Effects of DHA-enriched hen egg yolk and L-cysteine supplementation on quality of cryopreserved boar semen

The objective of the present study was to determine the effects of docosahexaenoic acid （DHA）-enriched hen egg yolks and L-cysteine supplementation on the qualities of the cryopreserved boar semen. A total of 15 ejaculates from 5 Pietrain boars were divided into 4 groups according to the compositions of the freezing extenders used, that is, normal hen egg yolk （group Ⅰ）, DHA-enriched hen egg yolk （group Ⅱ）, normal hen egg yolk with 5 mmol L^-1 of cysteine supplementation （group Ⅲ） and DHA-enriched hen egg yolk with 5 mmol L1 of cysteine supplementation （group Ⅳ）. The semen was cryopreserved using controlled rate freezer and was thawed at 50℃ for 12 s. Progressive motility, sperm viability, acrosome integrity and functional integrity of sperm plasma membrane of the post-thawed semen were evaluated. The supplementation of L-cysteine in the freezing extender alone （group Ⅲ） improved progressive motility （P 〈 0.05）, and the supplementation of L-cysteine in combination with DHA-enriched hen egg yolk （group Ⅳ） improved both progressive motility （P 〈 0.05） and acrosome integrity （P 〈 0.01）. The use of DHA-enriched hen egg yolk alone （group Ⅱ） did not enhance any of the post-thawed semen qualities （P 〉 0.05）. In conclusion, the supplementation of antioxidant L-cysteine alone or in combination with DHA-enriched hen egg yolk significantly improved the post-thawed semen qualities, especially progressive motility and acrosome integrity.

Supplemental effect of varying L-cysteine concentrations on the quality of cryopreserved boar semen

Cryopreservation is associated with the production of reactive oxygen species, which leads to lipid peroxidation of the sperm membrane and consequently a reduction in sperm motility and decreased fertility potential. The aim of this study was to determine the optimal concentration of L-cysteine needed for cryopreservation of boar semen. Twelve boars provided semen of proven motility and morphology for this study. The semen was divided into four portions in which the lactose-egg yolk （LEY） extender used to resuspend the centrifuged sperm pellet was supplemented with various concentrations of L-cysteine to reach 0 mmol L^-1 （group Ⅰ, control）, 5 mmol L^-1 （group Ⅱ）, 10 mmol L^-1 （group Ⅲ） and 15 mmol L^-1 （group Ⅳ）. Semen suspensions were loaded in straws （0.5 mL） and placed in a controlled-rate freezer. After cryopreservation, frozen semen samples were thawed and investigated for progressive motility, viability using SYBR-14/EthD-1 staining and acrosome integrity using FITC-PNA/EthD-1 staining. There was a significantly higher （P 〈 0.01） percentage of progressive motility, viability and acrosomal integrity in two L-cysteine-supplemented groups （group Ⅱ and group Ⅲ） compared with the control. There was a biphasic effect of L-cysteine, with the highest percentage of progressive motility, viability and acrosomal integrity in group Ⅲ. In conclusion, 5 or 10 mmol L^-1 was the optimum concentration of L-cysteine to be added to the LEY extender for improving the quality of frozen-thawed boar semen.

Influence of L-Cysteine Concentration on Oxidation-reduction Potential and Biohydrogen Production

The effects of L-cysteine concentration on biohydrogen production by Enterobacterium Bacterium M580 were investigated in batch cultivation.The experimental results showed that L-cysteine could enhance the cell growth,hydrogen production rate and hydrogen yield when its concentration was less than 500 mg·L-1,while it had negative effects when its concentration was higher than 500 mg·L-1.The hydrogen production was the highest 1.29 mol·mol-1(H2/glucose) when 300 mg·L-1L-cysteine was added into the culture,and the yield was 9.4% higher than that in the control.The oxidation-reduction potential(ORP) ,which was influenced by L-cysteine,also affected hydrogen production.The ORP values were in the range-300 mV to-150 mV when the L-cysteine concentration was higher than 500 mg·L-1.Although the ORP in this range was favorable for hydrogen production,it was not suitable for the biomass growth.Hence,less hydrogen was produced.When the L-cysteine concentration was lower than 500 mg·L-1,the ORP was more suitable for both biomass growth and hydrogen production.In addition,at least 91%glucose was consumed when L-cysteine was added to the culture media,compared to the 97.37% consumption without L-cysteine added.

