Category: Sciences 2502

Introduction

All Chemical reactions, reproduction processes, cellular functioning, and general body development require energy for proper functioning. Deficiency in energy supply to body parts leads to death in all living organisms. Photosynthetic organisms utilize the sun as their main source of energy, through the conversion of solar energy to chemical energy. Other organisms (not photosynthetic) depend on the energy that is stored in photosynthetic organisms.

Metabolism comprises all chemical reactions that sustain living cells. It is divided into two: anabolism and catabolism (Ophardt, 2003, Para. 1, 2). Organisms use specific adaptive characteristics that are either behavioral or biological to adapt to their habitats. This paper will discuss different organisms cells and their adaptive characteristics about metabolism and respiration.

Cells

Cells are the building blocks of life. They help the organism absorb nutrients and convert the nutrients into energy. In addition, cells perform other specialized functions in the body that sustain organisms. There are two types of cells: prokaryotic and eukaryotic. Prokaryotic cells are found in single-celled organisms, whereas eukaryotic cells are found both in unicellular and multicellular organisms. (Cell, 2009, Para 1-7).

Bacterias Prokaryotic cells

Bacteria are single-celled microscopic organisms. These cells have neither a nucleus nor other organelles for example the mitochondria and chloroplasts. These organisms reproduce mostly asexually. They exhibit different metabolic traits hence defining their taxonomy.

Their metabolism is divided into nutritional groups depending on three factors: energy sources, electron donors, and the origin of carbon. The nutritional types are phototrophs, organography, and lithographs. Autotrophic microorganisms, obtain their carbon through fixation, Lithographs make use of inorganic electron donors whereas; organography uses primarily organic. Most respiratory bacteria utilize chemical compounds to make energy. The organisms achieve this by removing electrons from broken substrates and changing them into electron acceptors (Mcguigan, 2009, Para 1-6).

Bacteria have several structures that help them to adapt to their habitats. These structures are the plasma membrane, cell wall, capsule, ribosomes, nucleoid, pilus, and flagellum.

The cell wall

The Bacteria cell wall is made up of peptidoglycan. This gives the cell its shape and covers the cytoplasmic membrane. Peptidoglycan is made up of glucose derivatives: N-acetyl muramic acid and N-acetylglucosamine. In gram-positive bacteria, the cell wall is mostly made up of peptidoglycan. On the other hand, gram-negative bacteria have a complex cell wall (chemically), where peptidoglycan is minimal.

Fine-tuning of the biophysical conditions by the bacteria cell wall helps it to adapt to changing environments. For example, in cases where the lipid bilayer is high, some bacteria will produce lysine that will neutralize the effect. Many bacteria resist cationic antimicrobial peptides by minimizing the negative charge on their cell wall. The wall is very strong, hence adapted to respond to changes in osmotic pressure. In addition to protection, the cell wall also helps bacteria to resist disease attacks (Davidson, 2009, Para. 5, 6).

The flagellum

Motility assists bacteria to obtain nutrients. In addition, it helps bacteria to protect themselves from predators and dangerous chemicals. The flagella are hair-like structures found on either the bodys sides or the whole body. They are long and rotate to enable bacteria to move faster in all media. They have nucleoid and cyclic catabolite proteins that are activated to provide energy during motility. To respond to poor carbon sources, they activate their chemotaxis genes, hence enabling the move to favorable environments (Burgess & Mingzhu, 2007, p. 4451-4456)

Animal- eukaryotic cells

Animals are multicellular organisms. Their cells do not have a cell wall. All animals are motile, although some do not have muscles for movement. Animals bodies have skeletons that help in mobility, protection, and support. Their cells have many organelles that function differently. Some of these organelles are the lysosomes, mitochondria, centrioles, and ribosomes. Animals have diploid cells hence, the occurrence of chromosomes in homologous pairs.

Mitochondria

The mitochondria are elongated structures found in the cytoplasm. Their main function is to provide energy by converting nutrients. In addition to providing energy, it helps the body in cell differentiation. It has sections that perform different functions. Its parts include the inner and outer membrane, matrix, and cristae. They also have proteins that vary with species and tissues. It produces adenosine triphosphate through the conversion of nutrients. It further, converts pyruvate, sugars that are produced in the cytosol to energy. It achieves this through either aerobic or anaerobic respiration. They help also help to control the metabolic rate through muscles.

The mitochondrias outer membrane is smooth but the inner membrane is highly folded forming the cristae. The crista is folded to increase the surface area for respiration. The outer membrane prevents the entry of big particles into the matrix; it has a protein called porin. The inner membrane is structured to only allow proteins that have correct molecules (Davidson-mitochondria, 2009, Para. 1-4).

Ribosomes

On the other hand, ribosomes help the body to translate DNA sequences into proteins. They are made up of ribonucleic acids and proteins. In addition, they have two components for effective working. Each of these components has a specified number of RNA. Ribosomes are created in the cytoplasm through copying of their genes called operons. They either are located in the cytosol or attached to the endoplasmic reticulum. They organize amino acids into polypeptide sequences, by sticking themselves on RNA molecules; which coins the required order of amino acids. The body can change the number of ribosomes depending on metabolism requirements; hence their adaptive mechanism (Rice &Harnett, 2009, Para 1-4).

Conclusion

In conclusion, the cell plays a very important function in an organisms survival. These functions include molecule transport, reproduction, and energy production. The connections between these structures enhance an organisms performance levels hence ultimate survival.

Reference List

Burgess, R. R., & Mingzhu, L. (2007). Adaptation in bacterial flagella and motility systems: from regulon members to foraging-like behavior in E. coli. Nucleic acids research 35(13), 44414452.

Davidson, W. M. (2009). Bacteria Cell Structure. English simple dissector. Web.

Mcguigan, B. (2009). Types of bacteria. Wisegeek. Web.

Ophardt, E. C. (2003). Metabolism and energy. Virtual chembook: Elmhurst College. Web.

Rice, D., Harnett, A. ribosomes. 2009. Web.

Science clarified. (2009). The cell.Admeg. Web.

Introduction

There is a number of various information sources that are related to the nursing discipline and are available on the Internet and in certain journals. Thus, it is necessary to understand the basic principles of a critical assessment of research and know how to use them in interprofessional healthcare practice. Evidence-based practice is aimed at employing a three-pronged approach through blending clinical expertise, values and preferences of the patient, and the most appropriate research evidence. The purpose of this paper is to analyze two articles: one of them is primarily quantitative, and another is primary qualitative research.

Quantitative mobility assessment for fall risk prediction in dementia: A systematic review

The Purpose of the Study

The purpose of this systematic review was to provide critical research and analysis of the evidence that is able to link quantitative measures of balance and gait to the risk of falls in older adults who have dementia. Moreover, its aim was to adequately assess the risk of falls (Dolatabadia et al., 2018). It included the usage of clinically meaningful protocols and metrics that are appropriate for people with dementia.

Research Used to Support the Study

The literature research was conducted in July 2017, and a number of electronic databases, including Medline, Web of Science, Compendex, and PsychINFO were searched for studies. Moreover, keywords and terms related to the subject were used in order to capture the concepts of Gait/Balance, Falls, and Dementia (Dolatabadia et al., 2018). Only those English-language retrospective and prospective clinical studies that measured gait or balance included older adults with dementia and examined falls as an outcome were selected.

