Hyperosmotic Mannitol Research Articles

Abstract P124: Piezo1 Mediates Vasodilation Induced By Acute Hyperglycemia In Mouse Renal Arteries And Microvessels

Background: Acute hyperglycemia (HG) is a risk factor for developing acute kidney injury and poor renal outcome in critically ill patients. The role of renal vasculature in this context is not clear. We hypothesize that HG-associated hyperosmolarity facilitates vasodilation through Piezo1-mediated eNOS activation. Methods: Vasoreactivity of isolated mouse mesenteric (MA) and renal interlobar (ILA) arteries were analyzed using wire myography and that of renal afferent (AA) and efferent (EA) arterioles, and vasa recta (VR) using microvascular perfusion. Immunofluorescence and western blot were used for molecular analyses of isolated mouse blood vessels as well HUVECs. Results: Pre-treatment with HG (44 mmol L -1 glucose; 4 h) increased acetylcholine (ACh)-induced relaxation in ILA and MA, which was prevented by eNOS inhibition using L-NAME. Hyperosmotic mannitol solution had a similar effect. HG induced an immediate, L-NAME-inhibitable dilation in AA, EA, and VR, whereby stronger dilation in AA compared to EA. HG also increased glomerular filtration rate in mice. In HUVECs, HG and the Piezo1 activator Yoda1 increased levels of Piezo1 protein, phosphorylated CaMKII (p-CaMKII), Akt, and p-eNOS. The HG-effect could be prevented by inhibiting Piezo1 using GsMTx4 and CaMKII using KN93. Furthermore, in arteries and microvessels, inhibition of Piezo1 using GsMTx4 prevented the HG-effect, while Yoda1 caused relaxation and dilation, respectively. Conclusion: Results reveal that Piezo1 mediates renal vasodilation induced by hyperosmolarity in acute HG. This mechanism may contribute to the pathogenesis of renal damage by acute HG.

Piezo1 Mediates Vasodilation Induced by Acute Hyperglycemia in Mouse Renal Arteries and Microvessels.

Acute hyperglycemia is a risk factor for developing acute kidney injury and poor renal outcome in critically ill patients, whereby the role of renal vasculature remains unclear. We hypothesize that hyperglycemia-associated hyperosmolarity facilitates vasodilation through Piezo1-mediated eNOS (endothelial NO synthase) activation. Vasoreactivity was analyzed using wire myography in isolated mouse mesenteric arteries and renal interlobar, and using microvascular perfusion in renal afferent arterioles and efferent arterioles, and vasa recta. Immunofluorescence and Western blot were used for molecular analyses of isolated mouse blood vessels and human umbilical vein endothelial cells. Pretreatment with hyperglycemia (44 mmol/L glucose; 4 hours) increased acetylcholine-induced relaxation in interlobar arteries and mesenteric arteries, which was prevented by eNOS inhibition using Nω-nitro-L-arginine methylester hydrochloride. Hyperosmotic mannitol solution had a similar effect. Hyperglycemia induced an immediate, Nω-nitro-L-arginine methylester hydrochloride-inhibitable dilation in afferent arterioles, efferent arterioles, and vasa recta, whereby stronger dilation in afferent arterioles compared to efferent arterioles. Hyperglycemia also increased glomerular filtration rate in mice. In human umbilical vein endothelial cells, hyperglycemia, and the Piezo1 activator Yoda-1 increased levels of Piezo1 protein, p-CaMKII (phosphorylated Ca2+/Calmodulin-dependent protein kinase type II), Akt, and p-eNOS (phosphorylated eNOS). The hyperglycemia effect could be prevented by inhibiting Piezo1 using GsMTx4 (Grammostola spatulata mechanotoxin 4) and CaMKII using KN93. Furthermore, in arteries and microvessels, inhibition of Piezo1 using GsMTx4 prevented the hyperglycemia -effect, while Yoda-1 caused relaxation and dilation, respectively. Results reveal that Piezo1 mediates renal vasodilation induced by hyperosmolarity in acute hyperglycemia. This mechanism may contribute to the pathogenesis of renal damage by acute hyperglycemia.

