Effect of troxerutin in counteracting hyperglycemia-induced VEGF upregulation in endothelial cells: a new option to target early stages of diabetic retinopathy?

Diabetic retinopathy (DR), one of the most common complications of diabetes mellitus, is characterized by degeneration of retinal neurons and neoangiogenesis. Until today, the pharmacological approaches for DR are limited and focused on counteracting the end-stage of this neurodegenerative disease, therefore efforts should be carried out to discover novel pharmacological targets useful to prevent DR development. Hyperglycemia is a major risk factor for endothelial dysfunction and vascular complication, which subsequently may trigger neurodegeneration. We previously demonstrated that, in the rat retina, hyperglycemia activates a new molecular cascade implicating, up-stream, protein kinase C ßII (PKC ßII), which in turn leads to a higher expression of vascular endothelial growth factor (VEGF), via the mRNA-binding Hu-antigen R (HuR) protein. VEGF is a pivotal mediator of neovascularization and a well-known vasopermeability factor. Blocking the increase of VEGF via modulation of this cascade can thus represent a new pharmacological option to prevent DR progression. To this aim, proper in vitro models are crucial for drug discovery, as they allow to better identify promising effective molecules. Considering that endothelial cells are key elements in DR and that hyperglycemia triggers the PKCßII/HuR/VEGF pathway, we set up two distinct in vitro models applying two different stimuli. Namely, human umbilical vein endothelial cells were exposed to phorbol 12-myristate 13-acetate, which mimics diacylglycerol whose synthesis is triggered by diabetic hyperglycemia, while human retinal endothelial cells were treated with high glucose for different times. After selecting the optimal experimental conditions able to determine an increased VEGF production, in search of molecules useful to prevent DR development, we investigated the capability of troxerutin, an antioxidant flavonoid, to counteract not only the rise of VEGF but also the activation of the PKCßII/HuR cascade in both in vitro models. The results show the capability of troxerutin to hinder the hyperglycemia-induced increase in VEGF in both models through PKCßII/HuR pathway modulation. Further, these data confirm the key engagement of this cascade as an early event triggered by hyperglycemia to promote VEGF expression. Finally, the present findings also suggest the potential use of troxerutin as a preventive treatment during the early phases of DR.

Cardiac amyloidosis detection by early bisphosphonate (99mTc-HMDP) scintigraphy.

OBJECTIVE: To determine one or more indexes able to detect the presence of cardiac amyloidosis (CA) from planar scintigraphy images after injection of 99mTc-HMDP tracer and to identify the earliest acquisition time able to ensure an accurate diagnosis of amyloid transthyretin CA. METHODS AND RESULTS: A total of 38 patients were included: 18 subjects with a final diagnosis of ATTR-CA and 20 controls. Dynamic planar images of the anterior thorax were acquired, starting at intravenous injection of ≈ 700 MBq of 99mTc-HMDP. From time/activity curves (TAC) of regions of interest such as heart, vascular region, right ribcage, and soft tissues, several indices were considered. From the analysis, it resulted that both TACHeart/Bone(t) and RIheart-bone(t), for t > 6 minutes, well distinguish ATTR-CA patients from controls subjects. This is confirmed by the area under curves (AUC) analysis giving AUC values =.9 at t ≅ 6 minutes and AUC ≅ 1 for t > 10 minutes. CONCLUSIONS: The method proposed allows determining the presence of ATTR-CA, in an inexpensive manner both in terms of examination costs and time spent.

Cardiac amyloidosis characterization by kinetic model fitting on [18F]florbetaben PET images.

