But comfort foods are so good...!

Learning about the HPA Axis and the way our body functions from stress-induced scenarios, you would think that stress-eating would not be a thing. The way our body handles stress,  stressful situations allow fight or flight reactions to come into motion which reduce digestion, reproduction and rest mechanisms, thus suppressing hunger when we are stressed. Instead, higher levels of respiration and cardiac events are a result to improve actions necessary to prevail whatever danger or threat there may be. But, with stress eating, the stress no longer stays at acute stress to where these adaptive mechanisms occur and provide positive outcomes, but chronic stress takes place. Too much stress for too long periods of times end up altering the stress systems, making it less adaptive and more of an issue.

Basically what happens is through this chronic activation of stress through the HPA axis, resistance to insulin and increased amounts of cortisol released both stimulate appetite which suppresses the signal for fullness of eating. This therefore is why people have the desire and need to eat even when they aren't hungry. In this, prolonged stress decreases the HPA axis activity and over time as the more calories are consumed from the increased appetite, more systems are shut down and less hormones released to prevent this from occurring in the first place. As everything shuts down and chronic stress continues, acute stress situations occur that overlay where a scenario that wouldn't have such an impact on hunger and digestion would take place is now affected due to the degeneration of the HPA axis, a greater preference and actual consumption of sugary and fatty foods occur in the end resulting in body fat gain (Yau, 2013).

Overall, acute stress doesn't cause hunger or stress eating, but an overlaying of chronic stress that occurs over a long period of time to affect the HPA axis in a negative way to when acute stress occurs on top of chronic stress, it isn't able to function in it's proper way and overeating takes place. So the next time you eat that cookie when you are stressed, now you know that you aren't actually hungry and you're experiencing chronic and acute stress simultaneously... hope that helps??


Reference:
Yau, Y. H., & Potenza, M. N. (2013). Stress and eating behaviors. Minerva endocrinologica, 38(3), 255–267.

Pinhole Surgical Technique: Stressed and regressed?

Within the past few decades, stress levels have increased significantly in the human population. We have shifted to an era where chronic diseases has dominantly overpowers infectious diseases that were the most common causes of death. Stress can disrupt homeostasis which could lead to a fluctuation of immune response levels. The direct association between periodontal disease (gum disease) and stress remains to be proven, however, recent studies indicate that stress is a risk indicator for the disease (Goyal et al., 2013).

Pinhole Surgical Technique (PST) is a form of  periodontal disease management that is new to treating marginal tissue recession (MTR). Invented and practiced since 2006, it has been growing in popularity over the past few years and is only available from a handful of prestigious and rigorously trained dentists (Reddy, 2017). I have the fortune of working under one of the few dentists in Colorado certified to perform this technique, and the privilege to assist on these procedures. PST entails taking existing gingiva to cover an exposed root surface using a 16-gauge hypodermic needle. The needle penetrates the alveolar mucosa and the periosteum apical of the recessed area, creating a “pinhole” in the gums through the mucosal and tissue layer and freeing muscular and fibrous adhesions (Beck, 2018). Instruments designed by Dr. John C. Chao DDS, specific to PST, are inserted through the pinhole, moving the mucogingival tissue until the tissue advances to the desired coronal position to cover the exposed root. The tissue is then stabilized by collagen membrane, positioned at interdental papillae until there is sufficient fullness to allow for tissue regeneration, sufficiently gum recession (Reddy, 2017). 

This technique makes for a minimally invasive procedure as it requires no other incisions besides the pinhole, no sutures, no scalpels, and no grafts, while providing immediate, visible results of root coverage. Not only is PST a minimally invasive technique with immediate visualized results and a 95% rate of high satisfaction, studies have demonstrated that PST results in fewer postoperative complications and quicker healing time. After an average of 4 days post-op, painkillers are discontinued; pain, swelling and bleeding is minimal, only presenting in an average of 30-35% of cases, and subsiding after 2-3 days (Reddy, 2017). The development of new techniques and procedures that not only improves the health care offered, but the quality of life experienced after, demonstrates the benefits of innovation and motivation to continue research. 

