Some call it the data deluge, others the Fourth Paradigm – whatever your phrase of choice, it’s undeniable that science is increasingly driven by the easy availability of large amounts of data. The web is instrumental in their dissemination around the world. Web service providers such as Amazon enable storage of and access to data in the cloud. Continuing our progress in the exploration of the natural world depends ever more crucially on our ability to curate data and extract information from it.... Read more »
Dustin Lang, & David W. Hogg. (2011) Searching for comets on the World Wide Web: The orbit of 17P/Holmes from the behavior of photographers. Arxiv. arXiv: 1103.6038v1
(*In honor of the upcoming NBA playoffs, a brief post on, for my money, the big paradox of professional sports: the myth of the hot hand.) Despite a long and fruitful career full of notable findings, Cornell psychologist Thomas Gilovich is perhaps most well known for a study he conducted with psychologists Amos Tversky and [...]... Read more »
GILOVICH, T. (1985) The hot hand in basketball: On the misperception of random sequences*1. Cognitive Psychology, 17(3), 295-314. DOI: 10.1016/0010-0285(85)90010-6
ADAMS, R. (1992) THE "HOT HAND" REVISITED: SUCCESSFUL BASKETBALL SHOOTING AS A FUNCTION OF INTERSHOT INTERVAL. Perceptual and Motor Skills, 74(3), 934. DOI: 10.2466/PMS.74.3.934-934
Several beautiful and intriguing images are presented below, graciously made creative commons material by the Nanoscale Informal Science Education Network, a foundation that seeks to improve public engagement in nanoscale science in engineering. Try your hand at guessing what is depicted in each of these images, and when you get stumped, scroll on down to discover the science behind each image, as brought to you by the author of From The Lab Bench. Enjoy!... Read more »
Heller, E., Crommie, M., Lutz, C., & Eigler, D. (1994) Scattering and absorption of surface electron waves in quantum corrals. Nature, 369(6480), 464-466. DOI: 10.1038/369464a0
Feng, L., Zhang, Y., Xi, J., Zhu, Y., Wang, N., Xia, F., & Jiang, L. (2008) Petal Effect: A Superhydrophobic State with High Adhesive Force. Langmuir, 24(8), 4114-4119. DOI: 10.1021/la703821h
do_sud_thumb("http://neurobonkers.com/wp-content/uploads/2011/04/ObviousTroll1.jpg","Throwing babies at wind-shields and... Read more »
Gilliam CM, Diefenbach GJ, Whiting SE, & Tolin DF. (2010) Stepped care for obsessive-compulsive disorder: An open trial. Behaviour research and therapy, 48(11), 1144-9. PMID: 20728075
There have been huge fights in the past decade over Naval sub-hunting sonar and its effects on certain species of whales. In several cases, mass strandings of marine mammals have occurred shortly after naval exercises where mid-frequency active (MFA) sonar … Continue reading →... Read more »
Tyack PL, Zimmer WM, Moretti D, Southall BL, Claridge DE, Durban JW, Clark CW, D'Amico A, Dimarzio N, Jarvis S.... (2011) Beaked whales respond to simulated and actual navy sonar. PloS one, 6(3). PMID: 21423729
T.M. Cox, T.J. Ragen, A.J. REad, E. Vos, R.W. Baird, K. Balcomb, et al. (2006) Understanding the impacts of anthropogenic sound on beaked whales. Journal of Cetacean Research and Management, 7(3), 177-187. info:/
This past week, British newspapers carried sensational headlines about an archaeological find in Prague: “First Homosexual Caveman Found” (The Telegraph) and “Oldest Gay in the Village: 5,000 Year Old is ‘Outed’ By the Way He Was Buried” (Daily Mail). Although the assemblage in question has not been published in a journal, the archaeologists called a [...]... Read more »
Grosman, L., Munro, N., & Belfer-Cohen, A. (2008) A 12,000-year-old Shaman burial from the southern Levant (Israel). Proceedings of the National Academy of Sciences, 105(46), 17665-17669. DOI: 10.1073/pnas.0806030105
Discussion of primate phylogeny... Read more »
