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Using a bone-creating protein to augment（增加） the maxillary sinus（上颌骨窦） could improve dental implant success, according to Georgia Health Sciences University researchers. Dental implants, screws that anchor permanent prosthetic（假体的） teeth, won’t work if the bone in which they are anchored is too thin. Bone-thinning is a common cause and consequence following tooth loss. The current favored solution is to supplement the area with bone grafts to stabilize the implant base. But that technique is problematic “primarily because it involves additional surgeries to harvest the bone,” said Dr. Ulf M.E. Wikesjö, Interim Associate Dean for Research and Enterprise in the GHSU College of Dental Medicine.In animal studies, he and his team at the GHSU Laboratory for Applied Periodontal & Craniofacial Regeneration found that implanting bone morphogenetic（形态产生的） protein in the sinus more new bone will form within four weeks than using conventional bone grafting at the same site.”We found that BMP induced superior bone quality over that following bone grafts, which improves the chances for successful implants,” Wikesjö said. “BMP is phenomenal, because it’s a true, off-the-shelf product with ease of use that can produce real results, and it could be the new gold standard for this procedure.”According to the American Association of Oral and Maxillofacial Surgeons, 69 percent of adults ages 35-44 have lost at least one tooth due to decay, disease or trauma（创伤） , and 26 percent of adults have lost all permanent teeth by age 74. Before dental implants were available, the only options for replacing these missing teeth were dentures（假牙） and dental bridges, both of which could lead to further bone loss. Implants provide patients with numerous benefits, including improved oral health, appearance, speech, convenience, durability and ability to eat.

A lack of vitamin D, even in generally healthy people, is linked with stiffer arteries and an inability of blood vessels to relax, research from the Emory/Georgia Tech Predictive Health Institute has found. The results add to evidence that lack of vitamin D can lead to impaired vascular（血管的） health, contributing to high blood pressure and the risk of cardiovascular disease. Study participants who increased their vitamin D levels were able to improve vascular health and lower their blood pressure.The data is being presented on Sunday by Ibhar Al Mheid, MD, a cardiovascular researcher at Emory University School of Medicine, at the annual American College of Cardiology meeting in New Orleans. Al Mheid is one of five finalists for the ACC’s Young Investigators Award competition in physiology, pharmacology and pathology. He is working with Arshed Quyyumi, MD, professor of medicine and director of the Emory Cardiovascular Research Institute.The 554 participants in the study were Emory or Georgia Tech employees –average age 47 and generally healthy — who are taking part in the Center for Health Discovery and Well Being, part of the Emory/Georgia Tech Predictive Health Institute.The average level of 25-hydroxyvitamin D (a stable form of the vitamin reflecting diet as well as production in the skin) in participants’ blood was 31.8 nanograms per milliliter. In this group, 14 percent had 25-hydroxyvitamin D levels considered deficient, or less than 20 nanograms per milliliter, and 33 percent had levels considered insufficient, less than 30 nanograms per milliliter.The researchers monitored the ability of participants’ blood vessels to relax by inflating and then removing a blood pressure cuff on their arms. To allow blood to flow back into the arm, blood vessels must relax and enlarge – a change that can be measured by ultrasound. The researchers also made other measurements of smaller blood vessels and examined the resistance to blood flow imposed by the arteries.Even after controlling for factors such as age, weight and cholesterol, people with lower vitamin D levels still had stiffer arteries and impaired vascular function, Al Mheid says.”We found that people with vitamin D deficiency had vascular dysfunction comparable to those with diabetes or hypertension,” he says.Throughout the body, a layer of endothelial cells（内皮细胞） lines the blood vessels, controlling whether the blood vessels constrict or relax and helping to prevent clots（血块） that lead to strokes and heart attacks.”There is already a lot known about how vitamin D could be acting here,” Al Mheid says. “It could be strengthening endothelial cells and the muscles surrounding the blood vessels. It could also be reducing the level of angiotensin, a hormone that drives increased blood pressure, or regulating inflammation.”

