Displaying publications 81 - 100 of 377 in total

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  1. Ugusman A, Zakaria Z, Hui CK, Nordin NA
    Clinics (Sao Paulo), 2010 Jul;65(7):709-14.
    PMID: 20668629 DOI: 10.1590/S1807-59322010000700010
    Nitric oxide produced by endothelial nitric oxide synthase (eNOS) possesses multiple anti-atherosclerotic properties. Hence, enhanced expression of eNOS and increased Nitric oxide levels may protect against the development of atherosclerosis. Piper sarmentosum is a tropical plant with antioxidant and anti-inflammatory activities. This study aimed to investigate the effects of Piper sarmentosum on the eNOS and Nitric oxide pathway in cultured human umbilical vein endothelial cells (HUVECs).
    Matched MeSH terms: Nitric Oxide/biosynthesis*; Nitric Oxide Synthase Type III/physiology*
  2. Jaarin K, Mustafa MR, Leong XF
    Clinics (Sao Paulo), 2011;66(12):2125-32.
    PMID: 22189740
    OBJECTIVES: The goal of this study was to determine the possible mechanism that is involved in the blood pressure-raising effect of heated vegetable oils.

    METHODS: Adult male Sprague-Dawley rats were divided into 11 groups; the control group was fed with rat chow, and the other groups were fed with chow that was mixed with 15% weight/weight palm or soy oils, which were either in a fresh form or heated once, twice, five, or ten times. Blood pressures were measured at the baseline and throughout the 24-week study. Plasma nitric oxide levels were assessed prior to treatment and at the end of the study. Following 24 weeks, the rats were sacrificed to investigate their vascular reactivity using the thoracic aorta.

    RESULTS: Palm and soy oils had no detrimental effects on blood pressure, and they significantly elevated the nitric oxide contents and reduced the contractile responses to phenylephrine. However, trials using palm and soy oils that were repeatedly heated showed an increase in blood pressure, enhanced phenylephrine-induced contractions, reduced acetylcholine- and sodium nitroprusside-induced relaxations relative to the control and rats that were fed fresh vegetable oils.

    CONCLUSIONS: The blood pressure-raising effect of the heated vegetable cooking oils is associated with increased vascular reactivity and a reduction in nitric oxide levels. The chronic consumption of heated vegetable oils leads to disturbances in endogenous vascular regulatory substances, such as nitric oxide. The thermal oxidation of the cooking oils promotes the generation of free radicals and may play an important contributory role in the pathogenesis of hypertension in rats.

    Matched MeSH terms: Nitric Oxide/analysis
  3. Jaarin K, Foong WD, Yeoh MH, Kamarul ZY, Qodriyah HM, Azman A, et al.
    Clinics (Sao Paulo), 2015 Nov;70(11):751-7.
    PMID: 26602523 DOI: 10.6061/clinics/2015(11)07
    This study was conducted to determine whether the blood pressure-lowering effect of Nigella sativa might be mediated by its effects on nitric oxide, angiotensin-converting enzyme, heme oxygenase and oxidative stress markers.
    Matched MeSH terms: Nitric Oxide/blood
  4. Zengin G, Rodrigues MJ, Abdallah HH, Custodio L, Stefanucci A, Aumeeruddy MZ, et al.
    Comput Biol Chem, 2018 Dec;77:178-186.
    PMID: 30336375 DOI: 10.1016/j.compbiolchem.2018.10.005
    The genus Silene is renowned in Turkey for its traditional use as food and medicine. Currently, there are 138 species of Silene in Turkey, amongst which have been several studies for possible pharmacological potential and application in food industry. However, there is currently a paucity of data on Silene salsuginea Hub.-Mor. This study endeavours to access its antioxidant, enzyme inhibitory, and anti-inflammatory properties. Besides, reversed-phase high-performance liquid chromatography-diode array detector (RP-HPLC-DAD) was used to detect phenolic compounds, and molecular docking was performed to provide new insights for tested enzymes and phenolics. High amounts of apigenin (534 μg/g extract), ferulic acid (452 μg/g extract), p-coumaric acid (408 μg/g extract), and quercetin (336 μg/g extract) were detected in the methanol extract while rutin (506 μg/g extract) was most abundant in the aqueous extract. As for their biological properties, the methanol extract exhibited the best antioxidant effect in the DPPH and CUPRAC assays, and also the highest inhibition against tyrosinase. The aqueous extract was the least active enzyme inhibitor but showed the highest antioxidant efficacy in the ABTS, FRAP, and metal chelating assays. At a concentration of 15.6 μg/mL, the methanol extract resulted in a moderate decrease (25.1%) of NO production in lipopolysaccharide-stimulated cells. Among the phenolic compounds, epicatechin, (+)-catechin, and kaempferol showed the highest binding affinity towards the studied enzymes in silico. It can be concluded that extracts of S. salsuginea are a potential source of functional food ingredients but need further analytical experiments to explore its complexity of chemical compounds and pharmacological properties as well as using in vivo toxicity models to establish its maximum tolerated dose.
    Matched MeSH terms: Nitric Oxide/analysis; Nitric Oxide/antagonists & inhibitors; Nitric Oxide/biosynthesis
  5. Thent ZC, Chakraborty C, Mahakkanukrauh P, Nik Ritza Kosai Nik Mahmood N, Rajan R, Das S
    Curr Drug Targets, 2017;18(11):1250-1258.
    PMID: 27138760 DOI: 10.2174/1389450117666160502151600
    BACKGROUND: Recently, there are scientific attempts to discover new drugs in the biotechnology industry in order to treat various diseases including atherosclerosis.

