New tree-ring data from Canadian boreal and hemi-boreal forests provide insight for improving the climate sensitivity of terrestrial biosphere models

Understanding boreal/hemi-boreal forest growth sensitivity to seasonal variations in temperature and water availability provides important basis for projecting the potential impacts of climate change on the productivity of these ecosystems. Our best available information currently comes from a limited number of field experiments and terrestrial biosphere model (TBM) simulations of varying predictive accuracy. Here, we assessed the sensitivity of annual boreal/hemi-boreal forest growth in Canada to yearly fluctuations in seasonal climate variables using a large tree-ring dataset and compared this to the climate sensitivity of annual net primary productivity (NPP) estimates obtained from fourteen TBMs. We found that boreal/hemi-boreal forest growth sensitivity to fluctuations in seasonal temperature and precipitation variables changed along a southwestern to northeastern gradient, with growth limited almost entirely by temperature in the northeast and west and by water availability in the southwest. We also found a lag in growth climate sensitivity, with growth largely determined by the climate during the summer prior to ring formation. Analyses of NPP sensitivity to the same climate variables produced a similar southwest to northeast gradient in growth climate sensitivity for NPP estimates from all but three TBMs. However, analyses of growth from tree-ring data and analyses of NPP from TBMs produced contrasting evidence concerning the key climate variables limiting growth. While analyses of NPP primarily indicated a positive relationship between growth and seasonal temperature, tree-ring analyses indicated negative growth relationships to temperature. Also, the positive effect of precipitation on NPP derived from most TBMs was weaker than the positive effect of precipitation on tree-ring based growth: temperature had a more important limiting effect on NPP than tree-ring data indicated. These mismatches regarding the key climate variables limiting growth suggested that characterization of tree growth in TBMs might need revision, particularly regarding the effects of stomatal conductance and carbohydrate reserve dynamics.

Differential association of insulin resistance with cognitive and somatic symptoms of depression

AIM

To examine the associations of depressive symptoms with insulin resistance, evaluating somatic and cognitive depressive symptoms separately.

METHODS

A total of 328 individuals (mean age 60 years) referred for exercise stress testing, taking part in the Mechanisms and Outcomes of Silent Myocardial Ischemia study, completed the Beck Depression Inventory II. A fasting venous blood sample was collected for assessments of insulin and glucose level; the HOMA-IR (homeostatic model assessment of insulin resistance) was calculated. In principal component analysis, Beck Depression Inventory II items were forced to load onto two components (somatic and cognitive depressive symptoms). Adjusting for age, sex, BMI, medication use, smoking, physical activity, diabetes and cardiovascular disease, general linear model analyses were conducted to examine the associations between the components and log HOMA-IR .

RESULTS

Principal component analysis showed that nine items loaded onto a cognitive depressive symptoms component and 10 items loaded onto a somatic depressive symptoms component. When examined separately, both components were significantly associated with log HOMA-IR however, when including both components simultaneously in the model, only somatic depressive symptoms remained significantly associated with log HOMA-IR. Back-transformed, a one-unit change in somatic depressive symptoms was associated with a 1.07 (95% CI 1.002, 1.14) change in HOMA-IR and a one-unit change in cognitive depressive symptoms was associated with a 1.03 (95% CI 0.97, 1.14) change in HOMA-IR.

CONCLUSION

Somatic depressive symptoms seem to be more strongly associated with insulin resistance than do cognitive depressive symptoms. Monitoring somatic depressive symptoms may be more appropriate than monitoring cognitive depressive symptoms among depressed individuals with high insulin resistance.

Detection of exercise-induced myocardial ischemia from symptomatology experienced during testing in men and women

BACKGROUND AND OBJECTIVES

To examine the capacity of angina and related symptoms experienced during exercise-stress testing to detect the presence of ischemia, controlling for other clinical factors.

METHOD

The authors undertook a prospective study of 482 women and 425 men (mean age 58 years) undergoing exercise stress testing with myocardial perfusion imaging. One hundred forty-six women and 127 men reported chest pain, and of these, 25% of women and 66% of men had myocardial perfusion imaging evidence of ischemia during testing. The present article focuses on patients with chest pain during testing.

MAIN OUTCOME MEASURES

Outcome measures included chest pain localization, extension, intensity and quality, as well as the presence of various nonpain-related symptoms. Backward logistical regression analyses were performed separately on men and women who had experienced chest pain during testing.

