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PubMed1994

Influence of reversible segmental left ventricular dysfunction on heart period variability in patients with one-vessel coronary artery disease.

OBJECTIVES: This study evaluated the relation between reversible segmental left ventricular dysfunction and frequency domain measures of heart period variability in patients with coronary artery disease. BACKGROUND: Heart period variability is frequently reduced in patients with coronary artery disease. However, the mechanisms of this reduction are still unclear. METHODS: Echocardiographic left ventricular wall motion and frequency domain measures of heart period variability were evaluated in 32 patients with one-vessel coronary artery disease before and 16 to 24 days after successful percutaneous transluminal coronary angioplasty. Of these, 12 patients (Group A) had normal and 20 patients (Group B) had abnormal regional wall motion. A control group of 15 healthy subjects (Group C) underwent 24-h Holter recording twice at 2-week intervals to check for spontaneous variations. RESULTS: At baseline, low and high frequency power were lower in Group B than in Groups A and C, whereas no difference was detectable in ultra low and very low frequency and total power. After coronary angioplasty, regional wall motion and frequency domain measures of heart period variability were unchanged in Group A. In Group B the mean (+/- SD) summed segment score improved from 17.1 +/- 3.6 to 12.8 +/- 2.0 (p < 0.01), and mean low and high frequency power (logarithmic units) increased from 6.14 +/- 0.23 to 6.35 +/- 0.34 (p < 0.01) and from 5.43 +/- 0.32 to 5.68 +/- 0.52 (p < 0.01), respectively. Furthermore, low and high frequency power, lower at baseline in Group B than in the other two groups, were comparable in the three groups after coronary angioplasty. CONCLUSIONS: This study demonstrates that segmental left ventricular dysfunction is involved in determining sympathovagal imbalance in patients with one-vessel coronary artery disease; the reversal of left ventricular dysfunction by successful coronary angioplasty improves the heart period power spectrum. Thus, alterations in cardiac geometry influence the discharge of afferent sympathetic mechanoreceptors, contributing to the derangement in autonomic control of heart rate.

Afferent Pathways↗
PubMed1998

Regulation of pathogenicity in hop stunt viroid-related group II citrus viroids.

Nucleotide sequences were determined for two hop stunt viroid-related Group II citrus viroids characterized as either a cachexia disease non-pathogenic variant (CVd-IIa) or a pathogenic variant (CVd-IIb). Sequence identity between the two variants of 95.6% indicated a conserved genome with the principal region of nucleotide difference clustered in the variable (V) domain. Full-length viroid RT-PCR cDNA products were cloned into plasmid SP72. Viroid cDNA clones as well as derived RNA transcripts were transmissible to citron (Citrus medica L.) and Luffa aegyptiaca Mill. To determine the locus of cachexia pathogenicity as well as symptom expression in Luffa, chimeric viroid cDNA clones were constructed from segments of either the left terminal, pathogenic and conserved (T1-P-C) domains or the conserved, variable and right terminal (C-V-T2) domains of CVd-IIa or CVd-IIb in reciprocal exchanges. Symptoms induced by the various chimeric constructs on the two bioassay hosts reflected the differential response observed with CVd-IIa and -IIb. Constructs with the C-V-T2 domains region from clone-IIa induced severe symptoms on Luffa typical of CVd-IIa, but were non-symptomatic on mandarin as a bioassay host for the cachexia disease. Constructs with the same region (C-V-T2) from the clone-IIb genome induced only mild symptoms on Luffa, but produced a severe reaction on mandarin, as observed for CVd-IIb. Specific site-directed mutations were introduced into the V domain of the CVd-IIa clone to construct viroid cDNA clones with either partial or complete conversions to the CVd-IIb sequence. With the introduction of six site-specific changes into the V domain of the clone-IIa genome, cachexia pathogenicity was acquired as well as a moderation of severe symptoms on Luffa.

Base Sequence↗
PubMed1996

Renal resistive indexes: variability in Doppler US measurement in a healthy population.

