Mechanism of hemolysis of red blood cell mediated by ethanol

Emerging analytical tools for the detection of the third gasotransmitter H2S, a comprehensive review

BACKGROUND

Hydrogen sulfide (H2S) is currently considered among the endogenously produced gaseous molecules that exert various signaling effects in mammalian species. It is the third physiological gasotransmitter discovered so far after NO and CO. H2S was originally ranked among the toxic gases at elevated levels to humans. Currently, it is well-known that, in the cardiovascular system, H2S exerts several cardioprotective effects including vasodilation, antioxidant regulation, inhibition of inflammation, and activation of anti-apoptosis. With an increasing interest in monitoring H2S, the development of analysis methods should now follow.

AIM OF REVIEW

This review stages special emphasis on the several analytical technologies used for its determination including spectroscopic, chromatographic, and electrochemical methods. Advantages and limitations with regards to the application of each technique are highlighted with special emphasis on its employment for H2S in vivo measurement i.e., biofluids, tissues.

KEY SCIENTIFIC CONCEPTS AND IMPORTANT FINDINGS OF REVIEW

Fluorescence methods applied for H2S measurement offer an attractive non-invasive and promising approach in addition to its selectivity, however they cannot be considered as H2S-specific probes. On the other hand, colorimetric assays are among the most common methods used for in vitro H2S detection, albeit their employment in vivo H2S measurement has not yet been possible . Separation techniques such as gas or liquid chromatography offer higher selectivity compared to direct spectrophotometric or fluorescence methods especially for suitable for endpoint H2S measurements i.e. plasma or tissue samples. Despite all the developed analytical procedures used for H2S determination, the need for highly selective, much work should be devoted to resolve all the pitfalls of the current methods.

Measurement of Alcohol-Dependent Physiological Changes in Red Blood Cells Using Resistive Pulse Sensing

Alcohol exposure has been postulated to adversely affect the physiology and function of the red blood cells (RBCs). The global pervasiveness of alcohol abuse, causing health issues and social problems, makes it imperative to resolve the physiological effects of alcohol on RBC physiology. Alcohol consumed recreationally or otherwise almost immediately alters cell physiology in ways that is subtle and still unresolved. In this paper, we introduce a high-resolution device for quantitative electrofluidic measurement of changes in RBC volume upon alcohol exposure. We present an exhaustive calibration of our device using model cells to measure and resolve volume changes down to 0.6 fL. We find an RBC shrinkage of 5.3% at 0.125% ethanol (the legal limit in the United States) and a shrinkage of 18.5% at 0.5% ethanol (the lethal limit) exposure. Further, we also measure the time dependence of cell volume shrinkage (upon alcohol exposure) and then recovery (upon alcohol removal) to quantify shrinkage and recovery of RBC volumes. This work presents the first direct quantification of temporal and concentration-dependent changes in red blood cell volume upon ethanol exposure. Our device presents a universally applicable high-resolution and high-throughput platform to measure changes in cell physiology under native and diseased conditions.

Potential Role of Oral Rinses Targeting the Viral Lipid Envelope in SARS-CoV-2 Infection

Emerging studies increasingly demonstrate the importance of the throat and salivary glands as sites of virus replication and transmission in early COVID-19 disease. SARS-CoV-2 is an enveloped virus, characterized by an outer lipid membrane derived from the host cell from which it buds. While it is highly sensitive to agents that disrupt lipid biomembranes, there has been no discussion about the potential role of oral rinsing in preventing transmission. Here, we review known mechanisms of viral lipid membrane disruption by widely available dental mouthwash components that include ethanol, chlorhexidine, cetylpyridinium chloride, hydrogen peroxide, and povidone-iodine. We also assess existing formulations for their potential ability to disrupt the SARS-CoV-2 lipid envelope, based on their concentrations of these agents, and conclude that several deserve clinical evaluation. We highlight that already published research on other enveloped viruses, including coronaviruses, directly supports the idea that oral rinsing should be considered as a potential way to reduce transmission of SARS-CoV-2. Research to test this could include evaluating existing or specifically tailored new formulations in well-designed viral inactivation assays, then in clinical trials. Population-based interventions could be undertaken with available mouthwashes, with active monitoring of outcome to determine efficacy. This is an under-researched area of major clinical need.

