WEDNESDAY, Feb. 13 (HealthDay News) -- Eye drops containing alpha-linolenic acid (ALA) significantly reduced symptoms of dry eye syndrome in mice, a new study says.

ALA is an omega-3 fatty acid that's not made by the body and has to be obtained through diet. Dry eye, which affects about 10 million people in the United States, causes symptoms such as stinging, burning, irritation or a feeling of scratchiness. It can lead to problems with day-to-day activities such as driving and reading.

Currently, treatment options are limited in terms of effectiveness and undesirable side effects, according to background information in the study, published in the February issue of the journal Archives of Ophthalmology.

Dr. Reza Dana, a Harvard Medical School professor and Cornea Service Director at the Massachusetts Eye and Ear Infirmary, and colleagues at the Schepens Eye Research Institute tested three formulations of fatty acids: 0.2 percent ALA; 0.2 percent linoleic acid (an omega-6 fatty acid); and 0.01 percent ALA combined with 0.1 percent linoleic acid.

Some mice received once-a-day treatment with these eye drops, while other mice did not receive any eye drops. The eyes of mice treated with ALA showed a significant reversal in epithelial damage to the cornea, which is the transparent dome that covers the pupil.

"The current study for the first time demonstrates the benefit of topical application of a particular fatty acid in treating the signs of dry eye syndrome at both the molecular and cellular levels," Dana noted.

"Using topical formulations of fatty acids to treat dry eye would allow for more flexibility for treatment, including lessening side effects that patients can experience from oral intake of fatty acids. Clinical studies with topical fatty acids are being planned, which, if successful, could alter the method by which this common condition is treated," Dana said.

The study received funding from Johnson & Johnson Vision Care Inc.

More information

The U.S. National Library of Medicine has more about dry eye syndrome.

WEDNESDAY, Feb. 13 (HealthDay News) -- Multiple sclerosis patients who smoke marijuana in search of symptom relief are more likely to suffer cognitive shortfalls and mood disorders, new Canadian research suggests.

A slowing down in the ability to process and remember information is one significant side effect, as is a rise in the rate of depression and anxiety.

"This is a small study, so our findings are preliminary, but the bottom line is that multiple sclerosis patients who smoke cannabis appear to be at an increased risk for cognitive issues, particularly with respect to the speed of their thinking," said study author Dr. Anthony Feinstein, a professor of psychiatry with the Sunnybrook Health Sciences Centre's department of psychiatry at the University of Toronto.

Feinstein's observations are published in the Feb. 13 online edition of Neurology and are focused exclusively on the impact of smoking marijuana illegally obtained by patients themselves. Medically prescribed marijuana was not studied.

The authors noted that a "significant minority" of multiple sclerosis patients smoke marijuana to combat the tingling, numbness, blindness and paralysis that can accompany the progressive and often disabling nervous system disease.

However, Feinstein's team stressed that scientists have yet to definitively prove that the psychoactive substance -- long linked to psychosis, anxiety and delirium among healthy users -- provides a measurable benefit to the more than 400,000 Americans and 2.5 million people worldwide who suffer from the disease.

The researchers therefore assessed the experience of 140 Toronto-based MS outpatients, 10 of whom had smoked the drug at least once in the previous month and were considered regular marijuana users.

All the patients -- three-quarters of them women -- underwent cognitive and mental health exams by a neurologist and a neuro-psychiatrist. Interviews were also conducted to assess disease severity and course, medications being used, and current disability.

Feinstein and his team observed that while pot smokers were younger, there were no differences between marijuana users and nonusers in terms of gender, education, or MS disease course or duration.

However, MS patients who used marijuana were found to perform 50 percent slower on tests tracking information-processing speed and were more likely than nonusers to have a mental disability of some kind.

Marijuana use was also associated with a greater risk for being depressed or experiencing anxiety. However, the authors were not able to determine whether the drug had triggered such conditions, or if patients had sought out marijuana to help deal with a preexisting emotional issue.

They nonetheless cautioned that smoking marijuana might further raise the risk for experiencing the kind of neuro-psychological impairment that typically occurs among 40 percent to 65 percent of all MS patients.

Feinstein said that he next hopes to gather a much larger pool of patients, while exploring possible differences in the health impact of street-purchased marijuana versus prescribed cannabis.

Meanwhile, Dr. Marshall Keilson, director of neurology at Maimonides Medical Center in Brooklyn, N.Y., said he thinks it best to proceed on a case-by-case basis.