RESULTS

Men who described their chest pain as 'heavy' were 4.6 times more likely to experience ischemia during testing (P=0.039) compared with other men, but this pain descriptor only slightly improved accuracy of prediction beyond that provided by control variables. In women, several symptoms added to the sensitivity of the prediction, such as a numb feeling in the face or neck region (OR 4.5; P=0.048), a numb feeling in the chest area (OR 14.6; P=0.003), muscle tension (OR 5.2; P=0.013), and chest pain that was described as hot or burning (OR 4.3; P=0.014).

CONCLUSIONS

A more refined evaluation of symptoms experienced during testing was particularly helpful in improving detection of ischemia in women, but not in men. Attention to these symptoms may favour timely diagnosis of myocardial perfusion defects in women.

The role of ischaemia and pain in the blood pressure response to exercise stress testing in patients with coronary heart disease

Silent myocardial ischaemia is a common phenomenon in patients with coronary heart disease. However, very little is known about the underlying mechanisms of silent ischaemia. One potential pathway that may contribute to this absence of pain is increased blood pressure. The main aim of the current study was to assess the associations among blood pressure, pain and ischaemia in patients undergoing a standard exercise stress test. We hypothesized that patients who experienced chest pain during exercise would have lower baseline and peak blood pressures compared to those who did not experience chest pain. A total of 1,355 patients (418 women) who underwent a single-photon emission computed tomography treadmill exercise stress test and had not experienced a cardiac event in the past 2 weeks participated in the current study. Myocardial perfusion defects were assessed at rest and during the stress challenge. Systolic blood pressure (SBP), diastolic blood pressure, heart rate (HR) and rate pressure product (RPP) were assessed during rest and at peak exercise. There were no main effects of either pain or ischaemia on the baseline cardiovascular variables. Peak exercise data revealed main effects of pain on SBP, RPP and HR, and main effects of ischaemia on SBP and RPP, controlling for age, sex, baseline level, medication status and cardiac history. These findings suggest that acute rather than chronic increases in blood pressure may be one mechanism to explain the phenomena of silent myocardial ischaemia in cardiac patients, and may potentially provide a target for future treatment strategies.

Treatment of long, diffuse, in-stent restenotic lesions with beta radiation using strontium 90 and sequential positioning "pullback" technique: procedural details and clinical outcomes

BACKGROUND

Long, diffuse, in-stent restenotic lesions have been problematic for many patients, necessitating the need for multiple repeat percutaneous coronary interventions (PCI). The need for repeat PCI has been significantly reduced in patients since the advent of vascular brachytherapy. In-stent restenosis resulting in long lesions (> 30 mm) presents even more of a challenge. The interventional injury length created during PCI is usually greater than 30 mm and the vascular brachytherapy systems available in most hospitals are 30 mm or 40 mm in length. The purpose of this paper is to define "pullback technique" and to report the Montreal Heart Institute (MHI) data to show that the pullback technique using the Novoste system seems to be a safe and effective method for using vascular brachytherapy to treat long, diffuse, in-stent restenotic lesions.

METHODS

We reviewed the database of patients enrolled in the Compassionate Use Registry between August 1999 and July 2000. The data are reported on 23 consecutive patients treated with the pullback technique.

RESULTS

The mean lesion length was 49.4 +/- 19.8 mm. Three patients (13%) underwent target vessel revascularization. Angiographic follow-up was obtained in 18 patients (78%). Seven patients (38.8%) showed angiographic restenosis (> 50% luminal re-narrowing). No aneurysms or zones of ectasia were noted.

CONCLUSION

This angiographic and clinical evaluation of the MHI Compassionate Use Registry data show the pullback technique to be safe from both a dosimetric and clinical point of view.

Sauna-induced myocardial ischemia in patients with coronary artery disease

PURPOSE

Sauna bathing is a popular recreational activity that is generally considered to be safe. However, there have been case reports of adverse cardiac events. We sought to determine whether sauna use caused myocardial ischemia in patients with coronary artery disease.

METHODS

Sixteen patients with proven coronary artery disease were submitted to three conditions (rest, exercise, and sauna bathing) with continuous electrocardiographic (ECG) monitoring and regular blood pressure measurements. During each condition, patients were injected with Tc-99 sestamibi followed by nuclear scintigraphic imaging. Perfusion defect scores were calculated in 15 patients.

