HURJ Spring 2009 Issue 10
Biotechnology
Table of Contents spotlights: 4
Groundbreaking Research in Neuroscience lucas brambrink
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The Changing of the Guard paul grossinger
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Demography of Reproductive Health jeremy stein
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Chemical and Biomolecular Engineering with AIChE/SBE krystina laucik
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Students for Choice kathryn mercogliano and amy peyrot
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A Small Journal with Big Plans lindsay van thoen
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How Big Things Come in Small Packages michael lou
spring 2009 focus: Biotechnology 17
Seeds of Promise ayesha afzal
20 Stem Cells: Discovery about the Influence of Microenvironments and Remaining Obstacles leela chakravarti 23
Is HDL Really the “Good Cholesterol�? nezar alsaeedi
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Letter from the editors On behalf of the staff, we would like to welcome you to the Spring 2009 issue of the Hopkins Undergraduate Research Journal (HURJ). Since its inception in 2001, HURJ has evolved each year to encompass and reflect the diverse interests of Hopkins undergraduates. This issue’s focus on human rights is the latest in a trend of previous focus topics dedicated to important concerns of today. We found fellow undergraduates to be incredibly responsive to this theme—the result is a journal of many voices, opinions, and ideas. In this issue, HURJ showcases two types of articles. Spotlight articles highlight the achievements of professors and students. We are also excited to share with you the work of student groups on campus. Focus articles written for this issue build on this existing framework, adding dimension and insight to the continuing discussion of current and future biotechnology. Whether our writers are pursuing in-depth analyses of stem cell potential in the cellular world or an analysis of HDL cholesterol, each article is profoundly interested in inspiring solutions. We are proud of our writers and staff and hope that you will honor their work with your attention. This issue of HURJ would not have been possible without the dedication and support of the HURJ staff, Hopkins faculty, and HURJ sponsors. We would like to thank the students and professors who contributed to HURJ either through sharing their unique experiences, reviewing articles, or researching topics. We would also like to thank the Hopkins Student Activities Commission and the Office of Student Involvement for their generous contributions and continued support. Finally, we thank the Digital Media Center for allowing us the use of their facilities and equipment. As always, we welcome your ideas, comments, and questions. May this journal serve as inspiration for you to begin your own project and contribute to the intellectual growth of this community. Editor-in-Chief of Operations
Editor-in-Chief of Content
HURJ 2008-2009 Editorial Board: Editor-in-Chief of Operations
....................... Adam C. Canver
Editor-in-Chief of Content
....................... Ishrat Ahmed
Editor-in-Chief of Layout
....................... Sharon Ovadia
Spotlight Editor
....................... Jeremy Stein
Focus Editor
....................... Johnson Ukken
Engineering Editor:
....................... Karun Arora
Science Editor:
....................... Karun Arora ....................... Michael Lou
Humanities Editor:
....................... Cuong Nguyen
About HURJ:
Sidebar Editor
....................... Raja Vallarapu
Copy Chief
....................... Lindsay Van Thoen
Public Relations Officers
....................... Adriane Alicea ....................... Michael Lou
HURJ Staff: Focus Writers
Ayesha Afzal Nezar Alsaeedi Leela Chakravarti
Spotlight Writers
Lucas Brambrink Paul Grossinger Krystina Laucik Kathryn Mercogliano Amy Peyrot Jeremy Stein Michael Lou
The Hopkins Undergraduate Research Journal provides undergraduates with a valuable resource to learn about research being done by their peers and interesting current issues. The journal is comprised of three sections- original research, a current focus topic, and student and faculty spotlights. Students are encouraged to contribute their work either by submitting their research, or by writing for our focus or spotlight sections. The tremendous interest in our focus section has necessitated the use of an application process for our writers, while our research and spotlight sections are open for all to contribute to.
Disclaimer: Copy Editors
Haley Deutsch Miriam Haviland Xuan Huang Lisa Rosinsky
Layout Editor Wenning Xu
The views expressed in this publication are those of the authors and do not constitute the opinion of the Hopkins Undergraduate Research Journal.
Hopkins Undergraduate Research Journal Johns Hopkins University Mattin Center, Suite 210 3400 N. Charles St. Baltimore, MD 21218 hurj@jhu.edu http://www.jhu.edu/hurj
Gr ou Re nd Ne se br ur ar ea os ch kin ci in g en ce
Lucas Brambrink / HURJ Staff Writer
With the revolution of molecular biology, research in biology flourished. New, ground-breaking papers were published; from these discoveries, our understanding of life at its deepest level grew enormously. Along with this expansion of knowledge came a shift in the scientific strategy of inquiry: with new technologies, it was possible to examine life at its deepest, ‘nonliving’ level (the molecular level). It was thought that through analysis and organization of this information, humanity would attain a fundamental, comprehensive understanding of life itself. Dr. Stewart Hendry, a professor in the department of neuroscience at Hopkins, devoted his career to this concept. Dr. Hendry carries out his research by using the innovative analytical techniques developed in the wake of the revolution in molecular biology. Because of its status at the forefront of modern technology’s application in the sciences, molecular studies have had groundbreaking success throughout all biological disciplines. The theoretical approach of molecular studies is simple: it posits that precise knowledge of the infinitude of molecular processes translates into a greater understanding of the collective level. As modern technology has provided cutting edge methods and unprecedented infallibility, this innovative approach has correspondingly birthed foundation-altering insights in the life sciences, particularly in the fields of genetics, biochemistry, and most prominently, neuroscience. Obtaining a comprehensive understanding of the brain’s molecular workings is a task so immense in both breadth and complexity that only the arduous work of generations will be able to approach completing it. Therefore, the vanguard of current molecular neuroscientific research is comprised of countless research teams working simultaneously, each exploring highly specific aspects of neuroscience. Applying these ideals to their own research, Dr. Hendry and his team focused on the molecular processes underlying visual perception, particularly the connection between the retina and early visual cortical areas of the brain. Our understanding of the
molecular pathways starting from the initial process of photon absorption all the way to visual cognition has undergone dramatic redefinition in the last couple of decades, providing an exciting opportunity for discovery for modern scientists. Dr. Hendry analyzed the presence of a certain postsynaptic enzyme, type II Calmodulin-dependent protein kinase, in the Lateral Geniculate Nucleus (LGN—the brain’s primary processing center for raw visual information) found in the thalamus. Studying the thalamus of Rhesus monkeys, Dr. Hendry found that a key functional section of this enzyme, its ‘alpha subunit’, was expressed only in a particular group of neurons, referred to as koniocellular cells. This information pointed towards a stark functional and neurochemical difference between these particular cells and their surrounding cells. Prior to Dr. Hendry’s findings, visual information was thought to be communicated by only two populations of retinal ganglion cells through two sets of layers in the LGN, which then carried the information to higher cortical areas. This model proposed two parallel pathways for visual information to the brain. However, Dr. Hendry was able to interpret the data obtained by his own research, in combination with data from outside research, to conclude that instead of two pathways, there exist at least five (most likely more) visual pathways in primates. The latter three pathways are perpetuated by the previously mentioned koniocellular cells, which themselves are further functionally differentiated into dorsal, middle and ventral layers. These cells, connected to blue (S) photo receptors, form independent and functionally distinctive pathways for visual information. These findings demanded a reinterpretation of our current understanding of the way in which we process our visual surroundings: the presence of anatomically separate and physiologically distinct pathways suggests significantly greater use of parallel processing by the brain than previously thought. After having published these findings and thus reshaped our understanding of the early visual system, Dr. Hendry is continuing to work on these
visual pathways, particularly in respect to their role in Alzheimer’s disease. It has been observed that Alzheimer’s patients lose their ability to distinguish between colors of shorter wavelengths, a condition called acquired tritanopia. Since the retina of Alzheimer’s patients did not show any abnormalities, it points towards a problem in later visual processing within the brain. Upon further investigation of this hypothesis, Alzheimer’s patients have indeed demonstrated a notable degeneration in koniocellular cells. As it has been established that blue visual information is processed by the physiologically distinct koniocellular cells, it follows that those cells are more susceptible to the neuro-degeneration induced by Alzheimer’s disease. Hence, Dr. Hendry is currently working to find what aspect of their physiology raises their susceptibility to Alzheimer’s disease. Answers to this question could potentially lead to revolutionary insights into the molecular processes of Alzheimer’s disease in general, as well as the development of prevention techniques and possible cures. Dr. Hendry truly integrated the epistemological principles of molecular biology into his research career. Dr. Hendry initially refined our understanding of the visual pathway, and then studied his findings’ implementation on the collective level, particularly in pathology. After decades of outstanding research, Dr. Hendry continues to pursue knowledge on the forefront of neuroscience.
