Tissue Engineering

Tissue Engineering The first time tissue engineering was introduced it gave the promise to repair or replace damaged organs, the field has dramatically evolved from its origins in the late 1980s. Tissue engineering is a field that is rapidly growing and becoming extremely important within biomedical engineering, it mainly links the rapid developments in cellular and molecular biology together with chemical and mechanical engineering. The graph below shows the amount of money the US federal government is spending on different areas of stem cell research. The National institute of health in the United States defined tissue engineering, in other words regenerative medicine as being: An emerging multidisciplinary field involving biology, medicine, and engineering that is likely to revolutionise the ways we improve the health and quality of life for millions of people worldwide by restoring, maintaining, or enhancing tissue and organ function. (1) Tissue engineering is in fact the application of certain scientific principles brought together to enhance the design, modification, construction, growth, and the maintenance of living tissue. Tissue engineering is divided into two main categories. The first being Vitro, this involves the construction of bioartificial tissues from cells isolated by enzymatic dissociation of a specific donor tissue. Bioartificial tissues are ones which are used as an alternative to organ transplantation, these tissues are composed of natural and synthetic substances. The second category of tissue engineering is Vivo, this involves the alteration and variation of cell growth and function. Examples of applications of tissue engineering include, bone and cartilage implants, formation of bioartificial skin and nerve regeneration. Perhaps the most important concept in tissue engineering is stem cell biology. This is the concept which brought back the idea of using cell based approaches for treating diseases such as heart diseases. Research made on stem cells aims to get knowledge on how an organism develops from a single cell and how healthy cells replace damaged cells in adult organisms. Stem cells can be defined as ‘a small subpopulation of the proliferating compartment, consisting of relatively undifferentiated proliferative cells that maintain their population size when they divide while at the same time producing progeny that enter a dividing transit population within which further rounds of cell division occur, together with differentiation events, resulting in the production of the various differentiated functional cells required of the tissue. (6) Stem cells are different to other kinds of cells in the human body. All stem cells have three general properties which contribute to their scientific importance. (1) The first is that they are capable of dividing and renewing themselves for long periods. Other kinds of cells including muscle cells or nerve cells do not normally replicate themselves. Stem cells may replicate many times or proliferate. A population of stem cells that proliferates for many months in laboratory can yield millions of cells. The second property of stem cells is that they are unspecialised, the ability of the cells resulting from proliferation to continue being unspecialised like the parent stem cells makes them capable of long term self renewal. In fact stem cells do not have any tissue specific structures that allow them to perform specialised functions. A stem cell does not have the ability to perform the functions a heart muscle cell or a red blood cell would do. In other words, a stem cell cannot work to pump blood through the body like a heart muscle cell, and it cannot carry oxygen in blood like a red blood cell does. The third property of stem cells is that they have got the potential to differentiate into various cell types in the body, this process happens during early life. When a stem cell divides, new cells formed could either remain as stem cells or become another type of cells with a more specialised function. Unspecialised stem cells develop into specialised cells, including heart muscle cells, nerve cells and others. In research two kinds of stem cells have been used, these are embryonic stem cells and non embryonic stem cells, also called somatic or adult stem cells. Embryonic stem cells are ‘undifferentiated cells derived from a 5 days pre-implantation embryo that are capable of dividing without differentiating for a prolonged period in culture. (1) Embryonic stem cells are mainly derived from embryos that result from eggs that have been fertilised in vitro. Scientists have discovered a method to obtain stem cells from human embryos and then growing them in vitro, these cells are called human embryonic stem cells. Human embryonic stem cells are derived from the blastocyst. These are embryos that are around five days old, the time required for blastocyst formation to start after fertilisation in humans. A non embryonic (Somatic or adult) stem cell is ‘an undifferentiated cell found in many organs and differentiated tissues with a limited capacity for both self renewal (in vitro) and differentiation. (1) Non embryonic cells are undifferentiated cells found in a tissue or an organ that can renew themselves and can differentiate and develop specialised cell types of the specific tissue or organ. This type of stem cells is found in many