PubMed Health⌕ Search

SEARCH · PubMed Health

Results for “left variable region”

Explore indexed PubMed citations for clinical trials, systematic reviews and public health research. Read source abstracts and follow each citation to its original PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 37 records · Page 2Linked to original sources
PubMed2001

A variable region on the chlorovirus CVK2 genome contains genes possibly involved in the host range determination.

A 22.6-kbp variable region near the left end of the chlorovirus CVK2 genome which was characterized. This region contained a tandem array of 5 gene copies for Vp260-like protein, a viral surface glycoprotein. The authentic 104-kDa Vp260 was encoded at another site on the genome and contained 13 internally located, tandem repeats of 61-65 amino acids like the prominent Rickettsia surface antigen. By Northern and Western blot analyses, these genes were demonstrated to be expressed late in infection and the proteins were incorporated into virions. These results implied that the extra copies of Vp260-like proteins may be involved in host range in the natural environment.

Gene Dosage↗
PubMed1983

Estimation of absolute left ventricular volume from gated radionuclide ventriculograms. A method using phase image assisted automated edge detection and two-dimensional echocardiography.

Twenty-four patients underwent gated cardiac blood pool (GBP) imaging, two-dimensional echocardiography (2-D echo), and single-plane contrast ventriculography (within 24 hours). Variable left ventricular (LV) regions of interest on GBP images were identified by an automated threshold radial search. To avoid excluding LV counts we indexed the search threshold to the threshold identified by a phase image generated by Fourier analysis. LV depth calculated by 2-D echo was used for attenuation correction of LV counts. LV end-diastolic volume (EDV) and end-systolic volume (ESV) were calculated by dividing attenuation, background and deadtime corrected LV count rates by the background corrected count rate/ml of venous blood drawn during the study. Correlations between radionuclide and contrast volumes were good (EDV + ESV r = 0.97, EDV r = 0.94, ESV r = 0.95). Regression lines were close to the lines of identity. This method, in which GBP imaging and automated LV edge finding are complemented by 2-D echo for count attenuation correction, demonstrated reliable and reproducible noninvasive estimates of absolute LV volume.

Adult↗
PubMed1989

Longitudinal evaluation of left ventricular performance in dogs following nonpenetrating cardiac trauma.

To investigate the temporal changes of global left ventricular function following nonpenetrating cardiac impact, studies were performed in ten purpose-bred dogs. Under full anesthesia and after hemodynamic and angiographic measurement, a midline thoracotomy was performed and a 12 m/sec blunt impact was delivered to the anterior surface of the heart in eight dogs with an air-pressurized impactor. Two dogs were sham operated and did not undergo trauma. After closing the chest, the hemodynamic measurements were repeated at 3 hours, 3 days, 2 weeks, and 5 weeks after impact. Hemodynamic measurements included left ventricular end-diastolic pressure and peak left ventricular positive and negative rates of change of pressure. Left ventricular ejection fraction was calculated from ventriculograms obtained with the dog positioned on its right side. All indices of left ventricular performance in dogs that underwent trauma were depressed at 3 hours after impact and recovered gradually to near normal levels at 2 to 5 weeks after trauma. Recovery of left ventricular function occurred in spite of residual patchy scarring of the left ventricular myocardium in the region of impact. No variability of left ventricular function indices was observed over the course of the study in the two sham-operated dogs. The results indicate that blunt cardiac impact can cause depression of left ventricular performance in the immediate post-impact period, but near complete recovery of function occurs within 2 to 5 weeks after the injury, in spite of residual scarring.

Animals↗
PubMed1987

Subjective analysis of cross-sectional echocardiograms: reproducibility and sources of variability.

