Institutional Cost of Unplanned 30-Day Readmission Following Open and Endovascular Surgery.

BACKGROUND: Vascular surgical patients have a high rate of readmission, and the cost of readmission for these patients has not been described. Herein, we characterize and compare institutional index hospitalization and 30-day readmission cost following open and endovascular vascular procedures. METHODS: The American College of Surgeons National Surgical Quality Improvement Program database was used to identify inpatient open and endovascular procedures at a single institution, from January 2011 through June 2012. Variable and fixed costs for index hospitalization and unplanned 30-day readmissions were obtained using SAP BusinessObjects. Patient characteristics and outcome variables were analyzed using Student t tests or Wilcoxon rank-sum nonparametric tests for continuous variables and Fisher exact tests for categorical variables. RESULTS: One thousand twenty-six inpatient procedures were included in the analysis. There were 605 (59%) open and 421 (41%) endovascular procedures with a 30-day unplanned readmission rate of 16.9% and 17.8%, respectively (P = .679). The mean index hospitalization costs for open and endovascular procedures were US$27 653 and US$23 999, respectively (P = .146). The mean costs for 30-day unplanned readmission for open and endovascular procedures were US$19 117 and US$17 887, respectively (P = .635). Among open procedures, the mean cost for patients not readmitted was US$28 321 compared to US$31 115 for those readmitted (P = .003). Among endovascular procedures, the mean cost for patients not readmitted was US$26 908 compared to US$32 262 for those readmitted (P = .028). CONCLUSION: The cost of index hospitalization and 30-day unplanned readmission are similar for open and endovascular procedures. Readmitted patients had a higher mean index hospitalization cost irrespective of open or endovascular procedure.

Human leukocyte antigen-DR13 and DR15 are associated with short-term lung transplant outcomes.

BACKGROUND: Lung transplantation outcomes are among the least favorable, with most recipients eventually developing bronchiolitis obliterans syndrome (BOS) and subsequent graft failure. The presence of human leukocyte antigen (HLA)-DR has been implicated in the pathogenesis of BOS and may play a role in these poor outcomes. METHODS: Lung transplant donor and recipient data were retrospectively gathered from the United Network for Organ Sharing database from January 2006 to June 2013. Donor and recipient characteristics, proportion of recipients treated for first year rejection, and 5-y rates of survival and freedom from BOS were determined according to HLA-DR1, -DR7, -DR13, and -DR15 status in both donor and recipient. Each HLA-DR allele was stratified by donor-recipient pair positivity status. RESULTS: A total of 7402 lung transplant recipients met the inclusion and exclusion criteria. There were significant but small differences in donor and recipient characteristics for each HLA-DR group. The recipients in the D(-)R(+) pairing for HLA-DR13 and those in the D(+)R(-) pairing for HLA-DR15 had significantly higher rates of receiving treatment for rejection within the first year after transplant (P = 0.024 and P = 0.001, respectively). There were no differences in 5-y survival or freedom from BOS for any of the four HLA-DR alleles studied. CONCLUSIONS: There are higher rates of patients treated for rejection within the first year who are either negative for the HLA-DR15 allele but received a donor-positive lung or positive for the HLA-DR13 allele but received a donor-negative lung for that allele. However, these differences do not appear to affect long-term outcomes.

Exploring autoimmunity in the pathogenesis of abdominal aortic aneurysms.

The abdominal aortic aneurysm (AAA) is a disease process that carries significant morbidity and mortality in the absence of early identification and treatment. While current management includes surveillance and surgical treatment of low- and high-risk aneurysms, respectively, our narrow understanding of the pathophysiology of AAAs limits our ability to more effectively manage and perhaps even prevent the occurrence of this highly morbid disease. Over the past couple of decades, there has been considerable interest in exploring the role of autoimmunity as an etiological component of AAA. This review covers the current literature pertaining to this immunological process, focusing on research that highlights the local and systemic immune components found in both human patients and murine models. A better understanding of the autoimmune mechanisms in the pathogenesis of AAAs can pave the way to novel and improved treatment strategies in this patient population.

