OBJECTIVEAssays for serum total glycated proteins (fructosamine) and the more specific glycated albumin may be useful indicators of hyperglycemia in dialysis patients, either as substitutes or adjuncts to standard markers such as hemoglobin A1c, as they are not affected by erythrocyte turnover. However, their relationship with long-term outcomes in dialysis patients is not well described.RESEARCH DESIGN AND METHODSWe measured fructosamine and glycated albumin in baseline samples from 503 incident hemodialysis participants of a national prospective cohort study, with enrollment from 1995–1998 and median follow-up of 3.5 years. Outcomes were all-cause and cardiovascular disease (CVD) mortality and morbidity (first CVD event and first sepsis hospitalization) analyzed using Cox regression adjusted for demographic and clinical characteristics, and comorbidities.RESULTSMean age was 58 years, 64% were white, 54% were male, and 57% had diabetes. There were 354 deaths (159 from CVD), 302 CVD events, and 118 sepsis hospitalizations over follow-up. Both fructosamine and glycated albumin were associated with all-cause mortality; adjusted HR per doubling of the biomarker was 1.96 (95% CI 1.38–2.79) for fructosamine and 1.40 (1.09–1.80) for glycated albumin. Both markers were also associated with CVD mortality [fructosamine 2.13 (1.28–3.54); glycated albumin 1.55 (1.09–2.21)]. Higher values of both markers were associated with trends toward a higher risk of hospitalization with sepsis [fructosamine 1.75 (1.01–3.02); glycated albumin 1.39 (0.94–2.06)].CONCLUSIONSSerum fructosamine and glycated albumin are risk factors for mortality and morbidity in hemodialysis patients.
PurposeTo establish conditionally immortal mouse corneal endothelial cell lines with genetically matched Slc4a11+/+ and Slc4a11−/− mice as a model for investigating pathology and therapies for SLC4A11 associated congenital hereditary endothelial dystrophy (CHED) and Fuchs' endothelial corneal dystrophy.MethodsWe intercrossed H-2Kb-tsA58 mice (Immortomouse) expressing an IFN-γ dependent and temperature-sensitive mutant of the SV40 large T antigen (tsTAg) with Slc4a11+/+ and Slc4a11−/− C57BL/6 mice. The growth characteristics of the cell lines was assessed by doubling time. Ion transport activities (Na+/H+ exchange, bicarbonate, lactate, and Slc4a11 ammonia transport) were analyzed by intracellular pH measurement. The metabolic status of the cell lines was assessed by analyzing TCA cycle intermediates via gas chromatography mass spectrometry (GC-MS).ResultsThe immortalized Slc4a11+/+ and Slc4a11−/− mouse corneal endothelial cells (MCECs) remained proliferative through passage 49 and maintained similar active ion transport activity. As expected, proliferation was temperature sensitive and IFN-γ dependent. Slc4a11−/− MCECs exhibited decreased proliferative capacity, reduced NH3:H+ transport, altered expression of glutaminolysis enzymes similar to the Slc4a11−/− mouse, and reduced proportion of TCA cycle intermediates derived from glutamine with compensatory increases in glucose flux compared with Slc4a11+/+ MCECs.ConclusionsThis is the first report of the immortalization of MCECs. Ion transport of the immortalized endothelial cells remains active, except for NH3:H+ transporter activity in Slc4a11−/− MCECs. Furthermore, Slc4a11−/− MCECs recapitulate the glutaminolysis defects observed in Slc4a11−/− mouse corneal endothelium, providing an excellent tool to study the pathogenesis of SLC4A11 mutations associated with corneal endothelial dystrophies and to screen potential therapeutic agents.
The conventional Slc4a11 knockout (KO) shows significant corneal edema at eye opening, a fact that complicates the study of the initial events leading to edema. An inducible KO would provide opportunities to examine early events following loss of Slc4a11 activity.
METHODS.Slc4a11 Flox (SF) mice were crossed with mice expressing the estrogen receptor Cre Recombinase fusion protein and fed tamoxifen (Tm) for two weeks. Corneal thickness (CT) was measured by OCT. At eight weeks endpoint, oxidative damage, tight junction integrity, stromal lactate concentration, endothelial permeability, differentially expressed transporters, and junction proteins were determined. Separately, a keratocyte only inducible Slc4a11 KO was also examined.
RESULTS.At four weeks post-Tm induction Slc4a11 transcript levels were 2% of control. Corneal thickness increased gradually and was 50% greater than Wild Type (WT) after eight weeks with significantly altered endothelial morphology, increased nitrotyrosine staining, significantly higher stromal lactate, decreased expression of lactate transporters and Na-K ATPase activity, higher ATP, altered expression of tight and adherens junctions, and increased fluorescein permeability. No significant differences in CT were found between WT and keratocyte only Slc4a11 KO.
CONCLUSIONS.The Slc4a11 inducible KO shows development of a similar phenotype as the conventional KO, thereby validating the model and providing a tool for further use in examining the sequence of cellular events by use of noninvasive in vivo physiological probes.
These results support the hypothesis that preconditioning by hypoxia or exposure to FG-4592 improves corneal endothelial cell survival and may also provide protection during surgical trauma.
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