Author Archives: Francesca Schiopca

You can now add pasta to your list of healthy diet foods, study suggests

Nowadays, people tend to blame carbohydrates for the obesity epidemic, but a new paper suggests that not all refined carbs — that are quickly absorbed into the bloodstream — make you fat. Pasta, for example, in spite of being a member of the refined carbohydrate family, has a low glycemic index (GI).

Via Pixabay/marker_photography

The glycemic index is the number that shows the effect of carbohydrates on a person’s blood sugar concentration. The glycemic index is usually applied in the context of the quantity of the food ingested and the amount of carbohydrate present in the food.

Another measure, the glycemic load (GL), factors this in by multiplying the glycemic index of the food in question by the carbohydrate content of the actual serving. For example, watermelons have a high glycemic index, but a low glycemic load for the quantity typically consumed. Fructose, however, has a low glycemic index but can have a high glycemic load if a large quantity is ingested. In other words, it’s not always tit for tat with these two parameters.

Researchers analyzed data from 30 randomized control trials involving almost 2,500 people who ate pasta, instead of other carbohydrates, as part of a healthy low-glycemic index diet.

“The study found that pasta didn’t contribute to weight gain or increase in body fat,” said lead author Dr. John Sievenpiper, a clinician scientist from the St. Michael’s Hospital’s Clinical Nutrition and Risk Modification Centre. “In fact, analysis actually showed a small weight loss. So contrary to concerns, perhaps pasta can be part of a healthy diet such as a low GI diet,” he added.

Participants involved in the trials ate on average 3.3 servings of pasta per week instead of other carbs, one serving of pasta meaning one-half cup of boiled pasta. At the 12-week follow-up, scientists observed that participants had lost 0.5 kilos on average.

Although pleased by the findings, researchers highlighted that these results are generalizable to pasta consumed along with other low-glycemic index foods as part of a low-glycemic index die

“In weighing the evidence, we can now say with some confidence that pasta does not have an adverse effect on body weight outcomes when it is consumed as part of a healthy dietary pattern,” said Dr. Sievenpiper.

I, for one, couldn’t be any happier. As a pasta lover, and a health freak, this news is incredible. The only thing left for me to say is ‘Buon appetito’!

The paper was published in the journal BMJ Open.

 

Marijuana legalization helps decrease opioid consumption, research shows

Every day, 90 Americans die from opioid overdoses, according to existing research. Two new studies published in the journal JAMA Internal Medicine now show that in states where marijuana is legal, opioid prescriptions decreased significantly.

Image credits Flickr / Jeffrey Beall.

Researchers have analyzed prescription data from Medicare Part D and Medicaid from the past five years and discovered that opioid prescriptions and the average daily dose of opioids patients took were significantly lower in areas where marijuana is legal.

“In this time when we are so concerned — rightly so — about opiate misuse and abuse and the mortality that’s occurring, we need to be clear-eyed and use evidence to drive our policies,” said W. David Bradford, an economist at the University of Georgia and an author of one of the studies.

“If you’re interested in giving people options for pain management that don’t bring the particular risks that opiates do, states should contemplate turning on dispensary-based cannabis policies.”

Previous research suggests the same. A 2014 paper discovered that in states where cannabis use is legal for medical purposes, nearly 25 percent fewer deaths from opioid overdoses occurred.

One of the studies revealed that Medicare patients filled 14% fewer opioid prescriptions after medical cannabis use became legal. The other study, which monitored Medicaid opioid prescriptions, found that participants filled nearly 40 fewer opioid prescriptions per 1,000 people (4%) each year after their state passed laws that made cannabis accessible — states that legalized both medical and recreational marijuana showed greater falls in opioid prescriptions.

With the arrival of fentanyl on the black market, doctors fear we’ll see even more cases opioid overdose. This powerful opioid is up to 100 times more potent than morphine. Due to its powerful effect, fentanyl doses are very small, which is actually a problem. Overdoses usually occur when miscalculating the amount of drug administered, and it’s easier to go wrong with smaller doses. When fentanyl became a go-to drug for dealers, opioid deaths immediately spiked due to its high potency at low doses. Basically, people did not know that surpassing the dosage with only a few micrograms might be fatal.

So, the findings seem positive from a public health point of view. Marijuana is generally perceived as ‘safe’, and according to The National Center for Biotechnology Information, there is insufficient evidence to support or refute a statistical association between cannabis use and death due to cannabis overdose — in other words, there’s not enough data to say that cannabis use can or cannot be fatal, which, relative to fentanyl, makes it super-duper safe.

One recent paper even suggested that opioids didn’t provide any more relief for chronic arthritis pain than over-the-counter painkillers.

The studies also discovered differences in decline in opioid prescription between the states that legalized medical marijuana: states with dispensaries open for business saw the greatest decrease in opioid prescriptions, while states without active dispensaries saw a far less dramatic decline — about 14% and 7%, respectively

Bradford said that this made sense. The difference between picking up ready-to-use marijuana and growing your own plant with little support from the authorities is huge.

One impediment in substituting opioids with marijuana is that neither Medicaid nor Medicare will reimburse people for the money they spend on marijuana.

“I did a back-of-the-envelope calculation that suggested that a daily pain management dose of hydrocodone would be about $10 out of pocket in the U.S,” Bradford said, although Medicare Part D plans cover much of that.

Last year, a daily dose of marijuana cost around $6 — and that sum should be smaller by now, Bradford said. “It’s becoming relatively comparable in cost.”

“I know policymakers are often skeptical of cannabis. But we need to be terrified of things like fentanyl, and we need to be willing to use evidence-based approaches to help address that,” Bradford added. “Cannabis looks like it could be one,” he concluded.

Almost 40% of at-home DNA tests are inaccurate, scientists warn

A new study has found that at-home DNA testing kits are wrong 40% of the time.

Via Pixabay/geralt

For those who haven’t heard of them, direct-to-consumer genetic tests are genetic tests available that offer information about one’s ancestors, risks of certain diseases, and other traits, such as eye color. The demand for this kind of genetic tests has increased recently, along with the number of people interested in personalized healthcare. However, at-home DNA tests shouldn’t be taken as diagnostic because they only offer risk information for a small number of conditions.

Companies like 23AndMe and DNA Direct sell genetic tests that allegedly determine descendence or diagnose genetic predispositions in a person’s genetic makeup, but their results are highly questionable.

A new paper written by researchers at diagnostics company Ambry Genetics emphasizes that false positives are one of the greatest weaknesses of these kinds of at-home tests.

Stephanie Mlot from Geek.com made an excellent analogy: one’s genome is like a book about a person, with each gene representing a different chapter, and their DNA sequence serving as the letters that constitute the words. A genetic test performed in a professional lab will be able to read each word in specific chapters, checking if large sections aren’t missing or duplicated. Direct-to-consumer (DTC) tests, however, use a method called SNP array, reading only specific letters but not whole chapters.

