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1.
《Inorganica chimica acta》1988,145(2):285-288
The stability constants and the heats of formation of vanadyl(IV)—acetate, —glycolate, and —glycine complexes have been determined in aqueous solution by means of potentiometric and calorimetric measurements. In the pH range where the protolitic equilibria of VO2+ is certainly negligible the acetate forms two mononuclear complexes, the glycolate three whereas the glycine reacts in its zwitterionic form. The stabilities of the glycolate complexes are considerably higher than the acetate ones, in spite of its lower basicity, indicating that the complex formation involves the coordination of the hydroxyl group to the metal ion. The enthalpy changes are positive except for the glycolate where a small negative value is found. For all systems the entropy changes are positive and therefore favourable to the complex formation.  相似文献   

2.
Abstract

The formation of complex species in the dimethyltin(IV) and trimethyltin(IV)-carboxymethyl-L-cysteinate (carbocysteinate) systems in NaClaq, at different ionic strengths, and in a multicomponent Na+, K+, Ca2+ ,Mg2+, Cl? and SO42-? medium representative of the seawater major composition, is discussed. Experimental results give evidence for the formation of the following species (L = carbocysteinate): [(CH3)2Sn(L)]0, [(CH3)2Sn(HL)]+, [(CH3)2Sn(OH)(L)]?, [(CH3)2Sn(OH)2(L)]2? in the DMT–CCYS system, and [(CH3)3Sn(HL)]0, [(CH3)3Sn(L)]? and [(CH3)3Sn(OH)(L)]2? in the TMT-CCYS system. The ionic strength dependence of formation constants was taken into account by an extended Debye Hückel type equation and by the SIT (Specific ion Interaction Theory). Measurements were carried out also on the dimethyltin(IV)-glutamate and trimethyltin(IV)-glutamate systems in NaClaq, owing the strict similarity of glutamate and carbocysteinate. Results obtained show the formation of complex species having the same stoichiometry as those formed in the DMT- and TMT-carbocysteinate systems, with very similar stability, confirming that carbocysteinate behaves as a dicarboxylic amino acid without involving the sulfur-bridge potential binding site in metal coordination.  相似文献   

3.
There is mounting evidence demonstrating causative links between hyperglycemia, oxidative stress, and insulin resistance, the core pathophysiological features of type 2 diabetes mellitus. Using a combinational approach, we synthesized a vanadium–antioxidant (i.e., l-ascorbic acid) complex and examined its effect on insulin resistance and oxidative stress. This study was designed to examine whether vanadyl(IV)-ascorbate complex (VOAsc) would reduce oxidative stress, hyperglycemia, and insulin resistance in high-fat high-sucrose diet (HFSD)-induced type 2 diabetes in mice. Male C57BL/6J mice were fed a HFSD for 12 weeks to induce insulin resistance, rendering them diabetic. Diabetic mice were treated with rosiglitazone, sodium l-ascorbate, or VOAsc. At the end of treatment, fasting blood glucose, fasting serum insulin, homeostasis model assessment-insulin resistance index, and serum adipocytokine levels were measured. Serum levels of nitric oxide (NO) parameters were also determined. The liver was isolated and used for determination of malondialdehyde, reduced glutathione, and catalase levels, and superoxide dismutase and glutathione peroxidase activities. VOAsc groups exhibited significant reductions in serum adipocytokine and NO levels, and oxidative stress parameters compared to the corresponding values in the untreated diabetic mice. The results indicated that VOAsc is non-toxic. In conclusion, we identified VOAsc as a potentially effective adjunct therapy for the management of type 2 diabetes.  相似文献   

4.
  • 1.1. The proliferation of RIE-1 rat intestinal epithelial cells was potently but reversibly inhibited by transforming growth factor-β1 (TGF-β1). In early-passage cultures, complete growth arrest was observed when sparse cultures were treated with TGF-β1 (1 ng/ml).
  • 2.2. However, increasing the initial cell culture density resulted in decreased TGF-β1-mediated inhibition of cell proliferation.
  • 3.3. Independent of this population density effect, RIE-1 cells also exhibit a marked phenotypic transition around passage-8 to -10, such that later-passage cells were less responsive to growth inhibition by TGF-β1].
  相似文献   

