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Apical Segments (apical + segment)

Distribution by Scientific Domains

Medical Sciences	66%
Life Sciences	33%

Selected Abstracts

Role of Parasternal Data Acquisition During Contrast Enhanced Real-Time Three-Dimensional Echocardiography

ECHOCARDIOGRAPHY, Issue 10 2007
Attila Nemes M.D., Ph.D.
Background: Recent technical developments have resulted in high-resolution real time three-dimensional echocardiography (RT3DE). The purpose of this study was to investigate the beneficial role of parasternal-acquired images in addition to apical-acquired images during contrast stress RT3DE. Methods: The study comprised 30 consecutive patients (52 ± 11 years, 18 males) with chest pain referred for routine stress testing. The contrast RT3DE images were acquired from the apical and parasternal window with a Sonos 7500 echo system attached to a X4 matrix array transducer. Results: From the apical and parasternal acquisition, 464 segments (91%) and 267 segments (52%) could be analyzed, respectively (P < 0.001). From the apical window, more basal segments were not analyzable (22 of 180, 12% vs. 24 of 330, 7%; P = 0.06). From the parasternal window, more apical segments were not analyzable (117 of 150, 78% vs. 126 of 360, 35%; P < 0.01). The mean image quality index of the 464 analyzable segments from the apical-acquired images was 2.43. Fourteen of 180 basal segments (8%), 12 of 180 midventricular segments (7%) and 2 of 150 apical segment (1%) were only available with parasternal data acquisition. In addition to these 28 segments, 79 segments (15%) already visualized from the apical window improved in quality. The overall mean image quality index, now assessed from 492 (96%) of all segments, using both the apical and parasternal acquired data, improved to 2.74 (P < 0.05). Conclusions: Addition of parasternal to apical acquisition of contrast RT3DE data can decrease the number of nonvisualized segments and improve mean image quality. [source]

Micro-CT evaluation of residual material in canals filled with Activ GP or GuttaFlow following removal with NiTi instruments

INTERNATIONAL ENDODONTIC JOURNAL, Issue 3 2010
M. J. Roggendorf
Roggendorf MJ, Legner M, Ebert J, Fillery E, Frankenberger R, Friedman S. Micro-CT evaluation of residual material in canals filled with Activ GP or GuttaFlow following removal with NiTi instruments. International Endodontic Journal, 43, 200,209, 2010. Abstract Aim, To assess the efficacy of removing Activ GP or GuttaFlow from canals using NiTi instruments. Methodology, Root canals in 55 extracted pre-molars were prepared to apical size 40, 0.04 taper. The teeth were imaged with micro-CT, and 30 teeth selected that had consistent apical size and taper of the shaped canals. They were randomly assigned to root filling with either the glass-ionomer-based ActivGP system (n = 15) or the polyvinylsiloxane-based GuttaFlow system (n = 15). After 2 weeks, canals were retreated stepwise with size 40,50 EndoSequence 0.04 taper instruments. Micro-CT scans (8 ,m) were taken after use of each instrument to detect root filling residue in the coronal, middle and apical segment, and the retreatment time recorded. Residue, expressed as percentage of canal surface area, was compared between groups with t -tests, and within groups with repeated measures anova and Bonferroni-adjusted pairwise comparisons. Retreatment time was analysed with one-way anova. Results, The percentage of sealer residue-coated canal surface was consistently highest (P < 0.001) in the apical third of canals, and it did not differ significantly between the two root filling groups. Stepwise enlargement from size 40 to 50 significantly decreased the amount of sealer residue in both groups (P < 0.001). Retreatment time did not differ significantly between groups. Conclusions, Both root fillings with ActivGP and GuttaFlow were removed with nickel-titanium rotary instruments. Enlargement of canals up to two sizes beyond the pre-retreatment size was necessary to minimize the amount of sealer remaining. [source]

Sperm morphology of the eurasian beaver, Castor fiber: An example of a species of rodent with highly derived and pleiomorphic sperm populations

JOURNAL OF MORPHOLOGY, Issue 8 2007
Joanna B. Bierla
Abstract The structural organization of the spermatozoon from the Eurasian beaver, Castor fiber (Family: Castoridae), was determined and compared to that of other sciuromorph rodents. The beaver spermatozoon has a head, which is variable in form but usually paddle-shaped, with a small nucleus and very large acrosome, and a tail that is relatively short compared to that of most other rodents. Transmission electron microscopy indicates that in most testicular spermatozoa the acrosome projects apically, although in a few it becomes partly flexed. During the final stages of maturation, however, the acrosome becomes highly folded so that the apical segment comes to lie alongside part of the acrosome that occurs lateral to the nucleus, with, in some cases, fusion taking place between the outer acrosomal membranes. The sperm nucleus is wedge-shaped, being broader basally and narrowing apically with an occasional large nuclear vacuole occurring. This spermatozoon structure is markedly different from that found in the other species of Geomyoidea, which is the sister group of the Castoridae. The findings thus emphasize the highly divergent nature of the beaver spermatozoon and demonstrate that, within the proposed Infraorder Castorimorpha, very large differences in sperm structure have evolved. J. Morphol., 2007. © 2007 Wiley-Liss, Inc. [source]

