Artificial Liver For Drug Tests.

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ScienceDaily (June 25, 2009) — If you have hay fever, headaches or a cold, it’s only a short way to the nearest chemist. The drugs, on the other hand, can take eight to ten years to develop. Until now animal experiments have been an essential step, yet they continue to raise ethical issues. “Our artificial organ systems are aimed at offering an alternative to animal experiments,” says Professor Heike Mertsching of the Fraunhofer Institute for Interfacial Engineering and Biotechnology IGB in Stuttgart.

“Particularly as humans and animals have different metabolisms. 30 per cent of all side effects come to light in clinical trials.” The test system, which Professor Mertsching has developed jointly with Dr. Johanna Schanz, should in future give pharmaceutical companies greater security and shorten the path to new drugs. Both researchers received the “Human-centered Technology” prize for their work.
“The special feature, in our liver model for example, is a functioning system of blood vessels,” says Dr. Schanz. “This creates a natural environment for cells.” Traditional models do not have this, and the cells become inactive. “We don’t build artificial blood vessels for this, but use existing ones – from a piece of pig’s intestine.” All of the pig cells are removed, but the blood vessels are preserved. Human cells are then seeded onto this structure – hepatocytes, which, as in the body, are responsible for transforming and breaking down drugs, and endothelial cells, which act as a barrier between blood and tissue cells.
In order to simulate blood and circulation, the researchers put the model into a computer-controlled bioreactor with flexible tube pump, developed by the IGB. This enables the nutrient solution to be fed in and carried away in the same way as in veins and arteries in humans. “The cells were active for up to three weeks,” says Dr. Schanz. “This time was sufficient to analyze and evaluate the functions. A longer period of activity is possible, however.”
The researchers established that the cells work in a similar way to those in the body. They detoxify, break down drugs and build up proteins. These are important pre-conditions for drug tests or transplants, as the effect of a substance can change when transformed or broken down – many drugs are only metabolized into their therapeutic active form in the liver, while others can develop poisonous substances. The researchers have demonstrated the basic possibilities for use of the tissue models – liver, skin, intestine and windpipe. At the moment, the test system is being examined. Within two years it could provide a safer alternative to animal experiments.
Adapted from materials provided by Fraunhofer-Gesellschaft.

Contrary to predictions, males of high genetic quality are not very successful when it comes to fertilizing eggs.

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Contrary to predictions, males of high genetic quality are not very successful when it comes to fertilizing eggs. A new study on seed beetles by Swedish and Danish scientists Göran Arnqvist and Trine Bilde shows that when a female mates with several males, the males of low genetic quality are the most successful in fertilizing eggs. The study is published in this week's issue of Science.

In almost all animals, females mate with several different males, despite the fact that a single mating is often sufficient to fertilize her eggs. Multiple mating also carries costs to females, such as the risk of catching sexually transmitted diseases.
One commonly held belief is that this behaviour may allow females to choose the sperm of the male with highest genetic quality to fertilize her eggs. Professor Göran Arnqvist from the Department of Ecology and Evolution, Uppsala University and associate professor Trine Bilde from the Department of Biological Sciences, University of Aarhus, have tested this possibility directly for the first time and shown that it is not true.
Their study on seed beetles shows that, contrary to predictions, males of low genetic quality are more successful in fertilizing eggs. Males who gained the highest share of paternity were actually males with low genetic quality. These males also fathered offspring that did less well.
"The results support the suggestion that genes that are good for males may often be bad for their mates. Therefore, in beetles at least, multiple mating does not award females with genetic benefits," says Göran Arnqvist.
Source: Uppsala University (news : web)

Nanocrystals Reveal Activity Within Cells

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ScienceDaily (June 18, 2009) — Researchers at the U.S. Department of Energy’s (DOE) Lawrence Berkeley National Laboratory have created bright, stable and bio-friendly nanocrystals that act as individual investigators of activity within a cell. These ideal light emitting probes represent a significant step in scrutinizing the behaviors of proteins and other components in complex systems such as a living cell.

