Strain Differences Determine the Suitability of Animal Models for Noninvasive <Emphasis Type="Italic">In Vivo</Emphasis> Beta Cell Mass Determination with Radiolabeled Exendin

Purpose

Noninvasive beta cell mass (BCM) quantification is a crucial tool to understand diabetes development and progression. [¹¹¹In]exendin is a promising agent for in vivo beta cell imaging, but tracer testing has been hampered by the lack of well-defined rodent models.

Procedures

Biodistribution and pancreatic uptake of [¹¹¹In]exendin were compared in rats and mice. In selected models, the amount of [¹¹¹In]exendin accumulation in the pancreas and other organs was determined using a model of alloxan-induced beta cell loss. GLP-1R expression levels were analyzed by RT-PCR and immunohistochemistry.

Results

Namely Brown Norway rats showed beta-cell-specific tracer accumulation and favorable pancreas-to-background ratios for noninvasive BCM determination. Mice displayed receptor-mediated [¹¹¹In]exendin uptake in endocrine and exocrine pancreas, in spite of very low GLP-1R expression in exocrine tissue.

Conclusions

Rats display better characteristics for in vivo BCM determination than mice and are suggested as a more adequate model for humans.

     

Prone equals prone? Impact of positioning techniques on respiratory function in anesthetized and paralyzed healthy children

Objectives

Although the prone position is effectively used to improve oxygenation, its impact on functional residual capacity is controversial. Different techniques of body positioning might be an important confounding factor. The aim of this study was to determine the impact of two different prone positioning techniques on functional residual capacity and ventilation distribution in anesthetized, preschool-aged children.

Design

Functional residual capacity and lung clearance index, a measure of ventilation homogeneity, were calculated using a sulfur-hexafluoride multibreath washout technique. After intubation, measurements were taken in the supine position and, in random order, in the flat prone position and the augmented prone position (gel pads supporting the pelvis and the upper thorax).

Setting

Pediatric anesthesia unit of university hospital.

Patients and participants

Thirty preschool children without cardiopulmonary disease undergoing elective surgery.

Measurements and results

Mean (range) age was 48.5 (24–80) months, weight 17.2 (10.5–26.9)?kg, functional residual capacity (mean ±?SD) 22.9?±?6.2?ml.kg ^?1 in the supine position and 23.3?±?5.6?ml.kg ^?1 in the flat prone position, while lung clearance indices were 8.1?±?2.3 vs. 7.9?±?2.3, respectively. In contrast, functional residual capacity increased to 27.6 ± 6.5 ml.kg ^?1 (pp

Conclusions

Functional residual capacity and ventilation distribution were similar in the supine and flat prone positions, while these parameters improved significantly in the augmented prone position, suggesting that the technique of prone positioning has major implications for pulmonary function.

     

Distribution of lung ventilation in spontaneously breathing neonates lying in different body positions

Objective

The aim of our study was to determine the effect of the irregular spontaneous breathing pattern and posture on the spatial distribution of ventilation in neonates free from respiratory disease by the non-invasive imaging method of electrical impedance tomography (EIT). Scanning of spontaneously breathing neonates is the prerequisite for later routine application of EIT in babies with lung pathology undergoing ventilator therapy.

Design

Prospective study.

Setting

Neonatal intensive care unit at a university hospital.

Patients

Twelve pre-term and term neonates (mean age: 23 days; mean body weight: 2,465 g; mean gestational age: 34 weeks; mean birth weight: 2,040 g).

Interventions

Change in body position in the sequence: supine, right lateral, prone, supine.

Measurements and results

EIT measurements were performed using the Göttingen GoeMF I system. EIT scans of regional lung ventilation showing the distribution of respired air in the chest cross-section were generated during phases of rapid tidal breathing and deep breaths. During tidal breathing, 54.5±8.3%, 55.2±10.5%, 59.9±8.4% and 54.2±8.5% of inspired air (mean values ± SD) were directed into the right lung in the supine, right lateral, prone and repeated supine postures respectively. During deep inspirations, the right lung ventilation accounted for 52.6±7.9%, 68.5±8.5%, 55.4±8.2% and 50.5±6.6% of total ventilation respectively.

