Biomedical subjects

Francis A Billson

Publications and source records attributed to Francis A Billson.

5 recordsLinked to original sources

PubMed2006

Multifocal visual evoked potential analysis of inflammatory or demyelinating optic neuritis.

OBJECTIVE: To determine the sensitivity of multifocal visual evoked potentials (mVEP) in optic neuritis of an inflammatory or demyelinating nature. DESIGN: Cross-sectional study. PARTICIPANTS: Sixty-four patients participated who had a confirmed diagnosis of optic neuritis (ON) (past and acute). Based on the McDonald multiple sclerosis (MS) criteria, 25 patients (27 eyes with ON) were deemed to have isolated optic neuritis and thus not have MS (i.e., the not-MS group), and 19 patients (24 eyes with ON) had a diagnosis of MS (i.e., the MS group). The remaining 20 patients (25 eyes with ON) were at a high risk of MS, but diagnostic evaluation was equivocal, and thus were classified as the possible MS group. A control group of 20 normal patients was enrolled. TESTING: The mVEP test was performed using the Accumap. All ON patients had recent magnetic resonance imaging scans of the brain and spinal cord. MAIN OUTCOME MEASURES: Multifocal visual evoked potentials amplitude and latency values were analyzed within each group and were compared with the normal controls. RESULTS: No abnormality was recorded on mVEP in the control group. Of all the ON eyes, 74 (97.3%) were abnormal on mVEP testing. Amplitude values were abnormal in 92.6% of not-MS eyes, 92.0% of possible MS eyes, and 100% of those with MS, and latency was abnormal in 33.3%, 76.0%, and 100%, respectively. There was a significant difference in the mVEP latency z-scores among all ON groups (P<0.01; Kruskal-Wallis test). Although distribution graphs of latency z-scores in the not-MS and MS groups had single peaks and were clearly separate from each other, the latency z-score distribution within the possible MS group in postacute patients was bimodal, with each peak corresponding to the distribution of the not-MS and MS group, respectively. The mVEP latency z-scores had a sensitivity and specificity of 100% in detecting patients with ON due to MS when compared with normal patients. CONCLUSIONS: The mVEP test is a sensitive and specific tool for detecting optic neuritis. There was a significant difference in latency analysis findings between patient groups as classified according to the McDonald MS criteria. Latency results suggest a role in identifying a patient's risk for future MS.

Acute Disease↗

PubMed2005

In vitro targeting of NG2 antigen by 213Bi-9.2.27 alpha-immunoconjugate induces cytotoxicity in human uveal melanoma cells.

PURPOSE: To examine uveal melanoma cell lines for the expression of human melanoma proteoglycan (NG2) using monoclonal antibody (mAb) 9.2.27 and subsequently to assess the in vitro specificity and cytotoxicity of mAb 9.2.27 conjugated to the alpha-particle-emitting radioisotope 213bismuth (213Bi-9.2.27) for uveal melanoma cells. METHODS: Immunocytochemistry and flow cytometry were used to examine OCM-1, OCM-3, OCM-8, OMM-1, Mel202 and 92-1 melanoma cell lines for NG2 expression. Melanoma cells were treated with test (213Bi-9.2.27) or control (213Bi-A2) alpha-immunoconjugates (AICs). The specific cytotoxicity of 213Bi-9.2.27 AIC was evaluated using an MTS (3-(4,5-dimethylthiazol-2-yl)-5-(3-carboxymethoxyphenyl)-2-(4-sulfenyl)-2H-tetrazolium, inner salt) assay. Cell death was also assessed using TUNEL. RESULTS: OCM-1, OCM-8, OMM-1, and Mel202 cells strongly expressed NG2. OCM-3 cells showed moderate expression and 92-1 cells were NG2-negative. 213Bi-9.2.27 specifically killed NG2-positive OCM-1, OCM-8, and OMM-1 cells in a concentration-dependent manner. D0 values for 37% cell survival of NG2-positive OCM-1, OCM-8, and OMM-1 cells were 5.8, 5.0, and 5.6 microCi, respectively, and the value was 43.4 muCi for NG2-negative 92-1 cells. CONCLUSIONS: The specific cytotoxicity of 213Bi-9.2.27 AIC for NG2-positive, but not NG2-negative, cells suggests NG2 is a suitable target for alpha-immunotherapy in uveal melanoma. 213Bi-9.2.27 AIC used directly or as adjunct therapy may be a promising new agent for treating NG2-positive uveal melanomas or metastases.

