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Biomedical subjects

P G Kaufmann

Publications and source records attributed to P G Kaufmann.

At least 19 recordsLinked to original sources
PubMed2001

Sex differences in chest pain in patients with documented coronary artery disease and exercise-induced ischemia: Results from the PIMI study.

BACKGROUND: Sex differences in the pathophysiologic course of coronary artery disease (CAD) are widely recognized, yet accurate diagnosis of coronary artery disease in women remains challenging. METHODS: To determine sex differences in the clinical manifestation of CAD, we studied chest pain reported during daily activities, exercise, and mental stress in 170 men and 26 women. All patients had documented CAD (>50% narrowing in at least 1 major coronary artery or prior myocardial infarction) and all had 1-mm ST-segment depression on treadmill exercise. We collected psychologic test results, serum samples (potassium, epinephrine, norepinephrine, cortisol, b-endorphin, and glucose), and cardiac function, sensory threshold, and autonomic function data at specified times before, during, or after exercise and mental stress tests to assess measures of depression, anxiety, and neurohormonal and thermal pain perception. RESULTS: Women reported chest pain more often than men during daily activities (P =.04) and during laboratory mental stressors (P =.01) but not during exercise. Men had lower scores than women on measures of depression, trait anxiety, harm avoidance, and reward dependence (P <.05 for all). Women had significantly lower plasma b-endorphin levels at rest (4.2 +/- 3.9 vs 5.0 +/- 2.5 pmol/L for men, P =.005) and at maximal mental stress (6.4 +/- 5.1 vs 7.4 +/- 3.5 pmol/L for men, P <.01). A higher proportion of women than men had marked pain sensitivity to graded heat stimuli applied to skin (hot pain threshold <41 degrees C, 33% vs 10%, P =.001). CONCLUSIONS: Our results reflect sex differences in the affective and discriminative aspects of pain perception and may help explain sex-related differences in clinical presentations.

Activities of Daily Living↗
PubMed2000

Stress management intervention for primary prevention of hypertension: detailed results from Phase I of Trials of Hypertension Prevention (TOHP-I).

PURPOSE: Stress Management Intervention (SMI) was one of seven nonpharmacologic approaches evaluated in Phase I Trials of Hypertension Prevention (TOHP-I) for efficacy in lowering diastolic blood pressure (BP) in healthy men and women aged 30 to 54 years with diastolic BP 80-89 mm Hg. METHODS: A total of 242 and 320 participants were randomized to SMI or an "assessment only" SMI Control, respectively, at four clinical centers. The SMI consisted of 37 contact hours in 21 group and two individual meetings over 18 months and included: training in four relaxation methods, techniques to reduce stress reactions, cognitive approaches, communication skills, time management, and anger management within a general problem-solving format. Standardized protocols detailed methods and timing for collecting BP, psychosocial measures, and urinary samples from both SMI and SMI Control participants. RESULTS: In intention-to-treat analyses, although significant baseline to termination BP reductions were observed in both groups, net differences between the SMI and SMI Control groups' BP changes (mean (95% CI)) were not significant: -0.82 (-1.86, 0.22) for diastolic BP, and -0.47 (-1.96, 1.01) for systolic BP. Extensive adherence sub-group analyses found one effect: a significant 1.36 mm Hg (p = 0.01) reduction in diastolic BP relative to SMI Controls at the end of the trial for SMI participants who completed 61% or more of intervention sessions. CONCLUSIONS: While the TOHP-I SMI was acceptable to participants as evident from high levels of session completion, the absence of demonstrated BP lowering efficacy in intention-to-treat analyses suggests that the TOHP-I SMI is an unlikely candidate for primary prevention of hypertension in a general population sample similar to study participants. The isolated finding of significant diastolic BP lowering in SMI participants with higher adherence provides very weak evidence of SMI BP lowering efficacy and may be a chance finding. Whether similar or other stress management interventions can produce significant BP lowering in populations selected for higher levels of BP, stress, or intervention adherence remains to be demonstrated.

Adult↗
PubMed1999

Relationship among mental stress-induced ischemia and ischemia during daily life and during exercise: the Psychophysiologic Investigations of Myocardial Ischemia (PIMI) study.

