Semantic memory is the subsystem of human memory that stores knowledge of concepts or meanings, as opposed to life-specific experiences. How humans organize semantic information remains poorly ...understood. In an effort to better understand this issue, we conducted a verbal fluency experiment on 200 participants with the aim of inferring and representing the conceptual storage structure of the natural category of animals as a network. This was done by formulating a statistical framework for co-occurring concepts that aims to infer significant concept–concept associations and represent them as a graph. The resulting network was analyzed and enriched by means of a missing links recovery criterion based on modularity. Both network models were compared to a thresholded co-occurrence approach. They were evaluated using a random subset of verbal fluency tests and comparing the network outcomes (linked pairs are clustering transitions and disconnected pairs are switching transitions) to the outcomes of two expert human raters. Results show that the network models proposed in this study overcome a thresholded co-occurrence approach, and their outcomes are in high agreement with human evaluations. Finally, the interplay between conceptual structure and retrieval mechanisms is discussed.
Abstract
BACKGROUND:
There is evidence in the literature supporting that fluorescent tissue signal in fluorescence-guided surgery extends farther than tissue highlighted in gadolinium in T1 sequence ...magnetic resonance imaging (MRI), which is the standard to quantify the extent of resection.
OBJECTIVE:
To study whether the presence of residual fluorescent tissue after surgery carries a different prognosis for glioblastoma (GBM) cases with complete resection confirmed by MRI.
METHODS:
A retrospective review in our center found 118 consecutive patients with high-grade gliomas operated on with the use of fluorescence-guided surgery with 5-aminolevulinic acid. Within that series, the 52 patients with newly diagnosed GBM and complete resection of enhancing tumor (CRET) in early MRI were selected for analysis. We studied the influence of residual fluorescence in the surgical field on overall survival and neurological complication rate. Multivariate analysis included potential relevant factors: age, Karnofsky Performance Scale, O6-methylguanine methyltransferase methylation promoter status, tumor eloquent location, preoperative tumor volume, and adjuvant therapy.
RESULTS:
The median overall survival was 27.0 months (confidence interval = 22.4-31.6) in patients with nonresidual fluorescence (n = 25) and 17.5 months (confidence interval = 12.5-22.5) for the group with residual fluorescence (n = 27) (P = .015). The influence of residual fluorescence was maintained in the multivariate analysis with all covariables, hazard ratio = 2.5 (P = .041). The neurological complication rate was 18.5% in patients with nonresidual fluorescence and 8% for the group with residual fluorescence (P = .267).
CONCLUSION:
GBM patients with CRET in early MRI and no fluorescent residual tissue had longer overall survival than patients with CRET and residual fluorescent tissue.
The Human Proteome Project (HPP) aims deciphering the complete map of the human proteome. In the past few years, significant efforts of the HPP teams have been dedicated to the experimental detection ...of the missing proteins, which lack reliable mass spectrometry evidence of their existence. In this endeavor, an in depth analysis of shotgun experiments might represent a valuable resource to select a biological matrix in design validation experiments. In this work, we used all the proteomic experiments from the NCI60 cell lines and applied an integrative approach based on the results obtained from Comet, Mascot, OMSSA, and X!Tandem. This workflow benefits from the complementarity of these search engines to increase the proteome coverage. Five missing proteins C-HPP guidelines compliant were identified, although further validation is needed. Moreover, 165 missing proteins were detected with only one unique peptide, and their functional analysis supported their participation in cellular pathways as was also proposed in other studies. Finally, we performed a combined analysis of the gene expression levels and the proteomic identifications from the common cell lines between the NCI60 and the CCLE project to suggest alternatives for further validation of missing protein observations.