Data Analysis

All research results were checked and combined for duplicates, the articles abstracts and titles were reviewed, and irrelevant studies were excluded. After that, titles and abstracts of the articles were independently reviewed by the two authors, and a third party resolved all disagreements, and a flow diagram of the study selection was created (Dolatabadia et al., 2018). It is essential that all the papers authors contributed to the selected articles analysis.

Methodology

The chosen method for conducting the study was to analyze a number of other articles. They were not chosen randomly; instead, the members of the team selected only those articles that suited specific parameters. The implications for future research and the studys outcome are supported by the evidence that is presented in the article (Dolatabadia et al., 2018). As for the cultural considerations, the researchers gained the approval of the authors of analyzed articles and did not infringe anyones rights.

Strength and Limitation

The strength of this study was that data analysis was performed rather professionally. However, there also was a limitation related to the clinical generalizability and feasibility of the studies. The problem was that many of the researches either involved a rather short follow-up after only one assessment or were cross-sectional (Dolatabadia et al., 2018). The heterogeneity of the disease makes it almost impossible for a single cross-sectional assessment to identify people who are at risk of falling.

A qualitative exploration of chronic pain and opioid treatment among HIV patients with drug use disorders.

The Purpose of the Study

Approximately 39%55% of Americans who are HIV-positive report chronic pain, and finding a solution is crucial. Some evidence supposes that it may be associated with this diseases non-adherence to antiretroviral therapy and low retention in medical care (Isenberg et al., 2017). The purpose of this study was to explore the experiences of high-risk patients with pain management and providers regarding the clinical use of and access to prescription opioid analgesics.

Research Used to Support the Study

Recruitment of the participants was performed via flyers and from among people who took part in the ALIVE study and the AFFIRM study. In order to become a participant, people had to meet specific criteria (Isenberg et al., 2017). They had to have a history of using a forbidden drug, receive care at the Johns Hopkins HIV clinic, and be over the age of eighteen. In-depth interviews were conducted at a community-based research facility from August 2014 to May 2015.

Data Analysis

All the interviews were rather professionally transcribed; after that, the transcripts were thematically coded. During the coding process, the members of the research team discussed transcript coding, applied the constant comparison method, and organized meetings with a community advisory board and co-investigators (Isenberg et al., 2017). What is more, their aim was to achieve inter-coder consistency. Moreover, the researchers used an inductive and iterative process to unite emergent topics into themes.

Methodology

In-depth interviews were created and conducted in order to gather information related to the issue. To refine and identify several themes into a coding structure that successfully achieved theoretical saturation, the constant comparison method was used (Isenberg et al., 2017). After identifying all the major themes, the team members of the study chose notable quotes to support each of them. As for the protection of human subjects, before the research, all participants gave their written consent, and the Johns Hopkins School of Public Health Institutional Review Board approved all study protocols (Isenberg et al., 2017). Moreover, after the study, all participants were paid $25 for their effort and time.

It is possible to suggest that the limitation of the research was that those who did not speak English were excluded from the study. It provides a reason for doubting the trustworthiness of the whole study. As for its strength, it is excellent that the interviews were transcribed verbatim rather professionally. Since there is limited research on how HIV patients experiencing chronic pain engage with health care providers, this article is rather helpful for the implications for future research.

References

Dolatabadia, E., van Ooteghema, K., Taatia, B., & Iaboni, A. (2018). Quantitative mobility assessment for fall risk prediction in dementia: A systematic review. Dementia and Geriatric Cognitive Disorders, 45(5), 353-397.

Isenberg, S. R., Maragh-Bass, A. C., Ridgeway, K., Beach, M. C., & Knowlton, A. R. (2017). A qualitative exploration of chronic pain and opioid treatment among HIV patients with drug use disorders. Journal of opioid management, 13(1), 516.

The design research is constructed by the theory on making energy consumption lower and concrete steps on how to achieve it. In this respect two parts of the research stack up in terms of their cohesiveness with the main idea of the research. The internal validity of the research can be shaped in its direction to the common features applicable for designing rational approaches to solving the problem. However, the research maintained in the first part needs more observation from the part of previous (earlier) studies evaluating the issue of energy consumption. The question is that the theory can be clearly recognized in the sum of viewpoints on how to improve the situation. This is why the experience of the past could serve, as a great argument for the research.

The second part of the research that is concerned with measuring design matters has rather an attractive outlook. It is due to the essence of direct facts and assumptions on the topic of the research. Secondly, it is full of formulae describing relations between U-values and R-values. However, the choice of building (single story home) is not that fascinating. The most of the population in Europe and in the United States are living or working in multi-story buildings. It is considered with the demographic situation in countries of the world. For instance, the examples of Mayor House (in the form of glob) and Business Center (in the form of cucumber) in London can be realized as energy-saving buildings. What is more, the idea of materials with the law of thermal conductivity ought to be extended in detail.

Looking at the picture of possible threats to the internal validity of the research in its measurement the results vary. Thus, in terms of historic factors, there are no mismatches found in the research. The references and various statements do not contradict their sequence in the research. According to maturation factor, the research is readymade in features of its direct putting into practice. It means that the participants involved in the project can improve on their performance in issue on energy consumption easily.

The instrumentation in the research is stable in both parts. Thus, mainly rational theoretical and formula-based tools are described to have a clear idea about the research. The observation in two parts of the research gave no statistical regression. However, the threat in this respect is implied by the fact that there is no remark on the subjects involved in the realization of the research. A generally viable idea on the ecologically applicable means for architecture encounters a threat of experimental mortality. In this respect current situation outlines that not all participants in such an initiative would share the main idea of the research. On the other hand, the internal validity of the work is under the threat of the John Henry effect. It is so, because the innovative character of the research can probably be realized with the innovations, as such, but not with the role of innovators.

All in all, the internal validity of the research shows that the experimental treatment provides a mere extent of new features that could somehow make difference in terms of research significance. Thus, treatment and observation are well-exposed in the research. It is concerned with its general significance for humanity in the current stage of development.

Reference

Part 1. Design matters-conceptualize it.

Part 2. Design matters-measure it.

The concept of social ontology refers to exploring the nature and features of society. Comte, one of the most prominent French philosophers, discussed social ontology from the point of positivism. The ideas of this philosopher composed the fundamentals of modern sociology. Comtes law of three stages shows the evolution of society and sets the prospects for its future development, including such stages as theological, positive, and metaphysical ones.

Comte considered society from the point of positivism and realism, stating that people existed only as abstract in that period. It meant that the social reality denied an individual life, and thoughts and feelings were attributed to either biology or sociology. In other words, the mentioned philosopher excluded psychology from explaining the phenomena that characterized people. Instead, society was described as a continuous whole and a biological entity, which consists of different parts that are involved in various activities. For example, Comte stressed that families produce individuals, while the commonly accepted view was contrary to this statement (Ashley and Orenstein 82). Accordingly, families shape cities and cities form societies, where families serve as distinct, functional parts.

