[Chronic paracetamol intoxication : under-diagnosed iatrogenic cause of metabolic acidosis with increased anion gap]. / L'intoxication chronique au paracétamol : cause iatrogène sous-diagnostiquée d'acidose métabolique à trou anionique augmenté.

The occurrence of metabolic acidosis with increased anion gap in the context of chronic paracetamol intoxication is an easily treatable clinical situation. Its rapid recognition is essential given its complete reversibility in the event of adequate management by eviction of the toxic agent, in this case paracetamol. It has an unknown cause and therefore potentially under-diagnosed, to be considered in the same way as the other more frequent etiologies. Because of this lack of knowledge, its frequency is probably underestimated considering the widespread consumption of paracetamol in the population.

La survenue d'une acidose métabolique à trou anionique augmenté dans le cadre d'une intoxication chronique au paracétamol est une situation clinique facile à traiter. Sa reconnaissance rapide est essentielle compte tenu de son entière réversibilité en cas de prise en charge adéquate par éviction de l'agent toxique, en l'occurrence le paracétamol. C'est une cause méconnue et de ce fait potentiellement sous-diagnostiquée, à envisager au même titre que les autres étiologies plus fréquentes. Du fait de cette méconnaissance, sa fréquence est probablement sous-estimée au vu de la consommation répandue de paracétamol au sein de la population.

Hepatitis E virus genotype 4 in a pig farm, Italy, 2013.

Zoonotic strains of hepatitis E virus (HEV) in Europe have been reported to belong to genotypes 3 and 4. In 2012 and 2013, 57 pig farms in Northern Italy that had previously resulted seropositive for HEV were surveyed for the presence of the virus, with positive samples subsequently genotyped. Hepatitis E RNA was identified in 17/57 (29·8%) seropositive farms. Phylogenetic analysis demonstrated that distinct subtypes of genotype 3 were circulating in the north-east of Italy; as well, for the first time in the Italian swine population, genotype 4 was identified and attributed to subtype d.

Pneumococcal phosphoglycerate kinase interacts with plasminogen and its tissue activator.

Streptococcus pneumoniae is not only a commensal of the nasopharyngeal epithelium, but may also cause life-threatening diseases. Immune-electron microscopy studies revealed that the bacterial glycolytic enzyme, phosphoglycerate kinase (PGK), is localised on the pneumococcal surface of both capsulated and non-capsulated strains and colocalises with plasminogen. Since pneumococci may concentrate host plasminogen (PLG) together with its activators on the bacterial cell surface to facilitate the formation of plasmin, the involvement of PGK in this process was studied. Specific binding of human or murine PLG to strain-independent PGK was documented, and surface plasmon resonance analyses indicated a high affinity interaction with the kringle domains 1-4 of PLG. Crystal structure determination of pneumococcal PGK together with peptide array analysis revealed localisation of PLG-binding site in the N-terminal region and provided structural motifs for the interaction with PLG. Based on structural analysis data, a potential interaction of PGK with tissue plasminogen activator (tPA) was proposed and experimentally confirmed by binding studies, plasmin activity assays and thrombus degradation analyses.

Neuropathic pain following spinal cord injury: what we know about mechanisms, assessment and management.

BACKGROUND: In biology, it is easy to understand how a damaged functional system may generate wrong signals, but why this should happen when the system is disconnected is less clear. For this reason, among other pain syndromes, neuropathic pain (NP) following spinal cord injury (SCI) leaves most questions unanswered. AIMS AND METHODS: Our purpose is to review current knowledge on NP after SCI, focusing on the mechanisms, assessment and management of the syndrome. RESULTS: The mechanisms responsible for NP following SCI are poorly understood: NP is classically considered a "central pain syndrome" but recent evidence from experimental models reveals a possible "peripheral sensitization". Assessment of NP following SCI is well-established: in addition to clinical evaluation and self-reported scales, many neurophysiological, radiological and microscopic investigations may be performed. The management of NP following SCI is very difficult: evidence of effective drugs is lacking and alternative new treatment approaches yield different outcomes. CONCLUSIONS: Recently clinical and instrumental tools have increased our knowledge on NP, suggesting that the discovery of new treatment agents will depend on an explanation of what changes after SCI: future research must point in this direction.

A strategy for intensive production of molybdenum-99 isotopes for nuclear medicine using CANDU reactors.

Technetium-99m is an important medical isotope utilized worldwide in nuclear medicine and is produced from the decay of its parent isotope, molybdenum-99. The online fueling capability and compact fuel of the CANDU(®)(1) reactor allows for the potential production of large quantities of (99)Mo. This paper proposes (99)Mo production strategies using modified target fuel bundles loaded into CANDU fuel channels. Using a small group of channels a yield of 89-113% of the weekly world demand for (99)Mo can be obtained.

