Citations

Mutations in human ether-a-go-go-related gene 1 ( hERG) are linked to long QT syndrome type 2 (LQT2). hERG encodes the pore-forming α-subunits that coassemble to form rapidly activating delayed rectifier K+ current in the heart. LQT2-linked missense mutations have been extensively studied in noncardiac heterologous expression systems, where biogenic (protein trafficking) and biophysical (gating and permeation) abnormalities have been postulated to underlie the loss-of-function phenotype associated with LQT2 channels. Little is known about the properties of LQT2-linked hERG channel proteins in native cardiomyocyte systems. In this study, we expressed wild-type (WT) hERG and three LQT2-linked mutations in neonatal mouse cardiomyocytes and studied their electrophysiological and biochemical properties. Compared with WT hERG channels, the LQT2 missense mutations G601S and N470D hERG exhibited altered protein trafficking and underwent pharmacological correction, and N470D hERG channels gated at more negative voltages. The ΔY475 hERG deletion mutation trafficked similar to WT hERG channels, gated at more negative voltages, and had rapid deactivation kinetics, and these properties were confirmed in both neonatal mouse cardiomyocyte and human embryonic kidney (HEK)-293 cell expression systems. Differences between the cardiomyocytes and HEK-293 cell expression systems were that hERG current densities were reduced 10-fold and deactivation kinetics were accelerated 1.5- to 2-fold in neonatal mouse cardiomyocytes. An important finding of this work is that pharmacological correction of trafficking-deficient LQT2 mutations, as a potential innovative approach to therapy, is possible in native cardiac tissue.

The allocation of surgeries to operating rooms (ORs) is a challenging combinatorial optimization problem. There is also significant uncertainty in the duration of surgical procedures, which further complicates assignment decisions. In this paper, we present stochastic optimization models for the assignment of surgeries to ORs on a given day of surgery. The objective includes a fixed cost of opening ORs and a variable cost of overtime relative to a fixed length-of-day. We describe two types of models. The first is a two-stage stochastic linear program with binary decisions in the first stage and simple recourse in the second stage. The second is its robust counterpart, in which the objective is to minimize the maximum cost associated with an uncertainty set for surgery durations. We describe the mathematical models, bounds on the optimal solution, and solution methodologies, including an easy-to-implement heuristic. Numerical experiments based on real data from a large health-care provider are used to contrast the results for the two models and illustrate the potential for impact in practice. Based on our numerical experimentation, we find that a fast and easy-to-implement heuristic works fairly well, on average, across many instances. We also find that the robust method performs approximately as well as the heuristic, is much faster than solving the stochastic recourse model, and has the benefit of limiting the worst-case outcome of the recourse problem.

Clostridium septicumaortitis is a rare infection that is highly associated with underlying malignancy. We present a case of an 82-year-old male diagnosed with bothC. septicumaortitis and a high-grade cecal tubulovillous adenoma. The patient was offered aortic resection; however, he opted for only suppressive antibiotic therapy and a right hemicolectomy with ileocolonic anastomosis. He ultimately passed away 75 days following admission. The authors report on the connection betweenC. septicumaortitis and malignancy. The authors also discuss the need for prompt treatment with antibiotics once the infection is identified and the consideration of aortic resection given the risk of aneurysmal change with aortic dissection or rupture.

Purpose To assess the impact of age on outcome and to analyze the projected years of life lost in patients with multiple myeloma. Patients and Methods Ten thousand five hundred forty-nine patients were evaluated; 6,996 patients were treated with conventional chemotherapy, and 3,553 patients were treated with high-dose therapy with autologous stem-cell transplantation. Results Mean observed and relative overall survival times in the entire cohort were 3.7 and 3.9 years, respectively. Observed survival decreased steadily from 6.4 years in patients younger than age 50 years to 2.5 years in patients ≥ age 80 years. A similar decrease was noted for relative survival. Higher age correlated significantly with higher International Staging System (ISS) stage. Relative excess risk of death differed significantly between 10-year age cohorts beginning from age 40 years (P < .001 for age 50 to 59 v age 40 to 49, P < .001 for age 60 to 69 v age 50 to 59, P < .001 for age 70 to 79 v age 60 to 69, and P = .009 for age ≥ 80 v 70 to 79). The average years of life lost per patient was 16.8 years in the entire patient cohort and decreased steadily from 36.1 years in patients younger than 40 years old to 4.6 years in patients ≥ age 80 years. Conclusion Age is associated with higher ISS stage and is an important risk factor for early mortality. Survival declined continuously by each decade from age 50 to age ≥ 80 from more than 6 to less than 3 years. The average of years of life lost in patients with myeloma is higher than in many other cancers and amounts to more than 30 years in patients younger than 40 years old but decreases to less than 5 years in patients age 80 years or older.

