tag:blogger.com,1999:blog-5429398385804955922024-03-06T09:05:18.831+13:00CmCl3Curious chlorideJoanna Wojnarhttp://www.blogger.com/profile/15686958330818535013noreply@blogger.comBlogger8125tag:blogger.com,1999:blog-542939838580495592.post-84230537204508361072013-03-21T11:47:00.002+13:002021-05-19T11:40:10.066+12:00The Great Pacific Garbage Patch<div style="text-align: justify;">
<b><span style="color: #333333;"><span style="font-family: Georgia, Times New Roman, serif;">How plastic is changing the ecosystem
of the North Pacific Gyre</span></span></b></div>
<div class="MsoNormal">
<div style="text-align: justify;">
<div class="MsoNormal" style="margin-bottom: 0.0001pt;">
<br /></div>
<div class="MsoNormal" style="margin-bottom: 0.0001pt;">
<span style="font-family: Georgia, Times New Roman, serif;"><span style="color: #333333;">You’ve probably heard of the Great Pacific Garbage Island – a floating
island of solid plastic and trash, somewhere out in the North Pacific.
Well, it doesn’t exist, at least not in the form that seems to have pervaded
popular culture.</span><span style="color: #333333;"><o:p></o:p></span></span></div>
<div class="MsoNormal" style="margin-bottom: 0.0001pt;">
<br /></div>
<div class="MsoNormal" style="margin-bottom: 0.0001pt;">
<span style="font-family: Georgia, Times New Roman, serif;"><span style="color: #333333;">In the North Pacific Ocean, the northern jet stream and the
opposite-moving southern trade winds create an oceanic gyre. In the
centre is a large area of relatively stationary water, while the steadily turning
currents surrounding it create a flow much like a whirlpool. This flow
gathers floating garbage and debris, which builds up in the centre as it cannot
escape the vortex once it enters it. This phenomenon, together with the world’s
increasing reliance on, use, and (inappropriate) disposal of plastics, has
created the so-called Great Pacific Garbage Patch.</span><span style="color: #333333;"><o:p></o:p></span></span></div>
<div class="MsoNormal" style="margin-bottom: 0.0001pt;">
<br /></div>
<div class="MsoNormal" style="margin-bottom: 0.0001pt;">
<span style="font-family: Georgia, Times New Roman, serif;"><span style="color: #333333;">It was predicted in 1988 in a scientific publication, and observed
first-hand in 1997 by oceanographer and racing boat captain Charles J.
Moore. He was returning to California from a yachting race in Hawaii,
when he</span><span style="color: #333333;"> </span><span style="color: #333333;"><a href="http://www.naturalhistorymag.com/htmlsite/master.html?http://www.naturalhistorymag.com/htmlsite/1103/1103_feature.html"><span style="color: #996e22; mso-bidi-font-size: 11.0pt;">encountered the floating trash</span></a>:</span></span></div>
<blockquote class="tr_bq">
<span style="font-family: Georgia, Times New Roman, serif;"><i><span style="color: #333333;">Yet as I
gazed from the deck at the surface of what ought to have been a pristine ocean,
I was confronted, as far as the eye could see, with the sight of plastic.
It seemed unbelievable, but I never found a clear spot. In the week it took to
cross the subtropical high, no matter what time of day I looked, plastic debris
was floating everywhere: bottles, bottle caps, wrappers, fragments. </span></i></span></blockquote>
<div class="MsoNormal">
<span style="font-family: Georgia, Times New Roman, serif;"><span style="color: #333333;">The
disturbing image these eloquent words portrayed attracted significant attention
from the media, and variants on “the Great Pacific Garbage Island” have
appeared in countless newspapers and magazines. Unfortunately at some
point – whether accidentally or on purpose to make the story more shocking – a
picture of highly polluted Manila harbour was <a href="http://io9.com/5911969/lies-youve-been-told-about-the-pacific-garbage-patch">mislabelled</a> as the Great Pacific
Garbage Island.</span><span style="color: #333333;"><br />
<!--[if !supportLineBreakNewLine]--><br />
<!--[endif]--><o:p></o:p></span></span></div>
<div align="center">
<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td><a href="http://img.gawkerassets.com/img/17nblqmbe23fyjpg/original.jpg" style="margin-left: auto; margin-right: auto;"><img border="0" height="225" src="http://img.gawkerassets.com/img/17nblqmbe23fyjpg/original.jpg" width="400" /></a></td></tr>
<tr><td class="tr-caption" style="font-size: 13px;"><div class="MsoNormal">
NOT the Great Pacific Garbage Island, but Manila Harbour.</div>
</td></tr>
</tbody></table>
<div style="text-align: start;">
<div style="text-align: justify;">
<span style="font-family: Georgia, Times New Roman, serif;">Since then, this highly evocative image has has become part of the myth of a solid island of garbage.</span><span style="font-family: Georgia, 'Times New Roman', serif;"> Despite efforts by scientists to bring a "<a href="http://oregonstate.edu/urm/ncs/archives/2011/jan/oceanic-%E2%80%9Cgarbage-patch%E2%80%9D-not-nearly-big-portrayed-media">reality check</a>" to the discussion, the myth persists, as can be seen by the recent publication of two graphic novels portraying the </span><span style="font-family: Georgia, Times New Roman, serif;">garbage patch as a floating solid island of trash.</span></div>
</div>
</div>
<div align="center">
<br /></div>
<div align="center"><table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto;"><tbody><tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEg8PUmjTsGw9kb-ER9XTTSScS9IpGq-InnJ3eVChnsmHBvx0kL8a3jMuQSYaNG-Ow9YFxcjOqguexr4oXa-ugzj0DePx37K563FC6HacFjYQ1lMYWP51rQ2j184lCMO8yEgtBHLOhBWlkHh/" style="margin-left: auto; margin-right: auto;"><img alt="" data-original-height="1858" data-original-width="1200" height="240" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEg8PUmjTsGw9kb-ER9XTTSScS9IpGq-InnJ3eVChnsmHBvx0kL8a3jMuQSYaNG-Ow9YFxcjOqguexr4oXa-ugzj0DePx37K563FC6HacFjYQ1lMYWP51rQ2j184lCMO8yEgtBHLOhBWlkHh/" width="155" /></a></td></tr><tr><td class="tr-caption" style="text-align: center;"><a href="https://www.joeharris.net/work/great-pacific">Great Pacific</a> by Joe Harris</td></tr></tbody></table><br /> <table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto;"><tbody><tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEi_HUcEV76s60NklDc-Dfx1tgRV0-xUBV21qU53phppRGPumFnK1wE-DAjFHfyqvrS6UDM3QotraVMer86lHtzGIw53knKoALp4cQrS9EwhT_ApxoYfxQsYJVJo9X_tIkjm93xM-r4raC0c/" style="margin-left: auto; margin-right: auto;"><img alt="" data-original-height="500" data-original-width="400" height="240" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEi_HUcEV76s60NklDc-Dfx1tgRV0-xUBV21qU53phppRGPumFnK1wE-DAjFHfyqvrS6UDM3QotraVMer86lHtzGIw53knKoALp4cQrS9EwhT_ApxoYfxQsYJVJo9X_tIkjm93xM-r4raC0c/" width="192" /></a></td></tr><tr><td class="tr-caption" style="text-align: center;"><a href="https://www.amazon.com/Not-Plastic-Bag-Archaia-Entertainment/dp/1936393549">I'm not a plastic bag</a> by Rachel Hope Allison</td></tr></tbody></table><br /><div style="display: inline-block;"><br />
<div class="MsoNormal" style="text-align: start;">
</div>
</div>
</div>
<div class="MsoNormal" style="margin-bottom: 0.0001pt;">
<span style="color: #333333; font-family: Georgia, 'Times New Roman', serif;">The reality is somewhat different. While some large bits of debris can be found, most of the plastic pieces are are smaller than 1 cm cubed, and many can even be microscopic. </span><br />
<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="http://farm4.staticflickr.com/3051/3856006023_981a875390.jpg" style="margin-left: auto; margin-right: auto;"><img border="0" height="213" src="http://farm4.staticflickr.com/3051/3856006023_981a875390.jpg" width="320" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;">The actual Pacific Garbage patch. Area of this photo is approximately 5′ by 10′.<br />
Photo: Scripps Institution of Oceanography, 2009 SEAPLEX cruise.</td></tr>
</tbody></table>
<span style="color: #333333; font-family: Georgia, 'Times New Roman', serif;">This is not by any means to say that the garbage patch is not a problem. Clearly, birds and fish often mistake the plastic for food, eat it, and, unable to digest it, can slowly <a href="http://www.guardian.co.uk/environment/gallery/2009/nov/03/albatross-plastic-poison-pacific">starve to death</a>. Yet there are creatures that are positively thriving in this new "<a href="http://en.wikipedia.org/wiki/Plastisphere">plastisphere</a>" environment: </span><span style="color: #333333; font-family: Georgia, Times New Roman, serif;">water skaters, small crabs, barnacles, and bryozoans. Some of these creatures are enjoying a veritable boom time - but this can lead to dramatic changes in the ecosystem of the ocean, especially when foreign creatures invade new areas previously inaccessible to them. Apart from possibly doing damage themselves (like barnacles and bryozoans do to ships hulls), these new creatures also attract their predators, which can also compete for other food sources with the locals. </span><span style="color: #333333; font-family: Georgia, 'Times New Roman', serif;">The plastisphere is "</span><a href="http://io9.com/5911969/lies-youve-been-told-about-the-pacific-garbage-patch" style="font-family: Georgia, "Times New Roman", serif;">an ecosystem out of balance</a><span style="color: #333333; font-family: Georgia, 'Times New Roman', serif;">", and may pose a real threat to the long term health of the world-wide oceans.</span><br />
