Déficit de memoria en una muestra de pacientes con dolor crónico / Memory impairment in a sample of patients with chronic pain

IntroducciónEs relativamente frecuente que los pacientes con dolor crónicose quejen de problemas de memoria y concentración. Históricamente,este hecho se ha relacionado con la medicación dirigida al control del dolor, con el estado de ánimo y con elhecho de padecer dolor crónico.ObjetivosConocer si las quejas subjetivas de pérdida de memoria querefieren los pacientes se objetivan en su ejecución en pruebasneuropsicológicas. En segundo lugar, estudiar si hay algunadiferencia en el rendimiento en dichas pruebas entre pacientescon dolor crónico que presentan sintomatología depresivaasociada y aquellos que no presentan dicha sintomatología.Por último, analizar si existe alguna relación entre la intensidaddel episodio depresivo que padece el paciente con dolorcrónico y el rendimiento en pruebas neuropsicológicas queevalúan atención y memoria.MétodoSe trata de un estudio observacional transversal en el que participaronpacientes derivados por la Unidad de Dolor del HospitalUniversitario “Del Río Hortega” con problemas de dolorcrónico y queja subjetiva de pérdida de memoria.ConclusionesÚnicamente los pacientes con dolor crónico y depresión asociadatuvieron un rendimiento deficitario en pruebas neuropsicológicas,especialmente en tareas que evalúan memoria enlas que la atención juega un papel importante. Por último, losdatos de nuestro estudio revelan que a medida que la intensidaddel episodio depresivo que padece el paciente aumenta,el rendimiento del paciente en dichas pruebas empeora.DiscusiónLas quejas subjetivas de pérdida de memoria que refieren estospacientes parecen guardar relación con el estado de ánimodepresivo que muchos de ellos presentan. Las alteracionesmnésicas parecen explicarse, al menos en parte, por el déficitatencional que padecen(AU)

It is relatively common that patients suffering fromchronic pain complain about memory loss and concentrationproblems. Traditionally, this fact has been connected withthe medication aimed at the management of pain, with thedepressed mood and with pain itself.AimsTo know whether the subjective complaints of memoryloss about which these patients complain can be found in theirperformance in neuropsychological tasks. Secondly, to studywhether there is any difference in such tasks between patientssuffering from chronic pain with depressed mood and thosewithout depressive symptomatology. Finally, to analyze ifthere is a relationship between the severity of the depressivesymptomatology and the performance in neuropsychologicaltasks that assess memory and attention.MethodIn order to fulfil the previous aims, we have carried out atransversal observational study. In this study, 21 patients withchronic pain and subjective complaints of memory loss referredby the Pain Unit of the “Río Hortega” University Hospitaltook part.ResultsOnly those patients suffering from chronic pain and depressedmood performed badly in neuropsychological tasks,especifically in the ones that assess memory in which attentionplays a major role. Finally, the data obtained in our studyrevealed that the more severe the depressive disorder was, themore the performance of the patients in the neuropsychologicaltasks got worse.DiscussionSubjective complaints of memory loss that these patientsstate seem to be related to the depressed mood from whichmany of them suffer. Memory impairment can be explained,at least partially, by the attentional deficit they suffer from(AU)

Characterization of a new plasma membrane-associated ecto-5'-phosphodiesterase/nucleotide-pyrophosphatase from rat hepatocarcinoma AS-30D cells.

We have identified in plasma membrane fractions isolated from rat hepatocarcinoma AS-30D ascites cells three glycoproteins of 125 kDa, 115 kDa and 105 kDa (gp125, gp115 and gp105) which become adenylylated using ATP as substrate, most readily in the presence of EDTA. The gp115 becomes also phosphorylated. The adenylylation of these tumor glycoproteins was much lower than that of a group of analogous adenylylatable glycoproteins (gp130, gp120-gp110 dimer and gp100) present in normal rat liver plasma membrane. The tumor glycoproteins were reversibly O-adenylylated at threonine residues, as was the case for their normal rat liver counterparts. The tumor gp115, and the gp120-gp110 dimer from normal rat liver were both isolated using either ATP-affinity chromatography and/or AMP-affinity chromatography. The gp120-gp110 dimer from normal rat liver was identified as the plasma cell differentiation antigen-1 (PC-1 protein), an ecto-5' phosphodiesterase/ nucleotide-pyrophosphatase (5'-PDE/NPPase). The gp115 from tumor cells also exhibited Zn2+-stimulated 5'-PDE and NPPase activities in alkaline conditions, although it appears to be distinct from the PC-1 protein. We have determined that the gp115 is an ecto-enzyme that catalyzes the hydrolysis of extracellular ATP, since its adenylylation and phosphorylation were detected in intact cells using extracellularly added [alpha-32P]ATP or [gamma-32P]ATP, respectively, in the absence of any permeabilizing agent.

