Showing papers by "Sun Yat-sen University published in 2003"

Reactive Oxygen Species-Regulated Signaling Pathways in Diabetic Nephropathy

Abstract: Diabetic nephropathy is characterized by excessive deposition of extracellular matrix (ECM) in the kidney. TGF-beta1 has been identified as the key mediator of ECM accumulation in diabetic kidney. High glucose induces TGF-beta1 in glomerular mesangial and tubular epithelial cells and in diabetic kidney. Antioxidants inhibit high glucose-induced TGF-beta1 and ECM expression in glomerular mesangial and tubular epithelial cells and ameliorate features of diabetic nephropathy, suggesting that oxidative stress plays an important role in diabetic renal injury. High glucose induces intracellular reactive oxygen species (ROS) in mesangial and tubular epithelial cells. High glucose-induced ROS in mesangial cells can be effectively blocked by inhibition of protein kinase C (PKC), NADPH oxidase, and mitochondrial electron transfer chain complex I, suggesting that PKC, NADPH oxidase, and mitochondrial metabolism all play a role in high glucose-induced ROS generation. Advanced glycation end products, TGF-beta1, and angiotensin II can also induce ROS generation and may amplify high glucose-activated signaling in diabetic kidney. Both high glucose and ROS activate signal transduction cascade (PKC, mitogen-activated protein kinases, and janus kinase/signal transducers and activators of transcription) and transcription factors (nuclear factor-kappaB, activated protein-1, and specificity protein 1) and upregulate TGF-beta1 and ECM genes and proteins. These observations suggest that ROS act as intracellular messengers and integral glucose signaling molecules in diabetic kidney. Future studies elucidating various other target molecules activated by ROS in renal cells cultured under high glucose or in diabetic kidney will allow a better understanding of the final cellular responses to high glucose.

Systematic synthesis and characterization of single-crystal lanthanide orthophosphate nanowires.

Abstract: A simple hydrothermal method has been developed for the systematic synthesis of lanthanide orthophosphate crystals with different crystalline phases and morphologies. It has been shown that pure LnPO4 compounds change structure with decreasing Ln ionic radius: i.e., the orthophosphates from Ho to Lu as well as Y exist only in the tetragonal zircon (xenotime) structure, while the orthophosphates from La to Dy exist in the hexagonal structure under hydrothermal treatment. The obtained hexagonal structured lanthanide orthophosphate LnPO4 (Ln = La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, and Dy) products have a wirelike morphology. In contrast, tetragonal LnPO4 (Ln = Ho, Er, Tm, Yb, Lu, Y) samples prepared under the same experimental conditions consist of nanoparticles. The obtained hexagonal LnPO4 (Ln = La → Tb) can convert to the monoclinic monazite structured products, and their morphologies remained the same after calcination at 900 °C in air (Hexagonal DyPO4 is an exceptional case, it transformed to tetragonal DyPO...

Interactions of herbs with cytochrome P450.

