Exosomes mediate the cytoprotective action of mesenchymal stromal cells on hypoxia-induced pulmonary hypertension

BACKGROUND

Hypoxia induces an inflammatory response in the lung manifested by alternative activation of macrophages with elevation of proinflammatory mediators that are critical for the later development of hypoxic pulmonary hypertension. Mesenchymal stromal cell transplantation inhibits lung inflammation, vascular remodeling, and right heart failure and reverses hypoxic pulmonary hypertension in experimental models of disease. In this study, we aimed to investigate the paracrine mechanisms by which mesenchymal stromal cells are protective in hypoxic pulmonary hypertension.

METHODS AND RESULTS

We fractionated mouse mesenchymal stromal cell-conditioned media to identify the biologically active component affecting in vivo hypoxic signaling and determined that exosomes, secreted membrane microvesicles, suppressed the hypoxic pulmonary influx of macrophages and the induction of proinflammatory and proproliferative mediators, including monocyte chemoattractant protein-1 and hypoxia-inducible mitogenic factor, in the murine model of hypoxic pulmonary hypertension. Intravenous delivery of mesenchymal stromal cell-derived exosomes (MEX) inhibited vascular remodeling and hypoxic pulmonary hypertension, whereas MEX-depleted media or fibroblast-derived exosomes had no effect. MEX suppressed the hypoxic activation of signal transducer and activator of transcription 3 (STAT3) and the upregulation of the miR-17 superfamily of microRNA clusters, whereas it increased lung levels of miR-204, a key microRNA, the expression of which is decreased in human pulmonary hypertension. MEX produced by human umbilical cord mesenchymal stromal cells inhibited STAT3 signaling in isolated human pulmonary artery endothelial cells, demonstrating a direct effect of MEX on hypoxic vascular cells.

CONCLUSION

This study indicates that MEX exert a pleiotropic protective effect on the lung and inhibit pulmonary hypertension through suppression of hyperproliferative pathways, including STAT3-mediated signaling induced by hypoxia.

Bone marrow stromal cells attenuate lung injury in a murine model of neonatal chronic lung disease

RATIONALE

Neonatal chronic lung disease, known as bronchopulmonary dysplasia (BPD), remains a serious complication of prematurity despite advances in the treatment of extremely low birth weight infants.

OBJECTIVES

Given the reported protective actions of bone marrow stromal cells (BMSCs; mesenchymal stem cells) in models of lung and cardiovascular injury, we tested their therapeutic potential in a murine model of BPD.

METHODS

Neonatal mice exposed to hyperoxia (75% O(2)) were injected intravenously on Day 4 with either BMSCs or BMSC-conditioned media (CM) and assessed on Day 14 for lung morphometry, vascular changes associated with pulmonary hypertension, and lung cytokine profile.

MEASUREMENTS AND MAIN RESULTS

Injection of BMSCs but not pulmonary artery smooth muscle cells (PASMCs) reduced alveolar loss and lung inflammation, and prevented pulmonary hypertension. Although more donor BMSCs engrafted in hyperoxic lungs compared with normoxic controls, the overall low numbers suggest protective mechanisms other than direct tissue repair. Injection of BMSC-CM had a more pronounced effect than BMSCs, preventing both vessel remodeling and alveolar injury. Treated animals had normal alveolar numbers at Day 14 of hyperoxia and a drastically reduced lung neutrophil and macrophage accumulation compared with PASMC-CM-treated controls. Macrophage stimulating factor 1 and osteopontin, both present at high levels in BMSC-CM, may be involved in this immunomodulation.

CONCLUSIONS

BMSCs act in a paracrine manner via the release of immunomodulatory factors to ameliorate the parenchymal and vascular injury of BPD in vivo. Our study suggests that BMSCs and factor(s) they secrete offer new therapeutic approaches for lung diseases currently lacking effective treatment.

Potassium channel KIR4.1 as an immune target in multiple sclerosis

BACKGROUND

Multiple sclerosis is a chronic inflammatory demyelinating disease of the central nervous system. Many findings suggest that the disease has an autoimmune pathogenesis; the target of the immune response is not yet known.

METHODS

We screened serum IgG from persons with multiple sclerosis to identify antibodies that are capable of binding to brain tissue and observed specific binding of IgG to glial cells in a subgroup of patients. Using a proteomic approach focusing on membrane proteins, we identified the ATP-sensitive inward rectifying potassium channel KIR4.1 as the target of the IgG antibodies. We used a multifaceted validation strategy to confirm KIR4.1 as a target of the autoantibody response in multiple sclerosis and to show its potential pathogenicity in vivo.

