The pharmacodynamics of L-arginine

Rational design to improve the catalytic efficiency and stability of arginine deiminase

Arginine deiminase (ADI) has garnered significant interest because of its ability to objectively eradicate cancer cells and produce L-citrulline. To meet the production demands, this study focused on enhancing the enzyme activity and thermal stability of ADI. In this study, 24 ADI mutants were obtained through computer aid site-specific mutation in the ADI of Enterobacter faecalis. Notably, the specific enzyme activities of F44W, N163P, E220I, E220L, N318E, A336G, T340I, and N382F increased, reaching 1.33-2.53 times that of the original enzyme. This study confirmed that site-specific mutations are critical for optimizing enzyme function. Additionally, the F44W, N163P, E220I, T340I, and A336G mutants demonstrated good thermal stability. The optimal pH for mutant F44W increased to 8, whereas mutants E220I, I244V, A336G, T340I, and N328F maintained an optimal pH of 7.5. Conversely, the M109L, N163P, E220L, I244L, and N318E mutants shad an optimal pH of 7. This study revealed that mutant enzymes with increased activity were more likely to contain mutation sites situated near the four loops associated with catalytic residues, whereas mutations at the dimer junction sites had a higher tendency to enhance enzyme stability. These findings contribute to the development of ADI industrial applications and its modifications.

Review of the evidence of radioprotective potential of creatine and arginine as dietary supplements

PURPOSE

Creatine (Cr) and l-arginine are naturally occurring guanidino compounds, commonly used as ergogenic dietary supplements. Creatine and l-arginine exhibit also a number of non-energy-related features, such as antioxidant, anti-apoptotic, and anti-inflammatory properties, which contribute to their protective action against oxidative stress (OS). In this regard, there are a number of studies emphasizing the protective effect of Cr against OS, which develops in the process of aging, increased physical loads as part of athletes' workouts, as well as a number of neurological diseases and toxic effects associated with xenobiotics and UV irradiation. Against this backdrop, and since ionizing radiation causes OS in cells, leading to radiotoxicity, there is an increasing interest to understand whether Cr has the full potential to serve as an effective radioprotective agent. The extensive literature search did not provide any data on this issue. In this narrative review, we have summarized some of our own experimental data published over the last years addressing the respective radioprotective effects of Cr. Next, we have additionally reviewed the existing data on the radiomodifying effects of l-arginine presented earlier by other research groups.

CONCLUSIONS

Creatine possesses significant radioprotective potential including: (1) radioprotective effect on the survival rate of rats subjected to acute whole-body X-ray irradiation in a LD70/30 dose of 6.5 Gy, (2) radioprotective effect on the population composition of peripheral blood cells, (3) radioprotective effect on the DNA damage of peripheral blood mononuclear cells, (4) radioprotective effect on the hepatocyte nucleus-nucleolar apparatus, and (5) radioprotective effect on the brain and liver Cr-Cr kinase systems of the respective animals. Taking into account these cytoprotective, gene-protective, hepatoprotective and energy-stimulating features of Cr, as well as its significant radioprotective effect on the survival rate of rats, it can be considered as a potentially promising radioprotector for further preclinical and clinical studies. The review of the currently available data on radiomodifying effects of l-arginine has indicated its significant potential as a radioprotector, radiomitigator, and radiosensitizer. However, to prove the effectiveness of arginine (Arg) as a radioprotective agent, it appears necessary to expand and deepen the relevant preclinical studies, and, most importantly, increase the number of proof-of-concept clinical trials, which are evidently lacking as of now.

Assessment of the treatment effectiveness of men with mild and medium degree of erectile dysfunction

OBJECTIVE

. Aim: To assess the effectiveness of monotherapy and complex treatment of patients with erectile dysfunction depending on its severity.

PATIENTS AND METHODS

Materials and Methods: Men with moderate and mild erectile dysfunction took part in the study, who, in turn, were divided into groups, depending on the treatment, with the evaluation of the results of the International Index of Erectile Function (MIEF-15), the state of cavernous hemodynamics and the function of the vascular endothelium before and after treatment.

RESULTS

Results: In patients with an average degree of severity, who received complex treatment including a course of low-energy shock wave therapy, against the background of taking sildenafil and L-arginine, the best results were obtained in the quality of erection and increased cavernous blood flow, which positively affected satisfaction with sexual intercourse and overall satisfaction. It has also been proven that the function of the endothelium was improved in patients receiving L-arginine, due to which there was a probable decrease in endothelin-1. A probable improvement of erectile function was obtained in the group of patients with a mild degree who received L-arginine, and there was no statistical difference from the indicators in the group who received sildenafil, which was confirmed by the data of dopplerography.

CONCLUSION

Conclusions: Patients with an average degree of erectile dysfunction require comprehensive treatment. The use of L-arginine can be an alternative to phosphodiesterase type 5 inhibitors in the treatment of mild erectile dysfunction.

Metabolic improvements of novel microbial fermentation on black tea by Eurotium cristatum

Due to its traditional fermentation, there are obvious limits on the quality improvements in black tea. However, microbial fermentation can provide an abundance of metabolites and improve the flavor of tea. The "golden flower" fungi are widely used in the microbial fermentation of tea and has unique uses in healthcare. To further explore the improvements in black tea quality achieved via microbial fermentation, we used widely targeted metabolomics and metagenomics analyses to investigate the changes in and effects of metabolites and other microorganisms during the interaction between the "golden flower" fungi and black tea. Five key flavor metabolites were detected, the levels of catechin, epigallocatechin gallate, (-)-epicatechin gallate were decreased by different degrees after the inoculation of the "golden flower" fungus, whereas the levels of caffeine and (+)-gallocatechin increased. Botryosphaeriaceae, Botryosphaeriales, Dothideomycetes, Aspergillaceae, Trichocomaceae, and Lecanoromycetes play a positive role in the black tea fermentation process after inoculation with the "golden flower" fungi. D-Ribose can prevent hypoxia-induced apoptosis in cardiac cells, and it shows a strong correlation with Botryosphaeriaceae and Botryosphaeriales. The interaction between microorganisms and metabolites is manifested in tryptophan metabolism, starch and sucrose metabolism, and amino sugar and nucleotide sugar metabolism. In conclusion, the changes in metabolites observed during the fermentation of black tea by "golden flower" fungi are beneficial to human health. This conclusion extends the knowledge of the interaction between the "golden flower" fungi and black tea, and it provides important information for improving the quality of black tea.

Advances in Fabrication Technologies for the Development of Next-Generation Cardiovascular Stents

Coronary artery disease is the most prevalent cardiovascular disease, claiming millions of lives annually around the world. The current treatment includes surgically inserting a tubular construct, called a stent, inside arteries to restore blood flow. However, due to lack of patient-specific design, the commercial products cannot be used with different vessel anatomies. In this review, we have summarized the drawbacks in existing commercial metal stents which face problems of restenosis and inflammatory responses, owing to the development of neointimal hyperplasia. Further, we have highlighted the fabrication of stents using biodegradable polymers, which can circumvent most of the existing limitations. In this regard, we elaborated on the utilization of new fabrication methodologies based on additive manufacturing such as three-dimensional printing to design patient-specific stents. Finally, we have discussed the functionalization of these stent surfaces with suitable bioactive molecules which can prove to enhance their properties in preventing thrombosis and better healing of injured blood vessel lining.

