Dictyostelium as a Predictive Model for Bitter Tastant

Dictyostelium as a Predictive Model for Bitter Tastant Developing Dictyostelium as a Predictive Model for Bitter Tastant Identification INTRODUCTION Bitter tastant (emetic) research utilises a variety of animal models for the identification of the emetic susceptibility of novel compounds and aim to characterise the underlining mechanisms that give rise to emesis. There are two categories of animals used in this type of research, those that have the ability to vomit (ferrets, dogs and cats), and those that lack the emetic reflex (rats and mice) (Holmes et al., 2009). In addition to this, there is a different sensitivity to emetic compounds amongst these animal models, due to the existence of multiple pathways for the emesis induction. There are also differences in the receptor pharmacology and distribution, and metabolic pathway regulation. This makes it very hard to use a unique animal model for emetic research, pushing research towards a multi-model approach, therefore increasing the utilisation of animals (Robery et al., 2011). Ingestion of bitter tastants can lead to innate aversive behaviour, reduced gastric emptying, nausea and vomiting in mammals and as such bitter tastants are thought to provide a potentially vital warning sign of toxicity (Robery et al., 2011). Humans recognise thousands of different compounds as bitter. Despite this ability only around 25 taste 2 receptors (TAS2R) have been identified. Common bitter ligands include cycloheximide, denatonium, PROP (6-n-propyl-2-thiouracil), PTU (phenylthiourea), and ÃŽ ²-glucopyranosides (Meyerhof et al., 2010). As previously stated, bitter substances are detected by a specific subset of taste receptors, known as BITTER TASTE-SENSING TYPE 2 receptors (TAS2Rs) (Meyerhof et al., 2010). These are part of the superfamily of G protein-coupled receptors (GPCRs) and can be found on cell surface that mediate gustatory taste perception on the tongue. Signal transduction of bitter stimuli is accomplished via the ÃŽ ±-subunit of gustducin (Gulbransen et al., 2009). This G protein subunit activates a taste phosphodiesterase and decreases cyclic nucleotide levels. The ÃŽ ²ÃŽ ³-subunit of gustducin also mediates taste by activating IP3 (inositol triphosphate) and DAG (diglyceride). These second messengers may open gated ion channels or may cause release of internal calcium. Although all TAS2Rs are located in gustducin-containing cells, knockout of gustducin does not completely abolish sensitivity to bitter compounds, suggesting a redundant mechanism for bitter tasting (unsurprising given that a bitter tas te generally signals the presence of a toxin). One proposed mechanism for gustducin-independent bitter tasting is via ion channel interaction by specific bitter ligands, similar to the ion channel interaction which occurs in the tasting of sour and salty stimuli (Gulbransen et al., 2009). The properties of TAS2Rs are different from other GPCRs, because of the ability of binding a wide range of compounds with low specificity and affinity. TAS2Rs have recently been suggested to have important extra-oral functions in the respiratory and gastrointestinal tracts. In the human airway epithelium TAS2Rs are expressed on the solitary chemosensory cells and ciliated epithelial cells, where they sense chemical irritation and promote ciliary beat frequency, respectively. Thus TAS2Rs may be protective and part of the defence against inhaled noxious compounds (Zhang et al., 2013). Recent studies have found that in resting primary airway smooth muscle cells, bitter tastant activate TAS2R-dependent signalling pathway that results in an increase in [Ca2+]i levels, although to a level much lower than that caused by bronchoconstrictors (2-adrenoceptor agonist) (Zhang et al., 2013). Under physiological circumstances, bitter tastants can activate TAS2Rs to modestly increase [Ca2+]i levels without affecting contraction, but in the situation of muscle constriction, they can block L-type calcium channels to induce bronchodilation (Zhang et al., 2013). TAS2R agonists showed both greater relaxation and inhibition of airway hyper-responsiveness than a ÃŽ ²2-adrenoceptor agonist in mouse airways. Given the large selection of known natural and synthetic agonists recognized by the 25 TAS2Rs, the findings have introduced bitter taste receptors as a potential new family of targets for asthma pharmacotherapy (Zhang et al., 2013). Dictyostelium as  a biomedical model organism D. Discoideum is a well-established research model organism, especially in investigating chemotaxis. D. Discoideum is a social amoeba that feeds on bacteria as its staple food source. Once the food supply is exhausted, cells start a developmental program leading to the production of spores that are able to survive in hostile conditions (Frey et al., 2007). Starving cells produce a chemo-attractant, cyclic AMP (cAMP), which serves as a signal for 1 x 105 neighbouring cells to aggregate, which then develop into a mature fruiting body (after 24 hours), where 20% of the cells form a stalk that supports a spore head incorporating 80% of the remaining cells as spores. When food sources are available again, the spores germinate into amoebae, completing the life cycle (Figure 1) (Frey et al., 2007). (Frey et al., 2007) Figure 1 D. Discoideum, develops from a single vegetative amoebae (0hrs) through to the generation of the mature fruiting body (24hrs). Aggregation is caused by the chemotaxis of cells toward cAMP waves to give rise to a multicellular aggregate. Aggregation results in the creation of a mound, then a tipped mound, and as development proceeds, the tip prolongate and forms a finger. Ultimately, the finger collapses to form a slug or continues to form a fruiting body. During final stage of the development, the cells differentiate into vacuolated stalk cells that sustain a spore head containing spores, which can tolerate a wider range of environmental conditions. The full developmental process from starvation of vegetative cells to the formation of a mature fruiting body is accomplished in 24 h (Frey et al. 2007). D. Discodeum has been extensively utilised to investigate a range of fundamental biological processes such as cell migration, signal transduction, phagocytosis and signalling during morphogenesis and cell differentiation. The fully sequenced genome contains 34 Mb of DNA (84-fold smaller than the human genome). D. Discoideum has a genome that encodes for a variety of proteins that are human homologues, associated with a variety of disorders (Boeckeler et al., 2007). Therefore, it has been suggested that the primary role of those proteins can be analysed in the model to understand their related disease function. Nausea and vomiting are common but serious side effects associated with many therapeutic drugs. Whilst the physiological mechanisms behind the generation of the vomiting response are well characterised, the diverse range of emetic stimuli that can generate the response are poorly understood. The potential of using D. Discoideum, a eukaryotic amoeba, as a model for predicting emetic liability was examined in this thesis. The effects of a diverse range of known emetic and aversive compounds on Dictyostelium cell behaviour was investigated, resulting in the identification of a small number that strongly inhibit cell behaviour in a concentration-dependent manner. Recent studies using Dictyostelium as a simple model system for bitter related (emetic) research has shown the validity of using this approach for the reduction of animals in testing for emetic liability. Even though Dictyostelium does not contain genes encoding homologues to T2R proteins associated with bitter compounds detection, it has been identified the molecular mechanism responsible of PTU detection. The screening of mutants resistant to the effects of PTU on growth identified a putative G-protein coupled receptor mutant, GrlJ-. Translation of this discovery to human context identified an uncharacterised human gamma-aminobutyric acid (GABA) type B isoform, with a relatively weak homology to GrlJ. The expression of the human GABA-B receptor restored GrlJ- sensitivity to PTU, implicating this human protein as a novel receptor for PTU. In addition, GrlJ only partially controls PTU detection but not detection for all bitter substances. This research was carried out by monitoring the cell behaviour (motility, circularity, protrusions formation and displacement) following exposure to a range of known emetic compounds. Results show that bitter tastants cause an acute, marked and concentration dependent effect on cell behaviour. Therefore, this suggests that Dictyostelium may guarantee a new model for the analysis and screening of novel bitter/emetic compounds, and therefore reducing the utilisation of animal models by identifying the best candidates in a range of molecules. In this study a range of eight compounds were tested to investigate their effects on Dictyostelium random cell movement. The compounds list was specifically created to understand if the model system was able to predict the bitterness of those compounds and ultimately obtain a ranking order comparable to the in vivo rat brief access taste aversion (BATA) and human sensory panel models (Rudnitskaya, et al., 2013). The set of substances consisted of both organic and inorganic – azelastine, caffeine, chlorhexidine, potassium nitrate, paracetamol, quinine and sumatriptan. Results have shown that the bitterness ranking order obtained by using random cell movement assays was comparable to the one obtained with the BATA and the human sensory panel models. In particular, amongst those compounds, Azelastine, a selective (non-sedating) H1 antagonist structurally similar to other anti-histaminic molecules has shown to be one of the most potent compounds in the inhibition of Dictyostelium cell behaviour. This bitter-tasting compound is pharmacologically classified as a 2gen antihistamine, with relative lack of CNS (central nervous system) activity. Clinical trials, in vitro and in vivo studies have shown the combined effect of direct inhibition and stabilisation of inflammatory cells. In vitro studies suggest that the affinity of azelastine for H1 receptors is several times higher than that of chlorpheniramine, a 1gen H1 antagonist. Azelastine directly antagonizes TNF-ÃŽ ±, leukotrienes, endothelin-1, and platlet-activating factor. In vivo studies in a guinea pig model have demonstrated that both histamine-related and h-independent bronchoconstriction were inhibited by azelastine (Williams et al., 2010). The second most potent compound tested is Chlorhexidine (CHX), a broad spectrum antimicrobial agent, frequently used in dental-care to inhibit bacterial growth and in periodontal disease prophylaxis. It is classified as antibacterial, but it can also interfere with the proteolytic activity of some periodontal pathogens. This inhibitory effect is associated with its chelating properties (Trufello et al., 2014). One of the chemicals used as standard for bitterness measurements is Quinine, a natural occurring alkaloid with different medicinal properties, such as antipyretic, antimalarial, analgesic, and anti-inflammatory activities. Methods D. discoideum discoideum maintenance Cells and spores were stored at -80  ºC, and every month an aliquot of the frozen stock was collected and placed on a Raoutella planticola bacterial lawn. After 3-4 days, plaques of growth were visible, which were then scraped and transferred into liquid dishes. Culture dishes were kept in absolute sterile conditions at the constant temperature of 21  ºC. Cells needed for experiments were transferred into shaking cultures (120 rpm/min) or washed off every 2 days. In order to make shaking cultures, cells were washed off the plate, transferred to a G0 media (Ax medium containing 100 µ/ml Penicillin and 100 µg/ml Streptomicin), and kept in the shaking incubator at 21  ºC and counted and or diluted every day. Cells were utilised for experiments after 2-3 days of shaking and flasks were kept for one week before replacing them with fresh cultures. The liquid content in flasks was 1/5 of the total flask volume, in order to maintain ideal growth conditions (oxygen and surface area) , and they were be kept between 2 and 5 x 106. Development assay Dictyostelium development assays were performed in triplicate experiments. Cells were plated onto membranes at the concentration of 1 x 107 per membrane (in KK2), then the membranes were transferred onto millipore filters embedded with the selected drug. Cells were placed in small petri dishes (6 cm diameter) and kept at 22  ºC for 24 hours in humid environmental conditions. Development images were taken after 24 hours at different magnification resolutions (x2, x3.2, and