Ravi K. Veeraswamy

GSTP1 CpG Island Hypermethylation Is Responsible for the Absence of GSTP1 Expression in Human Prostate Cancer Cells

GSTP1 CpG island hypermethylation is the most common somatic genome alteration described for human prostate cancer (PCA); lack of GSTP1 expression is characteristic of human PCA cells in vivo. We report here that loss of GSTP1 function may have been selected during the pathogenesis of human PCA. Using a variety of techniques to detect GSTP1 CpG island DNA hypermethylation in PCA DNA, we found only hypermethylated GSTP1 alleles in each PCA cell in all but two PCA cases studied. In these two cases, CpG island hypermethylation was present at only one of two GSTP1 alleles in PCA DNA. In one of the cases, DNA hypermethylation at one GSTP1 allele and deletion of the other GSTP1 allele were evident. In the other case, an unmethylated GSTP1 allele was detected, accompanied by abundant GSTP1 expression. GSTP1 CpG island DNA hypermethylation was responsible for lack of GSTP1 expression by LNCaP PCA cells: treatment of the cells with 5-azacytidine (5-aza-C), an inhibitor of DNA methyltransferases, reversed the GSTP1 promoter DNA hypermethylation, activated GSTP1 transcription, and restored GSTP1 expression. GSTP1 promoter activity, assessed via transfection of GSTP1 promoter-CAT reporter constructs in LNCaP cells, was inhibited by SssI-catalyzed CpG dinucleotide methylation. Remarkably, although selection for loss of GSTP1 function may be inferred for human PCA, GSTP1 did not act like a tumor suppressor gene, as LNCaP cells expressing GSTP1, either after 5-aza-C treatment or as a consequence of transfection with GSTP1 cDNA, grew well in vitro and in vivo. Perhaps, GSTP1 inactivation may render prostatic cells susceptible to additional genome alterations, caused by electrophilic or oxidant carcinogens, that provide a selective growth advantage.

Interferon-producing Cells Fail to Induce Proliferation of Naive T Cells but Can Promote Expansion and T Helper 1 Differentiation of Antigen-experienced Unpolarized T Cells

Interferon-producing cells (IPCs) secrete high levels of type I interferon in response to certain viruses. The lack of lineage markers, the expression of major histocompatibility complex (MHC) class II and the capacity to stimulate allogeneic T cells have led these cells to be classified as a subset of dendritic cells (DCs), called plasmacytoid DCs (PDCs). However, the role of IPCs/PDCs in initiating primary immune responses remains elusive. Here we examined the antigen presenting capacity of murine IPCs in antigen specific systems. While CD8α+ and CD11b+ DCs induced logarithmic expansion of naive CD4 and CD8 T cells, without conferring T helper commitment at a first encounter, primary IPCs lacked the ability to stimulate naive T cells. However, when antigen-experienced, nonpolarized T cells expanded by classical DC subsets, were restimulated by IPCs, they proliferated and produced high amounts of IFN-γ. These data indicate that IPCs can effectively stimulate preactivated or memory-type T cells and exert an immune-regulatory role. They also suggest that expansion of naive T cells and acquisition of effector function during antigen-specific T cell responses may involve different antigen-presenting cell (APC) types. Independent and coordinated control of T cell proliferation and differentiation would provide the immune system with greater flexibility in regulating immune responses.

Frailty increases the risk of 30-day mortality, morbidity, and failure to rescue after elective abdominal aortic aneurysm repair independent of age and comorbidities

