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Michael D Reily

Publications and source records attributed to Michael D Reily.

11 recordsLinked to original sources
PubMed2006

DFTMP, an NMR reagent for assessing the near-neutral pH of biological samples.

A new NMR chemical shift standard and pH indicator, difluorotrimethylsilanylphosphonic acid (DFTMP), is described, and the utility of this reagent is demonstrated for in situ determination of pH in complex biofluids. The pH dependence of this reagent allows accurate in situ determination of aqueous solution pH to within an RMSE of 0.02 pH units over a pH range of 5 to 8. Advantages of this reagent over previously described pH-sensitive components include (1) lack of metal binding affinity, (2) minimal disturbance of endogenous spectral regions, and (3) the potential to function as a multinuclear pH indicator and chemical shift reference point for 19F, 1H, and 31P nuclei. This reagent will be generally useful for NMR experiments on biological systems where the pH needs to be accurately measured at the moment of data acquisition.

Animals↗
PubMed2006

Mechanisms and biomarkers of cardiovascular injury induced by phosphodiesterase inhibitor III SK&F 95654 in the spontaneously hypertensive rat.

The cardiovascular injury of the type III selective PDE inhibitor SK&F 95654 was investigated in SHR. Twenty-four hours after a single sc injection of 100 or 200 mg/kg of the drug, rats exhibited cardiomyocyte necrosis and apoptosis, interstitial inflammation, hemorrhage and edema, as well as mesenteric arterial hemorrhage and necrosis, periarteritis, EC and VSMC apoptosis, EC activation, and MC activation and degranulation. Elevated serum levels of cTnT and decreased cTnT immunoperoxidase staining on cardiomyocytes were detected in the drug-treated rats. Serum levels of alpha2-macroglobulin and IL-6 were significantly elevated following drug treatment. NMR spectral patterns of urine samples are significantly different between the drug-treated and control rats. These results indicate that measurement of serum cTnT, acute phase proteins, and cytokines as well as metabonomic urine profiles may serve as potential biomarkers for drug-induced cardiovascular injury in rats. Increased expression of CD63 on MC (tissue biomarker of MC), of nitrotyrosine on MC and EC (an indirect indicator of NO in vivo), and of iNOS on MC and EC (source of NO) suggest that NO produced by activated and degranulated MC as well as activated EC play an important role in SK&F 95654-induced mesenteric vascular injury.

Alanine Transaminase↗
PubMed2005

Metabonomic identification of two distinct phenotypes in Sprague-Dawley (Crl:CD(SD)) rats.

Genetic drift in animal populations has been a recognized concern for many years. Less understood is the potential for phenotypic "drift" or variation that is not related to any genetic change. Recently, stock Sprague-Dawley (Crl:CD(SD)) rats obtained from the Charles River Raleigh facility demonstrated a distinct endogenous urinary metabonomic profile that differed from historical control SD urine spectral profiles obtained over the past several years in our laboratory. In follow-up studies, the origin of the variant phenotype was narrowed down to animals of both sexes that were housed in one specific room (Room 9) in the Raleigh facility. It is likely that the two phenotypes are related to distinct populations of gut flora that particularly impact the metabolism of aromatic molecules. The most pronounced difference between the two phenotypes is the relative amounts of hippuric acid versus other aromatic acid metabolites of chlorogenic acid. Though both molecular species are present in either phenotype, the marked variation in levels of these molecules between the two phenotypes has led to the designation of high hippuric acid (HIP) and high chlorogenic acid metabolites (CA) phenotypes. Specific urinary components that distinguish the phenotypes have been thoroughly characterized by NMR spectroscopy with additional, limited characterization by LC-MS (high performance liquid chromatography coupled with mass spectrometry). Co-habitation of rats from the two phenotypes rapidly facilitated a switch of the CA phenotype to the historical Sprague-Dawley phenotype (HIP). The impact of these variant phenotypes on drug metabolism and long-term safety assessment studies (e.g., carcinogenicity bioassays) is unknown.

