Diffusion tensor imaging in the study of language and aphasia

Background: Diffusion tensor imaging (DTI) is an emerging research technique that is used to map and characterise white matter tracts in the healthy and damaged brain.

Aims: The aim of this paper is to familiarise the readers with DTI while giving the tools to understand and evaluate recent developments in aphasia research that use DTI methodology.

Main Contribution: Principles of DTI technology as well as its main caveats are described. An overview of studies that used DTI to explore the language system and aphasia is given. Future directions and the potential contribution of DTI to the understanding of aphasia diagnosis and recovery are highlighted.

Conclusions: DTI is an emerging technology, increasingly being applied to further our understanding of aphasia and its recovery. So far it has contributed to our knowledge in four areas of research. In the area of brain anatomy it is used to redefine the borders between various parts of the cortex based on their structural connectivity, to acquire a more accurate map of the tracts connecting the various parts of the language system, and to measure hemispheric asymmetry. Future studies might be able to further our understanding of language anatomy and relate hemispheric asymmetry to recovery potential. Second, DTI can help in relating structure to function. So far many studies focused on repetition deficits and conduction aphasia. Future studies can explore the anatomy of other language deficits. Third, DTI has been used in the study of brain damage and recovery. Studies have documented the damage that occurs to white matter following stroke and other insults, and the spontaneous reorganisation that follows. In the future DTI might contribute to the debate about the role of the right hemisphere in recovery from aphasia. Lastly, in the area of aphasia rehabilitation there is great lack of data. The studies reviewed here have shown that rehabilitation potential is dependent on white matter integrity and that white matter changes can occur as a result of therapy. Future studies should further our understanding of the role of white matter integrity in recovery, therefore contributing to the question of why some patients show good recovery while others do not. Future studies should also try and map white matter changes that are associated with successful versus unsuccessful rehabilitation, and with different stages of recovery.     

Human Cytomegalovirus Inhibits the PARsylation Activity of Tankyrase—A Potential Strategy for Suppression of the Wnt Pathway

Human cytomegalovirus (HCMV) was reported to downregulate the Wnt/β-catenin pathway. Induction of Axin1, the negative regulator of the Wnt pathway, has been reported as an important mechanism for inhibition of β-catenin. Since Tankyrase (TNKS) negatively regulates Axin1, we investigated the effect of HCMV on TNKS expression and poly-ADP ribose polymerase (PARsylation) activity, during virus replication. Starting at 24 h post infection, HCMV stabilized the expression of TNKS and reduced its PARsylation activity, resulting in accumulation of Axin1 and reduction in its PARsylation as well. General PARsylation was not changed in HCMV-infected cells, suggesting specific inhibition of TNKS PARsylation. Similarly, treatment with XAV939, a chemical inhibitor of TNKS’ activity, resulted in the accumulation of TNKS in both non-infected and HCMV-infected cell lines. Reduction of TNKS activity or knockdown of TNKS was beneficial for HCMV, evidenced by its improved growth in fibroblasts. Our results suggest that HCMV modulates the activity of TNKS to induce Axin1, resulting in inhibition of the β-catenin pathway. Since HCMV replication is facilitated by TNKS knockdown or inhibition of its activity, TNKS may serve as an important virus target for control of a variety of cellular processes.     

Intérêt du test HPV dans le dépistage primaire du cancer du col en milieu rural à Madagascar

Background

Testing for high-risk human papilloma virus (HR-HPV) is an effective approach to the prevention of cervical cancer. This study in the Atsinanana area of Madagascar aimed to compare the management of women screened by visual inspection after coloration with acetic acid (VIA) and the management of women screened by HPV with VIA as a triage test.

Accuracy of guideline recommendations for two-dimensional quantification of the right ventricle by echocardiography

Background The accuracy of the guidelines of the American Society of Echocardiography (ASE) for the two-dimensional (2D) quantitative assessment of right ventricular (RV) size and function has not been evaluated against MRI-derived RV volumes in patients with congenital heart disease and RV volume overload. Methods Three groups of patients were studied: a normal RV group (Group I, n = 31), a repaired tetralogy of Fallot group (Group II, n = 33), and an unrepaired atrial septal defect and/or partially anomalous pulmonary venous connection group (Group III, n = 23). Recommended 2D linear and cross-sectional area measurements were made on clinical echocardiographic and MRI studies performed less than 6 months apart. Results Most 2D RV parameters were smaller by echocardiography versus MRI. There was weak correlation between 2D RV measurements by echocardiography and MRI-derived RV volumes (Group I: r = 0.15-0.54, Group II: r = 0.33-0.61, Group III: r = 0.32-0.85), and only modest improvement when the same 2D measurements were performed by MRI (Group I: r = 0.37-0.61, Group II: r = 0.44-0.69, Group III: r = 0.28-0.74). The difference between 2D RV measurements by echocardiography and MRI-derived RV volumes was more pronounced in the RV volume overload groups. Conclusions The correlation between currently recommended 2D RV measurements by echocardiography and MRI-derived RV volumes was weak, and improved only modestly when MRI was used to make the same 2D measurements. Moreover, 2D echocardiographic assessment of the RV appears to be less accurate in patients with congenital heart disease and a dilated RV.     

