Run Silent, Run Deep

After reading Mark's post on the physiology of breath hold diving, I wanted to post this picture of the Ama, free-dive (breath-hold) pearl divers in Japan. Both male and female Ama can be found in various fishing villages in Japan where they harvest pearls and abalone. There is a comparable community of divers (females only) in Korea, the Hae-Nyu.

Deep-sea breath divers- physiological response

In highschool I ran cross country. And during exercises I was left to ponder simple things, like breathing. In my experience, a trained ability to focus on breathing patterns aids in exercising efficiency. Well, today in class I was thinking about deep sea divers and whales and mammals that can stay underwater for long periods of time. The first connection is to Japanease and Korean Pearl divers who regularly descend 20-30 meters to collect pearls.

In researching I found that a component of this physiological training, occurs in (probably) all mammals, certainly in humans, whether trained or not. Apparently, submerging the face in cold water and holding your breath (self-induced apnea) causes body tissue to more redily convert to anaerobic respiration, thereby drawing less from the oxygen reserve in the lungs, and allowing a longer breath. The key factor here is the cold-water induced anaerobics which is not a need based cellular cycle (regular anaerobics are induced in response to higher O2 demand).
http://jap.physiology.org/cgi/content/full/93/3/882 From the Journal of Applied Physiology


What i was really looking for was information on the Diving reflex, something which reduces bloodflow to nonessential organs for a short period of time. the stomach, spleen, and liver are nearly entirely shut down to reduce the heart's required output. only the essential organs are supplied, thereby reducing the heart rate as well (bradycardia or brachacardia). This permits the mammallian body to survive effectively on only one breath for a longer period of time. With training, deep sea divers can enter bradycardia almost at will.
"In 2002, free-diving champion Mandy-Rae Cruikshank set a women’s world record for static apnea of 6 minutes 13 seconds (the men’s record, set in 2001 by Scott Campbell, is 6 minutes 45 seconds)." http://advan.physiology.org/cgi/content/full/27/3/130SIMULATED HUMAN DIVING AND HEART RATE: MAKING THE MOST OF THE DIVING RESPONSE AS A LABORATORY EXERCISE Sara M. Hiebert1 and Elliot Burch2



As an aside, mental arithmetic speeds up the transfer into submerged bradycardia. Prose, however, has no affect.
"Attenuation of the diving reflex in man by mental stimulation." Ross A, Steptoe A.

Living with pain

Something that I have been curious about lately is the news with Merck, the company that voluntarily withdrew Vioxx, a non-steriodal anti-inflammatory drug. My grandmother used it to deal with the pain of arthritis, and I took it after a knee reconstruction surgery 6 years ago.

Vioxx was taken off the market in September 2004 because of accusations Merck hid evidence that the drug may increase the risk of heart attack and stroke in those using the drug chronically. Many drugs list "possible heart attack and stroke" as side effects, so I wondered why Merck couldn't continue releasing the drug, just with an additional warning. Since the risk of CV problems are low, most elderly living with chronic arthritis pain consider the benefits of Vioxx to outweigh its risks. Another benefit of Vioxx is that it shows less risk of GI and intenstinal problems, unlike other pain medications.

From the information I gathered through Merck's website, a study was done to examine the effects of CV problems associated with their drug. Some myocardial infarctions were left out of the data, and questions came up about the drug. To save themselves from huge lawsuits, Merck voluntarily withdrew the drug. Earily in February they won a case in which they were being sued by the family of a Florida man who had died from a heart attack. Merck was able to prove that the man had only been taking Vioxx for a month and had several risk factors for a heart attack, including a clogged artery. The findings seem to show that short-term use of the drug does not increase CV risks.

With all of the pending lawsuits, it looks as though Vioxx is gone from the market for good. Because CV problems are so common, families are finding it much easier to blame Merck and Vioxx, rather than a patient's medical/dietary problems. Sad news for those who haven't been able to find another effective chronic pain killer.

SIDS and Living at a High Altitude

Recently we were discussing SIDS, and how the instigating factor of SIDS is sleep apnea due to hypoxia. Well I couldn't help but ask the question "Since people at high altitudes live in low oxygen, are they suffering from more instances of SIDS?" And our esteemed Dr. Wasser told me to find out. So here is my finding. I've cut and pasted the Abstract of the article and the link to the full one, if you so deem it worthy of your time to pursue.

"Living at high altitude and risk of sudden infant death syndrome
OBJECTIVE To investigate the association between altitude of residence and risk of sudden infant death syndrome (SIDS).METHODSA retrospective, case control study in the Tyrol, Austria enrolled 99 infants with SIDS occurring between 1984 and 1994, and 136 randomly selected control cases. Data on pregnancy, delivery, child care practice, and sociodemographic characteristics including altitude of residence were collected with a standardised questionnaire.
RESULTS The risk of SIDS increased gradually with increasing altitude of residence. This relation remained independently significant when the analysis was adjusted for gestational age, birth weight, prenatal care, mother's age at delivery, educational level of parents, and cigarette smoking during pregnancy. The prone sleeping position emerged as an obligatory cofactor in this association. In the whole of Austria, a similar trend of association emerged between the average altitudes in the 99 political counties and the rates of SIDS.
CONCLUSIONS This study identified altitude of residence as a significant risk predictor of SIDS, primarily in combination with the prone sleeping position. Respiratory disturbances, reduced oxygen saturation, and lower temperatures at high altitude might explain this association.(Arch Dis Child 1998;79:506-509)"

http://adc.bmjjournals.com/cgi/content/full/79/6/506

And I believe that answers my question.

