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April 21, 2009

BehindTheMedspeak: Fluorescent anesthetic

Via rob

Long story short: Scientists have identified a fluorescent anesthetic compound which can be localized precisely within the body, perhaps offering insight into where — and how — anesthetics work, two of the great unsolved questions in neuroscience.

An April 3,2009 PhysOrg.com article, which follows, offers more detail.


Researchers Demonstrate a New Model for Drug Discovery With a Fluorescent Anesthetic

The study is published online in the Proceedings of the National Academy of Science.

Using the fluorescing compound 1-aminoanthracene, or 1-AMA, the team developed a high-throughput assay to test for new anesthetic compounds. The assay will allow researchers to search for new anesthetic drugs and new molecular targets for anesthetics while at the same time creating high-resolution images of the compounds in action, a missing component that has hindered anesthetic research.

Researchers confirmed the compound as anesthetic after testing it successfully in tadpoles. By using transparent, albino tadpoles in the study, researchers were able to follow the fluorophore tag and image it in the brain of the immobilized, living animal. Because the compound is fluorescent, researchers are able to image the compound in vivo in order to study its physiological effects. Where and how an anesthetic compound travels in an organism when administered and to what cells and concentrations are unknown in anesthetic administration and a key to improving efficacy and to reducing side effects. Because anesthetics bind weakly to their chemical targets, which may play a role in some of the unintended side effects, searching for new targets in the central nervous system is difficult.

“We don't know much about how anesthetics work at a molecular level,” said Roderic G. Eckenhoff, M.D., vice chair for research and the Austin Lamont Professor of Anesthesiology and Critical Care at Penn’s School of Medicine. “Thus, the development of new anesthetics has become a stagnant field. This new tool will allow for the high-throughput screening of novel drugs."

Researchers from the School of Medicine and School of Arts and Sciences at Penn initiated the study in response to the health-care industry’s need for new and more powerful tools to discover and test new anesthetics and to learn more about how they work. The authors identified 1-AMA in a screen for compounds that bind to a cavity in horse spleen apoferritin, HSAF, that Eckenhoff and co-workers have shown to bind clinical anesthetics.

Researchers noticed a resemblance in the crystal structure of the apoferritin protein to that of the transmembrane region of the superfamily of ligand-gated channels that includes the GABA receptor. Anesthetics are known to positively modulate GABA signaling.

Because 1-AMA competes with other anesthetics to bind to apoferritin, researchers surmised that the protein likely binds to the same region of apoferritin as traditional anesthetics and thus shares their mechanism of action. Fluorescence of 1-AMA is enhanced when bound to apoferritin. Thus, displacement of 1-AMA by other anesthetics attenuates the fluorescence signal and allows determination of anesthetic affinity, that is, the drugs that bind tightly to the ferritin anesthetic site. In this way, 1-AMA fluorescence could be used to discover new anesthetics. This provides a unique fluorescence assay for compound screening and anesthetic discovery.

Using confocal microscopy to image the distribution of the protein, the team found that 1-AMA localizes largely in the brain and olfactory regions, unlike some general anesthetics which spread widely throughout the body. Ideally, clinical anesthetics would have a very focused target area in order to minimize systemic toxicity.

The Penn team will now collaborate with the National Chemical Genomics Center in Rockville, Md., to screen rapidly for novel anesthetic compounds, allowing for the screening of hundreds of thousands of new compounds per week.

“The 1-AMA compound opens up new avenues for identifying the relevant biomolecular targets of general anesthetics,” Ivan J. Dmochowski, PhD, assistant professor in the Department of Chemistry at Penn, said.

“1-AMA appears to be specific in its binding to proteins and also in its in vivo localization, which should give us the opportunity to determine its mechanism of action,” he said. “We hope to be able to extend our findings to learn how current general anesthetics, such as propofol, work in human patients. There are many different and challenging aspects of trying to learn how anesthetics work that involve medicinal chemistry, biochemistry, molecular modeling, imaging, cell electrophysiology, pharmacology, neurobiology and animal physiology.”

According to the study, 1-AMA increases the transmission potential of the body’s main neurotransmitter inhibitor, GABA. The compound also gives an appropriate dissociation constant, Kd 0.1 mM, for binding to the general anesthetic site in horse spleen apoferritin, meaning the compound is behaving as traditional general anesthetics would in humans.

In use for more than 150 years, general anesthetics are one of medicine’s greatest advances and yet there is still much to be learned about them. For many of the most commonly used anesthetic compounds, the molecular mechanisms behind their numbing effects and the way these compounds travel the pathways of the body remain poorly understood or altogether unknown.

According to the study team, anesthetics can bring on potentially harmful, even deadly, side effects for patients including rapid drops in blood pressure and heart rate, nausea and potentially irreversible cognitive problems, especially in older patients.


The abstract of the PNAS report, published online on April 3, 2009, follows.


