More evidence for possible link between cocaine use and HIV infection

 

New UCLA research offers further evidence that cocaine use disrupts the immune system, making people who use it more likely to become infected with HIV. In research published online June 18 in the peer-reviewed journal Scientific Reports, researchers with the UCLA AIDS Institute and Center for AIDS Research used an advanced form of humanized mice -- that is, immunodeficient mice engineered to have a human-like immune system -- to study the effects of cocaine. The findings suggest that using cocaine makes people significantly more susceptible to HIV infection. 'Substance use and abuse is a major issue, especially when it comes to HIV infection,' said Dimitrios Vatakis, the study's senior author and an assistant professor of medicine in the division of hematology/oncology at the David Geffen School of Medicine at UCLA. 'There has been a general attitude, especially in the scientific but also the general community, that risky behavior is the main reason for higher infections. This study shows that under the same transmission conditions, drug exposure enhances infection through a collective of biological changes.' This study builds on previous research by Vatakis and others on his team showing that a three-day exposure to cocaine appears to make a unique population of immune cells called quiescent CD4 T cells, which are resistant to HIV, more susceptible to infection by stimulating two receptors in the cells, called σ1 and D4. Those findings suggested that cocaine use increases the pool of CD4 T cells in the human body that can become infected by the virus. As a result, the odds for productive infection and a larger viral reservoir increase. That study, however, was based on in-vitro research -- that is, research done in a petri dish -- which could have skewed the results. The next step was to find the same effect in in-vivo studies -- that is, those conducted with living organisms, such as mice. This is what the current paper has done. For this study, Vatakis and his team used the most advanced humanized mouse model, called BLT. The name comes from the way the model is generated: mice are transplanted with human hematopoietic stem cells (B, for blood cells) and donor-matched liver (L) and thymus (T) tissues, resulting in the development of a functioning human immune system. 'This study is the first of its kind using this model,' said Vatakis, who also directs the UCLA/CFAR Virology Core Laboratory. 'The BLT has been used to study HIV latency, cancer immunotherapy and now drug abuse and HIV infection. It very closely resembles the human immune system and it is the most relevant.' The researchers separated the mice into two major groups. Half of the mice were injected with cocaine every day for five days, while the other half were injected with saline for comparison. After five days, half the mice in each group were injected with HIV-1. Then all of the mice were given saline or cocaine for two more weeks. The researchers then collected blood and tissue samples to measure infection levels and examine other effects of the cocaine. They found that the cocaine/HIV group had higher amounts of HIV than the saline/HIV mice. They also found that nine of the 19 saline/HIV mice had undetectable amounts of the virus, compared with only three of the 19 cocaine/HIV mice. The researchers were surprised to find that despite the cocaine-induced inflammation prior to infection, the CD4 T cells that HIV targets were not overtly activated. Also, CD8 T cells, which kill infected cells, were not functional, even though they appeared to be so. 'This points to cocaine blunting the potency of our body's defense against the virus,' Vatakis said. While these studies have shed further light on the effects of cocaine use and misuse on HIV infection, this small animal model, although it closely mimics human immunity, does not fully re-create real-life settings. In addition, the study used an acute -- or brief, uninterrupted -- cocaine exposure regimen, rather than a more clinically relevant chronic use model, which could affect the results. The next stages of research, using the same BLT model, will be to determine how cocaine abuse might affect HIV transmission in mucosal membranes such as vaginal and anal tissues; how pre- and post-exposure prophylaxis (that is, taking medication to reduce the risk of acquiring HIV) can be affected by cocaine exposure; how cocaine might affect viral latency, the process in which a virus lies dormant in a cell; and how cocaine alters the body's immune defenses and affects other viral infections. Story Source: The above post is reprinted from materials provided by University of California - Los Angeles Health Sciences. Note: Materials may be edited for content and length. Journal Reference: Sohn G. Kim, Emily L. Lowe, Dhaval Dixit, Cindy Seyeon Youn, Irene J. Kim, James B. Jung, Robert Rovner, Jerome A. Zack, Dimitrios N. Vatakis. Cocaine-mediated impact on HIV infection in humanized BLT mice. Scientific Reports, 2015; 5: 10010 DOI: 10.1038/srep10010

