Perioperative Blood Loss after Preoperative Prostatic Artery Embolization in Patients Undergoing Simple Prostatectomy: A Propensity Score‒Matched Study.

PURPOSE: To assess perioperative blood loss following prostatic artery embolization (PAE) before surgery in patients undergoing simple prostatectomy. METHODS: A retrospective chart review was used to identify 63 patients (mean age, 65.3 ± 8.0 years) with prostatic hypertrophy and severe lower urinary tract symptoms who underwent prostatectomy from September 2014 to December 2019, 18 (28.5%) of whom underwent PAE before surgery. Demographic data, pertinent laboratory results, procedural or operative information, hospital course details, and pathology reports were obtained. A 2:1 propensity score‒matching analysis was performed to compare intraoperative blood loss in patients who underwent prostatectomy alone with intraoperative blood loss in those who first underwent bilateral PAE before surgery. RESULTS: Sixteen (89%) of the 18 patients underwent bilateral PAE before surgery. Thirty-two patients who underwent prostatectomy without embolization before surgery were selected for the 2:1 propensity score‒matched analysis based on age, race, surgery type, prostate gland size, and comorbidities. The mean estimated blood loss (EBL) for prostatectomy alone was 545 ± 380 mL (mean ± standard deviation). There was a statistically significant reduction in the EBL for patients who underwent bilateral PAE (303 ± 227 mL, P < .01). The operative time was also significantly decreased for patients who underwent PAE before surgery (P < .05). For patients who underwent PAE, there were no complications related to the procedure. CONCLUSIONS: Bilateral PAE before surgery appears to be safe and may be effective in reducing perioperative bleeding and operative time.

Preoperative embolization of renal cell carcinoma prior to partial nephrectomy: A systematic review and meta-analysis.

PURPOSE: To evaluate the safety and efficacy of preoperative renal artery embolization of renal cell carcinoma in reducing intraoperative blood loss during subsequent partial nephrectomy through a systematic review and meta-analysis of current literature. MATERIALS AND METHODS: The PubMed database was searched for articles published from 1970 to 2018 describing patients with renal cell carcinoma who underwent partial nephrectomy with and without preoperative embolization of the tumor. Demographic data, procedural techniques, and surgical outcomes were obtained when available. A random-effects meta-analysis was performed to determine estimated blood loss in both groups of patients. RESULTS: The literature search identified 14 relevant articles for systematic review, of which 4 articles provided sufficient data to be included in the meta-analysis. 270 patients (173 males, 97 females) underwent partial nephrectomy for RCC, of whom 222 received pre-operative embolization. There were 48 patients in our cohort that underwent partial nephrectomy for RCC without preoperative embolization. Random-effects meta-analysis demonstrated a significant difference between EBL in patients undergoing RAE prior to partial nephrectomy vs partial nephrectomy without preoperative embolization, with EBL of 154.0 ± 22.6 mL (n = 222) and 353.4 ± 69.6 mL (n = 478), respectively (p < 0.0001). Major complications occurred in 4.9% of patients undergoing pre-operative embolization followed by partial nephrectomy, whereas major complications occurred in 10.9% of patients undergoing partial nephrectomy without embolization (p = 0.01). Minor complications occurred in 5.8% of patients undergoing embolization and partial nephrectomy and in 19.0% of patients undergoing partial nephrectomy without embolization (p < 0.0001). CONCLUSION: Renal artery embolization prior to surgical resection of renal cell carcinoma is safe and significantly reduces intraoperative blood loss in patients undergoing partial nephrectomy.

Trauma CT evaluation prior to selective angiography in patients with traumatic injuries: negative predictive power and factors affecting its utility.

