25.07.2009

Кортинко улыбнуло

Весёленькая пикча. :) Отсюда - ianheath653.wordpress.com/category/humor/page/8/

22.07.2009

Немного о болевой чувствительности

Отличная заметка в блоге у http://scienceblogs.com/neurophilosophy/2009/07/swearing_increases_pain_tolerance.php

Category: NeurosciencePsychology
Posted on: July 13, 2009 1:02 PM, by Mo

SWEARING OCCURS IN most cultures - people swear to let off steam, or to shock or insult others. It is also a common response to a painful experience. We've all done it: after stubbing our toe, or hitting our thumb with a hammer, we draw a sharp breath and mutter a swear word. Until now, though, whether swearing actually alters our perception of pain had not been investigated. But according to a new study due to be published next month in the journal NeuroReport, swearing increases pain tolerance, enabling us to withstand at least one form of pain for longer.

Some pain theorists regard our tendency to swear after hurting ourselves to be a form of "pain-related catastrophising" - an exaggerated negative mind set which is brought to bear during a painful experience. As such, swearing is thought of as a maladaptive response, which contributes to the intensity of the pain and emotional distress. Given that it is such a common response, Richard Stephens and his colleagues at the Keele University School of Psychology set out test the hypothesis that swearing would decrease pain tolerance and increase pain perception.

They recruited 67 undergraduates, and asked to make two short lists of words - one containing five words they might use after hitting themselves on the thumb with a hammer, the other containing five words they might use to describe a table. The participants submerged one of their hands into room temperature water for three minutes, to provide a standardized starting point, then transferred it to a container of cold water and instructed to keep it submerged for as long as they could. In one condition, they were told to repeat the first swear word they had included in their list; in another, they repeated one of the words describing a table.

The researchers measured how long the participants kept their hands submerged in cold water, and asked them to rate the amount of pain they felt. Their heart rates were also recorded after they had submerged their hands in room temperature water as well as after the submersion in cold water. Contrary to their hypothesis, they found that swearing actually reduced the amount of pain felt. The participants kept their hands submerged in the cold water longer for longer, and also reported experiencing less pain, when they repeated a swear word than when they repeated a word describing a table. Swearing was also associated with increased heart rate.

Swearing therefore enabled the participants to tolerate to the cold temperature for longer, and also caused a reduction in their perception of the pain felt. A difference between males and females was observed. Swearing led to a greater reduction in pain perception and a bigger increase in heart rate in females. Most interestingly though, the effect of swearing in females occurred regardless of their tendency to catastrophise their pain. On the other hand, in the males, catastrophising was found to diminish the effects of swearing on the felt pain. This is interesting in light of other findings which show that men generally catastrophise less, but swear more often, than women.

This study shows that swearing appears to have an analgesic effect under certain conditions. Exactly how is unclear, but the authors suggest that it is because swearing induces negative emotions. It is well known that pain has a strong emotional aspect to it. Fear of pain, for example, is known to enhance pain perception, possibily by activating pathways which descend from the brain and modulate noxious stimuli entering the spinal cord. Swearing, too, is known to induce negative emotions (according to Steven Pinker, it taps into the "deep and ancient parts of the emotional brain"). It may therefore trigger a physiological alarm reaction known as the fight or flight response, which accelerates the heart rate and reduces sensitivity to pain.

14.07.2009

Клетки с повреждённой ДНК общаются между собой :)