Another direction of social ontology was associated with the etymologization of human attributes. Namely, Comte distinguished between cognitive (conception, contemplation, expression), affective (egoism, sexuality, attachment, pride), and active functions (firmness, prudence, courage) (Ashley and Orenstein 91). According to the view of this philosopher, an individual should have been passing all the stages of development to arrive at positivism. Nevertheless, not all persons were considered to have equal intellectual abilities. The highest level was to be achieved only by a minority that would understand and change the world. As for minorities, Comte denied racial and ethnic differences regarding intellectual ability but believed in male intellectual superiority, which makes them the only persons who can study reality and scientific issues. However, it should be stressed that children and females were seen as important individuals who can impact men, thus promoting social harmony.

As a philosopher, Comte argued that sociology should be a practical discipline to discover new knowledge and implement it in the constant improvement of society. The work of this scholar was based on the French society that was considered to be in an urgent need to receive changes (Ashley and Orenstein 77). Among the key negative issues of that society, a lack of spiritual integration and stable political order was noted. The theory of social ontology suggested by Comte was expected to address the above challenges. In addition, ideological disagreements and governmental corruption were included in the list of social atrocities to be eradicated. This social imagery was based on the recreation of a unified spiritual order that would help to institutionalize a new era of political and social stability (Ashley and Orenstein 79). The achievement of this goal was expected to replace the canons of the Roman Catholic Church, but prevent chaos and contribute to the al harmony.

To conclude, social ontology by Comte studies the properties and nature of the social world, focusing on social interactions. Individuals, families, cities, and societies were perceived by this philosopher as the key entities shaping the social world and able to change it for the better. Comtes understanding of social harmony in France was based on addressing political disorder and poor spiritual integration through the transformation of social norms and achieving spiritual and political stability.

Reference

Ashley, David, and David Michael Orenstein. Sociological Theory: Classical Statements. Pearson College Division, 2005.

Introduction

Biometrics refers to the use of uniquely identifiable human characteristics to secure systems. Biometric information like height, hair color, weight, and eye color has been used for a long to assist in the physical identification of individuals. However, the constant change of biometrics and the ease with which they can be manipulated has led security personnel to use biometric data that remains the same with changing age and health. This biometrics is not as easy to fake as the earlier biometrics. The essay examines this form of biometrics.

Examples of biometrics

There are many biometric schemes used for beefing up computer security. The security accorded by each of them depends on its suitability for use in the system to be secured. Examples include fingerprint identification, face recognition, hand geometry biometrics, retina scan, iris scan, voice analysis, vein analysis, signature etcetera. Each of the above biometrics can be faked in one way or another and each of them is most appropriate in specific conditions. Although biometrics has some problems, it has played a very important role in the field of computer security and it is important to acknowledge its contribution.

Benefits of biometric security

Biometric technology is no longer fictitious. Although major advancements are still expected in this technology, biometrics has evolved to become one of the most important security innovations of all time. The need for use of biometric technology has been compounded by the fact that common security methods like the use of Passwords are characterized by a lot of problems.

Kemibaro, Harry. Biometrics security overview

For instance, some passwords are easy to hack, people may forget them, and people may keep passwords in notebooks. Some of the advantages of biometric technology include: biometric security through identification of people is very critical in the provisioned of access to information. Authentic users of information are securely and accurately identified by the biometrics before they are granted access to the information. This is usually achieved through the use of fingerprint identification, retinal scans, and iris scans that are capable of unique identification if done properly. Most biometric technology is automated and thus the scans are quick and standardized. The scans can also be carried out by minimally-trained personnel. Lastly, biometrics gives a means of identifications without the use of physical documents that can easily change hands, be lost, be damaged, or altered.

Vulnerabilities of biometric security

The fact that biometrics use parts of the body that have other functions have more than compensated for the weakness associated with biometrics. People use their hands and fingers in performing various activities. This way, people leave their fingerprints in virtually everything that they touch. With proper recording, these fingerprints can be transferred to fingerprint detection systems and authenticate unauthorized access to information. With an understanding of the common patterns of fingerprints, fake fingerprints can also be created. To evidence this, a Japanese expert has been able to create fake fingerprints that were approved as authentic by a biometric thumb scanner. It is also amazing that a thumb scanner using capacitive resistance can be fooled by just blowing over the reader after an authentic user has used it.

Dunn, Jones. Biometric Authentication Technology: From the Movies to Your Desktop

Schneider, Leakey. Biometric Authentication: What method works best?

This is explained by the fact that after authorized login, latent oil from the thumb is left on the capacitive surface with the fingerprint signature. Blowing the surface thus makes the reader sense the fingerprint pattern left and thus the reader authenticates login/access. Each existent biometric has specific weaknesses that make it vulnerable to exploitation by malicious people. In Germany, a facial recognition scanner was fooled into making positive scans by a short video shown to its camera. In the same way, a voice recognition system can be easily fooled by a voice recording. Biometrics can also deny an authorized person from accessing the system they secure. This is especially evident after repeated attempts of unauthorized access (⁴). It can be literally argued that the biometric becomes accustomed to denial of access such that an authorized attempt at login/access is considered unauthorized. Therefore, as long as biometrics remains prone to manipulation they will never be able to solely secure systems.

Conclusion

Although biometrics have a considerably large number of shortcomings, they are very essential in the provision of security. The contribution of biometrics to the building of impenetrable security systems especially in the military is massive. It is therefore of great essence that we major on the strengths of biometrics and deal with its weaknesses. One of the mistakes that we make in building our security systems is the overreliance on biometrics.

• McFarlane, Ben. Biometric security is merely skin-deep
• Maltoni, Davide. Biometric Authentication Workshop

Although passwords have proved to be practically insecure, it is not wise to replace passwords with biometrics. Biometrics should thus be used as an enhancement for passwords. Consider an ATM (Automated Teller Machine) security system that requires a PIN as well as a fingerprint. Even if somebody gains access to your fingerprint, it will be very hard for them to get your PIN in order for them to get the complete access code. Therefore this kind of security is better than that of the PIN alone or a case in which the PIN is replaced with the fingerprint scan.

References

Dunn, Jones. Biometric Authentication Technology: From the Movies to Your Desktop. Web.

Kemibaro, Harry. Biometrics security overview. 2008. Web.

Maltoni, Davide. Biometric Authentication Workshop. 2004. Web.

McFarlane, Ben. Biometric Security Barely Skin-Deep. 2009. Web.

Schneider, Leakey. Biometric authentication: what method works best? 2009. Web.

According to the survival of the fittest concept, there is a mechanism of natural selection that leads to reproductive success. Darwins evolutionary theory refers to the species that can adjust to the environment to translate their attributes to the future generations. Based on the On the Origin of Species by Darwin, Spencer used the phrase survival of the fittest. As viewed by Spencer, Darwins theory could also be applied to humans to track their development and adaptability. Therefore, this author is widely known as a social Darwinist, who stated that those who fail deserve their failure, and those who are worth success, achieve it (Ritzer, 2011). It is possible to claim that the key difference between Spencer and Darwin is their social and biological approaches to evolution.

