Metabolic alteration of Tetrahymena thermophila exposed to CdSe/ZnS quantum dots to respond to oxidative stress and lipid damage.

CdSe/ZnS Quantum dots (QDs) are possibly released to surface water due to their extensive application. Based on their high reactivity, even small amounts of toxicant QDs will disturb water microbes and pose a risk to aquatic ecology. Here, we evaluated CdSe/ZnS QDs toxicity to Tetrahymena thermophila (T. thermophila), a model organism of the aquatic environment, and performed metabolomics experiments. Before the omics experiment was conducted, QDs were found to induce inhibition of cell proliferation, and reactive oxygen species (ROS) production along with Propidium iodide labeled cell membrane damage indicated oxidative stress stimulation. In addition, mitochondrial ultrastructure alteration of T. thermophila was also confirmed by Transmission Electron Microscope results after 48 h of exposure to QDs. Further results of metabolomics detection showed that 0.1 µg/mL QDs could disturb cell physiological and metabolic metabolism characterized by 18 significant metabolite changes, of which twelve metabolites improved and three decreased significantly compared to the control. Kyoto Encyclopedia of Genes and Genomes analysis showed that these metabolites were involved in the ATP-binding cassette transporter and purine metabolism pathways, both of which respond to ROS-induced cell membrane damage. In addition, purine metabolism weakness might also reflect mitochondrial dysfunction associated with energy metabolism and transport abnormalities. This research provides deep insight into the potential risks of quantum dots in aquatic ecosystems.

Simple strategy for sensitive detection of dopamine using CdTe QDs modified glassy carbon electrode.

BACKGROUND: Cellular and brain metabolism of dopamine can be correlated with a number of neurodegenerative disorders, our study was to explore a simple and efficient method to detect dopamine in real samples. METHODS: A new quantum dots (CdTe QDs) could be prepared using the hydrothermal method, the electrochemical biosensor was established by dropping CdTe QDs on the surface of glassy carbon electrode (GCE). RESULTS: The CdTe QDs/GCE exhibited the excellent electrochemical catalytic activity toward dopamine (DA) with good stability and high sensitivity in presence of interfering substances. The detection limit of DA was calculated by differential pulse voltammetry (DPV) as low as 0.3 µmol L-1 with a linear dynamic range of 1 µmol L-1 to 400 µmol L-1 . CONCLUSION: In this paper, the proposed electrochemical biosensor could be effectively used for the direct and rapid detection of DA in human serum and urine samples.

A Label-Free Electrochemical Biosensor Based on a Reduced Graphene Oxide and Indole-5-Carboxylic Acid Nanocomposite for the Detection of Klebsiella pneumoniae.

A label-free DNA hybridization electrochemical sensor for the detection of Klebsiella pneumoniae was developed, which could be helpful in the diagnosis of bacterial infections. Indole-5-carboxylic acid (ICA) and graphene oxide (GO) were electrodeposited on a glassy carbon electrode, and the resulting reduced GO (rGO)-ICA hybrid film served as a platform for immobilizing oligonucleotides on a single-stranded DNA (ssDNA) sequence. The conditions were optimized, with excellent electrochemical performance. A significant change was observed after hybridization of ssDNA with the target probe under optimum conditions. Hybridization with complementary, noncomplementary, one-base mismatched, and three-base mismatched DNA targets was studied effectively by differential pulse voltammetry. The proposed strategy could detect target DNA down to 3 × 10-11 M, with a linear range from 1 × 10-6 M to 1 × 10-10 M, showing high sensitivity. This electrochemical method is simple, free from indicator, and shows good selectivity. Hence, electrochemical biosensors are successfully demonstrated for the detection of K. pneumoniae.

Preparation of quantum dots CdTe decorated graphene composite for sensitive detection of uric acid and dopamine.

