RSS Feeds

Earth Science

Space Science

Life Science

Fields of Scientific Study

Nanotechnology

Cancer

Definitions of The Fields of Scientific Study

After a 40-year search, a hormone controlling iron metabolism in mammals is finally identified

April 03, 2002

Iron is vital for cells, because it catalyzes key enzyme reactions; it is also crucial for respiration, fixing atmospheric oxygen to hemoglobin in red blood cells. Iron deficiency can lead to severe anemia, with inadequate tissue oxygenation. An excess of iron is also toxic, as it facilitates the generation of free radicals that can attack the liver, heart and pancreas. This is the case in hereditary hemochromatosis, a genetic disorder which, in 80% of cases, is linked to a point mutation in the Hfe-1 gene, leading to excessive iron uptake by the intestinal tract. Hereditary hemochromatosis is very frequent in western countries, affecting one in 300 people. The body has no physiological mechanism for eliminating iron, and the only effective treatment for patients with hereditary hemochromatosis is bleeding, in some cases several times a week. These patients, and their doctors, are eagerly awaiting a breakthrough in our understanding of the mechanisms regulating iron metabolism, that might have therapeutic implications.

Dietary iron enters the body via cells known as enterocytes, that line the intestinal folds. Humoral signals are known to modulate how much iron these cells take up, according to the body`s internal stores. Yet, despite intense research over the last four decades, no-one had previously been able to identify these signals.

It is by chance that Ga'�l Nicolas, Sophie Vaulont and their coworkers came across such a signal while working on knock-out mice developed in their laboratory. The mice lacked a transcription factor known as USF2 (upstream stimulatory factor 2), thought to be involved in glucose metabolism. To their surprise, the team found that the mice had disorders similar to those of patients with hereditary hemochromatosis, namely premature ageing of the pancreas and liver, which take on an abnormal brown color - a sign of iron accumulation. Further tests indeed showed that the animals had a form of hemochromatosis. Intrigued, the team created a subtractive RNA bank in order to determine whether any other genes were abnormally expressed in their model. This was effectively the case. One abnormally expressed gene was found to correspond to a recently identified sequence of 25 amino acids found in members of an antimicrobial peptide family called the defensins. The peptide in question - hepcidin - is produced by the liver and secreted into the bloodstream. Hepcidin has a degree of antimicrobial activity, but Axel Kahn, Sophie Vaulont and their colleagues at Bichat Hospital in Paris believe that it acts essentially as a true hormone, inhibiting iron uptake by intestinal cells; they also believe that when hepcidin dysfunctions the body has no way of limiting iron absorption into the bloodstream.

To test this hypothesis, the team first checked that iron levels were normal in a transgenic mouse model, produced in another laboratory, that lacks USF2 but has an intact hepcidin gene. Then they went on to create transgenic mice whose livers overproduced hepcidin, expecting them to develop anemia. In the event, almost all the new-born animals were smaller than normal, had very pale skin and no hair, were profoundly anemic, and died within hours of birth - unless they received an injection of iron. (Some animals producing less hepcidin were less severely anemic and survived without treatment.)

This discovery opens up exciting therapeutic and diagnostic perspectives in diseases due to abnormal iron homeostasis. Therefore, a patent application has been filed by INSERM and the inventors. One short-term possibility is a diagnostic test based on serum hepcidin measurement. In the longer term, the development of hepcidin agonists and antagonists may well transform the treatment of these frequent and potentially severe disorders.

Institut National de la Santé et de la Recherche Médicale - Tolbiac (INSERM)