Substrate uptake and protein stability relationship in mammalian histidine decarboxylase.

There is some evidence linking the substrate entrance in the active site of mammalian histidine decarboxylase and an increased stability against proteolytic degradation. In this work, we study the basis of this relationship by means of protein structure network analysis and molecular dynamics simulations. We find that the substrate binding to the active site influences the conformation of a flexible region sensible to proteolytic degradation and observe how formation of the Michaelis-Menten complex increases stability in the conformation of this region.

Structural features of mammalian histidine decarboxylase reveal the basis for specific inhibition.

For a long time the structural and molecular features of mammalian histidine decarboxylase (EC 4.1.1.22), the enzyme that produces histamine, have evaded characterization. We overcome the experimental problems for the study of this enzyme by using a computer-based modelling and simulation approach, and have now the conditions to use histidine decarboxylase as a target in histamine pharmacology. In this review, we present the recent (last 5 years) advances in the structure-function relationship of histidine decarboxylase and the strategy for the discovery of new drugs.

[Vitamin D deficiency in recently pregnant women]. / La carence en vitamine d chez les femmes enceintes en région liégeoise: un problème méconnu.

We have evaluated the prevalence of the 25-hydroxy vitamin D (25VTD) deficiency in recently pregnant women and new mothers in the area of Liege, Belgium. The study took place in November 2006. Twenty four women who underwent a positive pregnancy test and 65 new mothers were enrolled. The level of 25VTD did not differ between the two groups. Only 12% of the pregnant women and 14% of the new mothers (>12 ng/ml) had an optimal level of 25VTD (>30 ng/ ml). We also observed a severe 25VTD deficiency in 21% of pregnant women and 32% of new mothers. Our results showed that more than 80% of pregnant women and new mothers in the area of Liege presented a deficiency in 25VTD. In Belgium, daily vitamin supplementation of pregnant women is common, but the level of vitamin D3 concentration range from 10 microg (400 UI) to zero microg. In our area, vitamin D production in the skin is not always important enough to achieve optimal levels. Our data show that vitamin D supplementation of pregnant women is not enough and that 25VTD deficiency is not diagnosed in this high-risk population. Children born from deficient mothers will present a higher risk of suffering from bone mineral diseases as well as other pathologies, as type 1 diabetes or neurological disorders. Of course, this insufficiency will also have an impact on mother's bone reserve, but these mothers will also be at higher risk for preeclampsia.

Caracterización energética de la unión de 1, 3, 6 - naftalén trisulfonato al factor de crecimiento para fibroblastos ácido humano: implicaciones para su uso como agente anti-angiogénico / Energetic characterization of 1, 3, 6 - naphtalene trisulfonate binding to human acidic fi broblast growth factor: implications for its anti-angiogenic use

Se ha estudiado, mediante calorimetría isotérmica de reacción, la interacción del agente anticancerígeno 1,3,6-naftalén trisulfonato con el factor de crecimiento para fi broblastos ácido humano. La afi nidad decrece con el aumento de la fuerza iónica. A pH 7,0 y NaCl 0,15 M, la constante de unión de la proteína con el ligando se encuentra en el rango 102 – 103 M-1, una afi nidad dos órdenes de magnitud menor que la del FGFa por heparina. El cambio de entalpía favorece la interacción, siendo el cambio de entropía desfavorable. De la dependencia del cambio de entalpía con la temperatura se calculó un pequeño cambio en la capacidad calorífi ca del proceso, con un valor excepcionalmente positivo de 90 cal K-1mol-1. A partir de los datos termodinámicos medidos y de ecuaciones paramétricas establecidas en la literatura, se calcularon cambios en la superfi cie accesible al disolvente, tanto polar como apolar, que acompañan a la interacción. Los resultados se compararon con los medidos mediante resonancia magnética nuclear. El estudio incluye consideraciones de bioenergética estructural sobre el posible uso de 1,3,6-naftalén trisulfonato como agente antiangiogénico o como molécula líder para el desarrollo de fármacos anti-angiogénicos

The equilibrium interaction of anti-cancer agent 1,3,6-naphatalene trisulfonate with human acidic fi broblast growth factor has been studied by calorimetry. The affi nity decreases with increasing ionic strength. At pH 7.0 and 0.15 M NaCl concentration, a binding constant of the protein with the ligand was estimated in the 102 – 103 M-1 range, an affi nity two orders of magnitude lower than that of aFGF with heparin. The interaction is enthalpically driven, and the entropy change is unfavorable. A small heat capacity change with an unusual positive value of 90 cal K-1mol-1 was determined from the temperature dependence of the enthalpies. Changes in accessible apolar and polar surface areas in the interaction were calculated from the thermodynamic data obtained and parametric equations in the literature. The results were compared with those measured from NMR data. The study includes structural bioenergetic considerations about the possible use of 1,3,6-naphatalene trisulfonate as an anti-angiogenic agent itself, or as a lead for the development of anti-angiogenic drugs

Ligand-receptor interaction at the neural nicotinic acetylcholine binding site: a theoretical model.

