Tunnel barrier enhanced voltage signal generated by magnetization precession of a single ferromagnetic layer

We report the electrical detection of magnetization dynamics in an Al/AlOx/Ni80Fe20/Cu tunnel junction, where a Ni80Fe20 ferromagnetic layer is brought into precession under ferromagnetic resonance conditions. The dc voltage generated across the junction by the precessing ferromagnet is enhanced about an order of magnitude compared to the voltage signal observed when the contacts in this type of multilayered structure are Ohmic. We discuss the relation of this phenomenon to magnetic spin pumping and speculate on other possible underlying mechanisms responsible for the enhanced electrical signal.

Extraction and protein component analysis of venom from the dissected venom glands of Latrodectus tredecimguttatus

Black widow spiders (genus Latrodectus) have attracted increasing attention due to frequently reported human injuries caused by them and the potential applications of biologically active components in their venoms. Although a number of studies have described the biological properties and structures of several venomous proteins such as latrotoxins, a comprehensive analysis of protein component of the venom from the spider is not available. We used combinative proteomic strategies to assess the protein components of the crude venom collected from Latrodectus tredecimguttatus by extracting the dissected venom glands. The experiments demonstrated that the crude venom of L. tredecimguttatus has a high abundance of acidic proteins with molecular masses greater than 15 kDa, and the content of proteins and peptides of below 15 kDa is low. 86 unique proteins were identified, part of which were contaminations of cellular components during the extraction, determined in comparison with venom obtained by electrostimulation. Except for members of latrotoxin family that were commonly considered as the primary toxic components of the venom, several other special enzymes and proteins were detected such as protease, phosphatase, lysozyme, inhibitory protein, and so on. These protein components, particularly the proteases, were speculated to play important roles in the action of L. tredecimguttatus venom.

Proteomic analysis of low-abundant integral plasma membrane proteins based on gels

To characterize low-copy integral membrane proteins and offer some methods for human liver proteome projects, we fractionated highly purified rat liver plasma membrane (PM). PM was purified through two sucrose density gradient centrifugations, and treated with 0.1 M Na(2)CO(3), chloroform/methanol and Triton X-100. Proteins were separated by electrophoresis and submitted to mass spectrometry analysis. Four hundred and fifty-seven non-redundant membrane proteins were identified, of which 23% (105) were integral membrane proteins with one or more transmembrane domains. One hundred and fifty-three (33.5%) had no location annotation and 68 were unknown-function proteins. The proteins from different fractions were complementory. A database search for all identified proteins revealed that 53 proteins were involved in the cell communication pathway. More interestingly, more than 50% of the proteins had a protein abundance index concentration of less than 0.1 mol/l, and 12% proteins a concentration 100 times less than that of arginase 1 and actin.

Design, synthesis and in vitro and in vivo antitumor activities of novel β-carboline derivatives

To further our SAR study on the chemistry and antitumor activity/neurotoxicity of beta-carboline alkaloids, several series of beta-carboline derivatives with various substituents were designed and synthesized from the starting material l-tryptophan on the basis of harmine chemical structure. Cytotoxic activities of these compounds were investigated in vitro. The results showed that some beta-carboline derivatives had significant cytotoxic activities against human tumor cell lines. Among all the synthesized beta-carboline derivatives, the compounds 27, 28 and 32, having a benzyl substituent at both position-2 and 9, respectively, were found to be the most potent compounds with IC50 value lower than 50 microM against all human tumor cell lines examined. Acute toxicities and antitumor activities of the selected beta-carboline derivatives in mice were also evaluated. The results demonstrated that a benzyl substituent at position-2 increased the antitumor activity as well as acute toxicity significantly. However an (ethoxycarbonyl)amino substituent at position-3 reduced the acute toxicity as well as antitumor activity remarkedly. These data suggested that (1) the antitumor potencies of beta-carboline derivatives were enhanced by the introduction of benzyl substituent into the position-2; (2) the acute toxicity of beta-carboline derivatives reduced dramatically by the introduction of an appropriate substituent into the position-3 and 9; (3) the beta-carboline structure might be an important basis for the design and synthesis of new antitumor drugs with significant antitumor activity and low toxicity.

