scholarly journals Heart development in the lizards (Varanidae) with the greatest extent of ventricular septation

2019 ◽  
Author(s):  
Jermo Hanemaaijer ◽  
Martina Gregorovicova ◽  
Jan M. Nielsen ◽  
Antoon FM Moorman ◽  
Tobias Wang ◽  
...  
Keyword(s):  
Heart Development ◽  
Ventricular Septum ◽  
Systemic Blood ◽  
Septum Formation ◽  
Cardiac Ventricle ◽  
Vertical Septum ◽  
Blood Pressures ◽  
Left And Right ◽  
Monitor Lizards ◽  
The Right

AbstractAmong lizards, only monitor lizards (Varanidae) have a functionally divided cardiac ventricle. This enables them to sustain higher systemic blood pressures and higher metabolic rates than other reptiles of similar size. The division results from the concerted action of three partial septa, which may have homology to the full ventricular septum of mammals and archosaurs. Homology, however has only been inferred from anatomical comparisons of hearts of adult monitors whereas gene expression during heart development has not been studied. We show in developing monitors that the partial septa that separate the left and right ventricle, the ‘muscular ridge’ and ‘bulbuslamelle’, express the evolutionary conserved transcription factors Tbx5, Irx1 and Irx2, orthologues of which mark the full ventricular septum. Compaction of embryonic trabeculae contributes to the formation of these septa. The septa are positioned, however, to the right of the atrioventricular junction and they do not partake in the separation of incoming atrial blood streams. Instead, the ‘vertical septum’ within the left ventricle separates the atrial blood streams. It expresses Tbx3 and Tbx5, which orchestrate the formation of the electrical conduction axis of the full ventricular septum. These patterns of expression are more pronounced in monitors than in other lizards, and are associated with a deep electrical activation near the vertical septum, contrasting the primitive base-to-apex activation of other lizards. We conclude that current concepts of ventricular septum formation apply well to the monitor septa and that there is evolutionary conservation of ventricular septum formation among amniote vertebrates.

scholarly journals THE PHYSIOLOGY OF THE ALLIGATOR HEART: LEFT AORTIC FLOW PATTERNS AND RIGHT-TO-LEFT SHUNTS

1993 ◽  
Vol 176 (1) ◽  
pp. 247-270 ◽  
Author(s):  
D. R. Jones ◽  
G. Shelton
Keyword(s):  
Cardiac Output ◽  
Flow Pattern ◽  
Pulmonary Arteries ◽  
Systemic Blood Pressure ◽  
Aortic Flow ◽  
Pharmacological Intervention ◽  
Systemic Blood ◽  
Blood Pressures ◽  
Alkaline Tide ◽  
The Right

Blood pressures have been recorded in the heart along with pressures and flow in the aortic arches of anaesthetized and awake alligators. Systemic blood pressures were significantly lower [5.22+/−0.57 kPa (N=3) versus 9.85+/−0.46 kPa (N=5)] and cardiac outputs higher [51.6+/−3.5 ml min-1 kg-1 (N=3) versus 25.5+/−8.2 ml min-1 kg-1 (N=5)] in awake compared with anaesthetized animals. Using pharmacological interventions, two types of right-to-left shunt could be induced in all alligators. In one, established after acetylcholine (ACh) injection into the right side of the circulation, left aortic flow was an anterograde monophasic pulse which occurred when pulmonary pressure exceeded systemic blood pressure. Hence, this left aortic flow pattern could also be induced by mechanical occlusion of both pulmonary arteries. About one-quarter of cardiac output could bypass the lungs during this shunt. However, this left aortic flow pattern was never seen under any conditions other than pharmacological intervention. In the other type of shunt, induced pharmacologically by ACh injection into the left side of the circulation, left aortic flow was biphasic with a period of backflow, initiated during systole, being progressively shortened by the onset of forward flow from the right ventricle. Establishment of this type of shunt depended on the magnitude of both the systemic pressure and the pressure generated by right ventricular contraction after closure of the pulmonary outflow tract. The amount of blood bypassing the lungs during this shunt was small (13.7+/−5 % of cardiac output) but, at maximum, could be almost 25 % of cardiac output. This shunt occurred naturally in resting animals and could be maintained for substantial periods (13.2 min). The present observations confirm those made previously on anaesthetized alligators and extend previous work by showing two potential types of shunt. Finally, we suggest that right-to-left blood shunting in crocodilians may be related to the ‘alkaline tide’ that occurs after feeding, so the unique design of the central cardiovascular system in crocodilians could relate to both gastrointestinal and cardiorespiratory physiology.

