Plasma Cysteine Research Articles

A Hydrogen Bonded Non-Porous Organic-Inorganic Framework for Measuring Cysteine in Blood Plasma and Endogenous Cancer Cell.

An imbalance in cysteine (Cys) levels in the cells and plasma has been identified as the risk indicator for various human diseases. The structural similarity of cysteine with its congener homocysteine and glutathione offers challenges in its measurement. Herein, we report a hydrogen-bonded organic-inorganic framework of Cu(II) (HOIF) for the selective detection of cysteine over other biothiols. The non-fluorescent HOIF showed 12-fold green emission in the presence of cysteine. The monomeric unit of HOIF is stabilized via intermolecular hydrogen bonds, resulting in a non-porous network structure. Non-interference from homocysteine, glutathione, and other competitive bio-analytes revealed explicit affinity of HOIF for cysteine. Fluorimetric titration showed a wide working concentration window (650 nM-800 μM) for measuring cysteine in an aqueous medium. The mechanistic investigation involving HRMS, EPR, and UV-vis spectroscopic studies revealed the decomplexation of HOIF with Cys, resulting in a fluorescence turn-on response from the luminescent ligand. Validation using a commercial dye, "Cysteine Green", confirmed the prospect of HOIF for early diagnostic purposes. Utilizing the fluorescence turn-on property of HOIF in the presence of cysteine, we measured cysteine quantitatively in the blood plasma samples. Bio-imaging of endogenous cysteine in cancer cells indicated the ability of HOIF to monitor the intracellular cysteine.

Impact of homocysteine on acute ischemic stroke severity: possible role of aminothiols redox status

BackgroundAcute ischemic stroke (AIS) is one of the most common cerebrovascular diseases which accompanied by a disruption of aminothiols homeostasis. To explore the relationship of aminothiols with neurologic impairment severity, we investigated four aminothiols, homocysteine (Hcy), cysteine (Cys), cysteinylglycine (CG) and glutathione (GSH) in plasma and its influence on ischemic stroke severity in AIS patients.MethodsA total of 150 clinical samples from AIS patients were selected for our study. The concentrations of free reduced Hcy (Hcy), own oxidized Hcy (HHcy), free reduced Cys (Cys), own oxidized Cys (cysteine, Cyss), free reduced CG (CG) and free reduced GSH (GSH) were measured by our previously developed hollow fiber centrifugal ultrafiltration (HFCF-UF) method coupled with high performance liquid chromatography-tandem mass spectrometry (HPLC-MS/MS). The concentration ratio of Hcy to HHcy (Hcy/HHcy), Cys to Cyss (Cys/Cyss) were also calculated. The neurologic impairment severity of AIS was evaluated using National Institutes of Health Stroke Scale (NIHSS). The Spearman correlation coefficient and logistic regression analysis was used to estimate and perform the correlation between Hcy, HHcy, Cys, Cyss, CG, GSH, Hcy/HHcy, Cys/Cyss and total Hcy with NIHSS score.ResultsThe reduced Hcy and Hcy/HHcy was both negatively correlated with NIHSS score in AIS patients with P = 0.008, r=-0.215 and P = 0.002, r=-0.249, respectively. There was no significant correlation of Cys, CG, GSH, HHcy, Cyss, Cys/Cyss and total Hcy with NIHSS score in AIS patients with P value > 0.05.ConclusionsThe reduced Hcy and Hcy/HHcy, not total Hcy concentration should be used to evaluate neurologic impairment severity of AIS patient.

Effect of Dietary Protein Intake from Different Sources on Maternal and Umbilical Cord Plasma Amino Acid Levels.

