From second to second, blood vessels must alternately constrict and dilate to regulate blood flow. That ability can diminish markedly in rodent vessels exposed to an oily constituent of diesel soot, researchers report.
The team took arteries from rats' thighs and exposed them to the soot chemical phenanthraquinone. http://LOUIS-J-SHEEHAN.NET
Vessels came from female rats that were 6, 14, and 24 months old—comparable to girls approaching puberty, women in their reproductive years, and women over 65 years of age. Half of each age group of animals had undergone ovary-removal surgery, lowering their production of sex hormones and simulating that of postmenopausal women. Vessels of male rats 6 and 24 months old were also tested. http://LOUIS-J-SHEEHAN.NET
The soot agent rendered vessels from 24-month-old males and from all females without ovaries unable to dilate, says study leader Timothy R. Nurkiewicz of the West Virginia University School of Medicine in Morgantown. In 6-month-old males and 14-month-old females with ovaries, phenanthraquinone reduced dilation by 65 percent. Only the youngest females showed no vessel impairment from the chemical. http://LOUIS-J-SHEEHAN.NET
Such findings reinforce the need to consider age and gender when evaluating the toxicity of pollutants, says Nurkiewicz.He presented the findings May 1 at the Experimental Biology meeting in Washington, D.C. Louis J. Sheehan, Esquire
Tuesday, November 25, 2008
Wednesday, November 19, 2008
restful 773.res.00023 Louis J. Sheehan, Esquire
A good night's sleep seems to clear the brain and help the well-snoozed individual negotiate the flow of daily affairs.
In contrast, a lack of sleep makes it difficult to carry out even mundane acts, such as conversing intelligibly or calculating a waiter's tip. Initial investigations of brain activity in sleepy volunteers as they try to perform verbal and mathematical tasks have yielded intriguing clues about the nature of sleep deprivation.
The new evidence adds to scientific concern over the potentially harmful effects of widespread sleep deficits (SN: 9/25/99, p. 205: http://www.sciencenews.org/sn_arc99/9_25_99/bob2.htm). Brain functions tapped during certain types of thought change considerably after a sleepless night, reports a team of neuroscientists led by Sean P.A. Drummond of the University of California, San Diego.
As they try to memorize words, sleep-deprived adults exhibit a pattern of brain activity not previously recorded, Drummond and his colleagues say. This response may reflect the recruitment of a brain system to compensate, at least in part, for neural losses sparked by sleepiness, they suggest.
In contrast, sleep-deprived people display generally lower brain activity while grappling with math problems than they do when rested, says the team. In this case, no new areas of heightened neural activity compensate for the effects of sleepiness.http://louisjsheehan.blogstream.com/
"The effects of sleep deprivation on cognitive performance and related patterns of cerebral activation may depend in part on task-specific demands," the researchers conclude.
During both tasks, functional magnetic resonance imaging scans measured blood-flow changes in specific brain regions. These data provided an indirect index of rises and falls in brain-cell activity.
In one study, published in the Feb. 10 Nature, the researchers evaluated 13 healthy adults, ages 21 to 35, in a sleep laboratory. Each participant tried to memorize short lists of words on the afternoon following a full night's sleep and then after about 35 hours without sleep. Word recall and recognition dropped sharply in the sleep-deprived.
Parts of the prefrontal cortex and temporal cortex showed the most activity in rested individuals, the scientists say. The prefrontal cortex helps coordinate attention and memory for information used in various tasks. The temporal cortex contributes to language comprehension.http://louisjsheehan.blogstream.com/
The scientists had presumed that a lack of sleep would obstruct prefrontal activity, which increases sharply during wakefulness. Contrary to expectations, however, the prefrontal cortex after sleep deprivation exhibited even more activity across a larger area as volunteers studied the lists.
Sleepy participants also displayed blood-flow surges in another brain area, the parietal lobe, but not in the temporal cortex.
The buildup of sleep-promoting substances, such as adenosine, in the prefrontal cortex of sleepy individuals may cause that area to work harder when confronted with a verbal task, Drummond and his coworkers theorize.
