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When lizards are attacked, they have the remarkable ability to detach their tails from their body in order to confuse their enemy, and then, to grow it back. If a salamander gets its leg chopped off, it can regenerate another one in a matter of weeks. So why can't humans?

From an evolutionary standpoint, it would be energetically wasteful to regenerate a body part that is not necessary for survival, like a finger. Conversely, if an important organ like the heart were significantly damaged, the individual would likely not survive long enough for regeneration to actually take effect. Instead, much of our bodies' effort seems to have gone into wound healing, which actually inhibits potential cell regeneration. In 1974, Dr. Cynthia Illingworth found that young children could regenerate fingertips, but only if their wounds were left open rather than surgically re-covered with skin. In addition, studies in mice have shown that the formation of scar tissue blocks cell signaling necessary for regeneration. When salamanders lose their limbs, instead of covering the wound, cells near the site of the injury de-differentiate and form a group of cells collectively known as a blastema. They can then re-differentiate and build the lost structure, but the cells do not exhibit full pluripotency; instead, old skin cells become skin cells and former bone cells become bone once again. The inability of many higher-order species to undergo this process may be merely one explanation as to why regeneration in those species is rare.

Though humans do not have a great capacity for regeneration, the liver is able grow back from around 25% of its tissue. Research has suggested that this is achieved through the proliferation of cell division, rather than reversion back to an embryonic state. A recent study has discovered a mechanism for the regeneration of damaged tissue in the kidneys; interestingly enough, it occurs via the immune system.

Reference: Cincinnati Children's Hospital Medical Center. "Scientists Discover Molecular Pathway for Organ Tissue Regeneration and Repair." ScienceDaily 16 February 2010. 17 February 2010 <http://www.sciencedaily.com­ /releases/2010/02/100215174134.htm>.

Linda Le is a contributing writer on biomedical research to TuftScope for Spring 2010.

Reduction in Salt Intake Could Lead to Major Decreases In Medical Expenditures and Coronary Deaths

Reviewed by: Caroline Melhado

The New England Journal of Medicine published a study stating a decrease in 3g of salt per day for every individual in the US could lead to a drastic decrease in the prevalence of Coronary Heart Disease (CHD), stroke, myocardial infraction and death from these causes.

The study used a computer model, CHD Policy Model, to study the prevalence and mortality of CHD of a variety of ages and demographics within the US. Using the data from multiple studies correlating the effect of salt on systolic blood pressure researchers were able to compare the impact of salt intake to a variety of health effects. They determined that a reduction in salt intake by 3 grams daily was a more effective way to prevent CHD, stroke and myocardial infraction than would a 50% reduction in smoking, a 5% decrease in body mass index and some treatments of hypertension. The study showed that a decrease in salt intake would affect both white, non-white, men and women.

The salt intake reduction of 3 grams would save an estimated $10 billion and $24 billion in yearly healthcare costs. According to the study it would also reduce the number of new cases of CHD by 60,000 to 120,000, stroke by 32,000 to 66,000, and myocardial infarction by 54,000 to 99,000 annually. This would lead to a reduction in deaths from these three sources by 44,000 to 92,000 a year. Researchers suggest that the cost-effectiveness of a state wide initiative to lower salt intake would save money in comparison to the high medical costs that the US's salt dense culture creates.

Caroline Melhado is the 2009 - 2010 Research Highlights Editor.

Reference: www.nejm.org January 20, 2010 (10.1056/NEJMoa0907355)

No Conclusion Reached on Insulin's Relation with Cancer Risk

Priya Larson

If you are diabetic and take insulin, you might be concerned about recent reports linking insulin use with cancer. However, you should know that such reports contain limitations. No existing study has proven whether the intake of insulin, or insulin analogs, reduces increases or has no effect on cancer risk.

