Obesity - symptom of a viral infection?

Type the search terms "obesity, adenovirus-36" into PubMed, the U.S. National Library of Medicine's online database of biomedical research, and you get 21 hits. In fact, the first report of a link between adenovirus infection and increased body fat was published in 2000 by Dhurandar et al¹. This report not only showed that infection with adenovirus-36 increased body fat, but also highlighted the fact that cholesterol and triglycerides were decreased in animals infected with adenovirus-36.

By 2004 this research group had shown that neutralizing antibodies to adenovirus-36 are associated with obesity in humans and showed that infection with the virus seemesto enhance differentiation of pre-adipocytes² (i.e. encouraged the formation of fat cells).

In 2007 Durhandar and co-workers showed that infection with adenovirus-36 not only enhanced differentiation of fat cells, but also decreased leptin levels and increased glucose uptake by fat cells. ³ Leptin is a hormone that regulates appetite and is secreted by fat cells. The group also suggested that infection could increase insulin sensitivity.

In 2010 and 2011 two studies reported no link between the presence of adenovirus-36 and body fat in individuals:

Goossens and co-workers found that adenovirus-36 does not play a role as a direct cause of BMI increase and obesity in humans in the Netherlands and Belgium.⁴ This iwas s in contrast to the United States, where Adenovirus-36 significantly correlates with obesity as illustrated by an Ad-36 seroprevalence of 30% in obese individuals and 11% in nonobese individuals. (Dr Atkinson replies here to the Goossens et al. study)

Broderick and co-workers showed no relationship between Ad-36 presence and obesity or serum cholesterol levels among US military personnel. ⁵ However, they did find a correlation between Ad-36 exposure and age, race and gender.

Recently, Waye has proposed a mechanism that involves oxidative stress in the pathology of Adenovirus-36 induced obesity. ⁶

At present there is still a lot of questions to be answered about the theory of viral-induced obesity. However, if obesity is caused by a virus it would be possible to prevent it by vaccinating humans against it. Obetech LLC is a company already investigating this possibility.

Image: human adenovirus



¹ Dhurandhar NV, Israel BA, Kolesar JM, Mayhew GF, Cook ME, Atkinson RL.(2000) Increased adiposity in animals due to a human virus. Int J Obes Relat Metab Disord. 24: 989-96.

² Vangipuram SD, Sheele J, Atkinson RL, Holland TC, Dhurandhar NV. (2004) A human adenovirus enhances preadipocyte differentiation. Obes Res. 12: 770-7.

³ Vangipuram SD, Yu M, Tian J, Stanhope KL, Pasarica M, Havel PJ, Heydari AR, Dhurandhar NV. (2007) Adipogenic human adenovirus-36 reduces leptin expression and secretion and increases glucose uptake by fat cells. Int J Obes (Lond). 31: 87-96. Epub 2006 May 16.

⁴ Goossens VJ, deJager SA, Grauls GE, Gielen M, Vlietinck RF, Derom CA, Loos RJ, Rensen SS, Buurman WA, Greve JW, van Baak MA, Wolffs PF, Bruggeman CA, Hoebe CJ. (2011) Obesity (Silver Spring). 19: 220-1. Epub 2009 Dec 10.

⁵ Broderick MP, Hansen CJ, Irvine M, Metzgar D, Campbell K, Baker C, Russell KL. (2010) Adenovirus 36 seropositivity is strongly associated with race and gender, but not obesity, among US military personnel. Int J Obes (Lond). 34: 302-8. Epub 2009 Nov 10.

⁶ Waye MM. (2011) New insights into how adenovirus might lead to obesity: An oxidative stress theory. Free Radic Res. May 26. [Epub ahead of print]

Controversies

There are a few popular idease that I am skeptical about. As an ex-scientist I'm well aware that data can be massaged to tell you exactly what you want to hear. However, when research that sounds controversial is published, it still makes for interesting reading and should be given due consideration.

There are many controversial issues around food. For example, the theory that artificial colours cause hyperactivity. In the April issue of Clinical Pediatrics, Dr Laura Stevens and co-workers reflect on 35 years of research looking for a causative link between artificial food colours and attention deficit hyperactivity disorder (ADHD).¹ It has been shown that a small subgroup of children respond to artificial colours, when challenged with at least 100mg. [Note: Typically just 10 - 50 mg is used in a kg of food ²] The authors note that recently, 2 large studies demonstrated behavioral sensitivity to artificial food colourings and benzoate in children both with and without ADHD. However, the study does start off stating that artificial food colors have not been established as the main cause of attention-deficit hyperactivity disorder.

