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Biomedical subjects

Ming Zheng

Publications and source records attributed to Ming Zheng.

At least 37 records · Page 2Linked to original sources
PubMed2004

Identification and synthesis of norhydromorphone, and determination of antinociceptive activities in the rat formalin test.

The main objective of this paper is to report the identification and synthesis of norhydromorphone, a novel metabolite of hydromorphone, and its antinociceptive activities when tested in the formalin test as compared to other known analgesics. In addition, we are reporting for the first time the lack of antinociceptive activities of hydromorphone-3-glucuronide, dihydromorphine-3-glucuronide and dihydroisomorphine-3-glucuronide in the rat formalin test. Norhydromorphone was isolated and identified as a metabolite of hydromorphone in a cancer patient's urine. An authentic standard of norhydromorphone was synthesized. The identity of norhydromorphone in the urine sample was confirmed by comparing the LC retention time and MS ion fragmentation with the synthetic standard using a liquid chromatographic-mass spectrometric-mass spectrometric (LC-MS-MS) assay. Norhydromorphone was found to be a minor metabolite of hydromorphone in the urine. Additionally, the antinociceptive activities of norhydromorphone, hydromorphone, morphine, dihydromorphine, dihydroisomorphine, hydromorphone-3-glucuronide, dihydromorphine-3-glucuronide and dihydroisomorphine-3-glucuronide were determined in the rat formalin test following intraperitoneal (i.p.) administration. Only limited antinociception was observed and no significant increase in antinociception was detected at the three doses tested. The increased polarity of norhydromorphone as compared to hydromorphone due to the primary piperidine nitrogen may make it less favorable to cross the blood-brain-barrier (BBB), which may be partly responsible. In addition, lower intrinsic antinociceptive activity, which remains to be determined, could also contribute to the low antinociception. Our results also show that hydromorphone was five times as potent as morphine in the formalin test, while dihydromorphine and dihydroisomorphine were equipotent to and 36% as potent as morphine, respectively. Hydromorphone-3-glucuronide, dihydromorphine-3-glucuronide and dihydroisomorphine-3-glucuronide did not exhibit any antinociceptive effect at the doses tested. The results further underscore the importance of a free C3-OH to the analgesic effect of morphine alkaloids.

Analgesics, Opioid↗
PubMed2004

Phosphatidylinositol 3-kinase offsets cAMP-mediated positive inotropic effect via inhibiting Ca2+ influx in cardiomyocytes.

Phosphoinositide 3-kinase (PI3K) has been implicated in beta2-adrenergic receptor (beta2-AR)/G(i)-mediated compartmentation of the concurrent G(s)-cAMP signaling, negating beta2-AR-induced phospholamban phosphorylation and the positive inotropic and lusitropic responses in cardiomyocytes. However, it is unclear whether PI3K crosstalks with the beta1-AR signal transduction, and even more generally, with the cAMP/PKA pathway. In this study, we show that selective beta1-AR stimulation markedly increases PI3K activity in adult rat cardiomyocytes. Inhibition of PI3K by LY294002 significantly enhances beta1-AR-induced increases in L-type Ca2+ currents, intracellular Ca2+ transients, and myocyte contractility, without altering the receptor-mediated phosphorylation of phospholamban. The LY294002 potentiating effects are completely prevented by betaARK-ct, a peptide inhibitor of beta-adrenergic receptor kinase-1 (betaARK1) as well as G(betagamma) signaling, but not by disrupting G(i) function with pertussis toxin. Moreover, forskolin, an adenylyl cyclase activator, also elevates PI3K activity and inhibition of PI3K enhances forskolin-induced contractile response in a betaARK-ct sensitive manner. In contrast, PI3K inhibition affects neither the basal contractility nor high extracellular Ca2+-induced increase in myocyte contraction. These results suggest that beta1-AR stimulation activates PI3K via a PKA-dependent mechanism, and that G(betagamma) and the subsequent activation of betaARK1 are critically involved in the PKA-induced PI3K signaling which, in turn, negates cAMP-induced positive inotropic effect via inhibiting sarcolemmal Ca2+ influx and the subsequent increase in intracellular Ca2+ transients, without altering the receptor-mediated phospholamban phosphorylation, in intact cardiomyocytes.

