Chance Cancer Mutations

This new year, researchers concluded that 2/3 of the difference in cancer risk between different parts of the body can be attributed to the number of stem cell divisions those parts undergo. More cell divisions reflect a higher risk as errors that occur naturally during the DNA replication process can contribute to the development of cancer. In other words, the same genetic mutability that enables evolution also ensures that many people will be afflicted by a terrible disease. On Pharyngula, PZ Myers suggests this is one reason our cells naturally get old and stop dividing: because if they continued forever, too many mutations would accumulate in the individual.

Of course, mutations are rare and unpredictably distributed, and not all of them are dangerous, making who gets cancer largely a matter of chance. The new study shows which cancers are most influenced by lifestyle factors such as using tobacco. PZ writes,”colorectal and lung cancers do have a significant risk beyond what can be accounted for by stochastic errors, so pursuing a reduction in exposure to risk factors, like diet and smoking, can have a useful role in reducing the incidence of these cancers.” On the flip side, the incidence of pancreatic cancer (for example) can be totally accounted for by random mutation.


Supernova Flashes and Silver Linings

New research from the Weizmann Institute of Science reveals that “cells in our brain form little hexagonal grids that keep us oriented, map-like, in our surroundings.” Weizmann’s resident blogger describes this finding as “a pyrotechnic flash of insight that changes how we understand the brain to work.” Game developers delight; this discovery shows “that you can really apply mathematical models to understand how our mammalian brains get their bearings.” It may also have immediate implications for understanding human brain disorders such as vertigo. Meanwhile, on ERV, Abbie Smith explores a silver lining emerging from ongoing research into the viral scourge known as HIV. Abbie explains that HIV viruses genetically reprogrammed by scientists to “modify relapsed acute lymphoblastic leukemia (ALL) patients T-cells” are prolonging and possibly saving the lives of kids. Continued genetic modification could transform HIV into a powerful tool for fighting cancer and other diseases. Finally, on The Pump Handle, Elizabeth Grossman writes that rapid job growth in oil and gas industry is shining a light on some of the most dangerous jobs on the planet. Elizabeth writes, “Last year, 112 oil and gas industry workers were killed on the job and about 9,000 suffered non-fatal, work-related injuries and illnesses.” Hazards include toxic chemicals, respirable silica, and radiation exposure, not to mention “motor vehicle crashes, fires, electrocution and explosions.” But a new alliance between OSHA, NIOSH, and the National STEPS Network promises to fight for better workplace safety for these very important employees. Oh and for those not satisfied with a metaphor: some real supernova goodness from Ethan Siegel.

Life, Death, and ERVs

In a phenomenon known as Peto’s paradox, large mammals do not develop cancer more often than small mammals, despite having more cells that could go haywire. On Life Lines, Dr. Dolittle writes “Some researchers suggested that perhaps smaller animals developed more oxidative stress as a result of having higher metabolisms. Others proposed that perhaps larger animals have more genes that suppress tumors.” But a new hypothesis argues that large mammals have evolved to minimize the activity of ERVs, which are ancient viral elements integrated into our DNA. Active ERVs can cause cancer and possibly other diseases; mice exhibit about 3300 active ERVs, while humans exhibit about 350. On the blog known as ERV, Abbie Smith writes “some of the young ERVs in humans, the ones that can still code for a protein here and there, are reactivated in HIV+ patients.” Researchers are considering targeting these ERVs in order to combat HIV; as Abbie writes, “You could train the HIV+ individuals immune system to ‘see’ the ERV components in an HIV infected CD4+ T-cell, and BAM! Kill the HIV infected cell!” But she warns that other ERV components are expressed in many normal human cells, and teaching our immune system to target them might be a very bad idea.

Making Cancer, and Making It Worse

On Pharyngula, PZ Myers says that cancer, unlike an infectious bacterium or virus, is not the product of millions of years of evolution. Instead, PZ writes, “Cancer misuses and perverts existing processes in your cells to send them out of control.” But what causes cancer? Well, it happens about 20,000 times a day in your body. Luckily, it is almost always repaired. It is the mutation of DNA during cell division. Just one base out of place, and suddenly the gene that made a protein to tightly regulate cell division is making a protein that encourages the cell to divide continually. Depending on what other mutations this cell line, by chance or carcinogen, accumulates, it can grow to destroy the body. PZ also explains the role of tumor suppressor genes, which generally stop uncontrolled cell division.  Sexual beings have two copies of every gene in their bodies, and for some cancers to be successful, both copies of a tumor suppressor gene must be knocked out.  On the other hand, new research at the Weizmann Institute suggests that for leukemia cells to proliferate, one copy of a cancer-causing gene must remain healthy even though the other must be mutated.  And on Respectful Insolence, Orac takes another look at the endless parade of cancer quackery in the media, in this case a talk-show host praising a doctor whose treatment regimen (including 150 pills per day and a coffee enema) appeared in a clinical trial to make pancreatic cancer patients die sooner.