The Changing of the Guard:
What Obama’s Presidency Means for the Middle East
Paul Grossinger / HURJ Staff Writer For the last eight years, President George W. Bush has transformed American foreign policy to reflect his belief in neoconservative interventionism. This change was, regardless of one’s political views, transformative for the United States. However, with the return of the Democratic Party to power in Washington, this purely neoconservative era seems to be at an end. As such, this historic transfer of power begs for an analysis of what changes we can expect in US policy towards the Middle East. Professor Waleed Hazbun of the political science department is currently working on such an analysis. His review essay, “Beyond the Bush Doctrine,” details his views both on the Bush doctrine itself and on the prospects for change with Barack Obama’s election. In his work, he explains that, while the stated goals of US policy in the region may be articulated differently, “crisis management, rather than ideology, will likely shape most of his policy choices.” This is because, according to Hazbun, “the current posture of the US administration limits the tools the Obama administration will have to address future crises.” According to the professor, this last point was the crux of the issue. George Bush’s neoconservative agenda led to actions, in particular the invasion of Iraq, which went far beyond any of the interventions in the region conducted by past administrations. However, despite its transformative nature, Hazbun stressed that the invasion was actually a logical consequence of the actions of the previous two administrations. George Bush Sr. had launched an international coalition that threw Iraq out of Kuwait yet decided not to topple Saddam Hussein’s government directly. Clinton, his successor, had used airpower, sanctions, and covert action to topple the Hussein regime; a policy which had very publicly failed by the onset of Bush’s tenure. Therefore, when the current president took office, nearly every option short of direct attack had already failed in the Iraq theatre, so his decision to invade, while still a “seismic leap” according to Hazbun, was nevertheless a move that reflected the natural progression of US pol-
icy in the region at that time. Though Iraq was, as the President-elect often states, a unique situation and an error in judgment by our government, to the Professor it provides a lens from which to analyze how the Obama administration will or will not alter US policy as it relates to the various issues facing the Middle East. As regards Iran, Professor Hazbun sees only two real policy options for the US: reject increased Iranian influence and escalate tensions over the Iranian presence in Iraq, or strike what could be termed a “Grand Bargain” where the US and Iran would put aside their differences and reorder the region together. However, as the US has spent the past five administrations, both Democrat and Republican, aligning itself and the region against increased radicalization (which would come with increased Iranian influence), such a ‘Grand Bargain’ seems unlikely. The possibility of change to US policy towards the Israeli-Palestinian peace process and Afghanistan are both hindered by the dearth of options available as a result of US actions over the last decade. Regarding the former issue, because George Bush largely ignored the crumbling Clinton peace efforts in his first term, the US lost its position as the main bargainer between the two powers, and would need to show an extraordinary degree of open-mindedness in the area to regain it. As to the latter, the Professor laments the fact that Obama seems to advocate an escalation of the conflict in Afghanistan rather than using it as a platform to explore new ways to reach hostile elements in the region and de-escalate the military aspect of the war on terror. This is not to say that the Professor is entirely pessimistic about the inertia of US policy. In our interview, he made a point of explaining that the neo-conservative doctrine of forcing change “from outside” rather than fostering internal progress will be abandoned. This is, in Hazbun’s eyes, positive and will likely lead to an increase in dialogue with various groups. Though not a reversal of US policy of the magnitude that some would like to see, it is at least a start.
Demography of Reproductive Health Jeremy Stein / HURJ Editor Professor Stanley Becker, of the Johns Hopkins School of Public Health Studies, specializes on demography and reproductive health. Particularly, he focuses on couples counseling and education to encourage family planning and stop the spread of HIV. Currently, Professor Becker is teaming up with officials from the Grameen Bank in Bangladesh in order to determine how micro-credit and health packages affect family planning, economic well-being and women empowerment. He hypothesizes
that a combined package of health services and micro-credit will have a greater effect on each area than if the programs were separated. The experiment is still ongoing. Also in Bangladesh, Professor Becker has attempted to educate males in Bangladesh about the benefits of receiving a vasectomy. A vasectomy is a surgical procedure where males are sterilized. It is much safer than tubal ligation, a method of female sterilization. Professor Becker asserts that sterilization is important because of overpopulation in many countries, especially Bangladesh. If the population can reach about 2 births per family, as Professor Becker states, then families can give their kids a better life. Moreover, smaller families would more likely lead to economic development. In the United States, Professor Becker worked with Planned Parenthood in Baltimore to determine the effects of couple counseling on women. Professor Becker realized that most women were not aware that the option of couples counseling was available. The women who underwent couples counseling were comforted because their husbands were able to support them in their difficult decision to have an abortion. Professor Becker asserted that the use of couples counseling will lead to an increase in contraceptive use after a woman has an abortion. In sub-Saharan Africa, Professor Becker determined ways to guarantee safer births. In his experiment, he found that community education reduced neonatal and prenatal mortality because the locals learned that keeping the baby warm, using a clean blade and washing hands increased the chances of infant survival. Professor Becker hopes that more Africans will be educated about basic health in order to diminish the infant mortality rate. In another study in Sub-Saharan Africa,
Professor Becker found that couples counseling was an effective measure to stop the spread of HIV. When the HIV-infected woman fails to tell her husband about the disease, they will more likely have unsafe sex which can lead to the husband transacting HIV. A woman is often afraid to tell her partner because she is afraid that he will beat her. Professor Becker believes that couples counseling provides a secure environment for the man to learn about the woman’s HIV and take the necessary preventive measures. Professor Becker has helped save countless lives, whether through limiting the spread of HIV or encouraging measures to reduce infant mortality. Here at Hopkins, Professor Becker continues to inspire students to devote their lives to improve health and increase health awareness in every part of the world.