    OBJECTIVE: The main objective of the present review was to highlight the cellular, molecular biology and inflammatory process related to the atheromatous plaques.

    METHODS: A thorough literature search of Pubmed, Google and Scopus databases was done.

    RESULTS: Atherosclerosis is considered to be a leading cause of death throughout the world. Atherosclerosis involves oxidative damage to the cells with production of reactive oxygen species (ROS). Development of atheromatous plaques in the arterial wall is a common feature. Specific inflammatory markers pertaining to the arterial wall in atherosclerosis may be useful for both diagnosis and treatment. These include Nitric oxide (NO), cytokines, macrophage inhibiting factor (MIF), leucocytes and Pselectin. Modern therapeutic paradigms involving endothelial progenitor cells therapy, angiotensin II type-2 (AT<sub>2</sub>R) and ATP-activated purinergic receptor therapy are notable to mention.

    CONCLUSION: Future drugs may be designed aiming three signalling mechanisms of AT<sub>2</sub>R which are (a) activation of protein phosphatases resulting in protein dephosphorylation (b) activation of bradykinin/nitric oxide/cyclic guanosine 3&#039;,5&#039;-monophosphate pathway by vasodilation and (c) stimulation of phospholipase A(2) and release of arachidonic acid. Drugs may also be designed to act on ATP-activated purinergic receptor channel type P2X7 molecules which acts on cardiovascular system.

    Matched MeSH terms: Nitric Oxide/metabolism
  6. Nor Arfuzir NN, Agarwal R, Iezhitsa I, Agarwal P, Sidek S, Spasov A, et al.
    Curr Eye Res, 2018 08;43(8):1032-1040.
    PMID: 29676937 DOI: 10.1080/02713683.2018.1467933
    PURPOSE: Retinal ganglion cell apoptosis in glaucoma is associated with elevated levels of endothelin-1 (ET1), a potent vasoconstrictor. ET1-induced retinal ischemia leads to altered expression of nitric oxide synthase (NOS) isoforms leading to increased formation of nitric oxide (NO) and retinal nitrosative stress. Since magnesium (Mg) is known to improve endothelial functions and reduce oxidative stress and taurine (TAU) possesses potent antioxidant properties, we investigated the protective effects of magnesium acetyltaurate (MgAT) against ET1-induced nitrosative stress and retinal damage in rats. We also compared the effects of MgAT with that of TAU alone.

    METHODS: Sprague Dawley rats were intravitreally injected with ET1. MgAT and TAU were administered as pre-, co-, or posttreatment. Subsequently, the expression of NOS isoforms was detected in retina by immunohistochemistry, retinal nitrotyrosine level was estimated using ELISA, and retinal cell apoptosis was detected by TUNEL staining.

    RESULTS: Intravitreal ET1 caused a significant increase in the expressions of nNOS and iNOS while eNOS expression was significantly reduced compared to vehicle treated group. Administration of both MgAT and TAU restored the altered levels of NOS isoform expression, reduced retinal nitrosative stress and retinal cell apoptosis. The effect of MgAT, however, was greater than that of TAU alone.

    CONCLUSIONS: MgAT and TAU prevent ET1-induced retinal cell apoptosis by reducing retinal nitrosative stress in Sprague Dawley rats. Addition of TAU to Mg seems to enhance the efficacy of TAU compared to when given alone. Moreover, the pretreatment with MgAT/TAU showed higher efficacy compared to co- or posttreatment.

