Locomotor Dysfunction and Pain: The Scylla and Charybdis of Fiber Sprouting After Spinal Cord Injury

Injury to the spinal cord (SCI) can produce a constellation of problems including chronic pain, autonomic dysreflexia, and motor dysfunction. Neuroplasticity in the form of fiber sprouting or the lack thereof is an important phenomenon that can contribute to the deleterious effects of SCI. Aberrant sprouting of primary afferent fibers and synaptogenesis within incorrect dorsal horn laminae leads to the development and maintenance of chronic pain as well as autonomic dysreflexia. At the same time, interruption of connections between supraspinal motor control centers and spinal cord output cells, due to lack of successful regenerative sprouting of injured descending fiber tracts, contributes to motor deficits. Similarities in the molecular control of axonal growth of motor and sensory fibers have made the development of cogent therapies difficult. In this study, we discuss recent findings related to the degradation of inhibitory barriers and promotion of sprouting of motor fibers as a strategy for the restoration of motor function and note that this may induce primary afferent fiber sprouting that can contribute to chronic pain. We highlight the importance of careful attentiveness to off-target molecular- and circuit-level modulation of nociceptive processing while moving forward with the development of therapies that will restore motor function after SCI.     

Dutch observation scales to assess cognitive abilities of the aged

Assessment of complex geriatric health problems by nurses is important for diagnosis, especially assessment of cognitive functioning through daily observations. However, it is unclear which Dutch observation scales are available to assess cognitive abilities. In this study, we present an overview of these scales. A systematic review was performed. Beforehand we determined criteria for inclusion of scales and we searched through Dutch and English databases up till May 2005. Thirteen behavioural observation scales were found. The number of dimensions of cognitive functioning assessed in the scales varied greatly, from two to eight in number. Memory and psychomotor behaviour were always included; consciousness and thinking were frequently included, while alertness, perception, executive functions and language were least included. Extensive assessment of cognitive functioning is highly relevant for a geriatric hospital ward in which patients are admitted for diagnosis. Of all scales that we traced, the A-one is the most extensive: all eight dimensions are included. Little is known about the potential for using the A-one scale in nursing practice; further exploration is indicated. For now, nurses should become acquainted with the different dimensions of cognitive functioning and start to integrate observations in these dimensions in their reporting.     

Histochemical analysis of insulin-like growth factor-1 binding sites in mouse normal and expermmentally induced arthritic articular cartilage

Summary Insulin-like growth factor-1 (IGF-1) plays a key role in regulation of chondrocyte metabolism. We examined the localization of IGF-1 binding sites on chondrocytes in cartilage from normal and experimentally induced arthritic mouse knee joints. Cryostat sections from patellar cartilage were incubated either with IGF-1 receptor antibody or biotinylated IGF-1. Subsequently confocal laser scanning microscopy was applied to compare the two staining procedures qualitatively and quantitatively. This approach allowed detailed analysis of membrane-associated and intracellular staining. Using IGF-1 receptor antibody, IGF-1 receptors were found on the cell membrane of chondrocytes in the middle and deeper cartilage zones, whereas intracellular staining was highest in chondrocytes of superficial zones. After incubation with biotinylated IGF-1, distinct membrane staining was not present and fluorescence was localized homogeneously in themiddle and deeper zones but not in superficial zones. In cartilage from inflamed knee joints staining with the use of IGF-1 receptor antibody did not change significantly, whereas a pronounced increase in staining was noted with biotinylated IGF-1 in chondrocytes of the middle and deeper zones of cartilage. It is concluded that the staining patterns obtained with the use of IGF-1 receptor antibody and biotinylated IGF-1 are remarkably different, suggesting that the latter also detects IGF-binding proteins. The results suggest that joint inflammation has no consistent effect on IGF-1 receptor expression but may induce a significant upregulation of IGF-binding proteins in chondrocytes of the middle and deeper zones of cartilage.     

Red light imaging for programmed cell death visualization and quantification in plant–pathogen interactions

Studies on plant–pathogen interactions often involve monitoring disease symptoms or responses of the host plant to pathogen-derived immunogenic patterns, either visually or by staining the plant tissue. Both these methods have limitations with respect to resolution, reproducibility, and the ability to quantify the results. In this study we show that red light detection by the red fluorescent protein (RFP) channel of a multipurpose fluorescence imaging system that is probably available in many laboratories can be used to visualize plant tissue undergoing cell death. Red light emission is the result of chlorophyll fluorescence on thylakoid membrane disassembly during the development of a programmed cell death process. The activation of programmed cell death can occur during either a hypersensitive response to a biotrophic pathogen or an apoptotic cell death triggered by a necrotrophic pathogen. Quantifying the intensity of the red light signal enables the magnitude of programmed cell death to be evaluated and provides a readout of the plant immune response in a faster, safer, and nondestructive manner when compared to previously developed chemical staining methodologies. This application can be implemented to screen for differences in symptom severity in plant–pathogen interactions, and to visualize and quantify in a more sensitive and objective manner the intensity of the plant response on perception of a given immunological pattern. We illustrate the utility and versatility of the method using diverse immunogenic patterns and pathogens.     