scholarly journals The Physiology of the Alligator Heart: the Cardiac Cycle

1991 ◽  
Vol 158 (1) ◽  
pp. 539-564 ◽  
Author(s):  
G. SHELTON ◽  
D. R. JONES
Keyword(s):  
Right Ventricle ◽  
Cardiac Cycle ◽  
Pulmonary Arteries ◽  
Outflow Tract ◽  
Pressure Gradients ◽  
Aortic Valves ◽  
Systemic Blood ◽  
Second Stage ◽  
Blood Pressures ◽  
The Right

Pressure recordings from the heart and major arteries of the alligator show that a conventional relationship exists between the left ventricle and the right aorta. Pressure gradients from ventricle to aorta during systole are very small. Right aortic blood flow rises rapidly to a single peak and then falls more gradually until aortic valve closure. The right ventricle is connected both to the pulmonary arteries and to the left aorta. Right ventricular pressures show that systole is a two-stage process. Initially, blood leaves to the low-resistance lung circuit, though appreciable pressure gradients exist across the pulmonary outflow tract. Active contraction of the pulmonary outflow tract stops pulmonary ejection and a second-stage pressure rise is seen in the right ventricle. When systemic blood pressures are high, this second-stage pressure does not reach the levels recorded in the left aorta, and the left aortic valves remain closed so that lung and body circuits are functionally separate. An alternation of flow is found in the left aorta under these conditions, with reversed flow during systole and forward flow during diastole. Flow rates are extremely low, compared with those in the right aorta or pulmonary arteries, and the foramen of Panizza has very little significance in the cardiac cycle. If the systemic blood pressures are low, the second stage of systole in the right ventricle gives rise to pressures that are higher than those in the left aorta, the left aortic valves open and blood is ejected to the systemic circulation, giving a right-to-left shunt. This can occur with no changes in pulmonary pressures or flows. Left aortic flow is not dependent on increased constriction of the pulmonary outflow tract, which continues to function as an on-off active valve. Constriction within the lung vasculature may, on some occasions, be significant in establishing left aortic flow, but it is clear from the present work that low systemic blood pressure is a factor of crucial importance.

Intraventricular blood pressures in the chicken

1960 ◽  
Vol 198 (1) ◽  
pp. 153-154 ◽  
Author(s):  
H. E. Bredeck
Keyword(s):  
Blood Pressure ◽  
Heart Rate ◽  
Systolic Pressure ◽  
Left Ventricular Pressure ◽  
Left Ventricular ◽  
The Other ◽  
Blood Pressures ◽  
Left And Right ◽  
The Right ◽  
Made In

Direct heart punctures were made in two groups of unanesthetized chickens to determine the left and right intraventricular blood pressures. One group was composed of nonlaying birds 28–30 weeks old and the other of laying hens 65–67 weeks of age. Heart rates and the respiratory influence on pressure were also measured. Average pressures obtained were 144/0 and 21/ - 1 mm Hg for the left and right ventricle, respectively. Respiratory efforts caused a mean fluctuation in systolic pressure of approximately 8 mm Hg in the left ventricle and 4 mm Hg in the right. With the exception of the right ventricular diastolic blood pressure, there were no significant pressure or pulse rate differences between the two groups. The heart rate and left ventricular pressure were found to be significantly correlated ( P < .01) in both groups of birds.

Comparison of the efficiency of the indexes of Pont and Korkhause with Kernott technique in patients with narrowing of maxilla

2020 ◽  
Vol 20 (3) ◽  
pp. 199-203
Author(s):  
O. I. Admakin ◽  
I. A. Solop ◽  
A. D. Oksentyuk
Keyword(s):  
Dental Treatment ◽  
Standard Analysis ◽  
Clinical Hospital ◽  
Control Models ◽  
Diagnostic Models ◽  
Left And Right ◽  
The Asymmetry ◽  
The Right ◽  
The University ◽  
Medical University

Relevance. The narrowing of the maxilla is one of the most common pathologies in orthodontics. Recent studies show that the narrowing is always asymmetric which is connected to the rotation of the maxilla. To choose the treatment correctly one need a calculation that reveals the asymmetry, which is impossible with using standard indexes.Purpose – to compare efficiency of indexes of Pont and Korkhause with the Kernott's method in patients with narrowing of the maxilla.Materials and methods. The study involved 35 children aged from 8 to 12 years old undergoing dental treatment in the University Children's Clinical Hospital of the First Moscow State Medical University with no comorbidities. For every patient a gypsum model was prepared and after that to carry out the biometrical calculation. In this study two indexes were used: Pont's index and Korkhause's; using this standard analysis the narrowing of the maxilla was revealed. After using Pont's Index and Korkhaus analysis all the models were calculated by the method of Kernott with Kernott's dynamic pentagon.Results. As a result of the analysis of the control diagnostic models a narrowing of the maxilla in 69% of cases (n = 24) was revealed in all cases, the deviation of the size of the dentition was asymmetric. Thus, 65% of the surveyed models showed a narrowing on the right. This narrowing was of a different severity and averaged 15 control models.Conclusions. This shows that for the biometrics of diagnostic models it is necessary to use methods that allow to estimate the width of the dentition rows on the left and on the right separately. To correct the asymmetric narrowing of the dentition, it is preferable to use non-classical expanding devices that act equally on the left and right sides separetly.

