Tuesday, December 14, 2010

There was a sudden onset of apprehension, followed by potentially violent cold shivers, headache, body pains and exhaustion. Then, after a few hours, there was profuse sweat followed by heat, headache, delirium, rapid pulse with heart pain and palpitations, intense thirst and in many cases, death within 24 hours.

The English sweat (AKA sweating sickness) was a deadly epidemic disease in England in the 1500s around the time of Henry VIII. I became interested in this after I saw it in The Tudors (A semi-historic series about Henry VIII). I wasn’t familiar with the disease, so I thought it might make a good topic for this blog. The disease is distinct from the plague (Yersinia pestis) and based on the descriptions, it was devastating, but not of the same magnitude as the plague. There were several outbreaks of the Sweating Sickness during the first half of the 1500s. The disease, as it was described, has never been seen since in the form of an outbreak or epidemic and, consequently, the cause remains a mystery. Using the symptoms and circumstances surrounding the outbreak, some scientists and historians have speculated about the cause of the disease. At first, the possibilities seem limited, as there are few diseases today that strike populations with the same severity among so many people especially in the northern latitudes of Europe. Hantavirus, Louse borne typhus, relapsing fever, influenza and even chronic fatigue syndrome have been suggested in the medical/history literature based on symptoms and infection patterns.

How could a disease like sweating sickness appear in a population, infect many individuals with devastating results, reappear again a few times over the course of several decades, and then vanish? There is little information available in the scientific literature other than historic accounts and speculation but I think that the following three scenarios are plausible:

1. Perhaps the sweating sickness was not one disease but several more common diseases that were confused by the poor science and medicine of the time (e.g. Brucellosis, Malaria, Typhoid fever). In other words, there was no real single disease epidemic.

2. Perhaps the few epidemics were sparked from chance encounter with an exotic/tropical virus that was able to gain only a temporary foothold and make a few rounds in Europe before fizzling out during the 16th century. Possibly, this could have been aided by unusually warm weather.

3. It is possible that the agent of the disease emerged within Europe through the transformation of a more harmless common microbe into a killer. After making a few rounds, the disease induced broad immunity in the population preventing further epidemics of such large magnitudes. It could still be around today.

Wednesday, February 24, 2010

Immortal cells and transmissible cancers

Although Henrietta Lacks died of cancer almost 60 years ago, in a way, she still lives on. Prior to her death in the early 1950s, her cancer cells were collected by her doctor and grown outside of her body in a laboratory. Over the years, HeLa cells (as they were called to protect her identity) have been used for many experiments resulting in some very important scientific breakthroughs, such as development of a polio vaccine. These cells are special because, unlike most human cells, they are immortal. They have no limit (Hayflick limit) to cell division. Consequently, they reproduce and multiply is such a way that makes them relatively easy to grow in a tissue culture. They have evolved into what some consider a new species with an erie independence that can, at times, even be disruptive to researchers. HeLa cells have been known to contaminate other cell lines and grow "wild" within laboratories. While normal human cells have 46 chromosomes (23 pairs), HeLa cells have 76-80 chromosomes. When planted into animal tissue, HeLa cells can grow and produce a tumor, demonstrating that cancers can be transmissible. In general, other types of cancer cells share this pervasive behavior and immortality with HeLa cells. This has tragically been observed when human cancers are accidentally passed on to others from transplanted organs. While HeLa cells and other human cancers are transmissible only by artificial means (as far as we know), Devil facial tumor disease (DFTD) is an example of transmissible cancer that occurs in nature. This transmissible cancer of the grumbly little marsupials down under known as the Tasmanian Devil may severely imperil their populations. When devils bite each other, they pass on these cancer cells, which are derived from Schwann cells that normally support nerve cells. The devil's tumor cells have fewer chromosomes than the normal cells (13 instead of 14). Dogs also suffer from a form of transmissible cancer call Canine Transmissible Venereal Tumor (CTVT). Unlike devils, this cancer is sexually transmissible between dogs. Of course, the transmissibility of cancer agents is well known and widespread and not new. Viruses such as Hepatitis B, Hepatitis C, HPV and many others are known to cause cancer. However, this is quite different from transmissible cancers where the cancer cells themselves (rather than a virus) are passed on from one body to the next and continue dividing uncontrollably.

