Relating the Diers formetric measurements with the subjective severity of acute and chronic low back pain.

BACKGROUND CONTEXT: Nonspecific low back pain (LBP) is a common disorder with a high economic, social and psychological burden. Many systems have been developed for evaluating the severity of LBP, though these are mainly based on scoring questionnaires for the functional status of the patients. Objective quantifiable methods relating LBP with anthropometric factors are scarce. PURPOSE: To find the correlates of nonspecific LBP with spine shape variables and demographic characteristics. To investigate the possible relationship between the latter and the result of a questionnaire subjectively quantifying the severity of LBP. STUDY DESIGN/SETTING: This is a pragmatic observational prospective cohort study. PATIENT SAMPLE: 218 subjects participated in this study. A first group of participants were 160 patients consulting at an osteopathic outpatient clinic for back pain complaints. The second group consisted of 58 healthy pain-free volunteers. OUTCOME MEASURES: The Oswestry Disability Index (ODI) was used to quantify the degree of functional impairment due to low back pain. The surface topography of the back was registered statically with the Diers-4D formetric® system. METHODS: Multivariate analyses of the DIERS 4D formetric system recordings in the subjects with or without nonspecific, acute or chronic LBP. RESULTS: Different patterns between female and male subjects were found. Age, coronal and sagittal imbalance correlated with LBP in female subjects, whereas pelvic inclination, the trunk torsion and apical deviation correlated with LBP in male. Multivariate analyses allowed creating an algorithm to predict the functional disability (predicted LBP-score, PLBP), based on the above variables for females and males. Logistic stepwise regression analysis indicated the probability of a patient having a LBP-score above or below ODI 20 (P= <0.0001), which is considered the clinically relevant threshold value for justifying absence from work. CONCLUSIONS: In this study LBP was correlated with spine shape variables leading to an algorithm predicting the functional disability of a patient due to LBP. Discrepancies between the model and the ODI result may suggest elements that are clinically relevant.

Early postnatal migration and development of layer II pyramidal neurons in the rodent cingulate/retrosplenial cortex.

The cingulate and retrosplenial regions are major components of the dorsomedial (dm) limbic cortex and have been implicated in a range of cognitive functions such as emotion, attention, and spatial memory. While the structure and connectivity of these cortices are well characterized, little is known about their development. Notably, the timing and mode of migration that govern the appropriate positioning of late-born neurons remain unknown. Here, we analyzed migratory events during the early postnatal period from ventricular/subventricular zone (VZ/SVZ) to the cerebral cortex by transducing neuronal precursors in the VZ/SVZ of newborn rats/mice with Tomato/green fluorescent protein-encoding lentivectors. We have identified a pool of postmitotic pyramidal precursors in the dm part of the neonatal VZ/SVZ that migrate into the medial limbic cortex during the first postnatal week. Time-lapse imaging demonstrates that these cells migrate on radial glial fibers by locomotion and display morphological and behavioral changes as they travel through the white matter and enter into the cortical gray matter. In the granular retrosplenial cortex, these cells give rise to a Satb2+ pyramidal subtype and develop dendritic bundles in layer I. Our observations provide the first insight into the patterns and dynamics of cell migration into the medial limbic cortex.

Hunting interactomes of a membrane protein: obtaining the largest set of voltage-dependent anion channel-interacting protein epitopes.

The identification of epitopes involved in protein-protein interactions is essential for understanding protein structure and function. Large scale efforts, although identifying the interactions, did not always yield these epitopes, could not confirm most of the known interactions, and seemed particularly unsuccessful for native intrinsic membrane proteins. We have developed a fluidics-based approach (non-steady-state kinetics) to obtain the broadest set of the epitopes interacting with a given target and applied it to a phage display methodology optimized for membrane proteins. Phages expressing a liver cDNA library were screened against a membrane protein (voltage-dependent anion channel) reconstituted into liposomes and captured on a chip surface. The controlled fluidics was obtained by a surface plasmon resonance (SPR) device that combined the advantages of working with minute reaction volumes and non-equilibrium conditions. We demonstrated selective enrichment of binders and could even select for different binding affinities by fractionation of the selected outputs at various elution times. With voltage-dependent anion channel as bait (a mitochondrial channel critical for cellular metabolism and apoptosis) we found at least 40% of its already reported ligands and independently confirmed 55 novel functional interactions, some of which fully blocked the channel. This highly efficient approach is generally applicable for any protein and could be automated and scaled up even without the use of a SPR device. The epitopes directly identified by this method are useful not only for unraveling interactomes but also for drug design and therapeutics.

