Helicobacter pylori infection in peptic ulcer disease: the importance of smoking and ethnicity

This study was conducted to determine the prevalence of Helicobacter pylori (H. pylori) and its associated factors among patients with peptic ulcer disease in Taiping Hospital. Consecutive peptic ulcer disease patients who had undergone esophagogastro-duodenoscopy were included. The H. pylori status was assessed by the rapid urease test. We excluded those who had active bleeding, a perforated peptic ulcer, severe vomiting, a history of gastric surgery, peptic ulcer disease or renal or liver diseases, carcinoma of the stomach, and recent use of antibiotics or proton pump inhibitors. Socio-demography, H. pylori status, medication history and other relevant clinical data were collected from case notes. A total of 416 subjects were selected, 49.7% were positive and 50.3% were negative for H. pylori infection. There were significant associations between H. pylori and age, ethnicity, smoking status and NSAID usage. However, there were no significant relationships between H. pylori status and gender or type of peptic ulcer. Multiple logistic regression showed that other ethnicities than Malays and smokers had a higher risk of H. pylori. Our prevalence rate was low and the identified risk factors were consistent with previous studies. Ethnic differences may be related to genetic and sociocultural behaviors. Quitting smoking may benefit peptic ulcer patients with H. pylori infection.

Neutron yields from 435 MeV/nucleon Nb stopping in Nb and 272 MeV/nucleon Nb stopping in Nb and Al

Neutron fluences were measured from 435 MeV/nucleon Nb ions stopping in a Nb target and 272 MeV/nucleon Nb ions stopping in targets of Nb and Al for neutrons above 20 MeV and at laboratory angles between 3 degrees and 80 degrees. The resultant spectra were integrated over angles to produce neutron energy distributions and over energy to produce neutron angular distributions. The total neutron yields for each system were obtained by integrating over the angular distributions. The angular distributions from all three systems are peaked forward, and the energy distributions from all three systems show an appreciable yield of neutrons with velocities greater than the beam velocity. Comparison of the total neutron yields from the two Nb + Nb systems suggests that the average neutron multiplicity decreases with decreasing projectile energy. Comparison of the total yields from the two 272 MeV/nucleon systems suggests that the total yields show the same dependence on projectile and target mass number as do total inclusive neutron cross sections. The data are compared with Boltzmann-Uehling-Uhlenbeck model calculations.

Production of neutrons from interactions of GCR-like particles

In order to help assess the risk to astronauts due to the long-term exposure to the natural radiation environment in space, an understanding of how the primary radiation field is changed when passing through shielding and tissue materials must be obtained. One important aspect of the change in the primary radiation field after passing through shielding materials is the production of secondary particles from the breakup of the primary. Neutrons are an important component of the secondary particle field due to their relatively high biological weighting factors, and due to their relative abundance, especially behind thick shielding scenarios. Because of the complexity of the problem, the estimation of the risk from exposure to the secondary neutron field must be handled using calculational techniques. However, those calculations will need an extensive set of neutron cross section and thicktarget neutron yield data in order to make an accurate assessment of the risk. In this paper we briefly survey the existing neutron-production data sets that are applicable to the space radiation transport problem, and we point out how neutron production from protons is different than neutron production from heavy ions. We also make comparisons of one the heavy-ion data sets with Boltzmann-Uehling-Uhlenbeck (BUU) calculations.