Most any medical device implanted in the body — or one that comes into contact with flowing blood, such as a dialysis machine — may also present two critical challenges for the patient: blood clotting and bacterial infection.In a study reported in Nature Biotechnology, a team of Harvard scientists and engineers has developed a new surface coating for medical devices using materials already approved by the Food and Drug Administration (FDA). The researchers noted that the coating repelled blood from more than 20 medically relevant substrates (glass, plastic, and metal) and also suppressed biofilm formation.The team also implanted medical-grade tubing and catheters coated with the material in large blood vessels in pigs. The coating prevented blood from clotting for at least eight hours without the use of blood thinners like heparin, which can cause side effects, such as excessive bleeding.“Devising a way to prevent blood clotting without using anticoagulants is one of the holy grails in medicine,” said Don Ingber, director of Harvard’s Wyss Institute for Biologically Inspired Engineering and senior author of the study. Ingber is also the Judah Folkman Professor of Vascular Biology at Harvard Medical School and Boston Children’s Hospital, as well as professor of bioengineering at Harvard’s School of Engineering and Applied Sciences (SEAS).The idea for the coating evolved from SLIPS (slippery-liquid-infused porous surfaces), a pioneering surface technology developed by co-author Joanna Aizenberg, who is a Wyss Institute core faculty member and the Amy Smith Berylson Professor of Materials Science at SEAS.These glass slides were dipped in blood to demonstrate the effectiveness of the TLP coating. Blood does not adhere to the TLP-treated slide on the right.SLIPS was inspired by the slippery surface of the carnivorous pitcher plant. It repels nearly any material it contacts, and the liquid layer on its surface provides a barrier against everything from ice to crude oil and blood.“Traditional SLIPS uses porous, textured surface substrates to immobilize the liquid layer, whereas medical surfaces are mostly flat and smooth — so we further adapted our approach by capitalizing on the natural roughness of chemically modified surfaces of medical devices,” said Aizenberg, who leads the Wyss Institute’s adaptive materials group. “This is yet another incarnation of the highly customizable SLIPS platform that can be designed to create slippery, nonadhesive surfaces on any material.”In a two-step surface-coating process, the Wyss team chemically attached a monolayer of perfluorocarbon, which is similar to Teflon, then added a layer of liquid perfluorocarbon. The team calls the tethered perfluorocarbon plus the liquid layer a “tethered-liquid perfluorocarbon” surface, or TLP.The TLP coating achieved the following results:TLP-treated medical tubing stored for more than a year under normal temperature and humidity conditions still prevented clot formation.The TLP surface remained stable under the full range of clinically relevant physiological shear stresses, or rates of blood flow seen in catheters and central lines, all the way up to dialysis machines.The TLP coating repelled the components of blood that cause clotting (fibrin and platelets).When bacteria called Pseudomonas aeruginosa were grown in TLP-coated medical tubing for more than six weeks, less than one in a billion bacteria were able to adhere.The researchers even tested a TLP-coated surface with a gecko — the superstar of sticking whose footpads contain thousands of hairlike structures with tremendous adhesive strength. The gecko was unable to hold on.“We were wonderfully surprised by how well the TLP coating worked, particularly in vivo without heparin,” said one of the co-lead authors, Anna Waterhouse, a Wyss Institute postdoctoral fellow. “Usually the blood will start to clot within an hour in the extracorporeal circuit, so our experiments really demonstrate the clinical relevance of this new coating.”The project was funded by the Defense Advanced Research Projects Agency (DARPA) and the Wyss Institute.
– Advertisement – With a vast majority of votes counted, Mr. Tillis was leading by just under 100,000 votes, according to Edison Research, in an election that drew more voters and political spending than any in the state’s history. Mr. Tillis took a lead on election night and never lost it, but because of an influx of mail-in ballots, the result was still not official on Thursday, long after most other races were called.In a pre-emptive victory speech last week, Mr. Tillis said North Carolinians were “letting everybody know that the truth still does matter, letting everybody know that character still matters, and letting everybody know that keeping your promises still matters.” – Advertisement – The result was a relief for Republicans, who viewed the seat as a potential tipping point whose loss could have cost them control of the Senate. A win by Mr. Tillis would give Republicans 49 Senate seats to Democrats’ 48. Another race remained uncalled in Alaska, where Senator Dan Sullivan, a Republican, is favored to win.Either way, Mr. Tillis’s apparent victory only increased the already towering stakes of a pair of January Senate runoffs in Georgia, where a clean sweep by Democrats could hand them a working majority, with Vice President-elect Kamala Harris empowered to cast tiebreaking votes.Republicans view that outcome as a long shot in a state they have historically dominated, but both parties were already pouring tens of millions of dollars into the races and honing messages to try to frame the holiday-season fight. Cal Cunningham, the Democrat challenging Senator Thom Tillis, Republican of North Carolina, conceded the race on Tuesday after a protracted vote count, as the incumbent appeared headed for a narrow victory in a crucial swing state that would bolster his party’s hold on the Senate.Mr. Tillis, 60, had been one of the Democrats’ top targets this year, a decidedly unpopular first-term Republican in a fast-growing and increasingly competitive state. But he was able to capitalize on unexpected Republican strength in North Carolina to outrun Mr. Cunningham, who was damaged by late revelations of an extramarital affair.- Advertisement – Mr. Cunningham said in a statement on Tuesday that the election results suggested “there remain deep political divisions in our state and nation.” He added that he would “always be proud of the work we did together to lift up the voices of North Carolinians who feel left behind by our politics.”- Advertisement –
A use for bad breath?Hydrogen sulphide, the gas famed for generating the stench in stink bombs, flatulence and bad breath, has been harnessed by stem cell researchers in Japan.Their study, in the Journal of Breath Research, investigated using it to help convert stem cells from human teeth into liver cells. The scientists claimed the gas increased the purity of the stem cells.Small amounts of hydrogen sulphide are made by the body.It is also produced by bacteria and is toxic in large quantities.TherapyA group in China has already reported using the gas to enhance the survival of mesenchymal stem cells taken from the bone marrow of rats.Researchers at the Nippon Dental University were investigating stem cells from dental pulp – the bit in the middle of the tooth.They said using the gas increased the proportion of stem cells which were converted to liver cells when used alongside other chemicals. The idea is that liver cells produced from stem cells could be used to repair the organ if it was damaged.Dr Ken Yaegaki, from Nippon Dental University in Japan, said: “High purity means there are less ‘wrong cells’ that are being differentiated to other tissues, or remaining as stem cells.”One of the concerns with dental pulp as a source of stem cells is the number that can be harvested.However, the study did not say how many cells were actually produced. Prof Chris Mason, a specialist in regenerative medicine at University College London, said: “It would be interesting to see how hydrogen sulphide works with other cells types.”BBC News Tweet Share Sharing is caring! Share HealthLifestyle Chemical in bad breath ‘influences’ dental stem cells by: – February 27, 2012 7 Views no discussions Share