5.
Mycoplasma contamination is a deleterious event for cell culture laboratories. Plasmocin™ is used to prevent and eradicate mycoplasma infections from cell. In this study, 80 different mammalian cell lines from various sources; human, monkey, mice, hamster and rat were used to study and evaluate plasmocin™ efficiency and compare it to commonly used antibiotics such as BM-cyclin, ciprofloxacin and mycoplasma removal agent (MRA). It was shown that mycoplasma infections were eradicated by plasmocin™, BM-cyclin, ciprofloxacin and MRA in 65%, 66.25%, 20%, and 31.25%, respectively, of infected cell cultures. However, re-infection with mycoplasmas after the period of 4 months occurred in 10–80% of the studied cell lines. Cell cytotoxicity and culture death was observed in 25, 17.5 and 10% of the treated cells, for plasmocin™, BM-cyclin and MRA, respectively. In this study, Plasmocin™ showed strong ability to eradicate mollicutes from our cell lines with minimal percentage of regrowth. However, due to its high cell cytotoxicity it should be used with caution especially when dealing with expensive or hard-to-obtain cell lines. Amongst the antibiotics tested, BM-cyclin was shown to remove mycoplasma with the highest efficiency.  相似文献   

6.
BACKGROUND: Wilms' tumor 1 (WT1) gene expression is seen in a significant number of cases of human neoplasia; however, the mechanism of action remains to be clarified. We hypothesized that WT1 gene is a surrogate marker of proliferation in normal hematopoietic cells and leukemias. While we and others have recognized its value as a tool for the detection of minimal residual disease (MRD), the objective of this study was to confirm our hypothesis regarding normal. METHODS: Samples from healthy donors (n=16) and UC blood (n=9) were cultured in Methocult for 21 days. Colonies were analyzed on days 7, 14 and 21 by RT-PCR for WT1 gene expression. Our positive controls were samples from patients with leukemia (n=91). Negative controls were from normal volunteers without stimulation (n=26). RESULTS: Results showed a statistically significant difference (P<0.0001) between cultured groups, with the highest level of WT1 gene expression in the positive controls and on day 14, when cells are at their maximal proliferation. DISCUSSION: In conclusion, WT1 gene expression in the proliferating colonies was highest on day 14, although less than in leukemia samples, confirming our hypothesis that WT1 gene is a surrogate marker of proliferation, not only in leukemogenesis but also, to a lesser degree, in normal cell proliferation.  相似文献   

7.
The properties and geometry of bone in the mandible play a key role in mandible behaviour during a person’s lifetime, and attention needs to be paid to the influence of bone properties. We analysed the effect of bone geometry, size and bone properties in mandible behaviour, experimenting on cadaveric mandibles and FE models. The study was developed using the geometry of a cadaveric mandible without teeth. Three models of cadaveric condyles were experimentally tested with instrumented with four rosettes, and a condyle reaction of 300 N. Four finite element models were considered to validate the experiments and analyse mandible behaviour. One numeric model was simulated with 10 muscles in a quasi-static condition. The experimental results present different condyle stiffness’s, of 448, 215 and 254 N/mm. The values presented in the rosettes are influenced by bone geometry and bone thickness; maximum value was ?600 με in rosette #4, and the maximum strain difference between mandibles was 111%. The numerical results show that bone density decreases and strain distribution increases in the thinner mandible regions. Nevertheless, the global behaviour of the structure remains similar, but presents different strain magnitudes. The study shows the need to take into account bone characteristics and their evolutions in order to improve implant design and fixation throughout the patient life. The change in bone stiffness promotes a change in maximum strain distribution with same global behaviour.  相似文献   