Performance of a combined eco-system of ponds and constructed wetlands for wastewater reclamation and reuse

An on-site study on the operational performance of a combined eco-system of ponds and SF constructed wetland for municipal wastewater treatment and reclamation/reuse in Donging City, Shandong, China was carried out from January 2001 through October 2003. The removal efficiencies for various main parameters were: TSS 84.8 +/- 7.3%, BOD5 87.2 +/- 5.3%, CODCr 70.2 +/- 18.6%, TP 52.3 +/- 23.1%, and NH(3)-N 54.8 +/- 23.9% with effluent concentration of TSS 9.12 +/- 5.12 mg/l, BOD5 6.44 +/- 4.58 mg/l, CODCr, 42.8 +/- 6.7 mg/l, TP 0.94 +/- 0.27 mg/l and NH(3)-N 7.95 +/- 2.36 mg/l. In addition, the removal efficiencies for faecal coliforms and total bacteria were > 99.97% and > 99.998% respectively, which well meet Chinese National standards for effluent quality of municipal wastewater treatment plants. The composition of TSS was closely related to CODCr and BOD5 variations, and nitrification-denitrification is the major mechanism of nitrogen removal both in ponds and in wetlands. In addition, sedimentation also played an important role in the removal of TSS, nitrogen, phosphorus and BOD5. The removal efficiencies of various parameters, the number of species and biomass of biological community in the system increased gradually with the ecological maturation.

Towards nanomedicine with a supramolecular approach: a review

A review dedicated mainly to the results obtained by the authors on the use of cyclodextrin (CD) derivatives on protein (enzyme) stabilization through covalent and non-covalent interactions (host-guest supramolecular interactions) is presented here. This latter procedure served to introduce a new method for enzyme immobilization on metallic surfaces that can be used to prepare biosensors and therapeutic nanodevices. The surfaces of gold (and silver) electrodes and nanoparticles were modified with sulphur-containing cyclodextrin derivatives. The protein (enzyme) was then supramolecularly immobilized on the modified surface when one or more of its bulky hydrophobic moieties was included into the CD cavity. The protein can also be modified with a typical CD guest, such as adamantane, to achieve a more stable immobilization. Different examples are presented, such as a biosensor based on monolayers of adamantane-modified cytochrome c and a bienzymatic nanodevice comprising gold nanoparticles stabilized with CD associated to catalase and superoxide dismutase modified with complementary host-guest residues. The possibilities of this new approach for the development of biosensors and therapeutic nanodevices are analyzed.

Pathogenesis and pathology of delayed xenograft rejection in pig-to-rhesus monkey cardiac transplantation

It has been recognized that delayed xenograft rejection (DXR) is the major barrier to the acceptance of xenotransplantation after overcoming hyperacute rejection.

OBJECTIVES

This study sought to investigate the pathogenesis and pathology of delayed xenograft rejection following pig-to-rhesus monkey heart xenotransplantation.

METHODS

Heterotopic xenogeneic heart transplants in the abdominal cavity were performed using piglet donors to four monkey recipients. Complete complement depletion was achieved in the recipients with repetitive doses of high-activity cobra venom factor (Y-CVF). The recipients were immunosuppressed with a combination of cyclosporine, cyclophosphamide, and steroids. Sera were analyzed for C3 and C4 levels and complement activity and anti-pig endothelial xenoantibody. The grafts were examined histopathologically and immunohistochemically for C3, C4;C5b-9, IgM, IgG, tumor necrosis factor-alpha (TNF-alpha), intercellular adhesion molecule-1(ICAM-1), CD57(NK cells), CD68 (macrophages), CD4, and CD8.

RESULTS

Xenografts survived 8, 10, 13, and 13 days respectively, all developing DXR. Venous thrombosis was the outstanding feature within DXR xenografts, complicated by interstitial edema, local hemorrhage, myocardial necrosis, and mild to moderate cellular infiltration. The serum C3 levels and complement activity decreased to almost 0 from the day of transplantation due to treatment with Y-CVF. The C4 level began to decrease 2 to 4 days before the cardiac xenografts lost their function. Anti-pig endothelial xenoantibody also decreased after transplantation, slightly increasing during DXR. All rejected xenografts showed C3, C4, C5b-9, IgG, and IgM deposits to various degrees. Large numbers of macrophages (50% of total leukocytes) infiltrated the entire xenograft with a few natural killer cells (8% to 10%), as well as some CD4+ T cells (15%) and CD8+ T cells (25%). Upregulation of ICAM-1 on graft endothelial cells and TNF-alpha in the interstitium were also demonstrated in the rejected heart.

