A pesar de ser insufribles ahora parece que haypruebas 2científicas" de que los exámenes son "buenos". Eso si no te matan de ansiedad...
Testing Boosts Memory
By Jennifer Cutraro
Students who break into a cold sweat at the thought of a pop quiz might feel better once they learn about a side effect of test-taking: The practice appears to enhance memory, possibly even more than studying. What's more, according to a new study, testing also helps students remember material that wasn't on the exam in the first place.
Over the past several years, cognitive scientists have documented a phenomenon called the "testing effect," in which taking a test, rather than studying, boosts an individual's ability to remember the material later on. The research led psychology doctoral student Jason Chan and his colleagues at Washington University in St. Louis, Missouri, to wonder whether testing also affects memory for untested materials.
To test the theory, the team had 84 undergraduate students read a passage about toucans, a topic the researchers believed would be unfamiliar to psychology undergraduates. After reading the passage, one-third of the students were dismissed, one-third were asked to read an additional set of study materials that covered the same information as the original passage, and one-third were asked to take a brief short-answer test on the original material. The next day, all participants returned to take a final short-answer test, which included questions from the previous day's brief test as well as new questions.
Nootrópicos (smartdrugs, drogas inteligentes, potenciadores cognitivos) son sustancias artificiales (medicamentos como piracetam, hydergina, citicolina, fosfatidilserina, vinpocetina, etc.) o naturales (suplementos nutricionales, vitaminas, aminoácidos, hormonas, hierbas, etc. como vitaminas B, piroglutamato, Gingko Biloba, fenilalanina, DHEA, pregnenolona, etc.) que se utilizan para mejorar la capacidad cognitiva (memoria, atención, etc.) en personas con trastornos o normales.
martes, noviembre 14, 2006
jueves, noviembre 09, 2006
Efecto del estres cronico sobre la atencion
Chronic stress affects attention by altering neuronal growth in the brain (ver completo)
Anxiety and depression can make a person feel as if he’s battling his own brain, complete with wounds and scars. Traumatic events war, divorce, the death of a loved one can trigger these disorders, and scientists are just beginning to clarify the biological connection. Now, working neuron by neuron, researchers have found that life experiences actually appear to change the length and complexity of individual brain cells. In a recent study published in The Journal of Neuroscience, Rockefeller University scientists show that chronic daily stress affected neurons in two different areas of the rat brain, showing for the first time a link between anxiety symptoms and the dynamic anatomy of the brain.
One of the characteristic manifestations of prolonged stress is decreased performance in tasks that require attention, including the ability to shift focus as well as to learn and unlearn information. Bruce McEwen, Rockefeller’s Alfred E. Mirsky Professor and head of the Harold and Margaret Milliken Hatch Laboratory of Neuroendocrinology, was interested in finding out how this translates to changes in the brain itself. So he and Conor Liston, a graduate student in McEwen’s lab, compared neuronal change in stressed and unstressed rats.
The researchers stressed out a dozen rats by keeping them in painless restraints for six hours a day. Then, after 21 days, they used a complex progression of trials to test how quickly the rats learned to make associations between different cues and the location of hidden food. First, Liston provided two different materials for the rats to dig in, such as sand and sawdust, and buried food consistently under only one. Next, he left the food in the same material but scented it with strong spices (like cumin or nutmeg) that were unrelated to the food’s location.
domingo, noviembre 05, 2006
Rejunte de links sobre Sapolsky
transcript of 's How I Write Conversation.
http://www.stanford.edu/group/howiwrite/Transcripts/Sapolsky_transcript.html
video
http://vodreal.stanford.edu/urp/hiw/040903.ram
datos biograficos
http://www.stanford.edu/group/howiwrite/Bios/robertsapolsky/
Depression in the Brain
http://www.lcmedia.com/mind377.htm
Anxiety (cited)
http://www.mcmanweb.com/anxiety.htm
Weblog post about Sapolsky with links
http://jollysocratic.blogspot.com/2005/10/robert-sapolsky-on-stress.html
Taming Stress
An emerging understanding of the brain's stress pathways points toward
treatments for anxiety and depression beyond Valium and Prozac
By Robert Sapolsky
http://www.sciam.com/print_version.cfm?articleID=00083A00-318C-1F30-9AD380A84189F2D7
'Monkeyluv': Primates Are People, Too
By JAMIE SHREEVE
Published: November 6, 2005
http://www.nytimes.com/2005/11/06/books/review/06shreeve.html
"Why Zebras Don't Get Ulcers"
by David Ruenzel
Dr. Robert Sapolsky is a Professor of Neurology at Stanford University.
