Thursday, January 24, 2008

Mitochondrial Diseases

Yes there are diseases due to malfunctioning mitochondria. You can find an introduction here at the United Mitochondrial Disease Foundation. Many of these diseases are due to mutations in the mitochondrial DNA.

If you are really interested I found a free full text article about mitochondria and mitochondrial diseases here (but you have to register).

Healing Powers of Hyperbaric Oxygen

Several diseases can be treated with hyperbaric oxygen. Read about some of them here at the Medical College of Wisconsin.

As for the use of hyperbaric oxygen therapy in cancer, there doesn't seem to be any firm evidence that it is useful. There is a fair bit of literature on the subject but I couldn't find any clinical trials that show the effectiveness of HBO treatment on cancer.


Go here to see examples of coagulative necrosis and resulting infarcts both at the gross level and histological level. Keep clicking the 'right' arrow to see more examples. What is the most common cause of coagulative necrosis?

Examples of liquefactive necrosis can be seen starting here. Notice the photo of the macrophages cleaning up debris from an area of liquefactive necrosis in the brain.

Examples of fat necrosis start here.

Next is, you got it, the cheesy caseous necrosis seen in TB infected lung.

The Mycobacteria need to create these extensive areas of necrosis so they can be coughed out of the lungs and passed on to another individual.

Gangrene is next. Don't click on the link if you are feeling ill. The photo is of disembodied toes. We all know what can happen if you get frostbite.

Fibrinoid necrosis in hypertension.

Remember we talked about accumulation of abnormally folded proteins. Check out this photo of amyloid accumulation.

Then there is aging. Wear and tear (growing old) results in the accumulation of lipochrome in the liver. This is cellular debris that is sequestered within the cytoplasm.

Cell Adaptation

Here are some examples of alterations in cell growth.

You can read more detail about muscle atrophy here.

Have you got that going problem? Maybe it's a growing problem. Benign prostate hyperplasia cartoon. Read more about BPH here.

Learn more about metaplasia here.

An example of cervical dysplasia. Keep clicking for more examples of dysplasia.

Here the entire epithelium is dysplastic so you have a full blown neoplasm. The basement membrane is intact however, so the cancer is not yet malignant.


More than you will ever want or need to know about apoptosis at this good website.

I borrowed this picture from the above website. It compares the process of apoptosis and necrosis.

You can read about the p53 tumor suppressor gene, apoptosis and prostate cancer here. We will cover this in more detail when we discuss neoplasms.

Tuesday, January 22, 2008

Guinea Worm and the Medical Practice Symbol

I have mentioned that I am reading "Parasite Rex" by Carl Zimmer. The book is just as I expected. Wonderfully written, scary stories and anecdotes about parasites. I especially like his discussion of how the term "parasite" arose.
The word literally means "beside food," and the Greeks originally had something different in mind when they used it, referring to officials who served at temple feasts. At some point the word slipped its etymological harness and came to mean a hanger-on, someone who could get the occasional meal from a nobelman by pleasing him with good conversation....
But that is neither here nor there. Let's discuss guinea worm infection and its possible association with the symbol of medical practice....the Caduceus. The study of parasitology is filled with stories concerning history and especially biblical references.

Guinea worm, or Dracunculus medinensis, is a roundworm found in India, West and Central Africa and parts of the Middle East. The worms are found in the subcutaneous tissues of humans and the female worm can be over 30 inches in length. You become infected with guinea worm by drinking water that is contaminated with small, freshwater crustaceans that are themselves infected with guinea worm larvae. (Cyclops).

When the crustacean is consumed in contaminated drinking water, the guinea worm larvae in the Cyclops is released and makes its way through the intestinal wall, crosses the abdominal mesentaries, penetrates the abdominal muscles and make their way to the subcutaneous tissues. Fertilized females release their live larvae by penetrating the skin about a year after infection. Infected individuals often wind the body of the emerging female around a small stick so as to collect the entire adult worm rather than breaking it off in the body.

Obviously, the way to prevent this infection is to provide a clean, uncontaminated, source of drinking water. Also, the live larvae of the adult female need to be released into fresh water in order to find a Cyclops to infect as an intermediate host. So please do not go swimming or wading in fresh water if you find yourself with a female guinea worm emerging from your body.

Now, what you ask does this have to do with the symbol of medical practice? Well, you need to open your bible to Numbers 21:6-9:
And the Lord sent fiery serpents among the people, and they bit the people; and much people of Israel died.

Therefore the people came to Moses and said, We have sinned, for we have spoken against the Lord, and against thee; pray unto the Lord, that he take away the serpents from us. And Moses prayed for the people.

And the Lord said unto Moses, Make thee a fiery serpent, and set it upon a pole; and it shall come to pass, that every one that is bitten, when he looketh upon it, shall live.

And Moses made a serpent of brass, and put it upon a pole; and it came to pass, that if a serpent had bitten any man, when he beheld the serpent of brass, he lived.
Here we have talk of a serpent on a pole. Guinea worm, by the way, causes intense pain (like fire) when it emerges from a blister on an arm or leg.

