Takotsubo syndrome-like model in rats with high reproducibility and low mortality

Background/Purpose

Takotsubo syndrome (TS) is an acute form of heart failure with similar mortality and clinical presentation as myocardial infarction. The pathophysiology of the potentially life-threatening syndrome is only partially understood. This experimental study aimed to produce a human-like TS model with high reproducibility and low mortality. Rats have been the small-animal model of choice for preclinical studies within the cardiovascular field, successfully translating gained knowledge to humans. A relevant animal model can aid in elucidating mechanisms behind TS and serve as a platform for developing evidence-based treatment guidelines specific for the disease, which are currently missing.

Methods

190 Sprague Dawley rats (male, ∼300 g, ∼47 d) were infused i.v. with a single dose of the β-adrenergic agonist isoprenaline. The first study group was randomized by infusion time (ranging from 1 min to 60 min) while maintaining a fixed total dose (6.25 mg/kg), and the second group by total dose (0.1–50 mg/kg) with specified infusion time. The studies were replicated with saline infusion as a control. This study looked at mortality, the incidence of apical akinesia, the extent of apical akinesia, and recovery time. ECG, HR, SpO2, and temperature were monitored during the induction phase (<60 min) and at time points for imaging. High-resolution speckle-tracking echocardiography was used to study heart function for up to 30 days. The study followed the principles of laboratory animal care and was approved by our institution's Animal Ethics Committee.

Results

Mechanical dyssynchrony preceded global contractile dysfunction and development of transient apical akinesia. LV function and contractility normalised after 1 to 7 days. All surviving rats showed normal behaviour, ECG, and imaging at 30 days. TS-like phenotype was achieved in 92.9% of survivors. Mortality at 30-day was 6.7%. The deceased animals developed complications like TS patients including heart failure, malignant arrhythmias, LV mural thrombus formation, cardiogenic shock. Longer infusion time was associated with increased mortality (p=0.002), but not with the incidence of akinesia (p=0.818). The extent of apical akinesia decreased at the shortest infusion time (1 min) while at 7.5 minutes and above, it did not differ. The replication study validated these findings, although variability in incidence and mortality was seen across the groups.

Conclusions

This study provides a highly reproducible TS-like model with low mortality and excellent translational potential. High-resolution imaging and the natural course demonstrated the presence of the most critical characteristics of TS-like phenotype as in humans. The model also validates other findings related to TS including variability in the susceptibility to develop TS-like phenotype and complications. Our model provides a solid experimental platform for future preclinical studies of TS.

Funding Acknowledgement

Type of funding sources: Public grant(s) – National budget only. Main funding source(s): ALF - Swedish Research Council

Pattern of mandibular third molar impaction: A cross-sectional study in northeast of Iran

OBJECTIVES

Impacted teeth, if left untreated, have a potential to induce various complications. The aim of the current study was to determine the prevalence and pattern of impacted mandibular third molar in the Iranian population.

STUDY DESIGN

This cross-sectional study was performed in patients who were referred to the Department of Oral Radiology between July 2009 and October 2010 to obtain an orthopantomogram (OPG). Data were collected regarding age and gender, prevalence of impacted mandibular third molars, angulation of impacted teeth (Winter's classification), level of impaction (Pell and Gregory classification), and relationship of the mandibular third molar with the ramus (Pell and Gregory classification). The collected data were analyzed using SPSS software version 11.0 with a confidence interval of 95%.

RESULTS

Among the 1433 patients included in the study, 489 (34.12%) patients were male and 944 (65.88%) were female. Of the total OPGs performed, 871 (60.78%) OPGs demonstrated at least one impacted mandibular third molar. In addition, of the 2866 mandibular third molars investigated, 1397 (48.74%) were found to be impacted. A significant association was observed between gender and the number of impacted teeth or the presence of impaction of any mandibular tooth (or teeth) (P < 0.05). The most common type of tooth angulation was mesioangular (48.67%). In addition, the most prevalent type of impaction level and ramus relationship was level B (63.85%) and Class II (48.46%), respectively. There were no significant differences between the two sides of the mandible for the prevalence of impacted third molar (P > 0.05).

CONCLUSION

The pattern of mandibular third molars in the Northeast region of Iran revealed a high prevalence of impaction, which was mostly mesioangular, level B, and Class II with a gender predilection for females.

Enhancement of emission efficiency of colloidal CdSe quantum dots on silicon substrate via an ultra-thin layer of aluminum oxide

We demonstrate that an ultra-thin layer of aluminum oxide can significantly enhance the emission efficiency of colloidal quantum dots on a Si substrate. For an ensemble of single quantum dots, our results show that this super brightening process can increase the fluorescence of CdSe quantum dots, forming well-resolved spectra, while in the absence of this layer the emission remains mostly at the noise level. We demonstrate that this process can be further enhanced with irradiation of the quantum dots, suggesting a significant photo-induced fluorescence enhancement via considerable suppression of non-radiative decay channels of the quantum dots. We study the impact of the Al oxide thickness on Si and interdot interactions, and discuss the results in terms of photo-induced catalytic properties of the Al oxide and the effects of such an oxide on the Coulomb blockade responsible for suppression of photo-ionization of the quantum dots.

Photo-induced suppression of plasmonic emission enhancement of CdSe/ZnS quantum dots

Emission of semiconductor quantum dots can be increased via two fundamentally different processes: (i) surface plasmon resonances (plasmonic emission enhancement) and (ii) irradiation with light (photo-induced fluorescence enhancement). In this paper we theoretically and experimentally study the mutual impacts of these processes on each other in quantum dot solids. We show that when thin films of colloidal quantum dots are placed in the vicinity of Au nano-islands, the plasmonic enhancement of the radiative decay rates of quantum dots and Forster energy transfer can hinder the photo-induced fluorescence enhancement of these films. This in turn leads to significant suppression of their plasmonic emission enhancement when they are irradiated with a laser beam. We investigate the impact of the sizes and shapes of the metallic nanoparticles in this process and theoretically analyze how plasmons and energy transfer can hinder the electrostatic barrier responsible for photo-induced fluorescence enhancement.

Neonatal intracranial teratoma

Brain tumors diagnosed in neonatal period are extremely rare. A case of neonatal intracranial teratoma with extracranial extension, presenting with upper airway obstruction is reported. The preoperative diagnosis was made by cranial computed tomography and magnetic resonance imaging.