Metabolic pathways in immune senescence and inflammaging: Novel therapeutic strategy for chronic inflammatory lung diseases. An EAACI position paper from the Task Force for Immunopharmacology.

The accumulation of senescent cells drives inflammaging and increases morbidity of chronic inflammatory lung diseases. Immune responses are built upon dynamic changes in cell metabolism that supply energy and substrates for cell proliferation, differentiation, and activation. Metabolic changes imposed by environmental stress and inflammation on immune cells and tissue microenvironment are thus chiefly involved in the pathophysiology of allergic and other immune-driven diseases. Altered cell metabolism is also a hallmark of cell senescence, a condition characterized by loss of proliferative activity in cells that remain metabolically active. Accelerated senescence can be triggered by acute or chronic stress and inflammatory responses. In contrast, replicative senescence occurs as part of the physiological aging process and has protective roles in cancer surveillance and wound healing. Importantly, cell senescence can also change or hamper response to diverse therapeutic treatments. Understanding the metabolic pathways of senescence in immune and structural cells is therefore critical to detect, prevent, or revert detrimental aspects of senescence-related immunopathology, by developing specific diagnostics and targeted therapies. In this paper, we review the main changes and metabolic alterations occurring in senescent immune cells (macrophages, B cells, T cells). Subsequently, we present the metabolic footprints described in translational studies in patients with chronic asthma and chronic obstructive pulmonary disease (COPD), and review the ongoing preclinical studies and clinical trials of therapeutic approaches aiming at targeting metabolic pathways to antagonize pathological senescence. Because this is a recently emerging field in allergy and clinical immunology, a better understanding of the metabolic profile of the complex landscape of cell senescence is needed. The progress achieved so far is already providing opportunities for new therapies, as well as for strategies aimed at disease prevention and supporting healthy aging.

AllergoOncology: Opposite outcomes of immune tolerance in allergy and cancer.

While desired for the cure of allergy, regulatory immune cell subsets and nonclassical Th2-biased inflammatory mediators in the tumour microenvironment can contribute to immune suppression and escape of tumours from immunological detection and clearance. A key aim in the cancer field is therefore to design interventions that can break immunological tolerance and halt cancer progression, whereas on the contrary allergen immunotherapy exactly aims to induce tolerance. In this position paper, we review insights on immune tolerance derived from allergy and from cancer inflammation, focusing on what is known about the roles of key immune cells and mediators. We propose that research in the field of AllergoOncology that aims to delineate these immunological mechanisms with juxtaposed clinical consequences in allergy and cancer may point to novel avenues for therapeutic interventions that stand to benefit both disciplines.

AllergoOncology - the impact of allergy in oncology: EAACI position paper.

Th2 immunity and allergic immune surveillance play critical roles in host responses to pathogens, parasites and allergens. Numerous studies have reported significant links between Th2 responses and cancer, including insights into the functions of IgE antibodies and associated effector cells in both antitumour immune surveillance and therapy. The interdisciplinary field of AllergoOncology was given Task Force status by the European Academy of Allergy and Clinical Immunology in 2014. Affiliated expert groups focus on the interface between allergic responses and cancer, applied to immune surveillance, immunomodulation and the functions of IgE-mediated immune responses against cancer, to derive novel insights into more effective treatments. Coincident with rapid expansion in clinical application of cancer immunotherapies, here we review the current state-of-the-art and future translational opportunities, as well as challenges in this relatively new field. Recent developments include improved understanding of Th2 antibodies, intratumoral innate allergy effector cells and mediators, IgE-mediated tumour antigen cross-presentation by dendritic cells, as well as immunotherapeutic strategies such as vaccines and recombinant antibodies, and finally, the management of allergy in daily clinical oncology. Shedding light on the crosstalk between allergic response and cancer is paving the way for new avenues of treatment.

Hormesis, cellular stress response, and redox homeostasis in autism spectrum disorders.