To assess the associations of dietary protein intake from different sources during pregnancy with maternal and umbilical cord plasma amino acid levels. The study includes 216 pregnant women and 39 newborns from the Tongji Birth Cohort in Wuhan, China. The study examines the levels of 21 amino acids in maternal and cord plasma samples using ultra-performance liquid chromatography with tandem mass spectrometry. A significant positive relationship is observed between dietary protein intake from refined grains and maternal plasma cysteine levels. Dietary protein intake from dairy products is positively associated with maternal plasma levels of sulfur amino acid (mainly cystine), but negatively associated with maternal plasma levels of glutamic acid. In addition, the study observes that pre-pregnancy body mass index and parity may be potential determinants of maternal plasma amino acid levels, whereas a history of passive smoking during pregnancy is an important factor influencing cord plasma amino acid levels. These findings suggest that dietary protein intakes from specific sources during pregnancy may affect maternal plasma levels of amino acids.

Simultaneous determination of cystine and other free aminothiols in blood plasma using capillary electrophoresis with pH-mediated stacking.

We developed a method of sensitive capillary electrophoresis using UV detection for the determination of certain free aminothiols (reduced cysteinylglycine (rCysGly), cysteine (rCys), glutathione (rGln), and cystine (CysS) in human blood plasma. The reduced thiols were derivatized with N-ethylmaleimide. The plasma was purified from proteins via ultrafiltration. Electrophoretic separation was performed using 115mM Na phosphate with 7.5% (v/v) polyethylene glycol 600, pH 2.3. The in-capillary concentration of the analytes was achieved with a pH gradient created via the preinjection of triethanolamine and postinjection of phosphoric acid. The separation was carried out using a silica capillary (50µm i.d.; total/effective separation length 42/35cm) at a 25kV voltage. The total analysis/regeneration time was 18min. The quantification limits varied from 1.3µM (rCysGly) to 5.4µM (CysS). The accuracy was 95%-99%, and the repeatability and reproducibility were approximately 1.8%-3.8% and 1.9%-5.0%, respectively. An analysis of plasma samples from healthy volunteers (N=41) showed that the mean levels of rCysGly, rCys, rGln, and CysS were 1.64, 10.6, 2.58, and 46.2µM, respectively.

SAR of L-ABBA analogs for GGT1 inhibitory activity and L-ABBA's effect on plasma cysteine and GSH species

Gamma-glutamyl transferase 1 (GGT1) is a critical enzyme involved in the hydrolysis and/or transfer of gamma-glutamyl groups of glutathione, which helps maintain cysteine levels in plasma. In this study, we synthesized L-ABBA analogs to investigate their inhibitory effect on GGT1 hydrolysis and transpeptidase activity, with the goal of defining the pharmacophore of L-ABBA. Our structure–activity relationship (SAR) study revealed that an α-COO- and α-NH3+ group, as well as a two-CH2 unit distance between α-C and boronic acid, are essential for the activity. The addition of an R (alkyl) group at the α-C reduced the activity of GGT1 inhibition, with L-ABBA being the most potent inhibitor among the analogs. Next, we investigated the impact of L-ABBA on plasma levels of cysteine and GSH species, with the expectation of observing reduced cysteine levels and enhanced GSH levels due to its GGT1 inhibition. We administered L-ABBA intraperitoneally and determined the plasma levels of cysteine, cystine, GSH, and GSSG using LCMS. Our results showed time- and dose-dependent L-ABBA changes in total plasma cysteine and GSH levels. This study is the first to demonstrate the regulation of plasma thiol species upon GGT1 inhibition, with plasma cystine levels reduced by up to ∼ 75 % with L-ABBA (0.3 mg/dose). Cancer cells are highly dependent on the uptake of cysteine from plasma for maintaining high levels of intracellular glutathione. Thus, our findings suggest that GGT1 inhibitors, such as L-ABBA, have the potential to be used in GSH reduction thereby inducing oxidative stress in cancer cells and reducing their resistance to many chemotherapeutic agents.

