Tag Archives: brown university

Physical Properties Predict Stem Cell Outcome

By Guest PostMay 26, 2012Scienceatomic force microscope, bone, bone tissue, brown university, cartilage, eric darling, mesenchymal stem cells, rafael gonzaelz cruz, stiffness, tissue engineer, vera fonseca, viscosity

Tissue engineers can use mesenchymal stem cells derived from fat to make cartilage, bone, or more fat. The best cells to use are ones that are already likely to become the desired tissue. Brown University researchers have discovered that the mechanical properties of the stem cells can foretell what they will become, leading to a potential method of concentrating them for use in healing.

PROVIDENCE, R.I. [Brown University] — To become better healers, tissue engineers need a timely and reliable way to obtain enough raw materials: cells that either already are or can become the tissue they need to build. In a new study, Brown University biomedical engineers show that the stiffness, viscosity, and other mechanical properties of adult stem cells derived from fat, such as liposuction waste, can predict whether they will turn into bone, cartilage, or fat.

That insight could lead to a filter capable of extracting the needed cells from a larger and more diverse tissue sample, said Eric Darling, senior author of the paper published in Proceedings of the National Academy of Sciences. Imagine a surgeon using such a filter to first extract fat from a patient with a bone injury and then to inject a high concentration of bone-making stem cells into the wound site during the same operation. (more…)

Pollination with Precision: How Flowers Do It

By Guest PostMay 23, 2012Naturearabidopsis plants, brown university, chaotic frenzy, female gametes, fertilization, gamete fusion, hap2, kristin beale, logistical efficiency, mark johnson, mechanism, microscope, model, mothers day, mutant sperm, ovule, pollen grains, pollen tubes, pollination, polytubey, precision, reproduction, sex cells, sperm

Pollination could be a chaotic disaster. With hundreds of pollen grains growing long tubes to ovules to deliver their sperm to female gametes, how can a flower ensure that exactly two fertile sperm reach every ovule? In a new study, Brown University biologists report the discovery of how plants optimize the distribution of pollen for successful reproduction.

PROVIDENCE, R.I. [Brown University] — Next Mother’s Day, say it with an evolved model of logistical efficiency — a flower. A new discovery about how nature’s icons of romance manage the distribution of sperm among female gametes with industrial precision helps explain why the delicate beauties have reproduced prolifically enough to dominate the earth.

In pollination, hundreds of sperm-carrying pollen grains stick to the stigma suspended in the middle of a flower and quickly grow a tube down a long shaft called a style toward clusters of ovules, which hold two female sex cells. This could be a chaotic frenzy, but for the plant to succeed, exactly two fertile sperm should reach the two cells in each ovule — no more, no less. No ovule should be left out, either because too many tubes have gone elsewhere, or because the delivered sperm don’t work. (more…)

Clergy can fight HIV on faith-friendly terms

By Guest PostMay 20, 2012Culture, Healthafrican american, african american clergy, aids epidemic, amy nunn, black americans, black clergy, blacks, brown university, hiv, hiv infection, hiv prevention, michelle lally, miriam hospital, philadelphia, sex, sexuality, tim flanigan, united states

In the United States, where blacks bear a disproportionate burden of the HIV/AIDS epidemic, black religious institutions could help turn the tide. In a new study in PLoS ONE based on dozens of interviews and focus groups with 38 of Philadelphia’s most influential black clergy, physicians and public health researchers find that traditional barriers to preaching about HIV prevention could give way to faith-friendly messages about getting tested and staying on treatment.

PROVIDENCE, R.I. [Brown University] — The public health community has long struggled with how best to reduce HIV infection rates among black Americans, which is seven times that of whites. In a new paper in the journal PLoS ONE, a team of physicians and public health researchers report that African-American clergy say they are ready to join the fight against the disease by focusing on HIV testing, treatment, and social justice, a strategy that is compatible with religious teaching. (more…)

Brian Reggiannini Figures out Who’s Talking

By Guest PostMay 19, 2012Sciencealgorithms, analog devices, brian reggiannini, brown university, commercial success, computer, conventional wisdom, david orenstein, harvey silverman, industry, microphone, microphone arrays, modeling talkers, norwood, speaker, speaker recognition, who is talking

If computers could become ‘smart’ enough to recognize who is talking, that could allow them to produce real-time transcripts of meetings, courtroom proceedings, debates, and other important events. In the dissertation that will allow him to receive his Ph.D. at Commencement this year, Brian Reggiannini found a way to advance the state of the art for voice- and speaker-recognition.

Everyone does signal processing every day, even if we don’t call it that. With friends at a sports bar, we peer up at the TV to see the score, we turn our head toward the crashing sound when a waitress drops a glass, and perhaps most remarkably, we can track the fast-paced banter of all the people in our booth, even if we’ve never met some of the friends-of-friends who have insinuated themselves into the scene.

Very few of us, however, could ever get a computer to do anything like that. That’s why doing it well has earned Brian Reggiannini a Ph.D. at Brown and a career in the industry.

