Research Progress on CARM1 and its Relationship with Colorectal Cancer.

Coactivator-associated arginine methyltransferase 1 (CARM1) is significant as a key member of the PRMT family, crucial for regulating arginine methylation, and its association with colorectal cancer underscores its potential as a therapeutic target. Consequently, CARM1 inhibitors have emerged as potential therapeutic agents in cancer treatment and valuable chemical tools for cancer research. Despite steady progress in CARM1 inhibitor research, challenges persist in discovering effective, isoform-selective, cell-permeable, and in vivo-active CARM1 inhibitors for colorectal cancer. This review summarizes the research progress on CARM1 and its relationship with colorectal cancer, aiming to provide a theoretical basis for the radiotherapy of colorectal cancer.

Reduced symmetric dimethylation stabilizes vimentin and promotes metastasis in MTAP-deficient lung cancer.

The aggressive nature and poor prognosis of lung cancer led us to explore the mechanisms driving disease progression. Utilizing our invasive cell-based model, we identified methylthioadenosine phosphorylase (MTAP) and confirmed its suppressive effects on tumorigenesis and metastasis. Patients with low MTAP expression display worse overall and progression-free survival. Mechanistically, accumulation of methylthioadenosine substrate in MTAP-deficient cells reduce the level of protein arginine methyltransferase 5 (PRMT5)-mediated symmetric dimethylarginine (sDMA) modification on proteins. We identify vimentin as a dimethyl-protein whose dimethylation levels drop in response to MTAP deficiency. The sDMA modification on vimentin reduces its protein abundance but trivially affects its filamentous structure. In MTAP-deficient cells, lower sDMA modification prevents ubiquitination-mediated vimentin degradation, thereby stabilizing vimentin and contributing to cell invasion. MTAP and PRMT5 negatively correlate with vimentin in lung cancer samples. Taken together, we propose a mechanism for metastasis involving vimentin post-translational regulation.

Renal biomarkers, clinical parameters, and renal Doppler velocimetry in bitches with cystic endometrial hyperplasia-pyometra complex.

Cystic endometrial hyperplasia (CEH)-pyometra complex is the most common uterine infection in adult and elderly bitches and can cause renal dysfunction. The aim of this study was to measure and compare urinary creatinine, urea, symmetric dimethylarginine (SDMA), urinary protein-creatinine ratio (UPC), measurement of systolic blood pressure (SBP), and Doppler velocimetry of renal arteries in patients with CEH-pyometra complex before and after an average of 6 months of treatment, evaluating the possibility of the changes persisting. The evaluation was conducted at two moments: M1 (at the diagnosis of CEH-pyometra, n = 36) and M2 (after an average of six months of treatment, n = 16). For the control group, eight bitches with no changes in blood tests or history of conditions underwent Doppler ultrasound evaluation of the renal arteries. At both M1 and M2, we measured creatinine, urea, and serum SDMA, UPC, SBP, and Doppler ultrasound of the renal arteries. Patients were evaluated according to the following groups: azotemic (AZO) and non-azotemic (NAZO), and open and closed cervix pyometra. The parameters were compared between animals present in both moments presented as M1R (bitches that were in M1 and M2) and M2. Statistical significance was considered when p < .05. The medians found for creatinine in M1 were as follows: 1.15 mg/dL, being 1.8 mg/dL for AZO (12/36) and 0.95 mg/dL for NAZO (24/36); and in M2: 0.85 mg/dL (16/16), being 1.15 mg/dL for AZO (4/16) and 0.8 mg/dL for NAZO (12/36). For urea, in M1 it was 36 mg/dL (32/36), with AZO being 103 mg/dL (11/32) and 33 mg/dL in NAZO (21/32); and in M2 32 mg/dL (16/ 16), being 29 mg/dL for AZO (4/36), and 31 mg/dL for NAZO (3/15). The median SDMA measured in M1R was 17 µg/dL (15/16), with AZO being 31 µg/dL (3/15), and NAZO being 16.5 µg/dL (12/15); and in M2, SDMA was 12 µg/dL (16/16), with AZO being 12.5 µg/dL (4/16), and NAZO being 12 µg/dL (12/16). The median UPC measured in M1 was 1.15 (10/36), with AZO being 0.25 (1/10), and NAZO being 1.38 (9/10); and in M2, it was 0.2 (13/16), being 0.1 in AZO (4/13), and 0.2 (9/16) in NAZO. For SBP, in M1, it was 118 mmHg (30/36), with AZO being 102 mmHg (10/30) and 133 mmHg in NAZO (20/30); and in M2 142.5 mmHg (12/16), being 155 mmHg for AZO (4/12), and 140 mg/dL for NAZO (8/12). When comparing animals with open and closed cervixes, a difference was found between SDMA measurements (p = .001). There was a distinction between PI and RI of the left and right kidneys consecutively (p = .007; p = .033; p = .019; p = .041). Correlations found in M1: SDMA × PI RIM DIR (r = 0.873; p = .002), SDMA × PSV RIM ESQ (r = 0.840; p = .004), SDMA × EDV RIM ESQ (r = 0.675; p = .046). With this study, we conclude a return to normality of renal biomarkers and clinical parameters after six months. Yet, there is a persistence of Doppler velocimetric measurements between the two moments. Thus, this parameter is not suitable for identifying and classifying chronic kidney injury in bitches with pyometra.