PURPOSE: To evaluate the predictive power of arterial injury detected on contrast-enhanced CT (trauma CT (tCT)) imaging obtained prior to selective angiography for treatment of patients with traumatic abdominal and pelvic injuries. MATERIALS AND METHODS: A retrospective chart review was performed of all patients who underwent angiography after undergoing contrast-enhanced CT imaging for the evaluation/treatment of traumatic injuries to the abdomen and pelvis between March 2014 and September 2018. Data collection included demographics, pertinent history and physical findings, CT and angiography findings, treatment information, and outcomes. RESULTS: Eighty-nine (63 males, mean age = 45.8 ± 20.5 years) patients that were found to have 102 traumatic injuries on tCT and subsequently underwent angiography met inclusion criteria for this study. Sixty-four injuries demonstrated evidence of traumatic vascular injury on initial tCT. A negative tCT was able to predict subsequent negative angiography in 83% of cases (negative predictive power = 83%). The ability of tCT to rule out a positive finding on subsequent angiography was also 83% (sensitivity = 83%). The average systolic blood pressure and hemoglobin concentration at the time of tCT were higher in patients who had positive tCT than in patients with negative tCT (p < 0.05 and p < 0.01, respectively). The average time to angiography was greater in patients whom had subsequent negative angiography than the patients who had subsequent positive angiography (p < 0.05). CONCLUSION: Contrast-enhanced CT imaging may be able to help stratify patients who may have subsequent negative angiograms. Hemodynamic factors may affect sensitivity of tCT. Shorter time to angiography may increase the chance of identifying the injury on subsequent angiography.

Fluorine-18-Labeled Thymidine Positron Emission Tomography (FLT-PET) as an Index of Cell Proliferation after Pharmacological Ascorbate-Based Therapy.

Pharmacological ascorbate (AscH(-)) induces cytotoxicity and oxidative stress selectively in pancreatic cancer cells compared with normal cells. Positron emission tomography (PET) with the thymidine analog 3'-deoxy-3'-((18)F) fluorothymidine (FLT) enables noninvasive imaging and quantification of the proliferation fraction of tumors. We hypothesized that the rate of tumor proliferation determined by FLT-PET imaging, would be inversely proportional to tumor susceptibility to pharmacological AscH(-)-based treatments. Indeed, there was decreased FLT uptake in human pancreatic cancer cells treated with AscH(-) in vitro, and this effect was abrogated by co-treatment with catalase. In separate experiments, cells were treated with AscH(-), ionizing radiation or a combination of both. These studies demonstrated that combined AscH(-) and radiation treatment resulted in a significant decrease in FLT uptake that directly correlated with decreased clonogenic survival. MicroPET (18)F-FLT scans of mice with pre-established tumors demonstrated that AscH(-) treatment induced radiosensitization compared to radiation treatment alone. These data support testing of pharmacological ascorbate as a radiosensitizer in pancreatic cancer as well as the use of FLT-PET to monitor response to therapy.

Treatment of Pancreatic Cancer with Pharmacological Ascorbate.

The prognosis for patients diagnosed with pancreatic cancer remains dismal, with less than 3% survival at 5 years. Recent studies have demonstrated that high-dose, intravenous pharmacological ascorbate (ascorbic acid, vitamin C) induces cytotoxicity and oxidative stress selectively in pancreatic cancer cells vs. normal cells, suggesting a promising new role of ascorbate as a therapeutic agent. At physiologic concentrations, ascorbate functions as a reducing agent and antioxidant. However, when pharmacological ascorbate is given intravenously, it is possible to achieve millimolar plasma concentration. At these pharmacological levels, and in the presence of catalytic metal ions, ascorbate can induce oxidative stress through the generation of hydrogen peroxide (H2O2). Recent in vitro and in vivo studies have demonstrated ascorbate oxidation occurs extracellularly, generating H2O2 flux into cells resulting in oxidative stress. Pharmacologic ascorbate also inhibits the growth of pancreatic tumor xenografts and displays synergistic cytotoxic effects when combined with gemcitabine in pancreatic cancer. Phase I trials of pharmacological ascorbate in pancreatic cancer patients have demonstrated safety and potential efficacy. In this chapter, we will review the mechanism of ascorbate-induced cytotoxicity, examine the use of pharmacological ascorbate in treatment and assess the current data supporting its potential as an adjuvant in pancreatic cancer.

