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1.
The effect of arginine on oral biofilm communities.
Nascimento, MM, Browngardt, C, Xiaohui, X, Klepac-Ceraj, V, Paster, BJ, Burne, RA
Molecular oral microbiology. 2014;(1):45-54
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Abstract
Alkali production by oral bacteria via the arginine deiminase system (ADS) increases the pH of oral biofilms and reduces the risk for development of carious lesions. This study tested the hypothesis that increased availability of arginine in the oral environment through an exogenous source enhances the ADS activity levels in saliva and dental plaque. Saliva and supra-gingival plaque samples were collected from 19 caries-free (CF) individuals (DMFT = 0) and 19 caries-active (CA) individuals (DMFT ≥ 2) before and after treatment, which comprised the use of a fluoride-free toothpaste containing 1.5% arginine, or a regular fluoride-containing toothpaste twice daily for 4 weeks. ADS activity was measured by quantification of ammonia produced from arginine by oral samples at baseline, after washout period, 4 weeks of treatment, and 2 weeks post-treatment. Higher ADS activity levels were observed in plaque samples from CF compared to those of CA individuals (P = 0.048) at baseline. The use of the arginine toothpaste significantly increased ADS activity in plaque of CA individuals (P = 0.026). The plaque microbial profiles of CA treated with the arginine toothpaste showed a shift in bacterial composition to a healthier community, more similar to that of CF individuals. Thus, an anti-caries effect may be expected from arginine-containing formulations due in large part to the enhancement of ADS activity levels and potential favorable modification to the composition of the oral microbiome.
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2.
Insulin-mediated activation of the L-arginine nitric oxide pathway in man, and its impairment in diabetes.
Rajapakse, NW, Chong, AL, Zhang, WZ, Kaye, DM
PloS one. 2013;(5):e61840
Abstract
AIMS/HYPOTHESIS Impaired L-arginine transport has been reported in cardiovascular diseases, providing a possible mechanism for reduced nitric oxide (NO) production. Given that cardiovascular diseases are also associated with insulin resistance, and insulin is known to induce vasodilation via a NO-dependent pathway, we hypothesised that abnormal insulin modulation of L-arginine transport may contribute to vascular dysfunction in diabetes. METHODS Forearm blood flow (FBF) responses to insulin and sodium nitroprusside (SNP) were measured in control and type 2 diabetic volunteers using venous occlusion plethysmography. Effects of intra-arterial insulin on the forearm veno-arterial flux of arginine and related amino acids were determined by HPLC. The effect of locally delivered insulin on arginine transport was assessed during an intra-arterial infusion of [4,5-(3)H] L-arginine. RESULTS In controls, intrabrachial infusion of 5 mUnits/min insulin lead to a progressive rise in FBF (p<0.001) while this was not evident in diabetics. In support of this observation, we observed a concomitant, significant increase in the flux of N-hydroxy-L-arginine (the NO precursor) in controls (baseline vs. 60 mins insulin: 16.2±12.2 vs. 33.0±13.1 nmol/100 ml tissue/min; p<0.01), whilst no increase was observed in diabetics. Moreover, insulin augmented the clearance of [(3)H]L-arginine from the forearm circulation in controls (baseline vs insulin: 123±22 vs. 150±28 ml/min; p<0.05) but not in diabetics. CONCLUSION These findings suggest that insulin resistance may contribute substantially to the onset and development of cardiovascular disease in type 2 diabetics via abnormal insulin-mediated regulation of L-arginine transport.
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Effects of vitamin C on intracoronary L-arginine dependent coronary vasodilatation in patients with stable angina.
Tousoulis, D, Xenakis, C, Tentolouris, C, Davies, G, Antoniades, C, Crake, T, Stefanadis, C
Heart (British Cardiac Society). 2005;(10):1319-23
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Abstract
OBJECTIVE To assess the effects of intravenous vitamin C administration on the vasomotor responses to intracoronary L-arginine infusion in epicardial coronary arteries. METHODS 28 patients with coronary artery disease and stable angina were enrolled in the study. Eight patients received intracoronary infusions of 150 micromol/min L-arginine before and after intravenous infusion of vitamin C, 10 patients received intracoronary infusions of 150 micromol/min L-arginine before and after intravenous infusion of normal saline, and 10 patients received intracoronary normal saline before and after intravenous infusion of vitamin C. The diameter of proximal and distal coronary artery segments was measured by quantitative angiography. RESULTS Infusion of L-arginine caused significant dilatation of both proximal (4.87 (0.96)%, p < 0.01 v normal saline) and distal (6.33 (1.38)%, p < 0.01 v normal saline) coronary segments. Co-infusion of vitamin C and L-arginine dilated proximal coronary segments by 8.68 (1.40)% (p < 0.01 v normal saline, p < 0.01 v L-arginine) and distal segments by 13.07 (2.15)% (p < 0.01 v normal saline, p < 0.01 v L-arginine). Intravenous infusion of vitamin C caused a borderline increase in proximal and distal coronary segment diameters (1.93 (0.76)% and 2.09 (1.28)%, respectively, not significant). CONCLUSIONS L-arginine dependent coronary segment vasodilatation was augmented by the antioxidant vitamin C in patients with coronary artery disease. Thus, vitamin C may have beneficial effects on nitric oxide bioavailability induced by L-arginine.