Metabolomic markers mediate erythrocyte anisocytosis in older adults: Results from three independent aging cohorts.

BACKGROUND: Anisocytosis reflects unequal-sized red blood cells and is quantified using red blood cell distribution width (RDW). RDW increases with age and has been consistently associated with adverse health outcomes, such as cardiovascular disease and mortality. Why RDW increases with age is not understood. We aimed to identify plasma metabolomic markers mediating anisocytosis with aging. METHODS: We performed mediation analyses of plasma metabolomics on the association between age and RDW using resampling techniques after covariate adjustment. We analyzed data from adults aged 70 or older from the main discovery cohort of the Baltimore Longitudinal Study of Aging (BLSA, n = 477, 46% women) and validation cohorts of the Health, Aging and Body Composition Study (Health ABC, n = 620, 52% women) and Invecchiare in Chianti, Aging in the Chianti Area (InCHIANTI) study (n = 735, 57% women). Plasma metabolomics was assayed using the Biocrates MxP Quant 500 kit in BLSA and Health ABC and liquid chromatography with tandem mass spectrometry in InCHIANTI. RESULTS: In all three cohorts, symmetric dimethylarginine (SDMA) significantly mediated the association between age and RDW. Asymmetric dimethylarginine (ADMA) and 1-methylhistidine were also significant mediators in the discovery cohort and one validation cohort. In the discovery cohort, we also found choline, homoarginine, and several long-chain triglycerides significantly mediated the association between age and RDW. CONCLUSIONS AND RELEVANCE: This metabolomics study of three independent aging cohorts identified a specific set of metabolites mediating anisocytosis with aging. Whether SDMA, ADMA, and 1-methylhistidine are released by the damaged erythrocytes with high RDW or they affect the physiology of erythrocytes causing high RDW should be further investigated.

SDMA attenuates renal tubulointerstitial fibrosis through inhibition of STAT4.

BACKGROUND: Renal tubulointerstitial fibrosis is the hallmark of various chronic kidney diseases. Symmetric dimethylarginine (SDMA) is an independent cardiovascular risk factor in patients with chronic kidney diseases, which is mostly excreted through renal tubules. However, the effect of SDMA on kidneys in a pathological condition is currently unknown. In this study, we investigated the role of SDMA in renal tubulointerstitial fibrosis and explored its underlying mechanisms. METHODS: Mouse unilateral ureteral obstruction (UUO) and unilateral ischemia-reperfusion injury (UIRI) models were established to study renal tubulointerstitial fibrosis. SDMA was injected into kidneys through ureter retrogradely. TGF-ß stimulated human renal epithelial (HK2) cells were used as an in vitro model and treated with SDMA. Signal transducer and activator of transcription-4 (STAT4) was inhibited by berbamine dihydrochloride or siRNA or overexpressed by plasmids in vitro. Masson staining and Western blotting were performed to evaluate renal fibrosis. Quantitative PCR was performed to validate findings derived from RNA sequencing analysis. RESULTS: We observed that SDMA (from 0.01 to 10 µM) dose-dependently inhibited the expression of pro-fibrotic markers in TGF-ß stimulated HK2 cells. Intrarenal administration of SDMA (2.5 µmol/kg or 25 µmol/kg) dose-dependently attenuated renal fibrosis in UUO kidneys. A significant increase in SDMA concentration (from 19.5 to 117.7 nmol/g, p < 0.001) in mouse kidneys was observed after renal injection which was assessed by LC-MS/MS. We further showed that intrarenal administration of SDMA attenuated renal fibrosis in UIRI induced mouse fibrotic kidneys. Through RNA sequencing analysis, we found that the expression of STAT4 was reduced by SDMA in UUO kidneys, which was further confirmed by quantitative PCR and Western blotting analysis in mouse fibrotic kidneys and renal cells. Inhibition of STAT4 by berbamine dihydrochloride (0.3 mg/ml or 3.3 mg/ml) or siRNA reduced the expression of pro-fibrotic markers in TGF-ß stimulated HK2 cells. Furthermore, blockage of STAT4 attenuated the anti-fibrotic effect of SDMA in TGF-ß stimulated HK2 cells. Conversely, overexpression of STAT4 reversed the anti-fibrotic effect of SDMA in TGF-ß stimulated HK2 cells. CONCLUSION: Taken together, our study indicates that renal SDMA ameliorates renal tubulointerstitial fibrosis through inhibition of STAT4.

