Zhihan Yan

Systemic perturbations of key metabolites in diabetic rats during the evolution of diabetes studied by urine metabonomics.

Background Elucidation of metabolic profiles during diabetes progression helps understand the pathogenesis of diabetes mellitus. In this study, urine metabonomics was used to identify time-related metabolic changes that occur during the development of diabetes mellitus and characterize the biochemical process of diabetes on a systemic, metabolic level. Methodology/Principal Findings Urine samples were collected from diabetic rats and age-matched controls at different time points: 1, 5, 10, and 15 weeks after diabetes modeling. 1H nuclear magnetic resonance (1H NMR) spectra of the urine samples were obtained and analyzed by multivariate data analysis and quantitative statistical analysis. The metabolic patterns of diabetic groups are separated from the controls at each time point, suggesting that the metabolic profiles of diabetic rats were markedly different from the controls. Moreover, the samples from the diabetic 1-wk group are closely associated, whereas those of the diabetic 15-wk group are scattered, suggesting that the presence of various of complications contributes significantly to the pathogenesis of diabetes. Quantitative analysis indicated that urinary metabolites related to energy metabolism, tricarboxylic acid (TCA) cycle, and methylamine metabolism are involved in the evolution of diabetes. Conclusions/Significance The results highlighted that the numbers of metabolic changes were related to diabetes progression, and the perturbed metabolites represent potential metabolic biomarkers and provide clues that can elucidate the mechanisms underlying the generation and development of diabetes as well as its complication.

Metabolic changes detected by ex vivo high resolution 1H NMR spectroscopy in the striatum of 6-OHDA-induced Parkinson's rat.

Parkinson’s disease (PD) is a neurodegenerative disorder characterized by the progressive loss of the dopaminergic neurons; however, its crucial mechanism of the metabolic changes of neurotransmitters remains ambiguous. The pathological mechanism of PD might involve cerebral metabolism perturbations. In this study, ex vivo proton nuclear magnetic resonance (1H NMR) was used to determine the level changes of 13 metabolites in the bilateral striatum of 6-hydroxydopamine (6-OHDA)-induced PD rats. The results showed that, in the right striatum of 6-OHDA-induced PD rats, increased levels of glutamate (Glu) and γ-aminobutyric acid (GABA) concomitantly with decreased level of glutamine (Gln) were observed compared to the control. Whereas, in the left striatum of 6-OHDA-induced PD rats, increased level of Glu with decreased level of GABA and unchanged Gln were observed. Other cerebral metabolites including lactate, alanine, creatine, succinate, taurine, and glycine were also found to have some perturbations. The observed metabolic changes for Glu, Gln, and GABA are mostly likely the result of a shift in the steady-state equilibrium of the Gln-Glu-GABA metabolic cycle between astrocytes and neurons. The altered Gln and GABA levels are most likely as a strategy to protect neurons from Glu excitotoxic injury after striatal dopamine depletion. Changes in energy metabolism and tricarboxylic acid cycle might be involved in the pathogenesis of PD.

Application of ex vivo 1H NMR metabonomics to the characterization and possible detection of renal cell carcinoma metastases

PurposeRenal cell carcinoma (RCC) is the most prevalent malignancy of the kidney. Its survival rates are very low since most of patients develop metastases beyond the kidney at the time of diagnosis. Early detection is currently by far the most promising approach to reduce RCC mortality. Metabolic alterations have been suggested to have a crucial role in cancer development. Metabonomics can present a holistic picture of the metabolites alterations and provide biomarkers that could revolutionize disease characterization and detection.MethodsEx vivo 1H NMR spectra of tumors and the paired adjacent tissues obtained from living patients with RCC were recorded and analyzed using multivariate statistical techniques combined with quantitative statistical analyses.ResultsIn the present study, we showed that the metabonomes of RCC, either with or without metastases, differ markedly from those of their adjacent tissues. Besides, the RCC patients with metastases can be distinctly differentiated from those without metastases. Metabolic perturbations arising from malignant transformations were also systematically characterized. Compared to the adjacent tissues, RCC tumors had elevated levels of lactate, glutamate, pyruvate, glutamine, and creatine, but decreased levels of acetate, malate, and amino acids including valine, alanine, and aspartate.ConclusionsSystemic changes in metabolite concentrations are most likely the result of cells switching to glycolysis to maintain energy homeostasis. The results suggest that metabonomics may also facilitate the discovery of novel cancer biomarkers and allows the stratification of tumors under different pathophysiological conditions, which might be a valuable future tool for RCC detection and possibly other cancers.