“Many of these DTC labs also release raw data to the consumer,” wrote Stephany Tandy-Connor in a blog post. She is a genetic counselor for Ambry Genetics.

After a thorough look, researchers at Ambry Genetics reported that at-home DNA tests have a 40 percent false-positive.

“Our results demonstrated a 40% false positive rate highlighting the importance of confirming DTC raw data alterations in a clinical laboratory that is experienced in complex alteration detection and classification, especially prior to making any medical management recommendations,” added Tandy-Connor.

There is nothing wrong with wanting to be aware of your vulnerabilities, but DTC tests might not be the best way to discover them. Tests that provide incomplete genetic data are potentially harmful, and might lead to inappropriate changes in customer’s healthcare, researchers say.

“It is our hope that confirmatory testing and appropriate clinical management by all health-care professionals accompany DTC genetic testing for at-risk patients,” the authors concluded.

Eating out linked with hormonal disruptions, researchers say

A new study has discovered that eating out may increase exposure to harmful chemicals that are used to increase plastic’s flexibility and durability. Scientists believe that these chemical substances may cause hormonal imbalances.

Via Pixabay/StockSnap

Researchers have measured the blood levels of phthalates — binding agents frequently used in food packaging, adhesives, personal hygiene products, even flooring — and discovered that people who had eaten out in the previous day had 35% higher levels of phthalates than the participants who ate at home.

Recent studies associate phthalates with asthma, breast cancer, type 2 diabetes and fertility issues. Fortunately, the US has banned some of these nasty substances from children’s products.

According to the study, foods like burgers and sandwiches were at the top of the list when it came to high phthalate levels, but only if bought at a fast-food outlet, restaurant or cafe.

The research team observed that teenagers were the most affected age-group: teens who frequently consumed fast-food while out with their friends had 55% higher levels of the chemicals than young people who ate home-made food.

“This study suggests food prepared at home is less likely to contain high levels of phthalates, chemicals linked to fertility problems, pregnancy complications and other health issues. Our findings suggest that dining out may be an important, and previously under-recognised, source of exposure to phthalates for the US population,” said Researcher Dr Ami Zota, from George Washington University in Washington DC.

Researchers analyzed data from the US National Health and Nutrition Examination Survey (NHANES). A number of 10,253 participants provided information regarding what they ate and where their food came from over the past 24 hours. Next, scientists measured the phthalate levels found in each participant’s urine.

Participants reported that 61% of them ate out the previous day. Researchers demonstrated a significant association between phthalate exposure and dining out for all age groups, but concluded that young people showed the strongest one.

“Pregnant women, children and teens are more vulnerable to the toxic effects of hormone-disrupting chemicals, so it’s important to find ways to limit their exposures,” said lead author Dr Julia Varshavsky, from the University of California at Berkeley. “Future studies should investigate the most effective interventions to remove phthalates from the food supply,” she concluded.

The paper was published in the journal Environment International.

Researchers develop octopus skin-inspired infrared camouflage

Octopods are great at camouflage — they even surpass the ability of chameleons. But how does their camouflage system work?

The secret is chromatophores – skin cells that contain different pigments that are wired to the nervous system and to a radial muscle structure that allows it to change in length and thus change the color saturation of the cell. Each chromatophore is linked to the nervous system by a neuron, making the color change happen in less than a second.

 

They are also able to mimic textures via projections on the skin named papillae and can mirror the environment through iridophores —- reflective cells found in the octopi’s skin tissue.

Scientists have long been trying to develop the perfect camouflage system. Even though they succeeded to make objects invisible to the naked human eye, infrared cameras, that allow us to see temperature variations in colors would still be able to detect them because the electrical components that made visual camouflage possible would heat up, demonstrating their bluff.

So, researchers tried to imitate Mother Nature’s design: the octopod’s chromatophores. By combining special electrodes, wrinkled membranes, and an infrared-reflective coating, Chengyi Xu and colleagues created a synthetic device that mimics cephalopod skin. When applying an electrical current, the membrane expands, reflecting more light of a given wavelength. When the electrical current stops flowing through it, the membrane contracts. You can see below how the membrane reacts to electrical stimuli.

Researchers created a squid-shaped version of the device and analyzed its ability to camouflage. Then, they used an infrared camera to measure the changes in the device’s temperature. Scientists report that altering the reflectance of the device so that its temperature changed by a mere 2°Celsius was sufficient to mask its existence from an infrared camera.

Who knows — maybe in the future we could buy octopus skin clothes and activate them when encountering our exes.

Sudden infant death syndrome linked to a rare genetic mutation

A group of researchers discovered a new, important genetic mutation, associated with the breathing muscles, that is implicated in cot deaths. They believe future research will find a way to prevent such tragedies.

Via Pixabay/RitaE

“Previously the whole focus of trying to understand it was either the heart or the brain cells controlling breathing,” said Professor Michael Hanna of the MRC Centre for Neuromuscular Diseases at University College London, one of the authors of the new paper published in The Lancet.

Professor Hanna said that researchers now want to investigate all the other genes associated with the breathing muscles that may be implicated in cot deaths and see what role they are playing.

The newly discovered genetic mutation causes a dysfunction in the management of low oxygen levels in the infant’s blood, researchers said.  It alters the shape of a “sodium pump” that maintains an electric current to stimulate muscle contraction.

“I think the evidence is pretty compelling that some cases of SIDS are caused by sodium channel mutations,” said Prof. Hanna.
“There must be a vulnerability, and what we’re saying is that in some cases, the sodium channel is rendering them vulnerable,” he explained.

Sudden infant death syndrome (SIDS), is also known as crib death because the seemingly healthy infants often die in their cribs during sleep. The affected babies are less than a year old. These tragic events are rare, about 300 such unexpected deaths happening in the UK every year and 2,400 in the US.

Doctors recommend to lay the babies on their back and not their front, not to smoke near them and not to share a bed with them. Time has proven that these measures reduce the risks of cot deaths, but scientists have never understood why such horrible events happened. Previous research has described one other genetic mutation in a heart gene which may play a part in SIDS.

In this new paper, researchers studied the cases of 278 children who died unexpectedly and were diagnosed with SIDS – 84 from the UK and 194 from the US. After sequencing their genome, scientists compared them with the ones of adults with no cardiovascular, neurological or respiratory diseases.

Next, researchers looked at the prevalence of the SCN4A gene that codes for a cell surface receptor found on top of breathing muscular cells. At birth, the expression of this surface receptor is low, gradually increasing during the first two years of life.

Scientists observed that the rare mutation was found in four of the children previously diagnosed with SIDS, and in none of the adults. Even though the figure may not seem relevant to you, researchers say it is highly significant because it is normally found in fewer than five people in every 100,000. The research team believes that this mutation could affect children’s breathing muscles, making them weaker. Infants are most vulnerable when sleeping in the wrong position or tangled in the bedclothes.

