Monday, July 19, 2010

Anatomy Lab

Medical Meanderings 10 June 2009

Cutting Up ©

“He lived for others, he died for us.”
Common epigraph written on dissection tables circa 1900.

I clearly remember the first day of anatomy class, the second day of medical school in the summer of 1995. A large group of us, mostly new college graduates, stood nervously outside the anatomy lab doors. Although no one had told us to be quiet, we whispered with strangers who would soon be our lab partners. After a brief introduction from our professor regarding the layout of the anatomy lab, the textbook we’d be using, the location of the bathroom and so on, the big doors were opened and we filed in.

My three partners and I found our “humidor”: the metal table with two heavy, hinged doors in which the cadaver was kept. The doors were unlatched and carefully swung downward under the table. On the table was a white body bag with, obviously, a body in it.

When instructed, one of us (not me) unzipped the body bag, loosing a strong whiff of phenol and formalin preservative. The thin plastic was rolled back, and the petite 73-year old woman, whom we would come to know intimately, was exposed. She was on her back, naked, with face, hands and feet wrapped in moistened gauze to preserve them until that part of dissection—and to preserve our emotions for now. Her hair was shaved off, a fact that surprised me until I reflected on its necessity here. Her skin had an unnaturally firm, plastic look from the embalming process, which had also created many wrinkles as it dissolved some of her scarce body fat.

We started with her upper extremity—the arm. Two of us dissected each arm, one reading instructions and the other cutting. The first cuts were unnerving—we expected her to flinch, or bleed, or cry out, but of course skin is simply a material thing when life has left it. In a few days, we became comfortable learning to separate skin from muscle, ligament from tendon, nerve from artery. The details were overwhelming, the names foreign and functions complex. It didn’t take long to become so absorbed that we often forgot the arm we were exploring had hugged and waved goodbye.

From the upper extremities, we moved on to the chest and the back (which required the unexpectedly difficult task of turning her face-down). The head and neck required dissection of the face, another emotionally troubling task. Finally, we explored the pelvis and the lower extremities. Our cadaver was slowly disassembled into her component tissues, which were meticulously kept together. Finally, when we had learned all we could and passed the final examination, her 73-year old remains were cremated together, and given to her family for burial at a yearly ceremony held at the medical school.

Why, in this age of computer simulation, must doctors-to-be dissect human bodies? Because the feel of a nerve compared to an artery cannot be well-simulated. Because human beings vary more than books or programs can comprehend. Finally, because to help the living, the presence of death must not be as unnerving as it was to all of us uninitiated novices on that first day.


Medical Meanderings

Rub A Dub Dub (c)

In 1847, a young medical professor in Vienna, Austria, named Ignaz Semmelweis went to visit a sick friend. His friend, Jakob Kolletschka, was near death with a high fever, rapid pulse and sweats. Jakob had become sick soon after knicking one of his fingers while doing an autopsy and as Ignaz stood by his friend’s bed, watching him die decades before germ theory and antibiotics, Ignaz had a stunning insight: He had seen this disease before…in pregnant women.

Semmelweis had been troubled for years by the high death rate from “puerperal fever” in pregnant women in his hospital, where 13% of those admitted in labor died before hospital discharge. In a nearby obstetrical hospital run by midwives instead of physicians, the maternal death rate was only 2%. Now his friend Jakob had an illness very similar to puerperal fever from dissecting a dead body, and Semmelweis made a connection that would change medical practice forever.

Semmelweis had noticed that medical students would move from the autopsy room to the delivery room, wearing the same clothing and without washing their hands. On a hunch, he set up a policy: No one will be allowed to deliver a baby without first cleaning his hands in a chlorine solution. The death rate from puerperal fever on the labor and delivery ward dropped quickly to two percent.

Hand washing is the most basic weapon in the war against infectious disease. When done correctly, it can reduce the spread of many diseases. Unfortunately, it is rarely done correctly—in one study, 90% of hospital staff washed their hands for less than 10 seconds, instead of 15-30 seconds recommended by the Centers for Disease Control. Even in study situations, where people are being observed for compliance, only 40% of hospital staff washed their hands as they should have. Also, frequent hand washing is tough on the skin, causing changes in the types of germs present, and damaging the skin, possibly leading to a higher risk of transmitting infection.