In terms of Spencers evolutionary theory, there are two main components, such as motion and matter. In the integration of these components, the matter transforms from abstract to definite forms, while motion experiences parallel changes. Compared to Darwin, who focused on biological changes of species, Spencer tried to understand the non-organic world, which can be referred to as cultural today. More to the point, Spencer stated that there is the principle that all the components have great attraction and the least resistance. Likewise Darwin, Spencer used biology to support his ideas, claiming that cerates struggling for the existence and winning would effectively adapt to the changing environment (Ritzer, 2011). For example, it was considered that simpler societies are likely to transform into larger ones, becoming compound societies. In comparison, both Darwin and Spencer stated that evolution occurs from homogeneous to heterogeneous and from simple to complex. While Darwin experimented with animals, Spencer imagined a more moral and developed society.

Reference

Ritzer, G. (2011). Classical sociological theory (6^th ed.). McGraw Hill.

Introduction

Generally, a quadratic equation has the following form: ax²+bx+c; with, c, b, and a being constant that are referred to as quadratic efficient, and x is a variable. In numerical stipulations, a quadratic equation is simply a polynomial-statement of a subsequent degree (Katz, & Barton, 2007). There are manifold methods of solving a quadratic equation, such as completing-the-square method; factoring; graphical method; employing quadratic formula; and Newtons method. Superlatively, the rudimentary task of a prime numeral is generally set up by the arithmetic theorem.

In mathematical terms, a prime-number is simply a natural numeral that has two distinct numeral divisors, i.e. the number itself and one (Stoppard, 1993). In this paper, someone will complete the weekly reading, i.e. up to Chapter 7 in the textbook entitled Mathematics in Our World that was written by Bluman G Allan; Thus, this paper aims at completing Project #1 and Project #2. In project 1, the paper will follow the example given by completing the six steps. In project 2, the paper will choose not less than five numbers, which can be odd, even numbers, or even zero, then substitute them in the formula to determine whether it yields a number that is composite or prime.

Project #1

To answer this project, we ought to follow a fascinating method to solve quadratic equations. This method is believed to have originated from India, and it is referred to as the completing-the-square method (Bluman, 2005). Thus, this method will be employed in solving these equations:

1. X²  2x-13=0;
2. 4x²-4x+3=0;
3. X²+12x-64=0; and
4. 2x²-3x-5=0

Project #1 Solution

We will follow the six steps as per the example given

1. 1. x²  2x = 13; Step 1, 4x²  8x = 52; then 4x²  8x + 4 = 56; from this,

We get (2x  2)² = 56; this implies that 2x-2 = 56 = 214, i.e. 2(x  1) = 214

Simplifying we get x  1 = 14; thus x = 1 + 14; Then 2x -2 = 56 = -214

From this 2(x  1) = -214, which can be expressed as x  1 = -14;

Therefore, x = 1  14

2. 2. X² 4x = -3; Step 1, 4×2-16x =-12; then 4(x² 4x) =-12; from this.

We get x²-4x =-3; this implies that x²-4x + 4 =1, i.e. (x  2)² = 1; simplifying we get

X-2 =1; thus x = 2 + 1 = 2 + 1 = 3; then x  2 = -1; from this x = 2  1, which can be expressed as x = 2  1 = 1

3. 3. x² + 12x = 64; Step 1, 4x²+48x=256; then 4x²+48x+144 = 400; from this,

We get (2x + 12)² = 400; this implies that 2x+12=400; simplifying we get

2x + 12 = 20, x=4; or 2x + 12 = -20, and x= -16

4. 4. 2x²-3x=5; Step 1, x²-1.5x=2.5; then 4×2  6x = 10; step 3, 4x₂  6x + 2.25 = 12.25;

Step 4, (2x  1.5)² = 12.25, step 5, 2x -1.5 = 12.25; and finally, step 6, 2x-1.5 = 3.5;

X= 2.5, or 2x  1.5 = -3.5; x= -1

Project #2

The searched formula that will be capable of yielding prime numbers is x²-x+41. This formula will be useful in this project, whereby at least 5 numerals for x will be selected and then substituted in this formula, so as to determine whether there is an occurrence of a prime number. Ideally, in this project, a numeral x that yields a composite numeral when substituted in the formula will also be found (Bluman, 2005). Thus;

Project #2 Solution

Let, P (x) =x²-x+ 41, lets plug-in the following values of x: x=1; x=2; x=5; x=10; x=12; x=20.

Then

P (1) =1² -1 +41= 41, this is a prime number; P (2) = 2²-2 + 41 = 43, this is a prime number;

P (5) =5²-5+4 = 61, this is a prime number; P (7) = 7²-7 41= 83, this is a prime number;

P (10) = 10²-10+41=131, this is a prime number; P (12) =12²-12+41=173, this is a prime number; and P (20) =20²-20+41=421, this is also a prime number. In fact, this list will continue to yield prime numbers until the value of x equals to 40. For instance, if x=41 then

P (41) =41²-41+41=1681, this is a composite numeral, but not a prime number.

Conclusion

The completing-the-square method can be employed in deriving the quadratic formula, to be capable of using the algebraic identity. Ideally, the majority of general notions that apply to the algebraic structure, in which multiplication, adding up and subtraction are defined, arise from prime numbers.

References

Bluman, A. G. (2005). Mathematics In Our World. College of Allegheny: McGraw-Hill Publishers.

Katz, V. J., & Barton, B. (2007). History of Algebra. Educational and Mathematical Studies, 65 (2), 180-199.

Stoppard, T. (1993). Arcadia. London: Faber & Faber.

Introduction

FOXP2 is a hormone that has been identified by scientists in living organisms which is responsible for the sounds that they produce. Science has made and is still making discoveries about the systems of living organisms with the effort to find out what causes them to behave in a certain manner. It is usually wondered why certain organisms contain almost similar features yet behave differently. Science is assisting in clearing such imaginations by finding out the make up of different organs that distinguish them from the others. A critical study has been done especially on humans and apes to find out the specific components in them that make them share much of the physical yet differ in character. Even though man is thought to have evolved from an ape, apes are said to have some underdeveloped features that limit them from behaving the way humans do. In this study, the hormone FOXP2 has been identified to be responsible for the various sounds that are produced in animals and humans. The sounds produced are however different because of the kind of amino acids that are used to build up the hormone in the organisms.

What is FOXP2?

FOXP2 stands for Forkhead box protein P2. It is a hormone that is involved in the regulation of human expression. If this hormone is mutated, it causes a serious language disorder in human beings. Giorgio asserts that, this hormone is also involved in the development of other tissues such as the lung and gut (5). He also goes forth to assert that, FOXP2 directly regulates a large number of downstream target genes (5). For example, it affects the CNTNAP2 gene, a member of the neurexin family. This gene is associated with common forms of language impairments. The hormone is found in both min human beings and chimpanzees but the difference in their makeup is displayed by two amino acids. These amino acids are responsible for the differences in the kind of speech that is displayed by chimpanzees and human beings (Giorgio 3). A study was carried out to find out how the difference in the amino acids impacts the two species. In this study, the neuronal models of the mice and the humans were used and the results suggested that the functions of FOXP2 were affected by the neuronal changes.

What is the function of FOXP2?

