Heart rate perception was assessed in two sets of trials by having subjects set an intermittent visual pulse to match their heart rates. Just prior to matching subjects were required to either hyperventilate, hypoventilate or breathe normally to encourage a range of cardiac levels. Preceding each set of perception trials, bidirectional heart rate control was attempted. While one group of subjects received no exteroceptive feedback throughout, the other received continuous visual heart rate feedback on the second occasion. The data provided evidence of heart rate perception (as indexed by the correlation between interbeat and interpulse intervals) in a substantial number of instances. Further, perception was reliably associated with initial externally unaided cardiac control, although only in the increase direction. However, while the introduction of feedback tended to enhance cardiac control albeit only acceleratory control, no parallel effect was observed for perception. Analysis of interbeat and interpulse intervals in the different conditions of the matching task suggested that a real discrimination was probed by the procedure employed, but implied that respiratory cues afforded the basis for discrimination.

Adolescent↗

PubMedDate not supplied

Cardiac, respiratory and metabolic changes during static exercise and voluntary heart rate acceleration.

Various ventilatory and metabolic parameters were monitored in 12 subjects while they performed each of three tasks: Voluntary cardiac acceleration with the aid of continuous heart rate feedback; a static hand-grip exercise at 1/3 maximum voluntary contraction; and a combined task involving both voluntary acceleration and exercise. Task order was counterbalanced across subjects and there were six 30 sec trials of each task. While reliable cardiac accelerations were recorded throughout, they were substantially greater with the combined task. This confirmed previous findings attesting that individuals can voluntarily elevate heart rate above levels induced by standard physical loads. However, the pattern of results for oxygen consumption and carbon dioxide production, with the most substantial increase in both also occurring for combined voluntary acceleration and exercise, suggested that the cardiac elevations superimposed on exercise levels were largely non-specific, i.e. they involved additional energy expenditure. Respiration volume increased during the performance of all three tasks, with the greatest increase again occurring in the combined tasks. The precise respiratory adjustments, in terms of rate and tidal volume, varied subtly among tasks; while all three tasks produced a rise in respiration rate, only the combined task increased tidal volume.

Adult↗

PubMedDate not supplied

Is serum gentamicin level a good predictor of graft injury in intestinal transplantation?

INTRODUCTION: Following intestinal transplant (SBT), the early diagnosis and treatment of rejection is a major management aim. The diagnosis of rejection is based on histology of stomal biopsies. Oral gentamycin (2.5 mg/kg) was used for selective decontamination of the digestive system. Our hypothesis was that gentamycin might be absorbed in the presence of graft dysfunction. AIM: Our goal was to assess the correlation between serum gentamycin level and the health of the intestinal graft. SUBJECTS AND METHODS: Among 33 SBT performed from 1993 to 2005, serum gentamycin levels were performed once weekly or more often when there was a suspicion of rejection. All data were analyzed retrospectively. RESULTS: Adequate trough levels were achieved for only 23 patients, six of whom had histologically proven rejection and only one did not have a raised gentamycin content. Five patients with raised levels but no rejection included two with severe intestinal ischemia and three with bowel obstruction/ileus. Four of the five patients required laparotomies. CONCLUSION: We concluded that in our study raised serum gentamycin levels were a good predictor of rejection or significant injury to the graft.

Biomarkers↗

PubMedDate not supplied

An historical context for behavioral models of hypertension.

OBJECTIVE: The purpose of this study is provide an historical context for current behavioral models of hypertension. METHODS: A selective sample of the cardiovascular reactivity literature was reviewed, from 1932 to present. RESULTS: In the earliest model, cardiovascular reactivity was regarded as a marker of disease risk; however, in later models, reactivity came to be viewed as a causal influence in the development of hypertension. As the models evolved, the underlying assumptions changed. Thus, the risk marker model assumed that cardiovascular responses to stress were a stable, generalized characteristic of the individual, and therefore the eliciting stimuli were arbitrary. The later models, however, assume that the nature of the eliciting stimulus is a determinant of the cardiovascular response. We describe the increasing complexity of the four models, and contrast their underlying assumptions and the implications of these assumptions. CONCLUSION: We provide an overview of study designs and variables that should be incorporated into studies seeking to understand the ways in which cardiovascular responses to stress may influence the development of hypertension.

Blood Pressure↗

PubMedDate not supplied

Mortality and quality of life 12 months after myocardial infarction: effects of depression and anxiety.

OBJECTIVE: The purpose of this study was to determine the impact of symptoms of depression and anxiety on mortality and quality of life in patients hospitalized for acute myocardial infarction (MI). METHODS: The Beck Depression Inventory and the State-Trait Anxiety Inventory were completed by 288 patients hospitalized for MI. Twelve-month survival status was ascertained, and quality of life among survivors was assessed at 12 months using the Dartmouth COOP charts. RESULTS: Thirty-one (10.8%) patients died, 27 of cardiac causes, during the 12-month follow-up. Symptoms of depression and anxiety predicted neither cardiac nor all-cause mortality. Severity of infarction and evidence of heart failure predicted both cardiac and all-cause mortality. The same findings emerged from supplementary analyses of data from patients who died after discharge from the hospital. Symptoms of depression and anxiety, measured at entry, predicted 12-month quality of life among survivors, as did gender, partner status, employment status, living alone, previous frequency of exercise, and indices of disease severity (Killip class and Peel Index). In a multiple regression model in which all of these variables were entered, initial depression scores provided the best independent prediction of quality of life, although living alone, severity of infarction, and state anxiety also entered the model. CONCLUSIONS: Symptoms of depression and anxiety did not predict either cardiac or all-cause mortality after MI, but they did predict quality of life among those who lived to 12 months.

Adult↗

PubMedDate not supplied

Blood pressure reactions to acute psychological stress and future blood pressure status: a 10-year follow-up of men in the Whitehall II study.

OBJECTIVE: The aim of this study was to examine whether blood pressure reactions to mental stress predicted future blood pressure and hypertension. METHODS: Blood pressure was recorded at an initial medical screening examination after which blood pressure reactions to a mental stress task were determined. A follow-up screening assessment of blood pressure and antihypertensive medication status was undertaken 10 years later. Data were available for 796 male public servants, between 35 and 55 years of age upon entry to the study. RESULTS: Systolic blood pressure reactions to mental stress were positively correlated with follow-up screening systolic blood pressure and to a lesser extent, follow-up diastolic pressure. In multivariate tests, by far the strongest predictors of follow-up blood pressures were initial screening blood pressures. In the case of follow-up systolic blood pressure, systolic reactions to stress emerged as an additional predictor of follow-up systolic blood pressure. With regard to follow-up diastolic blood pressure, reactivity did not enter the analogous equations. The same outcomes emerged when the analyses were adjusted for medication status. When hypertension at 10-year follow-up was the focus, both systolic and diastolic reactions to stress were predictive. However, with correction for age and initial screening blood pressure, these associations were no longer statistically significant. CONCLUSIONS: The results of this study provide modest support for the hypothesis that heightened blood pressure reactions to mental stress contribute to the development of high blood pressure. At the same time, they question the clinical utility of stress testing as a prognostic device.

Acute Disease↗

PubMedDate not supplied

Socioeconomic differentials in mortality: evidence from Glasgow graveyards.

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Age Factors↗

PubMedDate not supplied

Nosology of "Pickwickian syndrome".

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Humans↗