<span style="color: #333333; font-family: Georgia, 'Times New Roman', serif;"><br /></span></div>
</div>
</div>
Joanna Wojnarhttp://www.blogger.com/profile/15686958330818535013noreply@blogger.com0tag:blogger.com,1999:blog-542939838580495592.post-58341882688239645172012-11-16T11:13:00.001+13:002012-11-16T11:13:11.713+13:00On the trail of bosutinib isomers<div style="text-align: justify;">
<br /></div>
<div class="MsoNormal">
<div style="text-align: justify;">
<i><span style="font-family: "Times New Roman","serif";">“Huh, that looks a bit funny.”</span></i></div>
</div>
<div class="MsoNormal">
<div style="text-align: justify;">
<br /></div>
</div>
<div class="MsoNormal">
<div style="text-align: justify;">
<span style="font-family: "Times New Roman","serif";">The
publication of a paper by Nicholas Levinson and Steven Boxer in PLoS ONE in
April 2012 hit the biochemistry world like a bombshell. Its deceptively innocuous title “<i><a href="http://www.plosone.org/article/info%3Adoi%2F10.1371%2Fjournal.pone.0029828">Structuraland spectroscopic analysis of the kinase inhibitor bosutinib and an isomer of bosutinibbinding to the Abl tyrosine kinase domain</a></i>” hid a very worrisome discovery: two
distinct chemical compounds were being sold by chemical suppliers as
“bosutinib.” In one fell swoop, dozens
of research papers and experimental results were cast into <a href="http://the-scientist.com/2012/05/13/mismarketed-chemical-causes-concern/">doubt</a>.<o:p></o:p></span></div>
</div>
<div class="MsoNormal">
<div style="text-align: justify;">
<br /></div>
</div>
<div class="MsoNormal">
<div style="text-align: justify;">
<span style="font-family: "Times New Roman","serif"; mso-bidi-font-weight: bold;">Bosutinib (developed by Pfizer) is a selective
kinase inhibitor, currently in clinical trials as a chemotherapeutic agent. Levinson, from Stanford University, was working
on a crystal structure of bosutinib bound to a tyrosine kinase called Abl. He noticed a problem with the electron
density around the area of the aniline ring – the expected chlorine at the 2
position seemed to be missing from his electron density map, and instead seemed
to present at the 3 position. Somewhat worried about this, Levinson checked the crystal structure of
botsutinib bound to serine threonine kinase 10, recently deposited in the
Protein DataBank by Stefan Knapp and coworkers from England’s Oxford
University. Upon closer inspection, their
electron density data showed that the 2-chloro atom on the aniline ring was missing,
and a chlorine atom was instead located in the meta position. The authors had noted in their title that the
compound was “radiation damaged”, but Levinson was now convinced they were
afflicted by the same problem he was seeing. <o:p></o:p></span></div>
</div>
<div class="MsoNormal">
<div style="text-align: justify;">
<br /></div>
</div>
<div class="MsoNormal">
<div style="text-align: justify;">
<i><span style="font-family: "Times New Roman","serif";">“What is bosutinib?”<o:p></o:p></span></i></div>
</div>
<div class="MsoNormal">
<div style="text-align: justify;">
<br /></div>
</div>
<div class="MsoNormal">
<div style="text-align: justify;">
<span style="font-family: "Times New Roman","serif";">Levinson
and his supervisor Boxer immediately subjected their “bosutinib” sample to a
battery of tests. Multi-dimensional NMR
experiments quickly revealed that not only was the chlorine atom at the 3
position instead of the 2 position, but the other chloro and methoxy group seemed
to be switched as well.</span><span style="font-family: "Times New Roman","serif";"> What they had been working on was not
bosutinib, but in fact a bosutinib isomer.
The difference is subtle – the isomer has the same mass and would give
the same elemental analysis results. It also
has some kinase inhibitory activity, so even biological activity assays could
be fooled. The key to distinguishing the
isomers is either X-ray, or detailed NMR analysis (preferably <sup>13</sup>C
NMR) which would reveal the symmetry present in the aniline ring in the
bosutinib isomer, but neither analysis is routinely done on reagents purchased
commercially.<o:p></o:p></span></div>
</div>
<div class="MsoNormal">
<div class="separator" style="clear: both; text-align: center;">
<a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEg13YDfGDroLrPiQ6G8KsLgdyaFyvL-wIMhF8YYnjhHoGfPudRcWEcYE8tKOYeQWNeNireuUMjOf7sX_ZMfLt-8VqT8yDGaCLzwatljHgzmIThfpKQYxw3mpxJSV6i-JG_D7opshv2I-T1B/s1600/bosutinib.jpg" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" height="320" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEg13YDfGDroLrPiQ6G8KsLgdyaFyvL-wIMhF8YYnjhHoGfPudRcWEcYE8tKOYeQWNeNireuUMjOf7sX_ZMfLt-8VqT8yDGaCLzwatljHgzmIThfpKQYxw3mpxJSV6i-JG_D7opshv2I-T1B/s320/bosutinib.jpg" width="307" /></a></div>
<div style="text-align: justify;">
<br /></div>
</div>
<div class="MsoNormal">
<div style="text-align: justify;">
<span style="font-family: "Times New Roman","serif";">Levinson
and Boxer notified the company who supplied the wrong isomer – LC Laboratories,
a subsidiary of PKC Pharmaceuticals – who immediately launched a comprehensive
investigation. What they uncovered was a
wide-spread – indeed, world-wide – problem that probably went back as far as 2006.
PKC Pharmaceuticals gathered unequivocal
physical, HPLC, TLC, and spectroscopic <a href="http://www.pkcpharma.com/TwoOrMoreBosutinibs.html">evidence</a> that at least two different
compounds have been, and possibly still are, being offered for sale under the
name bosutinib by at least 18 different biochemical suppliers. What is worse, PKC found some other spectroscopic discrepancies that may
indicate the existence of yet a third isomer.
“What is bosutinib?” is now a real and pressing question, as it impacts
on many researchers whose results from studies based on the wrong isomer may
need repeating.</span><span style="font-family: "Times New Roman","serif";"> One thing that does seem <a href="http://cen.acs.org/articles/90/web/2012/05/Bosutinib-Buyer-Beware.html">certain</a> is that the
compound being tested in clinical trials IS the real thing – Pfizer makes it
and tests it in house, and they insist that no isomeric material has ever been
administered to humans.</span></div>
</div>
<div class="MsoNormal">
<div style="text-align: justify;">
<br /></div>
</div>
<div class="MsoNormal">
<div style="text-align: justify;">
<i><span style="font-family: "Times New Roman","serif";">“How deep does the rabbit hole
go?”<o:p></o:p></span></i></div>
</div>
<div class="MsoNormal">
<div style="text-align: justify;">
<br /></div>
</div>
<div class="MsoNormal">
<div style="text-align: justify;">
<span style="font-family: "Times New Roman","serif";">The only
reasonable explanation for the production of the isomeric material seems to be
if the wrong aniline precursor was used in the synthesis.</span><span style="font-family: "Times New Roman","serif";"> This could be due to choosing an incorrect
synthesis of the anilinic isomer, purchasing the wrong isomer, or purchasing
the <i>right</i> isomer but receiving a
wrong compound.</span><span style="font-family: "Times New Roman","serif";"> The latter case is probably most worrisome,
and indeed, PKC has found that at least one incorrect compound is being sold as
the required aniline. They are currently
testing samples of “2,4-dichloro-5-aniline” obtained from 28 worldwide vendors
in order to locate a possible company that may be selling the wrong aniline to
bosutinib producers.<o:p></o:p></span></div>
</div>
<div class="MsoNormal">
<div style="text-align: justify;">
<br /></div>
</div>
<div class="MsoNormal">
<div style="text-align: justify;">
<span style="font-family: "Times New Roman","serif";">Overall,
instances of incorrect isomers being sold in the marketplace are very rare –
bosutinib may be only the <a href="http://www.sciencedirect.com/science/article/pii/0006291X9291245L">second example</a>.</span><span style="font-family: "Times New Roman","serif";"> Yet the implication that the problem goes back to an incorrect precursor is
troubling, not just because many more bosutinib analogues are being generated
by the medicinal chemistry community and may be propagating further structural
errors. Other groups may have purchased
the incorrect aniline for their own syntheses, leading to structural errors in
molecules of a completely different class.