BACKGROUND Frailty, defined as a biologic syndrome of decreased reserve and resistance to stressors, has been linked to adverse outcomes after surgery. We evaluated the effect of frailty on 30-day mortality, morbidity, and failure to rescue (FTR) in patients undergoing elective abdominal aortic aneurysm (AAA) repair. METHODS Patients undergoing elective endovascular AAA repair (EVAR) or open AAA repair (OAR) were identified in the National Surgical Quality Improvement Program database for the years 2005 to 2012. Frailty was assessed using the modified frailty index (mFI) derived from the Canadian Study of Health and Aging (CSHA). The primary outcome was 30-day mortality, and secondary outcomes included 30-day morbidity and FTR. The effect of frailty on outcomes was assessed by multivariate regression analysis, adjusted for age, American Society of Anesthesiology (ASA) class, and significant comorbidities. RESULTS Of 23,207 patients, 339 (1.5% overall; 1.0% EVAR and 3.0% OAR) died ≤30 days of repair. One or more complications occurred in 2567 patients (11.2% overall; 7.8% EVAR and 22.1% OAR). Odds ratios (ORs) for mortality adjusted for age, ASA class, and other comorbidities in the group with the highest frailty score were 1.9 (95% confidence interval [CI], 1.2-3.0) after EVAR and 2.3 (95% CI, 1.4-3.7) after OAR. Similarly, compared with the least frail, the most frail patients were significantly more likely to experience severe (Clavien-Dindo class IV) complications after EVAR (OR, 1.7; 95% CI, 1.3-2.1) and OAR (OR, 1.8; 95%, CI, 1.5-2.1). There was also a higher FTR rate among frail patients, with 1.7-fold higher risk odds of mortality (95% CI, 1.2-2.5) in the highest tertile of frailty compared with the lowest when postoperative complications occurred. CONCLUSIONS Higher mFI, independent of other risk factors, is associated with higher mortality and morbidity in patients undergoing elective EVAR and OAR. The mortality in frail patients is further driven by FTR from postoperative complications. Preoperative recognition of frailty may serve as a useful adjunct for risk assessment.

Dendritic Cells Process and Present Antigens Across A Range of Maturation States

We isolated dendritic cells (DC) from lymphoid organs of mice bearing a transgene for a membrane-bound form of the model protein hen egg white lysozyme (HEL). DC from the spleen had a lower representation of costimulatory molecules and class II MHC molecules than those isolated from lymph nodes and thymi. Splenic DC were capable of further maturation by in vivo treatment of mice with LPS. The immature DC from spleen processed HEL and displayed the chemically dominant epitope as evidenced by FACS analysis. These immature DC also presented this epitope to CD4+ T cells. Splenic DC from another transgenic mouse (ML-5) containing serum HEL also showed the ability to process and present Ag despite low levels of circulating HEL. In vitro-derived DC from the bone marrow (bone marrow-derived DC) of mHEL mice also displayed immature to mature features and in both cases displayed HEL peptides as well as SDS-stable MHC class II molecules. Immature bone marrow-derived DC also processed exogenous HEL. We conclude that the DC sets normally found in tissue show a scale of maturation features but even the most immature process and present peptides by MHC class II molecules.

Left subclavian artery coverage during thoracic endovascular aortic repair and risk of perioperative stroke or death

INTRODUCTION Left subclavian artery (LSA) coverage during thoracic endovascular aortic repair (TEVAR) is often necessary due to anatomic factors and is performed in to up to 40% of procedures. Despite the frequency of LSA coverage during TEVAR, reported associations with risk of periprocedural stroke or death are inconsistent in reported literature. We examined the 2005-2008 American College of Surgeons National Surgical Quality Improvement Program Participant Use Data file to determine associations between LSA coverage during TEVAR and risk of perioperative stroke or death. METHODS Current procedural terminology (CPT) codes were used to identify patients undergoing TEVAR, LSA coverage, and subclavian revascularization. Patients undergoing coronary bypass, ascending aortic repair, abdominal aortic aneurysm repair, or nonvascular intra-abdominal procedures during the same operation were excluded. Perioperative stroke and mortality associations with LSA coverage were examined using logistic regression models for each outcome. Significance was assessed at α = 0.05, with univariable P < .05 required for multivariable model entry. RESULTS Eight hundred forty-five TEVAR procedures were identified, of which 52 patients were excluded due to additional major procedures performed with TEVAR. Seven hundred thirty-three of the remaining 793 procedures included CPT codes indicating primary placement of an initial thoracic endograft and form the basis of this analysis. LSA coverage occurred in 279 procedures (38%). Thirty-day stroke and mortality rates were 5.7% and 7.0%, respectively. LSA coverage was associated with increased 30-day risk of stroke in multivariable modeling (odds ratio [OR], 2.17 95% confidence interval [CI], 1.13-4.14; P = .019). Other significant multivariable risk factors for stroke included proximal aortic cuff placement during TEVAR (OR, 2.58; 95% CI, 1.30-5.16; P = .007) and emergency procedure status (OR, 3.60; 95% CI, 1.87-6.94; P < .001). No significant association between LSA coverage and perioperative mortality was identified (univariable OR, 1.70; 95% CI, 0.98-2.93; P = .0578). CONCLUSION LSA coverage during thoracic endovascular repair is associated with increased risk of perioperative stroke following TEVAR. Further evidence is needed to determine whether procedural modifications, including LSA revascularization, reduce the incidence of stroke associated with TEVAR.

