An adaptation strategy to urban heat: hospital rooms with radiant cooling accelerate patient recovery

Background

Patients with respiratory diseases are vulnerable to the effects of heat. Therefore, it is important to develop adaptation strategies for heat exposure. One option is to optimise the indoor environment. To this end, we equipped hospital patient rooms with radiant cooling. We performed a prospective randomised clinical trial to investigate potentially beneficial effects of the hospitalisation in rooms with radiant cooling on patients with a respiratory disease exacerbation.

Methods

Recruitment took place in June, July and August 2014 to 2016 in the Charité – Universitätsmedizin Berlin, Germany. We included patients with COPD, asthma, pulmonary hypertension, interstitial lung disease and pneumonia. 62 patients were allocated to either a standard patient room without air conditioning or a room with radiant cooling set to 23°C (73°F). We analysed the patients’ length of stay with a Poisson regression. Physiological parameters, fluid intake and daily step counts were tested with mixed regression models.

Results

Patients hospitalised in a room with radiant cooling were discharged earlier than patients in standard rooms (p=0.003). The study participants in chambers with radiant cooling had a lower body temperature (p=0.002), lower daily fluid intake (p<0.001), higher systolic blood pressure (p<0.001) and an increased daily step count (p<0.001).

Conclusion

The results indicate that a radiant cooling system in hospital patient rooms provides clinical benefits for patients with respiratory disease exacerbations during the warm summer months, which may contribute to an earlier mobilisation. Radiant cooling is commended as a suitable adaptation strategy to reduce the clinical impact of climate warming.

A radiant cooling system in hospital patient rooms provides clinical benefits for patients with respiratory disease exacerbations during summertime. Patients hospitalised in rooms with air convection free radiant cooling are discharged earlier.https://bit.ly/3p9Fkqm

Strain induced mechanoresponse depends on cell contractility and BAG3-mediated autophagy

Basically all mammalian tissues are constantly exposed to a variety of environmental mechanical signals. Depending on the signal strength, mechanics intervenes in a multitude of cellular processes and is thus capable to induce simple cellular adaptations but also complex differentiation processes and even apoptosis. The underlying recognition typically depends on mechanosensitive proteins, which most often sense the mechanical signal for the induction of a cellular signaling cascade by changing their protein conformation. However, the fate of mechanosensors after mechanical stress application is still poorly understood and it remains unclear whether protein degradation pathways affect the mechanosensitivity of cells. Here, we show that cyclic stretch induces autophagosome formation in a time-dependent manner. Formation depends on the cochaperone BAG3 and thus likely involves BAG3-mediated chaperone-assisted selective autophagy. Furthermore, we demonstrate that strain-induced cell reorientation is clearly delayed upon inhibition of autophagy, suggesting a bidirectional crosstalk between mechanotransduction and autophagic degradation. The strength of the observed delay depends on stable adhesion structures and stress fiber formation in a RhoA-dependent manner.

Real-world implementation of video-observed therapy in an urban TB program in the United States

BACKGROUND:

Video directly observed therapy (vDOT) was introduced to increase flexibility and meet patient-specific needs for TB treatment. This study aimed to assess the reach and effectiveness of vDOT for TB treatment under routine conditions in Alameda County, CA, USA, a busy, urban setting, from 2018 to 2020.

METHODS:

We prospectively evaluated routinely collected data to estimate 1) reach (proportion of patients initiated on vDOT vs. in-person DOT); and 2) effectiveness (proportion of prescribed doses with verified administration by vDOT vs. in-person DOT).

RESULTS:

Among 163 TB patients, 94 (58%) utilized vDOT during treatment, of whom 54 (57%) received exclusively vDOT. Individuals receiving vDOT were on average younger than those receiving in-person therapy (46 vs. 61 years; P < 0.001). The median time to vDOT initiation was 2.2 weeks (IQR 1.1–10.0); patients were monitored for a median of 27.0 weeks (IQR 24.6–31.9). vDOT led to higher proportions of verified prescribed doses than in-person DOT (68% vs. 54%; P < 0.001). Unobserved self-administration occurred for all patients on weekends based on clinic instructions, but a larger proportion of doses were self-administered during periods of in-person DOT than of vDOT (45% vs. 24%; P < 0.001).