x4 side at 45-degree angle). D. discoideum Permanent stock At least 1 x 107 cells were collected from fresh culture plate, and resuspendend in 200ÃŽ ¼l D. discodeum freezing medium (7% DMSO, Horse serum), and frozen to -80 ºC using isopropanol freezing containers for two hours, then stored at -80  ºC in liquid nitrogen. Live cell microscopy To prepare D. discodeum cells (Ax2) for behaviour analysis experiments, cells were grown in shaking suspension in Axenic medium (Formedium Co. Ltd, Norfolk, UK) for at least 48hrs. Cells were washed and resuspended in phosphate buffer at 1.7 x 106 cells/ml. Cells were then pulsed for 5 hours with 30 nM cAMP at 6 min intervals whilst shaking at 120 rpm. Cells were then washed in phosphate buffer, resuspended at 1.7105 cells/ml, and 250  µL aliquots of cells were added to into a Lab-Tek 8-well chambered coverglass wells (Thermo Fisher, Leicestershire, UK), and allowed to adhere for 10-15 min, and for each experiment double concentrated drugs (250  µl) were administrated at the 15th frame by using a P1000. Cells movement was investigated using an Olympus IX71 microscope at 40X magnification, and images were recorded with a QImaging RetigaExi Fast1394 digital camera. Images were acquired every 15 seconds over a 15 min period for each compound, and at each concentration, with a minimu m of three independent experiments for each drug/concentration and an average cell number of 10 cells quantified per experiment. Solvent only controls were carried out for all experiments to ensure readouts were based upon compounds listed, with for example, no effect of DMSO shown at 1% – the highest concentration used in the experiments described here. References Ayana Wiener; Marina Shudler; Anat Levit; Masha Y. Niv. BitterDB: a database of bitter compounds. Nucleic Acids Res 2012, 40(Database issue):D413-419. Bachmanov AA, Beauchamp GK (2007). Taste Receptor Genes. Annual Review of Nutrition 27: 389–414. Choi, D.H. et al., 2013. Evaluation of taste-masking effects of pharmaceutical sweeteners with an electronic tongue system. Drug development and industrial pharmacy, 9045, pp.1–10. Available at: http://www.ncbi.nlm.nih.gov/pubmed/23786206 [Accessed October 10, 2013]. Finger, T.E. Kinnamon, S.C., 2011. Taste isn’t just for taste buds anymore. F1000 biology reports, 3(September), p.20. Available at: http://www.pubmedcentral.nih.gov/articlerender.fcgi?artid=3169900tool=pmcentrezrendertype=abstract [Accessed December 9, 2013]. Finger, T.E. Kinnamon, S.C., 2011. Taste isn’t just for taste buds anymore. F1000 biology reports, 3(September), p.20. Available at: http://www.pubmedcentral.nih.gov/articlerender.fcgi?artid=3169900tool=pmcentrezrendertype=abstract [Accessed December 9, 2013]. Gulbransen, B. D., Clapp, T. R., Kinnamon, S. C., Finger, T. E. (2009). NIH Public Access, 99(6), 2929–2937. doi:10.1152/jn.00066.2008.Nasal Holmes, a M., Rudd, J. a, Tattersall, F. D., Aziz, Q., Andrews, P. L. R. (2009). Opportunities for the replacement of animals in the study of nausea and vomiting. British Journal of Pharmacology, 157(6), 865–80. doi:10.1111/j.1476-5381.2009.00176.x Margolskee, R.F., 2002. Molecular mechanisms of bitter and sweet taste transduction. The Journal of biological chemistry, 277(1), pp.1–4. Available at: http://www.ncbi.nlm.nih.gov/pubmed/11696554 [Accessed December 4, 2013]. Meyerhof, W. et al., 2010. The molecular receptive ranges of human TAS2R bitter taste receptors. Chemical senses, 35(2), pp.157–70. Available at: http://www.ncbi.nlm.nih.gov/pubmed/20022913 [Accessed October 17, 2013]. Pulkkinen, V. et al., 2012. The bitter taste receptor (TAS2R) agonists denatonium and chloroquine display distinct patterns of relaxation of the guinea pig trachea. American journal of physiology. Lung cellular and molecular physiology, 303(11), pp.L956–66. Available at: http://www.ncbi.nlm.nih.gov/pubmed/22962016 [Accessed September 19, 2013]. Pulkkinen, V. et al., 2012. The bitter taste receptor (TAS2R) agonists denatonium and chloroquine display distinct patterns of relaxation of the guinea pig trachea. American journal of physiology. Lung cellular and molecular physiology, 303(11), pp.L956–66. Available at: http://www.ncbi.nlm.nih.gov/pubmed/22962016 [Accessed September 19, 2013]. Robery, S. et al., 2011. Investigating the effect of emetic compounds on chemotaxis in Dictyostelium identifies a non-sentient model for bitter and hot tastant research. PloS one, 6(9), p.e24439. Available at: http://www.pubmedcentral.nih.gov/articlerender.fcgi?artid=3169598tool=pmcentrezrendertype=abstract [Accessed October 10, 2013]. Rudnitskaya, A. et al., 2013. Assessment of bitter taste of pharmaceuticals with multisensor system employing 3 way PLS regression. Analytica chimica acta, 770, pp.45–52. Available at: http://www.ncbi.nlm.nih.gov/pubmed/23498685 [Accessed October 10, 2013]. Ueda, T. et al., 2003. Functional interaction between T2R taste receptors and G-protein alpha subunits expressed in taste receptor cells. The Journal of neuroscienceà ¢Ã¢â€š ¬Ã‚ ¯: the official journal of the Society for Neuroscience, 23(19), pp.7376–80. Available at: http://www.ncbi.nlm.nih.gov/pubmed/12917372. Wiener, A. et al., 2012. BitterDB: a database of bitter compounds. Nucleic acids research, 40(Database issue), pp.D413–9. Available at: http://www.pubmedcentral.nih.gov/articlerender.fcgi?artid=3245057tool=pmcentrezrendertype=abstract [Accessed October 17, 2013]. Williams, P.B., Crandall, E. Sheppard, J.D., 2010. Azelastine hydrochloride, a dual-acting anti-inflammatory ophthalmic solution, for treatment of allergic conjunctivitis. Clinical Ophthalmology, p.993. Available at: http://www.dovepress.com/azelastine-hydrochloride-a-dual-acting-anti-inflammatory-ophthalmic-so-peer-reviewed-article-OPTH [Accessed February 3, 2014]. Zhang, C.-H., Lifshitz, L. M., Uy, K. F., Ikebe, M., Fogarty, K. E., ZhuGe, R. (2013). The cellular and molecular basis of bitter tastant-induced bronchodilation. PLoS Biology, 11(3), e1001501. doi:10.1371/journal.pbio.1001501 Available at: http://www.pubmedcentral.nih.gov/articlerender.fcgi?artid=3589262tool=pmcentrezrendertype=abstract [Accessed October 15, 2013]. Trufello, a M. et al., 2014. Subclinical concentrations of chlorhexidine inhibit gelatinase activity of carious dentine in vitro. Australian dental journal, pp.1–6. Available at: http://www.ncbi.nlm.nih.gov/pubmed/24494744 [Accessed February 10, 2014].