They're called books... Okay, that's a bit of media sensationalism there, but according to a recent study in the Archives of Pediatrics and Adolescent Medicine adolescents who reported reading more print media (books, magazines, newspapers, etc.) were less likely to be diagnosed with major depressive disorder (MDD), while adolescents who spent more time spent listening to music had an increased likelihood of a diagnosis of MDD. The study took advantage of a fairly new technique known as ecological momentary assessment, which basically allows researchers to take a bunch of individual "snapshots" of people's behavior as if they were animals in the wild. Rather than invite people to come into a university lab or office and fill out a survey where the subjects might over- or under-estimate how much time they spent on a given activity, study participants agree to be called randomly on their cell phones and answer a small, instantaneous survey. In this particular study, researchers called more than 100 adolescents over a period of about 2 months, calling each participant 60 times and asking whether they had, at that moment, been watching television, playing video games, surfing the internet, listening to music, or reading a book (or magazine, etc.). The results suggest that the more time adolescents spent listening to music, the more likely they were to be diagnosed with MDD. Conversely, the more time they spent reading books or other print media, the less likely they were to get such a diagnosis. Of course, this doesn't necessarily mean that books have any antidepressant properties (or that music will make you morose or melancholy), rather it is likely that adolescents who are depressed are more apt to spend their time listening to music and less likely to spend it reading books. Still, it will be interesting to see what comes from this line of research.And, in case you were wondering, time spent watching tv, surfing the web, or playing video games did not appear to strongly correlate either way with MDD diagnoses.Primack BA, Silk JS, Delozier CR, Shadel WG, Dillman Carpentier FR, Dahl RE, & Switzer GE (2011). Using ecological momentary assessment to determine media use by individuals with and without major depressive disorder. Archives of pediatrics & adolescent medicine, 165 (4), 360-5 PMID: 21464384... Read more »
Primack BA, Silk JS, Delozier CR, Shadel WG, Dillman Carpentier FR, Dahl RE, & Switzer GE. (2011) Using ecological momentary assessment to determine media use by individuals with and without major depressive disorder. Archives of pediatrics , 165(4), 360-5. PMID: 21464384
Are you getting excited about the Royal Wedding yet? (Even if you’re not, Brits have an extra day off work to look forward to!) In a world with frighteningly high divorce rates, and facing a life in the limelight, is there really any hope that the royal marriage can survive a lifetime? Well here are some [...]... Read more »
Wilcox, W., & Dew, J. (2010) Is love a flimsy foundation? Soulmate versus institutional models of marriage☆. Social Science Research, 39(5), 687-699. DOI: 10.1016/j.ssresearch.2010.05.006
Vision is so important to humans that it is difficult to imagine how we can produce a conscious model of the world without it. And what is done with the third of the cortex that is involved in vision when it is idle. Kupers and others (see citation) have been comparing fMRI scans using congenitally [...]... Read more »
Kupers, R., Pietrini, P., Ricciardi, E., & Ptito, M. (2011) The Nature of Consciousness in the Visually Deprived Brain. Frontiers in Psychology. DOI: 10.3389/fpsyg.2011.00019
My young daughter does not like ants. This is a bit troublesome at this time of the year when garden ants are everyhwere. Yesterday, she pointed at something on the ground. I looked at I saw what looked like an ant carrying another ant running very fast. It must have looked a bit odd as I stopped the "ant" putting my hand in front of it. She hid underneath and I slowly lifted my hand and took a couple of shots. Only when revising the shots did I realised that the ant was only an illusion: it was a spider, but one that strongly resembles an ant not only in size, general shape, shininess, but also in posture and behaviour. She carried her front legs raised so that it looks like its got antennae and six legs, and its movements were most reminiscent of the manic running of ants in hot weather.In her review of ant mimicry in spiders Paula Cushing stated referring to morphological spider modifications to resemble ants:They include a variety of color and body-form modifications that give the spider the appearance of having three body segments instead of two and of having long, narrow