Don't fence me in.

There are many applications of applied psychophysiology. Some are relevant to AAPB's interests, some are not. However, in no case should we exclude them from our purview merely by defining them out of our existence.

An historical and critical review of the articles on blood pressure published in Psychosomatic Medicine between 1939 and 1997.

Between 1939 and 1997, there have been 59 volumes of Psychosomatic Medicine. Over this period there were 200 articles dealing with blood pressure. About 90% of these were concerned with high blood pressure. This article reviews all of these papers both from an historical perspective and critically. Although there has been a significant growth in the rate of articles published since 1939, there has always been a strong interest in the nature of hypertension, particularly the roles of affects and emotions in the natural history of the disease. For example, volume 1, number 1 of the Journal includes a symposium on high blood pressure in which Franz Alexander stated his well-known hypothesis that the chronic inhibition of rage plays a causal role in the production of hypertension. In various forms, the notion that anger is an important mediator of hypertension has neither been proved nor abandoned. One major conclusion drawn from this review is that the current research on high blood pressure is drifting somewhat aimlessly. It has become preoccupied with demonstrations that various stimuli or situations (usually characterized as stresses) can acutely raise blood pressure. Despite this focus, neither the necessary nor the sufficient conditions for labeling a stimulus as stress has ever been agreed upon. Likewise, there have been many demonstrations of an iatrogenic effect on blood pressure, but neither the behavioral mechanisms underlying this effect nor the strategies for eliminating it have been explicated. Finally, this article identifies several areas where it would be useful to review and integrate current knowledge. Hopefully, such integrations could play a significant role in focusing and shaping future research and clinical practice.

Central neural correlates of learned heart rate control during exercise: central command demystified.

To identify the brain areas involved in central command, four monkeys were trained to attenuate the tachycardia of exercise while different brain sites affecting heart rate (HR) were simultaneously stimulated electrically. Among 24 brain sites located mostly in the limbic structures, we have identified four types of control systems that mediate cardiovascular and motor behavior during exercise. One system increases HR equivalently during both exercise and operantly controlled HR, whereas another increases HR during both tasks and abolishes operant HR control. In the third system, the effect of brain stimulation on HR is attenuated during exercise and during exercise with operantly controlled HR. The fourth system increases HR in both tasks, but its effect is significantly attenuated during operant HR control. We believe that this last system, which includes the mediodorsal nucleus, nucleus ventralis anterior, and cingulate cortex, plays a significant role in central command.

Heat loss during cold exposure in adult and aged C57BL/6J mice.

Metabolic heat production (MHP), colonic temperature (Tco), and nonevaporative (dry) heat loss were measured in ADULT and AGED C57BL/6J male mice during cold exposure. Dry heat loss was assessed as a differential temperature (Td) between incoming and outgoing air through the chamber for indirect calorimetry. The average Td during cold exposure normalized to surface area for ADULT mice was significantly higher than that for the AGED animals (0.0618 +/- 0.0003 degree C/cm2 and 0.0553 +/- 0.0005 degree C/cm2, respectively). Linear regression analysis showed that at the same Tco AGED mice showed lower values of Td normalized to surface area, indicating that at the same body temperature they were losing less heat than ADULT animals. It was concluded that age-related decline in cold tolerance in mice is not due to a lack of ability to reduce heat loss during cold exposure. On the contrary, AGED animals had lower heat loss in comparison with ADULT. We suggest that augmentation of heat conservation mechanisms is an adaptive response to diminishing cold-induced heat production.

Nonshivering thermogenesis during acute cold exposure in adult and aged C57BL/6J mice.

In C57BL/6J adult and aged mice, housed at room temperature (22.5 +/- 1 degrees C), we measured O2 consumption and CO2 production and calculated metabolic heat production under conditions of anesthesia and myorelaxation during acute cold stimulation when body temperature was lowered 7.5 degrees C below control level. An independent group of mice was subjected to a three hour partial physical restraint at 6 degrees C and concentration of uncoupling protein (thermogenin) was measured in interscapular brown adipose tissue mitochondria at different times after cold exposure. Heat production under anesthesia and myorelaxation was about 57-66% lower than in nonanesthetized conditions, but increased significantly during cold stimulation in both age groups. Under anesthesia and myorelaxation before and during cold stimulation aged mice produced about 20% more heat than adult mice. Because in these experiments all sources of facultative thermogenesis, except nonshivering, were suppressed by anesthesia and myorelaxation, and because brown adipose tissue is the major source of nonshivering thermoproduction, we concluded that aged mice housed at room temperature have an increased thermogenesis in brown adipose tissue. This conclusion was also supported by the finding that the concentration of uncoupling protein measured in the mitochondria of brown adipose tissue after single cold exposure was significantly higher in aged than in adult mice. Therefore, we propose that the lower, cold-induced, heat production typically observed in nonanesthetized aged mice may reflect reduced thermogenic capacity of skeletal muscles. While aged mice have less brown adipose tissue than adult animals, the remaining brown adipose tissue may compensate by increasing the concentration of uncoupling protein.