PURPOSE: To determine the variability in resistive index (RI) in normal kidneys, possible causes of variability, and consequences of reporting a single value. MATERIALS AND METHODS: Doppler ultrasound RI measurements were obtained in the upper, middle, and lower regions of 118 kidneys in 58 healthy subjects (aged 24-70 years; 35 women, 23 men) who subsequently underwent angiography. The effects of sampling a particular parenchymal region, vascular territory, or kidney were assessed. RESULTS: Kidney region, vascular territory, and right versus left kidney had no consistently significant effect (P < or = .05) on RI. Age had a statistically significant effect. RI readings were highly correlated with each other both within a subject and within a kidney. The probability that a single RI value would exceed 0.70 in a healthy 45-year-old subject was 6%; this decreased to 3% when three readings were averaged. CONCLUSION: The variability of RI measurements in a kidney suggests that a number of RI readings should be averaged before a single representative value is reported.

Adult↗
PubMed1987

Biomathematics of intracranial CSF and haemodynamics. Simulation and analysis with the aid of a mathematical model.

A mathematical model of the isolated intracranial system including autoregulation of cerebral blood flow with the aid of a variable cerebrovascular resistance is described. The rate of formation of cerebrospinal fluid is assumed to depend on the regional blood flow through the choroid plexuses. This model is extended by cardiovascular components including the left ventricle of the heart, the aorta and the peripheral resistance. Additionally the model contains control circuits to simulate the short-time behaviour of the blood pressure regulation with the aid of the baroreceptor reflex. Disturbances of central regulation of blood pressure are simulated depending on changes of the regional blood flow through the brain stem. The application of the model is demonstrated by the analysis of the influence of arterial blood pressure upon the intracranial pulse pressure relationship (PPR) and upon the pressure response to a volume pressure test. Theoretical considerations and simulations reveal an opposite effect of arterial blood pressure (ABP) and its amplitude upon PPR. The ICP amplitude rises with decreasing ABP or increasing ABP amplitude. Breakpoints and other deviations from a linear PPR over the whole ICP range are studied by the analysis of the transfer function. The application of the model concerning parameter estimation methods is demonstrated and discussed. Simulations of rhythmic phenomena with the aid of the extended model point out possible approaches to quantitative descriptions of disturbances of central regulation.

Brain↗
PubMed1982

A pair of descending neurons with dendrites in the optic lobes projecting directly to thoracic ganglia of dipterous insects.

The lobula descending neuron (LDN) of dipterous insects is a unique nerve cell (one on each side of the brain) that projects directly from the lobula complex of the optic lobes to neuropil in thoracic ganglia. In the supraoesophageal ganglia the LDN has two prominent groups of branches of which at least one is dendritic in nature. Postsynaptic branches are distributed in the lobula and some branches, the synaptic relations of which are not yet known, extend to the lobular plate. A second group of branches is found among dendrites of the descending neurons proper, in the lateral midbrain. The arborization of LDN in the lobular (and lobula plate) map onto a retinotopic neuropil region subserving a posterior strip of the visual field of the compound eye. The arborizations in the lobula complex are extremely variable in size. The numbers of dendritic spines they possess vary greatly between left and right optic lobes of one animal, and between individual animals.

Animals↗
PubMed2006

The influence of site of collection on postmortem morphine concentrations in heroin overdose victims.

When assaying for postmortem morphine concentration, significant site sampling variability exists between central and peripheral sampling sites and even within sampling regions of the body. To study the variation, 76 suspected heroin overdoses were identified. Each had femoral artery (FA) and vein (FV), left and right ventricle and pooled heart blood samples obtained at autopsy. Forty-four tested positive for morphine. Morphine concentrations were determined by gas chromatography/mass spectrometry, with sampling site differences reported as log-transformed ratios and compared by signed rank test. The mean FA to FV ratio for total morphine was 1.2 (range 0-4.5). The ratio for left heart to right heart total morphine was 1.1 (range 0.4-3.2). Left ventricular to FV total morphine ratio was 2.0 (range 0.6-6.9). In these opioid overdose deaths, FA and FV morphine concentrations are usually similar, although up to 4.5-fold differences were noted. Centrally obtained morphine concentrations are on average twice as high compared with peripheral morphine concentrations. Left and right ventricular morphine concentrations were usually similar, although up to 3.2-fold differences were noted (left side higher).

