| NANYANG TECHNOLOGICAL UNIVERSITY |
 Zinc oxide can be found in many consumer products, including creams and ointments. Image: Dabblelicious, Flickr CC-licensed A study led by a group of Nanyang Technological University (NTU) researchers has found that a chemical commonly used in consumer products can potentially cause cancer. The chemical, zinc oxide, is used to absorb harmful ultra violet light. But when it is turned into nano-sized particles, they are able to enter human cells and may damage the user's DNA. This in turn activates a protein called p53, whose duty is to prevent damaged cells from multiplying and becoming cancerous. However, cells that lack p53 or do not produce enough functional p53 may instead develop into cancerous cells when they come into contact with zinc oxide nanoparticles. The study is led by Assistant Professor Joachim Loo, 34, and Assistant Professor Ng Kee Woei, 37, from NTU’s School of Materials Science and Engineering. They worked with Assistant Professor David Leong, 38, from the Department of Chemical and Biomolecular Engineering, National University of Singapore, a joint senior author of this research paper. The findings suggest that companies may need to reassess the health impact of nano-sized zinc xxide particles used in everyday products. More studies are also needed on the use and concentration levels of nanomaterials in consumer products, how often a consumer uses them and in what quantities. “Currently there is a lack of information about the risks of the nanomaterials used in consumer products and what they can pose to the human body. This study points to the need for further research in this area and we hope to work with the relevant authorities on this,” said Asst Prof Loo. The groundbreaking research findings were published in this month’s edition of Biomaterials, one of the world’s top journals in the field of biomaterials research. The breakthrough also validated efforts by Asst Prof Loo and Asst Prof Ng to pioneer a research group in the emerging field of nanotoxicology, which is still very much in its infancy throughout the world. Nanotoxicology studies materials to see if they are toxic or harmful when they are turned into nano-sized particles. This is because nanomaterials usually have very different properties when compared to when the materials are of a larger size. Asst Prof Ng said the team will carry out further research as the DNA damage brought about by nano-sized zinc oxide particles is currently a result of an unknown mechanism. But what is clear is that besides causing DNA damage, nanoparticles can also cause other harmful effects when used in high doses. “From our studies, we found that nanoparticles can also increase stress levels in cells, cause inflammation or simply kill cells,” said Asst Prof Ng who added that apart from finding out the cellular mechanism, more focused research is also expected to ascertain the physiological effects and damage that nano-sized zinc oxide particles can cause. Asst Prof Loo pointed out that besides enhancing the understanding of the potential risks of using nanomaterials, advancements in nanotoxicology research will also help scientists put nanomaterials to good use in biomedical applications. For example, although killing cells in our bodies is typically undesirable, this becomes a positive outcome if it can be effectively directed towards cancer cells in the body. At the same time, the team is also studying how nanomaterials can be “re-designed” to pose a lesser risk to humans, yet still possess the desired beneficial properties. This research discovery is one of the latest in a series of biomedical breakthroughs by NTU in healthcare. Future healthcare is one of NTU’s Five Peaks of Excellence with which the university aims to make its mark globally under the NTU 2015 five-year strategic plan. The other four peaks are sustainable earth, new media, the best of the East and West, and innovation. Moving forward, the team hopes to work with existing and new collaborative partners, within and outside of Singapore, to orchestrate a more concerted effort towards the advancement of the fledgling field of nanotoxicology here, with the aim of helping regulatory bodies in Singapore formulate guidelines to protect consumer interests. The research team would also like to work with the European Union to uncover the risks involving nanomaterials and how these materials should be regulated before they are made commercially available. Asst Prof Joachim Loo, who received his Bachelor and Doctorate degrees from NTU, was the only Singaporean representative in a recent nanotechnology workshop held in Europe. At the workshop, it was agreed that research collaborations in nanotoxicology between EU and South-east Asia should be increased. Editor's Note: Original news release can be found here. |
Thursday, December 1, 2011
‘Everyday’ chemical may cause cancer
The Pill linked to prostate cancer
| MARION LOPEZ, SCIENCENETWORK WA |
 "Pills in use today can potentially act as EDCs as they frequently contain high doses of ethinyloestradiol, which is excreted in urine without degradation.” Image: anqa, Flickr CC-licensed An international study published in BMJ Open has recently suggested the existence of a causal link between the use of the contraceptive pill and the increase incidence of prostate cancer, due to men’s abnormal exposure to low levels of oestrogen in the environment. Prostate cancer is the most common male malignancy in the Western world and its risk factors other than age, ethnicity and family history still remain ill-defined. Although the study is ecological (i.e. a study where the unit of analysis is a population rather than an individual) and cannot ascertain the results, researchers have put forward the hypothesis that oestrogen by-products could be passed via urine into the environment in general or drinking water, thus exposing the population at large. “The last two decades have witnessed growing scientific concerns and public debate over the potential adverse effects that may result from exposure to a group of chemicals [found in the contraceptive pill] that have the potential to alter the normal functioning of the endocrine system in wildlife and humans,” say researchers. “These chemicals are typically known as endocrine disturbing compounds (EDCs). “Temporal increases in the incidence of certain cancers (breast, endometrial, thyroid, testis and prostate) in hormonally sensitive tissues in many parts of the industrialised world are often cited as evidence that widespread exposure of the general population to EDCs has had adverse impacts on human health. “Pills in use today can potentially act as EDCs as they frequently contain high doses of ethinyloestradiol, which is excreted in urine without degradation.” CEO of the Prostate Cancer Foundation Dr Anthony Lowe believes the study is interesting but needs to be viewed with caution. “It is well known that prostate cancer is strongly associated with male hormones and a number of recent studies have suggested a possible association with female hormones. “However, what the study shows is that countries where there is a high use of oral contraceptives have a high incidence of prostate cancer. It does not demonstrate a causal link. “It may be that countries where there is a high use of oral contraceptives share other factors e.g. western diet and lifestyle, that are a risk factor for prostate cancer. “More work and a different type of study are needed to demonstrate the link.” Although the causes remain unclear, awareness and advocacy of the issue among the general public are strong. Nearly 141,000 Australians have registered for Movember and raised about $17,500,000 for research this year. Leader of the Prostate Cancer Support Group Pam Sandoe is pleased with people’s enthusiasm. “It’s a great fund raiser and we are more than delighted with this great men's health initiative.” Editor's Note: Original news release can be found here. |
How to Treat AIDS
this video is an information resource to be used for educational purposes only. The information is not intended to serve as a substitute for professional medical advice and we recommend that all decisions about your treatment or products you wish to use should be discussed thoroughly and frankly with your doctor.
