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Genomes of two H. pylori strains reveal few clues
Gastroenterology News continued
‘‘I think (irradiation) is a very good idea, but it will face lots of opposition,’’ predicts Dr. Ralph Giannella of the University of Cincinnati, who is president-elect of the AGA. Giannella points out that the food industry welcomes the technology as another tool to ensure that the food supply is safer, but vocal consumer groups continue to contend either that it is harmful, that it changes the taste and reduces the vitamins and nutrients in the meat, or both. ‘‘There’s no data to support these concerns,’’ Giannella asserts. ‘‘People
just assume that if it’s radiation, it must be bad.’’ Opponents have also argued that efforts to keep the meat supply safe should be focused not on treating the food, but on cleaning the processing plants so that the meat doesn’t become contaminated in the first place. Giannella says that some progress has been made in that area in the last couple of years, most notably through a program in which samples are sent directly by the meat-
processing plants to government agencies that test the meat for bacteria. ‘‘The statistics show that contamination of meat and poultry has dropped significantly in the last year as a consequence of the recent changes,’’ says Giannella. ‘‘There’s still room for continued improvement, and by all means, energy should be expended in keeping the plants clean. But that doesn’t mean we can’t also benefit from this safe technology for treating the meat.’’
GLP-2 Cloning May Lead to Therapy for Intestinal Deficiency Diseases
the paper, Daniel Drucker from the University of Toronto, to cause increased villus height and weight in the small intestine and to reduce the severity of experimental colitis. It also has been shown by other investigators to increase intestinal glucose transport, to enhance the adaptive response to massive intestinal resection, and to stimulate colonic growth. Analogs of GLP-2 that have been developed are degraded less rapidly and have greater activity than the native peptide. The need for an effective agent to enhance intestinal mucosal growth and regeneration is potentially great, and, with the receptor in hand, work to develop even more potent and long-acting GLP-2–like drugs can proceed. In addition to patients with intestinal resections or inflammatory or immune disease of the mucosa,
intestinal mucosal hypoplasia is common in patients receiving cancer chemotherapy or radiation therapy. Dr. Steve Cohn of the University of Virginia comments that ‘‘It will be important to establish that growthpromoting GLP-2 receptors are not present on tumors being treated. Otherwise, the beneficial effects of mucosal protection might be outweighed by decreased antitumor effects of chemotherapy or radiation therapy.’’ Cohn points out that GLP-2 is only one of several agents, including fibroblast growth factor, keratinocyte growth factor, interleukin 11, and trefoil factors, that are undergoing evaluation for protecting the intestinal mucosa against damage during cancer treatment, and that the same problem of specificity for normal mucosa rather than tumor cells could apply to all of them.
hypervariable region. The clinical significance of this report is quite limited, as pointed out by Dr. Martin Blaser of Vanderbilt University. Both strains were positive for the cagA gene that has been associated with pathogenicity. However, knowledge of the detailed structure of these two organisms should greatly simplify the process of designing molecular
probes to test specific hypotheses related to pathogenicity in organisms isolated from patients with different manifestations of chronic H. pylori infection.