    Matched MeSH terms: Nitric Oxide Synthase Type II/biosynthesis; Nitric Oxide Synthase Type I/biosynthesis
  7. Ahmad N, Shah SA, Abdul Gafor AH, Abdul Murad NA, Kamaruddin MA, Abd Jalal N, et al.
    Diabet Med, 2020 11;37(11):1890-1901.
    PMID: 32012348 DOI: 10.1111/dme.14257
    AIM: To examine the possible gene-environment interactions between 32 single nucleotide polymorphisms and environmental factors that could modify the probability of chronic kidney disease.

    METHODS: A case-control study was conducted involving 600 people with type 2 diabetes (300 chronic kidney disease cases, 300 controls) who participated in The Malaysian Cohort project. Retrospective subanalysis was performed on the chronic kidney disease cases to assess chronic kidney disease progression from the recruitment phase. We genotyped 32 single nucleotide polymorphisms using mass spectrometry. The probability of chronic kidney disease and predicted rate of newly detected chronic kidney disease progression were estimated from the significant gene-environment interaction analyses.

    RESULTS: Four single nucleotide polymorphisms (eNOS rs2070744, PPARGC1A rs8192678, KCNQ1 rs2237895 and KCNQ1 rs2283228) and five environmental factors (age, sex, smoking, waist circumference and HDL) were significantly associated with chronic kidney disease. Gene-environment interaction analyses revealed significant probabilities of chronic kidney disease for sex (PPARGC1A rs8192678), smoking (eNOS rs2070744, PPARGC1A rs8192678 and KCNQ1 rs2237895), waist circumference (eNOS rs2070744, PPARGC1A rs8192678, KCNQ1 rs2237895 and KCNQ1 rs2283228) and HDL (eNOS rs2070744 and PPARGC1A rs8192678). Subanalysis indicated that the rate of newly detected chronic kidney disease progression was 133 cases per 1000 person-years (95% CI: 115, 153), with a mean follow-up period of 4.78 (SD 0.73) years. There was a significant predicted rate of newly detected chronic kidney disease progression in gene-environment interactions between KCNQ1 rs2283228 and two environmental factors (sex and BMI).

    CONCLUSIONS: Our findings suggest that the gene-environment interactions of eNOS rs2070744, PPARGC1A rs8192678, KCNQ1 rs2237895 and KCNQ1 rs2283228 with specific environmental factors could modify the probability for chronic kidney disease.

    Matched MeSH terms: Nitric Oxide Synthase Type III/genetics*
  8. Swamy M, Sirajudeen KN, Chandran G
    Drug Chem Toxicol, 2009;32(4):326-31.
    PMID: 19793024 DOI: 10.1080/01480540903130641
    Neuronal excitation, involving the excitatory glutamate receptors, is recognized as an important underlying mechanism in neurodegenerative disorders. To understand their role in excitotoxicity, the nitric oxide synthase (NOS), argininosuccinate synthetase (AS), argininosuccinate lyase (AL), glutamine synthetase (GS), and arginase activities, along with the concentration of nitrate/nitrite, thiobarbituric acid-reactive substances (TBARS), and total antioxidant status (TAS), were estimated in the cerebral cortex, cerebellum, and brain stem of rats subjected to kainic acid-mediated excitotoxicity. The results of this study clearly demonstrated the increased production of NO by increased activity of NOS. The increased activities of AS and AL suggest the increased and effective recycling of citrulline to arginine in excitotoxicity, making NO production more effective and contributing to its toxic effects. The decreased activity of GS may favor the prolonged availability of glutamic acid, causing excitotoxicity, leading to neuronal damage. The increased formation of TBARS and decreased TAS indicate the presence of oxidative stress in excitotoxicity.
    Matched MeSH terms: Nitric Oxide/metabolism*; Nitric Oxide Synthase/metabolism*
  9. Kanwar JR, Samarasinghe RM, Kumar K, Arya R, Sharma S, Zhou SF, et al.
    Drug Des Devel Ther, 2015;9:2927-40.
    PMID: 26089642 DOI: 10.2147/DDDT.S77369
    INTRODUCTION: Inflammatory mediators are key players in the pathogenesis of osteoarthritis (OA) and bone destruction. Conventional drugs suppress symptomatic activity and have no therapeutic influence on disease. Cissus quadrangularis and Withania somnifera are widely used for the treatment of bone fractures and wounds; however, the cellular and molecular mechanisms regulated by these herbals are still unclear.