legs instead of shorter, more robust legs. Mandibles, compound eyes and even stings are sometimes mimicked by the spiders through modifications in the chelicerae, pigmentation in the cuticle, or special positioning of the spinnerets. In many cases, the extent to which the mimics resemble a particular model is extraordinaryThe following table helps in dispelling the notion that this ant resemblance is just a fantasy of the observer.There are many species of invertebrates that have evolved to resemble ants including crickets, bugs, beetles, springtails, and even flies. At least 100 species of spiders of 12 families mimic ants. The formal name for this phenomenon is ant mimicry or myrmecomorphy. But why would a spider evolve to look like an ant? A few spiders resembles ants in order to get close to them and eat them (aggressive mimicry), but the most ant mimic spiders benefit from visual predators taking them for ants, and avoid eating them. This is a case of protective or Batesian mimicry, the mimic imitating a dangerous model. Ants can be distasteful or aggressive or both, with biting mandibles, a spray of formic acid and a sting. Given that the deception is visual the selective agent must be highly visual: birds, wasps, hunter spiders that normally avoid ants would avoid an ant mimic in the same way, therefore a small spider may have much to gain from resembling a common local ant. My little ant-spider is most likely Micaria pulicaria, a widespread species in the U.K. often found running in the company of common garden ants. It is not reported that it preys on ants so, the reason for its ant mimicry, most likely involves Batesian mimicry. Interestingly, it is the only diurnal genus in a mostly nocturnal hunter spider family - Gnaphosidae, for an example see this post - and ant mimicry might have help this spider lineage conquer and diversify in a diurnal niche.ReferencesCushing, P. (1997). Myrmecomorphy and Myrmecophily in Spiders: A Review. The Florida Entomologist, 80 (2) DOI: 10.2307/3495552Reiskind, J. (1977). Ant-Mimicry in Panamanian Clubionid and Salticid Spiders. (Araneae: Clubionidae, Salticidae) Biotropica, 9 (1) DOI: 10.2307/2387854... Read more »
Cushing, P. (1997) Myrmecomorphy and Myrmecophily in Spiders: A Review. The Florida Entomologist, 80(2), 165. DOI: 10.2307/3495552
Reiskind, J. (1977) Ant-Mimicry in Panamanian Clubionid and Salticid Spiders (Araneae: Clubionidae, Salticidae). Biotropica, 9(1), 1. DOI: 10.2307/2387854
We usually associated cancer with environmental determinants, such as gamma ray or bisphenol A exposure, but two parasitic flukes that have been implicated in more than two-thirds of cases of a rare liver cancer in Southeast Asia and parts of East Asia may change how we think about carcinogens. The most fascinating aspect of these two parasites, Opisthorchis viverrini and Clonorchis senensis, is that human infection is directly associated with a culturally-specific method of cooking food, or in this case, not cooking it.... Read more »
Sriamporn, S., Pisani, P., Pipitgool, V., Suwanrungruang, K., Kamsa-ard, S., & Parkin, D. (2004) Prevalence of Opisthorchis viverrini infection and incidence of cholangiocarcinoma in Khon Kaen, Northeast Thailand. Tropical Medicine and International Health, 9(5), 588-594. DOI: 10.1111/j.1365-3156.2004.01234.x
Most science blog posts post a link to an academic article or two and discuss their merits or lack thereof. I am going to do something slightly different - I am linking to an entire special issue of a journal, with pdfs freely available online - and recommend that you do NOT waste any time reading any of it. All it really shows is a bunch of academics bickering over stuff that doesn't seem to make much of a difference. I imagine the DSM 5 PD workgroup meetings look something like this: South Korean politicians fighting Anyway, on to the articles. Out of all the changes being considered for the DSM 5, the personality disorder (PD) work group has proposed some of the most sweeping ones such as dropping 5 of the current PDs entirely and adding a dimensional component that somehow involved asssessing 6 trait domains and 37 facets for the remaining PDs. Not surprisingly, this has not gone over too well.The Journal of Personality Disorders has recently published