Conclusion

The study identified the significant effect of breathing pattern and posture on the spatial distribution of lung ventilation in spontaneously breathing neonates. The results demonstrate that changes in regional ventilation can easily be determined by EIT and bode well for the future use of this method in paediatric intensive care.

     

Effect of synbiotic therapy on the incidence of ventilator associated pneumonia in critically ill patients: a randomised,double-blind,placebo-controlled trial

Objective

To investigate the effect of enteral Synbiotic 2000 FORTE^® (a mixture of lactic acid bacteria and fibre) on the incidence of ventilator associated pneumonia (VAP) in critically ill patients.

Design

Prospective, randomised, double blind, placebo controlled trial.

Setting

Tertiary referral centre, general Adult Intensive Care Unit (ICU).

Patients and participants

259 enterally fed patients requiring mechanical ventilation for 48 h or more were enrolled.

Intervention

All patients were enterally fed as per a standard protocol and randomly assigned to receive either synbiotic 2000 FORTE^® (twice a day) or a cellulose-based placebo for a maximum of 28 days.

Measurements and results

Treatment group (n = 130) was well matched with placebo group (n = 129) for age (mean 49.5 and 50 years, respectively) and APACHE II score (median 17 for both). Oropharyngeal microbial flora and colonisation rates were unaffected by synbiotics. The overall incidence of VAP was lower than anticipated (11.2%) and no statistical difference was demonstrated between groups receiving synbiotic and placebo in the incidence of VAP (9 and 13%, P = 0.42), VAP rate per 1,000 ventilator days (13 and 14.6, P = 0.91) or hospital mortality (27 and 33%, P = 0.39), respectively.

Conclusions

Enteral administration of Synbiotic 2000 FORTE^® has no statistically significant impact on the incidence of VAP in critically ill patients.

     

Explore the influence of BMI in the optimal time of weaning from sequential mechanical ventilation for severity chronic obstructive pulmonary disease

Objective

To study the clinical effect of body mass index (BMI) in the optimal time of weaning from sequential invasive-noninvasive mechanical ventilation (MV) by treating severity chronic obstructive pulmonary disease (COPD) patients.

Methods

94 patients with severity COPD were divided into the control group (BMI<21) and the study group (BMI>21). These two groups were treated by similar symptomatic therapies such as mechanical ventilation, antibacterial, antispasmodic, relieving asthma, antitussive, expectorant, correction of electrolyte imbalance and acid-base balance disorders, strengthen nutritional support, etc.

Results

Compared with the control group, the study group had shorter duration of invasive mechanical ventilation, non-invasive mechanical ventilation time, total mechanical ventilation time, total hospital stay (P<0.01). There are significant differences between these two groups in re-intubation rate, VAP occurred in the number of case, hospital mortality rate in 28 days (P<0.05).

Conclusions

It is difficult to wean successfully from sequential mechanical ventilation for severity COPD patients (BMI<21), so BMI as one of important reference index can be used to estimate the optimal time for weaning from sequential mechanical ventilation for severity COPD patients.

     

Olanzapine vs haloperidol: treating delirium in a critical care setting

Objective

To compare the safety and estimate the response profile of olanzapine, a second-generation antipsychotic, to haloperidol in the treatment of delirium in the critical care setting.

Design

Prospective randomized trial

Setting

Tertiary care university affiliated critical care unit.

Patients

All admissions to a medical and surgical intensive care unit with a diagnosis of delirium.

Interventions

Patients were randomized to receive either enteral olanzapine or haloperidol.

Measurements

Patient’s delirium severity and benzodiazepine use were monitored over 5 days after the diagnosis of delirium.