"There are some MS patients who are emotionally disabled from their disease, and if we can use cannabis to help them feel better about the world or life, we should," he said. "We need to always err on the side of doing what's best for our patients. And I don't necessarily believe there is a permanent damage to the brain, based on occasional marijuana use. If they're smoking 10 times a day, yes, there will be damage done. But this goes for excessive alcohol use, too. So, I think we're going to end up somewhere in the middle with this."

More information

For more on multiple sclerosis, visit the National Multiple Sclerosis Society.

TUESDAY, Feb. 12 (HealthDay News) -- It may be possible to develop a vaccine to control noroviruses -- a common cause of stomach flu -- but it's likely a such a vaccine would have to be changed every year because the viruses evolve quickly to avoid attacks by the immune system, new research suggests.

Noroviruses infect cells after attaching to histo-blood group antigens (HBGA), molecules located on the surface of cells. HBGAs are a family of complex sugar molecules that exist in great variety among humans, according to background information in the study in the journal PLoS Medicine.

Ralph Baric, of the University of North Carolina at Chapel Hill, and his colleagues found this large variety of HBGAs contributes to recurrence of norovirus outbreaks, even among people who have previously been exposed to the virus and have developed antibodies against it.

The researchers analyzed noroviruses that caused several outbreaks and found that the viruses evolved to avoid attack by immune system antibodies.

Over time, some of the norovirus strains developed a shape that enabled them to bind other forms of HBGA. These viruses were then resistant to previously existing antibodies and able to infect cells carrying that particular form of HBGA. These viruses could then cause a new outbreak, with the cycle repeating itself, the researchers said.

Noroviruses, which can cause nausea, vomiting and diarrhea, are highly contagious. Most people recover within a few days, but the viruses can cause severe problems in very young and in old people. There is no specific treatment for norovirus infection.

More information

The U.S. Centers for Disease Control and Prevention has more about noroviruses.

MONDAY, Feb. 11 (HealthDay News) -- U.S. scientists say they've reprogrammed human skin cells into ones with the same blank-slate properties as embryonic stem cells, a breakthrough that could aid in treating many diseases while sidestepping controversy.

Human embryonic stem cells have the ability to become every cell type found in the human body. Being able to create these cells en masse and without using human eggs or embryos could generate a potentially limitless source of immune-compatible cells for tissue engineering and transplantation medicine, said the scientists, from the University of California, Los Angeles.

The researchers genetically altered human skin cells using four regulator genes, according to findings published online in the Feb. 11 edition of the journal Proceedings of the National Academy of the Sciences.

The result produced cells called induced pluripotent stem cells, or iPS cells, that are almost identical to human embryonic stem cells in function and biological structure. The reprogrammed cells also expressed the same genes and could be coaxed into giving rise to the same cell types as human embryonic stem cells, the researchers said.

"Our reprogrammed human skin cells were virtually indistinguishable from human embryonic stem cells," lead author Kathrin Plath, an assistant professor of biological chemistry and a researcher with the Eli and Edythe Broad Center of Regenerative Medicine and Stem Cell Research, said in a prepared statement. "Our findings are an important step towards manipulating differentiated human cells to generate an unlimited supply of patient specific pluripotent stem cells. We are very excited about the potential implications."

The UCLA findings confirm similar work first reported in late November by researcher Shinya Yamanaka at Kyoto University and James Thompson at the University of Wisconsin. Together, the studies demonstrate that human iPS cells can be easily created by different laboratories and are likely to mark a milestone in stem cell-based regenerative medicine, Plath said.

Reprogramming adult stem cells into embryonic stem cells has significant implications for disease treatment. A patient's skin cells, for example, could be reprogrammed into embryonic stem cells that could be prodded into becoming beta islet cells to treat diabetes, hematopoetic cells to create a new blood supply for a leukemia patient, or motor neuron cells to treat Parkinson's disease, the researchers said.

These new techniques to develop stem cells could potentially replace a controversial method to reprogram cells called somatic cell nuclear transfer (SCNT), sometimes referred to as therapeutic cloning. To date, therapeutic cloning has not been successful in humans.

"Reprogramming normal human cells into cells with identical properties to those in embryonic stem cells without SCNT may have important therapeutic ramifications and provide us with another valuable method to develop human stem cell lines," study first author William Lowry, an assistant professor of molecular, cell and developmental biology, said in a prepared statement. "It is important to remember that our research does not eliminate the need for embryo-based human embryonic stem cell research, but rather provides another avenue of worthwhile investigation."

However, top stem cell scientists worldwide stress further research comparing reprogrammed cells with stem cells derived from embryos -- considered the gold standard -- is necessary.

More information

The U.S. National Institutes of Health has more about stem cells.