In the United States, 1.1-1.5% of children have been diagnosed with autism spectrum disorders (ASD), corresponding to a 30% increase in incidence and prevalence. Social and communication impairments are the main signs and symptoms of ASD, and currently available medications have been ineffective in reducing these core deficits. Observational studies have indicated that children with ASD tend to show improved cognition and behavior after febrile illness, which is associated with alteration of metabolic pathways, leading to cellular stress responses and increased expression of heat shock proteins (Hsps). Sulforaphane and hydroxytyrosol, phytochemicals derived from cruciferous vegetables and extra virgin olive oil, respectively, can induce metabolic effects in cellular stress responses that are similar to those produced by fever. Thus, modulation of endogenous cellular defense mechanisms may be an innovative approach for therapeutic intervention in ASD and other disorders associated with neuroinflammation and neurodegeneration. This Review introduces the hormetic dose-response concept and presents possible mechanisms and applications for neuroprotection. We address the emerging role of Hsps in the neuroprotective network of redox stress-responsive mechanisms and propose the potential therapeutic utility of the nutritional antioxidants sulforaphane and hydroxytyrosol against particular signs and symptoms of ASD. We argue that such research findings must be approached with pragmatism and prudence. It is vital to capitalize on recent and ongoing investments in brain science research and to refine neuroscientific knowledge and capability for more accurate diagnosis and safe, effective, and ethically sound treatment of ASD and other neuropsychiatric spectrum disorders. © 2016 Wiley Periodicals, Inc.

Structural similarities of human and mammalian lipocalins, and their function in innate immunity and allergy.

Owners and their domestic animals via skin shedding and secretions, mutually exchange microbiomes, potential pathogens and innate immune molecules. Among the latter especially lipocalins are multifaceted: they may have an immunomodulatory function and, furthermore, they represent one of the most important animal allergen families. The amino acid identities, as well as their structures by superposition modeling were compared among human lipocalins, hLCN1 and hLCN2, and most important animal lipocalin allergens, such as Can f 1, Can f 2 and Can f 4 from dog, Fel d 4 from cats, Bos d 5 from cow's milk, Equ c 1 from horses, and Mus m 1 from mice, all of them representing major allergens. The ß-barrel fold with a central molecular pocket is similar among human and animal lipocalins. Thereby, lipocalins are able to transport a variety of biological ligands in their highly conserved calyx-like cavity, among them siderophores with the strongest known capability to complex iron (Fe(3+) ). Levels of human lipocalins are elevated in nonallergic inflammation and cancer, associated with innate immunoregulatory functions that critically depend on ligand load. Accordingly, deficient loading of lipocalin allergens establishes their capacity to induce Th2 hypersensitivity. Our similarity analysis of human and mammalian lipocalins highlights their function in innate immunity and allergy.

Galanin modulates human and murine neutrophil activation in vitro.

AIMS: Polymorphonuclear neutrophils are key players in innate immunity. The innate immune system needs to be tightly controlled to ensure proper activation but also no overactivation. Galanin has been shown to regulate inflammatory reactions, and therefore, we aimed to elucidate the expression of galanin and its three receptors (GAL1 -GAL3 ) in polymorphonuclear neutrophils and to evaluate whether galanin exerts direct or indirect effects on human and murine polymorphonuclear neutrophils. METHODS: Human peripheral polymorphonuclear neutrophils were isolated from fresh blood of healthy donors, and murine polymorphonuclear neutrophils were isolated from bone marrow of C57BL/6N mice. Gene expression was evaluated by qRT-PCR. As a marker for polymorphonuclear neutrophil activation, CD11b integrin surface expression was measured by FACS analysis. Furthermore, a label-free technology measuring ligand-induced dynamic mass redistribution was used to evaluate the response of polymorphonuclear neutrophils to galanin. RESULTS: GAL2 receptor expression was found in both human and murine polymorphonuclear neutrophils, galanin and GAL3 receptor were exclusively expressed in murine bone marrow polymorphonuclear neutrophils, and GAL1 receptor was not detectable in polymorphonuclear neutrophils of either species. Galanin treatment was not able to induce CD11b integrin surface expression or dynamic mass redistribution in human polymorphonuclear neutrophils and murine bone marrow polymorphonuclear neutrophils. However, galanin treatment significantly enhanced the response of polymorphonuclear neutrophils of both species to interleukin-8. CONCLUSION: Galanin can be regarded as an immunomodulatory peptide as it can sensitize polymorphonuclear neutrophils towards pro-inflammatory cytokines in humans and mice.

Texture analysis of cosmetic/pharmaceutical raw materials and formulations.