Metabonomic analysis of potential biomarkers and drug targets involved in diabetic nephropathy mice.

Diabetic nephropathy (DN) is one of the lethal manifestations of diabetic systemic microvascular disease. Elucidation of characteristic metabolic alterations during diabetic progression is critical to understand its pathogenesis and identify potential biomarkers and drug targets involved in the disease. In this study, 1H nuclear magnetic resonance (1H NMR)-based metabonomics with correlative analysis was performed to study the characteristic metabolites, as well as the related pathways in urine and kidney samples of db/db diabetic mice, compared with age-matched wildtype mice. The time trajectory plot of db/db mice revealed alterations, in an age-dependent manner, in urinary metabolic profiles along with progression of renal damage and dysfunction. Age-dependent and correlated metabolite analysis identified that cis-aconitate and allantoin could serve as biomarkers for the diagnosis of DN. Further correlative analysis revealed that the enzymes dimethylarginine dimethylaminohydrolase (DDAH), guanosine triphosphate cyclohydrolase I (GTPCH I), and 3-hydroxy-3-methylglutaryl-CoA lyase (HMG-CoA lyase) were involved in dimethylamine metabolism, ketogenesis and GTP metabolism pathways, respectively, and could be potential therapeutic targets for DN. Our results highlight that metabonomic analysis can be used as a tool to identify potential biomarkers and novel therapeutic targets to gain a better understanding of the mechanisms underlying the initiation and progression of diseases.

Neurochemical Changes in the Rat Occipital Cortex and Hippocampus after Repetitive and Profound Hypoglycemia During the Neonatal Period: An Ex Vivo 1H Magnetic Resonance Spectroscopy Study

The brain of a human neonate is more vulnerable to hypoglycemia than that of pediatric and adult patients. Repetitive and profound hypoglycemia during the neonatal period (RPHN) causes brain damage and leads to severe neurologic sequelae. Ex vivo high-resolution 1H nuclear magnetic resonance (NMR) spectroscopy was carried out in the present study to detect metabolite alterations in newborn and adolescent rats and investigate the effects of RPHN on their occipital cortex and hippocampus. Results showed that RPHN induces significant changes in a number of cerebral metabolites, and such changes are region-specific. Among the 16 metabolites detected by ex vivo 1H NMR, RPHN significantly increased the levels of creatine, glutamate, glutamine, γ-aminobutyric acid, and aspartate, as well as other metabolites, including succine, taurine, and myo-inositol, in the occipital cortex of neonatal rats compared with the control. By contrast, changes in these neurochemicals were not significant in the hippocampus of neonatal rats. When the rats had developed into adolescence, the changes above were maintained and the levels of other metabolites, including lactate, N-acetyl aspartate, alanine, choline, glycine, acetate, and ascorbate, increased in the occipital cortex. By contrast, most of these metabolites were reduced in the hippocampus. These metabolic changes suggest that complementary mechanisms exist between these two brain areas. RPHN appears to affect occipital cortex and hippocampal activities, neurotransmitter transition, energy metabolism, and other metabolic equilibria in newborn rats; these effects are further aggravated when the newborn rats develop into adolescence. Changes in the metabolism of neurotransmitter system may be an adaptive measure of the central nervous system in response to RPHN.