Adolescent↗
PubMed1994

Impaired left ventricular filling rate induced by treatment with recombinant interleukin 2 for advanced cancer.

BACKGROUND: Immunotherapy with recombinant interleukin 2 (rIL 2) has been extensively used to treat cancer but its use has been hampered by serious side effects including severe hypotension, arrhythmias, and myocardial infarction. OBJECTIVE: To assess the effects of rIL 2 on human left ventricular function. METHODS: Left ventricular (LV) function was monitored in 22 patients (9 women, 13 men) (mean (SD) age 53 (10) years) undergoing a 120 h continuous intravenous infusion of rIL 2 (18 x 10(6) IU/m2/day) for melanoma (4), renal cell (16), ovarian (1), and colon cancer (1). Radionuclide ventriculography was performed before and 1 h after the end of treatment. Ejection fraction (EF), peak emptying rate (PER), peak filling rate (PFR), and regional left ventricular wall motion were analysed. Heart rate (HR), central venous pressure (CVP), systolic (SBP) and diastolic blood pressures (DBP), the electrocardiogram, and myocardial enzyme concentrations were monitored throughout the study. RESULTS: All variables (mean (SD)) were normal before rIL 2 was given. After rIL 2 administration HR increased significantly from 84 (11) to 125 (18) beats/min (p < 0.0001), SBP fell from 128 (11) to 100 (9) mmHg (p < 0.001) and DBP from 76 (9) to 65 (7) mmHg (p < 0.0001). CVP decreased from 3.70 (3.2) to 1.30 (0.45) cm H2O (p < 0.001). EF (65 (7) to 64 (8%) and PER (3.56 (0.60) to 3.86 (0.83) EDV/s) did not change significantly. PFR decreased significantly at the end of the rIL 2 infusion from 2.68 (0.46) to 2.37 (0.43) EDV/s (p < 0.01). Left ventricular segmental hypokinesia developed in 6 patients. Myocardial enzyme concentrations remained normal throughout the study. CONCLUSIONS: The results of this study confirmed that rIL 2 produces important haemodynamic changes, predominantly related to decreased systemic resistance. However, the observed reduction in PFR in most patients suggested that rIL 2 might exert its action at the level of the heart muscle itself. The localised systolic dysfunction in some patients suggested that rIL 2 might also adversely affect myocardial perfusion.

Blood Pressure↗
PubMed2003

Elucidating the molecular mechanism of cardiac remodeling using a comparative genomic approach.

It is proposed that analysis of global gene expression would provide an understanding of the molecular mechanisms of cardiac remodeling. However, previous studies have only provided "snapshots" of differential gene expression. Furthermore, the differences in gene expression between regions of the heart that can result in sampling variability have not been characterized. In this study, we employed the Affymetrix GeneChip technology to evaluate the patterns of expression in two different in vivo models of cardiac remodeling and in two different regions (left ventricle free wall and intraventricular septum) of the heart. Mice underwent transverse aortic constriction (TAC), myocardial infarction (MI), or sham operation, and RNA from the left ventricle free wall and the septum was isolated 1 wk later. Histological analysis showed profound myocyte hypertrophy and fibrosis in both the septum and the left ventricle free wall of the TAC model, whereas, in the MI model, only the left ventricle exhibited hypertrophy. These differences were also reflected in the expression analysis. In conclusion, our analysis shows that regional differences in gene expression exist in the heart. Moreover, common pathways that are coregulated in both models exist, and these might be central to the hypertrophic phenotype regardless of the initial hypertrophic stimuli.

Animals↗
PubMed2005

Assessment of atrial regional and global electromechanical function by tissue velocity echocardiography: a feasibility study on healthy individuals.