And unfortunately there is no simple mechanism to alert the wider
scientific community of this problem. In
the end, the bosutinib saga serves as a warning to researchers never to take
the identity of purchased reagents for granted.</span><br />
<span style="font-family: "Times New Roman","serif";"><br /></span>
<div style="text-align: center;">
<span style="font-family: "Times New Roman","serif";"><i>This essay was <a href="https://docs.google.com/open?id=0B_VEMZBXLJVXV0pZemQwWERaQzg">shortlisted</a> for the Royal Society of Chemistry Science Communication Competition, 2012.</i></span></div>
</div>
</div>
<div>
<div id="ftn4">
<div class="MsoFootnoteText">
</div>
</div>
</div>
Joanna Wojnarhttp://www.blogger.com/profile/15686958330818535013noreply@blogger.com0tag:blogger.com,1999:blog-542939838580495592.post-3111797518464514422012-09-18T12:40:00.000+12:002012-09-18T12:45:29.419+12:00Slow-gradient, sample-displacement chromatography<div style="text-align: left;">
<div style="text-align: justify;">
<span style="font-family: Georgia, Times New Roman, serif;"><b>A universal, one-step method for the purification of large quantities of peptides</b></span><br />
<span style="font-family: Georgia, Times New Roman, serif;"><br /></span>
<span style="font-family: Georgia, Times New Roman, serif;">High performance liquid chromatography (HPLC) is one of the premier chromatographic techniques used world-wide for the purification of a wide variety of chemical compounds. It is essential for the isolation of new natural products, often used in the purification of synthetic molecules, ubiquitous in the peptide and protein synthesis lab, and indispensable for analytical chemistry. </span></div>
<div style="text-align: justify;">
<span style="font-family: Georgia, Times New Roman, serif;"><br /></span></div>
</div>
<table cellpadding="0" cellspacing="0" class="tr-caption-container" style="float: right; margin-left: 1em; text-align: justify;"><tbody>
<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgQKaEi2vq3K-BA8Urgvxz4S2g6Dx27l_j-u-zimIYN7IjDqkVwMicVOIq1pOpwRmq7d4Sxn8NVFmRatxOfNRC-F02bN9SIcn4NFgL9Py2l-mObTa8eJXTG3NsSGuO8tBwFVhZL-9GCYeme/s1600/Figure1.jpg" imageanchor="1" style="clear: right; margin-bottom: 1em; margin-left: auto; margin-right: auto;"><span style="font-family: Georgia, Times New Roman, serif;"><img border="0" height="400" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgQKaEi2vq3K-BA8Urgvxz4S2g6Dx27l_j-u-zimIYN7IjDqkVwMicVOIq1pOpwRmq7d4Sxn8NVFmRatxOfNRC-F02bN9SIcn4NFgL9Py2l-mObTa8eJXTG3NsSGuO8tBwFVhZL-9GCYeme/s400/Figure1.jpg" width="155" /></span></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;"><span style="font-size: 11pt; line-height: 115%;"><span style="font-family: Georgia, Times New Roman, serif;">Figure 1. Schematic </span></span><br />
<span style="font-size: 11pt; line-height: 115%;"><span style="font-family: Georgia, Times New Roman, serif;">representation of molecule</span></span><br />
<span style="font-size: 11pt; line-height: 115%;"><span style="font-family: Georgia, Times New Roman, serif;">elution profiles at different</span></span><br />
<span style="font-size: 11pt; line-height: 115%;"><span style="font-family: Georgia, Times New Roman, serif;">loading levels: a)
full peak</span></span><br />
<span style="font-size: 11pt; line-height: 115%;"><span style="font-family: Georgia, Times New Roman, serif;">resolution, b) loss of </span></span><br />
<span style="font-size: 11pt; line-height: 115%;"><span style="font-family: Georgia, Times New Roman, serif;">resolution </span></span><span style="font-family: Georgia, 'Times New Roman', serif; font-size: 11pt; line-height: 115%;">due to column</span><br />
<span style="font-family: Georgia, 'Times New Roman', serif; font-size: 11pt; line-height: 115%;">overload, </span><span style="font-family: Georgia, 'Times New Roman', serif; font-size: 11pt; line-height: 115%;">c) displacement</span><br />
<span style="font-family: Georgia, 'Times New Roman', serif; font-size: 11pt; line-height: 115%;">chromatography</span><br />
<br /></td></tr>
</tbody></table>
<div style="text-align: justify;">
<span style="font-family: Georgia, 'Times New Roman', serif;">For the most part, peak resolution is required to achieve purification by HPLC, regardless of which mode (e.g. normal phase, reversed phase) is being used. This means the compound of interest has to be clearly separated from any impurities, as depicted schematically in Figure 1a. This limits the quantities of compound that can be loaded onto the column, before resolution is lost due to sample overload and peak overlap (see Figure 1b). Purification of large quantities of compound therefore requires either multiple, repetitive runs, or the use of large (and expensive) prep columns and large quantities of solvent.</span>
<br />
<span style="font-family: Georgia, 'Times New Roman', serif; font-size: 13px;"><br /></span></div>
<div style="text-align: justify;">
<span style="font-family: Georgia, Times New Roman, serif;">Recently, researchers from the Brimble group at The University of Auckland, New Zealand, reported[1] the use of a slow-gradient, sample-displacement chromatography technique pioneered by Hodges et al.[2,3] for the successful purification of a wide variety of peptides. The key advantage of this approach is that it allows the purification of large quantities (several hundred milligrams) of peptide in a single step.</span></div>
<div style="text-align: justify;">
<span style="font-family: Georgia, Times New Roman, serif;"><br /></span></div>
<div style="text-align: justify;">
<span style="font-family: Georgia, Times New Roman, serif;">Displacement chromatography is quite an old technique. First proposed by Tiselius in 1943 and later developed further by Horváth,[4] it involves loading the sample onto a column, and then displacing it by a constant flow of a ‘displacer’ solution which contains a compound with higher affinity for the stationary phase than any of the components. As the displacer travels down the column, it pushes the other components downstream giving consecutive areas of highly concentrated pure substances (see Figure 1c). While this technique allows substantially higher sample loading, the requirement for identification of a suitable displacer and the need for its subsequent removal from the final product provide substantial drawbacks to this method.</span></div>
<div style="text-align: justify;">
<span style="font-family: Georgia, Times New Roman, serif;"><br /></span></div>
<div style="text-align: justify;">
<span style="font-family: Georgia, Times New Roman, serif;">Sample displacement chromatography removes these obstacles by using the sample components themselves as displacers. During loading of the sample mixture, which is done under overload conditions, the components compete for adsorption sites on the stationary phase. The main separation occurs during the column loading phase: the components with higher affinity will compete for sites more successfully than those with lower affinity, which will be displaced further down the column.</span><br />
<span style="font-family: Georgia, Times New Roman, serif;"><br /></span>
<span style="font-family: Georgia, Times New Roman, serif;">Rather than requiring optimization of conditions for every different peptide or molecule, a generic slow gradient of 0.1% organic modifier per minute is used to then elute the components. This approach allows excellent separation and recoveries in a single chromatographic step, and even samples of very low purity, as shown in Figure 2a, can be 'rescued' by this technique. As described by Harris et al., all 800 mgs of the crude peptide (Figure 2a) were loaded onto a semi-preparative, reversed-phased column and subjected to slow-gradient, sample-displacement purification (Figure 2b). Remarkably, 70 mgs of pure (>99%) peptide </span><span style="font-family: Georgia, 'Times New Roman', serif;">(Figure 2c) </span><span style="font-family: Georgia, 'Times New Roman', serif;">were obtained in a single chromatographic step. The detailed analysis of all the fractions, presented in Figure 2d, shows the impressive separation achieved by this method.</span></div>
<br />
<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjflgCTGNTlFa4lsIwl-eVIvQxdzJ3HYwmle5wglEMdXv8PlWC8ug7N1GiyV7KEL3cdjxlDD8SUIxu3ad1J0SEL6VNhI-G0bdF9Z1n0X3_KIpsUyPKztUrvQ6adc1LhRvvi2lZEHEij61F2/s1600/Figure2.jpg" imageanchor="1" style="margin-left: auto; margin-right: auto;"><span style="font-family: Georgia, Times New Roman, serif;"><img border="0" height="444" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjflgCTGNTlFa4lsIwl-eVIvQxdzJ3HYwmle5wglEMdXv8PlWC8ug7N1GiyV7KEL3cdjxlDD8SUIxu3ad1J0SEL6VNhI-G0bdF9Z1n0X3_KIpsUyPKztUrvQ6adc1LhRvvi2lZEHEij61F2/s400/Figure2.jpg" width="550" /></span></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;"><span style="font-family: Georgia, Times New Roman, serif;"><span style="font-size: 11.0pt; line-height: 115%; mso-ansi-language: EN-NZ; mso-bidi-font-size: 12.0pt; mso-bidi-language: AR-SA; mso-bidi-theme-font: minor-bidi; mso-fareast-font-family: Calibri; mso-fareast-language: EN-US; mso-fareast-theme-font: minor-latin;">Figure 2. a)
Analytical RP-HPLC of the crude peptide. The (*) refers to the desired product.
b) Semi-preparative RP-HPLC </span><span style="font-size: 15px; line-height: 17px;">of the crude peptide </span><span style="font-size: 11pt; line-height: 115%;">under slow-gradient, sample displacement conditions. c) Analytical RP-HPLC of the purified
peptide. d) </span><span style="font-size: 11pt; line-height: 115%;">Comparison of all material eluted from the semi-preparative
purification.</span><span style="font-size: 11pt; line-height: 115%;"> </span></span></td></tr>
</tbody></table>
<br />
<div style="text-align: justify;">
<span style="font-family: Georgia, Times New Roman, serif;">A wide range of synthetic peptides, including those with non-natural modifications such as biotin and carboxyfluorescein, have been successfully purified in the Brimble lab using this one-step, universal method. Harris et al. hope that "<i>given the data presented here, </i></span><span style="font-family: Georgia, 'Times New Roman', serif;"><i>this efficient mode of HPLC purification will be embraced by </i></span><span style="font-family: Georgia, 'Times New Roman', serif;"><i>the wider peptide community</i>."</span></div>
<div style="text-align: justify;">
<span style="font-family: Georgia, 'Times New Roman', serif;"><br /></span></div>
<div style="text-align: justify;">
<span style="font-family: Georgia, 'Times New Roman', serif;"><br /></span></div>
<div style="text-align: justify;">
<span style="font-family: Georgia, 'Times New Roman', serif;">[1] </span><span style="font-family: Georgia, Times New Roman, serif;">Harris, P. W. R.; Lee, D. J.; Brimble, M. A., <a href="http://onlinelibrary.wiley.com/doi/10.1002/psc.2432/abstract">A slow gradient approach for the purification of synthetic polypeptides by reversed phase high performance liquid chromatography</a>. </span><i style="font-family: Georgia, 'Times New Roman', serif;">J. Pept. Sci</i><span style="font-family: Georgia, 'Times New Roman', serif;">. </span><b style="font-family: Georgia, 'Times New Roman', serif;">2012, </b><i style="font-family: Georgia, 'Times New Roman', serif;">18(9)</i><span style="font-family: Georgia, 'Times New Roman', serif;">, 545-555</span><b style="font-family: Georgia, 'Times New Roman', serif;">.</b></div>
<div style="text-align: justify;">
<div class="MsoNormal">
<span style="font-family: Georgia, Times New Roman, serif;">[2] Hodges, R. S.; Burke, T. W. L.; Mant, C. T., <a href="http://www.sciencedirect.com/science/article/pii/S0021967301940361">Preparative purification of peptides by reversed-phase chromatography: Sample displacement mode versus gradient elution mode</a>. </span><i style="font-family: Georgia, 'Times New Roman', serif;">J. Chromatogr. </i><b style="font-family: Georgia, 'Times New Roman', serif;">1988,</b><span style="font-family: Georgia, 'Times New Roman', serif;"> </span><i style="font-family: Georgia, 'Times New Roman', serif;">444</i><span style="font-family: Georgia, 'Times New Roman', serif;">, 349-362.</span></div>
<span style="line-height: 115%;"><span style="font-family: Georgia, Times New Roman, serif;">[3] Chen,
Y. X.; Mant, C. T.; Hodges, R. S., </span></span><span style="font-family: Georgia, Times New Roman, serif;"><span style="line-height: 18px;"><a href="http://www.sciencedirect.com/science/article/pii/S0021967306021960">Preparative reversed-phase high-performance liquid chromatography collection efficiency for an antimicrobial peptide on columns of varying diameters (1 mm to 9.4 mm I.D.).</a> </span></span><i style="font-family: Georgia, 'Times New Roman', serif; line-height: 115%;">J.
