Evaluation of the evidence for and against stem cell plasticity Article

Evaluation of the evidence for and against stem cell plasticity - Article Example This can be translated to mean that the highly regenerative tissues have stem cells while those that are poor regenerators lack stem cells (Frank, Schatton & Frank 2010, p. 41). However, cells that have been believed to be non-regenerators such as the heart and the brain have lately shown signs of regeneration. This has opened the doors for researches in stem cell population and their regenerative potential. Studies of tissue injury repair have discovered that there is a strong support for important stem cell functions in the hematopoietic system, dermal epithelium, intestinal epithelium, and skeletal muscle. This is a clear indication that stem cell plasticity can be of high importance in repairing of damaged cells in these tissues (Langer, Vacanti &Lanza 2014, p. 231). Hematopoietic stem cells (HSC) exist predominantly in the bone marrow of human beings. They have always been known to serve the purpose of generation all lineages of mature blood cell types that are needed for the maintenance of proper hematopoietic function (Cetrulo, Cetrulo&Cetrulo 2009, p. 234). However, a series of studies have challenged this assertion. These studies suggest that if bone marrow cells are enriched by hematopoietic stem cell activity, they could appear to be of contribution to the lower levels of multiple nonhematopoietic tissues because of injured or irradiated recipients (Bhattacharya & Stubblefield 2014, p. 199). These studies reveal that these activities can result to nonhematopoietic cells within the skin, intestinal epithelium, lung epithelium, kidney epithelium, pancreas, liver parenchyma, skeletal muscle, and myocardium. Some of the support for the stem cell plasticity comes from opposes of abortion. The main reason as to why this group of people is in support of stem cell plasticity is the fact that a majority of stem cell researchers always use embryos that were created in virto fertility treatment. These are the embryos that were produced but were never used. Most

HES Coursework Example | Topics and Well Written Essays - 1750 words

HES - Coursework Example Drilling fluids are used in offshore oil and gas exploration for a number of reasons, including lubricating the drill bit, cleaning and conditioning the hole, maintaining the pressure of the borehole, as well as washing out rock cuttings out of the borehole to the surface. The drilling fluids is not normally used in its original state, instead, the fluids are mixed with some chemicals in order to maintain their properties. However, there has been an increased concern of the impacts of the drilling fluids and solid cuttings on the environment. GESAMP (1993:18) reported that these solid cuttings and drilling fluids contain hazardous chemical mixture that pose a danger to the environment, particularly to the marine life. As such, there is increased need for solid and gas drilling companies to ensure proper disposal of solid cuttings and drilling fluids as a means of conserving the environment. The main environmental issue linked to the drilling fluids concerns its negative impact on the performance and the continuous accumulation of solid cuttings (AUMS 1989:1). The aim of this paper is to examine some of the environmental issues related to drilling fluid management in light of the various types of drilling fluids. The paper will also explore the negative environmental impacts of improper disposal of drilling waste. Finally, the paper will conclude by discussing measures that oil companies need to take to mitigate the environmental impacts of the drilling fluids. The exploration of offshore oil and gas has intensified in the recent past. This is attributable to the increased need for energy independent. Even though the use of fossil fuel energy has been blamed for the increased production of greenhouse gases that cause global warming, its exploration is not about to end anytime soon. The world will still experience increased exploration of oil and gas (Reis 1996:6). However, the rate at which offshore exploration has increased in the recent past has caused many co ncerns, especially to environmentalists (Australian Petroleum Production & Exploration Association Ltd 1998:51). This is attributable to the magnitude of pollutants generated by the drilling activities. Normally, when exploring offshore oil and gas, engineers normally use the drilling fluid (mud) to lubricate the drill bit, wash out the solid cuttings, condition the hole, as well as to maintain the pressure of the borehole. This is very important for effective exploration of offshore oil and gas, according to Armsworthy, ? Cranford, ?and Lee (2005:8). The drilling fluids used in the exploration of offshore oil and gas are normally not pure. They often contain additives and chemicals meant to enhance the operational property of the final mixture (Cordah Environmental Management Consultants 2000:5). The operational properties enhance using chemicals and additives include density, reactivity, viscosity, ion-exchange parameters, salinity, and fluid loss. Obtaining the right property of the fluid is important for ensuring effective drilling operation. The main types of drilling fluids in use include water-based fluids and non-aqueous fluids. Water-based fluid is a drilling fluid which comprising of a mixture of water,