Electronic structures and optical properties for Ag-N-codoped ZnO nanotubes.

The structural and electronic/optical properties of pure and Ag-N-codoped (8,0) ZnO nanotubes have been studied using first-principles calculations in the framework of the local spin density approximation. The configurations for Zn atoms replaced by Ag atoms are p-type semiconductor materials, and the bandgap increases when N atoms are doped into ZnO nanotube configurations. The optical studies based on dielectric function and reflectivity indicate that new transition peaks in the visible light range are observed, which can be ascribed to the Ag and N doping. Furthermore, there is a red shift observed with the increase of N concentration.

Antihypoxic effects of neuroglobin in hypoxia-preconditioned mice and SH-SY5Y cells.

This work aims at investigating the neuroprotective effects of neuroglobin (Ngb) in vivo and in vitro. RT-PCR and Western blotting were used to examine Ngb mRNA and protein levels in the mouse cortex after acute and repeated exposure to hypoxia. The cDNAs of mouse Ngb were cloned and transfected into SH-SY5Y cells to examine Ngb function in vitro. Expression of Ngb and mRNA was upregulated in the cortex of mice preconditioned by repetitive exposure to hypoxia. Tolerance to hypoxia of Ngb-transformed SH-SY5Y cells was enhanced. These results suggest that Ngb might be involved in hypoxic preconditioning which protects neurons from hypoxic injury.

[Determination of meconium lead level of newborn by graphite furnace atomic absorption spectrometry].

UNLABELLED: To establish a method for the determination of lead in meconium from 144 samples of newborn through nitric acid digestion by means of graphite furnace atomic absorption spectrometry. METHODS: after being baked for at least 12 h at 60 degrees C, 0.3 g of meconium was digested by nitric acid and hydrogen peroxide in turn at 80 degrees C under water-bath condition for 1h and then metered to the whole volume of to 2 mL. After correcting the background with D2 lamp, specimen basal corpuscle matched standard curve was used to detect the lead content. RESULTS: The mean lead content of 93 experimental samples was 1.934 microg x g(-1) with the standard deviation (SD) of 1.551, and that of the 51 control samples was 1.012 microg x g(-1), with the SD of 1.084. There was a significant difference in lead levels of in meconnt between the experimental group and control group (p = 0.000). CONCLUSION: The lead content of the experimental was significantly higher than that of the control group detected by this method. This method was stable and efficient.

[Recombinant prokaryotic plasmid construction and high expression of FUS1 gene].

OBJECTIVE: To construct the prokaryotic plasmid of FUS1 gene for efficient FUS1 expression in E.coli strain Rosetta(DE3)2plys. METHODS: The full-length FUS1 gene was amplified by PCR from the total RNA of umbilical mesenchymal stem cells and cloned into pET-32a(+) vector followed by identification with PCR and sequencing. The recombinant plasmid pET-32a(+)-FUS1 was transformed into the E.coli strain Rosetta(DE3)2plys and the target protein expression was induced by IPTG. RESULTS: The plasmid pET-32a(+)-FUS1 was obtained successfully as verified by PCR and sequence analysis. High expression of the fused FUS1 protein was achieved after induction by low-concentration IPTG (25 micromol/L) for 3 h, and the recombinant FUS1 protein accounted for 40% of the total bacterial protein of Rosetta(DE3)2plys. CONCLUSION: The recombinant FUS1 plasmid has been successfully cloned, which allows highly efficient FUS1 expression in Rosetta (DE3)2 plys.

Size-dependent orientation growth of large-area ordered Ni nanowire arrays.

Large-area ordered Ni nanowire arrays with different diameters have been fabricated by the direct current electrodeposition into the holes of porous anodic alumina membrane. The crystal structure and micrograph of nanowire arrays are characterized by X-ray diffraction, field-emission scanning electron microscopy and high-resolution transmission electron microscopy. The results indicate that the growth orientation of Ni nanowires turns from [110] to [111] direction with increasing diameters of nanowires. The mechanism of the growth was discussed in terms of interface energy minimum principle. The size-dependent orientation of Ni nanowire arrays has the important significance for the design and control of nanostructures.

Filamentous-actins in human hepatocarcinoma cells with CLSM.

AIM: To establish a method for optical sections of HepG2 human hepatoblastoma cells with confocal laser scanning microscope (CLSM) and to study the spatial structure of filamentous actin (F-actin) in HepG2 cells. METHODS: HepG2 cells were stained with FITC-phalloidin that specifically binds F-actin, with propidium iodide (PI) to the nucleus, and scanned with a CLSM to generate optically sectioned images. A series of optical sections taken successively at different focal levels in steps of 0.7 microm were reconstructed with the CLSM reconstruction program. RESULTS: CLSM images showed that the FITC-stained F-actin was abundant microfilament bundles parallel or netted through the whole cell and its processes. Most F-actin microfilaments extended through the cell from one part toward the other or run through the process. Some microfilaments were attached to the plasma membrane, or formed a structural bridge connecting to the neighboring cells. CONCLUSION: A method for double labeling HepG2 human hepatoblastoma cells and CLSM imaging F-actin microfilaments and nuclei by image thin optical sections and spatial structure was developed. It provides a very useful way to study the spatial structure of F-actin.

