Melatonin is a molecule present in a multitude of taxa and may be ubiquitous in organisms. It has been found in bacteria, unicellular eukaryotes, macroalgae, fungi, plants and animals. A primary ...biological function of melatonin in primitive unicellular organisms is in antioxidant defence to protect against toxic free radical damage. During evolution, melatonin has been adopted by multicellular organisms to perform many other biological functions. These functions likely include the chemical expression of darkness in vertebrates, environmental tolerance in fungi and plants, sexual signaling in birds and fish, seasonal reproductive regulation in photoperiodic mammals, and immunomodulation and anti‐inflammatory activity in all vertebrates tested. Moreover, its waning production during aging may indicate senescence in terms of a bio‐clock in many organisms. Conversely, high melatonin levels can serve as a signal of vitality and health. The multiple biological functions of melatonin can partially be attributed to its unconventional metabolism which is comprised of multi‐enzymatic, pseudo‐enzymatic and non‐enzymatic pathways. As a result, several bioactive metabolites of melatonin are formed during its metabolism and some of the presumed biological functions of melatonin reported to date may, in fact, be mediated by these metabolites. The changing biological roles of melatonin seem to have evolved from its primary function as an antioxidant.
: Alzheimer’s disease (AD) is a highly complex neurodegenerative disorder of the aged that has multiple factors which contribute to its etiology in terms of initiation and progression. This review ...summarizes these diverse aspects of this form of dementia. Several hypotheses, often with overlapping features, have been formulated to explain this debilitating condition. Perhaps the best‐known hypothesis to explain AD is that which involves the role of the accumulation of amyloid‐β peptide in the brain. Other theories that have been invoked to explain AD and summarized in this review include the cholinergic hypothesis, the role of neuroinflammation, the calcium hypothesis, the insulin resistance hypothesis, and the association of AD with peroxidation of brain lipids. In addition to summarizing each of the theories that have been used to explain the structural neural changes and the pathophysiology of AD, the potential role of melatonin in influencing each of the theoretical processes involved is discussed. Melatonin is an endogenously produced and multifunctioning molecule that could theoretically intervene at any of a number of sites to abate the changes associated with the development of AD. Production of this indoleamine diminishes with increasing age, coincident with the onset of AD. In addition to its potent antioxidant and anti‐inflammatory activities, melatonin has a multitude of other functions that could assist in explaining each of the hypotheses summarized above. The intent of this review is to stimulate interest in melatonin as a potentially useful agent in attenuating and/or delaying AD.
This review summarizes the advances that have been made in terms of the identified functions of melatonin in plants. Melatonin is an endogenously-produced molecule in all plant species that have been ...investigated. Its concentration in plant organs varies in different tissues, e.g., roots versus leaves, and with their developmental stage. As in animals, the pathway of melatonin synthesis in plants utilizes tryptophan as an essential precursor molecule. Melatonin synthesis is inducible in plants when they are exposed to abiotic stresses (extremes of temperature, toxins, increased soil salinity, drought, etc.) as well as to biotic stresses (fungal infection). Melatonin aids plants in terms of root growth, leaf morphology, chlorophyll preservation and fruit development. There is also evidence that exogenously-applied melatonin improves seed germination, plant growth and crop yield and its application to plant products post-harvest shows that melatonin advances fruit ripening and may improve food quality. Since melatonin was only discovered in plants two decades ago, there is still a great deal to learn about the functional significance of melatonin in plants. It is the hope of the authors that the current review will serve as a stimulus for scientists to join the endeavor of clarifying the function of this phylogenetically-ancient molecule in plants and particularly in reference to the mechanisms by which melatonin mediates its multiple actions.
This paper explores the processes of meaning‐making around femicide in Guatemala, highlighting how particular bodies and spaces are pre‐figured as “disposable” through racialised and gendered ...imaginaries. I draw upon Butlerian epistemologies of violence and indigenous and feminist scholarship from Guatemala and the Americas to analyse why femicides are scripted differently for victims who emerge in “public” spatial formations. Grounded in analysis of the main national newspaper’s reporting and the state’s regulatory framework around violence, and supplemented with interviews and ethnographic observations that emerged in the context of a high‐profile “private” femicide, I argue that “public” victims are read relationally against two subjects who—through reactivated historical scripts of violence—help communicate public victims’ disposability. This paper contributes a rich account of the socio‐spatial logics informing how bodies matter in Guatemala; more broadly, it emphasises the productive work of states and powerful institutions like media in reinforcing hierarchies between victims of femicide.