“In the population we studied, the evidence is strong that it is at the very least a risk factor in those cases that had it [the genetic mutation],” said Hanna. “It certainly doesn’t explain the majority of Sids,” he concluded.

Luckily, in the future, researchers will be able to find all the genes implicated in triggering SIDS and develop a method to fight this dreadful syndrome.

Meet your new organ: the interstitium

Doctors have identified a previously unknown feature of human anatomy with many implications for the functions of most organs and tissues, and for the mechanisms of most major diseases.

Structural evaluation of the interstitial space. (A) Transmission electron microscopy shows collagen bundles (asterisks) that are composed of well-organized collagen fibrils. Some collagen bundles have a single flat cell along one side (arrowheads). Scale bar, 1 μm. (B) Higher magnification shows that cells (arrowhead) lack features of endothelium or other types of cells and have no basement membrane. Scale bar, 1 μm. (C) Second harmonics generation imaging shows that the bundles are fibrillar collagen (dark blue). Cyan-colored fibers are from autofluorescence and are likely elastin, as shown by similar autofluorescence in the elastic lamina of a nearby artery (inset) (40×). (D) Elastic van Gieson stain shows elastin fibers (black) running along collagen bundles (pink) (40×).

A new paper published on March 27th in Scientific Reports, shows that layers of the body long thought to be dense, connective tissues — below the skin’s surface, lining the digestive tract, lungs, and urinary systems, and surrounding arteries, veins, and the fascia between muscles — are instead interconnected, fluid-filled spaces.

Scientists named this layer the interstitium — a network of strong (collagen) and flexible (elastin) connective tissue fibers filled with fluids, that acts like a shock absorber to keep tissues from rupturing while organs, muscles, and vessels constantly pump and squeeze throughout the day.

This fluid layer that surrounds most organs may explain why cancer spreads so easily. Scientists think this fluid is the source of lymph, the highway of the immune system.

In addition, cells that reside in the interstitium and collagen bundles they line, change with age and may contribute to the wrinkling of skin, the stiffening of limbs, and the progression of fibrotic, sclerotic and inflammatory diseases.

Scientists have long known that more than half the fluid in the body resides within cells, and about a seventh inside the heart, blood vessels, lymph nodes, and lymph vessels. The remaining fluid is “interstitial,” and the current paper is the first to define the interstitium as an organ in its own right and, the authors write, one of the largest of the body, the authors write.

A team of pathologists from NYU School of Medicine thinks that no one saw these spaces before because of the medical field’s dependence on the examination of fixed tissue on microscope slides. Doctors examine the tissue after treating it with chemicals, slicing it thinly, and dyeing it in various colorations. The “fixing” process allows doctors to observe vivid details of cells and structures but drains away all fluid. The team found that the removal of fluid as slides are made makes the connective protein meshwork surrounding once fluid-filled compartments to collapse and appear denser.

“This fixation artifact of collapse has made a fluid-filled tissue type throughout the body appear solid in biopsy slides for decades, and our results correct for this to expand the anatomy of most tissues,” says co-senior author Neil Theise, MD, professor in the Department of Pathology at NYU Langone Health. “This finding has potential to drive dramatic advances in medicine, including the possibility that the direct sampling of interstitial fluid may become a powerful diagnostic tool.”

Researchers discovered the interstitium by using a novel medical technology — Probe-based confocal laser endomicroscopy. This new technology combines the benefits of endoscopy with the ones of lasers. The laser lights up the tissues, sensors analyze the reflected fluorescent patterns, offering a microscopic real-time view of the living tissues.

When probing a patient’s bile duct for cancer spread, endoscopists and study co-authors Dr. David Carr-Locke and Dr. Petros Benias observed something peculiar — a series of interconnected spaces in the submucosa level that was never described in the medical literature.

Baffled by their findings, they asked Dr. Neil Theise, professor in the Department of Pathology at NYU Langone Health and co-author of the paper for help in resolving the mystery. When Theise made biopsy slides out of the same tissue, the reticular pattern found by endomicroscopy vanished. The pathology team would later discover that the spaces seen in biopsy slides, traditionally dismissed as tears in the tissue, were instead the remnants of collapsed, previously fluid-filled, compartments.

Researchers collected tissues samples of bile ducts from 12 cancer patients during surgery. Before the pancreas and the bile duct were removed, patients underwent confocal microscopy for live tissue imaging. After recognizing this new space in images of bile ducts, the team was able to quickly spot it throughout the body.

Theise believes that the protein bundles seen in the space are likely to generate electrical current as they bend with the movements of organs and muscles, and may play a role in techniques like acupuncture.

Another scientist involved in the study was first author Rebecca Wells of the Perelman School of Medicine at the University of Pennsylvania, who determined that the skeleton in the newfound structure was comprised of collagen and elastin bundles.

Pot twist: Cannabis component helps fight addiction in new study

A new study published in the journal Neuropsychopharmacology has revealed that a non-psychoactive and non-addictive ingredient of the Cannabis sativa plant can help reduce the risk of relapse among cocaine and alcohol addicts. According to lead author Friedbert Weiss, non-psychoactive cannabinoids could have important medical benefits in the fight against substance addiction.

Image via Pixabay/futurefilmworks

Addiction is a powerful, vicious monster that lives inside yourself. The battle is an extremely hard one and it often carries stretches out over years and years — potentially for an entire life. Many abstinent addicts find it even harder to control themselves in drug-related settings or when they experience stress or higher levels of anxiousness. For them, it’s a true struggle to dismiss their impulses when offered an addictive drug like alcohol or cocaine.

Researchers wanted to study the effect of Cannabidiol (CBD) on drug relapse in a rat model. CBD is a non-psychoactive compound of the plant Cannabis sativa (I suppose you already know that’s weed). CBD has been considered as a treatment for neurological and psychiatric disorders, and more recently also as a treatment for drug and alcohol addiction.

“The efficacy of the cannabinoid [CBD] to reduce reinstatement in rats with both alcohol and cocaine – and, as previously reported, heroin – histories predicts therapeutic potential for addiction treatment across several classes of abused drugs,” says Weiss.

Scientists applied a gel containing CBD once per day for a week to the skin of lab rats. The rodents had a history of deliberate daily alcohol or cocaine self-administration, leading to addiction-like behavior.

Next, they performed a number of tests to observe the rats’ reaction to stressful and anxiety-provoking situations, as well as behavior tests that measured impulsivity — a psychological trait associated with drug addiction. The research team reported that CBD reduced relapse provoked by stress and drug cues. CBD also reduced anxiety and impulsivity in the rats.