OBJECTIVES: The purposes of this database study were to determine: 1) the relationship between mental stress-induced ischemia and ischemia during daily life and during exercise; 2) whether patients who exhibited daily life ischemia experienced greater hemodynamic and catecholamine responses to mental or physical stress than patients who did not exhibit daily life ischemia, and 3) whether patients who experienced daily life ischemia could be identified on the basis of laboratory-induced ischemia using mental or exercise stress testing. BACKGROUND: The relationships between mental stress-induced ischemia in the laboratory and ischemia during daily life and during exercise are unclear. METHODS: One hundred ninety-six stable patients with documented coronary disease and a positive exercise test underwent mental stress testing and bicycle exercise testing. Radionuclide ventriculography and electrocardiographic (ECG) monitoring were performed during the mental stress and bicycle tests. Patients underwent 48 h of ambulatory ECG monitoring. Hemodynamic and catecholamine responses were obtained during mental stress and bicycle tests. RESULTS: Ischemia (reversible left ventricular dysfunction or ST segment depression > or = 1 mm) developed in 106 of 183 patients (58%) during the mental stress test. There were no significant differences in clinical characteristics of patients with, compared with those without, mental stress-induced ischemia. Patients with mental stress ischemia more often had daily life ischemia than patients without mental stress ischemia, but their exercise tests were similar. Patients with daily life ischemia had higher ejection fraction and cardiac output, and lower systemic vascular resistance during mental stress than patients without daily life ischemia. Blood pressure and catecholamine levels at rest and during the mental stress tests were not different in patients with, compared with those without, daily life ischemia. Patients with daily life ischemia had a higher ejection fraction at rest and at peak bicycle exercise compared with patients without daily life ischemia, but there were no other differences in peak hemodynamic or catecholamine responses to exercise. The presence of ST segment depression during routine daily activities was best predicted by ST segment depression during mental or bicycle exercise stress, although ST segment depression was rare during mental stress. CONCLUSIONS: Patients with daily life ischemia exhibit a heightened generalized response to mental stress. ST segment depression in response to mental or exercise stress is more predictive of ST segment depression during routine daily activities than other laboratory-based ischemic markers. Therapeutic management strategies might therefore focus on patients with these physiologic responses to stress and on whether lessening such responses reduces ischemia.

Activities of Daily Living↗
PubMed1999

Low hot pain threshold predicts shorter time to exercise-induced angina: results from the psychophysiological investigations of myocardial ischemia (PIMI) study.

OBJECTIVES: The purpose of this study was to test whether cutaneous thermal pain thresholds are related to anginal pain perception. BACKGROUND: Few ischemic episodes are associated with angina; symptoms have been related to pain perception thresholds. METHODS: A total of 196 patients with documented coronary artery disease underwent bicycle exercise testing and thermal pain testing. The Marstock test of cutaneous sensory perception was administered at baseline after 30 min of rest on two days and after exercise and mental stress. Resting hot pain thresholds (HPTs) were averaged for the two baseline visits and divided into two groups: 1) average HPT <41 degrees C, and 2) average HPT > or =41 degrees C, to be clearly indicative of abnormal hypersensitivity to noxious heat. RESULTS: Patients with HPT <41 degrees C had significantly shorter time to angina onset on exercise testing than patients with HPT > or =41 degrees C (p < 0.04, log-rank test). Heart rates, systolic blood pressure and rate-pressure product at peak exercise were not different for the two groups. Resting plasma beta-endorphin levels were significantly higher in the HPT <41 degrees C group (5.9+/-3.7 pmol/liter vs. 4.7+/-2.8 pmol/liter, p = 0.02). Using a Cox proportional hazards model, patients with HPT <41 degrees C had an increased risk of angina (p = 0.03, rate ratio = 2.0). These differences persisted after adjustment for age, gender, depression, anxiety and history of diabetes or hypertension (p < 0.01). CONCLUSIONS: Occurrence of angina and timing of angina onset on an exercise test are related to overall hot pain sensory perception. The mechanism of this relationship requires further study.

Adult↗
PubMed1999

A thermal vascular test for distinguishing between patients with Raynaud's phenomenon and healthy controls. Raynaud's Treatment Study Investigators.

This study tested the reliability and validity of a diagnostic thermal vascular test (TVT) for patients with Raynaud's Phenomenon (RP). The TVT examined digital blood pressure responses to combined cooling and occlusion and was developed as part of the Raynaud's Treatment Study, a multicenter clinical trial comparing the efficacy of biofeedback and pharmacological treatment. A computerized system permitted efficient, accurate, and uniform testing at different geographical sites. A comparison of 199 patients with RP and 52 healthy controls is reported. The TVT showed a sensitivity of 79% and a specificity of 88%. Test-retest reliability was acceptable (r = .80). Addition of a psychological challenge failed to improve the discrimination between patients with RP and controls. The TVT separated patients with RP and controls as well as or better than existing tests and did so with enhanced ease of operation.

Diagnosis, Differential↗
PubMed1998

Heterogeneity among cardiac ischemic and anginal responses to exercise, mental stress, and daily life.