Diabetes alone is a risk factor for cancer, so it is difficult isolate insulin as cancer's cause. However, in patients with insulin resistance, taking the hormone can feed pre-existing cancerous cells. Insulin lowers glucose levels in blood by binding to receptors on the cell membrane, which are abundant on cancer cells, promoting tumor growth. However, no evidence shows that insulin use causes the establishment of new cancer cells. Literature also suggests that insulin can actually lower cancer risk, because when it decreases glucose levels, cell glycolysis cannot occur. Cancer cells depend on the glycolytic pathway to generate energy (ATP) and cell reproduction materials (amino acids, nucleotides, and lipids). With insulin, there is less glucose and less hospitable conditions for cancer cells.

There is literature claiming insulin both heightens and reduces the risk of incident cancer. Furthermore, some studies even show no conclusive relationship. Multiple factors, such as dysglycemia, obesity, and insulin intolerance, might promote cancer growth. Thus, we cannot accept any hypothesis that insists on a unidirectional relationship between insulin use and cancer risk.

Reference: JAMA.2010; 303: 446-447.

Questioning the Benefits of Vertebroplasty

Yang (Karen) Chen

Vertebroplasty, a minimally-invasive procedure that prevents spine repair patients from depending on intravenous narcotics and bed rest, has previously been thought to have largely beneficial effects. However, two recently published, randomized control studies published in the New England Journal of Medicine (NEJM) report evidence against these preconceptions and have brought on a heated debate among physicians. The studies found that vertebroplasty for osteoporotic vertebral compression fractures did not yield significantly better results in terms of disability or short-term pain relief than sham procedures. Many physicians, particularly radiologists, are skeptical about the new findings. One of the radiologists' main concerns is that insurance companies will use the trials to justify ending coverage of vertebroplasy for osteoporotic spinal fractures. Their reactions are not surprising, as radiologists are vested in this procedure and make a living performing them. Spine physicians including Drs. J. Kevin McGraw and Christopher Bono insist that the studies are too flawed to serve as the evidence base for clinical practice. Critics like them argue that the two studies had too few patients, failed to meet enrollment, and included patients with milder degrees of pain and disability than those usually treated. Although the NEJM studies have an effect in promoting more research by increasing the level of uncertainty about vertebroplasty, it is doubtful that they alone will make any formal changes.

Reference: Gever, John . (2010, February 4). Fractured Evidence: Spine Repair Debate Heats Up. MedPage Today. Retrieved February 7, 2010 from http://www.medpagetoday.com/Surgery/Orthopedics/18303.

Reevaluating the Mental State of ‘Vegetative' Patients

Soumil Mhaskar

States of persistent unconsciousness have always been a mystery for the medical community. However, new findings at a clinic in Liège, Belgium may shed some light on this medical enigma. One of the clinic's patients has showed traces of brain activity in response to questions by doctors. The ‘vegetative' patient was able to show thought traces that indicated "yes" or "no" answers. This startling discovery may have broad implications and could possibly raise several ethical issues.

Scientific experts have swiftly responded to this report. The New England Journal of medicine posted online that they believe this finding does not suggest that unresponsive patients will get better and be able to communicate. Moreover, they believe that this ability to respond to doctor's commands is rare within ‘vegetative patients.' Furthermore, this does not apply to oxygen-deprived patients, such as Terri Schiavo, who was the center of the highly publicized battle over patients' rights.

This is not to say that this finding is not important. Many experts believe that this has exposed the current flaws in diagnosing the mental states of patients. As stated by Dr. James L. Bernat, a professor of neurology at Dartmouth Medical School, "I'm convinced as an observer that in these few cases, the M.R.I. technique, in these researchers' hands, gives us a window into human consciousness that we have not had and that potentially adds to the clinical exam we currently use."

This discovery corroborates recent research where ‘vegetative' patients showed increased brain activity in the corresponding regions of the brain when asked to think about motor movement and spatial recognition. Adrian M. Owen, a neuroscientist at the Medical Research Council in Cambridge, England, who co-authored the paper, said that the patient was able to respond "yes" or "no" to biographical questions. This ability to answer polar questions such as these raises the possibility of asking the patient whether he or she wants to live. Experts are not sure what the long-term consequences of this might be, but some are saying that a simple "yes" or "no" is not sufficient. Thus, further research is needed on this matter before concrete conclusions can be reached.