REVERSED PHASE HPLC DETERMINATION OF TOTAL HOMOCYSTEINE, CYSTEINE, CYSTEINYL GLYCINE, GLUTATHIONE IN PLASMA OF EPILEPTIC PATIENTS

The fast and accurate reversed-phase HPLC method was predicated on qualitative and quantitative estimation of the total concentrations of the essential thiols in the plasma of adults volunteers compared with epileptic patients, which is l-cysteine (Cys) total homocysteine (tHys), cysteinyl glycine (Cys-Gly), glutathione (GSH) and cysteamine (Cstm), respectively. The plasma samples of (50) epileptic patients were classified into three groups; the non-anti-epileptic drug consisted of 20 patients (12 male, eight female) who were mainly diagnosed with idiopathic generalized epilepsy. The mean age was 34 ± 13 (range 19–48) years. The second group consisted of 30 patients receiving two types of anti-epileptic drugs, 18 patients (12 male and six female) receiving Carbamazepine, and 12 patients (7 males and five female) receiving phenytoin. The mean age of the patients was 32 ± 11 Compared with 31 healthy volunteers (20 male and 11 female). The mean age of the controls was 31 ± 9 (range 26–49 years). The mean duration of treatment of patients receiving the anti-epileptic drug was six months). All measurement was done using pre-column derivatization with bromobimane, and the derivative of each standard mixture were baseline separated on C18-DB (50 x 4.6 mm ID) column, 3μm particle size. The regression coefficients for the separated and standard deviation SD within-run ranged from 0.09 to 8.40 μmol/L, and between-run ranged from 0.15to 9.16 μmol/L; the analytical procedure gave good linearity in the range between 1.25 to 20 µmole/ l, the detection limit was 0.1 µmole /L for all the thiol groups. Analytical recovery was 96.9–107.4 %; the mean concentration of plasma cysteine and total homocysteine was slightly higher in males than females; it was 221± 75 for adult males and 190± 44 μmol/L for adult females, while t-homocysteine was (10.55 ±2.45 vs. 9.79 ± 1.88 μmol/L, the results observed that the value of cysteine and homocysteine were significantly higher in epileptic patients using Carbamazepine and phenytoin than in healthy volunteers. Mean values for glutathione were lower, while cysteinyl glycine showed no significant difference in healthy and epileptic patients and no sex- and age-dependent.

СЕРОСОДЕРЖАЩИЕ АМИНОКИСЛОТЫ И РИСК РАЗВИТИЯ АРТЕРИАЛЬНОЙ ГИПЕРТЕНЗИИ У ДЕТЕЙ

Introduction. Currently, sulfur-containing amino acids are potential candidates as risk factors for cardiovascular disease. The purpose: to establish the role of sulfur-containing amino acids and their derivatives in the risk of developing arterial hypertension in children. Matherial and methods. 111 children aged 14 to 18 years were examined. All patients were divided into 3 groups: the 1st group (n=51) consisted of children with arterial hypertension, the 2nd group (n=30) – with high normal blood pressure, the 3rd group – 30 healthy children. The content of sulfur-containing amino acids and their derivatives in blood plasma was determined by high-performance liquid chromatography. Result. The concentration of sulfur-containing amino acids methionine, homocysteine, cysteine and cysteinylglycine in the blood plasma of children with arterial hypertension tend to increase in comparison with the group of healthy children. Pathological decrease in endothelium-dependent vasodilation accompanied by an increase in the concentration of methionine, homocysteine, cysteine, cysteinylglycine, glutathione in blood plasma and a decrease – taurine. A prognostic model has been developed based on the determination of the concentration of homocysteine and cysteinylglycine in the blood plasma of children. With a calculated value of p≥0,44, makes it possible to predict a high probability of arterial hypertension with a sensitivity of 90,2%, a specificity of 66,7% and a diagnostic efficiency of 82,1%. Conclusions. The concentration of sulfur-containing amino acids methionine, homocysteine, cysteine and cysteinylglycine in the blood plasma of children with arterial hypertension tend to increase in comparison with the group of healthy children.

Potential mechanism for hyperhomocysteinemia in Greyhound dogs.