Autophagy of neuron axon during regeneration of rat sciatic nerves.

OBJECTIVE: To investigate the autophagic clearance of degenerated neuron axon during regeneration of rat sciatic nerves. METHODS: Wallerian degeneration model was established in rats by sciatic nerve transection. Samples from the distal stump were collected at different time points after the transaction and ultrathin sections prepared for electron microscopic examination and acid phosphatase (AcPase) activity detection. RESULTS: Neuron axon degeneration occurred after transection of rat sciatic nerve, presenting predominantly swelling of the axoplasm and separation of the axon from the myelin sheath seen 5 h to 2 d after the transection. On day 4, axoplasm condensation took place and the axons were completely separated from the myelin sheath to form dissociative axon body. Vacuoles of various sizes were identified in the axon in the early stage after operation and later when the axons were completely dissociated from the nerve sheath, larger dissociative axon bodies occurred. The axolemma surrounding the axon body was derived from the neuronal cytomembrane, and the condensed axoplasm contained numerous autophagic vacuoles at all levels along with large number of neurofilaments, microtubules and microfilaments arranged in a crisscross pattern. The autophagic vacuoles exhibited acid phosphatase (AcPase) activities. Since the day 7, the axon bodies were absorbed after degradation and macrophages could be spotted occasionally. CONCLUSION: The degenerated axons were cleared mainly through autophagy during regeneration of rat sciatic nerve and macrophages only assist in this process.

[Effect of human hair keratin implant on oligodendrocyte proliferation and differentiation in rats with acute spinal cord injury].

OBJECTIVE: To investigate the changes of oligodendrocyte proliferation and differentiation in response to implantation of degradable human hair keratin (HHK) into the spinal cord with acute injury in adult rats. METHOD: Rat models of acute spinal cord injury were established by direct impact of the exposed spinal cord with a weight-dropping device, 12 of which received immediate HHK implant into the injured spinal cord. The rats of control injury group (n=12) were subjected to the injury but did not receive subsequent implant, and those in sham operation group (n=12) only had the spinal cord exposure without injury. Another 8 rats were used as the normal control group. Samples of the spinal cord were obtained 1, 4, 12, and 26 weeks respectively after the operations and serial sections were prepared for examination with light and electron microscope. RESULTS: One week after the injury, few oligodendrocytes were observed among the large number of the infiltrating leukocytes in the injured spinal cord with HHK implants. Staining with hematoxylin eosin and Mallory's phosphotungstic acid-hematoxylin at the fourth week revealed oligodendrocyte proliferation around the HHK implant. The period from the 12th to 26th week was characterized by nerve regeneration and myelin sheath reconstruction, in the course of which empty cavity occurred within the sheath of the oligodendrocytes, and lamellar separation of the myelin sheath were observed. Phagocytized myelin sheath and axone fragment were detected in oligodendrocytes, with the newly generated oligodendrocytes scattering abound the rebuilt myelin sheath. CONCLUSION: HHK can be beneficial for the proliferation and differentiation of oligodendrocytes and myelin sheath rebuilding and repair in the course of neuronal regeneration after acute spinal cord injury.

[Ultrastructural observation of rat thymus tissue with coronavirus infection].

OBJECTIVE: To investigate the ultrastructure of rat thymus tissues with rat coronavirus (RCV) infection for clarifying the mechanism responsible for the morphological changes of the cells infected by RCV. METHODS: Routine electron microscopy was performed for observing RCV-infected rat thymus tissues. RESULTS: Following RCV infection, endoplasmic reticulum (ER) pools of different dimensions were observed in the cytoplasm of the thymic epithelial reticular cells, merging subsequently with each other into larger ER lakes filled with particles of mature RCV, or viral inclusion bodies. After germination on the ER membrane, the viruses entered the matrix of the ER lake to mature and were eventually excreted to the extracellular space. The RCV particles were spherical in shape with a diameter of 100-130 nm and two distinct membranes, the outer one being the envelope and the inner one the nuclear capsid to enclose the viroplasm. Between the envelop and nuclear capsid was a electron-lucent middle layer comprising one to two thin membranous structures. Large quantity of short spike-like projections starting from the nucleus capsid penetrated the middle layer and the envelop to reach the glycoprotein coat and formed a corona-like structure. Mature RCV particles were distributed around the ER pools, cytoplasm, and intercellular space, and the RCVs in the endosome/lysosome were devoid of the envelop and nuclear capsid. CONCLUSION: The ER lakes are involved in the maturation of the viruses, and the envelop and nuclear capsid of the virus entering the cells from extracellular space are removed and degraded in the endosome/lysosome. Replications of virus occurs in plasma of the thymic epithelial reticular cells, and no RCV can be detected in the thymocytes.