Sunday, December 27, 2009

The meaning of life

The organism Mixotricha paradoxa exemplifies the problems of biological classifications and the overly-simplistic views about life on earth that modern biologists are trying to abandon. This microscopic “organism” lives in the gut of termites and helps the termite digest cellulose (fiber). When it was first described in 1933, Mixotricha looked like a single-celled organism with little hairs like cilia all over it and a whip-like tail to help it move. However, decades later, upon further scrutiny, these accessory structures on the Mixotricha turned out to be separate organisms. The thousands of cilia-like structures are actually spirochete bacteria and the “tail” is yet a different bacterium. So, what at first appears to be AN organism is actually several different organisms that depend on each other for survival (a form of symbiosis called mutualism). Or, perhaps it should be classified as one composite organism (E pluribus unum!). After all, consider the human organism. Each human body is an organism with more bacterial cells living on and in it than the number of human cells in it. Furthermore, in every one of the human cells reside tiny little mitochondria. They each have their own circular DNA molecule, which is very similar to bacterial DNA. Mitochondria replicate inside of our cells and carry out metabolic reactions, which benefit our cells and allow us to live. Living things evolve through complex mergers and separations of life systems. Two become one, one becomes two etc…Perhaps the concept of life is stated best by Lynn Margulis, a renowned symbiologist.

" 'What is life?' is a linguistic trap. To answer according to the rules of grammer, we must supply a noun, a thing. But life on Earth is more like a verb. It is a material process, surfing over matter like a strange slow wave. It is a controlled artistic chaos, a set of chemical reactions so staggeringly complex that more than 4 billion years ago it began a sojourn that now, in human form, composes love letters and uses silicon computers to calculate the temperature of matter at the birth of the universe."

Thursday, December 17, 2009

Leprosy and other related diseases

Leprosy (Hansen's Disease) is a chronic bacterial infection of the skin and peripheral nerves. The agent Mycobacterium leprae is a close relative of the bacterial agent of tuberculosis (Mycobacterium tuberculosis). DNA from both of these bacteria has been found in ancient human remains and artifacts. The belief that leprosy is highly contagious is conveyed in historical texts such as The Bible and mediaeval literature. Many people with leprosy (lepers) were isolated and/or shunned by society. However, now we know that leprosy is not easily transmitted from person to person unlike tuberculosis which is highly communicable. In fact, rapid spread of tuberculosis may have actually limited the spread of leprosy in the mediaeval populations. A third mycobacterial disease, Buruli Ulcer, is found in Africa and Australia. It appears to be contracted from water; however, like leprosy, the exact route of transmission is unknown. Mycobacterium ulcerans creates large, chronic lesion (bottom picture) that leaves infected people (often children under 15) disfigured.


Antonie van Leeuwenhoek is one of the historic figures often credited with inventing (or co-inventing ) the microscope as well as founding the science of microbiology. He made powerful glass lenses that enabled him to see single-celled organisms and conduct many experiments that ultimately convinced the scientific community that tiny living things existed-even though they were not visible to the naked eye. Leeuwenhoek called these microscopic organisms "animalcules", a term that is not widely used today other than in historic context. The story of Leeuwenhoek exemplifies science in several ways. First, it reminds us that scientific advancements are made after observations are tested methodically. Second, we see that sometimes unlikely scientists, like Leeuwenhoek, discover the unexpected.

Wednesday, December 16, 2009


Welcome to my blog about biological sciences. I hope that all who visit will find something here intellectually stimulating. I feel confident that over time this will evolve considerably. However, like living organisms, its future form may depend on various selective pressures. At this point, my goal is that it will be informative and instrumental in connecting visitors with the amazing science of biology.

"We will now discuss in a little more detail the Struggle for Existence."

-Charles Darwin