Climate change may be vastly underestimated due to ocean temperature miscalculations - study

Scientists have discovered a flaw in the method used to measure past ocean temperatures which, if correct, could mean we have underestimated the rate of climate change over the past 100 million years.

According to the current methodology, the temperature of the ocean depths, and the surface of the polar ocean, was some 15C (59F) higher 100 million years ago, compared to now.

These estimates have been challenged, however, by a joint team of researchers from the French National Center for Scientific Research (CNRS) and the Swiss Federal Institute of Technology in Lausanne (EPFL).

In their study, published in Nature Communications, the team posits that ocean temperatures may have remained relatively stable throughout this period, raising serious concerns about the current level of climate change being experienced by Mother Earth.

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“If we are right, our study challenges decades of paleoclimate research,” EPFL’s Anders Meibom said. “Oceans cover 70 percent of our planet. They play a key role in the Earth's climate. Knowing the extent to which their temperatures have varied over geological time is crucial if we are to gain a fuller understanding of how they behave and to predict the consequences of current climate change more accurately.”

Researchers believe that over the last 50 years certain processes used in current methodology were overlooked. Scientists have used foraminifera, which are tiny marine fossils found in the sediment cores extracted from the ocean floor, to calculate ocean temperatures.

This is done by calculating the levels of oxygen-18 content in the calcareous shells of foraminifera. The level of oxygen-18 is dependent on the temperature of the ocean in which the foraminifera live.

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The problem now, it seems, is that all of these estimates were based on the principle that the oxygen-18 content remained constant while the fossils were in the sediment. To test this theory, the team exposed the foraminifera to high temperatures in simulated seawater that only contained oxygen-18.

The results show that “the level of oxygen-18 present in the foraminifera tests can in fact change without leaving a visible trace, thereby challenging the reliability of their use as a thermometer.”

“What appeared to be perfectly preserved fossils are in fact not,” CNRS researcher Sylvain Bernard said. This basically means that previous estimates of ocean temperatures are simply incorrect and instead of showing the aforementioned 15C-degree drop over the last 100 million years, the study notes that “these measurements simply reflect the change in oxygen-18 content in the fossil foraminifera tests.”

“This change appears to be the result of a process called re-equilibration: during sedimentation, temperatures rise by 20 to 30C, causing the foraminifera tests to re-equilibrate with the surrounding water,” the study says.

But what next? Well, Meibom says scientists will now have to revisit the ocean's paleotemperatures and “carefully quantify this re-equilibration, which has been overlooked for too long.”

The researchers say that they will now focus on a number of other marine organisms to see if they can “clearly understand what took place in the sediment over geological time.”

 

Depression strongly linked to higher long-term risk of early death for both women, men

Despite increased awareness about mental illness, depression remains strongly linked to a higher risk of early death -- and this risk has increased for women in recent years -- according to results from the 60-year Stirling County Study published in CMAJ (Canadian Medical Association Journal).

"There is less stigma associated with depression, better treatments are available, but depression's link to mortality still persists," said Dr. Stephen Gilman of the Eunice Kennedy Shriver National Institute of Child Health and Human Development, part of the National Institutes of Health in Bethesda, Maryland. "At first, the association was limited to men, but in later years it was seen for women as well."

The Stirling County Study, begun in 1952 in Atlantic Canada, is well-known internationally as one of the first community-based studies on mental illness. A researcher from the original study, Dr. Jane Murphy with Massachusetts General Hospital and Harvard Medical School, Boston, Massachusetts, is a coauthor on this latest research study.

An international team of researchers looked at 60 years of mental health data on 3410 adults during 3 periods (1952-1967, 1968-1990 and 1991-2011) from a region in Atlantic Canada and linked the data to deaths in the Canadian Mortality Database. They found that the link between depression and an increased risk of death was observed in all decades of the study among men, whereas it emerged among women beginning in the 1990s. The risk of death associated with depression appeared strongest in the years following a depressive episode, leading the authors to speculate that this risk could be reversed by achieving remission of depression.

