Formation of nitric oxide from nitroxyl anion: role of quinones and ferricytochrome c

1. Our previous finding that copper ions oxidize nitroxyl anion released from Angeli's salt to nitric oxide prompted us to examine if copper-containing enzymes shared this property. 2. The copper-containing enzyme, tyrosinase, which catalyses the hydroxylation of monophenols to diphenols and the subsequent oxidation of these to the respective unstable quinone, failed to generate nitric oxide from Angeli's salt by itself, but did so in the presence of tyrosine. 3. L-DOPA, the initial product of the reaction of tyrosinase with tyrosine, was not the active species, since it failed to generate nitric oxide from Angeli's salt. Nevertheless, L-DOPA and two other substrates, namely, catechol and tyramine did produce nitric oxide from Angeli's salt in the presence of tyrosinase, suggesting involvement of the respective unstable quinones. In support, we found that 1,4-benzoquinone produced a powerful nitric oxide signal from Angeli's salt. 4. Coenzyme Q(o), an analogue of ubiquinone, failed to generate nitric oxide from Angeli's salt by itself, but produced a powerful signal in the presence of its mitochondrial complex III cofactor, ferricytochrome c. 5. Experiments conducted on rat aortic rings with the mitochondrial complex III inhibitor, myxothiazol, to determine if this pathway was responsible for the vascular conversion of nitroxyl to nitric oxide were equivocal: relaxation to Angeli's salt was inhibited but so too was that to unrelated relaxants. 6. Thus, certain quinones oxidize nitroxyl to nitric oxide. Further work is required to determine if endogenous quinones contribute to the relaxant actions of nitroxyl donors such as Angeli's salt.     

Role of copper ions and cytochrome P450 in the vasodilator actions of the nitroxyl anion generator, Angeli's salt, on rat aorta

Since copper ions catalyse the oxidation of nitroxyl anion to nitric oxide, we investigated whether this might explain the vasodilator actions of the nitroxyl generator, Angeli's salt, in rat aorta. Parallel studies were conducted with S-nitroso-N-acetyl-D,L-penicillamine (SNAP), since Cu ions catalyse the liberation of nitric oxide from this compound. Copper sulphate enhanced relaxation to Angeli's salt and SNAP but this resulted from reduced destruction of nitric oxide by superoxide rather than from enhanced generation of nitric oxide, since it was mimicked by superoxide dismutase and by the superoxide dismutase mimetic, MnCl2. Results with the selective Cu2+ chelators, neocuproine and bathocuproine disulfonate, and the Cu2+ chelators, EDTA, cuprizone and diethyldithiocarbamate, confirmed an important role for endogenous copper in mediating relaxation to SNAP but suggested only a minor role for Angeli's salt. Relaxation to Angeli's salt was, however, powerfully blocked by proadifen, suggesting an important role for cytochrome P450.     

C5a anaphylatoxin is a major regulator of activating versus inhibitory FcgammaRs in immune complex-induced lung disease

IgG Fc receptors (FcgammaRs, especially FcgammaRIII) and complement (in particular, C5a anaphylatoxin) are critical effectors of the acute inflammatory response to immune complexes (ICs). However, it is unknown whether and how these two key components can interact with each other in vivo. We use here a mouse model of the acute pulmonary IC hypersensitivity reaction to analyze their potential interaction. FcgammaRIII and C5aR are coexpressed on alveolar macrophages (AMs), and both FcgammaRIII and C5aR mutant mice display impaired immune responses. We find that recombinant human C5a (rhC5a) can control inverse expression of various FcgammaRs, and costimulation of ICs with rhC5a results in strong enhancement of FcgammaRIII-triggered cellular activation in vitro and in vivo. Moreover, we show here that early IC-induced bioactive C5a, and its interaction with C5aR, causes induction of activating FcgammaRIII and suppression of inhibitory FcgammaRII on AMs that appears crucial for efficient cytokine production and neutrophil recruitment in lung pathology. Therefore, C5a, which is a potent chemoattractant, has a broader critical function in regulating the inhibitory/activating FcgammaRII/III receptor pair to connect complement and FcgammaR effector pathways in immune inflammation.     

Gender Differences in the Relationship between Depressive Symptoms and Cravings in Alcoholism

This study examines the clinical correlates of alcohol craving in men and women self‐referred for addiction treatment. Admission clinical data from patients participating in the Mayo Clinic 1‐month Intensive Addictions Program were evaluated. Women had higher BDI and PACS scores compared with men in both the entire cohort and Dual Diagnoses group. Alcohol‐dependent females had the most marked correlation between BDI and PACS (ρ= .78). Further prospective study is encouraged to evaluate whether depressive symptoms and concomitant alcohol cravings in women are a marker for relief cravings and, as such, a target symptom for treatment intervention. (Am J Addict 2010;00:1–5)     

Socioeconomic Status and Psychosocial Mechanisms of Lifestyle Change in a Type 2 Diabetes Prevention Trial

Background  

Little is known about psychosocial mechanisms that may underlie differences in lifestyle change between socioeconomic groups.     

