Effect of Parasite Diversity and Age on Antibody Responses

Effect of Parasite Diversity and Age on Antibody Responses This study was aimed at investigating the effect of parasite diversity and age on the levels of antibody responses to P. falciparum in individuals living in an area of seasonal malaria transmission. Two blood stage antigens (MSP1(19), AMA1) and two liver stage antigens (CSP and celTOS), making a total of four antigens were selected to be used for the study. These antigens were tested in archived plasma samples with ages ranging from 1year to 70 years. The samples were collected close to the end of the rainy season in the months of November and December (wet season), and April the following year at the end of the dry season (dry season). Of the samples collected in the wet season, 34.1% had parasites whiles those collected in the dry season was 15.5% (table 1). Appawu (2004) reported the seasonality of malaria transmission in a neighbouring district (Kasena Nankana District), being high in the wet season and low in the dry season. The high transmission in the wet season could be due to favourable breeding grounds for mosquitoes as a result of several collections of water when it rains and in turn increase the number of vectors and hence the high number of parasites individuals are exposed to (Ahmed, 1989). This data is in agreement with an earlier finding in northern Ghana by Apawu and his group where they found high parasite carriage, and high multiplicity of infection (MOI) in the wet season compared to low carriage and MOI in the dry season. Parasite carriage here means the proportion of participants with P. falciparum at enrolment. There was however no statistically significant difference in the parasite densitie s when compared between the seasons (p=0529) table 1. There was no difference in the overall ages between the wet and the dry season. (p=0.937). This was expected as most of the samples collected were from the same individuals in the two seasons. To explore age related pattern of P. falciparum infection, participants were categorized into three (3) age groups: under 5 years, between 5 and 15 years, and over 15 years. The data shows the 5-15 year olds having higher infected proportion in the two seasons (table 2). Parasitaemia was also determined using a more sensitive method, the polymerase chain reaction (PCR). The PCR data confirmed the microscopy data because the 6-15 year group also had higher proportion of individuals carrying parasites at enrolment. This could be due to the fact that they are the more exposed group with incompletely developed immune systems. In contrast, under-fives who are much younger are likely to receive better care from parents thus preventing them from being infected with the parasites. Bed net usage could be one way of protecting the children. Also because of their younger ages they may not be allowed roam around freely. Adults on the other hand despite having possible similar exposure as 5-15 ye ar olds, seem to have less parasites because of their developed anti-malarial immunity. This partial immunity is gained with age and repeated exposure thus making the younger individuals more susceptible to infection (Pratt-Riccio et al., 2005; Dodoo et al., 2008). Thus the over 15 year group who are older, had the least proportion of infection (table 2). The study also sought to determine the relationship between IgG levels and age. Figures fig 7 and 8 shows the correlation plots between age and IgG levels in the wet and dry season respectively. There was a significant positive correlation between and IgG levels raised against AMA1-FVO, MSP1, CSP and CelTOS in the wet season. And for the dry season, the significant correlation was between age and IgG levels to AMA1-FVO, MSP1, CSP, and Celtos. The correlation coefficient (r2) and the p values are indicated on each plot. There was however no correlation between age and AMA1-3D7 (r2 0.0142, p 0.0699) for the wet season, and AMA1-FVO (r2=0.0114, p= 0.0594) for the dry season. The significant correlations were however very weak. This indicates that though IgG levels increased with age, the association between the antibody levels and age was not so strong and that the influence of age on the amount of antibodies produce against most of the antigens in the population studied was not that mu ch. However the age dependent increase in IgG response to the antigens tested may be due to the mature immune system in adults, and could also be due to cumulative exposure to infection over time (Nebie 2008). It is however not known what might be the reason for the lack of correlation with age to AMA1-3D7, and AMA1-FVO, in the wet and dry season respectively. IgG responses to the two AMA1 alleles (3D7, and FVO) was plotted against each other to determine which is more predominant in the study population. There was a strong correlation between the antibody levels of AMA1 alleles of 3D7 and FVO (r2=0.8382, p) implying that both strains are circulating in the study site during the wet season. A similar trend was observed in the dry season but with a lower correlation coefficient