Citations

Reactive oxygen species (ROS) and cellular oxidative stress are involved in many physiological and pathophysiological processes, including cellular and organismal aging, migration, proliferation, senescence or death of normal and cancer cells, and stress resistance of stem cells. The forkhead homeobox type O (FOXO) transcription factors FOXO1, FOXO3a, and FOXO4 are critical mediators of the cellular responses to oxidative stress and have been implicated in many of the above ROS-regulated processes. In cancer cells they converge oxidative stress signaling to cell cycle arrest and cell death or promote a motile phenotype. Dependent on their posttranslational modifications FOXOs can also actively regulate the detoxification of cells from ROS and promote stress resistance. Thus, FOXO transcription factors are of vital importance in processes regulating tumor survival or progression, stem cell maintenance, age-related pathological processes, and lifespan extension. Antioxid. Redox Signal. 14, 593–605.

OBJECTIVE The accumulation of old and damaged proteins likely contributes to complications of diabetes, but currently no methodology is available to measure the relative age of a specific protein alongside assessment of posttranslational modifications (PTM). To accomplish our goal of studying the impact of insulin deficiency and hyperglycemia in type 1 diabetes upon accumulation of old damaged isoforms of plasma apolipoprotein A-1 (ApoA-1), we sought to develop a novel methodology, which is reported here and can also be applied to other specific proteins. RESEARCH DESIGN AND METHODS To label newly synthesized proteins, [ring-13C6]phenylalanine was intravenously infused for 8 h in type 1 diabetic participants (n = 7) during both insulin treatment and 8 h of insulin deprivation and in nondiabetic participants (n = 7). ApoA-1 isoforms were purified by two-dimensional gel electrophoresis (2DGE) and assessment of protein identity, PTM, and [ring-13C6]phenylalanine isotopic enrichment (IE) was performed by tandem mass spectrometry. RESULTS Five isoforms of plasma ApoA-1 were identified by 2DGE including ApoA-1 precursor (pro-ApoA-1) that contained the relatively highest IE, whereas the older forms contained higher degrees of damage (carbonylation, deamidation) and far less IE. In type 1 diabetes, the relative ratio of IE of [ring-13C6]phenylalanine in an older isoform versus pro-ApoA-1 was higher during insulin deprivation, indicating that de novo synthesized pro-ApoA-1 more rapidly accumulated damage, converting to mature ApoA-1. CONCLUSIONS We developed a mass spectrometry–based methodology to identify the relative age of protein isoforms. The results demonstrated accelerated oxidative damage to plasma ApoA-1, thus offering a potential mechanism underlying the impact of poor glycemic control in type 1 diabetic patients that affects a patient's risk for vascular disease.

Salvage of failed total wrist arthroplasty by arthrodesis may be difficult because of bone loss and poor quality of bone and soft tissues. We examined the outcomes of wrist arthrodesis for failed total wrist arthroplasty in a retrospective study of 21 wrists in 17 patients. Clinical data, radiographs, patient-reported outcomes and DASH questionnaires were used. Thirteen women and four men had undergone total wrist arthroplasty at an average age of 55 years. The mode of failure was aseptic loosening in 13 wrists. The average time from the index arthroplasty to wrist arthrodesis was 7.6 years. Autograft and/or allograft bone graft was used in all of the wrists. Arthrodesis was achieved in 11 wrists and ten had a nonunion. Six arthrodeses underwent eight revisions for nonunion, with two achieving union. The mean DASH score was 29 in wrists that fused and 36 in those that did not fuse. Pain scores averaged 2.1 in the wrists that fused and 3.3 in the nonunion group. Most patients had clinical improvement.