The HMGB1-RAGE axis mediates traumatic brain injury-induced pulmonary dysfunction in lung transplantation.

Traumatic brain injury (TBI) results in systemic inflammatory responses that affect the lung. This is especially critical in the setting of lung transplantation, where more than half of donor allografts are obtained postmortem from individuals with TBI. The mechanism by which TBI causes pulmonary dysfunction remains unclear but may involve the interaction of high-mobility group box-1 (HMGB1) protein with the receptor for advanced glycation end products (RAGE). To investigate the role of HMGB1 and RAGE in TBI-induced lung dysfunction, RAGE-sufficient (wild-type) or RAGE-deficient (RAGE(-/-)) C57BL/6 mice were subjected to TBI through controlled cortical impact and studied for cardiopulmonary injury. Compared to control animals, TBI induced systemic hypoxia, acute lung injury, pulmonary neutrophilia, and decreased compliance (a measure of the lungs' ability to expand), all of which were attenuated in RAGE(-/-) mice. Neutralizing systemic HMGB1 induced by TBI reversed hypoxia and improved lung compliance. Compared to wild-type donors, lungs from RAGE(-/-) TBI donors did not develop acute lung injury after transplantation. In a study of clinical transplantation, elevated systemic HMGB1 in donors correlated with impaired systemic oxygenation of the donor lung before transplantation and predicted impaired oxygenation after transplantation. These data suggest that the HMGB1-RAGE axis plays a role in the mechanism by which TBI induces lung dysfunction and that targeting this pathway before transplant may improve recipient outcomes after lung transplantation.

Recipient body mass index and age interact to impact survival after heart transplantation.

Although recipient body mass index (BMI) and age are known risk factors for mortality after heart transplantation, how they interact to influence survival is unknown. Our study utilized the UNOS registry from 1997 to 2012 to define the interaction between BMI and age and its impact on survival after heart transplantation. Recipients were stratified by BMI: underweight (<18.5), normal weight (18.5-24.99), overweight (25-29.99), and either moderate (30-34.99), severe (35-39.99), or very severe (≥40) obesity. Recipients were secondarily stratified based on age: 18-40 (younger recipients), 40-65 (reference group), and ≥65 (advanced age recipients). Among younger recipients, being underweight was associated with improved adjusted survival (HR 0.902; p = 0.010) while higher mortality was seen in younger overweight recipients (HR 1.260; p = 0.005). However, no differences in adjusted survival were appreciated in underweight and overweight advanced age recipients. Obesity (BMI ≥ 30) was associated with increased adjusted mortality in normal age recipients (HR 1.152; p = 0.021) and even more so with young (HR 1.576; p < 0.001) and advanced age recipients (HR 1.292; p = 0.001). These results demonstrate that BMI and age interact to impact survival as age modifies BMI-mortality curves, particularly with younger and advanced age recipients.

Lung transplantation: chronic allograft dysfunction and establishing immune tolerance.

Despite significant medical advances since the advent of lung transplantation, improvements in long-term survival have been largely unrealized. Chronic lung allograft dysfunction, in particular obliterative bronchiolitis, is the primary limiting factor. The predominant etiology of obliterative bronchiolitis involves the recipient's innate and adaptive immune response to the transplanted allograft. Current therapeutic strategies have failed to provide a definitive treatment paradigm to improve long-term outcomes. Inducing immune tolerance is an emerging therapeutic strategy that abrogates allograft rejection, avoids immunosuppression, and improves long-term graft function. The aim of this review is to discuss the key immunologic components of obliterative bronchiolitis, describe the state of establishing immune tolerance in transplantation, and highlight those strategies being evaluated in lung transplantation.