Dr.Sapolsky Spoke at the Brain Connection to Education Spring Conference 2000.
http://www.brainconnection.com/topics/printindex.php3?main=fa/zebras
A Conversation With Robert Sapolsky
by Simon Hanson, Ph.D.
http://www.brainconnection.com/topics/printindex.php3?main=conv/sapolsky
Why Zebras Don't Get Ulcers : An Updated Guide To Stress, Stress Related
Diseases, and Coping ("Scientific American" Library) (Paperback)
by Robert M. Sapolsky
http://www.amazon.com/exec/obidos/tg/detail/-/0716732106/104-6068630-1823122?v=glance
También buscar en Google video y YouTube.
viernes, noviembre 03, 2006
DHA, p300 latency and Memory
DHA and Memory
Myanaga, K, Yonemura, K et al. DHA Shortens p300 latency in healthy persons. International Conference on Highly Unsaturated Fatty Acids in Nutrition and Disease Prevention 1996. Barcelona, Spain.
A certain type of brain wave called p300 is linked to memory and learning. The faster the rate of transmission, the more efficiently the brain is functioning. The rate declines with age, and is slower in people with dementia. To demonstrate if Omega-3 fatty acids influence this brain function, researchers took 26 normal adult volunteers hooked them up to electrodes and gave them a test that determined their p300 rate. Immediately after taking the test, they were given supplements of either EPA or DHA (both are derivatives of Omega-3 from fish). Two hours later, their brain waves were measured, and this time the p300 rate was significantly faster in the group given the DHA supplements, supporting their hypothesis that DHA might enhance mental abilities in adults as well.
Myanaga, K, Yonemura, K et al. DHA Shortens p300 latency in healthy persons. International Conference on Highly Unsaturated Fatty Acids in Nutrition and Disease Prevention 1996. Barcelona, Spain.
A certain type of brain wave called p300 is linked to memory and learning. The faster the rate of transmission, the more efficiently the brain is functioning. The rate declines with age, and is slower in people with dementia. To demonstrate if Omega-3 fatty acids influence this brain function, researchers took 26 normal adult volunteers hooked them up to electrodes and gave them a test that determined their p300 rate. Immediately after taking the test, they were given supplements of either EPA or DHA (both are derivatives of Omega-3 from fish). Two hours later, their brain waves were measured, and this time the p300 rate was significantly faster in the group given the DHA supplements, supporting their hypothesis that DHA might enhance mental abilities in adults as well.
martes, octubre 24, 2006
No todo es malo con la edad para el cerebro
STUDY SHOWS YOUR BRAIN GETS BETTER WITH AGE!
Brain-imaging is revealing many things about our brains that challenge the way we’ve traditionally thought about brain function and development. Here’s a report on a brain-imaging based study released this month …
It turns out the brain is more like fine wine than cheap beer: It gets better and more sophisticated with age, according to a new University of New Mexico study. The body stops producing gray matter – the stuff the brain's thinking lobes are made out of – at about age 16.
But white matter – the connective fiber between the lobes that allows parts of the brain to interact with each other – continues to grow until about age 45, according to the study by UNM's Health Sciences Center and New Mexico VA Health Care Systems.
“It looks like in some ways people between ages 35 to 45 are actually at their prime in terms of brain development,” said Cheryl Aine, a UNM researcher and lead author of a paper that details the findings in the Oct. 1 issue of the journal NeuroImage.
Scientists used to think it was all downhill for the brain after the teenage years, because gray matter stops developing and shrinks as people enter their 20s, Aine said. In the study, scientists scrutinized that theory by imaging the brains of people in three age groups – people 20-29, 35-45 and those older than 60.
They found that gray matter becomes more refined, and the white matter “superhighway” that sends information between them keeps growing well into adulthood. “We lose some of the gray matter because we get rid of the extra synapses we don't use,” Aine said. “It's more sculpted after that. It's more efficient.”
When it comes to memory and learning, young brains do still have an edge, said Janice Knoefel, a physician in geriatrics at the VA Hospital who also worked on the study. “Attention tends to decline and memory tends to decline as we get older,” she said. “But we use different strategies to remember things.”
by Sue Vorenberg
from the Scripps Howard News Service
Another thing we’re learning is just how much it matters that we care for our brains. Proper nutrition, rest, physical and mental exercise are essential to keeping our brains in prime condition as we age. Our internal research here at Amen Clinics is bearing that out. The function (or lack thereof) of certain brain areas has an impact on our behavior, life and family.
The good news is, the better we can identify the parts of the brain that are either working too hard or not hard enough, the better we can focus our treatment on that area. So, there’s hope for all of us on “the back side of forty”. Our brains really can improve with age and the proper care. And, as we understand the brain better, I believe our best brain-health days are yet to come!
To Your Brain Health,
Daniel
Daniel Amen, M.D.
www.amenclinics.com
Brain-imaging is revealing many things about our brains that challenge the way we’ve traditionally thought about brain function and development. Here’s a report on a brain-imaging based study released this month …
It turns out the brain is more like fine wine than cheap beer: It gets better and more sophisticated with age, according to a new University of New Mexico study. The body stops producing gray matter – the stuff the brain's thinking lobes are made out of – at about age 16.