Reference: Carey, Benedict. (2010, February 3). Trace of Thought Is Found in ‘Vegetative' Patient. The New York Times. Retrieved February 7, 2010 from http://www.nytimes.com/2010/02/04/health/04brain.html?ref=health.

Post-Polio Syndrome: The Irony Afflicting Survivors

Lori Fingerhut

With the introduction of the polio vaccine in the 1950s, the polio virus no longer presents a threat to the health and welfare of Americans. However, for those who fell victim to the disease's crippling effects the memory is still alive and well. A year ago, Becky Lloyd, a researcher at the University of Utah's American West Center, took on the challenge of compiling an oral history of those who suffered from polio. What she found is that polio still affects these individuals physically thirty to more than fifty years after most had the disease. After suffering polio, the body's muscles and nerves are forced to compensate for the breakdown that occurred while the virus was active. Known as post-polio syndrome, the bodies of polio survivors are wearing out more quickly than those who did not suffer from polio as a child. In an unfortunate irony, those who worked the hardest to hide their polio and look normal are those who have shown the more dramatic cases of post-polio syndrome.

With the passing of time has also come the passing of many polio survivors. Money for post-polio research, and doctors who have experienced polio themselves, are becoming less and less. Remembering their experiences, such as through the Utah project, has allowed many polio survivors to find inner strength and to accept the effects of post-polio syndrome.

Reference: Johnson, Kirk. (2010, February 2). For Some Survivors, Polio Won't Fade Into the Past. The New York Times. Retrieved February 7, 2010 from http://www.nytimes.com/2010/02/03/health/03polio.html?ref=health.

Studies Report Conflicting Results in Reducing Dietary Sodium

Virginia Saurman

Michael H. Alderman, MD argues that recommendations on reduced daily sodium intake ought to be reevaluated before being pursued with vigor. While those in favor of its reduction point to clear evidence of lowered blood pressure, which can prevent stroke and heart attacks.

However, Randomized Clinical Trials with morbidity and mortality due to heart failure are the only such tests available to analyze the effects of different sodium intakes. Restricted sodium intake of 1840 mg /day significantly increased mortality and hospitalization compared with those with 2760 mg/day. The US average is 2921 mg/day. However, since the study dealt only with heart failure patients, the data is irrelevant for public health purposes.

At least thirteen observational studies have yielded conflicting results. Additionally, given the different populations, diets, and data collection methods and conflicting results, there are multiple hypotheses available. Further observational studies and debate are unlikely to clarify the issue any further. However, the real issue is the limitations of observational studies for dietary questions such as sodium intake and observational studies have no way of determining the effects of a change in diet; what is needed is a randomized clinical trial.

Given the current dilemma, there are two ways of dealing with the recommendation for sodium reduction: cut all sodium levels in prepared foods, or large-scale, rigorous, population-based, clinical trials. Advocates of sodium reduction in prepared foods argue that despite the heterogeneity of blood pressure response to lowered sodium, the benefits outweigh the risks. The clinical trial route would take longer and require thousands of patients, but results in more precision and scientific credibility to help answer the question of sodium levels. Additionally, the human and material risks would be vastly smaller than an across the board sodium reduction. Both methods are experimental given the lack of definitive evidence. Regardless of the route taken, caution is a necessity.

Reference: JAMA.2010; 303: 448-449.

Eriene-Heidi Sidhom is the 2009 - 2010 News and Analysis Editor.

The Role of Mental Health Professionals in Torture

Hoai Le

An investigation by Derrick Silvone and Susan Rees of the University of New South Wales reports that mental health professionals should not be expected to partake in the torture of detainees. US military personnel have long argued that a psychologist's presence is necessary during interrogations to prevent the risk of abuse and harm. However, associations of psychologists and psychiatrists all agree that mental health professionals should not participate in the interrogation process of detainees or any activities that may lead to torture. Besides the obvious ethical problems involved, there is no scientific evidence to support the claim that psychologists have the ability to accurately assess the level of pain that an individual is experiencing. In addition, it is even more difficult to judge the long term psychological consequences of torture because some individuals show delayed symptoms. The report concludes that if US military personnel were really concerned with the safety of detainees, they are better off consulting a human rights expert than a mental health professional.