Nowadays, alcohol hand rubs are becoming more widely accepted as the best way to clean hands. Alcohol hand rubs containing kill 90% or more of bacteria, viruses and fungi on the hands and reduce the risk of disease transmission from 92% with hand washing to 17%. Alcohol hand rubs work by breaking apart proteins in germs, and they work almost immediately. Also, they save time—whereas hand washing takes up to 30 seconds, the average alcohol hand rub is used in only 10 seconds. If you clean your hands five times a day, you will save 10 hours per year with a hand rub—that’s more than a full work day (or a good night’s sleep!).

Either way, by soap or by alcohol rub, in this season of colds, flu and strep, clean your hands early and often. Make Semmelweis proud. His insight, after all, eventually got him fired when the hospital administrator felt the policy change to be a criticism of his management. Science marches on, office politics doesn’t.

Ear Wax

Medical Meanderings 15 October 2008

Waxing Eloquent ©

If your head is wax, don’t walk in the sun.
Benjamin Franklin (1706-1790)

Ear wax is beautiful stuff. Medical types call ear wax “cerumen,” from the Latin word “cera,” meaning wax. Cerumen is a complicated mixture of secretions and debris produced by the outside third of our ear canals. The secretions include sebum, the same oily chemical that, when eaten by bacteria in our armpits, gives us the distinctive odor of locker rooms. Also, specific glands called ceruminous glands secrete the long chains of fat molecules that make ear wax so…waxy.

The sebum and wax mix with whatever passes by in the ear canal, including dead skin cells, bacteria living on our skin, water and occasional hairs. This mixture can range in texture from liquid to a rock-hard, and in color from a reddish-black to white. The characteristics of our cerumen depend on its specific composition and on how long it’s been sitting in the ear canal. The texture and color of our ear wax, however, doesn’t necessarily tell us much about how the ear canal is working.

The wax is moved outward from the ear canal by a lining of hair cells, by the movement of the tissues around our jaw joint, and by the normal growth of skin in the canal. The point of knowing this is: we do NOT need cotton-tipped swabs! The ear canal comes with standard equipment that moves the wax out, unless we do something (like sticking in a swab) that destroys the lining cells or packs the wax in more deeply or tightly. All we do with those swabs, toothpicks, paper clips or whatever else we stick in our ears is damage the system that would clean our ears out all on its own.

Cerumen has several important roles in keeping the ears healthy. First, it traps dust, skin, hair and insects that would otherwise plug up our ear canals in a few months, and moves that garbage out. Second, it absorbs water that would, if allowed to stay in the canal, form a home for bacteria to grow and infect us. Third, it is thought to have acted as an insect repellant back when our ancestors slept on the ground.

Getting rid of impacted ear wax is not something to try at home. Serious, sometimes permanent damage can be done to the ears during botched attempts to dig ear wax out. Leave it to the professionals, who have several methods of attacking this difficult problem. Drops that soften ear wax (e.g., mineral oil) are helpful. We will use cerumen spoons or curettes to carefully pull wax out. Water irrigation often works, and if all else fails, suction devices may work. There is no scientific evidence that “ear candling” is useful in removing ear wax, and it cannot be recommended.

The easiest way to maintain the health of your ear canals is to leave them alone. If it’s too late for that, then simply placing two drops of mineral oil in each ear once a week, occasional irrigation of the ear in the shower, and avoiding cotton swabs is all you need to do.

Saturday, July 17, 2010

Legionnaire's Disease

Medical Meanderings 14 October 2009

Philly Mystery (c)

“In solving a problem of this sort, the grand thing is to be able to reason backwards…but people do not practice it much.”
- Sherlock Holmes, in “A Study in Scarlet” (Sir Arthur Conan Doyle)

In July 1976, the Pennsylvania chapter of the American Legion, a non-political organization of military veterans, met in Philadelphia. Ten thousand men attended, but within days of returning from their convention, a dozen attendees were dead, and several others were hospitalized, due to a mysterious respiratory illness. Those affected were suffering with a rapidly-progressive pneumonia and fevers exceeding 107 degrees Fahrenheit.