a special issue (see link here with pdfs) that has invited articles by the DSM PD workgroup members and other commentaries in response to it. I repeat - don't bother reading any of it. Most of these articles are filled with jargon (SNAP, DAPP, NEO, DIPSI, HEXACO, OMGWTFBBQ), are quite boring, appear to be selective in whatever literature they cite, with quite a few of the authors increasing their self-citation count, while sniping at each other. Here's a brief rundown.In the first article, the workgroup (Andrew Skodol et al.) rehash their proposal, but note that "Feedback from the [DSM-5] website posting suggested that this system was too complicated, redundant with the full clinicians’ trait ratings, and unwieldy". Really? Nah! Say it ain't so! So their solution is to separate the 5 PD "types", from the "traits" and "facets" in the field trials, and somehow refine this system. How? It is not entirely clear.In the next article (Krueger et al.), the authors repeatedly talk about the "empirical structure of personality". Curiously, while there is some overlap in authors with the first one, they are not all identical. I suspect this means some sort of division among the PD workgroup members. Anyway, as the authors themselves acknowledge, the bulk of the evidence for their proposal uses a statistical technique called factor analysis, which is essentially based on a whole lot of correlations. Why this makes the authors' proposal or review any more "empirical" is pretty unclear to me. The authors also take some effort to delineate why Thomas Widiger's (another big name in the personality world) preferred model of personality may not be as "empirical" as theirs.The remaining articles are commentaries. Clarkin and Huprich's, and Zimmerman's, are worth skimming over, but don't really say anything that wasn't already known - i.e., the PD proposal is too complex to be clinically useful, and not really based on much evidence. Then, we have an article by the aforementioned Widiger, who hits back pretty hard at Lee Anna Clark and Robert Krueger (two other big names) for not using his preferred model of personality, and spends 13 pages or so picking apart the PD proposal and Clark and Krueger's work.This is followed by a couple of articles by Robert Bornstein (an expert on Dependent PD) and Elsa Ronningstam (an expert on Narcissistic PD). These two PDs are slated to be dropped. So, no prizes for guessing what these commentaries are about. And lastly, Joel Paris has an article on the use of endophenotypes for diagnosing PDs - though as he clearly notes, we don't have any yet (which DSM disorder does anyway?). In other words, an academic exercise in what might be useful if we ever find it.While I occasionally use some personality inventories in my work, most of my work doesn't involve the PDs, and as such, I have no strong ties to a 5-, 6-, or 18-factor model of personality. I picked up this special issue hoping for some sort of enlightenment on the PD proposal. Now, instead, I wish I could get back the hours I spent reading these articles. Skodol AE, Bender DS, Morey LC, Clark LA, Oldham JM, Alarcon RD, Krueger RF, Verheul R, Bell CC, & Siever LJ (2011). Personality Disorder Types Proposed for DSM-5. Journal of personality disorders, 25 (2), 136-69 PMID: 21466247Krueger RF, Eaton NR, Clark LA, Watson D, Markon KE, Derringer J, Skodol A, & Livesley WJ (2011). Deriving an Empirical Structure of Personality Pathology for DSM-5. Journal of personality disorders, 25 (2), 170-91 PMID: 21466248Clarkin JF, & Huprich SK (2011). Do DSM-5 Personality Disorder Proposals Meet Criteria for Clinical Utility? Journal of personality disorders, 25 (2), 192-205 PMID: 21466249Zimmerman M (2011). A Critique of the Proposed Prototype Rating System for Personality D... Read more »
Skodol AE, Bender DS, Morey LC, Clark LA, Oldham JM, Alarcon RD, Krueger RF, Verheul R, Bell CC, & Siever LJ. (2011) Personality Disorder Types Proposed for DSM-5. Journal of personality disorders, 25(2), 136-69. PMID: 21466247
Krueger RF, Eaton NR, Clark LA, Watson D, Markon KE, Derringer J, Skodol A, & Livesley WJ. (2011) Deriving an Empirical Structure of Personality Pathology for DSM-5. Journal of personality disorders, 25(2), 170-91. PMID: 21466248