HIV, or the Human Immunodeficiency Virus, is a serious infection that does not have a cure. According to the World Health Organization, the virus systematically weakens the immune system by destroying T and CD4 cells, which allows opportunistic infections to cause serious health consequences. The virus manifests into full blown AIDS once specific complications such as tuberculosis are diagnosed according to the Centers for Disease Control and Prevention.
Treating AIDS requires routine supervision by a medical doctor, preferably an infectious disease specialist. Your doctor may place you on a treatment plan that includes an antiretroviral therapy regimen. The National Institutes of Health says to stick to the medication schedule and obtain routine monitoring of your CD4 counts every 3 to 6 months. This monitoring is needed to ensure the effectiveness of your drug combination.
Make an active contribution to staying well by focusing on a healthy lifestyle. Base your diet on fresh vegetables, fruits, lean proteins and whole grains. The Mayo Clinic suggests eating good foods as a method of supporting your immune system and providing a higher level of energy. The Mayo Clinic also advises to avoid eating unpasteurized dairy items, raw foods or eggs and insure all meats are cooked until there are no traces of pink.
In addition to healthy food selections, the Mayo Clinic suggests incorporating an exercise regimen and making your living space as germ and virus-free as possible. Consider getting rid of any cats or reptiles you have as pets. These animals can cause infections such as salmonella or toxoplasmosis, which can be detrimental to HIV-positive or AIDS patients according to the Mayo Clinic.
The Mayo Clinic also suggests some dietary supplements that may be helpful. Coenzyme Q10 may help increase the number of CD4 cells in your system. Whey protein may help minimize diarrhea, increase CD4 counts and may help you gain weight. Fish oil supplements may help lower cholesterol counts increased due to some anti-AIDS drugs.
HIV, or the Human Immunodeficiency Virus, is a serious infection that does not have a cure. According to the World Health Organization, the virus systematically weakens the immune system by destroying T and CD4 cells, which allows opportunistic infections to cause serious health consequences. The virus manifests into full blown AIDS once specific complications such as tuberculosis are diagnosed according to the Centers for Disease Control and Prevention.
Treating AIDS requires routine supervision by a medical doctor, preferably an infectious disease specialist. Your doctor may place you on a treatment plan that includes an antiretroviral therapy regimen. The National Institutes of Health says to stick to the medication schedule and obtain routine monitoring of your CD4 counts every 3 to 6 months. This monitoring is needed to ensure the effectiveness of your drug combination.
Make an active contribution to staying well by focusing on a healthy lifestyle. Base your diet on fresh vegetables, fruits, lean proteins and whole grains. The Mayo Clinic suggests eating good foods as a method of supporting your immune system and providing a higher level of energy. The Mayo Clinic also advises to avoid eating unpasteurized dairy items, raw foods or eggs and insure all meats are cooked until there are no traces of pink.
In addition to healthy food selections, the Mayo Clinic suggests incorporating an exercise regimen and making your living space as germ and virus-free as possible. Consider getting rid of any cats or reptiles you have as pets. These animals can cause infections such as salmonella or toxoplasmosis, which can be detrimental to HIV-positive or AIDS patients according to the Mayo Clinic.
The Mayo Clinic also suggests some dietary supplements that may be helpful. Coenzyme Q10 may help increase the number of CD4 cells in your system. Whey protein may help minimize diarrhea, increase CD4 counts and may help you gain weight. Fish oil supplements may help lower cholesterol counts increased due to some anti-AIDS drugs.
The communicative brain
Functional neuroimaging of the human brain. Credit: William Marslen-Wilson and Lorraine Tyler
The ability to communicate using language is fundamental to the distinctive and remarkable success of the modern human. It is this capacity that separates us most decisively from our primate cousins, despite all that we have in common across species as intelligent social primates.
A major challenge for the cognitive neurosciences is to understand this relationship: what is the neurobiological context in which human language and communication have emerged, and what are the special human properties that make language itself possible?
For the past 150 years, scientific thinking about this relationship has been dominated by the concept of a single, central language system built around the brain’s left hemisphere. Pioneering 19th-century neurologists Paul Broca and Carl Wernicke noticed that patients with left hemisphere brain damage had difficulties with language comprehension and language production. Two areas of the left frontal and temporal lobes, Broca’s area and Wernicke’s area, and the bundle of nerve fibres connecting them, were identified as critical for speaking and understanding language.
Recent research in our laboratories suggests major limitations to this classic approach to language and the brain. The Broca–Wernicke concept captures one important aspect of the neural language system – the key role of the left hemisphere network – but it obscures another, equally important one. This is the role of bi-hemispheric systems and processes, whereby both left and right hemispheres work together to provide the fundamental underpinnings for human communicative processes.