Labeling a given cellular component and tracking it through a typical biological environment is fraught with issues: the probe can randomly turn on and off, competes with light emitting from the cell, and often requires such intense laser excitation, it eventually destroys the probe, muddling anything you’d be interested in seeing.
“The nanoparticles we’ve designed can be used to study biomolecules one at a time,” said Bruce Cohen, a staff scientist in the Biological Nanostructures Facility at Berkeley Lab’s nanoscience research center, the Molecular Foundry. “These single-molecule probes will allow us to track proteins in a cell or around its surface, and to look for changes in activity when we add drugs or other bioactive compounds.”
Molecular Foundry post-doctoral researchers Shiwei Wu and Gang Han, led by Cohen, Imaging and Manipulation of Nanostructures staff scientist Jim Schuck and Inorganic Nanostructures Facility Director Delia Milliron, worked to develop nanocrystals containing rare earth elements that absorb low-energy infrared light and transform it into visible light through a series of energy transfers when they are struck by a continuous wave, near-infrared laser. Biological tissues are more transparent to near-infrared light, making these nanocrystals well suited for imaging living systems with minimal damage or light scatter.
“Rare earths have been known to show phosphorescent behavior, like how the old-style television screen glows green after you shut it off. These nanocrystals draw on this property, and are a million times more efficient than traditional dyes,” said Schuck. “No probe with ideal single-molecule imaging properties had been identified to date—our results show a single nanocrystal is stable and bright enough that you can go out to lunch, come back, and the intensity remains constant.”
To study how these probes might behave in a real biological system, the Molecular Foundry team incubated the nanocrystals with embryonic mouse fibroblasts, cells crucial to the development of connective tissue, allowing the nanocrystals to be taken up into the interior of the cell. Live-cell imaging using the same near-infrared laser showed similarly strong luminescence from the nanocrystals within the mouse cell, without any measurable background signal.
“While these types of particles have existed in one form or another for some time, our discovery of the unprecedented ’single-molecule’ properties these individual nanocrystals possess opens a wide range of applications that were previously inaccessible,” Schuck adds.
“Non-blinking and photostable upconverted luminescence from single lanthanide-doped nanocrystals,” by Shiwei Wu, Gang Han, Delia J. Milliron, Shaul Aloni, Virginia Altoe, Dmitri Talapin, Bruce E. Cohen and P. James Schuck, appears in Proceedings of the National Academy of Sciences and is available in Proceedings of the National Academy of Sciences online.
Work at the Molecular Foundry was supported by the Office of Basic Energy Sciences within the DOE Office of Science.
Adapted from materials provided by DOE/Lawrence Berkeley National Laboratory.

Chemists see first building blocks to life on Earth

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British scientists said on Wednesday that they had figured out key steps in the process by which life on Earth may have emerged from a seething soup of simple chemicals.

Genetic information in living organisms today is held in deoxyribonucleic acid (DNA), the famous "double helix" molecule of sugar, phosphate and a base.
But DNA is too sophisticated to have popped up in an instant, and one avenue of thought says its single-stranded cousin, ribonucleic acid, or RNA, came first.
RNA plays a key role in making proteins and, in viruses, is used to store genetic code.
It is chemically similar to DNA but is simpler and tougher in structure, and thus looks like a good candidate for Earth's first information-coding nucleic acid.
But for all its allure, the "RNA first" theory has run into practical problems.
Its three ingredients -- the base, ribose sugar and phosphate -- must have formed separately and then combined to form the molecule, according to conventional thinking.
Critics, though, say that RNA, while somewhat simpler than DNA, is still a complex molecule and could not have been assembled spontaneously.
These doubters have been comforted by the failure to find any feasible chain of chemical events to explain how the three components all came together.
But a paper published in the British journal Nature by University of Manchester chemists puts forward a different explanation.
The team, led by Professor John Sutherland, venture that an RNA-like synthesis took place through a series of chemical reactions and an important intermediate substance.
Their lab model uses starting materials and environmental conditions that are believed to have been around in early Earth and are also used in the standard "RNA first" scenario.
Their theory starts with a simple sugar called glycolaldehyde, which reacts with cyanmide (a compound of cyanide and ammonia) and phosphate to produce an intermediate compound called 2-aminooxazole.
Gentle warming from the Sun and cooling at night help purify the 2-aminooxazole, turning it into a plentiful precursor which contributes the sugar and base portions of the new ribonucleotide molecule.
The presence of phosphate and ultraviolet light from the Sun complete the synthesis.
In a commentary also published by Nature, US molecular biologist Jack Szostak hailed the research as an elegant explanation as to why the sugar and base would not have to form separately before forming the new molecule.
"It will stand for years as one of the great advances in prebiotic chemistry," the term for the study of the chemical processes that led to life on Earth, he enthused.
Opinions vary as to when the first organisms appeared on Earth.
One estimate, based on fossilised mats of bacteria found in Australia, is that this happened around 3.8 billion years ago, around 700 million years after the planet was formed.
(c) 2009 AFP

Developed a human monoclonal antibody that neutralizes the Hepatitis C virus (HCV).

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ScienceDaily (May 11, 2009) — aking aim at a leading cause of liver failure in the United States, a team of scientists at the Massachusetts Biologic Laboratories (MBL) of the University of Massachusetts Medical School (UMMS) has developed a human monoclonal antibody that neutralizes the Hepatitis C virus (HCV). The new antibody effectively neutralized the virus in culture, and then prevented infection by the virus in a pre-clinical animal model of the disease.