organs and tissues. Adult stem cells are present in the stem cell niche, this is a specific region of each tissue. The main roles of adult non embryonic stem cells in humans are to maintain and repair the tissue in which they reside. The cells remain inactivated and do not divide for long periods of time until a certain disease or an injury in the tissue in which they reside activates them, and they will then start dividing as more cells are required to maintain the specific tissue. Recently researchers came up with new conditions that would allow specialised adult cells to be genetically programmed in order to be able to differentiate into any type of cell. This type of stem cells is called induced pluripotent stem cells. Pluripotent stem cells have unique special characteristics that make them very useful in a wide range of applications. They have the ability to replace damaged cells and provide a new potential for treating disease. They are used in the treatment of extensive burns, and to restore the blood system in patients with diseases such as Leukaemia and other blood disorders. Stem cells can be used to study the development of humans from a fertilised egg and all the processes involved, scientists could Identify the mechanisms that determine whether a stem cell chooses to replicate itself or to differentiate into a specific cell type, and if that is the case what cell type would it be, these information would allow scientists to find out and understand what controls normal human development. In practice a more complete understanding of the genetic and molecular control of these processes may provide scientists with helpful information about how certain diseases arise. This allows scientists to suggest new ways of treating those diseases. The exceptional property of human embryonic and induced pluripotent stem cells that they can renew themselves while maintaining the ability to differentiate into useful cell types. For example, they have been used as a source of human cardiomyocytes. This allowed scientists to go further in research by using those cardiomyocytes in cell based cardiac therapies, cardiomyocytes have also been used in modeling human heart development and in testing drugs. (4) Also stem cells have the ability to provide a source of insulin producing cells, or repair the damaged the pancreatic tissues. This provides another potential to treat diabetes. (5) New medications could be tested for safety on specific cells that perform special functions. A large number of the specific type of cells on which the medications are to be tested is generated from stem cells. Stem cells have the ability to replace cells lost due to other devastating diseases for which no cures have been found yet. Today donated tissues and organs are often used to replace the specific damaged tissues or organs. The problem with that is the fact that, the need for transplantable tissues and organs is a lot more than the supply available. Stem cells, with the ability to differentiate into specific cell types could offer the possibility of providing a renewable source of replacement cells and tissues to treat diseases and replace the damaged tissues and organs. However significant technical barriers concerning stem cells remain, but they are to be overcome by research which is increasing in both importance and scope due to the huge benefits that could be obtained. References: 1- www.stemcells.nih.gov 2- Tissue engineering, Bernhard O. Palsson and Sangeeta N. Bhatia. 3- Principles of tissue engineering / edited by Robert P. Lanza, Robert Langer, Joseph Vacanti, 2nd edition. 4- Cardiac applications for human pluripotent stem cells. Shiba Y, Hauch KD, Laflamme MA. www.Pubmed.gov 5- Adipose tissue derived stem cells for regeneration and differentiation into insulin-producing cells. Kim SC, Han DJ, Lee JY. www.pubmed.gov 6- Essentials of stem cell biology [electronic resource] / editors, Robert Lanza †¦ [et al.]. 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Garlic: A Taste for Health :: Botany

Garlic: A Taste for Health Culinary garlic is one of the most medically studied herbs today. it has been cultivated since the Neolithic period around 10,000 BC. This bulb has flavored the food of hunters and nomads after the discovery of its intensively robust flavor. The summarians (2600 BC-2100 BC) were actively practicing the healing powers of garlic, and some believe the summarians to have introduced garlic to China, from where it later spread to Japan and Korea. However, some taxonomists believe garlic to be endemic to China. Records have indicated that the medicinal respect for garlic was not fully appreciated in regions of India, China, as well as in southern Europe. The summarians had been using garlic for some time before others caught on to its medicinal success. Many cultures have remedied various ailments with this potent herb. The Egyptians, documented on a papyrus dating back to 1500 BC, prescribed garlic for 22 diseases (1). And according to the 5th century Greek historian Herodotus, the Egyptians had carved an inscription into the great pyramid of King Khufu (Cheops) detailing the amount of garlic, onions, and radishes eaten by the slaves during the twenty-year building period. Egyptians slaves caused the first ever-recorded strike when a ration of garlic did not turn up on time (1). The slaves ate garlic to increase