One of the most memorable things when learning about the 18th century Canadian fur trade in history class was how the Europeans spread diseases to the indigenous peoples by means of the trade. One of such diseases is tuberculosis, which infectious disease specialist Caitlin Pepperell and colleagues at Standford University in Palo Alto, California have been studying. In the new study published in the Proceedings of the National Academy of Sciences, they have puzzled out why TB didn’t become an epidemic until after the fur trade era even though the indigenous peoples of western Canada were repeatedly exposed to the strain by French Canadian voyageurs during 1710 – 1870.
Canadian Fur Trade / Source:Cartouche from William Faden
It wasn’t until the late 1800s that TB epidemics began to break out, which was about 150 years from the first introduction. Pepperell explains that the conditions most likely to trigger epidemics in Canada were the relocation of the native peoples onto reservations, declining health conditions with relocation, and the biggest factor of them all, malnutrition. The key message from the results indicates that TB is infectious and remains dormant in host until stressful conditions – crowding, poor nutrition, weakening hosts – give the bacteria a leg up and turns on into active mode.
TB Culture / Source: CDC
Pepperell first discovered the same TB strain signature, or “fingerprint” in the native peoples of Quebec and a French Canadian population that didn’t live near the native communities when she received a DNA profile of the bacteria in the latter from a colleague. After using mathematical modeling and statistical analysis, they were able to trace the spread back to the 18th century, which was when waves of French traders carrying TB came to Canada and married indigenous women, resulting in the disease remaining latent in the native communities for several decades until the pressures of relocation and shortage of buffalo occurred.
Tuberculosis’s stealth nature has had it difficult to combat the disease without knowing how it spreads. The World Health Organization estimates that 1/3 of the people on Earth are infected with the disease. The new findings of the study can only point out how tenacious the disease actually is, bring us one step closer to understanding the tuberculosis bacterium and how we can control it.
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Math may help overcome ‘sleeper cell’ hurdle in HIV treatment
New research on HIV treatment is important for helping the 33 millionpeople who are affected in North America, Sub-Saharan Africa and the rest of the world.HIV is a Human immunodeficiency virus. It is a condition in humans where the infection causes the immune system to fail, leading to life threatening infections and diseases.
The HIV virus can survive in two places in the body; inside cells or free floating in the blood.Inside a cell, the HIV virus has two options it could begin making copies of itself using the cells own DNA xerox machine, once enough copies are made the new viruses can break out of the cell and go on to infect other cells in the body. Other times the virus may simply hide out in the cell in a dormant phase. This dormant phase is what makes antiretroviral medication less than 100% effective. The medication can only target the free viruses and the ones that are making copies. The ones that are hiding could become active later on with out any warning.
See podcast for more on dormant cells.
The unpredictable activation of dormant cells led to some unique research by mathematicians at the University of British Columbia. They have used a mathematical model to track and predict how virus levels change in a patient when the dormant cells wake up. The research shows that these cells don’t wake up because of a trigger (like failing drug treatment) but are due to random activations.
HIV can be detected through the screening of the blood. HIV infection occurs by the transfer of bodily fluids such as breast milk, blood, semen, vaginal fluid and pre-ejaculate. The most common routes of transmission of the infection is through unprotected sex, contaminated needles, breast milk and transmission from an infected mother to her child at birth.
The mechanism behind HIV is that it primarily infects the cells in the human immune system (T cells, white blood cells, macrophages and dendritic cells) which essentially protect the human body from infections. CD4+ T cells are a type of white blood cell that guides other white blood cells to fight infections. HIV infection leads to low levels of these CD4+ T cells, through three main mechanisms:
direct viral killing of infected cells
increased suicide rates in infected cells (most cells in our body are programmed to self destruct when they get old)
killing of infected CD4+ T cells by CD8 cytotoxic lymphocytes that recognize infected cells. These are like cops that hunt down the infected cells.
When the level of CD4+ T cells declines to a critical level, the protection provided by white blood cells is lost, and the body becomes more susceptible to infections. This is commonly known as AIDS.
Posted onApril 10, 2011bypaula|Comments Off on Could DNA testing for genetic conditions lead to a society supporting eugenics?
The BBC recently wrote an article regarding the genetic test that was approved, allowing people to get tested for genetic conditions before pregnancy. Though this test has the potential to be very beneficial and prevent people from creating families if they would be at a high risk of carrying a genetic disorder if they so choose, it also has the potential to create a stigma around people who test positive for genetic disorders.
Upon being tested and finding positive results, would our society then tell those people that they should be be banned from having families and children? Knowing that you had a higher chance of carrying a genetic disorder would perhaps cause one to feel as though they had a moral obligation to be tested to prevent the disease from being passed onto others. This would cause a stigma on those who test positive for any such diseases.
