Virus-specific CD8+ T lymphocytes within the normal human liver

The frequency and phenotype of human antiviral memory CD8(+) T cells in blood are well studied, yet little is known about their distribution within tissues. Analysis of antiviral CD8(+) T cell populations derived from a unique set of normal liver and blood samples identified a consistent population of virus-specific cells within the liver. In comparison to the circulating T cells, the liver-derived T cells were present at frequencies which were variably enriched compared to that in the blood, and showed significant differences with regard to the expression of CD45RA, CD45RO, CD95, CCR7, CD27 and CD28. The differences in these cell surface markers are consistent with a mature 'effector memory' phenotype of antigen-specific CD8(+) T cells within the liver. An enrichment of an activated subset of NKT cells (V alpha 24/V beta 11) was also observed, a finding which may be relevant to the regulation of the antiviral populations.     

Toxicity and immunogenicity of purified Haemophilus ducreyi cytolethal distending toxin in a rabbit model

The cytolethal distending toxin of Haemophilus ducreyi (HdCDT) is a three-component toxin that induces the arrest of the mammalian cell cycle in the G2 phase. All of the individual gene products, CdtA, CdtB and CdtC, are required for toxic activity on cultured mammalian cells. The CdtB component alone exerts nuclease activity. The individual HdCDT components were purified by affinity chromatography or ion-exchange chromatography followed by gel-filtration. HdCDT was reconstituted and purified by the immobilization of a GST-CdtB fusion on a GSTrap column and the subsequent addition of cell sonicates from Escherichia coli recombinants that produced CdtA and CdtC. The purified HdCDT preparation contained all three CDT proteins, as detected by immuno-blotting, and had high cytotoxic activity (10(6)CPU/ml). Immunization of rabbits with the HdCDT complex and with the individual CdtA, CdtB and CdtC proteins elicited high titres of antibodies, as detected by ELISA. All of the immune sera had toxin-neutralizing activities. The pathological effects of the HdCDT complex were investigated in rabbits, since the proliferation of two rabbit cell lines, SIRC and RK-13, was inhibited by HdCDT. Intradermal injection of HdCDT (1, 10, 50 and 100microg protein) into naive rabbits resulted in dose-dependent skin reactions (erythema) about 24h after injection. Similar effects were not observed when the individual HdCDT proteins were injected. HdCDT injection into immune rabbits resulted in dose-dependent skin responses that were characterized by both erythema and oedema. Histological evaluation of the 24-h lesions in naive rabbits that were injected with HdCDT, revealed moderate levels of inflammatory cells, which were mainly granulocytes and macrophages, and dilatation of blood vessels. The skin reactions in HdCDT-injected immunized rabbits showed pronounced vascular changes and extensive infiltration of inflammatory cells, including eosinophils. All of the pathological changes healed after 3 days. In conclusion, purified HdCDT holotoxin is a complex of all three CDT proteins and all three components induce neutralizing antibodies when injected in rabbits. HdCDT causes dose-dependent pathologic skin reactions in both naive and immune rabbits, which is characterized by increased inflammatory responsiveness after each immunization.     

Virulence of a hemB mutant displaying the phenotype of a Staphylococcus aureus small colony variant in a murine model of septic arthritis

Persistence of Staphylococcus aureus during invasive infections has been associated with a small-colony variant (SCV) phenotype. SCVs are frequently auxotrophic for menadione or hemin, two compounds involved in the biosynthesis of the electron transport chain. SCVs have been shown to be more resistant to antibiotics such as aminoglycosides, grow slowly and persist intracellularly. The aim of this study was to assess the virulence of an hemB mutant, which has been shown to display the typical characteristics of clinical SCVs, in a murine model of septic arthritis. NMRI mice were inoculated intravenously with either the wild type strain Newman or with its mutant displaying the SCV phenotype. The clinical, bacteriological, and histopathological progression of the disease was studied. Mice inoculated with the hemB mutant displayed a higher frequency and a significantly higher severity of arthritis than mice inoculated with the wild type Newman strain. Despite that, the mutant inoculated mice displayed significantly lower bacterial burden in their kidneys and joints compared with mice exposed to the wild parental strain. Notably, the hemB mutant produced almost 20 times more protease in vitro than the parental strain. We conclude that the small colony variants of S. aureus are more virulent on a per organism basis than its isogenic parental strain in the model of septic arthritis. This can at least in part be explained by the ability of SCV to produce high amounts of destructive proteases.     

Pooled cohort study on height and risk of cancer and cancer death

Purpose

To assess the association between height and risk of cancer and cancer death.

