Category Archives: Science in the News

Learning more about Tuberculosis from the Fur Trade

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.

Hide and Go Seek: HIV vs Mathematical Model

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.

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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.

See Video for more on the mathematical model.

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:
  1. direct viral killing of infected cells
  2. increased suicide rates in infected cells (most cells in our body are programmed to self destruct when they get old)
  3. 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.

Beetle feet inspire extra sticky glue

Source: robault.co.uk

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.

Source: sophiewasadog.wordpress.com

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.