There are several functions that are played by this hormone in different organisms. Carmignotos described the function of FOXP2 as, the hormone which is necessary for enabling the proper growth of the lungs and the brain. According to him, the hormone is redirected to the tissues of the brain and the lung where it is involved in the mechanical process that will ensure that the brain adequately matures. This implies that a deficiency of this hormone will make an organism not behave as it is supposed to. Studies that have been carried out in mice reveal that mice with no functional copies of FOXP2 display abnormalities in brain regions and die 21 days after birth from inadequate lung development (4). This is basically because the mice may not be able to integrate the environmental factors and thus not be able to survive. The brain and the lungs are important in coordinating essential body activities that include the intake of oxygen, excretion and the likes. A mouse that is deficient in this hormone that has to assist in the coordination of such activities will therefore perish a few days after its birth. Another function of FOXP2 is the regulation of neuroplasticity in songbirds. The sound that is produced by the songbirds is due to the influence of the hormone on the brain that causes an urge within them to produce the sound. The young zebras have also been identified to benefit from FOXP2 which enables them to produce the sound that they usually produce. The level of FOXP2 in adult organism sdi9fferes from those that are still young, the sound produced may also differ according to the environment and the association thereof. For instances a male zebra will produce a significantly lower sound when singing to a female counterpart compared to other species. The same has also been observed in adult canaries.

There several evidences that FOXP2 is involved in human speech, it is however very reserved min human and takes a critical study for its location and existence to be established. Apart from the above mentioned organisms, the hormone has also been identified in birds and reptiles. However, it is not well conserved in non-human mammals. Even though the hormone is referred to by the same name in all living organisms, there has been a recorded difference min the number of amino acids in those organisms that make their sounds different. In relation to the amino acids that form the hormone in humans, the difference in chimpanzees are two amino acids, in mice, the difference is three amino acids and finally min zebras the difference is seven (Gathercole 24). Sherron indicates that, some researchers argue that this difference in amino acids between the human beings and the chimps is what has led to the evolution of language in human beings (462). Some further argue that this close difference in FOXP2 hormone is what has made the chimps closer to human beings than any other animal even in character.

Evidence that FOXP2 is involved in human speech

The investigation was carried out on the KE family revealed that the FOXP2 hormone may be the reason for some language disorders that have been experienced in the family for generations). It had been identified that the problem had been in the family for approximately three generations. An experiment was therefore done on the family members that were affected and those that did not display the abnormality to find out the exact thing that was responsible for it. From this investigation, the family revealed a disorder called autosomal dominant. Sherron indicated that, In this research, a scan was carried out on the genome of the affected and some of the unaffected family members (456). The first scan limited the affected space on chromosome which the group called SPCHI. To facilitate the success of the experiment, a chromosome clone that was bacteria in nature was used. As a control experiment, another person with a similar disorder was used who was unrelated to the family. After further research and investigations, this gene was called FOXP2.

Language is unique to humans. According to Carmignoto, human beings should be explored. This is important so as to understand how human brains uniquely combine to produce infinite meaning (9). Another component of language is vocal learning. This is the ability to modify innate vocalizations to unique new sounds. Vocal learners are animals with this ability. Human speech and birdsong are good examples of vocal learning. This two have provided molecular and physiological evidence. Rodents are not thought to learn their vocalizations. However, the recent discoveries that male mice produce song like sounds raise the question of whether such songs are learnt (Watkins 456).

According to Wolfgang, the complexity of language and the variety of speech and language disorders affects only one in every twenty children (869). There is a strong association between mutations and language deficits. Fisher gave the first link between FOXP2 and language (98). As Fishers asserts, Following investigations carried out on the KE family, the affected members of the family were found to have a heterozygous point mutation, which produced an amino acid substitution, R553H in the DNA- binding domain of the FOXP2 protein (99). However, Fishers discovery gives little understanding of how FOXP2 influences the brain. More scientists have tried to explain this condition, which they associate the FOXP2 protein with behavioral and neuro-imagining studies of a single mutation, the R553H, found in the KE family.

According to Wolfgang, despite of the ethical and practical limitations of human studies, analysis of FOXP2 function using human neuro-like cells grown in the laboratory can be highly informative (870). They can help in assessing disturbances in sub cellular localization. For instance, Fisher indicated that, the Fishers laboratory has each used chromatin immuno-precipitation to isolate fragments of DNA that are directly bound by FOXP2 protein in living neurons (100). This has allowed the successful isolation of downstream targets (Gathecole 154). According to Gathecole the FOXP2 gene is implicated in the development of human speech and language and a comparison of the human and chimpanzee FOXP2 protein highlights the differences in function in the two species (156).

FOXP2 and the Evolution of Language

The KE family was the basis of language impairment study. This family experienced severe difficulty in speaking. This disorder is associated with a mutation in a single autosomal dominant gene linked to a single genetic defect.

From the result soft the test, it was identified that the disorder is not grammar or speech specified. The symptoms that were displayed by the affected family members revealed that they were unable to construct sentences and speak them according to the rules of grammar, thy also had a difficult in coordinating the lips and the mouth for them to speak the words correctly. This condition also affected the IQ of the victims both in the verbal and non-verbal domain. From the findings, it was concluded that this condition was caused by a single gene trait. This gene was found to have a fork head binding, known as the Helix domain. The genes that contain this particular domain are called the FOX genes; the name was however modified to FOXP2 in accordance with nomenclature. Therefore, the problem in speech was a result of the nature of the gene. This shows that FOXP2 has the ability to affect the expression of a large number of genes. The problem of speech that is displayed in children as they grow up was identified to have begun in the embryo. This is the time when the embryo adapts some of the physical and mental characteristics of the parent which determine the character that they will display. There are a number of mutations that occur in the embryo of which will affects the development of the fetus. The mutation of the FOXP2 hormone has been identified to be the reason that affects the latter speech of the humans as they grow.

A study from Enard shows that FOXP2 IS highly conserved. In all cases investigated, the amino acid mutated in the KE family was identical. According to Enard, this gene is 715 amino acids long and it is identical with no differences in chimpanzee, gorilla and the rhesus monkey (868). Comparing the occurrence of the hormone min mouse in comparison to other apes, it was found that the amino acids in monkeys differed by one. Comparing the same with gorillas and chimpanzees, they were deficient in two amino acids (Enard 870). According to Enard, estimates of the mutations in the FOXP2 in the human lineage occurs over 100,000 years ago and it is suspected that these mutations are responsible for the development of human speech and brain (872).

To sum it up, many reports of FOXP2 claim that it is a gene of language. The development of language is not entirely based on a single mutation in FOXP2. There are many other factors that affect speech, this includes the larynx which affects human beings and makes them to choke food. As Giorgio asserts, the nasal cavity is able to close and hinder the vowels from being nasalized (15).

What would happen if the human gene was expressed in chimps?

According to Fisher, the human genome carries many genes that have no known function in humans but are functional in animals, for example, human being carry the gene for the mouse tail but the cells in the human being miss the switch to turn it on (78). This means that adding more mouse tail genes to the human body would not do anything new. Genetic materials are usually carried out across several species which may generally affect their genetic make up. It will make them to display characters that may have been thought to have gone with the previous generation. Analyses show that these viruses have been frequent visitors throughout generations (Motoo 718).