But white matter – the connective fiber between the lobes that allows parts of the brain to interact with each other – continues to grow until about age 45, according to the study by UNM's Health Sciences Center and New Mexico VA Health Care Systems.
“It looks like in some ways people between ages 35 to 45 are actually at their prime in terms of brain development,” said Cheryl Aine, a UNM researcher and lead author of a paper that details the findings in the Oct. 1 issue of the journal NeuroImage.
Scientists used to think it was all downhill for the brain after the teenage years, because gray matter stops developing and shrinks as people enter their 20s, Aine said. In the study, scientists scrutinized that theory by imaging the brains of people in three age groups – people 20-29, 35-45 and those older than 60.
They found that gray matter becomes more refined, and the white matter “superhighway” that sends information between them keeps growing well into adulthood. “We lose some of the gray matter because we get rid of the extra synapses we don't use,” Aine said. “It's more sculpted after that. It's more efficient.”
When it comes to memory and learning, young brains do still have an edge, said Janice Knoefel, a physician in geriatrics at the VA Hospital who also worked on the study. “Attention tends to decline and memory tends to decline as we get older,” she said. “But we use different strategies to remember things.”
by Sue Vorenberg
from the Scripps Howard News Service
Another thing we’re learning is just how much it matters that we care for our brains. Proper nutrition, rest, physical and mental exercise are essential to keeping our brains in prime condition as we age. Our internal research here at Amen Clinics is bearing that out. The function (or lack thereof) of certain brain areas has an impact on our behavior, life and family.
The good news is, the better we can identify the parts of the brain that are either working too hard or not hard enough, the better we can focus our treatment on that area. So, there’s hope for all of us on “the back side of forty”. Our brains really can improve with age and the proper care. And, as we understand the brain better, I believe our best brain-health days are yet to come!
To Your Brain Health,
Daniel
Daniel Amen, M.D.
www.amenclinics.com
Las frutillas son buenas para la memoria
Fisetin, a naturally occurring flavonoid commonly found in strawberries and other fruits and vegetables, stimulates signaling pathways that enhance long-term memory, report researchers at the Salk Institute for Biological Studies.
...
Besides strawberries, fisetin is found in tomatoes, onions, oranges, apples, peaches, grapes, kiwifruit and persimmons. Gingko biloba leaves, while rich in other flavonoids, do not contain fisetin.
While eating strawberries sounds like an enjoyable alternative to popping a pill, Maher cautions that it would take about 10 pounds a day to achieve a beneficial effect, which might prove too much even for the most avid strawberry lovers.
sciencedaily
...
Besides strawberries, fisetin is found in tomatoes, onions, oranges, apples, peaches, grapes, kiwifruit and persimmons. Gingko biloba leaves, while rich in other flavonoids, do not contain fisetin.
While eating strawberries sounds like an enjoyable alternative to popping a pill, Maher cautions that it would take about 10 pounds a day to achieve a beneficial effect, which might prove too much even for the most avid strawberry lovers.
sciencedaily
sábado, octubre 07, 2006
Alga Wakame
Parece que al alga Wakame (Undaria pinnatifida) le están encontrando muy buenas propiedades para prevenir enfermedades. El Wakame contiene un carotenoide llamado fucoxantina (fucoxanthin en Inglés) que no está presente en otras algas como el Nori y reduce los daños en modelos animales de infartos cerebrales, inhibe el cáncer, la hipertensión e incluso disminuye la obesidad.
Algunos especulan que el consumo de Wakame podría ser el factor responsable de la longevidad de las mujeres asiáticas de Bergen County, USA quienes tienen una expectativa de vida de 90 años.
Demasiado bueno para creerlo, pero se pueden encontrar los artículos en pubmed.com
¿Tendrá el gusto inmundo de las otras algas?.
Algunos especulan que el consumo de Wakame podría ser el factor responsable de la longevidad de las mujeres asiáticas de Bergen County, USA quienes tienen una expectativa de vida de 90 años.
Demasiado bueno para creerlo, pero se pueden encontrar los artículos en pubmed.com
¿Tendrá el gusto inmundo de las otras algas?.
miércoles, septiembre 27, 2006
Fanatica del Ginkgo
Name: Cor Kwant
About Me: Teacher, creator and webmaster of The Ginkgo Pages, a non-commercial awarded homepage about all aspects of the Ginkgo biloba tree, translated into German, French, Spanish and Dutch.
Su blog es: The Ginkgo Pages Forum - Blog
Incluye un interesante post en el que detalla las marcas de ginkgo que pasaron los tests de Consumerlab.
About Me: Teacher, creator and webmaster of The Ginkgo Pages, a non-commercial awarded homepage about all aspects of the Ginkgo biloba tree, translated into German, French, Spanish and Dutch.
Su blog es: The Ginkgo Pages Forum - Blog
Incluye un interesante post en el que detalla las marcas de ginkgo que pasaron los tests de Consumerlab.