Abstract: A resurgence in the use of medical herbs in the Western world, and the co-use of modern and traditional therapies is becoming more common. Thus there is the potential for both pharmacokinetic and pharmacodynamic herb-drug interactions. For example, systems such as the cytochrome P450 (CYP) may be particularly vulnerable to modulation by the multiple active constituents of herbs, as it is well known that the CYPs are subject to induction and inhibition by exposure to a wide variety of xenobiotics. Using in vitro, in silico, and in vivo approaches, many herbs and natural compounds isolated from herbs have been identified as substrates, inhibitors, and/or inducers of various CYP enzymes. For example, St. John's wort is a potent inducer of CYP3A4, which is mediated by activating the orphan pregnane X receptor. It also contains ingredients that inhibit CYP1A2, CYP2C9, CYP2C19, CYP2D6, and CYP3A4. Many other common medicinal herbs also exhibited inducing or inhibiting effects on the CYP system, with the latter being competitive, noncompetitive, or mechanism-based. It appears that the regulation of CYPs by herbal products complex, depending on the herb type, their administration dose and route, the target organ and species. Due to the difficulties in identifying the active constituents responsible for the modulation of CYP enzymes, prediction of herb-drug metabolic interactions is difficult. However, herb-CYP interactions may have important clinical and toxicological consequences. For example, induction of CYP3A4 by St. John's wort may partly provide an explanation for the enhanced plasma clearance of a number of drugs, such as cyclosporine and innadivir, which are known substrates of CYP3A4, although other mechanisms including modulation of gastric absorption and drug transporters cannot be ruled out. In contrast, many organosulfur compounds, such as diallyl sulfide from garlic, are potent inhibitors of CYP2E1; this may provide an explanation for garlic's chemoproventive effects, as many mutagens require activation by CYP2E1. Therefore, known or potential herb-CYP interactions exist, and further studies on their clinical and toxicological roles are warranted. Given that increasing numbers of people are exposed to a number of herbal preparations that contain many constituents with potential of CYP modulation, high-throughput screening assays should be developed to explore herb-CYP interactions.

A DWT-DFT composite watermarking scheme robust to both affine transform and JPEG compression

Abstract: Robustness is a crucially important issue in watermarking. Robustness against geometric distortion and JPEG compression at the same time with blind extraction remains especially challenging. A blind discrete wavelet transform-discrete Fourier transform (DWT-DFT) composite image watermarking algorithm that is robust against both affine transformation and JPEG compression is proposed. The algorithm improves robustness by using a new embedding strategy, watermark structure, 2D interleaving, and synchronization technique. A spread-spectrum-based informative watermark with a training sequence is embedded in the coefficients of the LL subband in the DWT domain while a template is embedded in the middle frequency components in the DFT domain. In watermark extraction, we first detect the template in a possibly corrupted watermarked image to obtain the parameters of an affine transform and convert the image back to its original shape. Then, we perform translation registration using the training sequence embedded in the DWT domain, and, finally, extract the informative watermark. Experimental work demonstrates that the proposed algorithm generates a more robust watermark than other reported watermarking algorithms. Specifically it is robust simultaneously against almost all affine transform related testing functions in StirMark 3.1 and JPEG compression with quality factor as low as 10. While the approach is presented for gray-level images, it can also be applied to color images and video sequences.

Helical Ribbons of Cadmium(II) and Zinc(II) Dicarboxylates with Bipyridyl- Like Chelates Syntheses, Crystal Structures and Photoluminescence

Abstract: Four mixed-ligand complexes of [M(mpa)(phen)]n [M =C d (1 )o r Zn (2) and mpa = m-phthalate and phen = 1,10-phenanthroline) and [M2(mpa)2(2,2-bpy)2]n [M = Zn (3 )o r Cd (4) and 2,2-bpy = 2,2-bipyridine] have been synthesized and their crystal structures have been established by single-crystal X-ray diffraction. They all consist of one-dimensional ribbons featuring dinuclear units. Both 1 and 2 crystallize isomorphously in the monoclinic space group P2/c and feature

