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About The McMaster Meducator The McMaster Meducator is an undergraduate medical journal that publishes articles on current topics in health research and medical ethics. W e aim to provide an opportunity for undergraduate students to publish their work and share information with their peers. Our protocol strives to maintain the highest standard of academic integrity by having each article edited by a postgraduate in the relevant field. W e invite you to offer us your feedback by visting our website: (www.meducator.org).

Virotherapy

Siddhi Mathur

Comparative Genomic Hybridization

Mark Adams

The McMaster Meducator may be contacted via our e-mail address: meduemail (filearnlink.mcmaster.ca or our mailing address: B.H.Sc. (Honours) Program Attention:The McMaster Meducator Michael G. DeGroote Centre for Learning and Discovery Room 3308 Faculty of Health Sciences 1200 Main Street West Hamilton, Ontario L8N 3Z5 http://www.meducator.org

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Prostate Cancer

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Issue 101 March 2007

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Dear Reader, Meducator Staff his year is already shaping up to be another exciting one in medicine. Vaccine programs for H P V have started in various states, the incoming C M A president is a staunch supporter of starting a privatized healthcare sector, and Canadian researchers recently discovered n e w genetic markers c o m m o n to all Alzheimer's patients which will hopefully result in rapid and accurate future diagnoses. This terse survey of what has already transpired demonstrates that the field of medicine continues to quickly evolve. I hope you, our readers, will find that our MedWire is a useful tool to catch up on recent breakthroughs that you might have missed.

Most of today's medical research relates to solving a problem in an innovative way, which is the overarching theme of this issue. Mark A d a m s takes us through current high-resolution tools for identifying genetic irregularities while Siddhi Mathur writes about virotherapy - a novel w a y of introducing therapeutic genes through attenuated viruses. As the popularity of laparoscopic surgery continues to increase, Russell Fernandes presents an excellent overview and technological assessment of roboticassisted laparoscopic removal of cancerous prostate glands. For something a bit closer to h o m e , A m a n d e e p Rai provides a comprehensive review of evidence-based medicine - one of McMaster's greatest contributions to medicine. Finally, as a n e w tradition of including a column written by a professor in each issue, Dr. Randall addresses several misconceptions held by m a n y Canadians of a "private" healthcare system.

President Jonathan Liu

Yours Truly,

Creative Director Crystal Chung V P Medical Research and Health Ethics Jeannette So Shama Sud Sarah Mullen Harjot Atwal Harman Chaudhry VP Public Relations Amandeep Rai V P W e b Design Fify Soeyonggo V P Communications Alexandra Perri

Dr. Gordon Guyatt B.Sc, M.Sc, M.D., F.R.CP.C Dr. Edward D. Matsumoto M.D., M.Ed., F.R.C.S.C.

Jonathan Liu B.A.Sc III www.meducator.org

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Vice-President Tyler Law

VP Adminstration I would first like to thank each writer and post-graduate editor for their time and contribution; Navpreet Rana this publication exists because of your collaborative efforts. It has also been a pleasure working with a team of talented editors, designers, and marketers. There are m a n y I would like to thank Junior Executives Jacqueline H o once more: Tyler Law, for your invaluable advice; Crystal Chung, for the extra time you put Stephanie Low into re-designing the layout; S h a m a Sud, Jeannette So, Harman Chaudhry, Harjot Atwal, and Siddhi Mathur Sarah Mullen, for your attention to details; A m a n d e e p Rai, for your ceaseless marketing wit; Ran Ran Navpreet Rana, for keeping us organized; Ran Ran, for the unprecedented cover designs; Stephanie Low, Jacqueline Ho, and Siddhi Mathur, the future of this publication; and Dr. Del Harnish along with the Bachelor of Health Science staff, w h o have all supported us in every possible way. Post Graduate Editors For those wishing to join the team next year, I encourage you to visit our webpage (www. meducator.org) in early September for applications. W e also welcome submissions pertaining Viola Freeman B.Sc, to topics in medicine and medical ethics from undergraduate students from any field of study. Finally, on behalf of the entire Meducator staff, w e hope you find this issue both enjoyable A.R.T. (Cytogenetics) and informative!

Dr. Karen Mossman H.B.Sc, Ph.D

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Issue 101 March 2007

"MEDUUIOIl 4 Qt A n e w study by Harvard ^ researchers in Botswana found 1 ^ that w o m e n can take the anti^ ^ AIDS drug, Nevirapine, to protect â&#x20AC;˘ ^ 5 their unborn children without â&#x20AC;&#x201D; . endangering their ability to ^ ^ undergo life-saving antiretroviral ^ ^ treatment later on.

Researchers from the Institute for Regenerative Medicine in North Carolina recently reported that freely floating cells in the amniotic fluid of pregnant w o m e n have the same traits as embryonic stem cells, including an ability to grow into brain, muscle and other tissues that could be used to treat a variety of diseases.

"Evidence-based medicine", a phrase and process devised by a team of researchers from McMaster University in 1991, has been listed as one of the 15 greatest medical breakthroughs since 1840 by British Medical Journal.

Researchers at the Massachusetts Institute of Technology have found that taste preferences changed w h e n informed of a secret ingredient prior to consumption. Subjects were given two beers to taste, a regular draft and another with a few added drops of vinegar. W h e n unaware of the vinegar,

6 0 % of the participants preferred the altered beer. Even upon discovering the addition of vinegar, their preference remained. However, w h e n told there was vinegar before consumption, only a third of the participants preferred the modified drink. The study showed that taste experiences were influenced by their expectations.

containing pharmaceutical compounds. This procedure will hopefully allow the production of eggs with extra nutritional value.

changes m o o d , sexual arousal, physiological arousal and brain activation in females.

The F D A has approved the first over-the-counter drug for weight loss which is a less potent dose of the prescription drug, Xenical. It supposedly allows an extra two to three pounds of weight loss for every five pounds lost by means of diet or exercise. Critics argue that this 'quick fix' is unlikely to solve America's obesity problem.

ResearchersfromGermany, Britain and Japan were able to predict decisions of the h u m a n mind through the use of functional magnetic imaging. Patterns of the brain were analyzed by Pre-menopausal w o m e n computer programs to w h o eat 30g of fibre a day reveal specific thoughts and have half the risk of breast intentions. These brain scans cancer compared to those will hopefully be of use to w h o eat only 20g. Researchers help paralyzed individuals from the University of Leeds communicate. A n estimated 40 million believe that fibre affects body people in the U.S. receive care processes and regulation of from physicians w h o do not estrogen. To consume 30g of Yale University researchers feel that they have to disclose fibre, a person would have to recently discovered that lack treatment options that they eat high-fibre cereal, brown or of sleep m a y prevent the themselves find objectionable. wholemeal bread and have at growth of n e w brain cells. In This suggests that patients least five portions of fruit and a study comparing rats that wanting information or access vegetables a day. were deprived of sleep for 72 to controversial medical

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A team led by Dr. Sabina Lim in South Korea has tested acupuncture therapy on mice with symptoms of Parkinson's disease, such as loss of dopamine. Almost 8 0 % of dopamine was retained in mice treated by acupuncture whereas the control group lost about half of their original dopamine levels. Conclusive experiments in h u m a n models have yet to begin.

British scientists have injected sequences of D N A into an egg to modify the chicken chromosomes. This allows the new, genetically modified chickens to lay eggs

hours versus rats that were not, there were significantly fewer n e w brain cells in the hippocampus region and elevated corticosterone levels in the sleep-deprived rats.

treatments and procedures need to proactively question their physicians in order to receive full disclosure.

UK researchers have successfully demonstrated in mice models the phenotypic University of California, reversal of the mutant M E C P 2 Berkeley researchers have gene, which is the cause of Rett discovered that the scent of Syndrome (RTT) - a syndrome male sweat raises Cortisol similar to autism. The mice levels in females. Cortisol is regained normal breathing, important for maintaining mobility, gait, and various arousal and a sense of well- electrophysiological functions being, in addition to other of the brain. Researchers stress-related functions. The anticipate that these findings study compliments earlier m a y facilitate the development findings that andrastiedone, of therapies that will reverse which is found in male sweat. the neurological d a m a g e in

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Issue 101 March 2007 children and adults with RTT, as 50 percent. Researchers believe well as autism and other related that the foreskin is susceptible neuropsychiatric disorders. to tears and ulcers which act as entry points for this virus. Circumcision is projected to save over 3 million lives in the next 20 years, however, there are many cultural barriers to implementing this procedure.

Researchers at McGill University have found that n e w drugs for the treatment of diabetes and obesity also combat certain types of breast cancers. The drugs counteract the key gene present in 40 percent of breast cancers by suppressing the PTP-1B enzyme, which is overactive in all three ailments.

A n ongoing, six-year Greek study found a correlation between taking midday naps and reduced risk of coronary disease. The researchers looked at over 20,000 m e n and w o m e n between the ages of 20 and 86 and found a 30-minute nap led to a 6 4 % reduced risk of heart attack a m o n g workers and a 3 6 % reduced risk a m o n g nonworkers.

