Nodal-paranodal antibodies in HIV-immune mediated radiculo-neuropathies: Clinical phenotypes and relevance.

BACKGROUND: The frequency of nodal-paranodal antibodies in HIV-infected patients with chronic immune-mediated radiculo-neuropathies (IMRN) has not been previously described. METHODS: HIV-infected patients who met the inclusion criteria for chronic IMRN were screened for immunoglobulin G (IgG) antibodies directed against nodal (neurofascin (NF)186) and paranodal (NF155, contactin-1 (CNTN1) and contactin-associated protein(Caspr1)) cell adhesion molecules, using a live, cell-based assay. To explore potential pathogenicity, binding of human IgG to myelinated co-cultures was assessed by incubation with patients' sera positive for nodal or paranodal antibodies. Normal human serum was added as a source of complement to assess for complement activation as a mechanism for myelin injury. RESULTS: Twenty-four HIV-infected patients with IMRN were included in the study, 15 with chronic inflammatory demyelinating polyneuropathy (CIDP), 4 with ventral root radiculopathies (VRR), and 5 with dorsal root ganglionopathies (DRG). Five patients with CIDP had combined central and peripheral demyelination (CCPD). Three patients (12.7%) tested positive for neurofascin IgG1 antibodies in the following categories: 1 patient with VRR was NF186 positive, and 2 patients were NF155 positive with DRG and mixed sensory-motor demyelinating neuropathy with optic neuritis, respectively. CONCLUSION: The frequency of nodal-paranodal antibodies is similar among IMRN regardless of HIV status. Interpretation of the results in the context of HIV is challenging as there is uncertainty regarding pathogenicity of the antibodies, especially at low titres. Larger prospective immune studies are required to delineate pathogenicity in the context of HIV, and to establish a panel of antibodies to predict for a particular clinical phenotype.

A note on using a laser-based technique for recording of behaviour and location of free-ranging animals.

We developed a precise, remote (up to 300m) observation system to record animal location and behaviour that requires no animal handling or disruption of the normal environment. Our system, combining a survey laser and a laptop, also allows recording of observed animal behaviour from seconds to hours, with accuracy of 1m or better. Up to one individual per second can be located, which supports data collection of large numbers of animals not possible with other methods. The laser system was used to track a halter-broken heifer led in an arc beginning and ending about 50m from the laser with a maximum distance of about 150m. We recorded the location of the heifer at 35 points along the arc using the laser, a global positioning system (GPS), and a nylon tape. There was an average linear difference of 1.16m (S.D. 0.63) between the laser data and the GPS data. The laser was potentially more accurate than GPS for this application because the laser averaged only 0.21m (S.D. 0.24) linear difference from the tape. Tests of the laser to relocate points in the field to within 0.20m and 0.1 degrees, averaged 0.42m (S.D. 0.29) from the original points. Our technique allows precise location of behaviour and navigation to grazed sites, potentially revealing how animals interact with the resources they exploit and showing the effect of landscape spatial heterogeneity on foraging and habitat use patterns.