The assembly of quantum dots (QDs) in a simply method opens up opportunities to obtain access to the full potential of assembled QDs by virtue of the collective properties of the ensembles. In this study, quantum dots CdTe and graphene (Gr) nanocomposite was constructed for the simultaneous determination of uric acid (UA) and dopamine (DA). The CdTe QDs-Gr nanocomposite was prepared by ultrasonication and was characterized with microscopic techniques. The nanocomposite modified electrode was characterized by cyclicvoltammetry (CV), differential pulse voltammetry (DPV) and electrochemical impedance spectroscopy (EIS). Due to the synergistic effects between CdTe QDs and Gr, the fabricated electrode exhibited excellent electrochemical catalytic activities, good biological compatibility and high sensitivity toward the oxidation of UA and DA. Under optimum conditions, in the co-existence system the linear calibration plots for UA and DA were obtained over the range of 3-600 µM and 1-500 µM with detection limits of 1.0 µM and 0.33 µM. The fabricated biosensor also exhibits the excellent repeatability, reproducibility, storage stability along with acceptable selectivity.

A Highly Sensitive Oligonucleotide Hybridization Assay for Klebsiella pneumoniae Carbapenemase with the Probes on a Gold Nanoparticles Modified Glassy Carbon Electrode.

To develop a new electrochemical DNA biosensor for determination of Klebsiella pneumoniae carbapenemase, a highly sensitive and selective electrochemical biosensor for DNA detection was constructed based on a glassy carbon electrode (GCE) modified with gold nanoparticles (Au-nano). The Au-nano/GCE was characterized by scanning electromicroscopy, cyclic voltammetry, and electrochemical impedance spectroscopy. The hybridization detection was measured by differential pulse voltammetry using methylene blue as the hybridization indicator. The dynamic range of detection of the sensor for the target DNA sequences was from 1 × 10(-11) to 1 × 10(-8) M, with an LOD of 1 × 10(-12) M. The DNA biosensor had excellent specificity for distinguishing complementary DNA sequence in the presence of non-complementary and mismatched DNA sequence. The Au-nano/GCE showed significant improvement in electrochemical characteristics, and this biosensor was successfully applied for determination of K. pneumoniae.

Electrochemical DNA biosensor based on a glassy carbon electrode modified with gold nanoparticles and graphene for sensitive determination of Klebsiella pneumoniae carbapenemase.

We describe the fabrication of a sensitive electrochemical DNA biosensor for determination of Klebsiella pneumoniae carbapenemase (KPC). The highly sensitive and selective electrochemical biosensor for DNA detection was constructed based on a glassy carbon electrode (GCE) modified with gold nanoparticles (Au-NPs) and graphene (Gr). Then Au-NPs/Gr/GCE was characterized by scanning electro microscope (SEM), cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS). The hybridization detection was measured by diffierential pulse voltammetry (DPV) using methylene blue (MB) as the hybridization indicator. The dynamic range of detection of the sensor for the target DNA sequences was from 1 × 10(-12) to 1 × 10(-7)mol/L, with a detection limit of 2 × 10(-13)mol/L. The DNA biosensor had excellent specificity for distinguishing complementary DNA sequence in the presence of non-complementary and mismatched DNA sequence. The results demonstrated that the Au-NPs/Gr nanocomposite was a promising substrate for the development of high-performance electrocatalysts for determination of KPC.

Curcuminoids exert glucose-lowering effect in type 2 diabetes by decreasing serum free fatty acids: a double-blind, placebo-controlled trial.

SCOPE: We previously found that curcuminoids decreased blood glucose and improved insulin resistance by reducing serum free fatty acids (FFAs) and increasing fatty acid oxidation in skeletal muscle of diabetic rats. This study was to investigate whether curcuminoids have beneficial effects on type 2 diabetic patients, and its possible mechanisms. METHODS AND RESULTS: Overweight/obese type 2 diabetic patients (BMI ≥ 24.0; fasting blood glucose ≥ 7.0 mmol/L or postprandial blood glucose ≥11.1 mmol/L) were randomly assigned to curcuminoids (300 mg/day) or placebo for 3 months. Bodyweight, glycosylated hemoglobin A1c (HbA1c ,% ), serum fasting glucose, FFAs, lipids, and lipoprotein lipase (LPL) were determined. A total of 100 patients (curcuminoids, n = 50; placebo, n = 50) completed the trial. Curcuminoids supplementation significantly decreased fasting blood glucose (p < 0.01), HbA1c (p = 0.031), and insulin resistance index (HOMA-IR) (p < 0.01) in type 2 diabetic patients. Curcuminoids also led to a significant decrease in serum total FFAs (p < 0.01), triglycerides (P = 0.018), an increase in LPL activity (p < 0.01). CONCLUSION: These findings suggest a glucose-lowering effect of curcuminoids in type 2 diabetes, which is partially due to decrease in serum FFAs, which may result from promoting fatty acid oxidation and utilization.