The mean age of participants at enrolment in the study was about 49 years. "The lifespan for young adults with depression at age 25 was markedly shorter over the 60-year period, ranging from 10 to 12 fewer years of life in the first group, 4 to 7 years in the second group and 7 to 18 fewer years of life in the 1992 group," says Dr. Ian Colman, Canada Research Chair in the School of Epidemiology, University of Ottawa, Ottawa, Ontario. "Most disturbing is the 50% increase in the risk of death for women with depression between 1992 and 2011."

Though depression has also been linked with poorer diet, lack of exercise, smoking and alcohol consumption -- all factors that can result in chronic health conditions -- these did not explain the increased risk of death associated with depression in this study.

Societal change may help explain the emergent risk of death for women with depression.

"During the last 20 years of the study in which women's risk of death increased significantly, roles have changed dramatically both at home and in the workplace, and many women shoulder multiple responsibilities and expectations," says Dr. Colman.

The authors suggest that family physicians should monitor patients for mood disturbances, especially recurrent episodes of depression, so that they may offer treatment and support.

Limitations include a long interval between participant interviews which prevented determining the exact timing of depression and the participants' experiences of recurrent episodes of depression between interviews.

New research opens the door to 'functional cure' for HIV

In findings that open the door to a completely different approach to curing HIV infections, scientists from the Florida campus of The Scripps Research Institute (TSRI) have for the first time shown that a novel compound effectively suppresses production of the virus in chronically infected cells, and prevents viral rebound, even when those infected cells are subjected to vigorous stimulation.

The study, led by TSRI Associate Professor Susana Valente, was published online Oct. 17 before print in the journal Cell Reports.

"No other anti-retroviral used in the clinic today is able to completely suppress viral production in infected cells in vivo," Valente said. "When combining this drug with the standard cocktail of anti-retrovirals used to suppress infection in humanized mouse models of HIV-1 infection, our study found a drastic reduction in virus RNA present -- it is really the proof-of-concept for a 'functional cure.'"

Valente, a pioneer in this new approach, calls it "Block-and-Lock" -- the approach blocks reactivation of the virus in cells, even during treatment interruptions, and locks HIV into durable state of latency.

Valente and her colleagues use a derivative of a natural compound called didehydro-Cortistatin A (dCA), which blocks replication in HIV-infected cells by inhibiting the viral transcriptional activator, called Tat, halting viral production, reactivation and replenishment of the latent viral reservoir.

"Combining dCA with anti-retroviral therapy accelerates HIV-1 suppression and prevents viral rebound after treatment interruption, even during strong cellular activation," Valente said. "It's important to note that our study uses the maximum tolerable dose of the drug -- with virtually no side effects."

The scientists studied the combination therapy in a mouse model of HIV latency and persistence. Once the combined treatment regimen was halted, viral rebound was delayed up to 19 days, compared with just seven days in mouse models receiving only anti-retroviral treatment.

"This demonstrates the potential of 'block-and-lock' strategies," said TSRI Research Associate Cari F. Kessing, co-first author of the study. "This study shows that a 'functional cure' approach can succeed in reducing residual virus in the blood during anti-retroviral treatment and limiting viral rebound during treatment interruption."

"In half of the dCA treated mice, the virus was undetectable for 16 days after all treatment was halted," said the University of North Carolina's Christopher Nixon, another first author.

"We blocked Tat, and the cell's machinery did the rest," said TSRI Research Associate Chuan Li, a coauthor of the study. "The result was that the HIV promoter becomes repressed."

Valente pointed out that the animal models were exposed to just a single month of treatment. "That's a relatively short period of time," she said. "We think longer treatments will result in longer, or even permanent, rebound delays. The question is how long? We're studying that now."

Because any viral rebound of HIV comes with a host of adverse effects, Valente noted, blocking that rebound would automatically reduce those effects.

"This is the only class of drugs that stops infected cells from making viruses outright," said Valente. "All current antivirals work later in the viral lifecycle, so only a HIV transcriptional inhibitor like dCA can stop the side effects of low-level virus production."