Beck , T. M. (2018). The Pinhole Surgical Technique: A Clinical Perspective and Treatment Considerations From a Periodontist. CDA Journal, 46(10), 647–651. Retrieved from https://pinholesurgicaltechnique.com/pdf/Beck-CDA-journal-Pinhole-article-October-2018.pdf

Chao, J. C. (2012). A Novel Approach to Root Coverage: The Pinhole Surgical Technique . The International Journal of Periodontal & Restorative Dentistry, 32(5), 521–530. Retrieved from https://pinholesurgicaltechnique.com/wp-content/uploads/2019/07/ChaoBrochure.pdf

Goyal, S., Gupta, G., Thomas, B., Bhat, K. M., & Bhat, G. S. (2013). Stress and periodontal disease: The link and logic!!. Industrial psychiatry journal, 22(1), 4–11. doi:10.4103/0972-6748.123585

Reddy S. (2017). Pinhole Surgical Technique for treatment of marginal tissue recession: A case series. Journal of Indian Society of Periodontology, 21(6), 507–511. doi:10.4103/jisp.jisp_138_17

Another Reason To Give Up Smoking

There is a known correlation between nicotine usage and type 2 diabetes (Bruschetta & Diano, 2019). However, it remains unclear how the two impact each other (Bruschetta & Diano, 2019). A recent study suggested that there is a link between the medial habenula brain region (mHb) and the pancreas that allows expression of genes in the brain to impact the pancreas and can result in an increase risk of diabetes in smokers (Bruschetta & Diano, 2019). The researches found this potential pathway by injecting a fluorescently labelled virus into the pancreas and monitoring where in traveled (Duncan et al., 2019). The virus travelled to several different areas of the brain, including the mHb (Duncan et al., 2019).
    Studies examining this area of the brain have suggested that elevated activity leads to depression, anxiety, and fear (Viswanath, Carter, Baldwin, Molfese, & Salas, 2014).  Additionally, the mHb has a high concentration of nicotine acetylcholine receptors (Viswanath at al., 2014). Specifically the α5 and β 4 subunits, which are necessary for nicotine-induced seizures and somatic symptoms of withdrawal (Viswanath at al., 2014).
    TCF7L2, a gene that has one of the largest effects on diabetes susceptibility, is also found to be expressed in the mHb (Huang, Liao, Huang, Chen, & Sun, 2018). TCF7L2 expression controls the transcription of glucagon-like peptide-1 hormone (GLP-1) (Huang et al., 2018). This hormone is crucial for glucose homeostasis and works by stimulating insulin secretion and inhibiting glucagon (Huang et al., 2018). The researches deleted the TCF7L2 gene in mice and provided a nicotine drip to observe the effects (Duncan et al., 2019). They found that the mutated mice were less likely to have nicotine-induced blood glucose increases (Duncan et al., 2019).
    When an individual smokes, the nicotine can bind to the nACh receptors on the mHb and result in greater expression of genes, including TCF7L2 (Duncan et al., 2019). This transcription factor is able to regulate GLP-1, causing high blood glucose concentrations and increasing the chance of diabetes (Duncan et al., 2019).

Bruschetta, G., & Diano, S. (2019). Brain-to-pancreas signalling axis links nicotine and diabetes. Nature, 574(7778), 336–337. https://doi.org/10.1038/d41586-019-02975-w
Duncan, A., Heyer, M. P., Ishikawa, M., Caligiuri, S. P. B., Liu, X., Chen, Z., … Kenny, P. J. (2019). Habenular TCF7L2 links nicotine addiction to diabetes. Nature, 574(7778), 372–377. https://doi.org/10.1038/s41586-019-1653-x
Huang, Z., Liao, Y., Huang, R., Chen, J., & Sun, H. (2018). Possible role of TCF7L2 in the pathogenesis of type 2 diabetes mellitus. Biotechnology & Biotechnological Equipment, 32(4), 830–834. https://doi.org/10.1080/13102818.2018.1438211
Nicotine addiction linked to diabetes through a DNA-regulating gene in animal models. (2019, October 16). Retrieved October 22, 2019, from National Institutes of Health (NIH) website: https://www.nih.gov/news-events/news-releases/nicotine-addiction-linked-diabetes-through-dna-regulating-gene-animal-models
Viswanath, H., Carter, A. Q., Baldwin, P. R., Molfese, D. L., & Salas, R. (2014). The medial habenula: Still neglected. Frontiers in Human Neuroscience, 7. https://doi.org/10.3389/fnhum.2013.00931

Sheep & Sexuality: Looking at Sexual Dimorphism in the Hypothalamus

The Sexually Dimorphic Nucleus (SDN), located in the preoptic area of the hypothalamus, was first identified in 1978 in rodents. This area of the brain is the most visible difference between male and female brains, such that it is nearly 2.2 times larger in volume in males than females (Hofman & Swaab, 1989).