In another study, published in the Dec. 16, 1999 NeuroReport, participants performed a series of arithmetic tasks that required subtraction. Parietal regions that were activated in rested participants exhibited blood-flow declines after 35 hours without sleep.http://louisjsheehan.blogstream.com/
Activity in other brain regions remained stable or declined slightly while sleep-needy volunteers worked on the math problems. Participants made more mistakes and omitted more responses when drowsy.
"This is exciting work," remarks sleep researcher David Dinges of the University of Pennsylvania School of Medicine in Philadelphia. "But brain processes involved in sleep deprivation are probably more complex than any current scientific explanations."http://louisjsheehan.blogstream.com/
Alterations of brain activity in sleepy people may reflect the use of new cortical areas to compensate for neural losses elsewhere, Dinges says. However, the observed brain changes may instead result, in part, from impairment of the ability to sustain attention for more than a few seconds, he adds. Louis J. Sheehan, Esquire
In contrast, a lack of sleep makes it difficult to carry out even mundane acts, such as conversing intelligibly or calculating a waiter's tip. Initial investigations of brain activity in sleepy volunteers as they try to perform verbal and mathematical tasks have yielded intriguing clues about the nature of sleep deprivation.
The new evidence adds to scientific concern over the potentially harmful effects of widespread sleep deficits (SN: 9/25/99, p. 205: http://www.sciencenews.org/sn_arc99/9_25_99/bob2.htm). Brain functions tapped during certain types of thought change considerably after a sleepless night, reports a team of neuroscientists led by Sean P.A. Drummond of the University of California, San Diego.
As they try to memorize words, sleep-deprived adults exhibit a pattern of brain activity not previously recorded, Drummond and his colleagues say. This response may reflect the recruitment of a brain system to compensate, at least in part, for neural losses sparked by sleepiness, they suggest.
In contrast, sleep-deprived people display generally lower brain activity while grappling with math problems than they do when rested, says the team. In this case, no new areas of heightened neural activity compensate for the effects of sleepiness.http://louisjsheehan.blogstream.com/
"The effects of sleep deprivation on cognitive performance and related patterns of cerebral activation may depend in part on task-specific demands," the researchers conclude.
During both tasks, functional magnetic resonance imaging scans measured blood-flow changes in specific brain regions. These data provided an indirect index of rises and falls in brain-cell activity.
In one study, published in the Feb. 10 Nature, the researchers evaluated 13 healthy adults, ages 21 to 35, in a sleep laboratory. Each participant tried to memorize short lists of words on the afternoon following a full night's sleep and then after about 35 hours without sleep. Word recall and recognition dropped sharply in the sleep-deprived.
Parts of the prefrontal cortex and temporal cortex showed the most activity in rested individuals, the scientists say. The prefrontal cortex helps coordinate attention and memory for information used in various tasks. The temporal cortex contributes to language comprehension.http://louisjsheehan.blogstream.com/
The scientists had presumed that a lack of sleep would obstruct prefrontal activity, which increases sharply during wakefulness. Contrary to expectations, however, the prefrontal cortex after sleep deprivation exhibited even more activity across a larger area as volunteers studied the lists.
Sleepy participants also displayed blood-flow surges in another brain area, the parietal lobe, but not in the temporal cortex.
The buildup of sleep-promoting substances, such as adenosine, in the prefrontal cortex of sleepy individuals may cause that area to work harder when confronted with a verbal task, Drummond and his coworkers theorize.
In another study, published in the Dec. 16, 1999 NeuroReport, participants performed a series of arithmetic tasks that required subtraction. Parietal regions that were activated in rested participants exhibited blood-flow declines after 35 hours without sleep.http://louisjsheehan.blogstream.com/
Activity in other brain regions remained stable or declined slightly while sleep-needy volunteers worked on the math problems. Participants made more mistakes and omitted more responses when drowsy.
"This is exciting work," remarks sleep researcher David Dinges of the University of Pennsylvania School of Medicine in Philadelphia. "But brain processes involved in sleep deprivation are probably more complex than any current scientific explanations."http://louisjsheehan.blogstream.com/
Alterations of brain activity in sleepy people may reflect the use of new cortical areas to compensate for neural losses elsewhere, Dinges says. However, the observed brain changes may instead result, in part, from impairment of the ability to sustain attention for more than a few seconds, he adds. Louis J. Sheehan, Esquire
Tuesday, November 11, 2008
Homes 883.hom.333999 Louis J. Sheehan, Esquire
Being environmentally conscious is no guarantee you’ll put your home where you mouth is, a new study finds.