Background— In giant cell arteritis (GCA), vasculitic damage of the aorta and its branches is combined with a syndrome of intense systemic inflammation. Therapeutically, glucocorticoids remain the gold standard because they promptly and effectively suppress acute manifestations; however, they fail to eradicate vessel wall infiltrates. The effects of glucocorticoids on the systemic and vascular components of GCA are not understood. Methods and Results— The immunoprofile of untreated and glucocorticoid-treated GCA was examined in peripheral blood and temporal artery biopsies with protein quantification assays, flow cytometry, quantitative real-time polymerase chain reaction, and immunohistochemistry. Plasma interferon-γ and interleukin (IL)-17 and frequencies of interferon-γ-producing and IL-17-producing T cells were markedly elevated before therapy. Glucocorticoid treatment suppressed the Th17 but not the Th1 arm in the blood and the vascular lesions. Analysis of monocytes/macrophages in the circulation and in temporal arteries revealed glucocorticoid-mediated suppression of Th17-promoting cytokines (IL-1β, IL-6, and IL-23) but sparing of Th1-promoting cytokines (IL-12). In human artery-severe combined immunodeficiency mouse chimeras, in which patient-derived T cells cause inflammation of engrafted human temporal arteries, glucocorticoids were similarly selective in inhibiting Th17 cells and leaving Th1 cells unaffected. Conclusions— Two pathogenic pathways mediated by Th17 and Th1 cells contribute to the systemic and vascular manifestations of GCA. IL-17-producing Th17 cells are sensitive to glucocorticoid-mediated suppression, but interferon-γ-producing Th1 responses persist in treated patients. Targeting steroid-resistant Th1 responses will be necessary to resolve chronic smoldering vasculitis. Monitoring Th17 and Th1 frequencies can aid in assessing disease activity in GCA.

Vps4 is a key enzyme that functions in endosomal protein trafficking, cytokinesis, and retroviral budding. Vps4 activity is regulated by its recruitment from the cytoplasm to ESCRT-III, where the protein oligomerizes into an active ATPase. The recruitment and oligomerization steps are mediated by a complex network of at least 12 distinct interactions between Vps4, ESCRT-III, Ist1, Vta1, and Did2. The order of events leading to active, ESCRT-III–associated Vps4 is poorly understood. In this study we present a systematic in vivo analysis of the Vps4 interaction network. The data demonstrated a high degree of redundancy in the network. Although no single interaction was found to be essential for the localization or activity of Vps4, certain interactions proved more important than others. The most significant among these were the binding of Vps4 to Vta1 and to the ESCRT-III subunits Vps2 and Snf7. In our model we propose the formation of a recruitment complex in the cytoplasm that is composed of Did2-Ist1-Vps4, which upon binding to ESCRT-III recruits Vta1. Vta1 in turn is predicted to cause a rearrangement of the Vps4 interactions that initiates the assembly of the active Vps4 oligomer.

Abstract Therapy-related myelodysplastic syndromes (t-MDSs) and acute myeloid leukemia (t-AML) have a poor prognosis with conventional therapy. Encouraging results are reported after allogeneic transplantation. We analyzed outcomes in 868 persons with t-AML (n = 545) or t-MDS (n = 323) receiving allogeneic transplants from 1990 to 2004. A myeloablative regimen was used for conditioning in 77%. Treatment-related mortality (TRM) and relapse were 41% (95% confidence interval [CI], 38-44) and 27% (24-30) at 1 year and 48% (44-51) and 31% (28-34) at 5 years, respectively. Disease-free (DFS) and overall survival (OS) were 32% (95% CI, 29-36) and 37% (34-41) at 1 year and 21% (18-24) and 22% (19-26) at 5 years, respectively. In multivariate analysis, 4 risk factors had adverse impacts on DFS and OS: (1) age older than 35 years; (2) poor-risk cytogenetics; (3) t-AML not in remission or advanced t-MDS; and (4) donor other than an HLA-identical sibling or a partially or well-matched unrelated donor. Five-year survival for subjects with none, 1, 2, 3, or 4 of these risk factors was 50% (95% CI, 38-61), 26% (20-31), 21% (16-26), 10% (5-15), and 4% (0-16), respectively (P < .001). These data permit a more precise prediction of outcome and identify subjects most likely to benefit from allogeneic transplantation.

Abstract Context: A reduction in maximal mitochondrial ATP production rate (MAPR) and mitochondrial DNA (mtDNA) abundance occurs with age in association with muscle weakness and reduced endurance in elderly people. Branched chain amino acids (BCAA) have been extensively used to improve physical performance. Objective: The objective was to determine whether an 8-h infusion of BCAA enhances MAPR equally in healthy young and elderly adults. Methods: Using a crossover study design, we compared the effect BCAA vs. saline infusion in 12 young (23.0 ± 0.8 yr) and 12 elderly (70.7 ± 1.1 yr) participants matched for sex and body mass index. Skeletal muscle MAPR and mtDNA abundance were measured in muscle biopsy samples obtained before and at the end of the 8-h infusion. Results: In young participants, MAPR with the substrates glutamate plus malate (supplying electrons to complex I) and succinate plus rotenone (complex II) increased in response to BCAA infusion, relative to a decline in MAPR in response to the saline infusion. In contrast, MAPR was unaffected by BCAA infusion in the elderly participants. Moreover, mtDNA abundance was lower in the elderly compared with the young participants but was unaffected by the BCAA infusion. Insulin and C-peptide concentrations declined over time during the saline infusion, but these declines were prevented by the BCAA infusion. Conclusions: BCAA increased skeletal muscle MAPR in the young participants in comparison with saline, but this effect was not seen in the elderly participants indicating, that unlike in the young, BCAA does not increase muscle mitochondrial function in the elderly.