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Three coagulase-negative staphylococci (CNS) species were investigated for gene expression of nitric oxide synthase (NOS) and the ability of nitrosomyoglobin (NO-Mb) formation in a dry sausage model without nitrite addition. The expression of nos gene was systematically proven from DNA to RNA to protein, and nitric oxide (NO) generation was also directly detected. In the dry sausage model system, the redness (a*-values) of samples inoculated with the three CNS species were higher than those inoculated with Pediococcus pentosaceus and the control (P < 0.05). The results from UV-vis and electron spin resonance spectroscopies revealed that pentacoordinate NO-Mb was formed in the sausages with either CNS or nitrite added. The sausage inoculated with Staphylococcus vitulinus had the highest NO-Mb content among the CNS-treated sausages. Dimer interface residues and phosphorylation sites of NOS in . itulinus differ from the other two CNS species as revealed by amino acid sequences, which may be responsible for the different catalytic activities., (Copyright © 2019 Elsevier Ltd. All rights reserved.)

Adaptive vascular remodeling in response to arterial occlusion takes the form of capillary growth (angiogenesis) and outward remodeling of pre-existing collateral arteries (arteriogenesis). However, the relative contributions of angiogenesis and arteriogenesis toward the overall reperfusion response are both highly debated and poorly understood. Here, we tested the hypothesis that myoglobin overexpressing transgenic mice (MbTg(+)) exhibit impaired angiogenesis in the setting of normal arteriogenesis in response to femoral artery ligation, and thereby serve as a model for disconnecting these two vascular growth processes. After femoral artery ligation, MbTg(+) mice were characterized by delayed distal limb reperfusion (by laser Doppler perfusion imaging), decreased foot use, and impaired distal limb muscle angiogenesis in both glycolytic and oxidative muscle fiber regions at day 7. Substantial arteriogenesis occurred in the primary collaterals supplying the ischemic limb in both wild-type and MbTg(+) mice; however, there were no significant differences between groups, indicating that myoglobin overexpression does not affect arteriogenesis. Together, these results uniquely demonstrate that functional collateral arteriogenesis alone is not necessarily sufficient for adequate reperfusion after arterial occlusion. Angiogenesis is a key component of an effective reperfusion response, and clinical strategies that target both angiogenesis and arteriogenesis could yield the most efficacious treatments for peripheral arterial disease., (Copyright © 2013 American Society for Investigative Pathology. Published by Elsevier Inc. All rights reserved.)

Staphylococcus xylosus and Pediococcus pentosaceus isolated from Chinese dried sausage were assessed for their ability to convert metmyoglobin into nitrosylmyoglobin in Mann-Rogosa-Sharp broth model systems and raw pork meat batters without the addition of nitrite. The results showed that samples in model systems with S. xylosus cultures had an absorption spectra that is typical of nitrosylmyoglobin, an obvious pink colour (judged by visual inspection) and a significantly higher a-value than the control samples or samples inoculated with P. pentosaceus. In raw meat batters, the a-values of the S. xylosus samples were almost the same as those for the meat with nitrite added. The complementary analysis of meat batter samples by photochemical information from UV-vis, electron spin resonance and resonance Raman spectroscopy revealed that the existing status of the myoglobin in meat batters inoculated with S. xylosus was mainly pentacoordinate nitrosylmyoglobin. This study provides a potential solution for nitrite substitute in meat products., (Copyright © 2012 Elsevier Ltd. All rights reserved.)

Glycation of horse heart metmyoglobin with d-ribose 5-phosphate (R5P), d-2-deoxyribose 5-phosphate (dR5P), and d-ribose with inorganic phosphate at 37°C generates an altered protein (Myo-X) with increased SDS-PAGE mobility. The novel protein product has been observed only for reactions with the protein myoglobin and it is not evident with other common sugars reacted over a 1 week period. Myo-X is first observed at 1-2 days at 37°C along with a second form that is consistent in mass with that of myoglobin attached to several sugars. MALDI mass spectrometry and other techniques show no evidence of the cleavage of a peptide from the myoglobin chain. Apomyoglobin in reaction with R5P also exhibited this protein form suggesting its occurrence was not heme-related. While significant amounts of O(2)(-) and H(2)O(2) are generated during the R5P glycation reaction, they do not appear to play roles in the formation of the new form. The modification is likely due to an internal cross-link formed during a glycation reaction involving the N-terminus and an internal amine group; most likely the neighboring Lys133. The study shows the unique nature of these common pentose sugars in spontaneous glycation reactions with proteins., (Copyright © 2011 Elsevier Inc. All rights reserved.)