Atlas del cerebro
"We have essentially mapped each individual gene in the mouse brain, about 21,000 genes in all, down to the cellular level," said Allan Jones, chief scientific officer at the Allen Institute for Brain Science.
www.brainatlas.org
www.brainatlas.org
lunes, septiembre 11, 2006
quinasa M zeta proteina que refuerza la memoria
Noticia interesante a pesar de los errores de ortografía.
"El trabajo se publicó el pasado 25 de agosto en Science y en él se describe la encima llamada quinasa M zeta. Esta proteína conserva la memoria a largo plazo a través un refuerzo persistente de las conexiones sinápticas entre las neuronas. Inhibiendo la enzima los científicos fueron capaces de borrar los recuerdos almacenados en un día o incluso en un mes. Esta función en el almacenamiento de la memoria es específica de esta proteína porque inhibiendo otras moléculas similares no se obtienen los mismos resultados."
novaciencia
"El trabajo se publicó el pasado 25 de agosto en Science y en él se describe la encima llamada quinasa M zeta. Esta proteína conserva la memoria a largo plazo a través un refuerzo persistente de las conexiones sinápticas entre las neuronas. Inhibiendo la enzima los científicos fueron capaces de borrar los recuerdos almacenados en un día o incluso en un mes. Esta función en el almacenamiento de la memoria es específica de esta proteína porque inhibiendo otras moléculas similares no se obtienen los mismos resultados."
novaciencia
martes, septiembre 05, 2006
Nutricion y salud mental
Un artículo sobresimplificador y remanido (además de peligrosamente antifármacos) pero del que se puede sacar alguna recomendación.
Four brain chemicals -- serotonin, catecholamine, GABA and endorphin -- are essential for proper mental health, each affecting a different area of the brain. Some of us, unfortunately, have a genetic predisposition to lack these chemicals. Additionally, the modern mainstream diet is deficient in the amino acids that our brains need to make these neurotransmitters. As a result of these factors, incidence of depression and anxiety has reached epidemic proportions.
Achieve optimum mental health by supplementing deficient brain chemicals instead of resorting to dangerous antidepressant drugs
Four brain chemicals -- serotonin, catecholamine, GABA and endorphin -- are essential for proper mental health, each affecting a different area of the brain. Some of us, unfortunately, have a genetic predisposition to lack these chemicals. Additionally, the modern mainstream diet is deficient in the amino acids that our brains need to make these neurotransmitters. As a result of these factors, incidence of depression and anxiety has reached epidemic proportions.
Achieve optimum mental health by supplementing deficient brain chemicals instead of resorting to dangerous antidepressant drugs
domingo, septiembre 03, 2006
Idebenona si o no?
Hay opiniones encontradas sobre la conveniencia de usar idebenona (un análogo sintético de la Coenzima Q10 cuya acción se da principalmente a nivel de las mitocondrias). Algunos la acusan de ser pro-oxidante (superóxido).
Idebenona sí o idebenona no?
Idebenona sí o idebenona no?
viernes, septiembre 01, 2006
l-carnitina o acetil-l-carnitina?
A pesar de que muchos afirman que la acetil l-carnitina (ALCAR) es superior a la l-carnitina (especialmente para las mitocondrias y el cerebro), este artículo explica cómo una se transforma en la otra. Habrá que tener en cuenta también a los que usan ALCAR como juvenon.com . La carnitina es mucho más barata que la ALCAR por lo que no estaría mal empezar por la primera.
2. What form is best?
Pharmacologically speaking, there is little difference between supplementing with L-carnitine and supplementing with ALCAR. This is because ALCAR is deacetylated during or immediately after intestinal cell uptake, and then a certain amount of free carnitine is later reacetylated (1, 2). Similarly, it has been shown that supplementation with both L-carnitine and ALCAR increase tissue levels of both substances, and that the intestine creates significant amounts of ALCAR from carnitine (2, 3).
7. How should carnitine be taken?
The typical dosage for carnitine is 1-4 g/day (65). A study on the pharmacokinetics of oral L-carnitine in human subjects found no differences in plasma carnitine after 2 g vs. 6 g, indicating that 2 g is already more than the saturable dose (66). The half-life of the 2 gram dose was 6.5 hours, and this would imply that the ideal dosing schedule would be 1-2 grams 2-3 times daily, although many studies indicate beneficial effects with only .5-1.5 grams daily.
1. Iossa S, Mollica MP, Lionetti L, Crescenzo R, Botta M, Barletta A, Liverini G. Acetyl-L-carnitine supplementation differently influences nutrient partitioning, serum leptin concentration and skeletal muscle mitochondrial respiration in young and old rats. J Nutr 2002 Apr;132(4):636-42
2. Gross CJ, Henderson LM, Savaiano DA. Uptake of L-carnitine, D-carnitine and acetyl-L-carnitine by isolated guinea-pig enterocytes. Biochim Biophys Acta 1986 May 29;886(3):425-33 [abstract]
3. Gudjonsson H, Li BU, Shug AL, Olsen WA. In vivo studies of intestinal carnitine absorption in rats. Gastroenterology 1985 Jun;88(6):1880-7
L-Carnitine Description By David Tolson
2. What form is best?
Pharmacologically speaking, there is little difference between supplementing with L-carnitine and supplementing with ALCAR. This is because ALCAR is deacetylated during or immediately after intestinal cell uptake, and then a certain amount of free carnitine is later reacetylated (1, 2). Similarly, it has been shown that supplementation with both L-carnitine and ALCAR increase tissue levels of both substances, and that the intestine creates significant amounts of ALCAR from carnitine (2, 3).
