Pharm phun

Two drugs, almost identical molecular structure, very different actions.

Before there was viagra, there was alprostadil. This is a prostaglandin (PGE 1). It is given by penile injection to cause vasodilation and erection. Ouch...

Another drug, dinoprostone, another prostaglandin (PGE 2), is administered vaginally. Given in early pregnancy, it is abortifacient, meaning it causes an abortion. Given in late pregnancy, it causes uterine muscle contraction and induction of labor.

Two drugs, almost identical chemical structure, very different results. Interesting.

Long awaited return

I must apologize to those who have been checking this blog daily only to find that they will not get their random medical fact fix. But alas, i return, only to issue a grave warning.

Haemophilus influenza - this small gram negative coccobacilli has all but been eliminated from the united states. But, like so many other diseases, this one to tends to prey on those other countries unalbe to afford vaccinations. The full name, Haemophilus influenzae biogroup aegyptius, is alive and well in South America. It causes Brazilian purpuric fever. Symptoms begin with conjunctivitis that develops into a fever, petechiae (small pinpoint bleeds), then purpura (larger hemorrhages) and eventually septic shock. This has a high mortality rate.

So, if you happen to know three lost travelers making their way through South America, do tell them to stay clear of the dreaded Hemophilus influenza biogroup aegyptius!!!

sebatical

neuroscience is behind me, and the purple mountain majesty is before me. i'll be taking a week off, so for those of you who check the blog first thing in the morning, you'll have to find something else to get yourself out of bed.

peace!

cataplexy

cataplexy (a form of narcolepsy) is a rediculus disorder i thought i would share with you. symptoms: you fall asleep when you get really excited. got nothing to do for the next few minutes? check these out.

http://www.youtube.com/watch?v=wN1_yS6_5T4&NR=1

http://www.youtube.com/watch?v=XyzeCiW-nn0&NR=1

http://www.youtube.com/watch?v=HOkckq9pfoE&NR=1

so, as most of you guessed, the safest place to have a heart attack is not in a hospital. in fact, its one of the most dangerous. why? so many people are trained in CPR and there are AED's hung in every public place (try to find it next time you go the the grocery store, i'll bet they have one). it actually matters more on how many people are around to see you go down that relates to how likely you are to survive.
the rank:
best place to have a heart attack - casino, then airport (60% survival) then mall, then hospital (only 20% chance of survival).

its because your usually all alone in your room and the nurse is attending to many patients and only checks in once in a while.

I have some pretty smart readers.

MI Survival Quiz

Today I am giving you a quiz. I only see it as fair. I have to take them, and would like you to experience the joy... Good luck.

(Quiz is on the right)

hierarchy

there is a hierarchy in medicine. at the top of this pyramid are the neurosurgeons who think they are God. its because, as far as our medical abilities are concerned, they pretty much are. they push the limits of medicine and save lives that no one else can.

the other day we had a lecture from a neurosurgeon. he said something that will stick with me for the rest of my medical career.

"The biggest mistake in medicine is not listening to the mom."
-Dr. Letarte M.D. Neurosurgeon

drug origins

i'm constantly amazed where drugs come from. some are from plants, some are from animals, some are made in a labratory, some are found in nature and then modified in labratories.

this one has a pretty cool history

Ergotamine: this is a medicine used to abort migraines once they have started. it is a partial agonist at 5-HT (serotonin) receptors, causing vasoconstriciton and suppression of meningeal nociceptive pathways.

History: derived from a fungus called claviceps purpurea, which infects grain. People would eat this invected grain and have prolonged vasospasms, gangrene, paresthesias, and spontaneous aborthions. It was known as St. Anthony's fire, because for relief of the disease, people would pilgramage to St. Anthony's shrine. In reality, they would be healed from this because they were eating a fungus-free diet on their pilgramige.

Other drug derivations.

Opioids: Poppy seeds. This group includes morphine, codine, and heroin.
Atropine: an antimuscarinic drug used to decrease the parasympathetic nervous system. it is derived from the plant Atropa belladonna. This plant got its name because ectracts from the plant were used by Italian women to dilate their pupils, a very attractive trait (apparently). I know thats the first thing i look at when i see a beautiful woman... her pupil size. mmm... i love me some big pupils... big, bilateral, dilated pupils... ok, i better stop. im going to get in trouble for this one.