OBJECTIVES: The purpose of this work was to quantify textural properties of cosmetic and pharmaceutical raw materials. METHODS: Textural parameters such as hardness, consistency, cohesiveness, index of viscosity, stickiness and resilience were evaluated. The measurements were performed using texture analyser - a tensile metre equipped with special probes (in the form of acrylic cylinder and stainless steel sphere), which can penetrate the measured sample of a product recording the force, distance and time. The instrument simulates the action of a human finger touching the surface and probing the properties of an object. The set-up has been previously shown to quantify the rheological/textural properties of cosmetic and pharmaceutical products such as creams, lotion and gels as well as rheological behaviour of human skin. RESULTS AND CONCLUSIONS: The results include the analysis of water, glycerine and mineral oil as well as aqueous solutions of thickeners such as Acrylates/C10-30 Alkyl Acrylate Crosspolymer (Ultrez-20 obtained from Noveon) and carbomer. Solutions of common surfactants and complex surfactant formulations such as shampoos have also been investigated. The results, in the form plots of force as a function of time or distance, resulting from slow bidirectional probe movement (submergence and desubmergence) in the analysed fluid, were interpreted by considering buoyancy, drag and viscous drag force given by Stokes equation. The data can be used to correlate with tactile evaluations of products by trained panel evaluations.

Interaction of mineral salts with the skin: a literature survey.

There is growing scientific evidence that the health, well-being and the attractiveness of the skin are strongly influenced by nutrition. Consumers recognize this and have supported the creation of a global cosmeceuticals market estimated in 2010 at $27.2 billion. Early in 2011, the US Department of Health and Human Services and Department of Agriculture issued the Dietary Guidelines for Americans, 2010. Twelve vitamins and nine minerals were recognized as essential. The minerals include calcium, copper, iron, magnesium, phosphorus, selenium, zinc, potassium and sodium. Although the topical benefits of several minerals such as zinc, magnesium and iron are recognized and, in some cases, approved by the FDA, the topical benefits of the others to the skin are largely unexplored and unexploited. This review attempts to summarize what has been published in the literature on the interactions of the eight of the nine essential elements with the skin.

Grey hair: clinical investigation into changes in hair fibres with loss of pigmentation in a photoprotected population.

Loss of pigmentation in hair fibres is one of the most obvious phenotypic changes with ageing and has been a topic of increasing interest in the study of follicle biology. The onset of greying brings cosmetic complaints that grey fibres are wild or difficult to manage. Of course, these perceptions may be the consequence of visual obviousness rather than underlying physical or chemical differences. Although several studies have compared pigmented and unpigmented fibres, few have tried to control genetic and ethnic difference as well as extrinsic factors such as photoexposure and chemical treatment. We have recruited subjects with salt-and-pepper hair from a population of Old Order Mennonites who, for cultural reasons, are not only prohibited from chemically treating their hair but also limit their exposure to sunlight. Hair samples were examined for elemental composition, surface energy, Young's modulus, break stress, bending modulus, shear modulus and water sorption/desorption isotherm. The parameters were evaluated statistically for global differences, individual differences and typical individual differences. Consistent with previous published literature, few global differences were found between pigmented and unpigmented hair across the population. We do find that many individual subjects had differences between pigmented and unpigmented fibres. These differences tend to be more pronounced in bulk than in surface properties. The small differences in mechanical properties and moisture uptake and loss lend support to the perception by consumers that grey hair is wilder, drier and less manageable.

[Glucocorticoid induced TNFR-related protein (GITR) as marker of human regulatory T cells: expansion of the GITR(+)CD25⁻ cell subset in patients with systemic lupus erythematosus]. / Glucocorticoid-induced TNFR-related protein (GITR) come marker di cellule T regolatorie umane: espansione della sottopopolazione cellulare GITR(+)CD25⁻ in pazienti affetti da lupus eritematoso sistemico.