Endovascular Repair for Diverse Pathologies of the Thoracic Aorta: An Initial Decade of Experience

BACKGROUND Endovascular grafts have rapidly evolved as a minimally invasive treatment for a variety of acute and chronic disorders of the thoracic aorta. Application of this technology at a single center is reported. STUDY DESIGN Between 1998 and 2007, 197 patients underwent thoracic endovascular aortic repair. Primary indications included degenerative aneurysms (n = 121), type B aortic dissection (n = 44), mycotic aneurysms (n = 9), traumatic disruptions (n = 9), intramural hematoma (n = 5), pseudoaneurysm (n = 4), and miscellaneous pathology (n = 5). An analysis of patient demographics, periprocedural records, complications, reinterventions, and survival was conducted. RESULTS Thirty-day mortality was 6%, which was lowest among patients undergoing treatment for a degenerative thoracic aortic aneurysm (2.4%, 3 of 121). Major adverse events included stroke in 3%, spinal cord ischemia in 2%, peripheral vascular repair in 4.5%, renal failure in 4.5%, and open conversion in one patient (0.5%). Both preoperative serum creatinine (odds ratio 1.44, 95% CI 1.02 to 2.04, p = 0.039) and number of endograft components (odds ratio 1.43, 95% CI 1.01 to 2.01, p = 0.043) were predictors of major adverse events. Kaplan-Meier analysis revealed a reduction in late survival among patients with preoperative creatinine >or=1.8 mg/dL (p < 0.001). One- and 5-year intervention-free survivals were 77%+/-3% and 41%+/-6%, respectively. CONCLUSIONS Thoracic endovascular aortic repair represents an effective treatment for a variety of pathologic states. But the risk-benefit analysis for thoracic endovascular aortic repair should carefully consider the extent of disease, pathologic condition, and renal function.

Risk factors for late mortality after endovascular repair of the thoracic aorta

OBJECTIVE This study was conducted to identify risk factors for late mortality after thoracic endovascular aortic repair (TEVAR). METHODS A retrospective analysis of consecutive TEVAR was conducted. Medical record review, telephone contact, or query of the Social Security Death Index was used to determine 30-day and late survival. Late mortality was assessed with respect to patient characteristics at the time of the initial treatment, preoperative laboratory values, pathology, clinical presentation, and treatment adjuncts. Significant univariate predictors of death were entered into a multivariate Cox proportional hazards model. RESULTS From 1998 to 2009, 252 patients (149 men; mean age, 68 years) underwent TEVAR for degenerative thoracic aortic aneurysm (TAA, n = 143), type B dissection (n = 62), mycotic aneurysm (n = 13), traumatic disruption (n = 12), penetrating ulcer or intramural hematoma (n = 10), anastomotic pseudoaneurysm (n = 4), or other pathology (n = 8). The 30-day mortality was 9.5%, with stroke or spinal cord injury in 5.6%. Mean follow-up was 22 +/- 22 months. Kaplan-Meier mean survival was 53 months. Predictors of late mortality by univariate analysis included age (P < .01), cardiac arrhythmia (P = .03), chronic obstructive pulmonary disease (P = .05), aneurysm diameter (P < .01), rupture (P < .01), debranching (P = .02), leukocytosis (white blood cell count > 10.0 x 10(3)/microL; P < .01), albumin, (P < .01), and creatinine > 1.7 mg/dL (P = .01). Multivariate predictors of mortality included rupture (hazard ratio [HR], 3.10; 95% confidence interval [CI], 1.02-9.44; P = .03), debranching (HR, 2.20; 95% CI, 1.09-4.24; P = .03), preoperative leukocytosis (HR, 1.23; 95% CI, 1.09-1.39; P = .001), and aneurysm diameter (HR, 1.02; 95% CI, 1.01-1.03; P = .04). Subgroup analysis of patients undergoing TEVAR for asymptomatic, nonruptured TAA demonstrated that debranching (HR, 2.47; 95% CI, 1.13-5.39; P = .02), White blood cell count (HR, 1.19; 95% CI, 1.01-1.40; P < .04), and aneurysm diameter (HR, 1.03; 95% CI, 1.01-1.05, P < .01) remain independently predictive of late mortality. CONCLUSIONS Preoperative leukocytosis, aneurysm diameter, and concurrent debranching independently predict late mortality irrespective of clinical presentation and may assist in risk stratification.

