Prevention of Excessive Endothelin-1 Release in Sclerotherapy: In Vitro and In Vivo Studies.

Abstract BACKGROUND The foam sclerotherapy technique has become one of the most commonly used treatments for superficial venous insufficiency. Despite excellent results, few visual/neurologic disturbances have been recently reported; their pathogenesis is still debated but a correlation with endothelin-1 (ET-1) release from the treated vein has been proposed. OBJECTIVE The purpose of this work was to evaluate the ET-1 release after sclerotherapy and to investigate the effects of the anti-endothelin drug aminaphtone. METHODS AND MATERIALS As in vitro sclerotherapy model, an endothelial cell culture, mimicking vascular endothelium, was pretreated with aminaphtone and exposed to detergents. Cell survival and ET-1 release were measured. In in vivo experiments, 45 rats, fed with different aminaphtone-rich diets, were subjected to sclerotherapy, and the systemic ET-1 was measured. RESULTS A minaphtone cell exposure caused a statistically significant reduction in ET-1 release, both before and after in vitro sclerotherapy. Rats fed with aminaphtone showed a trend toward reduced mortality and a significant decrease of ET-1 release after sclerotherapy. CONCLUSION This is the first study in which an anti-endothelin agent was able to cause a significant reduction of ET-1 release during sclerotherapy. Although clinical studies are required, these findings might advocate the use of anti-endothelin agents in prophylaxis of neurologic or visual disturbances after sclerotherapy

Subthreshold bipolar atrial stimulation affects the discharge rate of the sinus node: an animal study

Aim of this study was to verify whether the electrical field generated inside the right atrium by sub-threshold electrical impulses (impulses unable to induce cells activation) may condition the discharge rate of the sinus node cells. An electrophysiological study was performed on seven young farm pigs before and after denervation. After general anesthesia, pigs were stimulated with impulses delivered at constant rate by a bipolar catheter positioned inside the right atrium. The amplitude of the stimulus was set to avoid atrial capture. A 10-minute atrial stimulation was performed at a rate above and below the spontaneous heart rate, both before and after denervation. Three animals showed a conditioning of the sinus rhythm, observed as phase synchronization. The different response, or even the no response, of animals to stimulation could be due to different factors, concerning biological, pharmacological and "geometric" conditions. The important result remains that a perturbation of the sinus rhythm can be induced by a very low electrical field, as the one generated by the activity of artificial pacemakers, and it could help explaining the onset of rhythm disturbances in paced patients

SYNCHRONIZATION INDUCED BY PACED ATRIAL SUBTHRESHOLD STIMULATION ON THE SINUS NODE ACTIVITY IN ANIMAL EXPERIMENT

Synchronization is the well-known phenomenon that indicates adjustment of frequencies of weakly interacting self-sustained periodic oscillators [1]. Besides the physics environment, synchronization is often encountered even in physiological systems exhibiting oscillatory behaviour. Above all others, the heart, the biological oscillator par excellence, has been object of a number of investigations. At the cellular level interesting experiments were carried out on spontaneously beating aggregates of cardiac cells from embryonic chicken heart stimulated with single impulse or impulses of different amplitudes and frequencies [2]. These experiments evidenced the interaction between stimuli and cardiac cells activity in terms of phase resetting (single stimulus) and synchronization (train of impulses). Aim of this study was to verify whether the electrical field generated inside the right atrium by subthreshold electrical impulses (impulses unable to induce cells activation) may condition the discharge rate of the sinus node cell

Simulation, design, and test of an elliptical surface coil for magnetic resonance imaging and spectroscopy

AbstractThe simplest design of surface coils for magnetic resonance imaging (MRI) applications is circular and square loops, both producing a magnetic field perpendicular to the coil plane in the central region‐of‐interest (ROI), with an amplitude that decreases along the coil axis. However, a surface coil constituted by a loop with different geometry could be necessary when particular field‐of‐views (FOVs) are desired, especially for performing imaging in an elongated region. This can be achieved by using an elliptical loop, which can guarantee a wide longitudinal FOV and a good penetration in deep sample regions. This work proposes the application of a method for elliptical coil Signal‐to‐Noise Ratio (SNR) estimation previously developed for circular and square loop design, in which coil inductance and resistance are analytically calculated and the magnetic field pattern is estimated using the magnetostatic approach, while the sample‐induced resistance is calculated with the vector potential calculation method. In the second part of the paper, we propose the simulation and the design of a transmit/receive elliptical coil for MRI in mice with a 3T clinical scanner. We also evaluated the coil performance in a preliminary magnetic resonance spectroscopy (MRS) study in phantom

