The estimation of absorbed dose rates for non-human biota: an extended intercomparison

An exercise to compare 10 approaches for the calculation of unweighted whole-body absorbed dose rates was conducted for 74 radionuclides and five of the ICRP's Reference Animals and Plants, or RAPs (duck, frog, flatfish egg, rat and elongated earthworm), selected for this exercise to cover a range of body sizes, dimensions and exposure scenarios. Results were analysed using a non-parametric method requiring no specific hypotheses about the statistical distribution of data. The obtained unweighted absorbed dose rates for internal exposure compare well between the different approaches, with 70% of the results falling within a range of variation of ±20%. The variation is greater for external exposure, although 90% of the estimates are within an order of magnitude of one another. There are some discernible patterns where specific models over- or under-predicted. These are explained based on the methodological differences including number of daughter products included in the calculation of dose rate for a parent nuclide; source-target geometry; databases for discrete energy and yield of radionuclides; rounding errors in integration algorithms; and intrinsic differences in calculation methods. For certain radionuclides, these factors combine to generate systematic variations between approaches. Overall, the technique chosen to interpret the data enabled methodological differences in dosimetry calculations to be quantified and compared, allowing the identification of common issues between different approaches and providing greater assurance on the fundamental dose conversion coefficient approaches used in available models for assessing radiological effects to biota.

Prevalence and characteristics of psoriatic arthritis in Chinese patients with psoriasis

BACKGROUND

The prevalence and clinical characteristics of psoriatic arthritis (PsA) in patients with psoriasis vary widely in different countries and studies on Chinese population are rarely reported.

OBJECTIVE

The aim of this study was to evaluate the prevalence and clinical characteristics of PsA in a Chinese population of patients with psoriasis.

METHODS

A large cross-sectional observational study was conducted in our outpatient dermatology department and consecutive psoriatic patients were evaluated for PsA according to Classification of Psoriatic arthritis (CASPAR) criteria. Demographic and medical parameters were recorded.

RESULTS

Among 1928 patients with psoriasis, 112 patients (5.8%) had PsA, of which 92% was newly diagnosed. Oligoarthritis (48.2%) was the most common manifestation pattern, followed by spondylitis (26.8%), polyarthritis (19.6%) and classic distal interphalangeal (DIP) arthritis (5.4%). Enthesitis was present in 26.8% and dactylitis in 13.4% of the patients. Compared with patients without PsA, patients with PsA had more severe skin disease (mean PASI 9.7 vs. 6.0), higher frequency of nail changes (46.4% vs. 21.0%) and scalp involvement (90.2% vs. 76.4%).

CONCLUSION

The findings are consistent with a low prevalence of PsA among patients with psoriasis in Asia and confirm a high percentage of undiagnosed cases with active arthritis among PsA patients in dermatologist's office. Dermatologists should screen for PsA in their patients, especially those with risk characteristics and early signs.

MicroRNA in Osteoarthritis

Osteoarthritis (OA) is the most prevalent degenerative joint disease and is accompanied by pain and joint dysfunction. Its clinical treatment tends to be unsatisfactory. Novel targets in OA include genes that are involved in OA pathophysiology and have been discovered using gene network, epigenetic and microRNA (miRNA) approaches. miRNA has been implicated in important cellular processes such as lipid metabolism, apoptosis, differentiation and organ development. The importance of miRNA regulation in cellular function is becoming increasingly clear as new miRNA targets are revealed. The present review summarizes the current evidence of the important role played by miRNA in determining the complex gene expression patterns of OA chondrocytes and their role in the regulation of transcription, and possible demethylation mechanisms that might be applicable in OA. In summary, miRNA may have important diagnostic and therapeutic potential, and might provide a novel means of treating OA.

