Friday, August 08, 2008

Vitamin C slows cancer in mice

Oxygen for the vitamin C freaks. If you do enough studies, one will come "right" by chance alone. Pesky that you've got to inject it rather than eat it, though

HIGH doses of vitamin C injections reduced the size of tumours and slowed cancerous growths by about 50 per cent in laboratory mice, according to US research released today. Researchers at the National Institutes of Health noted the phenomenon in brain, ovarian and pancreatic cancers, according to findings published in the August 5 issue of the Proceedings of the National Academy of Sciences.

"Researchers discovered that high concentrations of ascorbate had anticancer effects in 75 per cent of cancer cell lines tested, while sparing normal cells," the report said. "The researchers traced ascorbate's anti-cancer effect to the formation of hydrogen peroxide in the extracellular fluid surrounding the tumours. Normal cells were unaffected," it said. Injections were necessary because the body regulates vitamin C when ingested, so that higher doses cannot be attained.

"When you eat foods containing more than 200 milligrams of vitamin C a day - for example, two oranges and a serving of broccoli - your body prevents blood levels of ascorbate from exceeding a narrow range," said Mark Levine, the study's lead author and chief of the Molecular and Clinical Nutrition Section of the National Institute of Diabetes and Digestive and Kidney Diseases.

Scientists "injected ascorbate into the veins or abdominal cavities of rodents with aggressive brain, ovarian, and pancreatic tumours", the report said, delivering "up to four grams per kilogram of body weight daily". By injecting mice with 43 cancer and five normal cell lines, "the researchers discovered that high concentrations of ascorbate had anticancer effects in 75 per cent of cancer cell lines tested, while sparing normal cells."

Scientists involved with the study also pointed to evidence that "these high ascorbate concentrations could be achieved in people." "In immune-deficient mice with rapidly spreading ovarian, pancreatic, and glioblastoma (brain) tumours ... the ascorbate injections reduced tumour growth and weight by 41 to 53 per cent."

The researchers concluded that the findings "provide the first firm basis for advancing pharmacologic ascorbate in cancer treatment in humans." Vitamin C was considered as a possible treatment for cancer three decades ago, but subsequent studies showed oral doses provided no benefit.


High-Aptitude Minds: The Neurological Roots of Genius

Researchers are finding clues to the basis of IQ in the brain and the article excerpted below is a surprisingly positive summary of the work -- surprising for SciAm. I have long been saying that high IQ is usually just one aspect of general biological good functioning and the work discussed below could also be seen as conducing to that conclusion

Key Concepts:

* Smarter brains tend to be bigger-at least in certain locations. Researchers have fingered parts of the parietal and frontal lobes as well as a structure called the anterior cingulate as important for superior cognition.

* Some studies suggest that the brains of brighter people use less energy to solve certain problems than those of people with lower aptitudes do. But under certain circumstances, scientists have also observed higher neuronal power consumption in individuals with superior mental capacities.

* People often overestimate the importance of intellectual ability. Practice and perseverance contribute more to accomplishment than being smart does.

Within hours of his demise in 1955, Albert Einstein's brain was salvaged, sliced into 240 pieces and stored in jars for safekeeping. Since then, researchers have weighed, measured and otherwise inspected these biological specimens of genius in hopes of uncovering clues to Einstein's spectacular intellect.

Their cerebral explorations are part of a century-long effort to uncover the neural basis of high intelligence or, in children, giftedness. Traditionally, 2 to 5 percent of kids qualify as gifted, with the top 2 percent scoring above 130 on an intelligence quotient (IQ) test. (The statistical average is 100. See the box on the opposite page.) A high IQ increases the probability of success in various academic areas. Children who are good at reading, writing or math also tend to be facile at the other two areas and to grow into adults who are skilled at diverse intellectual tasks [see "Solving the IQ Puzzle," by James R. Flynn; Scientific American Mind, October/November 2007].

Most studies show that smarter brains are typically bigger-at least in certain locations. Part of Einstein's parietal lobe (at the top of the head, behind the ears) was 15 percent wider than the same region was in 35 men of normal cognitive ability, according to a 1999 study by researchers at McMaster University in Ontario. This area is thought to be critical for visual and mathematical thinking. It is also within the constellation of brain regions fingered as important for superior cognition. These neural territories include parts of the parietal and frontal lobes as well as a structure called the anterior cingulate.

But the functional consequences of such enlargement are controversial. In 1883 English anthropologist and polymath Sir Francis Galton dubbed intelligence an inherited feature of an efficiently functioning central nervous system. Since then, neuroscientists have garnered support for this efficiency hypothesis using modern neuroimaging techniques. They found that the brains of brighter people use less energy to solve certain prob-lems than those of people with lower aptitudes do.

