Hemoglobinopathy for Malaria Protection

Hemoglobinopathy for Malaria Protection Redcells and  anaemia:  What  evidence exists to  support  the hypothesis that  haemoglobinopathies confer protection against  malaria? Introduction Haemoglobinopathies can be divided into two areas, abnormal haemoglobin synthesis and decreased haemoglobin synthesis. Abnormal haemoglobin synthesis is usually a result of genetic defects, caused by amino acid substitutions in the ÃŽÂ ± or ÃŽÂ ² chains of the haemoglobin molecule. Decreased haemoglobin synthesis is also caused by genetic disorders and arise from gene deletions of either ÃŽÂ ± or ÃŽÂ ² globin chains. This group of diseases is called thalassemia. Malaria is a parasite infection caused by the Plasmodium genus. There are 4 types that affect humans, Plasmodium falciparum (P. falciparam), Plasmodium vivax (P. vivax), Plasmodium malariae (P. malariae) and Plasmodium ovale (P. ovale). The most common form is P. falciparam, which is responsible for 80% of all cases and 90% of deaths. Malaria affects between 300-500 million people each year and is prevalent in tropical areas where mosquitoes act as vectors for the parasite. Hence, much of research undertaken to date focuses primarily on P. falciparam infection. Upon entering the body the Plasmodium parasite migrates to the liver. After multiplication, they are released into the blood as merozoites. The merozoites then bind to and enter the red blood cell. The hypothesis that haemoglobin disorders confer protection against malaria can be evaluated by reviewing the evidence in support of malarial protection. However, evidence showing that these disorders do not confer protection should not be ignored. Sickle cell disease The protective effect of Sickle cell disease (SCD) against malaria was first described over 60 years ago (Beet, 1946). SCD is an inherited disease, caused by the production of abnormal haemoglobin, HbS. The gene for sickle haemoglobin (HbS) substitutes valine for glutamic acid at the sixth position from the amino terminus of the ÃŽÂ ² chain (Serjeant). Under low oxygen tension, the HbS polymerises resulting in sickling of the red blood cell (haem mal 4). Homozygous individuals for HbS carry the genotype HbSS, inheriting abnormal genes for ÃŽÂ ²-globin from both parents. Without adequate treatment, this form of the disease is fatal in early life. However, heterozygous individuals who inherit one abnormal and one normal ÃŽÂ ²-globin gene are asymptomatic and carry the genotype HbAS. This genotype is known as Sickle cell trait, which various studies claim confers protection against malaria (Allison, 1964, Freidman, 1978) ( ref 1011, haem mal4). The mechanism by which HbAS prevents malaria is unclear and is an area that requires greater research. However, there have been many suggested mechanisms over the years. These mechanisms involve the interactions between red blood cells and parasites, without excluding the role of the immune system. A study conducted by Cholera 2008 examined the role of cytoadherence of parasite and red blood cells. The findings showed that parasite infected HbAS red blood cells showed reduced binding capability to endothelial cells and blood monocytes when compared to parasitized normal Hb red blood cells. This impairment caused by HbAS is caused by a reduced expression of P. falciparam erythrocyte membrane protein 1 (PfEMP1), responsible for cytoadherence of infected red blood cells to critical tissues such as the brain. The role of the immune system in resisting parasite infection has also been explored. Increased phagocytosis of infected HbAS erythrocytes in comparison with normal infected erythrocytes was observed ( ref smith et al 2002, akide et al 2003, Roberts Williams 2003 etc Haem mal). Further evidence showing the central role of the immune system has been illustrated by increased protection with age, strengthening the importance of immunological responses to parasite infection. Other mechanisms include the inhibition of parasite growth within erythrocytes by HbS polymerisation caused by low oxygen tension ( Haem mal). Haemoglobin C Haemoglobin C is found in west Africa, and in its homozygous state, referred to as HbCC, causes haemolysis and splenomegaly. Heterozygotes are asymptomatic and display the genotype HbAC. Haemoglobin C arises from a point mutation where glutamate is replaced by lysine at the sixth position of the ÃŽÂ ²-globin chain.   Acquired immunity against P. falciparum was reported in HbC and HbS due to abnormal display of PfEMP1 (Verra et al, 2007). However, studies on HbC malarial protection have produced contradictory results. Some studies claimed homozygous HbCC individuals were protected from developing severe malaria(haem mal) and were also at a reduced risk of malarial infections (modiano et al, 2001, haem mal). ÃŽÂ ±-Thalassemia ÃŽÂ ±-thalassemia is caused by decreased synthesis of ÃŽÂ ±-globin. It is caused by deletion of ÃŽÂ ±-globin genes on chromosome 16 (Yuthavong Wilairat 1993, haem mal). ÃŽÂ ±-thalassemia results in mild anaemia, and lower levels of haemoglobin in red blood cells. Population genetics have shown ÃŽÂ ±-thalassemia to protect against malaria, but similar to SCD, there is no consensus on the mechanism of action. Studies have shown ÃŽÂ ±-thalassemia protects against severe and fatal malaria, whereas parasiteamia is unaffected (72-78, haem mal 3). A reduction in complement receptor 1 (CR1) expression caused by ÃŽÂ ±-thalassemia has been proposed as a possible mechanism of protection. CR1   deficient erythrocytes reduce rosetting of cells, which is associated with severe malaria ( Cockburn 2004). This rosetting of cells mediated by CR1 can potentially obstruct capillaries (Stoute, 2011). ÃŽÂ ²-Thalassemia ÃŽÂ ²-thalassemia results in either no or little ÃŽÂ ²-globin production, caused by mutations on chromosome 11. Heterozygotes experience mild anaemia and ineffective erythropoiesis whereas homozygotes suffer from severe anaemia and leads to death without proper treatment (Weatherall,2000, haem mal). Protection in early life from malaria was seen in ÃŽÂ ²-thalassemia carriers as a result of foetal haemoglobin levels declining more slowly than usual ( Pasvol 1978). Other researchers reported P. falciparam growth inhibition in vitro (Brockleman 1978) and higher phagocytosis of ÃŽÂ ²-thalassemia infected erythrocytes compared to normal erythrocytes. Like ÃŽÂ ±-thalassemia and SCD, there is not yet a definitive mechanism by which ÃŽÂ ²-thalassemia protects against malaria and suggested mechanisms put forward until now require greater research. Conclusion By examining the evidence, haemoglobinopathies do confer protection against malaria. However, the protection varies from one disorder to the next as does the level of protection from malarial infection and parasite progression. The protection revolves around the red blood cell which is central to the life cycle of the malaria parasite. The different haemoglobin abnormalities disrupt parasite and red blood cell interactions in diverse pathways, resulting in differing mechanisms of protection and subsequently different levels of protection. The lack of consensus regarding mechanisms involved highlights the necessity for further research. In addition to the possible protection pathways mentioned earlier, the analysis of population genetics cannot be ignored. The haemoglobinopathies discussed have a higher prevalence in malaria endemic regions due to the protection conferred from this lethal parasite.

Catcher in The Rye Essay -- essays research papers

Catcher in the Rye   Ã‚  Ã‚  Ã‚  Ã‚  J.D Salinger’s novel â€Å"Catcher in the Rye,† focuses mainly on Holden Caulfield because he is the narrator and the novel is about his memory of characters and events throughout the story. These characters are more than just remembrances but actually help the reader to better understand Holden. Mr. Antolini, Phoebe, and Jane Gallagher are all characters that help fully characterize Holden.   Ã‚  Ã‚  Ã‚  Ã‚  Mr. Antolini helps the reader better understand Holden’s hasty judgments about characters in the novel. He is one of the few people in the novel who Holden respects and does not consider a â€Å"phony.† Holden respects Mr. Antolini because he understands him and does not treat him like an inferior student like the rest of his teachers do. Mr. Antolini is very open with Holden and this is shown when he lets him stay the night in his apartment. Holden’s quick judgments of people are shown and better understood when Mr. Antolini touches his forehead while he sleeps in chapter 24. â€Å"I know more damn perverts, at schools and all, than anybody you ever met, and they’re always being perverty when I’m around.†(192) Holden jumps to conclusions right away when he wakes up to Mr. Antolini touching his forehead. Instead of thinking that his teacher was just showing affection and care for a student he is very quick to think that he is a pervert and homosexual. In the quote Holden says, â€Å"they’re always being perverty when I’m around,† this is more evidence that Holden jumps to conclusions and is quick with assumptions rather than to think about what it is to be a pervert. He thinks that he is just in the wrong place at the wrong time but it is more likely that he just assumes they are being â€Å"perverty† when they are truly not. Another example of Holden being quick with judgment is directly after the incident happens. Without letting the incident sink in, Holden changes into his clothes and runs out of the apartment. Mr. Antolini and the events that take place in his apartment help the reader fully understand Holden. Mr. Antolini is a compassionate person and his actions are out of care for his friend and student, Holden’s quick and hasty judgment is shown when he overlooks Mr. Antolini’s concern and affection for a homosexual advance.   Ã‚  Ã‚  Ã‚  Ã‚  Phoebe is another character that helps the reader bet... ...y voice was shaking something awful.