Abstract P4-02-06: Beyond CYP2D6 Genotyping: Personalized Dosing of Tamoxifen (Tam) Based on Low Serum Endoxifen Levels

Background: The efficacy of Tam varies widely. Tam is biotransformed to endoxifen and 4-OH-Tam by the cytochrome P450 2D6 enzymes. Studies on 2D6 variants as a predictor of Tam's efficacy show conflicting results. Compared to Tam, endoxifen and 4-OH-Tam have a 100-fold greater affinity for the estrogen receptor (ER) and in suppressing estrogen-dependent cell proliferation. However, endoxifen is present at concentrations up to 20-fold higher and is pharmacologically distinct from 4-OH-Tam. Endoxifen's effect on ERα-degredation and transcription is concentration dependent; serum endoxifen levels ≥40nM block ERα-mediated transcriptional activation and inhibit estrogen-induced breast cancer cell proliferation.

Methods: Pts taking Tam 20 mg/day, for any reason, were potentially eligible. Serum Tam, Tam metabolites and nineteen 2D6 alleles were analyzed. 2D6 genotyping was performed by PCR-based procedures and metabolites were assessed on Liquid Chromatography/Tandem Mass Spectrometry. Pts were stratified by 2D6 function into 3 groups: extensive metabolizers (EM) who had normal enzyme activity; intermediate metabolizers (IM) who had reduced enzyme activity; and poor metabolizers (PM) who had no enzyme activity. Tam was increased to 30 mg/day if serum endoxifen < 40nMol. Serum Tam and Tam metabolites were measured every 2 weeks for 90 days.

Results: 121 patients have enrolled to date. Age, ethnicity, BMI, concomitant medications, and adherence were recorded. 25/117 (21%) pts had low serum endoxifen; all of these pts were increased to Tam 30 mg/day. Of this cohort, 36% were PMs (PM/PM and PM/IM), 32% were IMs (EM/PM and IM/IM) and 32% were EMs (EM/EM and EM/IM). All patients’ serum endoxifen increased to >40nMol by day 30 (Diagram below).

Conclusions: 1) Sub-therapeutic serum endoxifen can be found in any 2D6 phenotype. 2) It is possible to achieve therapeutic serum endoxifen/Tam metabolite levels by optimizing the dose of Tam. 3) Subsequently, it is likely that other gene variants are involved in Tam metabolism hence why 2D6 testing may lead to conflicting results. 4). Further investigation is warranted as personalizing the dose of Tam is feasible and may potentially improve the outcome of pts taking Tam regardless of 2D6 genotype. Figure available in online version.

Meta-analysis of the association between anti-HBc seropositivity and a poor prognosis of chronic HCV infection

AIM

  The impact of serological HBsAg- and anti-HBc+ on the prognosis of chronic hepatitis C virus (HCV) infection is unknown. We conducted a systematic review to analyze whether anti-HBc positivity imposes any effect on the course of HCV-related chronic liver disease.

METHODS

  We retrieved references from online databases that included PubMed and EMBASE. Data were gathered with regard to demographic information, disease progression and prognosis, and the results of serological tests. The development of hepatocellular carcinoma (HCC) was the endpoint of follow-up of all cohort studies.

RESULTS

  Eighteen references were included in this study, of which four were cohort studies. Twelve studies were retrospective, observational and non-interventional studies. According to our meta-analysis, the rate of serological HBsAg- and anti-HBc+ was higher among HCC patients compared with non-HCC patients (odds ratio [OR], 1.55; 95% CI, 1.22-1.98). HCV patients that were anti-HBc+ had a greater chance of developing HCC than their anti-HBc- counterparts (OR, 2.15; 95% CI, 1.34-3.47).

CONCLUSIONS

  The serological status of HBsAg- and anti-HBc+ appears to be correlated with a poor prognosis for chronic HCV infection. Though the general quality of these references was low, and multiple confounding factors existed, the likelihood of a poorer outcome of HCV patients that are positive for anti-HBc should be considered by their physicians.

Utilizing spiral computerized tomography during the removal of a fractured endodontic instrument lying beyond the apical foramen

AIM

To present a case that used spiral computerized tomography (CT) to locate and successfully remove a fractured endodontic instrument lying beyond the apical foramen using a surgical approach.

