Search Immortality Topics:

Page 8,519«..1020..8,5178,5188,5198,520

Brain imaging studies of appetite in the context of obesity and the menstrual cycle

Posted: April 6, 2010 at 8:15 am

BACKGROUND

Obesity affects many aspects of health, including reproduction. Despite unrelenting warnings about the health consequences of obesity, its prevalence continues to rise. Beginning with the discovery of leptin in 1994, the endocrinology of energy homeostasis has been significantly advanced. More recently, brain imaging studies have been providing novel insights into homeostatic and hedonic aspects of human ingestive behavior.

METHODS

A comprehensive MEDLINE search was conducted on the topic of neuroendocrine control of ingestive behavior with an emphasis on functional magnetic resonance imaging studies. Additional articles were collected by hand searching the bibliographies of all relevant articles retrieved.

RESULTS

This review describes recent advances in our understanding of endocrine signals that respond to acute and chronic energy states and regulate ingestive behavior so as to achieve a balance between energy intake and energy expenditure. Recently published brain imaging studies, describing the neural networks that process endocrine signals of energy state and hedonic cues associated with highly palatable foods, are highlighted. Brain responses to food cues are described in the context of appetite changes during the menstrual cycle both in normal physiology and under the conditions anorexia nervosa and bulimia nervosa.

CONCLUSIONS

The prevalence of obesity belies the plethora of endocrine signals in place to ensure energy homeostasis. However, satiety signals appear to be counteracted by hedonic signals derived from highly palatable foods typical of today’s diet. A better understanding of the interaction between homeostatic and hedonic signals is needed to devise effective strategies for dealing with obesity. Menstrual cycle dependent changes in brain responses to food cues may provide insight into the normal physiological control of ingestive behavior as well as dysfunctional regulation associated with disordered eating.

Recommendation and review posted by G. Smith

The impact of body mass index on semen parameters and reproductive hormones in human males: a systematic review with meta-analysis

Posted: April 6, 2010 at 8:15 am

BACKGROUND

It has been suggested that body mass index (BMI), especially obesity, is associated with subfertility in men. Semen parameters are central to male fertility and reproductive hormones also play a role in spermatogenesis. This review aimed to investigate the association of BMI with semen parameters and reproductive hormones in men of reproductive age.

METHODS

MEDLINE, EMBASE, Biological Abstracts, PsycINFO and CINAHL databases and references from relevant articles were searched in January and February 2009. Outcomes included for semen parameters were sperm concentration, total sperm count, semen volume, motility and morphology. Reproductive hormones included were testosterone, free testosterone, estradiol, FSH, LH, inhibin B and sex hormone binding globulin (SHBG). A meta-analysis was conducted to investigate sperm concentration and total sperm count.

RESULTS

In total, 31 studies were included. Five studies were suitable for pooling and the meta-analysis found no evidence for a relationship between BMI and sperm concentration or total sperm count. Overall review of all studies similarly revealed little evidence for a relationship with semen parameters and increased BMI. There was strong evidence of a negative relationship for testosterone, SHBG and free testosterone with increased BMI.

CONCLUSIONS

This systematic review with meta-analysis has not found evidence of an association between increased BMI and semen parameters. The main limitation of this review is that data from most studies could not be aggregated for meta-analysis. Population-based studies with larger sample sizes and longitudinal studies are required.

Recommendation and review posted by G. Smith

Options for fertility preservation in prepubertal boys

Posted: April 6, 2010 at 8:15 am

BACKGROUND

Fertility in adult life may be severely impaired by gonadotoxic therapies. For young boys who do not yet produce spermatozoa, cryopreservation of immature testicular tissue (ITT) is an option to preserve their fertility, albeit still experimental. This paper covers current options for ITT cryopreservation and fertility restoration.

METHODS

Relevant studies were identified by an extensive Medline search of English and French language articles. Search terms were: gonadotoxicity, cytoprotection, cryopreservation, ITT, spermatogonia, testicular transplantation, testicular grafting and in vitro maturation (IVM).

RESULTS

Although no effective gonadoprotective drug is yet available for in vivo spermatogonial stem cell protection in humans, current evidence supports the feasibility of ITT cryopreservation before gonadotoxic treatment with a view to fertility preservation. Controlled slow freezing with dimethyl sulfoxide allows survival and proliferation of human spermatogonia after xenotransplantation, but only partial differentiation. Animal data look promising, since healthy offsprings have been obtained after transplantation of frozen testicular cell suspensions or tissue pieces. However, none of the fertility restoration options from frozen tissue, i.e. cell suspension transplantation, tissue grafting and IVM have proved efficient and safe in humans as yet.

CONCLUSION

While additional evidence is required to define optimal conditions for ITT cryopreservation with a view to transplantation or IVM, the putative indications for such techniques, as well as their limitations according to disease, are outlined.

Recommendation and review posted by G. Smith

Stuntkid: Anatomically Correct

Posted: April 5, 2010 at 11:01 pm

Anatomical Asphyxia

Anatomical Asphyxia

Anatomical Apnea

Anatomical Apnea

Anatomical Scar

Anatomical Scar

Jason Levesque labels himself as a Drawler, Designer, and Do’er of stunts, hence the name, Stuntkid.  Jason draws his main subject matter, women, with a light and delicate, yet edgy style, which is reflected well in his “Anatomically Correct” series above.  Love the ghosted skeleton beneath these women, makes them look as if they’re made of glass.

Also take a look through his photography, which is just as intriguing as his illustrations!

[spotted by Danielle Nadia Simm]

Recommendation and review posted by G. Smith

Serotonin Blocker May Build New Bone in Osteoporotic Mice by Decreasing GI Serotonin Levels

Posted: April 5, 2010 at 8:17 am

From WebMD:

When investigators treated mice with an experimental drug that stopped the gut from synthesizing serotonin, they were able to reverse severe bone loss and essentially cure osteoporosis in the animals.

Serotonin May Hold Key to Halting Osteoporosis. NatureVideoChannel — February 05, 2010 — A drug that reverses osteoporosis in mice looks like a promising candidate for treating the human version of the disease. Gerard Karsenty and his colleagues at Columbia University Medical Center have shown that blocking the neurotransmitter serotonin–secreted from the gut–promotes bone growth. The research appears on-line at http://www.nature.com/naturemedicine – Yadav et al. Nature Medicine, 7 February 2010. DOI: 10.1038/nm.2098.

Most bone treatments work to block bone loss and make existing bone stronger. One drug, Forteo (teriparatide), does build new bone, but it requires daily injections and is limited to two years of use.

References:
Serotonin May Be a Key to Treat Osteoporosis. WebMD.

Posted at Clinical Cases and Images. Stay updated and subscribe, follow on Twitter and Buzz, and connect on Facebook.


Recommendation and review posted by G. Smith

La Cabeza Circuitoide

Posted: April 5, 2010 at 8:17 am

Santi Pozzi

Circuit Head poster design by Santi Pozzi.  Meeeee gusta.

Recommendation and review posted by G. Smith


Page 8,519«..1020..8,5178,5188,5198,520