A more fruitful approach to human language and communication will require a dual neurobiological framework in which these capacities are supported by two intersecting but evolutionarily and functionally distinguishable subsystems. The historical failure to make this separation has, we suggest, severely undermined scientific attempts to understand language, both as a neurocognitive phenomenon in the modern human, and in terms of its evolutionary and neurobiological context.
Dual systems
A strong evolutionary continuity between humans and our primate relatives is provided by a distributed, bi-hemispheric set of capacities that support the dynamic interpretation of visual and auditory signals in the service of social communication. These capacities have been the object of intensive study in monkeys and apes, and there is good evidence that their basic architecture underpins related communicative functions in the human.
In the context of human language comprehension, the bi-hemispheric systems support the ability not only to identify the words a speaker is producing – typically by integrating auditory and visual cues in face-to-face interaction – but also to make sense of these word-meanings in the general context of the listener’s knowledge of the world and of the specific context of speaking.
Where we see divergence between humans and other primates is in the domain of grammatical (or syntactic) function. Primate communication systems are not remotely comparable to human language in their expressive capacities. Human language is much more than a set of signs that stand for things. It constitutes a powerful and flexible set of grammatical devices for organising the flow of linguistic information and its interpretation, allowing us to represent and combine abstract linguistic elements, where these elements convey not only meaning but also the subtle structural cues that indicate how these elements are linked together.
It is the fronto-temporal network of regions in the left hemisphere that mediates these core grammatical functions in humans. This is a network that differs neuroanatomically from those of the brains of other primates, showing substantial increases in size, complexity and connectivity.
Although it’s not yet understood just how these evolutionary changes in the left hemisphere provide the neural substrate on which grammatical functions depend, it is clear that they are essential. When the left hemisphere system is damaged, the parallel right hemisphere regions cannot take over these functions, even when damage is sustained early in childhood.
Critically, however, the left hemisphere system that has emerged in humans neither replaces nor displaces the bi-hemispheric system for social communication and action found in both humans and other primates. It interacts and combines with it to create a co-ordinated process of linguistically guided communication and social interaction.
Functional separability
The most direct evidence for a dual system approach is the ability to separate these systems in the modern human. Using a combination of behavioural and neuroimaging techniques, we have been able to demonstrate this both in patients with left hemisphere brain damage and in unimpaired young adults.
In the research with patients (conducted with Dr Paul Wright in the Department of Experimental Psychology and Dr. Emmanuel Stamatakis in the Division of Anaesthesia) we focus on the comprehension of spoken words and spoken sentences. In initial testing, patients perform classic measures of syntactic function, where they match different spoken sentences to sets of pictures. Shown three pictures – a woman pushing a girl, a girl pushing a woman and a woman teaching a girl – patients will correctly match the sentence ‘The woman pushed the girl’ to the first picture but will incorrectly match the passive sentence ‘The woman is being pushed by the girl’ to the same picture. The second sentence requires the use of syntactic cues to extract the right meaning – just using the order of words is not sufficient.
These behavioural tests of syntactic impairment are linked, in the same patients, to their performance in the neuroimaging laboratory, where they hear sentences that vary in their syntactic demands, and where the precise extent of the injury to their brains can be mapped out. When we put these different sources of information together, we see that damage to the left hemisphere system progressively impairs the syntactic aspects of language processing – the more damage, the worse the performance.
Critically, however, the amount of left hemisphere damage, and the extent to which it involves the key fronto-temporal circuit, does not affect the patients’ ability to identify the words being spoken or to understand the messages being communicated – so long as syntactic cues are not required to do so. These capacities are supported bi-hemispherically, and can remain relatively intact even in the face of massive left hemisphere damage.
In work carried out with Dr. Mirjana Bozic, then based at the Medical Research Council (MRC) Cognition and Brain Sciences Unit in Cambridge, we have been able to delineate these systems in the undamaged brain, using functional neuroimaging to tease out the different processing regions that are engaged by speech inputs with different properties.
Listeners hear either words that are specifically linguistically complex (words like played, which have the grammatical inflection ‘ed’), or words that make more general demands on the language processing system (words like ramp, which have another word, ram, embedded in them). Using an analysis technique that identifies the separate dimensions of the brain’s response to these sets of words, we see that the linguistically complex words activate a response component that is restricted to the left fronto-temporal region. By contrast, words that are perceptually complex, due to increased competition between the whole word and the embedded word, activate a strongly bi-hemispheric set of regions, partially overlapping with the linguistic component. Even in the intact brain, therefore, we can see the dynamic allocation of processing resources across the two systems, as a function of their joint roles in the communicative process.
Implications
A dual systems account of the ‘communicative brain’ is likely to have important and illuminating consequences for the sciences of language and its disorders.
In the context of left hemisphere brain damage we can better appreciate – and build upon for rehabilitation – the substantial bi-hemispheric communicative capacities the patient may still possess. In first- and second-language acquisition, we can better understand the learning trajectories that lead to language proficiency in terms of the relative contributions of these two aspects of communicative function.
The approach also provides a new perspective on the variation between languages, where different languages may load more or less heavily on the different computational resources made available by the two systems. Most importantly, it enables us to clarify and focus the core issues for a neurobiological account of language and communication, a scientific domain clouded by ideology and inconsistency.
Provided by University of Cambridge
"The communicative brain." November 30th, 2011. http://medicalxpress.com/news/2011-11-brain_1.html
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Robert Karl Stonjek
Robert Karl Stonjek
Brain training exercises more effective at improving cognitive function than crossword puzzles, study says
A new study shows that doing brain training exercises is more effective at improving cognitive function than performing knowledge games, like crossword puzzles. This is the preliminary analysis of the results from Iowa Healthy and Active Minds Study (IHAMS) presented last week at Gerontological Society of America (GSA) 64th Annual Scientific Meeting in Boston.