OBJECTIVE: To evaluate the feasibility of kinetic modeling-based approaches from [18F]-Flobetaben dynamic PET images as a non-invasive diagnostic method for cardiac amyloidosis (CA) and to identify the two AL- and ATTR-subtypes. METHODS AND RESULTS: Twenty-one patients with diagnoses of CA (11 patients with AL-subtype and 10 patients with ATTR-subtype of CA) and 15 Control patients with no-CA conditions underwent PET/CT imaging after [18F]Florbetaben bolus injection. A two-tissue-compartment (2TC) kinetic model was fitted to time-activity curves (TAC) obtained from left ventricle wall and left atrium cavity ROIs to estimate kinetic micro- and macro-parameters. Combinations of kinetic parameters were evaluated with the purpose of distinguishing Control subjects and CA patients, and to correctly label the last ones as AL- or ATTR-subtype. Resulting sensitivity, specificity, and accuracy for Control subjects were: 0.87, 0.9, 0.89; as far as CA patients, the sensitivity, specificity, and accuracy were respectively 0.9, 1, and 0.97 for AL-CA patients and 0.9, 0.92, 0.97 for ATTR-CA patients. CONCLUSION: Pharmacokinetic analysis based on a 2TC model allows cardiac amyloidosis characterization from dynamic [18F]Florbetaben PET images. Estimated model parameters allows to not only distinguish between Control subjects and patients, but also between AL- and ATTR-amyloid patients.

Combined functional magnetic resonance imaging and skin conductance to detect localized neural response to psychological stress: a pilot study.

OBJECTIVE: This preliminary study aims at investigating the neural correlates of the stress response, intended as an emotional and cognitive response, through the description of the activation of the autonomic nervous system in a problem-solving task and central functional data; in particular, we recorded skin conductance level (SCL) and response (SCR) and observed the correlation with fMRI data. MATERIALS AND METHODS: The results obtained from 6 healthy subjects, 3 males and 3 females, aged between 18 and 45 (average = 27, SD = 7.08) who voluntarily offered to participate in the study were examined. They were previously subjected to a brief clinical psychological assessment (MMPI-2) and then to a psychophysiological evaluation. The real experiment consisted in subjecting the participants to an adapted version of the Raven's Coloured Progressive Matrices 47 (CPM 47) test to evaluate some consequences on brain activity of attention, orientation, reflex and response to stress during fMRI data acquisition and SCL-SCR recording. RESULTS: SCR changes were found to be related to the activity of different brain regions such as bilateral precentral gyrus, right inferior frontal gyrus, right medial frontal gyrus, bilateral superior frontal gyri and left anterior cingulate suggesting a specific relationship between attentive processing and autonomic arousal. CONCLUSION: The association of SC measurement with neuroimaging allows to highlight the interaction between emotional and cognitive processes: although preliminary, these results partially confirm what previously found in literature on the neural correlates of psychological stress and underline the interaction between cognitive function and autonomic arousal system during a stressful problem-solving task.

Imaging Techniques as an Aid in the Early Detection of Cardiac Amyloidosis.

The idea that performing a proper succession of imaging tests and techniques allows an accurate and early diagnosis of cardiac amyloidosis, avoiding the need to perform the myocardial biopsy, is becoming increasingly popular. Furthermore, being imaging techniques non-invasive, it is possible to perform the follow-up of the pathology through repeated image acquisitions. In the present review, the various innovative imaging methodologies are presented, and it is discussed how they have been applied for early diagnosis of cardiac amyloidosis (CA), also to distinguish the two most frequent subtypes in CA: immunoglobulin light chain amyloidosis (AL) and transthyretin amyloidosis (ATTR); this allows to perform the therapy in a targeted and rapid manner.

A Proof of Concept of a Non-Invasive Image-Based Material Characterization Method for Enhanced Patient-Specific Computational Modeling.

PURPOSE: Computational models of cardiovascular structures rely on their accurate mechanical characterization. A validated method able to infer the material properties of patient-specific large vessels is currently lacking. The aim of the present study is to present a technique starting from the flow-area (QA) method to retrieve basic material properties from magnetic resonance (MR) imaging. METHODS: The proposed method was developed and tested, first, in silico and then in vitro. In silico, fluid-structure interaction (FSI) simulations of flow within a deformable pipe were run with varying elastic modules (E) between 0.5 and 32 MPa. The proposed QA-based formulation was assessed and modified based on the FSI results to retrieve E values. In vitro, a compliant phantom connected to a mock circulatory system was tested within MR scanning. Images of the phantom were acquired and post-processed according to the modified formulation to infer E of the phantom. Results of in vitro imaging assessment were verified against standard tensile test. RESULTS: In silico results from FSI simulations were used to derive the correction factor to the original formulation based on the geometrical and material characteristics. In vitro, the modified QA-based equation estimated an average E = 0.51 MPa, 2% different from the E derived from tensile tests (i.e. E = 0.50 MPa). CONCLUSION: This study presented promising results of an indirect and non-invasive method to establish elastic properties from solely MR images data, suggesting a potential image-based mechanical characterization of large blood vessels.