Hyperosmotic stress induces epithelial-mesenchymal transition through rearrangements of focal adhesions in tubular epithelial cells.

Epithelial-mesenchymal transition (EMT) of tubular epithelial cells is a hallmark of renal tubulointerstitial fibrosis and is associated with chronic renal injury as well as acute renal injury. As one of the incidences and risk factors for acute renal injury, increasing the osmolality in the proximal tubular fluid by administration of intravenous mannitol has been reported, but the detailed mechanisms remain unclear. Hyperosmotic conditions caused by mannitol in the tubular tissue may generate not only osmotic but also mechanical stresses, which are known to be able to induce EMT in epithelial cells, thereby contributing to renal injury. Herein, we investigate the effect of hyperosmolarity on EMT in tubular epithelial cells. Normal rat kidney (NRK)-52E cells were exposed to mannitol-induced hyperosmotic stress. Consequently, the hyperosmotic stress led to a reduced expression of the epithelial marker E-cadherin and an enhanced expression of the mesenchymal marker, α-smooth muscle actin (α-SMA), which indicates an initiation of EMT in NKR-52E cells. The hyperosmotic condition also induced time-dependent disassembly and rearrangements of focal adhesions (FAs) concomitant with changes in actin cytoskeleton. Moreover, prevention of FAs rearrangements by cotreatment with Y-27632, a Rho-associated protein kinase inhibitor, could abolish the effects of hyperosmotic mannitol treatment, thus attenuating the expression of α-SMA to the level in nontreated cells. These results suggest that hyperosmotic stress may induce EMT through FAs rearrangement in proximal tubular epithelial cells.

Hyperosmolar blood-brain barrier opening using intra-arterial injection of hyperosmotic mannitol in mice under real-time MRI guidance.

The blood-brain barrier (BBB) is the main obstacle to the effective delivery of therapeutic agents to the brain, compromising treatment efficacy for a variety of neurological disorders. Intra-arterial (IA) injection of hyperosmotic mannitol has been used to permeabilize the BBB and improve parenchymal entry of therapeutic agents following IA delivery in preclinical and clinical studies. However, the reproducibility of IA BBB manipulation is low and therapeutic outcomes are variable. We demonstrated that this variability could be highly reduced or eliminated when the procedure of osmotic BBB opening is performed under the guidance of interventional MRI. Studies have reported the utility and applicability of this technique in several species. Here we describe a protocol to open the BBB by IA injection of hyperosmotic mannitol under the guidance of MRI in mice. The procedures (from preoperative preparation to postoperative care) can be completed within ~1.5 h, and the skill level required is on par with the induction of middle cerebral artery occlusion in small animals. This MRI-guided BBB opening technique in mice can be utilized to study the biology of the BBB and improve the delivery of various therapeutic agents to the brain.

Malignant astrocyte swelling and impaired glutamate clearance drive the expansion of injurious spreading depolarization foci

Spreading depolarizations (SDs) indicate injury progression and predict worse clinical outcome in acute brain injury. We demonstrate in rodents that acute brain swelling upon cerebral ischemia impairs astroglial glutamate clearance and increases the tissue area invaded by SD. The cytotoxic extracellular glutamate accumulation (>15 µM) predisposes an extensive bulk of tissue (4–5 mm2) for a yet undescribed simultaneous depolarization (SiD). We confirm in rat brain slices exposed to osmotic stress that SiD is the pathological expansion of prior punctual SD foci (0.5–1 mm2), is associated with astrocyte swelling, and triggers oncotic neuron death. The blockade of astrocytic aquaporin-4 channels and Na+/K+/Cl− co-transporters, or volume-regulated anion channels mitigated slice edema, extracellular glutamate accumulation (<10 µM) and SiD occurrence. Reversal of slice swelling by hyperosmotic mannitol counteracted glutamate accumulation and prevented SiD. In contrast, inhibition of glial metabolism or inhibition of astrocyte glutamate transporters reproduced the SiD phenotype. Finally, we show in the rodent water intoxication model of cytotoxic edema that astrocyte swelling and altered astrocyte calcium waves are central in the evolution of SiD. We discuss our results in the light of evidence for SiD in the human cortex. Our results emphasize the need of preventive osmotherapy in acute brain injury.