MSG

MSG? yeah, that flavor enhancer in your panda express known as monosodium glutamate. it actually kills cells in the arcuate nucleus in your hypothalamus. so what? well, turns out the hypothalamus does a lot. that nucleus specifically controls feeding behavior. so, when you kill those cells, you eat a lot, which leads to obesity. hum... so that is why i want to eat so much orange chicken and fried rice.

other neclei in the hypothalamus.
preoptic n. controls temperature.
posterior hypothalamus n. controls shivering and autonomics
suprachiasmatic n. controls your circadian rhythm (entrained by light, taking the retinothalamic pathway
dorsal medial n. also contributes to circadian rhythm but is entrained by feeding schedule
lateral hypothalamus releases orexin which makes you eat. it receives signals from the arcuate n. in form of neuropeptide Y and AGRP which are orexic (they make you want to eat) as opposed to anorexic ( you know what this means).

Kluver-Bucy Syndrome

jeff, this one is for you.

crazy disease with absurd symptoms, do read on.

this is a disease caused by a bilateral lesion in the temporal lobe, including the amygdala, temporal neocortex, olfactory cortex and hippocampus.

symptoms:

visual agnosia: all objects, living or not, familiar or not, food or feces, are approached and compulsively examed, often orally

Oral tendencies: everything is compulsively put into the mouth, licked, chewed and smelled

Loss of fear and anger

Hypersexuality: male monkeys with this disease display frequent erections and copulate with other monkeys (male or female) whenever possible.

examples of animals with kluver-bucy syndrome

the blind can see!

no, i'm not jesus, nor did i discover a new way to heal the blind. they actually can see. let me explain.

the world around us enters the eye as light, falls on the retina then travels in the optic nerve, the optic chiasm (where it gets all switched up) and then the optic tract to the Lateral Geniculate. from here, the visual information is sent through the optic radiation (inferior visual field via the geniculocalcarine tract and the superior visual field via Meyer's loop) to the occipital lobe of the brain.

if someone has an infarct of the posterior cerebral artery affecting the occipital lobe (the part of our brain that processes visual information) then they have cortical blindness. they can't see anything.

however, if you throw a ball at their head, they will duck, or catch it! trust me, i tried it. how?

remember the lateral geniculate i mentioned? well, not only does it send off the optic radiation to the occipital lobe, but it also sends fibers through the brachium of the superior colliculus to the superior colliculus (SC). from the SC originates the tectospinal tract. this is the tract (or group of nerves) that allows us to respond to a stimuli such as a ball thrown at our head.

in the blind person, they have a lesion that occurs after this branch to the superior colliculus. thus, they duck the ball, or worse, catch it and throw it back! another way to test this phenomenon is to hold a pen in front of the blind person. 9 times out of 10 they will be able to tell you if it is pointing up or down.

so, im not advicating that you throw things at blind people, but i thought i would share this very cool bit of info with you. hope you enjoyed!

random facts

your brain grows! if you practice a certain motion, the part of your brain that corresponds to that motion actually becomes thicker. with all of the complex movements that i practice each day, think of how thick my brain must be!

spacticity is a upper motor neuron sign characterised by increased tone, unequally between muscles, especially anti-gravity muscles: upper limb: flexors > extensors. lower limb, extensors > flexors.
rigidity is an increased tone seen equally in flexors and extensors. its caused by a lesion in the extrapyramidal system (basal ganglion)

what is a Bloodgood cyst? the same thing as a cyctic mastitis, adenosis, bluedomed cyst, and Schimmelbusch disease. it is a cystic mastopathy found on the breast. (breast exams begin tomorrow)

muscle relaxants, receptor reserve and lethal injection

there are two types of neuromuscular relaxants (that i have learned, there are probably many more). one kind inhibits your muscles from being activated but depolarization occurs, one kind depolarizaiton does not occur.

Non-depolarization: (pancuronium, tubocurarine, vecuronium, mivacurium, rocuronium) this type works by binding to the nicotinic receptors and not allowing acetylcholine to bind. this drug demonstrates competitive, reversible binding.

depolarizing drugs: (ie succinylcholine) allows the muscle cell to be depolarized, but doesn't allow the sodium channels to be reactivated, and thus you get no more muscle contraction.

receptor reserve: this is a bit of a dificult concept. a ligand (drug) binds to its specific receptor at its target tissue. sometimes, to get a maximal effect, you dont have to have a drug binding to all the receptors. so, say you have a complete effect of the drug with only 80% of the receptors bound to drug, you have a receptor reserve (receptors unbound).