Subjective analysis of left ventricular segmental wall motion is widely used to assess regional left ventricular function and the effects of intervention in patients with ischaemic heart disease. To determine its reproducibility we studied 20 consecutive men with proven ischaemic heart disease and 10 age-matched control subjects. Standard parasternal, apical and subcostal views were attempted in all subjects by two echocardiographers, and echoes were reported by two analysers, each on two occasions. The left ventricle was subdivided into 5 segments, and segmental wall motion scored as normal, hypokinetic, akinetic, dyskinetic or inadequately visualised. The different sources of variability were evaluated. The echocardiographers contributed little variability, the frequency and reproducibility of reporting being the same for echoes produced by each echocardiographer. The only exception was for subcostal views in which one echocardiographer produced significantly more reportable segments than the other (42% vs 27%; P less than 0.001). Within and between analyser variability was large. Replicate analysis of the same segment showed within analyser agreement of 92% for one analyser but only 80% for the other. Between analyser agreement was 89% for some segments but only 63% for others and was best in those segments where both analysers infrequently reported abnormal wall motion. Reporting bias is thus an important variable. The subjective assessment of regional left ventricular function thus has major limitations for general applications particularly when being used in longitudinal studies.

Coronary Disease↗
PubMed1987

Quantification of left-ventricular regional dyssynergy by radionuclide angiography.

To determine whether variables obtained from Fourier analysis of gated equilibrium radionuclide angiographic (RNA) images can detect and quantify changes in left-ventricular (LV) regional wall motion induced by transient ischemia, 11 chronically instrumented dogs were simultaneously studied with hemodynamic measurements and RNA during control, left circumflex (LCx) coronary artery occlusion, and postocclusion conditions. The dogs were preinstrumented with aortic and LV catheters, electromagnetic aortic and LCx coronary artery flow probes, high-fidelity LV micromanometers, LCx coronary artery occluders, and 4-mm ultrasonic transverse LV diameter and 2-mm regional LV segment crystal pairs. Radionuclide LV regional phase and amplitude variables were calculated for each condition. The absolute changes in LCx region RNA mean, median, and standard deviation of mean phase correlated with the percent changes in LCx segment crystal fractional shortening (r = -0.71, -0.64, and -0.51, respectively; all p less than or equal to 0.01). Similarly, the absolute changes and percent changes in LCx region RNA mean amplitude per pixel correlated with the percent changes in LCx segment crystal fractional shortening (r = 0.89 and 0.94, respectively; both p less than 0.001). When these LCx region RNA phase variables were subgrouped according to mild or severe depression or augmentation in LCx segment crystal fractional shortening, progressive differences were observed between the average values for these subgroups (p less than 0.05 to p less than 0.001). These data, therefore, suggest that these regional RNA phase variables may be able to detect and quantify alterations in LV contraction patterns due to transient ischemia.

Animals↗
PubMed1997

The effect of normalization in reducing variability in regional wall thickening.

This study was performed to evaluate a new method for measuring regional left ventricular wall thickening in terms of its variability, normal range, and diagnostic sensitivity. Two-dimensional echocardiographic images in the parasternal short-axis view of 44 normal patients and 17 patients with recent myocardial infarction were analyzed. Regional wall thickness was measured according to the centerline method at 100 chords. Wall thickening at each chord i was calculated as the change in wall thickness between end diastole and end systole at chord i, normalized by the average end-diastolic thickness of the wall segment extending from chord (i - n) to chord (i + n). Five widths of the normalization segment, defined as (2n + 1), were tested: 1 (baseline method), 5, 11, 15, and 21 chords. Widening the normalization segment significantly reduced point-to-point variability by up to 20% (p = 0.0001) evenly over the entire left ventricular contour. The magnitude of reduction approached a plateau at a normalization segment width of 11 chords. The normal mean and standard deviation for regional wall thickening were also reduced slightly but significantly in a progressive and uniform manner. The apparent severity of hypokinesis worsened by up to 0.1 +/- 0.1 SD (p = 0.006) as the normalization segment was widened. The circumferential extent of hypokinesis was not lengthened significantly until the normalization segment was 21 chords wide. The magnitude of hyperkinesis was unchanged. Normalizing over a wider segment of the myocardium reduces variability in the measurement of wall thickening, widens the separation between normal patients and those with disease, and enhances the diagnostic accuracy of quantitative two-dimensional echocardiography. The optimal normalization segment width is 11 chords.