Electrochemical investigation on the film of L-cysteine self-assembled to nanoparticles on a gold electrode

The film contained L-cysteine and gold nanoparticles were provided by self-assembled monolayers (SAMs) and potentiostatic electrodeposition technology on the gold electrode. Two methods were used to study the film: In the first, cyclic voltammetry (CV) was used to inspect the functional groups of the film and the same time hydroquinone was chosen to be a probe molecule in the based solution;secondly, based on analytical technology of scanning electrochemical microscopy (SECM), the heterogeneous rate constant (keff) between solid phase (the modified electrode) and liquid phase (K3Fe(CN)6) was obtained. As a result, the better binary catalysis of hydroquinone was demonstrated and the heterogeneous rate constant (keff) is the greater at 8 h for L-cysteine self-assembled monolayers (SAMs).

Effect of L-cysteine on bioleaching of Ni-Cu sulphide by A. manzaensis

The effect of L-cysteine in different concentrations on the bioleaching of Ni-Cu sulfide was studied with an extremely thermophilic archaea,Acidianus manzaensis. It is found that adding certain amounts of L-cysteine to the bioleaching system of Ni-Cu sulfide largely enhances the leaching rate. X-ray diffraction (XRD) patterns show the change of bioleached solid residues and the effect of L-cysteine on the surface charges of minerals. Zeta potential and IR spectra of mineral surface show that the interaction between L-cysteine and mineral leads to the formation of metal complex,which is propitious to the bioleaching of Ni-Cu sulfide by Acidianus manzaensis.

Electrocatalytic oxidation behavior of L-cysteine at Pt microparticles modified nanofibrous polyaniline film electrode

Platinum(Pt)/nanofibrous polyaniline(PANI) electrode was prepared by pulse galvanostatic method and characterized by scanning electron microscopy.The electrochemical behavior of L-cysteine at the Pt/nanofibrous PANI electrode was investigated by cyclic voltammetry.The results indicate that the pH value of the solution and the Pt loading of the electrode have great effect on the electrocatalytic property of the Pt /nanofibrous PANI electrode;the suitable Pt loading of the electrode is 600 μg/cm2 and the suitable pH value of the solution is 4.5 for investigating L-cysteine oxidation.The L-cysteine sensor based on the Pt/nanofibrous PANI electrode has a good selectivity,reproducibility and stability.The Pt/nanofibrous PANI electrode is highly sensitive to L-cysteine,and the linear calibration curve for the oxidation of L-cysteine can be observed in the range of 0.2-5.0 mmol/L.

L-Cysteine-assisted Synthesis of Copper Gallium Sulfide Microspheres

An effective L-cysteine-assisted synthetic route has been successfully developed to prepare copper gallium sulfide（CuGaS2） microspheres under solvothermal conditions with CuCI2.2HzO, GaC13 and L-cysteine as source materials, in which L-cysteine was used as the sulfide source and complexing molecule. The experiments revealed that the synthesized sample was of a typical CuGaS2 tetragonal structure. Moreover, the prepared CuGaS2 crystals consisting of microspheres made up of nanoflakes, and the diameter of the nanoflakes was about 20 nm. Raman spectrum of the obtained CuGaS2 exhibits a high-intensity peak of the A1 mode at 306 cm^-1. Meanwhile, a possible growth mechanism was proposed based on the investigations.

Reparative histogenesis of skin: Reaction on the application of l-cysteine of argentum nitrate gel

The effect of L-cysteine of argentum nitrate gel on the wound process of experimental animals is investigated. The results show that the nanogel, being bacteriostatic, accelerates the course of inflammation phase resulting in fast cleansing of the wound surface and stimulation of the granulation tissue formation. The main cell elements of this tissue—fibroplasts are characterized by the state of functional excitation. The time of wound healing with the use of L-cysteine of argentum nitrate gel was reduced by three days, and the index of wound repair acceleration was about 20%.