The authors wrote: “CBD attenuated context-induced and stress-induced drug seeking without tolerance, sedative effects, or interference with normal motivated behavior. Following treatment termination, reinstatement remained attenuated up to ≈5 months although plasma and brain CBD levels remained detectable only for 3 days. CBD also reduced experimental anxiety and prevented the development of high impulsivity in rats with an alcohol dependence history.”

Authors hope that insight into the mechanisms by which CBD exerts these effects will be investigated in future research. They believe that the findings are proof of CBD’s potential in relapse prevention, CBD’s major benefits being its actions across several vulnerability states, and long-lasting effects with only brief treatment.

“Drug addicts enter relapse vulnerability states for multiple reasons. Therefore, effects such as these observed with CBD that concurrently ameliorate several of these are likely to be more effective in preventing relapse than treatments targeting only a single state,” Weiss concludes.

Cutting calories delays ageing, new study shows

A new comprehensive study has shown that reducing caloric intake slows down metabolism. Researchers believe the findings indicate that a low-calorie diet could extend lifespan and prolong health in old age.

Via Pixabay/Divily

Previous studies on animals with short lifespans — such as worms, mice, and flies — have shown that reducing calorie intake might slow down metabolism and prolong life. However, demonstrating this effect on humans and other animals with long lifespans has proven quite difficult.

Researchers studied some of the people who participated in the multi-center trial CALERIE (Comprehensive Assessment of Long-term Effects of Reducing Intake of Energy), sponsored by the US National Institutes of Health. Scientists observed the effects of restricting calories for 2 years on metabolism in over 200 healthy, non-fat adult participants.

“The CALERIE trial has been important in addressing the question of whether the pace of aging can be altered in humans,” says Rozalyn Anderson, who studies aging at the University of Wisconsin–Madison. She leads one of two large, independent studies on calorie restriction in rhesus monkeys. “This new report provides the most robust evidence to date that everything we have learnt in other animals can be applied to ourselves.”

The latest paper, which was published on March 22nd in the journal Cell Metabolism, monitored 53 CALERIE participants recruited at the Pennington Biomedical Research Center in Baton Rouge, Louisiana. Researchers were able to track how the participants used energy with unprecedented precision thanks to state-of-the-art metabolic chambers —  small, hotel-like sealed rooms that measure oxygen and carbon dioxide concentrations every 60 seconds. Researchers calculated the ratio between the two gases and then analyzed occupants’ urinary nitrogen, indicating whether the occupant is burning fat, carbohydrate or protein.

Participants, with ages between 21 and 50, were randomly separated into two groups: the 34 people in the experimental group reduced their calorie consumption by an average of 15%, while the 19 people in the control group ate as usual. Next, researchers tested the participants annually to record overall metabolism and biological markers of aging, including damage associated with oxygen free radicals released during metabolism. At the end of the trial, participants spent 24 hours in the metabolic chamber.

Researchers discovered that the people who had dieted used energy much more efficiently while sleeping than the control group. Their base metabolism had essentially slowed down. In consequence, people in the experimental group lost an average of 9 kilos individually. All other measurements showed a reduced metabolic rate and fewer signs of aging.

“The Rolls-Royce of a human longevity study would carry on for many decades to see if people do actually live longer,” says Pennington physiologist Leanne Redman, the lead author of the latest study.

Low-calorie diets have previously been shown to extend life in different species, such as the short lifespan worm Caenorhabditis elegans, and in the fly Drosophila melanogaster. Following studies also revealed that mice with restricted diets can live up to 65% longer than mice allowed to eat freely. In addition, studies on monkeys suggest longer survival and reduced signs of aging.

Redman wants to repeat the study combining moderate calorie restriction with a diet rich in antioxidants to monitor oxidative stress, or with a drug such as resveratrol, which mimics key aspects of calorie restriction.

If researchers demonstrate the causality between caloric reduction and longer lives in humans, could you stick to such a diet?

Scientists discover why cockroaches are such good survivors

Researchers sequenced the American cockroach‘s genome for the first time, discovering what makes them such great survivors.

Periplaneta americana Via Flickr

The American cockroach, also known as Periplaneta americana, possesses widely expanded gene families related to taste and smell, detoxification and immunity, compared with other insects, found a team of researchers who published their discovery on March 20 in the journal Nature Communications.

“It makes total sense in the context of the lifestyle,” said Coby Schal, an entomologist at North Carolina State University who was part of a team that last month reported an analysis of the genome of the German cockroach (Blattella germanica). “Many of the gene families that expanded in the American cockroach were also expanded in the German cockroach”, Schal said.

That actually makes sense because both species are omnivorous scavengers that can thrive on altered food in extremely unsanitary environments — at least by human standards.

The American cockroach originally comes from Africa but was introduced to the Americas in the 1500s. Unlike the German cockroach, which is found almost exclusively in human dwellings, the American cockroach only tends to venture into the basements or bottom levels of buildings, according to Schal.

In China, the cockroach is often called “xiao qiang,” meaning “little mighty,” according to Sheng Li, an entomology professor at South China Normal University in Guangzhou and lead author of the paper. “It’s a tiny pest, but has very strong vitality,” he said.

The two species are remarkable survivors and their mysterious abilities appear to lie within their genes. In the new paper, professor Sheng Li and his team found that American cockroaches have the second-largest genome of any insect ever sequenced, right behind the migratory locust (Locusta migratoria). Curiously enough, 60% of the insect’s genome consists of repetitive segments. Gene families related to taste and smell were much larger than those of other bugs, and scientists counted 522 taste receptors in the roach. German cockroaches possess a similar number of taste receptors (545), Schal said.

“They need very elaborate smell and taste systems in order to avoid eating toxic stuff,” Schal added.

Source: Flickr

Interestingly, American cockroaches also have large gene families responsible for metabolization of toxic substances, including some chemicals found in insecticides — their ‘cousins’, the German cockroaches have them too. Schal said that both roaches evolved this way long before humans ruled the world. Resistance to toxic substances developed in roaches thanks to the abundance of toxin-producing bacteria in their environments and their tendency to eat rotten plant matter, he explained.

In addition, the American cockroach has a large number of immunity genes, perhaps another adaptation to unsanitary environments and fermenting food sources, Li and colleagues wrote.

Finally, the team discovered that the insect had a large number of genes devoted to physical development, such as genes responsible for synthesizing the insect’s juvenile hormone or the proteins in its exoskeleton. Authors were not surprised by this since American cockroaches can measure up to 2 inches (53 millimeters) long.

A greater understanding of the cockroach genome could help researchers come up with new ways to control theses pest species. One interesting research interest, Schal said, is the Asian cockroach (Blattella asahinai), a close relative of the pesky German cockroach that lives outdoors and doesn’t really bother humans. It would be interesting to see what are the differences between the Asian and German cockroach genomes.

