Citations

ABSTRACT The ubiquitin‐proteasome system (UPS) is involved in the removal of damaged proteins and the activation of transcription factors, such as nuclear‐factor‐κB. Recent reports, however, questioned the functional activity of the UPS under conditions of increased oxidative stress, such as experimental hypercholesterolemia, which was the objective of our study. Pigs were placed on a normal chow diet (N) or on a hypercholesterolemic diet without (HC) or with vitamin C and E supplementation (HC+VIT) for 12 weeks. Compared with N, plasma concentration of total cholesterol increased in both HC and HC+VIT [76 ± 21 vs. 400 ± 148 ( P <0.05) and 329 ± 102 ( P <0.05) mg/dL], whereas increase in lipid peroxidation, as assessed by LDL‐malondialdehyde plasma concentration, was found in HC but not in HC+VIT [6.6 ± 0.7 vs. 8.5 ± 0.3 ( P <0.05) and 6.8 ± 0.7 nmol/mg protein]. In comparison with N, the level of ubiquitin conjugates in the coronary artery, as assessed by immunoblotting, increased by 42% in HC but not in HC+VIT and was localized predominantly to media vascular smooth muscle cells by immunostaining. There was no difference in proteasome proteolytic activity among the study groups. These results demonstrate that the UPS is functionally active in early atherogenesis despite increase in oxidative stress with important repercussions in the pathophysiology and therapy of cardiovascular diseases.

AbstractLittle effort has been made to quantitate adverse outcomes of monoclonal gammopathy of undetermined significance (MGUS) of the immunoglobulin M (IgM) class, which progresses to lymphoma or Waldenström macroglobulinemia, whereas IgA and IgG MGUS progress to multiple myeloma, primary amyloidosis (AL), or a related plasma cell disorder. From 1960 to 1994, IgM MGUS was diagnosed in 213 patients in southeastern Minnesota. The end point was progression to lymphoma or a related disorder, as assessed with the Kaplan-Meier method. The 213 patients were followed up for 1567 person-years (median, 6.3 years per patient). Lymphoma developed in 17 patients (relative risk [RR], 14.8), Waldenström macroglobulinemia in 6 (RR, 262), primary amyloidosis in 3 (RR, 16.3), and chronic lymphocytic leukemia in 3 (RR, 5.7). The relative risk of progression was 16-fold higher in the patients with IgM MGUS than in the white population of the Iowa Surveillance, Epidemiology, and End Results Program. Cumulative incidence of progression was 10% at 5 years, 18% at 10 years, and 24% at 15 years. On multivariate analysis, the serum monoclonal protein and serum albumin concentrations at diagnosis were the only risk factors for progression to lymphoma or a related disorder. Risk for progression to lymphoma or a related disorder at 10 years after the diagnosis of MGUS was 14% with an initial monoclonal protein concentration of 0.5 g/dL or less, 26% with 1.5 g/dL, 34% for 2.0 g/dL, and 41% for more than 2.5 g/dL. (Blood. 2003;102:3759-3764)

The Ca2+ mobilizing peptide, bradykinin (BK), stimulates endothelial nitric oxide synthase (eNOS)-derived cellular nitric oxide (NO)production in association with altering the subcellular distribution of the enzyme. In the present study we examine the influence of cellular GTPases,particularly the large GTPase dynamin, on BK-mediated eNOS localization and cellular NO production. BK stimulation of ECV cells, which were stably transfected with eNOS-GFP (eNOS-GFP ECV304), increased NO production. This was associated with the mobilization of eNOS-GFP protein into Triton X-100-insoluble fractions of cell lysates, and an internalization of plasmalemmal eNOS-GFP in live and fixed ECV 304 cells. Incubation of digitonin-permeabilized ECV304 cells with the non-hydrolyzed GTP analog,GTP-γ-S, abrogated the BK-mediated internalization of eNOS-GFP as assessed by confocal microscopy. Conversely, inhibition of clathrin-dependent endocytosis, via overexpression of AP 180 or pretreatment of cells with chlorpromazine, did not influence BK-mediated eNOS redistribution. Furthermore, specific inhibition of dynamin-2 GTPase function by overexpression of a dominant negative construct, K44A, prevented the BK-mediated enrichment of eNOS-GFP within low buoyant density,caveolin-enriched fractions of eNOS-GFP ECV304 cell lysates. Dynamin-2 K44A overexpression also markedly impaired BK-dependent, L-NAME-inhibited NO production as did incubation of permeabilized cells with GTP-γ-s. These studies demonstrate that disruption of dynamin- and GTP-dependent, but clathrin-independent, vesicle trafficking pathways impairs BK-dependent cellular NO production, via inhibition of the internalization of eNOS-containing plasmalemmal vesicles.