Over-Activated Proteasome Mediates Neuroinflammation on Acute Intracerebral Hemorrhage in Rats

Background: Neuroinflammation is a hallmark in intracerebral hemorrhage (ICH) that induces secondary brain injury, leading to neuronal cell death. ER stress-triggered apoptosis and proteostasis disruption caused neuroinflammation to play an important role in various neurological disorders. The consequences of ER stress and proteostasis disruption have rarely been studied during the course of ICH development. Methods: ICH was induced by collagenase VII-S intrastriatal infusion. Animals were sacrificed at 0, 3, 6, 24, and 72 h post-ICH. Rats were determined for body weight changes, hematoma volume, and neurological deficits. Brain tissues were harvested for molecular signaling analysis either for ELISA, immunoblotting, immunoprecipitation, RT-qPCR, protein aggregation, or for histological examination. A non-selective proteasome inhibitor, MG132, was administered into the right striatum three hours prior to ICH induction. Results: ICH-induced acute proteasome over-activation caused the early degradation of the endoplasmic reticulum (ER) chaperone GRP78 and IκB protein. These exacerbations were accompanied by the elevation of pro-apoptotic CCAAT-enhancer-binding protein homologous protein (CHOP) and pro-inflammatory cytokines expression via nuclear factor-kappa B (NF-κB) signal activation. Pre-treatment with proteasome inhibitor MG132 significantly ameliorated the ICH-induced ER stress/proteostasis disruption, pro-inflammatory cytokines, neuronal cells apoptosis, and neurological deficits. Conclusions: ICH induced rapid proteasome over-activation, leading to an exaggeration of the ER stress/proteostasis disruption, and neuroinflammation might be a critical event in acute ICH pathology.

Relationships of Habitual Alcohol Intake with Erythrocyte-Related Indices in Middle-Aged Japanese Men

BACKGROUND

Anemia is induced by chronic alcohol abuse. However, it remains to be clarified whether a habitual alcohol intake affects erythrocyte-related indices in a general population.

METHODS

The subjects were 16,014 Japanese male workers aged 30-65 years. The subjects were divided into non-, occasional, and regular drinkers based on the frequency of alcohol consumption. Regular drinkers were further quantitatively divided based on their daily alcohol consumption into light, moderate, and heavy drinkers. Relationships between alcohol drinking and erythrocyte-related indices were investigated.

RESULTS

Erythrocyte counts and hemoglobin levels tended to be lower and higher, respectively, with increases in the frequency and amount of drinking. In logistic regression analysis, the odds ratios (OR) for abnormally low erythrocyte counts of moderate and heavy drinkers vs. nondrinkers were significantly higher than the reference level of 1.00 and the values tended to be higher with an increase in the alcohol intake. The OR vs. nondrinkers for abnormally low levels of hemoglobin and hematocrit were significantly lower than the reference level in all of the drinker groups and they were lowest in light drinkers among the drinker groups.

CONCLUSION

A habitual alcohol intake has different associations with erythrocyte counts and hemoglobin and with low erythrocyte counts and low hemoglobin. Thus, alcohol is thought to have diverse effects on erythropoiesis.

Safety against nephrotoxicity in paclitaxel treatment: Oral nanocarrier as an effective tool in preclinical evaluation with marked in vivo antitumor activity

Oral paclitaxel (PTXL) formulations freed from cremophor^® EL (CrEL) is always in utmost demand by the cancerous patients due to toxicities associated with the currently marketed formulation. In our previous investigation [Int. J. Pharm. 2014; 460:131], we have developed an oral oil based nanocarrier for the lipophilic drug, PTXL to target bioavailability issue and patient compliance. Here, we report in vivo antitumor activity and 28-day sub-chronic toxicity of the developed PTXL nanoemulsion. It was observed that the apoptotic potential of oral PTXL nanoemulsion significantly inhibited the growth of solid tumor (59.2 ± 7.17%; p < 0.001) without causing any explicit toxicity. The 6.5 mg/kg and 3 mg/kg oral PTXL nanoemulsion dose did not cause any notable alteration in haematological, biochemical/structural characteristics during 28-day sub-chronic toxicity studies in the experimental mice. Whereas, the toxicity of 12.8 mg/kg body weight dose showed decrease in RBC, haemoglobin and neutrophil counts. In contrast, marketed PTXL (Taxol^®) was found to be comparatively more toxic to the experimental animals. Taxol^® treatment resulted glomerulonephritis in histopathological examination, which could be correlated with increased level of creatinine and associated nephrotoxicity. This investigations conclude that the developed oral nanoemulsion presents a viable therapeutics bio-system to step towards clinical application as well as substitute CrEL based PTXL formulations.

