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Monday, May 7, 2012
Pathogens that feed off human blood
Bacteria may be tiny little micro-organisms but like any other living creature there are certain molecules that they need for survival. No matter what niche a bacterial colony occupies, it eventually requires a source of iron. For bacteria that live within the human body, there is one incredibly iron-rich molecule that circulates throughout the human body and can be found permeating the tissues.
Haemoglobin ? the molecule that gives blood its red colour and is used to transport oxgyen through the body.
The structure of haemoglobin, by Richard Wheeler (Zephyris) 2007.
The image above (credit link) shows the structure of the haemoglobin molecule. It consists of four sub-chains (shown in red and blue) each of which carries an iron containing ?haem co-factor? which you can just about see in the diagram as the spikey green things. These haemoglobin molecules are packed tight into red blood cells, so tightly that the red blood cells don?t even have a nucleus but are just haemoglobin carrying machines. The lack of nucleus means that they can?t grown or divide (or do anything much), so after being put together in the bone marrow and circulating the blood for around three months red blood cells are?discreetly?removed and replaced.
All of this circulating iron is a great opportunity for pathogenic bacteria, who have developed varies systems to get hold of it. Firstly they have to break down the red blood cells, usually by secreting various chemicals that break up the cell membrane, releasing the haemoglobin. Then they have to bind to the haemoglobin via specialised receptors on their cell surface. Once bound, the haemoglobin passes through the bacterial cell wall and into the interior of the cell. For bacteria with two cell membranes (Gram negative bacteria) this is a complex task involving various different proteins, transporters, and use of the proton-motive force. For bacteria with one large thick cell membrane (Gram positive bacteria) ?some sort of protein relay process seems to be involved, which uses far less energy. Greater detail on both these processes can be found in the references below.
A very simply schematic of the difference between Gram positive bacteria (top) and Gram negative (bottom). Original uploader was Graevemoore at en.wikipedia.
Once inside the bacterium, the haemoglobin is broken down to release the precious iron that it carries. This is more dangerous than it sounds, because the iron in haemoglobin is carrying oxygen, which means that there is potential for reactive oxgyen species to be released and cause havoc inside the cell. Not only that but in some bacteria the ?haem co-factor? itself can be toxic. Some bacteria contain special enzymes called ?Haem oxygenases? which deal with the oxgyen species, while others sequester the haem in vacuoles away from the rest of the cell, or turn on exporter molecules. It?s not quite clear whether the exporters are taking away the haem or some other toxic product, but they are vital for preventing the toxic effects of haemoglobin within the bacteria.
The whole process of extracting iron from haemoglobin is actually fraught with dangers for the bacteria. The process requires all sorts of special molecules and transporters which don?t feature in human cells, which makes them a prime target for the immune system to recognise an invading element. In particular the haemoglobin binding proteins, which are a bit like a large red flag labelled ?invader? sticking out of the bacterial cell surface. Not only that, but they are quite energy expensive to run, particularly for the Gram negative cells. In consequence, the bacteria tend to only activate this system when they are running particularly low on iron, and there are no other available sources around.
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Ref 1: Pishchany G, & Skaar EP (2012). Taste for blood: hemoglobin as a nutrient source for pathogens. PLoS pathogens, 8 (3) PMID: 22412370
Ref 2: Pishchany, G., McCoy, A., Torres, V., Krause, J., Crowe, J., Fabry, M., & Skaar, E. (2010). Specificity for Human Hemoglobin Enhances Staphylococcus aureus Infection Cell Host & Microbe, 8 (6), 544-550 DOI: 10.1016/j.chom.2010.11.002
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Sunday, May 6, 2012
Switched On: Competing by hook or by Nook
Each week Ross Rubin contributes Switched On, a column about consumer technology.
Microsoft has a long history of supporting bitter rivals -- even those that have long publicly disparaged the company, offering funds to Nokia, Corel and, most famously, Apple. It also has a long history of supporting e-reading. Prior to ending development last year, the company offered its Microsoft Reader software for about a decade -- first on handheld devices using Windows CE and Windows Mobile and later on desktop Windows. Those two traditions intersected yesterday as Microsoft invested in a new Nook e-book business designed to compete better against Apple and especially Amazon.com.
Continue reading Switched On: Competing by hook or by Nook
Switched On: Competing by hook or by Nook originally appeared on Engadget on Sun, 06 May 2012 18:28:00 EDT. Please see our terms for use of feeds.
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Sun UV Protector App?When it?s Time to Come in out of the Sun
Aratos Technologies wants to tell you when to come in out of the sun, and with the Sun UV Protector App for iPhones, ?it won’t be hard to do. The UV factor in Las Vegas isn’t the same UV factor in Seattle. ?And it’s hard to always know the right protection to use. ?The Sun [...]
