Jianfei Xia

Plasma esterified and non-esterified fatty acids metabolic profiling using gas chromatography–mass spectrometry and its application in the study of diabetic mellitus and diabetic nephropathy

Using gas chromatography-mass spectrometry (GC-MS), a new metabolic profiling method was established to assess the levels of non-esterified fatty acids (NEFAs) and esterified fatty acids (EFAs) in plasma. The extraction method was simple and robust without removing protein process. With this method 25 fatty acids (FAs), both EFAs and NEFAs, can be recognized simultaneously with only 10 μL plasma. 15 of the 25 can be precisely quantified. The method was validated and then applied into clinical metabonomics research. Five clinical groups including 150 cases were involved. The relationship between FA levels and diabetic mellitus (DM) as well as diabetic nephropathy (DN) pathology was speculated. Furthermore, the possible pathological causes and effects were discussed in detail. Potential biomarkers (p value <0.01) were screened with Students t-test. With the application of partial least squares-discriminant analysis (PLS-DA), different stages were distinguished. The result may be useful for the pathology study of metabolic syndromes, and may also be helpful for monitoring the progression of DM and DN.

Ultraviolet and tandem mass spectrometry for simultaneous quantification of 21 pivotal metabolites in plasma from patients with diabetic nephropathy

A sensitive and specific method was developed for simultaneous determination of 21 compounds related to the diabetic nephropathy (DN) in a single analysis using high-performance liquid chromatography coupled to ultraviolet and tandem mass spectrometry (HPLC-UV/MS/MS) in human plasma. With retention times and MS/MS for peak identification, both UV and MS detectors were used for quantification. Calibration curves suitable for the analysis of plasma were linear (r(2)>0.998) with limits of detection (LOD) from 10 to 1000 ng/mL. Intraday relative standard deviation (R.S.D.) and interday R.S.D. were both lower than 15%. With the case and control study, we found five potential biomarkers of DN, including adenosine, inosine, uric acid, xanthine and creatinine.

Correlations of six related purine metabolites and diabetic nephropathy in Chinese type 2 diabetic patients

OBJECTIVESnThe assessment of the clinical significance of adenosine, adenine, inosine, xanthine, hypoxanthine and uric acid concentrations in patients with type 2 diabetes mellitus (T2DM) and diabetic nephropathy (DN) for the detection of the relationship between purine metabolites and disease.nnnDESIGN AND METHODSnThe study group consisted of 119 subjects which were divided into three groups: control (n=31), type 2 diabetes without nephropathy (DM, n=23) and with nephropathy (DN, n=65). Levels of related metabolites were measured in plasma of all participants.nnnRESULTSnThere is a significant increase of levels of adenosine (P<0.001), inosine (P<0.001), xanthine (P=0.012) and uric acid (P=0.016) with DN compared to DM. The level of xanthine oxidase (reflected by the uric acid: xanthine) did not change.nnnCONCLUSIONnThe levels of adenosine, inosine, uric acid and xanthine may be useful for monitoring the progression of DM and evaluating the treatment.

Phosphomolybdic acid functionalized graphene loading copper nanoparticles modified electrodes for non-enzymatic electrochemical sensing of glucose

A sensitive non-enzymatic glucose electrochemical biosensor (Cu/PMo12-GR/GCE) was developed based on the combination of copper nanoparticles (CuNPs) and phosphomolybdic acid functionalized graphene (PMo12-GR). PMo12-GR films were modified on the surface of glassy carbon electrode (GCE) through electrostatic self-assembly with the aid of poly diallyl dimethyl ammonium chloride (PDDA). Then CuNPs were successfully decorated onto the PMo12-GR modified GCE through electrodeposition. The morphology of Cu/PMo12-GR/GCE was characterized by scanning electron microscope (SEM). Cyclic voltammetry (CV) and chronoamperometry were used to investigate the electrochemical performances of the biosensor. The results indicated that the modified electrode displayed a synergistic effect of PMo12-GR sheets and CuNPs towards the electro-oxidation of glucose in the alkaline solution. At the optimal detection potential of 0.50xa0V, the response towards glucose presented a linear response ranging from 0.10xa0μM to 1.0xa0mM with a detection limit of 3.0xa0×xa010(-2)xa0μMxa0(S/Nxa0=xa03). In addition, Cu/PMo12-GR/GCE possessed a high selectivity, good reproducibility, excellent stability and acceptable recovery, which indicating the potential application in clinical field.

