CdSe Quantum Dot (QD)-Induced Morphological and Functional Impairments to Liver in Mice

Quantum dots (QDs), as unique nanoparticle probes, have been used in in vivo fluorescence imaging such as cancers. Due to the novel characteristics in fluorescence, QDs represent a family of promising substances to be used in experimental and clinical imaging. Thus far, the toxicity and harmful health effects from exposure (including environmental exposure) to QDs are not recognized, but are largely concerned by the public. To assess the biological effects of QDs, we established a mouse model of acute and chronic exposure to QDs. Results from the present study suggested that QD particles could readily spread into various organs, and liver was the major organ for QD accumulation in mice from both the acute and chronic exposure. QDs caused significant impairments to livers from mice with both acute and chronic QD exposure as reflected by morphological alternation to the hepatic lobules and increased oxidative stress. Moreover, QDs remarkably induced the production of intracellular reactive oxygen species (ROS) along with cytotoxicity, as characterized by a significant increase of the malondialdehyde (MDA) level within hepatocytes. However, the increase of the MDA level in response to QD treatment could be partially blunted by the pre-treatment of cells with beta-mercaptoethanol (β-ME). These data suggested ROS played a crucial role in causing oxidative stress-associated cellular damage from QD exposure; nevertheless other unidentified mediators might also be involved in QD-mediated cellular impairments. Importantly, we demonstrated that the hepatoxicity caused by QDs in vivo and in vitro was much greater than that induced by cadmium ions at a similar or even a higher dose. Taken together, the mechanism underlying QD-mediated biological influences might derive from the toxicity of QD particles themselves, and from free cadmium ions liberated from QDs as well

Finishing the euchromatic sequence of the human genome

The sequence of the human genome encodes the genetic instructions for human physiology, as well as rich information about human evolution. In 2001, the International Human Genome Sequencing Consortium reported a draft sequence of the euchromatic portion of the human genome. Since then, the international collaboration has worked to convert this draft into a genome sequence with high accuracy and nearly complete coverage. Here, we report the result of this finishing process. The current genome sequence (Build 35) contains 2.85 billion nucleotides interrupted by only 341 gaps. It covers ∼99% of the euchromatic genome and is accurate to an error rate of ∼1 event per 100,000 bases. Many of the remaining euchromatic gaps are associated with segmental duplications and will require focused work with new methods. The near-complete sequence, the first for a vertebrate, greatly improves the precision of biological analyses of the human genome including studies of gene number, birth and death. Notably, the human enome seems to encode only 20,000-25,000 protein-coding genes. The genome sequence reported here should serve as a firm foundation for biomedical research in the decades ahead

The Rattling and Rotation Behaviours of the Hydrated Excess Proton in Water

The rattling and rotation behaviours of the hydrated excess proton (H+) in water are investigated using the density functional theory–quantum chemical cluster model (DFT-CM) method. The rattling pathways for the target proton *H+ between two adjacent O atoms in the form of Zundel configurations with symmetrical solvation environments are obtained. The zero-point contribution reduces the reaction energy barrier and enables the rattling to occur spontaneously at room temperature. The rotational behaviour of *H+ in the form of *H+·H2O* is found. Upon *H+·H2O* rotation, *H+ changes its position accompanied by concerted displacement of surrounding solvent water molecules and the breaking and formation of hydrogen bonds. The “*H+·H2O* rotating migration mechanism” is proposed for the proton transfer mechanism in water — the same *H+ migrates via *H+·H2O* rotation through void in solvent water, rather than different protons hopping along water hydrogen bond chains as known as the Grotthuss mechanism. </p

Electrochemical Studies of the Inhibition and Activation Effects of Al (III) on the Activity of Bovine Liver Glutamate Dehydrogenase

Since the study of Al3+ ion on the enzyme activity by using of electrochemical techniques was rarely found in available literatures, the differential-pulse polarography (DPP) technique was applied to study the effects of Al3+ ion on the glutamate dehydrogenase (GDH) activity in the catalytical reaction of α-KG +NADH+NH4 + ⇔ L-Glu+NAD++H2O by monitoring the DPP reduction current of NAD+. At the plant and animal physiologically relevant pH values (pH=6.5 and 7.5), the GDH enzyme activities were strongly depended on the concentrations of the metal ion in the assay mixture solutions. In the lower Al (III) concentration solutions (<30 μM), the inhibitory effects were shown, which are in accordance with the recently biological findings. With the increase of Al (III) concentrations (30~80 μM), the enzyme GDH activities were activated. However, once the concentration of Al (III) arrived to near 0.1 mM level (>80μM), the inhibition effects of Al (III) were shown again. The cyclic voltammetry of NAD+ and NAD+-GDH in the presence of Al (III) can help to explain some biological phenomena. According to the differential-pulse polarography and cyclic voltammetry experiments, the present research confirmed that the electrochemical technique is a convenient and reliable sensor for accurate determination of enzyme activity in biological and environmental samples