The objectives of this study were to compare and contrast indicators of ischemia in a well-characterized group of 196 patients with coronary artery disease, documented angiographically or by verified history of myocardial infarction, and a positive exercise test result. Myocardial ischemia occurs frequently in response to everyday stressors in patients with coronary artery disease. The Psychophysiological Interventions in Myocardial Ischemia study provides a unique opportunity to study neuroendocrine and psychological manifestations of ischemia. Patients with exercise-induced ischemia underwent exercise radionuclide ventriculography and electrocardiographic monitoring and 2 laboratory mental stressors (Speech and Stroop) after being withdrawn from cardiac medications. In addition, 48-hour ambulatory electrocardiograms were recorded during routine daily activities. Patients with a history of angina within the past 3 months reported angina during the bicycle or treadmill test with a much higher frequency than patients without such an anginal history (77% vs 26%). Ejection fraction (EF) responses to the Stroop test were abnormal in 48% of patients with an abnormal EF response to the Speech task, versus 17% in patients with a normal EF response (p <0.01). Seventy-six percent of patients had an abnormal EF response to bicycle exercise. Three indicators of ischemia (ST-segment depression, wall motion abnormality, and EF response) were compared during the same laboratory stressor and across different types of stress tests. Presence of the 3 indicators was only moderately associated during exercise, and only weak or nonsignificant associations occurred among the presence of the 3 ischemic markers during mental stress. Occurrence of the same ischemic markers was moderately associated between the 2 mental stress tasks, but few associations were found between the occurrence of the same ischemic marker during exercise and mental stress. There is a marked heterogeneity of responses to psychological and exercise stress testing using electrocardiography, ambulatory electrocardiography, or radionuclide criteria for ischemia during stress. The heterogeneity may be related to differences in the magnitude or types of physiologic responses provoked and to differences in the sensitivity and specificity of the different tests used to identify ischemia.

Aged↗
PubMed1997

Heart rate variability: origins, methods, and interpretive caveats.

Components of heart rate variability have attracted considerable attention in psychology and medicine and have become important dependent measures in psychophysiology and behavioral medicine. Quantification and interpretation of heart rate variability, however, remain complex issues and are fraught with pitfalls. The present report (a) examines the physiological origins and mechanisms of heart rate variability, (b) considers quantitative approaches to measurement, and (c) highlights important caveats in the interpretation of heart rate variability. Summary guidelines for research in this area are outlined, and suggestions and prospects for future developments are considered.

Animals↗
PubMed1996

Left ventricular, peripheral vascular, and neurohumoral responses to mental stress in normal middle-aged men and women. Reference Group for the Psychophysiological Investigations of Myocardial Ischemia (PIMI) Study.

BACKGROUND: The normal cardiovascular response to mental stress in middle-aged and older people has not been well characterized. METHODS AND RESULTS: We studied 29 individuals 45 to 73 years old (15 women, 14 men) who had no coronary risk factors, no history of coronary artery disease, and a negative exercise test. Left ventricular (LV) volumes and global and regional function were assessed by radionuclide ventriculography at rest and during two 5-minute standardized mental stress tasks (simulated public speaking and the Stroop Color-Word Test), administered in random order. A substantial sympathetic response occurred with both mental stress tests, characterized by increases in blood pressure, heart rate, rate-pressure product, cardiac index, and stroke work index and rises in plasma levels of epinephrine and norepinephrine but not beta-endorphin or cortisol. Despite this sympathetic response, LV volume increased and ejection fraction (EF) decreased secondary to an increase in afterload. The change in EF during mental stress-varied among individuals but was associated positively with changes in LV contractility and negatively with baseline EF and changes in afterload. EF decreased > 5% during mental stress in 12 individuals and > 8% in 5; 3 developed regional wall motion abnormalities. CONCLUSIONS: Mental stress in the laboratory results in a substantial sympathetic response in normal middle-aged and older men and women, but EF commonly falls because of a concomitant rise in afterload. These results provide essential age- and sex-matched reference data for studies of mental stress-induced ischemia in patients with coronary artery disease.

Aged↗
PubMed1981

Enhancement of cortical evoked potentials by high atmospheric pressures of helium.

Adult guinea pigs with electrodes chronically implanted in the optic chiasm (OC(, lateral geniculate nucleus (LGN), and visual cortex (CX) were compressed at 1 bar/min to 120 bars pressure in helium-oxygen. Body temperature was controlled to within +/- 1 degree C, CO2 was removed by a soda-lime absorbent. Electrical stimuli (50 microA, 0.05 msec) were delivered to the OC at 9.6/sec at 10 bar intervals, with pressure held constant. Pressure caused only negligible changes inthe amplitudes of pre- and postsynaptic components of potentials in the LGN. Amplitudes of evoked potentials in the CX increased approximately linearly with pressure, reaching values of up to 300% above normobaric. Latencies did not change independently of temperature. Excitability of nerve fibers changed very little, but intracortical synaptic transmission was substantially enhanced. Differences in the effects of elevated helium pressure at the LGN and CX may be attributed to differences in organization of local circuits.