Clarkin JF, & Huprich SK. (2011) Do DSM-5 Personality Disorder Proposals Meet Criteria for Clinical Utility?. Journal of personality disorders, 25(2), 192-205. PMID: 21466249
Zimmerman M. (2011) A Critique of the Proposed Prototype Rating System for Personality Disorders in DSM-5. Journal of personality disorders, 25(2), 206-21. PMID: 21466250
Widiger TA. (2011) The DSM-5 Dimensional Model of Personality Disorder: Rationale and Empirical Support. Journal of personality disorders, 25(2), 222-34. PMID: 21466251
Bornstein RF. (2011) Reconceptualizing Personality Pathology in DSM-5: Limitations in Evidence for Eliminating Dependent Personality Disorder and Other DSM-IV Syndromes. Journal of personality disorders, 25(2), 235-47. PMID: 21466252
Ronningstam E. (2011) Narcissistic Personality Disorder in DSM-V-In Support of Retaining a Significant Diagnosis. Journal of personality disorders, 25(2), 248-59. PMID: 21466253
Paris J. (2011) Endophenotypes and the diagnosis of personality disorders. Journal of personality disorders, 25(2), 260-8. PMID: 21466254
Another day, another proposed solution to the Fermi Paradox, which asks where are all the aliens if the skies are just filled with extraterrestrial empires. Yesterday, my good frienemies at the arXiv blog shone a light on a paper by a quantum theorist which tackles the possible interactions between alien species from evolutionary points of [...]... Read more »
Xenophobic exclusion has been ubiquitous throughout history. However, the explanation of such a phenomenon has been little understood. Interesting research conducted by Stapel and Lindenberg published in the latest Science has brought us closer to some answers. They found that people who are in a disordered environment (e.g. unclean subway station) exhibit greater discriminatory behavior (e.g. decision to sit further away from a black person compared to a white person). The authors suggest that when the brain faces disorder there is an equal need for order. One way to reach order is through stereotyping. It's the brain's way of making sense of the world. Too bad it doesn't work all the time.Stapel DA, & Lindenberg S (2011). Coping with chaos: how disordered contexts promote stereotyping and discrimination. Science (New York, N.Y.), 332 (6026), 251-3 PMID: 21474762... Read more »
Stapel DA, & Lindenberg S. (2011) Coping with chaos: how disordered contexts promote stereotyping and discrimination. Science (New York, N.Y.), 332(6026), 251-3. PMID: 21474762
Until recently, I did not fully appreciate fossil teeth. Their significance for identifying species and narrowing down the general diet of extinct animals was obvious, but I didn’t understand that teeth also hold intricate records of an individual animal’s life. Tiny pits and scratches on enamel can reveal what a creature was eating around the [...]... Read more »
Fisher, D. (2009) Paleobiology and extinction of proboscideans in the Great Lakes region of North America. American Megafaunal Extinctions at the End of the Pleistocene, 55-75. DOI: 10.1007/978-1-4020-8793-6_4
Medieval Venice was a trading empire, one of the busiest ports of the late medieval world. As a hub of commerce waves of plague visited and revisited Venice in 1348, 1462, 1485, 1506, 1575-1577, and 1630-1632 with the last two producing mortality rates around 30% of the population (Tran et al, 2011). As we all [...]... Read more »
Tran TN, Signoli M, Fozzati L, Aboudharam G, Raoult D, & Drancourt M. (2011) High throughput, multiplexed pathogen detection authenticates plague waves in medieval venice, Italy. PloS one, 6(3). PMID: 21423736
Foucault C, Brouqui P, & Raoult D. (2006) Bartonella quintana characteristics and clinical management. Emerging infectious diseases, 12(2), 217-23. PMID: 16494745
It’s my birthday! But how old am I? Well, that’s not such a straightforward question. Even a seemingly well-defined concept such as age can be affected by cultural factors
First, my age in years is a bit of an estimate of the actual amount of time I’ve been alive, due to leap-years etc. Second, a year is . . . → Read More: How old am I?... Read more »
Hill, M., Preston, S., Elo, I., & Rosenwaike, I. (1997) Age-Linked Institutions and Age Reporting among Older African Americans. Social Forces, 75(3), 1007. DOI: 10.2307/2580528
