aging

Secrets to longevity

dr. dolittle — Mon, 27 Mar 2017 14:40:40 +0000

Secrets to longevity

A new article published in Physiological Reviews compared some remarkable similarities and differences between naked mole rats and humans. Both are relatively long-lived, highly social and have low natural selection pressures. But, this is about all they have in common. While humans are prone to developing age-related cancer, diabetes, heart disease and dementias, naked mole rats are rather resistant to these diseases. Instead, naked mole rats appear to maintain a youthful state throughout their long lives of 30+ years, compared to a mere 3 years for a mouse. To top it off, they do not develop age-related wrinkles and they can continue to procreate throughout their lifespan.

Naked mole rats are not without complications associated with aging as they can show signs of muscle wasting and reduced fat under the skin. The underground life and highly social nature of these animals offers them the protection of a large number of subordinates, which reduces mortality rates and natural selection pressures.

Young (left) and 30-year old (right) naked mole rats. Image from Skulachev et al., 2017.

For many mammals oxidative stress increases with age and further promotes aging by damaging cells. As naked mole rats are resistant to oxidative stress, antioxidants are thought to help slow down aging.

The authors argue that humans have likewise maintained prolonged youth compared to the great apes. To maintain this youth, other structures and functions have been delayed or underdeveloped. For example, like naked mole rats, humans have sacrificed hair, large body size and the muscle strength found in the great apes. Age-related mortality rates are also low for young humans. In contrast, signs of age-related mortality are evident earlier in the development of chimpanzees. Moreover, the human brain (like a naked mole rat) exhibits delayed expression of certain genes and has prolonged growth allowing for complex problem solving.

Source:

, S Holtze, , LE Bakeeva, , , , Neoteny, Prolongation of Youth: From Naked Mole Rats to “Naked Apes” (Humans). Physiological Reviews. 97(2): 699-720, 2017. DOI: 10.1152/physrev.00040.2015

dr. dolittle Mon, 03/27/2017 - 10:40

Tags

Life Science

aging

disease

longevity

naked mole rat

oxidative stress

A huge aspect missing from this news item is that the longevity of the NM rat seems to have been achieved at the cost of sex. Only the queen and a few of her male cohorts get to have sex, everyone else is left without. This will not be acceptable to most humans!

I love naked mole rats.

I love gnarly rodents!!!!

I didnot understand all Of the content ，but still learn a lot things about physicology.

Hey Joanna, if you're trying to understand longevity, aging, and the science behind it, we have a few articles on that written by our scientists at http://longlonglife.org

All good

Aging in men: An evolutionary perspective

gregladen — Mon, 24 Oct 2016 09:05:52 +0000

Aging in men: An evolutionary perspective

Many years ago, Mel Konner, Marjorie shostak, and Boyd Eaton wrote "The Paleolithic Prescription: A program of diet and exercise and a design for living." (It is hard to find these days. To find it and related titles on Amazon, look for this book first, and track the PP down via the author name Konner.)

(Added: You can probably get the The Paleolithic Prescription here.)

Richard G. Bribiescas is professor of anthropology and ecology and evolutionary biology at Yale University, where he also serves as deputy provost for faculty development and diversity. He is the author of Men: Evolutionary and Life History. He lives in Hamden, Connecticut.

That was the first "stone age" diet book. But, it was different from all the others, and the only one worth anything. Mel and Marjorie were two of several individuals, including my advisor and theses readers, Irv Devore and John Yellen, who engaged in the famous Kalahari Project, in which the biology and lifeways of the Ju/'hoansi foragers (aka Bushmen or San) were studied intensively for several years.

The researchers noticed that there were differences in lifeways between these exemplary foragers and industrialized people's of the West that seemed related to health and well being. They were able to link, sometimes definitively, sometimes tentatively, diet and activity levels on one hand and health on the other. Their findings, by the way, were first published in the peer reviewed literature, then turned, by the scientist themselves, into a popular book. (One of the findings eventually led to the understanding that there are different kids of cholesterol, which seem to have very different health related implications.)