The HIV prevention needs of injection drug users in Estonia

To assess the relationships between HIV transmission risk behaviours, HIV serostatus and knowledge of HIV serostatus among active injection drug users (IDUs) residing in Tallinn, Estonia, we conducted HIV testing and administered a standardized interview to 266 participants reporting recent injection drug use. In total, 45% were HIV positive, and of those, 39% knew their HIV serostatus. Those who knew their HIV-positive serostatus were less likely to report giving someone else their needle after they used it (9%) than were HIV-negative participants (23%) and those who were HIV positive but unaware of their HIV-positive serostatus (25%). There were no statistically significant differences in unprotected sex or other drug use behaviours between the groups. Most participants reported that HIV can be transmitted through sharing needles (98%) and unprotected sexual activity (93%). Prevention needs of IDUs in this area include increasing the rates of HIV testing and implementing effective programmes to reduce sexual and drug use risk behaviours.     

The subcellular localization of TRPP2 modulates its function

TRPP2, also known as polycystin-2, is a calcium permeable nonselective cation channel that is mutated in autosomal dominant polycystic kidney disease but has also been implicated in the regulation of cardiac development, renal tubular differentiation, and left-to-right (L-R) axis determination. For obtaining further insight into how TRPP2 exerts tissue-specific functions, this study took advantage of PACS-dependent trafficking of TRPP2 in zebrafish larvae. PACS proteins recognize an acidic cluster within the carboxy-terminal domain of TRPP2 that undergoes phosphorylation and mediate retrieval of TRPP2 to the Golgi and endoplasmic reticulum (ER). The interaction of human TRPP2 with PACS proteins can be inhibited by a Ser812Ala mutation (TRPP2(S812A)), thereby allowing TRPP2 to reach other subcellular compartments, and enhanced by a Ser812Asp mutation (TRPP2(S812D)), thereby trapping TRPP2 in the ER. It was found that the TRPP2(S812A) mutant rescued cyst formation of TRPP2-deficient zebrafish larvae to the same degree as wild-type TRPP2, whereas the TRPP2(S812D) mutant was significantly more effective in normalizing the distorted body axis of TRPP2-deficient fish. Surprisingly, the TRPP2(S812D) mutant rescued the abnormalities of L-R asymmetry more effectively than either wild-type or TRPP2(S812A), suggesting that the ER localization of TRPP2 plays an important role in the development of normal L-R asymmetry. Taken together, these findings support the hypothesis that TRPP2 assumes distinct subcellular localizations to exert tissue-specific functions.     

Complement 5a receptor inhibition improves renal allograft survival

Complement activation plays a key role in mediating apoptosis, inflammation, and transplant rejection. In this study, the role of the complement 5a receptor (C5aR) was examined in human renal allografts and in an allogenic mouse model of renal transplant rejection. In human kidney transplants with acute rejection, C5aR expression was increased in renal tissue and in cells infiltrating the tubulointerstitium. Similar findings were observed in mice. When recipient mice were treated once daily with a C5aR antagonist before transplantation, long-term renal allograft survival was markedly improved compared with vehicle-treatment (75 versus 0%), and apoptosis was reduced. Furthermore, treatment with a C5aR antagonist significantly attenuated monocyte/macrophage infiltration, perhaps a result of reduced levels of monocyte chemoattractant protein 1 and the intercellular adhesion molecule 1. In vitro, C5aR antagonism inhibited intercellular adhesion molecule 1 upregulation in primary mouse aortic endothelial cells and reduced adhesion of peripheral blood mononuclear cells. Furthermore, C5aR blockade markedly reduced alloreactive T cell priming. These results demonstrate that C5aR plays an important role in mediating acute kidney allograft rejection, suggesting that pharmaceutical targeting of C5aR may have potential in transplantation medicine.     

Induction therapy with paclitaxel and carboplatin followed by hyperfractionated radiotherapy plus weekly concurrent chemotherapy and subsequent consolidation therapy in unresectable locally advanced non-small-cell lung cancer

AIMS AND BACKGROUND: The purpose of this pilot study was to determine the safety and feasibility of a complete integrated approach, including induction chemotherapy with carboplatin/paclitaxel followed by accelerated hyperfractionated radiotherapy with concurrent chemotherapy, and then by consolidation chemotherapy for locally advanced stage III non-small cell lung carcinoma. METHODS: Systemic doses of carboplatin AUC 6 and paclitaxel (200 mg/m2), 3 weeks out of 4, were planned as induction and consolidation chemotherapy. Weekly carboplatin AUC of 2 plus paclitaxel (50 mg/m2) were given during thoracic radiotherapy. RESULTS: Eighteen patients were enrolled: 10 were evaluated at the end of chemoradiation and 8 received consolidation chemotherapy. On an intent-to-treat basis, 55% of patients achieved a response after induction therapy, whereas chemoradiation and consolidation therapy increased the response rate by 33% and 16%, respectively. No patient experienced grade > 3 acute hematologic toxicity during systemic-dose chemotherapy. With the exception of one episode of a severe cardiac adverse event, non-hematologic toxicity was similarly tolerable. Severe acute adverse events observed during concurrent chemoradiation were mainly represented by esophagitis, resulting in interruption of the radiotherapy in 25% of patients. More notably, only one patient experienced serious non-hematologic late toxicity. CONCLUSIONS: Although the present approach seemed feasible, our data did not support any possible advantage in favor of this three-phase integrated treatment, and therefore the design will not be investigated in a subsequent phase II study.