drugs like non-depolarizing neuromuscular relaxants bind to the receptor and inhibit a normal physiologic action, muscle contraction. however, if enough acetylcholine is present, you can still get muscle contraction.

diferent tissues have diferent levels of receptor reserve, and for very good reason. small fine muscles (facial expression) have the lowest reserve, so they will be affected first by these drugs. large muscles (leg and trunk muscles) have medium receptor reserve, so they will be affected next. lastly comes the diaphragm (the muscule that allows you to breath). it has the highest receptor reserve, meaning it will be the last one to be affected by this drug, which interestingly enough comes from a south american plant used by indians on the tips of arrows to kill animals. so, God designed our bodies to preserve life.

lethal injection: tubocurarine, a non-depolarizing muscle relaxant with a duration of action greater than 60 min and metabolized by the liver and kidney, is used for lethal injection. it paralizes your diaphram and you sufficate. yikes!

sorry for ending on such a depressing note. on friday we started the beautiful day with a lecture on death and the process of dying. happy thoughts...

whoever invented drug names should be shot.

mirror neuron system

i must appologize to those who check my blog regularly. we had a test last week, so i took the rest of the week off, sort of, and didn't really learn a whole lot. this last weekend i was rock climbing in red river gorge. so, today marks my return to the books.

what i learned today... pretty amazing, your going to like this one. so when we move our hand, or feel pain in our leg, a certain part of our brain is activated. there are parts of our brain devoted to motor and parts devoted to sensory. (not impressed yet, just wait) so, it turns out that when we watch someone else throw a ball, the same part of their brain that caused them to throw the ball is activated in our brain! we are trying to learn what they did, what they felt, etc. if we see someone break their leg, the same sensory part of our brain is activated as theirs. feeling disgust from smelling a bad ordor and observing disguest in another person activates the same part of the insular cortex. this is termed the "mirror neuron system"

it has been proposed that a malfunctioning mirror neuron system is the cause of symptoms of autistic children. they may understand the intentions of others cognitively but lack the mechanism for understanding them experientially. just my speculation, but i think this might also explain why some people (usually women, and especially moms) are better at empathizing with people. maybe they have a higher developed mirror neuron system?!

test day

its test day. so, im not really learning anything new, just memorizing and reviewing. so, please take the time to go to this website and "sign a cast." it takes less than 30 seconds and someone will donate $5 to a kid who needs a surgery.
http://www.helpcurenow.org/site/c.nvI1IeNYJyE/b.4137607/k.9A91/Sign_a_Cast.htm

thanks!

alcohol poll and dysdiadochokinesis

i'm a little surprised at the poll results. some have quite a bit of alcohol experience(zero order kinetics), some have none (i have no idea or first order kinetics), and others are just plain alcoholics (mmm... alcohol). it turns out, as emily so expertly pointed out that alcohol is a mixed order or dose dependent. when a drugs elimiation is mediated predominantly by metabolism, its elimination will tend to follow first order kinetics when concentrations are well below the Km of the metabolic enzymes, but will follow zero order kinetics at high doses that greatly exceed the Km of the metabolic enzymes due to saturation of the metabolic pathways. alcohol is one such drug.

so congrats to those of you who voted, you're all a little wrong, and all sort of correct. just remember... "you don't booze, you don't win. you booze you win. you don't booze you don't race you don't win, you booze you race you win."

dysdiadochokinesis: the ability to preform rapidly alternating movements. this is impared in cerebellar damage. so whatever you do this fine weekend, don't damage your cerebellum!

smooth pursuit... not just a nickname for a girl i know...

first let me say that its almost midnight and im still at school studying, and i have to say that medical school is perhaps the coolest thing that i have ever done and i feel so privlaged to be here. let me tell you what i have learned today.

smooth pursuit: this refers to the eyes tracking an object slowly across your visual field. the ability comes for the occipital lobe. however, it is impossibe to do this unless you are following an object. try it. start at the corner of the ceiling and try to slowly move your eyes to the other corner. your eyes will jump from spot to spot. now follow your finger, its a smooth movement. clinical application: this is how you tell if a schizophrenic person is really seeing something, if they can smoothly track it with their eyes. crazy, huh?
btw, the fast movement of your eyes is controlled by the frontal lobe of the brain.

random fact: men have a 1:2 chance of getting some form of cancer anywhere in the body during their lifetime. guys, look at your roomate/cubicalmate/playmate (oh, wait...) and chances are either you or they will develop cancer. most likely cancer? prostate, 1:6 chance.