Fibroblasts mediate endothelium response to angiogenic cues in a newly developed 3D stroma engineered model

Three-dimensional stroma engineered models would enable fundamental and applicative studies of human tissues interaction and remodeling in both physiological and pathological conditions. In this work, we propose a 3D vascularized stroma model to be used as in vitro platform for drug testing. A pullulan/dextran-based porous scaffold containing pre-patterned microchannels of 100 μm diameter is used for co-culturing of fibroblasts within the matrix pores and endothelial cells to form the lumen. Optical clearing of the constructs by hyperhydration allows for in-depth imaging of the model up to 1 mm by lightsheet and confocal microscopy. Our 3D vascularized stroma model allows for higher viability, metabolism and cytokines expression compared to a monocultured vascular model. Stroma-endothelium cross-talk is then investigated by exposing the system to pro and anti-angiogenic molecules. The results highlight the protective role played by fibroblasts on the vasculature, as demonstrated by decreased cytotoxicity, restoration of nitric oxide levels upon challenge, and sustained expression of endothelial markers CD31, vWF and VEGF. Our tissue model provides a 3D engineered platform for in vitro studies of stroma remodeling in angiogenesis-driven events, known to be a leading mechanism in diseased conditions, such as metastatic cancers, retinopathies and ischemia, and to investigate related potential therapies.

The Emerging Role of Prediabetes and Its Management: Focus on L-Arginine and a Survey in Clinical Practice

The worldwide impressive growth of metabolic disorders observed in the last decades, especially type 2 diabetes mellitus and obesity, has generated great interest in the potential benefits of early identification and management of patients at risk. In this view, prediabetes represents a high-risk condition for the development of type 2 diabetes mellitus and cardiovascular diseases, and an ideal target to intercept patients before they develop type 2 diabetes gaining a prominent role even in international guidelines. For prediabetic individuals, lifestyle modification is the cornerstone of diabetes prevention, with evidence of about 50% relative risk reduction. Accumulating data also show potential benefits from pharmacotherapy. In this context, the only available data pertain to metformin as a pharmaceutical drug and vitamin D and L-arginine as nutraceuticals. L-arginine appears to be a very interesting tool in the clinical management of patients with pre-diabetes. In this review we summarize the current knowledge on the role of L-arginine in prediabetes as a potentially useful preventive strategy against the progression to type 2 diabetes, with a particular focus on the underlying molecular mechanisms and the past and ongoing trials. In this article we also report the interesting data about the perception of the prediabetic condition and its therapeutic management in the clinical practice in Italy. An early identification and a prompt management of people with prediabetes appears to be of paramount importance to prevent the progression to diabetes and avoid its cardiovascular consequences.

The effects of a comparatively higher dose of 1000 mg/kg/d of oral L- or D-arginine on the L-arginine metabolic pathways in male Sprague-Dawley rats

Oral L-arginine supplements are popular mainly for their nitric oxide mediated vasodilation, but their physiological impact is not fully known. L-arginine is a substrate of several enzymes including arginase, nitric oxide synthase, arginine decarboxylase, and arginine: glycine amidinotransferase (AGAT). We have published a study on the physiological impact of oral L- and D-arginine at 500 mg/kg/day for 4 wks in male Sprague-Dawley rats. We investigated the effects of oral L-arginine and D-arginine at a higher dose of 1000 mg/kg/d for a longer treatment duration of 16 wks in 9-week-old male Sprague-Dawley rats. We measured the expression and activity of L-arginine metabolizing enzymes, and levels of their metabolites in the plasma and various organs. L-arginine did not affect the levels of L-arginine and L-lysine in the plasma and various organs. L-arginine decreased arginase protein expression in the upper small intestine, and arginase activity in the plasma. It also decreased AGAT protein expression in the liver, and creatinine levels in the urine. L-arginine altered arginine decarboxylase protein expression in the upper small intestine and liver, with increased total polyamines plasma levels. Endothelial nitric oxide synthase protein was increased with D-arginine, the presumed metabolically inert isomer, but not L-arginine. In conclusion, oral L-arginine and D-arginine at a higher dose and longer treatment duration significantly altered various enzymes and metabolites in the arginine metabolic pathways, which differed from alterations produced by a lower dose shorter duration treatment published earlier. Further studies with differing doses and duration would allow for a better understanding of oral L-arginine uses, and evidence based safe and effective dose range and duration.

Regulated Arginine Metabolism in Immunopathogenesis of a Wide Range of Diseases: Is There a Way to Pass between Scylla and Charybdis?

More than a century has passed since arginine was discovered, but the metabolism of the amino acid never ceases to amaze researchers. Being a conditionally essential amino acid, arginine performs many important homeostatic functions in the body; it is involved in the regulation of the cardiovascular system and regeneration processes. In recent years, more and more facts have been accumulating that demonstrate a close relationship between arginine metabolic pathways and immune responses. This opens new opportunities for the development of original ways to treat diseases associated with suppressed or increased activity of the immune system. In this review, we analyze the literature describing the role of arginine metabolism in the immunopathogenesis of a wide range of diseases, and discuss arginine-dependent processes as a possible target for therapeutic approaches.

The Role of L-Arginine-NO System in Female Reproduction: A Narrative Review

Accumulating evidence are available on the involvement of l-arginine-nitric oxide (NO) system in complex biological processes and numerous clinical conditions. Particular attention was made to reveal the association of l-arginine and methylarginines to outcome measures of women undergoing in vitro fertilization (IVF). This review attempts to summarize the expression and function of the essential elements of this system with particular reference to the different stages of female reproduction. A literature search was performed on the PubMed and Google Scholar systems. Publications were selected for evaluation according to the results presented in the Abstract. The regulatory role of NO during the period of folliculogenesis, oocyte maturation, fertilization, embryogenesis, implantation, placentation, pregnancy, and delivery was surveyed. The major aspects of cellular l-arginine uptake via cationic amino acid transporters (CATs), arginine catabolism by nitric oxide synthases (NOSs) to NO and l-citrulline and by arginase to ornithine, and polyamines are presented. The importance of NOS inhibition by methylated arginines and the redox-sensitive elements of the process of NO generation are also shown. The l-arginine-NO system plays a crucial role in all stages of female reproduction. Insufficiently low or excessively high rates of NO generation may have adverse influences on IVF outcome.

Human arginase 1, a Jack of all trades?

Arginine, a conditionally essential amino acid, plays a crucial role in several metabolic and signalling pathways. Arginine metabolism in the body can be significantly increased under stress or during certain pathological conditions. Depletion of circulating arginine by administering arginine-hydrolysing enzyme has been shown to mitigate varied pathophysiological conditions ranging from cancer, inflammatory conditions, and microbial infection. This review provides an overview of such intriguing expanse of potential applications of recombinant human arginase 1 for different pathological conditions and its status of development.

One-Week L-Arginine Supplementation Had No Effect on 200m Freestyle Swimming Time Trial in Moderately-Trained Male Swimmers

Research on the effect of L-arginine supplementation on exercise performance is still inconsistent and its influence on single-bout swimming performance has not been investigated. Therefore, the aim of this study was to assess if one-week L-arginine supplementation would enhance 200-m freestyle swimming performance in trained/developmental (regularly training ∼3 times per week with a purpose to compete) male swimmers. In a randomized, cross-over, double-blind design, 8 trained/developmental male swimmers (age 25 ± 5 years; mean ± SD) completed 200-m freestyle swimming time-trial on 3 separate occasions: a control trial; and after 2 separate 7-d supplementation periods, with a daily dose of either 8 g/d of L-arginine or placebo trials. Blood lactate concentration was measured immediately post time-trial swimming. Completion time of the 200-m freestyle swimming time-trial did not differ significantly (F = 4.55; P = 0.060; ŋp2 = 0.394) between control (149.40 ± 9.88 s), L-arginine (146.02 ± 10.34 s) and placebo trials (147.58 ± 10.86 s). There was no statistically significant difference in post time-trial swimming blood lactate concentration between trials (control: 11.2 ± 2.7; L-arginine: 13.1 ± 1.8; Placebo: 12.2 ± 2.7, F = 3.52; P = 0.058; ŋp2 = 0.335). One-week of supplementation with 8 g/d of L-arginine, had no ergogenic effect on middle-distance (200-m), freestyle swimming performance in trained/developmental male swimmers.

