Biomarkers of rapid chronic kidney disease progression in type 2 diabetes.

Here we evaluated the performance of a large set of serum biomarkers for the prediction of rapid progression of chronic kidney disease (CKD) in patients with type 2 diabetes. We used a case-control design nested within a prospective cohort of patients with baseline eGFR 30-60 ml/min per 1.73 m(2). Within a 3.5-year period of Go-DARTS study patients, 154 had over a 40% eGFR decline and 153 controls maintained over 95% of baseline eGFR. A total of 207 serum biomarkers were measured and logistic regression was used with forward selection to choose a subset that were maximized on top of clinical variables including age, gender, hemoglobin A1c, eGFR, and albuminuria. Nested cross-validation determined the best number of biomarkers to retain and evaluate for predictive performance. Ultimately, 30 biomarkers showed significant associations with rapid progression and adjusted for clinical characteristics. A panel of 14 biomarkers increased the area under the ROC curve from 0.706 (clinical data alone) to 0.868. Biomarkers selected included fibroblast growth factor-21, the symmetric to asymmetric dimethylarginine ratio, ß2-microglobulin, C16-acylcarnitine, and kidney injury molecule-1. Use of more extensive clinical data including prebaseline eGFR slope improved prediction but to a lesser extent than biomarkers (area under the ROC curve of 0.793). Thus we identified several novel associations of biomarkers with CKD progression and the utility of a small panel of biomarkers to improve prediction.

Serum uric acid and cardiovascular risk among Portuguese adolescents.

PURPOSE: The aim of the study was to investigate the association between serum uric acid (SUA) and cardiovascular risk classes (CRCs) in adolescents using a cluster-based approach. METHODS: A cross-sectional evaluation was carried out in the 2007-2008 school year, including adolescents born in 1990 and enrolled in the schools of Porto, Portugal. The analysis included 1,286 adolescents. To identify CRC, a normal mixture model was performed including several biological cardiovascular risk factors. A multinomial logistic regression model was applied to explore the association between SUA and each CRC. RESULTS: Three classes were extracted using model-based cluster analysis (low, medium, and high CRC). The high CRC accounted for the smallest proportion of participants (5.6%) and represented the adolescents with higher waist circumference, systolic and diastolic blood pressures, total cholesterol, triglycerides, and insulin levels. Adolescents at increased risk of cardiovascular disease had significantly higher mean concentrations of SUA compared with adolescents at low cardiovascular risk (55.0 vs. 51.5 mg/L in males and 41.9 vs. 37.6 mg/L in females). After adjustment and considering low CRC as reference, SUA was positively associated with high CRC in both sexes (odds ratio, 1.04; 95% confidence interval, 1.00-1.07 in males; and odds ratio, 1.04; 95% confidence interval, 1.01-1.07 in females). CONCLUSIONS: Among 17-year-old adolescents, SUA increases were positively associated with higher CRC.

The development and validation of a fast and robust dried blood spot based lipid profiling method to study infant metabolism.

Early life exposures and metabolic programming are associated with later disease risk. In particular lipid metabolism is thought to play a key role in the development of the metabolic syndrome and insulin resistance in later life. Investigative studies of metabolic programming are limited by the ethics and practicalities of sample collection in small infants. Dried blood spots on filter paper, derived from heel pricks are considered as the most suitable option for this age group. We validated a novel lipid profiling method, based on high resolution mass spectrometry to successfully determine the lipid composition of infants using dried blood spots. The spotting and air drying of blood on paper has noticeable effects on many of the lipids, leading to lipid oxidation and hydrolysis, which demand careful interpretation of the obtained data. We compared the lipid profiles from plasma or whole blood samples and the results from dried blood spots to determine if these revealed the same inter-subject differences. The results from dried blood spots were no less reproducible than other lipid profiling methods which required comparatively larger sample volumes. Therefore, lipid profiles obtained from dried blood spots can be successfully used to monitor infancy lipid metabolism and we show significant differences in the lipid metabolism of infants at age 3 versus 12 months.

Homocysteine level in schizophrenia patients.

OBJECTIVE: Elevated serum levels of homocysteine have been shown to be associated with schizophrenia in some studies, but the evidence is still limited and mixed. The aim of the present study was therefore to evaluate the serum homocysteine level in Chinese in schizophrenia patients and assess its association with clinical phenotypes of the disease. METHOD: A total of 250 inpatients and 250 healthy controls were identified at Kowloon Hospital and the Red Cross Blood Donation Centre, respectively. Each subject was evaluated with a structured diagnostic interview. Demographic data were collected and blood was analysed for homocysteine level. The Positive and Negative Syndrome Scale was used to grade clinical symptoms of schizophrenia. Confounding factors affecting homocysteine levels were controlled by strict exclusion criteria or statistical methods. RESULTS: Serum homocysteine level was elevated in Chinese schizophrenia patients. Both male (mean, 12.26 micromol L(-1); control, 11.40 micromol L(-1), p = 0.026) and female (mean, 9.61 micromol L(-1); control, 8.33 micromol L(-1), p < 0.001) patients had a higher serum homocysteine level than the healthy controls, and these differences persisted after controlling for age. There was no significant association between serum homocysteine level and duration of illness, clinical symptoms or age of onset of schizophrenia. CONCLUSION: The serum homocysteine levels were elevated in both male and female Chinese schizophrenia patients. The levels were not apparently related to other clinical parameters.