Characterization of a new plasma membrane-associated ecto-5'-phosphodiesterase/nucleotide-pyrophosphatase from rat hepatocarcinoma AS-30D cells.

We have identified in plasma membrane fractions isolated from rat hepatocarcinoma AS-30D ascites cells three glycoproteins of 125 kDa, 115 kDa and 105 kDa (gp125, gp115 and gp105) which become adenylylated using ATP as substrate, most readily in the presence of EDTA. The gp115 becomes also phosphorylated. The adenylylation of these tumor glycoproteins was much lower than that of a group of analogous adenylylatable glycoproteins (gp130, gp120-gp110 dimer and gp100) present in normal rat liver plasma membrane. The tumor glycoproteins were reversibly O-adenylylated at threonine residues, as was the case for their normal rat liver counterparts. The tumor gp115, and the gp120-gp110 dimer from normal rat liver were both isolated using either ATP-affinity chromatography and/or AMP-affinity chromatography. The gp120-gp110 dimer from normal rat liver was identified as the plasma cell differentiation antigen-1 (PC-1 protein), an ecto-5' phosphodiesterase/nucleotide-pyrophosphatase (5'-PDE/NPPase). The gp115 from tumor cells also exhibited Zn2+ stimulated 5'-PDE and NPPase activities in alkaline conditions, although it appears to be distinct from the PC-1 protein. We have determined that the gp115 is an ecto-enzyme that catalyzes the hydrolysis of extracellular ATP, since its adenylylation and phosphorylation were detected in intact cells using extracellularly added [alpha-32P]ATP or [gamma-32P]ATP, respectively, in the absence of any permeabilizing agent.

Advances in the chemistry and pharmacology of ecteinascidins, a promising new class of anti-cancer agents.

Ecteinascidins are marine natural products consisting of two or three linked tetrahydroisoquinoline subunits and an active carbinolamine functional group. Their potent antiproliferative activity against a variety of tumor cells has made them attractive candidates for development as anticancer agents. The lead compound, ecteinascidin 743 (ET 743), is currently in phase II clinical trials but the low amounts present in its natural source, the tunicate Ecteinascidia turbinata, made it necessary to develop efficient synthetic procedures. Recent improvements on the original synthesis are reviewed as well as new strategies starting from readily available cyanosafracin B. ET 743 is known to bind to the minor groove of DNA giving rise to a covalent adduct with the exocyclic amino group at position 2 of a guanine in a fashion similar to saframycin antibiotics. Some of the resulting complexes have been studied by a variety of biochemical and spectroscopic methods and also by computer simulations. The rules for sequence specificity have been well established (preferred targets are RGC and YGG, where R and Y stand for purine and pyrimidine, respectively), and it has been shown that binding of ET 743 to DNA is accompanied by minor groove widening and DNA bending towards the major groove. Although the precise target for antitumor action remains to be unambiguously defined, a role in affecting the transcriptional regulation of some inducible genes is rapidly emerging.

Automated docking and molecular dynamics simulations of nimesulide in the cyclooxygenase active site of human prostaglandin-endoperoxide synthase-2 (COX-2).

Molecular models of the complex between the selective COX-2 inhibitor nimesulide and the cyclooxygenase active site of human prostaglandin-endoperoxide synthase-2 have been built using a combination of homology modelling, conformational searching and automated docking techniques. The stability of the resulting complexes has been assessed by molecular dynamics simulations and interaction energy decomposition. It is found that nimesulide exploits the extra space made available by the replacement at position 523 of an isoleucine residue in COX-1 by a valine in COX-2 and establishes electrostatic interactions with both Arg-106 and Arg-499 (Arg-120 and Arg-513 in PGHS-1 numbering). Two alternate binding modes are proposed which are compatible with the pharmacological profile of this agent as a COX-2 selective inhibitor.

Regulation of cyclooxygenase activity by metamizol.

