The fruit Garcinia cambogia was once just the less popular cousin of a trendy fruit, the mangosteen. But now, nutritional supplements containing Garcinia cambogia extract have become the rage, touted for their purported ability to curb appetite and stop weight gain.
The gambooge fruit, also known as the Malabar tamarind, grows across southwest India, Myanmar and Indonesia. It ripens to a red or yellowish fruit about the size of an orange, but resembling the shape of a pumpkin.
People have long used the dried gambooge rinds for chutneys or curries, and sometimes as an aid for stomach problems. But in the late 1960s, scientists identified a substance in the rind of the fruit called hydroxycitric acid, or HCA, which has some potentially attractive qualities.
“Some studies have shown that HCA stops an enzyme that turns sugar into fat,” said Catherine Ulbricht, senior pharmacist at Massachusetts General Hospital in Boston and co-founder of Natural Standard Research Collaboration, which reviews evidence on herbs and supplements.
A fruit extract that could interfere with the body’s production of fat? The appeal is obvious. However, good results in test tubes don’t always translate to an entire person.
Some studies say HCA works, and some say it doesn’t. Animal studies of HCA showed that mice taking the substance ate less, lost weight and produced less fat from sugar.
Human studies had more conflicting results. One weight loss trial showed no difference between people who took Garcinia cambogia and those who took a placebo pill. Other trials linked HCA to weight loss and healthy blood lipid levels (lipids are fats).
“Further, well-designed clinical trials are needed before any firm conclusions can be made,” Ulbricht said.
If a pharmaceutical company wanted to sell HCA as a drug, the company would have to find stronger evidence that the substance worked, coming from better-designed clinical trials. Without that data, HCA wouldn’t pass U.S. Food and Drug Administration approval, Ulbricht said. But the FDA doesn’t put chemicals sold as nutritional supplements under the same burden of proof as pharmaceuticals. In fact, supplement makers only have to make their products safe to eat and responsibly label them.
Despite the popularity of Garcinia cambogia, it is difficult to track how effective supplements containing it are.
“Preparation of products may vary from manufacturer to manufacturer, and from batch to batch within one manufacturer,” Ulbricht said. That makes it difficult to compare one brand to another or even to measure the effects of a single brand.
People may safely eat the fruit, of course. And clinical trials have shown it’s safe to take Garcinia cambogia extract by mouth — at least for 12 weeks, the length of the studies.
But take caution. Garcinia cambogia has side effects – it may lower a person’s blood sugar, so it can interact with diabetes treatments. The fruit hasn’t been adequately studied in pregnant women or women who breastfeed. And Garcinia cambogia may be a problem for patients with Alzheimer’s or other forms of dementia, Ulbricht said.
In 2009, the FDA issued a safety warning after receiving more than 20 reports of severe reactions, including liver damage, in people taking the supplement Hydroxycut. At the time, Hydroxycut contained Garcinia cambogia extract and other compounds, including chromium polynicotinate and Gymnema sylvestre extract.
Ulbricht said it’s unclear if the Garcinia cambogia extract caused the liver damage.
The bottom line is that people should tell their doctors before trying a new supplement, including Garcinia cambogia and HCA, she said.
A new study of anthrax reveals why the infection is deadly.
The findings also offer clues that could be used to better treat people who are infected, which could possibly improve survival rates, researchers said in their study published Thursday (Aug. 29) in the journal Nature.
Doctors in developed nations rarely see anthrax cases, but if they do, it’s important to treat the disease correctly, and as soon as possible, said Stephen Leppla, of the Laboratory for Infectious Diseases at the National Institutes of Health.
“The problem with clinicians treating anthrax is that nobody has much experience doing it,” Leppla said. Understanding exactly how anthrax kills can help clinicians tailor better strategies.
Anthrax is caused by bacteria, and can infect people in one of three ways: people might inhale the spores, eat the spores, or take in spores via the skin. All three types of infection can be deadly, though the skin route of infection is much less so, according to the Centers for Disease Control and Prevention. Inhaled anthrax has a mortality rate of about 75 percent, while the gastrointestinal infection kills about 60 percent of infected people, even with treatment. Among those infected through their skin, anthrax mortality drops to 20 percent. [Tiny & Nasty: Images of Things That Make Us Sick]
In the developing world, people become infected though contact with livestock. In the U.S. and Europe, anthrax is now very rare – only one or two cases appear yearly on average in the U.S.
The bacteria themselves aren’t what sickens and kills: it’s the toxins the bacteria produce. A doctor can treat a patient with antibiotics and kill all the anthrax bacteria – antibiotics are very effective against the infection. But the toxins the bacteria made remain in the body, and continue damaging cells.
