Benefits of successful percutaneous coronary intervention in chronic total occlusion patients with diabetes.

BACKGROUND: Diabetes was commonly seen in chronic total occlusion (CTO) patients but data regarding the impact of successful percutaneous coronary intervention (PCI) on clinical outcome of CTO patients with diabetes was controversial. And importantly, no studies have compared quality of life (QOL) after CTO-PCI in patients with and without diabetes. METHODS: Consecutive patients undergoing elective CTO-PCI were prospectively enrolled from Apr. 2018 to May 2021. Patients were subdivided into 2 groups: Diabetes and No Diabetes. Detailed baseline characteristics, assessment of symptoms and QOL, angiographic and procedural details, in-hospital complications, and 1 month and 1 year follow-up data were collected. These data were analyzed accordingly for risk predictors of clinical outcome in patients who have diabetes and received successful CTO-PCI. RESULTS: A total of 1076 patients underwent CTO-PCI attempts. Diabetes was present in 374 (34.76%) patients, who had more hypertension, previous PCI and stroke. Regarding the coronary lesions, diabetic patients suffered more LCX lesion, multivessel disease, number of lesions per patient, blunt stump, calcification and higher J-CTO score (p < 0.05). In-hospital major adverse cardiac event (MACE) (4.13% vs. 5.35%; p = 0.362) was similar in the two groups. At 1 month and 1 year follow-up after successful CTO-PCI, the incidence of MACE and all-cause mortality were also similar in the two groups (p > 0.05). Number of lesions per patient was an independent risk factor of MACE and all-cause mortality (p < 0.001) 1 year after successful CTO-PCI. Symptom and QOL were markedly improved regardless of diabetes both at 1 month and 1 year follow-up, and importantly, patients with diabetes showed similar degrees of improvement to those without diabetes (P > 0.05). CONCLUSIONS: Successful CTO-PCI could represent an effective strategy improving clinical outcome, symptoms and QOL in CTO patients with diabetes.

The Feasibility and Long-Term Outcomes of the Crossboss/Stingray for Treating Coronary Chronic Total Occlusions Lesions with Distal Diffuse Disease Landing Zone.

BACKGROUND: The feasibility and long-term outcomes of the CrossBoss/Stingray for treating coronary chronic total occlusions (CTO) with distal diffuse disease landing zone remain unclear. METHODS: Consecutive CTO patients with distal diffuse lesions that underwent percutaneous coronary intervention by the CrossBoss/Stingray system at Xijing Hospital from April 2016 to October 2020, were included. Patients were analyzed by two groups according to the extent of stenosis in the distal landing zone: 50%-70% stenosis (moderate stenosis group) and >70% stenosis (severe stenosis group). The primary efficacy outcome was technical success, defined as the frequency of true lumen guidewire placement distal to the CTO. The composite endpoint of all-cause death, any stroke, or any revascularization was also explored. RESULTS: A total of 91 consecutive patients were included, with 32 patients in the moderate stenosis group and 59 patients in the severe stenosis group. The mean J-CTO score was 2.5 ± 1.1. The technical success rate was 79.1% (72/91) in the overall population and was similar between the 2 groups: 78.1% (25/32) and 79.7% (47/59) (p = 0.608). No coronary perforation occurred. With a median follow-up of 29 months (IQR: 53-92), the estimated rate of the composite endpoint of all-cause death, any stroke, or any revascularization was 50.4% (all-cause death: 16.6%, any stroke: 1.1%, any revascularization: 36.5%) in the overall population. No significant difference was observed in the rate of the composite endpoint between the moderate stenosis group and the severe stenosis group (45.1% vs. 54.3%, respectively, p = 0.797). CONCLUSIONS: In CTO lesions with distal diffuse disease landing zone, the technical success rates of CrossBoss/Stingray and the long-term clinical outcomes were not significantly different between the moderate stenosis group (50%-70%) and the severe stenosis group (>70%). However, the relatively high rate of long-term clinical outcomes, especially any revascularization, warrants further investigations on this indication in future studies.

Notch3/Akt signaling contributes to OSM-induced protection against cardiac ischemia/reperfusion injury.

Oncostatin M (OSM) exhibits many unique biological activities by activating the Oß receptor. However, its role in myocardial ischemia/reperfusion injury (I/R injury) in mice remains unknown. We investigated whether Notch3/Akt signaling is involved in the regulation of OSM-induced protection against cardiac I/R injury. The effects of OSM were assessed in mice that underwent myocardial I/R injury by OSM treatment or by genetic deficiency of the OSM receptor Oß. We investigated its effects on cardiomyocyte apoptosis and mitochondrial biogenesis and whether Notch3/Akt signaling was involved in the regulation of OSM-induced protection against cardiac I/R injury. The mice underwent 30 min of ischemia followed by 3 h of reperfusion and were randomized to be treated with Notch3 siRNA (siNotch3) or lentivirus carrying Notch3 cDNA (Notch3) 72 h before coronary artery ligation. Myocardial infarct size, cardiac function, cardiomyocyte apoptosis and mitochondria morphology in mice that underwent cardiac I/R injury were compared between groups. OSM alleviated cardiac I/R injury by inhibiting cardiomyocyte apoptosis through promotion of Notch3 production, thus activating the PI3K/Akt pathway. OSM enhanced mitochondrial biogenesis and mitochondrial function in mice subjected to cardiac I/R injury. In contrast, OSM receptor Oß knock out exacerbated cardiac I/R injury, decreased Notch3 production, enhanced cardiomyocyte apoptosis, and impaired mitochondrial biogenesis in cardiac I/R injured mice. The mechanism of OSM on cardiac I/R injury is partly mediated by the Notch3/Akt pathway. These results suggest a novel role of Notch3/Akt signaling that contributes to OSM-induced protection against cardiac I/R injury.