Self‐help in housing and chengzhongcun in China's urbanization

Abstract: This article focuses on the housing issues of rural migrants arising from urbanization, with particular reference to chengzhongcun, a topic with considerable impact on policymaking. An attempt is made to understand the underlying rationale of self-help in housing and the important role of chengzhongcun in sheltering rural migrants in the context of China's rural-urban dichotomy. As demonstrated in this study, chengzhongcun accommodate, with little in the way of government resources and assistance, millions of rural migrants because of their social accessibility and affordability. While not denying their social problems, we argue that chengzhongcun in fact act as an innovative and positive agent to promote urbanization in present day China by housing massive numbers of rural migrants and assimilating them into cities. Current government policies towards chengzhongcun have generated a wide range of interest conflicts and confrontations. The consequences of such conflicts show that the government policies were problematic and unworkable, as they violated basic market principles as well as citizen rights. Policy strategy towards the redevelopment of chengzhongcun must acknowledge their credibility in the Chinese road to urbanization and requires more thoughtful and prudent consideration of migrants' demands for affordable housing. Cet article traite des problemes de logement que rencontrent les migrants ruraux du fait de l'urbanisation, et s'attache aux chengzhongcun, sujet epineux de la politique publique. L'etude tente de comprendre pourquoi les migrants ruraux doivent se debrouiller par eux-memes pour se loger, et pourquoi les chengzhongcun sont importants pour leur hebergement dans le cadre de la dichotomie chinoise villecampagne. Avec une aide et des ressources gouvernenmentales minimes, les chengzhongcun abritent des millions de ces migrants grâce a la nature sociale de leur acces et de leur cout. Sans nier leurs problemes sociaux, l'article affirme que les chengzhongcun ont en fait une action innovante et positive dans la promotion de l'urbanisation contemporaine en Chine, en logeant un tres grand nombre de migrants ruraux tout en les assimilant dans les villes. Les politiques gouvernmentales actuelles a l'egard des chengzhongcun ont genere toute une gamme de conflits d'interets et de confrontations. Leurs consequences montrent que ces politiques problematiques ont ete impraticables, puisqu'elles enfreignaient a la fois les principes de base du marche et les droits des citoyens. Une strategie politique en faveur de la renovation des chengzhongcun doit reconnaitre leur credibilite sur la voie de l'urbanisation en Chine, et exige une prise en consideration plus prudente et refleechie des demandes de logement accessible financierement par les migrants.

Embryonic stem cells generated by nuclear transfer of human somatic nuclei into rabbit oocytes

Abstract: To solve the problem of immune incompatibility, nuclear transplantation has been envisaged as a means to produce cells or tissues for human autologous transplantation. Here we have derived embryonic stem cells by the transfer of human somatic nuclei into rabbit oocytes. The number of blastocysts that developed from the fused nuclear transfer was comparable among nuclear donors at ages of 5, 42, 52 and 60 years, and nuclear transfer (NT) embryonic stem cells (ntES cells) were subsequently derived from each of the four age groups. These results suggest that human somatic nuclei can form ntES cells independent of the age of the donor. The derived ntES cells are human based on karyotype, isogenicity, in situ hybridization, PCR and immunocytochemistry with probes that distinguish between the various species. The ntES cells maintain the capability of sustained growth in an undifferentiated state, and form embryoid bodies, which, on further induction, give rise to cell types such as neuron and muscle, as well as mixed cell populations that express markers representative of all three germ layers. Thus, ntES cells derived from human somatic cells by NT to rabbit eggs retain phenotypes similar to those of conventional human ES cells, including the ability to undergo multilineage cellular differentiation.

Effects of Ganopoly® (A Ganoderma lucidum Polysaccharide Extract) on the Immune Functions in Advanced‐Stage Cancer Patients

Abstract: Preclinical studies have established that the Ganoderma lucidum polysaccharide (GLPS) fractions have potent anti‐tumor activity, which has been associated with the immuno‐stimulating effects of GLP...

An efficient forward-backward algorithm for an explicit-duration hidden Markov model

Abstract: Existing algorithms for estimating the model parameters of an explicit-duration hidden Markov model (HMM) usually require computations as large as O((MD/sup 2/ + M/sup 2/)T) or O(M/sup 2/ DT), where M is the number of states; D is the maximum possible interval between state transitions; and T is the period of observations used to estimate the model parameters. Because of such computational requirements, these algorithms are not practical when we wish to construct an HMM model with large state space and large explicit state duration and process a large amount of measurement data to obtain high accuracy. We propose a new forward-backward algorithm whose computational complexity is only O((MD + M/sup 2/)T), a reduction by almost a factor of D when D > M and whose memory requirement is O(MT). As an application example, we discuss an HMM characterization of access traffic observed at a large-scale Web site: we formulate the Web access pattern in terms of an HMM with explicit duration and estimate the model parameters using our algorithm.