Resumen
Este artículo explora los procesos mediante los cuales se interpreta el femicidio en Guatemala, enfatizando los imaginarios racistas y sexistas que prefiguran ciertos cuerpos y espacios como “desechables”. Mi trabajo se basa en epistemologías Butlerianas de la violencia y las obras de mujeres indígenas y feministas de Guatemala y las Américas, con el fin de analizar la manera particular en que se presentan los casos de víctimas de femicidio que emergen de formaciones espaciales “públicas”. Basándome en un análisis de reportajes del periódico de mayor circulación en el país y las políticas estatales alrededor de la violencia, suplementado con entrevistas y observaciones etnográficas que emergieron en el contexto de un caso considerado de alto impacto, sostengo que las víctimas “públicas” se presentan en relación a dos sujetos quienes – a través de discursos históricos reactivados – comunican la desechabilidad de las víctimas “públicas”. Este artículo brinda un recuento de las lógicas socioespaciales que informan el significado de los cuerpos en Guatemala; en términos más generales, enfatiza el trabajo productivo de los estados y de instituciones poderosas como los medios de comunicación, para reforzar las jerarquías de las víctimas de femicidio.
► The role of melatonin in the regulation of autophagy and mitophagy. ► The molecular mechanisms by which melatonin influences apoptosis. ► The function of melatonin in reducing cellular loss in ...specific disease states.
Oxidative stress plays an essential role in triggering many cellular processes including programmed cell death. Proving a relationship between apoptosis and reactive oxygen species has been the goal of numerous studies. Accumulating data point to an essential role for oxidative stress in the activation of autophagy. The term autophagy encompasses several processes including not only survival or death mechanisms, but also pexophagy, mitophagy, ER-phagy or ribophagy, depending of which organelles are targeted for specific autophagic degradation. However, whether the outcome of autophagy is survival or death and whether the initiating conditions are starvation, pathogens or death receptors, reactive oxygen species are invariably involved. The role of antioxidants in the regulation of these processes, however, has been sparingly investigated. Among the known antioxidants, melatonin has high efficacy and, in both experimental and clinical situations, its protective actions against oxidative stress are well documented. Beneficial effects against mitochondrial dysfunction have also been described for melatonin; thus, this indoleamine seems to be linked to mitophagy. The present review focuses on data and the most recent advances related to the role of melatonin in health and disease, on autophagy activation in general, and on mitophagy in particular.
The importance of pigeons as reservoirs and carriers of Cryptococcus neoformans and other species of this genus is well-known; however, less is known about their role as reservoirs and carriers of ...other yeasts that impact public health.
The present study was performed on Gran Canaria Island to define yeasts other than Cryptococcus spp. that have been reported to impact public health and which could be carried by pigeons.
Samples were obtained from 83 pigeon lofts (Columba livia); moreover, 331 crop samples, 331 cloacal samples and 174 dropping samples were collected. In addition, 17 dropping samples were taken from a total of 17 public squares. Samples were inoculated on Sabouraud dextrose agar with chloramphenicol.
Different yeast species, i.e. Candida guilliermondii (24.36%), Candida kefyr (1.21%), Saccharomyces cerevisiae (2.43%), and Trichosporon asahii (1.21%) were isolated for the first time from the cloaca. The most frequently isolated yeast from the crop, cloaca and dropping samples from lofts was C. guilliermondii (30.46%, 24.36% and 49.37%, respectively). In addition, for the first time, C. kefyr (3.65%), Candida pelliculosa (2.43%), Candida rugosa (1.21%), T. asahii (3.65%), Trichosporon mucoides (3.65%) and Prototheca wickerhamii (1.21%) were obtained from crop samples; Candida pelliculosa (1.20%), T. asahii (9.63%) and T. mucoides (7.22%) were isolated from dropping samples in the lofts. Candida albicans was the most frequently isolated yeast in dropping samples collected in public squares.
It can be assumed that pigeons and their droppings act as carriers and reservoirs of Candida spp. and other zoonotic yeasts.