Maternal and Sex Dependency of Insulin Resistance: Longitudinal PET and Echocardiography Study from the Healthy Fetus to the Adult Minipig

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Combined Effect of Fatty Diet and Cognitive Decline on Brain Metabolism, Food Intake, Body Weight, and Counteraction by Intranasal Insulin Therapy in 3×Tg Mice

Obesity and cognitive decline can occur in association. Brain dysmetabolism and insulin resistance might be common underlying traits. We aimed to examine the effect of high-fat diet (HFD) on cognitive decline, and of cognitive impairment on food intake and body-weight, and explore efficacy of chronic intranasal insulin (INI) therapy. We used control (C) and triple transgenic mice (3×Tg, a model of Alzheimer’s pathology) to measure cerebral mass, glucose metabolism, and the metabolic response to acute INI administration (cerebral insulin sensitivity). Y-Maze, positron emission-computed tomography, and histology were employed in 8 and 14-month-old mice, receiving normal diet (ND) or HFD. Chronic INI therapy was tested in an additional 3×Tg-HFD group. The 3×Tg groups overate, and had lower body-weight, but similar BMI, than diet-matched controls. Cognitive decline was progressive from HFD to 3×Tg-ND to 3×Tg-HFD. At 8 months, brain fasting glucose uptake (GU) was increased by C-HFD, and this effect was blunted in 3×Tg-HFD mice, also showing brain insulin resistance. Brain mass was reduced in 3×Tg mice at 14 months. Dentate gyrus dimensions paralleled cognitive findings. Chronic INI preserved cognition, dentate gyrus and metabolism, reducing food intake, and body weight in 3×Tg-HFD mice. Peripherally, leptin was suppressed and PAI-1 elevated in 3×Tg mice, correlating inversely with cerebral GU. In conclusion, 3×Tg background and HFD exert additive (genes*lifestyle) detriment to the brain, and cognitive dysfunction is accompanied by increased food intake in 3×Tg mice. PAI-1 levels and leptin deficiency were identified as potential peripheral contributors. Chronic INI improved peripheral and central outcomes

Heart and liver connexin expression related to the first stage of aging: A study on naturally aged animals

Connexins are membrane-spanning proteins that form membrane channels and hemichannels. They are involved in the cellular communication and in the maintenance of tissue homeostasis. Recent studies in humans and animals have demonstrated that the expression and distribution of Cx43, the most studied connexin, can change during aging. However, the research on the involvement of the other connexins in cardiac and hepatic aging is, at present, still very poor. Hence, the aim of this study is to evaluate the expression of Cx43 and Cx26 in the heart as well as Cx26 and Cx32 in the liver of a rat model that aged naturally, rather than prematurely because of genetic mutations or age-related diseases. The results obtained in the present study have demonstrated that these connexins decrease in rat cardiomyocytes and in rat hepatocytes as they age. This change was revealed only at protein level, as connexin-mRNAs remained unchanged during aging. Moreover, the aged rats showed an increase in body fat, whose subcutaneous layer tended to be higher. Finally, how these changes could represent signs of physiological adaptation in successful aging was discussed

Performance evaluation of the CT component of the IRIS PET/CT preclinical tomograph

In this paper, we evaluate the physical performance of the CT component of the IRIS scanner, a novel combined PET/CT scanner for preclinical imaging. The performance assessment is based on phantom measurement for the determination of image quality parameters (spatial resolution, linearity, geometric accuracy, contrast to noise ratio) and reproducibility in dynamic (4D) imaging. The CTDI100 has been measured free in air with a pencil ionization chamber, and the animal dose was calculated using Monte Carlo derived conversion factors taken from the literature. The spatial resolution at the highest quality protocol was 6.9 lp/mm at 10% of the MTF, using the smallest reconstruction voxel size of 58.8 μm. The accuracy of the reconstruction voxel size was within 0.1%. The linearity of the CT numbers as a function of the concentration of iodine was very good, with R2>0.996 for all the tube voltages. The animal dose depended strongly on the scanning protocol, ranging from 158 mGy for the highest quality protocol (2 min, 80 kV) to about 12 mGy for the fastest protocol (7.3 s, 80 kV). In 4D dynamic modality, the maximum scanning rate reached was 3.1 frames per minute, using a short-scan protocol with 7.3 s of scan time per frame at the isotropic voxel size of 235 μm. The reproducibility of the system was high throughout the 10 frames acquired in dynamic modality, with a standard deviation of the CT values of all frames <8 HU and an average spatial reproducibility within 30% of the voxel size across all the field of view. Example images obtained during animal experiments are also shown