Salinomycin-Loaded Iron Oxide Nanoparticles for Glioblastoma Therapy.

Salinomycin is an antibiotic introduced recently as a new and effective anticancer drug. In this study, magnetic iron oxide nanoparticles (IONPs) were utilized as a drug carrier for salinomycin for potential use in glioblastoma (GBM) chemotherapy. The biocompatible polyethylenimine (PEI)-polyethylene glycol (PEG)-IONPs (PEI-PEG-IONPs) exhibited an efficient uptake in both mouse brain-derived microvessel endothelial (bEnd.3) and human U251 GBM cell lines. The salinomycin (Sali)-loaded PEI-PEG-IONPs (Sali-PEI-PEG-IONPs) released salinomycin over 4 days, with an initial release of 44% ± 3% that increased to 66% ± 5% in acidic pH. The Sali-IONPs inhibited U251 cell proliferation and decreased their viability (by approximately 70% within 48 h), and the nanoparticles were found to be effective in reactive oxygen species-mediated GBM cell death. Gene studies revealed significant activation of caspases in U251 cells upon treatment with Sali-IONPs. Furthermore, the upregulation of tumor suppressors (i.e., p53, Rbl2, Gas5) was observed, while TopII, Ku70, CyclinD1, and Wnt1 were concomitantly downregulated. When examined in an in vitro blood–brain barrier (BBB)-GBM co-culture model, Sali-IONPs had limited penetration (1.0% ± 0.08%) through the bEnd.3 monolayer and resulted in 60% viability of U251 cells. However, hyperosmotic disruption coupled with an applied external magnetic field significantly enhanced the permeability of Sali-IONPs across bEnd.3 monolayers (3.2% ± 0.1%) and reduced the viability of U251 cells to 38%. These findings suggest that Sali-IONPs combined with penetration enhancers, such as hyperosmotic mannitol and external magnetic fields, can potentially provide effective and site-specific magnetic targeting for GBM chemotherapy.

High-dose phenylephrine increases meningeal blood flow through TRPV1 receptor activation and release of calcitonin gene-related peptide.

The α1 -adrenoceptor agonist, phenylephrine, is used at high concentrations as a mydriatic agent and for the treatment of nasal congestion. Among its adverse side-effects transient burning sensations are reported indicating activation of the trigeminal nociceptive system. Neuropeptide release, calcium imaging and meningeal blood flow recordings were applied in rodent models of meningeal nociception to clarify possible receptor mechanisms underlying these pain phenomena. Phenylephrine above 10mM dose-dependently released calcitonin gene-related peptide (CGRP) from the dura mater and isolated trigeminal ganglia, whereas hyperosmotic mannitol at 90mM was ineffective. The phenylephrine-evoked release was blocked by the transient receptor potential vanilloid 1 (TRPV1) antagonist BCTC and did not occur in trigeminal ganglia of TRPV1-deficient mice. Phenylephrine at 30mM caused calcium transients in cultured trigeminal ganglion neurons responding to the TRPV1 agonist capsaicin and in HEK293T cells expressing human TRPV1. Local application of phenylephrine at micromolar concentrations to the exposed rat dura mater reduced meningeal blood flow, whereas concentrations above 10mM caused increased meningeal blood flow. The flow increase was abolished by pre-application of the CGRP receptor antagonist CGRP8-37 or the TRPV1 antagonist BCTC. Phenylephrine at high millimolar concentrations activates TRPV1 receptor channels of perivascular afferents and, upon calcium inflow, releases CGRP, which increases meningeal blood flow. Activation of TRPV1 receptors may underlie trigeminal nociception leading to cranial pain such as local burning sensations or headaches caused by administration of high doses of phenylephrine. Phenylephrine is used at high concentrations as a mydriaticum and for treating nasal congestion. As adverse side-effects burning sensations and headaches have been described. Phenylephrine at high concentrations causes calcium transients in trigeminal afferents, CGRP release and increased meningeal blood flow upon activation of TRPV1 receptor channels, which is likely underlying the reported pain phenomena.

