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Thallium-201 right lung/heart ratio during exercise in patients with coronary artery disease: relation to thallium-201 myocardial single-photon emission tomography, rest and exercise left ventricular function and coronary angiography.

The aim of this study was to correlate lung thallium-201 uptake on exercise with 201Tl single-photon emission tomography (SPET) myocardial perfusion imaging, rest and exercise equilibrium radionuclide angiographic and coronary angiographic findings in patients with coronary artery disease (CAD) using a simple, reproducible lung/heart (L/H) ratio that would be easy to use in clinical practice. L/H ratio was defined on the anterior planar image obtained during exercise 201Tl SPET acquisition as the mean counts per pixel in an entire right lung field region of interest divided by the mean counts per pixel in the hottest myocardial wall region of interest. We studied 103 patients. Fifty-nine patients (group I) with <5% likelihood of CAD were used as a reference group. In 44 CAD patients (group II), L/H ratio was compared with 201Tl SPET, radionuclide angiographic and coronary angiographic variables. The group I L/H ratio of 0.35+/-0.05 (mean +/-1 SD) was significantly lower (P<0.001) than the group II L/H ratio of 0. 45+/-0.10. An L/H ratio >0.45 (mean + 2 SD in group I) was considered abnormal. In group II, L/H ratio showed a significant correlation with stress and rest 201Tl perfusion defect size (r = 0. 39 and r = 0.42, P<0.01, respectively), but not with extent of ischaemic myocardium. The mean L/H ratio was 0.41+/-0.10 in patients with one-vessel disease (n = 15), 0.46+/-0.08 in those with two-vessel disease (n = 17) and 0.47+/-0.12 in those with three-vessel disease (n = 12), but no significant difference was found between the three subgroups. L/H ratio showed a significant inverse relation with rest and exercise left ventricular ejection fraction (r = -0.37 and r = -0.50, P<0.05 and P<0.001, respectively). Using stepwise multiple regression analysis, exercise left ventricular ejection fraction and previous history of hypertension were the sole two variables independently predictive of the L/H ratio. In conclusion, although lung thallium uptake is usually found to correlate with extent and severity of CAD, increased L/H ratio should primarily be considered as a marker of exercise-induced left ventricular systolic and perhaps diastolic dysfunction, probably independent of the underlying cardiac disease.

Case-Control Studies↗

Variability and reproducibility of quantitative left ventricular angiography.

To evaluate the reproducibility of left ventricular angiography for the assessment of left ventricular (LV) function and regional wall motion, two ventriculographies were performed in the 30 degrees right anterior oblique (RAO) projection, at 15-minute intervals, in 19 patients undergoing coronary angiography. Heart rate, left ventricular systolic pressure, and end-diastolic pressure were measured 15 minutes after the first angiography returned to the baseline values (71.0 +/- 14.1 vs. 72.2 +/- 15.5 beats/minute, 153.6 +/- 18.0 vs. 152.8 +/- 19.9 mm Hg, 21.7 +/- 8.6 vs. 20.9 +/- 7.3 mm Hg, respectively). Global and regional LV performance was analyzed by two observers with a computer-assisted technique. Intraobserver mean variation of end-diastolic volume and ejection fraction was less than 3% of the control value. Interobserver mean variations for the same parameters were less than 4% of control values. For both observers, there was no significant variation of LV end-diastolic volume and ejection fraction from one study to the other. Under stable hemodynamic conditions, the mean observed variations were, depending on the observer, 5-6% of the control value for LV end-diastolic volume and 5% for ejection fraction. Analysis of segmental wall motion was also highly reproducible. The mean intraobserver variation (% of control value) of wall motion ranged from 4.4% to 9.2%, depending on the sectors studied. The mean interobserver variation, whatever the sector, ranged from 6.9% to 13.5%.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗

MR relaxometry of lumbar spine, hip, and calcaneus in healthy premenopausal women: relationship with dual energy X-ray absorptiometry and quantitative ultrasound.