Arginine, symmetric and asymmetric dimethylarginine levels in canine leishmaniasis.

The study aimed to investigate the levels of arginine, symmetric dimethylarginine (SDMA), and asymmetric dimethylarginine (ADMA) in dogs with canine leishmaniasis (CanL) and their relationship with some renal and cardiovascular parameters. A total of 60 dogs were enrolled, including 40 with CanL and 20 healthy controls. The CanL group was divided into four stages based on clinical and laboratory findings. The levels of plasma arginine, SDMA, and ADMA were determined by high performance liquid chromatography (HPLC). The data from the healthy group were compared with those from the CanL group, and according to the stages. In dogs with CanL, systolic and diastolic blood pressure, plasma creatinine, cystatin-C, phosphorus, potassium, and low-density lipoprotein concentrations, the urine protein/creatinine ratio, the amount of nitric oxide, and creatine kinase-MB activity were higher, while the high-density lipoprotein concentration was lower compared to healthy controls. The concentration of arginine was low (p < 0.05) and the levels of ADMA (p < 0.001) and SDMA (p < 0.05) were high in dogs with CanL. There were no statistically significant differences in arginine concentration among the different stages of CanL. However, the concentration of plasma ADMA was higher in all stages of CanL compared to the healthy group, and the concentration of plasma SDMA was higher in Stage IV compared to the healthy group and Stage III. The present study demonstrates for the first time a decrease in arginine concentration and an increase in ADMA concentration in dogs with CanL. The increase in SDMA concentration in dogs with CanL was consistent with previous studies. However, compared to other renal parameters, SDMA exhibited limited performance distinguishing between clinical stages of CanL. These findings could be a source for future diagnostic and therapeutic studies to explain the renal and cardiovascular pathophysiology of CanL. Additional clinical studies that include treatment and patient follow-up with an assessment of the acute phase response are needed to provide a more detailed understanding of the changes observed in dogs with CanL.

Altered expression of the L-arginine/nitric oxide pathway in ovarian cancer: metabolic biomarkers and biological implications.

MOTIVATION: Ovarian cancer (OC) is a highly lethal gynecological malignancy. Extensive research has shown that OC cells undergo significant metabolic alterations during tumorigenesis. In this study, we aim to leverage these metabolic changes as potential biomarkers for assessing ovarian cancer. METHODS: A functional module-based approach was utilized to identify key gene expression pathways that distinguish different stages of ovarian cancer (OC) within a tissue biopsy cohort. This cohort consisted of control samples (n = 79), stage I/II samples (n = 280), and stage III/IV samples (n = 1016). To further explore these altered molecular pathways, minimal spanning tree (MST) analysis was applied, leading to the formulation of metabolic biomarker hypotheses for OC liquid biopsy. To validate, a multiple reaction monitoring (MRM) based quantitative LCMS/MS method was developed. This method allowed for the precise quantification of targeted metabolite biomarkers using an OC blood cohort comprising control samples (n = 464), benign samples (n = 3), and OC samples (n = 13). RESULTS: Eleven functional modules were identified as significant differentiators (false discovery rate, FDR < 0.05) between normal and early-stage, or early-stage and late-stage ovarian cancer (OC) tumor tissues. MST analysis revealed that the metabolic L-arginine/nitric oxide (L-ARG/NO) pathway was reprogrammed, and the modules related to "DNA replication" and "DNA repair and recombination" served as anchor modules connecting the other nine modules. Based on this analysis, symmetric dimethylarginine (SDMA) and arginine were proposed as potential liquid biopsy biomarkers for OC assessment. Our quantitative LCMS/MS analysis on our OC blood cohort provided direct evidence supporting the use of the SDMA-to-arginine ratio as a liquid biopsy panel to distinguish between normal and OC samples, with an area under the ROC curve (AUC) of 98.3%. CONCLUSION: Our comprehensive analysis of tissue genomics and blood quantitative LC/MSMS metabolic data shed light on the metabolic reprogramming underlying OC pathophysiology. These findings offer new insights into the potential diagnostic utility of the SDMA-to-arginine ratio for OC assessment. Further validation studies using adequately powered OC cohorts are warranted to fully establish the clinical effectiveness of this diagnostic test.

Urinary excretion of asymmetric (ADMA) and symmetric (SDMA) dimethylarginine is positively related to nitric oxide level in tissues of normotensive and hypertensive rats.