Greyhounds have been reported to have hyperhomocysteinemia (HHC), but the underlying mechanisms and clinical implications are unclear. Our primary aim was to assess serum concentrations of homocysteine (HCy) and related analytes in Greyhounds and to identify a likely metabolic pathway for HHC. A secondary aim was to determine whether HHC is associated with evidence of oxidative stress. Healthy pet Greyhounds (n = 31) and non-sighthound control dogs (n = 15). Analysis of serum HCy, cobalamin, folate, and methionine, and plasma cysteine, glutathione, and total 8-isoprostane concentrations. Homocysteine concentrations were higher in Greyhounds (median, 25.0 μmol/L) compared to controls (13.9 μmol/L; P < .0001). Cobalamin concentrations were lower in Greyhounds (median, 416 ng/L) compared to controls (644 ng/L; P = .004) and were inversely correlated with HCy (r = -0.40, P = .004). Serum concentrations of folate, which is regenerated when HCy is converted to methionine, also were inversely correlated with HCy (r = -0.47, P = .002). Serum methionine concentrations were more than 4-fold lower in Greyhounds (median, 3.2 μmol/L) compared to controls (median, 15.0 μmol/L), but this difference was not significant (P = .3). Plasma cysteine, glutathione, and 8-isoprostane concentrations did not differ significantly between groups. Our findings suggest a primary defect in conversion of HCy to methionine in Greyhounds, with related impaired folate generation. Ineffective cycling by methionine synthase could lead to secondary cobalamin depletion. Notably, low serum folate and cobalamin concentrations can be observed in Greyhounds without signs of intestinal disease.

Cysteine restriction-specific effects of sulfur amino acid restriction on lipid metabolism.

Decreasing the dietary intake of methionine exerts robust anti-adiposity effects in rodents but modest effects in humans. Since cysteine can be synthesized from methionine, animal diets are formulated by decreasing methionine and eliminating cysteine. Such diets exert both methionine restriction (MR) and cysteine restriction (CR), that is, sulfur amino acid restriction (SAAR). Contrarily, SAAR diets formulated for human consumption included cysteine, and thus might have exerted only MR. Epidemiological studies positively correlate body adiposity with plasma cysteine but not methionine, suggesting that CR, but not MR, is responsible for the anti-adiposity effects of SAAR. Whether this is true, and, if so, the underlying mechanisms are unknown. Using methionine- and cysteine-titrated diets, we demonstrate that the anti-adiposity effects of SAAR are due to CR. Data indicate that CR increases serinogenesis (serine biosynthesis from non-glucose substrates) by diverting substrates from glyceroneogenesis, which is essential for fatty acid reesterification and triglyceride synthesis. Molecular data suggest that CR depletes hepatic glutathione and induces Nrf2 and its downstream targets Phgdh (the serine biosynthetic enzyme) and Pepck-M. In mice, the magnitude of SAAR-induced changes in molecular markers depended on dietary fat concentration (60% fat >10% fat), sex (males > females), and age-at-onset (young > adult). Our findings are translationally relevant as we found negative and positive correlations of plasma serine and cysteine, respectively, with triglycerides and metabolic syndrome criteria in a cross-sectional epidemiological study. Controlled feeding of low-SAA, high-polyunsaturated fatty acid diets increased plasma serine in humans. Serinogenesis might be a target for treating hypertriglyceridemia.

A high-performance fluorescent probe for detection of cysteine in plasma constructed by combining Cu(I) and 2,5-dimercapto-1,3,4-thiadiazole

A high-performance fluorescent probe 2,5-dimercapto-1,3,4-thiadiazole copper nanoparticles (DMTD-CuNPs) was synthesized by hydrothermal method based on monovalent copper (Cu(I)) and 2,5-dimercapto-1,3,4-thiadiazole (DMTD), and it can effectively detect cysteine (Cys) in plasma. Experiments show that DMTD can reduces band gap of Cu(I) in DMTD-CuNPs, promote charge transfer transition from DMTD to Cu(I) and significantly enhance fluorescence intensity of DMTD-CuNPs at 515 nm. The large Stokes shift of DMTD-CuNPs is 315 nm, which can reduce the self-quenching of probe fluorescence and improves detection accuracy of the probe. In the presence of Cys, fluorescence of DMTD-CuNPs at 515 nm is significantly quenched because Cys reacts with Cu(I) in DMTD-CuNPs through Cu-S bond to form reduced charge transfer, which can be successfully used for the detection of Cys. Linear range and detection limit for Cys detection are 25–65 µM and 50 nM, respectively. Furthermore, feasibility of detecting Cys in plasma using DMTD-CuNPs probe was evaluated by standard addition method, and the absolute recovery is 96–99%. Such a DMTD-CuNPs probe shows high sensitivity, good selectivity and low detection limit for Cys, which is expected to be used for the practical analysis of Cys in plasma.

