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PubMed1989

Tissue plasminogen activator: Toronto (TPAT) placebo-controlled randomized trial in acute myocardial infarction.

The efficacy and safety of recombinant tissue plasminogen activator (rt-PA) administered on a dosing per weight basis was evaluated in a randomized, placebo-controlled, double-blind trial in 115 patients with acute myocardial infarction. The principal outcomes were global and regional left ventricular function in the distribution of the qualifying myocardial infarction, determined 9 days after the onset of symptoms. Global and regional ejection fraction values were significantly better for patients treated with rt-PA than for placebo-treated patients (the differences were 5.8 +/- 2.7% units [p = 0.017] and 7.1 +/- 3.1% units [p = 0.012], respectively). This benefit was also evident from visual assessment of left ventricular segmental wall motion. After adjustment for differences in important prognostic variables at baseline, the estimates of treatment effect were 4.0 +/- 2.4% units (p = 0.048) for global and 4.3 +/- 2.6% units (p = 0.047) for regional ejection fraction. Early patency of the infarct-related vessel was demonstrable in 7 (29%) of 24 placebo-treated patients and 18 (78%) of 23 rt-PA-treated patients, whereas 15 (56%) of 27 patients in the placebo group and 23 (72%) of 32 in the rt-PA group had a patent infarct-related vessel at hospital day 9. There was no significant difference in irreversible or reversible defect size as assessed by thallium scintigraphy on day 7.(ABSTRACT TRUNCATED AT 250 WORDS)

Double-Blind Method↗

PubMed1985

Behavioral correlates of computed tomographic (CT) scan changes in older psychiatric patients.

Fifty psychiatric inpatients aged 50 and over, with no hard neurologic findings, and with a variety of DSM-III diagnoses (adjustment disorder, affective illness, and dementia), were rated for behavioral and psychiatric symptoms using the Geriatric Rating Scale and the Nurse's Assessment of Global Symptomatology-Elderly. These clinical ratings were correlated with computed tomographic (CT) scan assessments of various superficial cerebral regions as well as with linear measures of ventricular size. Behavioral deficits in activities of daily living (ADL) plus an interactional variable, inability to respond to requests, were correlated with superior temporal and inferior parietal CT abnormalities, particularly on the left side. Suspiciousness and peculiar thinking, mood lability and irritability, as well as impaired memory with confusion, perplexity, and disorientation were also associated with atrophy in these same regions. Prefrontal area defects correlated with mood lability and deficits in visual-interactional responsiveness. Statistically controlling for effects of age and alcohol abuse did not alter the basic nature of these results. Regional cerebral specialization in relation to these results are discussed using concepts developed by Luria.

Activities of Daily Living↗

PubMed1983

Effects of afterload reduction on global left ventricular and regional myocardial functions in the isolated canine heart with stenosis of a coronary arterial branch.

We examined the effects of graded reduction of afterload on the global left ventricular and regional myocardial functions as well as coronary hemodynamics in hearts with regional ischemia. We used isolated, paced canine hearts that were loaded with a hydraulic system that simulated the aortic input impedance of the dog's arterial tree. The loading conditions could be quantitatively and sequentially changed by the reduction of the systemic vascular resistance of the hydraulic system, while the preload was kept constant using a variable-height reservoir connected to the left atrium. The heart was perfused with arterial blood from a support dog. Mean coronary perfusion pressure was maintained equal to mean aortic pressure (AoP) by a servo-controlled pump. Then, the left circumflex branch was constricted to an approximate 50% flow reduction of the preischemic control condition. The myocardial lengths at ischemic and nonischemic regions were measured with two pairs of ultrasonic crystals. In the hearts without ischemia, cardiac output continued to increase, from 535 +/- 14 to 1181 +/- 74 ml/min (p less than 0.01), as mean AoP decreased fom 111 +/- 4 to 52 +/- 3 mm Hg (p less than 0.01), although mean coronary blood flow decreased by approximately 50%. During regional ischemia, at control pressures, performance of the ischemic region diminished from 0.94 +/- 0.15 to 0.77 +/- 0.15 mm (p less than 0.05). With a small decrease in afterload, from 98 +/- 6 to 86 +/- 3 mm Hg, performance improved slightly as in the normal region. With a larger reduction in afterload, from 86 +/- 3 to 55 +/- 6 mm Hg, performance of the ischemic region decreased from 0.77 +/- 0.15 to 0.61 +/- 0.15 mm (p less than 0.05) while cardiac output increased. Thus, there appears to be a bimodal change in performance: a baseline performance, perfusion pressure-mediated decrease and a second, afterload-modulated change.