BACKGROUND: The appropriate evaluation of atrial electrical function is only possible by means of invasive electrophysiology techniques, which are expensive and therefore not suitable for widespread use. Mechanical atrial function is mainly determined from atrial volumes and volume-derived indices that are load-dependent, time-consuming and difficult to reproduce because they are observer-dependent. AIMS: To assess the feasibility of tissue velocity echocardiography (TVE) to evaluate atrial electromechanical function in young, healthy volunteers. SUBJECTS AND METHODS: We studied 37 healthy individuals: 28 men and nine women with a mean age of 29 years (range 20-47). Standard two-dimensional (2-D) and Doppler echocardiograms with superimposed TVE images were performed. Standard echocardiographic images were digitized during three consecutive cardiac cycles in cine-loop format for off-line analysis. Several indices of regional atrial electrical and mechanical function were derived from both 2-D and TVE modalities. RESULTS: Some TVE-derived variables indirectly reflected the atrial electrical activation that follows the known activation process as revealed by invasive electrophysiology. Regionally, the atrium shows an upward movement of its walls at the region near the atrio-ventricular ring with a reduction of this movement towards the upper levels of the atrial walls. The atrial mechanical function as assessed by several TVE-derived indices was quite similar in all left atrium (LA) walls. However, all such indices were higher in the right (RA) than the LA. There were no correlations between the 2-D- and TVE-derived variables expressing atrial mechanical function. Values of measurement error and repeatability were good for atrial mechanical function, but only acceptable for atrial electrical function. CONCLUSION: TVE may provide a simple, easy to obtain, reproducible, repeatable and potentially clinically useful tool for quantifying atrial electromechanical function.

Atrial Function↗
PubMedDate not supplied

Ultrasonographic assessment of regional radial and longitudinal systolic function in healthy awake dogs.

BACKGROUND: Strain (St) and strain rate (SR) imaging are new ultrasound modalities based on tissue Doppler imaging (TDI) that allow quantitative assessment of segmental myocardial contraction or stretching and rate of deformation, respectively. HYPOTHESIS: Regional peak systolic St and SR could allow repeatable and reproducible assessment of systolic function of the right (RVW) and left (LVFW) myocardial walls in dogs. ANIMALS: Six healthy Beagle dogs were used to determine the repeatability and reproducibility of regional peak systolic St and SR in the RVW and LVFW (Study 1). These variables were also assessed in 30 healthy dogs of several breeds (Study 2). METHODS: Longitudinal peak systolic St and SR were recorded in 2 segments (basal and apical) of the RVW and LVFW. Radial peak systolic St and SR of the LVFW were also assessed. RESULTS: All within- and most (7/10) between-day coefficients of variation were <15%. Absolute values of the longitudinal deformation indices were significantly higher (P < .001) in the RVW (St = -39.5 +/- 5.5% and SR = -5.2 +/- 0.8 s(-1) at the base; St = -36.3 +/- 4.3% and SR = -4.7 +/- 1.1 s(-1) at the apex) than in the LVFW. Absolute values were also higher for the radial (St = 62.9 +/- 10.4% and SR = 5.8 +/- 1.1 s(-1), P < .001) than for the longitudinal LFVW motions. CONCLUSIONS AND CLINICAL IMPORTANCE: St and SR imaging is a repeatable and reproducible method for assessing systolic myocardial function. The combination of these indices with conventional echocardiographic variables may be useful for screening canine myocardial diseases.

Animals↗
PubMed1985

The effects of atrial fibrillation on myocardial blood flow and energetics.

The changes produced by atrial fibrillation on myocardial blood flow and energetics are unclear. Accordingly, the effects of atrial fibrillation on myocardial blood flow and oxygen consumption were studied in 18 anesthetized dogs. With atrial fibrillation cardiac output and mean aortic pressure declined. Although average myocardial blood flow and oxygen consumption did not change, the alterations in these variables correlated strongly (r = 0.95, P less than 0.01). Moreover, myocardial blood flow changes correlated with those of tension time index and peak dp/dt (r = 0.64, P less than 0.05). Distribution of left ventricular regional flow remained uniform irrespective of the directional changes in blood flow. However, average left ventricular inner to outer wall flow ratio declined and myocardial oxygen extraction increased. Thus, with atrial fibrillation, myocardial blood flow does not change in a consistent fashion, although myocardial blood flow still reflects myocardial oxygen demand. Relative hypoperfusion of subendocardium and an increase in myocardial oxygen extraction suggest that with atrial fibrillation the myocardial blood flow response is abnormal.