My own research with the Efe (Pygmies) of the Ituri Forest, in Zaire, was an indirect offshoot of that early work. I got my PhD at the same institution, Harvard's Anthropology Department that housed much of the Kalahari project, and the Ituri project was started by the same leader, Irv DeVore, via his students. So, the tradition of examining the lifeways of modern day foragers, in part to understand ideal human conditions, and comparing those conditions to western ways continued.

Meanwhile, one of the graduate students at Harvard, Peter Ellison (yes, he is related to that Ellison) had been interested in some work coming out of Harvard Medical school looking at hormones and behavior, especially as related to reproductive biology of human women. Building on that work, Ellison created an entirely new field of study, called "Reproductive Ecology." He finished his PhD and was added to the faculty at the Anthropology department in one of those in between positions (as was I and many others over the years) but Peter became one of the very few such individuals to be eventually offered a tenured position with the most "always hire from outside" institutions ever. And Ellison created the Reproductive Ecology Lab within the biological anthropology wing of Harvard's Department of Anthropology.

And, they studies the heck out of female reproductive ecology. I had the pleasure of working, almost every semester that I was there from late in my PhD cycle through my post-PhD teaching career there, to work with Mary O'Rourke (and others) who were from that lab running an undergraduate tutorial. The tutorial is three or four faculty members each running two or three groups, with about five or six students in each group. These are students majoring in Biological Anthropology, who have already taken a class or two but are on their way into the research labs. The tutorial instructors' job is to turn these young and interested minds into the minds of proto-Anthropologists by carefully examining a different topic each week, looking at a combination of peer reviewed literature and secondary but excellent literature (back in those days, the former was easier to find).

So, I spent a lot of time hanging around with the Reproductive Ecology people (and, by the way, collecting some of their data in Zaire). Every social event had a lot of Repro Eco folks at it, so it was pretty normal for someone to pull out a box of specially prepared test tubes to get every one to provide saliva samples for some study or another. It was not long into the process of developing this subfield that the reproductive ecology of men, simpler but still important, was also taken up by this group, so everyone had an opportunity to spit into the tubes. For example:

Hypothesis: Testosterone in men varies over short time scales (of minutes, hours) during a poker game depending on which cards they are dealt, assuming the samples are not contaminated by ...

... oh, never mind, you get the picture.

Anyway, it was while I was a couple of years into my own graduate career when a young man from California showed up to study anthropology, with a particular interest in Biological Anthropology. It was Richard Bribiescas. Rick and I did not hang around a lot of time, because we were both busy, but we were good friends and broke bread (a euphemism for guzzling beer but there were also tacos and cheeseburgers) quite often.

When Rick got to Harvard, there was already a strong tradition of working to understand modern human problems in the Western world by examining modern human behavior and physiology in a variety of other societies, including foragers.

Many young men and women went to the field from that department, to work in Poland, Borneo, the Amazon, the Congo. Among those, very few attempted to work in the most difficult of conditions, in a rain forest with foragers. Of those who tried most retreated and picked another topic. A few persisted and continued to study this or that thing about one of the few remaining forager group son the planet. That's what I did, with the Efe. That's also what Rick did, with the Ache, of South America.

And, as a result of that, Rick produced a bunch of interesting peer reviewed papers, and eventually, a book that has been out for a while now called Men: Evolutionary and Life History. A number of books had been written about female reproductive ecology, but along the way, rick became the expert on male reproductive ecology, discovering that it is not as simple as one might expect. This book is the result of that achievement.

And now, Rick is an old guy. He must be at least 45. And, as such, he has turned his attention to a new but related topic: How do men age. And, the newly produced book that comes from this research to your book shelf is How Men Age: What Evolution Reveals about Male Health and Mortality

Do not buy or borrow some book on aging written by a web site, a fake MD, or some other charlatan. Read a book on aging (in men) that first appeared many times in the peer reviewed literature, written by Harvard Trained Yale Expert Richard Bribiescas.

Note the subtitle. This is about what evolution reveals about male health and mortality. Having taught along side him many times, and after all those beers, tacos, and cheeseburgers, I can tell you that Rick knows all about evolution, and of course, he is the world's leading expert on male reproductive ecology.

I put the Table of Contents below to give you and idea.

Rick is a great writer, and this book is fun to read.

Do the well known features of male aging have some sort of evolutonary advantage, as has been proposed for females? How much of male aging in the West is a function of our Western lifestyle, or a function of our seemingly extended lifespan? What about the contradiction between what we mere humans think of as "health" or "healthy" and what the cruel and cold process of Darwinian natural selection things about such silly things? What about sex, relationships, monogamy, polygamy, fatherhood and child rearing, in male humans in general, and across the aging process? And our brains, our obscenely large brains, what the heck are they for?

You will enjoy this book, especially if you are a man of a certain age.

Table of Contents:

Acknowledgments ix
Chapter 1 A Gray Evolutionary Lens 1
Chapter 2 Dead Man’s Curve 17
Chapter 3 Getting a Handle on Love Handles 45
Chapter 4 Older Fathers, Longer Lives 70
Chapter 5 Dear Old Dad 88
Chapter 6 Darwinian Health and Other Contradictions 106
Chapter 7 Older Men and the Future of Human Evolution 133
Notes 145
Index 169

gregladen Mon, 10/24/2016 - 05:05

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The cost of male pheromones

dr. dolittle — Fri, 16 Sep 2016 12:39:31 +0000

The cost of male pheromones

Video of C. elegans from Wikipedia. https://upload.wikimedia.org/wikipedia/commons/b/be/CrawlingCelegans.gif

A new study conducted by researchers at Northwestern University examined the costs of reproduction in roundworms, otherwise known as C. elegans. They discovered that male roundworms can send two kinds of pheromones that prime females for reproduction. One type of pheromone they studied sparks the onset of puberty in young female worms while the other prolongs fertility in aging females. The problem is that these changes come at a cost as it shortens the lifespan of female roundworms.

According to the study authors, a similar effect has been seen in mammals where a pheromone can change when females become sexually mature.

Since this effect appears common to roundworms and mammals, these findings raise the possibility that something similar might happen with humans. Thus the hope is to apply these findings to humans in an effort to prolong fertility...although I am not sure women would seek out this treatment if it increased aging.

Source:

Aprison EZ, Ruvinsky I. Sexually antagonistic male signals manipulate germline and soma of C. elegans hermaphrodites. Current Biology, 2016 DOI: 10.1016/j.cub.2016.08.024

dr. dolittle Fri, 09/16/2016 - 08:39

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Muscle Aging in American Quarter Horses

dr. dolittle — Tue, 28 Jun 2016 22:20:13 +0000

Muscle Aging in American Quarter Horses

Skeletal muscle function and structure change as we age. Humans typically experience a loss of muscle mass or muscle weakness which can greatly reduce mobility and stability. While much is known about aging skeletal muscle in humans and rodents, less is known about horses, which are rather athletic animals that are living longer due to advancements in veterinary care and retirement programs. Researchers from the University of Florida decided to explore how aging effects skeletal muscles of horses. To do this, they examined gluteus medius (speed and locomotion) and triceps brachii (mainly postural) muscles in sedentary Quarter Horses aged 2 years old (young) or 17-25 years old (i.e. aged). Their results were recently published in the Journal of Applied Physiology.