RESULTS

Serum levels of antibodies to KIR4.1 were higher in persons with multiple sclerosis than in persons with other neurologic diseases and healthy donors (P<0.001 for both comparisons). We replicated this finding in two independent groups of persons with multiple sclerosis or other neurologic diseases (P<0.001 for both comparisons). Analysis of the combined data sets indicated the presence of serum antibodies to KIR4.1 in 186 of 397 persons with multiple sclerosis (46.9%), in 3 of 329 persons with other neurologic diseases (0.9%), and in none of the 59 healthy donors. These antibodies bound to the first extracellular loop of KIR4.1. Injection of KIR4.1 serum IgG into the cisternae magnae of mice led to a profound loss of KIR4.1 expression, altered expression of glial fibrillary acidic protein in astrocytes, and activation of the complement cascade at sites of KIR4.1 expression in the cerebellum.

CONCLUSIONS

KIR4.1 is a target of the autoantibody response in a subgroup of persons with multiple sclerosis. (Funded by the German Ministry for Education and Research and Deutsche Forschungsgemeinschaft.).

Antibodies to native myelin oligodendrocyte glycoprotein in children with inflammatory demyelinating central nervous system disease

OBJECTIVE

Myelin oligodendrocyte glycoprotein (MOG) is a candidate target antigen in demyelinating diseases of the central nervous system (CNS). Although MOG is encephalitogenic in different animal models, the relevance of this antigen in human autoimmune diseases of the CNS is still controversial.

METHODS

We investigated the occurrence and biological activity of antibodies to native MOG (nMOG) in 47 children during a first episode of CNS demyelination (acute disseminated encephalomyelitis [ADEM], n = 19 and clinical isolated syndrome [CIS], n = 28) by a cell-based bioassay.

RESULTS

High serum immunoglobulin G (IgG) titers to nMOG were detected in 40% of children with CIS/ADEM but 0% of the control children affected by other neurological diseases, healthy children, or adults with inflammatory demyelinating diseases, respectively. By contrast, IgM antibodies to nMOG occurred in only 3 children affected by ADEM. Children with high anti-nMOG IgG titer were significantly younger than those with low IgG titer. Anti-nMOG IgG titers did not differ between the ADEM and CIS group, and did not predict conversion from CIS to MS during a mean 2-year follow-up. However, intrathecal IgG anti-MOG antibody synthesis was only seen in CIS children. IgG antibodies to nMOG not only bound to the extracellular domain of nMOG, but also induced natural killer cell-mediated killing of nMOG-expressing cells in vitro.

INTERPRETATION

Overall, these findings suggest nMOG as a major target of the humoral immune response in a subgroup of children affected by inflammatory demyelinating diseases of the CNS. Children may provide valuable insight into the earliest immune mechanisms of CNS demyelination.

Bronchioalveolar stem cells increase after mesenchymal stromal cell treatment in a mouse model of bronchopulmonary dysplasia

Bronchopulmonary dysplasia (BPD) remains a major complication of prematurity resulting in significant morbidity and mortality. The pathology of BPD is multifactorial and leads to alveolar simplification and distal lung injury. Previous studies have shown a beneficial effect of systemic treatment with bone marrow-derived mesenchymal stromal cells (MSCs) and MSC-conditioned media (MSC-CM) leading to amelioration of the lung parenchymal and vascular injury in vivo in the hyperoxia murine model of BPD. It is possible that the beneficial response from the MSCs is at least in part due to activation of endogenous lung epithelial stem cells. Bronchioalveolar stem cells (BASCs) are an adult lung stem cell population capable of self-renewal and differentiation in culture, and BASCs proliferate in response to bronchiolar and alveolar lung injury in vivo. Systemic treatment of neonatal hyperoxia-exposed mice with MSCs or MSC-CM led to a significant increase in BASCs compared with untreated controls. Treatment of BASCs with MSC-CM in culture showed an increase in growth efficiency, indicating a direct effect of MSCs on BASCs. Lineage tracing data in bleomycin-treated adult mice showed that Clara cell secretory protein-expressing cells including BASCs are capable of contributing to alveolar repair after lung injury. MSCs and MSC-derived factors may stimulate BASCs to play a role in the repair of alveolar lung injury found in BPD and in the restoration of distal lung cell epithelia. This work highlights the potential important role of endogenous lung stem cells in the repair of chronic lung diseases.