Main results

Delirium Index decreased over time in both groups, as did the administered dose of benzodiazepines. Clinical improvement was similar in both treatment arms. No side effects were noted in the olanzapine group, whereas the use of haloperidol was associated with extrapyramidal side effects.

Conclusions

Olanzapine is a safe alternative to haloperidol in delirious critical care patients, and may be of particular interest in patients in whom haloperidol is contraindicated.

     

Regional lung derecruitment after endotracheal suction during volume- or pressure-controlled ventilation: a study using electric impedance tomography

Objective

To assess lung volume and compliance changes during open- and closed-system suctioning using electric impedance tomography (EIT) during volume- or pressure-controlled ventilation.

Design and setting

Experimental study in a university research laboratory.

Subjects

Nine bronchoalveolar saline-lavaged pigs.

Interventions

Open and closed suctioning using a 14-F catheter in volume- or pressure-controlled ventilation at tidal volume 10?ml/kg, respiratory rate 20?breaths/min, and positive end-expiratory pressure 10?cmH₂O.

Measurements and results

Lung volume was monitored by EIT and a modified N₂ washout/-in technique. Airway pressure was measured via a pressure line in the endotracheal tube. In four ventral-to-dorsal regions of interest regional ventilation and compliance were calculated at baseline and 30?s and 1, 2, and 10?min after suctioning. Blood gases were followed. At disconnection functional residual capacity (FRC) decreased by 58?±?24% of baseline and by a further 22?±?10% during open suctioning. Arterial oxygen tension decreased to 59?±?14% of baseline value 1?min after open suctioning. Regional compliance deteriorated most in the dorsal parts of the lung. Restitution of lung volume and compliance was significantly slower during pressure-controlled than volume-controlled ventilation.

Conclusions

EIT can be used to monitor rapid lung volume changes. The two dorsal regions of the lavaged lungs are most affected by disconnection and suctioning with marked decreases in compliance. Volume-controlled ventilation can be used to rapidly restitute lung aeration and oxygenation after lung collapse induced by open suctioning.

     

Nasal continuous positive airway pressure decreases respiratory muscles overload in young infants with severe acute viral bronchiolitis

Objective

To determine the efficacy of nasal continuous positive airway pressure (nCPAP) on respiratory distress symptoms and respiratory effort in young infants with acute respiratory syncytial virus bronchiolitis.

Design

Prospective study.

Setting

The paediatric intensive care unit of a university hospital.

Patients

Twelve infants less than 3 months of age, with severe respiratory distress.

Interventions

Respiratory distress was quantified with a specific scoring system. Oesophageal pressure (Pes) was measured during spontaneous ventilation before and after nCPAP, delivered through an infant-adapted ventilator. Simultaneous recording of gastric pressure (Pgas) was performed in the five oldest patients.

Measurements and results

The respiratory distress score decreased after nCPAP, particularly accessory muscles’ use and expiratory wheezing. The breathing pattern was modified, with shorter inspiratory and longer expiratory time. Pes swings and PTPes_insp, two indices of inspiratory effort, were reduced by 54 (±4)% and 59 (±5)%. PTPgas_exp, an indicator of expiratory muscles activity, was completely abolished. A significant correlation was observed between the respiratory distress score and Pes swings at baseline and after nCPAP.

Conclusions

In young infants with severe acute respiratory syncytial virus bronchiolitis, nCPAP rapidly unloads respiratory muscles and improves respiratory distress symptoms.

     

Low dose quetiapine induced galactorrhoea: a case report

Background

Quetiapine causes less prolactin elevation and/or galactorrhoea than other atypical antipsychotics.

Case Presentation

Ms AB had galactorrhoea and raised prolactin levels at only 100 mg of quetiapine daily.

Conclusion

Low dose quetiapine can also cause galactorrhoea.