A Single Dosage of l-Arginine Oral Supplementation Induced Post-Aerobic Exercise Hypotension in Hypertensive Patients

Lowering of peripheral vascular resistance is one of the primary processes involved in blood pressure decrease. Nitric oxide plays a significant role in this process and the availability of l-arginine is a crucial element in nitric oxide biosynthesis. Oral l-arginine supplementation may therefore be a potentiating element in post-exercise hypotension, mediated by its vasodilator action. Thus, the purpose of this study was to investigate if a single dose of l-arginine oral supplementation might impact the post-aerobic exercise blood pressure responses in treated hypertensive individuals. A double-blind, randomized, placebo-controlled crossover trial was conducted. The sample included male (4) and female (6) subjects [62 ± 10 years]. The participants were randomized to ingest one sachet containing 8 grams of l-arginine or placebo (corn starch) dissolved in water (100 ml). The substances were self-administered 120 min before the experimental or control session. The exercise was conducted on a treadmill and consisted of: a 5 min warm-up (50-65% HRreserve); 40 min of running/walking at 60-70% HRreserve; and a 5 min progressive cooldown. After the exercise sessions, blood pressure was measured every 10 min for 60 min. The l-arginine supplementation arm led to significant post-exercise systolic hypotension (mean post-exercise) in relation to rest period (117 ± 12 vs 125 ± 15 mmHg - p = 0.004 [l-arginine] and 121 ± 11 vs 125 ± 15 - p = 0.341 [placebo]). In addition, a systolic net effect of -6.9 ± 3.6 mmHg [p = 0.046] was identified for the mean post-exercise values. Therefore, this study showed that a single dosage of l-arginine oral supplementation induced post-aerobic exercise hypotension in hypertensive patients.

Nitric-Oxide-Inducing Factors on Vitamin D Changes in Older People Susceptible to Suffer from Sarcopenia

Calcium and magnesium, together with vitamin D and the hormones testosterone and cortisol, are key elements in muscle function, to maintain physical fitness. This study aims to analyze if supplementation with NO precursors (L-arginine, L-citrulline and beetroot extract) modulates the circulating levels of calcium, magnesium, vitamin D and steroid hormones in elders. Sixty-one volunteers (65.1 years old, 164.6 cm of height and 71.2 kg of weight) susceptible to develop sarcopenia participated in a physical activity program for 6 weeks. Participants were divided into four groups: one placebo and three taking one of the indicated supplements. Physical capacity was assessed through the following tests: (a) distance covered in 6 min by walking (endurance indicator); (b) hand grip (upper-body strength indicator); (c) time to cover 4 m by walking (speed indicator); and (d) time to perform five full squats (lower-body strength indicator). We concluded that there is a disparity in the association of steroid hormones, vitamin D levels and physical fitness. However, a significant inverse correlation between speed and endurance indicators was observed. Higher circulating vitamin D levels were observed in the L-arginine- and beetroot-supplemented groups. In conclusion, vasodilators increase vitamin D circulating levels that, in the long term, could maintain mineral homeostasis, improving muscular function.

The Potential of L-Arginine in Prevention and Treatment of Disturbed Carbohydrate and Lipid Metabolism—A Review

L-arginine, an endogenous amino acid, is a safe substance that can be found in food. The compound is involved in synthesis of various products responsible for regulatory functions in the body. Particularly noteworthy is, among others, nitric oxide, a signaling molecule regulating carbohydrate and lipid metabolism. The increasing experimental and clinical data indicate that L-arginine supplementation may be helpful in managing disturbed metabolism in obesity, regulate arterial blood pressure or alleviate type 2 diabetes symptoms, but the mechanisms underlying these effects have not been sufficiently elucidated. This review aims to present the up-to-date information regarding the current uses and health-promoting potential of L-arginine, its effects on nitric oxide, carbohydrate and lipid metabolisms, based on the results of in vivo, in vitro studies, and clinical human trials. Available literature suggests that L-arginine may have beneficial effects on human health. However, some studies found that higher dietary L-arginine is associated with worsening of an existing disease or may be potential risk factor for development of some diseases. The mechanisms of regulatory effects of L-arginine on carbohydrate and lipid metabolism have not been fully understood and are currently under investigation.

Intravenous Arginine Administration Attenuates the Inflammatory Response and Improves Metabolic Profiles in Diet-Induced Obese Mice after Sleeve Gastrectomy

Sleeve gastrectomy (SG) is a bariatric surgery that can effectively reduce weight and improve obesity-associated comorbidities. However, surgical stress intensifies inflammation and imbalanced metabolic profiles. Arginine (Arg) is a nutrient with immunomodulatory and anti-inflammatory properties. This study evaluated the short-term effects of Arg administration on adipocyte inflammation and metabolic alterations in obese mice after SG. Mice were assigned to normal and high-fat diet (HFD) groups. After 16 weeks, the HFD group were divided to sham (SH), SG with saline (SS), or Arg (SA) groups. SS and SA groups were postoperatively injected with saline or Arg via the tail vein and sacrificed at day 1 or 3 after the SG, respectively. Results showed that obesity caused elevated plasma glucose and leptin levels. The SG operation enhanced the expression of inflammatory cytokines and macrophage infiltration in adipose tissues, whereas hepatocyte gene expressions associated with lipid β-oxidation were downregulated. Arg treatment reversed the expressions of β-oxidation-associated genes and reduced lipid peroxide production in the liver. Additionally, adipose tissue expressions of inflammatory chemokines were reduced, while the M2 macrophage marker increased after surgery. The findings suggest that postoperative Arg administration elicited more balanced hepatic lipid metabolism, polarized macrophages toward the anti-inflammatory type, and attenuated adipocyte inflammation shortly after SG.

Role of melatonin mediated G-CSF induction in hematopoietic system of gamma-irradiated mice

AIMS

Hematopoietic acute radiation syndrome (H-ARS) can cause lethality, and therefore, the necessity of a safe radioprotector. The present study was focused on investigating the role of melatonin in granulocytes colony-stimulating factor (G-CSF) and related mechanisms underlying the reduction of DNA damage in hematopoietic system of irradiated mice.

MAIN METHODS

C57BL/6 male mice were exposed to 2, 5, and 7.5Gy of whole-body irradiation (WBI), 30 min after intra-peritoneal administration of melatonin with different doses. Mice were sacrificed at different time intervals after WBI, and bone marrow, splenocytes, and peripheral blood lymphocytes were isolated for studying various parameters including micronuclei (MN), cell cycle, comet, γ-H2AX, gene expression, amino acid profiling, and hematology.

KEY FINDINGS

Melatonin100mg/kg ameliorated radiation (7.5Gy and 5Gy) induced MN frequency and cell death in bone marrow without mortality. At 24 h of post-WBI (2Gy), the frequency of micronucleated polychromatic erythrocytes (mnPCE) with different melatonin doses revealed 20 mg/kg as optimal i.p. dose for protecting the hematopoietic system against radiation injury. In comet assay, a significant reduction in radiation-induced % DNA tail (p ≤ 0.05) was observed at this dose. Melatonin reduced γ-H2AX foci/cell and eventually reached to the control level. Melatonin also decreased blood arginine levels in mice after 24 h of WBI. The gene expression of G-CSF, Bcl-2-associated X protein (BAX), and Bcl2 indicated the role of melatonin in G-CSF regulation and downstream pro-survival pathways along with anti-apoptotic activity.

