Nature News

Diskutera fysik, kemi, biologi, samt direkta tillämpningar såsom teknik och medicin.
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Re: Malariavaccin

Inlägg av Tryggve » tis 10 sep 2013, 17:58

JonLan skrev:
Tryggve skrev:Detta låter ju synnerligen lovande, måste jag säga. Hoppas att det fungerar.
Intressant proof of concept, men jag tvivlar på att det här vaccinet kommer kunna bli aktuellt för massvaccination, då det uppenbarligen är väldigt omständigt att framställa, distribuera och administrera. Ska bli intressant att se om resultaten på något sätt kan bidra till utvecklingen av ett enklare proteinbaserat vaccin.
Sant, men även ett dyrt vaccin är väl bättre än inget alls. Man kan ju tänkas sig att man använder vaccinet ihop med andra åtgärder.

Men förhoppningsvis kan man vidareutveckla detta.

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Henrietta Lacks

Inlägg av Tryggve » tis 10 sep 2013, 18:04

Det verkar som om det har kommit till stånd en överenskommelse från de anhöriga till Henrietta Lacks om att publicera genomiska data från cellinjen.

Dock så handlar det ju inte om någon som helst typ av ekonomisk kompensation.

Deal done over HeLa cell line

Deal done over HeLa cell line

Family of Henrietta Lacks agrees to release of genomic data.

Deborah Lacks wanted answers. In 1974, she asked a leading medical geneticist to tell her about HeLa cells, a tissue-culture cell line derived from the cancer that had killed her mother Henrietta in 1951. The researcher, who was collecting blood from the Lacks family to map HeLa genes, autographed a medical textbook he had written and said that everything she needed to know lay within its dense pages.

It would be more than 30 years before the family got a better explanation.

Now the director of the US National Institutes of Health (NIH), Francis Collins, is trying to make up for decades of slights. Over the past four months, he has met Lacks family members to answer questions and to discuss what should be done with genome data from their matriarch’s cell line.

“We wanted to get a better understanding of what information was going to be out there about Henrietta, and what information was going to be out there about us,” says Henrietta’s grandson David Lacks Jr. (Deborah Lacks died in 2009.) On 7 August, Collins announced that the family has endorsed case-by-case release of the information, subject to approval by a committee that will include family members (see page 141).

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Tarmflora

Inlägg av Tryggve » tis 10 sep 2013, 18:10

En intressant studie som pekar på att bakterieuppsättningen i mag-tarmkanalen har inflytande på fetma. Det är väl i sig inte någon nyhet, men just denna studie var rätt häftig.

Bacteria from lean cage-mates help mice stay slim

Länk till den i studien omnämnda Scienceartikeln.
Gut Microbiota from Twins Discordant for Obesity Modulate Metabolism in Mice
Bacteria from lean cage-mates help mice stay slim

But microbes are only part of the story — the effect also depends on a healthy diet.

Gut bacteria from lean mice can invade the guts of obesity-prone cage-mates and help their new hosts to fight weight gain.

Researchers led by Jeffrey Gordon, a biologist at Washington University in St. Louis, Missouri, set out to find direct evidence that gut bacteria have a role in obesity.

The team took gut bacteria from four sets of human twins in which one of each pair was lean and one was obese, and introduced the microbes into mice bred to be germ-free. Mice given bacteria from a lean twin stayed slim, whereas those given bacteria from an obese twin quickly gained weight, even though all the mice ate about the same amount of food.

The team wondered whether the gut microbiota of either group of mice would be influenced by mice with one type living in close quarters with animals harbouring the other type.

So the scientists took mice with the ‘lean’ microbiota and placed them in a cage with mice with the ‘obese’ type before those mice had a chance to start putting on weight.

“We knew the mice would readily exchange their microbes,” Gordon says — that is, eat each other’s faeces. Sure enough, the populations of bacteria in the obese-type mice changed to match those of their lean cage-mates, and their bodies remained lean, the team writes today in Science1.