CONCLUSION:

A TB program successfully maintained vDOT, reaching the majority of patients and achieving greater medication verification than in-person DOT.

Prognostic value of tumor mutational burden in patients with oral cavity squamous cell carcinoma treated with upfront surgery

Background

Oral cavity is the most prevalent site of head and neck squamous cell carcinomas (HNSCCs). Most often diagnosed at a locally advanced stage, treatment is multimodal with surgery as the cornerstone. The aim of this study was to explore the molecular landscape of a homogenous cohort of oral cavity squamous cell carcinomas (OCSCCs), and to assess the prognostic value of tumor mutational burden (TMB), along with classical molecular and clinical parameters.

Patients and methods

One hundred and fifty-one consecutive patients with OCSCC treated with upfront surgery at the Institut Curie were analyzed. Sequencing of tumor DNA from frozen specimens was carried out using an in-house targeted next-generation sequencing panel (571 genes). The impact of molecular alterations and TMB on disease-free survival (DFS) and overall survival (OS) was evaluated in univariate and multivariate analyses.

Results

Pathological tumor stage, extranodal spread, vascular emboli, and perineural invasion were associated with both DFS and OS. TP53 was the most mutated gene (71%). Other frequent molecular alterations included the TERT promoter (50%), CDKN2A (25%), FAT1 (17%), PIK3CA (14%), and NOTCH1 (15%) genes. Transforming growth factor-β pathway alterations (4%) were associated with poor OS (P = 0.01) and DFS (P = 0.02) in univariate and multivariate analyses. High TMB was associated with prolonged OS (P = 0.01 and P = 0.02, in the highest 10% and 20% TMB values, respectively), but not with DFS. Correlation of TMB with OS remained significant in multivariate analysis (P = 0.01 and P = 0.005 in the highest 10% and 20% TMB values, respectively). Pathological tumor stage combined with high TMB was associated with good prognosis.

Conclusion

Our results suggest that a high TMB is associated with a favorable prognosis in patients with OCSCC treated with upfront surgery.

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High TMB is associated with a favorable prognosis in patients with OCSCC treated with upfront surgery

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Pathological tumor stage combined with high TMB is associated with good prognosis

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TP53 was the most mutated gene (71%). Other frequent molecular alterations included the TERT promoter (50%)

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TGFβ pathway alterations were associated with poor outcomes, although it was only observed in 4% of the patients

Cyclically stretched ACL fibroblasts emigrating from spheroids adapt their cytoskeleton and ligament-related expression profile

Mechanical stress of ligaments varies; hence, ligament fibroblasts must adapt their expression profile to novel mechanomilieus to ensure tissue resilience. Activation of the mechanoreceptors leads to a specific signal transduction, the so-called mechanotransduction. However, with regard to their natural three-dimensional (3D) microenvironment cell reaction to mechanical stimuli during emigrating from a 3D spheroid culture is still unclear. This study aims to provide a deeper understanding of the reaction profile of anterior cruciate ligament (ACL)-derived fibroblasts exposed to cyclic uniaxial strain in two-dimensional (2D) monolayer culture and during emigration from 3D spheroids with respect to cell survival, cell and cytoskeletal orientation, distribution, and expression profile. Monolayers and spheroids were cultured in crosslinked polydimethyl siloxane (PDMS) elastomeric chambers and uniaxially stretched (14% at 0.3 Hz) for 48 h. Cell vitality, their distribution, nuclear shape, stress fiber orientation, focal adhesions, proliferation, expression of ECM components such as sulfated glycosaminoglycans, collagen type I, decorin, tenascin C and cell-cell communication-related gap junctional connexin (CXN) 43, tendon-related markers Mohawk and tenomodulin (myodulin) were analyzed. In contrast to unstretched cells, stretched fibroblasts showed elongation of stress fibers, cell and cytoskeletal alignment perpendicular to strain direction, less rounded cell nuclei, increased numbers of focal adhesions, proliferation, amplified CXN43, and main ECM component expression in both cultures. The applied cyclic stretch protocol evoked an anabolic response and enhanced tendon-related marker expression in ACL-derived fibroblasts emigrating from 3D spheroids and seems also promising to support in future tissue formation in ACL scaffolds seeded in vitro with spheroids.

