Quick, can you describe your grandparents? Staphylococcus aureus, or the Golden Staph, can and it is a single cell. If you couldn’t you should visit them more often. In any case, a very cool paper came out recently but before we can get there we need to begin by going backwards to explain a very important bacterial structure called peptidoglycan.... Read more »
Turner, R., Ratcliffe, E., Wheeler, R., Golestanian, R., Hobbs, J., & Foster, S. (2010) Peptidoglycan architecture can specify division planes in Staphylococcus aureus. Nature Communications, 1(3), 1-9. DOI: 10.1038/ncomms1025
van Heijenoort J. (2001) Formation of the glycan chains in the synthesis of bacterial peptidoglycan. Glycobiology, 11(3). PMID: 11320055
There’s been a lot of buzz at recent conferences around a controversial new paper in J. Neurosci. from Ray and Maunsell on LFP traveling waves. It’s a pretty direct, and rather convincing rebuttal of an influential Nature Neuroscience paper by Nauhaus et al. published a couple of years ago. Initial findings Nauhaus found what seemed [...]... Read more »
Ray S, & Maunsell JH. (2011) Network Rhythms Influence the Relationship between Spike-Triggered Local Field Potential and Functional Connectivity. Journal of Neuroscience, 31(35), 12674-82. PMID: 21880928
Nauhaus I, Busse L, Carandini M, & Ringach DL. (2009) Stimulus contrast modulates functional connectivity in visual cortex. Nature neuroscience, 12(1), 70-6. PMID: 19029885
Recently, honey bee (Apis mellifera) populations in North America and in Europe have been experiencing increased annual losses due to a phenomenon known as Colony Collapse Disorder (CCD). Population loss of honey bee colonies poses grave risks to agriculture, due to the importance of these insects in pollination of food crops. Since the effect of environmental pathogens on bees has been poorly studied, the causes of CCD have not beeen well characterized. Thus, it is necessary to build a database of bee pathogens to learn more about pathogen transmission and to determine their role in CCD.
To this end, Runckel et al. wanted to identify what constitutes an abnormal pathophysiological condition in a honey bee colony. Using the Nextera™ DNA Sample Prep Kit (Illumina®-compatible), the researchers developed pools of sequence data from 20 different monitor hives in an ultra-deep sequencing experiment, and these data were compared to sequence data from known bee pathogen types, including known viruses, Nosema sp., Crithidia mellificae, and bacteria. The authors state that theirs is the first U.S. honey bee pathogen monitoring study to report both comprehensive pathogen incidence and relative abundance of specific pathogens over time. Results from their molecular analysis pipeline (microarray, PCR, qPCR, ultra-deep sequencing) identified four novel RNA viruses, and provide a basis for future epidemiologic studies aimed at determining the causes of CCD.
Runckel, C. et al. (2011). Temporal Analysis of the Honey Bee Microbiome Reveals Four Novel Viruses and Seasonal Prevalence of Known Viruses, Nosema, and Crithidia PLoS ONE, 6 (6) DOI: 10.1371/journal.pone.0020656
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Runckel, C. et al. (2011) Temporal Analysis of the Honey Bee Microbiome Reveals Four Novel Viruses and Seasonal Prevalence of Known Viruses, Nosema, and Crithidia. PLoS ONE, 6(6). DOI: 10.1371/journal.pone.0020656
Old World Psychotherapy: Sofa of Sigmund FreudThere has been a series of interesting research studies examining the effect of psychotherapy on brain structure and function. These studies have typically shown that effective psychotherapy results in reduction of brain deficits or abnormalities associated with a specific neuropsychiatric disorder.Now a study published in Plos One summarizes the results of study examining the use of real-time fMRI to provide neurofeedback during an amygdala activation task. This research was completed by neuroscientists affiliated with the Laureate Institute of Brain Research in Tulsa, Oklahoma and George Mason University in Fairfax, Virginia. (Disclosure: The author of Brain Posts is employed by Laureate Institute of Brain Research but was not involved in the study reviewed in this post.)The authors of this study noted the key role of the amygdala in the processing of emotions. They developed a experimental