Recent mutagenesis experiments have identified some of the functional amino acids that are essential in the interaction of nicotinic agents with the binding site of the neural nicotinic acetylcholine receptor (nAChR). Although this receptor is one of the best studied and characterized the lack of detailed experimental information regarding its quaternary structure has turned it into a challenge for computational chemistry. We have previously reported [J. Comput. Aided Mol. Design 13 (1999) 57-68] a computational protocol based on molecular mechanics and molecular dynamics (MD) where SER82, ASP83, TRP86, ASP89, TYR93, TYR190, TYR198 and ARG209 were placed around selected agonists and antagonists aided by stereoelectronic criteria. Explicit water molecules were used with the double goal of simulating aqueous environment and keeping the system from falling apart. The protocol was stable enough to allow the ligands to evolve to their thermodynamically most probable structure while maintaining the key interactions. In this communication we use the average model for the agonists (one average structure for each agonist) to calculate quantum mechanically the interactions of the binding site with one neurotransmitter acetylcholine (ACh, 1), as well as with two of the most potent agonists described so far [nicotine (2) and epibatidine (3)] and the modeled binding site. A wide variety of methods as well as basis sets were used in order to rationalise the best way to treat the problem. In this limited set of compounds, a good correlation between total interaction energies and biological affinity is observed.

The 5-HT(3) and nACh ionotropic receptors: a perspective from the computational chemistry point of view.

Recent contributions applying Computational Chemistry to serotonin-3 and nicotinic acetylcholine ionotropic receptors are reviewed. These two receptors constitute a good example for the examination of the computational protocols that have been used to understand how they work. On the one hand, (5-HT(3)R) receptor mapping techniques have been mostly employed in its study and very few examples of receptor fitting have been appeared. On the other hand, (nAChR) has been studied mainly from the receptor fitting point of view, although many contributions using receptor mapping exist. In the first case, antagonists seems to be more important that agonists, so more works are devoted to them. In the second case, agonist development is the main issue. Although far for being complete, in either of the cases we have working pharmacophores as well as 3D models for their binding sites that are ready to be used as a starting guess to design potential drugs. It is noteworthy that the absence of crystallographic structure for these receptors has motivated the interest in their study, constituting an interesting and challenging field. Mutagenesis experiments have allowed the establishment of main amino acids that are essential in the receptor functioning and then, interaction models have been postulated. Although most of the models are speculative in nature, some of them have been proved to be valuable tools for drug design. This scientific field is already open and many areas are still unexplored. Computational tools for treating these issues exist in a wide variety and their rational application would produce the answers to the structure and functioning of these receptors.

The treatment of gastroesophageal reflux disease with proton-pump inhibitors and its implications on managed care--clinical overview of gastroesophageal reflux disease. Roundtable discussion.

The importance of gastroesophageal reflux disease (GERD) to managed health care systems cannot be overestimated. It contributes significantly to the use of health care resources, including doctor's services, medication consumption, and diagnostic testing. A roundtable meeting of 13 managed care experts was convened January 23, 2001 in Dallas, to discuss the implications of GERD on the managed care system. The following proceedings are published in five sections. In the first part, Jeffrey Danzig, MD, a gastroenterologist, provides the clinical foundation for the discussion, based on the existing literature and his personal practice.

Effect of pravastatin-to-simvastatin conversion on low-density-lipoprotein cholesterol.

The effects of a pravastatin-to-simvastatin conversion program on low-density-lipoprotein (LDL) cholesterol levels were studied. Patients receiving pravastatin at a Veterans Affairs medical center were switched to simvastatin beginning in 1997. The dosage of simvastatin was based on the additional percent reduction in LDL cholesterol needed to achieve the goal specified by the National Cholesterol Education Program. The primary endpoint was the change in the percentage of patients meeting their LDL cholesterol goal at baseline and follow-up. Changes in lipid indices, the relative risk (RR) of coronary heart disease (CHD), and program costs were also evaluated. A total of 1032 patients completed the program. The mean +/- S.D. daily doses of pravastatin and simvastatin were 25.2 +/- 11.3 and 22.7 +/- 13.3 mg, respectively. Median baseline and follow-up LDL cholesterol concentrations were 116 and 99 mg/dL, respectively (p < 0.001). Overall, 44% of the patients met their LDL cholesterol goal while taking pravastatin, compared with 69% after conversion to simvastatin (p < 0.001). The predicted mean RR of a future CHD event (based on changes in serum lipids) was 0.87 (95% confidence interval, 0.83-0.91) four years after conversion. The total cost of the program was $40,644 in the first year, and there was a net saving thereafter. Therapeutic interchange between pravastatin and simvastatin increased the number of patients meeting their LDL cholesterol goal.