Chymase is upregulated in diabetic nephropathy: implications for an alternative pathway of angiotensin II-mediated diabetic renal and vascular disease.

Abstract: Angiotensin II (AngII) has been shown to play a critical role in diabetic nephropathy and vasculopathy. Although it is well recognized that an angiotensin-converting enzyme (ACE)-dependent AngII-generating system is a major source of intrarenal AngII production, it is here reported that the chymase-dependent AngII-generating system is upregulated in the human diabetic kidney. This becomes particularly strong in those with hypertension. In the normal kidney, while ACE was constitutively expressed by most kidney cells, chymase was weakly expressed by mesangial cells (MC) and vascular smooth muscle cells (VSMC) only. In the diabetic kidney, while ACE expression was significantly upregulated (1 to 3-fold) by tubular epithelial cells (TEC) and infiltrating mononuclear cells, there was also markedly increased chymase expression (10 to 15-fold) by both MC and VSMC, with strong deposition in the collagen-rich extracellular matrix including both diffuse and nodular glomerulosclerosis, tubulointerstitial fibrosis, and vascular sclerosis. Interestingly, while ACE expression showed no difference in patients with or without hypertension, upregulation of chymase in hypertensive patients was much stronger than that seen in those without hypertension (4 to 7-fold, P < 0.001). Correlation analysis showed that, in contrast to the ACE expression, upregulation of chymase correlated significantly with the increase in BP and the severity of collagen matrix deposition within the glomerulus, tubulointerstitium, and arterial walls (all with P < 0.001). In conclusion, the present study demonstrates that chymase, as an alternative AngII-generating enzyme, is markedly upregulated in the diabetic kidney and may be associated with the development of diabetic/hypertensive nephropathy. In addition, differential expression of ACE and chymase in the diabetic kidney indicates that both ACE and chymase may be of equal importance for AngII-mediated diabetic nephropathy and vascular disease. Results from this study suggest that blockade of both AngII-generating pathways may provide additional beneficial effect on diabetic nephropathy.

A New Self-Penetrating Uniform Net, (8,4) (or 86), Containing Planar Four-Coordinate Nodes

Abstract: Hydrothermal reaction of 3-(3-pyridyl)acrylic acid (pyaraH) with NiCl2 and NaOH results in formation of different polymorphs at different temperatures. alpha-Ni(pyara)2(H2O)2 forms at 180 degrees C, and has a 3D polymeric structure. The topology of the network is that of a self-penetrating, four-coordinate (8,4) network (Schlafli symbol 86). This is the first uniform net to contain only planar four-coordinate nodes, and it is also the first four-coordinate uniform net not to have the Schlafli symbol 66. Tauhis fundamental network topology has been previously unrecognized. Tauhe second polymorph, the beta phase, forms from an analogous reaction at 150 degrees C, and contains 1D chains hydrogen bonded into a 3D network.

A novel, highly electrical conducting, single-component molecular material: [Ag2(ophen)2] (hophen = 1H-[1,10]phenanthrolin-2-one)

Abstract: This communication describes a highly conducting, single-component molecular material [Ag2(ophen)2] (Hophen = 1H-[1,10]phenanthrolin-2-one) based on very strong off-set π−π stacking interactions with an unusually short ring-to-ring distance of ca. 3.15 A between adjacent molecules and silver(I)−π interactions with the Ag···C contact of 3.082 A between adjacent molecules. The title compound, having a room-temperature conductivity of 14 S cm-1, is structurally different from both the known conducting single-component molecular materials of transition-metal complexes with sulfur-containing π-delocalized dithiolene ligands and the known conducting multicomponent organosilver(I) materials.

Soy isoflavones have a favorable effect on bone loss in Chinese postmenopausal women with lower bone mass: a double-blind, randomized, controlled trial.