At the University of Osnabrück in Germany, Dr Bodo Melnik has suggested a relationship between milk and type 2 diabetes. ³ This is a proposed mechanism only and is based on the idea that drinking milk after weaning may cause signalling in the pancreas. This might overstimulate β-cell proliferation in the pancrease, and ultimately will speed up β-cell senescence. Both β-cell proliferation and sensecence are hallmarks of type 2 diabetes. The author also mentions a link with Alzheimer's Disease - this is because type 2 diabetes has been linked to an increased risk of Alzheimer's disease. ⁴ Of course, milk has also been shown to be an exceptional recovery drink for sportsmen, giving even better results than special sports drinks. ^5,6

The latest sports-superfood is cherries. Researchers at London South Bank University have shown that Montmorency cherry juice consumption improves the recovery of isometric muscle strength after intensive exercise. ⁷ The researchers suggest that the cherries might have an anti-oxidative effect due to polyphenolic compounds including flavonoids and anthocyanins. [Interestingly, blueberries, chokeberries, European blackcurrants, elderberries and black raspberries contain significantly more flavonoids and anthocyanin than cherry ⁸]

On a non-food note, some researchers in China and the USA have published a case-control study investigating the link between breast cancer and sleeping with the light on.⁹ Subjects were identified in Connecticut, USA, and questioned with respect to their sleeping patterns and bedroom light environment. A non-significantly increased risk of breast cancer was observed among postmenopausal women for those keeping lights on while sleeping. This non-significant increased risk was also observed in women who reported mainly sleeping in the daytime and those not drawing the curtains while sleeping at night. The researchers conclude that this study suggest a potential increased risk of breast cancer associated with domestic exposure to light at night. Another group in Israel found a positive relation between breast cancer and light at night, and suggest that this may be due to disruption of the body's circadian clock.¹⁰ This correlation has not been found with lung cancer. <sup>11





1</sup> Stevens LJ, Kuczek T, Burgess JR, Hurt E, Arnold LE. (2000) Dietary Sensitivities and ADHD Symptoms: Thirty-five Years of Research. Clin Pediatr (Phila). 50: 279-93. Epub 2010 Dec 2.

² http://www.understandingfoodadditives.org/pages/Ch2p1-3.htm

³ Melnik BC. (2011) Milk signalling in the pathogenesis of type 2 diabetes. Med Hypotheses. 76: 553-9. Epub 2011 Jan 19.

⁴http://www.nature.com/nrneurol/journal/v2/n3/full/ncpneuro0124.html

⁵ Pritchett K, Bishop P, Pritchett R, Green M, Katica C. (2009) Acute effects of chocolate milk and a commercial recovery beverage on postexercise recovery indices and endurance cycling performance. Appl Physiol Nutr Metab. 34:1017-22.

⁶ Cockburn E, Stevenson E, Hayes PR, Robson-Ansley P, Howatson G. (2010) Effect of milk-based carbohydrate-protein supplement timing on the attenuation of exercise-induced muscle damage. Appl Physiol Nutr Metab. 35: 270-7.

⁷ Bowtell JL, Sumners DP, Dyer A, Fox P, Mileva KN. (2011) Montmorency Cherry Juice Reduces Muscle Damage Caused By Intensive Strength Exercise. Med Sci Sports Exerc. Jan 12. [Epub ahead of print]

⁸ http://www.mivelle.hu/sambucol/Flavonoid%20and%20Anthocyanin%20Content.pdf

⁹ Li Q, Zheng T, Holford TR, Boyle P, Zhang Y, Dai M. (2010) Light at night and breast cancer risk: results from a population-based case-control study in Connecticut, USA. Cancer Causes Control. 21: 2281-5. Epub 2010 Oct 7.

¹⁰ Kloog I, Portnov BA, Rennert HS, Haim A. (2011) Does the modern urbanized sleeping habitat pose a breast cancer risk? Chronobiol Int. 2: 76-80.

¹¹ Kloog I, Haim A, Stevens RG, Barchana M, Portnov BA. (2008) Light at night co-distributes with incident breast but not lung cancer in the female population of Israel. Chronobiol Int. 25: 65-81.

Taurine protects a donor heart

Some of us may know taurine in the following forms:

















However, recent research has shown that taurine can protect donor hearts from being damaged by blood deprivation.¹ Hearts from rats that were fed taurine showed less damage compared to hearts from rats fed a normal diet, when hearts were removed and kept on ice for 5 hours.

This study also pointed out that taurine infusion can protect the heart muscle if supplied before coronary artery bypass surgery and that dietary taurine can protect the heart from damage caused by heart attack.

Please note: energy drinks also have other ingredients which may not be good for your heart, so they definitely can't be considered a medicine!


