Stalled cerebral capillary blood flow in mouse models of essential thrombocythemia and polycythemia vera revealed by in vivo two-photon imaging.

BACKGROUND: Essential thrombocythemia (ET) and polycythemia vera (PV) are myeloproliferative neoplasms (MPNs) that share the JAK2(V617F) mutation in hematopoietic stem cells, leading to excessive production of predominantly platelets in ET, and predominantly red blood cells (RBCs) in PV. The major cause of morbidity and mortality in PV and ET is thrombosis, including cerebrovascular occlusive disease. OBJECTIVES: To identify the effect of excessive blood cells on cerebral microcirculation in ET and PV. METHODS: We used two-photon excited fluorescence microscopy to examine cerebral blood flow in transgenic mouse models that mimic MPNs. RESULTS AND CONCLUSIONS: We found that flow was 'stalled' in an elevated fraction of brain capillaries in ET (18%), PV (27%), mixed MPN (14%) and secondary (non-MPN) erythrocytosis (27%) mice, as compared with controls (3%). The fraction of capillaries with stalled flow increased when the hematocrit value exceeded 55% in PV mice, and the majority of stalled vessels contained only stationary RBCs. In contrast, the majority of stalls in ET mice were caused by platelet aggregates. Stalls had a median persistence time of 0.5 and 1 h in ET and PV mice, respectively. Our findings shed new light on potential mechanisms of neurological problems in patients with MPNs.

The effect of intermittent operation on a wind-powered membrane system for brackish water desalination.

Renewable energy powered membrane systems that are directly-connected must take account of both the inherent fluctuations and the intermittency of the energy resource. In order to determine the effect of intermittent operation, a membrane system was tested with variables of (i) amplitude from 60 to 300 W and (ii) length of time with no power from 0.5 to 3 min. This was performed over one hour periods with six on/off cycles to simulate the system operating under intermittent operation for short periods of time when directly-connected to a small wind turbine. The setup used a Filmtec BW30-4040 brackish water reverse osmosis membrane with feed waters of 2,750 mg/L and 5,500 mg/L NaCl. The results showed that the membrane system produced potable water under the majority of intermittency experiments performed. There was a relatively large increase in the average salt concentration of the permeate, especially when the system was off for shorter periods of time (0.5-1 min). Longer periods of no power (1-3 min) did not have as significant an effect on the average water quality. This is important when the need for energy buffering or short term storage is considered for these systems as it shows the potential for improving the overall flux and water quality using temporary energy storage.

Renewable energy powered membrane technology. 2. The effect of energy fluctuations on performance of a photovoltaic hybrid membrane system.

This paper reports on the performance fluctuations during the operation of a batteryless hybrid ultrafiltration--nanofiltration/reverse osmosis (UF-NF/RO) membrane desalination system powered by photovoltaics treating brackish groundwater in outback Australia. The renewable energy powered membrane (RE-membrane) system is designed to supply clean drinking water to a remote community of about 50 inhabitants. The performance of the RE-membrane system over four different solar days is summarized using four different NF membranes (BW30, NF90, ESPA4, TFC-S), and examined in more detail for the BW30 membrane. On an Australian spring day, the system produced 1.1 m3 of permeate with an average conductivity of 0.28 mS x cm(-1), recovering 28% of the brackish (8.29 mS x cm(-1) conductivity) feedwater with an average specific energy consumption of 2.3 kWh x m(-3). The RE-membrane system tolerated large fluctuations in solar irradiance (500--1200 W x m(-2)), resulting in only small increases in the permeate conductivity. When equipped with the NF90 (cloudy day) and ESPA4 (rainy day) membranes, the system was still able to produce 1.36 m(-3) and 0.85 m(-3) of good quality permeate, respectively. The TFC-S membrane was not able to produce adequate water quality from the bore water tested. It is concluded that batteryless operation is a simple and robust way to operate such systems under conditions ranging from clear skies to medium cloud cover.

Renewable energy powered membrane technology. 1. Development and characterization of a photovoltaic hybrid membrane system.