SIGNIFICANCE

The results revealed that melatonin recovers the hematopoietic system of irradiated mice by inducing G-CSF mediated radioprotection.

Short-Term Effects of Supplemental L-Arginine, Diosmin, Troxerutin, and Hesperidin in Diabetic Patients: A Pilot Study

Background and Aims

Inflammatory, oxidative stress, and endothelial dysfunction play a key role in the pathogenesis of long-term cardiovascular complications in patients with diabetes. The present observational prospective study is aimed at evaluating the effects of micronutrients and phytochemicals contained in the dietary supplement Flebotrofine® (AMNOL Chimica Biologica) on biochemical markers of inflammation, endothelial dysfunction, and glycemic control in patients with diabetes.

Methods

105 type 1 or type 2 diabetes patients regularly took a daily dose of the dietary supplement Flebotrofine® for three consecutive months, and haematological and biochemical parameters were checked at baseline, after three months of treatment, and one month after its suspension. Statistical comparison of the laboratory parameters was performed using the two-tailed ANOVA test for repeated samples with a statistical significance level set at p < 0.05.

Results

The daily use of Flebotrofine® did not change the glycemic metabolic compensation of enrolled patients. After three months of regular Flebotrofine® intake, the plasma levels of the antioxidant β-carotene and of arginine were significantly higher compared with the baseline values, with a decrease in the ADMA/arginine ratio. In contrast, apolipoprotein B, ApoB/ApoA1 ratio, and platelet and leukocyte counts significantly dropped.

Conclusion

The daily use of Flebotrofine® might be a valid supplement of arginine, the precursor of NO, and essential in the prevention of endothelial dysfunction. The regular intake of arginine and phytochemicals also improved the antioxidant and antithrombotic profile of enrolled patients. Therefore, Flebotrofine® could be a useful dietary supplement to prevent long-term complications in patients with diabetes.

Immunity boosting nutraceuticals: Current trends and challenges

The immune function of the human body is highly influenced by the dietary intake of certain nutrients and bioactive compounds present in foods. The preventive effects of these bioactive ingredients against various diseases have been well investigated. Functional foods are consumed across various diverse cultures, in some form or the other, which provide benefits greater than the basic nutritional needs. Novel functional foods are being developed using novel bioactive ingredients such as probiotics, polyunsaturated fatty acids, and various phytoconstituents, which have a range of immunomodulatory properties. Apart from immunomodulation, these ingredients also affect immunity by their antioxidant, antibacterial, and antiviral properties. The global pandemic of Severe Acute Respiratory Syndrome Coronavirus-2 has forced the scientific community to race against time to find a proper and effective drug or a vaccine. In this review, various non-pharmacological interventions using nutraceuticals and functional foods have been discussed. PRACTICAL APPLICATIONS: Despite a plethora of research being undertaken to understand the immunity boosting properties of the various bioactive present in food, the findings are not translating to nutraceutical products in the market. Immunity has proved to be one of the most important factors for the health and well-being of an individual, especially when the world has been under the grip of the novel coronavirus Severe Acute Respiratory Syndrome Coronavirus-2. The anti-inflammatory properties of various nutraceuticals can come out as potential inhibitors of the various inflammatory processes such as cytokine storms, usually being observed in COVID 19. This review gives an insight into how various nutraceuticals can help in the prevention of various diseases through different mechanisms. The lack of awareness and proper clinical trials pose a challenge to the nutraceutical industry. This review will help and encourage researchers to further design and develop various functional foods, which might help in building immunity.

Habitual intake of dietary L-arginine in relation to risk of type 2 diabetes: a prospective study

BACKGROUND

There are insufficient data in case of the potential association of habitual dietary L-arginine and the risk of type 2 diabetes mellitus (T2DM) incidence. Here we aimed to examine the potential effect of dietary L-arginine on the T2DM incidence.

METHODS

For this cohort study, 2139 T2DM-free adults from the participations of Tehran Lipid and Glucose Study (TLGS) were recruited. Follow up period was approximately 5.8 years. Daily intakes of protein and L-arginine were estimated using a validated food frequency questionnaire with 168 food item. Hazard Ratios (HRs) and 95% confidence intervals (CIs), adjusted for sex, age, smoking, diabetes risk score, physical activity levels, and total energy intakes as well as carbohydrate, fiber, fats and lysine, were calculated for L-arginine as both absolute intake and its ratio from total protein.

RESULTS

Mean (±SD) age of the participants was 38.9 (±12.6) years and 54.6% were women. Mean (±SD) intake of dietary protein and L-arginine was 77.2 (±22.4) and 4.05 (±1.50) g/d, respectively. An increased risk of T2DM (HR = 2.71, 95% CI = 1.20-6.09) was observed among participants with higher intakes of L-arginine (median intake of > 5.4 vs. 2.69 g/d). Total protein intake and the ratio of L-arginine to total protein intakes were not related to incidence of T2DM in both crude and adjusted models.

CONCLUSION

We found that higher dietary L-arginine levels may increase risk of T2DM and it may have an independent role in T2DM development.

Single Nucleotide Polymorphisms in the Arginase 1 and 2 Genes Are Differentially Associated with Circulating l-Arginine Concentration in Unsupplemented and l-Arginine-Supplemented Adults

BACKGROUND

Genetic variation in arginase may underlie variability in whole blood l-arginine concentrations in unsupplemented and l-arginine-supplemented adults.

OBJECTIVES

We aimed to study whether single nucleotide polymorphisms (SNPs) in the arginase 1 (ARG1) and arginase 2 (ARG2) genes are associated with blood l-arginine concentrations in unsupplemented and l-arginine-supplemented individuals.

METHODS

In 374 adults (mean ± SD age: 59.6 ± 14.6 y; 180 males), we analyzed SNPs in the ARG1 (rs2246012 and rs2781667) and ARG2 genes (rs3742879 and rs2759757) and their associations with blood l-arginine concentrations. We analyzed associations of haplotypes for the ARG1 gene and for the ARG1 and ARG2 genes combined with blood l-arginine concentrations in supplement users and unsupplemented participants.

RESULTS

Of study participants, 120 had low (<42 μmol/L), 133 had medium (42-114 μmol/L), and 121 had high blood l-arginine concentrations (>114 μmol/L); 58 individuals were current l-arginine supplement users. We found a significantly higher prevalence of the minor allele of ARG1 rs2246012 in supplement users with higher blood l-arginine concentrations (P = 0.03). Mean ± SEM l-arginine concentration was 263 ± 9.76 μmol/L in supplement users homozygous for the minor allele of ARG1 rs2246012 (P = 0.004); it was 70.4 ± 25.6 μmol/L in unsupplemented participants homozygous for the minor allele of ARG2 rs3759757 (P = 0.03). The ARG1 haplotype was significantly associated with blood l-arginine concentrations in supplement users (P = 0.046), whereas the combined ARG1/ARG2 haplotype was significantly associated with blood l-arginine concentrations in the cohort as a whole (P = 0.012).

CONCLUSIONS

Genetic variability in the ARG1 and ARG2 genes is associated with blood l-arginine concentrations in humans: ARG1 is associated with blood l-arginine concentrations in l-arginine supplement users, whereas ARG2 is associated with blood l-arginine concentrations in unsupplemented participants. Our study is the first to describe a possible functional relation between ARG1 and ARG2 SNPs and blood l-arginine concentrations; genetic variability in ARG1 may explain variation in blood l-arginine concentrations during supplement use and discrepant study results.

