Imaging of myocardial infarction: comparison of magnevist and gadophrin-3 in rabbits

OBJECTIVES: This study was designed to determine the enhancement profile of a necrosis-specific contrast agent (gadophrin III) in comparison to a standard extracellular agent on T1-weighted magnetic resonance (MR) images in acute and chronic myocardial infarctions (MIs). BACKGROUND: Contrast-enhanced MR imaging demonstrated the ability to accurately quantify infarct size; however, some controversies persist about which contrast medium is best suited. METHODS: Fifteen rabbits underwent thoracotomy and permanent occlusion of a branch of the left coronary artery. Two animals died before imaging, eight were examined 48 h after occlusion and five animals were imaged six weeks following induction of infarction. All animals received 50 micromol/kg of gadophrin-3 24 h before the MR examination. Continuous short-axis views were collected using an inversion recovery turbo fast low angle shot sequence. Imaging was repeated 5 to 10 min following additional injection of 100 micromol/kg of Magnevist. The area of hyperenhancement demarcated following gadophrin-3 injection was compared with the region of hyperenhancement seen on gadophrin-3 plus Magnevist enhanced image using triphenyltetrazolium chloride (TTC) staining as the standard of reference. RESULTS: In acute MI the mean difference in size of hyperenhancement seen on the two different in vivo MR scans was -1.8 +/- 6.0 mm(2) (p > 0.05). Both measurements showed excellent agreement with TTC staining. Chronic MIs showed no enhancement with gadophrin-3, whereas application of Magnevist resulted in hyperenhancement. CONCLUSIONS; Standard extracellular contrast agents do not overestimate the size of acute MI. The combination of gadophrin-3 and Magnevist can distinguish acute and chronic myocardial injury because chronic MIs do not enhance with gadophrin-3.     

BMS-214662 potently induces apoptosis of chronic myeloid leukemia stem and progenitor cells and synergizes with tyrosine kinase inhibitors

Chronic myeloid leukemia (CML), a hematopoietic stem-cell disorder, cannot be eradicated by conventional chemotherapy or the tyrosine kinase inhibitor imatinib mesylate (IM). To target CML stem/progenitor cells, we investigated BMS-214662, a cytotoxic farnesyltransferase inhibitor, previously reported to kill nonproliferating tumor cells. IM or dasatinib alone reversibly arrested proliferation of CML stem/progenitor cells without inducing apoptosis. In contrast, BMS-214662, alone or in combination with IM or dasatinib, potently induced apoptosis of both proliferating and quiescent CML stem/progenitor cells with less than 1% recovery of Philadelphia-positive long-term culture-initiating cells. Normal stem/progenitor cells were relatively spared by BMS-214662, suggesting selectivity for leukemic stem/progenitor cells. The ability to induce selective apoptosis of leukemic stem/progenitor cells was unique to BMS-214662 and not seen with a structurally similar agent BMS-225975. BMS-214662 was cytotoxic against CML blast crisis stem/progenitor cells, particularly in combination with a tyrosine kinase inhibitor and equally effective in cell lines harboring wild-type vs mutant BCR-ABL, including the T315I mutation. This is the first report of an agent with activity in resistant and blast crisis CML that selectively kills CML stem/progenitor cells through apoptosis and offers potential for eradication of chronic phase CML.     

Validated quantitation of angiotensin II receptor antagonists (ARA-II) in human plasma by liquid-chromatography-tandem mass spectrometry using minimum sample clean-up and investigation of ion suppression

For the quantitation of angiotensin II receptor antagonists (ARA-II) in human plasma, a method using liquid-chromatography (LC)-electrospray ionization tandem mass spectrometry (MS/MS) has been developed with respect to simple sample clean-up and investigation of ion suppression effects. For sample preparation, protein precipitation using zinc sulphate and methanol showed advantages in speed, recovery, and reproducibility over solid-phase extraction. A triple quadrupole mass spectrometer (Sciex API 365) with turbo ionspray source was used for detection of compounds with multireaction monitoring (MRM) of two transitions per compound. Suppression effects caused by endogenous matrix compounds were investigated by post-column infusion of analytes and LC analysis of precipitates of blank plasma samples and could be excluded. A validation was performed for the ARA-II drugs (valsartan, irbesartan, losartan and its active metabolite EXP 3174, eprosartan, candesartan, and telmisartan). The developed method showed good intra- and interday precision (<12% relative standard deviation) and accuracy (<11.5% bias) at different concentrations for all the studied compounds. The calculated lower limits of quantitation were between 7 and 13 ng/mL, and the compounds were stable during the analytical process. These rather expensive drugs against hypertension are prescribed with increasing numbers in Europe and the industrialized nations. Complications might arise from overdosage or metabolic disorders. However, drug monitoring is not usually performed. Because the therapeutic concentrations range from a few nanograms to hundreds of nanograms per milliliter for the different drugs, and they are not amenable to gas chromatography/MS analysis because of their high molecular weight and polarity, the LC-MS/MS method is the golden standard for therapeutic drug monitoring and for clinical and forensic toxicology of ARA-II drugs.     