Echocardiography and magnetic resonance imaging based strain analysis of functional single ventricles: a study of intra- and inter-modality reproducibility

The purpose of this study was to measure reproducibility in strain measurements by echocardiography and cardiac magnetic resonance imaging (CMR) in functional single ventricles in the Fontan circulation. Fontan echocardiograms and CMRs between 1/2005 and 6/2013 were analyzed retrospectively. Patients were included if studies occurred <1 year apart and without interim catheter-based or surgical intervention. Global peak systolic circumferential (GCS) and longitudinal (GLS) strain, and strain rates (GCSR and GLSR) were measured by speckle or feature tracking (echocardiogram vs. CMR) using commercial software. 134 study pairs were identified; 74 with dominant left and 60 with dominant right ventricles. Agreement for strain and strain rate between echocardiogram and CMR was modest for circumferential measurements, concordance correlation coefficient (Rc)?=?0.56 for GCS, 0.44 for GCSR; and low for longitudinal measurements, Rc?=?0.34 for GLS, and 0.27 for GLSR. There was good inter-observer agreement (n?=?30) for strain measurements by echocardiogram and CMR (echocardiogram GCS Rc?=?0.84, echocardiogram GLS Rc?=?0.79, CMR GCS Rc?=?0.94, CMR GLS Rc?=?0.75). Inter-observer agreement for strain rate was slightly lower (echocardiogram GCSR Rc?=?0.79, echocardiogram GLSR Rc?=?0.73, CMR GCSR Rc?=?0.93, CMR GLSR Rc?=?0.54). Coefficients for intra-observer agreement for these variables were similar to inter-observer agreement. In conclusion, intra-modality reproducibility for strain assessment in functional single ventricles in the Fontan circulation is high, measured both by echocardiography and CMR; inter-modality reproducibility, however, is modest. These findings caution against mixing values from multiple modalities in the long-term assessment of patient health in this population.     

Perioperative Complications After Neoadjuvant Chemotherapy With and Without Bevacizumab for Colorectal Liver Metastases

Purpose

Bevacizumab has been shown to increase progression free and overall survival in patients with metastatic colorectal cancer. Neoadjuvant bevacizumab is commonly used in patients undergoing liver resection. Our purpose was to evaluate whether bevacizumab is associated with increased rate of perioperative complications in patients undergoing hepatic resection for colorectal liver metastases (CRLM).

Methods

Retrospective analysis of patients undergoing hepatic resection for CRLM who received chemotherapy and bevacizumab (group 1, n?=?134), or chemotherapy alone (group 2, n?=?57). We compared demographics, surgical characteristics, and perioperative course.

Results

Perioperative complications developed in 35 % of patients in group 1, and 47 % in group 2 (p?=?0.11). Of those complications, 15 (11.2 %) in group 1, and 5 (8.8 %) in group 2 were considered major (p?=?0.617). Four patients, all of whom received preoperative bevacizumab, developed enteric leaks following combined liver and bowel resection. The rate of anastomotic leak in group 1 was 10 %, compared with 0 in group 2, p?=?0.56.

Conclusion

Neoadjuvant chemotherapy along with bevacizumab was not associated with an increased risk of postoperative complications after hepatic resection. Possible association of increased morbidity with simultaneous bowel and liver resections following bevacizumab administration was found and we recommend avoiding such treatment combination.     

Recurrent atrioventricular groove intramuscular arteriovenous malformation

A 17-year-old patient presented with a recurrent right atrioventricular (AV) groove vascular tumor. The tumor was resected en bloc, including the AV groove extending into the right ventricle (RV) and tricuspid valve. The AV groove and tricuspid valve required extensive reconstruction. The histopathologic features were that of an arteriovenous malformation with a proliferative small vessel component--an extremely rare type of cardiovascular anomaly.