RESULTS

Sauna bathing was well tolerated. There was a mean (+/- SD) increase in heart rate of 32% +/- 20% in the sauna (resting mean heart rate = 60 +/- 9 beats per minute vs sauna mean heart rate = 79 +/- 11 beats per minute, P <0.001) and a 13% +/- 6% drop in systolic blood pressure (resting mean systolic blood pressure = 142 +/- 14 mm Hg vs sauna mean systolic blood pressure = 123 +/- 15 mm Hg, P <0.001). There were no arrhythmias or ECG changes in the sauna. Compared with rest, there was significant ischemia during sauna bathing (average perfusion defect score at rest = -0.44 vs average sauna score = -0.93, P <0.001). The perfusion defect score in the sauna was worse than the resting score in 14 of the 15 patients. Sauna-associated perfusion defect scores were highly correlated with exercise-induced scores (R2 = 0.65, P <0.001).

CONCLUSION

In patients with stable coronary artery disease, sauna use is clinically well tolerated but is associated with scintigraphically demonstrated myocardial ischemia.

Effects of intracoronary beta-radiation therapy after coronary angioplasty: an intravascular ultrasound study

BACKGROUND

Endovascular radiation is emerging as a potential solution for the prevention and treatment of restenosis. Its effects on the morphology of unstented vessels cannot be determined by angiography and therefore require the use of intravascular ultrasound.

METHODS AND RESULTS

Through a 5F noncentered catheter for delivery of a 90Sr/Y source train, 12, 14, or 16 Gy at 2 mm was delivered to native coronary arteries after successful balloon angioplasty in 30 patients. Four patients required stent deployment in the first week. Quantitative coronary angiography and IVUS were performed during the initial procedure and at 6-month follow-up. Binary angiographic restenosis was present in 3 of 30 patients, with target lesion and vessel revascularization performed in 3 and 5 patients, respectively. Angiographic late loss was -0.02+/-0.60 mm, with a -0.09+/-0.46 loss index. IVUS demonstrated no significant reduction in lumen area (from 5.69+/-1.72 mm2 after treatment to 6. 04+/-2.63 mm2 at follow-up), with no significant change in external elastic membrane area (13.71+/-4.54 to 14.22+/-4.71 mm2) over the 6-month follow-up. Wall area was 8.01+/-3.85 mm2 after radiation therapy and 8.19+/-3.44 mm2 at follow-up (P=NS). No significant differences were noted between the different dose groups.

CONCLUSIONS

beta-Radiation therapy resulted in a low restenosis rate with negligible late loss by angiography. By IVUS, beta-radiation was shown to inhibit neointima formation, with no reduction of total vessel area at 6-month follow-up.

Efficacy of beta radiation in prevention of post-angioplasty restenosis. An interim report from the beta energy restenosis trial

Restenosis remains a major limitation of coronary angioplasty in spite of major advances in techniques and technology. Recent studies have demonstrated that ionizing radiation may limit the degree of this problem. Gamma radiation has been shown to be effective in reducing in stent restenosis in humans, and beta radiation following encouraging results in animals has been shown to be feasible in humans. The objective of this study was to assess the feasibility of a 5 F non-centered catheter to deliver beta radiation emitting seeds to the lesion site post angioplasty and its effect on restenosis. Following successful angioplasty, patients were randomized to treatment with 12, 14 or 16 Gy at the angioplasty site. This was delivered with a 5 F non-centered catheter. Twelve beta radiation emitting seeds (90Sr/Y) were delivered to an area 3 cm in length to cover the angioplasty site. Angiographic follow-up was performed at 6 months. Baseline and follow-up angiograms were performed by blinded investigators at a core laboratory. This interim report comprises the first 35 patients to complete 6-month angiographic follow-up. There were no major radiation incidents. Four patients had evidence of angiographic restenosis. The MLD (mm) and percent stenosis were 0.77 +/- 0.27/72.5 +/- 8.6 pre angioplasty, 2.08 +/- 0.4/25.7 +/- 9.8 post angioplasty and radiation and 2.05 +/- 0.59/25.7 +/- 19.8 at follow-up respectively.

CONCLUSION

Beta radiation can be feasibly and safely delivered post coronary angioplasty with a very encouraging reduction of restenosis.

Panic disorder in coronary artery disease patients with noncardiac chest pain

In this study we address the following questions: (1) What percentage of coronary artery disease (CAD) patients that present with chest pain, but whose symptoms cannot be fully explained by their cardiac status, suffer from panic disorder (PD)? (2) How do patients with both CAD and PD compare to patients without CAD and to patients without either PD or CAD in terms of psychological distress? Four hundred forty-one consecutive walk-in emergency department patients with chest pain underwent a structured psychiatric interview (ADIS-R) and completed psychological scales. Fifty-seven percent (250 of 441) of these patients were diagnosed as having noncardiac chest pain and constituted this study's sample. A total of 30% (74 of 250) of noncardiac chest pain patients had a documented history of CAD. Thirty-four percent (25 of 74) of CAD patients met criteria for PD. Patients with both PD and CAD displayed significantly more psychological distress than CAD patients without PD and patients with neither CAD nor PD. However, they did not differ from non-CAD patients with PD. PD is highly prevalent in patients with CAD that are discharged with noncardiac diagnoses. The psychological distress in these patients appears to be related to the panic syndrome and not to the presence of the cardiac condition.