Overnight heart rate and cardiac function in patients with dual chamber pacemakers.

Animal data indicate that chronic, overnight pacing at normal evening heart rates impairs cardiac function. We examined the relationship of pacing rate and cardiac function in nine patients with dual-chamber pacemakers. We investigated two, 3-week pacing regimens (80 and 50 ppm: DDD mode) in a cross-over design. Doppler echocardiograms were performed at 1700 hours (PM) and 0600 hours (AM) at the end of each regimen. Ventricular function and preload decreased overnight (PM vs AM) with both pacing regimens. Compared to the morning values, the ratio of preejection to ejection time (PEP/ET) rose (0.43 vs 0.46), while the mean velocity of circumferential fiber shortening (Vcf) fell (1.16 cm/s vs 1.11 cm/s). Stroke volume (SV) (61 mL vs 53 mL) and ejection fraction (EF) also fell (0.56 vs 0.53) in the morning. End-diastolic volume (EDV) (94 mL vs 88 mL) decreased in the morning, as did the ratio of passive to active filling (E/A) (1.06 vs 0.96). Isovolumic relaxation time (91 ms vs 101 ms) increased overnight at both pacing rates. Systolic function decreased at 80 ppm relative to 50 ppm at both times of day. SV fell (54 mL vs 61 mL), while both EDV (92 mL vs 90 mL) end-systolic volume (ESV) increased (43 mL vs 40 mL). Contractility measured by Vcf (1.09 cm/s vs 1.18 cm/s) and PEP/ET (0.49 vs 0.41) was reduced at 80 ppm. The heart needs to rest at night by slowing its rate of contraction. Pacing at 80 ppm impairs systolic and diastolic ventricular function compared to 50 ppm. Longer term consequences of ostensibly physiological pacing rates merit inquiry, particularly in those with preexisting cardiac dysfunction.

Sympathetic outflow to interscapular brown adipose tissue in cold acclimated mice.

C57BL/6J male mice were subjected to a cold acclimation procedure which consisted of three consecutive cold stress tests: 3-h partial restraint at 6 degrees C at 2-wk intervals. During the week following the last cold stress test, each animal previously subjected to the cold acclimation procedure, and an additional group of naive mice (animals that never had been exposed to an environment below room temperature) were anesthetized with urethan, paralyzed with vecuronium bromide, artificially ventilated, and subjected to cold stimulation for approximately 16 min. Electrical impulse activity from one of the fine sympathetic nerves entering the interscapular brown adipose tissue was recorded before and during cold stimulation, until body temperature dropped 8 degrees C below control level. Sympathetic outflow increased significantly during cold stimulation in all mice. Animals that did not achieve cold acclimation in three repeated cold stress tests (they demonstrated less cold tolerance in the last test) had lower sympathetic nervous outflow to brown adipose tissue at room temperature and during cold stimulation than mice that had achieved cold acclimation. In fact, sympathetic nervous outflow to brown adipose tissue in mice that had failed to show cold acclimation was similar to that of naive mice. These findings indicate that the sympathetic nervous system plays a primary role in cold acclimation.

Mobility in older patients with hip fractures: examining prefracture status, complications, and outcomes at discharge from the acute-care hospital.

