Classification of Urinary Calculi using Feed-Forward Neural Networks

Recent studies have shown that more than 80% of the analysed samples of urinary calculi in our  laboratory were mainly composed of four types of calculi, consisting of the following substances: (1) whewellite and weddellite, (2) whewellite, weddellite and uric acid, (3) whewellite, weddellite and struvite and (4) whewellite, weddellite and carbonate apatite. In this work the results of classification of these types of calculi (using their infrared spectra in the region 1450–450 cm–1) by feed-forward neural networks are presented. Genetic algorithms were used for optimization of neural networks and for selection of the spectral regions most suitable for classification purposes. The generalization abilities of the neural networks were controlled by an early stopping procedure. The best network architecture and the most suitable spectral regions were chosen using twentyfold cross-validation. The cross-validation error for the real samples varies from 5.3% to 5.9% misclassifications, which makes the proposed method a promising tool for the identification of these types of calculi.KEY WORDS:Urinary calculi, infrared spectroscopy, classification, neural networks, variable selection, genetic algorithms

Total Cu and speciation parameters for the shallow marine hydrothermal vent samples from Milos, Dominica and the Bay of Plenty

Hydrothermal vents at the seafloor release large volumes of metal-rich fluids into the ocean. Some of these metals are biologically essential (such as Fe), while others may be toxic (e.g. Cu). Organisms living at these habitats produce small organic molecules, ligands that are able to form complexes with different metals, to either enhance their bioavailability or to decrease their toxicity. While some deep-sea vents have been studied with respect to metal complexation, comparable studies at shallow marine hydrothermal vent systems are rather rare. In this study, total dissolved Cu concentrations ([Cu]T) and corresponding Cu binding ligand concentrations ([L]Cu) at the shallow water hydrothermal vent fields off the coast of Milos (Greece), Dominica (Lesser Antilles) and the Bay of Plenty (New Zealand) were examined by a voltammetric ligand titration, using competitive ligand equilibration-adsorptive stripping voltammetry (CLE-AdCSV). Milos, Dominica and the Bay of Plenty are three very different environments and our data show that they are relatively depleted in total dissolved Cu, compared to deep-sea hydrothermal vents where [Cu]T and [L]Cu concentrations up to 400 nM and 4000 nM have been found, respectively. In this data set, [Cu]T rises up to 21.53 nM, however, most samples are in the range of 0.5 nM-3 nM. [L]Cu varies between 2.07 nM and 23.9 nM, with one exception, reaching 56.8 nM. Conditional stability constants (Log K) range between 11.57 and 14.01. Assuming that the three investigated sites are representative for shallow marine hydrothermal vents, the Cu-flux into the ocean due to complexation appears to be relatively low compared to deep-sea systems. Our data indicate a stable complexation of Cu in most cases, which may lower the toxic effect of Cu on these mixed photic-chemosynthetic communities. However one pore water sample from Dominica showed an excess [Cu]T over [L]Cu, which would create a highly toxic environment for most marine organisms. We further show that ligand-Cu ratios and complex stability constants are in a similar range as the ones at deep-sea vents, which may indicate similar complexation parameters and processes at shallow and deep-sea hydrothermal vents

Engelen, Infrared and Raman spectra of magnesium ammonium phosphate hexahydrate (struvite) and its isomorphous analogues. I. Spectra of protiated and partially deuterated magnesium potassium phosphate hexahydrate

Abstract The Fourier transform infrared and Raman spectra of magnesium potassium phosphate hexahydrate and a series of its deuterated analogues were recorded and analyzed. By comparing the spectra recorded at room temperature with those obtained at the boiling temperature of liquid nitrogen and by studying the spectra of the series of partially deuterated MgKPO 4 ·H 2 O an assignment was proposed for the observed bands. The unusual behavior for bands originating from the n 4 modes of PO 4 32 ions in the Raman spectra of partially deuterated analogues of MgKPO 4 ·6H 2 O was explained by coupling and mixing of the n 4 ðPO 4 Þ mode and D 2 O librations.

The association of C3435T single-nucleotide polymorphism, Pgp-glycoprotein gene expression levels and carbamazepine maintenance dose in patients with epilepsy

Zoran Sterjev1, Gordana Kiteva Trencevska2, Emilija Cvetkovska2, Igor Petrov2, Igor Kuzmanovski2, Jasmina T Ribarska3, Aleksandra K Nestorovska1, Nadica Matevska1, Zorica Naumovska1, Suzana Jolevska-Trajkovic3, Aleksandar Dimovski1, Ljubica Suturkova11Institute of Pharmaceutical Chemistry, Faculty of Pharmacy Skopje, Republic of Macedonia; 2Clinic of Neurology, Faculty of Medicine, Skopje, Republic of Macedonia; 3Institute of Pharmaceutical Analysis, Faculty of Pharmacy Skopje, Republic of MacedoniaAbstract: The ABCB1 gene encodes the P-glycoprotein (Pgp) protein, which is thought to transport various antiepileptic drugs. The single nucleotide polymorphism (SNP) (C3435T) in exon 26 of this gene correlates with the altered expression levels of P-glycoprotein, range of drug response and clinical conditions. In order to investigate the influence of this polymorphism on the susceptibility to and efficacy of carbamazepine therapy, we evaluated the allelic frequency and genotype distribution of this variant in 162 epilepsy patients from the Republic of Macedonia. Statistically significant differences were detected neither in the allelic frequency and genotype distribution between carbamazepine-resistant and carbamazepine-responsive epilepsy patients nor between the subgroups of carbamazepine (CBZ)-responsive patients treated with different CBZ doses. However, the T-allele was enriched in CBZ-responsive patients who required higher maintenance CBZ doses, This observation was substantiated by the findings that the median total plasma levels were the lowest in patients with CC (20 µmol/L) followed by CT (23 µmol/L) and TT (29 µmol/L) genotypes. Patients with a CC genotype also had a higher likelihood of response compared to patients with CT or TT genotypes over a wide range (400–1000 mg/day) of initial doses of CBZ. The T allele showed a reduced expression of ~5% compared to the C allele in peripheral blood mononuclear cells in heterozygotes for the variant. This difference might be translated into ~10% difference in homozygotes for the variant, which would explain the trend towards a dose-dependent efficacy of the CBZ treatment in patients with different genotypes. A larger prospective study is warranted to clarify the clinical utility of a genotype-specific individualized CBZ therapy.Keywords: multidrug resistance protein 1 (MDR1), ABCB1 C3435T polymorphism, epilepsy treatment, carbamazepin