In a small clean room tucked into the back of San Diego–based startup Organovo, Chirag Khatiwala is building a thin layer of human skeletal muscle. He inserts a cartridge of specially prepared muscle cells into a 3-D printer, which then deposits them in uniform, closely spaced lines in a petri dish. This arrangement allows the cells to grow and interact until they form working muscle tissue that is nearly indistinguishable from something removed from a human subject.

The technology could fill a critical need. Many potential drugs that seem promising when tested in cell cultures or animals fail in clinical trials because cultures and animals are very different from human tissue. Because Organovo’s product is so similar to human tissue, it could help researchers identify drugs that will fail long before they reach clinical trials, potentially saving drug companies billions of dollars. So far, Organovo has built tissue of several types, including cardiac muscle, lung, and blood vessels.

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“Rare-earth magnets!” Cohn cried, straining to pull one free. He put it in my hand. It was the size of a pencil eraser, and when I loosened my grip, it shot like a bullet to the file cabinet with a clang. “Extremely powerful.” Cohn has pioneered the use of rare-earth magnets to move catheters into place deep inside the body. He avoids having to cut patients open by threading the magnets, and their tiny loads, up through arteries. He pawed several sheets of paper off the floor and drew diagrams on their unused backs, launching an hour-long discourse on the instruments and procedures he’s built around miniature magnets.

Building a heart that mimics nature’s lub-dub may be as comically shortsighted as Leonardo Da Vinci designing a flying machine with flapping wings.On his wall hung four metal serving spoons of the kind you might see on a cafeteria line. One was intact; the other three had intricate slots cut in them. Years ago, Cohn butchered the spoons in his home garage to solve the problem of holding a heart still while operating on it. The standard way, at the time, was to shut off the heart altogether and put the patient on a heart-lung machine. But that was risky. Cohn’s spoons let surgeons hold a heart in place while still giving them access to the parts they needed to slice or stitch. Through the custom-cut slots, the surface of the heart would emerge and hold still for tinkering, even while the rest of the heart thrashed around under the spoon. Cohn refined the idea and sold it to a medical-devices company, which has marketed the tools worldwide.

I love genius/crazy scientists who push forward the state of the art.

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While researchers have known for decades that the body undergoes various metabolic and hormonal changes while it’s losing weight, the Australian team detected something new. A full year after significant weight loss, these men and women remained in what could be described as a biologically altered state. Their still-plump bodies were acting as if they were starving and were working overtime to regain the pounds they lost. For instance, a gastric hormone called ghrelin, often dubbed the “hunger hormone,” was about 20 percent higher than at the start of the study. Another hormone associated with suppressing hunger, peptide YY, was also abnormally low. Levels of leptin, a hormone that suppresses hunger and increases metabolism, also remained lower than expected. A cocktail of other hormones associated with hunger and metabolism all remained significantly changed compared to pre-dieting levels. It was almost as if weight loss had put their bodies into a unique metabolic state, a sort of post-dieting syndrome that set them apart from people who hadn’t tried to lose weight in the first place.

… Another way that the body seems to fight weight loss is by altering the way the brain responds to food. Rosenbaum and his colleague Joy Hirsch, a neuroscientist also at Columbia, used functional magnetic resonance imaging to track the brain patterns of people before and after weight loss while they looked at objects like grapes, Gummi Bears, chocolate, broccoli, cellphones and yo-yos. After weight loss, when the dieter looked at food, the scans showed a bigger response in the parts of the brain associated with reward and a lower response in the areas associated with control. This suggests that the body, in order to get back to its pre-diet weight, induces cravings by making the person feel more excited about food and giving him or her less willpower to resist a high-calorie treat.

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The crucial new idea is that there are two different neural and psychological systems that interact to turn children into adults. Over the past two centuries, and even more over the past generation, the developmental timing of these two systems has changed. That, in turn, has profoundly changed adolescence and produced new kinds of adolescent woe.

… The first of these systems has to do with emotion and motivation. It is very closely linked to the biological and chemical changes of puberty and involves the areas of the brain that respond to rewards.

… The second crucial system in our brains has to do with control; it channels and harnesses all that seething energy. In particular, the prefrontal cortex reaches out to guide other parts of the brain, including the parts that govern motivation and emotion. This is the system that inhibits impulses and guides decision-making, that encourages long-term planning and delays gratification.

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“I believe if we look at people at the molecular level we can improve their health,” says Sylvia Daunert, Ph.D., chair of the Department of Biochemistry and Molecular Biology at the UM Medical School. The studies question long-held beliefs about food selection and weight loss. For example, could 1,000 calories of turkey cause more weight gain in some people than 1,000 calories of cashews? If so, could a person lose weight through food selection without cutting total calories?

And could a person’s genes pre-determine whether he or she will benefit from a particular type of exercise – or perhaps be at greater risk of injury from it?

UM researchers are looking into it. “We can’t say this is 100 percent correct,” Daunert says. “This is our hypothesis. This is brand-new science.”

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In a study that provides provocative support for a new approach to treating obesity, a drug that kills a particular type of fat cell by choking off its blood supply was shown to cause significant weight loss in obese monkeys.

After four weeks of treatment at M.D. Anderson Cancer Center in Houston, obese monkeys given daily injections of the drug, called adipotide, lost an average of 11% of their body weight. They also had substantial reductions in waist circumference and body-mass index and, importantly, striking improvement in the ability to respond to insulin, researchers said. The drug didn’t have any effect on weight when given to lean monkeys.