Androstadienes↗
PubMed2004

Intracellular acidosis-activated p38 MAPK signaling and its essential role in cardiomyocyte hypoxic injury.

Activation of p38 mitogen-activated protein kinase (MAPK) plays a central role in cellular responses to a multitude of stress signals. In the heart, enhanced p38 MAPK signaling has been implicated in cardiac hypoxic and ischemic injury. However, the mechanism underlying hypoxia-induced p38 MAPK activation remains elusive. We investigated p38 MAPK activation during hypoxia in adult rat cardiomyocytes. Here, we reported that hypoxia leads to concurrent intracellular acidosis and activation of p38 MAPK and that the hypoxia-induced p38 MAPK signaling can be fully abolished by neutralizing intracellular pH, whereas intracellular acidosis (intracellular pH<7.0) per se overtly augments activation of p38 MAPK but not ERK1/2 and JNK. Furthermore, inhibition of p38 MAPK protects myocytes against hypoxic cell death, suggesting that acidosis-evoked p38 MAPK signaling plays an important role in hypoxic cell injury and cell death. These results demonstrate, for the first time, that intracellular acidosis constitutes a necessary and sufficient link responsible for hypoxia-activated p38 MAPK signaling and the subsequent hypoxic cardiomyocyte injury and death.

Acidosis↗
PubMed2004

Nanoparticles comprising a mixed monolayer for specific bindings with biomolecules.

This work presents a strategy of using mixed monolayer protected nanoparticles for specific interactions with target biological molecules. The mixed monolayer is composed of a shielding component and a capture component. The shielding component utilizes ethylene glycol oligomers to prevent nonspecific binding with biomolecules. The capture component is chosen to specifically interact with the target of interest, such as a protein molecule. Such a concept was demonstrated by two synthetic systems. The first one is gold nanoparticles protected by a mixed monolayer of tri(ethylene glycol) thiol (EG(3)-SH) and tiopronin (Tp), which was prepared by a one-step synthesis. Surface chemical composition studies using (1)H NMR spectroscopy revealed that the reactivity of EG(3)-SH is 3 times as high as that of Tp in the nanoparticle formation. Gel electrophoresis analysis identified a critical ratio of (EG(3)-S-)/Tp on the nanoparticle surface above which no nonspecific binding occurred. By further derivatizing Tp into a biotin group, we synthesized Au(-S-EG(3))(n)/Tp-biotin particles that bind specifically to streptavidin with negligible nonspecific binding. The second system is gold nanoparticles protected by a mixed monolayer of EG(3)-SH and glutathione (GSH). By controlling the feeding ratio of EG(3)-SH and GSH, we made Au(-S-EG(3))(n)/GSH particles that bind specifically to gultathione-S-transferase (GST) with negligible nonspecific binding.

Biotin↗
PubMed2004

Skeletal complications in patients with bone metastases from renal cell carcinoma and therapeutic benefits of zoledronic acid.

Bone metastases in patients with renal cell carcinoma are associated with a high risk of skeletal complications. Therefore, a subset analysis of a larger clinical trial was performed to determine the efficacy of zoledronic acid in renal cell carcinoma patients. Patients with bone metastases from solid tumors other than breast or prostate cancer (n=773) were randomized to receive zoledronic acid or placebo via 15-minute infusion every 3 weeks for 9 months. Patients were monitored for skeletal-related events, which were defined as pathological fracture, spinal cord compression, radiotherapy, or surgery to bone. Among the subset of 74 patients with renal cell carcinoma, 46 patients were treated with 4 mg of zoledronic acid or placebo. Significantly fewer patients treated with 4 mg zoledronic acid had a skeletal-related event (37% versus 74% for placebo, P=0.015), and zoledronic acid significantly prolonged the time to first skeletal-related event (median not reached at 9 months versus 72 days for placebo; P=0.006). Zoledronic acid significantly reduced the annual incidence of skeletal-related events by approximately 21% (mean 2.68 versus 3.38 events per year for placebo, P=0.014) and significantly reduced the risk of developing a skeletal-related event by 61% compared with placebo (risk ratio=0.394, P=0.008) by multiple event analysis. Median time to progression of bone lesions was also significantly extended with zoledronic acid treatment (P=0.014). Zoledronic acid is the first bisphosphonate to significantly reduce skeletal morbidity and significantly prolong time to bone lesion progression in patients with bone metastases from renal cell carcinoma.