Kinetic and Structural Aspects of the Permeabilization of Biological and Model Membranes by Lichenysin

The various lichenysins produced by Bacillus licheniformis are anionic surfactants with interesting properties. Here it is shown that lichenysin caused hemolysis of human erythrocytes, which varied with lichenysin concentration in a sigmoidal manner. The release of K(+) from red blood cells induced by lichenysin preceded the leakage of hemoglobin, and in addition, hemolysis could be impeded by the presence of compounds in the external medium having a size larger than that of PEG 3350, indicating a colloid-osmotic mechanism for hemolysis. Lichenysin also caused permeabilization of model phospholipid membranes, which was a slow process with an initial lag period of 10-20 s observed for all lichenysin concentrations. A high cholesterol ratio in the membrane decreased the extent of leakage as compared to that of pure POPC, whereas at lower ratios the effect of cholesterol was the opposite, enhancing the extent of leakage. POPE was found to decrease the extent of leakage at all the concentrations assayed, and inclusion of DPPC resulted in a considerable increase in CF leakage extent. From this scenario it was concluded that lipid membrane composition plays a role in the target membrane selectivity of lichenysin. Molecular dynamics simulations indicated that lichenysin is well distributed along the bilayer, and Na(+) ions can penetrate inside the bilayer through the lichenysin molecules. The presence of lichenysin in the membrane increases the permeability of the membrane to hydrophilic molecules facilitating its flux across the lipid palisade. The results presented in this work contribute to understanding the molecular mechanisms that explain the biological actions of lichenysin related to biomembranes.

The Effects of Ethanol on the Morphological and Biochemical Properties of Individual Human Red Blood Cells

Here, we report the results of a study on the effects of ethanol exposure on human red blood cells (RBCs) using quantitative phase imaging techniques at the level of individual cells. Three-dimensional refractive index tomograms and dynamic membrane fluctuations of RBCs were measured using common-path diffraction optical tomography, from which morphological (volume, surface area, and sphericity); biochemical (hemoglobin (Hb) concentration and Hb content); and biomechanical (membrane fluctuation) parameters were retrieved at various concentrations of ethanol. RBCs exposed to the ethanol concentration of 0.1 and 0.3% v/v exhibited cell sphericities higher than those of normal cells. However, mean surface area and sphericity of RBCs in a lethal alcoholic condition (0.5% v/v) are not statistically different with those of healthy RBCs. Meanwhile, significant decreases of Hb content and concentration in RBC cytoplasm at the lethal condition were observed. Furthermore, dynamic fluctuation of RBC membranes increased significantly upon ethanol treatments, indicating ethanol-induced membrane fluidization.

Pulmonary hypertensive crisis following ethanol sclerotherapy for a complex vascular malformation

Anhydrous ethanol is a commonly used sclerotic agent for treating vascular malformations. We describe the case of a full-term 15-day-old female with a complex venolymphatic malformation involving the face and orbit. During treatment of the lesion with ethanol sclerotherapy, she suffered acute pulmonary hypertensive crisis. We discuss the pathophysiology of pulmonary hypertension related to ethanol sclerotherapy, and propose that hemolysis plays a significant role. Recommendations for evaluation, monitoring and management of this complication are also discussed.

Ethanol causes protein precipitation--new safety issues for catheter locking techniques

OBJECTIVE

The ethanol lock technique has shown great potential to eradicate organisms in biofilms and to treat or prevent central venous catheter related infections. Following instillation of ethanol lock solution, however, the inherent density gradient between blood and ethanol causes gravity induced seepage of ethanol out of the catheter and blood influx into the catheter. Plasma proteins so are exposed to highly concentrated ethanol, which is a classic agent for protein precipitation. We aimed to investigate the precipitating effect of ethanol locks on plasma proteins as a possible cause for reported catheter occlusions.

METHODS

Plasma samples were exposed in-vitro to ethanol (concentrations ranging from 7 to 70 v/v%) and heparin lock solutions. In catheter studies designed to mimic different in-vivo situations, the catheter tip was placed in a plasma reservoir and the material contained within the catheter was analyzed after ethanol lock instillation. The samples underwent standardized investigation for protein precipitation.

RESULTS

Protein precipitation was observed in plasma samples containing ethanol solutions above a concentration of 28%, as well as in material retrieved from vertically positioned femoral catheters and jugular (subclavian) catheters simulating recumbent or head down tilt body positions. Precipitates could not be re-dissolved by dilution with plasma, urokinase or alteplase. Plasma samples containing heparin lock solutions showed no signs of precipitation.

CONCLUSIONS

Our in-vitro results demonstrate that ethanol locks may be associated with plasma protein precipitation in central venous catheters. This phenomenon could be related to occlusion of vascular access devices locked with ethanol, as has been reported. Concerns should be raised regarding possible complications upon injection or spontaneous gravity induced leakage of such irreversibly precipitated protein particles into the systemic circulation. We suggest limiting the maximum advisable concentration of ethanol to 28 v/v% in catheter lock solutions.