Using eyes made of a calcium carbonate（碳酸钙） crystal, a simple mollusk（软体动物） may have evolved enough vision to spot potential predators, scientists say. The three-inch-long mollusks, called chitons（石鳖） , have hundreds of eye-like structures with lenses made of aragonite, a type of rock. It’s the first time scientists have found an animal that makes eye lenses from aragonite and not the rock’s close cousin, calcite.”It’s surprising how these creatures make their eyes from rocks,” said Duke biologist Sönke Johnsen. Most animals make their eyes from cells with proteins and chitin. “But it seems like an easy way to evolve eyes by using what you’ve already got,” he said. Chitons also make their shells from aragonite.Johnsen and former Duke Ph.D. student Daniel Speiser studied West Indian fuzzy chitons, or Acanthopleura granulata, which have flat shells made of eight separate plates. Hundreds of tiny lenses on the surface of the plates cover clusters of light-sensitive cells beneath.Scientists discovered the eyes decades ago. But it wasn’t clear whether chitons used these eyes to see objects overhead or simply to sense changes in light. “Turns out they can see objects, though probably not well,” said Speiser, who recently became a post-doctoral fellow at the University of California, Santa Barbara. The results of the new chiton study appear in the April 26 Current Biology.To test the creature’s vision, Speiser placed individual chitons on a slate slab（厚板） . When left undisturbed, they would lift part of their armored, oval-shaped body to breathe. At this point, Speiser would show them either a black disk ranging from 0.35 centimeters to 10 centimeters in diameter or a corresponding gray slide that blocked the same amount of light. The disk or slide appeared 20 centimeters above the chitons.When shown the gray screens, the chitons did not respond. But they clamped down when shown a black disk 3 centimeters or larger in diameter. That would be the equivalent of humans looking in the sky and seeing a disk the diameter of 20 moons, making human vision about a thousand times sharper than chiton vision, Johnsen said.Because the chitons responded to the larger disks and not the gray slides, they seem to be seeing the disk and not simply responding to a change in light, said University of Sussex biologist Michael Land, an expert on animal vision who was not involved in the research. But it’s not yet clear if they respond only to the removal of light by the disk as opposed to added light.Land also said it’s not likely that the chitons’ eyes were part of the evolutionary route to human eyes.Chitons are ancient, primitive species that first appeared on Earth more than 500 million years ago. But the oldest chitons with eyes only began to appear in the fossil record in the last 25 million years, making their eyes among the most recent to evolve in animals. Speiser said chitons probably evolved to have eyes with lenses so they could see their predators and defend against being eaten.Speiser and his colleagues also tested whether the chitons’ eyes work in both air and water, since some species spend time in both. The experiments made a strong case for the chiton lens being able to focus light differently depending on whether the animal is above or below water, Land said.He added that chiton eyes are still an anomaly（异常，不法则） in the evolution of vision. The retinas are structurally similar to snail and slug（鼻涕虫） retinas. But snail and slug retinas respond to the appearance of light, while chiton retinas may only respond to the removal of light, a difference that might be worth another look, Land said.

