Determination of uremic solutes in biological fluids of chronic kidney disease patients by HPLC assay

During chronic kidney disease (CKD), solutes called uremic solutes, accumulate in blood and tissues of patients. We developed an HPLC method for the simultaneous determination of several uremic solutes of clinical interest in biological fluids: phenol (Pol), indole-3-acetic acid (3-IAA), p-cresol (p-C), indoxyl sulfate (3-INDS) and p-cresol sulfate (p-CS). These solutes were separated by ion-pairing HPLC using an isocratic flow and quantified with a fluorescence detection. The mean serum concentrations of 3-IAA, 3-INDS and p-CS were 2.12, 1.03 and 13.03 μM respectively in healthy subjects, 3.21, 17.45 and 73.47 μM in non hemodialyzed stage 3-5 CKD patients and 5.9, 81.04 and 120.54 μM in hemodialyzed patients (stage 5D). We found no Pol and no p-C in any population. The limits of quantification for 3-IAA, 3-INDS, and p-CS were 0.83, 0.72, and 3.2 μM respectively. The within-day CVs were between 1.23 and 3.12% for 3-IAA, 0.98 and 2% for 3-INDS, and 1.25 and 3.01% for p-CS. The between-day CVs were between 1.78 and 5.48% for 3-IAA, 1.45 and 4.54% for 3-INDS, and 1.19 and 6.36% for p-CS. This HPLC method permits the simultaneous and quick quantification of several uremic solutes for daily analysis of large numbers of samples.     

Sequence Conservation in the Prediction of Catalytic Sites

Predicting catalytic sites of a given enzyme is an important open problem of Bioinformatics. Recently, many machine learning-based methods have been developed which have the advantage that they can account for many sequential or structural features. We found that although many kinds of features are incorporated, protein sequence conservation is the main part of information they used and should play an important role in the future. So we tested several conservation features in their ability to predict catalytic sites by using the Support Vector Machine classifier. Our results suggest that position specific scoring matrix performs better than other features and incorporating conservation information of sequentially adjacent sites is more effective than that of structurally adjacent ones. Moreover, although conservation information is effective in predicting catalytic sites, it is a difficult problem to optimize the combination of conservation features and other ones.     

Synthesis of Partially Graphitic Ordered Mesoporous Carbons with High Surface Areas

Graphitic carbons with ordered mesostructure and high surface areas (of great interest in applications such as energy storage) have been synthesized by a direct triblock‐copolymer‐templating method. Pluronic F127 is used as a structure‐directing agent, with a low‐molecular‐weight phenolic resol as a carbon source, ferric oxide as a catalyst, and silica as an additive. Inorganic oxides can be completely eliminated from the carbon. Small‐angle XRD and N₂ sorption analysis show that the resultant carbon materials possess an ordered 2D hexagonal mesostructure, uniform bimodal mesopores (about 1.5 and 6 nm), high surface area (～1300 m²/g), and large pore volumes (～1.50 cm³/g) after low‐temperature pyrolysis (900 °C). All surface areas come from mesopores. Wide‐angle XRD patterns demonstrate that the presence of the ferric oxide catalyst and the silica additive lead to a marked enhancement of graphitic ordering in the framework. Raman spectra provide evidence of the increased content of graphitic sp² carbon structures. Transmission electron microscopy images confirm that numerous domains in the ordered mesostructures are composed of characteristic graphitic carbon nanostructures. The evolution of the graphitic structure is dependent on the temperature and the concentrations of the silica additive, and ferric oxide catalyst. Electrochemical measurements performed on this graphitic mesoporous carbon when used as an electrode material for an electrochemical double layer capacitor shows rectangular‐shaped cyclic voltammetry curves over a wide range of scan rates, even up to 200 mV/s, with a large capacitance of 155 F/g in KOH electrolyte. This method can be widely applied to the synthesis of graphitized carbon nanostructures.     

Affinity enhancement bivalent morpholino for pretargeting: initial evidence by surface plasmon resonance