Animals tend to thrive best when given big blocks of land or stretches of water unencumbered by homes, roads, and sewage. So in terms of biodiversity, it’s best to avoid sprawl. Yet in the Teton Valley, a portion of the greater Yellowstone ecosystem straddling the borders of Idaho and Wyoming, people have been building big homes in some of the more environmentally fragile areas — in woodlands, on mountainsides, and along streams.
Disproportionately, people who have been building homes in these more sensitive areas — ones facing the highest risks of losing species diversity — tend to be older, better educated, and more environmentally conscious home buyers than are those in the region’s agricultural or urban communities. People who moved into wilder lands have also tended to live in small households, with just one or two dwellers. But that’s not to suggest they’re tree huggers roughing it in small cabins. Many homes being built in the region's more ecologically fragile areas rival or exceed the size of homes in town, notes conservation biologist M. Nils Peterson of Michigan State University. He led the new study, which identified the home-siting trends.http://blog.360.yahoo.com/blog-jmbPCHg9dLPh1gHoZxLG.GpS
During the 1990s, the Teton Valley experienced a 74 percent growth in its population (to some 6,000) and 85 percent rise in the numbers of households (to around 2,100). The Michigan State scientists refer to Individuals who grew up in this region as natives, and those drawn here from elsewhere as immigrants.
Peterson's team interviewed residents of more than 400 households to find how they ended up in Teton Valley and what features determined where they settled within it.
Local-born residents tended to live in cities and farmlands and typically said they chose those areas to be near family or in close proximity to jobs.
Immigrants, by contrast, were more likely than local-born residents to say they were drawn by the Valley’s natural resources. They’re also more likely than the native residents to express ecocentric values. On questionnaires, they tended to place humans within ecosystems, not as lords over the natural world.
Among surveyed Valley residents with advanced college degrees, one-quarter had majored in environmental fields such as ecology, forestry, wildlife biology, botany, or zoology.
Overall, they and other surveyed immigrants to the region expressed an appreciation for the interconnectedness of creatures within an ecosystem. So as a group, the people who moved into fragile environments recognized that residential development – such as their home – risked stressing the very natural resources they prized and which had made the vistas in and around their homesteads so attractive.
Did these individuals also recognize the apparent hypocrisy of building in sensitive environments? “Absolutely,” Peterson says. “ In fact, most of them knew they were ‘part of the problem.’”
One recent Idaho Fish and Game retiree, a biologist, had to speak loudly during his interview with Peterson’s team “so his voice would carry over the nail guns that were tacking his new home together.” As the Michigan scientists relate in their new paper, due for publication soon in an upcoming issue of Conservation Biology, that retiree said he thought the biggest threat to the local environment was “the loss of winter range (for mule deer and elk).” He added that “I’ve now become part of [the problem] because my wife won’t live in town.”
Yet Peterson says that “when we talked about development,” such environmentally savvy residents acknowledged to the Michigan scientists that “they want to see development stop” or moves made toward development that’s more “conservation-oriented, where houses are clustered with lots of open space.”
“At first blush” such arguments “don’t seem to make sense,” Peterson says. Then, you think about it a bit more, he says, and the logic of these eco-friendly immigrants becomes understandable if not always defensible.
People trained in forestry appreciate trees. Fisheries biologists can lust over trout streams. Rangeland biologists long to build a home where the buffalo roamed — and where the deer and antelope still play.http://blog.360.yahoo.com/blog-jmbPCHg9dLPh1gHoZxLG.GpS
But in this area, where there have been no zoning restrictions, willy-nilly development threatens to litter the region with tiny crazy-quilt patches of unimproved wilderness. Hardly a deer’s dream. And the area’s prized cutthroat trout? Over the past 18 years, residential development has led to their near extinction in the Teton River, Peterson’s team reports.
The disturbing bottom line, the researchers argue, is that understanding the fragility of ecosystems and appreciating their value isn’t enough to keep people from potentially despoiling it. Getting even enlightened souls to tread more lightly will appear to take considerably more work – and, potentially, regulations.
