H. pylori and gastric cancer

Treatment for the eradication of Helicobacter pylori appears to reduce the risk of gastric cancer, say Italian and US researchers. The association between gastric cancer and infection with H. pylori is well established, but the effect of eradication treatment has previously not been clarified. In a meta-analysis of six studies involving over 6000 patients in areas with a high incidence of gastric cancer, 1.1% of treated patients developed gastric cancer, compared with 1.7% of untreated patients. A pooled analysis of all the studies comparing eradication treatment for H. pylori to no intervention or placebo revealed a relative risk of 0.65. The authors conclude that, because of the high incidence of gastric cancer worldwide, even a small decrease with H. pylori eradication treatment will have major benefits.

Ann Intern Med 2009; 151: 121-128

VTE and travel: what are the risks?

There is considerable conflict between published studies about the real risk of venous thromboembolism (VTE) associated with travel. A US meta-analysis that included data on 4055 cases of VTE has confirmed the association and suggested a dose-response relationship between travel time and risk of VTE. Compared with non-travellers, the meta-analysis showed that travellers had an overall pooled relative risk of 2.0 for VTE. When differences between selection criteria for control subjects were accounted for by excluding control patients who had been referred for VTE evaluation, the relative risk rose to 2.8. Additionally, an 18% higher risk for VTE was observed for each 2-hour increase in travel time. The authors comment that the heterogeneity of study design not only makes comparisons and pooling of data difficult, but also highlights shortcomings in the understanding of basic principles of research design.

Ann Intern Med 2009; 151: 180-190

“Blindness” to fungal spores

Ever wondered why your respiratory system doesn’t react to the allergens and antigens contained in the thousands of fungal spores (conidia) you breathe in with each lungful of air? A group of European researchers appear to have found the answer, which lies in the presence of a surface layer on the dormant conidia that masks its recognition by the immune system and prevents an immune response. Using a number of fungi that can be opportunistically pathogenic, including Aspergillus fumigatus, they conducted in-vitro assays and in-vivo murine experiments. The surface “rodlet layer” of the conidia is composed of hydrophobic proteins bound to the cell wall, and is immunologically inert, failing to induce activation and maturation of dendritic cells or alveolar macrophages, or to activate helper T-cell immune responses. The authors comment on the exciting possibility of generating rodlet protein-based nanoparticles containing therapeutic substances, which could be transported through the body without recognition by the host immune system.

Nature 2009; 460: 1117-1121

Overweight kids

Despite national policies for the detection and management of overweight and obese children, it appears that screening for these children, followed by a short period of counselling in a primary care setting, may not be of benefit. Australian researchers conducted a randomised controlled trial involving over 200 overweight or obese children aged from 5 to 10 years. Participants were identified through measurement of body mass index (BMI) by their general practitioner, and placed into intervention and control groups. The intervention consisted of four consultations over a 12-week period, which aimed to create change in nutrition and physical activity, along with educational materials for the family. No significant improvements were observed in BMI, physical activity, or nutrition in the intervention group compared with the controls at 6 and 12 months. Despite the limitation of a smaller number of participants than planned, the authors comment that the trial suggests international policies on childhood obesity recommending GP surveillance and a brief period of counselling are not likely to be successful in the fight against obesity.

BMJ 2009; 339: b3308

Dr Tanya Grassi, MJA

©The Medical Journal of Australia 2009 www.mja.com.au PRINT ISSN: 0025-729X ONLINE ISSN: 1326-5377