Monthly Archives: September 2009

Adolescent alcohol abuse can lead to poor decision-making and greater risk-taking in adulthood*

(*Binge-drinking teenage tearaway rats make bad decisions in adulthood)

Experiments in rats show that alcohol abuse in adolescence affected the animal’s decision-making in adulthood, leading them to make poorer decisions and take more risks, according to research by Bernstein and colleagues from the University of Washington and published online on the 21st September in the journal PNAS.

Alcohol abuse, and in particular teenage binge-drinking, is becoming a serious and chronic health epidemic. Cheap alcohol is readily available and we don’t know the long term consequences from alcohol abuse at an early age. The European School Survey Project on Alcohol and others Drugs (ESPAD) is an extensive international study looking at teenagers’ drinking, smoking and drug-taking in 32 countries across Europe. Results from the 2007 survey ranked the UK 3rd in the binge-drinking European league; there were higher than average scores in variables including alcohol use and drunkenness in the last 12 months (88% of teenagers had consumed alcohol and 57% had been drunk in the same period) and the estimated alcohol consumption from the latest drinking day (6.2 cl alc. 100%, much higher than the European average of 4.2). Previous studies in humans have shown that young binge-drinkers had impairments in decision-making and that excessive alcohol intake may have an affect on the development of a young brain. There are somewhat obvious ethical issues in getting kids drunk and seeing what the long-term effects are so researchers used rats to investigate the direct link between alcohol consumption in adolescence and decision making as an adult.

The researchers fed adolescent rats a tasty gel containing 10% alcohol, or a control alcohol-free gel, for

binge-drinking rat

binge-drinking rat

20 days. In adulthood, either 3 weeks or 3 months after alcohol exposure, the rats were trained on a food reward task to measure their decision-making abilities. They were offered the choice of two levers; one gave a small but guaranteed reward of two treats, the other gave a larger, but uncertain, reward of four treats occurring 75%, 50% or 25% of the time. The control teetotal rats chose the small but more consistent rewards whilst the rat binge-drinkers were significantly more likely to make riskier choices and pick the larger but uncertain reward under all conditions.

These findings provide evidence that alcohol abuse in adolescence can lead to impaired decision-making as an adult. Furthermore, these effects persisted for at least 3 months after alcohol exposure. The model can be used in future experiments to understand just how alcohol exposure during adolescence affects the brain. This research suggests that alcohol abuse in adolescence could permanently change the way the brain works and that strategies to prevent teenage binge-drinking should be promoted.

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Scientists reveal genome sequence for the Irish potato famine pathogen

potato blight Nature coverThe genome of the potato blight mould (Phytophthora infestans) has been successfully sequenced in an international collaboration between scientists. The work, published in Nature last week, also reveals how the potato pathogen has adapted to cause disease.

Phytophthora infestans is a water mould (or oomycete) and the destructive pathogen that causes potato blight (or late blight). Oomycetes are microscopic organisms that form long filaments that look like, but are evolutionarily distinct from, fungi. P. infestans is infamous in human history as the culprit behind the Irish potato famine between 1845 and 1852. 1 million people died in Ireland (reducing the population by 20 – 25%) and 1 million more emigrated as a consequence of the famine. P. infestans is still a significant worldwide agricultural problem; potatoes are the 4th largest agricultural crop and crop losses as a result of potato blight are estimated to cost $6.7 billion. This potato pathogen is incredibly difficult to manage as it can rapidly adapt to control strategies, such as genetically engineering blight resistant potatoes, and still cause disease that rots the leaves and tubers of the potato plant.

The P. infestans genome is the biggest genome, at 240 megabases (Mb), sequenced so far in the chromalveolates (a eukaryote super group that contains water moulds and algae). Interestingly, the genome is so big because it is full of repetitive DNA, which makes up 74% of the genome. This includes a large number of transposons (so called “jumping genes”, DNA sequences that can move around to different positions within the genome). The P. infestans genome was compared to two related genomes, P. sojae (the cause of soy bean root rot) and P. ramorum (the cause of sudden oak death). This revealed that Phytophthora genomes have an unusual organisation; blocks densely packed with conserved (i.e. identical) genes between the genomes, which are separated by regions with high numbers of repeated DNA with few genes present. Interestingly, rapidly evolving virulence genes (which are induced during infection and allow the organism to colonise the potato plant) are present in these gene-sparse areas in P. infestans.

