Effect of bradykinin on nitric oxide production, urea synthesis and viability of rat hepatocyte cultures

BACKGROUND: It is well known that cytotoxic factors, such as lipopolysaccharides, derange nitrogen metabolism in hepatocytes and nitric oxide (NO) is involved among the other factors regulating this metabolic pathway. Hepatocytes have been shown to express large levels of NO following exposure to endotoxins, such as bacterial lipopolysaccharide and/or cytokines, such as tumour necrosis factor-α (TNFα), interleukin-1. The control role of arginine in both urea and NO biosynthesis is well known, when NO is synthesized from arginine, by the NOS reaction, citrulline is produced. Thus, the urea cycle is bypassed by the NOS reaction. Many authors demonstrated in other cellular types, like cardiomyocytes, that bradykinin caused the increase in reactive oxygen species (ROS) generation. The simultaneous increase of NO and ROS levels could cause peroxynitrite synthesis, inducing damage and reducing cell viability. The aim of this research is to study the effect of bradykinin, a proinflammatory mediator, on cell viability and on urea production in cultures of rat hepatocytes. RESULTS: Hepatocytes were treated with bradykinin, that stimulates nitric oxide synthase (NOS). NO release was determined using 4,5 diaminofluorescein diacetate (DAF-2DA), as fluorescent indicator of NO. Addition of the NOS inhibitor, N(g)-nitro-L-arginine methyl ester (L-NAME), to the culture medium inhibited the increase of NO production. Exposure of hepatocytes to bradykinin 0,1 mM for 2 hours resulted in a significant decrease of urea synthesis. Cell viability, instead, showed a significant decrease 24 hours after the end of bradykinin treatment as determined by 3-(4,5-dimethyl-2-thiazolyl)-2,5diphenyl-2H-tetrazolium (MTT) assay. L-NAME addition recovered urea production and cell viability at control values. CONCLUSION: The findings suggest that the cell toxicity, after bradykinin treatment, effectively depends upon exposure to increased NO levels and the effects are prevented by L-NAME. The results show also that the increased NO synthesis induces a reduced urea production, that is another index of cell damage

3D thermal monitoring of jointed rock masses through infrared thermography and photogrammetry

The study of strain effects in thermally-forced rock masses has gathered growing interest from engineering geology researchers in the last decade. In this framework, digital photogrammetry and infrared thermography have become two of the most exploited remote surveying techniques in engineering geology applications because they can provide useful information concerning geomechanical and thermal conditions of these complex natural systems where the mechanical role of joints cannot be neglected. In this paper, a methodology is proposed for generating point clouds of rock masses prone to failure, combining the high geometric accuracy of RGB optical images and the thermal information derived by infrared thermography surveys. Multiple 3D thermal point clouds and a high-resolution RGB point cloud were separately generated and co-registered by acquiring thermograms at different times of the day and in different seasons using commercial software for Structure from Motion and point cloud analysis. Temperature attributes of thermal point clouds were merged with the reference high-resolution optical point cloud to obtain a composite 3D model storing accurate geometric information and multitemporal surface temperature distributions. The quality of merged point clouds was evaluated by comparing temperature distributions derived by 2D thermograms and 3D thermal models, with a view to estimating their accuracy in describing surface thermal fields. Moreover, a preliminary attempt was made to test the feasibility of this approach in investigating the thermal behavior of complex natural systems such as jointed rock masses by analyzing the spatial distribution and temporal evolution of surface temperature ranges under different climatic conditions. The obtained results show that despite the low resolution of the IR sensor, the geometric accuracy and the correspondence between 2D and 3D temperature measurements are high enough to consider 3D thermal point clouds suitable to describe surface temperature distributions and adequate for monitoring purposes of jointed rock mass

Role of VEGF, Nitric Oxide, and Sympathetic Neurotransmitters in the Pathogenesis of Tendinopathy: A Review of the Current Evidences