The study will be completed in January and its interim results were published this week in BMJ Open. It found that 10 hours of using brain training software improved cognitive function on several standard neuropsychological tests. This is the case whether used in a supervised clinical setting, or self-administered at home. This study included younger (ages 50-64) and older (ages 65-87) participants, and the brain training software worked equally well for both groups.
IHAMS is a follow up to Advanced Cognitive Training for Independent and Vital Elderly (ACTIVE) study funded by National Institutes of Health (NIH). In past medical journal articles the ACTIVE study showed brain plasticity software improved visual processing speed, among other factors. IHAMS was designed to overcome limitations in the ACTIVE study by including younger participants.
Early results are that participants who used brain training software significantly improved their cognitive capabilities on several standard neuropsychological tests of cognitive functioning than did participants who trained on crossword puzzles. The improvements in cognitive function were the same whether the brain exercises were done in the monitored clinical setting or in the participant's home. These positive changes were observed within 8 weeks, and were sustained over 12 months. The improvements for younger participants were just as large as those for the older participants, indicating benefits to beginning brain training early.
"There's been debate in the scientific community regarding how well brain training works versus other recreational mental activities, such as learning a new language or doing crossword puzzles," said Dr. Fred Wolinsky, John W. Colloton Chair in Health Management and Policy, University of Iowa. "This study clearly demonstrates that specially constructed exercises for brain fitness – such as the speed-of-processing core of DriveSharp and InSight – work, and are more effective at improving cognitive function than games or recreational activities."
The Road Tour brain training exercise used in IHAMS is one of five exercises in Posit Science InSight brain fitness software, and part of DriveSharp, a shorter cognitive training program focused around driving safety.
More information: Paper online: http://bmjopen.bmj … e000225.full
Provided by Posit Science
"Brain training exercises more effective at improving cognitive function than crossword puzzles, study says." November 30th, 2011.http://medicalxpress.com/news/2011-11-brain-effective-cognitive-function-crossword.html
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Robert Karl Stonjek
Robert Karl Stonjek
New research distinguishes roles of conscious and subconscious awareness
What distinguishes information processing with conscious awareness from processing occurring without awareness? And, is there any role for conscious awareness in information processing, or is it just a byproduct, like the steam from the chimney of a train engine, which is significant, but has no functional role?
These questions - which have long puzzled psychologists, philosophers, and neurobiologists - were recently addressed in a study by Hebrew University of Jerusalem researchers and published by the journal Psychological Science.
The study was headed by Prof. Leon Deouell from the Hebrew University's Edmond and Lily Safra Center for Brain Sciences (ELSC) and Department of Psychology and Prof. Dominique Lamy from the Department of Psychology at Tel Aviv University, and conducted by research student Liad Mudirk of Tel Aviv University with collaboration of research student Assaf Breska from the Hebrew University.
We are not consciously aware of most of the input that hits upon our sensory systems. Yet subjectively, conscious awareness dominates our mental activity. "One of the dominant theories in cognitive sciences and psychology posits that parts of the information perceived without awareness may be processed to a certain extent," says Prof. Deouell. "Yet to bind the different parts of a complex input into something meaningful and coherent requires conscious awareness.
To test this theory, the research team ran a study in which they presented participants with pictures of natural scenes including some human action, like a picture of basketball players jumping to reach a ball.
In other tests, the same scenes were presented -- except that the central object was replaced by another, unlikely object. For example, the basketball was replaced by a watermelon.
The participants viewed the pictures through a mirror stereoscope, a simple device that allowed the research team to present the pictures to only one eye. At the same time, the other eye viewed rapidly flickering patterns of colors which drew the subjects' attention, so that the participants were not aware for many seconds that anything was presented to their other eye. This allowed the researchers to measure how long it takes normal and unusual scenes to "win the competition" against the flickering pattern and break into awareness.
"We found that participants became aware of the unusual scenes earlier than to the usual scenes," commented Deouell. "The conclusion was that even before the participants were aware of the existence of the picture, the semantic relationships between parts of the scene were interpreted."
The study shows that, counter to previous theories, integration is not the prerogative of conscious awareness but is achieved even without awareness. When and why then do we need conscious awareness?
The findings of this research suggest that when the results of the integration between parts of the input are incompatible with expectations or prior knowledge, awareness is required in order to account for the conundrum. Thus, the study expands the realm of unaware processes, yet shows that conscious awareness is not a meaningful luxury - it allows us to deal with novel and unexpected situations.
Provided by Hebrew University of Jerusalem
"New research distinguishes roles of conscious and subconscious awareness." November 30th, 2011. http://medicalxpress.com/news/2011-11-distinguishes-roles-conscious-subconscious-awareness.html
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Robert Karl Stonjek
Robert Karl Stonjek
New research proves color is not a black and white issue
Scientists at the University of Hull have found that some people have the ability to hallucinate colours at will – even without the help of hypnosis.
The study, published this week in the journal Consciousness and Cognition, was carried out in the Department of Psychology at the University of Hull. It focused on a group of people that had shown themselves to be 'highly suggestible' in hypnosis.
The subjects were asked to look at a series of monochrome patterns and to see colour in them. They were tested under hypnosis and without hypnosis and both times reported that they were able to see colours.
Individuals' reactions to the patterns were also captured using an MRI scanner, which enabled the researchers to monitor differences in brain activity between the suggestible and non-suggestible subjects. The results of the research, showed significant changes in brain activity in areas of the brain responsible for visual perception among the suggestible subjects only.
Professor Giuliana Mazzoni, lead researcher on the project says: "These are very talented people. They can change their perception and experience of the world in ways that the rest of us cannot."
