Biomedical subjects

Ming Zheng

Publications and source records attributed to Ming Zheng.

45 records · Page 3Linked to original sources

PubMed2003

Phosphonooxymethyl prodrugs of the broad spectrum antifungal azole, ravuconazole: synthesis and biological properties.

Synthesis of phosphonooxymethyl derivatives of ravuconazole, 2 (BMS-379224) and 3 (BMS-315801) and their biological evaluation as potential water-soluble prodrugs of ravuconazole are described. The phosphonooxymethyl ether analogue 2 (BMS-379224) and N-phosphonooxymethyl triazolium salt 3 (BMS-315801) were both prepared from ravuconazole (1) and bis-tert-butyl chloromethylphosphate, but under two different conditions. Both derivatives were highly soluble in water and converted to the parent in alkaline phosphatase, and also in vivo (rat). However, BMS-315801 was found to be less stable than BMS-379224 in water at neutral pH. BMS-379224 (2) has proved to be one of the most promising prodrugs of ravuconazole that we tested, and it is currently in clinical evaluation as an intravenous formulation of the broad spectrum antifungal azole, ravuconazole.

Animals↗

PubMed2003

Zoledronic acid delays the onset of skeletal-related events and progression of skeletal disease in patients with advanced renal cell carcinoma.

BACKGROUND: The objective of this study was to assess the efficacy and safety of zoledronic acid in patients with bone metastases secondary to renal cell carcinoma (RCC). METHODS: A retrospective subset analysis of patients with RCC enrolled in a multicenter, randomized, placebo-controlled study of zoledronic acid was performed. Patients were randomized to receive zoledronic acid (4 or 8 mg as a 15-minute infusion) or placebo with concomitant antineoplastic therapy every 3 weeks for 9 months. The primary efficacy analysis was the proportion of patients with one or more skeletal-related events (SREs), which were defined as pathologic fracture, spinal cord compression, radiation therapy, or surgery to bone. Secondary analyses included time to first SRE, skeletal morbidity rate (events per year), disease progression, and multiple event analysis. RESULTS: In this subset of 74 patients with RCC, zoledronic acid (4 mg) was found to significantly reduce the proportion of patients with an SRE (37% vs. 74% for placebo; P = 0.015). Similarly, zoledronic acid significantly reduced the mean skeletal morbidity rate (2.68 vs. 3.38 for placebo; P = 0.014) and extended the time to the first event (median not reached vs. 72 days for placebo; P = 0.006). A multiple event analysis demonstrated that the risk of developing an SRE was reduced by 61% compared with placebo (hazard ratio of 0.394; P = 0.008). The median time to progression of bone lesions was significantly longer for patients who were treated with zoledronic acid (P = 0.014 vs. placebo). Zoledronic acid appeared to be well tolerated; the most common adverse events in all treatment groups included bone pain, nausea, anemia, and emesis. CONCLUSIONS: Zoledronic acid (4 mg as a 15-minute infusion) demonstrated significant clinical benefit in patients with bone metastases from RCC, suggesting that further investigation of zoledronic acid in this patient population is warranted.

Aged↗

PubMed2003

Zoledronic acid versus placebo in the treatment of skeletal metastases in patients with lung cancer and other solid tumors: a phase III, double-blind, randomized trial--the Zoledronic Acid Lung Cancer and Other Solid Tumors Study Group.

