Angiopathie amyloïde cérébrale sporadique

[Cerebral amyloid angiopathy is difficult to diagnose in the intensive care unit]

Cerebral amyloid angiopathy is a common cause of intracerebral haemorrhage in elderly patients. The diagnosis of cerebral amyloid angiopathy is based on the Boston criteria combining clinical and radiological criteria with no other cause of intracerebral haemorrhage. We describe the case of a 60-year-old female admitted to the intensive care unit for agitation and spatial disorientation. She had multiple intracerebral haematomas on brain CT scan. Typical cerebral microbleeds using MRI and the absence of other cause of intracerebral haemorrhage argued in favour of the diagnosis of cerebral amyloid angiopathy. The patient outcome was favourable with a discharge from the intensive care unit on day 16.

Disorder-to-order conformational transitions in protein structure and its relationship to disease

Function in proteins largely depends on the acquisition of specific structures through folding at physiological time scales. Under both equilibrium and non-equilibrium states, proteins develop partially structured molecules that being intermediates in the process, usually resemble the structure of the fully folded protein. These intermediates, known as molten globules, present the faculty of adopting a large variety of conformations mainly supported by changes in their side chains. Taking into account that the mechanism to obtain a fully packed structure is considered more difficult energetically than forming partially "disordered" folding intermediates, evolution might have conferred upon an important number of proteins the capability to first partially fold and-depending on the presence of specific partner ligands-switch on disorder-to-order transitions to adopt a highly ordered well-folded state and reach the lowest energy conformation possible. Disorder in this context can represent segments of proteins or complete proteins that might exist in the native state. Moreover, because this type of disorder-to-order transition in proteins has been found to be reversible, it has been frequently associated with important signaling events in the cell. Due to the central role of this phenomenon in cell biology, protein misfolding and aberrant disorder-to-order transitions have been at present associated with an important number of diseases.

The enigma of vascular cognitive disorder and vascular dementia

The prevalence, morphology and pathogenesis of vascular dementia (VaD), recently termed vascular cognitive impairment, are a matter of discussion, and currently used clinical diagnostic criteria show moderate sensitivity (average 50%) and variable specificity (range 64-98%). In Western clinic-based series, VaD is suggested in 8-10% of cognitively impaired aged subjects. Its prevalence in autopsy series varies from 0.03 to 58%, with reasonable values of 8-15%, while in Japan it is seen in 22-35%. Neuropathologic changes associated with cognitive impairment include multifocal and/or diffuse disease and focal lesions: multi-infarct encephalopathy, white matter lesions or arteriosclerotic subcortical (leuko)encephalopathy, multilacunar state, mixed cortico-subcortical type, borderline/watershed lesions, rare granular cortical atrophy, post-ischemic encephalopathy and hippocampal sclerosis. They result from systemic, cardiac and local large or small vessel disease. Recent data indicate that cognitive decline is commonly associated with widespread small ischemic/vascular lesions (microinfarcts, lacunes) throughout the brain with predominant involvement of subcortical and functionally important brain areas. Their pathogenesis is multifactorial, and their pathophysiology affects neuronal networks involved in cognition, memory, behavior and executive functioning. Vascular lesions often coexist with Alzheimer disease (AD) and other pathologies. Minor cerebrovascular lesions, except for severe amyloid angiopathy, appear not essential for cognitive decline in full-blown AD, while both mild Alzheimer pathology and small vessel disease may interact synergistically. The lesion pattern of "pure" VaD, related to arteriosclerosis and microangiopathies, differs from that in mixed-type dementia (AD with vascular encephalopathy), more often showing large infarcts, which suggests different pathogenesis of both types of lesions. Due to the high variability of cerebrovascular pathology and its causative factors, no validated neuropathologic criteria for VaD are available, and a large variability across laboratories still exists in the procedures for morphologic examination and histology techniques.