Hill, M., Preston, S., & Rosenwaike, I. (2000) Age Reporting among White Americans Aged 85 : Results of a Record Linkage Study. Demography, 37(2), 175. DOI: 10.2307/2648119
This sums up the basic conclusion of a new study on political orientation and brain structure by Ryota Kanai, Tom Feilden, Colin Firth and Geraint Rees in the journal Current Biology. Yes, that Colin Firth...Colin Firth's Speech during the 2011 Academy Awards. Firth won Best Actor for The King's Speech.Why are Colin Firth and Tom Feilden, both listed with BBC Radio 4 affiliations, authors on this paper? Let's go back to Tuesday, 28 December 2010 and two pieces that appeared on the BBC website.Politics: Brain or background?Science correspondent Tom Feilden: "What started out as a bit of fun has turned into quite a significant piece of science."Scientific research commissioned by this programme on behalf of our guest editor, Colin Firth, has shown a strong correlation between the structure of a person's brain and their political views. You can also listen to a brief audio clip of Feilden discussing the study at the link above. Firth actually commissioned Professor Geraint Rees at University College London to obtain structural MRI scans from two diametrically opposed politicians: conservative MP Alan Duncan (a member of the Conservative Party) and liberal MP Stephen Pound (a member of the Labour Party).Feilden then asks a question that is unanswerable from studying brain structure in adults: "Are political beliefs learnt, the product of experiences in our environment, or 'hard wired' in the brain?" Since a comparison of n=1 liberal versus n=1 conservative is not scientifically valid, Rees went back to a database of MRI scans from UCL students and asked these participants about their political beliefs. Feilden then discussed the results before the paper had been formally submitted for publication [according to the journal website, the paper was received by Current Biology on 11 January, 2011]. Briefly, he said that the gray matter of the anterior cingulate cortex was thicker among the liberal or left wing participants while the amygdala was much larger in those who identified as conservative or right wing."But is it cause and effect?" asks an interviewer. Rightfully so. Correlation does not equal causation. Then there's the claim that the structural brain variation means the political differences are "hard wired". The observed anatomical differences mean no such thing. Any experience will change the brain in some way, and repeated patterns of behavior, whether it's learning to juggle or voting conservative due to a certain set of core beliefs, can alter the brain. Nonetheless, we have the following headlineAre political beliefs hard-wired?Tom Feilden| 08:10 UK time, Tuesday, 28 December 2010"Give me the child until he's seven and I'll give you the man."It's clear from their motto that the Jesuits are firmly in the acquired camp when it comes to whether our political beliefs and values are learned or hard wired from birth: the product of experience rather than genetics.But is that true? ...along with the eventual admission:Although the results do show that political belief is reflected in the physical structure of the brain it's not clear which comes first. Whether the structure of the brain shapes political belief or political belief leads to the differential development of brain structure.All right, that was a media stunt, you say -- but how about the peer reviewed paper (Kanai et al., 2011)?A total of 90 healthy middle-class to upper-class participants (mean age = 23.5 yrs) underwent MRI scanning and [later?] filled out a very brief questionnaire on their political views:Participants were asked to indicate their political orientation on a five-point scale of very liberal (1), liberal (2), middle-of-the-road (3), conservative (4), and very conservative (5). ... Because none of the participants reported the scale corresponding to very conservative, the analyses were conducted using the scales of 1, 2, 3, and 4.If I'm not mistaken, no special effort was made to recruit very conservative participants, because the study was conceived after the MRIs were obtained.As reported by Feilden, being liberal was associated with a larger anterior cingulate whereas being conservative was associated with a larger right