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PubMed1997

Cardiac contractile function during coronary stenosis in dogs: association of adenosine in glycolytic dependence.

We tested the hypothesis that during critical coronary stenosis, endogenous adenosine alters myocardial glucose utilization to support myocardial contractile function (MCF). Anesthetized mongrel dogs were instrumented to measure hemodynamic variables, regional MCF (sonomicrometry), and substrate uptakes. Critical coronary artery stenosis was established with a screw clamp on the left circumflex coronary artery (LCX). Either 8-phenyltheophylline (3 x 10(-7) mol/min; adenosine-receptor blockade), iodoacetate (1 x 10(-5) mol/min; glycolysis blockade), or vehicle was infused into the LCX and the left anterior descending coronary artery (LAD). Critical coronary stenosis caused small decreases in arterial blood pressure and LCX blood flow, but no significant changes in MCF or other hemodynamics. There was a significant decrease in the O2 supply-to-consumption ratio in the stenotic region and an increased glucose uptake. Infusion of either 8-phenyltheophylline or iodoacetate caused a decrease in MCF in the stenotic LCX region concomitant with a decreased glucose uptake and without further changes in blood flow. This was not seen in the nonstenotic (LAD) region. These data support the hypothesis, indicating that glycolysis is vital for maintaining regional MCF during a decrease in the myocardial O2 supply-to-consumption ratio and that adenosine is important in this regard, independent of its vasoactive properties.

Adenosine↗

PubMed2002

Unusually prolonged progressing stroke: an expanding anterior cerebral artery infarction.

Progressive clinical deterioration over a period of weeks coupled with MRI evidence of infarction growth is quite uncommon. In this report, we describe a patient with an occluded left anterior cerebral artery (ACA) at the origin of the A2 segment. His symptoms attributable to a posteriorly located small infarction within the ACA territory slowly progressed during the following 8 weeks. A follow-up MRI revealed that the infarction had expanded to involve the whole region of the left ACA. Occasional patients like ours indicate that stroke is a dynamic disorder with an extremely variable clinical course and state of tissue injury.

Aged↗

PubMed1995

Hamartomatous malformation of the left ventricle associated with sudden death.

We describe unusual left ventricular cardiac lesions in a 17 year old boy who died suddenly during exertion. These consisted of two grossly evident regions of deficient myocardium, containing cavernous spaces which represented exaggerated intertrabecular regions of the left ventricular cavity. Dense fibro-elastotic tissue was deposited around these spaces along with a variable admixture of mature adipose tissue, fibrous tissue and blood vessels. The etiology of these presumably congenital developmental abnormalities is obscure. The lesions most probably represent a hamartomatous malformation, which is a poorly documented pathological entity.

Adolescent↗

PubMed2002

Variability of insulin-stimulated myocardial glucose uptake in healthy elderly subjects.

The aim of this study was to assess regional and global variability of insulin-stimulated myocardial glucose uptake in healthy elderly subjects and to evaluate potentially responsible factors. Twenty men with a mean age of 64 years, no history of cardiovascular disease, and normal blood pressure, bicycle exercise test, electrocardiogram and echocardiography were studied [ P(coronary artery disease) <5%]. Whole-body insulin sensitivity and insulin-stimulated myocardial glucose uptake were measured during hyperinsulinaemic euglycaemic glucose clamp with fluorine-18 fluorodeoxyglucose, and myocardial rest and hyperaemic blood flow during dipyridamole infusion were measured with nitrogen-13 ammonia and positron emission tomography in 16 left ventricular myocardial segments. Intra-individual and inter-individual variability of insulin-stimulated myocardial glucose uptake [relative dispersion = (standard deviation/mean)] was 13% and 29% respectively. Although inter-individual variability of glucose uptake and blood flow at rest was of the same magnitude, no correlation was found between these measures. Regional and global insulin-stimulated myocardial glucose uptake correlated linearly with whole-body insulin sensitivity ( r=0.51, P<0.05 and r=0.56, P<0.01). The strongest independent association by multivariate linear regression analysis was found between myocardial glucose uptake and hyperaemic blood flow ( r=0.63, P<0.005). We conclude that in healthy elderly subjects, insulin-stimulated myocardial glucose uptake is homogeneous throughout the left ventricle, but has moderate inter-individual variability. Inter-individual variability of insulin-stimulated myocardial glucose uptake is primarily explained by variability in coronary vascular reactivity and tissue insulin sensitivity.

