Since my last blog post, where I shared my thoughts on BRCA1, BRCA2, and preventive mastectomies, I've been asked what else can a woman do to reduce her risk of breast cancer. I've heard a big deal about vitamin D, so I did a bit of research on the matter. As a disclaimer, I should tell you up front that, though many correlations between vitamin D deficiency and cancer risk have been found, just as many have been refuted or found inconclusive. You can read more about it on the wikipedia page.What is vitamin D? The name "vitamin D" includes a group of steroid-like molecules (they are similar to steroids, but not quite steroids) that help our intestine absorb calcium and phosphates. Since calcium is essential in bone development, vitamin D deficiency has been most commonly associated to osteoporosis and other bone-related diseases. There aren't many foods rich in vitamin D, however, vitamin D can be endogenously synthesized when the skin is exposed to sunlight. Unfortunately, modern lifestyle keeps us cooped up many hours in office cubicles, or in the house during chores, or in malls. When we're out enjoying the sunshine we cover up with hats and super-protective sunscreens because we've been told that the sun is bad for the skin and can cause malignancies. As a consequence, vitamin D deficiency is increasing world-wide. There is a foundation for all the studies that have analyzed correlations between several diseases, including cancers, and vitamin D: (i) several ecological studies have found a trend for an increase in incidence of certain cancers at higher latitudes, suggesting that longer exposures to the sun may have a protective effect. (ii) The vitamin D receptor (VDR) is expressed in many cells of the immune system, and mouse models have shown that vitamin D deficiency can promote certain auto-immune diseases. In a recent review, Sundaram and Coleman examine the link between vitamin D and influenza [Adv. Nutr. 2012 3: 517-525]. (iii) "VDR regulates a wide range of cellular mechanisms central to cancer development, such as apoptosis (cell death), cell proliferation (uncontrolled cell growth), differentiation, angiogenesis, and metastasis ". In line with this observation, Pereira, Larriba, and Munoz published a review on the evidence that vitamin D plays a protective role in colon cancer [Endocr. Relat. Cancer 2012 19: R51-R71].In , Crew discusses the use of vitamin D supplementation as part of breast cancer prevention. She presents many interesting findings, for example:"Colon, breast, and lung cancer have all demonstrated downregulation of expression of VDR when compared to normal cells and well-differentiated tumors have shown comparably more VDR expression as measured by immunohistochemistry when compared to their poorly differentiated counterparts. Higher tumor VDR expression has also been correlated with better prognosis in cancer patients ."Crew looks at different types of studies: some suggest beneficial effects from using vitamin D (calcitriol) in combination with other anti-cancer treatments; some found an inverse association with mammography density, a biomarker for breast cancer (supposedly high density increases the risk of cancer); some found an inverse association between better breast cancer prognosis and vitamin D deficiency. However, many of these studies have limitations. For example, some only assess the levels of vitamin D through dietary intake, which is not a good measure of the circulating levels because it doesn't account for vitamin D synthesized through sun exposure. Some were confounded by obesity since fat is known to sequestrate vitamin D and also raise breast cancer risk. In light of all these considerations, Crew concludes:"Even with substantial literature on vitamin D and breast cancer, future studies need to focus on gaining a better understanding of the biologic effects of vitamin D in breast tissue. Despite compelling data from experimental and observational studies, there is still insufficient data from clinical trials to make recommendations for vitamin D supplementation for breast cancer prevention or treatment ."As I often do in my posts, rather than giving you answers, I make an effort to provide you with pointers and food for thought: in the end you have to make your own decisions about your health and the wellbeing of your family. As a personal note, I'll add that on my last blood report my vitamin D circulating levels were undetectable. I had no symptoms whatsoever, but I am now taking a vitamin D supplement. I'm also much less paranoid about smothering my kiddos with sunscreen when they play outside (which has made them much happier, two birds with one stone).  Crew, K. (2013). Vitamin D: Are We Ready to Supplement for Breast Cancer Prevention and Treatment? ISRN Oncology, 2013, 1-22 DOI: 10.1155/2013/483687... Read more »
Crew, K. (2013) Vitamin D: Are We Ready to Supplement for Breast Cancer Prevention and Treatment?. ISRN Oncology, 1-22. DOI: 10.1155/2013/483687
Depression or Major Depressive Disorder (MDD) has multiple genetic and environmental causes. Genetic factors are hard to find and the discovered factors usually are also associated with other mood disorders. Furthermore, twin studies reveal that genetics can predict 37% of the depressions, which is a much lower heritability than in bipolar disorder, a comparable mood disorder (reviewed in Belmaker et al., 2008). ... Read more »
