Tag: disease

Gene Editing Fixes Harmful Mutation In Human Embryos

GENE

Scientists have successfully edited the DNA of human embryos to erase a heritable heart condition that is known for causing sudden death in young competitive athletes, cracking open the doors to a controversial new era in medicine.

This is the first time gene editing on human embryos has been conducted in the United States. Researchers said in interviews this week that they consider their work very basic.




The embryos were allowed to grow for only a few days, and there was never any intention to implant them to create a pregnancy.

But they also acknowledged that they will continue to move forward with the science, with the ultimate goal of being able to “correct” disease-causing genes in embryos that will develop into babies.

News of the remarkable experiment began to circulate last week, but details became public Wednesday with a paper in the journal Nature.

The experiment is the latest example of how the laboratory tool known as CRISPR (or Clustered Regularly Interspaced Short Palindromic Repeats), a type of “molecular scissors,” is pushing the boundaries of our ability to manipulate life, and it has been received with both excitement and horror.

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Pass it on: Popular Science

Contagious Cancer Drives the Risk of Extinction Of Tasmanian Devils

Twenty years ago, scientists identified a bizarre new disease afflicting Australia’s Tasmanian devils. These black, rambunctious, corgi-sized predators started turning up with grotesque facial tumors that proved invariably fatal.

The disease, aptly named devil facial tumor disease (DFTD), quickly spread through the devils’ island home of Tasmania, slashing their numbers by up to 90 percent in some regions, and consigning them to the endangered-species list in 2008.

After a decade, scientists realized that all cases of DFTD are genetically identical. The tumors were all clones of each other, and distinct from the devils that harbor them.

The conclusion was clear and astonishing—DFTD is a contagious cancer, and the devils were catching it from each other.

Cancers are almost always confined to a single body: when their host dies, so do they. But in the Tasmanian devils, one particular tumor had evolved the ability to jump from host to host.

The boisterous devils spread this transmissible tumor when they squabble over carcasses and bite each other in the face.




Contagious cancers don’t exist in humans; we can develop cancer after contracting infections like the HPV virus or the bacterium Helicobacter pylori, but the tumors themselves can’t spread between people.

In fact, DFTD is one of only three known wild transmissible tumors.

There’s also CTVT, a venereal tumor of dogs, which arose around 11,000 years ago, and has since conquered the world by hitchhiking on the genitals of domestic pooches.

And there’s a water-borne leukemia that’s spreading through North America’s soft-shell clams. That’s it.

They’re flukes of nature,” says Elizabeth Murchison from the University of Cambridge, who has studied DFTD for years. Our whole paradigm about transmissible cancers is that they’re extraordinarily rare.

Or are they?

In March 2014, Murchison’s colleague Ruth Pye, a graduate student at the University of Tasmania, noticed something weird about a facial tumor taken from a devil captured just north of Hobart.

Physically, it looked like DFTD; genetically, it was clearly something different. For example, DFTD cells have lost their X and Y sex chromosomes, both of which were present in the new tumor.

Pye reasoned that this particular devil had spontaneously developed its own type of facial tumor that looked like DFTD, but wasn’t. It was a one-off.

Except, a few months later, she found the same genetically distinct tumor in a second devil from the same area.

In both cases, the tumors bore absolutely no genetic resemblance to either DFTD or their respective hosts. These devils had developed a second type of contagious cancer.

We absolutely couldn’t believe it,” says Murchison. “It’s the last thing I could have possibly imagined.”

It could be that the devils are extraordinarily susceptible to these kinds of cancers.

A historical population crash left them with very low genetic diversity, which perhaps stops their immune systems from recognizing the foreign cancer cells and fighting them off.

They also bite each other on the face a lot, which provides an easy route of transmission.

But that doesn’t explain why DFT1 and DFT2 didn’t exist before the 1990s. It’s unlikely that scientists simply didn’t notice; as Murchison says, you can’t miss tumors that are that obvious.

Maybe something is triggering them, some kind of predisposing agent or infection,” says Murchison. “We really don’t understand it.

There’s one silver lining: DFT2 could help scientists to better understand DFT1, its more common and problematic cousin. “Any mutations that are common to both of them are probably going to be important,” says Murchison.

I’m hoping it’s a chance to learn more about transmissible cancers in devils and do something to help save them.

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Pass it on: Popular Science

Superbugs And Antibiotic Resistance

For the last century, medical professionals and microbiologists have waged a war against germs of every type and with the breakthrough of antibiotics, changed the world in which we live.

It also changed the world for our symbionts, the 4 to 6 pounds of bacteria, fungi and viruses who have hung on to our species through thick and thin for eons of time; to them we are their movable feast.

It was indeed a war that we appeared to be winning.  We thought we were firmly living in the ‘Antibiotic-Age’ and it was here to stay for all time.