The ability of metamizol to inhibit cyclooxygenase-1 and cyclooxygenase-2 activities has been evaluated using different cyclooxygenase sources. Metamizol inhibited purified cyclooxygenase-1 and cyclooxygenase-2 with an IC50 of about 150 microg/ml. A similar IC50 value for cyclooxygenase-2 was obtained in lipopolysaccharide-activated broken murine macrophages. Consistent with these findings, molecular models of the complexes between cyclooxygenase-1 or cyclooxygenase-2 with 4-methylaminoantipyrine, the major active derivative of metamizol, suggested a common binding mode to both isoforms. In intact cells, however, the inhibition profiles were markedly different. The IC50 values of metamizol for cyclooxygenase-1 in intact bovine aortic endothelial cells (BAEC) cells and human platelets were 1730 +/- 150 microg/ml and 486 +/- 56 microg/ml, respectively. Inhibition of cyclooxygenase-2 activity in murine macrophages and primary human leukocytes activated by lipopolysaccharide yielded IC50 values of 12 +/- 1.8 microg/ml and 21 +/- 2.9 microg/ml, respectively. These data indicate that the IC50 values obtained with purified enzymes or disrupted cells cannot always be extrapolated to the cyclooxygenase inhibitory activity of nonsteroidal antiinflammatory drugs (NSAIDs) in intact cells. The data presented here also indicate that cyclooxygenase-2 inhibition could play an important role in the pharmacological effects of metamizol.

A method for the purification of phospho(Tyr)calmodulin free of nonphosphorylated calmodulin.

Phosphocalmodulin has been shown to have a differential biological activity compared to nonphosphorylated calmodulin when assayed on a variety of calmodulin-dependent systems. However, the phosphocalmodulin preparations used so far in those experiments were not necessarily free of nonphosphorylated calmodulin. Therefore, the results obtained may not unquestionably show the real effect of pure phosphocalmodulin on the systems under study. To solve this problem, we describe here a method for the purification of phospho(Tyr)calmodulin free of nonphosphorylated calmodulin. The procedure consists of the following steps: (i) phosphorylation of calmodulin by a fraction enriched in epidermal growth factor receptor tyrosine kinase from rat liver isolated by calmodulin affinity chromatography, (ii) isolation of a calmodulin/phosphocalmodulin mixture by Ca(2+)-dependent chromatography in phenyl-Sepharose, (iii) purification of phospho(Tyr)calmodulin using an anti-phosphotyrosine antibody immobilized in agarose upon elution with phenyl phosphate, and (iv) removal of phenyl phosphate from the phospho(Tyr)calmodulin preparation by filtration chromatography in a Bio-Gel P-2 column. The obtained phospho(Tyr)calmodulin preparation was highly pure and essentially free of nonphosphorylated calmodulin because of the use of anti-phosphotyrosine affinity chromatography. We demonstrate that this ultrapure phospho(Tyr)calmodulin preparation is totally incapable of activating the calmodulin-dependent cyclic nucleotide phosphodiesterase. In contrast, when a nonpurified phospho(Tyr)calmodulin preparation was used a partial activation of this enzyme was observed.

Molecular model of the interaction between nimesulide and human cyclooxygenase-2.

The cyclooxygenase-2 (COX-2) isoenzyme is a key target for COX-2-selective non-steroidal anti-inflammatory drugs (NSAIDs). An important difference in binding of nimesulide compared with non-selective NSAIDs appears to involve the amino acid at position 523 of the enzyme. Replacement of valine with isoleucine at this position provides access to a binding site that is larger in COX-2 than in COX-1. Nimesulide appears to exploit this enlarged binding site for establishing a number of favourable contacts with the enzyme that lead to selective inhibition of COX-2. We made these conclusions from a three-dimensional molecular model of the active site of human COX-2, constructed using the X-ray coordinates of COX-1 from sheep seminal vesicles and COX-2 from mouse fibroblasts as templates, with the aid of sequence alignment methods and molecular modelling techniques. The resulting model was refined, and the active site was probed for regions of steric and electrostatic complementarity for ligand binding. Docking studies were then undertaken with many different nimesulide conformers, a family of which could establish very favourable interactions with the NSAID binding site of human COX-2 by exploiting the extra space made available by the isoleucine/valine replacement. The stability of the resulting complexes was studied by simulating molecular dynamics.