Alzheimer’s disease (AD) is the leading cause of dementia in aging individuals. Yet, the pathophysiological processes involved in AD onset and progression are still poorly understood. Among numerous strategies, a comprehensive overview of gene expression alterations in the diseased brain could contribute for a better understanding of the AD pathology. In this work, we probed the differential expression of genes in different brain regions of healthy and AD adult subjects using data from three large transcriptomic studies: Mayo Clinic, Mount Sinai Brain Bank (MSBB), and ROSMAP. Using a combination of differential expression of gene and isoform switch analyses, we provide a detailed landscape of gene expression alterations in the temporal and frontal lobes, harboring brain areas affected at early and late stages of the AD pathology, respectively. Next, we took advantage of an indirect approach to assign the complex gene expression changes revealed in bulk RNAseq to individual cell types/subtypes of the adult brain. This strategy allowed us to identify previously overlooked gene expression changes in the brain of AD patients. Among these alterations, we show isoform switches in the AD causal gene amyloid-beta precursor protein (APP) and the risk gene bridging integrator 1 (BIN1), which could have important functional consequences in neuronal cells. Altogether, our work proposes a novel integrative strategy to analyze RNAseq data in AD and other neurodegenerative diseases based on both gene/transcript expression and regional/cell-type specificities.

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In this study, we report a complete (clinical, radiological, and virological) sustained (1 year) response after nivolumab salvage therapy in a progressive multifocal leukoencephalopathy patient. Analyses of the cells infiltrate in a pretreatment brain biopsy suggest that parenchymal programmed cell death-L1+ macrophages could be the T-cells partnership in immune exhaustion and virus escape.

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Alzheimer's disease (AD) is characterized by intracerebral accumulations of extracellular amyloid-β (Aβ) plaques and intracellular tau pathology that spread in the brain. Three types of tau lesions occur in the form of neuropil threads, neurofibrillary tangles, and neuritic plaques i.e. tau aggregates within neurites surrounding Aβ deposits. The cascade of events linking these lesions and synaptic or memory impairments are still debated. Intracerebral infusion of human AD brain extracts in Aβ plaque-bearing mice that do not overexpress pathological tau proteins induces tau pathologies following heterotopic seeding of mouse tau protein. There is however little information regarding the downstream events including synaptic or cognitive repercussions of tau pathology induction in these models. In the present study, human AD brain extracts (ADbe) and control-brain extracts (Ctrlbe) were infused into the hippocampus of Aβ plaque-bearing APPswe/PS1dE9 mice. Memory, synaptic density, as well as Aβ plaque and tau aggregate loads, microgliosis, astrogliosis at the inoculation site and in connected regions (perirhinal/entorhinal cortex) were evaluated 4 and 8 months post-inoculation. ADbe inoculation produced the following effects: (i) memory deficit; (ii) increased Aβ plaque deposition in proximity to the inoculation site; (iii) tau pathology induction; (iv) appearance of neuropil threads and neurofibrillary tangles next to the inoculation site with a spreading to connected regions. Neuritic plaque pathology was detected in both ADbe- and Ctrlbe-inoculated animals but ADbe inoculation increased the severity close to and at distance of the inoculation site. (v) Finally, ADbe inoculation reduced synaptic density in the vicinity to the inoculation site and in connected regions as the perirhinal/entorhinal cortex. Synaptic impairments were correlated with increased severity of neuritic plaques but not to other tau lesions or Aβ lesions, suggesting that neuritic plaques are a culprit for synaptic loss. Synaptic density was also associated with microglial load. Graphical abstract

Age estimation of living individuals is a regular activity in medico-legal practice. Among the available tools for determining skeletal age, some authors have stated that the disappearance of epiphyseal scars could be a useful marker. The aim of the present study was to assess whether the presence of an epiphyseal scar on the knee, as seen on a plain X-ray, was linked to biological age. A total of 988 frontal X-rays of individuals (509 females and 479 males) aged between 15 and 40 years were analyzed to see whether a scar was visible or not on each of the three epiphyses of the knee. A scar was visible for 96% of the females and 98% of the males. For each sex, scars were visible at each year of age, from 15 to 40 years. In younger females, there were 15 individuals with no scar visible on the fibula, 16 on the tibia, and 20 on the femur. For males, the ages were respectively 16, 17, and 18 years. On a frontal X-ray, the persistence of epiphyseal scars was not a marker of a recent fusion. All individuals with fully ossified knee that had no scar on the femur were older than 18 years. Further studies focusing on epiphyseal scars on MR and CT scans could be useful, as these techniques allow the more precise analysis of the epiphysis.

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We report the case of a 5-year-old boy who died from complications of rheumatic heart disease with atypical presentation. He was hospitalized for recent inflammatory and neurological symptoms. He was diagnosed with viral encephalitis. He died the day after he was discharged. The macroscopic autopsy findings were unremarkable. Histology revealed typical rheumatic heart disease. Neuropathology showed cerebral infarction due to an embolic event linked with the rheumatic valvulitis. The cause of death was determined as heart failure due to rheumatic heart disease secondary to an undiagnosed acute rheumatic fever. It is related to an autoimmune response to infection with group A streptococcus. It mainly affects children in developing countries. In our case, viral encephalitis was consistent with the medical history and the proper diagnosis was made on histological analysis. Forensic pathologists should consider this diagnosis facing a sudden unexpected death in childhood, even in industrialized countries.