Many scientists have tried to develop chimeras in the laboratory but these chimeras do not survive to term (Giorgio 8). The genome that makes up the human character and that which is responsible for the same in chimpanzees has been studied and identified in full. It is therefore easy for scientists to draw a distinction on the characters that are displayed by humans and those displayed by chimpanzees.. Moving from paper to life would require embryonic technologies. Brain-expressed genes are known to evolve slowly in mammals. This means that the rate of evolution among brain expressed genes is low. In addition, evolution is less pronounced in brain specific genes making the human brain differ from that of his close relatives. According to (Kimura 716), coding for the brain is complex and highly constrained. He argues that too much change would impair brain activity. From his studies, he found out that interfering with the chimpanzee genome was likely to produce additional characteristics similar to those of the human being. Morally, the development of chimeras has being opposed by society. Religiously, trying to give chimpanzee human characteristics is interfering with creation which is meant to be sacred.

There have been efforts by scientist to try and mix up the genome of the chimpanzee and that of the human being to see if the characters can merge. A chimpanzee has been the target of these studies considering the many characters that it shares with the humans. Thy have been hence trying to put the speech hormones in chimpanzees to see if they would make them talk. This has however been in vain considering that the mechanical make up of a chimpanzee can not be compared to that of a human being. The exchange of such materials has been in fact identified to interfere with the make up of the two organisms. The FOXP2 hormone operates mainly in the brain and the lungs, this are crucial organs that can affect the functioning of the body if correct measures are not followed. Scientists have not given up on the study and they do believe that one day they will manage to integrate these hormones to achieve the desired results. FOXP2 hormone is a simple hormone that is composed of different features; the hormone may not remain to be the same because it is transferred from one organism to another. It has continued to display different natures in varying living organisms which is making nit complicated for the scientists to modify it. It is also not easy to obtain especially in humans considering the areas in which they are synthesized and produced.

In conclusion, the FOXP2 protein is responsible for human speech and cognitive development. If this gene was expressed in chimpanzees, it is not a guarantee that the chimps would talk and act like the human beings. This is demonstrated by the fact that human beings carry the mouse tail gene but do not express it physically. Similarly, increasing FOXP2 in chimps does not mean they would talk. Consequently, tampering with brain genes would only result in damage even to a point of ruining the cognitive capacity of chimps. It is not FOXP2 as a single gene that affects speech, but its the nature of combination with other cells, which is only unique in the human brain and not in the chimps brain. Efforts of producing human speech in a chimpanzee would just be futile (Giorgio 15). Mixing individuals violates their genetic uniqueness thus speech should be left as a unique quality of human beings only. This discovery could be in opposition to the theory of revolution where by man has been thought to originate from apes. Science itself has come up with findings that may reveal that the human genes and those of the apes may not be integrated. The few experiments that have been done have produced negative results that have diverse effects on the victims. In fact apes are rarely used to experiment the appropriate medicine that can be used in humans. Organisms that are mostly used for the same are mice which have revealed more promising results. The journey is however never final for the scientists who are forever behind their microscopes to feed the world with new findings.

Works Cited

Fisher, Gary. Accelerated evolution of nervous system genes in the origin of Homosapiens. New York: Atheneum publishers, 1998.

Gathercole, Susan. Phonological memory deficits in language Columbus. USA: Battelle Institute, 1990.

Giorgio, Carmignoto. What makes man different from other primates? Journal of Physiology, 559 (2006): 3-15.

Motoo, Kimura. On the probability of fixation of mutant genes in a population. Genetics 47 (1999): 713719.

Sherron, Watkins. Behavioral analysis of an inherited speech and language disorder. Journal of psychology, 125 (2002): 452464.

Wolfgang, Enard. Molecular evolution of FOXP2, a gene involved in speech and language. Genetics, 418 (2002): 869  872.

Introduction

Earth is the only known to scientists planet that has life. However, researchers have been trying to estimate the number of planets in other solar systems that have the potential of containing life. In the article Dynamical Packing in the Habitable Zone: The Case of Beta CVn, Kane et al. focus on exploring other inhabitable planets. This paper will summarize the article by Kane et al. and present a reflection on the matter.

Summary

The study in question was published in The Astronomical Journal and Science Direct. The topic of the research article relates to many scientific fields and issues, including physics and biology. The study was conducted by Kane et al., and the researchers focused on examining Earth-like planets. Past research on this topic focused on the exploration of the so-called habitable zone, which is an area near a star where orbiting planets can have a liquid (Surprising number of exoplanets could host life). Trappist-1 is a solar system located not far from the Solar System, and previously three planets within this system that can have water were identified by scientists. Therefore, the objective of the examined research was to determine whether Trappist-1 can have other inhabitable planets.

The researchers used computer modeling and the input of data about Trappist-1 to determine the gravity and other forces. As a result, Kane et al. found that within this solar system, some stars could support up to seven inhabitable planets (Surprising number of exoplanets could host life). Moreover, a star similar to the Sun supports six planets with liquid water. The researchers note that if a system has more than seven planets in the inhabitable zone, they begin to destabilize the orbits of one another.

Reflection

In my opinion, studies similar to the one by Kane et al. are critical because they help advance astrophysics and other scientific fields. Moreover, biologists and chemists can also benefit from this research since it contains some explanations for the atmospheric chemistry of these planets. This study relates to the content in this course because it shows the connection between different scientific fields and the potential of applying the acquired knowledge. Hence, although the focus of this research is on trying to find life outside the Earth, it also contributes to the development of multiple scientific fields.

By using models, similar to the ones developed by these researchers, others, for example, NASA can use their resources, such as telescopes to study the potentially inhabitable planets more precisely. Otherwise, the number of potential planets that should be considered in the first place would be too large, and the scientists would dedicate most of the time to trying to find these habitable zones (Surprising number of exoplanets could host life). Moreover, I think that similar studies are a valuable contributor to understanding how the conditions that allowed life to develop on Earth emerged. This process is complicated and time-consuming, and this study can help understand the specific requirements necessary to support the properties that make this planet inhabitable.

Conclusion

Overall, this article provides an outline of the research on the potential of other planets being inhabitable. Kane et al. successfully created a computer model that simulates the environment of the Trappist-1 solar system. They determined that the maximum number of inhabitable planets in it is seven. In the reflection part, the critical role of similar studies and their contribution to multiple scientific disciplines is discussed.

Work Cited

Surprising Number of Exoplanets Could Host Life: New Insights to Inform Future NASA Missions. ScienceDaily, 2020, Web.

Bacteria

The paper aimed to study the mechanism by which gram-negative bacteria resist killing by antimicrobial peptides which are found in a diverse range of organisms and help restrict the growth of invading bacteria. Earlier studies have shown that gram-negative bacteria acquire resistance to antimicrobial peptides through modification in the lipid A portion of the cell surface. Lipid A modification is regulated by a two-component system called PhoPQ (Derzelle et al, 2004; Ernst et al, 1990; Guo et al, 1997; Moss et al, 200; Rebel et al, 2004). It is composed of a membrane-bound sensor kinase PhoQ and the cytosolic response regulator PhoP. The present study carried out several experiments to determine how bacterial sensor kinase recognizes antimicrobial peptides. Activation of the PhoPQ regulated gene was studied in varying Mg2+ concentrations. The experiment showed that while PhoP activity occurred at lower concentrations, it was impaired at higher concentrations suggesting that the antimicrobial peptide competes with Mg2+ which binds either with the bacterial cell surface or to PhoQ directly. Further experiment showed that a mutant strain in which phoQ was deleted failed to activate a PhoP-dependent gene suggesting that PhoQ is required for response to an antimicrobial peptide. Based on the experiments, the authors concluded that PhoQ is an antimicrobial peptide sensor and its acidic surface binds to divalent cations to repress kinase activity and to antimicrobial peptides to activate kinase activity. Based on the data obtained from the experiment, the paper proposes a mechanism for PhoQ activation. They suggest that the negatively charged surface of PhoQ is perfectly suited to sense the presence of antimicrobial peptide and binds with it. This functions as a lever to lift the acidic surface off the membrane which leads to signal transduction.