8.
Possible adsorption configurations and electronic properties, such as charge analysis, density of states, work function and Schottky barrier height of tetracyanoquinodimethane (TCNQ) and tetrathiafulvalene (TTF) on Aluminium (100) surface is studied by using density functional theory methods with local density approximation (LDA), generalised gradient approximation (GGA), PBE and PBE-D2 methods. TCNQ is strongly adsorbed on Al(100) with adsorption energy of ?3.66?eV. The charge is transferred from Al(100) to TCNQ and charge transfer occurs mainly through cyano group of TCNQ. Adsorption on Al(100) surface leads to downshift in energy difference between highest occupied molecular orbital (HOMO) and lowest unoccupied molecular orbital (LUMO) of TCNQ by 2.5?eV as result of hybridisation of p orbital of carbon and nitrogen atoms of TCNQ and p orbital of surface Al atoms. Compared to TCNQ adsorption, TTF adsorption on Al(100) surface is having less adsorption energy and type of interaction is physisorption. The charge transfer from TTF to Al(100) surface leads to decrease in work function of Al by 0.24?eV. The n-type Schottky barrier height of TCNQ/Al(100) and p-type Schottky barrier height of TTF/Al(100) is 0.68eV and 1.97?eV, respectively showing that TCNQ and Al(100) are suitable for organic photovoltaic and electrochemical applications.  相似文献   

9.
Since 1944, we have come a long way using aminoglycosides as antibiotics. Bacteria also have got them selected with hardier resistance mechanisms. Aminoglycosides are aminocyclitols that kill bacteria by inhibiting protein synthesis as they bind to the 16S rRNA and by disrupting the integrity of bacterial cell membrane. Aminoglycoside resistance mechanisms include: (a) the deactivation of aminoglycosides by N-acetylation, adenylylation or O-phosphorylation, (b) the reduction of the intracellular concentration of aminoglycosides by changes in outer membrane permeability, decreased inner membrane transport, active efflux, and drug trapping, (c) the alteration of the 30S ribosomal subunit target by mutation, and (d) methylation of the aminoglycoside binding site. There is an alarming increase in resistance outbreaks in hospital setting. Our review explores the molecular understanding of aminoglycoside action and resistance with an aim to minimize the spread of resistance.  相似文献   

10.
Introduction: Trophoblast homing to maternal spiral arteries is mandatory for successful placentation. Cell-cell adhesion molecules regulate this process and adhesion molecule expression is altered in impaired placentation. We hypothesize that, similar to immune cell recruitment, trophoblast cell adherence and rolling are primarily mediated by adhesion molecules like, cadherins, immunoglobulins, selectins and their partnering ligands. Here, the interdependence of adhesion molecule expression in trophoblastic cell lines of diverse origin was investigated in relation to their interaction with endothelial cell networks on Matrigel® co-cultures and the effect of specific adhesion molecule knockdown analyzed. Methods: Trophoblastic cells were labeled in red and co-cultured with green HUVEC networks on Matrigel®. Association was quantified after collection of fluorescence microscopy pictures using Wimasis® internet platform and software. Expression of adhesion molecules was analyzed by PCR and Western blot, immuno-fluorescence and flow cytometry. The impact of adhesion molecules on trophoblast-endothelial-cell interaction was investigated using siRNA technique. Results: N-cadherin and CD162 were specifically expressed in the trophoblast cell line HTR-8/SVneo, which closely adhere to and actively migrate toward HUVEC networks on Matrigel®. Suppression of N-cadherin led to a significant alteration in trophoblast-endothelial cell interaction. Expression of VE-cadherin in closely interacting trophoblast cells was not confirmed in vitro. Discussion: We identified N-cadherin to mediate specific interaction between HUVEC and the migrating trophoblast cells HTR-8/SVneo in a Matrigel® co-culture model. VE-cadherin contribution could not be confirmed in vitro. Our results support the hypothesis that impaired N-cadherin but not VE-cadherin expression is involved in trophoblast recruitment to the maternal endothelium.  相似文献   

11.

Background

The cytokines TNF (TNFSF2) and IFNγ are important mediators of inflammatory bowel diseases and contribute to enhanced intestinal epithelial permeability by stimulating apoptosis and/or disrupting tight junctions. Apoptosis and tight junctions are also important for epithelial tissue morphogenesis, but the effect of TNF and IFNγ on the process of intestinal epithelial morphogenesis is unknown.

