Ca(2+) binding protein S100A1 competes with calmodulin and PIP2 for binding site on the C-terminus of the TPRV1 receptor.

Transient receptor potential vanilloid 1 ion channel (TRPV1) belongs to the TRP family of ion channels. These channels play a role in many important biological processes such as thermosensation and pain transduction. The TRPV1 channel was reported to be also involved in nociception. Ca(2+) ions are described to participate in the regulation of TRP channels through the interaction with Ca(2+)-binding proteins, such as calmodulin or S100A1. Calmodulin is involved in the Ca(2+)-dependent regulation of TRPV1 via its binding to the TRPV1 C-terminal region. However, the role of the Ca(2+)-binding protein S100A1 in the process of TRP channel regulation remains elusive. Here we characterized a region on the TRPV1 C-terminus responsible for the interaction with S100A1 using biochemical and biophysical tools. We found that this region overlaps with previously identified calmodulin and PIP2 binding sites and that S100A1 competes with calmodulin and PIP2 for this binding site. We identified several positively charged residues within this region, which have crucial impact on S100A1 binding, and we show that the reported S100A1-TRPV1 interaction is calcium-dependent. Taken together, our data suggest a mechanism for the mutual regulation of PIP2 and the Ca(2+)-binding proteins S100A1 and calmodulin to TRPV1.

Changes caused by haloperidol are blocked by music in Wistar rat

This study sought to evaluate the effect of classical music, using Mozart’s sonata for two pianos (K. 448), on changes in dopamine (DA) levels in the striatal nucleus (SN), prefrontal cortex (PFC) and mesencephalon, and on prolactin (PRL) and corticosterone secretion in adult male Wistar rats. Rats were divided into four groups: (1) control, (2) haloperidol treatment (single dose of 2 mg/kg s.c.), (3) music (two 2-h sessions per day) and (4) haloperidol plus music. Rats were sacrificed 2 h after haloperidol injection. Music prompted a fall in plasma PRL and corticosterone levels in healthy rats (P < 0.05) and prevented the increase in levels triggered by haloperidol (P < 0.001). Moreover, exposure to music was associated with a significant increase in DA levels in all groups, with the increase being particularly marked in PFC and SN (P < 0.001). Haloperidol is a recognised D2 receptor antagonist, and these findings suggest that music, by contrast, enhances DA activity and turnover in the brain. The results obtained here bear out reports that music triggers a reduction in systolic pressure and an increase in mesencephalon dopamine levels in human and rats treated with ecstasy, through a calmodulin-dependent system (AU)

Actuación de enfermería relacionada con pacientes en diálisis peritoneal y tratamiento con Cinacalcet / Nursing action related to patients on peritoneal dialysis and treatment with cinacalcet

El hiperparatiroidismo secundario a IRCT es una complicación frecuente y se asocia a un elevado índice de morbilidad en pacientes en programa de diálisis. Una vez se ha establecido, se debe intentar frenar su desarrollo, manteniendo una adecuada mineralización ósea y protegiendo de calcificaciones vasculares. Este último efecto aumenta el riesgo cardiovascular, y favorece amputaciones e incluso la muerte. Para esto se cuenta con recomendaciones dietéticas y diversos tratamientos farmacológicos. En el año 2004, aparece el cinacalcet (Mimpara®), que se engloba dentro del grupo de los calcimiméticos, y que ha sido aprobado en España, en 2005. Con el fin de conocer su efectividad se ha realizado el seguimiento de cinco pacientes en programa de Diálisis Peritoneal con hiperpartiroidismo, rebeldes al tratamiento conservador y que iniciaron tratamiento con Mimpara® con el fin de conocer su efectividad. Se ha diseñado un protocolo de actuación de enfermería que permitió monitorizar todas las actividades. Los resultados analíticos han mejorado en todos los casos notablemente. Los síntomas que referían los pacientes previos al tratamiento, han desaparecido tras iniciarlo y además no destaca ningún efecto secundario adverso. Es importante reseñar que este es un estudio a corto plazo con una muestra pequeña, por lo que sería interesante seguir trabajando en el mismo. El control estrecho por parte de enfermería favorece la adhesión al tratamiento y el seguimiento de la dieta, lo cual refleja una satisfacción en dichos pacientes (AU)

Secondary hyperparathyroidism in TCRI is a frequent complication and is associated to a high morbidity index in patients on dialysis programmes. Once it has been established, attempts should be made to slow down its development, maintaining adequate bone mineralization and protecting from vascular calcification. This last effect increases the cardiovascular risk, and the risk of amputations and even death. For this reason, there are diet recommendations and several pharmacological treatments. In 2004, Cinacalcet (Mimpara®) appeared, which belongs to the group of calcimimetics, and was approved in Spain in 2005. In order to determine its effectiveness, five patients on peritoneal dialysis and with hyperparathyroidism were monitored, who had not responded to conservative treatment and commenced treatment with Mimpara® in order to determine its effectiveness. A protocol has been designed for nursing attention that lets all the activities be monitored. The analytical results improved notably in all cases. The symptoms referred by patients prior to treatment disappeared after commencing treatment and no adverse side effects were noted. It is important to note that this is a short-term study with a small sample, and therefore it would be interesting to continue working on it. Close control by nursing staff favours adherence to the treatment and the diet, which reflects satisfaction in the patients in question (AU)

Positive regulation of GABA(B) receptors dually coupled to cyclic AMP by the allosteric agent CGP7930.

