Stability testing of iomeprol and iopamidol formulations subjected to X-ray radiation

INTRODUCTION

Exposure of iodinated contrast media (ICM) to X-rays is not uncommon, as contrast media are often stored in close proximity to radiological equipment. However, the interaction between X-rays and ICM is not widely investigated in literature. The present study aims to investigate the chemical stability of iomeprol and iopamidol, two commercial iodinated ICM commonly used in diagnostic imaging, under X-rays exposure.

METHODS

Different formulations of iopamidol and iomeprol (iodine concentration 9 to 400 mgI/mL, volume 50-500 mL) were exposed to three different conditions of X-ray irradiation: i) 1 month storage in CT room (≈5-15 mGy); (ii) low-dose protocol (≈10 mGy); (ii) stressed protocol (≈100 mGy). Unexposed and exposed solutions were characterized by high-performance liquid chromatography in terms of concentration of active pharmaceutical ingredient (API), iodine species and by products. In addition, appearance and colour of the solutions were inspected and pH measured.

RESULTS

API concentrations, appearance, colour and pH of the exposed formulations remained unaffected by X-rays. Measured concentrations of iodine species and by products were observed well within the acceptability criteria, i.e. values turned out to be lower than specifications limits established by the manufacturer, considering both release and shelf-life values.

CONCLUSIONS

Up to 100 mGy X-ray exposure did not induce any alteration of iomeprol and iopamidol formulation, nor a detectable increase in the concentration of iodine species or by-products.

IMPLICATIONS FOR PRACTICE

Our study strengthens the hypothesis that ICM are stable under X-rays exposure up to 100 mGy.

Left atrial function after standalone totally thoracoscopic left atrial appendage exclusion in atrial fibrillation patients with absolute contraindication to oral anticoagulation therapy

Background

Left atrial appendage (LAA) is a common source of thrombi in patients with atrial fibrillation (AF). The effect on left atrial (LA) function of the Totally Thoracoscopic (TT)-LAA exclusion with epicardial clip is currently unknown. This study aims at evaluating the effect of TT-LAA exclusion on LA function.

Methods

Standalone TT-LAA exclusion with the clip device was performed in 26 patients with AF and contraindication to oral anticoagulation (OAC). A 3D CT scan, trans-esophageal echocardiography, spirometry and cerebrovascular doppler ultrasound were performed preoperatively. Clip positioning and LAA exclusion were guided and confirmed by intraoperative trans-esophageal echo. To evaluate LA function, standard transthoracic echocardiography and 2D strain of LA were performed before surgery, at discharge and at 3-month follow-up.

Results

The mean CHA2DS2-VASc and HASBLED scores were 4.6 and 2.4 respectively. There were no major complications during the procedure. At median follow-up of 10.3 months, 1 (3.8%) non-cardiovascular death, 1 (3.8%) stroke and 4 (15.4%) cardiovascular hospitalizations occurred. At 2D strain of LA, the reservoir function decreased significantly at discharge, compared to baseline and recovered at 3-months follow-up. Furthermore, NT-proBNP increased significantly after the procedure with a return to baseline after 3 months. Changes in E/A were persistent at 3 months.

Conclusion

Our data in a small cohort suggest that TT-LAA exclusion with epicardial clip can be a safe procedure with regards to the atrial function. The LAA amputation impairs the reservoir LA function on the short term, that recovers over time.

Left atrial function after standalone totally thoracoscopic left atrial appendage exclusion in af patients with absolute contraindication to oral anticoagulation therapy

Funding Acknowledgements

Type of funding sources: None.

Introduction

Left atrial appendage (LAA) is the source of more than 90% of thrombi in patients with atrial fibrillation (AF).  The Totally Thoracoscopic (TT) LAA exclusion with epicardial clip has become a safe and effective procedure, but the effect on left atrial (LA) function remains unknown.

Purpose

The aim of this study was to assess the effect of TT LAA exclusion on LA function.

Methods

20 patients (15 males) with non-valvular AF and contraindication to oral anticoagulation therapy (OAT) or antiplatelet therapy underwent standalone TT LAA exclusion with the Atriclip Pro II device. All patients were screened preoperatively with 3D CT scan, trans-esophageal echocardiography, spirometry and cerebrovascular doppler ultrasound. Intraoperative Atriclip Pro II positioning and LAA exclusion were guided and confirmed by trans-esophageal echo. To objectify LA function, transthoracic echocardiography with 2D Speckle tracking was performed before surgery, at discharge and at 3-month follow-up. All patients were not on anticoagulation nor antiplatelet therapy at the time of surgery, at discharge and at control visit.