In his dissertation, Reggiannini managed to raise the bar for how well a computer connected to a roomful of microphones can keep track of who among a small group of speakers is talking. Further refined and combined with speech recognition, such a system could lead to instantaneous transcriptions of meetings, courtroom proceedings, or debates among, say, several rude political candidates who are prone to interrupt. It could help the deaf follow conversations in real-time. (more…)

Five-Limbed Brittle Stars Move Bilaterally, Like People

By Guest PostMay 14, 2012Natureanimals, belize, bilateral symmetry, bilaterally symmetrical, brain, brittle stars, brown university, bushnell foundation, david orenstein, direction, five limbed, henry astley, humans, locomotion, mark bertness, move bilaterally, ophiocoma echinata, pentaradially symmetrical, radial symmetrical

Brittle stars and people have something in common: They move in fundamentally similar ways. Though not bilaterally symmetrical like humans and many other animals, brittle stars have come up with a mechanism to choose any of its five limbs to direct its movement on the seabed. It’s as if each arm can be the creature’s front, capable of locomotion and charting direction. Results appear in the Journal of Experimental Biology.

PROVIDENCE, R.I. [Brown University] — It appears that the brittle star, the humble, five-limbed dragnet of the seabed, moves very similarly to us.

In a series of first-time experiments, Brown University evolutionary biologist Henry Astley discovered that brittle stars, despite having no brain, move in a very coordinated fashion, choosing a central arm to chart direction and then designating other limbs to propel it along. Yet when the brittle star wants to change direction, it designates a new front, meaning that it chooses a new center arm and two other limbs to move. Brittle stars have come up with a mechanism to choose any of its five limbs to be central control, each capable of determining direction or pitching in to help it move. (more…)

Locked RNA Editing Yields Odd Fly Behavior

By Guest PostApril 26, 2012Scienceabiotic factor, als, arthur sugden, asli sahin, brown university, cell, charles lawrence, dadar, enzyme adar, epilepsy, factor, fruit fly, function, genetic, jacquelyn dorsky, james jepson, lauren alpert, locking down, lou gehrigs disease, nucleus, organism, phenomenon, protein, rna, robert reenan, suicidal depression, temperature, wallflowers, yiannis savva

At the level of proteins, organisms can adapt by editing their RNA — and an editor can even edit itself. Brown University scientists working with fruit flies found that “locking down” the self-editing process at two extremes created some strange behaviors. They also found that the process is significantly affected by temperature.

PROVIDENCE, R.I. [Brown University] — Because a function of RNA is to be translated as the genetic instructions for the protein-making machinery of cells, RNA editing is the body’s way of fine-tuning the proteins it produces, allowing us to adapt. The enzyme ADAR, which does this editing job in the nervous system of creatures ranging from mice to men, even edits itself. In a new study that examined the self-editing process and locked it down at two extremes in fruit flies, Brown University scientists found some surprising insights into how this “fine-tuning of the fine-tuner” happens, including bizarre behavioral effects that come about when the self-editor can’t edit. (more…)

Distinct Brain Cells Recognize Novel Sights

By Guest PostApril 16, 2012Sciencebrain area, brain cell, brown university, cell type, david orenstein, david sheinberg, excitatory neuron, inferior temporal cortex, itc, luke woloszyn, novel sight, plasticity, repair circuit, skull, traumatic brain injury

The brain’s ability to learn to recognize objects plays out in the inferior temporal cortex. A new study offers a possible explanation of how two classes of neurons play distinct roles to help that happen.

PROVIDENCE, R.I. [Brown University] — No matter what novel objects we come to behold, our brains effortlessly take us from an initial “What’s that?” to “Oh, that old thing” after a few casual encounters. In research that helps shed light on the malleability of this recognition process, Brown University neuroscientists have teased apart the potentially different roles that two distinct cell types may play.

In a study published online in advance in the journal Neuron, the researchers document that this kind of learning is based in the inferior temporal cortex (ITC), a brain area buried deep in the skull. Scientists already knew the area was important for visual recognition of familiar items, but they hadn’t figured out the steps required to move from novelty to familiarity, a process they refer to as “plasticity.” (more…)

Bats Save Energy By Drawing in Wings on Upstroke

By Guest PostApril 13, 2012Nature, Scienceaerodynamics, attila bergou, bat wings, bats, brown university, calculation, calculus rich model, daniel riskin, david orenstein, flying machine, inertial energy, muscular wings, physicisist, sharon swartz, wing mass

Bat wings are like hands: meaty, bony and full of joints. A new Brown University study finds that bats take advantage of their flexibility by folding in their wings on the upstroke to save inertial energy. The research suggests that engineers looking at flapping flight should account for wing mass and consider a folding design.

PROVIDENCE, R.I. [Brown University] — Whether people are building a flying machine or nature is evolving one, there is pressure to optimize efficiency. A new analysis by biologists, physicists, and engineers at Brown University reveals the subtle but important degree to which that pressure has literally shaped the flapping wings of bats.

The team’s observations and calculations show that by flexing their wings inward to their bodies on the upstroke, bats use only 65 percent of the inertial energy they would expend if they kept their wings fully outstretched. Unlike insects, bats have heavy, muscular wings with hand-like bendable joints. The study suggests that they use their flexibility to compensate for that mass. (more…)