Mesenchymal stem cell-mediated reversal of bronchopulmonary dysplasia and associated pulmonary hypertension

Clinical trials have failed to demonstrate an effective preventative or therapeutic strategy for bronchopulmonary dysplasia (BPD), a multifactorial chronic lung disease in preterm infants frequently complicated by pulmonary hypertension (PH). Mesenchymal stem cells (MSCs) and their secreted components have been shown to prevent BPD and pulmonary fibrosis in rodent models. We hypothesized that treatment with conditioned media (CM) from cultured mouse bone marrow-derived MSCs could reverse hyperoxia-induced BPD and PH. Newborn mice were exposed to hyperoxia (FiO₂=0.75) for two weeks, were then treated with one intravenous dose of CM from either MSCs or primary mouse lung fibroblasts (MLFs), and placed in room air for two to four weeks. Histological analysis of lungs harvested at four weeks of age was performed to determine the degree of alveolar injury, blood vessel number, and vascular remodeling. At age six weeks, pulmonary artery pressure (PA acceleration time) and right ventricular hypertrophy (RVH; RV wall thickness) were assessed by echocardiography, and pulmonary function tests were conducted. When compared to MLF-CM, a single dose of MSC-CM-treatment (1) reversed the hyperoxia-induced parenchymal fibrosis and peripheral PA devascularization (pruning), (2) partially reversed alveolar injury, (3) normalized lung function (airway resistance, dynamic lung compliance), (4) fully reversed the moderate PH and RVH, and (5) attenuated peripheral PA muscularization associated with hyperoxia-induced BPD. Reversal of key features of hyperoxia-induced BPD and its long-term adverse effects on lung function can be achieved by a single intravenous dose of MSC-CM, thereby pointing toward a new therapeutic intervention for chronic lung diseases.

Iron oxide nanorods as high-performance magnetic resonance imaging contrast agents

An efficient magnetic resonance imaging (MRI) contrast agent with a high R2 relaxivity value is achieved by controlling the shape of iron oxide to rod like morphology with a length of 30-70 nm and diameter of 4-12 nm. Fe3O4 nanorods of 70 nm length, encapsulated with polyethyleneimine show a very high R2 relaxivity value of 608 mM(-1) s(-1). The enhanced MRI contrast of nanorods is attributed to their higher surface area and anisotropic morphology. The higher surface area induces a stronger magnetic field perturbation over a larger volume more effectively for the outer sphere protons. The shape anisotropy contribution is understood by calculating the local magnetic field of nanorods and spherical nanoparticles under an applied magnetic field (3 Tesla). As compared to spherical geometry, the induced magnetic field of a rod is stronger and hence the stronger magnetic field over a large volume leads to a higher R2 relaxivity of nanorods.

Changing trends in presentation, diagnosis and management of renal angiomyolipoma: comparison of sporadic and tuberous sclerosis complex-associated forms

OBJECTIVES

To evaluate the changing management of sporadic renal angiomyolipoma and renal angiomyolipoma associated with the tuberous sclerosis complex (TSC) during the past 16 years.

METHODS

We retrospectively reviewed the charts of 60 patients with angiomyolipoma seen at our institutions.

RESULTS

The median age at presentation was 45 years (range 7-78). The presentation was pain in 30 patients and hematuria in 13; it was incidentally discovered in 17 patients. Of the 60 patients, 43 were females. TSC was present in 14 patients. The median tumor size was 4 cm (range 0.3-40, mean 6.5 +/- 1.1). Of the 60 patients, 31 were followed up expectantly. Surgery or intervention was needed for 29 patients to control hemorrhage or relieve pain or because of the suspicion of malignancy. Of these 29 patients, 12 underwent nephrectomy, 11 partial nephrectomy, and 6 embolization. The patients treated for hemorrhage had a median tumor diameter of 11 cm (range 2-21). Patients were followed up for a mean of 39.3 +/- 5.4 months. The lesions grew an average of 4.7 +/- 3.4 cm for TSC tumors and 0.6 +/- 0.2 cm for sporadic angiomyolipoma tumors. None of the patients developed renal impairment. Patients with TSC presented at a younger age, had larger and bilateral lesions, and were more symptomatic during follow-up. In the past 6 years, a significant trend was seen toward finding tumors in asymptomatic patients and toward the use of conservative or interventional (embolization) treatment.

CONCLUSIONS

Renal angiomyolipoma has a slow growth rate. The preservation of renal function was noted in all our patients. A recent shift was noted toward finding smaller tumors in asymptomatic patients and the use of conservative and interventional treatment.