The purpose of this study was to examine the relationships among prefracture status, development of complications, mobility outcomes at discharge, and disposition at discharge. We singled out a case series of consecutive noninstitutionalized elderly persons hospitalized for hip fracture (ICD 820.0-820.9) at two Baltimore hospitals during 1992-1993. Data were abstracted from the medical records for the following variables: sociodemographic information, prefracture status, selected medical conditions, injury and surgical treatment, complications, functional mobility and assistance needed at discharge, and disposition. Factors associated with four complications were identified from multiple logistic regression analyses. (a) Prefracture needs for assistance with activities of daily living (ADL), and age > or = 80, were associated with the development of pressure ulcers. (b) Male gender and prefracture urinary incontinence (UI) were associated with pneumonia. (c) Prefracture UI and weight-bearing status were associated with UI after removal of an indwelling catheter. (d) Age > or = 80 was associated with urinary retention. The amount of assistance needed for mobility tasks at discharge was associated with prefracture need for assistance with ADLs, gender, weight-bearing status, and hospitals with shorter lengths of stay and fewer physical therapy sessions. Patients who were older and had shorter lengths of stay and less physical therapy were more likely to go to another health facility than directly home. Prefracture status (ADL, prefracture UI) was significantly associated with the development of complications. Prefracture needs for assistance with ADL and complications were associated with mobility outcomes at discharge. These prefracture factors have an effect on outcomes and need to be addressed in the development of critical pathways for case treatment. Specific protocols for subgroups of patients may need to be designed and evaluated.

Urinary incontinence: a program that works.

Using a simple and inexpensive intervention, improvement in dryness was apparent by the first week of the study. More importantly, results were achieved by changing staff behavior, rather than residents' behavior.

Sympathetic nervous activity to brown adipose tissue increases in cold-tolerant mice.

Brown adipose tissue (BAT) is thought to be responsible for increased heat production in cold-acclimated rodents. We measured sympathetic nerve activity (SNA) in interscapular BAT (IBAT) during cold stimulation in cold-acclimated C57BL/6J mice (ACCLI). Cold acclimation was achieved (cold tolerance was increased) by repeated exposure to cold stress every other week for 3 weeks. We compared SNA in these animals with SNA in mice that had no previous cold stress experience (naive). During the test, mice were anesthetized by urethane and isoflurane and were paralyzed with vecuronium bromide. Sympathetic nerve activity was recorded directly from one of the fine nerves to IBAT. The animal's body caudal to the pelvic area was covered with a plastic bag containing a slurry of ice water to decrease colonic temperature 7 degrees C below control level, which took approximately 20 min. Interscapular BAT-SNA increased during cold stress in both groups, but ACCLI mice had higher IBAT-SNA during cold stress than naive mice. These findings confirmed the hypothesis that during the acute cold exposure, cold-acclimated mice have greater sympathetic outflow to BAT adipocytes.

The effects of changing prompted voiding schedules in the treatment of incontinence in nursing home residents.

OBJECTIVE: To determine the effects of different prompted voiding schedules on urinary incontinence on a continence unit (CU) and the maintenance of benefits on normal nursing units. DESIGN: Multiphase study with both intra- and inter-subject comparisons. PARTICIPANTS: Subjects were 41 consenting incontinent nursing home residents. Based on clinical criteria, subjects were assigned to one of four treatment groups that varied as to the schedule of prompted voiding received. MEASUREMENT: The study used chart review, Katz ADL, and MMSE. Urologic status, self-initiated toileting, urine volumes voided, and incontinence assessed by pad/pants checks were measured by research nurses. Baseline pad check data were collected on residents' normal nursing units. Residents were transferred to the CU where baseline measurement was repeated, and the effects of different prompted voiding schedules were then assessed. Indigenous staff were trained to use prompted voiding, and nurse supervisors were instructed in special procedures for enhancing maintenance of the intervention. Residents were returned to their normal units and the maintenance of improvements in continence status was assessed at 2 weeks and 3 months post-CU discharge. RESULTS: One of the four groups showed significant improvement on the CU in response to the 2-hour schedule; two groups improved on the less intensive 3-hour schedule (P < 0.05). Two groups maintained this improvement on their normal nursing units (P < 0.05); one group showed a non-significant trend toward improvement. Self-initiated toileting decreased (P < 0.05) and volume voids in an appropriate receptacle increased (P < 0.05) during training. CONCLUSIONS: Prompted voiding is an effective treatment for urinary incontinence, and a less intensive 3-hour schedule may be superior to the standard 2-hour schedule for some residents. These improvements in dryness can be maintained by normal nursing home staff if formal staff management procedures are utilized by nurse supervisors.

Aged C57BL/6J mice respond to cold with increased sympathetic nervous activity in interscapular brown adipose tissue.

