Background, Aims and Objectives:
Zebrafish has derived the ability of heart regeneration upon the damage in cardiac muscle. Previous studies have identified cardiomyocytes as the major progenitor cells to undergo cell proliferation in order for heart muscles to regenerate. Epicardial cells that reside in the outer layer of cardiac chambers have also shown to accumulate at the site of would after injuries, which indicates its role in supporting the growth of myocardium.
The participation of epicardial cells in heart regeneration is signaled by the production of retinoic acid (RA), which plays an essential role in the normal cardiac development. Thus, the enzyme that is responsible for RA synthesis, raldh2, is suggested as a potential factor of heart regeneration.
Kikuchi et al. aimed to identify the sources for RA generation, examine heart regeneration on the basis of the function of RA synthesis and its signaling by endocardium in response to injuries. Authors have hypothesized that the endocardium as another source for cardiomyocyte proliferation to support cardiac regeneration.
The opening of the article have referred to the major findings in the field of heart regeneration, which showed the implication of epicardium in promoting cardiac muscle regeneration. Adequate information is provided in relation to the stimulation of RA synthesis. However, the information of RA signaling during normal heart development should be included. Although the aim of the study has been clearly defined, but the hypothesis has not been stated clearly in the introduction. Additionally, authors have also presented the outcomes of the study in the introduction section of the article, whereas the major findings of the study would be better express...
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...feration and the presence of RA during heart regeneration is regulated via the RARs. Overall, the major findings of this study have provided insight of the critical role of RA synthesis in the endocardium and epicardium in stimulating the injury response in order for cardiac regeneration to occur.
Authors have correctly made interpretations based on the outcome of each approaches. Though the mechanism of endocardial regenerative response was uncovered, reasonable predictions in relation to the change in permeability of endocardial cells leading to raldh2 induction have been made. In addition, the authors have also related the results to previous studies in order to back up and supplement the observations found associated with heart regeneration. As a result, a broader knowledge of cardiac regeneration in response to injuries in nonmammalian animals was derived.
Retrieved on March 2014 from world wide web at http://www.webmd.com/heart-disease/guide/heart-disease-heart-attacks Wolf, Zane Robinson & Hughes, Ronda G (n.d.). Error Reporting and Disclosure. Retrieved on March 2014 from world wide web at http://www.ncbi.nlm.nih.gov/books/NBK2652
Throughout the heart, Cardiac Muscle cells are connected together to form a large network from one end to the other. These cells form a shape such that each individual cell always remains in-contact with 3 others cells at all times.
Nitric oxide is a gaseous, diatomic molecule that plays an important role as a mediator of cardiac function, working largely as a vasodilator in the cardiovascular system. Nitric oxide is synthesized by a family of enzymes known as nitric oxide synthases (...
The development of the artificial heart began in the early 1950’s. The initial prototype, developed in 1970’s by the artificial developmental staff at the University of Utah, allowed 50 hours of sustained life in a sheep. Although this was called a success, the implantation of the artificial heart left the sheep in a weakened state. It wasn’t until late 1970’s and the early 1980’s where the improvement of the artificial heart actually received attention as a possible alternative to a heart transplant. The remodeled product of the early 1970’s did more than just the 50 hours of sustained life; it enabled the cow to live longer and to live a relatively normal life, with the exception of a machine attached to the animal.
The science and history of the heart can be traced back as far as the fourth century B.C. Greek philosopher, Aristotle, declared the heart to be the most vital organ in the body based on observations of chick embryos. In the second century A.D, similar ideas were later reestablished in a piece written by Galen called On the Usefulness of the Parts of the Body. Galen’s thesis was that the heart was the source of the body’s essential heat and most closely related to the soul. Galen made careful observations of the physical properties of the heart as well. He said “The heart is a hard flesh, not easily injured. In hardness, tension, in general strength, and resistance to injury, the fibers of the heart far surpasses all others, for no other instrument performs such continues, hard work as the heart”(Galen, Volume 1).
Since its publication in 1925, The Great Gatsby has remained a spot-on representation of a time in American history in which the people believed anything was possible. Gatsby is the definition of this idea. The underlying cause of everything in this novel is his--and in essence everyone’s idea. This idea is the ubiquitous notion of the American Dream. And Fitzgerald does not only write about the American Dream, but about its corruption as well. This following quote truly epitomizes what the American Dream had become in the eyes of Fitzgerald:
Dassen WRM, Kuipers H, Mihl C, et al. Cardiac remodelling: concentric versus eccentric hypertrophy in stregnth and endurance atheletes. Neth Heart J. Apr 2008; 16(4):129-133.