Pharmacological Ascorbate Radiosensitizes Pancreatic Cancer.

The toxicity of pharmacologic ascorbate is mediated by the generation of H2O2 via the oxidation of ascorbate. Because pancreatic cancer cells are sensitive to H2O2 generated by ascorbate, they would also be expected to become sensitized to agents that increase oxidative damage such as ionizing radiation. The current study demonstrates that pharmacologic ascorbate enhances the cytotoxic effects of ionizing radiation as seen by decreased cell viability and clonogenic survival in all pancreatic cancer cell lines examined, but not in nontumorigenic pancreatic ductal epithelial cells. Ascorbate radiosensitization was associated with an increase in oxidative stress-induced DNA damage, which was reversed by catalase. In mice with established heterotopic and orthotopic pancreatic tumor xenografts, pharmacologic ascorbate combined with ionizing radiation decreased tumor growth and increased survival, without damaging the gastrointestinal tract or increasing systemic changes in parameters indicative of oxidative stress. Our results demonstrate the potential clinical utility of pharmacologic ascorbate as a radiosensitizer in the treatment of pancreatic cancer.

Manganoporphyrins and ascorbate enhance gemcitabine cytotoxicity in pancreatic cancer.

Pharmacological ascorbate (AscH(-)) selectively induces cytotoxicity in pancreatic cancer cells vs normal cells via the generation of extracellular hydrogen peroxide (H2O2), producing double-stranded DNA breaks and ultimately cell death. Catalytic manganoporphyrins (MnPs) can enhance ascorbate-induced cytotoxicity by increasing the rate of AscH(-) oxidation and therefore the rate of generation of H2O2. We hypothesized that combining MnPs and AscH(-) with the chemotherapeutic agent gemcitabine would further enhance pancreatic cancer cell cytotoxicity without increasing toxicity in normal pancreatic cells or other organs. Redox-active MnPs were combined with AscH(-) and administered with or without gemcitabine to human pancreatic cancer cell lines, as well as immortalized normal pancreatic ductal epithelial cells. The MnPs MnT2EPyP (Mn(III)meso-tetrakis(N-ethylpyridinium-2-yl) porphyrin pentachloride) and MnT4MPyP (Mn(III)tetrakis(N-methylpyridinium-4-yl) porphyrin pentachloride) were investigated. Clonogenic survival was significantly decreased in all pancreatic cancer cell lines studied when treated with MnP + AscH(-) + gemcitabine, whereas nontumorigenic cells were resistant. The concentration of ascorbate radical (Asc(•-), an indicator of oxidative flux) was significantly increased in treatment groups containing MnP and AscH(-). Furthermore, MnP + AscH(-) increased double-stranded DNA breaks in gemcitabine-treated cells. These results were abrogated by extracellular catalase, further supporting the role of the flux of H2O2. In vivo growth was inhibited and survival increased in mice treated with MnT2EPyP, AscH(-), and gemcitabine without a concomitant increase in systemic oxidative stress. These data suggest a promising role for the use of MnPs in combination with pharmacologic AscH(-) and chemotherapeutics in pancreatic cancer.

Extracellular superoxide dismutase suppresses hypoxia-inducible factor-1α in pancreatic cancer.

Hypoxia-inducible factor-1 (HIF-1) is a heterodimeric transcription factor that governs cellular responses to reduced oxygen availability by mediating crucial homeostatic processes and is a major survival determinant for tumor cells growing in a low-oxygen environment. Clinically, HIF-1α seems to be important in pancreatic cancer, as HIF-1α correlates with metastatic status of the tumor. Extracellular superoxide dismutase (EcSOD) inhibits pancreatic cancer cell growth by scavenging nonmitochondrial superoxide. We hypothesized that EcSOD overexpression leads to changes in the O2(-)/H2O2 balance modulating the redox status affecting signal transduction pathways. Both transient and stable overexpression of EcSOD suppressed the hypoxic accumulation of HIF-1α in human pancreatic cancer cells. This suppression of HIF-1α had a strong inverse correlation with levels of EcSOD protein. Coexpression of the hydrogen peroxide-removing protein glutathione peroxidase did not prevent the EcSOD-induced suppression of HIF-1α, suggesting that the degradation of HIF-1α observed with high EcSOD overexpression is possibly due to a low steady-state level of superoxide. Hypoxic induction of vascular endothelial growth factor (VEGF) was also suppressed with increased EcSOD. Intratumoral injections of an adenoviral vector containing the EcSOD gene into preestablished pancreatic tumors suppressed both VEGF levels and tumor growth. These results demonstrate that the transcription factor HIF-1α and its important gene target VEGF can be modulated by the antioxidant enzyme EcSOD.