Efficacy of Retreatment After Failed Direct-acting Antiviral Therapy in Patients With HCV Genotype 1-3 Infections

Hepatitis C virus infection is causing chronic liver disease, cirrhosis, and hepatocellular carcinoma. By combining direct-acting antivirals (DAAs), high sustained virologic response rates (SVRs) can be achieved. Resistance-associated substitutions (RASs) are commonly observed after DAA failure, and especially nonstructural protein 5A (NS5A) RASs may impact retreatment options.^1-3 Data on retreatment of DAA failure patients using first-generation DAAs are limited.^4-7 Recently, a second-generation protease- and NS5A-inhibitor plus sofosbuvir (voxilaprevir/velpatasvir/sofosbuvir [VOX/VEL/SOF]) was approved for retreatment after DAA failure.⁸ However, this and other second-generation regimens are not available in many resource-limited countries or are not reimbursed by regular insurance, and recommendations regarding the selection of retreatment regimens using first-generation DAAs are very important. This study aimed to analyze patients who were re-treated with first-generation DAAs after failure of a DAA combination therapy.

A systematic review and in-depth analysis of outcome reporting in early phase studies of colorectal cancer surgical innovation

AIM

Early phase studies are essential to evaluate new technologies prior to randomized evaluation. Evaluation is limited, however, by inconsistent measurement and reporting of outcomes. This study examines outcome reporting in studies of innovative colorectal cancer surgery.

METHODS

Systematic searches identified studies of invasive procedures treating primary colorectal adenocarcinoma. Included were a random sample of studies which authors reported as 'new' or 'modified'. Outcomes were extracted verbatim and categorized using an existing framework of 32 domains relevant to early phase studies. Outcomes were classified as 'measured' (where there was an explicit statement to that effect or evidence that data collection had occurred) or 'mentioned but not measured' (where outcomes were discussed but data collection was not evident). Patterns of identified outcomes are described.

RESULTS

Of 8373 records, 816 were potentially eligible. Full-text review of a random sample of 218 studies identified 51 for inclusion of which 34 (66%) were 'new' and 17 (33%) were 'modified'. Some 2073 outcomes were identified, and all mapped to domains. 'Anticipated disadvantages' were most frequently identified [660 (32%) outcomes identified across 50 (98%) studies]. No domain was represented in all studies. Under half (944, 46%) of outcomes were 'measured'. 'Surgeon's/operator's experience of the innovation' was more frequently 'mentioned but not measured' [207 (18%) outcomes across 46 (90%) studies] than 'measured' [17 (2%) outcomes, 11 (22%) studies].

CONCLUSION

There is outcome reporting heterogeneity in studies of early phase colorectal cancer surgery. The adoption of core outcome sets may help to resolve these inconsistencies and enable efficient evaluation of surgical innovations.

