While the study is extremely interesting, it is important not to over-interpret the results. The authors suggest that there is a connection between prostate cancer and masturbation. But they do NOT prove that masturbation actually causes or protects against prostate cancer. It is quite possible that the level of hormones in a given man may determine both his frequency of masturbation and his chance of getting prostate cancer.
"...
"Frequent masturbation during men's 20s and 30s increased their risk of prostate cancer," Dimitropoulou tells WebMD. "But men in their 50s who masturbated frequently had decreased risk."
Of course, masturbation frequency is relative.
For men in their 20s, "frequent masturbation" was two to seven times per week. Compared to same-age men who reported masturbating less than once per month, 20-something frequent masturbators had a 79% higher risk of prostate cancer by age 60.
For men in their 50s, "frequent masturbation" was one or more times per week. Compared to same-age men who reported never masturbating, 50-something frequent masturbators had a 70% lower risk of prostate cancer...."
"...Meanwhile, Dimitropoulou, now at England's University of Cambridge, advises moderation for both younger and older men.
"It is kind of logical that a moderate level of masturbatory activity has to be maintained," she says. "Not too much, and not none at all.""
http://www.webmd.com/prostate-cancer/news/20090127/masturbation-and-prostate-cancer-risk
Sexual activity and prostate cancer risk in men diagnosed at a younger age.
Dimitropoulou P, Lophatananon A, Easton D, Pocock R, Dearnaley DP, Guy M, Edwards S, O'Brien L, Hall A, Wilkinson R, Eeles R, Muir KR; UK Genetic Prostate Cancer Study Collaborators; British Association of Urological Surgeons Section of Oncology.
Abstract
OBJECTIVE: To examine, in a case-control study, the association between the frequency of sexual activity (intercourse, masturbation, overall) and prostate cancer risk in younger men diagnosed at < or = 60 years old.
PATIENTS, SUBJECTS AND METHODS: In all, 431 prostate cancer cases and 409 controls participated and provided information on their sexual activity. In particular, the frequencies of intercourse and masturbation during the participants' different age decades (20s, 30s, 40s, 50s) were collected.
RESULTS: Whereas frequent overall sexual activity in younger life (20s) increased the disease risk, it appeared to be protective against the disease when older (50s). Alone, frequent masturbation activity was a marker for increased risk in the 20s and 30s but appeared to be associated with a decreased risk in the 50s, while intercourse activity alone was not associated with the disease.
CONCLUSION: These findings could imply different mechanisms by which sexual activity is involved in the aetiology of prostate cancer at different ages. Alternatively, there is a possibility of reverse causation in explaining part of the protective effect seen for men in their 50s
Monday, September 27, 2010
Sunday, September 26, 2010
Contagious Cancer
The common wisdom is that one can't "catch" cancer from another person. While this may be true for most cancers there are probably exceptions. One interesting case involves a type of cancer in dogs called Sticker's sarcoma. This cancer spreads from dog to dog during sex and when dogs byte or lick each other.
One fascinating point from the discovery published in the journal Cell is that the tumor is probably hundreds of years old (compare to the everage dog lifespan of 13 years)! The tumor is essentially immortal as it jumps from one animal to another.
"Robert A. Weinberg, a pioneer in the genetic underpinnings of cancer at the Whitehead Institute for Biomedical Research in Cambridge, Mass., said he was not surprised to learn that genetic studies had confirmed that Sticker's is a transmissible cancer, given the strength of earlier clues. But he agreed that the phenomenon raises difficult questions about why more cancers do not spread this way."
http://www.washingtonpost.com/wp-dyn/content/article/2006/08/10/AR2006081001535.html
Cell. 2006 Aug 11;126(3):477-87.
Clonal origin and evolution of a transmissible cancer.
Murgia C, Pritchard JK, Kim SY, Fassati A, Weiss RA.
MRC/UCL Centre for Medical Molecular Virology, Division of Infection and Immunity, University College London, 46 Cleveland Street, London W1T 4JF, UK.