Ammonia↗

PubMed2005

[The diagnostic value of non-invasive tests for determining idiopathic dilated, ischemic and hypertensive cardiomyopathies].

UNLABELLED: The objectives of this study were to detect regional myocardial perfusion defects performing 99mTc-MIBI myocardial perfusion imaging and to compare the results with echocardiography for differential diagnostics of the idiopathic dilated, ischemic and hypertensive cardiomyopathies until coronary angiography will be performed. MATERIAL AND METHODS: In total 90 patients with cardiomegaly have been evaluated: 30 patients with idiopathic dilated cardiomyopathy (group I), 30 with ischemic cardiomyopathy (group II) and 30 with hypertensive cardiomyopathy (group III). All patients underwent 2D echocardiography examination and 99mTc-MIBI myocardial perfusion imaging before coronary angiography was done. RESULTS: Informative complex findings (age, thickness of the interventricular septum, thickness of the left ventricle posterior wall, the wall motion score index in the region of the right coronary artery and the left anterior descending branch and the degree of distress of myocardial perfusion in the area of right coronary artery circulation) selected by variable logic model enabled to differentiate patients with idiopathic dilated, ischemic and hypertensive cardiomyopathies with an accuracy of 92.0%, 86.2% and 79.2%, respectively. CONCLUSION: Informative echocardiographic indices (thickness of the interventricular septum and left ventricle posterior wall, the mass of the myocardium, the wall motion score index in the region of the right coronary artery and left anterior descending branch, ejection fraction) selected by discriminative analysis enabled to differentiate patients with idiopathic dilated, ischemic and hypertensive cardiomyopathies with an accuracy of 62.1%, 75.2% and 80.0%, respectively.

Adult↗

PubMed1986

[Radionuclide ventriculographic evaluation of left ventricular systolic function in acute myocardial infarction].

Within 18 hours of acute myocardial infarction, global left ventricular (LV) function was evaluated by radionuclide ventriculography for 127 patients. Ejection fraction (EF) was calculated using a variable region of interest counts method. LV end-diastolic volume index (EDVI) was calculated from the LV outlines in the anterior and LAO projections using the area-length method. To validate the determination of EDV by the area-length method, the radionuclide EDV correlated with that derived from direct contrast angiography in 44 other patients who had both studies within two weeks, with an overall correlation coefficient of 0.84. To minimize any potential problems with the geometric ellipsoid model, the end-systolic volume index (ESVI) was calculated from EF and EDVI. Peak systolic blood pressure (PSP) was recorded with a cuff during imaging and the PSP/ESV calculated as a measure of LV contractile function. The regional wall motion of five segments in both the anterior and LAO projections were each scored on a scale, from 4 (= normal) to 0 (= dyskinesis). The wall motion index (WMI) derived from the sum of the 10 segment scores represented an overall index of wall motion (maximum = 40). In addition, the more widely used % abnormally contracting segments (%ACS) was calculated. The severity of wall motion abnormalities were associated with significant increases in heart rate and ESVI, whereas EDVI began to increase under more severe damage to the myocardium. Our data are consistent with those of Klein who found that the LV enlarges only when 20 to 25% of the surface area is rendered akinetic. There were significant decreases in EF and PSP/ESV with moderate reduction in wall motion, and the relation between EF and PSP/ESV was curvilinear. Information about ventricular volume and systolic blood pressure might be of additional value to EF for a more complete understanding of the changes in the functional state of the LV. Global LV function was compared between anterior and inferior myocardial infarcts. The size of %ACS was larger in anterior than in inferior infarction and a greater decrease in WMI in the former suggested larger infarct size in anterior infarction. As a result, ESVI was significantly larger in anterior infraction than in anterior infraction. However, an increase in EDVI was not significantly different between the two groups. EF was reduced to a greater extent in anterior than in inferior infarction. The overall data indicate that patients with anterior infarction have more severe impairment of left ventricular global function than do those with inferior infarction.