Computing intracoronary blood flow rate under incomplete boundary conditions: Combing coronary anatomy and fractional flow reserve.

BACKGROUND: Accurate measurement of intracoronary blood flow rate is of great significance for the diagnosis of ischemic heart disease (IHD). Computational fluid dynamic (CFD) method, combining coronary angiography images and fractional flow reserve (FFR), provides a new way to calculate the mean flow rate. However, due to the incomplete boundary conditions obtained by FFR, side branches were ignored which was likely to have a significant impact on the accuracy. In this paper, a novel CFD based method for calculating the mean intracoronary flow rate under incomplete pressure boundary conditions was proposed, in order to improve the accuracy by including the side branches. METHODS: A pressure-flow curve based flow resistance model was employed to model resistance of the epicardial arteries. A series of steady flow simulations were performed to extract the parameters of the flow resistance model, which implicitly specified constraints for splitting flow between branches and thus enabled the mean intracoronary blood flow rate to be calculated in two or more branches under incomplete pressure boundary conditions. Simulation experiments were designed to validate the proposed method in both idealized and reconstructed 3D models of coronary branches, and the impact of the assumed coefficient of the Murray's Law for splitting flow between branches was also investigated. RESULTS: The mean percentage error of the proposed method was +2.05%±0.04% for idealized models and +2.24%±0.01% for reconstructed models, and it was much lower than that of the method ignoring side branches (+38.48%±10.45% for idealized models and +30.54%±6.12% for reconstructed models). When the assumed coefficient of the Murray's Law was inconsistent with the real blood flow condition, the percentage errors still maintained less than about 3.00%. CONCLUSIONS: The proposed method provided an easy and accurate way to measure the mean intracoronary flow rate and would facilitate the accurate diagnosis of IHD.

Improvement of Symptoms and Quality of Life After Successful Percutaneous Coronary Intervention for Chronic Total Occlusion in Elderly Patients.

Background Data regarding the impact of successful chronic total occlusion treated with percutaneous coronary intervention (CTO-PCI) on symptoms and quality of life (QOL) in elderly patients (≥75 years) are unknown. This prospective study aimed to assess whether successful CTO-PCI could improve the symptoms and QOL in elderly patients (≥75 years). Methods and Results Consecutive patients who underwent elective CTO-PCI were prospectively enrolled and subdivided into 3 groups based on age: age<65 years, 65 years≤age<75 years, and age≥75 years. The primary outcomes included symptoms, as assessed with the New York Heart Association functional class and Seattle Angina Questionnaire, and QOL, as assessed with the 12-Item Short-Form Health Survey questionnaire, at baseline, 1 month, and 1 year after successful CTO-PCI. Of 1076 patients with CTO, 101 were age≥75 years (9.39%). Hemoglobin, estimated glomerular filtration rate, and left ventricular ejection fraction levels all decreased with increasing age, and NT-proBNP (N-terminal pro-B-type natriuretic peptide) increased. The proportion of dyspnea and coronary lesions, including multivessel disease, multi-CTO lesion, and calcification were higher in elderly patients. Procedural success rate, intraprocedural complications, and in-hospital major adverse cardiac events were not statistically different in the 3 groups. Importantly, symptoms, including dyspnea and angina, were markedly improved regardless of age at 1-month and 1-year follow-up (P<0.05). Likewise, successful CTO-PCI significantly improved QOL at 1-month and 1-year follow-up (P<0.01). Additionally, the incidence of major adverse cardiac events and all-cause mortality at 1-month and 1-year follow-up was not statistically different in the 3 groups. Conclusions Successful PCI was beneficial and feasible to improve symptoms and QOL in patients ≥75 years of age with CTO.

Elevated branched-chain amino acid promotes atherosclerosis progression by enhancing mitochondrial-to-nuclear H2O2-disulfide HMGB1 in macrophages.