Systemic Inflammation after Third Molar Removal: A Case-Control Study.

Third molar extraction is one of the most frequent interventions in dentistry. Nevertheless, there is scarce evidence on the host response of individuals with impacted or semi-impacted third molars and the possible effects of surgical removal. A case-control study of 40 patients was designed to evaluate 1) the differences in biomarkers of systemic inflammation, vascular function, and metabolism (high-sensitive C-reactive protein, lipids, fibrinogen, oxidative stress, and endothelial function analysis) and 2) the acute and short-term effects of surgical removal in patients with bilateral impacted or semi-impacted third molars compared to controls with no third molars. Patients undergoing third molar extraction exhibited greater levels of systemic inflammation, oxidative stress, and triglycerides than controls. Raised white blood cell counts as well as peaks of serum levels of C-reactive protein and fibrinogen were noticed in the first postoperative week. Three months after the extraction, all markers returned to baseline values. Malondialdehyde, an indicator of oxidative stress indicator, was significantly reduced after third molar removal. Semi-impacted or impacted third molars are associated with higher systemic inflammation, and their removal may represent a useful human model to study acute inflammation and determine beneficial systemic effects ( ClinicalTrials.gov NCT03048175).

Dentigerous cysts associated with impacted third molars in adults after decompression: a prospective survey of reduction in volume using computerised analysis of cone-beam computed tomographic images.

We prospectively investigated in adults the decompression of dentigerous cysts associated with impacted third molars at high risk of iatrogenic damage during extraction. The computerised calculated volumetric postoperative reductions measured by cone-beam computed tomography at four and eight months were correlated with the duration of treatment, initial volume, and patient's age. We prospectively monitored 14 adult patients with 14 dentigerous cysts that were associated with impacted third molars, for eight months after decompression. The mean (SD) reduction in volume during the first eight months was 71 (14) % (51% after the first four months and 20% after the second four months), with a monthly reduction rate of 9%. Both the total decrease in volume (a) and the monthly rate of reduction (b) were significantly associated (p<0.01) and linearly correlated with the duration of decompression [r (a)=-0.89, r (b)=-0.61] and initial volume [r (a)=r (b)=0.92], but not with the patient's age (p=0.49) [r (a)=r (b)=0.04]. The trend towards reduction in volume within a period of eight months of treatment allowed us to better understand the duration of decompression required.

Analysis of Residual Dependencies of Independent Components Extracted from fMRI Data.

Independent component analysis (ICA) of functional magnetic resonance imaging (fMRI) data can be employed as an exploratory method. The lack in the ICA model of strong a priori assumptions about the signal or about the noise leads to difficult interpretations of the results. Moreover, the statistical independence of the components is only approximated. Residual dependencies among the components can reveal informative structure in the data. A major problem is related to model order selection, that is, the number of components to be extracted. Specifically, overestimation may lead to component splitting. In this work, a method based on hierarchical clustering of ICA applied to fMRI datasets is investigated. The clustering algorithm uses a metric based on the mutual information between the ICs. To estimate the similarity measure, a histogram-based technique and one based on kernel density estimation are tested on simulated datasets. Simulations results indicate that the method could be used to cluster components related to the same task and resulting from a splitting process occurring at different model orders. Different performances of the similarity measures were found and discussed. Preliminary results on real data are reported and show that the method can group task related and transiently task related components.

Analysis of the microcirculatory pulse wave: age-related alterations.

