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Biomedical subjects

R M Stern

Publications and source records attributed to R M Stern.

At least 19 recordsLinked to original sources
PubMed1996

Cardiac spectral power reflects parasympathetic but not sympathetic nervous system activity in a clinical population.

The purpose of this short communication is to report our clinical findings regarding the use of the low frequency (LF, 0.02-0.15 Hz) and high frequency (HF, > 0.15 Hz) components of the spectral decomposition of heart-rate as indices of sympathetic (SNS) and parasympathetic nervous system (PNS) activity, respectively. Thirty-two females with histologically confirmed ovarian cancer, ranging in age from 46-72 years, participated in an autonomic assessment protocol consisting of a resting heart rate recording and several ANS function tests. The LF, HF and total power measures from the spectral decomposition were highly correlated with one another. In addition, the spectral components were most highly correlated with measures of PNS activity, i.e. standard deviation of heart rate at rest and the ratio of the six longest to the six shortest R-R intervals during deep breathing (E:I ratio). It is concluded, as other researchers have stated, that the use of the HF component of the HR spectrum as a measure of PNS activity is warranted, but caution must be used when interpreting the LF component.

Aged↗
PubMed1996

Effects of vection-induced motion sickness on gastric myoelectric activity and oral-cecal transit time.

The purpose of this study was to investigate the effects of vection-induced motion sickness on three cycle per minute gastric myoelectric activity and oral-cecal transit time. Forty-five subjects were exposed to a rotating optokinetic drum while electrogastrograms and subjective reports of symptoms were monitored. Prior to exposure, baseline breath hydrogen levels were established and subjects ingested vanilla pudding containing 10 g of lactulose. Breath hydrogen measurements were obtained before drum rotation and every 10 minutes after rotation, for 3 hr. Based on the severity of motion sickness symptoms reported, subjects were divided into two groups: a group susceptible to, and a group not susceptible to, vection-induced motion sickness. Averaged across subjects, the percentage of three cycle per minute activity decreased from baseline to rotation (3.6%) and from rotation to recovery (3.0%) [F(2/70)=2.43,P<0.1], with the susceptible group showing a greater overall decrease from baseline to recovery (8.9%), than the nonsusceptible group (4.2%) [F(1/35)=11.16,P<0.01]. The susceptible group had longer average oral-cecal transit times (144 min) than the nonsusceptible group (107 min) [t(36)=3.27,P<0.01]. Furthermore, symptom reports were positively correlated with oral-cecal transit times (r = 0.43, P < 0.05). In conclusion, vection-induced motion sickness is accompanied by decreased gastric three cycle per minute activity and prolonged oral-cecal transit times.

Adult↗
PubMed1996

Assessment of the multiple dimensions of nausea: the Nausea Profile (NP).

Nausea, unlike emesis, is a subjective experience that is difficult to describe to others, be they clinicians or researchers. Previous research has been limited to examining the frequency, severity, and duration of nausea. The goal of this study was to design a questionnaire that would allow for the evaluation of the characteristics of nausea across individuals and situations. This study consisted of 4 stages: descriptors were generated, categorized into 3 dimensions, and reevaluated to verify their reliability; in the final stage, the developed checklist was compared to a visual-analogue-scale (VAS) report of nausea in subjects exposed to a rotating optokinetic drum to stimulate nausea. The overall nausea checklist score and the VAS score were highly correlated (r = 0.71, p < 0.01). The development and use of the nausea checklist are discussed.

Adult↗
PubMed1996

Constricted expressiveness and psychophysiological reactivity in schizophrenia.

The present study investigated flat affect in schizophrenia within a multicomponent model of emotions in which affects were identified with the expression or display of feelings. Display, as well as other components of emotion, such as subjective experience and psychophysiological reactivity, were examined as 24 schizophrenic inpatients (12 with flat affect) and 12 depressed inpatients were guided through imagery of personal emotional experiences. It was hypothesized that display variables would show a relationship with flat affect, whereas physiological and subjective variables would not. Increased flatness of affect was associated with longer pauses and reduced dyadic interaction and less zygomatic (cheek) electromyogram activity. The flat affect patients unexpectedly showed more corrugator (brow) electromyogram activity compared with the depressed group, which perhaps reflects difficulty in self-expression. The flat affect group had faster heart rates at baseline. The groups did not, however, differ in self-report of the intensity of experienced emotion. These results support the view that flat affect patients show a reduction in emotional display, whereas other subsystems of emotion processing appear normally engaged.

