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Biomedical subjects

K L Koch

Publications and source records attributed to K L Koch.

At least 19 recordsLinked to original sources
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↗
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

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↗
PubMed1991

Motion sickness severity and physiological correlates during repeated exposures to a rotating optokinetic drum.

Fifty-two subjects were exposed to a rotating optokinetic drum. Ten of these subjects who became motion sick during the first session completed two additional sessions. Subjects' symptoms of motion sickness, perception of self-motion, electrogastrograms (EGGs), heart rate, mean successive differences of R-R intervals (RRI), and skin conductance were recorded for each session. The results from the first session indicated that the development of motion sickness was accompanied by increased EGG 4-9 cpm activity (gastric tachyarrhythmia), decreased mean successive differences of RRI, increased skin conductance levels, and increased self-motion perception. The results from the subjects who had three repeated sessions showed that 4-9 cpm EGG activity, skin conductance levels, perception of self-motion, and symptoms of motion sickness all increased significantly during the drum rotation period of the first session, but increased significantly less during the following sessions. Mean successive differences of RRI decreased significantly during the drum rotation period for the first session, but decreased significantly less during the following sessions. In conclusion, we have demonstrated that the development of motion sickness is accompanied by an increase in gastric tachyarrhythmia, and an increase in sympathetic activity and a decrease in parasympathetic activity, and that adaptation to motion sickness is accompanied by the recovery of autonomic nervous system balance.

Adaptation, Physiological↗
PubMed1990

Gastric dysrhythmias and nausea of pregnancy.

Gastric dysrhythmias have been recorded from patients with a variety of nausea syndromes. The aim of this study was to measure gastric myoelectric activity in women with and without nausea during the first trimester of pregnancy. In 32 pregnant women gastric myoeletric activity was recorded for 30-45 min with cutaneous electrodes that yielded electrogastrograms (EGGs). Frequencies of the EGG waves were analyzed visually and by computer. Subjects rated their nausea at the time of EGG recording on a visual analog scale with 0 representing no nausea and 300 mm severe nausea. Gastric dysrhythmias were found in 26 pregnant subject: Seventeen had tachygastrias (EGG frequencies of 4-9 cpm), five had 1- to 2-cpm EGG waves, and four had flat-line patterns Mean nausea scores of the subjects with tachygastrias, 1- to 2-cpm, and flat-line patterns were 64.8 +/- 13, 93.4 +/- 23, and 77.2 +/- 36, respectively. Six pregnant subjects had normal 3-cpm EGG patterns, and their nausea scores averaged 2.8 +/- 1.1 (P less than 0.05 compared with nausea scores in subjects with tachygastrias, 1- to 2-cpm, and flat-line rhythms). Six subjects with gastric dysrhythmias during pregnancy were restudied after delivery; each of these subjects had normal 3-cpm EGG patterns and none had nausea. Thus, gastric dysrhythmias are objective pathophysiologic events associated with symptoms of nausea reported during the first trimester of pregnancy.

Adult↗
PubMed1990

Ischemic gastroparesis: resolution after revascularization.

Patients with chronic nausea and vomiting frequently present challenging diagnostic and therapeutic problems. In such patients, gastroparesis of unknown cause, or "idiopathic" gastroparesis, may be the only objective finding. Two middle-aged women with nausea, vomiting, and weight loss of 10 and 26 kg over 6 and 18 months, respectively, were evaluated. Routine laboratory and barium study results were normal. Solid-phase gastric emptying studies showed severe gastroparesis in both patients. Upper endoscopies excluded gastric outlet obstruction. Gastric dysrhythmias (4-cpm and 1-cpm patterns) were recorded using cutaneous electrodes. An abdominal bruit was ascultated in one patient. Abdominal arteriograms in both patients showed total occlusion of all three major mesenteric vessels with collaterals supplied via hemorrhoidal arteries. Bypass grafting procedures of the celiac and superior mesenteric arteries in one patient and of the celiac artery in the other patient were performed. Six months after mesenteric artery revascularization, upper gastrointestinal symptoms had resolved and original weights were regained. Furthermore, normal 3-cpm gastric myoelectrical activity and normal gastric emptying of solids were restored in both patients. In these patients, chronic mesenteric ischemia resulted in a novel and reversible cause of gastroparesis, gastric dysrhythmias, and accompanying symptoms.

Blood Vessel Prosthesis↗
PubMed1990

Neuroendocrine and gastric myoelectrical responses to illusory self-motion in humans.