amygdala1 (see Figure 1 below).Figure 1 (Kanai et al., 2011). Individual Differences in Political Attitudes and Brain Structure. (A) Regions of the anterior cingulate where gray matter volume showed a correlation with political attitudes are shown overlaid on a T1-weighted MRI... A statistical threshold of p < 0.05, corrected for multiple comparisons, is used for display purposes. The correlation (left) between political attitudes and gray matter volume (right) averaged across the region of interest (error bars represent 1 standard error of the mean, and the displayed correlation and p values refer to the statistical parametric map presented on the right) is shown. (B) The right amygdala also showed a significant negative correlation between political attitudes and gray matter volume. Display conventions and warnings about overinterpreting the correlational plot (left) are identical to those for (A).The results were based on measurements of gray matter density in these two specific structures. How were they chosen? First, the anterior cingulate was selected based on the finding of Amodio et al. (2007) that......the amplitude of event-related potentials reflecting neural activity associated with conflict monitoring in the anterior cingulate cortex (ACC) is greater for liberals compared to conservatives. Thus, stronger liberalism is associated with increased sensitivity to cues for altering a habitual response pattern and with brain activity in anterior cingulate cortex.I had issues with this interpretation of the Amodio et al. study in 2007, which I will summarize here. One problem was attributing the observed results to political viewpoint and not to other factors. The study used EEG recordings, specifically event-related potentials. The ERP brain waves reflect electrophysiological activity recorded remotely from the scalp. While it's great for determining the temporal parameters of neural activity, it's not so great at determining where the activity is located in the brain.One brain wave of inter... Read more »
Ryota Kanai, Tom Feilden, Colin Firth, Geraint Rees. (2011) Political Orientations Are Correlated with Brain Structure in Young Adults. Current Biology. info:/10.1016/j.cub.2011.03.017
That title is awful I know but I'm tired. Cut me some slack :) I ran into a something that I have heard about before but assumed was rubbish and never really looked into it properly. A friend of mine insisted it was the case so I looked it up and I have to say, I was a little surprised.
So this is what cranberries look like. I never knew.
Cranberry juice is apparently very good at prevent urinary tract infection, particularly in women. There have been a few studies approaching it from different angles but, disappointingly, the studies all use different types of cranberry product, different doses and dosing techniques but despite all this the message seems to be pretty clear. Cranberries prevent urinary tract infections kicking in.
Before we can consider how this occurs its important to define what we are talking about. Urinary tract infections or UTIs are generally caused by a strain of Escherichia coli called Uropathogenic E. coli (UPEC) and it gets there by moving from the colon…ew. For this reason men rarely have to worry about them while they can be a chronic problem for women around the world, however the insertion of urinary catheters is a major risk factor for both genders. Clinical symptoms include burning sensation during urination and cloudy urine but these are only really evident once the bacteria have ascended the urethra into the bladder causing urethritis and cystitis respectively. If you want to feel real pain however let the little bastards work their way into your kidneys where kidney infection (or pyelonephritis) results in the above symptoms plus back pain and fever and the possibility of systemic spread.
So the first step in the infective process is generally stable colonisation of the colon. This step is often overlooked but without a source of UPEC it’s hard to get a proper infection going. The next step is invasion of the vaginal microbiota. Not an insignificant task since the vaginal niche is normally fully occupied by lactobacilli and other innocuous strains. Only once this has occurred can the UPEC ascend the urethra.