An approach towards method development for untargeted urinary metabolite profiling in metabonomic research using UPLC/QToF MS.

The application of LC-MS for untargeted urinary metabolite profiling in metabonomic research has gained much interest in recent years. However, the effects of varying sample pre-treatments and LC conditions on generic metabolite profiling have not been studied. We aimed to evaluate the effects of varying experimental conditions on data acquisition in untargeted urinary metabolite profiling using UPLC/QToF MS. In-house QC sample clustering was used to monitor the performance of the analytical platform. In terms of sample pre-treatment, results showed that untreated filtered urine yielded the highest number of features but dilution with methanol provided a more homogenous urinary metabolic profile with less variation in number of features and feature intensities. An increased cycle time with a lower flow rate (400 microl/min vs 600 microl/min) also resulted in a higher number of features with less variability. The step elution gradient yielded the highest number of features and the best chromatographic resolution among three different elution gradients tested. The maximum retention time and mass shift were only 0.03 min and 0.0015 Da respectively over 600 injections. The analytical platform also showed excellent robustness as evident by tight QC sample clustering. To conclude, we have investigated LC conditions by studying variability and repeatability of LC-MS data for untargeted urinary metabolite profiling.

The cytoprotective effect of alpha-tocopherol and daidzein against d-galactosamine-induced oxidative damage in the rat liver.

We hypothesized that the hepatotoxicity that develops after the induction of oxidative stress (induced by d-galactosamine [GalN]) can be ameliorated by alpha-tocopherol (ATC) and the soy isoflavone daidzein. To test this, we ranked and assigned male Wistar rats into 6 groups, which involved pretreatment (ATC or daidzein) for 1 hour followed by treatment (GalN) for 23 hours. Histopathologic analysis showed that GalN administration induced marked necrosis (P < .001), steatosis (P < .001), both lobular and portal inflammations (P < .001), overall histopathologic score (P < .001), and activation of caspase-3 in the liver (P < .001). Immunohistochemical staining of malondialdehyde-protein adducts, a measure of oxidative stress, was increased in response to GalN (P < .001). Paradoxically, there were increases in total (P < .05) and cytosolic superoxide dismutase (P < .001) activities after GalN administration, indicative of an up-regulation of antioxidant defenses. The concentration of total protein (P < .001), albumin (P < .01), and globulin fractions (P < .001) in the plasma, as well as the activity of aspartate aminotransferase (P < .001), was significantly perturbed after GalN treatment, reflective of overall acute hepatic injury. Administration of daidzein showed a significant amelioration of the Ga1N-induced increase in malondialdehyde-protein adducts (P < .01) and cytosolic superoxide dismutase activities (P < .01) in the liver. However, all other variables were not significantly altered in response to daidzein. In response to ATC pretreatment, the total histopathologic score (P < .05), degree of necrosis (P < .05), and both lobular (P < .05) and portal (P = .05) inflammations were significantly ameliorated. To conclude, both daidzein and ATC protect the liver against oxidative damage possibly via different pathways.

Protective effect of daidzein against acute ethanol-induced lipid peroxidation in rat jejunum.

Ethanol causes extensive damage to the intestinal tract from the oropharynx to the rectum. The jejunum has also been shown to be particularly vulnerable to the deleterious effects of ethanol. We hypothesized that (I) the pathogenesis of acute alcohol-mediated injury in the small intestine involves generation of reactive oxygen species, and consequentially, enhanced lipid peroxidation; (II) the pathogenic changes due to alcohol can be ameliorated with daidzein pretreatment. To test these hypotheses male Wistar rats (n=24) were divided into four groups as follows (pretreatment followed by treatment): [A] carrier+saline (control); [B] daidzein+saline; [C] carrier+ethanol; [D] daidzein+ethanol. Daidzein (100 mg/kg) or carrier (Intralipid) pretreatment was twice administered as a single dose, whereas ethanol (75 mmol/kg) or saline (0.15 mol/l NaCl) treatment was administered once only. At 24 h after ethanol or saline was administered, rats were sacrificed. The analytes 7alpha-and 7beta-hydroperoxycholest-5-en-3beta-ol (7alpha-OOH and 7beta-OOH), 7alpha-and 7beta-hydroxycholesterol (7alpha-OH and 7beta-OH), and 7-ketocholesterol (7-keto) in jejunum were analyzed by HPLC. The data showed that daidzein per se did not affect levels of cholesterol hydroperoxides nor oxysterols. However, there were significant increases in 7alpha- and 7beta-OOHs, 7alpha- and 7beta-OHs, and 7-keto after ethanol dosage compared to controls. Daidzein ameliorated these effects, i.e., values in the daidzein+ethanol group were similar to those in the carrier+saline (control) group. This is the first report showing that (1) cholesterol-derived markers of oxidative stress are increased in the rat jejunum in response to ethanol, indicative of metabolic damage; (2) daidzein pretreatment has protective effects against ethanol-induced injury.