Abstract: Animal studies have shown that soy isoflavones have an effect in preventing estrogen-related bone loss, but few data are available in humans, especially in the Asian populations. This double-blind, placebo-controlled, randomized trial examines the effects of soy isoflavones on bone loss in postmenopausal Chinese women, aged 48 – 62 yr. Two hundred and three eligible subjects were randomly assigned to three treatment groups with daily doses of placebo (1 g starch; n 67), middose (0.5 g starch, 0.5 g soy extracts, and 40 mg isoflavones; n 68), and high dose (1.0 g soy extracts and 80 mg isoflavones; n 68). All were given 12.5 mmol (500 mg) calcium and 125 IU vitamin D3. Bone mineral density (BMD) and bone mineral content (BMC) of the whole body, spine, and hip were measured using dual energy x-ray absorptiometry at baseline and 1 yr post treatment. Both univariate and multivariate analyses showed that women in the high dose group had mild, but statistically significantly, higher favorable change rate in BMC at the total hip and trochanter (P < 0.05) compared with the placebo and mid-dose groups, even after further adjustments for the potential confounding factors. Further stratified analyses revealed that the positive effects of soy isoflavone supplementation were observed only among women with lower initial baseline BMC (median or less). In conclusion, soy isoflavones have a mild, but significant, independent effect on the maintenance of hip BMC in postmenopausal women with low initial bone mass. (J Clin Endocrinol Metab 88: 4740 – 4747, 2003)

Supramolecular Organisation of Polymeric Coordination Chains into a Three-Dimensional Network with Nanosized Channels that Clathrate Large Organic Molecules

Abstract: Hydrothermal treatment of a mixture of [Zn(MeCO2)2]·H2O, terephthalic acid, and 2,2′-bipyridine resulted in a coordination polymer [Zn(bpy)(tp)](bpy) (1; bpy = 2,2′-bipyridine, H2tp = terephthalic acid) which crystallizes in the monoclinic space group C2/c, Mr = 541.85, a = 15.388(11), b = 21.963(11), c = 7.670(8) A, β = 112.82(2)°, V = 2387(3) A3, Z = 4, Dc = 1.506 g·cm−3. An X-ray single-crystal structural analysis reveals that 1 is a three-dimensional network with nanosized channels constructed from one-dimensional coordination chains via C−H···O hydrogen bonds and aromatic intercalations. TGA and XRPD showed that the porous network of 1 is very stable while the guest 2,2′-bipyridine molecules in the channels are removable. Compound 1 shows a strong ligand-centred emission at room temperature in the solid state. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2003)

Effects of ligand planarity on the interaction of polypyridyl Ru(II) complexes with DNA

Abstract: Two new polypyridyl ligands containing substituent Br at different positions in the phenyl ring, OBIP {OBIP = 2-(2-bromophenyl)imidazo[4,5-f]-1,10-phenanthroline}, PBIP {PBIP = 2-(4-bromophenyl)imidazo[4,5-f]-1,10-phenanthroline} and their Ru(II) complexes, [Ru(dmp)2(OBIP)]2+1 and [Ru(dmp)2(PBIP)]2+2 (dmp = 2,9-dimethyl-1,10-phenanthroline), have been synthesized and characterized. The binding of the two complexes to calf thymus DNA (CT DNA) has been investigated by spectrophotometric methods, viscosity measurements, as well as equilibrium dialysis and circular dichroism spectroscopy. Theoretical calculations for the two complexes were also carried out applying the density functional theory (DFT) method. The structure of complex 1 has been determined by single-crystal X-ray diffraction techniques. The imidazo[4,5-f]-1,10-phenanthroline moiety is not coplanar with the 2-bromophenyl ring, having a dihedral angle of 48.6° in the OBIP ligand. The twisted conformation has been further confirmed by theoretical calculations, in which this dihedral angle is 48.2°. The theoretical calculations also suggest that the PBIP ligand in complex 2 is essentially planar (dihedral angle is 0.4°). The experimental results show that while complex 1 binds to CT DNA via a semi-intercalative mode, complex 2 strongly binds to CT DNA through intercalation. Complex 2 is thus a much better candidate as an enantioselective binder to CT DNA than complex 1. Some experimental regularities or trends have been reasonably explained by the theoretical results. These suggest that the planarity of the intercalated ligand has significant effects on the spectral properties and the DNA-binding behavior of the complexes, and that the DFT method can be used effectively to explain and predict some regularities or trends in the interaction of polypyridyl Ru(II) complexes with DNA.