Application of urinary N-acetyl-β-D-glucosaminidase combined with serum retinol-binding protein in early detection of diabetic nephropathy

BACKGROUND Diabetic nephropathy(DN)is a microangiopathy of type 2 diabetes mellitus(T2DM),which can damage the kidney through various ways and mechanisms due to the nature of the disease,involving the renal interstitium and glomeruli.However,in the early stage of the disease,patients only showed kidney volume increase and glomerular hyperthyroidism,and typical symptoms that are difficult to arouse individual attention were noticed.AIM To observe the expression of serum retinol-binding protein(RBP)and urinary Nacetyl-β-D-glucosaminidase(NAG)in patients with DN,and to analyze their value in disease prediction,so as to provide new targets for early diagnosis and treatment of DN.METHODS The baseline data of 50 T2DM patients treated in our hospital between January 2021 and December 2022 were retrospectively reviewed and included in group A.The baseline data of 50 patients with type 2 DN admitted to our hospital during the same period were collected and included in group B.The baseline data and serum RBP and urine NAG expression were compared between the two groups to analyze their value in the early prediction of DN.RESULTS There was no significant difference in age,gender,duration of diabetes,combined hyperlipidemia and combined hypertension between the two groups(P>0.05);the expression of urinary NAG and serum RBP in group B was higher than that in group A,and the difference was statistically significant(P<0.05);a multiple logistic regression model was established,and the results showed that urinary NAG and serum RBP were related to the presence or absence of injury in diabetic patients,and overexpression of urinary NAG and serum RBP may be risk factors for renal injury in T2DM patients(OR>1,P<0.05);receiver operating curve curve was plotted,and the results showed that the area under the curve of urinary NAG and serum RBP expression alone and in combination for predicting DN was>0.80,and the predictive value was satisfactory;bivariate Spearman linear correlation analysis showed that there was a positive correlation between urinary NAG and serum RBP expression in patients with DN(r=0.566,P=0.000).CONCLUSION The increased expression of urinary NAG and serum RBP may be the risk factors leading to the progression of T2DM to DN.The possibility of DN can be considered in patients with urinary NAG and serum RBP overexpression by examining the expression of urinary NAG and serum RBP in patients with T2DM in clinical practice.

Denaturation Kinetics of N-Acetyl-β-D-glucosaminidase from Scylla serrata in Urea Solution

N-Acetyl-β-D-glucosaminidase（NAGase, EC 3.2.1.52）, which catalyzes the cleavage of N-acetylgluco- samine polymers, plays important roles in the molting, digestion of chitinous foods in green crab. In the study, the efforts of urea on the activity of NAGase purified from the viscera of green crab（Scylla serrata） have been studied. The results show that appropriate concentrations of urea can lead to reversible inactivation of the enzyme, and the value of the inhibitor concentration leading to 50% of enzyme activity lost（IC50） is estimated to be 0.63 mol/L. The inactivation kinetics has been studied via the kinetic method of the substrate reaction. The rate constants of inactivation have been determined. The value of k＋0 is larger than that of k′＋0, indicating the free enzyme molecule is more fragile than the enzyme-substrate complex in urea solution. It is suggested that the presence of the substrate offers the marked protection of this enzyme against inactivation by urea.

The miR-9-5p/CXCL11 pathway is a key target of hydrogen sulfide-mediated inhibition of neuroinflammation in hypoxic ischemic brain injury

We previously showed that hydrogen sulfide(H2S)has a neuroprotective effect in the context of hypoxic ischemic brain injury in neonatal mice.However,the precise mechanism underlying the role of H2S in this situation remains unclear.In this study,we used a neonatal mouse model of hypoxic ischemic brain injury and a lipopolysaccharide-stimulated BV2 cell model and found that treatment with L-cysteine,a H2S precursor,attenuated the cerebral infarction and cerebral atrophy induced by hypoxia and ischemia and increased the expression of miR-9-5p and cystathionineβsynthase(a major H2S synthetase in the brain)in the prefrontal cortex.We also found that an miR-9-5p inhibitor blocked the expression of cystathionineβsynthase in the prefrontal cortex in mice with brain injury caused by hypoxia and ischemia.Furthermore,miR-9-5p overexpression increased cystathionine-β-synthase and H2S expression in the injured prefrontal cortex of mice with hypoxic ischemic brain injury.L-cysteine decreased the expression of CXCL11,an miR-9-5p target gene,in the prefrontal cortex of the mouse model and in lipopolysaccharide-stimulated BV-2 cells and increased the levels of proinflammatory cytokines BNIP3,FSTL1,SOCS2 and SOCS5,while treatment with an miR-9-5p inhibitor reversed these changes.These findings suggest that H2S can reduce neuroinflammation in a neonatal mouse model of hypoxic ischemic brain injury through regulating the miR-9-5p/CXCL11 axis and restoringβ-synthase expression,thereby playing a role in reducing neuroinflammation in hypoxic ischemic brain injury.