Biomarkers for early diagnosis of type 2 diabetic nephropathy: a study based on an integrated biomarker system

Diabetic nephropathy is a devastating disease that affects a growing number of diabetic patients. A complete cure is very hard to achieve once the disease has been diagnosed, therefore the diagnosis of early stages in diabetic nephropathy has become a hot area. Numbers of molecules have been proposed to be potential biomarkers for this purpose. However, some problems still remain, such as discovering effective biomarkers to diagnose the disease before obvious clinical evidence appears. Thus, the main purpose of this study was to find plasma biomarkers for early diagnosis of type 2 diabetic nephropathy stage 1 and stage 2, as well as separating them from diabetes. 182 subjects (Chinese) were recruited for this study, including 50 healthy controls, 33 type 2 diabetic patients and 99 type 2 diabetic nephropathy patients (33 of these were stage 3). Important clinical indicators including proteinuria, serum creatinine, and urea nitrogen were measured and the glomerular filtration rate was estimated to assess kidney function; fasting blood glucose, postprandial blood glucose and glycated hemoglobin were measured to assess the blood glucose control. Key metabolites and genes in plasma samples were identified and determined using -omic and quantitative techniques. The potential biomarkers were then combined and carefully screened to determine the most informative ones for early diagnosis of type 2 diabetic nephropathy. An integrated biomarker system (IBS) incorporating 6 clinical indicators, 40 metabolites and 5 genes was established. Correlation analysis results revealed that most of the potential biomarkers significantly correlated with the 6 clinical indicators. Discriminant analysis results showed that the developed IBS gave the highest total predictive accuracy (98.9%). Significant test and receiver operating characteristic analysis results indicated that inosine had the highest sensitivity (0.889), specificity (1.000), positive predictive rate (1.000) and negative predictive rate (0.900) amongst the 48 potential biomarkers when separating patients with diabetes from patients with diabetic nephropathy stage 3. Finally, inosine with a cutoff of 0.086 mg L(-1) was combined with estimated GFR to differentiate between diabetic nephropathy stages 1 and 2 from diabetes. The results demonstrate that IBS combined with a proper statistical analysis technique is a powerful tool for biomarker screening.

Correlations of creatine and six related pyrimidine metabolites and diabetic nephropathy in Chinese type 2 diabetic patients

OBJECTIVESnThe assessment of the clinical significance of creatine, cytosine, cytidine, uridine, thymine, thymidine, and 2-deoxyuridine concentrations in patients with type 2 diabetes mellitus (T2DM) and diabetic nephropathy (DN) for the detection of the relationship between pyrimidine metabolites and disease.nnnDESIGN AND METHODSnThe study group consisted of 119 subjects, which were divided to three groups: control (n=31), type 2 diabetes without nephropathy (DM, n=23), and with nephropathy (DN, n=65). Levels of related metabolites were measured in plasma of all participants.nnnRESULTSnThere is a significant increase in levels of cytosine (P<0.001), cytidine (P<0.001), and thymidine (P=0.016) with DN compared to DM. The levels of uridine, thymine, 2-deoxyuridine, and creatine did not change.nnnCONCLUSIONSnThe levels of cytosine, cytidine, and thymidine may be useful for monitoring the progression of DM and evaluating the treatment.

Simultaneous determination of sixteen metabolites related to neural tube defects in maternal serum by liquid chromatography coupling with electrospray tandem mass spectrometry

Disturbances in maternal folate, homocysteine, and glutathione metabolism have been reported to be associated with neural tube defects (NTDs). However, the role played by specific components in the metabolic pathways leading to NTDs remains unclear. Thus an analytical method for simultaneous measurement of sixteen compounds involved in such three metabolic pathways by high performance liquid chromatography-tandem mass spectrometry was developed. The use of hydrophilic chromatography column improved the separation of polar analytes and the detection mode of multiple-reaction monitoring (MRM) enhanced the specificity and sensitivity so as to achieve simultaneous determination of three class of metabolites which have much variance in polarity and contents. The influence of parameters such as temperature, pH, flow rate on the performance of the analytes were studied to get an optimal condition. The method was validated for its linearity, accuracy, and precision, and also used for the analysis of serum samples of NTDs-affected pregnancies and normal women. The result showed that the present method is sensitive and reliable for simultaneous determination of as many as sixteen interesting metabolites which may provide a new means to study the underlying mechanism of NTDs as well as to discover new potential biomarkers.