Aged, male C57BL/6J mice produce less heat than adults during cold, which may lead to a reduced ability to maintain core temperature, but the underlying mechanisms of the decreased heat production in aged mice are still unclear. We measured sympathetic nervous activity (SNA) to interscapular brown adipose tissue (IBAT) in aged mice and compared this activity with that of adults. Mice were anesthetized by urethane and isoflurane, and SNA was recorded from one of the fine nerves to IBAT. The animal's body caudal to the pelvic area was covered with a plastic bag containing iced-water to decrease colonic temperature 7 degrees C below control over 20 minutes. SNA to IBAT (IBAT-SNA) increased during cold in both groups, but aged mice had higher IBAT-SNA before and during cold. These findings indicate that neither the ability of aged mice to detect cold nor their ability to generate sympathetic outflow to BAT is deficient.

Autonomic behavior.

This article summarizes a body of work which collectively shows that autonomic responses meet the criteria for behavior. They can be modified reliably through the systematic use of antecedent (cues) and consequent (contingencies) stimuli. This means that autonomic responses, which are usually characterized as elicited reflexes, can be learned responses (viz., behaviors). This review cites a number of experimental and clinical studies in which autonomic learning has been shown to occur and to have clinical importance. Of special interest to gerontologists are the clinical studies which show that incontinent and hypertensive elderly patients can be trained to normalize their pathognomic responses.

Role of postural status in the nocturnal hemodynamic patterns of nonhuman primates.

We compared the nocturnal hemodynamic patterns of seven tethered monkeys (Macaca mulatta) with those of seven chaired animals to determine whether the overnight changes are comparable in the two conditions. In both groups, we found a consistent hemodynamic pattern characterized by an overnight fall in cardiac output and central venous pressure and a rise in total peripheral resistance that maintained blood pressure homeostasis. The pattern of overnight change occurred despite major differences in response levels: cardiac output and central venous pressure were significantly elevated, and total peripheral resistance was significantly reduced at all times (from 1800 to 1200 h the following day) in the chaired animals relative to the tethered animals. This difference was probably due to an expanded plasma volume in the chaired animals, because stroke volume was also significantly elevated. Because the nocturnal hemodynamic pattern occurred under both conditions, it is likely that it is a stable biologic effect, which is probably related to an overnight loss in fluid volume that is not replaced in animals that sleep throughout the night.

Morning increase in whole blood viscosity: a consequence of a homeostatic nocturnal haemodynamic pattern.

In a series of studies, we have shown that in non-human primates there is a consistent overnight fall in cardiac output and central venous pressure, and a rise in total peripheral resistance. This haemodynamic pattern is associated with a higher haematocrit level in the morning suggesting that these changes in the circulation are homeostatic adjustments to a nighttime fall in plasma volume. The present study was designed to test the hypothesis that in the morning whole blood viscosity also is higher. Whole blood viscosity was measured at shear rates of 450, 225, 90, 45, and 22.5 s-1 in each of six monkeys, on four occasions, at 2-week intervals, at 17.00 and 09.00 h the next morning. The average haematocrit was 4.2% higher in the morning than in the previous evening (P < 0.01). Viscosity decreased monotonically at progressively higher shear rates but was always significantly higher in the morning than in the evening (P < 0.01 at all shear rates). When viscosity was adjusted by covarying for haematocrit level, the morning/evening differences became non-significant. However, the morning/evening differences in linear trend of shear stress as a function of shear rate persisted. These findings add further support to our hypothesis that the nocturnal haemodynamic pattern in non-human primates is related to a reduction in plasma volume, and they also suggest that the morning rise in haematocrit is a major contributing factor to the elevated viscosity.

Effect of nocturnal atrial demand cardiac pacing on diurnal hemodynamic patterns.