This study evaluates if the reversible transverse relaxation rate (R2') assessed in vivo by MR of lumbar vertebrae, hip, and calcaneus is correlated with dual energy X-ray absorptiometry (DXA) and to quantitative ultrasound (QUS) of the calcaneus. Fifteen healthy premenopausal women aged 23-47 years were studied by DXA, QUS, and MR relaxometry. The GESFIDE sequence was used to separate the FID rate (R2*) into its two components, the non-reversible transverse relaxation rate (R2) and the reversible transverse relaxation rate (R2'). Long-term reproducibility was obtained by repeated measurements of hip and calcaneus in nine individuals after 300+/-89 days. R2' and R2* of the calcaneus had a relationship to broad-band ultrasound attenuation (BUA; r = 0.46, both p<0.05), but not to other US or DXA parameters of the calcaneus. Both R2' and R2* were correlated with bone mineral per area (BMA) of the hip (r>0.73, p<0.001 and r>0.66, p<0.01, respectively). R2 was correlated with BMA(L1-L4) (r = 0.52, p<0.05). R2' and R2* were not correlated with BMA(L1-L4). When the right and left sides were compared in calcaneus and hip the correlation coefficient for R2' and R2* ranged from 0.76 to 0.86 (p<0.001). The long-term reproducibility expressed in coefficient of variation (CV%) was approximately 5 % for R2' and approximately 4% for R2*. Differences in R2 between individuals were not reproducible. The results of this study indicate that R2' and R2* measurements are reproducible and might be of value when evaluating bone quality of the hip and foot.

Absorptiometry, Photon↗

Pulse-wave morphology and pulse-wave velocity in healthy human volunteers: examination conditions.

OBJECTIVE: Applanation tonometry for pulse-wave analysis (PWA) and determination of pulse-wave velocity (PWV) is a non-invasive method for assessment of the central aortic pressure waveform and indices of arterial stiffness. The objective of this study was to examine the influence of eating and smoking on PWA and PWV measurements in order to establish standard examination conditions. Furthermore, intra- and interobserver reproducibility and the effects of varying the site of measurements were observed. MATERIAL AND METHODS: Duplicate measurements of the radial pressure waveform and of the brachial and aortic PWV on the right and left side of the body were recorded in 23 healthy subjects by two trained observers. Measurements were performed in the fasting state and 3 h after a high-calorie meal, and before and 1 h after smoking a cigarette. RESULTS: Intake of a high-calorie meal as well as smoking caused significant changes in both PWA and PWV parameters and an inter-arm difference was observed. Intra- and interobserver reproducibility was good. CONCLUSIONS: Pulse-wave measurements by applanation tonometry should be undertaken in the same arm during fasting and smoking abstinence.

Adult↗

Right ventricular function at rest and during exercise in chronic obstructive pulmonary disease. Comparison of two radionuclide techniques.

Right ventricular function was assessed in 24 patients with COPD, at rest and during submaximal exercise, using both technetium-99m (99mTc) blood-pool and krypton-81m (81mKr) equilibrium ventriculography. Technetium-99m right ventricular ejection fraction (RVEF) at rest was lower than 81mKr RVEF (0.39 +/- 0.12 and 0.54 +/- 0.08, respectively; p < 0.001). During submaximal exercise, there was no increase in RVEF using either imaging technique. This observation contrasted with an increase in RVEF in a group of age-comparable normal subjects during modest submaximal exercise. An inability to obtain spatial separation of right heart structures using 99mTc imaging leads to a value for RVEF that is consistently lower than that measured using 81mKr ventriculography. Resting RVEF is well preserved at rest in most patients with COPD. In contrast to normal subjects, many show an inability to augment right ventricular function during exercise that may contribute to the reduced exercise capacity observed in these patients.

Aged↗

Gradient-enhanced volume rendering: an image processing strategy to facilitate whole small bowel imaging with MRI.