Papakostas, G., Shelton, R., Kinrys, G., Henry, M., Bakow, B., Lipkin, S., Pi, B., Thurmond, L., & Bilello, J. (2011) Assessment of a multi-assay, serum-based biological diagnostic test for major depressive disorder: a Pilot and Replication Study. Molecular Psychiatry, 18(3), 332-339. DOI: 10.1038/mp.2011.166
Pariante, C., & Lightman, S. (2008) The HPA axis in major depression: classical theories and new developments. Trends in Neurosciences, 31(9), 464-468. DOI: 10.1016/j.tins.2008.06.006
Raison, C. (2012) A Randomized Controlled Trial of the Tumor Necrosis Factor Antagonist Infliximab for Treatment-Resistant DepressionThe Role of Baseline Inflammatory BiomarkersInfliximab for Treatment-Resistant Depression. Archives of General Psychiatry, 1. DOI: 10.1001/2013.jamapsychiatry.4
Nibuya M, Morinobu S, & Duman RS. (1995) Regulation of BDNF and trkB mRNA in rat brain by chronic electroconvulsive seizure and antidepressant drug treatments. The Journal of neuroscience : the official journal of the Society for Neuroscience, 15(11), 7539-47. PMID: 7472505
Two hungry young galaxies that collided 11 billion years ago are rapidly forming a massive galaxy about 10 times the size of the Milky Way, according to UC Irvine-led research published Wednesday in the journal Nature.... Read more »
UC Irvine Media Realease. (2013) Fragile mega-galaxy is missing link in history of cosmos. UC Irvine. info:/
classical music and intense sensory exercises produced improvements in autism symptoms in children after just six months, scientists have found.... Read more »
Woo, C., & Leon, M. (2013) Environmental Enrichment as an Effective Treatment for Autism: A Randomized Controlled Trial. Behavioral Neuroscience. DOI: 10.1037/a0033010
Imagine you are the driver & your chocolate cravings are unruly passengers
If someone gave you a bag of 14 chocolates to carry around for five days, would you be able to resist eating them and any other chocolate? That was challenge faced by 135 undergrads in a new study that compared the effectiveness of two different "mindfulness" resistance techniques.
To help them, Kim Jenkins and Katy Tapper taught 45 of their participants "cognitive diffusion", the essence being that "you are not your thoughts". The students were told to imagine that they are the driver of a mindbus and any difficult thoughts about chocolate are to be seen as awkward passengers. The students chose a specific method for dealing with these difficult thoughts/passengers and practised it for five minutes - either describing them, letting them know who is in charge, making them talk with a different accent, or singing what they are saying.
Another group of students were taught an acceptance technique known as "urge surfing". They were instructed to ride the wave of their chocolate cravings, rather than to sink them or give in to them. A final group of students acted as controls and were taught a relaxation technique.
As well as trying to resist the bag of chocolates, the students in all conditions were asked to avoid eating any other chocolate as far as possible, and to keep a diary of any chocolate they did eat over the five days.
The key finding is that the mindbus group ate fewer chocolates from their bag as compared with students in the control group. By contrast, the urge surfing group ate just as many of their chocolates as the controls. Diary records showed the differences between groups in their other chocolate consumption was not statistically significant, although there was a trend for the mindbus group to eat less (13g vs. 52g in the urge surfing group and 44g in the control condition). Another way of describing the results is to say that 27 per cent of the mindbus group ate some chocolate over the five-day period, compared with 45 per cent of the urge surfers and 45 per cent of controls.
A habits questionnaire suggested the mindbus technique was more effective because it reduced the students' mindless, automatic consumption of chocolate more than the other interventions. Jenkins and Tapper said their results show the mindbus "cognitive diffusion" technique is a "promising brief intervention strategy" for boosting self-control over an extended time period.
The serious chocaholics among you may not be so convinced. Although the students were recruited on the basis that they wanted to reduce their chocolate consumption, they appeared to show saintly levels of abstinence. On average, even the control group participants ate just 0.69 chocolates from their bag over the five day period (compared with an average of 0.02 chocolates in the mindbus condition; 0.27 in the urge surfing condition). The controls other chocolate consumption amounted to the equivalent of little more than four individual chocolates over five days. You've got to wonder - how serious were these participants about chocolate and just how tasty were the chocolates in that bag?
Another thing - the researchers included a measure of "behavioural rebound". After the students returned to the lab on day five, they were presented with a bowl of chocolates and invited to eat as many as they liked. The groups didn't differ in the amount of chocolates they consumed, which the researchers interpreted as a good sign - after all, the mindbus group hadn't compensated for their restricted intake during the week. But hang on, they also showed no evidence of greater resistance to the chocolate. Sounds to me like the passengers had taken over the bus.