Historical tillage promotes grass-legume mixtures establishment and accelerates soil microbial activity and organic carbon decomposition

Perennial grass-legume mixtures have been extensively used to restore degraded grasslands,increasing grassland productivity and forage quality.Tillage is crucial for seedbed preparation and sustainable weed management for the establishment of grass-legume mixtures.However,a common concern is that intensive tillage may alter soil characteristics,leading to losses in soil organic carbon(SOC).We investigated the plant community composition,SOC,soil microbial biomass carbon(MBC),soil enzyme activities,and soil properties in long-term perennial grass-legume mixtures under two different tillage intensities(once and twice)as well as in a fenced grassland(FG).The establishment of grass-legume mixtures increased plant species diversity and plant community coverage,compared with FG.Compared with once tilled grassland(OTG),twice tilled grassland(TTG)enhanced the coverage of high-quality leguminous forage species by 380.3%.Grass-legume mixtures with historical tillage decreased SOC and dissolved organic carbon(DOC)concentrations,whereas soil MBC concentrations in OTG and TTG increased by 16.0%and 16.4%,respectively,compared with FG.TTG significantly decreased the activity of N-acetyl-β-D-glucosaminidase(NAG)by 72.3%,whereas soil enzymeβ-glucosidase(βG)in OTG and TTG increased by 55.9%and 27.3%,respectively,compared with FG.Correlation analysis indicated a close association of the increase in MBC andβG activities with the rapid decline in SOC.This result suggested that MBC was a key driving factor in soil carbon storage dynamics,potentially accelerating soil carbon cycling and facilitating biogeochemical cycling.The establishment of grass-legume mixtures effectively improves forage quality and boosts plant diversity,thereby facilitating the restoration of degraded grasslands.Although tillage assists in establishing legume-grass mixtures by controlling weeds,it accelerates microbial activity and organic carbon decomposition.Our findings provide a foundation for understanding the process and effectiveness of restoration management in degraded grasslands.

L-Cysteine inhibits root elongation through auxin/PLETHORA and SCR/SHR pathway in Arabidopsis thaliana

L-Cysteine plays a prominent role in sulfur metabo- lism of plants. However, its role in root development is largely unknown. Here, we report that L-cysteine reduces primary root growth in a dosage-dependent manner. Elevating cellular L-cysteine level by exposing Arabidopsis thaliana seedlings to high L-cysteine, buthionine sulphoximine, or O-acetylserine leads to altered auxin maximum in root tips, the expression of quiescent center cell marker as well as the decrease of the auxin carriers PIN1, PIN2, PIN3, and PIN7 of primary roots. We also show that high L-cysteine significantly reduces the protein level of two sets of stem cell specific transcription factors PLETHORA1/2 and SCR/SHR. However, L-cysteine does not downregulate the transcript level of PiNs, PLTs, or SCR/SHR, suggesting that an uncharacterized post-transcriptional mechanism may regulate the accumulation of PIN, PLT, and SCR/SHR proteins and auxin transport in the root tips. These results suggest that endogenous L-cysteine level acts to maintain root stem cell niche by regulating basal- and auxin-induced expression of PLT1/2 and 5CR/SHR. L-Cysteine may serve as a link between sulfate assimilation and auxin in regulating root growth.

Electrocatalytic determination of L-cysteine using a modified carbon nanotube paste electrode:Application to the analysis of some real samples

The electrooxidation of L-cysteine（L-Cys） was studied using a benzoylferrocene（BF） modified multi-wall carbon nanotube paste electrode（BFCNPE） using cyclic voltammetry（CV）,square wave voltammetry（SWV） and chronoamperometry（CHA）.Under optimum pH in CV the oxidation of L-Cys occurs at a potential about 215 mV less positive than that at the surface of unmodified carbon paste electrode.The catalytic oxidation peak currents were dependent on the L-Cys concentration and a linear calibration curve was obtained in the range 0.7-350.0 mmol/L of L-Cys with SWV method.The detection limit（3s） was determined as 0.1 mmol/L.This method was also used for the determination of L-Cys in some real samples.