Nitric oxide (NO) is one of the gaseous transmitters which play a very important role in the regulation of the circulatory system. Decreased NO availability is associated with hypertension, cardiovascular and kidney diseases. Endogenous NO is generated enzymatically by nitric oxide synthase (NOS) depending on the availability of the substrate, cofactors, or presence/absence of inhibitors, such as asymmetric dimethylarginine (ADMA) and symmetric dimethylarginine (SDMA). The objective of this study was to evaluate the potential relationship between NO level in rat tissues (heart and kidneys) and the concentrations of endogenous metabolites related to NO in plasma and urine. The experiment was carried out with 16- and 60-week-old male Wistar Kyoto (WKY) and age-matched male Spontaneously Hypertensive Rats (SHR). NO level in tissue homogenates was determined by the colorimetric method. RT-qPCR was used to verify the expression of the eNOS (endothelial NOS) gene. Plasma and urine concentrations of arginine, ornithine, citrulline, and dimethylarginines were examined by the UPLC-MS/MS method. 16-week-old WKY rats had the highest tissue NO and plasma citrulline levels. Furthermore, 16-week-old WKY rats showed higher urinary excretion of ADMA/SDMA compared to other experimental groups, however, plasma concentrations of arginine, ADMA, and SDMA were comparable between the groups. In conclusion, our research shows that hypertension and aging decrease tissue NO levels and are associated with reduced urinary excretion of NOS inhibitors, i.e., ADMA and SDMA.

Plasma arginine metabolites in health and chronic kidney disease.

BACKGROUND: Elevated plasma asymmetric and symmetric dimethylarginine (ADMA and SDMA) are risk factors for chronic kidney disease (CKD) and cardiovascular disease. Using plasma cystatin C (pCYSC)-based estimated glomerular filtration rate (eGFR) trajectories, we identified a cohort at high risk of poor kidney-related health outcomes amongst members of the Dunedin Multidisciplinary Health and Development Study (DMHDS). We therefore examined associations between methylarginine metabolites and kidney function in this cohort. METHODS: ADMA, SDMA, L-arginine and L-citrulline were measured in plasma samples from 45-year-olds in the DMHDS cohort by liquid chromatography-tandem mass spectrometry. RESULTS: In a healthy DMHDS subset (n = 376), mean concentrations were: ADMA (0.40 ± 0.06 µmol/L), SDMA (0.42 ± 0.06 µmol/L), L-arginine (93.5 ± 23.1 µmol/L) and L-citrulline (24.0 ± 5.4 µmol/L). In the total cohort (n = 857), SDMA correlated positively with serum creatinine (Pearson's r = 0.55) and pCYSC (r = 0.55), and negatively with eGFR (r = 0.52). A separate cohort of 38 patients with stage 3-4 CKD (eGFR 15-60 mL/min/1.73 m2) confirmed significantly higher mean ADMA (0.61 ± 0.11 µmol/L), SDMA (0.65 ± 0.25 µmol/L) and L-citrulline (42.7 ± 11.8 µmol/L) concentrations. DMHDS members classified as high-risk of poor kidney health outcomes had significantly higher mean concentrations of all four metabolites compared with individuals not at risk. ADMA and SDMA individually predicted high-risk of poor kidney health outcomes with areas under the ROC curves (AUCs) of 0.83 and 0.84, and together with an AUC of 0.90. CONCLUSIONS: Plasma methylarginine concentrations facilitate stratification for risk of CKD progression.

Pan-methylarginine antibody generation using PEG linked GAR motifs as antigens.

Arginine methylation is a prevalent posttranslational modification which is deposited by a family of protein arginine methyltransferases (PRMTs), and is found in three different forms in mammalian cells: monomethylarginine (MMA), asymmetric dimethylarginine (ADMA) and symmetric dimethylarginine (SDMA). Pan-methylarginine antibodies are critical for identifying proteins that are methylated on arginine residues, and are also used for evaluating signaling pathways that modulate this methyltransferase activity. Although good pan-MMA, -ADMA and -SDMA antibodies have been developed over the years, there is still room for improvement. Here we use a novel antigen approach, which involves the separation of short methylated motifs with inert polyethylene glycol (PEG) linkers, to generate a set of pan antibodies to the full range of methylarginine marks. Using these antibodies, we observed substrate scavenging by PRMT1, when PRMT5 activity is blocked. Specifically, we find that the splicing factor SmD1 displays increased ADMA levels upon PRMT5 inhibitor treatment. Furthermore, when the catalysis of both SDMA and ADMA is blocked with small molecule inhibitors, we demonstrate that SmD1 and SMN no longer interact. This could partially explain the synergistic effect of PRMT5 and type I PRMT inhibition on RNA splicing and cancer cell growth.

Association of Uremic Solutes With Cardiovascular Death in Diabetic Kidney Disease.