    METHODS: We established an in vitro OA culture model by exposing human chondrocytes to proinflammatory cytokine and interleukin (IL)-1β for 36 hours prior to treatment with the herbals: C. quadrangularis, W. somnifera, and the combination of the two herbals. Cell viability, toxicity, and gene expression of OA modifying agents were examined. In addition, expression of survivin, which is crucial for cell growth, was analyzed. In vivo work on osteotomized rats studied the bone and cartilage regenerative effects of C. quadrangularis, W. somnifera, and the combination therapy.

    RESULTS: Exposure of chondrocytes to IL-1β induced significant toxicity and cell death. However, herbal treatment alleviated IL-1β induced cell toxicity and upregulated cell growth and proliferation. C. quadrangularis inhibited gene expression of cytokines and matrix metalloproteinases, known to aggravate cartilage and bone destruction, and augmented expression of survivin by inhibiting p38 MAPK. Interestingly, osteotomized rats treated with C. quadrangularis drastically enhanced alkaline phosphatase and cartilage tissue formation as compared to untreated, W. somnifera only, or the combination of both herbals.

    CONCLUSION: Our findings demonstrate for the first time the signaling mechanisms regulated by C. quadrangularis and W. somnifera in OA and osteogenesis. We suggest that the chondroprotective effects and regenerative ability of these herbals are via the upregulation of survivin that exerts inhibitory effects on the p38 MAPK signaling pathway. These findings thus validate C. quadrangularis as a potential therapeutic for rheumatic disorders.

    Matched MeSH terms: Nitric Oxide/metabolism
  10. Yuandani, Jantan I, Ilangkovan M, Husain K, Chan KM
    Drug Des Devel Ther, 2016;10:1935-45.
    PMID: 27354767 DOI: 10.2147/DDDT.S105651
    Standardized extract of Phyllanthus amarus has previously been shown to have a strong inhibitory effect on phagocytic activity of human neutrophils. The current study was carried out to evaluate the effects of constituents of the extract of P. amarus on nitric oxide (NO) production as well as lymphocyte proliferation and cytokine release from phagocytes. Three compounds, ethyl 8-hydroxy-8-methyl-tridecanoate, 7β,19α dihydroxy-urs-12-ene, and 1,7,8-trihydroxy-2-naphtaldehyde, together with seven known compounds were isolated from the whole plant of P. amarus. The isolated compounds and reference standards, ie, gallic acid, ellagic acid, corilagin, and geraniin, which were quantitatively analyzed in the extracts, were evaluated for their effects on immune cells. Among the compounds tested, the lignans, especially phyltetralin and phyllanthin, showed strong inhibition on lymphocyte proliferation with half maximal inhibitory concentration (IC50) values of 1.07 μM and 1.82 μM, respectively. Ethyl 8-hydroxy-8-methyl-tridecanoate and 1,7,8-trihydroxy-2-naphtaldehyde exhibited strong inhibition on nitric oxide production with IC50 values of 0.91 μM and 1.07 μM, respectively. Of all the compounds, corilagin was the strongest inhibitor of tumor necrosis factor-α release with an IC50 value of 7.39 μM, whereas geraniin depicted the strongest inhibitory activity on interleukin-1β release with an IC50 value of 16.41 μM. The compounds constituting the extract of P. amarus were able to inhibit the innate immune response of phagocytes at different steps.
    Matched MeSH terms: Nitric Oxide/chemistry*
  11. Iman V, Mohan S, Abdelwahab SI, Karimian H, Nordin N, Fadaeinasab M, et al.
    Drug Des Devel Ther, 2017;11:103-121.