The ability of 2,6 Di-tert-butyl-4-(-hydroxy-2,2-dimethyl-propyl)-phenol (CGP7930), a positive allosteric modulator of GABA(B) receptors, to regulate GABA(B) receptor-induced stimulation and inhibition of adenylyl cyclase activity in rat brain was investigated. In olfactory bulb granule cell layer and in frontal cortex, CGP7930 potentiated the stimulatory effects of (-)-baclofen and gamma-aminobutyric acid (GABA) on basal and corticotropin-releasing hormone-stimulated adenylyl cyclase activities, respectively. In these stimulatory responses, CGP7930 enhanced both agonist potencies and maximal effects. When GABA(B) receptor-mediated inhibition of forskolin-stimulated adenylyl cyclase activity of frontal cortex was examined, CGP7930 increased the agonist potencies but failed to affect the maximal effect of (-)-baclofen and modestly increased that of GABA. Similar results were obtained for the inhibition of Ca(2+)/calmodulin-stimulated adenylyl cyclase in striatum and cerebellum. Western blot analysis of each membrane preparation showed the presence of GABA(B2) receptor subunit, a putative site of action of CGP7930. These data indicate that CGP7930 positively modulates brain GABA(B) receptors coupled to either stimulation or inhibition of cyclic AMP signalling.

[Intracellular calcium homeostasis. Calmodulin and Ca(2+)-ATPase of the plasma membrane of Trypanosomatids]. / Homeostasis intracelular del calcio. La calmodulina y la Ca(2+)-ATPasa de la membrana plasmatica de tripanosomatidios.

The intracellular Ca2+ concentration in all eukaryotic cells so far studied is 4 orders of magnitude lower than in the extracellular milieu. In trypanosomatids, the intracellular concentration of this cation is around 50 nM, even lower than in higher eukaryotics. This differential concentration is maintained by diverse transport systems at the plasma membrane level and at certain intracellular organelles. In the case of trypanosomatids it have been identified the presence of an electrophoretic uniporter at the internal membrane of the unique giant mitochondrion of these parasites, showing identical kinetics properties to the homologous system of higher eukaryotics. Thus, the low Ca2+ affinity of this system is not compatible with its putative function of maintaining intracellular Ca2+ at the submicromolar level. Contrary to previous reports, we have identified a Ca(2+)-ATPase in the plasma membrane of Leishmania braziliensis, Leishmania mexicana, Trypanosoma cruzi and Trypanosoma brucei. The enzyme possesses a high Ca2+ affinity (Km Ca2+ = 0.5 microM), is Mg(2+)-dependent and activatable by calmodulin purified from these hemoflagellates. The Ca(2+)-ATPase is sensitive to vanadate (Ki = 1 microM), thus typifying it as a "P" type ion pump. Vesicles from the plasma membrane of these parasites are able to accumulate Ca2+ against a concentration gradient. The kinetic properties of both transport and ATPase are essentially the same, thus suggesting the same molecular entity. The above results strongly suggest that the Ca(2+)-ATPase is the mechanism responsible for the long-term fine-tuning of intracellular Ca2+ at the submicromolar lever in trypanosomatids.

Increased slow transport in axons of regenerating newt limbs after a nerve conditioning lesion.

We have previously shown that a nerve conditioning lesion (CL) made 2 weeks prior to amputation results in an earlier onset of limb regeneration in newts. Studies in fish and mammals demonstrate that when a CL precedes a nerve testing lesion, slow component b (SCb) of axonal transport is increased compared to axons that had not received a CL. We wanted to know whether the earlier initiation of limb regeneration after a CL was associated with an increase in SCb transport. The transport of [35S]methionine labeled SCb proteins was measured by using SDS-PAGE, fluorography, and scintillation counting. The rate of transport and quantity of SCb proteins was determined at 7, 14, 21, and 28 days after injection of [35S]methionine into the motor columns of normal; single lesioned (i.e., transection axotomy, amputation axotomy, or sham CL followed by amputation); and double-lesioned limb axons (i.e., nerve transection CL followed 2 weeks later by amputation axotomy). The rate of SCb transport in axons of unamputated newt limbs was 0.19 mm/day. There was an increase in the amount of labeled SCb proteins transported in axons regenerating as the result of a single lesion but no acceleration in the rate of SCb transport, which was 0.21 mm/day in axons that received a sham CL followed by limb amputation. The rate of SCb transport doubled (0.40 mm/day) and the amount of labeled SCb proteins being transported was increased when amputation was preceded by a CL. This study demonstrates that the earlier onset of limb regrowth, seen when amputation follows a CL, is associated with an increased transport of SCb proteins. This suggests that limb regeneration is, in part, regulated by axonal regrowth. We propose that the blastema requires a minimum quantity of innervation before progressing to the next stage of limb regeneration, and that the transport of SCb proteins determines when that quantity will be available.

Isolation and characterization of bovine mammary calmodulin.

Bovine mammary gland calmodulin, purified by conventional fractionation procedures, was compared with similarly purified bovine brain calmodulin. Affinity chromatography on W-7 agarose of the crude fractions from mammary gland and brain yielded pure proteins containing one trimethyllysine residue per 16,800 daltons with essentially identical amino acid compositions. Kinetic parameters of these two proteins with respect to their ability to activate phosphodiesterase were determined. The constants for half maximum activation were .39 and .44 nM for bovine brain and bovine mammary gland calmodulins, respectively; both proteins gave similar maximum velocities. Based on the amino acid composition and kinetic data, it is concluded that the two proteins are essentially identical.