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Biomedical subjects

M McCutcheon

Publications and source records attributed to M McCutcheon.

9 recordsLinked to original sources
PubMed1997

A sensitive ELISPOT assay to detect low-frequency human T lymphocytes.

We extended the sensitivity of the ELISPOT assay by including an antigen-driven proliferation step prior to a final restimulation with antigen and irradiated antigen presenting cells (APCs). This improved sensitivity made the modified ELISPOT assay better suited to the detection of rare or low frequency T lymphocytes than the standard ELISPOT assay or alternatives such as limiting dilution analysis or in situ hybridization. Use of ELISA-grade plastic or polyvinylidene difluoride (PVDF) plates for the detection of different cytokines improved the signal-to-noise ratio for counting cytokine spots, and use of video computer imaging software improved objective quantitation. Analysis of antigen-reactive peripheral blood mononuclear cells (PBMC) from multiple sclerosis (MS) patients using both the traditional and our modified ELISPOT assay demonstrate a > 10-fold increase in numbers of myelin basic protein (MBP)-responsive T cells detected (an average of less than 1 spot forming cell (SFC) per 2 x 10(5) PBMC with the standard assay compared to 19 SFC per 2 x 10(5) PBMC with the modified assay). In addition, the modified ELISPOT assay could be performed with frozen PBMC, which permitted greater flexibility in sample processing, multiple use of a single sample as an internal standard, and simultaneous analysis of samples collected at different time points. This modified ELISPOT assay has many applications, including analysis of cytokine profiles in rare T cell populations, identification of antigen-responsive individuals as PBMC donors for T lymphocyte cloning or for therapeutic intervention, and assessment of vaccine or therapeutic efficacy as a surrogate clinical marker.

Amino Acid Sequence↗
PubMed1995

Spontaneous swallowing rate and emotional state. Possible mechanism for stress-related gastrointestinal disorders.

Excessive spontaneous swallowing has been associated with a variety of common gastrointestinal symptoms including abdominal pain, heartburn, and bloating and may contribute to disorders such as hiatus hernia, duodenal ulcer, and irritable bowel syndrome. The present study investigated the hypothesis that changes in emotional state alter spontaneous swallowing rate. Subjects were 38 generally healthy undergraduates assigned to either a pleasant low arousal, neutral, or aversive high arousal condition. Each experimental session was divided into 30-min baseline and arousal manipulation periods. Spontaneous swallowing rate increased significantly with emotional arousal: for low, neutral, and high arousal groups, means were 7.9 +/- 1.9 (SE), 15.8 +/- 2.4, and 23.7 +/- 3.6 swallows/30 min, respectively. Other physiological and self-report measures, used to check the effectiveness of the arousal manipulation, varied appropriately with experimental procedures. These results indicate that changes in emotional state alter spontaneous swallowing rate in generally healthy individuals. Further research with patients is needed to establish whether stress-induced increases in swallowing rate produce or exacerbate clinically significant gastrointestinal symptomatology.

Adolescent↗
PubMed1995

Induction of tolerance in experimental autoimmune myasthenia gravis with solubilized MHC class II:acetylcholine receptor peptide complexes.