    PMID: 28096658 DOI: 10.2147/DDDT.S115135
    Therapy that directly targets apoptosis and/or inflammation could be highly effective for the treatment of cancer. Murraya koenigii is an edible herb that has been traditionally used for cancer treatment as well as inflammation. Here, we describe that girinimbine, a carbazole alkaloid isolated from M. koenigii, induced apoptosis and inhibited inflammation in vitro as well as in vivo. Induction of apoptosis in human colon cancer cells (HT-29) by girinimbine revealed decreased cell viability in HT-29, whereas there was no cytotoxic effect on normal colon cells. Changes in mitochondrial membrane potential, nuclear condensation, cell permeability, and cytochrome c translocation in girinimbine-treated HT-29 cells demonstrated involvement of mitochondria in apoptosis. Early-phase apoptosis was shown in both acridine orange/propidium iodide and annexin V results. Girinimbine treatment also resulted in an induction of G0/G1 phase arrest which was further corroborated with the upregulation of two cyclin-dependent kinase proteins, p21 and p27. Girinimbine treatment activated apoptosis through the intrinsic pathway by activation of caspases 3 and 9 as well as cleaved caspases 3 and 9 which ended by triggering the execution pathway. Moreover, apoptosis was confirmed by downregulation of Bcl-2 and upregulation of Bax in girinimbine-treated cells. In addition, the key tumor suppressor protein, p53, was seen to be considerably upregulated upon girinimbine treatment. Induction of apoptosis by girinimbine was also evidenced in vivo in zebrafish embryos, with results demonstrating significant distribution of apoptotic cells in embryos after a 24-hour treatment period. Meanwhile, anti-inflammatory action was evidenced by the significant dose-dependent girinimbine inhibition of nitric oxide production in lipopolysaccharide/interferon-gamma-induced cells along with significant inhibition of nuclear factor-kappa B translocation from the cytoplasm to nucleus in stimulated RAW 264.7 cells. Girinimbine was also shown to have considerable antioxidant activity whereby 20 μg/mL of girinimbine was equivalent to 82.17±1.88 μM of Trolox. In mice with carrageenan-induced peritonitis, oral pretreatment with girinimbine helped limit total leukocyte migration (mainly of neutrophils), and reduced pro-inflammatory cytokine levels (interleukin-1beta and tumor necrosis factor-alpha) in the peritoneal fluid. These findings strongly suggest that girinimbine could act as a chemopreventive and/or chemotherapeutic agent by inducing apoptosis while suppressing inflammation. There is a potential for girinimbine to be further investigated for its applicability in treating early stages of cancer.
    Matched MeSH terms: Nitric Oxide/antagonists & inhibitors; Nitric Oxide/biosynthesis
  12. Adewoyin M, Mohsin SM, Arulselvan P, Hussein MZ, Fakurazi S
    Drug Des Devel Ther, 2015;9:2475-84.
    PMID: 25995619 DOI: 10.2147/DDDT.S72716
    BACKGROUND: Cinnamic acid (CA) is a phytochemical originally derived from Cinnamomum cassia, a plant with numerous pharmacological properties. The intercalation of CA with a nanocarrier, zinc layered hydroxide, produces cinnamate-zinc layered hydroxide (ZCA), which has been previously characterized. Intercalation is expected to improve the solubility and cell specificity of CA. The nanocarrier will also protect CA from degradation and sustain its release. The aim of this study was to assess the effect of intercalation on the anti-inflammatory capacity of CA.