Panic disorder in emergency department chest pain patients: prevalence, comorbidity, suicidal ideation, and physician recognition

PURPOSE

To establish the prevalence of panic disorder in emergency department (ED) chest pain patients; compare psychological distress and recent suicidal ideation in panic and non-panic disorder patients; assess psychiatric and cardiac comorbidity; and examine physician recognition of this disorder.

DESIGN

Cross-sectional survey (for psychiatric data). Prospective evaluation of patient discharge diagnoses and physician recognition of panic disorder.

SETTING

The ambulatory ED of a major teaching hospital specializing in cardiac care located in Montreal, Canada.

SUBJECTS

Four hundred and forty-one consenting, consecutive patients consulting the ED with a chief complaint of chest pain.

PRIMARY OUTCOME MEASURE

Psychiatric diagnoses (AXIS I). Psychological and pain test scores, discharge diagnoses, and cardiac history.

RESULTS

Approximately 25% (108/441) of chest pain patients met DSM-III-R criteria for panic disorder. Panic disorder patients displayed significantly higher panic-agoraphobia, anxiety, depression, and pain scores than non-panic disorder patients (P < 0.01). Twenty-five percent of panic disorder patients had thoughts of killing themselves in the week preceding their ED visit compared with 5% of the patients without this disorder (P = 0.0001) even when controlling for co-existing major depression. Fifty-seven percent (62/108) panic disorder patients also met criteria for one or more current AXIS I disorder. Although 44% (47/108) of the panic disorder patients had a prior documented history of coronary artery disease (CAD), 80% had atypical or nonanginal chest pain and 75% were discharged with a "noncardiac pain" diagnosis. Ninety-eight percent of the panic patients were not recognized by attending ED cardiologists.

CONCLUSIONS

Panic disorder is a significantly distressful condition highly prevalent in ED chest pain patients that is rarely recognized by physicians. Nonrecognition may lead to mismanagement of a significant group of distressed patients with or without coronary artery disease.

Is cardiac migraine a clinical entity?

Chest pain because of a disorder of the coronary circulation is assumed to be ischemic in nature. Irrespective of the underlying pathophysiological mechanism, it is accepted that all routes lead to myocardial ischemia in the pathway to anginal pain. The authors describe a patient with a history of vasoactive disorders including migraine, asthma, documented variant angina with prolonged episodes of chest pain, and scintigraphic evidence of inferior and posterior wall ischemia during exercise and ergonovine testing in the absence of significant underlying stenoses. Remarkably, severe retrosternal chest pain, ST segment depression in multiple leads, and relative increased uptake in the inferior and posterior walls on Tc-99m sestamibi tomographic images developed during pharmacologic coronary vasodilatation with dipyridamole, leading the authors to speculate as to the possible existence of a nonischemic chest pain syndrome caused by coronary vasodilatation either in association with variant angina or as a separate entity.

Time course of technetium-99m sestamibi myocardial distribution in dogs with a permanent or transient coronary occlusion

The influence of duration of coronary occlusion and reperfusion on technetium-99m hexakis-2-methoxyisobutylisonitrile (99mTc-sestamibi) myocardial redistribution between necrotic, salvaged and non-ischaemic myocardium was investigated in dogs submitted either to a 90-min or a 24-h permanent left descending coronary artery occlusion (groups 1 and 2) or to a 90-min occlusion followed by 30 min, 6 h or 22.5 h of reperfusion (groups 3, 4 and 5). In all groups, 99mTc-sestamibi and radiolabelled microspheres were injected at 45 min of occlusion. After delimiting the area at risk and the infarct by Evans blue perfusion and triphenyltetrazolium chloride staining, radioactivity of heart slices from normal, viable-ischaemic and necrotic myocardium was measured in a gamma counter. A significant (P < 0.001) linear relationship between 99mTc-sestamibi distribution and myocardial blood flow was observed in the area at risk of groups 1 (r = 0.92), 2 (r = 0.84), 3 (r = 0.90), 4 (r = 0.93) and 5 (r = 0.58). In all groups, the mean percentage of 99mTc-sestamibi uptake in the ischaemic over normal zone overestimated significantly (P < 0.05) the mean percentage of the ratio in myocardial blood flow measured with microspheres (group 1: 13.3 +/- 1.4 vs. 7.7 +/- 1.2; group 2: 15.9 +/- 2.0 vs 5.6 +/- 1.2; group 3: 14.9 +/- 1.6 vs 6.2 +/- 1.0; group 4: 20.9 +/- 1.7 vs 10.9 +/- 1.8; group 5: 51.0 +/- 2.7 vs 14.0 +/- 2.0).(ABSTRACT TRUNCATED AT 250 WORDS)