† Holden’s helplessness to realize that sex can be casual is showing that he is immature and that he doesn’t want to let go of his childhood innocence. Jane’s character, a girl who Holden knows very well and has affection for, has casual sex which makes Holden very upset, this helps the reader better understand Holden’s immatureness and his refusal to let go of his childhood innocence.   Ã‚  Ã‚  Ã‚  Ã‚  In the novel â€Å"Catcher in the Rye† the reader is able to better understand Holden by the characters in his remembrances. Mr. Antolini, a person who shows affection for Holden, shows the reader that Holden makes quick assumptions and judgments with characters in the novel. Phoebe, Holden’s younger sister, makes it evident to the reader that Holden does not want to grow up, mature, and have a future as an adult. Jane Gallagher’s character also helps the reader better understand Holden by making it evident that he does not want to let go of his childhood innocence. Although Holden’s character is the main focus of the novel, his remembrances of other key characters help define him and give the reader a better understanding of who he is.

Online Hotel reservation Essay

INTRODUCTION Over the years, the internet has greatly changed the way people use computers and communicate today. Many Internet terms have become part of people’s everyday language and e-mail has added a whole new means through which people can communicate. By the turn of the century, information, including access to the Internet, will be the basis for personal, economic, and political advancement. The popular name for the Internet is the information superhighway. Whether you want to find the latest financial news, browse through library catalogs, exchange information with colleagues, or join in a lively political debate, the Internet is the tool that will take you beyond telephones, faxes, and isolated computers to a burgeoning networked information frontier. The pace of change brought about by new technologies has had a significant effect on the way people live and work worldwide. New and emerging technologies challenge the traditional process of teaching and learning, and the way education is managed. Information technology, while an important area of study in its own right, is having a major impact across all curriculum areas. As internet technology has improved, so have online reservation systems. Today, it is possible through online, to make a reservation for a hotel anywhere in the world. Hotels can create Web site and post new content on it every day. Technology has gone a long way, improving the lives of people. These technological breakthroughs have lots to offer, making great things in the easiest, fastest and efficient possible ways you can think of. Online hotel Reservation is very useful for the people especially for socials that they can now easily reserve a room in a hotel through online Internet. Easy worldwide communication provides instant access to a vast array of data. Project Overview Project Statement The hotel reservation system will provide service to on-line customers, travel agents, and an administrator. On-line customers and travel agents can make searches, reservations and cancel an existing reservation on the hotel reservation’s web site. Administrator can add/update the hotel and the room information approve/disapprove a new travel agent’s account application and  generate a monthly occupancy rate report for each hotel. Literature review The design of travel and tourism websites has received substantial attention by scholars (e.g.Schegg et al., 2002; Law and Leung, 2002; Law andWong, 2003; Scharl, Wà ¶ber and Bauer, 2003; Landvogt, 2004; So and Morrison, 2004; Essawy, 2005; Jeong et al., 2005; Law and Hsu,2006;Zafiropoulos and Vrana, 2006; Schmidt, Cantallops, and dos Santos, 2007).Landvogt (2004) evaluates several online booking engines over 23 differentcriteria, like overall user friendliness, payment method, instant confirmation,reliability, and invoicing function among others. These criteria present some ofsystem’s functions and design principles discussed furtherin current paper.In their study Jeong et al. (2005) find that only two characteristics ofhotel websites (information completeness and ease of use) are importantdeterminants of perceived website quality. These results are bewildering asmost studies identify more dimensions of perceived service quality to besignificant for website users. Law and Hsu (2006), for example, assess thedimensions of hotel websites (information regarding the reservation, hotelfacilities, contact details of the property, surrounding area and websitemanagement) and attributes in each dimension mostly valued by online users.Some of the most important website attributes are found to be the room rates,availability and security of payments (in the reservation informationdimension), the location maps, hotel and room amenities (in facilitiesinformation), telephone, address and e-mail of the hotel (for contactinformation), transportation to the hotel, airports and sights (for surroundingarea information), and up-to-date information, multilingual site and shortdownload time (for website management). So and Morrison (2004) applysimilar criteria for website evaluation as the preceding study but they groupthem into technical, marketing, consumer perspective and destinationinformation perspective criteria.Essawy (2005) focuses on website usability and shows that severeusability problems with interface quality, information quality, and servicequality affect negatively the purchase and revisit intentions of website users.The author identifies some of the practical tools/activities for increasing users’perceived satisfaction, purchase intention, and potential relationship building –exchanging links  with local points of interest, shorter/simpler pathways toleisure breaks, greater depth of information for room facilities and pricing,providing proactive interactions, and avoiding third-party reservation systems. In similar vein, Scharl, Wà ¶ber and Bauer (2003) assess the effectiveness ofhotel websites. Authors identify personal, system and media factors thatcontribute to hotel website adoption. In the system factors group, that is morecontrollable by the hotel management compared to personal and media factors,they identify the perceived utility of the product, speed of the system,intelligence, layout, services, languages, navigation, interactivity, reliability ofthe system.Research has also shown that trust is an important dimension of websitedevelopment (Fam, Foscht and Collins, 2004; Chen, 2006; Wu and Chang, 2006). If consumers do not trust the website they will not visit it, or will nottransform their visits into real purchases.Although much effort has been put towards evaluating the design oftourism websites and the identification of website attributes highly valued bycustomers, there is a gap in the research in the OHRS design and its specificproblems have not received enough attention in previous research with fewnotable exceptions. In series of reports Bainbridge (2002, 2003a, 2003b)discusses the practical aspects of the OHRS design (the search option in thesystems, the booking process and the date format), while Ivanov (2002, 2005)discusses the types and main characteristics of OHRSs and the major marketingdecisions to be taken by the marketing managers in their design. The review of available literature on the tourism / hotel website and OHRS design reveals the following conclusions:  · Website users are interested in easy navigation through the system.  · They want abundance of information for the services offered in textand pictures.  · Trust is vital for the usage of the system.  · Website design can significantly influence the online experience of theusers and their purchase intentions.  · Website design itself does not guarantee online purchases but it is theperceived utility of the product that attracts customers. Demographic characteristics and Internet Usage Behaviour Education level, age, income,and occupation have been found to be significantly different among Internet users. Bonn etal.(1998)[15] study showed that those who use the Internet as a travel information-gathering tool are likely to bemore educated, younger, with higher household incomes, use commercial lodging accommodations while traveling, tend to travel by air and spend more money on travel-related expenses. Weber and Roehl’s (1999)[16] study shows similar results. They found that online travel purchasers are more likely to be people who are aged 26-55, with higherincomes, with higher status occupations, and have more years of experience with the Internet than those who do not search or purchase online. The Asian demographic patterns of online purchasers tend to mirror their Western profiles. According tostudies carried out by Technowledge Asia in 1999 and 2000, cybershoppers in the four Asian regions (Singapore, Hong Kong, Taiwan and Malaysia) were found to be mainly males, in the age group of 26 to 35 years and better educated. Hence, it has been shown that an individual’s educational level may affect their susceptibility to attitude change. Intelligent people understandcomplex messages better, and as a result, persuasion by complex messages is more likely. In addition, an individual’s educational level is alsopartially a measure of their socioeconomic status. Weber and Roehl (1999)[16] study found that Internet â€Å"bookers† were more likely to have used the Internet for 4 years. Other researchers confirmed that Internet bookers spend more time online per week than those booking offline (Weber and Roehl ,1999)[16]. Finally, the intention to shop online is also influenced by consumers’ Internet shopping history (Shim et al., 2001)[17]. It is demonstrated by pastresearch findings that prior online shoppingexperiences have a direct impact on Internet shopping intentions (Weber and Roehl, 1999)[16]. There have been other studies that have