Author Archives: gloriak

Effects of Caffeine in Our System

Posted on November 7, 2016 | 4 comments

At some point in your life you may have gotten only a couple hours of sleep or even pulled an all-nighter for an exam or a project. A quick solution to sleep deprivation is often coffee, energy drinks, soft drinks, or tea, to name a few. All of these drinks have a common ingredient, caffeine (1).

Caffeine is a molecule that stimulates activity in the central nervous system (3). Caffeine inhibits binding of adenosine, which is a type of neurotransmitter that is essential in promoting sleep in the central nervous system, to cell receptors (4).

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There are evidence to support that ingesting caffeine is an effective way in compensating for sleep deprivation. The researchers at the University of Sfax in Tunisia concluded from a study that ingesting caffeine can improve physical and cognitive performances, and counteract 36 hours of sleep deprivation (5). Souissi and colleagues conducted the study using 13 healthy male students with similar height, age, and weight (5).

Some participants were given 8.5 hours of rest and/or sleep time, while the other participants were sleep deprived for 36 hours by keeping televisions on throughout the sleeping hours (5). Then the participants from each group either ingested a placebo, which is essentially a sugar pill, or a caffeine pill (5). The participants’ physical and cognitive performances were measured by squat jump performances and the Wingate anaerobic test using a cycle ergometer (5). The Wingate test is generally used to measure the energy output of a person’s anaerobic cycling performance (2). The participants’ reaction time were determined from both squat jump performance and Wingate anaerobic test (5). By comparing the reaction times of both groups, the researchers concluded that ingesting caffeine improved cognitive and physical performances more prominently for the group that was deprived of sleep for 36 hours(5). Hence, caffeine has its benefits in helping us function on days when we are sleep deprived.

Although caffeine has its benefits on improving physical and cognitive performances over a short time period, caffeine should be consumed in moderation. Higher doses of caffeine can result in numerous side effects which include insomnia, tremor, headaches, and cardiovascular and respiratory failures (3). Perhaps further studies should be conducted on the relative effects of caffeine on people that differ in age, height, weight, health, and other factors compared to the participants in Souissi and colleagues’ study.

–Gloria Kwong

 

References:

  1. Bender, D. A. A Dictionary of Food and Nutrition: Caffeine (4th edition). Oxford University Press, 2014. http://www.oxfordreference.com/view/10.1093/acref/9780191752391.001.0001/acref-9780191752391-e-960?rskey=reGySA&result=1 (accessed November 5, 2016).
  2. Beneke, R.; Pollmann, C.; Bleif, I.; Leithauser, R.; Hutler, M. How anaerobic is the Wingate Anaerobic Test for humans. Eur. J. App. Physiology, 2002, 87, 388-392. http://link.springer.com.ezproxy.library.ubc.ca/article/10.1007%2Fs00421-002-0622-4 (accessed November 5, 2016).
  3. Colman, A. M. A Dictionary of Psychology: Caffeine (4th edition). Oxford University Press, http://www.oxfordreference.com.ezproxy.library.ubc.ca/view/10.1093/acref/9780199657681.001.0001/acref-9780199657681-e-1217 (accessed November 5, 2016).
  4. Roehrs, T.; Roth, T. Caffeine: Sleep and daytime sleepiness. Sleep Medicine Reviews, 2008, 12, 153-162. http://www.sciencedirect.com.ezproxy.library.ubc.ca/science/article/pii/S1087079207000937?np=y (accessed November 5, 2016)
  5. Souissi, M.; Chtourou, H.; Abedelmalek, S.; Ghozlane, I. B.; Sahnoun, Z. The effects of caffeine ingestion on the reaction time and short-term maximal performance after 36 h of sleep deprivation. Physiology and Behaviour, 2014, 131, 1-6. http://www.sciencedirect.com/science/article/pii/S0031938414002030 (accessed November 3, 2016)

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The Anti-microbial Properties of Silver Nanoparticles on Titanium Implants

Posted on October 17, 2016 | 1 comment

Titanium is commonly used to make implants (3). However, the implant’s surface poses as a health issue when bacteria can adhere and prevent the skin tissues from healing properly with the implant following surgery (3).

A recent publication in Nature’s Scientific Reports by Wang and colleagues showed supportive evidence that titanium surface combined with silver (Ag) nanoparticles and silver ions (Ag+) release are able to inhibit the growth of Staphylococcus aureus, which is a spherical non-motile type of bacteria that is commonly found in skin and mucous membranes (2), and other strains of Staphylococcus, such as S. epidermis, that are motile (3).  

1 pixel = 0.038 uM 100X objective 15X eyepiece Numbered tick = 11 uM Field of view is 85.12 uM in diameter

Figure 1. Staphylococcus Under Magnification (Image Courtesy of Wikimedia Common; Author: Bob Blaylock; Source: Picture Uploaded by Original Photographer)

 Wang and colleagues varied the amount of Ag nanoparticles (Ag-0, Ag-0.01, Ag-0.1) on titanium plates and exposed bacteria to the surfaces (3). In doing so, they found that higher amounts of Ag nanoparticles had higher antimicrobial properties for motile and non-motile bacteria compared to lower amounts of Ag nanoparticles or titanium plates alone (3).  Moreover, Wang and researchers analyzed how Ag nanoparticles affected the biofilms of non-motile bacteria. By definition, biofilms are a bacterial population that is held together by extracellular matrix, which are molecules secreted by individual bacteria cells (1).

staphylococcus_aureus_bacteria_7739552618

Figure 2. Scanning electromicrograph of Staphylococcus aureus. (Image Courtesy of Wikimedia Common; Author: National Institute of Allergy and Infectious Diseases (NIAID); Source: Picture Uploaded on Flickr)

Wang and colleagues observed that bacterial populations grew under Ag-0 and titanium plate alone. While, there was a significantly smaller bacterial population under Ag-0.01 and no biofilm was formed under Ag-0.1. Wang and colleagues also applied both bacterial and mammalian cells to a titanium plate with varying concentrations of Ag nanoparticles (3). They observed that over time, Ag-0.01 had developed a comparatively large population of mammalian cells attached to the plate.  While Ag-0.1 had little growth of mammalian cell population, and both Ag-0 and titanium plate alone showed no living mammalian cells (3).