Where Zimmer gets it wrong is stating that "But it may be that that person's invention was remembered in the symbol of medicine, known as the caduceus: two serpents wound around a staff." [Chapt. 1, pg. 2]

Actually, the symbol of medicine is not the winged staff with two serpents. That would be the "Caduceus of Mercury" or the "Karykeion of Hermes". This is actually a symbol of commerce.

The actual symbol of medicine is the Staff of Asclepius. A staff, or stick, with a single snake wrapped around it. You can find all you want to know about the difference between a caduceus and the staff of Asclepius here at the website of New Zealand physician Dr. Blayney.

Why is the caduceus a symbol of medicine in the USA? Blame it on the US Army Medical Corps.

Prefixes and Suffixes


a - without or not

an - without

angio - vessel

arthro - joint

brady - slow

dys - difficult or bad

homeo - similar

hyper - above or excessive

hypo - deficiency or beneath

inter - between

intra - within

mal - bad

micro - small

mega - large

necro - death

neo - new

para - beside

peri - around

osteo - bone

para - beside

peri - around

phleb - vein

poly - many

pro - before

pseudo - false

pyo - pus

steno - narrow, compressed

syn - together with

tachy - rapid


algia - pain

emia - blood

genesis - generation of

iasis - a process, especially a morbid one

ism - condition

itis - inflammation of the part named

lysis - to dissolve

megaly - large

oma - tumor

osis - full of

pathy - disease

penia - poverty, a deficiency

plasia - to form

plegia - a paralyzed state

ptosis - downward displacement

sclerosis - hardening

stasis - standing still

trophy - nourish

Some Terms

Etiology. The cause of disease. Disease is either caused by genetic or acquired factors. Disease results from cell injury.

Pathogenesis. How the disease develops. The sequence of events or physiologic processes that result in disease.

What is disease? One definition is: An interruption, cessation, or disorder of body functions, systems, or organs. Another is the pattern of response of a living organism to some form of injury with a resultant alteration in normal function.

For a long list of diseases and information about them go to the disease list at CDC.

Injury. Damage or harm caused to the structure or function of the body.

Infection. A detrimental colonization of a host organism by a foreign species.

Angiogenesis. The process of blood vessel formation.

Apoptosis. Programmed cell death. Usually a normal biological function.

Atherosclerosis. A disease of arteries characterized by chronic inflammation, scarring and cholesterol deposits in large and medium-sized arteries.

Atrophy. A shrinkage in the size of cells, organs and tissues.

Dysplasia. An abnormal development of a body tissue.

Embolism. Obstruction of a blood vessel by an abnormal mass formed elsewhere in the circulation and transported to its point of impaction.

Fibrosis. The formation of fibrous tissuek, usually as a reaction to chronic inflammation.

Gangrene. Combination of tissue necrosis with infection.

Homeostasis. The maintenance of a steady state in respect of physiologic function in the face of environmental variation.

Hyperplasia. An increase in the number of cells in a given population.

Hypertrophy. An increase in the size of individual cells usually due to increase workload.

Hypoxia. A reduction in the supply of oxygen.

Impaction. The lodgement of some abnormal mass in a hollow muscular tube causing blockage of the lumen.

Infarct. An area of tissue necrosis caused by a lack of blood supply to the affected region.

Ischemia. The pathophysiologic state in which the blood supply of an organ or tissue is reduced below its metabolic needs.

Metaplasia. A change in a cell population from one fully differentiated form to another fully differentiated form.

Necrosis. The death of a tissue within a circumscribed area.

Thrombosis. The formation of an abnormal intravascular mass from the constituents of flowing blood.

Thrombus. An abnomal intravascular mass formed from the constituents of flowing blood.

A Short History of Pathology

Cornelius Celsus (30 BC - 38 AD) describes clinical features of inflammation. Calor, rubor, dolor, tumor.

Galen (131 - 201 AD) a physician to the Roman gladiators. He didn't dissect human cadavors but Galen's great powers of observation allowed him to study, classify, and record anatomic and pathologic observations. Some of his observations, like the crab-like growth of cancers, were correct.

Leonardo da Vinci (1452 -1519) was one of the first to dissect humans in the quest for answers about the human form.

Andreas Vesalius (1514 - 1564) dissected humans and published a book De Humani Corporis Fabrica, 1543. His drawings of the human skeleton are especially noted for their detail and artestry.

More images and pages of his book can be seen here.

Antonio Benivieni (1443 - 1502) is credited for performing the first autopsies on humans to determine the cause of death. Not much is known about Benivieni's life.

Anatomy as a subject of study became acceptible in the 17th century.

Marie-Francois-Xavier Bichat (1771 - 1802), a French physcian was one of the first 'modern' pathologists and is considered by many to be the father of histology and pathology.

John Hunter (1728 - 1793), an Englishman who devised a method for preserving diseased tissues so they could be studied in the future.

Carl Rokitansky (1804 – 1878) is said to have performed over 20,000 autopsies and oversaw the performance of 60,000 more. He made important observations concerning multiple sclerosis.

Rudolf Virchow (1821 - 1905), used the microscope to learn that diseases arise from alterations within tissues and cells.

Julius Cohnheim (1839–1884), Virchow's student, devised experiments to study inflammation as it happened rather than after the tissue was dead. The Father of Experimental Pathology.

Some information about these pathologists was obtained here.