Size-controlled green synthesis of silver nanoparticles assisted by L-cysteine

A green and size-controlled synthesis of silver nanoparticles （Ag NPs） in aqueous solution with the assistance of L-cysteine is presented. The size of Ag NPs decreases with the increase of L-cysteine concentration, and thus can be controlled by adjusting L-cysteine concentration. TEM analysis shows that Ag NPs with an average size of 3 nm can be produced in the presence of 1.0 mmol/L L-cysteine, about one sixth of the size of Ag NPs obtained in the absence of L-cysteine （17 nm）. The assynthesized silver colloidal solution is stable and can be stored at room temperature for at least two months without any precipitation. This L-cysteine assisted method is simple, feasible and efficient, and would facilitate the production and application of Ag NPs.

Electrochemical Oxidation of L-Cystenine in SDS/BA/H_2O Microemulsion

The electrochemical oxidation of L-cysteine in an SDS/BA/H_2O microemulsion system was studied with the methods of ultramicroelectrode cyclic voltammetry and AC impedance. The catalytic efficiency of the microemulsion on the electrochemical oxidation increases with the increase of BA or SDS content, but decreases with the increase of the water content because of the effects of BA, SDS and water on the solubilization of L-cysteine in the microemulsion. Furthermore, the catalytic efficiency of the bicontinuous structure is greater than that of an O/W microemulsion system. The results derived from both the rate constant k0 and Gibbs free energy ΔG≠ accord with those from the catalytic efficiency.

Design ofL-Cysteine Functionalized Au@SiO2@Fe3O4/Nitrogen-doped Graphene Nanocomposite and Its Application in Electrochemical Detection of Pb2＋

A novel magnetic electrochemical sensor was designed for determination of lead ions based on gold na- noparticles（AuNPs）@SiO2@Fe3O4/nitrogen-doped graphene（NG） composites functionalized with L-cysteine. The Au@SiO2@Fe3O4/NG was synthesized by the electrostatic adsorption between AuNPs and SiO2-coated Fe304 NPs（SiO2@Fe304） and the amide bond between Au@SiO2@Fe3O4 and NG. L-Cysteine was successfully functionalized on the surface of Au@SiO2@Fe3O4/NG nanocomposites via the S--Au bond between L-cysteine and AuNPs. Owing to numerous active sites in L-cysteines and high conductivity of Au@SiO2@Fe3O4/NG composites, the pro- posed electrochemical sensor exhibited a well-distributed nanostructure and high responsivity toward Pb（II）. The sensor linearly responded to Pb2＋ concentration in the range of 5-80 μg/L with a detection limit of 0.6 μg/L, indicating that this L-cysteine functionalized Au@SiO2@Fe3O4/NG composite could be a promising candidate material for the detection of Pb2＋.

Microwave-assisted synthesis of L-cysteine-capped nickel nanoparticles for catalytic reduction of 4-nitrophenol

A simple and efficient microwave-assisted procedure for synthesis of L-cysteine-capped nickel nanoparticles(cyst-Ni NPs) in ethylene glycol solvent was demonstrated. The as-synthesised NPs were characterised by ultraviolet–visible(UV–Vis) spectrophotometer, Fourier transform infrared(FTIR) spectroscopy, transmission electron microscopy(TEM) and X-ray diffractometry(XRD). The cyst-Ni NPs are proved to be excellent heterogeneous catalysts for the 100% reduction of 4-nitrophenol(4-NPh) in the presence of reductant(Na BH4)within reaction time of 40 s. In contrast, Raney nickel in similar sample environments shows only 25.5% reduction.The kinetic and energetic behaviours of cyst-Ni NPs were also studied, and the reduction reaction is determined to follow pseudo-first-order kinetics with a rate constant value of 0.115 s-1 and activation energy of 36.1 kJ·mol-1. In addition to its high catalytic competence, cyst-Ni NPs catalyst exhibits excellent recyclability with negligible catalytic poisoning.