Methods

The metabolic syndrome and cancer project is a prospective pooled cohort study of 585,928 participants from seven cohorts in Austria, Norway, and Sweden. Hazard ratios (HRs) and 95 % confidence intervals (CIs) for cancer incidence and death were estimated in height categories and per 5-cm increment for each cancer site using Cox proportional hazards model.

Results

During a mean follow-up of 12.7 years (SD = 7.2), 38,862 participants were diagnosed with cancer and 13,547 participants died of cancer. Increased height (per 5-cm increment) was associated with an increased overall cancer risk in women, HR 1.07 (95 % CI 1.06–1.09), and in men, HR 1.04 (95 % CI 1.03–1.06). The highest HR was seen for malignant melanoma in women, HR 1.17 (95 % CI 1.11–1.24), and in men HR 1.12 (95 % CI 1.08–1.19). Height was also associated with increased risk of cancer death in women, HR 1.03 (95 % CI 1.01–1.16), and in men, HR 1.03 (95 % CI 1.01–1.05). The highest HR was observed for breast cancer death in postmenopausal women (>60 years), HR 1.10 (95 % CI 1.00–1.21), and death from renal cell carcinoma in men, HR 1.18 (95 % CI 1.07–1.30). All these associations were independent of body mass index.

Conclusion

Height was associated with risk of cancer and cancer death indicating that factors related to height such as hormonal and genetic factors stimulate both cancer development and progression.     

Prognostic significance of functional somatic symptoms in adolescence: a 15-year community-based follow-up study of adolescents with depression compared with healthy peers

Background

The prevalence of depression is increasing markedly in Thailand. One way of helping people with depression is to increase their resilience; good resilience is associated with positive outcomes in depression. The purpose of this study was to examine the effectiveness of a self-help manual on the resilience levels of individuals with depression living in the community in Chiang Mai Province in northern Thailand.

Methods

Fifty-six participants with a diagnosis of moderate depression were assigned randomly to either an intervention (n = 27) or control (n = 29) group by means of independent random allocation, using computer generated random numbers. Fifty-four completed the study (two were excluded shortly after baseline data collection), so an available case analysis was undertaken. The intervention group were given a self-help manual and continued to receive standard care and treatment, while the control group continued to receive standard care and treatment. Both groups were also given a short weekly telephone call from a researcher. Participants were assessed at three time points: baseline (Week 0), immediate post-test (Week 8), and follow-up (Week 12). Data were collected between October 2007 and April 2008.

Results

The findings showed statistically significant differences between the intervention and the control group, and within the intervention group, in their resilience levels. Simple main effects analyses of group within time showed a significant difference between both groups at follow-up (p = 0.001), with the intervention group having a higher resilience score than the control group. Simple main effect of time within the intervention group showed a significant increase in resilience scores from baseline to post-test time points (p < 0.001), from baseline to follow-up (p < 0.001), but not from post-test to follow-up (p = 0.298).

Conclusions

The findings provide preliminary evidence supporting the use of bibliotherapy for increasing resilience in people with moderate depression in a Thai context. Bibliotherapy is straightforward to use, and an easily accessible addition to the standard approach to promoting recovery. It is incorporated readily as an adjunct to the work of mental health nurses and other professionals in promoting resilience and enhancing recovery in people with moderate depression in the community.

Trial registration

http://www.ANZCTR.org.au/ACTRN12611000905965.aspx     

Brain tissue volumes in the general population of the elderly: the AGES-Reykjavik study

Imaging studies have reported conflicting findings on how brain structure differs with age and sex. This may be explained by discrepancies and limitations in study population and study design. We report a study on brain tissue volumes in one of the largest cohorts of individuals studied to date of subjects with high mean age (mean ± standard deviation (SD) 76 ± 6 years). These analyses are based on magnetic resonance imaging (MRI) scans acquired at baseline on 4303 non-demented elderly, and 367 who had a second MRI, on average 2.5 ± 0.2 years later. Tissue segmentation was performed with an automatic image analysis pipeline. Total brain parenchymal (TBP) volume decreased with increasing age while there was an increase in white matter hyperintensities (WMH) in both sexes. A reduction in both normal white matter (NWM)- and gray matter (GM) volume contributed to the brain shrinkage. After adjusting for intra-cranial volume, women had larger brain volumes compared to men (3.32%, p < 0.001) for TBP volume in the cross-sectional analysis. The longitudinal analysis showed a significant age-sex interaction in TBP volume with a greater rate of annual change in men (− 0.70%, 95%CI: − 0.78% to − 0.63%) than women (− 0.55%, 95%CI: − 0.61% to − 0.49%). The annual change in the cross-sectional data was approximately 40% less than the annual change in the longitudinal data and did not show significant age-sex interaction. The findings indicate that the cross-sectional data underestimate the rate of change in tissue volumes with age as the longitudinal data show greater rate of change in tissue volumes with age for all tissues.     