club spotlights Chemical and Biomolecular Engineering with AIChE/SBE Krystina Laucik / HURJ Staff Writer Johns Hopkins’ AIChE/SBE is a professional academic group on campus that combines the American Institute of Chemical Engineers (AIChE) with the Society of Biological Engineers (SBE). Although the majority of our members are Chemical Engineers, we are an open society for anyone on campus interested in learning more about chemical and biological engineering. AIChE/SBE strives, through its events and activities, to give members access to our resources, which in turn help facilitate relationships amongst the students, faculty, and the outside world. Our mission is to embody our slogan, which this year is “Participate, Connect, Grow!” To further this mission, AIChE/SBE organizes numerous social and industrial events throughout the semester. On campus, we host Ice Cream Socials, Game Nights, and Mentor/ Mentee Mixers to promote interaction amongst the students in our group. There is also an annual Bert’s Night, where students can dine with engineering professors and get to know them outside the classroom. For those who are interested in graduate school, we have Q&A Panels with graduate students from the chemical and biological engineering departments to answer questions on a wide range of subjects. We also sponsor a Chemical Engineering Car Team that competes each year in the Spring Regional Conference. This important opportunity allows undergraduates to exercise what they learned in the classroom to a hands-on project. AIChE/SBE is also geared towards preparing 10
its members for life after college. Four years of college can go by extremely quickly, and as a member of AIChE/SBE, you will have a wealth of resources connecting you to the outside world. We frequently host industry representatives from top companies such as W.R. Grace, Exxon Mobil, Merck & Co. and many others to allow students to gain more knowledge and networking opportunities. Becton and Dickinson, a company located only about a half hour away from Homewood campus, also allows us to come in for a Plant Facility Tour, where interested members can visit a real industry setting, learn about break-through technology, and talk with men and women active in engineering industry. In addition, AIChE/SBE works with both the Career Center and HCCN to promote awareness for job opportunities and to provide seminars to strengthen important interview and networking skills. If you participate as a member in AIChE/SBE, we guarantee that you will grow! Improve your resume, by being involved and potentially running for leadership positions on the board. Grow as an engineer, through our workshops and hands on interaction. Networking and making industry contacts is an invaluable benefit. Last but not least, grow as an individual. Participating and connecting with others as a member of AIChE/SBE requires you to step out of your comfort zone and reveal inner potential that you may not have been aware of. The benefits of Johns Hopkins’ AIChE/SBE are infinite. Join us. It’s never too late to start reaping the rewards.
Students for Choice Kathryn Mercogliano and Amy Peyrot / HURJ Staff Writers Students for Choice advocates for individual autonomy on reproductive health care, availability of the most medically-accurate information on reproductive health, and access to healthcare providers who respect each individual’s choices. Simply put, we believe in a person’s right to make decisions about his or her own body, and we believe that all decisions about sex should be well informed. Our mission is often oversimplified as being “the abortion group.” That is a misnomer; reproductive health issues affect every person, regardless of individual beliefs on abortion. Our pro-choice principles encompass many reproductive health issues. To be pro-choice is to respect the individual circumstances that lead others to make decisions that may be different from your own, just as you would expect others to respect your choices. Regardless of individual beliefs about the morality of abortion, we at Students for Choice are committed to a woman’s right to have a safe abortion. We believe in this right for two main reasons. Firstly, abortion bans do not stop abortions. The National Abortion Federation estimates that 1.2 million women per year obtained illegal abortions before Roe v. Wade legalized abortion in 1973. Illegal abortions endanger the lives of women who seek them. The Guttmacher Institute notes that 200 women died from complications of illegal abortions in 1965; these accounted for 20% of all deaths of pregnant women. These 200 deaths were the only ones conclusively linked to illegal abortion (through admission before death or acknowledgement by family members) ; the true number is likely higher. Secondly, we believe that individual beliefs on the morality of abortion are private, personal views that
cannot be imposed upon a democratic society. One of the foundations of American democracy is the doctrine of separation of church and state; the questions of morality on this issue must be resolved between individuals, their spiritual leaders, and their doctors. Students for Choice recognizes that much debate has been centered on the question of the beginning of life, and wholeheartedly embraces the choice of parenthood. However, parenthood must be a voluntarily chosen state. Endowing a fetus with all of the rights of a living human being is an unfair dismissal of the rights of the woman who must nourish its potential. The choice to become a parent is the first responsible decision that can be made on behalf of a future or potential child. A parent has a tremendous responsibility for his/her child. Women who know they are not physically, mentally, emotionally, and/or socially prepared to have children are entitled to make a personal decision without outside interference precisely because they will bear the burdens of whatever choice they make. Students for Choice strongly supports access to all reproductive services and comprehensive sexual education for students at Johns Hopkins. Our group is not only committed to ensuring the legality and availability of abortions; the need for abortions can be greatly minimized by greater availability and affordability of birth control methods, as well as comprehensive age-appropriate sexual education. Our on-campus activities strive to involve the student body in education about safe sex and a healthy reproductive life. We encourage every reader to look at our website at www.jhu.edu/choice for information about birth control, STI testing, prenatal care, and abortion services in the Baltimore area.