In one of my labs, we were asked to identify and measure this structure in a sheep brain and compare our answers to other classmates in order to determine the gender of our animal. Students with female sheep brains had SDN measurements of 3-5 cm and others with males had measurements of 9-11 cm. We asked our instructor what would be concluded if the SDN was somewhere in the middle of those values, and they informed us that the SDN has been explored in a number of studies which found that an individual’s sexuality may be linked to the size of this structure.

I found an article published in 2004 looking specifically at the various sizes of male sheep SDN with consideration to their sexual preference. The researchers found that rams considered “female-oriented” (sexually active with females) had larger SDNs than “male-oriented” (sexually active with male rams (Roselli, Larkin, Resko, Stellflug & Stormshak, 2004). Female sheep have the smallest SDNs. The neurons that form this cell cluster express cytochrome p450 aromatase. It was found that female-oriented rams expressed more aromatase than male-oriented rams, who expressed intermediate levels. It is thought that this structure plays a role in the expression of sexual behaviors and possible estrogen synthesis. The rams classified as male-oriented did not behave like females or have any different social behaviors.

Further studies have been conducted on this topic in rodents and humans. These findings show a scientific association between brain structure and sexuality. The implications of these conclusions could have a positive impact on society’s understanding of sexual orientation. It provides a biological substrate for sexual orientation that could disprove any notion that homosexuality is a mental illness or a choice.

Hofman, M. A., & Swaab, D. F. (1989). The sexually dimorphic nucleus of the preoptic area in the human brain: a comparative morphometric study. Journal of anatomy, 164, 55–72.

Roselli, C. E., Larkin, K., Resko, J. A., Stellflug, J. N., & Stormshak, F. (2004). The Volume of a Sexually Dimorphic Nucleus in the Ovine Medial Preoptic Area/Anterior Hypothalamus Varies with Sexual Partner Preference. Endocrinology, 145(2), 478–483. https://doi.org/10.1210/en.2003-1098

Girls: This is why we're hot!!

Starting the new content and material in reproduction, females are not only incredibly complex beings emotionally, but also biologically. Specifically, their menstruation and ovulation cycle. Diving deeper from such an intrinsic mechanism occurring in the female body into more external aspects that result given their biology: attractiveness during ovulation. The big questions are: are women more attractive or appealing to the opposite sex during ovulation than in other stages of their cycle? And why or how could this be? 

Craig Roberts designed a study based on female facial attractiveness during the fertile phase of the menstrual cycle. Taking two pictures of the same women's face one during the follicular phase and the other during the luteal phase, with multiple different women for variety, allowed the study to be conducted by the voting of men and women on which they viewed to be the more attractive photo of that given women. The results concluded that although small, there was a difference in the votes of which face was more attractive, being the face that was in the follicular stage (Roberts, 2004).

Another study done by Kelly Gildersleevea, she tests the natural body odor and scent of women through the use of male participants and female subjects on whether or not their odor was different in separate stages of ovulation. The results were as she hypothesized: there were! And the men recorded to be more attracted to the high-fertility ovulating scent that a woman had in comparison to the low-fertility scent (Gildersleevea, 2011). 

Some rational and reasoning behind this could be due to evolutionary mechanisms that take place such as women preparing and attracting a man to mate and reproduce with which leads to an increase in her physical enticement to men through pupillary dilation, lip color and size, skin color and tone adjustments all through the increase of levels of estrogen during the follicular stages of the menstrual cycle. Of course more studies need to be done to research further into this occurrence and really narrow down what exactly is going on, what about the physical attraction makes a woman so appealing or what about her scent makes her more desirable. 