Adult↗
PubMed1996

Functional disorders of the stomach.

Disorders of stomach function refer to neuromuscular abnormalities of gastric motility that involve the fundus, corpus, antrum, pylorus, and antroduodenal coordination. Symptoms related to disorders of stomach function are commonly meal-related; "dyspepsia" symptoms of epigastric fullness; or bloating, discomfort, and nausea in the postprandial period. Early satiety and prolonged stomach fullness are often present, and in severe cases the patient may vomit undigested food. Neuromuscular disorders of stomach function should not be considered until structural and metabolic diseases that may also cause these nonspecific symptoms are excluded. A thorough history, routine laboratory studies, ultrasound of the gallbladder and pancreas, and upper endoscopy will exclude the majority of diseases that may cause dyspepsia symptoms. Disorders of gastric neuromuscular function may be detected by solid-phase gastric emptying studies which detect gastroparesis and by electrogastrography which detects abnormalities of gastric myoelectrical activity termed gastric dysrhythmias. Invasive tests to determine abnormalities in gastric motility include intraluminal pressure and gastric tone/compliance recordings. Treatment approaches are limited at the present time and include dietary counseling and gastroprokinetic agents such as metoclopromide, cisapride, and erythromycin. Increased understanding of the pathophysiology of disorders of gastric neuromuscular function will lead to an improved and more rational armamentarium for the treatment of symptoms related to functional disorders of the stomach.

Diagnosis, Differential↗
PubMed1996

The effect of tilted stripes in an optokinetic drum on gastric myoelectric activity and subjective reports of motion sickness.

BACKGROUND: The effects of tilted and vertical optokinetic drum stripes on self-reports of motion sickness and electrogastrograms (EGG's) were measured to investigate possible differences in the effects of stripe orientation. The EGG is a non-invasive measure of gastric myoelectric activity. The normal frequency is 3 cpm, and dysrhythmic 4-9 cpm activity, gastric tachyarrhythmia, has been found to be associated with motion sickness symptoms, particularly nausea. It is theorized that these symptoms are related to a sensory mismatch between the visual and vestibular systems elicited by the drum's rotation. HYPOTHESIS: We hypothesized that tilted stripes would elicit more symptoms than vertical stripes due to an additional sensory mismatch between the visual and vestibular verticals. METHODS: We divided 45 subjects into 2 stripe orientation groups: Vertical, and Tilted 15 degrees in the direction of drum movement. After the subject sat inside the stationary drum for a 6-min baseline, the drum was rotated (10 rpm) for a maximum of 16 min, followed by a 6-min recovery period. Throughout the experiment we measured the subjects' EGG's and subjective symptoms of motion sickness (SSMS). RESULTS: During rotation and recovery, gastric tachyarrhythmic activity was higher for subjects in the Tilted condition; the difference between stripe conditions was significant during rotation (p < 0.05). There were, however, no differences between SSMS scores. CONCLUSIONS: Off-vertical stripes increase the dysrhythmic activity of the stomach that often precedes or accompanies nausea and other symptoms of motion sickness.

Adult↗
PubMed1995

P6 acupressure reduces symptoms of vection-induced motion sickness.

PURPOSE: The purpose of the study was to examine the effectiveness of P6 acupressure on nausea associated with visually-induced motion sickness. METHOD: There were 64 subjects randomly divided into 4 groups: P6 acupressure, dummy-point acupressure, sham P6 acupressure, and control. Each subject sat in an optokinetic drum for a 12-min baseline and 12-min drum rotation period. Subjects' electrogastrograms (EGG's) and subjective symptoms of motion sickness were obtained. RESULTS: The results indicated that the subjects in the P6 acupressure group reported significantly less nausea [F(3,60) = 8.16, p < 0.0001] during drum rotation period than those in the dummy-point acupressure, sham acupressure, and control groups. The scores for symptoms of motion sickness of the P6 acupressure group were significantly lower than those in the sham acupressure and control groups [F(3,60) = 3.49, p < 0.02]. Also, the subjects in the P6 acupressure group showed significantly less abnormal gastric myoelectric activity, tachyarrhythmia, than those in the sham acupressure and control groups [F(3,60) = 2.78, p < 0.04]. However, the subjects in the dummy-point acupressure group did not report significantly fewer symptoms and show less tachyarrhythmia than those in the sham acupressure and control groups. CONCLUSION: We conclude that P6 acupressure reduces the severity of symptoms of visually-induced motion sickness and gastric tachyarrhythmia.