RATIONALE & OBJECTIVE: Cardiovascular disease (CVD) is a major cause of mortality among people with diabetic kidney disease (DKD). The pathophysiology is inadequately explained by traditional CVD risk factors. The uremic solutes trimethylamine-N-oxide (TMAO) and asymmetric and symmetric dimethylarginine (ADMA, SDMA) have been linked to CVD in kidney failure with replacement therapy (KFRT), but data are limited in populations with diabetes and less severe kidney disease. STUDY DESIGN: Observational cohort. SETTINGS & PARTICIPANTS: Random subcohort of 555 REGARDS (Reasons for Geographic and Racial Differences in Stroke) study participants with diabetes and estimated glomerular filtration rate (eGFR) <60 mL/min/1.73 m2 at study entry. EXPOSURE: ADMA, SDMA, and TMAO assayed by liquid chromatography-mass spectrometry in plasma and urine. OUTCOME: Cardiovascular mortality (primary outcome); all-cause mortality and incident KFRT (secondary outcomes). ANALYTICAL APPROACH: Plasma concentrations and ratios of urine to plasma concentrations of ADMA, SDMA, and TMAO were tested for association with outcomes. Adjusted Cox regression models were fitted and hazard ratios of outcomes calculated per standard deviation and per doubling, and as interquartile comparisons. RESULTS: The mean baseline eGFR was 44 mL/min/1.73 m2. Cardiovascular death, overall mortality, and KFRT occurred in 120, 285, and 89 participants, respectively, during a mean 6.2 years of follow-up. Higher plasma ADMA and SDMA (HRs of 1.20 and 1.28 per 1-SD greater concentration), and lower ratios of urine to plasma concentrations of ADMA, SDMA, and TMAO (HRs per halving of 1.53, 1.69, and 1.38) were associated with cardiovascular mortality. Higher plasma concentrations of ADMA, SDMA, and TMAO (HRs of 1.31, 1.42, and 1.13 per 1-SD greater concentration) and lower urine to plasma ratios of ADMA, SDMA, and TMAO (HRs per halving of 1.34, 1.37, and 1.26) were associated with all-cause mortality. Higher plasma ADMA and SDMA were associated with incident KFRT by categorical comparisons (HRs of 2.75 and 2.96, comparing quartile 4 to quartile 1), but not in continuous analyses. LIMITATIONS: Single cohort, restricted to patients with diabetes and eGFR < 60 mL/min/1.73 m2, potential residual confounding by GFR, no dietary information. CONCLUSIONS: Higher plasma concentrations and lower ratios of urine to plasma concentrations of uremic solutes were independently associated with cardiovascular and all-cause mortality in DKD. Associations of ratios of urine to plasma concentrations with mortality suggest a connection between renal uremic solute clearance and CVD pathogenesis.

Effects of treatment with SGLT-2 inhibitors on arginine-related cardiovascular and renal biomarkers.

BACKGROUND: In patients with type 2 diabetes (T2D) sodium-glucose cotransporter 2 (SGLT-2) inhibitors improve glycaemic control as well as cardiovascular and renal outcomes. Their effects on L-arginine (Arg) related risk markers asymmetric and symmetric dimethylarginine (ADMA and SDMA) and the protective biomarker L-homoarginine (hArg) linking T2D to cardiovascular and renal disease have not yet been reported. METHODS: Plasma and 24-h urine samples taken before and after 6 weeks of treatment were available from two prospective, randomized, double-blind, placebo-controlled, cross-over trials with empagliflozin (71 patients analyzed, NCT02471963) and dapagliflozin (59 patients analyzed, NCT02383238). In these samples, concentrations of hArg, Arg, ADMA, SDMA, and creatinine were determined by liquid-chromatography coupled to tandem mass-spectrometry. Additionally, intraindividual changes of the biomarkers in plasma were correlated with intraindividual changes of clinical parameters. RESULTS: Treatment with empagliflozin and dapagliflozin was associated with a reduction of plasma hArg by 17.5% and 13.7% (both p < 0.001), respectively, and increase in plasma SDMA concentration of 6.7% and 3.6%, respectively (p < 0.001 and p < 0.05), while plasma Arg and ADMA concentrations were not significantly altered. 24-h urinary excretion of ADMA was reduced by 15.2% after treatment with empagliflozin (p < 0.001) but not after dapagliflozin treatment, while excretion of the other markers was not significantly altered. Renal clearance of SDMA was reduced by 9.1% and 3.9% for both drugs (both p < 0.05). A reduction in ADMA clearance was observable after empagliflozin treatment only (- 15.5%, p < 0.001), but not after dapagliflozin. Renal clearance of hArg and Arg was not significantly altered. Treatment effects on L-arginine related biomarkers were not constantly correlated with effects on glycated hemoglobin, fasting plasma glucose, body mass index, and systolic blood pressure. CONCLUSIONS: Treatment with SGLT-2 inhibitors has divergent effects on Arg-related biomarkers and could affect risk estimates associated with these markers. The observed effects are unlikely to explain the known cardiovascular and renal benefits of treatment with empagliflozin or dapagliflozin but still may indicate new therapeutic approaches in patients treated with SGLT-2 inhibitors. Trial registration http://www.clinicaltrials.gov : NCT02471963 (registered 15th June 2015, retrospectively registered) and NCT02383238.

