Quantitative combination of volumetric MR imaging and MR spectroscopy data for the discrimination of meningiomas from metastatic brain tumors by means of pattern recognition

The analysis of information derived from magnetic resonance imaging (MRI) and spectroscopy (MRS) has been identified as an important indicator for discriminating among different brain pathologies. The purpose of this study was to investigate the efficiency of the combination of textural MRI features and MRS metabolite ratios by means of a pattern recognition system in the task of discriminating between meningiomas and metastatic brain tumors. The data set consisted of 40 brain MR image series and their corresponding spectral data obtained from patients with verified tumors. The pattern recognition system was designed employing the support vector machines classifier with radial basis function kernel; the system was evaluated using an external cross validation process to render results indicative of the generalization performance to “unknown” cases. The combination of MR textural and spectroscopic features resulted in 92.15% overall accuracy in discriminating meningiomas from metastatic brain tumors. The fusion of the information derived from MRI and MRS data might be helpful in providing clinicians a useful second opinion tool for accurate characterization of brain tumors.     

Pattern recognition system for the discrimination of multiple sclerosis from cerebral microangiopathy lesions based on texture analysis of magnetic resonance images

In this study, a pattern recognition system has been developed for the discrimination of multiple sclerosis (MS) from cerebral microangiopathy (CM) lesions based on computer-assisted texture analysis of magnetic resonance images. Twenty-three textural features were calculated from MS and CM regions of interest, delineated by experienced radiologists on fluid attenuated inversion recovery images and obtained from 11 patients diagnosed with clinically definite MS and from 18 patients diagnosed with clinically definite CM. The probabilistic neural network classifier was used to construct the proposed pattern recognition system and the generalization of the system to unseen data was evaluated using an external cross validation process. According to the findings of the present study, statistically significant differences exist in the values of the textural features between CM and MS: MS regions were darker, of higher contrast, less homogeneous and rougher as compared to CM.     

Enhancing the discrimination accuracy between metastases, gliomas and meningiomas on brain MRI by volumetric textural features and ensemble pattern recognition methods

Three-dimensional (3D) texture analysis of volumetric brain magnetic resonance (MR) images has been identified as an important indicator for discriminating among different brain pathologies. The purpose of this study was to evaluate the efficiency of 3D textural features using a pattern recognition system in the task of discriminating benign, malignant and metastatic brain tissues on T1 postcontrast MR imaging (MRI) series. The dataset consisted of 67 brain MRI series obtained from patients with verified and untreated intracranial tumors. The pattern recognition system was designed as an ensemble classification scheme employing a support vector machine classifier, specially modified in order to integrate the least squares features transformation logic in its kernel function. The latter, in conjunction with using 3D textural features, enabled boosting up the performance of the system in discriminating metastatic, malignant and benign brain tumors with 77.14%, 89.19% and 93.33% accuracy, respectively. The method was evaluated using an external cross-validation process; thus, results might be considered indicative of the generalization performance of the system to "unseen" cases. The proposed system might be used as an assisting tool for brain tumor characterization on volumetric MRI series.     

Trace metal ion preconcentration for Flame Atomic Absorption by an Immobilized N,N,N′-tri-(2-pyridyl-methyl)ethylene diamine (TriPEN) chelate ion exchanger in a flow injection system

Summary Trace Metal Ion P reconcentration for Flame Atomic Absorption by an Immobilized N,N,N-tri-(2-pyridylmetkyl)ethylene diamine (TriPEN) Chelate Ion Exchanger in a Flow Injection System Chelating groups of N,N,N-tri-(2-pyridyl-methyl)ethyIene diamine (TriPEN) were synthesized on the surface of porous glass. A 100l column of the chelate ion exchanger was incorporated into a flow injection manifold with a flame atomic absorption spectrometer. Metal ions from samples (<1 ml to>80 ml) were retained on the chelate ion exchanger until an injection of acid displaced them into the flame. A peak-shaped absorbance curve was recorded. The use of immobilized TriPEN for preconcentration of metals from dilute solution and for matrix modifications was demonstrated.     

A new approach to the synthesis of substituted 2(1H)-quinolinones

A new synthetic approach for the preparation of substituted 2(1H)-quinolinones 5 from readily available anilines has been developed. The four step procedure resulted in the synthesis of a variety of substituted 2(1H)-quinolinones in good yields and under mild reaction conditions.     

New synthesis of isoxazolidines

A new synthesis of 5-substituted isoxazolidines was developed by direct isoxazolidine ring formation of allylic hydroxylamines under acidic conditions. The cyclization process is an electrophilic S_N1 type reaction. The formed carbocation intermediate is stabilized by electron rich groups (i.e., phenyl). A moiety that mediates oxonium ion formation (i.e., para-methoxy) accelerates the rate of product formation.     

Structure-based design of estrogen receptor-beta selective ligands

We present the structure-based optimization of a series of estrogen receptor-beta (ERbeta) selective ligands. X-ray cocrystal structures of these ligands complexed to both ERalpha and ERbeta are described. We also discuss how molecular modeling was used to take advantage of subtle differences between the two binding cavities in order to optimize selectivity for ERbeta over ERalpha. Quantum chemical calculations are utilized to gain insight into the mechanism of selectivity enhancement. Despite only two relatively conservative residue substitutions in the ligand binding pocket, the most selective compounds have greater than 100-fold selectivity for ERbeta relative to ERalpha when measured using a competitive radioligand binding assay.     

Facile synthesis of novel spiro[azetidine-2,4′(1′H)-isoquinoline-1′,3′,4(2′H)-triones]

A convenient general method for the synthesis of a new heterocycle, spiro[azetidine-2,4′(1′H)-iso-quinoline-1′,3′,4(2′H)-trione] is described. The key intermediate 2 was prepared by direct halogenation of position-4 of acid 3 with thionyl chloride, and subsequent treatment of the generated 4-Cl, 4-acetyl chloride 11 with a THF/NH₃ solution at low temperature.     

On-line trace metal enrichment and matrix isolation in atomic absorption spectrometry by a column containing immobilized 8-quinolinol in a flow-injection system

Metal ions (Cu²⁺, Co²⁺, Cd²⁺, Ni²⁺, Pb²⁺, Zn²⁺) were concentrated quantitatively and isolated from the sample matrix by a colum