tonight i was walking across the atrium of the school and tripped, but didn't fall. at first i blushed and hoped that no one saw. then i just realized that i knew the pathway that fired to keep me upright. my semicircular canals sent a signal to the vestibulochocler nerve (Crainial Nerve VIII) to my cerebellum through the inferior cerebellar peducle to the flocculonodular lobe, then to the fastigial nucleus, then out to the vestibular nuclei then down the spinal cord thru the lateral and medial vestibulospinal tract to my arms and legs to respond to keep me from falling. and it all took place in less than a second without me even thinking about what i was doing. amazing!

thank God we have such amazing and complex systems. i really am in awe of the body im struggling to learn about.

what to look forward to tomorrow? dysdiadochokinesia. (it really is a word, i promise)

hijacking viruses

many diseases are characterized by the lack of something, perhaps an enzyme. or sometimes it is benificial to provide a growth factor. in these cases, it would be benificial to add a gene to a cells DNA. but how? well, some really smart people realized thats what viruses do, so why not hijack them and make them work for us? so they did. there are 5 kinds of viruses we use.
1)adenovirus- most commonly used; infects respiratory epithelium,
disadvantages- very immunogenic (causes immune reaction), infection only lasts a few months
2)adeno-associated virus - infects many cell types, no immune response
disadvantage- hard to harvest to any large number
3)retrovirus - used to treat immune deficiencies, generated in high titer
disadvantage- only integrates into dividing cells, and the site of intigration is unpredictable so it could insert anywhere and cause cancer!
4) lentivirus - virus associated with HIV, infects all cells, gene expression lasts for years
disadvantage - site of integration unpredictable
5) herpesvirus - (yes, as in herpes the STD), infects neurons
disadv. - large and dificult to use

once you insert a gene via a virus, it is always there, you can never get it out. so, hope you don't screw up! what they started doing is inserting a progene, meaning you have to give a drug or something to make that gene active. when you don't want the gene to be expressed anymore, then you stop taking the drug. kind of eliminates the purpose of inserting the gene in the first place (so you don't have to remember to take your drug) but it still has its advantages.

amazing drug that keeps on giving!

i still can't get over how cool this one is... so some really smart people realized that our cells secrete a molecule we decided to call "nerve growth factor" (NGF). they then thought, well, if it does what it's called, then why don't we use it to treat neuronal degenerative diseases? so they did. how did they deliver it? the took a really long needle and injected it into the lateral ventricles! that is in the very center of your brain! they had to go through the skull, through the brain and sinuses and meningies and all that menusha with a needle! unbelieveable. turns out the patients all developed debilitating neuropathies, so they stopped the trial. but not done yet. they are currently back at it, but delievering it a diferent way.
round 2: they are implanting genetically engineered fibroblasts (special type of cell) that secrete NGF into the forebrain! awesome right? thats like putting a drug into the sight of action that just keeps on giving! so far, they are having great success at improving cognitive function in diseases such as alzheimer's.

there are some pretty awesome other techinques they are using or developing, but i have to go learn about them right now. more later...

alcohol

in pharm drugs fall in to two classes of kinetics. first order or zero order. it deals with their clearance, or how fast the drug is eliminated from the body. first order kinetics is what almost all drugs are. first order drugs are cleared with a constant half-life. this means that they are concentration dependent. the more drug present, the faster it will be cleared. zero-order kinetics means that the drug clearance is constant. it does not have a constant half life. so if you have a huge amount of that drug in your system, it will be eliminated from the body at the same rate is if you had just a little. the drug metabolism pathways are saturated.

I'm going to make this post interactive. take my poll. from your experience with drinking, do you think alcohol is first order or zero order?

stroke

when someone has a stroke in the right brain, they have left sided symptoms. this is because the motor neurons cross to the other side in the lower medulla. the top of the face, such as your forehead does not experience these symptoms however, because the motor neurons that control these muscles come from both sides. cool huh?

branchial arch's

the first pharyngial arch gives rise to the muscles of mastication and they are innervated by cranial nerve V
the second pharyngial arch gives rise to the muscles of facial expression innervated by CN VII
the thrid is the pharynx/larynx innervated by CN's IX and X.

also the lateral cuneate nucleus sends out tracts known as the cuneocerebellar tract that enters the cerebellum via the inverior cerebellar peduncle, along with the DSCT (dorsal spinocerebellar tract), fibers from the contralateral inferior olive, and im pretty sure there is one more but i can't remember the name...