Computerized Library System Essay

Chromosomal aberrations are disruptions in the normal chromosomal content of a cell and are a major cause of genetic conditions in humans, such as Down syndrome, although most aberrations have little to no effect. Some chromosome abnormalities do not cause disease in carriers, such as translocations, or chromosomal inversions, although they may lead to a higher chance of bearing a child with a chromosome disorder. Abnormal numbers of chromosomes or chromosome sets, called aneuploidy, may be lethal or may give rise to genetic disorders. Genetic counseling is offered for families that may carry a chromosome rearrangement. The gain or loss of DNA from chromosomes can lead to a variety of genetic disorders. Human examples include: * Cri du chat, which is caused by the deletion of part of the short arm of chromosome 5. â€Å"Cri du chat† means â€Å"cry of the cat† in French; the condition was so-named because affected babies make high-pitched cries that sound like those of a cat. Affected individuals have wide-set eyes, a small head and jaw, moderate to severe mental health issues, and are very short. * Down syndrome, the most common trisomy, usually caused by an extra copy of chromosome 21 (trisomy 21). Characteristics include decreased muscle tone, stockier build, asymmetrical skull, slanting eyes and mild to moderate developmental disability.[51] * Edwards syndrome, or trisomy-18, the second-most-common trisomy.[citation needed]Symptoms include motor retardation, developmental disability and numerous congenital anomalies causing serious health problems. Ninety percent of those affected die in infancy. They have characteristic clenched hands and overlapping fingers. * Isodicentric 15, also called idic(15), partial tetrasomy 15q, or inverted duplication 15 (inv dup 15). * Jacobsen syndrome, which is very rare. It is also called the terminal 11q deletion disorder.[52] Those affected have normal intelligence or mild developmental disability, with poor expressive language skills. Most have a bleeding disorder called Paris-Trousseau syndrome. * Klinefelter’s syndrome (XXY). Men with Klinefelter syndrome are usually sterile, and tend to be taller and have longer arms and legs than their peers. Boys with the syndrome are often shy and quiet, and have a higher incidence of speech delay and dyslexia. Without testosterone treatment, some may develop gynecomastia during puberty. * Patau Syndrome, also called D-Syndrome or trisomy-13. Symptoms are somewhat similar to those of trisomy-18, without the characteristic folded hand. * Small supernumerary marker chromosome. This means there is an extra, abnormal chromosome. Features depend on the origin of the extra genetic material. Cat-eye syndrome and isodicentric chromosome 15 syndrome (or Idic15) are both caused by a supernumerary marker chromosome, as is Pallister-Killian syndrome. * Triple-X syndrome (XXX). XXX girls tend to be tall and thin and have a higher incidence of dyslexia. * Turner syndrome (X instead of XX or XY). In Turner syndrome, female sexual characteristics are present but underdeveloped. Females with Turner syndrome often have a short stature, low hairline, abnormal eye features and bone development and a â€Å"caved-in† appearance to the chest. * XYY syndrome. XYY boys are usually taller than their siblings. Like XXY boys and XXX girls, they are more likely to have learning difficulties. * Wolf-Hirschhorn syndrome, which is caused by partial deletion of the short arm of chromosome 4. It is characterized by severe growth retardation and severe to profound mental health issues. Cri du chat syndrome, also known as chromosome 5p deletion syndrome, 5p minus syndrome or Lejeune’s syndrome, is a rare genetic disorder due to a missing part ofchromosome 5. Its name is a French term (cat-cry or call of the cat) referring to the characteristic cat-like cry of affected children. It was first described by Jà ©rà ´me Lejeune in 1963.[1] The condition affects an estimated 1 in 50,000 live births, strikes all ethnicities, and is more common in females by a 4:3 ratio. Signs and symptoms The syndrome gets its name from the characteristic cry of affected infants, which is similar to that of a meowing kitten, due to problems with the larynx and nervous system. About 1/3 of children lose the cry by age 2. Other symptoms of cri du chat syndrome may include: * feeding problems because of difficulty swallowing and sucking. * low birth weight and poor growth. * severe cognitive, speech, and motor delays. * behavioral problems such as hyperactivity, aggression, tantrums, and repetitive movements. * unusual facial features which may change over time. * excessive drooling. * constipation. ————————————————- Genetics Cri du chat syndrome is due to a partial deletion of the short arm of chromosome number 5, also called â€Å"5p monosomy†. Approximately 90% of cases results from a sporadic, or randomly-occurring, de novo deletion. The remaining 10-15% are due to unequal segregation of a parental balanced translocation where the 5p monosomy is often accompanied by a trisomic portion of the genome. These individuals may have more severe disease than those with isolated monosomy of 5p. Most cases involve total loss of the most distant 20-10% of the material on the short arm. Fewer than 10% of cases have other rare cytogenetic aberrations (e.g., interstitial deletions, mosaicisms, rings and de novo translocations). The deleted chromosome 5 is paternal in origin in about 80% of de novo cases. Loss of a small region in band 5p15.2 (cri du chat critical region) correlates with all the clinical features of the syndrome with the exception of the catlike cry, which maps to band 5p15.3 (catlike critical region). The results suggest that 2 noncontiguous critical regions contain genes involved in this condition’s etiology. Two genes in these regions, Semaphorine F (SEMA5A) and delta catenin(CTNND2), are potentially involved in cerebral development. The deletion of the telomerase reverse transcriptase (hTERT) gene localized in 5p15.33 may contribute to the phenotypic changes in cri du chat syndrome as well. people with cri du chat syndrome Down syndrome (DS) or Down’s syndrome, also known as trisomy 21, is achromosomal condition caused by the presence of all or part of a third copy ofchromosome 21.[1] Down syndrome is the most common chromosome abnormality in humans.[2] It is typically associated with a delay in cognitive ability (mental retardation, or MR) and physical growth, and a particular set of facial characteristics.[1] The average IQ of young adults with Down syndrome is around 50, compared to children without the condition with an IQ of 100.[1][3] (MR has historically been defined as an IQ below 70.) A large proportion of individuals with Down syndrome have a severe degree of intellectual disability. Genetics Karyotype for trisomy Down syndrome. Notice the three copies of chromosome 21 Down syndrome disorders are based on having too many copies of the genes located on chromosome 21. In general, this leads to an overexpression of the genes.[54] Understanding the genes involved may help to target medical treatment to individuals with Down syndrome. It is estimated that chromosome 21 contains 200 to 250 genes.[55] Recent research has identified a region of the chromosome that contains the main genes responsible for the pathogenesis of Down syndrome.