The arcuate fasciculus: Combining structure and function into surgical considerations.

BACKGROUND: Two Centuries from today, Karl Friedrich Burdach attributed the nomenclature "arcuate fasciculus" to a white matter (WM) pathway connecting the frontal to the temporal cortices by arching around the Sylvian fissure. Although this label remained essentially unvaried, the concepts related to it and the characterization of the structural properties of this bundle evolved along with the methodological progress of the past years. Concurrently, the functional relevance of the arcuate fasciculus (AF) classically restricted to the linguistic domain has extended to further cognitive abilities. These features make it a relevant structure to consider in a large variety of neurosurgical procedures. OBJECTIVE: Herein, we build on our previous review uncovering the connectivity provided by the Superior Longitudinal System, including the AF, and provide a handy representation of the structural organization of the AF by considering the frequency of defined reports in the literature. By adopting the same approach, we implement an account of which functions are mediated by this WM bundle. We highlight how this information can be transferred to the neurosurgical field by presenting four surgical cases of glioma resection requiring the evaluation of the relationship between the AF and the nearby structures, and the safest approaches to adopt. CONCLUSIONS: Our cumulative overview reports the most common wiring patterns and functional implications to be expected when approaching the study of the AF, while still considering seldom descriptions as an account of interindividual variability. Given its extension and the variety of cortical territories it reaches, the AF is a pivotal structure for different cognitive functions, and thorough understanding of its structural wiring and the functions it mediates is necessary for preserving the patient's cognitive abilities during glioma resection.

The structural connectivity of the human angular gyrus as revealed by microdissection and diffusion tractography.

The angular gyrus (AG) has been described in numerous studies to be consistently activated in various functional tasks. The angular gyrus is a critical connector epicenter linking multiple functional networks due to its location in the posterior part of the inferior parietal cortex, namely at the junction between the parietal, temporal, and occipital lobes. It is thus crucial to identify the different pathways that anatomically connect this high-order association region to the rest of the brain. Our study revisits the three-dimensional architecture of the structural AG connectivity by combining state-of-the-art postmortem blunt microdissection with advanced in vivo diffusion tractography to comprehensively describe the association, projection, and commissural fibers that connect the human angular gyrus. AG appears as a posterior "angular stone" of associative connections belonging to mid- and long-range dorsal and ventral fibers of the superior and inferior longitudinal systems, respectively, to short-range parietal, occipital, and temporal fibers, including U-shaped fibers in the posterior transverse system. Thus, AG is at a pivotal dorso-ventral position reflecting its critical role in the different functional networks, particularly in language elaboration and spatial attention and awareness in the left and right hemispheres, respectively. We also reveal striatal, thalamic, and brainstem connections and a typical inter-hemispheric homotopic callosal connectivity supporting the suggested AG role in the integration of sensory input for modulating motor control and planning. The present description of AG's highly distributed wiring diagram may drastically improve intraoperative subcortical testing and post-operative neurologic outcomes related to surgery in and around the angular gyrus.

May the initial CT scan predict the occurrence of delayed hemothorax in blunt chest trauma patients?

PURPOSE: To assess the impact of delayed hemothorax on outcomes in blunt chest trauma patients without life-threatening condition at admission and characterize the predictive value of predefined anatomical factors for delayed hemothorax. METHODS: In a single-centre retrospective study, every spontaneous breathing patient admitted for a blunt chest trauma without significant pleural effusion at ICU admission was included. A multivariable regression model was used to determine the covariate-adjusted odd of secondary respiratory complications in patients with delayed hemothorax ≥ 500 ml. The characteristics of rib fractures (number, location and displacement) were integrated into a logistic regression model to determine variables associated with delayed hemothorax in multivariate analysis. RESULTS: Over the study period, 109 patients were included and the rate of delayed hemothorax ≥ 500 ml was 36%. Patients with delayed hemothorax had higher rates of pulmonary infections (OR 4.8 [1.6-16.4]) but no statistical association between delayed hemothorax and secondary respiratory failure (OR 2.0 [0.4-9.4]). A posterior location and a displaced rib fracture were independent predictors of delayed hemothorax (OR 3.4 [1.3-8.6] and OR 2.3 [1.1-5.1], respectively). At least one displaced rib fracture was more specific of delayed hemothorax than the commonly used threshold of three or more rib fractures (81.3 vs. 51.5%). CONCLUSION: Delayed hemothorax is a frequent complication associated with increased risk of pulmonary infection. The posterior location and the displacement of at least one rib fracture in the initial CT scan were independent risk factors for predicting the occurrence of delayed hemothorax.