CONCLUSION

Both humoral and cell-mediated immunologic reactions may play important roles in the pathogenesis of DXR. Besides C3, C4, C5b-9, IgM, and IgG destroying the xenograft, NK cells, macrophages, and CD4+ and CD8+ T cells may further aggravate the development of DXR.

Differential expression of NMDA and AMPA receptor subunits in DARPP-32-containing neurons of the cerebral cortex, hippocampus and neostriatum of rats

Dopamine and cyclic adenosine 3',5'-monophosphate-regulated phosphoprotein, 32 kDa (DARPP-32) is a key element of dopamine/D1/DARPP-32/protein phosphatase-1 (PP-1) signaling cascades of mammalian brain. We are interested in the expression patterns of N-methyl-D-aspartate (NMDA) and alpha-amino-3-hydroxy-5-methyl-4-isoxazolepropionate (AMPA) receptors in DARPP-32-containing neurons, which may constitute morphological basis for interaction between dopamine and ionotropic glutamate receptors in dopaminoceptive cells. Double immunofluorescence was performed to visualize neurons showing coexpression of DARPP-32 with NMDA or AMPA receptor subunits (i.e., NR1, NR2a/b, glutamate receptor subunit 1 [GluR1], GluR2/3, and GluR4) in the forebrains of rats. Distribution of DARPP-32-positive neurons completely or partially overlapped with that of NMDA receptor- or AMPA receptor-immunoreactive ones in the frontal and parietal cortex, hippocampus and neostriatum, and neurons double-labeled with DARPP-32/NR1, DARPP-32/NR2a/b, DARPP-32/GluR1, DARPP-32/GluR2/3, or DARPP-32/GluR4 immunoreactivity were numerously observed. Semiquantification analysis indicated that most of DARPP-32-containing neurons (86-98%) expressed NR1, NR2a/b and GluR2/3, while less of them (14-90%) expressed GluR1 and GluR4. Although high rates (90-98%) of DARPP-32-positive cells expressed NMDA receptors in all regions above, variant percentages of them expressing AMPA receptor subunits were observed among the cortex (54-90%), hippocampus (59-97%) and neostriatum (14-97%). The study presents differential expression patterns of NMDA and AMPA receptors in DARPP-32-postive neurons in these forebrain regions. Taken together with previous reports, the present data suggest that interaction between dopamine and glutamate receptors may occur in the dopaminoceptive neurons with distinct receptor compositions and may be involved in modulating neuronal properties and excitotoxicity in mammalian forebrain.

The striatal GABA-ergic neurons expressing substance P receptors in the basal ganglia of mice

By using a double immunofluorescence, we have examined the distribution of striatal GABAergic neurons that expressed substance P receptor (SPR) in the basal ganglia of adult C57 mice. The distribution of GABA-immunoreactive neurons completely or partially overlapped with that of SPR-immunoreactive neurons in the striatum (i.e. the caudate-putamen), globus pallidus, ventral pallidum, and nucleus accumbens. Neurons showing both GABA- and SPR-immunoreactivities were, however, predominantly found in the caudate-putamen, and most of them were characterized by their large-sized aspiny neuronal profile. Semi-quantification indicated that only about 13% of the total GABA-immunoreactive neurons (including large and medium-sized) displayed SPR-immunoreactivity, and these double-labeled neurons constituted about 31% of the total SPR-immunoreactive cells in the striatum. Neurons double-labeled with GABA- and SPR-immunoreactivities were hardly detected in other aforementioned regions of the basal ganglia. In addition, double immunofluorescence also showed co-localization of SPR- with glutamic acid decarboxylase-immunoreactivity, but not with parvalbumin-immunoreactivity, in the striatal neurons. Taken together with previous reports, the present study has suggested that a sub-population of striatal GABA-ergic neurons, most possibly GABA-ergic interneurons, may also receive direct physiological modulation by tachykinins through SPR in the basal ganglia of mammals.