In isolated communities where potable water sources as well as energy grids are limited or nonexistent, treating brackish groundwater aquifers with small-scale desalination systems can be a viable alternative to existing water infrastructures. Given the unavailability of power in many such situations, renewable energy is an obvious solution to power such systems. However, renewable energy is an intermittent power supply and with regards to the performance of intermittently operated desalination systems, only very limited experience exists, both with regards to efficiency as well as water quality. In this paper, this lack of knowledge is addressed by evaluating a system operated with varying parameters (pressure and flow) with constant power as a step toward defining a safe operating window, and they provide a basis for interpreting future data obtained with a renewable energy source. Field trials were performed on a brackish (5300 mg/L TDS; 8290 microS/cm) bore in Central Australia with a photovoltaic-powered membrane filtration (PV-membrane) system. Four nanofiltration and reverse osmosis membranes (BW30, ESPA4, NF90, TFC-S) and a number of operation parameter combinations (transmembrane pressure, feed flow, TFC-S) and operating parameters transmembrane pressure and feed flow were investigated to find the best operating conditions for maximum drinking water production and minimum specific energy consumption (SEC). The ESPA4 membrane performed best for this brackish source, producing 250 L/h of excellent drinking water (257 mg/L TDS; 400 microS/ cm) at an SEC of 1.2 kWh/m3. The issue of brine disposal or reuse is also discussed and the article compares the salinity of the produced brine with livestock water. Since the feedwater is disinfected physically using ultrafiltration (UF), the brine is free from bacteria and most viruses and hence can be seen more as a reusable product stream than a waste stream with a disposal problem.

Steroid estrogens in primary and tertiary wastewater treatment plants.

The concentrations of two natural estrogens (estrone (E1) and Estradiol (E2)) and one synthetic progestin (Ethinylestradiol (EE2)) were measured for different unit operations in an advanced sewage treatment plant and in a large coastal enhanced primary sewage treatment plant. The average influent concentration to both plants was similar: 55 and 53 ng/L for E1 and 22 and 12 ng/L for E2 for the advanced and enhanced primary STPs, respectively. The activated sludge process at the advanced STP removed up to 85% and 96% of E1 and E2, respectively. The enhanced primary sewage treatment plant was mostly ineffective at removing the steroids with only 14% of E1 and 5% of E2 being removed during the treatment process. EE2 was not been detected during the study period in the influent or effluent of either STP. The difference in the observed removal between the two plants is primarily linked to plant performance but the extent to which removal of steroid estrogens is due to bacterial metabolism (i.e. the advanced STP) rather than adsorption to the bacterial biomass remains unclear. The poor removal observed for the coastal enhanced primary STP may have implications for the receiving environment in terms of a greater potential for abnormal reproductive systems in marine animals, particularly if discharges are into large bays or harbours where flushing is limited.

Predicting fate of the contraceptive pill in wastewater treatment and discharge.

The risk of endocrine disrupters to humans and wildlife is to date poorly understood, although evidence of effects is now widespread. In understanding the risk, an important step is the determination of the partitioning, as well as chemical and biochemical transformation, of compounds in the environment, the water cycle and the food chain. This is a complex task and this paper is a first step towards estimating some of these factors from a largely theoretical approach. A chemical fate model is used to predict the fate of the contraceptive drug 17alpha-ethinylestradiol (EE2). The example of the contraceptive pill is chosen to follow the journey of the drug from human ingestion and excretion to treatment in a sewage treatment plant (STP) using fugacity-based fate models, followed by discharge into a receiving river and eventually into the estuary/sea. The model predicts how EE2 will partition into the different compartments during each stage of this journey and thereby infiltrate into the food chain. The results suggest that a person would have to ingest more than 30,000 portions of fish to consume an equivalent to a single average dose of the contraceptive pill. While this scenario is highly unlikely, the biochemical consequence of the contraceptive pill is greatly significant. Furthermore, there are many identified similarly estrogenic compounds in the environment while this study only considers one. Cumulative effects of such compounds as well as degradation into other potent compounds may be anticipated. An important message in this paper is the interrelation of wastewater effluent discharge and eventual human exposure of marginally degradable and lipophilic chemicals. While at present the main concerns regarding endocrine disrupters appear to be the fear of their occurrence in drinking water sources, it is clear that the domains of wastewater treatment and discharge, water supply and contamination of food should not be treated as separate issues. The model suggests that exposure from food (contaminated by effluent) may be much more significant than from drinking water.