However, while we were basking in its potency, unfortunately we were also rapidly and inexplicably sowing the seeds of its demise.

In a recent landmark report, US health policy makers warn that, with mounting evidence of superbugs overcoming our antibiotics,  that our situation is extremely serious.

The report gives a glimpse of the world to come, as even now there are a dozen different drug resistant microbial species that have totally overcome our existing antibiotics.

These resistant strains are now responsible for causing 2 million infections and 23,000 deaths each year in the US alone.




According to the WHO, the rapid emergence of multi-drug resistant (MDR) strains calls for a comprehensive and coordinated response to prevent a global catastrophe.

The WHO warns that, “...many infectious diseases are rapidly becoming untreatable and uncontrollable.”

CDC director Tom Frieden says that we must take urgent action to “change the way antibiotics are used” by cutting unneeded use in humans and animals and take basic steps to prevent infections in the first place.

The tools we have at our disposal, besides tracking resistant infections, are vaccines, safe food & patient infection control practices, paired with effective and enlightened hand hygiene.

Human populations weathered numerous plagues before antibiotics were discovered. It is edifying that geneticists have found that the human genome is littered with the remnants of our past battles with pathogens.

The difference is that today we know how to effectively apply all of the preventive measures that are at our disposal.

We should keep in mind that the advent of infectious disease adapted to humans is a relatively recent phenomenon.

The ‘Post-Antibiotic Age’, if it comes, represents the ongoing evolution between a microbe and its human host, with hand & surface hygiene reigning supreme as the most effective means of preventing infection.

These elements, along with water sanitation and hygienic treatment of human waste, have formed the basis for the hygiene revolution over the last hundred years.

Within this, the discovery and development of antibiotics is perhaps the short lived apex or crowning glory of the revolution.

To rise to the challenge, we need to recognize that our bodies are complex ecological systems and the maintenance of our barrier function is critical to preventing skin infection and keeping out invading pathogens.

This is no more than an extension and further development of the original hygiene revolution, where we see the true relations between living organisms and the many elements of the environment.

Skin health is critical to maintaining hand hygiene compliance.  Hand hygiene is certainly capable of rising to the challenge, but not if skin is damaged.

In the ‘Post-Antibiotic Age’, maintaining healthy skin will be essential to preventing a wide range of infections caused by strains we helped to create.

Healthy hands are safe hands, but hand hygiene does not have to go it alone if there is a “sea-change” with respect to how agri-food producers and healthcare professionals utilize antibiotics.

CDC Director Frieden stated that, “It’s not too late,” but that there is a list of urgent and life-threatening infections that must be addressed via a more effective collaboration; they include carbapenem-resistant Enterobacteriaceae (CRE), drug resistant gonorrhea and C. difficile.

The WHO has called for the agri-food industry to take the threat of MDRs seriously and curb over use of antibiotics, particularly as it is estimated that there is at least a 1000-fold greater use of antibiotics compared to humans.

In hospitals we must embrace best antibiotic and hygiene practices to make a turn from what the Center for Global Development has called “a decade of neglect“.

We need to “Get  Smart” and set targets for reducing antibiotic use in healthcare facilities.

Let’s all appreciate the good microbial flora and fauna that exist on and in us, as without these little creatures life as we know it would not exist.

We should also recognize that the more bad bugs encounter antibiotics, the more likely they are to adapt. As Health Canada puts it, “Do bugs need drugs?“.

While antibiotics have allowed us to temporarily gain the upper hand, nothing lasts forever;  but with a holistic view of hand hygiene there is no reason why we can’t continue to improve our control of infections.

But for this to happen, there can be no excuses or compromises for effective hand hygiene practices.

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Pass it on: New Scientist

 

Do You Always Check The Weather Before Going Out? You Should Check The Disease Map Too.

The field of medical geographic information systems (Medical GIS) has become extremely useful in understanding the bigger picture of public health.

The discipline holds a substantial capacity to understand not only differences, but also similarities in population health all over the world.

New diseases and epidemics spread through the world’s population every year.




The discipline of medical geographic information systems (GIS) provides a strong framework for our increasing ability to monitor these diseases and identify their causes.

The field of medical geography has a much longer history than most are aware of, dating back to the first known doctor, Hippocrates, and progressing through the 1900s until today.

The early history leads us to the examination of contemporary examples of GIS, influences on public health, space-time mapping components, and the future of this discipline supported by Big Data.

The evolution of medical GIS from early disease maps to digital maps is a journey long in the making, and continues to evolve.

These maps have enabled us to gain insight about diseases ranging from cholera to cancer, all while increasing the knowledge of worldwide health issues.

As modern technology continues to thrive, medical GIS will remain a lasting approach for understanding populations and the world we live in.

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Pass it on: New Scientist