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Role of enteral immunonutrition in patients with gastric carcinoma undergoing major surgery.
Chen, DW, Wei Fei, Z, Zhang, YC, Ou, JM, Xu, J
Asian journal of surgery. 2005;(2):121-4
Abstract
OBJECTIVE To evaluate the influence of postoperative immunonutrition on immune and nutritional parameters in patients with gastric carcinoma. METHODS From September 2002 to August 2003, 40 patients with gastric carcinoma who had undergone major surgery were randomly divided into an immunonutrition group and standard nutrition group, each of 20 patients. On postoperative Day 2, patients in the standard nutrition group received a standard enteral formula, while those in the immunonutrition group received an enteral formula enriched with glutamine, arginine and omega-3 fatty acids. Nutritional support was continued for 7 days. Blood samples were obtained to determine plasma albumin, prealbumin and transferrin on Days 0, 5 and 9. On Days 0, 1 and 9, blood samples were collected to detect immunoglobulin (Ig) A, IgG, IgM, CD4 and CD8 cell counts, the ratio of CD4/CD8, interleukin (IL)-2, IL-6 and tumour necrosis factor (TNF)-alpha, respectively. RESULTS There were no significant differences between the two groups in protein and immune parameters preoperatively and no significant differences in management perioperatively. No serious adverse effects were recorded with the two formulas. Postoperative procedures were smooth in both groups. On Day 9, serum levels of prealbumin and transferrin were higher in the immunonutrition group than in the standard nutrition group (p<0.01). After 7 days' nutritional support, patients in the immunonutrition group had higher levels of immunoglobulin, CD4 cell counts, CD4/CD8 ratio and IL-2 than those in the control group, whereas IL-6 and TNF-alpha levels were significantly lower in the immunonutrition group. CONCLUSION Compared with standard enteral nutrition, enteral immunonutrition can improve defence mechanisms and modulate inflammatory action after major elective surgery for gastric carcinoma.
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Arginine as an adjuvant to chemotherapy improves clinical outcome in active tuberculosis.
Schön, T, Elias, D, Moges, F, Melese, E, Tessema, T, Stendahl, O, Britton, S, Sundqvist, T
The European respiratory journal. 2003;(3):483-8
Abstract
Nitric oxide (NO) is involved in the host defence against tuberculosis (TB). Patients with TB exhibit increased catabolism and reduced energy intake. Thus the hypothesis for this study was that restoring a relative deficiency in the amino acid arginine, the substrate for mycobactericidal NO production, would improve the clinical outcome of TB by increasing NO production. In a randomised double-blind study, patients with smear-positive TB (n = 120) were given arginine or placebo for 4 weeks in addition to conventional chemotherapy. Primary outcomes were sputum conversion, weight gain, and clinical symptoms after week 8. Secondary outcomes were sedimentation rate and levels of NO metabolites, arginine, citrulline, and tumour necrosis factor-a. Compared with the human immunodeficiency virus (HIV)-/TB+ placebo group, the HIV-/TB+ patients in the arginine group showed significant improvement, defined as increased weight gain, higher sputum conversion rate and faster reduction of symptoms, such as cough. The arginine level increased after week 2 in the HIV-/TB+ arginine group (100.2 microM (range 90.5-109.9) versus 142.1 microM (range 114.1-170.1)) compared with the HIV-/TB+ placebo group (105.5 microM (range 93.7-117.3) versus 95.7 microM (range 82.4-108.9)). HIV seroprevalence was 52.5%. No clinical improvement or increase in serum arginine was detected in arginine supplemented HIV+/TB+ patients compared with placebo. Arginine is beneficial as an adjuvant treatment in human immunodeficiency virus-negative patients with active tuberculosis, most likely mediated by increased production of nitric oxide.
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IGF-I does not affect the net increase in GH release in response to arginine.