Local administration of carbon monoxide inhibits neointima formation in balloon injured rat carotid arteries.

Recent studies indicate that systemic induction of heme oxygenase-1 (HO-1), which oxidatively degrades heme into iron, biliverdin, and carbon monoxide (CO), or adenoviral-mediated gene transfer of HO-1 inhibits neointima formation after experimental vascular injury. In the present study, we investigated whether the acute, local administration of the HO-1 product, CO, regulates the arterial remodeling response following injury. Immediately after balloon injury of rat carotid arteries, a saturated solution of CO or nitrogen (N2), or phosphate buffered saline (PBS) was incubated luminally within the injured vessels for 30 min. Two weeks after injury, arteries exposed to CO exhibited significantly reduced neointimal area, neointimal area/medial wall area ratio, neointimal thickness, and medial wall area compared to arteries exposed to N2 or PBS. Arteries exposed to CO also demonstrated significantly reduced DNA synthesis in the medial wall two days after injury as suggested by proliferating cell nuclear antigen immunostaining, and this was associated with a decrease in the protein expression of the G1 cyclins, cyclin E and A, and transforming growth factor-beta1. These results indicate that the acute, local delivery of CO blocks the pathophysiological remodeling response to vascular injury, and identifies CO as a potentially important therapeutic agent in the treatment of vasculoproliferative disease.

Steroid estrogens in ocean sediments.

This paper gives results from a study measuring the abundance of steroid hormones in ocean sediments in the proximity of a deep ocean sewage outfall. The outfall is discharge point for an enhanced primary sewage treatment plant and sediment samples were taken adjacent and 7 km from the outfall. All samples contained steroid estrogens at nanogram per gram levels with higher concentrations at the 7 km sampling site. The concentration of estrone ranged from (0.16-1.17 ng/g), 17beta-estradiol (0.22-2.48 ng/g) and the synthetic 17alpha-ethinylestradiol (<0.05-0.5 ng/g). The values detected correspond with estimates based on the proportion of estrogens sorbed to particles in the effluent and the expected proportion of particles originating from sewage in the ocean sediments. The results suggest that estrogens associated with the particulate fraction aggregate on contact with high ionic strength seawater and settle to the seafloor after discharge through deep ocean outfalls.

Removal of hormones and pharmaceuticals in the Advanced Water Recycling Demonstration Plant in Queensland, Australia.

An advanced water recycling demonstration plant was employed to investigate the effectiveness of a number of treatment technologies in the removal of some residuals of commonly prescribed pharmaceuticals as well as natural and synthetic hormones found in sewage. Analysis of targeted compounds was carried out by solid-phase extraction (SPE) and gas chromatography-mass spectrometry (GC-MS). Initial tests were undertaken to determine the background concentrations of the analytes during various stages of treatment. Subsequent tests, undertaken by spiking with standard solutions of the target compounds provided further information on the removal efficiencies of some selected treatment modules. The results of the study indicate that while ozonation, microfiltration and nanofiltration were partially effective, treatment by reverse osmosis was the most universally successful in the removal of the target residuals. While significantly more data is required for a full evaluation, this initial investigation suggests that reverse osmosis may be an effective means of removing a wider range of pharmaceutically active residuals and hormones from treated sewage.

The role of endocrine disrupters in water recycling: risk or mania?

The widespread occurrence of endocrine disrupting chemicals (EDCs), such as steroid hormones, in secondary wastewater effluents has become a major concern in the water recycling practice. This paper investigates the risk of steroid hormone breakthrough during nanofiltration membrane filtration in water recycling applications. The results indicate a dynamic equilibrium between adsorption and desorption of steroid hormone with regard to the membrane. This equilibrium can be pH dependent and there is a possibility for release of steroid hormones at high pH during membrane cleaning procedures or erratic pH variations. Increase in water recovery can severely increase the hormone breakthrough concentration. The results also indicate a possibility of accumulation of steroid hormones in the NF membrane, followed by subsequent release.

