Defective hippocampal neurogenesis underlies cognitive impairment by carotid stenosis-induced cerebral hypoperfusion in mice

Chronic cerebral hypoperfusion due to carotid artery stenosis is a major cause of vascular cognitive impairment and dementia (VCID). Bilateral carotid artery stenosis (BCAS) in rodents is a well-established model of VCID where most studies have focused on white matter pathology and subsequent cognitive deficit. Therefore, our aim was to study the implication of adult hippocampal neurogenesis in hypoperfusion-induced VCID in mice, and its relationship with cognitive hippocampal deficits. Mice were subjected to BCAS; 1 and 3 months later, hippocampal memory and neurogenesis/cell death were assessed, respectively, by the novel object location (NOL) and spontaneous alternation performance (SAP) tests and by immunohistology. Hypoperfusion was assessed by arterial spin labeling-magnetic resonance imaging (ASL-MRI). Hypoperfused mice displayed spatial memory deficits with decreased NOL recognition index. Along with the cognitive deficit, a reduced number of newborn neurons and their aberrant morphology indicated a remarkable impairment of the hippocampal neurogenesis. Both increased cell death in the subgranular zone (SGZ) and reduced neuroblast proliferation rate may account for newborn neurons number reduction. Our data demonstrate quantitative and qualitative impairment of adult hippocampal neurogenesis disturbances associated with cerebral hypoperfusion-cognitive deficits in mice. These findings pave the way for novel diagnostic and therapeutic targets for VCID.

Analysis of urinary exosomal metabolites identifies cardiovascular risk signatures with added value to urine analysis

BACKGROUND

Subclinical atherosclerosis may result in fatal cardiovascular (CV) events, but the underlying mechanisms and molecular players leading to disease are not entirely understood. Thus, novel approaches capable of identifying the factors involved in pathological progression and providing a better understanding of the subjacent mechanisms are needed. Extracellular vesicles (EVs) have been shown to have numerous biological functions, and their metabolome has recently generated interest as a source of novel biomarkers. The metabolic content of the exosomes has been so far unexplored in cardiovascular disease (CVD), and here, we developed an analytical strategy aimed at probing urinary exosomal metabolite content and its association to CV risk.

RESULTS

Direct analysis of the exosomes without metabolite extraction was evaluated by high-resolution magic angle spinning (¹H HR-MAS). Other two methodologies for the analysis of exosomal metabolites by ¹H NMR were set up, based on methanol or organic solvents sequential extraction. The three methods were compared in terms of the number of detected signals and signal to noise ratio (S/N). The methanol method was applied to identify altered metabolites in the urinary exosomes of subjects with programmed coronary artery by-pass grafting (CABG) versus a control group. Target mass spectrometry (MS) was also performed for differential analysis. The clinical performance of exosomal metabolites of interest in CVD was investigated, and the added value of the exosomes compared to urine analysis was evaluated. Based on S/N ratio, simplicity, reproducibility, and quality of the spectrum, the methanol method was chosen for the study in CVD. A cardiometabolic signature composed by 4-aminohippuric acid, N-1-methylnicotinamide, and citric acid was identified in urinary exosomes. Directly in urine, 4-aminohippuric acid and citric acid do not show variation between groups and changes in N-1-methylnicotinamide are less pronounced, proving the added value of exosomes.

CONCLUSIONS

We set up a novel methodology to analyze metabolic alterations in urinary exosomes and identified a cardiometabolic signature in these microvesicles. This study constitutes the first evidence of a role for the exosomal metabolism in CVD and demonstrates the possibility to evaluate the urinary exosomal metabolic content by NMR and MS.

[Unilateral facial and cerebral hyperplasia associated with neurofibromatosis type 1. Report of four patients]

INTRODUCTION

Plexiform neurofibroma in any location is one of the commonest complications associated with neurofibromatosis type 1 (NF1). Plexiform neurofibroma of the upper eyelid and orbit is usually associated with ipsilateral hemifacial hyperplasia. We present four patients with NF1 and plexiform neurofibroma of the eyelid and orbit associated with hemifacial hyperplasia, who also showed hyperplasia of the unilateral cerebral hemisphere.

CASE REPORTS

There are four patients, three females and one male, who consulted because of NF1 with plexiform neurofibroma of upper eyelid and hemifacial hyperplasia. Upper eyelid involvement was observed since birth and progressed during the first years of life. The patients showed normal neurological and mental development without motor or cerebellar disorders. Magnetic resonance studies demonstrated the asymmetric hyperplasia of the ipsilateral hemisphere in all four cases and of the cerebellar hemisphere in one case. The degree of hemispheric hyperplasia was related to the size and extension of the plexiform neurofibroma, as well as to the severity of the hemifacial hyperplasia. In our case which had the plexiform neurofibroma extended to the neck and the upper thorax, the hyperplasia not only affected the cerebral hemisphere but also the ipsilateral cerebellar hemisphere. All parts of the hemisphere showed increased size. The cortex of the entire hemisphere showed normal differentiation of the subcortical white matter.

CONCLUSION

NF1 appears to be related with facial and cerebral ipsilateral hemihyperplasia. The relation between the size and extension of the orbital, eyelid and facial plexiform neurofibroma and the degree of asymmetry of the hemispheric hyperplasia suggest that different influences of a still unknown agent, possibly a gene, obviously related to NF1, causes both the intracranial and extracranial abnormalities.

[Glutaric aciduria type 1 with normal evolution: follow-up of one case until adult age]

We present a patient of 20 years of age with glutaric aciduria type 1 (GA1) and normal psychomotor development. Her symptoms consisted of a few convulsions between 2.5 and 4.5 years of age. She was diagnosed at 9 years of age because of the typical alterations of GA1 that appeared in computed tomography and magnetic resonance (MR) imaging studies. Enzymatic activity in fibroblasts culture was nonexistent and glutarate excretion was elevated in the annual controls where this was investigated from the diagnosis of the disease so far. MR studies showed hyposignal in T1 of the subcortical white matter, severe dilatation of the Sylvian region and temporal fossa subarachnoid spaces, and hypoplasia of the subjacent cerebral parenchyma and of both temporal lobes. The corpus callosum and the surrounding zones appeared very enlarged and with signal changes. Spectroscopic MR showed signs of membrane instability and cellular impoverishment in subcortical white matter and basal ganglia and presence of lactic acid. Macrocephaly always maintained centiles over 98. The patient has no abnormal movements or motor disturbances, her behavior and intelligence being normal and she is able to follow studies of middle level.