Results

Baseline characteristics are reported in Table I. There were no major complications during the procedures. One non cardiovascular death, one minor stroke and 4 hospitalizations occur at 1-year follow up. The reservoir LA function considering the strain measurements dramatically decreased few days after the procedure and it recovered at 3-month follow-up compared to baseline, even though the LA volume is augmented (Table II). Furthermore, NT pro-BNP increased and ventricular strain decreased significantly after the procedure recovering over time.

Conclusion

TT LAA exclusion with Atriclip Pro II device is a safe and effective procedure in preventing AF related stroke in patients with contraindication to OAT. Our findings suggest that the LAA epicardial clip impairs immediately the reservoir LA function that recovers over time. Abstract Table I  Abstract Table II

[Risk assessment and early predictors of survival after out-of-hospital cardiac arrest in the province of Trento, Italy]

BACKGROUND

Early prognostication of patients experiencing out-of-hospital cardiac arrest (OHCA) remains difficult, with no recommended risk assessment tool. The aim of this study was to determine and assess the association between available variables with survival at discharge of patients with OHCA in our regional reality.

METHODS

We conducted a retrospective observational study in a single-center cohort of 236 consecutive patients with OHCA and return of spontaneous circulation admitted to the S. Chiara Hospital (Trento, Italy) from 2012 to 2015. We applied a backward stepwise multivariable logistic regression performed on 26 variables significantly related to outcome to identify predictors. The final model was evaluated for discrimination with area under the curve (AUC) of a receiver operating characteristic curve and for calibration with Hosmer-Lemeshow test and with calibration belt.

RESULTS

We identified four independent factors predictive of outcome: age, arterial blood pH, coronary angiography execution and intervention of helicopter. The final model presented good discrimination with an average AUC of 0.78 (95% confidence interval 0.72-0.84) and was well calibrated, as confirmed by the Hosmer-Lemeshow test (p=0.45) and the calibration belt plot (p=0.597).

CONCLUSIONS

Age, arterial blood pH, coronary angiography execution and intervention of helicopter were variables predictive of outcome. Identified predictors are in agreement with the literature and relate to local reality. Accurate prognostic assessment would facilitate an earlier identification of patients who may benefit from intensive advanced post-resuscitation care.

Nuclear magnetic resonance studies of DNP-ready trehalose obtained by solid state mechanochemical amorphization

(1)H nuclear spin-lattice relaxation and Dynamic Nuclear Polarization (DNP) have been studied in amorphous samples of trehalose sugar doped with TEMPO radicals by means of mechanical milling, in the 1.6-4.2 K temperature range. The radical concentration was varied between 0.34 and 0.81%. The highest polarization of 15% at 1.6 K, observed in the sample with concentration 0.50%, is of the same order of magnitude of that reported in standard frozen solutions with TEMPO. The temperature and concentration dependence of the spin-lattice relaxation rate 1/T1, dominated by the coupling with the electron spins, were found to follow power laws with an exponent close to 3 in all samples. The observed proportionality between 1/T1 and the polarization rate 1/Tpol, with a coefficient related to the electron polarization, is consistent with the presence of Thermal Mixing (TM) and a good contact between the nuclear and the electron spins. At high electron concentration additional relaxation channels causing a decrease in the nuclear polarization must be considered. These results provide further support for a more extensive use of amorphous DNP-ready samples, obtained by means of comilling, in dissolution DNP experiments and possibly for in vivo metabolic imaging.

Traumatic avulsion of the tricuspid valve after gas bottle explosion

We present a very rare example of chronic right heart failure caused by torrent tricuspid regurgitation. Massive right heart dilatation and severe tricuspid regurgitation due to avulsion of the tricuspid valve apparatus occurred as a result of a blunt chest trauma following the explosion of a gas bottle 20 years before admission, when the patient was a young man in Vietnam. After this incident, the patient went through a phase of severe illness, which can retrospectively be identified as an acute right heart decompensation with malaise, ankle edema, and dyspnea. Blunt chest trauma caused by explosives leading to valvular dysfunction has not been reported in the literature so far. It is remarkable that the patient not only survived this trauma, but had been managing his chronic heart failure well without medication for over 20 years.