Plasma proteome analysis in HTLV-1-associated myelopathy/tropical spastic paraparesis

Background

A new subgroup of HIV-1, designated Group P, was recently detected in two unrelated patients of Cameroonian origin. HIV-1 Group P phylogenetically clusters with SIVgor suggesting that it is the result of a cross-species transmission from gorillas. Until today, HIV-1 Group P has only been detected in two patients, and its degree of adaptation to the human host is largely unknown. Previous data have shown that pandemic HIV-1 Group M, but not non-pandemic Group O or rare Group N viruses, efficiently antagonize the human orthologue of the restriction factor tetherin (BST-2, HM1.24, CD317) suggesting that primate lentiviruses may have to gain anti-tetherin activity for efficient spread in the human population. Thus far, three SIV/HIV gene products (vpu, nef and env) are known to have the potential to counteract primate tetherin proteins, often in a species-specific manner. Here, we examined how long Group P may have been circulating in humans and determined its capability to antagonize human tetherin as an indicator of adaptation to humans.

Results

Our data suggest that HIV-1 Group P entered the human population between 1845 and 1989. Vpu, Env and Nef proteins from both Group P viruses failed to counteract human or gorilla tetherin to promote efficient release of HIV-1 virions, although both Group P Nef proteins moderately downmodulated gorilla tetherin from the cell surface. Notably, Vpu, Env and Nef alleles from the two HIV-1 P strains were all able to reduce CD4 cell surface expression.

Conclusions

Our analyses of the two reported HIV-1 Group P viruses suggest that zoonosis occurred in the last 170 years and further support that pandemic HIV-1 Group M strains are better adapted to humans than non-pandemic or rare Group O, N and P viruses. The inability to antagonize human tetherin may potentially explain the limited spread of HIV-1 Group P in the human population.     

Chaperones of the endoplasmic reticulum are required for Ve1‐mediated resistance to Verticillium

The tomato receptor‐like protein (RLP) Ve1 mediates resistance to the vascular fungal pathogen Verticillium dahliae. To identify the proteins required for Ve1 function, we transiently expressed and immunopurified functional Ve1‐enhanced green fluorescent protein (eGFP) from Nicotiana benthamiana leaves, followed by mass spectrometry. This resulted in the identification of peptides originating from the endoplasmic reticulum (ER)‐resident chaperones HSP70 binding proteins (BiPs) and a lectin‐type calreticulin (CRT). Knock‐down of the different BiPs and CRTs in tomato resulted in compromised Ve1‐mediated resistance to V. dahliae in most cases, showing that these chaperones play an important role in Ve1 functionality. Recently, it has been shown that one particular CRT is required for the biogenesis of the RLP‐type Cladosporium fulvum resistance protein Cf‐4 of tomato, as silencing of CRT3a resulted in a reduced pool of complex glycosylated Cf‐4 protein. In contrast, knock‐down of the various CRTs in N. benthamiana or N. tabacum did not result in reduced accumulation of mature complex glycosylated Ve1 protein. Together, this study shows that the BiP and CRT ER chaperones differentially contribute to Cf‐4‐ and Ve1‐mediated immunity.     

SOBIR1 requires the GxxxG dimerization motif in its transmembrane domain to form constitutive complexes with receptor‐like proteins

Receptor‐like proteins (RLPs), forming an important group of transmembrane receptors in plants, play roles in development and immunity. RLPs contain extracellular leucine‐rich repeats (LRRs) and, in contrast with receptor‐like kinases (RLKs), lack a cytoplasmic kinase required for the initiation of downstream signalling. Recent studies have revealed that the RLK SOBIR1/EVR (SUPPRESSOR OF BIR1‐1/EVERSHED) specifically interacts with RLPs. SOBIR1 stabilizes RLPs and is required for their function. However, the mechanism by which SOBIR1 associates with RLPs and regulates RLP function remains unknown. The Cf immune receptors of tomato (Solanum lycopersicum), mediating resistance to the fungus Cladosporium fulvum, are RLPs that also interact with SOBIR1. Here, we show that both the LRR and kinase domain of SOBIR1 are dispensable for association with the RLP Cf‐4, whereas the highly conserved GxxxGxxxG motif present in the transmembrane domain of SOBIR1 is essential for its interaction with Cf‐4 and additional RLPs. Complementation assays in Nicotiana benthamiana, in which endogenous SOBIR1 levels were knocked down by virus‐induced gene silencing, showed that the LRR domain as well as the kinase activity of SOBIR1 are required for the Cf‐4/Avr4‐triggered hypersensitive response (HR). In contrast, the LRRs and kinase activity of SOBIR1 are not required for facilitation of Cf‐4 accumulation. Together, these results suggest that, in addition to being a stabilizing scaffold for RLPs, SOBIR1 is also required for the initiation of downstream signalling through its kinase domain.