Acupuncture Points↗
PubMed1995

Effects of dimenhydrinate on gastric tachyarrhythmia and symptoms of vection-induced motion sickness.

BACKGROUND: Previous research in our laboratory has shown that symptoms of motion sickness are accompanied by the loss of normal 3 cpm activity and the development of tachyarrhythmia in the electrogastrogram (EGG). HYPOTHESIS: We hypothesized that dimenhydrinate would prevent the development of gastric tachyarrhythmia and reduce symptoms of motion sickness. METHODS: Twenty health volunteers were tested in a counter-balanced, within-subject, double-blind design. Subjects were exposed to a rotating optokinetic drum to induce vection after receiving either dimenhydrinate (100 mg) or a placebo on two separate occasions. EGG's were recorded immediately before ingestion of capsules, 1 h after ingestion, and during rotation. Motion sickness symptom reports (SSMS) were obtained prior to and during rotation. RESULTS: The average SSMS score was 5.9 points higher after placebo administration than after dimenhydrinate administration (t[19] = 4.87, P < 0.001). Significantly more subjects requested early termination of the rotating drum due to severe symptoms after placebo administration than after dimenhydrinate administration (McNemar's chi 2[1] = 6.00, p < 0.05). Drowsiness reports were significantly higher after dimenhydrinate administration than after placebo administration (t[19] = 2.65, p < 0.05). Analysis of EGG's showed a significant decrease in normal 3 cpm and tachyarrhythmic activity after dimenhydrinate, but no change after placebo (SR[19] = 53, p < 0.02 and SR[19] = 68, p < 0.01 respectively). During drum rotation gastric tachyarrhythmias increased significantly in the placebo condition (SR[18] = -0.61.5, p < 0.01), but not in the dimenhydrinate condition. EGG's were not significantly different between conditions. CONCLUSIONS: We conclude that dimenhydrinate reduced motion sickness symptoms at least in part by depressing central nervous system activity and possibly by suppressing abnormal gastric myoelectric activity.

Adolescent↗
PubMed1994

Effects of phenytoin on vection-induced motion sickness and gastric myoelectric activity.

The purpose of this study was to test the prophylactic effects of a single low dose of phenytoin on motion sickness. In this double-blind study, fasted male subjects who were susceptible to motion sickness were given either a 200-mg tablet of phenytoin (N = 19) or a placebo (N = 16). Electrogastrograms (EGG's) were recorded predrug, postdrug (4 h after ingestion of drug), before drum rotation, and during drum rotation. During testing, subjects were exposed to an optokinetic drum which was stationary for 8 min and which then rotated at 10 rpm for 16 min. The results showed that the phenytoin subjects had a lower mean subjective symptom score than the placebo group (5.8 vs. 7.1), but the difference was not significant. However, 6 of 16 placebo subjects requested early termination of drum rotation due to symptom severity, whereas only 2 of 19 phenytoin subjects terminated testing prematurely (X2 = 3.89, p < 0.05). The phenytoin group showed no increase in gastric tachyarrhythmia, the pattern of gastric myoelectric activity that usually accompanies nausea, during drum rotation, whereas tachyarrhythmia doubled for the placebo group. In conclusion, we have demonstrated that a single low dose of phenytoin prevents the development of gastric tachyarrhythmia and decreases the intensity of motion sickness symptoms.

Adult↗
PubMed1993

Hypothalamic and gastric myoelectrical responses during vection-induced nausea in healthy Chinese subjects.

The physiology of nausea, a uniquely human symptom, is poorly understood. The purpose of this study was to measure the temporal sequences of neurohormonal responses and gastric myoelectrical activity in healthy subjects during the rotation of an optokinetic drum that produced nausea and other symptoms of motion sickness. Plasma catecholamines, vasopressin, and cortisol were measured at baseline, during minutes 1-5, 6-10, and 11-15 of drum rotation, and after rotation stopped. Electrogastrograms were recorded throughout the study. Twelve subjects (80%) developed nausea and 4-9 cycles/min of gastric tachyarrhythmias; three subjects had no nausea and no gastric dysrhythmias. Tachyarrhythmias began 3.4 +/- 0.8 min after the onset of drum rotation, and nausea was reported, on average, 3 min later. During minutes 6-10 of drum rotation, vasopressin levels significantly increased in the subjects with nausea compared with subjects without nausea (P < 0.04). In the subjects with nausea, epinephrine and vasopressin increased significantly (P < 0.05) compared with baseline during minutes 6-10 and 11-15 of drum rotation. As nausea resolved during recovery, vasopressin decreased by 74%, whereas epinephrine increased 13%. We conclude that 1) in nauseated subjects, endogenous vasopressinergic and sympathetic circuits are activated before hypothalamic-pituitary-adrenal pathways, 2) plasma vasopressin levels correlate most closely with the temporal onset and resolution of nausea, and 3) peripheral gastric dysrhythmias may have a role in activating central vasopressinergic neurons.