PURPOSE: To assess the efficacy and safety of zoledronic acid in patients with bone metastases secondary to solid tumors other than breast or prostate cancer. PATIENTS AND METHODS: Patients were randomly assigned to receive zoledronic acid (4 or 8 mg) or placebo every 3 weeks for 9 months, with concomitant antineoplastic therapy. The 8-mg dose was reduced to 4 mg (8/4-mg group). The primary efficacy analysis was proportion of patients with at least one skeletal-related event (SRE), defined as pathologic fracture, spinal cord compression, radiation therapy to bone, and surgery to bone. Secondary analyses (time to first SRE, skeletal morbidity rate, and multiple event analysis) counted hypercalcemia as an SRE. RESULTS: Among 773 patients with bone metastases from lung cancer or other solid tumors, the proportion with an SRE was reduced in both zoledronic acid groups compared with the placebo group (38% for 4 mg and 35% for 8/4 mg zoledronic acid v 44% for the placebo group; P =.127 and P =.023 for 4-mg and 8/4-mg groups, respectively). Additionally, 4 mg zoledronic acid significantly increased time to first event (median, 230 v 163 days for placebo; P =.023), an important end point in this poor-prognosis population, and significantly reduced the risk of developing skeletal events by multiple event analysis (hazard ratio = 0.732; P =.017). Zoledronic acid was well tolerated; the most common adverse events in all treatment groups included bone pain, nausea, anemia, and vomiting. CONCLUSION: Zoledronic acid (4 mg infused over 15 minutes) is the first bisphosphonate to reduce skeletal complications in patients with bone metastases from solid tumors other than breast and prostate cancer.

Bone Neoplasms↗

PubMed2003

Ethylene glycol monolayer protected nanoparticles for eliminating nonspecific binding with biological molecules.

The usefulness of the hybrid materials of nanoparticles and biological molecules in many occasions depends on how well one can achieve a rational design based on specific binding and programmable assembly. Nonspecific binding between nanoparticles and biomolecules is one of the major barriers for achieving its utilities in a biological system. In this paper, we demonstrate a new approach to eliminate nonspecific interactions between nanoparticles and proteins by synthesizing ethylene glycol protected gold nanoparticles. We discovered that with the water content optimized in the range of 9-18% in the reaction mixture, di-, tri-, and tetra(ethylene glycol) protected gold nanoparticles Au-S-EGn (n = 2, 3, and 4) could be directly synthesized. These gold nanoparticles that are bonded with a uniform monolayer with defined length varying from 0.8 to 1.6 nm (from molecular modeling) have great stability in aqueous solutions with a high concentration of electrolyte and organic solutions. Using ion-exchange chromatography and gel electrophoresis, we demonstrated that these Au-S-EGn (n = 2, 3, or 4) nanoparticles have complete resistance to protein nonspecific interactions. These types of nanoparticles provide a fundamental starting material for designing hybrid materials composed of metallic nanoparticles and biomolecules.

Biocompatible Materials↗

PubMed2003

Identification of a broad-spectrum azasordarin with improved pharmacokinetic properties.

The synthesis and antifungal activity of 5'- and 5'-6'-substituted azasordarin derivatives are described. Modification of the 5'-position led to the discovery of the spirocyclopentyl analogue 7g, which is the first azasordarin to register single-digit MIC values versus Aspergillus spp. Further investigation identified the 5'-i-Pr derivative 7b, which displays superior pharmacokinetic properties compared to other azasordarins.

Administration, Oral↗

PubMed2003

Interleukin-6 family of cytokines mediates isoproterenol-induced delayed STAT3 activation in mouse heart.

This study was aimed to determine whether beta-adrenergic receptor (beta-AR) stimulated by isoproterenol (ISO) activates signal transducers and activators of transcription (STAT) in mouse heart and, if so, to examine the underlying mechanism. We found that treatment of adult male mice by ISO (15 mg/kg body weight, intraperitoneal) caused a delayed STAT3 activation (at 60-120 min), which was fully abolished by beta-AR antagonist, propranolol. ISO-induced phosphorylation of STAT3 was markedly enhanced by phosphodiesterase inhibitor amrinone, indicating that cAMP is critically involved in beta-AR-mediated STAT3 activation. In addition, beta-AR stimulation significantly increased gene expression of interleukin-6 (IL-6) family of cytokines (IL-6, leukemia inhibitory factor, ciliary neurotrophic factor, and cardiotrophin-1). IL-6 protein levels in serum and mouse myocardium were also significantly increased in response to ISO treatment. In cultured cardiac fibroblasts, IL-6 level was enhanced significantly after ISO (10-6 mol/liter) stimulation for 2 h and then peaked at 12 h, whereas the response of IL-6 in cultured cardiomyocytes to ISO stimulation was not significant, suggesting that ISO-induced increase in IL-6 is primarily from cardiac fibroblasts rather than cardiomyocytes. Most importantly, IL-6 could activate STAT3 in a time-dependent manner in cultured cardiomyocytes, and inhibition of IL-6 level by anti-IL-6-neutralizing antibody clearly attenuated ISO-induced phosphorylation of STAT3 in myocardium. Taken together, these results indicate that beta-AR stimulation leads to a delayed STAT3 activation via an IL-6 family of cytokine-mediated pathway and that cardiac fibroblasts, but not cardiomyocytes, is probably the predominant source of IL-6 in response to ISO stimulation in mouse myocardium.