Association of catalase genotype with oxidative stress in the predication of colorectal cancer: modification by epidemiological factors.

OBJECTIVE: This paper aims to assess the interaction between common variations in catalase (CAT) polymorphic gene and environmental factors for antioxidant defense enzyme in modulating individual susceptibility to colorectal cancer (CRC). METHODS: A case-control study with 880 colorectal cancer cases and 848 controls was conducted to investigate whether variations in the catalase (CAT) gene, one of the genes involved in scavenging oxidative stress, influenced susceptibility to CRC. RESULTS: The interaction between life style and genotypes as well as with their effects on colorectal cancer was deduced from the present study. Significant difference (P = 0.01) was identified in the distribution of CAT genotype between the colorectal cancer cases and the controls. The CRC cases had significantly lower mean activity than the controls (P < 0.01). Correlation analyses revealed statistically significant correlations between CAT activity and CAT genotype (P < 0.01). CONCLUSION: The risk of CRC was associated with smoking, low vegetable consumption, high pork and poultry consumptions, and low or high BMI. This is the first study reporting an association of polymorphism CAT-21A > T with colorectal cancer. Low CAT activity was associated with an increased risk of CRC; however, no evidence was found to support an association between CAT-21A > T polymorphism and CRC risk.

The oxidative stress status in diabetes mellitus and diabetic nephropathy.

The aim of this study is to assess the oxidative stress status in diabetes mellitus (DM) and diabetic nephropathy. The study group comprised 40 control subjects, 40 type 2 DM patients without complications and 37 diabetic nephropathies. Compared with control subjects, superoxide dismutase, glutathione peroxidase, catalase, vitamin C were decreased (P < 0.01). There was a significant increase in serum malondialdehyde (MDA), conjugated diene (CD), advanced oxidation protein products (AOPP), protein carbonyl (PC) and 8-hydroxy-2'-deoxyguanosine (8-OHdG) in diabetes patients when compared with normal subjects (P < 0.01). Moreover, these indexes were much higher in diabetic nephropathy than that of diabetic patients without vascular complications (P < 0.05, P < 0.01). There was a significant correlation between the serum glucose levels and PC, 8-OHdG (P < 0.05, P < 0.01). There were highly significant positive correlation of CD and MDA, AOPP and PC (P < 0.01). Plasma AOPP levels had a significant correlation with PC levels (P < 0.01). Our findings suggested that diabetes patients have more severe oxidative stress than normal persons and higher oxidative stress in diabetic nephropathy than those in patients without complications. Oxidative stress may play an important intermediary role in the pathogenesis of diabetes complications.

Evaluation of oxidative stress in colorectal cancer patients.

OBJECTIVE: To evaluate the oxidative stress in patients with colorectal cancer and to investigate the relationship between oxidative stress and colorectal cancer. METHODS: Seventy-six subjects were divided into two groups (36 colorectal cancer patients as the study group and 40 normal healthy individuals as the control group). Their protein oxidation, DNA damage, lipid peroxidation and antioxidants, vitamin C, vitamin E, glutathione (GSH), and antioxidative enzymes in serum were detected. RESULTS: The levels of protein carbonyl and advanced oxidation protein products (AOPP) were significantly higher in the study group than in the control group (P<0.01). Serum 8-OHdG was significantly increased in the study group compared to the control group (P<0.01). However, the mean serum level of MDA and conjugated diene was lower in the study group than in the control group (P<0.01). The activity of antioxidative enzymes was significantly decreased in the study group compared to the control group (P<0.01). Serum vitamins C and E concentrations were significantly reduced in the study group compared to the control group (P<0.01). CONCLUSION: Colorectal cancer is associated with oxidative stress, and assessment of oxidative stress and given antioxidants is important for the treatment and prevention of colorectal cancer.