The Association Between Uric Acid and Symmetric Dimethylarginine Levels in Patients Undergoing Continuous Ambulatory Peritoneal Dialysis.

BACKGROUND: Uric acid (UA) levels are associated with increased risk of cardiovascular events and mortality in hemodialysis (HD) and continuous ambulatory peritoneal dialysis (CAPD) patients. In a study with a population of healthy young adults and HD there was a correlation between high blood uric acid levels and blood symmetric dimethylarginine (SDMA) level. However, in CAPD population, there are still conflicting data on the mechanism of increased risks related to uric acid levels. This study aimed to assess the association between uric acid levels and SDMA in the subjects undergoing CAPD. METHODS: This was a cross - sectional study conducted in all the adults who underwent CAPD for at least three months in tertiary hospital in Jakarta, Indonesia. Subjects already on uric lowering therapy, pregnant or lactating women, and those with a history of malignancy were excluded. Uric acid and SDMA level were measured at the same time patients controlled to outpatient clinic. Bivariate analysis was performed using the Mann - Whitney test and multivariate analysis performed using logistic regression test. RESULTS: A total of 55 subjects were included. The median level of UA was 7.30 + 1.59 mg/dl and 33 subjects (60%) had UA levels of 7 mg/dl or higher. The median SDMA level was 633.73 + 231.54 ng/mL. Subjects with UA levels > 7 mg/dl had significantly higher SDMA levels compared to subjects with UA levels < 7 mg/dl (721.58 + 220.57 vs 501.95 + 182; P < 0.001). The cut - off value of SDMA 536 ng/mL was obtained from the receiver operating characteristic (ROC) curve with sensitivity 81.8%, specificity 63.6%, PPV 77.78% and NPV 73.68%. After fully adjusted with the confounders, the determinant factors in this study were diabetes mellitus (OR: 7.844; CI95%: 1.899 - 32.395: P value: 0.004) and dyslipidemia (OR: 6.440; CI95%: 1.483 - 27.970; P value: 0.013) as risk factors. CONCLUSION: In CAPD patients, UA levels above 7 mg/dl were associated with increased SDMA levels. This study demonstrates the determinant factors regarding association between UA level and SDMA in CAPD patients were diabetes mellitus and dyslipidemia. The cut - off value of SDMA above 536 ng/mL were significant to increased risk of cardiovascular events.

Investigation of oxidative stress in patients with multifocal motor neuropathy.

Background and purpose: Multifocal motor neuropathy (MMN) is a rare, immune-mediated illness attacking ex-clusively motor nerves. It is known that oxidative stress is present in peripheral neuropathies, but it has not been investigated MMN. Methods: We measured in our prospective study the L-arginine, symmetric and asymmetric dimethylarginine (SDMA, ADMA) serum concentrations of 10 patients and 10 controls before and after intravenous immunoglobulin treatment (IVIG), as markers of the L-arginine/NO pathway involved in chronic inflammation and oxidative stress. The functions of motor nerves were tested in all patients and the serum antiganglioside antibody levels were de-tec-ted, as well. Results: MMN patients showed significantly higher ADMA (p = 0.0048; 0.98 and 0.63, respectively) and SDMA le-vels (p = 0.001; 0.88 and 0.51, respectively) than healthy controls, while L-arginine was not different. Controlling for the covariant age, ADMA (B = -0.474; p = 0.041) or SDMA (B = -0.896; p < 0.0005) serum levels proved to be the significant predictors of the presence of MMN. IVIG therapy decreased significantly ADMA concentrations (p = 0.025; 0.98 and 0.84, respectively) and showed a trend to reduce SDMA levels (p = 0.1; 0.88 and 0.74, respectively). The dimethylamine levels did not correlate with the number of affected nerves, disease duration, or the presence of ganglioside antibodies. The conduction block-related peripheral motor dysfunction improved right after the IVIG treatment. Conclusion: Dimethylamine levels are elevated in the serum and are responsive to IVIG therapy in MMN. These findings support the presence of oxidative stress in MMN.

Phosphoserine inhibits neighboring arginine methylation in the RKS motif of histone H3.

