Clustering and colocalization in transmission immunoelectron microscopy: a brief review

This mini-review tries to summarize the state of the art of stereological and statistical approaches used in clustering (in single immunogold labelling) and colocalization (in double immunogold labelling) studies of gold particles in transmission immunoelectron microscopy. The point pattern analysis may be useful to compare experimental pattern data to the null hypothesis of complete spatial randomness (CSR), and, furthermore to quantify the amount of clustering and/or colocalization. In particular, this paper gives an overview about the most recent literature on the subject and different approaches will be only briefly summarized.     

Warfarin Sodium Stability in Oral Formulations

Warfarin sodium is a low-dose pharmaceutical blood thinner that exists in two forms: the clathrate form and the amorphous form. In commercially available warfarin sodium oral suspension, the active pharmaceutical ingredient (API) is added in the amorphous state. This study investigates the apparent instability of the commercially available warfarin liquid oral formulation using Raman and IR spectroscopy, X-ray diffraction, differential scanning calorimetry, UV spectroscopy, and optical microscopy. Warfarin, not its sodium salt, was identified as the undissolved solid existing in the suspension. This was found to be due to the dissociation of sodium salt and the protonation of the warfarin ion in the liquid phase, which triggered the crystallization of the sparingly soluble unsalted form. The coexistence of protonated and unprotonated warfarin ions in the supernatant, as detected by Raman and UV spectroscopy, confirmed this assumption. Study of the dissolution of warfarin sodium amorphous salt and crystalline sodium clathrate in the placebo and pure water verified the results. The effect of pH and temperature on warfarin precipitation was also explored.     

Magnetic resonance spectroscopy: a noninvasive diagnosis of gliomatosis cerebri

Gliomatosis cerebri (GC) is characterized by a diffuse infiltration of neoplastic glial cells with preservation of neuronal architecture. It can be very difficult to diagnose during life because the clinical manifestations are protean and tests are often nondiagnostic. The diagnosis of GC needs to be based on radiological, clinical and pathological criteria. We present a patient with GC, which initially presented as acute stroke attack. We discuss the usefulness of noninvasive methods, such a MR spectroscopy, in the diagnosis, grading and management of GC.     

First palladium(II) and platinum(II) complexes from employment of 2,6-diacetylpyridine dioxime: synthesis, structural and spectroscopic characterization, and biological evaluation

Employment of the monoanion of 2,6-diacetylpyridine dioxime (dapdoH(2)) as a tridentate chelate in palladium(II) and platinum(II) chemistry is reported. The syntheses, crystal structures, spectroscopic and physicochemical characterization, and biological evaluation are described of [PdCl(dapdoH)] (1) and [PtCl(dapdoH)] (2). Reaction of PdCl(2) with 2 equivs of dapdoH(2) in MeOH under reflux gave 1, whereas the same reaction with PtCl(2) in place of PdCl(2) gave 2 in comparable yields (70-80%). The divalent metal center in both compounds is coordinated by a terminal chloro group and a N,N',N"-tridentate chelating (η(3)) dapdoH(-) ligand. Thus, each metal ion is four coordinate with a distorted square planar geometry. Characterization of both complexes with (1)H and (13)C NMR and UV-vis and electrospray ionization mass spectroscopies confirmed their integrity in DMSO solutions. Interaction of the complexes with human and bovine serum albumin has been studied with fluorescence spectroscopy, revealing their affinity for these proteins with relatively high values of binding constants. UV study of the interaction of the complexes with calf-thymus DNA (CT DNA) has shown that they can bind to CT DNA, and the corresponding DNA binding constants have been evaluated. Cyclic voltammograms of the complexes in the presence of CT DNA solution have shown that the interaction of the complexes with CT DNA is mainly through intercalation, which has been also shown by DNA solution viscosity measurements. Competitive studies with ethidium bromide (EB) have revealed the ability of the complexes to displace the DNA-bound EB, suggesting competition with EB. The combined work demonstrates the ability of pyridyl-dioxime chelates not only to lead to polynuclear 3d-metal complexes with impressive structural motifs and interesting magnetic properties but also to yield new, mononuclear 4d- and 5d-metal complexes with biological implications.     

A multicriteria accreditation system for information technology skills and qualifications

Employees must acquire new competences and qualifications throughout their lives, in order to be able to deal with the multiple changes in the labour market. The specific knowledge and competences, acquired either formally or non-formally, must be recognized so that they can be transferred and utilized. The existing titles of studies and accreditation mechanisms do not generally cover this need. This paper aims to propose an integrated approach for the evaluation of information technology knowledge and skills, regardless of where and how they have been acquired, so as to apply a continuous education and training policy. The proposed multicriteria methodology for the evaluation of qualifications and skills concerns candidates wishing to be accredited in an information technology specialization or profession. The methodology refers to the evaluation of the professional experience, studies and vocational training of the candidates for accreditation. It contains the analysis and modelling of the qualitative criteria as well as the implementation of multicriteria aggregation–disaggregation techniques attributing value to each criterion. Then, the candidates are classified in categories of professionals using the Electre Tri method, accepting as input data the multicriteria assessments on each criterion. The proposed evaluation approach has been adapted to the Greek educational system and is applied to a specific example of candidate.     

Performance of octene in fluorous biphasic hydroformylation: octene distribution and reversible transfer between perfluoromethylcyclohexane and nonanal

During fluorous biphasic hydroformylation 1-octene is transferred from the fluorous into the organic product phase and then from the product layer back to the fluorous layer again, due to the immiscibility of nonanal with PFMCH. The effect of the temperature and the total amount of octene on the above behaviour were also studied.     

