Renal radionuclide scintigraphy in the evaluation of radiopaque substances on renal function

To evaluate the nephrotoxic effect of radiopaque substances (ROS) by renal radionuclide scintigraphy, 47 patients were examined before and after coronary ventriculography. Iohexol, iobitridole, and ioxythalamate were used as ROS in 15, 18, and 14 patients, respectively. The parameters of renal filtration and excretory function were calculated during study. Ioxythalamate was shown to have a less pronounced nephrotoxic effect.     

Manometric changes during retrograde biliary infusion in mice

The manometric, ultrastructural, radiographic, and physiological consequences of retrograde biliary infusion were determined in normostatic and cholestatic mice. Intraluminal biliary pressure changed as a function of infusion volume, rate, and viscosity. Higher rates of constant infusion resulted in higher peak intraluminal biliary pressures. The pattern of pressure changes observed was consistent with biliary ductular and/or canalicular filling followed by leakage at a threshold pressure. Retrograde infusion with significant elevations in pressure led to paracellular leakage of lanthanum chloride, radiopaque dye, and [(14)C]sucrose with rapid systemic redistribution via sinusoidal and subsequent hepatic venous drainage. Chronic extrahepatic bile duct obstruction resulted in significantly smaller peak intrabiliary pressures and lower levels of paracellular leakage. These findings indicate that under both normostatic and cholestatic conditions elevated intrabiliary volumes/pressures result in an acute pressure-dependent physical opening of tight junctions, permitting the movement of infusate from the intrabiliary space into the subepithelial tissue compartment. Control of intraluminal pressure may potentially permit the selective delivery of macromolecules >18-20 A in diameter to specific histological compartments.     

Radiopaque magnetic medium oleoferrotrast, its x-ray specific properties and toxicity]

The paper reviews results of physicochemical and x-ray specific properties of a new magnetic radiopaque medium oleoferrotrast. The latter proved nontoxic, has radiopaque and magnetic adequacy for special x-ray examinations.     

Skeletal muscle reactive oxygen species: A target of good cop/bad cop for exercise and disease

Abstract

Metabolic stresses associated with disease, ageing, and exercise increase the levels of reactive oxygen species (ROS) in skeletal muscle. These ROS have been linked mechanistically to adaptations in skeletal muscle that can be favourable (i.e. in response to exercise) or detrimental (i.e. in response to disease). The magnitude, duration (acute versus chronic), and cellular origin of the ROS are important underlying factors in determining the metabolic perturbations associated with the ROS produced in skeletal muscle. In particular, insulin resistance has been linked to excess ROS production in skeletal muscle mitochondria. A chronic excess of mitochondrial ROS can impair normal insulin signalling pathways and glucose disposal in skeletal muscle. In contrast, ROS produced in skeletal muscle in response to exercise has been linked to beneficial metabolic adaptations including mitochondrial biogenesis and muscle hypertrophy. Moreover, unlike insulin resistance, exercise-induced ROS appears to be primarily of non-mitochondrial origin. The present review summarizes the diverse ROS-targeted metabolic outcomes associated with insulin resistance versus exercise in skeletal muscle, thus, presenting two contrasting perspectives of pathologically harmful versus physiologically beneficial ROS. Here, we discuss the key sites of ROS production during exercise and the effect of ROS in skeletal muscle of people with type 2 diabetes.     