A recent study by London's Portland Hospital has confirmed that changing hormone levels during a woman's menstrual cycle makes them more prone to injury. Near the middle and end of their cycle, women's estrogen levels, a hormone which is responsible for muscle and ligament tissue strength, drop dramatically and often lead to back pain. This information will help w o m e n , The Governor of Texas, particularly female athletes, plan their schedule according to w h e n Republican Rick Perry, has signed an order making Texas the first they are most vulnerable to pain and aid them in avoiding injury. state in which it is mandatory that girls at the age of 11 years receive Gardasil; the vaccine against the Since the birth of Dolly, there HPV virus which is responsible for has been explosive interest in causing cervical cancer. Various the process of cloning animals conservatives and parents' rights through the S a m e Nuclear groups argue that this vaccination Transfer Technique. Despite condones premarital sex and scientists continuing efforts, contradicts the way in which they the efficiency of cloning is still parent their children. depressingly low. Scientists have demonstrated that the use of keratinocytes as opposed Preliminary results in a study to cumulus cells increases the of Ugandan m e n show that male circumcision is effective in the efficiency of the S a m e Nuclear Transfer Technique by more than prevention of HIV. M e n w h o are fourfold in male mice (5.4% vs circumcised decreasetheirchances 1.2%). of acquiring the infection by over

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Glen E.Randall P h D Assistant Professor, Health Services Management, DeGroote School of Business, McMaster University Member, Center for Health Economics and Policy Analysis, McMaster University

PRIVATE HEALTHCARE: PANACEA OR PRELUDE TO DISASTER It has been my experience in recent years that the mere mention of "private" healthcare can send Canadians into a tizzy. For m a n y Canadians, our "public" healthcare system is a symbol of our underlying values of equality and fairness and any major infusion of private care would be courting disaster by creating a "two-tier" system (one for the rich and one for the poor). For other Canadians, our healthcare system is broken and in desperate need of repair. These individuals see the private marketplace as an obvious solution to our healthcare woes. They believe that the competition associated with enhancing private care will lead to shorter wait times, greater consumer choice, and generally a more efficient system. M a n y Canadians are passionate about the issue of "public" versus "private" since it confronts their core values. But issues in life are rarely black and white and the entrenchment of views is often exacerbated by c o m m o n l y held misconceptions. This appears to be the case in the current healthcare debate. O n e misconception is that more private care will automatically result in a better system. While market mechanisms can be powerful in achieving efficiency, the reality is that, for numerous reasons, the characteristics of healthcare markets leave them far from the market ideal. For example, it is exceedingly difficult for most individuals to assess the quality of services or to "exit the market" w h e n they are not happy with services provided. Despite this, the lure of the marketplace has been so strong that countries continue to look for market-based solutions for their healthcare problems in the face of growing evidence that m a n y of these initiatives have produced underwhelming results. Another misconception is that the Canadian healthcare system is "public" while the American system is "private". In actuality, both are mixed systems which e m brace elements of public and private financing and service delivery. Recent estimates of the public/private mix for financing of health services are approximately 70/30 in Canada and 40/60 in the United States. Canada has a long history of "private" healthcare. M a n y Canadians have private insurance to cover the cost of drugs and dental care; healthcare providers frequently operate private "for-profit" practices; and most of our hospitals are actually private (albeit not-for-profit) organizations which operate with "public"funding. M u c h of the debate about "privatization" is really about the provision of "for-profit" care. Since healthcare primarily falls within provincial jurisdiction, w e have s o m e variation a m o n g the rules for providing for-profit healthcare across the country. Private healthcare is neither a panacea nor is it something to be feared and Canadians would benefit from a shift from discussing public versus private to focusing on a more nuanced discussion of the relative mix of public and private within our healthcare^ystem.

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The Ashley Treatment: Forever Young'

MedBulletin by Jacqueline Ho

In early January 2007, Ashley X was introduced to the world. Born with static encephalopathy, severe and irreversible d a m a g e of the brain, Ashley has the mental ability of a three-month-old baby, despite being nine-years old. Unable to walk or talk, Ashley will remain a mental infant for the rest of her life. Her parents, w h o remain anonymous, have opted for treatment that will 'freeze'their daughter from aging. Her doctors are authorized to remove her uterus, her breast buds and inject hormones to restrict her growth. Ashley's parents emphasize that their actions are in the best interest of their daughter, and that the "central purpose treatment is to improve Ashley's quality of life". With the treatment, Ashley will be free of menstrual cramps, and the weight of large and fully developed breasts. Her smaller size will allow her parents to provide more effective care. George Dvorsky, of the Board of Directors for the Institute for Ethics and Emerging Technologies stated, "the estrogen treatment is not what is grotesque here. Rather, it is the prospect of having a full-grown and fertile w o m a n e n d o w e d with the mind of a baby." Agnes Fletcher of the Disability Rights Commission views this as "unnecessary medical treatment" that is a technical solution to a social problem. O n e of the reasons for the treatment is that Ashley's parent's cannot afford paid caregivers to support their daughter at home. Fletcher states, "[with] such trying circumstances, it is small wonder that they consider desperate measures". Fletcher states that though Ashley's treatment is controversial, the "real scandal" is the failure of developed countries like Britain and the US to provide sufficient support services to ensure all their citizens have Age: 27 access to a decent quality of life.

Mental Ability = 3-month-old baby

The Pill... for m e n

BBC. (2007) Treatment keeps girl child-sized. Retrieved January 7th, 2007, from http://news.bbc. co.uk/2/hi/americas/6229799.stm (2007)The"Ashley Treatment". Retrieved January 14th, 2007, from http://ashleytreatment.spaces.live. com/?_c11_blogpart_blogpart=blogview&_c=blogpart&partqs=amonth%3dl%26ayear%3d2007 BBC. (2007) 'Frozen girl'debate. Retrieved January 14th, 2007, from http://news.bbc.co.Uk/2/hi/ health/6230045.stm#brosco

MedBulletin by Siddhi Mathur

Researchers at the University of Pennsylvania have treated five HIV patients with a disabled version of HIV.Though there are a multitude of mechanisms in place to control the fertility of w o m e n ; men, however, have a narrow range of choices. Currently, the main options for male fertility control include abstinence, condoms, or a vasectomy.

Ever since the female pill was first commercialized in the 1960s, researchers have been racing to find a pill for men. Ma experiments and trials tried to develop a male pill using testosterone to trick the brain into turning off sperm production. This is similar to the use of progesterone in w o m e n to turn off ovulation. However, the use of testosterone did not prove very effective for stopping sperm production. Nonetheless, recent research suggests that there is another hormone responsible for the production of sperm: prolactin, a hormone also present in w o m e n which is involved in the production of breast milk. Nevertheless, to use as a contraceptive, tablets that inhibit the production of prolactin must be taken once every day in addition to injections or patches of testosterone. Researchers still face challenges, such as the potential side effects of using testosterone. Before the drug can be commercialized, trials assessing efficacy of the drug must be conducted. However, a shortage of male volunteers for trials and studies plagues efforts for further data collection. Currently, researchers in Australia are testing a recently developed molecule called Adjudin on rats. This molecule works to dislodge the sperm from Sertoli cells, causing the sperm to be ineffective. The goal of this research was to create a nonhormonal molecule that affects a particular step in spermatogenesis. These are promising findings but there is still a daunting amount of research to c o m e before this molecule can be tested on humans. (October 30, 2006).'Sperm-stopping' male pill hope . Retrieved November 24, 2006, from BBC News W e b site: http://news.bbc.co.Uk/2/hi/health/6091582.stm Macnair, T (November 2006). The male contraceptive pill. Retrieved November 24, 2006, from http://www.bbc.co.Uk/health/mens_health/body_sexpill.shtml#injections_and_patches

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Issue 101 March 2007

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N O W yOU See the tUmOUr, n O W yOU don't

MedBulletin by Jacqueline Ho

In healthy cells, the tumour-suppressing gene p53 regulates the cell cycle, activating DNA reparations and preventing faulty D N A from being replicated. Irreparably damaged D N A causes the cell to undergo programmed cell death (apoptosis) induced by p53. In the absence of p53, this fail-safe mechanism is lost and the likelihood of cancer increases. Studies carried out by two groups of researchers in New York's Cold Spring Harbor Laboratory and the Massachusetts Institute of Technology (MIT) appeared to have found a way to shrink cancerous tumours by reactivating p53. The p53 gene is inactivated or mutated in the majority of h u m a n cancers; w h e n reactivated, the p53 gene was able to stimulate a variety of tumours to shrink. In animal experiments, w h e n p53 was only briefly reactivated, a dramatic reduction in tumour size occurred. There were even cases where the tumour was completely eradicated. The MIT team discovered that responses to p53 activity vary according to the tumour type. While lymphoma cells selfdestruct, sarcoma cells age and b e c o m e unable to divide. The N e w York team, w h o worked with a liver tumour, found the aging was caused by an i m m u n e response. This causes increased activity of molecules that serve to eliminate cancer cells. Furthermore, the reactivation of p53 caused no d a m a g e to normal cells where the gene was not previously expressed. The studies, published in Nature, provided critical genetic evidence that showed constant repression of the p53 gene is essential for tumour survival. These findings also raise hopes of creating a n e w class of anti-cancer drugs to treat h u m a n cancers in the future.