Cysteine Regulates Oxidative Stress and Glutathione-Related Antioxidative Capacity before and after Colorectal Tumor Resection

Cysteine might scavenge free radicals and is a limiting substrate for the cellular synthesis of glutathione (GSH). We investigated the association of cysteine with oxidative stress and GSH-related antioxidant capacity in colorectal cancer (CRC) patients. Plasma samples were drawn from 66 patients 1 day before (pre-resection) and 4 weeks after resection (post-resection). Tumor and adjacent normal tissues were collected. We measured levels of plasma and tissue cysteine, homocysteine, oxidative stress indicators (malondialdehyde, MDA; advanced oxidation protein products, AOPP), GSH, and antioxidant enzyme activities. After tumor resection, patients had significantly higher levels of plasma cysteine, homocysteine, MDA, AOPP, and GSH-related antioxidant enzyme activities when compared with pre-resection. Levels of cysteine, homocysteine, AOPP and all antioxidant capacity indicators in tumor tissue were significantly higher than those levels in the adjacent normal tissue. Plasma cysteine levels measured at pre-resection were positively associated with MDA levels in the tumor and in the adjacent normal tissues. Cysteine levels in tumor and adjacent normal tissues were significantly associated with tissue levels of homocysteine, almost as indicators of oxidative stress and antioxidant capacities. Cysteine in the circulation was likely utilized to mediate GSH-related antioxidant capacity and further cope with increased oxidative stress in tumor and adjacent normal tissues.

Differential expression of cystathionine beta synthase in adolescents with Down syndrome: impact on adiposity.

Obesity is more prevalent among people with Down Syndrome (DS) compared to general population. In this pilot study, we investigated the effect of cystathionine beta-synthase (CBS) overdosage on the regulation of transsulfuration pathway and the obesity phenotype in fifty adolescents (25 obese/overweight and 25 lean) with trisomy 21. The transcriptional levels of CBS in leukocytes and its translational levels in plasma were quantified using real time polymerase chain reaction and enzyme-linked immunosorbent assay respectively. Meanwhile, ultra performance liquid chromatography tandem mass spectrometry was used to determine the plasma concentrations of methionine, homocysteine, cystathionine and cysteine. Fasting plasma lipid profiles were assessed by colorimetric assays. The anthropometric measurements and indices of all subjects were recorded. Both DS groups had comparable levels of CBS transcripts (p = 0.2734). The plasma levels of the enzyme were significantly higher in the lean DS cases (p = 0.0174) compared to the obese/overweight participants. Total cholesterol, triglycerides, high-density lipoprotein, low-density lipoprotein, methionine, homocysteine, cystathionine and cysteine showed similar plasma levels in both groups. However, the plasma cysteine levels exceeded the normal range in all DS cases. We reported a statistically significant inverse association between CBS enzyme levels and weight (r= - 0.3498, p = 0.0128), hip circumference (r= - 0.3584, p = 0.0106), body mass index (r= - 0.3719, p = 0.0078) and body adiposity index (r= - 0.3183, p = 0.0243). Our data suggests that the high concentrations of CBS enzyme together with cysteine modulate the DS obesity presumably through increased hydrogen sulfide production which has recently showed anti-adiposity effects.