Synthesis,Kinetic and Conformational Studies of 2-Substituted-5-(β-d-glucopyranosyl)-pyrimidin-4-ones as Potential Inhibitors of Glycogen Phosphorylase

Dysregulation of glycogen phosphorylase, an enzyme involved in glucose homeostasis, may lead to a number of pathological states such as type 2 diabetes and cancer, making it an important molecular target for the development of new forms of pharmaceutical intervention. Based on our previous work on the design and synthesis of 4-arylamino-1-(β-d-glucopyranosyl)pyrimidin-2-ones, which inhibit the activity of glycogen phosphorylase by binding at its catalytic site, we report herein a general synthesis of 2-substituted-5-(β-d-glucopyranosyl)pyrimidin-4-ones, a related class of metabolically stable, C-glucosyl-based, analogues. The synthetic development consists of a metallated heterocycle, produced from 5-bromo-2-methylthiouracil, in addition to protected d-gluconolactone, followed by organosilane reduction. The methylthio handle allowed derivatization through hydrolysis, ammonolysis and arylamine substitution, and the new compounds were found to be potent (μM) inhibitors of rabbit muscle glycogen phosphorylase. The results were interpreted with the help of density functional theory calculations and conformational analysis and were compared with previous findings.     

Deployment of response surface methodology to optimise recovery of grape (Vitis vinifera) stem polyphenols

A 2³-full factorial design and response surface methodology were deployed to assess some basic factors (time, % ethanol and pH) affecting profoundly the extractability of polyphenolic phytochemicals from grape (Vitis vinifera) stems. In an effort to obtain a thorough insight into the applicability of the models established, stem extracts from three different varieties were tested, by determining several indices of the polyphenolic composition, such as total polyphenol (TP), total flavanol (TFl), total flavone (TFn) and proanthocyanidin (PC) concentration. It was shown that the models generated can adequately predict the recovery levels for each polyphenol group, but the optimal conditions predicted for TP, TFl, TFn and PC recovery varied significantly. Notable differences were also seen among the different varieties. Correlation of the polyphenol indices with the antiradical activity and reducing power of the extracts indicated that the PC fraction might exert strong effects, while the influence of other groups was not apparent. Examination of the optimally obtained extracts using liquid chromatography-mass spectrometry revealed that the most prominent compounds were caftaric acid, flavanols and derivatives thereof, as well as dehydroflavonols and flavonols.     

Efficient Atropodiastereoselective Access to 5,5′‐Bis‐1,2,3‐triazoles: Studies on 1‐Glucosylated 5‐Halogeno 1,2,3‐Triazoles and Their 5‐Substituted Derivatives as Glycogen Phosphorylase Inhibitors

Whereas copper‐catalyzed azide–alkyne cycloaddition (CuAAC) between acetylated β‐D ‐glucosyl azide and alkyl or phenyl acetylenes led to the corresponding 4‐substituted 1‐glucosyl‐1,2,3‐triazoles in good yields, use of similar conditions but with 2 equiv CuI or CuBr led to the 5‐halogeno analogues (>71 %). In contrast, with 2 equiv CuCl and either propargyl acetate or phenyl acetylene, the major products (>56 %) displayed two 5,5′‐linked triazole rings resulting from homocoupling of the 1‐glucosyl‐4‐substituted 1,2,3‐triazoles. The 4‐phenyl substituted compounds (acetylated, O‐unprotected) and the acetylated 4‐acetoxymethyl derivative existed in solution as a single form (d.r.>95:5), as shown by NMR spectroscopic analysis. The two 4‐phenyl substituted structures were unambiguously identified for the first time by X‐ray diffraction analysis, as atropisomers with aR stereochemistry. This represents one of the first efficient and highly atropodiastereoselective approaches to glucose‐based bis‐triazoles as single atropisomers. The products were purified by standard silica gel chromatography. Through Sonogashira or Suzuki cross‐couplings, the 1‐glucosyl‐5‐halogeno‐1,2,3‐triazoles were efficiently converted into a library of 1,2,3‐triazoles of the 1‐glucosyl‐5‐substituted (alkynyl, aryl) type. Attempts to achieve Heck coupling to methyl acrylate failed, but a stable palladium‐associated triazole was isolated and analyzed by ¹H NMR and MS. O‐Unprotected derivatives were tested as inhibitors of glycogen phosphorylase. The modest inhibition activities measured showed that 4,5‐disubstituted 1‐glucosyl‐1,2,3‐triazoles bind weakly to the enzyme. This suggests that such ligands do not fit the catalytic site or any other binding site of the enzyme.     

Reactions of 2,3-bishydroxyimino-1,2,3,4-tetrahydro-quinoxalines and 2,3-bishydroxyimino-2,3-dihydro-4H-1,4-benzoxazines with ethyl chloroformate

Bishydroxyiminoquinoxalines 3a-b react with ethyl chloroformate 4 to afford the furazano[3,4-b]quinoxalines 5a-b . Bishydroxyiminobenzoxazines 6a-c on treatment with 4 are converted into the fused oxadiazolones 7a-c and 8a-c along with the bisethoxycarbonyloxyimino-derivatives 9a-c . From the reactions of 4 with the oxanilide dioximes 12a-c compounds 13a-c and 14a-b are obtained.