Resection control in brain tumor surgery can be achieved in real time with intraoperative MRI (iMRI). Arterial spin labeling (ASL), a technique that measures cerebral blood flow (CBF) non‐invasively ...without the use of intravenous contrast agents, can be performed intraoperatively, providing morpho‐physiological information. This study aimed to evaluate the feasibility, image quality and potential to depict residual tumor of a pseudo‐continuous ASL (PCASL) sequence at 3 T. Seventeen patients with brain tumors, primary (16) or metastatic (1), undergoing resection surgery with iMRI monitoring, were prospectively recruited (nine men, age 56 ± 16.6 years). A PCASL sequence with long labeling duration (3000 ms) and postlabeling delay (2000 ms) was added to the conventional protocol, which consisted of pre‐ and postcontrast 3D T1‐weighted (T1w) images, optional 3D‐FLAIR, and diffusion. Three observers independently assessed the image quality (four‐point scale) of PCASL‐derived CBF maps. In those with diagnostic quality (Scores 2–4) they evaluated the presence of residual tumor using the conventional sequences first, and the CBF maps afterwards (three‐point scale). Inter‐observer agreement for image quality and the presence of residual tumor was assessed using Fleiss kappa statistics. The intraoperative CBF ratio of the surgical margins (i.e., perilesional CBF values normalized to contralateral gray matter CBF) was compared with preoperative CBF ratio within the tumor (Wilcoxon's test). Diagnostic ASL image quality was observed in 94.1% of patients (interobserver Fleiss κ = 0.76). PCASL showed additional foci suggestive of high‐grade residual component in three patients, and a hyperperfused area extending outside the enhancing component in one patient. Interobserver agreement was almost perfect in the evaluation of residual tumor with the conventional sequences (Fleiss κ = 0.92) and substantial for PCASL (Fleiss κ = 0.80). No significant differences were found between pre and intraoperative CBF ratios (p = 0.578) in patients with residual tumor (n = 7). iMRI‐PCASL perfusion is feasible at 3 T and is useful for the intraoperative assessment of residual tumor, providing in some cases additional information to the conventional sequences.
Intraoperative PCASL was assessed at 3 T. In three patients, PCASL depicted high‐CBF foci indicating additional residual components, and in one patient, PCASL showed better delineation of the residual tumor, compared with anatomical images. A 62‐year‐old male presented a tumor with peripheral irregular contrast enhancement and hyperperfusion surrounding necrosis (AP: Grade 4 glioblastoma, IDH‐1 wild type). A nodular contrast‐enhancing component on the cavity's posterior wall was depicted with conventional sequences, with no hyperperfusion. A spot of high‐CBF on PCASL was suggestive of another residual component.
To assess the association between the thickness of the retinal nerve fiber layer (RNFL), assessed by optical coherence tomography (OCT), retinal periphlebitis (RP), and multiple sclerosis (MS) ...disease activity.
We studied a prospective cohort of 61 patients and 29 matched controls for 2 years, performing a neurologic assessment every 3 months and an ophthalmologic evaluation, including OCT scans, every 6 months. Baseline MRI studies were also carried out from which brain volume and lesion load were assessed.
We found that the RNFL thickness in patients with MS was thinner than in controls, particularly in the temporal quadrant (p = 0.004). Although RNFL atrophy was greater in patients who also had optic neuritis (p = 0.002), it also augmented in MS patients who did not have optic neuritis compared with controls (p = 0.014). RNFL atrophy was correlated with greater disability (r = -0.348, p = 0.001) and longer disease duration (r = -0.301, p = 0.003). Furthermore, baseline temporal quadrant RNFL atrophy was associated with the presence of new relapses and changes in the Expanded Disability Status Scale by the end of the study (p < 0.05 in all cases). Indeed, RNFL thickness was correlated with white matter volume (r = 0.291, p = 0.005) and gray matter volume (r = 0.239, p = 0.021). The presence of RP was a risk factor for having new relapses in the next 2 years (odds ratio = 1.52, p = 0.02), and patients with RP had larger gadolinium-enhancing lesions volume (p = 0.003).
Retinal nerve fiber layer atrophy and the presence of retinal periphlebitis are associated with disease activity, suggesting that retinal evaluation can be used as biomarkers of multiple sclerosis activity.
The identification of factors associated with perioperative red blood cell (RBC) transfusion provides an opportunity to optimize the patient and surgical plan, and to guide perioperative crossmatch ...and RBC orders. We examined the association among potential bleeding risk factors and RBC requirements to develop a novel predictive model for RBC transfusion in patients undergoing brain tumor surgery.
This retrospective study included 696 adults who underwent brain tumor surgery between 2008 and 2018. Multivariable logistic regression with backward stepwise selection for predictor selection was used during modeling. Model performance was evaluated using area under the receiver operating characteristic curve, and calibration was evaluated with Hosmer-Lemeshow goodness-of-fit χ 2 -estimate.