Piperacillin-tazobactam should be preferred to third-generation cephalosporins to treat wild-type inducible AmpC-producing Enterobacterales in critically ill patients with hospital or ventilator-acquired pneumonia.

PURPOSE: To compare the rate of therapeutic failure in critically ill patients treated by third-generation cephalosporins (3GCs) or piperacillin-tazobactam (PTZ) for wild-type AmpC-producing Enterobacterales pulmonary infections. METHODS: Over a 4-year period, all adult patients treated for a wild-type AmpC-producing Enterobacterales pulmonary infection were retrospectively included. Two groups of patients were compared according to the definitive antibiotic therapy (3GCs or PTZ) considered after <48 h of empirical antibiotic therapy. The main outcome was the rate of therapeutic failure (impaired clinical response under treatment and/or a relapse of pulmonary infection). The secondary outcome was a secondary acquisition of 3GCs resistance. RESULTS: Over the study period, 244 patients were included; 56 (23%) experienced therapeutic failure. In the non-adjusted cohort, the rate of therapeutic failure and emergence of resistance were significantly higher in the 3GCs group (32 vs. 18%, p = .011 and 13 vs. 5%, p = .035, respectively). In the propensity score-matched population, the use of 3GCs was associated with higher rates of therapeutic failure (HR = 1.61 [1.27-2.07]). The secondary de-escalation to 3GCs after 48 h of PTZ as a first-line antibiotic therapy was not associated with increased rate of emergence of resistance. CONCLUSION: Our study confirms that 3GCs should be avoided as first-line antibiotic therapy in wild-type AmpC-producing Enterobacterales pulmonary infections.

Brimonidine displays anti-inflammatory properties in the skin through the modulation of the vascular barrier function.

BACKGROUND: Rosacea is a chronic inflammatory skin disease. Characteristic vascular changes in rosacea skin include enlarged, dilated vessels of the upper dermis and blood flow increase. Brimonidine is approved for symptomatic relief of the erythema of rosacea. It acts by selectively binding to α2-adrenergic receptors present on smooth muscle in the peripheral vasculature, resulting in transient local vasoconstriction. OBJECTIVES: To provide further evidence of the anti-inflammatory potential of brimonidine across preclinical models of skin inflammation and its ability to decrease the neutrophil infiltration in human skin after ultraviolet light exposure. METHODS: The anti-inflammatory properties of brimonidine through modulation of the vascular barrier function were assessed using in vivo neurogenic vasodilation and acute inflammatory models and a well-described in vitro transmigration assay. A clinical study assessed the neutrophil infiltration in human skin after exposure to UV in 37 healthy Caucasian male subjects. RESULTS: In vitro, brimonidine affects the transmigration of human neutrophils through the endothelial barrier by modulating adhesion molecules. In vivo, in the mouse, topical treatment with brimonidine, used at a vasoconstrictive dose, confirmed its anti-inflammatory properties and prevented leucocyte recruitment (rolling and adhesion) mediated by endothelial cells. Topical pretreatment with brimonidine tartrate 0.33% gel once a day for 4 days significantly prevented neutrophil infiltration by 53.9% in human skin after exposure to UV light. CONCLUSION: Results from in vitro, in vivo and from a clinical study indicate that brimonidine impacts acute inflammation of the skin by interfering with neurogenic activation and/or recruitment of neutrophils.

The link between structural connectivity and neurocognition illustrated by focal epilepsy.

Increasing attention is being paid to the assessment of white matter properties and its structural connectivity, both in healthy subjects and patients with cerebral lesions. Within this framework, new neurocognitive models based on hodological properties have been developed under a connectomic perspective in order to explain substrates and cognitive mechanisms related to cerebral functions such as language and memory. With regards to focal and drug-resistant epilepsy conceived as a network disorder, new insights in terms of structural connectivity have led to significant advances in epilepsy research, concerning fundamental research (neurocognitive mechanisms of plasticity) and clinical application (optimization of decision making for curative surgery). We believe that such findings in the literature, focused on the role of white matter in cerebral functioning in relation to neurocognition, may be helpful for both researchers and clinicians working in the field of epilepsy.

