Search

Acinetobacter baumannii is a catalase-positive Gram-negative bacterial pathogen that causes severe infections among compromised patients. Among its noteworthy regulatory mechanisms, this microorganism regulates its lifestyle through the blue light using flavin (BLUF) protein BlsA. This protein regulates a diverse set of cellular processes that include, but are not limited to, motility, biofilm formation, phenylacetic acid metabolism, iron uptake, and catalase activity. We set out to determine how A. baumannii regulates catalase activity and other related oxidative stress phenotypes in response to light. Notably, because A. baumannii ATCC 17978 encodes four catalase homologs – which we refer to as KatA, KatE, KatE2, and KatG – we also aimed to show which of these enzymes exhibit light- and BlsA-dependent activity. Our work not only provides insight into the general function of all four catalase homologs and the impact of light on these functions, but also directly identifies KatE as a BlsA-regulated enzyme. We further demonstrate that the regulation of KatE by BlsA is dependent on a lysine residue that we previously demonstrated to be necessary for the regulation of surface motility. Furthermore, we show that BlsA's five most-C-terminal residues – previously considered dispensable for BlsA's overall function – are necessary for the light-independent and light-dependent regulation of catalase and superoxide dismutase activities, respectively. We hypothesize that these identified critical residues are necessary for BlsA's interaction with protein partners including the transcriptional regulators Fur and BfmR. Together these data expand the understanding regarding how A. baumannii uses light as a signal to control oxidative stress resistance mechanisms that are critical for its pathophysiology. [ABSTRACT FROM AUTHOR]

Chronic inflammation and long-standing oxidative stress are potential predisposing factors for developing malignancies, including ovarian cancer (OVCA). Information on the association of ovarian chronic abnormal conditions, including polycystic ovarian syndrome (PCOS), with the development of OVCA is unknown. The goal of this study was to examine if polycystic ovarian conditions are associated with OVCA development. In the exploratory study, 3-4-year-old laying hens were randomly selected and examined for the presence of polycystic ovaries with cancer (PCOC). In the prospective study, hens were monitored by ultrasound scanning to detect the incidence of a polycystic ovaries and subsequent development of OVCA. Tissues from normal ovaries and PCOC were examined for macrophage infiltration, expression of interleukin-16, and superoxide dismutase 2. The exploratory study detected spontaneous PCOC at early and late stages in hens. PCOC in hens were accompanied with influx of macrophages (17.33 ± 2.26 in PCOC at the early stage and 24.24 ± 2.5 in PCOC at the late stage in 20 mm2 areas of tissue as compared with 6.77 ± 1.58 in normal hens). Expression of interleukin-16 was more than 2.5-fold higher and superoxide dismutase 2 was approximately 3-fold higher in PCOC hens than normal hens. The prospective study showed the development of OVCA in some hens with polycystic ovarian condition (PCO). PCOC development in hens was associated with chronic inflammation in the ovary. Laying hens may represent a potential model for the study of spontaneous PCOS and its long-term risk of PCOC development. [ABSTRACT FROM AUTHOR]

Free radical-induced lipid oxidation under oxidative stress has been implicated in a number of human diseases. Isoprostanes (IsoPs), isomers of prostaglandins, are one of the major classes of oxidation products derived from this oxidation process. Measurement of the levels of IsoPs by Mass Spectrometry-based methods has become the "gold standard" biomarker of oxidative stress in vivo. Significant advances have been made in understanding this important pathway of lipid peroxidation since the discovery of IsoP formation in vivo 18 years ago. Studies from our laboratory and others are discussed that have provided insights into the mechanism of formation. Furthermore, new independent studies have demonstrated that IsoPs are the most reliable available marker of lipid peroxidation in vivo, and recent work examining IsoP formation has provided valuable information about the pathogenesis of numerous human diseases. Thus, the complexity of the IsoP pathway has expanded, providing novel insights into mechanisms of lipid peroxidation in vivo and allowing investigators to explore the role of oxidative stress in human disease. [ABSTRACT FROM AUTHOR]

Alzheimer's disease (AD) is a growing public health problem worldwide. Clinically, AD is a progressive neurodegenerative disorder characterized by a global cognitive decline. Accumulating evidence indicates that reactive oxygen species-mediated reactions, particularly of neuronal lipids, are extensive in those AD brain areas directly involved in the disease processes. Traditional views claim that oxidative-mediated tissue injury in the AD brain is the result of neurodegeneration. In recent years, numerous investigations have pointed to the functional importance of oxidative imbalance as a crucial event in mediating AD pathogenesis. The availability of specific and sensitive markers to monitor in vivo oxidative stress, in combination with studies performed in living patients with clinical diagnosis of AD are helping us to elucidate these issues. The evidence we have accumulated so far clearly indicates that oxidative imbalance and subsequent oxidative stress are early events during the evolution of the disease, and secondary to specific mechanism(s) present in AD but not in other neurodegenerative diseases. These new concepts implicate that this phenomenon may play a more important role in AD pathogenesis than previously anticipated, and that any therapeutic intervention targeting oxidative stress should be initiated at the earliest possible stage of the disease. [ABSTRACT FROM AUTHOR]