Hydrogen Sulfide, a Toxic Gas with Cardiovascular Properties in Uremia: How Harmful Is It?

Hydrogen sulfide (H2S) is a poisonous gas which can be lethal. However, it is also produced endogenously, thus belonging to the family of gasotransmitters along with nitric oxide and carbon monoxide. H2S is in fact involved in mediating several signaling and cytoprotective functions, for example in the nervous, cardiovascular, and gastrointestinal systems, such as neuronal transmission, blood pressure regulation and insulin release, among others. When increased, it can mediate inflammation and apoptosis, with a role in shock. When decreased, it can be involved in atherosclerosis, hypertension, myocardial infarction, diabetes, sexual dysfunction, and gastric ulcer; it notably interacts with the other gaseous mediators. Cystathionine γ-lyase, cystathionine β-synthase, and 3-mercaptopyruvate sulfurtransferase are the principal enzymes involved in H2S production. We have recently studied H2S metabolism in the plasma of chronic hemodialysis patients and reported that its levels are significantly decreased. The plausible mechanism lies in the transcription inhibition of the cystathionine γ-lyase gene. The finding could be of importance considering that hypertension and high cardiovascular mortality are characteristic in these patients

Uremic Toxin Lanthionine Interferes with the Transsulfuration Pathway, Angiogenetic Signaling and Increases Intracellular Calcium

(1) The beneficial effects of hydrogen sulfide (H2S) on the cardiovascular and nervous system have recently been re-evaluated. It has been shown that lanthionine, a side product of H2S biosynthesis, previously used as a marker for H2S production, is dramatically increased in circulation in uremia, while H2S release is impaired. Thus, lanthionine could be classified as a novel uremic toxin. Our research was aimed at defining the mechanism(s) for lanthionine toxicity. (2) The effect of lanthionine on H2S release was tested by a novel lead acetate strip test (LAST) in EA.hy926 cell cultures. Effects of glutathione, as a redox agent, were assayed. Levels of sulfane sulfur were evaluated using the SSP4 probe and flow cytometry. Protein content and glutathionylation were analyzed by Western Blotting and immunoprecipitation, respectively. Gene expression and miRNA levels were assessed by qPCR. (3) We demonstrated that, in endothelial cells, lanthionine hampers H2S release; reduces protein content and glutathionylation of transsulfuration enzyme cystathionine--synthase; modifies the expression of miR-200c and miR-423; lowers expression of vascular endothelial growth factor VEGF; increases Ca2+ levels. (4) Lanthionine-induced alterations in cell cultures, which involve both sulfur amino acid metabolism and calcium homeostasis, are consistent with uremic dysfunctional characteristics and further support the uremic toxin role of this amino acid

Zoledronic acid in metastatic chondrosarcoma and advanced sacrum chordoma: two case reports

<p>Abstract</p> <p>Introduction</p> <p>Chondrosarcomas and chordomas are usually chemoresistant bone tumors and may have a poor prognosis when advanced. They are usually associated with worsening pain difficult to control.</p> <p>Patients and Methods</p> <p>Zoledronic acid was used in a 63-year-old man with metastatic chondrosarcoma and in a 66-year-old woman with a diagnosis of sacrum chordoma both reporting severe pain related to tumor.</p> <p>Results</p> <p>In the first case, zoledronic acid was able to maintain pain control despite disease progression following chemotherapy, in the other case, zoledronic acid only produced significant clinical benefit.</p> <p>Conclusion</p> <p>Control of pain associated with bone tumors such as chondrosarcoma and chondroma may significantly improve from use of zoledronic acid, independently from tumor response to other treatments. Evaluation on larger series are needed to confirm the clinical effect of this bisphosphonate on such tumors.</p

Protein Isoaspartate Methyltransferase Prevents Apoptosis Induced by Oxidative Stress in Endothelial Cells: Role of Bcl-Xl Deamidation and Methylation