Echocardiography↗
PubMed1986

Functional and anatomical variability of canine cardiac sympathetic efferent pathways: implications for regional denervation of the left ventricle.

To further elucidate the functional anatomy of canine cardiac innervation as well as to assess the feasibility of producing regional left ventricular sympathetic denervation, the chronotropic and (or) regional left ventricular inotropic responses produced by stellate or middle cervical ganglion stimulation were investigated in 22 dogs before and after sectioning of individual major cardiopulmonary or cardiac nerves. Sectioning the right or left subclavian ansae abolished all cardiac responses produced by ipsilateral stellate ganglion stimulation. Sectioning a major sympathetic cardiopulmonary nerve, other than the right interganglionic nerve, usually reduced, but seldom abolished, regional inotropic responses elicited by ipsilateral middle cervical ganglion stimulation. Sectioning the dorsal mediastinal cardiac nerves consistently abolished the left ventricular inotropic responses elicited by right middle cervical ganglion stimulation but minimally affected those elicited by left middle cervical ganglion stimulation. In contrast, cutting the left lateral cardiac nerve decreased the inotropic responses in lateral and posterior left ventricular segments elicited by left middle cervical ganglion stimulation but had little effect on the inotropic responses produced by right middle cervical ganglion stimulation. In addition, the ventral mediastinal cardiac nerve was found to be a significant sympathetic efferent pathway from the left-sided ganglia to the left ventricle. These results indicate that the stellate ganglia project axons to the heart via the subclavian ansae and thus effective sympathetic decentralization can be produced by cutting the subclavian ansae; the right-sided cardiac sympathetic efferent innervation of the left ventricle converges intrapericardially in the dorsal mediastinal cardiac nerves; and the left-sided cardiac sympathetic efferent innervation of the left ventricle diverges to innervate the left ventricle by a number of nerves including the dorsal mediastinal, ventral mediastinal, and left lateral cardiac nerves. Thus consistent denervation of a region of the left ventricle can not be accomplished by sectioning an individual cardiopulmonary or cardiac nerve because of the functional and anatomical variability of the neural components in each nerve, as well as the fact that overlapping regions of the left ventricle are innervated by these different nerves.

Animals↗
PubMed1999

[Improved assessment of the left ventricular endocardial border by intravenous injection of a left heart contrast agent].

PURPOSE: The purpose of this study was to find out whether intravenous injection of a phospholipid-based left heart echo contrast agent improves the delineation of the left ventricular endocardial border. The influence of echo contrast on the quantification of left ventricular volumes, ejection fraction, regional wall function and interobserver variability was also assessed. METHOD: Prospectively, the apical 4-chamber view was recorded in 20 adult patients before and after intravenous injection of the contrast agent. Left ventricular endocardial border resolution was assessed in 5 segments and left ventricular volumes, ejection fraction, regional wall motion and interobserver variability were measured. RESULTS: After contrast injection a diagnostically useful left ventricular opacification was present in 18 patients (90%) and an optimal opacification in 14 patients (70%). Without contrast 1.05 endocardial segments could be delineated at end diastole and 1.8 segments at end systole. After contrast injection 3.65 endocardial segments were recognizable at end diastole (p < 0.01), 2.5 segments at end systole (p < 0.02). Left heart contrast improves interobserver-variability of end diastolic volume (p < 0.006), end systolic volume (p < 0.004), ejection fraction (p < 0.0002) and regional wall motion assessment (p < 0.03). Side effects did not occur. CONCLUSIONS: The intravenous injection of the investigated phospholipid-based echo contrast agent improves left ventricular endocardial border delineation and reproducibility of left ventricular volumes, ejection fraction and regional wall motion assessment.

Adult↗
PubMed1993

Systolic left ventricular function after reperfusion therapy for acute myocardial infarction. Analysis of determinants of improvement. The TAMI Study Group.

BACKGROUND: Contrast ventriculograms of 542 patients treated with intravenous thrombolytic agents for acute myocardial infarction were examined to define changes in left ventricular ejection fraction and regional wall motion that occur during the first week after reperfusion therapy for acute myocardial infarction and define clinical, acute angiographic and treatment variables related to improvement in global and regional left ventricular function. METHODS AND RESULTS: Intravenous tissue-type plasminogen activator and/or urokinase was administered to 805 patients during acute myocardial infarction. Mean time from symptom onset to thrombolytic therapy was 3 hours (22 patients received therapy within the first hour). Acute and 7-day catheterization were performed. Paired left ventricular ejection fraction and centerline regional wall motion were available in 542 patients (67%). Stepwise, multivariable analysis of clinical, acute angiographic and treatment variables was used to develop two models: One related to improvement in left ventricular ejection fraction, and the second related to improvement in infarct zone regional function. Left ventricular ejection fraction did not change (51.2 +/- 11.1% for acute versus 51.9 +/- 11.0% for 1 week, p = 0.19). Improvement in infarct zone regional function was modest (14%) at 1 week (-2.54 +/- 1.07 standard deviation per chord for acute versus -2.17 +/- 1.24 at 1 week, p < 0.001). Subgroup analysis demonstrated modest improvement in ejection fraction (1.4 +/- 9.5%) and greater improvement in infarct zone function (19%) in patients with successful sustained reperfusion at 1 week. Depressed left ventricular ejection fraction and infarct zone regional wall motion at the acute study were strongly associated with improvement of these parameters at 1 week. Resolution of chest pain before acute catheterization, infarct-related artery flow at acute catheterization, and depressed regional wall motion in the noninfarct zone were associated with improvement in both ejection fraction and regional infarct zone function at 1 week. Notably, the time from the onset of symptoms to initiation of thrombolytic treatment was not related to subsequent improvement in ventricular function. CONCLUSIONS: Dramatic improvement in left ventricular systolic function is not common after thrombolytic therapy for acute myocardial infarction. Improvement in global and regional systolic function is most closely related to acutely depressed ventricular function and successful acute coronary recanalization. Thus, patients with the most myocardium in jeopardy and successful coronary reperfusion demonstrate the greatest improvement in global and infarct zone ventricular function. Overall, the magnitude of this improvement is modest, suggesting that the benefits of coronary reperfusion are not solely related to improvement in systolic left ventricular function.

Aged↗
PubMed1989

Effect of the hemopump left ventricular assist device on regional myocardial perfusion and function. Reduction of ischemia during coronary occlusion.

The Hemopump is a new 7-mm diameter left ventricular assist device that provides as much as 3.5 l/min of nonpulsatile cardiac output after fluoroscopic placement into the left ventricle through a femoral artery cutdown. The purpose of this study was to measure the effects of Hemopump assist on hemodynamics, left ventricular function, and perfusion in the presence and absence of ischemia. Eight dogs were instrumented under pentobarbital anesthesia with left ventricular, left atrial, and aortic catheters, a loose silk ligature around the midleft anterior descending coronary artery, and sonomicrometer crystals in midwall myocardium within the left anterior descending and circumflex perfusion territories. Hemodynamic variables, regional systolic fractional shortening, and myocardial perfusion after left atrial injection of 15-microns radiolabeled microspheres were measured in the presence and absence of Hemopump assist before and after left anterior descending artery occlusion. In the absence of ischemia, Hemopump left ventricular assist resulted in reduced left ventricular end-diastolic pressure while aortic mean pressure was maintained, and there was significant reduction in regional systolic fractional shortening (reflecting systolic unloading) that correlated with an 18% decline in regional myocardial perfusion. During left anterior descending artery occlusion, left ventricular systolic and diastolic pressures were reduced during Hemopump assist while aortic mean pressure was maintained. Perfusion rose in the ischemic territory (from 13.0 +/- 8.7% to 26.2 +/- 19.8% of nonischemic flow, p = 0.045). Reduced fractional shortening was again seen in nonischemic tissue with Hemopump assist during left anterior descending artery occlusion, and this was often correlated with reduced perfusion (r = 0.67).(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1991

Brain-behavior relationships in aphasia studied by positron emission tomography.