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A Small Journal with
BIG Plans:
Foundations, Johns Hopkins’ Undergraduate Journal in History
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Lindsay Van Thoen / HURJ Editor An interview with Ersin Akinci, senior and Editor-inChief of Foundations, Johns Hopkins’ undergraduate journal in history. Foundations, which was established in 2005, publishes biannually online at www.jhu.edu/ foundations. When/Why did you first become involved in Foundations? I first became an editor at Foundations in my sophomore year, and have been Editor-in-Chief for the last two years. I joined because I believe an academic journal’s goal is very noble—we’re publishing original historical research, which gives insight not only into times past but our own, as well. In that way, there was a seriousness to Foundations’ mission that appealed to me. Also, undergraduate history publications are not very common, and yet there are always undergraduate history majors who have papers worthy of publication. It would be a shame not to have a venue for that. Who writes the articles that Foundations publishes? Foundations receives submissions from undergraduates all across the world. Recently we’ve been trying to build strong personal ties with departments from top national and international universities, so that more professors and students are aware of the opportunity to publish their research. We’re also reaching out to non-history departments in order to broaden the scope of our journal and make it more interdisciplinary. Why is being interdisciplinary important to Foundations’ mission? We can’t compete with professional academic history journals in terms of depth, simply because no undergraduate has the training or experience to conduct the same kind of long-term research professional scholars do. But what we can do is enliven the discussion of historical research by bringing out unusual subjects or combining various approaches to a topic in an unorthodox way. Among the more interesting submissions, for example, we’ve received a history of graffiti in Chicago and a study of the US Presidential election of 1872 written through the perspective of an election souvenir. When you’re an undergraduate, and not necessarily committed to a definite niche in a particular field, you’re more willing to experiment and draw connections across different fields of enquiry. This can result in a lot of
really creative work. How do you decide which papers Foundations will publish? Foundations has of an editorial board made up of Hopkins undergraduates that makes all publication decisions. Most editors are history majors, but we have editors that come from all backgrounds. We also have a Faculty Advisory Board that gives their professional opinion on the articles, though ultimately the decision of what to publish is based on the opinions of the editors. Foundations recently published its Fall 2008 issue, which was its first issue since 2006. Can you speak to that? This current issue has been a long time in the making. As a relatively new journal, we’re just beginning to build a more established presence on Hopkins campus and abroad. It took us a while to get a sense of the right procedure for choosing and publishing articles. For the Fall 2008 issue, we received over eighty submissions and published only three, along with two staff-written book reviews. We received some great papers, and we were very proud of the quality of the research that we ultimately published. We also took the time to setup a new online edition to complement the print edition of Foundations (http://www.jhu.edu/foundations). Not only is online publication the wave of the future for journals, but it’s also the best way for a journal with a limited budget like ours to reach as many people as possible. We hope our website also will also provide a forum for historical discussion and debate, because you can write and read comments on the articles. Finally, how do you see Foundations growing in the future? I would hope that Foundations’ reputation for high-quality research continues to grow both nationally and internationally. I see Foundations as leading the way in terms of the quality of the papers we publish, and setting a standard for other undergraduate journals to look up to. Also, I hope that the serious academic research that our journal publishes will enhance undergraduates’ engagement with humanities research. Foundations has always had a strong commitment to expanding and deepening the level of historical debate and awareness among undergraduates, and I can only hope that it will continue to do so in the future. 13
How Big Things Come in Small Packages: The marvel of Drosophila genetics and how it unravels the secret of neural signaling pathways
Michael Lou / HURJ Editor
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Ever since the days of pioneering geneticist Thomas Hunt Morgan, fruit flies have become an invaluable asset to anyone who conducts research on biological systems. Only recently, however, has the potential of Drosophila research in neural signaling been realized. In evolutionary terms, sensation and perception are extremely important to an organism’s ability to adapt and assess the environment around them. Yet, current scientific knowledge offers
only a peripheral view of how genes and neural circuits are integrated into an organism’s ability to sense. Nobel Prize laureate Eric R. Kandel’s decades-long research involving the biochemical changes associated with neurons in the development of sensation and perception had a resounding impact on the scientific community. This eventually led to the conclusion that fundamental changes in genetics and henceforth gene
expression could affect an organism’s ability to relay neural signals. In correlation, a suitable animal model had to be found. In many ways, Drosophila melanogaster was the ideal animal model for this kind of research. The species had a reasonable reproduction rate, making research assessments across several generations possible within a matter of weeks. Fruit flies are significantly lower maintenance than their counterpart mammalian models such as the laboratory clichéd M. musculus. Fundamentally, the genetic structure of fruit flies allows efficient manipulation with ways for investigators to visually observe the effects of induced genetic changes. A significant portion of D. melanogaster neural research involves Class II DNA transposons, from which segments of DNA termed P-elements are cut using transposases and later inserted randomly back into the genome. Pelements are widely used as a mutagen that involves an autonomous immobile element and a nonautonomous mobile element. The theory involved is quite complex and will not be discussed here. The main importance of P-elements is their invaluable contribution in making transgenic flies by promoting viable means of introducing genetic elements into the organism’s genome. Furthermore, Pelements may also carry a secondary gene used to identify the progeny of interest in the form of a visible marker such as eye color (red, YW) that is used in conjunction with the P-element insertion. The obvious result is that the transgenic flies will have the desirable phenotype and investigators can then visually screen genetic stocks and identify these gene carriers with relative ease.
Cross breeding mutant D. melanogaster strains are another common technique utilized in the laboratory. The underlying molecular basis for this technique stems from the fact that male fruit flies do not undergo crossing over in the initial stage of meiosis. Naturally, this eliminates potential for further genetic scrambling in the male parental chromosomes during the process of meiosis. Furthermore, within the fruit fly genome, chromosomes termed “balancers” prevent these chromosomes from crossing over with their homologues during meiosis. Balancer chromosomes are useful in this manner in that they carry one or more dominant markers, which are then used to identify the progeny of interest resulting from a genetic cross. Modes of control exist in that the balancers affect the reproductive fitness of the progeny by coding for lethal homozygous combinations. In this manner, genetic markers are prevented from complete chromosomal recombination after crosses. In summary, the genetic structure of D. melanogastor offers multiple successive genetic controls that an investigator can actively exploit to create different genetic variations. Pain signaling is an active area of research in which multiple recent breakthroughs have been made utilizing the D. melanogaster animal model. Inciting particular interest are the specific substance aversion behaviors commonly recognized in D. melanogaster larvae. Third instar larvae (directly before pupation) show significant aversive behavior towards fructose mediums whereas the same larvae elicit no definitive response when placed on sorbitol or lactose mediums. “The D. melanogaster genome encodes a single member of the mammalian Neuropeptide
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Y family (NPY), Neuropeptide F (NPF).” The NPY neurotransmitters in mammals play a critical role in maintaining homeostasis as well as regulating responses to noxious external stimuli. A particular experiment investigated this aversive behavior and how in the case of D. melanogaster, it facilitates further development. Evidence provided suggests that D. melanogaster has a fructose-specific chemosensory pathway of which the painless (pain) ion channel (TRPA) is crucial for a fructose stimulated response. Furthermore, the developmental switch responsible for fructose aversion is regulated by NPF. P-element insertions were then used to create the hypomorphic genetic strains noted as pain1 and pain3, of which larvae with mutant pain alleles show significantly reduced fructose aversion. An additional transgenic study was done as well. The GAL4-UAS (upstream activation sequence) is a useful mechanism to drive overexpression of transgenes. In this circumstance, a “paingal4 driver allele containing a GAL4 coding sequence directly downstream of the pain promoter was crossed with a UAS-shibire temperature sensitive semi dominant negative of dynamin that can block neurotransmission at temperatures greater than 29 degrees Celsius.” The resulting offspring from the genetic cross showed decreased levels of aversion to fructose at 30 degrees Celsius. Fundamentally, this suggests strong evidence that the pain (TRPA) receptor is responsible for the decrease in sensitivity associated with fructose aversion. Additional conclusion of NPF activity suggests that NPF “acts as an end effector of a temporal module that may suppress PAIN (gene regulated) channel activity”. This study provides an excellent example of how neurotransmitters as well as ion channels can be easily manipulated using the tools provided by the versatile nature of the Drosophila genome.