Comparison of strain typing results for Clostridium difficile isolates from North America

Accurate strain typing is critical for understanding the changing epidemiology of Clostridium difficile infections. We typed 350 isolates of toxigenic C. difficile from 2008 to 2009 from seven laboratories in the United States and Canada. Typing was performed by PCR-ribotyping, pulsed-field gel electrophoresis (PFGE), and restriction endonuclease analysis (REA) of whole-cell DNA. The Cepheid Xpert C. difficile test for presumptive identification of 027/NAP1/BI isolates was also tested directly on original stool samples. Of 350 isolates, 244 (70%) were known PCR ribotypes, 224 (68%) were 1 of 8 common REA groups, and 187 (54%) were known PFGE types. Eighty-four isolates typed as 027, NAP1, and BI, and 83 of these were identified as presumptive 027/NAP1/BI by Xpert C. difficile. Eight additional isolates were called presumptive 027/NAP1/BI by Xpert C. difficile, of which three were ribotype 027. Five PCR ribotypes contained multiple REA groups, and three North American pulsed-field (NAP) profiles contained both multiple REA groups and PCR ribotypes. There was modest concordance of results among the three methods for C. difficile strains, including the J strain (ribotype 001 and PFGE NAP2), the toxin A-negative 017 strain (PFGE NAP9 and REA type CF), the 078 animal strain (PFGE NAP7 and REA type BK), and type 106 (PFGE NAP11 and REA type DH). PCR-ribotyping, REA, and PFGE provide different but overlapping patterns of strain clustering. Unlike the other methods, the Xpert C. difficile 027/NAP1/BI assay gave results directly from stool specimens, required only 45 min to complete, but was limited to detection of a single strain type.     

The Application of a Bayesian Approach to the Analysis of a Complex,Mechanistically Based Model

The Bayesian approach has been suggested as a suitable method in the context of mechanistic pharmacokinetic-pharmacodynamic (PK-PD) modeling, as it allows for efficient use of both data and prior knowledge regarding the drug or disease state. However, to this day, published examples of its application to real PK-PD problems have been scarce.

We present an example of a fully Bayesian re-analysis of a previously published mechanistic model describing the time course of circulating neutrophils in stroke patients and healthy individuals.

While priors could be established for all population parameters in the model, not all variability terms were known with any degree of precision. A sensitivity analysis around the assigned priors used was performed by testing three different sets of prior values for the population variance terms for which no data were available in the literature: “informative”, “semi-informative”, and “noninformative”, respectively. For all variability terms, inverse gamma distributions were used.

It was possible to fit the model to the data using the “informative” priors. However, when the “semi-informative” and “noninformative” priors were used, it was impossible to accomplish convergence due to severe correlations between parameters. In addition, due to the complexity of the model, the process of defining priors and running the Markov chains was very time-consuming.

We conclude that the present analysis represents a first example of the fully transparent application of Bayesian methods to a complex, mechanistic PK-PD problem with real data. The approach is time-consuming, but enables us to make use of all available information from data and scientific evidence. Thereby, it shows potential both for detection of data gaps and for more reliable predictions of various outcomes and “what if” scenarios.     

Contrast Effects in Perceived Risk of Substance Use

Adolescent perceptions of the risks associated with the use of licit and illicit substances have important implications for policy and research. However, the methodological properties of the most popular risk measures in school surveys in Europe and the United States are not well understood. This study examines the potential contrast effects of risk measures of “heavy” and frequent substance use on perceived risks of occasional, moderate, and “experimental” use. Responses to 11 measures of the perceived risk of occasional smoking, moderate drinking, and experimental use of illicit substances were compared between two question forms administered to a split-half sample of all Icelandic ninth (14–15 years of age) and tenth (15–16 years of age) grade students present in class on the day of administration in March 2003 (N = 7099). In one form, only these 11 questions were used, while the other form also contained 13 questions on the perceived risk of heavy smoking, heavy drinking, and regular use of illicit substances. The longer form is found to decrease response rates and suppress estimates of perceived risk of experimental illicit substance use. Question form and perceived risks of heavy and regular use generally do not affect the multivariate effects of perceived risks of occasional, moderate, and experimental substance use on lifetime abstinence from each substance. It is argued that measures of perceived risks of heavy and regular substance use are less useful for prevention policy and research than are corresponding measures of occasional, moderate, and experimental substance use, and including the former in the same instrument may adversely affect the measurement of the latter constructs.