Nestin-containing cells express glial fibrillary acidic protein in the proliferative regions of central nervous system of postnatal developing and adult mice

We are interested in the expression patterns of nestin, an embryonic intermediate filament that represent a neural precursor marker, in the mammalian central nervous system. With an immunohistochemical approach, distribution of nestin-containing cells and their colocalization with glial fibrillary acidic protein (GFAP) or neuronal nuclear specific protein (NeuN) were studied in adult and postnatal days 2-30 (P2-30) mice. Nestin-immunoreactivity was predominately distributed in certain proliferative regions, such as cerebral cortex, hippocampus, hypothalamus, subfornical organ, cerebellar cortex, area postrema, midline raphe glial structures, as well as ependymal and subependymal zones of the brain and spinal cord. The majority of nestin-immunoreactive cells, characterized by astroglial profiles of multiple and radial processes, showed a partial overlapping distribution with that of GFAP-immunoreactive astroglial cells. Double immunofluorescence confirmed that about 77% of these nestin-immunoreactive cells exhibited GFAP-immunoreactivity, indicating that a large percentage of nestin-expressing cells may have committed to astroglial cells. In developing mice, down-regulation of nestin expression was observed between P7 and P14. Although co-expression of nestin and NeuN occurred in cortical neurons of P2-7 mice, nestin-containing cells showing NeuN-immunoreactivity disappeared in CNS in older animals. Our results reveal the distribution pattern of nestin-containing neural precursors in the postnatal CNS and provide evidence on their differentiation fate to neurons and astrocytes, suggesting that nestin-containing glial cells may play an important role in remodeling and repairing in the postnatal and adult central nervous system.

New method to measure minisatellite variant repeat variation in population genetic studies

The classical analysis of minisatellite variant repeat (MVR) variation using modular structures is limited by the lack of knowledge of the mutational process involved in the evolution of most of the minisatellites. In this study a new method to measure MVR variation and to calculate genetic distances using MVR codes is proposed. The method is based on the statistical similarity of MVR patterns and considers the complete variability of the minisatellite, enabling meaningful comparisons of closely related populations. As an example, the method has been applied to analyze variation in MSY1 (DYF155S1) in five sets of data from European and North African populations.

Solvothermal Syntheses and Characterizations of Two Isomorphous One-Dimensional Chain Complexes Constructed by Orotic Acid

Solvothermal reactions of M(OAc)2 (M = Ni, Co) with orotic acid (2,6-dioxo-1,2,3,6-tetrahydropyrimidine-4-carboxylic acid, H3L) in H2O/MeOH (1 : 1) gave rise to two new isomorphous polymeric complexes, [M(HL)(H2O)3]n [M = Ni, (4); Co, (5)], with one-dimensional chain structures. Both complexes crystallize in the orthorhombic space group P212121, with a 7.7438(7), b 7.7610(7), c 14.6528(12) �, Z 4 for (4), and a 7.7005(3), b 7.8725(3), c 14.6997(10) �, Z 4 for (5). X-Ray diffraction analysis shows that the metal ion is coordinated by nitrogen and oxygen atoms of an orotate ligand (HL2–) and water molecules in a distorted octahedral geometry. The hydrogen-bond interactions between chains leads to the formation of three-dimensional network structures.

Purification and functional characterization of a histone H3-lysine 4-specific methyltransferase

Methylation of histone H3 at lysine 9 by SUV39H1 and subsequent recruitment of the heterochromatin protein HP1 has recently been linked to gene silencing. In addition to lysine 9, histone H3 methylation also occurs at lysines 4, 27, and 36. Here, we report the purification, molecular identification, and functional characterization of an H3-lysine 4-specific methyltransferase (H3-K4-HMTase), SET7. We demonstrate that SET7 methylates H3-K4 in vitro and in vivo. In addition, we found that methylation of H3-K4 and H3-K9 inhibit each other. Furthermore, H3-K4 and H3-K9 methylation by SET7 and SUV39H1, respectively, have differential effects on subsequent histone acetylation by p300. Thus, our study provides a molecular explanation to the differential effects of H3-K4 and H3-K9 methylation on transcription.