As the essential amino acids, branched-chain amino acid (BCAA) from diets is indispensable for health. BCAA supplementation is often recommended for patients with consumptive diseases or healthy people who exercise regularly. Latest studies and ours reported that elevated BCAA level was positively correlated with metabolic syndrome, diabetes, thrombosis and heart failure. However, the adverse effect of BCAA in atherosclerosis (AS) and its underlying mechanism remain unknown. Here, we found elevated plasma BCAA level was an independent risk factor for CHD patients by a human cohort study. By employing the HCD-fed ApoE-/- mice of AS model, ingestion of BCAA significantly increased plaque volume, instability and inflammation in AS. Elevated BCAA due to high dietary BCAA intake or BCAA catabolic defects promoted AS progression. Furthermore, BCAA catabolic defects were found in the monocytes of patients with CHD and abdominal macrophages in AS mice. Improvement of BCAA catabolism in macrophages alleviated AS burden in mice. The protein screening assay revealed HMGB1 as a potential molecular target of BCAA in activating proinflammatory macrophages. Excessive BCAA induced the formation and secretion of disulfide HMGB1 as well as subsequent inflammatory cascade of macrophages in a mitochondrial-nuclear H2O2 dependent manner. Scavenging nuclear H2O2 by overexpression of nucleus-targeting catalase (nCAT) effectively inhibited BCAA-induced inflammation in macrophages. All of the results above illustrate that elevated BCAA promotes AS progression by inducing redox-regulated HMGB1 translocation and further proinflammatory macrophage activation. Our findings provide novel insights into the role of animo acids as the daily dietary nutrients in AS development, and also suggest that restricting excessive dietary BCAA consuming and promoting BCAA catabolism may serve as promising strategies to alleviate and prevent AS and its subsequent CHD.

18F-radiolabeled analogs of exendin-4 for PET imaging of GLP-1 in insulinoma.

PURPOSE: Glucagon-like peptide type 1 (GLP-1) is an incretin peptide that augments glucose-stimulated insulin release following oral consumption of nutrients. Its message is transmitted via a G protein-coupled receptor called GLP-1R, which is colocalized with pancreatic ß-cells. The GLP-1 system is responsible for enhancing insulin release, inhibiting glucagon production, inhibiting hepatic gluconeogenesis, inhibiting gastric mobility, and suppression of appetite. The abundance of GLP-1R in pancreatic ß-cells in insulinoma, a cancer of the pancreas, and the activity of GLP-1 in the cardiovascular system have made GLP-1R a target for molecular imaging. METHODS: We prepared (18)F radioligands for GLP-1R by the reaction of [(18)F]FBEM, a maleimide prosthetic group, with [Cys(0)] and [Cys(40)] analogs of exendin-4. The binding affinity, cellular uptake and internalization, in vitro stability, and uptake and specificity of uptake of the resulting compounds were determined in an INS-1 xenograft model in nude mice. RESULTS: The [(18)F]FBEM-[Cys(x)]-exendin-4 analogs were obtained in good yield (34.3 ± 3.4%, n = 11), based on the starting compound [(18)F]FBEM), and had a specific activity of 45.51 ± 16.28 GBq/µmol (1.23 ± 0.44 Ci/µmol, n = 7) at the end of synthesis. The C-terminal isomer, [(18)F]FBEM-[Cys(40)]-exendin-4, had higher affinity for INS-1 tumor cells (IC(50) 1.11 ± 0.057 nM) and higher tumor uptake (25.25 ± 3.39 %ID/g at 1 h) than the N-terminal isomer, [(18)F]FBEM-[Cys(0)]-exendin-4 (IC(50) 2.99 ± 0.06 nM, uptake 7.20 ± 1.26 %ID/g at 1 h). Uptake of both isomers into INS-1 tumor, pancreas, stomach, and lung could be blocked by preinjection of nonradiolabeled [Cys(x)]-exendin-4 (p < 0.05). CONCLUSION: [(18)F]FBEM-[Cys(40)]-exendin-4 and [(18)F]FBEM-[Cys(0)]-exendin-4 have high affinity for GLP-1R and display similar in vitro cell internalization. The higher uptake into INS-1 xenograft tumors exhibited by [(18)F]FBEM-[Cys(40)]-exendin-4 suggests that this compound would be the better tracer for imaging GLP-1R.

PET imaging of angiogenesis after myocardial infarction/reperfusion using a one-step labeled integrin-targeted tracer 18F-AlF-NOTA-PRGD2.