Having ascended the urethra the UPEC are not in the free and clear because the bladder and urethra have a formidable barrier to infection, the waterfall of flushing, cleansing urine that washes away all in its path. To overcome this UPEC have developed powerful adhesins, proteins used adherence of the bacterium to a surface and in this case specifically to the urinary epithelial tissue.
Adhesins are found in most pathogenic bacterial species but the array and strength of the UPEC adhesins is staggering. Among the most important adhesins produced by the UPEC are the pili. Pili are hair-like structures on the bacterial surface that are often capped with sticky (in the molecular sense) ends that facilitate adhesion. Importantly for UPEC possessing three different sticky caps (S, P and Type 1 pili) increases the chances of binding.
The S pili tend to be more important for adhesion outside of the gentio-urinary tract and so may play a part in systemic spread. In the urine however these pili bind the mannose filled protein uromodulin. Because of this S pili are called mannose sensitive pili and its thought that the ability to bind uromodulin, the most abundant protein in urine, possibly results in bacterial clumping and this allows a better opportunity for the P and Type 1 pili to do their thing. These two pili are responsible for the binding in the urethra and bladder.
Initially the Type 1 pili bind mannose sugars on the surface of the bladder cells allowing the bacteria to get some traction on the bladder/urethra walls before the P pili bind to a different sugar group to cement the interaction. The ability of P pili to bind non-mannose sugars has earned them the alternative title mannose resistant pili whereas type 1 pili are grouped with the mannose sensitive S pili.
The pili are the hairy bits on the picture of E. coli. The paper this pic is from is referenced at the bottom.
Once adhered to the host surface the UPEC can invade the epithelial cells but the bladder’s defence against this is to kick those invaded cells into the urine. A good defence strategy but it may contribute to tissue damage in the urinary tract when infections are recurrent. Also it seems some bacteria can prevent this expulsion of the cell they have invaded and in doing so remain as a reservoir of infection out of the way of the immune system and most antibiotic treatments.
Invasion does not always occur and instead some UPEC strains are able to release toxins directly onto the host epithelial surface due to the close interaction between bacterium and host. These toxins, as well as one of my boss’s favourite little molecules lipopolysaccharide (LPS) cause the inflammation that goes with the UTI.
So that’s the UTI side of things but where does Cranberry juice come into this story?
Cranberries (Vaccinium macrocarpon if you don’t mind) together with blueberries and Concord grapes constitute the only native fruit species to the US and Canada. Bet you didn’t know that, or maybe you did but I didn’t. In any case often the best way to work out what the native flora is capable of you have to look back to the indigenous peoples and, surprise surprise, Native Americans have known about and utilised the medicinal properties of cranberries for many years. Commonly used in different preparations to treat blood disorders, stomach issues, liver trouble and fevers.
By the 1880’s people were trying to work out what was doing what with cranberries and some German researchers found benzoic acid in cranberries. Then as now it was known to be a potent antiseptic and was included in a number of medicines and topical anti-bacteria treatments. This observation set researchers down the wrong path from the get go as the real power of cranberries lies in other activities of other compounds.
Continuing research into the antibacterial properties of cranberries found the benzoic acid was converted to hippuric acid, another antibacterial agent that also has a role in acidifying the urine. Everyone thought they were onto a winner. A powerful antibacterial compound excreted in the urine because you ate some cranberries. This is open and closed right? Well…
Could I be any clearer... Read more »
BODEL PT, COTRAN R, & KASS EH. (1959) Cranberry juice and the antibacterial action of hippuric acid. The Journal of laboratory and clinical medicine, 881-8. PMID: 13801916
Sobota AE. (1984) Inhibition of bacterial adherence by cranberry juice: potential use for the treatment of urinary tract infections. The Journal of urology, 131(5), 1013-6. PMID: 6368872
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