What is it about toothpaste that transforms the sweet flavor of orange juice into something so bitter? For the solution to that mysterious sensory phenomenon – in colorful, animated detail – check the latest episode of the American Chemical Society’s award-winning Bytesize Science video series at http://www.bytesizescience.com/ (Video also below)
The video, from the world’s largest scientific society, explains that the mainstay ingredients in toothpaste include a detergent called sodium lauryl sulfate, or SLS for short. When you brush your teeth, SLS produces the foamy suds and gives toothpaste its distinct mouth-feel. SLS also influences the way your personal, powerful chemical sensor tastes food.
That sensor is your mouth, with its 10,000 individual taste buds. Each consists of scores of receptor cells that respond to the basic tastes. Those are sweet, sour, bitter, salty and umami (a pleasant, brothy or meaty flavor). Nerves carry the resulting signals to the brain, which registers tastes. How does SLS affect your sense of taste? For the answer:
Clues To Tooth Regeneration Provided By Alligator Stem Cell Study
From: Medical News Today
For the first time, a global team of researchers led by USC pathology Professor Cheng-Ming Chuong, M.D., Ph.D., has uncovered unique cellular and molecular mechanisms behind tooth renewal in American alligators. Their study, titled “Specialized stem cell niche enables repetitive renewal of alligator teeth,” appears in Proceedings of the National Academy of Sciences, the official journal of the United States National Academy of Sciences.
“Humans naturally only have two sets of teeth – baby teeth and adult teeth,” said Chuong. “Ultimately, we want to identify stem cells that can be used as a resource to stimulate tooth renewal in adult humans who have lost teeth. But, to do that, we must first understand how they renew in other animals and why they stop in people.”
Whereas most vertebrates can replace teeth throughout their lives, human teeth are naturally replaced only once, despite the lingering presence of a band of epithelial tissue called the dental lamina, which is crucial to tooth development. Because alligators have well-organized teeth with similar form and structure as mammalian teeth and are capable of lifelong tooth renewal, the authors reasoned that they might serve as models for mammalian tooth replacement.
“Alligator teeth are implanted in sockets of the dental bone, like human teeth,” said Ping Wu, Ph.D., assistant professor of pathology at the Keck School of Medicine and first author of the study. “They have 80 teeth, each of which can be replaced up to 50 times over their lifetime, making them the ideal model for comparison to human teeth.”
Using microscopic imaging techniques, the researchers found that each alligator tooth is a complex unit of three components – a functional tooth, a replacement tooth, and the dental lamina – in different developmental stages. The tooth units are structured to enable a smooth transition from dislodgement of the functional, mature tooth to replacement with the new tooth. Identifying three developmental phases for each tooth unit, the researchers conclude that the alligator dental laminae contain what appear to be stem cells from which new replacement teeth develop.
“Stem cells divide more slowly than other cells,” said co-author Randall B. Widelitz, Ph.D., associate professor of pathology at the Keck School of Medicine. “The cells in the alligator’s dental lamina behaved like we would expect stem cells to behave. In the future, we hope to isolate those cells from the dental lamina to see whether we can use them to regenerate teeth in the lab.”
The researchers also intend to learn what molecular networks are involved in repetitive renewal and hope to apply the principles to regenerative medicine in the future.
The authors also report novel cellular mechanisms by which the tooth unit develops in the embryo and molecular signaling that speeds growth of replacement teeth when functional teeth are lost prematurely.
No Need To Toss Your Toothbrush After A Sore Throat
Word on the street has it you should replace your toothbrush after suffering from a cold, the flu or a bout of strep throat. That may not be necessary – at least when it comes to sore throats, according to a study presented at the Pediatric Academic Societies (PAS) annual meeting in Washington, DC.
Some health care professionals advise children to toss their toothbrushes if they have been diagnosed with strep throat. Researchers from University of Texas Medical Branch (UTMB) at Galveston wanted to determine if that advice is warranted.
First, they tried to grow group A Streptococcus (GAS), the bacteria that causes strep throat, on toothbrushes that had been exposed to the bacteria in a laboratory. The bacteria did in fact grow and remained on the toothbrushes for at least 48 hours.
Surprisingly, two new toothbrushes that were not exposed to GAS and served as controls also grew bacteria even though they had been removed from their packaging in a sterile fashion. An adult-size toothbrush grew gram-negative bacilli, and a child-size toothbrush grew gram-positive cocci, which was identified as Staphylococcus. Since this was not the main focus of the study, the researchers did not investigate this finding further.
Next, they investigated whether GAS would grow on toothbrushes used by children who had strep throat. Fourteen patients who were diagnosed with strep throat, 13 patients with sore throats without strep and 27 well patients ages 2 to 20 years were instructed to brush their teeth for one minute with a new toothbrush. Afterwards, the toothbrushes were placed in a sterile cover and taken to a lab where they were tested for GAS bacteria growth.
GAS was recovered from only one toothbrush, which had been used by a patient without strep throat. The other study toothbrushes failed to grow GAS but did grow other bacteria that are common in the mouth.
“This study supports that it is probably unnecessary to throw away your toothbrush after a diagnosis of strep throat,” said co-author Judith L. Rowen, MD, associate professor of pediatrics in the Department of Pediatrics at UTMB.
Study co-author Lauren K. Shepard, DO, a resident physician in the Department of Pediatrics at UTMB, noted that the study was small. Larger studies with more subjects need to be conducted to confirm that group A Streptococcus does not grow on toothbrushes used at home by children with strep throat, she said.
Article from: Medical News Today