Folded-back solution structure of monomeric factor H of human complement by synchrotron X-ray and neutron scattering, analytical ultracentrifugation and constrained molecular modelling

Factor H (FH) is a regulatory cofactor for the protease factor I in the breakdown of C3b in the complement system of immune defence, and binds to heparin and other polyanionic substrates. FH is composed of 20 short consensus/complement repeat (SCR) domains, for which the overall arrangement in solution is unknown. As previous studies had shown that FH can form monomeric or dimeric structures, X-ray and neutron scattering was accordingly performed with FH in the concentration range between 0.7 and 14 mg ml(-1). The radius of gyration of FH was determined to be 11.1-11.3 nm by both methods, and the radii of gyration of the cross-section were 4.4 nm and 1.7 nm. The distance distribution function P(r) showed that the overall length of FH was 38 nm. The neutron data showed that FH was monomeric with a molecular mass of 165,000(+/-17,000) Da. Analytical ultracentrifugation data confirmed this, where sedimentation equilibrium curve fits gave a mean molecular mass of 155,000(+/-3,000) Da. Sedimentation velocity experiments using the g*(s) derivative method showed that FH was monodisperse and had a sedimentation coefficient of 5.3(+/-0.1) S. In order to construct a full model of FH for scattering curve and sedimentation coefficient fits, homology models were constructed for 17 of the 20 SCR domains using knowledge of the NMR structures for FH SCR-5, SCR-15 and SCR-16, and vaccinia coat protein SCR-3 and SCR-4. Molecular dynamics simulations were used to generate a large conformational library for each of the 19 SCR-SCR linker peptides. Peptides from these libraries were combined with the 20 SCR structures in order to generate stereochemically complete models for the FH structure. Using an automated constrained fit procedure, the analysis of 16,752 possible FH models showed that only those models in which the 20 SCR domains were bent back upon themselves were able to account for the scattering and sedimentation data. The best-fit models showed that FH had an overall length of 38 nm and is flexible. This length is significantly less than a predicted length of 73 nm if the 20 SCR structures had been arranged in an extended arrangement. This outcome is attributed to several long linker sequences. These bent-back domain structures may correspond to conformational flexibility in FH and enable the multiple FH binding sites for C3 and heparin to come into close proximity.

Infrared optoelectronic volumetry, the ideal way to measure limb volume

OBJECTIVES

The aim of the study was to compare a novel infrared optoelectronic system (Perometer) of limb volume measurement with water displacement and two indirect measurement techniques.

DESIGN

A prospective experimental study.

METHODS

In 10 healthy male volunteers (20 limbs) we compared limb volume measurements obtained by water displacement, infrared perometry, the disc model method and the frustrum method. In a further 17 patients with swollen limbs due to lymphatic (9 limbs) or venous (11 limbs) disease, perometry was compared to the disc model method and the frustrum method only.

RESULTS

In normal limbs, mean +/- S.D. limb volume using water displacement was 1802 +/- 268 ml. Perometer values agreed almost exactly (1809 +/- 262 ml, r = 0.97, variation +/- 7% by limits of agreement) but both the disc (1923 +/- 306 ml, r = 0.90, variation +/- 14%) and frustrum (1905 +/- 372 ml, r = 0.72, variation +/- 28%) methods significantly overestimated limb volumes (p < 0.05 (ANOVA, Fisher's Least Significant Difference)). In diseased limbs perometer, disc method and frustrum method results were 2415 +/- 995 ml, 2494 +/- 969 ml, and 2413 +/- 870 ml representing variation of +/- 17% and +/- 23% for disc method and frustrum method respectively compared to perometry.

CONCLUSIONS

Perometry is a novel, extremely accurate and easy method for assessing limb volume. It provides more accurate results than traditional indirect measurement of limb volume and potentially is a very useful clinical and research tool.

Physical and pH properties of gastroesophagopharyngeal refluxate: a 24-hour simultaneous ambulatory impedance and pH monitoring study

OBJECTIVES

Frequency occurrence of nonacidic and nonliquid reflux events in the pharynx has not been systematically studied. The aim of the present study was to characterize the physical (liquid, gas, and mixed gas/liquid) and pH properties of the gastroesophagopharyngeal refluxate.

METHODS

We performed a total of 31 24-h simultaneous ambulatory pharyngoesophageal impedance and pH recordings in 11 GERD patients, 10 patients with reflux-attributed laryngitis, and 10 healthy controls.