Still, there’s a long way to go before we can see the broad picture of cockroach genetics.

“There are 5,000 described species of cockroaches, and now we have two [full] genomes,” Schal concluded. “So we need more.”

Hip hop music teaches children to recognize stroke and act quickly, study finds

Researchers have discovered that a musical movement that uses hip-hop music to educate economically-disadvantaged minority children and their parents about strokes has shown promising results in helping the increase of stroke awareness.

Via YouTube

“The lack of stroke recognition, especially among blacks, results in dangerous delays in treatment,” said Olajide Williams, M.D., M.S., study author and associate professor of neurology at Columbia University Medical Center, New York Presbyterian Hospital. “Because of those delays, only a quarter of all stroke patients arrive at the hospital within the ideal time for clot-busting treatment.”

A simple 9-1-1 call can save someone’s life. Calling an ambulance immediately when stroke symptoms start could increase the rate of optimal stroke treatment by 24%. It is very important for people to start recognizing the symptoms and know what to do in this kind of situation. Strokes kill four times more 35- to 54-year-old black Americans than white Americans.

Sadly, a lot of stroke awareness campaigns have been limited by the high costs of advertising, lack of cultural tailoring and low penetration into ethnic minority populations. But not all of them — “Hip Hop Stroke”, a three-hour multimedia stroke awareness intervention that teaches children rap songs about strokes, has shown great success in stroke education.

Scientists studying more than 3,000 4th through 6th graders from 22 public schools in New York City and a group of 1,144 of their parents have discovered that this campaign increased optimal stroke knowledge from 2% of children before the intervention to 57% right after. Another encouraging finding was that three months after the campaign had ended, 24% of children remembered all they had learned.

“Hip Hop Stroke” uses original hip-hop songs, comic books, and cartoon-style videos to make the kids remember facts about strokes. One of the invented acronyms of the project was F-A-S-T, which refers to stroke warning signs: Face dropping, Arm weakness, Speech difficulty, Time to call 9-1-1. Famous rapper Doug E. Fresh lent a hand in the artistic process and composed music and lyrics for the campaign.

“Rhymes have been shown to have quantifiable educational value,” said Dr. Williams.

Parents also learned new things. Pre-intervention, only 3% of the adults could identify stroke symptoms. That figure rose to 20% after they watched the educational videos. Three months later, 17% retained the information.

Dr. Williams, also known as the Hip Hop Doc, said that time is of the essence when it comes to stroke and clot-busting treatment.

“Every minute a stroke continues 1.9 million brain cells die. The earlier the treatment, the better the outcome,” he declared.

Williams has been conducting this study for over the past five years. He is delighted by the results and hopes that the free program will soon be used around the country.

“The program’s culturally-tailored multimedia presentation is particularly effective among minority youth or other groups among whom Hip Hop music is popular,” Williams said. “One unique aspect of the program is that the children who receive the program in school are used as ‘transmission vectors’ of stroke information to their parents and grandparents at home. Our trial showed that this is an effective strategy.”

https://www.youtube.com/watch?v=OlxWsWu9Y-Q

The paper was published in the American Heart Association Journal Stroke.

Doctors restore patient’s sight with stem cells, offering new hope for cure to blindness

Scientists have developed a specially engineered retinal patch to treat people with sudden, severe sight loss.

The macula lutea (an oval region at the center of the retina) is responsible for the central, high-resolution color vision that is possible in good light; when this kind of vision is impaired due to damage to the macula, the condition is called age-related macular degeneration (AMD or ARMD). Macula lutea means ‘yellow spot’ in Latin.

Picture of the back of the eye showing intermediate age-related macular degeneration.
Via Wikipedia

Douglas Waters, an 86-year-old from London, had lost his vision in July 2015 due to severe AMD. After a few months, Waters became part of a clinical trial developed by UC Santa Barbara researchers that used stem cell-derived ocular cells. He received his retinal implant at Moorfields Eye Hospital, a National Health Service (NHS) facility in London, England.

Before the surgery, Water’s sight was very poor, and he wasn’t able to see anything with his right eye. After the surgery, his vision improved so much that he could read the newspaper and help his wife in the garden.

The study, published in Nature Biotechnology, shows groundbreaking results. Researchers could safely and effective implant a specially engineered patch of retinal pigment epithelium cells derived from stem cells to treat people with sudden severe sight loss from wet AMD. This is the first time a completely engineered tissue has been successfully transplanted in this manner.

“This study represents real progress in regenerative medicine and opens the door on new treatment options for people with age-related macular degeneration,” said co-author Peter Coffey, a professor at UCSB’s Neuroscience Research Institute and co-director of the campus’s Center for Stem Cell Biology & Engineering.

Douglas Waters was struggling to see up close after developing severe macular degeneration, but 12 months on he is able to read a newspaper again

AMD usually affects people over the age of 50 and accounts for almost 50% of all visual impairment in the developed world. The condition disturbs central vision responsible for reading, leaving the surrounding eyesight normal. Wet AMD is caused by hemorrhage or liquid accumulation into the region of the macula, in the center of the retina. Wet AMD almost always starts as dry AMD. Researchers believe that this new technique will be the future cure for dry AMD.

Scientists wanted to see whether the diseased retinal cells could be replenished using the stem cell patch. They used a specially engineered surgical tool to insert the patch under the affected retina. The operation lasted almost two hours.

Besides Water, another patient, a 60-year-old woman who also suffered from wet AMD, underwent the surgery. The two patients were observed for one year and reported improvements to their vision. The results were incredible — the patients went from being almost blind to reading 60 to 80 words per minute with normal reading glasses.

“We hope this will lead to an affordable ‘off-the-shelf’ therapy that could be made available to NHS patients within the next five years,” said Coffey, who founded the London Project to Cure Blindness more than a decade ago.

 

 

Male contraceptive pill passes first safety test

Oral birth control for men might not be such a futuristic idea. Researchers have just finished the first human study on the experimental male oral contraceptive—called dimethandrolone undecanoate, or DMAU. They concluded that taking DMAU daily for a month is safe and does not lower libido or alter fertility permanently.

Via Vimeo/Lee Health

This pill is very similar to the one women use — it combines two hormones at the same time, an androgen (male hormone) like testosterone, and progestin.

To test DMAU’s safety, researchers developed a double-blind randomized, dose escalation, placebo-controlled study. Stephanie Page, MD, of the University of Washington in Seattle, and her colleagues observed that testosterone levels among patients who had received the highest dose of DMAU dropped to levels seen in medical castration for prostate cancer.

Even though testosterone levels dropped dramatically in the 28-day experiment, no symptoms of low testosterone emerged, increasing DMAU’s chances of becoming an oral male contraceptive according to Dr. Paige at ENDO 2018.

“These results are a big step forward in the development of a male pill,” she told MedPage Today. “We are very encouraged by the results of this safety trial.”