Methods/Principal Findings

We have employed a three-dimensional cell culture system, reproducing in vivo-like multicellular organization of intestinal epithelial cells, to study the effect of TNF on intestinal epithelial morphogenesis and permeability. We show that human intestinal epithelial cells in three-dimensional culture assembled into luminal spheres consisting of a single layer of cells with structural, internal, and planar cell polarity. Exposure of preformed luminal spheres to TNF or IFNγ enhanced paracellular permeability, but via distinctive mechanisms. Thus, while both TNF and IFNγ, albeit in a distinguishable manner, induced the displacement of selected tight junction proteins, only TNF increased paracellular permeability via caspase-driven apoptosis and cell shedding. Infliximab and adalumimab inhibited these effects of TNF. Moreover, we demonstrate that TNF via its stimulatory effect on apoptosis fundamentally alters the process of intestinal epithelial morphogenesis, which contributes to the de novo generation of intestinal epithelial monolayers with increased permeability. Also IFNγ contributes to the de novo formation of monolayers with increased permeability, but in a manner that does not involve apoptosis.

Conclusions

Our study provides an optimized 3D model system for the integrated analysis of (real-time) intestinal epithelial paracellular permeability and morphogenesis, and reveals apoptosis as a pivotal mechanism underlying the enhanced permeability and altered morphogenesis in response to TNF, but not IFNγ.  相似文献   

12.
Summary An AcMNPV recombinant (Ac-gal-luc) carrying theβ-galactosidase and luciferase genes under the control of the p10 and polyhedrin promoters, respectively, was used to study expression in nine insect cell lines. All AcMNPV-permissive cell lines expressed both reporter genes with the coleopteran cell line,Anthonomus grandis (AGE), producing the highest concentrations ofβ-galactosidase (5.0×106 pg/ml) and luciferase (2.67×103 pg/ml). Both enzymes were detected as early as 12 h postinoculation in lysate samples of the AGE cell line.Helicoverpa armigera (HA), a nonpermissive cell line, expressedβ-galactosidase at 72 h postinoculation at a concentration of 3.5×103 pg/ml. However, expression of luciferase was not detected. Expression of luciferase andβ-galactosidase was also not detected in the nonpermissiveHelicoverpa zea (HZ) cell line.  相似文献   

13.
Emergence of resistance to chemotherapy and radiotherapy is a major obstacle for the successful treatment of MM (multiple myeloma). Prednisone, vincristine and melphalan are commonly used chemotherapeutic agents for the treatment of MM. In the current study, we examined the presence of possible cross-resistance between these drugs and gamma (γ) radiation. Prednisone, vincristine and melphalan resistant RPMI-8226 and U-266 MM cells were generated by stepwise increasing concentrations of the drugs. The sensitive and resistant cells were exposed to 200- and 800 cGy γ radiation, and proliferation was examined by XTT {2,3-bis(2-methoxy-4-nitro-5-sulfophenyl)-5-[(phenylamino)carbonyl]-2H-tetrazolium hydroxide} assay. The results showed that Prednisone- and melphalan-resistant RPMI-8226 cells were also cross-resistant to 200 and 800 cGy γ radiation application, while vincristine-resistant cells did not show resistance. On the other hand, Prednisone-, vincristine- and melphalan-resistant U-266 cells showed cross-resistance to 200- and 800 cGy γ radiation application. These results demonstrated that MM cells resistant to anticancer agents respond to radiation in different levels. These findings may be important in the clinical applications of radiation therapy in the treatment of vincristine resistant MM.  相似文献   