Brendan Maher, in his article “How to Build a Heart” discusses doctor’s and engineer’s research and experimentation into the field of regenerative medicine. Maher talks about several different researchers in this fields. One is Doris Taylor, the director of regenerative medicine at the Texas Heart Institute in Houston. Her job includes harvesting organs such as hearts and lungs and re-engineering them starting with the cells. She attempts to bring the back to life in order to be used for people who are on transplant waiting lists. She hopes to be able to make the number of people waiting for transplants diminish with her research but it is a very difficult process. Maher says that researchers have had some successes when it comes to rebuilding organs but only with simples ones such as a bladder. A heart is much more complicated and requires many more cells to do all the functions it needs to. New organs have to be able to do several things in order for them to be used in humans that are still alive. They need to be sterile, able to grow, able to repair themselves, and work. Taylor has led some of the first successful experiments to build rat hearts and is hopeful of a good outcome with tissue rebuilding and engineering. Scientists have been able to make beating heart cells in a petri dish but the main issue now is developing a scaffold for these cells so that they can form in three dimension. Harold Ott, a surgeon from Massachusetts General Hospital and studied under Taylor, has a method that he developed while training. Detergent is pumped into a glass chamber where a heart is suspended and this detergent strips away everything except a layer of collagen, laminins, and other proteins. The hard part according to Ott is making s...
“Through the isolation and manipulation of cells, scientists are finding ways to identify young, regenerating ones that can be used to replace damaged of dead cells in diseased organs. This therapy is similar to the process of organ transplant, only the treatment consists of the transplantation of cells rather than organs. The cells that have shown by far the most promise of supplying diseased organs with healthy cells are called stem cells.” (Chapter Preface)
Skeletal, smooth, and cardiac muscles play a vital role in the everyday processes that allow the human body to function. Without these muscles, everyday tasks and functions could not be conducted. Injury to these muscles could cause serious problems, however, these muscles have the ability to regenerate, repair, and fix multiple problems all by themselves. Repair and regeneration of a muscle are two similar, yet different things. Repair restores muscle continuity so that it can continue to function in the same way as before injury, but does not completely restore the pre-injury structure like regeneration (Huijbregts, 2001). Muscle repair and regeneration take place after an injury, after surgery, after atrophy, and even after working out.
First generation college students are students who comprise a distinct minority within most institutions of higher learning. These groups of students are the first generation of students in their family lineage to attend a college or university (Allwood, 1966). Due to the lack of family guidance in navigating through the college experience, first generation students face an array of obstacles upon entering the realm of higher education. These students are less likely to obtain their bachelor degree due to finance, family support and retention, all which ultimately limit their college experience. Not only do these students experience issues migrating through high school into college, they also lack the necessary resources some students need to achieve higher standards. For instance financial assistance, mentorship, and other motivating factors that can help a student grow into a professional.
The term, ischemia, denotes inadequate blood supply to tissues due to blockage of the arterial inflow, while, reperfusion injury is defined as the injury caused by the restitution of blood flow after an ischemic peroid, leading to death of cells that were only reversibly injured at the time of blood flow restitution. [63]. The final infarct size after an MI event is therefore the result of the ischemic and reperfusion damage. For this reason, the term that best describes this process of myocyte death in reperfused MI is myocardial ischemia/reperfusion (I/R) injury [64]. In the early hours post myocardial ischemia, injured cardiac cells can release several molecules, including adenosine, opioids, and bradykinin, which activate the G protein signaling pathways therefore promoting myocardial survival. While in the late phase, myocardial ischemia induces upregulation of growth factors and cytokines, including VEGF, ILGF and SDF-1, in the injured myocardium, hence promoting a cardio-protective state. The liver also participates in cardioprotection through the up regulation and release of secretory proteins, including FGF21 and TFF3, which also promote cardiomyocyte survival. [65]. Foundational studies performed about three decades ago with animal models demonstrated that an early reperfusion was able to limit infarct size [66]. Then fibrinolysis was indisputably associated with a decrease in mortality in patients with STEMI [67].A decade later; primary angioplasty was shown to be more superior than fibrinolysis [68]. Currently primary coronary angioplasty (PCI) has been established as the backbone treatment for STEMI patients. The period from the onset of symptoms of MI (representative of the time of coronary occlusion) and reperfusio...
The heart serves as a powerful function in the human body through two main jobs. It pumps oxygen-rich blood throughout the body and “blood vessels called coronary arteries that carry oxygenated blood straight into the heart muscle” (Katzenstein and Pinã, 2). There are four chambers and valves inside the heart that “help regulate the flow of blood as it travels through the heart’s chambers and out to the lungs and body” (Katzenstein Pinã, 2). Within the heart there is the upper chamber known as the atrium (atria) and the lower chamber known as the ventricles. “The atrium receive blood from the lu...
the first heartbeat. For Robert P. George, member of the Presidents Council on Bioethics, in the book Stem Cell Research “The hum...
A number of organs have the intrinsic ability to regenerate, a distinctive feature that varies among organisms. Organ regeneration is a process not fully yet understood however when its underlyning mechanism are unreveled, it holds tremendous therapeutic potential for humans. [28]