The evolution of arthropod limbs

BIOLOGICAL REVIEWS, Issue 2 2004
Geoff A. Boxshall
ABSTRACT Limb morphology across the arthropods is reviewed using external morphological and internal anatomical data from both recent and fossil arthropods. Evolutionary trends in limb structure are identified primarily by reference to the more rigorous of the many existing phylogenetic schemes, but no major new phylogenetic inferences are presented. Tagmosis patterns are not considered, although the origins and patterns of heteronomy within the postantennulary limb series are analysed. The phenomenon of annulation is examined and two basic types of annuli are recognised: terminal and intercalary. The annulation of the apical segment of a limb results in the formation of terminal flagella, and is typical of primarily sensory appendages such as insect and malacostracan antennules and maxillary palps of some hexapods. Intercalary annulation, arising by subdivision of existing subterminal segments, is common, particularly in the tarsal region of arthropodan walking limbs. Differentiating between segments and annuli is discussed and is recognised as a limiting factor in the interpretation of fossils, which usually lack information on intrinsic musculature, and in the construction of groundplans. Rare examples of secondary segmentation, where the criteria for distinguishing between segments and annuli fail, are also highlighted. The basic crown-group arthropodan limb is identified as tripartite, comprising protopodite, telopodite and exopodite, and the basic segmentation patterns of each of these parts are hypothesised. Possible criteria are discussed that can be used for establishing the boundary between protopodite and telopodite in limbs that are uniramous through loss of the exopodite. The subdivision of the protopodite, which is typical of the postantennulary limbs of mandibulates, is examined. The difficulties resulting from the partial or complete failure of expression of articulations within the mandibulate protopodite and subsequent incorporation of partial proto-podal segments into the body wall, are also discussed. The development and homology between the various exites, including gills, on the postantennulary limbs of arthropods are considered in some detail, and the question of the possible homology between crustacean gills and insect wings is critically addressed. The hypothesis that there are only two basic limb types in arthropods, antennules and postantennulary limbs, is proposed and its apparent contradiction by the transformation of antennules into walking limbs by homeotic mutation is discussed with respect to the appropriate level of serial homology between these limbs. [source]

Segmental Contribution to Left Ventricular Systolic Function at Rest and Stress: A Quantitative Real Time Three-Dimensional Echocardiographic Study

ECHOCARDIOGRAPHY, Issue 2 2010
F.A.S.E., Smadar Kort M.D.
Objective: To assess the relative contribution of each myocardial segment to global systolic function during stress using real time three-dimensional echocardiography (RT3DE). Background: During stress, global augmentation in contractility results in an increased stroke volume. The relative contribution of each myocardial segment to these volumetric changes is unknown. Methods: Full volume was acquired using RT3DE at rest and following peak exercise in 22 patients who had no ischemia and no systolic dyssynchrony on two-dimensional (2D) stress echocardiography. The following were calculated at rest and peak stress: end-diastolic volume (EDV), end-systolic volume (ESV), stroke volume (SV), ejection fraction (EF), relative SV, and relative EF. Results: With stress, an increase in global EDV from 90.8 to 101.1 ml (P < 0.001), SV from 59 to 78.4 ml (P = 0.01), and EF from 65.6 to 78.4% (P = 0.001) was observed. ESV decreased from 31.8 to 22.7 ml (P < 0.001). Segmental analysis revealed significantly higher SV, relative SV, and relative EF for the basal anterior, basal anterolateral, and basal inferolateral segments compared with the apical septum and apical inferior segments at both rest and stress (P < 0.001). The SV, relative SV, and relative EF increased significantly from apex to mid to base at both rest and stress (P < 0.001). Conclusions: The relative volumetric contribution of each myocardial segment to global left ventricular systolic function at rest and stress is not uniform. The basal segments contribute more than the mid and apical segments. Specifically, the basal anterior, basal anterolateral, and basal inferolateral segments contribute the most to augmentation of left ventricular systolic function with exercise. (ECHOCARDIOGRAPHY 2010;27:167-173) [source]

Role of Parasternal Data Acquisition During Contrast Enhanced Real-Time Three-Dimensional Echocardiography