Chromatogr., A </i><b style="font-family: Georgia, 'Times New Roman', serif; line-height: 115%;">2007,</b><span style="font-family: Georgia, 'Times New Roman', serif; line-height: 115%;"> </span><i style="font-family: Georgia, 'Times New Roman', serif; line-height: 115%;">1140</i><span style="font-family: Georgia, 'Times New Roman', serif; line-height: 115%;"> (1-2), 112-120.</span></div>
<div style="text-align: justify;">
<span style="font-family: Georgia, 'Times New Roman', serif;">[4] </span><span style="font-family: Georgia, Times New Roman, serif;">Horváth, C.; Nahum, A.; Frenz, J. H., <a href="http://www.sciencedirect.com/science/article/pii/S002196730082066X">High-performance displacement chromatography</a>. </span><i style="font-family: Georgia, 'Times New Roman', serif;">J. Chromatogr., A</i><span style="font-family: Georgia, 'Times New Roman', serif;"> </span><b style="font-family: Georgia, 'Times New Roman', serif;">1981</b><span style="font-family: Georgia, 'Times New Roman', serif;">, 218, 365-393. </span></div>
Joanna Wojnarhttp://www.blogger.com/profile/15686958330818535013noreply@blogger.com0tag:blogger.com,1999:blog-542939838580495592.post-46609114327427868662012-09-12T09:35:00.000+12:002012-09-12T09:36:54.944+12:00100% Chemical Free<i><span style="font-family: Georgia, Times New Roman, serif;">This is my winning entry for the <a href="http://www.royalsociety.org.nz/programmes/competitions/manhire-prize/2011-information/">2011 Royal Society of New Zealand Manhire Prize for Creative Science Writing</a>.</span></i><br />
<i><span style="font-family: Georgia, Times New Roman, serif;"><br /></span></i>
<div style="text-align: justify;">
<span style="font-family: Georgia, Times New Roman, serif;">“How to create a safe and chemical-free home” <a href="http://www.qldc.govt.nz/images/Files/Rubbish_and_Recycling_Resources/Chemical_Free_Cleaning_Fact_Sheet.pdf">advises</a> the Queenstown Lakes district </span><span style="font-family: Georgia, 'Times New Roman', serif;">council. Natural Pools NZ </span><span style="font-family: Georgia, 'Times New Roman', serif;">in turn, </span><ahref http:="http:" id="7036" landscapedetails_mini.asp="landscapedetails_mini.asp" style="font-family: Georgia, 'Times New Roman', serif;" web.archive.org="web.archive.org" web="web" www.landscapedesign.co.nz="www.landscapedesign.co.nz"><a href="http://web.archive.org/web/20100522095115/http://www.landscapedesign.co.nz/landscapedetails_mini.asp?id=7036">offers</a></ahref><span style="font-family: Georgia, 'Times New Roman', serif;"> “chemical-free swimming”, </span><span style="font-family: Georgia, 'Times New Roman', serif;">and a “chemical-free </span><span style="font-family: Georgia, 'Times New Roman', serif;">cosmetic” is </span><a href="http://tvnz.co.nz/health-news/chemical-free-cosmetic-created-in-nz-3359221" style="font-family: Georgia, 'Times New Roman', serif;">touted</a><span style="font-family: Georgia, 'Times New Roman', serif;"> on our evening news. </span><span style="font-family: Georgia, 'Times New Roman', serif;">These are some of the many examples of what </span><span style="font-family: Georgia, 'Times New Roman', serif;">Chemical and Engineering News has dubbed as the age of “</span><a href="http://en.wikipedia.org/wiki/Chemophobia" style="font-family: Georgia, 'Times New Roman', serif;">chemophobia</a><span style="font-family: Georgia, 'Times New Roman', serif;">”, </span><span style="font-family: Georgia, 'Times New Roman', serif;">or the irrational </span><span style="font-family: Georgia, 'Times New Roman', serif;">and unsubstantiated fear of chemistry and chemicals.</span><br />
<span style="font-family: Georgia, 'Times New Roman', serif;"><br /></span></div>
<div style="text-align: center;">
<i style="font-family: Georgia, 'Times New Roman', serif;">read the rest at <a href="http://www.listener.co.nz/commentary/100-chemical-free-by-joanna-wojnar/">The Listener</a></i>
</div>
Joanna Wojnarhttp://www.blogger.com/profile/15686958330818535013noreply@blogger.com0tag:blogger.com,1999:blog-542939838580495592.post-26640623655029417742012-09-11T07:28:00.001+12:002021-05-19T11:32:07.854+12:00The Chemical History of Anaesthesia<b style="text-align: justify;"><span style="font-family: Georgia, Times New Roman, serif;">Introduction: The Age of Agony</span></b><br />
<div style="text-align: justify;">
<span style="font-family: Georgia, Times New Roman, serif;"><br /></span></div>
<div style="text-align: justify;">
<span style="font-family: Georgia, Times New Roman, serif;">The accounts and recollections of surgery before the discovery of anaesthesia are gruesome and it is difficult to imagine what such surgery was truly like. One of the best descriptions of a pre-anaesthesia medical procedure was provided by Fanny Burney, an English author, in a letter to her sister describing her mastectomy: <i>When the dreadful steel was plunged into the breast - cutting through veins - arteries - flesh - nerves - I needed no injunctions not to restrain my cries. I began a scream that lasted unintermittingly during the whole time of the incision - and I almost marvel that it rings not in my ears still! so excruciating </i></span><i style="font-family: Georgia, "Times New Roman", serif;">was the agony.</i><span style="font-family: Georgia, 'Times New Roman', serif;">[</span><span style="font-family: Georgia, 'Times New Roman', serif;">1]</span></div>
<div style="text-align: justify;">
<span style="font-family: Georgia, Times New Roman, serif;"><br /></span></div>
<div style="text-align: justify;">
<span style="font-family: Georgia, Times New Roman, serif;">While there were some techniques used to provide a type of primitive anaesthesia that included the barbaric methods of nerve compression, deadly intoxication, exsanguination, refrigeration, carotid compression, and even concussion, ultimately a good surgeon was a <i>fast </i>surgeon.[2]</span></div>
<div style="text-align: center;">
<i><span style="font-family: Georgia, Times New Roman, serif;">read the rest at <a href="https://nzic.org.nz/app/uploads/2018/06/CiNZ-Apr-2007-min.pdf#page=19">Chemistry in New Zealand</a>.</span></i></div>
<div style="text-align: center;">
<br /></div>
<div style="text-align: center;">
<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="http://upload.wikimedia.org/wikipedia/commons/thumb/6/66/Ether_Monument_Overview.JPG/450px-Ether_Monument_Overview.JPG" style="margin-left: auto; margin-right: auto;"><img border="0" height="320" src="http://upload.wikimedia.org/wikipedia/commons/thumb/6/66/Ether_Monument_Overview.JPG/450px-Ether_Monument_Overview.JPG" width="240" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;">The Ether Monument, the oldest statue in the<br />
historic Boston Public Garden, possibly the<br />
only statue to a chemical in the world. It was<br />
erected <i>as an expression </i><i>of gratitude for the</i><br />
<i>relief of human suffering occasioned </i><i>by the</i><br />
<i>discovery of the anaesthetic properties of</i><br />
<i>sulphuric </i><i>ether</i>. It displays the description:<br />
<i>There shall be no more pain</i>.</td></tr>
</tbody></table>
</div>
Joanna Wojnarhttp://www.blogger.com/profile/15686958330818535013noreply@blogger.com0tag:blogger.com,1999:blog-542939838580495592.post-13710814849129257832012-09-10T09:02:00.000+12:002012-09-18T12:50:06.588+12:00A new rainbow of colour for bioluminescence imaging<table cellpadding="0" cellspacing="0" class="tr-caption-container" style="float: right; margin-left: 1em; text-align: right;"><tbody>
<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjRlelDCBfhFoQvGEzzZaFmszZPScMtwqdpGhdU24N_gSVEtMjip61yFBWk2aZE6n3gBrlAn83j_oKknRnAW182V4kvvY25ckXApkXVd_x-3rRaBhGjQD6-LTFa2ips9YsOu1le3CKZb1uF/s1600/luciferins2.jpg" imageanchor="1" style="clear: right; margin-bottom: 1em; margin-left: auto; margin-right: auto;"><span style="font-family: Georgia, Times New Roman, serif;"><img border="0" height="320" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjRlelDCBfhFoQvGEzzZaFmszZPScMtwqdpGhdU24N_gSVEtMjip61yFBWk2aZE6n3gBrlAn83j_oKknRnAW182V4kvvY25ckXApkXVd_x-3rRaBhGjQD6-LTFa2ips9YsOu1le3CKZb1uF/s320/luciferins2.jpg" width="168" /></span></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;"><div class="MsoNormal">
<span style="font-family: Georgia, Times New Roman, serif; font-size: small;"><span style="font-variant: small-caps;">d</span>-luciferin and
several luciferin </span></div>
<div class="MsoNormal">
<span style="font-family: Georgia, Times New Roman, serif; font-size: small;">analogues synthesized that show </span></div>
<div class="MsoNormal">
<span style="font-family: Georgia, Times New Roman, serif; font-size: small;">varying colours of emitted
light.</span></div>
</td></tr>
</tbody></table>
<div style="text-align: justify;">