Adrenergic beta-Agonists↗

PubMed2003

DNA-assisted dispersion and separation of carbon nanotubes.

Carbon nanotubes are man-made one-dimensional carbon crystals with different diameters and chiralities. Owing to their superb mechanical and electrical properties, many potential applications have been proposed for them. However, polydispersity and poor solubility in both aqueous and non-aqueous solution impose a considerable challenge for their separation and assembly, which is required for many applications. Here we report our finding of DNA-assisted dispersion and separation of carbon nanotubes. Bundled single-walled carbon nanotubes are effectively dispersed in water by their sonication in the presence of single-stranded DNA (ssDNA). Optical absorption and fluorescence spectroscopy and atomic force microscopy measurements provide evidence for individually dispersed carbon nanotubes. Molecular modelling suggests that ssDNA can bind to carbon nanotubes through pi-stacking, resulting in helical wrapping to the surface. The binding free energy of ssDNA to carbon nanotubes rivals that of two nanotubes for each other. We also demonstrate that DNA-coated carbon nanotubes can be separated into fractions with different electronic structures by ion-exchange chromatography. This finding links one of the central molecules in biology to a technologically very important nanomaterial, and opens the door to carbon-nanotube-based applications in biotechnology.

Biotechnology↗

PubMed2002

p38 Mitogen-activated protein kinase mediates a negative inotropic effect in cardiac myocytes.

p38 Mitogen-activated protein kinase (MAPK) is one of the most ancient signaling molecules and is involved in multiple cellular processes, including cell proliferation, cell growth, and cell death. In the heart, enhanced activation of p38 MAPK is associated with ischemia/reperfusion injury and the onset of heart failure. In the present study, we investigated the function of p38 MAPK in regulating cardiac contractility and its underlying mechanisms. In cultured adult rat cardiomyocytes, activation of p38 MAPK by adenoviral gene transfer of an activated mutant of its upstream kinase, MKK3bE, led to a significant reduction in baseline contractility, compared with uninfected cells or those infected with a control adenoviral vector (Adv-beta-galactosidase). The inhibitory effect of MKK3bE on contractility was largely prevented by coexpressing a dominant-negative mutant of p38 MAPK or treating cells with a p38 MAPK inhibitor, SB203580. Conversely, inhibition of endogenous p38 MAPK activity by SB203580 rapidly and reversibly enhanced cell contractility in a dose-dependent manner, without altering L-type Ca(2+) currents or Ca(2+)(i) transients. MKK3bE-induced p38 activation had no significant effect on pH(i), whereas SB203580 had a minor effect to elevate pH(i). Furthermore, activation of p38 MAPK was unable to increase troponin I phosphorylation. Thus, we conclude that the negative inotropic effect of p38 MAPK is mediated by decreasing myofilament response to Ca(2+), rather than by altering Ca(2+)(i) homeostasis and that the reduced myofilament Ca(2+) sensitivity is unlikely attributable to troponin I phosphorylation or alterations in pH(i). These findings reveal a novel function of p38 MAPK and shed a new light on our understanding of the coincidence of p38 MAPK activation and the onset of heart failure.

Actin Cytoskeleton↗

PubMed1996

Orbital Configuration of the Valence Electrons, Ligand Field Symmetry, and Manganese Oxidation States of the Photosynthetic Water Oxidizing Complex: Analysis of the S(2) State Multiline EPR Signals.