Impact of donor age on survival after heart transplantation: an analysis of the United Network for Organ Sharing (UNOS) registry.

BACKGROUND: Data are limited regarding the influence of donor age on outcomes after heart transplantation. We sought to determine if advanced donor age is associated with differences in survival after heart transplantation and how this compares to waitlist survival. METHODS: All adult heart transplants from 2000 to 2012 were identified using the United Network for Organ Sharing database. Donors were stratified into four age groups: 18-39 (reference group), 40-49, 50-54, and 55 and above. Propensity scoring was used to compare status IA waitlist patients who did not undergo transplantation with IA recipients who received hearts from advanced age donors. The primary outcome of interest was recipient survival and this was analyzed with multivariate Cox regression analysis and the Kaplan-Meier method. RESULTS: A total of 22,960 adult heart transplant recipients were identified. Recipients of hearts from all three older donor groups had significantly increased risk of mortality (HR, 1.187-1.426, all p < 0.001) compared to recipients from donors age 18 to 39. Additionally, propensity-matched status IA patients managed medically without transplantation had significantly worse adjusted survival than status IA recipients who received hearts from older donors age ≥55 (HR, 1.362, p < 0.001). CONCLUSIONS: Compared to donors aged 18-39, age 40 and above is associated with worse adjusted recipient survival in heart transplantation. This survival difference becomes more pronounced as age increases to above 55. However, the survival rate among status IA patients who receive hearts from advanced age donors (≥55) is significantly better compared to similar status IA patients who are managed without transplantation.

Nuclear lamins in cell regulation and disease.

The nuclear lamins are type V intermediate filament proteins that form meshworks at the inner aspect of the nuclear envelope and are also present throughout the nuclear interior. Through these meshwork structures, lamins regulate the shape, size, and mechanical properties of the nucleus. During the last 25 years, the Goldman laboratory has studied the organization and dynamic properties of the lamins in the nucleus. These studies have characterized the role of lamin phosphorylation in nuclear lamina assembly and disassembly during mitosis. Furthermore, our studies have demonstrated a role for the lamins in chromatin modification and epigenetics, transcription, and DNA replication. Recently, the discovery of numerous mutations in the gene encoding A-type lamins causing the collection of diseases known as laminopathies has provided new insights into the roles of lamins in cellular regulation and differentiation.

The nuclear pore complex.

Nuclear pore complexes, the conduits for information exchange between the nucleus and cytoplasm, appear broadly similar in eukaryotes from yeast to human. Precisely how nuclear pore complexes regulate macromolecular and ionic traffic remains unknown, but recent advances in the identification and characterization of components of the complex by proteomics and genomics have provided new insights.

Germline and developmental roles of the nuclear transport factor importin alpha3 in C. elegans.

The importin alpha family of transport factors mediates the nuclear import of classical nuclear localization signal-containing proteins. In order to understand how multiple importin alpha proteins are regulated both in individual cells and in a whole organism, the three importin alpha (ima) genes of Caenorhabditis elegans have been identified and studied. All three IMAs are expressed in the germline; however, only IMA-3 is expressed in the soma. RNA interference (RNAi) experiments demonstrate that IMA-3 is required for the progression of meiotic prophase I during oocyte development. Loss of IMA-3 expression leads also to a disruption of the nuclear pore complex accompanied by the mis-localization of P granules. A range of defects occurring in ima-3(RNAi) F1 progeny further supports a role for IMA-3 during embryonic and larval development. The functional association of IMA-3 with distinct cellular events, its expression pattern and intracellular localization indicate that regulation of the nuclear transport machinery is involved in the control of developmental pathways.

Role of importin-beta in coupling Ran to downstream targets in microtubule assembly.