¹Mehmet A Sahin, Orhan Yucel, Adem Guler, et al. (2011) Is there any cardioprotective role of Taurine during cold ischemic period following global myocardial ischemia? Journal of Cardiothoracic Surgery 6: 31

Source

More good bacteria

Not all bacteria are bad, as we know. There are "good bacteria" that live in our gut and help us to digest our food. Now, bacteria have been harnessed to help doctors and clinicians as a vector to treat or prevent disease. This bacterial gene therapy is known as "bactofection".

Peter Celec and his team in the Slovak Republic researched the usage of bacteria to treat inflammatory bowel disease.¹ The Salmonella bacteria carried genes for an antioxidant (superoxide dismutase) and a protein that stimulates the immune response (monocyte chemoattractant protein-1). Bactofection was applied to mice suffering from inflammatory bowel disease (colitis), and alleviated colitis symptoms in these mice when compared to untreated mice.

Listeria has been tested as a vector to deliver therapeutic genes and proteins to cancer cells and immune cells.² Listeria is a particularly good candidate as it is very efficient at entering host cells, and can move from cell to cell without having to exit it anywhere. Moreover it is safe and effective in clinical trials. Anti-cancer genes can be targeted to tumours by packaging them inside this pathogen.


Salmonella has also been used as a vehicle to treat cancer. ³ Both Listeria and Salmonella infect and can survive in antigen presenting cells (cells that form part of the immune system). They can be engineered to express tumour-like proteins which stimulates the body's immune system to break tolerance against tumour cells that look a lot like "self" to the body.



Image: Salmonella enterica serovar typhimurium



¹Palffy R, Gardlik R, Behuliak M, Jani P, Balakova D, Kadasi L, Turna J, Celec P. Salmonella-mediated gene therapy in experimental colitis in mice. Exp Biol Med (Maywood). (2011) 236:177-83.

²Tangney M, Gahan CGM. Listeria monocytogenes as a Vector for Anti-Cancer Therapies. Current Gene Therapy (2010) 10: 46-55.

³Paterson Y, Guirnalda PD, Wood LM. Listeria and Salmonella bacterial vectors of tumor-associated antigens for cancer immunotherapy. Seminars in Immunology (2010) 22: 183-189.

Gold nanocages

Prof. Younan Xia and his team invented gold nanocages (see below) for therapeutic applications. In a review¹ published in 2010, he explained how gold nanoparticles have gained an increasing interest due to their plasmonic characteristics. In particular, the metal can convert light into heat. This heat can be used for different applications, such as selectively releasing the drug contents of the nanocarriers once they have reached their target, or for photothermal therapy, where the heat generated by the nanoparticles destroy the cancer cells to which they are targeted.










¹Cobley CM, Au L, Chen J, Xia Y. Targeting gold nanocages to cancer cells for photothermal destruction and drug delivery. Expert Opin Drug Deliv. 7: 577-87 (2010)

The spirit is willing but the flesh is weak

If you're struggling to lose weight, it might actually be due to a chemical imbalance in your brain.

Researchers at the National Institutes of Health have shown that some obese individuals might have differences in the reward areas of the brain, compared to non-obese individuals.¹ The ability to resist the urge to eat needs to be stronger than the expected feeling of reward when we do eat. Some people seem to have an impairment in the brain area associated with reward sensitivity, and therefore their willpower is overwhelmed by the need to get that food reward.

[I wish this paper were open access as I'd love to know whether the researchers think one could break the conditioned response!]


¹Volkow ND, Wang GJ, Baler RD. Reward, dopamine and the control of food intake: implications for obesity. Trends Cogn Sci. 15:37-46 (2011).

Placebos as medicine

Did you know that your doctor may be giving you a placebo for your niggle? Well they very well may be. Antibiotics for flu? There you have one example already.

A recent survey was done by Kermen and co-workers¹ to determine how frequently American physicians prescribe placebos.Fifty-six percent (56%) of surveyed physicians reported prescribing or administering placebos in their practices, with younger physicians being a lot more likely to prescribe placebos than older physicians. The most frequently-used placebo was antibiotics (for non-bacterial diagnoses, 40%). The second most frequently prescribed placebo was vitamines (23%), followed by herbal supplements (12%). The most common reasons for prescribing placebos were “unjustified demand for medication” (32%) and “to calm patients” (21%). Most physicians (31%) told their patients that their presription consisted of a substance that will help and not hurt, and a very honest 2% told their patients that what they were given was an actual placebo. Most physicians believe that the placebo effect is beneficial and can have real, positive results.

So, while most physicians "believe" in the placebo effect, only about half would prescribe a substance that they knew had no direct therapeutic ingredient. Of course this was a very small study, but it makes one wonder what's happening in one's own surgery. It also reiterates the strong effect that thoughts can have on health.

¹ Kermen R, Hickner J, Brody H, Hasham I. Family physicians believe the placebo effect is therapeutic but often use real drugs as placebos. Fam Med. 42:636-42 (2010)
Source