Substrate Elasticity Exerts Functional Effects on Primary Microglia

Microglia-the brain's primary immune cells-exert a tightly regulated cascade of pro- and anti-inflammatory effects upon brain pathology, either promoting regeneration or neurodegeneration. Therefore, harnessing microglia emerges as a potential therapeutic concept in neurological research. Recent studies suggest that-besides being affected by chemokines and cytokines-various cell entities in the brain relevantly respond to the mechanical properties of their microenvironment. For example, we lately reported considerable effects of elasticity on neural stem cells, regarding quiescence and differentiation potential. However, the effects of elasticity on microglia remain to be explored.Under the hypothesis that the elasticity of the microenvironment affects key characteristics and functions of microglia, we established an in vitro model of primary rat microglia grown in a polydimethylsiloxane (PDMS) elastomer-based cell culture system. This way, we simulated the brain's physiological elasticity range and compared it to supraphysiological stiffer PDMS controls. We assessed functional parameters of microglia under "resting" conditions, as well as when polarized towards a pro-inflammatory phenotype (M1) by lipopolysaccharide (LPS), or an anti-inflammatory phenotype (M2) by interleukin-4 (IL-4). Microglia viability was unimpaired on soft substrates, but we found various significant effects with a more than two-fold increase in microglia proliferation on soft substrate elasticities mimicking the brain (relative to PDMS controls). Furthermore, soft substrates promoted the expression of the activation marker vimentin in microglia. Moreover, the M2-marker CD206 was upregulated in parallel to an increase in the secretion of Insulin-Like Growth Factor-1 (IGF-1). The upregulation of CD206 was abolished by blockage of stretch-dependent chloride channels. Our data suggest that the cultivation of microglia on substrates of brain-like elasticity promotes a basic anti-inflammatory activation state via stretch-dependent chloride channels. The results highlight the significance of the omnipresent but mostly overlooked mechanobiological effects exerted on microglia and contribute to a better understanding of the complex spatial and temporal interactions between microglia, neural stem cells, and glia, in health and disease.

Comparison between transthoracic echocardiography and transcranial Doppler for detection of PFO in patients in the acute phase of a pulmonary embolism. A Post-hoc analysis of EPIC-FOP

Introduction

Patent foramen ovale is a fairly common defect found in a quarter of the population. PFO has always been associated with an increased risk of stroke, the mechanism of which has been attributed to the paradoxical embolism of venous thrombi passing through the PFO directly into the left atrium, however this mechanism remains debated to date.

For the detection of PFO, several modalities exist including transcranial doppler (TCD), transthoracic echocardiography (TTE) and transoesophageal echocardiography. This raises the question of the examination with the best diagnostic performance for its detection.

Purpose

The majority of studies comparing the different modalities of patient PFO diagnosis have been conducted in the context of stroke assessment. Very few studies have focused on the acute PE patient population. The interest of our study is therefore to evaluate the diagnostic performance of two modalities (TTE versus TCD) for the detection of shunts, especially since this population is at risk of stroke by paradoxical embolism due to the phenomenon of hyperpressure in the right heart chambers increasing the chances of having a paradoxical embolism.

Methods

We performed a post HOC analysis of the EPIC-FOP study which is a multicenter, prospective, French cohort study. Patients were recruited within 3 days of diagnosis of PE. Patients included were given a transthoracic echocardiography (TTE) with PFO screening by injection of saline contrast and magnetic resonance imaging (MRI) within 7 days of inclusion to look for signs of recent stroke. A proportion of the patients included in this study also received a transcranial doppler in search of PFO, the results of which were used in our study.

Results

The mean age of the patients was 62±14.66 years with a slight male predominance (55.6%). TCD was able to detect 97 right-left shunts while the TTE detected only 25 shunts. Concordance analysis by Cohen's Kappa Coefficient: 0.1767 [0.0427; 0.3107–p&lt;0.001] is considered poor.

Using TTE as the reference examination, transcranial Doppler has a very good sensitivity 96.00% (79.65% to 99.90%) and a poor specificity 42.06% (33.33% to 51.18%). A good negative likelihood ratio 0.10 (0.01 to 0.66).

Using TCD, incidence of stroke in the acute phase of PE was significantly higher in the PFO population. In the ten strokes detected 9 had occurred in patients with PFO, RR=1.43 IC95% (1.1169 to 1.8228) p=0. 0044. The difference in proportion is calculated to be 26.92%.

Conclusion

It is the first study that compared TCD vs TEE in the setting of acute phase of PE for detection of PFO. TCD showed a good sensitivity and negative likelihood ratio that can be used as a first means to rule out PFO or associated with TTE. Also, our analysis confirms the increased risk of stroke following a PE episode when a PFO is present.