PURPOSE: The α(v)ß(3) integrin represents a potential target for noninvasive imaging of angiogenesis. The purpose of this study was to evaluate a novel one-step labeled integrin α(v)ß(3)-targeting positron emission tomography (PET) probe, (18)F-AlF-NOTA-PRGD2, for angiogenesis imaging in a myocardial infarction/reperfusion (MI/R) animal model. METHODS: Male Sprague-Dawley rats underwent 45-min transient left coronary artery occlusion followed by reperfusion. The myocardial infarction was confirmed by ECG, (18)F-fluorodeoxyglucose (FDG) imaging, and cardiac ultrasound. In vivo PET imaging was used to determine myocardial uptake of (18)F-AlF-NOTA-PRGD2 at different time points following reperfusion. The control peptide RAD was labeled with a similar procedure and used to confirm the specificity. Ex vivo autoradiographic analysis and CD31/CD61 double immunofluorescence staining were performed to validate the PET results. RESULTS: Myocardial origin of the (18)F-AlF-NOTA-PRGD2 accumulation was confirmed by (18)F-FDG and autoradiography. PET imaging demonstrated increased focal accumulation of (18)F-AlF-NOTA-PRGD2 in the infarcted area which started at day 3 (0.28 ± 0.03%ID/g, p < 0.05) and peaked between 1 and 3 weeks (0.59 ± 0.16 and 0.55 ± 0.13%ID/g, respectively). The focal accumulation decreased but still kept at a higher level than the sham group after 4 months of reperfusion (0.31 ± 0.01%ID/g, p < 0.05). Pretreatment with unlabeled arginine-glycine-aspartic acid (RGD) peptide significantly decreased tracer uptake, indicating integrin specificity of this tracer. At 1 week after MI/R, uptake of the control tracer (18)F-AlF-NOTA-RAD that does not bind to integrin, in the infarcted area, was only 0.21 ± 0.01%ID/g. Autoradiographic imaging showed the same trend of uptake in the myocardial infarction area. The time course of focal tracer uptake was consistent with the pattern of vascular density and integrin ß(3) expression as measured by CD31 and CD61 immunostaining analysis. CONCLUSION: PET imaging using one-step labeled (18)F-AlF-NOTA-PRGD2 allows noninvasive visualization of ischemia/reperfusion-induced myocardial angiogenesis longitudinally. The favorable in vivo kinetics and easy production method of this integrin-targeted PET tracer facilitates its future clinical translation for lesion evaluation and therapy response monitoring in patients with occlusive cardiovascular diseases.

Evaluation of fluorine-labeled gastrin-releasing peptide receptor (GRPR) agonists and antagonists by LC/MS.

An LC/MS method was used to evaluate 2-fluoropropionyl (FP) and 4-fluorobenzoyl (FB) modified bombsin peptides: GRPR agonist [Aca-QWAVGHLM-NH(2)] and antagonist [fQWAVGHL-NHEt], and their hydrophilic linker modified counterparts with the attachment of GGGRDN sequence. This study developed strategies to evaluate the in vitro receptor mediated cell uptake and metabolic profile of the various GRPR agonists and antagonists. We identified the metabolites produced by rat hepatocytes and quantitatively analyzed the uptake and internalization of the ligands in PC-3 human prostate cancer cells. The major metabolites of both GRPR agonists and antagonists were the result of peptide bond hydrolysis between WA and AV. The agonists also formed a unique metabolite resulting from hydrolysis of the C-terminal amide. The antagonists showed significantly higher stability against metabolism compared to the agonists in rat hepatocytes. The directly modified agonists (FP-BBN and FB-BBN) had higher internalization with similar cell binding compared to the unmodified agonist (BBN), whereas the hydrophilic linker modified agonists (G-BBN and FG-BBN) had much lower total cell uptake. The labeled antagonists (FP-NBBN, FB-NBBN, G-NBBN and FP-G-NBBN) displayed lower internalization. The optimal imaging agent will depend on the interplay of ligand metabolism, cellular uptake, and internalization in vivo.

Chimeric ferritin nanocages for multiple function loading and multimodal imaging.

Nanomaterials provide large surface areas, relativeto their volumes, on which to load functions. One challenge, however, has been to achieve precise control in loading multiple functionalities. Traditional bioconjugation techniques, which randomly target the surface functional groups of nanomaterials, have been found increasingly inadequate for such control, which is a drawback that may substantially slow down or prohibit the translational efforts. In the current study, we evaluated ferritin nanocages as candidate nanoplatforms for multifunctional loading. Ferritin nanocages can be either genetically or chemically modified to impart functionalities to their surfaces, and metal cations can be encapsulated in their interiors by association with metal binding sites. Moreover, different types of ferritin nanocages can be disassembled under acidic condition and reassembled at pH of 7.4, providing a facile way to achieve function hybridization. We were able to use combinations of these unique properties to produce a number of multifunctional ferritin nanostructures with precise control of their composition. We then studied these nanoparticles, both in vitro and in vivo, to evaluate their potential suitability as multimodality imaging probes. A good tumor targeting profile was observed, which was attributable to both the enhanced permeability and retention (EPR) effect and biovector mediated targeting. This, in combination with the generalizability of the function loading techniques, promises ferritin particles as a powerful nanoplatfom in the era of nanomedicine.

Percutaneous coronary intervention improves quality of life of patients with chronic total occlusion and low estimated glomerular filtration rate.

