scholarly journals Pulse-radiolysis studies on the interaction of one-electron reduced species with blue oxidases. Reduction of type-2-copper-depleted ascorbate oxidase

1984 ◽  
Vol 222 (1) ◽  
pp. 65-70 ◽  
Author(s):  
P O'Neill ◽  
E M Fielden ◽  
L Avigliano ◽  
G Marcozzi ◽  
A Ballini ◽  
...  
Keyword(s):  
Pulse Radiolysis ◽  
Ascorbate Oxidase ◽  
Native Protein ◽  
Rate Determining Step ◽  
Type 1 Copper ◽  
Intramolecular Transfer ◽  
Reducing Equivalents

The interaction of one-electron reduced metronidazole (ArNO2.-) with native and Type-2-copper-depleted ascorbate oxidase were studied in buffered aqueous solution at pH 6.0 and 7.4 by using the technique of pulse radiolysis. With ArNO2.-, reduction of Type 1 copper of the native enzyme and of the Type-2-copper-depleted ascorbate oxidase occurs via a bimolecular step and at the same rate. Whereas the native protein accepts, in the absence of O2, 6-7 reducing equivalents, Type-2-copper-depleted ascorbate oxidase accepts only 3 reducing equivalents with stoichiometric reduction of Type 1 copper. On reaction of O2.- with ascorbate oxidase under conditions of [O2.-] much greater than [ascorbate oxidase], removal of Type 2 copper results in reduction of all the Type 1 copper atoms, in contrast with reduction of the equivalent of only one Type 1 copper atom in the holoprotein. From observations at 610 nm, the rate of reduction of ascorbate oxidase by O2.- is not dependent on the presence of Type 2 copper. For the holoprotein, no significant optical-absorption changes were observed at 330 nm. It is proposed that electrons enter the protein via Type 1 copper in a rate-determining step followed by a fast intramolecular transfer of electrons within the protein. For the Type-2-copper-depleted protein, intramolecular transfer within the protein, however, is slow or does not occur. In the presence of O2, it is also suggested that re-oxidation of the partially reduced holoprotein occurs at steady state, as inferred from the observations at 330 nm and 610 nm. The role of Type 2 copper in ascorbate oxidase is discussed in terms of its involvement in redistribution of electrons within the protein or structural considerations.

scholarly journals Pulse-radiolysis studies on the interaction of one-electron-reduced species with ascorbate oxidase in aqueous solution

1983 ◽  
Vol 209 (1) ◽  
pp. 167-174 ◽  
Author(s):  
P O'Neill ◽  
E M Fielden ◽  
A Finazzi-Agrò ◽  
L Avigliano
Keyword(s):  
Aqueous Solution ◽  
Pulse Radiolysis ◽  
Ascorbate Oxidase ◽  
Intramolecular Electron Transfer ◽  
Protein Residues ◽  
Type 1 Copper ◽  
Type 3 ◽  
Reducing Equivalents

The interaction of e-aq., CO2-. and one-electron reduced nitroaromatics (RNO2-.) with ascorbate oxidase (AAO) was studied in aqueous solution at pH 6.0 and 7.5 by using the technique of pulse radiolysis. From observations at 330, 410 and 610 nm, interaction of e-aq. and CO2-. with AAO results in non-specific reduction of the protein followed by reduction of Type 1 Cu in a rate-determining intramolecular step. Only a few per cent of the reducing equivalents ultimately results in reduction of Type 1 Cu. With large excesses of reducing equivalents (e-aq. and CO2-.) with respect to the copper concentration, the amount of Type 1 copper reduced never exceeds 50% of the total amount of Type 1 copper after a single radiation pulse. With less-powerful reducing agents, e.g. RNO2-. reduction of Type 1 Cu occurs via a bimolecular step, and there is no evidence for formation of radicals on protein residues. From observations at 330 nm it is evident that Type 2 and/or Type 3 Cu may also be reduced along with Type 1 Cu. Almost stoichiometric reduction of AAO by RNO2-. was observed, e.g. the protein accepts 6-7 reducing equivalents. It is inferred that the various types of redox couples Cu2+/Cu+ are in equilibrium and that intramolecular electron transfer between the different types of Cu is not rate-determining when using RNO2-. as reducing agent.

scholarly journals Pulse-radiolysis studies on the interaction of one-electron reduced species with blue oxidases. Reduction of native and type-2-copper-depleted Vietnamese-lacquer-tree and Japanese-lacquer-tree laccases