compared to the wet season (r2= 0.5302, p). Antibody titres against recombinant antigens have often been linked to protection from clinical disease (Polley 2004, Nebie 2008, Dodoo 2008, Dodoo 1999, Cavanagh 2004). Where high anti-malaria antibodies is interpreted to mean protection from clinical disease. The important role of antibodies was demonstrated by the passive transfer of purified IgG from immune donors to individuals with P. falciparum infection, which reduced parasitaemia (Cohen 1961, sabchareon 1991). Apical membrane antigen-1 AMA1 and MSP119 have been associated with reduced risk of clinical malaria (Branch 1998, Osier et al 2008). Anti-CSP antibodies have also been found to be partially protective where in Kenya high anti-CSP, anti-LSA, and anti-TRAP ( pre-erythrocytic ) antibodies were demonstrated to be associated with relative protection from reinfection (John CC 2005, 2008). The most advance malaria vaccine, RTS’S which is a subunit of CSP, has been found to protect to about 35-55% in children 5-17 mont hs for about 8 months (Alonso 2004,) . Also anti-CelTOS antibodies have been shown to inhibit invasion of herpatocytes by sporozoites in mice (Bergmann-Leitner 2010). In this study, antibody responses to the antigens, AMA1-3D7, AMA1-FVO, MSP119, CSP, and CelTOS were determined using indirect ELISA. The optical densities (OD) of the antigens were converted to arbitrary units (AU) where the highest OD for each antigen was awarded an arbitrary unit of 4, to allow for comparison between antigens the antigens tested. Antibodies to AMA1 in individuals living in malaria endemic regions have been reported to be high, (Thomas,1994, chelimo, 2005), and this study thus reports high antibodies to AMA1-3D7, and AMA1-FVO compared to MSP1(19), CSP, with anti-CelTOS antibodies being the least. (Fig: 3) in both wet and dry seasons. The data also shows total IgG responses in the wet season was higher than the in the dry season for all the antigens (p) except MSP119 where no statistical differences wa s found between the two seasons (p=0.85) (Figure 3). The seasonal changes in antibody response could be as a result of higher number of vector (mosquitoes) in the community in the wet season which could in turn increase the exposure of the population to parasites and also introduce new parasite clones/strains in the population and hence the high anti-malaria antibodies found in the wet season. In contrast, the dry season cause a reduction in the number of breeding sites for the vectors reducing their population resulting in minimal exposure and hence the low antibody levels. In malaria endemic regions, the number of different clones of Plasmodium falciparum parasites infecting a person could be a transmission indicator, an indicator of the hosts immune status, and a useful parameter in evaluating malaria control interventions (Babiker 1999, Arnot 1998, mayengue 2009). It has also been reported that parasite diversity in high malaria transmission areas are high and that individuals could carry multiple genotypes (clones) but the opposite pertains in low endemic areas with most infections being monoclonal (Peyerl-Hoffmann 2001, Bakiker 1997, Haddad 1999). Genotyping was done using block 3 region of the MSP 2 gene (Smythe et al. 1990) because of its high polymorphic nature (Felger et al.,1994 1999; Robert et al., 1996). Also MSP2 was selected to be used for this study because of the high allelic diversity observed in Ghana and other countries bordering Ghana with as many as 154 alleles in Ghana and about 50 genotypes in CÃ ´te d’Ivoire. ( Silue 2006 , falk 2006). The results from the two seasons using the 3D7 allelic family primers showed high mean multiplicity of infection in the wet season compared to the dry season (1.76, and 1.46, p=0.001) table 3. In both seasons, the number of infections per person ranged from 0 to 4. A similar degree of multiple infections has been reported in other African settings (Ntoumi et al., 1995,Beck 1997, Engelbrecht 1999). The samples used for this study was collected in asymptomatic individuals and the high multiplicity of infection found in the wet season could probably be due to high rate of exposure as a result of favourable breeding conditions compared to the dry season. This study did not find any significant correlation between MOI and age in both seasons (p=0.5768 for wet season, and p=0.4158 for the dry season). The samples were then grouped into two based on whether positive or negative using PCR to detect Plasmodium parasites. No differences were detected in the IgG levels between th e antigens tested in both seasons when compared based on the PCR data. This result is similar to that found when microscopy was used except that anti-CelTOS IgG in the parasitaemic group was higher than the non-parasitaemic group when microscopy was used. The disparity in the CelTOS report could be due to the lower sample size analysed using PCR compared to the microscopy. Apical membrane antigen AMA1 has been found to be a promising blood stage vaccine candidate antigen but this potential has been dampen due to extensive polymorphism (Remaque 2008).