The experimental data obtained from both human and rodent studies suggest that melatonin may have utility in the treatment of several cardiovascular conditions. In particular, melatonin's use in ...reducing the severity of essential hypertension should be more widely considered. In rodent studies melatonin has been shown to be highly effective in limiting abnormal cardiac physiology and the loss of critical heart tissue resulting from ischemia/reperfusion injury. Melatonin may also be useful in reducing cardiac hypertrophy in some situations and thereby limiting the frequency of heart failure. Finally, some conventional drugs currently in use have cardiotoxicity as a side-effect. Based on studies in rodents, melatonin, due to its multiple anti-oxidative actions, is highly effective in abrogating drug-mediated damage to the heart. Taken together, the findings from human and animal studies support the consideration of melatonin as a cardioprotective agent.
Abstract
Within the last decade, the synthesis of melatonin in and its functions at the level of the peripheral reproductive organs has come into better focus. Melatonin is produced at several ...reproductive organ sites, e.g., the oocyte, ovarian follicular cells and the placental cytotrophoblasts. Moreover, these cells also contain membrane receptors for this indoleamine. In addition, via the free radical scavenging activity of melatonin and its metabolites, oxidative stress is reduced in all reproductive organ cells ensuring their optimal function. Enhancement of oocyte maturation and preservation of oocyte quality may be major functions of melatonin. Oocyte damage reduces successful fertilization and the development of a healthy fetus. The findings that melatonin protects the oocyte from toxic oxygen species have implications for improving the outcome of in vitro fertilization-embryo transfer procedures, as already shown in two published reports. Some actions of melatonin in the placenta may be context specific. Thus, melatonin is believed to function in the maintenance of optimal placental homeostasis by deferring apoptosis of villous cytotrophoblasts, while protecting syncytiotrophoblasts from oxidative damage. Melatonin reduces oxidative damage in the placenta and may improve hemodynamics and nutrient transfer at the placental-uterine interface. The use of melatonin to treat preeclampsia should also be considered.
Powerful international development institutions have called for a 'gender data revolution.' They posit that progress on gender equality depends upon our collective ability to close 'the gender data ...gap,' by which they mean that we know less about women's lives than men's in statistical terms. Some feminists within and outside the academy treat the gender data revolution with suspicion, likening it to a 'measurement obsession' (Liebowitz and Zwingel
2014
) that is overly quantitative (Buss
2015
) and ill-fit to capture the complexities of gender subordination. In this paper, we suggest that feminist geographers as academics and scholar-activists have a unique and important contribution to make to the gender data debate, which at present is largely aspatial. Drawing on empirical examples we first illustrate how feminist geography's conceptual and methodological contributions enrich the gender data debate; second, we reflect on the possibilities and limitations of a practical intervention that we are currently staging as co-founders of a feminist research venture that seeks to shape policymaking, critically considering the possibilities and limitations of such an endeavour.
Non-typeable Haemophilus influenzae (NTHi) is a common opportunistic bacterial pathogen that primarily infects the respiratory mucosa. This study was conducted to assess clinical and microbiological ...data related to disease severity in patients with lower respiratory tract infections caused by NTHi in a tertiary care hospital in Mexico. NTHi isolates were subjected to serotyping, antimicrobial susceptibility evaluationand analyses of β-lactamase production, genetic relatednessand biofilm formation. Clinical and demographic data were retrieved from patients' records. The mean age of the patients was 40.3 years; the majority (n=44, 72.1 %) were male. The main comorbidities were arterial hypertension (n=22, 36.1 %) and diabetes mellitus (n=17, 27.9 %). NTHi isolates (n=98) were recovered from tracheal aspirate (n=57, 58.2 %), sputum (n=26, 26.5 %)and bronchial aspirate (n=15, 15.3 %) specimens. Low resistance to cefotaxime (n=0, 0.0 %), rifampin (n=1, 1.1 %) and chloramphenicol (n=3, 3.2 %) and greater resistance to ampicillin (n=30, 32.3 %) and trimethoprim-sulfamethoxazole (n=49, 52.7 %) were detected. β-Lactamase production was found in 17 (17.3 %) isolates. Isolates displayed high genetic diversity, and only 10 (10.2 %) were found to be biofilm producers. The antimicrobial susceptibility patterns of biofilm-producing and non-producing isolates did not differ. Biofilm production was associated with prolonged hospital stay (P=0.05). Lower respiratory NTHi isolates from Mexico showed low antimicrobial resistance and weak biofilm production. Younger age was correlated with lower Acute Physiology and Chronic Health Evaluation II score (moderate, P=0.07; severe, P=0.03).
PDF