Preoperative hemoglobin level was inversely associated with the probability of RBC transfusion (odds ratio OR: 0.50; 95% confidence interval CI: 0.39-0.63; P <0.001). The need for RBC transfusion was also greater in patients who had a previous craniotomy (OR: 2.71; 95% CI: 1.32-5.57; P =0.007) and in those with larger brain tumor volume (OR: 1.01; 95% CI: 1.00-1.02; P =0.009). The relationship between number of planned craniotomy sites and RBC transfusion was not statistically significant (OR: 2.11; 95% CI: 0.61-7.32; P =0.238). A predictive model for RBC requirements was built using these 4 variables. The area under the receiver operating characteristic curve was 0.79 (95% CI: 0.70-0.87; P <0.001) showing acceptable calibration for predicting RBC transfusion requirements.
RBC requirements in patients undergoing brain tumor surgery can be estimated with acceptable accuracy using a predictive model based on readily available preoperative clinical variables. This predictive model could help to optimize both individual patients and surgical plans, and to guide perioperative crossmatch orders.
A 52-year-old man presented with left hemifacial spasm (HFS). A magnetic resonance imaging scan showed compression of the left facial nerve at the cerebellopontine angle by a dolichoectatic basilar ...artery. The neurotological evaluation showed an otolithic deficit, with canalicular preservation and normal hearing. The deficit improved after surgical decompression. No previous report has described the impairment of vestibular function in patients presenting with HFS.
Working memory relies on information processing by several well-identified gray matter regions. However, the white matter regions and pathways involved in this cognitive process remain unknown. An ...attractive and underexplored approach to study white matter connectivity in cognitive functions is through the use of non-aprioristic models, which specifically search disrupted white matter pathways. For this purpose, we used voxel-based lesion-function mapping to correlate white matter lesions on the magnetic resonance images of 54 multiple sclerosis patients with their performance on a verbal working memory task. With this approach, we have identified critical white matter regions involved in verbal working memory in humans. They are located in the cingulum, parieto-frontal pathways and thalamo-cortical projections, with a left-sided predominance, as well as the right cerebellar white matter. Our study provides direct evidence on the white matter pathways subserving verbal working memory in the human brain.
Resection control in brain tumor surgery can be achieved in real time with intraoperative MRI (iMRI). Arterial spin labeling (ASL), a technique that measures cerebral blood flow (CBF) non‐invasively ...without the use of intravenous contrast agents, can be performed intraoperatively, providing morpho‐physiological information. This study aimed to evaluate the feasibility, image quality and potential to depict residual tumor of a pseudo‐continuous ASL (PCASL) sequence at 3 T. Seventeen patients with brain tumors, primary (16) or metastatic (1), undergoing resection surgery with iMRI monitoring, were prospectively recruited (nine men, age 56 ± 16.6 years). A PCASL sequence with long labeling duration (3000 ms) and postlabeling delay (2000 ms) was added to the conventional protocol, which consisted of pre‐ and postcontrast 3D T1‐weighted (T1w) images, optional 3D‐FLAIR, and diffusion. Three observers independently assessed the image quality (four‐point scale) of PCASL‐derived CBF maps. In those with diagnostic quality (Scores 2–4) they evaluated the presence of residual tumor using the conventional sequences first, and the CBF maps afterwards (three‐point scale). Inter‐observer agreement for image quality and the presence of residual tumor was assessed using Fleiss kappa statistics. The intraoperative CBF ratio of the surgical margins (i.e., perilesional CBF values normalized to contralateral gray matter CBF) was compared with preoperative CBF ratio within the tumor (Wilcoxon's test). Diagnostic ASL image quality was observed in 94.1% of patients (interobserver Fleiss κ = 0.76). PCASL showed additional foci suggestive of high‐grade residual component in three patients, and a hyperperfused area extending outside the enhancing component in one patient. Interobserver agreement was almost perfect in the evaluation of residual tumor with the conventional sequences (Fleiss κ = 0.92) and substantial for PCASL (Fleiss κ = 0.80). No significant differences were found between pre and intraoperative CBF ratios (p = 0.578) in patients with residual tumor (n = 7). iMRI‐PCASL perfusion is feasible at 3 T and is useful for the intraoperative assessment of residual tumor, providing in some cases additional information to the conventional sequences.
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