Background: A low estimated glomerular filtration rate (eGFR <90 mL/min/1.73 m2) is widely recognized as a risk factor for major adverse cardiac events (MACE) after percutaneous coronary intervention (PCI) for chronic total occlusion (CTO). However, the impact of successful CTO-PCI on quality of life (QOL) of patients with low eGFR remains unknown. Objectives: The aim of this prospective study was to assess the QOL of CTO patients with low eGFR after successful PCI. Methods: Consecutive patients undergoing elective CTO-PCI were prospectively enrolled and subdivided into four groups: eGFR ≥90 mL/min/1.73 m2 (n = 410), 90 > eGFR ≥ 60 mL/min/1.73 m2 (n = 482), 60 > eGFR ≥ 30 mL/min/1.73 m2 (n = 161), and eGFR <30 mL/min/1.73 m2 (n = 23). The primary outcomes included QOL, as assessed with the European Quality of Life-5 Dimensions (EQ-5D) questionnaire, and symptoms, as assessed with the Rose Dyspnea Scale (RDS) and Seattle Angina Questionnaire (SAQ), at 1 month and 1 year after successful PCI. Results: With the decline of eGFR, CTO patients were more likely to present with comorbidities of hypertension, diabetes, hyperuricemia, and previous stroke, in addition to lower hemoglobin levels and left ventricular ejection fraction (p < 0.05). Low eGFR was associated with greater incidences of in-hospital pericardiocentesis, major bleeding, acute renal failure, and subcutaneous hematoma, but not in-hospital MACE (p < 0.05). Symptoms of dyspnea and angina were alleviated in all CTO patients with eGFR ≥30 mL/min/1.73 m2 at 1 month and 1 year after successful CTO-PCI, but only at 1 month for those with eGFR <30 mL/min/1.73 m2 (p < 0.01). Importantly, QOL was markedly improved at 1 month and 1 year after successful PCI (p < 0.01), notably at a similar degree between patients with low eGFR and those with normal eGFR (p > 0.05). Conclusion: Successful PCI effectively improved symptoms and QOL of CTO patients with low eGFR.

Comparative Effectiveness and Safety of Ticagrelor Versus Clopidogrel for Elderly Chinese Patients Undergoing Percutaneous Coronary Intervention: A Single-Center Retrospective Cohort Study.

BACKGROUND: Taking ischemic and bleeding risks into consideration, insufficient data exist on dual antiplatelet therapy after percutaneous coronary intervention in elderly Chinese patients with coronary artery disease. OBJECTIVE: We aimed to investigate the effectiveness and safety of ticagrelor in comparison with clopidogrel on a background of aspirin for elderly Chinese patients with coronary artery disease 12 months after percutaneous coronary intervention. METHODS: A single-center retrospective cohort study was conducted. Selected from patients with coronary artery disease aged ≥ 75 years from January 2010 to July 2019, 908 eligible subjects receiving dual antiplatelet therapy after percutaneous coronary intervention for up to 12 months were consecutively enrolled in the study. The included patients received ticagrelor in combination with aspirin (n = 264) or clopidogrel in combination with aspirin (n = 644). Effectiveness endpoints were evaluated by the major adverse cardiovascular events, encompassing all-cause death, non-fatal myocardial infarction, and clinically driven revascularization. The safety endpoints were recorded as the incidence of Bleeding Academic Research Consortium bleeding. RESULTS: The patients who were treated with ticagrelor were slightly younger than those who were treated with clopidogrel (79.1 ± 3.7 vs 80.7 ± 4.5 years, p < 0.01). The ticagrelor cohort contained a higher percentage of patients undergoing a prior percutaneous coronary intervention (37.9% vs 24.5%, p < 0.01), and a lower percentage of smokers (19.3% vs 27.2%, p < 0.05), compared with the clopidogrel cohort. The levels of glucose, total cholesterol, and low-density lipoprotein-cholesterol in the ticagrelor group were higher while the level of triglycerides and high-density lipoprotein-cholesterol were lower (p < 0.05) than those in the clopidogrel group. Left main percutaneous coronary intervention was performed more frequently among the ticagrelor-treated patients (23.5% vs 9.3%, p < 0.01), while patients in the clopidogrel group underwent more left circumflex percutaneous coronary intervention (34.3% vs 23.1%, p < 0.01). We found that ticagrelor was associated with a lower incidence of major adverse cardiovascular events than clopidogrel using the inverse probability of treatment weighting model (odds ratio, 0.493; 95% confidence interval 0.356-0.684). There was no difference in terms of the risk of Bleeding Academic Research Consortium bleeding between the two groups (p > 0.05). CONCLUSIONS: Ticagrelor was associated with a lower incidence of major adverse cardiovascular events than clopidogrel at 12 months in elderly Chinese patients with coronary artery disease, without a significant increase of Bleeding Academic Research Consortium bleeding events.

Imaging tumor endothelial marker 8 using an 18F-labeled peptide.