Bivariate and multivariate analyses of the influence of blood variables of patients submitted to Roux-en-Y gastric bypass on the stability of erythrocyte membrane against the chaotropic action of ethanol

The stability of the erythrocyte membrane, which is essential for the maintenance of cell functions, occurs in a critical region of fluidity, which depends largely on its composition and the composition and characteristics of the medium. As the composition of the erythrocyte membrane is influenced by several blood variables, the stability of the erythrocyte membrane must have relations with them. The present study aimed to evaluate, by bivariate and multivariate statistical analyses, the correlations and causal relationships between hematologic and biochemical variables and the stability of the erythrocyte membrane against the chaotropic action of ethanol. The validity of this type of analysis depends on the homogeneity of the population and on the variability of the studied parameters, conditions that can be filled by patients who undergo bariatric surgery by the technique of Roux-en-Y gastric bypass since they will suffer feeding restrictions that have great impact on their blood composition. Pathway analysis revealed that an increase in hemoglobin leads to decreased stability of the cell, probably through a process mediated by an increase in mean corpuscular volume. Furthermore, an increase in the mean corpuscular hemoglobin (MCH) leads to an increase in erythrocyte membrane stability, probably because higher values of MCH are associated with smaller quantities of red blood cells and a larger contact area between the cell membrane and ethanol present in the medium.

Toxicity studies of cremophor-free paclitaxel solid dispersion formulated by a supercritical antisolvent process

To evaluate the acute toxicity of a paclitaxel solid dispersion formulation, single dose studies in ICR mice were carried out for injectable excipients, paclitaxel solid dispersion powder, and Taxol. In the dose range of excipients used for preparing paclitaxel solid dispersion, each excipient was clinically safe, and the LD(50) for exicipients was higher than 2,000 mg/kg for both males and females. In this study, there were no remarkable clinical signs or deaths related to paclitaxel solid dispersion even at doses up to 160 mg/kg of paclitaxel. But Taxol resulted in clinical signs when it contained more than 30 mg/mL paclitaxel. The LD(50) for paclitaxel solid dispersion was above 160 mg/kg and the LD(50) for Taxol was 31.3 mg/kg, more than 5 times lower than that of paclitaxel solid dispersion. However, paclitaxel solid dispersion could not be administered i.v. at a dose exceeding 160 mg/kg, because of high viscosity. To evaluate the nephrotoxicity of paclitaxel solid dispersion, plasma level of creatinine and kidney weight were measured and compared to Taxol. At the doses administered, paclitaxel solid dispersion did not change creatinine clearance, while Taxol killed all animals at doses >15 mg/kg. To investigate membrane damage when paclitaxel formulations were injected, hemolytic activity was determined for different concentrations. Paclitaxel solid dispersion showed about 10% hemolytic activity, whereas Taxol showed about 40% hemolytic activity when it contained 2 mg of paclitaxel. Comparisons with the LD(50) value, nephrotoxicity, and hemolytic activity of Taxol suggested that Cremophor-free paclitaxel solid dispersion as an injectable formulation is a promising approach to increasing the safety and clinical efficacy of paclitaxel for treatment of cancer.

Erythrocyte and plasma protein modification in alcoholism: A possible role of acetaldehyde

Analysis of the oxidative modification of plasma and erythrocyte ghost proteins of chronic alcoholic subjects and healthy non-alcoholics has been performed. It was found that increased levels of protein carbonyls in both plasma and erythrocyte ghosts from alcoholic subjects occurred in comparison to the levels found in preparations from non-alcoholics. Plasma proteins from alcoholic subjects did not show evidence of cross-linking, although plasma protein concentration and composition were changed. In alcoholic subjects who displayed no evidence of abnormal erythrocyte morphology no cross-linking of erythrocyte ghost proteins was detectable, whereas the ghosts obtained from alcoholic subjects who displayed morphologically abnormal erythrocytes contained cross-linked proteins. The in vitro treatment with acetaldehyde of erythrocytes from non-alcoholics caused increased levels of protein carbonyls and cross-linking products in erythrocyte ghost preparations which were similar to those found in severe alcoholics. It is concluded that chronic alcohol consumption can cause abnormal erythrocyte morphology and increased erythrocyte fragility as a result of oxidation and cross-linking of erythrocyte ghost proteins. These effects can be ascribed, in part, to exposure of erythrocytes to circulatory acetaldehyde which is a product of ethanol metabolism.

Effect of triorganotin compounds on membrane permeability

Organotin compounds are widely distributed toxicants. They are membrane-active molecules with broad biological toxicity. In this contribution, we study the effect of triorganotin compounds on membrane permeability using phospholipid model membranes and human erythrocytes. Tribultyltin and triphenyltin are able to induce the release of entrapped carboxyfluorescein from large unilamellar vesicles. The rate of release is similar for phosphatidylcholine and phosphatidylserine systems and the presence of equimolar cholesterol decreases the rate of the process. Release of carboxyfluorescein is almost abolished when a non-diffusible anion like gluconate is present in the external medium, and it is restored by addition of chloride. Tributyltin is able to cause hemolysis of human erythrocytes in a dose-dependent manner. Relative kinetics determination shows that potassium leakage occurs simultaneously with hemoglobin release. Hemolysis is reduced when erythrocytes are suspended in a gluconate medium. These results indicate that triorganotin compounds are able to transport organic anions like carboxyfluorescein across phospholipids bilayers by exchange diffusion with chloride and suggest that anion exchange through erythrocyte membrane could be related to the process of hemolysis.

