Reactions of HNO with Metal Porphyrins: Underscoring the Biological Relevance of HNO

Azanone (1 HNO, nitroxyl) shows interesting yet poorly understood chemical and biological effects. HNO has some overlapping properties with nitric oxide (NO), sharing its biological reactivity toward heme proteins, thiols, and oxygen. Despite this similarity, HNO and NO show significantly different pharmacological effects. The high reactivity of HNO means that studies must rely on the use of donor molecules such as trioxodinitrate (Angeli’s salt). It has been suggested that azanone could be an intermediate in several reactions and that it may be an enzymatically produced signaling molecule. The inherent difficulty in detecting its presence unequivocally prevents evidence from yielding definite answers. On the other hand, metalloporphyrins are widely used as chemical models of heme proteins, providing us with invaluable tools for the study of the coordination chemistry of small molecules, like NO, CO, and O2. Studies with transition metal porphyrins have shown diverse mechanistic, kinetic, structural, and reactive aspects related to the formation of nitrosyl complexes. Porphyrins are also widely used in technical applications, especially when coupled to a surface, where they can be used as electrochemical gas sensors. Given their versatility, they have not escaped their role as key players in chemical studies involving HNO. This Account presents the research performed during the last 10 years in our group concerning azanone reactions with iron, manganese, and cobalt porphyrins. We begin by describing their HNO trapping capabilities, which result in formation of the corresponding nitrosyl complexes. Kinetic and mechanistic studies of these reactions show two alternative operating mechanisms: reaction of the metal center with HNO or with the donor. Moreover, we have also shown that azanone can be stabilized by coordination to iron porphyrins using electron-attracting substituents attached to the porphyrin ring, which balance the negatively charged NO¯. Second, we describe an electrochemical HNO sensing device based on the covalent attachment of a cobalt porphyrin to gold. A surface effect affects the redox potentials and allows discrimination between HNO and NO. The reaction with the former is fast, efficient, and selective, lacking spurious signals due to the presence of reactive nitrogen and oxygen species. The sensor is both biologically compatible and highly sensitive (nanomolar). This time-resolved detection allows kinetic analysis of reactions producing HNO. The sensor thus offers excellent opportunities to be used in experiments looking for HNO. As examples, we present studies concerning (a) HNO donation capabilities of new HNO donors as assessed by the sensor, (b) HNO detection as an intermediate in O atom abstraction to nitrite by phosphines, and (c) NO to HNO interconversion mediated by alcohols and thiols. Finally, we briefly discuss the key experiments required to demonstrate endogenous HNO formation to be done in the near future, involving the in vivo use of the HNO sensing device.Fil: Doctorovich, Fabio. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Química, Física de los Materiales, Medioambiente y Energía. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Química, Física de los Materiales, Medioambiente y Energía; ArgentinaFil: Bikiel, Damian Ezequiel. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Química, Física de los Materiales, Medioambiente y Energía. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Química, Física de los Materiales, Medioambiente y Energía; ArgentinaFil: Pellegrino, Juan. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Química, Física de los Materiales, Medioambiente y Energía. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Química, Física de los Materiales, Medioambiente y Energía; ArgentinaFil: Suarez, Sebastian. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Química, Física de los Materiales, Medioambiente y Energía. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Química, Física de los Materiales, Medioambiente y Energía; ArgentinaFil: Marti, Marcelo Adrian. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Química, Física de los Materiales, Medioambiente y Energía. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Química, Física de los Materiales, Medioambiente y Energía; Argentin

Towards practical quantum position verification

We discuss protocols for quantum position verification schemes based on the standard quantum cryptographic assumption that a tagging device can keep classical data secure [Kent, 2011]. Our schemes use a classical key replenished by quantum key distribution. The position verification requires no quantum communication or quantum information processing. The security of classical data makes the schemes secure against non-local spoofing attacks that apply to schemes that do not use secure tags. The schemes are practical with current technology and allow for errors and losses. We describe how a proof-of-principle demonstration might be carried out

Unusual signals in a halo catheter: what is the mechanism?

In this "featured arrhythmia" article we present a set of unusual intracardiac electrode tracings that were recorded in a patient with typical clockwise flutter but a very dilated right atrium. The potential mechanism underlying this phenomenon is discussed with reference to the current literature

Countering avoidance strategies used by fishers to avoid detection during illegal fishing

Non-compliers typically avoid detection by authorities, benefiting from increased catch and income. While detection-avoidance strategies (e.g., secret compartments to hide illegal catch) are commonly used in the nature conservation context, they remain largely unstudied. We address this knowledge gap in three sections. First, we introduce and hypothesize the likelihood of non-compliers adopting detection-avoidance strategies in the broader conservation context. Second, we identify and categorize detection-avoidance strategies used by small-scale fishers. Third, we provide recommendations for countering detection-avoidance strategies (i.e., countermeasures). Because countermeasures are context-specific, they should be informed through systematic processes such as the intelligence cycle. If used properly, enforcement activities and countermeasures can help build voluntary compliance, particularly through procedural justice, or acting in a way that users perceive as fair and just

Removal of necrotic alveolar part of mandible with CGF (Concentrated Growth Factors) application into a post-operative bone defect – a case report