Jenkins, K., and Tapper, K. (2013). Resisting chocolate temptation using a brief mindfulness strategy. British Journal of Health Psychology DOI: 10.1111/bjhp.12050
Post written by Christian Jarrett (@psych_writer) for the BPS Research Digest.
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Jenkins, K., & Tapper, K. (2013) Resisting chocolate temptation using a brief mindfulness strategy. British Journal of Health Psychology. DOI: 10.1111/bjhp.12050
An episode of the BBC program Horizon on 'Big Data' recently caught my attention. The content was a fascinating insight into how we are living in a data-rich age and how trawling/mining/dredging such data has the ability to advance medicine, predict crime and even make someone a few quid/dollars/euros on the stock market.Gone (data) fishing @ Wikipedia I'm a big believer in big data. In particular how, with the right sources, technology, techniques and people, big data might be able to open up some real insights into many important areas including mental health research* and very possibly autism research with a specific focus on the science of biomarkers to aid things like early diagnosis. Indeed, I'm not the only one talking about this (see here).I've spoken before on this blog about biomarkers for autism and other conditions - the promises, the problems, the future - and how alongside the various autism research banks (genes, brains, etc.) and systems biology chatter, we are just starting to understand the value of those big data resources such as the archived bloodspot samples which so many neonates provide these days.Indeed with the greatest appreciation for pioneers like Robert Guthrie, I offer a post on an interesting paper by Gerald Mizejewski and colleagues** discussing results suggestive of potential candidate biomarkers for autism based on archived bloodspot samples. I should point out that this is not the first time that Dr Mizejewski has talked about the feasability of biomarkers for autism as per this article*** (open-access) as part of quite a distinguished research career it has to be said (see here) with a specific focus on an interesting molecule called alpha-fetoprotein****.The most recent paper is unfortunately not at the time of writing open-access, so I'll just go through a few summary points about the work:This was a retrospective study based on that tantalising resource of archived bloodspot cards which sit in many a hospital basement. Out of a total case group of 200 families with a child with autism, 40 families with children aged between 3-5 years old were initially contacted for participation. This was eventually whittled down to 16 participants (all diagnosed with autism by the same clinician with the same diagnostic manual) for whom archived neonatal bloodspot cards were available. Two age-matched control specimens located immediately before and after the dried bloodspot card in question in the filing system were also chosen.A small 3mm punch of the Guthrie cards was analysed by immunoassay which in this case, probed for 90 potential biomarkers covering everything from neurotrophins to cytokines, immunoglobulins to more direct inflammatory markers (including C-reactive protein).Some fancy statistical modelling was applied to the obtained results - including Bayesian information criterion (BIC) - which eventually resulted in three models of best-fit based on findings from the bloodspots of those who went to be diagnosed with an autism spectrum disorder (ASD). The 'best model' of five compounds included some familiar names to this blog: glutathione-S-transferase (GST), IL-7, IL-5, TNF-beta and something called Lp(a) (lipoprotein a). Most were increased in quantity in the autism samples aside from GST which was decreased.There is a very nice illustration in the paper (Figure 3) showing how the potential connections between the biomarkers identified and some of the more biomedical themes of autism research might fit. So we have methionine metabolism mentioned (see here and here), oxidative stress (see here), gastrointestinal comorbidity (see here) and immune activation (see here) to name a few. It's all very systems biology.The authors caution that their results are preliminary and that although said biomarkers were modelled as being related to autism they "have not been confirmed to be causative with autism".Before I get too carried away with this research, there are a few issues worth mentioning. Yes, the sample size was small in this preliminary communication and indeed very little information is provided about participants outside of just them fulfilling the DSM-IV criteria for autism in terms of things like comorbidity. Also why out of 200 families such a small number of participants were eventually included for study.Indeed there is also an assumption from this study that a biomarker for autism is present in the neonatal phase which for example, might not take into account the issue of behavioural regression that seems to cover quite a percentage of cases.Whilst the identified best-fit biomarkers are of potentially real interest to autism research as per other similar studies (see here), it is the method and resources used in this paper which is the real 'big data' story allied to all those lovely -omics which reign supreme these days. Parents in many countries will be acquainted with that bloodspot taken during the earliest days of infancy to test for various inborn errors of metabolism such as phenylketonuria (PKU). Many people don't however give a second thought to what happens to those bloodspot cards, and how valuable a resource they might constitute. Although not usually in the business of crystal-ball gazing, I would hazard a guess that we are one day going to hear big news about the big data from those archived bloodspot cards; if not with autism in mind, then something else. ----------* Ayers JW. et al. Seasonality in seeking mental health information on Google. Am JPrev Med. April 2013.