their stamina and to maintain their over-all health. Cloves of garlic have been found in the tomb of Tutankamen who ruled Egypt until 1338 BC. And the Egyptians were not the only ones to worship garlic. According to Theophrastus, ancient Greeks offered garlic on piles of stones at crossroads as a supper for Hecate, god of the underworld. The Bible has even mentioned the Israelites, delivered out of bondage by Moses, complaining of their food and wishing for the same things they had been eating while they were slaves: "Oh, that we had some of the delicious fish we enjoyed so much in Egypt, and the wonderful cucumbers and melons, leeks, onions, and garlic!" (Numbers 11:5, The Living Bible; 2). This pungent herb is also mentioned in the literature of other great kingdoms: Babylon, Medo-Persia, Greece, and Rome (2). Garlic can be found medically prescribed in ancient texts as far back as 1550 BC (1). Garlic was always an ingredient in potions thought to cure external and internal disease (1). The ancient Greeks and Romans used the herb from anything like repelling scorpions to curing bladder infections.

Importance of nutrition during the Infancy and Toddler-hood period Essay

Children are a blessing from God and it is therefore important that we ensure that those bundles of joy are well taken care of. Infants are generally taken to be children from birth to around one year, and it becomes therefore important to give them utmost care since they are at their most vulnerable stage in life. This care should not only be confined to attention and love but most importantly should be the focus of what and how best to feed the infant. Scientists have expressed their belief that what we feed our infants might have drastic consequences later in life. These consequences include such conditions as diabetes and obesity and the rampant rate of obesity in developed countries might just be a reflection of the inability of parents to feed their children’s appropriately (Fallows & Kingham, 2005). Doctors have stated categorically that child4ren should be fed milk only during the first six months of their lives and it should be noted that faulting this wise counsel could risk the health of these infants in the future. Breast milk contains all the vital nutrients that an infant need in order to grow and appropriate vitamins to boost his/her immune system top fend off diseases. It is important to note that while it is advisable to feed the infant using breast milk, infants could also be fed with formula as a supplement of breast milk. There are many reasons why many mothers choose to use formula to feed their babies. Some simply find out that breastfeeding does not work for them either for psychological or practical reasons. The demands of life that leads to very busy lifestyles work against the need for mothers to be with their children full time and formula simply happens to be a better alternative. However, there are still those who express their breast milk in feeding bottles and the milk is fed to the infant by someone else who is available to care for the toddler (Ward, 2009). Infants usually need to feed eight to twelve times in a day since they are growing rapidly and the proteins inside the milk are a vital component for this growth. For those with infants who sleep a lot, it is advisable to wake them regularly in order to feed the since failure to do so might hamper their growth. It is also recommended that parents take their babies to the clinic to have them weighed and observed to ensure that they are growing in a healthy manner and acquire vital information about how best to take care of their babies. There are signs to observe during the sixth month to signify that the infant is ready to start being weaned. This include such period when the baby can sit up, baby does not reject the food put in its mouth, can pick up food stuffs and stuff it into the mouth and an increased appetite for milk. Babies should be weaned slowly with a meal per day and it is important to continue breast feeding at least till one year. Some of the food which one can feed and infant include cereals, soft fruits, rice and vegetables that can be crushed. However, around 10 months infants are ready to be introduced to adult foods but such a transition should be handled with utmost care. As the baby becomes a toddler a period which lasts from between 12 months to 24 months, his food needs increases. During this period the toddler starts to walk and he requires increased proteins for growth and energy foods to sustain his activities. At this period toddlers may change their eating habits due to changes in growth patterns. Moreover, toddlers become choosy when it comes to certain foods and it is nothing to do with illness. Again, parents needs top be careful about the food they feed the infants and toddlers since some of them might be allergic and impair the health of this babies. They should therefore make a point of seeking information diligently about how best to feed their children (Papalia, Wendkos & Duskin, 2007). References Fallows,C. & Karen Kingham, K. (2005). Baby & Toddler Food. Murdoch books. Papalia, D. , Wendkos S. & Duskin, R. (2007). A Child’s World: Infancy through Adolescence:11th Ed. McGraw-Hill Ward, E. (2009). What to Feed Your Baby and Toddler. Retrieved May 17, 2009 from http://children. webmd. com/guide/what-to-feed-your-baby-toddler.