Have a great day!

Unintelligent Design

After Dr. Wasser's comments on Intelligent Design the other day and the latest trend of posting news stories to this blog, I thought I might add my two cents to the penny tray.

http://www.discover.com/issues/mar-06/cover/?page=1

The cover story on this month's Discover magazine is about a virus that's large enough to be seen with a light microscope and with more genes than some species of bacteria. Known as a mimivirus, this virus has genes for DNA repair enzymes and protein translation, behaviors that were considered unique amongst cellular organisms. Now theories are being presented in which stabalized viruses within prokaryotic bacteria were the precursors to eukaryotic cells.

Some interesting points from the article:

• People actually have more retroviral DNA in their cells than "human" DNA.
• There exist "satellites" which are viruses that replicate inside other viruses that are replicating within cells.
• Or viroids which are viruses without a protein coat. These are free-floating strands of RNA that don't code for anything, yet somehow cause disease.
  

Super Bowl Ads

Do those funny Super Bowl commercials actually work? Some scientists at UCLA used functional magnetic resonance imaging to measure brain responses in a group of subjects while they watched the Super Bowl ads. What they discovered is a strong disconnect between what people say they liked and what their brain activity suggests. There were cases where ads elicited very little response in emotional, reward-related, and empathy-related areas of the brain when the subjects response to the ad would suggest opposite results. http://edge.org/3rd_culture/iacoboni06/iacoboni06_index.html

Hutchinson-Gilford Progeria ("premature aging syndrome")

The National Human Genome Research Insttitue (NHGRI) of the National Institutes of Health (NIH) is currently recruiting patients for an observational clinical study of Hutchinson-Gilford progeria (premature "aging" syndrome). Check out their website at:

http://www.clinicaltrials.gov/ct/gui/show/NCT00094393

Live to sleep, sleep to live!

In response to Kyle’s post on a Vietnamese man who, apparently, hadn’t slept in 30 years, I ran a Google search on “sleep disorders” and (among other things) turned up some information on Fatal Familial Insomnia (FFI).

Here is what Wikipedia has to say about FFI:

Fatal familial insomnia (FFI) is a very rare, autosomal dominant inherited, disease of the brain. It is caused by a mutation in a protein called prion protein (PrP): asparagine-178 is replaced by aspartic acid. The mutation changes the shape of PrP so that it becomes a prion and makes other, normal PrP molecules change to the abnormal shape. This causes amyloid plaques in the thalamus, the region of the brain responsible for regulation of sleep patterns. The dysfunction of the thalamus first results in insomnia, which progresses to more serious problems over several years. The age of onset is variable ranging from 30 to 60. Death usually occurs within 3 years of onset. The presentation of the disease varies considerably from person to person, even among patients from within the same family. Common symptoms and signs include:

• intractable insomnia
• dysfunction of the autonomic system - causing hyperthermia, hypertension, tachycardia, tachypnea and hyperhydrosis
• dementia
• motor paralysis.

There are other "prion diseases" (TSEs) with different symptoms, such as Creutzfeldt-Jakob disease (CJD) and new variant CJD (vCJD) in humans, bovine spongiform encephalopathy (BSE) in cows, and chronic wasting disease in American deer and American elk (in some areas of the Rocky Mountains). FFI, as with other prion related diseases, is ultimately fatal and incurable. Hopes rest on the so far unsuccessful gene therapy and possibly drug development.

And here’s a link to more detailed information on the condition at the John Hopkins University “Online Mendelian Inheritance in Man” database:

http://www.ncbi.nlm.nih.gov/entrez/dispomim.cgi?id=600072

Prolonged sleeplessness generally leads to various somatic and psychological disorders and even death. I suspect the man in the article cited by Kyle is engaging in “microsleep”, short bursts of sleep interspersed between long wakefulness periods. It is not really credible that the man has been truly “sleepless” continuously for 30 years.

Even “fragmented” sleep, i.e. periods of sleep interrupted at irregular intervals throughout the night can leave a person in good condition to perform physical work. I was a subject in sleep deprivation experiments while a graduate student at Indiana University and although fragmented sleep was annoying, my performance on the tread-mill tests the following day was comparable to my control performance after a normal nights sleep.

Real world VIZR? "Make it so!"

