Preoperative Age and Its Impact on Long-Term Renal Functional Decline after Robotic-Assisted Partial Nephrectomy: Insights from a Tertiary Referral Center.

Background and Objectives: to investigate the impact of age on renal function deterioration after robotic-assisted partial nephrectomy (RAPN) focusing on a decline to moderate and severe forms of chronic kidney disease (CKD). Materials and Methods: This is a single center prospective analysis of patients who underwent RAPN. The outcomes include the development of de novo CKD-S 3a [estimated glomerular filtration rate (eGFR) < 60 mL/min/1.73 m2)] and de novo CKD-S 3b (eGFR < 45 mL/min/1.73/m2). Multivariable analysis (MVA) via Cox regression identified predictors for CKD-S 3a/b. Kaplan -Meier Analyses (KMA) were fitted for survival assessment. Multivariable linear regression was utilized to identify the predictors of last-eGFR. Results: Overall, 258 patients were analyzed [low age (<50) n = 40 (15.5%); intermediate age (50-70) n = 164 (63.5%); high age (>70) n = 54 (20.9%)] with a median follow-up of 31 (IQR 20-42) months. MVA revealed an increasing RENAL score [Hazard Ratio (HR) 1.32, p = 0.009], age 50-70 (HR 6.21, p = 0.01), age ≥ 70 (HR 10.81, p = 0.001), increasing BMI (HR 1.11, p < 0.001) and preoperative CKD 2 (HR 2.43, p = 0.014) are independent risk factors associated with an increased risk of CKD-S 3a; conversely, post-surgical acute kidney injury was not (p = 0.83). MVA for CKD-S 3b revealed an increasing RENAL score (HR 1.51, p = 0.013) and age ≥ 70 (HR 2.73, p = 0.046) are associated with an increased risk of CKD-S 3b. Linear regression analysis revealed increasing age (Coeff. -0.76, p < 0.001), increasing tumor size (Coeff. -0.31, p = 0.03), and increasing BMI (Coeff. -0.64, p = 0.004) are associated with decreasing eGFR at last follow-up. We compare the survival distribution of our cohort stratified by age elderly patients experienced worsened CKD-S 3a/b disease-free survival (p < 0.001; p < 0.001, respectively). Conclusions: Age is independently associated with a greater risk of significant and ongoing decline in kidney function following RAPN. Recognizing the impact of aging on renal function post-surgery can guide better management practices. Further investigations are required.

Error-prone protein synthesis recapitulates early symptoms of Alzheimer disease in aging mice.

Age-related neurodegenerative diseases (NDDs) are associated with the aggregation and propagation of specific pathogenic protein species (e.g., Aß, α-synuclein). However, whether disruption of synaptic homeostasis results from protein misfolding per se rather than accumulation of a specific rogue protein is an unexplored question. Here, we show that error-prone translation, with its frequent outcome of random protein misfolding, is sufficient to recapitulate many early features of NDDs, including perturbed Ca2+ signaling, neuronal hyperexcitability, and mitochondrial dysfunction. Mice expressing the ribosomal ambiguity mutation Rps9 D95N exhibited disrupted synaptic homeostasis resulting in behavioral changes reminiscent of early Alzheimer disease (AD), such as learning and memory deficits, maladaptive emotional responses, epileptiform discharges, suppressed circadian rhythmicity, and sleep fragmentation, accompanied by hippocampal NPY expression and cerebral glucose hypometabolism. Collectively, our findings suggest that random protein misfolding may contribute to the pathogenesis of age-related NDDs, providing an alternative framework for understanding the initiation of AD.

Premature aging in mice with error-prone protein synthesis.

The main source of error in gene expression is messenger RNA decoding by the ribosome. Translational accuracy has been suggested on a purely correlative basis to positively coincide with maximum possible life span among different rodent species, but causal evidence that translation errors accelerate aging in vivo and limit life span is lacking. We have now addressed this question experimentally by creating heterozygous knock-in mice that express the ribosomal ambiguity mutation RPS9 D95N, resulting in genome-wide error-prone translation. Here, we show that Rps9 D95N knock-in mice exhibit reduced life span and a premature onset of numerous aging-related phenotypes, such as reduced weight, chest deformation, hunchback posture, poor fur condition, and urinary syndrome, together with lymphopenia, increased levels of reactive oxygen species-inflicted damage, accelerated age-related changes in DNA methylation, and telomere attrition. Our results provide an experimental link between translational accuracy, life span, and aging-related phenotypes in mammals.

ER-misfolded proteins become sequestered with mitochondria and impair mitochondrial function.

Proteostasis is a challenge for cellular organisms, as all known protein synthesis machineries are error-prone. Here we show by cell fractionation and microscopy studies that misfolded proteins formed in the endoplasmic reticulum can become associated with and partly transported into mitochondria, resulting in impaired mitochondrial function. Blocking the endoplasmic reticulum-mitochondria encounter structure (ERMES), but not the mitochondrial sorting and assembly machinery (SAM) or the mitochondrial surveillance pathway components Msp1 and Vms1, abrogated mitochondrial sequestration of ER-misfolded proteins. We term this mitochondria-associated proteostatic mechanism for ER-misfolded proteins ERAMS (ER-associated mitochondrial sequestration). We testify to the relevance of this pathway by using mutant α-1-antitrypsin as an example of a human disease-related misfolded ER protein, and we hypothesize that ERAMS plays a role in pathological features such as mitochondrial dysfunction.

Ribosomal mistranslation leads to silencing of the unfolded protein response and increased mitochondrial biogenesis.

Translation fidelity is the limiting factor in the accuracy of gene expression. With an estimated frequency of 10-4, errors in mRNA decoding occur in a mostly stochastic manner. Little is known about the response of higher eukaryotes to chronic loss of ribosomal accuracy as per an increase in the random error rate of mRNA decoding. Here, we present a global and comprehensive picture of the cellular changes in response to translational accuracy in mammalian ribosomes impaired by genetic manipulation. In addition to affecting established protein quality control pathways, such as elevated transcript levels for cytosolic chaperones, activation of the ubiquitin-proteasome system, and translational slowdown, ribosomal mistranslation led to unexpected responses. In particular, we observed increased mitochondrial biogenesis associated with import of misfolded proteins into the mitochondria and silencing of the unfolded protein response in the endoplasmic reticulum.

Modification at the 2'-Position of the 4,5-Series of 2-Deoxystreptamine Aminoglycoside Antibiotics To Resist Aminoglycoside Modifying Enzymes and Increase Ribosomal Target Selectivity.

A series of derivatives of the 4,5-disubstituted class of 2-deoxystreptamine aminoglycoside antibiotics neomycin, paromomycin, and ribostamycin was prepared and assayed for (i) their ability to inhibit protein synthesis by bacterial ribosomes and by engineered bacterial ribosomes carrying eukaryotic decoding A sites, (ii) antibacterial activity against wild type Gram negative and positive pathogens, and (iii) overcoming resistance due to the presence of aminoacyl transferases acting at the 2'-position. The presence of five suitably positioned residual basic amino groups was found to be necessary for activity to be retained upon removal or alkylation of the 2'-position amine. As alkylation of the 2'-amino group overcomes the action of resistance determinants acting at that position and in addition results in increased selectivity for the prokaryotic over eukaryotic ribosomes, it constitutes an attractive modification for introduction into next generation aminoglycosides. In the neomycin series, the installation of small (formamide) or basic (glycinamide) amido groups on the 2'-amino group is tolerated.