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BBC (2007) Gene switch makes tumours shrink. Retrieved January 24th, 2007, from http://news.bbc. co.uk/2/hi/health/6291855.stm

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Informed consent not very informative

MedBulletin by siddhi Mathur

Cancer stricken patients agree to radiation therapy believing that they are receiving the best possible care. Instead, th may be given experimental treatments without compete consent. This occurred in the 1960s in MIT, where physicians used experimental drugs and treatments on cancer patients. They claim, however, that the patients were seeking the treatment because they were left with no hope and no other options.

The question that remains: Are patients today becoming part of drug trials without complete and accurate informed consent Experts say it is highly unlikely that patients are not asked to sign consent forms that do not include a complete explanation on the type of treatment they are about to receive. However, some of the circumstances that led to the cases at MIT are relevant today.

Just like the'60s, terminally ill patients hold on to every possible thread of hope, even if it means being part of an ex treatment trial. The reality, however, is that research participation should be a last resort for patients. Also, for extremely ill patients the odds of benefiting from experimental treatments are miniscule. It is the hope and desperation of these patients that makes them vulnerable to exploitation. Patients can be overwhelmed by the complexity and amount of information given to them by their doctor. At this point, it is easy to undermine the risks of the treatment and exaggerate its benefits, especially w h e n the patients and their families have high hopes for a recovery.

From a researcher's point of view, how will advances be made if patients do not volunteer to become part of trials? It is from a trial, a test, that a concrete treatment is born. Moreover, physicians do their best to inform patients on what it means to be in a research-based path of treatment. Even if the treatment may not hold m u c h benefit for the patient, the data is valuable to researchers, and consequently, to future patients. Where is the balance? Patients will trust their doctor's advice when participation in a research study is recommended. Nevertheless, it is the doctor's ethical duty to ensure that the patient is completely aware of the risks and realistic benefits of the treatment. It is true that research creates medical advances; but it must not c o m e at the cost of failing to respect participants. Kahn J. CNN. (2000). Blinded by hope, Dazzled by detail. Retrieved on February 7, 2007 from http:// www.cnn.com/HEALTH/bioethics/9903/research.dangers/template.html.

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Issue 101 March 2007

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Editorial: Evidence-Based Medicine

EVIDENCE-BASED MEDICINE (EBM), RECENTLY HERALDED AS ONE OF THE TOP 15 MEDICAL BREAKTHROUGHS, INVOLVES THE USE OF THE BEST AVAILABLE MEDICAL LITERATURE, IN ADDITION TO KNOWLEDGE OF DISEASE MECHANISMS, TO IDENTIFY THE BEST CLINICAL DECISION. THIS ARTICLE OUTLINES THE ARGUMENT FOR EBM, THE METHODOLOGY BEHIND ITS PRACTICE, AND SOME COMMON MISCONCEPTIONS REGARDING ITS USE.

Kayi Li Amandeep Rai

I n January 2007, the British Medical Journal published a comprehensive list of the top fifteen medical breakthroughs since the journal's inception in 1840. Breakthroughs ranged from antibiotics, birth control, and vaccines to the theory of evidence-based medicine (EBM) which was developed, in large part, at McMaster during the 1980's and emerged with publications from McMaster University in 1991 and 1992.

experts and presents a problem-solving strategy with a focus on utilizing the best available evidence. In addition to pathophysiological knowledge and clinical experience, a physician must possess the necessary skills to retrieve, critically appraise, and appropriately implement medical literature, in the context of the values, preferences and health status of the patient (Guyatt et al., 1992). At its core, "evidence-based medicine is an explicit and formal problem-solving strategy" (Montori & Guyatt, 2002).

WHAT IS EVIDENCE-BASED MEDICINE? How is EVIDENCE-BASED MEDICINE PRACTICED? According to Dr. David Sackett, a member of the original team, E B M is "the conscientious, explicit and judicious use of current best evidence in making decisions about the care of the individual patient. It means integrating individual clinical expertise with the best available external clinical evidence from systematic research." (Schartd, 2004). EBM represents a paradigm shift in the practice of clinical medicine.The old paradigm relies on a sound understanding of disease mechanisms and pathophysiology, and building a foundation of knowledge through unsystematic clinical observations. This foundation of content and expertise guides clinical decision making (Guyatt et al., 1992). The n e w paradigm displaces the emphasis from

N of 1 randomized trials Meta-analyses of randomized trials Randomized controlled trials Systematic reviews of observational Observational studies Physiologic studies Unsystematic clinical observations Figure 1: The increasing quality of evidence. Modified from Montori et al., 2002.

Formulate a Question The first step to practicing evidence-based medicine is formulating a question following the PICO approach. PICO comprises four important components of a good clinical query: the patient population, the intervention, the control, and the outcome of interest (Belsey & Snell, 2003).

Retrieving Evidence With a clinical question guiding the search, a prudent clinician must identify the highest quality of available evidence. Differentiating studies in terms of quality can follow a defined hierarchy of evidence (Figure 1) (Montori etal., 2002) This hierarchy differentiates evidence, but also demonstrates that evidence is always present in s o m e form. W e a k evidence is provided by a physician's personal experience or discussion with a colleague about prior cases. Physiological studies are of greater quality because they provide biological support (Montori et al., 2002). Observational studies examine the effects of an intervention on a population over time; their main drawback is that patient allocation into groups are based on physician or patient preference, as opposed to randomization (Guyatt & Rennie, 2002). Systematic reviews that combine the results of multiple studies addressing the same question

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Issue 101 March 2007

"MEBimjim

provide a stronger impetus for directing clinical action. A randomized control trial improves on an observational trial because individuals are randomly assigned to either the control or intervention arms of the trial. Naturally then, a meta-analysis of randomized control trials addressing the same question will provide a more accurate estimate of the true treatment effect. Finally, the N of 1 trial provides the best evidence for guiding clinical practice. N of 1 trials are studies designed by the clinician and the only subject is the patient in question. The trial will determine the best intervention for that patient (Guyatt et al., 2002).

Critical Appraisal After identifying a potential article, a clinician must critically appraise its applicability based on three questions:

â&#x20AC;˘ Are the results valid? â&#x20AC;˘ What are the results? â&#x20AC;˘ Are the results applicable to my patient? The validity of the results is established by evaluating the study's methodological quality, which entails features such as adequate blinding, allocation concealment, randomization, and completeness of follow-up (Guyatt et al., 2002). The results are assessed by examining the magnitude and precision of the treatment effect. Clinicians should be aware of the relative risk reduction, the numberneeded-to-treat, and the confidence intervals of therapeutic trials (Guyatt et al., 2002). W h e n determining the applicability of the results, the physician should try to determine if the subjects of the study are similar to the patient. If so, does the study evaluate patient-important outcomes? Finally, if the patient is somewhat different from the study subjects, does this difference shift the balance between benefits and risk? (Guyatt etal., 2002)?

COMMON MISCONCEPTIONS OF EVIDENCE-BASED MEDICINE Shortage of Literature Physicians practicing EBM must realize that they will encounter situations where there is minimal, or even a lack of relevant medical literature. While the continued expansion of research will address this shortcoming, clinicians must realize that there is always evidence. It m a y be less than ideal, and evidence that is lower on the hierarchy, but it does, nonetheless, exist. Evidence-based medicine suggests use of the best available evidence (Straus &McAlister, 2000).

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Figure 2: E B M calls for the use of medical literature, such as the academic journals found in the McMaster Health Science Library.

There is a lack of evidence suggesting that EBM works Admittedly, no randomized control trial shave demon st rated the effectiveness of evidence-based medicine, and any such trial would face issues of sample size, biases, and blinding. Further, the trial would be hard to justify on ethical grounds: is it appropriate to withhold evidence from physicians and patients in the control arm of such a trial (Straus & McAlister, 2000)? Nonetheless, research does suggest that patients provided with interventions of demonstrated efficacy have better outcomes than patients w h o d o not (Straus and McAlister, 2000).

Evidence-based medicine disregards clinical experience and knowledge EBM suggests the use of the best available medicine, not the disregard of important physician attributes. Experienced clinicians can ascertain a better diagnosis and m a y also possess superior technical skill, which can be important for diagnostic modalities such as ultrasounds. Furthermore, a thorough understanding of basic sciences is required so that the physician m a y quickly narrow d o w n the search. This

Issue 101 March 2007

"MEDIWJLllJli 10 knowledge of underlying mechanisms is also important in evaluating the applicability of literature to a specific patient (Straus & McAlister, 2000).

bedside to indicate whether harm or benefit will likely result. This allows patient values to be integrated into decision making about care and therapy provision (Straus & McAlister, 2000).