Alteration of retinal rod outer segment membrane fluidity in a rat model of Smith-Lemli-Opitz syndrome

Smith-Lemli-Opitz syndrome (SLOS) is caused by an inherited defect in the last step in cholesterol (Chol) biosynthesis, leading to abnormal accumulation of 7-dehydrocholesterol and decreased Chol levels. Progressive retinal degeneration occurs in an animal model of SLOS, induced by treating rats with AY9944, a selective inhibitor of the enzyme affected in SLOS. Here we evaluated alterations in the biochemical and physical properties of retinal rod outer segment (ROS) membranes in this animal model. At 1 month of AY9944 treatment, there were modest alterations in fatty acid composition, but no significant differences in cis-parinaric acid (cPA) spectroscopic parameters in ROS membranes from treated versus control rats. However, at 3 months, ROS docosahexaenoic acid (DHA) content was dramatically reduced, and cPA fluorescence anisotropy values were decreased, relative to controls. Also, 1,6-diphenyl-1,3,5-hexatriene exhibited decreased rotational motion and increased orientational order in ROS membranes from 3 month-old AY9944-treated rats, relative to controls. No significant changes in protein:lipid ratios were observed; however, rhodopsin regenerability was compromised by 3 months of treatment. These findings are consistent with reduced ROS membrane fluidity in the SLOS rat model, relative to controls, primarily due to the dramatic reduction in membrane DHA levels, rather than altered sterol composition.     

Aggregation and release reaction of washed platelets stimulated by lanthanum.

Ionized lanthanum caused clumping of washed platelets. This clumping response could be reversed by chelating agents but was not impaired by known inhibitors of platelets aggregation. Aggregation by lanthanum was not restricted to the unique clumping properties of platelets but occurred in fixed platelets and red cells and was most likely based on an electrostatic interaction.Lanthanum was able to stimulate as well as to inhibit serotonin release from platelets.At a concentration of 1 mM, lanthanum evoked a release of serotonin from washed platelets at 37°C. This release reaction was inhibited at 18°C or by prior treatment of platelets with neuraminidase or NEM.At a high concentration (10 mM), lanthanum did not stimulate the platelet release reaction but inhibited that induced by all stimuli investigated, presumably due to a fixation of membrane molecules.The release reaction promoted by thrombin or A 23187, but not that by collagen, was inhibited by a low concentration of lanthanum (0.1 mM). This inhibition is based on an interaction of lanthanum with the stimuli rather than with the platelet surface.     

Effects of low-molecular-weight organic acids on uptake of lanthanum by wheat roots

Effects of low-molecular-weight organic acids (LMWOAs) on the uptake of lanthanum by wheat (Triticum aestivum L.) roots were studied under hydroponic conditions. Acetic and malic acids were chosen as the representatives of LMWOAs. Uptake kinetics of lanthanum indicated that when lanthanum concentrations in the uptake solutions were high or uptake time was long lanthanum uptake by roots was enhanced by LMWAOs. After wheat was cultured in the uptake solution of lanthanum containing acetic or malic acids for 48 h the uptake of lanthanum by roots increased by 57 and 44%, respectively, compared with that in the absence of acetic and malic acids. The increase in uptake of lanthanum was determined by the ratio of the concentrations of organic acids to lanthanum in the uptake solutions. The highest uptake of lanthanum was obtained at the ratio of 5:1.     

Neutralized lanthanum solution: a largely noncolloidal ultrastructural tracer.

Lanthanum nitrate solution adjusted to pH 7.4 and pH 7.7 was subjected to column chromatography, ultrafiltration and conductivity measurements. Lanthanum concentration was measured by a colorimetric method employing eriochrome cyanine RC. Under these conditions, lanthanum was not excluded from the column by a packing with an exclusion limit of 1800 daltons. Ultrafiltration through a membrane with a filter limit of 500 daltons allowed approximately 75% of the lanthanum to pass. Conductivity measurements showed a decrease of charge of about 20% on adding sodium hydroxide to a solution of lanthanum nitrate up to a pH of 7.7. It is concluded that approximately 80% of the lanthanum exists as a charged particle of less than 500 daltons at pH 7.7; the other 20% consists of larger, possibly colloidal particles. Nonfiltered and ultrafiltered lanthanum have equally good staining and tracer properties in the electron microscope, suggesting that staining depends largely on the ultrafiltrable noncolloidal lanthanum ion.     