Removal of the natural hormone estrone from aqueous solutions using nanofiltration and reverse osmosis.

The ability of a variety of nanofiltration and reverse osmosis membranes to retain the natural hormone estrone are examined here as a function of solution conditions. While size exclusion dominates retention with the tighter membranes, both size exclusion and adsorptive effects appear to be instrumental in maintaining high retention on nanofiltration membranes that otherwise exhibit relatively low ion retentions. These adsorptive effects may be driven by hydrogen bonding between estrone and the membrane. Electrostatic attraction appears to aid retention with an apparent slight decrease in retention at high NaCl concentrations. Deprotonation of estrone leads to a significant decrease in retention, most likely as a result of the effect of strong electrostatic repulsive forces decreasing the proximity of the negatively charged estrone to the negatively charged membrane surface and thus lowering the potential for adsorptive retention. This deprotonation effect is absent for tight RO membranes. The results reported here indicate that while open nanofiltration membranes may be effective in retaining estrone under some conditions, the extent of retention may be very susceptible to maintenance of adsorptive capacity at the membrane surface and depend on solution chemistry.

Dsorption of estrone on nanofiltration and reverse osmosis membranes in water and wastewater treatment.

Adsorption of the trace contaminant estrone, a natural hormone and commonly abundant in surface waters and in treated as well as untreated wastewaters, to eight commercial nanofiltration and reverse osmosis membranes was investigated under well defined conditions. Experiments were conducted in stainless steel stirred cells by spiking trace levels (100 ng x L(-1)) of estrone into five different matrices, namely MilliQ water, a bicarbonate solution, synthetic natural waters containing natural organics, and secondary effluent. Results show that estrone is adsorbed to the membranes to varying degrees with extent of adsorption influenced by the feedwater composition with different mechanisms of association controlling adsorption to different membrane types. Increase in membrane resistance is typically observed to result in decrease in extent of estrone adsorption.

Adenovirus-mediated heme oxygenase-1 gene delivery inhibits injury-induced vascular neointima formation.

BACKGROUND: Recent studies have demonstrated that systemic pharmacological induction of heme oxygenase-1 (HO-1), the inducible isoform of the initial and rate-limiting enzyme for heme catabolism, attenuates neointima formation after experimental vascular injury. We have now investigated the ability of localized adenovirus-mediated HO-1 (Ad-HO-1) gene delivery to modify arterial remodeling after balloon angioplasty. METHODS AND RESULTS: Two weeks after balloon angioplasty in the rat carotid artery, elevated HO-1 protein was observed in the Ad-HO-1 arteries compared with those exposed to empty adenovirus (Ad-E) or to PBS. The arteries exposed to Ad-HO-1 exhibited significantly reduced neointimal area, medial wall area, neointimal area/medial wall area ratio, and neointimal thickness compared with arteries exposed to Ad-E. The Ad-E vessels showed subtle reductions in each morphometric parameter compared with PBS vessels. In a separate group of animals, concomitant treatment of Ad-HO-1 with the HO-1 inhibitor tin protoporphyrin completely restored each morphometric parameter to control levels. Arteries exposed to Ad-HO-1 demonstrated significantly increased TUNEL labeling of apoptotic nuclei and significantly decreased PCNA labeling of DNA synthesis in the medial wall 48 hours after injury. CONCLUSIONS: These results indicate that HO-1 represents an important in vivo vasoprotective mediator that is capable of attenuating the pathophysiological remodeling response to endovascular injury and suggest that HO-1 may be a novel target for the treatment of vascular disease.

Transforming growth factor-beta 1 stimulates vascular smooth muscle cell L-proline transport by inducing system A amino acid transporter 2 (SAT2) gene expression.