Abstract
The transmissible agent causing canine transmissible venereal tumor (CTVT) is thought to be the tumor cell itself. To test this hypothesis, we analyzed genetic markers including major histocompatibility (MHC) genes, microsatellites, and mitochondrial DNA (mtDNA) in naturally occurring tumors and matched blood samples. In each case, the tumor is genetically distinct from its host. Moreover, tumors collected from 40 dogs in 5 continents are derived from a single neoplastic clone that has diverged into two subclades. Phylogenetic analyses indicate that CTVT most likely originated from a wolf or an East Asian breed of dog between 200 and 2500 years ago. Although CTVT is highly aneuploid, it has a remarkably stable genotype. During progressive growth, CTVT downmodulates MHC antigen expression. Our findings have implications for understanding genome instability in cancer, natural transplantation of allografts, and the capacity of a somatic cell to evolve into a transmissible parasite.
One fascinating point from the discovery published in the journal Cell is that the tumor is probably hundreds of years old (compare to the everage dog lifespan of 13 years)! The tumor is essentially immortal as it jumps from one animal to another.
"Robert A. Weinberg, a pioneer in the genetic underpinnings of cancer at the Whitehead Institute for Biomedical Research in Cambridge, Mass., said he was not surprised to learn that genetic studies had confirmed that Sticker's is a transmissible cancer, given the strength of earlier clues. But he agreed that the phenomenon raises difficult questions about why more cancers do not spread this way."
http://www.washingtonpost.com/wp-dyn/content/article/2006/08/10/AR2006081001535.html
Cell. 2006 Aug 11;126(3):477-87.
Clonal origin and evolution of a transmissible cancer.
Murgia C, Pritchard JK, Kim SY, Fassati A, Weiss RA.
MRC/UCL Centre for Medical Molecular Virology, Division of Infection and Immunity, University College London, 46 Cleveland Street, London W1T 4JF, UK.
Abstract
The transmissible agent causing canine transmissible venereal tumor (CTVT) is thought to be the tumor cell itself. To test this hypothesis, we analyzed genetic markers including major histocompatibility (MHC) genes, microsatellites, and mitochondrial DNA (mtDNA) in naturally occurring tumors and matched blood samples. In each case, the tumor is genetically distinct from its host. Moreover, tumors collected from 40 dogs in 5 continents are derived from a single neoplastic clone that has diverged into two subclades. Phylogenetic analyses indicate that CTVT most likely originated from a wolf or an East Asian breed of dog between 200 and 2500 years ago. Although CTVT is highly aneuploid, it has a remarkably stable genotype. During progressive growth, CTVT downmodulates MHC antigen expression. Our findings have implications for understanding genome instability in cancer, natural transplantation of allografts, and the capacity of a somatic cell to evolve into a transmissible parasite.
Sleep and Learning
One function of sleep is to help you learn. Scientists have found that sleep helps secure memories and improves certain types of learning. Therefore, to learn more one needs to sleep more.
"...a nap with REM (or “dream”) sleep improves people’s ability to integrate unassociated information for creative problem solving, and study after study has shown that sleep boosts memory. If you memorize a list of words and then take a nap, you’ll remember more words than you would without sleeping first. Even micronaps of six minutes—not including the time it takes to fall asleep, which is about five minutes if you’re really tired—make a difference."
http://hbr.org/web/2009/health/simplest-way-to-reboot-your-brain
"...a nap with REM (or “dream”) sleep improves people’s ability to integrate unassociated information for creative problem solving, and study after study has shown that sleep boosts memory. If you memorize a list of words and then take a nap, you’ll remember more words than you would without sleeping first. Even micronaps of six minutes—not including the time it takes to fall asleep, which is about five minutes if you’re really tired—make a difference."
http://hbr.org/web/2009/health/simplest-way-to-reboot-your-brain
Saturday, September 25, 2010
Interesting Testosterone Topics
Testosterone is an important hormone for both males and females. As testosterone level changes with age and for other reasons, it may have profound influence on the quality of adult life.
I find several effects of testosterone interesting and will blog about them:
Mental and physical energy
Maintenance of muscle tropism
Effects on prostate cancer
Cardiovascular health
Immune system
Fight-or-flight response
Falling in love
Risk-taking decisions
Fatherhood
I find several effects of testosterone interesting and will blog about them:
Mental and physical energy
Maintenance of muscle tropism
Effects on prostate cancer
Cardiovascular health
Immune system
Fight-or-flight response
Falling in love
Risk-taking decisions
Fatherhood
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