7. How should carnitine be taken?
The typical dosage for carnitine is 1-4 g/day (65). A study on the pharmacokinetics of oral L-carnitine in human subjects found no differences in plasma carnitine after 2 g vs. 6 g, indicating that 2 g is already more than the saturable dose (66). The half-life of the 2 gram dose was 6.5 hours, and this would imply that the ideal dosing schedule would be 1-2 grams 2-3 times daily, although many studies indicate beneficial effects with only .5-1.5 grams daily.
1. Iossa S, Mollica MP, Lionetti L, Crescenzo R, Botta M, Barletta A, Liverini G. Acetyl-L-carnitine supplementation differently influences nutrient partitioning, serum leptin concentration and skeletal muscle mitochondrial respiration in young and old rats. J Nutr 2002 Apr;132(4):636-42
2. Gross CJ, Henderson LM, Savaiano DA. Uptake of L-carnitine, D-carnitine and acetyl-L-carnitine by isolated guinea-pig enterocytes. Biochim Biophys Acta 1986 May 29;886(3):425-33 [abstract]
3. Gudjonsson H, Li BU, Shug AL, Olsen WA. In vivo studies of intestinal carnitine absorption in rats. Gastroenterology 1985 Jun;88(6):1880-7
L-Carnitine Description By David Tolson
lunes, agosto 28, 2006
Videos estres y cerebro
Estrés y placer, extremos encontrados
Clip de la entrevista de Eduard Punset con el biólogo Robert Sapolsky. Más
información en texto en smartplanet.
video en youtube
'Stress, Neurodegeneration and Individual Differences' by Robert Sapolsky
video en Google
domingo, agosto 27, 2006
Articulo en Quo
Un artículo con varias cosas criticables, pero como para lerlo:
Recarga tu mente
¿Hasta dónde llegarías para sacar el máximo partido a tu cerebro?
El doping intelectual es ya una tentación a tu alcance.
Fuente: quo.wanadoo.es
Recarga tu mente
¿Hasta dónde llegarías para sacar el máximo partido a tu cerebro?
El doping intelectual es ya una tentación a tu alcance.
Fuente: quo.wanadoo.es
viernes, agosto 25, 2006
Fechas de vencimiento de los suplementos y drogas
Q Is there any problem in taking vitamins a year or so past the expiration date? Are there specific vitamins that would deteriorate so much that one shouldn’t take them?
A This is a commonly asked question, and the answer must be qualified. Regarding drugs, the FDA has monitored what they call the shelf life extension program (SLEP) of drugs for the past 20 years for the United States Department of Defense.1 Extensive pharmaceutical stability data indicate that in 88% of the drugs tested (122 in all, representing 3005 different lots), shelf life was extended for at least one year beyond the originally indicated expiration date—and by an average of 66 months! However, there was a lot of variability during the extended period, and the FDA reported that the only way to be assured of continuing potency was through periodic testing and systematic evaluation of each lot.
Regarding supplements such as vitamins, minerals, amino acids, and other nutrients, no large study has ever been undertaken, as far as I know. (With all that testing, the cost of the SLEP study must have been staggering!) But we do know, from stress and stability studies of individual supplements, that there is a great deal of variability, just as there was in the SLEP study.
The principal factor that determines shelf life is initial quality. The supplement must have essential material as much as is reasonably possible and, by the same token, low levels of nonessential material. It must also have low levels of prooxidative residues, as little moisture as possible, and, if synthesized (as most vitamins are), great chemical stability. Herbal materials must have nearly unmeasurable levels of bacteria or be sterilized. The supplement must be packaged in opaque and secure containers in a clean or sterile, dust-free, air-conditioned, dehumidified environment and not be subjected to extremes in temperature. Finally, as you have undoubtedly seen on the labels, the supplements should be stored in a cool, dark, dry place.
Products made under the above conditions, if stored properly in unopened bottles, should last at least two years before any loss of potency occurs, and, once opened, they should hold up for at least one year.
Initial quality is paramount. For example, the vitamin C developed by Hoffmann-La Roche has been found to outlast other vitamin C products by many years (unopened samples have maintained their purity and potency for up to 20 years). Other vitamin C products have been found to darken, changing color from brown to gray to black in only a few years. This darkening reflects the formation of dehydroascorbic acid, an oxidized form of vitamin C that is undesirable to ingest. Life Enhancement Products uses only vitamins manufactured by the successor company to Hoffmann-La Roche, as well as amino acids, hormones, herbs, and other supplements from the world’s premium producers.