Enhanced degradation of organic contaminants by Fe(Ⅲ)/peroxymonosulfate process with L-cysteine

The difficulty in Fe(Ⅲ)/Fe(Ⅱ) conversion in the Fe(Ⅲ)/peroxymonosulfate(PMS) process limits its efficiency and application.Herein,L-cysteine(Cys),a green natural organic ligand with reducing capability,was innovatively introduced into Fe(Ⅲ)/PMS to construct an excellent Cys/Fe(Ⅲ)/PMS process.The Cys/Fe(Ⅲ)/PMS process,at room temperature,can degrade a variety of organic contaminants,including dyes,phenolic compounds,and pharmaceuticals.In subsequent experiments with acid orange 7(A07),the AO7 degradation efficiency followed pseudo-first-order kinetic which exhibited an initial "fast stage" and a second "slow stage".The rate constant values ranged depending on the initial Cys,Fe(Ⅲ),PMS,and AO7 concentrations,reaction temperature,and pH values.In addition,the presence of Cl^(-),NO_(3)^(-),and SO_(4)^(2-) had negligible impact while HCO_(3)^(-) and humic acid inhibited the degradation of AO7.Furthermore,radical scavenger experiments and methyl phenyl sulfoxide(PMSO) transformation assay indicated that sulfate radical,hydroxyl radical,and ferryl ion(Fe(Ⅳ)) were the dominant reactive species involved in the Cys/Fe(Ⅲ)/PMS process.Finally,based on the results of gas chromatography-mass spectrometry,several AO7 degradation pathways,including N=N cleavage,hydroxylation,and ring opening were proposed.This study provided a new insight to improve the efficiency of Fe(Ⅲ)/PMS process by accelerating Fe(Ⅲ)/Fe(Ⅱ)cycle with Cys.

Early renal injury indicators can help evaluate renal injury in patients with chronic hepatitis B with long-term nucleos(t)ide therapy

BACKGROUND Patients with chronic hepatitis B(CHB)with long-term nucleos(t)ide therapy may experience renal insufficiency.Traditional renal function indicators,such as urine protein,serum urea nitrogen(BUN),and serum creatinine,are normal when early mild lesions occur.Therefore,more sensitive renal function indicators are needed.AIM To investigate the significance of early renal injury indicators in evaluating renal injury in patients with CHB with long-term nucleos(t)ide therapy.METHODS We collected the clinical data of 69 outpatients with CHB at Peking University First Hospital from March 2018 to January 2020 who had been treated with longterm nucleos(t)ide therapy and analyzed the results of early renal injury indicators.Continuous normal distribution data were analyzed by the t-test to determine the difference between two groups.Continuous non-normally distributed data were analyzed by the Mann-Whitney U-test between two groups.The Kruskal-Wallis H test was used to determine the differences among multiple groups.Enumeration data were analyzed by the chi-square test.The related factors of early renal injury indicators were analyzed by logistic regression analysis.RESULTS The average treatment duration with nucleos(t)ide analogs of the 69 patients with CHB was 99.7±28.7 mo.The cases of patients with elevated BUN and hypophosphatemia were 6(8.7%)and 13(18.8%),respectively;31(44.9%)patients had abnormal early renal injury indicators,including 9 patients with abnormal urine microalbumin,7 patients with abnormal urine immunoglobulin,6 patients with abnormal urine transferrin,and 19 patients with abnormalα1 microglobulin.There were no significant differences in the mean values of age,sex,BUN,estimated glomerular filtration rate(eGFR),serum uric acid,serum calcium,or serum phosphorus between the two groups of patients with and without early renal injury indicators.However,the mean levels of serum creatinine and urine creatinine,N-acetyl-β-D-glucosidase enzyme,α1 microglobulin,and urine immunoglobulin in the former group of patients were significantly higher than those in the latter group of patients(P<0.05).The incidence of early renal injury in patients with eGFR≥90,60-89,and 30-59 mL/(min·1.73 m2)was 36.4%(8/22),47.6%(20/42),and 60%(3/5),respectively.Logistic regression analysis results showed that gamma-glutamyl transpeptidase[odds ratio(OR)=1.05(1.008-1.093),P=0.020],direct bilirubin[OR=1.548(1.111-2.159),P=0.010],serum creatinine[OR=1.079(1.022-1.139),P=0.006],and age[OR=0.981(0.942-1.022),P=0.357]were independent predictors of early renal injury.CONCLUSION Patients with CHB treated with long-term nucleos(t)ide analog therapy had a high probability of early renal injury,and early renal injury indicators were highly sensitive and could be used to monitor early renal impairment.