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Calcium ion channels play an important role in the signal transduction process due to the importance of calcium as a secondary messenger. Significant portions of research are devoted to these channels termed transient receptor proteins. A well known area of study investigates Na/Ca exchangers utilizing mutant flies in the process. The Drosophila encodes three exchangers one of which is the CalX gene, all three of these exchangers are crucial to phototransduction through heterotrimeric G protein coupling. This particular experiment utilized highly specific chemically induced mutations through ethylmethylsulfonate (EMS) instead of the P-element process. It was shown that the induced mutations on CalX had significant effects on the mutant flies’ phototranduction process. The CalX gene encodes for two proteins CalX1 and CalX2, which differ by only five amino acids. In order to indicate that mutations on CalX were indeed responsible for the differences in transduction observed, a wild type version of the CalX gene was introduced by fusing the CalX1 and CalX2 genomes with a noxious stimulus promoter sequence. Fly lines with these two constructs present were then crossed with the mutant backgrounds and upon introduction of heat shock treatments, enabled restoration of a visual response under further assaying procedures. The most prevalent theme of neural signaling research in fruit flies involves inducing a specific mutation and later restoring or isolating that mutation through an extremely versatile genetic cross. Fruits flies have proven time and time again to be a valuable asset to investigators on a fundamental molecular level. It is extremely likely that many important discoveries will be made in the near future regarding neural signaling with fruit flies playing an essential role.
Seeds of Promise Agricultural Biotechnology and the Fight Against Hunger Ayesha Afzal / HURJ Staff Writer Of the six billion people in the world, more than 1 billion live on less than the equivalent of US$1 per day, and another 2 billion live on less than US$2.1 Further, about 800 million of the people living with chronic hunger live in developing countries, where food scarcity is so high that performing the necessary daily tasks of living becomes impossible. Food is not only essential to life but for many it also expresses cultural, religious, and even political visions of society. Solving the problem of food shortages in these countries will not only provide the people with means to survive, but it can also have positive consequences in helping to improve the infrastructure of developing countries. Creating positive social change will allow people to reject current political regimes in their country and further will propel forward the political vision of democracy in these traditional societies. Once social change begins, the process, if successful, has the power to push for the political change needed so badly in the developing countries. The fight against hunger is not a new one, and yet it still remains a huge problem. However, there is hope that this problem can be solved through the use of technology. One successful example of the use of technology to increase food supply in less developed countries is the Green Revolution. The Green Revolution first began in Mexico in 1945, when politicians, confronted with the problem of a growing population and increased food shortages, invested heavily in research on different types of wheat. Using different genetic combinations that would be more resistant to multiple weather climates, they were able to transform agricultural research and develop more varieties of wheat such that Mexico was able to provide food for 30 percent more of its population. 2 The success of the use of biotechnology in Mexico suggests that it can
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revolutionize the agricultural sector in other developing nations throughout the world. According to economist Magriet Caswell, social change is always “induced by the introduction of any new technology and the individuals that benefit from biotechnology may not be the same as those who bear the costs.”3 There is a debate between those who see the use of biotechnology as a necessary solution to feeding the world’s growing population, and those who are more wary of the potential long-term effects of its use. This debate, as stated by the Organization for Economic Cooperation and Development (OECD), “has been underway for over 15 years, though discussion on genetically engineered foods has intensified within many countries more recently.” Scientists at this time simply do not know enough about potential harmful health effects with regard to genetically modified crops and wish to exercise extreme caution before introducing agricultural biotechnology on a global scale. However, the economic benefits give compelling arguments that serve to strongly advocate the use of agricultural biotechnology. One of the positive economic effects of agricultural biotechnology is that it will allow developing countries to limit their dependence on a farm-based economy. The development of this technology will “contribute to the trend toward few and larger farms.”4 The implication here is that decreasing the number of farms will free up resources currently tied to farming, including labor and land. These resources, once freed up, could be used in sectors unrelated to the farming industry, such as the mechanical industry. Economically speaking, having large, specialized farms is a more effective, efficient strategy where, with fewer workers and less land, enough food can be provided for the whole country.
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Thus, the production of goods by large farms would lower the production cost of the goods. Farmers could therefore charge cheaper prices for the good and still receive a profit. Further, since more consumers would be able to afford the good, farmers would yield more profit than before and have further incentives to provide the population with low-cost goods. Thus, not only would the population of less-developed countries have to pay less for food, the farmers providing the goods would also be better off. If the populations of less-developed countries are successfully able to increase the money they spend on food, there will also be a positive impact on the environment. Currently, “environmental degradation can be seen across the globe from the expansion of deserts in Africa and Asia….the result due to overgrazing and inappropriate arable cropping.”5 Environmental degradation exists in large part due to ineffective planting methods and the need for food outweighing concern for farming techniques harmful to the environment. However, using new cropping systems “based on novel crop varieties with traits such as drought tolerance and increased pest and disease resistance” would successfully “achieve substantial increases in the productivity without further degrading the environment.”6 This method, made possible by agricultural biotechnology, would help stop the destruction of the environment and natural resources. As a result, it would be possible to produce a greater yield of crops, which would further help stimulate the economy. In fact, a point could be reached where the supply of crops grown would exceed the demand. Once developing countries have met the demand for food, they could turn their attention to other sectors that would make them more viable in the world market. Agricultural biotechnology increases a
plant’s resistance to herbicides, pests, and diseases, and in general, enhances the food quality of plants.7 Common nutritional deficiencies that remain the leading cause of death in infants would be eradicated as a result. Looking back to history, the argument can be made that introducing the bean into the diet of people in the medieval period allowed for the advancement of society. The protein in the bean gave people greater nutritional strength that led to a lower infant mortality rate, which meant families had more children to help out on farms. As a result, families could afford to send some children to school and with education now part of society, economic and social change was now possible. This argument shows an example of the importance that nutrition plays in a society and its advancement. Providing better quality, nutritious food to developing countries equips them with the tools necessary to industrialize, a key step needed for sustained economic growth. These arguments, nonetheless, remain hypothetical, since there is no long-term research on agricultural biotechnology. Thus, opponents of agricultural technology, or rather, those hesitant towards its use argue for the need of further experimentation and analysis to possible alternatives. Further concerns exist about action due to governmental regulations. Since biotechnology will eliminate the need for many farms, there is always the fear that developing countries governments’ might capitalize on this. Many of the governments of developing countries are corrupt and thus they could easily exploit the low cost of producing the crops by selling it to consumers for a higher price by monopolizing the agricultural
industry. Nonetheless, while this does remain a fear, the interest of organizations such as the OECD in helping less-developed countries provides a means to regulate such governments. Since developed countries dominate this technology, they can effectively take preventive measures to ensure that agricultural biotechnology is used as a means to end hunger and help improve the agricultural sector of lessdeveloped countries and not to increase the profits of greedy government officials.8 The key to the success of biotechnology will be driven by the reaction of consumers. Though there are many compelling reasons to further advance the research in biotechnology, the interest will not be there until there is clear-cut evidence of the willingness of consumers to purchase agricultural goods modified by biotechnology. The success of the Green Revolution shows that biotechnology has tremendous potential; all that remains is the question of whether or not countries are willing to take the step for change. Unfortunately, for many developing countries, this is not a feasible option until developed countries take a serious interest in ending the problem of world hunger. References 1. 2. 3. 4. .
.
1. 2.
World Bank, 2002 Organization for Economic Co-operation and Development (OECD): Agricultural Biotechnology 2002 Working Papers. p. vii Caswell, M. F. (2003). Agricultural Biotechnology. Hauppauge, New York, United States of America: Novinka Books. p. x Ibid P. 61 Biotechnology in Agriculutre Series: Persley (ed.). Biotechnolgy and Sustainable Development: Voices of the South and North. Cambridge, MA , United States of America: CABI Publishing. Contributor: Johnson P. 230 Biotechnology in Agriculutre Series: Persley (ed.). Biotechnolgy and Sustainable Development: Voices of the South and North. Cambridge, MA , United States of America: CABI Publishing. Contributor: Johnson P. 230 Caswell, M. F. (2003). Agricultural Biotechnology. Hauppauge, New York, United States of America: Novinka Books. P. 81 Press, F. (1985). President National Academy of Sciences to a Symposium on Biotechnology for Solving Agricultural Problems. (P. C. Augustine, Ed.) Biotechnology for Solving Agricultural Problems , 10. P. 399
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Stem Cells:
Discoveries about the Influence of Microenvironments and Remaining Obstacles
Leela Chakravarti / HURJ Staff Writer Due to recent advances in stem cell research, organ and tissue regeneration is becoming more of a reality than ever. Stem cell implantation can foster regeneration and renewal of organs because of a stem cell’s ability to renew itself and differentiate into other cell types. Regeneration of organs would essentially eliminate the need for full organ transplants, changing the way ailments such as cancer, muscular dystrophy, spinal cord injuries, heart disease, Parkinson’s disease, and many others are treated.1 Studies of specific stem cell types and their environments show that controlled implantation of engineered stem cells would make organ and tissue regeneration possible. Since the 1960s when Canadian scientists Ernest McCulloch and James Till discovered self-renewing cells in mouse bone marrow, research in the field 20
has evolved such that many groups are currently focused on finding solutions to the technical dilemmas associated with stem cell treatment.2 Various research efforts are underway to try to make implantation more successful by engineering the stem cells’ environments to support proper differentiation and to reduce the risks involved in treatment. Along with her research team, Professor Sharon Gerecht of the Johns Hopkins University Department of Chemical and Biomolecular Engineering conducts such experiments to determine precise methods of engineering stem cells’ microenvironments so that they will foster blood vessel formation. In 2008, Gerecht was awarded the American Heart Association Scientist Development Award for promising young scientists as well as the Maryland Outstanding Young Engineer Award for her work in
the engineering of stem cells. Her lab works with somatic (adult) and embryonic stem cells, which have slightly different qualities resulting from the types of environments in which they are found. Embryonic stem cells are derived from four to five-day-old embryos from eggs fertilized in vitro, or in the laboratory environment, and are totipotent; they have the ability to differentiate into many different specific cell types, such as blood vessels or nerve cells. Somatic stem cells, found in a specific tissue or organ, have the ability to differentiate but are generally not totipotent; they can usually differentiate only into cells of the tissue in which they are found. Somatic stem cells serve to renew or to repair the specific tissue.1 According to Professor Gerecht, “the advantage [of using somatic stem cells] is that they will readily become functional cells. The disadvantage is that the number of somatic stem cells is very limited in the body, and also in vitro, in the lab, we cannot expand them.” While embryonic stem cells will not necessarily differentiate into a desired cell type, somatic stem cells are already classified as one certain type, though they are smaller in number.3 Gerecht’s lab studies microenvironments of both cell types, focusing on the extra-cellular matrix (ECM) scaffold properties and their effect on vascular differentiation and regeneration. A clear understanding of the ECM’s properties will make possible the creation of a scaffold with specific qualities that will support blood vessel formation. Dr. Gerecht explains, “there are many technical issues in designing microenvironments. We need to control oxygen levels, make sure that the scaffold is biocompatible, and [consider] if it’s soft, stiff, or presenting different structures to the cells.” An important consideration of such work is the ECM’s elasticity, as the level of elasticity directs stem cell lineage specification; while stiffer matrices are myogenic, leading to the production of muscle cells, soft matrices generally produce neural cells.4 A certain level of cell-matrix elasticity has to be achieved for the stem cells to differentiate specifically into blood vessels. The composition and biophysical nature of the ECM are also large factors in its interaction with the stem cells. Various levels of proteins such as collagen, fibronectin, and lamanin will change how cells differentiate. The topography of the matrix (smoothness, roughness, and the corresponding
nanostructures) affects cell development as well, and should also be considered in the engineering of microenvironments. Other research groups are working on similar studies of stem cell microenvironments. At the Hôpital Maison Blanche in Reims, France, researchers Christelle Coraux, Jacqueline Roux, Thomas Jolly, and Philippe Birembaut identified interactions between the ECM and epithelial cells (the lining of the airways of the respiratory system) that influence epithelial differentiation. Differentiation of these cells is necessary for regeneration of the airway epithelium in patients who suffer from inflammatory respiratory diseases such as cystic fibrosis, chronic bronchitis, or asthma. The remodeling of the ECM by certain enzymes called matrix metalloproteinases is a large factor in the regeneration of epithelial cells through differentiation. Engineering of this type of microenvironment can lead to more effective treatments of respiratory diseases.5 Many types of stem cells are influenced by the extracellular matrix composition. In another recent study, Aditya Chaubey and Karen J.L. Burg in Clemson University’s Department of Bioengineering showed that ECM composition regulates the differentiation of somatic stem cells.6 Their research is focused on the differentiation of adult mouse bone marrow stem cells and fat cells, or adipocytes, with the goal of creating soft tissue implants. The microenvironment’s properties are especially important because specific conditions direct bone marrow stem cells, which are easier to acquire than adipose tissue, to differentiate into adipocytes. The findings of this study show that the presence of the protein laminin in the ECM supports adipogenesis. If other elements of the ECM composition can be identified, bone marrow stem cells from an individual’s body can be used to generate soft tissue implants that will replace transplants of adipose tissue and synthetic material with a more biocompatible alternative developed from an individual’s own cells. Though these breakthroughs in understanding the influence of stem cells’ microenvironment compositions are quite promising, there still remain many obstacles for researchers to overcome before these findings can be incorporated into clinical practice. Professor Gerecht identifies one main issue, that “there is a big leap between dif21
ferentiated cells and cells that are truly functional once in the body.” Cells are often developed in culture (in the lab environment), but when put into the body, do not regenerate as expected. In terms of her research, the cells have to actually behave like blood vessels after implantation, which is more difficult to achieve in humans than one would assume. So far, implantation of functional blood vessels in mice has been achieved by a group of researchers from various universities, who published their findings in 2007. Their research indicated that human embryonic stem cells were able to differentiate into endothelial cells, or blood vessels, and then successfully function in the host systems as blood vessels.7 This procedure would be significantly more complex with humans, and additional research and regulation is required before testing occurs. Another concern with the use of stem cells is that implanted cells that are not fully differentiated could lead to tumors and cause cancer. In October 2008, University of Michigan researcher Yukiko Yamashita and her team found evidence of an alarm in adult stem cells that warns against over-proliferation of cells in fruit flies, but no such alarm has been shown to exist in human stem cells thus far.8 Over-proliferation of cells would cause cancer because of the high number of cell divisions, while too few divisions cause aging; researchers are currently looking for the molecules that keep track of the balance and help prevent either scenario. Once the properties of this mechanism have been identified, stem cell implantation will be significantly less dangerous. Also recently in 2008, a research team at the University of Oklahoma headed by Courtney Houchen and Shrikant Anant successfully isolated cancercausing stem cells by identifying a specific protein contained in these cells.9 The team is now develop-
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ing a compound that should kill the stem cells and as a result, stop the progression of cancer in patients’ bodies. If this compound works properly, it should be available for use in treatment in about ten years, and could help create possibilities for other types of stem cell implantation. Researchers could use the compound to ensure that in case any cells remain undifferentiated or only partially differentiated, they will be stopped from causing cancer. Engineered microenvironments could be more readily tested and used once researchers overcome this obstacle. Should scientists find ways around these remaining complications, the implications of these findings and the possibility of engineering microenvironments are astounding. Dr. Gerecht puts it clearly: the future of this research is such that “we will have blood vessels by order,” or essentially any type of tissue at our disposal without having to worry about transplants and donor compatibility. In effect, the study and engineering of microenvironments brings us one step closer to the exciting prospect of being able to regenerate our own organs. References 1. 2. 3. 4. . . .