     

Esophageal and transpulmonary pressure in the clinical setting: meaning,usefulness and perspectives

Purpose

Esophageal pressure (Pes) is a minimally invasive advanced respiratory monitoring method with the potential to guide management of ventilation support and enhance specific diagnoses in acute respiratory failure patients. To date, the use of Pes in the clinical setting is limited, and it is often seen as a research tool only.

Methods

This is a review of the relevant technical, physiological and clinical details that support the clinical utility of Pes.

Results

After appropriately positioning of the esophageal balloon, Pes monitoring allows titration of controlled and assisted mechanical ventilation to achieve personalized protective settings and the desired level of patient effort from the acute phase through to weaning. Moreover, Pes monitoring permits accurate measurement of transmural vascular pressure and intrinsic positive end-expiratory pressure and facilitates detection of patient–ventilator asynchrony, thereby supporting specific diagnoses and interventions. Finally, some Pes-derived measures may also be obtained by monitoring electrical activity of the diaphragm.

Conclusions

Pes monitoring provides unique bedside measures for a better understanding of the pathophysiology of acute respiratory failure patients. Including Pes monitoring in the intensivist’s clinical armamentarium may enhance treatment to improve clinical outcomes.

     

The intra-conduit release method is useful for avoiding migration of metallic stents during EUS-guided hepaticogastrostomy (with video)

Purpose

Although EUS-guided hepaticogastrostomy (EUS-HGS) with a covered self-expandable metal stent (SEMS) is a useful procedure, it is associated with severe adverse events, including stent migration. We, therefore, developed an intra-conduit release method, and investigated whether the technique yields a safer and more stable procedure.

Methods

The intra-conduit release method is a procedure to release the SEMS in the working channel conduit of the scope for anchoring between the liver and stomach to avoid stent migration. Forty-three patients who underwent EUS-HGS at two high-volume centers in Japan were enrolled in this retrospective study, and the safety and usefulness of this method were evaluated retrospectively.

Results

The intra-conduit release method was applied in 36 cases. The technical success rate of EUS-HGS with the intra-conduit release method was significantly higher in comparison with the conventional method. Additionally, the rate of early adverse events was significantly lower than that for the conventional method.

Conclusion

The intra-conduit release method during EUS-HGS is useful for a stable procedure that avoids early adverse events.

     

Automatic adjustment of pressure support by a computer-driven knowledge-based system during noninvasive ventilation: a feasibility study

Objective

To evaluate the feasibility of using a knowledge-based system designed to automatically titrate pressure support (PS) to maintain the patient in a “respiratory comfort zone” during noninvasive ventilation (NIV) in patients with acute respiratory failure.

Design and setting

Prospective crossover interventional study in an intensive care unit of a university hospital.

Patients

Twenty patients.

Interventions

After initial NIV setting and startup in conventional PS by the chest physiotherapist NIV was continued for 45?min with the automated PS activated.

Measurements and results

During automated PS minute-volume was maintained constant while respiratory rate decreased significantly from its pre-NIV value (20?±?3 vs. 25?±?3?bpm). There was a trend towards a progressive lowering of dyspnea. In hypercapnic patients PaCO₂ decreased significantly from 61?±?9 to 51?±?2?mmHg, and pH increased significantly from 7.31?±?0.05 to 7.35?±?0.03. Automated PS was well tolerated. Two system malfunctions occurred prompting physiotherapist intervention.

Conclusions

The results of this feasibility study suggest that the system can be used during NIV in patients with acute respiratory failure. Further studies should now determine whether it can improve patient-ventilator interaction and reduce caregiver workload.

     

Création d’un programme d’éducation thérapeutique en douleur chronique (PETDC) — Expérience Canadienne

Aims

Create an educational program in chronic pain (EPCP).

Material and methods

We used a four-step process to create the EPCP tailored to patient’s needs.