Здорово! Читаю на http://www.biologynews.net/archives/2009/07/13/dnadamaged_cells_communicate_with_neighbors_to_let_them_know_theyre_in_trouble.html
When cells experiencing DNA damage fail to repair themselves, they send a signal to their neighbors letting them know they're in trouble. The discovery, which shows that a process dubbed the DDR (DNA Damage Response) also controls communication from cell to cell, has implications for both cancer and aging. The findings appear in the July 13 online edition of the Nature Cell Biology.
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When a cell experiences DNA damage, its first response is to try to repair the damage. If that doesn't work the cell, hopefully, either commits suicide or stops dividing, two intrinsic mechanisms for preventing cancer according to Judith Campisi, PhD, lead author of the study and a faculty member at the Buck Institute for Age Research. The discovery of the extracellular signaling mechanism, which sets off an inflammatory response, explains how unsuccessful DNA repair at the cellular level impacts tissues, which are the vital units of function in complex organisms like humans, she said.
"With regard to cancer, we found that if there is a mutant and potentially cancerous cell in the vicinity of the damaged cell, the signals from the damaged cell can encourage that mutant cell to behave more aggressively cancerous," said Campisi. "With regard to aging, we think the inflammatory signals from damaged cells propagate an aging 'field' whereby damage builds up over time, impacting not only the individual damaged cells, but the function of the tissue itself." When Buck scientists disabled particular proteins involved in the DDR, the cell-to-cell communication was cut off.
Buck Institute scientist Francis Rodier, PhD, led the team that did the research in the Campisi lab. He was surprised to find that even though the DDR signaling process was activated inside the cultured human cells within minutes of the DNA damage, it took 24 to 48 hours for the damaged cells to start secreting the inflammatory signals.
"We think the cell is giving itself time to repair its DNA before alerting the immune system that there's a problem," said Rodier. He added that scientists were also surprised to discover that the damage-induced communication signaling pathway bypasses a powerful tumor suppressor gene known as p53. That finding gives scientists a target to shut down the inflammatory process without hampering the activity of p53, which is essential to prevent cancer. It also explains why cancerous tumors are still able to secrete inflammatory signals when p53 has mutated and lost its tumor suppressing capabilities.
"Inflammation is a hallmark symptom of cancer," said Rodier. "Inflammation also promotes cancer, so this helps us begin to understand what's involved in that process."
The findings also help explain the aging process Campisi said. The immune system, which destroys damaged cells (such as skin cells whose DNA has been exposed to UV radiation), is not perfect, she said. "Damaged cells that survive the activity of the immune system are sending out continuous danger signals to surrounding cells. That constant alarm drives inflammation, which helps drive aging." Campisi added, "Now we have a target to focus on that could stop those damaged cells from sending out the inflammatory signals."
Source : Buck Institute for Age Research

06.07.2009

Регулярный секс и повреждения ДНК

Занятно! Читаю на http://www.biologynews.net/archives/2009/06/30/daily_sex_helps_to_reduce_sperm_dna_damage_and_improve_fertility.html

Daily sex (or ejaculating daily) for seven days improves men's sperm quality by reducing the amount of DNA damage, according to an Australian study presented today (Tuesday) to the 25th annual meeting of the European Society of Human Reproduction and Embryology in Amsterdam.

Until now there has been no evidence-based consensus amongst fertility specialists as to whether or not men should refrain from sex for a few days before attempting to conceive with their partner, either spontaneously or via assisted reproduction.

Dr David Greening, an obstetrician and gynaecologist with sub specialist training in reproductive endocrinology and infertility at Sydney IVF, Wollongong, Australia, said: "All that we knew was that intercourse on the day of ovulation offered the highest chance of pregnancy, but we did not know what was the best advice for the period leading up to ovulation or egg retrieval for IVF.

"I thought that frequent ejaculation might be a physiological mechanism to improve sperm DNA damage, while maintaining semen levels within the normal, fertile range."

To investigate this hypothesis, Dr Greening studied 118 men who had higher than normal sperm DNA damage as indicated by a DNA Fragmentation Index (DFI). Men who had a more than 15% of their sperm (DFI >15%) damaged were eligible for the trial. At Sydney IVF, sperm DNA damage is defined as less than 15% DFI for excellent quality sperm, 15-24% DFI for good, 25-29% DFI for fair and more than 29% DFI for poor quality; but other laboratories can have slightly different ranges.

The men were instructed to ejaculate daily for seven days, and no other treatment or lifestyle changes were suggested. Before they started, levels of DNA damage ranged between 15% and 98% DFI, with an average 34% DFI when measured after three days' abstinence. When the men's sperm was re-assessed on the seventh day, Dr Greening found that 96 men (81%) had an average 12% decrease in their sperm DNA damage, while 22 men (19%) and an average increase in damage of nearly 10%. The average for the whole group dropped to 26% DFI.

Dr Greening said: "Although the mean average was 26% which is in the 'fair' range for sperm quality, this included 18% of men whose sperm DNA damage increased as well as those whose DNA damage decreased. Amongst the men whose damage decreased, their average dropped by 12% to just under 23% DFI, which puts them in the 'good' range. Also, more men moved into the 'good' range and out of the 'poor' or 'fair' range. These changes were substantial and statistically highly significant.

"In addition, we found that although frequent ejaculation decreased semen volume and sperm concentrations, it did not compromise sperm motility and, in fact, this rose slightly but significantly.

"Further research is required to see whether the improvement in these men's sperm quality translates into better pregnancy rates, but other, previous studies have shown the relationship between sperm DNA damage and pregnancy rates.