Cognitive decline in type 2 diabetic db/db mice may be associated with brain region-specific metabolic disorders

Type 2 diabetes has been associated with cognitive decline, but its metabolic mechanism remains unclear. In the present study, we attempted to investigate brain region-specific metabolic changes in db/db mice with cognitive decline and explore the potential metabolic mechanism linking type 2 diabetes and cognitive decline. We analyzed the metabolic changes in seven brain regions of two types of mice (wild-type mice and db/db mice with cognitive decline) using a 1H NMR-based metabolomic approach. Then, a mixed-model analysis was used to evaluate the effects of mice type, brain region, and their interaction on metabolic changes. Compared with the wild-type mice, the db/db mice with cognitive decline had significant increases in lactate, glutamine (Gln) and taurine as well as significant decreases in alanine, aspartate, choline, succinate, γ-Aminobutyric acid (GABA), glutamate (Glu), glycine, N-acetylaspartate, inosine monophosphate, adenosine monophosphate, adenosine diphosphate, and nicotinamide adenine dinucleotide. Brain region-specific metabolic differences were also observed between these two mouse types. In addition, we found significant interaction effects of mice type and brain region on creatine/phosphocreatine, lactate, aspartate, GABA, N-acetylaspartate and taurine. Based on metabolic pathway analysis, the present study suggests that cognitive decline in db/db mice might be linked to a series of brain region-specific metabolic changes, involving an increase in anaerobic glycolysis, a decrease in tricarboxylic acid (TCA) and Gln-Glu/GABA cycles as well as a disturbance in lactate-alanine shuttle and membrane metabolism.

Serum Metabonomic Analysis of Protective Effects of Curcuma aromatica Oil on Renal Fibrosis Rats

Background Curcuma aromatica oil is a traditional herbal medicine demonstrating protective and anti-fibrosis activities in renal fibrosis patients. However, study of its mechanism of action is challenged by its multiple components and multiple targets that its active agent acts on. Methodology/Principal Findings Nuclear magnetic resonance (NMR)-based metabonomics combined with clinical chemistry and histopathology examination were performed to evaluate intervening effects of Curcuma aromatica oil on renal interstitial fibrosis rats induced by unilateral ureteral obstruction. The metabolite levels were compared based on integral values of serum 1H NMR spectra from rats on 3, 7, 14, and 28 days after the medicine administration. Time trajectory analysis demonstrated that metabolic profiles of the agent-treated rats were restored to control levels after 7 days of dosage. The results confirmed that the agent would be an effective anti-fibrosis medicine in a time-dependent manner, especially in early renal fibrosis stage. Targeted metabolite analysis showed that the medicine could lower levels of lipid, acetoacetate, glucose, phosphorylcholine/choline, trimethylamine oxide and raise levels of pyruvate, glycine in the serum of the rats. Serum clinical chemistry and kidney histopathology examination dovetailed well with the metabonomics data. Conclusions/Significances The results substantiated that Curcuma aromatica oil administration can ameliorate renal fibrosis symptoms by inhibiting some metabolic pathways, including lipids metabolism, glycolysis and methylamine metabolism, which are dominating targets of the agent working in vivo. This study further strengthens the novel analytical approach for evaluating the effect of traditional herbal medicine and elucidating its molecular mechanism.

NMR-based metabolomics reveals brain region-specific metabolic alterations in streptozotocin-induced diabetic rats with cognitive dysfunction

Diabetes mellitus (DM) can result in cognitive dysfunction, but its potential metabolic mechanisms remain unclear. In the present study, we analyzed the metabolite profiling in eight different brain regions of the normal rats and the streptozotocin (STZ)-induced diabetic rats accompanied by cognitive dysfunction using a 1H NMR-based metabolomic approach. A mixed linear model analysis was performed to assess the effects of DM, brain region and their interaction on metabolic changes. We found that different brain regions in rats displayed significant metabolic differences. In addition, the hippocampus was more susceptible to DM compared with other brain regions in rats. More interestingly, significant interaction effects of DM and brain region were observed on alanine, creatine/creatine-phosphate, lactate, succinate, aspartate, glutamate, glutamine, γ-aminobutyric acid, glycine, choline, N-acetylaspartate, myo-inositol and taurine. Based on metabolic pathway analysis, we speculate that cognitive dysfunction in the STZ-induced diabetic rats may be associated with brain region-specific metabolic alterations involving energy metabolism, neurotransmitters, membrane metabolism and osmoregulation.

NMR-Based Metabolomics Reveal a Recovery from Metabolic Changes in the Striatum of 6-OHDA-Induced Rats Treated with Basic Fibroblast Growth Factor.