Percutaneous Treatment of Low Flow Vascular Malformations

Low flow vascular malformations, especially venous and macrocystic lymphatic malformations, are effectively treated by percutaneous intralesional injection of sclerosant drugs, such as ethanol and detergent sclerosant drugs. Good to excellent results are possible in 75%-90% of patients who undergo serial sclerotherapy. Most adverse effects are manageable, but severe complications can result from the intravascular administration of ethanol. It is generally recommended that the treatment of vascular malformations be performed in a multidisciplinary setting by practitioners with appropriate training and support.

Direct comparison of membrane interactions of model peptides composed of only Leu and Lys residues

We compared the properties of two peptides of identical size and amino acid composition, Ac-(LKKL)(5)-NHEt and Ac-(KL)(10)-NHEt. Both are amphipathic, but only Ac-(LKKL)(5)-NHEt is a potent promoter of negative curvature. CD studies performed in the presence of lipids confirmed that under these conditions Ac-(LKKL)(5)-NHEt forms an alpha-helix, and Ac-(KL)(10)-NHEt adopts a beta structure. We studied their binding affinity by centrifugation and isothermal titration calorimetry techniques. The Ac-(LKKL)(5)-NHEt bound to zwitterionic and anionic liposomes, while Ac-(KL)(10)-NHEt interacted mainly with anionic liposomes. Ac-(LKKL)(5)-NHEt was more lytic than Ac-(KL)(10)-NHEt for zwitterionic palmitoyloleoylphosphatidylcholine (POPC) liposomes, and for liposomes composed of lipids extracted from either sheep or human erythrocytes (RBC). Both peptides had similar lytic and lipid mixing activities for liposomes containing anionic lipids. Both peptides were highly hemolytic, with Ac-(LKKL)(5)-NHEt active against sheep RBC and Ac-(KL)(10)-NHEt more active against human RBC. From their respective minimal effective concentrations (MECs) as antimicrobial agents, we judged Ac-(KL)(10)-NHEt to be 2 to 5-fold more potent than Ac-(LKKL)(5)-NHEt in media that contained physiological concentrations of NaCl. Notwithstanding, both peptides had MECs <1 microg/mL for Escherichia coli and Pseudomonas aeruginosa and <4 microg/mL for Staphylococcus aureus and methicillin-resistant Staphylococcus aureus. Although selectivity of antimicrobial peptides for bacterial membranes may result, in part, from the preferential display of anionic residues in these membranes, inability to interact with or bind to zwitterionic phospholipids offers no guarantee that the peptide will lack appreciable cytotoxicity for host cells.

Hypochlorous acid-induced membrane pore formation in red blood cells

The hyperproduction of hypochlorous acid (HOCl), an extremely toxic biological oxidant generated by neutrophils and monocytes, is involved in the pathogenesis of many diseases. In these studies, we attempted to determine the membrane and cellular events associated with HOCl-induced erythrocyte impairment and haemolysis. In vitro human erythrocyte exposure to HOCl (0.1-1.0 mM) resulted in rapid oxidation of reduced glutathione, an increase in cell osmotic fragility and the formation of transient membrane pores. The process of glutathione oxidation depended on the [oxidant]/[cell number] ratio. The HOCl-induced haemolysis observed was apparently mediated by pore formation and altered membrane electrolyte permeability. The estimated pore radius was approximately 0.7 nm and the average number per cell was 0.01. The rate constant of HOCl-produced haemolysis depended on pH. There were significant differences in haemolysis of HOCl-treated erythrocytes which had maximal stability at pH 7.2-7.3.

Chlorodinitrobenzene-mediated damage in the human erythrocyte membrane leads to haemolysis

1-chloro-2,4-dinitrobenzene (CDNB), an intracellular glutathione-depleting agent, has been shown to have an adverse effect on erythrocyte membrane integrity. In the current study, we have demonstrated that CDNB caused haemolysis of human red blood cells (RBC) at higher concentrations (>or= 5 mM). The haemolysis induced by CDNB was preceded by the leakage of K(+) from the cells suggesting the colloid-osmotic nature of this lysis. The inclusion of molecules of increasing size in the extracellular media inhibited both the rate and extent of haemolysis thus supporting the proposal of CDNB-induced pore formation. The size of membrane lesions increased with an increase in the concentration of CDNB. SDS-PAGE demonstrated that CDNB causes the polymerisation and/or fragmentation of membrane proteins. Although CDNB has been shown to cause a drastic reduction in membrane thiols, our data suggest that the CDNB-induced formation of membrane disulfide bonds as a prima facie cause of permeability enhancement is unlikely.