out like gout...

actually tophaceous gout. i saw it today in clinic. it was crazy. huge bony-looking growths on the olecranon process (elbow) and digits (fingers). it is cause by a deposit of monosodium urate crystals from an over production or under excretion of uric acid. it accumulates in the soft tissue, usually joints, especially the first metatarsophalyangeal joint (big toe). when this happens its called podegra. tophaceous gout occurse when tophi (bumps) appear on the joints, usually 12 years after they have had hyperuricemia.

acute treatment - NSAIDs or colchicine. colchicine you give at increasing doses until they have diarrhea, then you back the dose down a bit and keep them at that level. i prescribed colchicine tonight.

chronic treatment - keep the patient on NSAIDs or colchicine and treat the hyperuricemia, but not until the acute episode is over, or you can mobilize the crystals. typical drug is allopuronol.

my attending tonight told me to go home and look up this disease and the treatment because i saw it in clinic and would never forget it. i hope he is right. thanks RL, your huge tophi are engrained into my memory forever.

sad med school fact

i think i studied for 8 hours today and i cant tell you what i learned. my brain is toast.

Lou Gehrig's Disease

fact #6

ALS or amyotrophic lateral sclerosis, aka Lou Gehrig's Disease. This one is crazy. You start to notice weakness or stiffness or cramping in your arms and/or legs. You go to the doctor, they diagnose you with ALS if your lucky*. Lucky not because they can do anything, you just know that you will die a terrible death in 3-5 years. The nerves in your ventral grey horn in the spinal column die, causing you to loose all function of your voluntary muscles (save your eye muscles, oh boy!) You cant swallow, protect your airway, or talk. but your muscles do spontaneously twitch, until they completely atrophy. Then you die because you cant contract your diaphragm (from the phrenic nerve, cervical roots 3-5).

Whelp, sorry this is a pretty morbid post. I went for the longest run of my life today (16 miles) for two reasons. one because im training for a marathon. the second reason is because i can. the longer im in medical school and the more i learn about these terrible diseases, the more i just want to drop out of medical school and enjoy life. it can go so fast. if your diagnosed with pancreatic cancer, you usually have about 3 months to live and then your 6 feet under.

so, i end with this, a challenge to get outside and do anything. and thank God that you can.

fact #5

graphesthesia is a neurological test used to examen higher brain function. the doctor draws on the hand of the patient, and they should be able to recognise the nuber or letter that was drawn. if they cant, it could be the sign of a previous stroke has occured.

repetitio est mater studiorum

repetition is the mother of learning...

so i failed already in posting everyday, but i'll make up for it. let me explain where i have been. while leaving clinic tuesday night, i realized my friends window had been smashed and our backpacks were stolen, along with our notes and books. bummer deal. it actually really upset me more than i thought. I guess God is teaching me to hold my possessions more loosely. They are his after all...

cool fact #2:
there is a drug, the name escapes me (i left my binder at school) that is extracted from the saliva of a leech!

fact #3
we started behavior development today. we looked at a CT of a healthy 3 yo baby brain compared to a neglected (only socially, but still well fed) 3 yo brain. the neglected one was literally half the size! i couldn't believe it, infact i just stared at the screen with my mouth open for a while, thinking of my sister who was raised in an orphanage until age 4. i guess that explains a lot.

fact #4
i thought i diagnosed my mom today with hyperekplexia aka "startle disease" mom jumps every time her phone rings. sounds like a diagnosis, right? well, turns out its a bit more severe than that. these spasms can actually mimic seizures, leading to apnea and death. well, i was wrong with my first diagnosis (thank goodness) but i'm still searching...

hello world... im an M2

so, i really hate to write. in fact, that's probably why i was a science major in undergrad. that was my assurance that i wouldn't have to write many papers. i'll take a test any day over having to write a paper.

so why start a blog? well, i have a couple friends who blog. they convniced me to try it. and, in a futile attempt to remember the vast amount of knowledge that is expected to be memorized by medical students, i have devised a plan to help remember this stuff. I'll try to post once a day the most interesting, or obscure, or perhaps just the fact that i find hardest to memorize. maybe this way I'll be able to convert that bit of information into a neuronal synaptic pattern in my brain that will fire when prompted on a test. without any further blogging, today's fact:

100,000 people a year die from pharmacological errors. that seems like a high number to me. it might be a good idea to question your doctor, nurse, or who ever is giving you that injection/pill/iv drip next time...