Animals↗
PubMed1980

Correspondence of brain and rectal temperatures of guinea pigs in helium environments.

Brain and rectal temperatures were measured in guinea pigs exposed to helium-oxygen environments at pressures as high as 50 bars. Very high correlations (r = .856, P less than 0.001) between the two values were observed, with an average difference of 0.47 degrees C (computed SD = 0.31). Brain temperature was usually higher than rectal. At a given ambient temperature, heat loss at 50 bars was more rapid than at 20 bars, which supports existing data for lower pressures. At 50 bars, normal equilibrium temperatures (approximately equal to 39 degrees C) could be maintained only if ambient temperature was in the vicinity of 35 degrees C. Lower ambient temperatures resulted in lower equilibrium temperatures. Between 33 and 39 degrees C, brain temperature can be predicted from rectal temperature, with an error of about 0.5 degree C.

Animals↗
PubMed1979

Spinal cord seizures elicited by high pressures of helium.

Rats with complete spinal transections were compressed in helium-oxygen to 120 bars. Tremors and increased EMG activity in limbs rostral as well as caudal to the lesions were observed beginning at 30 bars. Spinal seizures occurred at 95 bars, similar to cortical seizure thresholds of intact rats. Denervated limbs remained flaccid throughout the dives. No rostro-caudal progression of symptoms was evident in normal animals, but fluctuation of symptoms with increasing pressure was frequently observed. These findings are consistent with the hypothesis that the effects of pressure on aggregates of neurons exceed those on isolated components.

Animals↗
PubMed1979

Responses of retinal and visual pathway potentials of the guinea pig to nitrogen and helium at high pressure.

Electroretinographic, optic chiasm, and visual cortex potentials were monitored in the awake guinea pig as nitrogen pressures were raised to 16 ATA and held for 30 min. Pressurization to 90 ATA with helium in 10-ATA increments followed. We sought to (a) quantify the depressant effect of nitrogen on the retina as compared to the central visual pathway, and (b) to test for pressure reversibility. The electroretinogram was reduced approximately 15%, the chiasm potential by 15%, and the cortical response by 32% in 16 ATA nitrogen, and latent periods for the three signals increased an average of 5-8%. Helium at pressure did not restore the amplitude of the electroretinogram or optic chiasm response, but the visual cortex potential returned to control levels near 90 ATA total pressure. Reversal of the nitrogen-induced latency increases by helium was partially effective up to 40 ATA. Control latent periods were not reached. Further attenuation of the electroretinogram and chiasm response amplitudes, and increased latencies of all signals were observed at 50-90 ATA.

Action Potentials↗
PubMed1978

Effect of cerebellar ablation on the high pressure nervous syndrome in rats.

To evaluate the interaction between high pressure nervous syndrome (HPNS) seizures and cerebellar integrity, seizure threshold pressure (Pc) of normal rats was compared with that of rats sustaining cerebellar ablation two weeks prior to exposure to 136 ATA in a helium-oxygen atmosphere. All rats exhibited severe HPNS symptoms which culminated in seizures. Pc was reduced in cerebellectomized animals, and the number of seizure episodes increased twofold, but the average duration of seizure episodes was unchanged. The spike-and-wave pattern in the electroencephalogram remained a prominent feature in both groups.

Animals↗
PubMed1977

Cerebellar and cerebral electroencephalogram during the high pressure nervous syndrome (HPNS) in rats.

Electroencephalographic activity of the frontal cortex, cerebellar vermis, and superior vestibular nucleus was recorded in awake rats during the high pressure nervous syndrome (HPNS) by means of permanently implanted electrodes. Power-spectrum analysis revealed a decline in the faster frequencies and an increase in the slow frequences as the seizure end-point was approached. Effects of compression to 4500 fsw varied from severe tremor and myoclonic jerks to status epilepticus, with seizures occurring at an average depth of 3560 fsw. In all animals, multifocal-spiking activity progressed in severity with increasing depth. The predominant seizure pattern observed was a spike and slow-wave pattern reminiscent of absence seizures. Initial evidence of generalized seizure activity was equally divided between the cerebellum and cortex. It is concluded that the cerebellum participates in HPNS seizures. Possible evolution of the syndrome by loss of Purkinje cell inhibitory influence on subcortical sites that modulate cortical excitability is discussed.

Animals↗