Long-term mutagenic effects of ionising radiation on mice which vary in their p53 status

The tumor suppressor gene p53 plays a major role in the maintenance of genomic integrity. The impact that variations in cellular turnover rates and sensitivity to DNA damage will have on the effectiveness of p53 in this role was examined by following the induction and persistence of mutations in the brain and small intestine of mice after exposure to ionising radiation (IR). The examination of mutagenesis was carried out using the pUR288 LacZ plasmid-based mouse model-consisting of mice containing a target gene for mutation analysis integrated into every cell. In addition the mice varied in their p53 status. The tissues were compared at post-irradiation time-points from 24h to 3 months. The mutation frequencies (MFs) in the p53 wildtype and heterozygous brains peaked at 24h post-irradiation, and then returned to background or close to background levels, respectively. The p53 nullizygous brain showed a more fluctuating MF pattern, but returned to background levels by 3 months, indicating that the effect of the loss of p53 did not result in lasting differences in the response to mutation induction in the brain. In the intestine, there was a different pattern; in the wildtype and heterozygous animals, the MFs increased from 24h to a peak at 4 weeks post-irradiation, before decreasing towards background levels at 3 months. The MFs in the intestine from the nullizygous animals did not decrease significantly between 4 weeks and 3 months, illustrating that the loss of p53 had a greater impact in this tissue than the brain. The variation in mutation frequencies and the type of mutations generated after DNA damage suggests that while p53 plays a significant role in the maintenance of genomic integrity, other mechanisms, such as the drive to replicate in progenitor cells, can reduce its effectiveness as the "guardian of the genome".     

Chemical and principal-component analyses of the essential oils of Apioideae taxa (Apiaceae) from central Balkan

The volatile constituents of the essential oils of 23 taxa belonging to the Apioideae subfamily were studied in detail. The investigated taxa were Pimpinella serbica (Vis.) Bentham & Hooker, Libanotis montana Cr., Cnidium silaifolium (Jacq.) Simk. ssp. orientale (Boiss.) Tutin, Bupleurum praealtum L., B. sibthorpianum S. S. var. diversifolium (Roch.) Hay, Aegopodium podagraria L., Torilis anthriscus (L.) Gmel., Orlaya grandiflora (L.) Hoffm., Laserpitium siler L., Laser trilobum (L.) Brokh., Chaerophyllum aureum L., C. hirsutum L., C. temulum L., Pastinaca sativa L., P. hirsuta Pancic., Tordylium maximum L., Physospermum cornubiense (L.) DC., Peucedanum alsaticum L., P. oreoselinum (L.) Moench, P. cervaria (L.) Cuss., P. austriacum (Jacq.) Koch, P. longifolium W. et K., and P. officinale L. All of these species grow wild in the central part of the Balkan Peninsula. The essential oils were found to be complex mixtures of various compounds, more than 100 constituents being in each taxon, with contributions of main products never exceeding 25% of the total content. Sesquiterpene hydrocarbons were found to be the main group of constituents of all taxa, except for Peucedanum species, where monoterpene hydrocarbons were identified as the main components. The chemotaxonomic value of the essential-oil composition is discussed according to results of principal-component analysis (PCA). The essential-oil composition mainly reflects current taxonomic relationships between the investigated taxa.     

Acid cleavable PEG-lipids for applications in a ternary gene delivery vector

A novel class of pH-sensitive PEG lipids bearing acid-cleavable acetal linkages and short PEG chains have been synthesised and used in ternary vector formulations. The cleavage pH was influenced by structural components including the terminal PEG moiety and spacer length.     

General practitioner attitudes towards referral of eating-disordered patients: a vignette study based on the theory of planned behaviour

Objective The study examined individual differences between general practitioners (GPs) to determine their impact on variations in intention to refer a hypothetical patient with disordered eating to specialist eating disorder services. The study also examined the impact of patient weight on intention to refer.Method GPs within three primary care trusts (PCTs) were posted a vignette depicting a patient with disordered eating, described as either normal weight or underweight. A questionnaire was developed from the theory of planned behaviour to assess the GPs' attitudes, perception of subjective norms, perceived behavioural control, and intention to refer the patient. Demographic details were also collected.Results Responses were received from 88 GPs (33%). Intention to refer the patient was significantly related to subjective norms and cognitive attitudes. Together these predictors explained 86% of the variance in the intention to refer. GP or practice characteristics did not have a significant effect on the GPs' intention to refer, and nor did the patient's weight.Conclusion Despite National Institute for Health and Clinical Excellence current guidance, patient weight did not influence GPs' decisions to refer. Much of the variance in actual referral behaviour may be explained by cognitive attitudes and subjective norms. Interventions to reduce this variation should be focused on informing GPs about actual norms, and best practice guidelines.     