    METHODS: In this study, the anti-inflammatory activity of ZCA was investigated and compared with that of nonintercalated CA. Evaluations were based on the capacity of ZCA and CA to modulate the release of nitric oxide, prostaglandin E2, interleukin (IL)-6, tumor necrosis factor alpha (TNF-α), IL-1β, and IL-10 in lipopolysaccharide-induced RAW 264.7 cells. Additionally, the expression of proinflammatory enzymes, ie, cyclooxygenase-2, inducible nitric oxide synthase, and nuclear factor kappa B (NF-κB), were examined.

    RESULTS: Although both ZCA and CA downregulated nitric oxide, prostaglandin E2, tumor necrosis factor alpha, IL-1β, and IL-6, ZCA clearly displayed better activity. Similarly, expression of cyclooxygenase-2 and inducible nitric oxide synthase were inhibited in samples treated with ZCA and CA. The two compounds effectively inactivated the transcription factor NF-κB, but the anti-inflammatory cytokine, IL-10, was significantly upregulated by ZCA only.

    CONCLUSION: The present findings suggest that ZCA possesses better anti-inflammatory potential than CA, while zinc layered hydroxide had little or no effect, and these results were comparable with the positive control.

    Matched MeSH terms: Nitric Oxide/biosynthesis
  13. Barber BE, Grigg MJ, Piera KA, William T, Cooper DJ, Plewes K, et al.
    Emerg Microbes Infect, 2018 Jun 06;7(1):106.
    PMID: 29872039 DOI: 10.1038/s41426-018-0105-2
    Plasmodium knowlesi occurs throughout Southeast Asia, and is the most common cause of human malaria in Malaysia. Severe disease in humans is characterised by high parasite biomass, reduced red blood cell deformability, endothelial activation and microvascular dysfunction. However, the roles of intravascular haemolysis and nitric oxide (NO)-dependent endothelial dysfunction, important features of severe falciparum malaria, have not been evaluated, nor their role in acute kidney injury (AKI). In hospitalised Malaysian adults with severe (n = 48) and non-severe (n = 154) knowlesi malaria, and in healthy controls (n = 50), we measured cell-free haemoglobin (CFHb) and assessed associations with the endothelial Weibel-Palade body (WPB) constituents, angiopoietin-2 and osteoprotegerin, endothelial and microvascular function, and other markers of disease severity. CFHb was increased in knowlesi malaria in proportion to disease severity, and to a greater extent than previously reported in severe falciparum malaria patients from the same study cohort. In knowlesi malaria, CFHb was associated with parasitaemia, and independently associated with angiopoietin-2 and osteoprotegerin. As with angiopoietin-2, osteoprotegerin was increased in proportion to disease severity, and independently associated with severity markers including creatinine, lactate, interleukin-6, endothelial cell adhesion molecules ICAM-1 and E-selectin, and impaired microvascular reactivity. Osteoprotegerin was also independently associated with NO-dependent endothelial dysfunction. AKI was found in 88% of those with severe knowlesi malaria. Angiopoietin-2 and osteoprotegerin were both independent risk factors for acute kidney injury. Our findings suggest that haemolysis-mediated endothelial activation and release of WPB constituents is likely a key contributor to end-organ dysfunction, including AKI, in severe knowlesi malaria.
    Matched MeSH terms: Nitric Oxide/metabolism
  14. Pang KL, Chin KY, Nirwana SI
    PMID: 36597600 DOI: 10.2174/1871530323666230103153134
    BACKGROUND: The immunomodulatory effects of plants have been utilised to enhance the immunity of humans against infections. However, evidence of such effects of agarwood leaves is very limited despite the long tradition of consuming the leaves as tea.

    OBJECTIVE: This study aimed to investigate the immuno-modulatory effects of agarwood leaf extract (ALE) derived from Aquilaria malaccensis using RAW264.7 murine macrophages.

    METHODS: In this study, RAW264.7 macrophages were incubated with ALE alone for 26 hours or ALE for 2 hours, followed by bacterial lipopolysaccharide for 24 hours. The nitrite and cytokine production (tumour necrosis factor-alpha (TNFα), interleukin (IL)-1β, IL-6, and IL-10), inducible nitric oxide synthase (iNOS), and cyclooxygenase-2 (COX2) expression in the macrophages were assayed.

    RESULTS: The study showed that ALE alone was immunostimulatory on the macrophages by increasing the nitrite, TNFα, and IL-6 production and COX2 expression (p<0.05 vs. untreated unstimulated cells). Pre-treatment of ALE suppressed nitrite level and iNOS expression but enhanced TNFα and IL-6 production and COX2 expression (p<0.05 vs. untreated lipopolysaccharides (LPS)-stimulated cells). ALE also increased IL-10 production regardless of LPS stimulation (p<0.05 vs. untreated cells).

    CONCLUSION: ALE was able to promote the immune response of macrophages by upregulating pro-inflammatory cytokine levels and COX2 expression. It also regulated the extent of the inflammation by reducing iNOS expression and increasing IL-10 levels. Thus, ALE may have a role in enhancing the innate immune system against infection; however, its validation from in vivo studies is still pending.

    Matched MeSH terms: Nitric Oxide/metabolism
  15. Jaafar MN, Ishak MS, Saharin S
    Environ Sci Technol, 2010 Apr 15;44(8):3111-5.
    PMID: 20345095 DOI: 10.1021/es903606y
    This paper presents the development of an emissions-controlling technique for oil burners aimed especially to reduce oxides of nitrogen (NOx). Another emission of interest is carbon monoxide (CO). In this research, a liquid fuel burner is used. In the first part, five different radial air swirler blade angles, 30 degrees , 40 degrees , 45 degrees , 50 degrees , and 60 degrees , respectively, have been investigated using a combustor with 163 mm inside diameter and 280 mm length. Tests were conducted using kerosene as fuel. Fuel was injected at the back plate of the swirler outlet. The swirler blade angles and equivalence ratios were varied. A NOx reduction of more than 28% and CO emissions reduction of more than 40% were achieved for blade angle of 60 degrees compared to the 30 degrees blade angle. The second part of this paper presents the insertion of an orifice plate at the exit plane of the air swirler outlet. Three different orifice plate diameters of 35, 40, and 45 mm were used with a 45 degrees radial air swirler vane angle. The fuel flow rates and orifice plate's sizes were varied. NOx reduction of more than 30% and CO emissions reduction of more than 25% were obtained using the 25 mm diameter orifice plate compared to the test configuration without the orifice plate. The last part of this paper presents tests conducted using the air-staging method. An industrial oil burner system was investigated using the air staging method in order to reduce emission, especially NOx. Emissions reduction of 30% and 16.7% were obtained for NOx and CO emissions, respectively, when using air staging compared to the non-air-staging tests.
    Matched MeSH terms: Nitric Oxide/isolation & purification*
  16. Rashedul HK, Kalam MA, Masjuki HH, Teoh YH, How HG, Monirul IM, et al.
    Environ Sci Pollut Res Int, 2017 Apr;24(10):9305-9313.
    PMID: 28233198 DOI: 10.1007/s11356-017-8573-9
    The study represents a comprehensive analysis of engine exhaust emission variation from a compression ignition (CI) diesel engine fueled with diesel-biodiesel blends. Biodiesel used in this investigation was produced through transesterification procedure from Moringa oleifera oil. A single cylinder, four-stroke, water-cooled, naturally aspirated diesel engine was used for this purpose. The pollutants from the exhaust of the engine that are monitored in this study are nitrogen oxide (NO), carbon monoxide (CO), hydrocarbon (HC), and smoke opacity. Engine combustion and performance parameters are also measured together with exhaust emission data. Some researchers have reported that the reason for higher NO emission of biodiesel is higher prompt NO formation. The use of antioxidant-treated biodiesel in a diesel engine is a promising approach because antioxidants reduce the formation of free radicals, which are responsible for the formation of prompt NO during combustion. Two different antioxidant additives namely 2,6-di-tert-butyl-4-methylphenol (BHT) and 2,2'-methylenebis(4-methyl-6-tert-butylphenol) (MBEBP) were individually dissolved at a concentration of 1% by volume in MB30 (30% moringa biodiesel with 70% diesel) fuel blend to investigate and compare NO as well as other emissions. The result shows that both antioxidants reduced NO emission significantly; however, HC, CO, and smoke were found slightly higher compared to pure biodiesel blends, but not more than the baseline fuel diesel. The result also shows that both antioxidants were quite effective in reducing peak heat release rate (HRR) and brake-specific fuel consumption (BSFC) as well as improving brake thermal efficiency (BTE) and oxidation stability. Based on this study, antioxidant-treated M. oleifera biodiesel blend (MB30) can be used as a very promising alternative source of fuel in diesel engine without any modifications.
    Matched MeSH terms: Nitric Oxide
  17. Imdadul HK, Zulkifli NW, Masjuki HH, Kalam MA, Kamruzzaman M, Rashed MM, et al.
    Environ Sci Pollut Res Int, 2017 Jan;24(3):2350-2363.
    PMID: 27815850 DOI: 10.1007/s11356-016-7847-y
    Exploring new renewable energy sources as a substitute of petroleum reserves is necessary due to fulfilling the oncoming energy needs for industry and transportation systems. In this quest, a lot of research is going on to expose different kinds of new biodiesel sources. The non-edible oil from candlenut possesses the potential as a feedstock for biodiesel production. The present study aims to produce biodiesel from crude candlenut oil by using two-step transesterification process, and 10%, 20%, and 30% of biodiesel were mixed with diesel fuel as test blends for engine testing. Fourier transform infrared (FTIR) and gas chromatography (GC) were performed and analyzed to characterize the biodiesel. Also, the fuel properties of biodiesel and its blends were measured and compared with the specified standards. The thermal stability of the fuel blends was measured by thermogravimetric analysis (TGA) and differential scan calorimetry (DSC) analysis. Engine characteristics were measured in a Yanmar TF120M single cylinder direct injection (DI) diesel engine. Biodiesel produced from candlenut oil contained 15% free fatty acid (FFA), and two-step esterification and transesterification were used. FTIR and GC remarked the biodiesels' existing functional groups and fatty acid methyl ester (FAME) composition. The thermal analysis of the biodiesel blends certified about the blends' stability regarding thermal degradation, melting and crystallization temperature, oxidative temperature, and storage stability. The brake power (BP), brake specific fuel consumption (BSFC), and brake thermal efficiency (BTE) of the biodiesel blends decreased slightly with an increasing pattern of nitric oxide (NO) emission. However, the hydrocarbon (HC) and carbon monoxides (CO) of biodiesel blends were found decreased.
