What the scientists are saying…
Gum disease linked to Alzheimer’s People who suffer from gum disease are more likely to develop Alzheimer’s, a new study has found. For the research, a team in Taiwan looked at a national health database to identify people with a form of gum disease called chronic periodontitis (CP), and then worked out how many had later been diagnosed with Alzheimer’s. When they compared the CP patients’ outcomes with those of a control sample, they found that having CP for ten years increased the risk of Alzheimer’s by 70%. Gum disease, and associated inflammation, has been linked to diabetes and heart disease; and earlier studies have suggested it may play a role in dementia, too. However, in the latest study, only one in 100 of the people with CP went on to develop Alzheimer’s, so the overall risk remained low. Moreover, the researchers could not discount the possibility that some of the patients may have neglected their oral hygiene because they were already in the early stages of dementia.
Eradicating fear in mice Scientists have found a way of wiping specific scary memories from the brains of mice, a breakthrough that could help pave the way for better treatments for post-traumatic shock in humans. For the research, a team from the University of California, Riverside, used mild electric shocks to make mice fearful of a highpitched sound. After a while, they were so scared of it they would freeze in terror when it was played, even if no shock was administered. The team observed that this process had led to a strengthening in the tone pathways that carry the sound to the amygdala, a part of the brain involved in emotional reactions and memories (as a control, they’d also played the mice a lowpitched sound with no associated shocks: those pathways were unchanged). This strengthening persisted even after the mice were played the sound often enough without the shock to stop fearing it – which might explain why, after a period, the fear reoccurred. But by using a technique called optogenetics to weaken the pathways, they were able to stop this happening. “It permanently erases the fear memory,” study leader Dr JunHyeong Cho told The Guardian. “We no longer see the relapse of fear.” It’s not clear, however, how these findings could ever be applied to human memories without encountering major ethical problems. That’s because optogenetics is a biological technique which involves genetically modifying cells in living tissue (typically neurons) to be light sensitive, and then using light to control the activities of the neurons thus modified.
A living test centre for cancer Cancer is complex to treat because everyone has their own type – which may or may not respond to particular treatments. Doctors sometimes try to refine the testing process by implanting an individual’s tumour into a mouse, and seeing how it responds to the drugs. However, tumours take a long time to grow in mice, and reaching a verdict can take two to six months. Now scientists think that zebrafish larvae could offer a more efficient alternative. Although these are less genetically similar to humans than mice, a small preliminary study, by a team in Lisbon, has suggested that they might work as living “test centres”, providing results in as little as two weeks.
The bacteria hotspot by the sink They are filthy, yet we use them to clean. Kitchen sponges are riddled with bacteria that flourish in warm, wet conditions, and a new study has laid bare just how serious the problem is. Rather than relying on cell cultures grown from samples, the German researchers used genetic sequencing to compile the most comprehensive list of sponge bacteria to date. Having analysed 14 sponges, they concluded that these contained 54 billion bacteria per cubic cm, (cm3) from 118 genera. Most of these were harmless... but not all. Among them were varieties of E.coli and salmonella. More disturbingly, the team also found that the usual methods for cleaning sponges aren’t effective: boiling and microwaving them only killed a few weaker bacteria, leaving more room for others to flourish. The best option may simply be to replace sponges weekly. However, the researchers also say that unless people are weakened by illness, a sponge is unlikely to do much harm.