Animals tend to thrive best when given big blocks of land or stretches of water unencumbered by homes, roads, and sewage. So in terms of biodiversity, it’s best to avoid sprawl. Yet in the Teton Valley, a portion of the greater Yellowstone ecosystem straddling the borders of Idaho and Wyoming, people have been building big homes in some of the more environmentally fragile areas — in woodlands, on mountainsides, and along streams.
Disproportionately, people who have been building homes in these more sensitive areas — ones facing the highest risks of losing species diversity — tend to be older, better educated, and more environmentally conscious home buyers than are those in the region’s agricultural or urban communities. People who moved into wilder lands have also tended to live in small households, with just one or two dwellers. But that’s not to suggest they’re tree huggers roughing it in small cabins. Many homes being built in the region's more ecologically fragile areas rival or exceed the size of homes in town, notes conservation biologist M. Nils Peterson of Michigan State University. He led the new study, which identified the home-siting trends.http://blog.360.yahoo.com/blog-jmbPCHg9dLPh1gHoZxLG.GpS
During the 1990s, the Teton Valley experienced a 74 percent growth in its population (to some 6,000) and 85 percent rise in the numbers of households (to around 2,100). The Michigan State scientists refer to Individuals who grew up in this region as natives, and those drawn here from elsewhere as immigrants.
Peterson's team interviewed residents of more than 400 households to find how they ended up in Teton Valley and what features determined where they settled within it.
Local-born residents tended to live in cities and farmlands and typically said they chose those areas to be near family or in close proximity to jobs.
Immigrants, by contrast, were more likely than local-born residents to say they were drawn by the Valley’s natural resources. They’re also more likely than the native residents to express ecocentric values. On questionnaires, they tended to place humans within ecosystems, not as lords over the natural world.
Among surveyed Valley residents with advanced college degrees, one-quarter had majored in environmental fields such as ecology, forestry, wildlife biology, botany, or zoology.
Overall, they and other surveyed immigrants to the region expressed an appreciation for the interconnectedness of creatures within an ecosystem. So as a group, the people who moved into fragile environments recognized that residential development – such as their home – risked stressing the very natural resources they prized and which had made the vistas in and around their homesteads so attractive.
Did these individuals also recognize the apparent hypocrisy of building in sensitive environments? “Absolutely,” Peterson says. “ In fact, most of them knew they were ‘part of the problem.’”
One recent Idaho Fish and Game retiree, a biologist, had to speak loudly during his interview with Peterson’s team “so his voice would carry over the nail guns that were tacking his new home together.” As the Michigan scientists relate in their new paper, due for publication soon in an upcoming issue of Conservation Biology, that retiree said he thought the biggest threat to the local environment was “the loss of winter range (for mule deer and elk).” He added that “I’ve now become part of [the problem] because my wife won’t live in town.”
Yet Peterson says that “when we talked about development,” such environmentally savvy residents acknowledged to the Michigan scientists that “they want to see development stop” or moves made toward development that’s more “conservation-oriented, where houses are clustered with lots of open space.”
“At first blush” such arguments “don’t seem to make sense,” Peterson says. Then, you think about it a bit more, he says, and the logic of these eco-friendly immigrants becomes understandable if not always defensible.
People trained in forestry appreciate trees. Fisheries biologists can lust over trout streams. Rangeland biologists long to build a home where the buffalo roamed — and where the deer and antelope still play.http://blog.360.yahoo.com/blog-jmbPCHg9dLPh1gHoZxLG.GpS
But in this area, where there have been no zoning restrictions, willy-nilly development threatens to litter the region with tiny crazy-quilt patches of unimproved wilderness. Hardly a deer’s dream. And the area’s prized cutthroat trout? Over the past 18 years, residential development has led to their near extinction in the Teton River, Peterson’s team reports.
The disturbing bottom line, the researchers argue, is that understanding the fragility of ecosystems and appreciating their value isn’t enough to keep people from potentially despoiling it. Getting even enlightened souls to tread more lightly will appear to take considerably more work – and, potentially, regulations.
Subscribe to:
Posts (Atom)
Posts