[56] The extra chromosomal material can come about in several distinct ways. A typical human karyotype is designated as 46,XX or 46,XY, indicating 46 chromosomes with an XX arrangement typical of females and 46 chromosomes with an XY arrangement typical of males.[57] In 1–2% of the observed Down syndromes.[58] some of the cells in the body are normal and other cells have trisomy 21, this is called mosaic Down syndrome (46,XX/47,XX,+21).[59] [60] Trisomy 21 Trisomy 21 (47,XX,+21) is caused by a meiotic nondisjunction event. With nondisjunction, agamete (i.e., a sperm or egg cell) is produced with an extra copy of chromosome 21; the gamete thus has 24 chromosomes. When combined with a normal gamete from the other parent, the embryo now has 47 chromosomes, with three copies of chromosome 21. Trisomy 21 is the cause of approximately 95% of observed Down syndromes, with 88% coming from nondisjunction in the maternal gamete and 8% coming from nondisjunction in the paternal gamete.[58] The actual Down syndrome â€Å"critical region† encompasses chromosome bands 21q22.1-q22.3.[61] Edwards syndrome (also known as Trisomy 18 (T18) or Trisomy E) is a genetic disordercaused by the presence of all or part of an extra 18th chromosome. It is named after John H. Edwards, who first described the syndrome in 1960.[1] It is the second most commonautosomal trisomy, after Down syndrome, that carries to term. Edwards syndrome occurs in around one in 6,000 live births and around 80 percent of those affected are female.[2] The majority of fetuses with the syndrome die before birth.[2]The incidence increases as the mother’s age increases. The syndrome has a very low rate of survival, resulting from heart abnormalities, kidney malformations, and other internal organ disorders. Signs and symptoms Children born with Edwards syndrome may have some or all of the following characteristics: kidney malformations, structural heart defects at birth (i.e., ventricular septal defect, atrial septal defect, patent ductus arteriosus), intestines protruding outside the body (omphalocele), esophageal atresia, mental retardation, developmental delays, growth deficiency, feeding difficulties, breathing difficulties, and arthrogryposis (a muscle disorder that causes multiple joint contractures at birth).[3][4] Some physical malformations associated with Edwards syndrome include small head (microcephaly) accompanied by a prominent back portion of the head (occiput); low-set, malformed ears; abnormally small jaw (micrognathia); cleft lip/cleft palate; upturned nose; narrow eyelid folds (palpebral fissures); widely spaced eyes (ocular hypertelorism); drooping of the upper eyelids (ptosis); a short breast bone; clenched hands; choroid plexus cysts; underdeveloped thumbs and or nails,absent radius, webbing of the second and third toes; clubfoot or Rocker bottom feet; and in males, undescended testicles. of choroid plexus cysts, which are pockets of fluid on the brain. These are not problematic in themselves, but their presence may be a marker for trisomy Genetics Edwards syndrome is a chromosomal abnormality characterized by the presence of an extra copy of genetic material on the 18th chromosome, either in whole (trisomy 18) or in part (such as due to translocations). The additional chromosome usually occurs beforeconception. The effects of the extra copy vary greatly, depending on the extent of the extra copy, genetic history, and chance. Edwards syndrome occurs in all human populations but is more prevalent in female offspring.[7] A healthy egg and/or sperm cell contains individual chromosomes, each of which contributes to the 23 pairs of chromosomes needed to form a normal cell with a typical human karyotype of 46 chromosomes. Numerical errors can arise at either of the two meiotic divisions and cause the failure of a chromosome to segregate into the daughter cells (nondisjunction). This results in an extra chromosome, making the haploid number 24 rather than 23. Fertilization of eggs or insemination by sperm that contain an extra chromosome results in trisomy, or three copies of a chromosome rather than two.[8] Trisomy 18 (47,XX,+18) is caused by a meiotic nondisjunction event. With nondisjunction, a gamete (i.e., a sperm or egg cell) is produced with an extra copy of chromosome 18; the gamete thus has 24 chromosomes. When combined with a normal gamete from the other parent, the embryo has 47 chromosomes, with three copies of chromosome 18. with edwards syndrome Isodicentric 15, also called idic(15), partial tetrasomy 15q, or inverted duplication 15 (inv dup 15), is a chromosome abnormalityin which a child is born with extra genetic material from chromosome 15. People with idic(15) are typically born with 47 chromosomes in their body cells, instead of the normal 46. The extra chromosome is made up of a piece of chromosome 15 that has been duplicated end-to-end like a mirror image. It is the presence of this extra genetic material that is thought to account for the symptoms seen in some people with idic(15). Individuals with idic(15) have a total of four copies of this chromosome 15 region instead of the usual two copies (1 copy each on the maternal and paternal chromosomes). The extra chromosome is rarely found in mosaic state, i.e. some of the cells carry the marker chromosome. However, mostly because of the marker’s instability and tendency to be lost during cell division (mitosis), some cells are completely normal with 46 chromosomes. Occasionally, cells may have more than one idic(15), resulting in 48 or 49 chromosomes in all or some of their cells. A similar clinical picture albeit to a milder degree could be expected in individuals that have the extra chromosome 15 material as an interstitial duplication; not as a marker chromosome; thus having 46 chromosomes.[1][2] Signs and symptoms Individuals with idic(15) have delays in language development and motor skills such as walking or sitting up. Other traits may include low muscle tone (hypotonia), seizures, short stature, and mental retardation. Distinctive facial features associated with idic(15) may include epicanthal folds (skin folds at the inner corners of the eyes), a flattened nasal bridge, button nose, and a high arched palate (roof of the mouth). Some individuals with idic(15) also have features of autism, such as problems with communication, social interactions, and repetitive and stereotyped behaviors (e.g., lining up toys, playing with a toy in the same manner over and over again, hand flapping, rocking back and forth). These are some mild features but with a severe person there may be more such as inability to talk at all. Genetics Generally, idic(15) is not inherited; it is said to appear de novo; in one member of the family, by chance. In most cases, the abnormal chromosome is generated in the mother’s germ cells; oocytes. This finding is due to ascertainment bias; i.e. cases with maternally derived idic(15) usually have clinical findings and attract attention but those with paternally derived idic(15) usually do not. Thus, established cases are usually patients with maternally inherited idic (15).[4] . The smallest markers appear to be harmless and they may go undetected. However, if they are large enough to contain a number of important genes, they may result in â€Å"idic(15) syndrome† which is characterized by mental retardation, autism and other neurological symptoms.