Chronic tendinopathy is a painful common condition affecting athletes as well as the general population undergoing to tendon overuse. Although its huge prevalence, little is known about tendinopathy pathogenesis, and even cloudier is its treatment. Traditionally, tendinopathy has been defined as a lack of tendon ability to overcome stressing stimuli with appropriate adaptive changes. Histologic studies have demonstrated the absence of inflammatory infiltrates, as a consequence conventional antinflammatory drugs have shown little or no effectiveness in treating tendinopathies. New strategies should be therefore identified to address chronic tendon disorders. Angiofibroblastic changes have been highlighted as the main feature of tendinopathy, and vascular endothelial growth factor (VEGF) has been demonstrated as one of the key molecules involved in vascular hyperplasia. More recently, attention has been focused on new peptides such as Substance P, nitric oxide, and calcitonin gene-related peptide (CGRP). Those new findings support the idea of a nerve-mediated disregulation of tendon metabolism. Each of those molecules could be a target for new treatment options. This study aimed to systematically review the current available clinical and basic science in order to summarize the latest evidences on the pathophysiology and its effect on treatment of chronic tendinopathy, and to spread suggestions for future research on its treatment

Conjugated polymers for the optical control of the electrical activity of living cells

Different conjugated polymers are proposed as bio-optical interfaces. Selected polymers are capable to sustain thermal sterilization but provide different optical coupling with living cells

Dental and Dental Hygiene Students' Knowledge and Capacity to Discriminate the Developmental Defects of Enamel: A Self-Submitted Questionnaire Survey.

Background: A prompt and accurate diagnosis of developmental defects of enamel (DDE) is mandatory for proper treatment management. This cross-sectional survey, designed and carried out using anonymous self-administered questionnaires, aimed to assess dental and dental hygiene students' knowledge and their capability to identify different enamel development defects. Methods: The questionnaire consisted of twenty-eight closed-ended questions. Two different samples of undergraduate students were selected and enrolled: a group of dental hygiene (GDH) students and a group of dental (GD) students. A multivariate logistic regression was performed by adopting the correct answers as explanatory variables to assess the difference between the two groups. Results: Overall, 301 completed questionnaires were analyzed: 157 from the GDH and 144 from the GD. The dental student group showed better knowledge than the GDH of enamel hypomineralization and hypoplasia (p = 0.03 for both). A quarter (25.25%) of the total sample correctly identified the period of development of dental fluorosis with a statistically significant difference between the groups (p < 0.01). Amelogenesis imperfecta (AI) was identified as a genetic disease by 64.45% of the sample, with a better performance from the GD (p = 0.01), while no statistical differences were found between the groups regarding molar incisor hypomineralization. Multivariate analysis showed that AI (OR = 0.40, [0.23;0.69], p < 0.01) and caries lesion (OR = 0.58, [0.34;0.94], p = 0.03) were better recognized by the GD. Conclusions: Disparities exist in the knowledge and management of DDE among dental and dental hygiene students in Italy; however, significant knowledge gaps were found in both groups. Education on the diagnosis and treatment of DDE during the training for dental and dental hygiene students needs to be strongly implemented

Organic electronics allows the photo-electric excitation and inhibition of neuronal activity in primary neuronal cultures and acute retinal explants

Interfacing organic electronics and biology offers new possibilities in biotechnology, due to the unique properties exhibited by organic conducting polymers (e.g. biological affinity, mechanical flexibility, ease of functionalization and cost effectiveness). Organic conducting polymers have been exploited as materials for cellular interfaces in several fashions as: (i) passive electrode coatings or culturing substrates, (ii) organic biosensors or (iii) actuators for neurotransmitter release and electrodes for controlled cell seeding, growth and activity detection. Very recently, an organic photovoltaic donor-acceptor blend has been exploited for neuron stimulation by a photo-electric process. With respect to previous examples with inorganic semiconductors, this system has several advantages including flexibility, no power requirement and biocompatibility. Here, we report the novel use of a single component semiconductor organic polymer for the direct control of neuronal activity. This interface, that is more efficient than the classical bulk hetero-junction interface, has the remarkable capability to evoke excitation of neuronal firing in response to illumination. We demonstrate that the polymer layer has the ability to induce action potential firing up to 20 Hz in cultured hippocampal neurons. Moreover, this interface has been exploited to restore visual response in retinal explants obtained from animal models of retinal degeneration (light-blinded albino SD rats). By recording local field potentials in the RGC layer, we demonstrated the ability of the organic conductive polymer to mimic the function of photoreceptors and induce retinal activation of retinal ganglion cells after light illumination. These results paved the way to the development of a new and disruptive technology for interfacing artificial devices with neuronal networks, with applications in neuroprosthesis and brain machine interface research