step toward development of drugs that increase intestinal mucosal growth was taken with the cloning of the receptor for glucagonlike peptide 2 (GLP-2). The cDNA structure of this G protein–coupled receptor was reported by Munroe et al. in the Proceedings of the National Academy of Sciences, U.S.A. (February 16). GLP-2 acted with high affinity on this receptor to increase cyclic AMP production. The receptor gene is located on human chromosome 17. GLP-2 is a product of the preproglucagon gene and is distinct from glucagon or glucagon-like peptide 1. This 33–amino acid peptide previously was shown by one of the authors of
A
Genomes of Two H. pylori Strains Reveal Few Clues he complete genetic structures of two unrelated strains of Helicobacter pylori were reported and compared by Alm et al. in Nature ( January 14). Almost 93% of the genomes were identical, and half of the differences were clustered in one
T
786
Stories by Dan Gordon The section editor can be sent suggestions for articles at [email protected]
‘‘I think (irradiation) is a very good idea, but it will face lots of opposition,’’ predicts Dr. Ralph Giannella of the University of Cincinnati, who is president-elect of the AGA. Giannella points out that the food industry welcomes the technology as another tool to ensure that the food supply is safer, but vocal consumer groups continue to contend either that it is harmful, that it changes the taste and reduces the vitamins and nutrients in the meat, or both. ‘‘There’s no data to support these concerns,’’ Giannella asserts. ‘‘People
just assume that if it’s radiation, it must be bad.’’ Opponents have also argued that efforts to keep the meat supply safe should be focused not on treating the food, but on cleaning the processing plants so that the meat doesn’t become contaminated in the first place. Giannella says that some progress has been made in that area in the last couple of years, most notably through a program in which samples are sent directly by the meat-
processing plants to government agencies that test the meat for bacteria. ‘‘The statistics show that contamination of meat and poultry has dropped significantly in the last year as a consequence of the recent changes,’’ says Giannella. ‘‘There’s still room for continued improvement, and by all means, energy should be expended in keeping the plants clean. But that doesn’t mean we can’t also benefit from this safe technology for treating the meat.’’
GLP-2 Cloning May Lead to Therapy for Intestinal Deficiency Diseases
the paper, Daniel Drucker from the University of Toronto, to cause increased villus height and weight in the small intestine and to reduce the severity of experimental colitis. It also has been shown by other investigators to increase intestinal glucose transport, to enhance the adaptive response to massive intestinal resection, and to stimulate colonic growth. Analogs of GLP-2 that have been developed are degraded less rapidly and have greater activity than the native peptide. The need for an effective agent to enhance intestinal mucosal growth and regeneration is potentially great, and, with the receptor in hand, work to develop even more potent and long-acting GLP-2–like drugs can proceed. In addition to patients with intestinal resections or inflammatory or immune disease of the mucosa,
intestinal mucosal hypoplasia is common in patients receiving cancer chemotherapy or radiation therapy. Dr. Steve Cohn of the University of Virginia comments that ‘‘It will be important to establish that growthpromoting GLP-2 receptors are not present on tumors being treated. Otherwise, the beneficial effects of mucosal protection might be outweighed by decreased antitumor effects of chemotherapy or radiation therapy.’’ Cohn points out that GLP-2 is only one of several agents, including fibroblast growth factor, keratinocyte growth factor, interleukin 11, and trefoil factors, that are undergoing evaluation for protecting the intestinal mucosa against damage during cancer treatment, and that the same problem of specificity for normal mucosa rather than tumor cells could apply to all of them.
hypervariable region. The clinical significance of this report is quite limited, as pointed out by Dr. Martin Blaser of Vanderbilt University. Both strains were positive for the cagA gene that has been associated with pathogenicity. However, knowledge of the detailed structure of these two organisms should greatly simplify the process of designing molecular
probes to test specific hypotheses related to pathogenicity in organisms isolated from patients with different manifestations of chronic H. pylori infection.
step toward development of drugs that increase intestinal mucosal growth was taken with the cloning of the receptor for glucagonlike peptide 2 (GLP-2). The cDNA structure of this G protein–coupled receptor was reported by Munroe et al. in the Proceedings of the National Academy of Sciences, U.S.A. (February 16). GLP-2 acted with high affinity on this receptor to increase cyclic AMP production. The receptor gene is located on human chromosome 17. GLP-2 is a product of the preproglucagon gene and is distinct from glucagon or glucagon-like peptide 1. This 33–amino acid peptide previously was shown by one of the authors of
A
Genomes of Two H. pylori Strains Reveal Few Clues he complete genetic structures of two unrelated strains of Helicobacter pylori were reported and compared by Alm et al. in Nature ( January 14). Almost 93% of the genomes were identical, and half of the differences were clustered in one
T
786
Stories by Dan Gordon The section editor can be sent suggestions for articles at [email protected]