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Konvergent evolution

Inlägg av Tryggve » tis 10 sep 2013, 18:14

Konvergent evolution verkar vara något som kan ha skett i hundratals gener.

Convergent evolution seen in hundreds of genes
Convergent evolution seen in hundreds of genes

Bats and dolphins may have developed echolocation via similar mutations.

A new analysis suggests that many genes evolved in parallel in bats and dolphins as each developed the remarkable ability to echolocate.

Different organisms often independently evolve similar observable traits such as anatomical or functional features, but the genetic changes underpinning such 'convergent evolution' are usually different. The new study, published today in Nature1, hints that evolution may be finding the same genetic solutions to a problem more often than previously thought.

“These results imply that convergent molecular evolution is much more widespread than previously recognized,” says molecular phylogeneticist Frédéric Delsuc at the The National Center for Scientific Research (CNRS) at the University of Montpellier in France, who was not involved in the study. What is more, he adds, the genes involved are not just the few, obvious ones known to be directly involved in a trait but a broader array of genes that are involved in the same regulatory networks.

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Re: Nature News

Inlägg av Tryggve » tor 03 okt 2013, 12:58

Detta fanns med i senaste utskicket, låter ju rätt spännande, men än så länge är det ju på experimentstadiet.

Microbial production of short-chain alkanes

Microbial production of short-chain alkanes


Increasing concerns about limited fossil fuels and global environmental problems have focused attention on the need to develop sustainable biofuels from renewable resources. Although microbial production of diesel has been reported, production of another much in demand transport fuel, petrol (gasoline), has not yet been demonstrated. Here we report the development of platform Escherichia coli strains that are capable of producing short-chain alkanes (SCAs; petrol), free fatty acids (FFAs), fatty esters and fatty alcohols through the fatty acyl (acyl carrier protein (ACP)) to fatty acid to fatty acyl-CoA pathway. First, the β-oxidation pathway was blocked by deleting the fadE gene to prevent the degradation of fatty acyl-CoAs generated in vivo. To increase the formation of short-chain fatty acids suitable for subsequent conversion to SCAs in vivo, the activity of 3-oxoacyl-ACP synthase (FabH)1, which is inhibited by unsaturated fatty acyl-ACPs2, was enhanced to promote the initiation of fatty acid biosynthesis by deleting the fadR gene; deletion of the fadR gene prevents upregulation of the fabA and fabB genes responsible for unsaturated fatty acids biosynthesis3. A modified thioesterase4 was used to convert short-chain fatty acyl-ACPs to the corresponding FFAs, which were then converted to SCAs by the sequential reactions of E. coli fatty acyl-CoA synthetase, Clostridium acetobutylicum fatty acyl-CoA reductase and Arabidopsis thaliana fatty aldehyde decarbonylase. The final engineered strain produced up to 580.8 mg l−1 of SCAs consisting of nonane (327.8 mg l−1), dodecane (136.5 mg l−1), tridecane (64.8 mg l−1), 2-methyl-dodecane (42.8 mg l−1) and tetradecane (8.9 mg l−1), together with small amounts of other hydrocarbons. Furthermore, this platform strain could produce short-chain FFAs using a fadD-deleted strain, and short-chain fatty esters by introducing the Acinetobacter sp. ADP1 wax ester synthase (atfA)5 and the E. coli mutant alcohol dehydrogenase (adhEmut)6.

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Myggmedel

Inlägg av Tryggve » tor 03 okt 2013, 13:31

Såg artikel i DN om nytt medel för att hålla myggor borta.

Artikel i DN
http://www.dn.se/nyheter/vetenskap/geno ... myggmedel/

Länk till Natureartiklen med abstract.