Adult↗
PubMed1993

Chinese hyper-susceptibility to vection-induced motion sickness.

Little is known about the factors that control individual differences in susceptible to motion sickness. A serendipitous observation in our laboratory that most Chinese subjects become motion sick prompted this study. We used a rotating optokinetic drum to provoke motion sickness and compared gastric responses and symptom reports of Chinese, European-American, and African-American subjects. There was no difference in the responses of European-American and African-American subjects; however, Chinese subjects showed significantly greater disturbances in gastric activity and reported significantly more severe symptoms. We suggest that this hyper-susceptibility presents a natural model for the study of physiological mechanisms of nausea and other symptoms of motion sickness.

Adult↗
PubMed1993

Effects of scopolamine on autonomic profiles underlying motion sickness susceptibility.

The purpose of this study was to examine the effects of scopolamine on the physiological patterns occurring prior to and during motion sickness stimulation. In addition, the use of physiological profiles in the prediction of motion sickness was evaluated. Sixty subjects ingested either 0.6 mg scopolamine, 2.5 mg methscopolamine, or a placebo. Heart rate (HR), respiratory sinus arrhythmia (an index of vagal tone), and electrogastrograms were measured prior to and during the exposure to a rotating optokinetic drum. Compared to the other groups, the scopolamine group reported fewer motion sickness symptoms, and displayed lower HR, higher vagal tone, enhanced normal gastric myoelectric activity, and depressed gastric dysrhythmias before and during motion sickness induction. Distinct physiological profiles prior to drum rotation could reliably differentiate individuals who would develop gastric discomfort from those who would not. Symptom-free subjects were characterized by high levels of vagal tone and low HR across conditions, and by maintaining normal (3 cpm) electrogastrographic activity during drum rotation. It was concluded that scopolamine offered motion sickness protection by initiating a pattern of increased vagal tone and gastric myoelectric stability.

Adult↗
PubMed1992

Electrical acustimulation relieves vection-induced motion sickness.

The aim of this study was to examine the effects of electrical acustimulation on gastric myoelectric activity and severity of symptoms of motion sickness. In experiment 1, 16 Chinese subjects received electrical acustimulation in one of two sessions. In experiment 2, 45 white and black American subjects were randomly divided into three groups: acustimulation, sham acustimulation, and control. Each subject sat in an optokinetic drum for 15 minutes baseline and 15 minutes of drum rotation. Subjects' electrogastrograms and subjective symptoms of motion sickness were obtained. In experiment 1, the mean symptom score and tachyarrhythmia during acustimulation sessions were significantly lower than during no-acustimulation sessions. In experiment 2, the mean symptom score of the acustimulation group was significantly lower than that of the sham-stimulation group and the control group; tachyarrhythmia in the acustimulation group was significantly less than that of the control group but not the sham-stimulation group. In conclusion, electrical acustimulation reduces the severity of symptoms of motion sickness and appears to decrease gastric tachyarrhythmia.

Adult↗
PubMed1992

Effects of eating on vection-induced motion sickness, cardiac vagal tone, and gastric myoelectric activity.

This study investigated the effect of food ingestion on motion sickness severity and its physiological mechanisms. Forty-six fasted subjects were assigned either to a meal group or to a no-meal group. Electrogastrographic (EGG) indices (normal 3 cpm activity and abnormal 4-9 cpm tachyarrhythmia) and respiratory sinus arrhythmia (RSA) were measured before and after a meal and during a subsequent exposure to a rotating drum in which illusory self-motion was induced. The results indicated that food intake enhanced cardiac parasympathetic tone (RSA) and increased gastric 3 cpm activity. Postprandial effects on motion sickness severity remain equivocal due to group differences in RSA baseline levels. During drum rotation, dysrhythmic activity of the stomach (tachyarrhythmia) and vagal withdrawal were observed. Furthermore, high levels of vagal tone prior to drum rotation predicted a low incidence of motion sickness symptoms, and were associated positively with gastric 3 cpm activity and negatively with tachyarrhythmia. These data suggest that enhanced levels of parasympathetic activity can alleviate motion sickness symptoms by suppressing, in part, its dysrhythmic gastric underpinnings.