Definition and Examples of Hypernyms in English

In  linguistics  and  lexicography, a  hypernym is a  word whose meaning includes the meanings of other words. For instance, flower is a hypernym of daisy and rose. Adjective:  hypernymous. Put another way, hypernyms (also called superordinates and supertypes) are general words; hyponyms  (also called subordinates) are subdivisions of more general words. The semantic relationship between each of the more specific words (e.g., daisy and rose) and the more general term (flower) is called hyponymy or inclusion. Etymology From the Greek, extra name Examples and Observations [A] hypernym is a broad, superordinate label that applies to many members of a set, while the members themselves are the hyponyms. Hyponymy is a hierarchical relationship, and it may consist of a number of levels. For example, dog is a hyponym of animal, but it is also the hypernym of poodle, alsatian, chihuahua, terrier, beagle and so on. (Jan McAllister and James E. Miller, Introductory Linguistics for Speech and Language Therapy Practice. Wiley-Blackwell, 2013) A hypernym is a word with a general meaning that has basically the same meaning of a more specific word. For example, dog is a hypernym, while collie and chihuahua are more specific subordinate terms. The hypernym tends to be a basic-level category that is used by speakers with high frequency; speakers usually refer to collies and chihuahuas as dogs, rather than using the subordinate terms, which are consequently of relatively low frequency. (Laurie Beth Feldman, Morphological Aspects of Language Processing. Lawrence Erlbaum, 1995) The foot of footstep narrows down the type of step being expressed to the step made by a foot. A footstep is a kind of step; or, in more technical terms, footstep is a hyponym, or subtype, of step, and step is a hypernym, or supertype, of footstep. . . . Doorstep is also a hyponym of step, and step is a hypernym of doorstep. (Keith M. Denning, Brett Kessler, and William Ronald Leben, English Vocabulary Elements. Oxford University  Press, 2007) Hypernyms, Hyponyms, and Connotations Hyponyms are more likely to carry  strong connotations than  hypernyms, though this is not an invariable rule. The word animal can carry negative connotations in metaphors such as He behaved like an animal. However, more specific connotations can be carried by the use of more specific words. He ate like a pig. You rat! Shes a bitch. (Maggie Bowring et al.,  Working with Texts: A Core Introduction to Language Analysis.  Routledge, 1997) A Method of Definition The most illuminating way of defining a lexeme is to provide a hypernym along with various distinguishing features—an approach to definition whose history can be traced back to Aristotle. For example, a majorette is a girl (the hypernym) who twirls a baton and accompanies a marching band. It is usually possible to trace a hierarchical path through a dictionary, following the hypernyms as they become increasingly abstract until we arrive at such general notions (essence, being, existence) that clear sense-relations between the lexemes no longer exist. (David Crystal, The Cambridge Encyclopedia of the English Language. Cambridge University  Press, 2003) Alternate Spellings: hyperonym