Cardiac Volume↗

PubMed1990

Augmentation of mortality risk discriminating power of left ventricular ejection fraction by measures of nonuniformity in systolic emptying on radionuclide ventriculography.

Employing equilibrium-gated radionuclide ventriculography in the left anterior oblique view, six geometric models and five mathematic coefficients of nonuniformity in regional left ventricular emptying were tested for their relative mortality risk-stratifying power and capacity to augment the risk-discriminating potency of the continuous and dichotomized global ejection fraction. Radionuclide ventriculography was performed an average of 7.6 days after acute myocardial infarction. All geometric models significantly separated 20 normal subjects from 137 patients with recent infarction (p less than 0.001). Cumulative mortality data demonstrated that significant independent univariate dichotomizing potency and augmentation of the mortality risk-discriminating power of the global ejection fraction were provided by models of regional emptying that 1) conformed to coronary artery perfusion areas, 2) encompassed total ventricular counts, 3) expressed variability in regional relative to global ejection fraction, and 4) simulated a pattern of emptying directed toward the center of geometry of the left ventricle. The combination of a four quadrant geometric model with axes drawn 45 degrees above the horizontal and a coefficient of variation calculated as square root of sigma(GEF - REF)2/4 x 100/GEF (where GEF = global ejection fraction and REF = regional ejection fraction) proved to be optimal. This coefficient averaged 12.2% in normal subjects and 32.2% in patients with recent acute myocardial infarction (p less than 0.001).(ABSTRACT TRUNCATED AT 250 WORDS)

Aged↗

PubMed1988

Effect of beta-adrenergic receptor blockade on responses to acute hypoxemia in lambs.

We studied the effects of beta-adrenergic receptor blockade on general circulatory and metabolic responses to moderate (FIO2 = 0.09) acute hypoxemia in newborn (protocol 1) and 3-wk-old (protocol 2) lambs, and on regional blood flow distribution in newborn lambs (protocol 1). Via a left thoracotomy we placed an electromagnetic flow transducer around the ascending aorta and inserted various vascular catheters. After 2 days of recovery, the lambs were studied. In protocol 1, we measured cardiovascular variables and regional blood flow distribution during control conditions, after 45 min of acute hypoxemia, and after 0.5 mg/kg of propranolol during acute hypoxemia. In protocol 2, we measured cardiovascular variables during control conditions and after 45 min of acute hypoxemia with and without propranolol pretreatment. In both groups, propranolol limited the increase in cardiac output and heart rate caused by hypoxemia, and thus decreased oxygen delivery. However, propranolol also decreased oxygen consumption so that pulmonary arterial pO2 was either higher (protocol 1) or the same (protocol 2) as during acute hypoxemia alone. Neither metabolic acidosis nor hypothermia ensued. In protocol 1, propranolol decreased renal, carcass, and most importantly, myocardial blood flows. However, myocardial O2 consumption also fell, coronary sinus pO2 increased, and blood was redistributed toward the subendocardium, suggesting that myocardial perfusion improved. Thus, beta-adrenergic receptor blockade during acute moderate hypoxemia may have a beneficial effect by reducing total body and myocardial oxygen demand in excess of the reduction in oxygen delivery.

Acute Disease↗

PubMed1998

Degree of residual stenosis of the infarct-related artery. Another variable affecting recovery of regional function after thrombolysis.