Transport of L-Arginine Related Cardiovascular Risk Markers

L-arginine and its derivatives, asymmetric and symmetric dimethylarginine (ADMA and SDMA) and L-homoarginine, have emerged as cardiovascular biomarkers linked to cardiovascular outcomes and various metabolic and functional pathways such as NO-mediated endothelial function. Cellular uptake and efflux of L-arginine and its derivatives are facilitated by transport proteins. In this respect the cationic amino acid transporters CAT1 and CAT2 (SLC7A1 and SLC7A2) and the system y⁺L amino acid transporters (SLC7A6 and SLC7A7) have been most extensively investigated, so far, but the number of transporters shown to mediate the transport of L-arginine and its derivatives is constantly increasing. In the present review we assess the growing body of evidence regarding the function, expression, and clinical relevance of these transporters and their possible relation to cardiovascular diseases.

Associations of Arginine with Gestational Diabetes Mellitus in a Follow-Up Study

In the reported study we applied the targeted metabolomic profiling employing high pressure liquid chromatography coupled with triple quadrupole tandem mass spectrometry (HPLC–MS/MS) to understand the pathophysiology of gestational diabetes mellitus (GDM), early identification of women who are at risk of developing GDM, and the differences in recovery postpartum between these women and normoglycemic women. We profiled the peripheral blood from patients during the second trimester of pregnancy and three months, and one year postpartum. In the GDM group Arg, Gln, His, Met, Phe and Ser were downregulated with statistical significance in comparison to normoglycemic (NGT) women. From the analysis of the association of all amino acid profiles of GDM and NGT women, several statistical models predicting diabetic status were formulated and compared with the literature, with the arginine-based model as the most promising of the screened ones (area under the curve (AUC) = 0.749). Our research results have shed light on the critical role of arginine in the development of GDM and may help in precisely distinguishing between GDM and NGT and earlier detection of GDM but also in predicting women with the increased type 2 diabetes mellitus (T2DM) risk.

Pre-clinical Research on Bladder Toxicity After Radiotherapy for Pelvic Cancers: State-of-the Art and Challenges

Despite the dramatic advancements in pelvic radiotherapy, urinary toxicity remains a significant side-effect. The assessment of clinico-dosimetric predictors of radiation cystitis (RC) based on clinical data has improved substantially over the last decade; however, a thorough understanding of the physiopathogenetic mechanisms underlying the onset of RC, with its variegated acute and late urinary symptoms, is still largely lacking, and data from pre-clinical research is still limited. The aim of this review is to provide an overview of the main open issues and, ideally, to help investigators in orienting future research. First, anatomy and physiology of bladder, as well as the current knowledge of dose and dose-volume effects in humans, are briefly summarized. Subsequently, pre-clinical radiobiology aspects of RC are discussed. The findings suggest that pre-clinical research on RC in animal models is a lively field of research with growing interest in the development of new radioprotective agents. The availability of new high precision micro-irradiators and the rapid advances in small animal imaging might lead to big improvement into this field. In particular, studies focusing on the definition of dose and fractionation are warranted, especially considering the growing interest in hypo-fractionation and ablative therapies for prostate cancer treatment. Moreover, improvement in radiotherapy plans optimization by selectively reducing radiation dose to more radiosensitive substructures close to the bladder would be of paramount importance. Finally, thanks to new pre-clinical imaging platforms, reliable and reproducible methods to assess the severity of RC in animal models are expected to be developed.

Accumulation of 8-hydroxydeoxyguanosine, L-arginine and Glucose Metabolites by Liver Tumor Cells Are the Important Characteristic Features of Metabolic Syndrome and Non-Alcoholic Steatohepatitis-Associated Hepatocarcinogenesis

To uncover mechanisms and explore novel biomarkers of obesity, type 2 diabetes (T2DM) and nonalcoholic steatohepatitis (NASH)-associated hepatocarcinogenesis, cellular and molecular alterations in the liver, and hepatocellular carcinomas (HCCs) were investigated in NASH model 60-week-old Tsumura, Suzuki, Obese Diabetic (TSOD) mice and NASH HCC patients. Markedly elevated lipid deposition, inflammation, fibrosis, and peroxisome proliferation in the liver, preneoplastic lesions, and HCCs of TSOD mice were accompanied by accumulation of polysaccharides in the cellular cytoplasm and nuclei and increase of oxidative DNA damage marker, 8-hydroxydeoxyguanosine (8-OHdG) formation in the liver and altered foci. Metabolomics of TSOD mice HCCs demonstrated significant elevation of the concentration of amino acid L-arginine, phosphocreatine, S-adenosylmethionine/S-adenosylhomocysteine ratio, adenylate, and guanylate energy charges in coordination with tremendous rise of glucose metabolites, mostly fructose 1,6-diphosphate. L-arginine accumulation in HCCs was associated with significant under-expression of arginase 1 (ARG1), suppression of the urea cycle, methionine and putrescine degradation pathways, activation of Ser and Thr kinase Akt AKT, phosphoinositide 3-kinase (PI3K), extracellular signal-regulated kinase 1/2 (ERK1/2) kinases, β-catenin, mammalian target of rapamycin (mTOR), and cell proliferation. Furthermore, clinicopathological analysis in 20 metabolic syndrome/NASH and 80 HCV-positive HCC patients demonstrated significant correlation of negative ARG1 expression with poor tumor differentiation, higher pathological stage, and significant decrease of survival in metabolic syndrome/NASH-associated HCC patients, thus indicating that ARG1 could become a potential marker for NASH HCC. From these results, formation of oxidative stress and 8-OHdG in the DNA and elevation of glucose metabolites and L-arginine due to ARG1 suppression in mice liver cells are the important characteristics of T2DM/NASH-associated hepatocarcinogenesis, which may take part in activating oxidative stress resistance, synthesis of phosphocreatine, cell signaling, methylation, and proliferation.

A Paradoxical Vasodilatory Nutraceutical Intervention for Prevention and Attenuation of Migraine-A Hypothetical Review

Studies suggest that migraine pain has a vascular component. The prevailing dogma is that peripheral vasoconstriction activates baroreceptors in central, large arteries. Dilatation of central vessels stimulates nociceptors and induces cortical spreading depression. Studies investigating nitric oxide (NO) donors support the indicated hypothesis that pain is amplified when acutely administered. In this review, we provide an alternate hypothesis which, if substantiated, may provide therapeutic opportunities for attenuating migraine frequency and severity. We suggest that in migraines, heightened sympathetic tone results in progressive central microvascular constriction. Suboptimal parenchymal blood flow, we suggest, activates nociceptors and triggers headache pain onset. Administration of NO donors could paradoxically promote constriction of the microvasculature as a consequence of larger upstream central artery vasodilatation. Inhibitors of NO production are reported to alleviate migraine pain. We describe how constriction of larger upstream arteries, induced by NO synthesis inhibitors, may result in a compensatory dilatory response of the microvasculature. The restoration of central capillary blood flow may be the primary mechanism for pain relief. Attenuating the propensity for central capillary constriction and promoting a more dilatory phenotype may reduce frequency and severity of migraines. Here, we propose consideration of two dietary nutraceuticals for reducing migraine risk: L-arginine and aged garlic extracts.