[5] One of the regions responsible for the symptoms of idic(15)syndrome is the critical PWS/AS-region named after the Prader-Willi and/or Angelman syndromes. Jacobsen Syndrome, also known as 11q deletion disorder, is a rare congenital disorder resulting from deletion of a terminal region of chromosome 11 that includes band 11q24.1. It can cause intellectual disabilities, a distinctive facial appearance, and a variety of physical problems including heart defects and a bleeding disorder. The syndrome was first identified by Danish physician Petra Jacobsen,[1] and is believed to occur in approximately 1 out of every 100,000 births. Possible characteristics * Heart defects * Mild to severe intellectual disabilities * Low-platelets (thrombocytopenia) * Facial/skeletal (dysplasia) * Wide-set eyes caused by trigonocephaly * Folding of the skin near the eye (epicanthus) * Short, upturned nose (anteverted nostrils) * Thin lips that curve inward * Displaced receding chin (retrognathia) * Low-set, misshapen ears * Permanent upward curvature of the pinkie and ring fingers (camptodactyly) * Large great toes/Hammer toes Klinefelter’s syndrome, 47, XXY, or XXY syndrome is a condition in which a human has an extra X chromosome. While females have an XX chromosomal makeup, and males an XY, affected individuals have at least two X chromosomes and at least one Y chromosome.[1] Because of the extra chromosome, individuals with the condition are usually referred to as â€Å"XXY Males†, or â€Å"47, XXY Males†.[2] This chromosome constitution (karyotype) exists in roughly between 1:500 to 1:1000 live male births[3][4] but many of these people may not show symptoms. The physical traits of the syndrome become more apparent after the onset of puberty, if at all.[5] In humans, 47,XXY is the most common sex chromosome aneuploidy in males[6] and the second most common condition caused by the presence of extra chromosomes. Other mammals also have the XXY syndrome, including mice. Patau syndrome, also known as trisomy 13 and trisomy D, is a chromosomalabnormality, a syndrome in which a patient has an additional chromosome 13 due to anondisjunction of chromosomes during meiosis. Some are caused by Robertsonian translocations, while others are caused by mosaic Patau syndrome. The extra chromosome 13 disrupts the normal course of development, causing heart and kidney defects, amongst other features characteristic of Patau syndrome.[vague] Like allnondisjunction conditions (such as Down syndrome and Edwards syndrome), the risk of this syndrome in the offspring increases with maternal age at pregnancy, with about 31 years being the average.[1] Patau syndrome affects somewhere between 1 in 10,000 and 1 in 21,700 live births.

Location Decision and Sustainability Essay

In this paper we are going to give an in-depth perspective on the subjects of location decision, clusters and corporate social responsibility. First, we will address the location decision subject. Second, we will discuss clusters and different cluster types. Last, we will review the corporate social responsibility subject. After giving an in-depth perspective on the three subjects, we will discuss the relationship between these different topics. Location Decision Location decision is an important strategic decision that must be considered by a firm. It is important because the location strategy could affect the ability of the firm to reach it consumer, to produce in economic scale, or even to get access to the resource they needs. Location decision could also be able to give the firm a competitive advantage, because of transfer of knowledge, innovation, specialisation, and complementariness. In choosing a country, there are two main dimensions that usually be considered. Those two main dimensions are country competitiveness and also risk of the country. The country competitiveness usually is divided into two main categories, which are the market competitiveness and also the industry competitiveness. A firm should able to assess those categories to find out in which location or in which country they should operate to maximize their opportunity and profits and minimize their risks and costs. Country Opportunity Assessing the market opportunity for a country means that we assessing the potential demand that available in a country. The variables that take into account for this assessment are the growth of the market, the size of the market, and also the quality of the demand that exist on the market in a certain country. This market assessment will define whether it is worth or not to start a business in that country, will the firm have a good demand or not, and will that demand able to generate profit for the firm or not. Looking some macroeconomics indicators can assess the market opportunity. Those indicators can be the GDP, GDP per capita, and income distribution, etc. ooking to those indicators can give us an insight about the market size of the country or country buying power compared to another country, etc. the quality of demand is describing the segmentation of the countries. Generally countries are grouped into 4 main clusters: †¢Developing countries, low income per capita, and low growth †¢Emerging countries, relatively low income per capita but high in growth †¢The newly industrialized economies, high growth and moderate to high wealth †¢The final cluster, low growth and high wealth, usually these countries have already reached their ‘maturity’. The other important opportunity that needs to be considered is the industry opportunities. The industry opportunity is including a broad part of aspects. Those aspects are the resource (including human resource and natural resource), the infrastructures, and also government policies (such as government incentive to enhance foreign investment, or tax reduction). A company needs to consider the human resource issue. It is usually addressing the quality of the labor in a country. It is also considering the minimum wages or average wages of labor in a country. That issue is an important issue because it will affect the production cost and production process. The natural resource issue usually also become some major strategic issue because it enables the firm to get closer to the input that they needs including strategic geographical location that can benefits their mobility. Country Risks Beside the opportunities, a firm should also consider the risks of the country. There are some major risks that need to be considered. Political risk, this risk have a high relation with the government policies and political condition in each country. A country with an unstable politic environment may have higher risk of rioting or policy changed. It can cause disadvantage for the firm such as vandalism to firm’s assets, or difficulties from the bureaucracy. Economic risk, this economic risk is including the inflation rate, economic growth, exchange rates of the currency, and also the variability. A firm needs to consider it carefully because it surely will affect the company stability and profitability. Competitive risk, this risk refers to the risk that company gets from the competition, the business group, cartels, or even the competitive advantage among product that being sold in the company. Operational risk, this risk is covering the risks from infrastructures, supplier policy, or even government regulation such as taxation, and nationalistic preference. Location Strategy After knowing the opportunity and the risks that exist in a country. A company should use that data to forming