Normal qualitative and quantitative Tc-99m sestamibi myocardial SPECT: spectrum of intramyocardial distribution during exercise and at rest

Exercise myocardial perfusion imaging with Tc-99m sestaMIBI is routinely used to detect underlying coronary stenoses. Ischemia is diagnosed in regions that display decreased tracer uptake during exercise as compared to rest. Tc-99m sestaMIBI SPECT images of 42 healthy volunteers were assessed both qualitatively (tomographic slices) and quantitatively (sectored polar map) for potential sources of misinterpretation. On the myocardial tomographic slices, the most common culprit artifacts were diaphragmatic attenuation and bowel interposition, which caused fixed or reversible "perfusion defects" in the inferior and posterior regions (in 19/35 abnormal segments), and artifacts related to the presence and shift of hot spots (observed in 11/28 men; in women, they were more difficult to demonstrate because of the overriding effect of breast attenuation). Hot spots shifts between exercise and rest usually resulted in pseudo-reversible defects in the anterolateral and lateral walls. The quantified polar map display of the myocardium showed a physiologic decrease in sestaMIBI activity in the basal anterolateral and basal posterolateral areas in men during exercise. There are many normal variants that may mimic coronary artery disease on tomographic sestaMIBI images. Before reporting an area of decreased activity as either a fixed or reversible perfusion defect, the interpreter should ensure that it does not represent an artifact or a normal variation in the intramyocardial distribution of sestaMIBI during exercise.

Effect of reperfusion on 111In-antimyosin monoclonal antibody uptake by salvaged and necrotic myocardium in the dog

OBJECTIVE

The aim was to investigate the ability of 111In-antimyosin monoclonal antibody (111In-AMA) to differentiate between salvaged and necrotic myocardium following reperfusion.

METHODS

Dogs submitted to a 24 h left anterior descending coronary artery occlusion (group 1, n = 10) or to a 90 min occlusion followed by a 22.5 h reperfusion (group 2, n = 11, group 3, n = 5) were given radiolabelled microspheres and 111In-AMA after 75 min of ischaemia (groups 1 and 2), or after 19.5 h of reperfusion (group 3). After delimiting the area at risk and the infarct by dye perfusion and triphenyltetrazolium chloride, the heart slices were imaged by scintigraphy and dissected into necrotic, viable ischaemic, and normal myocardium. Myocardial blood flow was estimated by microspheres and 111In-AMA uptake was expressed as the ratio of the corresponding non-ischaemic tissue samples taken from opposite ventricular wall.

RESULTS

111In-AMA ratios in necrotic and salvaged myocardium were respectively 5.4(SEM 1.9) and 3.2(0.5) times the normal value, giving a 1.7 to 1 factor between the two areas in dogs with permanent occlusion (group 1). Similar results were obtained in group 3 with ratios of 6.1(1.1) and 3.0(0.3) times normal values. In contrast, ratios of 43.6(5.6) and 5.6(0.9) (p < 0.05) in necrotic and salvaged myocardium, respectively, were found in reperfused group 2, giving a 7.8 to 1 factor between the two tissue areas of the risk territory. Clear delineation between salvaged and necrotic tissue territories could be made on scintigrams only in group 2, which otherwise presented smaller infarcts: 35.1(7.9)% of the risk area v 58.0(8.7)% in non-reperfused animals (p < 0.05). 111In-AMA uptake by necrotic myocardium did not correlate with collateral (group 1) or reperfusion blood flows (group 3), indicating that the greater uptake in reperfused myocardium is flow independent.

CONCLUSIONS

111In-AMA does not clearly identify necrotic from viable ischaemic myocardium within 24 h of injection in a coronary artery occlusion model. Thus it may not be a sensitive enough method to evaluate infarct size progression. However, reperfusion greatly increased 111In-AMA uptake by the infarct in a flow independent manner, this may prove to be useful for clinical assessment of infarct size and reperfusion injury.