Highly dynamic regions of the Phytophthora genome may be crucial for its rapid adaptability to host plants and how it has evolved as a plant pathogen. The full genome sequence of P. infestans allows scientists to identify essential genes that allow the pathogen to destroy potato crops. This could help researchers devise new ways to protect potato plants from P. infestans, such as breeding new types of resistant potato plants or developing new (hopefully environmentally-friendly) chemicals to kill the potato pathogen.

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Researchers make first steps towards making a vaccine for urinary tract infections

utiFed up of stocking up on cranberry juice to stave off painful peeing….well researchers from the University of Michigan have made an important step towards making a vaccine to prevent urinary tract infections (UTIs), if the immunity seen in mice can be reproduced in humans. The findings by Alteri and colleagues were published this week in PLoS Pathogens (its open-access so go take a look at the paper for yourself).

UTI is a bacterial infection that affects any part of the urinary tract (including kidneys, ureter, bladder and urethra). They are incredibly common; it is thought 53% of women and 14% of men will experience a UTI during their lifetime. They are significant healthcare burden; in the United States alone, UTIs have an estimated annual cost of $2.4 billion each year. There are two types of UTI. Lower UTIs affect the bladder (cystitis) and urethra (urethritis) with symptoms of a mild fever, the urge to urinate frequently, smelly, bloody or cloudy urine, and that oh so infamous pain or burning sensation when you need to urinate. Upper UTIs affect the ureter and the kidneys (pyelonephritis) and include symptoms of high fever, nausea and vomiting, chills and shaking and localised pain in your lower back. Upper UTIs are potentially more serious since they can cause kidney damage. UTIs can be treated with antibiotics but there is increasing evidence of antibiotic resistance. Furthermore, recurrent infections occur frequently. An estimated 27% of women experience a second infection, and 2.7% of those suffer a third infection, within 6 months from the initial infection. Uropathogenic (pathogens that infect the urinary tract) Escherichia coli (UPEC) is the most likely cause of an uncomplicated UTI and so the researchers wanted to develop a vaccine to prevent infection by these bacteria.

The researchers used large-scale reverse vaccinology (pioneered by Rino Rappuoli and first used for vaccines against meningococci, the bacteria that cause meningitis). This combines bioinformatics, genomics and proteomics, to quickly and efficiently identify proteins in UPEC that are novel vaccine targets. The researchers looked for proteins to act as antigens, substances that would trigger an immune response to produce protective antibodies (a protein which binds foreign antigens to identify and neutralise them). The researchers screened 5,379 predicted bacterial proteins in the UPEC strain E. coli CFT073 and identified six proteins that matched vaccine candidate criteria including proteins that were highly expressed in vivo, specific to pathogens and induced during growth in human urine. The vaccine candidates were all pathogen-associated iron receptors (ChuA, Hma, Iha, IreA, IroN and IutA). These receptors are required for uptake of iron and are present on the surface of the bacteria. Each of the iron receptor proteins were expressed and purified and these antigens were cross-linked to cholera toxin, which acts as an adjuvant (a substance that increases the ability of an antigen to stimulate the immune system). Mice were inoculated with each antigen-adjuvant complex in their nasal passage. The researchers investigated whether mice could be protected from UTI and measured the immune response that occurred in the mice after vaccination.

Vaccination with Hma, IreA and IutA significantly protected mice against colonisation with UPEC strains in the kidneys and bladder. Spleen cells from vaccinated mice significantly secreted IFNγ and IL-17, which are protective proinflammatory cytokines (proteins released by cells which act as signalling molecules and help generate an immune response). Also, mice secrete protective antigen-specific antibodies following vaccination, which correlated with protection against infection with UPEC. Increased levels of IgA (an antibody found in mucous) were measured in urine and high levels of IgM (an antibody part of the primary immune response to a foreign antigen) and IgG (an antibody that is part of the secondary protective immune response) were measured in serum.