14.
The series of new zirconium(IV) and hafnium(IV) phthalocyanines with various β-dicarbonyl ligands were prepared via direct interaction between di(chloro)zirconium(IV) or hafnium(IV) phthalocyanines and free β-diketones and also with 4-benzoyl-3-methyl-1-phenyl-2-pyrazolin-5-one. The structure of the obtained bis(β-dicarbonilato) zirconium(IV) and hafnium(IV) phthalocyanines was studied by two dimension 1H NMR spectroscopy (COSY, NOESY, ROESY). Absorption and fluorescence spectroscopic studies have been investigated in various solvents. Analyzed compounds of concentration range below 10?5 mol/dm3 do not aggregate in the organic solvents. Fluorescence quantum yields (ΦF) and natural life times (τ) of zirconium phthalocyanine complexes have been calculated in toluene, DMSO and THF.  相似文献   

15.
Type IV collagen, the major component of basement membrane, consists primarily of ·1(IV) and ·2(IV) chains. Recently, other types of collagen IV chains, i.e. ·3(IV), ·4(IV), ·5(IV) and ·6(IV) chains, have been identified by protein chemistry and molecular cloning. We have examined the diversity of the assembly of ·(IV) chains of the basement membrane surrounding tumour nests of basal cell carcinomas, in tissues from 11 patients, by immunohistochemical analysis using specific monoclonal antibodies to six ·(IV) chain. The immunostaining profile of each chain differed with respect to the histological subtypes of basal cell carcinoma. In the morphea-like subtype, which was more invasive, ·1(IV) and ·2(IV) chains were discontinuously stained, and ·5(IV) and ·6(IV) chains were entirely absent. However, in the superficial subtype, which was non-aggressive, ·1(IV), ·2(IV), ·5(IV) and ·6(IV) chains were well stained compared with the other subtypes of basal cell carcinoma. In addition, in the solid subtype, which showed slow growth and ulceration, ·1(IV) and ·2(IV) chains were continuously stained, and ·5(IV) and ·6(IV) chains were discontinuous or absent. The assembly of ·5(IV) and ·6(IV) chains into the basement membrane was inhibited in the solid and morphea subtypes of BCC. This differential expression of type IV collagen chains seems to be associated with the invasive potential of basal cell carcinoma This revised version was published online in November 2006 with corrections to the Cover Date.  相似文献   

16.
(1) The content of DNA, RNA and of proteins of Brachionus plicatilis was estimated and the distribution of RNA and of proteins of different homogenate fractions characterised. (2) Ribosomes were isolated from Brachionus plicatilis homogenates and were characterised by gradient centrifugation. (3) Unlike the RNA content, the yield of ribosomes from different homogenate fractions is strongly dependent on the concentration of Mg2+-ions in the buffers. Likewise resuspension of ribosomes is more effective in Mg2+- (or Ca2+-) free buffers. (4) Dissociation of ribosomes was brought about by centrifugation of ribosomes in gradients containing less than 4 mM Mg2+. In this case, beside the peaks of subunits, a peak in the region of 80 S remained which vanished only under conditions destroying ribosomal material altogether. (5) Proteins were isolated from ribosomal subunits and from undissociated ribosomes and were characterised by two-dimensional gel electrophoresis techniques. Patterns of 51 spots were regularly obtained from large subunits and patterns of 41 spots from small subunits. The undissociated ribosomes showed 83 spots, most of which could be attributed to the large or the small subunit. The ribosomal proteins have molecular masses of between 11000 and 56000 Da, while the molecular mass of the total protein content of Brachionus ribosomes was estimated to be 1.8 ±0.5) ×106 Da.  相似文献   