Effect of Osmolality on the Pharmacokinetic Interaction between Apple Juice and Atenolol in Rats.

A recent clinical study reported that the ingestion of apple juice (AJ) markedly reduced the plasma concentration of atenolol; however, our in vitro study showed that atenolol may not be a substrate of organic anion transporting polypeptide 2B1 (OATP2B1), so this AJ-atenolol interaction cannot be explained by inhibition of OATP2B1. On the other hand, we more recently showed that the solution osmolality influences gastrointestinal (GI) water volume, and this may indirectly affect intestinal drug absorption. In this study, we examined whether the osmolality dependence of water dynamics can account for AJ-atenolol interactions by evaluating the GI water volume and the atenolol aborption in the presence of AJ in rats. Water absorption was highest in purified water, followed by saline and isosmotic mannitol solution, and the lowest in AJ, confirming that water absorption is indeed osmolality-dependent. Interestingly, AJ showed apparent water secretion into the intestinal lumen. The intestinal concentration of FD-4, a nonpermeable compound, after administration in AJ was lower than the initial concentration, whereas that in purified water was greater than the initial concentration. Further, the fraction of atenolol absorbed in intestine was significantly lower in AJ or hyperosmotic mannitol solution (adjusted to the osmolality of AJ) than after administration in purified water. Comparable results were observed in an in vivo pharmacokinetic study in rats. Our results indicate that orally administered AJ has a capacity to modulate luminal water volume depending on the osmolality, and this effect may result in significant AJ-atenolol interactions.

Real-Time MRI Guidance for Reproducible Hyperosmolar Opening of the Blood-Brain Barrier in Mice.

The blood-brain barrier (BBB) prevents effective delivery of most therapeutic agents to the brain. Intra-arterial (IA) infusion of hyperosmotic mannitol has been widely used to open the BBB and improve parenchymal targeting, but the extent of BBB disruption has varied widely with therapeutic outcomes often being unpredictable. In this work, we show that real-time MRI can enable fine-tuning of the infusion rate to adjust and predict effective and local brain perfusion in mice, and thereby can be allowed for achieving the targeted and localized BBB opening (BBBO). Both the reproducibility and safety are validated by MRI and histology. The reliable and reproducible BBBO we developed in mice will allow cost-effective studies on the biology of the BBB and drug delivery to the brain. In addition, the IA route for BBBO also permits subsequent IA delivery of a specific drug during the same procedure and obtains high targeting efficiency of the therapeutic agent in the targeted tissue, which has great potential for future clinical translation in neuro-oncology, regenerative medicine and other neurological applications.

Strategies that Target Tight Junctions for Enhanced Drug Delivery.

Ions and molecules move across epithelial barriers by two pathways, the transcellular and the paracellular. The former is taken by lipophilic compounds, or by ions and molecules that move across the plasma membrane through pumps, carriers or exchangers. The second route is regulated by the tight junction (TJ) that through paracellular channels, allows the transport of ions across epithelial barriers. Since, a wide variety of bioactive molecules like peptides, proteins and oligonucleotides cannot use the transcellular route, due to their hydrophilic nature, interest has arisen in devising procedures to open the TJ in a reversible manner for paracellular drug delivery. Here, we describe how different strategies have been devised to enhance the paracellular intestinal absorption of drugs; to open the blood-brain barrier (BBB) to allow the penetration of drugs for the treatment of disorders and tumors of the central nervous system; or to deliver antigens into the subjacent mucosa associated lymphoid tissues, for the development of mucosal vaccines. The strategies described, include the use of peptides, antibodies and miRNAs that target proteins of the apical junctional complex, as well as toxins derived from microorganisms that open the TJ by inducing the contraction of the cortical actomyosin ring. Also, we describe how paracellular absorption, is enhanced by drugs that extract cholesterol from the plasma membrane, surfactants, fatty acids, oligosaccharides, cationic polymers, nitric oxide donors and calcium chelators. Likewise, we explain how the BBB has been opened by employing tumor necrosis factor-α, bradykinin, short chain alkylglycerols, hyperosmotic mannitol and focused ultrasound.