OBJECTIVES: Regulatory T cells (T(REG)) represent a T cell subset able to modulate immune response by suppressing autoreactive T-lymphocytes. The evidence of a reduced number and an impaired function of this cell population in autoimmune/inflammatory chronic diseases led to the hypothesis of its involvement in the pathogenesis of these disorders. Glucocorticoid-induced TNFR-related protein (GITR) is a well known marker of murine T(REG) cells, but little is known in humans. The aim of this study was to investigate the characteristics of T(REG) cells in systemic lupus erythematosus (SLE) and the potential role of GITR as marker of human T(REG). METHODS: Nineteen SLE patients and 15 sex- and age-matched normal controls (NC) were enrolled. CD4(+) T cells were magnetic sorted from peripheral blood by negative selection. Cell phenotype was analyzed through flow-cytometry using primary and secondary antibodies and real time polymerase-chain reaction (PCR) using TaqMan probes. RESULTS: The CD25(high)GITR(high) subset was significantly decreased in SLE patients with respect to NC (0.37±0.21% vs 0.72±0.19%; p<0.05). On the opposite, the CD25⁻GITR(high) cell population was expanded in the peripheral blood of SLE patients (3.5±2.25 vs 0.70±0.32%, p<0.01). Interestingly, FoxP3 at mRNA level was expressed in both CD25⁻GITR(high) and CD25(high)GITR(high) cells, suggesting that both cell subsets have regulatory activity. CONCLUSIONS: CD4(+)CD25⁻GITR(high) cells are increased in SLE as compared to NC. The expression of high level of GITR, but not CD25, on FoxP3+ cells appears to point to a regulatory phenotype of this peculiar T cell subset.

Fluorescence and coloration of grey hair.

Grey hair samples were collected from 11 individuals and separated into un-pigmented and pigmented fibres (International Hair Importers). Fluorescence measurements were obtained by using a double-grating fluorescence spectrophotometer and a bifurcated fibre optics accessory to measure the spectra directly from the surface of hair at various distances from the fibre root. Colour measurements were carried out by using a Hunter colorimeter. The fluorescence spectra of un-pigmented hair obtained by the excitation at 290 nm show a peak at 356 nm [tryptophan (Trp)], and multi-peak emissions in the range from 395 to 500 nm. A significant variation in the Trp emission intensity at 356 nm vs. the intensity of emission in the 395-500 nm range was observed for hair collected from various individuals with yellow coloured hair producing stronger relative emission in 395-500 nm range. Quantitative measurements of coloration and the calculation of the Yellowness Index (YI) showed linear correlation between YI and the ratio of fluorescence intensities I(440)/I(356) The spectra obtained by excitation at 320 nm showed the emission peaks at 395 nm (unidentified), 420 nm (N-formylkynurenine), 460 nm (kynurenine), and 495 nm (3-hydroxykynurenine), which are the products of oxidative or metabolic conversion of tryptophan. Un-pigmented, yellow hair showed a build-up of the fluorescence band corresponding to 3-hydroxykynurenine at 495 nm. The data also showed the fluorescence quenching effect of melanin resulting in the lowering of the fluorescence intensity of pigmented hair. The spectra obtained at various positions along the fibres demonstrated gradual photo-decomposition of hair chromophores during their lifetimes. This was indicated by a decrease of Trp fluorescence intensity, which was relatively fast (8.10(-4)-1.5.10(-3) [day(-1)] as calculated for hair obtained from various individuals) for un-pigmented hair and slower for pigmented hair. A decrease in Trp emission was accompanied by an increase in the yellow coloration toward the ends of un-pigmented fibres.

Activation of the alternative complement pathway in canine normal serum by Paracoccidioides brasiliensis / Ativação da via alternativa do complemento em soro de cão normal por Paracoccidioides brasiliensis

The dimorphic fungus Paracoccidioides brasiliensis is the etiological agent of paracoccidioidomycosis, a human granulomatous disease. Recently the first case of natural disease in dogs was reported. The complement system is an important effector component of humoral immunity against infectious agents. Therefore, the aim of this study was to evaluate the activation of the dog alternative complement pathway by P. brasiliensis. Initially, the ability of erythrocytes of guinea pig, rabbit, sheep, chicken and swine to activate the dog alternative pathway was evaluated. The guinea pig erythrocytes showed the greatest capacity to activate dog alternative pathway. The alternative (AH50) hemolytic activity was evaluated in 27 serum samples from healthy dogs and the mean values were 87.2 AH50/ml. No significant differences were observed in relation to sex and age. The alternative pathway activation by P. brasiliensis was higher in serum samples from adult dogs when compared to puppies and aged dogs (p < 0.05). This is the first report of dog alternative complement pathway activation by P. brasiliensis and suggests that it may play a protective role in canine paracoccidioidomycosis.