The guanosine triphosphatase Ran stimulates assembly of microtubule asters and spindles in mitotic Xenopus egg extracts. A carboxyl-terminal region of the nuclear-mitotic apparatus protein (NuMA), a nuclear protein required for organizing mitotic spindle poles, mimics Ran's ability to induce asters. This NuMA fragment also specifically interacted with the nuclear transport factor, importin-beta. We show that importin-beta is an inhibitor of microtubule aster assembly in Xenopus egg extracts and that Ran regulates the interaction between importin-beta and NuMA. Importin-beta therefore links NuMA to regulation by Ran. This suggests that similar mechanisms regulate nuclear import during interphase and spindle assembly during mitosis.

Antihypertensive effects of valsartan/hydrochlorothiazide combination in essential hypertension.

Fixed-dose combination therapy has received increased interest since publication of JNC-VI report and WHO/ISH guidelines 1999. We compared in a randomized, double-blind study the efficacy and tolerability of valsartan 80 mg combined with hydrochlorothiazide (HCTZ) 12.5 mg to monotherapy with either HCTZ 12.5 mg or 25 mg in patients with essential hypertension inadequately controlled by previous HCTZ 12.5 mg monotherapy. Two hundred and seventeen patients whose blood pressure (BP) control remained poor (95 mmHg < or = sitting diastolic BP < 115 mmHg) after a 4-week single-blind period with HCTZ 12.5 mg were randomized to receive either combination therapy with valsartan 80 mg plus HCTZ 12.5 mg (V/HCTZ) or monotherapy with HCTZ 12.5 mg or HCTZ 25 mg for 8 weeks. Reduction of sitting trough diastolic BP between baseline and week 8 as well as tolerability was evaluated. Reduction in trough diastolic BP was most pronounced in the V/HCTZ group (-11.3 mmHg) and significantly greater than in the HCTZ 12.5 mg group (-2.9 mmHg, p < 0.001) and the HCTZ 25 mg group (-5.7 mmHg, p < 0.001). Tolerability of study medication was comparable between all three groups. In conclusion, switching to V/HCTZ combination therapy provides an additional lowering of BP compared to dosage increase of the thiazide in patients with BP insufficiently controlled by HCTZ 12.5 mg monotherapy.

A novel shuttling protein, 4E-T, mediates the nuclear import of the mRNA 5' cap-binding protein, eIF4E.

The eukaryotic translation initiation factor 4E (eIF4E) plays an important role in the control of cell growth. eIF4E binds to the mRNA 5' cap structure m(7)GpppN (where N is any nucleotide), and promotes ribosome binding to the mRNA in the cytoplasm. However, a fraction of eIF4E localizes to the nucleus. Here we describe the cloning and functional characterization of a new eIF4E-binding protein, referred to as 4E-T (eIF4E-Transporter). We demonstrate that 4E-T is a nucleocytoplasmic shuttling protein that contains an eIF4E-binding site, one bipartite nuclear localization signal and two leucine-rich nuclear export signals. eIF4E forms a complex with the importin alphabeta heterodimer only in the presence of 4E-T. Overexpression of wild-type 4E-T, but not of a mutant defective for eIF4E binding, causes the nuclear accumulation of HA-eIF4E in cells treated with leptomycin B. Taken together, these results demonstrate that the novel nucleocytoplasmic shuttling protein 4E-T mediates the nuclear import of eIF4E via the importin alphabeta pathway by a piggy-back mechanism.

Transport pathways of macromolecules between the nucleus and the cytoplasm.

Transport between the nucleus and cytoplasm involves both stationary components and mobile factors acting in concert to move macromolecules through the nuclear pore complex. Multiple transport pathways requiring both unique and shared components have been identified. In the past 18 months, new findings have shed light on the nature of some of the mobile components of these pathways. New receptor-cargo pairs for both import and export pathways have been identified extending the breadth of known transport pathways. Surprising findings on the role of Ran and energy in transport have changed our way of thinking about the mechanism of movement through the nuclear pore.

Nuclear import of DNA in digitonin-permeabilized cells.