The two toxins produced by anthrax, called lethal toxin and edema toxin, damage many types of cells, but it was thought that their effects on endothelial cells, which line blood and lymph vessels, were what made anthrax so lethal.
In the new study, it was found that wasn’t the case; rather, much of the toxins’ action seems to be in the cells of the heart muscle and the liver.
To track down which cells anthrax targeted, the researchers looked at mice genetically altered so that a protein called CMG2, to which anthrax toxins bind, was absent from their endothelial cells. They compared these mice with another group that had CMG2.
Results showed that both sets of mice were similarly sensitive to anthrax, which meant that anthrax wasn’t killing the mice via damage to endothelial cells.
The researchers next tested mice that were missing the CMG2 protein from their heart cells. Those mice survived the doses of lethal toxin much better than their litter mates that had the protein, which pointed to anthrax’s effects on the heart muscle as the way that it kills.
Similarly, mice without CMG2 in their liver cells fared better when exposed to edema toxin than mice that expressed CMG2, showing that the edema toxin affects the liver.
Leppla noted that it is not clear whether the findings are also true of anthrax in people. Future experiments on primates would confirm the results, he said.
India may contain a natural trove of diamonds previously overlooked by prospectors, new research shows.
Canada, Russia and southern Africa currently dominate the world diamond market. But, in recent years, geologists have debated whether southeast India could produce large quantities of diamonds as well. Now, research from a group of geologists at the National Geophysical Research Institute in Hyderabad, India, suggests that southeastern regions of the country do, in fact, contain the right ingredients for these gems to form in abundance. A report of their findings appeared earlier this month in the journal Lithosphere.
Diamonds form deep within the Earth’s mantle and erupt to the surface within volcanic rocks called kimberlites and lamproites. The team discovered such diamond-bearing rocks by chance while conducting an unrelated geologic survey and decided to investigate the sites further as a side project.
“We thought that it may be a good idea to conduct further research on this crucial aspect to propose a suitable and cost-effective reconnaissance technique that can be deployed as a quick search tool over large areas for diamond prospecting,” said geologist Subrata Das Sharma, an author on the paper. [Shine On: Photos of Dazzling Mineral Specimens]
Instead of tediously searching an entire landscape for diamond-bearing rocks — which tend to crumble easily and are often difficult to identify — geologists have devised a variety of techniques to search for key diamond-forming conditions within the mantle, and then later explore promising areas on land.
These diamond-forming conditions include extremely high temperatures and pressures, found only in the deepest depths of theEarth’s lithosphere — a region including the entire Earth’s crust and the solid upper mantle that rests above the more molten lower mantle where crystals melt into magma.
Without the heat and pressure of the deep lithosphere, carbon — the only ingredient in diamonds — takes on the less valuable form of graphite.
The lithosphere varies in thickness across the planet, and does not always reach depths deep enough to facilitate diamond growth. Das Sharma and his team sought to find out how thick the lithosphere is under India, and did so by looking at seismic data collected during several relatively recent earthquakes. Since seismic waves travel at different speeds and amplitudes depending on the material they pass through, seismic data can reveal the transition from the hard upper mantle to the molten lower mantle, which is the lower boundary of the lithosphere.
Previous studies based on seismic data have suggested that southeastern India rests atop a thin portion of the lithosphere. But Das Sharma and his team reanalyzed related data using different techniques, and discovered a signal much deeper indicating the lithosphere reaches down far enough to facilitate diamond growth.
The team also examined existing analyses of the chemical composition of nearby rocks on the surface to further confirm that the temperature and pressure conditions would have been extreme enough to support diamond growth.
Indian diamond mining?
Ultimately, the researchers identified a region wider than 120,000 square miles (200,000 square kilometers) across southeastern India that could potentially contain diamond-bearing rocks.
These findings could lead to increased diamond mining in the country, but this will depend on the interests of mining companies, Das Sharma said.
“Diamond mining could become viable once an appropriate mining strategy is worked out,” Das Sharma said. “This needs concerted efforts in field detection of generally obscured kimberlites and lamproites in a region.” [Infographic: Tallest Mountain to Deepest Ocean Trench]
While the team’s techniques are relatively quick and cheap, geologists elsewhere have developed other efficient methods for diamond prospecting as well. For example, some use electromagnetic tools that measure the conductivity of the mantle in search of carbon-rich areas (because carbon is highly conductive, or allows for the easy flow of electrons), while others use seismic imaging techniques that illustrate physical boundaries within the mantle.
Still, this new study demonstrates how to use effective and relatively cheap techniques that could help smooth the way for future diamond exploration programs around the world, according to Alan Jones, a geologist at the Dublin Institute for Advanced Studies in Ireland who was not involved in the study.