Strengths of the Paper

The paper fills an important gap in the understanding of how gram negative bacteria are able to resist the inherent immunity of most organisms. While previous studies have shown that the PhoPQ system responds to sub-lethal concentration of antimicrobial peptide, the exact mechanism was unknown. The paper builds on past researches which have shown antimicrobial peptides interact electrostatically with negatively charged outer membrane of lipid A (Piers and Hancock, 1994; Sawyer et al, 1988). The results of the experiments are also consistent with earlier works which have also proposed that Salmonella resistance to ±-helical macrophage peptide is an important function of PhoPQ virulence promotion (Rosenberger et al, 2004).

Weaknesses and Suggestions for Improvement

The main problem with the paper is with way the data has been presented. The data obtained from the experiments has been shown graphically. A tabular representation of this data would have made it easier for the readers to understand and read it. Also the graphs are not properly labeled, making it very difficult to read them. For example figure 1 shows how antimicrobial peptides activate PhoPQ-dependent gene expression. But the graph does not have any legends making it very difficult to interpret it. Similarly, the results of the experiments are shown through the graphs in figure 5. These graph do not seem to be drawn to scale and give only a general idea of the results and not the accurate measurement. The explanation of figure 5b says that the fluorescence spectra wee recorded at the wavelength of 340nm, but the graph starts only at 400 nm. This discrepancy in the figure is not explained in the text either, suggesting that there is some mistake somewhere. Figure 5D is totally incomprehensible and superimposing the spectra of PhoQ in presence and absence of polymyxin nonapeptide does not serve any purpose. If the two spectra were presented in two separate graphs, it could have been easier to read them. Of course the best option would have been to tabulate the results to avoid confusion. One limitation of this paper is that it depends heavily on other papers and come to its conclusions based on indirect experiments rather than direct empirical studies.

Further Studies

Although there is a huge body of literature on the functioning of gram negative bacteria, the exact mechanism by which they are able to resist antimicrobial peptides is still not well understood. The present study attempts to find an answer based on experimental data. Although the results are consistent with past studies, the suggested mechanism is probably correct, future studies could try to directly observe the mechanism rather than come to conclusions based on indirect experiments. Also the paper does not study the mechanism by which PhoP promotes antimicrobial peptide resistance. Future studies could shed some more light on the role of PhoP in overcoming the antimicrobial peptides.

Trypanosomes

Akpan N., Caradonna, K., Chuenkova, M.V. and PereiraPerrin, M. (2008). Chagas disease parasite-derived neurotrophic factor activates cholinergic gene expression in neuronal PC12 cells. Brain Research. 1217. 195-202.

Summary of the Paper

The aim of the experiment was to study the affect of parasite-derived neurotropic factor (PDNF) produced by the parasite Trypanosoma cruzi, the parasite responsible for Chagas disease, on the expression of cholinergic gene in neuronal PC12 cells. In Chagas disease, PDNF binds with TrkA resulting in a multiple neurotrophic responses in neuronal cells. Given the importance of NGF/TrkA in triggering Chagas disease, the present study investigates if PDNF regulates the expression of choline acetyletransferase (ChAT) and vesicular ACh transporter (VAChT), proteins that define cholinergic phenotype in neurons. For the experiment, PC12 cells were treated with various concentrations of PDNF and analyzed for ChAt and VAChT. The results showed increased mRNA after 48 hours in both the proteins. Further experiments were conducted to investigate if T.cruzi invasion alters cholinergic gene expression by infecting PC12 cells with the parasite while all external parasites were removed. And later, the experiment was repeated with T.cruzi on the external surface while intracellular infection was removed. The experiment suggested that cholinergic gene expression is the result surface-mediated interactions between T.cruzi and host cell rather than intracellular infection. According to the authors PDNF stimulation of cholinergic gene expression could be responsible for recovery of parasympathetic function in Chagas disease. Based on these experiments, the authors conclude that PDNF could have therapeutic potential for Chagas disease.

Strengths of the Paper

The study added to the vast literature on the role of PDNF in activating cholinergic gene expression showing that Nerve Growth Factor (NGF) plays an important role in the maintenance of cholinergic phenotype (Lin et al, 2005; Tuszynski et al, 1990; Yeh et al, 1991; Auld et al, 2001; Ekstrom and Reinhold, 2004; Heisenberg et al, 1994). NGFs biological activities is to a large part dependent on signaling through TrkA, a member of tyrosine receptor kinase superfamily (Counts and Mufson, 2005; Miller and Kaplan, 2001). The study also shows that the relative presence of T. cruzi infection with the cell determines whether this infection is beneficial or harmful for the organism. If the infection is present on the surface of the cell, it increases the expression of cholinergic gene while if the infection is intracellular, it decreases its expression. This finding could have important ramifications for future researches on cure for Chagas disease.

Weaknesses and Suggestions for Improvement

The authors suggest that PDNF stimulation of cholinergic gene could aid recovery in Chagas patients. However, experiments do not support this conclusion and authors explanation of how they arrived at this conclusion seems incomplete. The entire discussion section of the paper makes assumptions about the significance of the results of the experiment. There is almost no discussion of the main finding of the experiment which is that the presence of T.cruzi on the external cell wall increased cholinergic gene expression while intracellular infection actually decreased the gene expression. A detailed in-depth discussion of this finding and its ramifications could have been done in the discussion section. Also, the paper does not give any suggestions for future research.

Another problem with the paper is that the results are difficult to find and are interpolated with the method. If the results had been tabulated or placed separately from the methods, it would have been easy to understand their importance. In general, the layout of the paper is very confusing and it becomes very difficult to locate the various aspects of the experiment. Figure 4b shows the results of quantitative PCR, but the graph is not very clear. Also no mention is made of this graph anywhere in the text and seems to have been included as an afterthought.

Further Studies

Further studies could build on the findings of this paper and attempt to find cure for Chagas disease. Also, if the relative position of T.cruzzi cell can have completely opposite affect on gene expression, other parasites which influence gene expression could also show similar characteristics. This could be further studied and may help in finding cures for other diseases where a parasite affects gene expression.

Fungi

Legrand F., Lecuit, M., Dupont, B., Bellaton, E., Huerre, M., Rohrlich, P. and Lortholary, O. (2008) Adjuvant corticosteroid therapy for chronic disseminated candidiasis. Clinical Infectious Diseases. 46(5). 696-702.