The team characterized the fiber type of each muscle as well as the number and function of mitochondria. With aging in humans and rodents, there is a decline in the function and/or number of these energy producing organelles. This video is a nice review of the muscle fiber types and role of mitochondria:

Examining muscle biopsies, the research team found that the number of mitochondria were decreased in the triceps, but not gluteal muscles with aging. They also found changes in the muscle fiber type with aging. A high proportion of type II fibers (like in gluteus muscle) gives horses their speed whereas more type I fibers play a role in maintaining posture (like in triceps). With aging, the gluteus muscle develops more type I fibers and the triceps muscle develops more type IIA fibers with less IIX fiber types in both muscles. Although the activities of some mitochondrial enzymes also declined with aging, it was not associated with a decline in mitochondrial function. The authors attributed this lack of measurable mitochondrial dysfunction to either the horses not being old enough for dysfunction to exist yet (20 years horse = about 65 years human) or perhaps that aging in horse skeletal muscle is different from that of rodents and humans. Either way, understanding how our equine friends age is fascinating.

Source:

Li C, White SH, Warren LK, Wohlgemuth SE. Effects of aging on mitochondrial function in skeletal muscle of Quarter Horses. Journal of Applied Physiology. Article in press June 9, 2016. doi: 10.1152/japplphysiol.01077.2015

dr. dolittle Tue, 06/28/2016 - 18:20

Tags

What about the role of the Hox genes, are there conserved between the species? It would be interesting to know if horses had them too, since we know they have an influence on muscle aging. We shortly discussed it in a article on Long Long Life : http://longlonglife.org

A dietary supplement to slow aging

gregladen — Fri, 17 Jun 2016 06:16:36 +0000

A dietary supplement to slow aging

This is great news if you are a mouse!

Here's the summary of the paper:

NAD+ repletion improves mitochondrial and stem cell function and enhances life span in mice, by
Hongbo Zhang, Dongryeol Ryu, Yibo Wu, Karim Gariani, Xu Wang, Peiling Luan, Davide D’Amico, Eduardo R. Ropelle, Matthias P. Lutolf, Ruedi Aebersold, Kristina Schoonjans, Keir J. Menzies, Johan Auwerx, (here, if you subscribe to Science.)

The oxidized form of cellular nicotinamide adenine dinucleotide (NAD+) is critical for mitochondrial function, and its supplementation can lead to increased longevity. Zhang et al. found that feeding the NAD+ precursor nicotinamide riboside (NR) to aging mice protected them from muscle degeneration... NR treatment enhanced muscle function and also protected mice from the loss of muscle stem cells. The treatment was similarly protective of neural and melanocyte stem cells, which may have contributed to the extended life span of the NR-treated animals.

Writing in Science, Leonard Guarente notes:

NAD was discovered over a century ago, and its role in cells as a redox conduit in metabolism was subsequently established. More recently, its oxidized form, NAD+, resurfaced as a key molecule in aging in organisms ranging from yeast to mammals by the finding that the antiaging proteins, sirtuins, are NAD+-dependent deacylases. These proteins play a key role in mitochondrial function. Indeed, aging is also associated with loss of sirtuin and mitochondrial function.

As to whether NAD+ replenishment can improve health maintenance in humans, it has been reported that cellular NAD+ amounts decline during human aging (11). Also, the strict conservation in the relevant pathways of NAD+ synthesis, sirtuins, and PARPs suggests that NAD+ replenishment may also provide health benefits in people. Still, it will be important to test in humans whether dietary supplementation with NAD+ precursors will raise cellular NAD+ concentrations sufficiently to compensate for the loss due to aging. If so, it will also be necessary to test, in rigorously controlled trials, whether raising NAD+ concentrations improves health parameters, such as blood glucose and lipid profile, as well as inflammation. More expanded trials could measure effects on bone density, endothelial cell function, muscle mass, or even cognition. If NAD+ precursors can positively affect health parameters, it is reasonable to anticipate their place at the table alongside more traditional pharmaceutical drugs in the treatment of diseases.

And yes, you can buy this stuff.