Morphological analysis of the pulse wave of central blood pressure signal is commonly used for the study of cardiac and vascular properties, but very few attempts were performed for analyzing the peripheral pulse wave of blood flow. In this work, we analyzed this waveform using classical methods, based on the application of FFT, followed by principal components analysis, for assessing the properties of the blood flow. As a sample problem, we evaluated the capability of the proposed method of assessing the alterations correlated with the aging of the vascular system. Results show a good discrimination between the different age groups, confirming the validity of the approach.

Models and Methods in Cardiac Imaging for Metabolism Studies.

Cardiac health depends on the heart's ability to utilize different substrates to support overall oxidative metabolism. To characterize a variety of cardiac diseases, there is an ever-growing demand for an accurate non-invasive approach to evaluating myocardial substrate metabolism. Data obtained from quantitative metabolic imaging modalities add functional information to the anatomic imaging modalities and can aid patient management. The goal of this review is to emphasize the role of non-invasive imaging techniques (such as PET, SPECT, MR spectroscopy and spectroscopic imaging) to detect the metabolic footprints of heart disease. The advancements of models and methods to estimate kinetic parameters of dynamic processes using data acquired from cardiac imaging modalities is discussed.

Type 2 diabetes mellitus worsens arterial stiffness in hypertensive patients through endothelial dysfunction.

AIMS/HYPOTHESIS: Endothelium-derived factors are thought to be physiological modulators of large artery stiffness. The aim of the study was to investigate whether endothelial function could be a determinant of arterial stiffness in essential hypertensive patients, in relation with the concomitant presence of type 2 diabetes mellitus. METHODS: The study included 341 participants (84 hypertensive patients with and 175 without type 2 diabetes mellitus, 82 matched controls). Brachial artery endothelium-dependent flow-mediated dilation (FMD) was determined by high-resolution ultrasound and computerised edge detection system. Applanation tonometry was used to measure carotid-femoral pulse wave velocity (PWV). RESULTS: Hypertensive patients with diabetes had higher PWV (10.1 ± 2.3 m/s vs 8.6 ± 1.4 m/s, p < 0.001) and lower FMD (3.51 ± 2.07 vs 5.16 ± 2.96%, p < 0.001) than non-diabetic hypertensive patients, who showed impaired vascular function when compared with healthy participants (7.9 ± 1.6 m/s and 6.68 ± 3.67%). FMD was significantly and negatively correlated to PWV only in hypertensive diabetic patients (r = -0.456, p < 0.001), but not in hypertensive normoglycaemic patients (r = -0.088, p = 0.248) or in healthy participants (r = 0.008, p = 0.946). Multivariate analysis demonstrated that, in the diabetic group, FMD remained an independent predictor of PWV after adjustment for confounders (r(2) = 0.083, p = 0.003). Subgroup analysis performed in non-diabetic hypertensive patients revealed that neither obesity nor the metabolic syndrome affected the relationship between FMD and PWV. CONCLUSIONS/INTERPRETATION: Endothelial dysfunction is a determinant of aortic stiffness in hypertensive diabetic patients but not in hypertensive patients without diabetes. These results suggest that type 2 diabetes mellitus on top of hypertension might worsen arterial compliance by endothelium-related mechanisms.

Dynamic evaluation of renal resistive index in normoalbuminuric patients with newly diagnosed hypertension or type 2 diabetes.

AIM/HYPOTHESIS: Renal resistive index is a useful measure for quantifying alterations in renal blood flow. In the present study we evaluated resistive index at baseline and after vasodilation induced by nitroglycerine in normoalbuminuric patients with type 2 diabetes or essential hypertension, relating the values to indices of systemic vascular dysfunction. METHODS: Newly diagnosed treatment-naïve type 2 diabetic (n = 32) and hypertensive patients (n = 49) were compared with 27 age- and sex-matched healthy controls. Renal resistive index was obtained by duplex ultrasound at baseline and after 25 µg sublingual nitroglycerine. Endothelium-dependent (flow-mediated dilation) and -independent (response to nitroglycerine) vasodilation in the brachial artery was assessed by computerised edge detection system. Carotid-femoral pulse-wave velocity and augmentation index were assessed by applanation tonometry. Nitrotyrosine levels, an index of oxidative stress, were also measured. RESULTS: Resistive index was higher in diabetic than in hypertensive patients and controls (p < 0.001), while changes in resistive index induced by nitroglycerine were lower in hypertensive patients compared with controls (p < 0.01), and were further reduced in type 2 diabetic patients. Hypertensive and diabetic patients showed significantly increased arterial stiffness, nitrotyrosine levels and reduced endothelial function than controls (p < 0.05). Changes in resistive index induced by nitroglycerine were independently related to serum glucose, reactive hyperaemia and aortic pulse-wave velocity in the overall population. CONCLUSIONS/INTERPRETATION: These results support the dynamic evaluation of renal resistive index as an early detector of renal vascular alterations in the presence of type 2 diabetes and hypertension, even before the onset of microalbuminuria.

