reduction of TNF-α and IL-1β secretions in supernatant oxLDL-treated macrophages. LOX-1 gene expression was significantly reduced when G. procumbens ethanol extract and its fractions were added in oxDL-treated macrophages. In contrast, G. procumbens ethanol extract and its fractions significantly increased the expression of ABCA-1 gene in oxLDL-treated macrophages.
CONCLUSION: In conclusion, G. procumbens ethanol extract and its fractions inhibit the formation of macrophage derived foam cell by reducing TNF-α and IL-1β expression, which usually highly expressed in atherosclerotic plaques, suppressing scavenger receptor LOX-1 gene that binds oxLDL but induced ABCA-1 gene that mediate lipid efflux from macrophages.

Matched MeSH terms: Foam Cells/drug effects*; Foam Cells/metabolism
Effect of methanolic extract of Piper sarmentosum leaves on neointimal foam cell infiltration in rabbits fed with high cholesterol diet

Amran AA, Zakaria Z, Othman F, Das S, Al-Mekhlafi HM, Raj S, et al.

EXCLI J, 2012;11:274-83.
PMID: 27366140

Previous research has shown the beneficial effects of aqueous extract of Piper sarmentosum (P.s) on atherosclerosis. The first stage in atherosclerosis is the formation of foam cell. The aim of this study was to investigate the effect of the methanol extract of P.s on fatty streaks by calculating neointimal foam cell infiltration in rabbits fed with high cholesterol diet. Thirty six male New Zealand white rabbits were divided equally into six groups: (i) C: control group fed normal rabbit chow; (ii) CH: cholesterol diet (1 % cholesterol); (iii) PM1: 1 % cholesterol with methanol extract of P.s (62.5 mg/kg); (iv) PM2: 1 % cholesterol with methanol extract of P.s (125 mg/kg); (v) PM3: 1 % cholesterol with methanol extract of P.s (250 mg/kg); (vi) SMV group fed 1 % cholesterol supplemented with Simvistatin drug (1.2 mg/kg). All animals were treated for 10 weeks. At the end of the treatment, the rabbits were fasted and sacrificed and the aortic tissues were collected for histological studies to measure the area of the neointimal foam cell infiltration using software. The thickening of intima ratio of atherosclerosis and morphological changes by scanning electron microscope were measured. The results showed that the atherosclerotic group had significantly bigger area of fatty streak compared to the control group. The area of fatty streak in the abdominal aorta was significantly reduced in the treatment groups which were similar with the SMV group. Similarly, there was a reduction in the number of foam cell in the treatment groups compared to the atherosclerotic group as seen under scanning microscope. In conclusion, histological study demonstrated that the methanol extract of the P.s could reduce the neointimal foam cell infiltration in the lumen of the aorta and the atherosclerotic lesion.

Matched MeSH terms: Foam Cells
Omega-3 fatty acids and leukocyte-endothelium adhesion: Novel anti-atherosclerotic actions

Baker EJ, Yusof MH, Yaqoob P, Miles EA, Calder PC

Mol Aspects Med, 2018 12;64:169-181.
PMID: 30102930 DOI: 10.1016/j.mam.2018.08.002

Endothelial cells (ECs) play a role in the optimal function of blood vessels. When endothelial function becomes dysregulated, the risk of developing atherosclerosis increases. Specifically, upregulation of adhesion molecule expression on ECs promotes the movement of leukocytes, particularly monocytes, into the vessel wall. Here, monocytes differentiate into macrophages and may become foam cells, contributing to the initiation and progression of an atherosclerotic plaque. The ability of omega-3 (n-3) polyunsaturated fatty acids (PUFAs) to influence the expression of adhesion molecules by ECs and to modulate leukocyte-endothelial adhesion has been studied in cell culture using various types of ECs, in animal feeding studies and in human trials; the latter have tended to evaluate soluble forms of adhesion molecules that circulate in the bloodstream. These studies indicate that n-3 PUFAs (both eicosapentaenoic acid and docosahexaenoic acid) can decrease the expression of key adhesion molecules, such as vascular cell adhesion molecule 1, by ECs and that this results in decreased adhesive interactions between leukocytes and ECs. These findings suggest that n-3 PUFAs may lower leukocyte infiltration into the vascular wall, which could contribute to reduced atherosclerosis and lowered risk of cardiovascular disease.

Matched MeSH terms: Foam Cells
Fulltext Aqueous extract of Piper sarmentosum decreases atherosclerotic lesions in high cholesterolemic experimental rabbits

Amran AA, Zakaria Z, Othman F, Das S, Raj S, Nordin NA

Lipids Health Dis, 2010 Apr 30;9:44.
PMID: 20433693 DOI: 10.1186/1476-511X-9-44

BACKGROUND: Piper sarmentosum (P.s) has flavonoid component in its leaves which has antioxidative effect. To date, its effect on atherosclerosis has not been studied histologically.
AIM: The study aimed to investigate the effect of P.s on atherosclerotic changes in hypercholesterolemic rabbits.
METHODS: Forty two male New Zealand white rabbits were divided into seven groups. C - control group fed normal rabbit chow, CH - cholesterol diet (1% cholesterol), W1 - 1% cholesterol with water extract of P.s (62.5 mg/kg), W2 - 1% cholesterol with water extract of P.s (125 mg/kg), W3 - 1% cholesterol with water extract of P.s (250 mg/kg), W4 - 1% cholesterol with water extract of P.s (500 mg/kg) and Smv - 1% cholesterol supplemented with simvistatin drug (1.2 mg/kg). All rabbits were treated for 10 weeks. Following 10 weeks of supplementation, the animals were sacrificed and the aortic tissue was taken for histological study.
RESULTS: Rabbits fed only with high cholesterol diet 1% cholesterol (CH) showed focal fatty streak lesions compared to the C group and 1% cholesterol supplemented with simvistatin drug (Smv) group. Atherosclerotic lesions in the 1% cholesterol group supplemented with P.s (500 mg/kg) i.e. W4 group showed significant reduction (30 + or - 6.0%, p < 0.05) in fatty streak compared to the high cholesterol group (85.6 + or - 4.1%) under Sudan IV stain. The atherosclerotic lesions under transmission electron microscope showed reduction in foam cells in the treatment groups compared to the CH groups.
CONCLUSION: Administration of P.s extract has protective effect against atheroscleros.

Matched MeSH terms: Foam Cells

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