Recognition of white matter bundles using local and global streamline-based registration and clustering.

Virtual dissection of diffusion MRI tractograms is cumbersome and needs extensive knowledge of white matter anatomy. This virtual dissection often requires several inclusion and exclusion regions-of-interest that make it a process that is very hard to reproduce across experts. Having automated tools that can extract white matter bundles for tract-based studies of large numbers of people is of great interest for neuroscience and neurosurgical planning. The purpose of our proposed method, named RecoBundles, is to segment white matter bundles and make virtual dissection easier to perform. This can help explore large tractograms from multiple persons directly in their native space. RecoBundles leverages latest state-of-the-art streamline-based registration and clustering to recognize and extract bundles using prior bundle models. RecoBundles uses bundle models as shape priors for detecting similar streamlines and bundles in tractograms. RecoBundles is 100% streamline-based, is efficient to work with millions of streamlines and, most importantly, is robust and adaptive to incomplete data and bundles with missing components. It is also robust to pathological brains with tumors and deformations. We evaluated our results using multiple bundles and showed that RecoBundles is in good agreement with the neuroanatomical experts and generally produced more dense bundles. Across all the different experiments reported in this paper, RecoBundles was able to identify the core parts of the bundles, independently from tractography type (deterministic or probabilistic) or size. Thus, RecoBundles can be a valuable method for exploring tractograms and facilitating tractometry studies.

Adenoma detection with blue-water infusion colonoscopy: a randomized trial.

Background and aims Colonoscopy is currently the reference method to detect colorectal neoplasia, yet some adenomas remain undetected. The water infusion technique and dying with indigo carmine has shown interesting results for reducing this miss rate. The aim of this study was to compare the adenoma detection rate (adenoma and adenocarcinoma; ADR) and the mean number of adenomas per patient (MAP) for blue-water infusion colonoscopy (BWIC) versus standard colonoscopy. Methods We performed a multicenter, randomized controlled trial in eight units, including patients with a validated indication for colonoscopy (symptoms, familial or personal history, fecal occult blood test positive). Consenting patients were randomized 1:1 to BWIC or standard colonoscopy. All colonoscopies were performed by experienced colonoscopists. All colonoscopy quality indicators were prospectively recorded. Results Among the 1065 patients included, colonoscopies were performed completely for 983 patients (514 men; mean age 59.1). The ADR was not significantly different between the groups; 40.4 % in the BWIC group versus 37.5 % in the standard colonoscopy group (odds ratio [OR] 1.13; 95 % confidence interval [CI] 0.87 - 1.48; P = 0.35). MAP was significantly greater in the BWIC group (0.79) than in the standard colonoscopy group (0.64; P = 0.005). For advanced adenomas, the results were 50 (10.2 %) and 36 (7.3 %), respectively (P = 0.10). The cecal intubation rate was not different but the time to cecal intubation was significantly longer in BWIC group (9.9 versus 6.2 minutes; P < 0.001). Conclusion Despite the higher MAP with BWIC, the routine use of BWIC does not translate to a higher ADR. Whether increased detection ultimately results in a lower rate of interval carcinoma is not yet known. CLINICAL TRIALS REGISTRATION: EudraCT 2012-A00548 - 35; NCT01937429.

Osteoclasts and their precursors are present in the induced-membrane during bone reconstruction using the Masquelet technique.

In 2000, Masquelet reported a long bone reconstruction technique using an induced membrane formed around a polymethylmethacrylate (PMMA) spacer placed in the defect with appropriate stabilization followed by secondary bone graft after PMMA removal. This reconstruction procedure allows rapid and safe bone reformation for septic, traumatic, neoplastic or congenital bone defects. A rat model of the Masquelet technique was developed to further characterize the biological activities of this induced membrane. Our model allows healing of a critical-sized femoral defect (8 mm) by means of this procedure over a period of 18 weeks. Comparison of induced membranes obtained 3, 4, 5 and 6 weeks after PMMA insertion indicated that this tissue changes over time. Several mineralization spots and bone cells were observed in contact with the PMMA, when assessed by Alizarin Red, Von Kossa, Alkaline phosphatase and Tartrate-resistant acid phosphatase staining of the membranes. CTR (calcitonin receptor)- and RANK (Receptor Activator of Nuclear factor Kappa B)- positive mononuclear cells were detected in the induced membrane, confirming the presence of osteoclasts in this tissue. These cells were observed in a thin, highly cellular layer in the induced membrane in contact with the PMMA. Together, these findings suggest that the membrane is able to promote osteointegration of autologous corticocancellous bone grafts during the Masquelet technique by creating local conditions that may be favourable to graft bone remodelling and osteointegration. Copyright © 2014 John Wiley & Sons, Ltd.