Intermittent Hypoxic Exposure with High Dose of Arginine Impact on Circulating Mediators of Tissue Regeneration

Intermittent exposure to hypoxia (IHE) increases production of reactive oxygen and nitrogen species which, as signalling molecules, participate in tissue injury–repair–regeneration cascade. The process is also stimulated by arginine whose bioavailability is a limiting factor for NO synthesis. The effects of IHE in combination with arginine (Arg) intake on myogenesis and angiogenesis mediators were examined in a randomized and placebo-controlled trial. Blood samples were collected from 38 elite athletes on the 1st, 7th and 14th days during the training camp. The oral doses of arginine (2 × 6 g/day) and/or IHE using hypoxicator GO2Altitude (IHE and Arg/IHE) were applied. Serum NO and H₂O₂ concentrations increased significantly and were related to muscle damage (CK activity >900 IU/mL) in IHE and Arg/IHE compared to placebo. The changes in NO and H₂O₂ elevated the levels of circulating growth factors such as HGF, IHG-1, PDGF^BB, BDNF, VEGF and EPO. Modification of the lipid profile, especially reduced non-HDL, was an additional beneficial effect of hypoxic exposure with arginine intake. Intermittent hypoxic exposure combined with high-dose arginine intake was demonstrated to affect circulating mediators of injury–repair–regeneration. Therefore, a combination of IHE and arginine seems to be a potential therapeutic and non-pharmacological method to modulate the myogenesis and angiogenesis in elite athletes.

Myeloid Cell-Derived Arginase in Cancer Immune Response

Amino acid metabolism is a critical regulator of the immune response, and its modulating becomes a promising approach in various forms of immunotherapy. Insufficient concentrations of essential amino acids restrict T-cells activation and proliferation. However, only arginases, that degrade L-arginine, as well as enzymes that hydrolyze L-tryptophan are substantially increased in cancer. Two arginase isoforms, ARG1 and ARG2, have been found to be present in tumors and their increased activity usually correlates with more advanced disease and worse clinical prognosis. Nearly all types of myeloid cells were reported to produce arginases and the increased numbers of various populations of myeloid-derived suppressor cells and macrophages correlate with inferior clinical outcomes of cancer patients. Here, we describe the role of arginases produced by myeloid cells in regulating various populations of immune cells, discuss molecular mechanisms of immunoregulatory processes involving L-arginine metabolism and outline therapeutic approaches to mitigate the negative effects of arginases on antitumor immune response. Development of potent arginase inhibitors, with improved pharmacokinetic properties, may lead to the elaboration of novel therapeutic strategies based on targeting immunoregulatory pathways controlled by L-arginine degradation.

Role of Arginase 2 as a potential pharmacological target for the creation of new drugs to correct cardiovascular diseases

Introduction: The review provides relevant information about arginase 2, the role of this enzyme in the formation of endothelial dysfunction and, as a consequence, the development of cardiovascular diseases.

History of the discovery of arginase and its functions: The discovery of arginase took place long before its active study as a substance that affects the formation of endothelial dysfunction.

Role of arginase 2 in the development of a number of cardiovascular diseases: The role of NO synthase and arginase 2 in the formation of oxidative stress is determined. The pathophysiological mechanisms of the development of a number of cardiovascular diseases, such as coronary heart disease, atherosclerosis, and aortic aneurysm, are described. The modern possibilities of treatment of endothelial dysfunction in the pathology of the cardiovascular system and the possibility of creation of new drugs are considered. An increase in the activity of arginase 2 was proven to occur in the case of the development of coronary heart disease (CHD), hypertension, type II diabetes mellitus, hypercholesterolemia, as well as in the process of aging. According to the WHO, coronary heart disease and apoplectic attack have topped the list of causes of death worldwide over the past 15 years.

Arginase 2 as a potential pharmacological target: The purpose of this literature review is to determine the possibilities of use of arginase 2 as a new target for the pharmacological correction of cardiovascular diseases.

l-arginine Supplementation Increased Only Endothelium-Dependent Relaxation in Sprague-Dawley Rats Fed a High-Salt Diet by Enhancing Abdominal Aorta Endothelial Nitric Oxide Synthase Gene Expression

Background

Abnormal vascular reactivity and reduced expression of endothelial nitric oxide synthase (eNOS) gene are hallmark of salt-induced hypertension in rats. Although l-arginine is an established vasodilator, the mechanism by which it modulates vascular reactivity in salt-induced hypertension is not clearly understood.

Objectives

This study was designed to investigate the mechanism by which oral l-arginine supplementation modulates vascular reactivity and eNOS gene expression in Sprague-Dawley rats fed a high-salt diet.

Methods

Forty-eight weaned male Sprague-Dawley rats of weight range 90 to 110 g were randomly divided into 6 groups of 8 rats per group. Group I was fed normal rat chow ad libitum and served as the Normal Diet group. Group II was fed a diet that contained 8% NaCl. Groups III and IV took normal and high-salt diet, respectively, and then received oral l-arginine supplementation (100 mg/kg/day), while groups V and VI took normal and high-salt diet, respectively, and then were co-administered with both l-arginine and l-nitro-arginine methyl ester (L-NAME; 100 mg/kg/day and 40 mg/kg/day, respectively) orally. At the end of 12-week experimental period, the animals were sacrificed to assess vascular reactivity and gene expression level.

Results

Our results show that high-salt diet significantly reduced (P < .05) endothelium-dependent relaxation response to acetylcholine and qualitatively reduced eNOS gene expression in the abdominal aorta of the rats. However, l-arginine supplementation improved the impaired endothelium-dependent relaxation and nitric oxide level while ameliorating the reduced eNOS gene expressions.

Conclusion

This study suggests that oral supplementation of l-arginine enhances endothelial-dependent relaxation in rats fed a high-salt diet by ameliorating eNOS gene expression in the abdominal aorta of the rats.

The Effects of Probiotic Lactobacillus and Bifidobacterium Strains on Memory and Learning Behavior, Long-Term Potentiation (LTP), and Some Biochemical Parameters in β-Amyloid-Induced Rat's Model of Alzheimer's Disease

This study assessed the effects of probiotic supplementation on spatial learning and memory, long-term potentiation (LTP), paired-pulse facilitation (PPF) ratios, nitric oxide (NO) concentrations, and lipid profiles in a rat model of amyloid beta (Aβ)(1–42)-induced Alzheimer’s disease (AD). Forty rats were randomly divided into 4 groups. The sham (control and prevention) group received intracerebroventricular (ICV) injections of artificial cerebrospinal fluid, the Alzheimer group received ICV injection of Aβ(1–42), and the probiotic+Alzheimer group received 500 mg probiotics daily (15×10⁹ colony-forming unit) by gavage for 4 weeks before and 2 weeks after injection of Aβ(1–42). The Morris water maze test was performed for evaluation of spatial learning and memory. LTP and PPF ratios were measured to evaluate longterm synaptic plasticity and pre-synaptic mechanisms, respectively. The results showed that probiotic supplementation significantly improved learning, but not memory impairment, and increased PPF ratios compared to those in the Alzheimer group. Both Aβ(1–42) injection and probiotic supplementation alone did not significantly effect plasma level of NO. Probiotic supplementation of rats in the probiotic (6 weeks)+Alzheimer group decreased serum levels of total cholesterol, triglyceride, and very low-density lipoprotein-cholesterol significantly compared to the Alzheimer group. The results of this study suggest that probiotic supplementation may positively impact learning capacity and LTP in rats with AD, most likely via the release of neurotransmitters via presynaptic mechanisms or via a protective effect on serum lipid profiles.