Animals↗

PubMed1995

Fatigue behavior of the equine third metacarpus: mechanical property analysis.

This is the first in a series of experiments to study the fatigue properties of equine cannon (third metacarpal) bone specimens from Thoroughbred racehorses. Monotonic and fatigue tests to failure were performed in four-point bending on diaphyseal specimens in a 37 degrees C saline bath to answer three initial questions. (a) Will a linear variable differential transducer yield the same elastic modulus as strain gauges? (b) Will fatigue results depend on whether the periosteal or endosteal side of the beam is in tension? (c) Are there regional variations in the monotonic and fatigue properties of the cannon bone midshaft? Eighteen left-right pairs of specimens from six horses were used. One beam of each pair was fitted with strain gauges. Fatigue tests were conducted on 24 specimens under load control at 2 Hz; an initial range of 0-10,000 microstrain was used so as to produce failure in a reasonable period of time. There were no left-right differences in the fatigue or monotonic properties, and the presence of a gauge had no effect on modulus measured by a linear variable differential transducer. However, gauge-measured moduli were about 1 GPa less than transducer-measured values. Fatigue life was independent of which side of the beam was in tension, and there were significant variations in mechanical properties around the cortex. The lateral region was stiffer than the dorsal region but the latter had a longer fatigue life. The fixed cylindrical supports used in this experiment eventually produced slight wear grooves, causing artifactual stiffening at the end of the load cycle in some specimens. A second experiment using roller supports confirmed the reason for this stiffening. It also showed that fatigue life was shorter when roller supports were used but regional differences were similar.

Analysis of Variance↗

PubMed1984

Increased regional myocardial blood flows and oxygen deliveries during hypoxemia in lambs.

Newborn humans may develop myocardial dysfunction in conjunction with severe birth asphyxia. Subendocardial or papillary muscle ischemia appears to be the basis for the myocardial dysfunction, yet patent coronary arteries have been demonstrated in the nonsurvivors. The asphyxiated newborns also have experienced hypoxemia, which has been suggested as the cause of myocardial ischemia. This study was designed to determine the relationship between reduced aortic blood oxygen content and blood flow as well as oxygen delivery within different regions of the heart. Three days after surgery, we measured blood flow and oxygen delivery to the free walls and papillary muscles of the right and left ventricles, the ventricular septum, and the atria in 10 lambs, during 20-min periods in 8-10% and 5-6% environmental oxygen concentrations. In each region of myocardium, blood flow increased linearly as the aortic blood oxygen content decreased. The slopes of the regression lines were similar for each region of ventricular myocardium. Atrial myocardial blood flow also increased as a linear function of the reductions in aortic blood oxygen content, but at a slower rate than in the ventricular regions. Hypoxemia was associated with increased oxygen delivery in each region of myocardium, but the two variables were not related in a linear or quadratic fashion. The results demonstrate that isolated hypoxemia is associated with increased blood flow and oxygen delivery in the free walls and papillary muscles of the right and left ventricles, the ventricular septum, and the atria.

Animals↗

PubMed1993

Spontaneous variability of regional haemodynamics in unanaesthetized rats.