The ability to change experience at will can be very useful. Research has shown that hypnotic suggestions can be used to block pain and increase the effectiveness of psychotherapy.
It has always been assumed that hypnosis was needed for these effects to occur, but the new study suggests that this is not true. Although hypnosis does seem to heighten the subjects' ability to see colour, the suggestible subjects were also able to see colours and change their brain activity even without the help of hypnosis.
The MRI scans also showed clearly that although it was not necessary for the subjects to be under hypnosis to be able to perceive colours in the tests, it was evident that hypnosis increased the ability of the subjects to experience these effects.
Dr William McGeown, who also contributed to the study, says: "Many people are afraid of hypnosis, although it appears to be very effective in helping with certain medical interventions, particularly pain control. The work we have been doing shows that certain people may benefit from suggestion without the need for hypnosis."
The study, which was partially funded by the BBC, used a control group formed of less suggestible people, or people less likely to respond to hypnosis. It was found that this group of people were not able to hallucinate colour and, again, these reported results were supported by MRI scans.
Provided by University of Hull
"New research proves color is not a black and white issue." November 30th, 2011. http://medicalxpress.com/news/2011-11-black-white-issue.html
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Robert Karl Stonjek
Robert Karl Stonjek
Banishing consciousness: the mystery of anaesthesia
- by Linda Geddes
(Image: George Doyle/Stockbyte/Getty)I WALK into the operating theatre feeling vulnerable in a draughty gown and surgical stockings. Two anaesthetists in green scrubs tell me to stash my belongings under the trolley and lie down. "Can we get you something to drink from the bar?" they joke, as one deftly slides a needle into my left hand.
I smile weakly and ask for a gin and tonic. None appears, of course, but I begin to feel light-headed, as if I really had just knocked back a stiff drink. I glance at the clock, which reads 10.10 am, and notice my hand is feeling cold. Then, nothing.
I have had two operations under general anaesthetic this year. On both occasions I awoke with no memory of what had passed between the feeling of mild wooziness and waking up in a different room. Both times I was told that the anaesthetic would make me feel drowsy, I would go to sleep, and when I woke up it would all be over.
What they didn't tell me was how the drugs would send me into the realms of oblivion. They couldn't. The truth is, no one knows.
The development of general anaesthesia has transformed surgery from a horrific ordeal into a gentle slumber. It is one of the commonest medical procedures in the world, yet we still don't know how the drugs work. Perhaps this isn't surprising: we still don't understand consciousness, so how can we comprehend its disappearance?
That is starting to change, however, with the development of new techniques for imaging the brain or recording its electrical activity during anaesthesia. "In the past five years there has been an explosion of studies, both in terms of consciousness, but also how anaesthetics might interrupt consciousness and what they teach us about it," says George Mashour, an anaesthetist at the University of Michigan in Ann Arbor. "We're at the dawn of a golden era."
Consciousness has long been one of the great mysteries of life, the universe and everything. It is something experienced by every one of us, yet we cannot even agree on how to define it. How does the small sac of jelly that is our brain take raw data about the world and transform it into the wondrous sensation of being alive? Even our increasingly sophisticated technology for peering inside the brain has, disappointingly, failed to reveal a structure that could be the seat of consciousness.Altered consciousness doesn't only happen under a general anaesthetic of course - it occurs whenever we drop off to sleep, or if we are unlucky enough to be whacked on the head. But anaesthetics do allow neuroscientists to manipulate our consciousness safely, reversibly and with exquisite precision.
It was a Japanese surgeon who performed the first known surgery under anaesthetic, in 1804, using a mixture of potent herbs. In the west, the first operation under general anaesthetic took place at Massachusetts General Hospital in 1846. A flask of sulphuric ether was held close to the patient's face until he fell unconscious.
Since then a slew of chemicals have been co-opted to serve as anaesthetics, some inhaled, like ether, and some injected. The people who gained expertise in administering these agents developed into their own medical specialty. Although long overshadowed by the surgeons who patch you up, the humble "gas man" does just as important a job, holding you in the twilight between life and death.
Consciousness may often be thought of as an all-or-nothing quality - either you're awake or you're not - but as I experienced, there are different levels of anaesthesia (see diagram) . "The process of going into and out of general anaesthesia isn't like flipping a light switch," says Mashour. "It's more akin to a dimmer switch."
A typical subject first experiences a state similar to drunkenness, which they may or may not be able to recall later, before falling unconscious, which is usually defined as failing to move in response to commands. As they progress deeper into the twilight zone, they now fail to respond to even the penetration of a scalpel - which is the point of the exercise, after all - and at the deepest levels may need artificial help with breathing.
These days anaesthesia is usually started off with injection of a drug called propofol, which gives a rapid and smooth transition to unconsciousness, as happened with me. (This is also what Michael Jackson was allegedly using as a sleeping aid, with such unfortunate consequences.) Unless the operation is only meant to take a few minutes, an inhaled anaesthetic, such as isoflurane, is then usually added to give better minute-by-minute control of the depth of anaesthesia.
Lock and key
So what do we know about how anaesthetics work? Since they were first discovered, one of the big mysteries has been how the members of such a diverse group of chemicals can all result in the loss of consciousness. Other drugs work by binding to receptor molecules in the body, usually proteins, in a way that relies on the drug and receptor fitting snugly together like a key in a lock. Yet the long list of anaesthetic agents ranges from large complex molecules such as barbiturates or steroids, to the inert gas xenon, which exists as mere atoms. How could they all fit the same lock?
For a long time there was great interest in the fact that the potency of anaesthetics correlates strikingly with how well they dissolve in olive oil. The popular "lipid theory" said that instead of binding to specific protein receptors, the anaesthetic physically disrupted the fatty membranes of nerve cells, causing them to malfunction.