Lyon RC, Taylor JS, Porter DA, Prasanna HR, Hussain AS. Stability profiles of drug products extended beyond labeled expiration dates. J Pharm Sci 2006 Jul;95(7):1549-60.
Supplement Expiration Dates: How Reliable Are They?
A This is a commonly asked question, and the answer must be qualified. Regarding drugs, the FDA has monitored what they call the shelf life extension program (SLEP) of drugs for the past 20 years for the United States Department of Defense.1 Extensive pharmaceutical stability data indicate that in 88% of the drugs tested (122 in all, representing 3005 different lots), shelf life was extended for at least one year beyond the originally indicated expiration date—and by an average of 66 months! However, there was a lot of variability during the extended period, and the FDA reported that the only way to be assured of continuing potency was through periodic testing and systematic evaluation of each lot.
Regarding supplements such as vitamins, minerals, amino acids, and other nutrients, no large study has ever been undertaken, as far as I know. (With all that testing, the cost of the SLEP study must have been staggering!) But we do know, from stress and stability studies of individual supplements, that there is a great deal of variability, just as there was in the SLEP study.
The principal factor that determines shelf life is initial quality. The supplement must have essential material as much as is reasonably possible and, by the same token, low levels of nonessential material. It must also have low levels of prooxidative residues, as little moisture as possible, and, if synthesized (as most vitamins are), great chemical stability. Herbal materials must have nearly unmeasurable levels of bacteria or be sterilized. The supplement must be packaged in opaque and secure containers in a clean or sterile, dust-free, air-conditioned, dehumidified environment and not be subjected to extremes in temperature. Finally, as you have undoubtedly seen on the labels, the supplements should be stored in a cool, dark, dry place.
Products made under the above conditions, if stored properly in unopened bottles, should last at least two years before any loss of potency occurs, and, once opened, they should hold up for at least one year.
Initial quality is paramount. For example, the vitamin C developed by Hoffmann-La Roche has been found to outlast other vitamin C products by many years (unopened samples have maintained their purity and potency for up to 20 years). Other vitamin C products have been found to darken, changing color from brown to gray to black in only a few years. This darkening reflects the formation of dehydroascorbic acid, an oxidized form of vitamin C that is undesirable to ingest. Life Enhancement Products uses only vitamins manufactured by the successor company to Hoffmann-La Roche, as well as amino acids, hormones, herbs, and other supplements from the world’s premium producers.
Lyon RC, Taylor JS, Porter DA, Prasanna HR, Hussain AS. Stability profiles of drug products extended beyond labeled expiration dates. J Pharm Sci 2006 Jul;95(7):1549-60.
Supplement Expiration Dates: How Reliable Are They?
jueves, agosto 17, 2006
BBC - Radio 4 Memory Experience - Improve your memory
BBC - Radio 4 Memory Experience - Improve your memory: "Tips and techniques to improve your memory
Memory Strategies - do what the experts do!
Memory isn't like a muscle, something specific you can exercise. It's a way of organising information in your brain. So to improve your memory, you need to change and re-organise the way you think and this will help to support how your memory works."
Memory Strategies - do what the experts do!
Memory isn't like a muscle, something specific you can exercise. It's a way of organising information in your brain. So to improve your memory, you need to change and re-organise the way you think and this will help to support how your memory works."
martes, agosto 08, 2006
Curcuma para el Alzheimer
En hipocampo.org hay una nota en Español que pongo abajo sobre lo que mencioné antes de la curcumina y el Alzheimer:
El pigmento del curry, nueva esperanza para el Alzheimer
La curcumina (Curcuma longa, azafrán de Las Indias), pigmento amarillo utilizado en la elaboración del polvo de curry, podría constituir una nueva esperanza en el tratamiento de la enfermedad de Alzheimer. La revista Journal of Biological Chemistry publica en su edición preliminar online un estudio de investigadores de la Universidad de California en Los Ángeles que muestra cómo la curcumina inhibe in vivo la formación de ß-amiloide (ßA).
La curcumina ya ha demostrado con anterioridad fuertes propiedades antiinflamatorias y antioxidantes, siendo capaz de suprimir el daño oxidativo, la inflamación, los déficit cognoscitivos y la acumulación de amiloide.
Dado que la estructura molecular de la curcumina sugería su potencial de ligarse al ßA, los autores de este estudio decidieron investigar si su eficacia en modelos de enfermedad de Alzheimer podría explicarse mediante sus efectos sobre la agregación del ßA.
Bajo condiciones de agregación in vitro, la curcumina no sólo inhibe la agregación, sino que también muestra poder de desagregación del ßA(40) fibrilar, indicando una estequiometría favorable para la inhibición. Demostró ser mejor inhibidor de la agregación del ßA(40) que el ibuprofeno y el naproxeno, e impidió la formación y toxicidad del oligómero ßA(42). Estos efectos de la curcumina no dependían de la secuencia del ßA, sino de su conformación fibrilar. Unos cortes cerebrales incubados con curcumina, procedentes de ratones transgénicos modelo de enfermedad de Alzheimer, revelaron un marcado preferencial de la placas de amiloide.