1984 ◽  
Vol 222 (1) ◽  
pp. 71-76 ◽  
Author(s):  
P O'Neill ◽  
E M Fielden ◽  
L Morpurgo ◽  
E Agostinelli
Keyword(s):  
Pulse Radiolysis ◽  
Electron Donors ◽  
Catalytic Activities ◽  
Molecular Electron ◽  
Reducing Equivalent ◽  
Type 1 Copper ◽  
Type 3 ◽  
Intramolecular Transfer

The interactions of one-electron reduced metronidazole (ArNO2.-) and O2.- with native and Type-2-copper-depleted Vietnamese- and Japanese-lacquer-tree laccases were studied in aqueous solution at pH 6.0 and 7.4 by using the technique of pulse radiolysis. On reaction with ArNO2.-, in the absence of O2, the holo- and the Type-2-copper-depleted proteins accept, with reduction of Type 1 copper, 2 and 1 reducing equivalents respectively. On reaction with O2.- of both holo- and Type-2-copper-depleted Vietnamese-lacquer-tree laccase, almost complete reduction of Type 1 copper was observed and, after completion of the reaction, some (less than 20%) reoxidation of Type 1 copper occurs. Reduction of Type 1 copper of the laccases by these one-electron donors occurs via a bimolecular step; however, the rate of reduction of Vietnamese-lacquer-tree laccase is over 10 times that of Japanese-lacquer-tree laccase. It is inferred that electrons enter the protein via Type 1 copper with, in the case of the holoprotein, subsequent rapid intramolecular transfer of 1 reducing equivalent within the protein. Furthermore it is suggested that intra-molecular electron transfer to Type 3 copper atoms is slow and, in the case of Type-2-copper-depleted protein, may not occur. This slow process may partially account for the variation of the catalytic activities of ‘blue’ oxidases.

scholarly journals Role of Oral Antioxidant Supplementation in the Current Management of Diabetic Retinopathy

2021 ◽  
Vol 22 (8) ◽  
pp. 4020
Author(s):  
Enrique Antonio Alfonso-Muñoz ◽  
Raquel Burggraaf-Sánchez de las Matas ◽  
Jorge Mataix Boronat ◽  
Julio César Molina Martín ◽  
Carmen Desco
Keyword(s):  
Diabetic Retinopathy ◽  
Diabetic Macular Oedema ◽  
Complementary Therapy ◽  
Antioxidant Supplementation ◽  
Current Management ◽  
Adult Type ◽  
Aged People

Oxidative stress has been postulated as an underlying pathophysiologic mechanism of diabetic retinopathy (DR), the main cause of avoidable blindness in working-aged people. This review addressed the current daily clinical practice of DR and the role of antioxidants in this practice. A systematic review of the studies on antioxidant supplementation in DR patients was presented. Fifteen studies accomplished the inclusion criteria. The analysis of these studies concluded that antioxidant supplementation has a IIB level of recommendation in adult Type 1 and Type 2 diabetes mellitus subjects without retinopathy or mild-to-moderate nonproliferative DR without diabetic macular oedema as a complementary therapy together with standard medical care.

scholarly journals EXPRESS: Pulmonary Hypertension Associated With Neurofibromatosis Type 2

2021 ◽  
pp. 204589402110295
Author(s):  
Hirohisa Taniguchi ◽  
Tomoya Takashima ◽  
Ly Tu ◽  
Raphaël Thuillet ◽  
Asuka Furukawa ◽  
...  
Keyword(s):  
Pulmonary Hypertension ◽  
Neurofibromatosis Type ◽  
Pulmonary Vascular Remodeling ◽  
Life Threatening ◽  
History Of ◽  
Pulmonary Arterial ◽  
First Time

Although precapillary pulmonary hypertension (PH) is a rare but severe complication of patients with neurofibromatosis type 1 (NF1), its association with NF2 remains unknown. Herein, we report a case of a 44-year-old woman who was initially diagnosed with idiopathic pulmonary arterial hypertension (IPAH) and treated with PAH-specific combination therapy. However, a careful assessment for a relevant family history of the disease and genetic testing reveal that this patient had a mutation in the NF2 gene. Using immunofluorescence and Western blotting, we demonstrated a decrease in endothelial NF2 protein in lungs from IPAH patients compared to control lungs, suggesting a potential role of NF2 in PAH development. To our knowledge, this is the first time that precapillary PH has been described in a patient with NF2. The altered endothelial NF2 expression pattern in PAH lungs should stimulate work to better understand how NF2 is contributing to the pulmonary vascular remodeling associated to these severe life-threatening conditions.