their strategy. The firm needs to compare a list of country to know which country that is the best for their investment, considering the risk and the opportunity of each of them. Clusters In this section of the paper we are going to discuss clusters. In order to explain what clusters are, we will use the definition given to clusters by Michael Porter (1990), which he used for his study of clusters. â€Å"clusters are geographic concentrations of interconnected companies, specialized suppliers, service providers, firms in related industries, and associated institutions in a particular field that compete but also cooperate†. There are many different types of clusters, which we will discuss below. However, we are going to start by explaining how and why corporations form clusters. Usually for clusters to arise there are already certain resources and capabilities available in a certain area, which are important for the industry and thus the cluster that is formed there. Next, there need to be several corporations that see the advantages of joining and creating a cluster. This is necessary so the different corporations can work together to improve their cluster and add value to it. This will attract new players for it, who can add even extra value to the created cluster. As this process continues, more players tent to join the cluster because it becomes more important every time for the general industry on which the cluster is based, but also because a lot of knowledge and resources are generated within the cluster on which a corporation not joining it, would miss out. Besides generating a lot of knowledge and industry advantages, clusters also improve the general competitiveness of a certain area. Moreover, they can significantly boost the economy of the area were the cluster is situated as many employment opportunities are created alongside the expansion of the cluster. According to the research of Lundequist and Power (2002) four types of clusters exist. These are the industry-led initiatives, the top-down cluster-branding exercises, the visionary projects and temporal clusters. We will discuss each type separately below. The industry-led initiatives are clusters that depend greatly on involving the public sector into the cluster. Moreover, they are the key importance of regional economic growth in their area and they can even bring national economic growth. The second cluster type is the top-down cluster-branding exercises. This type does not have the industry as its key building block but instead builds on the public sector. Also, this type does not find the creation of the clusters itself very important, but focuses on the creation of a brand name first. The third cluster type is the visionary cluster. As the name says, this cluster builds on one strong vision and it therefore needs good leadership in order to execute this vision. Thus, this type needs ‘cluster motors’ (Lundequist and Power, 2002) which are firms that can really start up the cluster and keep it going. In order to sustain this cluster there needs to be a good task division in terms of responsibilities and tasks. This all needs to be supported by a good and strong network and environment. The last cluster type is the temporal cluster and is usually build up around natural resources and physical conditions. Noteworthy is that this type can even be climate-driven and seasonal, meaning that the cluster does not always exist outside certain seasons for example. Lundequist and Power (2002) mention some similarities in all these types of clusters and they are worth mentioning quickly. First, all types work best when there are multiple players with a large interest in the cluster. Moreover, it is important that a clear vision is present for it. Above we mentioned the ‘cluster motors’ which is especially important with regard to the visionary cluster, but all types benefit greatly if such motors are present. Second, it is important if every corporation has a clear view of what they add to the cluster. Thus, good management should be present to support this. Third, it was mentioned explicitly for the second cluster type, but again all types benefit from brand building and thus attention should be paid to marketing this. Last, the progress made within the clusters is very important and appropriate policies and strategies should be present to support this. To conclude, not all cluster types fit exactly in the definition given at the beginning of this part but all have proven to be successful initiatives (Lundequist and Power, 2002). However next to Porter also Eden (2002) and Markusen (1996) identified a cluster typology. According to Eden a cluster could be horizontal (specialized) or vertical (complementary). However it must be said that Eden actually identifies the cluster characteristics than cluster types. Markusen on the other hand identifies the type of clusters by the geographic area, the type of clusters are formed within a metropolitan area. The four types she identifies are Marshallian Industrial Districts and Subdistricts, Hub and Spoke Industrial Districts, Satellite Platform Districts and State Anchored Industrial Districts. The typology in her case is derived from the geographic, public or private investment decisions, the availability of labor, and amount of trade within and outside the district. It is said that there are several similarities between Markusen and Porter’s work. (Fraizer and Zelbst, 2010) Corporate Social Responsibility Affected by the globalization and thus growing importance and awareness of ethics and human rights, as well as being environmentally, socially and economically responsible, internationally operating corporations have to deal with a lot more issues than several years ago. This area of growing importance is called â€Å"Corporate Social Responsibility† (CSR) and will be explained as follows: In the past decades most of the corporations did not care about issues like sustainable development, business ethics, human rights or global citizenship, instead only focused on making as much financial profit as they can, however they could achieve it. But over the last several years the number of natural disasters and the increasing warming of the planet have made the people more aware of issues such as sustainable development and allocation of resources. Furthermore the globalization and advanced technologies such as the World Wide Web make the markets and the operations of internationally operating corporations much more transparent to all parties concerned. This is why consumer have also started to base their buying-decision on issues such as human rights, business ethics and sustainable development and take into account if a company does well in the field of â€Å"Corporate Social Responsibility† or not. Moreover, laws and public initiatives put a lot more pressure on corporations to improve ethical and sustainable actions in the regions they are operating in. As a consequence, companies started to consider these aspects more seriously than before and tried to implement such topics in their strategic activities. To combine ethical, environmental and social aspects with economic aspects is a challenge and one of the most difficult strategic issues corporations have to deal with. Nowadays, corporations are ade feel responsible for the regions they are operating in, as well as for the people who are working for them. Because of that, â€Å"Corporate Social