In other cases, scientists have observed higher neuronal power consumption in individuals with superior mental capacities. Musical prodigies may also sport an unusually energetic brain [see box on page 67]. That flurry of activity may occur when a task is unusually challenging, some researchers speculate, whereas a gifted mind might be more efficient only when it is pondering a relatively painless puzzle.

Despite the quest to unravel the roots of high IQ, researchers say that people often overestimate the significance of intellectual ability [see "Coaching the Gifted Child," by Christian Fischer]. Studies show that practice and perseverance contribute more to accomplishment than being smart does.

Size Matters

In humans, brain size correlates, albeit somewhat weakly, with intelligence, at least when researchers control for a person's sex (male brains are bigger) and age (older brains are smaller). Many modern studies have linked a larger brain, as measured by magnetic resonance imaging, to higher intellect, with total brain volume accounting for about 16 percent of the variance in IQ. But, as Einstein's brain illustrates, the size of some brain areas may matter for intelligence much more than that of others does.

In 2004 psychologist Richard J. Haier of the University of California, Irvine, and his colleagues reported evidence to support the notion that discrete brain regions mediate scholarly aptitude. Studying the brains of 47 adults, Haier's team found an association between the amount of gray matter (tissue containing the cell bodies of neurons) and higher IQ in 10 discrete regions, including three in the frontal lobe and two in the parietal lobe just behind it. Other scientists have also seen more white matter, which is made up of nerve axons (or fibers), in these same regions among people with higher IQs. The results point to a widely distributed-but discrete-neural basis of intelligence

The neural hubs of general intelligence may change with age. Among the younger adults in Haier's study-his subjects ranged in age from 18 to 84-IQ correlated with the size of brain regions near a central structure called the cingulate, which participates in various cognitive and emotional tasks. That result jibed with the findings, published a year earlier, of pediatric neurologist Marko Wilke, then at Cincinnati Children's Hospital Medical Center, and his colleagues. In its survey of 146 children ages five to 18 with a range of IQs, the Cincinnati group discovered a strong connection between IQ and gray matter volume in the cingulate but not in any other brain structure the researchers examined.

Scientists have identified other shifting neural patterns that could signal high IQ. In a 2006 study child psychiatrist Philip Shaw of the National Institute of Mental Health and his colleagues scanned the brains of 307 children of varying intelligence multiple times to determine the thickness of their cerebral cortex, the brain's exterior part. They discovered that academic prodigies younger than eight had an unusually thin cerebral cortex, which then thickened rapidly so that by late childhood it was chunkier than that of less clever kids. Consistent with other studies, that pattern was particularly pronounced in the frontal brain regions that govern rational thought processes.

The brain structures responsible for high IQ may vary by sex as well as by age. A recent study by Haier, for example, suggests that men and women achieve similar results on IQ tests with the aid of different brain regions. Thus, more than one type of brain architecture may underlie high aptitude.

Low Effort Required

Meanwhile researchers are debating the functional consequences of these structural findings. Over the years brain scientists have garnered evidence supporting the idea that high intelligence stems from faster information processing in the brain. Underlying such speed, some psychologists argue, is unusually efficient neural circuitry in the brains of gifted individuals.

Experimental psychologist Werner Krause, formerly at the University of Jena in Germany, for example, has proposed that the highly gifted solve puzzles more elegantly than other people do: they rapidly identify the key information in them and the best way to solve them. Such people thereby make optimal use of the brain's limited working memory, the short-term buffer that holds items just long enough for the mind to process them.

Starting in the late 1980s, Haier and his colleagues have gathered data that buttress this so-called efficiency hypothesis. The researchers used positron-emission tomography, which measures glucose metabolism of cells, to scan the brains of eight young men while they performed a nonverbal abstract reasoning task for half an hour. They found that the better an individual's performance on the task, the lower the metabolic rate in widespread areas of the brain, supporting the notion that efficient neural processing may underlie brilliance. And in the 1990s the same group observed the flip side of this phenomenon: higher glucose metabolism in the brains of a small group of subjects who had below-average IQs, suggesting that slower minds operate less economically.

More recently, in 2004 psychologist Aljoscha Neubauer of the University of Graz in Austria and his colleagues linked aptitude to diminished cortical activity after learning. The researchers used electroencephalography (EEG), a technique that detects electrical brain activity at precise time points using an array of electrodes affixed to the scalp, to monitor the brains of 27 individuals while they took two reasoning tests, one of them given before test-related training and the other after it. During the second test, frontal brain regions-many of which are involved in higher--order cognitive skills-were less active in the more intelligent individuals than in the less astute subjects. In fact, the higher a subject's mental ability, the bigger the dip in cortical activation between the pretraining and posttraining tests, suggesting that the brains of brighter individuals streamline the processing of new information faster than those of their less intelligent counterparts do.

More here

No comments: