Design considerations of a randomized clinical trial on a cognitive behavioural intervention using communication and information technologies for managing chronic low back pain

Background

Psychological treatments have been successful in treating chronic low back pain (CLBP). However, the effect sizes are still modest and there is room for improvement. A way to progress is by enhancing treatment adherence and self-management using information and communication technologies (ICTs). Therefore, the objective of this study was to design a trial investigating the short- and long-term efficacy of cognitive behavioural treatment (CBT) for CLBP using or not ICTs. A secondary objective of this trial will be to evaluate the influence of relevant variables on treatment response. Possible barriers in the implementation of CBT with and without ICT will also be investigated.

Methods

A randomised controlled trial with 180 CLBP patients recruited from specialised care will be conducted. Participants will be randomly assigned to three conditions: Control group (CG), CBT, and CBT supported by ICTs (CBT + ICT). Participants belonging to the three conditions will receive a conventional rehabilitation program (back school). The CBT group program will last six sessions. The CBT + ICT group will use the internet and SMS to practice the therapeutic strategies between sessions and in the follow-ups at their homes. Primary outcome variables will be self-reported disability and pain intensity. Assessment will be carried out by blinded assessors in five moments: pre-treatment, post-treatment and 3-, 6-, and 12-month follow-ups. The influence of catastrophizing, fear-avoidance beliefs, anxiety and depression in response to treatment in the primary outcomes will also be analysed.

Discussion

This study will show data of the possible benefits of using ICTs in the improvement of CBT for treating CLBP.

Trial registration

ClinicalTrials.gov, NCT01802671

Characterization of bones by speckle interferometry

Speckle photography interferometry (SPI) is used to evaluate the stress-strain behaviour of animal bones under loads by recording the speckle fields generated on the bone surface and thus finding the relationship between the fractal dimension D(s) and the compression load P. The procedure consists of application of slow and monotonous compression loads, and recording of the deformation levels and vertical displacements of the specimen. A He-Ne laser beam directed at the surface of bone specimen produces light scattering which generates the speckle. The optical fields show significant differences before and after fracture, due to the changes of the bone surface generated by the strain. Our results support previous suggestions of a relationship between fractal characteristics and parameters related to the mechanical behaviour of materials.

Proton and zinc effects on HERG currents

The proton and Zn2+ effects on the human ether-a-go-go related gene (HERG) channels were studied after expression in Xenopus oocytes and stable transfection in the mammalian L929 cell line. Experiments were carried out using the two-electrode voltage clamp at room temperature (oocytes) or the whole-cell patch clamp technique at 35 degrees C (L929 cells). In oocytes, during moderate extracellular acidification (pHo = 6.4), current activation was not shifted on the voltage axis, the time course of current activation was unchanged, but tail current deactivation was dramatically accelerated. At pHo < 6.4, in addition to accelerating deactivation, the time course of activation was slower and the midpoint voltage of current activation was shifted to more positive values. Protons and Zn2+ accelerated the kinetics of deactivation with apparent Kd values about one order of magnitude lower than for tail current inhibition. For protons, the Kd values for the effect on tail current amplitude versus kinetics were, respectively, 1.8 microM (pKa = 5.8) and 0.1 microM (pKa = 7.0). In the presence of Zn2+, the corresponding Kd values were, respectively, 1.2 mM and 169 microM. In L929 cells, acidification to pHo = 6.4 did not shift the midpoint voltage of current activation and had no effect on the time course of current activation. Furthermore, the onset and recovery of inactivation were not affected. However, the acidification significantly accelerated tail current deactivation. We conclude that protons and Zn2+ directly interact with HERG channels and that the interaction results, preferentially, in the regulation of channel deactivation mechanism.

Comparison of lactotrope subtypes of neonatal and adult male rats: plaque assays and patch-clamp studies

We examined the differences in lactotrope number and function between pituitary cultures from neonatal (10-day-old) and adult male rats. Basal hormone release was measured with the reverse hemolytic plaque assay. Whole cell Ba2+ currents through Ca2+ channels were recorded from identified prolactin (PRL) secretors with the patch-clamp technique. Lactotropes were classified in two groups according to the relative amount of PRL released: small-plaque (SP) secretors accounted for 6% of all cells in both neonatal and adult pituitary cultures, whereas large-plaque (LP) secretors comprised 13% of the adult pituitary cells but were scarce in cultures from neonates. Simultaneous plaque assays for PRL and growth hormone (GH) showed that in adults as well as in neonates the number of SP and LP secretors was similar to the number of lactosomatotropes (PRL cells that also release GH) and classical lactotropes (PRL-only cells), respectively. Ba2+ current density at positive membrane potentials was markedly higher in adult LP secretors than in neonatal or adult SP lactotropes. We conclude that the appearance of LP secretors constitutes a major postnatal change within the rat lactotrope population. These cells present a large activity of high-threshold Ca2+ channels in the plasma membrane, release PRL at high basal rates, and may correspond to classical lactotropes. The results further suggest that neonatal lactotrope-like cells persist during development and give place to adult SP secretors.

