Helicobacter pylori
Helicobacter pylori is a
bacterium that infects the
mucus lining of the human
stomach. It belongs among the
proteobacteria. Many peptic ulcers and some types of gastritis are caused by
H. pylori infection, although most humans are infected and many infections do not lead to any symptoms. Treatment of these diseases now often includes
antibiotics. Long term infection with the bacterium may also be associated with
gastric cancer.
About 2/3 of the world population are infected by the bacterium. Under poor sanitory conditions, one commonly finds infected children; in the U.S, older people (about 50% of those over the age of 60, 20% of those under the age of 40) and poor people are more likely to be infected. The infection apparently persists for life; the immune system cannot fend of the organism. The bacteria have been isolated from feces, saliva and dental plaque of infected patients, which suggests possible transmission routes.
One can test for H. pylori infection with blood antibody tests, breath tests (where the patient drinks 14C or 13C labeled urea, which the bacterium metabolizes to carbon dioxide that can be detected in the breath), or endoscopy.
H. pylori is a spiral-shaped
gram-negative bacteria, about
3 micrometers long with a diameter of about 0.5 micrometers. It has 4-6
flagella. It is microaerophilic, i.e. it requires
oxygen but at lower levels than those contained in the
atmosphere.
Several strains are known, and the genomes of two have been completely
sequenced.
With its flagella and its spiral shape, it drills through the mucus layer of the stomach and attaches to epithelial cells. It contains the enzyme urease which converts urea into ammonia and bicarbonate. The ammonia is useful to the bacterium since it partially neutralizes the very acidic environment of the stomach (whose very purpose is to kill bacteria). Ammonia is however toxic to the epithelial cells.
The bacterium and its link to peptic ulcers was described first in 1982 by two Australian researchers: Robin Warren and Barry Marshall. Before the discovery, stress or diet were considered the primary causes of these ulcers. They were treated with drugs that neutralize stomach acid or decrease its production. While this worked well, the ulcers very often reappeared. Acceptance in the medical community of the role of H. pylori was slow. In 1994, the NIH conducted a conference which ended with a consensus statement affirming the causative role of H. pylori in these diseases.
The bacterium was initially called Campylobacter pyloridis, then C. pylori and finally placed in its own genus Helicobacter. Some other species of that genus have now been identified in the stomachs of other mammals and some birds.
Links
In the News
Fastest Glacier In Greenland Doubles Speed
When people talk about something moving at a glacial pace, they are referring to speeds that make a tortoise look like a hare. While it is all relative, glaciers actually flow at speeds that require time lapses to recognize. Still, researchers who study Earth's ice and the flow of glaciers have been surprised to find the world's fastest glacier in Greenland doubled its speed between 1997 and 2003. [Odd] A Romanian couple has named their son Yahoo as a sign of gratitu
Daily Libertatea said on Thursday Cornelia and Nonu Dragoman, both from Transylvania, met and decided they were meant for each other following a three-month relationship over the net.They married and had a baby this Christmas, whom they decided to name after one of the worldwide web's most popular portals."We named him Lucian Yahoo after my father and the net, the main beacon of my life,"Cornelia Dragoman was quoted as saying. Rants &Raves: Forgive Me, Father
Readers vocalize their opinions on crime, punishment and respect for our fellow man. Enzyme Critical For Early Growth Of Abdominal Aortic Aneurysms
Surgery is the only treatment for an abdominal aortic aneurysm, a weak spot in the body's main artery that dilates dangerously over time. If the vessel ruptures suddenly before surgery to repair it, a quick death is virtually certain. Now, scientists say they have identified a key enzyme that triggers chronic inflammation in the aorta and promotes the growth of aneurysms. Their finding raises hopes for developing a drug that could prevent small aneurysms from enlarging to the point where surgery is necessary. Gas improves blood flow and organ status during minimally invasive sur
As good as laparoscopy is in preventing some of the stresses of open surgery on the body, it does have drawbacks, including reduced blood flow and organ dysfunction. By adding another gas to the carbon dioxide used to inflate the surgical area during laparoscopy, researchers have found they can preserve more normal blood flow during noninvasive surgery. Laparoscopy is a type of surgery in the abdomen done through small incisions. Crystal Sponges Excel At Sopping Up Carbon Dioxide
Since the Industrial Revolution, levels of carbon dioxide--a major contributor to the greenhouse effect--have been on the rise, prompting scientists to search for ways of counteracting the trend. One of the main strategies is removing carbon dioxide (CO2) from the flue exhaust of power plants, using porous materials that take up the gas as it travels up the flue. Childbirth Not Linked To Urinary Incontinence, Study Finds
Postmenopausal women who have given birth vaginally do not appear to suffer from urinary incontinence at higher rates than their sisters who have never given birth, according to a University of Rochester Medical Center study published in the December Obstetrics and Gynecology journal. [Ironic] LONDON: A jailed cocaine dealer is working as Santa Claus on
John Tams, who dons beard, boots and red suit to work in a cafe's Christmas grotto, said he wanted to give something back to the community... Scientists Discover How Body Fights To Control Spread Of Cancer
Scientists at the University of Liverpool have found how two molecules fight in the blood to control the spread of cancer cells. Keeping Cancer At Bay: Long-term Therapy In The Fight Against Multiple
There is no known cure for multiple myeloma, so its diagnosis means high-dose chemotherapy followed by repeated treatments with each relapse of the cancer -- a watch and wait approach. A new approach of providing patients with continuous therapy to keep the cancer at bay was explored by a team of international researchers from France, Switzerland and Belgium. Their findings will be published in the Nov. 15, 2006, issue of Blood.
MP3 Music Downloads
Preview songs, Download Free Music,Burn CDs at ITunes.com
 
|