<span style="font-family: Georgia, 'Times New Roman', serif;">Luciferins are a class of molecules that are oxidized by the </span><a href="http://en.wikipedia.org/wiki/Luciferase" style="font-family: Georgia, 'Times New Roman', serif;">luciferase</a><span style="font-family: Georgia, 'Times New Roman', serif;"> enzymes (for example firefly luciferase), producing oxyluciferin and energy which is released in the form of a photon of light (termed </span><a href="http://en.wikipedia.org/wiki/Bioluminescence" style="font-family: Georgia, 'Times New Roman', serif;">bioluminescence</a><span style="font-family: Georgia, 'Times New Roman', serif;">).[1] </span><span style="font-family: Georgia, 'Times New Roman', serif;">Bioluminescence is a very sensitive imaging technique, making it one of the most popular methods for visualizing biological processes</span><i style="font-family: Georgia, 'Times New Roman', serif;"> in vivo</i><span style="font-family: Georgia, 'Times New Roman', serif;">, especially in cancer biology research.[1] Bioluminescencent imaging is preferred over the fluorescent counterpart because no external light source is required,[2] and the lack of endogenous bioluminescent reactions in mammalian tissue allows for near background-free imaging conditions.[3] Unfortunately, luciferin-based bioluminescence imaging has been limited to monitoring one cell type or feature at a time, as nearly all the enzymes act on the same substrate (</span><span style="font-family: Georgia, 'Times New Roman', serif; font-size: x-small;">D</span><span style="font-family: Georgia, 'Times New Roman', serif;">-luciferin). Additionally, light of wavelengths below 600 nm is absorbed and scattered by cells, which restricts the application of this technique to only superficial tissue depths.[1]</span></div>
<div style="text-align: justify;">
<span style="font-family: Georgia, 'Times New Roman', serif;"><br /></span></div>
<div style="text-align: justify;">
<span style="font-family: Georgia, 'Times New Roman', serif;">A range of luciferin analogues have been synthesized which show excellent bioluminescence properties and great potential in cell and tissue imaging. This series of luciferin analogues which absorb at different wavelengths has raised the possibility of multicomponent imaging using multiple colours. Additionally, several of the analogues display red-shifted emission (>600nm) which give their signal better tissue penetration properties.</span></div>
<div class="MsoNormal">
<br />
<div style="text-align: justify;">
<span style="font-family: Georgia, 'Times New Roman', serif;">Researchers led by </span><a href="http://profiles.umassmed.edu/profiles/ProfileDetails.aspx?From=SE&Person=890" style="font-family: Georgia, 'Times New Roman', serif;">Stephen Miller</a><span style="font-family: Georgia, 'Times New Roman', serif;"> from the University of Massachussets Medical School synthesized four alkylaminoluciferin substrates, which showed red-shifted and more intense light emissions than </span><span style="font-family: Georgia, 'Times New Roman', serif; font-size: x-small;">D</span><span style="font-family: Georgia, 'Times New Roman', serif;">-luciferin.[4] They have also engineered several luciferase mutants that yield improved sustained light emission with aminoluciferins in both lysed and live mammalian cells.[5]</span><br />
<span style="font-family: Georgia, 'Times New Roman', serif;"><br /></span>
<span style="font-family: Georgia, 'Times New Roman', serif;">More recently, the Stanford University lab of </span><a href="http://med.stanford.edu/profiles/mips/researcher/W_Moerner" style="font-family: Georgia, 'Times New Roman', serif;">William Moerner</a><span style="font-family: Georgia, 'Times New Roman', serif;"> developed an analogue with a selenium atom in place of the native sulfur atom at position 1. The resulting selenoluciferin emits 55% of its light above 600 nm.[6]</span></div>
<br />
<div style="text-align: justify;">
<span style="font-family: Georgia, 'Times New Roman', serif;">Soon after, </span><a href="http://www.faculty.uci.edu/profile.cfm?faculty_id=5701" style="font-family: Georgia, 'Times New Roman', serif;">Jennifer Prescher</a><span style="font-family: Georgia, 'Times New Roman', serif;"> and co-workers at the University of California developed two further types of luciferin analogues, replacing the sulfur in either of the two heteroaromatic rings with nitrogen.[7] One compound specifically shows the highest blue-shift of any luciferins.</span></div>
<br />
<div style="text-align: justify;">
<span style="font-family: Georgia, 'Times New Roman', serif;">Depending on the substitution pattern, the luciferin-emitted light can span a broad range, from deep in the red (>600 nm) up to bright blue (around 460 nm). This is dependent on the identity and nature of the atoms that are substituted – for example, the more strongly electron-donating nature of the alkylamino group was hypothesized to red-shift the spectral properties. The polar effect of the selenium atom was also predicted to red-shift the emission maximum; both assumptions turned out to be correct. </span><br />
<span style="font-family: Georgia, 'Times New Roman', serif;"><br /></span>
<span style="font-family: Georgia, 'Times New Roman', serif;">While a palette of luciferin colours has now been developed, many of the analogues are still not ideal substrates. The alkylaminoluciferins show a significant reduction in light output compared to </span><span style="font-family: Georgia, 'Times New Roman', serif; font-size: x-small;">D</span><span style="font-family: Georgia, 'Times New Roman', serif;">-luciferin, consistent with product inhibition and hence lower rate of enzymatic turnover.[4] The selenocysteine analogue also has reduced light output, partly as a result of lower quantum yield.[6] Some analogues synthesized displayed very limited or even no bioluminescence, making them of little use for imaging studies.[7] Further tweaking of their structure will be required before luciferin-based multicomponent imaging is possible.</span></div>
</div>
<div class="MsoNormal">
<span style="font-family: Georgia, Times New Roman, serif;"><br /></span>
<b><span style="font-family: Georgia, Times New Roman, serif;">Background</span></b></div>
<div class="MsoNormal">
<span style="font-family: Georgia, Times New Roman, serif;"><a href="http://www.amazon.com/Luciferases-Fluorescent-Proteins-Principles-Biotechnology/dp/8178952920/">Luciferases
and Fluorescent Proteins: Principles and Advances in Biotechnology and
Bioimaging 2007</a>, V. R. Viviani, Y. Ohmiya (eds). Transworld Research
Network, 2007.</span><br />
<span style="font-family: Georgia, Times New Roman, serif;"><br /></span></div>
<div class="MsoNormal">
<b style="line-height: 115%;"><span style="font-family: Georgia, Times New Roman, serif;">References</span></b></div>
<div>
<div id="edn1">
<div class="MsoEndnoteText">
<span style="font-family: Georgia, Times New Roman, serif;"><span class="MsoEndnoteReference"><!--[if !supportFootnotes]--><span class="MsoEndnoteReference"><span style="line-height: 115%;">[1]</span></span><!--[endif]--></span> Y.-Q.
Sun, J. Liu, P. Wang, J. Zhang, W. Guo. <a href="http://onlinelibrary.wiley.com/doi/10.1002/anie.201203565/abstract"><span style="font-variant: small-caps;">d</span>-Luciferin analogues: a multicolour
toolbox for bioluminescence imaging</a>. <i>
Angew. Chem. Int. Ed</i>. <b>2012</b>, 51(34), 8428-8430</span></div>
</div>
<div id="edn2">
<div class="MsoEndnoteText">
<span style="font-family: Georgia, Times New Roman, serif;"><span class="MsoEndnoteReference"><!--[if !supportFootnotes]--><span class="MsoEndnoteReference"><span style="line-height: 115%;">[2]</span></span><!--[endif]--></span> M.
Baker. <a href="http://www.nature.com/nmeth/journal/v9/n3/full/nmeth.1919.html">A
broader palette for luciferase</a>. <i>Nat.
Methods</i>. <b>2012</b>, 9(3), 225.</span></div>
</div>
<div id="edn3">
<div class="MsoEndnoteText">
<span style="font-family: Georgia, Times New Roman, serif;"><span class="MsoEndnoteReference"><!--[if !supportFootnotes]--><span class="MsoEndnoteReference"><span style="line-height: 115%;">[3]</span></span><!--[endif]--></span> D.
M. Close, T. Xu, G. S. Sayler, S. Ripp. <a href="http://www.mdpi.com/1424-8220/11/1/180"><i>In vivo</i> bioluminescent imaging (BLI): noninvasive visualization and
interrogation of biological processes in living animals</a>. <i>Sensors</i> <b>2011</b>, 11(1), 180-206.</span></div>
</div>
<div id="edn4">
<div class="MsoNormal" style="margin-bottom: 0.0001pt;">
<span style="font-family: Georgia, Times New Roman, serif;"><span class="MsoEndnoteReference"><!--[if !supportFootnotes]--><span class="MsoEndnoteReference"><span style="line-height: 115%;">[4]</span></span><!--[endif]--></span>
G. R. Reddy, W. C.
Thompson, S. C. Miller. <a href="http://pubs.acs.org/doi/abs/10.1021/ja104525m">Robust light emission from cyclic
alkylaminoluciferin substrates for firefly luciferase</a>. <i>J. Am. Chem. Soc</i>.<b> 2010</b>, 132(39), 13586-13587.</span></div>
</div>
<div id="edn5">
<div class="MsoEndnoteText">
<span style="font-family: Georgia, Times New Roman, serif;"><span class="MsoEndnoteReference"><!--[if !supportFootnotes]--><span class="MsoEndnoteReference"><span style="line-height: 115%;">[5]</span></span><!--[endif]--></span> K.
R. Harwood, D. M. Mofford, G. R. Reddy, S. C. Miller. <a href="http://www.sciencedirect.com/science/article/pii/S1074552111003619">Identification
of mutant firefly luciferases that efficiently utilize aminoluciferins</a>. <i>Chem. Biol</i>. <b>2011</b>, 18(12), 1649-1657.</span></div>
</div>
<div id="edn6">
<div class="MsoNormal" style="margin-bottom: 0.0001pt;">
<span style="font-family: Georgia, Times New Roman, serif;"><span class="MsoEndnoteReference"><!--[if !supportFootnotes]--><span class="MsoEndnoteReference"><span style="line-height: 115%;">[6]</span></span><!--[endif]--></span>
N. R. Conley, A.
Dragulescu-Andrasi, J. Rao, W. E. Moerner.