"The optimal number of days of ejaculation might be more or less than seven days, but a week appears manageable and favourable. It seems safe to conclude that couples with relatively normal semen parameters should have sex daily for up to a week before the ovulation date. In the context of assisted reproduction, this simple treatment may assist in improving sperm quality and ultimately achieving a pregnancy. In addition, these results may mean that men play a greater role in infertility than previously suspected, and that ejaculatory frequency is important for improving sperm quality, especially as men age and during assisted reproduction cycles."

Dr Greening said he thought the reason why sperm quality improved with frequent ejaculation was because the sperm had a shorter exposure in the testicular ducts and epididymis to reactive oxygen species – very small molecules, high levels of which can damage cells. "The remainder of the men who had an increase in DFI might have a different explanation for their sperm DNA damage," he concluded.

Source : European Society for Human Reproduction and Embryology

Восстановление функций мозга после метамфетаминовой абстиненции

Интересно написано на http://www.biologynews.net/archives/2009/06/29/brain_functions_that_can_prevent_relapse_improve_after_a_year_of_methamphetamine_abstinence.html
Іn a study published online by the Journal of Substance Abuse Treatment, UC Davis researchers report that it takes at least a year for former methamphetamine users to regain impulse control. The results tell recovering substance abusers, their families and drug-treatment specialists that it can take an extended period of time for the brain functions critical to recovery to improve.

"Recovery from meth abuse does not happen overnight," said Ruth Salo, lead author of the study and a UC Davis assistant professor of psychiatry and behavioral sciences. "It may take a year — or even longer — for cognitive processes such as impulse control and attentional focus to improve. Treatment programs need to consider this when monitoring recovering addicts' progress during their early periods of abstinence."

Salo specializes in the behavioral, neuropsychiatric and cognitive outcomes of methamphetamine addiction — a particularly difficult condition to treat, primarily due to prolonged, intense cravings for the drug. During her career, she has worked with hundreds of methamphetamine addicts.

"All of them want to know if there is hope," Salo said. "We used to think most, if not all, effects of meth addiction were permanent. This study adds to the growing evidence that this assumption is not true. I can confidently tell patients that the longer they stay in a structured rehabilitation program and remain drug free, the more likely it is that they will recover some important brain functions."

For the current study, Salo used the widely-validated, computer-based Stroop attention test to measure the abilities of 65 recovering methamphetamine abusers to use cognitive control — or direct their attention to specific tasks while ignoring distractors. Study participants had been abstinent for a minimum of three weeks and a maximum of 10 years, and they had previously used the drug for periods ranging from 24 months to 28 years. The data for the 65 individuals were compared to Stroop attention test data from 33 participants who had never used methamphetamine.

"The test taps into something people do in everyday life: make choices in the face of conflicting impulses that can promote a strong but detrimental tendency," Salo explained. "For meth users, impairments in this decision-making ability might make them more likely to spend a paycheck on the immediate satisfaction of getting high rather than on the longer-term satisfaction gained by paying rent or buying groceries."

The study analyzed cognitive control in terms of the amount of time since methamphetamine was last used as well as total time spent using the drug. The researchers found that those who were recently abstinent (three weeks to six months) performed significantly worse on the Stroop test than those who had been abstinent one year or longer. In addition, there was no statistical difference between test results for those abstinent at least one year and non-drug using controls. Longer-term methamphetamine use was associated with worse test scores. Similarly, longer-term abstinence was connected to improved test performance.

According to Salo, the new study mirrors previous magnetic resonance imaging (MRI) studies she and her colleagues published in 2005 showing a partial normalization of chemicals in selected brain regions after one year of methamphetamine abstinence.

"Together, the studies provide strong evidence that, eventually, meth abusers in recovery may be able to make better decisions and regain the impulse control that was lost during their drug use period," she said.

Salo said that more research is needed to determine just how the brain recovers from methamphetamine addiction and if behavioral treatments can hasten that recovery. She plans to continue neuroimaging studies to further define the brain functions affected by the drug. Her ultimate goal is to provide information essential to refining treatment programs for this population of drug users.

"Meth use worldwide is pandemic," she said, referring to the estimated 35 million people who have used the neurotoxic stimulant or similar drugs. "Recovery is difficult, but possible. The point of my research is to better understand the neural and behavioral consequences of this toxic drug along with the brain and behavior changes that are possible with long-term abstinence."

Source : University of California - Davis - Health System