8.
The National Institute of Health. Info Center: Stem Cell Basics. Retrieved October 7, 2008 from http://stemcells.nih.gov/info/basics/basics2.asp Siminovitch L, McCulloch EA, Till JE (1963). The distribution of colony-forming cells among spleen colonies. Journal of Cellular and Comparative Physiology, Vol 62: 327–36. Personal Interview with Dr. Sharon Gerecht (October 2008). Engler A.J., Sen S, Sweeney H.L, Discher D.E. (August 2006). Matrix elasticity directs stem cell lineage specification. Cell, Vol 126, No. 4: 645-7. Coraux C, Roux J, Jolly T, Birembaut P. (August 2008). Epithelial cell-extracellular matrix interactions and stem cells in airway epithelial regeneration. The Proceedings of the American Thoracic Society, Vol. 5, No.6: 689-94. Chaubey, Aditya & Burg, Karen J.L. (2008). Extracellular matrix components as modulators of adult stem cell differentiation in an adipose system. Journal of Bioactive and Compatible Polymers, Vol. 23, No. 1: 20-37. Wang, Z., Au, P., Chen, T., Shao Y., Daheron, L.M., Bai, H., Arzigian, M., Fukumura, D., Jain, R.K. & Scadden, D.T. (2007). Endothelial cells derived from human embryonic stem cells form durable blood vessels in vivo. Nature Biotechnology, Vol. 25: 317-18. (2008, September 11) EurekAlert. Scientists isolate cancer stem cells. Retrieved October 6, 2008 from http://www.eurekalert.org/pub_releases/2008-09/uoosic091108.php
Is HDL Really the “Good Cholesterol”?
Nezar Alsaeedi / HURJ Staff Writer Amidst the torrents of human disease and sickness, medical science has become the “poster child” for mankind’s greatest achievement. It is an unequivocal fact that in the past century, medicine has approached the podium of progress as a victorious human feat, influenced by improvements in biotechnology and a more comprehensive understanding of microorganisms and their functions. Building on this success, this ancient science has developed some rules to govern the human body against infection and disease. How many times have patients with heart disease risks been advised to increase the levels of their high-density lipoprotein (HDL) and lower their low-density lipoprotein (LDL)? These rules have been ingrained in every medical student’s mind. Surely, anyone taking a biochemistry test would have written “LDL” for the “bad cholesterol” question and gotten it right! However, with the advancements in scientific understanding, 23
ideas that we considered to be facts turned into disprovable fiction, only to be discarded in the waste bin of human intellect. Like so many of the facts before it, the notion of HDL as “good cholesterol” approaches this same fate. According to Subroto Chatterjee, PhD, a professor at Johns Hopkins School of Medicine who studies atherosclerotic plaques, not every kind of HDL is good for you. In fact, his collaborative group of atherosclerosis experts has proven that some HDL molecules actually cause drastic effects that can bring about sudden heart attacks and strokes. For the past eighty years, cardiovascular diseases (CVD) have been the leading cause of death in the United States. According to the Center for Disease Control statistics, various heart diseases accounted for 652,091 deaths in the year 2005 alone. In addition, the economic costs of heart disease are immense, exceeding one hundred billion dollars in 2007 for both direct health costs (physician and medicine expenditures) as well as indirect costs (loss of productivity due to mortality). In light of these statistics, the future that lies ahead seems daunting, especially when the first symptoms of heart disease are strokes and heart attacks. Faced with these overwhelming numbers, physicians were quick to respond with a simple diagnosis that linked the risk of heart disease to elevated levels of low-density lipoproteins (LDL), globular molecules that consist of proteins and lipids transporting cholesterol to the arteries of peripheral tissues in the body. Immediately, a medical dogma
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was established that accused LDL of being the culprit for increased susceptibility to heart disease, that could very likely lead to heart attack, stroke, and subsequent death. Moreover, physicians later discovered that high-density lipoproteins (HDL) could combat the effects of LDL by transporting cholesterols away from the arteries in the body and towards the liver. What ensued was a standard law in CVD research that simply labeled LDL as “bad cholesterol,” while extolling HDL as the “good cholesterol.” Only in recent years has this standard law been broken, ushering in a revolutionary way of thinking about the complexity of heart disease, especially disease caused by atherosclerosis. Some HDL molecules were found to increase the susceptibility to heart attacks and strokes because they induce smooth muscle cell death through a complex signaling pathway. This discovery not only deepens our understanding of cardiovascular diseases, but it also illustrates the dangers of oversimplifying a complex biological mechanism that could unintentionally lead to deleterious effects. A significant contributor of heart disease is atherosclerosis, classified by a hardening of the arteries due to the accumulation of cholesterol in the form of a plaque-like material. These plaques are formed when oxidized LDLs embed themselves in the walls of arteries, signaling an inflammation response. As a result, macrophages (cells that engulf and digest foreign material in the body) arrive at the arterial walls and try to digest the oxidized LDL molecules. The macrophages fail in this task and instead deposit themselves with the engulfed cholesterol inside the arterial lesions. As this plaque of cholesterol and macrophages accumulates, a fibrous cap consisting of smooth muscle cells covers it causing a restriction in the arterial diameter, thereby restricting the flow of blood to the organs. Although this restriction of blood flow, also known as ischemia, causes increased blood pressure, it can be regulated by dietary restrictions and the right amount of
exercise. The arterial vessels can also stretch to accommodate for the bulging plaque to increase blood flow. The main danger occurs when the fibrous covering of the plaque ruptures, causing a clot to form inside the blood filled lumen of the artery. This clot can instantly cause a stroke or heart attack, and was the main concern of Dr. Subroto Chatterjee’s when examining the effects of a special type of HDL that induces smooth muscle cell death. Dr. Chatterjee’s team discovered that HDLs containing apoliprotein C-I (apoC-I) actually induced aortic smooth muscle cell death in vitro. Apoliproteins are embedded within the lipid layer and form the protein framework of the lipoproteins that transport cholesterol throughout the body. The team first incubated aortic smooth muscle cells containing no apoliprotein, purified apoliprotein C-I, and purified apoliprotein C-III. The cells were treated with a white 4’, 6’-diamidino-2phenylindole dihydrochloride (DAPI) stain that binds to the nuclei of cells. An apoptotic (dying) cell shows a somewhat fragmented nucleus with fluorescent microscopic analysis of DAPI. This was the precise observation noticed by the team, to a considerable degree, in cells incubated with apoC-I. Normal cells showed 2.24% apoptosis, apoC-III cells showed 4.78% apoptosis, and 26.19% of apoCI cells were apoptotic. To further substantiate this data, the Johns Hopkins team cultured smooth muscle cells with HDL and apoC-I and smooth muscles cells with apoC-I poor HDL. Again, a corollary relationship was shown as about 50% of the apoC-I +HDL smooth muscle cells were apoptotic while a mere 2% of apoC-I poor cells were apoptotic. The second part of the experiment attempted to understand the mechanism through which apoC-I acted to induce smooth muscle cell death. To accomplish this, the Johns Hopkins team first hypothesized the presence of a signaling pathway that triggers apoptosis in cells after contact with apoC-I. In accord with this hypothesis, the team introduced several inhibitors that were known to stop certain stages of the cell-signaling pathway. They found that the GW4869 inhibitor that interfered with the neutral sphingomyelinase