Fueling the Obesity Epidemic? Artificially Sweetened Beverage Use and Long‐term Weight Gain

We have examined the relationship between artificially sweetened beverage (ASB) consumption and long-term weight gain in the San Antonio Heart Study. From 1979 to 1988, height, weight, and ASB consumption were measured among 5,158 adult residents of San Antonio, Texas. Seven to eight years later, 3,682 participants (74% of survivors) were re-examined. Outcome measures were incidence of overweight/obesity (OW/OB(inc)) and obesity (OB(inc)) (BMI > or = 25 and > or = 30 kg/m(2), respectively), and BMI change by follow-up (DeltaBMI, kg/m(2)). A significant positive dose-response relationship emerged between baseline ASB consumption and all outcome measures, adjusted for baseline BMI and demographic/behavioral characteristics. Consuming >21 ASBs/week (vs. none) was associated with almost-doubled risk of OW/OB (odds ratio (OR) = 1.93, P = 0.007) among 1,250 baseline normal-weight (NW) individuals, and doubled risk of obesity (OR = 2.03, P = 0.0005) among 2,571 individuals with baseline BMIs <30 kg/m(2). Compared with nonusers (+1.01 kg/m(2)), DeltaBMIs were significantly higher for ASB quartiles 2-4: +1.46 (P = 0.003), +1.50 (P = 0.002), and +1.78 kg/m(2) (P < 0.0001), respectively. Overall, adjusted DeltaBMIs were 47% greater among artificial sweetener (AS) users than nonusers (+1.48 kg/m(2) vs. +1.01 kg/m(2), respectively, P < 0.0001). In separate analyses--stratified by gender; ethnicity; baseline weight category, dieting, or diabetes status; or exercise-change category--DeltaBMIs were consistently greater among AS users. These differences, though not significant among exercise increasers, or those with baseline diabetes or BMI >30 kg/m(2) (P = 0.069), were significant in all 13 remaining strata. These findings raise the question whether AS use might be fueling--rather than fighting--our escalating obesity epidemic.     

Detection and molecular characterization of 9,000-year-old Mycobacterium tuberculosis from a Neolithic settlement in the Eastern Mediterranean

Background

Mycobacterium tuberculosis is the principal etiologic agent of human tuberculosis. It has no environmental reservoir and is believed to have co-evolved with its host over millennia. This is supported by skeletal evidence of the disease in early humans, and inferred from M. tuberculosis genomic analysis. Direct examination of ancient human remains for M. tuberculosis biomarkers should aid our understanding of the nature of prehistoric tuberculosis and the host/pathogen relationship.

Methodology/Principal Findings

We used conventional PCR to examine bone samples with typical tuberculosis lesions from a woman and infant, who were buried together in the now submerged site of Atlit-Yam in the Eastern Mediterranean, dating from 9250-8160 years ago. Rigorous precautions were taken to prevent contamination, and independent centers were used to confirm authenticity of findings. DNA from five M tuberculosis genetic loci was detected and had characteristics consistent with extant genetic lineages. High performance liquid chromatography was used as an independent method of verification and it directly detected mycolic acid lipid biomarkers, specific for the M. tuberculosis complex.

Conclusions/Significance

Human tuberculosis was confirmed by morphological and molecular methods in a population living in one of the first villages with evidence of agriculture and animal domestication. The widespread use of animals was not a source of infection but may have supported a denser human population that facilitated transmission of the tubercle bacillus. The similarity of the M. tuberculosis genetic signature with those of today gives support to the theory of a long-term co-existence of host and pathogen.     

Sensitivity of IFN-γ Release Assay to Detect Latent Tuberculosis Infection Is Retained in HIV-Infected Patients but Dependent on HIV/AIDS Progression

Background

Detection and treatment of latent TB infection (LTBI) in HIV infected individuals is strongly recommended to decrease morbidity and mortality in countries with high levels of HIV.

Objective

To assess the validity of a newly developed in-house ELISPOT interferon-γ release assay (IGRA) for the detection of LTBI amongst HIV infected individuals, in comparison with the Tuberculin Skin Test (TST).

Methodology/Principal Findings

ESAT6/CFP10 (EC) ELISPOT assays were performed, together with a TST, in 285 HIV infected individuals recruited in HIV clinics in Dakar, Senegal, who had no signs of active TB at time of enrolment. Thirty eight of the subjects (13.3%) failed to respond to PHA stimulation and were excluded from the analysis. In the 247 remaining patients, response to PHA did not vary according to CD4 cell count categories (p = 0.51). EC ELISPOT was positive in 125 (50.6%) subjects, while 53 (21.5%) had a positive TST. Concordance between EC ELISPOT and TST was observed in 151 patients (61.1%) (kappa = 0.23). The proportion of subjects with a positive response to the EC ELISPOT assay decreased with declining CD4 counts (p trend = 0.001), but were consistently higher than the proportion of TST responders. In multivariate analysis, the risk of being EC-ELISPOT positive in HIV infected individuals was associated with age, CD4 count and HIV-1 strain.

Conclusion

Our study indicates that IGRAs using M. tuberculosis specific antigens are likely to retain their validity for the diagnosis of LTBI among HIV positive individuals, but may be impaired by T-cell anergy in severely immuno-suppressed individuals.