Positron emission tomography allows for the study of human brain physiology and chemistry including cerebral blood flow, oxygen or glucose metabolism. We applied PET to study glucose metabolism using aphasia as a model of neurobehavior. The most striking observation was that the extent of cerebral glucose metabolic changes in aphasic patients consistently involve brain regions that are not structurally damaged. The remote metabolic effects can be predicted depending on the location and extent of structural damage. Two observations were made: (1) In our experience, all right-handed aphasic patients with left hemisphere structural lesions have metabolic abnormalities in the left temporoparietal region, and (2) metabolic abnormalities are variably found in undamaged, left prefrontal lobe, basal ganglia, and thalamus. Variations in clinical aphasic syndromes were found to relate to these frontal metabolic changes, suggesting that aspects of the aphasia result from differences in prefrontal function rather than directly from structural damage to perisylvian or deep structures.

Aphasia↗
PubMedDate not supplied

Regional three-dimensional geometry of the normal human left ventricle using cine computed tomography.

The aim of this study is to provide accurate three-dimensional measurements of left ventricular geometrical indices in relation to regional myocardial function. The analysis of the three-dimensional regional geometry and function of left ventricles of ten normal human volunteers is based on three-dimensional reconstructions of the left ventricle from cine computed tomography images, at end diastole and end systole, demonstrating normal left ventricular spatial, geometrical, and functional variability. Regional wall thickness, curvature and surface normals, as well as wall thickening and endocardial wall motion, are calculated and mapped for the entire left ventricle. The circumferential asymmetry of the left ventricle is reflected by the smaller circumferential and meridional curvatures at the septum. Thickening is highest at the anterior and lateral walls. Longitudinally, circumferential curvature increases toward the apex, whereas both wall thickness and wall thickening at end systole are largest at the midventricular level, decreasing toward the apex and base. This study describes the circumferential and apex-to-base variations in regional left ventricular geometric parameters of the normal human left ventricle, using three-dimensional imaging and analysis.

Adult↗
PubMed1999

Use of segmental tissue Doppler velocity to quantitate exercise echocardiography.

BACKGROUND: A quantitative technique is required to reduce the subjectivity and improve the reproducibility of stress echocardiography. Tissue Doppler imaging may offer these benefits, but its feasibility with exercise echocardiography (ExE) is undefined. This study sought the determinants of the exercise tissue Doppler velocity (TDV) response and the feasibility and accuracy of color TDV during ExE. METHODS AND RESULTS: Fifteen volunteers and 85 patients (age 60 +/- 10 years, 19 women) with known or suspected coronary artery disease were studied with standard 2-dimensional (2D) echocardiography and pulsed wave (PW) and color TDV before and after they underwent exercise treadmill testing. After the study PW TDV was measured in 6 basal segments, and off-line software was used to display color TDV data from all myocardial segments. Color TDV was compared with PW TDV in the basal segments at rest and stress with the use of linear regression. Color TDV in mid and basal segments was compared with wall motion on 2D echocardiography. The predictors of the TDV response to exercise were defined in a multiple linear regression. A logistic regression model was used to integrate clinical, exercise, and TDV variables for prediction of abnormal regional left ventricular function. Color and PW correlated well at rest (r = 0.81) and stress (r = 0.84), but PW was greater than color velocities at rest and stress. On the basis of 2D echocardiography, 752 myocardial segments were classified as normal in patients without evidence of coronary disease, 309 were normal in patients with abnormal wall motion in another territory, and 128 showed ischemia or scar. Segmental comparison of velocities assessed by color TDV showed that scar segments had a lower velocity than normal segments at rest and stress (P <.001). Ischemic segments had a lower peak TDV and less increment in velocity than normal segments. Heart rate, functional capacity, and regional dysfunction (scar or ischemia) were independent predictors of TDV at peak exercise. With the use of receiver operating characteristic analysis, the "correction" of TDV by these other variables increased the accuracy of the technique for the detection of regional left ventricular dysfunction. CONCLUSION: Color TDV is feasible during ExE. The correlation found between TDV and wall motion analysis of experienced observers indicates that TDV may be useful as a quantitative tool for interpretation of ExE.

