Saturday, May 30, 2009

Tiny Porous Nano-Spheres Carry 2 Drugs at Once

Ames Lab researchers at Iowa State University continue their work with porous silica nano-spheres as drug delivery systems. This time, they have devised nano-systems capable of delivering two different drugs simultaneously.
A boronic acid-functionalized mesoporous silica nanoparticle-based drug delivery system (BA-MSN) for glucose-responsive controlled release of both insulin and cyclic adenosine monophosphate (cAMP) was synthesized. Fluorescein isothiocyanate-labeled, gluconic acid-modified insulin (FITC-G-Ins) proteins were immobilized on the exterior surface of BA-MSN and also served as caps to encapsulate cAMP molecules inside the mesopores of BA-MSN. The release of both G-Ins and cAMP was triggered by the introduction of saccharides. The selectivity of FITC-G-Ins release toward a series of carbohydrate triggers was determined to be fructose > glucose > other saccharides. The unique feature of this double-release system is that the decrease of FITC-G-Ins release with cycles can be balanced by the release of cAMP from mesopores of MSN, which is regulated by the gatekeeper effect of FITC-G-Ins. In vitro controlled release of cAMP was studied at two pH conditions (pH 7.4 and 8.5). Furthermore, the cytotoxicity of cAMP-loaded G-Ins-MSN with four different cell lines was investigated by cell viability and proliferation studies. The cellular uptake properties of cAMP-loaded FITC-BA-MSN with and without G-Ins capping were investigated by flow cytometry and fluorescence confocal microscopy. We envision that this glucose-responsive MSN-based double-release system could lead to a new generation of self-regulated insulin-releasing devices. _ACS
The ability to release two interacting substances from separate compartments in a nano-delivery system, provides for much longer shelf life and greater potency at the time of delivery. In this case, the payoff will be stop-gap implantable blood glucose regulation.

For long term control of diabetes, working cellular systems that can synthesise their own insulin are preferable to artificial systems. In general, the same principle is valid for all replacement organs and systems.

Replacement parts that can repair themselves, and work in concert with the rest of the body, are preferable to "one trick pony" replacements that too easily give out.

Almost certainly the best use of the Ames nano-spheres will be for genetic therapies to permanently alter gene expression of cells and tissues. But for now, proving the extent of functionality of this delivery system remains important.

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Tuesday, May 26, 2009

50 Best Anti-Ageing Blogs

The Ultrasound Technician Schools blog has put together a list of the 50 top anti-ageing blogs, for those who want to follow the broad range of online approaches to ageing and longevity.

Some of Al Fin's favourites that are on the list include Fight Aging, Ouroboros, and the Alliance for Aging Research.

Al Fin Longevity -- this blog -- finds itself on the top 50 list under the category of Longevity and Life Extension at #43.

As a side topic, I have noticed several healthcare training related blogs that provide wide ranges of lists of blogs for various topics. Some of these lists are quite useful. In fact, I would like to see a list of the top 100 list-making blogs. Wait -- what about a top 100 list of lists of top 100 list-making blogs? How about ..... Thwack!!

All righty then. My domestic android, Valerie, has just slapped me to bring me out of my list fugue. As Valerie points out, by the time you compiled the ultimate top 100 list of top 100 lists of lists of top 100 list-making blogs, the entire list would probably be obsolete. Please pardon me for the regression.

As scientific research pushes on, an extended lifespan becomes much more likely. The challenge will be not so much to keep living, but to combine the optimum mixture of enjoyable and important activities in order to fill one's life satisfactorily.

More important than improving the quantity of life is improving the quality of life. But doing both at the same time beats either one alone.


Monday, May 18, 2009

A Better Matrix for Artificial Tissues and Organs?