Pharmaceutical Targeting of the Brain.

Besides being indispensable for the protection and nutrition of the central nervous system (CNS), blood-brain barrier (BBB)-forming cerebral endothelial cells (CECs) have a major role in hampering drugs to reach therapeutically relevant concentrations in the brain. In this respect, the most important defense systems of CECs are tight junctions (TJs) sealing the paracellular way of transport, efflux pumps (ABC transporters) and metabolic enzymes. Here we review current strategies aiming at overcoming the BBB with the purpose of effectively delivering drugs to the CNS. Besides chemical modification of drug candidates to improve CNS availability, the main strategies include: bypassing the BBB (intracranial or nasal routes), reversible opening of TJs (using hyperosmotic mannitol, ultrasounds, peptides and other physical methods or chemical agents), vector-mediated drug delivery systems (nanocarriers, exploitation of receptor- and carrier-mediated transport) and inhibition of efflux transporters. We discuss the main advantages, disadvantages and clinical relevance of each strategy. Special emphasis will be given to the description of the chemical characteristics of nanoparticles (lipidic, polymeric, inorganic, etc.) and the main strategies of targeting them to the CNS.

Targeted Modification of Mitochondrial ROS Production Converts High Glucose-Induced Cytotoxicity to Cytoprotection: Effects on Anesthetic Preconditioning.

Contradictory reports on the effects of diabetes and hyperglycemia on myocardial infarction range from cytotoxicity to cytoprotection. The study was designed to investigate acute effects of high glucose-driven changes in mitochondrial metabolism and osmolarity on adaptive mechanisms and resistance to oxidative stress of isolated rat cardiomyocytes. We examined the effects of high glucose on several parameters of mitochondrial bioenergetics, including changes in oxygen consumption, mitochondrial membrane potential, and NAD(P)H fluorometry. Effects of high glucose on the endogenous cytoprotective mechanisms elicited by anesthetic preconditioning (APC) and the mediators of cell injury were also tested. These experiments included real-time measurements of reactive oxygen species (ROS) production and mitochondrial permeability transition pore (mPTP) opening in single cells by laser scanning fluorescence confocal microscopy, and cell survival assay. High glucose rapidly enhanced mitochondrial energy metabolism, observed by increase in NAD(P)H fluorescence intensity, oxygen consumption, and mitochondrial membrane potential. This substantially elevated production of ROS, accelerated opening of the mPTP, and decreased survival of cells exposed to oxidative stress. Abrogation of high glucose-induced mitochondrial hyperpolarization with 2,4 dinitrophenol (DNP) significantly, but not completely, attenuated ROS production to a level similar to hyperosmotic mannitol control. DNP treatment reversed high glucose-induced cytotoxicity to cytoprotection. Hyperosmotic mannitol treatment also induced cytoprotection. High glucose abrogated APC-induced mitochondrial depolarization, delay in mPTP opening and cytoprotection. In conclusion, high glucose-induced mitochondrial hyperpolarization abolishes APC and augments cell injury. Attenuation of high glucose-induced ROS production by eliminating mitochondrial hyperpolarization protects cardiomyocytes. J. Cell. Physiol. 232: 216-224, 2017. © 2016 Wiley Periodicals, Inc.