Andrew's post on bioengineering advances in vision enhancement reminded me that, some time ago, I found a company website that was marketing vision enhancement devices for people with macular degeneration and other vision disorders. These folks, "Enhanced Vision Inc." actually sell a product they call "JORDY" (after the eponymous Lt. Commander Geordi LaForge from Star Trek--The Next Generation). Here's a photo. I believe this device simply magnifies the image rather than doing something really cool like allowing a person to see "new", previously undetectable colors, but I like the fact that the corporate execs were comfortable enough to name the thing, "JORDY"! Here's a link to their website:

http://www.enhancedvision.com/

Geordi La Forge's eyes

Howdy fellow bioengineers! I'm a little late... I missed the memo that we were blogging again this semester.

Something I read a while back (I don't remember where, or I'd list the reference - you might be able to google it) has really boggled my mind. It's about work on "replacing" the eyes. Obviously what we see is the interpretation of signals from the eyes given to it by the optic nerve. The article I read was about how if prosthetic eyes bypass the optic nerve and go directly to the brain, it might provide some semblance of vision.

Here's where it gets weird. Cameras and sensing equipment can see more wavelengths of light than a natural human eye. So if your prosthetic eye picks up ultraviolet and feeds it into your brain, what will you see? Some speculate that you will "see" a new color - your brain being forced to create a new interpretation for information. You might be able to see WHOLE NEW COLORS that we can't even imagine!

There are numerous other questions about what that kind of sight might entail. Would you be constantly overwhelmed by massive input until you flipped the "off" switch for your eyes? If your eyes could pick up lower quantities of light, would that essentially make lights obsolete because everyone can see in the dark?

Prosthetic eyes- one of the many reasons I love being a biomedical engineer.

Brain Freeze

Ice cream headaches are a common occurence for those slushy lovers out there. This post is for you. Wikipedia describes frozen brain syndrome as, "A reaction triggered by a cold substance consumed coming into contact with the roof of the mouth". It elaborates further describing how the cold stimulus irritates the specific nerves in the region of sphenopalatine ganglia. This causes them to spasm, then the nerves cause blood vessels in the brain to dilate. An article by Joseph Hulihan described the area, "The pain is usually located in the midfrontal area, but can be unilateral in the temporal, frontal, or retro-orbital region". The acute headache occurs as a result of this exaggerated dilation. Wikipedia then mentioned that this is similar to the headache someone might feel after taking a vasodilator like Nitroglycerin or Viagra. The Hulihan site further mentioned that ice cream headaches only happen on hot days, and their seems to be inconsistencies as to whether ice cream headaches are more or less common in chronic migraine sufferers.

These are the sites I found my info on.
Wikipedia
Joseph Hulihan site

Prematurely Aging Kids

I recently came across an article about children with Hutchinson-Gilford progeria syndrome(HGPS). It causes the rapid aging of kids. This disease is very rare, occurring to only 50 children worldwide. I learned that these kids age seven times the normal rate. Their mental growth is the same to other children their age, and their physical features include dwarfism, wrinkled skin, baldness and a pinched nose. Its symptoms are depressing for me to state, because they include osteoporosis, hair loss, and atherosclerosis; elderly problems. Because of the symptoms listed, they die by early childhood. A research team discovered while experimenting on mice, that a drug used for cancer can delay the symptoms of HGPS, and increase the survival of the mice that carry a similar disease. I hope that people will continue with their research to help these children, regardless of its rarity.

http://www.sciencemag.org/cgi/content/full/311/5763/934a

Human Anomaly

I came acrosst his article that describes a man who supposedly hasn't slept for 33 years, without serious medical complications. I wonder how his immune system and brain have compensated for this lack of rest. I have a couple of questions about this: How many people would love to have this condition, to not be tired enough to sleep? and is this legitimate, can a person really go without sleep?

http://www.thanhniennews.com/features/?catid=10&newsid=12673

Week 1

Bioengineers at Work - Well I decided to break the ice and post my first entry to the blog. It is the first week we have really worked on the device design project. I am happy to say I am a proud member of Ewok-502 and we have been assigned the neonate icmo. Our first virtual meeting is tommorrow with dr. wasser so I looked a few things up today. I found the diameter of an intubation tube for a preemie to kind of give an idea of how big the thoat and possible air intake can be. In my head I have a few ideas on the way i imagine the device will look however getting it to work will be a challenge. I am optomistic that with my team we will develop a really awesome yet practical device, and having experience volunteering in a neonatal intensive care unit I really understand and appreciate the reasoning behind this project.

Bioengineers at Work--a new beginning!

The time has come for all of my Physiology for Bioengineering students to contribute to what's out there in the Blogosphere! This semester, all of you will be required to post to the blog at least once per week. I am interested in your observations and comments on this semester's device design project, on the "science news based active learning" assignments and class sessions, and on anything else you would like to comment on--provided it has to do with physiology, medicine, or bioengineering.

Now it is possible that you have been considering the pedagogic innovations we are trying out in our course this semester and have thought, "Well, after last semester's intense training, I'm not scared!". In the immortal words of Master Joda, "You will be...you will be!"