Vaccination with iron receptors elicits protective immunity from experimental UTI in mice. Iron receptors are promising vaccine candidates to protect against UPEC infections in humans and future clinical trials will determine whether the immunity seen here can be reproduced in humans. Interestingly, uptake of iron is a critical function required specifically by pathogenic bacteria in order to survive, but often not in commensal bacteria (normally harmless bacteria which are part of our natural microflora on and inside our bodies). Vaccines that include iron receptors could be used to prevent infections by other pathogenic bacteria. Also, the researchers show that vaccination in nasal mucous membranes induces an immune response in mucosal tissue elsewhere in the body, in this case the urinary tract. Although a successful UTI vaccine may be a long way off this paper details key research which should help its development.


Both these webpages give detailed info on symptoms, diagnosis and treatment of UTIs:

Medline Plus topic page on UTIs

http://www.nlm.nih.gov/medlineplus/urinarytractinfections.html

NHS direct topic page on UTIs

http://www.nhs.uk/conditions/Urinary-tract-infection-adults/Pages/Introduction.aspx

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Filed under Infectious Disease, Microbiology, Vaccine

Guts and gas galore inside nature’s giants

This might be the best programme that has been on TV. Ever. Yes, yes we all know The Wire is amazing but did The Wire have someone literally scrabbling around in the innards of a whale? Thought not.

Inside Nature’s Giants, screened on C4 in July 2009, was an amazing natural history programme describing the anatomy and inner workings of the largest animals on earth; an elephant, a crocodile, a whale and a giraffe. Hosted by veterinary surgeon Mark Evans, aided by the very enthusiastic comparative anatomist Dr. Joy Reidenberg (she’s the one that gets, literally, knee-deep in whale bits), and with gleeful comments on evolution by Richard Dawkins. This was a jaw-dropping documentary on how these animals have evolved and how each part of the animal works.

OK it is full of gore..…and gas (dead animals give off one hell of a fug), but the programme had me hooked for a whole month; mixing straight up science with expert enthusiasm and all for our televisual entertainment.

It might not be to everyone’s taste but if you’ve ever mused on how giraffes live with such long necks (and how they fight each other with them!!!) or just how big an elephant’s intestines are….then this is the programme for you (a surreptitious google and you’ll find it in no time on the inter-web). Plus, you get to enlighten your friends and family with all manner of “did you know…” anecdotes. I did anyway! Go on. Watch it.

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Psycho doesn’t lurk in your shower…….bacteria do

Our daily shower doesn’t just contain water; we can also get a face full of bacteria too. Shower heads can expose people to microbes, including potentially harmful pathogens according to research published this week by Pace (from the University of Colorado at Boulder) and colleagues.

Microbes (like bacteria, fungi and viruses) are everywhere and we humans interact with them on a daily basis. Most of the time, these microbes are harmless but sometimes they can cause disease. Shower heads are dark, warm and moist and can be the perfect breeding ground for bacteria. Bacteria multiply and clump together to form a biofilm (a slimy layer of bacteria stuck together). Our daily shower sprays these bacteria in tiny droplets of water (aerosols) into the air. Bacterial aerosols can be inhaled deep into the lungs and can cause diseases like bronchitis and other lung infections. This is a particular problem in immunocompromised individuals (people with a weak immune system that cannot fight off infections well) who are susceptible to infections by opportunistic pathogens (pathogens that usually do not cause disease in healthy people).

Shower heads have been implicated as a source of disease-causing pathogens such as Legionella pneumophila (the bacteria that causes Legionnaire’s disease) and Mycobacterium avium (M. avium, which can cause symptoms ranging from a mild persistent cough in healthy people to a tuberculosis-like disease in the immunocompromised). However, very little is known about what bacteria are present in shower heads and how frequently they can occur. This study aimed to look at the different types of bacteria that can be found in shower heads across several cities in the United States.