Human Neurospheres as Three-Dimensional Cellular Systems for Developmental Neurotoxicity Testing

Background

Developmental neurotoxicity (DNT) of environmental chemicals is a serious threat to human health. Current DNT testing guidelines propose investigations in rodents, which require large numbers of animals. With regard to the “3 Rs” (reduction, replacement, and refinement) of animal testing and the European regulation of chemicals [Registration, Evaluation, and Authorisation of Chemicals (REACH)], alternative testing strategies are needed in order to refine and reduce animal experiments and allow faster and less expensive screening.

Objectives

The goal of this study was to establish a three-dimensional test system for DNT screening based on human fetal brain cells.

Methods

We established assays suitable for detecting disturbances in basic processes of brain development by employing human neural progenitor cells (hNPCs), which grow as neurospheres. Furthermore, we assessed effects of mercury and oxidative stress on these cells.

Results

We found that human neurospheres imitate proliferation, differentiation, and migration in vitro. Exposure to the proapoptotic agent staurosporine further suggests that human neurospheres possess functioning apoptosis machinery. The developmental neurotoxicants methylmercury chloride and mercury chloride decreased migration distance and number of neuronal-like cells in differentiated hNPCs. Furthermore, hNPCs undergo caspase-independent apoptosis when exposed toward high amounts of oxidative stress.

Conclusions

Human neurospheres are likely to imitate basic processes of brain development, and these processes can be modulated by developmental neurotoxicants. Thus, this three-dimensional cell system is a promising approach for DNT testing.     

Limits of meta-analysis: methylphenidate in the treatment of adult attention-deficit hyperactivity disorder

Guidelines for the treatment of attention-deficit hyperactivity disorder (ADHD) in adults advocate methylphenidate as first-line treatment. The aim of this study was to review the effectiveness of methylphenidate treatment of adult ADHD and to examine the influence of methods on meta-analytic results. Electronic databases were searched to identify clinical trials comparing methylphenidate with placebo in the treatment of adult ADHD. Studies were summarised with meta-analytic methods. Subgroup analyses were conducted with respect to parallel group versus cross-over trials and self versus observer ratings. The relationship between dosage and effect size was explored by weighted regression analysis. The results were tested for publication bias, and several sensitivity analyses were performed. Findings and methods were compared with a previous meta-analysis. Eighteen studies met the inclusion criteria of which 16 were included in the meta-analysis. The overall effect size (d = 0.42) was significantly different from zero, but was only half the size expected on the basis of a previous meta-analysis. No significant differences could be observed in the subgroup analyses. The regression analysis showed no significant influence of mean daily dose on effect size. These results contradict findings of a previous meta-analysis and challenge guideline recommendations. Methodological issues in meta-analyses are discussed.     

Current bioinformatics tools in genomic biomedical research (Review)

On the advent of a completely assembled human genome, modern biology and molecular medicine stepped into an era of increasingly rich sequence database information and high-throughput genomic analysis. However, as sequence entries in the major genomic databases currently rise exponentially, the gap between available, deposited sequence data and analysis by means of conventional molecular biology is rapidly widening, making new approaches of high-throughput genomic analysis necessary. At present, the only effective way to keep abreast of the dramatic increase in sequence and related information is to apply biocomputational approaches. Thus, over recent years, the field of bioinformatics has rapidly developed into an essential aid for genomic data analysis and powerful bioinformatics tools have been developed, many of them publicly available through the World Wide Web. In this review, we summarize and describe the basic bioinformatics tools for genomic research such as: genomic databases, genome browsers, tools for sequence alignment, single nucleotide polymorphism (SNP) databases, tools for ab initio gene prediction, expression databases, and algorithms for promoter prediction.     

Evaluating the role of zinc in the occurrence of fibrosis of the skin: A preclinical study

Purpose

To investigate the possible role of Zn as a trigger for NSF we were using a previously established preclinical model. The depletion of endogenous Zinc ions (Zn) caused by the administration of gadolinium‐based contrast agents (GBCAs) has been suggested as a possible pathomechanism for nephrogenic systemic fibrosis (NSF).

Materials and Methods

In the Zn supplementation study, rats were injected with Gadodiamide, Omniscan, and Magnevist with or without Zn supplementation. In the Zn depletion study, animals were kept on a Zn‐deficient diet or a special control diet and received injections of Omniscan, OptiMARK, Magnevist, Gadovist, and Gd‐EDTA. Gd, Zn, and Cu concentrations in tissue were measured and histology of the skin was performed.

Results

As seen in earlier studies, a difference in Gd concentration in the skin was observed following treatment with the different GBCAs. High Gd concentration in the skin correlated with the occurrence of NSF‐like skin lesions. We observed no differences in the occurrence of skin lesions between the Zn supplementation and the Zn‐deficient groups compared to their respective control groups.

Conclusion

We found no significant effect of Zn on the initiation of NSF‐like skin lesions. The results further support data from previous studies highlighting the importance of complex stability of the investigated GBCAs. J. Magn. Reson. Imaging 2009;30:374–383. © 2009 Wiley‐Liss, Inc.