BACKGROUND:Natural proteins undergo in vivo spontaneous post-biosynthetic deamidation of specific asparagine residues with isoaspartyl formation. Deamidated-isomerized molecules are both structurally and functionally altered. The enzyme isoaspartyl protein carboxyl-O-methyltransferase (PCMT; EC 2.1.1.77) has peculiar substrate specificity towards these deamidated proteins. It catalyzes methyl esterification of the free alpha-carboxyl group at the isoaspartyl site, thus initiating the repair of these abnormal proteins through the conversion of the isopeptide bond into a normal alpha-peptide bond. Deamidation occurs slowly during cellular and molecular aging, being accelerated by physical-chemical stresses brought to the living cells. Previous evidence supports a role of protein deamidation in the acquisition of susceptibility to apoptosis. Aim of this work was to shed a light on the role of PCMT in apoptosis clarifying the relevant mechanism(s). METHODOLOGY/PRINCIPAL FINDINGS:Endothelial cells transiently transfected with various constructs of PCMT, i.e. overexpressing wild type PCMT or negative dominants, were used to investigate the role of protein methylation during apoptosis induced by oxidative stress (H(2)O(2); 0.1-0.5 mM range). Results show that A) Cells overexpressing "wild type" human PCMT were resistant to apoptosis, whereas overexpression of antisense PCMT induces high sensitivity to apoptosis even at low H(2)O(2) concentrations. B) PCMT protective effect is specifically due to its methyltransferase activity rather than to any other non-enzymatic interactions. In fact negative dominants, overexpressing PCMT mutants devoid of catalytic activity do not prevent apoptosis. C) Cells transfected with antisense PCMT, or overexpressing a PCMT mutant, accumulate isoaspartyl-containing damaged proteins upon H(2)O(2) treatment. Proteomics allowed the identification of proteins, which are both PCMT substrates and apoptosis effectors, whose deamidation occurs under oxidative stress conditions leading to programmed cell death. These proteins, including Hsp70, Hsp90, actin, and Bcl-xL, are recognized and methylated by PCMT, according to the general repair mechanism of this methyltransferase. CONCLUSION/SIGNIFICANCE:Apoptosis can be modulated by "on/off" switch partitioning the amount of specific protein effectors, which are either in their active (native) or inactive (deamidated) molecular forms. Deamidated proteins can also be functionally restored through methylation. Bcl-xL provides a case for the role of PCMT in the maintenance of functional stability of this antiapoptotic protein

Homocysteinylated Albumin Promotes Increased Monocyte-Endothelial Cell Adhesion and Up-Regulation of MCP1, Hsp60 and ADAM17

RATIONALE:The cardiovascular risk factor homocysteine is mainly bound to proteins in human plasma, and it has been hypothesized that homocysteinylated proteins are important mediators of the toxic effects of hyperhomocysteinemia. It has been recently demonstrated that homocysteinylated proteins are elevated in hemodialysis patients, a high cardiovascular risk population, and that homocysteinylated albumin shows altered properties. OBJECTIVE:Aim of this work was to investigate the effects of homocysteinylated albumin - the circulating form of this amino acid, utilized at the concentration present in uremia - on monocyte adhesion to a human endothelial cell culture monolayer and the relevant molecular changes induced at both cell levels. METHODS AND RESULTS:Treated endothelial cells showed a significant increase in monocyte adhesion. Endothelial cells showed after treatment a significant, specific and time-dependent increase in ICAM1 and VCAM1. Expression profiling and real time PCR, as well as protein analysis, showed an increase in the expression of genes encoding for chemokines/cytokines regulating the adhesion process and mediators of vascular remodeling (ADAM17, MCP1, and Hsp60). The mature form of ADAM17 was also increased as well as Tnf-α released in the cell medium. At monocyte level, treatment induced up-regulation of ICAM1, MCP1 and its receptor CCR2. CONCLUSIONS:Treatment with homocysteinylated albumin specifically increases monocyte adhesion to endothelial cells through up-regulation of effectors involved in vascular remodeling

MORFEO enters final design phase

MORFEO (Multi-conjugate adaptive Optics Relay For ELT Observations, formerly MAORY), the MCAO system for the ELT, will provide diffraction-limited optical quality to the large field camera MICADO. MORFEO has officially passed the Preliminary Design Review and it is entering the final design phase. We present the current status of the project, with a focus on the adaptive optics system aspects and expected milestones during the next project phase

The impact of the ketogenic diet on arterial morphology and endothelial function in children and young adults with epilepsy: a case-control study

The present study aimed to assess the impact of the ketogenic diet on arterial morphology and endothelial function of the big vessels of the neck and on cardiac diastolic function, in a cohort of epileptic children and young adults treated with the ketogenic diet

An AGT-based protein-tag system for the labelling and surface immobilization of enzymes on E. coli outer membrane

The use of natural systems, such as outer membrane protein A (OmpA), phosphoporin E (PhoE), ice nucleation protein (INP), etc., has been proved very useful for the surface exposure of proteins on the outer membrane of Gram-negative bacteria. These strategies have the clear advantage of unifying in a one-step the production, the purification and the in vivo immobilisation of proteins/biocatalysts onto a specific biological support. Here, we introduce the novel Anchoring-and-Self-Labelling-protein-tag (ASLtag), which allows the in vivo immobilisation of enzymes on E. coli surface and the labelling of the neosynthesised proteins with the engineered alkylguanine-DNA-alkyl-transferase (H5) from Sulfolobus solfataricus. Our results demonstrated that this tag enhanced the overexpression of thermostable enzymes, such as the carbonic anhydrase (SspCA) from Sulfurihydrogenibium yellowstonense and the β-glycoside hydrolase (SsβGly) from S. solfataricus, without affecting their folding and catalytic activity, proposing a new tool for the improvement in the utilisation of biocatalysts of biotechnological interest