Propellant Sneeze: How Far Does Your Sneeze Travel?

When a person coughs or sneezes, you can see the droplets. However, you do not see the gas clouds associated with coughs and sneezes. This invisible gas phase helps extend the distance of the individual droplets, particularly the small ones. A recent study has shown that coughs and sneezes have associated gas clouds that keep their potentially infectious droplets aloft over much greater distances than previously anticipated.

Researchers at the Massachusetts Institute of Technology (MIT) used high-speed imaging as well as laboratory simulations and mathematical modelling to analyse coughs and sneezes in terms of fluid-mechanics. The results suggest that smaller droplets travel further than larger ones which researchers previously assumed to be reversed as larger droplets tend to have more momentum. This would be true if each droplet were unconnected. However, the gas cloud emitted with a cough or sneeze tend to cause the smaller droplets to be swept around and resuspended, causing them to settle more slowly and travel further. Essentially, the smaller droplets can be carried a greater distance by the gas cloud while the larger droplets fall out.

The study showed that droplets 100 micrometers in diameter travelled five times farther than previously estimated, while droplets 10 micrometers in diameter travelled 200 times farther. The tendency of these droplets from coughs or sneezes, referred to as a ''multiphase turbulent buoyant cloud'', to remain airborne means that ventilation systems may be more prone to transmitting potentially infectious particles than previously suspected.

So, the next time you feel a cough or sneeze coming on, raise your elbows to cover up and warn people to take cover from the multiphase turbulent buoyant cloud you're about to expel.

Dark Chocolate to Fight Obesity and Type-2 Diabetes?

Dark chocolate has recently been associated with health benefits. From increasing satiety to lowering blood pressure, ingredients of chocolate have been shown to have a positive impact on health and the potential health benefits continue to pile up. Researchers have now found a particular ingredient that may even help prevent obesity as well as type-2 diabetes.

Cocoa, the main ingredient in chocolate, is rich in flavanols. Flavanols, a type of antioxidant found in grapes and tea, have been reported to aid weight loss and prevent type-2 diabetes. However, flavanols exist in different forms. Cocoa contains several different kinds of these compounds.

Groups of mice were fed different diets, including high-fat and low-fat diets, and high-fat diets supplemented with different kinds of flavanols. Researchers found that adding one particular set of these compounds, known as oligomeric procyanidins (PCs), to the food made the biggest difference in keeping the mice's weight down if they were on high-fat diets. It also improved glucose tolerance, which could potentially help prevent type-2 diabetes.

ORIGINAL RESEARCH: Effect of Interactive behaviour on blood glucose changes following a Carbohydrate load

Objectives: Benefits of physical activity on maintenance of blood glucose within an acceptable range are well documented. This study explores the possible beneficial effect of animated conversation and mental activities on blood glucose levels following dietary carbohydrate loading.

Design and Participants: Blood glucose changes were examined in 18 non-diabetic individuals following the consumption of two doughnuts providing ~48g of carbohydrate. The participants acted as their own controls and were studied twice. On the first occasion they maintained quiet/passive behaviour, on the second they conversed and participated in structured mental activities e.g. reading and solving puzzles.

Measurements: Using the Freestyle Freedom Lite glucose metre, baseline, then post-fasting blood glucose concentrations were evaluated every 30 minutes over a 2 hour period after the consumption of doughnuts.

Results: ANOVA repeated measures analysis of the results showed that time (P<0.001), activity (P<0.01) and time*activity interaction (P<0.05) all had a significant effect on the blood glucose levels. Compared with active intervention, the mean blood glucose levels during quiet/passive behaviour period remained ~30-40% higher and this difference was most significant at 30 minutes (1.40 vs 0.87 mmol/L, P<0.05)) and 60 minutes (1.53 vs 0.91mmol/L, P<0.01) measurements.

Conclusion: The results of this preliminary study indicate that simple non-exercise related activities involving mental activity and conversation have a significant influence on reducing blood glucose levels. This may be of value when individuals are unable to engage in regular exercise due to personal and environmental constraints.

Do extracts of tomato suppress an overactive bladder phenotype?

BACKGROUND Overactive bladder (OAB) is a symptomatic disease characterised by increased bladder voiding, urinary urgency and can be with or without urinary incontinence. Prevalence increases with age and affects both men and women equally. OAB causes a severe impact on the quality of life and the cause remains unknown. The current mainstay treatment is anti-muscarinic drugs. They offer relief in some patients but have a number of side effects.

Anecdotal evidence suggests lycopene and β carotene, both found in tomatoes, can improve lower urinary tract symptoms. Tomatoes, due to their high acid content, are also recommended to be avoided in OAB.

OBJECTIVE To determine whether extracts found in tomatoes can suppress an OAB phenotype.

MATERIALS AND METHODS Isometric tension experiments to measure the effect of lycopene, β carotene and ascorbic acid on an OAB phenotype induced using carbachol. Different concentrations of each agent were tested.

RESULTS Lycopene reduced spontaneous contractions and induced a periodic relaxation. The effect was concentration dependent. Lycopene caused a reduction in basal tone and amplitude of spontaneous contractions. There was a statistically significant reduction with 6µM but not with 12µM.

Ascorbic acid had no significant effect on spontaneous contractions with increasing concentration.

β carotene caused a small change in spontaneous contractions. The effect was similar in the vehicle control in which β carotene was dissolved in.

CONCLUSIONS Lycopene causes a concentration-dependent relaxation and a reduction in spontaneous contractions. Ascorbic acid has little to no effect on spontaneous contractions. The effect of β carotene needs to be further explored.

Sleep deprivation associated with food desire and food purchasing

Sleep deprivation significantly decreases activity in appetitive evaluation regions within the human brain and increases food purchasing the next day.

Sleep deprivation has been shown to reduce activity in appetitive evaluation regions within the human frontal cortex and insular cortex during food desirability choices. Functional magnetic resonance imaging (fMRI) was used to scan the brain of 23 healthy volunteers following both a normal night's sleep and a sleepless night. Activity in the frontal lobe, the region responsible for complex decision making, was impaired in the sleep-deprived brain while increased activity was observed in deeper brain centers which respond to rewards. Participants desired more high-calorie foods when they were sleep deprived. The findings suggest a brain mechanism by which sleep deprivation may influence the development of obesity.

Acute sleep deprivation has also been reported to increase food purchasing the following day. Sleep deprivation was associated with an increase in plasma ghrelin concentrations, a hormone responsible for increasing hunger, in 14 healthy volunteers. Sleep deprived individuals purchased significantly more calories and grams of food than they did after one night of sleep. The study suggests that acute sleep loss may influence food purchasing behavior.

Intelligent Eating Eggs: Science, Fiction, Or Yolklore?

It has previously been reported that omega-3 fatty acids lower the risk of cardiovascular disease, reduce triglyceride levels and lower blood pressure as well as delay the onset of dementia.

The effects of dietary intervention using eggs enriched with omega-3 fatty acids on plasma lipid concentrations, blood pressure and memory recall were determined in 8 healthy adult male and female participants.

Volunteers consumed three standard eggs per day in addition to their normal diet for the first 7 day test period followed by a 7 day washout period. The same group of volunteers then consumed three omega-3 eggs per day in addition to their normal diet for a further 7 day test period. Measurements were taken at baseline and periodically up to 11 days following commencement of each dietary regime.

Results analysis determined that mean plasma total cholesterol and LDL-cholesterol concentration was significantly increased by consumption of standard eggs (P<0.05) but significantly reduced (P<0.05) by consumption of omega-3 enriched eggs. Mean HDL-cholesterol concentration was unchanged by standard eggs but decreased significantly (P<0.05) by omega-3 eggs. No significant effect on plasma triglycerides was observed with consumption of either type of egg.

Both systolic and diastolic pressure was unchanged by intervention with either egg regime. There was a slight increase in memory recall test scores following consumption of both standard and omega-3 eggs. The increase however, was not statistically significant (P>0.05).

Inclusion of dietary omega-3 eggs may offer some health benefits, however the decrease in HDL cholesterol observed suggests the effects may also be detrimental to health.

Introducing disease-blocking bacteria into mosquitoes

A new technique of introducing a disease-blocking bacteria into mosquitoes has been announced.

Diseases such as dengue fever, yellow fever and malaria, all spread by mosquitoes, may be prevented by the introduction of the disease-blocking bacteria Wolbachia, into the mosquito.

When mosquitoes are infected with the strain of bacteria called wMelPop, they are unable to transmit viruses such as dengue fever which currently has no vaccination and is responsible for up to 40 000 deaths each year. It is difficult however, for the bacteria to spread among the mosquito population as it significantly reduces the ability of the mosquito to lay viable eggs. A suggested method to speed up the transmission of the bacteria involves introducing an insecticide resistance gene alongside Wolbachia into the mosquito. As insecticides are common in malaria and dengue-prone areas, this approach would allow survival of only Wolbachia infected mosquitoes and therefore prevent the transmission of viruses to humans.

This could be a major step forward in the disease control programme with a reduced rate of spread due to less infected mosquitoes.