Responsibility† has become one of the core strategic issues of them to maintain a good image, which is finally responsible for their financial results. By investing in their employees, in infrastructure of the region they are operating in and in acting natural friendly or investing in sustainable energy, corporations not only generate a greater image of them and help the public, they also make finally profit out of it. Because of that, we can say that it is a â€Å"win-win situation† for both. Customers are being strongly influenced by such issues, because they sensitively recognize the â€Å"Corporate Social Responsibility† performance of a corporation. When a company does well in this field, the customer is finally willing to buy its product or to keep on buying its product, because he or she feels comfortable investing in a company who helps the public and treats its employees very well. This finally results in better revenues, which is a financial parameter. Furthermore employees are feeling much more comfortable and thus work more efficient, when the corporation gives them the feeling of feeling important and investing in them. Higher Efficiency finally results in better products, which affects the buying-decision of the customer, again. Moreover business partner and suppliers are more willing to cooperate with a corporation, who has a good image and who treats them fairly. By cooperating with good business partner and suppliers the corporation ensures good quality of its products, which finally results in better products and thus greater customer-satisfaction, again. So we can see that there is a strong correlation between the financial performance of a corporation and its social performance, which we also know as â€Å"Corporate Social Responsibility†. Additionally, according to Kanji and Chopra (2010) these are the six dimensions in CSR that are most important for companies, they are (1) Organizational Strategic Planning Systems, (2) Social accountability and Social Investment, (3) Environment Protection and sustainability, (4) Corporate Governance and Economic Responsibility, (5) Ethics and Human Resources, and (6) Corporate Social Responsibility Index. Furthermore, there are more advantages of â€Å"Corporate Social Responsibility† than the financial one, which we can see while looking at the business relations, mentioned above. Although, â€Å"Corporate Social Responsibility† has become much more important over the last years, it is still a field, which has to be more researched about, when we refer to the number of articles already published. The less number of articles published in this field could be related to its definitions, which are very broaden and sometimes difficult to express, because of large number of issues involved. To sum it up, because of the growing awareness of ethical, social and sustainable activities of corporations the field of â€Å"Corporate Social Responsibility† has become a core strategic activity of corporations and for some even a source of competitive advantage. Location decision, clusters and CSR in relationship. As one can already notice when reading the in-depth perspectives above, there are some common grounds for the three topics. When one forms a cluster it will likely increase the country opportunity by specifically creating very attractive industry opportunities. As the cluster generates knowledge, resources, and capabilities attractive for some specific firms. Moreover, they create the necessary infrastructure and often the right political climate is thus present. Often this contributes to better economic circumstances in that area or region, increasing the market opportunities. Market opportunities are strongly connected to corporate social responsibility. Often industrialized countries demand more corporate social responsibility of a firm than a developing country does. Again this whole process influences the location decision that a company has to make and the market attractiveness for a firm.

Using a Focus Word to Help With Pronunciation

Pronunciation can be improved by focusing on the right words. Knowing the difference between content words and function words is the first step. Remember that we stress content words in English as they provide the words that are most important to understanding a sentence. In other words, function words like the prepositions  at, from, or to are not stressed, whereas content words such as the nouns city or investment and main verbs like study or develop are stressed because they are key to understanding. Step 1: Find the Focus Word Once you are familiar with using content words to help with stress and intonation, its time to take it to the next level by choosing a focus word. The focus word (or words in some cases) is the most important word in a sentence. For example: Why didnt you telephone?  I waited all day! In these two sentences, the word telephone is the central focus. Its the key to understanding both sentences. Someone might answer this question by saying: I didnt telephone because I was so busy.   In this case, busy would be the focus word as it provides the main explanation for someone being late. When saying the focus word, its common to stress this word more than the other content words. This may include raising the voice  or speaking the word louder to add emphasis. Step 2: Change Focus Words to Move the Conversation Along Focus words may change as you move through a conversation. Its common to choose focus words that provide the next topic for discussion. Take a look at this short conversation, notice how the focus word (marked in  bold)  changes to move the conversation forward. Bob: Were flying to Las Vegas next week.Alice: Why are you going there?Bob: Im going to win a fortune!Alice: You need to get real. Nobody wins a fortune in Las Vegas.Bob: Thats not true. Jack won a fortune there last year.Alice: No, Jack got married. He didnt win a fortune.Bob: Thats what I call winning a fortune. I dont need to gamble to win a fortune.Alice: Looking for love in Las Vegas is definitely not the answer.Bob: OK. What is the answer in your opinion?Alice: I think you need to start dating girls from here.Bob: Dont get me started on girls from here. Theyre all out of my league!Alice: Come on Bob, youre a nice guy. You will find someone.Bob: I hope so... Stressing these key words helps change the topic from a vacation in Las Vegas  to finding someone to marry to solving Bobs love life issues.   Practice: Choose the Focus Word Now its up to you to choose the focus word. Choose the focus word for each sentence or group of short sentences. Next, practice speaking these sentences while making sure to emphasize the stress word more.   What do you want to do this afternoon? Im bored!Why didnt you tell me she had a birthday?Im hungry. Lets get some lunch.Nobodys here. Where has everyone gone?I think Tom should buy lunch. I bought lunch last week.Are you going to finish work or waste time?You always complain about work. I think you need to stop.Lets get Italian food. Im tired of Chinese food.The students are getting horrible grades. Whats wrong?Our class is going to have a test on Friday. Make sure you prepare. The focus word for most of these should be clear. However, remember that its possible to change the focus word in order to bring out different meanings. Another good way to practice is to use sound scripting — the marking up of your text — to help you practice dialogues.