PURPOSE: Tumor endothelial marker 8 (TEM8) has been reported to be upregulated in both tumor cells and tumor-associated endothelial cells in several cancer types. TEM8 antagonists and TEM8-targeted delivery of toxins have been developed as effective cancer therapeutics. The ability to image TEM8 expression would be of use in evaluating TEM8-targeted cancer therapy. METHODS: A 13-meric peptide, KYNDRLPLYISNP (QQM), identified from the small loop in domain IV of protective antigen of anthrax toxin was evaluated for TEM8 binding and labeled with 18F for small-animal PET imaging in both UM-SCC1 head-and-neck cancer and MDA-MB-435 melanoma models. RESULTS: A modified ELISA showed that QQM peptide bound specifically to the extracellular vWA domain of TEM8 with an IC50 value of 304 nM. Coupling 4-nitrophenyl 2-(18)F-fluoropropionate with QQM gave almost quantitative yield and a high specific activity (79.2±7.4 TBq/mmol, n=5) of 18F-FP-QQM at the end of synthesis. 18F-FP-QQM showed predominantly renal clearance and had significantly higher accumulation in TEM8 high-expressing UM-SCC1 tumors (2.96±0.84 %ID/g at 1 h after injection) than TEM8 low-expressing MDA-MB-435 tumors (1.38±0.56 %ID/g at 1 h after injection). CONCLUSION: QQM peptide bound specifically to the extracellular domain of TEM8. 18F-FP-QQM peptide tracer would be a promising lead compound for measuring TEM8 expression. Further efforts to improve the affinity and specificity of the tracer and to increase its metabolic stability are warranted.

PET imaging of early response to the tyrosine kinase inhibitor ZD4190.

PURPOSE: We evaluated noninvasive positron emission tomography (PET) imaging for monitoring tumor response to the VEGFR-2 tyrosine kinase (TK) inhibitor ZD4190 during cancer therapy. EXPERIMENTAL DESIGN: Orthotopic MDA-MB-435 tumor-bearing mice were treated with ZD4190 (100 mg/kg orally per day for three consecutive days). Tumor growth was monitored by caliper measurement. During the therapeutic period, longitudinal PET scans were acquired using (18)F-FDG, (18)F-FLT and (18)F-FPPRGD2 as imaging tracers to evaluate tumor glucose metabolism, tumor cell proliferation, and angiogenesis, respectively. Imaging metrics were validated by immunohistochemical analysis of Ki67, GLUT-1, F4/80, CD31, murine integrin ß3, and human integrin αvß3. RESULTS: Three consecutive daily oral administrations of 100 mg/kg of ZD4190 were effective in delaying MDA-MB-435 tumor growth. A significant difference in tumor volume was observed on day 7 between the treatment group and the control group (p < 0.01). After the final treatment, tumor growth resumed after a short delay. In the control tumors, (18)F-FPPRGD2 uptake was stable between days 0 and 7. In ZD4190-treated tumors, (18)F-FPPRGD2 uptake had decreased significantly relative to baseline by 26.74 ± 8.12% (p < 0.05) on day 1 and by 41.19 ± 6.63% (p < 0.01) on day 3, then had returned to baseline on day 7. Tumor uptake of (18)F-FLT had also decreased on both day 1 and day 3 after initiation of ZD4190 treatment. No significant change in (18)F-FDG uptake in ZD4190-treated tumors was observed, however, compared with the control group. All of the imaging findings were supported by ex vivo analysis of related biomarkers. CONCLUSION: The longitudinal imaging results demonstrated the usefulness of quantitative (18)F-FLT and (18)F-FPPRGD2 PET imaging in evaluating the early antiproliferative and antiangiogenic effects of ZD4190. The quantification data from the PET imaging were consistent with the pattern of initial growth inhibition with treatment, followed by tumor relapse after treatment cessation.

LC/MS evaluation of metabolism and membrane transport of bombesin peptides.

Two bombsin peptides, GRPR agonist [Aca-QWAVGHLM-NH(2)] and antagonist [fQWAVGHL-NHEthyl] were evaluated. We employed the highly sensitive Waters Q-Tof Premier MS coupled with a UPLC system to identify the metabolites produced by rat hepatocytes or PC-3 human prostate cancer cells; and we utilized the AB/MDS 4000 Q-Trap LC/MS/MS system with highly sensitive quantitative and qualitative performance, to quantitatively analyze the internalization of GRPR agonist and antagonist in PC-3 cells. The major metabolites of both GRPR agonist and antagonist were the result of peptide bond hydrolysis between W and A which was demonstrated by observation of the N-terminal fragment m/z 446 (Aca-QW-OH) for agonist and m/z 480 (fQW-OH) for antagonist. Both peptides were also hydrolyzed between A and V which formed peaks m/z 517 [Aca-QWA-OH] and m/z 555 (VGHLM-NH2) for the agonist and m/z 551 [fQWA-OH] and m/z 452 (VGHL-NHEthyl) for the antagonist. The peptide agonist also formed a unique metabolite that resulted from hydrolysis of the C-terminal amide. The antagonist showed significantly slower metabolism as compared to the agonist in both rat hepatocytes and PC-3 cells. The antagonist also showed significantly lower PC-3 cell internalization rate than that of the agonist. In conclusion, the metabolism profiles of both GRPR agonist and antagonist peptides were identified by LC/MS. The antagonist peptide was more stable than the agonist peptide in rat hepatocyte incubation. One major factor could be the hydrolysis-resistant C-terminal L-NHEthyl group compared with the unsubstituted amide of the agonist. Another factor could be different amino acid sequences of the agonist and antagonist that may also influence the enzymatic hydrolysis. The antagonist ligand is potentially more useful for receptor-targeted imaging due primarily to its higher metabolic stability.