Odour receptors and neurons for DEET and new insect repellents
Odour receptors and neurons for DEET and new insect repellents
There are major impediments to finding improved DEET alternatives because the receptors causing olfactory repellency are unknown, and new chemicals require exorbitant costs to determine safety for human use. Here we identify DEET-sensitive neurons in a pit-like structure in the Drosophila melanogaster antenna called the sacculus. They express a highly conserved receptor, Ir40a, and flies in which these neurons are silenced or Ir40a is knocked down lose avoidance to DEET. We used a computational structure–activity screen of >400,000 compounds that identified >100 natural compounds as candidate repellents. We tested several and found that most activate Ir40a+ neurons and are repellents for Drosophila. These compounds are also strong repellents for mosquitoes. The candidates contain chemicals that do not dissolve plastic, are affordable and smell mildly like grapes, with three considered safe in human foods. Our findings pave the way to discover new generations of repellents that will help fight deadly insect-borne diseases worldwide.

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Nobelpris

Inlägg av Tryggve » tis 08 okt 2013, 17:33

Just det, nobelpris i medicin var det ju.

Cell transport carries off Nobel
Cell transport carries off Nobel

Medicine prize goes to discoverers of vesicle system that shuttles biomolecules around cells.

Three scientists who explained the inner workings of a ‘cellular postal service’ shared this year’s Nobel Prize in Physiology or Medicine. Their work pinpointed how cells shuttle proteins and other biomolecules from one location to another — a process that is important in the release of neurotransmitter chemicals, the secretion of insulin and countless other duties.
Själv tycker jag att detta pris var rätt välförtjänt, även om dessa herrar i år inte var bland de mest hett tippade kandidaterna.

EDIT: lite vetenskaplig bakgrund till priset.
http://www.nobelprize.org/nobel_prizes/ ... ze2013.pdf

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Re: Nobelpris

Inlägg av Blafsen » tis 08 okt 2013, 23:19

Tryggve skrev: Själv tycker jag att detta pris var rätt välförtjänt, även om dessa herrar i år inte var bland de mest hett tippade kandidate
Desto mer tippade var fysikpristagarna.

De medicinska verkar vara välförtjänta, men vilka var de mest tippade?

BTW, skönt med såna här trådar efter allt jävla småaktigt tjafs på andra trådar som nästan får en att skämmas för att kalla sig skeptiker. Men bara nästan............än så länge.
......men jag är inte smartare än en femteklassare.

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Re: Nobelpris

Inlägg av Tryggve » ons 09 okt 2013, 09:07

Blafsen skrev: Desto mer tippade var fysikpristagarna.
Så sant. :-)
Blafsen skrev: De medicinska verkar vara välförtjänta, men vilka var de mest tippade?
Lite olika bud. Marc Feldmann och Ravinder Maini trodde väl några. En del menade att priset skulle gå till Aharon Razin, Howard Cedar och Adrian P. Bird för studier om metylering av DNA, och hur det påverkar DNA-expression.

Blafsen skrev: BTW, skönt med såna här trådar efter allt jävla småaktigt tjafs på andra trådar som nästan får en att skämmas för att kalla sig skeptiker. Men bara nästan............än så länge.
Tackar. Jo, jag ledsnade också på tjafstrådarna för länge sedan. Tyvärr verkar de intressera betydligt fler användare än vad andra trådar gör. Men det är väl så det är.

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Bot mot skallighet?

Inlägg av Tryggve » tis 22 okt 2013, 19:21

Jag antar (fördomsfull som jag är) att detta är något som har rapporterats om i dagstidningarna. :smile2:
För ca 40 år sedan så gjorde man tydligen experiment där man odlade follikelceller från möss, och genom att transplantera dessa så kunde man återställa hårväxt på hårlösa djur. Dock så fungerade det inte på människor.
Nu verkar det som om man har fått det att fungera, genom att modifiera odlingsprotokollet.

Cultured follicles offer hope for beating baldness

Cultured follicles offer hope for beating baldness


Old cell-growth method moves hair restoration technique from mice to humans.

Life seemed to be unfair to balding people. More than four decades ago, scientists found a way grow hair follicles in hairless rodents by cultivating skin cells in a dish and implanting them under the skin. But when they tried the same thing in humans, it never worked. Now, a simple tweak to the culturing technique shows that there might be hope for countering baldness.