Electron spin-echo envelope modulation (ESEEM) reveals water and phosphate interactions with the KcsA potassium channel.

Electron spin-echo envelope modulation (ESEEM) spectroscopy is a well-established technique for the study of naturally occurring paramagnetic metal centers. The technique has been used to study copper complexes, hemes, enzyme mechanisms, micellar water content, and water permeation profiles in membranes, among other applications. In the present study, we combine ESEEM spectroscopy with site-directed spin labeling (SDSL) and X-ray crystallography in order to evaluate the technique's potential as a structural tool to describe the native environment of membrane proteins. Using the KcsA potassium channel as a model system, we demonstrate that deuterium ESEEM can detect water permeation along the lipid-exposed surface of the KcsA outer helix. We further demonstrate that (31)P ESEEM is able to identify channel residues that interact with the phosphate headgroup of the lipid bilayer. In combination with X-ray crystallography, the (31)P data may be used to define the phosphate interaction surface of the protein. The results presented here establish ESEEM as a highly informative technique for SDSL studies of membrane proteins.

Flagellar membrane localization via association with lipid rafts.

The eukaryotic flagellar membrane has a distinct composition from other domains of the plasmalemma. Our work shows that the specialized composition of the trypanosome flagellar membrane reflects increased concentrations of sterols and saturated fatty acids, correlating with direct observation of high liquid order by laurdan fluorescence microscopy. These findings indicate that the trypanosome flagellar membrane possesses high concentrations of lipid rafts: discrete regions of lateral heterogeneity in plasma membranes that serve to sequester and organize specialized protein complexes. Consistent with this, a dually acylated Ca(2+) sensor that is concentrated in the flagellum is found in detergent-resistant membranes and mislocalizes if the lipid rafts are disrupted. Detergent-extracted cells have discrete membrane patches localized on the surface of the flagellar axoneme, suggestive of intraflagellar transport particles. Together, these results provide biophysical and biochemical evidence to indicate that lipid rafts are enriched in the trypanosome flagellar membrane, providing a unique mechanism for flagellar protein localization and illustrating a novel means by which specialized cellular functions may be partitioned to discrete membrane domains.

Inhibition of geranylgeranyl diphosphate synthase by bisphosphonates and diphosphates: a potential route to new bone antiresorption and antiparasitic agents.

We report the inhibition of a human recombinant geranylgeranyl diphosphate synthase (GGPPSase) by 23 bisphosphonates and six azaprenyl diphosphates. The IC50 values range from 140 nM to 690 microM. None of the nitrogen-containing bisphosphonates that inhibit farnesyl diphosphate synthase were effective in inhibiting the GGPPSase enzyme. Using three-dimensional quantitative structure-activity relationship/comparative molecular field analysis (CoMFA) methods, we find a good correlation between experimental and predicted activity: R2 = 0.938, R(cv)2 = 0.900, R(bs)2 = 0.938, and F-test = 86.8. To test the predictive utility of the CoMFA approach, we used three training sets of 25 compounds each to generate models to predict three test sets of three compounds. The rms pIC50 error for the nine predictions was 0.39. We also investigated the pharmacophore of these GGPPSase inhibitors using the Catalyst method. The results demonstrated that Catalyst predicted the pIC50 values for the nine test set compounds with an rms error of 0.28 (R2 between experimental and predicted activity of 0.948).