<a href="http://onlinelibrary.wiley.com/doi/10.1002/anie.201105653/abstract">A selenium analogue of firefly
<span style="font-variant: small-caps;">d</span>-luciferin with red-shifted
bioluminescence emission</a>. <i>Angew. Chem. Int. Ed</i>. <b>2012</b>,
51(14), 3350-3353. </span></div>
</div>
<div id="edn7">
<div class="MsoNormal" style="margin-bottom: 0.0001pt;">
<span style="font-family: Georgia, Times New Roman, serif;"><span class="MsoEndnoteReference"><!--[if !supportFootnotes]--><span class="MsoEndnoteReference"><span style="line-height: 115%;">[7]</span></span><!--[endif]--></span>
D. C. McCutcheon, M.
A. Paley, R. C. Steinhardt, J. A. Prescher.
<a href="http://pubs.acs.org/doi/abs/10.1021/ja301493d">Expedient synthesis of
electronically modified luciferins for bioluminescence imaging</a>. <i>J. Am. Chem. Soc</i>. <b>2012</b>, 134(18), 7604-7607.</span></div>
</div>
</div>
Joanna Wojnarhttp://www.blogger.com/profile/15686958330818535013noreply@blogger.com2tag:blogger.com,1999:blog-542939838580495592.post-82380099828946517252012-09-04T11:35:00.000+12:002012-09-18T12:46:48.508+12:00Tasty peptides<div style="text-align: justify;">
<span style="font-family: Georgia, Times New Roman, serif;">Taste is simple, right? Table salt is salty. Sugar is sweet. Coffee is bitter. And lemons are sour.</span></div>
<div style="text-align: justify;">
<span style="font-family: Georgia, 'Times New Roman', serif;"><br /></span></div>
<div style="text-align: justify;">
<span style="font-family: Georgia, 'Times New Roman', serif;">And of course we mustn't forget </span><a href="http://www.umamiinfo.com/" style="font-family: Georgia, 'Times New Roman', serif;">umami</a><span style="font-family: Georgia, 'Times New Roman', serif;">, the fifth and youngest (most recently agreed on) taste. Described in 1908 by the Japanese scientist </span><a href="http://en.wikipedia.org/wiki/Kikunae_Ikeda" style="font-family: Georgia, 'Times New Roman', serif;">Kikunae Ikeda</a><span style="font-family: Georgia, 'Times New Roman', serif;">, it was only accepted quite recently, so that most languages do not even have their own name for it but have adopted the Japanese term.</span></div>
<div style="text-align: justify;">
<span style="font-family: Georgia, 'Times New Roman', serif;"><br /></span></div>
<div style="text-align: justify;">
<span style="font-family: Georgia, 'Times New Roman', serif;">Yet there is more to taste than simple salts (like NaCl), carbohydrates (like sucrose), alkaloids (like caffeine), and organic acids (like citric acid) or acid salts (monosodium glutamate). Peptides, despite being subjected to intensive scrutiny of the many biological functions they perform, are rarely considered in light of their taste. However, peptides essentially cover the whole range of the established tastes, and contribute significantly to the complex flavour of much of the food we eat every day.</span></div>
<div style="text-align: justify;">
<span style="font-family: Georgia, 'Times New Roman', serif;"><br /></span></div>
<div style="text-align: justify;">
<span style="font-family: Georgia, 'Times New Roman', serif;">In general, and not surprisingly, peptides with acidic residues such as aspartic or glutamic acid tend to have a sour taste. </span><a href="http://en.wikipedia.org/wiki/Taste#Sourness" style="font-family: Georgia, 'Times New Roman', serif;">Sourness</a><span style="font-family: Georgia, 'Times New Roman', serif;"> is the taste that detects acidity, through the detection of protons (hydrogen ions) that are released when the carboxylic groups of the peptide dissociate.</span></div>
<div style="text-align: justify;">
<span style="font-family: Georgia, 'Times New Roman', serif;"><br /></span></div>
<div style="text-align: justify;">
<span style="font-family: Georgia, 'Times New Roman', serif;">Salty peptides are few and far between and are often accompanied by a bitter aftertaste. The 1980s saw a flurry of research around the newly discovered </span><span style="font-family: Georgia, 'Times New Roman', serif; font-size: x-small;">L</span><span style="font-family: Georgia, 'Times New Roman', serif;">-ornithine-taurine dipeptide, which was </span><a href="http://pubs.acs.org/doi/abs/10.1021/jf00125a009" style="font-family: Georgia, 'Times New Roman', serif;">reported</a><span style="font-family: Georgia, 'Times New Roman', serif;"> to have a salty taste without the presence of any sodium. Some controversy </span><a href="http://pubs.acs.org/doi/abs/10.1021/jf00100a024" style="font-family: Georgia, 'Times New Roman', serif;">erupted</a><span style="font-family: Georgia, 'Times New Roman', serif;"> over whether the taste was actually due to the peptide, or residual contaminant NaCl, and no salty peptide so far is being used as a salt substitute.</span></div>
<div style="text-align: justify;">
<span style="font-family: Georgia, Times New Roman, serif;"><br /></span></div>
<div style="text-align: justify;">
<span style="font-family: Georgia, Times New Roman, serif;">The hydrophobic amino acids phenylalanine, tryptophan, leucine, and tyrosine have bitter tastes, and similarly peptides rich in hydrophobic residues (</span><span style="font-family: Georgia, 'Times New Roman', serif;">especially if they are at the C-terminus) </span><span style="font-family: Georgia, Times New Roman, serif;">are <a href="http://www.ncbi.nlm.nih.gov/pubmed/19153652">bitter</a> also. One of the most <a href="http://onlinelibrary.wiley.com/doi/10.1002/psc.1428/abstract">bitter peptides</a> described is the octapeptide Arg-Arg-Pro-Pro-Pro-Phe-Phe-Phe, with a bitterness comparable to that of strychnine (one of the most bitter molecules known). While humans have an innate aversion to bitter tasting molecules (as protection from ingestion of poisonous substances, such as strychnine), the rejection of bitter foods is not absolute. Foods such as beer, tea, and coffee can be highly bitter, yet are beloved world-wide. In addition, b</span><span style="font-family: Georgia, 'Times New Roman', serif;">itter peptides are found in a variety of aged or fermented foodstuffs, including cheese and meaty products such as ham, and other foods containing fermented proteins.</span></div>
<div style="text-align: justify;">
<span style="font-family: Georgia, 'Times New Roman', serif;"><br /></span></div>
<div style="text-align: justify;">
<span style="font-family: Georgia, 'Times New Roman', serif;">The archetypal umami tastant is of course glutamate, but many peptides have been claimed to be "umami peptides". The so-called "</span><a href="http://en.wikipedia.org/wiki/Beefy_meaty_peptide" style="font-family: Georgia, 'Times New Roman', serif;">delicious peptide</a><span style="font-family: Georgia, 'Times New Roman', serif;">" - the octapeptide Lys-Gly-Asp-Glu-Glu-Ser-Leu-Ala - was suggested to have an umami potency higher than glutamate itself. Unfortunately, upon re-examination of this peptide and its fragments, no real umami taste could be detected, casting the existence of umami peptides into </span><a href="http://www.springerlink.com/content/982bp0plv2tbh0rp/" style="font-family: Georgia, 'Times New Roman', serif;">doubt</a><span style="font-family: Georgia, 'Times New Roman', serif;">. Yet they have not disappeared: recent research describes umami peptides from </span><a href="http://www.ncbi.nlm.nih.gov/pubmed/22868117" style="font-family: Georgia, 'Times New Roman', serif;">peanut hydrolysate</a><span style="font-family: Georgia, 'Times New Roman', serif;"> and </span><a href="http://www.sciencedirect.com/science/article/pii/S0308814611002354" style="font-family: Georgia, 'Times New Roman', serif;">soybean paste</a><span style="font-family: Georgia, 'Times New Roman', serif;">. If these results are confirmed, these umami peptides could be very desirable flavour-enhancing alternatives to the sometimes reviled monosodium glutamate.</span></div>
<div style="text-align: justify;">
<span style="font-family: Georgia, Times New Roman, serif;"><br /></span></div>
<div style="text-align: justify;">
<span style="font-family: Georgia, Times New Roman, serif;">But it is probably a <a href="http://onlinelibrary.wiley.com/doi/10.1002/psc.1428/abstract">sweet peptide</a> that we are most familiar with - the dipeptide aspartame (<span style="font-size: x-small;">L</span>-aspartyl-<span style="font-size: x-small;">L</span>-phenylalanine methyl ester) is the most used non-caloric sweetener in the world. Discovered accidentally when a researcher licked his (contaminated) finger to lift a piece of paper, aspartame was found to be 200 times sweeter than sucrose (table sugar). Following on from this serendipitous discovery, scientists explored many alternatives more rigorously. They found that Asp cannot be substituted by any other residue, whereas Phe can be replaced by some (but not all) hydrophobic amino acids. Interestingly, they also found that all the other possible chiral isomers (<span style="font-size: x-small;">D-L, L-D</span>, and <span style="font-size: x-small;">D-D</span>) are not sweet at all, but quite bitter. Other modifications, on the other hand, have led to the discovery of super-aspartame molecules, such as <a href="http://en.wikipedia.org/wiki/Neotame">neotame</a>. It has a 3,3-dimethylbutyl group attached to the amino group of the aspartic acid, and </span><span style="font-family: Georgia, 'Times New Roman', serif;">is around 10,000 times as sweet as sucrose. Most jurisdictions have now approved its use in food.</span></div>
<div style="text-align: justify;">
<span style="font-family: Georgia, 'Times New Roman', serif;"><br /></span></div>
<div style="text-align: justify;">
<span style="font-family: Georgia, 'Times New Roman', serif;">Proteins and peptides make up a large part of the foods we eat every day, and it is clear that they play a significant role in the complex chemical interplay that is taste. Mostly, the peptides seem to contribute sweet, bitter, and sour tastes, but some evidence suggests salty and umami peptides exist also. While the taste of the sour and salty peptides is probably simply due to the presence of the charged terminals and side chains, bitter and sweet receptors are clearly activated by specific electronic and conformational features of a specific peptide (as demonstrated by the various isomers of aspartame). Peptides are therefore extremely useful tools for researching taste receptor function and leading to a better understanding of taste and taste perception.</span></div>
Joanna Wojnarhttp://www.blogger.com/profile/15686958330818535013noreply@blogger.com0tag:blogger.com,1999:blog-542939838580495592.post-60908275674957012582012-08-22T15:47:00.002+12:002012-09-19T07:54:36.926+12:00Fraud, greed, and lies: the origin of the anti-vaccination movement<i style="font-family: georgia; text-align: justify;">Recently, a good friend of mine had her first baby. He is now in the process of getting his first vaccinations, and so my friend has suddenly become exposed to the anti-vaccination movement. She is, understandably, worried: should she or should she not vaccinate? Is there any truth to what the anti-vaccination proponents are saying? Why are vaccines suddenly seen as the worst thing you could do to your child? How did all this start? Who is Andrew Wakefield?</i><br />
<div class="Publishwithline">
<div style="text-align: justify;">