LOOKING INTO THE FUTURE

Knowledge translation will continue to be one of the biggest areas in the development of E B M application into clinical practice. Issues such as lack Difficulties transferring evidence of time or resources to retrieve the to actual patient care WHO HAS BEEN INVOLVED information, as well as critical appraisal skills, are challenges that need to IN THE DEVELOPMENT OF EBM? While variation in the biology of each be addressed by both academics patient likely hinders full application in the field and clinicians. With the Clinicians have always strived to of evidence, this is also a universal integrate the best available evidence development of online tools to make property of medicine, not just evidencewith medical insight in providing care evidence more readily available and based medicine. Study types such to patients. The foundations of E B M further synthesized, and decision aids as N of 1, and large, simple trials are were paved by several key figures: to increase incorporation of patient approaches to reconcile the barriers of Archie Cochrane w h o argued for the values, innovations in E B M as a model evidence extrapolation with the unique summarizing of clinical evidence; Alvan of care are promising (Guyatt et al., conditions of patients. Other recent developments such as the number- Feinstine w h o carved the principles 2004). Future efforts should focus on behind quantitative clinical reasoning; educating clinicians to transfer evidence needed-to-treat and the numberneeded-to-harm are also increasingly Dr. David Sackett w h o pushed for into practice. In addition, policy makers teaching of critical appraisal; and Dr. should be assisted with integrating accepted methods to apply evidence Gordon Guyatt located at McMaster evidence to set clear agendas for the to patients more effectively. These expressions in particular enable the University, w h o published the first academic community. These steps will clinician to simplify evidence at the articlespecificallyonEBMinACPJournal benefit both providers and patients Club in 1991 (Guyatt et al., 2004). alike. â&#x20AC;˘

Guyatt G. & Rennie D (Eds.) Finding the Evidence: Searching for the Answer, pp. 21-22. Users' Guides to BelseyJ.&SnellT. (2003). What is Evidence-Based Medicine? the Medical Literature: A Manual for Evidence-based Clinical Practice. Chicago: American Medical Retrieved February 20th, 2007 from http://www. Association. evidence-based-medicine.co.uk/ebmfiles/Whatisebm. pdf. Montori V., & Guyatt G. (2002). What is Evidence-Based Metabolism Dickersin K., Straus S. & Bero L. (2007). Increasing, not Medicine? Endocrinology and Clinics of North America, 31: 521-26. dictating choice. British Medical Journal, 334: 122. Schardt, C. (2004). Introduction to Evidence-Based Medicine. Retrieved February 20th, 2007 f r o m Guyatt G., Cairns J., Churchill D., Cook D., Haynes B., Hirsh http://www.hsl.unc.edu/services/tutorials/EBM/ J., Irvine J., Levine Ma., Levine Mi., Nishikawa J., whatis.htm & Sackett D. (1992). Evidence-based medicine: A N e w Approach to Teaching the Practice of Medicine. Journal Straus S. & McAlister F. (2000). Evidence-based medicine: of the American Medical Association, 268 (17). a commentary on c o m m o n criticisms. Canadian Medical Association Journal, 163:837-841. Guyatt G., Cook D., & Haynes B. (2004). Evidence based medicine has c o m e a long way. British Medical Journal of the American Medical Directors Association. Journal, 329:990-991. 5(2): 135-137.

REFERENCES

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A n Introduction to Virotherapy THE HERPES SIMPLEX VIRUS AND ADENOVIRUS ARE AT THE FOREFRONT OF VIROTHERAPY - AN APPROACH THAT USES VIRUSES TO DELIVER SPECIFIC GENES OR SELECTIVELY LYSE TUMOUR CELLS. THE PROMISING RESULTS FROM THIS FIELD OF RESEARCH HAVE MANY IMPLICATIONS WHICH INCLUDE A NOVEL WAY OF TARGETING SPECIFIC CANCER CELLS. THIS ARTICLE GIVES A DETAILED BACKGROUND OF THE ABOVEMENTIONED VIRUSES, THE MECHANISMS BY WHICH THEY OPERATE, AND HOW THEY HAVE EMERGED AS PRIME CANDIDATES FOR USE IN VIROTHERAPY.

Siddhi Mathur

V i r o t h e r a p y is a recent strategy that could potentially be used to cure cancer by infecting tumor cells with a virus. Modern virotherapy is n o w being tested in h u m a n s after showing promising results w h e n tested in mice. This paper explores the use of the herpes simplex virus (HSV), and its potential as a cure for breast cancer. However, it is not the only virus undergoing research. Another commonly known virus, the adenovirus, is being explored for its use in the killing of cancerous cells by inducing apoptosis or by the remission of genes that increase cancerous cells' susceptibility to chemotherapy. This paper will discuss two strategies: using viruses to express therapeutic genes to replace ineffective or absent genes, and the other, involving the use of oncolytic viruses to replicate only in tumor cells, and destroy them. The

workings and uses of the adenovirus and the HSV as vectors for gene therapy and oncolytic viral therapy in cancer patients will also be explored.

HSV HSVs are widespread amongst different species, and are host-adapted pathogens. There are two types of HSV: HSV-1 and HSV-2 (Dupont et al., 2008). These two viruses are identical in terms of physical properties; however, they differ in epidemiological characteristics. The HSV virion itself contains a linear double-stranded D N A genome, found inside a protein shell. This shell, also known as the HSV nucleocapsid, is surrounded by a layer of viral protein called the tegument. This layer is

G e n o m e size of potential virus vectors for the nervous system Adeno-associated virus Adenovirus Herpes simplex virus Lentivirus

8,500 35,000 150,000 10,000

base pairs base pairs base pairs base pairs

Table 1: This table compares the size of the HSV to other c o m m o n viruses in terms of base pairs (Latchman, 2001

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"MEDUtylOU 12 enclosed within a lipoprotein envelope containing glycol proteins, which are responsible for the attachment of the HSV to host cells. The most important biological characteristic of HSVs is their ability to permanently infect a host. Despite the host's i m m u n e system, the virus can be reactivated periodically, either spontaneously or by stimuli (Dupont et al., 2008).

HSV as a Vector HSV-1 is one of the viruses most studied as a potential gene therapy vector (Latchman, 2001). Its g e n o m e consists of 152 kilobase pairs of linear D N A and 84 conjugate genes (Beutler et al., 2006). A useful property of HSV is that almost half of the virus'genome can be deleted, yet it can still replicate with efficiency and carry out all necessary processes (Beutler et al., 2006). However, if the HSV needs to be engineered with an amplicon (a small segment of DNA), more than 5 0 % of the virus needs to be left intact. The HSV can either encode the therapeutic gene into its genome, or it can become part of an amplicon delivery system. In the amplicon delivery system, the therapeutic gene is cloned into a eukaryotic plasmid that contains an HSV origin and a packaging signal (Beutler et al., 2006). This process allows the plasmid to replicate as the HSV reproduces with a HSV helper vector (Beutler et al., 2006). Moreover, the employment of the plasmid vector simplifies the manufacturing process and reduces the severity of the effects that live HSV could have (Beutler et al., 2006).

Issue 101 March 2007

VIROTHERAPY WITH TRAI

Engineered adenovirus with tumor-specific promoter links to essential virus gene

NORMAL CELL Infection occurs, but normal cell does not have a switch to turn on viral [ gene. Virus cannot / replicate or kill cell

This image describes transcriptional targeting. specific gene is juxtaposed beside one of the above illustration by a darkly shaded area on th.

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Issue 101 March 2007

\ISCRIPTIONAL TARGETING

Cell bursts, and virus infects and kills other cancer cells

CANCER CELL

Tumor specific promoter j

ii Cancer cell : has switch ! j to turn on j viral | replication j genes j

In this process the snippet of the promotervirus'essential genes. This is shown in the le virus' D N A (Curiel & Nettleback, 2003).

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The second method [Figure 1], involves inserting the therapeutic gene directly into the HSV genome, which can be accomplished by cloning the gene into the plasmid vector using a particular technique that allows the gene to be 'flanked' by specific HSV viral sequences (Latchman, 2001). Further, w h e n the plasmid with the gene is transfected into cells along with HSV DNA, recombination occurs between the viral sequences in the plasmid vector and the corresponding sequences in the virus g e n o m e (Latchman, 2001). This results in the introduction of the new gene into the HSV genome. As mentioned earlier, one of the greatest advantages of using HSV as a vector is its large g e n o m e compared to other viruses being researched for gene therapy, and the large number of unessential genes. These genes, once removed, make room for therapeutic genes. Furthermore, such a characteristic is particularly important because most viruses cannot package large genes (Latchman, 2001). However, HSV can accommodate 30 to 40 kilobase pairs of genetic material after removing its o w n genetic material, especially since the removal of its o w n genetic material does not affect the growth of the virus (Latchman, 2001). HSV will be useful in the future as many cancer therapies require large genes (Latchman, 2001). H u m a n breast cancer cells are particularly sensitive to HSV-1 cytotoxicity (Liu et

Issue 101 March 2007

*M ED WWDH 14 Figure 1: Introduction of foreign D N A into the herpes simplex virus (HSV)-I genome by recombination (Latchman, 2001).