In the 1980s, though, experiments in test tubes showed that anaesthetics could bind to proteins in the absence of cell membranes. Since then, protein receptors have been found for many anaesthetics. Propofol, for instance, binds to receptors on nerve cells that normally respond to a chemical messenger called GABA. Presumably the solubility of anaesthetics in oil affects how easily they reach the receptors bound in the fatty membrane.
But that solves only a small part of the mystery. We still don't know how this binding affects nerve cells, and which neural networks they feed into. "If you look at the brain under both xenon and propofol anaesthesia, there are striking similarities," says Nick Franks of Imperial College London, who overturned the lipid theory in the 1980s. "They must be triggering some common neuronal change and that's the big mystery."
Many anaesthetics are thought to work by making it harder for neurons to fire, but this can have different effects on brain function, depending on which neurons are being blocked. So brain-imaging techniques such as functional MRI scanning, which tracks changes in blood flow to different areas of the brain, are being used to see which regions of the brain are affected by anaesthetics. Such studies have been successful in revealing several areas that are deactivated by most anaesthetics. Unfortunately, so many regions have been implicated it is hard to know which, if any, are the root cause of loss of consciousness.
But is it even realistic to expect to find a discrete site or sites acting as the mind's "light switch"? Not according to a leading theory of consciousness that has gained ground in the past decade, which states that consciousness is a more widely distributed phenomenon. In this "global workspace
The idea has recently gained support from recordings of the brain's electrical activity using electroencephalograph (EEG) sensors on the scalp, as people are given anaesthesia. This has shown that as consciousness fades there is a loss of synchrony between different areas of the cortex - the outermost layer of the brain important in attention, awareness, thought and memory (Science, vol 322, p 876
This process has also been visualised using fMRI scans. Steven Laureys
A team led by Andreas Engel
We know that upon entering the brain, sensory stimuli first activate a region called the primary sensory cortex, which runs like a headband from ear to ear. Then further networks are activated, including frontal regions involved in controlling behaviour, and temporal regions towards the base of the brain that are important for memory storage.
Engel found that at the deepest levels of anaesthesia, the primary sensory cortex was the only region to respond to the electric shock. "Long-distance communication seems to be blocked, so the brain cannot build the global workspace," says Engel, who presented the work at last year's Society for Neuroscience meeting in San Diego. "It's like the message is reaching the mailbox, but no one is picking it up."
What could be causing the blockage? Engel has unpublished EEG data suggesting that propofol interferes with communication between the primary sensory cortex and other brain regions by causing abnormally strong synchrony between them. "It's not just shutting things down. The communication has changed," he says. "If too many neurons fire in a strongly synchronised rhythm, there is no room for exchange of specific messages."
The communication between the different regions of the cortex is not just one way; there is both forward and backward signalling between the different areas. EEG studies on anaesthetised animals suggest it is the backwards signal between these areas that is lost when they are knocked out.
Last month, Mashour's group published EEG work showing this to be important in people too. Both propofol and the inhaled anaesthetic sevoflurane inhibited the transmission of feedback signals from the frontal cortex in anaesthetised surgical patients. The backwards signals recovered at the same time as consciousness returned (PLoS One, DOI:10.1371/journal.pone.0025155
Similar findings are coming in from studies of people in a coma or persistent vegetative state (PVS), who may open their eyes in a sleep-wake cycle, although remain unresponsive. Laureys, for example, has seen a similar breakdown in communication between different cortical areas in people in a coma. "Anaesthesia is a pharmacologically induced coma," he says. "That same breakdown in global neuronal workspace is occurring."
Many believe that studying anaesthesia will shed light on disorders of consciousness such as coma. "Anaesthesia studies are probably the best tools we have for understanding consciousness in health and disease," says Adrian Owen
Owen and others have previously shown that people in a PVS respond to speech with electrical activity in their brain. More recently he did the same experiment in people progressively anaesthetised with propofol. Even when heavily sedated, their brains responded to speech. But closer inspection revealed that those parts of the brain that decode the meaning of speech had indeed switched off, prompting a rethink of what was happening in people with PVS (Proceedings of the National Academy of Sciences, vol 104, p 16032
As for my own journey back from the void, the first I remember is a different clock telling me that it is 10.45 am. Thirty-five minutes have elapsed since my last memory - time that I can't remember, and probably never will.
"Welcome back," says a nurse sitting by my bed. I drift in and out of awareness for a further undefined period, then another nurse wheels me back to the ward, and offers me a cup of tea. As the shroud of darkness begins to lift, I contemplate what has just happened. While I have been asleep, a team of people have rolled me over, cut me open, and rummaged about inside my body - and I don't remember any of it. For a brief period of time "I" had simply ceased to be.
My experience leaves me with a renewed sense of awe for what anaesthetists do as a matter of routine. Without really understanding how, they guide hundreds of millions of people a year as close to the brink of nothingness as it is possible to go without dying. Then they bring them safely back home again.