Modulation of Hyperosmotic and Immune-Induced Disruption of the Blood-Brain Barrier by the Nitric Oxide System

Objectives: The role of nitric oxide (NO) in modulating the blood-brain barrier (BBB) is not entirely clear. We examined the effect of different NO synthase (NOS) inhibitors and NO donors on the permeability of the BBB in animals with normally functioning brain blood vessels, following disruption by hyperosmotic mannitol and during immune inflammation. Methods: We administered L-NAME, aminoguanidine, S-methyl-thiocitrulline (SMT) and 7-indazole (NOS inhibitors) and NOR-4 (an NO donor) into the cerebral ventricle of rats. Disruption of the BBB was induced by intracarotid injection of mannitol (25%). Experimental autoimmune encephalomyelitis (EAE) was induced by brain homogenate. The extent of disruption was evaluated by Evans blue (2%) dye extravasation. Results: L-NAME (a nonspecific NOS inhibitor) and SMT (a neuronal and endothelial NOS inhibitor) increased mannitol-induced disruption of BBB. This effect was inhibited by NO donors. In animals with a normally functioning BBB, none of these inhibitors or NO donors caused a change in the permeability. 7-indazole (a specific neuronal NOS inhibitor) and aminoguanidine (an inducible NOS inhibitor) had no facilitatory effect on BBB permeability, either alone or in combination with hyperosmotic mannitol. Administration of L-NAME and SMT to rats with EAE significantly aggravated the clinical outcome. In contrast, the administration of NOR-4 diminished clinical signs of EAE. Conclusion: The NOS system does not play a role in BBB permeability in naïve animals. Only endothelial NOS takes part in the facilitation of BBB compromised by mannitol and EAE. Extrinsic NO decreases this facilitatory effect.

Collagen-based brain microvasculature model in vitro using three-dimensional printed template.

We present an engineered three-dimensional (3D) in vitro brain microvasculature system embedded within the bulk of a collagen matrix. To create a hydrogel template for the functional brain microvascular structure, we fabricated an array of microchannels made of collagen I using microneedles and a 3D printed frame. By culturing mouse brain endothelial cells (bEnd.3) on the luminal surface of cylindrical collagen microchannels, we reconstructed an array of brain microvasculature in vitro with circular cross-sections. We characterized the barrier function of our brain microvasculature by measuring transendothelial permeability of 40 kDa fluorescein isothiocyanate-dextran (Stoke's radius of ∼4.5 nm), based on an analytical model. The transendothelial permeability decreased significantly over 3 weeks of culture. We also present the disruption of the barrier function with a hyperosmotic mannitol as well as a subsequent recovery over 4 days. Our brain microvasculature model in vitro, consisting of system-in-hydrogel combined with the widely emerging 3D printing technique, can serve as a useful tool not only for fundamental studies associated with blood-brain barrier in physiological and pathological settings but also for pharmaceutical applications.

Delivery of chemotherapeutics across the blood-brain barrier: challenges and advances.

The blood-brain barrier (BBB) limits drug delivery to brain tumors. We utilize intraarterial infusion of hyperosmotic mannitol to reversibly open the BBB by shrinking endothelial cells and opening tight junctions between the cells. This approach transiently increases the delivery of chemotherapy, antibodies, and nanoparticles to brain. Our preclinical studies have optimized the BBB disruption (BBBD) technique and clinical studies have shown its safety and efficacy. The delivery of methotrexate-based chemotherapy in conjunction with BBBD provides excellent outcomes in primary central nervous system lymphoma (PCNSL) including stable or improved cognitive function in survivors a median of 12 years (range 2-26 years) after diagnosis. The addition of rituximab to chemotherapy with BBBD for PCNSL can be safely accomplished with excellent overall survival. Our translational studies of thiol agents to protect against platinum-induced toxicities led to the development of a two-compartment model in brain tumor patients. We showed that delayed high-dose sodium thiosulfate protects against carboplatin-induced hearing loss, providing the framework for large cooperative group trials of hearing chemoprotection. Neuroimaging studies have identified that ferumoxytol, an iron oxide nanoparticle blood pool agent, appears to be a superior contrast agent to accurately assess therapy-induced changes in brain tumor vasculature, in brain tumor response to therapy, and in differentiating central nervous system lesions with inflammatory components. This chapter reviews the breakthroughs, challenges, and future directions for BBBD.