O fungo dimórfico Paracoccidioides brasiliensis é o agente etiológico da paracoccidioidomicose, uma doença granulomatosa humana. Recentemente, foi relatado o primeiro caso da doença natural em cães. O sistema complemento é um importante componente efetor da imunidade humoral contra agentes infecciosos. Portanto, o objetivo deste trabalho foi avaliar a ativação da via alternativa do complemento canina pelo P. brasiliensis. Inicialmente, foi avaliada a capacidade de eritrócitos de cobaia, coelho, carneiro, galinha e suíno ativarem a via alternativa do complemento canino. Os eritrócitos de cobaia apresentaram maior capacidade de ativar a via alternative do complemento canino. A atividade hemolítica da via alternativa (AH50) foi avaliada em 27 amostras de soro de cães saldáveis e os valores médios observados foram de 87,2 AH50/ml. Não foi observada diferença significativa ao sexo e idade. A ativação da via alternativa pelo P. brasiliensis foi maior nas amostras de soro de cães adultos quando comparada aos cães filhotes e idosos (p < 0.05). Este é o primeiro relato da ativação da via alternative do complemento canino pelo fungo P. brasiliensis e sugere que pode ter um papel protetor na paracoccidioidomicose canina.

Activation of the alternative complement pathway in canine normal serum by Paracoccidioides brasiliensis.

The dimorphic fungus Paracoccidioides brasiliensis is the etiological agent of paracoccidioidomycosis, a human granulomatous disease. Recently the first case of natural disease in dogs was reported. The complement system is an important effector component of humoral immunity against infectious agents. Therefore, the aim of this study was to evaluate the activation of the dog alternative complement pathway by P. brasiliensis. Initially, the ability of erythrocytes of guinea pig, rabbit, sheep, chicken and swine to activate the dog alternative pathway was evaluated. The guinea pig erythrocytes showed the greatest capacity to activate dog alternative pathway. The alternative (AH50) hemolytic activity was evaluated in 27 serum samples from healthy dogs and the mean values were 87.2 AH50/ml. No significant differences were observed in relation to sex and age. The alternative pathway activation by P. brasiliensis was higher in serum samples from adult dogs when compared to puppies and aged dogs (p ≤ 0.05). This is the first report of dog alternative complement pathway activation by P. brasiliensis and suggests that it may play a protective role in canine paracoccidioidomycosis.

Endothelial dysfunction in vivo is related to monocyte resistin mRNA expression.

BACKGROUND: Resistin could be the linkage between the adipose tissue and the insulin resistance. In humans, the role of resistin on metabolic and vascular homeostasis is not well defined. The aim of this study was to investigate the possible association between resistin expression and insulin resistance. METHODS AND RESULTS: We evaluated the relationship between monocyte expression of mRNA and anthropometric and metabolic parameters of insulin resistance. We focused on the potential role of resistin on endothelial function. Thirty-nine patients with metabolic syndrome (MS) and clinically free from cardiovascular disease, and 15 healthy subjects were included in this study. All subjects underwent clinical examination, assessment of haematochemical parameters, bioimpedentiometry, measurement of monocyte resistin mRNA and of brachial-artery flow-mediated vasodilation (FMV). Patients with MS showed higher levels of interleukin-6 (IL; 2.1 +/- 1.2 vs. 1.2 +/- 0.9 pg/mL, P < 0.05) and reduced FMV (5.4 +/- 3.9 vs. 8.3 +/- 3.1%, P < 0.05). The subjects were divided into two groups: (i) subjects with high expression mRNA resistin levels and (ii) subjects with low or not detectable; Group 1 was younger (50 +/- 13 vs. 59 +/- 11 years, P = 0.01), showed higher IL-6 values (2.3 +/- 1.2 vs. 1.6 +/- 1.2, P = 0.03) and lower values of FMV (4.3 +/- 2.8 vs. 7.4 +/- 3.9%, P = 0.003). With univariate analysis monocyte mRNA showed a significant positive correlation with waist circumference (r = 0.27, P < 0.05) and IL-6 (r = 0.26, P < 0.05) and a negative correlation with FMV (r = -0.38, P < 0.005). With multivariate regression analysis brachial-artery diameter, low-density lipoprotein cholesterol, high-density lipoprotein cholesterol, IL-6 and RNAm resistin expression were independent predictors of reduced FMV. CONCLUSIONS: mRNA resistin negatively influences FMV, and is a possible in vivo index of endothelial dysfunction.

Accreditation experience of radioisotope metrology laboratory of Argentina.