Linda Geddes is a reporter at New Scientist
Source: NewScientist
http://www.newscientist.com/article/mg21228402.300-banishing-consciousness-the-mystery-of-anaesthesia.html
http://www.newscientist.com/article/mg21228402.300-banishing-consciousness-the-mystery-of-anaesthesia.html
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Robert Karl Stonjek [Thanks Pierre Tremblay]
Robert Karl Stonjek [Thanks Pierre Tremblay]
பென்டிரைவை RAMஆக பயன்படுத்துவதற்கு
 நமது கணணிகளில் சில வேலை போதுமான அளவு RAM காணப்படாமல் இருக்கலாம். மேலதிகமாக RAM ஒன்றை பொறுத்துவதனால் அவற்றின் விலை மிக அதிகமானதாகவே இருக்கின்றன. அதேவேளை பென்டிரைவ்களின் விலை குறைவானதே.முதலில் Windows Xp யில் எவ்வாறு பென்டிரைவ் ஒன்றை RAM ஆக பயன்படுத்தி கணணியின் performanceயை அதிகரிக்கலாம். முதலில் பென்டிரைவ் ஒன்றை(குறைந்தது 1GB) USB port வழியாக பொறுத்துங்கள். 1. பின் My Computer ல் Right Click செய்து Properties தெரிவு செய்யுங்கள். 2. அதிலுள்ள Advanced பகுதியில் Performance இல் உள்ள Settings பொத்தானை அழுத்துங்கள். 3. அதன் பின் தோன்றும் வின்டோவில் Advanced பகுதியில் Change பொத்தானை Click செய்து பென்டிரைவ்வை தெரிவு செய்து கொள்ளுங்கள். 4. பின் Custom Size என்பதை Click செய்து பயன்படுத்த வேண்டிய அளவை டைப் செய்யுங்கள். (Initial மற்றும் Max எனும் இரு பிரிவிலும் ஒரே அளவை வழங்குங்கள்). 5. பின்னர் Set செய்து உங்கள் கணணியை Restart செய்யுங்கள் அல்லது ReadyBoost அல்லது eboostr மென்பொருளை தரவிறக்கம் செய்து கொள்ளுங்கள். பின் பென்டிரைவ்வை பொறுத்தி eboostr control pannel இல் பென்டிரைவ்வை add செய்து பயன்படுத்தலாம். (Restart செய்தல் கட்டாயமானதே) 6. Windows 7 யில் பென்டிரைவ் ஒன்றை RAM ஆக பயன்படுத்தலாம். உங்கள் கணணி 256GB RAM கொண்டிருந்தால் 8 ReadyBoost Devices களை ஒவ்வொன்றும் 32GB கொள்ளவை உடை பென்டிரைவ்களாக பயன்படுத்தலாம். எனவே Windows 7 இல் மொத்தமாக 256GB RAM வரைக்கும் பயன்படுத்தலாம். உங்கள் பென்டிரைவ்வில் Right Click செய்து Properties தெரிவு செய்யுங்கள். அதில் ReadyBoost பகுதியில் Use This Device ஐ தெரிவு செய்யுங்கள். Space to reserve for system speed என்ற இடத்தில் கூட்டி விடவும். இப்போது Apply செய்து விடுங்கள், உங்கள் பென்டிரைவ்வின் Performance உயர்ந்துவிடும். |
மூட்டு வலிக்கான நிரந்தர தீர்வுகள்
 மூட்டு வலி வரக் காரணம் மூட்டு தேய்மானமே. இந்தப் பிரச்சினை இல்லாத இடமே உலகத்தில் இல்லை எனலாம்.மூட்டுத் தேய்மானம் இரண்டு வகைப்படும்: 1. மூட்டழற்சி(osteo arthritis):இது பெரும்பாலும் வயதானவர்களுக்கே வரும் இது பொதுவாக இடுப்பு மூட்டு, கால் மூட்டு, தோள்பட்டை, கழுத்து போன்ற பகுதிகளில் ஏற்படும். 2. முடக்குவாதம்(rheumatoid arthritis): இது எந்த வயதினருக்கும் வரலாம். பெரும்பாலும் விரல்கள், மணிக்கட்டு, கால் போன்ற பகுதிகளையே தாக்கும். அறிகுறிகள்: மூட்டழற்சி: நாள்பட்ட வலி, மூட்டு இறுக்கம், நடந்த பின்போ, வேலை செய்த பின்போ வலி அதிகமாகும். முடக்குவாதம்: இது ஆரம்பத்தில் தெரியாது. நாள்பட்ட வலி மற்றும் பலமூட்டுகளில் வலி போன்றவை ஏற்படும். முழு உடம்பும் பாதிக்கப்பட்டிருக்கும். மேலும் இரத்தசோகை, குடல் அழற்சி, மலச்சிக்கல், தோற்றம் மாறிய கை மற்றும் பாதம் போன்றவை காணப்படும். காரணம்: அதிக பளு தூக்குதலால் மூட்டின் உள் பகுதியில் ஏற்படும் மாற்றம். முடக்குவாதம்: சில கிருமிகளினாலும், ஹார்மோன் எனப்படும் நாளமில்லா சுரப்பிகளின் ஒழுங்கற்ற பணியாலும் ஏற்படுகிறது. மேலும் மன அழுத்தம், சீரற்ற மனநிலை, நோய்த்தொற்று, அடிபடுதல் போன்றவையும் காரணமாகும், பரம்பரை ரீதியாகவும் மூட்டுத்தேய்மானம் ஏற்படலாம். வைத்தியம்: 1. நல்ல நடுத்தரமான உருளைக்கிழங்கு ஒன்றை மெல்லிய வில்லைகளாக வெட்டி ஒரு கோப்பை குளிர்ந்த நீரில் இரவு முழுதும் ஊறவைத்து பின் காலையில் அந்த நீரை வெறும் வயிற்றில் குடிக்க வேண்டும். உருளைகிழங்கு சாறையும் அருந்தலாம். இது மூட்டு வலிக்கு மிகச்சிறந்த மருந்தாகும். 