The effects of phosphorylation of histone H3 at serine 10 have been studied in the context of other posttranslational modifications such as lysine methylation. We set out to investigate the impact of phosphoserine-10 on arginine-8 methylation. We performed methylation reactions using peptides based on histone H3 that contain a phosphorylated serine and compared the extent of arginine methylation with unmodified peptides. Results obtained via fluorography indicate that peptides containing a phosphorylated serine-10 inhibit deposition of methyl groups to arginine-8 residues. To further explore the effects of phosphoserine on neighboring arginine residues, we physically characterized the non-covalent interactions between histone H3 phosphoserine-10 and arginine-8 using 31P NMR spectroscopy. A salt bridge was detected between the negatively charged phosphoserine-10 and the positively charged unmodified arginine-8 residue. This salt bridge was not detected when arginine-8 was symmetrically dimethylated. Finally, molecular simulations not only confirm the presence of a salt bridge but also identify a subset of electrostatic interactions present when arginine is replaced with alanine. Taken together, our work suggests that the negatively charged phosphoserine maximizes its interactions. By limiting its exposure and creating new contacts with neighboring residues, it will inhibit deposition of neighboring methyl groups, not through steric hindrance, but by forming intrapeptide interactions that may mask substrate recognition. Our work provides a mechanistic framework for understanding the role of phosphoserine on nearby amino acid residues and arginine methylation.

A Review of Specific Biomarkers of Chronic Renal Injury and Their Potential Application in Nonclinical Safety Assessment Studies.

A host of novel renal biomarkers have been developed over the past few decades which have enhanced monitoring of renal disease and drug-induced kidney injury in both preclinical studies and in humans. Since chronic kidney disease (CKD) and acute kidney injury (AKI) share similar underlying mechanisms and the tubulointerstitial compartment has a functional role in the progression of CKD, urinary biomarkers of AKI may provide predictive information in chronic renal disease. Numerous studies have explored whether the recent AKI biomarkers could improve upon the standard clinical biomarkers, estimated glomerular filtration rate (eGFR), and urinary albumin to creatinine ratio, for predicting outcomes in CKD patients. This review is an introduction to alternative assays that can be utilized in chronic (>3 months duration) nonclinical safety studies to provide information on renal dysfunction and to demonstrate specific situations where these assays could be utilized in nonclinical drug development. Novel biomarkers such as symmetrical dimethyl arginine, dickkopf homolog 3, and cystatin C predict chronic renal injury in animals, act as surrogates for GFR, and may predict changes in GFR in patients over time, ultimately providing a bridge from preclinical to clinical renal monitoring.

Assessment of potential cardiovascular risk in trichloroethylene exposure by serum methylated arginine levels.

Trichloroethylene (TCE) is a widely used solvent in industrial applications and has toxic effects on various systems. Methylated arginine amino acids (eg asymmetric dimethyl arginine (ADMA), symmetric dimethyl arginine (SDMA)) cause the development of cardiovascular disease by inhibiting NO synthesis, which is considered to be heart-protector. The aim of this study is to determine the risk of cardiovascular diseases in TCE exposure by methylated arginine biomarkers. About 98 controls and 100 TCE-exposed male subjects were included in the study. Trichloroacetic acid (urinary metabolite of TCE), arginine, homoarginine, citrulline ADMA, SDMA, and N-monomethyl L-arginine (L-NMMA) levels were found significantly higher than control group (p < 0.001). The strongest correlation was found between ADMA and Trichloroacetic acid (TCA) level (r = 0.453, p < 0.01). Long-term TCE exposure, may be an important risk factor for cardiovascular diseases by increasing methylated arginine levels.

Improved Discrimination of Asymmetric and Symmetric Arginine Dimethylation by Optimization of the Normalized Collision Energy in Liquid Chromatography-Mass Spectrometry Proteomics.

Protein arginine methylation regulates diverse biological processes including signaling, metabolism, splicing, and transcription. Despite its important biological roles, arginine dimethylation remains an understudied post-translational modification. Partly, this is because the two forms of arginine dimethylation, asymmetric dimethylarginine (ADMA) and symmetric dimethylarginine (SDMA), are isobaric and therefore indistinguishable by traditional mass spectrometry techniques. Thus, there exists a need for methods that can differentiate these two modifications. Recently, it has been shown that the ADMA and SDMA can be distinguished by the characteristic neutral loss (NL) of dimethylamine and methylamine, respectively. However, the utility of this method is limited because the vast majority of dimethylarginine peptides do not generate measurable NL ions. Here, we report that increasing the normalized collision energy (NCE) in a higher-energy collisional dissociation cell increases the generation of the characteristic NLs that distinguish ADMA and SDMA. By analyzing both synthetic and endogenous methyl-peptides, we identify an optimal NCE value that maximizes NL generation and simultaneously improves methyl-peptide identification. Using two orthogonal methyl-peptide enrichment strategies, high pH strong cation-exchange and immunoaffinity purification, we demonstrate that the optimal NCE improves NL-based ADMA and SDMA annotation and dimethyl-peptide identifications by 125% and 17%, respectively, compared to the standard NCE. This simple parameter change will greatly facilitate the identification and annotation of ADMA and SDMA in mass spectrometry-based methyl-proteomics to improve our understanding of how these modifications differentially regulate protein function. All raw data have been deposited in the PRIDE database with accession number PXD017193.