AIMS: The aim of this study was to analyse the relationship between infarct-related artery residual stenosis, assessed by quantitative coronary angiography, and left ventricular function changes during the in-hospital period in patients with acute myocardial infarction undergoing thrombolytic treatment. METHODS AND RESULTS: The study population consisted of 90 patients with acute myocardial infarction treated with thrombolysis within 6 h of the onset of symptoms. Left ventricular function was serially assessed by an echocardiographic asynergy score (before thrombolysis and pre-discharge). Left ventricular end-diastolic and end-systolic volumes were also calculated. Coronary stenosis was evaluated by computer-assisted videodensitometric analysis at pre-discharge coronary angiography. Three subgroups were identified on the basis of left ventricular function changes: 25 patients (Group A) with regional myocardial improvement (echo score from 7.5 +/- 3.5 to 4.3 +/- 3.2), 51 (Group B) with no variation in echo score (4.8 +/- 2.7) and 14 (Group C) with myocardial regional worsening (echo score from 4.4 +/- 2.1 to 8.8 +/- 2.4). Group A patients exhibited a very high incidence of infarct-related artery patency (23/25 patients, 92%) vs 71% with unchanged (Group B) and 14% (Group C) with worsening regional left ventricular function (P < 0.001). Subdivision of the study population on the basis of residual stenosis severity showed that a significant improvement in left ventricular function was present only in the subgroup with residual stenosis < 75% (echo score from 5.2 +/- 3.4 to 3.6 +/- 2.9, P < 0.001). CONCLUSION: These results support the important role exerted by complete coronary patency after thrombolysis in inducing left ventricular function recovery, and the poor functional improvement in patients with incomplete coronary patency.

Adult↗

PubMed2003

Induced oscillations and the distributed cortical sources during the Wisconsin card sorting test performance in schizophrenic patients: new clues to neural connectivity.

Prefrontal dysfunction has been associated with schizophrenia. Activation during Wisconsin card sorting test (WCST) is a common approach used in functional neuroimaging to address this failure. Equally, current knowledge states that oscillations are basic forms of cells-assembly communications during mental activity. Promising results were revealed in a previous study assessing healthy subjects, WCST and oscillations. However, those previous studies failed to meet the functional integration of the network during the WCST in schizophrenics, based on the induced oscillations and their distributed cortical sources. In this research, we utilized the brain electrical tomography (variable-resolution brain electromagnetic tomography) technique to accomplish this goal. Task specific delta, theta, alpha and beta-2 oscillations were induced and simultaneously synchronized over large extensions of cortex, encompassing prefrontal, temporal and posterior regions as in healthy subjects. Every frequency had a well-defined network involving a variable number of areas and sharing some of them. Oscillations at 11.5, 5.0 and 30 Hz seem to reflect an abnormal increase or decrease, being located at supplementary motor area (SMA), left occipitotemporal region (OT), and right frontotemporal subregions (RFT), respectively. Three cortical areas appeared to be critical, that may lead to difficulties either in coordinating/sequencing the input/output of the prefrontal networks-SMA, and retention of information in memory-RFT, both preceded or paralleled by a deficient visual information processing-OT.

Adult↗

PubMed1997

[Quantitative tissue Doppler echocardiography in comparison with M-mode measurements in healthy probands].

Quantitative tissue Doppler echocardiography is a new diagnostic approach to left ventricular systolic performance. The aim of the present study was to validate a recently developed method based on the computer software TDI-Labor enabling a variable time and space related measurement of regional wall velocity from tissue Doppler images. Therefore, in 63 volunteers the mean velocity of a 2 mm thick subendocardial slice during the systolic ejection period was determined from frozen tissue Doppler M-mode images of the left ventricular posterior wall obtained using the left parasternal window. The same images were employed for comparative measurement of the mean endocardial velocity using the conventional M-mode slope approach. Tissue Doppler data of the subendocardial wall velocity were found to correspond closely to the mean endocardial wall velocity (y = 0.97x + 0.17; r = 0.77; p < 0.0001). The average wall motion gradient of the population was 1.33 +/- 0.35. Wall motion velocity and wall motion gradient were shown to be not age dependent. The new software approach to an improved analysis of wall motion offering any sized sample volumes and time intervals for wall velocity measurements can be regarded as an exact and easily feasible method. Further clinical and experimental investigations are needed to evaluate its diagnostic relevance to the detection of ischemia and other myocardial dysfunction.