Lack of professional latitude and role problems as correlates of propensity to quit amongst nursing staff

Which job stressors are the best predictors of propensity to quit among the nursing staff in emergency wards and intensive care units are explored in this paper. Employees of 30 Quebec hospitals (i.e. 60 wards in total) participated in the study (n = 1237). Stepwise multiple regression revealed that lack of professional latitude and role problems are the best predictors of the intention to quit the organization among all nursing staff. These two job stressors are briefly addressed in the context of intervention and possible remedies aiming at improving quality of life, mental health and decreasing the rate of turnover. It is argued that such intervention would benefit the nurses, the quality of patient care, as well as the respective hospitals.

Effect of coronary reperfusion on technetium-99m methoxyisobutylisonitrile uptake by viable and necrotic myocardium in the dog

Technetium-99m hexakis-2-methoxyisobutyl isonitrile (99mTc-MIBI) distribution is flow-dependent, permitting the imaging of coronary perfusion defects. However, the behaviour of this tracer in viable and necrotic tissues within the ischaemic area at risk is still being debated. In a clinically relevant canine model, dogs were submitted either to a 24-h permanent occlusion (group 1) of the left descending coronary artery (LAD) or to a 90-min LAD occlusion followed by 22.5 h reperfusion (group 2). 99mTc-MIBI and radiolabelled microspheres were injected 3 h before sacrifice. After delimiting the area at risk and the infarct by Evans blue perfusion and triphenyltetrazolium chloride staining, heart slices were imaged by scintigraphy and tissue radioactivity measured in a gamma-counter. In the necrotic area of both groups, the 99mTc-MIBI distribution was proportional to the myocardial blood flow, approximating a 1:1 ratio (identity line slope 1, intercept 0) with highly significant correlation coefficients (group 1 r = 0.87, group 2 r = 0.86), whereas in the viable-ischaemic area of both groups, the data points are widespread above and below the identity line, indicating both over- and underestimations of blood flow in these tissue areas. These results were more pronounced following reperfusion as compared with permanent occlusion. Multiple linear regression analysis confirms differences (P less than 0.001) in 99mTc-MIBI distributions between the viable-ischaemic and the necrotic zones. Delineation of the ischaemic area at risk was possible only with permanent occlusion. A hypoperfused area was observed after reperfusion but differs from the anatomical infarcted area.(ABSTRACT TRUNCATED AT 250 WORDS)

Migration and imaging of 111Indium-labelled lymphocytes in cardiac allograft rejection

BACKGROUND

The diagnosis of cardiac allograft rejection is based on routine endomyocardial biopsy. To study an alternative method the authors evaluated the migration and scintigraphic imaging of 111Indium-labelled lymphocytes in a model of acute heart allograft rejection.

METHODS AND RESULTS

Cervical heterotopic heart transplantation was performed in 10 dogs. Blood samples were harvested at 24 and 48 h after surgery for labelling of 36 +/- 6 x 10(6) lymphocytes with 6.62 +/- 0.56 MBq of 111Indium. Daily blood samples and heart biopsies were obtained for nuclear counting on the next three days; animals were sacrificed and both donor and native hearts were studied. Between 20 and 31% of autologous labelled lymphocytes remained in circulation until 72 h after injection. Maximal plasma 111Indium activity was 315 +/- 90 compared with 5513 +/- 1483 cpm/mL in whole blood (P less than 0.05). An average of 10,176 +/- 3444 labelled lymphocytes per gram of tissue were present in allograft biopsies while histological evaluation showed mild to moderate acute rejection. The ratio of tissue biopsy to blood 111Indium counts varied from 0.7 +/- 0.2, 6 h after autologous injection to 8.5 +/- 3.8 48 h later (P less than 0.05). At autopsy, 298 +/- 66 labelled cells per gram of tissue were present in native hearts compared with 2686 +/- 711 in allografts (P less than 0.05). Scintigraphic imaging using holospectral acquisition was performed; six lateral projections showed an indium activity ratio (transplanted heart to background tissue) of 2.8, 24 to 72 h after autologous injection of labelled cells.

CONCLUSIONS

Labelling of a small number of lymphocytes with 111Indium gave a stable population of circulatory lymphocytes for studying migration of labelled cells into allografts and a noninvasive scintigraphic approach to diagnose cardiac allograft rejection.