Funding Acknowledgement

Type of funding source: None

Outcome selection, measurement and reporting for new surgical procedures and devices: a systematic review of IDEAL/IDEAL-D studies to inform development of a core outcome set

BACKGROUND

Outcome selection, measurement and reporting for the evaluation of new surgical procedures and devices is inconsistent and lacks standardization. A core outcome set may promote the safe and transparent evaluation of surgical innovations. This systematic review examined outcome selection, measurement and reporting in studies conducted within the IDEAL (Idea, Development, Exploration, Assessment and Long-term monitoring) framework to examine current practice and inform the development of a core outcome set for early-phase studies of surgical procedures/devices.

METHODS

Web of Science and Scopus citation searches were performed to identify author-reported IDEAL/IDEAL-D studies for any surgical procedure/device. Outcomes were extracted verbatim, including contextual information regarding outcome selection and measurement. Outcomes were categorized to inform a conceptual framework of outcome domains relevant to evaluating innovation.

RESULTS

Some 48 studies were identified. Outcome selection, measurement and reporting varied widely across studies in different IDEAL stages. From 1737 outcomes extracted, 22 domains specific to evaluating innovation were conceptualized under seven broad categories: procedure completion success/failure; modifications; unanticipated events; surgeons' experiences; patients' experiences; resource use specific to the innovative procedure/device; and other innovation-specific outcomes. Most innovation-specific outcomes were measured and reported in only a small number of studies.

CONCLUSION

This review highlighted the need for guidance and standardization in outcome selection and reporting in the evaluation of new surgical procedures/devices. Novel outcome domains specific to innovation have been identified to establish a core outcome set for future evaluations of surgical innovations.

Immunomodulatory activity of β-glucan-containing exopolysaccharides from Auricularia auricular in phagocytes and mice infected with Cryptococcus neoformans

Current antifungal drugs present poor effectiveness and there is no available vaccine for fungal infections. Thus, novel strategies to treat or prevent invasive mycosis, such as cryptococcosis, are highly desirable. One strategy is the use of immunomodulators of polysaccharide nature isolated from mushrooms. The purpose of the present work was to evaluate the immunostimulatory activity of β-(1,3)-glucan-containing exopolysaccharides (EPS) from the edible mushrooms Auricularia auricula in phagocytes and mice infected with Cryptococcus neoformans. EPS triggered macrophages and dendritic cell activation upon binding to Dectin-1, a pattern recognition receptor of the C-type lectin receptor family. Engagement of Dectin-1 culminated in pro-inflammatory cytokine production and cell maturation via its canonical Syk-dependent pathway signaling. Furthermore, upon EPS treatment, M2-like phenotype macrophages, known to support intracellular survival and replication of C. neoformans, repolarize to M1 macrophage pattern associated with enhanced production of the microbicidal molecule nitric oxide that results in efficient killing of C. neoformans. Treatment with EPS also upregulated transcript levels of genes encoding products associated with host protection against C. neoformans and Dectin-1 mediated signaling in macrophages. Finally, orally administrated β-glucan-containing EPS from A. auricular enhanced the survival of mice infected with C. neoformans. In conclusion, the results demonstrate that EPS from A. auricula exert immunostimulatory activity in phagocytes and induce host protection against C. neoformans, suggesting that polysaccharides from this mushroom may be promising as an adjuvant for vaccines or antifungal therapy.

Health effects of heating, ventilation and air conditioning on hospital patients: a scoping review

Background

In the face of climate change, the protection of vulnerable patients from extreme climatic conditions is of growing interest to the healthcare sector and governments. Inpatients are especially susceptible to heat due to acute illness and/or chronic diseases. Their condition can be aggravated by adverse environmental factors. Installing air conditioning can be seen as an element of public health adaptation because it was shown to improve mortality rates of hospital patients experiencing hot temperatures. Still, the mediating factors and resulting health effects are largely unknown.

Method

The PRISMA-ScR guideline was followed for this scoping review. Available evidence on the health effects of Heating, Ventilation, Air Conditioning (HVAC) and fans was searched in Medline, Embase and the Cochrane Library. The focus of the search strategy was on inpatients of the hospital. Grey literature was screened on 14 relevant websites. English and German publications were eligible without restrictions on publication date. Results were charted according to the categories population, intervention, control and outcome together with a qualitative description.