Animals↗
PubMed2005

Metabonomics in preclinical drug development.

Metabonomics has emerged as a key technology in preclinical drug discovery and development. The technology enables noninvasive systems assessment of untoward effects induced by candidate compounds characterising a broad spectrum of biological responses on an individual animal basis in a relatively rapid-throughput fashion, thus making it an ideal addition to early preclinical safety assessment. However, the implementation and interpretation of the technology and data it generates is not something that should be trivialised. Proper expertise in biological sciences, analytical sciences (nuclear magnetic resonance and/or mass spectrometry) and chemometrics should all be considered necessary prerequisites. If these factors are properly considered, the technology can add significant value as a tool for preclinical toxicologists.

Animals↗
PubMed2004

Metabolic activation of troglitazone: identification of a reactive metabolite and mechanisms involved.

Troglitazone (TGZ), the first glitazone used for the treatment of type II diabetes mellitus and removed from the market for liver toxicity, was shown to bind covalently to microsomal protein and glutathione (GSH) following activation by cytochrome P450 (P450). The covalent binding of (14)C-TGZ in dexamethasone-induced rat liver microsomes was NADPH-dependent and required the active form of P450; it was completely inhibited by ketoconazole (10 microM) and GSH (4 mM). The covalent binding in P450 3A4 Supersomes (9.2 nmol of TGZ Eq/nmol P450) was greater than that with P450 1A2 (0.7), 2C8 (3.7), 2C19 (1.4), 2E1 (0.6), and 2D6 (1.1) and 3A5 (3.0). The covalent binding in liver microsomes from rats pretreated with dexamethasone (5.3 nmol of TGZ Eq bound/nmol P450) was greater than that from rats pretreated with vehicle (3.5), beta-naphthoflavone (0.4), phenobarbital (1.1), or pyridine (2.5). A TGZ-GSH adduct was detected by liquid chromatography-tandem mass spectrometry and radioactivity detection with a deprotonated quasi-molecular ion [M-H](-) at m/z 745, with fragment ions at m/z 438 (deprotonated TGZ moiety), and at m/z 306 (deprotonated GSH moiety). The TGZ-GSH adduct was determined to be 5-glutathionyl-5-[4-(6-hydroxy-2,5,7,8-tetramethylchroman-2-ylmethoxy)benzyl]-thiazolidine-2,4-dione based on collision-induced dissociation fragmentation, and one- and two-dimensional NMR analysis of the isolated adduct. The synthetic 5-hydroxy TGZ and the benzylidene derivative of TGZ did not react with GSH or GSH ethyl ester. The mechanisms for metabolic activation of TGZ may involve an ultimate reactive sulfonium ion which could be formed from an initial sulfoxide followed by a formal Pummerer rearrangement, or a C5 thiazolidinedione radical or a sulfur cation radical.

Animals↗
PubMed2003

Contemporary issues in toxicology the role of metabonomics in toxicology and its evaluation by the COMET project.

The role that metabonomics has in the evaluation of xenobiotic toxicity studies is presented here together with a brief summary of published studies. To provide a comprehensive assessment of this approach, the Consortium for Metabonomic Toxicology (COMET) has been formed between six pharmaceutical companies and Imperial College of Science, Technology and Medicine (IC), London, UK. The objective of this group is to define methodologies and to apply metabonomic data generated using (1)H NMR spectroscopy of urine and blood serum for preclinical toxicological screening of candidate drugs. This is being achieved by generating databases of results for a wide range of model toxins which serve as the raw material for computer-based expert systems for toxicity prediction. The project progress on the generation of comprehensive metabonomic databases and multivariate statistical models for prediction of toxicity, initially for liver and kidney toxicity in the rat and mouse, is reported. Additionally, both the analytical and biological variation which might arise through the use of metabonomics has been evaluated. An evaluation of intersite NMR analytical reproducibility has revealed a high degree of robustness. Second, a detailed comparison has been made of the ability of the six companies to provide consistent urine and serum samples using a study of the toxicity of hydrazine at two doses in the male rat, this study showing a high degree of consistency between samples from the various companies in terms of spectral patterns and biochemical composition. Differences between samples from the various companies were small compared to the biochemical effects of the toxin. A metabonomic model has been constructed for urine from control rats, enabling identification of outlier samples and the metabolic reasons for the deviation. Building on this success, and with the completion of studies on approximately 80 model toxins, first expert systems for prediction of liver and kidney toxicity have been generated.