Operator stress and monitoring practices

This study attempted to identify the major sources of work-related stress among telephone operators, with special emphasis on computer monitoring and telephone surveillance. A cross-sectional random sample of over 700 telephone operators participated in a questionnaire survey (response rate = 88%). The survey included items designed to measure perceived stress, management practices, specific job stressors and monitoring preferences. Call-time pressure items were most strongly linked to job stress by operators, with 70% reporting that difficulty in serving a customer well and still keeping call-time down contributed to their feelings of stress to a large or very large extent. About 55% of operators reported that telephone monitoring contributed to their feelings of job stress. If given the opportunity, 44% of operators stated they would prefer not to be monitored by telephone at all, while 23% stated they would prefer some monitoring; 33% had no preference. The setting of inappropriate individual-call-time objectives, which may be consistently unachievable for some operators and which create conflict between management demands for quantity and quality and also between workers values concerning quality and productivity demands, appears to be the most stress-inducing aspect of the job. In terms of telephone surveillance, the issues of timeliness and specificity of feedback appear to be less important than call-time pressure.

Technetium-99m sestamibi tomography in patients with spontaneous chest pain: correlations with clinical, electrocardiographic and angiographic findings

The sensitivity and specificity of technetium-99m hexakis-2-methoxy-2-isobutyl-isonitrile (sestamibi) single-photon emission computed tomographic (SPECT) imaging for the diagnosis of coronary artery disease were studied in 45 patients admitted to the hospital for clinical suspicion of unstable angina. Only patients without prior myocardial infarction were included and all patients had technetium-99m sestamibi injection and a 12-lead electrocardiogram (ECG) during and less than or equal to 4 h after an episode of chest pain. Coronary angiography performed in all patients during hospitalization showed significant coronary artery disease (greater than or equal to 50% luminal diameter reduction) in 26 of the 45 patients. The SPECT studies obtained after injection of technetium-99m sestamibi during an episode of spontaneous chest pain showed a sensitivity of 96% for the detection of coronary artery disease; the 12-lead ECG obtained at the time of the injection had a sensitivity of 35%. With the patient in the pain-free state, respective sensitivity values were 65% and 38%. Specificity for the radionuclide study was 79% during pain and 84% in the pain-free state; for the ECG, it was 74% both during and between episodes of pain. The site of the perfusion defect corresponded to the most severe coronary artery lesion in 88% of patients. The severity of the perfusion defect correlated with the extent of coronary artery disease: the defect score was 5.3 +/- 3.3 with one-vessel disease, 4.9 +/- 2.8 with two-vessel disease and 10.5 +/- 5.0 with three-vessel disease (p less than 0.01).(ABSTRACT TRUNCATED AT 250 WORDS)

The use of a 51Cr technique to detect gastrointestinal microbleeding associated with nonsteroidal antiinflammatory drugs

Of techniques used to evaluate gastrointestinal (GI) bleeding, use of radiochromium (51Cr)-tagged erythrocytes is the most quantitative and scientifically acceptable method. The value of this technique as well as systematic errors possible with its use are discussed. The medical literature concerning 51Cr evaluation of GI microbleeding with naproxen therapy is critically reviewed. We suggest that future studies using this technique be parallel, randomized, double-blind, and include a 1-week placebo baseline phase for all subjects. Treatment with nonsteroidal antiinflammatory drugs (NSAIDs) should last 3 to 4 weeks. A parallel group of subjects should receive placebo throughout the study. For valid statistical analyses, randomization must achieve baseline comparability of weight, height, age, and sex in the treatment groups. Data transformations may be necessary to satisfy the assumptions of the statistical model. Following these guidelines will enable investigators to better evaluate GI microbleeding during treatment with naproxen or other NSAIDs, and, hopefully, to establish the safety profiles of these drugs.

Intrinsic job stress and diastolic blood pressure among female hospital workers

The present study of 375 female hospital workers assesses the impact of two specific dimensions of vocational stress on standing diastolic blood pressure. Both intrinsic (pertaining to job content) and extrinsic (associated with job context) stressors were examined in this study. Diastolic blood pressure was found to be significantly related to scores on an intrinsic stress measure, but not with the extrinsic one, even after the contribution of obesity and age levels were controlled. However, the effect of intrinsic stress was only found to be significant among women younger than 35. We believe this to be preliminary evidence that perceived dimensions of chronic intrinsic role stressors can be significant psychosocial correlates of diastolic blood pressure.