Transforming growth factor-beta1 (TGF-beta 1) is a multifunctional cytokine that contributes to arterial remodelling by stimulating vascular smooth muscle cell (SMC) growth and collagen synthesis at sites of vascular injury. Since l-proline is essential for the synthesis of collagen, we examined whether TGF-beta 1 regulates the transcellular transport of l-proline by vascular SMCs. l-Proline uptake by vascular SMCs was primarily sodium-dependent, pH-sensitive, blocked by neutral amino acids and alpha-(methylamino)isobutyric acid, and exhibited trans-inhibition. Treatment of SMCs with TGF-beta 1 stimulated l-proline transport in a concentration- and time-dependent manner. The TGF-beta 1-mediated l-proline uptake was inhibited by cycloheximide or actinomycin D. Kinetic studies indicated that TGF-beta 1-induced l-proline transport was mediated by an increase in transport capacity independent of any changes in the affinity for l-proline. TGF-beta 1 stimulated the expression of system A amino acid transporter 2 (SAT2) mRNA in a time-dependent fashion that paralleled the increase in l-proline transport. Reverse transcriptase PCR failed to detect the presence of SAT1 or amino acid transporter 3 (ATA3) in either untreated or TGF-beta 1-treated SMCs. These results demonstrate that l-proline transport by vascular SMCs is mediated predominantly by the SAT and that TGF-beta 1 stimulates SMC l-proline uptake by inducing the expression of the SAT2 gene. The ability of TGF-beta 1 to induce SAT2 expression may function to provide SMCs with the necessary levels of l-proline required for collagen synthesis and cell growth.

Antithrombotic therapy in patients with acute coronary syndromes.

The potential armamentarium of agents used in the treatment of acute coronary syndromes continues to expand, including such well-tested agents as aspirin, unfractionated heparin, and earlier-generation fibrinolytic agents, and newer agents such as low-molecular-weight heparins, direct thrombin inhibitors, thienopyridines, platelet glycoprotein IIb/IIIa receptor inhibitors, and bolus-administration fibrinolytic agents. Older and newer antithrombotic agents have undergone and continue to undergo intensive clinical investigation in patients with the clinical spectrum of acute coronary syndromes, which includes unstable angina, non-Q-wave (non-ST-segment elevation) myocardial infarction, and ST-segment elevation myocardial infarction. These studies, often conducted on an international scope and involving thousands of patients, provide data allowing practitioners to optimize the care of patients with acute coronary syndromes. In this article, studies of these established and newer agents in the treatment of patients with acute coronary syndromes are reviewed critically and summarized. Recommendations regarding use of antithrombotic agents in patients with acute coronary syndromes are then given.

Cost factors and chemical pretreatment effects in the membrane filtration of waters containing natural organic matter.

This paper compares the membrane processes available for water treatment. Membranes have the advantage of currently decreasing capital cost, a relatively small footprint compared to conventional treatment, generally a reduction in chemicals usage and comparably low maintenance requirements. Three membrane processes applicable to water treatment, micro- (MF), ultra- (UF), and nanofiltration (NF), are compared in terms of intrinsic rejection, variation of rejection due to membrane fouling and increase in rejection by ferric chloride pretreatment. Twelve different membranes are compared on the basis of their membrane pore size which was calculated from their molecular weight cut-off. A pore size of < 6 nm is required to achieve substantial (> 50%) organics removal. For a fouled membrane this pore size is about 11 nm. UV rejection is higher than DOC rejection. Coagulation pretreatment allows a higher rejection of organics by MF and UF and the cut-off criterion due to initial membrane pore size is no longer valid. A water quality parameter (WQP) is introduced which describes the product water quality achieved as a function of colloid, DOC and cation rejection. The relationship between log (pore size) and WQP is linear. Estimation of membrane costs as a function of WQP suggests that open UF is superior to MF (similar cost at higher WQP) and NF is superior to tight UF. Chemical pretreatment could compensate for the difference between MF and UF. However, when considering chemicals and energy costs, it appears that a process operated at a higher energy is cheaper at a guaranteed product quality (less dependent on organic type). This argument is further supported by environmental issues of chemicals usage, as energy may be provided from renewable sources.

Transforming growth factor-beta(1) stimulates L-arginine transport and metabolism in vascular smooth muscle cells: role in polyamine and collagen synthesis.