Bremerhaven/Geesthacht/Potsdam, 14 April 2011. The coastline in Arctic regions reacts to climate change with increased erosion and retreats by half a metre per year on average. This means substantial changes for Arctic ecosystems near the coast and the population living there. A consortium（财团，结合） of more than thirty scientists from ten countries, including researchers from the Alfred Wegener Institute for Polar and Marine Research in the Helmholtz Association and from the Helmholtz Centre in Geesthacht, comes to this conclusion in two studies published in Estuaries and Coasts and online on www.arcticcoasts.org. They jointly investigated over 100,000 kilometres and thus a fourth of all Arctic coasts and their results have now been published for the first time. The changes are particularly dramatic in the Laptev, East Siberian and Beaufort Seas, where coastal erosion rates reach more than 8 metres a year in some cases. Since around a third of the world’s coasts are located in the Arctic permafrost（永久冻土） , coastal erosion may affect enormous areas in future. In general Arctic coasts react more sensitively to global warming than coasts in the mid-latitudes. Up to now they have been protected against the eroding force of the waves by large sea ice areas. Due to the continuous decline in sea ice, this protection is jeopardised and we have to reckon with rapid changes in a situation that has remained stable for millennia.Two thirds of the Arctic coasts do not consist of rock, but of frozen soft substrate (permafrost). And precisely these coasts are extremely hard hit by erosion. As a rule, Arctic regions are quite thinly populated. However, as nearly everywhere in the world, the coasts in the far north are important axes for economic and social life. The growing need for global energy resources as well as increasing tourism and freight（货运，运费） transport additionally intensify anthropogenic（报酬的） influence on the coastal regions of the Arctic. For wild animal stocks, like the great caribou（北美驯鹿） herds of the north, and the widespread freshwater lakes near the coast progressive erosion brings about significant changes in ecological conditions.

Brazilians are world leaders in using biofuels for gasoline（汽油） . About a quarter of their automobile fuel consumption comes from sugarcane, which significantly reduces carbon dioxide emissions that otherwise would be emitted from using gasoline. Now scientists from the Carnegie Institution’s Department of Global Ecology have found that sugarcane has a double benefit. Expansion of the crop in areas previously occupied by other Brazilian crops cools the local climate. It does so by reflecting sunlight back into space and by lowering the temperature of the surrounding air as the plants “exhale（呼气） ” cooler water. The study is published in the 2nd issue of Nature Climate Change, posted on-line April 17. The research team, led by Carnegie’s Scott Loarie, is the first to quantify the direct effects on the climate from sugarcane expansion in areas of existing crop and pastureland of the cerrado, in central Brazil.The researchers used data from hundreds of satellite images over 733,000 square miles— an area larger than the state of Alaska. They measured temperature, reflectivity (also called albedo), and evapotranspiration— the water loss from the soil and from plants as they exhale water vapor.As Loarie explained: “We found that shifting from natural vegetation to crops or pasture results in local warming because the plants give off less beneficial water. But the bamboo-like sugarcane is more reflective and gives off more water— much like the natural vegetation. It’s a potential win-win for the climate— using sugarcane to power vehicles reduces carbon emissions, while growing it lowers the local air temperature.”The scientists found that converting from natural vegetation to crop/pasture on average warmed the cerrado by 2.79 °F (1.55 °C), but that subsequent conversion to sugarcane, on average, cooled the surrounding air by 1.67 °F (0.93°C).The researchers emphasize that the beneficial effects are contingent（因环境而异的） on the fact sugarcane is grown on areas previously occupied by crops or pastureland, and not in areas converted from natural vegetation. It is also important that other crops and pastureland do not move to natural vegetation areas, which would contribute to deforestation.So far most of the thinking about ecosystem effects on climate considers only impacts from greenhouse gas emissions. But according to coauthor Greg Asner, “It’s becoming increasingly clear that direct climate effects on local climate from land-use decisions constitute significant impacts that need to be considered core elements of human-caused climate change.”