Results of the study, published online Wednesday by the journal Science Translational Medicine, confirmed a 2004 report from the same research team showing marked weight loss in mice treated with the agent.

My first reaction was: “I want to take this drug”. My second reaction was “I should invest in this drug. Everyone is going to want to take it.”

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In my favorite of these studies, children were divided into two groups. All of them were given a sugar-free beverage to drink. But half the parents were told that their child had just had a drink with sugar. Then, all of the parents were told to grade their children’s behavior. Not surprisingly, the parents of children who thought their children had drunk a ton of sugar rated their children as significantly more hyperactive. This myth is entirely in parents’ heads. We see it because we believe it.

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If Aubrey de Grey’s predictions are right, the first person who will live to see their 150th birthday has already been born. And the first person to live for 1,000 years could be less than 20 years younger.

A biomedical gerontologist and chief scientist of a foundation dedicated to longevity research, de Grey reckons that within his own lifetime doctors could have all the tools they need to “cure” aging — banishing diseases that come with it and extending life indefinitely.

“I’d say we have a 50/50 chance of bringing aging under what I’d call a decisive level of medical control within the next 25 years or so,” de Grey said in an interview before delivering a lecture at Britain’s Royal Institution academy of science.

“And what I mean by decisive is the same sort of medical control that we have over most infectious diseases today.”

De Grey sees a time when people will go to their doctors for regular “maintenance,” which by then will include gene therapies, stem cell therapies, immune stimulation and a range of other advanced medical techniques to keep them in good shape.

Stephen Guyenet recently reviewed the literature. He found that there is very little evidence that diets high in saturated fats give you high cholesterol.

The earliest and perhaps most interesting study I found was published in the British Medical Journal in 1963 and is titled “Diet and Plasma Cholesterol in 99 Bank Men” (4). Investigators asked volunteers to weigh all food consumed at home for 1-2 weeks, and describe in detail all food consumed away from home. Compliance was good. This dietary accounting method was much more thorough than in most observational studies today**. Animal fat intake ranged from 55 to 173 grams per day, and blood cholesterol ranged from 154 to 324 mg/dL, yet there was no relationship whatsoever between the two. I’m looking at a graph of animal fat intake vs. blood cholesterol as I write this, and it looks like someone shot it with a shotgun at 50 yards. They twisted the data every which way, but were never able to squeeze even a hint of an association out of it.

…

Overall, the literature does not offer much support for the idea that long term saturated fat intake has a significant effect on the concentration of blood cholesterol. If it’s a factor at all, it must be rather weak, which is consistent with what has been observed in multiple non-human species (13).

I found another interesting analysis, published last January in the American Journal of Clinical Nutrion. In it, the authors did a meta-analysis of lots of other studies. They also concluded that there is very little relationship between the fat in your diet and the fat (cholestrol) in your blood.

BACKGROUND: A reduction in dietary saturated fat has generally been thought to improve cardiovascular health.

OBJECTIVE: The objective of this meta-analysis was to summarize the evidence related to the association of dietary saturated fat with risk of coronary heart disease (CHD), stroke, and cardiovascular disease (CVD; CHD inclusive of stroke) in prospective epidemiologic studies.

DESIGN: Twenty-one studies identified by searching MEDLINE and EMBASE databases and secondary referencing qualified for inclusion in this study. A random-effects model was used to derive composite relative risk estimates for CHD, stroke, and CVD.

RESULTS: During 5-23 y of follow-up of 347,747 subjects, 11,006 developed CHD or stroke. Intake of saturated fat was not associated with an increased risk of CHD, stroke, or CVD. The pooled relative risk estimates that compared extreme quantiles of saturated fat intake were 1.07 (95% CI: 0.96, 1.19; P = 0.22) for CHD, 0.81 (95% CI: 0.62, 1.05; P = 0.11) for stroke, and 1.00 (95% CI: 0.89, 1.11; P = 0.95) for CVD. Consideration of age, sex, and study quality did not change the results.

CONCLUSIONS: A meta-analysis of prospective epidemiologic studies showed that there is no significant evidence for concluding that dietary saturated fat is associated with an increased risk of CHD or CVD. More data are needed to elucidate whether CVD risks are likely to be influenced by the specific nutrients used to replace saturated fat.

Once you know about sitters and rovers, you see them everywhere, especially among young children. Drop in on your local Mommy and Me music class: there are the sitters, intently watching the action from their mothers’ laps, while the rovers march around the room banging their drums and shaking their maracas.

Relaxed and exploratory, the rovers have fun, make friends and will take risks, both rewarding and dangerous ones, as they grow. According to Daniel Nettle, a Newcastle University evolutionary psychologist, extroverts are more likely than introverts to be hospitalized as a result of an injury, have affairs (men) and change relationships (women). One study of bus drivers even found that accidents are more likely to occur when extroverts are at the wheel.

In contrast, sitter children are careful and astute, and tend to learn by observing instead of by acting. They notice scary things more than other children do, but they also notice more things in general. Studies dating all the way back to the 1960’s by the psychologists Jerome Kagan and Ellen Siegelman found that cautious, solitary children playing matching games spent more time considering all the alternatives than impulsive children did, actually using more eye movements to make decisions. Recent studies by a group of scientists at Stony Brook University and at Chinese universities using functional M.R.I. technology echoed this research, finding that adults with sitter-like temperaments looked longer at pairs of photos with subtle differences and showed more activity in brain regions that make associations between the photos and other stored information in the brain.

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