Nass, R, Pezzoli, SS, Chapman, IM, Patrie, J, Hintz, RL, Hartman, ML, Thorner, MO
American journal of physiology. Endocrinology and metabolism. 2002;(4):E702-10
Abstract
Arginine stimulates growth hormone (GH) secretion, possibly by inhibiting hypothalamic somatostatin (SS) release. Insulin-like growth factor I (IGF-I) inhibits GH secretion via effects at the pituitary and/or hypothalamus. We hypothesized that if the dominant action of IGF-I is to suppress GH release at the level of the pituitary, then the arginine-induced net increase in GH concentration would be unaffected by an IGF-I infusion. Eight healthy young adults (3 women, 5 men) were studied on day 2 of a 47-h fast for 12 h (35th-47th h) on four occasions. Saline (Sal) or 10 microg. kg(-1). h(-1) recombinant human IGF-I was infused intravenously for 5 h from 37 to 42 h of the 47-h fast. Arginine (Arg) (30 g iv) or Sal was infused over 30 min during the IGF-I or Sal infusion from 40 to 40.5 h of the fast. Subjects received the following combinations of treatments in random order: 1) Sal + Sal; 2) Sal + Arg; 3) IGF-I + Sal; 4) IGF-I + Arg. Peak GH concentration on the IGF-I + Arg day was ~45% of that on the Sal + Arg day. The effect of arginine on net GH release was calculated as [(Sal + Arg) - (Sal + Sal)] - [(IGF-I + Arg) - (IGF-I + Sal)]. There was no significant effect of IGF-I on net arginine-induced GH release over control conditions. These findings suggest that the negative feedback effect of IGF-I on GH secretion is primarily mediated at the pituitary level and/or at the hypothalamus through a mechanism different from the stimulatory effect of arginine.
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Atorvastatin but not L-arginine improves endothelial function in type I diabetes mellitus: a double-blind study.
Mullen, MJ, Wright, D, Donald, AE, Thorne, S, Thomson, H, Deanfield, JE
Journal of the American College of Cardiology. 2000;(2):410-6
Abstract
OBJECTIVES We sought to determine the effects of oral L-arginine and the hexamethylglutaryl coenzyme A reductase inhibitor atorvastatin on endothelial function in young patients with type I diabetes mellitus (DM). BACKGROUND Endothelial dysfunction, a key early event in atherosclerosis, occurs in young patients with type I DM, and its reversal may benefit the progression of vascular disease. Cholesterol reduction in L-arginine improve endothelial function in nondiabetic subjects, but their effect in patients with type I DM is unknown. METHODS In a double-blind, 2x2 factorial study, we investigated the effect of L-arginine (7 g twice daily) and atorvastatin (40 mg/day) on conduit artery vascular function in 84 normocholesterolemic young adults (mean+/-SD: age 34 years [range 18 to 46], low density lipoprotein [LDL] cholesterol 2.96+/-0.89 mmol/liter) with type I DM. Brachial artery dilation to flow (flow-mediated dilation [FMD]) and to the direct smooth muscle dilator glyceryl trinitrate (GTN) were assessed noninvasively using high resolution ultrasound at baseline and after six weeks of treatment. RESULTS Atorvastatin resulted in a 48+/-10% decrease in serum LDL cholesterol levels, whereas L-arginine levels increased by 247+/-141% after L-arginine therapy. By analysis of covariance, treatment with atorvastatin resulted in a significant increase in FMD (p = 0.018. L-Arginine therapy had no significant effect on endothelial function, and there was no significant change in dilation to GTN after either intervention. CONCLUSIONS In young patients with type I DM, improvement in endothelial dysfunction can be demonstrated after just six weeks of treatment with atorvastatin. In contrast to studies of hypercholesterolemia, however, L-arginine had no benefit. Treatment with atorvastatin at an early stage may have an impact on the progression of atherosclerosis in these high risk patients.
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Arginine intake and risk of coronary heart disease mortality in elderly men.
Oomen, CM, van Erk, MJ, Feskens, EJ, Kok, FJ, Kromhout, D
Arteriosclerosis, thrombosis, and vascular biology. 2000;(9):2134-9
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Abstract
From experimental studies, the hypothesis is derived that the amino acid arginine, the precursor of NO, could restore the impaired endothelial function and increased platelet activation observed in atherosclerosis. We investigated whether dietary intake of arginine is associated with reduced coronary heart disease risk in elderly persons. The study population consisted of 806 men aged 64 to 84 years at baseline who participated in the Zutphen Elderly Study, a population-based cohort followed up for 10 years. Information about habitual food consumption was collected by use of the cross-check dietary history method. Ninety (11.2%) of the 806 men died from coronary heart disease. Mean+/-SD baseline arginine intake was 4. 35+/-1.07 g/d. Meat was the main source of arginine intake (37.1%), followed by bread (13.1%) and milk and milk products (12.1%). Arginine intake was not associated with coronary heart disease mortality. After adjustment for age, the relative risk (RR) for the medium tertile of arginine intake was 0.72 (95% CI 0.44 to 1.18), and the RR for the highest tertile was 0.71 (95% CI 0.43 to 1.19, P: for trend=0.19) compared with the lowest tertile of arginine intake. After additional adjustment for history of coronary heart disease and diabetes mellitus, energy intake, body mass index, smoking habit, physical activity, and other relevant dietary and biological risk factors, the RR was 1.86 (95% CI 1.06 to 3.27) for the medium intake and 1.56 (95% CI 0.83 to 2.93) for the highest intake (P: for trend=0.17). These results do not support the hypothesis that dietary arginine intake lowers the risk of coronary heart disease mortality.