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Biomedical subjects

B Chopra

Publications and source records attributed to B Chopra.

7 recordsLinked to original sources
PubMed2002

CSF beta-1 Globulin--a potential marker in differentiating multiple sclerosis and acute disseminated encephalomyelitis: a preliminary study.

The exact diagnosis of demyelinating diseases is an enigma even in the best neurological centres. In the present study, the potential role of differential CSF proteins has been critically evaluated in differentiating multiple sclerosis (MS) and acute disseminated encephalomyelitis (ADEM). Cellulose acetate electrophoresis was carried out on CSF and serum samples of 14 MS patients, 23 ADEM patients and 30 controls. There was no statistically significant difference between serum electrophoresis of controls and MS patients. However, in case of CSF electrophoresis there was a statistically significant decrease in beta-1 fraction in 92.2% of MS patients (p=0.01). A comparison between serum electrophoresis of controls and ADEM patients indicated a statistically significant decrease in serum albumin in 87% patients and an increase of alpha-2 globulin in 73.9%. There was no statistically significant difference between CSF electrophoresis of controls and ADEM patients except for the prealbumin fraction which was raised in 60.9% of patients. No statistically significant difference was seen between the serum electrophoresis of ADEM and MS patients. However, on comparing CSF electrophoresis, it was seen that beta-1 fraction was significantly higher in ADEM patients (p<0.05). The predictive value of beta-1 fraction in differentiating MS and ADEM was then evaluated. The negative predictive value was 100% indicating that all samples with a beta-1 fraction of>6.5% cannot be diagnosed as MS. The significant decrease in beta-1 fraction in MS patients may prove to be an early indicator in differentiating between MS and ADEM patients.

Biomarkers↗
PubMed2000

Characterization of the binding of two novel glycine site antagonists to cloned NMDA receptors: evidence for two pharmacological classes of antagonists.

The potency of two novel glycine site antagonists, GV150,526A and GV196,771A, was assessed by their ability to inhibit the binding of [(3)H]-MDL105,519 to cell homogenates prepared from mammalian cells transfected with either NR1-1a, NR1-2a, NR1-1a/NR2A, NR1-1a/NR2B, NR1-1a/NR2C or NR1-1a/NR2D NMDA receptor clones. The inhibition constants (K(i)s) for GV150,526A displacement of [(3)H]-MDL105,519 binding to either NR1-1a or NR1-2a expressed alone were not significantly different and were best fit by a one-site binding model. GV150,526A inhibition to NR1-1a/NR2 combinations was best fit by a two-site model with the NR1-1a/NR2C having an approximate 2 - 4 fold lower affinity compared to other NR1-1a/NR2 receptors. The K(i)s for GV196,771A displacement of [(3)H]-MDL105,519 binding to NR1-1a, NR1-2a and all NR1-1a/NR2 combinations was best fit by a two-site binding model. There was no significant difference between the K(i)s for the binding to NR1-1a and NR1-2a; NR1-1a/NR2A receptors had an approximate 4 fold lower affinity for GV196,771A compared to other NR1-1a/NR2 combinations. The K(i)s for both GV150, 526A and GV196,771A for the inhibition of [(3)H]-MDL105,519 binding to membranes prepared from adult rat forebrain were determined and compared to the values obtained for binding to cloned NMDA receptors. The K(i)s for a series of glycine site ligands with diverse chemical structures were also determined for the inhibition of [(3)H]-MDL105,519 binding to NR1-1a/NR2A receptors. L689,560 displayed similar binding characteristics to GV150,526A. It is suggested that glycine site antagonists may be divided into two classes based on their ability to distinguish between NR1 and NR1/NR2 receptors with respect to binding curve characteristics.

Animals↗
PubMed2000

Cyclooxygenase-1 is a marker for a subpopulation of putative nociceptive neurons in rat dorsal root ganglia.

Immunocytochemical and morphometric techniques were used to quantify the distribution of cyclooxygenase (cox)-containing neurons in rat L5 dorsal root ganglia (DRG). Cox-1 immunolabelling was almost exclusively restricted to small diameter DRG neurons (< 1000 microm2), and was extensively colocalized with calcitonin gene-related peptide (CGRP) and isolectin B4 (IB4). Cox-1 was present in 65% and 70% of CGRP- and IB4-labelled neurons, respectively. Cox-1 labelling was also found in neurons expressing the sensory neuron-specific (SNS) Na+ channel. Cox-2 labelling was absent in DRG from normal rats. In the Freund's adjuvant model of monoarthritis, the proportion of cox-1-positive DRG neurons was unchanged and no neurons were found to be labelled for cox-2. In primary tissue culture, cox-1 immunolabelling persisted in vitro for up to 9 days and was present in morphologically identical neurons. The selective expression of cox-1 in peripheral ganglia was confirmed by the small number of nodose ganglion neurons and superior cervical ganglion (SCG) neurons labelled for cox-1. These data suggest that cox-1 is a marker for a subpopulation of putative nociceptive neurons in vitro and in vivo, and suggests that the prostaglandins synthesized by these neurons may be important for nociceptor function. These data may have important implications for the mode and mechanism of action of non-steroidal anti-inflammatory drugs (NSAIDs).

Animals↗
PubMed1998

[3H]MDL 105,519 binds with equal high affinity to both assembled and unassembled NR1 subunits of the NMDA receptor.

[3H]MDL 105,519 (((E)-3-(2-phenyl-2-carboxyethenyl)-4,6-dichloro-1[3H]-indole-2-ca rboxylic acid) is a novel radioligand which binds with high affinity, Kd = 2.5 nM, to the glycine site of adult rodent forebrain, N-methyl-D-aspartate subtype of glutamate receptors. As with other glycine site antagonists, the major determinants for high-affinity binding of [3H]MDL 105,519 resides upon the NRI subunit, and not the NR2 subunits. [3H]MDL 105,519 binds with equal affinity, Kd = 3 nM, to both NR1-1a or NR1-4b splice variants, as well as the NRI-1a/NR2A receptor expressed in human embryonic kidney (HEK) 293 cells. One percent Triton X-100/1 M NaCl solubilises with a recovery of 15+/-3%, a mixed pool of assembled and unassembled forebrain NR1 subunit polypeptides. In this preparation, the recovery of [3H]MK801 ((+)-5-[3H]methyl-10,11-dihydrodibenzo[alpha,d]cyclohepten-5 ,10-imine binding activity (7+/-1%) reflects the amount of assembled NR1 subunits whereas [3H]MDL 105,519 binds quantitatively, with a recovery of 19+/-4% and Kd = 3 nM, to both assembled and unassembled NRI subunits. Therefore, [3H]MDL 105,519 should prove a useful ligand, in conjunction with immunopurification approaches, to address the question of NMDA receptor subunit stoichiometry.

Animals↗