52 Weaning Elicits a Distinct Increase in Plasma Cysteine Concentration in Pigs

Abstract Weaning is a stressful event in pigs that is associated with low and variable feed intake, poor nutrient utilization, and high feed costs. The sulfur amino acids (SAA) methionine and cysteine have key roles in pig production, but how SAA metabolism, and thus SAA requirements, is affected by weaning is poorly understood. The objective of this study was to determine weaning-induced changes in SAA metabolism. Pigs (initial BW = 7,233 ± 683 g) were either weaned at 21 d age and euthanized at 23 d age (n = 4) or remained with the sow and euthanized at 23 d age (n = 4). Weaned pigs were fasted but had free access to water. At euthanasia, blood and liver tissue were collected. Plasma amino acids and amino thiols were analyzed by HPLC following pre-column derivatization with 6-aminoquinolyl-N-hydroxysuccinimidyl carbamate and 4-fluoro-7-aminosulfonylbenzofurazan, respectively. The protein abundance of cystathionine β-synthase (CBS) and cystathionine γ-lyase (CTH), enzymes needed for methionine transsulfuration to cysteine, in liver were determined by Western blot. Total plasma non-essential amino acid (NEAA) concentrations declined in weaned compared with unweaned pigs (2,664 versus 4,290 ± 211 µmol/L, P &amp;lt; 0.01). Among NEAA, however, only plasma cysteine concentration increased in weaned compared with unweaned pigs (total cysteine, 253 versus 173 ± 16 µmol/L, P &amp;lt; 0.05; cystine, 43 versus 23 ± 5 µmol/L, P &amp;lt; 0.05). Plasma methionine tended to be less in weaned pigs (53 versus 65 ± 4 µmol/L, P = 0.075), whereas plasma taurine was less in weaned pigs (64 versus 128 ± 10 µmol/L, P &amp;lt; 0.01). The abundance of CBS and CTH protein in liver was not different between groups. Elevated plasma cysteine concentrations after weaning in pigs is likely due to decreased cysteine oxidation to taurine rather than greater methionine transsulfuration to cysteine.

Associations between Genetic Variants and Blood Biomarkers of One-Carbon Metabolism in Postmenopausal Women from the Women's Health Initiative Observational Study

Genetic variation in one-carbon metabolism may affect nutrient concentrations and biological functions. However, data on genetic variants associated with blood biomarkers of one-carbon metabolism in US postmenopausal women are limited, and whether these associations were affected by the nationwide folic acid (FA) fortification program is unclear. We investigated associations between genetic variants and biomarkers of one-carbon metabolism using data from the Women's Health Initiative Observational Study. In 1573 non-Hispanic White (NHW) and 282 Black/African American, American Indian/Alaska Native, Asian/Pacific Islander, and Hispanic/Latino women aged 50-79 y, 288 nonsynonymous and tagging single-nucleotide variants (SNVs) were genotyped. RBC folate, plasma folate, pyridoxal-5'-phosphate (PLP), vitamin B-12, homocysteine, and cysteine concentrations were determined in 12-h fasting blood. Multivariable linear regression tested associations per variant allele and for an aggregated genetic risk score. Effect modifications before, during, and after nationwide FA fortification were examined. After correction for multiple comparisons, among NHW women, 5,10-methylenetetrahydrofolate reductase (MTHFR) rs1801133 (677C→T) variant T was associated with lower plasma folate (-13.0%; 95% CI: -17.3%, -8.6%) and higher plasma homocysteine (3.5%; 95% CI: 1.7%, 5.3%) concentrations. Other associations for nonsynonymous SNVs included DNMT3A rs11695471 (T→A) with plasma PLP; EHMT2 rs535586 (G→A), TCN2 rs1131603 (L349S A→G), and TCN2 rs35838082 (R188W G→A) with plasma vitamin B-12; CBS rs2851391 (G→A) with plasma homocysteine; and MTHFD1 rs2236224 (G→A) and rs2236225 (R653Q G→A) with plasma cysteine. The influence of FA fortification on the associations was limited. Highest compared with lowest quartiles of aggregated genetic risk scores from SNVs in MTHFR and MTRR were associated with 14.8% to 18.9% lower RBC folate concentrations. Gene-biomarker associations were similar in women of other races/ethnicities. Our findings on genetic variants associated with several one-carbon metabolism biomarkers may help elucidate mechanisms of maintaining B vitamin status in postmenopausal women.