MRI of the small bowel with positive contrast from orally administered contrast agent is a promising non-invasive imaging method. The aim of our study was to introduce small bowel MRI in a display format that clinicians are accustomed to and that maximizes the amount of information visualized on a single image. Twelve healthy volunteers, median age 32 years (range 18-49 years) participated in the study. A mixture of 20 ml Gd-DOTA (Dotarem), 0.8 g/kg body weight psyllium fibre (Metamucil) and 1.2 l water were sequentially administered over a period of 4 h. Imaging was performed on a 1.5 T unit (Philips Gyroscan, Intera). Fat-saturated, 3D, gradient echo imaging was performed while the patient was in apnea (30 s). Bowel motion was reduced with 40 mg intravenously administered scopolamine (Buscopan). A 3D, gradient-enhanced, volume rendering technique was applied to the 3D data sets. Standard projections [left anterior oblique (LAO), right anterior oblique (RAO), supine and prone] resembling conventional enteroclysis were successfully generated within fewer than 10 min processing time. Reconstructions were reproducible and provided an entire overview of the small bowel. In addition thin-slab volume rendering allowed an overlap-free display of individual structures. Positive contrast from orally administered contrast agent, combined with a gradient enhanced volume rendering method, allows the reconstruction of the small bowel in a pattern resembling conventional double-contrast enteroclysis. Segmental display without overlay is possible.

Adolescent↗

Insights into recognition of the T-DNA border repeats as termination sites for T-strand synthesis by Agrobacterium tumefaciens.

The recognition of the T-DNA left border (LB) repeat is affected by its surrounding sequences. Here, the LB regions were further characterized by molecular analysis of transgenic plants, obtained after Agrobacterium tumefaciens-mediated transformation with T-DNA vectors that had been modified in this LB region. At least the 24-bp LB repeat by itself was insufficient to terminate the T-strand synthesis. Addition of the natural inner and/or outer border regions to at least the LB repeat, even when present at a distance, enhanced the correct recognition of the LB repeat, reducing the number of plants containing vector backbone sequences. In tandem occurrence of both the octopine and nopaline LB regions with their repeats terminated the T-strand synthesis most efficiently at the LB, yielding a reproducibly high number of plants containing only the T-DNA. Furthermore, T-strand synthesis did not terminate efficiently at the right border (RB) repeat, which might indicate that signals in the outer RB region inhibit the termination of T-strand synthesis at the RB repeat.

Agrobacterium tumefaciens↗

MRI evaluation of myocardial viability.

Cardiac magnetic resonance imaging (MRI) has become an accurate noninvasive imaging procedure for the study of postischaemic residual cardiac function, thanks to the evolution of MRI machines, postprocessing software and, above all, sequences. After infarction, and in chronic myocardial ischaemia, the degree of contractile dysfunction is one of the main determinants of longterm survival. The identification and quantification of viable dysfunctional myocardium and the possibility of improving its contractility after revascularisation improves patient prognosis and quality of life. In current clinical practice, myocardial viability is evaluated with stress echocardiography and nuclear methods. Thanks to its intrinsic characteristics and to the delayed-enhancement technique (DE-MRI), MRI has recently emerged as the only noninvasive modality able to provide a three-dimensional (3D) evaluation of cardiac viability with a multiparametric approach.

Humans↗

Influence of transdermal scopolamine on cardiac sympathovagal interaction after acute myocardial infarction.