Reference: BMJ 2010;340:c124

The Cost of Autism on Families

Eriene-Heidi Sidhom

Autism is a growing problem in the United States; in 2007 it was reported that one in every 150 children were diagnosed with autism and since then that number has risen to one in every 110 children. Although treatments and therapies for autism are publicized, the prices associated with them are rarely spoken about. Unfortunately, the doctor visits, prescriptions, therapy and special education can cost a family $67,000 to $72,000 per year and $3.2 million over a lifetime. With limited or no coverage from insurance companies and very little government or financial assistance, this cost is not being addressed properly and has become a financial burden for many families.

However, improvement is being made and there is help being made available. Some large employers have policies to cover treatment and fifteen states have passed laws mandating some autism-related coverage. Additionally, some states offer Medicaid coverage for children with autism; although this is usually reserved for more serious cases and the waiting list for a Medicaid waiver can be long. Autism advocacy groups, such as Autism Speaks, are affiliated with local chapters that provide autism resources and support groups and organizations, like the National Autism Association, can offer financial help. Organizations like these and continuing financial aid is becoming increasingly mandatory because of the increasing cases of autism; in fact, Pat Kemp, executive vice president of the advocacy group Autism Speaks, predicts that "Unless we attack this like a national health crisis, we're going to have a huge economic crisis on our hands."

Reference: Konrad, Walecia. (2010, January 23). Dealing With the Financial Burden of Autism. The New York Times, p. B6.

The Fifth Phase of Epidemiologic Transition: Obesity

Adam Snider

Phases of epidemiologic transition have been categorized based on the most prevalent causes of death in a population. The first phase was characterized by death due to pestilence and famine. As cities became cleaner, and food production became more efficient, a second phase arose, defined by infectious disease. This phase was then replaced by one identified by degenerative and human-made health concerns such as smoking, fat-laden diets, and cardiovascular disease. Many of these problems were combated by advances in both preventative care and treatment, such as anti-smoking programs, and drugs to control blood pressure. Since 1960, we have entered a fifth wave: the age of obesity and inactivity. The percentage of adults considered obese (BMI>30) has risen over the past 50 years, bringing with it a host of associated health risks, including coronary heart disease, type 2 diabetes, joint disease, cancer and others. These trends have been reflected in today's youth: 17% of school age children are obese, facing similar long-term healthcare prospects as light smokers. Unlike smoking, there is no clear consensus on how to treat this growing epidemic. Pharmacology and bariatric surgery hold short-term promise, but have yet to be proven in a longer-term setting. The promotion of healthy lifestyles has yielded poor results. Currently, experts believe the best treatment is a combination of all three. Effective treatment is of dire need, as obesity-related healthcare costs currently pose a $147 billion burden on the system.

Reference: JAMA. 2010;303(3):275-276

The Pros and Cons of Simulated Patients

Namratha Rao

Trial and error used to be the most common practice among young doctors to practice team coordination and efficiency in medical cases. However, there has been an increase in medical simulation training in many organizations; previously only used to teach standard techniques, like chest compressions, the technology has expanded to recreate an entire clinical situation, even including the difficult conversations with family members. Apart from providing experience, without the stress of real patients, simulations enhance team-work and decision-making skills. However, this is also a criticism of medical simulations because some claim that actual medical practice on patients is very different. Additional criticisms include the difficulty to assess the success of simulation training and the high costs with no guarantee of a return.

Organizations currently employing medical simulation training include Stanford University School of Medicine, Banner Health, a non-profit system and New York City Health and Hospitals Corporation Institute.

Reference: Chen, Pauline W., M.D. (2010, January 28). Practicing on Patients, Real and Otherwise. The New York Times. Retrieved February 1, 2010 from http://www.nytimes.com/2010/01/29/health/28chen.html.