Basic fibroblast growth factor (bFGF) has a potential role in the treatment of Parkinson’s disease (PD) due to its neurotrophic effect on dopaminergic neurons. To address the metabolic mechanisms of bFGF administration on PD, we have analyzed the metabolic profiles in the striatum of 6-hydroxydopamine (6-OHDA)-induced PD rats after the treatment with bFGF using 1H NMR spectroscopy and partial least squares-discriminant analysis (PLS-DA). In the present study, we found that bFGF treatment can effectively recover PD-induced loss of tyrosine hydroxylase (TH)-positive neurons in the substantia nigra. Metabolomic analyses reveal that PLS-DA failed to discriminate between the control and bFGF groups, indicating that the metabolic difference between these two groups was negligible. However, reliable PLS-DA models can be developed between control and PD groups as well as between PD and bFGF groups, which is attributed to changes in a series of metabolites including GABA, glutamate (Glu), glutamine (Gln), lactate, N-acetylaspartate, creatine, taurine, and myo-inositol. ANOVA results show that the levels of all these metabolites were significantly increased in PD rats relative to normal rats, while PD-induced increase can be significantly reduced to normal levels after bFGF administration. In conclusion, our results suggest that a recovery from PD-induced metabolic disorders may be achieved by bFGF treatment, involving Gln/Glu-GABA cycle, energy metabolism, osmoregulation, and inflammation.

Reliability of a new method for measuring coronal trunk imbalance, the axis-line-angle technique

BACKGROUND CONTEXT Accurate determination of the extent of trunk imbalance in the coronal plane plays a key role in an evaluation of patients with trunk imbalance, such as patients with adolescent idiopathic scoliosis. An established, widely used practice in evaluating trunk imbalance is to drop a plumb line from the C7 vertebra to a key reference axis, the central sacral vertical line (CSVL) in full-spine standing anterioposterior radiographs, and measuring the distance between them, the C7-CSVL. However, measuring the CSVL is subject to intraobserver differences, is error-prone, and is of poor reliability. Therefore, the development of a different way to measure trunk imbalance is needed. PURPOSE This study aimed to describe a new method to measure coronal trunk imbalance, the axis-line-angle technique (ALAT), which measures the angle at the intersection between the C7 plumb line and an axis line drawn from the vertebral centroid of the C7 to the middle of the superior border of the symphysis pubis, and to compare the reliability of the ALAT with that of the C7-CSVL. STUDY DESIGN/SETTING A prospective study at a university hospital was used. PATIENT SAMPLE The patient sample consisted of sixty-nine consecutively enrolled men and women patients, aged 10-18 years, who had trunk imbalance defined as C7-CSVL longer than 20 mm on computed full-spine standing anterioposterior radiographs. OUTCOME MEASURES Data were analyzed to determine the correlation between C7-CSVL and ALAT measurements and to determine intraobserver and interobserver reliabilities. METHODS Using a picture archiving and communication system, three radiologists independently evaluated trunk imbalance on the 69 computed radiographs by measuring the C7-CSVL and by measuring the angle determined by the ALAT. Data were analyzed to determine the correlations between the two measures of trunk imbalance, and to determine intraobserver and interobserver reliabilities of each of them. RESULTS Overall results from the measurements by the C7-CSVL and the ALAT were significantly moderately correlated. Intraobserver assessments by measuring the C7-CSVL and by doing the ALAT failed to find any significant differences between the findings from the first and second assessments by the same radiologist. Interobserver assessments significantly differed between radiologists 1 and 2 for the first assessment measuring the C7-CSVL, and between radiologists 2 and 3 for the second assessment measuring the C7-CSVL. Interobserver assessments by doing the ALAT failed to find any significant differences among the three radiologists for either of the two assessments. CONCLUSIONS Our results indicated that using the ALAT, which is simple and convenient, is of great value in measuring trunk imbalance. For measuring trunk imbalance, the ALAT has essential advantages compared with measuring the C7-CSVL. We encourage spine surgeons to consider using the ALAT in evaluating trunk imbalance.