Follicles develop from dermal papilla cells in the skin. When scientists harvest such cells from mice and culture them in a Petri dish, the cells multiply and form a clump. But the same does not happen for human cells. Geneticist Angela Christiano at Columbia University in New York and her colleague Colin Jahoda, a cell biologist at Durham University, UK, wondered whether the rodent cells' ability to group together was what allowed them to induce follicles successfully.

So the team tried placing the human papilla cells in a hanging-drop culture — a 100-year-old technique in which the cells hang in droplets of a carrier medium underneath the lid of a Petri dish. Gravity causes the cells to cluster together at the bottom of the drop in a more natural, three-dimensional (3D) configuration, rather than spreading out on a flat plane.

“The drop culture allows them to maintain their spatial context and develop an extracellular matrix,” says Christiano. “That seems to allow the cells to recognize that they can induce follicles.”
Just detta var väldigt intressant:
Christiano found that growing cells on a flat surface disrupted the expression of nearly 4,000 genes, whereas the hanging-drop method restored normal function to about 22% of those — enough, it seems, to allow them to induce follicles. Several of the genes restored had been previously associated with hair growth, including an important signalling pathway known as Wnt, which transmits signals from outside the cell to inside. Still, says Christiano, “we were surprised at how few were enough to start induction”.

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Kemisk klocka?

Inlägg av Tryggve » tis 22 okt 2013, 19:29

Data som visar att man möjligen kan använda metylering av DNA för att mäta ålder på vävnad, och identifiera om det finns risk för utveckling av cancer.

Chemical 'clock' tracks ageing more precisely than ever before
Chemical 'clock' tracks ageing more precisely than ever before

DNA methylation could shed light on why some tissues are prone to cancer.

Greying hair and wrinkles are external signs of aging, but they are not very precise. Now research shows that a code written into the body's epigenome — the chemical tags that modify DNA — can accurately tell the age of human tissues and cells. This ‘clock’ could provide insights into why certain tissues age faster than others, and why those tissues may be more cancer-prone.

In the past few years, researchers have been homing in on regions of DNA that accrue lots of chemical tags called methyl groups as people age. Such methylation can selectively switch off genes. “What was not yet known was that one can develop an age predictor that really works well across most tissues and cell types,” says Steve Horvath, a bioinformatician at the University of California, Los Angeles.

n a paper published today in Genome Biology1, Horvath reveals how methylation levels change in human tissues from before birth to the age of 101, and shows that it is a near-perfect predictor of age for non-cancerous tissues. The study “represents the most convincing demonstration so far” of age-associated changes in DNA methylation that are consistent across most tissue types, says Andrew Teschendorff, a computational biologist at University College London.

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Nedslående nyheter om HIV-vaccin

Inlägg av Tryggve » tis 22 okt 2013, 19:45

En artikel som diskuterar resultaten kring test av ett vaccin mot HIV. Resultaten tycks peka på en ökad risk för HIV-infektion för de som har fått vaccinet, men det är oklart varför, och resultaten är omstridda.

HIV vaccine raised infection risk

HIV vaccine raised infection risk


Biological and lifestyle differences cannot fully explain infection spike among trial participants.

Evidence is mounting that an experimental vaccine to protect people against HIV increases the risk of infection, according to results presented on 10 October at the AIDS Vaccine 2013 conference in Barcelona, Spain.

This is not the first report of problems with the vaccine made by pharmaceutical giant Merck, based in Whitehouse Station, New Jersey. In 2007, researchers prematurely cancelled two clinical trials after the vaccine — comprising a vector made from the common-cold virus adenovirus 5 (Ad5) modified to contain HIV genes — proved ineffective at preventing HIV. In the larger of the two trials, called STEP, the vaccine seemed to increase the risk of infection, especially in men. But the risk declined over time and narrowed further when the researchers accounted for factors such as circumcision, sexual activity and previous infection with Ad5.