Identification of a fluorescent general anesthetic, 1-aminoanthracene

We identified a fluorophore, 1-aminoanthracene (1-AMA), that is anesthetic, potentiates GABAergic transmission, and gives an appropriate dissociation constant, Kd ≈ 0.1 mM, for binding to the general anesthetic site in horse spleen apoferritin (HSAF). 1-AMA fluorescence is enhanced when bound to HSAF. Thus, displacement of 1-AMA from HSAF by other anesthetics attenuates the fluorescence signal and allows determination of Kd, as validated by isothermal titration calorimetry. This provides a unique fluorescence assay for compound screening and anesthetic discovery. Additional electrophysiology experiments in isolated cells indicate that 1-AMA potentiates chloride currents elicited by GABA, similar to many general anesthetics. Furthermore, 1-AMA reversibly immobilizes stage 45–50 Xenopus laevis tadpoles (EC50 = 16 μM) and fluorescence micrographs show 1-AMA localized to brain and olfactory regions. Thus, 1-AMA provides an unprecedented opportunity for studying general anesthetic distribution in vivo at the cellular and subcellular levels.


Legend for photo up top: "Confocal micrograph of albino stage 50 Xenopus laevis tadpole immobilized with 1-AMA for 1 hour in pond water. Image of Xenopus head shows 1-AMA localization within the brain, spinal cord, and olfactory system. Credit: Christopher Butts, University of Pennsylvania."

[via rob]

April 21, 2009 at 04:01 PM | Permalink | Comments (2) | TrackBack

Best ad of the week


It appears on the back page of the first section of today's Washington Post, courtesy of the U.S. Business and Industry Council.

April 21, 2009 at 03:01 PM | Permalink | Comments (1) | TrackBack

Biannual — twice a year or every two years?

"When we describe something as 'biannual,' we can mean either that it occurs twice a year or that it occurs once every two years. So how does someone know which particular meaning we have in mind? Well, unless we provide them with a contextual clue, they don't. Some people prefer to use 'semiannual' to refer to something that occurs twice a year, reserving 'biannual' for things that occur once every two years. This practice is hardly universal among English speakers, however, and 'biannual' remains a potentially ambiguous word. Fortunately, English also provides us with 'biennial,' a word that specifically refers to something that occurs every two years or that lasts or continues for two years."
[via Burdujan Radu and Cary Sternick]

April 21, 2009 at 02:01 PM | Permalink | Comments (1) | TrackBack

naoLoop — One pocket to hold them all

"naoLoop's extremely flexible polyester/latex band can stretch more than 50% and holds your items tightly and safely together so nothing can slip out."


"One pocket for cards, mobile, money, MP3 player, perfume, eyeshadow."


6cm x 6cm x 0.5cm.



[via noquedanblogs]

April 21, 2009 at 01:01 PM | Permalink | Comments (0) | TrackBack

FastFoodMaps.com — Anywhere, anytime, for any reason


Nice mashup.

AKA "triglycerides 'R' us."

[via Milena]

April 21, 2009 at 12:01 PM | Permalink | Comments (2) | TrackBack

What are they?


Answer here this time tomorrow.

April 21, 2009 at 11:01 AM | Permalink | Comments (4) | TrackBack

A request from Cuba (pocket sax from PVC)


Last Tuesday (April 14, 2009) I received the following email from Gabino Cid of Havana, Cuba.


A request from Cuba (pocket sax from PVC)

My name is Gabino Cid, and I live in Havana, Cuba.

I love sax music (I always loved it), and I found your web posting about the plastic pocket-sax (http://www.bookofjoe.com/2008/08/pocket-saxophon.html ) in internet, a few months ago. I’m not a musician, I just like to play music at home, and just learning to play recorder (sweet flute). For several reasons, I’ll never have a real sax, nor even a plastic pocket sax, so, I decided to make one for me, using a PVC water pipe, with the same fingering pattern of the recorder (that make me things easier to me !!!).

I used a real alto sax mouthpiece (I bought a second hand one, in 5 USD — don’t tell my wife, I told her that some friend gave it to me for free, hehehehe), a sax reed (1 USD), and PVC plastic tubes (for water piping). I made some calculation in my PC, in order to design the holes and the fingerings like a recorder (sweet flute), and it works!!! Once I finished and tuned it (it is in C4), I painted it with black metallic paint. I’m sending you a picture of the instrument I made [top].

This is me learning to play my homemade PVC pocket sax:


And this was the last training session (last week)…


But I have a real trouble: My design doesn’t allow me to go higher than one single octave (from C4 to C5). I’m attaching the drawings [below]


of my “instrument”…. I read that the pocket sax does cover two full octaves. And for me, it is impossible to make it, without help. I'll never be closer to a real pocket sax (I live in Cuba), so, I can't "copy" (sorry for the expression) the measurements.

I understand that it is not fair to “hack” the creator’s masterpiece’s design, but, believe me, I don’t want to do that for commercial or piracy purposes, just to have my own pocket sax, and I have no ways to buy me one for me. I broke my “real” reed, so, I’m making my own reeds too…. but when I had the real one, I couldn’t go higher that C5 either, so, my homemade reeds are not the problem….

Please, could you be so kind of sending me some drawings — or tips — about the plastic pocket sax design (position of the holes, diameters, etc) that help me to improve my “instrument”, and then I could enjoy it better?

Thank you very much. I’m sorry about my English. I hope you can understand this letter.

Sincerely yours

Gabino Cid



Now, I know there is someone out there somewhere who can help Mr. Cid.

A good chance for joehead nation to show its stuff.

April 21, 2009 at 10:01 AM | Permalink | Comments (1) | TrackBack



Created by Janine Jonneg from 30-to-40-year-old doll eyes.


[via DaWanda and my7475]

April 21, 2009 at 09:01 AM | Permalink | Comments (0) | TrackBack

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