Adult↗
PubMed1991

Lateralization of rectangularly modulated noise: explanations for counterintuitive reversals.

A number of years ago Hafter and Shelton [J. Acoust. Soc. Am. Suppl. 1 68, S16 (1980), Hafter and Shelton, J. Acoust. Soc. Am. 90, 1901-1907 (1991)] demonstrated that diotic bandpass noise that is multiplied by a dichotic pair of periodic rectangular gating functions could be strongly perceived toward the ear receiving the signal with the gating function that is lagging in time. These results were surprising because sounds presented with interaural time delays (ITDs) are normally perceived toward the ear receiving the signal that is leading in time. In order to better understand these counterintuitive phenomena an analytical expression for the cross-correlation function of these gated-noise stimuli is derived, and it is shown that many of the general properties of the data can be accounted for by considering only the properties of this function. The lateralization of the gated-noise stimuli is compared to predictions of three types of models of binaural signal processing: models based on the cross-correlation function of the entire signal, models based on the interaural group delay or phase delay at low frequencies, and the position-variable model, which is based on the response of the peripheral auditory system to the stimuli. It is shown that the observed lateralization results, including the unexpected reversals and various frequency effects, can be explained without further assumption by an extended implementation of the position-variable model [Stern and Colburn, J. Acoust. Soc. Am. 64, 127-140 (1978)]. The cross-correlation functions of the original stimuli can also be related to the lateralization data, but in a much less natural fashion. It is argued that models based on the interaural group delay of the original stimuli will not describe the observed results, although low-frequency phase delay is qualitatively consistent with the observed lateralization phenomena.

Attention↗
PubMed1991

Assessing environmental carcinogens: review of an approach adopted by the expert groups of the World Health Organization Regional Office for Europe.

The World Health Organization Regional Office for Europe has adopted the viewpoint that it is necessary to attempt to evaluate potential human carcinogens in such a way so that the risk they present can be compared and used in general consideration of protecting the public from toxic substances found in various environments. In order to demonstrate this process, the evaluations for a number of criteria air pollutants as presented in the volume Air Quality Guidelines for Europe are summarized and reviewed. The basic method used is that involving the estimation of risk based on lifetime exposures to airborne carcinogens by a linear extrapolation from known data using no threshold, with the carcinogenic potency expressed as the incremental unit risk estimate. This unit risk is defined as the average expected for a hypothetical population exposed for a lifetime to a concentration of one microgram per cubic meter of the agent in the air they breathe. The advantages and disadvantages of the method are reviewed, and background information for actual environmental conditions and risks leading up to the consensus guidelines adopted are presented for those 17 of the initial 28 criteria air pollutants treated which have IARC classifications of carcinogenicity.

Air Pollutants↗
PubMed1991

Effects of pre-exposures to a rotating optokinetic drum on adaptation to motion sickness.

The purpose of this study was to investigate the effects of two different pre-exposure procedures on adaptation to motion sickness in a rotating circular vection drum. The 45 subjects were randomly divided into three groups. The control group only had a standard 16-min exposure to the drum rotating at 60 degrees/s with no pre-exposure. The incremental exposure group had two separated 4-min pre-exposure periods at 15 degrees/s and 30 degrees/s in the rotating drum immediately prior to the standard 16-min exposure period in the drum rotating at 60 degrees/s. The abrupt-exposure group had the same pre-exposure procedure except the pre-exposure drum rotation speed was 60 degrees/s and was followed by the same standard exposure periods. Subjective motion sickness reports and a measure of gastric myoelectric activity (electrogastrogram, EGG) were obtained during the standard 16-min drum rotation period in all three groups. The results showed that subjects in the incremental exposure group reported significantly fewer motion sickness symptoms during the standard 16-min rotation period than did the subjects in the abrupt exposure group and the control group. Subjects in the incremental exposure group also had less tachyarrhythmia, abnormal gastric myoelectric activity associated with nausea, during the 16-min rotation period than did the subjects in the control and abrupt exposure group. Incremental exposure to motion stimuli may be a useful method for training resistance to visually-induced motion sickness.

Adaptation, Physiological↗