Bio · Technology · Vital-Edible-Health

Nanoparticles may harm the brain

A simple change in electric charge may make the difference between someone getting the medicine they need and a trip to the emergency room—at least if a new study bears out. Researchers investigating the toxicity of particles designed to ferry drugs inside the body have found that carriers with a positive charge on their surface appear to cause damage if they reach the brain.

These particles, called micelles, are one type of a class of materials known as nanoparticles. By varying properties such as charge, composition, and attached surface molecules, researchers can design nanoparticles to deliver medicine to specific body regions and cell types—and even to carry medicine into cells. This ability allows drugs to directly target locations they would otherwise be unable to, such as the heart of tumors. Researchers are also looking at nanoparticles as a way to transport drugs across the blood-brain barrier, a wall of tightly connected cells that keeps most medication out of the brain. Just how safe nanoparticles in the brain are, however, remains unclear.

So Kristina Bram Knudsen, a toxicologist at the National Research Centre for the Working Environment in Copenhagen, and colleagues tested two types of micelles, which were made from different polymers that gave the micelles either a positive or negative surface charge. They injected both versions, empty of drugs, into the brains of rats, and 1 week later they checked for damage. Three out of the five rats injected with the positively charged micelles developed brain lesions. The rats injected with the negatively charged micelles or a saline control solution did not suffer any observable harm from the injections, the team will report in an upcoming issue of Nanotoxicology.

Knudsen speculates that one of the attributes that makes positive micelles and similar nanoparticles such powerful drug delivery systems may also be what is causing the brain damage. Because cells have a negative charge on their outside, they attract positively charged micelles and bring them into the cell. The micelles’ presence in the cell or alteration of the cell’s surface charge, she says, may disrupt the cell’s normal functioning.

Negatively charged nanoparticles can also enter cells, according to other research. However, they do so less readily and must be able to overcome the repulsion between themselves and the cell surface. It is possible that the reason the negatively charged micelles were not found to be toxic was that they did not invade cells to the same extent as the positively charged micelles.

The findings are intriguing, says biomedical engineer Jordan Green of Johns Hopkins University in Baltimore, Maryland. But he cautions that there is no evidence that all positively charged nanoparticles behave this way. Other factors can also play a role in the toxicity of nanoparticles, adds pharmaceutical expert Jian-Qing Gao of Zhejiang University in Hangzhou, China. The size and concentration of the particles, as well as the strain of rat used, could all have influenced the results, he says.

Text and Image via ScienceMag

Bio · Science · Technology · Theory · Vital-Edible-Health

Cancer’s origins revealed

Researchers have provided the first comprehensive compendium of mutational processes that drive tumour development. Together, these mutational processes explain most mutations found in 30 of the most common cancer types. This new understanding of cancer development could help to treat and prevent a wide-range of cancers.

Each mutational process leaves a particular pattern of mutations, an imprint or signature, in the genomes of cancers it has caused. By studying 7,042 genomes of people with the most common forms of cancer, the team uncovered more than 20 signatures of processes that mutate DNA. For many of the signatures, they also identified the underlying biological process responsible.

All cancers are caused by mutations in DNA occurring in cells of the body during a person’s lifetime. Although we know that chemicals in tobacco smoke cause mutations in lung cells that lead to lung cancers and ultraviolet light causes mutations in skin cells that lead to skin cancers, we have remarkably little understanding of the biological processes that cause the mutations which are responsible for the development of most cancers.

Read full article HERE

Bio · Science · Technology

How to turn living cells into computers: Genetic system performs logic operations and stores data in DNA

Synthetic biologists have developed DNA modules that perform logic operations in living cells. These ‘genetic circuits’ could be used to track key moments in a cell’s life or, at the flick of a chemical switch, change a cell’s fate, the researchers say. Their results are described this week in Nature Biotechnology.

Synthetic biology seeks to bring concepts from electronic engineering to cell biology, treating gene functions as components in a circuit. To that end, researchers at the Massachusetts Institute of Technology (MIT) in Cambridge have devised a set of simple genetic modules that respond to inputs much like the Boolean logic gates used in computers.

Excerpt from an article written by Roland Pease at Nature. Continue HERE

Bio · Human-ities · Science · Technology

ENCODE: the rough guide to the human genome

Back in 2001, the Human Genome Project gave us a nigh-complete readout of our DNA. Somehow, those As, Gs, Cs, and Ts contained the full instructions for making one of us, but they were hardly a simple blueprint or recipe book. The genome was there, but we had little idea about how it was used, controlled or organized, much less how it led to a living, breathing human.

That gap has just got a little smaller. A massive international project called ENCODE – the Encyclopedia Of DNA Elements – has moved us from “Here’s the genome” towards “Here’s what the genome does”. Over the last 10 years, an international team of 442 scientists have assailed 147 different types of cells with 24 types of experiments. Their goal: catalog every letter (nucleotide) within the genome that does something. The results are published today in 30 papers across three different journals, and more.

For years, we’ve known that only 1.5 percent of the genome actually contains instructions for making proteins, the molecular workhorses of our cells. But ENCODE has shown that the rest of the genome – the non-coding majority – is still rife with “functional elements”. That is, it’s doing something.

Excerpt from an article by Discover. Continue HERE

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Tissue on Demand and Bioprinting

Via Printerinks

Bio · Science

New type of extra-chromosomal DNA discovered

A team of scientists from the University of Virginia and University of North Carolina in the US have discovered a previously unidentified type of small circular DNA molecule occurring outside the chromosomes in mouse and human cells. The circular DNA is 200-400 base pairs in length and consists of non-repeating sequences. The new type of extra-chromosomal circular DNA (eccDNA) has been dubbed microDNA. Unlike other forms of eccDNA, in microDNA the sequences of base pairs are non-repetitive and are usually found associated with particular genes. This suggests they may be produced by micro-deletions of small sections of the chromosomal DNA.

This result suggests that the DNA found in tissue cells may exhibit more variation than previously thought, and the implication of this is that sequencing of the DNA in blood cells (which are the cells usually used for sequencing) may give misleading results if micro-deletions have occurred in the DNA of other tissues but not in blood cells. Examples in which this might be important are in genetic sequencing for autism or schizophrenia, which could be caused by incorrect functioning of certain genes in brain tissue. Many cancers are also caused by incorrect functioning of genes; in this case tumor suppressor genes, and sequencing of blood cell DNA could also give misleading results.

Excerpts from an article via PhysOrg