paradigm to train control subjects to increase the activation of the brain left amygdala. A group of young male subjects were instructed in a happy autobiographical memory task and provided real-time feedback on how successful they were in increasing blood flow to the left amygdala.Subjects identified three key happy memories from their past. During the experimental phase, they were instructed to recall these specific memories while being scanned using an fMRI scanner. They were provided real-time feedback on a monitor screen on the changes in left amygdala BOLD signal. (Subjects were told prior to scanning that fMRI neurofeedback is delayed by a few seconds due to the brain hemodynamic process).Subjects provided real-time feedback were more successful at increasing the left amygdala activation than those in a control group. This increase in the experimental group correlated with increases in other brain areas known to have functional connectivity with the amygdala (fronto-temporo-limbic network).New World Psychotherapy: Real Time fMRIAdditionally, the study identified six specific regions where functional connectivity identified correlations with the left amygdala activation:right medial frontal cortexbilateral dorsomedial prefrontal cortexleft anterior cingulate cortexbilateral superior frontal gyrusSubjects were selected based on being free of a history of neuropsychiatric disorders including anxiety and depression. However, there was some variability in the level of change in left amygdala activation with neurofeedback training. Subjects who scored high on the Difficulty Identifying Feelings scale had less increase in the left amygdala. Additionally, subjects with higher scores on a scale of being susceptible to anger showed less increase.This research is an very important advance in understanding the amygdala and regions connected with the amygdala. Additionally, it raises the possibility that real-time fMRI may emerge as a tool to understand processes associated with psychotherapy and to be an emerging model for providing therapy under real-time neurofeedback conditions. The site of psychotherapy might be moving from the sofa model of Sigmund Freud to the fMRI scanner. Both methods have subjects that lie down, but only the fMRI method provides real-time feedback of brain effects related to a psychotherapy intervention.The authors note that this study was a type of "proof-of-concept" study since it focused on healthy control subjects. They suggest that this type of model might be particularly relevant to cognitive behavioral treatment of conditions such as PTSD and major depression.Photo of Sigmund Freud sofa from the Freud Museum in London from Wikipedia distributed under the GNU Free Documentation License.Photo of Functional Magnetic Research Imaging device courtesy of the Laureate Institute for Brain Research. Zotev, V., Krueger, F., Phillips, R., Alvarez, R., Simmons, W., Bellgowan, P., Drevets, W., & Bodurka, J. (2011). Self-Regulation of Amygdala Activation Using Real-Time fMRI Neurofeedback PLoS ONE, 6 (9) DOI: 10.1371/journal.pone.0024522... Read more »
Zotev, V., Krueger, F., Phillips, R., Alvarez, R., Simmons, W., Bellgowan, P., Drevets, W., & Bodurka, J. (2011) Self-Regulation of Amygdala Activation Using Real-Time fMRI Neurofeedback. PLoS ONE, 6(9). DOI: 10.1371/journal.pone.0024522
There are many theories about why individuals engage in heavy alcohol consumption. One general theory psychologists refer to is called the Dual Process Model. It holds that people have two different systems for processing information. The impulsive system automatically (quickly) evaluates stimuli in the environment in terms of emotion, and motivation, and (again quickly) pushes the individual to move toward or away from the stimuli. Alternatively, the reflective system focuses on long-term goals and personal standards but it is slower acting and requires more effort or energy. These two systems constantly battle for supremacy. In the case of drinking, if the impulsive system wins out an individual will likely consume cocktail after cocktail because the drink tastes good, or makes the person feel good. If the reflective system wins out, the individual will likely consume less, or not at all, knowing that in the long-run they will be healthier and happier if they avoid such excess.