This work presents the experience developed by the Radioisotope Metrology Laboratory (LMR), of the Argentine National Atomic Energy Commission (CNEA), as result of the accreditation process of the Quality System by ISO 17025 Standard. Considering the LMR as a calibration laboratory, services of secondary activity determinations and calibration of activimeters used in Nuclear Medicine were accredited. A peer review of the (alpha/beta)-gamma coincidence system was also carried out. This work shows in detail the structure of the quality system, the results of the accrediting audit and gives the number of non-conformities detected and of observations made which have all been resolved.

[Sport activity in children and adolescents: temperament and emotional traits]. / L'attività sportiva nel bambino e nell'adolescente: tratti temperamentali ed emozionali.

AIM: Aim of this study is to evaluate anxiety and temperament characteristics in developmental age subjects who practised agonistic sport (individual or team sports) in comparison with a sample group of subjects who practice no agonistic sports. METHODS: Sixty subjects aged from 10 to 16 years were enrolled in the study and divided into 3 groups: 20 subjects practised individual agonistic sport (Group A), 20 subjects practised team agonistic sports (Group B) and 20 subjects who practised non agonistic sport as control group, (Group C). The following tests were used: multidimensional anxiety scale for children (MASC) to evaluate anxiety, EAS scale (Buss e Plomin) to evaluate temperament (emotionability, activity, sociability and shyness for younger children). RESULTS: MASC scale scores underline generalized anxiety with higher significantly score in subjects who practised agonistic sports (Group A and B) compared with Group C. Anxiety symptoms were more evident in subjects who practised individual discipline compared with those who practised team sports. EAS scale indicated that temperament of subjects who practised agonistic sport was characterised by a considerable aptitude for sociability with low emotionability/activity levels in comparison to control group. CONCLUSION: None of the 3 groups showed a psychopathologic profile.

Neuropsychological assessment in children with absence epilepsy.

OBJECTIVE: To define cognitive deficits in children with absence epilepsy. BACKGROUND: Cognitive deficits have often been reported in children with epilepsy, but have rarely been characterized in patients with a specific epileptic syndrome. METHODS: Detailed neuropsychological testing was carried out on 16 right-handed children with absence epilepsy with similar clinical and EEG findings, and the findings were compared to 16 well-matched right-handed children without absence epilepsy. RESULTS: The authors found lower scores of measures of general cognitive functioning and visuospatial skills in patients with absence epilepsy, as compared to controls. Memory disturbances were also detected in absence epilepsy patients, with selective involvement of nonverbal memory and delayed recall. In contrast, verbal memory and language skills were relatively preserved. Patients whose seizures began at an earlier age seemed to have more severe cognitive deficits. CONCLUSION: Language skills tend to be relatively well preserved in children with generalized epilepsy, with more dysfunction seen in global terms rather than specific lateralizing deficits. Patients with absence epilepsy seem to show a similar neurocognitive profile that may be a reflection of the underlying epilepsy syndrome.

Disk caching with an optical ring.

We propose a simple extension to the optical network of a scalable multiprocessor that optimizes page swap outs. More specifically, we propose to extend the network with an optical ring that not only transfers swapped-out pages between the local memories and the disks of the multiprocessor but also acts as a systemwide write cache for these pages. This extended optical network confers several performance benefits: It provides a staging area where swapped-out pages can reside until the disk is free, it increases the possibility of combining several writes to disk, and it acts as a victim cache for pages that are swapped out and subsequently accessed by the same or a different processor. To evaluate the extent to which these benefits affect performance, we use detailed execution-driven simulations of several out-of-core parallel applications that run on an eight-node scalable multiprocessor. Our results demonstrate that our optical ring provides consistent performance improvements that derive mostly from faster page swap outs and victim caching. To show that our optical ring can also be applied successfully to traditional multiprocessors in which processors are interconnected with electronic networks, we evaluate its benefits for a mesh-connected multiprocessor. This latter evaluation shows that our optical ring improves performance for a traditional multiprocessor by roughly the same amount as it does for an optically interconnected multiprocessor. On the basis of these results and our parameter-space study our main conclusion is that our optical ring is highly efficient under several architectural assumptions and for most out-of-core parallel applications. Even though our study focuses on optimizing page swap outs, we believe that caching data with an optical ring can be beneficial for other types of disk-write traffic as well.