Los estudios in vivo demostraron que la injección de curcumina por vía periférica atravesaba la barrera hematoencefálica y se ligaba a las placas de amiloide en ratones transgénicos de avanzada edad. Usada como alimento en viejos ratones transgénicos Tg2576 (un modelo transgénico de enfermedad de Alzheimer) con avanzada acumulación de amiloide, la curcumina marcaba las placas y reducía tanto los niveles de amiloide como la carga de placas.
Por lo tanto, la curcumina se liga al ßA bloqueando su agregación y su conformación fibrilar, tanto in vitro como in vivo.
Los autores afirman en sus conclusiones que ". . . Estos datos sugieren que la curcumina a dosis bajas desagrega eficazmente el ßA evitando también la formación de fibrillas y oligómeros, respaldando la argumentación para el uso de la curcumina en ensayos clínicos de prevención o tratamiento de la enfermedad de Alzheimer".
F. Yang et al. Curcumin inhibits formation of Aß oligomers and fibrils and binds plaques
and reduces amyloid in vivo. J Biol Chem 2004, 10.1074/jbc.M404751200
hipocampo.org
El pigmento del curry, nueva esperanza para el Alzheimer
La curcumina (Curcuma longa, azafrán de Las Indias), pigmento amarillo utilizado en la elaboración del polvo de curry, podría constituir una nueva esperanza en el tratamiento de la enfermedad de Alzheimer. La revista Journal of Biological Chemistry publica en su edición preliminar online un estudio de investigadores de la Universidad de California en Los Ángeles que muestra cómo la curcumina inhibe in vivo la formación de ß-amiloide (ßA).
La curcumina ya ha demostrado con anterioridad fuertes propiedades antiinflamatorias y antioxidantes, siendo capaz de suprimir el daño oxidativo, la inflamación, los déficit cognoscitivos y la acumulación de amiloide.
Dado que la estructura molecular de la curcumina sugería su potencial de ligarse al ßA, los autores de este estudio decidieron investigar si su eficacia en modelos de enfermedad de Alzheimer podría explicarse mediante sus efectos sobre la agregación del ßA.
Bajo condiciones de agregación in vitro, la curcumina no sólo inhibe la agregación, sino que también muestra poder de desagregación del ßA(40) fibrilar, indicando una estequiometría favorable para la inhibición. Demostró ser mejor inhibidor de la agregación del ßA(40) que el ibuprofeno y el naproxeno, e impidió la formación y toxicidad del oligómero ßA(42). Estos efectos de la curcumina no dependían de la secuencia del ßA, sino de su conformación fibrilar. Unos cortes cerebrales incubados con curcumina, procedentes de ratones transgénicos modelo de enfermedad de Alzheimer, revelaron un marcado preferencial de la placas de amiloide.
Los estudios in vivo demostraron que la injección de curcumina por vía periférica atravesaba la barrera hematoencefálica y se ligaba a las placas de amiloide en ratones transgénicos de avanzada edad. Usada como alimento en viejos ratones transgénicos Tg2576 (un modelo transgénico de enfermedad de Alzheimer) con avanzada acumulación de amiloide, la curcumina marcaba las placas y reducía tanto los niveles de amiloide como la carga de placas.
Por lo tanto, la curcumina se liga al ßA bloqueando su agregación y su conformación fibrilar, tanto in vitro como in vivo.
Los autores afirman en sus conclusiones que ". . . Estos datos sugieren que la curcumina a dosis bajas desagrega eficazmente el ßA evitando también la formación de fibrillas y oligómeros, respaldando la argumentación para el uso de la curcumina en ensayos clínicos de prevención o tratamiento de la enfermedad de Alzheimer".
F. Yang et al. Curcumin inhibits formation of Aß oligomers and fibrils and binds plaques
and reduces amyloid in vivo. J Biol Chem 2004, 10.1074/jbc.M404751200
hipocampo.org
La curcuma mejora el cerebro en ancianos
Popular curry spice is a brain booster
04 August 2006
From New Scientist Print Edition. Subscribe and get 4 free issues.
Call it yellow ginger, haldi, turmeric or E100, the yellow root of Curcuma longa, a staple ingredient in curry, is turning out to be gratifyingly healthy. Now Tze-Pin Ng and colleagues at the National University of Singapore have discovered that curry eating seems to boost brain power in elderly people.
Curcumin, a constituent of turmeric, is an antioxidant, and reports have suggested that it inhibits the build-up of amyloid plaques in people with Alzheimer's. Ng's team looked at the curry-eating habits of 1010 Asian people unaffected by Alzheimer's and aged between 60 and 93, and compared their performance in a standard test of cognitive function, the Mini Mental State Examination. Those people who consumed curry "occasionally" (once or more in 6 months but less than once a month) and "often" (more than once a month) had better MMSE results than those who only ate curry "never or rarely" (American Journal of Epidemiology, DOI: 10.1093/aje/kwj267).