Results

Five groups of patients can benefit from the program annually. Based on their own assessment, patients stated that their knowledge of chronic pain improved between 2.8 to 24%. The satisfaction with the EPCP was 8.67/10.

Conclusion

Our EPCP helps patients gain and maintain the skills they need to best manage their lives with a chronic pain.

     

Imaging of Claudin-4 in Pancreatic Ductal Adenocarcinoma Using a Radiolabelled Anti-Claudin-4 Monoclonal Antibody

Purpose

Despite its widespread use, the positron emission tomography (PET) radiotracer 2-deoxy-2-[¹⁸F]fluoro-D-glucose ([¹⁸F]FDG) has been shown in clinical settings to be ineffective for improving early diagnosis of pancreatic ductal adenocarcinoma (PDAC). A promising biomarker for PDAC detection is the tight junction protein claudin-4. The purpose of this study was to evaluate a new single-photon emission computed tomography (SPECT) imaging agent, [¹¹¹In]anti-claudin-4 mAb, with regard to its ability to allow visualisation of claudin-4 in a xenograft and a genetically engineered mouse model of PDAC.

Procedures

The ability of [¹¹¹In]anti-claudin-4 mAb to selectively target claudin-4 was assessed using two human xenograft tumour models with differential claudin-4 status in mice. [¹¹¹In]anti-claudin-4 mAb was also used to detect PDAC development in genetically engineered KPC mice. The PDAC status of these mice was confirmed with [¹⁸F]FDG-PET, magnetic resonance imaging (MRI), histology, and immunofluorescence microscopy.

Results

High uptake of [¹¹¹In]anti-claudin-4 mAb was observed in PDAC xenografts in mice, reaching 16.9 ± 4.5 % of injected dose per gram (% ID/g) at 72 h post-injection. This uptake was mediated specifically by the expression of claudin-4. Uptake of [¹¹¹In]anti-claudin-4 mAb also enabled clear visualisation of spontaneous PDAC formation in KPC mice.

Conclusions

[¹¹¹In]anti-claudin-4 mAb allows non-invasive detection of claudin-4 upregulation during development of PDAC and could potentially be used to aid in the early detection and characterisation of this malignancy.

     

Quantifying unintended exposure to high tidal volumes from breath stacking dyssynchrony in ARDS: the BREATHE criteria

Purpose

Breath stacking dyssynchrony generates higher tidal volumes than intended, potentially increasing lung injury risk in acute respiratory distress syndrome (ARDS). Lack of validated criteria to quantify breath stacking dyssynchrony contributes to its under-recognition. This study evaluates performance of novel, objective criteria for quantifying breath stacking dyssynchrony (BREATHE criteria) compared to existing definitions and tests if neuromuscular blockade eliminates high-volume breath stacking dyssynchrony in ARDS.

Methods

Airway flow and pressure were recorded continuously for up to 72 h in 33 patients with ARDS receiving volume-preset assist-control ventilation. The flow–time waveform was integrated to calculate tidal volume breath-by-breath. The BREATHE criteria considered five domains in evaluating for breath stacking dyssynchrony: ventilator cycling, interval expiratory volume, cumulative inspiratory volume, expiratory time, and inspiratory time.

Results

The observed tidal volume of BREATHE stacked breaths was 11.3 (9.7–13.3) mL/kg predicted body weight, significantly higher than the preset volume [6.3 (6.0–6.8) mL/kg; p < 0.001]. BREATHE identified more high-volume breaths (≥2 mL/kg above intended volume) than the other existing objective criteria for breath stacking [27 (7–59) vs 19 (5–46) breaths/h; p < 0.001]. Agreement between BREATHE and visual waveform inspection was high (raw agreement 96.4–98.1 %; phi 0.80–0.92). Breath stacking dyssynchrony was near-completely eliminated during neuromuscular blockade [0 (0–1) breaths/h; p < 0.001].