Science Research Departments

	Scientific Explorer's Mind Blowing Science Kit for Young Scientists by Scientific Explorer Mind blowing experiments to delight and educate young scientists! Erupt a color changing volcano. Mix up magic ooze with a mind of its own. Play with sand that never gets wet. Mix safe chemicals and watch colors change before your eyes. You'll amaze yourself and your friends as you explore the science behind these truly remarkable reactions.
	The Everything Kids' Science Experiments Book: Boil Ice, Float Water, Measure Gravity-Challenge the World Around You! (Everything Kids Series) by Tom Robinson (Author) Science has never been so easy - or so much fun! With The Everything Kids' Science Experiments Book, all you need to do is gather a few household items and you can recreate dozens of mind-blowing, kid-tested science experiments. High school science teach Tom Robinson shows you how to expand your scientific horizons - from biology to chemistry to physics to outer space. You'll discover answers to questions like: Is it possible to blow up a balloon without actually blowing into it? What is inside coins? Can a magnet ever be "turned off"? Do toilets always flush in the same direction? Can a swimming pool be cleaned with just the breath of one person? Get ready to enter the laboratory and learn how to conduct cool experiments, understand scientific terms...
	Scientific Explorer's Disgusting Science - A Kit for Studying the Science of Revolting Things by Scientific Explorer Grow your own friendly germs and fuzzy molds. Mix up a batch of coagulating fake blood. Even make a stinky intestine. learn the science behind unmentionable bodily functions while doing some truly NASTY Experiments. Ages 8+
	The Science Book: Everything You Need to Know About the World and How It Works (National Geographic) by National Geographic (Author), Marshall Brain (Foreword) A delight for the casual reader, yet so complete and wide-ranging that science buffs and students will welcome it, The Science Book encapsulates centuries of scientific thought in one richly illustrated volume. Natural phenomena, revolutionary inventions, and the most up-to-date investigations are explained in detailed text, and 2,000 vivid illustrationsincluding 3-D graphics and pictogramsmake the information even more accessible and amazing to discover. The Science Book offers both a general overview of topics for the browsing reader and more specific information for those seeking deeper insight into a particular subject. Six major sections, ranging from the universe and planet Earth to biology, chemistry, physics, and mathematics, encompass everything from microscopic life...
	Scientific Explorer's The Magic Science Wizard's Kit by Scientific Explorer Cast real smoke from your fingertips, make a wizard wand, and whip up color-changing potions in your test tube laboratory. Also included are laminated cards with wizard facts, an instruction booklet with 11 activities, lab equipment, and mysterious wizard powders that will mix together to mystify you!
	Scientific Explorer's Tasty Science Chemistry in the Kitchen Kit by Scientific Explorer Who knew science could taste so good? With this kit, you’ll whip up cupcakes, cookies, candy, and more—all in the name of science! Learn what makes cakes rise, candy crystallize, and more real chemistry happen in the kitchen. Tasty Science is packed with ingredients, recipes, activity cards, a test tube laboratory, and lots more to explore the science of taste.
	The Complete Book of Science, Grades 5-6 by School Specialty Publishing (Author) The Complete Book of Science for grades 5 to 6 teaches children important science skills! Children complete a variety of exercises that help them develop a number of skills in this 352 page workbook. Including a complete answer key this workbook features a user-friendly format perfect for browsing, research, and review. Over 4 million in print! The best-selling Complete Book series offers a full complement of instruction, activities, and information about a single topic or subject area. Containing over 30 titles and encompassing preschool to grade 8 this series helps children succeed in every subject area! ...
	Magic School Bus Journey into the Human Body Science Kit by Young Scientist Club The Magic School Bus and Ms. Frizzle take Young Scientists on a wild ride into the human body with these breathtaking experiments. Young Scientists bend bones, make joints, map taste buds, expand lungs, build a stethoscope, measure lung capacities and heart rates, perform the iodine starch test, spin glitter, simulate synovial fluid, create a human body poster, and much, much more! This exciting kit includes a life-size poster with eight sheets of body part stickers. So put on your seat belts, students, and get ready to discover The Human Body!
	What Is the World Made Of? All About Solids, Liquids, and Gases (Let's-Read-and-Find-Out Science, Stage 2) by Kathleen Weidner Zoehfeld (Author), Paul Meisel (Author) Did you ever walk through a wall? Drink a glass of blocks? Have you ever played with a lemonade doll, or put on milk for socks? This latest addition to the Let's-Read-and-Find-Out Science series introduces the youngest readers to an important science concept: the differences between solids, liquids, and gases. Any child who wants to know why he can't walk through a wall will enjoy Kathleen Zoehfeld's simple text and Paul Meisel's playful illustrations.
	Scientific Explorer's Spa Science Chemistry Kit by Scientific Explorer Whip your bath into a frothy fizzing sea of color and fragrance. Make colorful, fragrant bath gels, bath fizzers, spa lotion, bath balm, a face mask, and shampoo. Mix colors and fragrances to creat your own product line with secret and exclusive mixtures. Explore the science of gels, fragrance and fizzers. Mixing fragrances in the bathtub is a delight for both girls and boys. It’s one of the best ways to introduce them to the fun of science. Kids will spend hours in the tub with this kit mixing ingredients to make foaming frothing baths and smelling potions and conducting science experiments to see how scents affect our alertness, moods and memories. Comparing the responses of siblings, parents and friends makes this a shared adventure the entire family will enjoy