The researchers took swabs from 45 shower heads in homes, apartment buildings and public places in several sites in the United States; including New York City, Denver, Southern Colorado and Tennessee. They also took samples of the water that flows through the shower head. It can be very difficult to isolate bacteria from the environment and then grow them in the laboratory so the researchers used molecular genetics techniques to identify the bacteria. Bacterial DNA was isolated from the shower head swabs and water samples. The DNA was then amplified using polymerase chain reaction (PCR) to make thousands of copies of a particular bacterial gene. This gene was then sequenced to reveal what bacteria are present in the samples. Additionally, the researchers analysed samples using a very sensitive PCR reaction called quantitative PCR to specifically detect a single species of bacteria, M. avium.

The researchers found many different species of bacteria (including Mycobacterium, Escherichia and Methylobacterium species) on the shower heads which varied across the different sites. Many of the bacteria identified were common bacteria that are normally found in soil and water and are present everywhere, such as Pseudomonas and Sphingomonas species. Interestingly, there were more Mycobacterium species found in shower heads than in the tap water. Shower heads contained levels of M. avium that were >100 times higher than in the tap water supply and 20% of shower heads in the study were found to contain M. avium. Interestingly, the more publicised L. pneumophila, the cause of Legionnaire’s disease, was rarely identified in the study.

There’s no need to panic the organisms found in this study are not harmful to healthy people. M. avium is a bacterium that is commonly found in soil so we can easily encounter it in other settings within our daily lives, not just showers. The presence of M. avium in shower heads is only a concern because shower heads could create aerosols of bacteria that can be easily breathed directly into our lungs. Don’t forget M. avium only causes a mild infection in healthy people, and most people don’t even get symptoms. More serious infections are only seen in people with already weakened immune systems such as those with AIDS or cystic fibrosis.  Also, M. avium was not isolated everywhere, it was only found in certain sites across New York and Denver.

Professor Pace recommends “avoiding showers” for those who are immunocompromised if you want to reduce your risk of exposure to bacterial aerosols. He also suggests replacing shower heads more regularly, especially with metal ones since plastic ones “load up” with bacteria more quickly.

Ultimately your shower isn’t likely to make you sick and this is just an interesting study that describes some of the bacteria we encounter in our everyday lives. It gives an insight into the ecology of certain environments within the home, in this case what lurks beneath your shower head.

This work was published on 14th September 2009 in the early edition of the journal PNAS (Proceedings of the National Academy of Sciences).

http://www.pnas.org/content/early/2009/09/11/0908446106.abstract?sid=32e6b07b-ed09-4c40-81dd-0637ebd99483

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Filed under Microbiology

Cut those carbon emissions

At the start of September the 10:10 campaign was launched to get people and organisations in Britain to pledge to cut their carbon emissions by 10% by 2010. The campaign is the brainchild of Franny Armstrong, director of the climate change film “The Age of Stupid”. It’s simple, easy and something we can all do to help tackle climate change rather than sit back, bury our heads in the sand and read J.G. Ballard for tips on a post-apocalyptic lifestyle.

Still unconvinced on the perils of a warmer earth? Don’t quite feel morally obliged to do something yet? Then watch this excellent and informative animation by Leo Murray…it’s time to “Wake Up, Freak Out – then get a grip”. Nuff said.

So here’s a few things we can all do to make ourselves mini eco-warriors:

Fly less, drive less, brave the local bus or train.

Move a bit more; cycle, walk, run, hop jump and skip if you want, from A to B.

Turn down that thermostat then pop on some more jumpers

Get smelly, well not strictly true but have a shower instead of a bath and only run the washing machine when its full.

Make do and mend; step away from the shiny new purchases and listen to that shopper’s guilt for once

Bye bye meat….go veggie at least once a week

Love those leftovers, don’t buy trolleyfuls of food if you’re not going to eat it

10% cut by 2010. Simples.

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Hello world!

Well hello, this is my first attempts at a blog so er…it’s gonna be a bit ropey to start with but am a fast learner. Honest. This blog is dedicated to my love of all things science. This is my attempt to make it easy to understand and dare I say it…interesting to all. So embrace your inner science geek and enjoy.

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