Stimulation of T lymphocytes through the T cell receptor in the absence of costimulatory signal(s) induces a state of unresponsiveness to subsequent antigen presentation. We have employed solubilized complexes consisting of rat class II MHC molecules containing an immunodominant peptide of the acetylcholine receptor (AChR alpha 100-116) to induce unresponsiveness in the autoreactive T lymphocytes mediating an animal model of myasthenia gravis. In vitro incubation of rat T cell lines specific for peptide AChR alpha 100-116 with solubilized complexes of MHC II and AChR alpha 100-116 (MHC II:AChR alpha 100-116) rendered the T cells unresponsive to subsequent stimulation by antigen presenting cells and the peptide. T cell lines with a broader specificity to the entire AChR protein pentamer had an 81% reduction in proliferation to AChR following a preincubation with solubilized MHC II:AChR alpha 100-116. Treatment with the solubilized MHC II:AChR alpha 100-116 induced phosphatidylinositol 4,5-bisphosphate hydrolysis, an early signalling event associated with binding to the TCR. Rats primed with AChR and injected intravenously with MHC II:AChR alpha 100-116 had reduced in vitro T cell proliferation to the AChR alpha 100-116 peptide and to whole AChR. Solubilized MHC II:AChR alpha 100-116 injected i.v. into rats exhibiting serological clinical symptoms of experimental autoimmune myasthenia gravis (EAMG) prevented death in 67% of the treated animals, compared to a 0-20% survival rate in all other control groups. These results demonstrate that solubilized MHC II complexed with an immunodominant autoantigenic peptide is tolerogenic and improves the survival rate of rats with EAMG, suggesting the basis for an antigen-specific therapy in autoimmune diseases such as MG.

Amino Acid Sequence↗
PubMed1990

The actions of cyclosporin A and FK506 suggest a novel step in the activation of T lymphocytes.

Cyclosporin A and FK506 are immunosuppressive compounds that have similar inhibitory effects on the expression of several lymphokines produced by T lymphocytes. Despite their similar effects the drugs bind to two different cytosolic protein, cyclophilin and FKBP respectively, which raises the possibility that they have different modes of action. Using constructs in which mRNA production controlled by a specific transcription factor could be readily measured we found that both cyclosporin A and FK506 completely inhibited transcription activated by NF-AT, NFIL2 A, NFIL2 B and partially inhibited transcription activated by NF kappa B. Cyclosporin A and FK506 inhibited only transcriptional activation that was dependent on Ca2+ mobilization. However, cyclosporin A and FK506 did not inhibit Ca2+ mobilization dependent expression of c-fos mRNA indicating that only a subset of signalling pathways regulated by Ca2+ is sensitive to these drugs. Furthermore, we did not observe any qualitative differences between the effect of cyclosporin A and FK506 on six different transcription factors which suggests that these drugs may interfere with the activity of a novel Ca2+ dependent step that regulates several transcription factors.

Anti-Bacterial Agents↗
PubMed1990

The development and functioning of the sense of shame.

An extensive literature on shame has not yet sufficiently addressed the nature and functioning of this affect from the psychoanalytic, developmental point of view. This paper tries to lay the ground for such a task.

Child↗
PubMed1989

Identification and characterization of a cell-surface molecule that is selectively induced on rat lymphokine-activated killer cells.

We have identified a 40- to 45-kDa cell-surface molecule designated gp42, that is expressed in high levels by rat lymphokine-activated killer (LAK) cells of NK cell origin. gp42 cannot be detected on the precursors of LAK cells and is not present on resting or activated T cells. Rather, expression of gp42 is selectively induced on NK cells by the high concentrations of rIL-2 that are required for the induction of LAK activity. Although the function of gp42 is not known, the selective nature of its expression suggests a role for this molecule in regulating responses that are unique to IL-2-activated NK cells.

Animals↗
PubMed1977

Differential analyses of EMG findings in motor neuron lesions.

The principle in electromyography that positive sharp waves (PSW) and fibrillation potentials (FP) are pathognomonic of lower motor neuron (LMN) pathology is challenged by recent reports that the same potentials are observed in upper motor neuron (UMN) lesions. We have also observed positive sharp waves and fibrillation potentials in patients with UMN lesions, without conditions that involve the LMN. This study was undertaken to ascertain if there are differences in the potentials between the LMN and UMN lesions. Twenty-five UMN and 25 LMN patients were electromyographed. Manual and computer analyses were used to compare parameters from positive sharp wave and fibrillation potentials. Our findings indicate that there are interlesion differences in the mean frequency of occurrence ratio of PSW to FP and in some of the durational wave parameters.

Adult↗