Adolescent↗

PubMed2000

Regional brain volume abnormalities and long-term cognitive outcome in preterm infants.

CONTEXT: Preterm infants have a high prevalence of long-term cognitive and behavioral disturbances. However, it is not known whether the stresses associated with premature birth disrupt regionally specific brain maturation or whether abnormalities in brain structure contribute to cognitive deficits. OBJECTIVE: To determine whether regional brain volumes differ between term and preterm children and to examine the association of regional brain volumes in prematurely born children with long-term cognitive outcomes. DESIGN AND SETTING: Case-control study conducted in 1998 and 1999 at 2 US university medical schools. PARTICIPANTS: A consecutive sample of 25 eight-year-old preterm children recruited from a longitudinal follow-up study of preterm infants and 39 term control children who were recruited from the community and who were comparable with the preterm children in age, sex, maternal education, and minority status. MAIN OUTCOME MEASURES: Volumes of cortical subdivisions, ventricular system, cerebellum, basal ganglia, corpus callosum, amygdala, and hippocampus, derived from structural magnetic resonance imaging scans and compared between preterm and term children; correlations of regional brain volumes with cognitive measures (at age 8 years) and perinatal variables among preterm children. RESULTS: Regional cortical volumes were significantly smaller in the preterm children, most prominently in sensorimotor regions (difference: left, 14.6%; right, 14.3% [P<.001 for both]) but also in premotor (left, 11.2%; right, 12.6% [P<.001 for both]), midtemporal (left, 7.4% [P =.01]; right, 10.2% [P<.001]), parieto-occipital (left, 7.9% [P =.01]; right, 7.4% [P =.005]), and subgenual (left, 8.9% [P =.03]; right, 11.7% [P =.01]) cortices. Preterm children's brain volumes were significantly larger (by 105. 7%-271.6%) in the occipital and temporal horns of the ventricles (P<. 001 for all) and smaller in the cerebellum (6.7%; P =.02), basal ganglia (11.4%-13.8%; P</=.005), amygdala (left, 20.2% [P =.001]; right, 30.0% [P<.001]), hippocampus (left, 16.0% [P =.001]; right, 12.0% [P =.007]), and corpus callosum (13.1%-35.2%; P</=.01 for all). Volumes of sensorimotor and midtemporal cortices were associated positively with full-scale, verbal, and performance IQ scores (P<.01 for all). CONCLUSIONS: Our data indicate that preterm birth is associated with regionally specific, long-term reductions in brain volume and that morphological abnormalities are, in turn, associated with poorer cognitive outcome. JAMA. 2000;284:1939-1947.

Brain↗

PubMed1984

Intervening sequences in the ribosomal RNA genes of Ascaris lumbricoides: DNA sequences at junctions and genomic organization.

An rDNA size class in the genome of the nematode Ascaris lumbricoides is described which is interrupted by a 4.5-kb long intervening sequence located in the 26S coding region. This molecular form occurs in approximately 15 copies per haploid genome and amounts to approximately 5% of the total nuclear rDNA. Intervening sequences are present only in the 8.8-kb rDNA, but not in the 8.4-kb rDNA repeating units of A. lumbricoides. Cloning of the interrupted rDNA units revealed, in addition to the main 4.5-kb insertion, shorter intervening sequences of 4-kb and 119-bp length. Both shorter rDNA forms are present in the single copy range of the haploid genome. Sequence analyses of the intervening sequence/rDNA junctions show an identical right-hand junction for all of the three different rDNA forms. The two shorter intervening sequences are a coterminal subset of the right-hand end of the main 4.5-kb insertion, whereas all three insertions have a different left-hand junction with the coding region of rDNA. Each intervening sequence is flanked by a short direct repeat of variable length, being only once present in the uninterrupted rDNA. The intervening sequences of A. lumbricoides show striking similarity to the organization of type I insertion family in dipteran flies, even though they are inserted at different positions in the 26S coding region. Additional rDNA intervening sequences may be present outside of the rDNA cluster, but in not more than 15-20 homologous copies per haploid genome.