In 41 survivors of acute myocardial infarction (AMI) a prospective study was performed in 2 sequential phases. In phase 1, the role of baroreflex sensitivity and heart rate variability as predictors of inducible and spontaneous sustained ventricular tachyarrhythmias was evaluated. In phase 2, the effects of transdermal scopolamine on baroreflex sensitivity, spectral and nonspectral measures of heart rate variability were investigated. At a mean follow-up of 10 +/- 3 months after AMI, 5 of 41 patients (12%) developed a late arrhythmic event. Of these, all (100%) had inducibility of sustained monomorphic ventricular tachycardia at programmed stimulation compared with 3 of 36 patients (8%) without events (p < 0.0001). At multivariate analysis, baroreflex sensitivity had the strongest relation to both inducibility of sustained monomorphic ventricular tachycardia (p < 0.0001) and occurrence of arrhythmic events (p < 0.0001). Of 41 patients, 28 (68%) consented to undergo phase 2 of the investigation. Baroreflex sensitivity significantly (p < 0.00001) increased after transdermal scopolamine as well as heart rate variability indexes. Of these, the mean of SDs of normal RR intervals for 5-minute segments (p < 0.0001) and the total power (p < 0.0001) had the most significant improvement after scopolamine. The present investigation confirms that assessment of autonomic function is an essential part of arrhythmic risk evaluation after AMI. Transdermal scopolamine, administered to survivors of a recent AMI, reverses the autonomic indexes that independently predict arrhythmic event occurrence. On the basis of these data, transdermal scopolamine could be a potential useful tool in the prophylaxis of life-threatening ventricular arrhythmias after AMI.

Administration, Cutaneous↗

Hemispheric asymmetry of processing temporal aspects of repetitive movement in two patients with infarction involving the corpus callosum.

Two right-handed patients with infarction involving the forebrain commissural fibres produced irregular but rapid repetitive movements with their left hands while producing normal movements with their right hands as well as having normal oral expression. The abnormality was more conspicuous when producing slow tapping patterns. When required to reproduce rapid tapping patterns of around 5 beats/sec, one of the patients produced a comparatively regular tapping pattern. Thus, we believe that both hemispheres are equipped with the faculty to produce rapid repetitive patterns and that only the left hemisphere is responsible for the temporal processes involved in producing required repetitive patterns.

Aged↗

Benzo[a]pyrene cytotoxicity in right whale (Eubalaena glacialis) skin, testis and lung cell lines.

The North Atlantic right whale (NARW) is one of the most endangered great whales. The NARW population consists of only about 300 individuals and is reproducing at an insufficient rate. There is growing concern about the potential effects of environmental contaminants on the reproductive and overall health of NARW. High contaminant burdens can accumulate in tissues of great whales but toxicological studies of their effects are limited due to legal, logistical and ethical restrictions and specific in vitro models are critically needed. Cell lines from NARW skin and internal organs were previously created in our laboratory. In this study, skin, testis and lung primary fibroblast cell lines were exposed to benzo[a]pyrene (BP) as part of a multi-chemical toxicity testing project in NARW. Cells were exposed for 24-72 h to 10 nM-10 microM BP dissolved in dimethylsulfoxide. Cytotoxicity was measured with a clonogenic assay using standard methods. Some cytotoxicity was observed after 24 h, the highest concentration (10 microM BP) resulting in 77, 74 and 51 percent relative survival in testis, skin and lung cells, respectively, and indicating a higher cytotoxicity in the lung (p < 0.05). After 48 and 72-h exposure, 10 microM BP resulted in 24 and 3, 74 and 27, and 42 and 23 percent relative survival in testis, skin and lung cells, respectively. Cytotoxicity significantly increased with exposure time in all three tissues (p < 0.05 for skin and p < 0.01 for lung and testis), suggesting metabolic activation of BP in the three organs. Fibroblast cytotoxicity observed in the testis was higher than that observed either in the skin or lung after 48 h (p < 0.01) and was close to 100% after 72 h, warranting further investigation of the potential effects of PAHs on reproductive health.

Animals↗

The plasticity of gravitational reference frame and the subjective vertical: peripheral visual information affects the oblique effect.