SUMMARY

The fracture of an endodontic instrument beyond the apical foramen is rare. In this case report, after an attempt to remove a fractured instrument failed, a multi-slice spiral computerized tomography (MSCT) was used for diagnosis and treatment planning. The fractured segment was precisely located and found in the soft tissue and successfully removed by surgery. For the successful removal of a fractured endodontic instrument beyond the apical foramen, the following are necessary: (i) knowledge of the cause of fracture and how to plan treatment; (ii) determining the precise location of the fractured segment using CT; and 3) skilful operation.

KEY LEARNING POINTS

•  Fractured endodontic instruments might lie within the soft tissue. •  Computerized tomography is an effective diagnostic aid for localizing the precise position of fractured instruments.

Association of angiotensin-converting enzyme inhibitor-associated angioedema with transplant and immunosuppressant use

BACKGROUND

Immunosuppressants decrease circulating dipeptidyl peptidase IV (DPPIV) activity in transplant patients, and decreased DPPIV activity has been associated with angiotensin-converting enzyme (ACE) inhibitor-associated angioedema. One study has reported an increased incidence of ACE inhibitor-associated angioedema among transplant patients compared to published rates, while several case series report angioedema in patients taking specific immunosuppressant agents.

OBJECTIVE

To test the hypothesis that transplant patients are at increased risk of ACE inhibitor-associated angioedema.

METHODS

We assessed the proportion of transplant patients in 145 cases with ACE inhibitor-associated angioedema and 280 ACE inhibitor-exposed controls. We measured the relationship between case-control status, transplant status, and immunosuppressant use and circulating DPPIV activity. We also assessed the incidence of angioedema among consecutive patients who underwent renal or cardiac transplant and were treated with an ACE inhibitor.

RESULTS

Transplant patients were significantly overrepresented among ACE inhibitor-associated angioedema cases compared to controls (odds ratio 18.5, 95% CI 2.3-147.2, P = 0.0004). Immunosuppressant use, chronic renal failure, seasonal allergies and smoking were also associated with ACE inhibitor-associated angioedema in univariate analysis. The association of transplant status with ACE inhibitor-associated angioedema was no longer significant after inclusion of immunosuppressant therapy in a multivariate analysis. Dipeptidyl peptidase IV activity was significantly decreased in sera from cases compared to ACE inhibitor-exposed controls, as well as in individuals taking immunosuppressants. Two of 47 ACE inhibitor-treated renal transplant patients and one of 36 ACE inhibitor-treated cardiac transplant patients developed angioedema.

CONCLUSION

Transplant patients are at increased risk of ACE inhibitor-associated angioedema possibly because of the effects of immunosuppressants on the activity of DPPIV.

The NMR solution structure of human epidermal growth factor (hEGF) at physiological pH and its interactions with suramin

Human epidermal growth factor (hEGF) induces the proliferation, differentiation and survival of various cell types including tumor-derived cells. Generally, hEGF performs its biological function by binding to a specific receptor (hEGFR) on the cell surface, thereby inducing signal transduction. Suramin, a polysulfonated naphthylurea that acts as a growth factor blocker, exhibits antiproliferative activity against non-small cell lung cancer (NSCLC) cells that overexpress EGFR on the cell surface. We determined the solution structure of hEGF under physiological conditions and investigated the interaction of suramin with hEGF using isothermal titration calorimetry and NMR spectroscopy techniques. The solution structure of hEGF presented in this paper is different from the bound form of hEGF present in the crystal structure of the 2:2 EGF-EGFR complex because its C-tail contains a hydrophobic core. This conformational difference supports the hypothesis that hEGF undergoes a conformational change when it binds to hEGFR and subsequently induces signal transduction. Based on the docking structure of the hEGF-suramin complex, we demonstrated how suramin blocks hEGF by binding to its receptor binding site (the C-terminal region around Arg45) and inhibits the crucial conformational change.