Scientists from Columbia University are reporting that osteoporosis, a chronic bone-wasting condition that affects 10 million elderly Americans, may be mediated by serotonin, a compound previously known for its role in brain functioning.

The astonishing conclusion appears in the journal Cell.

Scientists had known for years that a rare, inherited brittle bone disease was caused by a mutation of a gene known as LRP5. More recently, a second mutation of LRP5 was reported to cause just the opposite—bones so dense that tooth extractions became nearly impossible.

So something was up with LRP5, and the tempting assumption was that the gene directly impacted bone formation.

Not so, according to Gerard Karsenty and colleagues. They proved that LRP5 blocks production of serotonin in the gut.

Then they proved that while gut serotonin has no impact on brain functioning, it does impair bone formation after travelling there through the blood stream.

“We made mice with the inactivated gene,” Dr. Karsenty told the New York Times. These mice had 4 times the normal levels of circulating gut serotonin, and in their bodies “the bone-forming cells are on strike,” he added.

The mice developed marked osteoporosis.

Karsenty’s team then harvested bone cells from the brittle boned mice and proved in the laboratory that the cells were perfectly capable of normal development and functioning, so long as they were not bathed in serotonin.

Karsenty’s team hopes its work might prompt development of a drug that suppresses gut serotonin synthesis and thus stimulate bone growth in osteoporosis patients.

Facebook has decided it will not allow employees to sell shares in the privately held company after all. At least not now.

“After carefully considering the current environment, we’ve decided to establish an open-ended timetable for an employee stock sale program,” company officials told the Wall Street Journal.

Facebook CEO Mark Zuckerberg had announced the unusual plan in August. It would have permitted employees to sell $900,000 worth of their vested shares at a $4 billion valuation according to the Journal.

The program had been trumpeted as a revolutionary way for a company to reward employees without sacrificing its exit strategy.

But Facebook encountered unexpected trouble lining up investors to fund the plan at the $4 billion valuation.

In 2007, Microsoft acquired 1.6% of Facebook for $240 million, thus valuing the company at $15 billion but that deal was for preferred stock and included an ad sharing arrangement. Now many are questioning Facebook’s revenue model and the Great Economic Crisis of 2008 hasn’t helped, either.

Which left it up to Zook to submit this Debbie-downer of an email, “I’m writing this note to let you know some bad news. Despite a lot of work, we have not been able to finalize a plan for the employee stock sale we announced in August.”

That had to hurt, since the company has stated recently that it does not plan an IPO anytime soon.  Of course, Facebook’s 800 employees are still drawing paychecks, and these days that’s not half bad.

Toiling for hours in basement offices can make radiologists a bit grumpy, but scientists have found a simple way to cheer them up and produce more thorough reports at the same time.

Yahonatan N. Turner and colleagues at Shaare Zedek Medical Center in Jerusalem reported that adding patient photos to their x-ray files increased radiologist’s empathy and generated longer reports, more incidental findings, more summaries and more suggestions for follow-up study.

In their experiment, the scientists divided patients into a face first group, a face later group and a control group.

In the first group, radiologists viewed a patient’s head-shot before interpreting the patient’s CT scan. In the second, radiologists reviewed a CT without seeing a photo, and reviewed the scan again 3 months later, this time preceded by a photo. CT interpretations in control group were rendered sans photo.

In accompanying questionnaires, radiologists strongly agreed that the photos motivated them to empathize with the patient and “feel more like a physician,” according to MedPageToday.

The majority of respondents supported routine additions of patient photos to x-ray files.

But before everyone heads off to CT with happy snaps on thumb-drives, the scientists warn that photos could introduce bias beyond what radiologists might glean from the patient’s name, age, gender, present illness and past history.

And HIPAA rules would require that patients consent to having their photos passed around.