But before you do that you may want to check out some of the writing that comes up from the Skeptical Search Engine.

gregladen Fri, 06/17/2016 - 02:16

Tags

Here's the thing about mice--they don't have the same energy metabolism as humans. Mice are geared to reproduce quickly--if you give mice enough food, you don't get fat mice, you get more little mice. Mice are terrestrial tribbles.

Since mice have not been optimized for long life, there are a lot of tweaks that can be made to increase their lifespan. Humans are much better optimized for longevity, and it is unlikely that things which improve the lifespan of a mouse will have much effect on humans.

Problem is, of course, that testing with more relevant model systems (long-lived primates like us) just takes too much time. Guarante is already in his 60s and can't wait. (He looks it too, makes me wonder.....) His statement above is ironic given that he founded Elysium health, which is going the "promote it for quick bucks" supplement route for an NAD precursor, not the clinical trials route--at least, there's no mention of trials on Elysium's website.

Indeed, mice are way different. On the other hand, this supplement seems, at least, not too expensive and seems not dangerous, so maybe it won't be too hard to get some reasonable data in testing.

Worth reading: Survival, harassment, and independence

lborkowski — Mon, 14 Dec 2015 10:06:06 +0000

Worth reading: Survival, harassment, and independence

A few of the recent pieces I've liked:

Alana Semuels in The Atlantic: How Poor Single Moms Survive

Nina Martin of ProPublica interviews David Cohen: For Abortion Providers, a Constant Barrage of Personalized Harassment

Terry Fulmer at the Health Affairs Blog: Independence -- It's What Older People Want

Charles D. Ellison at The Root: Wake Up, Black People. The Supreme Court Is Poised to Drop a Bomb on You

Vanessa Heggie in The Guardian: World AIDS Day: How AIDS activists changed medical research (also, it's not a new publication, but World AIDS Day was a good opportunity to re-read this excerpt from Maryn McKenna's book Beating Back the Devil).

lborkowski Mon, 12/14/2015 - 05:06

Tags

Public Health - General

Aging: Even Opie. An evolutionary perspective

gregladen — Mon, 23 Nov 2015 07:23:18 +0000

Aging: Even Opie. An evolutionary perspective

I'm not going to say that Ron Howard is old or anything, but he isn't Opie any more. (And, in fact, it has been fascinating and inspiring to watch his career, by the way.) Anyway, Howard produced a new documentary with National Geographic called "Breakthrough: The Age of Aging, which premieres Sunday, November 29 at 9 pm et on National Geographic Channel. And, pursuant to this, National Geographic's web site is sponsoring a Roundtable on the topic. The roundtable addresses the question, "By treating aging as a disease are we just prolonging the inevitable or can we change the course of our lives?"

The short answer to this is, I'm not really sure, but I think it is helpful to put aging, and changes in human patterns of aging, in a broader anthropological and evolutionary perspective.

LOS ANGELES - Priya Balasubramanian studies the science of aging.  (photo credit: Asylum Entertainment)

People have long lived long, even hunter gatherers in the Stone Age, as to modern hunter gatherers. In fact, hunter gatherers may have had longer and healthier lives than some of their errand cousins who went and invented agriculture and animal husbandry. In some cases we know from archaeology that populations engaged in early experiments with agriculture experienced dramatic decreases in overall health, and presumably, life span. This may have been a combination of larger groups sharing more diseases, unsanitary conditions developing in a more settled lifestyle, and a diet based on a smaller range of foods one ends up when casting off the foraging way of life. Eventually, in regions where this has been observed, things got better, either as a result of cultural adaptation or genetic changes.