Effects of sino-atrial ischaemia on the heart rate response to phasic burst stimulation of the right cervical vagus in the dog

The effects of occluding sinus node arteries on the pacemaker responses to graded phasic burst stimulation of the right cervical vagus were studied in anaesthetised dogs. In six dogs (Group I), phase response curves (vagally affected atrial cycle plotted against the phase of the stimulus in the cycle) to 1, 3 and 5 pulse burst stimulations were determined at control and hourly for 3 h after the occlusion. In four dogs, the occlusion produced a slowing of the heart rate, a shift of pacemaker outside sinus node region and a displacement of the phase response curves upward and to the right. Identical stimulation bursts resulted in significantly longer atrial cycles than at control, and bursts introduced with a longer phase remained effective and resulted in significantly longer atrial cycles than the maximum one reached at control. However, when the vagal responses were corrected for occlusion-induced changes in spontaneous PP intervals, the occlusion was found not to significantly affect the vagal responses except to increase their variability. Time-related differences in the effects of the occlusion were not statistically significant. In six control dogs (Group II) submitted to the same protocol, occlusion excepted, the vagal response curves changed very little over the 3 h experiments, thus confirming the stability of the experimental preparation used and of the vagal responses obtained in the absence of ischaemia.(ABSTRACT TRUNCATED AT 250 WORDS)

Gastrointestinal microbleeding after aspirin and naproxen

Gastrointestinal bleeding is the most serious side effect encountered with the anti-inflammatory antirheumatic drugs. Using the 51Cr labeling technique, the comparative quantity of blood loss with aspirin or naproxen has been previously done on normal volunteers. With the present study, 12 rheumatoid arthritic patients were controlled in a double-blind crossover study with the same radioactive technique. There is a difference in favor of naproxen. The difference between the baseline period and naproxen administration was not statistically significant.

The influence of vesical distension on the urethral resistance to flow: a possible role for prostaglandins?

The possible role of prostaglandins in the mediation and/or modulation of the urethral response to vesical distension was investigated in female dogs. Three criteria for the possible involvement of these mediators have been investigated. Indomethacin could block the reduction of urethral resistance observed during vesical distension. Intra-arterial infusion of exogenous prostaglandin E2 resulted in a dose-dependent reduction in the urethral resistance to flow. Moreover, a significant release of prostaglandin E2 in the venous blood during the course of vesical distension could be demonstrated. The functional significance, mechanisms of release and mode of action of these highly active lipids are discussed.

Gastrointestinal microbleeding in normal subjects receiving acetylsalicylic acid, placebo, and R-803, a new antiinflammatory agent, in a design balanced for residual effects

This study was undertaken to compare the relative gastrointestinal toxicity of equipotent doses of acetylsalicylic acid (ASA), 900 MG q.i.d., and a new anti-inflammatory agent, R-803, 300 mg q.i.d., against placebo. Gastrointestinal micro-bleeding was quantitated with the 61Cr-labeled erythrocyte assay. The experimental design was balanced for residual effects in the first week following any treatment. An interesting relationship between stool weight and blood loss was found to influence the microbleeding independently of the treatments themselves. All observed blood loss values were corrected by regression to a reference stool weight of 100 Gm. Final analysis of corrected values was done on arithmetic and logarithmic scales. On both scales, R-803 induced much less blood loss than ASA. A difference of 1.3 ml/day between R-803 and placebo was not statistically significant on the arithmetic scale. On the log scale, a statistically significant difference was found; but since it corresponds to 0.4 ml/day, it was not considered to be clinically significant at this dosage.

Gastro-intestinal microbleeding under acetylsalicylic acid, ketoprofen and placebo

A quantitative comparison of gastro-intestinal microbleeding induced by acetylsalicylic acid (ASA), 3.6 g daily, ketoprofen (KETO), 200 mg daily and placebo (P) was undertaken in 12 normal volunteers using a double-blind factorial design with repeated measures. We conclude that KETO induces less gastro-intestinal bleeding than ASA but more than placebo and that there is a significant residual bleeding under placebo following ASA.

Effect of naproxen on gastrointestinal microbleeding following acetylsalicylate medication

This study was undertaken to determine if substitution of naproxen for ASA does influence salicylate-induced gastrointestinal bleeding. Twelve normal volunteers were selected and given increasing doses of salicylate until guaiac tests were consistently positive. Autologous labeling of their red blood cells with 51-Cr was used to quantitate the microbleeding. After two weeks on ASA, six subjects were double blindly switched to naproxen and six to placebo for another two weeks of observation. Two-way analysis of variance on the raw data shows a significant treatment effect associated with a significant interaction in both groups. Final analysis on a logarithmic scale permits orthogonal contrasts to be accurately made without any significant remaining interaction. It is concluded that substitution of naproxen for ASA at a dose of 500 mg daily is accompanied by a rapid reduction of microbleeding to "normal" levels.