The mechanism of Zn-phthalocyanine photosensitized lysis of human erythrocytes

The phthalocyanines have recently been suggested as one of most effective possible sensitizers for photodynamic therapy and the blood viral inactivation. The further characterisation of the mechanism of human red blood cell lysis and membrane alterations upon photodynamic treatment in the presence of Zn-phthalocyanine was the aim of this study. It was found that there were (2.7+/-0.4).10(7) dye binding sites per red blood cell with the association constant equal to (1.4+/-0.3).10(4) M(-1). Two types of the photosensitized haemolysis: haemolysis during irradiation ("light" haemolysis) and post-irradiation haemolysis ("dark" haemolysis) were studied. The erythrocyte membrane hyperpolarisation, membrane fluidisation and cell swelling preceded the "light" haemolysis. The modification of the erythrocyte membrane band 3 protein by DIDS (an inhibitor of anion exchange) increased the rate of the "light" haemolysis. The rate of "dark" haemolysis was higher and that of "light" haemolysis was lower in potassium media in comparison to sodium ones. The rates of photohaemolysis depended on the erythrocyte membrane potential: a decrease of membrane potential inhibited both types of haemolysis. The cell shrinkage in the presence of sucrose (up to 15 mM) inhibited the "dark" haemolysis but significantly increased the "light" haemolysis. Oxidation of intracellular oxyHb to metHb by nitrite, which drastically decreases intracellular oxygen concentration, as well as GSH concentration, inhibited the rate of the "light" haemolysis. The results allow for the conclusion that the mechanism of photochemical ("light") haemolysis is not of a colloid-osmotical type, in contrast to the post-irradiation ("dark") haemolysis. The photochemical oxidation or denaturation of band 3 protein plays a significant role in the formation of haemolytic holes. The membrane lipid peroxidation, as well as glutathione oxidation, does not participate in the process of photosensitized haemolysis. From the inhibition of "dark" haemolysis by sucrose the apparent pore radius was estimated to be about 1.1 nm. The pores appear to be transient short-lived ones, the average pore number per cell was 0.02.

In vitro hemolysis of human erythrocytes -- by plant extracts with antiplasmodial activity

Human erythrocytes were exposed in a dose dependent manner to various ethanolic plant extracts, and fractions obtained from plant parts of Calotropis procera (Ait.) R. Br. and the gum--oleo resin of Commiphora wightii (Arnott.) Bhand. These have been screened for in vitro schizontocidal activity and graded with respect to their 50% inhibitory concentration (IC(50)) derived from the twofold serial dilution of the dose range 0.0625--2 mg/ml. An attempt had been made to relate their antiplasmodial activity with their cytotoxicity as represented by the in vitro rate of hemolysis. Intact erythrocytes were found to respond with a dose--time-integral and fitted to models of pseudo first-order reaction, Michaelis--Menten equation and Hill equation with k(1), k(2) and k(3) as their rate constants, respectively. Hemolysis isotherms of flower and root of C. procera and gum--oleo resin of C. wightii extracts were representative. Erythrocytic membrane instability is possibly a major factor as has been earlier reported with ethanol and chloroquine for the cytotoxicity of these plant extracts.

Does ethanol metabolism affect erythrocyte hemolysis?

The effects of ethanol and acetaldehyde on the hemolytic stability of rabbit erythrocytes have been compared. Incubation of normal erythrocytes with ethanol facilitated both acidic and oxidative hemolysis and increased the percentages of cells that were hemolyzed at maximal rate. Acetaldehyde exerted a similar destabilizing effect on erythrocytes only in the case of oxidative hemolysis. The destabilizing effect of ethanol was observed in catalase-inactivated erythrocytes under acidic, but not oxidative, hemolysis conditions. It is concluded that the destabilizing effect of unmetabolized ethanol occurs under conditions of acidic hemolysis, whereas the destabilizing effect of the oxidation of ethanol to acetaldehyde takes place only under the conditions of oxidative hemolysis.

Serum ethanol levels in children and adults after ethanol embolization or sclerotherapy for vascular anomalies

PURPOSE

To evaluate the serum ethanol level in children and adults after ethanol embolization or sclerotherapy for vascular anomalies.

MATERIALS AND METHODS

Serum ethanol level was evaluated in 71 patients with vascular anomalies who underwent ethanol embolization, sclerotherapy, or both. Blood used to determine serum ethanol level was drawn at the end of each procedure.

RESULTS

The relationship between serum ethanol level and amount of ethanol administered was statistically significant. Results of stepwise linear regression analysis showed that the amount of ethanol administered (P <.001) and type of malformation (P =.02) were multivariate predictors of serum ethanol level. Results of logistic regression analysis revealed that the only uni- or multivariate predictor of legal intoxication was the amount of ethanol administered (P =.018). Five patients fulfilled the criteria for legal intoxication, and the mean amount of ethanol administered to these patients was 0.87 mL per kilogram of body weight +/- 0.18 (SD) (range, 0.55-0.99 mL/kg).

