Category: Biology (page 3 of 63)

the problem with cancer cells

HeLa cells cancer research

HeLa cells, cancer cells originally isolated from Henerietta Lacks, are among the most widely used cell lines for scientific research

Cell lines are frequently used in cancer research studies. They are pretty easy to maintain and they grow fast. The cell lines give us insight into some of the cellular pathways involved in tumor biology. They are often used as early-stage screens for potential cancer therapeutics, even though scientists know that they do not exactly share the same biology as an actual tumor. Cancer cells grow rapidly and they generate many mutations in the process. In a few cycles, the cells that you have in culture are different genomically than the cells that you started with. But still, having some information on what cells maybe doing in a tumor is better than no information at all.

Now Derek Lowe calls attention to a new study in Nature, which points out a potential problem with these cell lines in culture. In this new paper, the researchers found that not only are cancer cells different from the tumor that they started from, but there can be many differences within a strains of any given cell line.  When they observed 27 strains of the MCF7 breast cancer line, the discovered rapid genetic diversification. They then looked at 13 additional cell lines and saw similar results. The genetic differences changed activation of gene expression, cell morphology and cell proliferation.

Derek Lowe sums up what this means for compound screening in cancer cell lines:

At least 75% of the compounds that showed strong inhibition of one MCF7 line were totally inactive against others. That’s going to confound experiments big-time, and this paper is a loud warning for people to be aware of this problem and to do something about it.

what is sarin?

What is sarin

Sarin. The deadly gas.

As you’ve probably heard by now, sarin nerve agent was probably behind the death of more than 80 people in Syria last week.  Bashar al-Assad is suspected of using the gas against civilians last week, in what is surely one of the most heinous acts of the ongoing Syrian Civil War. News media showed images of the victims struggling to breathe moving President Donald Trump to engage in a missle strike on Thursday night. The name  sarin is an acronym of the four scientists who created it: Gerhard Schrader, Otto Ambros, Gerhard Ritter, and Hans-Jürgen von der Linde.

But what is sarin, and why is it so deadly?

Sarin is a clear colorless gas, that is  also known as GB. In it’s purest form it has not taste and no odor. The organophosphorus compound is manufactured by humans, and not found in nature. It was first manufactured in the 1930s.

Sarin is deadly becuse it attacks the nervous system preventing proper degradation acetylcholine at neuromuscular junctions. The nerve gas binds to acetylcholinesterase, an enzyme that degrades the acetylcholine, to send signals between nerves and muscles. This means that when someone is exposed to sarin, even at very low levels, their nerve signals don’t communicate properly with muscles. The muscles do not contract or expand as they usually would.  Death after sarin exposure will usually occur as a result suffocation due to the inability to control the muscles involved in breathing. Death usually occurs within 1 to 10 minutes after exposure.

Is there a cure?

There is an antidote for sarin exposure. Atropine treats the physiological symptoms of poisoning, but does not reverse the muscular symptoms. Biperiden is sometimes used as an alternative to atropine due to its better blood–brain barrier penetration and higher efficacy. The drug pralidoxime can regenerate cholinesterase activity, but only if administered within a 5 hour window.

 

yvette fay francis-mcbarnette

The New York Times ran an obituary commemorating the life of Dr. Yvette Francis-McBarnette. I had never heard of her but found her life story inspirational, especially for budding minority scientists.

Yvette Francis McBarnette

Dr Yvette Fay Francis-McBarnette

Yvette immigrated to New York City from Jamaica with her parents and at 14 years old she began studies at Hunter College. After completing a bachelor’s degree in physics, she began a master’s degree in chemistry at Columbia University. Then she went on to be come only the second black woman to earn a medical degree from Yale University.

As a physician, she made tremendous progress in studying and treating sickle cell anemia in young patients. Sickle cell disease deforms the shape of red blood cells, making them rigid and harder to pass through capillaries. It can lead to oxygen deprivation in organs and tissues and also severe pain. The disease is more prevalent in black and Mediterranean populations.Yvette pioneered new antibiotic treatments for the disease and established the Foundation for Research and Education in Sickle Cell Disease. And she did all of this work during the 1950s and 60s when women had fewer opportunities and less support than exists today, doubly so for black women.

 

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