Lactotrope subtypes are differentially responsive to calcium channel blockers

Pituitary cultures from adult rats contain two subtypes of prolactin (PRL) cells, small-plaque (SP) and large-plaque (LP) lactotropes, which exhibit distinct rates of basal secretion and thereby form PRL plaques of different sizes in reverse hemolytic plaque assay experiments. In the present study, we have used plaque assays to examine the effects of omega-conotoxin (omega-CgTx) and nifedipine, which block Ca2+ entry through high voltage-activated (HVA) channels in the plasma membrane, on basal PRL secretion from single male rat lactotropes. We found that omega-CgTx, like nifedipine, is a potent inhibitor of PRL secretion. In addition, we observed that both drugs decrease the number of cells forming large PRL plaques, while promoting a comparable increase in the abundance of small plaque formers. The results indicate that blocking the HVA Ca channels preferentially suppresses PRL release from LP lactotropes, and suggest that the inhibited PRL secretors tend to behave functionally as SP lactotropes.

[Hemodynamic effects of dobutamine in critical patients: discrepancies between parameters of tissue oxygenation and lactic acid]

A retrospective study on the effects of dobutamine on hemodynamic parameters of tissue oxygenation and lactic acid levels was performed in 35 patients. The use of the drug in a mean dose of 5.0 +/- 2.1 ug/kg/min was associated with a significant increase in cardiac index, oxygen transport and consumption and decrease in arterial lactic acid levels. A separate analysis of patients with or without basal hyperlactacidemia and those with favorable (decrease) or unfavorable (no change or increase) lactic acid response to the drug, was performed. This analysis disclosed important disagreements between changes in hemodynamic parameters of oxygen consumption and transport and arterial lactic acid levels, as indexes of tissue perfusion. It is concluded that is advisable to monitor together hemodynamics, oxygen transport and consumption and arterial lactic acid in patients with severe cardiorespiratory disturbances or shock.

Differential expression of Na channels in functional subpopulations of rat lactotropes

We have investigated the voltage-dependent Na channel activity of single lactotropes in pituitary cultures from adult male rats by recording whole cell Na+ currents under voltage clamp. Cells were identified by their ability to secrete prolactin in the basal state as measured with the reverse hemolytic plaque assay. We found that cells with elevated secretory rates [large-plaque (LP) lactotropes] present relatively large Na+ currents in response to depolarization, whereas Na+ currents in cells secreting prolactin at low rates [small-plaque (SP) lactotropes] are small or are not detectable. The maximum amplitude of the inward Na+ current, normalized by cell capacitance, is about sixfold larger, on the average, in LP lactotropes than in SP lactotropes. Complete block of the Na channels with external tetrodotoxin inhibits by approximately 72% the amount of prolactin secreted from the entire cell population over a period of 1 h, an effect that depends on a drastic reduction in the proportion of LP lactotropes. The results indicate that Na channel activity promotes basal prolactin secretion in male rat lactotropes and suggest that differences in Na channel expression contribute to explain the functional heterogeneity of these pituitary cells.

Calcium channels and basal prolactin secretion in single male rat lactotropes

Ba2+ currents through voltage-dependent Ca channels and basal prolactin secretion were measured in single, cultured lactotropes by the combined use of whole cell patch-clamp recording and the reverse hemolytic plaque assay. Measurements of plaque area, a cumulative index of the relative amount of prolactin released by a cell per unit time, indicate that lactotropes can be grouped in two main subpopulations that differ in basal secretory activity: small-plaque (SP) cells and large-plaque (LP) cells. Analysis of Ba2+ currents indicates that both SP and LP lactotropes express two types of Ca channels: low-threshold, inactivating, slowly deactivating (SD) channels and high-threshold, noninactivating, fast deactivating (FD) channels. Ba2+ current amplitude is smaller in SP cells than in LP cells. Plaque area, and thus prolactin release, is positively correlated with the density of Ba2+ current through FD channels, but not with that through SD channels. The results suggest that the surface density of functional FD Ca channels in the plasma membrane is a major factor that determines the rate of basal prolactin secretion in single lactotropes.