Pretargeting with bivalent effectors capable of bridging antitumor antibodies has been reported to provide superior results by affinity enhancement. Morpholinos (MORFs) and other DNA analogues used for pretargeting are ideally suited as bivalent effectors since they are easily synthesized and the distance between binding regions, likely to be a determinant of binding, may be adjusted simply by lengthening the chain. The goal of this investigation was to synthesize a bivalent MORF and to determine by surface plasmon resonance (SPR) whether the bivalent MORF exhibited bimolecular binding and whether the MORFs showed improved in vitro hybridization affinity in its bivalent form compared to its monovalent form. An 18 mer amino-derivitized MORF was made bivalent by dimerizing with disuccinimidyl suberate (DSS) in 1-methyl-2-pyrrolidinone (NMP) with N,N-diisopropylethylamine (DIEA) followed by purification by ion exchange chromatography. The in vitro hybridization affinity of bivalent compared to monovalent MORF was then measured by SPR. For these measurements, the complementary biotinylated cDNA was immobilized at coating densities that provided an average spacing of 20-100 angstroms and used to investigate the influence of this spacing on binding of the bivalent MORF with its binding regions separated by 25 A. The yield of bivalent MORF was as high as 45%, and the structure was confirmed by MALDI-TOF mass spectroscopy. When the sensograms obtained by SPR were analyzed using different binding models, the evidence was consistent with bimolecular binding of the bivalent MORF. The dissociation rate constant of the bivalent compared to monovalent MORF was more than 10-fold lower at 2.14 compared to 0.27 x 10(-5) (1/s) (p < 0.05), and since the association rate constants were similar at 8.53 and 5.64 x 10(5) (1/M.s) (p = 0.08), the equilibrium constant for hybridization to the immobilized cDNA of the bivalent compared to the monovalent MORF was almost 20-fold higher at 3.99 compared to 0.21 x 10(10) (1/M) (p < 0.05). In addition, qualitative evidence for bivalent binding of the bivalent MORF was apparent in the lower concentrations necessary to saturate the cDNA. Finally, the stoichiometry interpretation of the binding data provided estimates of the fraction of bivalent MORF binding bimolecularly. Under one set of conditions, this value was 20%. In conclusion, a bivalent MORF was easily synthesized by dimerization of a monovalent MORF. A lower dissociation rate constant and higher equilibrium constant was measured by SPR for the bivalent compared to monovalent MORF in their binding to an immobilized cDNA. These results show that bimolecular binding was occurring in the case of the bivalent MORF and suggest that bivalency may be superior to monovalency in MORF pretargeting applications.     

Inhibition by [corrected] ursolic acid of [corrected] calcium-induced mitochondrial permeability transition and release of two proapoptotic proteins

The possible inhibition by [corrected] ursolic acid (UA) of [corrected] mitochondrial permeability transition (MPT) in mouse liver was investigated to identify the mechanisms underlying the hepatoprotective effect of UA. The effect of UA on liver MPT induced by Ca2+ was assessed by measuring changes in mitochondrial volume, mitochondrial membrane potential (MMP), release of matrix Ca2+, and transfer of cytochrome c (Cyt c) and apoptosis-inducing factor (AIF) from the intermembrane space to the cytoplasm. The results showed that obvious mitochondrial swelling, loss of MMP, and release of matrix Ca2+ occurred after the addition of 50 microM Ca2+. However, preincubation with 20, 50 or 100 microg ml(-1) UA significantly blocked the above changes. Addition of 100 microg ml(-1) UA inhibited on mitochondrial swelling by 73.2% after 5 min, while the MMP dissipating and Ca2+ releasing were, respectively, suppressed by 59.3% and 54.1% after 3 min. In addition, Western blot analysis showed Cyt c and AIF transferred from mitochondrial pellet to the supernatant after the addition of 50 microM Ca2+, but the process was significantly inhibited by various concentrations of UA. The results suggest that the mechanisms underlying the hepatoprotection of UA may be related to its direct inhibitory action on MPT.     

Heat shock protein 90 indirectly regulates ERK activity by affecting Raf protein metabolism

Extracellular signal-regulated protein kinase (ERK) has been implicated in the pathogenesis of several nerve system diseases. As more and more kinases have been discovered to be the client proteins of the molecular chaperone Hsp90, the use of Hsp90 inhibitors to reduce abnormal kinase activity is a new treatment strategy for nerve system diseases. This study investigated the regulation of the ERK pathway by Hsp90. We showed that Hsp90 inhibitors reduce ERK phosphorylation without affecting the total ERK protein level. Further investigation showed that Raf, the UPstream kinase in the Ras-Raf-MEK-ERK pathway, forms a complex with Hsp90 and Hsp70. Treating cells with Hsp90 inhibitors facilitates Raf degradation,thereby down-regulating the activity of ERK.     

Neuroregulatory events follow adaptive immune-mediated elimination of HIV-1-infected macrophages: studies in a murine model of viral encephalitis

HIV-1-specific cellular immunity serves to eliminate infected cells and disease. However, how this process specifically affects the CNS is poorly understood. To mirror the regulatory events that occur in human brain after HIV-1 infection, a murine model of viral encephalitis was used to study relationships, over time, among lymphocyte-mediated infected cell elimination, innate immune responses, and neuropathology. Nonobese diabetic SCID mice were reconstituted with human PBL and a focal encephalitis induced by intracranial injection of autologous HIV-1-infected, monocyte-derived macrophages (MDM). On days 7, 14, and 21 after MDM injection into the basal ganglia, the numbers of human lymphocytes and mouse monocytes, virus-infected MDM, glial (astrocyte and microglial) responses, cytokines, inducible NO (iNOS), neurotrophic factors, and neuronal Ags were determined in brain by immunohistochemistry, real-time PCR, and Western blot assays. Microglia activation, astrocytosis, proinflammatory cytokines, and iNOS expression accompanied the loss of neuronal Ags. This followed entry of human lymphocytes and mouse monocytes into the brain on days 7 and 14. Elimination of virus-infected human MDM, expression of IL-10, neurotropins, and a down-regulation of iNOS coincided with brain tissue restoration. Our results demonstrate that the degree of tissue damage and repair parallels the presence of infected macrophages and effectors of innate and adaptive immunity. This murine model of HIV-1 encephalitis can be useful in elucidating the role played by innate and adaptive immunity in disease progression and resolution.