Keeping those New Year's Resolutions

Kanupriya Tewari

Make New Year's resolutions you can't keep? There may be a scientifically proven reason as to why. Advances in neuroimaging have enabled researchers to peer inside the brains of addicts and patients with addictive behaviors. They can see in real-time what gets patients addicted: how the brain's reward system - based largely on the neurotransmitter dopamine - asks for more, while inhibitory control centers experience a system failure. The pattern is similar across all kinds of behaviors; from cocaine and tobacco addiction to overeating. Therefore, changing the mind may be the first step toward breaking a habit, but altering the brain's neural machinery is the real challenge

Petros Levounis, MD, director of the Addiction Institute of New York at St. Luke's and Roosevelt Hospitals in Manhattan says that "Drug-taking and other addictive behaviors ‘hijack' the brain's reward system". He further emphasizes "Imagine what a strong hold these hijacked reward pathways take on our brains and our whole existence when they're so closely connected, geographically and anatomically speaking, with our memories and our emotions".

These neural pathways have been well studied in the brains of hardcore addicts. Now, researchers say they see similar pathways involved in other bad behaviors. Researchers have identified two means through which to fix this problem. Basically, the idea of medications that act on the dopamine system is "to cool down those reward pathways," Levounis says. There are two strategies for doing so: an agonist strategy, or an antagonist strategy. The agonist strategy is "feeding the beast, providing activity in the cell so that the cravings go down," Levounis said. Classic examples are nicotine patches, or methadone for opioid dependence. On the other hand, the antagonist strategy is to block the receptors. Naltrexone, for example, will block opioid receptors so that the drug addict won't feel anything if they attempt to get high.

Reference: Fiore, Kristina. (2010, January 30). Doctor's Orders: Brain's Wiring Makes Change Hard. MedPage Today. Retrieved February 1, 2010 from http://www.medpagetoday.com/Psychiatry/Addictions/18207.

Eriene-Heidi Sidhom is the 2009 - 2010 News and Analysis Editor.

Reduction of Funding for Massachusetts Disease Prevention Programs

Jeremy Nowak

Due to drastic Massachusetts state budget cuts, the state Department of Health will lose approximately $32 million, or about 9% of its non-hospital budget. Among the programs losing money are the smoking cessation effort (its funds will be cut by about 10%), teen pregnancy, youth violence, and suicide. The Center for Primary Care Recruitment, a program which helps pay for doctors' medical school debts if they work for community health centers, will lose all of its state funding. The reductions will officially be released by Massachusetts state governor Deval Patrick in the next few days.

New Replacement Valves Could be the Latest Advancement in Cardiology

Jeremy Nowak

Companies Edwards Lifesciences and Medtronic are racing against each other to see who will first put the newest advancement in cardiology on the market. Both companies are designing new replacement valves which have the potential to repair the heart without open-chest surgery. The valves can be implanted directly into the heart via thin tubes known as catheters. These catheters can be inserted via an incision near the groin or the ribs and they release the valve near the heart, compressing the dead tissue and extending the lives of patients who are too weak to receive open heart surgery. While not yet available in the United States, these new valves have been present in Europe for about 18 months and have had sales of about $100 million. If approved by the FDA, these new valves could be placed on the market within the next two years.

If these replacement valves are put on the market, there would most likely be a huge drop in valve-related disease deaths (currently about 20,000 people a year die from these diseases). However, this technology would be very expensive for the average patient. A current replacement valve costs about $5,000 and these new valves in Europe sell for about $30,000. Another issue is what circumstances these new valves should be used in. The success rate of open-heart surgery is very high and the valves used in the surgery typically last from 10 to 15 years. The lifespan of the newer valve is not yet known.