Participants ingested doses of 100 mg, 200 mg, and 400 mg of dimethandrolone in two delivery formulations — with castor oil or in a capsule. For each dose, there were 12-15 men and five placebo patients so that researchers could compare adverse effects. Participants took the pill with high-fat meals. Overall, 100 men between the ages 18 and 50 were enrolled in the trial and 82 completed all parts of the study.

“The men experienced no hot flashes and no mood changes, and no problems with sexual function compared with the placebo group,” Paige said. “There was no evidence of liver toxicity. We did see mild weight gain and an increase in cholesterol levels and that may require us to fine tune the dosing, but overall we are very encouraged about the safety profile of dimethandrolone.”

Dr. Page said her group will begin a 3-month study in April to see if any long-term toxicity appears, and then will do a study in couples to determine if DMAU does efficiently work as birth control. She added the current trial was to determine if the pill could be taken safely for more than one dose, but did not test its effectiveness as a contraceptive. Participants were told to use auxiliary contraception if the had sex while on the pill.

“Condoms are the only practical reversible form of male contraception — and it is more than 300-years-old,” she noted. She said that studies indicate that men would prefer oral contraception versus injection or gel implant.

Page explained that previous attempts to drive down testosterone levels to reduce sperm production led to side effects and liver toxicity. She added that an effective oral contraceptive for men was hard to produce until now, due to the rapid metabolization rates of androgenous hormones by the male body.

“Dimethandrolone is a modified form of testosterone, which has been chemically modified to get rid of the problem of liver toxicity,” she explained. “A long fatty acid chain has been added to another portion of the molecule to increase its absorption in the blood stream, so we can get around the twice-a-day dosing. Dimethandrolone is different than testosterone in that it binds to both the progesterone receptor and the androgen receptor so we don’t need two different steroids in order to have an effective male contraceptive,” Paige added.

A month after the treatment had stopped, testosterone levels returned to normal, Dr. Paige reported.

“This shows reversibility, the key feature of a hormonal contraceptive. This was much more potent than we had expected with just once-day dosing. Despite these incredibly low levels of testosterone, the men did not have symptoms of low testosterone. Because dimethandrolone is a modified form of testosterone, when we give the right dose of dimethandrolone, all those important secondary sexual characteristic in the man will be maintained in the body,” she added.

Until now, DMAU shows promising results. But for the trial to be complete, we need to see long-term effects and sperm count. Maybe the study that begins in April will present us encouraging findings as well as the one presented at ENDO 2018, the Endocrine Society’s 100th annual meeting in Chicago, on Sunday.

Researchers develop nanospears that can transport DNA to cells with pinpoint accuracy

Researchers have recently developed remote-controlled, needle-like nanospears capable of piercing membrane walls and delivering DNA into selected cells. This new technology allows biological materials to be transported throughout the body with pinpoint accuracy, thus making gene alteration a simpler and more effective procedure.

Genetically modified cells are now used in stem cell and cancer research, but the production of such cells is rather costly and inefficient, often including viruses, harsh chemical reagents or external electrical fields.

In the past, researchers used sharp-tipped nanoparticles stuck to surfaces in order to deliver molecules to cells, but removing the altered cells from the nanoparticle-coated surface was difficult. Other techniques involved self-propelled nanoparticles, but controlling them was not easy. In addition, mobile nanoparticles can generate toxic byproducts.

A team of scientists from the University of California, Los Angeles, wanted to make the process more efficient, so they developed biocompatible nanospears that can accurately transport biological material via an external magnetic field. In this way, cells are safe from damage and the use of chemical propellants is no longer necessary.

Authors Steven J. Jonas, Paul S. Weiss, Xiaobin Xu and colleagues fabricated nanospears using templates made of polystyrene beads. They put the beads on a silicon structure and etched them down into a sharp spear shape. After the beads’ removal, they coated the resulting silicon spears with thin layers of nickel and functionalized gold, so that biomolecules, such as DNA, could attach.

Next, the team scraped the nanospears from the silicon. Thanks to the magnetic nickel layer, scientists could accurately control the particles’ movements and orientation. Then, researchers tested their invention in a lab dish, where the nanospears had to deliver DNA to brain cancer cells. The cancerous cells were altered so that they would express a green fluorescent protein.

Researchers were pleased with the results: more than 90% of the cells remained viable, and more than 80% exhibited green fluorescence. The results also showed that this method was less harmful and more effective than other non-viral ones. The authors believe that this technique might lead to new ways to prepare vast numbers of cells for the coordinated manufacture of gene therapies.

The paper was published today in the journal ACS Nano.

Lead exposure might be responsible for 10 times more premature deaths than previously thought

A new study suggests that lead exposure may be responsible for nearly 10 times more deaths in the United States than previously thought.

Credit: Wikipedia.

Scientists have discovered that nearly 412,000 deaths each year in the US can be attributed to lead contamination. That number is ten times higher than the Institute for Health Metrics and Evaluation at the University of Washington in Seattle had previously reported.

“Today, lead exposure is much lower because of regulations banning the use of lead in petrol, paints and other consumer products, so the number of deaths from lead exposure will be lower in younger generations. Still, lead represents a leading cause of disease and death, and it is important to continue our efforts to reduce environmental lead exposure,” explained Professor Bruce Lanphear, from Simon Fraser University in Canada.

Lanphear and colleagues estimated that 28.7% of heart disease-related premature deaths in the US could be caused by lead exposure, which comes to a total of 256,000 deaths annually. 

Researchers used data from the Third National Health and Nutrition Examination Survey, which monitored 14,289 US adults for 20 years. Of the 4,422 participants who died by 2011, approximately 18% of them could have been saved by reducing blood lead concentrations to 1.0 micrograms per deciliter.

Compared to those with low lead blood concentrations, people with high lead levels (over 6.7 micrograms) had the risk of premature death from any cause increased by 37%, the risk of cardiovascular death increased by 70%, and double the risk of death from ischemic heart disease.

“Our study calls into question the assumption that specific toxicants, like lead, have ‘safe levels’, and suggests that low-level environmental lead exposure is a leading risk factor for premature death in the USA, particularly from cardiovascular disease,” Professor Lanphear said in a statement.

Lead exposure can contribute to cardiovascular disease by various pathways. Lead affects the epithelial cells of the blood vessels, which increases the chances of developing plaques that can then cause a heart attack. Lead contamination also leads to kidney damage, which causes high blood pressure and probably acts synergistically with plaque formation.
Also, if you live near an airport, your blood lead levels will be a little higher than if you live farther away due to the lead found in the aviation gas used in single piston jets.

“Estimating the contribution of low-level lead exposure is essential to understanding trends in cardiovascular disease mortality and developing comprehensive strategies to prevent cardiovascular disease. Currently, low levels of lead exposure are an important, but largely ignored risk factor for deaths from cardiovascular disease,” said Professor Lanphear.