CONCLUSION

The volume of ethanol administered is the most reliable predictor of serum ethanol level and legal intoxication. Patients who receive up to 1.0 mL/kg ethanol during embolization or sclerotherapeutic procedures may have elevated serum ethanol levels that could put them at risk of respiratory depression, cardiac arrhythmias, seizures, rhabdomyolysis, and hypoglycemia.

Effect of bilirubin on erythrocyte shape and haemolysis, under hypotonic, aggregating or non-aggregating conditions, and correlation with cell age

The effect of unconjugated bilirubin on the morphology and haemolysis of human erythrocytes was accomplished under distinct incubation conditions: (i) hypotonic medium, with bilirubin concentrations ranging from 1 x 10(-9) to 1 x 10(-4) mol l-1; (ii) isotonic medium, with 171 mumol l-1 bilirubin, in the absence of albumin (aggregating conditions), using non-separated and age-fractionated erythrocytes; (iii) isotonic medium, with 171 mumol l-1 bilirubin, in the presence of a surplus of human serum albumin (non-aggregating conditions), and using sulfisoxazole as a bilirubin displacer (bilirubin/albumin and sulfisoxazole/ albumin molar ratios of 0.5 and 4.0, respectively). Our data showed that low concentrations of bilirubin (1 x 10(-7) to 1 x 10(-5) mol l-1) protect against hypotonic haemolysis and induce crenation, while higher bilirubin concentrations induce haemolysis and lead to membrane disruption. When aggregating conditions were used, these phenomena were reproduced, the younger cells being significantly more susceptible to crenation while the older erythrocytes showed increased susceptibility to haemolysis. In non-aggregating conditions, haemolysis was virtually absent, though crenation was evident. Based on the above observations we conclude that the first step of erythrocyte bilirubin toxicity is crenation due to an expansion of the outer membrane leaflet by bilirubin mono-anion location. This effect is more evident in younger cells and explains the protection against the hypotonic haemolysis. Insertion of bilirubin deeper into the bilayer, facilitated by higher concentrations (> or = 1 x 10(-4) mol l-1) and cell age, produces an unstable situation, where bilirubin acid aggregation is apparently the main cause for haemolysis and cell destruction.

Mechanism of hemolysis of human erythrocytes exposed to monosodium urate monohydrate crystals. Preliminary characterization of membrane pores

Microcrystals of monosodium urate monohydrate (MSUM) have the ability to cause rapid hemolysis of erythrocytes. The nature of the initial MSUM crystal-erythrocyte membrane binding interaction was investigated over a range of different ionic strength media. There was negligible binding of MSUM to erythrocyte ghost membranes in low ionic strength media such as isotonic mannitol but binding was dramatically increased in isotonic NaCl/mannitol solutions or isotonic mannitol containing 1 mM Ca2+. Hemolysis induced by MSUM crystals was preceded by the leakage of K+ from the cells suggesting a colloid-osmotic mechanism of hemolysis. The inclusion of large (oligosaccharide) molecules in the extracellular media or the modulation of the extracellular solution tonicity inhibited both the rate and extent of hemolysis supporting the concept of MSUM-induced pores followed by colloid osmotic hemolysis.

Effects of alkanols, alkanediols and glycerol on red blood cell shape and hemolysis

The physicochemical effects of a series of alkanols, alkanediols and glycerol on erythrocyte shape and hemolysis at 4 and 20 degrees C were examined. We calculated the dielectric constant of the incubation medium, Ds, and the dielectric constant of the erythrocyte membrane Dm in the presence of organic solutes. The ratio Ds/Dm = -38.48 at 20 degrees C defines the normal biconcave shape in a medium without hemolytic agents. A decrease in Ds/Dm favors externalization or internalization with consequent hemolysis. Alkanols and alkanediols convert biconcave erythrocytes into echinocytes, which is accompanied by an increase in the projected surface area. Glycerol converts biconcave erythrocytes into stomatocytes, which was accompanied by a marginal decrease in the projected surface area. Progressive externalization in alkanols and alkanediols or internalization in glycerol resulted in a decrease in the projected surface area and the formation of smooth spheres. The degree of shape change induced was related to the degree of hemolysis and the ratio Ds/Dm. A decrease in temperature reduced both the degree of shape change and hemolysis. Our results suggest that physicochemical toxicity may be a result of a temperature dependent hydrophobic interaction between the organic solutes and the membrane and is best interpreted by the ability of the solutes to change Ds and Dm. These results are discussed with respect to the physicochemical constants of the organic solutes.