This video shows another aspect of the implications of having genetic testing done.
The definition of eugenics as given by the Apple dictionary says it is, “The science of improving a human population by controlled breeding to increase the occurrence of desirable heritable characteristics.” By using technology that can be available to us because of a progression in research is not always a good idea. By implementing this as a normal test into health care systems, there would be a great possibility that our society would lead to being in favor of eugenics.
Other factors which would be a greater concern to Americans, would deal with wether or not health insurance companies could take this information into account, or even have mandatory testing for certain groups of people. This is not a topic to be taken lightly, but rather one that should be well thought out before the test is planned to be used on a regular basis which could have negative impacts on our generation.
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We interviewed Andres to discuss the global whale hunting controversy and how coastal countries can profit from whale watching in this video.
We further discussed with Andres the importance of whales in the ecosystem in this podcast.
Whale watching is more than sitting on a boat and viewing just whales. It is going out into the natural environment of whales and viewing all the marine species who share the water with the whales. It has significant educational and environmental benefits and provides an outlet to study the whales scientifically. There are also economic benefits both locally and globally. Whale watching has the potential to expand the tourism market, which will promote all the local businesses and restaurants. Jobs are created when locals are trained as guides. They can combine local knowledge such as traditional encounters with the whales with scientific knowledge about the whales.
Whale watching as an alternative to whaling is an idea being promoted around the world. The International Fund for Animal Welfare (IFAW) wrote up a global proposal for whale watching as a sustainable alternative. They estimated that the whale watching industry profited 1-billion dollars in 2001. Recent findings by Andres Cisneros from the University of B.C. found that whale watching could potentially profit 2.5 billion dollars worldwide. His model estimates the value of whale watching could be worth double the amount compared to 10 years ago if countries begin to expand their whale watching industry.
Regulations are being put in place to make sure whales and their environment are respected. The IFAW is one of the main groups who promotes responsible whale watching. Responsible whale watching is a global code of conduct for how whales should be treated. This is to prevent the harassment of the whales and reduce intrusions into their environment by the whale watching boats. There are concerns that a large number of boats and people may disturb whale migration and feeding habits.
There is also a need to change some of the tourism laws to allow local fishermen to act as whale watching guides.This will provide more work and give them an opportunity to expand their employment beyond just fishing. This problem was brought to Andres’ attention on a recent trip to Panama. “I was just down talking to fishermen in Panama and they were saying ‘sometimes the fishing is not very good and we know that there are whales out there and we would like to maybe ask the tourists if they want to pay us and we would take them to where we know there are whales’ and they are not letting them do that right now because of some tourism laws that they have down there.”
Whale watching is a way to use whales as a sustainable resource. It provides jobs and reduces the harm done to whales and their environment. Some countries are realizing the potential profit that whale watching can but many more can join in and stop commercial whaling. There needs to be regulation on this growing whale watching industry to make sure it is practiced ethically.
The UK company Sea Life Surveys has a video on how they run their responsible whale watching trips.
Post created by : Shirley Huang, Kate MacMillan, Irfan Haji, James Kirkbright
Like many insects, beetles can walk upside down without falling due to the extremely sticky structures of their foot pads. Scientists James Bullock and Walter Federle from the University of Cambridge recently published a study in the journal Naturwissenschaften (The Nature of Science) that found different hair structures have different levels of stickiness. Their study is the first to measure the adhesive strength of a single seta, the adhesive hairs that are responsible for the “stickiness” of the beetle’s feet.
The researchers found there were three different structures of setae on the foot pads: pointed, flat (spatula-tipped) and disk-like. The three structures have different functions depending on the specific pattern they are arranged in. Each of these structures is made up of thousands of microscopic hairs and prior to this study there was no way to determine the adhesiveness of one individual hair due simply to their microscopic size.
By using an extremely fine glass cantilever and measuring the deflection of the cantilever with a microscope, the exact force needed to detach each hair was calculated. By use of this novel technique the researchers were able to calculate the exact stickiness of each hair, which are only 5 micrometers across.
Of the three different seta structures the disk like hairs had the greatest level of stickiness, followed by the spatula shaped hairs, with the pointed hairs coming in least sticky. The most sticky hairs were also the most stiff, most likely providing stability to the foot-pad. The researchers hypothesize it is these disk-like hairs that are particularly responsible for the strong adhesion the beetles have to smooth surfaces, such as the underside of a leaf.
This adhesion is also important during mating so that males can attach themselves to a female’s back. The other hair structures which aren’t as sticky are probably used for adhesion while running because they are quicker and easier to unstick.
This new understanding of the beetle’s sticky feet may one day lead to the creation of bio-inspired synthetic adhesives, such as extra sticky super glue.