Characterization of resident surgeon participation during carotid endarterectomy and impact on perioperative outcomes

INTRODUCTION The impact of resident surgeon participation during vascular procedures on postoperative outcomes is incompletely understood. We characterized resident physician participation during carotid endarterectomy (CEA) procedures within the 2005-2009 American College of Surgeons National Surgical Quality Improvement Participant Use Datafile and evaluated associations with procedural characteristics and perioperative adverse events. METHODS CEAs were identified using primary current procedural terminology codes; those performed simultaneously with other major procedures or unknown resident participation status were excluded. Group-wise comparisons based on resident participation status were performed using χ(2) or Fishers exact test for categorical variables and t tests or nonparametric methods for continuous variables. Associations with perioperative adverse events (major = stroke, death, myocardial infarction, or cardiac arrest; minor = peripheral nerve injury, bleeding requiring transfusion, surgical site infection, or wound disruption) were assessed using multivariable logistic regression models adjusting for other known risk factors. RESULTS A total of 25,280 CEA procedures were analyzed, of which residents participated in 13,705 (54.2%), while residents were absent in 11,575 (45.8%). Among CEAs with resident physician participation, resident level was categorized as junior (postgraduate year [PGY] 1-2) in 21.9%, senior (PGY 3-5) in 52.7%, and fellow (PGY ≥6) in 25.3%. Major adverse event rates with and without resident participation were 1.9% versus 2.1%, and minor adverse event rates with and without resident participation were 0.9% versus 1.0%, respectively. In multivariable models, resident physician participation was not associated with perioperative risk for major adverse events (odds ratio [OR], 0.90; 95% confidence interval [CI], 0.75-1.08) or minor adverse events (OR, 0.93; 95% CI, 0.72-1.21). CONCLUSIONS Resident surgeon participation during CEA is not associated with risk of adverse perioperative events.

Thoracic endovascular repair as a safe management strategy for aortobronchial fistulas

OBJECTIVES This study assessed the safety and efficacy of thoracic endovascular aortic repair (TEVAR) in the management of aortobronchial fistulas. METHODS A retrospective review was performed at Emory University Hospital to identify all patients who presented with an aortobronchial fistula. The diagnosis was based on clinical, radiologic, and bronchoscopic findings. Patients who underwent TEVAR as definitive management of these fistulas were identified. Demographics, history of thoracic aorta pathology or intervention, type and number of endografts used, need for reoperation, and clinical and radiologic follow-up data were collected for each individual. RESULTS Between 2000 and 2009, 11 patients received TEVAR as definitive management of aortobronchial fistulas. Technical success was achieved in 10 patients (91%). Six patients (55%) had previously undergone thoracic aortic surgery. A proximal type 1 endoleak developed in one patient after graft deployment and required reintervention for additional graft placement. No intraoperative or 30-day deaths occurred. Postoperative clinical and radiographic assessment was a mean of 8.8 months (range, 1-40 months). For all 10 patients in whom technical success was achieved at the initial operation, no endoleaks were noted at the follow-up CT scan. In addition, no patient required a further intervention. CONCLUSIONS This study represents the largest reported series on the use of TEVAR in the management of aortobronchial fistulas. Supported by postoperative surveillance imaging and clinical evaluation, TEVAR has proven to be a safe and effective management strategy for an otherwise lethal condition. Long-term follow-up data are needed to ascertain the durability of this approach.

GSTP1 Loss Results in Accumulation of Oxidative DNA Base Damage and Promotes Prostate Cancer Cell Survival Following Exposure to Protracted Oxidative Stress

Epigenetic silencing of glutathione S‐transferase π (GSTP1) is a hallmark of transformation from normal prostatic epithelium to adenocarcinoma of the prostate. The functional significance of this loss is incompletely understood. The present study explores the effects of restored GSTP1 expression on glutathione levels, accumulation of oxidative DNA damage, and prostate cancer cell survival following oxidative stress induced by protracted, low dose rate ionizing radiation (LDR).