1941 Objectives SPECT in combination with CT enables a direct correlation of anatomic information and functional definition of scintigraphic findings. However patient is exposed to both internal radiation due to radiopharmaceuticals and transmission radiation due to CT. While internal radiation dose can be simulated with Monte Carlo method for most commonly used radiopharmaceuticals, organ specific radiation absorbed doses by CT irradiation should be measured to provide patient information and to optimize the clinical protocols. The effective dose due to CT can be summed together with effective dose due to emission to give the total patient effective dose to compare with radiation dose with other imaging technique. Methods With the use of thermoluminescence dosimeters (TLD-100H) and humanoid phantom, the organ absorbed doses were measured by irradiating the phantom with a SPECT/CT machine. As an example for discussion, a protocol for a clinical protocol for inflammation study was used, in that patient thorax, abdomen and part of pelvis were irradiated. Organ weighting factors from ICRP-103 were used to calculate the effective dose. Results Patient effective dose for inflammation protocol was measured as 4.62 mSv for female and 4.58 mSv for male adult. The slight difference in effective dose between both sex is the irradiated ovary in female and partially irradiation testis in male. As most radiation sensitive organs were irradiated in this inflammation study, the effective doses represent the maximum due to CT irradiation. Conclusions Effective dose due to CT irradiation from a SPECT/CT machine should be measured to provide patient information and to ensure optimized clinical protocol in imaging and dosimetry
Previous observational studies have not found a conclusive association between serum 25-hydroxyvitamin D (25(OH)D) levels and allergic rhinitis (AR) or allergic sensitization (AS).To investigate a causal association between 25(OH)D levels with risk of AR and AS, using a two-sample Mendelian randomization (MR) approach.Seven single nucleotide polymorphisms (SNPs), previously shown to be associated with serum 25(OH)D levels, were identified as instrumental variables. The primary outcome was AR, and the secondary outcomes were AS and non-allergic rhinitis (NAR). The genome-wide association (GWA) summary statistics of the outcomes were obtained from two cohort studies (EAGLE Consortium and UK Biobank). An MR analysis with random-effects inverse-variance weighted method was performed as the primary analysis to estimate overall effect size (odds ratio [OR] and 95% confidence interval [CI]). Sensitivity analysis using weighted median method and MR-Egger regression method was conducted. A subgroup analysis based on 25(OH)D synthesis-related SNPs was further applied.Serum 25(OH)D levels were not causally associated with risk of AR (OR: 0.960; 95% CI: 0.779-1.184), AS (OR: 1.059; 95% CI: 0.686 to 1.634) or NAR (OR: 0.937; 95% CI: 0.588-1.491). Subgroup analysis also showed null association between 25(OH)D synthesis-related SNPs and the outcomes. Sensitivity analyses yielded similar results.This MR study found no evidence supporting a causal association between serum 25(OH)D levels and risk of AR, AS and NAR in European-ancestry population. This argues against the previous postulation that vitamin D supplementation is effective in prevention of allergic diseases.
<i>Background:</i> Cholesterol metabolism has been implicated in the pathophysiology of Alzheimer’s disease (AD), and cholesterol-related genes are plausible candidate genes for AD. Genetic association of <i>CYP46A1</i> polymorphisms with AD had been under extensive investigations; however, observations on intron 2 T→C (rs754203) generated inconclusive results. <i>Objective:</i> To analyse an independent data set in a Chinese population to see whether the polymorphic site rs754203 of the <i>CYP46A1</i> gene is associated with AD. <i>Methods:</i> We analysed 130 sporadic AD patients and 110 healthy controls of the Southern Chinese origin. <i>Results:</i> An association between the genotype frequency and AD was suggested in the general population (p = 0.047, odds ratio, OR = 1. 61, 95% confidence interval, CI = 0.96–2.70), while the association was most significant in the apolipoprotein E <i>(ApoE)</i> Ε4-negative group (p = 0.004, OR = 2.54, 95% CI =1.31–4.95). Linkage disequilibrium block prediction results also favoured this association. Consistent with previous reports, intron 3 C→T (rs4900442) polymorphism did not show any evidence of association; in our data set <i>ApoE</i>Ε<i>4</i> was confirmed to be a genetic risk factor for AD (p = 0.0016, OR = 2.76, 95% CI = 1.50–5.11).
Fibrinogen, an acute phase protein, is an important inflammatory marker that is associated with cardiovascular diseases. We studied the association of three common human fibrinogen-beta gene (FGB) variants, -455G>A, -249C>T, and -148C>T with glycemic parameters in 265 non-diabetic Hong Kong Chinese subjects. Both FGB variants, -455G>A and -148C>T were in complete linkage disequilibrium and were associated with higher levels of plasma fibrinogen and 2-h glucose after a 75-g oral glucose load (p<0.01). Carriers of FGB AC-haplotype, comprising the two nucleotide variants at positions -455 and -249, had higher fibrinogen level (2.64 +/- 0.65 vs 2.42 +/- 0.52 g/L, p=0.002) and 2-h glucose after a 75-g oral glucose load (5.87 +/- 1.14 vs 5.47 +/- 1.22 g/L, p=0.006). The associations were significant in men, but not women. In stepwise multiple regression analysis, AC-haplotype was independently associated with plasma fibrinogen level and 2-h glucose (p=0.002 and 0.010 respectively). This suggests that fibrinogen may play a role in the development of impaired glucose tolerance.
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