Effect of Angular Error on Tissue Doppler Velocities and Strain

ECHOCARDIOGRAPHY, Issue 7 2003
Camilla Storaa M.S.
One of the major criticisms of ultrasound Doppler is its angle dependency, that is its ability to measure velocity components directly to or from the transducer only. The present article aims to investigate the impact of this angular error in a clinical setting. Apical two- and four-chamber views were recorded in 43 individuals, and the myocardium was marked by hand in each image. We assume that the main direction of the myocardial velocities is longitudinal and correct for the angular error by backprojecting measured velocities onto the longitudinal direction drawn. Strain was calculated from both corrected and uncorrected velocities in 12 segments for each individual. The results indicate that the difference between strain values calculated from corrected and uncorrected velocities is insignificant in 5 segments and within a decimal range in 11 segments. The biggest difference between measured and corrected strain values was found in the apical segments. Strain is also found to be more robust against angular error than velocities because the difference between corrected and uncorrected values is smaller for strain. Considering that there are multiple sources of noise in ultrasound Doppler measurements, the authors conclude that the angular error has so little impact on longitudinal strain that correction for this error can safely be omitted. (ECHOCARDIOGRAPHY, Volume 20, October 2003) [source]

Quantitative Assessment of Regional Right Ventricular Myocardial Velocities in Awake Dogs by Doppler Tissue Imaging: Repeatability, Reproducibility, Effect of Body Weight and Breed, and Comparison with Left Ventricular Myocardial Velocities

JOURNAL OF VETERINARY INTERNAL MEDICINE, Issue 6 2005
Valérie Chetboul
Right ventricular myocardial (RVM) motion is poorly documented. The objective of this study was to determine the variability of RVM velocities by tissue Doppler imaging (TDI) in healthy dogs (study 1), to analyze RVM motion in a large healthy canine population (study 2), and to compare the results with those obtained for the left ventricular free wall. Six healthy Beagle Dogs were monitored in study 1, and 64 healthy dogs of 14 different breeds were monitored in study 2. Velocities were recorded in 2 segments (basal and apical) of the right and left myocardial walls. In study 1, 36 TDI examinations were performed for 4 days, whereas a single TDI examination was performed on each dog in study 2. All velocity profiles included 1 positive systolic wave and 2 negative diastolic waves. The lowest intraday and interday coefficient of variation values of the right TDI variables were observed at the base (3.5,16.1%). The variability of the right apical velocities was much higher, with most coefficient of variation values >15%. RVM velocities were higher in the basal than in the apical segments (P < .001) and were higher than the left velocities of the corresponding segment (P < .01). Body weight and breed had an effect on only a few right and left TDI variables. TDI provides a repeatable and reproducible method for evaluating basal RV function in the dog. These data also demonstrate the heterogeneity of the myocardial velocities between the left and the right ventricles and between the base and the apex. [source]

Apical callus formation and plant regeneration controlled by plant growth regulators on axenic culture of the red alga Gracilariopsis tenuifrons (Gracilariales, Rhodophyta)

PHYCOLOGICAL RESEARCH, Issue 3 2000
Nair S. Yokoya
SUMMARY Axenic cultures of Gracilariopsis tenuifrons (Bird et Oliveira) Fredericq et Hommersand (Gracilariales, Rhodophyta) were established in ASP12-NTA solid medium (0.4% agar and 1.0% sucrose) supplemented with plant growth regulators to evaluate the effects on apical callus formation and plant regeneration. Indole-3-acetic acid (IAA), 2,4-dichlorophenoxyacetic acid (2,4-D) and 6-benzylaminopurine (BA) were added individually or in combinations (IAA : BA) over a range of concentrations from 0.5 to 5 mg L,1. Growth of apical and intercalary segments was stimulated by high concentrations of 2,4-D (5 mg L,1) and a high IAA to BA ratio (IAA : BA = 5:1 mg L,1) respectively. Apical calluses were originated from divisions of apical and cortical cells located at apical regions of thallus segments and lateral branches. Low concentration of IAA (0.5 mg L,1) or a high IAA to BA ratio (IAA : BA = 5:1 mg L,1) were the optimal treatments for inducing apical callus formation in apical segments, while high concentration of IAA (5 mg L,1) stimulated the highest callus induction rate in intercalary segments. Conversely, equal parts IAA and BA (IAA : BA = 1:1 mg L,1) and low concentration of 2,4-D (0.5 mg L,1) stimulated growth of apical calluses from apical and intercalary segments, respectively. Two processes of regeneration were observed: direct regeneration (upright axis originated from cells of proximal region of intercalary segments) and indirect regeneration (adventitious plantlet originated from cells of apical calluses). Direct regeneration was promoted significantly by treatment with a low IAA to BA ratio (IAA : BA= 1:5 mg L,1), and treatments with IAA (0.5 mgL,1) or 2,4-D (0.5 or 5 mg L,1) significantly stimulated the elongation of upright axis. Plant growth regulators are essential to inducing indirect regeneration, and a high concentration of IAA (5 mg L,1) and BA (5 mg L,1) were the optimal treatments for inducing the regeneration of plantlets from apical calluses in apical and intercalary segments, respectively. Regenerating plantlets grew into plants morphologically similar to those formed from germinating spores, and became fertile after 6 weeks. The results suggest that auxins and cytokinins are involved in developmental regulatory processes in G. tenuifrons. The regeneration process from calluses in species of Gracilariales was observed for the first time in the present study. The culture system described for G. tenuifrons could be useful for micropropagation and for biotechnological applications in agarophytic algae. [source]