“This has really cleared up this Indian lithosphere issue,” Jones told LiveScience. “In terms of global impact, I would say the paper is on part of the cutting edge along with other people’s work.”
The team members plan to share their results with the Indian government, and to continue honing their research methods to develop even more efficient diamond-hunting techniques.
Black diamonds, also known as carbonados, are dark, porous, and found only in Brazil and Central Africa. And they don’t come from volcanoes — they come from outer space.
Carbonados don’t look like much when they’re first yanked out of the ground, but that doesn’t differentiate them much from other diamonds. They’re as hard as other diamond and polish up similarly to create lustrous jewelry. They’re just a little different because they’re extraterrestrials. While most diamonds on Earth are the result of carbon being crushed and heated beneath volcanoes, the porous black carbonados are meteorites formed during supernova explosions.
The diamonds’ locations were the first clue that led scientists to believe that carbonados are not homegrown. Although diamonds of every kind are found all over Earth, only Brazil and the Central African Republic are known to possess carbonado deposits.
These two zones don’t possess anything that other diamond-mining sites lack — these diamonds were produced by something other than the geology of the area.
Two things caused carbonado researchers to look to space: nitrogen and hydrogen. The distribution of both elements in black diamonds was examined through infrared spectroscopy. Scientists heated the stones up and examined them with spectroscopes, which revealed that nitrogen was present in single atoms, not in aggregates like other gems. The scopes also revealed a lot of hydrogen layered on the stones. In sum, the spectroscopy resembled most closely the kind of emission and absorption spectra seen on meteors and in post-supernovae systems.
These diamond offer a fascinating snapshot of the Earth’s history. Sometime in the past, our planet came into contact with the detritus of a 2-to-3-billion-year-old supernova. A meteor of the surviving material drifted from the nova to earth, possibly in a chunk as much as a mile wide, broke up as it hit earth’s atmosphere, and landed over South America and Africa.
Those chunks of meteor were chewed into pieces by the earth and have been unearthed today as dark and unearthly crystals. And while it’s true that we’re all stardust, it’s pretty insane to wear a chunk of multi-billion-year-old space stone on your hand.
Somewhere between 7,500-4,000 years ago, a meteorite fragmented over Estonia’s Saaremaa island. The meteorite hit with a force comparable to Hiroshima and left nine impact craters, including the 110-meter Kaali crater. Locals worshiped this hole as holy.
Says Atlas Obscura:
Several kilometers above the earth’s surface, the meteorite broke into pieces from the pressure and heat of the atmosphere. The resulting chunks collided into Saaremaa with the force of a small nuclear bomb, wreaking havoc on the landscape and possibly claiming numerous victims.
The explosion left nine total craters, now known as the Kaali Meteorite Crater Field. Some of these craters are quite small: one measures only twelve meters across and one meter deep. But the most interesting of the group is the largest crater, a gently sloping bowl filled with stagnant, murky water.
Simply known as Kaali crater, the largest crater (which measures 110 meters across) is believed to have been a sacred site for many centuries, in part due to its cosmic origin. Surrounding Kaali crater are the remains of an immense stone wall from the Late Bronze Age, stronger than any similar structures in the region and providing clues to the crater’s use by ancient peoples.
1500-to-2000-year-old animal remains found around Kaali Lake have led archaeologists to believe that the crater was the site of ritualistic sacrifices. You can read more about the geology and formation of the Kaali crater at Geologos.
[Photos via CarlosJ’s Flickr]
By Kaushik Friday, August 16, 2013
The Al Wahaba crater is located in the Saudi Arabian desert, 254 km from Taif on the western edge of the Hafer Kishb basalt plateau, which contains many volcanic cones. This photogenic crater is the largest of its kind in the Middle East – 2 km in diameter with cliffs dropping 250 meters to a flat base, in the center of which is a thick crust of dazzling white sodium phosphate crystals.
For some time it was thought that the crater was formed by a meteorite, as its appearance resembles that of the Barringer Crater, with its circular form and high sides. It is now commonly accepted by geologists that the crater was formed by volcanic activity in the form of an underground explosion of steam generated when molten magma came into contact with groundwater. On one side of the crater lies an ash cone which is all that is left of the volcano.
The crater is situated in an area where there was intense volcanic activity in the past. The surrounding sandy plain is in fact a bed of volcanic ash. To the north-west is a mound with a vertical face on the edge of the crater, which was an earlier volcano, split in half when the crater was formed. In this cliff face can be seen lava-filled dykes. On the northern face of the crater are palm trees and green grass.