Heart rate (HR), stroke volume (SV), intra-arterial blood pressure, and central venous pressure were recorded on a beat-to-beat basis, 18 h/day (1800-1200 h the following day), for approximately 2 mo in four monkeys (Macaca mulatta). Cardiac output, left ventricular work, and total peripheral resistance were derived from these primary measurements. During the 1st mo we measured these parameters under control conditions, and during the 2nd mo the animals were studied while HR was paced by atrial demand pacing sufficient to prevent the normal nocturnal fall in HR (approximately 10 beats/min above the fastest hourly average rate recorded during the control condition). The main hypothesis of this study was that when HR is prevented from falling, SV, which normally does not fall overnight, would fall; this hypothesis was confirmed. In addition, we observed that, during the period of pacing, relative to the control period, SV was approximately 14% greater during the early evening and 4% lower during the early morning; total peripheral resistance was similar during the early evening but was 13% higher by morning. Throughout the night, systolic pressure was approximately 4% greater, diastolic pressure was 17% higher, central venous pressure was 43% greater, and left ventricular work was 27% higher. These findings show that when HR is prevented from falling overnight by atrial demand pacing, even to a relatively modest degree, there can be very significant sustained changes in cardiovascular function.

Systematic nocturnal atrial demand pacing results in high-output heart failure.

Beat-to-beat parameters of heart rate (HR), intra-arterial blood pressure (BP), central venous pressure, and derived indexes of cardiac output and total peripheral resistance were recorded 18 h/day (from 1800 to 1200 h the following day) in four monkeys (Macaca mulatta) during 20 control days followed by 20 days of atrial demand pacing. The pacing rate was set at approximately 10 beats/min above the fastest hourly average HR recorded during the control period, i.e., sufficient to prevent the normal nocturnal fall in HR. Nocturnal pacing resulted in progressive weekly increases in central venous BP and arterial BP. Analyses of levels and diurnal trends in hemodynamic parameters and cardiac function curves across consecutive 5-day periods of nocturnal pacing revealed a hemodynamic pattern characteristic of high-output heart failure, which progressively increased (week by week) during the early morning hours (0500-0700). Sustained elevated left ventricular work resulting from the prevention of a nocturnal fall in HR may have been responsible for the reduction in cardiac function seen in this experimental model.

Overnight increases in haematocrit: additional evidence for a nocturnal fall in plasma volume.

Our previously published studies with monkeys describe a characteristic nocturnal haemodynamic pattern consisting of a monotonic decline in cardiac output and central venous pressure, and a concomitant rise in total peripheral resistance. These findings led us to hypothesize that there is a reduction in total plasma volume during the night. Since a fall in plasma volume should cause an increase in haemoglobin and plasma protein concentration, we designed this experiment to test the hypothesis that haematocrit levels would be significantly greater in the morning than in the evening. In a study of five monkeys, the levels of haematocrit were measured at 1700 h and at 0900 h the next morning for 14 days. The average morning haematocrit levels were 6.5% higher than the average evening values. Lower plasma volume and possibly greater blood viscosity could contribute to the pathophysiology of the morning increase in the incidence of 'silent' ischaemia and catastrophic vascular events such as sudden cardiac death, myocardial infarctions and strokes in man.

Urinary incontinence: an augmented prompted void approach.

Continence improves from 44.7% dryness at baseline to 54.7% at the end of treatment, an improvement of 22%, or about one incontinent episode per day. Urinary incontinence is improved in cognitively impaired residents by augmenting the prompted voiding procedure with a bellpad. Bladder behavior changes with behavioral treatment strategies, because the volume voided into an appropriate receptacle increased an average of 26 mL per 2 hours. Reimbursement policies should not exclude treatment of the severely cognitively impaired nor the immobile in nursing homes.

Responses of sympathetic nerves innervating blood vessels in interscapular, brown adipose tissue and skin during cold stimulation in anesthetized C57BL/6J mice.

The effect of cold stimulation on the activity of sympathetic nerves running along blood vessels in interscapular, brown adipose tissues (IBAT) and skin overlying IBAT was examined in 15, urethane-anesthetized, artificially ventilated, C57BL/6J mice. Cold stimulation was applied caudal to the pelvic area using a plastic bag containing iced water. The stimulation of 14-16 min duration reduced core temperature measured at the esophagus or muscle near the esophagus by approximately 4 degrees C from a control temperature of about 38 degrees C. The stimulation decreased the activity of the nerve branches to IBAT, while it increased the activity of the nerve branches to skin. Blood flow in the IBAT increased significantly following the stimulation; however, this effect was abolished by the denervation. These findings suggest that the sympathetic innervation of the blood vessels in the IBAT plays a major role in thermoregulation against cold by decreasing the vascular tone and thus increasing the IBAT blood flow. An increase in the IBAT blood flow would facilitate the dissipation of heat from the IBAT to various organs as well as the supply of energy stuffs to the IBAT.