The experiment examined the human visual perception of orientations and the nature of reference frame in which the oblique effect (lower performance in oblique orientations than in vertical or horizontal ones) was defined. Previous research [M. Luyat, E. Gentaz, Body tilt effect on the reproduction of orientations: studies on the visual oblique effect and subjective orientations, J. Exp. Psychol. Hum. Percept. Perform. 28 (2002) 1002-1011. M. Luyat, E. Gentaz, T.R. Corte, M. Guerraz, Reference frames and haptic perception of orientation: body and head tilt effects on the oblique effect, Percept. Psychophys. 63 (2001) 541-554], using head tilt paradigm to uncouple the gravitational, egocentric and subjective reference frames, showed that the oblique effect was mapped in a subjective gravitational reference frame with the subjective vertical as a cardinal orientation. However, the subjective vertical is not only affected by the tilt of head but also by the tilt of visual context. Then, the tilt of visual oriented cues is another paradigm permitting to evidence the role of the subjective gravitational reference frame. Sixteen participants were asked to reproduce five different orientations of a luminous line: horizontal (0 degrees ), 45 degrees (oblique), 90 degrees (vertical), 135 degrees (oblique) and the subjective vertical. These orientations were reproduced with no visual contextual cues and with tilted visual contextual cues tilted 15 degrees either to the left or to the right. The results showed that the oblique effect decreased with tilted visual contexts but was not completely suppressed. These results proved that this oblique effect is defined in a multimodal reference frame which integrates not only vestibular and proprioceptive cues but also peripheral visual information.

Adult↗

Computer simulation of haemodynamic parameters changes with left ventricle assist device and mechanical ventilation.

Left Ventricular Assist Device is used for recovery in patients with heart failure and is supposed to increase total cardiac output, systemic arterial pressure and to decrease left atrial pressure. Aim of our computer simulation was to assess the influence of Left Ventricular Assist Device (LVAD) on chosen haemodynamic parameters in the presence of ventilatory support. The software package used for this simulation reproduces, in stationary conditions, the heart and the circulatory system in terms of pressure and volume relationships. Different circulatory sections (left and right heart, systemic and pulmonary arterial circulation, systemic and pulmonary venous circulation) are described by lumped parameter models. Mechanical properties of each section are modelled by RLC elements. The model chosen for the representation of the Starling's law of the heart for each ventricle is based on the variable elastance model. The LVAD model is inserted between the left atrium and the aorta. The contractility of the heart and systemic arterial resistance were adjusted to model pathological states. Our simulation showed that positive thoracic pressure generated by mechanical ventilation of the lungs dramatically changes left atrial and pulmonary arterial pressures and should be considered when assessing LVAD effectiveness. Pathological changes of systemic arterial resistance may have a considerable effect on these parameters, especially when LVAD is applied simultaneously with mechanical ventilation. Cardiac output, systemic arterial and right atrial pressures are less affected by changes of thoracic pressure in cases of heart pathology.

Animals↗

Electrophysiologic effects of mental stress in healthy subjects: a comparison with epinephrine infusion.

Mental stress has been associated with serious cardiac arrhythmias, including ventricular tachycardia and ventricular fibrillation. The purpose of this study was to assess cardiac electrophysiologic effects of mental stress and compare them with those of epinephrine infusion. Ten healthy male volunteers participated. Electrophysiologic and hemodynamic variables were measured at baseline, during mental stress produced by Stroop's color word conflict test and during epinephrine infusion at 2 rates (0.025 micromol/kg/min and 0.3 micromol/kg/min). Mental stress produced significant effects on the electrophysiologic properties of the heart with shortening of all measured electrophysiologic variables except atrial, most markedly those of the sinus and the atrioventricular nodes. The effects on the right ventricular myocardium and the His-Purkinje conduction system were less pronounced. During infusion of epinephrine, corresponding effects could only be reproduced at a much higher plasma level. Circulating epinephrine apparently plays a minor role as a mediator of mental stress effects on the heart.

Adrenergic alpha-Agonists↗

Hormone-dependent fluctuations of pressure pain threshold and tactile threshold of the temporalis and masseter muscle.