Superimposition-based protocol as a tool for determining bioactive conformations. I. Application to ligands of the glycinergic receptor (GlyR).

The natural templates (NT) approach, which is a superimposition-based protocol that has been successfully employed in several studies, is here applied to ligands of the glycine ligand-gated ion channel receptor. Bioactive conformations for glycine and its analogs were obtained using strychnine (a natural and specific competitive antagonist) as template. Experimental evidence was used to guide the superimposition protocol. Three essential regions have been defined in strychnine's structure that serve as a pharmacophore for agonist and antagonist activities. Reasonable alignments of known ligands were found in the majority of the cases. Molecular mechanics (i.e., conformational searches for the relatively flexible ligands) and molecular dynamics (for relatively rigid ligands such as strychnine and 5,6,7,8-tetrahydro-4H-isoxazolo[3,4-d]azepin-3-ol) were used to assess the energetic accessibility of the proposed bioactive conformations.

Myo-inositol hexasulphate and low molecular weight heparin binding to human acidic fibroblast growth factor: a calorimetric and FTIR study.

The interaction of an amino-terminal-truncated 139 amino-acids form of human acidic fibroblast growth factor with myo-inositol hexasulphate and low molecular weight (3500 g mol(-1)) heparin has been studied by isothermal titration calorimetry, differential scanning calorimetry and Fourier transform infrared spectroscopy. A slightly higher affinity for the monosaccharide has been measured. The binding of the ligands causes an increase of 13--15 degrees C in the melting temperature of the free protein (45 degrees C). From measured enthalpy and heat capacity changes, calculations of changes in accessible surface areas have been made. These calculations, together with infrared spectroscopy data, indicate that a small conformational change is induced by the binding of both ligands. This conformational change would affect the tertiary structure, not the secondary one.

Superimposition-based protocol as a tool for determining bioactive conformations. II. Application to the GABA(A) receptor.

The natural templates (NT) superimposition method is used to determine the pharmacophoric requirements of the A subtype of the gamma-aminobutyric acid (GABA) receptor. Bioactive conformations for antagonists and agonists are found by superimposing them on a relatively rigid alkaloid bicuculline, which itself is a competitive antagonist at this ligand-gated ion channel receptor. As has been usual in the application of this modeling method, consideration of available experimental data is the cornerstone for obtaining realistic models. The identification of two substructural fragments of bicuculline permitted classification of the ligands. Analysis of the antagonists and agonists with respect to the two substructural fragments revealed two bioactive conformations of the highly flexible GABA molecule, one of which is extended with the nonhydrogenic atoms roughly coplanar torsional angles of -37 and -179 degrees at N-C-C-C and C-C-C-C (carboxyl), respectively. The second bioactive compound is clearly non planar (torsional angles of -81 and -109 degrees at N-C-C-C and C-C-C-C (carboxyl), respectively).

Energetics of myo-inositol hexasulfate binding to human acidic fibroblast growth factor effect of ionic strength and temperature.

The binding of myo-inositol hexasulfate to an N-terminal truncated 132-amino-acid human acidic fibroblast growth factor form was studied by isothermal titration calorimetry. The technique yields values for the enthalpy change and equilibrium constant, from which the Gibbs energy and entropy change can also be calculated. Experiments in different buffers and pH values show that the proton balance in the reaction is negligible. Experiments at pH 7.0 in the presence of 0.2-0.6 M NaCl showed that the enthalpy and Gibbs energy changes parallel behaviour with ionic strength change, with values in the -21 to -11 kJ x mol(-1) range in the first case and in the -31 to -22 kJ x mol(-1) range in the second. No dependence of entropy on ionic strength was found, with a constant value of approximately 35 J x K(-1) x mol(-1) at all ionic strengths studied. The results can be interpreted in molecular terms by a model in which competitive binding of 3-4 chloride ions to the myo-inositol-binding site is assumed. Isothermal titration calorimetry was also performed at different temperatures and yielded a value of -142+/-13 J x K(-1) x mol(-1) for the heat-capacity change at pH 7.0 and 0.4 M NaCl. Using different parametric equations in the literature, changes on ligand binding in the range -100 to -200 A2 in solvent-accessible surface areas, both polar and apolar, were calculated from thermodynamic data. These values suggest a negligible overall conformational change in the protein when the ligand binds and agree closely with calculations performed with NMR structural data, in which it is shown that the most important negative change in total solvent-accessible surface area occurs in the amino acids Ile56, Gln57, Leu58 and Leu149, in the high-affinity receptor-binding region of the protein.