"What is remarkable is that apparently one needs only to consume curry once in a while for the better cognitive performance to be evidenced," says Ng, who says he wants to confirm the results, possibly in a controlled clinical trial comparing curcumin and a placebo.
From issue 2563 of New Scientist magazine, 04 August 2006, page 18
04 August 2006
From New Scientist Print Edition. Subscribe and get 4 free issues.
Call it yellow ginger, haldi, turmeric or E100, the yellow root of Curcuma longa, a staple ingredient in curry, is turning out to be gratifyingly healthy. Now Tze-Pin Ng and colleagues at the National University of Singapore have discovered that curry eating seems to boost brain power in elderly people.
Curcumin, a constituent of turmeric, is an antioxidant, and reports have suggested that it inhibits the build-up of amyloid plaques in people with Alzheimer's. Ng's team looked at the curry-eating habits of 1010 Asian people unaffected by Alzheimer's and aged between 60 and 93, and compared their performance in a standard test of cognitive function, the Mini Mental State Examination. Those people who consumed curry "occasionally" (once or more in 6 months but less than once a month) and "often" (more than once a month) had better MMSE results than those who only ate curry "never or rarely" (American Journal of Epidemiology, DOI: 10.1093/aje/kwj267).
"What is remarkable is that apparently one needs only to consume curry once in a while for the better cognitive performance to be evidenced," says Ng, who says he wants to confirm the results, possibly in a controlled clinical trial comparing curcumin and a placebo.
From issue 2563 of New Scientist magazine, 04 August 2006, page 18
lunes, agosto 07, 2006
Caidas en ancianos pueden indicar problemas cerebrales
Hay una interesante nota en que explica que ciertas lesiones cerebrales como hemorragias producidas por golpes (aún golpes leves o movimientos bruscos de la cabeza en un cerebro que ya está afectado por el encojimiento, lo que produce tensión en los vasos sanguíneos que pueden sangrar), pueden ser la causa de caídas o cambios del comportamiento. Se requiere atención para evitar el paso de tiempo sin atender el problema de base.
As the years go by, the adult brain slowly atrophies, like a desiccated orange detaching from its rind. The shrinkage can cause problems. Cerebral veins are tethered to the superior sagittal sinus, the large blood vessel that runs front to back along the underside of the skull. As the brain contracts, these bridging veins must stretch, making them vulnerable to shearing forces caused by rapid head movements or even modest contusions. Without sufficient brain tissue to support and compress the bleeding site, small, low-pressure venous leaks may go unstanched. The blood seeps into the gap between the arachnoid membrane that encloses the brain and the lining of the skull, or dura mater. Bleeding into this space is called a subdural hematoma.
Acute subdural hematomas result from severe head trauma and expand quickly. Chronic subdural hematomas, on the other hand, often spread slowly—and without visible symptoms. What really scares emergency physicians—and has me repeating to patients and their families, "Return if there's any change in behavior"—is that older people who have fallen can look fine for weeks before the bleeding causes symptoms. By then, relatives will have forgotten the long-ago head knock, attributing Granddad's confusion to the heat, the cold, or a dizzy spell. Without that critical, sometimes lifesaving clue, precious time is lost.
Vital Signs: Why is Grandpa Falling?
A seemingly simple stumble provides clues to serious injury.
By Tony Dajer
DISCOVER Vol. 27 No. 08 | August 2006 |
As the years go by, the adult brain slowly atrophies, like a desiccated orange detaching from its rind. The shrinkage can cause problems. Cerebral veins are tethered to the superior sagittal sinus, the large blood vessel that runs front to back along the underside of the skull. As the brain contracts, these bridging veins must stretch, making them vulnerable to shearing forces caused by rapid head movements or even modest contusions. Without sufficient brain tissue to support and compress the bleeding site, small, low-pressure venous leaks may go unstanched. The blood seeps into the gap between the arachnoid membrane that encloses the brain and the lining of the skull, or dura mater. Bleeding into this space is called a subdural hematoma.
Acute subdural hematomas result from severe head trauma and expand quickly. Chronic subdural hematomas, on the other hand, often spread slowly—and without visible symptoms. What really scares emergency physicians—and has me repeating to patients and their families, "Return if there's any change in behavior"—is that older people who have fallen can look fine for weeks before the bleeding causes symptoms. By then, relatives will have forgotten the long-ago head knock, attributing Granddad's confusion to the heat, the cold, or a dizzy spell. Without that critical, sometimes lifesaving clue, precious time is lost.
Vital Signs: Why is Grandpa Falling?
A seemingly simple stumble provides clues to serious injury.
By Tony Dajer
DISCOVER Vol. 27 No. 08 | August 2006 |
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