ADENOVIRUS Cut and insert foreign D N A

Plasmid with viral gene IS \\l

iw\\

Recombination

Introduce into cell with wild-type virus

*\â&#x20AC;&#x201D;*M

Virus with foreign gene and inactivated virus gene

al., 2001). The HSV oncolytic vectors are suitable for breast cancer tumor therapy because the mutant viruses replicate in the cells with uncontrollable cell division only, and not in the normal cell tissue (Liu et al., 2001). For example, cancer killing vectors like G207 are created by inserting foreign genes and mutations into the virion's original g e n o m e (Harvard Medical School, 2005). The G207 vector is also based on the removal of the genes that allow it to withhold replication in non-dividing cells. Since these genes are not essential for replication in rapidly dividing cells, the virus replicates only in cancer cells. The G207 vector, originally meant for brain tumors, has proved useful in the treatment of multiple h u m a n tumors including breast cancer (Liu et al., 2001). Further research is looking into the use of the G207 HSV vectors to remove breast cancer tumor cells from bone marrow (Liu et al., 2001). Moreover, the G207 vector is very sensitive to antiviral drugs like acyclovir and gangcyclovir, which means that if the vector were to replicate uncontrollably, it could easily be controlled with the help of these drugs (Liu et al., 2001). This feature, along with the ability of HSV to replicate only in tumor cells, adds to the safety of this treatment option.

The adenovirus, a cause for the common cold, is under intense research and has been d e e m e d useful in the development of virotherapy for the treatment of malignant tumors (Curiel & Nettleback, 2003). Further, the adenovirus is particularly helpful because it has been studied for years by scientists trying to find a cure for the c o m m o n cold. A setback that researchers face is that m a n y people have been exposed to adenoviruses and carry the antibodies against them. Therefore, injecting shots of the adenovirus as cancer therapy can cause severe flu-like symptoms prompting the body to annihilate the dose given, thereby inhibiting the therapy (Curiel & Nettleback, 2003). Nonetheless, the body's response to the virus ensures that its replication remains controlled (Curiel & Nettleback, 2003).

Adenovirus as a vector The adenovirus is comprised of a 20-sided protein case or capsid, containing D N A and 12-protein arms.The adenovirus is different from retroviruses used in gene therapy since it does not integrate its D N A into infected cells .To ensure the accuracy of adenoviruses, researchers are working on two mechanisms: transductional targeting and transcriptional targeting (Curiel & Nettleback, 2003). Transductional targeting incorporates the ability of the virus to identify and enter tumor cells. This is an important strategy as the adenovirus generally penetrates normal tissue cells instead of tumor cells . This can be changed by attaching special antibodies onto the arms of the virus like a socket wrench and these antibodies attach to only tumor-specific proteins. Once attached, the virus is engulfed into the cell, where the viral capsid enters the nucleus through a pore and injects its o w n D N A (Curiel & Nettleback, 2003). Once copies of the viral D N A have been made, proteins are synthesized to form many more adenoviruses. The virus then causes the cell to burst, allowing all the adenoviruses to leak out Curiel & Nettleback, 2003). Transcriptional targeting involves placing a snippet of D N A called a tumor-specific promoter next to one of the adenovirus' essential genes (Curiel & Nettleback, 2003). This promoter acts as an 'on' switch that permits the genes to function only in cancer cells. These engineered viruses can enter any cell in the body, but they only reproduce in cancer cells (Curiel & Nettleback, 2003). However, w h e n

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15 ,AMEMJL\JQf{

Issue 101 March 2007 they enter a tumor cell, the tumor-specific promoter allows them to be copied and thousands of copies result as the new virions break out of the tumor cells and spread (Curiel & Nettleback, 2003). The adenovirus infects cells and then induces them to enter the'S' phase of the cell cycle (Bischoff et al., 1996). The h u m a n gene E1B codes for a protein that inactivates the tumor-suppressing cellular protein p53 (Bischoff et al., 1996). The E1B-deleted adenovirus replicates only in p53 deficient cells (Bischoff et al., 1996). Injections of the El Bdeleted adenovirus significantly reduced the size of the tumors in mice being tested (Bischoff et al., 1996). Further, in mice co-infected with adenovirus and HSV, improved results were observed in the treatment of colon cancer (Blaese, Morris & Wildner., 1999). The rationale behind this treatment is that the adenovirus comprises the suicide genes while HSV provides a safety mechanism that will abort the infection if uncontrolled growth of the virus occurs (Blaese et al., 1999).

CONCLUSION Individuals previously infected with adenovirus or HSV will have acquired an immunological response to either virus.This leaves very little room for researchers to develop a vaccine that uses these viruses, as they cannot predict h o w the patient's i m m u n e system will react. More research is required before utilizing it as a cure. Thus far, this technology has been tested on mice, while other animal models have been created. Phase I and II h u m a n trials have also been conducted. Progress has been m a d e in these models, tumor regression has been observed, and translation of the finalized treatment to humans m a y be expected in the near future.ES2

REFERENCES Using an Attenuated Replication-competent HSV in Curiel, D. Nettleback , D. (October 2003). Tumor-Busting. H u m a n Hematopoietic Stem Cell Transplantation. Cancer Research. 61, 3009-3015. Scientific American, 68-75 Dupont, Herbert, Humes, Gardner, Laurence et al. (Ed.). (2008). Kelley's Textbook of Internal Medicine. Philadelphia. PA: Lippincott Williams and Wilkins.

Bischoff J. R., Kirn D. H., Williams A., Heise C, Horn S., e (1996).An adenovirus mutant that replicates selectively in p53-deficient h u m a n tumor cells. Science, 274,373376.

Beutler, Ernest, Kaushansky, Kenneth, Kipps et al. (2006). Williams Hematology. United States of America: Blaese, M. Morris, J. Wildner, O. (1999). Therapy of Colon Cancer with Oncolytic Adenovirus Is Enhanced by the McGraw Hill. Addition of HSV-thymidine kinase. Cancer Research. 59, 410-413. Latchman, D (2001 ).Gene Therapy with HSVVectos: Progress and Prospects for Neuroscientist. 7, 528-537.

Neuroscience.

The

Molecular Neurosurgery Laboratory - Gene Therapy. (2005). Retrieved January 28, 2007, from Harvard Liu X., Martuza R., M a z u m d e r A ., Meehan K., Rabkin S., et Medical School: Richard B. Simches Research Centre W e b site: http://btrc.mgh.harvard.edu/MNL.htm al. (2001).Biological Purging of Breast Cancer Cells

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"MEGUVylDfi 16

Advances in Molecular Cytogenetic Technology: Comparative Genomic Hybridization (CGH) COMPARATIVE GENOME HYBRIDIZATION (CGH) is A TECHNIQUE USED

TO VISUALIZE DIFFERENCES BETWEEN TWO GENOMES. IT HOLDS PROMISE FOR IDENTIFYING GENES THAT ARE AMPLIFIED OR DELETED - USEFUL F Mark Adams

FINDING SPECIFIC SYNDROMES OR EXAMINING DIFFERENCES THROUGHOU THE ENTIRE GENOME. THIS ARTICLE DISCUSSES THE DEVELOPMENT, MECHANISM, AND APPLICATION OF CGH. DEVELOPMENTS LEADING U P TO