DWI-MR and PET-CT Functional Imaging for Boost Tumor Volume Delineation in Neoadjuvant Rectal Cancer Treatment

BACKGROUND/AIM T2 weighted magnetic resonance (MR) imaging is the gold standard for locally advanced rectal cancer (LARC) staging. The potential benefit of functional imaging, as diffusion-weighted MR (DWI) and positron emission tomography-computed tomography (PET-CT), could be considered for treatment intensification strategies. Dose intensification resulted in better pathological complete response (pCR) rates. This study evaluated the inter-observer agreement between two radiation oncologists, and the difference in gross tumor volume (GTV) delineation in simulation-CT, T2-MR, DWI-MR, and PET-CT in patients with LARC. PATIENTS AND METHODS Two radiation oncologists prospectively delineated GTVs of 24 patients on simul-CT (CT$_{GTV}$), T2-weighted MR (T2$_{GTV}$), echo planar b1000 DWI (DWI$_{GTV}$) and PET-CT (PET$_{GTV}$). Observers' agreement was assessed using Dice index. Kruskal-Wallis test assessed differences between methods. RESULTS Mean CT$_{GTV}$, T2$_{GTV}$, DWI$_{GTV}$, and PET$_{GTV}$ were 41.3±26.9 cc, 25.9±15.2 cc, 21±14.8 cc, and 37.7±27.7 cc for the first observer, and 42.2±27.9 cc, 27.6±16.9 cc, 19.9±14.9cc, and 34.8±24.3 cc for the second observer, respectively. Mean Dice index was 0.85 for CT$_{GTV}$, 0.84 for T2$_{GTV}$, 0.82 for DWI$_{GTV}$, and 0.89 for PET$_{GTV}$, representative of almost perfect agreement. Kruskal-Wallis test showed a statistically significant difference between methods (p=0.009). Dunn test showed there were differences between DWI$_{GTV}$ vs. PET$_{GTV}$ (p=0.040) and DWI$_{GTV}$ vs. CT$_{GTV}$ (p=0.008). CONCLUSION DWI resulted in smaller volume delineation compared to CT, T2-MR, and PET-CT functional images. Almost perfect agreements were reported for each imaging modality between two observers. DWI-MR seems to remain the optimal strategy for boost volume delineation for dose escalation in patients with LARC

Organic electronics allows the photo-electric excitation of neuronal activity in primary neuronal cultures and acute retinal explants

Interfacing organic electronics and biology offers new possibilities in biotechnology, due to the unique properties exhibited by organic conducting polymers (e.g. biological affinity, mechanical flexibility, ease of functionalization and cost effectiveness). Organic conducting polymers have been exploited as materials for cellular interfaces in several fashions as: (i) passive electrode coatings or culturing substrates, (ii) organic biosensors or (iii) actuators for neurotransmitter release and electrodes for controlled cell seeding, growth and activity detection. Very recently, an organic photovoltaic donor-acceptor blend has been exploited for neuron stimulation by a photo-electric process. With respect to previous examples with inorganic semiconductors, this system has several advantages including flexibility, no power requirement and biocompatibility. Here, we report the novel use of a single component semiconductor organic polymer for the direct control of neuronal activity. This interface, that is more efficient than the classical bulk hetero-junction interface, has the remarkable capability to evoke neuronal firing in response to illumination. We demonstrate that the polymer layer has the ability to induce action potential firing up to 20 Hz in cultured hippocampal neurons. Moreover, this interface has been exploited to restore visual response in retinal explants obtained from animal models of retinal degeneration (light-blinded albino SD rats). By recording local field potentials in the RGC layer, we demonstrated the ability of the organic conductive polymer to mimic the function of photoreceptors and induce retinal activation of retinal ganglion cells after light illumination. These results paved the way to the development of a new and disruptive technology for interfacing artificial devices with neuronal networks, with applications in neuroprosthesis and brain machine interface research