The ability of the reflective system to win out, or override automatic impulses and maintain goal-directed action, is accomplished by, what psychologists call, executive functioning. Executive functioning includes a host of different cognitive functions such as planning, attention control, working memory (the ability to maintain and manipulate information), and response inhibition (the ability to override impulsive responses). Unfortunately, research has shown that these executive functions are often impaired in chronic drinkers. First, individuals who start out with poorer executive functioning are more prone to become chronic drinkers if they associate alcohol with feeling good. Even more, excessive drinking has been shown to further impair executive functions. This means that the more one drinks the harder it will be for them to stop drinking.
Though this sounds pretty dire, there have been a host of recent studies showing that executive functions like working memory and response inhibition can be trained. That means with practice people can become better at tipping the scale in favor of their long-term goals (the reflective system), rather than their automatic temptations (the impulsive system). Researcher Katrijn Houben and colleagues at Maastricht University and the University of Amsterdam, tested whether training executive functions, specifically working memory, could boost the supremacy of the reflective system, and thus help heavy drinkers to consume less alcohol. Read More->... Read more »
Houben K, Wiers RW, & Jansen A. (2011) Getting a grip on drinking behavior: training working memory to reduce alcohol abuse. Psychological science, 22(7), 968-75. PMID: 21685380
A group of researchers from the IPHES (Institut Català de Paleoecologia Humana i Evolució Social) reports on the discovery of a handheld wooden implement from Mousterian deposits at Abric Romaní, Spain. The tool was found in Level P which dates to about 56,000 years BP, and its morphology suggests that it might have been a small spade/shovel, or perhaps a poker, given its association to a hearth... Read more »
CARBONELL, E., & CASTRO-CUREL, Z. (1992) Palaeolithic wooden artefacts from the Abric Romani (Capellades, Barcelona, Spain). Journal of Archaeological Science, 19(6), 707-719. DOI: 10.1016/0305-4403(92)90040-A
Castro-Curel, Z., & Carbonell, E. (1995) Wood Pseudomorphs From Level I at Abric Romani, Barcelona, Spain. Journal of Field Archaeology, 22(3), 376-384. DOI: 10.1179/009346995791974206
Vallverdú, J., Vaquero, M., Cáceres, I., Allué, E., Rosell, J., Saladié, P., Chacón, G., Ollé, A., Canals, A., Sala, R.... (2010) Sleeping Activity Area within the Site Structure of Archaic Human Groups. Current Anthropology, 51(1), 137-145. DOI: 10.1086/649499
It is well known that the modern world religions which trace their origins to the Axial Age are centrally concerned with death. Some might call this concern an obsession. Of these world religions, only Hinduism does not have Axial roots. This is not to say that “Hinduism” (which is neither singular nor unified) was unaffected [...]... Read more »
Blackburn, Stuart H. (1985) Death and Deification: Folk Cults in Hinduism. History of Religions, 24(3), 255-274. info:/
Never buy a car with a salvage title. Anyone who has ever driven a car after a major accident can tell you why—it’s just not the same as before the crash. Though all the parts might be in the right place and the paint just as shiny as before, there’s invariably some new rattle, shake, [...]... Read more »
Gibson, L., Lee, T., Koh, L., Brook, B., Gardner, T., Barlow, J., Peres, C., Bradshaw, C., Laurance, W., Lovejoy, T.... (2011) Primary forests are irreplaceable for sustaining tropical biodiversity. Nature. DOI: 10.1038/nature10425
After being side-tracked by my last B821: Financial Strategy assignment last week, and life in general, I’m back on the personal EBI case. Following on from Drucker’s ideas for managing oneself better, I turned to Herminia Ibarra for further guidance on framing my career-after-MBA direction. Ibarra and Lineback (2005) in their article “What’s your Story?” [...]... Read more »
It’s a common scenario. You’re at a wedding reception, the speeches are over, and a DJ starts up in the corner of the room, hidden behind a wall of flashing disco lights. Before long, the complimentary champagne begins to work its magic on the assembled crowd. A mildly inebriated Auntie Valerie is the first to wander [...]... Read more »
The history of penguins in Africa is a history of false starts. The first penguin pioneers that settled Africa millions of years ago all went extinct. But the penguins didn’t give up. They came back, swept there by ocean currents, and repopulated the African coasts. That’s what the palaeontologists Daniel Ksepka and Daniel Thomas conclude [...]