Antibodies, Bispecific↗

PubMed2003

Effect of pupil size on multifocal pattern visual evoked potentials.

The purpose of this study was to investigate the influence of pupil diameter on the amplitude and latency of multifocal visual evoked potentials (mfVEP). The multifocal objective perimeter (Accumap; Objectivision) was used to stimulate the visual field at 56 sites extending to 32 degrees using a pseudo-random pattern stimulus. The mfVEP were recorded using bipolar occipital electrodes, 7 min/eye. Ten normal subjects were recruited from the community and one eye was randomly selected for testing. The mfVEP were recorded at four different pupil diameters (2 mm, 4 mm, 6 mm, 8 mm), obtained by applying tropicamide (0.5%) or pilocarpine (2%) in different dilutions. Appropriate refractive correction was provided to overcome cycloplegia and achieve a visual acuity of 6/7.5 or better. Analysis revealed that at most pupil diameters the normalized full field amplitude did not show significant variation, except at the most miotic pupil diameter (2 mm), where the amplitude became reduced, based on 2-way anova and Tukey's T method. There was, however, significant correlation between latency and pupil area (correlation coefficient: upper field -0.63, lower field -0.76). The results suggest that even in the presence of mydriatics or miotics, the mfVEP test can be used to assess diseases that affect amplitude, provided near correction is used. The interpretation of latency, however, must be made with caution, as a borderline conduction defect with a dilated pupil may appear normal.

Adult↗

PubMed2002

Effects of post-mortem delay and storage duration on the expression of GFAP in normal human adult retinae.

Glial fibrillary acidic protein (GFAP) is an established marker of retinal glia and has been shown to be modulated by several cytokines and retinal pathology. The influence of a number of factors, including post-mortem delay, storage duration and retinal pathology, on the distribution and morphology of macroglia and GFAP antigenicity was examined in human retina. The effects of these parameters on GFAP expression were estimated using immunohistochemistry, confocal microscopy and image analysis. Changes in expression of antigenicity were analysed in human retinal cryosections at three levels: constitutive,aberrant and total. The results indicated that short-term and long-term storage duration had no significant effect on GFAP immunoreactivity at all three levels of expression (P > 0.2).However, a significant increase in GFAP immunoreactivity and distribution at all three levels of expression was associated with prolonged post-mortem delay (> 30 h) (P < 0.05). This study highlights the importance of rigorous matching of post-mortem delay between control specimens in histological studies of human retinae. The study further demonstrates the utility of Eye Bank retinae fixed and stored in 2% paraformaldehyde, provided that appropriate controls are applied.

Adult↗

PubMed2002

Immunoglobulin superfamily expression in primary retinoblastoma and retinoblastoma cell lines.

Retinoblastoma (Rb) is the most common intraocular tumor of childhood. In this study we examined primary Rb specimens and Rb cell lines for the expression of immunoglobulin superfamily (IgSF) antigens: MHC class I and II (MHC-I and MHC-II), neural cell adhesion molecule (NCAM), intercellular adhesion molecule-1 (ICAM-1), and Thy-1, which play an important role in immune system and tumor cell interactions. MHC-I and-II, ICAM-1 (CD54), NCAM (CD56), and Thy-1 (CDw90) immunoreactivity was studied in eight primary Rb biopsy specimens using immunohistochemistry, three using immunoelectron microscopy, and six Rb cell lines using flow cytometry (FCM). Parenchymal and vascular-associated cells, phenotypically similar to retinal microglia, strongly expressed MHC-II immunoreactivity and were distributed throughout primary Rb specimens. However, MHC-II expression on Rb cell lines was similar to nonspecific control levels. Tumor cells in primary Rb specimens displayed high NCAM, moderate Thy-1, and low MHC-I and ICAM-1 immunolabeling. Tumor vasculature expressed low to moderate MHC-I and ICAM-1 immunoreactivity and moderate Thy-1 immunoreactivity. NCAM was not detected on the vasculature of primary Rb specimens. Rb cell lines displayed variable expression of Thy-1, ICAM-1, and MHC-I. NCAM was highly expressed on five of six Rb cell lines. The high levels of constitutive NCAM immunoreactivity on Rb tumor cells confirm the neuroectodermal origins of this tumor. Additionally, the variable expression of Thy-1 may suggest separate neural lineages or differences in the maturational status ofsome Rb tumors. The presence of a population of infiltrating MHC-II-positive cells in primary Rb tumors has implications for immunomodulation of Rb growth.

Child, Preschool↗