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Archive for the ‘Health’ Category

DNA adducts--as strings of DNA damaged by carcinogens are known--serve as biomarkers for doctors, letting them know what diseases a patient might be vulnerable to and helping them monitor for ailments that the patient has a higher likelihood of developing. They’re kind of like a direct measurement of what carcinogens a person is coming in contact with in his or her daily life, through conscious choices or things like a job environment, and how those things are affecting that person’s genetic material.

Our DNA has mechanisms for repairing itself when carcinogens damage our genetic material, but when it fails to do so that genetic damage can lead to cell mutations and eventually to health problems like cancer and inflammatory diseases. So being conscious of what lifestyle choices and other factors are impacting our DNA can be extremely important.

It’s also relatively science intensive, and therefore not so common (do you have any idea what carcinogens are riding on your DNA? I could make a guess, but have no idea for certain). The saliva test developed by a research team at National Chung Cheng University (NCCU) in Taiwan makes keeping track of common DNA adducts much easier. From a saliva sample it can extract white blood cells found naturally there and then use mass spectrometry to analyze for specific DNA adducts.

The test would likely cost several hundred dollars--a cost that, in terms of potential preventative benefits, might be well worth it. And it's a first step toward what might eventually become a kind of cancer screening carried out by saliva swab. In the meantime, the researchers hope the tool might be used to help influence patients’ lifestyle choice. For instance, smokers could be shown exactly how their habit is damaging their DNA via high counts of DNA adducts. Future tests could then show, in plain terms, how curbing a behavior like smoking can have a direct impact on one’s genetic health.

[Science Daily]

Our microbiomes are the collection of bacterial microbes that we carry around with us all the time, those symbiotic little bugs that live on our skin and in our esophagi and--very importantly--in our guts. And while we’ve long known that a cycle of antibiotics prescribed to kill off an infection can also kill off some of our most important beneficial microorganisms, the general line of thinking is that once the cycle of antibiotics ends our microbiomes correct themselves and the natural order of things returns.

Blaser presents arguments otherwise in an editorial that suggests that our gut bacteria is permanently affected by a cycle of antibiotics, and that the impact is so profound that it might be time to seriously consider not giving antibiotics to anyone other than very young children and pregnant women. Quoted by Maryn McKenna in Wired:

Early evidence from my lab and others hints that, sometimes, our friendly flora never fully recover. These long-term changes to the beneficial bacteria within people’s bodies may even increase our susceptibility to infections and disease. Overuse of antibiotics could be fueling the dramatic increase in conditions such as obesity, type 1 diabetes, inflammatory bowel disease, allergies and asthma, which have more than doubled in many populations.

He then goes on to present some disconcerting correlations between the absence of certain bacteria and the rise in incidences of things like allergy, asthma, and weight gain. He points to evidence that children are getting too many doses of antibiotics before adulthood and that their microbiomes are never the same for it--specifically that the damage to our gut bacteria populations is permanent from that point forward.

Which leads to an eventual conclusion that when our children are sick we shouldn’t give them what we know will make them better. And that’s a tough pill to swallow.

[Wired]

In principle, the circuit works like any other logic circuit: It analyzes multiple inputs and makes a decision. In this case, the circuit really consists of genes that can detect up to five cancer-specific molecules and their concentrations. When all five of those characteristics are present, the circuit makes a positive determination, and then it triggers cell death.

In a new study, researchers from MIT and ETH Zurich worked with HeLa cells, a prolific type of cervical cancer cell. They studied the cells’ microRNA, which regulates gene expression by destroying messenger RNA, the substance that brings the DNA blueprint to the rest of the cell. They eventually pinpointed one microRNA combo that was unique to HeLa cells. This is no small feat by itself — there are about 1,000 versions of miRNA in humans, according to MIT News. Each type of cancer has a unique miRNA profile.

Once they had the right combination, the researchers designed a synthetic gene which codes for a protein that promotes apoptosis, or programmed cell death. The special gene would turn on in the presence of miRNA levels that match the HeLa profile.

“The biocomputer combines the factors using logic operations such as AND and NOT, and only generates the required outcome, namely cell death, when the entire calculation with all the factors results in a logical TRUE value,” Yaakov Benenson, a professor of synthetic biology at ETH Zurich, said in a statement.

If the miRNA levels were too high or too low, the gene would not switch on, and the cell would not be killed. Healthy cells, which would also lack the HeLa profile, would be similarly left alone, the researchers said.

The next step would be to test this system in a living animal, but this will be difficult. Current methods use viruses or chemicals to bring foreign DNA inside cells, but these make permanent changes, which could have their own complications. So the method is still far from being usable for cancer treatment, researchers said.

Still, it is an important step toward building a single-cell-level diagnostic method, Benenson said. The research was published in today’s issue of Science.

[Eurekalert]

The microscope has two ways of analyzing samples: a transmission mode and a reflection mode. The transmission mode is good for transparent media, like thin slices of a sample or clear liquids. In this case, the microscope’s laser can easily penetrate and analyze microscopic objects. For denser, more solid samples the microscope uses holography to generate a 3-D image of the sample that can be beamed to remote computers for further analysis if necessary.

In reflection mode, the microscope basically splits the laser beam using a mirror. It then uses one half of the beam to illuminate the sample. On the other side the sample beam and the control beam are recombined. Some “clever mathematics” can then use resulting the changes in the beam to generate a 3-D image of the object sampled.

But while that may sound fairly high-tech, there are no expensive optics or other pricey components required. The photo sensors are of the variety often found in smartphones, and small lasers like the one used in the device are really inexpensive these days as well. That all means that these holographic microscopes could be widely deployed at little cost.