Background and Purpose— Mortality after cerebral infarction (CI) has remained unchanged during the past 20 years, despite advances in neurologic care. Key factors affecting survival may be underrecognized. The purpose of this study was to determine the rate and cause of mortality after first CI. Methods— In this case-control, population-based study, all available medical records were reviewed for Rochester (Minnesota) residents with a first CI between 1985 and 1989 to identify morbidities and cause of death. Predictors for mortality were analyzed. Results— First CI was recorded for 444 patients. Survival was 83% at 1 month, 71% at 1 year, and 46% at 5 years. The most frequent causes of death were cardiovascular events (22%), respiratory infection (21%), and initial stroke complications (14%). Recurrent stroke and cancer accounted for 9% and 7.5% of deaths, respectively. In the first month after CI, 51% of deaths were attributed to the initial CI, 22% to respiratory infections, and 12% to cardiovascular events. During the first year, 26% of deaths resulted from respiratory infections and 28% from cardiovascular disease. Mortality was higher among patients than controls for at least 2 years after CI. Age, cardiac comorbid conditions, CI severity, stroke recurrence, seizures, and respiratory and cardiovascular morbidities were independent predictors of death. Conclusions— In the first month after CI, mortality resulted predominantly from neurologic complications. Later mortality remained high because of respiratory and cardiovascular causes. To improve long-term survival after CI, aggressive management of pulmonary and cardiac disease is as important as secondary stroke prevention.

Background— Recent studies in animals suggest that circulating recipient endothelial precursors may participate in the biology of transplant vasculopathy. It is currently unknown whether a similar interaction between recipient endothelial cells and the vessel wall occurs in human subjects undergoing allogeneic cardiac transplantation. Methods and Results— Circulating endothelial cells and endothelial progenitor cells (EPCs) were quantified in 15 cardiac transplantation subjects with and without angiographic evidence of vasculopathy. In a separate series of experiments, the origin (donor or recipient) of transplant plaque endothelial cells was assessed in subjects who had undergone a gender-mismatched cardiac transplantation and had histological evidence of severe vasculopathy at the time of heart explantation. Circulating EPC outgrowth colonies in peripheral blood were significantly reduced in subjects with transplant vasculopathy compared with those without angiographic evidence of disease (EPC colony-forming units [CFU EPC ]: 4.5±1.9 versus 15.1±3.7, P <0.05). There was no significant difference in circulating endothelial cell numbers as defined by day 4 culture acetylated LDL/lectin assay in either of these patient groups. In a separate group of 5 subjects who underwent gender-mismatched cardiac transplantation, there was a significant seeding of recipient endothelial cells (range: 1% to 24% of all luminal endothelial cells) in large-vessel lumen and adventitial microvessel lumen of arteriopathic vessels. No opposite-sex chimeric cells were observed in control gender-matched transplantation scenarios. Conclusions— These data suggest that the human cardiac transplant arteriopathy is associated with reduction in circulating endothelial precursors and with seeding of recipient-derived endothelial cells at the site of plaque development.

Purpose: To assess the neurocognitive effects of cranial radiotherapy on patients with low-grade gliomas, we analyzed cognitive performance data collected in a prospective, intergroup clinical trial. Methods: Patients included 203 adults with supratentorial low-grade gliomas randomly assigned to a lower dose (50.4 Gy in 28 fractions) or a higher dose (64.8 Gy in 36 fractions) of localized radiotherapy. Folstein Mini-Mental State Examination (MMSE) scores and neurologic function scores (NFS) at baseline and key evaluations were analyzed. Median follow-up was 7.4 years in 101 patients still alive. A change of more than three MMSE points was considered clinically significant. Results: In patients without tumor progression, significant deterioration from baseline occurred at years 1, 2, and 5 in 8.2%, 4.6%, and 5.3% of patients, respectively. Most patients with an abnormal baseline MMSE score (< 27) experienced significant increases. Baseline variables such as radiation dose, conformal versus conventional radiotherapy, number of radiation fields, age, sex, tumor size, NFS, seizures, and seizure medications did not predict cognitive function changes. Conclusion: In this population, most low-grade glioma patients maintained a stable neurocognitive status after focal radiotherapy as measured by the MMSE. Patients with an abnormal baseline MMSE were more likely to have an improvement in cognitive abilities than deterioration after receiving radiotherapy. Only a small percentage of patients had cognitive deterioration after radiotherapy. However, more discriminating neurocognitive assessment tools may identify cognitive decline not apparent with the use of the MMSE.