Exploring Research Methodologies: Positivism and Interpretivism Essay

Exploring Research Methodologies: Positivism and Interpretivism Before a researcher can initiate a research project, they face the confusion and the range of theoretical perspectives, methodologies, methods, and the philosophical basis that encompasses them all. This seemingly meticulous structure for the research process is in fact aimed toward providing the researcher with a ‘scaffolding’, or a direction which they can go on to develop themselves to coincide with their particular research purposes. (Crotty, 1998) Once a researcher has developed a research question they are seeking to answer, they must consider what methodologies and methods they will employ in the research; what theoretical perspective lies behind the methodology; and what epistemology informs this theoretical perspective. (Crotty, 1998) Before continuing it is important to explain these key terms: Epistemology is ‘the branch of philosophy concerned with the theory of knowledge, which seeks to inform us how we can know the world.’ (Jary and Jary: Dictionary of Sociology, 1991) In the context of social research, epistemology is the form of proof one requires to justify a claim to knowledge about the social world. This will have a salient impact on the kind of data one can collect in order to validate their arguments concerning the social world (methodology), as well as the methods one considers in collecting valid data (methods). A researcher’s choice of methods will be conditioned by theoretical perspectives, the way one sees the social world. (Livesey) Researchers of social science use a wide variety of research methods to gain and enhance knowledge and theory. The different types of research methodologies, quantitative and qualitative, are associated with the epistemological and theoretical perspectives the researcher wishes to adopt. This choice the researcher makes determines the way in which research should be conducted. This paper will discuss, critically analyse and compare the epistemological and theoretical perspectives of two research methodologies used for social research: positivism and interpretivism. The various research methods used within the frameworks of each of these will then be discussed. Positivism There are two main types of epistemologies: positivist and anti-positivist. â€Å"Positivist research is an approach which combines a deductive approach w... ... 12.  Ã‚  Ã‚  Ã‚  Ã‚  Love, T. (1998). Value Role in Computer-assisted Designing. Western Australia: Dept of Mechanical and Materials Engineering. 13.  Ã‚  Ã‚  Ã‚  Ã‚  Neuman, L.W. (2000). Social Research Methods: Qualitative and Quantitative Approaches. Sydney: Allyn and Bacon. 14.  Ã‚  Ã‚  Ã‚  Ã‚  Orlikowski, W. J. & Baroudi, J. J. (1991). Studying Information Technology in Organizations: Research Approaches and Assumptions. Information Systems Research, pg 1-28. 15.  Ã‚  Ã‚  Ã‚  Ã‚  Pawson, R. & Tilley, N. (1997). Realistic Evaluation. London: Sage. 16.  Ã‚  Ã‚  Ã‚  Ã‚  Sarantakos, S. (1998). Social Research. Melbourne: Macmillan. 17.  Ã‚  Ã‚  Ã‚  Ã‚  Sharma, B.A.V., Ravindra Prasad, D. & Satyanarayana. (1984). Research Methods in Social Sciences. New Delhi: Sterling Publishers Private Ltd. 18.  Ã‚  Ã‚  Ã‚  Ã‚  Silverman, D. (2000). Doing Qualitative Research. London: Sage. 19.  Ã‚  Ã‚  Ã‚  Ã‚  Vrasidas, C. (2001). Interpretivism and Symbolic Interactionism: â€Å"Making the Familiar Strange and Interesting Again† in Educational Technology Research. In Heinecke, W. & Willis, J. (Ed.), Research Methods in Educational Technology. Greenwich, CT: Information Age Publishing, Inc. 20.  Ã‚  Ã‚  Ã‚  Ã‚  Wainwright, S. P. (2000). For Bourdieu in Realist Social Science. London.