Animals↗
PubMed2002

Diffusion-weighted imaging and apparent diffusion coefficient maps in a case of intracerebral abscess with ventricular extension.

Previous findings have demonstrated the diagnostic usefulness of diffusion-weighted imaging in depicting specific features of a brain abscess. We report a case of a cerebral abscess, which ruptured into the ventricular system, including its findings on both diffusion-weighted images and apparent diffusion coefficient (ADC) maps. Purulent material within the left lateral ventricle, similar to that of the central abscess cavity, was strongly hyperintense on diffusion-weighted images. However, variable signal intensity changes were observed on the ADC map; these probably corresponded to regional variation of the concentration of protein in the purulent material. In this case, both diffusion-weighted images and ADC maps were important and complementary in the evaluation of ventricular extension of an intracerebral abscess.

Aged↗
PubMed1988

Lack of correlation between anatomic infarct size and ventriculographic variables following coronary occlusion in closed-chest dogs.

1. Although the effects of therapeutic interventions upon infarct size are frequently assessed on the basis of left ventricular ejection fraction and segmental contraction, the correlation of these variables with infarct size has not been thoroughly evaluated. To explore such relationships, we occluded the left anterior descending coronary artery of 22 closed-chest dogs and performed contrast ventriculography one week later. Regional myocardial function was evaluated by a computer system in 60 radial segments. 2. Infarct size, measured by triphenyl-tetrazolium chloride staining, ranged from 1.4 to 43.6% of the left ventricle. Infarcted dogs were arbitrarily divided into 3 groups by percentage of necrotic area: Group 1 (less than or equal to 15%, N = 5), Group 2 (15 to 30%, N = 10) and Group 3 (greater than or equal to 30%, N = 7). 3. Although the ejection fraction was significantly reduced in infarcted animals as compared to preselected normal controls (38.9 +/- 11.6 [SD] vs 74.1 +/- 7.5%, P less than 0.001), it was similar within each infarct subgroup. 4. There was a linear inverse correlation between ejection fraction and percentage of abnormally contracting segments (R = -0.63, P = 0.0017). However, neither ejection fraction nor abnormally contracting segments were correlated with infarct size (R = -0.17 and R = 0.11, respectively). 5. A more detailed analysis revealed that infarcted or infarct-adjacent segments were less depressed in Group 1 than in Group 2 or 3 and extent of depression was similar between Groups 2 and 3. Conversely, the extent of shortening of non-infarcted inferior wall segments increased from Group 1 to Group 3. 6. Thus, regional myocardial contraction is significantly affected by non-necrotic infarct-adjacent segments and the ejection fraction is significantly influenced by non-ischemic myocardium. For infarcted areas up to 40% of the left ventricle, a single post-infarction determination of ejection fraction or the percentual of abnormally contracting segments seems unreliable, on a population basis, to judge the effects of infarct-sparing interventions.

Animals↗
PubMed2006

Morphologic asymmetry of the human anterior cingulate cortex.

The anterior cingulate cortex (ACC) is thought to play a major role in executive processes. Studies assessing neuroanatomical attributes of this region report a high degree of morphological variability. Recent theories consider the fissurization of the cortex to be a product of gross mechanical processes related to cortical growth and local cytoarchitectural characteristics. Hence, local sulcal patterning and gray matter volume are supposed to be associated. ACC fissurization was quantified in left- and right-handers of both sexes by recording the presence and extension of the paracingulate sulcus (PCS). Differences between groups regarding local gray matter volume were assessed by means of optimized voxel-based morphometry (oVBM) including additional modulation. Overall, the PCS occurred more often and was more pronounced in the left as compared to the right anterior cingulate region, although hemispheric differences were less pronounced in male left- and female right-handers. These discrepancies between groups seem to stem from variations of cingulate morphology in the left rather than the right hemisphere. The pattern of relevant comparisons in the oVBM analysis indicated a similar interaction. Therefore, evidence was found for discrepancies between groups and hemispheres on the macrostructural level.