Conclusions

The BREATHE criteria provide an objective definition of breath stacking dyssynchrony emphasizing occult exposure to high tidal volumes. BREATHE identified high-volume breaths missed by other methods for quantifying this dyssynchrony. Neuromuscular blockade prevented breath stacking dyssynchrony, assuring provision of the intended lung-protective strategy.

     

Current and Emerging Treatment Modalities for Leber’s Hereditary Optic Neuropathy: A Review of the Literature

Introduction

The purpose of this review is to present the current and emerging treatment alternatives for Leber’s hereditary optic neuropathy (LHON), emphasizing the most recent use of idebenone and stem cells or gene therapy.

Methods

A comprehensive literature review was performed at the PubMed database regarding the various treatment modalities for LHON.

Results

Treatment modalities for LHON include nutritional supplements, activators of mitochondrial biogenesis, brimonidine, and symptomatic and supportive treatment, but nowadays attention is being paid to idebenone and gene therapy or stem cells.

Conclusion

The treatment of LHON remains challenging, given the nature of the disease and its prognosis.

     

Lack of agreement between thermodilution and electrical velocimetry cardiac output measurements

Objective

The modified algorithm for the non-invasive determination of cardiac output (CO) by electrical bioimpedance—electrical velocimetry (EV^®)—has been reported to give reliable results in comparison with echocardiography and pulmonary arterial thermodilution (PA-TD) in patients either before or after cardiac surgery. The present study was designed to determine whether EV^®-CO measurements reflect intraindividual changes in CO during cardiac surgery.

Design

Prospective, observational study.

Setting

Operating room (OR) and intensive care unit (ICU) of a university hospital.

Patients

Twenty-nine patients undergoing elective cardiac surgery.

Interventions

None.

Measurements

CO was determined simultaneously by PA-TD and EV^® after induction of anesthesia (t1) and 4.9?±?3.5?h after ICU admission (t2).

Results

TD-CO was 3.9?±?1.4 and 5.4?±?1.1 l/min at t1 and t2 (?p?®-CO was 4.3?±?1.1 and 4.9?±?1.5 l/min at t1 and t2 (?p?=?0.013). Bland–Altman analysis showed a bias of ?0.4 l/min and 0.4 l/min and a precision of 3.2 and 3.6 l/min (34.3% and 67.4%) at t1 and t2, respectively. Analysis of the individual pre- to postoperative changes in CO with both methods revealed bidirectional changes in n?=?12 patients and unidirectional changes with a difference greater than 50% and less than 50% in n?=?9 and n?=?8 patients, respectively.

Conclusions

The disagreement between PA-TD and EV^®-CO measurements after anesthesia induction and after ICU admission, as well as the fact that thoracic bioimpedance did not adequately reflect pre- to postoperative changes in CO, questions the reliability of EV^®-CO measurements in cardiac surgery patients and contrasts sharply with previous studies.

     

MAO-B Inhibitors Do Not Block <Emphasis Type="Italic">In Vivo</Emphasis> Flortaucipir([<Superscript>18</Superscript>F]-AV-1451) Binding

Purpose

Recent evidence suggests that the tau radiotracer [¹⁸F]THK-5351 displays high affinity for the monoamine oxidase type B (MAO-B) enzyme. Utilizing another tau-tracer, flortaucipir ([¹⁸F]AV-1451), we previously reported that non-demented Parkinson’s disease patients show off-target binding in subcortical structures, but no appreciable cortical uptake. However, 59 % of these patients were receiving MAO-B inhibitors at the time of their scan. Here, we retrospectively investigated if MAO-B inhibitors in clinical doses affect flortaucipir binding.

Procedures

We compared the standard uptake values of flortaucipir at regional and voxel levels in Parkinson’s disease patients who received MAO-B inhibitors with those who did not.

Results

Sixteen of 27 Parkinson’s disease patients received MAO-B inhibitors at the time of scan. We found no significant flortaucipir uptake differences between the groups at voxel or regional levels.

