Biomedical subjects

J R Stowell

Publications and source records attributed to J R Stowell.

3 recordsLinked to original sources

PubMed2001

Perceived stress and cellular immunity: when coping counts.

This cross-sectional study investigated whether active and avoidance coping methods were differentially related to immune function depending on stress level. Perceived stress and coping method were assessed in 173 healthy older adults and related to the number and percentage of CD3+, CD4+, and CD8+ T lymphocytes as well as the proliferative response of peripheral blood leukocytes to phytohemagluttinin (PHA) and concanavalin A (Con A). Both active and avoidance coping significantly interacted with perceived stress on proliferative responses to both mitogens. Higher levels of active coping were significantly related to a more vigorous proliferative response to PHA and Con A, particularly at high stress levels. At low stress levels, active coping was not significantly related to proliferative responses, whereas avoidance coping was significantly associated with a greater proliferative response to Con A. These results suggest that the relationships between certain coping methods and immune function depend on perceived stress level.

Adaptation, Psychological↗

PubMed2000

Attenuation of the bidirectional effects of chlordiazepoxide and FG 7142 on conditioned response suppression and associated cardiovascular reactivity by loss of cortical cholinergic inputs.

RATIONALE: Basal forebrain cortical cholinergic projections have been hypothesized to mediate the enhanced cardiovascular defensive response initiated by the putative anxiogenic benzodiazepine receptor (BZR) partial inverse agonist FG 7142 (FG). The present study was designed to test the broader hypothesis that the integrity of this cholinergic projection is required for the mediation of the bidirectional modulatory effects of BZR agonists and inverse agonists on anxiety and associated cardiovascular reactivity. OBJECTIVES: The interactions between the effects of 192 IgG-saporin-induced lesions of basal forebrain corticopetal cholinergic neurons and of the BZR agonist chlordiazepoxide (CDP) and FG on the performance of rats tested in a conditioned suppression paradigm and on associated cardiovascular reactivity were assessed. METHODS: Lesioned and control animals were equipped with a telemetric device to record heart rate, trained in an operant lever task, and then tested for suppression of responding during presentation of a conditioned stimulus (CS) and a general contextual cue that was previously associated with shock. FG, CDP (8 mg/kg) and vehicle were administered IP in separate extinction sessions. RESULTS: In control animals, operant responding was suppressed during presentation of the CS and contextual cue. Administration of FG enhanced this suppression, while CDP attenuated it. Lesions attenuated overall response suppression as well as the modulatory effects of BZR ligands on responding during presentation of the contextual stimulus. Likewise, lesions attenuated the cardioacceleratory response to the contextual stimulus and the ability of the BZR ligands to modulate this response. CONCLUSIONS: The behavioral and autonomic responses to anxiety-related stimuli, as well as the modulatory effects of BZR ligands, are mediated in part via cortical cholinergic inputs.

Animals↗

PubMed1998

ECG artifacts and heart period variability: don't miss a beat!

The impact of artifacts on estimates of heart period variability were evaluated by modeling the effects of missed R-waves and spurious R-wave detections in actual and simulated heart period series. Results revealed that even a single artifact, occurring within a 128-s interbeat interval series, can impart substantial spurious variance into all commonly analyzed frequency bands, including that associated with respiratory sinus arrhythmia. In fact, the spurious variance introduced by a single artifact may be greater than that associated with true basal heart period variability and can far exceed typical effect sizes in psychophysiological studies. The effects of artifacts are not related to a specific analytical method and are apparent in both frequency and time domain analyses. Results emphasize the importance of artifact detection and resolution for studies of heart period variability.

Computer Simulation↗