RESULTS

On average, the total number of reflux events (all kinds) in the pharynx was less than half of that in the proximal esophagus (18 +/- 4 vs 50 +/- 4, p < 0.01). Most of the pharyngeal reflux events were gas events and were observed in all three studied groups. Prevalence of these gas reflux events ranged between 0 and 74. The number of gas reflux events accompanied by a minor pH drop in laryngitis patients (1 (0-36)) was significantly higher than those in GERD and controls (0 (0-2) and 0 (0-1), respectively, p < 0.05). There was no significant difference in the number of nonacidic gas reflux events among the three groups (GERD: 10 (2-57), laryngitis: 11.5 (0-51), controls: 10.5 (0-27)). Impedance recording identified a total number of 566 events in the pharynx. Of these, a total of 563 events were compatible with gas reflux events, 101 events were accompanied by minor drops in intrapharyngeal pH, whereas 460 events were not accompanied by any pharyngeal pH change.

CONCLUSIONS

Concurrent impedance and pH recordings detect significantly more events qualifying as reflux in the pharynx than pH recordings alone. A substantial majority of these events are gaseous refluxes both with and without minor pH drops. Gas reflux events with weak acidity appear to be more common among patients with reflux-attributed laryngeal lesions compared to GERD patients and controls.

Heavy-metal-induced reactive oxygen species: phytotoxicity and physicochemical changes in plants

As a result of the industrial revolution, anthropogenic activities have enhanced there distribution of many toxic heavy metals from the earth's crust to different environmental compartments. Environmental pollution by toxic heavy metals is increasing worldwide, and poses a rising threat to both the environment and to human health.Plants are exposed to heavy metals from various sources: mining and refining of ores, fertilizer and pesticide applications, battery chemicals, disposal of solid wastes(including sewage sludge), irrigation with wastewater, vehicular exhaust emissions and adjacent industrial activity.Heavy metals induce various morphological, physiological, and biochemical dysfunctions in plants, either directly or indirectly, and cause various damaging effects. The most frequently documented and earliest consequence of heavy metal toxicity in plants cells is the overproduction of ROS. Unlike redox-active metals such as iron and copper, heavy metals (e.g, Pb, Cd, Ni, AI, Mn and Zn) cannot generate ROS directly by participating in biological redox reactions such as Haber Weiss/Fenton reactions. However, these metals induce ROS generation via different indirect mechanisms, such as stimulating the activity of NADPH oxidases, displacing essential cations from specific binding sites of enzymes and inhibiting enzymatic activities from their affinity for -SH groups on the enzyme.Under normal conditions, ROS play several essential roles in regulating the expression of different genes. Reactive oxygen species control numerous processes like the cell cycle, plant growth, abiotic stress responses, systemic signalling, programmed cell death, pathogen defence and development. Enhanced generation of these species from heavy metal toxicity deteriorates the intrinsic antioxidant defense system of cells, and causes oxidative stress. Cells with oxidative stress display various chemical,biological and physiological toxic symptoms as a result of the interaction between ROS and biomolecules. Heavy-metal-induced ROS cause lipid peroxidation, membrane dismantling and damage to DNA, protein and carbohydrates. Plants have very well-organized defense systems, consisting of enzymatic and non-enzymatic antioxidation processes. The primary defense mechanism for heavy metal detoxification is the reduced absorption of these metals into plants or their sequestration in root cells.Secondary heavy metal tolerance mechanisms include activation of antioxidant enzymes and the binding of heavy metals by phytochelatins, glutathione and amino acids. These defense systems work in combination to manage the cascades of oxidative stress and to defend plant cells from the toxic effects of ROS.In this review, we summarized the biochemiCal processes involved in the over production of ROS as an aftermath to heavy metal exposure. We also described the ROS scavenging process that is associated with the antioxidant defense machinery.Despite considerable progress in understanding the biochemistry of ROS overproduction and scavenging, we still lack in-depth studies on the parameters associated with heavy metal exclusion and tolerance capacity of plants. For example, data about the role of glutathione-glutaredoxin-thioredoxin system in ROS detoxification in plant cells are scarce. Moreover, how ROS mediate glutathionylation (redox signalling)is still not completely understood. Similarly, induction of glutathione and phytochelatins under oxidative stress is very well reported, but it is still unexplained that some studied compounds are not involved in the detoxification mechanisms. Moreover,although the role of metal transporters and gene expression is well established for a few metals and plants, much more research is needed. Eventually, when results for more metals and plants are available, the mechanism of the biochemical and genetic basis of heavy metal detoxification in plants will be better understood. Moreover, by using recently developed genetic and biotechnological tools it may be possible to produce plants that have traits desirable for imparting heavy metal tolerance.