Comprehensive arginine metabolomics and peripheral vasodilatory capacity in rheumatoid arthritis: A monocentric cross-sectional study.

BACKGROUND: The relationship between plasma arginine metabolites influencing vascular homeostasis and peripheral vasodilatory capacity in rheumatoid arthritis (RA) patients is not known. METHODS: l-arginine (Arg), monomethyl-l-arginine (MMA), l-homoarginine (hArg), asymmetric dimethyl-l-arginine (ADMA), symmetric dimethyl-l-arginine, and l-citrulline (Cit) were measured by liquid chromatography tandem mass spectrometry (LC-MS/MS) in 164 RA patients and 100 age- and sex-matched healthy controls without previous cardiovascular events. Log-transformed reactive hyperemia index (Ln-RHI) evaluated by flow-mediated pulse amplitude tonometry (PAT, EndoPAT2000 device) was assessed as surrogate measure of peripheral vasodilatory capacity in RA patients. Ln-RHI values <0.51 indicated peripheral endothelial dysfunction (ED). The relationship between plasma arginine metabolite concentrations, RA descriptors and peripheral vasodilatory capacity was evaluated by bivariate correlation and regression analyses. RESULTS: Plasma ADMA concentrations were significantly higher, and plasma hArg concentrations significantly lower, in RA patients than in controls (0.53 ± 0.09 vs 0.465 ± 0.07 µmol/L and 1.50 ± 0.60 vs 1.924 ± 0.78 µmol/L, respectively; p < 0.001 for both comparisons). Bivariate correlation analysis demonstrated no significant correlation between arginine metabolites and disease descriptors. In regression analysis in RA patients, higher plasma ADMA concentrations were independently associated with presence of ED [OR(95% CI) = 77.3(1.478-4050.005), p = 0.031] and lower Ln-RHI [B coefficient(95% CI) = -0.57(-1.09 to -0.05), p = 0.032]. CONCLUSIONS: ADMA was significantly, albeit weakly, associated with impaired microcirculatory vasodilatory capacity and peripheral endothelial dysfunction in RA. This suggests an important pathophysiological role of this metabolite in the vascular alterations observed in this patient group.

Drugs linked to plasma homoarginine in chronic kidney disease patients-a cross-sectional analysis of the German Chronic Kidney Disease cohort.

BACKGROUND: Elevated plasma concentrations of symmetric and asymmetric dimethylarginine (SDMA and ADMA, respectively) and a lower plasma concentration of the structurally related homoarginine are commonly observed in patients with chronic kidney disease (CKD) and independently predict total mortality as well as progression of renal disease. We aimed to identify drugs that may alter this adverse metabolite pattern in a favourable fashion. METHODS: Plasma ADMA, SDMA, homoarginine and l-arginine were determined by liquid chromatography-tandem mass spectrometry in 4756 CKD patients ages 18-74 years with an estimated glomerular filtration rate (eGFR) of 30-60 mL/min/1.73 m2 or an eGFR >60 mL/min/1.73 m2 and overt proteinuria who were enrolled in the German Chronic Kidney Disease (GCKD) study. Associations between laboratory, clinical and medication data were assessed. RESULTS: Intake of several commonly used drugs was independently associated with plasma concentrations of homoarginine and/or related metabolites. Among these, the peroxisome proliferator-activated receptor alpha (PPAR-α) agonist fenofibrate was associated with the most profound differences in ADMA, SDMA and homoarginine plasma concentrations: 66 patients taking fenofibrate had a multivariable adjusted odds ratio (OR) of 5.83 [95% confidence interval (CI) 2.82-12.03, P < 0.001] to have a plasma homoarginine concentration above the median. The median homoarginine plasma concentration in patients taking fenofibrate was 2.30 µmol/L versus 1.55 in patients not taking the drug (P < 0.001). In addition, fibrates were significantly associated with lower plasma SDMA and higher l-arginine concentrations. In contrast, glucocorticoids were associated with lower plasma homoarginine, with adjusted ORs of 0.52 (95% CI 0.40-0.67, P < 0.001) and 0.53 (95% CI 0.31-0.90, P = 0.018) for prednisolone and methylprednisolone, respectively. CONCLUSIONS: In a large cohort of CKD patients, intake of fenofibrate and glucocorticoids were independently associated with higher and lower plasma homoarginine concentrations, respectively. Effects on plasma homoarginine and methylarginines warrant further investigation as potential mechanisms mediating beneficial or adverse drug effects.