** Mizejewski GJ. et al. Newborn screening for autism: in search of candidate biomarkers. Biomark Med. 2013; 7: 247-260.*** Mizejewski GJ. Biomarker testing for suspected autism spectrum disorder in early childhood: is such testing now feasible? Biomark Med. 2012; 6: 503-506.**** Mizejewski GJ. Biological roles of alpha-fetoprotein during pregnancy and perinatal development. Exp Biol... Read more »
Mizejewski GJ, Lindau-Shepard B, & Pass KA. (2013) Newborn screening for autism: in search of candidate biomarkers. Biomarkers in medicine, 7(2), 247-60. PMID: 23547820
The IRS kerfuffle has increased interest in the tax code by about 5700%, and one outcome is that people are starting to put the various exemption groups under a microscope. Dylan Matthews has thoughtful piece on 501(c)4 organizations, the groups at the center of the scandal. Matthews thinks the real issue is disclosure, and it’s [...]... Read more »
Dowling, C., & Wichowsky, A. (2013) Does It Matter Who's Behind the Curtain? Anonymity in Political Advertising and the Effects of Campaign Finance Disclosure. American Politics Research. DOI: 10.1177/1532673X13480828
The carbon footprint from running shoes... Read more »
Cheah, L., Ciceri, N., Olivetti, E., Matsumura, S., Forterre, D., Roth, R., & Kirchain, R. (2013) Manufacturing-focused emissions reductions in footwear production. Journal of Cleaner Production, 18-29. DOI: 10.1016/j.jclepro.2012.11.037
Everybody’s an expert these days. Pest Control Expert, Plumbing Expert, Weather Expert, and so on. What does it really mean to have expertise? Take a minute to think about what expertise means to you. If ideas like superior intelligence, heightened perceptual skills, and photographic memory come to mind, you may be thinking of superheroes, or [...]... Read more »
Ericsson, K., & Ward, P. (2007) Capturing the Naturally Occurring Superior Performance of Experts in the Laboratory: Toward a Science of Expert and Exceptional Performance. Current Directions in Psychological Science, 16(6), 346-350. DOI: 10.1111/j.1467-8721.2007.00533.x
Hatano, G., & Inagaki, K. (1984) Two courses of expertise. Research and Clinical Center for Child Development Annual Report, 27-36. info:/
Offshore drilling is often discussed in terms of its positive effect on the economy and the potential risks it carries for the environment. There’s, however, another side to offshore drilling, one that is less often talked about.... Read more »
Parnell, J., Boyce, A., Hurst, A., Davidheiser-Kroll, B., & Ponicka, J. (2013) Long term geological record of a global deep subsurface microbial habitat in sand injection complexes. Scientific Reports. DOI: 10.1038/srep01828
Teasing out the insulin effect.
On the face of it, the study seems to come out of left field: A group of researchers claimed that marijuana smokers showed 16 per cent lower fasting insulin levels than non-smokers. The study, called “The Impact of Marijuana Use on Glucose, Insulin, and Insulin Resistance among US Adults,” is in press for The American Journal of Medicine. The authors are a diverse group of medical researchers from Harvard, Beth Israel Deaconess Medical Center, and the University of Nebraska College of Medicine. The study concluded: “We found that marijuana use was associated with lower levels of fasting insulin and HOMA-IR [a measure of insulin resistance], and smaller waist circumference.”
Of course, it was that last tidbit about waist circumference that was picked up by the media. “Why Pot Smokers Are Skinnier,” headlined the Atlantic. However, the important implications are not so much for weight control, or the discovery of some built-in offsetting mechanism for the marijuana munchies, but rather for insulin control and the treatment of diabetes.
But in a clinical study, remarkable observations require remarkable documentation. What does the research actually say?
There are problems with the study worth noting. While researchers took blood samples after a 9-hour fast to determine insulin and glucose levels, they relied on self-reporting for marijuana use data. And self-reporting for alcohol and drug use has its limitations as an investigative tool. Namely, lack of honesty. But let’s get beyond that for a moment: From a database of 4, 657 men and women who participated in the National Health and Nutrition Examination Survey, the researchers determined that 579 were current marijuana users, while 1, 975 were pot smokers in the past.