<br /></div>
</div>
<div class="MsoNormal" style="margin-bottom: 0pt;">
<div style="text-align: justify;">
<span style="font-family: Georgia, 'Times New Roman', serif;">Vaccination is the administration of an antigenic - </span><b style="font-family: Georgia, 'Times New Roman', serif;">anti</b><span style="font-family: Georgia, 'Times New Roman', serif;">body </span><b style="font-family: Georgia, 'Times New Roman', serif;">gen</b><span style="font-family: Georgia, 'Times New Roman', serif;">erating - material, that is, something that stimulates the immune system to produce antibodies against it. These antibodies can recognize and neutralize this foreign material, marking it for destruction by other immune cells. By using material from a killed or weakened pathogen (or sometimes even just a portion of it), the immune system can be primed to deal with this invader. When an infection then occurs sometime in the future, the immune system is ready to deal with it quickly and efficiently, at the least reducing the severity of the symptoms or the duration of the disease, and in many cases even completely preventing it from developing.</span><br />
<span class="Apple-style-span" style="font-size: small;"><span class="Apple-style-span" style="font-family: georgia;"><br /></span></span><span class="Apple-style-span" style="font-size: small;"><span class="Apple-style-span" style="font-family: georgia;">While objections to vaccines have been around as long as vaccines themselves, the beginning of the modern anti-vaccination movement can be pinpointed with accuracy: the publication of a <a href="http://briandeer.com/mmr/lancet-paper.pdf">paper</a></span></span><span class="Apple-style-span" style="font-size: small;"><span class="Apple-style-span" style="font-family: georgia;"> in the British medical journal Lancet in February of 1998. It was written by a laboratory researcher, Dr Andrew Wakefield, and co-authored by a dozen other doctors, reporting on the cases of 12 anonymous children with developmental disorders who were admitted to a paediatric bowel unit at the Royal Free hospital in Hampstead, north London, between July 1996 and February 1997. The publication of the paper was followed by a <a href="http://briandeer.com/mmr/royal-free-press-1998.pdf">press release</a> </span></span><span class="Apple-style-span" style="font-size: small;"><span class="Apple-style-span" style="font-family: georgia;">and further publicity that received huge media attention and began the concerted attack on vaccinations.</span></span><br />
<span style="font-family: Georgia, 'Times New Roman', serif;"><br /></span><span style="font-family: Georgia, 'Times New Roman', serif;">In a 20 minute video press release, later <a href="http://www.nature.com/embor/journal/v7/n12/full/7400862.html">criticised</a> as "science by press conference", Wakefield called for a suspension of the triple measles, mumps, and rubella (<a href="http://en.wikipedia.org/wiki/MMR_vaccine">MMR</a>) vaccine, suggesting it was linked to the development of autism in children. </span><span style="font-family: georgia;">A furore around vaccines exploded in the media and on the internet, where the anti-vaccine argument gained significant traction. The uncritical or at times blatantly irresponsible reporting by numerous media outlets, as well as television talk shows giving vaccine opponents a platform, led to a widespread (and mostly unchallenged) spread of this idea. </span><span style="font-family: georgia;">As a consequence, vaccination rates - of not just MMR, but all vaccines - in the next decade have fallen, a trend that is world-wide:</span></div>
</div>
<div class="MsoNormal" style="margin-bottom: 0pt;">
<div class="MsoNormal" style="margin-bottom: 0pt;">
<ul>
<li><span style="font-family: georgia;">In the UK, official figures for 2003/2004 have <a href="http://news.bbc.co.uk/2/hi/health/3683930.stm">shown</a> a drop in MMR vaccinations to 80% from a peak coverage of 92% in 1995-6 (just before Wakefield's publication).</span></li>
</ul>
<ul>
<li><span style="font-family: georgia;">The American Council on Science and Health <a href="http://www.acsh.org/factsfears/newsid.3051/news_detail.asp">warned</a> that </span><span style="font-family: georgia;">childhood vaccination rates against measles, mumps, and rubella (MMR) fell nearly 3 percentage points in 2009 from the year before: almost 10 percent of American children are not vaccinated from serious diseases, which include diphtheria, tetanus, and pertussis.</span></li>
</ul>
<ul>
<li><span style="font-family: georgia;"><span style="font-family: georgia;">In 2010, </span><span style="font-family: georgia;">Medicare in Australia </span><a href="http://nz.news.yahoo.com/a/-/archive/7305739/child-vaccination-rates-plunge/">reports</a><span style="font-family: georgia;"> that </span><span style="font-family: georgia;"> the number of youngsters not fully immunised in the national program has doubled over the past five years, and the number</span><span style="font-family: georgia;"> of children whose parents have registered as conscientious objectors to vaccinations also rose by 68 per cent in that time.</span></span></li>
</ul>
<ul>
<li><span style="font-family: georgia;">Also in 2010, Switzerland had <a href="http://www.swissinfo.ch/eng/swiss_news/Measles_is_still_a_sore_spot_for_the_Swiss.html?cid=8736280">one of the lowest</a> immunization rates in Europe, with only 71% of children receiving the recommended two doses of the measles vaccine. </span></li>
</ul>
<div style="text-align: justify;">
<span style="font-family: georgia;">This drop in vaccination is not without consequence. </span><span style="font-family: Georgia, Times New Roman, serif;">Herd immunity </span><span style="font-family: georgia;">is the resistance</span><span style="font-family: georgia;"> to the spread of infectious disease in a group because susceptible members are few, making transmission from an infected member unlikely. </span><span style="font-family: georgia;"> To achieve h</span><span style="font-family: georgia;">erd immunity,</span><span style="font-family: georgia;"> 75% to 95% of people must be vaccinated. The exact level of vaccination required depends on the disease, how contagious it is, and how it is transmitted. In many places the level of vaccination has dropped below the herd immunity threshold, and the effects are painfully apparent: the incidence of fully preventable (and once considered vanquished!) diseases such as measles and pertussis (whooping cough) is on the rise.</span></div>
<br />
<div style="text-align: justify;">
<span style="font-family: georgia;">California </span><a href="http://www.cdph.ca.gov/Pages/NR10-041.aspx" style="font-family: georgia;">reported</a><span style="font-family: georgia;"> a whooping cough epidemic in 2010 that may have been the worst in 50 years. Measles is </span><a href="http://www.3news.co.nz/Measles-outbreaks-on-the-rise-across-Europe/tabid/417/articleID/234968/Default.aspx" style="font-family: georgia;">on the rise</a><span style="font-family: georgia;"> in Europe, and England </span><a href="http://www.bbc.co.uk/news/health-13561766" style="font-family: georgia;">reported</a><span style="font-family: georgia;"> a 10-fold rise in cases in 2011. Most recently, southern Alberta, Canada, </span><a href="http://www.edmontonjournal.com/health/Simons+fashioned+killer+puts+Alberta+children+risk/6989299/story.html" style="font-family: georgia;">is in the grips</a><span style="font-family: georgia;"> of an ugly whooping cough outbreak. </span><a href="http://www.nzherald.co.nz/nz/news/article.cfm?c_id=1&objectid=10811494" style="font-family: georgia;">So is</a><span style="font-family: georgia;"> New Zealand.</span></div>
<div style="text-align: justify;">
<span style="font-family: georgia;"><br /></span></div>
<div style="text-align: justify;">
<span style="font-family: georgia;">These diseases are not innocuous. Measles complications can affect one in 15 children infected, and can include bronchitis, seizures, and encephalitis (which may be fatal). Pertussis is especially risky for very young babies - newborns under two months have a 1 in 100 change of dying from the disease, and children up to 12 months have a 1 in 200 chance. Serious complications can include pneumonia, encephalopathy, seizures, and failure to thrive. Pertussis can also cause severe paroxysm-induced cerebral hypoxia and apnea (when the baby is coughing so hard it can't breathe and the brain is starved of oxygen, leading to brain damage).</span></div>
<div style="text-align: justify;">
<span style="font-family: georgia;"><br /></span></div>
<div style="text-align: justify;">
<span style="font-family: georgia;">So what is the science behind Wakefield's claim to stop vaccinating children?</span><br />
<span class="Apple-style-span" style="font-size: small;"><span class="Apple-style-span" style="font-family: georgia;"><br /></span></span><span class="Apple-style-span" style="font-size: small;"><span class="Apple-style-span" style="font-family: georgia;">An investigation into Wakefield's research by the journalist </span></span><a href="http://briandeer.com/"><span class="Apple-style-span" style="font-size: small;"><span class="Apple-style-span" style="font-family: georgia;">Brian Deer</span></span></a><span class="Apple-style-span" style="font-size: small;"><span class="Apple-style-span" style="font-family: georgia;">, of the </span></span><span class="Apple-style-span" style="font-size: small;"><span class="Apple-style-span" style="font-family: georgia;">Sunday Times</span></span><span class="Apple-style-span" style="font-size: small;"><span class="Apple-style-span" style="font-family: georgia;">, revealed an astounding scandal. As Wakefield was warning parents to avoid MMR, and publishing papers claiming a link between vaccines and autism, he was in fact being funded by Richard Barr, a solicitor hoping to raise a class action law suit against the company manufacturing the vaccine. After an initial payment of £55,000, Barr paid Wakefield out of the UK legal aid fund (run to give poorer people access to justice) a sum eventually totalling £435,643 (more than eight times Wakefield's reported annual salary).</span></span></div>
<span class="Apple-style-span" style="font-size: small;"></span></div>
</div>
<div class="MsoNormal" style="margin-bottom: 0pt;">
<div style="text-align: justify;">
<br /></div>
</div>
<div class="MsoNormal" style="margin-bottom: 0pt;">
<div style="text-align: justify;">
<span class="Apple-style-span" style="font-size: small;"><span class="Apple-style-span" style="font-family: georgia;">The children themselves, supposedly routine patients at the Royal Free Hospital, turned out to have been recruited through MMR campaign groups, and their parents were contacts or clients of the lawyer Barr. In addition, nine months before the publication of the paper, Wakefield filed a series of patents, including <a href="http://briandeer.com/wakefield/vaccine-patent.htm">one</a></span></span><span class="Apple-style-span" style="font-size: small;"><span class="Apple-style-span" style="font-family: georgia;"> for a single - supposedly safer - measles vaccine, "which only stood any prospect of success if confidence in MMR was damaged."</span></span></div>
</div>
<div class="MsoNormal" style="margin-bottom: 0pt;">