Mesenchymal stromal cells expressing heme oxygenase-1 reverse pulmonary hypertension

Pulmonary arterial hypertension (PAH) remains a serious disease, and although current treatments may prolong and improve quality of life, search for novel and effective therapies is warranted. Using genetically modified mouse lines, we tested the ability of bone marrow-derived stromal cells (mesenchymal stem cells [MSCs]) to treat chronic hypoxia-induced PAH. Recipient mice were exposed for 5 weeks to normobaric hypoxia (8%-10% O(2)), MSC preparations were delivered through jugular vein injection and their effect on PAH was assessed after two additional weeks in hypoxia. Donor MSCs derived from wild-type (WT) mice or heme oxygenase-1 (HO-1) null mice (Hmox1(KO)) conferred partial protection from PAH when transplanted into WT or Hmox1(KO) recipients, whereas treatment with MSCs isolated from transgenic mice harboring a human HO-1 transgene under the control of surfactant protein C promoter (SH01 line) reversed established disease in WT recipients. SH01-MSC treatment of Hmox1(KO) animals, which develop right ventricular (RV) infarction under prolonged hypoxia, resulted in normal RV systolic pressure, significant reduction of RV hypertrophy and prevention of RV infarction. Donor MSCs isolated from a bitransgenic mouse line with doxycycline-inducible, lung-specific expression of HO-1 exhibited similar therapeutic efficacy only on doxycycline treatment of the recipients. In vitro experiments indicate that potential mechanisms of MSC action include modulation of hypoxia-induced lung inflammation and inhibition of smooth muscle cell proliferation. Cumulatively, our results demonstrate that MSCs ameliorate chronic hypoxia-induced PAH and their efficacy is highly augmented by lung-specific HO-1 expression in the transplanted cells, suggesting an interplay between HO-1-dependent and HO-1-independent protective pathways.

Recent advances in two-dimensional materials and their nanocomposites in sustainable energy conversion applications

Two-dimensional (2D) materials have a wide platform in research and expanding nano- and atomic-level applications. This study is motivated by the well-established 2D catalysts, which demonstrate high efficiency, selectivity and sustainability exceeding that of classical noble metal catalysts for the oxygen reduction reaction (ORR), oxygen evolution reaction (OER), and/or hydrogen evolution reaction (HER). Nowadays, the hydrogen evolution reaction (HER) in water electrolysis is crucial for the cost-efficient production of a pure hydrogen fuel. We will also discuss another important point related to electrochemical carbon dioxide and nitrogen reduction (ECR and N2RR) in detail. In this review, we mainly focused on the recent progress in the fuel cell technology based on 2D materials, including graphene, transition metal dichalcogenides, black phosphorus, MXenes, metal-organic frameworks, and metal oxide nanosheets. First, the basic attributes of the 2D materials were described, and their fuel cell mechanisms were also summarized. Finally, some effective methods for enhancing the performance of the fuel cells based on 2D materials were also discussed, and the opportunities and challenges of 2D material-based fuel cells at the commercial level were also provided. This review can provide new avenues for 2D materials with properties suitable for fuel cell technology development and related fields.

Anaerobic membrane bioreactors for wastewater treatment: Novel configurations, fouling control and energy considerations

Water shortage, public health and environmental protection are key motives to treat wastewater. The widespread adoption of wastewater as a resource depends upon development of an energy-efficient technology. Anaerobic membrane bioreactor (AnMBR) technology has gained increasing popularity due to their ability to offset the disadvantages of conventional treatment technologies. However there are several hurdles, yet to climb over, for wider spread and scale-up of the technology. This paper reviews fundamental aspects of anaerobic digestion of wastewater, and identifies the challenges and opportunities to the further development of AnMBRs. Membrane fouling and its implications are discussed, and strategies to control membrane fouling are proposed. Novel AnMBR configurations are discussed as an integrated approach to overcome technology limitations. Energy demand and recovery in AnMBRs is analyzed. Finally key issues that require urgent attention to facilitate global penetration of AnMBR technology are highlighted.

Unilateral multicystic dysplastic kidney: long term outcomes

AIMS

To report the long term follow up of children with antenatally detected unilateral multicystic dysplastic kidney (MCDK) with documentation of complications, involution rate with time, and renal function at 10 years.

METHODS

Data were retrieved from a prospective regional registry of patients with MCDK between 1985 and 2004. Children were followed using a common protocol of investigation with follow up ultrasound scans (USS) at 2 (165 patients), 5 (117 patients), and 10 years (43 patients).