The role of modifiable pre-pregnancy risk factors in preventing adverse fetal outcomes among women with type 1 and type 2 diabetes

2009 ◽  
Vol 88 (10) ◽  
pp. 1153-1157 ◽  
Author(s):  
Melanie E. Inkster ◽  
Tom P. Fahey ◽  
Peter T. Donnan ◽  
Graham P. Leese ◽  
Gary J. Mires ◽  
...  
Keyword(s):  
Risk Factors ◽  
Type 2 Diabetes ◽  
Fetal Outcomes ◽  
Pregnancy Risk

Keratoprostheses in silicone oil-filled eyes: long-term outcomes

2018 ◽  
Vol 103 (6) ◽  
pp. 781-788 ◽  
Author(s):  
Geetha Iyer ◽  
Bhaskar Srinivasan ◽  
Shweta Agarwal ◽  
Ruchika Pattanaik ◽  
Ekta Rishi ◽  
...  
Keyword(s):  
Silicone Oil ◽  
Vitreoretinal Surgery ◽  
Retrospective Chart Review ◽  
Protective Role ◽  
Visual Rehabilitation ◽  
Two Factors

PurposeTo analyse the functional and anatomical outcomes of different types of keratoprostheses in eyes with retained silicone oil following vitreoretinal surgery.MethodsRetrospective chart review of patients operated with any type of permanent keratoprosthesis (Kpro) in silicone oil-filled eyes between March 2003 and June 2017 were analysed.Results40 silicone oil-filled eyes underwent keratoprostheses, of which 22 were type 1 and 18 were type 2 Kpros (Lucia variant—nine, modified osteo odonto kerato prosthesis (MOOKP)—four, Boston type 2—three and osteoKpro—two) with a mean follow-up of 61.54 , 42.77, 45.25 , 25 and 37 months, respectively. Anatomic retention of the primary Kpro was noted in 33 eyes (82.5%). A best-corrected visual acuity of better than 20/200 and 20/400 was achieved in 26 (65%)+32 (80%) eyes. Retroprosthetic membrane (RPM) was the most common complication noted in 17 eyes (42.5%). Perioptic graft melt was noted in 4 of 22 eyes of the type 1 Kpro (2 (10.5%) without associated ocular surface disorder (OSD)) and in 1 eye each of Boston and Lucia type 2 Kpro. Laminar resorption occurred in one eye each of the MOOKP and OKP groups. Endophthalmitis and glaucoma did not occur in any eye.ConclusionAppropriately chosen keratoprosthesis is a viable option for visual rehabilitation in eyes post vitreoretinal surgery with retained silicone oil-induced keratopathy not amenable to conventional penetrating keratoplasty. Kpro melt among type 1 Kpro did not occur in 89.5% eyes without associated OSD (19 of 22 eyes), despite the lack of aqueous humour and presence of RPM (4 eyes), two factors considered to play a significant role in the causation of sterile melts. Of interest to note was the absence of infection in any of these eyes. The possible protective role of oil from endophthalmitis is interesting, though yet to be ascertained.

scholarly journals The role of selected mechanisms of innate immunity in the pathogenesis of diabetes

2021 ◽  
Vol 11 (9) ◽  
pp. 544-549
Author(s):  
Paulina Trojanowska ◽  
Magdalena Chrościńska-Krawczyk ◽  
Alina Trojanowska ◽  
Ewa Tywanek ◽  
Jakub Wronecki ◽  
...  
Keyword(s):  
Innate Immunity ◽  
Metabolic Diseases ◽  
Inflammatory Diseases ◽  
The Body ◽  
Low Grade ◽  
Intracellular Space ◽  
Cytoplasmic Proteins

Understanding the important role of the non-specific immune response in protecting the body against the development of numerous diseases has become partially possible after the discovery of several classes of pattern recognition receptors (PRR), such as Toll-like or NOD-like receptors. A group of cytoplasmic proteins called the inflammasome, which detect PAMP and DAMP through the PRR receptors, is able to activate pro-inflammatory cytokines and trigger an acute inflammatory reaction both in the extracellular and intracellular space. Low-grade systemic and local inflammation contributes to the development and progression of various conditions, including autoimmune and metabolic diseases, such as diabetes, metabolic syndrome and atherosclerosis, which until recently were not even considered inflammatory diseases. This review will discuss the role of innate immunity in the development of type 1 and type 2 diabetes, focusing on the role of specific innate immunity receptors and insulin resistance involved in these diseases pathogenesis.

scholarly journals Role of a registered dietitian in pediatric type 1 and type 2 diabetes

2017 ◽  
Vol 6 (4) ◽  
pp. 365-372 ◽  
Author(s):  
Tracie J. Steinke ◽  
Elena L. O’Callahan ◽  
Jennifer L. York
Keyword(s):  
Type 2 Diabetes ◽  
Registered Dietitian
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