In addition to Valente, Kessing, Li and Nixon, other authors of the study, "In Vivo Suppression Of HIV Rebound By Didehydro-1 Cortistatin A, A 'Block-And-Lock' Strategy For HIV-1 Treatment," are Guillaume Mousseau and Mohammad Fallahi of TSRI; Perry M. Tsai, Phong T. Ho, Jenna B. Honeycutt and J. Victor Garcia of the University of North Carolina; and Hiroshi Takata and Lydie Trautmann of Walter Reed Army Institute of Research and the Henry M. Jackson Foundation for the Advancement of Military Medicine.

 

6th mass extinction event could happen by 2100 – study

Over the past 540 million years Earth has suffered five mass extinction events, the worst of which wiped out more than 9 per cent of marine life on the planet. A new study has suggested that the next such catastrophe might not be too far away.

Massachusetts Institute of Technology (MIT) geophysicist and mathematician, Daniel Rothman has been busy studying previous mass extinctions. He reckons the next one might be a mere 83 years away.

The previous five catastrophic events each unfolded over millions of years and involved the natural cycle of carbon through the oceans and atmosphere being disturbed, resulting, in some cases, the death of almost all life on Earth.

The award-winning mathematician identified two “thresholds of catastrophe” that, if exceeded, would upset the natural order of the cycle, leading to an unstable environment and eventually a mass extinction.

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The first relates to changes in the carbon cycle over a period of thousands or millions of years. A mass extinction will occur if the rate of change in the cycle occurs faster than global ecosystems can adapt.

The second pertains to the size or magnitude of the carbon flux over a shorter period, as has been the case over the last century.

Therein lies a problem, however, as Rothman says“How can you really compare these great events in the geologic past, which occur over such vast timescales, to what's going on today, which is centuries at the longest?”

“So I sat down one summer day and tried to think about how one might go about this systematically.”

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Following this, he devised a mathematical formula to determine the total mass of carbon added to the oceans during each event, after which “it became evident that there was a characteristic rate of change that the system basically didn't like to go past.”

Rothman estimates this to be 310 gigatons. He thinks that given the rise of carbon dioxide over the last century, a sixth mass extinction could be on the way as estimates suggest that humans will add roughly 310 gigatons to the cycle by 2100.

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“This is not saying that disaster occurs the next day,” Rothman said. “It’s saying that, if left unchecked, the carbon cycle would move into a realm which would be no longer stable, and would behave in a way that would be difficult to predict. In the geologic past, this type of behavior is associated with mass extinction.”

Rothman's paper was published Wednesday in the journal Science Advances.

What makes alcoholics drink? Research shows it's more complex than supposed

What makes alcoholics drink? New research has found that in both men and women with alcohol dependence, the major factor predicting the amount of drinking seems to be a question of immediate mood. They found that suffering from long-term mental health problems did not affect alcohol consumption, with one important exception: men with a history of depression had a different drinking pattern than men without a history of depression; surprisingly those men were drinking less often than men who were not depressed

"This work once again shows that alcoholism is not a one-size-fits-all condition," said lead researcher, Victor Karpyak (Mayo Clinic, MN, USA). "So the answer to the question of why alcoholics drink is probably that there is no single answer; this will probably have implications for how we diagnose and treat alcoholism."

The work, presented at the ECNP congress by researchers from the Mayo Clinic*, determined the alcohol consumption of 287 males and 156 females with alcohol dependence over the previous 90 days, using the accepted Time Line Follow Back method and standardized diagnostic assessment for life time presence of psychiatric disorders (PRISM); they were then able to associate this with whether the drinking coincided with a positive or negative emotional state (feeling "up" or "down"), and whether the individual had a history of anxiety, depression (MDD) or substance abuse.

The results showed that alcohol dependent men tended to drink more alcohol per day than alcohol dependent women. As expected, alcohol consumption in both men and women was associated with feeling either up or down on a particular day, with no significant association with anxiety or substance use disorders. However, men with a history of major depressive disorder had fewer drinking days (p=0.0084), and fewer heavy drinking days (p=0.0214) than men who never a major depressive disorder.