Inhibitory PAS domain protein is a negative regulator of hypoxia-inducible gene expression

Alteration of gene expression is a crucial component of adaptive responses to hypoxia. These responses are mediated by hypoxia-inducible transcription factors (HIFs). Here we describe an inhibitory PAS (Per/Arnt/Sim) domain protein, IPAS, which is a basic helix-loop-helix (bHLH)/PAS protein structurally related to HIFs. IPAS contains no endogenous transactivation function but demonstrates dominant negative regulation of HIF-mediated control of gene expression. Ectopic expression of IPAS in hepatoma cells selectively impairs induction of genes involved in adaptation to a hypoxic environment, notably the vascular endothelial growth factor (VEGF) gene, and results in retarded tumour growth and tumour vascular density in vivo. In mice, IPAS was predominantly expressed in Purkinje cells of the cerebellum and in corneal epithelium of the eye. Expression of IPAS in the cornea correlates with low levels of expression of the VEGF gene under hypoxic conditions. Application of an IPAS antisense oligonucleotide to the mouse cornea induced angiogenesis under normal oxygen conditions, and demonstrated hypoxia-dependent induction of VEGF gene expression in hypoxic corneal cells. These results indicate a previously unknown mechanism for negative regulation of angiogenesis and maintenance of an avascular phenotype.

Preparations, structures, and magnetic properties of a series of novel copper(II)-lanthanide(III) coordination polymers via hydrothermal reaction

The hydrothermal reaction of Ln2O3 (Ln = Er, Gd, and Sm), pyridine-2,5-dicarboxylic acid (H2pydc), and Cu(II) reagents (CuO, Cu(OAc)2-2H2O, or CuCl2-2H2O) with a mole ratio of 1:2:4 resulted in the formation of six polymeric Cu(II)-Ln(III) complexes, [(Ln2Cu3(pydc)6(H2O)12)-4H2O]n (Ln = Er (1); Ln = Gd (2)), [(Ln4Cu2(pydc)8(H2O)12)-4H2O]n (Ln = Sm (3); Ln = Gd (4); Ln = Er (5)), and [(Gd2Cu2(pydc)4(H2O)8)-Cu(pydc)2-12H2O]n (6). 1 and 2 are isomorphous and crystallize in triclinic space group Ponebar. Compounds 3-5 are isomorphous and crystallize in monoclinic space group P2(1)/c. Compound 6 crystallizes in triclinic space group Ponebar. Complexes 1 and 2 have one-dimensional zigzag chain structures and compounds 3-5 display three-dimensional wavelike polymeric structures, while 6 has an infinite sandwich-type structure. The different structures of the complexes are induced by the different forms of Cu(II) reagents; the reactions of Cu(OAc)2-2H2O yield high Cu/Ln ratio products 1, 2, and 6, while the reactions of CuO or CuCl2-2H2O/2,2'-bipyridine results in low Cu/Ln ratio compounds 3-5. Temperature-dependent magnetic susceptibilities for 2, 4, and 5 were studied, and the thermal stabilities of complexes 2 and 4 were examined.

The metastasis-associated Mts1(S100A4) protein could act as an angiogenic factor

The involvement of Mts1(S100A4), a small Ca(2+)-binding protein in tumor progression and metastasis had been demonstrated. However, the mechanism by which mts1(S100A4) promoted metastasis had not been identified. Here we demonstrated that Mts1(S100A4) had significant stimulatory effect on the angiogenesis. We detected high incidence of hemangiomas--benign tumors of vascular origin in aged transgenic mice ubiquitously expressing the mts1(S100A4) gene. Furthermore, the serum level of the Mts1(S100A4) protein increased with ageing. Tumors developed in Mts1-transgenic mice revealed an enhanced vascular density. We showed that an oligomeric, but not a dimeric form of the Mts1(S100A4) protein was capable of enhancing the endothelial cell motility in vitro and stimulate the corneal neovascularization in vivo. An oligomeric fraction of the protein was detected in the conditioned media as well as in human serum. The data obtained allowed us to conclude that mts1(S100A4) might induce tumor progression via stimulation of angiogenesis.