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Ksepka DT, & Thomas DB. (2011) Multiple cenozoic invasions of Africa by penguins (Aves, Sphenisciformes). Proceedings. Biological sciences / The Royal Society. PMID: 21900330
How many of you remember the first time you saw that phage image in your Bio 100 textbook? You know–the one that had the angular head, the coiled tube, and the spiky leg-looking things? That’s been burned into my memory banks ever since. And to find out that it was just a teeny packet of [...]... Read more »
Fiers, W., Contreras, R., Duerinck, F., Haegeman, G., Iserentant, D., Merregaert, J., Min Jou, W., Molemans, F., Raeymaekers, A., Van den Berghe, A.... (1976) Complete nucleotide sequence of bacteriophage MS2 RNA: primary and secondary structure of the replicase gene. Nature, 260(5551), 500-507. DOI: 10.1038/260500a0
Klucar, L., Stano, M., & Hajduk, M. (2009) phiSITE: database of gene regulation in bacteriophages. Nucleic Acids Research, 38(Database). DOI: 10.1093/nar/gkp911
Stano, M., & Klucar, L. (2011) phiGENOME: An integrative navigation throughout bacteriophage genomes. Genomics. DOI: 10.1016/j.ygeno.2011.07.004
Language is powerful. We’ve all seen it wielded to craft attitudes toward out-groups as the country becomes increasingly politically polarized. But here’s some research that shows how powerful language can be even when we are dissecting our own attitudes and perceptions of our individual behavior. Researchers talked to 171 stay-at-home moms about whether their decision to [...]
Related posts:Motherhood and Employment: Pregnancy Discrimination in the Workplace
Foot in mouth? Rate of speech, verb choice, and calling women “guys”
Power, Penises and the Role of the Presiding Juror
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Stephens, N., & Levine, C. (2011) Opting out or denying discrimination? How the framework of free choice in American society influences perceptions of gender equality. . Psychological Science. info:/
A tendency to view the world positively yields many benefits, such as higher wellbeing and a sense of personal effectiveness that gets you ahead in life. However, according to a recent article in the Journal of Occupational and Organizational Psychology, this sunny view of life brings with it certain workplace expectations – and when they aren't fulfilled, it can spell trouble. Behold the “disaffected pollyannas”.Researchers Olivia O'Neill, Laura Stanley, and Charles O'Reilly were interested in the career expectations and choices made by individuals with high “trait positive affect” (PA). They recruited 132 participants from a full-time MBA course, who sat an assessment centre where they completed a Positive and Negative Affect Scale and reported what they expected their highest lifetime salary to be. The data showed that PA results in confidence about salary, with every one-unit increase in PA associated with a $100,000 increase in expected earnings. High hopes, but what if they aren't met?Four years later, 105 of the participants responded to a follow-up survey probing salary levels and frequency of moving organisation. High PA individuals turned out to be far more responsive to low salary; at a standard deviation below average, they shifted through an average of four jobs, compared to two for their low-PA counterparts. This higher turnover was expected, as frustration of their higher salary expectations is more likely to lead to doubting their fit at the organisation. Moreover, they are more willing to believe the grass is greener elsewhere, and more able to make that step successfully, due to better social networks and an interview advantage due to infectious positive affect at interview (similar to the rapport advantage described here).Measures of job and life satisfaction at a final follow-up eight years on showed that for low PA individuals, more frequent job shifts led to more satisfaction. The notion is that shopping around means that over time you get a sense of what is realistic and make your peace with what a reasonable job constitutes. But for high PA, the reverse was true, with more job shifts making them more frustrated, bemoaning the absence of the perfect job they are destined for.High PA individuals can be a positive feature in organisations, but this research shows that they can be open to disappointment, affecting their prospects in the organisation and their feelings on life. The authors conclude that “the key to finding long-term satisfaction, then, may be managing expectations, rather than pursuing unrealistic ideals.”O'Neill, O., Stanley, L., & O'Reilly, C. (2011). Disaffected Pollyannas: The influence of positive affect on salary expectations, turnover, and long-term satisfaction Journal of Occupational and Organizational Psychology, 84 (3), 599-617 DOI: 10.1348/096317910X500801... Read more »