Characterization of the stimulus for reactive oxygen species generation in calcium-overloaded mitochondria

We have used two different probes with distinct detection properties, dichlorodihydrofluorescein diacetate and Amplex Red/horseradish peroxidase, as well as different respiratory substrates and electron transport chain inhibitors, to characterize the reactive oxygen species (ROS) generation by the respiratory chain in calcium-overloaded mitochondria. Regardless of the respiratory substrate, calcium stimulated the mitochondrial generation of ROS, which were released at both the mitochondrial-matrix side and the extra-mitochondrial space, in a way insensitive to the mitochondrial permeability transition pores inhibitor cyclosporine A. In glutamate/malate-energized mitochondria, inhibition at complex I or complex III (ubiquinone cycle) similarly modulated ROS generation at either mitochondrial-matrix side or extra-mitochondrial space; this also occurred when the backflow of electrons to complex I in succinate-energized mitochondria was inhibited. On the other hand, in succinate-energized mitochondria the modulation of ROS generation at mitochondrial-matrix side or extra-mitochondrial space depends on the site of complex III which was inhibited. These results allow a straight comparison between the effects of different respiratory substrates and electron transport chain inhibitors on ROS generation at either mitochondrial-matrix side or extra-mitochondrial space in calcium-overloaded mitochondria.     

Characterization of the stimulus for reactive oxygen species generation in calcium-overloaded mitochondria

Abstract

We have used two different probes with distinct detection properties, dichlorodihydrofluorescein diacetate and Amplex Red/horseradish peroxidase, as well as different respiratory substrates and electron transport chain inhibitors, to characterize the reactive oxygen species (ROS) generation by the respiratory chain in calcium-overloaded mitochondria. Regardless of the respiratory substrate, calcium stimulated the mitochondrial generation of ROS, which were released at both the mitochondrial-matrix side and the extra-mitochondrial space, in a way insensitive to the mitochondrial permeability transition pores inhibitor cyclosporine A. In glutamate/malate-energized mitochondria, inhibition at complex I or complex III (ubiquinone cycle) similarly modulated ROS generation at either mitochondrial-matrix side or extra-mitochondrial space; this also occurred when the backflow of electrons to complex I in succinate-energized mitochondria was inhibited. On the other hand, in succinate-energized mitochondria the modulation of ROS generation at mitochondrial-matrix side or extra-mitochondrial space depends on the site of complex III which was inhibited. These results allow a straight comparison between the effects of different respiratory substrates and electron transport chain inhibitors on ROS generation at either mitochondrial-matrix side or extra-mitochondrial space in calcium-overloaded mitochondria.     

Effect of sodium nitroprusside on heat resistance of wheat coleoptiles: Dependence on the formation and scavenging of reactive oxygen species

The effect of nitric oxide donor sodium nitroprusside (SNP) on resistance of coleoptiles of 4-day-old etiolated seedlings of wheat (Triticum aestivum L., cv. Elegiya) to damaging heating (10 min at 43°C) and possible dependence of this effect on changes in the activities of enzymes producing and scavenging reactive oxygen species (ROS) were studied. Treatment of coleoptiles with 500 μM SNP considerably boosted generation of superoxide anion radical therein. This effect was substantially suppressed by blocker of calcium channels (lanthanum chloride), calmodulin antagonist (chlorpromazine), and inhibitor of NADPH-oxidase (imidazole) but not by peroxidase inhibitor (salicylhydroxamic acid). NO donor activated antioxidant enzymes (superoxide dismutase, catalase, and soluble peroxidase) and elevated heat resistance of wheat coleoptiles. NO scavenger methylene blue, antioxidant agent ionol, calcium antagonists, and NADPH-oxidase inhibitor imidazole substantially reduced the elevation of heat resistance of wheat coleoptiles induced by NO donor. It was concluded that SNP-induced heat resistance of coleoptiles depended on calcium and ROS, whose production is probably boosted by activation of NADPH-oxidase.     