scholarly journals Transcriptomic uniqueness and commonality of the ion channels and transporters in the four heart chambers

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Sanda Iacobas ◽  
Bogdan Amuzescu ◽  
Dumitru A. Iacobas
Keyword(s):  
Ion Channels ◽  
Cycle Phase ◽  
Functional Roles ◽  
Expression Control ◽  
Gene Expression Control ◽  
Left And Right ◽  
The Right ◽  
Phase Out ◽  
Right Atria ◽  
Agilent Microarrays

AbstractMyocardium transcriptomes of left and right atria and ventricles from four adult male C57Bl/6j mice were profiled with Agilent microarrays to identify the differences responsible for the distinct functional roles of the four heart chambers. Female mice were not investigated owing to their transcriptome dependence on the estrous cycle phase. Out of the quantified 16,886 unigenes, 15.76% on the left side and 16.5% on the right side exhibited differential expression between the atrium and the ventricle, while 5.8% of genes were differently expressed between the two atria and only 1.2% between the two ventricles. The study revealed also chamber differences in gene expression control and coordination. We analyzed ion channels and transporters, and genes within the cardiac muscle contraction, oxidative phosphorylation, glycolysis/gluconeogenesis, calcium and adrenergic signaling pathways. Interestingly, while expression of Ank2 oscillates in phase with all 27 quantified binding partners in the left ventricle, the percentage of in-phase oscillating partners of Ank2 is 15% and 37% in the left and right atria and 74% in the right ventricle. The analysis indicated high interventricular synchrony of the ion channels expressions and the substantially lower synchrony between the two atria and between the atrium and the ventricle from the same side.

The role of visual experience for spatial numerical associations

2012 ◽  
Vol 25 (0) ◽  
pp. 222 ◽  
Author(s):  
Michael J. Proulx ◽  
Achille Pasqualotto ◽  
Shuichiro Taya
Keyword(s):  
Visual Experience ◽  
Opposite Effect ◽  
Random Number Generation ◽  
Number Line ◽  
Mental Number Line ◽  
Generation Task ◽  
Congenitally Blind ◽  
Left And Right ◽  
The Right

The topographic representation of space interacts with the mental representation of number. Evidence for such number–space relations have been reported in both synaesthetic and non-synaesthetic participants. Thus far most studies have only examined related effects in sighted participants. For example, the mental number line increases in magnitude from left to right in sighted individuals (Loetscher et al., 2008, Curr. Biol.). What is unclear is whether this association arises from innate mechanisms or requires visual experience early in life to develop in this way. Here we investigated the role of visual experience for the left to right spatial numerical association using a random number generation task in congenitally blind, late blind, and blindfolded sighted participants. Participants orally generated numbers randomly whilst turning their head to the left and right. Sighted participants generated smaller numbers when they turned their head to the left than to the right, consistent with past results. In contrast, congenitally blind participants generated smaller numbers when they turned their head to the right than to the left, exhibiting the opposite effect. The results of the late blind participants showed an intermediate profile between that of the sighted and congenitally blind participants. Visual experience early in life is therefore necessary for the development of the spatial numerical association of the mental number line.

scholarly journals Surface Evolution During Semiconductor Processing

VLSI Design ◽  
1998 ◽  
Vol 6 (1-4) ◽  
pp. 379-384 ◽  
Author(s):  
Ganesh Rajagopalan ◽  
Vadali Mahadev ◽  
Timothy S. Cale
Keyword(s):  
Riemann Problem ◽  
Surface Profile ◽  
Numerical Implementation ◽  
Jump Conditions ◽  
Semiconductor Processing ◽  
Explicit Integration ◽  
Surface Evolution ◽  
Left And Right ◽  
The Right ◽  
Surface Angle

We discuss our approach to using the Riemann problem to compute surface profile evolution during the simulation of deposition, etch and reflow processes. Each pair of segments which represents the surface is processed sequentially. For cases in which both segments are the same material, the Riemann problem is solved. For cases in which the two segments are different materials, two Riemann problems are solved. The material boundary is treated as the right segment for the left material and as the left segment for the right material. The critical equations for the analyses are the characteristics of the Riemann problem and the ‘jump conditions’ which represent continuity of the surface. Examples are presented to demonstrate selected situations. One limitation of the approach is that the velocity of the surface is not known as a function of the surface angle. Rather, it is known for the angles of the left and right segments. The rate as a function of angle must be assumed for the explicit integration procedure used. Numerical implementation is briefly discussed.

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