AIM: To study the spontaneous variability in regional haemodynamics. METHODS: Twenty normotensive Wistar-Kyoto rats were chronically instrumented with an arterial catheter and with pulsed Doppler flowmeters on the distal aorta, and the superior mesenteric and left renal arteries. After surgical recovery, the rats were monitored in unrestrained conditions. The recorded signals were analysed beat-to-beat to obtain means and coefficients of variation for mean arterial pressure, heart rate, regional blood flow velocity (consecutive 0.8-s periods) and indices of regional vascular resistance (0.8-s ratio of mean arterial pressure to mean blood flow velocity). RESULTS: Muscle and splanchnic blood flow velocities were markedly variable, with coefficients of variation of 12.8 +/- 0.8 and 12.2 +/- 1.7% (means +/- SEM), respectively, about twice as large as the coefficient of variation for mean arterial pressure (6.2 +/- 0.3%). The renal blood flow velocity was slightly less variable than the muscle and splanchnic blood flow velocities, with a coefficient of variation of 10.4 +/- 0.8%, but still markedly and significantly more variable than systemic arterial pressure. A contingency analysis of paired variations in any two given parameters (arterial blood pressure, heart rate, blood flow velocities and indices of vascular resistance) showed a concordant pattern, the only exception being a distinctly discordant trend for the covariations in muscle and splanchnic blood flow velocities. CONCLUSIONS: Regional blood flow velocity and vascular resistance have a larger degree of spontaneous variability than systemic arterial pressure. Renal blood flow velocity is also highly variable, suggesting that short-term stimuli that affect the renal blood vessels are not countered by autoregulation to any great degree. We conclude that while central factors may drive concordant regional haemodynamic variations, some opposing changes in regional blood flow velocity may cancel each other out, thereby reducing the variability in systemic blood pressure.

Animals↗

PubMed1993

Rates of protein synthesis in different regions of the normotensive and hypertrophied heart in response to acute alcohol toxicity.

The objective of study was (a) to investigate whether protein synthesis in different regions of the heart (i.e. left and right atria, left and right ventricles) expressed equal sensitivity to acute ethanol dosage, and (b) to ascertain whether concomitant cardiac abnormalities (i.e. experimental hypertrophic heart disease) exacerbated these responses. Acute ethanol dosage (75 mmol/kg body weight, i.p.) to mature male Wistar rats reduced the fractional rate of protein synthesis (ks, %/day) in all regions (atria and ventricles) of the normal and overloaded (30 days aortic constricted) hearts. The responses in ks were variable. In normal heart, the atrial tissues showed a slightly greater decrease in ks (approx. -30%) when compared to the ventricular regions (approx -20%). The most pronounced effects occurred in the hypertrophied left ventricular tissues where the depressive effects of ethanol on the rate of protein synthesis were potentiated in the presence of hypertrophy (ks reduced by approx 40%). Other regions of the overloaded heart did not show additional sensitivity to the effects of ethanol on protein synthesis in the presence of chronic hypertension. In conclusion, the deleterious effects of ethanol on the left ventricle are additive in the presence of chronic hypertrophy. These results may have important implications for other cardiac abnormalities where there is also concomitant ethanol exposure.

Alcohol Drinking↗

PubMed1989

[The ploidy variability of human cardiomyocytes].

Unlike literature on ploidy of the human myocytes, DNA content and the number of nuclei have been revealed in the same cells. Besides, the cell ploidy were studied separately in the external, central and inner regions in the left ventricule. Considerable binucleation was revealed in normal and hypertrophic ventricles where 4c X2 was the modal cell class and there were 2c X 2, 8c X 2 and single 16c X 2 cells. Two alternative assumptions have been put forward concerning the genome differences: 1) myocytes enter in mitotic cycle under pathologic conditions or 2) the difference causes in genuine variability of the ploidy classes in normal hearts.

Adolescent↗

PubMed1981

Noninvasive detection of left ventricular dysfunction with a portable electrocardiographic gated scintillation probe device.

A comparison of left ventricular function data derived from a low cost, portable electrocardiographic gated scintillation probe (nuclear stethoscope) with conventional scintiangiographic data was performed in 68 patients. Ejection fraction correlation (r = 0.86, p less than 0.005) was better in patients with uniform wall motion than in those with regional asynergy (r = 0.68 p less than 0.01). Probe variables reflecting systolic emptying rates, diastolic filling rates and timing intervals, and relative volumes analyzed in combination provided 100 percent sensitivity, specificity, and predictive value in detecting abnormal left ventricular performance. The results suggest that radionuclide angiography with an electrocardiographic gated scintillation probe is a sensitive, rapid and relatively inexpensive portable method of screening for cardiac dysfunction with a yield similar to that from the more costly gamma camera derived scintiangiogram.

Electrocardiography↗

PubMed1987

Beneficial long-term effect of intracoronary perfluorochemical on infarct size and ventricular function in a canine reperfusion model.