Effect of lanthanum ions (La3+) on the reactive oxygen species scavenging enzymes in wheat leaves

Physiological effects of lanthanum ions on the activities of the enzymes in the reactive oxygen species (ROS) scavenging system in leaves of wheat (Triticum aestivum L.) seedlings were studied. Wheat leaves treated in Hogland solution with 0.1 mM LaCl₃ for 48 h showed increased levels of superoxide dismutase (SOD), catalase (CAT), ascorbate-specific peroxidase (AsA-POD), and dehydroascorbate reductase (DHAR). However, a minor effect was observed on the levels of monodehydroascorbate reductase (MDAR) and glutathione reductase (GR), which regulate the release of energy required by the ROS scavenging system. The whole system was linked up by H⁺ transmission. Our results indicated that the activities of the enzymes that function directly to remove ROS were elevated by La³⁺ treatment, which is consistent with the observations that La³⁺-treated plants had increased tolerance to environmental stresses. The remaining levels of MDAR and GR suggested that these two enzymes might be regulated differently from that of the other four enzymes studied.     

Reactive Oxygen Species Activity and Antioxidant Properties of Fusarium Infected Bananas

Fusarium infection of bananas is a global problem that threatens the production of bananas. This study looks at the effects of the infection upon the reactive oxygen species (ROS) system, as well as the induced antioxidant properties in the roots, stems, leaves and fruits. Results show that there is a greater amount of damage in infected tissue samples as opposed to non‐infected. The damage was observed to be higher in the root samples. ROS assays were divided into two classes: ROS assays and ROS‐scavenging assays. Of the ROS assays, lipoxygenase was observed to be higher in the infected samples, while peroxidase (POD) and polyphenol oxidase (PPO) were significantly higher in infected stem, leaf and fruit samples. Among root samples, there was no significant difference in POD activity and PPO was lower in infected samples. Induction of ROS is important for the hypersensitive response (HR) to function properly. The ROS‐scavenging enzymes, namely ascorbate peroxidase, guaiacol peroxidase and superoxide dismutase, exhibited higher levels in the infected tissue. This is most likely to counter the build‐up of the ROS enzymes and to prevent further cell death. The increase in ROS‐scavenging assays also correlates with higher antioxidant properties as antioxidants play a critical role in regulating the HR free radicals.     

Exposure to lanthanum compound diminishes LPS-induced inflammation-associated gene expression: involvements of PKC and NF-κB signaling pathways

Lanthanum chloride, a rare earth compound, possesses antibacterial and cellular immunity regulating properties. However, the underlying molecular mechanisms remain largely unknown. In this study, we examined the effects of lanthanum chloride on the production of nitric oxide (NO) and tumor necrosis factor-α (TNF-α), the expression of inducible NO synthase (iNOS) and TNF-α in RAW 264.7 cells, a mouse macrophage cell line. We found that the LPS-elicited excessive production of NO and TNF-α in RAW 264.7 cells was inhibited significantly in the presence of lanthanum chloride, and the attenuation of iNOS and TNF-α occurred at mRNA level. Furthermore, the possible signaling components affected by lanthanum chloride in the pathway that lead to LPS-induced iNOS and TNF-α expression were explored. The results indicated the involvements of PKC/Ca²⁺ and NF-κB in the attenuation of NO and pro-inflammatory cytokine production by lanthanum chloride. Our observations suggest a possible therapeutic application of this agent for treating inflammatory diseases.     