DNA can enter intact mammalian nuclei with varying degrees of efficiency in both transfected and microinjected cells, yet very little is known about the mechanism by which it crosses the nuclear membrane. Nucleocytoplasmic transport of fluorescently labeled DNA was studied using a digitonin-permeabilized cell system. DNA accumulated in the nucleus with a punctate staining pattern in over 80% of the permeabilized HeLa cells. Nuclear localization of the labeled DNA was energy dependent and occurred through the nuclear pore, but did not require the addition of soluble cytoplasmic protein factors necessary for protein import.

Association of the T-cell protein tyrosine phosphatase with nuclear import factor p97.

Alternative splicing of the T-cell protein tyrosine phosphatase (TCPTP) transcript generates two forms of the enzyme that differ at their extreme C termini: a 48-kDa endoplasmic reticulum-associated form and a 45-kDa nuclear form. By affinity chromatography, using GST-TCPTP fusion proteins, we have isolated three cytoplasmic proteins of 120, 116, and 97 kDa that interact with TCPTP. The p120 protein associated with residues 377-415 from the C terminus of the 48-kDa form of TCPTP, whereas the recognition site for p97 and p116 was mapped to residues 350-381 encompassing the TCPTP nuclear localization sequence (NLS). The TCPTP NLS was shown to be bipartite, requiring basic residues 350-358 (basic cluster I) and 377-381 (basic cluster II), the sites of interaction with p97 and p116, for efficient nuclear translocation. The interaction between p97, p116, and the TCPTP NLS appeared unique in that these proteins did not form a stable interaction with the classical NLS of SV40 large T antigen or the standard bipartite NLS of nucleoplasmin. Sequence analysis of p97 identified it as the nuclear import factor p97 (importin-beta), which is an essential component of the nuclear import machinery. In assays in vitro in permeabilized cells, p97 was necessary but not sufficient for optimal nuclear import of TCPTP. We found that TCPTP co-immunoprecipitated with the nuclear import factor p97 from cell lysates and that purified recombinant p97 and TCPTP interacted directly in vitro. These results indicate selectivity in the binding of p97 and p116 to the TCPTP NLS and suggest that p97 may mediate events that are distinct from the classical nuclear import process. Moreover, these results demonstrate that the C-terminal segment of TCPTP contains docking sites for interaction with proteins that may function to target the enzyme to defined intracellular locations and in the process regulate TCPTP function.

Functional domains in nuclear import factor p97 for binding the nuclear localization sequence receptor and the nuclear pore.

The interaction of the nuclear protein import factor p97 with the nuclear localization sequence (NLS) receptor, the nuclear pore complex, and Ran/TC4 is important for coordinating the events of protein import to the nucleus. We have mapped the binding domains on p97 for the NLS receptor and the nuclear pore. The NLS receptor-binding domain of p97 maps to the C-terminal 60% of the protein between residues 356 and 876. The pore complex-binding domain of p97 maps to residues 152-352. The pore complex-binding domain overlaps the Ran-GTP- and Ran-GDP-binding domains on p97, but only Ran-GTP competes for docking in permeabilized cells. The N-ethylmaleimide sensitivity of the p97 for docking was investigated and found to be due to inhibition of p97 binding to the pore complex and to the NLS receptor. Site-directed mutagenesis of conserved cysteine residues in the pore- and receptor-binding domains identified two cysteines, C223 and C228, that were required for p97 to bind the nuclear pore. Inhibition studies on docking and accumulation of a NLS protein provided additional evidence that the domains identified biochemically are the functional domains involved in protein import. Together, these results suggest that Ran-GTP dissociates the receptor complex and prevents p97 binding to the pore by inducing a conformational change in the structure of p97 rather than simple competition for binding sites.

Nucleolar protein B23 stimulates nuclear import of the HIV-1 Rev protein and NLS-conjugated albumin.