We compared gastric myoelectrical activity and endogenous neuroendocrine responses in subjects with and without motion sickness elicited by illusory self-motion or vection. Rotating a drum with black and white vertical stripes around seated stationary subjects (n = 22) produced vection. Gastric myoelectrical activity was recorded with cutaneous electrodes. Thirteen subjects developed gastric dysrhythmias [4- to 9-cycles/min (cpm) signals] and motion sickness during vection, whereas nine subjects maintained normal 3-cpm gastric rhythms and remained symptom free. Base-line plasma cortisol and beta-endorphin levels were significantly greater (P less than 0.01) in the subjects who would develop gastric dysrhythmias and nausea compared with the subjects who would not develop motion sickness. Norepinephrine levels increased in the nauseated group immediately after vection ceased (354.6 +/- 41.1 pg/ml) compared with the symptom-free subjects (223.1 +/- 22.8 pg/ml, P less than 0.05). Epinephrine increased significantly (P less than 0.05) after vection only in the nauseated subjects, whereas dopamine levels were not altered by vection in either group. We conclude that 1) anticipatory increases in plasma cortisol and beta-endorphin occurred in subjects who would develop nausea and gastric tachyarrhythmias during vection; 2) endogenous epinephrine and norepinephrine were increased in subjects who had vection-induced nausea and gastric dysrhythmias; and 3) vection stimulates brain-gut interactions, resulting in gastric tachyarrhythmias and complex neuroendocrine responses in subjects with motion sickness.

Adult↗
PubMed1990

Vasopressin and oxytocin responses to illusory self-motion and nausea in man.

Vasopressin and oxytocin are nonapeptides secreted from the neurohypophysis; increases in vasopressin are associated with nausea and vomiting in some, but not all, species. Our aim was to determine whether plasma vasopressin and oxytocin levels were altered in healthy volunteers who did or did not develop nausea during vection, an optokinetic stimulus which produces the illusion of self-motion. Vection was produced by rotating a drum with an inner surface of black and white vertical stripes around the seated stationary subject. Gastric myoelectrical activity was recorded continuously throughout the experiment with electrodes positioned on the abdominal surface. Plasma samples were obtained before vection and after drum rotation stopped when nausea and tachygastria were present. Vasopressin and oxytocin were extracted from plasma and quantified by RIA. During vection six subjects reported nausea and developed gastric dysrhythmias; six other subjects had no nausea and remained in normal 3-cpm myoelectrical rhythms. Vasopressin and oxytocin values before vection were similar in each group of subjects. One minute after vection stopped, plasma vasopressin levels were significantly greater (P less than 0.05) in subjects experiencing nausea and tachygastrias (35.4 +/- 26.7 pmol/L) than in those without symptoms (2.7 +/- 0.47 pmol/L). Oxytocin levels were unchanged by either vection or nausea. It is concluded that 1) vasopressin, not oxytocin, neurons in the magnocellular-neurohypophyseal system are activated during vection-induced nausea and gastric dysrhythmias; and 2) illusory self-motion may be used safely to study the neuroendocrine responses to brain-gut interactions and nausea in man.

Adult↗
PubMed1990

Afferent loop obstruction presenting as acute pancreatitis and pseudocyst: case reports and review of the literature.

Afferent loop obstruction after gastrectomy and Billroth II reconstruction is an uncommon problem. Complete acute obstruction requires emergent laparotomy. However, chronic obstruction may begin insidiously and its symptoms may reflect other gastrointestinal diseases. Two patients are described who developed acute abdominal pain, marked hyperamylasemia, and palpable abdominal masses 5 and 15 years after Billroth II gastrectomy. The masses were initially interpreted as pancreatic pseudocysts. Both patients were found to have chronically obstructed afferent limbs, and in one the obstruction was associated with hundreds of stasis stones within the afferent limb. Surgical decompression was accomplished in each patient. Patients who have undergone Billroth II reconstruction have signs, symptoms, and laboratory findings consistent with acute pancreatitis. A history of previous gastrectomy, recurrent or severe abdominal pain, hyperamylasemia with characteristic tomography, and endoscopic findings will establish the diagnosis and necessitate surgical evaluation and intervention.

Acute Disease↗
PubMed1990

The effects of fixation and restricted visual field on vection-induced motion sickness.

Approximately 60% of healthy human subjects experience motion sickness when exposed to a rotating optokinetic drum. The purpose of the present study was to determine the effects of certain visual factors on susceptibility to motion sickness. Vection data (illusory self-motion), horizontal eye movement recordings, subjective motion sickness report, and a measure of gastric myoelectric activity (electrogastrogram, EGG) were obtained from 45 subjects, who were randomly divided into the following three groups: a control group that observed the entire visual field with no fixation, a group that fixated on a central target, and a third group that had a visual field restricted to 15 degrees. The experimental session was divided into the following three 12-min periods: baseline, drum rotation, and recovery. The results showed that fixation greatly reduced nystagmus and slightly reduced vection. The restricted visual field slightly reduced nystagmus and greatly reduced vection. Both of these manipulations significantly reduced symptoms of motion sickness and tachyarrhythmia, the abnormal gastric myoelectric activity that usually accompanies nausea.

Electromyography↗