A theoretical framework is presented for analysis of all three "multiline" EPR spectra (MLS) arising from the tetramanganese (Mn(4)) cluster in the S(2) oxidation state of the photosynthetic water oxidizing complex (WOC). Accurate simulations are presented which include anisotropy of the g and (four) (55)Mn hyperfine tensors, chosen according to a database of (55)Mn(III) and (55)Mn(IV) hyperfine tensors obtained previously using unbiased least-squares spectral fitting routines. In view of the large (30%) anisotropy common to Mn(III) hyperfine tensors in all complexes, previous MLS simulations which have assumed isotropic hyperfine constants have required physically unrealistic parameters. A simple model is found which offers good simulations of both the native "19-21-line" MLS and the "26-line" NH(3)-bound form of the MLS. Both a dimer-of-dimers and distorted-trigonal magnetic models are examined to describe the symmetry of the Heisenberg exchange interactions within the Mn(4) cluster and thus define the initial electronic basis states of the cluster. The effect of rhombic symmetry distortions is explicitly considered. Both magnetic models correspond to one of several possible structural models for the Mn(4) cluster proposed independently from Mn EXAFS studies. Simulated MLS were constructed for each of the eight (or seven) doublet states of the Mn(4) cluster in the WOC for the two viable oxidation models (3Mn(III)-1Mn(IV) or 3Mn(IV)-1Mn(III)), and using a wide range of axial Mn hyperfine tensors, with either coaxial or orthogonal tensor alignments. We find accurate simulations using the 3Mn(III)-1Mn(IV) oxidation model. In the dimer-of-dimers coupling model, the spin state conversion between two doublet states |S(12),S(34),S(T)|(7)/(2),4,(1)/(2)> and |(7)/(2),3,(1)/(2)> is found to explain the large (25%) contraction in the hyperfine splitting observed upon conversion from the native MLS to the NH(3)-bound MLS. Stabilization of this excited state as the new ground state is caused by change in the intermanganese exchange coupling, without appreciable change in the intrinsic hyperfine tensors. The lack of good simulations of the Ca(2+)-depleted MLS suggests that Ca(2+)-depletion changes both Mn ligation and intermanganese exchange coupling. The 3Mn(IV)-1Mn(III) oxidation model is disfavored because only approximate simulations could be found for the native MLS and no agreement with the NH(3)-bound MLS was obtained. The scalar part of the hyperfine tensors for both Mn(III) and Mn(IV) ions were found to approximate (+/-5%) the values for the dimanganese(III,IV) catalase enzyme, suggesting similar overall ligand types. However, the large (30%) anisotropic part of the Mn(III) hyperfine interaction is opposite in sign to that found in all tetragonally extended six-coordinate Mn(III) ions (i.e., the usual Jahn-Teller splitting). The distribution of spin density from the high-spin d(4) electron configuration of each Mn(III) ion corresponds to a flattened (oblate) ellipsoid. This electronic distribution is favored in five-coordinate ligand fields having trigonally compressed bipyramidal geometry, but it could also arise, in principle, in strained six-coordinate ligand fields having tetragonally compressed geometry, i.e. [Mn(2)(&mgr;-O)](4+) (reverse Jahn-Teller distortion). The resulting valence electronic configurations are described as e'(2)e"(2) and (d(pi))(3)(d(x)()()2(-)(y)()()2)(1), respectively, in contrast to the (d(pi))(3)(d(z)()()2)(1) configuration common to unstrained six-coordinate tetragonally-extended Mn(III) ions, such as found in the [Mn(2)(&mgr;-O)(2)](3+) core in several synthetic dimers and catalase. Both of the former geometries predict strongly oxidizing Mn(III) ions, thereby suggesting a structural basis for the oxidative reactivity of the Mn(4) cluster in the WOC. The magnetic model needed to explain the MLS is not readily reconciled with the simplest structural and electronic models deduced from EXAFS studies of the WOC.

Journal Article↗