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Saturday, May 5, 2012
Romney says he wanted gay spokesman to stay on job
PITTSBURGH (AP) ? Walking a careful line, Republican presidential candidate Mitt Romney said Friday he had wanted an openly gay spokesman who resigned from his campaign this week to stay on. Hours later, he worked to court the party's conservative wing by meeting with former rival Rick Santorum.
In an interview with Fox News, Romney said his campaign hires people "not based upon their ethnicity, or their sexual preference or their gender but upon their capability." He called the former spokesman, Richard Grenell, a "capable individual" and said many senior campaign aides urged him not to leave.
Romney struggled through the primary to court conservatives, particularly evangelical Christian voters, and many flocked to Santorum. Now the presumptive nominee, Romney is trying to court the base of the party without alienating independent, swing and other voters he will need to beat Democratic President Barack Obama in November.
Details on what Romney and Santorum discussed were not immediately available. Santorum did not offer Romney his endorsement.
The Grenell flap shows how carefully Romney is treading on the subject. Grenell was hired in late April to speak for Romney on national security and foreign policy issues.
A vocal supporter of gay marriage, which Romney opposes, Grenell resigned Tuesday after conservative critics raised questions about his sexual orientation. His departure also came after he was conspicuously absent from a week of campaign discussion dominated by national security issues, in part because of the one-year anniversary of the death of Osama bin Laden.
Grenell said in a statement that he felt his ability to do his job was "greatly diminished by the hyper-partisan discussion of personal issues."
His departure sparked an outcry among gay rights groups. Romney's comments were his first on the issue, and he did not hit back at Grenell's critics or defend him. He said it was Grenell's decision to leave the campaign.
In a separate appearance Friday on MSNBC, Romney spokesman Eric Fehrnstrom insisted that Romney previously had denounced the "voices of intolerance that expressed themselves during this debate."
At an appearance at the Values Voter Summit in October, Fehrnstrom said Romney "denounced some of the poisonous language that was being used by some of the same people" who criticized Grenell.
"We should remember that decency and civility are values too," Romney said at that conference, referring to Bryan Fischer, an activist at the American Family Association, which promotes traditional family values. "One of the speakers who will follow me today has crossed that line, I think. Poisonous language doesn't advance our cause."
At the conference, Romney also implicitly criticized figures on the religious right who were attacking his Mormon faith, including evangelical pastor Robert Jeffress. At the time, Jeffress was supporting Texas Gov. Rick Perry, who was running against Romney in the Republican presidential primary.
Fischer has made anti-gay remarks in the past and was one of the people who criticized Grenell. "Romney picks out & loud gay as a spokesman. If personnel is policy, his message to the pro-family community: drop dead," Fischer said on Twitter after Grenell was hired.
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Dundee student designs Passive Play toy cube to stimulate parent interaction with autistic children
A University of Dundee scholar has been working on a wonderful tool that aims to evoke the emotional connection between children with autism and their parents. While we've seen novelties like the My Keepon in the past, any addition to the cause is always a pleasant one, and the Passive Play's no exception. The concept comes in the form of an interactive toy cube for the kid (pictured above), which pairs up with an iOS app and allows the parent to see any interaction the little one is having with the device. Passive Play's creator, Tom Kirkman, says his inspiration comes from "wanting to learn more about autism," and in case you happen to be in the UK, he'll be showing off the project at Dundee University later this month. For all those details, be sure to check out the PR after the break.
Dundee student designs Passive Play toy cube to stimulate parent interaction with autistic children originally appeared on Engadget on Fri, 04 May 2012 18:47:00 EDT. Please see our terms for use of feeds.
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Power Calculator and Power Systems - IdeaMarketers.com
Power calculator
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Power calculator helps you select the portable generator that is right for you. You may start by using Power calculator to calculate power needs. You can then you can select the category of portable generators you may need to buy.
If you want to keep your appliances working when the power goes out in a winter storm, you don't want to be caught with a generator that's too small for the job. Since portable generators are sized by their output in watts, this means you need to know how many watts your household appliances consume. You'll need to make an inventory of the items you want to keep running, find out how many watts of electricity each needs, then use power calculator that provides for that need.
Power calculator protects your appliances during an emergency power outage by calculating the appropriate generator size for your needs.
Power Systems
Almost all electrical power systems use relays for control and safety. Without them, safe control of power would be impossible, whether it's a small system for personal use or an electric plant to power an entire city.
Installing power systems in your home can make power outages less of an inconvenience and can provide a critical safety element in event of a natural disaster
Home power systems need to have sufficient capacity to power the necessary electrical systems for a significant amount of time with a protected fuel supply. Consider what you need to power, how long it will take you to restore power, and how you will fuel the generators.
Power Washers
is a handy machine It can be used to clean the siding, driveways, deck, gutters and a variety of other things around the home, Some homeowners even clean their roof shingles with a power washer. If it's outside and dirty, you can probably of useto clean it.
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