Adult↗
PubMed1990

A new method for noninvasive quantitation of segmental myocardial wall thickening using technetium-99m 2-methoxy-isobutyl-isonitrile scintigraphy--results in normal subjects.

A quantitative index of regional myocardial wall motion obtained from electrocardiogram-gated perfusion images has been assessed. The assumption for the proposed algorithm is that, according to the partial volume effect, the recovery counts by the instrumentation is a function of the object size. Systo-diastolic changes in the detected radioactivity would therefore reflect changes in myocardial wall thickness. Ten normal volunteers were studied in control condition by 99mTc 2-methoxy-isobutyl-isonitrile scintigraphy. Electrocardiogram (ECG)-gated images were acquired in multiple projections. End-diastolic and end-systolic activity was measured along radii from the center to the edge of the left ventricle. Data are displayed as circumferential profiles and the percent systolic thickening determined according to the formula (end-systolic profile--end-diastolic profile) (end-diastolic profile + background) x 100.) The intra- and interobserver variabilities were +/- 5.4% and +/- 4.1%, respectively. Analysis of regional systolic thickening showed a heterogeneous pattern, with a maximal and minimum value of 35% and 27% located to the infero-apical and to the proximal anterior wall, respectively. Our values correlate well with those reported for normals using cine computed tomography or nuclear magnetic resonance.

Adult↗
PubMed1994

Three-dimensional structures of the neck region of the hamster spermatozoa in the caudal epididymis.

Three-dimensional structures of the capitulum and first mitochondria in the neck region of the hamster spermatozoa, were observed with transmission (TEM) and scanning electron microscope (SEM). Some capitula revealed a variable contour even in the caudal epididymis, but most finally developed to form a typical wagonette shape. The final shape of the capitulum is probably produced by the aid of apical protrusion of the right, pyramidal mitochondrium. The right and left first mitochondria were triangular pyramids in contour, while the dorsal and ventral ones were rod-like in shape. The mutual transformations between the capitulum and the first mitochondria are discussed in relation to the completion of the neck region.

Animals↗
PubMed2000

Cardiac autonomic neuropathy in patients with chronic renal failure on hemodialysis.

To characterize uremic cardiac autonomic neuropathy, we measured plasma catecholamines, analyzed the 24-hour heart rate variability (HRV), and acquired serial images with (123)I-metaiodobenzylguanidine (MIBG) in 44 patients with chronic renal failure on hemodialysis and in 14 controls. Time-domain measures were calculated using the Marquette HRV program. MIBG clearance rates from the heart and lung were evaluated on planar images, and the regional MIBG uptake in the left ventricular myocardium was evaluated with single-photon emission computed tomography. Compared with controls, plasma dopamine and norepinephrine levels were elevated (p < 0.001 and p = 0.03, respectively), and all the time-domain measures of HRV were reduced in the patients (p < 0.001). The MIBG clearance rate from the heart was higher (p < 0.001), that from the lung was lower (p < 0.001), and the myocardial MIBG distribution was more heterogeneous in patients than in controls (total uptake score p </= 0.03). These variables were similar between 26 patients without and 18 patients with hypertension. Uremic cardiac autonomic neuropathy may be characterized by high plasma levels of dopamine and norepinephrine, reduced HRV, and abnormal MIBG kinetics in the heart with heterogeneous myocardial MIBG distribution, suggesting cardiac sympathetic overactivity and parasympathetic deterioration. In addition, abnormal MIBG kinetics in the lung may imply pulmonary sympathetic nervous dysfunction and/or endothelial dysfunction in uremic patients.

3-Iodobenzylguanidine↗