Bone Diseases↗
PubMed2004

Long-term efficacy and safety of zoledronic acid in the treatment of skeletal metastases in patients with nonsmall cell lung carcinoma and other solid tumors: a randomized, Phase III, double-blind, placebo-controlled trial.

BACKGROUND: The authors previously reported the efficacy of a dose of 4 mg of zoledronic acid in reducing skeletal complications in patients with bone metastases secondary to lung carcinoma and other solid tumors (except carcinomas of the breast and prostate). In the current study, they update these results and report the long-term efficacy and safety of 21 months of treatment with zoledronic acid in a randomized, placebo-controlled trial. METHODS: A total of 773 patients were randomized to receive zoledronic acid (4 mg or 8 mg) or placebo via a 15-minute infusion every 3 weeks for 21 months. The 8-mg dose later was reduced to 4 mg (8/4-mg group). The primary efficacy endpoint was the percentage of patients at 21 months with >/= 1 skeletal-related event (SRE) (pathologic fracture, spinal cord compression, radiation therapy to bone, or surgery to bone). Secondary analyses (time to first SRE, annual incidence of SREs, and multiple-event analysis) included hypercalcemia of malignancy. RESULTS: Fewer patients treated with zoledronic acid developed at least 1 SRE at 21 months compared with patients treated with placebo (39% of those treated at the 4-mg dose [P =0.127] and 36% of those treated at the 8/4-mg dose [P = 0.023], compared with 46% of those treated with placebo). Furthermore, 4 mg of zoledronic acid significantly delayed the median time to first SRE (236 days with 4 mg vs. 155 days with placebo; P = 0.009) and significantly reduced the annual incidence of SREs (1.74 per year with the 4-mg dose vs. 2.71 per year with placebo; P = 0.012). Moreover, the 4-mg dose of zoledronic acid was found to reduce the risk of developing a skeletal event by 31% (hazard ratio of 0.693; P = 0.003). Zoledronic acid was found to be well tolerated with long-term use; the most commonly reported adverse events in all treatment groups included bone pain and the transient, acute-phase reactions of nausea, anemia, and emesis. CONCLUSIONS: To the authors' knowledge, zoledronic acid is the first bisphosphonate to demonstrate long-term safety and efficacy in this patient population.

Antineoplastic Agents↗
PubMed2004

Long-term efficacy of zoledronic acid for the prevention of skeletal complications in patients with metastatic hormone-refractory prostate cancer.

In a placebo-controlled randomized clinical trial, zoledronic acid (4 mg via a 15-minute infusion every 3 weeks for 15 months) reduced the incidence of skeletal-related events (SREs) in men with hormone-refractory metastatic prostate cancer. Among 122 patients who completed a total of 24 months on study, fewer patients in the 4-mg zoledronic acid group than in the placebo group had at least one SRE (38% versus 49%, difference = -11.0%, 95% confidence interval [CI] = -20.2% to -1.3%; P =.028), and the annual incidence of SREs was 0.77 for the 4-mg zoledronic acid group versus 1.47 for the placebo group (P=.005). The median time to the first SRE was 488 days for the 4-mg zoledronic acid group versus 321 days for the placebo group (P =.009). Compared with placebo, 4 mg of zoledronic acid reduced the ongoing risk of SREs by 36% (risk ratio = 0.64, 95% CI = 0.485 to 0.845; P =.002). Patients in the 4-mg zoledronic acid group had a lower incidence of SREs than did patients in the placebo group, regardless of whether they had an SRE prior to entry in the study. Long-term treatment with 4 mg of zoledronic acid is safe and provides sustained clinical benefits for men with metastatic hormone-refractory prostate cancer.

Aged↗
PubMed2004

Ethylene glycol monolayer protected nanoparticles: synthesis, characterization, and interactions with biological molecules.