Biofilms of bacteria, such as Staphylococcus, are one of the main reasons why people have infections following an implant. Due to supportive evidence of antimicrobial properties and mammalian cell growth in Ag nanoparticles, further studies should be conducted on the appropriate concentrations of Ag nanoparticles to be integrated into the surface of titanium implants in hopes that future patients will have successful implants.

–Gloria Kwong

References:

  1. López, D.; Vlamakis, H.; Kolter, R. Biofilms. Cold Spring Perspectives in Biology 2010, 2 (7). http://doi.org/10.1101/cshperspect.a000398 (Accessed October 17th, 2016).
  2. Martin, E. Staphylococcus; 2015. http://www.oxfordreference.com.ezproxy.library.ubc.ca/view/10.1093/acref/9780199687817.001.0001/acref-9780199687817-e-9542 (Accessed October 17th, 2016).
  3. Wang, J.; Li, J.; Guo, G.; Wang, Q.; Tang, J.; Zhao, Y.; Qin, H.; Wahafu, T.; Shen, H.; Liu, X.; Zhang, X. Silver-nanoparticles-modified biomaterial surface resistant to staphylococcus: new insight into the antimicrobial action of silver. 2016, 6, 32699.

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The Truth Behind Silver and Titanium Oxide Nanoparticles

Posted on September 26, 2016 | 1 comment

Commercial products, such as cosmetics and paints (4), contain titanium oxide (TiO2) nanoparticles; antimicrobial agents, fabrics, and food preservatives (5) contain silver (Ag) nanoparticles.  Nanoparticles, synthetically made molecules that range in size from 1 nm to 100 nm (5), are found in every day household items.

clustered_titanium_oxide_nanoparticles_on_stainless_steel_-_3

Titanium Oxide Nanoparticle on Stainless Steel (Image Courtesy of Wikimedia Common; Author: Iuliia Karlagina; Source: Picture Uploaded by Original Photographer)

A recent publication in the Journal of Environmental Toxicology and Pharmacology by researchers at National Tsing Hua University in Taiwan revealed the potential risks that nanoparticles of TiO2 and Ag as well as Ag+ ions pose to the blood-brain barrier of animal cells (2). Chen and fellow colleagues (2) simulated the conditions of the blood-brain barrier in vitro. As illustrated in the figure below, the blood brain barrier is a highly selective membrane that only allows specific molecules, such as glucose and insulin, and ions to pass between the blood and the brain (1).

blood-brain-barrier

Blood-Brain Barrier (Image Courtesy of Wikimedia Commons; Authors: Helen Stolp, Shane Liddelow, Ines Sa-Pereira, Katarzyna Dziegielewska, Norman Saunders; Source: Journal Article)

The study (2) concluded that silver nanoparticles not only affect the selectivity of the blood-brain barrier, but it can lead to a higher likelihood of genetic mutations and even cell death. Due to the small size of silver nanoparticles (8.4 nm) and TiO2 nanoparticles (6 nm) (2), they were able to bypass the selective membrane and enter into the central nervous system.  Furthermore, the silver ions and titanium oxide nanoparticles can alter the permeability of the blood-brain barrier by cell-to-cell interactions, known as cytokine secretions (2). This effect is further intensified in the presence of lipopolysaccharide, which is a type of molecular marker found on the surface of gram-negative bacteria (6). Their findings suggest that when we are pre-exposed to TiO2 and/or Ag nanoparticles while fighting a bacterial infection, our bodies will elicit an immune response that can be detrimental to our brain-blood barrier (2).

This study provides a stepping stone for future studies to be performed in determining the potential health risks associated with other types of inorganic or synthetic nanoparticles, commonly found in commercial products. Personally, for the safety and well-being of people, re-establishment of national and global guidelines on the commercial use of nanoparticles is necessary.

–Gloria Kwong

References

  1. Abbott, N. J., Patabendige, A. A. K., Dolman, D. E. M., Yusof, S. R., & Begley, D. J. (2010). Structure and function of the blood–brain barrier. Neurobiology of Disease, 37(1), 13-25.
  2. Chen, I.-C.; Hsiao, I.-L.; Lin, H.-C.; Wu, C.-H.; Chuang, C.-Y.; Huang, Y.-J. Environmental Toxicology and Pharmacology 2016, 47, 108–118.
  3. Clett Erridge, Elliott Bennett-Guerrero, Ian R. Poxton, Structure and function of lipopolysaccharides, Microbes and Infection, Volume 4, Issue 8, July 2002, Pages 837-851, ISSN 1286-4579.
  4. Gupta, S.; Tripathi, M. Open Chemistry 2012, 10 (2).
  5. Rai, M.; Yadav, A.; Gade, A. Biotechnology Advances 2009, 27 (1), 76–83.
  6. Stow, J. L.; Low, P. C.; Offenhäuser, C.; Sangermani, D. Immunobiology 2009, 214 (7), 601–612.

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