Navigation Links
Tears reveal some of their deepest secrets to researchers

It's no secret why we shed tears. But exactly what our tears are made of has remained a mystery to scientists.

A new study sheds some light on the complex design of tears. What we think of as tears, scientists call tear film, which is made up of three distinct, microscopic layers. The middle, watery layer ?what we normally think of as tears when we cry ?is sandwiched between a layer of mucus and an outer layer of fatty, oily substances collectively called meibum.

It's in this outer layer that researchers describe, for the first time, a new class of lipids ?a type of fat ?that make up part of the film. They also identified one of these lipids, oleamide, which had not been known to be a part of tears before.

With each blink, meibum spreads over the surface of the eye. It keeps the watery middle layer in place, ensuring that our eyes stay moist.

Finding these lipids may help scientists better understand the causes of eye-related disorders such as dry eye disease, which affects anywhere from 12 to 14 million Americans, said Kelly Nichols, the study's lead author and an assistant professor of optometry at Ohio State University.

"The lack of certain compounds in the tear film may result in a number of different eye-related disorders, including dry eye," she said. "The amount of oleamide and related lipids in tear film may be related to these disorders."

Dry eye is really a collection of irritating symptoms that includes microscopic damage to the front of the eye. The eyes may ache, burn, feel extremely dry or excessively tear.

The researchers report their findings in the current issue of the journal Investigative Ophthalmology and Visual Science.

They collected oily meibum secretions from the meibomian glands of healthy volunteers. The meibomian glands are tiny, grape-like clusters of cells that line the rim of our upper and lower eyelids ?the outlets to these glands are roughly adjacent to the e yelashes. Researchers gently pressed the volunteers' lower eyelids and collected droplets of meibum in tiny glass tubes.

The researchers examined the meibum samples in the laboratory. They used a technique called electrospray mass spectrometry to differentiate between the different lipid components. This technique adds an electric charge to microscopic droplets of the oily substance, which allows the instrument to detect different components based on electrical charges and mass.

Nichols points out that researchers have used other techniques, such as chromatography, to characterize types of lipids in the tear film, but advances in mass spectrometry technology are improving research efforts.

"Other scientists used different techniques to try to determine the composition of meibum, but mass spectrometry is sensitive enough to detect individual lipid molecules, like oleamide," Nichols said.

Oleamide was first identified as a lipid in the brain, where one of its roles is to induce sleep. It also has other key functions throughout the central nervous system. But the current study is the first to find and describe oleamide and related lipids in tear film.

"The finding could give us more insight into the role of lipid activity in humans and may also indicate a new function for oleamide and related lipids in cellular signaling in the eye and in the maintenance of tear film," said Nichols, adding that researchers don't fully understand the function of oleamide, or the other lipids in the meibum.

"Oleamide appears to be a predominate lipid in tear film," she said. "It's there for a reason, but we're not sure yet what that reason is."

Nichols and her team are currently studying the role of oleamide in cellular signaling and communication in the eye, along with the role that the lipid may play in dry eye.

"Dry eye is really a disorder of symptoms that irritate the eyes," Nichols said. "Not everyone w ith dry eye responds to the same treatment. If we could find individuals with varying oleamide levels, then we may be able discern one cause of dry eye, and specifically treat that.

"Even though two people with dry eye may have the same symptoms, there may be very different causes underlying those symptoms."

Source:Ohio State University

Related biology news :

1. Elusive HIV shape change revealed; Key clue to how virus infects cells
2. Timing is everything: First step in protein building revealed
3. Researchers reveal the infectious impact of salmon farms on wild salmon
4. A bacterial genome reveals new targets to combat infectious disease
5. Scientists reveal molecular secrets of the malaria parasite
6. Studies reveal methods viruses use to sidestep immune system
7. First real-time view of developing neurons reveals surprises, say Stanford researchers
8. Examination of internal wiring of yeast, worm, and fly reveals conserved circuits
9. Family trees of ancient bacteria reveal evolutionary moves
10. NYU study reveals how brains immune system fights viral encephalitis
11. Iron exporter revealed that may explain common human disorder

Post Your Comments:

(Date:10/29/2015)...  Connected health pioneer, Joseph C. Kvedar , ... health and wellness, and the business opportunities that arise ... Internet of Healthy Things . Long before health ... Dr. Kvedar, vice president, Connected Health, Partners HealthCare, was ... care from the hospital or doctor,s office into the ...
(Date:10/29/2015)... , Oct. 29, 2015 Today, ... announced a partnership with 2XU, a global leader ... deliver a smart hat with advanced bio-sensing technology. ... other athletes to monitor key biometrics to improve ... strategic partnership, the two companies will bring together the ...
(Date:10/27/2015)... , October 27, 2015 ... Automated Semantic Gaze Mapping technology (ASGM) automatically maps data ... Eye Tracking Glasses , so that they can ... --> Munich, Germany , October ... automatically maps data from mobile eye tracking videos created ...
Breaking Biology News(10 mins):
(Date:11/25/2015)... 25, 2015 The Global ... a professional and in-depth study on the current ... (Logo: ) , The ... including definitions, classifications, applications and industry chain structure. ... international markets including development trends, competitive landscape analysis, ...
(Date:11/24/2015)... , Nov. 24, 2015 Cepheid (NASDAQ: ... speaking at the following conference, and invited investors to ... NY      Tuesday, December 1, 2015 at 11.00 ... NY      Tuesday, December 1, 2015 at 11.00 ... Conference, New York, NY      Tuesday, ...
(Date:11/24/2015)... Tampa, Florida (PRWEB) , ... November 24, 2015 ... ... its biggest event of the year and one of the premier annual events ... USA, and ran from 8–11 November 2015, where ISPE hosted the largest number ...
(Date:11/24/2015)... ... ... This fall, global software solutions leader SAP and AdVenture Capital brought together dozens ... BIG ideas to improve health and wellness in their schools. , Now, the top ... of SAP's Teen Innovator, an all-expenses paid trip to Super Bowl 50, and an ...
Breaking Biology Technology: