Multinational data on cumulative radiation exposure of patients from recurrent radiological procedures: call for action

European Radiology - To have a global picture of the recurrent use of CT imaging to a level where cumulative effective dose (CED) to individual patients may be exceeding 100 mSv at which organ...     

The inferior frontal gyrus and phonological processing: an investigation using rTMS

Repetitive transcranial magnetic stimulation (rTMS) offers a powerful new technique for investigating the distinct contributions of the cortical language areas. We have used this method to examine the role of the left inferior frontal gyrus (IFG) in phonological processing and verbal working memory. Functional neuroimaging studies have implicated the posterior part of the left IFG in both phonological decision making and subvocal rehearsal mechanisms, but imaging is a correlational method and it is therefore necessary to determine whether this region is essential for such processes. In this paper we present the results of two experiments in which rTMS was applied over the frontal operculum while subjects performed a delayed phonological matching task. We compared the effects of disrupting this area either during the delay (memory) phase or at the response (decision) phase of the task. Delivered at a time when subjects were required to remember the sound of a visually presented word, rTMS impaired the accuracy with which they subsequently performed the task. However, when delivered later in the trial, as the subjects compared the remembered word with a given pseudoword, rTMS did not impair accuracy. Performance by the same subjects on a control task that required the processing of nonverbal visual stimuli was unaffected by the rTMS. Similarly, performance on both tasks was unaffected by rTMS delivered over a more anterior site (pars triangularis). We conclude that the opercular region of the IFG is necessary for the normal operation of phonologically based working memory mechanisms. Furthermore, this study shows that rTMS can shed further light on the precise role of cortical language areas in humans.     

Antiangiogenic Therapy in Colorectal Cancer: Where Are We 5 Years Later?

The past 5 years mark a watershed period in the treatment of patients with colorectal cancer (CRC). During this time, results from several clinical trials proved that targeting tumor-mediated angiogenesis improves overall survival for patients with metastatic CRC (mCRC) when used in combination with first-line and second-line chemotherapy regimens, data that do not simply serve as “proof of principle” for antiangiogenic therapy but that will drive much of the research agenda in CRC for the coming years. Despite the demonstrated gains in survival when antiangiogenic therapy is used for patients with metastatic disease, however, results from the first trial to test the addition of bevacizumab to adjuvant chemotherapy have been disappointing. The expense of agents in the targeted therapy category has been the cause of much discussion on their appropriate use and puts particular emphasis on the need for suitable markers that will allow for the appropriate selection of patients. Although antiangiogenic therapy has demonstrated clear benefit in the treatment of patients with mCRC, limitations in efficacy, duration of therapy, role of maintenance therapy, potential toxicities, and predictive markers for optimal patient selection are subjects of ongoing research. Herein, we present a review of the recent advances in antiangiogenic therapy in CRC and provide insights into several promising upcoming studies.     

Origin of INSL3-mediated testicular descent in therian mammals

Testicular descent is a unique physiological adaptation found in therian mammals allowing optimal spermatogenesis below core body temperature. Recent studies show that INSL3, produced by Leydig cells, and its receptor LGR8 (RXFP2) are essential for mediating the transabdominal phase of testicular descent during early development. However, the origin and genetic basis for this physiological adaptation is not clear. Using syntenic mapping and the functional characterization of contemporary and resurrected relaxin family hormones, we show that derivation of INSL3-mediated testicular descent involved the duplication of an ancestral RLN3-like gene that encodes an indiscriminate ligand for LGR7 (RXFP1) and LGR8. This event was followed by acquisition of the LGR7-selective characteristics by a daughter gene (RLN3) prior to the evolution of the common ancestor of monotremes, marsupials, and placentals. A subsequent mutation of the other daughter gene (INSL3) occurred before the emergence of therian mammals, which then led to the derivation of the reciprocal LGR8-specific characteristics of INSL3. The stepwise evolution of these independent signaling pathways through gene duplication and subsequent divergence is consistent with Darwinian theory of selection and adaptation, and the temporal proximity suggests an association between these genetic events and the concurrent evolution of testicular descent in ancestral therian mammals.     

Microleakage in Class II composite restorations with margins below the CEJ: In vitro evaluation of different restorative techniques

Objectives: The purpose of this in vitro study was to evaluate the microleakage in “deep” Class II composite restorations with gingival cavosurface margin below the CEJ (cemento-enamel junction) and restored with different techniques. Study Design: Fifty human teeth were used. In each tooth two standardized Class II slot cavities (on mesial and on distal surfaces) were prepared: the buccolingual extension of the cavities was 4 mm; the gingival wall was located in dentin/cementum (2 mm beyond the CEJ). The prepared teeth were randomly assigned to 5 experimental groups (of 10 specimens and 20 cavities each) and restored. Group 1: Filtek TM Supreme XTE Flowable (3MESPE) + Universal Filtek Supreme XTE (3MESPE), Group 2: GrandioSO Heavy Flow (Voco) + GrandioSo (Voco), Group 3: SDR™ (Dentsply Caulk) + Esthet-X® HD (Dentsply Caulk), Group 4: SonicFill (Kerr), Group 5: Grandio (Voco). After thermocycling, the specimens were immersed in a 0.5% basic fuchsine dye solution and incubated at 37°C for 24 hours. The teeth were subsequently sectioned mesiodistally. All specimens were examined at 25× in a stereomicroscope and standardized digital images were obtained. Dye penetration was measured from gingival margins. Results: The results demonstrated no significant leakage differences between Group 4 and Group 5, that both showed significantly higher frequency distribution of Score 0. Group 2 and Group 3 showed a significant prevalence of Score 1, whereas Group 1 showed significantly higher frequency of Score 2. Conclusions: None of the restorative techniques tested completely eliminated microleakage dye penetration in dentin margins; marginal adaptation in Class II composite restorations with gingival wall below the CEJ varied in both substrates and from different restorative techniques used. Key words:Microleakage, Class II composite restorations, CEJ.     

IAEA survey of paediatric computed tomography practice in 40 countries in Asia, Europe, Latin America and Africa: procedures and protocols

Objective

To survey procedures and protocols in paediatric computed tomography (CT) in 40 less resourced countries.

Methods

Under a project of the International Atomic Energy Agency, 146 CT facilities in 40 countries of Africa, Asia, Europe and Latin America responded to an electronic survey of CT technology, exposure parameters, CT protocols and doses.

Results

Modern MDCT systems are available in 77 % of the facilities surveyed with dedicated paediatric CT protocols available in 94 %. However, protocols for some age groups were unavailable in around 50 % of the facilities surveyed. Indication-based protocols were used in 57 % of facilities. Estimates of radiation dose using CTDI or DLP from standard CT protocols demonstrated wide variation up to a factor of 100. CTDI_vol values for the head and chest were between two and five times those for an adult at some sites. Sedation and use of shielding were frequently reported; immobilisation was not. Records of exposure factors were kept at 49 % of sites.

Conclusion

There is significant potential for improvement in CT practice and protocol use for children in less resourced countries. Dose estimates for young children varied widely. This survey provides critical baseline data for ongoing quality improvement efforts by the IAEA.

Key Points

? Paediatric computed tomography (CT) practice was audited in 40 less resourced countries. ? This audit revealed widespread (up to 100 times) variation in radiation dose. ? Specific CT protocols for certain age groups were frequently (ca. 50 %) unavailable. ? This survey demonstrates significant potential for improvement in paediatric CT practice. ? Multinational networking is an effective mechanism for quality improvement.     

Convolutional neural networks for high throughput screening of catalyst layer inks for polymer electrolyte fuel cells

The performance of polymer electrolyte fuel cells decisively depends on the structure and processes in membrane electrode assemblies and their components, particularly the catalyst layers. The structural building blocks of catalyst layers are formed during the processing and application of catalyst inks. Accelerating the structural characterization at the ink stage is thus crucial to expedite further advances in catalyst layer design and fabrication. In this context, deep learning algorithms based on deep convolutional neural networks (ConvNets) can automate the processing of the complex and multi-scale structural features of ink imaging data. This article presents the first application of ConvNets for the high throughput screening of transmission electron microscopy images at the ink stage. Results indicate the importance of model pre-training and data augmentation that works on multiple scales in training robust and accurate classification pipelines.

Deep learning enables the robust and accurate classification of the TEM images of catalyst layer inks for the polymer electrolyte fuel cells.