Animals↗

PubMed1975

In vivo localization of brain sulci by arteriography: a stereotactic anatomoradiological study.

The authors studied the course of the cortical arteries using the Talairach stereotactic system (orthogonal 4.8 m teleradiography, with rigid fixation of the skull in the stereotactic frame) in both anatomical specimens and normal bilateral carotid angiographies of epileptic patients. Anatomoradiological correlations between arterial patterns and underlying brain surface were identified by detailed 3-dimensional analysis of brain-skull preparations, where gyri and injected arteries were dissected progressively with stereotactic X-ray and photographic pictures taken at each step. The vascular landmarks so identified were studied in stereoscopic arteriographies that give a direct visualization of the spatial relationships of the arterial tree moulding the cortical surface thus allowing the recognition of the localization of the principal gyri and sulci. The latter were drawn on stereotactic diagrams. The basic sulcal pattern as shown by the arteries is strikingly symmetrical in both hemispheres of the same individual, in spite of variability in branching of the arterial tree. The disposition of the vascular landmarks in the retroinsular region reflects the left-right asymmetry of the planum temporale that can be recognized in vivo. This can give a clue to the study of anatomofunctional correlations with regard to speech dominance. A limited first series studied in this respect strongly suggests a close relationship between anatomical and functional asymmetry of the human cerebral hemispheres. Generally speaking, the authors feel that 3- dimensional, anatomical interpretation of angiography permits a direct localization of brain structures including the cortex, that can be used instead of indirect localization landmarks in stereotactic explorations, and further, that the wealth of anatomical information that can be drawn from angiography with their method may be helpful in diagnosis or for planning surgery.

Cerebral Angiography↗

PubMed2005

Hemispheric specialization for language: Brain volume matters.

Increasing brain volume may impose constraints, through longer information transfer delays, on the distributed networks supporting language. Here, we assessed the relative effects of brain volume and other putative predictors of the functional variability of perisylvian language areas, as probed with PET, during both a language comprehension and a language production task. In the case of language comprehension (story listening), a linear combination of planum temporale surface, brain volume and handedness could explain almost 60% of the functional asymmetry observed in the perisylvian area. Without brain volume, the goodness of fit was significantly decreased (39%, P < 0.05), and furthermore, the effect of handedness was not detected anymore. This was due to the fact that in our sample, left-handers (n = 12) had a significantly larger brain volume as compared to right-handers (n = 8, P = 0.03). As for language production (verb generation), brain volume and the planum temporale also played a role. However, in this case, the main predictor of functional variability was handedness, where a greater degree of right-handedness was associated with larger activation of left inferior frontal regions. Depending on the language component of interest, these results support different (yet compatible) theories on hemispheric specialization. Left specialization for comprehension could be attributed to the constraints of processing speech stimuli, while a gestural origin of language is mostly supported by the relation we observed between left specialization for production and right-handedness.

Adult↗

PubMed1985

Amelioration by nitroglycerin of left ventricular ischemia induced by percutaneous transluminal coronary angioplasty: assessment by hemodynamic variables and left ventriculography.

