Persistence of DNMT3A mutations at long‐term remission in adult patients with AML

Mutations in DNMT3A, the gene encoding DNA methyltransferase 3 alpha, have been identified as molecular drivers in acute myeloid leukaemia (AML) with possible implications for minimal residual disease monitoring and prognosis. To further explore the utility of DNMT3A mutations as biomarkers for AML, we developed assays for sensitive detection of recurrent mutations affecting residue R882. Analysis of DNA from 298 diagnostic AML samples revealed DNMT3A mutations in 45 cases (15%), which coincided with mutations in NPM1, FLT3 and IDH1. DNMT3A mutations were stable in 12 of 13 patients presenting with relapse or secondary myelodysplastic syndrome, but were also present in remission samples from 14 patients (at allele frequencies of <1–50%) up to 8 years after initial AML diagnosis, despite the loss of all other molecular AML markers. The mutant DNMT3A allele burden was not related to the clinical course of disease. Cell sorting demonstrated the presence of DNMT3A mutations in leukaemic blasts, but also at lower allele frequencies in T and B‐cells from the same patients. Our data are consistent with the recent finding of preleukaemic stem cells in AML, which are resistant to chemotherapy. The persistence of DNMT3A mutations during remission may have important implications for the management of AML.     

Addition of zinc methacrylate in dental polymers: MMP-2 inhibition and ultimate tensile strength evaluation

This study evaluated the effect of zinc methacrylate (ZM) on the inhibition of matrix metalloproteinase 2 (MMP-2) and the ultimate tensile strength (UTS) of an experimental polymer. Enzymes secreted from mouse gingival tissues were analyzed by gelatin zymography in buffers containing 5 mM CaCl₂ (Tris–CaCl₂) in 50 mM Tris–HCl buffer with various concentrations of ZM (0.5, 1, 2, 4, 8, and 16 mM). The matrix metalloproteinases present in the conditioned media were characterized by immunoprecipitation. The polymer UTS evaluation was performed in eight groups with various concentrations of ZM (0, 0.5, 1, 2.5, 5, 10, 20, and 30 wt.%), in a mechanical testing machine. MMP-2 (62 kDa) was detected in the zymographic assays and inhibited by ZM in all tested concentrations. UTS data were submitted to one-way ANOVA and Tukey's test (α = 0.05), and no significant differences were observed among groups, except in the polymer containing 30% ZM, presenting a significantly lower value when compared with the control group (p < 0.05). The results suggest that ZM inhibits MMP-2 expression in all concentrations tested, while small concentrations did not affect the ultimate tensile strength of the polymer. Zinc methacrylate is a metalloproteinase inhibitor that can be copolymerized with other methacrylate monomers. Yet, the addition of ZM did not affect the resin bond strength. Thus, in vivo tests should be performed to evaluate the performance of this material.     

Genetic analysis of the IL8 gene polymorphism (rs4073) in generalized aggressive periodontitis

ObjectivesInterleukin (IL)-8 is an important chemokine for regulation of the inflammatory response. A single nucleotide polymorphism (SNP) reference sequence (rs) 4073 in the IL8 gene has been shown to regulate IL-8 levels after stimulation with lipopolysaccharide. This study investigates the transmission pattern of the IL8 rs4073 risk allele A and its association with susceptibility to aggressive periodontitis (AgP) in families and in a case–control cohort of unrelated individuals from a Brazilian population.DesignGenotyping was performed by standard polymerase chain reaction-restriction fragment length polymorphism assay (PCR-RFLP) in 13 nuclear families and 184 unrelated subjects. Statistical analysis was performed using the transmission disequilibrium test (TDT) for the family dataset and Chi-square test and multivariate logistic regression modelling for the case–control dataset.ResultsTDT analyses did not detect evidence of over transmission of IL8 rs4073 alleles in affected and unaffected family members (allele T: 52%; allele A: 48%; p = 0.2252). How expected, analyses of cases and unrelated controls showed a significant and inverse association of age with AgP; however, a lack of association between genotypes, ethnic groups and generalized AgP was observed.ConclusionsThe SNP (rs4073) was not associated with AgP in unrelated individuals and there is no evidence of over transmission of the alleles in families with AgP, from Brazilian individuals.     

Pathogen-driven decision for implant retention in the management of infected total knee prostheses

Purpose

In prosthetic joint infections (PJIs) of the knee, debridement with implant retention is associated with a high risk of recurrence.

Methods

A single-centre cohort study was performed with extensive analysis of the literature covering 1980–2012.

Results

In 21 patients (mean age 80.4 years, 19 immunosuppressed), in association with 1.5–three months of antibiotic treatment, an attempt was made to salvage the prosthesis by open (11 patients) or arthroscopic (ten patients) debridement. After a mean follow-up of seven years (range four–20 years), patients were in remission in seven cases (33 %). Remission was achieved in 0 % of all methicillin-resistant Staphylococcus aureus (MRSA) infections (zero/three), in 0 % (zero/three) of methicillin-resistant coagulase-negative staphylococcal infections, in 29 % (two/seven) of methicillin-sensitive S. aureus infections and in 75 % (three/four) of infections due to streptococci. The literature review focused on implant preserving approaches yielded 599 cases with an overall success rate of 47 % (284/599) and significantly more remissions in streptococcal vs staphylococcal knee PJIs (43/54 vs 144/324; p < 0.01, odds ratio 4.9, 95 % confidence interval 2.4–10.9).

Conclusions

In addition to established indications for explantation such as implant loosening, sinus tract or methicillin resistance, the decision for debridement and retention of knee PJIs should also depend on the pathogen. Implant preservation is futile with methicillin-resistant staphylococci, but seems to be a valid option for streptococcal PJIs.     