Malaria in pregnancy alters l-arginine bioavailability and placental vascular development

Reducing adverse birth outcomes due to malaria in pregnancy (MIP) is a global health priority. However, there are few safe and effective interventions. L-arginine is an essential amino acid in pregnancy and an immediate precursor in the biosynthesis of nitric oxide (NO), but there are limited data on the impact of MIP on NO biogenesis. We hypothesized that hypoarginemia contributes to the pathophysiology of MIP and that L-arginine supplementation would improve birth outcomes. In a prospective study of pregnant Malawian women, we show that MIP was associated with lower concentrations of L- arginine and higher concentrations of endogenous inhibitors of NO biosynthesis, asymmetric and symmetric dimethylarginine, which were associated with adverse birth outcomes. In a model of experimental MIP, L-arginine supplementation in dams improved birth outcomes (decreased stillbirth and increased birth weight) compared with controls. The mechanism of action was via normalized angiogenic pathways and enhanced placental vascular development, as visualized by placental microcomputerized tomography imaging. These data define a role for dysregulation of NO biosynthetic pathways in the pathogenesis of MIP and support the evaluation of interventions to enhance L-arginine bioavailability as strategies to improve birth outcomes.

Perspective: L-arginine and L-citrulline Supplementation in Pregnancy: A Potential Strategy to Improve Birth Outcomes in Low-Resource Settings

The available data support the hypothesis that L-arginine or L-citrulline supplementation would be suitable for implementation in resource-constrained settings and will enhance placental vascular development and improve birth outcomes. In resource-constrained settings, the rates of adverse birth outcomes, including fetal growth restriction, preterm birth, and low birth weight, are disproportionately high. Complications resulting from preterm birth are now the leading cause of mortality in children <5 y of age worldwide. Despite the global health burden of adverse birth outcomes, few effective interventions are currently available and new strategies are urgently needed, especially for low-resource settings. L-arginine is a nutritionally essential amino acid in pregnancy and an immediate precursor of nitric oxide. During pregnancy, placental and embryonic growth increases the demand for L-arginine, which can exceed endogenous synthesis of L-arginine from L-citrulline, necessitating increased dietary intake. In many low-resource settings, dietary intake of L-arginine in pregnancy is inadequate owing to widespread protein malnutrition and depletion of endogenous L-arginine due to maternal infections, in particular malaria. Here we examine the role of the L-arginine-nitric oxide biosynthetic pathway in pregnancy including placental vascular development and fetal growth. We review the evidence for the relations between altered L-arginine bioavailability and pregnancy outcomes, and strategies for arginine supplementation in pregnancy. Existing studies of L-arginine supplementation in pregnancy in high-resource settings have shown improved maternal and fetal hemodynamics, prevention of pre-eclampsia, and improved birth outcomes including higher birth weight and longer gestation. Arginine supplementation studies now need to be extended to pregnant women in low-resource settings, especially those at risk of malaria.

L-ARGININE SUPPLEMENTATION IMPROVES POST-EXERCISE HYPOTENSION IN ELDERLY WOMEN

ABSTRACT Introduction: L-Arginine supplementation increases plasma levels of nitric oxide (NO) metabolites, an important mediator of peripheral dilatation. Therefore, L-Arginine supplementation can improve the duration and magnitude of post-exercise hypotension. Objectives: This study investigated the effects of L-Arginine supplementation on post-exercise hypotension, femoral artery area and heart rate variability in elderly women. Methods: Twenty prehypertensive and hypertensive adult female participants were divided (in a random and balanced manner) into two groups (placebo and L-arginine). The participants ingested eight grams of inert substance (placebo group) or eight grams of L-Arginine (L-arginine group), dissolved in water, 90 min prior to the experimental session. The experimental session consisted of an isokinetic maximal strength test. Blood pressure was measured using an oscillometric device (Omron MX3 Plus, Bannockburn, US) every 10 minutes for 60 minutes after the experimental session. Femoral artery area (ultrasound) and heart rate variability were also analyzed. Data underwent repeated measures (ANOVA) analysis and respective assumptions. Results: L-Arginine supplementation associated with exercise produced a significant decrease in systolic blood pressure [placebo vs L-Arginine] (p <0.05) at the “half-life” time point (90 minutes after supplementation) (141±12 vs 130±11 mmHg) and 40 min. (146±13 vs 127±13 mmHg), 50 min. (145±20 vs 127±15 mmHg) and 60 min. (147±19 vs 129±14mmHg) post-exercise. No significant differences were identified in femoral artery area and heart rate variability. Conclusion: Acute L-Arginine supplementation can increase post-exercise hypotension effects in elderly women. Additionally, acute L-Arginine supplementation is not related to either femoral artery area or heart rate variability responses. Level of evidence I; Randomized clinical trial.

Effect of spironolactone for 1 yr on endothelial function and vascular inflammation biomarkers in renal transplant recipients

Kidney transplantation is associated with increased cardiovascular risk. Endothelial dysfunction and vascular inflammation contribute to negative outcome. In experimental models, mineralocorticoid receptor antagonists improved endothelial function and reduced inflammation. The present study tested the hypothesis that the mineralocorticoid receptor antagonist spironolactone improves endothelial function and reduces vascular inflammation in renal transplant patients. Eighty prevalent renal transplant patients from an ongoing, double-blind randomized placebo-controlled trial were included. Paired plasma samples before and after 1 yr of treatment (n = 39 in the spironolactone-treated group and 41 in the placebo-treated group) were used to determine markers of endothelial dysfunction (nitrite, nitrate, cGMP, arginine, citrulline, ornithine, asymmetric dimethylarginine, symmetric dimethylarginine, N^G-monomethyl-l-arginine, von Willebrand factor, tissue-type plasminogen activator antigen, and plasminogen activator inhibitor 1 antigen) and markers of inflammation (intercellular adhesion molecule, vascular adhesion molecule, high-sensitivity C-reactive protein, and serum amyloid protein A). The median time since the transplantation was 4.6 (0.12-22.3) yr in the spironolactone-treated group and 2.1 (0.17-13.9) yr in the placebo-treated group (P > 0.05). Spironolactone increased plasma aldosterone (P < 0.001) and K⁺ (P < 0.001). Blood pressure did not change significantly. No significant differences were detected between groups in any of the measured markers of endothelial dysfunction or inflammation except in the subgroup analysis of patients with diabetes, where spironolactone decreased nitrite compared with placebo. In this study, mineralocorticoid receptor antagonism did not improve biomarkers of endothelial dysfunction or vascular inflammation in prevalent renal transplant patients. Further studies are needed to evaluate the potential beneficial effect of early or late mineralocorticoid receptor antagonism on vascular outcomes in renal transplant patients.

Proteomics and Metabolomics for AKI Diagnosis

Acute kidney injury (AKI) is a severe and frequent condition in hospitalized patients. Currently, no efficient therapy of AKI is available. Therefore, efforts focus on early prevention and potentially early initiation of renal replacement therapy to improve the outcome in AKI. The detection of AKI in hospitalized patients implies the need for early, accurate, robust, and easily accessible biomarkers of AKI evolution and outcome prediction because only a narrow window exists to implement the earlier-described measures. Even more challenging is the multifactorial origin of AKI and the fact that the changes of molecular expression induced by AKI are difficult to distinguish from those of the diseases associated or causing AKI as shock or sepsis. During the past decade, a considerable number of protein biomarkers for AKI have been described and we expect from recent advances in the field of omics technologies that this number will increase further in the future and be extended to other sorts of biomolecules, such as RNAs, lipids, and metabolites. However, most of these biomarkers are poorly defined by their AKI-associated molecular context. In this review, we describe the state-of-the-art tissue and biofluid proteomic and metabolomic technologies and new bioinformatics approaches for proteomic and metabolomic pathway and molecular interaction analysis. In the second part of the review, we focus on AKI-associated proteomic and metabolomic biomarkers and briefly outline their pathophysiological context in AKI.