RESULTS

Serial USS showed that 33% of the MCDK kidneys had completely involuted at 2 years of age, 47% at 5 years, and 59% at 10 years. No patients developed hypertension, significant proteinuria, or malignancy, but two developed pelviureteric junction obstruction in the contralateral kidney. Twenty seven of 143 children (19%) had vesicoureteric reflux (VUR) (96% mild to moderate VUR) into the contralateral kidney with no difference in the incidence of urinary tract infections or renal scarring between those with or without VUR. The mean estimated glomerular filtration rate (GFR) was 86.4 ml/min/1.73 m2 (range 48-125) in 31 of 43 patients followed to 10 years.

CONCLUSIONS

Conservative management of unilateral MCDK is justified with clinical review and infrequent USS but longer term follow up continues in the 41% still with renal remnants at 10 years and those with impaired GFR. It is suggested that the initial micturating cystogram is deferred unless abnormal USS features are present in the contralateral kidney or ureter.

Potential Use of Seaweed Bioactive Compounds in Skincare-A Review

Modern lifestyles have developed new attention on appearance and personal care which attract a huge number of consumers towards cosmetic products. The demand for a skincare product with natural ingredients is rapidly increasing. Seaweeds are major resources for in-demand active compounds with a wide variety of applications. The use of seaweed-derived ingredients in cosmetic products has increased in recent years as many scientific studies have proved the potential skincare properties of seaweed bioactive compounds. This review emphasizes possible skincare properties of seaweed bioactive compounds. The review outlines the mechanism involved in skin problems including hyperpigmentation, premature skin aging, and acne in the first part while the second part focuses on the promising application of seaweeds in skin protection by highlighting the bioactive compound responsible for their bioactivity.

Efficacy of esophageal impedance/pH monitoring in patients with refractory gastroesophageal reflux disease, on and off therapy

BACKGROUND & AIMS

Intraluminal impedance monitoring has given new dimensions to the diagnosis of reflux disease. However, there is no defined algorithm for evaluating refractory reflux symptoms. We studied whether combined impedance/pH monitoring in patients on therapy can predict acid reflux in patients off therapy and whether testing should be carried out when patients are on or off therapy.

METHODS

Thirty-nine adults (mean age, 50 years; 24 female) with refractory reflux symptoms were evaluated by impedance/pH monitoring while on therapy, followed by wireless pH monitoring while off therapy. Non-acid reflux events in patients on therapy were correlated with acid reflux parameters studied off therapy. In addition, the likelihood of test abnormalities on and off therapy was determined.

RESULTS

In 25 of 39 patients (64%) on therapy, impedance testing was normal, with a median of 69 events (interquartile, 63.0-78.0). The percentage of time at pH <4 was within the normal range for all patients who were on therapy. The pH test results were abnormal in 28 of 39 patients (72%) when studied off therapy. Ninety-three of patients with abnormal impedance on therapy also had abnormal acid reflux off therapy. When both groups were off therapy, the patients with abnormal impedance parameters on therapy had significantly higher median (interquartile) 2-day baseline levels of esophageal acid exposure (8.7%, 6.9%-12.5%), compared with those of patients with normal impedance parameters while on therapy (6.0%, 2.8%-9.4%; P = .026).

CONCLUSIONS

Abnormal impedance in patients on therapy predicts acid reflux in patients off therapy. In patients with refractory reflux, combined impedance/pH monitoring might provide the single best strategy for evaluation of reflux symptoms.

Silica encapsulation and magnetic properties of FePt nanoparticles

Core-shell nanoparticles have emerged as an important class of functional nanostructures with potential applications in many diverse fields, especially in health sciences. We have used a modified aqueous sol-gel route for the synthesis of size-selective FePt@SiO2 core-shell nanoparticles. In this approach, oleic acid and olyel amine stabilized FePt nanoparticles are first encapsulated through an aminopropoxysilane (APS) monolayer and then subsequent condensation of triethoxysilane (TEOS) on FePt particle surface. These well-defined FePt@SiO2 core-shell nanoparticles with narrow size distribution become colloidal in aqueous media, and can thus be used as carrier fluid for biomolecular complexes. In comparison, the scarce hydrophilic nature of oleic acid monolayers on FePt particle surface yields an edgy partial coating of silica when only TEOS is applied for the surface modification. The synthesized core-shell nanoparticles were characterized by direct techniques of high resolution transmission electron microscopy (HRTEM), EDS and indirectly via UV-vis absorption and FTIR studies. The FePt@SiO2 nanoparticles exhibit essential characteristics of superparamagnetic behavior, as investigated by SQUID magnetometry. The blocking temperatures (T(B)) of FePt and FePt@SiO2 (135 and 80 K) were studied using zero field cooled (ZFC)/field cooled (FC) curves.