Hydrothermal Synthesis of Rare Earth (Tb, Y) Hydroxide and Oxide Nanotubes†

Abstract: In this paper, Tb(OH)3 and Y(OH)3 single-crystalline nanotubes with outer diameters of 30–260 nm, inner diameters of 15–120 nm, and lengths of up to several micrometers were synthesized on a large scale by hydrothermal treatment of the corresponding oxides in the presence of alkali. In addition, Tb4O7 and Y2O3 nanotubes can be obtained by calcination of Tb(OH)3 and Y(OH)3 nanotubes at 450 °C. X-ray diffraction (XRD), field-emission scanning electron microscopy, transmission electron microscopy (TEM), electron diffraction (ED), energy-dispersive X-ray spectroscopy (EDS), thermogravimetry, and differential scanning calorimetry (DSC) have been employed to characterize these nanotube materials. The growth mechanism of rare earth hydroxide nanotubes can be explained well by the highly anisotropic crystal structure of rare earth hydroxides. These new types of rare earth compound nanotubes with open ends have uses in a variety of promising applications such as luminescent devices, magnets, catalysts, and other functional materials. Advantages of this method for easily realizing large-scale production include that it is a simple and unique one-pot synthetic process without the need for a catalysts or template, is low cost, has high yield, and the raw materials are readily available. The present study has enlarged the family of nanotubes available, and offers a possible new, general route to one-dimensional single-crystalline nanotubes of other materials.

Correlated noise in a logistic growth model.

Abstract: The logistic differential equation is used to analyze cancer cell population, in the presence of a correlated Gaussian white noise. We study the steady state properties of tumor cell growth and discuss the effects of the correlated noise. It is found that the degree of correlation of the noise can cause tumor cell extinction.

Interaction of macrocyclic copper(II) complexes with calf thymus DNA: effects of the side chains of the ligands on the DNA-binding behaviors

Abstract: Three macrocyclic copper(II) complexes of formula CuL1(ClO4)2 (L1 = 1,4,8,11-tetraazacyclotetradecane), CuL2Cl2 (L2 = 3,10-bis-phenethyl-1,3,5,8,10,12-hexaazacyclotetradecane) and CuL3Cl2 (L3 = 3,10-bis-n-propyl-1,3,5,8,10,12-hexaazacyclotetradecane) have been synthesized and characterized by elemental analysis, infrared spectroscopy and mass spectrometry. X-Ray structural analysis of CuL2(ClO4)2 showed each copper atom to be coordinated to four nitrogen atoms in the macrocycle, which has a square-planar coordination geometry. Absorption and fluorescence spectral studies, circular dichroic spectral and viscometric studies have been carried out to assess the interaction of the three complexes with calf thymus DNA. The results suggest that three complexes can bind to DNA by different binding modes. [CuL1]2+ and [CuL3]2+ can bind to DNA by electrostatic interaction whereas [CuL2]2+ may bind to DNA by intercalation of the aromatic ring into the base pairs of DNA. The functional groups on the side chain of the macrocycle play a key role in deciding the mode and extent of binding of the copper complexes to DNA. The copper complexes exhibit nuclease activities, in which circular plasmid pUC18 DNA is initially converted to nicked DNA.