COMPARATIVE G E N O M E HYBRIDIZATION

A new technology called Comparative Genome Hybridization (CGH) has a resolution power equivalent to FISH. Although C h r o m o s o m a l abnormalities are one cause of phenotypic C G H is limited to using metaphase chromosomes, it has m a n y differences between normal and affected individuals. other advantages (Shaffer & Bejjani, 2004). C G H compares The technique of chromosomal banding was developed differences in two different genomes; D N A is extracted from in the early 1970s to identify these abnormalities (Shaffer both the test subject and a normal reference subject. The two & Bejjani, 2004). Banding uses chemicals that alter the samples are then labeled, usually green (cyanine 3, or Cy3) and colorimetry of D N A pairs to produce differently stained regions red (cyanine 5, or Cy5). The ratio of the two fluorochromes on on chromosomes. These regions appear as bands of varying the metaphase chromosomes are then compared (Spiecher & shades of grey under light or fluorescence microscopy. This Carter, 2005). To illustrate its application, consider a red test allows the detection of structural rearrangements such as sample and a green reference sample. If a region is amplified translocations, deletions, duplications, polymorphic variations, in the test sample, the corresponding region of hybridized or ploidy differences (Shaffer & Bejjani, 2004). However, with chromosome appears red. However, if a region is deleted in time it has become evident that routine banding methods the test sample, the corresponding region of the hybridized cannot uncover all abnormalities, as only rearrangements chromosome would appear green. The ratio of the greater than 10 megabases can be reliably detected " C G H IS test to reference fluorochromes is quantified by (Spiecher & Carter, 2005). As a result, numerous E S P E C I A L L Y a computer m a p p e d to each chromosome pair technologies have been developed to provide and visualized with a digital image (Spiecher USEFUL IN a higher resolution in the delineation of subtle & Carter, 2005). DETECTING DELETIONS, rearrangements. The major advantage of this Molecular cytogenetics was DUPLICATIONS, technology is that it does not require a prior developed in the 1980s and is based on the NON-RECIPROCAL hypothesis of a genetic defect, and can thus hybridization of D N A probes to target D N A TRANSLOCATIONS, identify regions of genetic imbalance. C G H (Levsky & Singer, 2003). These probes are A N D G E N E is especially useful in detecting deletions, labeled using fluorochromes for a variety of AMPLIFICATIONS" duplications, non-reciprocal translocations, and different regions of the chromosome, including gene amplifications throughout the entire g e n o m e the centromere, telomere, specific genes, or even the (Spiecher & Carter, 2005). However, C G H does c o m e with entire chromosome (Shaffer & Bejjani, 2004). Application of limitations such as failure to detect balanced translocations fluorescence in-situ hybridization (FISH) in conjunction with routine banding vastly improved the detection of changes in and inversions due to incomplete genomic information. Also, D N A (Albertson & Pinkel, 2003). FISH is a popular molecular C G H analysis does not provide possible sites of imbalance, thus cytogenetic technique that hybridizes the labeled probe to the locating the site of the imbalance can be a concern without target DNA, through a series of denaturing and re-annealing the availability of routine cytogenetics methods (Spiecher & steps. Currently there are commercially available probe kits for Carter, 2005). C G H has been improved through use with microarrays. c o m m o n aneuploidies, specific deletions, duplications, fusion gene rearrangements in cancers, and telomeric regions (Shaffer For Array C G H (aCGH), large numbers of m a p p e d clones (cDNA, & Bejjani, 2004). Though this technology provides a higher Bacterial Artificial Chromosomes, PCR-generated sequences, resolution of 5 to 10 megabases, the largest limitation is that or oligonucleotides) spotted onto a glass slide are used instead one must decide beforehand on specific regions in which to of metaphase chromosomes. This increases the resolution of screening for gains or losses of genomic copy numbers so that look (Shaffer & Bejjani, 2004).

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17 ^MEDVUJG/t

Issue 101 March 2007 the resolution is only limited by the size and density of the target sequence. Typically, one clone is used per megabase (Carter & Vetrie, 2004). The test and reference genomes are labeled and co-hybridized onto a microarray (Shaffer & Bejjani, 2004). The array is imaged and the fluorescence intensities are calculated for each m a p p e d clone, with the resulting ratio reflecting the differences in D N A copies (Shaffer & Bejjani, 2004). Computer imaging reveals a yellow hybridization colour for all clones that are in equal proportion between the test and reference. Clones that are deleted in the test D N A will appear green, and those duplicated will appear red. A computerized plot of the ratio between test and reference is m a d e to reveal dosage differences. It is visualized as a deviation of the ratio from zero (Shaffer & Bejjani, 2004).

Array C G H is advantageous because of its higher resolution and dynamic range, and there is direct mapping of aberrations to the g e n o m e sequence because the alterations are immediately linked to genomic markers via the clones used (Albertson & Pinkel, 2003). a C G H is also advantageous because it can be automated for high-throughput application, and it has a low false-positive count (Shaffer & Bejjani, 2004). There is also wide flexibility with the type of array available, ranging from whole-genome arrays to specialized arrays for specific diseases (Spiecher & Carter, 2005).The highest resolution a C G H is provided by oligonucleotide arrays, produced by spotting oligonucleotides onto a slide, or synthesizing them directly onto the glass. This allows for a resolution as specific as 15 to 20 kilobases (Albertson & Pinkel, 2003). It is even possible to Figure 1:

A Cloned h u m a n D N A (BAC/PAC)

Arrayed

gooooDOoa 0DDOD00DO DDDDDnnnD 0D000DD0D 000000000 000000000 D0DDD0DDD DDDDDODDD OOO0O000D 0DDDDDDDD 00000000D ODDDaDDDD DDDDDDODD â&#x20AC;˘naDDDODD clones DDDDDDODD DDDDDDDDD

DDDDDDODD DDDDDDODD DDDDDDODD DD0DDD0DD DODODDDaO DDDDDDDDD D0D0DDDDD DDDDDDDD0 0DDD0D0DD 0D0D0DDDD 0DODDDDDD DD0D0DDDD DDDDDDDDD DDDDDDDDD DD0DDDDDD DDDDDDDDD

A. Clones of all the genes on a c h r o m o s o m e or entire g e n o m e are printed onto a glass microscope slide (arrayed). The right side shows h o w they can be stained to s h o w the morphology and placement of each "spot" of the cloned D N A B. The reference (left) and test (right) are labelled with different fluorochromes, and then mixed o n the array. C o m p u t e r imaging shows a yellow hybridization colour for the clones that are equal in proportion, green for those genes deficient in the test, and red for those in excess in the test D N A (lower left). A plot of ratio between the reference and test D N A for each clone showing dosage differences (lower right) (Shaffer & Bejjani, 2004).

Test genomic DNA

Control genomic DNA

B [â&#x20AC;˘111 s

. ^

C h r o m o s o m a l position

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Issue 101 March 2007

'UEDliWH 18 find single nucleotide polymorphisms (SNP) using SNP arrays, which are high-density oligonucleotide-based arrays. These are useful in identifying Loss of Heterozygosity which is the loss of a single allele at a given locus as a result of genomic mutations (Spiecher & Carter, 2005). The primary drawback of aCGH is the cost; routine testing of the equipment has been quoted at $90 000, and each array costs more than $1 200 in some cases (Kolomietz, 2006). Currently C G H has been used for the analysis of gains or losses in tumours, but remains largely a tool for research purposes. C G H has also been important in identifying the presence and levels of normal genomic variation, which are assumed to be responsible for individual differences in gene expression, phenotypic variation, and susceptibility to disease (Spiecher & Carter, 2005).

APPLICATION TO THE REAL WORLD There are no genetic techniques that can be used to find every variation. For example, routine G-Banding has been used as the standard for decades in screening for polyploidy, aneuploidy, or rearrangements. However, its low resolution makes it challenging to detect microdeletions, microduplications, and subtle rearrangements; it is also reliant on the adequate preparation and morphology of the chromosomes. FISH can be quite effective for clinical laboratories in identifying specific syndromes, provided that

FISH probes are commercially available (Spiecher & Carter, 2005). C G H is very useful for searching the entire g e n o m e and for indicating the presence of genetic abnormalities, but remains very expensive, allowing only well-funded labs to utilize C G H technology. Each technique described seems to be useful under different circumstances, while lacking in terms of resolution or economics. At this time, it is best to combine techniques in order to provide a comprehensive analysis, if the tests are available. An example given by Speicher & Carter (2005) illustrates this point best using the example of a child exhibiting mental disability and dysmorphic features due to an unknown chromosomal rearrangement. First, G-banding was able to show a complex chromosomal rearrangement, but could not identify the structural chromosomal rearrangements. FISH could identify the rearrangement involving the chromosomes 2, 5, 6, 8, and 14, but could not tell anything about the imbalance. Lastly, array C G H was able to identify four genomic deletions, and allowed direct mapping of the deletion breakpoints onto the reference. The number of genes involved could be determined using internet based g e n o m e browsers (Spiecher & Carter, 2005). With strategies similar to this, it is plausible that the origin of some genetic disorders can be confirmed. Also, the possibility of developing a more cost efficient technology will allow genetic disorders to be diagnosed in the most economic manner under the tight restrain of health care dollars. E9

REFERENCES Albertson, D. & Pinkel, D. (2003). Genomic micro arrays inShaffer, L. & Bejjani, B. (2004). A cytogenetist's perspective h u m a n genetic disease and cancer. H u m a n Molecular on genomic microarrays. European Society of H u m a n Genetics. 12(2), 145-152. Reproduction and Embryology,10(3), 221 -226. Carter, N. &Vetrie, D. (2004). Applications of genomic micro Spiecher, M. & Carter, N. (2005). The new cytogenetics: arrays to explore h u m a n chromosome structure and Blurring the boundaries with molecular biology Nature function. H u m a n Molecular Genetics. 13(2), 297-302. 6, 782-792. Kolomietz, E. (2006, May 19). Array CGH: Expanding ACKNOWLEDGEMENTS: resolution of cytogenetics analysis. Paper presented at the 2006 Great Lakes Chromosome Conference, Toronto, Project Supervisor Ont. Viola Freeman Assistant Professor LevskyJ.&Singer,R. (2003). Fluorescenceinsituhybridization: Dept. of Pathology and Molecular Medicine, past, present and future. Journal of Cell Science. 116, McMaster University 2833-2838.

