Metabolic fate of extracellular NAD in human skin fibroblasts

Extracellular NAD is degraded to pyridine and purine metabolites by different types of surface-located enzymes which are expressed differently on the plasmamembrane of various human cells and tissues. In a previous report, we demonstrated that NAD-glycohydrolase, nucleotide pyrophosphatase and 5'-nucleotidase are located on the outer surface of human skin fibroblasts. Nucleotide pyrophosphatase cleaves NAD to nicotinamide mononucleotide and AMP, and 5'-nucleotidase hydrolyses AMP to adenosine. Cells incubated with NAD, produce nicotinamide, nicotinamide mononucleotide, hypoxanthine and adenine. The absence of ADPribose and adenosine in the extracellular compartment could be due to further catabolism and/or uptake of these products. To clarify the fate of the purine moiety of exogenous NAD, we investigated uptake of the products of NAD hydrolysis using U-[(14)C]-adenine-NAD. ATP was found to be the main labeled intracellular product of exogenous NAD catabolism; ADP, AMP, inosine and adenosine were also detected but in small quantities. Addition of ADPribose or adenosine to the incubation medium decreased uptake of radioactive purine, which, on the contrary, was unaffected by addition of inosine. ADPribose strongly inhibited the activity of ecto-NAD-hydrolyzing enzymes, whereas adenosine did not. Radioactive uptake by purine drastically dropped in fibroblasts incubated with (14)C-NAD and dipyridamole, an inhibitor of adenosine transport. Partial inhibition of [(14)C]-NAD uptake observed in fibroblasts depleted of ATP showed that the transport system requires ATP to some extent. All these findings suggest that adenosine is the purine form taken up by cells, and this hypothesis was confirmed incubating cultured fibroblasts with (14)C-adenosine and analyzing nucleoside uptake and intracellular metabolism under different experimental conditions. Fibroblasts incubated with [(14)C]-adenosine yield the same radioactive products as with [(14)C]-NAD; the absence of inhibition of [(14)C]-adenosine uptake by ADPribose in the presence of alpha-beta methyleneADP, an inhibitor of 5' nucleotidase, demonstrates that ADPribose coming from NAD via NAD-glycohydrolase is finally catabolised to adenosine. These results confirm that adenosine is the NAD hydrolysis product incorporated by cells and further metabolized to ATP, and that adenosine transport is partially ATP dependent

Quantitative and Qualitative Assessments of Retinal Structure with Variable A-Scan Rate Spectralis OCT: Insights into IPL Multilaminarity

The aim of this study was to evaluate the qualitative and quantitative differences between 20 and 85 kHz A-scan rate optical coherence tomography (OCT) images acquired by spectral domain OCT. The study included 60 healthy subjects analyzed with horizontal linear scans with a variable A-scan rate (SHIFT technology, Heidelberg Engineering, Heidelberg, Germany). The retinal thickness measurement of each retinal layer was performed in three different positions (subfoveal, nasal, and temporal). The qualitative assessment was performed by two independent observers who rated every image with a score ranging from 1 ("sufficient") to 3 ("excellent") on the basis of three parameters: visualization of the vitreo-retinal interface, characterization of the retinal layers, and visualization of the sclero-choroidal interface. No statistically significant differences in terms of retinal layer thickness between the two A-scan rate scans were observed (p > 0.05). The coefficient of variation of the retinal thickness values was lower in the 20 kHz group (25.8% versus 30.1% with the 85 kHz). The 20 kHz images showed a higher quality index for both observers. An inner plexiform layer (IPL) multilaminarity was detected in 78.3% of patients from the 20 kHz group and in 40% of patients from the 85 kHz group (p < 0.05)

Prevalence of mutations in LEP, LEPR, and MC4R genes in individuals with severe obesity

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The management of pediatric severe traumatic brain injury: Italian guidelines