    Matched MeSH terms: Nitric Oxide/analysis
  18. Tan KC, Lim HS, Mat Jafri MZ
    Environ Sci Pollut Res Int, 2014 Jun;21(12):7567-77.
    PMID: 24599658 DOI: 10.1007/s11356-014-2697-y
    This study aimed to predict monthly columnar ozone (O3) in Peninsular Malaysia by using data on the concentration of environmental pollutants. Data (2003-2008) on five atmospheric pollutant gases (CO2, O3, CH4, NO2, and H2O vapor) retrieved from the satellite Scanning Imaging Absorption Spectrometer for Atmospheric Chartography (SCIAMACHY) were employed to develop a model that predicts columnar ozone through multiple linear regression. In the entire period, the pollutants were highly correlated (R = 0.811 for the southwest monsoon, R = 0.803 for the northeast monsoon) with predicted columnar ozone. The results of the validation of columnar ozone with column ozone from SCIAMACHY showed a high correlation coefficient (R = 0.752-0.802), indicating the model's accuracy and efficiency. Statistical analysis was utilized to determine the effects of each atmospheric pollutant on columnar ozone. A model that can retrieve columnar ozone in Peninsular Malaysia was developed to provide air quality information. These results are encouraging and accurate and can be used in early warning of the population to comply with air quality standards.
    Matched MeSH terms: Nitric Oxide/analysis
  19. Inayat A, Rocha-Meneses L, Ayoub M, Ullah S, Abdullah AZ, Naqvi SR, et al.
    Environ Sci Pollut Res Int, 2023 Jun;30(28):72224-72235.
    PMID: 37170050 DOI: 10.1007/s11356-023-27371-w
    This study investigated the effect of different Co3O4-based catalysts on the catalytic decomposition of nitrous oxide (N2O) and on nitric oxide (NO) conversion. The experiments were carried out using various reaction temperatures, alkaline solutions, pH, mixing conditions, aging times, space velocities, impregnation loads, and compounds. The results showed that Co3O4 catalysts prepared by precipitation methods have the highest catalytic activity and N2O conversion, even at low reaction temperatures, while the commercial nano and powder forms of Co3O4 (CS) have the lowest performance. The catalysts become inactive at temperatures below 400 °C, and their activity is strongly influenced by the mixing temperature. Samples without stirring during the aging process have higher catalytic activity than those with stirring, even at low reaction temperatures (200-300 °C). The catalytic activity of Co3O4 PM1 decreases with low W/F values and low reaction temperatures. Additionally, the catalyst's performance tends to increase with the reduction process. The study suggests that cobalt-oxide-based catalysts are effective in N2O catalytic decomposition and NO conversion. The findings may be useful in the design and optimization of catalytic systems for N2O and NO control. The results obtained provide important insights into the development of highly efficient, low-cost, and sustainable catalysts for environmental protection.
    Matched MeSH terms: Nitric Oxide*
  20. Hossain KA, Mohd-Jaafar MN, Appalanidu KB, Mustafa A, Ani FN
    Environ Technol, 2005 Mar;26(3):251-9.
    PMID: 15881021
    Selective Non-Catalytic Reduction (SNCR) of nitric oxide has been studied experimentally by injecting aqueous urea solution with and without additive in a pilot-scale diesel fired tunnel furnace at 3.4% excess oxygen level and with low ppm of baseline NO(x) ranging from 65 to 75 ppm within the investigated temperature range. The tests have been carried out using commercial grade urea as NO(x) reducing agent and commercial grade sodium carbonate as additive. The furnace simulated the small-scale combustion systems, where the operating temperatures are usually in the range of about 973 to 1323 K and NO(x) emission level remains below 100 ppm. With 5% plain urea solution, at Normalized Stoichiometric Ratio (NSR) of 4 as much as 54% reduction was achieved at 1128 K, whilst in the additive case the NO(x) reduction was improved to as much as 69% at 1093 K. Apart from this improvement, in the additive case, the effective temperature window as well as peak temperature of NO(x) reduction shifted towards lower temperatures. The result is quite significant, especially for this investigated level of baseline NO(x). The ammonia slip measurements showed that in both cases the slip was below 16 ppm at NSR of 4 and optimum temperature of NO(x) reduction. Finally, the investigations demonstrated that urea based SNCR is quite applicable to small-scale combustion applications and commercial grade sodium carbonate is a potential additive.
    Matched MeSH terms: Nitric Oxide/chemistry*
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