The administration of a drug soon after reperfusion that could enhance myocardial salvage would have important clinical application. The aim of this study was to assess the long-term effect of the perfluorochemical, Fluosol DA 20%, on infarct size, infarct morphology, ventricular ectopic activity and serial regional ventricular function in a 2 week closed chest canine model. After 90 minutes of proximal left anterior descending artery occlusion, animals randomly received either oxygenated Fluosol DA (n = 9) or saline solution (n = 9) intracoronary at 15 ml/kg body weight over 20 to 30 minutes. Hemodynamic variables were similar in the two groups except for transient elevation of left ventricular filling pressure immediately after infusion in the treated group. Infarct size was markedly reduced in the perfluorochemical-treated animals when expressed as a percent of the risk region (10.8 +/- 1.8% versus 28.9 +/- 5.5%, p less than 0.02) or as a percent of the total left ventricle (3.7 +/- 1% versus 10.8 +/- 8%, p less than 0.006). This was associated with greater improvement in radial shortening in the jeopardized zone at 2 weeks after reperfusion (15.3 +/- 2.8% versus 5.2 +/- 2.1%, p less than 0.01). Histologic examination revealed adequate healing in the treated animals with an increased number of swollen mononuclear cells in the border zones. Holter electrocardiographic recordings demonstrated a low frequency of ventricular ectopic beats in both groups. This study suggests that the perfluorochemical, Fluosol DA, may be a potentially useful agent in enhancing myocardial salvage after successful reperfusion.

Animals↗

PubMed2006

Left-right lineage analysis of the embryonic Xenopus heart reveals a novel framework linking congenital cardiac defects and laterality disease.

The significant morbidity and mortality associated with laterality disease almost always are attributed to complex congenital heart defects (CHDs), reflecting the extreme susceptibility of the developing heart to disturbances in the left-right (LR) body plan. To determine how LR positional information becomes ;translated' into anatomical asymmetry, left versus right side cardiomyocyte cell lineages were traced in normal and laterality defective embryos of the frog, Xenopus laevis. In normal embryos, myocytes in some regions of the heart were derived consistently from a unilateral lineage, whereas other regions were derived consistently from both left and right side lineages. However, in heterotaxic embryos experimentally induced by ectopic activation or attenuation of ALK4 signaling, hearts contained variable LR cell composition, not only compared with controls but also compared with hearts from other heterotaxic embryos. In most cases, LR cell lineage defects were associated with abnormal cardiac morphology and were preceded by abnormal Pitx2c expression in the lateral plate mesoderm. In situs inversus embryos there was a mirror image reversal in Pitx2c expression and LR lineage composition. Surprisingly, most of the embryos that failed to develop heterotaxy or situs inversus in response to misregulated ALK4 signaling nevertheless had altered Pitx2c expression, abnormal cardiomyocyte LR lineage composition and abnormal heart structure, demonstrating that cardiac laterality defects can occur even in instances of otherwise normal body situs. These results indicate that: (1) different regions of the heart contain distinct LR myocyte compositions; (2) LR cardiomyocyte lineages and Pitx2c expression are altered in laterality defective embryos; and (3) abnormal LR cardiac lineage composition frequently is associated with cardiac malformations. We propose that proper LR cell composition is necessary for normal morphogenesis, and that misallocated LR cell lineages may be causatively linked with CHDs that are present in heterotaxic individuals, as well as some 'isolated' CHDs that are found in individuals lacking overt features of laterality disease.

Activin Receptors↗

PubMed2003

Prognostic value of combined assessment of regional left ventricular function and myocardial perfusion by dobutamine and rest gated SPECT in patients with uncomplicated acute myocardial infarction.