Results

The review process yielded eleven publications of which seven were issued after 2003. Seven were clinical trials, three cross-sectional studies and one was a case report. The publications described the installation of HVAC on general wards and in intensive care units. Main topics were heat stress protection and support of thermoregulation, but also the rewarming of hypothermic patients. HVAC use resulted in a recovery effect shown by improved vital signs, reduced cardiac stress, accelerated recuperation and greater physical activity. This protective effect was demonstrated by a shorter hospital stay for patients with respiratory disease and a reduction of mortality for heat illness patients.

Conclusion

This scoping review summarises the fragmented evidence on health effects of HVAC and fan utilisation for inpatients. Installing HVAC has the potential to improve patients’ outcomes and to make hospital treatment more efficient during heat waves. The application of HVAC could be a promising adaptation measure to mitigate the adverse effects of climate change on health and healthcare systems.

[Direct oral anticoagulants: In which indications? Which one to prescribe? For or against their use in frail patients and in atypical cases? Which monitoring and management haemorrhage complications?]

Since their approval, the direct oral anticoagulants have been widely used in the management of venous thromboembolism, for stroke and systemic embolism prevention in non valvular atrial fibrillation, and in venous thromboembolism prophylaxis after surgical hip or knee replacement. Because they are easy to use, with oral fixed doses and no biological monitoring need, they are more and more prescribed. New indications are rising in cancer associated thrombosis in France beyond the 6 first months of treatment, and to prevent cardiovascular events after an acute coronary syndrome, or in stable coronary or peripheral arterial disease in Europe. The efficacity and safety of direct oral anticoagulants in frail patients or in unusual pathological contexts are not entirely known, but further data are coming and will probably bring new answers.

Two-level ACDF with a zero-profile stand-alone spacer compared to conventional plating: a prospective randomized single-center study

PURPOSE

Stand-alone zero-profile devices have already proven safety, and a reduced dysphagia rate was assumed. So far, no level-one evidence is available to prove the proposed advantages of zero-profile implants in multilevel procedures. The aim of this RCT was to compare the clinical and radiological outcome of a zero-profile spacer versus cage + plate in two-level ACDF.

METHODS

Consecutive patients with contiguous two-level cDD were randomly assigned either to the interventional group (zero-profile device) or to the control group (cage + plate). Primary endpoint of the study was the prevalence of dysphagia at 24 months. Disability, progress of adjacent segment degeneration, fusion status and loss of correction were analyzed as secondary outcome measure. Primary outcome parameter was statistically analyzed by Chi-square test.

RESULTS

Forty-one patients met inclusion criteria and were randomly assigned to the interventional and the control group. Dysphagia was frequent in either group at 3 months FU favoring interventional group (p = 0.078). At final FU, less patients of the interventional group complained about dysphagia, but the difference was not significant. No relevant differences at final FU were recorded for NPDI, loss of correction and adjacent-level degeneration. Fusion rate was slightly lower in the interventional group.

DISCUSSION

Two-level ACDF either by a stand-alone zero-profile spacer or cage + plate is safe. Using a zero-profile cage dysphagia was infrequent at 24 months, but the value did not reach statistical significance in comparison with the cage + plate. Hence, this randomized trial was not able to prove the proposed clinical superiority for dysphagia rates for zero-profile anchored spacer in two-level cDD.

Strong hydrogen bonding in a dense hydrous magnesium silicate discovered by neutron Laue diffraction

A large amount of hydrogen circulates inside the Earth, which affects the long-term evolution of the planet. The majority of this hydrogen is stored in deep Earth within the crystal structures of dense minerals that are thermodynamically stable at high pressures and temperatures. To understand the reason for their stability under such extreme conditions, the chemical bonding geometry and cation exchange mechanism for including hydrogen were analyzed in a representative structure of such minerals (i.e. phase E of dense hydrous magnesium silicate) by using time-of-flight single-crystal neutron Laue diffraction. Phase E has a layered structure belonging to the space group R 3 m and a very large hydrogen capacity (up to 18% H₂O weight fraction). It is stable at pressures of 13-18 GPa and temperatures of up to at least 1573 K. Deuterated high-quality crystals with the chemical formula Mg_2.28Si_1.32D_2.15O₆ were synthesized under the relevant high-pressure and high-temperature conditions. The nuclear density distribution obtained by neutron diffraction indicated that the O-D dipoles were directed towards neighboring O^2- ions to form strong interlayer hydrogen bonds. This bonding plays a crucial role in stabilizing hydrogen within the mineral structure under such high-pressure and high-temperature conditions. It is considered that cation exchange occurs among Mg²⁺, D⁺ and Si⁴⁺ within this structure, making the hydrogen capacity flexible.

