Biomedical subjects
Robert M Stern
Publications and source records attributed to Robert M Stern.
Relationship between temporal changes in cardiac parasympathetic activity and motion sickness severity.
Chemotherapy-induced nausea has been associated with a time-related decrease in cardiac parasympathetic activity. We tested the hypothesis that a time-related decrease in cardiac parasympathetic activity would also be associated with nausea and other motion sickness symptoms during illusory self-motion (vection). Fifty-nine participants (aged 18-34 years: 25 male) were exposed to a rotating optokinetic drum to induce vection. Symptoms of motion sickness and an estimate of cardiac parasympathetic activity (respiratory sinus arrhythmia; RSA) were obtained at baseline and throughout a drum-rotation period. As expected, motion sickness symptoms increased and RSA decreased over time during drum rotation. Moreover, greater decreases in RSA over time correlated with greater motion sickness severity. These results suggest that a time-related decrease in cardiac parasympathetic activity may be an important correlate of nausea and motion sickness across different evocative contexts.
Reduction in serum cortisol after platinum based chemotherapy for cancer: a role for the HPA axis in treatment-related nausea?
Many adverse effects commonly associated with chemotherapy, such as nausea, vomiting, and fatigue, are also characteristic of adrenal insufficiency. It is conceivable that chemotherapy drugs may directly or indirectly impact the activity of the hypothalamic-pituitary-adrenal axis. We examined this conjecture by characterizing temporal changes in blood cortisol concentrations in women with ovarian carcinoma given chemotherapy. Twenty-three chemotherapy-naïve women with histologically confirmed ovarian cancer underwent serial blood sampling for determination of cortisol levels prior to and every hour for 6 hr following two chemotherapy treatments with cisplatin or carboplatin. Samples were also taken for 4 hr on a comparison day when all study procedures were performed except chemotherapy administration. A significant reduction in serum cortisol was found immediately following infusion of either cisplatin or carboplatin. No progressive reduction in cortisol was found over the two treatment cycles. Because the reduction in cortisol was seen only in the presence of the cytotoxic drug, it is likely that the effect of the drug is "direct" and does not involve overt psychological or circadian mechanisms. The possible role of this reduction in cortisol is discussed in relation to induction of chemotherapy-induced nausea and vomiting.
Changes in gastric myoelectric activity during space flight.
The purpose of the present study was to examine postprandial myoelectric activity of the stomach and gastric activity associated with space motion sickness using electrogastrography. Three crewmembers participated in this investigation. Preflight, subjects exhibited normal postprandial responses to the ingestion of a meal. Inflight, crewmembers exhibited an abnormal decrease in the power of the normal gastric slow wave after eating on flight day 1, but had a normal postprandial response by flight day 3. Prior to and during episodes of nausea and vomiting, the electrical activity of the stomach became dysrhythmic with 60-80% of the spectral power in the bradygastric and tachygastric frequency ranges. These findings indicate that gastric motility may be decreased during the first few days of space flight. In addition, changes in the frequency of the gastric slow wave associated with space motion sickness symptoms are consistent with those reported for laboratory-induced motion sickness.
Spatial task performance, sex differences, and motion sickness susceptibility.
There are substantial individual differences in susceptibility to motion sickness, yet little is known about what mediates these differences. Spatial ability and sex have been suggested as possible factors in this relationship. 89 participants (57 women) were administered a Motion Sickness Questionnaire that assesses motion sickness susceptibility, a Water-level Task that gauges sensitivity to gravitational upright, and a Mental Rotation Task that tests an individual's awareness of how objects typically move in space. Significant sex differences were observed in performance of both the Water-level Task (p<.01), and the Mental Rotation Task (p<.005), with women performing less accurately than men. Women also had significantly higher scores on the Motion Sickness Questionnaire (p<.005). Among men, but not women, significant negative relationships were observed between Water-level Task performance and Motion Sickness Questionnaire score (p<.001) and between Mental Rotation Task performance and Motion Sickness Questionnaire score (p<.005). In conclusion, women performed significantly more poorly than men did on the spatial ability tasks and reported significantly more bouts of motion sickness. In addition, men showed a significant negative relationship between spatial ability and motion sickness susceptibility.