BACKGROUND: Transforming growth factor-beta(1) (TGF-beta(1)) contributes to arterial remodeling by stimulating vascular smooth muscle cell (VSMC) growth and collagen synthesis at sites of vascular injury. Because L-arginine is metabolized to growth-stimulatory polyamines and to the essential collagen precursor L-proline, we examined whether TGF-beta(1) regulates the transcellular transport and metabolism of L-arginine by VSMCs. METHODS AND RESULTS: TGF-beta(1) increased L-arginine uptake, and this was associated with a selective increase in cationic amino acid transporter-1 (CAT-1) mRNA. In addition, TGF-beta(1) stimulated L-arginine metabolism by inducing arginase I mRNA and arginase activity. TGF-beta(1) also stimulated L-ornithine catabolism by elevating ornithine decarboxylase (ODC) and ornithine aminotransferase (OAT) activity. TGF-beta(1) markedly increased the capacity of VSMCs to generate the polyamine putrescine and L-proline from extracellular L-arginine. The TGF-beta(1)-mediated increase in putrescine and L-proline production was reversed by methyl-L-arginine, a competitive inhibitor of cationic amino acid transport, or by hydroxy-L-arginine, an arginase inhibitor. Furthermore, the formation of putrescine was inhibited by the ODC inhibitor alpha-difluoromethylornithine, and L-proline generation was blocked by the OAT inhibitor L-canaline. L-Canaline also inhibited TGF-beta(1)-stimulated type I collagen synthesis. CONCLUSIONS: These results demonstrate that TGF-beta(1) stimulates polyamine and L-proline synthesis by inducing the genes that regulate the transport and metabolism of L-arginine. In addition, they show that TGF-beta(1)-stimulated collagen production is dependent on L-proline formation. The ability of TGF-beta(1) to upregulate L-arginine transport and direct its metabolism to polyamines and L-proline may contribute to arterial remodeling at sites of vascular damage.

Heme oxygenase-1 attenuates vascular remodeling following balloon injury in rat carotid arteries.

The heme oxygenase-1 (HO-1) system of heme catabolism has been proposed to exert protective actions upon the cardiovascular system. This investigation examined the influence of HO-1 induction on vascular remodeling following arterial injury. Rats were subjected to left carotid artery (LCA) balloon injury following pre-treatment with either vehicle, the HO-1 inducer hemin (50 mg/kg, SC), or concomitant treatment with hemin and the HO-1 inhibitor tin-protoporphyrin IX (SnPP-IX; 50 micromol/kg, IP). Animals were injected daily for 14 days post-injury, after which animals were sacrificed and tissues obtained. Western blot analyses revealed vascular HO-1 induction after 2 and 16 days of hemin treatment. Positive immunostaining for HO-1 was detected in the endothelial and adventitial layers following 48 h of hemin treatment and positive medial staining for HO-1 after 16 days of hemin treatment. The injured LCA of hemin-treated animals demonstrated significantly attenuated neointimal (NI) area (-57%), NI thickness (-58%), and NI area/medial wall area ratio (-40%) compared to the injured LCA of vehicle controls. The cross-sectional medial wall areas of both LCA and uninjured RCA were also significantly reduced in the hemin-treated animals. SnPP-IX treatment, however, completely restored the NI area, NI thickness, NI area/medial wall area ratio, and partially restored the medial wall area towards control levels. These results directly implicate HO-1 and the products of heme catabolism in attenuating the arterial response to injury and ensuing vascular wall remodeling.

Thrombocytosis and thrombocythemia.

Thrombocytosis is caused by three major pathophysiological mechanisms: (1) reactive or secondary thrombocytosis; (2) familial thrombocytosis; and (3) clonal thrombocytosis, including essential thrombocythemia and related myeloproliferative disorders. Recent work has begun to elucidate the abnormal megakaryocytopoiesis of essential thrombocythemia, which is associated with paradoxically elevated plasma levels of thrombopoietin. The clonal nature of all cases of essential thrombocythemia has been challenged. Thrombotic complications are the major causes of morbidity and mortality in this disease. Indications for platelet cytoreduction and antiplatelet therapy, as well as complications of treatment, are being clarified.