The team admits that the study’s principal limitation is that the research relied heavily on one blood concentration measurement taken at the beginning of the study period, almost 20 years ago.
“Our reliance on a single blood test as opposed to serial blood tests means that we have underestimated the impact of lead exposure on cardiovascular disease,” Lanphear said. “There are some things in the study design itself that we really couldn’t change.”

The team urges the retirement of lead-contaminated housing, lead-laden jet fuels, lead water pipes, and the reduction of emissions from smelters and lead battery facilities.

“We’ve made tremendous progress in reducing these exposures in the past four to five decades,” Lanphear added. “But our blood levels are still 10 to 100 times higher than our pre-industrial ancestors,” Lanphear concludes.

Scientific reference: Bruce Lanphear , Stephen Rauch, Peggy Auinger, Ryan W Allen , Richard W Hornung. Low-level lead exposure and mortality in US adults: a population-based cohort studyThe Lancet Public Health, 2018 DOI: 10.1016/S2468-2667(18)30025-2

Neanderthals were compassionate caregivers, researchers suggest

Homo neanderthalensis, adult male. Reconstruction based on Shanidar 1 by John Gurche

Neanderthals are seen as brutish and uncaring, but a new archeological study has shown that Neanderthals benefited from an effective and knowledgeable healthcare system.

Researchers from the University of York revealed that Neanderthal healthcare was uncalculated and highly effective, even though we tend to think of about them as crueler than modern-day humans. The study suggests that Neanderthals were very compassionate caregivers.

The scientific community knows very well that Neanderthals sometimes provided care for the injured, but the team at York re-analyzed Neanderthal behavior and they suggest ‘our cousins’ were genuinely caring of their peers regardless of the level of illness or injury, rather than helping others out of self-interest.

Lead author, Dr. Penny Spikins, senior lecturer in the Archaeology of Human Origin at the University of York, said, “Our findings suggest Neanderthals didn’t think in terms of whether others might repay their efforts, they just responded to their feelings about seeing their loved ones suffering.”

The individuals researchers know about had a severe injury or disease, with detailed pathologies highlighting a range of debilitating conditions and injuries. Sometimes, the injuries occurred long before the time of death and would have required monitoring, massage, fever management and hygiene care, researchers suggest.

Researchers analyzed a male around 25-40 years old at time of death that showed a catalog of poor health, including a degenerative disease of the spine and shoulders. His degrading physical state would have sapped his strength over the final 12 months of life and severely restricted his ability to contribute to the community. The authors of the study believe he remained part of the group since his articulated remains were subsequently carefully buried.

Dr Spikins added, “We argue that the social significance of the broader pattern of healthcare has been overlooked and interpretations of a limited or calculated response to healthcare have been influenced by preconceptions of Neanderthals as being ‘different’ and even brutish. However, a detailed consideration of the evidence in its social and cultural context reveals a different picture.

“The very similarity of Neanderthal healthcare to that of later periods has important implications. We argue that organised, knowledgeable and caring healthcare is not unique to our species but rather has a long evolutionary history.”

The paper was published in the journal World Archaeology.

Poor sleep linked to increased risk of Alzheimer’s disease

Researchers have discovered that daytime sleepiness might cause brain build-ups leading to Alzheimer’s disease (AD).

Via Pixabay/gracic

Elderly people feeling drowsy during the day due to poor sleep or waking up in the night had a greater build-up in their brain of amyloid plaques which consume the brain, kill cells, and eventually lead to total memory loss. And this makes sense: recent studies have shown that while the brain sleeps, it clears away deposits of amyloid.

Even though previous research showed a correlation between sleepiness and AD, scientists wondered if the accumulation of amyloid plaques in the patients’ brains caused sleep problems or if it was the other way around.

Now, a team led by Mayo Clinic’s Prashanthi Vemuri has cast light on the subject: sleep itself seems to be causing the plaque accumulation that triggers the neurodegenerative disease.

“This study is the first in humans to demonstrate a predictive association between a measure of sleep disturbance at baseline and change in an AD [Alzheimer’s disease] biomarker across multiple points,” Joseph R. Winer and Bryce A. Mander, of the University of California, wrote in an editorial published with the study in the Journal of the American Medical Association.

The research team studied 283 people aged 70 or older without dementia from the center’s Study of Aging. Each participant completed surveys that assessed their general sleepiness and had at least two consecutive imaging scans of their brains from 2009 to 2016. The scans monitored the difference in amyloid plaque quantity between two scans in different regions of the brain.

Researchers discovered that 63 participants (22.3%) had excessive daytime sleepiness, and this was associated with increased amyloid plaque accumulation in susceptible regions of the brain.

“We found that daytime sleepiness was causing more deposition of amyloid in people who are already amyloid positive, so it was influencing the rate of deposition over time,” Dr. Vermuri said.

Although the study seems to establish causation between sleep patterns and amyloid accumulation, the team still has no definitive answer to why and how sleep has this effect.

However, experts consider this study a breakthrough, believing the findings underline the importance of good sleep for preserving brain health.

“This study and others present evidence that poor sleep quality may be an early warning sign of AD-related processes,” Winer and Mander wrote. “Although a better understanding of the role of sleep in the AD cascade could soon lead to effective sleep-based therapies, at present, maintaining healthy sleep and treating clinical sleep disorders must be a current priority for mental health in older adults.:

Scientists invent phone app that accurately monitors blood pressure

Researchers developed new hardware and a smartphone app that can measure blood pressure (BP) as accurately as existing cuff devices.

Via Pixabay/rawpixel

The team of scientists from Michigan State University (MSU) also found a new, more convenient, measurement point. Stanard measurement devices use the brachial artery as the conventional measurement point, but the team discovered that measuring BP on fingertip arteries was very easy and exact.

“We targeted a different artery, the transverse palmer arch artery at the fingertip, to give us better control of the measurement,” said Anand Chandrasekhar, PhD student at MSU. “We were excited when we validated this location. Being able to use your fingertip makes our approach much easier and more accessible,” said Chandrasekhar, lead author of the study published in the journal Science Translational Medicine.

How does the app work?

The app uses two sensors: one is optical, and one is force. The optical sensor lies on top of the force sensor in a compact unit housed in a one centimeter-thick case attached to the back of the phone. Users turn on the app and press their fingertip against the sensor unit. With their finger on the unit, they keep the phone at heart level and watch the screen to ensure they are applying the correct amount of finger pressure.

“A key point was to see if users could properly apply the finger pressure over time, which lasts as long as an arm-cuff measurement,” said Ramakrishna Mukkamala, professor at MSU. “We were pleased to see that 90% of the people trying it were able to do it easily after just one or two practice tries.”