In order to better objectify reported pain and disturbed sensation, psychophysical parameters as pressure pain threshold (PPT) and tactile threshold (TT) have been introduced in pain research. The present study evaluated fluctuations of these parameters, obtained using an algometer (PPT) and von Frey hairs (TT), in relation to fluctuations in female reproductive hormones. Ten students not using oral contraceptives and eight students using oral contraceptives participated in the study. In addition, seven male students served as a control group. During two menstrual cycles, the PPT and TT of the masseter and temporalis muscles, as well as from the hand, were obtained twice per week. At the end of the study the values were evaluated in relation to the different phases of the menstrual cycle, by means of a linear mixed model. The TT appeared very reproducible within subjects and did not fluctuate over time. Scores on the left temporalis muscle appeared significantly higher than that on the right side. In all subjects the PPT tended to be higher on the left side, while in students using oral contraceptives, the PPT values of the temporalis muscle were significantly higher in the menstrual phase, and lower in the follicular phase. A significant correlation between the PPT of the temporalis muscle and the TT of the overlying skin was observed.

Adult↗

Laparoscopic right nephrectomy using a novel technique to excise an inferior vena-caval cuff in a porcine model.

BACKGROUND AND PURPOSE: Laparoscopic right nephrectomy has been performed using laparoscopic staplers to clamp and divide the renal vessels. In patients who have a tumor thrombus in the renal vein and in rightkidney donors, it is necessary to excise a cuff of the inferior vena cava (IVC) with the renal vein. We present a new technique for excising a cuff of the IVC and suturing it intracorporally using a new vascular clamp designed in our institution. MATERIALS AND METHODS: The vascular clamp was designed to be completely inserted into the peritoneal cavity through the hand-port incision. The renal vein with a cuff of the IVC was then excised, and the defect in the IVC was sutured with a vascular stitch intracorporally. This procedure was performed in the animal laboratory using a porcine model. RESULTS: A total of 20 hand-assisted right laparoscopic nephrectomies were performed. In the first five operations, the clamp dimensions and angles were modified until the ideal design was reached. In the next five operations, different suture materials and needle sizes were tried to find the best combination for the intracorporal IVC sutures. The first and second operations were not completed because of the difficulty in applying the initial version of the clamp to the IVC. In the 4th and 6th operations, bleeding occurred from the suture line: because of a missed stitch in the back wall of the IVC in one case and a needle stick to the IVC in the other case. The last 14 operations were successful without any bleeding or injuries. Suturing of the IVC was completed in 13 to 22 minutes. CONCLUSION: Right hand-assisted laparoscopic nephrectomy with excision of a cuff of the IVC using an intracorporal vascular clamp is safe and reproducible in a porcine model. In our hands, a learning curve of 10 cases was required.

Animals↗

Trier Social Stress Test: a method for use in nursing research.

BACKGROUND: Researchers face the difficulty of inducing psychosocial stress in a laboratory setting using a method that institutional review boards could consider an acceptable research protocol. METHODS: This article describes the Trier Social Stress Test, a research protocol that can be used to induce psychosocial stress and capture the integrated aspects of an individual's biologic and psychological responses. RESULTS: The test involves 15 minutes of psychosocial stress induced by a mock job interview and followed by a mental arithmetic challenge before a panel of three judges. The discomfort associated with performance requirements induces stress in socially acceptable ways that can be measured using physiologic and/or psychological parameters. CONCLUSIONS: This method allows stress to be induced and measured in a controlled, laboratory setting.

Clinical Protocols↗

A new method for measuring the diameter of the in vivo human cornea.

An in vivo method of measuring the size of the human cornea by using catoptric imagery as devised for both closed-circuit television and 35-mm camera systems. The system was validated by using precision reticules and casts of eyes. The reproducibility of the closed-circuit television system was +/- 0.11 mm. The mean horizontal corneal diameter (HCD) for a sample of the right eyes of 50 subjects was 12.89 +/- 0.60 mm. The system was also used to measure horizontal visible iris diameter (HVID). The mean HVID for the same sample was 11.64 +/- 0.49 mm. Although there was a good general correlation between HCD and HVID, the HVID was found to be a poor predictor of HCD for the individual eye.

Adult↗