Multiplexed PET probes for imaging breast cancer early response to VEGF121/rGel treatment.

In this study, we applied multiplexed positron emission tomography (PET) probes to monitor glucose metabolism, cellular proliferation, tumor hypoxia and angiogenesis during VEGF121/rGel therapy of breast cancer. Two doses of 12 mg/kg VEGF121/rGel, administered intraperitoneally, resulted in initial delay of tumor growth, but the growth resumed 4 days after tumor treatment was stopped. The average tumor growth rate expressed as V/V(0), were 1.11 ± 0.07, 1.21 ± 0.10, 1.58 ± 0.36 and 2.64 ± 0.72 at days 1, 3, 7 and 14, respectively. Meanwhile, the VEGF121/rGel treatment group showed V/V0 ratios of 1.04 ± 0.06, 1.05 ± 0.11, 1.09 ± 0.17 and 1.86 ± 0.36 at days 1, 3, 7 and 14, respectively. VEGF121/rGel treatment led to significantly decreased uptake of ¹8F-FPPRGD2 at day 1 (24.0 ± 8.8%, p < 0.05) and day 3 (36.3 ± 9.2%, p < 0.01), relative to the baseline, which slowly recovered to the baseline at day 14. ¹8F-FMISO uptake was increased in the treated tumors at day 1 (23.9 ± 15.7%, p < 0.05) and day 3 (51.4 ± 29.4%, p < 0.01), as compared to the control group. At days 7 and 14, ¹8F-FMISO uptake restored to the baseline level. The relative reductions in FLT uptake in treated tumors were approximately 13.0 ± 4.5% at day 1 and 25.0 ± 4.4% (p < 0.01) at day 3. No significant change of ¹8F-FDG uptake was observed in VEGF121/rGel treated tumors, compared with the control group. The imaging findings were supported by ex vivo analysis of related biomarkers. Overall, longitudinal imaging studies with 4 PET tracers demonstrated the feasibility and usefulness of multiplexed probes for quantitative measurement of antitumor effects of VEGF121/rGel at the early stage of treatment. This preclinical study should be helpful in accelerating anticancer drug development and promoting the clinical translation of molecular imaging.

PET of insulinoma using ¹8F-FBEM-EM3106B, a new GLP-1 analogue.

Derived from endocrine pancreatic beta cells, insulinomas express glucagon-like peptide-1 (GLP-1) receptor with high density and incidence. In this study, we labeled a novel GLP-1 analogue, EM3106B, with (18)F and performed PET imaging to visualize insulinoma tumors in an animal model. A GLP-1 analogue that contains multiple lactam bridges, EM3106B, was labeled with (18)F through a maleimide-based prosthetic group, N-2-(4-(18)F-fluorobenzamido)ethylmaleimide ((18)F-FBEM). The newly developed radiotracer was characterized by cell based receptor-binding assay, cell uptake and efflux assay. The stability in serum was evaluated by radio-HPLC analysis. In vivo PET imaging was performed in nude mice bearing subcutaneous INS-1 insulinoma tumors and MDA-MB-435 tumors of melanoma origin. Ex vivo biodistribution study was performed to confirm the PET imaging data. EM3106B showed high binding affinity (IC(50) = 1.38 nM) and high cell uptake (5.25 ± 0.61% after 120 min incubation). (18)F-FBEM conjugation of EM3106B resulted in high labeling yield (24.9 ± 2.4%) and high specific activity (>75 GBq/µmol at the end of bombardment). EM3106B specifically bound and was internalized by GLP-1R positive INS-1 cells. After intravenous injection of 3.7 MBq (100 µCi) of (18)F-FBEM-EM3106B, the INS-1 tumors were clearly visible with high contrast in relation to the contralateral background on PET images, and tumor uptake of (18)F-FBEM-EM3106B was determined to be 28.5 ± 4.7 and 25.4 ± 4.1% ID/g at 60 and 120 min, respectively. (18)F-FBEM-EM3106B showed low uptake in MB-MDA-435 tumors with low level of GLP-1R expression. Direct tissue sampling biodistribution experiment confirmed high tracer uptake in INS-1 tumors and receptor specificity in both INS-1 tumor and pancreas. In conclusion, (18)F-FBEM-EM3106B exhibited GLP-1R-receptor-specific targeting properties in insulinomas. The favorable characteristics of (18)F-FBEM-EM3106B, such as high specific activity and high tumor uptake, and high tumor to nontarget uptake, demonstrate that it is a promising tracer for clinical insulinoma imaging.

HSA coated iron oxide nanoparticles as drug delivery vehicles for cancer therapy.