Usage of platelet concentrate is an interesting clinical option for enhancement of healing tissue. One of them – Concentrated Growth Factors (CGF) is produced by processing blood samples with a special centrifuge device. It is proven that this material contains high concentration of growth factors and CD34+ cells which have anti-inflammatory properties and ability to stimulate proliferation and differentiation of connective tissue cells and angiogenesis. The following article presents a case of 70-year-old-patient who underwent the augmentation of the post-operative bone defect with CGF after removal of necrotic alveolar part of the mandible

Why use a mirror to assess visual pursuit in prolonged disorders of consciousness? Evidence from healthy control participants

Background: Evidence of reliable smooth visual pursuit is crucial for both diagnosis and prognosis in prolonged disorders of consciousness (PDOC). However, a mirror is more likely than an object to elicit evidence of smooth pursuit. Our objective was to identify the physiological and/or cognitive mechanism underlying the mirror benefit. Methods: We recorded eye-movements while healthy participants simultaneously completed a visual pursuit task and a cognitively demanding two-back task. We manipulated the stimulus to be pursued (two levels: mirror, ball) and the simultaneous cognitive load (pursuit only, pursuit plus two-back task) within subjects. Results: Pursuit of the reflected-own-face in the mirror was associated with briefer fixations that occurred less uniformly across the horizontal plane relative to object pursuit. Secondary task performance did not differ between pursuit stimuli. The secondary task also did not affect eye movement measures, nor did it interact with pursuit stimulus. Conclusions: Reflected-own-face pursuit is no less cognitively demanding than object pursuit, but it naturally elicits smoother eye movements (i.e. briefer pauses to fixate). A mirror therefore provides greater sensitivity to detect smooth visual pursuit in PDOC because the naturally smoother eye movements may be identified more confidently by the assessor

Locomotion behavior of dairy cows on traditional summer mountain farms in comparison with modern cubicle housing without access to pasture.

Pasture based systems enable cattle to express their natural behavior and are thus expected to provide better welfare than the majority of confinement systems. The aim of this study was to objectively measure locomotion activity of healthy dairy cattle kept on mountain pastures (n = 44) compared with cows kept in cubicle housing systems (n = 38). Selected cows were equipped with a validated 3D-accelerometer on one hind limb, and locomotion behavior was recorded for 48 hours. The 1-hour summaries of the variables lying time, walking time, standing bouts, walking bouts and number of strides were summed up to 24-hour summaries, and the means of the stride distance and stride duration were weighted by the variable number of strides. Mountain pasture cows had higher locomotor activity levels in comparison to cubicle cows. Mountain pasture cows spent less time lying down (528.1±109.5 min/day vs. 693.3±73.8 min/day; P<0.0001) and more time walking (75.6±25.9 min/day vs. 38.8±15.8 min/day; P <0.0001) than cubicle cows. Lying bout duration was longer in cubicle than in mountain pasture cows (90.9± 15.2 min/bout vs. 74.2 ± 21.1 min/bout; P = 0.0001), whilst the number of walking bouts was higher in mountain pasture cows than cubicle cows (199.1 ± 49.1 vs. 123.8 ± 43.8 bouts per day; P < 0.001). Likewise, the number of strides was higher in mountain pasture cows than cubicle cows (2040.5 ± 825.3 vs. 916.7 ± 408.6; P < 0.001). Mountain pasture cows had shorter stride duration (P < 0.0001) and shorter strides (P = 0.0002) than cubicle cows (1.8 ± 0.1 s/stride vs 2 ± 0.2 s/stride and 126.3 ± 18.1 vs 142.1 ± 17.8 m/stride, respectively). In summary, cows kept on mountain pasture were more active and spent longer than 12 hours / day standing. Lying markedly less than 12 hours per day seems to represent the normal behavior of pastured cows searching for fresh grass. This does not cause any obvious damage to the locomotor system as claws of cattle are well adapted to long periods of movement on mountain pastures

Quantum secret sharing with qudit graph states

We present a unified formalism for threshold quantum secret sharing using graph states of systems with prime dimension. We construct protocols for three varieties of secret sharing: with classical and quantum secrets shared between parties over both classical and quantum channels.Comment: 13 pages, 12 figures. v2: Corrected to reflect imperfections of (n,n) QQ protocol. Also changed notation from $(n,m)$ to $(k,n)$, corrected typos, updated references, shortened introduction. v3: Updated acknowledgement

Towards GPU Utilization Prediction for Cloud Deep Learning

Understanding the GPU utilization of Deep Learning (DL) workloads is important for enhancing resource-efficiency and cost-benefit decision making for DL frameworks in the cloud. Current approaches to determine DL workload GPU utilization rely on online profiling within isolated GPU devices, and must be performed for every unique DL workload submission resulting in resource under-utilization and reduced service availability. In this paper, we propose a prediction engine to proactively determine the GPU utilization of heterogeneous DL workloads without the need for in-depth or isolated online profiling. We demonstrate that it is possible to predict DL workload GPU utilization via extracting information from its model computation graph. Our experiments show that the prediction engine achieves an RMSLE of 0.154, and can be exploited by DL schedulers to achieve up to 61.5% improvement to GPU cluster utilization