The usefulness of the hybrid materials of nanoparticles and biological molecules on 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 their utilities in a biological system. In this paper, we demonstrate a new approach to eliminate nonspecific interactions between nanoparticles and biological molecules by shielding the nanoparticle with a monolayer of ethylene glycol. A direct synthesis of di-, tri-, and tetra(ethylene glycol)-protected gold nanoparticles (Au-S-EGn, n = 2, 3, and 4) was achieved under the condition that the water content was optimized in the range of 9-18% in the reaction mixture. With controlled ratio of [HAuCl4]/[EGn-SH] at 2, the synthesized particles have an average diameter of 3.5 nm and a surface plasma resonance band around 510 nm. Their surface structures were confirmed by 1H NMR spectra. These gold nanoparticles are bonded with a uniform monolayer with defined lengths of 0.8, 1.2, and 1.6 nm for Au-S-EG2, Au-S-EG3, and Au-S-EG4, respectively. They have great stabilities in aqueous solutions with a high concentration of electrolytes as well as in organic solvents. Thermogravimetric analysis revealed that the ethylene glycol monolayer coating is ca. 14% of the total nanoparticle weight. Biological binding tests by using ion-exchange chromatography and gel electrophoresis demonstrated that these Au-S-EGn (n = 2, 3, or 4) nanoparticles are free of any nonspecific bindings with various proteins, DNA, and RNA. These types of nanoparticles provide a fundamental starting material for designing hybrid materials composed of metallic nanoparticles and biomolecules.

Biocompatible Materials↗
PubMed2004

Distinct beta-adrenergic receptor subtype signaling in the heart and their pathophysiological relevance.

In the heart, stimulation of beta-adrenergic receptors (betaAR) serves as the most powerful means to increase cardiac contractility and relaxation in response to stress or a "fight-or-flight" situation. However, sustained beta-adrenergic stimulation promotes pathological cardiac remodeling such as myocyte hypertrophy, apoptosis and necrosis, thus contributing to the pathogenesis of chronic heart failure. Over the past decade, compelling evidence has demonstrated that coexisting cardiac betaAR subtypes, mainly beta(1)AR and beta (2)AR, activate markedly different signaling cascades. As a result, acute beta(1)AR stimulation activates the G(s) -adenylyl cyclase-cAMP-PKA signaling that can broadcast throughout the cell, whereas beta(2)AR-evoked cAMP signaling is spatially and functionally compartmentalized, due to concurrent G(i) activation. Chronic stimulation of beta(1)AR and beta(2)AR elicits opposing effects on the fate of cardiomyocytes: beta(1)AR induces hypertrophy and apoptosis; but beta(2)AR promotes cell survival. The cardiac protective effect of beta(2)AR is mediated by a signaling pathway sequentially involving G(i), G(betagamma), PI3K and Akt. Unexpectedly, beta(1)AR-induced myocyte hypertrophy and apoptosis are independent of the classic cAMP/PKA pathway, but require activation of Ca(2+)/calmodulin-dependent kinase II (CaMK II). The outcomes of cardiac-specific transgenic overexpression of either beta AR subtype in mice have reinforced the fundamentally different functional roles of these betaAR subtypes in governing cardiac remodeling and performance. These new insights regarding betaAR subtype stimulation not only provide clues as to cellular and molecular mechanisms underlying the beneficial effects of beta AR blockers in patients with chronic heart failure, but also delineate rationale for combining selective beta(1)AR blockade with moderate beta(2)AR activation as a potential novel therapy for the treatment of chronic heart failure.

Adenylyl Cyclases↗
PubMed2004

Prominent roles of the NorR and Fur regulators in the Escherichia coli transcriptional response to reactive nitrogen species.

We examined the genomewide transcriptional responses of Escherichia coli treated with nitrosylated glutathione or the nitric oxide (NO)-generator acidified sodium nitrite (NaNO(2)) during aerobic growth. These assays showed that NorR, a homolog of NO-responsive transcription factors in Ralstonia eutrophus, and Fur, the global repressor of ferric ion uptake, are major regulators of the response to reactive nitrogen species. In contrast, SoxR and OxyR, regulators of the E. coli defenses against superoxide-generating compounds and hydrogen peroxide, respectively, have minor roles. Moreover, additional regulators of the E. coli response to reactive nitrogen species remain to be identified because several of the induced genes were regulated normally in norR, fur, soxRS, and oxyR mutant strains. We propose that the E. coli transcriptional response to reactive nitrogen species is a composite response mediated by the modification of multiple transcription factors containing iron or redox-active cysteines, some specifically designed to sense NO and its derivatives and others that are collaterally activated by the reactive nitrogen species.