(N-SMase) enzyme substantially reduced apoptosis in smooth muscle cells. This result was crucial since it provided an enzyme that was implicated in the apoptosis process, and could be targeted in future drug therapy projects. The team then analyzed the role of the neutral sphingomyelinase in the apoptosis pathway. They measured the activity of N-SMase in cells incubated with HDL and apoC-I. These cells showed a 2.6 fold increase from baseline in N-SMase activity at 5 minutes, followed by 2.7 fold increase at 10 minutes. This pattern was not seen in either control cells with no HDL or in cells with apoC-III. What these results suggested was that apoC-I did in fact lead to an increase in activity of the neutral sphingomyelinase enzyme that was a proponent of the cell apoptosis pathway. Moreover, C-2 cermide−an important signaling compound involved in apoptosis−was introduced into the cells incubated with HDL + apoC-I and the GW4869 inhibitor. The results illustrated that ceramide actually restored apoptosis to somewhat normal levels without the NSMase inhibitor. This suggested that ceramide could be used to bypass an inhibited NSMase enzyme and continue the apoptosis pathway. It also indicated that the N-SMase enzyme was located upstream relative to the other signaling molecules of apoptosis, and a defective N-SMase enzyme would not produce ceramide that would eventually trigger other processes in the apoptosis pathway. Through these simple experimental procedures, Dr. Chatterjee’s team of atherosclerosis scientists identified a possible enzyme responsible for apoC-I induced apoptosis, and clearly demonstrated that it could be inhibited to prevent smooth muscle cell death. This series of experiments carries wide and varied implications in the application of medicine as well as conventional medical knowledge. The conclusion that the apoC-I apoliprotein on HDL could actually lead to smooth muscle cell death truly appreciates the complexities associated with heart disease. In previous experiments, scientists have shown that cells taken from the cord blood of babies with low birth weight (a sign associated 25
with increased heart disease) contained a high percentage of HDL with apoliprotein C-I. Although this study provided a first glimpse at the dangers of some HDL molecules, it was not pursued further until this recent investigation by the Johns Hopkins team. These experiments add another dimension to our understanding of heart disease. They signify that not only is cholesterol implicated in CVD, but proteins that change the interactions of lipoproteins with the arterial cells also play a significant role. Hence, in future drug therapy projects, a two-pronged approach must be pursued to treat both issues of cholesterol and apoliproteins. The main concern coming out of this study is how these results help doctors and cardiologists make the right choices when treating patients with cardiovascular problems. One argument is that doctors will be more careful in prescribing treatments that increase the levels of HDLs. Today, the current dietary treatment for patients suffering from high blood pressure is to consume more niacin (vitamin B3) that is found in many foods including beef, chicken, fish, and eggs. Niacin is thought to decrease the levels of LDLs while increasing the levels of HDLs in the blood stream. But imagine a scenario in which a 60-year old patient suffering from high blood pressure is prescribed this niacin treatment. With plaques already accumulated in his arteries, this niacin treatment might unintentionally lead to his death. If the HDL containing apoliprotein C-I is increased, it would cause his vulnerable arterial plaques to rupture resulting in myocardial infarctions and strokes. Therefore, niacin would not be the best approach in this case. Based on the Johns Hopkins study, a plausible approach to this issue would be to target the neutral sphingomyelinase pathway that leads to apoptosis after contact with apoliprotein CI. The study has proved that certain inhibitors, like GW4869, can inhibit the activity of NSMase, thereby decreasing the level of apoptosis of smooth muscle cells. In light of this current data, it would seem reasonable to suggest a treatment consisting of an N-SMase enzyme inhibitor in conjunction with a drug that lowered LDL levels in people suffering from high blood pressure. Equipped with this knowledge, health professionals can make these medical judgments 26
to suit the CVD patients’ best interests. Medical science is a continually evolving discipline that depends on innovative and groundbreaking works to maintain its progress. It has developed factual rules that govern the workings of the human body and its interactions with diseases; however, these rules are provisional and must be reformulated with the advent of new conclusions emanating from scientific experimentation. This was the case with the work of Dr. Chatterjee and his team as they tackled one of medicine’s popular dogmas, that HDL was the “good cholesterol”. The team’s work expressed the need for revolutionary thinking to challenge accepted standards and norms. Only through this critical mindset and a deeper appreciation for the complexities of diseases can health care professionals push the frontiers of modern medicine to accommodate for the progress yet to come. Nezar Alsaeedi is junior majoring in Molecular and Cellular Biology at the Johns Hopkins University. References: 1. 2. 3.
4.
Americanheart.org. 10 Nov. 2008. Cholesterol and Atherosclerosis in Children. Sept. 1993 http://www.americanheart.org/presenter. jhtml?identifier=4499. CDC.gov 16 Feb. 2007. Prevalence of Heart Disease-United States,2005. 11 Nov. 2008 http://www.cdc.gov/mmwr/preview/mmwrhtml/mm5606a2. htm. Kolmakova A, Kwiterovich P, Virgil D, Alaupovic P, Knight-Gibson C, Martin SF, Chatterjee S. Apoliprotein C-I Induces Apoptosis in Human Aortic Smooth Muscle Cells via Recruiting Neutral Sphingomyelinase. Arteriosclerosis Thrombosis Vascular Biol. 2004; 24:264. Mayoclinic.com. 28 June 2008. Arteriosclerosis/atherosclerosis. 20 Nov. 2008 http://www.mayoclinic.com/health/arteriosclerosis-atherosclerosis/ DS00525.
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