Conclusion

Use of MAO-B inhibitors at pharmaceutical levels did not significantly affect flortaucipir binding. Thus, MAO-B does not appear to be a significant binding target of flortaucipir.

     

SkQ1 Ophthalmic Solution for Dry Eye Treatment: Results of a Phase 2 Safety and Efficacy Clinical Study in the Environment and During Challenge in the Controlled Adverse Environment Model

Introduction

This Phase 2 clinical trial assessed the efficacy and safety of the novel antioxidative, renewable compound SkQ1 for topical treatment of dry eye signs and symptoms.

Methods

In a single-center, randomized, double-masked, placebo-controlled, 29-day study, 91 subjects with mild to moderate dry eye instilled the study drug twice daily and recorded dry eye symptoms daily. Subjects were randomized 1:1:1 into one of three ophthalmic solution treatment groups: SkQ1 1.55 µg/mL, SkQ1 0.155 µg/mL, or 0.0 µg/mL (placebo). Subjects were exposed to a controlled adverse environment chamber at 3 of the 4 study visits (Day ?7, Day 1, and Day 29). Investigator assessments occurred at all study visits.

Results

SkQ1 was safe and efficacious in treating dry eye signs and symptoms. Statistically significant improvements with SkQ1 compared to placebo occurred for the dry eye signs of corneal fluorescein staining and lissamine green staining in the central region and lid margin redness, and for the dry eye symptoms of ocular discomfort, dryness, and grittiness. In addition, SkQ1 demonstrated greater efficacy compared to placebo, although the differences were not statistically significant, for corneal fluorescein staining in other regions and/or time points (total staining score, central region, corneal sum score, and temporal region), lissamine green staining for the central and nasal regions, and blink rate scores.

Conclusions

This Phase 2 study indicated that SkQ1 is safe and efficacious for the treatment of dry eye signs and symptoms and supported previous study results.

Trial registration

Clinicaltrials.gov identifier: NCT02121301.

Funding

Miotech S.A.

     

Pre-clinical Evaluation of a Cyanine-Based SPECT Probe for Multimodal Tumor Necrosis Imaging

Purpose

Recently we showed that a number of carboxylated near-infrared fluorescent (NIRF) cyanine dyes possess strong necrosis avid properties in vitro as well as in different mouse models of spontaneous and therapy-induced tumor necrosis, indicating their potential use for cancer diagnostic- and prognostic purposes. In the previous study, the detection of the cyanines was achieved by whole body optical imaging, a technique that, due to the limited penetration of near-infrared light, is not suitable for investigations deeper than 1 cm within the human body. Therefore, in order to facilitate clinical translation, the purpose of the present study was to generate a necrosis avid cyanine-based NIRF probe that could also be used for single photon emission computed tomography (SPECT). For this, the necrosis avid NIRF cyanine HQ4 was radiolabeled with ¹¹¹indium, via the chelate diethylene triamine pentaacetic acid (DTPA).

Procedures

The necrosis avid properties of the radiotracer [¹¹¹In]DTPA-HQ4 were examined in vitro and in vivo in different breast tumor models in mice using SPECT and optical imaging. Moreover, biodistribution studies were performed to examine the pharmacokinetics of the probe in vivo.

Results

Using optical imaging and radioactivity measurements, in vitro, we showed selective accumulation of [¹¹¹In]DTPA-HQ4 in dead cells. Using SPECT and in biodistribution studies, the necrosis avidity of the radiotracer was confirmed in a 4T1 mouse breast cancer model of spontaneous tumor necrosis and in a MCF-7 human breast cancer model of chemotherapy-induced tumor necrosis.

Conclusions

The radiotracer [¹¹¹In]DTPA-HQ4 possessed strong and selective necrosis avidity in vitro and in various mouse models of tumor necrosis in vivo, indicating its potential to be clinically applied for diagnostic purposes and to monitor anti-cancer treatment efficacy.