O'Neill, O., Stanley, L., & O'Reilly, C. (2011) Disaffected Pollyannas: The influence of positive affect on salary expectations, turnover, and long-term satisfaction. Journal of Occupational and Organizational Psychology, 84(3), 599-617. DOI: 10.1348/096317910X500801
It is some time I am not writing posts but the good reason is that I was in Leipzig to IRS 2011 Conference, a very interesting event in a beautiful city. It was inspiring to be in the city where Bach spent a great part of his life. Back to home, I checked as usual [...]... Read more »
Ph. Boucaud, J. P. Leroy, A. Le Yaouanc, J. Micheli, O. Péne, & J. Rodríguez-Quintero. (2011) The Infrared Behaviour of the Pure Yang-Mills Green Functions. arXiv. arXiv: 1109.1936v1
Marco Frasca. (2009) Exact solution of Dyson-Schwinger equations for a scalar field theory. arXiv. arXiv: 0909.2428v2
I. L. Bogolubsky, E. -M. Ilgenfritz, M. Müller-Preussker, & A. Sternbeck. (2009) Lattice gluodynamics computation of Landau-gauge Green's functions in the deep infrared. Phys.Lett.B676:69-73,2009. arXiv: 0901.0736v3
Credit: FLETCHER & BAYLIS/SCIENCE PHOTO LIBRARY
Out of the dense, tropical rainforest of Northern Vietnam, researchers have discovered a missing link in viral evolution. Through the large-scale screening of trapped mosquitoes, a joint Dutch and Japanese group may have identified the secrets of how one group of viruses - the nidoviruses - got really big.
This work potentially answers one of the more prevailing mysteries in viral evolution: how can RNA viruses escape the evolutionary restrictions placed on them by their very high mutation rates and get more complex? If you look closer though, more questions are thrown back than are answered.
The positive-sense RNA viruses are an extremely large and diverse group of viruses, housing many known - and unknown - human pathogens and indeed many non-pathogenic, environmentally influential microbes. On the whole, these viruses don't get very big (see the graph below); having a genome made of RNA isn't particularly a good thing if you want to have a long genome, encoding lots of complex genes. The enzymes these viruses use to copy their genomes are nowhere near as accurate as their cellular counterparts. And, introducing mutations every few thousands nucleotides is bound to impact on your evolutionary potential and fitness.
Distribution of +ve sense RNA virus genome sizes, notice the large gap between the nidoviruses and others. See the newly discovered virus, NDiV lying close to the lower limit.
But certain members of one group, the nidoviruses (containing the now infamous SARS-coronavirus) are somehow able to greatly expand their genomes and complexity taking the range of positive-sense RNA genome sizes from 3 kilobases (kb) to 31. The longer the genome you can have, the more genes and proteins you can encode. This thus increases the potential function and complexity of the virus which obviously plays a major role in host adaptation, evasion of immunity and pathogenesis.
The reasons just how the nidoviruses achieve comparatively massive size are subject to intense research and interest. Yet to make it all the more complex, the nidoviruses themselves bridge this genome size gap: some of them are 'small', with genomes around 13kb while some are 'large', with genomes around 30kb. Clearly, something is going on with these larger viruses that allows them to get around this apparent mutational block on genome size.
Using bioinformatic techniques, this capacity to achieve genome sizes of 30kb has been potentially mapped to one particular region of the 'larger' nidovirus genomes: a 3'-5' exoribonuclease found within the polymerase enzyme that facilitates the editing out of incorrect components of RNA and may allow for a decreased mutation rate. If you mess with this enzyme, you also screw up their replication accuracy, as documented here using deep-sequencing. And, as the theory goes, the lower this rate, the bigger the genomes can get. It is believed that this enzyme is a distant relative of cellular proteins, but how it arrived in the nidoviruses is anyones guess.