Noise correlations and SNR in phased-array MRS.

The acquisition of magnetic resonance spectroscopy (MRS) signals by multiple receiver coils can improve the signal-to-noise ratio (SNR) or alternatively can reduce the scan time maintaining a reliable SNR. However, using phased array coils in MRS studies requires efficient data processing and data combination techniques in order to exploit the sensitivity improvement of the phased array coil acquisition method. This paper describes a novel method for the combination of MRS signals acquired by phased array coils, even in presence of correlated noise between the acquisition channels. In fact, although it has been shown that electric and magnetic coupling mechanisms produce correlated noise in the coils, previous algorithms developed for MRS data combination have ignored this effect. The proposed approach takes advantage of a noise decorrelation stage to maximize the SNR of the combined spectra. In particular Principal Component Analysis (PCA) was exploited to project the acquired spectra in a subspace where the noise vectors are orthogonal. In this subspace the SNR weighting method will provide the optimal overall SNR. Performance evaluation of the proposed method is carried out on simulated (1)H-MRS signals and experimental results are obtained on phantom (1)H-MR spectra using a commercially available 8-element phased array coil. Noise correlations between elements were generally low due to the optimal coil design, leading to a fair SNR gain (about 0.5%) in the center of the field of view (FOV). A greater SNR improvement was found in the peripheral FOV regions.

Objective selection of EEG late potentials through residual dependence estimation of independent components.

This paper presents a novel method to objectively select electroencephalographic (EEG) cortical sources estimated by independent component analysis (ICA) in event-related potential (ERP) studies. A proximity measure based on mutual information is employed to estimate residual dependences of the components that are then hierarchically clustered based on these residual dependences. Next, the properties of each group of components are evaluated at each level of the hierarchical tree by two indices that aim to assess both cluster tightness and physiological reliability through a template matching process. These two indices are combined in three different approaches to bring to light the hierarchical structure of the cluster organizations. Our method is tested on a set of experiments with the purpose of enhancing late positive ERPs elicited by emotional picture stimuli. Results suggest that the best way to look for physiologically plausible late positive potential (LPP) sources is to explore in depth the tightness of those clusters that, taken together, best resemble the template. According to our results, after brain sources clustering, LPPs are always identified more accurately than from ensemble-averaged raw data. Since the late components of an ERP involve the same associative areas, regardless of the modality of stimulation or specific tasks administered, the proposed method can be simply adapted to other ERP studies, and extended from psychophysiological studies to pathological or sport training evaluation support.

Rinite alérgica / Allergic rhinitis

A rinite alérgica representa um problema de saúde pública, apresentando um impacto econômico e social cada vez maior. É a forma mais comum de todas as rinites, afetando cerca de 25% a 35% dos indivíduos adultos, embora sua prevalência seja subestimada. Esta doença pode afetar seriamente a qualidade de vida dos pacientes, sendo uma causa de desconforto físico e emocional, e está associada com múltiplas afecções, como asma, rinossinusite, otite média secretora e pólipos nasais. O adequado tratamento da rinite alérgica requer que um diagnóstico correto seja feito: a história clínica e o exame físico são fundamentais. Estudos controlados apoiam a utilidade de diversas opções terapêuticas disponíveis, que diminuem os sintomas, melhoram a qualidade de vida e previnem comorbidades. Uma abordagem que inclua evitar o contato com alérgenos, tratamento farmacológico e imunoterapia ajuda a reduzir a progressão do processo inflamatório. A farmacoterapia é a modalidade terapêutica mais empregada. Os anti-histamínicos de segunda geração são preferíveis, por causa da baixa sedação e efeitos anticolinérgicos. Os corticosteroides tópicos intranasais permanecem como o melhor método terapêutico para o tratamento da rinite alérgica sazonal (intermitente) e perene (persistente). Evitar os alérgenos é recomendado, mas pode ser de difícil realização, dependendo do fator desencadeante. A imunoterapia deve ser considerada em face de uma má resposta à farmacoterapia e à evitação dos alérgenos.