When we look into the past, it is too easy to compress our ancestry into a caricature of primitive humanity, and based that conception on the wrong model. For example, it is said that "people were shorter back then." Often, that is true, but the shorter people were actually poor urban dwellers in late medieval European settlements where diet was poor and disease demanded more energy of the immune system than average, so growth was sacrificed. If we look at pre-agricultural foraging populations, we often see relatively tall people. This is a bit enigmatic because so many modern forager groups are short statured. The explanation for that is probably that forager groups who are still around today, or have been extant over the last century or so, eek out their existence in relatively marginal habitats, the better parts of the landscape taken over by farmers and herders.

___
See: “If this was the Stone Age, I’d be dead by now”
___

So, we should expect that prehistoric lifespan varied across time and space, and as I noted, there were probably always elderly people, but just not too many of them, compared to today. It has become axiomatic to note in modern day conversations that many of our diseases, in the West, are "diseases of civilization." This is a combination of health effects, but one of the most important is the lack of disease of the past because they have been addressed, at least for now, at least for a subset of the human population. Antibiotics alone probably allow a much larger proportion of the human population to survive long enough to experience age-related disease.

A good part of Howard's documentary is about the science of aging. We want our scientists to figure out how to beat aging, or at least, slow it down. But this is not easy. Humans are primates, and primates are mammals. The very earliest mammals probably evolved to die young. That seems counterintuitive but it really isn't. Life History Theory predicts that organisms will be selected to produce some sort of balance (or bias, imbalance) of three major energy shunting systems: growth, maintenance (including the immune system), and reproduction. Humans reproduce slowly, producing one (or two) offspring at a time, and putting a lot of effort into each one. This goes along with a long lifespan, because in order to produce a small number of high-quality offspring one must take some time. This, however, places additional demands on the immune system. In order to keep up with evolving microbes and the overall ravages of time, we need to spend a fair amount of effort on keeping from being too sick. And, we happen to be large, for a primate. That probably relates to predator pressure and a few other factors. So while we are selected to live a long time compared to the average primate (and certainly, the average mammal) we can only go just so far.

But perhaps more importantly, we (humans, and to a somewhat lesser extent, primates in general) are modified versions of mammals, and there are indications that mammals were never originally designed (by natural selection) to live long lives. Early mammals were probably small, and small goes along with a short lifespan in the mammalian world. Remember, those early mammals were living along side dinosaurs! (There were large early mammals but modern mammals, including all the more recent large one, probably evolved from a subset of them that were on the small side.) In a world where the smallest dinosaurs were larger than the largest mammals (or close to that) mammals were probably more often prey than predator. The best strategy if the most likely cause of death is being scarfed up by something larger is to live fast, have one or two litters of offspring, and do the whole "circle of life" thing really fast.

___
See: How Long Is A Human Generation?
___

One strong piece of evidence that a live fast and die young strategy applied to early mammals is the fact that mammal females are born already containing all the egg cells they will ever produce. This is the primary determinant of reproductive lifespan for human females. Organisms that are born ready to reproduce tend to have that strategy of rapid early reproduction followed by an early death. One of the more extreme examples of this is aphids. Aphids have two modes of reproduction, but in one of them, female aphids are born gravid. While human females are not born pregnant, they are born with the eggs ready to go.

Not only have humans (following the primate lead) extended their lifespan and slowed down their reproduction, but they ave added, apparently, another phase of life: Post reproductive. Human females in foraging societies around the world are productive members of their families after they have stopped being fertile. This seems to not make sense from a Darwinian perspective. Why not just keep reproducing until you die? Probably for two reasons. First, they can't, because human lifespans are already extended to the limit of our phyolgeneticaly constrained abilities. Second, that post-reproductive period probably enhances Darwinian fitness. Studies have shown that elder women in foraging societies contribute significantly to the health and wellbeing of their own children's offspring. Grandmothers are an adaptation!

gregladen Mon, 11/23/2015 - 02:23

Tags

behavioral biology

aging

Hunter-gatherers

National Geographic documentary

Guest Post: A time for everything – but speed it up, please!

jhalper — Mon, 12 Oct 2015 04:41:13 +0000

Guest Post: A time for everything – but speed it up, please!

Ziv Zwighaft

Ziv Zwighaft is a research student in the group of the Weizmann Institute’s Dr. Gad Asher. Their new findings reveal some intriguing connections between our circadian clocks – which tick according to cycles of day and night – metabolism and aging. Here is his description:

King Solomon said: “There is a time for everything, and a season for every activity under the heavens.”

Our research tries to take this insight into the condition of living creatures a few strides forward. How strictly does it apply? Our lives are regulated by a biological clock – it’s actually many clocks working in synergy, orchestrating our waking, sleeping and eating, our growth and life stages and, recent research suggests, our metabolism. So first and foremost, the new findings are strong support for the claim that our circadian clocks are strongly intertwined with our body’s metabolic activities. We showed that the daily changes in the levels of a group of essential metabolites called polyamines are regulated from two sides – both by eating times and by the ticking of the clock. Polyamines are naturally occurring metabolites that are known to play a role in various essential cellular processes, as well as pathologies. Our research shows that they also play an active role in setting the tempo of our internal timing. (The research revealed that polyamines both regulate and are regulated by a circadian clock. WSW)

Dysfunction in the clock can lead to a wide range of diseases, starting with sleep disorders and on to metabolic disorders like obesity and diabetes, and up to psychological illnesses.

One of the things I found most encouraging was our success in reproducing the results we obtained in tissue culture and raising them to the level of the whole animal. Here, a deviation from the natural polyamine levels translated into clock malfunction. For example, low levels of polyamines made the clock run slow, and this situation was reversible by enriching the diet with polyamines.

This phenomenon – a drop in polyamine levels and impairment in the clock’s accuracy – is typical of the process of aging. So by investigating the joins between two worlds – circadian clocks and metabolism – we able to demonstrate how to “rejuvenate” the internal pace of timekeeping in old mice.

This particular study is finished, but the work has not been completed. In these days we are continuing to look for additional connections between the circadian clocks and metabolic processes in the body; these connections may lead to new strategies in the war against age-related disease.

So bad news and good: On the one hand, polyamine levels of tend to drop as we age, and our internal clocks lose time. On the other hand, we get polyamines from food too. When the researchers added a polyamine supplement to the diets to old mice, their slow circadian clocks gained minutes.

Asher says that much more research will be needed before we can tell whether such food supplements will have an effect on aging in humans. In the meantime, however, it can’t hurt to stick to a healthy diet and add some extra edamame, peas or lentils to the menu.

jhalper Mon, 10/12/2015 - 00:41

Tags

basic research

biochemistry

biological regulation

biological regulation

circadian clocks

obesity

Hm?
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3022763/
doi: 10.3402/fnr.v55i0.5572

"... On the other hand, the cell growth promoting effect may also be negative in relation to cancer development. It has been shown that increased polyamine levels are associated with increased cell proliferation as well as expression of genes affecting tumor invasion and metastasis (21)."

Dear Hank,

You are right, elevation in polyamine levels had been previously linked with cancer development. With that been said, in our research we restored the polyamine levels to basal levels and worked well inside the physiological range and far from the pathological concentrations. Like many things in life, too much or too little from something might hurt you...

Thank you for commenting, hope you enjoyed our project.

Ziv

The fact it can cause cancer is pretty scary.

Worth reading: Older Americans, unplanned births, and workers' fights

lborkowski — Mon, 09 Mar 2015 10:44:15 +0000

Worth reading: Older Americans, unplanned births, and workers' fights

A few of the recent pieces I've liked:

Two related pieces at ReportingonHealth.org: Rita Beamish, "Older Americans Act limps along at 50" and Ryan White, "Intensive program keeps elderly at home out of nursing home"

Gillian B. White in The Atlantic: Unplanned Births: Another Outcome of Economic Inequality?