Oxidative stress status in umbilical cord blood from neonates born to mothers with atopic asthma

Objective: Our objective was to assess the oxidative stress status and analyse the relationship between an oxidant/antioxidant imbalance and the mediator release properties of cord blood basophils from neonates born to mothers with atopic asthma.Methods: Cord blood was collected from the neonates of 16 asthmatic mothers and 18 healthy mothers Basophils were purified and stimulated by Dermatophagoides farinae (Df), hyperosmotic mannitol or peptidoglycan (PGN). Immunoblotting detected nuclear factor κB (NFκB) as a measure of functional receptor response. The linear correlations between IL-4 levels in the supernatants and 3-nitrotyrosine (3-NT), glutathione peroxidase (GSH-Px) in the serum were evaluated.Results: Compared with the healthy group, the levels of 3-NT in maternal blood and cord blood were significantly higher in allergic asthma group, whereas the GSH-Px activity were lower. After stimulation, cord blood basophils from the neonates born to atopic mothers produced more IL-4 involving NF-κB pathways. There was a significant relationship between the IL-4 levels produced by basophils and 3-NT (or GSH-Px) in cord blood from allergic asthma group.Conclusion: In asthma, mediator release properties of human basophils induced by environmental allergens and irritants are associated with oxidative stress, which may be one of the pathogenesis of allergic diseases.

The Effect of Stimuli on Basophil-Mediated Atopic Responses During Asthmatic Lying-In Women and in Newborns

Morbidity from allergic diseases is increasing. Basophils play a critical role in systemic anaphylaxis and chronic allergic inflammation. The prenatal environment must be regarded as a possible early risk factor for allergic diseases in children. Our objective was to determine if basophils harvested from neonates genetically predisposed to atopic disease had different levels of CD63 expression and IL-4 release properties in response to various stimuli (peptidoglycan, Dermatophagoides farinae, hyperosmotic mannitol). Blood samples were collected from 16 asthmatic and 18 healthy women and their newborns. Peripheral blood basophil histamine was measured using the human basophil degranulation test (HBDT), whereas activation was assessed by flow cytometric measurement of CD63 expression on the cord blood basophil surface. IL-4 levels were quantified by ELISA following allergen stimulation. The basophil degranulation index (DI) in granulocytes harvested from the peripheral blood of asthmatic women was assessed following stimulation with peptidoglycan (PGN), Dermatophagoides farinae (Df ) extract, or hyperosmotic mannitol. The DI was significantly higher in atopic women than in healthy controls. Upregulation of CD63 on the cord blood basophil surface was also detected in response to these stimuli. Basophils purified from the cord blood of neonates born to atopic mothers produced more IL-4 compared to basophils purified from the controls. These data suggested that various stimuli play a role in augmenting allergic reactions via modulation of activated basophil cytokine secretion. It may require new methods to stabilize the basophils in allergic diseases.

Effects of Hyperosmotic Sodium Chloride Perfusion on Ischemia/Reperfusion Injury in Isolated Hearts of Normal and Stroke-Prone Spontaneously Hypertensive Rats