Correlations of six related pyrimidine metabolites and diabetic retinopathy in Chinese type 2 diabetic patients

BACKGROUNDnDiabetic retinopathy (DR), a kind of diabetic microvascular complication, is the leading cause of visual impairment in adults aged 30 to 65 years. Despite rapid research progress, robust predictors to assess prospectively with high precision the risk for DR in individuals with diabetes are still lacking. We investigated the relationship between pyrimidine metabolites and disease, and find out the potential biomarkers for diagnosis.nnnMETHODSnThe study group consisted of 116 subjects who were divided to 3 groups: control (n=41), type 2 diabetes without retinopathy (DM, n=37), and with retinopathy (DR, n=38). Biochemical and clinical parameters, concentrations of related metabolites, including of cytosine, cytidine, uridine, thymine, thymidine and 2-deoxyuridine were measured in plasma of all participants.nnnRESULTSnThere was a significant increase of concentrations of cytosine (p=0.010), cytidine (p<0.001) and thynidine (p<0.001) with DR compared to DM. The concentration of uridine, thymine and 2-deoxyuridine did not change.nnnCONCLUSIONSnThe concentrations of cytosine, cytidine and thynidine may be useful for monitoring the progression of DR and evaluating the treatment. And cytidine has good sensitivity and specificity for diagnosis.

Recent Trends in Strategies and Methodologies for Metabonomics

Abstract Metabonomics, the scientific research of endogenous metabolic responses of living systems to pathophysiological stimuli or genetic modification, serves as a source of not only qualitative but also quantitative data of metabolites essential for the description of the metabolic cycle. In recent years, metabonomics has been developed into an important and valuable tool in life sciences. Substantial innovations and improvements of analytical technique allow metabonomics to run routinely. Although there are some shortages of metabonomics, new strategies, methodologies, and tools have been proposed to solve the problems by many researchers. Integration, quantification, and normalization are identified as important future trends for the continuous development of metabonomics. The overview, recent developments, and future prospects of metabonomics are shown and discussed in this review.

An electrochemical sensor based on copper-based metal-organic frameworks-graphene composites for determination of dihydroxybenzene isomers in water

A highly and simply sensitive electrochemical sensor was presented for the simultaneous determination of hydroquinone (HQ) and catechol (CT) in the water based on copper centered metal-organic framework-graphene composites (Cu-MOF-GN) [Cu-MOF = Cu3(BTC)2 (BTC = 1, 3, 5-benzenetricarboxylicacid)] modified glassy carbon electrode (Cu-MOF-GN/GCE). The modification procedure was carried out through casting metal-organic framework-graphene oxide composites (Cu-MOF-GO) on the bare glassy carbon electrode and followed by the transformation of Cu-MOF-GO to Cu-MOF-GN by an electrochemical reduction. The electrochemical behavior of HQ and CT at Cu-MOF-GN/GCE was investigated by cyclic voltammetry (CV), differential pulse voltammetry (DPV) and electrochemical impedance spectroscopy (EIS). Under the optimized conditions, the modified electrode had excellent electrocatalytic activity and high selectivity toward HQ and CT. The electrochemical sensor exhibited a linear response in the same range of 1.0 × 10-6 to 1.0 × 10-3M with the detection limits of 5.9 × 10-7M for HQ and 3.3 × 10-7M for CT (S/N = 3). Four samples of tap water spiked with different concentrations of HQ and CT were considered. The method has been applied to the analysis of these isomers in spiked tap water with recoveries from 99.0 ~ 102.9% and relative standard deviations (RSDs) for 5 successive measurements less than 5% were also acceptable. This method was successfully applied to detect target analytes in the real samples with satisfying results. The MOFs-based sensors in the field of electrochemical sensing held a great promise for routine sensing applications.