Bacterial Proteins↗
PubMed2004

Different regulation of ERK1/2 activation by beta-adrenergic receptor subtypes in adult mouse cardiomyocytes.

BACKGROUND: Increasing evidence suggests that stimulation of beta-adrenergic receptor (betaAR) activates mitogen-activated protein kinases (MAPKs), particularly extracellular signal-regulated kinase (ERK1/2) which is involved in the regulation of a multitude of cellular processes. However, the subtype-specific effects of betaAR stimulation on MAPKs remain to be elucidated. AIMS: In the present study, we determined whether beta(1)AR and beta(2)AR differ in regulating ERK1/2 activation in the myocardium. METHODS: To avoid complicated interactions between betaAR subtypes, we separately expressed either beta(1)AR or beta(2)AR using adenoviral gene transfer in adult mouse cardiac myocytes from beta(1)beta(2) double knockout mice. RESULTS: Stimulation of beta(1)AR by isoproterenol markedly increased ERK phosphorylation and activity by 2.1-fold in a time-dependent manner. In contrast, stimulation of beta(2)AR slightly decreased ERK activation. Furthermore, pretreatment of cells with pertussis toxin to disrupt Gi function did not affect the inhibitory effect of beta(2)AR on ERK1/2. CONCLUSIONS: We have shown that stimulation of cardiac betaAR subtypes differentially regulates ERK activation in adult mouse cardiomyocytes.

Journal Article↗
PubMed2004

Clinical benefit of zoledronic acid in patients with lung cancer and other solid tumors: analysis based on history of skeletal complications.

The results of a retrospective exploratory analysis of a phase III trial of zoledronic acid in patients with bone metastases secondary to lung cancer or other solid tumors are reported herein to assess the risk of skeletal-related events (SREs) and the efficacy of 4 mg zoledronic acid compared with placebo. The study is based on patient SRE history before study entry. Patients were stratified based on SRE history (eg, pathologic fracture, spinal cord compression, radiation therapy or surgery to bone, or hypercalcemia) before study entry, and SRE incidence over 21 months was analyzed. Of 507 patients randomized to 4 mg zoledronic acid or placebo, 131 completed the 9-month core phase and 69 entered the 12-month extension phase. Before study entry, 347 of 503 patients who were evaluable for efficacy (69%) experienced >/= 1 SRE; these patients had a higher risk of developing an SRE on study than patients with no prior SRE (odds ratio, 1.41). Among patients with an SRE before study entry, zoledronic acid reduced the risk of SREs by 31% (P = 0.009), reduced the mean skeletal morbidity rate (1.96 vs. 2.81 SREs per year for placebo; P = 0.030), and prolonged the median time to first SRE by nearly 4 months (215 days vs. 106 days for placebo; P = 0.011). Among patients with no SRE before study entry (n = 156), zoledronic acid reduced the risk of SREs by 23% (P = 0.308), reduced the mean skeletal morbidity rate (1.34 vs. 2.53 SREs per year for placebo; P = 0.332), and prolonged the median time to first SRE by 2.5 months (P = 0.534). This exploratory analysis demonstrates that patients with a history of SREs are at high risk for subsequent SREs, but zoledronic acid reduces skeletal morbidity regardless of SRE history.

Antineoplastic Agents↗
PubMed2004

[Study on elastic limit and relevant enclasp force of non-precious metal casting clasp].

OBJECTIVE: To investigate the elastic limit and relevant enclasp force of the non-precious metal casting clasp. METHODS: Casting clasp samples of five cobalt-chromium alloys and one 18 - 8 nickel-chromium alloy were made from prefabricated clasp wax by invesing, casting, sandblasting, and ultrasonic cleaning. The process of casting clasp samples deflected by loading and returned by unloading was tested and electric signals were collected by an omnipotent material machine. The analog electric signal was converted to digital signal by an analog to digital converter and stored in a computer. The elastic limit and the relevant enclasp force were analyzed using a relative software. RESULTS: The elastic limit and the relevant enclasp force of the casting clasp made from the 18 - 8 nickel-chromium alloy were smallest and those of the clasps made from the cobalt-chromium alloys in various brands were different. The range of the elastic limit of the cobalt-chromium alloy casting clasp with the length of 5.0 mm in undercut was 0.28 mm-0.33 mm and the relevant enclasp force was 14.42 g-19.28 g. CONCLUSIONS: In clinic, we should select the suitable undercut deepness wherein the cobalt-chromium alloy casting clasps, according to different brands of the casting alloy, undercut length, undercut slope, and the clasp thickness.