And that’s the idea. Places that don’t have access to high-tech diagnostic equipment could use these devices to sample food and water--or even human blood--for harmful bugs and beam the images to more powerful computing devices elsewhere for analysis or diagnosis. That could help contain contaminations and outbreaks faster, saving lives while keeping costs down.

[BBC]

Scientists fed mice a broth containing Lactobacillus rhamnosus, a strain of Lactobacillus species that is found in mouse gastrointestinal systems, and watched the mice’s behavior. They appeared less stressed and depressed than mice who got a plain broth, the researchers reported. When they were placed in water to deliberately stress them out, the L. rhamnosus-fed mice also had lower levels of stress hormones.

John Cryan, a neuroscientist at University College Cork in Ireland, also monitored the animals’ brains to watch for changes. He and colleagues found heightened activity in one of the receptors for a neurotransmitter called GABA, which regulates psychological processes. Certain depression drugs target GABA receptors, ScienceNow points out. Cryan and his colleagues found that certain portions of the neurotransmitter that are normally reduced during depression were more highly expressed in the L. rhamnosus mice. And other areas that are increased during depression were less pronounced in the L. rhamnosus mice.

To prove there really was a connection between the stomach bacteria and GABA activity, the researchers got new mice and cut the nerve that allows the gastrointestinal tract to communicate with the central nervous system. Then they fed these mice the broth, and the GABA receptors and mouse behavior remained at normal, pre-bacteria-enhanced levels.

This is not the first study to examine a connection between gut bacteria and psychological/brain physiological changes. Last summer, a British study found that the urine of autistic children has a distinct chemical signature associated with gut bacteria. Researchers at Imperial College London were not sure whether the bacteria were producing some kind of metabolic byproducts that could contribute to autism.

The Irish researchers say they still want to determine how the bacteria interact with the GABA receptors.

The chose L. rhamnosus because they happened to have it handy, and because related Lactobacillus species are so common in “probiotic” food supplements, ScienceNow reports. The bacteria is used to make foods like sourdough bread, yogurt and cheese. The paper was reported in the Proceedings of the National Academy of Sciences.

[via ScienceNow]

Sutures are an effective way to reconnect severed blood vessels, but they can introduce complications, for instance when cells are traumatized by the puncturing needle and clog up the vessel, which can lead to blood clots. What’s more, it’s difficult to suture blood vessels less than 1 millimeter wide, the Stanford team said. One of the authors on this study, Stanford microsurgeon Dr. Geoffrey Gurtner, was inspired to work on this problem a decade ago after a five-hour surgery in which he reattached the severed finger of a year-old infant, according to Stanford Medical School.

Sutures work by stitching together sides of a blood vessel and then tightening the stitch to pull open the lumen, or the inner part of the vessel, so the blood can flow through. Gluing a vessel together instead would require keeping the lumens open to their full diameter — think of trying to attach two deflated balloons. But dilating the lumen by inserting something inside introduces a wide range of problems, too.

Gurtner initially thought about using ice to fill up the lumen instead, but that meant making the vessels extremely cold, which would be too time-consuming and difficult on the operating table. He approached an engineering professor, Gerald Fuller, about using some kind of biocompatible phase change material, which could easily turn from a liquid to a solid and back again. It turned out Fuller knew of a thermo-reversible polymer, Poloxamer 407, that was already FDA approved for medical use.

Working with materials scientists, the team figured out how to modify the polymer so that it would become solid and elastic when heated warmer than body temperature, and would dissolve into the bloodstream at body temperature. In a study on rat aortas, the team heated it with a halogen lamp, and used the solidified polymer to fill up the lumen, opening it all the way. Then they used an existing bioadhesive to glue the blood vessels back together, a Stanford news release explains. The work was published in this week’s issue of Nature Medicine.

The polymer technique was five times faster than the traditional hand-sewing method, the researchers say. It even worked on superfine blood vessels, just 0.2 millimeters wide, which would not work with a needle and thread. The team monitored test subject rats for up to two years after the polymer suturing, and found no complications.

“This new technology has potential for improving efficiency and outcomes in the surgical treatment of cardiovascular disease,” the authors say.

In a small study, interventional cardiologists, who perform heart operations using catheters guided by x-rays, had higher levels of hydrogen peroxide in their blood, which indicates potentially harmful changes. But they also had higher levels of an antioxidant that protects against cell damage, and their white blood cells had more of an enzyme involved in programmed cell death.

Researchers in Italy believe the hydrogen peroxide indicates the radiation causes harm, and that this induces a protective response — the antioxidant, called glutathione, protects cells, and the enzyme that induces apoptosis could reflect the body’s way of killing off cells that have been damaged by radiation.

Scientists led by Gian Luigi Russo, a senior research scientist at the Italian National Research Council, examined 10 interventional cardiologists and 10 health workers who were not exposed to radiation. They examined the cardiologists’ radiation badges and extrapolated their lifetime exposure, and then took blood samples to test for hydrogen peroxide, glutathione and the enzyme caspase-3.

Interventional cardiologists receive a higher annual radiation dose than radiologists, because of the way they do their work. A patient is exposed to high radiation levels so the doctor can see the catheter they’re using to perform certain minimally invasive heart procedures. To do this, the cardiologist has to work close to the radiation source. These x-ray guided procedures have nearly doubled from 1993 to 2006, the researchers report — meaning the relatively small doses add up over time.

“Our findings clearly emphasize for the first time that exposure to a level of radiation which is considered ‘safe’ by regulatory standards for interventional cardiologists can induce a profound biochemical and cellular adaptation,” Russo said in a news release.

Doctors should not stop working with radiation, he noted — they just need to ensure their own protection.

“A good cardiologist should not be afraid of life-saving radiation, but must be afraid of radiation unawareness and negligence.”

The research is published in the European Heart Journal.

[via LiveScience]