Mike Paarlberg in the Washington City Paper: Workers' Fights ("Unpaid wages, uncompensated injuries, and unjust firings: A look at the margins of the DC labor market")

Nikole Hannah-Jones in Politico Magzine: A Letter from Black America: Yes, we fear the police. Here's why.

Erika Check Hayden in Nature: Maternal health: Ebola's lasting legacy

And Celeste already blogged about this one, but the excellent and terrifying ProPublica-NPR series Insult to Injury: America's Vanishing Worker Protections is a wake-up call to anyone who assumes the workers' comp system will support you if you're injured on the job. Simultaneously with this series' publicaiton and airing, OSHA released the report Adding Inequality to Injury: The Costs of Failing to Protect Workers on the Job, and Lydia DePillis covered it for Wonkblog.

lborkowski Mon, 03/09/2015 - 06:44

Tags

Public Health - General

workers' compensation

Wednesday: Grand Challenges in Physiology

dr. dolittle — Fri, 10 Oct 2014 17:13:31 +0000

Wednesday: Grand Challenges in Physiology

Image from the American Physiological Society's website.
http://www.the-aps.org/mm/Conferences/APS-Conferences/2014-Conferences/…

Wednesday was the last day of the meeting that culminated in a closing banquet with an awards session to honor students who had exceptional presentations. What an impressive group of young comparative physiologists! The plenary lecture was given by Dr. Steven Chown (Monash Univ, Australia). He spoke about climate change forecasts and continuing environmental changes and how important it is to understand how animals adapt to changing conditions in order to make ecophysiological predictions.

Other highlights from throughout the final day of the meeting included:

A series of lectures that were focused on understanding and modeling responses to stress in animals to help predict when populations may be at risk of declining before it happens.

Finkelstein A, Derdikman D, Rubin A, Foerster JN, Las L, Ulanovsky N (Weizmann Inst of Sci; Israel Inst of Tech). There are neurons in brain that are called 'head-direction cells'. These are responsible for informing an animal when their head is oriented in a specific direction, which is important for orientation when navigating in a three-dimensional space.

Dr. John Cockrem (Massey Univ, New Zealand) spoke about how birds release the hormone corticosterone when they perceive or experience a threat. This response to stress can vary between birds. Birds that have lower stress responses (indicated by lower corticosterone release) are considered to be more successful under predictable conditions. In contrast, birds with large stress responses may be more successful under unpredictable or changing conditions, which may help them to deal with environmental changes better than birds with lower stress responses.

13-lined ground squirrel hibernation is broken up by intermittent bouts of arousal during which time the animal wakes up from torpor (See figure below).

Figure 1: showing hibernation of a 13-line ground squirrel with intermittent bouts of arousal and torpor. March 16, 2009, doi:
10.1113/jphysiol.2008.167692

Ballinger M, Napolitano M, Bjork J, Andrews MT (Univ Minnesota) discussed how brown fat (i.e. brown adipose tissue), which the animals build up before hibernation, is important for producing heat that enables them to have these intermittent bouts of arousal. Notice in the image above how the body temperature ranges from ~37degC when they are awake down to only about 3-5degC when they are in torpor.

Grabek K, Hesselberth J, Barsh G, Behn CD, Martin S (Univ Colorado (Denver); HudsonAlpha Inst Biotech) also discussed how brown fat cycles between a more dormant state (torpor) to an active state (arousal) to match the metabolism of the whole animal during those phases. They discovered that the genome of the brown fat actually changes during these different phases to allow for the rapid production of various proteins needed to produce heat (thermogenesis).

Wone B, Ojha J, Davidowitz (Univ Nevada-Reno; Univ Arizona) presented data that showed hawkmoths (Manduca sexta) are good models of disease and aging in skeletal muscle because their flight muscles are similar, metabolically-speaking, to vertebrate skeletal muscle. Who knew?

Image of Manduca sexta from Wikimedia Commons.

dr. dolittle Fri, 10/10/2014 - 13:13

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