Molecular and biochemical changes of the cardiovascular system due to smoking exposure.

Cigarette smoking (CS) is a major health hazard particularly for the cardiovascular system and cancer. The mechanisms involved in CS-related cardiovascular dysfunction have been largely debated. CS increases inflammation, thrombosis, and oxidation of low-density lipoproteins. Recent experimental and clinical data support the hypothesis that cigarette smoke exposure increases oxidative stress as a potential mechanism for initiating cardiovascular dysfunction. Cardiac myocytes, as well as and other long-lived postmitotic cells show dramatic smoke-related alterations that mainly affect the mitochondria and lysosomal compartment. Mitochondria are primary sites of reactive oxygen species formation that cause progressive damage to mitochondrial DNA and proteins in parallel to intralysosomal lipofuscin accumulation. There is amassing evidence that various mechanisms may contribute to accumulation of damaged mitochondria following initial oxidative injury. Such mechanisms may include clonal expansion of defective mitochondria, decreased propensity of altered mitochondria to become autophagocytosed, suppressed autophagy because of heavy lipofuscin loading of lysosomes and decreased efficiency of specific proteases involved into mitochondrial degradation. A possible interplay between microtubule plasticity and oxidative stress also exists in cardiomyocytes, so this could represent another potential mechanism by which smoking induces/accelerates atherosclerosis.

The biological effects of diagnostic cardiac imaging.

In this paper the authors deal with the main imaging techniques available to clinical cardiologists, with a brief overview of biophysical and biological aspects which are of relevance for the assessment of health effects related to the exposure of patients to both ionizing and non ionizing radiation. A main contribute is the reviewing published evidence on biological effects of radiation, trying to compose a balanced issue in order to increase awareness and knowledge about radiation exposure from cardiac imaging and implications for health risk.

Evaluation of a web-based network for reproducible T2* MRI assessment of iron overload in thalassemia.

PURPOSE: To build and evaluate a national network able to improve the care of thalassemia, a genetic disorder in haemoglobin synthesis often associated with iron accumulation in a variety of organs, due to the continuous blood transfusions. METHODS: The MIOT (Myocardial Iron Overload in Thalassemia) network is constituted by thalassemia and magnetic resonance imaging (MRI) centers. Thalassemia centers are responsible for patient recruitment and collection of anamnestic and clinical data. MRI centers have been equipped with a standardized acquisition technique and an affordable workstation for image analysis. They are able to perform feasible and reproducible heart and liver iron overload assessments for a consistent number of thalassemia patients in a robust manner. All centers are linked by a web-based network, configured to collect and share patient data. RESULTS: On 30th March 2008, 695 thalassemia patients were involved in the network. The completion percentage of the patient records in the database was 85+/-6.5%. Six hundred and thirteen patients (88%) successfully underwent MRI examination. Each MRI center had a specific absorption capacity that remained constant over time, but the network was capable of sustaining an increasing number of patients due to continuous enrollment of new centers. The patient's comfort, assessed as the mean distance from the patient home locations to the MRI centers, significantly increased during the network's evolution. CONCLUSION: The MIOT network seems to be a robust and scalable system in which T2* MRI-based cardiac and liver iron overload assessment is available, accessible and reachable for a significant and increasing number of thalassemia patients in Italy (about 420 per year), reducing the mean distance from the patient locations to the MRI sites from 951km to 387km. A solid, wide and homogeneous database will constitute an important scientific resource, shortening the time scale for diagnostic, prognostic and therapeutical evidence-based research on the management of thalassemia disease.