Showing papers by "Feng Zhang published in 2004"

Assembly of endocytic machinery around individual influenza viruses during viral entry

Abstract: Most viruses enter cells via receptor-mediated endocytosis. However, the entry mechanisms used by many of them remain unclear. Also largely unknown is the way in which viruses are targeted to cellular endocytic machinery. We have studied the entry mechanisms of influenza viruses by tracking the interaction of single viruses with cellular endocytic structures in real time using fluorescence microscopy. Our results show that influenza can exploit clathrin-mediated and clathrin- and caveolin-independent endocytic pathways in parallel, both pathways leading to viral fusion with similar efficiency. Remarkably, viruses taking the clathrin-mediated pathway enter cells via the de novo formation of clathrin-coated pits (CCPs) at viral-binding sites. CCP formation at these sites is much faster than elsewhere on the cell surface, suggesting a virus-induced CCP formation mechanism that may be commonly exploited by many other types of viruses.

Genetic evidence supports demic diffusion of Han culture

Abstract: The spread of culture and language in human populations is explained by two alternative models: the demic diffusion model, which involves mass movement of people; and the cultural diffusion model, which refers to cultural impact between populations and involves limited genetic exchange between them. The mechanism of the peopling of Europe has long been debated, a key issue being whether the diffusion of agriculture and language from the Near East was concomitant with a large movement of farmers. Here we show, by systematically analysing Y-chromosome and mitochondrial DNA variation in Han populations, that the pattern of the southward expansion of Han culture is consistent with the demic diffusion model, and that males played a larger role than females in this expansion. The Han people, who all share the same culture and language, exceed 1.16 billion (2000 census), and are by far the largest ethnic group in the world. The expansion process of Han culture is thus of great interest to researchers in many fields.

Chemical composition and biocompatibility of Ti–Ag–O films prepared by ion beam assisted deposition

Abstract: Titanium oxides are considered as blood compatible surfaces, however, it may be possible to improve the compatibility to the inner lining cells of blood vessels by addition of Ag which modifies the electronic properties of this oxide. Therefore, Ti–Ag–O films with the thickness of 200–350 nm have been deposited on Si substrates using an ion beam assisted deposition (IBAD) system which has two evaporators to allow a simultaneous deposition of Ti and Ag. The evaporation rates of Ti and Ag, as well as the flow rate of O2 have varied. For physicochemical analysis of the films, glancing incidence X-ray diffraction (GIXRD) analysis, X-ray photoelectron spectroscopy (XPS) and Auger electron spectroscopy (AES) were performed. The formed phases in Ti–Ag–O films consist of TiO2, AgO, Ag2O, Ag, TiAg, AgTi3, and low valent titanium oxides. The bovine aortic endothelial cell line GM07373 was grown on these surfaces in a medium with 10% fetal bovine serum. The toxicity of the layers was rated by the release of lactate dehydrogenase (LDH) from the cells and are found to be below the detection limit; the cell adhesion was investigated by fluorescent staining of the adhesion molecule vinculin and the cytoskeleton protein filamentary actin; the cell nuclei were counterstained with DAPI, showing good cell adherence, good compatibility to endothelial cells, and no indication of apoptotic cell death.

Reduced nitric oxide in the rostral ventrolateral medulla enhances cardiac sympathetic afferent reflex in rats with chronic heart failure.

Abstract: The purpose of this study was to determine the effect of nitric oxide (NO) in the rostral ventrolateral medulla (RVLM) on the central integration of the cardiac sympathetic afferent reflex (CSAR) in normal rats and in rats with coronary ligation-induced chronic heart failure (CHF). Under alpha-chloralose and urethane anesthesia, mean arterial pressure, heart rate and renal sympathetic nerve activity (RSNA) were recorded at baseline and during elicitation of the CSAR evoked by electrical stimulation of the cardiac afferent sympathetic nerves in sino-aortic denervated and cervical vagotomized rats. A cannula was inserted into the left RVLM for microinjection of NO synthase inhibitor, S-methyl-L-thiocitruline (MeTC) or NO donor, S-nitroso-N-acetyl-penicillamine (SNAP). The CSAR was tested by electrical stimulation (5, 10, 20 and 30 Hz at 10 V for 1 ms) of the afferent cardiac sympathetic nerves. It was observed that (1) the responses of RSNA to stimulation were enhanced in rats with CHF; (2) MeTC (80 nmol) potentiated the responses of RSNA to stimulation in sham rats but not in rats with CHF; (3) SNAP (50 nmol) depressed the enhanced RSNA response to stimulation in CHF rats but had no effect in sham rats; and (4) MeTC increased the baseline RSNA and MAP only in sham rats, but SNAP inhibited the baseline RSNA and MAP in both sham and CHF rats. These results indicate that reductance of NO in the RVLM is involved in the augmentation of CSAR in CHF rats.