Could veterans of war, rape victims and other people who have seen horrific crimes someday have the traumatic memories that haunt them weakened in their brains? In a new study, UCLA life scientists report a discovery that may make the reduction of such memories a reality. “I think we will be able to alter memories someday to reduce the trauma from our brains,” said the study’s senior author, David Glanzman, a UCLA professor of integrative biology and physiology and of neurobiology（神经生物学） .The study appears in the April 27 issue of the Journal of Neuroscience, a premier neuroscience journal.Glanzman, a cellular neuroscientist, and his colleagues report that they have eliminated, or at least substantially weakened, a long-term memory in both the marine snail known as Aplysia and neurons in a Petri dish. The researchers say they gaining important insights into the cell biology of long-term memory.They discovered that the long-term memory for sensitization in the marine snail can be erased by inhibiting the activity of a specific protein kinase — a class of molecules that modifies proteins by chemically adding to them a phosphate (an inorganic chemical), which changes the proteins’ structure and activity. The protein kinase is called PKM (protein kinase M), a member of the class known as protein kinase C (PKC), which is associated with memory.The research has important potential implications for the treatment of post-traumatic stress disorder, as well as drug addiction, in which memory plays an important role, and perhaps Alzheimer’s disease and other long-term memory disorders.”Almost all the processes that are involved in memory in the snail also have been shown to be involved in memory in the brains of mammals,” said Glanzman, who added that the human brain is far too complicated to study directly.PKM is rare in that while most protein kinases（蛋白激酶） have both a catalytic domain, which is the part of the molecule that does its work, and a regulatory domain, akin to an on–off switch that can be used by other signaling pathways to shut off the activity of the kinase, PKM has only the catalytic domain — not the regulatory domain.”This means that once PKM is formed, there is no way to shut it off,” said Glanzman, who is a member of UCLA’s Brain Research Institute. “Once it is activated, PKM’s continual activity maintains a memory until PKM degrades.”Glanzman decided to study PKM in the marine snail, which has simple forms of learning and a simple nervous system, so that he could understand in precise detail how PKM’s activity maintains a long-term memory, a process that is not well understood.Glanzman and his colleagues — researchers Diancai Cai, lead author of the study; Kaycey Pearce; and Shanping Chen, all of whom work in his laboratory — studied a simple kind of memory called sensitization. If marine snails are attacked by a predator, the attack heightens their sensitivity to environmental stimuli — a “fundamental form of learning that is necessary for survival and is very robust in the marine snail,” Glanzman said.

Active efforts are required to preserve biodiversity in the seas – that far most people are in agreement. But in our enthusiasm to save uncommon species, we sometimes miss the common species that form the basis（根本，底部） of marine ecosystems. ‘Change strategy’ is the challenge to the authorities from researchers at the University of Gothenburg, Sweden. An inconceivably（不成思议地） large proportion of the animals that live in the seas are so uncommon that it is difficult to find more than a few specimens. Committing most resources to saving individual species is not just an expensive business – it would also risk destroying the foundation for ecosystems, the research of Professor Kerstin Johannesson shows.Her research team is able to demonstrate that it is the common species that are of really great significance for ecosystems, by establishing habitats for other species. It is therefore in all probability the most common species that determine the future of all species. If the common species disappear, it will have great consequences.An alarming example of what can happen is that the cod populations in the fjords（海湾，峡湾） of the Bohuslän coast have almost without exception disappeared. These fjords have consequently lost one of their most important species. It can have far-reaching consequences for several other species when the environments of the shallow bays change.”Without the big predatory fish, the sea-grass meadows become clogged, with the result that the shallow bays no longer act as larders and nurseries for inshore（近海岸的） fish. While life slowly dies out, the blame is put on eutrophication.”Kerstin Johannesson’s research is concerned with how different populations within one species may be so genetically different that they actually do not have very much to do with each other, and that in particular they are not interchangeable. If a local population disappears, it will not automatically be replaced by individuals from another population migrating in. In the worst case, even individuals of the other population are unable to cope in the environment of the extinct population.”That’s how it is with the cod populations in Bohuslän. Despite tough restrictions on catches and despite North Sea cod visiting the Bohuslän fjords every year, we are not getting the cod populations back. A similar example is the cod off the coast of Newfoundland in Canada, which have not returned despite a complete halt to fishing for nearly 20 years.”Focusing on the species in order to preserve species diversity in the seas is therefore an incorrect approach that may instead lead to greater losses. Despite this, there is a lack of legislation and recommendations today on how genetic variation within species should to be managed.