Neuroimaging Findings in Children with Constitutional Mismatch Repair Deficiency Syndrome

BACKGROUND AND PURPOSE

Constitutional mismatch repair deficiency is a hereditary childhood cancer predisposition syndrome characterized by brain tumors and colorectal and hematologic malignancies. Our objective was to describe the neuroimaging findings in patients with constitutional mismatch repair deficiency.

MATERIALS AND METHODS

This retrospective study included 14 children with genetically confirmed constitutional mismatch repair deficiency who were referred to 2 tertiary pediatric oncology centers.

RESULTS

Fourteen patients from 11 different families had diagnosed constitutional mismatch repair deficiency. The mean age at presentation was 9.3 years (range, 5-14 years). The most common clinical presentation was brain malignancy, diagnosed in 13 of the 14 patients. The most common brain tumors were glioblastoma (n = 7 patients), anaplastic astrocytoma (n = 3 patients), and diffuse astrocytoma (n = 3 patients). Nonspecific subcortical white matter T2 hyperintensities were noted in 10 patients (71%). Subcortical hyperintensities transformed into overt brain tumors on follow-up imaging in 3 patients. Additional non-neoplastic brain MR imaging findings included developmental venous anomalies in 12 patients (85%) and nontherapy-induced cavernous hemangiomas in 3 patients (21%).

CONCLUSIONS

On brain MR imaging, these patients have both highly characteristic intra-axial tumors (typically multifocal high-grade gliomas) and nonspecific findings, some of which might represent early stages of neoplastic transformation. The incidence of developmental venous anomalies is high in these patients for unclear reasons. Awareness of these imaging findings, especially in combination, is important to raise the suspicion of constitutional mismatch repair deficiency in routine diagnostic imaging evaluation or surveillance imaging studies of asymptomatic carriers because early identification of the phenotypic "gestalt" might improve outcomes.

K-space algorithmic reconstruction (KAREN): a robust statistical methodology to separate Bragg and diffuse scattering

Diffuse scattering occurring in the Bragg diffraction pattern of a long-range-ordered structure represents local deviation from the governing regular lattice. However, interpreting the real-space structure from the diffraction pattern presents a significant challenge because of the dramatic difference in intensity between the Bragg and diffuse components of the total scattering function. In contrast to the sharp Bragg diffraction, the diffuse signal has generally been considered to be a weak expansive or continuous background signal. Herein, using 1D and 2D models, it is demonstrated that diffuse scattering in fact consists of a complex array of high-frequency features that must not be averaged into a low-frequency background signal. To evaluate the actual diffuse scattering effectively, an algorithm has been developed that uses robust statistics and traditional signal processing techniques to identify Bragg peaks as signal outliers which can be removed from the overall scattering data and then replaced by statistically valid fill values. This method, described as a `K-space algorithmic reconstruction' (KAREN), can identify Bragg reflections independent of prior knowledge of a system's unit cell. KAREN does not alter any data other than that in the immediate vicinity of the Bragg reflections, and reconstructs the diffuse component surrounding the Bragg peaks without introducing discontinuities which induce Fourier ripples or artifacts from underfilling `punched' voids. The KAREN algorithm for reconstructing diffuse scattering provides demonstrably better resolution than can be obtained from previously described punch-and-fill methods. The superior structural resolution obtained using the KAREN method is demonstrated by evaluating the complex ordered diffuse scattering observed from the neutron diffraction of a single plastic crystal of CBr4 using pair distribution function analysis.