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Clinical Neuroscience

SEPTEMBER 30, 2012

[Tissue water content determination based on T1 relaxation time of water and quantitative cerebral 1H MRS at 3T using water as an internal reference]

FILE Györgyi, BAJZIK Gábor, DÓCZI Tamás, ORSI Gergely, PERLAKI Gábor, LELOVICS Zsuzsanna, ARADI Mihály, SCHWARCZ Attila

[Objective - Application of a quantitative MR-spectroscopic method for 3T clinical scanners based on tissue water content as an internal reference. Patients and methods - Six (22±2 yrs) volunteers were involved in the study. We performed T1 relaxation time measurements in a particular slice of the brain at 1T and 3T. Based on the validated water content measurement at 1T, the correlation of relaxation time T1 and water content was determined at 3T. The resulting water content served as internal reference for the quantification of localizated MRspectroscopic measurement. Results - At 3T our method resulted in 37.6±0.5 mol/l and 46.4±1.5 mol/l tissue water content in the white and gray matter, respectively. Calibration based on water content led to following metabolite concentrations: N-acetyl-aspartate 7.79±0.67 mmol/l; creatine 3.76±0.28 mmol/l; choline 3.68±0.47 mmol/l; myo-inositol 10.35±3.70 mmol/l in the white matter; and N-acetyl-aspartate 8.20±0.45 mmol/l; creatine 4.76±0.18 mmol/l; choline 2.64±0.35 mmol/l; myo-inositol 8.32±1.42 mmol/l in the grey matter. Conclusions - Tissue water content based on T1 value at 3T shows good accordance with gravimetric or other MR methods in the literature. Using it as an internal reference resulted in white matter metabolite concentrations that are in the range of previously published data. Comparing metabolite values of grey matter is more difficult because data in the literature substantially differ. The presented method is simple and easily applicable on any MR scanner without complicated correction and calibration steps.]

Lege Artis Medicinae

MAY 20, 2004

[IDENTIFYING HELICOBACTER PYLORI WITH DNA-BASED ASSAYS]

RUZSOVICS Ágnes, MOLNÁR Béla, TULASSAY Zsolt

[The DNA-based assays have the potential to be a powerful diagnostic tool given its ability to specifically identify H. pylori DNA. Markers used include general H. pylori structures and pathogenetic factors like ureaseA, cagA, vacA, iceA. DNA or bacterial RNA for polymerase chain reaction (PCR) assays can be collected from gastric biopsy, gastric juice, stool, buccal specimens. PCR can yield quantitative and genotyping results with sensitivity and specificity that approaches 100%. A clear trend in the direction of the determination of quantitative H. pylori infection by real-time PCR can be observed. Fluorescent in situ hybridisation (FISH) and restriction fragment length polymorphism (RFLP) are suggested for routine antibiotic resistance determination. To identify the DNA structure of organism and its virulence factors may be feasible by using oligonucleotide microarray specifically recognising and discriminating bacterial DNA and various virulence factors. DNA based H. pylori diagnosis yields higher sensitivity, however, specificity requires sophisticated labour environment and associated with higher costs.]

Lege Artis Medicinae

APRIL 20, 2003

[Proteomics - the new challenge]

HUDECZ Ferenc

[The term ”proteome” (proteome, PROTEin complement to a genOME) by now a generally accepted expression in biomedical science meaning a complete complements of proteins. The discipline ”proteomics”, coined after proteome, deals with the analysis of the complete set of proteins occurring in the living organism. This includes the identification and quantification of proteins, the determination of protein localisation, modifications, interactions, activities and function. Performing comparative studies is an important part of proteomics for the analysis of proteins in health and disease. The knowledge generated is already used for improved diagnostic procedures and development of new drugs and therapies. During the proteome analysis, as outlined in this paper, even very small quantities (concentrations) of proteins are measured, then the protein is identified and its structure is elucidated. This procedure is followed by functional studies. An important part of proteomics is the collection and validation of numerical databases suitable for data mining. There is a general understanding that methodology driven research (e.g. NMR, mass spectrometry, DNA chips) is also an integrated part of this discipline. It is already sensed that the analysis of proteome can lead to the discovery of new proteins proving targets for drug research and to the establishment of new procedures with a perspective of improved diagnosis and therapy.]

Hungarian Radiology

OCTOBER 20, 2009

[Ways of imaging the expression of vascular endothelial growth factor and its receptor]

KOROM Csaba, KARLINGER Kinga

[The vascular endothelial growth factor (VEGF) and its receptors (VEGFR) signal-transduction pathway play a key role in the regulation of angiogenesis. It was originally isolated as a selective mitogen for endothelial cells and as a powerful vascular permeability increasing factor. The vascular imaging techniques make the quantification and localization of blood vessels possible. They have been used to assess blood flow, oxygenation, and vascular permeability. Also, they can be used to examine the molecular and cellular difference in the vascular wall. To evaluate tumour vascularity, a multimodality approach is expanding. VEGF as the primary mediator for vascular-permeability is indirectly measurable with DCE-MRI (dynamic contrastenhanced MRI). MRI investigation can determine the ratio of deoxyhemoglobin/oxyhemoglobin in order to localize the hypoxic regions in vivo (BOLD [blood oxygen-level dependent] sequence and OMRI [Overhauser MRI]). In molecular MRI (mMRI), contrast agent-mediated alteration of tissue relaxation times can allow for the detection and localization of molecular disease markers. To localize the expression of VEGFR with SPECT and PET, antibodies and VEGF isoforms can be marked with isotopes. VEGFR is an excellent candidate for targeted ultrasound imaging since it is almost exclusively expressed on activated endothelial cells. Optical imaging is a relatively cheap method suitable so far primarily for small animal studies.]