Blood Flow Velocity↗
PubMed2000

Sympathetic reinnervation of sinus node and left ventricle after heart transplantation in humans: regional differences assessed by heart rate variability and positron emission tomography.

BACKGROUND: Orthotopic heart transplantation (HTx) results in complete cardiac denervation. Reestablished partial sympathetic nerve function has been found in patients some years after HTx. However, the atrial and ventricular regional patterns of reinnervation have not been established. METHODS: Two parallel methods were used to evaluate the regional restoration of sympathetic nerves in the myocardium. Patients were investigated with respect to ventricular reinnervation (VI) using positron emission tomography (PET) and the norepinephrine analogue C-11-hydroxyephedrine (HED). Tracer uptake was quantified using dynamic imaging protocols, yielding regional HED retention fraction. A regional value above 7%/minute ( +/- 2.5 SD above the mean value of denervated hearts) was considered evidence of sympathetic reinnervation. Spectral analysis of heart rate variability (HRV) served as a quantitative marker for reinnervation at the sinus node (SI). Spectra of HRV during positive head-up tilt were calculated. The low frequency (LF) power spectral density (0.05 to 0.18 Hz) was evaluated. RESULTS: After HTx (4. 6 +/- 3.9 years; range, 0.2 to 13.6 years), 38 patients (aged 50.9 +/- 7.6 years; range, 37 to 65 years) were investigated by PET imaging and HRV. Twenty-two patients with a mean HED retention of 10. 7 +/- 2.6%/minute were classified as left ventricular reinnervated. Sixteen patients with a mean HED retention of 4.8 +/- 0.8%/minute did not reach the threshold. The time difference after HTx was significant for these 2 groups, 5.3 +/- 3.0 years vs 3.8 +/- 4.7 years ( p < 0.05 ). The LF power spectral density of the ventricular reinnervated patients was 5.9 +/- 8.6 ms(2), and 1.8 +/- 4.4 ms(2) (p <0.005 ) for those not reinnervated. Low frequency showed small values and narrow distribution for the patients not reinnervated, assuming sinus node denervation, and showed extended distribution for the reinnervated, suggesting a heterogeneous reinnervation pattern. CONCLUSIONS: Two non-invasive parallel methods were used to investigate regional reestablishment of cardiac nerves in the myocardium in HTx patients. Left VI assessed by PET imaging and SI by HRV was congruent in 60% of HTx patients. Lack of SI paralleled absence of VI. Our results suggest that partial VI occurs prior to SI.

Adult↗
PubMed1992

Quantitative analysis of regional wall thickening by transesophageal echocardiography.

To develop a method for quantitative analysis of regional left ventricular function from transesophageal two-dimensional echocardiograms, we conducted studies 10 and 20 minutes after induction of anesthesia in 16 patients with normal hearts who were undergoing minor orthopedic operations. Wall thickening was measured with the centerwall method along 100 chords drawn perpendicular to a line constructed around the center of the ventricular wall, midway between the endocardial and epicardial contours. Thickening, either normalized by the length of the end-diastolic perimeter or expressed as a percentage of the end-diastolic wall thickness at each chord, was compared with measurements of endocardial motion. Wall motion was relatively diminished in the anteroseptal region and enhanced on the contralateral wall, but wall thickening was homogeneous throughout the contour. Normalized wall thickening was significantly less variable (standard deviation/mean, 0.47 +/- 0.13) in the normal population than were either percent wall thickening (0.53 +/- 0.012) or wall motion (0.51 +/- 0.09) (p less than 0.005 for both comparisons). There was no significant change in regional or global function between 10 minutes and 20 minutes after the induction of anesthesia. In summary, normalized wall thickening as a parameter of regional left ventricular function is more homogeneous and less variable in subjects with normal hearts than is endocardial motion because wall thickening measurements are not subject to cardiac translocation artifacts. This low variability suggests that normalized wall thickening measured by the centerwall method may prove particularly useful for intraoperative and postoperative monitoring of regional left ventricular function by transesophageal echocardiography in patients undergoing both cardiac and noncardiac surgical procedures.