Synthesis and characterization of new micrometer-sized radiopaque polymeric particles of narrow size distribution by a single-step swelling of uniform polystyrene template microspheres for X-ray imaging applications

Radiopaque micron-sized non-cross-linked polystyrene/poly(2-methacryloyloxyethyl(2,3,5-triiodobenzoate)) particles of narrow size distribution were prepared by a single-step swelling of uniform polystyrene template microspheres with emulsion droplets of methylene chloride containing the initiator benzoyl peroxide and the iodinated monomer 2-methacryloyloxyethyl(2,3,5-triiodobenzoate), followed by the polymerization of the monomer within the swollen template particles at 73 degrees C. Radiopaque micron-sized uniform cross-linked polystyrene/poly(2-methacryloyloxyethyl(2,3,5-triiodobenzoate)-divinylbenzene) composite particles were prepared similarly with emulsion droplets of methylene chloride containing divinylbenzene, in addition to the initiator and the iodinated monomer. Radiopaque micron-sized uniform cross-linked poly(2-methacryloyloxyethyl(2,3,5-triiodobenzoate)-divinylbenzene) particles were formed by dissolving the template polystyrene polymer belonging to the former cross-linked composite particles. Characterization of these novel radiopaque polymeric particles was performed by methods such as FTIR, TGA, DSC, SEM, XPS, elemental analysis, and light microscopy. The influence of the weight ratio [2-methacryloyloxyethyl(2,3,5-triiodobenzoate)]/[polystyrene] and [2-methacryloyloxyethyl(2,3,5-triiodobenzoate)]/[divinylbenzene] on the bulk and surface properties of the non-cross-linked and cross-linked particles, respectively was elucidated. The radiopacity of these iodinated particles was demonstrated by an imaging technique based on X-ray absorption usually used in hospitals. These novel radiopaque particles may be used for different X-ray imaging needs, e.g., blood pool, body organs, embolization, dental composition, implants, protheses, and nanocomposites.     

Mitochondrial morphology transition is an early indicator of subsequent cell death in Arabidopsis

Mitochondrial morphology and dynamics were investigated during the onset of cell death in Arabidopsis thaliana. Cell death was induced by either chemical (reactive oxygen species (ROS)) or physical (heat) shock. Changes in mitochondrial morphology in leaf tissue, or isolated protoplasts, each expressing mitochondrial-targeted green fluorescent protein (GFP), were observed by epifluorescence microscopy, and quantified. Chemical induction of ROS production, or a mild heat shock, caused a rapid and consistent change in mitochondrial morphology (termed the mitochondrial morphology transition) that preceded cell death. Treatment of protoplasts with a cell-permeable superoxide dismutase analogue, TEMPOL, blocked this morphology change. Incubation of protoplasts in micromolar concentrations of the calcium channel-blocker lanthanum chloride, or the permeability transition pore inhibitor cyclosporin A, prevented both the mitochondrial morphology transition and subsequent cell death. It is concluded that the observed mitochondrial morphology transition is an early and specific indicator of cell death and is a necessary component of the cell death process.     

TNFalpha-induced cytoprotection requires the production of free radicals within mitochondria in C2C12 myotubes

We previously reported that tumour necrosis factor alpha (TNFalpha) can mimic classic ischemic preconditioning (IPC) in both cells and heart. However, the signalling pathways involved remain incompletely understood. One potential protective pathway could be TNFalpha-induced reactive oxygen species (ROS). We hypothesized that TNFalpha cytoprotection occurs through the generation of ROS which originate within the mitochondria. C(2)C(12) myotubes were preconditioned with either a short period of hypoxia (IPC) or a low concentration of TNFalpha (0.5 ng/ml) prior to a simulated ischemic insult. ROS generation was evaluated on cells stained with dichlorofluorescin diacetate (DCFH-DA) by flow cytometry. The source of TNFalpha-induced ROS was examined with Mitotracker Red CM-H(2)XRos. The bioenergetics of the mitochondria were evaluated by investigation of the respiratory parameters and the inner mitochondrial membrane potential. Pretreatment with TNFalpha improved cell viability compared with the simulated ischemic control (TNFalpha: 75 +/- 1% versus 34 +/- 1% for the control: p<0.001). The ROS scavenger, N-2-mercaptopropionyl-glycine (MPG), reduced the viability of TNFalpha-stimulated cells to 15 +/- 1% (p<0.001 versus TNFalpha). Similar results were obtained with IPC. TNFalpha stimulation increased ROS production mainly in the mitochondria, and this increase was abolished in the presence of MPG. Addition of TNFalpha to the cells increased State 2 respiration and modestly depolarised the membrane potential prior to the ischemic insult. In conclusion, TNFalpha-induced ROS generation can occur within the mitochondria, resulting in temporal mitochondrial perturbations which may initiate the cytoprotective effect of TNFalpha.     