A High-Performance Fluorescent Biosensor for Detection of Cysteine in Plasma Constructed by Combining Cu(I) and 2,5-Dimercapto-1,3,4-Thiadiazole

A High-Performance Fluorescent Biosensor for Detection of Cysteine in Plasma Constructed by Combining Cu(I) and 2,5-Dimercapto-1,3,4-Thiadiazole

Extracellular cystine influences human preadipocyte differentiation and correlates with fat mass in healthy adults

Plasma cysteine is associated with human obesity, but it is unknown whether this is mediated by reduced, disulfide (cystine and mixed-disulfides) or protein-bound (bCys) fractions. We investigated which cysteine fractions are associated with adiposity in vivo and if a relevant fraction influences human adipogenesis in vitro. In the current study, plasma cysteine fractions were correlated with body fat mass in 35 adults. Strong positive correlations with fat mass were observed for cystine and mixed disulfides (r ≥ 0.61, P < 0.001), but not the quantitatively major form, bCys. Primary human preadipocytes were differentiated in media containing cystine concentrations varying from 10–50 μM, a range similar to that in plasma. Increasing extracellular cystine (10–50 μM) enhanced mRNA expression of PPARG2 (to sixfold), PPARG1, PLIN1, SCD1 and CDO1 (P = 0.042– < 0.001). Adipocyte lipid accumulation and lipid-droplet size showed dose-dependent increases from lowest to highest cystine concentrations (P < 0.001), and the malonedialdehyde/total antioxidant capacity increased, suggesting increased oxidative stress. In conclusion, increased cystine concentrations, within the physiological range, are positively associated with both fat mass in healthy adults and human adipogenic differentiation in vitro. The potential role of cystine as a modifiable factor regulating human adipocyte turnover and metabolism deserves further study.

The Effect of Fermentation of High- or Low-Tannin Fava Bean on Glucose Tolerance, Body Weight, Cardiovascular Function, and Blood Parameters in Dogs After 7 Days of Feeding: Comparison With Commercial Diets With Normal vs. High Protein.

Fava bean, which is available in high- and low-tannin varieties, is not an approved pet food ingredient and was not included in the “assumed to be safe” category based on its ability to cause favism and hemolytic anemia in susceptible humans. The effects of 7-day feeding of test canine diets containing moderate protein (~27%) were compared with two control commercial diets with normal (NP, grain-containing, ~25% protein) or high protein (HP, grain-free, ~41% protein). Fava bean diets were formulated either with or without Candida utilis fermentation processing to reduce antinutritional factors. Glucose tolerance, body weight, cardiovascular function, and blood parameters were investigated in beagles fed the NP or HP diets or a randomized, crossover, 2 × 2 Latin square design of the fava bean diets: unfermented high-tannin (UF-HT), fermented high-tannin (FM-HT), unfermented low-tannin (UF-LT), and fermented low-tannin (FM-LT). After 7 days, HP decreased red blood cells (RBC) (P < 0.05) compared with NP, while FM increased RBC compared with UF. HP increased blood bicarbonate, calcium, phosphorus, urea, cholesterol, and albumin:globulin ratio while decreasing bilirubin, liver enzymes, and total protein. Sodium:potassium ratio was increased in UF-HT, decreased in FM-HT, and intermediate in LT regardless of fermentation. Blood phosphorus was increased in HT. Blood amylase was increased in FM-HT and decreased in FM-LT, being intermediate in UF regardless of fava bean variety. Blood direct bilirubin was decreased in HT regardless of fermentation. Of note, left ventricular end-systolic volume and cardiac output were increased in NP compared with HP-fed dogs, but were normal and had no significant differences among the fava bean diets. As expected, plasma taurine, cystine, and cysteine levels were increased in HP- compared with NP-fed dogs. Plasma cysteine levels were increased in HT- compared with LT-fed dogs and in FM- compared with UF-fed dogs. Taken together, these results show that fava bean appears to be safe as a dog food ingredient at least in the short term, and its nutritional value appears improved by fermentation. Moreover, blood chemistry parameters and cardiovascular function were impacted by protein content which merits further investigation with longer term feeding trials.