UNLABELLED: Gated SPECT allows combined assessment of regional myocardial perfusion and left ventricular function. The aim of this study was to address the prognostic value of gated SPECT performed during dobutamine stress testing and during rest on patients with acute myocardial infarction treated with thrombolysis. METHODS: Eighty-eight consecutive patients with uncomplicated acute myocardial infarction who underwent predischarge (3-7 d after admission) dobutamine (5-40 microg/kg of body weight per minute in 3-min dose increments) and rest gated (99m)Tc-sestamibi SPECT were followed for a mean of 48 mo (range, 4-64 mo). RESULTS: Eighteen cardiac events (8 cardiac deaths and 10 nonfatal myocardial infarctions) occurred. Ischemia at dobutamine SPECT imaging (summed difference score or=>or= 1) was present in 60% of the patients. In patients without ischemia, there was a lower event rate (11%), compared with patients with mild ischemia (18%) and moderate-to-severe ischemia (40%) (P < 0.05). Patients with events showed also a higher summed difference score, compared with patients without events (2.3 +/- 1.6 vs. 1.3 +/- 1.6, P < 0.05). Independent predictors of events were the number of segments with preserved (99m)Tc-sestamibi uptake at rest and the number of akinetic or dyskinetic segments with preserved (99m)Tc-sestamibi uptake and preserved wall thickening (global chi(2) of the model, 13.6; P < 0.01). The assessment of the incremental prognostic value of variables added sequentially showed that the addition of the summed difference score added information to perfusion status at rest (P < 0.05). Combined assessment of regional myocardial perfusion and left ventricular function at rest further improved the model (P < 0.05). CONCLUSION: The present study indicated that predischarge (99m)Tc-sestamibi gated SPECT gives prognostic information on patients recovering from acute myocardial infarction. Patients with preserved systolic wall thickening should be regarded as a high-risk subgroup, requiring closer follow-up for appropriate treatment.

Dobutamine↗

PubMed1999

Specific and non-specific effects of transcranial magnetic stimulation on simple and go/no-go reaction time.

The effects of subthreshold transcranial magnetic stimulation (TMS) on simple and go/no-go reaction time (RT) tasks were studied in seven healthy volunteers. Subjects were asked to respond by abducting the thumb in a warning-imperative signal paradigm. TMS was randomly delivered at variable delays to the imperative signal (IS). Simple RT was significantly shortened when TMS was delivered to the left motor cortex and parietal regions simultaneously with IS. In the go/no-go paradigm, a similar trend to shorter RT was seen at a delay of 0 ms. Additionally, a significant shortening was observed at a delay of 90 ms with TMS over the contralateral motor cortex only. Movement-related potentials (MRPs) in the two paradigms showed a predominantly contralateral negativity approximately 80 ms preceding EMG onset. Our findings support the existence of two differentiated effects of TMS on RT: (1) one non-specific effect, evidenced in both the simple and go/no-go paradigms at a 0 ms delay, which can be at least partially explained by intersensory facilitation; and (2) a motor-specific effect of TMS, unveiled in the go/no-go paradigm at a 90 ms delay.

Adult↗

PubMed2006

Volume of left amygdala subregion predicted temperamental trait of harm avoidance in female young subjects. A voxel-based morphometry study.

We investigated the relationship between temperamental predisposition and brain structure by using a standard questionnaire and high-resolution T1-weighted magnetic resonance image (MRI) in normal young volunteers. Fifty-six subjects completed the Japanese version of the Temperament and Character Inventory (TCI, 125 items) and underwent an MRI acquisition of the brain. The gray matter (GM) was extracted from the whole brain image of the subjects and normalized to the standard brain template using statistical parametric mapping and the optimized voxel-based morphometry (VBM) method. When the score on the harm avoidance (HA) subscale was used as a dependent variable, the multiple regression analysis revealed that the HA score positively correlated with the volume of the part of left amygdala. The region-of-interest analysis showed that the correlation was significant in the female subjects but not in the male subjects. The correlation was significant even after the effects of age, depression score, and total GM volume were taken into account. The differential correlation between the sexes may be caused by differences in hormonal condition and the vulnerability of women to socio-psychological stress. In addition, the novelty seeking (NS) score positively correlated with the GM of the left middle frontal gyrus. The volume of the tail of the right caudate nucleus positively correlated with the reward dependence (RD) score. With regard to the NS and RD scores, no significant sex difference was observed in the correlation. These results indicate that the temperamental traits measured using the questionnaire may have a morphological basis in the human brain.

Adult↗

PubMed2005

Quantification of regional ventilation from treatment planning CT.