Animals↗
PubMed2002

Effect of dexamethasone on the metabonomics profile associated with phosphodiesterase inhibitor-induced vascular lesions in rats.

Metabonomics is the evaluation of the multiparametric metabolic response of biological systems to pathophysiological stimuli. High-resolution nuclear magnetic resonance (NMR) spectroscopy of biofluids coupled with pattern recognition-based chemometric analysis is an emerging approach to the study of metabonomics and may be used for the prediction of toxicity in vivo and for identification of surrogate markers of toxicity. Previously, we established that metabonomic analysis of urine samples has significant potential for identification of phosphodiesterase type 4 (PDE-4) inhibitor-induced vascular lesions in rats. It was not clear, however, whether the observed changes in metabonomics profile were related mechanistically to the pathogenesis of these vascular lesions or whether these changes were reflective primarily of the ensuing inflammatory response. In the present study, dexamethasone was used to suppress inflammation associated with vascular lesions induced in rats by the PDE-4 inhibitor CI-1018 and urine samples were evaluated for resultant changes in metabonomic profile. Female Wistar rats were given CI-1018 by gavage at 750 mg/kg with or without concurrent intraperitoneal administration of dexamethasone at 1 mg/kg for 4 days. Dexamethasone induced a characteristic lymphoid depletion and lymphocytolysis but no evidence of vascular lesions. Rats dosed with CI-1018 had mild vascular changes in liver and/or marked vascular lesions in mesentery characterized by medial necrosis, hemorrhage, and/or edema accompanied by perivascular mixed inflammatory cell infiltrates. Inflammatory infiltrates associated with these lesions were eliminated in rats given dexamethasone, yet minimal medial smooth muscle necrosis and degeneration still occurred, suggestive of etiologic changes rather than effects secondary to the inflammatory response. Principle component analysis of urine NMR spectra produced a clear pattern separation within 48 to 72 h between CI-1018-treated rats with vascular lesions and vehicle controls or rats given dexamethasone alone. There was no pattern separation, however, between rats given CI-1018 alone and rats given CI-1018 and dexamethasone concurrently, suggesting that CI-1018-induced urine spectral changes were associated with the vascular lesions, yet were independent of the inflammatory response. These findings provide new insight into the mechanism(s) of PDE inhibitor-induced vasculitis and support the potential use of metabonomics for developing reliable noninvasive methods for detecting vascular changes in rats.

Animals↗
PubMed2002

In vivo toxicity screening programs using metabonomics.

Metabonomics is an emerging technology that enables rapid in vivo screening for toxicity, disease state, or drug efficacy. The technology combines the power of high-resolution nuclear magnetic resonance (NMR) techniques with statistical data analysis methods to rapidly evaluate the metabolic "status" of an animal. Complimentary to other profiling technologies like proteomics and genomics, metabonomics provides a fingerprint of the small-molecules contained in a given biofluid through the time course of a study. This article reviews the steps in implementing a metabonomics-based screening program from study design through data analysis. While metabonomics is still a relatively new technology in comparison to the other "omics", published results from metabonomics studies demonstrate its potential impact in the drug discovery process by enabling the incorporation of safety endpoints much earlier in the drug discovery process, reducing the likelihood (and cost) of later stage attrition.

Algorithms↗