Sources of Vascular Nitric Oxide and Reactive Oxygen Species and Their Regulation

Nitric oxide (NO) is a small free radical with critical signaling roles in physiology and pathophysiology. The generation of sufficient NO levels to regulate the resistance of the blood vessels and hence the maintenance of adequate blood flow is critical to the healthy performance of the vasculature. A novel paradigm indicates that classical NO synthesis by dedicated NO synthases is supplemented by nitrite reduction pathways under hypoxia. At the same time, reactive oxygen species (ROS), which include superoxide and hydrogen peroxide, are produced in the vascular system for signaling purposes, as effectors of the immune response, or as byproducts of cellular metabolism. NO and ROS can be generated by distinct enzymes or by the same enzyme through alternate reduction and oxidation processes. The latter oxidoreductase systems include NO synthases, molybdopterin enzymes, and hemoglobins, which can form superoxide by reduction of molecular oxygen or NO by reduction of inorganic nitrite. Enzymatic uncoupling, changes in oxygen tension, and the concentration of coenzymes and reductants can modulate the NO/ROS production from these oxidoreductases and determine the redox balance in health and disease. The dysregulation of the mechanisms involved in the generation of NO and ROS is an important cause of cardiovascular disease and target for therapy. In this review we will present the biology of NO and ROS in the cardiovascular system, with special emphasis on their routes of formation and regulation, as well as the therapeutic challenges and opportunities for the management of NO and ROS in cardiovascular disease.

Influence of exercise on oxidative stress in patients with heart failure

Reactive oxygen species play an important role in the pathophysiology of heart failure (HF). In contrast, regular physical exercise can promote adaptations to reactive oxygen species that are beneficial for patients with HF. We completed a systematic review of randomized controlled trials that evaluate the influence of exercise on oxidative stress in patients with HF. Articles were searched in the PubMed, Cochrane, SciELO, and LILACS databases. The search was conducted according to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines. The quality of the included studies was assessed using the Physiotherapy Evidence Database scale. We selected 12 studies with a total of 353 participants. The included patients had a left ventricle ejection fraction of < 52% and New York Heart Association functional class II or III disease. A significant increase was observed in peak oxygen consumption (between 10 and 46%) in the group that underwent training (TG). There was an improvement in the oxidative capacity of skeletal muscles in the TG, related to the positive activity of mitochondrial cytochrome c oxidase (between 27 and 41%). An increase in the expression of the enzymes glutathione peroxidase (41%), catalase (between 14 and 42%), and superoxide dismutase (74.5%), and a decrease in lipid peroxidation (between 28.8 and 58.5%) were observed in the TG. Physical training positively influenced the cardiorespiratory capacity and enhanced the benefits of oxidant and antioxidant biomarkers in patients with HF. High-intensity training promoted a 15% increase in the plasma total antioxidant capacity, whereas moderate training had no effect.

Independent spectral characteristics of functionalized silver nanoparticles for colorimetric assay of arginine and spermine in biofluids

A colorimetric assay for selective and sensitive detection of arginine and spermine using 6-ATT-AgNPs as a probe.

Serum Levels of Asymmetric and Symmetric Dimethylarginine in Women with Vitamin D Deficiency and History of Pregnancy Loss - A Pilot Study

BACKGROUND

Vitamin D deficiency has been reported to be associated with pregnancy loss. Asymmetric dimethyl-L-arginine (ADMA) and symmetric dimethyl-L-arginine (SDMA) are arginine analogues that have direct and indirect effects on nitric oxide (NO) synthesis and endothelial dysfunction. This study aimed to evaluate ADMA and SDMA levels among women with history of pregnancy loss compared to women without history of pregnancy loss and all participants were suffering from vitamin D deficiency.

METHODS

To investigate the relationship between vitamin D deficiency and ADMA and SDMA, both groups of women were experiencing vitamin D deficiency. All women enrolled in this study had a vitamin D level below 75 nmol/L and were not pregnant. ADMA and SDMA levels were investigated in 28 women without a history of pregnancy loss and 19 women with a history of pregnancy loss.

RESULTS

No statistically significant differences were found in ADMA and SDMA levels among the two groups. The correlation analysis showed that vitamin D deficiency was not significantly inversely correlated with ADMA and SDMA in women without a history of pregnancy loss, but was significantly correlated with SDMA in women with a history of pregnancy loss.

CONCLUSIONS

Vitamin D deficiency, in women with or without a history of failed clinical pregnancies, has no effect on the circulating levels of ADMA and SDMA. Further studies are needed to investigate any possible link between these parameters.

NMR-Based Serum Metabolomics Revealed Distinctive Metabolic Patterns in Reactive Arthritis Compared with Rheumatoid Arthritis

Reactive arthritis (ReA) is a member of seronegative spondyloarthropathy (SSA), which involves an acute/subacute onset of asymmetrical lower limb joint inflammation weeks after a genitourinary/gastrointestinal infection. The diagnosis is clinical because it is difficult to culture the microbes from synovial fluid. Arthritis patients with a similar clinical picture but lapsed history of an immediate preceding infection that do not fulfill the diagnostic criteria of other members of SSA, such as ankylosing spondylitis, psoriatic arthritis, and arthritis associated with inflammatory bowel disease, are labeled as peripheral undifferentiated spondyloarthropathy (uSpA). Both ReA and uSpA patients show a strong association with class I major histocompatibility complex allele, HLA-B27, and a clear association with an infectious trigger; however, the disease mechanism is far from clear. Because the clinical picture is largely dominated by rheumatoid-arthritis (RA)-like features including elevated levels of inflammatory markers (such as ESR, CRP, etc.), these overlapping symptoms often confound the clinical diagnosis and represent a clinical dilemma, making treatment choice more generalized. Therefore, there is a compelling need to identify biomarkers that can support the diagnosis of ReA/uSpA. In the present study, we performed NMR-based serum metabolomics analysis and demonstrated that ReA/uSpA patients are clearly distinguishable from controls and further that these patients can also be distinguished from the RA patients based on the metabolic profiles, with high sensitivity and specificity. The discriminatory metabolites were further subjected to area under receiver operating characteristic curve analysis, which led to the identification of four metabolic entities (i.e., valine, leucine, arginine/lysine, and phenylalanine) that could differentiate ReA/uSpA from RA.

Therapeutic regimen of L-arginine for MELAS: 9-year, prospective, multicenter, clinical research

Objective

To examine the efficacy and safety of the therapeutic regimen using oral and intravenous l-arginine for pediatric and adult patients with mitochondrial myopathy, encephalopathy, lactic acidosis, and stroke-like episodes (MELAS).

Methods

In the presence and absence of an ictus of stroke-like episodes within 6 h prior to efficacy assessment, we correspondingly conducted the systematic administration of oral and intravenous l-arginine to 15 and 10 patients with MELAS in two, 2-year, prospective, multicenter clinical trials at 10 medical institutions in Japan. Subsequently, patients were followed up for 7 years. The primary endpoint in the clinical trial of oral l-arginine was the MELAS scale, while that for intravenous l-arginine was the improvement rates of headache and nausea/vomiting at 2 h after completion of the initial intravenous administration. The relationships between the ictuses of stroke-like episodes and plasma arginine concentrations were examined.

Results

Oral l-arginine extended the interictal phase (p = 0.0625) and decreased the incidence and severity of ictuses. Intravenous l-arginine improved the rates of four major symptoms—headache, nausea/vomiting, impaired consciousness, and visual disturbance. The maximal plasma arginine concentration was 167 μmol/L when an ictus developed. Neither death nor bedriddenness occurred during the 2-year clinical trials, and the latter did not develop during the 7-year follow-up despite the progressively neurodegenerative and eventually life-threatening nature of MELAS. No treatment-related adverse events occurred, and the formulations of l-arginine were well tolerated.

Conclusions

The systematic administration of oral and intravenous l-arginine may be therapeutically beneficial and clinically useful for patients with MELAS.