The role of the glassy dynamics and thermal mixing in the dynamic nuclear polarization and relaxation mechanisms of pyruvic acid

The temperature dependence of (1)H and (13)C nuclear spin-lattice relaxation rate 1/T1 has been studied in the 1.6-4.2 K temperature range in pure pyruvic acid and in pyruvic acid containing trityl radicals at a concentration of 15 mM. The temperature dependence of 1/T1 is found to follow a quadratic power law for both nuclei in the two samples. Remarkably the same temperature dependence is displayed also by the electron spin-lattice relaxation rate 1/T1e in the sample containing radicals. These results are explained by considering the effect of the structural dynamics on the relaxation rates in pyruvic acid. Dynamic nuclear polarization experiments show that below 4 K the (13)C build up rate scales with 1/T1e, in analogy to (13)C 1/T1 and consistently with a thermal mixing scenario where all the electrons are collectively involved in the dynamic nuclear polarization process and the nuclear spin reservoir is in good thermal contact with the electron spin system.

Dynamic nuclear polarization of a glassy matrix prepared by solid state mechanochemical amorphization of crystalline substances

A mechanochemical "solvent-free" route is presented for the preparation of solid samples ready to be employed in the Dynamic Nuclear Polarization (DNP). (1)H-DNP build-up curves at 3.46 T as a function of temperature and radical concentration show steady state nuclear polarization of 10% (0.5% TEMPO concentration at 1.75 K).

In vivo and in vitro liver cancer metabolism observed with hyperpolarized [5-(13)C]glutamine

Glutamine metabolism is, with its many links to oncogene expression, considered a crucial step in cancer metabolism and it is thereby a key target for alteration in cancer development. In particular, strong correlations have been reported between oncogene expression and expression and activity of the enzyme glutaminase. This mitochondrial enzyme, which is responsible for the deamidation of glutamine to form glutamate, is overexpressed in many tumour tissues. In animal models, glutaminase expression is correlated with tumour growth rate and it is readily possible to limit tumour growth by suppression of glutaminase activity. In principle, hyperpolarized (13)C MR spectroscopy can provide insight to glutamine metabolism and should hence be a valuable tool to study changes in glutaminase activity as tumours progress. However, no such successful in vivo studies have been reported, even though several good biological models have been tested. This may, at least partly, be due to problems in preparing glutamine for hyperpolarization. This paper reports a new and improved preparation of hyperpolarized [5-(13)C]glutamine, which provides a highly sensitive (13)C MR marker. With this preparation of hyperpolarized [5-(13)C]glutamine, glutaminase activity in vivo in a rat liver tumour was investigated. Moreover, this marker was also used to measure response to drug treatment in vitro in cancer cells. These examples of [5-(13)C]glutamine used in tumour models warrant the new preparation to allow metabolic studies with this conditionally essential amino acid.

Improving the procedure for detection of intrahepatic transplanted islets by magnetic resonance imaging

Islet transplantation is an effective therapy for restoring normoglycemia in type-1 diabetes, but long-term islet graft function is achieved only in a minority of cases. Noninvasive magnetic resonance imaging of pancreatic islets is an attractive option for "real-time" monitoring of graft evolution. So far, previous studies have been performed in the absence of a standardized labeling procedure and, besides a feasibility study in patients, the effectiveness and safety of various labeling approaches were tested only with high field magnets (4.7 T). In this study, we addressed: (a) standardization of a labeling procedure for human islets with clinically-approved contrast agent Endorem, (b) safety aspects of labeling related to inflammation and (c) quality of imaging both at 7 T and 1.5 T. We have highlighted that the ratio of Endorem/islet is crucial for reproducible labeling, with a ratio of 2.24 ug/IEQ, allowing successful in vivo imaging both with 1.5 T and 7.0 T magnets up to 143 days after intrahepatic transplant. With this standardized labeling procedure, labeled islets are neither inflamed nor more susceptible to inflammatory insults than unlabeled ones. This report represents an important contribution towards the development of a standardized and safe clinical protocol for the noninvasive imaging of transplanted islets in humans.