The summer of 1976 was not very different from the summer of 2009. The country was primed with a fear of an infectious epidemic. The Ford administration was preparing to vaccinate the public against an unusual, spreading strain of influenza called “swine flu.” The media fed the fear, with Michael Crichton’s novel “The Andromeda Strain,” about the terrifying spread of a devastating pathogen, becoming a best seller. Then the news broke in early August about the new, fatal “Legion disease” in Pennsylvania, the cause of which had not been found.

Pennsylvania state health workers had initially responded to the epidemic by preparing for a medical disaster while reassuring the public that the crisis was under control. Help was soon requested, and the Communicable Disease Center (now the Centers for Disease Control and Prevention, or CDC) sent twenty federal disease investigators to assist dozens of state investigators. The CDC’s investigators were members of the Epidemiology Intelligence Service, the federal government’s “rapid response team” of physicians and public health scientists sent to do the detective work in any potential epidemic.

By the end of the epidemic, the disease had infected 221 Legionnaires and killed thirty-four. The medical investigators had spread across Pennsylvania, reviewing hospital records, attending autopsies and investigating the sites involved in the July convention. Initially, influenza was suspected, but none of the victims tested positive for the influenza virus. The investigators followed several other false leads, including the possibility that the Legionnaires had been exposed to a toxin, heavy metal or poison.

It took six months to identify the culprit of this epidemic, a newly-discovered bacterium that was named (in honor of this outbreak) Legionella pneumophilia (meaning “preferring the lungs”). Legionella prefers to live and grow in standing water. It had contaminated the plumbing within the convention hotel, then infected its victims through shower heads and faucets.

Legionnaire’s disease, as it is now known, is still relatively common, causing up to 10% of severe pneumonia with high fevers. Frighteningly, it has been found in up to 70% of hospital water systems in some geographic regions! However, we have diagnostic tests and antibiotics available to diagnose and treat Legionnaire’s disease that were not available in 1976. Nevertheless, there are lessons to be learned in the story of Legionnaire’s disease. The confusion and chaos of media-driven public fear can hinder progress and lead to irrational panic. On the other hand, the effectiveness of medical detective work and the scientific method is clear.

Locked-In Syndrome

Medical Meanderings 28 October 2009

The Horror ©

“A corpse with living eyes...”
- Alexander Dumas, “The Count of Monte Cristo”

Your eyes flutter open and slowly adjust. You hear voices in the distance, and something beeping in a regular rhythm. You try to sit up. No go. Okay, okay, you tell yourself--take it slow. To your right, just inside your peripheral vision, is a glowing monitor with colorful, squiggly lines and numbers, and a clicking box with a bag of water hanging above it. Toward your feet but above you, a television flickers. Directly in front of your face, a corrugated plastic tube seems to emerge from your face and stretch away somewhere. To your left, a sliding glass door beyond which uniformed men and women move briskly about. The answer comes: you’re in a hospital.

Again, you try to sit up without success or even movement. You try to raise your head. Nothing. Move your hand. Nothing. You try to call for help, to get someone’s attention. No movement, no sound. Then you realize you can blink, but you cannot move your eyes. You hear intermittent hissing of air through the tube which you now realize is in your throat, and the beeping of the monitor.

Soon, an older man in a long white coat and a young woman in bright scrubs enter your room. “Sad thing,” says the nurse. What happened? you want to say. “No obvious stroke on the CT scan, yet,” answers the doctor, “but sometimes big strokes can take awhile to show up.” A stroke? you think silently. I had a stroke? I don’t remember. “Well, at least the heart, liver, kidneys...everything seems healthy,” says the nurse. That sounds like good news, you think. “Yes, true. Hopefully some good will come of this,” the doctor answers. “I’ll go speak to the family about organ donation.”

What?! you want to scream. No, I’m here! But you cannot speak. Your eyelids can flutter, but you cannot speak, nor move, nor make a sound. You have indeed suffered a small stroke, but to a very important area of your brain. As a result, you have a rare neurological syndrome appropriately called locked-in syndrome.

Locked-in syndrome was first described in 1966. It is a state in which the connections between the higher regions of the brain (thinking and language) are severed from the regions, called the midbrain and pons, that carry impulses to the spinal cord. The result of this devastating injury is a patient who is fully conscious and awake, but unable to speak or move. It is vital that physician differentiate between locked-in syndrome and more common brain injury states such as coma (in which the patient is unmoving and unconscious) and persistent vegetative state (in which the patient can move but is unconscious). If not, an awake, thinking patient may end up an unwilling organ donor.

This Halloween, though, no need to fear that one day you will wake up unable to move or speak--appearing, essentially, to be brain dead. It wouldn’t, it couldn’t happen to you...right?

Protein Folding

Medical Meanderings 4 November 2009

Know When To Fold ‘Em ©

“The Universe is not only stranger than we imagine, it is stranger than we can imagine.”
J. B. S. Haldane (1892-1964)

If a mad scientist were to want to create a living human cell (and some non-mad scientists are working on this), he (women rarely become mad scientists) could not simply pour all the chemical ingredients into a blender and expect a good result. Most biological chemical reactions are so slow that they essentially don’t happen at all on their own. How do our own cells, then, manage to coax these molecules to react, thereby staying alive and keeping us alive?

The answer is the miracle of proteins. Every one of our cells contain millions of different proteins, which are the most versatile molecules known, the multi-function Swiss Army knives of biology. One class of proteins, called enzymes, are responsible for taking two different molecules and marrying them in the chemical reactions needed to maintain life. Enzymes are so efficient in this role as catalysts that they can increase the rate of a chemical reaction a billion- or trillion-fold. Each enzyme has a small pocket into which specific molecules fit snugly, like a plug into a socket, allowing the enzyme to do its chemical work.

What allows an enzyme to use this kind of key-in-lock specificity? Every protein is made of a long chain of building blocks called amino acids, which are linked together, like a string of pearls, in a particular order determined by a length of DNA. The chain of amino acids is called the “primary structure” of a protein. However, amino acids have positive and negative charges, so we can imagine a string of magnetic pearls which, far from hanging simply around a graceful neck, would stick to each other according to the rules of magnetic attraction. Amino acid chains tend to morph into spirals or crinkled sheets called the protein’s “secondary structure.” The sheets and spirals then bend sharply, stick together, fold into each other. All this folding and bending results in the protein’s “tertiary structure,” a specific three-dimensional shape, more complicated than paper origami, which determines the function of the protein enzyme.

Now we can see why a change (mutation) in a particular gene might have major effects in the body. The DNA sequence of the gene decides the order of amino acid building blocks, but if even a single pearl is changed, the string folds up in a completely different way, and that enzyme will function very differently. The lock changes, and maybe the key fits better, maybe it doesn’t fit at all. Depending on the protein, the change can be helpful, neutral or catastrophic.

Scientists are beginning to better understand the effects of protein folding on the development of embryos, various diseases (such as “mad cow” disease and sickle cell anemia) and the overall course evolution has taken. The complicated path from gene to amino acid to protein folding is becoming clearer, and it will be exciting to see how the future...unfolds.

Friday, July 16, 2010

Medical Meanderings is back!

After an eight-month hiatus due to a lair location change, Meanderings is back! The Committee on Meanderings Authorship (comprising the world's top literary and medical minds) and distinguished Editorial Board (members of which have sworn an oath of secrecy and anonymity) cannot guarantee that Medical Meanderings will be released weekly, but we will do our best to provide the world with interesting, entertaining and factually accurate reflections on an intermittent basis. Enjoy, Dear Readers!

P.S. To get the proverbial ball rolling, the CMA has posted a few oldies but goodies.