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19 "MEUM/JH

Prostate Cancer and Robotic Surgery

ROBOTIC-ASSISTED LAPAROSCOPIC PROSTATECTOMY (RALP) I CURRENTLY BEING USED BY SEVERAL HOSPITALS IN CAN ADA TO REMOVE CANCEROUS PROSTATE GLANDS. H0WEVER,ITS BENEFIT THUS FAR HAVE BEEN MINIMAL WHILE COSTS HAVE BEEN HIGH. THIS ARTICLE IS COMPREHENSIVE REVIEW OF PROSTATE CANCER ASWELL AS AN ASSESSMENT OF PAST AND PRESENT METHODS OF MANAGEMENT.

Russell Fernandes

It is estimated that there will be 20 700 n e w cases of prostate the prostatic urethra, which is a tube that runs from the bladder cancer in Canadian m e n this year. Prostate cancer accounts for to allow for urine flow. The peripheral zone is located at the 4 200 deaths and ranks third in cancer mortalities. Given the back of the prostate gland and is therefore the closest to the incidence of prostate cancer, it is helpful to know h o w it begins, rectum. The peripheral zone also contains most of the secretory when to seek action, and what surgical options are available glands and is also the most c o m m o n location of prostate cancer. (Canadian Cancer Society, 2006). The prostate capsule is a m e m b r a n e that surrounds the gland (Grimm etal., 2003). Prostatic secretions account for approximately a quarter ANATOMY AND PHYSIOLOGY of the volume of semen and help to increase the motility and viability of the sperm. Prostate-specific antigen, also called PSA, The prostate gland is located inferior to the bladder and anterior to the rectum. The prostate is about the size of a golf ball and is an important proteolytic enzyme. PSA helps to break d o w n the is divided into four zones called the transition, central, anterior clotting proteins of the seminal vesicles to make the ejaculate and peripheral zones (Figure 1).The transition zone surrounds more fluid w h e n it enters a w o m a n during sexual intercourse (Tortora et al., 2003).

Bladder

Bladder Seminal vesicle

Prostate Urethra

ntral Zon insition Zon ipheral Zo

Front V i e w Figure 1: Prostate zones (Prostate Research Campaign UK, 2004).

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"MEDUUIMl 20

indicate that adults w h o rapidly gain weight start secreting higher levels of growth factors, which can induce prostate cancer growth. African-American m e n are known to have higher testosterone levels, especially before the age of forty, compared to other ethnic groups (Grimm et al., 2003). SCREENING TESTS Although most men should start getting screened from the age offiftyonwards, African-American men, and individuals with a family history of prostate cancer, should start being screened around the age of forty-five. The two main screening tools include the digital rectal exam (DRE) and the measurement of free serum PSA. The DRE involves the doctor placing a gloved finger into the rectum to check for physical irregularities of the prostate, however, these do not always indicate the presence of prostate cancer (CDC, 2006). The PSA test m a y be more useful than the D R E because it can be hard to find nodules. PSA levels are measured according to nanograms (ng) per milliliter (ml) of serum. It is normal for some PSA to enter the bloodstream. The normal upper limit was considered to be 4.0 ng/mL but recent evidence suggests that normal levels for younger m e n Figure 2:Tumour has penetrated prostatic capsule and may invade seminal should be between 2.5 - 3.0 ng/mL. Elevated PSA levels m a y vesicles (Oncology Channel, 2005). indicate cancer, but can also include other non-cancerous conditions such as benign prostate hyperplasia, inflammation, W H A T CAN G O W R O N G ? and infection. A biopsy of the prostate is another method of It is common for the prostate to enlarge with age. In fact, thescreening for cancer, which involves using a needle to obtain samples of prostatic tissue for analysis (Grimm et al., 2003). transition and central zones can grow after the age of forty. Prostate conditions may include benign prostatic hyperplasia (BPH), prostatitis, and prostate cancer. BPH refers to a "non CANCER GROWTH AND SPREAD cancerous enlargement of the prostate," which can compress the prostatic urethra and impede urination. Other symptoms When discussing prostate cancer, it is assumed that the m a y include the sensation of a partiallyfilledbladder or the term refers to adenocarcinomas, which are cancers that need to urinate more frequently. Symptoms of prostatitis arise from secretory cells of certain organs (Figure 2). In this (inflammation of the prostate) may resemble those of BPH, and case, adenocarcinomas c o m e from the ducts of the prostate can also include fever, perineal pain and painful ejaculations. gland. T w o rare forms of prostatic cancers include urothelial Prostate cancer is the most serious prostatic disease and refers cell carcinomas (UCC), which are derived from cells that line to the "uncontrolled growth of cells that line the ducts of the the bladder and urethra. The second type of a rare prostatic prostate gland." Recall that prostate cancer typically occurs in cancer is known as a sarcoma, which arises from the prostate's the peripheral zone of the prostate (Grimm et al., 2003). muscular and connective tissue (Grimm et al., 2003). RISK FACTORS Three risk factors for prostate cancer include age, family and race. M e n should get regular prostate tests, as the risk of getting prostate cancer increases with age. The screening process is even more important if an immediate family m e m b e r also had prostate cancer. African-American m e n are known to have the highest risk not only of developing prostate cancer, but also of its emergence earlier in life. There is no conclusive study to illustrate w h y African-American m e n are at higher risk, but speculation includes socioeconomic factors, diet and genetics (American Cancer Society, 2006). A number of substances can promote the growth of prostate cancer such as testosterone and h u m a n growth factors. Laboratory tests

Fortunately, prostate cancer usually grows slowly, but like other cancers, it m a y grow and spread at a fast rate. If it does spread, it does so via the blood and lymphatic systems. history There are three ways to assess the growth rate of prostate cancer. First, one can measure the PSA velocity, which refers to h o w fast the PSA levels are rising. PSA velocities are agespecific and race-specific. If PSA levels rise at more than 0.75 ng/mL in under one year, further investigation is needed. Second, one can measure the Gleason grades, which are the most c o m m o n way of assessing the severity of prostate cancer (Prostate Cancer Research Foundation, 2005). Third, physical examinations and radiological tools such as MRI and bone scans can help to analyze the spread of the cancer (Grimm et al.,2003).

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Issue 10 | March 2007 W H E R E D O E S PROSTATE CANCER SPREAD? Prostate cancer can penetrate the prostate capsule and can even m o v e into the seminal vesicles. Cancer cells can spread into the pelvic region by entering lymph nodes in the pelvis. Prostate cancer cells have an affinity for growing in bones, usually in the spine, pelvis, or long bones such as the femur and humerus (Tewari et al., 2004).

TREATMENT AND TECHNOLOGY Open (non-robotic) surgical procedures include the retropubic approach, where an incision is m a d e in the abdomen, and the perineal approach, where an incision is m a d e between the scrotum and anus. The purpose of both procedures is to remove the prostate, which is referred to as a prostatectomy. Pure laparoscopic radical prostatectomy involves removal of the prostate gland, seminal vesicles and lymph nodules through small abdominal incisions. It is only performed in a few centres around the world because of its technical challenges, including St. Joseph's Hospital in Hamilton, Ontario (Dr. Matsumoto, personal communication, January 9, 2007). Robotic-assisted laparascopic prostatectomy (RALP) has the same goal as open surgery and the pure laparoscopic approach - the

21 "MEDIULVMi removal of the prostate gland (M.D. News, 2006). However, the main advantage of RALP is that it can overcome some of the steep learning curves associated with laparoscopic radical prostatectomy (Dr. Matsumoto, personal communication, January 9,2007).

The camera's magnification capability improves the surgeon's view of the operativefield(Hozneketal., 2003). Just like open surgery, the prostate, seminal vesicles and lymph nodes are assessed in order to determine the spread of cancer, (Intuitive Surgical, 2005). RALP follows the same surgical principles as radical retropubic OVERVIEW OF TECHNOLOGY prostatectomy (RRP). The prostate is separated from the bladder neck and The Intuitive Surgical's "da Vinci Surgical the seminal vesicles are removed. The System" is an exciting n e w development. pedicles (prostatic arteries) are the main The da Vinci Surgical System is another blood supply to the prostate and are step forward in thefieldof minimally closed with clips to prevent bleeding. invasive surgery. The system consists A vesicouretral anastomosis (between of a console and a patient-side robotic bladder neck and urethra) takes place system. The surgeon sits at the console, and is the most challenging part of the which has a screen that provides a full 3 D surgery (Ong et al., 2004). The prostate view of the operativefield.The surgeon is placed in an entrapment bag when uses the controls at the console, which using RALP, and then an umbilical translate hand motions into robotic incision is enlarged to accommodate motions, carried out by four robotic arms removal of prostate with the robotic (Figure 3).The robotic arms are equipped arm. Finally, the pneumoperitoneum with "Endowrist technology," which are (filling of the a b d o m e n with an inert instruments that can m o v e like h u m a n gas to tamponade blood vessels) is wrists (Intuitive Surgical, 2005). released and the sites where the robotic arms entered the patient are closed. PROCEDURE DESCRIPTION RALP using the da Vinci Surgical System consists of making five ports (or entry points) in the patient's abdomen. Four of the ports are used to allow the four robotic arms to enter the patient's body and the last port is used for the camera for visualization at the surgeon's console.