The second trial, in Phambili, South Africa, was shut down after little more than six months, and its 800 participants were told whether they had received the vaccine or a placebo. When a team led by Glenda Gray, a paediatrician at the University of the Witwatersrand in Johannesburg, South Africa, followed up earlier this year, it found that 119 of those patients had contracted HIV. Overall, people who had received the vaccine were significantly more likely to be infected than those who had received the placebo.

“I spent most of this year trying to find a non-biological reason for these results,” says Gray. But when her team accounted for biological and lifestyle differences in their participants, it found that the vaccine recipients were still significantly more likely to have HIV. In a separate study, biostatistician Peter Gilbert of the Fred Hutchinson Cancer Research Center (FHCRC) in Seattle, Washington, analysed the STEP and Phambili trials together and found that the vaccine seems to raise the risk of infection by 41%.

Gray says the findings are confusing, as the previous explanation for the increase in infection rate observed in the STEP trial had been that the vaccine briefly overstimulated recipients' immune systems, making them more susceptible to HIV.

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Re: Nedslående nyheter om HIV-vaccin

Inlägg av Blafsen » tis 22 okt 2013, 22:29

Tryggve skrev:En artikel som diskuterar resultaten kring test av ett vaccin mot HIV. Resultaten tycks peka på en ökad risk för HIV-infektion för de som har fått vaccinet, men det är oklart varför, och resultaten är omstridda.
Det där får mig osökt att tänka på detta: http://www.aftonbladet.se/senastenytt/t ... 7697091.ab
Tydligen anses smittorisken vid samlag numera vara mycket låg. Professor Jan Albert säger själv att om han eller hans fru hade varit smittad hade de nog ändå haft oskyddat samlag med den kunskap de har idag.
......men jag är inte smartare än en femteklassare.

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Re: Nedslående nyheter om HIV-vaccin

Inlägg av Moridin » tis 22 okt 2013, 23:02

Blafsen skrev:
Tryggve skrev:En artikel som diskuterar resultaten kring test av ett vaccin mot HIV. Resultaten tycks peka på en ökad risk för HIV-infektion för de som har fått vaccinet, men det är oklart varför, och resultaten är omstridda.
Det där får mig osökt att tänka på detta: http://www.aftonbladet.se/senastenytt/t ... 7697091.ab
Tydligen anses smittorisken vid samlag numera vara mycket låg. Professor Jan Albert säger själv att om han eller hans fru hade varit smittad hade de nog ändå haft oskyddat samlag med den kunskap de har idag.
Givetvis fullständig orimligt då icke-detekterbar viral load i blodplasman inte är samma sak som icke-detekterbar viral load i sperman. Det kan finnas upp till 2400 copy number (det räcker med en för att bli infekterad) i sperman trots att nivån är icke-detekterbar i blodplasman.

http://www.ncbi.nlm.nih.gov/pubmed/22382146

Det finns ett annat fel i resonemanget, och det är att man utgår ifrån att genomsnittet säger något som spridningen. Bara för att den genomsnittliga risken är låg i förhållande till andra sexuellt överförbara infektioner betyder inte att det finns grupper där risken är betydligt högre t.ex. människor som har anal sex, har dry sex, har HSV-2 osv.

Tråkigt att professor Jan Albert inte har tillräckligt kunskap om ämnet han uttalar sig om (eller det kanske är mer troligt att journalisten ställt till det). Extremt problematiskt att gå ut med sådana här uttalanden i media. Det riskerar en del av den HIV prevention som seriösa människor arbetat med längre.
Either you believe evidence that can be tested, verified, and repeated will lead to a better understanding of reality, or you do not. - Michael Specter
|AIDSTruth | Evidens för makroevolution | Skeptical Science|

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Re: Nature News

Inlägg av Blafsen » tis 22 okt 2013, 23:27

Här svarar Jan Albert själv på frågor http://www.svt.se/nyheter/vetenskap/hel ... ittorisken

Tydligen är det behandling med bromsmediciner som minskar smittorisken. Dock nämner han att studierna är gjorda på vaginala samlag. När det gäller anala påpekar han att för lite studier finns för att uttala sig säkert.
......men jag är inte smartare än en femteklassare.

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