Adult↗
PubMed1984

Accurate estimates of absolute left ventricular volumes from equilibrium radionuclide angiographic count data using a simple geometric attenuation correction.

To simplify and clarify the methods of obtaining attenuation-corrected equilibrium radionuclide angiographic estimates of absolute left ventricular volumes, 27 patients who also had biplane contrast cineangiography were evaluated. Background-corrected left ventricular end-diastolic and end-systolic counts were obtained by semiautomated variable and hand-drawn regions of interest and were normalized to cardiac cycles processed, frame rate and blood sample counts. Blood sample counts were acquired on (d degree) and at a distance (d') from the collimator. A simple geometric attenuation correction was performed to obtain absolute left ventricular volume estimates. Using blood sample counts obtained at d degree or d', the attentuation-corrected radionuclide left ventricular end-diastolic volume estimates using both region of interest selection methods correlated with the cineangiographic end-diastolic volumes (r = 0.95 to 0.96). However, both mean radionuclide semiautomated variable left ventricular end-diastolic volumes (179 +/- 100 [+/- 1 standard deviation] and 185 +/- 102 ml, p less than 0.001) were smaller than the average cineangiographic end-diastolic volume (217 +/- 102 ml), and both mean hand-drawn left ventricular end-diastolic volumes (212 +/- 104 and 220 +/- 106 ml) did not differ from the average cineangiographic end-diastolic volume. Using the blood sample counts obtained at d degree or d', the attenuation-corrected radionuclide left ventricular end-systolic volume estimates using both region of interest selection methods correlated with the cineangiographic end-systolic volumes (r = 0.96 to 0.98). Also, using blood sample counts at d degree, the mean radionuclide semiautomated variable left ventricular end-systolic volume (116 +/- 98 ml, p less than 0.05) was less than the average cineangiographic end-systolic volume (128 +/- 98 ml), and the other radionuclide end-systolic volumes did not differ from the average cineangiographic end-systolic volume. Therefore, it is concluded that: 1) a simple geometric attenuation-correction of radionuclide left ventricular end-diastolic and end-systolic count data provides accurate estimates of biplane cineangiographic end-diastolic and end-systolic volumes; and 2) the hand-drawn region of interest selection method, unlike the semiautomated variable method that underestimates end-diastolic and end-systolic volumes, provides more accurate estimates of biplane cineangiographic left ventricular volumes irrespective of the distance blood sample counts are acquired from the collimator.

Adult↗
PubMed2000

Mitochondrial DNA variation, phylogeography and population structure of the Asian elephant.

We report the first genetic analysis of free-ranging Asian elephants (Elephas maximus). We sampled 118 elephants from Sri Lanka, Bhutan/North India, and Laos/Vietnam by extracting DNA from dung, PCR amplifying and sequencing 630 nucleotides of mitochondrial DNA, including part of the variable left domain of the control region. Comparison with African elephant (Loxodonta africana) sequences indicated a relatively slow molecular clock in the Proboscidea with a sequence divergence of approximately 1%/Myr. Genetic diversity within Asian elephants was low, suggesting a small long-term effective population size. Seventeen haplotypes were identified within Asian elephants, which clustered into two well-differentiated assemblages with an estimated Pliocene divergence of 2.5-3.5 million years ago. The two assemblages showed incomplete geographical partitioning, suggesting allopatric divergence and secondary admixture. On the mainland, little genetic differentiation was observed between elephant populations of Bhutan and India or Laos and Vietnam. A significant difference in haplotype frequencies but relatively weak subdivision was observed between the regions Bhutan-India and Laos-Vietnam. Significant genetic differentiation was observed between the mainland and Sri Lanka, and between northern, mid-latitude and southern regions in Sri Lanka.

Animals↗