<div style="text-align: justify;">
<span class="Apple-style-span" style="font-size: small;"><span class="Apple-style-span" style="font-family: georgia;">None of these </span></span><i><span class="Apple-style-span" style="font-size: small;"><span class="Apple-style-span" style="font-family: georgia;">substantial</span></span></i><span class="Apple-style-span" style="font-size: small;"><span class="Apple-style-span" style="font-family: georgia;"> conflicts of interest were reported in the paper, or declared to the journal Lancet.</span></span></div>
</div>
<div class="MsoNormal" style="margin-bottom: 0pt;">
<div style="text-align: justify;">
<br /></div>
</div>
<div class="MsoNormal" style="margin-bottom: 0pt;">
<div style="text-align: justify;">
<span class="Apple-style-span" style="font-size: small;"><span class="Apple-style-span" style="font-family: georgia;">The conflict of interest was just the beginning, as</span></span><span style="font-family: georgia;"> </span><span style="font-family: georgia;">further investigation revealed worrying ethical issues as well. Research on human subjects is strictly governed by national and international standards, including the <a href="http://en.wikipedia.org/wiki/Declaration_of_Helsinki">Declaration of Helsinki</a> which is </span><span style="font-family: georgia;">a set of ethical principles regarding human experimentation </span><span style="font-family: georgia;">developed for the medical community by the World Medical Association (WMA). No reputable hospital review board would have endorsed Wakefield's proposed "fishing expedition" - which included a <a href="http://briandeer.com/mmr/royal-quiz.htm">battery</a> of invasive and distressing procedures like lumbar punctures and colonoscopies. Without approval, however, no reputable medical journal would publish the findings. So Wakefield simply <a href="http://briandeer.com/mmr/royal-table.htm">lied</a> in the paper, stating ethical approval had been obtained.</span></div>
<br />
<div style="text-align: justify;">
<span style="font-family: georgia;">In addition, he showed further unethical behaviour by buying (for</span> <span style="font-family: georgia;">£</span><span style="font-family: georgia;">5) blood from children at a birthday party, completely ignoring the inappropriateness of the setting. Later, he would go on to <a href="http://briandeer.com/wakefield/birthday-blood.htm">describe</a> this event in a public forum, making a joke out of children fainting and vomiting, </span><span style="font-family: georgia;">showing callous disregard for any distress or pain to the children.</span></div>
<br />
<div style="text-align: justify;">
<span style="font-family: georgia;">As if the blatant conflict of interest, and the entirely unethical way this "research" was conducted wasn't enough, t</span><span class="Apple-style-span" style="font-size: small;"><span class="Apple-style-span" style="font-family: georgia;">he actual data presented in the Lancet paper - the article that started the whole vaccination and autism debate - was in fact to a large degree manufactured by Wakefield himself. In most of the 12 cases reported, the <i>actual </i>hospital and GP records <i>differed </i>to what was described in the Lancet. The research paper claimed autism-like symptoms began within days of the vaccination, but in all cases but one such concerns were raised significantly before vaccination. The majority of cases were presented in the Lancet as having an abnormal gut; hospital pathologists had previously <a href="http://briandeer.com/solved/bmj-pathology.pdf">declared them</a> fully normal</span></span><span class="Apple-style-span" style="font-size: small;"><span class="Apple-style-span" style="font-family: georgia;">.</span></span></div>
</div>
<div class="MsoNormal" style="margin-bottom: 5pt;">
<div style="text-align: justify;">
<br /></div>
</div>
<div class="MsoNormal" style="margin-bottom: 0pt;">
<div style="text-align: justify;">
<span class="Apple-style-span" style="font-size: small;"><span class="Apple-style-span" style="font-family: georgia;">So, let's be clear: this supposed link between vaccines and autism <b>was completely fabiracted </b>by Wakefield in order to profit from the fallout. <a href="http://www.sciencedirect.com/science/article/pii/S0140673699001609">Numerous</a> </span></span><span class="Apple-style-span" style="font-size: small;"><span class="Apple-style-span" style="font-family: georgia;"><a href="http://www.sciencedirect.com/science/article/pii/S0140673699012398">studies</a> <a href="http://www.sciencedirect.com/science/article/pii/S0264410X01000974">have</a> <a href="http://www.sciencedirect.com/science/article/pii/S1045187003000347">tried</a> <a href="http://www.sciencedirect.com/science/article/pii/S0264410X12005828">to</a> <a href="http://www.cdc.gov/vaccinesafety/00_pdf/VSD_Chart_of_Autism_Studies-Updated_Aug_18_09.pdf">replicate</a> <a href="http://www.ncbi.nlm.nih.gov/pubmed/14761240">his</a> <a href="http://www.sciencedirect.com/science/article/pii/S1045187003000347">findings</a>, but have always failed to find any link. A number of health authorities (including the <a href="http://briandeer.com/solved/dateline-aap.pdf">American Academy of Pediatrics</a>, <a href="http://www.cdc.gov/vaccinesafety/concerns/autism/index.html">Centers for Disease Control</a>, the <a href="http://www.who.int/vaccine_safety/topics/mmr/mmr_autism/en/">World Health Organization</a>, and the </span></span><a href="http://books.nap.edu/openbook.php?record_id=10997&page=R1"><span style="font-family: georgia;">Institute of Medicine of the </span><span style="font-family: Georgia, Times New Roman, serif;">National Academies</span></a><span style="font-family: georgia;">)</span><span style="font-family: georgia;">, have <a href="http://onlinelibrary.wiley.com/doi/10.1002/14651858.CD004407.pub3/abstract">reviewed</a> all the available evidence, and every single time the conclusion is the same:</span><br />
<span style="font-family: georgia;"><br /></span><span style="font-family: georgia;"></span>
<br />
<div style="text-align: center;">
<span style="font-family: georgia;"><i>The body of epidemiological evidence does NOT support a causal relationship between the MMR vaccine and autism. </i></span></div>
<div style="text-align: center;">
<span style="font-family: georgia;"><i><br /></i></span></div>
<br />
<span style="font-family: georgia;">More and more evidence piled up against the conclusions of Wakefield's paper, and slowly, the scientific record was put straight. First, in March of 2004, 10 out of the 12 authors of the original paper (one could not be contacted) </span><a href="http://www.thelancet.com/journals/lancet/article/PIIS0140-6736(04)15715-2/fulltext" style="font-family: georgia;">published a formal retraction</a><span style="font-family: georgia;"> of the conclusions of the paper:</span></div>
</div>
<div class="MsoNormal" style="margin-bottom: 0pt;">
<span class="Apple-style-span" style="font-family: georgia;"><span class="Apple-style-span" style="font-size: small;"></span></span></div>
<blockquote>
<span class="Apple-style-span" style="font-size: small;"><span class="Apple-style-span" style="font-family: georgia;"><i>We wish to make it clear that in this paper no causal link was established between MMR vaccine and autism as the data were insufficient. However, the possibility of such a link was raised and consequent events have had major implications for public health. In view of this, we consider now is the appropriate time that we should together formally retract the interpretation placed upon these findings in the paper, according to precedent</i>.</span></span></blockquote>
<span class="Apple-style-span" style="font-size: small;"><span class="Apple-style-span" style="font-family: georgia;">Then in February of 2010, the Lancet finally formally <a href="http://www.thelancet.com/journals/lancet/article/PIIS0140-6736(10)60175-4/fulltext">retracted the whole paper</a>:</span></span><span class="Apple-style-span" style="line-height: 19px;"></span><span class="Apple-style-span" style="font-size: small;"><span class="Apple-style-span" style="font-family: georgia;"></span></span><br />
<blockquote class="tr_bq">
<span class="Apple-style-span" style="font-size: small;"><span class="Apple-style-span" style="font-family: georgia;"><i>..., it has become clear that several elements of the 1998 paper by Wakefield </i>et al.<i> are incorrect, contrary to the findings of an earlier investigation. In particular, the claims in the original paper that children were “consecutively referred” and that investigations were “approved” by the local ethics committee have been proven to be false. Therefore we fully retract this paper from the published record.</i></span></span></blockquote>
<div style="text-align: justify;">
<span class="Apple-style-span" style="font-size: small;"><span class="Apple-style-span" style="font-family: georgia;">This was in response to the results of an inquiry by the British General Medical Council, convened in July 2007. In a decision released almost three years later, t</span></span><span class="Apple-style-span" style="font-size: small;"><span class="Apple-style-span" style="font-family: georgia;">he General Medical Council fitness to practice panel found Wakefield guilty of multiple instances of serious professional misconduct. The Panel states that he was dishonest and misleading, that he breached his duties, that he repeatedly breached fundamental principles of research medicine, that he failed to ensure that the factual information contained in the paper was true and accurate, that he was intentionally dishonest, irresponsible and misleading, and that his actions were contrary to the clinical interest of the patient, and an abuse of his position of trust as a medical practitioner. The Panel <a href="http://briandeer.com/solved/gmc-wakefield-sentence.pdf">concluded</a> that his conduct brought the medical profession into disrepute.</span></span><span class="Apple-style-span" style="font-size: small;"><span class="Apple-style-span" style="font-family: georgia;"> Finally, on May 24th, 2010, he was <a href="http://www.guardian.co.uk/society/2010/may/24/mmr-doctor-andrew-wakefield-struck-off">struck off</a> the UK medical register, revoking his license to practice medicine in the UK.</span></span></div>
<div class="MsoNormal" style="margin-bottom: 0pt;">
<br /></div>
<div class="MsoNormal" style="margin-bottom: 0pt;">
<div style="text-align: justify;">
<span style="font-family: georgia; text-align: center;">Every aspect of Dr Wakefield's claim has been disproven and discredited, numerous times over. Yet the meme persists, possibly because it </span><span style="font-family: georgia;">provides a simple explanation to a complex </span><span style="font-family: georgia; text-align: center;">problem, provides and answer that so many parents desperately search for, and gives something to blame. But the truth is: t</span><span style="font-family: georgia; text-align: center;">here is no</span><i style="font-family: georgia; text-align: center;"> </i><span style="font-family: georgia; text-align: center;">link between vaccines and autism - there never was. So vaccinate your kids!</span></div>
</div>
Joanna Wojnarhttp://www.blogger.com/profile/15686958330818535013noreply@blogger.com0