The change of oxidative stress products in diabetes mellitus and diabetic retinopathy.

AIM: Enhanced oxidative stress contributes to the pathogenesis of diabetic retinopathy. The aim of this study is to detect oxidative stress parameters in type 2 diabetes mellitus with or without retinopathy and to investigate the relationship between oxidative stress and patients with type 2 diabetic retinopathy. METHODS: Oxidative stress parameters included malondialdehyde (MDA), conjugated diene (CD), advanced oxidation protein products (AOPP), protein carbonyl and 8-hydroxydeoxyguanosin (8-OHdG) in serum measured in 33 patients with diabetes mellitus without complications, 27 diabetes mellitus retinopathy and 32 normal control subjects, respectively. RESULTS: The concentrations of MDA and CD in type 2 diabetes mellitus (DM) were significantly higher than those of the control subjects (p<0.01). The concentration of MDA and CD in patients with retinopathy was significantly elevated in comparison with patients with diabetes without retinopathy (p<0.05). There was a significant increase in serum 8-OHdG in patients with diabetes compared with normal subjects (p<0.01), and serum 8-OHdG was much higher in diabetes mellitus retinopathy than that in patients with diabetes without retinopathy (p<0.05). This was significantly higher in serum AOPP and protein carbonyl in type 2 DM compared with normal subjects (p<0.01). Moreover, diabetes mellitus retinopathy patients had significantly higher AOPP and protein carbonyl compared with patients with diabetes without retinopathy (p<0.05). CONCLUSIONS: These results indicate that there were severe lipid peroxidation, protein oxidation, and oxidative DNA damage in diabetes. The augmented oxidative stress in diabetes may be speculated to contribute to the pathogenesis of diabetes mellitus. Oxidative stress is an important risk factor in the development of diabetic retinopathy. The levels and the types of serum oxidative stress by-products will be in favour of predicting the amount of retinopathy.

Oxidative damage to DNA and its relationship with diabetic complications.

OBJECTIVE: To detect the oxidative DNA damage in diabetic patients and to investigate the relationship of oxidative DNA damage with diabetes and diabetic nephropathy. METHODS: Single cell gel electrophoresis (SCGE) was used to detect the DNA strand breaks in peripheral blood lymphocytes, and oxidative DNA damage product and serum 8-OHdG were determined by a competitive ELISA in 47 cases, including 25 patients without diabetic complications, 22 patients with diabetic nephropathy and 25 normal control subjects. RESULTS: Diabetic patients showed greater oxidative damage to DNA. The percentage of comet cells and the length of DNA migration (comet tail length) of peripheral blood lymphocytes were significantly increased in patients with diabetes, and significantly higher in patients with diabetic nephropathy than in diabetic patients without vascular complications (P < 0.05). There was a significant increase in serum 8-OHdG in diabetic patients compared with normal subjects (P < 0.05). Moreover, serum 8-OHdG was much higher in patients with diabetic nephropathy than in diabetic patients without vascular complications (P < 0.05). CONCLUSION: There is severe oxidative DNA damage in diabetic patients. Enhanced oxidative stress may be associated with diabetes, especially in patients with diabetic nephropathy.

[Effect of yeast RNA on physical functions, morphology of hepatic cells and brain neurons in aged rats].