Victor Karpyak continued: "Research indicates that many people drink to enhance pleasant feelings, while other people drink to suppress negative moods, such as depression or anxiety. However, previous studies did not differentiate between state-dependent mood changes and the presence of clinically diagnosed anxiety or depressive disorders. The lack of such differentiation was likely among the reasons for controversial findings about the usefulness of antidepressants in treatment of alcoholics with comorbid depression.

This work will need to be replicated and confirmed, but from what we see here, it means that the reasons why alcoholics drink depend on their background as well as the immediate circumstances. There is no single reason. And this means that there is probably no single treatment, so we will have to refine our diagnostic methods and tailor treatment to the individual. It also means that our treatment approach may differ depending on targeting different aspects of alcoholism (craving or consumption) and the alcoholic patient (i.e. man or a woman) with or without depression or anxiety history to allow really effective treatment."

Commenting, Professor Wim van den Brink (Professor of Psychiatry and Addiction at the Academic Medical Centre, University of Amsterdam) said:

"This is indeed a very important issue. Patients with an alcohol use disorder often show a history of other disorders, including mood and anxiety disorders, they also often present with alcohol induced anxiety and mood disorders and finally the may report mood symptoms that do not meet criteria for a mood or anxiety disorder (due to a failure to meet the minimal number of criteria or a duration of less than two weeks). All these different conditions may influence current levels or patterns of drinking.

The current study seems to show that the current presence of mood/anxiety symptoms is associated with more drinking in both male and female alcoholics, whereas a clinical history of major depression in male alcoholics is associated with lower current dinking levels. Although, the study does not provide a clear reason for this difference, it may have consequences for treatment. For example, antidepressant treatment of males with a history major depression may have no effect on drinking levels. However, these findings may also result from residual confounding, e.g. patients with a history of major depression might also be patients with a late age of onset of their alcohol use disorder and this type of alcohol use disorder is associated with a different pattern of drinking with more daily drinking and less heavy drinking days and less binging. More prospective studies are needed to resolve this important but complex clinical issue."

*This work was presented on Sunday 3rd September, 2017.

Moon has a water-rich interior

A new study of satellite data finds that numerous volcanic deposits distributed across the surface of the Moon contain unusually high amounts of trapped water compared with surrounding terrains. The finding of water in these ancient deposits, which are believed to consist of glass beads formed by the explosive eruption of magma coming from the deep lunar interior, bolsters the idea that the lunar mantle is surprisingly water-rich.

Scientists had assumed for years that the interior of the Moon had been largely depleted of water and other volatile compounds. That began to change in 2008, when a research team including Brown University geologist Alberto Saal detected trace amounts of water in some of the volcanic glass beads brought back to Earth from the Apollo 15 and 17 missions to the Moon. In 2011, further study of tiny crystalline formations within those beads revealed that they actually contain similar amounts of water as some basalts on Earth. That suggests that the Moon's mantle -- parts of it, at least -- contain as much water as Earth's.

"The key question is whether those Apollo samples represent the bulk conditions of the lunar interior or instead represent unusual or perhaps anomalous water-rich regions within an otherwise 'dry' mantle," said Ralph Milliken, lead author of the new research and an associate professor in Brown's Department of Earth, Environmental and Planetary Sciences. "By looking at the orbital data, we can examine the large pyroclastic deposits on the Moon that were never sampled by the Apollo or Luna missions. The fact that nearly all of them exhibit signatures of water suggests that the Apollo samples are not anomalous, so it may be that the bulk interior of the Moon is wet."

The research, which Milliken co-authored with Shuai Li, a postdoctoral researcher at the University of Hawaii and a recent Brown Ph.D. graduate, is published in Nature Geoscience.

Detecting the water content of lunar volcanic deposits using orbital instruments is no easy task. Scientists use orbital spectrometers to measure the light that bounces off a planetary surface. By looking at which wavelengths of light are absorbed or reflected by the surface, scientists can get an idea of which minerals and other compounds are present.

The problem is that the lunar surface heats up over the course of a day, especially at the latitudes where these pyroclastic deposits are located. That means that in addition to the light reflected from the surface, the spectrometer also ends up measuring heat.