Brain glucose overexposure and lack of acute metabolic flexibility in obesity and type 2 diabetes: a PET-[18F]FDG study in Zucker and ZDF rats

Brain glucose exposure may complicate diabetes and obesity. We used positron emission tomography with 18F-fluorodeoxyglucose in Zucker obese, diabetic, and control rats to determine the contributions of blood glucose mass action versus local mechanisms in regulating central glucose disposal in fasted and acutely glucose-stimulated states, and their adaptations in obesity and diabetes. Our study data indicate that brain glucose uptake is dependent on both local and mass action components, and is stimulated by acute glucose intake in healthy rats. In diseased animals, the organ was chronically overexposed to glucose, due to high fasting glucose uptake, almost abolishing the physiologic response to glucose loading

Expression of connexin-26 in mammalian cardiomyocytes

Background. Connexins (Cxs) form membrane channels which play essential role in the propagation of electrical activity throughout the heart. Their dysfunction has been linked to congenital malformation of the heart and to a wide variety of cardiac pathologies. Over twenty isoforms of Cxs have been recognized in mammalian and they are classified according to their molecular weight. To date, seven isoforms, namely Cx30.2, Cx37, Cx40, Cx43, Cx45, Cx46 and Cx57, have been found expressed in cardiac myocites. Here, preferentially located at the intercalated disks, Cxs form gap junctions allowing the intercellular exchange of 1-1.8 kDa molecules as electrical signals, small metabolites and second messengers. However, in other tissues, has been demonstrated that Cxs may also organize in connexons free at the plasma membrane, coupling intracellular and extracellular compartments or may be involved in the modulation of cell proliferation and tumor progression, interacting with intracellular protein as oncogene products, protein kinases and cytoskeleton elements. Cx26 is present in a number of tissues, and its mutations are frequently associated with deafness and skin diseases. Altered expression of Cx26 at level of colonic smooth muscle cells may predispose to the formation of diverticular lesions. The reduced expression of Cx26 may contribute to low sensitivity of hepatocellular carcinoma to chemotherapeutic agent oxaliplatin. Purpose. The aim of this study was to demonstrate the presence of Cx26 expression also in human, pig, rat and mouse cardiomyocites. Methods. Paraffin embedded sections of human auricle, pig ventricle, mouse whole heart and H9c2 cardiac rat cell line were used. Several methods were employed to test the expression of Cx26. In particular, different immunocytochemical techniques were performed using two different primary antibodies, one of which raised against a peptide near the C-terminus and the other against a segment of cytoplasmic loop of Cx26. The isotype specificity of the antibodies was verified both by western blot and by immunoperoxidase on control tissues. Real-Time PCR was used to reveal the expression of Cx26-mRNA in H9c2 cells. Results. The presence of Cx26 has been revealed in all mammalian cardiac tissues analyzed by both the two primary antibodies used. In particular, immunoperoxidase positivity was revealed in both working and specific cardiomyocytes of ventricle and atrium. Interestingly, this Cx has been found localized scattered throughout the cytoplasm of the cells but it was not revealed at level of intercalar disks where the other cardiac Cxs are mainly located. Indeed, immunofluorescence double staining using both Cx26 and Cx43 specific antibodies, showed different localization of these Cxs, in the cytoplasm and in the intercalar disks respectively. Cx26 protein expression was also demonstrated in the cytoplasm of H9c2 rat cardiac myoblasts by immunocytochemistry confirming the data obtained on Cx26-mRNA expression by RT-PCR in this cells. Conclusion. In our knowledge, this is the first study demonstrating the presence of Cx26 in mammalian cardiomyocites. Cx26 cell localization could evoke a function for this protein in signal transduction rather than in the formation of gap junctions. Other studies are in progress to test the role of this connexin in the heart and its possible involvement in cardiac disease