SARS-coronavirus genome structure and virus particle. This virus is a good model for the larger nidoviruses. The uncovered exoribonuclease is found within ORF1b.
This is where the mosquitoes come in, while searching for unknown human pathogens in Vietnamese jungles, the researchers found something they altogether didn't expect (grab the paper here). Although they found a new virus (named Nam Dinh virus after the province it was found in - NDiV), when sequenced, it was found to be a novel member of the nidoviruses and probably didn't cause any disease in humans. But strangely - when examined more closely - it didn't fit into the pre-defined 'small' and 'large' groups: it's genome lay between the small and large groups of viruses at around 20kb. .
The team also determined that this virus encoded those enzymes previously thought to be specific to the large viruses, although it had a genome size much closer to the smaller ones. NDiV was found to be an ancestral lineage of current invertebrate nidoviruses, which themselves are on the small end of the scale. So what does this say about how these positive-sense RNA viruses got so big? And why is this study so important? Especially as just a few months ago, another insect nidovirus was discovered in Côte d'Ivoire, although its genome did not encode an exoribonuclease.
The discovery of the exonuclease enzyme - combined with it's genome size - in this newly discovered virus leads to its classification as a viral 'missing link' between the large and small nidoviruses. Yet, while it is closer in size to the smaller viruses, it does encode those enzymes that control mutation rate in the larger viruses, thus, if anything, this discovery expands the lower limit of 'large' nidoviruses. On the other hand, this may be taken as evidence that the exoribonuclease isn't ALWAYS responsible for large genome sizes. But the previously carried out biochemical work clearly shows that the enzyme is responsible for nidovirus replication fidelity.
These results are only the first, near-preliminary analysis of this virus and I suspect that a more detailed molecular study may be able to expand on the activity of the 'large' versus 'small' enzymes in nidovirus evolution.The other proteins from this virus will continue to interest researchers studying how these viruses got so big.
The 'Eigen Trap' hypothesis of factors influencing genome size, compexity and mutation rate. RNA viruses may escape all restrictions through the acquisition of the exoribonuclease enzyme.
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Nga, P., Parquet, M., Lauber, C., Parida, M., Nabeshima, T., Yu, F., Thuy, N., Inoue, S., Ito, T., Okamoto, K.... (2011) Discovery of the First Insect Nidovirus, a Missing Evolutionary Link in the Emergence of the Largest RNA Virus Genomes. PLoS Pathogens, 7(9). DOI: 10.1371/journal.ppat.1002215
I'm looking at you, marathoners and triathletes. While you're out there building superhuman endurance and making the rest of us feel bad, are you also beefing up your immune systems? Or does becoming an Ironwoman actually weaken your body's defenses?
It may depend on how you're exercising. Researchers in Taiwan compared two types of exercise, the names of which might reveal the researchers' own feelings toward hitting the gym: "Acute Severe Exercise" (ASE) and "Chronic Moderate Exercise" (CME). In medicine, "acute" is something that comes on quickly and is over soon, as opposed to a chronic illness. The flu, say, as opposed to mono.
The subjects were 13 males between the ages of 20 and 24. Though young and otherwise healthy, they weren't in shape; the subjects had been getting less than one hour a week of exercise for at least the past six months. At the beginning of the study, all 13 subjects underwent "acute" exercise, cycling at increasing levels of difficulty until they reached exhaustion.
Afterward, five subjects became controls. They were told to continue not exercising for the next four months. Twice during that period, they showed up for another bout of ASE, so researchers could make sure that their bodies and their exercise abilities were staying the same. Meanwhile, the other eight subjects began two months of "chronic" exercise. They worked out five days a week for 30 minutes. The moderate intensity of their workout was defined as a percentage of the work they'd been able to do during ASE. After two months, the exercisers were also instructed to stop exercising. They spent two more months getting no exercise at all. In each month of the study, they also did an ASE test so researchers could see how their bodies' response to severe exercise was changing.