Strontium ranelate decreases receptor activator of nuclear factor-ΚB ligand-induced osteoclastic differentiation in vitro: involvement of the calcium-sensing receptor.

Strontium ranelate exerts both an anticatabolic and an anabolic effect on bone cells. To further investigate the mechanism by which strontium ranelate inhibits bone resorption, the effects of varying concentrations of Sr(o)(2+) on osteoclastic differentiation were studied using RAW 264.7 cells and peripheral blood monocytic cells (PBMCs). We report that increasing concentrations of Sr(o)(2+) down-regulate osteoclastic differentiation and tartrate-resistant acid phosphatase activity, leading to inhibition of bone resorption (-48% when PBMCs were cultured for 14 days in the presence of 2 mM Sr(o)(2+)). Using a dominant-negative form of the calcium-sensing receptor (CaR) and a small interfering RNA approach, we provide evidences that the inhibition of osteoclast differentiation by Sr(o)(2+) is mediated by stimulation of the CaR. Moreover, our results suggest that the effects of Sr(o)(2+) on osteoclasts are, at least in part, mediated by inhibition of the receptor activator of nuclear factor-κB ligand (RANKL)-induced nuclear translocation of nuclear factor-κB and activator protein-1 in the early stages of osteoclastic differentiation. In conclusion, our data indicate that Sr(2+) directly inhibits the formation of mature osteoclasts through down-regulation of RANKL-induced osteoclast differentiation and decreases osteoclast differentiation through the activation of the CaR.

Phase I study of daily irinotecan as a radiation sensitizer for locally advanced pancreatic cancer.

PURPOSE: The study aimed to determine the maximum tolerated dose of daily irinotecan given with concomitant radiotherapy in patients with locally advanced adenocarcinoma of the pancreas. METHODS AND MATERIALS: Between September 2000 and March 2008, 36 patients with histologically proven unresectable pancreas adenocarcinoma were studied prospectively. Irinotecan was administered daily, 1 to 2 h before irradiation. Doses were started at 6 mg/m(2) per day and then escalated by increments of 2 mg/m(2) every 3 patients. Radiotherapy was administered in 2-Gy fractions, 5 fractions per week, up to a total dose of 50 Gy to the tumor volume. Inoperability was confirmed by a surgeon involved in a multidisciplinary team. All images and responses were centrally reviewed by radiologists. RESULTS: Thirty-six patients were enrolled over a period of 8 years through eight dose levels (6 mg/m(2) to 20 mg/m(2) per day). The maximum tolerated dose was determined to be 18 mg/m(2) per day. The dose-limiting toxicities were nausea/vomiting, diarrhea, anorexia, dehydration, and hypokalemia. The median survival time was 12.6 months with a median follow-up of 53.8 months. The median progression-free survival time was 6.5 months, and 4 patients (11.4%) with very good responses could undergo surgery. CONCLUSIONS: The maximum tolerated dose of irinotecan is 18 mg/m(2) per day for 5 weeks. Dose-limiting toxicities are mainly gastrointestinal. Even though efficacy was not the aim of this study, the results are very promising, with a median survival time of 12.6 months.

Implication of the calcium sensing receptor and the Phosphoinositide 3-kinase/Akt pathway in the extracellular calcium-mediated migration of RAW 264.7 osteoclast precursor cells.

