Hemato-encephalic barriers. Morphologic data

Within the cranio-spinal cavity we can consider three compartments: blood, cerebro-spinal fluid and nervous parenchyma and thus, three barriers (Blood-Cerebro-Spinal Fluid, Blood-Brain, Cerebro-Spinal Fluid-Brain). The morphological studies of these barriers were performed with exogenous tracers such as horseradish peroxidase, cytochrome C and ferritin or endogenous tracers such as autologous antiperoxidase immunoglobulins. 1. The blood-brain barrier is exogenous and endogenous tracers proof. It is found on the level of the brain capillary endothelium with tight junctions and rare plasmalemmal vesicles. 2. The blood-cerebro-spinal fluid barrier is found on the level of choroid plexus and of leptomeningeal vessel. In the former, the tracer is stopped by the tight junctions (zonula occludens type) of the choroid plexus epithelium. Besides, there is no morphological evidence of transepithelial passage from blood to cerebro-spinal fluid. In the later, the barrier is, almost always, found on the level of the vascular endothelium. 3. The parenchymatous-cerebro-spinal fluid interface cannot be called a barrier because the diffusion of the tracers is not restricted either by the astrocytic marginal layer or by the ependyma. The circumventricular organs other than choroid plexus are morphologically characterized by the free diffusion of tracers in their perivascular connective space. Subcommissural organs capillaries alone behave like those of the brain. The spinal cord capillaries, in opposition to those of the brain, are characterized by a perivascular connective space, for 40 p. 100 of them. The significance of this fact is still unknown.     

Virtual text and the growth of meaning in qualitative analysis

Qualitative researchers frequently analyze data in the form of narrative, such as responses to open-ended interview questions. Researchers acknowledge the validity of more than one interpretation of the same narratives but, to date, have offered little justification for multiple valid interpretations. A concept from literary theory, “the virtual text,” is presented to help explain the mechanism of multiple interpretations and provide a justification for their validity. An example from the first author's research is provided. © 1996 John Wiley & Sons, Inc.     

Tractostorm 2: Optimizing tractography dissection reproducibility with segmentation protocol dissemination

The segmentation of brain structures is a key component of many neuroimaging studies. Consistent anatomical definitions are crucial to ensure consensus on the position and shape of brain structures, but segmentations are prone to variation in their interpretation and execution. White‐matter (WM) pathways are global structures of the brain defined by local landmarks, which leads to anatomical definitions being difficult to convey, learn, or teach. Moreover, the complex shape of WM pathways and their representation using tractography (streamlines) make the design and evaluation of dissection protocols difficult and time‐consuming. The first iteration of Tractostorm quantified the variability of a pyramidal tract dissection protocol and compared results between experts in neuroanatomy and nonexperts. Despite virtual dissection being used for decades, in‐depth investigations of how learning or practicing such protocols impact dissection results are nonexistent. To begin to fill the gap, we evaluate an online educational tractography course and investigate the impact learning and practicing a dissection protocol has on interrater (groupwise) reproducibility. To generate the required data to quantify reproducibility across raters and time, 20 independent raters performed dissections of three bundles of interest on five Human Connectome Project subjects, each with four timepoints. Our investigation shows that the dissection protocol in conjunction with an online course achieves a high level of reproducibility (between 0.85 and 0.90 for the voxel‐based Dice score) for the three bundles of interest and remains stable over time (repetition of the protocol). Suggesting that once raters are familiar with the software and tasks at hand, their interpretation and execution at the group level do not drastically vary. When compared to previous work that used a different method of communication for the protocol, our results show that incorporating a virtual educational session increased reproducibility. Insights from this work may be used to improve the future design of WM pathway dissection protocols and to further inform neuroanatomical definitions.     

Erythrocyte antioxidant activity in human patients with Parkinson's disease

Three groups have reported defective antioxidant mechanisms in substantia nigra of patients with Parkinson's disease, namely a decreased catalase and peroxidase activity, a reduction of glutathione and, more recently, a diminished nigral glutathione peroxidase activity. We decided to investigate these mechanisms in erythrocytes to determine whether these brain defects represent generalized or genetic aberrations, in which case they should also be present in blood cells. The glutathione cycle has been investigated (reduced and oxidized glutathione, glutathione reductase and peroxidase) plus the activities of catalase and superoxide dismutase. The basal malonaldehyde content of erythrocytes was used as an index of endogenous lipid peroxidation. None of the above-mentioned parameters were found altered in erythrocytes of parkinsonians, suggesting that no genetic or generalized biochemical abnormalities underly the deficiencies detected in substantia nigra.     

Aspergillosis of ethmoid sinus and optic nerve, with arteritis and rupture of the internal carotid artery

A 54-year-old woman had been treated 26 years previously for Hodgkin's disease. Eight months before presentation, the disease had recurred and the patient had received cytotoxic drugs and steroids. She presented with loss of vision of the right eye and died 5 months later from extensive subarachnoid hemorrhage. Postmortem examination revealed an aspergillus abscess of the ethmoid sinus, extending to the right frontal lobe and optic nerve, and to the wall of the right internal carotid artery (ICA). Death was due to rupture of the ICA. Such a presentation of aspergillosis is unusual. Three cases of aspergillus arteritis causing rupture of the ICA have been reported previously.     

Ghrelin levels are associated with hunger as measured by the Three-Factor Eating Questionnaire in healthy young adults

Weight gain and appetite regulation are complex interplays between internal and external cues. Our aim was to investigate the association of eating behaviors with ghrelin taking into account lifestyle. We conducted a cross-sectional analysis in a sample of first-year university students at the Université de Sherbrooke. We collected medical history, anthropometric measurements, vital signs, fitness index, and fasting blood samples. Questionnaires included a lifestyle questionnaire and the Three-Factor Eating Questionnaire (TFEQ) estimating dietary restraint, disinhibition and hunger. We recruited 308 participants aged 20.7 ± 3.2 years and a mean BMI of 23.3 ± 3.4 kg/m². Hunger score was significantly associated with ghrelin levels (r = 0.11, P < 0.05). In women, this association was independent of age, BMI, dietary and lifestyle factors (P = 0.02). The association between ghrelin level and hunger score was observable in leaner individuals (r = 0.28, p < 0.0001) but not in heavier individuals (r = − 0.08, p = 0.34; stratified by BMI < vs > 22.6 kg/m²). Restraint (R) and disinhibition (D) were not associated with ghrelin levels. The three eating behaviors demonstrated expected correlations with lifestyle supporting the validity of the TFEQ in this cohort. In conclusion, we demonstrated that ghrelin, a biological marker, is associated with self-reported perception of hunger, independently of anthropometric measures and lifestyle.