329 research outputs found
Increased target volume and hydrogen content in [11C]CH4 production
Introduction
High starting radioactivity is usually advantageous for producing radiopharmaceuticals with high specific radioactivity. However, the [11C]CH4 yields from N2-H2 gas target fall short from theoretical amounts, as calculated from the cross section for the well-known 14N(p,Îą)11C nuclear reaction1. The beneficial effect of increased target chamber temperature on [11C]CH4 yields has recently been brought forward by us2 and others3. In addition to the temperature effect, our attention has also been on the hydrogen content factor.
This study intends to examine the N2-H2 target performance in a substantially larger target chamber and at higher temperatures than our setup before and compare the results to the existing data.
Materials and Methods
Aluminium bodied custom design target chamber is used in fixed 17 MeV proton beam irradiations. Target chamber is equipped with heating elements and cooling circuit for temperature control. In addition to the target chamber body temperature, the target gas loading pressure and irradiation current can be varied.
The irradiation product is collected into an ad-sorbent trap that was immersed in a liquid argon cooling bath within a dose calibrator.
Results and Conclusion
Pursued data will show [11C]CH4 saturation yields (Ysat [GBq/ÂľA]) at different irradiation and target parameters
Associations Between Daytime Sleepiness, Psychological Symptoms, Headache, and Abdominal Pain in Schoolchildren
Daytime sleepiness and different symptoms are common problems affecting health and well-being of schoolchildren. This population-based cohort study included 568 children who were followed from ages 10 to 15 years. Daytime sleepiness, headache, abdominal pain, and psychological symptoms (depression, irritability or bad temper, nervousness, anxiety, and dejection) were assessed by self-administered questionnaires. The prevalence of frequent daytime sleepiness was 13% at the ages of 10 and 12 years and increased significantly up to 24% at the age of 15 (p </p
Projecting long-term trends in mobility limitations: Impact of excess weight, smoking and physical inactivity
Background Policy makers need disability projections for planning adequate services and measures for health promotion. The aim of this study is to provide projections on severe mobility limitations up to year 2044 and illustrate how the projected prevalence and the number of persons with severe mobility limitations are affected by potential changes in the modifiable risk factors, namely excess weight, physical inactivity and smoking.Methods We analysed the nationally representative, repeated measures Health 2000 and 2011 Surveys (BRIF8901) with 8615 and 6740 participants, respectively, aged 18 years and older. Severe mobility limitations were defined as major difficulties or unable to walk about half a kilometre. We applied a multistate model on repeated measures to account for both individual risk factors and their changes over time.Results The number of people with severe mobility limitations was projected to double by the year 2044 in Finland, due to the rapid ageing of the population. Eliminating half of the excess weight would reduce their number by one-fifth, while reductions in the prevalence of smoking and physical inactivity would have a minor impact. Even if excess weight, smoking and physical inactivity were completely eliminated, the number of persons with severe mobility limitations is projected to increase.Conclusions Designing and implementing strategies to promote healthy weight are important to slow down the rapid increase in mobility limitations due to population ageing. Providing adequate health and social services for the increasing population with disabilities will nevertheless be an increasing national challenge.</div
Gastric cancer and Helicobacter pylori: a combined analysis of 12 case control studies nested within prospective cohorts
BACKGROUND: The magnitude of the association
between Helicobacter pylori and
incidence of gastric cancer is unclear. H
pylori infection and the circulating antibody
response can be lost with development
of cancer; thus retrospective studies
are subject to bias resulting from classifi-
cation of cases as H pylori negative when
they were infected in the past.
AIMS: To combine data from all case control
studies nested within prospective
cohorts to assess more reliably the relative
risk of gastric cancer associated with H
pylori infection.To investigate variation in
relative risk by age, sex, cancer type and
subsite, and interval between blood sampling
and cancer diagnosis.
METHODS: Studies were eligible if blood
samples for H pylori serology were collected
before diagnosis of gastric cancer in
cases. Identified published studies and two
unpublished studies were included. Individual
subject data were obtained for
each. Matched odds ratios (ORs) and 95%
confidence intervals (95% CI) were calculated
for the association between H pylori
and gastric cancer.
RESULTS: Twelve studies with 1228 gastric
cancer cases were considered. The association
with H pylori was restricted to noncardia
cancers (OR 3.0; 95% CI 2.3â3.8)
and was stronger when blood samples for
H pylori serology were collected 10+ years
before cancer diagnosis (5.9; 3.4â10.3). H
pylori infection was not associated with an
altered overall risk of cardia cancer (1.0;
0.7â1.4).
CONCLUSIONS: These results suggest that
5.9 is the best estimate of the relative risk
of non-cardia cancer associated with H
pylori infection and that H pylori does not
increase the risk of cardia cancer. They
also support the idea that when H pylori
status is assessed close to cancer diagnosis,
the magnitude of the non-cardia
association may be underestimated
The Association between the Preference for Active Play and Neurological Development in Toddlers: A Register-Based Study
Active play is regarded as physical activity during early childhood. Physical activity has many benefits for childrenâs physical and psychosocial health and wellbeing, as well as for their cognitive development. The aim of this study was to investigate associations between the preference for active play and neurological development in toddlers. The study was conducted as a register-based study, and the data were collected from a public-health clinicâs electronic health records. The register data about active play used in this study were originally assessed by parents at home and by early years teachers at nurseries. Neurological development was assessed by the public health nurses in public child-health clinics. The data eligible for this study were available from 717 toddlers aged 2.5â3.0 years old (mean: 2.5 years Âą 2 months). The majority of toddlers (85%) showed a preference for active play, both at home and at the nursery. The prevalence of delays in the neurological development of toddlers varied in different developmental areas (by 1â15%). Delays in gross motor competence, auditory perception, and self-help skills were associated with a lower preference for active play in nursery settings, but none of the neurodevelopmental items were found to be associated with toddlersâ preference for active play at home. Nurseries need to encourage children to actively play and support their gross motor competence and self-help skills.</p
A nested caseâcontrol study of the association of Helicobacter pylori infection with gastric adenocarcinoma in Korea
In a nested caseâcontrol study of 86 cases of gastric adenocarcinoma in relation to Helicobactor pylori infection in the Korean Multi-center Cancer Cohort, the H. pylori IgG seropositivity was 83.7% and that of the 344 matched controls was 80.8%, with a matched odds ratio for H. pylori infection of 1.06 (95% CI, 0.80â1.40)
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