The marijuana-smoking cohort tended to be young males who also smoked cigarettes. After running everything through a series of complicated multivariable-adjusted models, marijuana came out associated with lower insulin levels, and “lower waist circumference” than those who reported never using marijuana. And the results didn’t change much after adjusting for BMI numbers and excluding participants who actually had diabetes. Furthermore, the association was strongest in current smokers, “suggesting that the impact of marijuana use on insulin and insulin resistance exists during periods of recent use.” (It should also be noted that other health habits can effect glucose and insulin activity, including cigarettes, alcohol, and lack of physical activity.)
The investigators don’t offer a solution to the increased appetite/decreased waistline conundrum they claim to have identified. “We did not find any significant associations between marijuana use, and triglyceride levels, systolic blood pressure, or diastolic blood pressure,” they concluded.
We know marijuana has a complicated relationship with appetite mechanisms, as evidence by its use with chemotherapy patients who need to eat. The theory is that the metabolic effects are mediated by a complex mix of cannabinoid type 1 and type 2 receptor interactions, since type 1 receptor antagonists like rimonabant improve insulin resistance in humans, and type 1 knockout mice also show resistance to diet-induced obesity.
Does marijuana smoking protect against diabetes? Wisely, the researchers don’t go that far, on the basis of this one uncontrolled study. The researchers’ conclusions neatly hedge the bets, suggesting that with recent trends in the direction of marijuana legalization, “physicians will increasingly encounter patients who use marijuana and should therefore be aware of the effects it can have on common disease processes, such as diabetes mellitus.”
As it happens, the findings aren’t entirely new. Anecdotal reports abound. Back in 2010, on the Diabetes Daily support board, there was a long discussion of marijuana’s effect on blood glucose levels in diabetics. And there are several mouse models showing the same effects. In a prepared statement, lead investigator Murray A. Mittleman of Beth Israel Deaconess Medical Center in Boston conceded that previous epidemiological studies have found “lower prevalence rates of obesity and diabetes mellitus in marijuana users compared to people who have never used marijuana, suggesting a relationship between cannabinoids and peripheral metabolic processes.” However, he believes that “ours is the first study to investigate the relationship between marijuana use and fasting insulin, glucose, and insulin resistance.”
Perhaps so. A 2011 study in the American Journal of Epidemiology concluded that “the prevalence of obesity is lower in cannabis users than in nonusers.” And the British Medical Journal featured a finding in 2012 by Los Angeles researchers that marijuana use was “independently associated with a lower prevalence of diabetes mellitus.” But the online patient guide for marijuana offered by Mayo Clinic says without equivocation that “cannabis may lower blood sugar. Caution is advised in patients with diabetes or hypoglycemia, and in those taking drugs, herbs, or supplements that affect blood sugar.” In fact, Mayo Clinic advises that patients may want to monitor their blood glucose levels if they smoke medical marijuana.
Regarding the current study, the editor-in-chief of the American Journal of Medicine said in a statement that there is a need for “a great deal more basic and clinical research into the short- and long-term effects of marijuana in a variety of clinical settings such as cancer, diabetes, and frailty of the elderly.” Editor Joseph S. Alpert also called on the National Institutes of Health (NIH) and the Drug Enforcement Administration (DEA) to collaborate in “developing policies to implement solid scientific investigations that would lead to information assisting physicians in the proper use and prescription of THC in its synthetic or herbal form.”
Penner E.A., Buettner H. & Mittleman M.A. (2013). The Impact of Marijuana Use on Glucose, Insulin, and Insulin Resistance among US Adults, The American Journal of Medicine, DOI: 10.1016/j.amjmed.2013.03.002
Photo Credit: http://www.herbalmission.org/
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Penner Elizabeth A., Buettner Hannah, & Mittleman Murray A. (2013) The Impact of Marijuana Use on Glucose, Insulin, and Insulin Resistance among US Adults. The American Journal of Medicine. DOI: 10.1016/j.amjmed.2013.03.002
A few of us have started a Decision Theory journal club where we plan on reading papers from a variety of fields that examine how decisions are made. We have people from neuroscience, economics, and cognitive science participating (so far), including people participating through Google+ hangouts!, which will hopefully make lead to some productive discussions. […]... Read more »
Brunton, B., Botvinick, M., & Brody, C. (2013) Rats and Humans Can Optimally Accumulate Evidence for Decision-Making. Science, 340(6128), 95-98. DOI: 10.1126/science.1233912
Znamenskiy, P., & Zador, A. (2013) Corticostriatal neurons in auditory cortex drive decisions during auditory discrimination. Nature, 497(7450), 482-485. DOI: 10.1038/nature12077
Scientists have found that the complex biochemical changes through RNA may have been occurred in the start of the life on early Earth.