PURPOSE: We describe a method of quantifying regional ventilation from the radiotherapy treatment planning computed tomography (CT) images, with the goal of developing functional images for treatment planning and optimization. METHODS AND MATERIALS: A series of exhalation breath-hold (eBH-CT) and inhalation breath-hold (iBH-CT) CT images obtained using a feedback-guided breath-hold technique for radiotherapy treatment planning was selected. The eBH-CT was mapped on a voxel-by-voxel basis to the iBH-CT using a deformable image registration algorithm. By using the average CT number over a 3 mm(3) region surrounding each pair of mapped voxels, the change in fraction of air per voxel (i.e., regional ventilation) was calculated. This methodology was applied to a series of 22 patients. The calculated total ventilation was compared to the change in contoured lung volumes between the exhalation and inhalation CTs (measured tidal volume). RESULTS: A significant correlation was found between the calculated and measured tidal volumes for the left (R = 0.982) and right (R = 0.985), and for both lungs combined (R = 0.985). In the resulting images, the regional ventilation was highly variable and corresponded with the spatial distribution of differences in the CT values (Hounsfield units) between the eBH-CT and the iBH-CT images. CONCLUSIONS: A method of quantifying regional ventilation from radiotherapy treatment planning CT data sets was demonstrated. The ventilation images can be used in plan optimization to minimize injury to functioning lung.

Algorithms↗

PubMed2002

Event-related neural activity associated with habit and recollection.

The neural activity associated with conscious recollection and habit was examined using event-related brain potentials. In a training phase, participants learned A-B, A-C word associations in which the probability of specific responses was varied. Once a habit was established, participants studied and were tested on a series of short lists consisting of word pairs seen in training. The process-dissociation procedure was used to estimate the contribution of habit and recollection to memory performance. Habit estimates reflected the probability with which information was presented in training but recollection estimates did not show this effect. Recollection was associated with sustained negativity over the parieto-occipital region, which was opposite in polarity over the frontal regions. Indices of habit strength were associated with a sustained positivity over left fronto-temporal regions and a sustained negativity over right fronto-central regions. Partial-least squares analyses revealed two significant latent variables that distinguished recollection and habit, consistent with the distinction between consciously controlled and automatic influences of memory.

Adult↗

PubMed2006

Asymmetry of the height of the ethmoid roof in relationship to handedness.

The aim of this work was to study the handedness differences in the height of the right and left ethmoid roofs. Hand preference was assessed using the Edinburgh Handedness Inventory. The height of the right and left ethmoid roofs was measured with computerised tomography (CT). The incidence of persons who had a lower ethmoid roof on the right side was significantly greater among right-handers than among left-handers; the incidence of persons who had a lower ethmoid roof on the left side was significantly greater among left-handers than among right-handers; and right and left ethmoid roofs were equal in all ambidextrous subjects. The relationship between the asymmetric ethmoid roofs and handedness may result from the right or left embryonic craniofacial region being smaller in the right- or left-handed subjects. This is particularly important in the light of the high degree of variability in the ethmoid roof, and even between the right and left sides in a given individual. Preoperative awareness of a patient's unique sinus anatomy may help prevent iatrogenic injury to the surrounding vital structures during ethmoid sinus surgery (ESS).

Adolescent↗

PubMedDate not supplied

Individual variation of cortical surface area asymmetries.

Asymmetries in the size of cortical regions are regularly associated with functional lateralization. Assessment of cortical asymmetry is often confounded by measurement artifact and a lack of information about the normal variance of asymmetry in regions that are functionally symmetric. In order to measure hemispheric asymmetries in the surface area of cortical gyri, magnetic resonance (MR) images were acquired from 10 normal, right-handed males. Computer representations of the cortical surface in all 20 hemispheres were reconstructed from the images by first creating a white matter model and then 'inflating' it to approximate the cortical surface. The advantage of this approach is that it accurately models the deep sulci as well as the cortical surface. Surface area measurements of the whole hemisphere, the postcentral and the cingulate gyrus were collected from each subject. For each region an asymmetry score was computed based on the difference in the surface area of the left and right regions. Many subjects showed asymmetries in these two gyri; however, the mean asymmetry scores were never significantly asymmetric. The large variability of individual asymmetry scores indicates that cortical asymmetries may be present even in the absence of clear functional asymmetry. An understanding of the degree of asymmetry in structures that do not show clear functional lateralization is critical for interpreting data gathered from cortical regions that are functionally asymmetric.

Adult↗