Limitations of New Media

New media technologies may have little impact on politics, even change politics for the worse. It has little effect on civic engagement. New media technologies increased political knowledge among citizens already interested in politics, for users who are not, public sphere online is meaningless. Social media activists are more democratic, more knowledgeable about current political events and also somewhat more understanding of anti-government sentiment. As the new media technologies provide a platform to talk without consequence and response, they have been widely sed by extreme groups to shape the citizenship and distort democracy.Such as 2011 England riots, the event was also called â€Å"BlackBerry riots† because people used mobile devices and social media such as twitter and facebook to organise. This Issue was launched majority by young people, who face the fierce competltlon and huge employment pressure. They are also the primary users of the social media network. In thi s Issue, two man , 20 year old Jordan Blackshaw and 22 year old Perry Sutcliffe- Keenan had been sentenced to 4 years In Jall for attempting to use Facebook to rganize and orchestrate† disorder.Blackshaw created a Fackbook event Smash Down Northwich Town, Sutcliffe-Keenan also set up a page encouraging rioting in Warrington. As Assistant Chief Constable Phil Thompson warned, â€Å"The sentences passed down today recognize how technology can be abused to incite criminal activity, and send a strong message to potential troublemakers about the extent to which ordionary people value safety and order in their lives and their communities. † As shown in the London riots, Twitter users send a message to millions. SoTendentious information and hate speech of the extremists can also spread quickly on the twitter, it would stimulate public dissatisfactions of government and make more people who dont know the truth fear and anger. So openness and freedom of the online platform prov ided by new media technologies reinforce the sense of citizenship and democracy but also have potential to disrupt social order and democracy. 2, Digital divide: Disadvantaged groups- (the poor, the elder, the undereducated, and thous In rural areas-continued to lag behind in their access to and use of the internet.People who lack required knowledge, skill and capital are not easily access to the Internet. Let alone use blogs or youtube. They continued to lag behind In access to the alternative public sphere. 3,For Journalists on social media such as Twitter: Issues of credlblllty. As social media has Impacted the speed of spread of Information and news. There are sometimes situations where the news can be misinterpreted and misleading. It Is only human nature to add and edit what they hear to make It sound better In their minds and this endency Is what makes the â€Å"unofficial news† unreliable.The User Generated Content usually lack of professionalism. It Is called cltlzen Journalism but when a story Is reported even in a post on Twitter or Facebook or Youtube, professionalism is key. story. But usually citizen Journalists record an event and present it to the public, very often without checking all the facts related to the event. 4,political inequality: The differenece between speaking and being heard. It is true that citizens face few formal barriers to posting their view on the twitter or youtube.This is openiness in the most trivial sense. But from the perspective of mass politics, we care most not about who posts but about get read. There are plenty of formal and informal barriers that hinder ordinary citizens' ability to reach an audience. For the enormity of the content available on social networking sites, people seem to cluster strongly around the top few information sources in a given category. Such as â€Å"trending topics† on the twitter, even through these topics recommened intent to help their users to know what is happening in t he world.Trending topics are ometimes the result of concerted efforts and manipulations by preteen and teenaged fans of certain celebrities or cultural phenomena. Public sphere provided by the new media technologies in some extent is not equal for the public to make voice. The elite domination still exists like in the mainstream media. 5, state interference, influence the watchdog function of social media, Although state interference in the political discussion on the social media is generally neglected in the Western world, it is still a major obstacle for truly open, free discussion to happen n less developed democracies.For example, the central government of China employs â€Å"professional writers† to insert the state voice in many corners of social media chat rooms in HongKong and help create a bottom-up participatory control. So falling to see actual political change to arise from their opinion expressions, normal citizens end up voicing the most extreme opinions. Sacri ficed in this process is the diversity of opinions and democracy. To conclude, Citizenship refers to the individual citizen self-awareness of his or her position in the nation.It concerns the right to know and speak for public in the democracy society. New media technologies reinforce the sense of citizenship and democratization because Rather than passively receive what the media want to inject to them, people in new media age are more active. The openness of the digital media would allow citizens to compete with Journalists for the creation and dissemination of political information. It broadens the â€Å"public sphere†, gives chances to citizens to engage in the political discussion, challenge domination and allows motivated itizens to be heard by a worldwide audience.But there are also limitations, the extensive use of new media technologies by extreme groups would incite criminal activities and distorts democracy. Disadvantaged groups continued to lag behind in their acc ess to the alternative public sphere. The new media technologies have served to level some existing political inequalities, but it has also created new ones. Government interference in the political discussion will break the Watchdog function of the new media.

Weak Electrolyte Definition and Examples

A weak electrolyte is an electrolyte that does not completely dissociate in  aqueous  solution. The solution will contain both ions and molecules of the electrolyte. Weak electrolytes only partially ionize in water (usually 1% to 10%), while strong electrolytes completely ionize (100%).   Weak Electrolyte Examples HC2H3O2 (acetic acid), H2CO3 (carbonic acid), NH3 (ammonia), and H3PO4 (phosphoric acid) are all examples of weak electrolytes. Weak acids and weak bases are weak electrolytes. In contrast, strong acids, strong bases, and salts are strong electrolytes. Note a salt may have low solubility in water, yet still be a strong electrolyte because the amount that does dissolve completely ionizes in water. Acetic Acid as a Weak Electrolyte Whether or not a substance dissolves in water is not the determining factor in its strength as an electrolyte. In other words, dissociation and dissolution are not the same things. For example, acetic acid (the acid found in vinegar) is extremely soluble in water. However, most of the acetic acid remains intact as its original molecule rather than its ionized form, ethanoate (CH3COO-). An equilibrium reaction plays a big role in this. Acetic acid dissolves in water an ionizes into ethanoate and the hydronium ion, but the equilibrium position is to the left (reactants are favored). In other words, when ethanoate and hydronium form, they readily return to acetic acid and water: CH3COOH H2O ⇆ CH3COO- H3O The small amount of product (ethanoate) makes acetic acid a weak electrolyte rather than a strong electrolyte.