In a paper published in the April 25 early online edition of the Proceedings of the National Academy of Sciences, researchers at the University of California, San Diego School of Medicine, the Gladstone Institutes in San Francisco and colleagues report a game-changing advance in stem cell science: the creation of long-term, self-renewing, primitive neural precursor cells from human embryonic stem cells (hESCs) that can be directed to become many types of neuron without increased risk of tumor formation. “It’s a big step forward,” said Kang Zhang, MD, PhD, professor of ophthalmology and human genetics at Shiley Eye Center and director of the Institute for Genomic Medicine, both at UC San Diego. “It means we can generate stable, renewable neural stem cells or downstream products quickly, in great quantities and in a clinical grade – millions in less than a week – that can be used for clinical trials and, eventually, for clinical treatments. Until now, that has not been possible.”Human embryonic stem cells hold great promise in regenerative medicine due to their ability to become any kind of cell needed to repair and restore damaged tissues. But the potential of hESCs has been constrained（差遣，逼迫） by a number of practical problems, not least among them the difficulty of growing sufficient quantities of stable, usable cells and the risk that some of these cells might form tumors.To produce the neural stem cells, Zhang, with co-senior author Sheng Ding, PhD, a former professor of chemistry at The Scripps Research Institute and now at the Gladstone Institutes, and colleagues added small molecules in a chemically defined culture condition that induces hESCs to become primitive neural precursor cells, but then halts the further differentiation process.”And because it doesn’t use any gene transfer technologies or exogenous（外因的） cell products, there’s minimal risk of introducing mutations or outside contamination,” Zhang said. Assays of these neural precursor cells found no evidence of tumor formation when introduced into laboratory mice.By adding other chemicals, the scientists are able to then direct the precursor cells to differentiate into different types of mature neurons, “which means you can explore potential clinical applications for a wide range of neurodegenerative（神经变性的） diseases,” said Zhang. “You can generate neurons for specific conditions like amyotrophic lateral sclerosis (ALS or Lou Gehrig’s disease), Parkinson’s disease or, in the case of my particular research area, eye-specific neurons that are lost in macular degeneration, retinitis pigmentosa（色生性视网膜炎） or glaucoma（青光眼） .”The new process promises to have broad applications in stem cell research. The same method can be used to push induce pluripotent stem cells (stem cells artificially derived from adult, differentiated mature cells) to become neural stem cells, Zhang said. “And in principle, by altering the combination of small molecules, you may be able to create other types of stem cells capable of becoming heart, pancreas, or muscle cells, to name a few.”The next step, according to Zhang, is to use these stem cells to treat different types of neurodegenerative diseases, such as macular degeneration or glaucoma in animal models.

Latest insights into immunity to HIV could help to develop a vaccine to build antibodies’ defences against the disease, a University of Melbourne, Australia study has found. By investigating the action of the human antibodies called ADCC, in people with HIV, researchers were able to identify that the virus evolves to evade or ‘escape’ the antibodies.Professor Stephen Kent of the University of Melbourne and one of the senior authors on the paper said ADCC antibodies have been strongly implicated in protection from HIV in several vaccine trials but their action was poorly understood.”These results show what a slippery customer the HIV virus is, but also shows that these ADCC antibodies are really forcing the virus into changing, in ways that cause it to be weaker,” he said.”It also implies that if good ADCC antibodies were available prior to infection, via a vaccine, we might be able to stop the virus taking hold. This is the holy grail.”The group at the University of Melbourne’s Department of Microbiology and Immunology analysed blood samples of people with HIV and found their virus had evolved to evade or ‘escape’ the ADCC antibodies against HIV they are making to try to control their virus.The team led by Dr Ivan Stratov and Professor Kent employed a novel technology developed in their laboratory to find where ADCC antibodies were attacking the virus. They then looked at how the sequence of the virus had mutated over time to avoid the immune response.”There is an urgent need to identify effective immunity to HIV and our studies suggest ADCC responses supply significant immune pressure on the virus,” Dr Ivan Stratov, a clinician and researcher said.The group is now working on designing HIV vaccines to induce ADCC antibodies that make it more difficult for the virus to escape.The work was published in the prestigious international journal PNAS（美国科学院院报）.