Irandaily | No. 4437 | Science

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Micro-Needles Facilitate DNA Vaccines

Patches covered in microscopic needles could tattoo vaccines into the skin to boost a patient’s defense against disease, researchers say.
Vaccines help bodies develop immunity to diseases by exposing immune systems to potential invaders, LiveScience said.
Scientists are now developing DNA vaccines that deliver genes from contagions into patients; the cells of vaccinated people then churn out molecules from those potential intruders that function like wanted signs, helping immune systems recognize dangerous threats.

Many Benefits
In principle, DNA vaccines possess a number of benefits over regular vaccines. For example, instead of wasting time and resources generating and purifying proteins from germs for use in vaccines, manufacturers can simply get the human body to do the manufacturing work.
So far, DNA vaccines have not proven very effective in humans, perhaps because there has been no good way to give patients enough of the vaccine in a shot.
Scientists have tried a number of strategies to make DNA vaccines more effective, for instance, using electrical zaps that make cells more permeable to DNA. However, this approach can be painful.
Instead, researchers at MIT sought to deliver DNA vaccines using arrays of microscopic plastic needles only 250 microns wide and 650 microns high. By comparison, the average human hair is about 100 microns wide.
Researchers coat these micro-needles with biodegradable films containing the vaccine as well as a variety of other molecules, such as compounds that stimulate immune systems and help cells absorb DNA. Applying patches loaded with these needles onto the skin instantly embeds the coatings into the body, much like the application of a tattoo.
These micro-needles can disrupt only the most superficial layers of the skin to avoid nerve endings and blood vessels, making them painless and safer than hypodermic needles.
“Comparing it to feeling like a cat’s tongue is quite accurate,” researcher Peter DeMuth, a biological engineer and materials scientist at MIT, told TechNewsDaily.
Advantages
The coatings remain implanted even after the micro-needle patches are pulled off. Coatings also dissolve in a controlled manner, releasing the vaccine and companion molecules over a sustained, and adjustable, period of time, which can be from days to weeks.
“We have very direct control over how the vaccine is delivered, and the prolonged exposure to the vaccine that is possible with this system can really enhance immunity,” DeMuth said.
Scientists tested the patches on rhesus monkeys, measuring how much of a protein encoded by a DNA vaccine the animals would produce. The monkeys generated 140 times as much of the protein in response to micro-needles as they did when injected using normal, hypodermic needles.

Some Berry Benefits Stop in Mouth

Research has suggested that compounds that give colorful fruits their rich hues, especially berries, promote health and might even prevent cancer.
But for the first time, scientists have exposed extracts from numerous berries high in those pigments to human saliva to see just what kinds of health-promoting substances are likely to survive and be produced in the mouth, ScienceDaily wrote.
It’s too early to name the best berry for health promotion based on this initial work. But the researchers have discovered that two families of pigments that provide berries with their colors, called anthocyanins, are more susceptible to degradation in the mouth than are the other four classes of these pigments.
The Ohio State University study also showed that bacteria living in the mouth are responsible for most of the breakdown of these compounds that occurs in saliva.

Researches
Researchers are investigating whether it’s the berry pigments themselves, or instead the products of their degradation, that actually promote health.
Scientists say that these early findings will contribute to the further development of confectionaries, gums and other delivery devices for the prevention and possibly the treatment of conditions such as periodontal disease and oral cancers.
The researchers exposed extracts of anthocyanin pigments from blueberries, chokeberries, black raspberries, red grapes and strawberries to the saliva collected from 14 people.
Black raspberries, in particular, have been shown in numerous previous studies to have chemo-preventive effects on tumors in the mouth, esophagus and colon, mostly in animal studies. Their high anthocyanin content has been linked to those benefits.
“All fruits are unique because their chemical composition, or fingerprint, varies,” said Mark Failla, professor of human nutrition at Ohio State and interim chair of the Department of Human Sciences.
“There are many different edible berries. Some might be better for providing health-promoting effects within the oral cavity, whereas others may be more beneficial for colonic health. We simply do not know at this time.”

Lower Risk of Chronic Diseases
Increased intake of fruits and vegetables is associated with decreased risk of some chronic diseases. An understanding of the metabolism of these compounds, and the relative activities of the compounds in the consumed fruit and their metabolic products, is needed to make scientifically sound dietary recommendations and to develop effective delivery vehicles for the mouth.
Failla and colleagues asked 14 healthy individuals between the ages of 21 and 55 years to collect saliva in the morning before they had eaten breakfast or brushed their teeth.

Process That Controls Tomato Ripening

Everyone loves a juicy, perfectly ripened tomato, and scientists have long sought ways to control the ripening process to improve fruit quality and prevent spoilage.
A new study by researchers at the Boyce Thompson Institute for Plant Research (BTI) and the US Department of Agriculture’s Agricultural Research Service (ARS), both on the Cornell campus, reveals that epigenetics, a set of chemical changes to a plant’s DNA, plays a pivotal role in tomato ripening, signaling to the fruit when the time is right to redden, Physorg wrote.
The discovery opens the door to new ways of thinking about how to develop varieties of tomatoes that can survive the trip from the farm to the grocery store with flavor and texture intact. The paper was published on the journal Nature Biotechnology’s website.
“Most previous breeding efforts were focused on the DNA sequence variation in the genome,” says Zhangjun Fei, a co-author on the paper and an associate professor at BTI. “This opens a new era. Now it’s possible to use epigenetic variation rather than just changes in DNA sequence to breed better crops.”
In recent years, scientists have discovered that in addition to the instructions contained in an organism’s DNA, there is also a layer of epigenetic information superimposed on that DNA that can control how and when genes are expressed. In one common epigenetic modification, methyl groups are attached to sites on an organism’s DNA, and heavy methylation can essentially shut down a gene.
In his laboratory at BTI, ARS molecular biologist James Giovannoni and his colleagues took up the question of whether epigenetics might play a role in tomato ripening. The ripening hormone ethylene is made in plant tissues but can also be applied in tomato processing to ripen the fruit for market.
Very young tomatoes, with immature seeds, do not ripen in response to ethylene, and scientists have tried without success to understand the genetic trigger that signals to the tomato flesh that maturation has been reached.
To test whether epigenetics might be at work in this ripening trigger, researchers injected unripe tomatoes with a compound that inhibits the enzymes that methylate DNA. The tomatoes ripened prematurely, a strong indication that DNA methylation regulates ripening.