Details of the research were presented April 23 in Copenhagen, Denmark at the 44th Annual Meeting of the European Association for the Study of the Liver (EASL). "We are pleased with the progress of this program," said Donna Ambrosino, MD, executive director of the MBL and a professor of pediatrics at the Medical School. "This antibody shows significant efficacy against the virus."
In the current study, MBL scientists injected transgenic mice (HuMAb Mouse® technology, Medarex, Inc.) with elements of HCV and then painstakingly searched for individual human antibodies produced in the mice that would recognize and bind to the HCV's outer coat, known as the glycoprotein. Once they found human antibodies that looked promising, they evaluated in vitro the ability of those antibodies to neutralize the virus and selected a lead candidate antibody for further characterization. Collaborative work with clinical researchers from the Department of Medicine at the Medical School's Worcester campus demonstrated that this antibody, now known as MBL-HCV1, was able to bind tightly with all genotypes of HCV tested from infected patient samples.
MBL-HCV1 was then tested off-site on three non-human primates. In that study, one animal received no antibody, one a low dose of the new antibody, and one a higher dose. Then all three animals were exposed to HCV. The animals with low or no antibody dosages developed HCV infections, but the animal with the higher dose was protected. Subsequently, researchers gave the high-dose of the antibody to the animal that originally received no antibody, and in that case the HCV was cleared from that animal's system. "These results are encouraging as a possible treatment for HCV infected patients, but more work needs to be done before we know how effective it will be in people," Dr. Ambrosino noted.
HCV attacks the liver and can eventually lead to liver failure. According to the U.S. Centers for Disease Control and Prevention, 3.2 million Americans are chronically infected with HCV and some 10,000 die annually of the disease. Globally, as many as 170 million people are estimated to suffer from HCV infection. For the most serious cases of HCV that do not respond to antiviral drugs, liver transplantation is the only option.
Typically 2,000 to 4,000 liver transplants are done each year in the United States (far less than the number of people on the waiting list for available organs). Transplantation can be a life saving treatment; however, in nearly all cases the patient's new liver is eventually infected by HCV because the virus remains in the patient's bloodstream during surgery. The powerful antiviral drugs now used to attack HCV prior to end-stage liver failure are not routinely used during surgery due to the patients' weakened condition and because of the strong medication used to avoid rejection of the new liver. After re-infection with HCV, nearly 40 percent of patients suffer rapid liver failure.
To close that clinical gap, the new antibody developed at MBL is designed to be a therapy shortly before and after transplant surgery. By giving a patient the new antibody before and during the time when the donor liver is implanted, researchers hope the HCV virus left in the bloodstream will be neutralized and rendered unable to infect the new liver. Then, because monoclonal antibodies are highly specific and typically have little or no side-effects, additional dosages of the new antibody could, theoretically, be given immediately after transplant surgery to continue neutralizing any remaining virus.
It is also possible, researchers theorize, that the antibody could be used in combination with new antiviral drugs for treatment in patients with newly diagnosed HCV infection. Use of the new antibody for both liver transplant patients and in newly diagnosed HCV patients will now be further evaluated. A Phase 1 human clinical trial of MBL-HCV1 in healthy subjects is expected to begin later this year.
Adapted from materials provided by University of Massachusetts Medical School, via EurekAlert!, a service of AAAS.

Sexually Transmitted Infections: Transistors Used To Detect Fungus Candida Albicans

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ScienceDaily (May 11, 2009) — The Nanosensors group from the Universidad Rovira i Virgili has created a biosensor, an electrical and biological device, which is able to selectively detect the Candida albicans yeast in very small quantities of only 50 cfu/ml (colony-forming units per millilitre).