Increasingly longer balloon inflation times during coronary angioplasty can create significant left ventricular ischemia, amelioration of which was attempted in this study using nitroglycerin. Hemodynamic variables were assessed during inflation of an angioplasty balloon in the proximal left anterior descending coronary artery of 10 patients. Regional wall motion was assessed by left ventriculography during a separate balloon inflation. Nitroglycerin (200 micrograms) was then administered intravenously, and hemodynamic and ventriculographic assessments during balloon inflations were repeated. Balloon inflation resulted in a marked increase in left ventricular end-diastolic pressure (from 9.2 +/- 2.1 to 19.4 +/- 2.9 mm Hg) and time constant of left ventricular relaxation (from 44.2 +/- 6.2 to 62.3 +/- 11.3 ms) and a decrease in distal coronary artery perfusion pressure (from 54 +/- 9 to 33.1 +/- 4 mm Hg). Time to onset of angina was 29 +/- 3 seconds and time to ST segment depression of 1 mm or greater was 30 +/- 3 seconds. Regional wall motion analysis 30 seconds after onset of balloon inflation revealed marked hypokinesia and akinesia in the anteroapical segments with graduated depression of inferior wall motion, greatest at the apex. After the administration of nitroglycerin, balloon inflation resulted in a smaller increase in end-diastolic pressure (from 5.0 +/- 2.7 to 8.3 +/- 2.6 mm Hg) and time constant (from 47.9 +/- 4.7 to 54.4 +/- 9.2 ms; both p less than 0.01 versus standard balloon inflation). Distal coronary artery pressure remained similar to standard balloon inflation (32 +/- 3 mm Hg) despite lower mean arterial pressure (89 +/- 5 mm Hg, p less than or equal to 0.01).(ABSTRACT TRUNCATED AT 250 WORDS)

Aged↗

PubMed1996

Assessment of myocardial reinnervation in cardiac transplants by positron emission tomography: functional significance tested by heart rate variability.

While it is known that scintigraphically measured uptake of [C-11] hydroxyephedrine (HED) correlates well with the catecholamine uptake and storage in the nerve terminals of the myocardium, the functional significance of this morphologic marker remains unclear. It had been shown that normal, innervated myocardium exhibits pronounced heart rate variability (HRV). In this study, parallel to the scintigraphic determination of regional HED uptake, the functional sympathetic innervation of the left ventricle was measured by spectral analysis of HRV. Prior to PET scanning, changes in the low frequency HRV after tilt were determined as validated marker of sympathetic function in 12 patients with cardiac transplants (mean time after transplantation 4.7 years). Dynamic PET data acquisition allowed the definition of a retention index as regional marker for sympathetic nerve terminals. Intensity as well as regional extent of this marker were then compared to the results of HRV studies. Two groups were defined based on the scintigraphic findings: 8 of 12 patients displayed regionally increased HED retention (11.5 +/- 3.1%/min.) in the anteroseptal region of the left ventricle, while 4 patients showed little HED uptake (4.3 +/- 0.5%/min.). Uptake values tended to increase for longer times after surgery. Average HRV in the first group (7.57 +/- 7.47 ms2/Hz) was significantly higher (p < 0.05) compared to the low HED uptake group (1.17 +/- 1.08 ms2/Hz). HRV was lower than normal values even in the first group. These independent electrophysiological measurements prove the significance of HED retention for the functional characterization of reinnervation in cardiac transplants.

Adult↗

PubMed1995

Pear blister canker viroid: sequence variability and causal role in pear blister canker disease.

The sequences of several cDNA clones of pear blister canker viroid (PBCVd) P1914T and P47A isolates have been determined. Seven out of eight P1914T clones analysed have a constant sequence which differs at six positions from that of the P2098T isolate reported previously. The remaining P1914T clone (8) has a single nucleotide substitution. The same six changes have been also observed in most of the ten P47A clones sequenced. However, some P47A clones show additional variability in positions on both strands of the central conserved region (CCR) and in another conserved sequence at the left-terminal region. This is the first report of a change affecting the upper strand of a viroid CCR. Reasons why such a change is tolerated are discussed. Infectivity bioassays have demonstrated that PBCVd is the causal agent of PBC disease.

Base Sequence↗