Author Archives: Emily Fung

Track Your Stress with Sweat

Posted on March 27, 2019 | 4 comments

Do you hate having your blood drawn for your lab tests? Could there be a non-invasive way to obtain your lab results?  Perhaps, sweat samples could be used to measure our health status instead.

Sweating is a naturally occurring process, whether it is from exercising or getting nervous on a test. Although sweat can be perceived as wet and smelly, sweat contains various types of biomarkers, such as the stress hormone, cortisol. Since excessive stress can contribute to various health problems, such as high blood pressure, could we use cortisol in our sweats to monitor our stress levels in real-time?

In a recent study, Sekar et al. has developed a wearable electrochemical sensor that can measure cortisol in sweat. The researchers has integrated iron (III) oxide (Fe2O3) in conductive carbon yarn (CCY) to make a semiconductive platform. After that, the platform is coated with antibodies (anti-Cmab) in an electrochemical apparatus, which would make the sensor specific to cortisol. The final product would then become a Fe2O3/CCY immunosensor. The purpose of the study is to see if they can use CCY as a suitable platform for biosensors when monitoring sweats.

Adapted from Figure 1b in the Sekar et al (2019) paper. The black rectangle is the CCY with iron (III) oxide (orange spots). The green cylinder is the electrochemical apparatus. Licensed under a Creative Commons Attribution 4.0 International License

The researchers were able to test the sensor’s detection ability with different concentrations of cortisol. According to Figure 8b below, the line graph shows a linear relationship between the electrical current response from the Fe2O3/CCY immunosensor and the logarithm of cortisol concentration.

Adapted from Figure 8b in the Sekar et al (2019) paper. Each data point with error bar is the result from three successive experiments. Licensed under a Creative Commons Attribution 4.0 International License

The researchers also tested the sensor with real sweat samples from participants after performing cardio exercise. In the bar graph below, the error bars in the pink bar gives the RSD or relative standard deviation of 3.403%, 3.874%, and 4.064% from sweat sample 1, 2, and 3 respectively. These RSDs show small variations in averaged results from three successive experiments when testing with the Fe2O3/CCY immunosensor. According to the paper, the bar graph below shows a correlation between the two methods: the CLIA (chemiluminescence immunoassay) and their Fe2O3/CCY immunosensor. As a results, using CCY may be a possible choice for designing a biosensor that monitors cortisol in sweats.

Adapted from Figure 11 in the Sekar et al (2019) paper. Each pink bar with error bar is the result from three successive experiments. Licensed under a Creative Commons Attribution 4.0 International License

In addition, there are other similar studies that focus on wearable sweat sensors, such that they can transmit data to your phone, and diagnose cystic fibrosis. Therefore, sweat sensors are potential non-invasive diagnostic tools, which may lessen the burden on more invasive blood samples to measure our health status.

References

Stress and Heart Health. https://www.heart.org/en/healthy-living/healthy-lifestyle/stress-management/stress-and-heart-health (accessed Mar 26, 2019).

Sekar, M.; Pandiaraj, M.; Bhansali, S.; Ponpandian, N.; Viswanathan, C. Carbon fiber based electrochemical sensor for sweat cortisol measurement. Scientific Reports 2019, 9, 1-14. https://doi.org/10.1038/s41598-018-37243-w.

Stephanie, Relative Standard Deviation: Definition & Formula. https://www.statisticshowto.datasciencecentral.com/relative-standard-deviation/ (accessed Mar 26, 2019).

Geddes, L. Wearable sweat sensor paves way for real-time analysis of body chemistry. http://www.nature.com/news/wearable-sweat-sensor-paves-way-for-real-time-analysis-of-body-chemistry-1.19254 (accessed Mar 26, 2019).

Dusheck, J. Wearable sweat sensor can diagnose cystic fibrosis, study finds. http://med.stanford.edu/news/all-news/2017/04/wearable-sweat-sensor-can-diagnose-cystic-fibrosis.html (accessed Mar 26, 2019).

 

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Is it actually 100% oregano?

