Dendritic cells and T cells

Dendritic cells trigger an adaptive immune response by activating two major classes of T lymphocytes—cytotoxic T cells that can kill infected host cells, and helper T cells that direct the activities of other immune cells. Cytotoxic T cells recognize class I MHC receptors loaded with antigen, whereas helper T cells recognize class II MHC-peptide. Dendritic cells constitutively express high levels of both class I and class II MCH molecules, making them the most potent activators of T cells, capable of stimulating even “naive” T cells that have never encountered antigen.

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Image: A human lymphocyte (pink pseudocolor) scans the surface of a dendritic cell (blue pseudo-color). The image was obtained using a field emission scanning electron microscope. Scale bar 1µm.

Cell – cell_picture_show-immunology.

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Scientists Work To Unravel Mystery Behind Woman Who Doesn’t Grow

Twenty year old Brooke Greenberg hasn’t grown since age five. For the last 15 years mystified doctors have been unable to explain the cause for Brooke’s disorder that has kept her aging in check. At age twenty, she maintains the physical and mental appearance of a toddler.

Eric Shadt wants to solve this most bizarre of medical mysteries. Director of the Icahn Institute for Genomics and Multiscale Biology at the Mount Sinai Medical Center in New York, Shadt is leading research to uncover the genetic cause for Brooke’s condition.

Because hormones control many of the maturation processes, one of the first things the research team looked at was to see if Brooke’s own hormone levels might be abnormal. In a piece he wrote on Katie Couric’s website on whose show he and the Greenberg family recently appeared, Shadt explained that Brooke “has no apparent abnormalities in her endocrine system, no gross chromosomal abnormalities, or any of the other disruptions known to occur in humans that can cause developmental issues.”

The researchers are now are painstakingly analyzing Brooke’s entire genome in search of unique mutations. Needless to say, it is a formidable undertaking. “Cracking the code on Brooke’s condition,” Shadt wrote, “is the proverbial searching for a needle in a haystack, since likely there is one or a small number of letters changed in Brooke’s genome that has caused her condition.”

via Scientists Work To Unravel Mystery Behind Woman Who Doesn’t Grow | Singularity Hub.

The Beauty of Smooth Muscle

We humans have long wondered how, exactly, we develop from embryos into adults. This photo of an embryonic smooth muscle cell hints at the tremendous complexity of this fundamental biological mystery. And for those of you who might be wondering just what smooth muscles are, they’re the involuntary muscles found in places like the walls of our blood vessels, the digestive tract, the bladder, and the respiratory system.

This exquisite photo was produced using laser scanning confocal microscopy — a precise imaging method that includes the dimension of depth for scientific analysis. Here, green is used to label thin filaments of the protein actin, which is a key component of the cell’s cytoskeleton, and blue indicates another protein, called vinculin, which is enriched in locations involved in cell-cell adhesion.

microscopic image of a cell.

Credit: Vira V. Artym, National Institute of Dental and Craniofacial Research, NIH

via The Beauty of Smooth Muscle | NIH Director’s Blog.

Leprosy bug turns adult cells into stem cells

Leprosy bacteria can reprogram cells to revert to a stem-cell-like state, able to mature into different cell types, researchers report today in Cell1.

The scientists stumbled on the discovery while researching the way leprosy spreads around the body. The mechanism of the hijacking is unclear, but reproducing it could lead to new stem-cell-based therapeutic strategies.

Mouse nervous-system cells (green), hijacked and turned by leprosy bacteria into stem cells, attack muscle fibre (red).

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via Leprosy bug turns adult cells into stem cells : Nature News & Comment.

Aspirin, the 2,000-Year-Old Wonder Drug

Developed in 1897 by the German chemist Felix Hoffmann, aspirin, or acetylsalicylic acid, has long proved its value as an analgesic. Two millenniums before that, Hippocrates, the father of modern medicine, used its active ingredient — which he extracted from the bark and leaves of the willow tree — to help alleviate pain and fevers.

Since then, we’ve gained insight into both the biological mechanism and the effects of this chemical compound. Many high-quality research studies have confirmed that the use of aspirin substantially reduces the risk of cardiovascular disease. Indeed, the evidence for this is so abundant and clear that, in 2009, the United States Preventive Services Task Force strongly recommended that men ages 45 to 79, and women ages 55 to 79, take a low-dose aspirin pill daily, with the exception for those who are already at higher risk for gastrointestinal bleeding or who have certain other health issues. (As an anticoagulant, aspirin can increase the risk of bleeding — a serious and potentially deadly issue for some people.)

via Aspirin, the 2,000-Year-Old Wonder Drug – NYTimes.com.

Drug Stimulates Regeneration of Sound-Sensing Hair Cells and Partial Recovery of Hearing in Deaf Mice

Listen up, live music fans. The hearing loss caused by exposure to loud noise can be at least partially reversed with drugs, according to a study published by U.S. and Japanese researchers last week in the journal Neuron.

The work is the first proof that a drug can spur regeneration of the mammalian ear’s sound-detecting hair cells, which can be damaged by noise exposure. While the hair cells of some animals, such as birds, can regenerate on their own, the hair cells of humans and other mammals cannot. The cells may be damaged by infection or as a side effect of certain drugs as well as after exposure to loud noises.

Sound sensors: The delicate sound-detecting cells in the inner ear can be damaged and die after exposure to loud noises or toxic compounds (top), but they can be regenerated with a drug (bottom).

via Drug Stimulates Regeneration of Sound-Sensing Hair Cells and Partial Recovery of Hearing in Deaf Mice | MIT Technology Review.

Regulating Single Protein Prompts Fibroblasts to Become Neurons

Repression of a single protein in ordinary fibroblasts is sufficient to directly convert the cells – abundantly found in connective tissues – into functional neurons. The findings, which could have far-reaching implications for the development of new treatments for neurodegenerative diseases like Huntington’s, Parkinson’s and Alzheimer’s, will be published online in advance of the January 17 issue of the journal Cell.

<p>Confocal micrograph of a primary human fibroblast cell grown in culture stained blue for actin, a highly abundant protein that makes up the cytoskeleton of cells. Energy-producing mitochondria are shown in green. Image courtesy of Matthew Daniels, University of Oxford and Wellcome Images.</p>
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