RNA (full form: ribonucleic acid) is a nucleic acid that has the sugar ribose, is found in all living cells, and is essential for the manufacture of proteins according to the instructions carried by genes. RNA also acts instead of DNA as the genetic material in certain viruses.
RNA is thought to play an important role in the start of life on Earth more than 3 billion years ago, when environment had less oxygen and a huge amount of soluble iron, and the complex biochemical transformations were thought to be rare.
Researchers worked on the 23S ribosomal RNA and transfer RNA, two most important and plentiful types of RNA, and found their ability to catalyze electron transfer in the presence of iron and lack of oxygen.
“Our study shows that when RNA teams up with iron in an oxygen-free environment, RNA displays the powerful ability to catalyze single electron transfer, a process involved in the most sophisticated biochemistry, yet previously uncharacterized for RNA,” said Loren Williams, a professor in the School of Chemistry and Biochemistry at the Georgia Institute of Technology.
Based on these findings researchers noted that RNA may have some yet-to-be-discovered abilities in the living beings on ancient Earth.
“Our findings suggest that the catalytic competence of RNA may have been greater in early Earth conditions than in present conditions, and our experiments may have revived a latent function of RNA,” added Williams, who is also director of the Ribo Evo Center.
Hsiao, C., Chou, I., Okafor, C., Bowman, J., O'Neill, E., Athavale, S., Petrov, A., Hud, N., Wartell, R., Harvey, S., & Williams, L. (2013). RNA with iron(II) as a cofactor catalyses electron transfer Nature Chemistry, 5 (6), 525-528 DOI: 10.1038/nchem.1649... Read more »
Hsiao, C., Chou, I., Okafor, C., Bowman, J., O'Neill, E., Athavale, S., Petrov, A., Hud, N., Wartell, R., Harvey, S.... (2013) RNA with iron(II) as a cofactor catalyses electron transfer. Nature Chemistry, 5(6), 525-528. DOI: 10.1038/nchem.1649
Recently we attended the Medical Library Association conference (#MLAnet13). Librarians are working so hard to wrangle information into usable forms, and to generate new connections among data types to reveal new information and leads for further studies. I ♥ librarians. In one of the sessions I attended on Medical Informatics, I heard several great talks. One [...]... Read more »
Rabinowitz, P., Scotch, M., & Conti, L. (2010) Animals as Sentinels: Using Comparative Medicine To Move Beyond the Laboratory. ILAR Journal, 51(3), 262-267. DOI: 10.1093/ilar.51.3.262
Rabinowitz, P., Gordon, Z., Holmes, R., Taylor, B., Wilcox, M., Chudnov, D., Nadkarni, P., & Dein, F. (2005) Animals as Sentinels of Human Environmental Health Hazards: An Evidence-Based Analysis. EcoHealth, 2(1), 26-37. DOI: 10.1007/s10393-004-0151-1
Rabinowitz, P., Cullen, M., & Lake, H. (1999) Wildlife as sentinels for human health hazards: a review of study designs. Journal of Environmental Medicine, 1(4), 217-223. DOI: 10.1002/jem.33
CrossFit Regionals Competitions s are almost here. Athletes should arrive well rested and hopefully injury free. CrossFit Regionals competitions are very intense. Athletes will have to complete several WODs aThe post CrossFit Regionals Competitions: Ice Baths and Deep Massage. Do they help? appeared first on WODMasters Stiff Competition.... Read more »
Delextrat A, Calleja-González J, Hippocrate A, & Clarke ND. (2013) Effects of sports massage and intermittent cold-water immersion on recovery from matches by basketball players. Journal of sports sciences, 31(1), 11-9. PMID: 22935028
Canine cognition is a hot topic these days, using experiments and brain imaging as research tools. The trouble with brain imaging work is that it is invasive, to the extent that animals may have to be sedated or anaesthetized for the study. All that changed with the amazing work of Gregory Berns et al and the first-ever fMRI study on awake, unrestrained dogs last year. Now Miiamaaria Kujala et al in Finland have shown that it is also possible to do a non-invasive EEG with dogs.An EEG measures brain activity by placing electrodes across the scalp. These pick up oscillations in electrical activity, which can be measured for changes. One common use of EEG is in assessing epilepsy in dogs (and people). We aren’t talking about veterinary EEGs here, however, but those designed to learn something about how a healthy brain works.If animals have to be anaesthetized for an EEG to occur, it’s a problem because a drowsy brain does not function in the same way as an alert brain. Awake animals are typically restrained. For example, Hanlu Ma et al (2013) anaesthetized cats and surgically implanted metal tubes through which electrodes could be inserted. After the cats were given a couple of weeks to recover from surgery, the electrodes were used to test the cats’ responses to meows and to human voices making vowel sounds. The cat’s body was wrapped in a cotton bag and its head was immobilized while the sounds were played. The cats were trained for this (though the paper doesn't say how) and monitored for signs of distress. The results showed which parts of the brain were activated, and found no significant difference in response to meows and vowels. In this study, the cats were awake. But it is still invasive, since they had to be operated on and were restrained for several hours at a time. Could there be another way?Since dogs are easily trainable using operant conditioning, Kujala et al in Finland thought it might be possible to train dogs for EEG. Using positive reinforcement, they trained eight beagles to take part in their study. The beagles were purpose-bred for laboratory work and live in a group kennel environment. First of all they took part in training. For the study, their heads had to be shaved, cleaned and prepped so that electrodes could be applied. They wore seven electrodes on the head, one in each ear, and a ground electrode on the back. Then they had to lie still and look at a TV screen while measurements were taken. At the same time, they also wore eye-tracking equipment. A beagle in the study. Source: PLoS OneThe experiment itself took place in twenty-minute sessions over four days for each dog, so that they did not get too tired. Of course, it took much longer to train the dogs to get used to the laboratory and the equipment in the first place, with twice-weekly training sessions over one and a half years.The dogs were shown photographs of human and dog faces, mostly the right way up but with some upside-down. They were shown a batch of photos, then had a short break in which they were rewarded with some food, then led to settle down and watch another batch. The authors point out that the experimental set-up is very similar to that used in human studies. The results showed a change in a type of electrical activity called the beta range (15-30Hz); oscillations in this band were suppressed when the dog was looking at a face, compared to the rest period. This probably reflects the activity of a part of the brain called the occipital cortex. In addition, the researchers found a suppression of activity at the 2-6Hz range. This coincided with the beginning of looking at an image, and was noticed most in the sensors at the front of the head. The authors say this may relate to eye movements as the dog looks at an image that has just appeared on the TV.There were individual differences between the dogs which is not surprising, as this is also the case for humans. The authors conclude that “the study opens the possibility to implement cognitive neuroscience studies with dogs and to examine the evolutionary background and divergence of brain function associated with cognition.”This is similar to the study by Gregory Berns et al that was published last year. They trained two dogs – Callie the rescue feist and McKenzie the agility-loving border collie – to take part in an fMRI. They began training the dogs using a mock-up of the equipment before moving on to the real version. After two months, they were able to take part in the fMRI study. Each dog had to keep absolutely still; if they moved by as little as 3mm, it would make the data useless. Source: PLoS OneThe picture shows Callie during a training session (A) and McKenzie during the study itself (B). The study found that the reward centre of the brain lit up when the dog saw a hand signal that meant a treat would soon be forthcoming. These EEG and fMRI studies are a tremendous achievement on the part of both the humans and dogs that took part. So how were the dogs trained? They did not use electric shocks or ‘corrections’ or punishment. Instead they relied on positive reinforcement. (You will have noticed ongoing positive reinforcement in the EEG study, with pauses in which the dog was given a treat before returning to the experiment).These two studies were designed to find out about the canine brain, but they also show the effectiveness of training using positive reinforcement.Some people (even some dog trainers) try to argue that positive reinforcement is not the right way to train a dog. And yet, it has been used to train dogs to take part in an EEG study and in fMRI without the need for sedation or restraint. Isn’t that amazing?! ReferencesBerns, G., Brooks, A., & Spivak, M. (2012). Functional MRI in Awake Unrestrained Dogs ... Read more »
Kujala, M., Törnqvist, H., Somppi, S., Hänninen, L., Krause, C., Vainio, O., & Kujala, J. (2013) Reactivity of Dogs' Brain Oscillations to Visual Stimuli Measured with Non-Invasive Electroencephalography. PLoS ONE, 8(5). DOI: 10.1371/journal.pone.0061818
Ma, H., Qin, L., Dong, C., Zhong, R., & Sato, Y. (2013) Comparison of Neural Responses to Cat Meows and Human Vowels in the Anterior and Posterior Auditory Field of Awake Cats. PLoS ONE, 8(1). DOI: 10.1371/journal.pone.0052942
A great deal of Twitter content has been described as "pointless babble." However, an experimental study found that Twitter usage can ward off existential anxiety, at least in extraverts. Even banal tweets might serve a deeper psychological purpose.... Read more »
Qiu L, Leung AK, Ho JH, Yeung QM, Francis KJ, & Chua PF. (2010) Understanding the psychological motives behind microblogging. Studies in health technology and informatics, 140-4. PMID: 20543286
It’s no secret that carnivorous plants are just way cool. Yet despite all the attention, there is still a lot we don’t know about them. Recent studies have expanded the view we have of these plants so that we now recognize more and more of them – like tomatoes and potatoes. Yes, our vegetables are insectivores!