Nucleolar phosphoprotein B23 is a putative ribosome assembly factor with a relatively high affinity for peptides containing sequences of nuclear localization signals (NLSs) of the SV40 T-antigen type [Szebeni, A., Herrera, J. E., & Olson, O. J. (1995) Biochemistry 34, 8037-8042]. The effects of protein B23 on nuclear import were determined by an in vitro assay [Dean, D. A., & Kasamatsu, H. (1994) J. Biol. Chem. 269, 4910-4916] using NLS peptide-conjugated bovine serum albumin (NLS-BSA) or the HIV-1 Rev protein as substrates for import into isolated rat liver nuclei. The import was ATP-dependent and inhibited by wheat germ agglutinin or by an antibody against p97, a component of the nuclear import system. The rate of import of either substrate was increased if protein B23 was added to the incubation medium. Similar enhancements of import were seen with both isoforms (B23.1 and B23.2). The stimulatory effect on Rev protein import was saturable with maximum stimulation (2-3-fold) at a molar ratio of protein B23:Rev of approximately 1:1. Phosphorylation of protein B23.1 by casein kinase II produced an additional doubling of the import rate. This effect was not seen if protein B23.1 was phosphorylated with a cdc2 type protein kinase. Mutant forms of protein B23.1 in which the nuclear localization signal was either deleted or altered did not stimulate import of the substrates. These results suggest that protein B23 plays a role as an accessory factor in the nuclear import of the NLS-containing proteins and that phosphorylation at sites in the highly acidic segments of the protein enhances the stimulatory effect.

Different binding domains for Ran-GTP and Ran-GDP/RanBP1 on nuclear import factor p97.

Several proteins are required for the transport of nuclear proteins from the cytoplasm to the nucleus, including the nuclear location sequence receptor (NLS receptor), p97, the small nuclear GTPase Ran/TC4, and several nucleoporins. The interaction of Ran with p97 is thought to regulate the interaction of these transport components. Ran-GTP alone binds p97, but Ran-GDP binds p97 only in conjunction with RanBP1. Using site-directed mutagenesis and deletion analysis, we have identified two distinct but overlapping binding domains for Ran-GTP and Ran-GDP/RanBP1 on p97. A short acidic sequence in p97 is part of the Ran-GDP/RanBP1 binding domain, possibly functioning in a similar manner as the C-terminal acidic sequence in Ran. A conserved cysteine residue in p97, Cys-158, is required for binding Ran-GDP/RanBP1, but not for binding of Ran-GTP to p97. In a permeabilized cell protein import assay, a mutant p97 with alanine substituted for Cys-158 is unable to support import in the presence of NLS receptor and Ran. These results support a direct active role for Ran-GDP in the receptor complex and provide evidence that the activity of downstream effectors of small GTPases may be regulated by both GTP- and GDP-bound forms of the protein.

Nuclear import of U snRNPs requires importin beta.

Macromolecules that are imported into the nucleus can be divided into classes according to their nuclear import signals. The best characterized class consists of proteins which carry a basic nuclear localization signal (NLS), whose transport requires the importin alpha/beta heterodimer. U snRNP import depends on both the trimethylguanosine cap of the snRNA and a signal formed when the Sm core proteins bind the RNA. Here, factor requirements for U snRNP nuclear import are studied using an in vitro system. Depletion of importin alpha, the importin subunit that binds the NLS, is found to stimulate rather than inhibit U snRNP import. This stimulation is shown to be due to a common requirement for importin beta in both U snRNP and NLS protein import. Saturation of importin beta-mediated transport with the importin beta-binding domain of importin alpha blocks U snRNP import both in vitro and in vivo. Immunodepletion of importin beta inhibits both NLS-mediated and U snRNP import. While the former requires re-addition of both importin alpha and importin beta, re-addition of importin beta alone to immunodepleted extracts was sufficient to restore efficient U snRNP import. Thus importin beta is required for U snRNP import, and it functions in this process without the NLS-specific importin alpha.