"That thermally emitted radiation happens at the same wavelengths that we need to use to look for water," Milliken said. "So in order to say with any confidence that water is present, we first need to account for and remove the thermally emitted component."

To do that, Li and Milliken used laboratory-based measurements of samples returned from the Apollo missions, combined with a detailed temperature profile of the areas of interest on the Moon's surface. Using the new thermal correction, the researchers looked at data from the Moon Mineralogy Mapper, an imaging spectrometer that flew aboard India's Chandrayaan-1 lunar orbiter.

The researchers found evidence of water in nearly all of the large pyroclastic deposits that had been previously mapped across the Moon's surface, including deposits near the Apollo 15 and 17 landing sites where the water-bearing glass bead samples were collected.

"The distribution of these water-rich deposits is the key thing," Milliken said. "They're spread across the surface, which tells us that the water found in the Apollo samples isn't a one-off. Lunar pyroclastics seem to be universally water-rich, which suggests the same may be true of the mantle."

The idea that the interior of the Moon is water-rich raises interesting questions about the Moon's formation. Scientists think the Moon formed from debris left behind after an object about the size of Mars slammed into the Earth very early in solar system history. One of the reasons scientists had assumed the Moon's interior should be dry is that it seems unlikely that any of the hydrogen needed to form water could have survived the heat of that impact.

"The growing evidence for water inside the Moon suggest that water did somehow survive, or that it was brought in shortly after the impact by asteroids or comets before the Moon had completely solidified," Li said. "The exact origin of water in the lunar interior is still a big question."

In addition to shedding light on the water story in the early solar system, the research could also have implications for future lunar exploration. The volcanic beads don't contain a lot of water -- about .05 percent by weight, the researchers say -- but the deposits are large, and the water could potentially be extracted.

"Other studies have suggested the presence of water ice in shadowed regions at the lunar poles, but the pyroclastic deposits are at locations that may be easier to access," Li said. "Anything that helps save future lunar explorers from having to bring lots of water from home is a big step forward, and our results suggest a new alternative."

The research was funded by the NASA Lunar Advanced Science and Exploration Research Program (NNX12AO63G).


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Drinking coffee could reduce chance of early death, scientists say

Drinking around three cups of coffee a day has been linked to a lower risk of death “from any cause” in two new large-scale studies.

The habits of coffee-lovers were shown to add years to their life – with high coffee consumption shown to reduce the risk of death from diseases related to circulation and digestion in particular.

While scientists say more research is needed to prove coffee is definitely behind the effects observed in the studies, experts believe the antioxidant plant compounds found in the drink, rather than its caffeine, are responsible for its potentially life-extending effect.

Researchers from Imperial College London and the International Agency for Research on Cancer (IARC) analysed data on the health and coffee-drinking habits of more than half a million people from 10 European countries, including the UK.

They found men who drank at least three cups of coffee a day were 18 per cent less likely to die from any cause than non-coffee drinkers, with women experiencing an eight per cent reduction in mortality over the same period.

Meanwhile, American scientists conducted a separate investigation into the effect of coffee on the health of more than 185,000 participants from different ethnic backgrounds.

People who drank one cup of coffee daily were 12 per cent less likely to die than those who drank no coffee, irrespective of ethnicity, while drinking two to three cups of coffee appeared to reduce the chances of death by 18 per cent.

Experts praised the robust nature of the studies, but warned that further research was needed to prove that the effects observed were caused by the coffee itself, and not other factors.

The US study’s lead author, Dr Veronica Setiawan, from the University of Southern California, said the chemical make-up of the popular beverage was a possible explanation for the findings.

“Coffee contains a lot of antioxidants and phenolic compounds that play an important role in cancer prevention,” she said.

“We cannot say drinking coffee will prolong your life, but we see an association. If you like to drink coffee, drink up! If you’re not a coffee drinker, then you need to consider if you should start.”

Whether the coffee contained caffeine or was decaffeinated did not appear to make a difference in the two studies, both published in the journal Annals of Internal Medicine.

The studies were adjusted for a number of lifestyle factors, such as smoking and diet, to try and isolate and analyse the effects of coffee drinking on health and mortality rates.

