Health and Medical News and Resources

General interest items edited by Janice Flahiff

[News article] Ciliopathies lie behind many human diseases — ScienceDaily

Ciliopathies lie behind many human diseases — ScienceDaily.

Excerpt

Date:December 1, 2014
Source: American Institute of Biological Sciences
Summary: Growing interest in cilia, which are finger-like organelles that extend from the bodies of individual cells, has revealed their role in a number of human ailments. As a result of cilia’s presence in a wide variety of cells, defects in them cause diverse human diseases that warrant further study.

Cilia perform a broad range of functions, including a starring role in cell signalling. Motile ones wiggle and so move fluids within the body, including cerebrospinal fluid in the brain. In humans, cilia are found on almost every cell in the body. Because of this, ciliopathies often make themselves known as syndromes with widely varying effects on a number of tissue types. For instance, the ciliopathy Jeune asphyxiating thoracic dystrophy involves the development of abnormally short ribs, accompanied by short limbs and, occasionally, the development of extra digits.

In primary ciliary dyskinesia, motile cilia are dysfunctional and fail to beat. This can lead to bronchitis resulting from the failure to clear mucus from the sufferer’s airways. Male patients with primary ciliary dyskinesia are infertile because of impaired motility of the sperm’s flagellum (flagella and cilia are structurally similar).

The article’s authors point to a number of other human diseases in which cilia may play a role; for example, some cancers and neurological diseases may be related to ciliopathies. Because of the limitations placed on research involving humans, the authors propose the use of model species ranging from the green alga Chlamydomonas to the house mouse to further study the role of cilia. They write, “We can anticipate that new and improved techniques will open new avenues for gaining further insight into these immensely important and ever more fascinating cell organelles.”

December 5, 2014 Posted by | Medical and Health Research News | , , , , , , , , | Leave a comment

[Press release]NIH scientists determine how environment contributes to several human diseases

NIH scientists determine how environment contributes to several human diseases.
From the 25 November 2014 NIH Press Release

Using a new imaging technique, National Institutes of Health researchers have found that the biological machinery that builds DNA can insert molecules into the DNA strand that are damaged as a result of environmental exposures. These damaged molecules trigger cell death that produces some human diseases, according to the researchers. The work, appearing online Nov. 17 in the journal Nature, provides a possible explanation for how one type of DNA damage may lead to cancer, diabetes, hypertension, cardiovascular and lung disease, and Alzheimer’s disease.

Time-lapse crystallography was used by National Institute of Environmental Health Sciences (NIEHS) researchers to determine that DNA polymerase, the enzyme responsible for assembling the nucleotides or building blocks of DNA, incorporates nucleotides with a specific kind of damage into the DNA strand. Time-lapse crystallography is a technique that takes snapshots of biochemical reactions occurring in cells.

Samuel Wilson, M.D., senior NIEHS researcher on the team, explained that the damage is caused by oxidative stress, or the generation of free oxygen molecules, in response to environmental factors, such as ultraviolet exposure, diet, and chemical compounds in paints, plastics, and other consumer products. He said scientists suspected that the DNA polymerase was inserting nucleotides that were damaged by carrying an additional oxygen atom.

DNA polymerase

After the DNA polymerase (gray molecule in background) inserts a damaged nucleotide into DNA, the damaged nucleotide is unable to bond with its undamaged partner. As a result, the damaged nucleotide swings freely within the DNA, interfering with the repair function or causing double-strand breaks. These steps may ultimately lead to several human diseases. (Graphic courtesy of Bret Freudenthal)

 

“When one of these oxidized nucleotides is placed into the DNA strand, it can’t pair with the opposing nucleotide as usual, which leaves a gap in the DNA,” Wilson said. “Until this paper, no one had actually seen how the polymerase did it or understood the downstream implications.”

November 28, 2014 Posted by | environmental health, Medical and Health Research News | , , , , , , | Leave a comment

   

%d bloggers like this: