The Role of MicroRNAs in Proteostasis Decline and Protein Aggregation during Brain and Skeletal Muscle Aging

Aging can be defined as the progressive deterioration of cellular, tissue, and organismal function over time. Alterations in protein homeostasis, also known as proteostasis, are a hallmark of aging that lead to proteome imbalances and protein aggregation, phenomena that also occur in age-related diseases. Among the various proteostasis regulators, microRNAs (miRNAs) have been reported to play important roles in the post-transcriptional control of genes involved in maintaining proteostasis during the lifespan in several organismal tissues. In this review, we consolidate recently published reports that demonstrate how miRNAs regulate fundamental proteostasis-related processes relevant to tissue aging, with emphasis on the two most studied tissues, brain tissue and skeletal muscle. We also explore an emerging perspective on the role of miRNA regulatory networks in age-related protein aggregation, a known hallmark of aging and age-related diseases, to elucidate potential miRNA candidates for anti-aging diagnostic and therapeutic targets.

Integration of segmented regression analysis with weighted gene correlation network analysis identifies genes whose expression is remodeled throughout physiological aging in mouse tissues

Gene expression alterations occurring with aging have been described for a multitude of species, organs, and cell types. However, most of the underlying studies rely on static comparisons of mean gene expression levels between age groups and do not account for the dynamics of gene expression throughout the lifespan. These studies also tend to disregard the pairwise relationships between gene expression profiles, which may underlie commonly altered pathways and regulatory mechanisms with age. To overcome these limitations, we have combined segmented regression analysis with weighted gene correlation network analysis (WGCNA) to identify high-confidence signatures of aging in the brain, heart, liver, skeletal muscle, and pancreas of C57BL/6 mice in a publicly available RNA-Seq dataset (GSE132040). Functional enrichment analysis of the overlap of genes identified in both approaches showed that immune- and inflammation-related responses are prominently altered in the brain and the liver, while in the heart and the muscle, aging affects amino and fatty acid metabolism, and tissue regeneration, respectively, which reflects an age-related global loss of tissue function. We also explored sexual dimorphism in the aging mouse transcriptome and found the liver and the muscle to have the most pronounced gender differences in gene expression throughout the lifespan, particularly in proteostasis-related pathways. While the data showed little overlap among the age-dysregulated genes between tissues, aging triggered common biological processes in distinct tissues, which we highlight as important features of murine tissue physiological aging.

The diagnosis of delirium in 80 emergency unit patients

We evaluated the initial and final diagnosis of 80 patients with delirium arriving at the emergence unit of a university hospital in a large Brazilian city over a period of 30 months up to December 1991. The diagnosis was based on the DSM-IIIR criteria. Patients with a known history of head trauma or epileptic seizure and patients younger than 13 years were excluded. Only patients with a disease of up to 7 days were included. The patients were subdivided into four etiologic groups: vascular; associated with the use of alcohol; infectious-parasitic; miscellaneous. The results showed a rate of correct diagnosis ranging from 65 to 80% with the use of kappa test (standard good to excellent). Sensitivity, specificity, positive predictive and negative predictive values had results showing different conditions for initial diagnosis in each group. This study can help the initial diagnosis of delirium and the choice for diagnostic testing.

[Subarachnoidal hemorrhage with cranial tomography without bleeding signals]

We observed 23 patients with clinical hypothesis of subarachnoidal hemorrhage (SAH) having cranial tomography (CT) without bleeding signals. The final diagnosis of SAH was made upon the cerebrospinal fluid (CSF) results. Twenty cases were submitted to brain angiography. They were focused under the clinical classification of Hunt & Hess. The main results were 1) 1/3 of patients had interval time between 24 and 48 hours after ictus and before CT and CSF making; this was the most sensitive CT time; 2) 55% of patients with brain angiography had aneurysm predominantly in the carotid and anterior cerebral artery territory; 3) the dominant clinical degree was Hunt & Hess I e II.

CONCLUSION

the results demonstrate the need of CSF test in case of SAH clinical diagnosis with CT showing no bleeding signals.

Immunoglobulin A nephropathy in a renal allograft of a black transplant recipient

Although IgA nephropathy (IgA N) is reportedly the most common form of primary glomerulonephritis worldwide, there is a very low incidence of IgA N in Black Americans, and IgA N in Black patients with renal allografts has not been reported. In this report, we present the case of a Black patient with endstage renal disease presumed secondary to hypertensive nephrosclerosis who developed nephrotic range proteinuria due to IgA N in a cadaveric renal allograft 2 years following transplantation. Biopsy of the allograft in the immediate post-transplantation period had revealed no evidence of IgA N. Chronic active hepatitis related to hepatitis C preceded the development of proteinuria by approximately 1 year, raising the possibility that IgA N in the renal allograft was secondary to the liver disease. The clinical and histological features of primary IgA N and IgA N secondary to liver diseases are discussed.