"The technique uses field-effect transistors (electronic devices that contain an electrode source and a draining electrode connected to a transducer) based on carbon nanotubes and with Candida albicans-specific antibodies", Raquel A. Villamizar, lead author of the study said.
The Candida samples, which can be obtained from blood, serum or vaginal secretions, are placed directly on the biosensor, where the interaction between antigens and antibodies changes the electric current of the devices. This change is recorded and makes it possible to measure the amount of yeast present in a sample.
"Thanks to the extraordinary charge transference properties of the carbon nanotubes, the fungus detection process is direct, fast, and does not require the use of any marker", remarks Villamizar, who is co-author of a study that provides details of the biosensor and was published recently in the journal Sensors and Actuators B: Chemical.
To date, conventional diagnosis of Candida has been carried out using microbial cultures, serological tests, PCR molecular biology techniques (polymerase chain reactions used to amplify DNA), or immunoassays such as ELISA (Enzyme Linked Inmunoabsorbent Assay).
These techniques require long analysis times and sometimes give rise to false positives and negatives. ELISA also requires the use of markers (compounds that must be added to detect the presence of yeast by fluorescence and other techniques).
The new carbon nanotubes biosensor, however, "makes it possible to improve some of the quality parameters of the traditional methods, for example the speed and simplicity of measurements, and it is an alternative tool that could be used in routine sample analysis", explains Villamizar.
The researcher adds that by using this biosensor "it will be possible in future to obtain a rapid diagnosis of infection with this pathogen, which will help to ensure administration of the correct prophylactic treatments".
The Candida albicans fungus exists naturally in the skin, mouth, the mucous membranes lining the digestive tract, and the respiratory and genitourinary systems. This yeast can cause anything from simple mycosis of the skin to complicated cases of candidiasis. It is much more commonly found in patients suffering from immunodeficiency, tumours, diabetes and lymphomas, among other diseases.
Journal reference:
Villamizar et al. Improved detection of Candida albicans with carbon nanotube field-effect transistors. Sensors and Actuators B Chemical, 2009; 136 (2): 451 DOI: 10.1016/j.snb.2008.10.013
Adapted from materials provided by Plataforma SINC.

Making Gene Therapy Safer: Delivering Genes Via Polymers

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http://www.sciencedaily.com/releases/2007/09/070907095614.htm

Science Daily — In work that could lead to safe and effective techniques for gene therapy, MIT researchers have found a way to fine-tune the ability of biodegradable polymers to deliver genes.

Gene therapy, which involves inserting new genes into patients' cells to fight diseases like cancer, holds great promise but has yet to realize its full potential, in part because of safety concerns over the conventional technique of using viruses to carry the genes.
The new MIT work, published this week in Advanced Materials, focuses on creating gene carriers from synthetic, non-viral materials. The team is led by Daniel Anderson, research associate in MIT's Center for Cancer Research.
"What we wanted to do is start with something that's very safe-a biocompatible, degradable polymer-and try to make it more effective, instead of starting with a virus and trying to make it safer," said Jordan Green, a graduate student in biological engineering and co-first author of the paper.
Gregory Zugates, a former graduate student in chemical engineering now at WMR Biomedical, Inc., is also a co-first author of the paper.
Gene therapy has been a field of intense research for nearly 20 years. More than 1,000 gene-therapy clinical trials have been conducted, but to date there are no FDA-approved gene therapies. Most trials use viruses as carriers, or vectors, to deliver genes.
However, there are risks associated with using viruses. As a result, many researchers have been working on developing non-viral methods to deliver therapeutic genes.
The MIT scientists focused on three poly(beta-amino esters), or chains of alternating amine and diacrylate groups, which had shown potential as gene carriers. They hoped to make the polymers even more efficient by modifying the very ends of the chains.
When mixed together, these polymers can spontaneously assemble with DNA to form nanoparticles. The polymer-DNA nanoparticle can act in some ways like an artificial virus and deliver functional DNA when injected into or near the targeted tissue.
The researchers developed methods to rapidly optimize and test new polymers for their ability to form DNA nanoparticles and deliver DNA. They then chemically modified the very ends of the degradable polymer chains, using a library of different small molecules.
"Just by changing a couple of atoms at the end of a long polymer, one can dramatically change its performance," said Anderson. "These minor alterations in polymer composition significantly increase the polymers' ability to deliver DNA, and these new materials are now the best non-viral DNA delivery systems we've tested."
The polymers have already been shown to be safe in mice, and the researchers hope to ultimately run clinical trials with their modified polymers, said Anderson.
Non-viral vectors could prove not only safer than viruses but also more effective in some cases. The polymers can carry a larger DNA payload than viruses, and they may avoid the immune system, which could allow multiple therapeutic applications if needed, said Green.
One promising line of research involves ovarian cancer, where the MIT researchers, in conjunction with Janet Sawicki at the Lankenau Institute for Medical Research, have demonstrated that these polymer-DNA nanoparticles can deliver DNA at high levels to ovarian tumors without harming healthy tissue.
Other MIT authors on the paper are Nathan Tedford, a former graduate student in biological engineering now at Epitome Biosystems; Linda Griffith, professor of biological engineering; Douglas Lauffenberger, head of biological engineering, and Institute Professor Robert Langer. Sawicki and Yu-Hung Huang of the Lankenau Institute are also co-authors.
The research was funded by the National Institutes of Health, the Department of Defense and the National Science Foundation.
Note: This story has been adapted from a news release issued by Massachusetts Institute of Technology.

Fausto Intilla

www.oloscience.com