Introduction: the aim of the work was to update the “guidelines for the Management of severe traumatic Brain Injury” published in 2012, to reflect the new available evidence, and develop the Italian national guideline for the management of severe pediatric head injuries to reduce variation in practice and ensure optimal care to patients. eViDeNce acQUisitioN: MeDliNe and eMBase were searched from January 2009 to october 2017. inclusion criteria were english language, pediatric populations (0-18 years) or mixed populations (pediatric/adult) with available age subgroup analyses. the guideline development process was started by the Promoting group that composed a multidisciplinary panel of experts, with the representatives of the Scientific Societies, the independent expert specialists and a representative of the Patient associations. the panel selected the clinical questions, discussed the evidence and formulated the text of the recommendations. the documentarists of the University of Florence oversaw the bibliographic research strategy. a group of literature reviewers evaluated the selected literature and compiled the table of evidence for each clinical question. EVIDENCE SYNTHESIS: The search strategies identified 4254 articles. We selected 3227 abstract (first screening) and, finally included 67 articles (second screening) to update the guideline. This Italian update includes 25 evidence-based recommendations and 5 research recommendations. coNclUsioNs: in recent years, progress has been made on the understanding of severe pediatric brain injury, as well as on that concerning all major traumatic pathology. this has led to a progressive improvement in the clinical outcome, although the quantity and quality of evidence remains particularly low

Consensus statement from the international consensus meeting on post-traumatic cranioplasty

Abstract: Background: Due to the lack of high-quality evidence which has hindered the development of evidence-based guidelines, there is a need to provide general guidance on cranioplasty (CP) following traumatic brain injury (TBI), as well as identify areas of ongoing uncertainty via a consensus-based approach. Methods: The international consensus meeting on post-traumatic CP was held during the International Conference on Recent Advances in Neurotraumatology (ICRAN), in Naples, Italy, in June 2018. This meeting was endorsed by the Neurotrauma Committee of the World Federation of Neurosurgical Societies (WFNS), the NIHR Global Health Research Group on Neurotrauma, and several other neurotrauma organizations. Discussions and voting were organized around 5 pre-specified themes: (1) indications and technique, (2) materials, (3) timing, (4) hydrocephalus, and (5) paediatric CP. Results: The participants discussed published evidence on each topic and proposed consensus statements, which were subject to ratification using anonymous real-time voting. Statements required an agreement threshold of more than 70% for inclusion in the final recommendations. Conclusions: This document is the first set of practical consensus-based clinical recommendations on post-traumatic CP, focusing on timing, materials, complications, and surgical procedures. Future research directions are also presented

Enzymatic activities affecting exogenous nicotinamide adenine dinucleotide in human skin fibroblasts

The fate of nicotinamide adenine dinucleotide (NAD), AMP, and ADP-ribose supplied to intact human skin fibroblasts was monitored, and the concentrations of intra- and extracellular pyridine and purine compounds were determined by HPLC analysis. Two enzymatic activities affecting extracellular NAD were detected on the plasma membrane, one hydrolyzing the pyrophosphoric bond and yielding nicotinamide mononucleotide (nucleotide pyrophosphatase) and the other cleaving the glycoside link and releasing nicotinamide (NAD-glycohydrolase). No AMP or ADP-ribose was found in the extracellular medium of cells incubated with NAD, the former being completely catabolized to hypoxanthine and the latter degraded to adenine and hypoxanthine

PARP activity and NAD concentration in PMC from patients affected by systemic sclerosis and lupus erythematosus

The enzyme poly(ADP-ribose) polymerase (PARP-1, EC 2.4.2.30) is activated by DNA strand breaks caused by several agents and utilizes NAD to form polyADPR, bound to acceptor proteins. The involvement of PARP-1 in autoimmune diseases has been suggested: antiPARP autoantibodies are described in systemic lupus erythematosus (SLE), DNA strand breaks have been evidenced in systemic sclerosis (SSc). We tested poly(ADP-ribosyl)ation activity and NAD concentration in PMC from patients affected by SLE or SSc and from controls. Lower PARP-1 activity and higher NAD concentration were observed in pathological conditions than controls, supporting the role of PARP-1 activation in modulating NAD concentration