Background: Hyperosmotic solutions have been used successfully in different shock resuscitations with cardioprotection. This study was to examine the effects of hyperosmotic sodium chloride on isolated heart function and heart responses to ischemia/reperfusion in normotensive and hypertensive rats. The roles of hyperosmolarity-induced antioxidants including hyperosmolarity-relevant heat shock proteins as well as vasodilating endothelial nitric oxide synthase (eNOS) and vasoactive catecholamines were investigated.Methods: Hearts of normal rats and stroke-prone spontaneously hypertensive rats were isolated and perfused for 30 min with control Krebs-Henseleit buffer (osmolarity 300 mOsm/L) or hyperosmotic buffer of different sodium chloride concentrations (320, 350 and 400 mOsm/L) before subjected to 40-min global ischemia followed by 10-min hyperosmotic reperfusion and 30-min normal buffer reperfusion. Heart function, creatine phosphokinase leakage and myocardial antioxidants were examined. Myocardial antioxidants after hyperosmotic perfusion with different osmolytes were assayed with Western blotting.Results: Pre-ischemic hyperosmotic sodium chloride perfusion enhanced heart contractility and diastole function and reduced coronary vascular resistance in both normal and hypertensive hearts. Post-ischemic recoveries of heart function were improved in hyperosmotic perfused hearts, associated with lower creatine phosphokinase leakage, higher coronary flow, reduced coronary resistance and lower norepinephrine overflow. At the end of reperfusion, the myocardial activities of total superoxide dismutase and catalase, glutathione content as well as osmosis-relevant heat shock protein 32 and 90 were increased in hyperosmotic hearts. In addition to sodium chloride, in vitro hyperosmotic mannitol, glucose and raffinose also increased protein expressions of antioxidants including superoxide dismutase, catalase, heat shock protein 32 and 90 and vasodilating eNOS.Conclusion: Hyperosmotic perfusion enhanced heart function and preconditioned normal and hypertensive hearts against ischemia/reperfusion injury. The hyperosmolarity-induced up-regulations in myocardial antioxidants including heat shock proteins and eNOS may play an important role in the hyperosmolarity-induced cardioprotection.

Enhancement of electric field-mediated gene delivery through pretreatment of tumors with a hyperosmotic mannitol solution

Pulsed electric fields can enhance interstitial transport of plasmid DNA (pDNA) in solid tumors. However, the extent of enhancement is still limited. To this end, effects of cellular resistance to electric field-mediated gene delivery were investigated. The investigation used two tumor cell lines (4T1 and B16.F10) either in suspensions or implanted in two in vivo models (dorsal skin-fold chamber (DSC) and hind leg). The volume fraction of cells was altered by pretreatment with a hyperosmotic mannitol solution (1 M). It was observed that the pretreatment reduced the volumes of 4T1 and B16.F10 cells, suspended in an agarose gel, by 50% and 46%, respectively, over a 20-min period but did not cause significant changes ex vivo in volumes of hind leg tumor tissues grown from the same cells in mice. The mannitol pretreatment in vivo improved electric field-mediated gene delivery in the hind leg tumor models, in terms of reporter gene expression, but resulted in minimal enhancement in pDNA electrophoresis over a few micron distance in the DSC tumor models. These data demonstrated that hyperosmotic mannitol solution could effectively improve electric field-mediated gene delivery around individual cells in vivo through increasing the extracellular space.

Mitochondrial proline oxidation is affected by hyperosmotic stress in durum wheat seedlings

The important role of plant mitochondria in the adaptation to environmental stresses at subcellular level has recently emerged. In particular, an important mitochondrial mechanism involved in the resistance to environmental stresses is the inhibition of proline oxidation. In order to study this physiological mechanism, we used both washed and purified durum wheat (Triticum durum) mitochondria (DWM) isolated from early seedlings germinated in two different NaCl solutions leading to either moderate or severe damage to growth. To assess the contribution of the osmotic component of stress, a parallel investigation was performed using hyperosmotic mannitol solutions. Comparison of the oxygen uptake rate in the course of proline oxidation, with that of the malate plus glutamate substrate pair and that of succinate showed that an early inhibition of proline oxidation occurs under stress. The drop of the proline-dependent oxygen uptake rate was as a result of a heavy inhibition of proline dehydrogenase (ProDH); on the other hand, malate plus glutamate-dependent and succinate-dependent oxidations were less inhibited, being the maintenance of oxygen uptake rate not dependent on alternative oxidase (AOX) pathway; in fact, DWM-AOX activity did not show any increase under our experimental stress conditions. The selective inhibition of proline oxidation should be considered a mitochondrial adaptation to stress rather than damage to mitochondrial oxidative properties. This result was achieved by means of a novel approach based on the comparison between oxygen uptake rates of washed and purified organelles.