2.ஒரு தேக்கரண்டி கறுப்பு எள்ளை கால் கோப்பை தண்ணீரில் இரவு முழுதும் ஊறவைத்து பிறகு காலையில் வெறும் வயிற்றில் சாப்பிட வேண்டும். 3. இரண்டு தேக்கரண்டி எலுமிச்சை சாற்றை ஒரு தேக்கரண்டி தேனுடன் ஒரு கோப்பை வெதுவெதுப்பான நீரில் பிழிந்து தினம் இருமுறை வெறும் வயிற்றில் சாப்பிடலாம். 4. வெதுவெதுப்பான தேங்காய் அல்லது கடு எண்ணெயில் சிறிது கற்பூரத்தை போட்டு மூட்டில் நன்கு தேய்த்தால் வலி குறையும். இது மூட்டுவலிக்கு உடனடி தீர்வாகும். 5. ஒரு தேக்கரண்டி குதிரைமசால்(இது ஒரு கால் நடை தீவனம்) விதைகளை ஒரு கோப்பை நீரில் கொதிக்க வைத்து தேநீர் போல ஒரு நாளைக்கு மூன்று-நான்கு முறை அருந்தலாம். 6. இரண்டு மேஜைக்கரண்டி விளக்கெண்ணையை அடுப்பில் சூடேற்றி ஒரு கோப்பை ஆரஞ்சு சாற்றில் விட்டு காலையில் உணவிற்கு முன் சாப்பிட வேண்டும். இதை நோய் தீரும் வரை செய்ய வேண்டும்.(இது ஒரு ஸ்பெயின் மருத்துவரின் குறிப்பு, மேலும் நல்ல பலனை தரும்). மூன்று வாரங்கள் தொடர்ந்து செய்ய வேண்டும். பிறகு மூன்று வாரங்கள் விட்டு விட வேண்டும். மீண்டும் மூன்று வாரங்கள் செய்ய வேண்டும். இந்த மருந்தை சாப்பிடும் போது நாம் காரமான உணவு வகைகளை அதிகம் எடுத்துக் கொண்டு புளிப்பான உணவு வகைகளை தவிர்க்க வேண்டும். இல்லையென்றால் மருந்து பலன் தராது. 7. ஒரு மேஜைக்கரண்டி பச்சை அல்லது பாசிப்பருப்பை இரண்டு பூண்டு பற்களுடன் வேகவைத்து சூப்பாக நாளொன்றுக்கு இருமுறை சாப்பிட வேண்டும். உணவுப்பழக்கம்: 1. வாழைப்பழம் அதிகமாக உண்ண வேண்டும். 2. காய்கறி சூப் அதிகமாக சாப்பிட வேண்டும். கேரட், பீட்ரூட் போன்றவற்றை பச்சையாக சாப்பிடலாம். 3. கால்சியம் அதிகம் உள்ள பால்,பால் சார்ந்த பொருட்கள், முள் நிறைந்த மீன் போன்றவற்றை சாப்பிட வேண்டும் தவிர்க்க வேண்டியவை: காரமான வறுத்த உணவுகள், தேநீர், காபி, பகல் தூக்கம், மனக்கவலைகள், மன அழுத்தம். |
மனிதர்களை அழிக்கக்கூடிய மனிதனால் உருவாக்கப்பட்ட வைரஸ்
மனிதர்களையே அழித்துவிடக்கூடிய மனிதனால் உருவாக்கப்பட்ட Flu வைரசினைக் கண்டுபிடித்தமை பற்றிய விபரங்களை நெதர்லாந்தின் விஞ்ஞானிகள் வெளியிடவுள்ளனர். இந்த அபாயகரமான வைரஸ் H5N1 பறவைக்காய்ச்சல் வைரசினை ஒத்ததாகும். ஆனால் இது அதனை விடவும் கிருமித்தொற்று மிக்கதென்றும் ஒரு தடவையிலேயே மில்லியன் கணக்கானோரில் கடத்தப்பட்டுவிடும் என்றும் கூறப்படுகின்றது. இதனால் இந்த ஆய்வு சர்ச்சைக்குரிய நிலையை ஏற்படுத்தியுள்ளதுடன் விஞ்ஞானிகளையும் இரு பிரிவாகப் பிரித்துள்ளது. ஒரு பகுதியினர் இதன் விபரங்களை வெளியிடக்கூடாது என்றும் சிலர இதனைச் செய்யவேண்டும் என்றும் தெரிவித்தனர். பறவைக் காய்ச்சலின் வைரஸ் 500 பேரை மட்டுமே கொன்றது. அத்துடன் உலகளாவிய ரீதியில் பரம்பலடையாது. ஆனால் தற்போது உருவாக்கப்பட்ட வைரஸ் எதிரிகளின் கைகளில் கிடைத்துவிட்டால் மிகவும் ஆபத்தானதாக உள்ளதால் உயிரியல் போரிற்குப் பயன்படுத்தக்கூடிய அபாயத்தை ஏற்படுத்திவிடலாம் என்ற அச்சம் ஏற்பட்டுள்ளது. எனினும் இந்த ஆய்வு சர்வதேசத்தினை H5N1 இனை முமுவதும் விளங்கிக்கொள்வதன் பாகமாகவே மேற்கொள்ளப்பட்டதென இவ்விஞ்ஞானிகள் தெரிவிக்கின்றனர். இந்தக் கண்டுபிடிப்பினால் இக்குழு ஊடகத்தின் பாய்ச்சலினை எதிர்கொள்ளவேண்டிய நிலையிலும் உள்ளது. இந்தக் கண்டுபிடிப்பு மருத்துவரீதியில் நல்லதாரு முன்னேற்றம் எனினும் துணைபோகக்கூடும் என்றும் கருதப்படுகின்றது. இதனால் இதுபற்றிய விடயங்களை வெளியிடுவது தடுக்கப்படவேண்டுமென்றும் வெளியிடப்பட்டால் உயிரியல் தீவிரவாதத்திற்குத் துணைபோகும் காரியங்களைச் செய்பவர்களுக்கு இது உதவக்கூடுமென்றும் ஆய்வாளர்கள் கூறுகின்றனர். |
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