Posted on March 9, 2019 | 6 comments

Have you ever wondered what is in the food you eat? This pizza may contain additional ingredients that you may not be aware of.

According to Canadian Food Inspection Agency (CFIA), food fraud is an emerging global issue. In fact, food fraud “may cost the global food industry $10 to $15 billion per year”. Examples of food fraud may include substitution/addition of ingredients or tampering/mislabeling of food packages, and selling these inferior products at a higher price for profit. Food fraud is problematic; therefore, it is crucial that CFIA and the food industry combat food fraud to protect consumer safety.

However, in 2016, there has been a report of adulterated dried oregano in Australia. Some brands that declare “100% oregano” only have 33% – 50% of actual oregano. The remaining percentage could contain additional olive and myrtle leaves as fillers. The presence of olive and myrtle leaves can pose a health risk, because it can carry a higher amount of pesticides, which can contaminate the dried oregano. Therefore, it is important to find a way to detect these fillers, so that they can be eliminated from the market.

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Recently, a paper from the journal of Food Chemistry published in 2019, suggests that GC-MS (a common instrument in a Chemistry lab) can be used to detect and measure the amount of pesticides in adulterated oregano samples. By identifying the most predominant pesticides in adulterated oregano, the pesticides can be used as potential markers for identifying adulterated oregano.

But how does GC-MS work? In the “GC” part of the instrument, the pesticides travel through the column, in different speeds, based on its unique chemical properties. Once all of the pesticides are separated, they go through the “MS” part of the instrument, where they get fragmented by a beam of electrons before it travels through the mass analyzer and reaches to the detector for data collecting (see image below).

A schematic of the GS-MS instrument. Detector is attached to the right side of the mass analyzer (not shown). Cwszot, Kkmurray, Creative Commons  Attribution 2.5 Generic (CC BY 2.5), Electron ionization GC-MS.png

As a result, pesticides (cyfluthrin (sum), cyhalothrin lambda, and pyriproxfen) are present in higher quantity in the 34 adulterated oregano samples than in the 42 genuine samples. Therefore, cyfluthrin, cyhalothrin lambda, and pyriproxfen could be used as potential markers for detecting adulterated oregano.

Graph from the research paper. Click on the image for high-definition. Drabova et al., Creative Commons Attribution 4.0 International (CC BY 4.0),  Adapted from Figure 5 in Food fraud in oregano: Pesticide residues as adulteration markers

In conclusion, it is possible to identify the adulterated samples by using a chemical technique to stop food fraud. Although CFIA and food industries work to protect consumers from food fraud, CFIA suggests a few ways for consumers to identify food fraud.

But as for me, I will stick to growing my own oregano in my backyard.

Updated: March 28, 2019 

Reference:

Canadian Food Inspection Agency. The CFIA Chronicle. http://www.inspection.gc.ca/about-the-cfia/the-cfia-chronicle-fall-2017/food-fraud/eng/1508953954414/1508953954796 (accessed Mar 08, 2019).

Canadian Food Inspection Agency. Food fraud. http://www.inspection.gc.ca/food/information-for-consumers/food-safety-system/food-fraud/eng/1548444446366/1548444516192 (accessed Mar 08, 2019).

Canadian Food Inspection Agency. Types of food fraud. http://www.inspection.gc.ca/food/information-for-consumers/food-safety-system/food-fraud/types-of-food-fraud/eng/1548444652094/1548444676109 (accessed Mar 08, 2019).

The Sydney Morning Herald. Food Fraud: Popular oregano brands selling adulterated products. https://www.smh.com.au/business/consumer-affairs/food-fraud-popular-oregano-brands-selling-adulterated-products-20160405-gnygjo.html (accessed Mar 08, 2019).

Drabova, L., Alvarez-Rivera, G., Suchanova, M., Schusterova, D., Pulkrabova, J., Tomaniova, M., . . . Hajslova, J. Food fraud in oregano: Pesticide residues as adulteration markers. Food Chemistry. [Online] 2019, 276, 726-734. doi:10.1016/j.foodchem.2018.09.143 (accessed Mar 08, 2019).