Myoglobin is a multifunctional heme protein that is thought to be expressed exclusively in myocytes. Its importance in both oxygen transport and free radical scavenging has been extensively characterized. We hypothesized that solid tumors could take advantage of proteins such as myoglobin to cope with hypoxic conditions and to control the metabolism of reactive oxygen and nitrogen species. We therefore sought to establish whether myoglobin might be expressed and functionally regulated in epithelial tumors that are known to face hypoxia and oxidative stress during disease progression. We analyzed the expression of myoglobin in human epithelial cancers at both transcriptional and protein levels; moreover, we investigated the expression levels of myoglobin in cancer cell lines subjected to different conditions, including hypoxia, oxidative stress, and mitogenic stimuli. We provide evidence that human epithelial tumors, including breast, lung, ovary, and colon carcinomas, express high levels of myoglobin from the earliest stages of disease development. In human cancer cells, myoglobin is induced by a variety of signals associated with tumor progression, including mitogenic stimuli, oxidative stress, and hypoxia. This study provides evidence that myoglobin, previously thought to be restricted to myocytes, is expressed at high levels by human carcinoma cells. We suggest that myoglobin expression is part of a cellular program aimed at coping with changed metabolic and environmental conditions associated with neoplastic growth.

Iron is essential for oxygen transport because it is incorporated in the heme of the oxygen-binding proteins hemoglobin and myoglobin. An interaction between iron homeostasis and oxygen regulation is further suggested during hypoxia, in which hemoglobin and myoglobin syntheses have been reported to increase. This study gives new insights into the changes in iron content and iron-oxygen interactions during enhanced erythropoiesis by simultaneously analyzing blood and muscle samples in humans exposed to 7 to 9 days of high altitude hypoxia (HA). HA up-regulates iron acquisition by erythroid cells, mobilizes body iron, and increases hemoglobin concentration. However, contrary to our hypothesis that muscle iron proteins and myoglobin would also be up-regulated during HA, this study shows that HA lowers myoglobin expression by 35% and down-regulates iron-related proteins in skeletal muscle, as evidenced by decreases in L-ferritin (43%), transferrin receptor (TfR; 50%), and total iron content (37%). This parallel decrease in L-ferritin and TfR in HA occurs independently of increased hypoxia-inducible factor 1 (HIF-1) mRNA levels and unchanged binding activity of iron regulatory proteins, but concurrently with increased ferroportin mRNA levels, suggesting enhanced iron export. Thus, in HA, the elevated iron requirement associated with enhanced erythropoiesis presumably elicits iron mobilization and myoglobin down-modulation, suggesting an altered muscle oxygen homeostasis.

Hydrogen peroxide (H2O2) is implicated in cardiac myocyte (CM) damage during myocardial ischemia-reperfusion (IR) injury. Myoglobin (Mb) is present in CM at significant concentrations and reacts with H2O2 to yield one- and two-electron oxidants that may promote myocardial injury. Paradoxically, hearts from mice lacking Mb are more susceptible to H2O2-induced dysfunction than the corresponding controls [U. Flogel, A. Godecke, L.O. Klotz, J. Schrader, Role of myoglobin in the anti-oxidant defense of the heart, FASEB J. 18 (2004) 1156-1158]. We have overexpressed wild-type or Y103F variant of human Mb in cultured CMs to test whether Mb protects against H2O2 insult. Contrary to expectation, cells expressing WT or the Y103F Mb show increased mitochondrial dysfunction and apoptosis, and decreased ATP in response to H2O2 that follows the order native < Y103F Mb < WT human Mb consistent with the increasing pro-oxidant activity for these proteins. These data indicate that (i) Mb promotes oxidative damage to cultured CM and (ii) Mb may be a useful target for the design of inhibitors of myocardial IR injury.

We have studied the effects of different doses of thiopentone on the increase in serum myoglobin after administration of suxamethonium during inhalation induction of anaesthesia in children. Forty-three children were anaesthetized with halothane and nitrous oxide in oxygen and allocated to four groups: group S received suxamethonium 1 mg kg-1 to facilitate intubation; group ST2 received thiopentone 2 mg kg-1 and group ST4 received thiopentone 4 mg kg-1, before administration of suxamethonium 1 mg kg-1; group N did not receive thiopentone or suxamethonium. Serum myoglobin and creatine kinase (CK) concentrations were measured until 60 min after the injection of suxamethonium. Both myoglobin and CK concentrations increased in the three groups receiving suxamethonium. There were no significant differences between groups S and ST2, but the myoglobin concentration was less in group ST4 than in groups S and ST2. A significant difference in CK concentration was found only between groups ST2 and ST4 at 60 min. In group N, both values remained reasonably constant. Thiopentone 4 mg kg-1, but not 2 mg kg-1, attenuated the increase. The results indicate that to prevent a marked elevation in serum myoglobin after administration of suxamethonium, thiopentone 4 mg kg-1 should be administered.