While the processes involved in the formation, maturation and apoptosis of osteoclasts have been investigated extensively in previous studies, little is known about the mechanisms responsible for the localization and homing of osteoclast precursor cells to the bone environment in order to initiate the bone remodeling process. Recent studies have suggested that the extracellular Ca(2+) (Ca(2+)(o)) concentration gradient present near the bone environment may be one of the participating factors, producing a chemoattractant effect on osteoclast precursors. Using the murine osteoclast precursor cells of the monocyte-macrophage lineage, the RAW 264.7 cell line, we have shown that Ca(2+)(o) increases the migration of these cells in a directional manner. The participation of the calcium sensing receptor (CaR) in this effect was tested by knocking down its expression through RNA interference, which resulted in an abolition of the migratory response. By the use of specific pathway inhibitors and western blot analysis, the phosphoinositide 3-kinase (PI3K)/Akt and phospholipase Cbeta pathways were shown to be implicated in the migratory effect. The implication of the Akt pathway in the Ca(2+)(o)-induced chemoattraction of RAW 264.7 cells was also confirmed by transducing the cells with the fusion protein TAT-dominant negative-Akt, which decreased the migratory effect. In contrast, the MAPK pathways (ERK1/2, p38 and JNK) were not involved in the production of the migratory effect. We conclude that through the activation of the CaR and subsequent signaling via the PI3K/Akt pathway, Ca(2+)(o) produces a chemoattractant effect on the osteoclast precursor RAW 264.7 cells. These results suggest that the Ca(2+)(o) gradient present near the bone may be one of the initiating factors for the homing of osteoclast precursors to bone, thus possibly playing a role in the initiation of bone remodeling.

Extracellular calcium promotes the migration of breast cancer cells through the activation of the calcium sensing receptor.

Breast cancer is the most frequent form of cancer in women, with the highest incidence of metastasis to the bone. The reason for the preferential destination to the bone is believed to be due to chemoattractant factors released during bone resorption, which act on the cancer cells facilitating their metastasis. One of the factors released during osteolysis that may mediate breast cancer bone localization is Ca2+. Here, we show that extracellular Ca2+ (Ca2+(o)) acting via the calcium-sensing receptor (CaSR), greatly promotes the migration of bone-preferring breast cancer cells. In Boyden Chamber and Scratch Wound migration assays, an increase in breast cancer cell migration was observed at 2.5 mM and 5 mM Ca2+(o) compared to basal levels for three of the four breast cancer cell lines tested. However, a significantly greater migratory response was observed for the highly bone metastatic MDA-MB-231 cells, compared to the MCF7 and T47D, which have a lower metastatic potential in vivo. The BT474 cells, which do not metastasize to the bone, did not respond to elevated concentrations of Ca2+(o) in the migration assays. Inhibition of either ERK1/2 MAPK or phospholipase Cbeta (PLCbeta) led to an abolition of the Ca2+(o)-induced migration, implicating these pathways in the migratory response. Knockdown of the CaSR by siRNA resulted in an inhibition of the Ca2+(o)-induced migration, demonstrating the involvement of this receptor in the effect. These results suggest that the activation of the CaSR by elevated Ca2+(o) concentrations, such as those found near resorbing bone, produces an especially strong chemoattractant effect on bone metastatic breast cancer cells toward the Ca2+-rich environment.

Prospective evaluation of a new ultrathin one-plane bending videoendoscope for transnasal EGD: a comparative study on performance and tolerance.

BACKGROUND: EGD, with small-diameter endoscopes, is routinely performed via a nasal route in adults. OBJECTIVE: To evaluate a new ultrathin one-plane bending videoendoscope for transnasal EGD. DESIGN: Single center, prospective, randomized study. SETTING: Edouard Herriot University Hospital. PATIENTS: A total of 122 outpatients (median age, 49 years [18-81 years], 62 men and 60 women) were randomized into 2 groups (on a 2:1 basis) according to the endoscope used: (1) a standard 5.9-mm-diameter videoendoscope (80 patients) or (2) a one-plane bending high resolution 4.9-mm-diameter videoendoscope (42 patients). MAIN OUTCOME MEASUREMENTS: The operator assessed the quality of examination by using standard scores or a 100-mm visual scale. Patients quantified tolerance by using a 100-mm visual scale. RESULTS: The duration of the procedure was the same in each group. The feasibility of transnasal insertion was significantly higher when using the 4.9-mm-diameter endoscope (97.61% [41/42 patients] vs 88.75% [71/80 patients], P<.05). The tolerance of EGD was significantly better in the group with the small videoendoscope, for global discomfort, pain, belching, and bloating. Similarly, acceptation of a new EGD in similar conditions was higher in group 2 (92.9% vs 80%, P<.05). The quality of examination (global, lavage, inflation, suction) was not different between the 2 groups. LIMITATIONS: Evaluation of patient tolerance and quality of examination was based on subjective features. CONCLUSIONS: Availability of a new ultrathin one-plane bending videoendoscope represents a major technical improvement for transnasal EGD, which significantly improves both feasibility and patient tolerance, without affecting the quality of the examination.