supported online experience or tenure as key determinant of onlinebuying behavior (Bellman, Lohse, and Johnson, 1999[18] and Beldona et al, 2004)[19]. Findings indicate that the greater the number of years the user spent online combined with higher frequency of Internet usage; the greater was the likelihood of buying (Bellman et al., 1999[18]; Weber and Roehl, 1999[16] and Beldona et al 2004)[19]. Alwitt and Hamer (2000)[20] posit that consumers increase  their control with more time spent on the Internet, and in turn develop finer expectations of their interactions with businesses in general. Hammond, McWilliam, and Diaz (1998)[21] of users’ attitudes towards the Web. Based from the literature review of the Internet users,it is noticeable that Internet users are better educated, higher incomes, higher status occupations, have more online experience, use commercial lodging accommodations while travelling and tend to travel by air. In Malaysia, one of the profiles that had an early exposure to the culture of using the Internetfor personal and professional reasons was university residents. These may consist of students, administrators and lecturers. However, university staffs are more likely to fit the profiles of the Internet users (in terms of purchasing) due to their financial capability and mobility. Consequently, this leads to: H1 : There is a relationship between the university   staffs’ demographic factors and the determinants of  online hotel reservation H2 : There is a relationship between the university   staffs’ Internet usage behavior and the determinants of online hotel reservation

sociology internationalist crime deviance - 1200 Words

1c How do interactionists explain crime? (Labelling Theory) Are offenders different? Interactionists argue that a mistake most perspectives make is that they assume lawbreakers are somehow different from law-abiding people. The labelling theory suggests that most people commit deviant and criminal acts but only come are caught and stigmatised for it. It is for this reason that emphasis should be on understanding the reaction and definition of deviance rather than the causes of the initial act. Quote by Howard Becker 1963 â€Å"Deviancy is not a quality of the act a person commits but rather a consequence of the application by others of rules and sanctions to an ‘offender’. Deviant behaviour is behaviour that people so label.† The†¦show more content†¦This concept refers to the processes involved in labelling and then whether or not a person takes on the self-image of the ‘deviant’. Creating Rules Once labelling theorists began the process of looking at how social life was open to negotiation and that rule enforcement was no different than other social activities, their attention shifted to the creation of rules and laws and why they were made. Traditionally sociologists took a Marxists view that they were made in the interest or the ruling class, or they took a more functionalist view that laws in a democracy were a reflection of the views of the majority of the population. Becker doubted both these accounts and argued instead that: â€Å"Rules are the products of someone’s initiative and we can think of the people who exhibit such enterprises as ‘moral entrepreneurs’.† So labelling theorists argue that laws are a reflection of the activities of people (moral entrepreneurs) who actively seek to create and enforce laws. The reasons for this are either that the new laws will benefit the activists directly or that the activists believe that the laws are truly beneficial to society. Becker’s most famous example of this is his study following the outlawing of cannabis in the USA in 1937. Becker as well as other sociologists use term ‘moral crusade’ to describe the movements/actions taken to pass laws. Criticisms The idea that those who seek to pass laws or impose rule upon others have been largelyShow MoreRelatedCity of God949 Words   |  4 PagesLaura Schneider Sociology 1 The City of God After watching â€Å"The City of God†, I personally can see the correlation that crime plays in association with poverty, social influence, and lack of law and order. Though my perspective vastly varies from that of sociological theorists, I think we can both conclude that this movie is an extreme representation as to what can occur when society shuns away disadvantaged youths to a place that lacks justice as well as ethical and moral responsibilities.Read MoreDeviance Theory and Drug Use1619 Words   |  7 PagesTheories of Deviance Applied to Drug Use Since the dawn of society there have been people whose behavior differed from the rest of society. There are many different theories and perspectives on why people do things like abuse drugs, and although we my never have all the answers, sociology still help us to understand the problem better. In order to understand the theories of deviance, and apply them to drug use in our society one must first understand what deviance is. Alex Thio defines deviance as an