Outwardly, the effect of consistent (excuse me, chronic) exercise on the bodies of formerly sedentary people was unsurprising. After two months of training, the CME subjects had lost weight, lowered their resting heart rates, and increased their endurance. Then they stopped exercising. After the two-month "detraining" period, subjects' weights and heart rates had returned to their original levels, though the work they could do in the ASE task was still elevated, showing a lasting effect on their fitness. The control subjects did their job well, staying the same during the four months.
But what the researchers were interested in was the inner changes in their subjects; namely, changes to white blood cells called neutrophils. These are key players in the immune system, responding to the site of infection in the body and attacking any invaders they find. Neutrophils are short-lived cells, committing cell suicide (called apoptosis) after only a few days in the bloodstream. If these white blood cells are too enthusiastic about offing themselves, it can weaken the immune system.
Neutrophil death may be linked to the abundance of oxygen-containing molecules that react with everything around them, harming structures inside the cell. Since extreme exercise can increase the amount of these harmful "reactive oxygen species" in the body's tissues, the researchers wanted to know how exercise affected neutrophils. They drew blood from their subjects periodically, both at rest and after their ASE trials, and removed the neutrophils for analysis.
They found that "acute severe exercise" did, in fact, accelerate neutrophil suicide. It also increased the amount of reactive, oxygen-containing molecules in the cells.
"Chronic moderate exercise," on the other hand, appeared to slow down the death of neutrophils. After two months of regular exercise, subjects' white blood cells were showing less oxidative stress and slower apoptosis. Even after subjects spent the following two months not exercising, the effect lingered.
In a final twist, the positive effects of consistent exercise seemed to counteract the harmful effects of extreme exercise. After the acute exercise task, subjects who'd been exercising regularly did not show the same damage to their neutrophils that they had at first. But after two sedentary months, the protective effect had begun to fade.
What does all this mean for the marathoner or the Ironwoman? Unfortunately, since the subjects were all men, the study says very little about women of any kind. But for the young, previously sedentary males involved, the study suggests that sudden, exhausting exercise accelerates the death of certain immune cells. Consistent and moderate exercise, on the other hand, prolongs these cells' lives. It also buffers the damaging effect of occasional extreme exercise. And when you stop exercising, the positive effects of your old routine linger, at least for a little while.
The researchers point to other studies that have shown a connection between sudden, extreme exercise and upper respiratory tract infections. In this study, we can't see the effect that various rates of neutrophil death had on subjects' immune systems as a whole. When neutrophil death was accelerated after acute exercise, were subjects truly more vulnerable to infection, or did the immune system compensate somehow for neutrophil loss? In subjects who got regular exercise and prolonged the lives of their neutrophils, was the immune system strengthened? Does keeping these short-lived cells alive for longer necessarily help prevent infection, or could it create a burden for the body?
Overall, the authors think the evidence is in favor of consistent and moderate exercise. For patients whose immune systems are impaired by HIV or chemotherapy, regular exercise might provide a boost. This study suggested that consistent exercise counteracts the negative effects of extreme exercise--at least some of the effects. But to stay on the safe side, the authors recommend that you avoid "acute severe exercise" like, well, the plague.