Pre-operative Radial Arterial Diameter Predicts Early Failure of Arteriovenous Fistula (AVF) for Haemodialysis

INTRODUCTION

Long term patency of arteriovenous fistula (AVF) is relevant to the management of end stage renal failure (ESRF) patients on haemodialysis (HD). We evaluated the role of routine radial arterial duplex for imaging radial artery before AVF formation to investigate the relationaship between radial artery internal diameter (ID) and AVF patency.

METHODS

21 patients with ESRF were examined by duplex sonography before AVF formation, 1 day, 1 week, 4 week and 12 weeks post AVF formation. For assessment of AVF patency, patients were divided into 2 groups. Group-1, 11 patients with radial artery ID <1.5mm and Group-2, 10 patients with radial artery ID >1.5mm. Measurement of radial artery blood inflow rate was calculated from mean blood flow velocity and vessel diameter. All AVFs were constructed on the forearm using autologous veins.

RESULTS

In Group-1, 5 patients (45%) showed immediate thrombosis of AVF graft. All patients in group-2 had patent AVF at 12 weeks. Pre-AVF formation radial artery blood inflow rate between two groups was not significantly different (p=0.06). Radial artery blood inflow rate was consistently and significantly higher in group-2 at all later time points with p value of <0.01 (Mann Whitney test).

CONCLUSION

There was a high failure rate of AVF with radial artery ID of <1.5mm. In the presence of small radial arteries primary access AVF in the upper arm should be considered.

Recent progress in integrated fixed-film activated sludge process for wastewater treatment: A review

Integrated fixed-film activated sludge (IFAS) process is considered as one of the leading-edge processes that provides a sustainable solution for wastewater treatment. IFAS was introduced as an advancement of the moving bed biofilm reactor by integrating the attached and the suspended growth systems. IFAS offers advantages over the conventional activated sludge process such as reduced footprint, enhanced nutrient removal, complete nitrification, longer solids retention time and better removal of anthropogenic composites. IFAS has been recognized as an attractive option as stated from the results of many pilot and full scales studies. Generally, IFAS achieves >90% removals for combined chemical oxygen demand and ammonia, improves sludge settling properties and enhances operational stability. Recently developed IFAS reactors incorporate frameworks for either methane production, energy generation through algae, or microbial fuel cells. This review details the recent development in IFAS with the focus on the pilot and full-scale applications. The microbial community analyses of IFAS biofilm and floc are underlined along with the special emphasis on organics and nitrogen removals, as well as the future research perspectives.

Synthesis, Characterization, and Sunlight Mediated Photocatalytic Activity of CuO Coated ZnO for the Removal of Nitrophenols

CuO@ZnO core-shell catalysts, coated by varying the CuO layer density ranging from 0.5% to 10%, were synthesized with the aim to enhance the photocatalytic activity of ZnO in sunlight and control its photocorrosion. Initially, the Cu(2+) ions were impregnated on presynthesized ZnO by wet impregnation and finally converted to CuO layers by calcination. The optical and structural characterization of the synthesized powders was performed by DRS, PL, Raman spectroscopy, and XRD analysis, respectively. The homogeneity of the coated layers was explored by FESEM. The photocatalytic activity of CuO coated ZnO was investigated for the degradation of mononitrophenols (2-, 3-, and 4-nitrophenol) and dinitrophenols (2,4-, 2,5-, and 2,6-dinitrophenol) in the exposure of the complete spectrum and visible region (420-800 nm) of sunlight. The effect of the increasing density coated layers of CuO on photocatalytic activity was evaluated for the degradation of 4-NP. Compared to pristine ZnO, a substantial increase in the degradation/mineralization ability was observable for the catalysts coated with 0.5% and 1% CuO, whereas a detrimental effect was noticed for higher coating density. Prior to photocatalytic studies, as evaluated by cyclic voltammetry (CV), compared to pure ZnO, a significant suppression of photocorrosion was noticed, under illumination, for catalysts coated with lower CuO coating. The progress of the photocatalytic degradation process was monitored by HPLC while the mineralization ability of the synthesized catalysts was estimated by TOC. The estimation of the released ions and their further interaction with the excited states and the reactive oxygen was monitored by ion chromatography (IC).