Ethanol- and acetonitrile-induced inhibition of water diffusional permeability across bovine red blood cell membrane

The effect of 0-3% (v/v) ethanol and acetonitrile on water diffusional permeability of bovine and chicken red blood cells (RBCs) was studied using a pulse 1H-T2 NMR technique. Transmembrane water diffusional exchange times, tau exch, of 9.2 +/- 0.46 ms and 18.3 +/- 1.0 ms were determined for bovine and chicken erythrocytes at 27.5 degrees C, respectively. Arrhenius activation energies Ea of water diffusion were 20.4 and 35.8 kJ mol-1. Ethanol, and acetonitrile being 2-fold more effective, markedly increased both tau exch and Ea in bovine RBC as compared to the well-known mercurial inhibitor of water channels, p-chloromercuribenzene sulfonate. Chicken RBCs that have no protein water channels, were found to be completely insensitive for either agent. It was suggested that ethanol and acetonitrile partitioning into the lipid phase of bovine RBC membrane affects the permeability of CHIP28 water channel but not the lipid confined water diffusion. The results suggest that the inhibition of transmembrane movement of water via CHIP28 channels might be involved in the anti-hemolytic action of anaesthetics such as ethanol.

Methane-induced haemolysis of human erythrocytes

Human erythrocytes were exposed to high concentrations of methane and nitrogen through the application of elevated partial pressures of these gas molecules. Cell leakage (haemolysis) was measured for cells exposed to these gases under a wide range of experimental conditions. Application of methane produces haemolysis at pressures far below the hydrostatic pressures known to disrupt membrane or protein structure. The effects of changes in buffer, temperature, diffusion rate and detergents were studied. Methane acts co-operatively with detergents to produce haemolysis at much lower detergent concentration than is required in the absence of methane or in the presence of nitrogen. At sufficiently high concentrations of methane, all cells are haemolysed. Increased temperature enhances the effect. Methane produces 50% haemolysis at a concentration of about 0.33 M compared with about 7.5 M methanol required for the same degree of haemolysis.

Ethanol causes decrements in airway excretion of endogenous nitric oxide in humans

Ethanol has previously been demonstrated to inhibit excretion of endogenous nitric oxide (NO) in exhaled air from experimental animals. The aim of the present study was to elucidate if this effect also occurs in human subjects. Healthy volunteers ingested ethanol (0.25 and 1 g kg-1, 20% in orange juice). Nitric oxide in exhaled air was determined by chemiluminescence. Single-breath analysis of exhaled air was performed and peak values of NO and end expiratory levels of NO and CO2 were determined. Ethanol induced dose-dependent decrements in exhaled nitric oxide. Thus, peak values for nitric oxide in exhaled air, in the first exhalation after breath-holding for 30 s, decreased to 56 +/- 10 and 37 +/- 12% of control 60 min after ingestion of ethanol at 0.25 and 1 g kg-1, respectively. Rinsing the oral cavity (including gargling) for 15 min with 20% ethanol in juice did not significantly influence NO in exhaled air. Heart rate blood pressure and end expiratory levels of CO2 were not significantly affected by ethanol ingestion. In conclusion, ethanol decreases levels of nitric oxide in exhaled air in humans, likely by inhibition of airway formation of nitric oxide. The results might be of importance in understanding effects of ethanol and other hydrocarbons.

Alcohols produce reversible and irreversible acceleration of phospholipid flip-flop in the human erythrocyte membrane

The slow, non-mediated transmembrane movement of the lipid probes lysophosphatidylcholine, NBD-phosphatidylcholine and NBD-phosphatidylserine in human erythrocytes becomes highly enhanced in the presence of 1-alkanols (C2-C8) and 1,2-alkane diols (C4-C8). Above a threshold concentration characteristic for each alcohol, flip rates increase exponentially with the alcohol concentration. The equieffective concentrations of the alcohols decrease about 3-fold per methylene added. All 1-alkanols studied are equieffective at comparable calculated membrane concentrations. This is also observed or the 1,2-alkane diols, albeit at a 5-fold lower membrane concentration. At low alcohol concentrations, flip enhancement is reversible to a major extent upon removal of the alcohol. In contrast, a residual irreversible flip acceleration is observed following removal of the alcohol after a treatment at higher concentrations. The threshold concentrations to produce irreversible flip acceleration by 1-alkanols and 1,2-alkane diols are 1.5- and 3-fold higher than those for flip acceleration in the presence of the corresponding alcohols. A causal role in reversible flip-acceleration of a global increase of membrane fluidity or membrane polarity seems to be unlikely. Alcohols may act by increasing the probability of formation of transient structural defects in the hydrophobic barrier that already occur in the native membrane. Membrane defects responsible for irreversible flip-acceleration may result from alterations of membrane skeletal proteins by alcohols.