A New Antipsychotic on the Market

Marina Bartzokis

After 13 years of developing the drug Fanapt, Vanda Pharmaceuticals is looking forward to having the antipsychotic finally be put on the market. Fanapt functions as an antipsychotic by blocking neurotransmitter signals involved in the parts of the brain active in schizophrenics. What makes it different is that it targets neurotransmitters that are more "relevant," and thus posses less side effects than other similar drugs on the market. It was initially developed by Titan Pharmaceuticals and was then bought by the pharmaceutical giant, Novartis. After the FDA gave the drug a negative ruling last year, however, investors and Novartis jumped ship. Novartis sold the drug to the former head of their pharmacogenetics unit, Mihael Polymeropoulos, who was in the process of starting up his own pharmaceutical company, Vanda Pharmaceuticals (the name under which Fanapt will currently be marketed). Since then, studies regarding Fanapt have been more positive. Novartis has since bought back the product to assist in its release into the market. As a result of the transfer of rights to the drug, however, Titan will receive royalties and Novartis will also collect a portion of the profits.

Value of Exercise May Not Be What It Appears

Kristin Bradley

Recent studies have indicated that the benefits of exercise may not be as widespread as believed in the past. Exercising has been shown to decrease the risk of developing both diabetes and heart disease, but the correlation between exercise and protection against heart disease is strongest in people who previously did not exercise regularly. The link between exercise and health was studied with respect to heart disease and certain types of cancers, but it is difficult to assess because active people tend to be well-educated and lead healthier lifestyles, which could cause their protection against disease or be an effect of that protection. Exercise has been shown to prevent the effects of osteoporosis, but this is not through the prevention of the disease itself but rather through the development of coordination that prevents falls and the resulting broken bones. There is no direct link between weight loss and exercise alone; although exercise leads to an increase in muscle mass, there is no corresponding increase in metabolic rate. Blood pressure and cholesterol levels have also shown no correlation with exercise in the absence of weight loss, and many scientists, including researchers at the University of South Carolina, believe that a combination of diet and exercise is the best way to lose weight and reduce blood pressure and cholesterol.

Evolution Still Occurs in Humans

Kristin Bradley

The Framingham Heart Study, a research study spanning over six decades and thousands of participants living in the Boston suburbs, has collected evidence that indicates that humans are still evolving. Evolution occurs through natural selection, in which differences between organisms within a certain species cause certain individuals to be more fit and survive to produce the most fertile offspring. According to Stephen C. Stearns, a biology professor at Yale, many people believe that humans are no longer evolving due to advances in medical technology. The heart study indicates that human evolution is still occurring but at a rate much slower than the finches studied by Charles Darwin, the originator of the theory of natural selection. Analysis of the data on the traits of women and the number of children they had predicts that in the next generation, women will be slightly heavier and shorter with lower cholesterol, a lower age at first childbearing, and a higher age at menopause. These predictions have raised new questions as the researchers look to investigate how much the environment influences the traits and why these traits bestow evolutionary fitness.

Cancer Today, Healed Tomorrow

Lauren-Elizabeth Palmer

Can cancer just disappear? You would probably say no, but a paper recently released in The Journal of the American Medical Association suggests that, yes, some cancers are shrinking or even disappearing on their own. The cancers surrounding this issue are mostly those that have to do with the endocrine system; that is cancers of the breast, cervix, prostate and testes. It seems that, with these cancers, doctors are seeing tumors shrink and even completely vanish on their own. The article suggests two plausible explanations for this fact. It is important to note that we have extensive screening processes for these specific cancers. Men and women are tested for these cancers very early and frequently. With such detailed screening processes, there are bound to be false positives or the identification of benign tumors. It seems that, in our hunt to eradicate ourselves of cancer, we are finding tumors which are not really problems and may go away on their own.

There is a second explanation, however, which seems counterintuitive. It may be that, in some cases, our cancers are just disappearing. For a few decades it seems, doctors have been observing the spontaneous self-healing of testicular cancers. It seems that tumors in the testes show up and the simply go away without treatment leaving only a scar. This same sort of vanishing act is employed by kidney tumors as well. This issue has caught the attention of enough researchers that a countrywide study is currently underway which measures the progression of patients with kidney tumors.