New research has show that pitcher plants possess anti-microbial peptides in their pitchers, that some sundews can catapult insects into their traps in just a few milliseconds, and that underwater carnivorous plants use a vacuum-packed trap door to suck prey into a trap. Or how about that pitcher plant that hopes a tree shrew will use it for a toilet?!
... Read more »
Poppinga, S., Hartmeyer, S., Seidel, R., Masselter, T., Hartmeyer, I., & Speck, T. (2012) Catapulting Tentacles in a Sticky Carnivorous Plant. PLoS ONE, 7(9). DOI: 10.1371/journal.pone.0045735
Buch, F., Rott, M., Rottloff, S., Paetz, C., Hilke, I., Raessler, M., & Mithofer, A. (2012) Secreted pitfall-trap fluid of carnivorous Nepenthes plants is unsuitable for microbial growth. Annals of Botany, 111(3), 375-383. DOI: 10.1093/aob/mcs287
Schulze, W., Sanggaard, K., Kreuzer, I., Knudsen, A., Bemm, F., Thogersen, I., Brautigam, A., Thomsen, L., Schliesky, S., Dyrlund, T.... (2012) The Protein Composition of the Digestive Fluid from the Venus Flytrap Sheds Light on Prey Digestion Mechanisms. Molecular , 11(11), 1306-1319. DOI: 10.1074/mcp.M112.021006
When animals live caves full time, their descendents often lose their eyes. It has happened over and over and over and over again, in all different kinds of animals. But how this happens is not obvious. Stephen Jay Gould wrote that some people would use cave fish as an argument that “Lamarck must have been on to something” with his idea that acquired characteristics can be inherited. Well, no, that’s not that case, but it is a good example of how tricky thinking about losses can be.
The latest paper to try to sort out eye loss uses small amphipod crustaceans (Gammarus minus). An advantage of working with this particular species is that some populations live out in the sunshine with us, but several populations have gone down in the underground. In this case, Carlini and colleagues have three separate populations that went into caves, and they have their closest relatives, which are not cave dwellers. Each pair of populations acts as a natural experiment.
The eyes do change with the habita, as expected. The amphipods that live “above” in springs have eyes with about 40 facets (ommatidia), while the cave dwellers’eyes have about 5 ommatidia.
Using genetic tests, the team found that the genes for making visual pigments, the opsins, were still intact. They had not turned into non-working genes (“pseudogenes”). The genes for the opsins were extremely similar, and in no way as different as the eyes of these little guys were.
What they did find was that the expression of these genes was dialed way down compared to their surface dwelling relatives:
Carlini and colleagues note that this could be related to the overall reduction of the eye, but they attempted to control for this by scaling expression to the size of the eyes.
Carlini and colleagues suggest that the opsin genes are under some sort of pressure to stay “intact” in this species (contrary to suggestion here that there is an advantage to blindness in caves). But the team doesn’t have a suggestion for what the opsin genes might be needed for, although they suggest it might be a non-visual function.
This doesn’t solve the matter of how the animals are reducing the amount of opsins they make. Presumably there is some mutation in a regulatory gene, perhaps even a gene one specific to the visual system.
They should keep an eye out for that.
Carlini DB, Satish S, Fong DW. 2013. Parallel reduction in expression, but no loss of functional constraint, in two opsin paralogs within cave populations of Gammarus minus (Crustacea: Amphipoda). BMC Evolutionary Biology 13(1): 89. DOI: 10.1186/1471-2148-13-89
“What big eyes you have!”
Turning light and going blind: A tale of caves and genes
Once more into the cave
Better off blind
Picture from here.... Read more »
Carlini David B, Satish Suma, & Fong Daniel W. (2013) Parallel reduction in expression, but no loss of functional constraint, in two opsin paralogs within cave populations of Gammarus minus (Crustacea: Amphipoda). BMC Evolutionary Biology, 13(1), 89. DOI: 10.1186/1471-2148-13-89
Individuals who learn two languages at an early age seem to switch back and forth between separate “sound systems” for each language, according to new research conducted at the University of Arizona.... Read more »
Anna Mikulak. (2013) Study Shows How Bilinguals Switch Between Languages. Association for Psychological Science. info:/
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