One of the challenges of creating artificial organs for replacement of human body parts is the need for a structural matrix to build the functional tissue around. Australian and Korean scientists have developed an interesting approach to the problem by pairing carbon nanotubes and DNA strands together, then treating them with calcium chloride solution to create cross-linking between the fibres.
The new concept uses DNA strands as a matrix; the strands completely “wrap” the scaffold-forming carbon nanotubes in the presence of an ionic liquid, networking them to form a gel. This gel can be spun: just as silk and synthetic fibers can be wet-spun for textiles, the gel can be made into very fine threads when injected into a special bath. The dried fibers have a porous, sponge-like structure and consist of a network of intertwined 50 nm-wide nanofibers. Soaking in a calcium chloride solution further cross-links the DNA, causing the fibers to become denser and more strongly connected.

These spongy fibers resemble the collagen fiber networks of the biological extracellular matrix. They can also be knotted, braided, or woven into textile-like structures. This results in materials that are as elastic as the softest natural tissues while simultaneously deriving great strength from the robust DNA links. An additional advantage is the electrical conductivity of the new material, which can thus also be used in electrodes for mechanical actuators, energy storage, and sensors. _Wiley

A similar matrix might be seeded with living cells to create tendons, cartilage, or more complex structures such as noses, ears, blood vessels, eyelids, lips, or as support reinforcement for hernia or breast surgeries etc. Reconstructive surgery and vascular surgery would create a demand for such living replacement parts immediately, should they prove safe and durable.

For more complex organs such as kidneys, livers, lungs, and hearts, more breakthroughs will be needed. For intermediate structures such as bladders, rectums, and other GI or GU segments, the jump from simple replacement parts may not be too difficult once the best ways for making the simpler parts are perfected.

Previously posted at Al Fin The Next Level


Friday, May 15, 2009

Tiny Nerve Stimulator Implants Use RFID Tech

These tiny implantable nerve stimulators are meant to stimulate peripheral nerves to treat chronic pain and other neurological disorders. But eventually, devices this small -- or smaller -- will fit near or within the brain, to deliver tiny currents of healing and eventually pleasure.
Like some cochlear implants and other medical devices, the implant is powered with radio-frequency transmission: radio waves transmitted by the external coil generate a magnetic field in the internal coil, which powers the electrodes. Adopting technologies from the rapidly advancing RFID world has allowed the researchers to further shrink the device. "Instead of trying to transfer energy from two coupled antennas to do telemetry, which is a common approach for medical devices, RFID is geared to have very small transponders, so you don't need a large coil," says Joseph Pancrazio, a program director at the National Institute for Neurological Disorders and Stroke, a government funding agency, in Bethesda, MD, that has given the company small business loans.

The research is still in a very early stage. Researchers have developed a prototype device, which they are testing in rats. The device can effectively stimulate peripheral nerves in rats, although it's not yet clear whether the electrical stimulation alleviates chronic pain. (Scientists assess chronic pain in rats by recording how much the animals eat; a rat in pain won't eat as much.)

Some scientists are skeptical that the device will be powerful enough to deliver a therapeutic level of stimulation. "The main limitation of any electronic device small enough to be injected into the body is that it must receive enough power to operate its circuitry and provide the required stimulation parameters," says Gerald Loeb, director of the Medical Device Development Facility at the University of Southern California, in Los Angeles. Loeb has also developed an injectable radio-powered microstimulator, which he says has encountered substantial limitations in range and power.

"We believe we can do it with less power," says Scott Armstrong, MicroTransponder's chief technical officer. However, he declined to give further details of the technology for proprietary reasons. _TechnologyReview
If not now, soon. It is quite clever of the researchers to use RFID technology for implantable nerve stimulators. Such an approach could be easily transferred to intracranial implants-without-antennas, as long as the power signal was able to safely penetrate the skull without damaging intervening tissues. Otherwise, antennas that are colour-matched to the person's hair could transmit the power signal to the implant. Advances in biocompatible materials will make such long-term implants viable.

Needless to say, technology that allows for miniaturisation of implants should also allow for simultaneous placement of multiple, strategically-placed implants that could communicate with each other, and coordinate for sophisticated neuro-stim routines.

Cross-posted at Al Fin


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