Chemists devise technology that could transform solar energy storage

 

Fri, 06/19/2015 - 8:19am Melody Pupols, Univ. of California, Los Angeles   The scientists devised a new arrangement of solar cell ingredients, with bundles of polymer donors (green rods) and neatly organized fullerene acceptors (purple, tan). Image: UCLA ChemistryThe materials in most of today’s residential rooftop solar panels can store energy from the sun for only a few microseconds at a time. A new technology developed by chemists at the Univ. of California, Los Angeles (UCLA) is capable of storing solar energy for up to several weeks—an advance that could change the way scientists think about designing solar cells. The findings are published in Science. The new design is inspired by the way that plants generate energy through photosynthesis. “Biology does a very good job of creating energy from sunlight,” said Sarah Tolbert, a UCLA professor of chemistry and one of the senior authors of the research. “Plants do this through photosynthesis with extremely high efficiency.” “In photosynthesis, plants that are exposed to sunlight use carefully organized nanoscale structures within their cells to rapidly separate charges—pulling electrons away from the positively charged molecule that is left behind, and keeping positive and negative charges separated,” Tolbert said. “That separation is the key to making the process so efficient.” To capture energy from sunlight, conventional rooftop solar cells use silicon, a fairly expensive material. There is currently a big push to make lower-cost solar cells using plastics, rather than silicon, but today’s plastic solar cells are relatively inefficient, in large part because the separated positive and negative electric charges often recombine before they can become electrical energy. “Modern plastic solar cells don’t have well-defined structures like plants do because we never knew how to make them before,” Tolbert said. “But this new system pulls charges apart and keeps them separated for days, or even weeks. Once you make the right structure, you can vastly improve the retention of energy.” The two components that make the UCLA-developed system work are a polymer donor and a nanoscale fullerene acceptor. The polymer donor absorbs sunlight and passes electrons to the fullerene acceptor; the process generates electrical energy. The plastic materials, called organic photovoltaics, are typically organized like a plate of cooked pasta—a disorganized mass of long, skinny polymer “spaghetti” with random fullerene “meatballs.” But this arrangement makes it difficult to get current out of the cell because the electrons sometimes hop back to the polymer spaghetti and are lost. The UCLA technology arranges the elements more neatly—like small bundles of uncooked spaghetti with precisely placed meatballs. Some fullerene meatballs are designed to sit inside the spaghetti bundles, but others are forced to stay on the outside. The fullerenes inside the structure take electrons from the polymers and toss them to the outside fullerene, which can effectively keep the electrons away from the polymer for weeks. “When the charges never come back together, the system works far better,” said Benjamin Schwartz, a UCLA professor of chemistry and another senior co-author. “This is the first time this has been shown using modern synthetic organic photovoltaic materials.” In the new system, the materials self-assemble just by being placed in close proximity. “We worked really hard to design something so we don’t have to work very hard,” Tolbert said. The new design is also more environmentally friendly than current technology, because the materials can assemble in water instead of more toxic organic solutions that are widely used today. “Once you make the materials, you can dump them into water and they assemble into the appropriate structure because of the way the materials are designed,” Schwartz said. “So there’s no additional work.” The researchers are already working on how to incorporate the technology into actual solar cells. Yves Rubin, a UCLA professor of chemistry and another senior co-author of the study, led the team that created the uniquely designed molecules. “We don’t have these materials in a real device yet; this is all in solution,” he said. “When we can put them together and make a closed circuit, then we will really be somewhere.” For now, though, the UCLA research has proven that inexpensive photovoltaic materials can be organized in a way that greatly improves their ability to retain energy from sunlight. Source: Univ. of California, Los Angeles