Posted to the homepage on September 23, 2013.

Hey Kids, Some Drugs Are Good for You

The U.S. “war on drugs,” besides failing to meet its goals, has demonstrated a stubborn ignorance of the effects that different drugs have in the human body. Granted, some drugs cause degeneration and are properly outlawed. Opiates such as heroin and stimulants such as cocaine and methamphetamine take a harsh physical toll and leave users addicted to the chemical. But classified along with these truly dangerous drugs are some of nature’s most mysterious medicines. New research shows how marijuana, psychedelics, MDMA and even ketamine have positive physiological and psychological effects that can persist even after the drug has worn off.

The marijuana flower, of course, is the nearest of these drugs to public and political acceptance, and the transformation of its image over the decades is very instructive. Stuck with a Spanish name in the 1930’s to excite American xenophobia, marijuana has long been demonized as causing “reefer madness.” In fact, new research shows that marijuana has potent neuroprotective and neuroplastic properties, in addition to its power as a non-addictive painkiller.  Marijuana contains at least 85 cannabinoid chemicals, including the well-known THC, and the lesser known CBD.  New research shows that CBD, administered thirty minutes after a devastating loss of oxygen in mice brains, totally circumvented brain damage.  Cannabinoids are currently being studied for a wide range of therapeutic applications, including the fight against cancer.  Their potency should come as no surprise since all mammals have cannabinoid receptors in their brains.  According to Salon, these receptors evolved in animals 550 million years before the marijuana plant.

Psychedelic drugs are very different; the most popular ones are psilocybin, mescaline, and LSD.  Psilocybin and mescaline occur naturally, in certain mushrooms and cacti, respectively.  LSD must be made in a laboratory.  These drugs have differing effects, but the psychedelic experience has many features in common.  A new study in PLOS ONE showed no correlation between a lifetime of psychedelic use and negative mental health outcomes.  In fact, “in several cases psychedelic use was associated with lower rate of mental health problems.” Ongoing research on psilocybin suggests that it can help terminally ill patients come to terms with their mortality in healthy and beneficial ways.  Meanwhile mescaline, in the form of peyote, is exempt from DEA regulation when taken under certain religious circumstances.  Mescaline and psilocybin have been used in tribal cultures for thousands of years as tools for understanding the self and the world. If you try them just once your life can change drastically. After marijuana, magic mushrooms and peyote cactus should be decriminalized as natural, non-addictive, safe substances.  LSD on the other hand can cause psychedelic effects for up to 16 hours (about twice as long as psilocybin) and may present a bigger danger to public health.

Similar in effect to psychedelics, but also demonstrating stimulant properties, is MDMA or Ecstasy.  While conflicting research suggests that long term or heavy use of MDMA may cause brain damage, a 2011 study at UCLA “found that persons with autism using the drug often report an increase in socialization and strong feelings of empathy that last even after the drug has worn off.”  Perhaps one day this darling of dance culture will be available for therapeutic use by prescription.

Finally, there’s a drug you may not have heard of: Ketamine, best known as a horse tranquilizer and club drug.  In sub-anaesthetic doses “Special K” causes very strange psychological effects unlike those of pot or psychedelics.  It’s a type of drug known as a dissociative, along PCP and dextromethorphan.  But while these latter drugs can cause psychosis and brain damage, Ketamine turns out to be pretty gentle, and may even have a future as an antidepressant.  According to Scientific American, “the enthusiasm for ketamine is such that physicians, often working out of small clinics, have already started prescribing low doses of the generic anesthetic off-label […] and drug companies are contemplating whether to get into the act by creating new drugs based on ketamine’s biochemistry.”

A word of warning: these drugs are illegal for recreational use, they often have unpleasant effects, and it’s always possible to get too much of a good thing.  Many drugs are truly dangerous and deserve to remain tightly regulated or illegal.  One needs only to read about the emergence of krokodil, a street form of mesomorphine cooked up from codeine and toxic chemicals, to be reminded of the horrors of drug addiction.

But the prohibition of safe, non-addictive, psychologically inspiring, and medically promising substances is not the answer.

Genital Warts Will Be History

On ERV, Abbie Smith reports on the phenomenal success of the HPV vaccine in Australia.  The vaccine, designed to protect against several types of sexually-transmitted papillomavirus, was first administered to Aussie girls in 2007.  Since then, total prevalence of the virus among young women has dropped from 11.5% to less than 1%—and to 0% among girls who actually got the vaccine.  These girls are also protecting their partners and reducing overall circulation of HPV; infections among young men, who were not even vaccinated, dropped from 12.1 to 2.2 percent. Abbie calls this a “blatant, obvious example of herd immunity in action!”  On Aardvarchaeology, Martin Rundkvist recently stood up for science against the false equivalence of “tell both sides” journalism in Sweden, where the HPV vaccine is offered to all twelve year old girls.  Martin acknowledges the vaccine is not 100% effective, and there are very rare cases of adverse side-effects, but the same is true of any vaccine.