Syu, G., Chen, H., & Jen, C. (2011). Severe Exercise and Exercise Training Exert Opposite Effects on Human Neutrophil Apoptosis via Altering the Redox Status PLoS ONE, 6 (9) DOI: 10.1371/journal.pone.0024385
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Syu, G., Chen, H., & Jen, C. (2011) Severe Exercise and Exercise Training Exert Opposite Effects on Human Neutrophil Apoptosis via Altering the Redox Status. PLoS ONE, 6(9). DOI: 10.1371/journal.pone.0024385
The role of specific neurotransmitters and neurotransmitter circuits in decision making is being explored in a variety of ways. Dopamine appears to have significant research support for a key role in making decisions related to reward.The role of serotonin in decision making is less well studied but also appears to be important. Robert Rogers, Ph.D. recently presented some of his lab's research at the Warren Frontiers in Neuroscience lecture in Tulsa, Oklahoma. (Additionally, I have reviewed and placed a link to a recent research manuscript from Dr. Rogers related to topic below.)Dr. Rogers noted the relationship between serotonin, depression and social function include these research findings:Social isolation is a known risk factor for major depressionSerotonin appears important in developing nourishing social contactsSocial isolation found in anxiety and depression may be mediated by serotonin mechanismsSerotonin mechanisms in human research is aided by the safe ability to modulate brain serotonin levels. Brain serotonin can be temporarily depleted using a amino acid drink deficient in the serotonin precursor L-tryptophan. Humans without mood or anxiety disorders show an increase in brain serotonin after a week of administration of any of commonly used selective serotonin reuptake inhibitors.Depleting serotonin or augmenting serotonin can be combined with a variety of behavioral and brain imaging techniques. Dr. Rogers note his lab has recently documented several findings in adult control subjects without current or past anxiety or depression:Tryptophan depletion decreased measures of cooperative interaction in a resource management game known as the Prisoner's dilemmaTryptophan depletion appears to impair the ability of individuals to learn from a social cooperation taskWhen working on a resource decision task, trytophan depletion changed decision-making behavior in women but not in menThe antidepressant citalopram reversed the decision making behavior changes found in women with tryptophan depletionThe brain medial prefrontal cortex is activated when individual observe the social decision-making behavior of othersWhen working in groups on a resource harvesting task, tryptophan depletion produces a tendency to revert to the mean behavior in the group, even when this results in an earlier adverse group outcomeDr. Rogers notes that these findings support more research in clinical populations suffering from a mood or anxiety disorders. Serotonin dysregulation found in depression and other psychiatric disorders may go hand-in-hand with deficits in initiating social interaction, impaired learning from social interaction experience and making adverse decisions in social situations.Photo of Coopers Hawk from the author's private collection. Rogers RD (2011). The roles of dopamine and serotonin in decision making: evidence from pharmacological experiments in humans. Neuropsychopharmacology : official publication of the American College of Neuropsychopharmacology, 36 (1), 114-32 PMID: 20881944... Read more »
Rogers RD. (2011) The roles of dopamine and serotonin in decision making: evidence from pharmacological experiments in humans. Neuropsychopharmacology : official publication of the American College of Neuropsychopharmacology, 36(1), 114-32. PMID: 20881944
This is a look at the first study on the warrior gene’s effect on babies, and I reviewed the scientific literature on monoamine oxidase A (MAOA) in women and Asians, including epigenetics and gene expression, and hormone-gene interactions in aggression.... Read more »
Zhang M, Chen X, Way N, Yoshikawa H, Deng H, Ke X, Yu W, Chen P, He C, Chi X.... (2011) The association between infants' self-regulatory behavior and MAOA gene polymorphism. Developmental science, 14(5), 1059-1065. PMID: 21884321
Ever since the discovery and marketing of penicillin in 1928 by Alexander Fleming, bacteria have been developing resistance to antibiotics at an alarming rate. In many cases, resistant bacteria can be found lurking even before the new drug hits the market, making it only a matter of time before it becomes widespread.
Bacteria that are resistant to multiple antibiotics are commonly known as ‘superbugs’ and on one particularly virulent such bug is vancomycin-resistant Enterococcus faecium or VRE. VRE is an intestinal bacteria that lives in the human gut and is resistant to many antibiotics including vancomycin, which is currently one of the more powerful antibiotics used to treat other superbugs such as MRSA.... Read more »
Arias CA, Panesso D, McGrath DM, Qin X, Mojica MF, Miller C, Diaz L, Tran TT, Rincon S, Barbu EM.... (2011) Genetic basis for in vivo daptomycin resistance in enterococci. The New England journal of medicine, 365(10), 892-900. PMID: 21899450
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