Summary of the Paper

The aim of the experiment was to study the efficacy and tolerance of corticosteroid therapy (CST) in patients suffering from chronic disseminated candidiasis (CDC). Since CDC appears to share several features with immune reconstitution inflammatory syndrome, which has been effectively treated with CTC (French et al, 2004; Singh et al, 2005), it was hypothesized that the treatment would also be beneficial on CDC. The study reviewed the medical files of 6 adult and 4 minor leukemia patients who had CDC and were treated with CST. After a conformed diagnosis of CDC, patients were given age appropriate doses of CST in association with systemic antifungal therapy. The end point of the study was determined when all symptoms associated with CDC had been resolved. CST was administered for an average duration of 124.9 days and the findings of radiological analysis returned normal after a mean of 107 days. Clinical symptoms disappeared as early as 1 day. While the disappearance of clinical symptoms was resolved in record time in contrast to historical average exceeding 4 weeks (Thaler et al, 1988; Sallah et al, 1999 and Blade et al, 1992), the radiological abnormalities disappeared at around the same time as the historical average of 100 days (Kauffman et al, 1991). Based on these findings, the authors conclude that since clinical symptoms disappear so quickly, treatment for leukemia can be started earlier, thus giving timely treatment to the patients.

Strengths of the Paper

The study tries to find a way to cure CDC faster so that treatment for leukemia can be started without much delay. Not much research has been done in this area although several earlier studies have pointed out that the presence of CDC negatively impacts survival of leukemia patients (Anttila et al, 1997; Haron et al, 1987). Thus the paper tries to fill a gap in the existing research on this subject. The authors selected patients in five different hospitals and spread over a period of fifteen years, thus ensuring that the results were truly representative. All age groups, including children were included in the study. Also a wide spectrum of tests including biological, microbiological, radiological and liver biopsy was used to accurately diagnose CDC. The paper also notes in details patient characteristics before and after the onset of CDC, and the exact time gaps between the various occurrences such as onset of CDC and its cure. The authors also follow-up the patients over several years following treatment to ensure that there is no relapse and that the treatment has had desired impact. However, their conclusion that CDC must belong to IFI-induced IRIS seems to be without much support.

Weaknesses and Suggestions for Improvement

Although the study shows that CST can cure clinical symptoms of CDC as early as one day, the symptoms of the disease remain for an average of 100 days. The study does not discuss the implications of this and how it may adversely impact the patients. Also, the authors mention a higher median survival rate of 40.8% than historical rate of 26%. This implies that the increased survival rate is a direct result of CST treatment. However, the authors have neither provided the data nor tried to substantiate this claim in any way. The higher survival rate could be due to any number of reasons which have not been studied. The earlier study had taken place at a time when many of technologies now available were not available. The paper should have carried out a comparison of the treatment given in the historical study to the present treatment before making the claim.

Also, in the discussion, it is mentioned that since CDC responded to CST treatment it must belong to IFI-induced IRIS. This statement has not been properly explained and seems like the authors are jumping to an unwarranted conclusion.

Further Studies

Overall, the study comes up with a treatment for CDC which would help patients get treatment for leukemia in time and thus prevent unnecessary deaths. This will definitely benefit many patients. However, Further study needs to be carried out on the nature of CDC to understand the cause of this disease so that it can be completely eradicated in a shorter time than the present average of 100 days.

Apicomplexa

Kafsack BF, Pena JD, Coppens I, Ravindran S, Boothroyd JC and Carruthers, VB. (2009). Rapid membrane disruption by a perforin-like protein facilitates parasite exit from host cells. Science. 323(5913): 530-533.

Summary of the Paper

The aim of the paper is to study the role of Toxoplasma perforin-like protein 1 (TgPLP1) and understand the mechanism which helps the parasite Toxoplasma gondii egress the host cell at the end of its growth period. Toxoplasma is among the organisms that have perforin like protein (PLP). Proteins in this domain, known as the Membrane Attack Complex Perforin (MACPF), induce cell death by oligomerizing on the surface of target cells and inserting to form large pores (Pipkin and Lieberman, 2007). The MACPF domain of TgPLP1 is very similar to MACPF domain of mammals, bacteria and protozoa and exhibits core sequence which is very important for pore formation. The toxoplasma genome contains two MACPF gene (plp1 and plp2). However, plp2 does not express itself. The authors deleted the plp1 gene thus preventing the expression of TgPLP1 in plp1ko. While in malaria, similar genetic modification failed to have any impact, in Toxoplasma, absence of TgPLP1 meant that at the end of its 48 hours growth period, the parasite was unable to egress from the host cell. When mice were infected with plp1ko an wild type (WT) pathogens, those infected with just 10 WT tachyzoites died within 15 days while those infected with up to 1 million plp1ko tachyzoites survived. Based on the study, the authors conclude plp1 is responsible for parasite egression and that unlike in malaria, despite the presence of TgPLP1, the mechanical disruption of the parasitophorous vacuolar membrane (PVM) and host cell plasma membrane (HPM) is due to gliding motility and not due to pore formation.

Strengths of the Paper

The paper brings out an important difference between malaria and toxoplasma parasites, a parasite which causes congenital birth defect, ocular disease and encephalitis in immunocompromised individuals (Montoya and Liesenfeld, 2004). The genetically modified Toxoplasma are compared to the wild type and to Toxoplasma with slightly below normal expression of TgPLP1 (plp1ko/PLP1myc). These comparisons made it clear that the plp1 gene is responsible for helping the parasite egress the host cell. The experiments on mice proved that plp1 gene is affects the virulence of the parasite. Also, unlike in malaria, it is not the pore formation but the gliding motility which aids the egress and kills the host cell. However, the paper remains silent on what causes death of the organism.

Weaknesses and Suggestions for Improvement

While the experiment showed that TgPLP1 compromised the integrity of the membrane of the host cell, it was unable to explain the mechanism by which this happens. The study shows that the absence of plp1 gene makes it difficult for the organism to egress the host cell. It also shows that gliding motility instead of pore formation helps the parasite egress. But it does not explain how the integrity of the host cell is compromised and how gliding motility compromises the cell membrane. When the plp1 gene was absent, the parasites still tried to egress by prodding and deforming the membrane, they were not successful but the WT tachyzoites faced no resistance. The paper fails to explain, or tries to understand the chemistry behind this failure to egress. We do not know the chemical or biological changes that take place which prevent the parasite from egression in the absence of plp1.

The paper also does not discuss the implications of their findings. There is no mention of how future researches may be able to benefit from this experiment or any advice for future research. The final conclusion stating that a protein analogous to TgPLP1 could be responsible helping malaria parasite egress from infected erythrocytes is entirely unsubstantiated and should have been discussed in more details.

Finally, authors make use of many pictures and graphical representations to explain their experiment but some of these pictures are not very clear. For example, figure 3A tries to show pore formation but nothing is visible in the pictures, despite the authors having marked them clearly. The authors could have supplemented these pictures with diagrams to give a better understanding of the procedures.

Further Studies

The paper identifies the role of TgPLP1 in Toxoplasma, though it remains silent on how this fact may be exploited. Future studies could investigate the implications o the findings of this paper and could even try and search for ways to reduce the virulence of toxoplasma so that infected individuals could be treated. Also, the role of PLP in malaria parasite could also be studied in details to substantiate the authors suggestion that PLP in malaria would have a function analogous to TgPLP1.

References

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