Direct measurement of VDAC-actin interaction by surface plasmon resonance.

VDAC--a mitochondrial channel involved in the control of aerobic metabolism and apoptosis--interacts in vitro and in vivo with a wide repertoire of proteins including cytoskeletal elements. A functional interaction between actin and Neurospora crassa VDAC was reported, excluding other VDAC isoforms. From a recent genome-wide screen of the VDAC interactome, we found that human actin is a putative ligand of yeast VDAC. Since such interaction may have broader implications for various mitochondrial processes, we probed it with Surface Plasmon Resonance (SPR) technology using purified yeast VDAC (YVDAC) and rabbit muscle G-actin (RGA). We show that RGA binds to immobilized YVDAC in a reversible and dose-dependent manner with saturating kinetics and an apparent K(D) of 50 microg/ml (1.2 microM actin). BSA does not bind VDAC regardless of the concentrations. Alternatively, VDAC binds similarly to immobilized RGA but without saturating kinetics. VDAC being known to interact with itself, this latter interaction was directly measured to interpret the RGA signals. VDAC could bind to VDAC without saturating kinetics as expected if higher order binding occurred, and could account for maximally 66% of the non-saturating behavior of VDAC binding onto RGA. Hence, actin-VDAC interactions are not a species-specific oddity and may be a more general phenomenon, the role of which ought to be further investigated.

In vitro interactions between the two mitochondrial membrane proteins VDAC and cytochrome c oxidase.

VDAC, a mitochondrial outer membrane channel, is involved in the control of aerobic metabolism and in apoptotic processes via numerous protein-protein interactions. To unveil those interactions, we screened a human liver cDNA library with the phage display methodology optimized to target VDAC reconstituted into a membrane environment. One positively selected clone yielded a sequence matching a part of the subunit I of human cytochrome c oxidase (COX), a mitochondrial inner membrane enzyme. Such putative interaction was never reported before. This interaction proved to be functional as evidenced by the effect of the human and yeast isoforms of VDAC on the oxidation of cytochrome c by the pure holoenzyme and by the effect of the COX epitope on VDAC permeability. Our results providing four independently obtained evidences of VDAC-COX interaction in vitro, would support a novel and potentially important level of mitochondrial regulation given the respective locations and functions of both proteins.

Orientation-dependent gene expression with Epstein-Barr virus-derived vectors.

Episomal vectors, described for efficient and regulated expression of heterologous proteins in mammalian cells, have the advantage that they persist in multiple copies in the cell without integrating into the chromosome. To efficiently express heterologous proteins we used such a vector based on elements of the Epstein-Barr virus (EBV), namely the sequences coding for Epstein-Barr nuclear antigen 1 and the viral origin of replication. Because constitutive expression is often deleterious to the cell, we combined the interferon-inducible Mx promoter with this EBV-derived vector. This resulted in an efficient and strictly regulated expression of the reporter gene chloramphenicol acetyltransferase (CAT) and of the neurotransmitter receptor h5-HT(1B), reaching levels of 16 ng CAT/mg cytoplasmic protein and 1300 fmol receptor/mg membrane protein, respectively. For both proteins, the expression levels were influenced by the orientation of the expression cassette. The higher expression in the favored orientation did not result from a higher copy number of these episomes. Northern analysis revealed a transcriptional read-through from the thymidine kinase promoter on the episomal vector, which interfered with the transcription of the heterologous gene in the less favored orientation.