OBJECTIVE: To study the effect of exogenous nucleic acid on physical functions, morphology of hepatic cells and brain neurons in aged rats. METHODS: Thirty two aged Wistar rats (20 month-old) were divided randomly into four groups (one aged control group and three aged experimental groups) and eight young rats (3 month-old) was set as young control group. Control groups were fed on standard chow and experimental groups were fed on standard chow supplemented with 93.75 mg/kg (high-dosage group), 46.88 mg/kg (middle-dosage group) and 9.38 mg/kg (low-dosage group) of yeast RNA respectively. SOD, MDA, HDL, sex hormone and growth hormone were determined at the end of a 4-week observation. The microcosmic images of the hepatic cells and brain neurons using the image-pro plus (V.4.0) were also observed. RESULTS: SOD, serum HDL and growth hormone levels in the high dosage group were significantly higher (P < 0.05) than that in the aged control group, and the levels were not different from that in the young control group. MDA level of all yeast RNA supplemented groups was significantly lower than that of aged control group (P < 0.05) and that was not different from the young control group. Serum testosterone of the high and middle dosage groups reached the level of young control group, and that was much higher than the aged control and low dosage group (P < 0.05). Estradiol levels among the aged rats were not different, and those were much lower than the young control group (P < 0.05). Much more number of brain neurons were observed in the high-dose group than other aged rats (P < 0.05). Brain neurons, hepatic cells and karyons in the high-dose group were bigger than that in other aged rats (P < 0.05). CONCLUSION: Exogenous yeast RNA might play an important role in physical functions, the morphology of brain neurons and hepatic cells in natural aged rats. There might have a dose-effect relationship in the process.

[Development of a new biosensor for biochemical oxygen demand].

OBJECTIVE: To use a new kind of fixing material, i.e. Sol-Gel organic-inorganic hybridized material to immobilize bacterium to detect Biochemical oxygen demand quickly. METHODS: The biosensor was fabricated using a thin film in which Hansenula anomala was immobilized by sol-gel and an oxygen electrode. The optimum measurement for biochemical oxygen demand was at pH 7.0; 28 degrees C; response time 3 - 12 min. Pure organic compound, sewage and rate of recovery were detected with the biosensor. RESULTS: It shows that the BOD biosensor can be used to detect many organic compounds such as amino acid, glucide. It is suitable to monitor sewage and industrial waste water which has low level alcohols and phenols. The microbial membrane can work 3 months and remain its 70% activity. It is measured that the rate of recovery of BOD is between 90% to 105% in sewage. CONCLUSION: The study confirmed the effectiveness and usefulness of BOD sensor, which is quick, convenient, low cost and reliable with little interference.

[DNA damage and changes of antioxidative enzymes in chronic benzene poisoning mice].

OBJECTIVE: To study the damage effect of benzene on DNA and its mechanism and the changes of antioxidative enzymes in vivo. METHODS: DNA break in bone marrow cells and peripheral blood lymphocytes of mice exposed to benzene by 4 h static inhalation per day at different concentrations for two months were analyzed with single cell gel electrophoresis (SCGE). Meanwhile, the activity of SOD, GSH-Px and the level of MDA in liver, spleen and brain were detected. RESULTS: In low and high dosage groups, the rate of DNA migration of bone marrow cells (83.56% +/- 10.28%, 92.54% +/- 15.93%) and peripheral blood lymphocytes (41.27% +/- 6.03%, 65.79% +/- 11.62%) were higher than those in control (4.13% +/- 0.52% and 2.21% +/- 0.31% respectively, P<0.05]. The activity of SOD in liver [(754.33 +/- 116.30), (694.26 +/- 116.30) U/mg pro] and GSH-Px [(22.52 +/- 3.31), (18.56 +/- 4.97) U/mg pro] were lower than those in control [(999.92 +/- 188.24) and (35.31 +/- 6.63) U/mg pro respectively, P<0.05, P<0.01]. But there was no significant difference between the two dosage groups. The activity of GSH-Px in spleen of both groups [(31.38 +/- 2.71), (25.30 +/- 7.44) U/mg pro] were lower than that of control [(37.11 +/- 3.42) U/mg pro, P<0.05] and there was significant difference between the two dosage groups. The activity of GSH-Px in brain of both groups [(5.70 +/- 0.84), (5.24 +/- 1.19) U/mg pro, P<0.05] were lower than that of control [(7.10 +/- 0.46) U/mg pro, P<0.05], but there was no significant difference between the two dosage groups. The level of MDA in brain of high dosage group [(3.99 +/- 1.15) nmol/mg pro] was higher than that of control [(2.58 +/- 0.53) nmol/mg pro, P<0.05]. CONCLUSION: Chronic benzene poisoning may result in DNA break in bone marrow cells and peripheral blood lymphocytes and decrease in the activity of antioxidative enzymes.