Biothiol modulated growth and aggregation of gold nanoparticles and their determination in biological fluids using digital photometry

This work describes a novel and easy to use method for the determination of biologically important thiols that relies on their ability to inhibit the catalytic enlargement of AuNP seeds in the presence of ACl4− ions and trigger their aggregation. UV–vis spectroscopic monitoring of the plasmon resonance bands of the formed AuNPs showed that the spectral and color transitions depend both on the concentration and the structure of biothiols. The colorimetric changes induced by biothiols were quantified in the concentration range from 5 to 300 μM in the RGB color system with digital photometry using a commercially available flatbed scanner as detector. On the basis of these results, the applicability of the method was tested to the determination of glutathione in red blood cells and cysteine in blood plasma with satisfactory recoveries (88.7–96.5%), low detection limits (1.0 μM), good selectivity against major biomolecules under physiologically relevant conditions and satisfactory reproducibility (<8%). The method requires minimum technical expertise, is easy to use and is performed without scientific equipment, holding promise as a simple assay of biothiol testing even by non-experts.

The Effect of Oral L-cysteine on Breast Milk and Plasma Cysteine Concentrations.

PurposeGreater oxidative signaling is implicated in major depressive disorder; hence, there is considerable interest in developing oral supplements with anti-oxidant properties to prevent or treat mood disorders, such as postpartum depression. L-cysteine is a precursor for glutathione, an important antioxidant in the brain. So, developing L-cysteine as a dietary supplement may be useful, provided oral supplementation substantially raises its concentration in blood plasma yet does not affect its total concentration in breast milk. This study assessed the effect of oral L-cysteine on its concentration in breast milk and blood plasma of breastfeeding mothers.Participants and MethodsTwenty-four health breastfeeding women were randomly assigned to 0, 1.5, or 3 g of oral L-cysteine. Free and total cysteine in breast milk; and free cysteine in plasma were measured. While breast milk is the gold standard, measurement of infant formulas provides indices of nutritional intake considered safe. Therefore, free cysteine was also measured in six different formulas.ResultsTotal cysteine in breast milk was not affected by oral L-cysteine (Repeated Measures of ANOVA (rANOVA), intervention effect: p=0.75). Free cysteine levels in breast milk did rise (rANOVA, intervention effect: p=0.017), but were within the range of common infant formulas. There was no significant effect of L-cysteine supplementation on free cysteine levels in plasma (rANOVA, intervention effect: p=0.25), although a post hoc analysis found a trend towards greater plasma cysteine 30 minutes after oral supplementation (t(14)=−1.69, p=0.11, 3g versus no-dose).ConclusionThe negligible effect of oral cysteine administration on its total concentration in breast milk was favorable, but the minimal effect on its blood plasma concentration more strongly argues against further development of oral L-cysteine in postpartum, as well as other conditions.

In Situ Imaging of Cysteine in the Brains of Mice with Epilepsy by a Near-Infrared Emissive Fluorescent Probe.

Epilepsy is characterized by oxidative stress in the brain. As the crucial reductive biothiol, cysteine (Cys) directly regulates the occurrence of oxidative stress in the brain. Observations suggest that the decreased cysteine in plasma could potentially serve as a redox biomarker in temporal lobe epilepsy. However, due to the complexity of the brain and lack of appropriate in situ detecting tools, the concentration change and regulation of Cys in epileptic brains remain unclear. Here, we report a near-infrared imaging probe (named Mito-CP) for tracking endogenous Cys in brains of pentylenetetrazole (PTZ)-induced epileptic seizures with high sensitivity and selectivity. Using this probe, we achieved an in situ visualization of the increased Cys in PC12 cells under dithiothreitol stimulation. In addition, Mito-CP was able to real-time monitor Cys fluctuation in lipopolysaccharide-mediated oxidative stress in zebrafish. Ultimately, we directly visualized the precipitous reduction of Cys in epileptic brains for the first time. Mito-CP also revealed the fluctuation of Cys in epileptic brains during the treatment by an antiepileptic drug, curcumin. This work provides an effective tool for Cys imaging in brains and will help to expand the understanding of the pathogenesis of epilepsy.