Commenting on the research, statistics expert Professor Kevin McConway, from The Open University, said both papers were “well-conducted and large, and show similar results across several different populations and ethnic groups”.

“As a coffee drinker myself, they do reassure me that my habit probably isn’t bad for me,” he said. “However, if I didn’t already drink coffee, I’m not sure that they would persuade me to take it up for the good of my health.  

“That’s because the size of the potential protective effect of coffee, in these studies, is not very large; because we can’t be sure what is causing what; and because, even if coffee drinking is somehow directly improving people’s health on average, neither study throws much light on exactly how it might do that.”

Heart failure is associated with loss of important gut bacteria

In the gut of patients with heart failure, important groups of bacteria are found less frequently and the gut flora is not as diverse as in healthy individuals. Data obtained by scientists of the German Centre for Cardiovascular Research (DZHK) provide valuable points of departure for understanding how gut colonisation is associated with the development and progress of heart failure. It has long been known that heart failure and gut health are linked. The gut, thus, has a worse blood supply in instances of heart failure; the intestinal wall is thicker and more permeable, whereby bacteria and bacterial components may find their way into the blood. Moreover, scientists know that the composition of the gut bacteria is altered in other widespread diseases such as type 2 diabetes. Against this backdrop, researchers at the DZHK site Hamburg/Kiel/Lübeck investigated whether and how the gut flora in patients with heart failure changes.

In order to do this, they analysed the gut bacteria in stool samples of healthy individuals and patients with heart failure. The project headed by Professor Norbert Frey of the University Hospital Schleswig-Holstein, Campus Kiel, was conducted in close cooperation with Professor Andre Franke's team at the Christian-Albrechts-Universität zu Kiel, which found that the sections of the bacterial genome deciphered the distinction of the microorganism. The results showed that a significantly lower proportion of different bacteria are found in the gut in patients with heart failure than in healthy controls. Individual important families of bacteria are significantly reduced. It is still unclear whether the gut flora is altered as a result of heart failure or whether it may be a trigger for this disease.

Influential factors: diet, medication, smoking

"Of course, other factors also affect the composition of our gut bacteria. We know that the gut flora of a vegan who starts eating meat changes within three days," explains associate professor Dr. Mark Lüdde of the University Hospital Schleswig-Holstein, Campus Kiel. For this reason, we asked the Kiel-based researchers of dietary habits beforehand. Individuals with an extreme diet, such as a vegan diet, were not allowed to participate in their study. Instead, they chose individuals with a standard diet comprising both meat and vegetables for both groups.

In addition to diet, medication also affect the gut flora. It was, therefore, important that the control group also took medicinal products that patients with heart failure must take routinely. Antibiotics could not have been administered for at least three months prior. Smokers were also included in both groups. All participants were from the same region and were the same age; gender distribution and BMI were equal in both groups.

Consequence or cause of the disease?

The observed pattern of the reduced genera and families of bacteria seems very characteristic of heart failure, which is why these results may be new points of departure for therapies. The differences between healthy individuals and those with heart failure, thus, came about mainly through the loss of bacteria of the genera Blautia and Collinsella, as well as two previously unknown genera that belong to the families Erysipelotrichaceae and Ruminococcaceae.

Other research projects have shown that the occurrence of Blautia curbs inflammations. Similarly, the genus Faecalibacterium is associated with anti-inflammatory mechanisms. It is, however, not only reduced in patients with heart failure. Since heart failure is accompanied by a chronic inflammation, one theory is that the gut flora fosters the systemic inflammation. Yet generally scientists currently believe that the gut flora changes as a consequence of heart failure. Lüdde and his colleagues believe it is plausible that an altered bacterial profile could also be a risk factor or an early disease marker for heart failure. This is supported by the recent characterisation of trimethylamine N-oxide (TMAO), a metabolic product of gut bacteria, as an independent risk factor for the mortality rate in patients with heart failure. Further investigations are scheduled to clarify the cause and effect of altered gut flora in patients with heart failure. The scientists anticipate obtaining new knowledge on how heart failure occurs and progresses.


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