The use of cerebral ventriculography for verification of intracerebroventricular cannula placement in the live rat

A technique using cerebral ventriculography for verification of intracerebroventricular cannula placement in the live rat is described. A radiopaque contrast medium, diatrizoate meglumine, was injected into the right lateral ventricle through a cannula stereotaxically implanted into the brain. Radiographic visualization of the radiopaque contrast material in the lateral ventricle and the subarachnoid space verified cannula placement. Transient muscular spasms were observed in about 38% of the injected rats but no lasting changes were observed in the behavior or appearance of these rats.     

Daily grape juice consumption reduces oxidative DNA damage and plasma free radical levels in healthy Koreans

Grape contains flavonoids with antioxidant properties which are believed to be protective against various types of cancer. This antioxidative protection is possibly provided by the effective scavenging of reactive oxygen species (ROS), thus defending cellular DNA from oxidative damage and potential mutations. This study of healthy adults tested whether a daily regimen of grape juice supplementation could reduce cellular DNA damage in peripheral lymphocytes and reduce the amount of free radicals released. Sixty-seven healthy volunteers (16 women and 51 men) aged 19-57 years were given 480 ml of grape juice daily for 8 weeks in addition to their normal diet, and blood samples were drawn before and after the intervention. The DNA damage was determined by using the single cell gel (comet) assay with alkaline electrophoresis and was quantified by measuring tail length (TL). Levels of free radicals were determined by reading the lucigenin-perborate ROS generating source, using the Ultra-Weak Chemiluminescence Analyzer System. Grape juice consumption resulted in a significant decrease in lymphocyte DNA damage expressed by TL (before supplementation: 88.75 +/- 1.55 microm versus after supplementation: 70.25 +/- 1.31 microm; P=0.000 by paired t-test). Additionally, grape juice consumption for 8 weeks reduced the ROS/photon count by 15%, compared to the beginning of the study. The preventive effect of grape juice against DNA damage was simultaneously shown in both sexes. These results indicate that the consumption of grape juice may increase plasma antioxidant capacity, resulting in reduced DNA damage in peripheral lymphocytes achieved at least partially by a reduced release of ROS. Our findings support the hypothesis that polyphenolic compounds contained in grape juice exert cancer-protective effects on lymphocytes, limiting oxidative DNA damage possibly via a decrease in free radical levels.     

beta cell cytoprotective strategies: establishing the relative roles for iNOS and ROS

Cytokine-induced beta cell destruction may be mediated by the generation of nitric oxide and/or reactive oxygen species. The relative importance of NO and ROS in cytokine-induced beta cell pathophysiology remains unclear. This investigation evaluates and contrasts the cytoprotective potential of antioxidant gene transfer, versus NF-kappaB inhibition, using a degradation-resistant mutant of IkappaBalpha. NF-kappaB inhibition conferred significant protection against cytokine-induced damage whereas antioxidant overexpression failed to provide protection. Conferred cytoprotection was associated with a suppression of iNOS activation and nitrite accumulation. Our data implicates iNOS, as opposed to ROS, as the pivotal player in cytokine-induced beta cell damage. From a therapeutic standpoint, strategies aimed at targeting the activation of iNOS may harbor therapeutic potential in preserving beta cell survival in the face of proinflammatory cytokine exposure.