Chromium Alloys↗
PubMed2004

[Cardiomyocyte-like differentiation of human bone marrow mesenchymal stem cells after exposure of 5-azacytidine in vitro].

To investigate the potential of adult mesenchymal stem cells (hMSCs) derived from human bone marrow to undergo cardiomyogenic differentiation after exposure of 5-azacytidine in vitro. A small bone marrow aspirate was taken from the iliac crest of human volunteers, and hMSCs were isolated by 1.073 g/mL Percoll and cultured in the right cell culturing medium as previously described. The phonotypes of hMSCs were identified by flow cytometry. The stem cells were cultured in cell culture medium (as control) and medium mixed with 5-azacytidine (5-aza, 3, 5, 10 micromol/L) (n=5, respectively) for cellular differentiation. We examined respectively with immunohischemistry at 21 days of inducement on desmin, cardiac-specific cardiac troponin I (cTnI), GATA4 & connexin43. The ultrastructures of induced cells were examined by transmission electron microscope. The results indicated that the hMSCs showed a fibroblast-like morphology with vortex distribution in their peak propagation, and express high level of CD44 but negative for CD34 and CD45. 20%-30% cells grown after 5, 10 microl/L 5-aza treatment connected with adjoining cells and coalesced into myotube structures after 14 days. After 21 days of culturing, immunohistochemistry revealed expression of desmin, GATA4, cTnI and connexin43 in 5, 10 micromol/L showed positive, but no cardiac specific protein were found in neither 3 micromol/L nor in control group. The ratio of cTnI positive stained cells in 10 micromol/L group were higher than that in 5 micromol/L group (65.3+/-4.7% vs 48.2+/-5.4%, p<0.05). Electron microscopy revealed myofilaments were formed. The results indicated that purified hMSCs from adult bone marrow can be differentiated into cardiac-like muscle cells with 5-aza inducement in vitro and the differentiation is in line with the 5-aza concentration.

Adult↗
PubMed2004

Acidosis-induced p38 MAPK activation and its implication in regulation of cardiac contractility.

AIM: To determine the possible role of pH in mediating activation of p38 mitogen-activated protein kinase (MAPK) and the consequent function of activated p38 MAPK in regulating cardiac contractility. METHODS: Adult rat cardiomyocytes were isolated and cultured. Low pH media was used to induce intracellular acidosis and contraction of single cardiomyocyte was measured. RESULTS: Phosphorylation of p38 MAPK was increased during ischemia, and pHi was decreased. Intracellular acidosis activated p38 MAPK to a similar level as ischemia. Inhibition of p38 MAPK activation by SB203580, a specific inhibitor of p38 MAPK, reversed acidosis-mediated reduction of myocyte contractility. CONCLUSION: In adult rat cardiomyocytes, intracellular acidification activated p38 MAPK and decreased cardiac contractility. Pretreatment of cardiomyocytes with SB203580 completely blocked p38 MAPK activation and partially reversed acidosis-mediated decline of cardiac contractility.

Acidosis↗
PubMed2003

Structure-based carbon nanotube sorting by sequence-dependent DNA assembly.

Wrapping of carbon nanotubes (CNTs) by single-stranded DNA (ssDNA) was found to be sequence-dependent. A systematic search of the ssDNA library selected a sequence d(GT)n, n = 10 to 45 that self-assembles into a helical structure around individual nanotubes in such a way that the electrostatics of the DNA-CNT hybrid depends on tube diameter and electronic properties, enabling nanotube separation by anion exchange chromatography. Optical absorption and Raman spectroscopy show that early fractions are enriched in the smaller diameter and metallic tubes, whereas late fractions are enriched in the larger diameter and semiconducting tubes.

Anions↗