But, the overall message is clear and interesting- women, using your monthly cycle of pain can now be used as a monthly cycle of beauty… so bat those eyelashes and let the boys flock to you!

References:

A.Gildersleevea, K., G.Haseltona, M., M.Larsona, C., & G.Pillsworthb, E. (2011, November 23). Body odor attractiveness as a cue of impending ovulation in women: Evidence from a study using hormone-confirmed ovulation. Retrieved from https://www.sciencedirect.com/science/article/abs/pii/S0018506X11002704?via=ihub.

Roberts S.C., Havlicek J., Flegr J., Hruskova M., Little A. C., Jones B. C., Perrett D. I., and Petrie M. Female facial attractiveness increases during the fertile phase of the menstrual cycle 271 Proc. R. Soc. Lond. B http://doi.org/10/1098/rsbl.2004.0174

New Advice on Peanut Allergies: LEAPing to Conclusions?

            In April of this year, the American Academy of Pediatrics (AAP) recommended systematically feeding peanuts to at-risk (those with eczema, egg allergies, or both) infants as young as 4-6 months to prevent peanut allergy development (Wallis, 2019, August). Up through 2008, it was believed that peanuts should be avoided until a child turned 2 or 3 (Wallis, 2019, August).

The AAP’s advice is based on a 2015 study by the group Learning Early About Peanut Allergy (LEAP) (Du Toit et al., 2015). In the LEAP study, 640 at-risk infants were tested for peanut sensitivity via a skin prick. Children either had no reaction or a discernibly irritated patch of skin, and those with an excessive skin reaction were eliminated from the study (Du Toit et al., 2015). Next, children were randomly divided into one of two treatment categories: one category waited 60 months to be introduced to peanuts (the “avoidance group”), and the second had doses of peanuts incorporated systematically into their diets starting at 4-11 months of age (the “consumption group”) (Du Toit et al., 2015).

            Out of the 530 infants who had no reaction to the skin test at the start of the study, 13.7% of the avoidance group developed a peanut allergy while only 1.9% of the consumption group developed a peanut allergy (Du Toit et al., 2015). Out of the remaining 98 children who tested positive during the initial skin test, 35.3% of the avoidance group still had the allergy while only 10.6% of the consumption group still had the allergy (Du Toit et al., 2015). Both of these statistics had significant p-values, suggesting strong evidence for the ability of early peanut introduction to reduce the chance of or reverse peanut allergy development in high-risk infants (Du Toit et al., 2015). 

            The suspected physiology ongoing in the consumption group is that children develop peanut-specific IgG4 antibodies (known biomarkers of potential immune modulation) (Du Toit et al., 2015). Contrarily, children in the avoidance group developed higher IgE peanut-specific antibodies (known biomarkers of allergic responses) (Du Toit et al., 2015).

            Despite these findings, administering peanuts to younger children should be done with extreme caution. Rabinovitch et al. called out the LEAP study for not including a more diverse subject population (the participants were 70% white) and for not emphasizing the harmful consequences for the 1.9% of the negative skin test/consumption group that did still develop a peanut allergy (Rabinovitch, Shah, & Lanser, 2015). An African American high-risk infant with a negative skin test went into anaphylaxis while being monitored during his first peanut-dosing, but was luckily at the hospital and recovered (Rabinovitch et al., 2015). Regardless of whether this infant’s ethnicity was actually correlated to the anaphylaxis, in the context of justice and non-maleficence researchers should always use diverse groups in studies to effectively assess risks across different populations.

Cited Literature

Du Toit, G., Roberts, G., Sayre, P. H., Bahnson, H. T., Radulovic, S., Santos, A. F., . . . Team, L. S. (2015). Randomized trial of peanut consumption in infants at risk for peanut allergy. N Engl J Med, 372(9), 803-813. doi:10.1056/NEJMoa1414850

Rabinovitch, N., Shah, D., & Lanser, B. J. (2015). Look before you LEAP: Risk of anaphylaxis in high-risk infants with early introduction of peanut. J Allergy Clin Immunol, 136(3), 822. doi:10.1016/j.jaci.2015.07.002

Wallis, C. (2019, August). If you give a baby a peanut. Scientific American, 22.