According to the WHO, raised blood pressure is estimated to cause 7.5 million deaths per year worldwide, about 12.8% of the total of all deaths. High blood pressure is a major risk factor for coronary heart disease and strokes. In addition, complications of raised blood pressure include heart failure, peripheral vascular disease, renal impairment, retinal hemorrhage and visual impairment. Treating systolic blood pressure and diastolic blood pressure until they are less than 140/90 mmHg is associated with a reduction in cardiovascular complications.

The treatment usually requires both lifestyle changes and medication, and only 20 percent of people with hypertension have their condition under control. This new phone app gives patients an advantageous alternative — keeping a log of day by day estimations would deliver an exact BP average, with periodical estimation becoming obsolete, believes Mukkamala. In this way, medication dosage will be better adjusted to each individual.

I think this is great news for all of us. I remember thinking that the incorporated sensor that measures pulse and oxygen saturation found on the back of some smartphones might need new medical updates, including blood pressure measurement. Luckily, this day has come, and the future just became brighter.

Air pollution exposure during fetal life linked to brain abnormalities in children

A new study suggests that unborn babies exposed to ‘safe’ levels of air pollution are prone to developing brain abnormalities that might contribute to cognitive impairment later in life.

Via Flickr/wissenschaftsjahr

Scientists from the Netherlands have observed that exposure to fine particles during fetal development is linked to a thinner cortex — the exterior layer of the brain that regulates self-control over impulsive behavior. Such cognitive impairment at early ages could have significant long-term consequences.

“We observed brain development effects in relationship to fine particles levels below the current EU limit,” lead author Dr. Mònica Guxens, of the Barcelona Institute for Global Health (ISGlobal), Spain, a center supported by the “la Caixa” Foundation, and Erasmus University Medical Center, the Netherlands, said in a statement.

Other recent studies have associated acceptable air pollution levels with other complications such as cognitive decline and fetal growth development.

The team of researchers used a population-based cohort in the Netherlands, which observed pregnant women and their children from fetal life onward. The researchers assessed the levels of home air pollution during the fetal life of 783 children and collected data by air pollution monitoring campaigns, measuring levels of nitrogen dioxide, coarse particles, and fine particles.

Scientists also scanned the brains of children between the ages of six and ten and discovered abnormalities in the thickness of the brain cortex, the precuneus and rostral middle frontal region. That’s despite the fact that the levels of fine particles and nitrogen dioxide measured in their homes were acceptable by EU standards.

“Air pollution is so obviously bad for lungs, heart, and other organs that most of us have never considered its effects on the developing brain,” Dr. John Krystal, editor of Biological Psychiatry, said in a statement. “But perhaps we should have learned from studies of maternal smoking that inhaling toxins may have lasting effects on cognitive development.”

The paper suggests that the fetal brain is very vulnerable during pregnancy because it hasn’t yet developed the mechanisms for removal of, or protection against, environmental toxins.

“Although specific individual clinical implications of these findings cannot be quantified, based on other studies, the observed cognitive delays at early ages could have significant long-term consequences such as increased risk of mental health disorders and low academic achievement, in particular due to the ubiquity of the exposure,” Guxens added.

The study was published in Biological Psychiatry.

We can’t grow new neurons in adulthood after all, new study says

Previous research has suggested neurogenesis — the birth of new neurons — was able to take place in the adult human brain, but a new controversial study published in the journal Nature seems to challenge this idea.

a. Toluidine-blue-counterstained semi-thin sections of the human Granule Cell Layer (GCL) from fetal to adult ages. Note that a discrete cellular layer does not form next to the GCL and the small dark cells characteristic of neural precursors are not present.

Scientists have been struggling to settle the matter of human neurogenesis for quite some time. The first study to challenge the old theory that humans did not have the ability to grow new neurons after birth was published in 1998, but scientists had been questioning this entrenched idea since the 60’s when emerging techniques for labeling dividing cells revealed the birth of new neurons in rats. Another neurogenesis study was published in 2013, reinforcing the validity of the results from 1998.

Arturo Alvarez-Buylla, a neuroscientist at the University of California, San Francisco, and his team conducted a study to test the neurogenesis theory using immunohistochemistry — a process that applies various fluorescent antibodies on brain samples. The antibodies signal if young neurons as well as dividing cells are present. Researchers involved in this study were shocked by the findings.

“We went into the hippocampus expecting to see many young neurons,” says senior author Arturo Alvarez-Buylla. “We were surprised when we couldn’t find them.”

In the new study, scientists analyzed brain samples from 59 patients of various ages, ranging from fetal stages to the age of 77. The brain tissue samples came from people who had died or pieces were extracted in an unrelated procedure during brain surgery. Scientists found new neurons forming in prenatal and neonatal samples, but they did not find any sustainable evidence of neurogenesis happening in humans older than 13. The research also indicates the rate of neurogenesis drops 23 times between the ages one and seven.

But some other uninvolved scientists say that the study left much room for error. The way the brain slices were handled, the deceased patients’ psychiatric history, or whether they had brain inflammation could all explain why the researchers failed to confirm earlier findings.

The 1998 study was performed on brains of dead cancer patients who had received injections of a chemical called bromodeoxyuridine while they were still alive. The imaging molecule — which was used as a cancer treatment — became integrated into the DNA of actively dividing cells. Fred Gage, a neuroscientist involved in the 1998 study, says that this new paper does not really measure neurogenesis.

“Neurogenesis is a process, not an event. They just took dead tissue and looked at it at that moment in time,” he adds.

Gage also thinks that the authors used overly restrictive criteria for counting neural progenitor cells, thus lowering the chances of seeing them in adult humans.

But some neuroscientists agree with the findings. “I feel vindicated,” Pasko Rakic, a longtime outspoken skeptic of neurogenesis in human adults, told Scientific American. He believes the lack of new neurons in adult primates and humans helps preserve complex neural circuits. If new neurons would be constantly born throughout adulthood, they could interfere with preexisting precious circuits, causing chaos in the central nervous system.

“This paper not only shows very convincing evidence of a lack of neurogenesis in the adult human hippocampus but also shows that some of the evidence presented by other studies was not conclusive,” he says.

Dividing neural progenitors in the granule cell layer (GCL) are rare at 17 gestational weeks (orthogonal views, inset) but were abundant in the ganglionic eminence at the same age (data not shown). Dividing neural progenitors were absent in the GCL from 22 gestational weeks to 55 years.

Steven Goldman, a neurologist at the University of Rochester Medical Center and the University of Copenhagen, said, “It’s by far the best database that has ever been put together on cell turnover in the adult human hippocampus. The jury is still out about whether there are any new neurons being produced.” He added that if there is neurogenesis, “it’s just not at the levels that have been presumed by many.”

The debate still goes on. No one really seems to know the answer yet, but I think that’s a positive — the controversy will generate a new wave of research on the subject.