An ongoing effort in the field of nanomedicine is to develop nanoplatforms with both imaging and therapeutic functions, the "nanotheranostics". We have previously developed a human serum albumin (HSA) coated iron oxide nanoparticle (HINP) formula and used multiple imaging modalities to validate its tumor targeting attributes. In the current study, we sought to impart doxorubicin (Dox) onto the HINPs and to assess the potential of the conjugates as theranostic agents. In a typical preparation, we found that about 0.5 mg of Dox and 1 mg of iron oxide nanoparticles (IONPs, Fe content) could be loaded into 10 mg of HSA matrices. The resulting D-HINPs (Dox loaded HINPs) have a hydrodynamic size of 50 nm and are able to release Dox in a sustained fashion. More impressively, the HINPs can assist the translocation of Dox across the cell membrane and even its accumulation in the nucleus. In vivo, D-HINPs retained a tumor targeting capability of HINPs, as manifested by both in vivo MRI and ex vivo immunostaining results. In a follow-up therapeutic study on a 4T1 murine breast cancer xenograft model, D-HINPs showed a striking tumor suppression effect that was comparable to that of Doxil and greatly outperformed free Dox. Such a strategy can be readily extended to load other types of small molecules, making HINP a promising theranostic nanoplatform.

High Glucose Attenuates Cardioprotective Effects of Glucagon-Like Peptide-1 Through Induction of Mitochondria Dysfunction via Inhibition of ß-Arrestin-Signaling.

An increased vulnerability has been detected after ischemia/reperfusion injury in cardiomyocytes in diabetic patients. Glucagon-like peptide-1 (GLP-1) has been proven to have a notable cardioprotective effect in cardiomyocytes. However, in diabetic patients, the cardioprotective effects of GLP-1 are compromised, which is called GLP-1 resistance. ß-arrestin is one of the two main downstream effectors of GLP-1 and ß-arrestin signaling pathway exerts cardioprotective effects upon activation of GLP-1R. Our hypothesis is that the increased vulnerability of cardiomyocytes in diabetic patients is partly due to disruption of the ß-arrestin signaling pathway. To test this, we analyzed cardiomyocyte viability and survival in high glucose and normal glucose condition after hypoxia/reoxygenation injury in vitro, additional GLP-1 was used to determine whether ß-arrestin signaling pathway was involved. We also investigated the role of mitochondrial dysfunction in GLP-1 resistance. Our results showed that cardioprotective effects of GLP-1 were reduced in high glucose cultured H9C2 cells compared to normal glucose cultured H9C2, verifying the existence of GLP-1 resistance in high glucose cultured H9C2 cells. Further study suggested that ß-arrestin plays a key role in GLP-1 resistance: ß-arrestin expression is notably downregulated in high glucose condition and cardioprotective effects of GLP-1 can be diminished by downregulation of ß-arrestin in normal glucose condition while upregulation of ß-arrestin can restore cardioprotective effects of GLP-1 in high glucose condition. Then we explore how ß-arrestin affects the cardioprotective effects of GLP-1 and found that ß-arrestin exerts cardioprotective effects by improving mitochondria quality control via the PI3K/Akt signaling pathway. Thus, our study found out a new mechanism of GLP-1 resistance of cardiomyocytes in high glucose conditions that impaired ß-arrestin expression, caused mitochondria dysfunction and eventually cell death. Our study provided a new perspective in treating myocardial ischemia/reperfusion injury in diabetic patients.

Postprocedure administration of insulin in canine autologous vein grafting: a potential strategy to attenuate intimal hyperplasia.

Intimal hyperplasia (IH) exerts a critical role in vein graft failure after arterial bypassing. Insulin has been demonstrated to remarkably decrease IH in the rat carotid injury model. We hypothesized that postoperative insulin medication prevents the autologous vein graft from IH. Dogs were subjected to jugular-carotid interposition bypass grafting and intravenously infused with vehicle, glucose-insulin-potassium, glucose-potassium, or glucose-insulin-potassium plus Wortmannin 5 minutes before and 4 hours after reperfusion. Then vein grafts were harvested for caspase-3 activation, cell apoptosis, phosphorylated Akt, and endothelial nitric oxide synthase level assays. Other dogs undergoing the same operation were administered with subcutaneous injection of 4 U insulin or 0.5 mL saline two times per day for 1 month postoperatively. Vein grafts were sampled to assess cell proliferation, intimal/medial thickness, and expression of endothelial nitric oxide synthase and [alpha]-smooth muscle actin. Glucose-potassium aggravated apoptosis and caspase-3 activation and decreased Akt and endothelial nitric oxide synthase phosphorylation; however, glucose-insulin-potassium significantly inhibited cell apoptosis and caspase-3 activation and increased phosphorylated Akt and pendothelial nitric oxide synthase levels in canine vein grafts. Wortmannin largely abolished the glucose-insulin-potassium-elicited effects. Moreover, postoperative insulin use greatly inhibited cell proliferation, reduced intimal/medial thickness, upregulated endothelial nitric oxide synthase, and [alpha]-smooth muscle actin expression. Insulin protects autologous vein grafts possibly through the phosphatidylinositol-3 kinase/Akt signaling pathway and prevents IH in autologous vein grafts.