17.
Chordoma is a rare tumor of the bone derived from remnants of the notochord with pronounced chemoresistance. A common feature of the notochord and chordoma cells is distinct vacuolization. Recently, the notochord vacuole was described as a lysosome-related organelle. Since lysosomes are considered as mediators of drug resistance in cancer, we were interested whether they may also play a role in chemoresistance of chordoma. We characterized the lysosomal compartment in chordoma cell lines by cytochemistry, electron microscopy (ELMI) and mutational analysis of genes essential for the physiology of lysosomes. Furthermore, we tested for the first time the cytotoxicity of chloroquine, which targets lysosomes, on chordoma. Cytochemical stainings clearly demonstrated a huge mass of lysosomes in chordoma cell lines with perinuclear accumulation. Also vacuoles in chordoma cells were positive for the lysosomal marker LAMP1 but showed no acidic pH. Genetic analysis detected no apparent mutation associated with known lysosomal pathologies suggesting that vacuolization and the huge lysosomal mass of chordoma cell lines is rather a relict of the notochord than a result of transformation. ELMI investigation of chordoma cells confirmed the presence of large vacuoles, lysosomes and autophagosomes with heterogeneous ultrastructure embedded in glycogen. Interestingly, chordoma cells seem to mobilize cellular glycogen stores via autophagy. Our first preclinical data suggested no therapeutically benefit of chloroquine for chordoma. Even though, chordoma cells are crammed with lysosomes which are according to their discoverer de Duve “cellular suicide bags”. Destabilizing these “suicide bags” might be a promising strategy for the treatment of chordoma.  相似文献   

18.
The mechanism of antimalarial action of the ruthenium-chloroquine complex [RuCl(2)(CQ)](2) (1), previously shown by us to be active in vitro against CQ-resistant strains of Plasmodium falciparum and in vivo against P. berghei, has been investigated. The complex is rapidly hydrolyzed in aqueous solution to [RuCl(OH(2))(3)(CQ)](2)[Cl](2), which is probably the active species. This compound binds to hematin in solution and inhibits aggregation to beta-hematin at pH approximately 5 to a slightly lower extent than chloroquine diphosphate; more importantly, the heme aggregation inhibition activity of complex 1 is significantly higher than that of CQ when measured at the interface of n-octanol-aqueous acetate buffer mixtures under acidic conditions modeling the food vacuole of the parasite. Partition coefficient measurements confirmed that complex 1 is considerably more lipophilic than CQ in n-octanol-water mixtures at pH approximately 5. This suggests that the principal target of complex 1 is the heme aggregation process, which has recently been reported to be fast and spontaneous at or near water-lipid interfaces. The enhanced antimalarial activity of complex 1 is thus probably due to a higher effective concentration of the drug at or near the interface compared with that of CQ, which accumulates strongly in the aqueous regions of the vacuole under those conditions. Furthermore, the activity of complex 1 against CQ-resistant strains of P. falciparum is probably related to its greater lipophilicity, in line with previous reports indicating a lowered ability of the mutated transmembrane transporter PfCRT to promote the efflux of highly lipophilic drugs. The metal complex also interacts with DNA by intercalation, to a comparable extent and in a similar manner to uncomplexed CQ and therefore DNA binding does not appear to be an important part of the mechanism of antimalarial action in this case.  相似文献   

19.
4-Hydroxynonenal (HNE) is the most studied end product of the lipoperoxidation process, by virtue of its relevant biological activity. The antiproliferative and proapoptotic effects of HNE have been widely demonstrated in a great variety of tumor cell types in vitro. Thus, it might represent a promising new molecule in anticancer therapy strategies. However, the extreme reactivity of this aldehyde, as well as its insolubility in water, a limiting factor for drug bioavailability, and its rapid degradation by specific enzymes represent major obstacles to its possible in vivo application. Various strategies can used to overcome these problems. One of the most attractive strategies is the use of nanovehicles, because loading drugs into nanosized structures enhances their stability and solubility, thus improving their bioavailability and their antitumoral effectiveness. Several natural or synthetic polymers have been used to synthesize nanosized structures and, among them, β-cyclodextrin (βCD) polymers are playing a very important role in drug formulation by virtue of the ability of βCD to form inclusion compounds with a wide range of solid and liquid molecules by molecular complexation. Moreover, several βCD derivatives have been designed to improve their physicochemical properties and inclusion capacities. Here we report that the inclusion complex of HNE with a derivative of βCD, the βCD–poly(4-acryloylmorpholine) conjugate (PACM-βCD), enhances the aldehyde stability. Moreover, the inclusion of HNE in PACM-βCD potentiates its antitumor effects in several tumor cell lines and in a more complex system, such as a human reconstructed skin carrying melanoma tumor cells.  相似文献   

20.
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