Figure 3: The da Vinci Surgical System with surgeon console at left and patient in middle (Hatton Institute, 2005).

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OUTCOMES AND ADVANTAGES There are debates with regard to whether RALP is superior to RRP partly because there are not m a n y balanced prospective studies to m a k e an adequate comparison (Bhayani et al., 2004). RRP is not associated with a lot of post-operative pain nor does it require large incisions. RALP is supposed to offer less pain and less scarring in the post-operative period, which raises the question as to whether the marginal improvements using the da Vinci system are worth the cost of the system and the extra training (Webster et al., 2005). The use of the da Vinci Surgical System m a y include improvements in certain outcomes. There is emerging evidence that intraoperative bleeding may be lower using RALP because of the establishment of a pneumoperitoneum and the precision of the robotic arms. Less bleeding in the surgical area contributes to an improved and clearer operativefieldfor the surgeon (M.D. News, 2006). Lastly, the duration

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Issue 101 March 2 0 0 7

of hospital stay between RRP and RALP patients is almost identical (Tewari et al., 2003). F e w centres in the U.S. actually profit from using the da Vinci system because of the high cost of the technology. Pure laparascopic surgery is probably m o r e cost-effective than o p e n and RALP approaches (Dr. Matsumoto, personal communication, January 9, 2007).

the technology for the da Vinci System keeps advancing. For example, Endowrist scissors with electrocautery capability have been produced to minimize the n u m b e r of instrument exchanges. Furthermore, the use of ultrasound and electrical stimulation devices m a y assist in locating and avoiding d a m a g e to cavernous nerves, to minimize a decline in erectile function (Intuitive Surgical, 2005).

FUNCTIONAL OUTCOMES CONCLUSION Prostate cancer patients will most likely deal with urinary incontinence and erectile dysfunction after surgery. The evidence is mixed as to whether RALP improves a patient's return to continence. The reasoning is that an excellent visualization of the operative field combined with the precision of the da Vinci Surgical System allows surgeons to meticulously remove the prostate without injuring neighbouring musculature ( M e n n o n et al., 2004). The cavernous nerves, located within the neurovascular bundle, are the nerves that control erectile function. O n c e again, n o published results indicate whether RALP is better than RRP in preserving erectile function outcomes after surgery. However,

The prostate gland is responsible for promoting the viability and motility of sperm and the most serious form of prostatic disease is prostate cancer.Technological advances, such as the da Vinci Surgical System, m a y help urologists overcome the technical challenges of laparoscopic radical prostatectomy and m a y offer improved outcomes for patients, especially in terms of incontinence and potency. Despite a lack of studies to substantiate claims that the da Vinci System definitely offers better surgical outcomes, current literature discusses potential benefits of RALP in terms of technological a d v a n c e m e n t s . ^

REFERENCES

M.D. News. Improving the Experience of Prostate Cancer Surgery. American Cancer Society. (2006). Retrieved Apr. 9, 2006, from What2006. Are The Risk Factors for Prostate Cancer? W e b site: http://www. cancer.org/docroot/CRI/content/CRI_2_4_2X_What_are_the_ Menon, M., et al. (2004). The technique of apical dissection of the prostate and urethrovesical anastomosis in robotic radical risk_factors_for_prostate_cancer_36.asp?sitearea=. prostatectomy. BJU Int 93:715-719. Bhayani SB., Pavlovich CR, Strup SE., et al. (2004). Laparoscopic radical prostatectomy: A multi-institutional study of conversion Oncology Channel. (2005). Retrieved Apr. 6, 2006, from Prostate Cancer Staging Systems W e b site: http://www.oncologychannel. to open surgery. Urology 63:99-102. com/prostatecancer/stagingsystems.shtml. Canadian Cancer Society. Canadian Cancer Statistics 2006. Retrieved April 11, 2006, from http://www.cancer.ca/vgn/images/portal/ Ong, AM., Su, LM., Varkarakis, I., et al. (2004). Nerve sparing radic prostatectomy: effects of hemostatic energy sources on the cit_86751114/31/21/935505792cw_2006stats_en.pdf.pdf recovery of cavernous nerve function in a canine model. J Urol 172:1318-1322. CDC. (2006). Retrieved Apr. 10,2006, from Prostate Cancer Screening W e b site: http://www.cdc.gov/cancer/prostate/decisionguide/. Prostate Cancer Research Foundation. (2005). Retrieved Apr. 9, 2006, from Gleason Grade W e b site: http://www.prostatecancer.ca/ Farnham, S. et al. (2006). Intraoperative blood loss and transfusion requirements for robotic-assisted radical prostatectomy versus english/prostate_owners_manual/living/diagnosis/gleason/. radical retropubic prostatectomy. Urology, 67(2). Prostate Research Campaign UK. (2004). Retrieved Apr. 10, 2006, Grimm, P., Blasko, J., and Sylvester, J. The Prostate Cancer Treatment from W e b site: http://www.prostate-research.org.uk/index. Book. McGraw-Hill, 2003. htm?aboutprostate/aboutprostate.htm~main.

Tewari, A. et al. (2004). Nerve sparing robotic prostatectomy: a nove Hatton Institute. (2005). Retrieved Apr. 9, 2006, from http://www. and minimally invasive treatment of prostate cancer. Prostate hattoninstitute.com/daVinci_Surgical_System.aspx. Cancer Research Institute, 7(4). Hoznek A., Antiphon P., and Borkowski T. (2003) Assessment of surgical technique and perioperative morbidity associated with Tewari et al. (2003) A prospective comparison of radical retropubic extraperitoneal versus transperitoneal laparoscopic radical and robot-assisted prostatectomy: Experience in one institution prostatectomy. Urol 61:617-622. BJU Int 92:205-210. Intuitive surgical. (2005). Retrieved Apr. 7, 2006, from http://www. Tortora, G., & Grabowski, S. (2003). Principles of anatomy and physiology. 10th ed. Hoboken, NJ: John Wiley & Sons, Inc. intuitivesurgical.com/products/index.aspx. Mayo Clinic Staff. Prostate Cancer. Retrieved April 8, 2006, from Webster, T. et al. (2005). Robotic assisted laparoscopic radical http://www.mayoclinic.com/health/prostate-cancer/DS00043/ prostatectomy versus retropubic radical prostatectomy: a DSECTION=1 prospective assessment of postoperative pain. J Urol, 174(3).

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Issue 101 March 2007

23 'MEDIWJLIH

MedQuiz Have you read all the articles? Test yourself and see h o w well you understood the articles by answering the questions below.

1. The virus with the largest usable genome is

a. b. c. d.

a. lentivirus b. adenovirus c. herpes simplex virus d. Adeno-associated virus e. spumavirus

Which of the following is not limited to the use of metaphase c h r o m o s o m e s for analyzing phenotypic differences? routine G-Banding FISH Molecular Cytogenetics Comparative G e n o m e Hybridization agarose gel electrophoresis

6. Array CGH is not capable of which of the following?

2. The two strategies of infecting a host used by the adenovirus are called a. b. c. d.

trascriptional targeting and the amplicon delivery system transductional targeting and transcriptional targeting transductional targeting and the amplicom delivery system inserting the therapeutic gene into the virus' g e n o m e and the amplicom delivery system e. inserting the therapeutic gene into the virus'genome and the transcriptional targeting

a. b. c. d.

providing information as to the ploidy or location of rearranged sequences detecting g e n o m e duplications finding differences in exact single nucleotide polymorphisms detecting gene amplifications

7. a. b. c. d.

Evidence-based medicine places emphasis on pathophysiological knowledge clinical expertise medical literature community health

3. Which of the following is not a way to assess the growth of prostate cancer?

8. A randomized control trial with good methodology will include all of the following except:

a. b. c. d.

gleason grades physical examinations and radiological tools (e.g. MRI) PSA levels digital rectal exam

4. Which of the following bones does prostate cancer have an affinity for growing in? I. Femur II. IV. Humerus V. a. b. c. d.

Spine Tibia

II. Fibula

I, IV, V Ill, II, IV I, II, IV II, III, IV

allocation concealment randomization loss to follow-up sufficiently large sample size

9. Midday naps may help to reduce the risk of which disease? a. cervical cancer b. breast cancer c. Rett Syndrome d. corunary disease p' yye'D'D'p'p'D :SJ9MSU\/

Back Row (Left to Right): Navpreet Rana, Amandeep Rai, Harjot Atwal, Harman Chaudhry, Ran Ran Middle Row (Left to Right): Sarah Mullen, Siddhi Mathur, Jaqueline Ho, Stephanie Low, Crystal Chung, Alexandra Perri Front Row (Left to Right): Jonathan Liu, Tyler Law Absent: Jeannette So, Fify Soeyonggo, Sharma Sud Photo By: Jeffrey Chan