Standardization of the Prosody in Use Battery (PUB): a speech prosody perception test in Danish

Assessment of prosody perception may be useful in a number of clinical scenarios, including the rehabilitation of cochlear implant recipients. It is with this group in mind that we have derived and standardized a battery of tests that assess speech prosody perception in the Danish language. The prosodic contrasts included in the battery are vowel length, compounds and phrases, emotions, questions and statements, prominence and pronoun reference, all of which are commonly encountered in everyday communication. Lists of candidate stimuli were compiled and recorded by a representative speaker of Danish. All candidate stimuli were presented to normal hearing subjects (n = 12) in both unprocessed and 8-channel noise vocoded conditions. Subjects performed closed-set identification and the results were used to derive the final stimulus set. We report the results of the six subtests, in which we observed a bias to compounds in the compound/phrase subtest, and to statements in question/statement subtest. The pronoun reference subtest assessed the ability of a listener to infer a referent from the stress status of a pronoun, and we found high accuracy rates on this task indicating that it is suitable for inclusion in the battery. We discuss the possible uses of the Prosody in Use Battery in cochlear implant mapping and device verification. We also consider the role of the results from the test battery in guiding clinicians to material suitable for aural rehabilitation.     

ASSOCIATION BETWEEN POLYMORPHISM IN THE PROMOTER REGION (G/C-915) OF PAX9 GENE AND THIRD MOLAR AGENESIS

Purpose:

Hypodontia is the congenital absence of one or more (up to six) permanent and/or deciduous teeth, being one of the most common alterations of the human dentition. Genetic polymorphisms are variations of DNA sequences occurring in a population. This study investigated whether G-915C single nucleotide polymorphism (SNPs) in the PAX9 gene promoter is associated with hypodontia in humans.

Material and Methods:

The polymorphism in region G/C-915 of PAX9 gene (NCBI ref SNP ID: rs 2073247) of 240 patients was analyzed, being 110 controls and 130 individuals with third molar agenesis. After DNA extraction, the region of interest was amplified by PCR technique using two different primers. The significance of the differences in observed frequencies of polymorphisms in both groups was assessed by odds-ratio and chi-squared test with 95% confidence interval.

Results:

Genotype CC was more frequent in patients with agenesis (11.5%) compared to the control (1.8%), while GG was more prevalent in the control group (39.1%) compared to the individuals with agenesis (26.2%).

Conclusion:

These data showed that the allele C could be associated with the third molar agenesis.     

Accumulation of lipids and oxidatively damaged DNA in hepatocytes exposed to particles

Exposure to particles has been suggested to generate hepatosteatosis by oxidative stress mechanisms. We investigated lipid accumulation in cultured human hepatocytes (HepG2) and rat liver after exposure to four different carbon-based particles. HepG2 cells were exposed to particles for 3 h and subsequently incubated for another 18 h to manifest lipid accumulation. In an animal model of metabolic syndrome we investigated the association between intake of carbon black (CB, 14 nm) particles and hepatic lipid accumulation, inflammation and gene expression of Srebp-1, Fasn and Scd-1 involved in lipid synthesis. There was a concentration-dependent increase in intracellular lipid content after exposure to CB in HepG2 cells, which was only observed after co-exposure to oleic/palmitic acid. Similar results were observed in HepG2 cells after exposure to diesel exhaust particles, fullerenes C₆₀ or pristine single-walled carbon nanotubes. All four types of particles also generated oxidatively damaged DNA, assessed as formamidopyrimidine DNA glycosylase (FPG) sensitive sites, in HepG2 cells after 3 h exposure. The animal model of metabolic syndrome showed increased lipid load in the liver after one oral exposure to 6.4 mg/kg of CB in lean Zucker rats. This was not associated with increased iNOS staining in the liver, indicating that the oral CB exposure was associated with hepatic steatosis rather than steatohepatitis. The lipid accumulation did not seem to be related to increased lipogenesis because there were unaltered gene expression levels in both the HepG2 cells and rat livers. Collectively, exposure to particles is associated with oxidative stress and steatosis in hepatocytes.     

Chronic exposure to low concentrations of strontium 90 affects bone physiology but not the hematopoietic system in mice

The aim of this work was to delineate the effects of chronic ingestion of strontium 90 (⁹⁰Sr) at low concentrations on the hematopoiesis and the bone physiology. A mouse model was used for that purpose. Parent animals ingested water containing 20 kBq l^?1 of ⁹⁰Sr two weeks before mating. Offspring were then continuously contaminated with ⁹⁰Sr through placental transfer during fetal life, through lactation after birth and through drinking water after weaning. At various ages between birth and 20 weeks, animals were tested for hematopoietic parameters such as blood cell counts, colony forming cells in spleen and bone marrow and cytokine concentrations in the plasma. However, we did not find any modification in ⁹⁰Sr ingesting animals as compared with control animals. By contrast, the analysis of bone physiology showed a modification of gene expression towards bone resorption. This was confirmed by an increase in C‐telopeptide of collagen in the plasma of ⁹⁰Sr ingesting animals as compared with control animals. This modification in bone metabolism was not linked to a modification of the phosphocalcic homeostasis, as measured by calcium, phosphorus, vitamin D and parathyroid hormone in the blood. Overall these results suggest that the chronic ingestion of ⁹⁰Sr at low concentration in the long term may induce modifications in bone metabolism but not in hematopoiesis. Copyright © 2012 John Wiley & Sons, Ltd.