Canadian Food Inspection Agency. How food fraud impacts consumers. http://www.inspection.gc.ca/food/information-for-consumers/food-safety-system/food-fraud/how-food-fraud-impacts-consumers/eng/1548444986322/1548445033398  

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Forensic: How to Measure the Unknown Time of Death from Only Bone and Hair Remains

Typically, TV forensic shows, such as CSI and Bones, portray how forensic cases are fast and easy to solve within a couple of episodes. However, that is not true. Unlike in forensic shows, forensic cases take a long time to solve in real life, due to challenges that investigators have to face.

One of the challenges that criminal investigators have to solve is to determine the post-mortem interval (PMI) from decomposed skeletons. Post-mortem interval is the time after someone has died, which is important when the cause of death is unknown. Usually, medical assessment of corpses can determine the PMI after the body is dead for the first few days. However, when the victim’s bones and hairs are found after a few years, the accuracy of the PMI lowers. Therefore, new method is required to provide a more accurate estimation of the extended time of death.

Currently, there are numerous studies that use different methods for solving the PMI. Many methods include analyzing soil chemistry and insects at the crime scene. Since these methods could be complementary to each other, the scientists in Switzerland believe that combining these methods would improve the long-term PMI estimate, while illustrating how the crime scene could have occurred. Therefore, the Swiss scientists have attempted to use five different approaches simultaneously to estimate the PMI of the bone and hair remains. Once the soil, bone, and hair samples are collected from the Swiss forest, the scientists use five different approaches for analyses, which include using radiocarbon dating, analyzing pH and soil chemistry, counting and classifying nematodes and mites, and sequencing DNA of soil micro-eukaryotes.

 

After analyzing the findings, the scientists are able to propose a possible PMI, as well as the crime scene. First of all, the radiocarbon dating determines that the bones belong to a young adult male. Secondly, chemical, nematodes, and micro-eukaryotic analyses suggest that the remains have been partly decomposed in the forest for at least 8-9 months. Finally, the evidence from mites suggests that the corpse is partly decomposed in a separate confined place, because these mite species are only found in confined environment. Therefore, the suspect(s) could have allowed the corpse to decompose in a confined area before relocating it to the Swiss forest. As a result, the PMI of the dead victim appears to be at least 8-12 months before the body is discovered.

The skeleton that is found in a Swiss forest. Ildikó Szelecz, Sandra Lösch, Christophe V. W. Seppey, Enrique Lara, David Singer, Franziska Sorge1, Joelle Tschui, M. Alejandra Perotti & Edward A. D. Mitchell, Source, Creative Commons Attribution 4.0 International Licence

Overall, the study shows that using five approaches simultaneously in a forensic case study can estimate the PMI, while illustrating a possible crime scene of how the victim could have died. Moreover, all of the approaches can be complementary with each other, in order to provide more evidence from scarce remains. In conclusion, it is possible to further develop this technique in order to estimate PMI in other forensic cases.

Update: Blog post has been revised on 2019, Feb 15th.

Reference

Rasmussen College. How Accurate are Crime Shows on TV? Debunking 7 Common Myths. https://www.rasmussen.edu/degrees/justice-studies/blog/crime-show-myths-debunked-forensic-experts-tell-what-life-is-real/

Keele University. Chemical Ecology. PMI in Forensic Entomology. https://www.keele.ac.uk/chemicalecology/projects/pmi/

American Council on Science and Health. How Chemistry, Microbiology Could Help Catch A Killer. https://www.acsh.org/news/2018/01/18/how-chemistry-microbiology-could-help-catch-killer-12422 .

Szelecz, I.; Lösch, S.; Seppey, C. V. W.; Lara, E.; Singer, D.; Sorge, F.; . . . Mitchell, E. A. D. . Comparative analysis of bones, mites, soil chemistry, nematodes and soil micro-eukaryotes from a suspected homicide to estimate the post-mortem interval. Scientific Reports. [Online] 2018, 8(1), 25. doi:10.1038/s41598-017-18179-z.

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Posted on January 29, 2019 in Biological Sciences, Science in the News, Uncategorized

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